WorldWideScience

Sample records for short wave solar

  1. Three-Wave Resonance Modulation and Fine Structures in the Solar Short Centimeter Wave Bursts

    Institute of Scientific and Technical Information of China (English)

    王德焴; 吴洪敖; 秦至海

    1994-01-01

    A theoretical model is presented. We propose that when the radiation of solar radio bursts propagates outward as a pump wave through the conora, the three-wave resonance interaction would occur if the radio emission interacts with the MHD wave and scattering wave in the conora. This process induces a nonlinear modulation in the emission flux S. The statistical relations between the repetition rates R and S and between the modulation amplitude △S and S, observed from 1.36cm, 2cm and 3.2cm solar radio bursts could be well interpreted by this model under the conditions of imperfect matching and k2≠0. The appreciable difference in the modulation periods among the 2cm, 3.2cm and 1.36cm waves might be caused by the differences in the MHD waves joining in the modulation. Several theoretical expectations have been made from this model, which may be inspected in further observation.

  2. Solar system plasma waves

    Science.gov (United States)

    Gurnett, Donald A.

    1995-01-01

    An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

  3. Newnes short wave listening handbook

    CERN Document Server

    Pritchard, Joe

    2013-01-01

    Newnes Short Wave Listening Handbook is a guide for starting up in short wave listening (SWL). The book is comprised of 15 chapters that discuss the basics and fundamental concepts of short wave radio listening. The coverage of the text includes electrical principles; types of signals that can be heard in the radio spectrum; and using computers in SWL. The book also covers SWL equipment, such as receivers, converters, and circuits. The text will be of great use to individuals who want to get into short wave listening.

  4. Origin of solar radio waves

    International Nuclear Information System (INIS)

    Olmr, J.

    1977-01-01

    Solar radiowave radiation amounts to about 10 -7 of the total solar radiation. The solar atmosphere emits radiation of different wavelengths from a fraction of nanometer to kilometer waves. The solar radiowaves are of thermal origin and except for neutral hydrogen emission and solid body radio emission their emission always results from free electrons. The radiowave radiation active components were classified in several types, such as noise storms, flashes, flares, continuum, and flashes lasting for several minutes. The respective types are discussed and their origins shown. The mechanisms are described permitting the formation of radio waves of nonthermal origin, i.e., plasma oscillations, gyromagnetic emission, synchrotron and Cherenkov radiations. (J.P.)

  5. Ion acoustic waves in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Frank, L.A.

    1978-01-01

    Plasma wave measurements on the Helios I and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are short-wavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered

  6. Nonlinear waves in solar plasmas - a review

    International Nuclear Information System (INIS)

    Ballai, I

    2006-01-01

    Nonlinearity is a direct consequence of large scale dynamics in the solar plasmas. When nonlinear steepening of waves is balanced by dispersion, solitary waves are generated. In the vicinity of resonances, waves can steepen into nonlinear waves influencing the efficiency of energy deposition. Here we review recent theoretical breakthroughs that have lead to a greater understanding of many aspects of nonlinear waves arising in homogeneous and inhomogeneous solar plasmas

  7. Wave Tank Studies of Phase Velocities of Short Wind Waves

    Science.gov (United States)

    Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.

    Wave tank studies of phase velocities of short wind waves have been carried out using Ka-band radar and an Optical Spectrum Analyser. The phase velocities were retrieved from measured radar and optical Doppler shifts, taking into account measurements of surface drift velocities. The dispersion relationship was studied in centimetre (cm)- and millimetre(mm)-scale wavelength ranges at different fetches and wind speeds, both for a clean water surface and for water covered with surfactant films. It is ob- tained that the phase velocities do not follow the dispersion relation of linear capillary- gravity waves, increasing with fetch and, therefore, depending on phase velocities of dominant decimetre (dm)-centimetre-scale wind waves. One thus can conclude that nonlinear cm-mm-scale harmonics bound to the dominant wind waves and propagat- ing with the phase velocities of the decimetric waves are present in the wind wave spectrum. The resulting phase velocities of short wind waves are determined by re- lation between free and bound waves. The relative intensity of the bound waves in the spectrum of short wind waves is estimated. It is shown that this relation depends strongly on the surfactant concentration, because the damping effect due to films is different for free and bound waves; this results to changes of phase velocities of wind waves in the presence of surfactant films. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).

  8. Updated thermal model using simplified short-wave radiosity calculations

    International Nuclear Information System (INIS)

    Smith, J.A.; Goltz, S.M.

    1994-01-01

    An extension to a forest canopy thermal radiance model is described that computes the short-wave energy flux absorbed within the canopy by solving simplified radiosity equations describing flux transfers between canopy ensemble classes partitioned by vegetation layer and leaf slope. Integrated short-wave reflectance and transmittance-factors obtained from measured leaf optical properties were found to be nearly equal for the canopy studied. Short-wave view factor matrices were approximated by combining the average leaf scattering coefficient with the long-wave view factor matrices already incorporated in the model. Both the updated and original models were evaluated for a dense spruce fir forest study site in Central Maine. Canopy short-wave absorption coefficients estimated from detailed Monte Carlo ray tracing calculations were 0.60, 0.04, and 0.03 for the top, middle, and lower canopy layers corresponding to leaf area indices of 4.0, 1.05, and 0.25. The simplified radiosity technique yielded analogous absorption values of 0.55, 0.03, and 0.01. The resulting root mean square error in modeled versus measured canopy temperatures for all layers was less than 1°C with either technique. Maximum error in predicted temperature using the simplified radiosity technique was approximately 2°C during peak solar heating. (author)

  9. Updated thermal model using simplified short-wave radiosity calculations

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J. A.; Goltz, S. M.

    1994-02-15

    An extension to a forest canopy thermal radiance model is described that computes the short-wave energy flux absorbed within the canopy by solving simplified radiosity equations describing flux transfers between canopy ensemble classes partitioned by vegetation layer and leaf slope. Integrated short-wave reflectance and transmittance-factors obtained from measured leaf optical properties were found to be nearly equal for the canopy studied. Short-wave view factor matrices were approximated by combining the average leaf scattering coefficient with the long-wave view factor matrices already incorporated in the model. Both the updated and original models were evaluated for a dense spruce fir forest study site in Central Maine. Canopy short-wave absorption coefficients estimated from detailed Monte Carlo ray tracing calculations were 0.60, 0.04, and 0.03 for the top, middle, and lower canopy layers corresponding to leaf area indices of 4.0, 1.05, and 0.25. The simplified radiosity technique yielded analogous absorption values of 0.55, 0.03, and 0.01. The resulting root mean square error in modeled versus measured canopy temperatures for all layers was less than 1°C with either technique. Maximum error in predicted temperature using the simplified radiosity technique was approximately 2°C during peak solar heating. (author)

  10. SURFACE ALFVEN WAVES IN SOLAR FLUX TUBES

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-10

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

  11. Wave-trains in the solar wind. III

    International Nuclear Information System (INIS)

    Richter, A.K.

    1975-01-01

    Applying an Alfven-Wave-Extended-QRH-approximation and the method of characteristics, the equations of motion for outwardly propagating Alfven waves are solved analytically for three different cases of an azimuthal dependence of the background solar wind, (a) for a pure fast-slow stream configuration, (b) for the situation where the high-speed stream originates from a diverging magnetic field, and (c) for the case of (b) and an initially decreasing density configuration ('coronal hole'). The reaction of these waves on the background state as well as mode-mode coupling effects are neglected. These three solar wind models are discussed shortly. For the superimposed Alfven waves it is found, on an average, that there is a strong azimuthal dependence of all relevant parameters which, correlated with the azimuthal distributions of the solar wind variables, leads to good agreements with observations. The signature of high-speed streams and these correlations could clearly indicate solar wind streams originating from 'coronal holes'. Contrary to the purely radial solar wind, where outwardly propagating Alfven waves are exclusively refracted towards the radial direction, a refraction nearly perpendicular to the direction of the interplanetary magnetic field in the compression region and closely towards the magnetic field direction down the trailing edge and in the low-speed regime is found. (Auth.)

  12. Wave heating of the solar atmosphere

    Science.gov (United States)

    Arregui, Iñigo

    2015-04-01

    Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere.

  13. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    1999-03-01

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined by the proton temperature and by the direction of the magnetic field, which themselves depend on the latitude of WIND with respect to the heliospheric current sheet.Key words

  14. WIND observations of coherent electrostatic waves in the solar wind

    Directory of Open Access Journals (Sweden)

    A. Mangeney

    Full Text Available The time domain sampler (TDS experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s. waves: coherent wave packets of Langmuir waves with frequencies f ~ fpe, coherent wave packets with frequencies in the ion acoustic range fpi < f < fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ~ 25λD, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations. The type (wave packet or IES of the observed LF waves is mainly determined

  15. Solar atmosphere wave dynamics generated by solar global oscillating eigenmodes

    Science.gov (United States)

    Griffiths, M. K.; Fedun, V.; Erdélyi, R.; Zheng, R.

    2018-01-01

    The solar atmosphere exhibits a diverse range of wave phenomena, where one of the earliest discovered was the five-minute global acoustic oscillation, also referred to as the p-mode. The analysis of wave propagation in the solar atmosphere may be used as a diagnostic tool to estimate accurately the physical characteristics of the Sun's atmospheric layers. In this paper, we investigate the dynamics and upward propagation of waves which are generated by the solar global eigenmodes. We report on a series of hydrodynamic simulations of a realistically stratified model of the solar atmosphere representing its lower region from the photosphere to low corona. With the objective of modelling atmospheric perturbations, propagating from the photosphere into the chromosphere, transition region and low corona, generated by the photospheric global oscillations the simulations use photospheric drivers mimicking the solar p-modes. The drivers are spatially structured harmonics across the computational box parallel to the solar surface. The drivers perturb the atmosphere at 0.5 Mm above the bottom boundary of the model and are placed coincident with the location of the temperature minimum. A combination of the VALIIIC and McWhirter solar atmospheres are used as the background equilibrium model. We report how synthetic photospheric oscillations may manifest in a magnetic field free model of the quiet Sun. To carry out the simulations, we employed the magnetohydrodynamics code, SMAUG (Sheffield MHD Accelerated Using GPUs). Our results show that the amount of energy propagating into the solar atmosphere is consistent with a model of solar global oscillations described by Taroyan and Erdélyi (2008) using the Klein-Gordon equation. The computed results indicate a power law which is compared to observations reported by Ireland et al. (2015) using data from the Solar Dynamics Observatory/Atmospheric Imaging Assembly.

  16. Short-wave albedo of a pine forest

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, A.

    1985-06-01

    In this paper nine years of continuous records of the short-wave albedo above a Scotch pine forest in middle Europe were analysed. Special emphasis was given to the dependencies of the albedo on its diurnal variation, its annual variation, the solar altitude, the structure of the stand, the cloud cover, the soil moisture and the spectral reflectance. A long-termed trend of the albedo could not be found, e.g. caused by the stand growth. Finally the annual variation of the albedo of the Scotch pine forest was compared with measurements above different surface types in middle Europe.

  17. Solar Phenomena Associated with "EIT Waves"

    Science.gov (United States)

    Biesecker, D. A.; Myers, D. C.; Thompson, B. J.; Hammer, D. M.; Vourlidas, A.

    2002-01-01

    In an effort to understand what an 'EIT wave' is and what its causes are, we have looked for correlations between the initiation of EIT waves and the occurrence of other solar phenomena. An EIT wave is a coronal disturbance, typically appearing as a diffuse brightening propagating across the Sun. A catalog of EIT waves, covering the period from 1997 March through 1998 June, was used in this study. For each EIT wave, the catalog gives the heliographic location and a rating for each wave, where the rating is determined by the reliability of the observations. Since EIT waves are transient, coronal phenomena, we have looked for correlations with other transient, coronal phenomena: X-ray flares, coronal mass ejections (CMEs), and metric type II radio bursts. An unambiguous correlation between EIT waves and CMEs has been found. The correlation of EIT waves with flares is significantly weaker, and EIT waves frequently are not accompanied by radio bursts. To search for trends in the data, proxies for each of these transient phenomena are examined. We also use the accumulated data to show the robustness of the catalog and to reveal biases that must be accounted for in this study.

  18. Economics of solar energy: Short term costing

    Science.gov (United States)

    Klee, H.

    The solar economics based on life cycle costs are refuted as both imaginary and irrelevant. It is argued that predicting rates of inflation and fuel escalation, expected life, maintenance costs, and legislation over the next ten to twenty years is pure guesswork. Furthermore, given the high mobility level of the U.S. population, the average consumer is skeptical of long run arguments which will pay returns only to the next owners. In the short term cost analysis, the house is sold prior to the end of the expected life of the system. The cash flow of the seller and buyer are considered. All the relevant factors, including the federal tax credit and the added value of the house because of the solar system are included.

  19. Kinetic instabilities in the solar wind: A short review

    Energy Technology Data Exchange (ETDEWEB)

    Matteini, Lorenzo, E-mail: l.matteini@imperial.ac.uk [Imperial College London, London SW7 2AZ (United Kingdom)

    2016-03-25

    We know from in situ measurements that solar wind plasma is far from thermal equilibrium. Distribution functions of its main constituents -electrons, protons, and alpha particles-show several departures from Maxwellian, including temperature anisotropy, relative drifts and secondary populations streaming along the local magnetic field. We present a short review of recent solar wind observations of these non-thermal features and associated signatures of wave-particle interactions. Several kinetic instabilities are expected to be at work in the solar wind during its expansion, playing a role in the continuous shaping of particle distributions with distance, and regulating the macroscopic behavior of the plasma. Over the past years, modeling of these processes by means of numerical simulations has been successful in reproducing and explaining the observations; these include the evolution of the plasma due to radial expansion and the response of individual species to different kinetic instabilities. Finally, the impact of local inhomogeneities, like current sheets and turbulence, on the development of kinetic instabilities is also discussed.

  20. Nonlinear propagation of short wavelength drift-Alfven waves

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

  1. Online short-term solar power forecasting

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

    2009-01-01

    This paper describes a new approach to online forecasting of power production from PV systems. The method is suited to online forecasting in many applications and in this paper it is used to predict hourly values of solar power for horizons of up to 36 hours. The data used is fifteen......-minute observations of solar power from 21 PV systems located on rooftops in a small village in Denmark. The suggested method is a two-stage method where first a statistical normalization of the solar power is obtained using a clear sky model. The clear sky model is found using statistical smoothing techniques....... Then forecasts of the normalized solar power are calculated using adaptive linear time series models. Both autoregressive (AR) and AR with exogenous input (ARX) models are evaluated, where the latter takes numerical weather predictions (NWPs) as input. The results indicate that for forecasts up to two hours...

  2. Turbulent Structure Under Short Fetch Wind Waves

    Science.gov (United States)

    2015-12-01

    maximum 200 words ) Momentum transfer from wind forcing into the ocean is complicated by the presence of surface waves. Wind momentum and energy are...1,520 m from the mouth of the river to the deployment site ). Map created in Google Earth, October 12, 2015, http://www.google.com/earth/. 33...Doppler processing electronics for each transducer uses 14 bit analog to digital converter to digitize the 1.2 MHz acoustic frequency from the four

  3. Online Short-term Solar Power Forecasting

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

    2011-01-01

    This poster presents two approaches to online forecasting of power production from PV systems. The methods are suited for online forecasting in many applications and here they are used to predict hourly values of solar power for horizons up to 32 hours.......This poster presents two approaches to online forecasting of power production from PV systems. The methods are suited for online forecasting in many applications and here they are used to predict hourly values of solar power for horizons up to 32 hours....

  4. Solar Internal Rotation and Dynamo Waves: A Two Dimensional ...

    Indian Academy of Sciences (India)

    tribpo

    Solar Internal Rotation and Dynamo Waves: A Two Dimensional. Asymptotic Solution in the Convection Zone ... We calculate here a spatial 2 D structure of the mean magnetic field, adopting real profiles of the solar internal ... of the asymptotic solution in low (middle) and high (right panel) latitudes. field is shifted towards the ...

  5. THE EFFECTS OF WAVE ESCAPE ON FAST MAGNETOSONIC WAVE TURBULENCE IN SOLAR FLARES

    International Nuclear Information System (INIS)

    Pongkitiwanichakul, Peera; Chandran, Benjamin D. G.; Karpen, Judith T.; DeVore, C. Richard

    2012-01-01

    One of the leading models for electron acceleration in solar flares is stochastic acceleration by weakly turbulent fast magnetosonic waves ( f ast waves ) . In this model, large-scale flows triggered by magnetic reconnection excite large-wavelength fast waves, and fast-wave energy then cascades from large wavelengths to small wavelengths. Electron acceleration by large-wavelength fast waves is weak, and so the model relies on the small-wavelength waves produced by the turbulent cascade. In order for the model to work, the energy cascade time for large-wavelength fast waves must be shorter than the time required for the waves to propagate out of the solar-flare acceleration region. To investigate the effects of wave escape, we solve the wave kinetic equation for fast waves in weak turbulence theory, supplemented with a homogeneous wave-loss term. We find that the amplitude of large-wavelength fast waves must exceed a minimum threshold in order for a significant fraction of the wave energy to cascade to small wavelengths before the waves leave the acceleration region. We evaluate this threshold as a function of the dominant wavelength of the fast waves that are initially excited by reconnection outflows.

  6. Short-Term Solar Collector Power Forecasting

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Perers, Bengt

    2011-01-01

    This paper describes a new approach to online forecasting of power output from solar thermal collectors. The method is suited for online forecasting in many applications and in this paper it is applied to predict hourly values of power from a standard single glazed large area flat plate collector...... enabling tracking of changes in the system and in the surrounding conditions, such as decreasing performance due to wear and dirt, and seasonal changes such as leaves on trees. This furthermore facilitates remote monitoring and check of the system....

  7. Stochastic three-wave interaction in flaring solar loops

    Science.gov (United States)

    Vlahos, L.; Sharma, R. R.; Papadopoulos, K.

    1983-01-01

    A model is proposed for the dynamic structure of high-frequency microwave bursts. The dynamic component is attributed to beams of precipitating electrons which generate electrostatic waves in the upper hybrid branch. Coherent upconversion of the electrostatic waves to electromagnetic waves produces an intrinsically stochastic emission component which is superposed on the gyrosynchrotron continuum generated by stably trapped electron fluxes. The role of the density and temperature of the ambient plasma in the wave growth and the transition of the three wave upconversion to stochastic, despite the stationarity of the energy source, are discussed in detail. The model appears to reproduce the observational features for reasonable parameters of the solar flare plasma.

  8. Stochastic three-wave interaction in flaring solar loops

    International Nuclear Information System (INIS)

    Vlahos, L.; Sharma, R.R.; Papadopoulos, K.

    1983-01-01

    We propose a model for the dynamic structure of high-frequency microwave bursts. The dynamic component is attributed to beams of precipitating electrons which generate electrostatic waves in the upper hybrid branch. Coherent upconversion of the electrostatic waves to electromagnetic waves produces an intrinsically stochastic emission component which is superposed on the gyrosynchrotron continuum generated by stably trapped electron fluxes. The role of the density and temperature of the ambient plasma in the wave growth and the transition of the three wave upconversion to stochastic, despite the stationarity of the energy source are discussed in detail. The model appears to reproduce the observational features for reasonable parameters of the solar flare plasma

  9. Phase fluctuations model for EM wave propagation through solar scintillation at superior solar conjunction

    Science.gov (United States)

    Xu, Guanjun; Song, Zhaohui

    2017-04-01

    Traveling solar wind disturbances have a significant influence on radio wave characteristics during the superior solar conjunction communication. This paper considers the impact of solar scintillation on phase fluctuations of electromagnetic (EM) wave propagation during the superior solar conjunction. Based on the Geometric Optics approximation, the close-form approximation model for phase fluctuations is developed. Both effects of anisotropic temporal variations function of plasma irregularities and their power spectrum are presented and analyzed numerically. It is found that phase fluctuations rapidly decrease with increasing Sun-Earth-Probe angle and decrease with increasing frequency at the rate of 1/f2. Moreover, the role of various features of the solar wind irregularities and their influence on the EM wave characteristic parameters is studied and discussed. Finally, we study the phase fluctuations of typical cases in order to better understand the impact of phase fluctuations in future deep space communication scenarios during solar conjunction periods.

  10. Stability of Cubipod Armoured Roundheads in Short Crested Waves

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Andersen, Thomas Lykke; Medina, Josep R.

    2011-01-01

    The paper presents a comparison of the stability of concrete cube armour and Cubipod armour in a breakwater roundhead with slope 1:1.5, exposed to both 2-D (long-crested) and 3-D (short-crested) waves. The model tests were performed at the Hydraulics and Coastal Engineering Laboratory at Aalborg...... University, Denmark. The model tests showed that Cubipod armour is more stable than cube armour when exposed to longer waves (steepness approx. 0.025) and has equal stability to cubes in shorter waves. The Cubipod armour layer contained due to its high porosity approximately 6-17% less concrete than the cube...

  11. Traveling waves of the regularized short pulse equation

    International Nuclear Information System (INIS)

    Shen, Y; Horikis, T P; Kevrekidis, P G; Frantzeskakis, D J

    2014-01-01

    The properties of the so-called regularized short pulse equation (RSPE) are explored with a particular focus on the traveling wave solutions of this model. We theoretically analyze and numerically evolve two sets of such solutions. First, using a fixed point iteration scheme, we numerically integrate the equation to find solitary waves. It is found that these solutions are well approximated by a finite sum of hyperbolic secants powers. The dependence of the soliton's parameters (height, width, etc) to the parameters of the equation is also investigated. Second, by developing a multiple scale reduction of the RSPE to the nonlinear Schrödinger equation, we are able to construct (both standing and traveling) envelope wave breather type solutions of the former, based on the solitary wave structures of the latter. Both the regular and the breathing traveling wave solutions identified are found to be robust and should thus be amenable to observations in the form of few optical cycle pulses. (paper)

  12. Short Wavelength Electrostatic Waves in the Earth’s Magnetosheath.

    Science.gov (United States)

    1982-07-01

    to an antenna effect. Emissions likely to be ion-acoustic mode waves have been found up- stream of the bow shock ( foreshock ) in the solar wind...particles apparently reflected at the bow shock and associated with ion- acoustic mode waves in the Earth’s foreshock are also observed [Eastman et al...Res., 86, A 4493-4510, 1981. Eastman, T.E., 1.R. Anderson, L.A. Frank, and G.K. Parks, Upstream particles observed in the Earth’s foreshock region

  13. SOLAR WIND STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, J.; Gaelzer, R. [UFPEL, Pelotas (Brazil); Vinas, A. F. [NASA GSFC, Greenbelt, MD 20771 (United States); Yoon, P. H. [IPST, UMD, College Park, MD (United States); Ziebell, L. F., E-mail: joel.pavan@ufpel.edu.br, E-mail: rudi@ufpel.edu.br, E-mail: adolfo.vinas@nasa.gov, E-mail: yoonp@umd.edu, E-mail: luiz.ziebell@ufrgs.br [UFRGS, Porto Alegre (Brazil)

    2013-06-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  14. INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

    2012-10-20

    Solar acoustic waves are scattered by a sunspot due to the interaction between the acoustic waves and the sunspot. The sunspot, excited by the incident wave, generates the scattered wave. The scattered wave is added to the incident wave to form the total wave around the sunspot. The interference fringes between the scattered wave and the incident wave are visible in the intensity of the total wave because the coherent time of the incident wave is of the order of a wave period. The strength of the interference fringes anti-correlates with the width of temporal spectra of the incident wave. The separation between neighboring fringes increases with the incident wavelength and the sunspot size. The strength of the fringes increases with the radial order n of the incident wave from n = 0 to n = 2, and then decreases from n = 2 to n = 5. The interference fringes play a role analogous to holograms in optics. This study suggests the feasibility of using the interference fringes to reconstruct the scattered wavefields of the sunspot, although the quality of the reconstructed wavefields is sensitive to the noise and errors in the interference fringes.

  15. LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Krafft, C. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France); Volokitin, A. S. [IZMIRAN, Troitsk, 142190, Moscow (Russian Federation); Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr [Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, 3A Av. de la Recherche Scientifique, F-45071 Orléans Cedex 2 (France)

    2015-08-20

    Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shaping of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.

  16. Improvement of solar ethanol distillation using ultrasonic waves

    Directory of Open Access Journals (Sweden)

    Jaruwat Jareanjit

    2016-08-01

    Full Text Available This report presents a study on the use of ultrasonic waves in solar ethanol distillation to investigate the performance of ultrasonic waves at a frequency of 30 kHz and at 100 Watts that were installed in the inlet area of a 10-litre distillation tank. Based on the non-continuous distillation process (batch distillation, the experiment demonstrated that using ultrasonic waves in solar ethanol distillation caused the average concentration of hourly distilled ethanol to be higher than that of a normal system (solar ethanol distillation without ultrasonic wave at the same or higher distillation rate and hourly distillation volume. The ultrasonic wave was able to enhance the separation of ethanol from the solution (water-ethanol mixture through solar distillation. The amount of pure ethanol product from each distilled batch was clearly larger than the amount of product obtained from a normal system when the initial concentration of ethanol was lower than 50%v/v (% by volume, where an average of approximately 40% and 20% are obtained for an initial ethanol concentration of 10%v/v and 30%v/v, respectively. Furthermore, the distillation rate varied based on the solar radiation value.

  17. Short-Period Surface Wave Based Seismic Event Relocation

    Science.gov (United States)

    White-Gaynor, A.; Cleveland, M.; Nyblade, A.; Kintner, J. A.; Homman, K.; Ammon, C. J.

    2017-12-01

    Accurate and precise seismic event locations are essential for a broad range of geophysical investigations. Superior location accuracy generally requires calibration with ground truth information, but superb relative location precision is often achievable independently. In explosion seismology, low-yield explosion monitoring relies on near-source observations, which results in a limited number of observations that challenges our ability to estimate any locations. Incorporating more distant observations means relying on data with lower signal-to-noise ratios. For small, shallow events, the short-period (roughly 1/2 to 8 s period) fundamental-mode and higher-mode Rayleigh waves (including Rg) are often the most stable and visible portion of the waveform at local distances. Cleveland and Ammon [2013] have shown that teleseismic surface waves are valuable observations for constructing precise, relative event relocations. We extend the teleseismic surface wave relocation method, and apply them to near-source distances using Rg observations from the Bighorn Arche Seismic Experiment (BASE) and the Earth Scope USArray Transportable Array (TA) seismic stations. Specifically, we present relocation results using short-period fundamental- and higher-mode Rayleigh waves (Rg) in a double-difference relative event relocation for 45 delay-fired mine blasts and 21 borehole chemical explosions. Our preliminary efforts are to explore the sensitivity of the short-period surface waves to local geologic structure, source depth, explosion magnitude (yield), and explosion characteristics (single-shot vs. distributed source, etc.). Our results show that Rg and the first few higher-mode Rayleigh wave observations can be used to constrain the relative locations of shallow low-yield events.

  18. Do tidal waves exist in the solar photosphere?

    Czech Academy of Sciences Publication Activity Database

    Klvaňa, Miroslav; Švanda, M.; Krivtsov, A.; Bumba, Václav

    2004-01-01

    Roč. 28, č. 1 (2004), s. 157-164 ISSN 0351-2657. [Central European Solar Physics Meeting /1./. Bairisch Kölldorf, 23.10.2003-25.10.2003] R&D Projects: GA ČR GA205/01/0658; GA AV ČR IAA3003903; GA AV ČR KSK2043105 Institutional research plan: CEZ:AV0Z1003909 Keywords : solar photosphere * tidal waves * planets Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  19. MHz gravitational waves from short-term anisotropic inflation

    International Nuclear Information System (INIS)

    Ito, Asuka; Soda, Jiro

    2016-01-01

    We reveal the universality of short-term anisotropic inflation. As a demonstration, we study inflation with an exponential type gauge kinetic function which is ubiquitous in models obtained by dimensional reduction from higher dimensional fundamental theory. It turns out that an anisotropic inflation universally takes place in the later stage of conventional inflation. Remarkably, we find that primordial gravitational waves with a peak amplitude around 10 −26 ∼10 −27 are copiously produced in high-frequency bands 10 MHz∼100 MHz. If we could detect such gravitational waves in future, we would be able to probe higher dimensional fundamental theory.

  20. Short wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1982-01-01

    Recent observations with the ISEE-1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emissions has a characteristic parabola shape or ''festoon'' shape. The low frequency cutoff ranges from 100 Hz to 400 Hz, while the high frequency limit ranges from about 1kHz to 4kHz. The bandwidth is found to minimize for antenna orientations parallel to these wave number vectors, requiring the confinement of those vectors to a plane which contains the geocentric solar eclilptic coordinate z-axis. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest-frame wave vectors and frequencies indicate that the emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 30 meters and 600 meters. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k vector direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  1. Simple simulation training system for short-wave radio station

    Science.gov (United States)

    Tan, Xianglin; Shao, Zhichao; Tu, Jianhua; Qu, Fuqi

    2018-04-01

    The short-wave radio station is a most important transmission equipment of our signal corps, but in the actual teaching process, which exist the phenomenon of fewer equipment and more students, making the students' short-wave radio operation and practice time is very limited. In order to solve the above problems, to carry out shortwave radio simple simulation training system development is very necessary. This project is developed by combining hardware and software to simulate the voice communication operation and signal principle of shortwave radio station, and can test the signal flow of shortwave radio station. The test results indicate that this system is simple operation, human-machine interface friendly and can improve teaching more efficiency.

  2. Turbulence and Waves as Sources for the Solar Wind

    Science.gov (United States)

    Cranmer, S. R.

    2008-05-01

    Gene Parker's insights from 50 years ago provided the key causal link between energy deposition in the solar corona and the acceleration of solar wind streams. However, the community is still far from agreement concerning the actual physical processes that give rise to this energy. It is still unknown whether the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy is input more intermittently from closed loops into the open-field regions. No matter the relative importance of reconnections and loop-openings, though, we do know that waves and turbulent motions are present everywhere from the photosphere to the heliosphere, and it is important to determine how they affect the mean state of the plasma. In this presentation, I will give a summary of wave/turbulence models that seem to succeed in explaining the time-steady properties of the corona (and the fast and slow solar wind). The coronal heating and solar wind acceleration in these models comes from anisotropic turbulent cascade, which is driven by the partial reflection of low-frequency Alfven waves propagating along the open magnetic flux tubes. Specifically, a 2D model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above Parker's critical point. As predicted by earlier studies, a larger coronal expansion factor gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. Finally, I will outline the types of future observations that would be most able to test and refine these ideas.

  3. Estimating net short-wave radiation with the Bellani pyranometer

    International Nuclear Information System (INIS)

    Bernier, Y.; Plamondon, A.P.

    1983-01-01

    Two methods were developed by which daily net short-wave radiation (K∗) can be evaluated from Bellani pyranometer readings. The first method involves a simple regression equation. The second method uses a physical approach taking into account the effect of the Bellani's geometry on its response to direct and diffuse radiation throughout the day. Both methods, when tested on experimental data, tended to underestimate the measured K∗, the regression approach exhibiting a higher variance of the error [fr

  4. PROTON HEATING IN SOLAR WIND COMPRESSIBLE TURBULENCE WITH COLLISIONS BETWEEN COUNTER-PROPAGATING WAVES

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiansen; Tu, Chuanyi; Wang, Linghua; Pei, Zhongtian [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, D-24118 Kiel (Germany); Chen, Christopher H. K. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Zhang, Lei [Sate Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Salem, Chadi S.; Bale, Stuart D., E-mail: jshept@gmail.com [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2015-11-10

    Magnetohydronamic turbulence is believed to play a crucial role in heating laboratory, space, and astrophysical plasmas. However, the precise connection between the turbulent fluctuations and the particle kinetics has not yet been established. Here we present clear evidence of plasma turbulence heating based on diagnosed wave features and proton velocity distributions from solar wind measurements by the Wind spacecraft. For the first time, we can report the simultaneous observation of counter-propagating magnetohydrodynamic waves in the solar wind turbulence. As opposed to the traditional paradigm with counter-propagating Alfvén waves (AWs), anti-sunward AWs are encountered by sunward slow magnetosonic waves (SMWs) in this new type of solar wind compressible turbulence. The counter-propagating AWs and SWs correspond, respectively, to the dominant and sub-dominant populations of the imbalanced Elsässer variables. Nonlinear interactions between the AWs and SMWs are inferred from the non-orthogonality between the possible oscillation direction of one wave and the possible propagation direction of the other. The associated protons are revealed to exhibit bi-directional asymmetric beams in their velocity distributions: sunward beams appear in short, narrow patterns and anti-sunward in broad extended tails. It is suggested that multiple types of wave–particle interactions, i.e., cyclotron and Landau resonances with AWs and SMWs at kinetic scales, are taking place to jointly heat the protons perpendicular and in parallel.

  5. Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

    Science.gov (United States)

    Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

    2013-01-01

    A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

  6. Corotating pressure waves without streams in the solar wind

    International Nuclear Information System (INIS)

    Burlaga, L.F.

    1983-01-01

    Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun

  7. An Extreme-ultraviolet Wave Generating Upward Secondary Waves in a Streamer-like Solar Structure

    Science.gov (United States)

    Zheng, Ruisheng; Chen, Yao; Feng, Shiwei; Wang, Bing; Song, Hongqiang

    2018-05-01

    Extreme-ultraviolet (EUV) waves, spectacular horizontally propagating disturbances in the low solar corona, always trigger horizontal secondary waves (SWs) when they encounter the ambient coronal structure. We present the first example of upward SWs in a streamer-like structure after the passing of an EUV wave. This event occurred on 2017 June 1. The EUV wave happened during a typical solar eruption including a filament eruption, a coronal mass ejection (CME), and a C6.6 flare. The EUV wave was associated with quasi-periodic fast propagating (QFP) wave trains and a type II radio burst that represented the existence of a coronal shock. The EUV wave had a fast initial velocity of ∼1000 km s‑1, comparable to high speeds of the shock and the QFP wave trains. Intriguingly, upward SWs rose slowly (∼80 km s‑1) in the streamer-like structure after the sweeping of the EUV wave. The upward SWs seemed to originate from limb brightenings that were caused by the EUV wave. All of the results show that the EUV wave is a fast-mode magnetohydrodynamic (MHD) shock wave, likely triggered by the flare impulses. We suggest that part of the EUV wave was probably trapped in the closed magnetic fields of the streamer-like structure, and upward SWs possibly resulted from the release of slow-mode trapped waves. It is believed that the interplay of the strong compression of the coronal shock and the configuration of the streamer-like structure is crucial for the formation of upward SWs.

  8. Mid-latitude summer response of the middle atmosphere to short-term solar UV changes

    Directory of Open Access Journals (Sweden)

    P. Keckhut

    1995-06-01

    Full Text Available Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux changes. Spectral analyses are performed on 108-day windows to extract the 27-day component from temperature, wind and solar data sets. Linear regressions between these spectral harmonics show some significant correlations around 45 km at mid-latitudes. For large 27-day solar cycles, amplitudes of 2 K and 6 m s-1 are calculated for temperature data series over the south of France (44°N, and on wind data series over Volgograd (49°N, respectively. Cross-spectrum analyses have indicated correlations between these atmospheric parameters and the solar proxy with a phase lag of less than 2 days. These statistically correlative results, which provide good qualitative agreement with numerical simulations, are both obtained at mid-latitude. However, the observed amplitudes are larger than expected, with numerical models suggesting that dynamical processes such as equatorial or gravity waves may be responsible.

  9. Mid-latitude summer response of the middle atmosphere to short-term solar UV changes

    Directory of Open Access Journals (Sweden)

    P. Keckhut

    Full Text Available Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux changes. Spectral analyses are performed on 108-day windows to extract the 27-day component from temperature, wind and solar data sets. Linear regressions between these spectral harmonics show some significant correlations around 45 km at mid-latitudes. For large 27-day solar cycles, amplitudes of 2 K and 6 m s-1 are calculated for temperature data series over the south of France (44°N, and on wind data series over Volgograd (49°N, respectively. Cross-spectrum analyses have indicated correlations between these atmospheric parameters and the solar proxy with a phase lag of less than 2 days. These statistically correlative results, which provide good qualitative agreement with numerical simulations, are both obtained at mid-latitude. However, the observed amplitudes are larger than expected, with numerical models suggesting that dynamical processes such as equatorial or gravity waves may be responsible.

  10. To the complete integrability of long-wave short-wave interaction equations

    International Nuclear Information System (INIS)

    Roy Chowdhury, A.; Chanda, P.K.

    1984-10-01

    We show that the non-linear partial differential equations governing the interaction of long and short waves are completely integrable. The methodology we use is that of Ablowitz et al. though in the last section of our paper we have discussed the problem also in the light of the procedure due to Weiss et al. and have obtained a Baecklund transformation. (author)

  11. Alfvén wave dissipation in the solar chromosphere

    Science.gov (United States)

    Grant, Samuel D. T.; Jess, David B.; Zaqarashvili, Teimuraz V.; Beck, Christian; Socas-Navarro, Hector; Aschwanden, Markus J.; Keys, Peter H.; Christian, Damian J.; Houston, Scott J.; Hewitt, Rebecca L.

    2018-05-01

    Magnetohydrodynamic Alfvén waves1 have been a focus of laboratory plasma physics2 and astrophysics3 for over half a century. Their unique nature makes them ideal energy transporters, and while the solar atmosphere provides preferential conditions for their existence4, direct detection has proved difficult as a result of their evolving and dynamic observational signatures. The viability of Alfvén waves as a heating mechanism relies upon the efficient dissipation and thermalization of the wave energy, with direct evidence remaining elusive until now. Here we provide the first observational evidence of Alfvén waves heating chromospheric plasma in a sunspot umbra through the formation of shock fronts. The magnetic field configuration of the shock environment, alongside the tangential velocity signatures, distinguish them from conventional umbral flashes5. Observed local temperature enhancements of 5% are consistent with the dissipation of mode-converted Alfvén waves driven by upwardly propagating magneto-acoustic oscillations, providing an unprecedented insight into the behaviour of Alfvén waves in the solar atmosphere and beyond.

  12. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

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

  13. Ionospheric cusp flows pulsed by solar wind Alfvén waves

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    2002-02-01

    Full Text Available Pulsed ionospheric flows (PIFs in the cusp foot-print have been observed by the SuperDARN radars with periods between a few minutes and several tens of minutes. PIFs are believed to be a consequence of the interplanetary magnetic field (IMF reconnection with the magnetospheric magnetic field on the dayside magnetopause, ionospheric signatures of flux transfer events (FTEs. The quasiperiodic PIFs are correlated with Alfvénic fluctuations observed in the upstream solar wind. It is concluded that on these occasions, the FTEs were driven by Alfvén waves coupling to the day-side magnetosphere. Case studies are presented in which the dawn-dusk component of the Alfvén wave electric field modulates the reconnection rate as evidenced by the radar observations of the ionospheric cusp flows. The arrival of the IMF southward turning at the magnetopause is determined from multipoint solar wind magnetic field and/or plasma measurements, assuming plane phase fronts in solar wind. The cross-correlation lag between the solar wind data and ground magnetograms that were obtained near the cusp footprint exceeded the estimated spacecraft-to-magnetopause propagation time by up to several minutes. The difference can account for and/or exceeds the Alfvén propagation time between the magnetopause and ionosphere. For the case of short period ( < 13 min PIFs, the onset times of the flow transients appear to be further delayed by at most a few more minutes after the IMF southward turning arrived at the magnetopause. For the case of long period (30 – 40 min PIFs, the observed additional delays were 10–20 min. We interpret the excess delay in terms of an intrinsic time scale for reconnection (Russell et al., 1997 which can be explained by the surface-wave induced magnetic reconnection mechanism (Uberoi et al., 1999. Here, surface waves with wavelengths larger than the thickness of the neutral layer induce a tearing-mode instability whose rise time explains the

  14. Electron beams by shock waves in the solar corona

    International Nuclear Information System (INIS)

    Mann, G.; Klassen, A.

    2005-07-01

    Beams of energetic electrons can be generated by shock waves in the solar corona. At the Sun shock waves are produced either by flares and/or by coronal mass ejections (CMEs). They can be observed as type II bursts in the solar radio radiation. Shock accelerated electron beams appear as rapidly drifting emission stripes (so-called ''herringbones'') in dynamic radio spectra of type II bursts. A large sample of type II bursts showing ''herringbones'' was statistically analysed with respect to their properties in dynamic radio spectra. The electron beams associated with the ''herringbones'' are considered to be generated by shock drift acceleration. Then, the accelerated electrons establish a shifted loss-cone distribution in the upstream region of the associated shock wave. Such a distribution causes plasma instabilities leading to the emission of radio waves observed as ''herringbones''. Consequences of a shifted loss-cone distribution of the shock accelerated electrons are discussed in comparison with the observations of ''herringbones'' within solar type II radio bursts. (orig.)

  15. Solar pumped continuous wave carbon dioxide laser

    Science.gov (United States)

    Yesil, O.; Christiansen, W. H.

    1978-01-01

    In an effort to demonstrate the feasibility of a solar pumped laser concept, gain has been measured in a CO2-He laser medium optically pumped by blackbody radiation. Various gas mixtures of CO2 and He have been pumped by blackbody radiation emitted from an electrically heated oven. Using a CO2 laser as a probe, an optical gain coefficient of 1.8 x 10 to the -3rd/cm has been measured at 10.6 microns for a 9:1 CO2-He mixture at an oven temperature of about 1500 K, a gas temperature of about 400 K and a pressure of about 1 torr. This corresponds to a small signal gain coefficient when allowance is made for saturation effects due to the probe beam, in reasonable agreement with a theoretical value.

  16. Search for Transient Gravitational Waves in Coincidence with Short-Duration Radio Transients During 2007-2013

    Science.gov (United States)

    Abbott, B. P.; Hughey, Brennan; Zanolin, Michele; Szczepanczyk, Marek; Gill, Kiranjyot; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; hide

    2016-01-01

    We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO (Laser Interferometer Gravitational Wave Observatory), Virgo (Variability of Solar Irradiance and Gravity Oscillations) and GEO (German-UK Interferometric Detector) interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include star quakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.

  17. Observational Evidence of Magnetic Waves in the Solar Atmosphere

    Science.gov (United States)

    McIntosh, Scott W.

    2012-03-01

    The observational evidence in supporting the presence of magnetic waves in the outer solar atmosphere is growing rapidly - we will discuss recent observations and place them in context with salient observations made in the past. While the clear delineation of these magnetic wave "modes" is unclear, much can be learned about the environment in which they originated and possibly how they are removed from the system from the observations. Their diagnostic power is, as yet, untapped and their energy content (both as a mechanical source for the heating of coronal material and acceleration of the solar wind) remains in question, but can be probed observationally - raising challenges for modeling efforts. We look forward to the IRIS mission by proposing some sample observing sequences to help resolve some of the zoological issues present in the literature.

  18. On WKB expansions for Alfven waves in the solar wind

    International Nuclear Information System (INIS)

    Hollweg, J.V.

    1990-01-01

    The author reexamines the WKB expansion for toroidal Alfven waves in the solar wind, as described by equations (9) of Heinemann and Olbert (1980). His principal conclusions are as follows: (1) The WKB expansion used by Belcher (1971) and Hollweg (1973) is nonuniformly convergent. (2) Using the method of multiple scales (Nayfeh, 1981), he obtains an expansion which is uniform. (3) The uniform expansion takes into account the small modification to the Alfven wave phase speed due to spatial gradients of the background. (4) Both the uniform and nonuniform expansions reveal that each normal mode has both Elsaesser variables δz + ≠ 0 and δz - ≠ 0. Thus if δz - corresponds to the outgoing mode in a homogeneous background, an observation of δz + ≠ 0 does not necessarily imply the presence of the inward propagating mode, as is commonly assumed. (5) Even at the Alfven critical point (where V = υ A ) he finds that δz + ≠ 0. Thus incompressible MHD turbulence, which requires both δz + ≠ 0 and δz - ≠ 0, can proceed at the Alfven critical point (cf. Roberts, 1989). (6) With very few exceptions, the predictions of these calculations do not agree with recent observations (Marsch and Tu, 1990) of the power spectra of δz + and δz - in the solar wind. Thus the evolution of Alfven waves in the solar wind is governed by dynamics not included in the Heinemann and Olbert equations

  19. Short term solar radiation forecasting: Island versus continental sites

    International Nuclear Information System (INIS)

    Boland, John; David, Mathieu; Lauret, Philippe

    2016-01-01

    Due its intermittency, the large-scale integration of solar energy into electricity grids is an issue and more specifically in an insular context. Thus, forecasting the output of solar energy is a key feature to efficiently manage the supply-demand balance. In this paper, three short term forecasting procedures are applied to island locations in order to see how they perform in situations that are potentially more volatile than continental locations. Two continental locations, one coastal and one inland are chosen for comparison. At the two time scales studied, ten minute and hourly, the island locations prove to be more difficult to forecast, as shown by larger forecast errors. It is found that the three methods, one purely statistical combining Fourier series plus linear ARMA models, one combining clear sky index models plus neural net models, and a third using a clear sky index plus ARMA, give similar forecasting results. It is also suggested that there is great potential of merging modelling approaches on different horizons. - Highlights: • Solar energy forecasting is more difficult for insular than continental sites. • Fourier series plus linear ARMA models are one forecasting method tested. • Clear sky index models plus neural net models are also tested. • Clear sky index models plus linear ARMA is also an option. • All three approaches have similar skill.

  20. ENERGY CONTENT AND PROPAGATION IN TRANSVERSE SOLAR ATMOSPHERIC WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Van Doorsselaere, T. [Centre for mathematical Plasma Astrophysics, Mathematics Department, Celestijnenlaan 200B bus 2400, B-3001 Heverlee (Belgium); Soler, R. [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Verth, G., E-mail: tom.vandoorsselaere@wis.kuleuven.be [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield S3 7RH (United Kingdom)

    2013-05-10

    Recently, a significant amount of transverse wave energy has been estimated propagating along solar atmospheric magnetic fields. However, these estimates have been made with the classic bulk Alfven wave model which assumes a homogeneous plasma. In this paper, the kinetic, magnetic, and total energy densities and the flux of energy are computed for transverse MHD waves in one-dimensional cylindrical flux tube models with a piecewise constant or continuous radial density profile. There are fundamental deviations from the properties for classic bulk Alfven waves. (1) There is no local equipartition between kinetic and magnetic energy. (2) The flux of energy and the velocity of energy transfer have, in addition to a component parallel to the magnetic field, components in the planes normal to the magnetic field. (3) The energy densities and the flux of energy vary spatially, contrary to the case of classic bulk Alfven waves. This last property has the important consequence that the energy flux computed with the well known expression for bulk Alfven waves could overestimate the real flux by a factor in the range 10-50, depending on the flux tube equilibrium properties.

  1. Nonlinear two-fluid hydromagnetic waves in the solar wind: Rotational discontinuity, soliton, and finite-extent Alfven wave train solutions

    International Nuclear Information System (INIS)

    Lyu, L.H.; Kan, J.R.

    1989-01-01

    Nonlinear one-dimensional constant-profile hydromagnetic wave solutions are obtained in finite-temperature two-fluid collisionless plasmas under adiabatic equation of state. The nonlinear wave solutions can be classified according to the wavelength. The long-wavelength solutions are circularly polarized incompressible oblique Alfven wave trains with wavelength greater than hudreds of ion inertial length. The oblique wave train solutions can explain the high degree of alignment between the local average magnetic field and the wave normal direction observed in the solar wind. The short-wavelength solutions include rarefaction fast solitons, compression slow solitons, Alfven solitons and rotational discontinuities, with wavelength of several tens of ion inertial length, provided that the upstream flow speed is less than the fast-mode speed

  2. Experimental investigation of electron beam wave interactions utilising short pulses

    International Nuclear Information System (INIS)

    Wiggins, Samuel Mark

    2000-01-01

    Experiments have investigated the production of ultra-short electromagnetic pulses and their interaction with electrons in various resonant structures. Diagnostic systems used in the measurements included large bandwidth detection systems for capturing the short pulses. Deconvolution techniques have been applied to account for bandwidth limitation of the detection systems and to extract the actual pulse amplitudes and durations from the data. A Martin-Puplett interferometer has been constructed for use as a Fourier transform spectrometer. The growth of superradiant electromagnetic spikes from short duration (0.5-1.0 ns), high current (0.6-2.0 kA) electron pulses has been investigated in a Ka-band Cherenkov maser and Ka- and W-band backward wave oscillators (BWO). In the Cherenkov maser, radiation spikes were produced with a peak power ≤ 3 MW, a duration ≥ 70 ps and a bandwidth ≤ 19 %. It is shown that coherent spontaneous emission from the leading edge of the electron pulse drives these interactions, giving rise to self-amplified coherent spontaneous emission (SACSE). BWO spikes were produced with a peak power ≤ 63 MW and a pulse duration ∼ 250 ps in the Ka-band and ≤ 12 MW and ∼ 170 ps in the W-band. Evidence of superradiant evolution has been observed in the measurements of scaling laws such as power scaling with the current squared and duration scaling inversely with the fourth root of the power. An X-band free-electron maser amplifier, in which a short (1.0ns) injected radiation pulse interacts with a long (∼ 140 ns) electron beam, has been investigated. The interaction is shown to evolve in the linear regime. The peak output power was 320 kW, which corresponded to a gain, approximately constant across the band, of 42 dB. Changes to the spectrum, that occur when the input radiation pulse is injected into electrons with an energy gradient, have been analysed. (author)

  3. An analog ensemble for short-term probabilistic solar power forecast

    International Nuclear Information System (INIS)

    Alessandrini, S.; Delle Monache, L.; Sperati, S.; Cervone, G.

    2015-01-01

    Highlights: • A novel method for solar power probabilistic forecasting is proposed. • The forecast accuracy does not depend on the nominal power. • The impact of climatology on forecast accuracy is evaluated. - Abstract: The energy produced by photovoltaic farms has a variable nature depending on astronomical and meteorological factors. The former are the solar elevation and the solar azimuth, which are easily predictable without any uncertainty. The amount of liquid water met by the solar radiation within the troposphere is the main meteorological factor influencing the solar power production, as a fraction of short wave solar radiation is reflected by the water particles and cannot reach the earth surface. The total cloud cover is a meteorological variable often used to indicate the presence of liquid water in the troposphere and has a limited predictability, which is also reflected on the global horizontal irradiance and, as a consequence, on solar photovoltaic power prediction. This lack of predictability makes the solar energy integration into the grid challenging. A cost-effective utilization of solar energy over a grid strongly depends on the accuracy and reliability of the power forecasts available to the Transmission System Operators (TSOs). Furthermore, several countries have in place legislation requiring solar power producers to pay penalties proportional to the errors of day-ahead energy forecasts, which makes the accuracy of such predictions a determining factor for producers to reduce their economic losses. Probabilistic predictions can provide accurate deterministic forecasts along with a quantification of their uncertainty, as well as a reliable estimate of the probability to overcome a certain production threshold. In this paper we propose the application of an analog ensemble (AnEn) method to generate probabilistic solar power forecasts (SPF). The AnEn is based on an historical set of deterministic numerical weather prediction (NWP) model

  4. The extended hyperbolic function method and exact solutions of the long-short wave resonance equations

    International Nuclear Information System (INIS)

    Shang Yadong

    2008-01-01

    The extended hyperbolic functions method for nonlinear wave equations is presented. Based on this method, we obtain a multiple exact explicit solutions for the nonlinear evolution equations which describe the resonance interaction between the long wave and the short wave. The solutions obtained in this paper include (a) the solitary wave solutions of bell-type for S and L, (b) the solitary wave solutions of kink-type for S and bell-type for L, (c) the solitary wave solutions of a compound of the bell-type and the kink-type for S and L, (d) the singular travelling wave solutions, (e) periodic travelling wave solutions of triangle function types, and solitary wave solutions of rational function types. The variety of structure to the exact solutions of the long-short wave equation is illustrated. The methods presented here can also be used to obtain exact solutions of nonlinear wave equations in n dimensions

  5. ALFVÉN WAVES IN SIMULATIONS OF SOLAR PHOTOSPHERIC VORTICES

    Energy Technology Data Exchange (ETDEWEB)

    Shelyag, S.; Cally, P. S. [Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Victoria 3800 (Australia); Reid, A.; Mathioudakis, M. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom)

    2013-10-10

    Using advanced numerical magneto-hydrodynamic simulations of the magnetized solar photosphere, including non-gray radiative transport and a non-ideal equation of state, we analyze plasma motions in photospheric magnetic vortices. We demonstrate that apparent vortex-like motions in photospheric magnetic field concentrations do not exhibit 'tornado'-like behavior or a 'bath-tub' effect. While at each time instance the velocity field lines in the upper layers of the solar photosphere show swirls, the test particles moving with the time-dependent velocity field do not demonstrate such structures. Instead, they move in a wave-like fashion with rapidly changing and oscillating velocity field, determined mainly by magnetic tension in the magnetized intergranular downflows. Using time-distance diagrams, we identify horizontal motions in the magnetic flux tubes as torsional Alfvén perturbations propagating along the nearly vertical magnetic field lines with local Alfvén speed.

  6. Waves and Magnetism in the Solar Atmosphere (WAMIS)

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Yuan-Kuen [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Moses, John D. [Heliophysics Division, Science Mission Directorate, NASA, Washington, DC (United States); Laming, John M.; Strachan, Leonard; Tun Beltran, Samuel [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Tomczyk, Steven; Gibson, Sarah E. [High Altitude Observatory, Boulder, CO (United States); Auchère, Frédéric [Institut d' Astrophysique Spatiale, CNRS Université Paris-Sud, Orsay (France); Casini, Roberto [High Altitude Observatory, Boulder, CO (United States); Fineschi, Silvano [INAF - National Institute for Astrophysics, Astrophysical Observatory of Torino, Pino Torinese (Italy); Knoelker, Michael [High Altitude Observatory, Boulder, CO (United States); Korendyke, Clarence [Space Science Division, Naval Research Laboratory, Washington, DC (United States); McIntosh, Scott W. [High Altitude Observatory, Boulder, CO (United States); Romoli, Marco [Department of Physics and Astronomy, University of Florence, Florence (Italy); Rybak, Jan [Astronomical Institute, Slovak Academy of Sciences, Tatranska Lomnica (Slovakia); Socker, Dennis G. [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Vourlidas, Angelos [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD (United States); Wu, Qian, E-mail: yuan-kuen.ko@nrl.navy.mil [High Altitude Observatory, Boulder, CO (United States)

    2016-02-16

    Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun's generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS) investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day–night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near-space observations

  7. Waves and Magnetism in the Solar Atmosphere (WAMIS

    Directory of Open Access Journals (Sweden)

    Yuan-Kuen eKo

    2016-02-01

    Full Text Available Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun’s generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day-night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near

  8. Waves and Magnetism in the Solar Atmosphere (WAMIS)

    International Nuclear Information System (INIS)

    Ko, Yuan-Kuen; Moses, John D.; Laming, John M.; Strachan, Leonard; Tun Beltran, Samuel; Tomczyk, Steven; Gibson, Sarah E.; Auchère, Frédéric; Casini, Roberto; Fineschi, Silvano; Knoelker, Michael; Korendyke, Clarence; McIntosh, Scott W.; Romoli, Marco; Rybak, Jan; Socker, Dennis G.; Vourlidas, Angelos; Wu, Qian

    2016-01-01

    Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun's generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS) investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day–night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near-space observations

  9. Evidence for four- and three-wave interactions in solar type III radio emissions

    Directory of Open Access Journals (Sweden)

    G. Thejappa

    2013-08-01

    Full Text Available The high time resolution observations obtained by the STEREO/WAVES experiment show that in the source regions of solar type III radio bursts, Langmuir waves often occur as intense localized wave packets with short durations of only few ms. One of these wave packets shows that it is a three-dimensional field structure with WLneTe ~ 10−3, where WL is the peak energy density, and ne and Te are the electron density and temperature, respectively. For this wave packet, the conditions of the oscillating two-stream instability (OTSI and supersonic collapse are satisfied within the error range of determination of main parameters. The density cavity, observed during this wave packet indicates that its depth, width and temporal coincidence are consistent with those of a caviton, generated by the ponderomotive force of the collapsing wave packet. The spectrum of each of the parallel and perpendicular components of the wave packet contains a primary peak at fpe, two secondary peaks at fpe ± fS and a low-frequency enhancement below fS, which, as indicated by the frequency and wave number resonance conditions, and the fast Fourier transform (FFT-based tricoherence spectral peak at (fpe, fpe, fpe + fS, fpe − fS, are coupled to each other by the OTSI type of four-wave interaction (fpe is the local electron plasma frequency and fS is the frequency of ion sound waves. In addition to the primary peak at fpe, each of these spectra also contains a peak at 2fpe, which as indicated by the frequency and wave number resonance conditions, and the wavelet-based bicoherence spectral peak at (fpe, fpe, appears to correspond to the second harmonic electromagnetic waves generated as a result of coalescence of oppositely propagating sidebands excited by the OTSI. Thus, these observations for the first time provide combined evidence that (1 the OTSI and related strong turbulence processes play a significant role in the stabilization of the electron beam, (2 the coalescence

  10. Hydromagnetic theory of solar sectors: slow hydromagnetic waves

    International Nuclear Information System (INIS)

    Suess, S.T.

    1975-01-01

    Magnetic sectors on the sun are a feature, when the solar dipole field is subtracted, reminiscent of grapefruit sections in terms of the boundaries described by the magnetic field polarity change. One possible suggestion for the origin of these sectors is that they are hydromagnetic waves controlled by the rotation, toroidal magnetic field, and stratification within the convection zone of the sun. The merits of this suggestion are evaluated with respect to the observations and a specific theoretical model. 4 figs, 38 refs. (U.S.)

  11. STEREO OBSERVATIONS OF FAST MAGNETOSONIC WAVES IN THE EXTENDED SOLAR CORONA ASSOCIATED WITH EIT/EUV WAVES

    International Nuclear Information System (INIS)

    Kwon, Ryun-Young; Ofman, Leon; Kramar, Maxim; Olmedo, Oscar; Davila, Joseph M.; Thompson, Barbara J.; Cho, Kyung-Suk

    2013-01-01

    We report white-light observations of a fast magnetosonic wave associated with a coronal mass ejection observed by STEREO/SECCHI/COR1 inner coronagraphs on 2011 August 4. The wave front is observed in the form of density compression passing through various coronal regions such as quiet/active corona, coronal holes, and streamers. Together with measured electron densities determined with STEREO COR1 and Extreme UltraViolet Imager (EUVI) data, we use our kinematic measurements of the wave front to calculate coronal magnetic fields and find that the measured speeds are consistent with characteristic fast magnetosonic speeds in the corona. In addition, the wave front turns out to be the upper coronal counterpart of the EIT wave observed by STEREO EUVI traveling against the solar coronal disk; moreover, stationary fronts of the EIT wave are found to be located at the footpoints of deflected streamers and boundaries of coronal holes, after the wave front in the upper solar corona passes through open magnetic field lines in the streamers. Our findings suggest that the observed EIT wave should be in fact a fast magnetosonic shock/wave traveling in the inhomogeneous solar corona, as part of the fast magnetosonic wave propagating in the extended solar corona.

  12. Short-range solar radiation forecasts over Sweden

    Directory of Open Access Journals (Sweden)

    T. Landelius

    2018-04-01

    Full Text Available In this article the performance for short-range solar radiation forecasts by the global deterministic and ensemble models from the European Centre for Medium-Range Weather Forecasts (ECMWF is compared with an ensemble of the regional mesoscale model HARMONIE-AROME used by the national meteorological services in Sweden, Norway and Finland. Note however that only the control members and the ensemble means are included in the comparison. The models resolution differs considerably with 18 km for the ECMWF ensemble, 9 km for the ECMWF deterministic model, and 2.5 km for the HARMONIE-AROME ensemble.The models share the same radiation code. It turns out that they all underestimate systematically the Direct Normal Irradiance (DNI for clear-sky conditions. Except for this shortcoming, the HARMONIE-AROME ensemble model shows the best agreement with the distribution of observed Global Horizontal Irradiance (GHI and DNI values. During mid-day the HARMONIE-AROME ensemble mean performs best. The control member of the HARMONIE-AROME ensemble also scores better than the global deterministic ECMWF model. This is an interesting result since mesoscale models have so far not shown good results when compared to the ECMWF models.Three days with clear, mixed and cloudy skies are used to illustrate the possible added value of a probabilistic forecast. It is shown that in these cases the mesoscale ensemble could provide decision support to a grid operator in terms of forecasts of both the amount of solar power and its probabilities.

  13. Probing Intrinsic Properties of Short Gamma-Ray Bursts with Gravitational Waves.

    Science.gov (United States)

    Fan, Xilong; Messenger, Christopher; Heng, Ik Siong

    2017-11-03

    Progenitors of short gamma-ray bursts are thought to be neutron stars coalescing with their companion black hole or neutron star, which are one of the main gravitational wave sources. We have devised a Bayesian framework for combining gamma-ray burst and gravitational wave information that allows us to probe short gamma-ray burst luminosities. We show that combined short gamma-ray burst and gravitational wave observations not only improve progenitor distance and inclination angle estimates, they also allow the isotropic luminosities of short gamma-ray bursts to be determined without the need for host galaxy or light-curve information. We characterize our approach by simulating 1000 joint short gamma-ray burst and gravitational wave detections by Advanced LIGO and Advanced Virgo. We show that ∼90% of the simulations have uncertainties on short gamma-ray burst isotropic luminosity estimates that are within a factor of two of the ideal scenario, where the distance is known exactly. Therefore, isotropic luminosities can be confidently determined for short gamma-ray bursts observed jointly with gravitational waves detected by Advanced LIGO and Advanced Virgo. Planned enhancements to Advanced LIGO will extend its range and likely produce several joint detections of short gamma-ray bursts and gravitational waves. Third-generation gravitational wave detectors will allow for isotropic luminosity estimates for the majority of the short gamma-ray burst population within a redshift of z∼1.

  14. An Investigation of Short Circuits in All-solution Processed and All-organic Solar Cells

    OpenAIRE

    Johansson, Jim

    2015-01-01

    Organic solar cells have shown great promise of becoming a cheaper alternative to inorganic solar cells. Additionally, they can also be made semitransparent. To avoid using expensive indium tin oxide electrodes in organic solar cells the electrodes can be made from conductive polymer, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). However, these so-called PEDOT-PEDOT solar cells are prone to short-circuiting. The work behind this thesis thus aimed to find the cause of the...

  15. Leaf temperature and transpiration of rice plants in relation to short-wave radiation and wind speed

    International Nuclear Information System (INIS)

    Ito, D.; Haseba, T.

    1984-01-01

    Leaf temperature and transpiration amount of rice plants were measured in a steady environment in a laboratory and in field situations. The plants set in Wagner pots were used. Experiments were carried out at the tillering and booting stages, and on the date of maturity. Measured leaf temperatures and transpiration rates were analyzed in connection with incident short-wave radiation on a leaf and wind speed measured simultaneously.Instantaneous supplying and turning-off of steady artificial light caused cyclic changes in leaf temperature and transpiration. Leaf temperature dropped in feeble illumination compared with the steady temperature in the preceeding dark.On the date of maturity, a rice plant leaf was warmer than the air, even in feeble light. Then, the leaf-air temperature difference and transpiration rate showed approximately linear increases with short-wave radiation intensity. On the same date, an increase in wind speed produced a decrease in leaf-air temperature difference, i.e., leaf temperature dropped, and an increase in transpiration rate. The rates of both changes in leaf temperature and transpiration rate were fairly large in a range of wind speed below about 1m/s.For rice plants growing favorably from the tillering stage through the booting stage, the leaves were considerably cooler than the air, even in an intense light and/or solar radiation. The leaf temperature showed the lowest value at short-wave radiations between 0.15 and 0.20ly/min, at above which the leaf temperature rised with an increase in short-wave radiation until it approached the air temperature. Transpiration rate of rice plants increased rapidly with an increase in short-wave radiation ranging below 0.2 or 0.3ly/min, at above which the increase in transpiration rate slowed.The relationships between leaf temperature and/or transpiration rate and wind speed and/or incident short-wave radiation (solar radiation) which were obtained experimentally, supported the relationships

  16. Alive and well: A short review about standard solar models

    Energy Technology Data Exchange (ETDEWEB)

    Serenelli, Aldo [Campus UAB, Carrer de Can Magrans S/N, Instituto de Ciencias del Espacio (ICE/CSIC-IEEC), Cerdanyola del Valles (Spain)

    2016-04-15

    Standard solar models (SSMs) provide a reference framework across a number of research fields: solar and stellar models, solar neutrinos, particle physics the most conspicuous among them. The accuracy of the physical description of the global properties of the Sun that SSMs provide has been challenged in the last decade by a number of developments in stellar spectroscopic techniques. Over the same period of time, solar neutrino experiments, and Borexino in particular, have measured the four solar neutrino fluxes from the pp-chains that are associated with 99% of the nuclear energy generated in the Sun. Borexino has also set the most stringent limit on CNO energy generation, only ∝ 40% larger than predicted by SSMs. More recently, and for the first time, radiative opacity experiments have been performed at conditions that closely resemble those at the base of the solar convective envelope. In this article, we review these developments and discuss the current status of SSMs, including its intrinsic limitations. (orig.)

  17. The influence of solar wind variability on magnetospheric ULF wave power

    International Nuclear Information System (INIS)

    Pokhotelov, D.; Rae, I.J.; Mann, I.R.

    2015-01-01

    Magnetospheric ultra-low frequency (ULF) oscillations in the Pc 4-5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF) orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind-IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996-2004) of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature), plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind-magnetosphere coupling.

  18. The influence of solar wind variability on magnetospheric ULF wave power

    Directory of Open Access Journals (Sweden)

    D. Pokhotelov

    2015-06-01

    Full Text Available Magnetospheric ultra-low frequency (ULF oscillations in the Pc 4–5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind–IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996–2004 of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature, plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind–magnetosphere coupling.

  19. Scattered P'P' waves observed at short distances

    Science.gov (United States)

    Earle, Paul S.; Rost, Sebastian; Shearer, Peter M.; Thomas, Christine

    2011-01-01

    We detect previously unreported 1 Hz scattered waves at epicentral distances between 30° and 50° and at times between 2300 and 2450 s after the earthquake origin. These waves likely result from off-azimuth scattering of PKPbc to PKPbc in the upper mantle and crust and provide a new tool for mapping variations in fine-scale (10 km) mantle heterogeneity. Array beams from the Large Aperture Seismic Array (LASA) clearly image the scattered energy gradually emerging from the noise and reaching its peak amplitude about 80 s later, and returning to the noise level after 150 s. Stacks of transverse versus radial slowness (ρt, ρr) show two peaks at about (2, -2) and (-2,-2) s/°, indicating the waves arrive along the major arc path (180° to 360°) and significantly off azimuth. We propose a mantle and surface PKPbc to PKPbc scattering mechanism for these observations because (1) it agrees with the initiation time and distinctive slowness signature of the scattered waves and (2) it follows a scattering path analogous to previously observed deep-mantle PK•KP scattering (Chang and Cleary, 1981). The observed upper-mantle scattered waves and PK•KP waves fit into a broader set of scattered waves that we call P′•d•P′, which can scatter from any depth, d, in the mantle.

  20. ALFVEN WAVE REFLECTION AND TURBULENT HEATING IN THE SOLAR WIND FROM 1 SOLAR RADIUS TO 1 AU: AN ANALYTICAL TREATMENT

    International Nuclear Information System (INIS)

    Chandran, Benjamin D. G.; Hollweg, Joseph V.

    2009-01-01

    We study the propagation, reflection, and turbulent dissipation of Alfven waves in coronal holes and the solar wind. We start with the Heinemann-Olbert equations, which describe non-compressive magnetohydrodynamic fluctuations in an inhomogeneous medium with a background flow parallel to the background magnetic field. Following the approach of Dmitruk et al., we model the nonlinear terms in these equations using a simple phenomenology for the cascade and dissipation of wave energy and assume that there is much more energy in waves propagating away from the Sun than waves propagating toward the Sun. We then solve the equations analytically for waves with periods of hours and longer to obtain expressions for the wave amplitudes and turbulent heating rate as a function of heliocentric distance. We also develop a second approximate model that includes waves with periods of roughly one minute to one hour, which undergo less reflection than the longer-period waves, and compare our models to observations. Our models generalize the phenomenological model of Dmitruk et al. by accounting for the solar wind velocity, so that the turbulent heating rate can be evaluated from the coronal base out past the Alfven critical point-that is, throughout the region in which most of the heating and acceleration occurs. The simple analytical expressions that we obtain can be used to incorporate Alfven-wave reflection and turbulent heating into fluid models of the solar wind.

  1. Full-wave solution of short impulses in inhomogeneous plasma

    International Nuclear Information System (INIS)

    Ferencz, Orsolya E.

    2005-01-01

    In this paper the problem of real impulse propagation in arbitrarily inhomogeneous media will be presented on a fundamentally new, general, theoretical way. The general problem of wave propagation of monochromatic signals in inhomogeneous media was enlightened. The earlier theoretical models for spatial inhomogeneities have some errors regarding the structure of the resultant signal originated from backward and forward propagating parts. The application of the method of inhomogeneous basic modes (MIBM) and the complete full-wave solution of arbitrarily shaped non-monochromatic plane waves in plasmas made it possible to obtain a better description of the problem, on a fully analytical way, directly from Maxwell's equations. The model investigated in this paper is inhomogeneous of arbitrary order (while the wave pattern can exist), anisotropic (magnetized), linear, cold plasma, in which the gradient of the one-dimensional spatial inhomogeneity is parallel to the direction of propagation. (author)

  2. Models for short-wave instability in inviscid shear flows

    Science.gov (United States)

    Grimshaw, Roger

    1999-11-01

    The generation of instability in an invsicid fluid occurs by a resonance between two wave modes, where here the resonance occurs by a coincidence of phase speeds for a finite, non-zero wavenumber. We show that in the weakly nonlinear limit, the appropriate model consists of two coupled equations for the envelopes of the wave modes, in which the nonlinear terms are balanced with low-order cross-coupling linear dispersive terms rather than the more familiar high-order terms which arise in the nonlinear Schrodinger equation, for instance. We will show that this system may either contain gap solitons as solutions in the linearly stable case, or wave breakdown in the linearly unstable case. In this latter circumstance, the system either exhibits wave collapse in finite time, or disintegration into fine-scale structures.

  3. Full-wave solution of short impulses in inhomogeneous plasma

    Indian Academy of Sciences (India)

    ... in arbitrarily inhomogeneous media will be presented on a fundamentally new, ... The general problem of wave propagation of monochromatic signals in inhomogeneous media was enlightened in [1]. ... Pramana – Journal of Physics | News.

  4. Short-Term Wave Forecasting for Real-Time Control of Wave Energy Converters

    OpenAIRE

    Fusco, Francesco; Ringwood, John

    2010-01-01

    Real-time control of wave energy converters requires knowledge of future incident wave elevation in order to approach optimal efficiency of wave energy extraction. We present an approach where the wave elevation is treated as a time series and it is predicted only from its past history. A comparison of a range of forecasting methodologies on real wave observations from two different locations shows how the relatively simple linear autoregressive model, which implicitly models the cyclical beh...

  5. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  6. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    2003-07-01

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  7. Short-wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1985-01-01

    Recent observations with the ISEE 1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emission has a characteristic parabola shape or ''festoon'' shape. The low-frequency cutoff ranges from 100 to 400 Hz, while the high-frequency limit ranges from about 1 to 4 kHz. The bandwidth is found to minimize for antenna orientations parallel to the wave vectors. The wave vector does not appear to be related to the local magnetic field, the plasma flow velocity, or the spacecraft-sun directions. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler-shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest frame wave vectors and frequencies indicate that emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 40 and 600 m. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  8. TEMPERATURE GRADIENTS IN THE SOLAR ATMOSPHERE AND THE ORIGIN OF CUTOFF FREQUENCY FOR TORSIONAL TUBE WAVES

    International Nuclear Information System (INIS)

    Routh, S.; Musielak, Z. E.; Hammer, R.

    2010-01-01

    Fundamental modes supported by a thin magnetic flux tube embedded in the solar atmosphere are typically classified as longitudinal, transverse, and torsional waves. If the tube is isothermal, then the propagation of longitudinal and transverse tube waves is restricted to frequencies that are higher than the corresponding global cutoff frequency for each wave. However, no such global cutoff frequency exists for torsional tube waves, which means that a thin and isothermal flux tube supports torsional tube waves of any frequency. In this paper, we consider a thin and non-isothermal magnetic flux tube and demonstrate that temperature gradients inside this tube are responsible for the origin of a cutoff frequency for torsional tube waves. The cutoff frequency is used to determine conditions for the wave propagation in the solar atmosphere, and the obtained results are compared to the recent observational data that support the existence of torsional tube waves in the Sun.

  9. Benefits of up-wave measurements in linear short-term wave forecasting for wave energy applications

    OpenAIRE

    Paparella, Francesco; Monk, Kieran; Winands, Victor; Lopes, Miguel; Conley, Daniel; Ringwood, John

    2014-01-01

    The real-time control of wave energy converters requires the prediction of the wave elevation at the location of the device in order to maximize the power extracted from the waves. One possibility is to predict the future wave elevation by combining its past history with the spatial information coming from a sensor which measures the free surface elevation upwave of the wave energy converter. As an application example, the paper focuses on the prediction of the wave eleva...

  10. Upper Meter Processes: Short Wind Waves, Surface Flow, and Micro-Turbulence

    National Research Council Canada - National Science Library

    Jaehne, Bernd

    2000-01-01

    The primary goal of this project was to advance the knowledge of small-scale air-sea interaction processes at the ocean surface, focussing on the dynamics of short waves, the surface flow field and the micro-turbulence...

  11. Reserve Requirement Impacts of Microgrid Integration of Wind, Solar, and Ocean Wave Power Generation

    OpenAIRE

    Ortego Trujillo, Patxi

    2016-01-01

    The ocean wave energy is a free and abundant resource which has led to exploring new methods to take advantage of the energy in an efficient and profitable way. The wave energy harnessing techniques are not as mature as other renewable energy resources ones such as wind or solar. Nevertheless, in recent years wave energy converters (WECs) have been gaining attention and restoring confidence worldwide in their role to meet the increasing demands and strict environmental standards Ocean wave po...

  12. Sinusoidal Wave Estimation Using Photogrammetry and Short Video Sequences

    Directory of Open Access Journals (Sweden)

    Ewelina Rupnik

    2015-12-01

    Full Text Available The objective of the work is to model the shape of the sinusoidal shape of regular water waves generated in a laboratory flume. The waves are traveling in time and render a smooth surface, with no white caps or foam. Two methods are proposed, treating the water as a diffuse and specular surface, respectively. In either case, the water is presumed to take the shape of a traveling sine wave, reducing the task of the 3D reconstruction to resolve the wave parameters. The first conceived method performs the modeling part purely in 3D space. Having triangulated the points in a separate phase via bundle adjustment, a sine wave is fitted into the data in a least squares manner. The second method presents a more complete approach for the entire calculation workflow beginning in the image space. The water is perceived as a specular surface, and the traveling specularities are the only observations visible to the  cameras, observations that are notably single image. The depth ambiguity is removed given additional constraints encoded within the law of reflection and the modeled parametric surface. The observation and constraint equations compose a single system of equations that is solved with the method of least squares adjustment. The devised approaches are validated against the data coming from a capacitive level sensor and on physical targets floating on the surface. The outcomes agree to a high degree.

  13. Solar photovoltaics in Sri Lanka: a short history

    International Nuclear Information System (INIS)

    Gunaratne, L.

    1994-01-01

    With a significant unelectrified rural population, Sri Lanka has followed the evolution of solar photovoltaic (PV) technology in the West very closely since the 1970s as terrestrial applications for photovoltaics were developed. It was not until 1980 that the Sri Lankan government embarked on the promotion of solar photovoltaics for rural domestic use when the Ceylon Electricity Board formed the Energy Unit. In addition, Australian and Sri Lankan government-funded pilot projects have given the local promoters further valuable insight into how and how not to promote solar photovoltaics. The establishment of community-based solar photovoltaic programmes by non-governmental organizations has developed a novel approach to bridge the gap between this state-of-the-art technology and the remotely located end-users. (author)

  14. A numerical study of lowest-order short-crested water wave instabilities

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Madsen, Per A.

    2005-01-01

    This work presents the first numerical simulations of the long-term evolution of doubly-periodic short-crested wave instabilities, which are the simplest cases involving the three-dimensional instability of genuinely three-dimensional progressive water waves. The simulated evolutions reveal quali...

  15. Short-term statistics of waves measured off Ratnagiri, eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Amrutha, M.M.; SanilKumar, V.

    coast of India have been analyzed to study the short-term statistics of waves covering full one year period. The study indicates that the values of the observed maximum wave height as a function of duration are not consistent with the theoretical...

  16. 3-D Effects Force Reduction of Short-Crested Non-Breaking Waves on Caissons

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Z.

    1998-01-01

    The effect of wave short-crestedness on the horizontal wave force on a caisson is twofold. The one is the force reduction due to the reduction of point pressure on the caisson, named point-pressure reduction. The other is the force reduction due to the fact that the peak pressures do not occur si...

  17. Short range correlations in the pion s-wave self-energy of pionic atoms

    OpenAIRE

    Salcedo, L. L.; Holinde, K.; Oset, E.; Schütz, C.

    1995-01-01

    We evaluate the contribution of second order terms to the pion-nucleus s-wave optical potential of pionic atoms generated by short range nuclear correlation. The corrections are sizeable because they involve the isoscalar s-wave $\\pi N$ amplitude for half off-shell situations where the amplitude is considerably larger than the on-shell one. In addition, the s-wave optical potential is reanalyzed by looking at all the different conventional contributions together lowest order, Pauli corrected ...

  18. An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images

    Science.gov (United States)

    Weberg, Micah J.; Morton, Richard J.; McLaughlin, James A.

    2018-01-01

    Recent instrumentation has demonstrated that the solar atmosphere supports omnipresent transverse waves, which could play a key role in energizing the solar corona. Large-scale studies are required in order to build up an understanding of the general properties of these transverse waves. To help facilitate this, we present an automated algorithm for identifying and tracking features in solar images and extracting the wave properties of any observed transverse oscillations. We test and calibrate our algorithm using a set of synthetic data, which includes noise and rotational effects. The results indicate an accuracy of 1%–2% for displacement amplitudes and 4%–10% for wave periods and velocity amplitudes. We also apply the algorithm to data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and find good agreement with previous studies. Of note, we find that 35%–41% of the observed plumes exhibit multiple wave signatures, which indicates either the superposition of waves or multiple independent wave packets observed at different times within a single structure. The automated methods described in this paper represent a significant improvement on the speed and quality of direct measurements of transverse waves within the solar atmosphere. This algorithm unlocks a wide range of statistical studies that were previously impractical.

  19. Errors in short circuit measurements due to spectral mismatch between sunlight and solar simulators

    Science.gov (United States)

    Curtis, H. B.

    1976-01-01

    Errors in short circuit current measurement were calculated for a variety of spectral mismatch conditions. The differences in spectral irradiance between terrestrial sunlight and three types of solar simulator were studied, as well as the differences in spectral response between three types of reference solar cells and various test cells. The simulators considered were a short arc xenon lamp AMO sunlight simulator, an ordinary quartz halogen lamp, and an ELH-type quartz halogen lamp. Three types of solar cells studied were a silicon cell, a cadmium sulfide cell and a gallium arsenide cell.

  20. Annual Properties of Transverse Waves in the Corona over most of Solar Cycle 24

    Science.gov (United States)

    Weberg, M. J.; Morton, R. J.; McLaughlin, J. A.

    2017-12-01

    Waves are an omnipresent feature in heliophysical plasmas. In particular, transverse (or "Alfvénic") waves have been observed at a wide range of spatial and temporal scales within the corona and solar wind. These waves play a key role in transporting energy through the solar atmosphere and are also thought to contribute to the heating and acceleration of the solar wind. Previous studies of low-frequency (automated detection and measurement of low-frequency transverse waves with over 7 years of SDO / AIA data to provide a detailed picture of coronal transverse waves in polar plumes and, for the first time, begin to examine their long-term behaviour. We measure waves at three different heights in each of eight, four-hour periods spanning May 2010 - May 2017. We find that the bulk wave parameters within these 24 regions are largely consistent over most of a solar cycle. However, there is some evidence for smaller-scale variations both with height and over time periods of a few years. We also discuss total energy flux estimations based on the full wave power spectra, which yields a more nuanced picture than previous values based on summary statistics. Overall, this work expands our view of wave processes in the corona and is relevant to both theoretical and modelling considerations of energy transport within the solar atmosphere. Crucially, these initial results suggest that the energy flux provided by the low-frequency transverse waves varies little over the solar cycle, potentially indicating that the waves provide a consistent source of energy to the corona and beyond.

  1. Lockheed Solar Observatory and the Discovery of Moreton-Ramsey Waves

    Science.gov (United States)

    Tarbell, Theodore D.

    2014-06-01

    Moreton Waves are high-speed disturbances seen traveling away from large solar flares in H-alpha movies of the solar chromosphere. They were discovered by the observer Harry Ramsey in the late 1950s, and then published and publicized by the director Gail Moreton, both of the Lockheed Solar Observatory in the Hollywood Hills of Southern California. These efforts established the scientific reputation and secured continuing funding of the observatory, whose present-day successor is the Lockheed Martin Solar and Astrophysics Lab in Palo Alto. Moreton waves are rare, and there was limited interest in them until the EIT instrument on SOHO began seeing large numbers of similar waves in the corona in the late 1990s. The exact relation between the two observations is still a research topic today. This talk will describe some of the history of the observatory and the discovery and early interpretation of the waves.

  2. Gravitational Waves versus X and Gamma Ray Emission in a Short Gamma-Ray Burst

    OpenAIRE

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, Remo

    2012-01-01

    The recent progress in the understanding the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst, GRB 090227B, allows to give an estimate of the gravitational waves versus the X and Gamma-ray emission in a short gamma-ray burst.

  3. Solar assisted heat pumps: A possible wave of the future

    Science.gov (United States)

    Smetana, F. O.

    1976-01-01

    With the higher costs of electric power and the widespread interest to use solar energy to reduce the national dependence on fossil fuels, heat pumps are examined to determine their suitability for use with solar energy systems.

  4. SOLAR ENERGY AND ITS APPLICATIONS IN NIGERIA: Short ...

    African Journals Online (AJOL)

    ... make to our lives and economy, most especially during this time of erratic power supply by the National Electric Power Authority (NEPA). Some of the applications of solar energy in Nigeria are in Village electrification, residential / commercial building, water pumping and purification, agricultural utilization, heating sources, ...

  5. Gradient pattern analysis of short solar radio bursts

    Czech Academy of Sciences Publication Activity Database

    Rosa, R. R.; Karlický, Marian; Veronese, T.B.; Vijaykumar, N. L.; Sawant, H. S.; Borgazzi, A. I.; Dantas, M. S.; Barbosa, E. M. B.; Sych, R.A.; Mendes, O.

    2008-01-01

    Roč. 42, č. 5 (2008), s. 844-851 ISSN 0273-1177 Institutional research plan: CEZ:AV0Z10030501 Keywords : solar radio bursts * stochastic processes * wavelets Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.860, year: 2008

  6. ULF Wave Activity in the Magnetosphere: Resolving Solar Wind Interdependencies to Identify Driving Mechanisms

    Science.gov (United States)

    Bentley, S. N.; Watt, C. E. J.; Owens, M. J.; Rae, I. J.

    2018-04-01

    Ultralow frequency (ULF) waves in the magnetosphere are involved in the energization and transport of radiation belt particles and are strongly driven by the external solar wind. However, the interdependency of solar wind parameters and the variety of solar wind-magnetosphere coupling processes make it difficult to distinguish the effect of individual processes and to predict magnetospheric wave power using solar wind properties. We examine 15 years of dayside ground-based measurements at a single representative frequency (2.5 mHz) and a single magnetic latitude (corresponding to L ˜ 6.6RE). We determine the relative contribution to ULF wave power from instantaneous nonderived solar wind parameters, accounting for their interdependencies. The most influential parameters for ground-based ULF wave power are solar wind speed vsw, southward interplanetary magnetic field component Bzstill account for significant amounts of power. We suggest that these three parameters correspond to driving by the Kelvin-Helmholtz instability, formation, and/or propagation of flux transfer events and density perturbations from solar wind structures sweeping past the Earth. We anticipate that this new parameter reduction will aid comparisons of ULF generation mechanisms between magnetospheric sectors and will enable more sophisticated empirical models predicting magnetospheric ULF power using external solar wind driving parameters.

  7. Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters

    DEFF Research Database (Denmark)

    Tedd, James; Frigaard, Peter

    2007-01-01

    This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived...... experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient...... to allow advanced control systems to be developed using this knowledge to significantly improve power capture....

  8. Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters

    Energy Technology Data Exchange (ETDEWEB)

    Tedd, J.; Frigaard, P. [Department of Civil Engineering, Aalborg University, Aalborg (Denmark)

    2007-07-01

    This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient to allow advanced control systems to be developed using this knowledge to significantly improve power capture.

  9. Sun glitter imaging of submarine sand waves on the Taiwan Banks: Determination of the relaxation rate of short waves

    Science.gov (United States)

    Shao, Hao; Li, Yan; Li, Li

    2011-06-01

    Above sand waves on the seafloor, surface short waves, which are responsible for the radiance distribution in remote sensing imagery, are modulated gradually by the submarine topography. The relaxation rate μr characterizes the rate at which the short waves reach their saturation range after being disturbed. It is a key parameter in the weak hydrodynamic interaction theory and is also a most important parameter in the imaging mechanism used for mapping submarine bottom topography. In this study, a robust expression containing intensity and phase (advection effect) modulations of the perturbed action spectrum of short waves was deduced, by using the first-order weak hydrodynamic interaction theory. On the basis of the phase modulation, a method was developed to determine the relaxation rate in the Sun glitter imaging mechanism. The relaxation rates were estimated using in situ data measured on a cruise over the sand waves of the Taiwan Banks, a sea area between the East China Sea and the South China Sea, on 28-29 August 2006. Results showed that, under a wind speed of 5.0 m s-1, the relaxation rate of short waves was about 0.055 s-1 in response to current variations and about 0.025 s-1 equivalently in response to sea bottom topographic variations. The former value could be applied to interpret the amplitude of submarine topography by using satellite imagery, while the latter one (equivalent relaxation rate μ'r) could help to more accurately calibrate the spatial position of the retrieved sea bottom topography.

  10. New Insight into Short-Wavelength Solar Wind Fluctuations from Vlasov Theory

    Science.gov (United States)

    Sahraoui, Fouad; Belmont, G.; Goldstein, M. L.

    2012-01-01

    The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations gave evidence of the dominance of kinetic Alfven waves (KAWs) at sub-ion scales with omega omega (sub ci)) is more relevant. Here, we study key properties of the short-wavelength plasma modes under limited, but realistic, SW conditions, Typically Beta(sub i) approx. > Beta (sub e) 1 and for high oblique angles of propagation 80 deg theory, we discuss the relevance of each plasma mode (fast, Bernstein, KAW, whistler) in carrying the energy cascade down to electron scales. We show, in particular, that the shear Alfven mode (known in the magnetohydrodynamic limit) extends at scales kappa rho (sub i) approx. > 1 to frequencies either larger or smaller than omega (sub ci), depending on the anisotropy kappa (parallel )/ kappa(perpendicular). This extension into small scales is more readily called whistler (omega > omega (sub ci)) or KAW (omega < omega (sub ci)) although the mode is essentially the same. This contrasts with the well-accepted idea that the whistler branch always develops as a continuation at high frequencies of the fast magnetosonic mode. We show, furthermore, that the whistler branch is more damped than the KAW one, which makes the latter the more relevant candidate to carry the energy cascade down to electron scales. We discuss how these new findings may facilitate resolution of the controversy concerning the nature of the small-scale turbulence, and we discuss the implications for present and future spacecraft wave measurements in the SW.

  11. MAGNETIC ROSSBY WAVES IN THE SOLAR TACHOCLINE AND RIEGER-TYPE PERIODICITIES

    International Nuclear Information System (INIS)

    Zaqarashvili, Teimuraz V.; Carbonell, Marc; Oliver, Ramon; Ballester, Jose Luis

    2010-01-01

    Apart from the eleven-year solar cycle, another periodicity around 155-160 days was discovered during solar cycle 21 in high-energy solar flares, and its presence in sunspot areas and strong magnetic flux has been also reported. This periodicity has an elusive and enigmatic character, since it usually appears only near the maxima of solar cycles, and seems to be related with a periodic emergence of strong magnetic flux at the solar surface. Therefore, it is probably connected with the tachocline, a thin layer located near the base of the solar convection zone, where a strong dynamo magnetic field is stored. We study the dynamics of Rossby waves in the tachocline in the presence of a toroidal magnetic field and latitudinal differential rotation. Our analysis shows that the magnetic Rossby waves are generally unstable and that the growth rates are sensitive to the magnetic field strength and to the latitudinal differential rotation parameters. Variation of the differential rotation and the magnetic field strength throughout the solar cycle enhance the growth rate of a particular harmonic in the upper part of the tachocline around the maximum of the solar cycle. This harmonic is symmetric with respect to the equator and has a period of 155-160 days. A rapid increase of the wave amplitude could give rise to a magnetic flux emergence leading to observed periodicities in solar activity indicators related to magnetic flux.

  12. Statistical study of waves distribution in the inner magnetosphere using geomagnetic indices and solar wind parameters

    Science.gov (United States)

    Aryan, H.; Yearby, K.; Balikhin, M. A.; Krasnoselskikh, V.; Agapitov, O. V.

    2013-12-01

    The interaction of gyroresonant wave particles with chorus waves largely determine the dynamics of the Earth's radiation belts that effects the acceleration and loss of radiation belt electrons. The common approach is to present model waves distribution in the inner magnetosphere under different values of geomagnetic activity as expressed by the geomagnetic indices. However it is known that solar wind parameters such as bulk velocity (V) and density (n) are more effective in the control of high energy fluxes at the geostationary orbit. Therefore in the present study the set of parameters of the wave distribution is expanded to include the solar wind parameters in addition to the geomagnetic indices. The present study examines almost four years (01, January, 2004 to 29, September, 2007) of Cluster STAFF-SA, Double Star TC1 and OMNI data in order to present a combined model of wave magnetic field intensities for the chorus waves as a function of magnetic local time (MLT), L-shell (L*), geomagnetic activity, and solar wind velocity and density. Generally, the largest wave intensities are observed during average solar wind velocities (3006cm-3. On the other hand the wave intensity is lower and limited between 06:00 to 18:00 MLT for V700kms-1.

  13. Thermal and Driven Stochastic Growth of Langmuir Waves in the Solar Wind and Earth's Foreshock

    Science.gov (United States)

    Cairns, Iver H.; Robinson, P. A.; Anderson, R. R.

    2000-01-01

    Statistical distributions of Langmuir wave fields in the solar wind and the edge of Earth's foreshock are analyzed and compared with predictions for stochastic growth theory (SGT). SGT quantitatively explains the solar wind, edge, and deep foreshock data as pure thermal waves, driven thermal waves subject to net linear growth and stochastic effects, and as waves in a pure SGT state, respectively, plus radiation near the plasma frequency f(sub p). These changes are interpreted in terms of spatial variations in the beam instability's growth rate and evolution toward a pure SGT state. SGT analyses of field distributions are shown to provide a viable alternative to thermal noise spectroscopy for wave instruments with coarse frequency resolution, and to separate f(sub p) radiation from Langmuir waves.

  14. TRIGGERING COLLAPSE OF THE PRESOLAR DENSE CLOUD CORE AND INJECTING SHORT-LIVED RADIOISOTOPES WITH A SHOCK WAVE. II. VARIED SHOCK WAVE AND CLOUD CORE PARAMETERS

    Energy Technology Data Exchange (ETDEWEB)

    Boss, Alan P.; Keiser, Sandra A., E-mail: boss@dtm.ciw.edu, E-mail: keiser@dtm.ciw.edu [Department of Terrestrial Magnetism, Carnegie Institution, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

    2013-06-10

    A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of {approx}10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.

  15. Short-term solar irradiation forecasting based on Dynamic Harmonic Regression

    International Nuclear Information System (INIS)

    Trapero, Juan R.; Kourentzes, Nikolaos; Martin, A.

    2015-01-01

    Solar power generation is a crucial research area for countries that have high dependency on fossil energy sources and is gaining prominence with the current shift to renewable sources of energy. In order to integrate the electricity generated by solar energy into the grid, solar irradiation must be reasonably well forecasted, where deviations of the forecasted value from the actual measured value involve significant costs. The present paper proposes a univariate Dynamic Harmonic Regression model set up in a State Space framework for short-term (1–24 h) solar irradiation forecasting. Time series hourly aggregated as the Global Horizontal Irradiation and the Direct Normal Irradiation will be used to illustrate the proposed approach. This method provides a fast automatic identification and estimation procedure based on the frequency domain. Furthermore, the recursive algorithms applied offer adaptive predictions. The good forecasting performance is illustrated with solar irradiance measurements collected from ground-based weather stations located in Spain. The results show that the Dynamic Harmonic Regression achieves the lowest relative Root Mean Squared Error; about 30% and 47% for the Global and Direct irradiation components, respectively, for a forecast horizon of 24 h ahead. - Highlights: • Solar irradiation forecasts at short-term are required to operate solar power plants. • This paper assesses the Dynamic Harmonic Regression to forecast solar irradiation. • Models are evaluated using hourly GHI and DNI data collected in Spain. • The results show that forecasting accuracy is improved by using the model proposed

  16. Traveling wave interferometry particularly for solar power satellites

    International Nuclear Information System (INIS)

    Ott, J.H.; Rice, J.S.

    1983-01-01

    A method and apparatus are described for use in scientific measurement analysis and control. Travelling interference fringes are generated by radiating at least two different periodic waves at two different frequencies, one from each of two different radiators. The waves are received, mixed and filtered to detect at least one beat signal from these waves which represents the travelling interference fringe. The phase of that beat signal is detected relative to a reference signal of the same frequency as the beat signal. The radiated waves may be received at a second antenna and the phase of the beat of the waves at the first antenna is compared to the phase of the beat as observed at the second antenna. A third wave may be radiated from the first antenna to provide a reference signal which is the beat generated by the third wave and the other wave from the same radiator

  17. Maximizing the short circuit current of organic solar cells by partial decoupling of electrical and optical properties

    Science.gov (United States)

    Qarony, Wayesh; Hossain, Mohammad I.; Jovanov, Vladislav; Knipp, Dietmar; Tsang, Yuen Hong

    2018-03-01

    The partial decoupling of electronic and optical properties of organic solar cells allows for realizing solar cells with increased short circuit current and energy conversion efficiency. The proposed device consists of an organic solar cell conformally prepared on the surface of an array of single and double textured pyramids. The device geometry allows for increasing the optical thickness of the organic solar cell, while the electrical thickness is equal to the nominal thickness of the solar cell. By increasing the optical thickness of the solar cell, the short circuit current is distinctly increased. The quantum efficiency and short circuit current are determined using finite-difference time-domain simulations of the 3D solar cell structure. The influence of different solar cell designs on the quantum efficiency and short circuit current is discussed and optimal device dimensions are proposed.

  18. Multicomponent long-wave-short-wave resonance interaction system: Bright solitons, energy-sharing collisions, and resonant solitons.

    Science.gov (United States)

    Sakkaravarthi, K; Kanna, T; Vijayajayanthi, M; Lakshmanan, M

    2014-11-01

    We consider a general multicomponent (2+1)-dimensional long-wave-short-wave resonance interaction (LSRI) system with arbitrary nonlinearity coefficients, which describes the nonlinear resonance interaction of multiple short waves with a long wave in two spatial dimensions. The general multicomponent LSRI system is shown to be integrable by performing the Painlevé analysis. Then we construct the exact bright multisoliton solutions by applying the Hirota's bilinearization method and study the propagation and collision dynamics of bright solitons in detail. Particularly, we investigate the head-on and overtaking collisions of bright solitons and explore two types of energy-sharing collisions as well as standard elastic collision. We have also corroborated the obtained analytical one-soliton solution by direct numerical simulation. Also, we discuss the formation and dynamics of resonant solitons. Interestingly, we demonstrate the formation of resonant solitons admitting breather-like (localized periodic pulse train) structure and also large amplitude localized structures akin to rogue waves coexisting with solitons. For completeness, we have also obtained dark one- and two-soliton solutions and studied their dynamics briefly.

  19. Characteristics of coronal shock waves and solar type 2 radio bursts

    Science.gov (United States)

    Mann, G.; Classen, H.-T.

    1995-01-01

    In the solar corona shock waves generated by flares and/or coronal mass ejections can be observed by radio astronomical methods in terms of solar type 2 radio bursts. In dynamic radio spectra they appear as emission stripes slowly drifting from high to low frequencies. A sample of 25 solar type 2 radio bursts observed in the range of 40 - 170 MHz with a time resolution of 0.1 s by the new radiospectrograph of the Astrophvsikalisches Institut Potsdam in Tremsdorf is statistically investigated concerning their spectral features, i.e, drift rate, instantaneous bandwidth, and fundamental harmonic ratio. In-situ plasma wave measurements at interplanetary shocks provide the assumption that type 2 radio radiation is emitted in the vicinity of the transition region of shock waves. Thus, the instantaneous bandwidth of a solar type 2 radio burst would reflect the density jump across the associated shock wave. Comparing the inspection of the Rankine-Hugoniot relations of shock waves under coronal circumstances with those obtained from the observational study, solar type 2 radio bursts should be regarded to be generated by weak supercritical, quasi-parallel, fast magnetosonic shock waves in the corona.

  20. NONLINEAR DYNAMICS OF MAGNETOHYDRODYNAMIC ROSSBY WAVES AND THE CYCLIC NATURE OF SOLAR MAGNETIC ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Raphaldini, Breno; Raupp, Carlos F. M., E-mail: brenorfs@gmail.com, E-mail: carlos.raupp@iag.usp.br [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Departamento de Geofísica, Rua do Matão, 1226-Cidade Universitária São Paulo-SP 05508-090 (Brazil)

    2015-01-20

    The solar dynamo is known to be associated with several periodicities, with the nearly 11/22 yr cycle being the most pronounced one. Even though these quasiperiodic variations of solar activity have been attributed to the underlying dynamo action in the Sun's interior, a fundamental theoretical description of these cycles is still elusive. Here, we present a new possible direction in understanding the Sun's cycles based on resonant nonlinear interactions among magnetohydrodynamic (MHD) Rossby waves. The WKB theory for dispersive waves is applied to magnetohydrodynamic shallow-water equations describing the dynamics of the solar tachocline, and the reduced dynamics of a resonant triad composed of MHD Rossby waves embedded in constant toroidal magnetic field is analyzed. In the conservative case, the wave amplitudes evolve periodically in time, with periods on the order of the dominant solar activity timescale (∼11 yr). In addition, the presence of linear forcings representative of either convection or instabilities of meridionally varying background states appears to be crucial in balancing dissipation and thus sustaining the periodic oscillations of wave amplitudes associated with resonant triad interactions. Examination of the linear theory of MHD Rossby waves embedded in a latitudinally varying mean flow demonstrates that MHD Rossby waves propagate toward the equator in a waveguide from –35° to 35° in latitude, showing a remarkable resemblance to the structure of the butterfly diagram of the solar activity. Therefore, we argue that resonant nonlinear magnetohydrodynamic Rossby wave interactions might significantly contribute to the observed cycles of magnetic solar activity.

  1. Short time propagation of a singular wave function: Some surprising results

    Science.gov (United States)

    Marchewka, A.; Granot, E.; Schuss, Z.

    2007-08-01

    The Schrödinger evolution of an initially singular wave function was investigated. First it was shown that a wide range of physical problems can be described by initially singular wave function. Then it was demonstrated that outside the support of the initial wave function the time evolution is governed to leading order by the values of the wave function and its derivatives at the singular points. Short-time universality appears where it depends only on a single parameter—the value at the singular point (not even on its derivatives). It was also demonstrated that the short-time evolution in the presence of an absorptive potential is different than in the presence of a nonabsorptive one. Therefore, this dynamics can be harnessed to the determination whether a potential is absorptive or not simply by measuring only the transmitted particles density.

  2. Dynamical evolution of short-wave instability in LHD

    International Nuclear Information System (INIS)

    Miura, H.; Nakajima, N.

    2009-01-01

    Full text: Dynamical growth of ballooning modes with high poloidal(m) /toroidal(n) Fourier coefficients (higher m/n modes) in the Large Helical Device (LHD) is studied by means of full 3D nonlinear simulations. Influences of higher modes on low modes are studied numerically. In the LHD experiments, some MHD activities are observed but the activities do not bring about serious deteriorations of plasma profiles and high beta-values have been achieved. For the sake of understanding the mild saturation of the instability, some numerical simulations have been carried out. However, the earlier works focus on low modes and dynamical behaviors of high modes are not understood well. In order to understand the dynamical evolution of the pressure-driven high-modes and clarify their influences on growth of low-modes, full-3D simulations of high Reynolds number LHD plasma are carried out for the magnetic field with the vacuum magnetic axis position 3.6m, the peak beta value 3.7%, and the reference Reynolds number Re=10 6 . In the simulations, the growth of ballooning modes up to n=15 toroidal wave-number is identified. The simultaneous growth of multiple ballooning modes brings about total modification of the pressure profile, showing that the pressure-flattening mechanism can not suppress the growth of the modes. On the other hand, a mild saturation of the unstable mode is obtained in another simulation with the relatively large parallel heat conduction, suggesting that the mild saturations might be rather contributed by the dissipative effects (typically by the parallel heat conduction) than the nonlinear mechanism such as the modifications of the pressure profiles. We also find that the wave-length of the n=15 ballooning mode is comparable to the ion skin-depth, suggesting the necessity of studying the high modes in the framework of the Hall-MHD dynamics. Studying the dynamics of the LHD plasmas by the use of the Hall-MHD or some sort of the two-fluid system is considered

  3. Heat wave propagation in a thin film irradiated by ultra-short laser pulses

    International Nuclear Information System (INIS)

    Yoo, Jae Gwon; Kim, Cheol Jung; Lim, C. H.

    2004-01-01

    A thermal wave solution of a hyperbolic heat conduction equation in a thin film is developed on the basis of the Green's function formalism. Numerical computations are carried out to investigate the temperature response and the propagation of the thermal wave inside a thin film due to a heat pulse generated by ultra-short laser pulses with various laser pulse durations and thickness of the film

  4. Development of processing procedures for advanced silicon solar cells. [antireflection coatings and short circuit currents

    Science.gov (United States)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1975-01-01

    Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing.

  5. Langmuir wave-packet generation from an electron beam propagating in the inhomogeneous solar wind

    International Nuclear Information System (INIS)

    Zaslavsky, A.; Maksimovic, M.; Volokitin, A. S.; Krasnoselskikh, V. V.; Bale, S. D.

    2010-01-01

    Recent in-situ observations by the TDS instrument equipping the STEREO spacecraft revealed that large amplitude spatially localized Langmuir waves are frequent in the solar wind, and correlated with the presence of suprathermal electron beams during type III events or close to the electron foreshock. We briefly present the new theoretical model used to perform the study of these localized electrostatic waves, and show first results of simulations of the destabilization of Langmuir waves by a beam propagating in the inhomogeneous solar wind. The main results are that the destabilized waves are mainly focalized near the minima of the density profiles, and that the nonlinear interaction of the waves with the resonant particles enhances this focalization compared to a situation in which the only propagation effects are taken into account.

  6. Three-dimensional Langmuir wave instabilities in type III solar radio bursts

    International Nuclear Information System (INIS)

    Bardwell, S.; Goldman, M.V.

    1976-01-01

    Assuming that type III solar radio bursts are associated with electron streams moving at about c/3, Langmuir waves should be strongly excited. We have studied all of the Langmuir-wave linear parametric instabilities excited in cylindrical symmetry by an electron-stream--driven Langmuir wave-pump propagating along the stream axis. Included in this unified homogeneous treatment are induced backscattering off ions, the oscillating two-stream instability, and a new ''stimulated modulational instability,'' previously unconsidered in this context. Near a few solar radii, the latter two deposit Langmuir wave energy into a forward-scattering cone about the stream axis. It is concluded that the linear stage of the forward-scattering instabilities involves transfer of energy to Langmuir waves which remain in resonance with the stream, and therefore probably do not prevent rapid depletion of the electron stream due to quasilinear plateau formation at these distances from the Sun

  7. Some observations on stray magnetic fields and power outputs from short-wave diathermy equipment

    Energy Technology Data Exchange (ETDEWEB)

    Lau, R.W.M.; Dunscombe, P.B.

    1984-04-01

    Recent years have seen increasing interest in the possible hazards arising from the use of nonionizing electromagnetic radiation. Relatively large and potentially hazardous fields are to be found in the vicinity of short-wave and microwave equipment used in physiotherapy departments to produce therapeutic temperature rises. This note reports the results of measurements of the stray magnetic field and power output of a conventional short-wave diathermy unit when applied to tissue-equivalent phantoms. The dependence of these quantities on the variables, i.e. power setting of the unit, capacitor plate size, phantom size and phantom-capacitor plate separation, are discussed.

  8. Global-scale equatorial Rossby waves as an essential component of solar internal dynamics

    Science.gov (United States)

    Löptien, Björn; Gizon, Laurent; Birch, Aaron C.; Schou, Jesper; Proxauf, Bastian; Duvall, Thomas L.; Bogart, Richard S.; Christensen, Ulrich R.

    2018-05-01

    The Sun’s complex dynamics is controlled by buoyancy and rotation in the convection zone. Large-scale flows are dominated by vortical motions1 and appear to be weaker than expected in the solar interior2. One possibility is that waves of vorticity due to the Coriolis force, known as Rossby waves3 or r modes4, remove energy from convection at the largest scales5. However, the presence of these waves in the Sun is still debated. Here, we unambiguously discover and characterize retrograde-propagating vorticity waves in the shallow subsurface layers of the Sun at azimuthal wavenumbers below 15, with the dispersion relation of textbook sectoral Rossby waves. The waves have lifetimes of several months, well-defined mode frequencies below twice the solar rotational frequency, and eigenfunctions of vorticity that peak at the equator. Rossby waves have nearly as much vorticity as the convection at the same scales, thus they are an essential component of solar dynamics. We observe a transition from turbulence-like to wave-like dynamics around the Rhines scale6 of angular wavenumber of approximately 20. This transition might provide an explanation for the puzzling deficit of kinetic energy at the largest spatial scales.

  9. Low frequency wave sources in the outer magnetosphere, magnetosheath, and near Earth solar wind

    Directory of Open Access Journals (Sweden)

    O. D. Constantinescu

    2007-11-01

    Full Text Available The interaction of the solar wind with the Earth magnetosphere generates a broad variety of plasma waves through different mechanisms. The four Cluster spacecraft allow one to determine the regions where these waves are generated and their propagation directions. One of the tools which takes full advantage of the multi-point capabilities of the Cluster mission is the wave telescope technique which provides the wave vector using a plane wave representation. In order to determine the distance to the wave sources, the source locator – a generalization of the wave telescope to spherical waves – has been recently developed. We are applying the source locator to magnetic field data from a typical traversal of Cluster from the cusp region and the outer magnetosphere into the magnetosheath and the near Earth solar wind. We find a high concentration of low frequency wave sources in the electron foreshock and in the cusp region. To a lower extent, low frequency wave sources are also found in other magnetospheric regions.

  10. Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects

    Energy Technology Data Exchange (ETDEWEB)

    Vigeesh, G.; Steiner, O. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg (Germany); Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de [New Mexico State University, Department of Astronomy, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003 (United States)

    2017-02-01

    Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in the Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.

  11. Mode Conversion of a Solar Extreme-ultraviolet Wave over a Coronal Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Zong, Weiguo [Key Laboratory of Space Weather, National Center for Space Weather, China Meteorological Administration, Beijing 100081 (China); Dai, Yu, E-mail: ydai@nju.edu.cn [Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210023 (China)

    2017-01-10

    We report on observations of an extreme-ultraviolet (EUV) wave event in the Sun on 2011 January 13 by Solar Terrestrial Relations Observatory and Solar Dynamics Observatory in quadrature. Both the trailing edge and the leading edge of the EUV wave front in the north direction are reliably traced, revealing generally compatible propagation velocities in both perspectives and a velocity ratio of about 1/3. When the wave front encounters a coronal cavity near the northern polar coronal hole, the trailing edge of the front stops while its leading edge just shows a small gap and extends over the cavity, meanwhile getting significantly decelerated but intensified. We propose that the trailing edge and the leading edge of the northward propagating wave front correspond to a non-wave coronal mass ejection component and a fast-mode magnetohydrodynamic wave component, respectively. The interaction of the fast-mode wave and the coronal cavity may involve a mode conversion process, through which part of the fast-mode wave is converted to a slow-mode wave that is trapped along the magnetic field lines. This scenario can reasonably account for the unusual behavior of the wave front over the coronal cavity.

  12. The influence of scrotonin on survival of Candida guillermondii, irradiated by short-wave ultraviolet

    International Nuclear Information System (INIS)

    Strakhovskaya, M.G.; Frajkin, G.Ya.; Goncharenko, E.N.

    1982-01-01

    A study was made on the influence of serotonin on survival of Candida quilliermondu yeast irradiated by 254 nm short-wave ultraviolet. It was established that incubation with serotonin, leading to its penetration inside cells causes two opposite effects - protection from ultraviolet inactivation in preliminary incubation and intensification of cells death in postradiation incubation. Serotonin action is similar to the effects induced in C. guillermondii yeast by 334 nm long-wave ultraviolet light, that is serotonin possesses photomimetic effect. The data obtained are considered as conformaition of participation of serotonin photoinduced synthesis in manifestation of effects of long-wave ultraviolet light action on yeast

  13. Generic short-time propagation of sharp-boundaries wave packets

    Science.gov (United States)

    Granot, E.; Marchewka, A.

    2005-11-01

    A general solution to the "shutter" problem is presented. The propagation of an arbitrary initially bounded wave function is investigated, and the general solution for any such function is formulated. It is shown that the exact solution can be written as an expression that depends only on the values of the function (and its derivatives) at the boundaries. In particular, it is shown that at short times (t << 2mx2/hbar, where x is the distance to the boundaries) the wave function propagation depends only on the wave function's values (or its derivatives) at the boundaries of the region. Finally, we generalize these findings to a non-singular wave function (i.e., for wave packets with finite-width boundaries) and suggest an experimental verification.

  14. The distribution of waves in the inner magnetosphere as a function of solar wind parameters

    Science.gov (United States)

    Aryan, Homayon; Balikhin, Michael A.; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Yearby, Keith

    Energetic electrons within the Earth’s radiation belts represent a serious hazard to geostationary satellites. The interactions of electrons with chorus waves play an important role in both the acceleration and loss of radiation belt electrons. Studies of the evolution of energetic electron fluxes rely heavily on numerical codes in order to model energy and pitch angle diffusion due to electron interaction with plasma waves in the frame of quasilinear approximation. Application of these codes requires knowledge of statistical wave models to present wave distributions in the magnetosphere. A number of such models are based on CRESS, Cluster, THEMIS and other mission data. These models present wave distributions as a function of L-shell, magnetic local time, magnetic latitude and geomagnetic activity expressed by geomagnetic indices (Kp or Ae). However, it has been shown by G. Reeves and co-authors that only 50% of geomagnetic storms increase flux of relativistic electrons at GEO while 20% cause a decrease. This emphasizes the importance of including solar wind parameters in addition to geomagnetic indices. The present study examines almost four years (01, January, 2004 to 29, September, 2007) of STAFF (Spatio-Temporal Analysis of Field Fluctuation) data from Double Star TC1 combined with geomagnetic indices and solar wind parameters from OMNI database in order to present a comprehensive model of chorus wave intensities as a function of L-shell, magnetic local time, magnetic latitude, geomagnetic indices and solar wind parameters. The results show that chorus emission is not only sub-storm dependent but also dependent upon solar wind parameters with solar wind velocity evidently the most influential solar wind parameter. The largest peak intensities are observed for lower band chorus during active conditions, high solar wind velocity, low density and high pressure.

  15. Statistical study of chorus wave distributions in the inner magnetosphere using Ae and solar wind parameters

    Science.gov (United States)

    Aryan, Homayon; Yearby, Keith; Balikhin, Michael; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Boynton, Richard

    2014-08-01

    Energetic electrons within the Earth's radiation belts represent a serious hazard to geostationary satellites. The interactions of electrons with chorus waves play an important role in both the acceleration and loss of radiation belt electrons. The common approach is to present model wave distributions in the inner magnetosphere under different values of geomagnetic activity as expressed by the geomagnetic indices. However, it has been shown that only around 50% of geomagnetic storms increase flux of relativistic electrons at geostationary orbit while 20% causes a decrease and the remaining 30% has relatively no effect. This emphasizes the importance of including solar wind parameters such as bulk velocity (V), density (n), flow pressure (P), and the vertical interplanetary magnetic field component (Bz) that are known to be predominately effective in the control of high energy fluxes at the geostationary orbit. Therefore, in the present study the set of parameters of the wave distributions is expanded to include the solar wind parameters in addition to the geomagnetic activity. The present study examines almost 4 years (1 January 2004 to 29 September 2007) of Spatio-Temporal Analysis of Field Fluctuation data from Double Star TC1 combined with geomagnetic indices and solar wind parameters from OMNI database in order to present a comprehensive model of wave magnetic field intensities for the chorus waves as a function of magnetic local time, L shell (L), magnetic latitude (λm), geomagnetic activity, and solar wind parameters. Generally, the results indicate that the intensity of chorus emission is not only dependent upon geomagnetic activity but also dependent on solar wind parameters with velocity and southward interplanetary magnetic field Bs (Bz < 0), evidently the most influential solar wind parameters. The largest peak chorus intensities in the order of 50 pT are observed during active conditions, high solar wind velocities, low solar wind densities, high

  16. The Ion Acoustic Solitary Waves and Double Layers in the Solar Wind Plasma

    Directory of Open Access Journals (Sweden)

    C. R. Choi

    2006-09-01

    Full Text Available Ion acoustic solitary wave in a plasma consisting of electrons and ions with an external magnetic field is reinvestigated using the Sagdeev's potential method. Although the Sagdeev potential has a singularity for n<1, where n is the ion number density, we obtain new solitary wave solutions by expanding the Sagdeev potential up to δ n^4 near n=1. They are compressiv (rarefactive waves and shock type solitary waves. These waves can exist all together as a superposed wave which may be used to explain what would be observed in the solar wind plasma. We compared our theoretical results with the data of the Freja satellite in the study of Wu et al.(1996. Also it is shown that these solitary waves propagate with a subsonic speed.

  17. A triggering of solar flare by magnetosonic waves in a neutral sheet plasma

    International Nuclear Information System (INIS)

    Sakai, Jun-ichi; Washimi, Haruichi.

    1981-09-01

    A theoretical model of the triggering of a solar flare by magnetosonic waves in a neutral sheet plasma is discussed. It is shown that the ponderomotive force due to the magnetosonic waves strongly excites the plasma convection flow in the magnetic neutral sheet which in turn enhances the tearing instability. The system of basic equations for the tearing mode including the time-averaged nonlinear effects due to the magnetosonic waves is derived and the boundary value problem is solved. The results show that the growth time of the instability is shortened to about 100 sec for reasonable magnetosonic wave intensity. (author)

  18. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    Science.gov (United States)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  19. Stochastic Short-term High-resolution Prediction of Solar Irradiance and Photovoltaic Power Output

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M. [ORNL; Olama, Mohammed M. [ORNL; Dong, Jin [ORNL; Djouadi, Seddik M. [ORNL; Zhang, Yichen [University of Tennessee, Knoxville (UTK), Department of Electrical Engineering and Computer Science

    2017-09-01

    The increased penetration of solar photovoltaic (PV) energy sources into electric grids has increased the need for accurate modeling and prediction of solar irradiance and power production. Existing modeling and prediction techniques focus on long-term low-resolution prediction over minutes to years. This paper examines the stochastic modeling and short-term high-resolution prediction of solar irradiance and PV power output. We propose a stochastic state-space model to characterize the behaviors of solar irradiance and PV power output. This prediction model is suitable for the development of optimal power controllers for PV sources. A filter-based expectation-maximization and Kalman filtering mechanism is employed to estimate the parameters and states in the state-space model. The mechanism results in a finite dimensional filter which only uses the first and second order statistics. The structure of the scheme contributes to a direct prediction of the solar irradiance and PV power output without any linearization process or simplifying assumptions of the signal’s model. This enables the system to accurately predict small as well as large fluctuations of the solar signals. The mechanism is recursive allowing the solar irradiance and PV power to be predicted online from measurements. The mechanism is tested using solar irradiance and PV power measurement data collected locally in our lab.

  20. Multi-wavelength Observations of Solar Acoustic Waves Near Active Regions

    Science.gov (United States)

    Monsue, Teresa; Pesnell, Dean; Hill, Frank

    2018-01-01

    Active region areas on the Sun are abundant with a variety of waves that are both acoustically helioseismic and magnetohydrodynamic in nature. The occurrence of a solar flare can disrupt these waves, through MHD mode-mixing or scattering by the excitation of these waves. We take a multi-wavelength observational approach to understand the source of theses waves by studying active regions where flaring activity occurs. Our approach is to search for signals within a time series of images using a Fast Fourier Transform (FFT) algorithm, by producing multi-frequency power map movies. We study active regions both spatially and temporally and correlate this method over multiple wavelengths using data from NASA’s Solar Dynamics Observatory. By surveying the active regions on multiple wavelengths we are able to observe the behavior of these waves within the Solar atmosphere, from the photosphere up through the corona. We are able to detect enhancements of power around active regions, which could be acoustic power halos and of an MHD-wave propagating outward by the flaring event. We are in the initial stages of this study understanding the behaviors of these waves and could one day contribute to understanding the mechanism responsible for their formation; that has not yet been explained.

  1. Hall-magnetohydrodynamic waves in flowing ideal incompressible solar-wind plasmas

    International Nuclear Information System (INIS)

    Zhelyazkov, I

    2010-01-01

    It is well established now that the solar atmosphere, from the photosphere to the corona and the solar wind, is a highly structured medium. Satellite observations have confirmed the presence of steady flows there. Here, we investigate the propagation of magnetohydrodynamic (MHD) eigenmodes (kink and sausage surface waves) travelling along an ideal incompressible flowing plasma cylinder (flux tube) surrounded by a flowing plasma environment in the framework of the Hall magnetohydrodynamics. The propagation characteristics of the waves are studied in a reference frame moving with the mass flow outside the tube. In general, the flows change the waves' phase velocities compared with their magnitudes in a static MHD flux tube and the Hall effect extends the number of the possible wave dispersion curves. It turns out that while the kink waves, considered in the context of the standard magnetohydrodynamics, are unstable against the Kelvin-Helmholtz instability, they become stable when the Hall term in the generalized Ohm's law is taken into account. The sausage waves are stable in both considerations. All results concerning the waves' propagation and their stability/instability status are obtained on the basis of the linearized Hall-magnetohydrodynamic equations and are applicable mainly to the solar wind plasmas.

  2. Resonators for magnetohydrodynamic waves in the solar corona: radioemission modulation effect

    International Nuclear Information System (INIS)

    Zajtsev, V.V.; Stepanov, A.V.

    1982-01-01

    Data on type 2 solar radio bursts are analyzed in the framework of a model of radio emission production by shock waves. Type 2 solar radio bursts data are shown to suggest the existence of Alfven velocity minimum at a height of the one solar radius in the corona. The domain of a low Alfven velocity is a resonator for the fast magnetosonic waves. The eigenmodes of the resonator are determined. The main mode period is about a few minutes. Fast modes in the resonator can be amplified by energetic ion beams at the Cherenkov resonance. The modulation of meter solar radio emission with a period of about a few minutes can be explained by radiowave propagation through the MHD-resonator

  3. All-sky search for short gravitational-wave bursts in the first Advanced LIGO run

    NARCIS (Netherlands)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Phythian-Adams, A.T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.T.; Aguiar, O. D.; Aiello, L.; Ain, A.; Allen, B.; Allocca, A.; Altin, P. A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, R.D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Beer, C.; Bejger, M.; Belahcene, I.; Belgin, M.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, M.J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, A.L.S.; Bock, O.; Boer, M.; Bogaert, J.G.; Bohe, A.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, A.D.; Brown, D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderon; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglia, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Baiardi, L. Cerboni; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, D. S.; Charlton, P.; Chassande-Mottin, E.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y; Cheng, H. -P.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Qian; Chua, A. J. K.; Chua, S. E.; Chung, E.S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P. -F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, A.C.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, A.L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Costa, C. F. Da Silva; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Davis, D.; Daw, E. J.; Day, B.; Day, R.; De, S.; Debra, D.; Debreczeni, G.; Degallaix, J.; De laurentis, M.; Deleglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.A.; Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devenson, J.; Devine, R. C.; Dhurandhar, S.; Diaz, M. C.; Di Fiore, L.; Giovanni, M.G.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Alvarez, M. Dovale; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H. -B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Etienne, Z.; Etzel, T.; Evans, M.C.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.M.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Galiana, A. Fernandez; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M; Fong, H.; Forsyth, S. S.; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.P.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzalez, R.G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Lee-Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.M.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Buffoni-Hall, R.; Hall, E. D.; Hammond, G.L.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hanson, P.J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C. -J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.A.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J. -M.; Isi, M.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jimenez-Forteza, F.; Johnson, W.; Jones, I.D.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kandhasamy, S.; Kang, G.H.; Kanner, J. B.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kefelian, F.; Keitel, D.; Kelley, D. B.; Kennedy, R.E.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan., S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, Whansun; Kim, W.; Kim, Y.M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kirchhoff, R.; Kissel, J. S.; Klein, B.; Kleybolte, L.; Klimenko, S.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kraemer, H.C.; Kringel, V.; Krishnan, B.; Krolak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C.H.; Lee, K.H.; Lee, M.H.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Liu, J.; Lockerbie, N. A.; Lombardi, A. L.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lovelace, G.; Luck, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marka, S.; Marka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGrath Hoareau, C.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, F.A.; Miller, B.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B.C.; Moore, J.C.; Moraru, D.; Gutierrez Moreno, M.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, S.D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muniz, E. A. M.; Murray, P.G.; Mytidis, A.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nelemans, G.; Nelson, T. J. N.; Gutierrez-Neri, M.; Nery, M.; Neunzert, A.; Newport, J. M.; Newton-Howes, G.; Nguyen, T. T.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; Oelker, E.; Ogin, G. H.; Oh, J.; Oh, S. H.; Ohme, F.; Oliver, M. B.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.S; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Castro-Perez, J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Puerner, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Rhoades, E.; Ricci, F.; Riles, K.; Rizzo, D.M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romie, J. H.; Rosinska, D.; Rowan, S.; Ruediger, A.; Ruggi, P.; Ryan, K.A.; Sachdev, P.S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheuer, J.; Schmidt, E.; Schmidt, J; Schmidt, P.; Schnabel, R.B.; Schofield, R. M. S.; Schoenbeck, A.; Schreiber, K.E.C.; Schuette, D.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, M.S.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Setyawati, Y.; Shaddock, D. A.; Shaffer, T. J.; Shahriar, M. S.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, António Dias da; Singer, A; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J.R.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stevenson-Moore, P.; Stone, J.R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepanczyk, M. J.; Tacca, M.D.; Talukder, D.; Tanner, D. B.; Tapai, M.; Taracchini, A.; Taylor, W.R.; Theeg, T.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tippens, T.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tomlinson, C.; Tonelli, M.; Tornasi, Z.; Torrie, C. I.; Torya, D.; Travasso, F.; Traylor, G.; Trifiro, D.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tse, M.; Tso, R.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.G.; van den Brand, J. F. J.; Van Den Broeck, C.F.F.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasuth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P.J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Vicere, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, MT; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.M.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Williams, D.; Williams, D.R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Worden, J.; Wright, J.L.; Wu, D.S.; Wu, G.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrozny, A.; Zangrando, L.; Zanolin, M.; Zendri, J. -P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S.J.; Zhu, X. J.; Zucker, M. E.; Zweizig, J.

    2017-01-01

    We present the results from an all-sky search for short-duration gravitational waves in the data of the first run of the Advanced LIGO detectors between September 2015 and January 2016. The search algorithms use minimal assumptions on the signal morphology, so they are sensitive to a wide range of

  4. Short-period AM CVn systems as optical, X-ray and gravitational-wave sources

    NARCIS (Netherlands)

    Nelemans, G.; Yungelson, L.; Portegies Zwart, S.F.

    2004-01-01

    We model the population of AM CVn systems in the Galaxy and discuss the detectability of these systems with optical, X-ray and gravitational-wave detectors. We concentrate on the short-period (P < 1500 s) systems, some of which are expected to be in a phase of direct-impact accretion. Using a

  5. Laser induced non-monotonic degradation in short-circuit current of triple-junction solar cells

    Science.gov (United States)

    Dou, Peng-Cheng; Feng, Guo-Bin; Zhang, Jian-Min; Song, Ming-Ying; Zhang, Zhen; Li, Yun-Peng; Shi, Yu-Bin

    2018-06-01

    In order to study the continuous wave (CW) laser radiation effects and mechanism of GaInP/GaAs/Ge triple-junction solar cells (TJSCs), 1-on-1 mode irradiation experiments were carried out. It was found that the post-irradiation short circuit current (ISC) of the TJSCs initially decreased and then increased with increasing of irradiation laser power intensity. To explain this phenomenon, a theoretical model had been established and then verified by post-damage tests and equivalent circuit simulations. Conclusion was drawn that laser induced alterations in the surface reflection and shunt resistance were the main causes for the observed non-monotonic decrease in the ISC of the TJSCs.

  6. Observations of apparent superslow wave propagation in solar prominences

    Science.gov (United States)

    Raes, J. O.; Van Doorsselaere, T.; Baes, M.; Wright, A. N.

    2017-06-01

    Context. Phase mixing of standing continuum Alfvén waves and/or continuum slow waves in atmospheric magnetic structures such as coronal arcades can create the apparent effect of a wave propagating across the magnetic field. Aims: We observe a prominence with SDO/AIA on 2015 March 15 and find the presence of oscillatory motion. We aim to demonstrate that interpreting this motion as a magneto hydrodynamic (MHD) wave is faulty. We also connect the decrease of the apparent velocity over time with the phase mixing process, which depends on the curvature of the magnetic field lines. Methods: By measuring the displacement of the prominence at different heights to calculate the apparent velocity, we show that the propagation slows down over time, in accordance with the theoretical work of Kaneko et al. We also show that this propagation speed drops below what is to be expected for even slow MHD waves for those circumstances. We use a modified Kippenhahn-Schlüter prominence model to calculate the curvature of the magnetic field and fit our observations accordingly. Results: Measuring three of the apparent waves, we get apparent velocities of 14, 8, and 4 km s-1. Fitting a simple model for the magnetic field configuration, we obtain that the filament is located 103 Mm below the magnetic centre. We also obtain that the scale of the magnetic field strength in the vertical direction plays no role in the concept of apparent superslow waves and that the moment of excitation of the waves happened roughly one oscillation period before the end of the eruption that excited the oscillation. Conclusions: Some of the observed phase velocities are lower than expected for slow modes for the circumstances, showing that they rather fit with the concept of apparent superslow propagation. A fit with our magnetic field model allows for inferring the magnetic geometry of the prominence. The movie attached to Fig. 1 is available at http://www.aanda.org

  7. Modelling the short-circuit current of polymer bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Geens, Wim; Martens, Tom; Poortmans, Jef; Aernouts, Tom; Manca, Jean; Lutsen, Laurence; Heremans, Paul; Borghs, Staf; Mertens, Robert; Vanderzande, Dirk

    2004-01-01

    An analytical model has been developed to estimate the short-circuit current density of conjugated polymer/fullerene bulk heterojunction solar cells. The model takes into account the solvent-dependent molecular morphology of the donor/acceptor blend, which was revealed by transmission electron microscopy. Field-effect transistors based on single and composite organic layers were fabricated to determine values for the charge carrier mobilities of such films. These values served as input parameters of the model. It is shown that the difference in short-circuit current density that was measured between toluene-cast and chlorobenzene-cast conjugated polymer/fullerene photovoltaic cells (Appl. Phys. Lett. 78 (2001) 841) could be very well simulated with the model. Moreover, the calculations illustrate how increasing the hole and electron mobilities in the photoactive blend can improve the overall short-circuit current density of the solar cell

  8. On the excitation of ULF waves by solar wind pressure enhancements

    Directory of Open Access Journals (Sweden)

    P. T. I. Eriksson

    2006-11-01

    Full Text Available We study the onset and development of an ultra low frequency (ULF pulsation excited by a storm sudden commencement. On 30 August 2001, 14:10 UT, the Cluster spacecraft are located in the dayside magnetosphere and observe the excitation of a ULF pulsation by a threefold enhancement in the solar wind dynamic pressure. Two different harmonics are observed by Cluster, one at 6.8 mHz and another at 27 mHz. We observe a compressional wave and the development of a toroidal and poloidal standing wave mode. The toroidal mode is observed over a narrow range of L-shells whereas the poloidal mode is observed to have a much larger radial extent. By looking at the phase difference between the electric and magnetic fields we see that for the first two wave periods both the poloidal and toroidal mode are travelling waves and then suddenly change into standing waves. We estimate the azimuthal wave number for the 6.8 mHz to be m=10±3. For the 27 mHz wave, m seems to be several times larger and we discuss the implications of this. We conclude that the enhancement in solar wind pressure excites eigenmodes of the geomagnetic cavity/waveguide that propagate tailward and that these eigenmodes in turn couple to toroidal and poloidal mode waves. Thus our observations give firm support to the magnetospheric waveguide theory.

  9. Bottom boundary layer forced by finite amplitude long and short surface waves motions

    Science.gov (United States)

    Elsafty, H.; Lynett, P.

    2018-04-01

    A multiple-scale perturbation approach is implemented to solve the Navier-Stokes equations while including bottom boundary layer effects under a single wave and under two interacting waves. In this approach, fluid velocities and the pressure field are decomposed into two components: a potential component and a rotational component. In this study, the two components are exist throughout the entire water column and each is scaled with appropriate length and time scales. A one-way coupling between the two components is implemented. The potential component is assumed to be known analytically or numerically a prior, and the rotational component is forced by the potential component. Through order of magnitude analysis, it is found that the leading-order coupling between the two components occurs through the vertical convective acceleration. It is shown that this coupling plays an important role in the bottom boundary layer behavior. Its effect on the results is discussed for different wave-forcing conditions: purely harmonic forcing and impurely harmonic forcing. The approach is then applied to derive the governing equations for the bottom boundary layer developed under two interacting wave motions. Both motions-the shorter and the longer wave-are decomposed into two components, potential and rotational, as it is done in the single wave. Test cases are presented wherein two different wave forcings are simulated: (1) two periodic oscillatory motions and (2) short waves interacting with a solitary wave. The analysis of the two periodic motions indicates that nonlinear effects in the rotational solution may be significant even though nonlinear effects are negligible in the potential forcing. The local differences in the rotational velocity due to the nonlinear vertical convection coupling term are found to be on the order of 30% of the maximum boundary layer velocity for the cases simulated in this paper. This difference is expected to increase with the increase in wave

  10. Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

    Science.gov (United States)

    Bowen, Trevor A.; Badman, Samuel; Hellinger, Petr; Bale, Stuart D.

    2018-02-01

    Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfvén wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfvén waves.

  11. Vortex, ULF wave and Aurora Observation after Solar Wind Dynamic Pressure Change

    Science.gov (United States)

    Shi, Q.

    2017-12-01

    Here we will summarize our recent study and show some new results on the Magnetosphere and Ionosphere Response to Dynamic Pressure Change/disturbances in the Solar Wind and foreshock regions. We study the step function type solar wind dynamic pressure change (increase/decrease) interaction with the magnetosphere using THEMIS satellites at both dayside and nightside in different geocentric distances. Vortices generated by the dynamic pressure change passing along the magnetopause are found and compared with model predictions. ULF waves and vortices are excited in the dayside and nightside plasma sheet when dynamic pressure change hit the magnetotail. The related ionospheric responses, such as aurora and TCVs, are also investigated. We compare Global MHD simulations with the observations. We will also show some new results that dayside magnetospheric FLRs might be caused by foreshock structures.Shi, Q. Q. et al. (2013), THEMIS observations of ULF wave excitation in the nightside plasma sheet during sudden impulse events, J. Geophys. Res. Space Physics, 118, doi:10.1029/2012JA017984. Shi, Q. Q. et al. (2014), Solar wind pressure pulse-driven magnetospheric vortices and their global consequences, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019551. Tian, A.M. et al.(2016), Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations, J. Geophys. Res., 121, doi:10.1002/2016JA022459. Shen, X.C. et al.(2015), Magnetospheric ULF waves with increasing amplitude related to solar wind dynamic pressure changes: THEMIS observations, J. Geophys. Res., 120, doi:10.1002/2014JA020913Zhao, H. Y. et al. (2016), Magnetospheric vortices and their global effect after a solar wind dynamic pressure decrease, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA021646. Shen, X. C., et al. (2017), Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse, J. Geophys. Res

  12. Ion acoustic waves and related plasma observations in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

    1979-01-01

    This paper presents an investigation of solar wind ion acoustic waves and their relationship to the macroscopic and microscopic characteristics of the solar wind plasma. Comparisons with the overall solar wind corotational structure show that the most intense ion acoustic waves usually occur in the low-velocity regions ahead of high-speed solar wind streams. Of the detailed plasma parameters investigated, the ion acoustic wave intensities are found to be most closely correlated with the electron to proton temperature ratio T/sub e//T/sub p/ and with the electron heat flux. Investigations of the detailed electron and proton distribution functions also show that the ion acoustic waves usually occur in regions with highly non-Maxwellian distributions characteristic of double-proton streams. The distribution functions for the double-proton streams are usually not resolved into two clearly defined peaks, but rather they appear as a broad shoulder on the main proton distribution. Two main mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. Both mechanisms have favorable and unfavorable features. The electron heat flux mechanism can account for the observed waves at moderate to large ratios of T/sub e//T/sub p/ but has problems when T/sub e//T/sub p/ is small, as sometimes occurs. The ion beam instability appears to provide more flexibility on the T/sub e//T/sub p/ ratio; however detailed comparisons using observed distribution functions indicate that the ion beam mode is usually stable. Possible resolutions of these difficulties are discussed

  13. Wave propagation in a non-isothermal atmosphere and the solar five-minute oscillations. [Acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Chiuderi, C; Giovanardi, C [Florence Univ. (Italy). Istituto di Astronomia

    1979-11-01

    This paper presents a detailed discussion of the properties of linear, periodic acoustic waves that propagate vertically in a non-isothermal atmosphere. In order to retain the basic feature of the solar atmosphere we have chosen a temperature profile presenting a minimum. An analytical solution of the problem is possible if T/..mu.., ..mu.. being the mean molecular weight, varies parabolically with height. The purpose of this study is to point out the qualitative differences existing between the case treated here and the customary analysis based on a locally isothermal treatment. The computed velocity amplitude and the temperature-perturbation as functions of the wave period exhibit a sharp peak in the region between 180 and 300 s, thus showing the possibility of interpreting the five-minute oscillations as a resonant phenomenon. The propagating or stationary nature of the waves is investigated by a study of the phase of the proposed analytical solution.

  14. Turbulence and wave particle interactions in solar-terrestrial plasmas. Annual Status Report, 1 July 1983-30 June 1984

    International Nuclear Information System (INIS)

    Dulk, G.A.; Goldman, M.V.; Toomre, J.

    1985-01-01

    Activities in the following study areas are reported: (1) particle and wave processes in solar flares; (2) solar convection zone turbulence; and (3) solar radiation emission. To investigate the amplification of cyclotron maser radiation in solar flares, a radio frequency. (RF) heating model was developed for the corona surrounding the energy release site. Then nonlinear simulations of compressible convection display prominent penetration by plumes into regions of stable stratification at the base of the solar convection zone, leading to the excitation of internal gravity waves there. Lastly, linear saturation of electron-beam-driven Langmuir waves by ambient density fluctuations, nonlinear saturation by strong turbulence processes, and radiation emission mechanisms are examined. An additional section discusses solar magnetic fields and hydromagnetic waves in inhomogeneous media, and the effect of magnetic fields on stellar oscillation

  15. Short- and Medium-term Atmospheric Effects of Very Large Solar Proton Events

    Science.gov (United States)

    Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Fleming, Eric L.; Labow, Gordon J.; Randall, Cora E.; Lopez-Puertas, Manuel; Funke, Bernd

    2007-01-01

    Long-term variations in ozone have been caused by both natural and humankind related processes. In particular, the humankind or anthropogenic influence on ozone from chlorofluorocarbons and halons (chlorine and bromine) has led to international regulations greatly limiting the release of these substances. These anthropogenic effects on ozone are most important in polar regions and have been significant since the 1970s. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the short- and medium-term (days to a few months) influences of solar proton events between 1963 and 2005 on stratospheric ozone. The four largest events in the past 45 years (August 1972; October 1989; July 2000; and October-November 2003) caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen- containing compounds, which led to the polar ozone destruction. The hydrogen-containing compounds have very short lifetimes and lasted for only a few days (typically the duration of the solar proton event). On the other hand, the nitrogen-containing compounds lasted much longer, especially in the Winter. The nitrogen oxides were predicted

  16. Short-crested waves in deep water: a numerical investigation of recent laboratory experiments

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Madsen, Per A.

    2006-01-01

    A numerical study of quasi-steady, doubly-periodic monochromatic short-crested wave patterns in deep water is conducted using a high-order Boussinesq-type model. Simulations using linear wavemaker conditions in the nonlinear model are initially used to approximate conditions from recent laboratory...... experiments. The computed patterns share many features with those observed in wavetanks, including bending (both frontwards and backwards) of the wave crests, dipping at the crest centerlines, and a pronounced long modulation in the direction of propagation. A new and simple explanation for these features...

  17. Foreshock Langmuir Waves for Unusually Constant Solar Wind Conditions: Data and Implications for Foreshock Structure

    Science.gov (United States)

    Cairns, Iver H.; Robinson, P. A.; Anderson, Roger R.; Strangeway, R. J.

    1997-01-01

    Plasma wave data are compared with ISEE 1's position in the electron foreshock for an interval with unusually constant (but otherwise typical) solar wind magnetic field and plasma characteristics. For this period, temporal variations in the wave characteristics can be confidently separated from sweeping of the spatially varying foreshock back and forth across the spacecraft. The spacecraft's location, particularly the coordinate D(sub f) downstream from the foreshock boundary (often termed DIFF), is calculated by using three shock models and the observed solar wind magnetometer and plasma data. Scatterplots of the wave field versus D(sub f) are used to constrain viable shock models, to investigate the observed scatter in the wave fields at constant D(sub f), and to test the theoretical predictions of linear instability theory. The scatterplots confirm the abrupt onset of the foreshock waves near the upstream boundary, the narrow width in D(sub f) of the region with high fields, and the relatively slow falloff of the fields at large D(sub f), as seen in earlier studies, but with much smaller statistical scatter. The plots also show an offset of the high-field region from the foreshock boundary. It is shown that an adaptive, time-varying shock model with no free parameters, determined by the observed solar wind data and published shock crossings, is viable but that two alternative models are not. Foreshock wave studies can therefore remotely constrain the bow shock's location. The observed scatter in wave field at constant D(sub f) is shown to be real and to correspond to real temporal variations, not to unresolved changes in D(sub f). By comparing the wave data with a linear instability theory based on a published model for the electron beam it is found that the theory can account qualitatively and semiquantitatively for the abrupt onset of the waves near D(sub f) = 0, for the narrow width and offset of the high-field region, and for the decrease in wave intensity

  18. Determining magnetospheric ULF wave activity from external drivers using the most influential solar wind parameters

    Science.gov (United States)

    Bentley, S.; Watt, C.; Owens, M. J.

    2017-12-01

    Ultra-low frequency (ULF) waves in the magnetosphere are involved in the energisation and transport of radiation belt particles and are predominantly driven by the external solar wind. By systematically examining the instantaneous relative contribution of non-derived solar wind parameters and accounting for their interdependencies using fifteen years of ground-based measurements (CANOPUS) at a single frequency and magnetic latitude, we conclude that the dominant causal parameters for ground-based ULF wave power are solar wind speed v, interplanetary magnetic field component Bz and summed power in number density perturbations δNp. We suggest that these correspond to driving by the Kelvin-Helmholtz instability, flux transfer events and direct perturbations from solar wind structures sweeping past. We will also extend our analysis to a stochastic wave model at multiple magnetic latitudes that will be used in future to predict background ULF wave power across the radiation belts in different magnetic local time sectors, and to examine the relative contribution of the parameters v, Bz and var(Np) in these sectors.

  19. Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ofman, Leon, E-mail: Leon.Ofman@nasa.gov [Department of Physics, The Catholic University of America, Washington, DC (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States); Visiting, Department of Geosciences, Tel Aviv University, Tel Aviv (Israel); Ozak, Nataly [Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2016-03-25

    Near the Sun (< 10R{sub s}) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

  20. Validity of the Taylor hypothesis for linear kinetic waves in the weakly collisional solar wind

    International Nuclear Information System (INIS)

    Howes, G. G.; Klein, K. G.; TenBarge, J. M.

    2014-01-01

    The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis—that temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame—is often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such as Solar Probe Plus, threaten to violate the Taylor hypothesis, either due to slow flow of the plasma with respect to the spacecraft or to the dispersive nature of the plasma fluctuations at small scales. Assuming that the frequency of the turbulent fluctuations is characterized by the frequency of the linear waves supported by the plasma, we evaluate the validity of the Taylor hypothesis for the linear kinetic wave modes in the weakly collisional solar wind. The analysis predicts that a dissipation range of solar wind turbulence supported by whistler waves is likely to violate the Taylor hypothesis, while one supported by kinetic Alfvén waves is not.

  1. Alfvén wave heating of heavy ions in the expanding solar wind: Hybrid simulations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Velli, M.; Trávníček, Pavel; Gary, S. P.; Goldstein, B. E.; Liewer, P. C.

    2005-01-01

    Roč. 110, - (2005), A12109/1-A12109/11 ISSN 0148-0227 R&D Projects: GA AV ČR IAA3042403 Institutional research plan: CEZ:AV0Z30420517 Keywords : Alfvén waves * solar wind heating * microinstabilities Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.784, year: 2005

  2. APPARENT CROSS-FIELD SUPERSLOW PROPAGATION OF MAGNETOHYDRODYNAMIC WAVES IN SOLAR PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, T.; Yokoyama, T. [Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Goossens, M.; Doorsselaere, T. Van [Centre for Mathematical Plasma Astrophysics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, Bus 2400, B-3001 Herverlee (Belgium); Soler, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Wright, A. N., E-mail: kaneko@eps.s.u-tokyo.ac.jp [School of Mathematics and Statistics, University of St Andrews, St Andrews, KY16 9SS (United Kingdom)

    2015-10-20

    In this paper we show that the phase-mixing of continuum Alfvén waves and/or continuum slow waves in the magnetic structures of the solar atmosphere as, e.g., coronal arcades, can create the illusion of wave propagation across the magnetic field. This phenomenon could be erroneously interpreted as fast magnetosonic waves. The cross-field propagation due to the phase-mixing of continuum waves is apparent because there is no real propagation of energy across the magnetic surfaces. We investigate the continuous Alfvén and slow spectra in two-dimensional (2D) Cartesian equilibrium models with a purely poloidal magnetic field. We show that apparent superslow propagation across the magnetic surfaces in solar coronal structures is a consequence of the existence of continuum Alfvén waves and continuum slow waves that naturally live on those structures and phase-mix as time evolves. The apparent cross-field phase velocity is related to the spatial variation of the local Alfvén/slow frequency across the magnetic surfaces and is slower than the Alfvén/sound velocities for typical coronal conditions. Understanding the nature of the apparent cross-field propagation is important for the correct analysis of numerical simulations and the correct interpretation of observations.

  3. Silicon is in short supply for the growth in solar cell production

    International Nuclear Information System (INIS)

    Halvorsen, Finn

    2003-01-01

    Polycrystalline silicon will be in short supply by 2006. This is the conclusion of two independent studies, one done for the European Union and one for the Photovoltaic Industry Association. The most important reason is the rapid growth in the solar cell market, which is expected to be about 15 per cent per year until 2010. If so, the world's solar cell manufacturers will need 8,000 tonnes of pure silicon at that time. This growth presupposes that the price of silicon does not rise, but it readily might. Because the general situation for the semiconductor industry has been difficult, silicon has been readily available to the manufacturers of solar cells in recent years. This is true of discard, which has always been used for solar cells, but also of silicon that was intended to become microprocessors, storage chips and other advanced semiconductor devices. As the semiconductor market improves, the amount of silicon from this source will shrink. Manufacturers of solar cells cannot afford to pay as much as the semiconductor manufacturers, and some consider making solar cell grade silicon themselves

  4. Solar Cell Short Circuit Current Errors and Uncertainties During High Altitude Calibrations

    Science.gov (United States)

    Snyder, David D.

    2012-01-01

    High altitude balloon based facilities can make solar cell calibration measurements above 99.5% of the atmosphere to use for adjusting laboratory solar simulators. While close to on-orbit illumination, the small attenuation to the spectra may result in under measurements of solar cell parameters. Variations of stratospheric weather, may produce flight-to-flight measurement variations. To support the NSCAP effort, this work quantifies some of the effects on solar cell short circuit current (Isc) measurements on triple junction sub-cells. This work looks at several types of high altitude methods, direct high altitude meas urements near 120 kft, and lower stratospheric Langley plots from aircraft. It also looks at Langley extrapolation from altitudes above most of the ozone, for potential small balloon payloads. A convolution of the sub-cell spectral response with the standard solar spectrum modified by several absorption processes is used to determine the relative change from AMO, lscllsc(AMO). Rayleigh scattering, molecular scatterin g from uniformly mixed gases, Ozone, and water vapor, are included in this analysis. A range of atmosph eric pressures are examined, from 0. 05 to 0.25 Atm to cover the range of atmospheric altitudes where solar cell calibrations a reperformed. Generally these errors and uncertainties are less than 0.2%

  5. Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis

    Science.gov (United States)

    Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M.

    2016-01-01

    Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.

  6. Wave Heating of the Solar Chromosphere Wolfgang Kalkofen

    Indian Academy of Sciences (India)

    Abstract. The nonmagnetic interior of supergranulation cells has been thought since the 1940s to be heated by the dissipation of acoustic waves. But all attempts to measure the acoustic flux have failed to show suffi- cient energy for chromospheric heating. Recent space observations with. TRACE, for example, have found ...

  7. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= $T_{p, perp}/T_{p, parallel}{-}1$ became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the

  8. Magnetosheath waves under very low solar wind dynamic pressure: Wind/Geotail observations

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2005-06-01

    Full Text Available The expanded bow shock on and around "the day the solar wind almost disappeared" (11 May 1999 allowed the Geotail spacecraft to make a practically uninterrupted 54-h-long magnetosheath pass near dusk (16:30-21:11 magnetic local time at a radial distance of 24 to 30 RE (Earth radii. During most of this period, interplanetary parameters varied gradually and in such a way as to give rise to two extreme magnetosheath structures, one dominated by magnetohydrodynamic (MHD effects and the other by gas dynamic effects. We focus attention on unusual features of electromagnetic ion wave activity in the former magnetosheath state, and compare these features with those in the latter. Magnetic fluctuations in the gas dynamic magnetosheath were dominated by compressional mirror mode waves, and left- and right-hand polarized electromagnetic ion cyclotron (EIC waves transverse to the background field. In contrast, the MHD magnetosheath, lasting for over one day, was devoid of mirror oscillations and permeated instead by EIC waves of weak intensity. The weak wave intensity is related to the prevailing low solar wind dynamic pressures. Left-hand polarized EIC waves were replaced by bursts of right-hand polarized waves, which remained for many hours the only ion wave activity present. This activity occurred when the magnetosheath proton temperature anisotropy (= became negative. This was because the weakened bow shock exposed the magnetosheath directly to the (negative temperature anisotropy of the solar wind. Unlike the normal case studied in the literature, these right-hand waves were not by-products of left-hand polarized waves but derived their energy source directly from the magnetosheath temperature anisotropy. Brief entries into the low latitude boundary layer (LLBL and duskside magnetosphere occurred under such inflated conditions that the magnetospheric magnetic pressure was insufficient to maintain pressure balance. In these crossings, the inner edge of

  9. Evidence for Alfvén Waves in Source Flares of Impulsive Solar Energetic Particle Events

    Science.gov (United States)

    Bucik, R.; Innes, D.; Mason, G. M.; Wiedenbeck, M. E.; Gomez-Herrero, R.; Nitta, N.

    2017-12-01

    Impulsive solar energetic particle events, characterised by a peculiar elemental composition with the rare elements like 3He and ultra-heavy ions enhanced by factors up to ten thousand above their thermal abundance, have been puzzling for almost 50 years. The solar sources of these events have been commonly associated with coronal jets, believed to be a signature of magnetic reconnection involving field lines open to interplanetary space. Here we present some of the most intense events, highly enriched in both 3He and heavier ions. The corresponding high-resolution, extreme-ultraviolet imaging observations have revealed for the first time a helical structure in the source flare with a jet-like shape. A mini-filament at the base of the jet appears to trigger these events. The events were observed with the two Solar Terrestrial Relations Observatories on the backside of the Sun, during the period of increased solar activity in 2014. During the last decade, it has been established that the helical motions in coronal jets represent propagating Alfvén waves. Revealing such magnetic-untwisting waves in the solar sources of highly enriched events in this study is consistent with a stochastic acceleration mechanism. An examination of jets in previously reported impulsive solar energetic particle events indicates that they tend to be large-scale blowout jets, sometimes cleanly showing a twisted configuration.The work of R. Bucik is supported by the Deutsche Forschungsgemeinschaft grant BU 3115/2-1.

  10. Helioseismic measurements in the solar envelope using group velocities of surface waves

    Science.gov (United States)

    Vorontsov, S. V.; Baturin, V. A.; Ayukov, S. V.; Gryaznov, V. K.

    2014-07-01

    At intermediate- and high-degree l, solar p and f modes can be considered as surface waves. Using variational principle, we derive an integral expression for the group velocities of the surface waves in terms of adiabatic eigenfunctions of normal modes, and address the benefits of using group-velocity measurements as a supplementary diagnostic tool in solar seismology. The principal advantage of using group velocities, when compared with direct analysis of the oscillation frequencies, comes from their smaller sensitivity to the uncertainties in the near-photospheric layers. We address some numerical examples where group velocities are used to reveal inconsistencies between the solar models and the seismic data. Further, we implement the group-velocity measurements to the calibration of the specific entropy, helium abundance Y, and heavy-element abundance Z in the adiabatically stratified part of the solar convective envelope, using different recent versions of the equation of state. The results are in close agreement with our earlier measurements based on more sophisticated analysis of the solar oscillation frequencies. These results bring further support to the downward revision of the solar heavy-element abundances in recent spectroscopic measurements.

  11. EXPERIMENTAL DETERMINATION OF WHISTLER WAVE DISPERSION RELATION IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Stansby, D.; Horbury, T. S.; Chen, C. H. K.; Matteini, L., E-mail: david.stansby14@imperial.ac.uk [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-09-20

    The origins and properties of large-amplitude whistler wavepackets in the solar wind are still unclear. In this Letter, we utilize single spacecraft electric and magnetic field waveform measurements from the ARTEMIS mission to calculate the plasma frame frequency and wavevector of individual wavepackets over multiple intervals. This allows direct comparison of experimental measurements with theoretical dispersion relations to identify the observed waves as whistler waves. The whistlers are right-hand circularly polarized, travel anti-sunward, and are aligned with the background magnetic field. Their dispersion is strongly affected by the local electron parallel beta in agreement with linear theory. The properties measured are consistent with the electron heat flux instability acting in the solar wind to generate these waves.

  12. Allowable propagation of short pulse laser beam in a plasma channel and electromagnetic solitary waves

    International Nuclear Information System (INIS)

    Zhang, Shan; Hong, Xue-Ren; Wang, Hong-Yu; Xie, Bai-Song

    2011-01-01

    Nonparaxial and nonlinear propagation of a short intense laser beam in a parabolic plasma channel is analyzed by means of the variational method and nonlinear dynamics. The beam propagation properties are classified by five kinds of behaviors. In particularly, the electromagnetic solitary wave for finite pulse laser is found beside the other four propagation cases including beam periodically oscillating with defocussing and focusing amplitude, constant spot size, beam catastrophic focusing. It is also found that the laser pulse can be allowed to propagate in the plasma channel only when a certain relation for laser parameters and plasma channel parameters is satisfied. For the solitary wave, it may provide an effective way to obtain ultra-short laser pulse.

  13. A Study of Solar Flare Effects on Mid and High Latitude Radio Wave Propagation using SuperDARN.

    Science.gov (United States)

    Ruohoniemi, J. M.; Chakraborty, S.; Baker, J. B.

    2017-12-01

    Over the Horizon (OTH) communication is strongly dependent on the state of the ionosphere, which is sensitive to solar X-ray flares. The Super Dual Auroral Radar Network (SuperDARN), whose working principle is dependent on trans-ionospheric radio communication, uses HF radio waves to remotely sense the ionosphere. The backscatter returns from the terrestrial surface (also known as ground-scatter) transit the ionosphere four times and simulate the operation of an HF communications link. SuperDARN backscatter signal properties are altered (strongly attenuated and changes apparent phase) during a sudden ionospheric disturbance following a solar flare, commonly known as Short-Wave Fadeout or SWF. During an SWF the number of SuperDARN backscatter echoes drops suddenly (≈1 min) and sharply, often to near zero, and recovers within 30 minutes to an hour. In this study HF propagation data (SuperDARN backscatter) obtained during SWF events are analyzed for the purpose of validating and improving the performance of HF absorption models, such as, Space Weather Prediction Center (SWPC) D-region Absorption model (DRAP) and CCMC physics based AbbyNormal model. We will also present preliminary results from a physics based model for the mid and high latitude ionospheric response to flare-driven space weather anomalies, which can be used to estimate different physical parameters of the ionosphere such as electron density, collision frequency, absorption coefficients, response time of D-region etc.

  14. Very Short-term Nonparametric Probabilistic Forecasting of Renewable Energy Generation - with Application to Solar Energy

    DEFF Research Database (Denmark)

    Golestaneh, Faranak; Pinson, Pierre; Gooi, Hoay Beng

    2016-01-01

    Due to the inherent uncertainty involved in renewable energy forecasting, uncertainty quantification is a key input to maintain acceptable levels of reliability and profitability in power system operation. A proposal is formulated and evaluated here for the case of solar power generation, when only...... approach to generate very short-term predictive densities, i.e., for lead times between a few minutes to one hour ahead, with fast frequency updates. We rely on an Extreme Learning Machine (ELM) as a fast regression model, trained in varied ways to obtain both point and quantile forecasts of solar power...... generation. Four probabilistic methods are implemented as benchmarks. Rival approaches are evaluated based on a number of test cases for two solar power generation sites in different climatic regions, allowing us to show that our approach results in generation of skilful and reliable probabilistic forecasts...

  15. A differential optical interferometer for measuring short pulses of surface acoustic waves.

    Science.gov (United States)

    Shaw, Anurupa; Teyssieux, Damien; Laude, Vincent

    2017-09-01

    The measurement of the displacements caused by the propagation of a short pulse of surface acoustic waves on a solid substrate is investigated. A stabilized time-domain differential interferometer is proposed, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped interdigital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200-400MHz frequency range and producing 10-ns pulses with 36nm maximum out-of-plane displacement. The interferometric response is compared with a direct electrical measurement obtained with a receiving wide bandwidth interdigital transducer and good correspondence is observed. The effects of varying the path difference of the interferometer and the measurement position on the surface are discussed. Pulse compression along the chirped interdigital transducer is observed experimentally. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Integrable discretizations for the short-wave model of the Camassa-Holm equation

    International Nuclear Information System (INIS)

    Feng Baofeng; Maruno, Ken-ichi; Ohta, Yasuhiro

    2010-01-01

    The link between the short-wave model of the Camassa-Holm equation (SCHE) and bilinear equations of the two-dimensional Toda lattice equation is clarified. The parametric form of the N-cuspon solution of the SCHE in Casorati determinant is then given. Based on the above finding, integrable semi-discrete and full-discrete analogues of the SCHE are constructed. The determinant solutions of both semi-discrete and fully discrete analogues of the SCHE are also presented.

  17. The collision of multimode dromions and a firewall in the two-component long-wave-short-wave resonance interaction equation

    International Nuclear Information System (INIS)

    Radha, R; Kumar, C Senthil; Lakshmanan, M; Gilson, C R

    2009-01-01

    In this communication, we investigate the two-component long-wave-short-wave resonance interaction equation and show that it admits the Painleve property. We then suitably exploit the recently developed truncated Painleve approach to generate exponentially localized solutions for the short-wave components S (1) and S (2) while the long wave L admits a line soliton only. The exponentially localized solutions driving the short waves S (1) and S (2) in the y-direction are endowed with different energies (intensities) and are called 'multimode dromions'. We also observe that the multimode dromions suffer from intramodal inelastic collision while the existence of a firewall across the modes prevents the switching of energy between the modes. (fast track communication)

  18. Defects influence on short circuit current density in p-i-n silicon solar cell

    International Nuclear Information System (INIS)

    Wagah F Mohamad; Alhan M Mustafa

    2006-01-01

    The admittance analysis method has been used to calculate the collection efficiency and the short circuit current density in a-Si:H p-i-n solar cell, as a function of the thickness of i-layer. Its is evident that the results of the short circuit current can be used to determine the optimal thickness of the i-layer of a cell, and it will be more accurate in comparison with the previous studies using a constant generation rate or an empirical exponential function for the generation of charge carriers throughout the i-layer

  19. Short-lived radioactive nuclides in meteorites and early solar system processes

    International Nuclear Information System (INIS)

    Chaussidon, M.; Gounelle, M.

    2007-01-01

    Now extinct, short-lived radioactive nuclides, such as 7 Be (T 1/2 = 53 days), 10 Be (T 1/2 = 1.5 Ma), 26 Al (T 1/2 = 0.74 Ma), 36 Cl (T 1/2 = 0.3 Ma), 41 Ca (T 1/2 = 0.1 Ma), 53 Mn (T 1/2 = 3.7 Ma) and 60 Fe (T 1/2 = 1.5 Ma), were present in the proto-solar nebula when the various components of meteorites formed. The presence of these radioactive isotopes requires a 'last-minute' origin, either nucleosynthesis in a massive star dying close in space and time to the nascent solar system or production by local irradiation of part of the proto-solar disk by high-energy solar cosmic rays. In this review, we list: (i) the different observations indicating the existence of multiple origins for short-lived radioactive nuclides, namely 7 Be, 10 Be and 36 Cl for irradiation scenario and 60 Fe for injection scenario; (ii) the constraints that exist on their distribution (homogeneous or heterogeneous) in the accretion disk; (iii) the constraints they brought on the timescales of nebular processes (from Ca-Al-rich inclusions to chondrules) and of the accretion and differentiation of planetesimals. (authors)

  20. Influence of wavelength on transient short-circuit current in polycrystalline silicon solar cells

    International Nuclear Information System (INIS)

    Ba, B.; Kane, M.

    1993-10-01

    The influence of the wavelength of a monochromatic illumination on transient short-circuit current in an n/p polycrystalline silicon part solar cell junction is investigated. A wavelength dependence in the initial part of the current decay is observed in the case of cells with moderate grain boundary effects. This influence is attenuated in polycrystalline cells with strong grain boundary activity. (author). 10 refs, 6 figs

  1. Increased short circuit current in an azafullerene-based organic solar cell.

    Science.gov (United States)

    Cambarau, Werther; Fritze, Urs F; Viterisi, Aurélien; Palomares, Emilio; von Delius, Max

    2015-01-21

    We report the synthesis of a solution-processable, dodecyloxyphenyl-substituted azafullerene monoadduct (DPC59N) and its application as electron acceptor in bulk heterojunction organic solar cells (BHJ-OSCs). Due to its relatively strong absorption of visible light, DPC59N outperforms PC60BM in respect to short circuit current (JSC) and external quantum efficiency (EQE) in blends with donor P3HT.

  2. Theoretical Investigation of Peak-Delay Force Reduction for Caissons Exposed to Non-breaking Short-Crested Waves

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Z.

    In nature coastal structures are exposed to oblique short-crested waves. The effect of wave incident angle on total wave force on a long caisson are twofold. The one is the force reduction due to the reduction of instantaneous point pressure on the caisson, named point-pressure force reduction....... The other is the force reduction due to the fact that the peak pressures do not occur simultaneously along the caisson, named peak-delay force reduction. These two reduction effects can also be expected with short-crested waves, as the short-crestedness of waves means the spreading of wave energy over...... a range of incident angles. The peak-delay force reduction, i.e. no simultaneous peak along caisson, is of particular interest because the equipment improvement in construction enables the building of considerably long caissons. In Japan length of caissons exceeds often 100m. This paper will concentrate...

  3. Short Wavelength Electromagnetic Perturbations Excited Near the Solar Probe Plus Spacecraft in the Inner Heliosphere: 2.5D Hybrid Modeling

    Science.gov (United States)

    Lipatov, Alexander S.; Sittler, Edward C.; Hartle, Richard E.; Cooper, John F.

    2011-01-01

    A 2.5D numerical plasma model of the interaction of the solar wind (SW) with the Solar Probe Plus spacecraft (SPPSC) is presented. These results should be interpreted as a basic plasma model derived from the SW-interaction with the spacecraft (SC), which could have consequences for both plasma wave and electron plasma measurements on board the SC in the inner heliosphere. Compression waves and electric field jumps with amplitudes of about 1.5 V/m and (12-18) V/m were also observed. A strong polarization electric field was also observed in the wing of the plasma wake. However, 2.5D hybrid modeling did not show excitation of whistler/Alfven waves in the upstream connected with the bidirectional current closure that was observed in short-time 3D modeling SPPSC and near a tether in the ionosphere. The observed strong electromagnetic perturbations may be a crucial point in the electromagnetic measurements planned for the future Solar Probe Plus (SPP) mission. The results of modeling electromagnetic field perturbations in the SW due to shot noise in absence of SPPSC are also discussed.

  4. Radio wave propagation in the inhomogeneous magnetic field of the solar corona

    International Nuclear Information System (INIS)

    Zheleznyakov, V.V.; Zlotnik, E.Ya.

    1977-01-01

    Various types of linear coupling between ordinary and extra-ordinary waves in the coronal plasma with the inhomogeneous magnetic field and the effect of this phenomenon upon the polarization characteristics of solar radio emission are considered. A qualitative analysis of the wave equation indicates that in a rarefied plasma the coupling effects can be displayed in a sufficiently weak magnetic field or at the angles between the magnetic field and the direction of wave propagation close enough to zero or π/2. The wave coupling parameter are found for these three cases. The radio wave propagation through the region with a quasi-transverse magnetic field and through the neutral current sheet is discussed more in detail. A qualitative picture of coupling in such a layer is supported by a numerical solution of the ''quasi-isotropic approximation'' equations. The role of the coupling effects in formation of polarization characteristics of different components of solar radio emission has been investigated. For cm wave range, the polarization is essentially dependent on the conditions in the region of the transverse magnetic field

  5. 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.

  6. Conversion of piston-driven shocks from powerful solar flares to blast wave shocks in the solar wind

    International Nuclear Information System (INIS)

    Pinter, S.

    1990-01-01

    It was suggested by Smart and Shea (1985) that the time of arrival of solar-flare-generated shock waves at any point in space may be predicted by assuming that they are first driven from the Sun after which they decay into blast shocks. Their study was extended by using the duration of the Type IV radio emission as a phenomenological symptom of the piston-driven phase of these shocks. Using a sample of 39 cases of combined Type II/Type IV observations from 1972 to 1982 solar flares, it was found that the average predicted times-of-arrival of these shocks to Earth (and elsewhere) deviate from the actual times by 1.40 hr with a standard deviation of 1.25 hr. On the average, a representative shock from this sample is emitted from a powerful flare with a velocity of 1,560 km sec -1 ; moves at a constant inertial velocity to a distance of 0.12 AU after which it begins to decelerate as a classical (Sedov-type) blast shock that is convected by the ambient solar wind as suggested by Smart and Shea; and arrives to Earth 45.8 hr after its initiation in the Sun. Shocks that appear to deviate from this phenomenological scenario by virtue of lack of detection on Earth are assumed to decay into fast mode MHD waves. (author). 7 figs., 1 tab., 53 refs

  7. An extreme ultraviolet wave associated with a failed eruption observed by the Solar Dynamics Observatory

    Science.gov (United States)

    Zheng, R.; Jiang, Y.; Yang, J.; Bi, Y.; Hong, J.; Yang, B.; Yang, D.

    2012-05-01

    Aims: Taking advantage of the high temporal and spatial resolution of the Solar Dynamics Observatory (SDO) observations, we present an extreme ultraviolet (EUV) wave associated with a failed filament eruption that generated no coronal mass ejection (CME) on 2011 March 1. We aim at understanding the nature and origin of this EUV wave. Methods: Combining the high-quality observations in the photosphere, the chromosphere, and the corona, we studied the characteristics of the wave and its relations to the associated eruption. Results: The event occurred at an ephemeral region near a small active region. The continuous magnetic flux cancelation in the ephemeral region produced pre-eruption brightenings and two EUV jets, and excited the filament eruption, accompanying it with a microflare. After the eruption, the filament material appeared far from the eruption center, and the ambient loops seemed to be intact. It was evident that the filament eruption had failed and was not associated with a CME. The wave happened just after the north jet arrived, and apparently emanated ahead of the north jet, far from the eruption center. The wave propagated at nearly constant velocities in the range of 260-350 km s-1, with a slight negative acceleration in the last phase. Remarkably, the wave continued to propagate, and a loop in its passage was intact when wave and loop met. Conclusions: Our analysis confirms that the EUV wave is a true wave, which we interpret as a fast-mode wave. In addition, the close temporal and spatial relationship between the wave and the jet provides evidence that the wave was likely triggered by the jet when the CME failed to happen. Three movies are available in electronic form at http://www.aanda.org

  8. Chapter 4: Pulsating Wave Loads Section 4.3: 3D Effects Force Reduction of Short-Crested Non-Breaking Waves on Caissons

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Liu, Zhou

    1999-01-01

    The effect of wave short-crestedness on the horizontal wave force on a caisson is twofold. The one is the force reduction due to the reduction of point pressure on the caisson, named point-pressure reduction. The other is the force reduction due to the fact that the peak pressures do not occur si...

  9. Short-time regularity assessment of fibrillatory waves from the surface ECG in atrial fibrillation

    International Nuclear Information System (INIS)

    Alcaraz, Raúl; Martínez, Arturo; Hornero, Fernando; Rieta, José J

    2012-01-01

    This paper proposes the first non-invasive method for direct and short-time regularity quantification of atrial fibrillatory (f) waves from the surface ECG in atrial fibrillation (AF). Regularity is estimated by computing individual morphological variations among f waves, which are delineated and extracted from the atrial activity (AA) signal, making use of an adaptive signed correlation index. The algorithm was tested on real AF surface recordings in order to discriminate atrial signals with different organization degrees, providing a notably higher global accuracy (90.3%) than the two non-invasive AF organization estimates defined to date: the dominant atrial frequency (70.5%) and sample entropy (76.1%). Furthermore, due to its ability to assess AA regularity wave to wave, the proposed method is also able to pursue AF organization time course more precisely than the aforementioned indices. As a consequence, this work opens a new perspective in the non-invasive analysis of AF, such as the individualized study of each f wave, that could improve the understanding of AF mechanisms and become useful for its clinical treatment. (paper)

  10. Testing gravitational parity violation with coincident gravitational waves and short gamma-ray bursts

    International Nuclear Information System (INIS)

    Yunes, Nicolas; O'Shaughnessy, Richard; Owen, Benjamin J.; Alexander, Stephon

    2010-01-01

    Gravitational parity violation is a possibility motivated by particle physics, string theory, and loop quantum gravity. One effect of it is amplitude birefringence of gravitational waves, whereby left and right circularly polarized waves propagate at the same speed but with different amplitude evolution. Here we propose a test of this effect through coincident observations of gravitational waves and short gamma-ray bursts from binary mergers involving neutron stars. Such gravitational waves are highly left or right circularly polarized due to the geometry of the merger. Using localization information from the gamma-ray burst, ground-based gravitational wave detectors can measure the distance to the source with reasonable accuracy. An electromagnetic determination of the redshift from an afterglow or host galaxy yields an independent measure of this distance. Gravitational parity violation would manifest itself as a discrepancy between these two distance measurements. We exemplify such a test by considering one specific effective theory that leads to such gravitational parity violation, Chern-Simons gravity. We show that the advanced LIGO-Virgo network and all-sky gamma-ray telescopes can be sensitive to the propagating sector of Chern-Simons gravitational parity violation to a level roughly 2 orders of magnitude better than current stationary constraints from the LAGEOS satellites.

  11. ASSOCIATION OF {sup 3}He-RICH SOLAR ENERGETIC PARTICLES WITH LARGE-SCALE CORONAL WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Bučík, Radoslav [Institut für Astrophysik, Georg-August-Universität Göttingen, D-37077, Göttingen (Germany); Innes, Davina E. [Max-Planck-Institut für Sonnensystemforschung, D-37077, Göttingen (Germany); Mason, Glenn M. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Wiedenbeck, Mark E., E-mail: bucik@mps.mpg.de [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2016-12-10

    Small, {sup 3}He-rich solar energetic particle (SEP) events have been commonly associated with extreme-ultraviolet (EUV) jets and narrow coronal mass ejections (CMEs) that are believed to be the signatures of magnetic reconnection, involving field lines open to interplanetary space. The elemental and isotopic fractionation in these events are thought to be caused by processes confined to the flare sites. In this study, we identify 32 {sup 3}He-rich SEP events observed by the Advanced Composition Explorer , near the Earth, during the solar minimum period 2007–2010, and we examine their solar sources with the high resolution Solar Terrestrial Relations Observatory ( STEREO ) EUV images. Leading the Earth, STEREO -A has provided, for the first time, a direct view on {sup 3}He-rich flares, which are generally located on the Sun’s western hemisphere. Surprisingly, we find that about half of the {sup 3}He-rich SEP events in this survey are associated with large-scale EUV coronal waves. An examination of the wave front propagation, the source-flare distribution, and the coronal magnetic field connections suggests that the EUV waves may affect the injection of {sup 3}He-rich SEPs into interplanetary space.

  12. Explicit and exact solutions for a generalized long-short wave resonance equations with strong nonlinear term

    International Nuclear Information System (INIS)

    Shang Yadong

    2005-01-01

    In this paper, the evolution equations with strong nonlinear term describing the resonance interaction between the long wave and the short wave are studied. Firstly, based on the qualitative theory and bifurcation theory of planar dynamical systems, all of the explicit and exact solutions of solitary waves are obtained by qualitative seeking the homoclinic and heteroclinic orbits for a class of Lienard equations. Then the singular travelling wave solutions, periodic travelling wave solutions of triangle functions type are also obtained on the basis of the relationships between the hyperbolic functions and that between the hyperbolic functions with the triangle functions. The varieties of structure of exact solutions of the generalized long-short wave equation with strong nonlinear term are illustrated. The methods presented here also suitable for obtaining exact solutions of nonlinear wave equations in multidimensions

  13. NONLINEAR REFLECTION PROCESS OF LINEARLY POLARIZED, BROADBAND ALFVÉN WAVES IN THE FAST SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Shoda, M.; Yokoyama, T., E-mail: shoda@eps.s.u-tokyo.ac.jp [Department of Earth and Planetary Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2016-04-01

    Using one-dimensional numerical simulations, we study the elementary process of Alfvén wave reflection in a uniform medium, including nonlinear effects. In the linear regime, Alfvén wave reflection is triggered only by the inhomogeneity of the medium, whereas in the nonlinear regime, it can occur via nonlinear wave–wave interactions. Such nonlinear reflection (backscattering) is typified by decay instability. In most studies of decay instabilities, the initial condition has been a circularly polarized Alfvén wave. In this study we consider a linearly polarized Alfvén wave, which drives density fluctuations by its magnetic pressure force. For generality, we also assume a broadband wave with a red-noise spectrum. In the data analysis, we decompose the fluctuations into characteristic variables using local eigenvectors, thus revealing the behaviors of the individual modes. Different from the circular-polarization case, we find that the wave steepening produces a new energy channel from the parent Alfvén wave to the backscattered one. Such nonlinear reflection explains the observed increasing energy ratio of the sunward to the anti-sunward Alfvénic fluctuations in the solar wind with distance against the dynamical alignment effect.

  14. Kelvin wave coupling from TIMED and GOCE: Inter/intra-annual variability and solar activity effects

    Science.gov (United States)

    Gasperini, Federico; Forbes, Jeffrey M.; Doornbos, Eelco N.; Bruinsma, Sean L.

    2018-06-01

    The primary mechanism through which energy and momentum are transferred from the lower atmosphere to the thermosphere is through the generation and propagation of atmospheric waves. It is becoming increasingly evident that a few waves from the tropical wave spectrum preferentially propagate into the thermosphere and contribute to modify satellite drag. Two of the more prominent and well-established tropical waves are Kelvin waves: the eastward-propagating 3-day ultra-fast Kelvin wave (UFKW) and the eastward-propagating diurnal tide with zonal wave number 3 (DE3). In this work, Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperatures at 110 km and Gravity field and steady-state Ocean Circulation Explorer (GOCE) neutral densities and cross-track winds near 260 km are used to demonstrate vertical coupling in this height regime due to the UFKW and DE3. Significant inter- and intra-annual variability is found in DE3 and the UFKW, with evidence of latitudinal broadening and filtering of the latitude structures with height due to the effect of dissipation and mean winds. Additionally, anti-correlation between the vertical penetration of these waves to the middle thermosphere and solar activity level is established and explained through the effect of molecular dissipation.

  15. Heating and Acceleration of Solar Wind Ions by Turbulent Wave Spectrum in Inhomogeneous Expanding Plasma

    Science.gov (United States)

    Ofman, Leon; Ozak, Nataly; Vinas, Adolfo F.

    2016-01-01

    Near the Sun (plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super- Alfvenic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

  16. Nonlinear generation of kinetic-scale waves by magnetohydrodynamic Alfvén waves and nonlocal spectral transport in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J. S.; Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing (China); Voitenko, Y.; De Keyser, J., E-mail: js_zhao@pmo.ac.cn [Solar-Terrestrial Centre of Excellence, Space Physics Division, Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire, B-1180 Brussels (Belgium)

    2014-04-20

    We study the nonlocal nonlinear coupling and generation of kinetic Alfvén waves (KAWs) and kinetic slow waves (KSWs) by magnetohydrodynamic Alfvén waves (MHD AWs) in conditions typical for the solar wind in the inner heliosphere. This cross-scale process provides an alternative to the turbulent energy cascade passing through many intermediate scales. The nonlinearities we study are proportional to the scalar products of wave vectors and hence are called 'scalar' ones. Despite the strong Landau damping of kinetic waves, we found fast growing KAWs and KSWs at perpendicular wavelengths close to the ion gyroradius. Using the parametric decay formalism, we investigate two independent decay channels for the pump AW: forward decay (involving co-propagating product waves) and backward decay (involving counter-propagating product waves). The growth rate of the forward decay is typically 0.05 but can exceed 0.1 of the pump wave frequency. The resulting spectral transport is nonlocal and anisotropic, sharply increasing perpendicular wavenumbers but not parallel ones. AWs and KAWs propagating against the pump AW grow with about the same rate and contribute to the sunward wave flux in the solar wind. Our results suggest that the nonlocal decay of MHD AWs into KAWs and KSWs is a robust mechanism for the cross-scale spectral transport of the wave energy from MHD to dissipative kinetic scales in the solar wind and similar media.

  17. MHD waves detected by ice at distances > 28 x 106 km from Comet Halley: Cometary or solar wind origin

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Brinca, A.L.; Smith, E.J.; Thorne, R.M.; Scarf, F.L.; Gosling, J.T.; Ipavich, F.M.

    1986-01-01

    Spectral analyses of the high resolution magnetic field data are employed to determine if there is evidence of cometary heavy ion pickup when ICE was closest to Halley, ∼28 x 10 6 km. No evidence is found for the presence of heavy ion cyclotron waves. However, from this search, two new wave modes are discovered in the solar wind: electromagnetic ion cyclotron waves and drift mirror mode waves. Both modes have scales of 10 to 60 s (1 to 6 T/sub p/) in the spacecraft frame. The possibility of wave generation by cometary hydrogen pickup is explored. Theoretical arguments and further experimental evidence indicates that cometary origin is improbable. The most likely source is plasma instabilities associated with solar wind stream-stream interactions. VLF electrostatic emissions are found to occur in field minima or at gradients of the drift mirror structures. Possible generation mechanisms of drift mirror mode waves, cyclotron waves and electrostatic waves are discussed

  18. CORONAL JETS SIMULATED WITH THE GLOBAL ALFVÉN WAVE SOLAR MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Szente, J.; Toth, G.; Manchester IV, W. B.; Holst, B. van der; Landi, E.; Gombosi, T. I. [Climate and Space Sciences and Engineering Department, University of Michigan, Ann Arbor, MI 48109 (United States); DeVore, C. R.; Antiochos, S. K., E-mail: judithsz@umich.edu [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2017-01-10

    This paper describes a numerical modeling study of coronal jets to understand their effects on the global corona and their contribution to the solar wind. We implement jets into a well-established three-dimensional, two-temperature magnetohydrodynamic (MHD) solar corona model employing Alfvén-wave dissipation to produce a realistic solar-wind background. The jets are produced by positioning a compact magnetic dipole under the solar surface and rotating the boundary plasma around the dipole's magnetic axis. The moving plasma drags the magnetic field lines along with it, ultimately leading to a reconnection-driven jet similar to that described by Pariat et al. We compare line-of-sight synthetic images to multiple jet observations at EUV and X-ray bands, and find very close matches in terms of physical structure, dynamics, and emission. Key contributors to this agreement are the greatly enhanced plasma density and temperature in our jets compared to previous models. These enhancements arise from the comprehensive thermodynamic model that we use and, also, our inclusion of a dense chromosphere at the base of our jet-generating regions. We further find that the large-scale corona is affected significantly by the outwardly propagating torsional Alfvén waves generated by our polar jet, across 40° in latitude and out to 24 R {sub ⊙}. We estimate that polar jets contribute only a few percent to the steady-state solar-wind energy outflow.

  19. A KINETIC ALFVEN WAVE AND THE PROTON DISTRIBUTION FUNCTION IN THE FAST SOLAR WIND

    International Nuclear Information System (INIS)

    Li Xing; Lu Quanming; Chen Yao; Li Bo; Xia Lidong

    2010-01-01

    Using one-dimensional test particle simulations, the effect of a kinetic Alfven wave on the velocity distribution function (VDF) of protons in the collisionless solar wind is investigated. We first use linear Vlasov theory to numerically obtain the property of a kinetic Alfven wave (the wave propagates in the direction almost perpendicular to the background magnetic field). We then numerically simulate how the wave will shape the proton VDF. It is found that Landau resonance may be able to generate two components in the initially Maxwellian proton VDF: a tenuous beam component along the direction of the background magnetic field and a core component. The streaming speed of the beam relative to the core proton component is about 1.2-1.3 Alfven speed.

  20. HEATING AND ACCELERATION OF THE FAST SOLAR WIND BY ALFVÉN WAVE TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Van Ballegooijen, A. A.; Asgari-Targhi, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-04-20

    We present numerical simulations of reduced magnetohydrodynamic (RMHD) turbulence in a magnetic flux tube at the center of a polar coronal hole. The model for the background atmosphere is a solution of the momentum equation and includes the effects of wave pressure on the solar wind outflow. Alfvén waves are launched at the coronal base and reflect at various heights owing to variations in Alfvén speed and outflow velocity. The turbulence is driven by nonlinear interactions between the counterpropagating Alfvén waves. Results are presented for two models of the background atmosphere. In the first model the plasma density and Alfvén speed vary smoothly with height, resulting in minimal wave reflections and low-energy dissipation rates. We find that the dissipation rate is insufficient to maintain the temperature of the background atmosphere. The standard phenomenological formula for the dissipation rate significantly overestimates the rate derived from our RMHD simulations, and a revised formula is proposed. In the second model we introduce additional density variations along the flux tube with a correlation length of 0.04 R {sub ⊙} and with relative amplitude of 10%. These density variations simulate the effects of compressive MHD waves on the Alfvén waves. We find that such variations significantly enhance the wave reflection and thereby the turbulent dissipation rates, producing enough heat to maintain the background atmosphere. We conclude that interactions between Alfvén and compressive waves may play an important role in the turbulent heating of the fast solar wind.

  1. SMALL-SCALE SOLAR WIND TURBULENCE DUE TO NONLINEAR ALFVÉN WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sanjay; Moon, Y.-J. [School of Space Research, Kyung Hee University, Yongin, Gyeonggi-Do, 446-701 (Korea, Republic of); Sharma, R. P., E-mail: sanjaykumar@khu.ac.kr [Centre for Energy Studies, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, 110016 (India)

    2015-10-10

    We present an evolution of wave localization and magnetic power spectra in solar wind plasma using kinetic Alfvén waves (AWs) and fast AWs. We use a two-fluid model to derive the dynamical equations of these wave modes and then numerically solve these nonlinear dynamical equations to analyze the power spectra and wave localization at different times. The ponderomotive force associated with the kinetic AW (or pump) is responsible for the wave localization, and these thin slabs (or sheets) become more chaotic as the system evolves with time until the modulational instability (or oscillating two-stream instability) saturates. From our numerical results, we notice a steepening of the spectra from the inertial range (k{sup −1.67}) to the dispersion range (k{sup −3.0}). The steepening of the spectra could be described as the energy transference from longer to smaller scales. The formation of complex magnetic thin slabs and the change of the spectral index may be considered to be the main reason for the charged particles acceleration in solar wind plasma.

  2. A consistent thermodynamics of the MHD wave-heated two-fluid solar wind

    Directory of Open Access Journals (Sweden)

    I. V. Chashei

    Full Text Available We start our considerations from two more recent findings in heliospheric physics: One is the fact that the primary solar wind protons do not cool off adiabatically with distance, but appear to be heated. The other one is that secondary protons, embedded in the solar wind as pick-up ions, behave quasi-isothermal at their motion to the outer heliosphere. These two phenomena must be physically closely connected with each other. To demonstrate this we solve a coupled set of enthalpy flow conservation equations for the two-fluid solar wind system consisting of primary and secondary protons. The coupling of these equations comes by the heat sources that are relevant, namely the dissipation of MHD turbulence power to the respective protons at the relevant dissipation scales. Hereby we consider both the dissipation of convected turbulences and the dissipation of turbulences locally driven by the injection of new pick-up ions into an unstable mode of the ion distribution function. Conversion of free kinetic energy of freshly injected secondary ions into turbulence power is finally followed by partial reabsorption of this energy both by primary and secondary ions. We show solutions of simultaneous integrations of the coupled set of differential thermodynamic two-fluid equations and can draw interesting conclusions from the solutions obtained. We can show that the secondary proton temperature with increasing radial distance asymptotically attains a constant value with a magnitude essentially determined by the actual solar wind velocity. Furthermore, we study the primary proton temperature within this two-fluid context and find a polytropic behaviour with radially and latitudinally variable polytropic indices determined by the local heat sources due to dissipated turbulent wave energy. Considering latitudinally variable solar wind conditions, as published by McComas et al. (2000, we also predict latitudinal variations of primary proton temperatures at

  3. A consistent thermodynamics of the MHD wave-heated two-fluid solar wind

    Directory of Open Access Journals (Sweden)

    I. V. Chashei

    2003-07-01

    Full Text Available We start our considerations from two more recent findings in heliospheric physics: One is the fact that the primary solar wind protons do not cool off adiabatically with distance, but appear to be heated. The other one is that secondary protons, embedded in the solar wind as pick-up ions, behave quasi-isothermal at their motion to the outer heliosphere. These two phenomena must be physically closely connected with each other. To demonstrate this we solve a coupled set of enthalpy flow conservation equations for the two-fluid solar wind system consisting of primary and secondary protons. The coupling of these equations comes by the heat sources that are relevant, namely the dissipation of MHD turbulence power to the respective protons at the relevant dissipation scales. Hereby we consider both the dissipation of convected turbulences and the dissipation of turbulences locally driven by the injection of new pick-up ions into an unstable mode of the ion distribution function. Conversion of free kinetic energy of freshly injected secondary ions into turbulence power is finally followed by partial reabsorption of this energy both by primary and secondary ions. We show solutions of simultaneous integrations of the coupled set of differential thermodynamic two-fluid equations and can draw interesting conclusions from the solutions obtained. We can show that the secondary proton temperature with increasing radial distance asymptotically attains a constant value with a magnitude essentially determined by the actual solar wind velocity. Furthermore, we study the primary proton temperature within this two-fluid context and find a polytropic behaviour with radially and latitudinally variable polytropic indices determined by the local heat sources due to dissipated turbulent wave energy. Considering latitudinally variable solar wind conditions, as published by McComas et al. (2000, we also predict latitudinal variations of primary proton temperatures at

  4. Sub-grid-scale effects on short-wave instability in magnetized hall-MHD plasma

    International Nuclear Information System (INIS)

    Miura, H.; Nakajima, N.

    2010-11-01

    Aiming to clarify effects of short-wave modes on nonlinear evolution/saturation of the ballooning instability in the Large Helical Device, fully three-dimensional simulations of the single-fluid MHD and the Hall MHD equations are carried out. A moderate parallel heat conductivity plays an important role both in the two kinds of simulations. In the single-fluid MHD simulations, the parallel heat conduction effectively suppresses short-wave ballooning modes but it turns out that the suppression is insufficient in comparison to an experimental result. In the Hall MHD simulations, the parallel heat conduction triggers a rapid growth of the parallel flow and enhance nonlinear couplings. A comparison between single-fluid and the Hall MHD simulations reveals that the Hall MHD model does not necessarily improve the saturated pressure profile, and that we may need a further extension of the model. We also find by a comparison between two Hall MHD simulations with different numerical resolutions that sub-grid-scales of the Hall term should be modeled to mimic an inverse energy transfer in the wave number space. (author)

  5. Rocket photographs of fine structure and wave patterns in the solar temperature minimum

    Science.gov (United States)

    Bonnet, R. M.; Decaudin, M.; Foing, B.; Bruner, M.; Acton, L. W.; Brown, W. A.

    1982-01-01

    A new series of high resolution pictures of the sun has been obtained during the second flight of the Transition Region Camera which occurred on September 23, 1980. The qualitative analysis of the results indicates that a substantial portion of the solar surface at the temperature minimum radiates in non-magnetic regions and from features below 1 arcsec in size. Wave patterns are observed on the 160 nm temperature minimum pictures. They are absent on the Lyman alpha pictures. Their physical characteristics are compatible with those of gravitational and acoustic waves generated by exploding granules.

  6. Solar Terminator Waves in the Ionosphere Measured by the Wallops Island, VA Dynasonde

    Science.gov (United States)

    Zabotin, N. A.; Song, H.; Bullett, T. W.

    2017-12-01

    Solar terminator represents a unique source of atmospheric waves possessing of near-ideal coherent properties: its geometry and magnitude of the impact changes very little from day to day. This feature has been used in [Forbes et al., GRL, 2008] to obtain "snapshots" of terminator waves in the neutral atmosphere at the altitude 400 km by averaging CHAMP accelerometer data over relatively long sequences of the satellite passes. The results were represented in the geographic latitude vs local time coordinates. We apply a similar approach averaging time series of Wallops Island, VA Dynasonde Doppler data to obtain "snapshots" of terminator waves in the ionosphere in the true altitude vs local "terminator time" coordinates. The averaging is performed independently for every month of the yearlong observation period from May 2013 to April 2014. The altitude range covered is 90 km to 400 km with 2 km resolution, representing the entire bottom-side ionosphere. Individual local time segments used for the averaging were 12 hours long and all centered at the times of the sunrise or sunset terminator passing at every specific altitude. This procedure effectively suppresses all kinds of incoherent wave activity and allows one to reveal the perturbation phenomenon mainly caused by the solar terminator. This is an important advantage of this technique compared to multiple "terminator wave" studies based on simple time coincidence. Both sunrise and sunset terminator waves are easily visualized in all of the monthly images. Our results confirm observations of [Forbes et al., GRL, 2008] of the wave structures existing on both sides of the terminator. The phase fronts of the sunset terminator wave are propagating downward indicating upward movement of the terminator-related disturbance and of the wave energy generated by it. The phase fronts of the sunrise terminator waves are propagating upward indicating downward movement of the terminator-related disturbance and of the wave energy

  7. Final report for Fundamental study of long-short interfacial wave interactions with application for flow regime development

    CERN Document Server

    McCready, M

    2000-01-01

    The long waves that cause slugs almost always form more slowly than short waves, and linear stability always predicts that the growth rate for long waves is much less than that for short waves. However, at many conditions above neutral stability, long waves dominate the wave field. Three different studies were undertaken as part of the funded work: (1) linear interaction for unsteady flows; (2) wave evolution in oil-water channel flows; (3) retrograde stability and subcritical bifurcations. The oil-water system was used as a surrogate for gas-liquid systems because the gas phase is usually turbulent, and this complication is thus avoided although the phenomena involved are similar. The following overall conclusions about flow regime development were reached: (a) Oscillations in pressure and flow rate, due to interfacial waves or a malfunctioning pump, can cause significant growth rate changes in short waves within narrow FR-equency ranges, but probably do not have a large effect on long waves and thus regime ...

  8. ON THE SPATIAL SCALES OF WAVE HEATING IN THE SOLAR CHROMOSPHERE

    International Nuclear Information System (INIS)

    Soler, Roberto; Ballester, Jose Luis; Carbonell, Marc

    2015-01-01

    Dissipation of magnetohydrodynamic (MHD) wave energy has been proposed as a viable heating mechanism in the solar chromospheric plasma. Here, we use a simplified one-dimensional model of the chromosphere to theoretically investigate the physical processes and spatial scales that are required for the efficient dissipation of Alfvén waves and slow magnetoacoustic waves. We consider the governing equations for a partially ionized hydrogen-helium plasma in the single-fluid MHD approximation and include realistic wave damping mechanisms that may operate in the chromosphere, namely, Ohmic and ambipolar magnetic diffusion, viscosity, thermal conduction, and radiative losses. We perform an analytic local study in the limit of small amplitudes to approximately derive the lengthscales for critical damping and efficient dissipation of MHD wave energy. We find that the critical dissipation lengthscale for Alfvén waves depends strongly on the magnetic field strength and ranges from 10 m to 1 km for realistic field strengths. The damping of Alfvén waves is dominated by Ohmic diffusion for weak magnetic field and low heights in the chromosphere, and by ambipolar diffusion for strong magnetic field and medium/large heights in the chromosphere. Conversely, the damping of slow magnetoacoustic waves is less efficient, and spatial scales shorter than 10 m are required for critical damping. Thermal conduction and viscosity govern the damping of slow magnetoacoustic waves and play an equally important role at all heights. These results indicate that the spatial scales at which strong wave heating may work in the chromosphere are currently unresolved by observations

  9. ON THE SPATIAL SCALES OF WAVE HEATING IN THE SOLAR CHROMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Ballester, Jose Luis [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain); Carbonell, Marc, E-mail: roberto.soler@uib.es [Institute of Applied Computing and Community Code (IAC), Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2015-09-10

    Dissipation of magnetohydrodynamic (MHD) wave energy has been proposed as a viable heating mechanism in the solar chromospheric plasma. Here, we use a simplified one-dimensional model of the chromosphere to theoretically investigate the physical processes and spatial scales that are required for the efficient dissipation of Alfvén waves and slow magnetoacoustic waves. We consider the governing equations for a partially ionized hydrogen-helium plasma in the single-fluid MHD approximation and include realistic wave damping mechanisms that may operate in the chromosphere, namely, Ohmic and ambipolar magnetic diffusion, viscosity, thermal conduction, and radiative losses. We perform an analytic local study in the limit of small amplitudes to approximately derive the lengthscales for critical damping and efficient dissipation of MHD wave energy. We find that the critical dissipation lengthscale for Alfvén waves depends strongly on the magnetic field strength and ranges from 10 m to 1 km for realistic field strengths. The damping of Alfvén waves is dominated by Ohmic diffusion for weak magnetic field and low heights in the chromosphere, and by ambipolar diffusion for strong magnetic field and medium/large heights in the chromosphere. Conversely, the damping of slow magnetoacoustic waves is less efficient, and spatial scales shorter than 10 m are required for critical damping. Thermal conduction and viscosity govern the damping of slow magnetoacoustic waves and play an equally important role at all heights. These results indicate that the spatial scales at which strong wave heating may work in the chromosphere are currently unresolved by observations.

  10. SHORT-TERM SOLAR FLARE LEVEL PREDICTION USING A BAYESIAN NETWORK APPROACH

    International Nuclear Information System (INIS)

    Yu Daren; Huang Xin; Hu Qinghua; Zhou Rui; Wang Huaning; Cui Yanmei

    2010-01-01

    A Bayesian network approach for short-term solar flare level prediction has been proposed based on three sequences of photospheric magnetic field parameters extracted from Solar and Heliospheric Observatory/Michelson Doppler Imager longitudinal magnetograms. The magnetic measures, the maximum horizontal gradient, the length of neutral line, and the number of singular points do not have determinate relationships with solar flares, so the solar flare level prediction is considered as an uncertainty reasoning process modeled by the Bayesian network. The qualitative network structure which describes conditional independent relationships among magnetic field parameters and the quantitative conditional probability tables which determine the probabilistic values for each variable are learned from the data set. Seven sequential features-the maximum, the mean, the root mean square, the standard deviation, the shape factor, the crest factor, and the pulse factor-are extracted to reduce the dimensions of the raw sequences. Two Bayesian network models are built using raw sequential data (BN R ) and feature extracted data (BN F ), respectively. The explanations of these models are consistent with physical analyses of experts. The performances of the BN R and the BN F appear comparable with other methods. More importantly, the comprehensibility of the Bayesian network models is better than other methods.

  11. Numerical simulation of lowest-order short-crested wave instabilities

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Madsen, Per A.; Bingham, Harry

    2006-01-01

    instabilities. These correctly lead to well-known (nearly symmetric) recurrence cycles below a previously established breaking threshold steepness, and to an asymmetric evolution (characterized by a permanent transfer of energy to the lower side-band) above this threshold, with dissipation from a smoothing...... that the unstable evolution of these initially three-dimensional waves leads to an asymmetric evolution, even for weakly nonlinear cases presumably well below breaking. This is characterized by an energy transfer to the lower side-band, which is also accompanied by a similar transfer to more distant upper side......-bands. At larger steepness, the evolution leads to a permanent downshift of both the mean and peak frequencies, driven in part by dissipation, effectively breaking the quasi-recurrence cycle. A single case involving a class Ib short-crested wave instability at relatively large steepness is also considered, which...

  12. Whistler mode waves and the electron heat flux in the solar wind: Cluster observations

    Czech Academy of Sciences Publication Activity Database

    Lacombe, C.; Alexandrova, O.; Matteini, L.; Santolík, Ondřej; Cornilleau-Wehrlin, N.; Mangeney, A.; De Conchy, Y.; Maksimovic, M.

    2014-01-01

    Roč. 796, č. 1 (2014), s. 1-11 ISSN 0004-637X R&D Projects: GA ČR GAP205/10/2279; GA MŠk LH12231 Institutional support: RVO:68378289 Keywords : solar wind * turbulence * waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 5.993, year: 2014 http://iopscience.iop.org/0004-637X/796/1/5/article

  13. Waves and Turbulence in the Solar Corona: A Surplus of Sources and Sinks

    Science.gov (United States)

    Cranmer, Steven R.

    2018-06-01

    The Sun's corona is a hot, dynamic, and highly stochastic plasma environment, and we still do not yet understand how it is heated. Both the loop-filled coronal base and the extended acceleration region of the solar wind appear to be filled with waves and turbulent eddies. Models that invoke the dissipation of these magnetohydrodynamic (MHD) fluctuations have had some success in explaining the heating. In this presentation I will review some new insights about the different ways these waves are thought to be created and destroyed. For example: (1) Intergranular bright points in the photosphere are believed to extend upwards as coronal flux tubes, and their transverse oscillations are driven by the underlying convection. New high-resolution MHD simulations predict the kinetic energy spectra of the resulting coronal waves and serve as predictions for upcoming DKIST observations. (2) Magnetic reconnection in the supergranular network of the low corona can also generate MHD waves, and new Monte Carlo models of the resulting power spectra will be presented. The total integrated power in these waves is typically small in comparison to that of photosphere-driven waves, but they dominate the total spectrum at periods longer than about 30 minutes. (3) Because each magnetic field line in the corona is tied to at least one specific chromospheric footpoint (each with its own base pressure), the corona also plays host to field-aligned "density striations." These fluctuations vary with the supergranular network on timescales of roughly a day, but they also act as a spatially varying background through which the higher-frequency waves propagate. These multiple sources of space/time variability must be taken into account to properly understand off-limb measurements from CoMP and EIS/Hinode, as well as in-situ measurements from Parker Solar Probe.

  14. On the short circuit resilience of organic solar cells: prediction and validation.

    Science.gov (United States)

    Oostra, A Jolt; Smits, Edsger C P; de Leeuw, Dago M; Blom, Paul W M; Michels, Jasper J

    2015-09-07

    The operational characteristics of organic solar cells manufactured with large area processing methods suffers from the occurrence of short-circuits due to defects in the photoactive thin film stack. In this work we study the effect of a shunt resistance on an organic solar cell and demonstrate that device performance is not affected negatively as long as the shunt resistance is higher than approximately 1000 Ohm. By studying charge transport across PSS-lithium fluoride/aluminum (LiF/Al) shunting junctions we show that this prerequisite is already met by applying a sufficiently thick (>1.5 nm) LiF layer. We demonstrate that this remarkable shunt-resilience stems from the formation of a significant charge transport barrier at the PSS-LiF/Al interface. We validate our predictions by fabricating devices with deliberately severed photoactive layers and find an excellent agreement between the calculated and experimental current-voltage characteristics.

  15. Association of 3He-rich solar energetic particles with large-scale coronal waves

    Science.gov (United States)

    Bucik, Radoslav; Innes, Davina; Guo, Lijia; Mason, Glenn M.; Wiedenbeck, Mark

    2016-07-01

    Impulsive or 3He-rich solar energetic particle (SEP) events have been typically associated with jets or small EUV brightenings. We identify 30 impulsive SEP events from ACE at L1 during the solar minimum period 2007-2010 and examine their solar sources with high resolution STEREO-A EUV images. At beginning of 2007, STEREO-A was near the Earth while at the end of the investigated period, when there were more events, STEREO-A was leading the Earth by 90°. Thus STEREO-A provided a better (more direct) view on 3He-rich flares generally located on the western Sun's hemisphere. Surprisingly, we find that about half of the events are associated with large-scale EUV coronal waves. This finding provides new insights on acceleration and transport of 3He-rich SEPs in solar corona. It is believed that elemental and isotopic fractionation in impulsive SEP events is caused by more localized processes operating in the flare sites. The EUV waves have been reported in gradual SEP events in association with fast coronal mass ejections. To examine their role on 3He-rich SEPs production the energy spectra and relative abundances are discussed. R. Bucik is supported by the Deutsche Forschungsgemeinschaft under grant BU 3115/2-1.

  16. QUASI-BIENNIAL OSCILLATIONS IN THE SOLAR TACHOCLINE CAUSED BY MAGNETIC ROSSBY WAVE INSTABILITIES

    International Nuclear Information System (INIS)

    Zaqarashvili, Teimuraz V.; Carbonell, Marc; Oliver, Ramon; Ballester, Jose Luis

    2010-01-01

    Quasi-biennial oscillations (QBOs) are frequently observed in solar activity indices. However, no clear physical mechanism for the observed variations has been suggested so far. Here, we study the stability of magnetic Rossby waves in the solar tachocline using the shallow water magnetohydrodynamic approximation. Our analysis shows that the combination of typical differential rotation and a toroidal magnetic field with a strength of ≥10 5 G triggers the instability of the m = 1 magnetic Rossby wave harmonic with a period of ∼2 years. This harmonic is antisymmetric with respect to the equator and its period (and growth rate) depends on the differential rotation parameters and magnetic field strength. The oscillations may cause a periodic magnetic flux emergence at the solar surface and consequently may lead to the observed QBO in solar activity features. The period of QBOs may change throughout a cycle, and from cycle to cycle, due to variations of the mean magnetic field and differential rotation in the tachocline.

  17. Hadronic wave functions at short distances and the operator product expansion

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Lepage, G.P.

    1980-01-01

    The operator product expansion, of appropriate products of quark fields, is used to find the anamalous dimensions which control the short distance behavior of hadronic wave functions. This vehavior in turn controls the high-Q 2 limit of hadronic form factors. In particular, we relate each anamalous dimension of the nonsinglet structure functions to a corresponding logarithmic correction factor to the nominal αsub(s)(Q 2 )/Q 2 fall off of meson form factors. Unlike the case of deep inelastic lepton-hadron scattering, the operator product necessary here involves extra terms which do not contribute to forward matrix elements. (orig.)

  18. STATISTICAL ANALYSIS OF ACOUSTIC WAVE PARAMETERS NEAR SOLAR ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-01-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  19. The effect of different solar simulators on the measurement of short-circuit current temperature coefficients

    Science.gov (United States)

    Curtis, H. B.; Hart, R. E., Jr.

    1982-01-01

    Gallium arsenide solar cells are considered for several high temperature missions in space. Both near-Sun and concentrator missions could involve cell temperatures on the order of 200 C. Performance measurements of cells at elevated temperatures are usually made using simulated sunlight and a matched reference cell. Due to the change in bandgap with increasing temperature at portions of the spectrum where considerable simulated irradiance is present, there are significant differences in measured short circuit current at elevated temperatures among different simulators. To illustrate this, both experimental and theoretical data are presented for gallium arsenide cells.

  20. Acoustic waves in the solar atmosphere. VII - Non-grey, non-LTE H(-) models

    Science.gov (United States)

    Schmitz, F.; Ulmschneider, P.; Kalkofen, W.

    1985-01-01

    The propagation and shock formation of radiatively damped acoustic waves in the solar chromosphere are studied under the assumption that H(-) is the only absorber; the opacity is non-grey. Deviations from local thermodynamic equilibrium (LTE) are permitted. The results of numerical simulations show the depth dependence of the heating by the acoustic waves to be insensitive to the mean state of the atmosphere. After the waves have developed into shocks, their energy flux decays exponentially with a constant damping length of about 1.4 times the pressure scale height, independent of initial flux and wave period. Departures from LTE have a strong influence on the mean temperature structure in dynamical chromosphere models; this is even more pronounced in models with reduced particle density - simulating conditions in magnetic flux tubes - which show significantly increased temperatures in response to mechanical heating. When the energy dissipation of the waves is sufficiently large to dissociate most of the H(-) ions, a strong temperature rise is found that is reminiscent of the temperature structure in the transition zone between chromosphere and corona; the energy flux remaining in the waves then drives mass motions.

  1. Comparison of Damping Mechanisms for Transverse Waves in Solar Coronal Loops

    Energy Technology Data Exchange (ETDEWEB)

    Montes-Solís, María; Arregui, Iñigo, E-mail: mmsolis@iac.es [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2017-09-10

    We present a method to assess the plausibility of alternative mechanisms to explain the damping of magnetohydrodynamic transverse waves in solar coronal loops. The considered mechanisms are resonant absorption of kink waves in the Alfvén continuum, phase mixing of Alfvén waves, and wave leakage. Our methods make use of Bayesian inference and model comparison techniques. We first infer the values for the physical parameters that control the wave damping, under the assumption of a particular mechanism, for typically observed damping timescales. Then, the computation of marginal likelihoods and Bayes factors enable us to quantify the relative plausibility between the alternative mechanisms. We find that, in general, the evidence is not large enough to support a single particular damping mechanism as the most plausible one. Resonant absorption and wave leakage offer the most probable explanations in strong damping regimes, while phase mixing is the best candidate for weak/moderate damping. When applied to a selection of 89 observed transverse loop oscillations, with their corresponding measurements of damping timescales and taking into account data uncertainties, we find that positive evidence for a given damping mechanism is only available in a few cases.

  2. Comparison of Damping Mechanisms for Transverse Waves in Solar Coronal Loops

    International Nuclear Information System (INIS)

    Montes-Solís, María; Arregui, Iñigo

    2017-01-01

    We present a method to assess the plausibility of alternative mechanisms to explain the damping of magnetohydrodynamic transverse waves in solar coronal loops. The considered mechanisms are resonant absorption of kink waves in the Alfvén continuum, phase mixing of Alfvén waves, and wave leakage. Our methods make use of Bayesian inference and model comparison techniques. We first infer the values for the physical parameters that control the wave damping, under the assumption of a particular mechanism, for typically observed damping timescales. Then, the computation of marginal likelihoods and Bayes factors enable us to quantify the relative plausibility between the alternative mechanisms. We find that, in general, the evidence is not large enough to support a single particular damping mechanism as the most plausible one. Resonant absorption and wave leakage offer the most probable explanations in strong damping regimes, while phase mixing is the best candidate for weak/moderate damping. When applied to a selection of 89 observed transverse loop oscillations, with their corresponding measurements of damping timescales and taking into account data uncertainties, we find that positive evidence for a given damping mechanism is only available in a few cases.

  3. MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

    2009-01-01

    The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

  4. Propagation of magnetoacoustic waves in the solar atmosphere with random inhomogeneities of density and magnetic fields

    International Nuclear Information System (INIS)

    Ryutova, M.

    1990-08-01

    Effects of strong and random inhomogeneities of the magnetic fields, plasma density, and temperature in the solar atmosphere on the properties of magnetoacoustic waves of arbitrary amplitudes are studied. The procedure which allows one to obtain the averaged equation containing the nonlinearity of a wave, dispersion properties of a system, and dissipative effects is described. It is shown that depending on the statistical properties of the medium, different scenarios of wave propagation arise: in the predominance of dissipative effects the primary wave is damped away in the linear stage and the efficiency of heating due to inhomogeneities is much greater than that in homogeneous medium. Depending on the interplay of nonlinear and dispersion effects, the process of heating can be afforded through the formation of shocks or through the storing of energy in a system of solitons which are later damped away. Our computer simulation supports and extends the above theoretical investigations. In particular the enhanced dissipation of waves due to the strong and random inhomogeneities is observed and this is more pronounced for shorter waves

  5. Resonant acceleration of alpha particles by ion cyclotron waves in the solar wind

    Science.gov (United States)

    Gomberoff, L.; Elgueta, R.

    1991-06-01

    Preferential acceleration of alpha particles interacting with left-hand polarized ion cyclotron waves is studied. It is shown that a small positive drift velocity between alpha particles and protons can lead to alpha particle velocities well in excess of the proton bulk velocity. During the acceleration process, which is assumed to take place at heliocentric distances less than 0.3 AU, the alpha particle drift velocity should exceed the proton bulk velocity, and then the gap which exists around the alpha particle gyrofrequency should disappear. It is also shown that for proton thermal anisotropies of the order of those observed in fast solar wind, the waves either grow or are not damped excessively, so that the waves can exist and might thus lead to the observed differential speeds. However, the way in which the alpha particles exceed the proton velocity remains unexplained.

  6. A study of shock-associated magnetohydrodynamic waves in the solar wind

    Science.gov (United States)

    Spangler, Steven R.

    1992-01-01

    Three major topics were addressed, one theoretical and two observational. The topics were: (1) an attempt to understand the evolution of the large-amplitude magnetohydrodynamic (MHD) waves in the foreshock, using a nonlinear wave equation called the Derivative Nonlinear Schrodinger equation (henceforth DNLS) as a model, (2) using the extensive set of ISE data to test for the presence of various nonlinear wave processes which might be present, and (3) a study of plasma turbulence in the interstellar medium which might be physically similar to that in the solar wind. For these investigations we used radioastronomical techniques. Good progress was made in each of these areas and a separate discussion of each is given.

  7. Resonators for magnetohydrodynamic waves in the solar corona: The effect of modulation of radio emission

    International Nuclear Information System (INIS)

    Zaitsev, V.V.; Stepanov, A.V.

    1982-01-01

    It is shown that the existence of a minimum of the Alfven speed in the corona at a height of approx.1R/sub sun/ follows from the characteristics of type II radio bursts. The region of a reduced Alfven speed is a resonator for a fast magnetosonic (FMS) waves. The eigenmodes of the resonator are determined. The period of the fundamental mode has the order of several minutes. In the resonator FMS waves can be excited at the Cherenkov resonance by streams of energetic ions. Modulations of metal solar radio emission with a period of several minutes is explained by the effect of the propagation of radio waves through an oscillating magnetohydrodynamic (MHD) resonator

  8. A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind

    Science.gov (United States)

    Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Vinas, A.; Jian, L. K.; Roberts, D. A.; O’Modhrain, S.; Gilbert, J. A.; hide

    2016-01-01

    We use audification of 0.092 seconds cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes greater than 0.1 nanoteslas near the ion gyrofrequency (approximately 0.1 hertz) with duration longer than 1 hour during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.

  9. MHD Wave Propagation at the Interface Between Solar Chromosphere and Corona

    Science.gov (United States)

    Huang, Y.; Song, P.; Vasyliunas, V. M.

    2017-12-01

    We study the electromagnetic and momentum constraints at the solar transition region which is a sharp layer interfacing between the solar chromosphere and corona. When mass transfer between the two domains is neglected, the transition region can be treated as a contact discontinuity across which the magnetic flux is conserved and the total forces are balanced. We consider an Alfvénic perturbation that propagates along the magnetic field incident onto the interface from one side. In order to satisfy the boundary conditions at the transition region, only part of the incident energy flux is transmitted through and the rest is reflected. Taking into account the highly anisotropic propagation of waves in magnetized plasmas, we generalize the law of reflection and specify Snell's law for each of the three wave MHD modes: incompressible Alfvén mode and compressible fast and slow modes. Unlike conventional optical systems, the interface between two magnetized plasmas is not rigid but can be deformed by the waves, allowing momentum and energy to be transferred by compression. With compressible modes included, the Fresnel conditions need substantial modification. We derive Fresnel conditions, reflectivities and transmittances, and mode conversion for incident waves propagating along the background magnetic field. The results are well organized when the incident perturbation is decomposed into components in and normal to the incident plane (containing the background magnetic field and the normal direction of the interface). For a perturbation normal to the incident plane, both transmitted and reflected perturbations are incompressible Alfvén mode waves. For a perturbation in the incident plane, they can be compressible slow and fast mode waves which may produce ripples on the transition region.

  10. Short-Term Wave Forecasting with AR models in Real-Time Optimal Control of Wave Energy Converters

    OpenAIRE

    Fusco, Francesco; Ringwood, John

    2010-01-01

    Time domain control of wave energy converters requires knowledge of future incident wave elevation in order to approach conditions for optimal energy extraction. Autoregressive models revealed to be a promising approach to the prediction of future values of the wave elevation only from its past history. Results on real wave observations from different ocean locations show that AR models allow to achieve very good predictions for more than one wave period in the future if ...

  11. Variety identification of brown sugar using short-wave near infrared spectroscopy and multivariate calibration

    Science.gov (United States)

    Yang, Haiqing; Wu, Di; He, Yong

    2007-11-01

    Near-infrared spectroscopy (NIRS) with the characteristics of high speed, non-destructiveness, high precision and reliable detection data, etc. is a pollution-free, rapid, quantitative and qualitative analysis method. A new approach for variety discrimination of brown sugars using short-wave NIR spectroscopy (800-1050nm) was developed in this work. The relationship between the absorbance spectra and brown sugar varieties was established. The spectral data were compressed by the principal component analysis (PCA). The resulting features can be visualized in principal component (PC) space, which can lead to discovery of structures correlative with the different class of spectral samples. It appears to provide a reasonable variety clustering of brown sugars. The 2-D PCs plot obtained using the first two PCs can be used for the pattern recognition. Least-squares support vector machines (LS-SVM) was applied to solve the multivariate calibration problems in a relatively fast way. The work has shown that short-wave NIR spectroscopy technique is available for the brand identification of brown sugar, and LS-SVM has the better identification ability than PLS when the calibration set is small.

  12. Survey of exposure of physiotherapist operators to emissions from microwave and short wave diathermy equipment

    International Nuclear Information System (INIS)

    Coppell, R.B.

    1987-01-01

    An extensive survey of levels of electromagnetic fields in the vicinity of microwave and short wave diathermy equipment is presented and occupational exposure of physiotherapist operators is assessed. There was a good response to mailed questionnaires to 18 hospital boards, 21 private hospitals, and 148 private physiotherapy practices in Christchruch and centres of the north island of New Zealand. Within 34 public hospitals and 57 private practice of those so contacted, who also volunteered to participate, measurements were made in numerous positions about operating equipment. For practical reasons, manufactured phantom sections were substituted for real patients. Levels of microwave power flux density were found to vary according to position and to orientation of equipment and patient phantom. Provided, microwave diathermy equipment is used with reasonable care, excessive exposure of the physiotherapist operator is considered very unlikely. Levels of electric and magnetic field strength squared in the vicinity of simulated body sections under short wave diathermy treatment were found to be highly localised and strongly dependent upon the type of applicator used and the proximity of connecting leads. Operating procedures, including distances of separation, are recommended to protect operators from excessive exposure. (author). 30 refs., 8 tabs., 4 figs., ills

  13. Generation of type III solar radio bursts: the role of induced scattering of plasma waves by ions

    International Nuclear Information System (INIS)

    Levin, B.N.; Lerner, A.M.; Rapoport, V.O.

    1984-01-01

    The plasma waves in type III solar radio-burst sources might have a spectrum which can explain why, in the quasilinear burst generation model, nonlinear scattering of the waves by ions is so weak. The agent exciting a burst would travel through the corona at velocities limited to a definite range

  14. Characterizing a Model of Coronal Heating and Solar Wind Acceleration Based on Wave Turbulence.

    Science.gov (United States)

    Downs, C.; Lionello, R.; Mikic, Z.; Linker, J.; Velli, M.

    2014-12-01

    Understanding the nature of coronal heating and solar wind acceleration is a key goal in solar and heliospheric research. While there have been many theoretical advances in both topics, including suggestions that they may be intimately related, the inherent scale coupling and complexity of these phenomena limits our ability to construct models that test them on a fundamental level for realistic solar conditions. At the same time, there is an ever increasing impetus to improve our spaceweather models, and incorporating treatments for these processes that capture their basic features while remaining tractable is an important goal. With this in mind, I will give an overview of our exploration of a wave-turbulence driven (WTD) model for coronal heating and solar wind acceleration based on low-frequency Alfvénic turbulence. Here we attempt to bridge the gap between theory and practical modeling by exploring this model in 1D HD and multi-dimensional MHD contexts. The key questions that we explore are: What properties must the model possess to be a viable model for coronal heating? What is the influence of the magnetic field topology (open, closed, rapidly expanding)? And can we simultaneously capture coronal heating and solar wind acceleration with such a quasi-steady formulation? Our initial results suggest that a WTD based formulation performs adequately for a variety of solar and heliospheric conditions, while significantly reducing the number of free parameters when compared to empirical heating and solar wind models. The challenges, applications, and future prospects of this type of approach will also be discussed.

  15. Analytic Approximations for Soliton Solutions of Short-Wave Models for Camassa-Holm and Degasperis-Procesi Equations

    International Nuclear Information System (INIS)

    Yang Pei; Li Zhibin; Chen Yong

    2010-01-01

    In this paper, the short-wave model equations are investigated, which are associated with the Camassa-Holm (CH) and Degasperis-Procesi (DP) shallow-water wave equations. Firstly, by means of the transformation of the independent variables and the travelling wave transformation, the partial differential equation is reduced to an ordinary differential equation. Secondly, the equation is solved by homotopy analysis method. Lastly, by the transformations back to the original independent variables, the solution of the original partial differential equation is obtained. The two types of solutions of the short-wave models are obtained in parametric form, one is one-cusp soliton for the CH equation while the other one is one-loop soliton for the DP equation. The approximate analytic solutions expressed by a series of exponential functions agree well with the exact solutions. It demonstrates the validity and great potential of homotopy analysis method for complicated nonlinear solitary wave problems. (general)

  16. Generation of thermo-acoustic waves from pulsed solar/IR radiation

    Science.gov (United States)

    Rahman, Aowabin

    Acoustic waves could potentially be used in a wide range of engineering applications; however, the high energy consumption in generating acoustic waves from electrical energy and the cost associated with the process limit the use of acoustic waves in industrial processes. Acoustic waves converted from solar radiation provide a feasible way of obtaining acoustic energy, without relying on conventional nonrenewable energy sources. One of the goals of this thesis project was to experimentally study the conversion of thermal to acoustic energy using pulsed radiation. The experiments were categorized into "indoor" and "outdoor" experiments, each with a separate experimental setup. The indoor experiments used an IR heater to power the thermo-acoustic lasers and were primarily aimed at studying the effect of various experimental parameters on the amplitude of sound waves in the low frequency range (below 130 Hz). The IR radiation was modulated externally using a chopper wheel and then impinged on a porous solid, which was housed inside a thermo-acoustic (TA) converter. A microphone located at a certain distance from the porous solid inside the TA converter detected the acoustic signals. The "outdoor" experiments, which were targeted at TA conversion at comparatively higher frequencies (in 200 Hz-3 kHz range) used solar energy to power the thermo-acoustic laser. The amplitudes (in RMS) of thermo-acoustic signals obtained in experiments using IR heater as radiation source were in the 80-100 dB range. The frequency of acoustic waves corresponded to the frequency of interceptions of the radiation beam by the chopper. The amplitudes of acoustic waves were influenced by several factors, including the chopping frequency, magnitude of radiation flux, type of porous material, length of porous material, external heating of the TA converter housing, location of microphone within the air column, and design of the TA converter. The time-dependent profile of the thermo-acoustic signals

  17. Ion Acoustic Wave Frequencies and Onset Times During Type 3 Solar Radio Bursts

    Science.gov (United States)

    Cairns, Iver H.; Robinson, P. A.

    1995-01-01

    Conflicting interpretations exist for the low-frequency ion acoustic (S) waves often observed by ISEE 3 in association with intense Langmuir (L) waves in the source regions of type III solar radio bursts near 1 AU. Two indirect lines of observational evidence, as well as plasma theory, suggest they are produced by the electrostatic (ES) decay L yields L(PRIME) + S. However, contrary to theoretical predictions, an existing analysis of the wave frequencies instead favors the electromagnetic (EM) decays L yields T + S, where T denotes an EM wave near the plasma frequency. This conflict is addressed here by comparing the observed wave frequencies and onset times with theoretical predictions for the ES and EM decays, calculated using the time-variable electron beam and magnetic field orientation data, rather than the nominal values used previously. Field orientation effects and beam speed variations are shown analytically to produce factor-of-three effects, greater than the difference in wave frequencies predicted for the ES and EM decays; effects of similar magnitude occur in the events analyzed here. The S-wave signals are extracted by hand from a sawtooth noise background, greatly improving the association between S waves and intense L waves. Very good agreement exists between the time-varying predictions for the ES decay and the frequencies of most (but not all) wave bursts. The waves occur only after the ES decay becomes kinematically allowed, which is consistent with the ES decay proceeding and producing most of the observed signals. Good agreement exists between the EM decay's predictions and a significant fraction of the S-wave observations while the EM decay is kinematically allowed. The wave data are not consistent, however, with the EM decay being the dominant nonlinear process. Often the observed waves are sufficiently broadband to overlap simultaneously the frequency ranges predicted for the ES and EM decays. Coupling the dominance of the ES decay with this

  18. Short-Term Solar Irradiance Forecasts Using Sky Images and Radiative Transfer Model

    Directory of Open Access Journals (Sweden)

    Juan Du

    2018-05-01

    Full Text Available In this paper, we propose a novel forecast method which addresses the difficulty in short-term solar irradiance forecasting that arises due to rapidly evolving environmental factors over short time periods. This involves the forecasting of Global Horizontal Irradiance (GHI that combines prediction sky images with a Radiative Transfer Model (RTM. The prediction images (up to 10 min ahead are produced by a non-local optical flow method, which is used to calculate the cloud motion for each pixel, with consecutive sky images at 1 min intervals. The Direct Normal Irradiance (DNI and the diffuse radiation intensity field under clear sky and overcast conditions obtained from the RTM are then mapped to the sky images. Through combining the cloud locations on the prediction image with the corresponding instance of image-based DNI and diffuse radiation intensity fields, the GHI can be quantitatively forecasted for time horizons of 1–10 min ahead. The solar forecasts are evaluated in terms of root mean square error (RMSE and mean absolute error (MAE in relation to in-situ measurements and compared to the performance of the persistence model. The results of our experiment show that GHI forecasts using the proposed method perform better than the persistence model.

  19. Spectral analysis to detection of short circuit fault of solar photovoltaic modules in strings

    International Nuclear Information System (INIS)

    Sevilla-Camacho, P.Y.; Robles-Ocampo, J.B.; Zuñiga-Reyes, Marco A.

    2017-01-01

    This research work presents a method to detect the number of short circuit faulted solar photovoltaic modules in strings of a photovoltaic system by taking into account speed, safety, and non-use of sensors and specialized and expensive equipment. The method consists on apply the spectral analysis and statistical techniques to the alternating current output voltage of a string and detect the number of failed modules through the changes in the amplitude of the component frequency of 12 kHz. For that, the analyzed string is disconnected of the array; and a small pulsed voltage signal of frequency of 12 kHz introduces him under dark condition and controlled temperature. Previous to the analysis, the signal is analogic filtered in order to reduce the direct current signal component. The spectral analysis technique used is the Fast Fourier Transform. The obtained experimental results were validated through simulation of the alternating current equivalent circuit of a solar cell. In all experimental and simulated test, the method allowed to identify correctly the number of photovoltaic modules with short circuit in the analyzed string. (author)

  20. Up-Wave and Autoregressive Methods for Short-Term Wave Forecasting for an Oscillating Water Column

    OpenAIRE

    Paparella, Francesco; Monk, Kieran; Winands, Victor; Lopes, M.F.P.; Conley, Daniel; Ringwood, John

    2015-01-01

    The real-time control of wave energy converters (WECs) requires the prediction of the wave elevation at the location of the device in order to maximize the power extracted from the waves. One possibility is to predict the future wave elevation by combining its past history with the spatial information coming from a sensor which measures the free surface elevation up-wave of the WEC. As an application example, this paper focuses on the prediction of the wave elevation inside the chamber of the...

  1. THE CHROMOSPHERIC SOLAR MILLIMETER-WAVE CAVITY ORIGINATES IN THE TEMPERATURE MINIMUM REGION

    Energy Technology Data Exchange (ETDEWEB)

    De la Luz, Victor [Instituto Nacional de Astrofisica, Optica y Electronica, Tonantzintla, Puebla, Mexico, Apdo. Postal 51 y 216, 72000 (Mexico); Raulin, Jean-Pierre [CRAAM, Universidade Presbiteriana Mackenzie, Sao Paulo, SP 01302-907 (Brazil); Lara, Alejandro [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Mexico 04510 (Mexico)

    2013-01-10

    We present a detailed theoretical analysis of the local radio emission at the lower part of the solar atmosphere. To accomplish this, we have used a numerical code to simulate the emission and transport of high-frequency electromagnetic waves from 2 GHz up to 10 THz. As initial conditions, we used VALC, SEL05, and C7 solar chromospheric models. In this way, the generated synthetic spectra allow us to study the local emission and absorption processes with high resolution in both altitude and frequency. Associated with the temperature minimum predicted by these models, we found that the local optical depth at millimeter wavelengths remains constant, producing an optically thin layer that is surrounded by two layers of high local emission. We call this structure the Chromospheric Solar Millimeter-wave Cavity (CSMC). The temperature profile, which features temperature minimum layers and a subsequent temperature rise, produces the CSMC phenomenon. The CSMC shows the complexity of the relation between the theoretical temperature profile and the observed brightness temperature and may help us to understand the dispersion of the observed brightness temperature in the millimeter wavelength range.

  2. ERRATUM: Propagating Waves Transverse to the Magnetic Field in a Solar Prominence

    Science.gov (United States)

    Schmieder, B.; Kucera, T. A.; Knizhnik, K.; Luna, M.; Lopez-Ariste, A.; Toot, D.

    2014-01-01

    We report an unusual set of observations of waves in a large prominence pillar that consist of pulses propagating perpendicular to the prominence magnetic field. We observe a huge quiescent prominence with the Solar Dynamics Observatory Atmospheric Imaging Assembly in EUV on 2012 October 10 and only a part of it, the pillar, which is a foot or barb of the prominence, with the Hinode Solar Optical Telescope (SOT; in Ca II and Halpha lines), Sac Peak (in Ha, Hß, and Na-D lines), and THEMIS ("Télescope Héliographique pour l' Etude du Magnétisme et des Instabilités Solaires") with the MTR (MulTi-Raies) spectropolarimeter (in He D3 line). The THEMIS/MTR data indicates that the magnetic field in the pillar is essentially horizontal and the observations in the optical domain show a large number of horizontally aligned features on a much smaller scale than the pillar as a whole. The data are consistent with a model of cool prominence plasma trapped in the dips of horizontal field lines. The SOT and Sac Peak data over the four hour observing period show vertical oscillations appearing as wave pulses. These pulses, which include a Doppler signature, move vertically, perpendicular to the field direction, along thin quasi-vertical columns in the much broader pillar. The pulses have a velocity of propagation of about 10 km/s, a period of about 300 s, and a wavelength around 2000 km. We interpret these waves in terms of fast magnetosonic waves and discuss possible wave drivers.

  3. PROPAGATING WAVES TRANSVERSE TO THE MAGNETIC FIELD IN A SOLAR PROMINENCE

    Energy Technology Data Exchange (ETDEWEB)

    Schmieder, B. [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon (France); Kucera, T. A.; Knizhnik, K. [Code 671, NASA' s GSFC, Greenbelt, MD 20771 (United States); Luna, M. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Lopez-Ariste, A. [THEMIS, CNRS-UPS853, E-38205 La Laguna (Spain); Toot, D. [Alfred University, Alfred, NY 14802 (United States)

    2013-11-10

    We report an unusual set of observations of waves in a large prominence pillar that consist of pulses propagating perpendicular to the prominence magnetic field. We observe a huge quiescent prominence with the Solar Dynamics Observatory Atmospheric Imaging Assembly in EUV on 2012 October 10 and only a part of it, the pillar, which is a foot or barb of the prominence, with the Hinode Solar Optical Telescope (SOT; in Ca II and Hα lines), Sac Peak (in Hα, Hβ, and Na-D lines), and THEMIS ({sup T}élescope Héliographique pour l' Etude du Magnétisme et des Instabilités Solaires{sup )} with the MTR (MulTi-Raies) spectropolarimeter (in He D{sub 3} line). The THEMIS/MTR data indicates that the magnetic field in the pillar is essentially horizontal and the observations in the optical domain show a large number of horizontally aligned features on a much smaller scale than the pillar as a whole. The data are consistent with a model of cool prominence plasma trapped in the dips of horizontal field lines. The SOT and Sac Peak data over the four hour observing period show vertical oscillations appearing as wave pulses. These pulses, which include a Doppler signature, move vertically, perpendicular to the field direction, along thin quasi-vertical columns in the much broader pillar. The pulses have a velocity of propagation of about 10 km s{sup –1}, a period of about 300 s, and a wavelength around 2000 km. We interpret these waves in terms of fast magnetosonic waves and discuss possible wave drivers.

  4. EXPLAINING INVERTED-TEMPERATURE LOOPS IN THE QUIET SOLAR CORONA WITH MAGNETOHYDRODYNAMIC WAVE-MODE CONVERSION

    Energy Technology Data Exchange (ETDEWEB)

    Schiff, Avery J.; Cranmer, Steven R. [Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309 (United States)

    2016-11-01

    Coronal loops trace out bipolar, arch-like magnetic fields above the Sun’s surface. Recent measurements that combine rotational tomography, extreme-ultraviolet imaging, and potential-field extrapolation have shown the existence of large loops with inverted-temperature profiles, i.e., loops for which the apex temperature is a local minimum, not a maximum. These “down loops” appear to exist primarily in equatorial quiet regions near solar minimum. We simulate both these and the more prevalent large-scale “up loops” by modeling coronal heating as a time-steady superposition of (1) dissipation of incompressible Alfvén wave turbulence and (2) dissipation of compressive waves formed by mode conversion from the initial population of Alfvén waves. We found that when a large percentage (>99%) of the Alfvén waves undergo this conversion, heating is greatly concentrated at the footpoints and stable “down loops” are created. In some cases we found loops with three maxima that are also gravitationally stable. Models that agree with the tomographic temperature data exhibit higher gas pressures for “down loops” than for “up loops,” which is consistent with observations. These models also show a narrow range of Alfvén wave amplitudes: 3 to 6 km s{sup -1} at the coronal base. This is low in comparison to typical observed amplitudes of 20–30 km s{sup -1} in bright X-ray loops. However, the large-scale loops we model are believed to compose a weaker diffuse background that fills much of the volume of the corona. By constraining the physics of loops that underlie quiescent streamers, we hope to better understand the formation of the slow solar wind.

  5. Association of time structures of solar bursts at millimetric waves and at metric waves

    International Nuclear Information System (INIS)

    Sawant, H.S.; Kaufmann, P.; Correia, E.; Costa, J.E.R.; Zlobec, P.; Messerotti, M.; Fornasari, L.

    Due to the lack of simultaneous high sensitivity/time resolution observations at mm-lambda, cm-lambda and m-lambda a program on such investigations has been carried out with data obtained by INPE at Itapetinga and by the Astronomical Observatory of Trieste. Preliminary results obtained by comparing mm-wave burst structures with 408, 327 and 237 MHz indicate that i) for majority of major time structures (time scales of the order of 1 sec) observed at 22 GHz bursts, corresponding type III bursts have been observed at 237 Mhz, however ii) start times at mm-lambda and m-lambda are not often coincident at two wavelengths. These observations favour the hypothesis of (a) time dependent acceleration of energetic electrons and (b) burst emission is the response to a multiple injection of energetic electrons. (Author) [pt

  6. The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Mijie; Xiao, Chijie; Wang, Xiaogang [State Key Laboratory of Nuclear Physics and Technology, Fusion Simulation Center, School of Physics, Peking University, Beijing 100871 (China); Li, Hui, E-mail: cjxiao@pku.edu.cn [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2017-06-10

    We perform three-dimensional ideal magnetohydrodynamic (MHD) simulations to study the parametric decay instability (PDI) of Alfvén waves in turbulent plasmas and explore its possible applications in the solar wind. We find that, over a broad range of parameters in background turbulence amplitudes, the PDI of an Alfvén wave with various amplitudes can still occur, though its growth rate in turbulent plasmas tends to be lower than both the theoretical linear theory prediction and that in the non-turbulent situations. Spatial–temporal FFT analyses of density fluctuations produced by the PDI match well with the dispersion relation of the slow MHD waves. This result may provide an explanation of the generation mechanism of slow waves in the solar wind observed at 1 au. It further highlights the need to explore the effects of density variations in modifying the turbulence properties as well as in heating the solar wind plasmas.

  7. Search for gravitational waves on short duration in TAMA300 data: stellar core collapse and black hole

    International Nuclear Information System (INIS)

    Honda, R; Kanda, N; Akutsu, T; Ando, M; Tsunesada, Y

    2008-01-01

    We present in the results of TAMA300 data analysis for short duration gravitational waves. The excess power filter, alternative linear filter (ALF) and TF(time-frequency) clustering methods have been employed for burst gravitational waves from stellar-core collapse, and matched filtering method used for the ringdown gravitational waves from black hole quasi-normal oscillations. The observational range of TAMA for the burst gravitational waves is roughly ∼ 1 kpc, and the range for black hole ringdown covers most of our galaxy. We have been developed new method 'time-frequency (TF) clustering' to find the burst waves. This is a TF clustering method on spectrogram (sonogram). Using this method, we can efficiently identify some predicted gravitational wave forms and can exclude typical unstable spike like noises

  8. “Dandelion” Filament Eruption and Coronal Waves Associated with a Solar Flare on 2011 February 16

    International Nuclear Information System (INIS)

    Cabezas, Denis P.; Ishitsuka, Mutsumi; Ishitsuka, José K.; Martínez, Lurdes M.; Buleje, Yovanny J.; Morita, Satoshi; Asai, Ayumi; UeNo, Satoru; Ishii, Takako T.; Kitai, Reizaburo; Takasao, Shinsuke; Yoshinaga, Yusuke; Otsuji, Kenichi; Shibata, Kazunari

    2017-01-01

    Coronal disturbances associated with solar flares, such as H α Moreton waves, X-ray waves, and extreme ultraviolet (EUV) coronal waves, are discussed herein in relation to magnetohydrodynamic fast-mode waves or shocks in the corona. To understand the mechanism of coronal disturbances, full-disk solar observations with high spatial and temporal resolution over multiple wavelengths are of crucial importance. We observed a filament eruption, whose shape is like a “dandelion,” associated with the M1.6 flare that occurred on 2011 February 16 in H α images taken by the Flare Monitoring Telescope at Ica University, Peru. We derive the three-dimensional velocity field of the erupting filament. We also identify winking filaments that are located far from the flare site in the H α images, whereas no Moreton wave is observed. By comparing the temporal evolution of the winking filaments with those of the coronal wave seen in the EUV images data taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and by the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory-Ahead , we confirm that the winking filaments were activated by the EUV coronal wave.

  9. “Dandelion” Filament Eruption and Coronal Waves Associated with a Solar Flare on 2011 February 16

    Energy Technology Data Exchange (ETDEWEB)

    Cabezas, Denis P.; Ishitsuka, Mutsumi; Ishitsuka, José K. [Geophysical Institute of Peru, Calle Badajoz 169, Mayorazgo IV Etapa, Ate Vitarte, Lima (Peru); Martínez, Lurdes M.; Buleje, Yovanny J. [Centro de Investigación del Estudio de la Actividad Solar y sus Efectos Sobre la Tierra, Facultad de Ciencias, Universidad Nacional San Luis Gonzaga de Ica, Av. Los Maestros S/N, Ica (Peru); Morita, Satoshi [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Asai, Ayumi [Unit of Synergetic Studies for Space, Kyoto University, Sakyo, Kyoto, 606-8502 (Japan); UeNo, Satoru; Ishii, Takako T.; Kitai, Reizaburo; Takasao, Shinsuke; Yoshinaga, Yusuke; Otsuji, Kenichi; Shibata, Kazunari, E-mail: denis@kwasan.kyoto-u.ac.jp [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan)

    2017-02-10

    Coronal disturbances associated with solar flares, such as H α Moreton waves, X-ray waves, and extreme ultraviolet (EUV) coronal waves, are discussed herein in relation to magnetohydrodynamic fast-mode waves or shocks in the corona. To understand the mechanism of coronal disturbances, full-disk solar observations with high spatial and temporal resolution over multiple wavelengths are of crucial importance. We observed a filament eruption, whose shape is like a “dandelion,” associated with the M1.6 flare that occurred on 2011 February 16 in H α images taken by the Flare Monitoring Telescope at Ica University, Peru. We derive the three-dimensional velocity field of the erupting filament. We also identify winking filaments that are located far from the flare site in the H α images, whereas no Moreton wave is observed. By comparing the temporal evolution of the winking filaments with those of the coronal wave seen in the EUV images data taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and by the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory-Ahead , we confirm that the winking filaments were activated by the EUV coronal wave.

  10. Recent Successes of Wave/Turbulence Driven Models of Solar Wind Acceleration

    Science.gov (United States)

    Cranmer, S. R.; Hollweg, J. V.; Chandran, B. D.; van Ballegooijen, A. A.

    2010-12-01

    A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a first-principles understanding of coronal heating. Also, it is still unknown whether the solar wind is "fed" through flux tubes that remain open (and are energized by footpoint-driven wavelike fluctuations) or if mass and energy are input intermittently from closed loops into the open-field regions. In this presentation, we discuss self-consistent models that assume the energy comes from solar Alfven waves that are partially reflected, and then dissipated, by magnetohydrodynamic turbulence. These models have been found to reproduce many of the observed features of the fast and slow solar wind without the need for artificial "coronal heating functions" used by earlier models. For example, the models predict a variation with wind speed in commonly measured ratios of charge states and elemental abundances that agrees with observed trends. This contradicts a commonly held assertion that these ratios can only be produced by the injection of plasma from closed-field regions on the Sun. This presentation also reviews two recent comparisons between the models and empirical measurements: (1) The models successfully predict the amplitude and radial dependence of Faraday rotation fluctuations (FRFs) measured by the Helios probes for heliocentric distances between 2 and 15 solar radii. The FRFs are a particularly sensitive test of turbulence models because they depend not only on the plasma density and Alfven wave amplitude in the corona, but also on the turbulent correlation length. (2) The models predict the correct sense and magnitude of changes seen in the polar high-speed solar wind by Ulysses from the previous solar minimum (1996-1997) to the more recent peculiar minimum (2008-2009). By changing only the magnetic field along the polar magnetic flux tube, consistent with solar and heliospheric observations at the two epochs, the model correctly predicts that the

  11. Relating Alfvén Wave Heating Model to Observations of a Solar Active Region

    Science.gov (United States)

    Yoritomo, J. Y.; Van Ballegooijen, A. A.

    2012-12-01

    We compared images from the Solar Dynamics Observatory's (SDO) Atmospheric Imaging Assembly (AIA) with simulations of propagating and dissipating Alfvén waves from a three-dimensional magnetohydrodynamic (MHD) model (van Ballegooijen et. al 2011; Asgari-Targhi & van Ballegooijen 2012). The goal was to search for observational evidence of Alfvén waves in the solar corona and understand their role in coronal heating. We looked at one particular active region on the 5th of May 2012. Certain distinct loops in the SDO/AIA observations were selected and expanded. Movies were created from these selections in an attempt to discover transverse motions that may be Alfvén waves. Using a magnetogram of that day and the corresponding synoptic map, a potential field model was created for the active region. Three-dimensional MHD models for several loops in different locations in the active region were created. Each model specifies the temperature, pressure, magnetic field strength, average heating rate, and other parameters along the loop. We find that the heating is intermittent in the loops and reflection occurs at the transition region. For loops at larger and larger height, a point is reached where thermal non-equilibrium occurs. In the center this critical height is much higher than in the periphery of the active region. Lastly, we find that the average heating rate and coronal pressure decrease with increasing height in the corona. This research was supported by an NSF grant for the Smithsonian Astrophysical Observatory (SAO) Solar REU program and a SDO/AIA grant for the Smithsonian Astrophysical Observatory.

  12. Statistical Study of Low-Frequency Electromagnetic Cyclotron Waves in the Solar Wind at 1 AU

    Science.gov (United States)

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

    2018-03-01

    Electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency are common wave activities in the solar wind and have attracted much attention in recent years. This paper investigates 82,809 ECWs based on magnetic field data from the Solar Terrestrial Relations Observatory-A mission between 2007 and 2013. Results show that ECWs may last for just a few seconds or incessantly for several tens of minutes. The time fraction of ECW storms among all solar wind is about 0.9%; the storms are obtained with the duration threshold of 10 min, amplitude criterion of 0.032 nT, and time separation limit of 3 min for combination of intermittent ECWs. Most of ECWs have their amplitudes less than 1 nT, while some ECWs have large amplitudes comparable to the ambient magnetic field. The distributions of the durations and amplitudes of these ECWs are characterized by power law spectra, respectively, with spectrum indexes around 4. Statistically, there seems to be a tendency that ECWs with a longer duration will have a larger amplitude. Observed ECW properties are time dependent, and the median frequency of left-hand ECWs can be lower than that of right-hand ECWs in some months in the spacecraft frame. The percentage of left-hand ECWs varies in a large range with respect to months; it is much low (26%) in a month, though it frequently exceeds 50% in other months. Characteristics of ECWs with concurrent polarizations are also researched. The present study should be of importance for a more complete picture of ECWs in the solar wind.

  13. A Tire Model for Off-Highway Vehicle Simulation on Short Wave Irregular Terrain

    DEFF Research Database (Denmark)

    Langer, Thomas Heegaard; Kristensen, Lars B; Mouritsen, Ole Ø.

    2010-01-01

    Manufacturers of construction machinery are challenged in several ways concerning dynamic loads. Considering off-highway dump trucks that travel through high amplitude short wave irregular terrain with considerable speed two aspects concerning dynamics are important. The first is the legal...... between simulated data and experimental data obtained from full vehicle testing. The experimental work is carried out by letting a dump truck pass a set of well defined obstacles. Based on the obtained agreement between simulated and measured results the tire model is considered suitable for describing...... joints, spring-damper elements and the welded structures it is crucial to have information on the time history of the loads. For trucks carrying payloads the most important load contribution is undoubtedly the reaction forces between terrain and tires. By use of virtual prototypes it is possible...

  14. Developments of sausages in a z-pinch with short-wave perturbation of a boundary

    International Nuclear Information System (INIS)

    Vikhrev, V.V.; Ivanov, V.V.; Rozanova, G.A.

    1989-01-01

    A numeric simulation of sausage evolution in z-pinch during short-wave excitation of the boundary of plasma column pinch is carried out. The simulation has shown that due to nonlinear development of sausages in a pinch plasma colomn the cavities filled with a magnetic field in a rarefied pinch plasma are formed. Simultaneously compact column of tense plasma whose temperature is much higher than the average temperature of pinch plasma column are formed on the pinch axis. In the region of inlet in the cavity plasma is radially directed due to ponderomotoric force 1/2 x jB up to velocities greatly increasing the thermal velocity of ions in a plasma column

  15. SPATIAL DISTRIBUTIONS OF ABSORPTION, LOCAL SUPPRESSION, AND EMISSIVITY REDUCTION OF SOLAR ACOUSTIC WAVES IN MAGNETIC REGIONS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Yang, M.-H.; Zhao Hui; Liang Zhichao; Sun, M.-T.

    2009-01-01

    Observed acoustic power in magnetic regions is lower than the quiet Sun because of absorption, emissivity reduction, and local suppression of solar acoustic waves in magnetic regions. In the previous studies, we have developed a method to measure the coefficients of absorption, emissivity reduction, and local suppression of sunspots. In this study, we go one step further to measure the spatial distributions of three coefficients in two active regions, NOAA 9055 and 9057. The maps of absorption, emissivity reduction, and local suppression coefficients correlate with the magnetic map, including plage regions, except the emissivity reduction coefficient of NOAA 9055 where the emissivity reduction coefficient is too weak and lost among the noise.

  16. Propagation of interplanetary shock waves by observations of type II solar radio bursts on IMP-6

    International Nuclear Information System (INIS)

    Chertok, I.M.; Fomichev, V.V.

    1976-01-01

    A new interpretation of the low frequency type II solar radio bursts of 30 June 1971, and 7-8 August 1972 observed with IMP-6 satellite (Malitson, H.H., Fainberg, J. and Stone, R.G., 1973, Astrophys. Lett., vol. 14, 111; Astrophys. J., vol. 183, L35) is suggested. The analysis is carried out for two models of the electron density distribution in the interplanetary medium taking into account that N approximately 3.5 cm -3 at a distance of 1 a.u. It is assumed that the frequency of the radio emission corresponds to the average electron density behind the shock front which exceeds the undisturbed electron density by the factor of 3. The radio data indicate essential deceleration of the shock waves during propagation from the Sun up to 1 a.u. The characteristics of the shock waves obtained from the type II bursts agree with the results of the in situ observations. (author)

  17. 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.

  18. A practical approach to compute short-wave irradiance interacting with subgrid-scale buildings

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Uwe; Frueh, Barbara [Deutscher Wetterdienst, Offenbach am Main (Germany)

    2012-08-15

    A numerical approach for the calculation of short-wave irradiances at the ground as well as the walls and roofs of buildings in an environment with unresolved built-up is presented. In this radiative parameterization scheme the properties of the unresolved built-up are assigned to settlement types which are characterized by mean values of the volume density of the buildings and their wall area density. Therefore it is named wall area approach. In the vertical direction the range of building heights may be subdivided into several layers. In the case of non-uniform building heights the shadowing of the lower roofs by the taller buildings is taken into account. The method includes the approximate calculation of sky view and sun view factors. For an idealized building arrangement it is shown that the obtained approximate factors are in good agreement with exact calculations just as for the comparison of the calculated and measured effective albedo values. For arrangements with isolated single buildings the presented wall area approach yields a better agreement with the observations than similar methods where the unresolved built-up is characterized by the aspect ratio of a representative street canyon (aspect ratio approach). In the limiting case where the built-up is well represented by an ensemble of idealized street canyons both approaches become equivalent. The presented short-wave radiation scheme is part of the microscale atmospheric model MUKLIMO 3 where it contributes to the calculation of surface temperatures on the basis of energy-flux equilibrium conditions. (orig.)

  19. A Case Study of Short-term Wave Forecasting Based on FIR Filter: Optimization of the Power Production for the Wavestar Device

    DEFF Research Database (Denmark)

    Ferri, Francesco; Sichani, Mahdi Teimouri; Frigaard, Peter

    2012-01-01

    Short-term wave forecasting plays a crucial role for the control of a wave energy converter (WEC), in order to increase the energy harvest from the waves, as well as to increase its life time. In the paper it is shown how the surface elevation of the waves and the force acting on the WEC can be p...

  20. THE RESPONSE OF A THREE-DIMENSIONAL SOLAR ATMOSPHERE TO WAVE-DRIVEN JETS

    Energy Technology Data Exchange (ETDEWEB)

    Scullion, E. [Institute of Theoretical Astrophysics, University of Oslo (Norway); Erdelyi, R.; Fedun, V. [Solar Physics and Space Plasma Research Centre (SP2RC), Department of Applied Mathematics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Doyle, J. G., E-mail: eamonms@astro.uio.no, E-mail: robertus@sheffield.ac.uk, E-mail: v.fedun@sheffield.ac.uk, E-mail: jgd@arm.ac.uk [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

    2011-12-10

    Global oscillations from the solar interior are, mainly, pressure-driven (p-modes) oscillations with a peak power of a five-minute period. These oscillations are considered to manifest in many phenomena in the lower solar atmosphere, most notably, in spicules. These small-scale jets may provide the key to understanding the powering mechanisms of the transition region (TR) and lower corona. Here, we simulate the formation of wave-driven (type-I) spicule phenomena in three dimensions and the transmission of acoustic waves from the lower chromosphere and into the corona. The outer atmosphere oscillates in response to the jet formation, and in turn, we reveal the formation of a circular seismic surface wave, which we name as a Transition Region Quake (TRQ). The TRQ forms as a consequence of an upward propelling spicular wave train that repeatedly punctures and energizes the TR. The steep density gradient enables the TRQ to develop and radially fan outward from the location where the spicular plasma column impinges the TR. We suggest the TRQ formation as a formidable mechanism in continuously sustaining part of the energy budget of the TR. We present a supporting numerical model which allow us to determine the level of energy dumping at the TR by upward-propagating p-modes. Upon applying a wavelet analysis on our simulations we identify the presence of a chromospheric cavity which resonates with the jet propagation and leaves behind an oscillatory wake with a distinctive periodicity. Through our numerical analysis we also discover type-I spicule turbulence leading to a convection-based motion in the low corona.

  1. ION HEATING IN INHOMOGENEOUS EXPANDING SOLAR WIND PLASMA: THE ROLE OF PARALLEL AND OBLIQUE ION-CYCLOTRON WAVES

    International Nuclear Information System (INIS)

    Ozak, N.; Ofman, L.; Viñas, A.-F.

    2015-01-01

    Remote sensing observations of coronal holes show that heavy ions are hotter than protons and their temperature is anisotropic. In-situ observations of fast solar wind streams provide direct evidence for turbulent Alfvén wave spectrum, left-hand polarized ion-cyclotron waves, and He ++ - proton drift in the solar wind plasma, which can produce temperature anisotropies by resonant absorption and perpendicular heating of the ions. Furthermore, the solar wind is expected to be inhomogeneous on decreasing scales approaching the Sun. We study the heating of solar wind ions in inhomogeneous plasma with a 2.5D hybrid code. We include the expansion of the solar wind in an inhomogeneous plasma background, combined with the effects of a turbulent wave spectrum of Alfvénic fluctuations and initial ion-proton drifts. We study the influence of these effects on the perpendicular ion heating and cooling and on the spectrum of the magnetic fluctuations in the inhomogeneous background wind. We find that inhomogeneities in the plasma lead to enhanced heating compared to the homogenous solar wind, and the generation of significant power of oblique waves in the solar wind plasma. The cooling effect due to the expansion is not significant for super-Alfvénic drifts, and is diminished further when we include an inhomogeneous background density. We reproduce the ion temperature anisotropy seen in observations and previous models, which is present regardless of the perpendicular cooling due to solar wind expansion. We conclude that small scale inhomogeneities in the inner heliosphere can significantly affect resonant wave ion heating

  2. GPS-TEC Observation of Gravity Waves Generated in the Ionosphere During 21 August 2017 Total Solar Eclipse

    Science.gov (United States)

    Nayak, Chinmaya; Yiǧit, Erdal

    2018-01-01

    The present work investigates ionospheric effects of the 21 August 2017 total solar eclipse, particularly targeting eclipse-generated gravity waves in the ionosphere. Ionospheric total electron content (TEC) derived from Global Positioning System (GPS) data obtained from a number of stations located both along and across the path of eclipse totality has been utilized for this purpose. Distinct gravity wave-like signatures with wave periods around 20-90 min (with dominant peak at 25-30 min wave period) have been observed at all locations both in the path of totality and away from it. The observed gravity waves are more intense at locations closer to the path of totality, and the wave amplitudes decrease gradually with increasing distance from the path of totality. Our result highlights the manifestation of eclipse-generated waves in the variability of the terrestrial ionosphere.

  3. Short circuit current changes in electron irradiated GaAlAs/GaAs solar cells

    Science.gov (United States)

    Walker, G. H.; Conway, E. J.

    1978-01-01

    Heteroface p-GaAlAs/p-GaAs/n-GaAs solar cells with junction depths of 0.8, 1.5, and 4 microns were irradiated with 1 MeV electrons. The short-circuit current for the 4 micron junction depth cells is significantly reduced by the electron irradiation. Reduction of the junction depth to 1.5 microns improves the electron radiation resistance of the cells while further reduction of the junction depth to 0.8 microns improves the stability of the cells even more. Primary degradation is in the blue region of the spectrum. Considerable recovery of lost response is obtained by annealing the cells at 200 C. Computer modeling shows that the degradation is caused primarily by a reduction in the minority carrier diffusion length in the p-GaAs.

  4. High short-circuit current density CdTe solar cells using all-electrodeposited semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Echendu, O.K., E-mail: oechendu@yahoo.com; Fauzi, F.; Weerasinghe, A.R.; Dharmadasa, I.M.

    2014-04-01

    CdS/CdTe and ZnS/CdTe n–n heterojunction solar cells have been fabricated using all-electrodeposited semiconductors. The best devices show remarkable high short-circuit current densities of 38.5 mAcm{sup −2} and 47.8 mAcm{sup −2}, open-circuit voltages of 630 mV and 646 mV and conversion efficiencies of 8.0% and 12.0% respectively. The major strength of these device structures lies in the combination of n–n heterojunction with a large Schottky barrier at the n-CdTe/metal back contact which provides the required band bending for the separation of photo-generated charge carriers. This is in addition to the use of a high quality n-type CdTe absorber layer with high electron mobility. The potential barrier heights estimated for these devices from the current–voltage characteristics exceed 1.09 eV and 1.13 eV for CdS/CdTe and ZnS/CdTe cells respectively. The diode rectification factors of both devices are in excess of four orders of magnitude with reverse saturation current densities of 1.0 × 10{sup −7} Acm{sup −2} and 4.0 × 10{sup −7} Acm{sup −2} respectively. These all-electrodeposited solar cell device structures are currently being studied and developed as an alternative to the well-known p–n junction structures which utilise chemical bath-deposited CdS. The preliminary material growth, device fabrication and assessment results are presented in this paper. - Highlights: • Two-electrode deposition. • High J{sub sc} Schottky barrier solar cells. • CdCl{sub 2} + CdF{sub 2} treatment.

  5. Short-Term Solar Irradiance Forecasting Model Based on Artificial Neural Network Using Statistical Feature Parameters

    Directory of Open Access Journals (Sweden)

    Hongshan Zhao

    2012-05-01

    Full Text Available Short-term solar irradiance forecasting (STSIF is of great significance for the optimal operation and power predication of grid-connected photovoltaic (PV plants. However, STSIF is very complex to handle due to the random and nonlinear characteristics of solar irradiance under changeable weather conditions. Artificial Neural Network (ANN is suitable for STSIF modeling and many research works on this topic are presented, but the conciseness and robustness of the existing models still need to be improved. After discussing the relation between weather variations and irradiance, the characteristics of the statistical feature parameters of irradiance under different weather conditions are figured out. A novel ANN model using statistical feature parameters (ANN-SFP for STSIF is proposed in this paper. The input vector is reconstructed with several statistical feature parameters of irradiance and ambient temperature. Thus sufficient information can be effectively extracted from relatively few inputs and the model complexity is reduced. The model structure is determined by cross-validation (CV, and the Levenberg-Marquardt algorithm (LMA is used for the network training. Simulations are carried out to validate and compare the proposed model with the conventional ANN model using historical data series (ANN-HDS, and the results indicated that the forecast accuracy is obviously improved under variable weather conditions.

  6. Short-Term Solar Forecasting Performance of Popular Machine Learning Algorithms: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Florita, Anthony R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Elgindy, Tarek [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hodge, Brian S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dobbs, Alex [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-10-03

    A framework for assessing the performance of short-term solar forecasting is presented in conjunction with a range of numerical results using global horizontal irradiation (GHI) from the open-source Surface Radiation Budget (SURFRAD) data network. A suite of popular machine learning algorithms is compared according to a set of statistically distinct metrics and benchmarked against the persistence-of-cloudiness forecast and a cloud motion forecast. Results show significant improvement compared to the benchmarks with trade-offs among the machine learning algorithms depending on the desired error metric. Training inputs include time series observations of GHI for a history of years, historical weather and atmospheric measurements, and corresponding date and time stamps such that training sensitivities might be inferred. Prediction outputs are GHI forecasts for 1, 2, 3, and 4 hours ahead of the issue time, and they are made for every month of the year for 7 locations. Photovoltaic power and energy outputs can then be made using the solar forecasts to better understand power system impacts.

  7. Constraints on Short, Hard Gamma-Ray Burst Beaming Angles from Gravitational Wave Observations

    Science.gov (United States)

    Williams, D.; Clark, J. A.; Williamson, A. R.; Heng, I. S.

    2018-05-01

    The first detection of a binary neutron star merger, GW170817, and an associated short gamma-ray burst confirmed that neutron star mergers are responsible for at least some of these bursts. The prompt gamma-ray emission from these events is thought to be highly relativistically beamed. We present a method for inferring limits on the extent of this beaming by comparing the number of short gamma-ray bursts (SGRBs) observed electromagnetically with the number of neutron star binary mergers detected in gravitational waves. We demonstrate that an observing run comparable to the expected Advanced LIGO (aLIGO) 2016–2017 run would be capable of placing limits on the beaming angle of approximately θ \\in (2\\buildrel{\\circ}\\over{.} 88,14\\buildrel{\\circ}\\over{.} 15), given one binary neutron star detection, under the assumption that all mergers produce a gamma-ray burst, and that SGRBs occur at an illustrative rate of {{ \\mathcal R }}grb}=10 {Gpc}}-3 {yr}}-1. We anticipate that after a year of observations with aLIGO at design sensitivity in 2020, these constraints will improve to θ \\in (8\\buildrel{\\circ}\\over{.} 10,14\\buildrel{\\circ}\\over{.} 95), under the same efficiency and SGRB rate assumptions.

  8. The binary progenitors of short and long GRBs and their gravitational-wave emission

    Directory of Open Access Journals (Sweden)

    Rueda J. A.

    2018-01-01

    Full Text Available We have sub-classified short and long-duration gamma-ray bursts (GRBs into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS or neutron star-black hole binaries (NS-BH. Long GRBs are produced via the induced gravitational collapse (IGC scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore and a NS companion. The COcore explodes as type Ic supernova (SN leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1 the role of the NS structure and the nuclear equation of state; 2 the occurrence rates obtained from X and gamma-rays observations; 3 the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

  9. The binary progenitors of short and long GRBs and their gravitational-wave emission

    Science.gov (United States)

    Rueda, J. A.; Ruffini, R.; Rodriguez, J. F.; Muccino, M.; Aimuratov, Y.; Barres de Almeida, U.; Becerra, L.; Bianco, C. L.; Cherubini, C.; Filippi, S.; Kovacevic, M.; Moradi, R.; Pisani, G. B.; Wang, Y.

    2018-01-01

    We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

  10. Background estimation in short-wave region during determination of total sample composition by x-ray fluorescence method

    International Nuclear Information System (INIS)

    Simakov, V.A.; Kordyukov, S.V.; Petrov, E.N.

    1988-01-01

    Method of background estimation in short-wave spectral region during determination of total sample composition by X-ray fluorescence method is described. 13 types of different rocks with considerable variations of base composition and Zr, Nb, Th, U content below 7x10 -3 % are investigated. The suggested method of background accounting provides for a less statistical error of the background estimation than direct isolated measurement and reliability of its determination in a short-wave region independent on the sample base. Possibilities of suggested method for artificial mixtures conforming by the content of main component to technological concemtrates - niobium, zirconium, tantalum are estimated

  11. Matlab/Simulink Implementation of Wave-based Models for Microstrip Structures utilizing Short-circuited and Opened Stubs

    Directory of Open Access Journals (Sweden)

    Biljana P. Stošić

    2011-12-01

    Full Text Available This paper describes modeling and analyzing procedures for microstrip filters based on use of one-dimensional wave digital approach. Different filter structures are observed. One filter is based on quarter-wave length short-circuited stubs and connecting transmission lines. The other one is based on cross-junction opened stubs. Frequency responses are obtained by direct analysis of the block-based networks formed in Simulink toolbox of MATLAB environment. This wave-based method allows an accurate and efficient analysis of different microwave structures.

  12. Spatially resolved determination of the short-circuit current density of silicon solar cells via lock-in thermography

    International Nuclear Information System (INIS)

    Fertig, Fabian; Greulich, Johannes; Rein, Stefan

    2014-01-01

    We present a spatially resolved method to determine the short-circuit current density of crystalline silicon solar cells by means of lock-in thermography. The method utilizes the property of crystalline silicon solar cells that the short-circuit current does not differ significantly from the illuminated current under moderate reverse bias. Since lock-in thermography images locally dissipated power density, this information is exploited to extract values of spatially resolved current density under short-circuit conditions. In order to obtain an accurate result, one or two illuminated lock-in thermography images and one dark lock-in thermography image need to be recorded. The method can be simplified in a way that only one image is required to generate a meaningful short-circuit current density map. The proposed method is theoretically motivated, and experimentally validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  13. Frequency-dependent Alfvén-wave Propagation in the Solar Wind: Onset and Suppression of Parametric Decay Instability

    Science.gov (United States)

    Shoda, Munehito; Yokoyama, Takaaki; Suzuki, Takeru K.

    2018-06-01

    Using numerical simulations we investigate the onset and suppression of parametric decay instability (PDI) in the solar wind, focusing on the suppression effect by the wind acceleration and expansion. Wave propagation and dissipation from the coronal base to 1 au is solved numerically in a self-consistent manner; we take into account the feedback of wave energy and pressure in the background. Monochromatic waves with various injection frequencies, f 0, are injected to discuss the suppression of PDI, while broadband waves are applied to compare the numerical results with observation. We find that high-frequency ({f}0≳ {10}-3 {Hz}) Alfvén waves are subject to PDI. Meanwhile, the maximum growth rate of the PDI of low-frequency ({f}0≲ {10}-4 {Hz}) Alfvén waves becomes negative due to acceleration and expansion effects. Medium-frequency ({f}0≈ {10}-3.5 {Hz}) Alfvén waves have a positive growth rate but do not show the signature of PDI up to 1 au because the growth rate is too small. The medium-frequency waves experience neither PDI nor reflection so they propagate through the solar wind most efficiently. The solar wind is shown to possess a frequency-filtering mechanism with respect to Alfvén waves. The simulations with broadband waves indicate that the observed trend of the density fluctuation is well explained by the evolution of PDI while the observed cross-helicity evolution is in agreement with low-frequency wave propagation.

  14. A global wave-driven magnetohydrodynamic solar model with a unified treatment of open and closed magnetic field topologies

    Energy Technology Data Exchange (ETDEWEB)

    Oran, R.; Van der Holst, B.; Landi, E.; Jin, M.; Sokolov, I. V.; Gombosi, T. I., E-mail: oran@umich.edu [Atmospheric, Oceanic and Atmospheric Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI, 48105 (United States)

    2013-12-01

    We describe, analyze, and validate the recently developed Alfvén Wave Solar Model, a three-dimensional global model starting from the top of the chromosphere and extending into interplanetary space (out to 1-2 AU). This model solves the extended, two-temperature magnetohydrodynamics equations coupled to a wave kinetic equation for low-frequency Alfvén waves. In this picture, heating and acceleration of the plasma are due to wave dissipation and to wave pressure gradients, respectively. The dissipation process is described by a fully developed turbulent cascade of counterpropagating waves. We adopt a unified approach for calculating the wave dissipation in both open and closed magnetic field lines, allowing for a self-consistent treatment in any magnetic topology. Wave dissipation is the only heating mechanism assumed in the model; no geometric heating functions are invoked. Electron heat conduction and radiative cooling are also included. We demonstrate that the large-scale, steady state (in the corotating frame) properties of the solar environment are reproduced, using three adjustable parameters: the Poynting flux of chromospheric Alfvén waves, the perpendicular correlation length of the turbulence, and a pseudoreflection coefficient. We compare model results for Carrington rotation 2063 (2007 November-December) with remote observations in the extreme-ultraviolet and X-ray ranges from the Solar Terrestrial Relations Observatory, Solar and Heliospheric Observatory, and Hinode spacecraft and with in situ measurements by Ulysses. The results are in good agreement with observations. This is the first global simulation that is simultaneously consistent with observations of both the thermal structure of the lower corona and the wind structure beyond Earth's orbit.

  15. EFFECTS OF ALFVEN WAVES ON ELECTRON CYCLOTRON MASER EMISSION IN CORONAL LOOPS AND SOLAR TYPE I RADIO STORMS

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, G. Q.; Chen, L.; Wu, D. J. [Purple Mountain Observatory, CAS, Nanjing 210008 (China); Yan, Y. H., E-mail: djwu@pmo.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, CAS, Beijing 100012 (China)

    2013-06-10

    Solar type I radio storms are long-lived radio emissions from the solar atmosphere. It is believed that these type I storms are produced by energetic electrons trapped within a closed magnetic structure and are characterized by a high ordinary (O) mode polarization. However, the microphysical nature of these emissions is still an open problem. Recently, Wu et al. found that Alfven waves (AWs) can significantly influence the basic physics of wave-particle interactions by modifying the resonant condition. Taking the effects of AWs into account, this work investigates electron cyclotron maser emission driven by power-law energetic electrons with a low-energy cutoff distribution, which are trapped in coronal loops by closed solar magnetic fields. The results show that the emission is dominated by the O mode. It is proposed that this O mode emission may possibly be responsible for solar type I radio storms.

  16. SOLAR WAVE-FIELD SIMULATION FOR TESTING PROSPECTS OF HELIOSEISMIC MEASUREMENTS OF DEEP MERIDIONAL FLOWS

    International Nuclear Information System (INIS)

    Hartlep, T.; Zhao, J.; Kosovichev, A. G.; Mansour, N. N.

    2013-01-01

    The meridional flow in the Sun is an axisymmetric flow that is generally directed poleward at the surface, and is presumed to be of fundamental importance in the generation and transport of magnetic fields. Its true shape and strength, however, are debated. We present a numerical simulation of helioseismic wave propagation in the whole solar interior in the presence of a prescribed, stationary, single-cell, deep meridional circulation serving as synthetic data for helioseismic measurement techniques. A deep-focusing time-distance helioseismology technique is applied to the synthetic data, showing that it can in fact be used to measure the effects of the meridional flow very deep in the solar convection zone. It is shown that the ray approximation that is commonly used for interpretation of helioseismology measurements remains a reasonable approximation even for very long distances between 12° and 42° corresponding to depths between 52 and 195 Mm. From the measurement noise, we extrapolate that time-resolved observations on the order of a full solar cycle may be needed to probe the flow all the way to the base of the convection zone.

  17. Solar, wind and waves: Natural limits to renewable sources of energy within the Earth system

    Energy Technology Data Exchange (ETDEWEB)

    Kleidon, Axel [Max-Planck-Institute for Biogeochemistry, Jena (Germany)

    2013-07-01

    Renewable sources of energy, such as solar, wind, wave, or hydropower, utilize energy that is continuously generated by natural processes within the Earth system from the planetary forcing. Here we estimate the limits of these natural energy conversions and the extent to which these can be used as renewable energy sources using the laws of thermodynamics. At most, wind power in the order of 1 000 TW (1 TW = 1E12 W) can be derived from the total flux of incoming solar radiation of 175 000 TW, which is consistent with estimates based on observations. Other generation rates that are derived from the kinetic energy of wind are in the order of 10-100 TW. In comparison, the human primary energy demand of about 17 TW constitutes a considerable fraction of these rates. We provide some further analysis on the limits of wind power using a combination of conceptual models, observational data, and numerical simulation models. We find that many current estimates of wind power substantially overestimate the potential of wind power because the effect of kinetic energy extraction on the air flow is neglected. We conclude that the only form of renewable energy that is available in substantial amounts and that is associated with minor climatic impacts is solar power.

  18. Simulations of short-crested harbour waves with variational Boussinesq modelling

    NARCIS (Netherlands)

    Adytia, D.

    2014-01-01

    Waves propagating from the deep ocean to the coast show large changes in wave height, wave length and direction. The challenge to simulate the essential wave characteristics is in particular to model the speed and nonlinear interaction correctly. All these physical phenomena are present, but hidden,

  19. Dynamics of lumps and dark-dark solitons in the multi-component long-wave-short-wave resonance interaction system

    Science.gov (United States)

    Rao, Jiguang; Porsezian, Kuppuswamy; He, Jingsong; Kanna, Thambithurai

    2018-01-01

    General semi-rational solutions of an integrable multi-component (2+1)-dimensional long-wave-short-wave resonance interaction system comprising multiple short waves and a single long wave are obtained by employing the bilinear method. These solutions describe the interactions between various types of solutions, including line rogue waves, lumps, breathers and dark solitons. We only focus on the dynamical behaviours of the interactions between lumps and dark solitons in this paper. Our detailed study reveals two different types of excitation phenomena: fusion and fission. It is shown that the fundamental (simplest) semi-rational solutions can exhibit fission of a dark soliton into a lump and a dark soliton or fusion of one lump and one dark soliton into a dark soliton. The non-fundamental semi-rational solutions are further classified into three subclasses: higher-order, multi- and mixed-type semi-rational solutions. The higher-order semi-rational solutions show the process of annihilation (production) of two or more lumps into (from) one dark soliton. The multi-semi-rational solutions describe N(N≥2) lumps annihilating into or producing from N-dark solitons. The mixed-type semi-rational solutions are a hybrid of higher-order semi-rational solutions and multi-semi-rational solutions. For the mixed-type semi-rational solutions, we demonstrate an interesting dynamical behaviour that is characterized by partial suppression or creation of lumps from the dark solitons.

  20. Dynamics of lumps and dark-dark solitons in the multi-component long-wave-short-wave resonance interaction system.

    Science.gov (United States)

    Rao, Jiguang; Porsezian, Kuppuswamy; He, Jingsong; Kanna, Thambithurai

    2018-01-01

    General semi-rational solutions of an integrable multi-component (2+1)-dimensional long-wave-short-wave resonance interaction system comprising multiple short waves and a single long wave are obtained by employing the bilinear method. These solutions describe the interactions between various types of solutions, including line rogue waves, lumps, breathers and dark solitons. We only focus on the dynamical behaviours of the interactions between lumps and dark solitons in this paper. Our detailed study reveals two different types of excitation phenomena: fusion and fission. It is shown that the fundamental (simplest) semi-rational solutions can exhibit fission of a dark soliton into a lump and a dark soliton or fusion of one lump and one dark soliton into a dark soliton. The non-fundamental semi-rational solutions are further classified into three subclasses: higher-order, multi- and mixed-type semi-rational solutions. The higher-order semi-rational solutions show the process of annihilation (production) of two or more lumps into (from) one dark soliton. The multi-semi-rational solutions describe N ( N ≥2) lumps annihilating into or producing from N -dark solitons. The mixed-type semi-rational solutions are a hybrid of higher-order semi-rational solutions and multi-semi-rational solutions. For the mixed-type semi-rational solutions, we demonstrate an interesting dynamical behaviour that is characterized by partial suppression or creation of lumps from the dark solitons.

  1. STEREO WAVES Capabilities for Studying Initiation and Early-time Dynamics of Solar Eruptions

    Science.gov (United States)

    Kaiser, M. L.

    2005-01-01

    In 2006, NASA will launch the twin STEREO spacecraft from Kennedy Space Center into a pair of heliocentric orbits near 1 AU such that the spacecraft will move away from Earth (ahead and behind) at about 22 degrees per year. The purposes of the STEREO Mission are to understand the causes and mechanisms of coronal mass ejection (CME) initiation and to follow the propagation of CMEs through the heliosphere. Additionally, STEREO will study the mechanisms and sites of solar energetic particle (SEP) acceleration and determine 3-D time-dependent traces of the magnetic topology, temperature, density and velocity of the solar wind between the sun and Earth. To accomplish these goals, each STEREO spacecraft will be equipped with set of optical and particles and fields instruments including the STEREO WAVES (SWAVES) instrument which will use radio waves to track the location of CME-driven shocks (via type I1 bursts) and the 3-D topology of open field lines along which energetic particles flow (via the ubiquitous type I11 bursts). Type 11 bursts very often commence with a series of special type 111 bursts (called SA or type 111-L bursts) that likely coincide with CME liftoff time, thus SWAVES should be able to determine this time to within 15 sec. It is also known that the occurrence of SEP events is usually accompanied by type I1 radio bursts at decametric wavelengths as well as strong type III bursts at all wavelengths. SWAVES will be able to determine the initiation of these bursts to within 15 sec, and from the simultaneous measurements from the two spacecraft, should be able to triangulate their source locations. The utility of radio observations and the capabilities of SWAVES will be illustrated by showing a number of examples using the similar Wind WAVES instrument in combination with SOH0 coronagraph and RHESSI high energy X-ray/gamma ray observations.

  2. Synthetic spectral analysis of a kinetic model for slow-magnetosonic waves in solar corona

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, Wenzhi; He, Jiansen; Tu, Chuanyi; Wang, Linghua [School of Earth and Space Sciences, Peking University, Beijing, 100871, China, E-mail: jshept@gmail.com (China); Zhang, Lei [State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Vocks, Christian [Leibniz-Institut für Astrophysik Potsdam, 14482, Potsdam (Germany); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, 24118 Kiel (Germany); Peter, Hardi [Max Plank Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen (Germany)

    2016-03-25

    We propose a kinetic model of slow-magnetosonic waves to explain various observational features associated with the propagating intensity disturbances (PIDs) occurring in the solar corona. The characteristics of slow mode waves, e.g, inphase oscillations of density, velocity, and thermal speed, are reproduced in this kinetic model. Moreover, the red-blue (R-B) asymmetry of the velocity distribution as self-consistently generated in the model is found to be contributed from the beam component, as a result of the competition between Landau resonance and Coulomb collisions. Furthermore, we synthesize the spectral lines and make the spectral analysis, based on the kinetic simulation data of the flux tube plasmas and the hypothesis of the surrounding background plasmas. It is found that the fluctuations of parameters of the synthetic spectral lines are basically consistent with the observations: (1) the line intensity, Doppler shift, and line width are fluctuating in phase; (2) the R-B asymmetry usually oscillate out of phase with the former three parameters; (3) the blueward asymmetry is more evident than the redward asymmetry in the R-B fluctuations. The oscillations of line parameters become weakened for the case with denser surrounding background plasmas. Similar to the observations, there is no doubled-frequency oscillation of the line width for the case with flux-tube plasmas flowing bulkly upward among the static background plasmas. Therefore, we suggest that the “wave + beam flow” kinetic model may be a viable interpretation for the PIDs observed in the solar corona.

  3. TURBULENCE IN THE SUB-ALFVENIC SOLAR WIND DRIVEN BY REFLECTION OF LOW-FREQUENCY ALFVEN WAVES

    International Nuclear Information System (INIS)

    Verdini, A.; Velli, M.; Buchlin, E.

    2009-01-01

    We study the formation and evolution of a turbulent spectrum of Alfven waves driven by reflection off the solar wind density gradients, starting from the coronal base up to 17 solar radii, well beyond the Alfvenic critical point. The background solar wind is assigned and two-dimensional shell models are used to describe nonlinear interactions. We find that the turbulent spectra are influenced by the nature of the reflected waves. Close to the base, these give rise to a flatter and steeper spectrum for the outgoing and reflected waves, respectively. At higher heliocentric distance both spectra evolve toward an asymptotic Kolmogorov spectrum. The turbulent dissipation is found to account for at least half of the heating required to sustain the background imposed solar wind and its shape is found to be determined by the reflection-determined turbulent heating below 1.5 solar radii. Therefore, reflection and reflection-driven turbulence are shown to play a key role in the acceleration of the fast solar wind and origin of the turbulent spectrum found at 0.3 AU in the heliosphere.

  4. Magnetic swirls and associated fast magnetoacoustic kink waves in a solar chromospheric flux tube

    Science.gov (United States)

    Murawski, K.; Kayshap, P.; Srivastava, A. K.; Pascoe, D. J.; Jelínek, P.; Kuźma, B.; Fedun, V.

    2018-02-01

    We perform numerical simulations of impulsively generated magnetic swirls in an isolated flux tube that is rooted in the solar photosphere. These swirls are triggered by an initial pulse in a horizontal component of the velocity. The initial pulse is launched either (a) centrally, within the localized magnetic flux tube or (b) off-central, in the ambient medium. The evolution and dynamics of the flux tube are described by three-dimensional, ideal magnetohydrodynamic equations. These equations are numerically solved to reveal that in case (a) dipole-like swirls associated with the fast magnetoacoustic kink and m = 1 Alfvén waves are generated. In case (b), the fast magnetoacoustic kink and m = 0 Alfvén modes are excited. In both these cases, the excited fast magnetoacoustic kink and Alfvén waves consist of a similar flow pattern and magnetic shells are also generated with clockwise and counter-clockwise rotating plasma within them, which can be the proxy of dipole-shaped chromospheric swirls. The complex dynamics of vortices and wave perturbations reveals the channelling of sufficient amount of energy to fulfil energy losses in the chromosphere (˜104 W m-1) and in the corona (˜102 W m-1). Some of these numerical findings are reminiscent of signatures in recent observational data.

  5. Wave-Particle Interactions in the Radiation Belts, Aurora,and Solar Wind: Opportunities for Lab Experiments

    Science.gov (United States)

    Kletzing, C.

    2017-12-01

    The physics of the creation, loss, and transport of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field and particle interactions are involved in this physics from large-scale ring current ion and magnetic field dynamics to microscopic kinetic interactions of whistler-mode chorus waves with energetic electrons. To measure these kinds of radiation belt interactions, NASA implemented the two-satellite Van Allen Probes mission. As part of the mission, the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation is an integrated set of instruments consisting of a triaxial fluxgate magnetometer (MAG) and a Waves instrument which includes a triaxial search coil magnetometer (MSC). We show a variety of waves thought to be important for wave particle interactionsin the radiation belts: low frequency ULF pulsations, EMIC waves, and whistler mode waves including upper and lower band chorus. Outside ofthe radiation belts, Alfven waves play a key role in both solar wind turbulenceand auroral particle acceleration. Several of these wave modes could benefit (or have benefitted) from laboratory studies to further refineour understanding of the detailed physics of the wave-particle interactionswhich lead to energization, pitch angle scattering, and cross-field transportWe illustrate some of the processes and compare the wave data with particle measurements to show relationships between wave activity and particle processobserved in the inner magnetosphere and heliosphere.

  6. Stationary spectra of short-wave convective and magnetostatic fluctuations in a finite-pressure plasma and anomalous heat conductivity

    International Nuclear Information System (INIS)

    Vakulenko, M.O.

    1992-01-01

    Within the general renormalized statistical approach, the low-frequency short-wave stationary spectra of potential and magnetic perturbations in a finite-pressure plasma, are obtained. Anomalous heat conductivity considerably enhances due to non-linear interaction between magnetic excitations. 11 refs. (author)

  7. Capability of simultaneous Rayleigh LiDAR and O2 airglow measurements in exploring the short period wave characteristics

    Science.gov (United States)

    Taori, Alok; Raghunath, Karnam; Jayaraman, Achuthan

    We use combination of simultaneous measurements made with Rayleigh lidar and O2 airglow monitoring to improve lidar investigation capability to cover a higher altitude range. We feed instantaneous O2 airglow temperatures instead the model values at the top altitude for subsequent integration method of temperature retrieval using Rayleigh lidar back scattered signals. Using this method, errors in the lidar temperature estimates converges at higher altitudes indicating better altitude coverage compared to regular methods where model temperatures are used instead of real-time measurements. This improvement enables the measurements of short period waves at upper mesospheric altitudes (~90 km). With two case studies, we show that above 60 km the few short period wave amplitude drastically increases while, some of the short period wave show either damping or saturation. We claim that by using such combined measurements, a significant and cost effective progress can be made in the understanding of short period wave processes which are important for the coupling across the different atmospheric regions.

  8. Short-term effects of a standardized glucose load on region-specific aortic pulse wave velocity assessed by MRI

    NARCIS (Netherlands)

    Jonker, J.T.; Tjeerdema, N.; Hensen, L.C.; Lamb, H.J.; Romijn, J.A.; Smit, J.W.; Westenberg, J.J.; Roos, A. de

    2014-01-01

    PURPOSE: To assess the short-term effects of a standardized oral glucose load on regional aortic pulse wave velocity (PWV) using two-directional in-plane velocity encoded MRI. MATERIALS AND METHODS: A randomized, controlled intervention was performed in 16 male subjects (mean +/- standard deviation:

  9. A novel method for surface defect inspection of optic cable with short-wave infrared illuminance

    Science.gov (United States)

    Chen, Xiaohong; Liu, Ning; You, Bo; Xiao, Bin

    2016-07-01

    Intelligent on-line detection of cable quality is a crucial issue in optic cable factory, and defects on the surface of optic cable can dramatically depress cable grade. Manual inspection in optic cable quality cannot catch up with the development of optic cable industry due to its low detection efficiency and huge human cost. Therefore, real-time is highly demanded by industry in order to replace the subjective and repetitive process of manual inspection. For this reason, automatic cable defect inspection has been a trend. In this paper, a novel method for surface defect inspection of optic cable with short-wave infrared illuminance is presented. The special condition of short-wave infrared cannot only provide illumination compensation for the weak illumination environment, but also can avoid the problem of exposure when using visible light illuminance, which affects the accuracy of inspection algorithm. A series of image processing algorithms are set up to analyze cable image for the verification of real-time and veracity of the detection method. Unlike some existing detection algorithms which concentrate on the characteristics of defects with an active search way, the proposed method removes the non-defective areas of the image passively at the same time of image processing, which reduces a large amount of computation. OTSU algorithm is used to convert the gray image to the binary image. Furthermore, a threshold window is designed to eliminate the fake defects, and the threshold represents the considered minimum size of defects ε . Besides, a new regional suppression method is proposed to deal with the edge burrs of the cable, which shows the superior performance compared with that of Open-Close operation of mathematical morphological in the boundary processing. Experimental results of 10,000 samples show that the rates of miss detection and false detection are 2.35% and 0.78% respectively when ε equals to 0.5 mm, and the average processing period of one frame

  10. Excitation of short-scale fluctuations by parametric decay of helicon waves into ion-sound and Trivelpiece-Gould waves

    International Nuclear Information System (INIS)

    Lorenz, B; Kraemer, M; Selenin, V L; Aliev, Yu M

    2005-01-01

    The helicon wave field and the excitation of short-scale electrostatic fluctuations in a helicon-produced plasma are closely related as both the helicon wave damping and the fluctuation level are shown to increase with the launched rf power. Correlation methods using electrostatic probes as well as microwave back-scattering at the upper-hybrid resonance are applied to obtain the dispersion relations of the fluctuations in the low-frequency and high-frequency ranges. The frequency and wavenumber spectra measured for all components of the wave vector allow us to identify the fluctuations as ion-sound and Trivelpiece-Gould waves that originate from parametric decay of the helicon pump wave. The growth rates and thresholds inferred from the evolution of the fluctuations in a wide range of helicon plasma parameters are in good agreement with predictions for the parametric decay instability that takes into account realistic damping rates for the decay waves as well as non-vanishing parallel wavenumber of the helicon pump

  11. Short-Term Environmental Effects and Their Influence on Spatial Homogeneity of Organic Solar Cell Functionality.

    Science.gov (United States)

    Chien, Huei-Ting; Zach, Peter W; Friedel, Bettina

    2017-08-23

    In this study, we focus on the induced degradation and spatial inhomogeneity of organic photovoltaic devices under different environmental conditions, uncoupled from the influence of any auxiliary hole-transport (HT) layer. During testing of the corresponding devices comprising the standard photoactive layer of poly(3-hexylthiophene) as donor, blended with phenyl-C 61 -butyric acid methyl ester as acceptor, a comparison was made between the nonencapsulated devices upon exposure to argon in the dark, dry air in the dark, dry air with illumination, and humid air in the dark. The impact on the active layer's photophysics is discussed, along with the device physics in terms of integral solar cell performance and spatially resolved photocurrent distribution with point-to-point analysis of the diode characteristics to determine the origin of the observed integrated organic photovoltaic device behavior. The results show that even without the widely used hygroscopic HT layer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), humidity is still a major factor in the short-term environmental degradation of organic solar cells with this architecture, and not only oxygen or light, as is often reported. Different from previous reports where water-induced device degradation was spatially homogeneous and formation of Al 2 O 3 islands was only seen for oxygen permeation through pinholes in aluminum, we observed insulating islands merely after humidity exposure in the present study. Further, we demonstrated with laser beam induced current mapping and point-to-point diode analysis that the water-induced performance losses are a result of the exposed device area comprising regions with entirely unaltered high output and intact diode behavior and those with severe degradation showing detrimentally lowered output and voltage-independent charge blocking, which is essentially insulating behavior. It is suggested that this is caused by transport of water through pinholes to the

  12. Short (

    NARCIS (Netherlands)

    Telleman, Gerdien; den Hartog, Laurens

    2013-01-01

    Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE

  13. Noise characteristics analysis of short wave infrared InGaAs focal plane arrays

    Science.gov (United States)

    Yu, Chunlei; Li, Xue; Yang, Bo; Huang, Songlei; Shao, Xiumei; Zhang, Yaguang; Gong, Haimei

    2017-09-01

    The increasing application of InGaAs short wave infrared (SWIR) focal plane arrays (FPAs) in low light level imaging requires ultra-low noise FPAs. This paper presents the theoretical analysis of FPA noise, and point out that both dark current and detector capacitance strongly affect the FPA noise. The impact of dark current and detector capacitance on FPA noise is compared in different situations. In order to obtain low noise performance FPAs, the demand for reducing detector capacitance is higher especially when pixel pitch is smaller, integration time is shorter, and integration capacitance is larger. Several InGaAs FPAs were measured and analyzed, the experiments' results could be well fitted to the calculated results. The study found that the major contributor of FPA noise is coupled noise with shorter integration time. The influence of detector capacitance on FPA noise is more significant than that of dark current. To investigate the effect of detector performance on FPA noise, two kinds of photodiodes with different concentration of the absorption layer were fabricated. The detectors' performance and noise characteristics were measured and analyzed, the results are consistent with that of theoretical analysis.

  14. Short-distance behavior of the Bethe--Salpeter wave function in the ladder approximation

    International Nuclear Information System (INIS)

    Guth, A.H.; Soper, D.E.

    1975-01-01

    We investigate the short-distance behavior of the (Wick-rotated) Bethe--Salpeter wave function for the two spin-1/2 quarks bound by the exchange of a massive vector meson. We use the ladder-model kernel, which has the same p -4 scaling behavior as the true kernel in a theory with a fixed point of the renormalization group at g not equal to 0. For a bound state with the quantum numbers of the pion, the leading asymptotic behavior is chi (q/sup μ/) approx. cq/sup -4 + epsilon(g)/γ 5 , where epsilon (g) =1- (1-g 2 /π 2 ) 1 / 2 . Our method also provides the full asymptotic series, although it should be noted that the nonleading terms will depend on the nonleading behavior of the ladder-model kernel. A general term has the form cq - /sup a/(lnq)/sup n/phi (q/sup μ/), where c is an unknown constant, a may be integral or nonintegral, n is an integer, and phi (q/sup μ/) is a representation function of the rotation group in four dimensions

  15. Exploring short-GRB afterglow parameter space for observations in coincidence with gravitational waves

    Science.gov (United States)

    Saleem, M.; Resmi, L.; Misra, Kuntal; Pai, Archana; Arun, K. G.

    2018-03-01

    Short duration Gamma Ray Bursts (SGRB) and their afterglows are among the most promising electromagnetic (EM) counterparts of Neutron Star (NS) mergers. The afterglow emission is broad-band, visible across the entire electromagnetic window from γ-ray to radio frequencies. The flux evolution in these frequencies is sensitive to the multidimensional afterglow physical parameter space. Observations of gravitational wave (GW) from BNS mergers in spatial and temporal coincidence with SGRB and associated afterglows can provide valuable constraints on afterglow physics. We run simulations of GW-detected BNS events and assuming that all of them are associated with a GRB jet which also produces an afterglow, investigate how detections or non-detections in X-ray, optical and radio frequencies can be influenced by the parameter space. We narrow down the regions of afterglow parameter space for a uniform top-hat jet model, which would result in different detection scenarios. We list inferences which can be drawn on the physics of GRB afterglows from multimessenger astronomy with coincident GW-EM observations.

  16. Magnetar Central Engine and Possible Gravitational Wave Emission of Nearby Short GRB 160821B

    Energy Technology Data Exchange (ETDEWEB)

    Lü, Hou-Jun; Zhang, Hai-Ming; Zhong, Shu-Qing; Liang, En-Wei [GXU-NAOC Center for Astrophysics and Space Sciences, Department of Physics, Guangxi University, Nanning 530004 (China); Hou, Shu-Jin [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang, Henan 473061 (China); Sun, Hui [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Rice, Jared, E-mail: lhj@gxu.edu.edu [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States)

    2017-02-01

    GRB 160821B is a short gamma-ray burst (SGRB) at redshift z = 0.16, with a duration less than 1 s and without any “extended emission” detected up to more than 100 s in both Swift /BAT and Fermi /GBM bands. An X-ray plateau with a sharp drop 180 s after the BAT trigger was observed with Swift /XRT. No supernova or kilo-nova signature was detected. Assuming the central engine of this SGRB is a recently born supra-massive magnetar, we can explain the SGRB as jet radiation and its X-ray plateau as the internal energy dissipation of the pulsar wind as it spins down. We constrain its surface magnetic field to B {sub p} < 3.12 × 10{sup 16} G and initial spin period to P{sub 0} < 8.5 × 10{sup −3} s. Its equation of state is consistent with the GM1 model with M{sub TOV} ∼ 2.37 M {sub ⊙} and ellipticity ϵ < 0.07. Its gravitational wave (GW) radiation may be detectable with the future Einstein Telescope, but is much weaker than the current detectability limit of Advanced LIGO. The GW radiation of such an event would be detectable by Advanced LIGO if it occurred at a distance of 100 Mpc ( z = 0.023).

  17. Short-Wave Near-Infrared Spectrometer for Alcohol Determination and Temperature Correction

    Directory of Open Access Journals (Sweden)

    Qingbo Fu

    2012-01-01

    Full Text Available A multichannel short-wave near-infrared (SW-NIR spectrometer module based on charge-coupled device (CCD detection was designed. The design relied on a tungsten lamp enhanced by light emitting diodes, a fixed grating monochromator and a linear CCD array. The main advantages were high optical resolution and an optimized signal-to-noise ratio (0.24 nm and 500, resp. in the whole wavelength range of 650 to 1100 nm. An application to alcohol determination using partial least squares calibration and the temperature correction was presented. It was found that the direct transfer method had significant systematic prediction errors due to temperature effect. Generalized least squares weighting (GLSW method was utilized for temperature correction. After recalibration, the RMSEP found for the 25°C model was 0.53% v/v and errors of the same order of magnitude were obtained at other temperatures (15, 35 and 40°C. And an 2 better than 0.99 was achieved for each validation set. The possibility and accuracy of using the miniature SW-NIR spectrometer and GLSW transfer calibration method for alcohol determination at different temperatures were proven. And the analysis procedure was simple and fast, allowing a strict control of alcohol content in the wine industry.

  18. CORONAL HEATING BY SURFACE ALFVEN WAVE DAMPING: IMPLEMENTATION IN A GLOBAL MAGNETOHYDRODYNAMICS MODEL OF THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Evans, R. M. [NASA Goddard Space Flight Center, Space Weather Lab, Greenbelt, MD 20771 (United States); Opher, M. [Astronomy Department, Boston University, 675 Commonwealth Avenue, Boston, MA 02215 (United States); Oran, R.; Van der Holst, B.; Sokolov, I. V.; Frazin, R.; Gombosi, T. I. [Center for Space Environment Modeling, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); Vasquez, A., E-mail: Rebekah.e.frolov@nasa.gov [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA) and FCEN (UBA), CC 67, Suc 28, Ciudad de Buenos Aires (Argentina)

    2012-09-10

    The heating and acceleration of the solar wind is an active area of research. Alfven waves, because of their ability to accelerate and heat the plasma, are a likely candidate in both processes. Many models have explored wave dissipation mechanisms which act either in closed or open magnetic field regions. In this work, we emphasize the boundary between these regions, drawing on observations which indicate unique heating is present there. We utilize a new solar corona component of the Space Weather Modeling Framework, in which Alfven wave energy transport is self-consistently coupled to the magnetohydrodynamic equations. In this solar wind model, the wave pressure gradient accelerates and wave dissipation heats the plasma. Kolmogorov-like wave dissipation as expressed by Hollweg along open magnetic field lines was presented in van der Holst et al. Here, we introduce an additional dissipation mechanism: surface Alfven wave (SAW) damping, which occurs in regions with transverse (with respect to the magnetic field) gradients in the local Alfven speed. For solar minimum conditions, we find that SAW dissipation is weak in the polar regions (where Hollweg dissipation is strong), and strong in subpolar latitudes and the boundaries of open and closed magnetic fields (where Hollweg dissipation is weak). We show that SAW damping reproduces regions of enhanced temperature at the boundaries of open and closed magnetic fields seen in tomographic reconstructions in the low corona. Also, we argue that Ulysses data in the heliosphere show enhanced temperatures at the boundaries of fast and slow solar wind, which is reproduced by SAW dissipation. Therefore, the model's temperature distribution shows best agreement with these observations when both dissipation mechanisms are considered. Lastly, we use observational constraints of shock formation in the low corona to assess the Alfven speed profile in the model. We find that, compared to a polytropic solar wind model, the wave

  19. Kink Waves in Non-isothermal Stratified Solar Waveguides: Effect of the External Magnetic Field

    Energy Technology Data Exchange (ETDEWEB)

    Lopin, I. [Ussuriisk Astrophysical Observatory, Russian Academy of Sciences (Russian Federation); Nagorny, I., E-mail: lopin78@mail.ru [Institute of Automation and Control Processes FEB RAS, Vladivostok (Russian Federation)

    2017-10-01

    We study the effect of an external magnetic field on the properties of kink waves, propagating along a thin non-isothermal stratified and diverging magnetic flux tube. A wave equation, governing the propagation of kink waves under the adopted model is derived. It is shown that the vertical gradient of temperature introduces a spatially local cut-off frequency ω {sub c}. The vertical distribution of the cut-off frequency is calculated for the reference VAL-C model of the solar atmosphere and for different values of a ratio of external to internal magnetic fields. The results show that the cut-off frequency is negative below the temperature minimum due to the negative temperature gradient. In the chromosphere the cut-off frequency at a given height is smaller for a stronger external magnetic field. For the appropriate range of a ratio B{sub e} / B{sub i}  ≈ 0–0.8, the cutoff lies in the range ω{sub c}  ≈ 0.003–0.010 s{sup −1} (periods 600 < P{sub c} < 2000 s). The estimate of the cut-off frequency in the transition region is provided as well. In the propagating wave regime, the effective wave energy flux in the non-isothermal diverging flux tubes is the same as in the straight and homogeneous cylindrical waveguides. The obtained wave equation in the limit β  = 0 is used to study the kink oscillations of non-isothermal coronal loops. It is found that the gradient of temperature along the coronal loops reduces the frequency ratio of the first overtone to the fundamental mode, i.e., ω{sub 2}/ ω{sub 1} < 2. This reduction grows for a larger ratio of temperature at the loop top to the temperature at the footpoints. Moreover, the effect of reduction is most pronounced for the steeper temperature profiles.

  20. Properties of a Small-scale Short-duration Solar Eruption with a Driven Shock

    Science.gov (United States)

    Ying, Beili; Feng, Li; Lu, Lei; Zhang, Jie; Magdalenic, Jasmina; Su, Yingna; Su, Yang; Gan, Weiqun

    2018-03-01

    Large-scale solar eruptions have been extensively explored over many years. However, the properties of small-scale events with associated shocks have rarely been investigated. We present analyses of a small-scale, short-duration event originating from a small region. The impulsive phase of the M1.9-class flare lasted only four minutes. The kinematic evolution of the CME hot channel reveals some exceptional characteristics, including a very short duration of the main acceleration phase (fast and impulsive kinematics subsequently results in a piston-driven shock related to a metric type II radio burst with a high starting frequency of ∼320 MHz of the fundamental band. The type II source is formed at a low height of below 1.1 R ⊙ less than ∼2 minutes after the onset of the main acceleration phase. Through the band-split of the type II burst, the shock compression ratio decreases from 2.2 to 1.3, and the magnetic field strength of the shock upstream region decreases from 13 to 0.5 Gauss at heights of 1.1–2.3 R ⊙. We find that the CME (∼4 × 1030 erg) and flare (∼1.6 × 1030 erg) consume similar amounts of magnetic energy. The same conclusion for large-scale eruptions implies that small- and large-scale events possibly share a similar relationship between CMEs and flares. The kinematic particularities of this event are possibly related to the small footpoint-separation distance of the associated magnetic flux rope, as predicted by the Erupting Flux Rope model.

  1. Study of s-component of the solar radio emission and short-term quantitative prediction of powerful solar flares

    International Nuclear Information System (INIS)

    Guseynov, Sh; Gakhramanov, I.G.

    2012-01-01

    Full text : All living and non-living things on Earth is dependent on the processes occurring in the Sun. Therefore the study of the Sun with the aim to predict powerful solar flares is of great scientific and practical importance. It is known that the main drawback of modern forecasting of solar flares and the low reliability of forecasts is the lack of use of the physical concepts of the mechanism of flares

  2. A simulation model for the actual, long wave and net solar radiation computing

    International Nuclear Information System (INIS)

    Kolev, B.; Stoilov, A.; Lyubomirov, L.

    2004-01-01

    The main purpose of this study is to present a calculating procedure for the components of the radiation balance - actual, long-wave and net radiation calculation, using the sunshine duration and the standard meteorological information, through a previously prepared program product.To calculate the actual solar radiation using the total cloudiness only, an empirical regression model has been developed. The results of the coefficient of correlation R(0.75-0.88), respectively for the spring and summer periods (March-May; June-August) show the adequacy of the chosen model. The verification of the model on the independent experimental material prove that the approach that authors suggested, can be successfully applied to the calculation of the actual radiation of the current place

  3. An operational integrated short-term warning solution for solar radiation storms: introducing the Forecasting Solar Particle Events and Flares (FORSPEF) system

    Science.gov (United States)

    Anastasiadis, Anastasios; Sandberg, Ingmar; Papaioannou, Athanasios; Georgoulis, Manolis; Tziotziou, Kostas; Jiggens, Piers; Hilgers, Alain

    2015-04-01

    We present a novel integrated prediction system, of both solar flares and solar energetic particle (SEP) events, which is in place to provide short-term warnings for hazardous solar radiation storms. FORSPEF system provides forecasting of solar eruptive events, such as solar flares with a projection to coronal mass ejections (CMEs) (occurrence and velocity) and the likelihood of occurrence of a SEP event. It also provides nowcasting of SEP events based on actual solar flare and CME near real-time alerts, as well as SEP characteristics (peak flux, fluence, rise time, duration) per parent solar event. The prediction of solar flares relies on a morphological method which is based on the sophisticated derivation of the effective connected magnetic field strength (Beff) of potentially flaring active-region (AR) magnetic configurations and it utilizes analysis of a large number of AR magnetograms. For the prediction of SEP events a new reductive statistical method has been implemented based on a newly constructed database of solar flares, CMEs and SEP events that covers a large time span from 1984-2013. The method is based on flare location (longitude), flare size (maximum soft X-ray intensity), and the occurrence (or not) of a CME. Warnings are issued for all > C1.0 soft X-ray flares. The warning time in the forecasting scheme extends to 24 hours with a refresh rate of 3 hours while the respective warning time for the nowcasting scheme depends on the availability of the near real-time data and falls between 15-20 minutes. We discuss the modules of the FORSPEF system, their interconnection and the operational set up. The dual approach in the development of FORPSEF (i.e. forecasting and nowcasting scheme) permits the refinement of predictions upon the availability of new data that characterize changes on the Sun and the interplanetary space, while the combined usage of solar flare and SEP forecasting methods upgrades FORSPEF to an integrated forecasting solution. This

  4. High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

    2017-06-27

    Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm 2 active area and 18% over a 1 cm 2 active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

  5. THE BEHAVIOR OF TRANSVERSE WAVES IN NONUNIFORM SOLAR FLUX TUBES. I. COMPARISON OF IDEAL AND RESISTIVE RESULTS

    International Nuclear Information System (INIS)

    Soler, Roberto; Terradas, Jaume; Oliver, Ramón; Goossens, Marcel

    2013-01-01

    Magnetohydrodynamic (MHD) waves are ubiquitously observed in the solar atmosphere. Kink waves are a type of transverse MHD waves in magnetic flux tubes that are damped due to resonant absorption. The theoretical study of kink MHD waves in solar flux tubes is usually based on the simplification that the transverse variation of density is confined to a nonuniform layer much thinner than the radius of the tube, i.e., the so-called thin boundary approximation. Here, we develop a general analytic method to compute the dispersion relation and the eigenfunctions of ideal MHD waves in pressureless flux tubes with transversely nonuniform layers of arbitrary thickness. Results for kink waves are produced and compared with fully numerical resistive MHD eigenvalue computations in the limit of small resistivity. We find that the frequency and resonant damping rate are the same in both ideal and resistive cases. The actual results for thick nonuniform layers deviate from the behavior predicted in the thin boundary approximation and strongly depend on the shape of the nonuniform layer. The eigenfunctions in ideal MHD are very different from those in resistive MHD. The ideal eigenfunctions display a global character regardless of the thickness of the nonuniform layer, while the resistive eigenfunctions are localized around the resonance and are indistinguishable from those of ordinary resistive Alfvén modes. Consequently, the spatial distribution of wave energy in the ideal and resistive cases is dramatically different. This poses a fundamental theoretical problem with clear observational consequences

  6. Role of Interaction between Magnetic Rossby Waves and Tachocline Differential Rotation in Producing Solar Seasons

    Science.gov (United States)

    Dikpati, Mausumi; McIntosh, Scott W.; Bothun, Gregory; Cally, Paul S.; Ghosh, Siddhartha S.; Gilman, Peter A.; Umurhan, Orkan M.

    2018-02-01

    We present a nonlinear magnetohydrodynamic shallow-water model for the solar tachocline (MHD-SWT) that generates quasi-periodic tachocline nonlinear oscillations (TNOs) that can be identified with the recently discovered solar “seasons.” We discuss the properties of the hydrodynamic and magnetohydrodynamic Rossby waves that interact with the differential rotation and toroidal fields to sustain these oscillations, which occur due to back-and-forth energy exchanges among potential, kinetic, and magnetic energies. We perform model simulations for a few years, for selected example cases, in both hydrodynamic and magnetohydrodynamic regimes and show that the TNOs are robust features of the MHD-SWT model, occurring with periods of 2–20 months. We find that in certain cases multiple unstable shallow-water modes govern the dynamics, and TNO periods vary with time. In hydrodynamically governed TNOs, the energy exchange mechanism is simple, occurring between the Rossby waves and differential rotation. But in MHD cases, energy exchange becomes much more complex, involving energy flow among six energy reservoirs by means of eight different energy conversion processes. For toroidal magnetic bands of 5 and 35 kG peak amplitudes, both placed at 45° latitude and oppositely directed in north and south hemispheres, we show that the energy transfers responsible for TNO, as well as westward phase propagation, are evident in synoptic maps of the flow, magnetic field, and tachocline top-surface deformations. Nonlinear mode–mode interaction is particularly dramatic in the strong-field case. We also find that the TNO period increases with a decrease in rotation rate, implying that the younger Sun had more frequent seasons.

  7. Propagation of short-period gravity waves at high-latitudes during the MaCWAVE winter campaign

    Directory of Open Access Journals (Sweden)

    K. Nielsen

    2006-07-01

    Full Text Available As part of the MaCWAVE (Mountain and Convective Waves Ascending Vertically winter campaign an all-sky monochromatic CCD imager has been used to investigate the properties of short-period mesospheric gravity waves at high northern latitudes. Sequential measurements of several nightglow emissions were made from Esrange, Sweden, during a limited period from 27–31 January 2003. Coincident wind measurements over the altitude range (~80–100 km using two meteor radar systems located at Esrange and Andenes have been used to perform a novel investigation of the intrinsic properties of five distinct wave events observed during this period. Additional lidar and MSIS model temperature data have been used to investigate their nature (i.e. freely propagating or ducted. Four of these extensive wave events were found to be freely propagating with potential source regions to the north of Scandinavia. No evidence was found for strong orographic forcing by short-period waves in the airglow emission layers. The fifth event was most unusual exhibiting an extensive, but much smaller and variable wavelength pattern that appeared to be embedded in the background wind field. Coincident wind measurements indicated the presence of a strong shear suggesting this event was probably due to a large-scale Kelvin-Helmholtz instability.

  8. Implications of Wide-Area Geographic Diversity for Short- Term Variability of Solar Power

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Andrew; Wiser, Ryan

    2010-08-23

    Worldwide interest in the deployment of photovoltaic generation (PV) is rapidly increasing. Operating experience with large PV plants, however, demonstrates that large, rapid changes in the output of PV plants are possible. Early studies of PV grid impacts suggested that short-term variability could be a potential limiting factor in deploying PV. Many of these early studies, however, lacked high-quality data from multiple sites to assess the costs and impacts of increasing PV penetration. As is well known for wind, accounting for the potential for geographic diversity can significantly reduce the magnitude of extreme changes in aggregated PV output, the resources required to accommodate that variability, and the potential costs of managing variability. We use measured 1-min solar insolation for 23 time-synchronized sites in the Southern Great Plains network of the Atmospheric Radiation Measurement program and wind speed data from 10 sites in the same network to characterize the variability of PV with different degrees of geographic diversity and to compare the variability of PV to the variability of similarly sited wind. The relative aggregate variability of PV plants sited in a dense 10 x 10 array with 20 km spacing is six times less than the variability of a single site for variability on time scales less than 15-min. We find in our analysis of wind and PV plants similarly sited in a 5 x 5 grid with 50 km spacing that the variability of PV is only slightly more than the variability of wind on time scales of 5-15 min. Over shorter and longer time scales the level of variability is nearly identical. Finally, we use a simple approximation method to estimate the cost of carrying additional reserves to manage sub-hourly variability. We conclude that the costs of managing the short-term variability of PV are dramatically reduced by geographic diversity and are not substantially different from the costs for managing the short-term variability of similarly sited wind in

  9. The heating and acceleration actions of the solar plasma wave by QFT

    Science.gov (United States)

    Chen, Shao-Guang

    solar plasma will left-right separate by Lorentz force and by the feedback mechanism of Lorentz force the positive - negative charge will left-right vibrate. The plasma on the move will accompany with up-down and left-right vibrating and become the wave. Though the frequent of the plasma wave is not high, but its heating and acceleration actions will be not less then that of the microwave and laser because of its mass and energy far large then that of the microwave and laser.

  10. Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications

    International Nuclear Information System (INIS)

    Fertig, Fabian; Greulich, Johannes; Rein, Stefan

    2014-01-01

    Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current

  11. Identification of the propagation mode of a solar wind wave associated with Pc5 pulsations in the magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Walker, A.D.M.; Stephenson, J.A.E. [KwaZulu-Natal Univ., Durban (South Africa). School of Chemistry and Physics

    2014-07-01

    A case study of a magnetohydrodynamic (MHD) wave in the solar wind that is strongly correlated with a magnetospheric field line resonance observed by the SuperDARN (Super Dual Auroral Radar Network) radar at Sanae, Antarctica is presented. The data from the ACE (Advanced Composition Explorer) satellite at the solar libration point are analysed. The data time series are bandpass filtered at the pulsation frequency and the analytic signal deduced. From these data the partition of energy between the field components is computed. It is shown that energy is equally partitioned between the kinetic energy and transverse magnetic potential energy densities. The energy flux vector is closely aligned with the background magnetic field. The transverse magnetic and velocity components are in antiphase. This is the first identification of the triggering wave as a transverse Alfven wave which originates upstream from the space craft and is propagated to the magnetosphere to trigger the pulsation.

  12. A Short Progress Report on High-Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Tang, He; He, Shengsheng; Peng, Chuangwei

    2017-12-01

    Faced with the increasingly serious energy and environmental crisis in the world nowadays, the development of renewable energy has attracted increasingly more attention of all countries. Solar energy as an abundant and cheap energy is one of the most promising renewable energy sources. While high-performance solar cells have been well developed in the last couple of decades, the high module cost largely hinders wide deployment of photovoltaic devices. In the last 10 years, this urgent demand for cost-effective solar cells greatly facilitates the research of solar cells. This paper reviews the recent development of cost-effective and high-efficient solar cell technologies. This report paper covers low-cost and high-efficiency perovskite solar cells. The development and the state-of-the-art results of perovskite solar cell technologies are also introduced.

  13. Application of short-wave infrared (SWIR) spectroscopy in quantitative estimation of clay mineral contents

    International Nuclear Information System (INIS)

    You, Jinfeng; Xing, Lixin; Pan, Jun; Meng, Tao; Liang, Liheng

    2014-01-01

    Clay minerals are significant constituents of soil which are necessary for life. This paper studied three types of clay minerals, kaolinite, illite, and montmorillonite, for they are not only the most common soil forming materials, but also important indicators of soil expansion and shrinkage potential. These clay minerals showed diagnostic absorption bands resulting from vibrations of hydroxyl groups and structural water molecules in the SWIR wavelength region. The short-wave infrared reflectance spectra of the soil was obtained from a Portable Near Infrared Spectrometer (PNIS, spectrum range: 1300∼2500 nm, interval: 2 nm). Due to the simplicity, quickness, and the non-destructiveness analysis, SWIR spectroscopy has been widely used in geological prospecting, chemical engineering and many other fields. The aim of this study was to use multiple linear regression (MLR) and partial least squares (PLS) regression to establish the optimizing quantitative estimation models of the kaolinite, illite and montmorillonite contents from soil reflectance spectra. Here, the soil reflectance spectra mainly refers to the spectral reflectivity of soil (SRS) corresponding to the absorption-band position (AP) of kaolinite, illite, and montmorillonite representative spectra from USGS spectral library, the SRS corresponding to the AP of soil spectral and soil overall spectrum reflectance values. The optimal estimation models of three kinds of clay mineral contents showed that the retrieval accuracy was satisfactory (Kaolinite content: a Root Mean Square Error of Calibration (RMSEC) of 1.671 with a coefficient of determination (R 2 ) of 0.791; Illite content: a RMSEC of 1.126 with a R 2 of 0.616; Montmorillonite content: a RMSEC of 1.814 with a R 2 of 0.707). Thus, the reflectance spectra of soil obtained form PNIS could be used for quantitative estimation of kaolinite, illite and montmorillonite contents in soil

  14. Mineral Mapping Using Simulated Worldview-3 Short-Wave-Infrared Imagery

    Directory of Open Access Journals (Sweden)

    Sandra L. Perry

    2013-05-01

    Full Text Available WorldView commercial imaging satellites comprise a constellation developed by DigitalGlobe Inc. (Longmont, CO, USA. Worldview-3 (WV-3, currently planned for launch in 2014, will have 8 spectral bands in the Visible and Near-Infrared (VNIR, and an additional 8 bands in the Short-Wave-Infrared (SWIR; the approximately 1.0–2.5 μm spectral range. WV-3 will be the first commercial system with both high spatial resolution and multispectral SWIR capability. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS data collected at 3 m spatial resolution with 86 SWIR bands having 10 nm spectral resolution were used to simulate the new WV-3 SWIR data. AVIRIS data were converted to reflectance, geographically registered, and resized to the proposed 3.7 and 7.5 m spatial resolutions. WV-3 SWIR band pass functions were used to spectrally resample the data to the proposed 8 SWIR bands. Characteristic reflectance signatures extracted from the data for known mineral locations (endmembers were used to map spatial locations of specific minerals. The WV-3 results, when compared to spectral mapping using the full AVIRIS SWIR dataset, illustrate that the WV-3 spectral bands should permit identification and mapping of some key minerals, however, minerals with similar spectral features may be confused and will not be mapped with the same detail as using hyperspectral systems. The high spatial resolution should provide detailed mapping of complex alteration mineral patterns not achievable by current multispectral systems. The WV-3 simulation results are promising and indicate that this sensor will be a significant tool for geologic remote sensing.

  15. Stabilized platform for tethered balloon soundings of broadband long- and short-wave radiation

    International Nuclear Information System (INIS)

    Alzheimer, J.M.; Anderson, G.A.; Whiteman, C.D.

    1993-01-01

    Changes in the composition of trace gases in the earth's atmosphere have been reported by many observers, and a general concern has been expressed regarding possible changes to the earth's climate that may be caused by radiatively active gases introduced into the earth's atmosphere by man's activities. Radiatively active trace gases produce temperature changes in the earth's atmosphere through changes in radiative flux divergence. Our knowledge of and means of measuring radiative flux divergence is very limited. A few observations of vertical radiative flux divergences have been reported from aircraft from radiometersondes from towers and from large tethered balloons. These measurement techniques suffers from one or more drawbacks, including shallow sounding depths (towers), high cost (aircraft), complicated logistics (large tethered balloons), and limitation to nighttime hours (radiometersondes). Changes in radiative flux divergence caused by anthropogenic trace gases are expected to be quite small, and will be difficult to measure with existing broadband radiative flux instruments. The emphasis of present research in global climate change is thus being focused on improving radiative transfer algorithms in global climate models. The radiative parameterizations in these models are at an early stage of development and information is needed regarding their performance, especially in cloudy conditions. The impetus for the research reported in this paper is the need for a device that can supplement existing means of measuring vertical profiles of long- and short-wave irradiance and radiative flux divergence. We have designed a small tethered-balloon-based system that can make radiometric soundings through the atmospheric boundary layer. This paper discusses the concept, the design considerations, and the design and construction of this sounding system. The performance of the system will be tested in a series of balloon flights scheduled for the fall and winter of 1992

  16. Phase Inversion: Inferring Solar Subphotospheric Flow and Other Asphericity from the Distortion of Acoustic Waves

    Science.gov (United States)

    Gough, Douglas; Merryfield, William J.; Toomre, Juri

    1998-01-01

    A method is proposed for analyzing an almost monochromatic train of waves propagating in a single direction in an inhomogeneous medium that is not otherwise changing in time. An effective phase is defined in terms of the Hilbert transform of the wave function, which is related, via the JWKB approximation, to the spatial variation of the background state against which the wave is propagating. The contaminating effect of interference between the truly monochromatic components of the train is eliminated using its propagation properties. Measurement errors, provided they are uncorrelated, are manifest as rapidly varying noise; although that noise can dominate the raw phase-processed signal, it can largely be removed by low-pass filtering. The intended purpose of the analysis is to determine the distortion of solar oscillations induced by horizontal structural variation and material flow. It should be possible to apply the method directly to sectoral modes. The horizontal phase distortion provides a measure of longitudinally averaged properties of the Sun in the vicinity of the equator, averaged also in radius down to the depth to which the modes penetrate. By combining such averages from different modes, the two-dimensional variation can be inferred by standard inversion techniques. After taking due account of horizontal refraction, it should be possible to apply the technique also to locally sectoral modes that propagate obliquely to the equator and thereby build a network of lateral averages at each radius, from which the full three-dimensional structure of the Sun can, in principle, be determined as an inverse Radon transform.

  17. Observation of quasi-periodic solar radio bursts associated with propagating fast-mode waves

    Science.gov (United States)

    Goddard, C. R.; Nisticò, G.; Nakariakov, V. M.; Zimovets, I. V.; White, S. M.

    2016-10-01

    Aims: Radio emission observations from the Learmonth and Bruny Island radio spectrographs are analysed to determine the nature of a train of discrete, periodic radio "sparks" (finite-bandwidth, short-duration isolated radio features) which precede a type II burst. We analyse extreme ultraviolet (EUV) imaging from SDO/AIA at multiple wavelengths and identify a series of quasi-periodic rapidly-propagating enhancements, which we interpret as a fast wave train, and link these to the detected radio features. Methods: The speeds and positions of the periodic rapidly propagating fast waves and the coronal mass ejection (CME) were recorded using running-difference images and time-distance analysis. From the frequency of the radio sparks the local electron density at the emission location was estimated for each. Using an empirical model for the scaling of density in the corona, the calculated electron density was used to obtain the height above the surface at which the emission occurs, and the propagation velocity of the emission location. Results: The period of the radio sparks, δtr = 1.78 ± 0.04 min, matches the period of the fast wave train observed at 171 Å, δtEUV = 1.7 ± 0.2 min. The inferred speed of the emission location of the radio sparks, 630 km s-1, is comparable to the measured speed of the CME leading edge, 500 km s-1, and the speeds derived from the drifting of the type II lanes. The calculated height of the radio emission (obtained from the density) matches the observed location of the CME leading edge. From the above evidence we propose that the radio sparks are caused by the quasi-periodic fast waves, and the emission is generated as they catch up and interact with the leading edge of the CME. The movie associated to Fig. 2 is available at http://www.aanda.org

  18. Short- and medium-term atmospheric constituent effects of very large solar proton events

    Directory of Open Access Journals (Sweden)

    C. H. Jackman

    2008-02-01

    Full Text Available Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude. We have used the Whole Atmosphere Community Climate Model (WACCM3 to study the atmospheric impact of SPEs over the period 1963–2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short- and medium-term (days to a few months atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October–November 2003 as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NOx (NO+NO2 increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO3, N2O5, ClONO2, HOCl, and ClO were indirectly caused by the very large SPEs in October–November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO3 and ClONO2 enhancements being smaller than measured and N2O5 enhancements being larger than measured. The HOCl enhancements were fairly similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric

  19. Short-period atmospheric gravity waves - A study of their statistical properties and source mechanisms

    Science.gov (United States)

    Gedzelman, S. D.

    1983-01-01

    Gravity waves for the one year period beginning 19 October 1976 around Palisades, New York, are investigated to determine their statistical properties and sources. The waves have typical periods of 10 min, pressure amplitudes of 3 Pa and velocities of 30 m/s. In general, the largest, amplitude waves occur during late fall and early winter when the upper tropospheric winds directly overhead are fastest and the static stability of the lower troposphere is greatest. Mean wave amplitudes correlate highly with the product of the mean maximum wind speed and the mean low level stratification directly aloft. A distinct diurnal variation of wave amplitudes with the largest waves occurring in the pre-dawn hours is also observed as a result of the increased static stability then. The majority of waves are generated by shear instability; however, a number of waves are generated by distant sources such as nuclear detonations or large thunderstorms. The waves with distant sources can be distinguished on the basis of their generally much higher coherency across the grid and velocities that depart markedly from the wind velocity at any point in the sounding.

  20. Propagating wave in active region-loops, located over the solar disk observed by the Interface Region Imaging Spectrograph

    Science.gov (United States)

    Zhang, B.; Hou, Y. J.; Zhang, J.

    2018-03-01

    Aims: We aim to ascertain the physical parameters of a propagating wave over the solar disk detected by the Interface Region Imaging Spectrograph (IRIS). Methods: Using imaging data from the IRIS and the Solar Dynamic Observatory (SDO), we tracked bright spots to determine the parameters of a propagating transverse wave in active region (AR) loops triggered by activation of a filament. Deriving the Doppler velocity of Si IV line from spectral observations of IRIS, we have determined the rotating directions of active region loops which are relevant to the wave. Results: On 2015 December 19, a filament was located on the polarity inversion line of the NOAA AR 12470. The filament was activated and then caused a C1.1 two-ribbon flare. Between the flare ribbons, two rotation motions of a set of bright loops were observed to appear in turn with opposite directions. Following the end of the second rotation, a propagating wave and an associated transverse oscillation were detected in these bright loops. In 1400 Å channel, there was bright material flowing along the loops in a wave-like manner, with a period of 128 s and a mean amplitude of 880 km. For the transverse oscillation, we tracked a given loop and determine the transverse positions of the tracking loop in a limited longitudinal range. In both of 1400 Å and 171 Å channels, approximately four periods are distinguished during the transverse oscillation. The mean period of the oscillation is estimated as 143 s and the displacement amplitude as between 1370 km and 690 km. We interpret these oscillations as a propagating kink wave and obtain its speed of 1400 km s-1. Conclusions: Our observations reveal that a flare associated with filament activation could trigger a kink propagating wave in active region loops over the solar disk. Movies associated to Figs. 1-4 are available at http://https://www.aanda.org

  1. Extra-high short-circuit current for bifacial solar cells in sunny and dark-light conditions.

    Science.gov (United States)

    Duan, Jialong; Duan, Yanyan; Zhao, Yuanyuan; He, Benlin; Tang, Qunwei

    2017-09-05

    We present here a symmetrically structured bifacial solar cell tailored by two fluorescent photoanodes and a platinum/titanium/platinum counter electrode, yielding extra-high short-circuit current densities as high as 28.59 mA cm -2 and 119.9 μA cm -2 in simulated sunlight irradiation (100 mW cm -2 , AM1.5) and dark-light conditions, respectively.

  2. Interaction of ultrashort laser pulses and silicon solar cells under short circuit conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mundus, M., E-mail: markus.mundus@ise.fraunhofer.de; Giesecke, J. A.; Fischer, P.; Hohl-Ebinger, J.; Warta, W. [Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstraße 2, 79110 Freiburg (Germany)

    2015-02-28

    Ultrashort pulse lasers are promising tools for numerous measurement purposes. Among other benefits their high peak powers allow for efficient generation of wavelengths in broad spectral ranges and at spectral powers that are orders of magnitude higher than in conventional light sources. Very recently this has been exploited for the establishment of sophisticated measurement facilities for electrical characterization of photovoltaic (PV) devices. As the high peak powers of ultrashort pulses promote nonlinear optical effects they might also give rise to nonlinear interactions with the devices under test that possibly manipulate the measurement outcome. In this paper, we present a comprehensive theoretical and experimental study of the nonlinearities affecting short circuit current (I{sub SC}) measurements of silicon (Si) solar cells. We derive a set of coupled differential equations describing the radiation-device interaction and discuss the nonlinearities incorporated in those. By a semi-analytical approach introducing a quasi-steady-state approximation and integrating a Green's function we solve the system of equations and obtain simulated I{sub SC} values. We validate the theoretical model by I{sub SC} ratios obtained from a double ring resonator setup capable for reproducible generation of various ultrashort pulse trains. Finally, we apply the model to conduct the most prominent comparison of I{sub SC} generated by ultrashort pulses versus continuous illumination. We conclude by the important finding that the nonlinearities induced by ultrashort pulses are negligible for the most common I{sub SC} measurements. However, we also find that more specialized measurements (e.g., of concentrating PV or Si-multijunction devices as well as highly localized electrical characterizations) will be biased by two-photon-absorption distorting the I{sub SC} measurement.

  3. Application of artificial neural network to search for gravitational-wave signals associated with short gamma-ray bursts

    International Nuclear Information System (INIS)

    Kim, Kyungmin; Lee, Hyun Kyu; Harry, Ian W; Hodge, Kari A; Kim, Young-Min; Lee, Chang-Hwan; Oh, John J; Oh, Sang Hoon; Son, Edwin J

    2015-01-01

    We apply a machine learning algorithm, the artificial neural network, to the search for gravitational-wave signals associated with short gamma-ray bursts (GRBs). The multi-dimensional samples consisting of data corresponding to the statistical and physical quantities from the coherent search pipeline are fed into the artificial neural network to distinguish simulated gravitational-wave signals from background noise artifacts. Our result shows that the data classification efficiency at a fixed false alarm probability (FAP) is improved by the artificial neural network in comparison to the conventional detection statistic. Specifically, the distance at 50% detection probability at a fixed false positive rate is increased about 8%–14% for the considered waveform models. We also evaluate a few seconds of the gravitational-wave data segment using the trained networks and obtain the FAP. We suggest that the artificial neural network can be a complementary method to the conventional detection statistic for identifying gravitational-wave signals related to the short GRBs. (paper)

  4. Globally coherent short duration magnetic field transients and their effect on ground based gravitational-wave detectors

    International Nuclear Information System (INIS)

    Kowalska-Leszczynska, Izabela; Bulik, Tomasz; Bizouard, Marie-Anne; Robinet, Florent; Christensen, Nelson; Rohde, Maximilian; Coughlin, Michael; Gołkowski, Mark; Kubisz, Jerzy; Kulak, Andrzej; Mlynarczyk, Janusz

    2017-01-01

    It has been recognized that the magnetic fields from the Schumann resonances could affect the search for a stochastic gravitational-wave background by LIGO and Virgo. Presented here are the observations of short duration magnetic field transients that are coincident in the magnetometers at the LIGO and Virgo sites. Data from low-noise magnetometers in Poland and Colorado, USA, are also used and show short duration magnetic transients of global extent. We measure at least 2.3 coincident (between Poland and Colorado) magnetic transient events per day where one of the pulses exceeds 200 pT. Given the recently measured values of the magnetic coupling to differential arm motion for Advanced LIGO, there would be a few events per day that would appear simultaneously at the gravitational-wave detector sites and could move the test masses of order 10 −18 m. We confirm that in the advanced detector era short duration transient gravitational-wave searches must account for correlated magnetic field noise in the global detector network. (paper)

  5. 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.

  6. Single-electron transport driven by surface acoustic waves: Moving quantum dots versus short barriers

    DEFF Research Database (Denmark)

    Utko, Pawel; Hansen, Jørn Bindslev; Lindelof, Poul Erik

    2007-01-01

    We have investigated the response of the acoustoelectric-current driven by a surface-acoustic wave through a quantum point contact in the closed-channel regime. Under proper conditions, the current develops plateaus at integer multiples of ef when the frequency f of the surface-acoustic wave...... or the gate voltage V-g of the point contact is varied. A pronounced 1.1 MHz beat period of the current indicates that the interference of the surface-acoustic wave with reflected waves matters. This is supported by the results obtained after a second independent beam of surface-acoustic wave was added......, traveling in opposite direction. We have found that two sub-intervals can be distinguished within the 1.1 MHz modulation period, where two different sets of plateaus dominate the acoustoelectric-current versus gate-voltage characteristics. In some cases, both types of quantized steps appeared simultaneously...

  7. Detection of Propagating Fast Sausage Waves through Detailed Analysis of a Zebra-pattern Fine Structure in a Solar Radio Burst

    Science.gov (United States)

    Kaneda, K.; Misawa, H.; Iwai, K.; Masuda, S.; Tsuchiya, F.; Katoh, Y.; Obara, T.

    2018-03-01

    Various magnetohydrodynamic (MHD) waves have recently been detected in the solar corona and investigated intensively in the context of coronal heating and coronal seismology. In this Letter, we report the first detection of short-period propagating fast sausage mode waves in a metric radio spectral fine structure observed with the Assembly of Metric-band Aperture Telescope and Real-time Analysis System. Analysis of Zebra patterns (ZPs) in a type-IV burst revealed a quasi-periodic modulation in the frequency separation between the adjacent stripes of the ZPs (Δf ). The observed quasi-periodic modulation had a period of 1–2 s and exhibited a characteristic negative frequency drift with a rate of 3–8 MHz s‑1. Based on the double plasma resonance model, the most accepted generation model of ZPs, the observed quasi-periodic modulation of the ZP can be interpreted in terms of fast sausage mode waves propagating upward at phase speeds of 3000–8000 km s‑1. These results provide us with new insights for probing the fine structure of coronal loops.

  8. Detector with internal gain for short-wave infrared ranging applications

    Science.gov (United States)

    Fathipour, Vala; Mohseni, Hooman

    2017-09-01

    Abstarct.Highly sensitive photon detectors are regarded as the key enabling elements in many applications. Due to the low photon energy at the short-wave infrared (SWIR), photon detection and imaging at this band are very challenging. As such, many efforts in photon detector research are directed toward improving the performance of the photon detectors operating in this wavelength range. To solve these problems, we have developed an electron-injection (EI) technique. The significance of this detection mechanism is that it can provide both high efficiency and high sensitivity at room temperature, a condition that is very difficult to achieve in conventional SWIR detectors. An EI detector offers an overall system-level sensitivity enhancement due to a feedback stabilized internal avalanche-free gain. Devices exhibit an excess noise of unity, operate in linear mode, require bias voltage of a few volts, and have a cutoff wavelength of 1700 nm. We review the material system, operating principle, and development of EI detectors. The shortcomings of the first-generation devices were addressed in the second-generation detectors. Measurement on second-generation devices showed a high-speed response of ˜6 ns rise time, low jitter of less than 20 ps, high amplification of more than 2000 (at optical power levels larger than a few nW), unity excess noise factor, and low leakage current (amplified dark current ˜10 nA at a bias voltage of -3 V and at room temperature. These characteristics make EI detectors a good candidate for high-resolution flash light detection and ranging (LiDAR) applications with millimeter scale depth resolution at longer ranges compared with conventional p-i-n diodes. Based on our experimentally measured device characteristics, we compare the performance of the EI detector with commercially available linear mode InGaAs avalanche photodiode (APD) as well as a p-i-n diode using a theoretical model. Flash LiDAR images obtained by our model show that the EI

  9. Short gamma-ray bursts and gravitational-wave observations from eccentric compact binaries

    Science.gov (United States)

    Tan, Wei-Wei; Fan, Xi-Long; Wang, F. Y.

    2018-03-01

    Mergers of compact binaries, such as binary neutron stars (BNSs), neutron star-black hole binaries (NSBHs) and binary black holes (BBHs), are expected to be the best candidates for sources of gravitational waves (GWs) and the leading theoretical models for short gamma-ray bursts (SGRBs). Based on observations of SGRBs, we can derive the merger rates of these compact binaries and study stochastic GW backgrounds (SGWBs) or the co-detection rates of GWs associated with SGRBs (GW-SGRBs). Before that, however, the most important thing is to derive the GW spectrum from a single GW source. Usually, a GW spectrum from a circular-orbit binary is assumed. However, observations of the large spatial offsets of SGRBs from their host galaxies imply that SGRB progenitors may be formed by dynamical processes and will merge with residual eccentricities (er). The orbital eccentricity has an important effect on GW spectra and therefore on the SGWB and GW-SGRB co-detection rate. Our results show that the power spectra of SGWBs from eccentric compact binaries are greatly suppressed at low frequencies (e.g. f ≲ 1 Hz). In particular, SGWBs from binaries with high residual eccentricities (e.g. er ≳ 0.1 for BNSs) will be hard to detect (above the detection frequency of ˜ 100 Hz). Regarding the co-detection rates of GW-SGRB events, they could be ˜1.4 times higher than the circular case within some particular ranges of er (e.g. 0.01 ≲ er ≲ 0.1 for BBHs), but greatly reduced for high residual eccentricities (e.g. er > 0.1 for BNSs). In general, BBH progenitors produce 200 and 10 times higher GW-SGRB events than BNS and NSBH progenitors, respectively. Therefore, binaries with low residual eccentricities (e.g. 0.001 ≲ er ≲ 0.1) and high total masses will be easier to detect by Advanced LIGO (aLIGO). However, only a small fraction of BBHs can be SGRB progenitors (if they can produce SGRBs), because the predicted GW-SGRB event rate (60˜100 per year) is too high compared with recent

  10. Supersonic Ionization Wave Driven by Radiation Transport in a Short-Pulse Laser-Produced Plasma

    International Nuclear Information System (INIS)

    Ditmire, T.; Gumbrell, E.T.; Smith, R.A.; Mountford, L.; Hutchinson, M.H.

    1996-01-01

    Through the use of an ultrashort (2ps) optical probe, we have time resolved the propagation of an ionization wave into solid fused silica. This ionization wave results when a plasma is created by the intense irradiation of a solid target with a 2ps laser pulse. We find that the velocity of the ionization wave is consistent with radiation driven thermal transport, exceeding the velocity expected from simple electron thermal conduction by nearly an order of magnitude. copyright 1996 The American Physical Society

  11. Experimental Study of Wave Forces on Vertical Circular Cylinders in Long and Short Crested Sea

    DEFF Research Database (Denmark)

    Høgedal, Michael

    on the safe side, as the directional spreading of the wave field Ieads to reduced horizontal velocities and acceleration; in the fluid and hence a reduction of the resultant and in-line wave forces on the structure. The directional spreading of the horizontal velocity field generally causes an increase...... with miniature pressure transducers. The experiments were carried out in the 3-D wave tank in the Hydraulics & Coastal Engineering Laboratory at Aalborg University and in the off-shore basin at the Danish Hydraulic Institute....

  12. Wavelet characterisation of ionospheric acoustic and gravity waves occuring during the solar eclipse of August 11, 1999

    Czech Academy of Sciences Publication Activity Database

    Šauli, Petra; Abry, P.; Boška, Josef; Duchayne, L.

    2006-01-01

    Roč. 68, 3-5 (2006), s. 586-598 ISSN 1364-6826 R&D Projects: GA ČR GP205/02/P077; GA ČR(CZ) GA205/01/1071; GA AV ČR(CZ) IAA3042102 Grant - others:CNRS(FR) 18098 Institutional research plan: CEZ:AV0Z30420517 Keywords : Solar eclipse * Acoustic-gravity waves * Vertical ionospheric sounding * Wavelet decomposition * Wave packet characterisation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.448, year: 2006

  13. Thermotolerance and Photosystem II Behaviour in Co-occuring Temperate Tree Species Exposed to Short-term Extreme Heat Waves

    Science.gov (United States)

    Guha, A.; Warren, J.; Cummings, C.; Han, J.

    2017-12-01

    Thermal stress can induce irreversible photodamage with longer consequences for plant metabolism. We focused on photosystem II (PSII) behaviour to understand how this complex responds in different co-occuring temperate trees exposed to short-term extreme heat waves. The study was designed for understanding complex heat tolerance mechanisms in trees. During manipulative heat-wave experiments, we monitored instantaneous PSII performance and tracked both transient and chronic PSII damages using chlorophyll a fluorescence characteristics. Fluorescence signals were used to simulate PSII bioenergetic processes. The light (Fv'/Fm') and dark-adapted (Fv/Fm) fluorescence traits including fast induction kinetics (OJIP), electron transport rate, PSII operating efficiency and quenching capacities were significantly affected by the heat treatments. Loss in PSII efficiency was more apparent in species like black cottonwood, yellow poplar, walnuts and conifers, whereas oaks maintained relatively better PSII functions. The post-heat recovery of Fv/Fm varied across the studied species showing differential carry over effects. PSII down-regulation was one of dominant factors for the loss in operational photosynthesis during extreme heat wave events. Both light and dark-adapted fluorescence characteristics showed loss in photo-regulatory functions and photodamage. Some resilient species showed rapid recovery from transient PSII damage, whereas fingerprints of chronic PSII damage were observed in susceptibles. Thresholds for Fv/Fm and non-photochemical quenching were identified for the studied species. PSII malfunctioning was largely associated with the observed photosynthetic down-regulation during heat wave treatments, however, its physiological recovery should be a key factor to determine species resilience to short-term extreme heat wave events.

  14. Observation of chorus waves by the Van Allen Probes: dependence on solar wind parameters and scale size

    Science.gov (United States)

    Aryan, H.; Sibeck, D. G.; Balikhin, M. A.; Agapitov, O. V.; Kletzing, C.

    2016-12-01

    Highly energetic electrons in the Earth's Van Allen radiation belts can cause serious damage to spacecraft electronic systems, and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are non-specific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters, but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity respectively. Results show that the average scale size of chorus wave packets is approximately 1300 - 2300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere, and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.

  15. Short Wave Part of Earth's Energy Budget at Top of Atmosphere During 2009-2017 from Radiometer IKOR-M Data

    Science.gov (United States)

    Cherviakov, M.; Spiryakhina, A.; Surkova, Y.; Kulkova, E.; Shishkina, E.

    2017-12-01

    This report describes Earth's energy budget IKOR-M satellite program which has been started in Russia. The first satellite "Meteor-M" No 1 of this project was put into orbit in 2009. The IKOR-M radiometer is a satellite instrument which can measure reflected shortwave radiation (0.3-4.0 µm). It was created in Saratov University and installed on Russian meteorological satellites "Meteor-M" No 1 and No 2. IKOR-M designed for satellite monitoring of the outgoing short-wave radiation at top-of-atmosphere (TOA), which is one of the components of Earth's energy budget. Such measurements can be used to derive albedo and absorbed solar radiation at TOA. The basic products of data processing are given in the form of global maps of distribution outgoing short-wave radiation, albedo and absorbed solar radiation (ASR). Such maps were made for each month during observation period. The IKOR-M product archive is available online at all times. A searchable catalogue of data products is continually updated and users may search and download data products via the Earth radiation balance components research laboratory website (www.sgu.ru/structure/geographic/metclim/balans) as soon as they become available. Two series of measurements from two different IKOR-M are available. The first radiometer had worked from October 2009 to August 2014 and second - from August 2014 to the present. Therefore, there is a period when both radiometers work at the same time. Top-of-atmosphere fluxes deduced from the "Meteor-M" No 1 measurements in August 2014 show very good agreement with the fluxes determined from "Meteor-M" No 2. It was shown that the albedo and ASR data received from the radiometer IKOR-M can be used to detect El Nino in the Pacific Ocean. During the radiometer operation, there were two significant El Nino events. Spatial-temporal distribution of the albedo in the equatorial part of the Pacific Ocean was analyzed. Region with high albedo values of 35-40 % is formed in the region 180E

  16. Radiophysical methods of diagnostics the Earth's ionosphere and the underlying earth's surface by remote sensing in the short-wave range of radio waves

    Science.gov (United States)

    Belov, S. Yu.; Belova, I. N.

    2017-11-01

    Monitoring of the earth's surface by remote sensing in the short-wave band can provide quick identification of some characteristics of natural systems. This band range allows one to diagnose subsurface aspects of the earth, as the scattering parameter is affected by irregularities in the dielectric permittivity of subsurface structures. This method based on the organization of the monitoring probe may detect changes in these environments, for example, to assess seismic hazard, hazardous natural phenomena such as earthquakes, as well as some man-made hazards and etc. The problem of measuring and accounting for the scattering power of the earth's surface in the short-range of radio waves is important for a number of purposes, such as diagnosing properties of the medium, which is of interest for geological, environmental studies. In this paper, we propose a new method for estimating the parameters of incoherent signal/noise ratio. The paper presents the results of comparison of the measurement method from the point of view of their admissible relative analytical errors. The new method is suggested. Analysis of analytical error of estimation of this parameter allowed to recommend new method instead of standard method. A comparative analysis and shows that the analytical (relative) accuracy of the determination of this parameter new method on the order exceeds the widely-used standard method.

  17. Summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    The diagrams in this section of the publication illustrate the summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow observed in Japan. For convenience, the observational results are arranged by the solar rotation number. The aim of this illustration is to disseminate an outline of daily events observed in Japan for the benefit of active research workers who plan to make detailed study of the specific solar and terrestrial events. Therefore, the illustrations do not show all observational results in Japan but only representative ones at some key stations in Japan. They will suffice for the present purpose. The method of illustration shown in the instruction on the next page is still a preliminary one, and it is subject to change resulting from the kind advice of the users of this part of the publication. We welcome any advice for making the data arrangement and expression better and more convenient. (auth.)

  18. Prediction and measurement of the electromagnetic environment of high-power medium-wave and short-wave broadcast antennas in far field.

    Science.gov (United States)

    Tang, Zhanghong; Wang, Qun; Ji, Zhijiang; Shi, Meiwu; Hou, Guoyan; Tan, Danjun; Wang, Pengqi; Qiu, Xianbo

    2014-12-01

    With the increasing city size, high-power electromagnetic radiation devices such as high-power medium-wave (MW) and short-wave (SW) antennas have been inevitably getting closer and closer to buildings, which resulted in the pollution of indoor electromagnetic radiation becoming worsened. To avoid such radiation exceeding the exposure limits by national standards, it is necessary to predict and survey the electromagnetic radiation by MW and SW antennas before constructing the buildings. In this paper, a modified prediction method for the far-field electromagnetic radiation is proposed and successfully applied to predict the electromagnetic environment of an area close to a group of typical high-power MW and SW wave antennas. Different from currently used simplified prediction method defined in the Radiation Protection Management Guidelines (H J/T 10. 3-1996), the new method in this article makes use of more information such as antennas' patterns to predict the electromagnetic environment. Therefore, it improves the prediction accuracy significantly by the new feature of resolution at different directions. At the end of this article, a comparison between the prediction data and the measured results is given to demonstrate the effectiveness of the proposed new method. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Comparative Study on KNN and SVM Based Weather Classification Models for Day Ahead Short Term Solar PV Power Forecasting

    Directory of Open Access Journals (Sweden)

    Fei Wang

    2017-12-01

    Full Text Available Accurate solar photovoltaic (PV power forecasting is an essential tool for mitigating the negative effects caused by the uncertainty of PV output power in systems with high penetration levels of solar PV generation. Weather classification based modeling is an effective way to increase the accuracy of day-ahead short-term (DAST solar PV power forecasting because PV output power is strongly dependent on the specific weather conditions in a given time period. However, the accuracy of daily weather classification relies on both the applied classifiers and the training data. This paper aims to reveal how these two factors impact the classification performance and to delineate the relation between classification accuracy and sample dataset scale. Two commonly used classification methods, K-nearest neighbors (KNN and support vector machines (SVM are applied to classify the daily local weather types for DAST solar PV power forecasting using the operation data from a grid-connected PV plant in Hohhot, Inner Mongolia, China. We assessed the performance of SVM and KNN approaches, and then investigated the influences of sample scale, the number of categories, and the data distribution in different categories on the daily weather classification results. The simulation results illustrate that SVM performs well with small sample scale, while KNN is more sensitive to the length of the training dataset and can achieve higher accuracy than SVM with sufficient samples.

  20. Radial direct bandgap p-i-n GaNP microwire solar cells with enhanced short circuit current

    Energy Technology Data Exchange (ETDEWEB)

    Sukrittanon, Supanee [Graduate Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Liu, Ren; Pan, Janet L. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Breeden, Michael C. [Department of Nanoengineering, University of California, San Diego, La Jolla, California 92037 (United States); Jungjohann, K. L. [Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Tu, Charles W., E-mail: ctu@ece.ucsd.edu, E-mail: sdayeh@ece.ucsd.edu; Dayeh, Shadi A., E-mail: ctu@ece.ucsd.edu, E-mail: sdayeh@ece.ucsd.edu [Graduate Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States)

    2016-08-07

    We report the demonstration of dilute nitride heterostructure core/shell microwire solar cells utilizing the combination of top-down reactive-ion etching to create the cores (GaP) and molecular beam epitaxy to create the shells (GaNP). Systematic studies of cell performance over a series of microwire lengths, array periods, and microwire sidewall morphologies examined by transmission electron microscopy were conducted to shed light on performance-limiting factors and to optimize the cell efficiency. We show by microscopy and correlated external quantum efficiency characterization that the open circuit voltage is degraded primarily due to the presence of defects at the GaP/GaNP interface and in the GaNP shells, and is not limited by surface recombination. Compared to thin film solar cells in the same growth run, the microwire solar cells exhibit greater short circuit current but poorer open circuit voltage due to greater light absorption and number of defects in the microwire structure, respectively. The comprehensive understanding presented in this work suggests that performance benefits of dilute nitride microwire solar cells can be achieved by further tuning of the epitaxial quality of the underlying materials.

  1. First simultaneous measurements of waves generated at the bow shock in the solar wind, the magnetosphere and on the ground

    Science.gov (United States)

    Clausen, L. B. N.; Yeoman, T. K.; Fear, R. C.; Behlke, R.; Lucek, E. A.; Engebretson, M. J.

    2009-01-01

    On 5 September 2002 the Geotail satellite observed the cone angle of the Interplanetary Magnetic Field (IMF) change to values below 30° during a 56 min interval between 18:14 and 19:10 UT. This triggered the generation of upstream waves at the bow shock, 13 RE downstream of the position of Geotail. Upstream generated waves were subsequently observed by Geotail between 18:30 and 18:48 UT, during times the IMF cone angle dropped below values of 10°. At 18:24 UT all four Cluster satellites simultaneously observed a sudden increase in wave power in all three magnetic field components, independent of their position in the dayside magnetosphere. We show that the 10 min delay between the change in IMF direction as observed by Geotail and the increase in wave power observed by Cluster is consistent with the propagation of the IMF change from the Geotail position to the bow shock and the propagation of the generated waves through the bow shock, magnetosheath and magnetosphere towards the position of the Cluster satellites. We go on to show that the wave power recorded by the Cluster satellites in the component containing the poloidal and compressional pulsations was broadband and unstructured; the power in the component containing toroidal oscillations was structured and shows the existence of multi-harmonic Alfvénic continuum waves on field lines. Model predictions of these frequencies fit well with the observations. An increase in wave power associated with the change in IMF direction was also registered by ground based magnetometers which were magnetically conjunct with the Cluster satellites during the event. To the best of our knowledge we present the first simultaneous observations of waves created by backstreaming ions at the bow shock in the solar wind, the dayside magnetosphere and on the ground.

  2. Solar Plasma Radio Emission in the Presence of Imbalanced Turbulence of Kinetic-Scale Alfvén Waves

    Science.gov (United States)

    Lyubchyk, O.; Kontar, E. P.; Voitenko, Y. M.; Bian, N. H.; Melrose, D. B.

    2017-09-01

    We study the influence of kinetic-scale Alfvénic turbulence on the generation of plasma radio emission in the solar coronal regions where the ratio β of plasma to magnetic pressure is lower than the electron-to-ion mass ratio me/mi. The present study is motivated by the phenomenon of solar type I radio storms that are associated with the strong magnetic field of active regions. The measured brightness temperature of the type I storms can be up to 10^{10} K for continuum emission, and can exceed 10^{11} K for type I bursts. At present, there is no generally accepted theory explaining such high brightness temperatures and some other properties of the type I storms. We propose a model with an imbalanced turbulence of kinetic-scale Alfvén waves that produce an asymmetric quasi-linear plateau on the upper half of the electron velocity distribution. The Landau damping of resonant Langmuir waves is suppressed and their amplitudes grow spontaneously above the thermal level. The estimated saturation level of Langmuir waves is high enough to generate observed type I radio emission at the fundamental plasma frequency. Harmonic emission does not appear in our model because the backward-propagating Langmuir waves undergo strong Landau damping. Our model predicts 100% polarization in the sense of the ordinary (o-) mode of type I emission.

  3. A new method for detection of the electron temperature in laser-plasma short wave cut off of stimulated Raman scattering spectrum

    International Nuclear Information System (INIS)

    Zhang Jiatai

    1994-01-01

    From the theory of stimulated Raman scattering (SRS) three wave interaction, a new method of detecting the electron temperature in laser-plasma is obtained. SRS spectrum obtained from Shenguang No. 12 Nd-laser experiments are analysed. Using the wave length of short wave cut off of SRS, the electron temperature in corona plasma region is calculated consistently. These results agree reasonable with X-ray spectrum experiments

  4. Bit rate and pulse width dependence of four-wave mixing of short optical pulses in semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Diez, S.; Mecozzi, A.; Mørk, Jesper

    1999-01-01

    We investigate the saturation properties of four-wave mixing of short optical pulses in a semiconductor optical amplifier. By varying the gain of the optical amplifier, we find a strong dependence of both conversion efficiency and signal-to-background ratio on pulse width and bit rate....... In particular, the signal-to-background ratio can be optimized for a specific amplifier gain. This behavior, which is coherently described in experiment and theory, is attributed to the dynamics of the amplified spontaneous emission, which is the main source of noise in a semiconductor optical amplifier....

  5. Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration Missions

    Science.gov (United States)

    Atwell, William; Tylka, Allan J.; Dietrich, William F.; Rojdev, Kristina; Matzkind, Courtney

    2016-01-01

    In an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.

  6. Widely-Tunable Parametric Short-Wave Infrared Transmitter for CO2 Trace Detection (POSTPRINT)

    Science.gov (United States)

    2013-01-01

    coefficient in nonlinear fiber by distant low-power FWM,” IEEE Photonics Society Summer Topical Meeting, paper WC1.1, Playa Del Carmen, Mexico (2010... traveling -wave construction (i.e. they are cavity-less), they circumvent all the impairments #140287 - $15.00 USD Received 3 Jan 2011; revised 16 Mar

  7. The effect of broad-band Alfven-cyclotron waves spectra on the preferential heating and differential acceleration of He{sup ++} ions in the solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Maneva, Y. G. [Department of Physics, Catholic University of America, Washington DC, 20064 (United States) and Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ofman, L. [Department of Physics, Catholic University of America, Washington, DC 20064 (United States) and Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Vinas, A. F. [Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-06-13

    In anticipation of results from inner heliospheric missions such as the Solar Orbiter and the Solar Probe we present the results from 1.5D hybrid simulations to study the role of magnetic fluctuations for the heating and differential acceleration of He{sup ++} ions in the solar wind. We consider the effects of nonlinear Alfven-cyclotron waves at different frequency regimes. Monochromatic nonlinear Alfven-alpha-cyclotron waves are known to preferentially heat and accelerate He{sup ++} ions in collisionless low beta plasma. In this study we demonstrate that these effects are preserved when higherfrequency monochromatic and broad-band spectra of Alfven-proton-cyclotron waves are considered. Comparison between several nonlinear monochromatic waves shows that the ion temperatures, anisotropies and relative drift are quantitatively affected by the shift in frequency. Including a broad-band wave-spectrum results in a significant reduction of both the parallel and the perpendicular temperature components for the He{sup ++} ions, whereas the proton heating is barely influenced, with the parallel proton temperature only slightly enhanced. The differential streaming is strongly affected by the available wave power in the resonant daughter ion-acoustic waves. Therefore for the same initial wave energy, the relative drift is significantly reduced in the case of initial wave-spectra in comparison to the simulations with monochromatic waves.

  8. Enhancement of short-circuit current density in polymer bulk heterojunction solar cells comprising plasmonic silver nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuzhao; Lin, Xiaofeng; Ou, Jiemei; Chen, Xudong, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education of China, Sun Yat-sen University, Guangzhou 510275 (China); Qing, Jian; Zhong, Zhenfeng; Zhou, Xiang, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn; Chen, Yujie, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Hu, Chenglong [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan 430056 (China)

    2014-03-24

    We demonstrate that the influence of plasmonic effects based on silver nanowires (Ag NWs) on the characteristics of polymer solar cells (PSCs). The solution-processed Ag NWs are situated at the interface of anode buffer layer and active layer, which could enhance the performance especially the photocurrent of PSCs by scattering, localized surface plasmon resonance, and surface plasmon polaritons. Plasmonic effects are confirmed by the enhancement of extinction spectra, external quantum efficiency, and steady state photoluminescence. Consequently, the short-circuit current density (J{sub sc}) and power conversion efficiency enhance about 24% and 18%, respectively, under AM1.5 illumination when Ag NWs plasmonic nanostructure incorporated into PSCs.

  9. Small-bandgap polymer solar cells with unprecedented short-circuit current density and high fill factor.

    Science.gov (United States)

    Choi, Hyosung; Ko, Seo-Jin; Kim, Taehyo; Morin, Pierre-Olivier; Walker, Bright; Lee, Byoung Hoon; Leclerc, Mario; Kim, Jin Young; Heeger, Alan J

    2015-06-03

    Small-bandgap polymer solar cells (PSCs) with a thick bulk heterojunction film of 340 nm exhibit high power conversion efficiencies of 9.40% resulting from high short-circuit current density (JSC ) of 20.07 mA cm(-2) and fill factor of 0.70. This remarkable efficiency is attributed to maximized light absorption by the thick active layer and minimized recombination by the optimized lateral and vertical morphology through the processing additive. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. 182Hf-182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

    DEFF Research Database (Denmark)

    Holst, Jesper Christian; Olsen, Mia Bjørg Stolberg; Paton, Chad

    2013-01-01

    provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182Hf–182W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with 26Al/27Al......Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., 26Al, 41Ca, and 182Hf) synthesized...... in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed...

  11. Parametric decay of current-driven Langmuir waves in plateau plasmas: Relevance to solar wind and foreshock events

    Science.gov (United States)

    Sauer, Konrad; Malaspina, David M.; Pulupa, Marc; Salem, Chadi S.

    2017-07-01

    Langmuir amplitude modulation in association with type III radio bursts is a well-known phenomenon since the beginning of space observations. It is commonly attributed to the superposition of beam-excited Langmuir waves and their backscattered counterparts as a result of parametric decay. The dilemma, however, is the discrepancy between fast beam relaxation and long-lasting Langmuir wave activity. Instead of starting with an unstable electron beam, our focus in this paper is on the nonlinear response of Langmuir oscillations that are driven after beam stabilization by the still persisting current of the (stable) two-electron plasma. The velocity distribution function of the second population forms a plateau (index h) with a point at which ∂fh/∂v ˜0 associated with weak damping over a more or less extended wave number range k. As shown by particle-in-cell simulations, this so-called plateau plasma drives primarily Langmuir oscillations at the plasma frequency (ωe) with k = 0 over long times without remarkable change of the distribution function. These Langmuir oscillations act as a pump wave for parametric decay by which an electron-acoustic wave slightly below ωe and a counterstreaming ion-acoustic wave are generated. Both high-frequency waves have nearly the same amplitude, which is given by the product of plateau density and velocity. Beating of these two wave types leads to pronounced Langmuir amplitude modulation, in reasonable agreement with solar wind and terrestrial foreshock observations made by the Wind spacecraft.

  12. Plasma flux and gravity waves in the midlatitude ionosphere during the solar eclipse of 20 May 2012

    Science.gov (United States)

    Chen, Gang; Wu, Chen; Huang, Xueqin; Zhao, Zhengyu; Zhong, Dingkun; Qi, Hao; Huang, Liang; Qiao, Lei; Wang, Jin

    2015-04-01

    The solar eclipse effects on the ionosphere are very complex. Except for the ionization decay due to the decrease of the photochemical process, the couplings of matter and energy between the ionosphere and the regions above and below will introduce much more disturbances. Five ionosondes in the Northeast Asia were used to record the midlatitude ionospheric responses to the solar eclipse of 20 May 2012. The latitude dependence of the eclipse lag was studied first. The foF2 response to the eclipse became slower with increased latitude. The response of the ionosphere at the different latitudes with the same eclipse obscuration differed from each other greatly. The plasma flux from the protonsphere was possibly produced by the rapid temperature drop in the lunar shadow to make up the ionization loss. The greater downward plasma flux was generated at higher latitude with larger dip angle and delayed the ionospheric response later. The waves in the foEs and the plasma frequency at the fixed height in the F layer are studied by the time period analytic method. The gravity waves of 43-51 min center period during and after the solar eclipse were found over Jeju and I-Cheon. The northward group velocity component of the gravity waves was estimated as ~108.7 m/s. The vertical group velocities between 100 and 150 km height over the two stations were calculated as ~5 and ~4.3 m/s upward respectively, indicating that the eclipse-induced gravity waves propagated from below the ionosphere.

  13. SUNWARD PROPAGATING ALFVÉN WAVES IN ASSOCIATION WITH SUNWARD DRIFTING PROTON BEAMS IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiansen; Pei, Zhongtian; Wang, Linghua; Tu, Chuanyi; Zhang, Lei [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, D-24118 Kiel (Germany); Salem, Chadi, E-mail: jshept@gmail.com [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2015-06-01

    Using measurements from the WIND spacecraft, here we report the observation of sunward propagating Alfvén waves (AWs) in solar wind that is magnetically disconnected from the Earth's bow shock. In the sunward magnetic field sector, we find a period lasting for more than three days in which there existed (during most time intervals) a negative correlation between the flow velocity and magnetic field fluctuations, thus indicating that the related AWs are mainly propagating sunward. Simultaneous observations of counter-streaming suprathermal electrons suggest that these sunward AWs may not simply be due to the deflection of an open magnetic field line. Moreover, no interplanetary coronal mass ejection appears to be associated with the counter-streaming suprathermal electrons. As the scale goes from the magnetohydrodynamic down to the ion kinetic regime, the wave vector of magnetic fluctuations usually becomes more orthogonal to the mean magnetic field direction, and the fluctuations become increasingly compressible, which are both features consistent with quasi-perpendicular kinetic AWs. However, in the case studied here, we find clear signatures of quasi-parallel sunward propagating ion-cyclotron waves. Concurrently, the solar wind proton velocity distribution reveals a sunward field-aligned beam that drifts at about the local Alfvén speed. This beam is found to run in the opposite direction of the normally observed (anti-sunward) proton beam, and is apparently associated with sunward propagating Alfvén/ion-cyclotron waves. The results and conclusions of this study enrich our knowledge of solar wind turbulence and foster our understanding of proton heating and acceleration within a complex magnetic field geometry.

  14. Observations of short period seismic scattered waves by small seismic arrays

    Directory of Open Access Journals (Sweden)

    M. Simini

    1997-06-01

    Full Text Available The most recent observations of well correlated seismic phases in the high frequency coda of local earthquakes recorded throughout the world are reported. In particular the main results, obtained on two active volcanoes, Teide and Deception, using small array are described. The ZLC (Zero Lag Cross-correlation method and polarization analysis have been applied to the data in order to distinguish the main phases in the recorded seismograms and their azimuths and apparent velocities. The results obtained at the Teide volcano demonstrate that the uncorrelated part of the seismograms may be produced by multiple scattering from randomly distributed heterogeneity, while the well correlated part, showing SH type polarization or the possible presence of Rayleigh surface waves, may be generated by single scattering by strong scatterers. At the Deception Volcano strong scattering, strongly focused in a precise direction, is deduced from the data. In that case, all the coda radiation is composed of surface waves.

  15. CONTRIBUTION OF VELOCITY VORTICES AND FAST SHOCK REFLECTION AND REFRACTION TO THE FORMATION OF EUV WAVES IN SOLAR ERUPTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongjuan; Liu, Siqing; Gong, Jiancun [Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Ning [School of Tourism and Geography, Yunnan Normal University, Kunming, Yunnan 650031 (China); Lin, Jun [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China)

    2015-06-01

    We numerically study the detailed evolutionary features of the wave-like disturbance and its propagation in the eruption. This work is a follow-up to Wang et al., using significantly upgraded new simulations. We focus on the contribution of the velocity vortices and the fast shock reflection and refraction in the solar corona to the formation of the EUV waves. Following the loss of equilibrium in the coronal magnetic structure, the flux rope exhibits rapid motions and invokes the fast-mode shock at the front of the rope, which then produces a type II radio burst. The expansion of the fast shock, which is associated with outward motion, takes place in various directions, and the downward expansion shows the reflection and the refraction as a result of the non-uniform background plasma. The reflected component of the fast shock propagates upward and the refracted component propagates downward. As the refracted component reaches the boundary surface, a weak echo is excited. The Moreton wave is invoked as the fast shock touches the bottom boundary, so the Moreton wave lags the type II burst. A secondary echo occurs in the area where reflection of the fast shock encounters the slow-mode shock, and the nearby magnetic field lines are further distorted because of the interaction between the secondary echo and the velocity vortices. Our results indicate that the EUV wave may arise from various processes that are revealed in the new simulations.

  16. Solar Activity from 2006 to 2014 and Short-term Forecasts of Solar Proton Events Using the ESPERTA Model

    Energy Technology Data Exchange (ETDEWEB)

    Alberti, T.; Lepreti, F. [Dipartimento di Fisica, Università della Calabria, Ponte P. Bucci, Cubo 31C, 87036, Rende (CS) (Italy); Laurenza, M.; Storini, M.; Consolini, G. [INAF-IAPS, Via del Fosso del Cavaliere 100, I-00133, Roma (Italy); Cliver, E. W., E-mail: tommaso.alberti@unical.it, E-mail: monica.laurenza@iaps.inaf.it [National Solar Observatory, Boulder, CO (United States)

    2017-03-20

    To evaluate the solar energetic proton (SEP) forecast model of Laurenza et al., here termed ESPERTA, we computed the input parameters (soft X-ray (SXR) fluence and ∼1 MHz radio fluence) for all ≥M2 SXR flares from 2006 to 2014. This database is outside the 1995–2005 interval on which ESPERTA was developed. To assess the difference in the general level of activity between these two intervals, we compared the occurrence frequencies of SXR flares and SEP events for the first six years of cycles 23 (1996 September–2002 September) and 24 (2008 December–2014 December). We found a reduction of SXR flares and SEP events of 40% and 46%, respectively, in the latter period. Moreover, the numbers of ≥M2 flares with high values of SXR and ∼1 MHz fluences (>0.1 J m{sup −2} and >6 × 10{sup 5} sfu × minute, respectively) are both reduced by ∼30%. A somewhat larger percentage decrease of these two parameters (∼40% versus ∼30%) is obtained for the 2006–2014 interval in comparison with 1995–2005. Despite these differences, ESPERTA performance was comparable for the two intervals. For the 2006–2014 interval, ESPERTA had a probability of detection (POD) of 59% (19/32) and a false alarm rate (FAR) of 30% (8/27), versus a POD = 63% (47/75) and an FAR = 42% (34/81) for the original 1995–2005 data set. In addition, for the 2006–2014 interval the median (average) warning time was estimated to be ∼2 hr (∼7 hr), versus ∼6 hr (∼9 hr), for the 1995–2005 data set.

  17. Development and Short-Range Testing of a 100 kW Side-Illuminated Millimeter-Wave Thermal Rocket

    Science.gov (United States)

    Bruccoleri, Alexander; Eilers, James A.; Lambot, Thomas; Parkin, Kevin

    2015-01-01

    The objective of the phase described here of the Millimeter-Wave Thermal Launch System (MTLS) Project was to launch a small thermal rocket into the air using millimeter waves. The preliminary results of the first MTLS flight vehicle launches are presented in this work. The design and construction of a small thermal rocket with a planar ceramic heat exchanger mounted along the axis of the rocket is described. The heat exchanger was illuminated from the side by a millimeter-wave beam and fed propellant from above via a small tank containing high pressure argon or nitrogen. Short-range tests where the rocket was launched, tracked, and heated with the beam are described. The rockets were approximately 1.5 meters in length and 65 millimeters in diameter, with a liftoff mass of 1.8 kilograms. The rocket airframes were coated in aluminum and had a parachute recovery system activated via a timer and Pyrodex. At the rocket heat exchanger, the beam distance was 40 meters with a peak power intensity of 77 watts per square centimeter. and a total power of 32 kilowatts in a 30 centimeter diameter circle. An altitude of approximately 10 meters was achieved. Recommendations for improvements are discussed.

  18. Study on Short-term Variability of Ship Responses in Waves

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam; Iseki, Toshio

    2015-01-01

    Short-term variability of ship responses is investigated by cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data is required for stable results of the spectral analysis. However, the phase lag between responses, in terms of the phase angle o...

  19. Study on Short-term Variability of Ship Responses in Waves

    DEFF Research Database (Denmark)

    Iseki, Toshio; Nielsen, Ulrik Dam

    2014-01-01

    Short-term variability of ship responses is investigated from the view point of cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data are required for stable spectral analysis. However, the phase angle of the cross-spectra has not been discus...

  20. Analysis of Overtopping Flow on Sea Dikes in Oblique and Short-Crested Waves

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Burcharth, Hans F.

    2013-01-01

    -empirical formulae for the estimation of flow depths and flow velocities across a dike. The results have been coupled to the actual erosion of the landward dike slope determined by full-scale 2D tests using the so-called “Overtopping Simulator”. This paper describes the results from 96 small-scale tests carried out...... directions on the dike, and the statistical distribution of individual flow parameters are needed to obtain more realistic estimates of dike erosion caused by wave overtopping....

  1. Testing the very-short-baseline neutrino anomalies at the solar sector

    Science.gov (United States)

    Palazzo, Antonio

    2011-06-01

    Motivated by the accumulating hints of new sterile neutrino species at the eV scale, we explore the consequences of such an hypothesis on the solar sector phenomenology. After introducing the theoretical formalism needed to describe the Mikheyev-Smirnov-Wolfenstein conversion of solar neutrinos in the presence of one (or more) sterile neutrino state(s) located “far” from the (ν1, ν2) “doublet”, we perform a quantitative analysis of the available experimental results, focusing on the electron neutrino mixing. We find that the present data posses a sensitivity to the amplitude of the lepton mixing matrix element Ue4—encoding the admixture of the electron neutrino with a new mass eigenstate—which is comparable to that achieved on the standard matrix element Ue3. In addition, and more importantly, our analysis evidences that, in a 4-flavor framework, the current preference for |Ue3|≠0 is indistinguishable from that for |Ue4|≠0, having both a similar statistical significance (which is ˜1.3σ adopting the old reactor fluxes determinations, and ˜1.8σ using their new estimates.) We also point out that, differently from the standard 3-flavor case, in a 3+1 scheme the Dirac CP-violating phases cannot be eliminated from the description of solar neutrino conversions.

  2. Influence of short-term solar disturbances on the fair weather conduction current

    Directory of Open Access Journals (Sweden)

    Elhalel Gal

    2014-01-01

    Full Text Available The fair weather atmospheric electrical current (Jz couples the ionosphere to the lower atmosphere and thus provides a route by which changes in solar activity can modify processes in the lower troposphere. This paper examines the temporal variations and spectral characteristics of continuous measurements of Jz conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35′ N, 34°45′ E, during two large CMEs, and during periods of increased solar wind density. Evidence is presented for the effects of geomagnetic storms and sub-storms on low latitude Jz during two coronal mass ejections (CMEs, on 24–25th October 2011 and 7–8th March 2012, when the variability in Jz increased by an order of magnitude compared to normal fair weather conditions. The dynamic spectrum of the increased Jz fluctuations exhibit peaks in the Pc5 frequency range. Similar low frequency characteristics occur during periods of enhanced solar wind proton density. During the October 2011 event, the periods of increased fluctuations in Jz lasted for 7 h and coincided with fluctuations of the inter-planetary magnetic field (IMF detected by the ACE satellite. We suggest downward mapping of ionospheric electric fields as a possible mechanism for the increased fluctuations.

  3. A New Method to Comprehensively Diagnose Shock Waves in the Solar Atmosphere Based on Simultaneous Spectroscopic and Imaging Observations

    Science.gov (United States)

    Ruan, Wenzhi; Yan, Limei; He, Jiansen; Zhang, Lei; Wang, Linghua; Wei, Yong

    2018-06-01

    Shock waves are believed to play an important role in plasma heating. The shock-like temporal jumps in radiation intensity and Doppler shift have been identified in the solar atmosphere. However, a quantitative diagnosis of the shocks in the solar atmosphere is still lacking, seriously hindering the understanding of shock dissipative heating of the solar atmosphere. Here, we propose a new method to realize the goal of the shock quantitative diagnosis, based on Rankine–Hugoniot equations and taking the advantages of simultaneous imaging and spectroscopic observations from, e.g., IRIS (Interface Region Imaging Spectrograph). Because of this method, the key parameters of shock candidates can be derived, such as the bulk velocity and temperature of the plasma in the upstream and downstream, the propagation speed and direction. The method is applied to the shock candidates observed by IRIS, and the overall characteristics of the shocks are revealed quantitatively for the first time. This method is also tested with the help of forward modeling, i.e., virtual observations of simulated shocks. The parameters obtained from the method are consistent with the parameters of the shock formed in the model and are independent of the viewing direction. Therefore, the method we proposed here is applicable to the quantitative and comprehensive diagnosis of the observed shocks in the solar atmosphere.

  4. Field and numerical study of wind and surface waves at short fetches

    Science.gov (United States)

    Baydakov, Georgy; Kuznetsova, Alexandra; Sergeev, Daniil; Papko, Vladislav; Kandaurov, Alexander; Vdovin, Maxim; Troitskaya, Yuliya

    2016-04-01

    Measurements were carried out in 2012-2015 from May to October in the waters of Gorky Reservoir belonging to the Volga Cascade. The methods of the experiment focus on the study of airflow in the close proximity to the water surface. The sensors were positioned at the oceanographic Froude buoy including five two-component ultrasonic sensors WindSonic by Gill Instruments at different levels (0.1, 0.85, 1.3, 2.27, 5.26 meters above the mean water surface level), one water and three air temperature sensors, and three-channel wire wave gauge. One of wind sensors (0.1 m) was located on the float tracking the waveform for measuring the wind speed in the close proximity to the water surface. Basic parameters of the atmospheric boundary layer (the friction velocity u∗, the wind speed U10 and the drag coefficient CD) were calculated from the measured profiles of wind speed. Parameters were obtained in the range of wind speeds of 1-12 m/s. For wind speeds stronger than 4 m/s CD values were lower than those obtained before (see eg. [1,2]) and those predicted by the bulk parameterization. However, for weak winds (less than 3 m/s) CD values considerably higher than expected ones. The new parameterization of surface drag coefficient was proposed on the basis of the obtained data. The suggested parameterization of drag coefficient CD(U10) was implemented within wind input source terms in WAVEWATCH III [3]. The results of the numerical experiments were compared with the results obtained in the field experiments on the Gorky Reservoir. The use of the new drag coefficient improves the agreement in significant wave heights HS [4]. At the same time, the predicted mean wave periods are overestimated using both built-in source terms and adjusted source terms. We associate it with the necessity of the adjusting of the DIA nonlinearity model in WAVEWATCH III to the conditions of the middle-sized reservoir. Test experiments on the adjusting were carried out. The work was supported by the

  5. Mode Conversion of Langmuir to Electromagnetic Waves with Parallel Inhomogeneity in the Solar Wind and the Corona

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Hwa; Cairns, Iver H.; Robinson, Peter A.

    2008-06-09

    Linear mode conversion of Langmuir waves to radiation near the plasma frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, laboratory plasma devices, and pulsars. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code with the density gradient parallel to the ambient magnetic field B0 for a range of incident Langmuir wavevectors. Our results include: (1) Both o- and x-mode waves are produced for Ω ∝ (ωL)1/3(ωc/ω) somewhat less than 1, contrary to previous ideas. Only o mode is produced for Ω and somewhat greater than 1.5. Here ωc is the (angular) electron cyclotron frequency, ω the angular wave frequency, and L the length scale of the (linear) density gradient. (2) In the unmagnetized limit, equal amounts of o- and x-mode radiation are produced. (3) The mode conversion window narrows as Ω increases. (4) As Ω increases the total electromagnetic field changes from linear to circular polarization, with the o- and x- mode signals remaining circularly polarized. (5) The conversion efficiency to the x mode decreases monotonically as Ω increases while the o-mode conversion efficiency oscillates due to an interference phenomenon between incoming and reflected Langmuir/z modes. (6) The total conversion efficiency for wave energy from the Langmuir/z mode to radiation is typically less than 10%, but the corresponding power efficiencies differ by the ratio of the group speeds for each mode and are of order 50 – 70%. (7) The interference effect and the disappearance of the x mode at Ω somewhat greater than 1 can be accounted for semiquantitatively using a WKB-like analysis. (8) Constraints on density turbulence are developed for the x mode to be generated and be able to propagate from the source. (9) Standard parameters for the corona and the solar wind near 1 AU suggest that linear mode conversion should produce both o- and x- mode radiation for

  6. Mode Conversion of Langmuir to Electromagnetic Waves with Parallel Inhomogeneity in the Solar Wind and the Corona

    International Nuclear Information System (INIS)

    Kim, Eun-Hwa; Cairns, Iver H.; Robinson, Peter A.

    2008-01-01

    Linear mode conversion of Langmuir waves to radiation near the plasma frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, laboratory plasma devices, and pulsars. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code with the density gradient parallel to the ambient magnetic field B0 for a range of incident Langmuir wavevectors. Our results include: (1) Both o- and x-mode waves are produced for (Omega) ∝ (ωL) 1/3 (ω c /ω) ∼ 1.5. Here ω c is the (angular) electron cyclotron frequency, ω the angular wave frequency, and L the length scale of the (linear) density gradient. (2) In the unmagnetized limit, equal amounts of o- and x-mode radiation are produced. (3) The mode conversion window narrows as (Omega) increases. (4) As (Omega) increases the total electromagnetic field changes from linear to circular polarization, with the o- and x- mode signals remaining circularly polarized. (5) The conversion efficiency to the x mode decreases monotonically as (Omega) increases while the o-mode conversion efficiency oscillates due to an interference phenomenon between incoming and reflected Langmuir/z modes. (6) The total conversion efficiency for wave energy from the Langmuir/z mode to radiation is typically less than 10%, but the corresponding power efficiencies differ by the ratio of the group speeds for each mode and are of order 50-70%. (7) The interference effect and the disappearance of the x mode at (Omega) ∼> 1 can be accounted for semiquantitatively using a WKB-like analysis. (8) Constraints on density turbulence are developed for the x mode to be generated and be able to propagate from the source. (9) Standard parameters for the corona and the solar wind near 1 AU suggest that linear mode conversion should produce both o- and x- mode radiation for solar and interplanetary radio bursts. It is therefore possible that linear mode conversion

  7. Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, G. Q.; Feng, H. Q. [Institute of Space Physics, Luoyang Normal University, Luoyang (China); Wu, D. J. [Purple Mountain Observatory, CAS, Nanjing (China); Chu, Y. H. [Institute of Space Science, National Central University, Chungli, Taiwan (China); Huang, J. [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing (China)

    2017-09-20

    Previous studies revealed that electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency exist widely in the solar wind, and the majority of ECWs are left-handed (LH) polarized waves. Using the magnetic field data from the STEREO mission, this Letter carries out a survey of ECWs over a long period of 7 years and calculates the occurrence rates of ECWs with different polarization senses. Results show that the occurrence rate is nearly a constant for the ECWs with right-handed polarization, but it varies significantly for the ECWs with LH polarization. Further investigation of plasma conditions reveals that the LH ECWs take place preferentially in a plasma characterized by higher temperature, lower density, and larger velocity. Some considerable correlations between the occurrence rate of LH ECWs and the properties of ambient plasmas are discussed. The present research may provide evidence for the effect of alpha particles on the generation of ECWs.

  8. Possibility of obtaining coherent short wave radiation from a solid state free electron laser

    International Nuclear Information System (INIS)

    Bogacz, S.A.; Ketterson, J.B.

    1986-03-01

    The idea of using a crystal lattice or a superlattice as an undulator for a free electron laser is explored. A purely classical treatment of relativistic positrons channeling through the proposed structure involving a self consistent solution of the wave equation for the radiating electromagnetic field and the kinetic equation for the positron distribution function leads to a positive gain coefficient for a forward radiating field. Matching the Kumakhov resonance to the undulator frequency further enhances the gain. This result, combined with a feedback mechanism arising from Bragg diffraction within the basic crystal lattice, leads to an instability of the radiation inside the crystal. Finally a numerical estimate of the Kumakhov-enhanced gain coefficient is made for the (110) planar channeling in a strain modulated Si superlattice. 8 refs., 4 figs

  9. EVIDENCE OF THERMAL CONDUCTION SUPPRESSION IN A SOLAR FLARING LOOP BY CORONAL SEISMOLOGY OF SLOW-MODE WAVES

    International Nuclear Information System (INIS)

    Wang, Tongjiang; Ofman, Leon; Provornikova, Elena; Sun, Xudong; Davila, Joseph M.

    2015-01-01

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 Å images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ∼12 minutes and a decay time of ∼9 minutes. The measured phase speed of 500 ± 50 km s −1 matches the sound speed in the heated loop of ∼10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an ideal monatomic gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit

  10. Short term effect of air pollution, noise and heat waves on preterm births in Madrid (Spain).

    Science.gov (United States)

    Arroyo, Virginia; Díaz, Julio; Ortiz, Cristina; Carmona, Rocío; Sáez, Marc; Linares, Cristina

    2016-02-01

    Preterm birth (PTB) refers to delivery before 37 weeks of gestation and represents the leading cause of early-life mortality and morbidity in developed countries. PTB can lead to serious infant health outcomes. The etiology of PTB remains uncertain, but epidemiologic studies have consistently shown elevated risks with different environmental variables as traffic-related air pollution (TRAP). The aim of the study was to evaluate with time series methodology the short-term effect of air pollutants, noise levels and ambient temperature on the number of births and preterm births occurred in Madrid City during the 2001-2009 period. A time-series analysis was performed to assess the short term impact of daily mean concentrations (µg/m(3)) of PM2.5 and PM10, O3 and NO2. Measurements of Acoustic Pollution in dB(A) analyzed were: Leqd, equivalent diurnal noise level and Leqn, equivalent nocturnal noise level. Maximum and Minimum daily temperature (°C), mean Humidity in the air (%) and Atmospheric Pressure (HPa), were included too. Linear trends, seasonality, as well as the autoregressive nature of the series itself were controlled. We added as covariate the day of the week too. Autoregressive over-dispersed Poisson regression models were performed and the environmental variables were included with short-term lags (from 0 to 7 days) in reference to the date of birth. Firstly, simple models for the total number of births and preterm births were done separately. In a second stage, a model for total births adjusted for preterm births was performed. A total of 298,705 births were analyzed. The results of the final models were expressed in relative risks (RRs) for interquartile increase. We observed evidence of a short term effect at Lag 0, for the following environmental variables analyzed, PM2.5 (RR: 1.020; 95% CI:(1.008 1.032)) and O3 (RR: 1.012; 95% CI:(1.002 1.022)) concentrations and Leqd (RR: 1.139; 95% CI:( (1.124 1.154)) for the total number of births, and besides

  11. [Determination of fat, protein and DM in raw milk by portable short-wave near infrared spectrometer].

    Science.gov (United States)

    Li, Xiao-yun; Wang, Jia-hua; Huang, Ya-wei; Han, Dong-hai

    2011-03-01

    Near infrared diffuse reflectance spectroscopy calibrations of fat, protein and DM in raw milk were studied with partial least-squares (PLS) regression using portable short-wave near infrared spectrometer. The results indicated that good calibrations of fat and DM were found, the correlation coefficients were all 0.98, the RMSEC were 0.187 and 0.217, RMSEP were 0.187 and 0.296, the RPDs were 5.02 and 3.20 respectively; the calibration of protein needed to be improved but can be used for practice, the correlation coefficient was 0.95, RMSEC was 0.105, RMSEP was 0.120, and RPD was 2.60. Furthermore, the measuring accuracy was improved by analyzing the correction relation of fat and DM in raw milk This study will probably provide a new on-site method for nondestructive and rapid measurement of milk.

  12. Liquid film and interfacial wave behavior in air-water countercurrent flow through vertical short multi-tube geometries

    International Nuclear Information System (INIS)

    Zhang, Jinzhao; Giot, M.

    1992-01-01

    A series of experiments has been performed on air-water countercurrent flow through short multi-tube geometries (tube number n = 3, diameter d = 36mm, length I = 2d, 10d and 20d). The time-varying thicknesses of the liquid films trickling down the individual tubes are measured by means of conductance probes mounted flush at different locations of the inner wall surfaces. Detailed time series analyses of the measured film thicknesses provide some useful information about the film flow behavior as well as the interfacial wave characteristics in individual tubes, which can be used as some guidelines for developing more general predictive flooding models. 18 refs., 18 figs., 1 tabs

  13. Short-time fourth-order squeezing effects in spontaneous and stimulated four- and six-wave mixing processes

    International Nuclear Information System (INIS)

    Giri, Dilip Kumar; Gupta, P S

    2003-01-01

    The concept of fourth-order squeezing of the electromagnetic field is investigated in the fundamental mode in spontaneous and stimulated four- and six-wave mixing processes under the short-time approximation based on a fully quantum mechanical approach. The coupled Heisenberg equations of motion involving real and imaginary parts of the quadrature operators are established. The possibility of obtaining fourth-order squeezing is studied. The dependence of fourth-order squeezing on the number of photons is also investigated. It is shown that fourth-order squeezing, which is a higher-order squeezing, allows a much larger fractional noise reduction than lower-order squeezing. It is shown that squeezing is greater in a stimulated process than the corresponding squeezing in spontaneous interaction. The conditions for obtaining maximum and minimum squeezing are obtained. We have also established the non-classical nature of squeezed radiation using the Glauber-Sudarshan representation

  14. High-energy Neutrino Emission from Short Gamma-Ray Bursts: Prospects for Coincident Detection with Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Shigeo S.; Murase, Kohta; Mészáros, Peter [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Kiuchi, Kenta [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto, Kyoto 606-8502 (Japan)

    2017-10-10

    We investigate current and future prospects for coincident detection of high-energy neutrinos and gravitational waves (GWs). Short gamma-ray bursts (SGRBs) are believed to originate from mergers of compact star binaries involving neutron stars. We estimate high-energy neutrino fluences from prompt emission, extended emission (EE), X-ray flares, and plateau emission, and we show that neutrino signals associated with the EE are the most promising. Assuming that the cosmic-ray loading factor is ∼10 and the Lorentz factor distribution is lognormal, we calculate the probability of neutrino detection from EE by current and future neutrino detectors, and we find that the quasi-simultaneous detection of high-energy neutrinos, gamma-rays, and GWs is possible with future instruments or even with current instruments for nearby SGRBs having EE. We also discuss stacking analyses that will also be useful with future experiments such as IceCube-Gen2.

  15. The Short Wave Aerostat-Mounted Imager (SWAMI): A novel platform for acquiring remotely sensed data from a tethered balloon

    Science.gov (United States)

    Vierling, L.A.; Fersdahl, M.; Chen, X.; Li, Z.; Zimmerman, P.

    2006-01-01

    We describe a new remote sensing system called the Short Wave Aerostat-Mounted Imager (SWAMI). The SWAMI is designed to acquire co-located video imagery and hyperspectral data to study basic remote sensing questions and to link landscape level trace gas fluxes with spatially and temporally appropriate spectral observations. The SWAMI can fly at altitudes up to 2 km above ground level to bridge the spatial gap between radiometric measurements collected near the surface and those acquired by other aircraft or satellites. The SWAMI platform consists of a dual channel hyperspectral spectroradiometer, video camera, GPS, thermal infrared sensor, and several meteorological and control sensors. All SWAMI functions (e.g. data acquisition and sensor pointing) can be controlled from the ground via wireless transmission. Sample data from the sampling platform are presented, along with several potential scientific applications of SWAMI data.

  16. Short-wave infrared barriode detectors using InGaAsSb absorption material lattice matched to GaSb

    Energy Technology Data Exchange (ETDEWEB)

    Craig, A. P.; Percy, B.; Marshall, A. R. J. [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Jain, M. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Wicks, G.; Hossain, K. [Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); Golding, T. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); McEwan, K.; Howle, C. [Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ (United Kingdom)

    2015-05-18

    Short-wave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In{sub 0.28}Ga{sub 0.72}As{sub 0.25}Sb{sub 0.75} allowed for lattice matching to GaSb and cut-off wavelengths of 2.9 μm at 250 K and 3.0 μm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7×10{sup 10} Jones and 1×10{sup 10} Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures.

  17. Water vapor radiative effects on short-wave radiation in Spain

    Science.gov (United States)

    Vaquero-Martínez, Javier; Antón, Manuel; Ortiz de Galisteo, José Pablo; Román, Roberto; Cachorro, Victoria E.

    2018-06-01

    In this work, water vapor radiative effect (WVRE) is studied by means of the Santa Barbara's Disort Radiative Transfer (SBDART) model, fed with integrated water vapor (IWV) data from 20 ground-based GPS stations in Spain. Only IWV data recorded during cloud-free days (selected using daily insolation data) were used in this study. Typically, for SZA = 60.0 ± 0.5° WVRE values are around - 82 and - 66 Wm-2 (first and third quartile), although it can reach up - 100 Wm-2 or decrease to - 39 Wm-2. A power dependence of WVRE on IWV and cosine of solar zenith angle (SZA) was found by an empirical fit. This relation is used to determine the water vapor radiative efficiency (WVEFF = ∂WVRE/∂IWV). Obtained WVEFF values range from - 9 and 0 Wm-2 mm-1 (- 2.2 and 0% mm-1 in relative terms). It is observed that WVEFF decreases as IWV increases, but also as SZA increases. On the other hand, when relative WVEFF is calculated from normalized WVRE, an increase of SZA results in an increase of relative WVEFF. Heating rates were also calculated, ranging from 0.2 Kday-1 to 1.7 Kday-1. WVRE was also calculated at top of atmosphere, where values ranged from 4 Wm-2 to 37 Wm-2.

  18. GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

    NARCIS (Netherlands)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Phythian-Adams, A.T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.T.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, R.D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Bejger, M.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, M.J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, A.L.S.; Bock, O.; Boer, M.; Bogaert, J.G.; Bogan, C.; Bohe, A.; Bond, T.C; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, A.D.; Brown, D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderon; Callister, T. A.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglia, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Baiardi, L. Cerboni; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, D. S.; Charlton, P.; Chassande-Mottin, E.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Qian; Chua, S. E.; Chung, E.S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P. -F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, A.C.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, A.L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dasgupta, A.; Costa, C. F. Da Silva; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; De, S.; Debra, D.; Debreczeni, G.; Degallaix, J.; De laurentis, M.; Deleglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.A.; Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devine, R. C.; Dhurandhar, S.; Diaz, M. C.; Di Fiore, L.; Giovanni, M.G.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H. -B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, T. M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.M.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Fenyvesi, E.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M; Fong, H.; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Geng, P.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.P.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzalez, Idelmis G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Lee-Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.M.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Buffoni-Hall, R.; Hall, E. D.; Hamilton-Ayers, M.; Hammond, G.L.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, P.J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C. -J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.A.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J. -M.; Isi, M.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, D.H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jian, L.; Jimenez-Forteza, F.; Johnson, W.; Johnson-McDaniel, N. K.; Jones, I.D.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.H.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kefelian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.E.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan., S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chi-Woong; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Namjun; Kim, W.; Kim, Y.M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kissel, J. S.; Klein, B.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Krolak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C.H.; Lee, K.H.; Lee, M.H.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Lewis, J. B.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Lombardi, A. L.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lueck, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Zertuche, L. Magana; Magee, R. M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marka, S.; Marka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A. L.; Miller, B.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B.C.; Moore, J.C.; Moraru, D.; Gutierrez Moreno, M.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, S.D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P.G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Nedkova, K.; Nelemans, G.; Nelson, T. J. N.; Gutierrez-Neri, M.; Neunzert, A.; Newton-Howes, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J.; Oh, S. H.; Ohme, F.; Oliver, M. B.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.S; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Puerrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Riles, K.; Rizzo, D.M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosinska, D.; Rowan, S.; Ruediger, A.; Ruggi, P.; Ryan, K.A.; Sachdev, P.S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J; Schmidt, P.; Schnabel, R.B.; Schofield, R. M. S.; Schoenbeck, A.; Schreiber, K.E.C.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, M.S.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Setyawati, Y.; Shaddock, D. A.; Shaffer, T. J.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, António Dias da; Singer, A; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, R. J. E.; Smith, N.D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stevenson-Moore, P.; Stone, J.R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepanczyk, M. J.; Tacca, M.D.; Talukder, D.; Tanner, D. B.; Tapai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, W.R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tomlinson, C.; Tonelli, M.; Tornasi, Z.; Torres, C. V.; Torrie, C. I.; Toyra, D.; Travasso, F.; Traylor, G.; Trifiro, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; Van Beuzekom, Martin; van den Brand, J. F. J.; Van Den Broeck, C.F.F.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasuth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P.J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Vicere, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, MT; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.M.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Williams, D.R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Worden, J.; Wright, J.L.; Wu, D.S.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yu, H.; Yvert, M.; Zadrozny, A.; Zangrando, L.; Zanolin, M.; Zendri, J. -P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Boyle, M.; Hemberger, D.; Kidder, L. E.; Lovelace, G.; Ossokine, S.; Scheel, M.; Szilagyi, B.; Teukolsky, S.

    2016-01-01

    We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was

  19. Performance of InGaAs short wave infrared avalanche photodetector for low flux imaging

    Science.gov (United States)

    Singh, Anand; Pal, Ravinder

    2017-11-01

    Opto-electronic performance of the InGaAs/i-InGaAs/InP short wavelength infrared focal plane array suitable for high resolution imaging under low flux conditions and ranging is presented. More than 85% quantum efficiency is achieved in the optimized detector structure. Isotropic nature of the wet etching process poses a challenge in maintaining the required control in the small pitch high density detector array. Etching process is developed to achieve low dark current density of 1 nA/cm2 in the detector array with 25 µm pitch at 298 K. Noise equivalent photon performance less than one is achievable showing single photon detection capability. The reported photodiode with low photon flux is suitable for active cum passive imaging, optical information processing and quantum computing applications.

  20. Medium and Short Wave RF Energy Harvester for Powering Wireless Sensor Networks.

    Science.gov (United States)

    Leon-Gil, Jesus A; Cortes-Loredo, Agustin; Fabian-Mijangos, Angel; Martinez-Flores, Javier J; Tovar-Padilla, Marco; Cardona-Castro, M Antonia; Morales-Sánchez, Alfredo; Alvarez-Quintana, Jaime

    2018-03-03

    Internet of Things (IoT) is an emerging platform in which every day physical objects provided with unique identifiers are connected to the Internet without requiring human interaction. The possibilities of such a connected world enables new forms of automation to make our lives easier and safer. Evidently, in order to keep billions of these communicating devices powered long-term, a self-sustainable operation is a key point for realization of such a complex network. In this sense, energy-harvesting technologies combined with low power consumption ICs eliminate the need for batteries, removing an obstacle to the success of the IoT. In this work, a Radio Frequency (RF) energy harvester tuned at AM broadcast has been developed for low consumption power devices. The AM signals from ambient are detected via a high-performance antenna-free LC circuit with an efficiency of 3.2%. To maximize energy scavenging, the RF-DC conversion stage is based on a full-wave Cockcroft-Walton voltage multiplier (CWVM) with efficiency up to 90%. System performance is evaluated by rating the maximum power delivered into the load via its output impedance, which is around 62 μW, although power level seems to be low, it is able to power up low consumption devices such as Leds, portable calculators and weather monitoring stations.

  1. Physiological responses and toxin production of Microcystis aeruginosa in short-term exposure to solar UV radiation.

    Science.gov (United States)

    Hernando, Marcelo; Minaglia, Melina Celeste Crettaz; Malanga, Gabriela; Houghton, Christian; Andrinolo, Darío; Sedan, Daniela; Rosso, Lorena; Giannuzzi, Leda

    2018-01-17

    The aim of this study was to evaluate the effects of short-term (hours) exposure to solar UV radiation (UVR, 280-400 nm) on the physiology of Microcystis aeruginosa. Three solar radiation treatments were implemented: (i) PAR (PAR, 400-700 nm), (ii) TUVA (PAR + UVAR, 315-700 nm) and (iii) TUVR (PAR + UVAR + UVBR, 280-700 nm). Differential responses of antioxidant enzymes and the reactive oxygen species (ROS) production to UVR were observed. Antioxidant enzymes were more active at high UVR doses. However, different responses were observed depending on the exposure to UVAR or UVBR and the dose level. No effects were observed on the biomass, ROS production or increased activity of superoxide dismutase (SOD) and catalase (CAT) compared to the control when UVR + PAR doses were lower than 9875 kJ m -2 . For intermediate doses, UVR + PAR doses between 9875 and 10 275 kJ m -2 , oxidative stress increased while resistance was imparted through SOD and CAT in the cells exposed to UVAR. Despite the increased antioxidant activity, biomass decrease and photosynthesis inhibition were observed, but no effects were observed with added exposure to UVBR. At the highest doses (UVR + PAR higher than 10 275 kJ m -2 ), the solar UVR caused decreased photosynthesis and biomass with only activation of CAT by UVBR and SOD and CAT by UVAR. In addition, for such doses, a significant decrease of microcystins (MCs, measured as MC-LR equivalents) was observed as a consequence of UVAR. This study facilitates our understanding of the SOD and CAT protection according to UVAR and UVBR doses and cellular damage and reinforces the importance of UVR as an environmental stressor. In addition, our results support the hypothesized antioxidant function of MCs.

  2. Performance Feedback & Control of Solar Concentrators Using Wave Front Sensing Techniques (Preprint)

    National Research Council Canada - National Science Library

    Beasley, Jason N

    2007-01-01

    The major requirement for using concentrating Solar Thermal devices is the proper placement of the focal spot on the absorber to provide heating of the working fluid to produce thrust or to generate electricity...

  3. Short-term solar irradiance forecasting and photovoltaic systems performance in a tropical climate in Singapore

    OpenAIRE

    Nobre, André Maia

    2015-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Civil, Florianópolis, 2015. A humanidade usou e continua consumindo em grande quantidade os recursos não-renováveis do planeta como petróleo, gás natural e carvão mineral para suprir suas necessidades energéticas. Somente nas últimas duas décadas que outras fontes de energia renováveis, como a solar fotovoltaica e a eólica, passaram a se tornar relevantes na...

  4. Visible, Very Near IR and Short Wave IR Hyperspectral Drone Imaging System for Agriculture and Natural Water Applications

    Science.gov (United States)

    Saari, H.; Akujärvi, A.; Holmlund, C.; Ojanen, H.; Kaivosoja, J.; Nissinen, A.; Niemeläinen, O.

    2017-10-01

    The accurate determination of the quality parameters of crops requires a spectral range from 400 nm to 2500 nm (Kawamura et al., 2010, Thenkabail et al., 2002). Presently the hyperspectral imaging systems that cover this wavelength range consist of several separate hyperspectral imagers and the system weight is from 5 to 15 kg. In addition the cost of the Short Wave Infrared (SWIR) cameras is high (  50 k€). VTT has previously developed compact hyperspectral imagers for drones and Cubesats for Visible and Very near Infrared (VNIR) spectral ranges (Saari et al., 2013, Mannila et al., 2013, Näsilä et al., 2016). Recently VTT has started to develop a hyperspectral imaging system that will enable imaging simultaneously in the Visible, VNIR, and SWIR spectral bands. The system can be operated from a drone, on a camera stand, or attached to a tractor. The targeted main applications of the DroneKnowledge hyperspectral system are grass, peas, and cereals. In this paper the characteristics of the built system are shortly described. The system was used for spectral measurements of wheat, several grass species and pea plants fixed to the camera mount in the test fields in Southern Finland and in the green house. The wheat, grass and pea field measurements were also carried out using the system mounted on the tractor. The work is part of the Finnish nationally funded DroneKnowledge - Towards knowledge based export of small UAS remote sensing technology project.

  5. SUPRATHERMAL ELECTRON STRAHL WIDTHS IN THE PRESENCE OF NARROW-BAND WHISTLER WAVES IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Kajdič, P. [Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico City (Mexico); Alexandrova, O.; Maksimovic, M.; Lacombe, C. [LESIA, Observatoire de Paris, PSL Research University, CNRS, UPMC UniversitéParis 06, Université Paris-Diderot, 5 Place Jules Janssen, F-92190 Meudon (France); Fazakerley, A. N., E-mail: primoz@geofisica.unam.mx [Mullard Space Science Laboratory, University College London (United Kingdom)

    2016-12-20

    We perform the first statistical study of the effects of the interaction of suprathermal electrons with narrow-band whistler mode waves in the solar wind (SW). We show that this interaction does occur and that it is associated with enhanced widths of the so-called strahl component. The latter is directed along the interplanetary magnetic field away from the Sun. We do the study by comparing the strahl pitch angle widths in the SW at 1 AU in the absence of large scale discontinuities and transient structures, such as interplanetary shocks, interplanetary coronal mass ejections, stream interaction regions, etc. during times when the whistler mode waves were present and when they were absent. This is done by using the data from two Cluster instruments: Spatio Temporal Analysis of Field Fluctuations experiment (STAFF) data in the frequency range between ∼0.1 and ∼200 Hz were used for determining the wave properties and Plasma Electron And Current Experiment (PEACE) data sets at 12 central energies between ∼57 eV (equivalent to ∼10 typical electron thermal energies in the SW, E{sub T}) and ∼676 eV (∼113 E{sub T}) for pitch angle measurements. Statistical analysis shows that, during the intervals with the whistler waves, the strahl component on average exhibits pitch angle widths between 2° and 12° larger than during the intervals when these waves are not present. The largest difference is obtained for the electron central energy of ∼344 eV (∼57 ET).

  6. SUPRATHERMAL ELECTRON STRAHL WIDTHS IN THE PRESENCE OF NARROW-BAND WHISTLER WAVES IN THE SOLAR WIND

    International Nuclear Information System (INIS)

    Kajdič, P.; Alexandrova, O.; Maksimovic, M.; Lacombe, C.; Fazakerley, A. N.

    2016-01-01

    We perform the first statistical study of the effects of the interaction of suprathermal electrons with narrow-band whistler mode waves in the solar wind (SW). We show that this interaction does occur and that it is associated with enhanced widths of the so-called strahl component. The latter is directed along the interplanetary magnetic field away from the Sun. We do the study by comparing the strahl pitch angle widths in the SW at 1 AU in the absence of large scale discontinuities and transient structures, such as interplanetary shocks, interplanetary coronal mass ejections, stream interaction regions, etc. during times when the whistler mode waves were present and when they were absent. This is done by using the data from two Cluster instruments: Spatio Temporal Analysis of Field Fluctuations experiment (STAFF) data in the frequency range between ∼0.1 and ∼200 Hz were used for determining the wave properties and Plasma Electron And Current Experiment (PEACE) data sets at 12 central energies between ∼57 eV (equivalent to ∼10 typical electron thermal energies in the SW, E T ) and ∼676 eV (∼113 E T ) for pitch angle measurements. Statistical analysis shows that, during the intervals with the whistler waves, the strahl component on average exhibits pitch angle widths between 2° and 12° larger than during the intervals when these waves are not present. The largest difference is obtained for the electron central energy of ∼344 eV (∼57 ET).

  7. The influence of solar wind on extratropical cyclones – Part 2: A link mediated by auroral atmospheric gravity waves?

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    2009-01-01

    Full Text Available Cases of mesoscale cloud bands in extratropical cyclones are observed a few hours after atmospheric gravity waves (AGWs are launched from the auroral ionosphere. It is suggested that the solar-wind-generated auroral AGWs contribute to processes that release instabilities and initiate slantwise convection thus leading to cloud bands and growth of extratropical cyclones. Also, if the AGWs are ducted to low latitudes, they could influence the development of tropical cyclones. The gravity-wave-induced vertical lift may modulate the slantwise convection by releasing the moist symmetric instability at near-threshold conditions in the warm frontal zone of extratropical cyclones. Latent heat release associated with the mesoscale slantwise convection has been linked to explosive cyclogenesis and severe weather. The circumstantial and statistical evidence of the solar wind influence on extratropical cyclones is further supported by a statistical analysis of high-level clouds (<440 mb extracted from the International Satellite Cloud Climatology Project (ISCCP D1 dataset. A statistically significant response of the high-level cloud area index (HCAI to fast solar wind from coronal holes is found in mid-to-high latitudes during autumn-winter and in low latitudes during spring-summer. In the extratropics, this response of the HCAI to solar wind forcing is consistent with the effect on tropospheric vorticity found by Wilcox et al. (1974 and verified by Prikryl et al. (2009. In the tropics, the observed HCAI response, namely a decrease in HCAI at the arrival of solar wind stream followed by an increase a few days later, is similar to that in the northern and southern mid-to-high latitudes. The amplitude of the response nearly doubles for stream interfaces associated with the interplanetary magnetic field BZ component shifting southward. When the IMF BZ after the stream interface shifts northward, the autumn-winter effect weakens or shifts to lower (mid latitudes

  8. Diffuse Solar System Design and Utilization in Agriculture and ...

    African Journals Online (AJOL)

    Diffuse solar radiation is a component of total solar radiation that is good for low temperature grade heating. Since the portion of the scattered radiation from the sun, which consists of short and long waves, that reaches the earth is diffused, its utilization in Agriculture as this paper suggested, has multiple phase change ...

  9. Energy dissipation of Alfven wave packets deformed by irregular magnetic fields in solar-coronal arches

    Science.gov (United States)

    Similon, Philippe L.; Sudan, R. N.

    1989-01-01

    The importance of field line geometry for shear Alfven wave dissipation in coronal arches is demonstrated. An eikonal formulation makes it possible to account for the complicated magnetic geometry typical in coronal loops. An interpretation of Alfven wave resonance is given in terms of gradient steepening, and dissipation efficiencies are studied for two configurations: the well-known slab model with a straight magnetic field, and a new model with stochastic field lines. It is shown that a large fraction of the Alfven wave energy flux can be effectively dissipated in the corona.

  10. Wave Generation Theory

    DEFF Research Database (Denmark)

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered.......The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered....

  11. Partial Shading Detection in Solar System Using Single Short Pulse of Load

    Directory of Open Access Journals (Sweden)

    Bartczak Mateusz

    2017-03-01

    Full Text Available A single photovoltaic panel under uniform illumination has only one global maximum power point, but the same panel in irregularly illuminated conditions can have more maxima on its power-voltage curve. The irregularly illuminated conditions in most cases are results of partial shading. In the work a single short pulse of load is used to extract information about partial shading. This information can be useful and can help to make some improvements in existing MPPT algorithms. In the paper the intrinsic capacitance of a photovoltaic system is used to retrieve occurrence of partial shading.

  12. 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....

  13. Multi-fluid Modeling of Magnetosonic Wave Propagation in the Solar Chromosphere: Effects of Impact Ionization and Radiative Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Maneva, Yana G.; Laguna, Alejandro Alvarez; Poedts, Stefaan [Department of Mathematics, Center for Mathematical Plasma Astrophysics, Catholic University of Leuven, B-3001 Leuven (Belgium); Lani, Andrea, E-mail: yana.maneva@ws.kuleuven.be, E-mail: stefaan.poedts@wis.kuleuven.be, E-mail: alejandro.alvarez.laguna@vki.ac.be, E-mail: lani@vki.ac.be [von Karman Institute for Fluid Dynamics, CFD group, Aeronautics and Aerospace, Rhode Saint-Genèse (Belgium)

    2017-02-20

    In order to study chromospheric magnetosonic wave propagation including, for the first time, the effects of ion–neutral interactions in the partially ionized solar chromosphere, we have developed a new multi-fluid computational model accounting for ionization and recombination reactions in gravitationally stratified magnetized collisional media. The two-fluid model used in our 2D numerical simulations treats neutrals as a separate fluid and considers charged species (electrons and ions) within the resistive MHD approach with Coulomb collisions and anisotropic heat flux determined by Braginskiis transport coefficients. The electromagnetic fields are evolved according to the full Maxwell equations and the solenoidality of the magnetic field is enforced with a hyperbolic divergence-cleaning scheme. The initial density and temperature profiles are similar to VAL III chromospheric model in which dynamical, thermal, and chemical equilibrium are considered to ensure comparison to existing MHD models and avoid artificial numerical heating. In this initial setup we include simple homogeneous flux tube magnetic field configuration and an external photospheric velocity driver to simulate the propagation of MHD waves in the partially ionized reactive chromosphere. In particular, we investigate the loss of chemical equilibrium and the plasma heating related to the steepening of fast magnetosonic wave fronts in the gravitationally stratified medium.

  14. MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

    International Nuclear Information System (INIS)

    Zhao, Hui; Chou, Dean-Yi

    2016-01-01

    The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ ab and the scattering cross section σ sc for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ ab and σ sc , the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ ab of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ sc of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ ab is approximately proportional to the sunspot radius, while the dependence of σ sc on radius is faster than the linear increase.

  15. MEASUREMENTS OF THE ABSORPTION AND SCATTERING CROSS SECTIONS FOR THE INTERACTION OF SOLAR ACOUSTIC WAVES WITH SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hui [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 200012 (China); Chou, Dean-Yi, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

    2016-05-01

    The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. The absorption cross section and scattering cross section are two important parameters in the scattering problem. In this study, we use the wavefunction of the scattered wave, measured with a deconvolution method, to compute the absorption cross section σ {sub ab} and the scattering cross section σ {sub sc} for the radial order n = 0–5 for two sunspots, NOAA 11084 and NOAA 11092. In the computation of the cross sections, the random noise and dissipation in the measured acoustic power are corrected. For both σ {sub ab} and σ {sub sc}, the value of NOAA 11092 is greater than that of NOAA 11084, but their overall n dependence is similar: decreasing with n . The ratio of σ {sub ab} of NOAA 11092 to that of NOAA 11084 approximately equals the ratio of sunspot radii for all n , while the ratio of σ {sub sc} of the two sunspots is greater than the ratio of sunspot radii and increases with n . This suggests that σ {sub ab} is approximately proportional to the sunspot radius, while the dependence of σ {sub sc} on radius is faster than the linear increase.

  16. Acoustic–gravity waves during solar eclipses: Detection and characterization using wavelet transforms

    Czech Academy of Sciences Publication Activity Database

    Šauli, Petra; Roux, S. G.; Abry, P.; Boška, Josef

    2007-01-01

    Roč. 69, 17-18 (2007), s. 2465-2484 ISSN 1364-6826 R&D Projects: GA ČR GA205/06/1619; GA AV ČR IAA300420504 Grant - others:CNRS(FR) 18098 Institutional research plan: CEZ:AV0Z30420517 Keywords : Acoustic–gravity wave * Vertical ionospheric sounding * F-layer * Wavelet transform * Wave-packet characterization Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.566, year: 2007

  17. HD 140283: A STAR IN THE SOLAR NEIGHBORHOOD THAT FORMED SHORTLY AFTER THE BIG BANG

    Energy Technology Data Exchange (ETDEWEB)

    Bond, Howard E.; Nelan, Edmund P. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); VandenBerg, Don A. [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada); Schaefer, Gail H. [The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Harmer, Dianne, E-mail: bond@stsci.edu, E-mail: nelan@stsci.edu, E-mail: vandenbe@uvic.ca, E-mail: schaefer@chara-array.org, E-mail: diharmer@noao.edu [National Optical Astronomy Observatories, 950 North Cherry Avenue, Tucson, AZ 85726 (United States)

    2013-03-01

    HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the Hertzsprung-Russell diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 {+-} 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 {+-} 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especially the oxygen content, now contribute more to the error budget for the age of HD 140283 than does its distance, increasing the total uncertainty to about {+-}0.8 Gyr. Within the errors, the age of HD 140283 does not conflict with the age of the Universe, 13.77 {+-} 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang.

  18. Beam-plasma interaction in randomly inhomogeneous plasmas and statistical properties of small-amplitude Langmuir waves in the solar wind and electron foreshock

    Czech Academy of Sciences Publication Activity Database

    Krasnoselskikh, V. V.; Lobzin, V. V.; Musatenko, K.; Souček, Jan; Pickett, J. S.; Cairns, I. H.

    2007-01-01

    Roč. 112, A10 (2007), A10109/1-A10109/12 ISSN 0148-0227 R&D Projects: GA AV ČR IAA301120601; GA AV ČR IAA300420602 Institutional research plan: CEZ:AV0Z30420517 Keywords : plasma waves * kinetic waves and instabilities * foreshock * solar wind Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.953, year: 2007

  19. Propagation of large amplitude Alfven waves in the solar wind current sheet

    International Nuclear Information System (INIS)

    Malara, Francesco; Primavera, Leonardo; Veltri, Pierluigi

    1996-01-01

    The time evolution of Alfvenic perturbations in the Solar Wind current sheet is studied by using numerical simulations of the compressible magnetohydrodynamic (MHD) equations. The simulations show that the interaction between the large amplitude Alfvenic pertubation and the solar wind current sheet decreases the correlation between velocity and magnetic field fluctuations and produces compressive fluctuations. The characteristics of these compressive fluctuations compare rather well with spatial observations. The behavior of the correlation between density and magnetic field intensity fluctuations and of the their spectra are well reproduced so that the physical mechanisms giving rise to these behaviors can be identified

  20. HD 140283: A Star in the Solar Neighborhood that Formed Shortly after the Big Bang

    Science.gov (United States)

    Bond, Howard E.; Nelan, Edmund P.; VandenBerg, Don A.; Schaefer, Gail H.; Harmer, Dianne

    2013-03-01

    HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the Hertzsprung-Russell diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 ± 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 ± 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especially the oxygen content, now contribute more to the error budget for the age of HD 140283 than does its distance, increasing the total uncertainty to about ±0.8 Gyr. Within the errors, the age of HD 140283 does not conflict with the age of the Universe, 13.77 ± 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained by the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  1. Very short-term reactive forecasting of the solar ultraviolet index using an extreme learning machine integrated with the solar zenith angle.

    Science.gov (United States)

    Deo, Ravinesh C; Downs, Nathan; Parisi, Alfio V; Adamowski, Jan F; Quilty, John M

    2017-05-01

    Exposure to erythemally-effective solar ultraviolet radiation (UVR) that contributes to malignant keratinocyte cancers and associated health-risk is best mitigated through innovative decision-support systems, with global solar UV index (UVI) forecast necessary to inform real-time sun-protection behaviour recommendations. It follows that the UVI forecasting models are useful tools for such decision-making. In this study, a model for computationally-efficient data-driven forecasting of diffuse and global very short-term reactive (VSTR) (10-min lead-time) UVI, enhanced by drawing on the solar zenith angle (θ s ) data, was developed using an extreme learning machine (ELM) algorithm. An ELM algorithm typically serves to address complex and ill-defined forecasting problems. UV spectroradiometer situated in Toowoomba, Australia measured daily cycles (0500-1700h) of UVI over the austral summer period. After trialling activations functions based on sine, hard limit, logarithmic and tangent sigmoid and triangular and radial basis networks for best results, an optimal ELM architecture utilising logarithmic sigmoid equation in hidden layer, with lagged combinations of θ s as the predictor data was developed. ELM's performance was evaluated using statistical metrics: correlation coefficient (r), Willmott's Index (WI), Nash-Sutcliffe efficiency coefficient (E NS ), root mean square error (RMSE), and mean absolute error (MAE) between observed and forecasted UVI. Using these metrics, the ELM model's performance was compared to that of existing methods: multivariate adaptive regression spline (MARS), M5 Model Tree, and a semi-empirical (Pro6UV) clear sky model. Based on RMSE and MAE values, the ELM model (0.255, 0.346, respectively) outperformed the MARS (0.310, 0.438) and M5 Model Tree (0.346, 0.466) models. Concurring with these metrics, the Willmott's Index for the ELM, MARS and M5 Model Tree models were 0.966, 0.942 and 0.934, respectively. About 57% of the ELM model

  2. Solar Flare Five-Day Predictions from Quantum Detectors of Dynamical Space Fractal Flow Turbulence: Gravitational Wave Diminution and Earth Climate Cooling

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2014-10-01

    Full Text Available Space speed fluctuations, which have a 1 / f spectrum, are shown to be the cause of solar flares. The direction and magnitude of the space flow has been detected from numer- ous different experimental techniques, and is close to the normal to the plane of the ecliptic. Zener diode data shows that the fluctuations in the space speed closely match the Sun Solar Cycle 23 flare count, and reveal that major solar flares follow major space speed fluctuations by some 6 days. This implies that a warning period of some 5 days in predicting major solar flares is possible using such detectors. This has significant conse- quences in being able to protect various spacecraft and Earth located electrical systems from the subsequent arrival of ejected plasma from a solar flare. These space speed fluctuations are the actual gravitational waves, and have a significant magnitude. This discovery is a significant application of the dynamical space phenomenon and theory. We also show that space flow turbulence impacts on the Earth’s climate, as such tur- bulence can input energy into systems, which is the basis of the Zener Diode Quantum Detector. Large scale space fluctuations impact on both the sun and the Earth, and as well explain temperature correlations with solar activity, but that the Earth temperatures are not caused by such solar activity. This implies that the Earth climate debate has been missing a key physical process. Observed diminishing gravitational waves imply a cooling epoch for the Earth for the next 30 years.

  3. Observations of polar patches generated by solar wind Alfvén wave coupling to the dayside magnetosphere

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    1999-04-01

    Full Text Available A long series of polar patches was observed by ionosondes and an all-sky imager during a disturbed period (Kp = 7- and IMF Bz < 0. The ionosondes measured electron densities of up to 9 × 1011 m-3 in the patch center, an increase above the density minimum between patches by a factor of \\sim4.5. Bands of F-region irregularities generated at the equatorward edge of the patches were tracked by HF radars. The backscatter bands were swept northward and eastward across the polar cap in a fan-like formation as the afternoon convection cell expanded due to the IMF By > 0. Near the north magnetic pole, an all-sky imager observed the 630-nm emission patches of a distinctly band-like shape drifting northeastward to eastward. The 630-nm emission patches were associated with the density patches and backscatter bands. The patches originated in, or near, the cusp footprint where they were formed by convection bursts (flow channel events, FCEs structuring the solar EUV-produced photoionization and the particle-produced auroral/cusp ionization by segmenting it into elongated patches. Just equatorward of the cusp footprint Pc5 field line resonances (FLRs were observed by magnetometers, riometers and VHF/HF radars. The AC electric field associated with the FLRs resulted in a poleward-progressing zonal flow pattern and backscatter bands. The VHF radar Doppler spectra indicated the presence of steep electron density gradients which, through the gradient drift instability, can lead to the generation of the ionospheric irregularities found in patches. The FLRs and FCEs were associated with poleward-progressing DPY currents (Hall currents modulated by the IMF By and riometer absorption enhancements. The temporal and spatial characteristics of the VHF backscatter and associated riometer absorptions closely resembled those of poleward moving auroral forms (PMAFs. In the solar wind, IMP 8 observed large amplitude Alfvén waves that were correlated with Pc5 pulsations

  4. Coronal mass ejection kinematics deduced from white light (Solar Mass Ejection Imager) and radio (Wind/WAVES) observations

    Science.gov (United States)

    Reiner, M. J.; Jackson, B. V.; Webb, D. F.; Mizuno, D. R.; Kaiser, M. L.; Bougeret, J.-L.

    2005-09-01

    White-light and radio observations are combined to deduce the coronal and interplanetary kinematics of a fast coronal mass ejection (CME) that was ejected from the Sun at about 1700 UT on 2 November 2003. The CME, which was associated with an X8.3 solar flare from W56°, was observed by the Mauna Loa and Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronograph (LASCO) coronagraphs to 14 R⊙. The measured plane-of-sky speed of the LASCO CME was 2600 km s-1. To deduce the kinematics of this CME, we use the plane-of-sky white light observations from both the Solar Mass Ejection Imager (SMEI) all-sky camera on board the Coriolis spacecraft and the SOHO/LASCO coronagraph, as well as the frequency drift rate of the low-frequency radio data and the results of the radio direction-finding analysis from the WAVES experiment on the Wind spacecraft. In agreement with the in situ observations for this event, we find that both the white light and radio observations indicate that the CME must have decelerated significantly beginning near the Sun and continuing well into the interplanetary medium. More specifically, by requiring self-consistency of all the available remote and in situ data, together with a simple, but not unreasonable, assumption about the general characteristic of the CME deceleration, we were able to deduce the radial speed and distance time profiles for this CME as it propagated from the Sun to 1 AU. The technique presented here, which is applicable to mutual SMEI/WAVES CME events, is expected to provide a more complete description and better quantitative understanding of how CMEs propagate through interplanetary space, as well as how the radio emissions, generated by propagating CME/shocks, relate to the shock and CME. This understanding can potentially lead to more accurate predictions for the onset times of space weather events, such as those that were observed during this unique period of intense solar activity.

  5. Evaluating the suitability of the SWAN/COSMO-2 model system to simulate short-crested surface waves for a narrow lake with complex bathymetry

    Directory of Open Access Journals (Sweden)

    Michael Graf

    2013-07-01

    Full Text Available The spectral wave model SWAN (Simulating Waves Nearshore was applied to Lake Zurich, a narrow pre-Alpine lake in Switzerland. The aim of the study is to investigate whether the model system consisting of SWAN and the numerical weather prediction model COSMO-2 is a suitable tool for wave forecasts for the pre-Alpine Lake Zurich. SWAN is able to simulate short-crested wind-generated surface waves. The model was forced with a time varying wind field taken from COSMO-2 with hourly outputs. Model simulations were compared with measured wave data at one near-shore site during a frontal passage associated with strong on-shore winds. The overall course of the measured wave height is well captured in the SWAN simulation: the wave amplitude significantly increases during the frontal passage followed by a transient drop in amplitude. The wave pattern on Lake Zurich is quite complex. It strongly depends on the inherent variability of the wind field and on the external forcing due to the surrounding complex topography. The influence of the temporal wind resolution is further studied with two sensitivity experiments. The first one considers a low-pass filtered wind field, based on a 2-h running mean of COSMO-2 output, and the second experiment uses simple synthetic gusts, which are implemented into the SWAN model and take into account short-term fluctuations of wind speed at 1-sec resolution. The wave field significantly differs for the 1-h and 2-h simulations, but is only negligibly affected by the gusts.

  6. The Distribution of Chorus and Plasmaspheric Hiss Waves in the Inner Magnetospahere as Functions of Geomagnetic Activity and Solar Wind Parameters as Observed by The Van Allen Probes.

    Science.gov (United States)

    Aryan, H.; Sibeck, D. G.; Balikhin, M. A.; Agapitov, O. V.; Kletzing, C.

    2015-12-01

    The dynamics of the radiation belts is dependent upon the acceleration and loss of radiation belt electrons that is largely determined by the interaction of georesonant wave particles with chorus and plasmaspheric hiss waves. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity as expressed by the geomagnetic indices (Ae, Kp, and Dst). However, it has been shown that not all geomagnetic storms necessarily increase the flux of energetic electrons at the radiation belts. In fact, almost 20% of all geomagnetic storms cause a decrease in the flux of energetic electrons, while 30% has relatively no effect. Also, the geomagnetic indices are indirect, nonspecific parameters compiled from imperfectly covered ground based measurements that lack time history. This emphasises the need to present wave distributions as a function of both geomagnetic activity and solar wind parameters, such as velocity (V), density (n), and interplanetary magnetic field component (Bz), that are known to be predominantly effective in the control of radiation belt energetic electron fluxes. This study presents the distribution of chorus and plasmaspheric hiss waves in the inner magnetosphere as functions of both geomagnetic activity and solar wind parameters for different L-shell, magnetic local time, and magnetic latitude. This study uses almost three years of data measured by the EMFISIS on board the Van Allen Probes. Initial results indicate that the intensity of chorus and plasmaspheric hiss emissions are not only dependent on the geomagnetic activity but also dependent on solar wind parameters. The largest average wave intensities are observed with equatorial chorus in the region 4solar wind velocity, low solar wind density, and highly negative Bz respectively.

  7. Morphology of low-frequency waves in the solar wind and their relation to ground pulsations

    International Nuclear Information System (INIS)

    Odera, T.J.; Stuart, W.F.

    1986-01-01

    Three classes of low frequency waves (period range 20 to 80 s) were identified using data from the UCLA fluxgate magnetometer experiment on board the ISEE 2 spacecraft. These are continuous pulsations similar in type to Pc 3, band-limited oscillations distinguished by mixed period fluctuations, and relatively isolated wave bundles. The waves were preferentially observed when the interplanetary magnetic field (IMF) direction was sunward and were most common when the cone angle, i.e. the angle between IMF and the Sun-Earth line (thetasub(xB)) was often between 15 deg and 45 deg. Their frequency is proportional to the IMF magnitude. Comparison between the waves observed on board the ISEE 2 spacecraft and the Pc 3-4 recorded simultaneously at a mid-latitude ground station, Oulu (L = 4.5), showed that similarity of spectra of the waves in the spacecraft and on the ground was very rare and that correspondence between the events in space and on the ground was extremely low. (author)

  8. Achieving 12.8% Efficiency by Simultaneously Improving Open-Circuit Voltage and Short-Circuit Current Density in Tandem Organic Solar Cells.

    Science.gov (United States)

    Qin, Yunpeng; Chen, Yu; Cui, Yong; Zhang, Shaoqing; Yao, Huifeng; Huang, Jiang; Li, Wanning; Zheng, Zhong; Hou, Jianhui

    2017-06-01

    Tandem organic solar cells (TOSCs), which integrate multiple organic photovoltaic layers with complementary absorption in series, have been proved to be a strong contender in organic photovoltaic depending on their advantages in harvesting a greater part of the solar spectrum and more efficient photon utilization than traditional single-junction organic solar cells. However, simultaneously improving open circuit voltage (V oc ) and short current density (J sc ) is a still particularly tricky issue for highly efficient TOSCs. In this work, by employing the low-bandgap nonfullerene acceptor, IEICO, into the rear cell to extend absorption, and meanwhile introducing PBDD4T-2F into the front cell for improving V oc , an impressive efficiency of 12.8% has been achieved in well-designed TOSC. This result is also one of the highest efficiencies reported in state-of-the-art organic solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

    OpenAIRE

    Abbott, B. P.; Abbott, R.; Adhikari, R. X.; Anderson, S. B.; Arai, K.; Araya, M. C.; Barayoga, J. C.; Barish, B. C.; Berger, B. K.; Billingsley, G.; Blackburn, J. K.; Bork, R.; Brooks, A. F.; Brunett, S.; Cahillane, C.

    2016-01-01

    We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a signifi...

  10. Study of Green Shipping Technologies - Harnessing Wind, Waves and Solar Power in New Generation Marine Propulsion Systems

    Directory of Open Access Journals (Sweden)

    Grzegorz Rutkowski

    2016-12-01

    Full Text Available The purpose and scope of this paper is to describe the complexity of the new generation marine propulsion technologies implemented in the shipping industry to promote green ships concept and change the view of sea transportation to a more ecological and environment-friendly. Harnessing wind, waves and solar power in shipping industry can help the ship’s owners reduce the operational costs. Reducing fuel consumption results in producing less emissions and provides a clean source of renewable energy. Green shipping technologies can also effectively increase the operating range of vessels and help drive sea transportation towards a greener future and contribute to the global reduction of harmful gas emissions from the world's shipping fleets.

  11. A low cost short wave near infrared spectrophotometer: application for determination of quality parameters of diesel fuel.

    Science.gov (United States)

    Gonzaga, Fabiano Barbieri; Pasquini, Celio

    2010-06-18

    A low cost absorption spectrophotometer for the short wave near infrared spectral region (850-1050 nm) is described. The spectrophotometer is basically composed of a conventional dichroic lamp, a long-pass filter, a sample cell and a Czerny-Turner type polychromator coupled to a 1024 pixel non-cooled photodiode array. A preliminary evaluation of the spectrophotometer showed good repeatability of the first derivative of the spectra at a constant room temperature and the possibility of assigning some spectral regions to different C-H stretching third overtones. Finally, the spectrophotometer was successfully applied for the analysis of diesel samples and the determination of some of their quality parameters using partial least squares calibration models. The values found for the root mean square error of prediction using external validation were 0.5 for the cetane index and from 2.5 to 5.0 degrees C for the temperatures achieved during distillation when obtaining 10, 50, 85, and 90% (v/v) of the distilled sample, respectively. 2010 Elsevier B.V. All rights reserved.

  12. InGaAs/GaAsSb Type-II superlattice based photodiodes for short wave infrared detection

    Science.gov (United States)

    Uliel, Y.; Cohen-Elias, D.; Sicron, N.; Grimberg, I.; Snapi, N.; Paltiel, Y.; Katz, M.

    2017-08-01

    Short Wave Infra-Red (SWIR) photodetectors operating above the response cutoff of InGaAs- based detectors (1.7-2.5 μm) are required for both defense and civil applications. Type II Super-Lattices (T2SL) were recently proposed For near- room temperature SWIR detection as a possible system enabling bandgap adjustment in the required range. The work presented here focuses on a T2SL with alternating nano-layers of InGaAs and GaAsSb lattice-matched to an InP substrate. A near room temperature SWIR cutoff of 2.4 μm was measured. Electrical junctions were realized using Zn diffusion p-doping process. We realized and studied both mesa- and selective diffusion- based p-i-n photodiodes. Dark currents of mesa-based devices were 1.5 mA/cm2 and 32 μA/cm2 at 300 and 230 K respectively. Dark currents were reduced to 1.2 mA/cm2 and 12 μA/cm2 respectively by utilizing the selective diffusion process. The effect of operating voltage is discussed. At 300 K the quantum efficiency was up to 40% at 2.18 μm in mesa devices. D∗ was 1.7 ×1010cm ·√{Hz } /W at 2 μm.

  13. Infrared autofluorescence, short-wave autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytomas

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2016-05-01

    Full Text Available AIM: To investigate the findings of infrared fundus autofluorescence (IR-AF and spectral-domain optical coherence tomography (SD-OCT in eyes with optic disc melanocytoma (ODM. METHODS: IR-AF findings and those of other ophthalmologic imaging examinations, including short-wave autofluorescence (SW-AF, fluorescein angiography (FA, fundus color photography, and SD-OCT of 8 eyes of 8 consecutive cases with ODM were assessed. RESULTS: The ODMs in all cases (100% presented similar IR-AF, SW-AF, and FA findings. On IR-AF images, ODMs showed outstanding hyper-AF with well-defined outline. On SW-AF images, the area of ODMs presented as hypo-AF. FA images revealed the leaking retinal telangiectasia on the surface of the ODMs. On SD-OCT images in 8 cases (100%, the ODMs were sloped with highly reflective surface, which were disorganized retina and optic nerve layers. In 7 cases (87.5%, peripapillary choroids were involved. The melanocytomas of 8 cases (100% presented as optically empty spaces. Vitreous seeds were found in one case (12.5%. CONCLUSION: IR-AF imaging may provide a new modality to evaluate the pathologic features of ODMs, and together with SW-AF imaging, offers a new tool to study biological characteristics associated with ODMs. SD-OCT is a valuable tool in delimitating the tumor extension and providing morphological information about the adjacent retinal tissue.

  14. Does variation in mineral composition alter the short-wave light scattering properties of desert dust aerosol?

    International Nuclear Information System (INIS)

    Smith, Andrew J.A.; Grainger, Roy G.

    2014-01-01

    Mineral dust aerosol is a major component of natural airborne particulates. Using satellite measurements from the visible and near-infrared, there is insufficient information to retrieve a full microphysical and chemical description of an aerosol distribution. As such, refractive index is one of many parameters that must be implicitly assumed in order to obtain an optical depth retrieval. This is essentially a proxy for the dust mineralogy. Using a global soil map, it is shown that as long as a reasonable refractive index for dust is assumed, global dust variability is unlikely to cause significant variation in the optical properties of a dust aerosol distribution in the short-wave, and so should not greatly affect retrievals of mineral dust aerosol from space by visible and near-infrared radiometers. Errors in aerosol optical depth due to this variation are expected to be ≲1%. The work is framed around the ORAC AATSR aerosol retrieval, but is equally applicable to similar satellite retrievals. In this case, variations in the top-of-atmosphere reflectance caused by mineral variation are within the noise limits of the instrument. -- Highlights: • Global variation in dust aerosol refractive index is quantified using soil maps. • Resulting visible light scattering properties have limited variability. • Satellite aerosol retrievals do not need to account for varying dust refractive indices

  15. The Heating of Solar Coronal Loops by Alfvén Wave Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Van Ballegooijen, A. A. [5001 Riverwood Avenue, Sarasota, FL 34231 (United States); Asgari-Targhi, M.; Voss, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-11-01

    In this paper we further develop a model for the heating of coronal loops by Alfvén wave turbulence (AWT). The Alfvén waves are assumed to be launched from a collection of kilogauss flux tubes in the photosphere at the two ends of the loop. Using a three-dimensional magnetohydrodynamic model for an active-region loop, we investigate how the waves from neighboring flux tubes interact in the chromosphere and corona. For a particular combination of model parameters we find that AWT can produce enough heat to maintain a peak temperature of about 2.5 MK, somewhat lower than the temperatures of 3–4 MK observed in the cores of active regions. The heating rates vary strongly in space and time, but the simulated heating events have durations less than 1 minute and are unlikely to reproduce the observed broad differential emission measure distributions of active regions. The simulated spectral line nonthermal widths are predicted to be about 27 km s{sup −1}, which is high compared to the observed values. Therefore, the present AWT model does not satisfy the observational constraints. An alternative “magnetic braiding” model is considered in which the coronal field lines are subject to slow random footpoint motions, but we find that such long-period motions produce much less heating than the shorter-period waves launched within the flux tubes. We discuss several possibilities for resolving the problem of producing sufficiently hot loops in active regions.

  16. Spectroscopic Evidence of Alfvén Wave Damping in the Off-limb Solar Corona

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, G. R., E-mail: girjesh@iucaa.in [Inter-University Centre for Astronomy and Astrophysics, Post Bag-4, Ganeshkhind, Pune 411007 (India)

    2017-02-10

    We investigate the off-limb active-region and quiet-Sun corona using spectroscopic data. The active region is clearly visible in several spectral lines formed in the temperature range of 1.1–2.8 MK. We derive the electron number density using the line ratio method, and the nonthermal velocity in the off-limb region up to the distance of 140 Mm. We compare density scale heights derived from several spectral line pairs with expected scale heights per the hydrostatic equilibrium model. Using several isolated and unblended spectral line profiles, we estimate nonthermal velocities in the active region and quiet Sun. Nonthermal velocities obtained from warm lines in the active region first show an increase and then later either a decrease or remain almost constant with height in the far off-limb region, whereas nonthermal velocities obtained from hot lines show consistent decrease. However, in the quiet-Sun region, nonthermal velocities obtained from various spectral lines show either a gradual decrease or remain almost constant with height. Using these obtained parameters, we further calculate Alfvén wave energy flux in both active and quiet-Sun regions. We find a significant decrease in wave energy fluxes with height, and hence provide evidence of Alfvén wave damping. Furthermore, we derive damping lengths of Alfvén waves in the both regions and find them to be in the range of 25–170 Mm. Different damping lengths obtained at different temperatures may be explained as either possible temperature-dependent damping or by measurements obtained in different coronal structures formed at different temperatures along the line of sight. Temperature-dependent damping may suggest some role of thermal conduction in the damping of Alfvén waves in the lower corona.

  17. Radio Spectral Imaging of Reflective MHD Waves during the Impulsive Phase of a Solar Flare

    Science.gov (United States)

    Yu, S.; Chen, B.; Reeves, K.

    2017-12-01

    We report a new type of coherent radio bursts observed by the Karl G. Jansky Very Large Array (VLA) in 1-2 GHz during the impulsive phase of a two-ribbon flare on 2014 November 1, which we interpret as MHD waves reflected near the footpoint of flaring loops. In the dynamic spectrum, this burst starts with a positive frequency drift toward higher frequencies until it slows down near its highest-frequency boundary. Then it turns over and drifts toward lower frequencies. The frequency drift rate in its descending and ascending branch is between 50-150 MHz/s, which is much slower than type III radio bursts associated with fast electron beams but close to the well-known intermediate drift bursts, or fiber bursts, which are usually attributed to propagating whistler or Alfvenic waves. Thanks to VLA's unique capability of imaging with spectrometer-like temporal and spectral resolution (50 ms and 2 MHz), we are able to obtain an image of the radio source at every time and frequency in the dynamic spectrum where the burst is present and trace its spatial evolution. From the imaging results, we find that the radio source firstly moves downward toward one of the flaring ribbons before it "bounces off" at the lowest height (corresponding to the turnover frequency in the dynamic spectrum) and moves upward again. The measured speed in projection is at the order of 1-2 Mm/s, which is characteristic of Alfvenic or fast-mode MHD waves in the low corona. We conclude that the radio burst is emitted by trapped nonthermal electrons in the flaring loop carried along by a large-scale MHD wave. The waves are probably launched during the eruption of a magnetic flux rope in the flare impulsive phase.

  18. Regulation of ion drifts and anisotropies by parametrically unstable finite-amplitude Alfvén-cyclotron waves in the fast solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Maneva, Y. G. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Araneda, J. A. [Departamento de Física, Universidad de Concepción, 4070386 (Chile); Marsch, E., E-mail: yana.g.maneva@nasa.gov [Institute for Experimental and Applied Physics, Christian Albrechts University at Kiel, D-24118 Kiel (Germany)

    2014-03-10

    We study the preferential heating and differential acceleration of minor ions by dissipation of ion-acoustic waves (IAWs) generated by parametric instabilities of a finite-amplitude monochromatic Alfvén-cyclotron pump wave. We consider the associated kinetic effects of Landau damping and nonlinear pitch-angle scattering of protons and α particles in the tenuous plasma of coronal holes and the fast solar wind. Various data collected by Wind spacecraft show signatures for a local transverse heating of the minor ions, presumably by Alfvén-cyclotron wave dissipation, and an unexpected parallel heating by a so far unknown mechanism. Here, we present the results from a set of 1.5 dimensional hybrid simulations in search for a plausible explanation for the observed field-aligned kinetic features in the fast solar wind minor ions. We investigate the origin and regulation of ion relative drifts and temperature anisotropies in low plasma β, fast solar wind conditions. Depending on their initial drifts, both ion species can heat up not only transversely through cyclotron resonance and non-resonant wave-particle interactions, but also strongly in the parallel direction by Landau damping of the daughter IAWs. We discuss the dependence of the relative ion drifts and temperature anisotropies on the plasma β of the individual species and we describe the effect of the pump wave amplitude on the ion heating and acceleration.

  19. Neutron-captures in Low Mass Stars and the Early Solar System Record of Short-lived Radioactivities

    Science.gov (United States)

    Busso, Maurizio; Vescovi, Diego; Trippella, Oscar; Palmerini, Sara; Cristallo, Sergio; Piersanti, Luciano

    2018-01-01

    Noticeable improvements were recently introduced in the modelling of n-capture nucleosynthesis in the advanced evolutionary stages of giant stars (Asymptotic Giant Branch, or AGB, stars). Two such improvements are closely linked together and concern the introduction of non-parameterized, physical models for extended mixing processes and the adoption of accurate reaction rates for H- and He-burning reactions, including the one for the main neutron source 13C(α,n)16O. These improvements profited of a longstanding collaboration between stellar physicists and C. Spitaleri's team and of his seminal work both as a leader in the Nuclear Astrophysics scenario and as a talent-scout in the recruitment of young researchers in the field. We present an example of the innovative results that can be obtained thanks to the novelties introduced, by estimating the contributions from a nearby AGB star to the synthesis of short-lived (t1/2 ≤ 10 Myr) radioactive nuclei which were alive in early Solar System condensates. We find that the scenario indicating an AGB star as the source of such radioactivities, discussed for many years by researchers in this field, appears now to be no longer viable, when the mentioned improvements of AGB models and nuclear parameters are considered.

  20. Simultaneous improvement in short circuit current, open circuit voltage, and fill factor of polymer solar cells through ternary strategy.

    Science.gov (United States)

    An, Qiaoshi; Zhang, Fujun; Li, Lingliang; Wang, Jian; Sun, Qianqian; Zhang, Jian; Tang, Weihua; Deng, Zhenbo

    2015-02-18

    We present a smart strategy to simultaneously increase the short circuit current (Jsc), the open circuit voltage (Voc), and the fill factor (FF) of polymer solar cells (PSCs). A two-dimensional conjugated small molecule photovoltaic material (SMPV1), as the second electron donor, was doped into the blend system of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl (PC71BM) to form ternary PSCs. The ternary PSCs with 5 wt % SMPV1 doping ratio in donors achieve 4.06% champion power conversion efficiency (PCE), corresponding to about 21.2% enhancement compared with the 3.35% PCE of P3HT:PC71BM-based PSCs. The underlying mechanism on performance improvement of ternary PSCs can be summarized as (i) harvesting more photons in the longer wavelength region to increase Jsc; (ii) obtaining the lower mixed highest occupied molecular orbital (HOMO) energy level by incorporating SMPV1 to increase Voc; (iii) forming the better charge carrier transport channels through the cascade energy level structure and optimizing phase separation of donor/acceptor materials to increase Jsc and FF.

  1. Solar Features - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the...

  2. MAGNETIC-RECONNECTION GENERATED SHOCK WAVES AS A DRIVER OF SOLAR SURGES

    International Nuclear Information System (INIS)

    Yang, Heesu; Chae, Jongchul; Park, Hyungmin; Song, Dong-uk; Cho, Kyuhyoun; Lim, Eun-Kyung; Lee, Kyoung-sun

    2014-01-01

    We found that a surge consists of multiple shock features. In our high-spatiotemporal spectroscopic observation of the surge, each shock is identified with the sudden appearance of an absorption feature at the blue wings of the Ca II 8542 Å line and Hα line that gradually shifts to the red wings. The shock features overlap with one another with the time interval of 110 s, which is much shorter than the duration of each shock feature, 300-400 s. This finding suggests that the multiple shocks might not have originated from a train of sinusoidal waves generated by oscillations and flows in the photosphere. As we found the signature of the magnetic flux cancelations at the base of the surge, we conclude that the multiple shock waves in charge of the surge were generated by the magnetic reconnection that occurred in the low atmosphere in association with the flux cancelation

  3. GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Camp, Jordan B.; hide

    2016-01-01

    We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5(sigma). The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4(+0.7/-0.9) x 10(exp -22). The inferred source-frame initial black hole masses are 14.2(+8.3/-3.7 Stellar Mass and 7.5(+2.3/-2.3) Stellar Mass, and the final black hole mass is 20.8(+6.1/-1.7) Stellar Mass. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440(+180/-190) Mpc corresponding to a redshift of 0.090(+.030/-0.04). All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

  4. GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Bejger, M.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; De, S.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devine, R. C.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Fenyvesi, E.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fong, H.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Geng, P.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hamilton, H.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jian, L.; Jiménez-Forteza, F.; Johnson, W. W.; Johnson-McDaniel, N. K.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chi-Woong; Kim, Chunglee; Kim, J.; Kim, K.; Kim, N.; Kim, W.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kissel, J. S.; Klein, B.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Lewis, J. B.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Lombardi, A. L.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, A.; Miller, B. B.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Nedkova, K.; Nelemans, G.; Nelson, T. J. N.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Ricci, F.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Setyawati, Y.; Shaddock, D. A.; Shaffer, T.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stevenson, S. P.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tomlinson, C.; Tonelli, M.; Tornasi, Z.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Worden, J.; Wright, J. L.; Wu, D. S.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yu, H.; Yvert, M.; Zadrożny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Boyle, M.; Hemberger, D.; Kidder, L. E.; Lovelace, G.; Ossokine, S.; Scheel, M.; Szilagyi, B.; Teukolsky, S.; LIGO Scientific Collaboration; VIRGO Collaboration

    2016-06-01

    We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5 σ . The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3. 4-0.9+0.7×10-22 . The inferred source-frame initial black hole masses are 14.2-3.7+8.3 M⊙ and 7. 5-2.3+2.3 M⊙, and the final black hole mass is 20.8-1.7+6.1 M⊙. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 44 0-190+180 Mpc corresponding to a redshift of 0.0 9-0.04+0.03. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

  5. DO OBLIQUE ALFVÉN/ION-CYCLOTRON OR FAST-MODE/WHISTLER WAVES DOMINATE THE DISSIPATION OF SOLAR WIND TURBULENCE NEAR THE PROTON INERTIAL LENGTH?

    International Nuclear Information System (INIS)

    He Jiansen; Tu Chuanyi; Marsch, Eckart; Yao Shuo

    2012-01-01

    To determine the wave modes prevailing in solar wind turbulence at kinetic scales, we study the magnetic polarization of small-scale fluctuations in the plane perpendicular to the data sampling direction (namely, the solar wind flow direction, V SW ) and analyze its orientation with respect to the local background magnetic field B 0,local . As an example, we take only measurements made in an outward magnetic sector. When B 0,local is quasi-perpendicular to V SW , we find that the small-scale magnetic-field fluctuations, which have periods from about 1 to 3 s and are extracted from a wavelet decomposition of the original time series, show a polarization ellipse with right-handed orientation. This is consistent with a positive reduced magnetic helicity, as previously reported. Moreover, for the first time we find that the major axis of the ellipse is perpendicular to B 0,local , a property that is characteristic of an oblique Alfvén wave rather than oblique whistler wave. For an oblique whistler wave, the major axis of the magnetic ellipse is expected to be aligned with B 0,local , thus indicating significant magnetic compressibility, and the polarization turns from right to left handedness as the wave propagation angle (θ kB ) increases toward 90°. Therefore, we conclude that the observation of a right-handed polarization ellipse with orientation perpendicular to B 0,local seems to indicate that oblique Alfvén/ion-cyclotron waves rather than oblique fast-mode/whistler waves dominate in the 'dissipation' range near the break of solar wind turbulence spectra occurring around the proton inertial length.

  6. An evaluation of safety guidelines to restrict exposure to stray radiofrequency radiation from short-wave diathermy units

    Energy Technology Data Exchange (ETDEWEB)

    Shields, Nora [School of Physiotherapy, La Trobe University, Victoria 3086 (Australia); O' Hare, Neil [Department of Medical Physics and Bioengineering, St James' s Hospital, Dublin 8 (Ireland); Gormley, John [School of Physiotherapy, Trinity College Dublin, Trinity Centre for Health Sciences, St James' s Hospital, Dublin 8 (Ireland)

    2004-07-07

    Short-wave diathermy (SWD), a form of radiofrequency radiation used therapeutically by physiotherapists, may be applied in continuous (CSWD) or pulsed (PSWD) mode using either capacitive or inductive methods. Stray radiation emitted by these units may exceed exposure guidelines close to the equipment. Discrepant guidelines exist on a safe distance from an operating unit for operators and other personnel. Stray electric (E-field) and magnetic (H-field) field strengths from 10 SWD units in six departments were examined using a PMM 8053 meter and two isotropic probes (EP-330, HP-032). A 5 l saline phantom completed the patient circuit. Measurements were recorded in eight directions between 0.5 m and 2 m at hip and eye levels while the units operated at maximum output and data compared to current guidelines. Results found stray fields from capacitive CSWD fell below operator limits at 2 m (E-field 4.8-39.8 V/m; H-field 0.015-0.072 A/m) and at 1 m for inductive CSWD (E-field 0-36 V/m; H-field 0.01-0.065 A/m). Capacitive PSWD fields fell below the limits at 1.5 m (E-field 1.2-19.9 V/m; H-field 0.002-0.045 A/m) and at 1m for inductive PSWD (E-field 0.7-4.0 V/m; H-field 0.009-0.03 A/m). An extra 0.5 m was required before fields fell below the guidelines for other personnel. These results demonstrate, under a worst case scenario, emissions from SWD exceed the guidelines for operators at distances currently recommended as safe. Future guidelines should include recommendations for personnel other than physiotherapists.

  7. An evaluation of safety guidelines to restrict exposure to stray radiofrequency radiation from short-wave diathermy units

    International Nuclear Information System (INIS)

    Shields, Nora; O'Hare, Neil; Gormley, John

    2004-01-01

    Short-wave diathermy (SWD), a form of radiofrequency radiation used therapeutically by physiotherapists, may be applied in continuous (CSWD) or pulsed (PSWD) mode using either capacitive or inductive methods. Stray radiation emitted by these units may exceed exposure guidelines close to the equipment. Discrepant guidelines exist on a safe distance from an operating unit for operators and other personnel. Stray electric (E-field) and magnetic (H-field) field strengths from 10 SWD units in six departments were examined using a PMM 8053 meter and two isotropic probes (EP-330, HP-032). A 5 l saline phantom completed the patient circuit. Measurements were recorded in eight directions between 0.5 m and 2 m at hip and eye levels while the units operated at maximum output and data compared to current guidelines. Results found stray fields from capacitive CSWD fell below operator limits at 2 m (E-field 4.8-39.8 V/m; H-field 0.015-0.072 A/m) and at 1 m for inductive CSWD (E-field 0-36 V/m; H-field 0.01-0.065 A/m). Capacitive PSWD fields fell below the limits at 1.5 m (E-field 1.2-19.9 V/m; H-field 0.002-0.045 A/m) and at 1m for inductive PSWD (E-field 0.7-4.0 V/m; H-field 0.009-0.03 A/m). An extra 0.5 m was required before fields fell below the guidelines for other personnel. These results demonstrate, under a worst case scenario, emissions from SWD exceed the guidelines for operators at distances currently recommended as safe. Future guidelines should include recommendations for personnel other than physiotherapists

  8. On statistical properties of wave amplitudes in stormy sea. Effect of short-crestedness; Daihakoji no haro no tokeiteki seishitsu ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimoto, H. [Ship Research Inst., Tokyo (Japan)

    1996-12-31

    Since ocean waves encountered by ocean vessels or offshore structures in actual sea areas present extremely irregular variations, a stochastic method is necessary to estimate their statistical properties. This paper first shows a calculation method for probability density function for water level variation which strictly incorporates a secondary non-linear effect containing directional dispersibility by modeling ocean waves as short-crested irregular waves. Then, the paper specifically elucidates effects of the directional dispersibility of ocean waves on statistical amount of amplitudes by deriving the statistical amount of the amplitudes based on the probability density function of the water level variation and by using a numerical simulation. The paper finally takes up data of waves in stormy sea observed in an experiment in an actual sea area, compares the result with that of theoretical calculations, and evaluates reasonability of this method. With this estimation method, individual secondary components or components of difference and sum may be subjected to influence of the directional dispersibility, but they do not differ much from the case of long-crested irregular waves on the whole. 21 refs., 11 figs., 2 tabs.

  9. GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence.

    Science.gov (United States)

    Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Bejger, M; Bell, A S; Berger, B K; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Birnholtz, O; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Boer, M; Bogaert, G; Bogan, C; Bohe, A; Bond, C; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Broida, J E; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Brunett, S; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cabero, M; Cadonati, L; Cagnoli, G; Cahillane, C; Calderón Bustillo, J; Callister, T; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Casanueva Diaz, J; Casentini, C; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Cerboni Baiardi, L; Cerretani, G; Cesarini, E; Chamberlin, S J; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Cheeseboro, B D; Chen, H Y; Chen, Y; Cheng, C; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P-F; Colla, A; Collette, C G; Cominsky, L; Constancio, M; Conte, A; Conti, L; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J-P; Countryman, S T; Couvares, P; Cowan, E E; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dal Canton, T; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Dasgupta, A; Da Silva Costa, C F; Dattilo, V; Dave, I; Davier, M; Davies, G S; Daw, E J; Day, R; De, S; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Devine, R C; Dhurandhar, S; Díaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Virgilio, A; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Ducrot, M; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H-B; Ehrens, P; Eichholz, J; Eikenberry, S S; Engels, W; Essick, R C; Etzel, T; Evans, M; Evans, T M; Everett, R; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Fenyvesi, E; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fong, H; Fournier, J-D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H A G; Gair, J R; Gammaitoni, L; Gaonkar, S G; Garufi, F; Gaur, G; Gehrels, N; Gemme, G; Geng, P; Genin, E; Gennai, A; George, J; Gergely, L; Germain, V; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Goetz, E; Goetz, R; Gondan, L; González, G; Gonzalez Castro, J M; Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hacker, J J; Hall, B R; Hall, E D; Hamilton, H; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C-J; Haughian, K; Healy, J; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Henry, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hofman, D; Holt, K; Holz, D E; Hopkins, P; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J-M; Isi, M; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jian, L; Jiménez-Forteza, F; Johnson, W W; Johnson-McDaniel, N K; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kapadia, S J; Karki, S; Karvinen, K S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; Kéfélian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chi-Woong; Kim, Chunglee; Kim, J; Kim, K; Kim, N; Kim, W; Kim, Y-M; Kimbrell, S J; King, E J; King, P J; Kissel, J S; Klein, B; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Krueger, C; Kuehn, G; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Laxen, M; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levin, Y; Lewis, J B; Li, T G F; Libson, A; Littenberg, T B; Lockerbie, N A; Lombardi, A L; London, L T; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lousto, C O; Lück, H; Lundgren, A P; Lynch, R; Ma, Y; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magaña Zertuche, L; Magee, R M; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Mandel, I; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matichard, F; Matone, L; Mavalvala, N; Mazumder, N; McCarthy, R; McClelland, D E; McCormick, S; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McRae, T; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Melatos, A; Mendell, G; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, A; Miller, B B; Miller, J; Millhouse, M; Minenkov, Y; Ming, J; Mirshekari, S; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, N; Mullavey, A; Munch, J; Murphy, D J; Murray, P G; Mytidis, A; Nardecchia, I; Naticchioni, L; Nayak, R K; Nedkova, K; Nelemans, G; Nelson, T J N; Neri, M; Neunzert, A; Newton, G; Nguyen, T T; Nielsen, A B; Nissanke, S; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; O'Shaughnessy, R; Ottaway, D J; Overmier, H; Owen, B J; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Perreca, A; Perri, L M; Pfeiffer, H P; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Poe, M; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prix, R; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qi, H; Qin, J; Qiu, S; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rajan, C; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Reyes, S D; Ricci, F; Riles, K; Rizzo, M; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Sakellariadou, M; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O E S; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Schönbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Setyawati, Y; Shaddock, D A; Shaffer, T; Shahriar, M S; Shaltev, M; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stevenson, S P; Stone, R; Strain, K A; Straniero, N; Stratta, G; Strauss, N A; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sunil, S; Sutton, P J; Swinkels, B L; Szczepańczyk, M J; Tacca, M; Talukder, D; Tanner, D B; Tápai, M; Tarabrin, S P; Taracchini, A; Taylor, R; Theeg, T; Thirugnanasambandam, M P; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Toland, K; Tomlinson, C; Tonelli, M; Tornasi, Z; Torres, C V; Torrie, C I; Töyrä, D; Travasso, F; Traylor, G; Trifirò, D; Tringali, M C; Trozzo, L; Tse, M; Turconi, M; Tuyenbayev, D; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Bakel, N; van Beuzekom, M; van den Brand, J F J; Van Den Broeck, C; Vander-Hyde, D C; van der Schaaf, L; van Heijningen, J V; van Veggel, A A; Vardaro, M; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vinciguerra, S; Vine, D J; Vinet, J-Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, R L; Warner, J; Was, M; Weaver, B; Wei, L-W; Weinert, M; Weinstein, A J; Weiss, R; Wen, L; Weßels, P; Westphal, T; Wette, K; Whelan, J T; Whiting, B F; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Woehler, J; Worden, J; Wright, J L; Wu, D S; Wu, G; Yablon, J; Yam, W; Yamamoto, H; Yancey, C C; Yu, H; Yvert, M; Zadrożny, A; Zangrando, L; Zanolin, M; Zendri, J-P; Zevin, M; Zhang, L; Zhang, M; Zhang, Y; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zucker, M E; Zuraw, S E; Zweizig, J; Boyle, M; Hemberger, D; Kidder, L E; Lovelace, G; Ossokine, S; Scheel, M; Szilagyi, B; Teukolsky, S

    2016-06-17

    We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

  10. Radio wave scattering observations of the solar corona: First-order measurements of expansion velocity and turbulence spectrum using Viking and Mariner 10 spacecraft

    International Nuclear Information System (INIS)

    Tyler, G.L.; Vesecky, J.F.; Plume, M.A.; Howard, H.T.; Barnes, A.

    1981-01-01

    Solar conjunction of Mars on 1976 November 25 occurred very near the beginning of solar cycle 21, about 4 months after the first Viking spacecraft arrived at the planet. Radio wave scattering data were collected at 3.6 and 13 cm wavelengths, using the radio link between the Viking orbiters and the Earth. These data allow measurements of solar wind properties over a range of heliocentric radial distance from approx.6 to 44 R/sub sun/ with solar latitudes ranging from -17 0 to +7 0 . Observations with Mariner 10 during a period of moderate solar activity in 1974 cover from 6 to 24 R/sub sun/ and from approx.20 0 to near 90 0 . We have found that the temporal frequency variance spectrum of amplitude fluctuations is useful for characterizing the bulk motion of the plasma. This spectrum has an approximately constant low frequency plateau and a power-law high frequency asymptote; the plateau-asymptote intersection frequency provides a measure of the solar wind velocity V. We also obtain the spectral index p of electron density turbulence, Phi/sub N/approx.kappa/sup -p/, where kappa is spatial wavenumber. These results apply to a cylindrical region oriented with its axis along the radio ray path and its center at the point of closest approach to the Sun. The measurements of V and p cover some 78/sup d/ for Viking and 49 2 for Mariner 10 and show the combined effects of changing heliocentric distance rho, solar latitude theta, and solar longitude Psi, as well as solar activity. The Viking results can be regarded as a function primary of rho and Psi since the observations are concentrated in the equatorial regions when solar activity was near minimum. For Mariner 10, rho, theta, and Psi variations were important. The Viking results show an abrupt change in V(rho) and the turbulence spectral index at approx.15 R/sub sun/

  11. Wave disturbances in the solar corona: radio observations at 24.5-25.5 MHz

    International Nuclear Information System (INIS)

    Kobrin, M.M.; Snegriev, S.D.

    1984-01-01

    We present an analysis of observations of fluctuations in the integrated flux of radio emission from the ''quiet'' sun. The observations were made on the UTR-2 radiotelescope, simultaneously at 11 frequencies in the range 24.5-25.5 MHz. Control observations of Taurus were made in order to allow for the effects of the earth's ionosphere. We measured the phase dependences between oscillations in the radio emission intensity which looked like wave trains. From these measurements we found that for periods of about 10 min we always observed disturbances propagating from the lower levels of the corona to the upper levels. The frequency drift in the trains is observed to be about 10 -3 MHz/sec, corresponding to a disturbance velocity of about 100 km/sec. This may be associated with the propagation of magnetosonic waves. Our estimates show that the observed effects cannot be explained by a bremsstrahlung mechanism: We need to rely on plasma mechanisms in order to explain how the radio emission is generated

  12. Effect of Short-Crestedness and Obliquity on Non-Breaking and Breaking Wave Forces Applied to Vertical Caisson Breakwaters

    DEFF Research Database (Denmark)

    Martinelli, Luca; Lamberti, Alberto; Frigaard, Peter

    2007-01-01

    This paper addresses wave forces applied to vertical caisson breakwaters. Design diagrams are proposed to evaluate the reduction of the breaker wave force with increasing horizontal length of the units. A model in 1:100 scale of a typical Italian vertical breakwater was tested under multidirectio......This paper addresses wave forces applied to vertical caisson breakwaters. Design diagrams are proposed to evaluate the reduction of the breaker wave force with increasing horizontal length of the units. A model in 1:100 scale of a typical Italian vertical breakwater was tested under...

  13. OSO 8 observations of wave propagation in the solar chromosphere and transition region

    Science.gov (United States)

    Chipman, E. G.

    1978-01-01

    The University of Colorado instrument on OSO 8 has been used to observe relative phases of the 300-s intensity variation between the temperature-minimum region and several emission lines formed in the solar chromosphere and chromosphere-corona transition region. The lines used are due to Fe II, Si II, C II, Si IV, and C IV. The scattered light in the spectrograph, which originates almost entirely in the spectral region between 1700 and 1900 A, was used as a probe of the temperature-minimum region. The lines of Fe II, Si II, and C II show almost identical delays of approximately 30 s relative to the temperature minimum, while the intensity oscillations of the lines of Si IV and C IV appear to lead the temperature-minimum intensity oscillations by about 10 s.

  14. Observations of polar patches generated by solar wind Alfvén wave coupling to the dayside magnetosphere

    Directory of Open Access Journals (Sweden)

    P. Prikryl

    wind, IMP 8 observed large amplitude Alfvén waves that were correlated with Pc5 pulsations observed by the ground magnetometers, riometers and radars. It is concluded that the FLRs and FCEs that produced patches were driven by solar wind Alfvén waves coupling to the dayside magnetosphere. During a period of southward IMF the dawn-dusk electric field associated with the Alfvén waves modulated the subsolar magnetic reconnection into pulses that resulted in convection flow bursts mapping to the ionospheric footprint of the cusp.

    Key words. Ionosphere (polar ionosphere. Magneto- spheric physics (magnetosphere-ionosphere interactions; polar wind-magnetosphere interactions.

  15. Energy loss of solar p modes due to the excitation of magnetic sausage tube waves: Importance of coupling the upper atmosphere

    International Nuclear Information System (INIS)

    Gascoyne, A.; Jain, R.; Hindman, B. W.

    2014-01-01

    We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = –z 0 ).

  16. Energy loss of solar p modes due to the excitation of magnetic sausage tube waves: Importance of coupling the upper atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Gascoyne, A.; Jain, R. [Applied Mathematics Department, University of Sheffield, Sheffield S3 7RH (United Kingdom); Hindman, B. W., E-mail: a.d.gascoyne@sheffield.ac.uk, E-mail: r.jain@sheffield.ac.uk [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, CO 80309-0440 (United States)

    2014-07-10

    We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = –z{sub 0}).

  17. Numerical study of alfvénic wave activity in the solar wind as a cause for pitch angle scattering with focus on kinetic processes

    Science.gov (United States)

    Keilbach, D.; Berger, L.; Drews, C.; Marsch, E.; Wimmer-Schweingruber, R. F.

    2017-12-01

    Recent studies, that determined the inflow longitude of the local interstellar medium from the anisotropy of interstellar pickup ion (PUI) radial velocity, have once again raised the question, how transport effects and especially wave activity in the solar wind modifies the velocity distribution function of PUIs.This study investigates the modification of an oxygen PUI torus distribution by alfvénic waves qualitatively with a numerical approach. The focus of this study is to understand this modification kinetically, which means, that instead of describing the PUI transport through diffusion approaches, we trace the trajectories of test particles in pitch angle space with a time resolution of at least 100 time steps per gyro orbit in order to find first principles of wave particle interactions on the most basic scale.Therefore we have implemented a Leapfrog solver of the Lorentz-Newton equations of motion for a charged test particle in a electro-magnetic field. The alfvénic waves were represented through a continuous circularly polarized wave superimposed to a constant 5 nT background magnetic field. In addition an electric field arising from induction has been added to the simulation's boundary conditions. The simulation code computes the particles' trajectories in the solar wind bulk system.Upon interaction with mono frequent single-frequency waves, the particles are found to perform stationary trajectories in pitch angle space, so that the pitch angle distribution of a conglomerate of test particles does not experience a systematic broadening over time. Also the particles do not react most strongly with waves at resonant frequencies, since the pitch angle modification by the waves sweeps their parallel velocity out of resonance quickly. However, within frequencies close to first order resonance, strong interactions between waves and particles are observed.Altogether the framework of our simulation is readily expandable to simulate additional effects, which may

  18. Harmonic wave model of a permanent magnet synchronous machine for modeling partial demagnetization under short circuit conditions

    NARCIS (Netherlands)

    Kral, C.; Haumer, A.; Bogomolov, M.D.; Lomonova, E.

    2012-01-01

    This paper proposes a multi domain physical model of permanent magnet synchronous machines, considering electrical, magnetic, thermal and mechanical effects. For each component of the model, the main wave as well as lower and higher harmonic wave components of the magnetic flux and the magnetic

  19. Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013

    NARCIS (Netherlands)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Phythian-Adams, A.T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.T.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, R.D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, M.J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, A.L.S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, J.G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, T.C; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, A.D.; Brown, D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderon Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglia, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Baiardi, L. Cerboni; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, D. S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Qian; Chua, S. E.; Chung, E.S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P. -F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, A.C.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J. -P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, A.L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Debra, D.; Debreczeni, G.; Degallaix, J.; De laurentis, M.; Deleglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.A.; Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Diaz, M. C.; Di Fiore, L.; Giovanni, M.G.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H. -B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, T. M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.M.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M; Fournier, J. -D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.P.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzalez, Idelmis G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Lee-Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.M.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Buffoni-Hall, R.; Hall, E. D.; Hammond, G.L.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, P.J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C. -J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J. -M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, D.H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jimenez-Forteza, F.; Johnson, W.; Jones, I.D.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.H.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kefelian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.E.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan., S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krolak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C.H.; Lee, K.H.; Lee, M.H.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lueck, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marka, S.; Marka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R.M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B.C.; Moore, J.C.; Moraru, D.; Gutierrez Moreno, M.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, S.D.; Mukherjee, S.; Mukund, K. N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P.G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Gutierrez-Neri, M.; Neunzert, A.; Newton-Howes, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J.; Oh, S. H.; Ohme, F.; Oliver, M. B.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.S; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Pereira, R.R.; Perreca, A.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Purrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosinska, D.; Rowan, S.; Ruediger, A.; Ruggi, P.; Ryan, K.A.; Sachdev, P.S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J; Schmidt, P.; Schnabel, R.B.; Schofield, R. M. S.; Schoenbeck, A.; Schreiber, K.E.C.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, M.S.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.M.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, António Dias da; Simakov, D.; Singer, A; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, R. J. E.; Smith, N.D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stiles, C.D.; Stone, J.R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S. E.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepanczyk, M. J.; Tacca, M.D.; Talukder, D.; Tanner, D. B.; Tapai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, W.R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Toyra, D.; Travasso, F.; Traylor, G.; Trifiro, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; Van Beuzekom, Martin; van den Brand, J. F. J.; Van Den Broeck, C.F.F.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasuth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P.J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Vicere, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J. -Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, MT; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L. -W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.M.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, D.R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J.L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; Zadrozny, A.; Zangrando, L.; Zanolin, M.; Zendri, J. -P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Archibald, A. M.; Banaszak, S.; Berndsen, A.; Boyles, J.; Cardoso, R. F.; Chawla, P.; Cherry, A.; Dartez, L. P.; Day-Lewis, F.D.; Epstein, C. R.; Ford, A. J.; Flanigan, J.; Garcia, A.; Hessels, J. W. T.; Hinojosa, J; Jenet, F. A.; Karako-Argaman, C.; Kaspi, V. M.; Keane, E. F.; Kondratiev, V. I.; Kramer, M.; Leake, S.; Lorimer, D.; Lunsford, G.; Lynch, R. S.; Martinez, J. G.; Mata, A.; McLaughlin, M. A.; McPhee, C. A.; Penucci, T.; Ransom, S.; Roberts, M. S. E.; Rohr, M. D. W.; Stairs, I. H.; Stovall, K.; van Leeuwen, J.; Walker, A. N.; Wells, B. L.

    2016-01-01

    We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast

  20. Solar storms; Tormentas solares

    Energy Technology Data Exchange (ETDEWEB)

    Collaboration: Pereira Cuesta, S.; Pereira Pagan, B.

    2016-08-01

    Solar storms begin with an explosion, or solar flare, on the surface of the sun. The X-rays and extreme ultraviolet radiation from the flare reach the Earths orbit minutes later-travelling at light speed. The ionization of upper layers of our atmosphere could cause radio blackouts and satellite navigation errors (GPS). Soon after, a wave of energetic particles, electrons and protons accelerated by the explosion crosses the orbit of the Earth, and can cause real and significant damage. (Author)

  1. Solar Flash Sub-Millimeter Wave Range Spectrum Part Radiation Modeling

    Directory of Open Access Journals (Sweden)

    V. Yu. Shustikov

    2015-01-01

    Full Text Available Currently, solar flares are under observation on the RT-7.5 radio telescope of BMSTU. This telescope operates in a little-studied range of the spectrum, at wavelengths of 3.2 and 2.2 mm (93 and 140 GHz, thereby providing unique information about parameters of the chromosphere plasma and zone of the temperature minimum. Observations on various instruments provided relatively small amount of data on the radio emission flare at frequencies close to 93 GHz, and at frequency of 140 GHz such observations were not carried out. For these reasons, data collected from the RT-7.5 radio telescope are of high value (Shustikov et al., 2012.This work describes modeling and gives interpretation of the reason for raising flux density spectrum of sub-millimeter radio frequency emission using as an example the GOES flare of class M 5.3 occurred on 04.07.2012 in the active region 11515. This flare was observed on the RT-7.5 radio telescope of BMSTU and was described by Shustikov et al. (2012 and by Smirnova et al. (2013, where it has been suggested that the reason for raising radio frequency emission is a bremsstrahlung of the thermal electrons in the hot plasma of the solar chromosphere. Rough estimates of the plasma temperature at the flare source were obtained.This paper proposes model calculations of the flux density spectrum of the sub-millimeter radio emission based on the gyrosynchrotron Fleischman-Kuznetsov code (Fleishman & Kuznetsov, 2010. Section 1 briefly describes observational data, tools and processing methods used in the work. Section 2 shows results of modeling the flare radio emission. Section 3 discusses results and conclusions.Numerical modeling the sub-millimeter part of the spectrum of the radio flux density for the GOES flare of class M5.3 has been carried out. This flare occurred in the active region 11515 on 04.07.2012. Modeling was based on the observations on the BMSTU’s RT-7.5 radio telescope.The paper draws conclusion based on the

  2. Feasibility Study of Using Short Wave Infrared Cavity Ringdown Spectroscopy (SWIR-CRDS) for Biological Agent Detection

    Energy Technology Data Exchange (ETDEWEB)

    Aker, Pam M.; Johnson, Timothy J.; Williams, Richard M.; Valentine, Nancy B.

    2007-10-01

    This project focused on determining the feasibility of using short wave infrared (SWIR) cavity ring down spectroscopy (CRDS) as a means for real-time detection of biological aerosols. The first part of the project involved identifying biological agent signatures that could be detected with SWIR CRDS. After an exhaustive search of the open literature it was determined that whole biological spores and/or cells would not be good candidates for direct SWIR CRDS probing because they have no unique SWIR signatures. It was postulated that while whole cells or spores are not good candidates for SWIR CRDS detection, their pyrolysis break-down products might be. A literature search was then conducted to find biological pyrolysis products with low molecular weights and high symmetry since these species most likely would have overtone and combination vibrational bands that can be detected in the SWIR. It was determined that pyrrole, pyridine and picolinamide were good candidates for evaluation. These molecules are formed when proteins and porphyrins, proteins and dipicolinic acid, and dipicolinic acid are pyrolyzed, respectively. The second part of the project involved measuring quantitative SWIR spectra of pyrrole, pyridine and picolinamide in PNNL’s FTIR Spectroscopy Laboratory. Spectral information about these molecules, in the vapor phase is sparse – there were only a few prior studies that measured line positions and no information on absorption cross sections. Absorption cross sections are needed in order to estimate the SWIR CRDS detection sensitivity, and line position determines what type of laser will be needed for the sensor. The results of the spectroscopy studies allowed us to estimate the SWIR CRDS detection sensitivity for pyrrole to be 3 x 1012 molec cm-3 or 0.1 ppmv, and for pyridine it was 1.5 x 1015 molec cm-3 or 0.6 ppmv. These detection sensitivity limits are close what we have measured for ammonia. Given these detection limits we then estimated the

  3. Sources and Propagation of High Frequency Waves in the Solar Photosphere and Chromosphere

    Science.gov (United States)

    Lawrence, John K.; Cadavid, A. C.

    2009-05-01

    We study the spatial distribution of oscillatory power in two sequences of high-cadence, high-resolution images taken by the Solar Optical Telescope on board Hinode. The sequences consist of simultaneous, co-registered G-Band (GB) and Ca II H-Line (HL) images with pixel scale 80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The first sequence has cadence 21 s over 3 hours on 2007 April 14; the other has cadence 24 s over 2 hours on 2007 March 30. Both sequences include network and internetwork at heliocentric angle 35 degrees. Time averaging of Morlet wavelet transforms gives smoothed Fourier spectra for each spatial location in the GB and HL data. We averaged over four different frequency bands to highlight different physical regimes: "evolutionary” timescales (f web of a cellular pattern with scales 2 - 3 Mm. These are found to coincide with the boundaries of stable clusters of granules. These dark boundaries may correspond to downflows that control the cell structuring and that could be the source of acoustic power.

  4. Human projected area factors for detailed direct and diffuse solar radiation analysis

    DEFF Research Database (Denmark)

    Kubaha, K.; Fiala, D.; Toftum, Jørn

    2004-01-01

    Projected area factors for individual segments of the standing and sedentary human body were modelled for both direct and diffuse solar radiation using detailed 3D geometry and radiation models. The local projected area factors with respect to direct short-wave radiation are a function of the solar...

  5. The factors influencing nonlinear characteristics of the short-circuit current in dye-sensitized solar cells investigated by a numerical model.

    Science.gov (United States)

    Shi, Yushuai; Dong, Xiandui

    2013-06-24

    A numerical model for interpretation of the light-intensity-dependent nonlinear characteristics of the short-circuit current in dye-sensitized solar cells is suggested. The model is based on the continuity equation and includes the influences of the nongeminate recombination between electrons and electron acceptors in the electrolyte and the geminate recombination between electrons and oxidized dye molecules. The influences of the order and rate constant of the nongeminate recombination reaction, the light-absorption coefficient of the dye, the film thickness, the rate constant of geminate recombination, and the regeneration rate constant on the nonlinear characteristics of the short-circuit current are simulated and analyzed. It is proposed that superlinear and sublinear characteristics of the short-circuit current should be attributed to low electron-collection efficiency and low dye-regeneration efficiency, respectively. These results allow a deep understanding of the origin of the nonlinear characteristics of the short-circuit current in solar cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. A review of vertical coupling in the Atmosphere-Ionosphere system: Effects of waves, sudden stratospheric warmings, space weather, and of solar activity

    Czech Academy of Sciences Publication Activity Database

    Yigit, E.; Koucká Knížová, Petra; Georgieva, K.; Ward, W.

    2016-01-01

    Roč. 141, April (2016), s. 1-12 ISSN 1364-6826 R&D Projects: GA ČR(CZ) GA15-24688S; GA MŠk(CZ) LG13042 Institutional support: RVO:68378289 Keywords : atmosphere–ionosphere * vertical coupling * gravity waves * tides * space weather * solar activity Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.326, year: 2016 http://www.sciencedirect.com/science/article/pii/S1364682616300426

  7. 182Hf-182W age dating of a 26Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.

    Science.gov (United States)

    Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin

    2013-05-28

    Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (26)Al, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (26)Al corresponding to (26)Al/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (26)Al/(27)Al of Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (26)Al/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (26)Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (26)Al. Admixing of stellar-derived (26)Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (26)Al-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock.

  8. Summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow. During October 1973 through September 1975

    Energy Technology Data Exchange (ETDEWEB)

    1976-12-01

    The diagrams in this section of the publication illustrate the summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow observed in Japan. For convenience, the observational results are arranged by the solar rotation number. The aim of this illustration is to disseminate an outline of daily events observed in Japan for the benefit of active research workers who plan to make detailed study of the specific solar and terrestrial events. Therefore, the illustrations do not show all observational results in Japan but only representative ones at some key stations in Japan. They will suffice for the present purpose. The method of illustration shown in the instruction on the next page is still a preliminary one, and it is subject to change resulting from the kind advice of the users of this part of the publication.

  9. Resonant excitation of coupled Rayleigh waves in a short and narrow fluid channel clad between two identical metal plates

    Directory of Open Access Journals (Sweden)

    Victor M. García-Chocano

    2011-12-01

    Full Text Available Transmission of ultrasonic waves through a slit between two water immersed brass plates is studied for sub-wavelength plate thicknesses and slit apertures. Extraordinary high absorption is observed at discrete frequencies corresponding to resonant excitation of Rayleigh waves on the both sides of the channel. The coupling of the Rayleigh waves occurs through the fluid and the corresponding contribution to the dispersion has been theoretically derived and also experimentally confirmed. Symmetric and anti-symmetric modes are predicted but only the symmetric mode resonances have been observed. It follows from the dispersion equation that the coupled Rayleigh waves cannot be excited in a channel with apertures less than the critical one. The calculated critical aperture is in a good agreement with the measured acoustic spectra. These findings could be applied to design a broadband absorptive metamaterial.

  10. Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling.

    Science.gov (United States)

    Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

    2016-09-23

    InP nanowire arrays with axial p-i-n junctions are promising devices for next-generation photovoltaics, with a demonstrated efficiency of 13.8%. However, the short-circuit current in such arrays does not match their absorption performance. Here, through combined optical and electrical modeling, we study how the absorption of photons and separation of the resulting photogenerated electron-hole pairs define and limit the short-circuit current in the nanowires. We identify how photogenerated minority carriers in the top n segment (i.e. holes) diffuse to the ohmic top contact where they recombine without contributing to the short-circuit current. In our modeling, such contact recombination can lead to a 60% drop in the short-circuit current. To hinder such hole diffusion, we include a gradient doping profile in the n segment to create a front surface barrier. This approach leads to a modest 5% increase in the short-circuit current, limited by Auger recombination with increased doping. A more efficient approach is to switch the n segment to a material with a higher band gap, like GaP. Then, a much smaller number of holes is photogenerated in the n segment, strongly limiting the amount that can diffuse and disappear into the top contact. For a 500 nm long top segment, the GaP approach leads to a 50% higher short-circuit current than with an InP top segment. Such a long top segment could facilitate the fabrication and contacting of nanowire array solar cells. Such design schemes for managing minority carriers could open the door to higher performance in single- and multi-junction nanowire-based solar cells.

  11. P Wave Duration And Dispersion In Patients With Hyperthyroidism And The Short-term Effects Of Antithyroid Treatment

    OpenAIRE

    Unal Guntekin; Yilmaz Gunes; Hakki Simsek; Mustafa Tuncer; Sevket Arslan

    2009-01-01

    Background: Prolonged P wave duration and P wave dispersion (PWD) have been associated with an increased risk for atrial fibrillation (AF). Hyperthytodism is a frequent cause of atrial fibrillation (AF). Methods: Forty-two patients with newly diagnosed overt hyperthyroidism and 20 healthy people were enrolled in the study. Transthoracic echocardiography, 12 lead surface ECG and thyroid hormone levels were studied at the time of enrollment and after achievement of euthyroid state with propylth...

  12. Cu2ZnSnS4 solar cells fabricated by short-term sulfurization of sputtered Sn/Zn/Cu precursors under an H2S atmosphere

    International Nuclear Information System (INIS)

    Emrani, Amin; Rajbhandari, Pravakar P.; Dhakal, Tara P.; Westgate, Charles R.

    2015-01-01

    Synthesis of Cu 2 ZnSnS 4 (CZTS) thin films by short-term sulfurization of sputtered Sn/Zn/Cu precursors under ambient H 2 S is studied. The effect of the sulfurization processes on the film morphology, surface roughness, composition of the CZTS, and the crystallinity was investigated by using scanning electron microscopy, optical profiler, energy dispersive spectroscopy, and X-ray diffraction respectively. To further explore the CZTS layer, the following additional layers were deposited to complete the solar cells: CdS with chemical bath deposition; ZnO and Al 2 O 3 -doped ZnO with RF magnetron deposition; and, silver fingers as the front contact as the last layer. The optical and morphological properties of the CZTS films were investigated and compared. Subsequently, the electrical characteristics and the efficiencies of the regarding solar cells were analyzed. A maximum efficiency of 3.8% has been obtained for the fast sulfurization (30 min at 580 °C) and finally, the performance is compared with our best cell fabricated through the more common slow annealing. - Highlights: • Development of Cu 2 ZnSnS 4 (CZTS) solar cells using elemental metal sputtering • 112-oriented CZTS films with well-defined mor