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Sample records for quiet solar intranetwork

  1. Does the Variation of Solar Intra-network Horizontal Field Follow Sunspot Cycle?

    NASA Astrophysics Data System (ADS)

    Jin, C. L.; Wang, J. X.

    2015-07-01

    The ubiquitousness of the solar inter-network horizontal magnetic field has been revealed by space-borne observations with high spatial resolution and polarization sensitivity. However, no consensus has been achieved on the origin of the horizontal field among solar physicists. For a better understanding, in this study, we analyze the cyclic variation of the inter-network horizontal field by using the spectro-polarimeter observations provided by the Solar Optical Telescope on board Hinode, covering the interval from 2008 April to 2015 February. The method of wavelength integration is adopted to achieve a high signal-to-noise ratio. It is found that from 2008 to 2015 the inter-network horizontal field does not vary when solar activity increases, and the average flux density of the inter-network horizontal field is 87 ± 1 G, In addition, the imbalance between horizontal and vertical fields also keeps invariant within the scope of deviation, i.e., 8.7 ± 0.5, from the solar minimum to maximum of solar cycle 24. This result confirms that the inter-network horizontal field is independent of the sunspot cycle. The revelation favors the idea that a local dynamo is creating and maintaining the solar inter-network horizontal field.

  2. The identification and interaction of network, intranetwork, and ephemeral-region magnetic fields

    NASA Technical Reports Server (NTRS)

    Martin, Sara F.

    1988-01-01

    Network magnetic fields are described as the dynamic product of the merging and cancelling of intranetwork fields, ephemeral regions, and the remnants of active regions. The similarities of these phenomena with solar magnetic features are pointed out. The intranetwork magnetic fields are characterized by the flow of successive fragments in approximately radial patterns away from their apparent source sites.

  3. Reconnection brightenings in the quiet solar photosphere

    NASA Astrophysics Data System (ADS)

    Rouppe van der Voort, Luc H. M.; Rutten, Robert J.; Vissers, Gregal J. M.

    2016-08-01

    We describe a new quiet-Sun phenomenon which we call quiet-Sun Ellerman-like brightenings (QSEB). QSEBs are similar to Ellerman bombs (EB) in some respects but differ significantly in others. EBs are transient brightenings of the wings of the Balmer Hα line that mark strong-field photospheric reconnection in complex active regions. QSEBs are similar but smaller and less intense Balmer-wing brightenings that occur in quiet areas away from active regions. In the Hα wing, we measure typical lengths of less than 0.5 arcsec, widths of 0.23 arcsec, and lifetimes of less than a minute. We discovered them using high-quality Hα imaging spectrometry from the Swedish 1-m Solar Telescope (SST) and show that, in lesser-quality data, they cannot be distinguished from more ubiquitous facular brightenings, nor in the UV diagnostics currently available from space platforms. We add evidence from concurrent SST spectropolarimetry that QSEBs also mark photospheric reconnection events, but in quiet regions on the solar surface. The movies are available in electronic form at http://www.aanda.org

  4. A theory of heating of quiet solar corona

    SciTech Connect

    Wu, C. S.; Yoon, P. H.; Wang, C. B.

    2015-03-15

    A theory is proposed to discuss the creation of hot solar corona. We pay special attention to the transition region and the low corona, and consider that the sun is quiet. The proposed scenario suggests that the protons are heated by intrinsic Alfvénic turbulence, while the ambient electrons are heated by the hot protons via collisions. The theory contains two prime components: the generation of the Alfvénic fluctuations by the heavy minor ions in the transition region and second, the explanation of the temperature profile in the low solar atmosphere. The proposed heating process operates continuously in time and globally in space.

  5. A theory of heating of quiet solar corona

    NASA Astrophysics Data System (ADS)

    Wu, C. S.; Yoon, P. H.; Wang, C. B.

    2015-03-01

    A theory is proposed to discuss the creation of hot solar corona. We pay special attention to the transition region and the low corona, and consider that the sun is quiet. The proposed scenario suggests that the protons are heated by intrinsic Alfvénic turbulence, while the ambient electrons are heated by the hot protons via collisions. The theory contains two prime components: the generation of the Alfvénic fluctuations by the heavy minor ions in the transition region and second, the explanation of the temperature profile in the low solar atmosphere. The proposed heating process operates continuously in time and globally in space.

  6. The aluminum I autoionization doublet in the quiet solar spectrum

    NASA Technical Reports Server (NTRS)

    Heasley, J. N.; Roussel-Dupre, D.; Mcallister, H. C.; Beerman, C.

    1981-01-01

    Observations are presented of the Al I autoionization doublet 1932 A and 1936 A in the quiet solar spectrum, obtained from the NRL slit spectrograph aboard Skylab and from the University of Hawaii Echelle Rocket Spectrograph. The observed profiles are compared with theoretical spectra computed for the Harvard Smithsonian Reference Atmosphere and the Vernazza, Avrett and Loeser (1976) solar models. It is found that nonlocal thermodynamic equilibrium effects are important in the line-formation problem and the synthetic spectra are in good agreeement with the data.

  7. Energy distribution of nanoflares in the quiet solar corona

    NASA Astrophysics Data System (ADS)

    Ulyanov, Artyom

    2012-07-01

    We present a detailed statistical analysis of flare-like events in low layer of solar corona detected with TESIS instrument onboard CORONAS-PHOTON satellite in 171 {Å} during high-cadence (5 sec) time-series. The estimated thermal energies of these small events amount to 10^{23} - 10^{26} erg. According to modern classification flare-like events with such energies are usually referred to as nanoflares. The big number of registered events (above 2000) allowed us to obtain precise distributions of geometric and physical parameters of nanoflares, the most intriguing being energy distribution. Following Aschwanden et al. (2000) and other authors we approximated the calculated energy distribution with a single power law slope: N(E)dE ˜ N^{-α}dE. The power law index was derived to be α = 2.4 ± 0.2, which is very close to the value reported by Krucker & Benz (1998): α ≈ 2.3 - 2.4. The total energy input from registered events constitute about 10^4 erg \\cdot cm^{-2} \\cdot s^{-1}, which is well beyond net losses in quiet corona (3 \\cdot 10^5 erg \\cdot cm^{-2} \\cdot s^{-1}). However, the value of α > 2 indicates that nanoflares with lower energies dominate over nanoflares with bigger energies and could contribute considerably to quiet corona heating.

  8. EUV brightness variations in the quiet Sun

    NASA Astrophysics Data System (ADS)

    Brković, A.; Rüedi, I.; Solanki, S. K.; Fludra, A.; Harrison, R. A.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K.

    2000-01-01

    The Coronal Diagnostic Spectrometer (CDS) onboard the SOHO satellite has been used to obtain movies of quiet Sun regions at disc centre. These movies were used to study brightness variations of solar features at three different temperatures sampled simultaneously in the chromospheric He I 584.3 Ä (2 * 104 K), the transition region O V 629.7 Ä (2.5 * 105 K) and coronal Mg IX 368.1 Ä (106 K) lines. In all parts of the quiet Sun, from darkest intranetwork to brightest network, we find significant variability in the He I and O V line, while the variability in the Mg IX line is more marginal. The relative variability, defined by rms of intensity normalised to the local intensity, is independent of brightness and strongest in the transition region line. Thus the relative variability is the same in the network and the intranetwork. More than half of the points on the solar surface show a relative variability, determined over a period of 4 hours, greater than 15.5% for the O V line, but only 5% of the points exhibit a variability above 25%. Most of the variability appears to take place on time-scales between 5 and 80 minutes for the He I and O V lines. Clear signs of ``high variability'' events are found. For these events the variability as a function of time seen in the different lines shows a good correlation. The correlation is higher for more variable events. These events coincide with the (time averaged) brightest points on the solar surface, i.e. they occur in the network. The spatial positions of the most variable points are identical in all the lines.

  9. Spatiotemporal organization of energy release events in the quiet solar corona

    SciTech Connect

    Uritsky, Vadim M.; Davila, Joseph M.

    2014-11-01

    Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfvénic interactions.

  10. Spatiotemporal Organization of Energy Release Events in the Quiet Solar Corona

    NASA Technical Reports Server (NTRS)

    Uritsky, Vadim M.; Davila, Joseph M.

    2014-01-01

    Using data from the STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfvenic interactions.

  11. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Astrophysics Data System (ADS)

    Kalkofen, Wolfgang

    2002-04-01

    The grant supported research on the structure of the quiet, nonmagnetic chromosphere and on wave excitation and propagation in both the nonmagnetic chromosphere and the magnetic network. The work on the structure of the chromosphere culminated in the recognition that between two competing views of the solar chromosphere, older models by Avrett and collaborators (referred to as VAL) and the newer, dynamical model by Carlsson & Stein (referred to as CS), the clear decision is in favor of the older models, and this in spite of the evident lack of physics, which does not include wave motion and oscillations. The contrast between the static VAL models and the dynamical CS model can be stated most succinctly by comparing the temperature variation implied by the VAL models and the temperature fluctuations of the CS model, which are, respectively, of the order of 10% for the VAL model (at heights where hydrogen is 50% ionized) and a factor of 10 (at the upper boundary of their chromospheric model). The huge fluctuations of the CS model have never been observed, whereas the smaller temperature variations of the VAL models are consistent with ground-based and space-based observations. While it should be obvious which model describes the Sun and which one fails, the case is far from settled in the minds of solar physicists. Thus, much educational work remains to be done and, of course, more research to develop arguments that make the case more convincing. The research on waves and oscillations has been based on a unified theory of excitation of acoustic waves in the field-free atmosphere and of transverse and longitudinal waves in magnetic flux tubes located in the magnetic network by noting, first, that impulsive excitation of all these waves in gravitationally stratified media leads to oscillations at the respective cutoff frequencies and, second, that the observed oscillation frequencies in the nonmagnetic and magnetic parts of the chromosphere match corresponding cutoff

  12. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang; Wagner, William J. (Technical Monitor)

    2002-01-01

    The grant supported research on the structure of the quiet, nonmagnetic chromosphere and on wave excitation and propagation in both the nonmagnetic chromosphere and the magnetic network. The work on the structure of the chromosphere culminated in the recognition that between two competing views of the solar chromosphere, older models by Avrett and collaborators (referred to as VAL) and the newer, dynamical model by Carlsson & Stein (referred to as CS), the clear decision is in favor of the older models, and this in spite of the evident lack of physics, which does not include wave motion and oscillations. The contrast between the static VAL models and the dynamical CS model can be stated most succinctly by comparing the temperature variation implied by the VAL models and the temperature fluctuations of the CS model, which are, respectively, of the order of 10% for the VAL model (at heights where hydrogen is 50% ionized) and a factor of 10 (at the upper boundary of their chromospheric model). The huge fluctuations of the CS model have never been observed, whereas the smaller temperature variations of the VAL models are consistent with ground-based and space-based observations. While it should be obvious which model describes the Sun and which one fails, the case is far from settled in the minds of solar physicists. Thus, much educational work remains to be done and, of course, more research to develop arguments that make the case more convincing. The research on waves and oscillations has been based on a unified theory of excitation of acoustic waves in the field-free atmosphere and of transverse and longitudinal waves in magnetic flux tubes located in the magnetic network by noting, first, that impulsive excitation of all these waves in gravitationally stratified media leads to oscillations at the respective cutoff frequencies and, second, that the observed oscillation frequencies in the nonmagnetic and magnetic parts of the chromosphere match corresponding cutoff

  13. Quiet-time electron increases, a measure of conditions in the outer solar system

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.; Vanhollebeke, M.

    1972-01-01

    One possible explanation for quiet-time electron increases, increases in the intensity of 3-12 MeV interplanetary electrons that have been reported by McDonald, Cline and Simnett, is discussed. It is argued that the electrons in quiet-time increases are galactic in origin, but that the observed increases are not the result of any variation in the modulation of these particles in the inner solar system. It is suggested instead that quiet-time increases may occur when more electrons than normal penetrate a modulating region that lies far beyond the orbit of earth. The number of electrons penetrating this region may increase when field lines that have experienced an unusually large random walk in the photosphere are carried by the solar wind out to the region. As evidence for this increased random walk, it is shown that five solar rotations before most of the quiet-time increases there is an extended period when the amplitude of the diurnal anisotropy, as is measured by the Deep River neutron monitor, is relatively low. Five rotations delay time implies that the proposed modulating region lies at approximately 30 AU from the Sun, assuming that the average solar wind speed is constant over this distance at approximately 400 km/sec.

  14. High-Resolution Microwave Observations of the Quiet Solar Chromosphere

    NASA Astrophysics Data System (ADS)

    Bastian, T. S.; Dulk, G. A.; Leblanc, Y.

    1996-12-01

    The VLA was used to observe a quiet region of the Sun on 1992 September 23 at 1.3 and 2 cm. Unlike previous interferometric microwave observations of the quiet Sun, we have used the total power data to calibrate the brightness temperature distribution in an absolute sense. We find a good correlation between the time-averaged 1.3 and 2 cm brightness distributions, and, in agreement with past studies at 3.6 and 6 cm, we find that both the 1.3 and 2 cm brightness distributions are closely correlated with the network magnetic field. The mean brightness at 1.3 and 2 cm was 10,400±1230 K and 12890±1415 K, respectively. The width of the σ1.3 cm brightness distribution function is σ1.3 = 270 K, while that at 2 cm is σ2 = 460 K. We have examined the time variability of the 1.3 and 2 cm emission on a timescale of 2 hr. The correlation between the 1.3 and 2 cm brightness distributions is maintained, as is the correlation with the underlying magnetic field. However, considerable variability in the details of the brightness distribution is evident during the course of the day. We compare our mean brightness measurements with those of Zirin, Baumert, & Hurford and compare the ensemble of observations with semi-empirical models of the chromosphere and transition region. The MCO model proposed by Avrett, which is in agreement with carbon monoxide observations, yields a microwave brightness temperature spectrum that is in excellent agreement with the microwave observations of Zirin et al. and those reported in this paper. The need for a model that reconciles all chromospheric observations optical, UV, infrared, and radio remains however. Inhomogeneous and/or dynamic chromospheric models are likely required.

  15. Penetration boundary of solar cosmic rays into the earth's magnetosphere during magnetically quiet times

    SciTech Connect

    Biryukov, A.S.; Ivanova, T.A.; Kovrygina, L.M.; Kudels, K.; Kuznetsov, S.N.; Sosnovets, E.N.; Tuerskaya, L.V.

    1984-05-01

    Data is used from the satellites Interkosmos-17 and Kosmos-900 to determine penetration boundaries at high latitudes in the earth's magnetosphere. Considered are the results of observations of the penetration boundary of solar cosmic ray (SCR) protons and electrons during an SCR increase on November 22-25, 1977. The position of the SCR penetration boundary during a single increase at practically all values of MLT in quiet conditions is examined. Magnetospheric structure is determined in the region of closed drift shells where the magnetic field is asymmetric. The authors can estimate how the solar wind pressure affects the magnetosphere by using data on the penetration boundaries of solar protons obtained during quiet geomagnetic conditions.

  16. QUIET-TIME INTERPLANETARY {approx}2-20 keV SUPERHALO ELECTRONS AT SOLAR MINIMUM

    SciTech Connect

    Wang, Linghua; Lin, Robert P.; Salem, Chadi; Pulupa, Marc; Larson, Davin E.; Luhmann, Janet G.; Yoon, Peter H.

    2012-07-01

    We present a statistical survey of {approx}2-20 keV superhalo electrons in the solar wind measured by the SupraThermal Electron instrument on board the two STEREO spacecraft during quiet-time periods from 2007 March through 2009 March at solar minimum. The observed superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f{proportional_to}v{sup -{gamma}}, with {gamma} ranging from 5 to 8.7, with nearly half between 6.5 and 7.5, and an average index of 6.69 {+-} 0.90. The observed power-law spectrum varies significantly on a spatial scale of {approx}>0.1 AU and a temporal scale of {approx}>several days. The integrated density of quiet-time superhalo electrons at 2-20 keV ranges from {approx}10{sup -8} cm{sup -3} to 10{sup -6} cm{sup -3}, about 10{sup -9}-10{sup -6} of the solar wind density, and, as well as the power-law spectrum, shows no correlation with solar wind proton density, velocity, or temperature. The density of superhalo electrons appears to show a solar-cycle variation at solar minimum, while the power-law spectral index {gamma} has no solar-cycle variation. These quiet-time superhalo electrons are present even in the absence of any solar activity-e.g., active regions, flares or microflares, type III radio bursts, etc.-suggesting that they may be accelerated by processes such as resonant wave-particle interactions in the interplanetary medium, or possibly by nonthermal processes related to the acceleration of the solar wind such as nanoflares, or by acceleration at the CIR forward shocks.

  17. Dependence of Quiet Time Geomagnetic Activity Seasonal Variation on the Solar Magnetic Polarity

    NASA Astrophysics Data System (ADS)

    Oh, Suyeon

    2013-03-01

    The geomagnetic activity shows the semiannual variation stronger in vernal and autumnal equinoxes than in summer and winter solstices. The semiannual variation has been explained by three main hypotheses such as Axial hypothesis, Equinoctial hypothesis, and Russell-McPherron Effect. Many studies using the various geomagnetic indices have done to support three main hypotheses. In recent, Oh & Yi (2011) examined the solar magnetic polarity dependency of the geomagnetic storm occurrence defined by Dst index. They reported that there is no dependency of the semiannual variation on the sign of the solar polar fields. This study examines the solar magnetic polarity dependency of quiet time geomagnetic activity. Using Dxt index (Karinen & Mursula 2005) and Dcx index (Mursula & Karinen 2005) which are recently suggested, in addition to Dst index, we analyze the data of three-year at each solar minimum for eight solar cycles since 1932. As a result, the geomagnetic activity is stronger in the period that the solar magnetic polarity is anti-parallel with the Earth's magnetic polarity. There exists the difference between vernal and autumnal equinoxes regarding the solar magnetic polarity dependency. However, the difference is not statistically significant. Thus, we conclude that there is no solar magnetic polarity dependency of the semiannual variation for quiet time geomagnetic activity.

  18. Simulation of Quiet-Sun Hard X-Rays Related to Solar Wind Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Wang, Linghua; Krucker, Säm; Hannah, Iain

    2016-05-01

    In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into the interplanetary medium, to form a superhalo electron population measured in the solar wind. After considering the electron energy loss due to Coulomb collisions and the ambipolar electrostatic potential, we find that the sources of the superhalo could only occur high in the corona (at a heliocentric altitude {≳} 1.9 R_{⊙} (the mean radius of the Sun)), to remain a power-law shape of electron spectrum as observed by Solar Terrestrial Relations Observatory (STEREO) at 1 AU near solar minimum (Wang et al. in Astrophys. J. Lett. 753, L23, 2012). The modeled quiet-Sun HXRs related to the superhalo electrons fit well to a power-law spectrum, f ˜ ɛ^{-γ} in the photon energy ɛ, with an index γ≈2.0 - 2.3 (3.3 - 3.7) at 10 - 100 keV, for the warm/cold-thick-target (thin-target) emissions produced by the downward-traveling (upward-traveling) accelerated electrons. These simulated quiet-Sun spectra are significantly harder than the observed spectra of most solar HXR flares. Assuming that the quiet-Sun sources cover 5 % of the solar surface, the modeled thin-target HXRs are more than six orders of magnitude weaker than the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) upper limit for quiet-Sun HXRs (Hannah et al. in Astrophys. J. 724, 487, 2010). Using the thick-target model for the downward-traveling electrons, the RHESSI upper limit restricts the number of downward-traveling electrons to at most {≈} 3 times the number of escaping electrons. This ratio is fundamentally different from what is observed during solar flares associated with escaping electrons where the fraction of downward-traveling electrons dominates by a factor of 100 to 1000 over the escaping population.

  19. Simulation of Quiet-Sun Hard X-Rays Related to Solar Wind Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Wang, Linghua; Krucker, Säm; Hannah, Iain

    2016-05-01

    In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into the interplanetary medium, to form a superhalo electron population measured in the solar wind. After considering the electron energy loss due to Coulomb collisions and the ambipolar electrostatic potential, we find that the sources of the superhalo could only occur high in the corona (at a heliocentric altitude ≳ 1.9 R_{⊙} (the mean radius of the Sun)), to remain a power-law shape of electron spectrum as observed by Solar Terrestrial Relations Observatory (STEREO) at 1 AU near solar minimum (Wang et al. in Astrophys. J. Lett. 753, L23, 2012). The modeled quiet-Sun HXRs related to the superhalo electrons fit well to a power-law spectrum, f ˜ ɛ^{-γ} in the photon energy ɛ, with an index γ≈2.0 - 2.3 (3.3 - 3.7) at 10 - 100 keV, for the warm/cold-thick-target (thin-target) emissions produced by the downward-traveling (upward-traveling) accelerated electrons. These simulated quiet-Sun spectra are significantly harder than the observed spectra of most solar HXR flares. Assuming that the quiet-Sun sources cover 5 % of the solar surface, the modeled thin-target HXRs are more than six orders of magnitude weaker than the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) upper limit for quiet-Sun HXRs (Hannah et al. in Astrophys. J. 724, 487, 2010). Using the thick-target model for the downward-traveling electrons, the RHESSI upper limit restricts the number of downward-traveling electrons to at most {≈} 3 times the number of escaping electrons. This ratio is fundamentally different from what is observed during solar flares associated with escaping electrons where the fraction of downward-traveling electrons dominates by a factor of 100 to 1000 over the escaping population.

  20. Cloud modeling of a quiet solar region in Halpha .

    NASA Astrophysics Data System (ADS)

    Bostanci, Z. F.; Al Erdoğan, N.

    We present chromospheric cloud modeling on the basis of Halpha profile-sampling images taken with the Interferometric Bidimensional Spectrometer (IBIS) at the Dunn Solar Telescope (DST). We choose the required reference background profile by using theoretical NLTE profile synthesis. The resulting cloud parameters are converted into estimates of physical parameters (temperature and various densities). Their mean values compare well with the VAL-C model.

  1. Structure and Dynamics of the Quiet Solar Chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang; Wagner, William (Technical Monitor)

    2003-01-01

    For the meeting of the AAS/SPD in Albuquerque, NM, I organized a Topical Session of the AAS on Structure and Dynamics of Chromospheres. The grant support was used to bring to the US two of the speakers from abroad. I had invited them for presentations at the Session: Dr. Klaus Wilhelm, the former PI of the SUMER instrument on SOHO, from the Max-Planck Institut in Lindau, Germany, and Dr. Sirajul Hasan, from the Indian Institute of Astrophysics in Bangalore, India. Both speakers preceded their trip to the AAS meeting with a stay at the Smithsonian Astrophysical Observatory, where they interacted with members of the Solar and Stellar Physics division. The highlights of the visits were the talks at the AAS/SPD meeting, in which six invited speakers told the audience of astronomers about current problems in solar physics and their relation to stellar problems. An important result of the visits is a paper by Dr. Wilhelm and me on 'Observations of the upper solar chromosphere with SUMER on SOHO', which has been submitted to Astronomy and Astrophysics for publication.

  2. Relation between Intensity Contrast and Magnetic Field for Active and Quiet Regions Observed on the Solar Photosphere

    NASA Astrophysics Data System (ADS)

    Whitney, Taylor; Criscuoli, Serena; Norton, Aimee Ann

    2016-05-01

    Current solar modeling techniques assume that active and quiet regions can be considered in the same manner. However, recent results from numerical simulations and high-spatial resolution observations indicate that radiative properties of small magnetic elements depend on whether they are located in plages, network, or quiet areas. These studies have been carried out typically at, or close to, disk center. In this study, data from the Helioseismic Magnetic Imager (HMI) are used to investigate the differences between magnetic elements located in Network/Quiet and Active Regions (AR) observed at different positions over the solar disk.

  3. Contributions of Active Regions, Sunspots, Quiet Sun to the Solar UV Spectrum

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; McMullin, D. R.; Cookson, A.; Chapman, G. A.

    2013-12-01

    During the declining phase of the most recent solar cycle, the full disk solar UV spectrum was measured by several space-based instruments, including the SOLSTICE and SIM instruments on the SORCE satellite and the SUSIM instrument on the UARS satellite. These results show distinctively different behavior and have implications for our understanding of the contributions played by various surface features in producing the disk integrated UV spectrum as well as the impact of solar UV emissions on climate. The primary goal of this study is to determine the impact of regions of increased activity (e.g. plage and sunspots) during the recent solar cycle and how this relates to variability of the solar spectrum. Two important results from this study will be the plage and sunspot UV contrast compared to the quiet as well as the center to limb variability of plage, sunspots, and the quiet sun at UV wavelengths. This study will estimate the solar spectrum by utilizing the recently digitized UV spectral radiance observations of plage, sunspots, the quiet sun made by the S082B spectrograph on Skylab, Ca II K images collected at San Fernando Observatory during the recent solar cycle, and a solar spectral model developed under a previous NASA grant. Once generated, these spectra will be compared to the UV observations produced by the above instruments. An important step in the estimation process involves the calibration of the Skylab data for a valid comparison between model and observed spectra. This will require separate calibration curves for SUSIM and SORCE observations. These will be generated from days of no or minimal activity. The determination of separate calibrations will allow any subtle contributions due to variations in instrument performance to be accounted for in the comparison of model and observed spectra. Also, changes in instrumental behavior over time will be separable from real changes in the solar spectrum which are due to contributions of active solar

  4. Contributions of Active Regions, Sunspots, Quiet Sun to the Solar UV Spectrum

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; McMullin, D. R.; Cookson, A.; Chapman, G. A.

    2011-12-01

    During the declining phase of the most recent solar cycle, the full disk solar UV spectrum was measured by several space-based instruments, including the SOLSTICE and SIM instruments on the SORCE satellite and the SUSIM instrument on the UARS satellite. These results show distinctively different behavior and have implications for our understanding of the contributions played by various surface features in producing the disk integrated UV spectrum as well as the impact of solar UV emissions on climate. The primary goal of this study is to determine the impact of regions of increased activity (e.g. plage and sunspots) during the recent solar cycle and how this relates to variability of the solar spectrum. Two important results from this study will be the plage and sunspot UV contrast compared to the quiet as well as the center to limb variability of plage, sunspots, and the quiet sun at UV wavelengths. This study will estimate the solar spectrum by utilizing the recently digitized UV spectral radiance observations of plage, sunspots, the quiet sun made by the S082B spectrograph on Skylab, Ca II K images collected at San Fernando Observatory during the recent solar cycle, and a solar spectral model developed under a previous NASA grant. Once generated, these spectra will be compared to the UV observations produced by the above instruments. An important step in the estimation process involves the calibration of the Skylab data for a valid comparison between model and observed spectra. This will require separate calibration curves for SUSIM and SORCE observations. These will be generated from days of no or minimal activity. The determination of separate calibrations will allow any subtle contributions due to variations in instrument performance to be accounted for in the comparison of model and observed spectra. Also, changes in instrumental behavior over time will be separable from real changes in the solar spectrum which are due to contributions of active solar

  5. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times.

    PubMed

    Shi, Q Q; Zong, Q-G; Fu, S Y; Dunlop, M W; Pu, Z Y; Parks, G K; Wei, Y; Li, W H; Zhang, H; Nowada, M; Wang, Y B; Sun, W J; Xiao, T; Reme, H; Carr, C; Fazakerley, A N; Lucek, E

    2013-01-01

    An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times. PMID:23403567

  6. Observations of the brightness temperature distribution of the quiet solar corona at decametric wavelengths

    NASA Technical Reports Server (NTRS)

    Sastry, Ch. V.

    1987-01-01

    The brightness temperature distribution of the quiet solar corona at a wavelength of 8.9 meters is measured by two types of radio telescope: (1) a 'T' type array with a resolution of 26'X38', and (2) a fan beam interferometer with an E-W resolution of 3'. It is found that the persistent bright regions do not have any angular structure on scales of 6' or less. The daily variations of the brightness temperature of different regions are studied and the possible interpretation discussed.

  7. Solar quiet day ionospheric source current in the West African region

    PubMed Central

    Obiekezie, Theresa N.; Okeke, Francisca N.

    2012-01-01

    The Solar Quiet (Sq) day source current were calculated using the magnetic data obtained from a chain of 10 magnetotelluric stations installed in the African sector during the French participation in the International Equatorial Electrojet Year (IEEY) experiment in Africa. The components of geomagnetic field recorded at the stations from January–December in 1993 during the experiment were separated into the source and (induced) components of Sq using Spherical Harmonics Analysis (SHA) method. The range of the source current was calculated and this enabled the viewing of a full year’s change in the source current system of Sq. PMID:25685434

  8. Solar quiet day ionospheric source current in the West African region.

    PubMed

    Obiekezie, Theresa N; Okeke, Francisca N

    2013-05-01

    The Solar Quiet (Sq) day source current were calculated using the magnetic data obtained from a chain of 10 magnetotelluric stations installed in the African sector during the French participation in the International Equatorial Electrojet Year (IEEY) experiment in Africa. The components of geomagnetic field recorded at the stations from January-December in 1993 during the experiment were separated into the source and (induced) components of Sq using Spherical Harmonics Analysis (SHA) method. The range of the source current was calculated and this enabled the viewing of a full year's change in the source current system of Sq. PMID:25685434

  9. Alfvénic waves with sufficient energy to power the quiet solar corona and fast solar wind.

    PubMed

    McIntosh, Scott W; De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo; Boerner, Paul; Goossens, Marcel

    2011-07-28

    Energy is required to heat the outer solar atmosphere to millions of degrees (refs 1, 2) and to accelerate the solar wind to hundreds of kilometres per second (refs 2-6). Alfvén waves (travelling oscillations of ions and magnetic field) have been invoked as a possible mechanism to transport magneto-convective energy upwards along the Sun's magnetic field lines into the corona. Previous observations of Alfvénic waves in the corona revealed amplitudes far too small (0.5 km s(-1)) to supply the energy flux (100-200 W m(-2)) required to drive the fast solar wind or balance the radiative losses of the quiet corona. Here we report observations of the transition region (between the chromosphere and the corona) and of the corona that reveal how Alfvénic motions permeate the dynamic and finely structured outer solar atmosphere. The ubiquitous outward-propagating Alfvénic motions observed have amplitudes of the order of 20 km s(-1) and periods of the order of 100-500 s throughout the quiescent atmosphere (compatible with recent investigations), and are energetic enough to accelerate the fast solar wind and heat the quiet corona. PMID:21796206

  10. NEW SOLAR TELESCOPE OBSERVATIONS OF MAGNETIC RECONNECTION OCCURRING IN THE CHROMOSPHERE OF THE QUIET SUN

    SciTech Connect

    Chae, Jongchul; Ahn, K.; Goode, P. R.; Yurchysyn, V.; Abramenko, V.; Andic, A.; Cao, W.; Park, Y. D.

    2010-04-10

    Magnetic reconnection is a process in which field-line connectivity changes in a magnetized plasma. On the solar surface, it often occurs with the cancellation of two magnetic fragments of opposite polarity. Using the 1.6 m New Solar Telescope, we observed the morphology and dynamics of plasma visible in the H{alpha} line, which is associated with a canceling magnetic feature (CMF) in the quiet Sun. The region can be divided into four magnetic domains: two pre-reconnection and two post-reconnection. In one post-reconnection domain, a small cloud erupted, with a plane-of-sky speed of 10 km s{sup -1}, while in the other one, brightening began at points and then tiny bright loops appeared and subsequently shrank. These features support the notion that magnetic reconnection taking place in the chromosphere is responsible for CMFs.

  11. A measurement of the quiet network contribution to solar irradiance variation

    NASA Astrophysics Data System (ADS)

    Foukal, Peter; Milano, Leo

    A large increase in quiet network area since the 17th century Maunder Minimum has been suggested as a mechanism for increasing solar irradiance sufficiently to drive global warming. We show that this mechanism requires essentially complete disappearance of network proceeding back in time to the beginning of the 20th century. This disappearance is ruled out by the many Ca K spectroheliograms taken since the discovery of the network in the early 1890's. Furthermore, network area measurements we have carried out on Ca K spectroheliograms digitized from the Mt. Wilson and NSO/Sacramento Peak archives, for the nine solar activity minima between 1914 and 1996, show no evidence of network area variations large enough to produce a significant long-term component of total irradiance variation. A network brightness variation of sufficient magnitude is also unlikely, given the linear dependence of solar microwave flux on area of bright structures.More generally, recent analyses of cycle 21,22 pyrheliometry, and of broadband stellar photometry, provide little support for any long-term irradiance component These results do not rule out a secular irradiance increase. But they suggest that high climate sensitivity to the relatively small changes in solar total and UV irradiance that have been observed, provides a more likely explanation of the global temperature-solar activity correlation.

  12. SCATTERING POLARIZATION OF THE Ca II IR TRIPLET FOR PROBING THE QUIET SOLAR CHROMOSPHERE

    SciTech Connect

    Manso Sainz, R.; Trujillo Bueno, J. E-mail: jtb@iac.e

    2010-10-20

    The chromosphere of the quiet Sun is a very important stellar atmospheric region whose thermal and magnetic structure we need to decipher in order to unlock new discoveries in solar and stellar physics. To this end, we need to identify and exploit observables sensitive to weak magnetic fields (B {approx}< 100 G) and to the presence of cool and hot gas in the bulk of the solar chromosphere. Here, we report on an investigation of the Hanle effect in two semi-empirical models of the quiet solar atmosphere with different chromospheric thermal structures. Our study reveals that the linear polarization profiles produced by scattering in the Ca II IR triplet have thermal and magnetic sensitivities potentially of great diagnostic value. The linear polarization in the 8498 A line shows a strong sensitivity to inclined magnetic fields with strengths between 0.001 and 10 G, while the emergent linear polarization in the 8542 A and 8662 A lines is mainly sensitive to magnetic fields with strengths between 0.001 and 0.1 G. The reason for this is that the scattering polarization of the 8542 A and 8662 A lines, unlike the 8498 A line, is controlled mainly by the Hanle effect in their (metastable) lower levels. Therefore, in regions with magnetic strengths noticeably larger than 1 G, their Stokes Q and U profiles are sensitive only to the orientation of the magnetic field vector. We also find that for given magnetic field configurations the sign of the Q/I and U/I profiles of the 8542 A and 8662 A lines is the same in both atmospheric models, while the sign of the linear polarization profile of the 8498 A line turns out to be very sensitive to the thermal structure of the lower chromosphere. We suggest that spectropolarimetric observations providing information on the relative scattering polarization amplitudes of the Ca II IR triplet will be very useful to improve our empirical understanding of the thermal and magnetic structure of the quiet chromosphere.

  13. Quiet-Time Spectra and Abundances of Energetic Particles During the 1996 Solar Minimum

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1999-01-01

    We report the energy spectra and abundances of ions with atomic number, Z, in the interval Z is greater than or equal to 2 and Z is less than or equal to 36 and energies approximately 3-20 MeV/amu for solar and interplanetary quiet periods between 1994 November and 1998 April as measured by the large-geometry Low Energy Matrix Telescope (LEMT) telescope on the Wind spacecraft near Earth. The energy spectra show the presence of galactic (GCR) and "anomalous" cosmic ray (ACR) components, depending on the element. ACR components are reported for Mg and Si for the first time at 1 AU and the previous observation of S and Ar is confirmed. However, only GCR components are clearly apparent for the elements Ca, Ti, Cr, Fe, as well as for C. New limits are placed on a possible ACR contribution for other elements, including Kr.

  14. Quiet-Time Spectra and Abundances of Energetic Particles During the 1996 Solar Minimum

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1998-01-01

    This report concerns the energy spectra and abundances of ions with atomic number, Z, in the interval 2 greater than or equal to Z and Z less than or equal to 36 and energies approximately 3-20 MeV/amu for solar and interplanetary quiet periods between November 1994 and April 1998 as measured by the large-geometry LEMT telescope on the Wind spacecraft near Earth. The energy spectra show the presence of galactic (GCR) and 'anomalous' cosmic ray (ACR) components, depending on the element. ACR components are reported for Mg and Si for the first time at 1 AU and the previous observation of S and Ar is confirmed. However, only GCR components are clearly apparent for the elements Ca, Ti, Cr, Fe, as well as for C. New limits are placed on a possible ACR contribution for other elements, including Kr.

  15. Markov Properties of the Magnetic Field in the Quiet Solar Photosphere

    NASA Astrophysics Data System (ADS)

    Gorobets, A. Y.; Borrero, J. M.; Berdyugina, S.

    2016-07-01

    The observed magnetic field on the solar surface is characterized by a very complex spatial and temporal behavior. Although feature-tracking algorithms have allowed us to deepen our understanding of this behavior, subjectivity plays an important role in the identification and tracking of such features. In this paper, we study the temporal stochasticity of the magnetic field on the solar surface without relying on either the concept of magnetic feature or on the subjective assumptions about their identification and interaction. The analysis is applied to observations of the magnetic field of the quiet solar photosphere carried out with the Imaging Magnetograph eXperiment (IMaX) instrument on board the stratospheric balloon, Sunrise. We show that the joint probability distribution functions of the longitudinal ({B}\\parallel ) and transverse ({B}\\perp ) components of the magnetic field, as well as of the magnetic pressure ({B}2={B}\\perp 2+{B}\\parallel 2), verify the necessary and sufficient condition for the Markov chains. Therefore, we establish that the magnetic field as seen by IMaX with a resolution of 0.″15–0.″18 and 33 s cadence, which can be considered as a memoryless temporal fluctuating quantity.

  16. Aircraft Crew Radiation Exposure in Aviation Altitudes During Quiet and Solar Storm Periods

    NASA Astrophysics Data System (ADS)

    Beck, Peter

    The European Commission Directorate General Transport and Energy published in 2004 a summary report of research on aircrew dosimetry carried out by the EURADOS working group WG5 (European Radiation Dosimetry Group, http://www.eurados.org/). The aim of the EURADOS working group WG5 was to bring together, in particular from European research groups, the available, preferably published, experimental data and results of calculations, together with detailed descriptions of the methods of measurement and calculation. The purpose is to provide a dataset for all European Union Member States for the assessment of individual doses and/or to assess the validity of different approaches, and to provide an input to technical recommendations by the experts and the European Commission. Furthermore EURADOS (European Radiation Dosimetry Group, http://www.eurados.org/) started to coordinate research activities in model improvements for dose assessment of solar particle events. Preliminary results related to the European research project CONRAD (Coordinated Network for Radiation Dosimetry) on complex mixed radiation fields at workplaces are presented. The major aim of this work is the validation of models for dose assessment of solar particle events, using data from neutron ground level monitors, in-flight measurement results obtained during a solar particle event and proton satellite data. The radiation protection quantity of interest is effective dose, E (ISO), but the comparison of measurement results obtained by different methods or groups, and comparison of measurement results and the results of calculations, is done in terms of the operational quantity ambient dose equivalent, H* (10). This paper gives an overview of aircrew radiation exposure measurements during quiet and solar storm conditions and focuses on dose results using the EURADOS In-Flight Radiation Data Base and published data on solar particle events

  17. DETECTION OF SMALL-SCALE GRANULAR STRUCTURES IN THE QUIET SUN WITH THE NEW SOLAR TELESCOPE

    SciTech Connect

    Abramenko, V. I.; Yurchyshyn, V. B.; Goode, P. R.; Kitiashvili, I. N.; Kosovichev, A. G.

    2012-09-10

    Results of a statistical analysis of solar granulation are presented. A data set of 36 images of a quiet-Sun area on the solar disk center was used. The data were obtained with the 1.6 m clear aperture New Solar Telescope at Big Bear Solar Observatory and with a broadband filter centered at the TiO (705.7 nm) spectral line. The very high spatial resolution of the data (diffraction limit of 77 km and pixel scale of 0.''0375) augmented by the very high image contrast (15.5% {+-} 0.6%) allowed us to detect for the first time a distinct subpopulation of mini-granular structures. These structures are dominant on spatial scales below 600 km. Their size is distributed as a power law with an index of -1.8 (which is close to the Kolmogorov's -5/3 law) and no predominant scale. The regular granules display a Gaussian (normal) size distribution with a mean diameter of 1050 km. Mini-granular structures contribute significantly to the total granular area. They are predominantly confined to the wide dark lanes between regular granules and often form chains and clusters, but different from magnetic bright points. A multi-fractality test reveals that the structures smaller than 600 km represent a multi-fractal, whereas on larger scales the granulation pattern shows no multi-fractality and can be considered as a Gaussian random field. The origin, properties, and role of the population of mini-granular structures in the solar magnetoconvection are yet to be explored.

  18. The angular distribution of solar wind ˜20-200 keV superhalo electrons at quiet times

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Wang, Linghua; Li, Gang; He, Jiansen; Salem, Chadi S.; Tu, Chuanyi; Wimmer-Schweingruber, Robert F.; Bale, Stuart D.

    2016-03-01

    We present a comprehensive study of the angular distribution of ˜20-200 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet times from 1995 January through 2005 December. According to the interplanetary magnetic field, we re-bin the observed electron pitch angle distributions to obtain the differential flux, Jout (Jin), of electrons traveling outward from (inward toward) the Sun, and define the anisotropy of superhalo electrons as A =2/(Jo u t-Ji n) Jo u t+Ji n at a given energy. We found that for out in ˜96% of the selected quiet-time samples, superhalo electrons have isotropic angular distributions, while for ˜3% (˜1%) of quiet-time samples, superhalo electrons are outward-anisotropic (inward-anisotropic). All three groups of angular distributions show no correlation with the local solar wind plasma, interplanetary magnetic field and turbulence. Furthermore, the superhalo electron spectral index shows no correlation with the spectral index of local solar wind turbulence. These quiet-time superhalo electrons may be accelerated by nonthermal processes related to the solar wind source and strongly scattered/ reflected in the interplanetary medium, or could be formed due to the electron acceleration through the interplanetary medium.

  19. The energy spectrum of 0.16 to 2 MeV electrons during solar quiet times

    NASA Technical Reports Server (NTRS)

    Hurford, G. J.; Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1974-01-01

    New observations of the quiet-time energy spectrum of 0.16 to 2 MeV electrons were made with the Caltech Electron/Isotope Spectrometer which was launched on IMP-7 in September 1972. Earlier measurements of quiet-time electrons in this energy range by other groups have resulted in spectra differing by more than an order of magnitude in intensity. A minimum quiet-time flux somewhat lower than the lowest previously reported spectra and consistent with an extrapolation of the spectrum measured at higher energies was found. A galactic secondary source of knock-on electrons is consistent with the results and with independent studies of the interstellar spectra of cosmic ray nuclei provided that solar modulation does not suppress the 0.162 MeV electron flux by more than a factor of approximately 3. Although not required, other recently suggested sources may also contribute to the observed fluxes.

  20. Spatial variability of solar quiet fields along 96° magnetic meridian in Africa: Results from MAGDAS

    NASA Astrophysics Data System (ADS)

    Bolaji, O. S.; Rabiu, A. B.; Bello, O. R.; Yoshikawa, A.; Yumoto, K.; Odeyemi, O. O.; Ogunmodimu, O.

    2015-05-01

    We have used chains of Magnetic Data Acquisition System (MAGDAS) magnetometer records of the horizontal (H) and vertical (Z) magnetic field intensities during September 2008 to August 2009 (year of deep minimum) across Africa to study their variability during the quietest international days, which coincidently associated with the sudden stratospheric warming (SSW) event in January 2009. This selection of the most international quiet days is indicative of 80% that are strongly associated with days when unusually strong and prolonged sudden SSW event occurs in January 2009. Interestingly, in January, a significant magnitude depletion of solar quiet (Sq) equivalent current was observed near noon hours around the magnetic equator (Addis Ababa, ABB) compared to any other months along with a consistent significantly reduced value across the Northern Hemisphere and moderate decrease at the Southern Hemisphere. Also, we found that Nairobi and Dar es Salaam at the Southern Hemisphere, which are close to ABB (dip equator), are strongly prone to westward electric field compared to the magnetic equator and Khartoum at the Northern Hemisphere. Significant negative values of MSq(Z) magnitudes observed near noon hours at Hermanus indicate the presence of induced currents that suggest ocean effects along with reversal to significant positive values in the afternoon, which subsided before 1800 LT in almost all the months, indicate stronger influence of ionospheric currents. On seasonal variability of Sq(H), a slight depression at ABB during September equinox is one of the evidences of seasonal Sq focus shift. Latitudinal variability of Sq near-noon hours was also investigated.

  1. On the Solar Quiet Variation Measured in Latin America by the Embrace Magnetometer Network

    NASA Astrophysics Data System (ADS)

    Denardini, Clezio Marcos; Moro, Juliano; Araujo Resende, Laysa Cristina; Chen, Sony Su

    2016-07-01

    The present work show the first results of the study about the seasonal variation of the Solar quiet (Sq) Earth's magnetic field based on magnetic measurements from the Embrace Magnetic Network (MagNet) at several latitudes in South America, covering the equatorial and low latitudinal region. For this study, we used data covering the period from September 2010 to December 2015, during the ascending phase of the solar cycle 24. Before analyzing the magnetic data collected from the Embrace Magnet, we compared the magnetic data collected by the Embrace variometer installed at Vassouras-RJ, in Brazil, with the same data collected by the absolute magnetometer installed by the Intermagnet at the same observatory. We show that our data is in pretty good agreement to the absolute values. With respect to the seasonal variation, we show clear seasonal modulation in all components, irrespective the latitude. The H component analysis revealed to have a seasonal dependence in both aspects: the duration of positive excursion along the day and the maximum amplitude. And the other components have also shown remarkable regional characteristic of the variation of the Sq. Finally, we take these results as the first steps towards developing a Sq model to be superimposed to International Geomagnetic Reference Field (IGRF) model as a useful tool for space weather forecast.

  2. Solar wind ˜0.1-1.5 keV electrons at quiet times

    NASA Astrophysics Data System (ADS)

    Tao, Jiawei; Wang, Linghua; Zong, Qiugang; Li, Gang; Salem, Chadi S.; Wimmer-Schweingruber, Robert F.; He, Jiansen; Tu, Chuanyi; Bale, Stuart D.

    2016-03-01

    We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3-D Plasma & Energetic Particle (3DP) instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. Firstly, we separate strahl (beaming) electrons and halo (isotropic) electrons based on their features in pitch angle distributions. Secondly, we fit the observed energy spectrum of both the strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ, effective temperature Teff and density n0. We also integrate the the measurements over ˜0.1-1.5 keV to obtain the average electron energy Eavg of the strahl and halo. We find a strong positive correlation between κ and Teff for both the strahl and halo, possibly reflecting the nature of the generation of these suprathermal electrons. Among the 245 selected samples, ˜68% have the halo κ smaller than the strahl κ, while ˜50% have the halo Eh larger than the strahl Es.

  3. ON QUIET-TIME SOLAR WIND ELECTRON DISTRIBUTIONS IN DYNAMICAL EQUILIBRIUM WITH LANGMUIR TURBULENCE

    SciTech Connect

    Zaheer, S.; Yoon, P. H.

    2013-10-01

    A recent series of papers put forth a self-consistent theory of an asymptotically steady-state electron distribution function and Langmuir turbulence intensity. The theory was developed in terms of the κ distribution which features Maxwellian low-energy electrons and a non-Maxwellian energetic power-law tail component. The present paper discusses a generalized κ distribution that features a Davydov-Druyvesteyn type of core component and an energetic power-law tail component. The physical motivation for such a generalization is so that the model may reflect the influence of low-energy electrons interacting with low-frequency kinetic Alfvénic turbulence as well as with high-frequency Langmuir turbulence. It is shown that such a solution and the accompanying Langmuir wave spectrum rigorously satisfy the balance requirement between the spontaneous and induced emission processes in both the particle and wave kinetic equations, and approximately satisfy the similar balance requirement between the spontaneous and induced scattering processes, which are nonlinear. In spite of the low velocity modification of the electron distribution function, it is shown that the resulting asymptotic velocity power-law index α, where f{sub e} ∼ v {sup –α} is close to the average index observed during the quiet-time solar wind condition, i.e., α ∼ O(6.5) whereas α{sub average} ∼ 6.69, according to observation.

  4. Explaining Inverted Temperature Loops in the Quiet Solar Corona with Magnetohydrodynamic Wave Mode Conversion

    NASA Astrophysics Data System (ADS)

    Schiff, Avery; Cranmer, Steven R.

    2016-05-01

    We simulate the temperature profiles along coronal loops measured with AIA DEM tomography and field-line extrapolation by Nuevo et al (2013). By varying the strength and nature of the heating mechanism, we modeled steady-state, gravitationally stable loops that have temperature profiles with local maxima below the loop apex. Because these loops have negative vertical temperature gradients over much of their length, they have been called "down loops" and were seen to exist primarily in equatorial quiet regions near solar minimum. In our models, the amount of heat deposited in the loop is attributed to two sources: (1) the dissipation of Alfven waves in a turbulent cascade, and (2) the dissipation of compressive waves over a variable length. The compressive waves are generated in a nonlinear process by which some fraction of the Alfven waves undergo mode conversion instead of contributing directly to the heating process. We found that when a large percentage (> 99%) of the Alfven waves underwent this conversion, the heating was greatly concentrated at the base of the loop and stable "down loops" were created. In some cases, we found loops with three extrema that are gravitationally stable. We map the full parameter space to explore which conditions lead to which loop types, and we demonstrate that the simulated characteristics of the loops -- including magnetic field strength, pressure, and temperature -- are consistent with values measured by Nuevo et al. (2013).

  5. Small Scale Dynamo Magnetism And the Heating of the Quiet Sun Solar Atmosphere.

    NASA Astrophysics Data System (ADS)

    Amari, T.

    2015-12-01

    The longstanding problem of the solar atmosphere heating has been addressed by many theoretical studies. Two specific mechanisms have been shown to play a key role in those : magnetic reconnection and waves. On the other hand the necessity of treating together chromosphere and corona has also been been stressed, with debates going on about the possibility of heating coronal plasma by energetic phenomena observed in the chromosphere,based on many key observations such as spicules, tornadoes…. We present some recent results about the modeling of quiet Sun heating in which magnetic fields are generated by a subphotospheric fluid dynamo which is connected to granulation. The model shows a topologically complex magnetic field of 160 G on the Sun's surface, agreeing with inferences obtained from spectropolarimetric observations.Those generated magnetic fields emerge into the chromosphere, providing the required energy flux and then small-scale eruptions releasing magnetic energy and driving sonic motions. Some of the more energetic eruptions can affect the very low corona only.It is also found that taking into account a vertical weak network magnetic field then allows to provide energy higher in the corona, while leaving unchanged the physics of chromospheric eruptions. The coronal heating mechanism rests on the eventual dissipation of Alfven waves generated inside the chromosphere and carrying upwards an adequate energy flux, while more energetic phenomena contribute only weakly to the heating of the corona.

  6. NEWLY DISCOVERED GLOBAL TEMPERATURE STRUCTURES IN THE QUIET SUN AT SOLAR MINIMUM

    SciTech Connect

    Huang Zhenguang; Frazin, Richard A.; Landi, Enrico; Manchester, Ward B.; Gombosi, Tamas I.; Vasquez, Alberto M.

    2012-08-20

    Magnetic loops are building blocks of the closed-field corona. While active region loops are readily seen in images taken at EUV and X-ray wavelengths, quiet-Sun (QS) loops are seldom identifiable and are therefore difficult to study on an individual basis. The first analysis of solar minimum (Carrington Rotation 2077) QS coronal loops utilizing a novel technique called the Michigan Loop Diagnostic Technique (MLDT) is presented. This technique combines Differential Emission Measure Tomography and a potential field source surface (PFSS) model, and consists of tracing PFSS field lines through the tomographic grid on which the local differential emission measure is determined. As a result, the electron temperature T{sub e} and density N{sub e} at each point along each individual field line can be obtained. Using data from STEREO/EUVI and SOHO/MDI, the MLDT identifies two types of QS loops in the corona: so-called up loops in which the temperature increases with height and so-called down loops in which the temperature decreases with height. Up loops are expected, however, down loops are a surprise, and furthermore, they are ubiquitous in the low-latitude corona. Up loops dominate the QS at higher latitudes. The MLDT allows independent determination of the empirical pressure and density scale heights, and the differences between the two remain to be explained. The down loops appear to be a newly discovered property of the solar minimum corona that may shed light on the physics of coronal heating. The results are shown to be robust to the calibration uncertainties of the EUVI instrument.

  7. Quiet-time properties of low-energy (less than 10 MeV per nucleon) interplanetary ions during solar maximum and solar minimum

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Reames, D. V.; Wenzel, K.-P.; Rodriguez-Pacheco, J.

    1990-01-01

    The abundances and spectra of 1-10 MeV per nucleon protons, He-3, He-4, C, O, and Fe have been exmained during solar quiet periods from 1978 to 1987 in an effort to investigate the recent suggestion by Wenzel et al. (1990) that the ions may be of solar origin. It is found that the intensities of the ions, other than O, fall by an order of magnitude between solar maximum and solar minimum, and that the greater than 1 MeV per nucleon ions exhibit weak streaming away from the sun. More significantly, the quiet-time ions during solar maximum have He-3-rich and Fe-rich abundances which are established characteristics of small impulsive solar flares. Thus, it is suggested that small unresolved impulsive flares make a substantial contribution to the 'quiet-time' fluxes. He-4 from these flares may also contribute strongly to the ion spectra that were reported for the 35-1600 keV energy range by Wenzel et al.

  8. Heliospheric and geomagnetic modulation of galactic cosmic rays under quiet and disturbed interplanetary conditions during solar cycles 20-23

    NASA Astrophysics Data System (ADS)

    Chukwudi Okpala, Kingsley

    2015-08-01

    The modulation of galactic cosmic rays (GCR) within the heliosphere leads to a reduction in the GCR count rates during period of high solar activity and conversely. Data from three geomagnetic observatories and three Neutron monitors (in close proximity to the geomagnetic stations) have been studied. The monthly residuals of the geomagnetic field components with respect to quiet time conditions from these three stations have been computed and compared with the cosmic ray count rates. The modulations of the GCR during quiet and disturbed interplanetary conditions have been investigated with a view to better understand the role of the global merged interaction regions and intense magnetic fields to the GCR modulation. From first-order partial correlation, we found that removing the influence of the total IMF-B, (especially during quiet conditions) and the influence of SW dynamic pressure (during disturbed conditions) generally enhances the correlation of the residual geomagnetic field with the GCR significantly. The influence of the more subtle parameters like speed, Bz component and proton density were masked by these dominant parameters. Results from this work are important for the modeling of long term GCR variability.

  9. Pole-equator difference and the variability of the brightness of the chromospheric CaII-K-network elements in quiet regions over the solar cycle

    NASA Technical Reports Server (NTRS)

    Kariyappa, R.

    1995-01-01

    The dependence of the brightness of chromospheric network elements on latitude was investigated for quiet solar regions. Calibrated photographic CaII K-spectroheliograms were used to compare the variation in brightness at the center of the disk with higher latitude of chromospheric network elements in a quiet region as a function of solar activity. It was found that there was no significant difference in brightness between the center of the solar disk and higher latitude. It is concluded that the brightness of the chromospheric network elements in a quiet region does not depend on the latitude, but that the variation in the intensity enhancement is related to the level of solar activity.

  10. Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

    NASA Technical Reports Server (NTRS)

    Moon, S.; Simnett, G. M.; White, R. S.

    1975-01-01

    The UCR large area solid-angle double scatter neutron telescope was flown to search for solar neutrons on 3 balloon flights on September 26, 1971, May 14, 1972 and September 19, 1972. The first two flights were launched from Palestine, Texas and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet time solar neutron fluxes at the 95% confidence level are .00028, .00046, .00096 and .00090 neutrons/sq cm-sec in the energy intervals of 10-30, 30-50, 50-100 and 10-100 MeV, respectively.

  11. Correlation lifetimes of quiet and magnetic granulation from the SOUP instrument on Spacelab 2. [Solar Optical Universal Polarimeter

    NASA Technical Reports Server (NTRS)

    Title, A.; Tarbell, T.; Topka, K.; Acton, L.; Duncan, D.

    1988-01-01

    The time sequences of diffraction limited granulation images obtained by the Solar Optical Universal Polarimeter on Spacelab 2 are presented. The uncorrection autocorrelation limetime in magnetic regions is dominated by the 5-min oscillation. The removal of this oscillation causes the autocorrelation lifetime to increase by more than a factor of 2. The results suggest that a significant fraction of granule lifetimes are terminated by nearby explosions. Horizontal displacements and transverse velocities in the intensity field are measured. Lower limits to the lifetime in the quiet and magnetic sun are set at 440 s and 950 s, respectively.

  12. Quiet-time Suprathermal (~0.1-1.5 keV) Electrons in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Tao, Jiawei; Wang, Linghua; Zong, Qiugang; Li, Gang; Salem, Chadi S.; Wimmer-Schweingruber, Robert F.; He, Jiansen; Tu, Chuanyi; Bale, Stuart D.

    2016-03-01

    We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity).

  13. Long-term variation in the ionosphere and lower thermosphere as seen in the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Hori, T.; Nose, M.; Otsuka, Y.

    2015-12-01

    In order to investigate characteristics of the long-term variation in the ionosphere and lower thermosphere, we analyzed the amplitude of geomagnetic solar quiet (Sq) field daily variation using 1-h geomagnetic field data obtained from 69 geomagnetic stations within the period of 1947-2013. In the present data analysis, we took advantage of the Inter-university Upper atmosphere Global Observation NETwork (IUGONET) products (metadata database and analysis software) for finding and handling the long-term observation data obtained at many observatories. The Sq amplitude observed at these geomagnetic stations showed a clear solar activity dependence and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008-2009. This significant depression implies that the solar extreme ultraviolet (EUV) radiation responsible for ionization of the upper atmosphere decreased during this solar cycle minimum. In order to examine a global distribution of the long-term trend in the Sq amplitude, we derived the residual Sq amplitude from the deviation from the fitting curve between the solar F10.7 index and Sq amplitude. As a result, a majority of the trends in the residual Sq amplitude showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. Moreover, we estimate the neutral wind in the lower thermosphere from the Sq amplitude and height-integrated ionospheric conductivity in order to know the physical mechanism of the long-term trend in the residual Sq amplitude. As a result, the estimated thermospheric zonal and meridional winds showed a seasonal variation with a period of one year or less, but the solar activity dependence was unclear. This result suggests that the solar cycle dependence of the Sq amplitude may be mainly attributed to the variation of the ionospheric conductivity.

  14. The dynamic quiet solar corona: 4 days of joint observing with MDI and EIT

    NASA Technical Reports Server (NTRS)

    Schrijver, C. J.; Shine, R. A.; Hurlburt, N. E.; Tarbell, T. D.; Lemen, J. R.

    1997-01-01

    The analysis of a sequence of joint extreme ultraviolet imaging telescope (EIT) Fe XII and Michelson Doppler imager (MDI) magnetogram observations of the quiet sun near disk center is presented. It was found that: all the emerging flux above the threshold of approximately 10(sup 17) Mx is associated with enhanced coronal emissions; loop systems between the polarities in ephemeral regions remain visible up to separations of 10000 up to 30000 km; brightenings between approaching opposite polarity network concentrations form when the concentrations are between 5000 and 25000 km apart, and that faint connections up to 40000 km in length form as sets of concentrations of the same polarity coagulate. The coronal emission over patches of the quiet sun depends on the total flux in connected concentrations, on their distance and on the positions and strengths of neighboring concentrations.

  15. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, Atsuki; Koyama, Yukinobu; Nose, Masahito; Hori, Tomoaki; Otsuka, Yuichi; Yatagai, Akiyo

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet (Sq) geomagnetic field daily variation have been investigated using 1-h geomagnetic field data obtained from 69 geomagnetic observation stations within the period of 1947 to 2013. The Sq amplitude observed at these geomagnetic stations showed a clear dependence on the 10- to 12-year solar activity cycle and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008 to 2009. The relationship between the solar F10.7 index and Sq amplitude was approximately linear but about 53% of geomagnetic stations showed a weak nonlinear relation to the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second-order fitting curve between the solar F10.7 index and Sq amplitude during 1947 to 2013 and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, the majority of trends in the residual Sq amplitude that passed through a trend test showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity at 100-km altitude and residual Sq amplitude showed an anti-correlation for about 71% of the geomagnetic stations. Furthermore, the residual Sq amplitude at the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

  16. Changes of intranetwork and internetwork functional connectivity in Alzheimer’s disease and mild cognitive impairment

    NASA Astrophysics Data System (ADS)

    Zhu, Haoze; Zhou, Peng; Alcauter, Sarael; Chen, Yuanyuan; Cao, Hongbao; Tian, Miao; Ming, Dong; Qi, Hongzhi; Wang, Xuemin; Zhao, Xin; He, Feng; Ni, Hongyan; Gao, Wei

    2016-08-01

    Objective. Alzheimer’s disease (AD) is a serious neurodegenerative disorder characterized by deficits of working memory, attention, language and many other cognitive functions. Although different stages of the disease are relatively well characterized by clinical criteria, stage-specific pathological changes in the brain remain relatively poorly understood, especially at the level of large-scale functional networks. In this study, we aimed to characterize the potential disruptions of large-scale functional brain networks based on a sample including amnestic mild cognition impairment (aMCI) and AD patients to help delineate the underlying stage-dependent AD pathology. Approach. We sought to identify the neural connectivity mechanisms of aMCI and AD through examination of both intranetwork and internetwork interactions among four of the brain’s key networks, namely dorsal attention network (DAN), default mode network (DMN), executive control network (ECN) and salience network (SAL). We analyzed functional connectivity based on resting-state functional magnetic resonance imaging (rs-fMRI) data from 25 Alzheimer’s disease patients, 20 aMCI patients and 35 elderly normal controls (NC). Main results. Intranetwork functional disruptions within the DAN and ECN were detected in both aMCI and AD patients. Disrupted intranetwork connectivity of DMN and anti-correlation between DAN and DMN were observed in AD patients. Moreover, aMCI-specific alterations in the internetwork functional connectivity of SAL were observed. Significance. Our results confirmed previous findings that AD pathology was related to dysconnectivity both within and between resting-state networks but revealed more spatial details. Moreover, the SAL network, reportedly flexibly coupling either with the DAN or DMN networks during different brain states, demonstrated interesting alterations specifically in the early stage of the disease.

  17. Observations of low energy hydrogen and helium isotopes during solar quiet times

    NASA Technical Reports Server (NTRS)

    Hurford, G. J.; Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1974-01-01

    Results of a new quiet-time measurement of the relative abundance of cosmic-ray H-2 and He-4. The observations were made in selected time intervals between September 1972 and February 1973 with the Caltech Electron/Isotope Spectrometer on IMP-7. In the energy interval from 13 to 29 MeV/nucleon, an upper limit to the H-2 to He-4 ratio of less than 0.06 is found. This new upper limit is significantly lower than finite H-2/He-4 ratios measured in earlier years by other workers. Possible implications of this new result are discussed.

  18. Comparison of physical properties of quiet and active regions through the analysis of magnetohydrodynamic simulations of the solar photosphere

    SciTech Connect

    Criscuoli, S.

    2013-11-20

    Recent observations have shown that the photometric and dynamic properties of granulation and small-scale magnetic features depend on the amount of magnetic flux of the region they are embedded in. We analyze results from numerical hydrodynamic and magnetohydrodynamic simulations characterized by different amounts of average magnetic flux and find qualitatively the same differences as those reported from observations. We show that these different physical properties result from the inhibition of convection induced by the presence of the magnetic field, which changes the temperature stratification of both quiet and magnetic regions. Our results are relevant for solar irradiance variations studies, as such differences are still not properly taken into account in irradiance reconstruction models.

  19. Observations of high-energy jets in the corona above the quiet sun, the heating of the corona, and the acceleration of the solar wind

    NASA Technical Reports Server (NTRS)

    Brueckner, G. E.; Bartoe, J.-D. F.

    1983-01-01

    High spatial resolution observations of the ultraviolet solar spectrum which reveal high-energy events in the quiet sun are presented. The tandem Wadsworth spectrograph used to make the observations is described along with the observing techniques, and a brief description of the characteristics of high-resolution transition zone spectra is given. The sizes, velocities, line profiles, time behavior, temperature range, differential emission measures, densities, masses, energies, and birthrates of turbulent events and jets in the quiet sun are derived from the observations and discussed. Possible accelerating mechanisms for these events are discussed, and the consequences of these events for the heating of the solar corona are discussed. A cloud model of the solar wind is proposed and possible correlations between the high-energy events and other solar fine-structure features are discussed.

  20. CORONAL HEATING BY THE INTERACTION BETWEEN EMERGING ACTIVE REGIONS AND THE QUIET SUN OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY

    SciTech Connect

    Zhang, Jun; Zhang, Bin; Li, Ting; Yang, Shuhong; Zhang, Yuzong; Li, Leping; Chen, Feng; Peter, Hardi E-mail: liting@nao.cas.cn E-mail: yuzong@nao.cas.cn E-mail: chen@mps.mpg.de

    2015-02-01

    The question of what heats the solar corona remains one of the most important puzzles in solar physics and astrophysics. Here we report Solar Dynamics Observatory Atmospheric Imaging Assembly observations of coronal heating by the interaction between emerging active regions (EARs) and the surrounding quiet Sun (QS). The EARs continuously interact with the surrounding QS, resulting in dark ribbons which appear at the boundary of the EARs and the QS. The dark ribbons visible in extreme-ultraviolet wavelengths propagate away from the EARs with speeds of a few km s{sup −1}. The regions swept by the dark ribbons are brightening afterward, with the mean temperature increasing by one quarter. The observational findings demonstrate that uninterrupted magnetic reconnection between EARs and the QS occurs. When the EARs develop, the reconnection continues. The dark ribbons may be the track of the interface between the reconnected magnetic fields and the undisturbed QS’s fields. The propagating speed of the dark ribbons reflects the reconnection rate and is consistent with our numerical simulation. A long-term coronal heating which occurs in turn from nearby the EARs to far away from the EARs is proposed.

  1. Altered Intranetwork and Internetwork Functional Connectivity in Type 2 Diabetes Mellitus With and Without Cognitive Impairment.

    PubMed

    Yang, Shi-Qi; Xu, Zhi-Peng; Xiong, Ying; Zhan, Ya-Feng; Guo, Lin-Ying; Zhang, Shun; Jiang, Ri-Feng; Yao, Yi-Hao; Qin, Yuan-Yuan; Wang, Jian-Zhi; Liu, Yong; Zhu, Wen-Zhen

    2016-01-01

    Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment. We investigated whether alterations of intranetwork and internetwork functional connectivity with T2DM progression exist, by using resting-state functional MRI. MRI data were analysed from 19 T2DM patients with normal cognition (DMCN) and 19 T2DM patients with cognitive impairment (DMCI), 19 healthy controls (HC). Functional connectivity among 36 previously well-defined brain regions which consisted of 5 resting-state network (RSN) systems [default mode network (DMN), dorsal attention network (DAN), control network (CON), salience network (SAL) and sensorimotor network (SMN)] was investigated at 3 levels (integrity, network and connectivity). Impaired intranetwork and internetwork connectivity were found in T2DM, especially in DMCI, on the basis of the three levels of analysis. The bilateral posterior cerebellum, the right insula, the DMN and the CON were mainly involved in these changes. The functional connectivity strength of specific brain architectures in T2DM was found to be associated with haemoglobin A1c (HbA1c), cognitive score and illness duration. These network alterations in intergroup differences, which were associated with brain functional impairment due to T2DM, indicate that network organizations might be potential biomarkers for predicting the clinical progression, evaluating the cognitive impairment, and further understanding the pathophysiology of T2DM. PMID:27622870

  2. The quiet time spectra of low energy hydrogen and helium nuclei. [suggesting protons and alphas of solar origin

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1975-01-01

    Measurements of the 1972-1973 quiet time hydrogen and helium spectra from 1.3-40 MeV/nuc are discussed. For both spectra the relative-intensity minimum occurs at lower energies than those reported for earlier years. There is no evidence of a low energy turnup in the He spectrum down to 2.4 MeV/nuc. The spectra indicate that the galactic component dominates down to about 10 MeV; a stable, non-solar He-4 component extends from higher energies down to about 2.4 MeV/nuc. At lower energies the periods of minimum H and He intensity do not coincide, and the relative abundance of H and He at 1.3-2.3 MeV/nuc is variable, with H/He ratios ranging from about 3 to about 10. The observations suggest that the 1.3-2.3 MeV/nuc protons and alphas are of solar origin.

  3. Wave propagation in a solar quiet region and the influence of the magnetic canopy

    NASA Astrophysics Data System (ADS)

    Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

    2016-01-01

    Aims: We seek indications or evidence of transmission/conversion of magnetoacoustic waves at the magnetic canopy, as a result of its impact on the properties of the wave field of the photosphere and chromosphere. Methods: We use cross-wavelet analysis to measure phase differences between intensity and Doppler signal oscillations in the Hα, Ca ii h, and G-band. We use the height of the magnetic canopy to create appropriate masks to separate internetwork (IN) and magnetic canopy regions. We study wave propagation and differences between these two regions. Results: The magnetic canopy affects wave propagation by lowering the phase differences of progressive waves and allowing the propagation of waves with frequencies lower than the acoustic cut-off. We also find indications in the Doppler signals of Hα of a response to the acoustic waves at the IN, observed in the Ca ii h line. This response is affected by the presence of the magnetic canopy. Conclusions: Phase difference analysis indicates the existence of a complicated wave field in the quiet Sun, which is composed of a mixture of progressive and standing waves. There are clear imprints of mode conversion and transmission due to the interaction between the p-modes and small-scale magnetic fields of the network and internetwork.

  4. PHYSICAL PROPERTIES OF LARGE AND SMALL GRANULES IN SOLAR QUIET REGIONS

    SciTech Connect

    Yu Daren; Xie Zongxia; Hu Qinghua; Yang Shuhong; Zhang Jun; Wang Jingxiu E-mail: zjun@ourstar.bao.ac.cn

    2011-12-10

    The normal mode observations of seven quiet regions obtained by the Hinode spacecraft are analyzed to study the physical properties of granules. An artificial intelligence technique is introduced to automatically find the spatial distribution of granules in feature spaces. In this work, we investigate the dependence of granular continuum intensity, mean Doppler velocity, and magnetic fields on granular diameter. We recognized 71,538 granules by an automatic segmentation technique and then extracted five properties: diameter, continuum intensity, Doppler velocity, and longitudinal and transverse magnetic flux density to describe the granules. To automatically explore the intrinsic structures of the granules in the five-dimensional parameter space, the X-means clustering algorithm and one-rule classifier are introduced to define the rules for classifying the granules. It is found that diameter is a dominating parameter in classifying the granules and two families of granules are derived: small granules with diameters smaller than 1.''44, and large granules with diameters larger than 1.''44. Based on statistical analysis of the detected granules, the following results are derived: (1) the averages of diameter, continuum intensity, and Doppler velocity in the upward direction of large granules are larger than those of small granules; (2) the averages of absolute longitudinal, transverse, and unsigned flux density of large granules are smaller than those of small granules; (3) for small granules, the average of continuum intensity increases with their diameters, while the averages of Doppler velocity, transverse, absolute longitudinal, and unsigned magnetic flux density decrease with their diameters. However, the mean properties of large granules are stable; (4) the intensity distributions of all granules and small granules do not satisfy Gaussian distribution, while that of large granules almost agrees with normal distribution with a peak at 1.04 I{sub 0}.

  5. Spatial and Temporal Variations of Solar Quiet Daily Sq Variation and Equatorial Electrojet Over Africa: Results From International Heliophysical Year

    NASA Astrophysics Data System (ADS)

    Rabiu, A.; Yumoto, K.; Bello, O.

    2010-12-01

    Space Environment Research Centre of Kyushu University, Japan, installed 13 units of Magnetic Data Acquisition Systems MAGDAS over Africa during the International Heliophysical Year IHY. Magnetic records from 10 stations along the African 96o Magnetic Meridian (Geographical 30o - 40o East) were examined for Solar quiet daily Sq variation in the three geomagnetic field components H, D and Z. Spatial variations of Sq in the geomagnetic components were examined. Signatures of equatorial electrojet and worldwide Sq were identified and studied in detail. H field experienced more variation within the equatorial electrojet zone. Diurnal and seasonal variations of the geomagnetic variations in the three components were discussed. Levels of inter-relationships between the Sq and its variability in the three components were statistically derived and interpreted in line with the mechanisms responsible for the variations of the geomagnetic field. Data from 2 magnetic observatories within equatorial electrojet EEJ strip and 2 stations outside the EEJ strip were employed to evaluate and study the signatures of the Equatorial electrojet over the African sector. The transient variations of the EEJ at two almost parallel axes using Lagos-Ilorin and Nairobi-Addis pairs were examined. The EEJ appear stronger in East than West Africa. The magnitudes and patterns of variation of EEJ strength along the two axes were examined for any simultaneity or otherwise of responses to ionospheric processes. The flow gradient of EEJ along the African sector was estimated and its diurnal variation studied.

  6. Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

    NASA Technical Reports Server (NTRS)

    Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

    1988-01-01

    The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

  7. MESSENGER soft X-ray observations of the quiet solar corona

    NASA Astrophysics Data System (ADS)

    Schwartz, Richard A.; Hudson, Hugh S.; Tolbert, Anne K; Dennis, Brian R.

    2014-06-01

    In a remarkable result from their "SphinX" experiment, Sylwester et al. (2012) found a non-varying base level of soft X-ray emission at the quietest times in 2009. We describe comparable data from the soft X-ray monitor on board MESSENGER (en route to Mercury) which had excellent coverage both in 2009 and during the true solar minimum of 2008. These observations overlap SphinX's and also are often exactly at Sun-MESSENGER-Earth conjunctions. During solar minimum the Sun-MESSENGER distance varied substantially, allowing us to use the inverse-square law to help distinguish the aperture flux (ie, solar X-rays) from that due to sources of background in the 2-5 keV range. The MESSENGER data show a non-varying background level for many months in 2008 when no active regions were present. We compare these data in detail with those from SphinX. Both sets of data reveal a different behavior when magnetic active regions are present on the Sun, and when they are not.Reference: Sylwester et al., ApJ 751, 111 (2012)

  8. Long-term variation in the upper atmosphere as seen in the amplitude of the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Hayashi, H.; Nose, M.; Hori, T.; Otsuka, Y.; Tsuda, T.

    2011-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by global ionospheric currents flowing in the E-region from middle latitudes to the magnetic equator. These currents are generated by a dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the thermosphere and ionosphere. From the Ohm's equation, the ionospheric currents strongly depend on the ionospheric conductivity, polarization electric field and neutral wind. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the thermosphere and ionosphere. Elias et al. [2010] found that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes from 1961 to 2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is ionospheric conductivity enhancement associated with cooling effects in the thermosphere due to increasing the greenhouse gases. In this talk, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. These observation data have been provided by the IUGONET (Inter-university Upper atmosphere Global Observation NETwork) project. In the present analysis, we used the F10.7 flux as an indicator of the variation in the solar irradiance in the EUV and UV range, geomagnetic field data with time resolution of 1 hour. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum per day when the Kp index is less than 4. As a result, the Sq amplitude at all the stations strongly depends on 11-year solar activity, and tends to enhance more during the high activities (19- and 22- solar cycles) than during the low activity (20-solar cycle). The Fourier spectra of the F10.7 flux and Sq

  9. Quiet Ride

    ERIC Educational Resources Information Center

    Rathey, Allen

    2006-01-01

    Several companies are marketing maintenance equipment to education institutions on a "quiet platform," citing benefits such as a safer, more pleasant indoor environment and unobtrusive operations during day cleaning or operating hours. This is basically "sound advice" (no one likes noisy equipment), but some of the messages can be confusing and…

  10. The Temperature and Density Structure of the Solar Corona. I. Observations of the Quiet Sun with the EUV Imaging Spectrometer on Hinode

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Brooks, David H.

    2009-07-01

    Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations of current atomic calculations, particularly those for Fe, all conspire to make this task very difficult. A critical assessment of plasma diagnostics in the corona is essential to making progress on the coronal heating problem. In this paper, we present an analysis of temperature and density measurements above the limb in the quiet corona using new observations from the EUV Imaging Spectrometer (EIS) on Hinode. By comparing the Si and Fe emission observed with EIS we are able to identify emission lines that yield consistent emission measure distributions. With these data we find that the distribution of temperatures in the quiet corona above the limb is strongly peaked near 1 MK, consistent with previous studies. We also find, however, that there is a tail in the emission measure distribution that extends to higher temperatures. EIS density measurements from several density sensitive line ratios are found to be generally consistent with each other and with previous measurements in the quiet corona. Our analysis, however, also indicates that a significant fraction of the weaker emission lines observed in the EIS wavelength ranges cannot be understood with current atomic data.

  11. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet (Sq) daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Yatagai, A. I.; Nose, M.; Hori, T.; Otsuka, Y.

    2012-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by the global ionospheric currents flowing in the E-region, which are generated by dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the lower thermosphere and ionosphere. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the lower thermosphere and ionosphere. Recently, Elias et al. [2010] reported that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes in a period of 1961-2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is due to ionospheric conductivity enhancement associated with cooling effect in the thermosphere due to increasing greenhouse gas. In the present study, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. In the present analysis, we used the F10.7 solar flux as a good indicator of the variation in the solar irradiance in the EUV and UV range as well as geomagnetic field data with time resolution of 1 hour observed at 184 geomagnetic stations. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum every day when the Kp index is less than 4. As a result, the long-term variation in the Sq amplitude at all the geomagnetic stations shows a strong correlation with the solar F10.7 flux which depends on 11-year solar activity. The relationship between the Sq amplitude and F10.7 flux was not linear but nonlinear. This nonlinearity could be interpreted as the decrease of production rate of electrons and ions in the ionosphere for the strong EUV and UV fluxes as already reported by Balan et al. [1993]. In order to minimize the solar

  12. Determination of Geomagnetically Quiet Time Disturbances of the Ionosphere over Uganda during the Beginning of Solar Cycle

    NASA Astrophysics Data System (ADS)

    Habyarimana, Valence

    2016-07-01

    The ionosphere is prone to significant disturbances during geomagnetically active and quiet conditions. This study focused on the occurrence of ionospheric disturbances during geomagnetically quiet conditions. Ionospheric data comprised of Global Positioning System (GPS)-derived Total Electron Content (TEC), obtained over Mt. Baker, Entebbe, and Mbarara International Global Navigation Satellite System (GNSS) Service (IGS) stations. The Disturbance storm time (Dst) index was obtained from Kyoto University website. The number of geomagnetically quiet days in the period under study were first identified. Their monthly percentages were compared for the two years. The monthly percentage of geomagnetically quiet days for all the months in 2009 numerically exceeded those in 2008. December had the highest percentage of geomagnetically quiet days for both years (94 % in 2008 and 100 % in 2009). Geomagnetically quiet days did not show seasonal dependence. The variation in percentage of geomagnetically quiet days during solstice months (May, June, July, November, December, and January) and equinoctial months (February, March, April, August, September, and October) was not uniform. Geomagnetically quiet time disturbances were found to be more significant from 09:00 UT to 13:00 UT. However, there were some other disturbances of small scale amplitude that occurred between 14:00 UT and 22:00 UT. Further analysis was done to identify the satellites that observed the irregularities that were responsible for TEC perturbations. Satellites are identified by Pseudo Random Numbers (PRNs). The ray path between individual PRNs and the corresponding receivers were analysed. Satellites with PRNs: 3, 7, 8, 19 and 21 registered most of the perturbations. It was found that Q disturbances led to fluctuations in density gradients. Significant TEC perturbations were observed on satellite with PRN 21 with receivers at Entebbe and Mbarara on June 28, 2009 between 18:00 UT and 21:00 UT.

  13. NEW Fe IX LINE IDENTIFICATIONS USING SOLAR AND HELIOSPHERIC OBSERVATORY/SOLAR ULTRAVIOLET MEASUREMENT OF EMITTED RADIATION AND HINODE/EIS JOINT OBSERVATIONS OF THE QUIET SUN

    SciTech Connect

    Landi, E.; Young, P. R.

    2009-12-20

    In this work, we study joint observations of Hinode/EUV Imaging Spectrometer (EIS) and Solar and Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation of Fe IX lines emitted by the same level of the high energy configuration 3s {sup 2}3p {sup 5}4p. The intensity ratios of these lines are dependent on atomic physics parameters only and not on the physical parameters of the emitting plasma, so that they are excellent tools to verify the relative intensity calibration of high-resolution spectrometers that work in the 170-200 A and 700-850 A wavelength ranges. We carry out extensive atomic physics calculations to improve the accuracy of the predicted intensity ratio, and compare the results with simultaneous EIS-SUMER observations of an off-disk quiet Sun region. We were able to identify two ultraviolet lines in the SUMER spectrum that are emitted by the same level that emits one bright line in the EIS wavelength range. Comparison between predicted and measured intensity ratios, wavelengths and energy separation of Fe IX levels confirms the identifications we make. Blending and calibration uncertainties are discussed. The results of this work are important for cross-calibrating EIS and SUMER, as well as future instrumentation.

  14. Mapping the earth conductivity-depth structure of African geomagnetic equatorial anomaly regions using solar quiet current variations

    NASA Astrophysics Data System (ADS)

    Ugbor, D. O.; Okeke, F. N.; Yumoto, K.

    2016-04-01

    The solar quiet day ionospheric (Sq) current variations observed in Abuja, Bangui and Addis Ababa were used to delineate the mantle conductivity-depth structure along the equatorial African regions. Spherical harmonic analysis (SHA) was employed in separating the internal and external field contributions to the Sq variations. For each of the paired external and internal coefficients of the SHA, we used transfer function to compute the conductivity-depth profile for the region. Strikingly, we observed increased electrical conductivity values in the Earth layers and deep depth penetration. The calculated average electrical conductivity values in Addis Ababa and Abuja are 0.087 Sm-1 and 0.104 Sm-1 at depths of 93 km and 121 km respectively. These values suddenly rose to 0.235 Sm-1 and 0.222 Sm-1 at depths of 440 km and 427 km respectively. In Bangui, the calculated average values are 0.092 Sm-1, 0.144 Sm-1, 0.312 Sm-1 and 0.466 Sm-1 at 96 km, 300 km, 834 km and 1228 km depths respectively. At the greatest depths of penetration of 1412 km, 1385 km and 1278 km in Addis Ababa, Abuja and Bangui, the electrical conductivity attained the highest values of 0.415 Sm-1, 0.467 Sm-1 and 0.515 Sm-1 respectively. Two most Earth conductive layers were discovered in the magnetic equatorial zone. These layers lie between the depth of about 100 and 400 km within the upper mantle and beyond 1200 km in the lower mantle. It can be inferred that the closer one goes towards the Earth magnetic equator; the deeper the Sq current can penetrate the Earth's interior.

  15. Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles

    NASA Astrophysics Data System (ADS)

    Balachandra Swamy, A. C.

    EXTENDED ABSTRACT Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles A.C.Balachandra swmay & Late C.S.G.K. Setty Absorption of radio waves in the ionosphere is of great practical importance for radio communication and navigation systems. The first attempt to measure the absolute magnitude of the radiowave absorption were made by appletion and Ratcliffe (1930) using the frequency change method for medium frequency waves reflected from the E-region. They concluded from their experiment that the main part of the attenuation occurred below the reflection level and named the absorption region, D-region of the ionosphere. One of the basic properties of the ionosphere is the absorption of high Frequency Radiowaves. HF radiowave absorption results mainly from collisions between electrons (which are set into forced oscillations by the electric field of the wave) and neutral air particles, the RF energy abstracted from the wave being converted into thermal energy. The radiowave absorption in the ionosphere depends on electron density and collision frequency. The most important absorbing regions are the D-region and the lower E-region (50-100 Km.) The regular diurnal variation of the electron density in this height range is caused mainly by the changes in the depth of penetration of solar XUV radiations with solar zenith angle under quiet solar conditions. In 1937 Dellinger J.H.identified fade outs in high frequency radio circuits as due to abnormal ionospheric absorption associated with solar flares. The onset of the fade out was usually rapid and the duration was typically tens of minutes like that of the visible flare, because of the sudden onset, the immediate effects of solar flares are known collectively as sudden Ionospheric Disturbances (STD). The phenomenon discovered by Dellinger is usually called a short Wave Fadeout(SWF). Since the SWF is due to abnormal absorption

  16. The seasonal and solar cycle variations of electron density gradient scale length, vertical drift and layer height during magnetically quiet days: Implications for Spread F over Trivandrum, India

    NASA Astrophysics Data System (ADS)

    Manju, G.; Devasia, C. V.; Ravindran, S.

    2009-12-01

    A study has been carried out on the behaviour of electron density gradient scale length, L, vertical drift and layer height, around post sunset hours, during the magnetically quiet days of summer, winter and equinox seasons of solar maximum (2002) and minimum years (1995), using ionosonde data of Trivandrum (8.5°N, 76.5°E, dip = 0.5°N) in the Indian longitude sector. The results indicate a clear seasonal and solar cycle variation in all the three parameters. Further, the seasonal variation of equatorial Spread F (ESF) during the above period is examined in terms of the relative roles of L, the vertical drift and layer height (of the F layer) in the triggering of the collisional Rayleigh-Taylor instability. The results, show for the first time, that L also plays an important role, in controlling the quiet time seasonal and solar cycle variability of ESF; whereas in earlier studies this parameter had been taken to be constant. The detailed results are presented and discussed.

  17. OBSERVATION OF HIGH-SPEED OUTFLOW ON PLUME-LIKE STRUCTURES OF THE QUIET SUN AND CORONAL HOLES WITH SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Tian Hui; McIntosh, Scott W.; Habbal, Shadia Rifal; He Jiansen E-mail: mscott@ucar.edu E-mail: jshept@gmail.com

    2011-08-01

    Observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory reveal ubiquitous episodic outflows (jets) with an average speed around 120 km s{sup -1} at temperatures often exceeding a million degree in plume-like structures, rooted in magnetized regions of the quiet solar atmosphere. These outflows are not restricted to the well-known plumes visible in polar coronal holes, but are also present in plume-like structures originating from equatorial coronal holes and quiet-Sun (QS) regions. Outflows are also visible in the 'inter-plume' regions throughout the atmosphere. Furthermore, the structures traced out by these flows in both plume and inter-plume regions continually exhibit transverse (Alfvenic) motion. Our finding suggests that high-speed outflows originate mainly from the magnetic network of the QS and coronal holes (CHs), and that the plume flows observed are highlighted by the denser plasma contained therein. These outflows might be an efficient means to provide heated mass into the corona and serve as an important source of mass supply to the solar wind. We demonstrate that the QS plume flows can sometimes significantly contaminate the spectroscopic observations of the adjacent CHs-greatly affecting the Doppler shifts observed, thus potentially impacting significant investigations of such regions.

  18. Differential energy spectra of low energy (less than 8.5 MeV per nucleon) heavy cosmic rays during solar quiet times. [from Explorer 47 satellite observation

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Vollmer, O.; Gloeckler, G.; Fan, C. Y.

    1973-01-01

    Explorer 47 satellite observations of carbon, oxygen, and heavier nuclei differential energy spectra below 8.5 MeV/nucleon are presented for solar quiet time periods. A dE/dx vs E method for particle identification and energy determination was used. The instrumentation telescope included an isobutane proportional counter, a surface barrier Si detector, and a cylindrical plastic scintillator anticoincidence shield. The observations were performed outside the bow-shock and in the ecliptic plane. Results show an anisotropy of about 25% at 22 degrees west of the sun with a C/O ratio of 0.5 supporting a solar origin. The low energy portions of the C and O spectra have steep negative slopes, and the corresponding power law is given. Peculiarities in the O spectrum are discussed.

  19. Dependences of statistical characteristics of NmE on the month of the year at middle and low latitudes under daytime geomagnetically quiet conditions at low solar activity

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2016-07-01

    Month-to-month changes in the statistical characteristics of the ionospheric E layer peak electron density NmE at medium and low geomagnetic latitudes under daytime geomagnetically quiet conditions are investigated. Critical frequencies of the ionospheric E layer measured by the middle latitude ionosonde Boulder and low latitude ionosondes Huancayo and Jicamarca at low solar activity from 1957 to 2015 have been used in the conducted statistical analysis. The mathematical expectation of NmE, standard deviation of NmE from the expectation of NmE, and NmE variation coefficient have been calculated for each month of the year. The months of the formation of extrema of these statistical parameters of NmE were found.

  20. Long-term monthly statistics of mid-latitudinal NmF2 in the northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2016-05-01

    Long-term mid-latitude hourly values of NmF2 measured in 1957-2015 by 10 ionosondes in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of the noon NmF2 for each month, including the mathematical expectation, most probable value, arithmetic average, and arithmetic average median. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). The calculated month-to-month variations of the NmF2 statistical parameters made it possible to study the winter anomaly and spring-autumn asymmetry in these statistical parameters.

  1. Heating of the quiet solar corona from measurements of the FET/TESIS instrument on-board the KORONAS-FOTON satellite

    NASA Astrophysics Data System (ADS)

    Rybák, J.; Gömöry, P.; Benz, A.; Bogachev, P.; Brajša, R.

    2010-12-01

    The paper presents the first results of the observations of time evolution of the quiet solar corona brightenings obtained due to very rapid photography of the corona with full-disk EUV telescopes of the FET/TESIS instrument onboard the KORONA FOTON satellite. The measurements were performed simultaneously in the emission of the Fe IX / X 17.1 and Fe VIII 13.1 spectral lines with 10 second temporal cadence and spatial scale of 1.7 arc seconds within one hour. This test observation, carried out on 15 July 2009, was analyzed in order to determine whether this type of observation can be used to identify individual microevents in the solar corona heating that are above the tresholds of spatial and temporal resolutions of the observations of non-active regions in the solar atmosphere. For this purpose, a simple method was used involving cross-correlation of the plasma emission time evolution at different temperatures, each time from observations of identical elements. The results obtained are confronted with the expected observable manifestations of the corona heating via nanoflares. TESIS is a set of instruments for the Sun photography developed in the Lebedev Physics Institute of the Russian Academy of Sciences that was launched into orbit in January 2009.

  2. Fourier transform spectrometer observations of solar carbon monoxide. II - Simultaneous cospatial measurements of the fundamental and first-overtone bands, and Ca II K, in quiet and active regions

    NASA Technical Reports Server (NTRS)

    Ayres, T. R.; Testerman, L.; Brault, J. W.

    1986-01-01

    Fourier transform spectrometry has yielded simultaneous cospatial measurements of important diagnostics of thermal structure in the high solar photosphere and low chromosphere. It is noted that the anomalous behavior of the fundamental bands of CO in quiet areas near the limb is accentuated in an active region plage observed close to the limb. The difference between the core temperatures of the CO fundamental bands in a plage and a nearby quiet region at the limb is larger than the corresponding brightness temperature differences in the inner wings of the Ca II line measured in a quiet region and several plages closer to the disk center. Numerical simulations indicate that the disparate behavior of the CO bands with respect to Ca II K cannot be reconciled with existing single component thermal structure models; a two-component atmosphere is required.

  3. OBSERVATIONS AND MODELING OF THE EMERGING EXTREME-ULTRAVIOLET LOOPS IN THE QUIET SUN AS SEEN WITH THE SOLAR DYNAMICS OBSERVATORY

    SciTech Connect

    Chitta, L. P.; Van Ballegooijen, A. A.; DeLuca, E. E.; Kariyappa, R.; Hasan, S. S.; Hanslmeier, A.

    2013-05-01

    We used data from the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) to study coronal loops at small scales, emerging in the quiet Sun. With HMI line-of-sight magnetograms, we derive the integrated and unsigned photospheric magnetic flux at the loop footpoints in the photosphere. These loops are bright in the EUV channels of AIA. Using the six AIA EUV filters, we construct the differential emission measure (DEM) in the temperature range 5.7-6.5 in log T (K) for several hours of observations. The observed DEMs have a peak distribution around log T Almost-Equal-To 6.3, falling rapidly at higher temperatures. For log T < 6.3, DEMs are comparable to their peak values within an order of magnitude. The emission-weighted temperature is calculated, and its time variations are compared with those of magnetic flux. We present two possibilities for explaining the observed DEMs and temperatures variations. (1) Assuming that the observed loops are composed of a hundred thin strands with certain radius and length, we tested three time-dependent heating models and compared the resulting DEMs and temperatures with the observed quantities. This modeling used enthalpy-based thermal evolution of loops (EBTEL), a zero-dimensional (0D) hydrodynamic code. The comparisons suggest that a medium-frequency heating model with a population of different heating amplitudes can roughly reproduce the observations. (2) We also consider a loop model with steady heating and non-uniform cross-section of the loop along its length, and find that this model can also reproduce the observed DEMs, provided the loop expansion factor {gamma} {approx} 5-10. More observational constraints are required to better understand the nature of coronal heating in the short emerging loops on the quiet Sun.

  4. On the statistical characteristics of radio-loud and radio-quiet halo coronal mass ejections and their associated flares during solar cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Mittal, Nishant; Sharma, Joginder; Verma, Virendar Kumar; Garg, Vijay

    2016-08-01

    We have studied the characteristics of radio-loud (RL) and radio-quiet (RQ) front side halo coronal mass ejections (HCMEs) (angular width 360°) observed between the time period years 1996-2014. RL-HCMEs are associated with type II radio bursts, while RQ-HCMEs are not associated with type II radio bursts. CMEs near the Sun in the interplanetary medium associated with radio bursts also affect the magnetosphere. The type II radio burst data was observed by WIND/WAVES instrument and HCMEs were observed by LASCO/ SOHO instruments. In our study, we have examined the properties of RL-HCMEs and RQ-HCMEs and found that RL-HCMEs follow the solar cycle variation. Our study also shows that the 26% of slow speed HCMEs and 82% of fast speed HCMEs are RL. The average speed of RL-HCMEs and RQ-HCMEs are 1370 km/s and 727 km/s, respectively. Most of the RQ-HCMEs occur around the solar disc center while most of RL-HCMEs are uniformly distributed across the solar disc. The mean value of acceleration of RL-HCMEs is more than twice that of RQ-HCMEs and mean value of deceleration of RL- HCMEs is very small compare to RQ-HCMEs events. It is also found that RQ-HCMEs events are associated with C- and M-class of SXR flares, while RL-HCMEs events are associated with M and X-class of SXR flares, which indicates that the RQ-HCMEs are less energetic than the RL-HCMEs. We have also discussed the various results obtained in present investigation in view of recent scenario of solar physics.

  5. Climatologies of nighttime upper thermospheric winds measured by ground-based Fabry-Perot interferometers during geomagnetically quiet conditions: 1. Local time, latitudinal, seasonal, and solar cycle dependence

    NASA Astrophysics Data System (ADS)

    Emmert, J. T.; Faivre, M. L.; Hernandez, G.; Jarvis, M. J.; Meriwether, J. W.; Niciejewski, R. J.; Sipler, D. P.; Tepley, C. A.

    2006-12-01

    We analyze ground-based Fabry-Perot interferometer observations of upper thermospheric (˜250 km) horizontal neutral winds derived from Doppler shifts in the 630.0 nm (red line) nightglow. The winds were measured over the following locations: South Pole (90°S), Halley (76°S, 27°W), Arequipa (17°S, 72°W), Arecibo (18°N, 67°W), Millstone Hill (43°N, 72°W), Søndre Strømfjord (67°N, 51°W), and Thule (77°N, 68°W). We derive climatological quiet time (Kp < 3) wind patterns as a function of local time, solar cycle, day of year, and the interplanetary magnetic field (IMF), and provide parameterized representations of these patterns. At the high-latitude stations, and at Arequipa near the geomagnetic equator, wind speeds tend to increase with increasing solar extreme ultraviolet (EUV) irradiance. Over Millstone Hill and Arecibo, solar EUV has a negative effect on wind magnitudes. As represented by the 10.7 cm radio flux proxy, the solar EUV dependence of the winds at all latitudes is characterized by a saturation or weakening of the effect above moderate values (F10.7 > 150). The seasonal dependence of the winds is generally annual, but there are isolated cases in which a semiannual variation is observed. Within the austral winter, winds measured from the South Pole show a substantial intraseasonal variation only along longitudes directed toward the magnetic pole. IMF effects are described in a companion paper.

  6. Detection of interplanetary electrons from 18 keV to 1.8 MeV during solar quiet times, 1. On the origin of 200 KeV interplanetary electrons, 2.

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Cline, T. L.; Ramaty, R.; Fisk, L. A.

    1972-01-01

    A quiet time component of interplanetary electrons having energies above solar wind energies and below those characterized as cosmic radiation was observed. Its energy spectrum falls with energy from 18 keV to 1.8 MeV, but it shows a feature in the 100 to 300 keV range. The observed temporal variations of the intensity suggest that the 18 to 100 keV portion is solar and the 0.3 to 1.8 MeV portion is galactic in origin. Solar and terrestrial neutron decay electrons appear inadequate to explain the 100 to 300 keV feature.

  7. Results from the Big Bear Solar Observatory's New Digital Vector Magnetograph

    NASA Astrophysics Data System (ADS)

    Spirock, T. J.; Denker, C.; Varsik, J.; Shumko, S.; Qiu, J.; Gallagher, P.; Chae, J.; Goode, P.; Wang, H.

    2001-05-01

    During the past several years the Big Bear Solar Observatory has been involved in an aggressive program to modernize the observatory's instrumentation. At the forefront of this effort has been the upgrade of the observatory's digital vector magnetograph (DVMG), which has been recently integrated into the observatory's daily observing program. The DVMG, which is mounted on the observatory's 25 cm vacuum refractor, is a highly sensitive, high cadence magnetograph which studies the FeI line at 630.1 nm. An easy to use GUI observing tool has been written to aid instrument development and data acquisition. This tool automatically calibrates the data and generates near real-time vector magnetograms which will aid space weather forecasting and the support of space weather missions. Also, our plan is to integrate the DVMG data into the HESSI Synoptic Archive. The very sensitive quiet Sun magnetograms, produced by the DVMG, will aid the study of small scale magnetic reconnection at the intranetwork level and its possible contribution to the coronal heating problem. Quiet sun longitudinal and active region vector magnetograms will be presented. Image quality, such as bias, cross-talk, noise levels and sensitivity, will be discussed in addition to the improvements gained in post processing such as image selection and image alignment.

  8. Fourier Transform Spectrometer observations of solar carbon monoxide. I - The fundamental and first overtone bands in the quiet sun

    NASA Technical Reports Server (NTRS)

    Ayres, T. R.; Testerman, L.

    1981-01-01

    Measurements of the 2200/cm fundamental and 4300/cm first overtone vibration-rotation band systems of solar carbon monoxide, were obtained with the Fourier Transform Spectrometer of the McMath telescope at Kitt Peak. The overtone measurements were taken at the east, north, and west heliocentric limbs, and at disk center. Observations of the strong fundamental bands were obtained at disk center and near the north limb. The low core brightness temperatures of the strongest fundamental carbon monoxide lines near the limb, reported previously by Noyes (1972) and Hall (1974), are confirmed. The possibility that thermal inhomogeneities might be responsible for the unusual behavior of the fundamental carbon dioxide lines have been examined. The somewhat discordant behavior of the fundamental lines at disk center compared with the north limb seems to favor a limb shadowing effect. The first overtone limb equivalent widths and the best-fit thermal and microvelocity models indicate a solar carbon abundance of 0.004 (on the scale with A sub H = 1) for an oxygen-to-carbon abundance ratio of 2.

  9. On the inability of magnetically constricted transition regions to account for the 10 to the 5th to 10 to the 6th K plasma in the quiet solar atmosphere

    NASA Technical Reports Server (NTRS)

    Dowdy, James F., Jr.; Moore, Ronald L.; Emslie, A. Gordon

    1987-01-01

    Static models of the plasma in the quiet solar atmosphere incorporating not only conduction and radiation but also the effects of large magnetic constrictions are examined. It is found that the bulk of the solar plasma at temperatures below 7 x 10 to the 5th K cannot be produced by a conductive transition region when it is modeled by flux tubes with constriction compatible with observations. The present findings suggest that the major portion of the UEV plasma may be maintained in an ensemble of small, individual magnetic loops located within the supergranular network and having peak temperatures ranging from chromospheric to coronal values.

  10. An introduction to quiet daily geomagnetic fields

    USGS Publications Warehouse

    Campbell, W.H.

    1989-01-01

    On days that are quiet with respect to solar-terrestrial activity phenomena, the geomagnetic field has variations, tens of gamma in size, with major spectral components at about 24, 12, 8, and 6 hr in period. These quiet daily field variations are primarily due to the dynamo currents flowing in the E region of the earth's ionosphere, are driven by the global thermotidal wind systems, and are dependent upon the local tensor conductivity and main geomagnetic field vector. The highlights of the behavior and interpretation of these quiet field changes, from their discovery in 1634 until the present, are discussed as an introduction to the special journal issue on Quiet Daily Geomagnetic Fields. ?? 1989 Birkha??user Verlag.

  11. Statistical Study of Network Jets Observed in the Solar Transition Region: a Comparison Between Coronal Holes and Quiet-Sun Regions

    NASA Astrophysics Data System (ADS)

    Narang, Nancy; Arbacher, Rebecca T.; Tian, Hui; Banerjee, Dipankar; Cranmer, Steven R.; DeLuca, Ed E.; McKillop, Sean

    2016-04-01

    Recent IRIS observations have revealed a prevalence of intermittent small-scale jets with apparent speeds of 80 - 250 km s^{-1}, emanating from small-scale bright regions inside network boundaries of coronal holes. We find that these network jets appear not only in coronal holes but also in quiet-sun regions. Using IRIS 1330 Å (C II) slit-jaw images, we extracted several parameters of these network jets, e.g. apparent speed, length, lifetime, and increase in foot-point brightness. Using several observations, we find that some properties of the jets are very similar, but others are obviously different between the quiet Sun and coronal holes. For example, our study shows that the coronal-hole jets appear to be faster and longer than those in the quiet Sun. This can be directly attributed to a difference in the magnetic configuration of the two regions, with open magnetic field lines rooted in coronal holes and magnetic loops often present in the quiet Sun. We also detected compact bright loops that are most likely transition region loops and are mostly located in quiet-Sun regions. These small loop-like regions are generally devoid of network jets. In spite of different magnetic structures in the coronal hole and quiet Sun in the transition region, there appears to be no substantial difference for the increase in footpoint brightness of the jets, which suggests that the generation mechanism of these network jets is very likely the same in both regions.

  12. Recent Advances in the Exploration of the Small-Scale Structure of the Quiet Solar Atmosphere: Vortex Flows, the Horizontal Magnetic Field, and the Stokes- V Line-Ratio Method

    NASA Astrophysics Data System (ADS)

    Steiner, O.; Rezaei, R.

    2012-05-01

    We review (i) observations and numerical simulations of vortical flows in the solar atmosphere and (ii) measurements of the horizontal magnetic field in quiet Sun regions. First, we discuss various manifestations of vortical flows and emphasize the role of magnetic fields in mediating swirling motion created near the solar surface to the higher layers of the photosphere and to the chromosphere. We reexamine existing simulation runs of solar surface magnetoconvection with regard to vortical flows and compare to previously obtained results. Second, we reviews contradictory results and problems associated with measuring the angular distribution of the magnetic field in quiet Sun regions. Furthermore, we review the Stokes-V-amplitude ratio method for the lines Fe i λλ 630.15 and 630.25 nm. We come to the conclusion that the recently discovered two distinct populations in scatter plots of this ratio must not bee interpreted in terms of “uncollapsed'' and “collapsed'' fields but stem from weak granular magnetic fields and weak canopy fields located at the boundaries between granules and the intergranular space. Based on new simulation runs, we reaffirm earlier findings of a predominance of the horizontal field components over the vertical one, particularly in the upper photosphere and at the base of the chromosphere.

  13. The quiet and disturbed time performance of the IRI 2012 within 90°-130°E longitude sector during solar cycle 24

    NASA Astrophysics Data System (ADS)

    Bhuyan, Pradip; Yokoyama, Tatsuhiro; Supnithi, Pornchai; Kalita, Bitap Raj; Wang, Kehe; Komolmis, Tharadol; Yatini, Clara

    2016-07-01

    The performance of the IRI 2012 model is examined for the double peaked solar cycle 24 in the low latitude region of 90-130oE longitude in the context of the global longitudinal wave number four structure (WN4). The monthly mean values of the foF2 and the hmF2(if available) measurements at low and low mid-latitude stations Dibrugarh (27.5°N, 95°E), Hainan (19.2°N,109.7°E),Okinawa (26.5°N,128°E) and Cocos Island (12.2°S,96.8°E) during quiet times and Dibrugarh (27.5°N, 95°E), Chiang Mai (18.76°N,98.93°E), Chumphon (10.72°N,99.37°E), Kototabang (0.2°S,100.32°E) and Cocos Island (12.2°S,96.8°E ) during the disturbed days of a severe geomagnetic storm are investigated. These stations are located under the strongest peak of the longitudinal WN4 structure in NmF2 along 90-130°E longitudes. The IRI is quite successful in predicting the seasonal averages of NmF2 over this region except in the equinox afternoon period where IRI underestimates the NmF2 in low latitudes. When the monthly mean measured data is compared with IRI, the difference between the IRI model predictions and the measurements are found to follow a systematic pattern. The IRI-2012 with CCIR options slightly underestimates foF2 over Dibrugarh in day time and overestimates in the night time. The amount of underestimation varies from month to month and also depends on the solar activity levels. The IRI also underestimated the day time hmF2 and overestimated the night time hmF2 over Dibrugarh. In case of Hainan, the IRI overestimates the NmF2 in the equinox months and generally in the afternoon to post sunset period. The model values are closer in the solstice than in the equinox. In Okinawa, the trend reverses and the IRI overestimates the NmF2 in the day time and underestimates in the night time. The IRI overestimated the day time hmF2 and underestimated the night time hmF2 over Okinawa. In case of Cocos Island which lies almost on the EIA anomaly region of the southern hemisphere, IRI

  14. Quiet areas and the need for quietness in Amsterdam.

    PubMed

    Booi, Hester; van den Berg, Frits

    2012-04-01

    This paper describes the Quiet Places Project in Amsterdam. The purpose of the study was to find out: (1) which public quiet places there are according to Amsterdam residents; (2) what characterizes a quiet place; (3) to what extent do residents want peace and quiet; (4) how do residents realize these needs. The factors determining the need for quietness are presented in a model showing the influence of demographic and socio-economic issues, health status, sensitiveness to noise, daily activities and the noisiness in and around home. Most important of these factors is sensitivity to noise. Elderly and less healthy people are more often sensitive to noise. People who are annoyed by sound from traffic, airplanes and the like show a higher need for quietness. People with a lively household or neighbourhood report lower needs for quietness. Visiting a quiet place and going outside to walk or bike can have a compensating effect on the need for quietness. This suggests that creating quiet places and enhancing possibilities for quiet recreation in urban environments can have a positive effect on the quality of life in the city. Objective noise levels at the quiet places were taken from environmental noise maps. This shows that there may be a preference for low transportation noise levels, but levels up to 60 dB L(day) are acceptable. Apparently this depends on a relative quietness or on non-acoustic characteristics of an area: the presence of vegetation and other pleasant stimuli. PMID:22690181

  15. Quiet Areas and the Need for Quietness in Amsterdam

    PubMed Central

    Booi, Hester; van den Berg, Frits

    2012-01-01

    This paper describes the Quiet Places Project in Amsterdam. The purpose of the study was to find out: (1) which public quiet places there are according to Amsterdam residents; (2) what characterizes a quiet place; (3) to what extent do residents want peace and quiet; (4) how do residents realize these needs. The factors determining the need for quietness are presented in a model showing the influence of demographic and socio-economic issues, health status, sensitiveness to noise, daily activities and the noisiness in and around home. Most important of these factors is sensitivity to noise. Elderly and less healthy people are more often sensitive to noise. People who are annoyed by sound from traffic, airplanes and the like show a higher need for quietness. People with a lively household or neighbourhood report lower needs for quietness. Visiting a quiet place and going outside to walk or bike can have a compensating effect on the need for quietness. This suggests that creating quiet places and enhancing possibilities for quiet recreation in urban environments can have a positive effect on the quality of life in the city. Objective noise levels at the quiet places were taken from environmental noise maps. This shows that there may be a preference for low transportation noise levels, but levels up to 60 dB Lday are acceptable. Apparently this depends on a relative quietness or on non-acoustic characteristics of an area: the presence of vegetation and other pleasant stimuli. PMID:22690181

  16. Rapid and Quiet Drill

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Chang, Zensheu; Bao, Xiaoqi

    2007-01-01

    This describes aspects of the rapid and quiet drill (RAQD), which is a prototype apparatus for drilling concrete or bricks. The design and basic principle of operation of the RAQD overlap, in several respects, with those of ultrasonic/ sonic drilling and coring apparatuses described in a number of previous NASA Tech Briefs articles. The main difference is that whereas the actuation scheme of the prior apparatuses is partly ultrasonic and partly sonic, the actuation scheme of the RAQD is purely ultrasonic. Hence, even though the RAQD generates considerable sound, it is characterized as quiet because most or all of the sound is above the frequency range of human hearing.

  17. An empirical model of the quiet daily geomagnetic field variation

    USGS Publications Warehouse

    Yamazaki, Y.; Yumoto, K.; Cardinal, M.G.; Fraser, B.J.; Hattori, P.; Kakinami, Y.; Liu, J.Y.; Lynn, K.J.W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V.M.; Otadoy, R.E.; Ruhimat, M.; Shevtsov, B.M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

    2011-01-01

    An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ??? 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity. Copyright 2011 by the American Geophysical Union.

  18. An empirical model of the quiet daily geomagnetic field variation

    NASA Astrophysics Data System (ADS)

    Yamazaki, Y.; Yumoto, K.; Cardinal, M. G.; Fraser, B. J.; Hattori, P.; Kakinami, Y.; Liu, J. Y.; Lynn, K. J. W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V. M.; Otadoy, R. E.; Ruhimat, M.; Shevtsov, B. M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

    2011-10-01

    An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ≤ 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity.

  19. Nanoflare Heating of the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Viall, N. M.; Klimchuk, J. A.

    2015-12-01

    How the solar corona is heated to temperatures of over 1 MK, while the photosphere below is only ~ 6000 K remains one of the outstanding problems in all of space science. Solving this problem is crucial for understanding Sun-Earth connections, and will provide new insight into universal processes such as magnetic reconnection and wave-particle interactions. We use a systematic technique to analyze the properties of coronal heating throughout the solar corona using data taken with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our technique computes cooling times of the coronal plasma on a pixel-by-pixel basis and has the advantage that it analyzes all of the coronal emission, including the diffuse emission surrounding distinguishable coronal features. We have already applied this technique to 15 different active regions, and find clear evidence for dynamic heating and cooling cycles that are consistent with the 'impulsive nanoflare' scenario. What about the rest of the Solar corona? Whether the quiet Sun is heated in a similar or distinct manner from active regions is a matter of great debate. Here we apply our coronal heating analysis technique to quiet Sun locations. We find areas of quiet Sun locations that also undergo dynamic heating and cooling cycles, consistent with impulsive nanoflares. However, there are important characteristics that are distinct from those of active regions.

  20. Characteristics of long-term variation in the amlitude of the geomagnetic solar quiet (Sq) daily variation using the Inter-university Upper atmosphere Gobal Observation NETwork (IUGONET) data analysis system

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.; Otsuka, Y.; Yatagai, A. I.

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet geomagnetic field daily variation (Sq) have been investigated using 1-hour geomagnetic field data obtained from 69 geomagnetic stations in a period of 1947-2013. In the present data analysis, we took advantage of the IUGONET data analysis system. The Sq amplitude clearly showed a 10-12 year solar activity dependence and it tended to enhance during each solar maximum. During the minimum of solar cycle 23/24 in 2008-2009, the Sq amplitude became the smallest in the investigated period. The relationship between the solar F10.7 index and Sq amplitude is approximately linear but 64 percent of geomagnetic stations show a weak nonlinear dependence on the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second order fitting curve between the solar F10.7 index and Sq amplitude during 1947-2013, and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, a majority of the trends in the residual Sq amplitude that passed through a trend test showed a negative value in a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity and residual Sq amplitude showed an anti-correlation for about 71 percent of geomagnetic stations. On the other hand, the residual Sq amplitude in the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies the movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

  1. The Quiet Skies Project

    ERIC Educational Resources Information Center

    Rapp, Steve

    2008-01-01

    To help promote student awareness of the connection between radio astronomy and radio frequency interference (RFI), an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project--the result of a collaboration between the National Aeronautics and Space…

  2. Magnetic Bright Points in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Sánchez Almeida, J.; Bonet, J. A.; Viticchié, B.; Del Moro, D.

    2010-05-01

    We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic concentrations. The measurement is based on a 0farcs1 angular resolution G-band movie obtained with the Swedish Solar Telescope at the solar disk center. We find 0.97 BPs Mm-2, which is a factor 3 larger than any previous estimate. It corresponds to 1.2 BPs per solar granule. Depending on the details of the segmentation, the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their field strength to be 1.5 kG, the detected BPs contribute to the solar magnetic flux with an unsigned flux density between 13 G and 33 G. If network and inter-network regions are counted separately, they contain 2.2 BPs Mm-2 and 0.85 BPs Mm-2, respectively.

  3. The vertical propagation of waves in the solar atmosphere. II Phase delays in the quiet chromosphere and cell-network distinctions

    NASA Technical Reports Server (NTRS)

    Lites, B. W.; Chipman, E. G.; White, O. R.

    1982-01-01

    The differences in the phase of the velocity oscillations between a pair of chromospheric Ca II lines was measured using the Vacuum Tower Telescope at the Sacramento Peak Observatory. The observed phase differences indicate that the acoustic modes are trapped or envanescent, rather than propagating, in the chromosphere. Systematic distinctions are found in the phase delays between quiet network and cell interior regions for both intensity and velocity oscillations in photospheric and chromospheric lines. The theory of linear perturbations in an isothermal atmosphere is invoked to interpret these differences. From this analysis it is found that one or more of the following explanations is possible: (1) the radiative damping is more effective in the network than in the cell interior; (2) the network features exclude oscillations of large horizontal wavenumber; or (3) the scale height of the chromosphere is larger in the network than in the cell interior.

  4. Investigation on Radio-Quiet and Radio-Loud Fast CMEs and Their Associated Flares During Solar Cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Suresh, K.; Shanmugaraju, A.

    2015-03-01

    We present the results of a detailed analysis on the differences between radio-loud (RL) and radio-quiet (RQ) fast coronal mass ejections (CMEs) ( V≥900 km s-1) observed during the period 1996 - 2012. The analysis consists of three different steps in which we examined the properties of (i) RL and RQ CMEs, (ii) accelerating (class-A) and decelerating (class-D) CMEs among RL and RQ CMEs, and (iii) associated flares. The last two steps and events from a longer period are the extensions of the earlier work on RL and RQ CMEs that mainly aimed to determine the reason for the radio-quietness of some fast CMEs. During this period, we found that 38 % of fast CMEs are RL and 62 % of fast CMEs are RQ. Moreover, fewer RQ CMEs occur around the disc centre. The average speeds of RL and RQ CMEs are 1358 km s-1 and 1092 km s-1. Around 10 % of the RQ events are halo CMEs, but ≈ 66 % of RL events are halo CMEs. The mean acceleration or deceleration value of RL-CMEs is slightly greater than that of RQ-CMEs. When we divide these events based on their acceleration behaviour into class A and class D, there are no considerable differences between classes A and D of RL-CMEs or between classes A and D of RQ CMEs, except for their initial acceleration values. But there are significant differences among their associated flare properties. According to our study here, the RQ CMEs are less energetic than RL CMEs, and they are not associated with flares as strong as those associated with RL CMEs. This confirms the previous results that RQ CMEs do not often exceed the critical Alfvén speed of 1000 km s-1 in the outer corona that is needed to produce type II radio bursts.

  5. The Cretaceous Quiet Zone: How Quiet?

    NASA Astrophysics Data System (ADS)

    Gallet, Y.; Dyment, J.; Kitazawa, M.; Bouligand, C.; Hoise, E.; Kim, M.; Savary, J.; Royer, J.; Choi-Dyment, Y.; Gotab, B.

    2005-12-01

    Geomagnetic field intensity variations deduced from magnetostratigraphic data are mainly restricted to the past few million years. As a consequence, many important questions, such as the long-term evolution of the geomagnetic field intensity and the temporal distribution of excursions, remain unsolved yet. The possibility to recover these fluctuations over a long time interval from marine magnetic anomalies is therefore of particular interest. Within the period documented by these anomalies, the Cretaceous Normal Superchron (CNS) presents a major interest in geomagnetism as little is known on the characteristics of the geomagnetic field during this event, except that it apparently did not reverse for about 35 Myr. Cruise Magofond 3 of R/V Suroit (July-August 2005) was dedicated to the CNS, with a target area on the Cretaceous Quiet Zone off Western Africa, on the eastern flank of the Mid-Atlantic Ridge. Both sea-surface and deep tow magnetic anomaly profiles have been collected. Magnetic observatory data from M'Bour (Senegal) and Guimar (Canary Islands) have been regularly transmitted to the ship in order to check for any external magnetic field disturbance which may have affected the data. In addition, seismic reflection data were acquired to insure that the observed anomalies are not caused by the basement topography and, eventually, to estimate and correct such an effect. Altogether, these data brings new constraints on the variability of the geomagnetic field during the superchron. As a preliminary result, they show the occurrence of several consistent short-wavelength magnetic anomalies which may be linked either to short reversed polarity intervals or to excursions. In particular, the ISEA reversed polarity subchron at the beginning of the CNS seems to be present in most profiles. Other observed anomalies may also depict subchrons and would therefore challenge the concept of a non-reversing geodynamo during the exceptionally long CNS.

  6. Quiet time enhancements over African latitudes

    NASA Astrophysics Data System (ADS)

    Orford, Nicola; Katamzi, Zama; Buresova, Dalia

    2016-07-01

    F2 layer disturbances not related to geomagnetic activity are known as quiet time enhancements (QTEs). The phenomenon of QTEs has not yet been studied over African latitudes. We therefore explore the occurrence of QTEs over Africa in order to expand our knowledge on the behaviour of the ionosphere over this region. Several GPS stations in the middle to equatorial latitudes, during the solar minimum (2009) and near solar maximum (2013), are used. This data was examined for possible trends in variation with solar cycle, season and latitude as well as time of commencement of enhancements. Over the southern mid-latitude region of Africa we have observed that the QTEs are more likely to commence during the night in both solar minimum and maximum, however a slightly larger portion of daytime commencements during solar minimum than during solar maximum were observed. The total number of enhancements for the solar minimum period appears greater than during solar maximum. A seasonal trend is seen with the maximum number of enhancements occurring in summer during solar minimum and in winter during solar maximum. We explore further whether these trends are mirrored or different at low latitude/equatorial African regions.

  7. Quiet time particle fluxes and active phenomena on the Sun

    NASA Astrophysics Data System (ADS)

    Ishkov, Vitaly; Zeldovich, Mariya; Logachev, Yurii; Kecskemety, Karoly

    Using ACE, SOHO and STEREO data the connection of quiet time particle fluxes with active processes on the Sun is examined in the 23rd SC. Investigation of the intervals selected in the conditions of low solar activity supports our assumption that the active structures on the Sun arising during minimum solar activity are mostly responsible for background particle fluxes. Sources on the Sun of charged particles with energies 0.3-8 MeV/nucleon have been determined during quiet time periods over all solar cycle by comparison with solar wind fluxes. It is shown that at the solar maximum a part of background fluxes with abundances of C and Fe corresponding to mean values in solar corona resulted from equatorial coronal holes. Bipolar structures arising in the hole area (bright X-ray points) were accompanied in most cases by the ejection of solar plasma according to HINOTORI satellite. The speed of a part of such emissions and open magnetic field lines above coronal holes can allow energetic particles to escape into the interplanetary space. During solar minimum abundances of C and Fe in majority of quiet time fluxes corresponded to solar wind values possibly indicating the common origin of energetic particle and solar wind fluxes.

  8. The QUIET Instrument

    NASA Technical Reports Server (NTRS)

    Gaier, T.; Kangaslahti, P.; Lawrence, C. R.; Leitch, E. M.; Wollack, E. J.

    2012-01-01

    The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ( approx 1 deg.) . Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 micro Ks(exp 1/2)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 micro Ks(exp 1/2) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01 (QUIET Collaboration 2012) The two arrays together cover multipoles in the range l approximately equals 25-975 . These are the largest HEMT-ba.sed arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument,

  9. Achieving a quiet rooftop installation

    SciTech Connect

    Harold, R.G.

    1993-12-01

    This article examines the design considerations for quiet roof top installations of air conditioning systems. The topics of the article include the elements of a quiet installation, acoustic design requirements for minimizing noise problems, incorporating system requirements into the overall design of the building, and survival of the system design through bid review and installation.

  10. Diurnal variation of galactic cosmic ray intensity on quiet days

    NASA Technical Reports Server (NTRS)

    Kumar, S.; Datt, S. C.

    1985-01-01

    A detailed study of the diurnal variation on long term basis was performed on geomagnetically quiet days using the experimental data of the cosmic ray intensity from the worldwide neutron monitoring stations. During the period when the polarity of the solar magnetic field in the Northern Hemisphere of the sun is negative the phase and amplitude of the diurnal anisotropy on quiet days was observed to remain almost constant. When the polarity of solar magnetic field in the Northern Hemisphere changes from negative to positive, a shift in the phase of the diurnal anisotropy on quiet days towards earlier hours is observed and the shift is found to be maximum during minimum solar activity periods 1953-54 and 1975-76. When the polarity of solar magnetic field changes from positive to negative in the Northern Hemisphere of the Sun the phase of the diurnal anisotropy on quiet days recovers to its usual direction of corotational anisotropy and is observed to remain almost constant till the polarity of the solar magnetic field does not change.

  11. Closing the pseudogap quietly

    NASA Astrophysics Data System (ADS)

    Storey, J. G.

    2015-09-01

    The physical properties of hole-doped cuprate high-temperature superconductors are heavily influenced by an energy gap known as the pseudogap whose origin remains a mystery second only to that of superconductivity itself. A key question is whether the pseudogap closes at a temperature T* . The absence of a specific heat anomaly, together with persistent entropy losses up to 300 K, have long suggested that the pseudogap does not vanish at T* . However, amid a growing body of evidence from other techniques pointing to the contrary we revisit this question. Here we investigate if, by adding a temperature dependence to the pseudogap energy and quasiparticle lifetime in the resonating-valence-bond spin-liquid model of Yang, Rice and Zhang, we can close the pseudogap quietly in the specific heat.

  12. UV intensity distributions of the quiet Sun observed with Sunrise

    NASA Astrophysics Data System (ADS)

    Hirzberger, Johann; Feller, A.; Riethmueller, T.; Borrero, J. M.; Schüssler, M.; Barthol, P.; Berkefeld, T.; Gandorfer, A.; Knoelker, M.; Martínez Pillet, V.; Schmidt, W.; Solanki, S.; Title, A.

    High resolution solar images in the near UV have been obtained with the Solar UV Filtergraph (SUFI) onboard the Sunrise balloon borne observatory, amongst others in wavelength regions not accessible from the ground. We present intensity distributions of the quiet Sun at different heliocentric angles, from disk center to the solar limb. These results, obtained in spectral windows at 214 nm, 313 nm (OH band), 388 nm (CN band) and 396.7 nm (CaIIH), represent an important validation of numerical models of the solar photosphere and are, thus, fundamental ingredients for our understanding of the thermal processes in the solar surface region.

  13. The quiet sun

    NASA Technical Reports Server (NTRS)

    Gibson, E. G.

    1973-01-01

    An up-to-date textbook of solar physics is presented. The solar structure and processes, and the interior are described along with the photosphere, the chromosphere, and the corona. The strongest Fraunhofer lines, visible coronal lines, and coronal UV, XUV, and X-ray lines are listed.

  14. Long-term monthly statistics of the mid-latitude ionospheric E-layer peak electron density in the Northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

    Long-term hourly values of the ionospheric E-layer peak electron density, NmE, measured during the time period of 1957-2014 by 4 mid-latitude ionosondes (Wallops Island, Boulder, de l'Ebre, and Rome) in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of NmE close to noon for each month in a year, including the mathematical expectation of NmE, the standard deviations of NmE from the mathematically expected NmE, and the NmE variation coefficient. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). We found that the most probable NmE cannot be considered as the best statistical parameter among the most probable NmE and the mathematically expected NmE in statistical studies of month-to-month variations of NmE. Depending on a choice of an ionosonde and a month, the calculated NmE variation coefficient changes from 5 to 12 %.

  15. The QUIET Instrument

    SciTech Connect

    Bischoff, C.; et al.

    2012-07-01

    The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ({approx}1{sup o}). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 {mu}Ks{sup 1/2}) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0:1. The 84-element W-band polarimeter array has a sensitivity of 87 {mu}Ks{sup 1/2} at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0:01. The two arrays together cover multipoles in the range {ell} {approx} 25 -- 975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument.

  16. Quiet powered-lift propulsion

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Latest results of programs exploring new propulsion technology for powered-lift aircraft systems are presented. Topics discussed include results from the 'quiet clean short-haul experimental engine' program and progress reports on the 'quiet short-haul research aircraft' and 'tilt-rotor research aircraft' programs. In addition to these NASA programs, the Air Force AMST YC 14 and YC 15 programs were reviewed.

  17. The dynamic magnetic quiet Sun: physical mechanisms and UV signature

    NASA Astrophysics Data System (ADS)

    Sánchez Almeida, J.

    2009-04-01

    The changes in the Sun occurring at human time-scales can be pinned down to the presence of magnetic fields. These fields determine the structure of the outer solar atmosphere and, therefore, they are responsible for all the energetic part of the solar spectrum, including the UV. Our understanding of the magnetic fields existing at the base of the atmosphere has changed during the last years. The new spectro-polarimeters reveal an ubiquitous magnetic field, present even in the quiet regions. They are widespread and of complex topology, containing far more (unsigned) magnetic flux and magnetic energy that all traditional manifestations of solar activity. These so-called quiet Sun magnetic fields are the subject of the contribution. I summarize their main observational properties, as well as the models put forward to explain them. According to the common wisdom, they may be generated by a turbulent dynamo driven by convective motions. Their true physical role is not understood yet, but it may be consequential both for the Sun (e.g., in determining the structure of the quiet corona), and for other astronomical objects (e.g., if a turbulent dynamo operates in the Sun, the same mechanism provides a very efficient mean of creating surface magnetic fields in all stars with convective envelopes). I discuss the impact of the quiet Sun fields on the transition region and corona, trying to point out the UV signatures of those fields.

  18. MAGNETIC BRIGHT POINTS IN THE QUIET SUN

    SciTech Connect

    Sanchez Almeida, J.; Bonet, J. A.; Viticchie, B.

    2010-05-20

    We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic concentrations. The measurement is based on a 0.''1 angular resolution G-band movie obtained with the Swedish Solar Telescope at the solar disk center. We find 0.97 BPs Mm{sup -2}, which is a factor 3 larger than any previous estimate. It corresponds to 1.2 BPs per solar granule. Depending on the details of the segmentation, the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their field strength to be 1.5 kG, the detected BPs contribute to the solar magnetic flux with an unsigned flux density between 13 G and 33 G. If network and inter-network regions are counted separately, they contain 2.2 BPs Mm{sup -2} and 0.85 BPs Mm{sup -2}, respectively.

  19. NASA Connect: 'Quieting The Skies'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    From NASA Connect: 'Quieting The Skies' In this animation we see how the ear converts pressure waves into something the brain can perceive as 'sound' NASA engineers and scientists are trying to design airplanes to run as quietly as cars. In this program, students will learn the basics: what sound is, what makes sound, how sound affects us and the environment, and how we measure sound. They will also learn some of the techniques being used by NASA to reduce aircraft noise. The lesson and classroom experiment will involve students in the creation, visualization, and measurement of sound.

  20. NASA Connect: 'Quieting The Skies'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    From NASA Connect: 'Quieting The Skies' Brenda Sullivan, a psychoacoustician, explains how she researces peoples responses to noise with the help of binaural recordings made inside aircraft. NASA engineers and scientists are trying to design airplanes to run as quietly as cars. In this program, students will learn the basics: what sound is, what makes sound, how sound affects us and the environment, and how we measure sound. They will also learn some of the techniques being used by NASA to reduce aircraft noise. The lesson and classroom experiment will involve students in the creation, visualization, and measurement of sound.

  1. 76 FR 64353 - Buy Quiet Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... controls on machinery and equipment and to motivate the development and implementation of Buy Quiet... machinery and equipment who believe ``Buy Quiet'' programs can be effectively and efficiently woven...

  2. A triumph of quiet diplomacy

    SciTech Connect

    Keeny, S.M. Jr.

    1994-11-01

    The new US agreement with North Korea is a breakthrough in the international effort to eliminate the most serious threat to the non-proliferation regime. Despite mutual mistrust, the two sides have, by quiet diplomacy, crafted an ingenious agreement that terminates Pyongyang`s current and future nuclear weapons program in return for economic benefits and an opportunity to join the international community.

  3. Looking for Peace and Quiet

    ERIC Educational Resources Information Center

    Palin, Ray

    2014-01-01

    Ray Palin, librarian at Sunapee Middle High School in Sunapee, New Hampshire describes what it takes to make the school library a space for those looking for "peace and quiet." Palin begins this article by noting that much has been written about the advantages associated with the learning commons model of library design, however less has…

  4. Quiet Sun and its Dynamics as Viewed from the Ground and from Space

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.

    2016-04-01

    Over the last years, state-of-the-art ground-based and/or space-based observations using imaging, spectroscopic and spectropolarimetric instruments, at a wide range of wavelengths, reveal that the quiet Sun, just like active regions, is a highly inhomogeneous and dynamic environment that plays an important role in the dynamics of the entire solar atmosphere. This dynamic quiet Sun is manifested through a number of different types of features and phenomena that occur in a large range of spatial and temporal scales and are nowadays believed to be mostly driven by the local magnetic field and its dynamics. Ground-based observations processed with state-of-the-art, post-processing reconstruction techniques, often combined with simultaneous space-based observations from a variety of instruments on different spacecraft, offer a unique opportunity to investigate and understand the physical conditions of the local plasma, the nature, formation mechanisms and evolution of quiet Sun phenomena and possible interrelationships between quiet Sun phenomena occurring at different heights of the quiet Sun solar atmosphere, from the photosphere and chromosphere to the transition region and low corona. We provide a comprehensive review of our latest understanding of quiet Sun and its dynamics as viewed from the ground and from space and discuss the advantages/disadvantages of ground- and space-based observations and future advents in solar observations with new solar instruments.

  5. Modeling the Quiet Time Outflow Solution in the Polar Cap

    NASA Technical Reports Server (NTRS)

    Glocer, Alex

    2011-01-01

    We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum, The PWOM solves the gyrotropic transport equations for O(+), H(+), and He(+) along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. [2011] of electron density, which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites (Kitamura et al. [2011]). The data and model agree reasonably well. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide validation of the PWOM's ability to model the quiet time ((background" solution.

  6. A nanoflare model of quiet Sun EUV emission

    NASA Astrophysics Data System (ADS)

    Pauluhn, A.; Solanki, S. K.

    2007-01-01

    Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the properties of larger brightenings gives unreliable estimates of the power-law exponent α characterising their distribution. Here we take the approach of statistically modelling light curves representative of the quiet Sun as seen in EUV radiation. The basic assumption is that all quiet-Sun EUV emission is due to micro- and nanoflares, whose radiative energies display a power-law distribution. Radiance values in the quiet Sun follow a lognormal distribution. This is irrespective of whether the distribution is made over a spatial scan or over a time series. We show that these distributions can be reproduced by our simple model. By simultaneously fitting the radiance distribution function and the power spectrum obtained from the light curves emitted by transition region and coronal lines the power-law distribution of micro- and nanoflare brightenings is constrained. A good statistical match to the measurements is obtained for a steep power-law distribution of nanoflare energies, with power-law exponent α> 2. This is consistent with the dominant heat input to the corona being provided by nanoflares, i.e., by events with energies around 1023 erg. In order to reproduce the observed SUMER time series approximately 103 to 104 nanoflares are needed per second throughout the atmosphere of the quiet Sun (assuming the nanoflares to cover an average area of 1013 m2).

  7. The Quiet Explosion

    NASA Astrophysics Data System (ADS)

    2008-07-01

    weak and 'soft' [1], very different from a gamma-ray burst and more in line with what is expected from a normal supernova." So, after the supernova was discovered, the team rapidly observed it from the Asiago Observatory in Northern Italy and established that it was a Type Ic supernova. "These are supernovae produced by stars that have lost their hydrogen and helium-rich outermost layers before exploding, and are the only type of supernovae which are associated with (long) gamma-ray bursts," explains Mazzali. "The object thus became even more interesting!" Earlier this year, an independent team of astronomers reported in the journal Nature that SN 2008D is a rather normal supernova. The fact that X-rays were detected was, they said, because for the first time, astronomers were lucky enough to catch the star in the act of exploding. Mazzali and his team think otherwise. "Our observations and modeling show this to be a rather unusual event, to be better understood in terms of an object lying at the boundary between normal supernovae and gamma-ray bursts." The team set up an observational campaign to monitor the evolution of the supernova using both ESO and national telescopes, collecting a large quantity of data. The early behaviour of the supernova indicated that it was a highly energetic event, although not quite as powerful as a gamma-ray burst. After a few days, however, the spectra of the supernova began to change. In particular Helium lines appeared, showing that the progenitor star was not stripped as deeply as supernovae associated with gamma-ray bursts. Over the years, Mazzali and his group have developed theoretical models to analyse the properties of supernovae. When applied to SN2008D, their models indicated that the progenitor star was at birth as massive as 30 times the Sun, but had lost so much mass that at the time of the explosion the star had a mass of only 8-10 solar masses. The likely result of the collapse of such a massive star is a black hole

  8. STATISTICAL ANALYSIS OF THE VERY QUIET SUN MAGNETISM

    SciTech Connect

    Martinez Gonzalez, M. J.; Manso Sainz, R.; Asensio Ramos, A.

    2010-03-10

    The behavior of the observed polarization amplitudes with spatial resolution is a strong constraint on the nature and organization of solar magnetic fields below the resolution limit. We study the polarization of the very quiet Sun at different spatial resolutions using ground- and space-based observations. It is shown that 80% of the observed polarization signals do not change with spatial resolution, suggesting that, observationally, the very quiet Sun magnetism remains the same despite the high spatial resolution of space-based observations. Our analysis also reveals a cascade of spatial scales for the magnetic field within the resolution element. It is manifest that the Zeeman effect is sensitive to the microturbulent field usually associated with Hanle diagnostics. This demonstrates that Zeeman and Hanle studies show complementary perspectives of the same magnetism.

  9. Microbial proteomics: the quiet revolution

    SciTech Connect

    Seraphin, Bertrand; Hettich, Robert {Bob} L

    2012-01-01

    Technological developments in DNA sequencing and their application to study thousands of microbial genomes or even microbial ecosystems still today often make the headlines of general newspapers and scientific journals. These revolutionary changes are hiding another revolution that is unfolding more quietly in the background: the development of microbial proteomics to study genome expression products. It is important to recognize that while DNA sequencing reveals extensive details about the genomic potential of an organism or community, proteomic measurements reveal the functional gene products that are present and operational under specific environmental conditions, and thus perhaps better characterize the critical biomolecules that execute the life processes (enzymes, signaling, structural factors, etc.).

  10. Smart materials for turbomachinery quieting

    NASA Astrophysics Data System (ADS)

    Jonson, Michael L.; Lysak, Peter D.; Willits, Steven M.

    2000-06-01

    As part of the Defense Advanced Research Projects Agency (DARPA) SAMPSON program, a team has been developing and testing the use of smart materials for quieting turbomachinery. The team is composed of representatives form Pennsylvania State University, General Dynamics Electric Boat, GTE BBN Technologies, and the Naval Surface Warfare Center Carderock Division. Four concepts for quieting were proposed and wind tunnel testing, water tunnel testing, as well as computational fluid dynamic analysis were performed to down select two of the concepts for further consideration: protuberance and gap control. The wind tunnel testing was performed to determine the optimum shape of the protuberance. Water tunnel testing was performed at Penn State University/Applied Research Laboratory to establish the performance of the protuberance and gap control elements. Piezoelectric inchworm actuators, developed by PSU/Center for Acoustics and Vibration, were utilized for the evaluation of the two concepts. GTE BBN Technologies developed the control system simulation for the ultimate concept, the General Dynamics Electric Boat was responsible for hydrodynamic and hydroacoustic analysis. Naval Surface Warfare Center/Carderock Division performed hydrodynamic analysis and developed the rotary component design for the water tunnel test fixture. Successful testing in the twelve- inch diameter water tunnel at PSU/ARL demonstrated superior performance with the gap control concept over the protuberance control concept, and efforts are on-going to develop the final large scale demonstration. This paper summarizes the result of these activities.

  11. Abundances and charge states in quiet-time low-energy ion fluxes at 1 AU

    NASA Astrophysics Data System (ADS)

    Kecskemety, Karoly; Zeldovich, Mariya; Klecker, Berndt; Logachev, Yurii

    Abundances of C and Fe ions with energies 0.04-1.28 MeV/nuc in the 23rd solar activity cycle are examined in the quiet-time fluxes using ACE, SOHO and STEREO data. They are com-bined with charge state measurement data from SEPICA (ACE, 0.18-0.43 MeV/nuc). Quiet periods of solar activity were selected using the criteria a) Jp < 2x10-4 protons/(cm2 s sr MeV) for 4-8 MeV protons (from EPHIN/SOHO) and b) the ratio H/He < 10 at these energies. The values of C/O and Fe/O were determined over the solar cycle and the following was found. In about 50% of the time intervals during high activity they both were near the average values observed in the solar corona, whereas at solar minimum in more than 90% of the periods the ratios were around the solar wind values. Most of the quiet time periods around maximum, which have sufficient statistics show high average Fe charge states (>15), consistent with im-pulsive solar event origin. During the SC minima the abundances in almost all cases correspond to solar wind values. The results obtained suggest that the active structures on the Sun arising at low solar activity are mostly responsible for background particle fluxes at these energies. There may be microflares, disappearing of ribbons, soft X-ray bright points etc.

  12. Studies Highlight Classroom Plight of Quiet Students

    ERIC Educational Resources Information Center

    Sparks, Sarah D.

    2012-01-01

    Educators often look for ways to bring quiet children out of their shells, but emerging research suggests schools can improve academic outcomes for introverted students by reducing the pressure to be outgoing and giving all students a little more time to reflect. A 2011 study found teachers from across K-12 rated hypothetical quiet children as…

  13. A Quiet Place for Student Veterans

    ERIC Educational Resources Information Center

    Hollingsworth, Margaret

    2015-01-01

    As electronic gadgets predominate a student's life, there comes a need for silence. A quiet place free of electromagnetic spectrum waves, dirty and stray electricity, and the endless chirps, whistles, beeps, and customized signaling. A quiet place can offer solitude for meditation, inspiration, and spiritual awareness. Student involvement in the…

  14. Reflections on Wilson's "The Quiet Evolution."

    ERIC Educational Resources Information Center

    Greer, W. Dwaine

    1999-01-01

    Explores Brent Wilson's report "The Quiet Evolution: Changing the Face of Arts Education," focusing on Wilson's reformulation of discipline-based art education and the methodology of the evaluation. Examines the findings and refers to "The Quiet Evolution Executive Summary." (CMK)

  15. MAGNETIC LOOPS IN THE QUIET SUN

    SciTech Connect

    Wiegelmann, T.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Borrero, J. M.; Schmidt, W.; Pillet, V. MartInez; Bonet, J. A.; Domingo, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    We investigate the fine structure of magnetic fields in the atmosphere of the quiet Sun. We use photospheric magnetic field measurements from SUNRISE/IMaX with unprecedented spatial resolution to extrapolate the photospheric magnetic field into higher layers of the solar atmosphere with the help of potential and force-free extrapolation techniques. We find that most magnetic loops that reach into the chromosphere or higher have one footpoint in relatively strong magnetic field regions in the photosphere. Ninety-one percent of the magnetic energy in the mid-chromosphere (at a height of 1 Mm) is in field lines, whose stronger footpoint has a strength of more than 300 G, i.e., above the equipartition field strength with convection. The loops reaching into the chromosphere and corona are also found to be asymmetric in the sense that the weaker footpoint has a strength B < 300 G and is located in the internetwork (IN). Such loops are expected to be strongly dynamic and have short lifetimes, as dictated by the properties of the IN fields.

  16. Magnetic Loops in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Wiegelmann, T.; Solanki, S. K.; Borrero, J. M.; Martínez Pillet, V.; del Toro Iniesta, J. C.; Domingo, V.; Bonet, J. A.; Barthol, P.; Gandorfer, A.; Knölker, M.; Schmidt, W.; Title, A. M.

    2010-11-01

    We investigate the fine structure of magnetic fields in the atmosphere of the quiet Sun. We use photospheric magnetic field measurements from SUNRISE/IMaX with unprecedented spatial resolution to extrapolate the photospheric magnetic field into higher layers of the solar atmosphere with the help of potential and force-free extrapolation techniques. We find that most magnetic loops that reach into the chromosphere or higher have one footpoint in relatively strong magnetic field regions in the photosphere. Ninety-one percent of the magnetic energy in the mid-chromosphere (at a height of 1 Mm) is in field lines, whose stronger footpoint has a strength of more than 300 G, i.e., above the equipartition field strength with convection. The loops reaching into the chromosphere and corona are also found to be asymmetric in the sense that the weaker footpoint has a strength B < 300 G and is located in the internetwork (IN). Such loops are expected to be strongly dynamic and have short lifetimes, as dictated by the properties of the IN fields.

  17. First results on quiet and magnetic granulation from SOUP

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Tarbell, T. D.; Acton, L.; Duncan, D.; Ferguson, S. H.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.; Morrill, M.

    1987-01-01

    The flight of Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 allowed the collection of time sequences of diffraction limited (0.5 arc sec) granulation images with excellent pointing (0.003 arc sec) and completely free of the distortion that plagues groundbased images. The p-mode oscillations are clearly seen in the data. Using Fourier transforms in the temporal and spatial domain, it was shown that the p-modes dominate the autocorrelation lifetime in magnetic regions. When these oscillations are removed the autocorrelation lifetime is found to be 500 sec in quiet and 950 sec in magnetic regions. In quiet areas exploding granules are seen to be common. It is speculated that a significant fraction of granule lifetimes are terminated by nearby explosions. Using local correlation tracking techniques it was able to measure horizontal displacements, and thus transverse velocities, in the magnetic field. In quiet sun it is possible to detect both super and mesogranulation. Horizontal velocities are as great as 1000 m/s and the average velocity is 400 m/s. In magnetic regions horizontal velocities are much less, about 100 m/s.

  18. Small-scale eruptive filaments on the quiet sun

    NASA Technical Reports Server (NTRS)

    Hermans, Linda M.; Martin, Sara F.

    1986-01-01

    A study of a little known class of eruptive events on the quiet sun was conducted. All of 61 small-scale eruptive filamentary structures were identified in a systematic survey of 32 days of H alpha time-lapse films of the quiet sun acquired at Big Bear Solar Observatory. When fully developed, these structures have an average length of 15 arc seconds before eruption. They appear to be the small-scale analog of large-scale eruptive filaments observed against the disk. At the observed rate of 1.9 small-scale eruptive features per field of view per average 7.0 hour day, the rate of occurence of these events on the sun were estimated to be greater than 600 per 24 hour day.. The average duration of the eruptive phase was 26 minutes while the average lifetime from formation through eruption was 70 minutes. A majority of the small-scale filamentary sturctures were spatially related to cancelling magnetic features in line-of-sight photospheric magnetograms. Similar to large-scale filaments, the small-scale filamentary structures sometimes divided opposite polarity cancelling fragments but often had one or both ends terminating at a cancellation site. Their high numbers appear to reflect the much greater flux on the quiet sun. From their characteristics, evolution, and relationship to photospheric magnetic flux, it was concluded that the structures described are small-scale eruptive filaments and are a subset of all filaments.

  19. Magnetospheric convection during quiet or moderately disturbed times

    NASA Technical Reports Server (NTRS)

    Caudal, G.; Blanc, M.

    1988-01-01

    The processes which contribute to the large-scale plasma circulation in the earth's environment during quiet times, or during reasonable stable magnetic conditions are reviewed. The various sources of field-aligned current generation in the solar wind and the magnetosphere are presented. The generation of field-aligned currents on open field lines connected to either polar cap and the generation of closed field lines of the inner magnetosphere are examined. Consideration is given to the hypothesis of Caudal (1987) that loss processes of trapped particles are competing with adiabatic motions in the generation of field-aligned currents in the inner magnetosphere.

  20. Charged Particles in Earth's Magnetosphere during Storm and Quiet time

    NASA Astrophysics Data System (ADS)

    Forster, D. R.; Grande, M.; Perry, C. H.; Davies, J. A.

    2009-04-01

    Ionic number density, taken by the Magnetospheric Ion Composition Spectrometer (MICS) instrument on the Combined Release and Radiation Effects Satellite (CRRES), are used to investigate the behaviour of singly charged Oxygen and Helium ions, and also Alpha Particles, while under both quiet and storm-time conditions during a Solar Maximum Period. Number density data are plotted against Invariant Latitude and Local time. The results of this investigation show clearly an enhancement of all species during periods of highly negative DST, and are in agreement with previous work (Grande et al, 1996, 2004).

  1. PERVASIVE LINEAR POLARIZATION SIGNALS IN THE QUIET SUN

    SciTech Connect

    Bellot Rubio, L. R.; Orozco Suarez, D.

    2012-09-20

    This paper investigates the distribution of linear polarization signals in the quiet-Sun internetwork using ultra-deep spectropolarimetric data. We reduce the noise of the observations as much as is feasible by adding single-slit measurements of the Zeeman-sensitive Fe I 630 nm lines taken by the Hinode spectropolarimeter. The integrated Stokes spectra are employed to determine the fraction of the field of view covered by linear polarization signals. We find that up to 69% of the quiet solar surface at disk center shows Stokes Q or U profiles with amplitudes larger than 0.032% (4.5 times the noise level of 7 Multiplication-Sign 10{sup -5} reached by the longer integrations). The mere presence of linear polarization in most of the quiet Sun implies that the weak internetwork fields must be highly inclined, but we quantify this by inverting those pixels with Stokes Q or U signals well above the noise. This allows for a precise determination of the field inclination, field strength, and field azimuth because the information carried by all four Stokes spectra is used simultaneously. The inversion is performed for 53% of the observed field of view at a noise level of 1.3 Multiplication-Sign 10{sup -4} I{sub c}. The derived magnetic distributions are thus representative of more than half of the quiet-Sun internetwork. Our results confirm the conclusions drawn from previous analyses using mainly Stokes I and V: internetwork fields are very inclined, but except in azimuth they do not seem to be isotropically distributed.

  2. Aeroassist flight experiment guidance Quiet Time

    NASA Technical Reports Server (NTRS)

    Striepe, Scott A.; Suit, William T.

    1988-01-01

    The science experiments for the Aeroassist Flight Experiment (AFE) will be greatly enhanced by taking measurements with no Reaction Control System (RCS) contamination just before perigee. Methods of modifying the AFE guidance to accomplish this are discussed. Several methods that could give up to 30 seconds of quiet time were investigated and the results of these guidance modifications shown. A 20 second quiet time is definitely possible and a 30 second quiet time may be possible if the guidance can be inactive past perigee. Some of the most significant being the criterion for determining if the mission is threatened. A limited follow-on test program is outlined.

  3. The Solar Dynamos

    NASA Astrophysics Data System (ADS)

    Cattaneo, F.

    2000-05-01

    Magnetic activity on the Sun presents us with an interesting dichotomy. On large spatial and temporal scales the solar magnetic field displays a remarkable degree of organization. The 11 years cadence of the solar cycle, Hales' polarity law, and the systematic drift of the regions of emergence of active regions towards the equator throughout the solar cycle are all indicative of a powerful organizing process. On small spatial and temporal scales, the Solar magnetic field appears random and chaotic. It is interesting that recent advances in dynamo theory provide us with a unified approach to solar magnetic activity whereby both large and small scales emerge naturally as dynamo processes associated with rotationally constrained and unconstrained scales of motions in the convection zone (or directly below it). According to this view all coherent scales of motions produce magnetic structures of comparable coherence length. Those that are further endowed with lack of reflectional symmetry by virtue of being rotationally constrained are further associated with inverse cascades that can generate magnetic structures on larger scales still. The picture that emerges is one in which dynamo action proceeds on different time scales all over the convection zone. But only in very special regions, like for instance the solar tachocline, is the magnetic field organized on large scales. This idea provides a natural explanation for the origin of active regions, ephemeral regions, and intra--network fields.

  4. Small-scale swirl events in the quiet Sun chromosphere

    NASA Astrophysics Data System (ADS)

    Wedemeyer-Böhm, S.; Rouppe van der Voort, L.

    2009-11-01

    Context: Recent progress in instrumentation enables solar observations with high resolution simultaneously in the spatial, temporal, and spectral domains. Aims: We use such high-resolution observations to study small-scale structures and dynamics in the chromosphere of the quiet Sun. Methods: We analyse time series of spectral scans through the Ca ii 854.2 nm spectral line obtained with the CRISP instrument at the Swedish 1-m Solar Telescope. The targets are quiet Sun regions inside coronal holes close to disc-centre. Results: The line core maps exhibit relatively few fibrils compared to what is normally observed in quiet Sun regions outside coronal holes. The time series show a chaotic and dynamic scene that includes spatially confined “swirl” events. These events feature dark and bright rotating patches, which can consist of arcs, spiral arms, rings or ring fragments. The width of the fragments typically appears to be of the order of only 0.2 arcsec, which is close to the effective spatial resolution. They exhibit Doppler shifts of -2 to -4 km s-1 but sometimes up to -7 km s-1, indicating fast upflows. The diameter of a swirl is usually of the order of 2´´. At the location of these swirls, the line wing and wide-band maps show close groups of photospheric bright points that move with respect to each other. Conclusions: A likely explanation is that the relative motion of the bright points twists the associated magnetic field in the chromosphere above. Plasma or propagating waves may then spiral upwards guided by the magnetic flux structure, thereby producing the observed intensity signature of Doppler-shifted ring fragments. The movie is only available in electronic form at http://www.aanda.org Marie Curie Intra-European Fellow of the European Commission.

  5. NASA's Quiet Aircraft Technology Project

    NASA Technical Reports Server (NTRS)

    Whitfield, Charlotte E.

    2004-01-01

    NASA's Quiet Aircraft Technology Project is developing physics-based understanding, models and concepts to discover and realize technology that will, when implemented, achieve the goals of a reduction of one-half in perceived community noise (relative to 1997) by 2007 and a further one-half in the far term. Noise sources generated by both the engine and the airframe are considered, and the effects of engine/airframe integration are accounted for through the propulsion airframe aeroacoustics element. Assessments of the contribution of individual source noise reductions to the reduction in community noise are developed to guide the work and the development of new tools for evaluation of unconventional aircraft is underway. Life in the real world is taken into account with the development of more accurate airport noise models and flight guidance methodology, and in addition, technology is being developed that will further reduce interior noise at current weight levels or enable the use of lighter-weight structures at current noise levels.

  6. Quiet Supersonic Wind Tunnel Development

    NASA Technical Reports Server (NTRS)

    King, Lyndell S.; Kutler, Paul (Technical Monitor)

    1994-01-01

    The ability to control the extent of laminar flow on swept wings at supersonic speeds may be a critical element in developing the enabling technology for a High Speed Civil Transport (HSCT). Laminar boundary layers are less resistive to forward flight than their turbulent counterparts, thus the farther downstream that transition from laminar to turbulent flow in the wing boundary layer is extended can be of significant economic impact. Due to the complex processes involved experimental studies of boundary layer stability and transition are needed, and these are performed in "quiet" wind tunnels capable of simulating the low-disturbance environment of free flight. At Ames, a wind tunnel has been built to operate at flow conditions which match those of the HSCT laminar flow flight demonstration 'aircraft, the F-16XL, i.e. at a Mach number of 1.6 and a Reynolds number range of 1 to 3 million per foot. This will allow detailed studies of the attachment line and crossflow on the leading edge area of the highly swept wing. Also, use of suction as a means of control of transition due to crossflow and attachment line instabilities can be studied. Topics covered include: test operating conditions required; design requirements to efficiently make use of the existing infrastructure; development of an injector drive system using a small pilot facility; plenum chamber design; use of computational tools for tunnel and model design; and early operational results.

  7. Near field zones of quiet

    NASA Astrophysics Data System (ADS)

    Joseph, P.; Elliott, S. J.; Nelson, P. A.

    1994-05-01

    This paper examines the consequences of driving a single secondary loudspeaker to cancel the pressure due to some primary source at a point in its near field. This simple technique has been applied to the sound field in a highly reverberant room to produce zones of quiet in the vicinity of the loudspeaker, which have diameters that are typically equal to one-tenth of the acoustic wavelength, within which the sound pressure level is attenuated by at least 10 dB. The principal advantage gained with this strategy over other active techniques for controlling the sound field in rooms is that the sound pressure level well away from the control point is largely unaffected, an increase of only a small fraction of one dB being typical. Such a loudspeaker-microphone configuration could be located, for example, in the head rests of cars or aeroplanes, or indeed anywhere where the listener is seated for significant lengths of time and subjected to high ambient noise levels such that auditory comfort may be disturbed.

  8. Quiet High-Speed Fan

    NASA Technical Reports Server (NTRS)

    Lieber, Lysbeth; Repp, Russ; Weir, Donald S.

    1996-01-01

    A calibration of the acoustic and aerodynamic prediction methods was performed and a baseline fan definition was established and evaluated to support the quiet high speed fan program. A computational fluid dynamic analysis of the NASA QF-12 Fan rotor, using the DAWES flow simulation program was performed to demonstrate and verify the causes of the relatively poor aerodynamic performance observed during the fan test. In addition, the rotor flowfield characteristics were qualitatively compared to the acoustic measurements to identify the key acoustic characteristics of the flow. The V072 turbofan source noise prediction code was used to generate noise predictions for the TFE731-60 fan at three operating conditions and compared to experimental data. V072 results were also used in the Acoustic Radiation Code to generate far field noise for the TFE731-60 nacelle at three speed points for the blade passage tone. A full 3-D viscous flow simulation of the current production TFE731-60 fan rotor was performed with the DAWES flow analysis program. The DAWES analysis was used to estimate the onset of multiple pure tone noise, based on predictions of inlet shock position as a function of the rotor tip speed. Finally, the TFE731-60 fan rotor wake structure predicted by the DAWES program was used to define a redesigned stator with the leading edge configured to minimize the acoustic effects of rotor wake / stator interaction, without appreciably degrading performance.

  9. Time evolution of a single, quiet-Sun magnetic structure

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Bonet, José Antonio; Solanki, Sami K.; Bellot Rubio, L. R.; Del Toro Iniesta, Jose Carlos

    Isolated flux tubes are considered to be fundamental magnetic building blocks of the solar photosphere. Their formation is usually attributed to the concentration of magnetic field to kG strengths by the convective instability mechanism. However, the small size of the magnetic elements in quiet-Sun areas has prevented this scenario from being studied in fully resolved structures. Here we report on the formation and subsequent evolution of a photospheric magnetic flux tube, observed in the quiet Sun with unprecedented spatial resolution (0. ('') 15 - 0. ('') 18) and high temporal cadence (33 s). The observations were acquired by the Imaging Magnetograph Experiment (IMaX) aboard the textsc{Sunrise} balloon-borne solar observatory. The equipartition field strength magnetic element is reached from the merging of several magnetic flux patches in a mesogranule-sized sink. The magnetic structure is then further intensified to kG field strengths by convective collapse and granular compression. The fine structure found within the flux concentration reveal that the scenario is more complex than a canonical flux tube model. After a subsequent weakening process, the field is further intensified to kG strengths. Seen as a whole, the evolution of the magnetic structure is compatible with oscillations in all basic physical quantities. A discussion on whether this evolution fits to the current theoretical descriptions is also presented.

  10. ON THE PROBABLE EXISTENCE OF AN ABRUPT MAGNETIZATION IN THE UPPER CHROMOSPHERE OF THE QUIET SUN

    SciTech Connect

    Stepan, JirI; Trujillo Bueno, Javier E-mail: jtb@iac.es

    2010-03-10

    We report on a detailed radiative transfer modeling of the observed scattering polarization in the H{alpha} line, which allows us to infer quantitative information on the magnetization of the quiet solar chromosphere. Our analysis suggests the presence of a magnetic complexity zone with a mean field strength (B) > 30 G lying just below the sudden transition region to the coronal temperatures. The chromospheric plasma directly underneath is very weakly magnetized, with (B) {approx} 1 G. The possible existence of this abrupt change in the degree of magnetization of the upper chromosphere of the quiet Sun might have large significance for our understanding of chromospheric (and, therefore, coronal) heating.

  11. SMALL MAGNETIC LOOPS CONNECTING THE QUIET SURFACE AND THE HOT OUTER ATMOSPHERE OF THE SUN

    SciTech Connect

    Martinez Gonzalez, M. J.; Manso Sainz, R.; Asensio Ramos, A.

    2010-05-01

    Sunspots are the most spectacular manifestation of solar magnetism, yet 99% of the solar surface remains 'quiet' at any time of the solar cycle. The quiet sun is not void of magnetic fields, though; they are organized at smaller spatial scales and evolve relatively fast, which makes them difficult to detect. Thus, although extensive quiet Sun magnetism would be a natural driver to a uniform, steady heating of the outer solar atmosphere, it is not clear what the physical processes involved would be, due to lack of observational evidence. We report on the topology and dynamics of the magnetic field in very quiet regions of the Sun from spectropolarimetric observations of the Hinode satellite, showing a continuous injection of magnetic flux with a well-organized topology of {omega}-loop from below the solar surface into the upper layers. At first stages, when the loop travels across the photosphere, it has a flattened (staple-like) geometry and a mean velocity ascent of {approx}3 km s{sup -1}. When the loop crosses the minimum temperature region, the magnetic fields at the footpoints become almost vertical and the loop topology resembles a potential field. The mean ascent velocity at chromospheric height is {approx}12 km s{sup -1}. The energy input rate of these small-scale loops in the lower boundary of the chromosphere is (at least) of 1.4 x 10{sup 6}-2.2 x 10{sup 7} erg cm{sup -2} s{sup -1}. Our findings provide empirical evidence for solar magnetism as a multi-scale system, in which small-scale low-flux magnetism plays a crucial role, at least as important as active regions, coupling different layers of the solar atmosphere and being an important ingredient for chromospheric and coronal heating models.

  12. Analysis of blinkers and EUV brightenings in the quiet Sun observed with CDS

    NASA Astrophysics Data System (ADS)

    Brković, A.; Solanki, S. K.; Rüedi, I.

    2001-07-01

    Movies of quiet Sun regions at disc centre obtained with the Coronal Diagnostic Spectrometer (CDS) onboard the SOHO spacecraft are used to study the properties of transient brightenings seen in the extreme ultraviolet (EUV), so-called blinkers, at three different temperatures sampled simultaneously in the chromospheric He I 584.3 Å (2 x 104 K), the transition region O V 629.7 Å (2.5 x 105 K) and coronal Mg IX 368.1 Å (106 K) lines. Blinkers, here defined somewhat differently than in previous studies, were clearly detected in the O V and He I lines. Brightenings of the Mg IX line were also seen. A thorough analysis of blinker properties is carried out and their detailed properties are determined. Blinkers are found to be present in both bright (network) and dark (intranetwork) regions, but their number density is larger in the brighter areas (in O V) although the rest of their properties appear to be unaffected. The average sizes of brightenings range from 2.8 Mm2 in Mg IX, 12.4 Mm2 in He I to 23.5 Mm2 in O V. The durations of blinkers are in the range 3-110 min, with the average durations being 23 min in He I, about 16 min in O V and 12 min in Mg IX. The frequency distributions of ratio of peak to background intensity, excess energy and size follow power laws with exponents <-5 for the intensity ratio, and between -1 and -3 for the other two parameters. The correlation coefficients between pairs of ratio, energy and size are at least 0.5, while other pairs of parameters describing the blinkers appear to be uncorrelated. The best correlation is between size and energy. The blinker durations exhibit a distribution whose form is compatible with a log-normal function. Finally, blinkers in the 3 lines (i.e. 3 temperature regimes) are poorly correlated; with the correlation coefficient being always less than 0.4. This suggests that to a large extent the transition region reacts independently of the corona and chromosphere to energy deposition, so that these parts of

  13. A substantial amount of hidden magnetic energy in the quiet Sun.

    PubMed

    Bueno, J Trujillo; Shchukina, N; Ramos, A Asensio

    2004-07-15

    Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal heating. At present, we can see only approximately 1 per cent of the complex magnetism of the quiet Sun, which highlights the need to develop a reliable way to investigate the remaining 99 per cent. Here we report three-dimensional radiative transfer modelling of scattering polarization in atomic and molecular lines that indicates the presence of hidden, mixed-polarity fields on subresolution scales. Combining this modelling with recent observational data, we find a ubiquitous tangled magnetic field with an average strength of approximately 130 G, which is much stronger in the intergranular regions of solar surface convection than in the granular regions. So the average magnetic energy density in the quiet solar photosphere is at least two orders of magnitude greater than that derived from simplistic one-dimensional investigations, and sufficient to balance radiative energy losses from the solar chromosphere. PMID:15254531

  14. EMIC waves observed at geosynchronous orbit under quiet geomagnetic conditions (Kp ≤ 1)

    NASA Astrophysics Data System (ADS)

    Park, J.-S.; Kim, K.-H.; Shiokawa, K.; Lee, D.-H.; Lee, E.; Kwon, H.-J.; Jin, H.; Jee, G.

    2016-02-01

    We statistically study the local time distribution of the helium band electromagnetic ion cyclotron (EMIC) waves observed at geosynchronous orbit when geomagnetic activity was low (Kp ≤ 1). In order to identify the geosynchronous EMIC waves, we use high time resolution magnetic field data acquired from GOES 10, 11, and 12 over a 2 year period from 2007 and 2008 and examine the local time distribution of EMIC wave events. Unlike previous studies, which reported high EMIC wave occurrence in the postnoon sector with a peak around 1500-1600 magnetic local time (MLT) during magnetically disturbed times (i.e., storm and/or substorm), we observed that quiet time EMIC waves mostly occur in a region from morning (˜0600 MLT) to afternoon (˜1600 MLT) with a peak around 1100-1200 MLT. To investigate whether the quiet time EMIC wave occurrence has a causal relationship with magnetospheric convection enhancement or solar wind dynamic pressure variations, we performed a superposed epoch analysis of solar wind parameters (solar wind speed, density, dynamic pressure, and interplanetary magnetic field Bz) and geomagnetic indices (AE and SYM-H). From the superposed epoch analysis we found that solar wind dynamic pressure variation is a more important parameter than AE and SYM-H for quiet time EMIC wave occurrence.

  15. Determination of the radial gradient in the region 0.81-1.0 AU using both high- and low-energy /more than 10-GeV and more than 52-MeV/ detectors for the 1-AU monitor. [solar quiet measurements of alpha particles and protons

    NASA Technical Reports Server (NTRS)

    Sheldon, W. R.; Bukata, R. P.; Rao, U. R.

    1974-01-01

    A determination of the radial gradient for alpha particles (31-46 MeV/nuc) and protons with energies above 7.5 MeV and 44-77 MeV in the region 1.0-0.81 AU is presented for the solar-quiet year 1966. The determinations are based on data from the Pioneer 6 space probe. Two different detectors are used: the Deep River neutron monitor and measurements of low energy protons made on the IMP-C satellite. The average energy response of the Deep River monitor is 16 GeV, whereas the IMP-C data is for protons with energies above 50 MeV. The resulting radial gradient is found to be nearly zero for the alpha particles and slightly negative for the protons. The same qualitative results were found using the IMP-C data and the Deep River neutron monitor to measure the temporal variation in the cosmic ray intensity. The present analysis indicates that detectors over a wide range of energies are suitable for measuring the radial gradient, providing sufficient statistical precision is obtained to evaluate short-term modulation and the azimuthal separation of the detectors is not great.

  16. 47 CFR 1.924 - Quiet zones.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... impact on the operations of radio astronomy or other facilities that are highly sensitive to interference. Consent throughout this paragraph means written consent from the quiet zone, radio astronomy, research... Radio Astronomy Observatory site located at Green Bank, Pocahontas County, West Virginia, and at...

  17. 47 CFR 1.924 - Quiet zones.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... impact on the operations of radio astronomy or other facilities that are highly sensitive to interference. Consent throughout this paragraph means written consent from the quiet zone, radio astronomy, research... Radio Astronomy Observatory site located at Green Bank, Pocahontas County, West Virginia, and at...

  18. MASS COMPOSITION IN PRE-ERUPTION QUIET SUN FILAMENTS

    SciTech Connect

    Kilper, Gary; Gilbert, Holly; Alexander, David

    2009-10-10

    Filament eruptions are extremely important phenomena due to their association with coronal mass ejections and their effects on space weather. Little is known about the filament mass and composition in the eruption process, since most of the related research has concentrated on the evolution and disruption of the magnetic field. Following up on our previous work, we present here an analysis of nineteen quiet Sun filament eruptions observed by Mauna Loa Solar Observatory in Halpha and He I 10830 A that has identified a compositional precursor common to all of these eruptions. There is a combined trend of an apparent increase in the homogenization of the filament mass composition, with concurrent increases in absorption in Halpha and He I and in the level of activity, all starting at least one day prior to eruption. This finding suggests that a prolonged period of mass motions, compositional mixing, and possibly even extensive mass loading is occurring during the build up of these eruptions.

  19. The elemental and isotopic composition of quiet time low energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Smith, B.; Mcdonald, F. B.

    1983-01-01

    Isotopic abundances during several periods of solar quiet times are derived from multidimensional analysis of double dE/dX modes made with two 150 micron dE detectors and a 3000 micron stopping E detector. The spectra of the low-energy cosmic rays suggest that all the primary species of elements exhibit flux enhancements. The flux increases of 5-12 MeV/N for C, Mg, Si, and Fe are different from the anomalous components and may result from solar contamination of the quiet time data or from interplanetary acceleration processes. They may be anomalous components (ACR), although to a lesser extent than He, N, O, and Ne. The isotopic data indicate that the ACR component is predominantly N-14, O-16, and Ne-20. The isotopic compositions require that the ACRs have traversed a very limited amount of material, suggesting a local origin for them.

  20. QUIET-SUN INTENSITY CONTRASTS IN THE NEAR-ULTRAVIOLET AS MEASURED FROM SUNRISE

    SciTech Connect

    Hirzberger, J.; Feller, A.; Riethmueller, T. L.; Schuessler, M.; Borrero, J. M.; Gandorfer, A.; Solanki, S. K.; Barthol, P.; Afram, N.; Unruh, Y. C.; Berdyugina, S. V.; Berkefeld, T.; Schmidt, W.; Bonet, J. A.; MartInez Pillet, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    We present high-resolution images of the Sun in the near-ultraviolet spectral range between 214 nm and 397 nm as obtained from the first science flight of the 1 m SUNRISE balloon-borne solar telescope. The quiet-Sun rms intensity contrasts found in this wavelength range are among the highest values ever obtained for quiet-Sun solar surface structures-up to 32.8% at a wavelength of 214 nm. We compare the rms contrasts obtained from the observational data with theoretical intensity contrasts obtained from numerical magnetohydrodynamic simulations. For 388 nm and 312 nm the observations agree well with the numerical simulations whereas at shorter wavelengths discrepancies between observed and simulated contrasts remain.

  1. Quiet-sun Intensity Contrasts in the Near-ultraviolet as Measured from SUNRISE

    NASA Astrophysics Data System (ADS)

    Hirzberger, J.; Feller, A.; Riethmüller, T. L.; Schüssler, M.; Borrero, J. M.; Afram, N.; Unruh, Y. C.; Berdyugina, S. V.; Gandorfer, A.; Solanki, S. K.; Barthol, P.; Bonet, J. A.; Martínez Pillet, V.; Berkefeld, T.; Knölker, M.; Schmidt, W.; Title, A. M.

    2010-11-01

    We present high-resolution images of the Sun in the near-ultraviolet spectral range between 214 nm and 397 nm as obtained from the first science flight of the 1 m SUNRISE balloon-borne solar telescope. The quiet-Sun rms intensity contrasts found in this wavelength range are among the highest values ever obtained for quiet-Sun solar surface structures—up to 32.8% at a wavelength of 214 nm. We compare the rms contrasts obtained from the observational data with theoretical intensity contrasts obtained from numerical magnetohydrodynamic simulations. For 388 nm and 312 nm the observations agree well with the numerical simulations whereas at shorter wavelengths discrepancies between observed and simulated contrasts remain.

  2. Densities in the quiet sun and coronal holes using EUV emission lines

    NASA Astrophysics Data System (ADS)

    Dwivedi, Bhola N.

    1989-03-01

    The density dependence of solar EUV line intensity ratios from Mg VIII, Si VII, S IX and Si IX ions have been used to determine electron densities in the quiet sun and coronal holes. The line intensity values have been computed using a model atmosphere of Kopp and Orrall (1976) in order to emphasize the utility of the lines studied which could be compared with observational data that future missions might provide.

  3. 3D Radiative MHD Modeling of Quiet-Sun Magnetic Activity

    NASA Astrophysics Data System (ADS)

    Kitiashvili, Irina

    2016-05-01

    Quiet-Sun regions that cover most of the solar surface represent a background state that plays an extremely important role in the dynamics and energetics of the solar atmosphere. A clear understanding of these regions is required for accurate interpretation of solar activity events such as emergence of magnetic flux, sunspot formation, and eruptive dynamics. Modern high-resolution observations from ground and space telescopes have revealed a complicated dynamics of turbulent magnetoconvection and its effects in the solar atmosphere and corona, showing intense interactions across different temporal and spatial scales. Interpretation of the observed complex phenomena and understanding of their origins is impossible without advanced numerical models. I will present new results of realistic-type 3D radiative MHD simulations of the upper turbulent convective layer and atmosphere of the Sun. The results reveal the mechanism of formation and properties of the Sun’s “magnetic carpet” controlled by subsurface small-scale dynamo processes, and demonstrate interaction between the subsurface layers and the atmosphere via spontaneous small-scale eruptions and wave phenomena. To link the simulations to solar data the spectro-polarimetric radiative transfer code SPINOR is used to convert the simulated data into the Stokes profiles of various spectral lines, including the SDO and Hinode observables. The results provide a detailed physical understanding of the quiet-Sun dynamics, and show potential for future observations with the DKIST and other large solar telescopes.

  4. Determining Orientation in Radio-Quiet Quasars

    NASA Astrophysics Data System (ADS)

    Brotherton, Michael S.; Singh, Vikram; Runnoe, Jessie C.

    2016-01-01

    We present further steps developing an orientation indicator based on optical parameters that can be used for radio-quiet quasars. We recently demonstrated that the ratio of orientation-biased black hole mass calculated using the velocity width of Hbeta to the orientation-unbiased black hole mass calculated using the stellar velocity dispersion correlates with radio-loud orientation indicators, albeit with significant scatter. Our new work eliminates or reduces some sources of scatter to improve the significance of the correlation and to produce a better predictive prescription. Beyond biasing some mass measurements, orientation also affects luminosity determinations, and in turn estimates of the Eddington fraction, as well as luminosity functions, and other quasar properties. A practical radio-quiet orientation indicator for quasars is overdue.

  5. Mideast stays quiet but has vigor

    SciTech Connect

    Not Available

    1985-05-01

    New drilling activity in the Middle East comes in the Egyptian Red Sea and at both Yemen and Qatar. The last in the scene of the giant North Dome gas development. Otherwise the Mideast sector is quiet with hard production ceilings demanded by OPEC and a war on the east coast of the gulf causing more confusion. A review of the current activity is presented.

  6. BUY QUIET INITIATIVE IN THE USA

    PubMed Central

    Beamer, Bryan; McCleery, Trudi; Hayden, Charles

    2016-01-01

    Noise-induced hearing loss is still considered one of the most common work-related illnesses in the United States of America. The U.S. National Institute for Occupational Safety and Health launched a national Buy Quiet campaign to raise awareness of the importance of purchasing quieter equipment. Buy Quiet encourages companies to seek out and demand quieter equipment thus driving the market to design and create quieter products. In the long run, investment in noise controls should be more prevalent as the market demands quieter products. This paradigm occurs as the market for quieter products expands both from the supply side (manufacturers) and the demand side (tool and equipment purchasers). The key to experiencing the reduced costs and increased benefits of Buy Quiet will be to develop partnerships between manufacturers and consumers. To this end, the U.S. National Institute for Occupational Safety and Health continues to work with partners to educate stakeholders about the risks and true costs of noise-induced hearing loss, as well as the economic benefits of buying quieter equipment. PMID:27274613

  7. EXCITATION OF ACOUSTIC WAVES BY VORTICES IN THE QUIET SUN

    SciTech Connect

    Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A.

    2011-02-01

    The five-minute oscillations are one of the basic properties of solar convection. Observations show a mixture of a large number of acoustic wave fronts propagating from their sources. We investigate the process of acoustic waves excitation from the point of view of individual events, by using a realistic three-dimensional radiative hydrodynamic simulation of the quiet Sun. The results show that the excitation events are related to the dynamics of vortex tubes (or swirls) in intergranular lanes of solar convection. These whirlpool-like flows are characterized by very strong horizontal velocities (7-11 km s{sup -1}) and downflows ({approx}7 km s{sup -1}), and are accompanied by strong decreases of temperature, density, and pressure at the surface and 0.5-1 Mm below the surface. High-speed whirlpool flows can attract and capture other vortices. According to our simulation results the processes of vortex interaction, such as vortex annihilation, can cause excitation of acoustic waves on the Sun.

  8. Low-latitude Pi2 pulsations during intervals of quiet geomagnetic conditions (Kp≤1)

    NASA Astrophysics Data System (ADS)

    Kwon, H.-J.; Kim, K.-H.; Jun, C.-W.; Takahashi, K.; Lee, D.-H.; Lee, E.; Jin, H.; Seon, J.; Park, Y.-D.; Hwang, J.

    2013-10-01

    It has been reported that Pi2 pulsations can be excited under extremely quiet geomagnetic conditions (Kp=0). However, there have been few comprehensive reports of Pi2 pulsations in such a near ground state magnetosphere. To understand the characteristics of quiet-time Pi2 pulsations, we statistically examined Pi2 events observed on the nightside between 1800 and 0600 local time at the low-latitude Bohyun (BOH, L = 1.35) station in South Korea. We chose year 2008 for analysis because geomagnetic activity was unusually low in that year. A total of 982 Pi2 events were identified when Kp≤1. About 80% of the Pi2 pulsations had a period between 110 and 300 s, which significantly differs from the conventional Pi2 period from 40 to 150 s. Comparing Pi2 periods and solar wind conditions, we found that Pi2 periods decrease with increasing solar wind speed, consistent with the result of Troitskaya (1967). The observed wave properties are discussed in terms of plasmaspheric resonance, which has been proposed for Pi2 pulsations in the inner magnetosphere. We also found that Pi2 pulsations occur quasi-periodically with a repetition period of ˜23-38 min. We will discuss what determines such a recurrence time of Pi2 pulsations under quiet geomagnetic conditions.

  9. Combining quiet- and disturbance-hmF2 models to provide a forecasting tool for hmF2

    NASA Astrophysics Data System (ADS)

    Magdaleno, Sergio; Blanch, Estefanía.; Herraiz, Miguel; Altadill, David; de La Morena, Benito

    2010-05-01

    The quiet behavior of the ionospheric electron density peak height of the F2 region, hmF2, at mid latitude has been evaluated from average electron density profiles providing more reliable hmF2 measurement than converting hmF2 from M(3000)F2. A model temporal extent has been obtained by considering the daily and seasonal variations and the solar activity influence on them. The quiet-hmF2 model provides better performance than current IRI does. A disturbance-hmF2 model has been added to the quiet-hmF2 providing a forecasting tool for hmF2 in response to the configuration and variation of the interplanetary magnetic field. The performance of this tool under particular events will be presented.

  10. Design of Quiet Rotorcraft Approach Trajectories

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Burley, Casey L.; Boyd, D. Douglas, Jr.; Marcolini, Michael A.

    2009-01-01

    A optimization procedure for identifying quiet rotorcraft approach trajectories is proposed and demonstrated. The procedure employs a multi-objective genetic algorithm in order to reduce noise and create approach paths that will be acceptable to pilots and passengers. The concept is demonstrated by application to two different helicopters. The optimized paths are compared with one another and to a standard 6-deg approach path. The two demonstration cases validate the optimization procedure but highlight the need for improved noise prediction techniques and for additional rotorcraft acoustic data sets.

  11. The quiet revolution of numerical weather prediction

    NASA Astrophysics Data System (ADS)

    Bauer, Peter; Thorpe, Alan; Brunet, Gilbert

    2015-09-01

    Advances in numerical weather prediction represent a quiet revolution because they have resulted from a steady accumulation of scientific knowledge and technological advances over many years that, with only a few exceptions, have not been associated with the aura of fundamental physics breakthroughs. Nonetheless, the impact of numerical weather prediction is among the greatest of any area of physical science. As a computational problem, global weather prediction is comparable to the simulation of the human brain and of the evolution of the early Universe, and it is performed every day at major operational centres across the world.

  12. 49 CFR 222.38 - Can a quiet zone be created in the Chicago Region?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Can a quiet zone be created in the Chicago Region... § 222.38 Can a quiet zone be created in the Chicago Region? Public authorities that are eligible to establish quiet zones under this part may create New Quiet Zones or New Partial Quiet Zones in the...

  13. 49 CFR 222.38 - Can a quiet zone be created in the Chicago Region?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Can a quiet zone be created in the Chicago Region... § 222.38 Can a quiet zone be created in the Chicago Region? Public authorities that are eligible to establish quiet zones under this part may create New Quiet Zones or New Partial Quiet Zones in the...

  14. 49 CFR 222.38 - Can a quiet zone be created in the Chicago Region?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Can a quiet zone be created in the Chicago Region... § 222.38 Can a quiet zone be created in the Chicago Region? Public authorities that are eligible to establish quiet zones under this part may create New Quiet Zones or New Partial Quiet Zones in the...

  15. 49 CFR 222.38 - Can a quiet zone be created in the Chicago Region?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Can a quiet zone be created in the Chicago Region... § 222.38 Can a quiet zone be created in the Chicago Region? Public authorities that are eligible to establish quiet zones under this part may create New Quiet Zones or New Partial Quiet Zones in the...

  16. 49 CFR 222.38 - Can a quiet zone be created in the Chicago Region?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Can a quiet zone be created in the Chicago Region... § 222.38 Can a quiet zone be created in the Chicago Region? Public authorities that are eligible to establish quiet zones under this part may create New Quiet Zones or New Partial Quiet Zones in the...

  17. Quiet Sun Explosive Events: Jets, Splashes, and Eruptions

    NASA Astrophysics Data System (ADS)

    Innes, D. E.; Teriaca, L.

    2013-02-01

    Explosive events appear as broad non-Gaussian wings in the line profiles of small transition-region phenomena. Images from the Solar Dynamics Observatory (SDO) give a first view of the plasma dynamics at the sites of explosive events seen simultaneously in O vi spectra of a region of quiet Sun, taken with the ultraviolet spectrometer Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard the Solar and Heliospheric Observatory (SOHO). Distinct event bursts were seen either at the junction of supergranular network cells or near emerging flux. Three are described in the context of their surrounding transition region (304 Å) and coronal (171 Å) activity. One showed plasma ejections from an isolated pair of sites, with a time lag of 50 seconds between events. At the site where the later explosive event was seen, the extreme ultraviolet (EUV) images show a hot core surrounded by a small, expanding ring of chromospheric emission, which we interpret as a "splash." The second explosive-event burst was related to flux cancellation, inferred from Helioseismic and Magnetic Imager (HMI) magnetograms, and a coronal dimming surrounded by a ring of bright EUV emission with explosive events at positions where the spectrometer slit crossed the bright ring. The third series of events occurred at the base of a slow, small coronal mass ejection (mini-CME). All events studied here imply jet-like flows probably triggered by magnetic reconnection at supergranular junctions. Events come from sites close to the footpoints of jets seen in Atmospheric Imaging Assembly (AIA) images, and possibly from the landing site of high-velocity flows. They are not caused by rapid rotation in spicules.

  18. Microwave properties of a quiet sea

    NASA Technical Reports Server (NTRS)

    Stacey, J.

    1985-01-01

    The microwave flux responses of a quiet sea are observed at five microwave frequencies and with both horizontal and vertical polarizations at each frequency--a simultaneous 10 channel receiving system. The measurements are taken from Earth orbit with an articulating antenna. The 10 channel responses are taken simultaneously since they share a common articulating collector with a multifrequency feed. The plotted flux responses show: (1) the effects of the relative, on-axis-gain of the collecting aperture for each frequency; (2) the effects of polarization rotation in the output responses of the receive when the collecting aperture mechanically rotates about a feed that is fixed; (3) the difference between the flux magnitudes for the horizontal and vertical channels, at each of the five frequencies, and for each pointing position, over a 44 degree scan angle; and (4) the RMS value of the clutter--as reckoned over the interval of a full swath for each of the 10 channels. The clutter is derived from the standard error of estimate of the plotted swath response for each channel. The expected value of the background temperature is computed for each of the three quiet seas. The background temperature includes contributions from the cosmic background, the downwelling path, the sea surface, and the upwelling path.

  19. Electron density profiles in the quiet lower ionosphere based on the results of modeling and experimental data

    NASA Astrophysics Data System (ADS)

    Barabash, V.; Osepian, A.; Dalin, P.; Kirkwood, S.

    2012-09-01

    The theoretical PGI (Polar Geophysical Institute) model for the quiet lower ionosphere has been applied for computing the ionization rate and electron density profiles in the summer and winter D-region at solar zenith angles less than 80° and larger than 99° under steady state conditions. In order to minimize possible errors in estimation of ionization rates provided by solar electromagnetic radiation and to obtain the most exact values of electron density, each wavelength range of the solar spectrum has been divided into several intervals and the relations between the solar radiation intensity at these wavelengths and the solar activity index F10.7 have been incorporated into the model. Influence of minor neutral species (NO, H2O, O, O3) concentrations on the electron number density at different altitudes of the sunlit quiet D-region has been examined. The results demonstrate that at altitudes above 70 km, the modeled electron density is most sensitive to variations of nitric oxide concentration. Changes of water vapor concentration in the whole altitude range of the mesosphere influence the electron density only in the narrow height interval 73-85 km. The effect of the change of atomic oxygen and ozone concentration is the least significant and takes place only below 70 km. Model responses to changes of the solar zenith angle, solar activity (low-high) and season (summer-winter) have been considered. Modeled electron density profiles have been evaluated by comparison with experimental profiles available from the rocket measurements for the same conditions. It is demonstrated that the theoretical model for the quiet lower ionosphere is quite effective in describing variations in ionization rate, electron number density and effective recombination coefficient as functions of solar zenith angle, solar activity and season. The model may be used for solving inverse tasks, in particular, for estimations of nitric oxide concentration in the mesosphere.

  20. The "Quiet" Troubles of Low-Income Children

    ERIC Educational Resources Information Center

    Weissbourd, Richard

    2009-01-01

    Most of the troubles poor at-risk children have are not "loud" problems like disruptive behavior or gang involvement. They are "quiet." The range of these problems is vast. Hunger, dehydration, asthma, obesity, and hearing problems can all insidiously trip children up in school. Some quiet problems are psychological--depression, anxiety, the fear…

  1. Mired in the Shadows: Quiet Students in Secondary Schools

    ERIC Educational Resources Information Center

    Thompson, Greg; Bell, James

    2011-01-01

    Quiet students are a feature of the organisation of secondary schools. Using qualitative methods and Deleuzean conceptualisations of modern subjectivity, this paper explores the ways that quiet students negotiate the terrain of their school. These negotiations often seem to produce a self that is trapped rather than a subject who seizes…

  2. Quiet swimming at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Andersen, Anders; Wadhwa, Navish; Kiorboe, Thomas

    2015-11-01

    Planktonic organisms that inhabit the water masses of the oceans are faced with a dilemma: They need to swim to find food and mates, but by swimming they inevitably create flow disturbances that attract predators. We discuss that planktonic swimmers can reduce the flow disturbances due to their swimming, simply by appropriately arranging their propulsion apparatus. Motivated by recent experiments, we demonstrate that a three-Stokeslet model of a breast stroke swimmer is an example of a quiet swimmer. We show that the flow disturbances around the organism in both the near field and the far field are small in comparison with simple pullers and pushers, and we find that the far field power laws are valid surprisingly close to the organism. Breast stroke swimming may thus be advantageous, and this might explain why it is very common in the world of the plankton.

  3. Some effects of quiet geomagnetic field changes upon values used for main field modeling

    USGS Publications Warehouse

    Campbell, W.H.

    1987-01-01

    The effects of three methods of data selection upon the assumed main field levels for geomagnetic observatory records used in main field modeling were investigated for a year of very low solar-terrestrial activity. The first method concerned the differences between the year's average of quiet day field values and the average of all values during the year. For H these differences were 2-3 gammas, for D they were -0.04 to -0.12???, for Z the differences were negligible. The second method of selection concerned the effects of the daytime internal Sq variations upon the daily mean values of field. The midnight field levels when the Sq currents were a minimum deviated from the daily mean levels by as much as 4-7 gammas in H and Z but were negligible for D. The third method of selection was designed to avoid the annual and semi-annual quiet level changes of field caused by the seasonal changes in the magnetosphere. Contributions from these changes were found to be as much as 4-7 gammas in quiet years and expected to be greater than 10 gammas in active years. Suggestions for improved methods of improved data selection in main field modeling are given. ?? 1987.

  4. An alternative way to identify local geomagnetically quiet days: a case study using wavelet analysis

    NASA Astrophysics Data System (ADS)

    Klausner, Virginia; Reinaldo Rodriguez Papa, Andrés; Cândido, Cláudia Maria Nicole; Oliveira Domingues, Margarete; Mendes, Odim

    2016-04-01

    This paper proposes a new method to evaluate geomagnetic activity based on wavelet analysis during the solar minimum activity (2007). In order to accomplish this task, a newly developed algorithm called effectiveness wavelet coefficient (EWC) was applied. Furthermore, a comparison between the 5 geomagnetically quiet days determined by the Kp-based method and by wavelet-based method was performed. This paper provides a new insight since the geomagnetic activity indexes are mostly designed to quantify the extent of disturbance rather than the quietness. The results suggest that the EWC can be used as an alternative tool to accurately detect quiet days, and consequently, it can also be used as an alternative to determine the Sq baseline to the current Kp-based 5 quietest days method. Another important aspect of this paper is that most of the quietest local wavelet candidate days occurred in an interval 2 days prior to the high-speed-stream-driven storm events. In other words, the EWC algorithm may potentially be used to detect the quietest magnetic activity that tends to occur just before the arrival of high-speed-stream-driven storms.

  5. CORONAL SEISMOLOGY USING EIT WAVES: ESTIMATION OF THE CORONAL MAGNETIC FIELD STRENGTH IN THE QUIET SUN

    SciTech Connect

    West, M. J.; Zhukov, A. N.; Dolla, L.; Rodriguez, L.

    2011-04-01

    Coronal EIT waves have been observed for many years. The nature of EIT waves is still contentious, however, there is strong evidence that some of them might be fast magnetosonic waves, or at least have a fast magnetosonic wave component. The fast magnetosonic wave speed is formed from two components; the Alfven speed (magnetic) and the sound speed (thermal). By making measurements of the wave speed, coronal density and temperature it is possible to calculate the quiet-Sun coronal magnetic field strength through coronal seismology. In this paper, we investigate an EIT wave observed on 2009 February 13 by the SECCHI/EUVI instruments on board the STEREO satellites. The wave epicenter was observed at disk center in the STEREO B (Behind) satellite. At this time, the STEREO satellites were separated by approximately 90 deg., and as a consequence the STEREO A (Ahead) satellite observed the wave on the solar limb. These observations allowed us to make accurate speed measurements of the wave. The background coronal density was derived through Hinode/Extreme-ultraviolet Imaging Spectrometer observations of the quiet Sun and the temperature was estimated through the narrow temperature response in the EUVI bandpasses. The density, temperature, and speed measurements allowed us to estimate the quiet-Sun coronal magnetic field strength to be approximately 0.7 {+-} 0.7 G.

  6. Quiet Sun coronal heating: A statistical model

    NASA Astrophysics Data System (ADS)

    Krasnoselskikh, V.; Podladchikova, O.; Lefebvre, B.; Vilmer, N.

    2002-02-01

    Recent observations of Krucker & Benz (\\cite{Krucker98}) give strong support to Parker's hypothesis (\\cite∥) that small-scale dissipative events make up the main contribution to quiet Sun coronal heating. They also showed that these small-scale events are associated not only with the magnetic network, but also with the cell interiors (Benz & Krucker \\cite{Benz98}). Taking into account in addition the results of the analysis performed by Priest with co-authors (\\cite{pr1}) who demonstrated that the heating is quasi-homogeneous along the arcs, we come to the conclusion that the sources driving these dissipative events are also small-scale sources. Typically they are of the order of or smaller than the linear scale of the events observed, that is <2000 km. To describe statistical properties of quiet Sun corona heating by microflares, nanoflares, and even smaller events, we consider a cellular automata model subject to uniform small-scale driving and dissipation. The model consists of two elements, the magnetic field source supposed to be associated with the small scale hydrodynamic turbulence convected from the photosphere and local dissipation of small scale currents. The dissipation is assumed to be provided by either anomalous resistivity, when the current density exceeds a certain threshold value, or by the magnetic reconnection. The main problem considered is how the statistical characteristics of dissipated energy flow depend upon characteristics of the magnetic field source and on physical mechanism responsible for the magnetic field dissipation. As the threshold value of current is increased, we observe the transition from Gaussian statistics to power-law type. In addition, we find that the dissipation provided by reconnection results in stronger deviations from Gaussian distribution.

  7. HF radar observations of ionospheric backscatter during geomagnetically quiet periods

    NASA Astrophysics Data System (ADS)

    Kane, T. A.; Makarevich, R. A.; Devlin, J. C.

    2012-01-01

    The quiet-time coherent backscatter from the F-region observed by the Tasman International Geospace Environment Radar (TIGER) Bruny Island HF radar is analysed statistically in order to determine typical trends and controlling factors in the ionospheric echo occurrence. A comparison of the F-region peak density values from the IRI-2007 model and ionosonde measurements in the vicinity of the radar's footprint shows a very good agreement, particularly at subauroral and auroral latitudes, and model densities within the radar's footprint are used in the following analyses. The occurrence of F-region backscatter is shown to exhibit distinct diurnal, seasonal and solar cycle variations and these are compared with model trends in the F-region peak electron density and Pedersen conductance of the underlying ionosphere. The solar cycle effects in occurrence are demonstrated to be strong and more complex than a simple proportionality on a year-to-year basis. The diurnal and seasonal effects are strongly coupled to each other, with diurnal trends exhibiting a systematic gradual variation from month to month that can be explained when both electron density and conductance trends are considered. During the night, the echo occurrence is suggested to be controlled directly by the density conditions, with a direct proportionality observed between the occurrence and peak electron density. During the day, the echo occurrence appears to be controlled by both conductance and propagation conditions. It is shown that the range of echo occurrence values is smaller for larger conductances and that the electron density determines what value the echo occurrence takes in that range. These results suggest that the irregularity production rates are significantly reduced by the highly conducting E layer during the day while F-region density effects dominate during the night.

  8. Response of Granulation to Small-scale Bright Features in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Anđić, A.; Chae, J.; Goode, P. R.; Cao, W.; Ahn, K.; Yurchyshyn, V.; Abramenko, V.

    2011-04-01

    We detected 2.8 bright points (BPs) per Mm2 in the quiet Sun with the New Solar Telescope at Big Bear Solar Observatory, using the TiO 705.68 nm spectral line at an angular resolution ~0farcs1 to obtain a 30 minute data sequence. Some BPs formed knots that were stable in time and influenced the properties of the granulation pattern around them. The observed granulation pattern within ~3'' of knots presents smaller granules than those observed in a normal granulation pattern, i.e., around the knots a suppressed convection is detected. Observed BPs covered ~5% of the solar surface and were not homogeneously distributed. BPs had an average size of 0farcs22, they were detectable for 4.28 minutes on average, and had an averaged contrast of 0.1% in the deep red TiO spectral line.

  9. RESPONSE OF GRANULATION TO SMALL-SCALE BRIGHT FEATURES IN THE QUIET SUN

    SciTech Connect

    Andic, A.; Chae, J.; Goode, P. R.; Cao, W.; Ahn, K.; Yurchyshyn, V.; Abramenko, V.

    2011-04-10

    We detected 2.8 bright points (BPs) per Mm{sup 2} in the quiet Sun with the New Solar Telescope at Big Bear Solar Observatory, using the TiO 705.68 nm spectral line at an angular resolution {approx}0.''1 to obtain a 30 minute data sequence. Some BPs formed knots that were stable in time and influenced the properties of the granulation pattern around them. The observed granulation pattern within {approx}3'' of knots presents smaller granules than those observed in a normal granulation pattern, i.e., around the knots a suppressed convection is detected. Observed BPs covered {approx}5% of the solar surface and were not homogeneously distributed. BPs had an average size of 0.''22, they were detectable for 4.28 minutes on average, and had an averaged contrast of 0.1% in the deep red TiO spectral line.

  10. SOHO reveals violent action on the quiet Sun

    NASA Astrophysics Data System (ADS)

    1996-05-01

    SOHO's scientists are impressed by the vigorous action that they see going on every day, because the Sun is in the very quietest phase of its eleven-year cycle of activity. To ground-based observatories it appears extremely calm just now. The early indications of SOHO's performance amply justify the creation of a sungazing spacecraft capable of observing ultraviolet emissions that are blotted out by the Earth's atmosphere. Apart from the imager, two ultraviolet spectrometers and an ultraviolet coronagraph (an imager for the outer atmosphere) are busy analysing the violent processes at a wide range of wavelengths. Between them, these instruments should cure long-lasting ignorance concerning the Sun, especially about why the atmosphere is so hot and what drives the solar wind that blows non-stop into the Solar System. Scientists from other experimental teams use SOHO to explore the Sun from its deep interior to the far reaches of the solar wind. They have watched the supposedly quiet Sun belching huge masses of gas into space. They have mapped a hole burnt by the solar wind in a breeze of gas coming from the stars. And they have detected currents of gas flowing just below the visible surface. SOHO is a project of international cooperation between the European Space Agency and NASA. The spacecraft was built in Europe and instrumented by scientists on both sides of the Atlantic. NASA launched SOHO on 2 December 1995, and also provides the ground stations and an operations centre near Washington. The first results are the more remarkable because SOHO arrived at its vantage point 1,500,000 kilometres out in space only in February, and formally completed its commissioning on 16 April. It has a long life ahead of it. All scientific instruments are working well. The luminosity oscillation imager belonging to the VIRGO experiment had trouble with its lens cover. When opened, the cover rebounded on its hinges and closed again. Commands were devised that gave a shorter impulse

  11. Day-To Variability of the Quiet-Time Equatorial Electrojet and Post-Sunset Occurrence of Equatorial Ionospheric Scintillations

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Archana; Okpala, Kingsley

    Strength of the equatorial electrojet (EEJ) derived from measurements of the horizontal component H of the geomagnetic field at an equatorial station, Tirunelveli, and a low-latitude station Alibag, outside the influence of the EEJ, on International quiet (IQ) days of the years 2001-2005, have been subjected to Principal Component Analysis to determine the principal components (PCs) that describe the variability of the quiet-time EEJ. It is found that the first three PCs together account for 94% of the variability of the EEJ observed during the IQ days of this period. PC1 itself represents about 64% of the EEJ variations, while PC2 and PC3 respectively account for 23% and 7% of the quiet-time variability of the EEJ during these years when the daily adjusted 10.7 cm solar flux, Sa, decreased from values exceeding 200 to around 100. The temporal structure of PC1 is such that it contributes only to the variability of the normal electrojet and cannot explain events such as the counter-electrojet (CEJ). A model is constructed for quiet-day PC1 scores as a function of day number and solar activity to describe a major part of the variability of the normal quiet-time EEJ. However, the CEJ and other 'abnormal' variations such as an afternoon enhancement of the EEJ, are only associated with PC2 and PC3. The quiet-day PC2 and PC3 scores obtained in this study, therefore, indicate the influence of forcing of the equatorial ionosphere from below. The day-to-day variability of the quiet-time pre-reversal enhancement of the post-sunset equatorial F region zonal electric field, which plays a crucial role in the occurrence of scintillation-producing equatorial ionospheric irregularities, is also influenced by forcing from below. In this context, occurrence of scintillations on a 251 MHz signal, transmitted from a geostationary satellite, and recorded at Tirunelveli, is studied in relation to the PC scores, which describe the variability of the EEJ, in order to identify a possible

  12. Overview of the Arizona Quiet Pavement Program

    NASA Astrophysics Data System (ADS)

    Donavan, Paul; Scofield, Larry

    2005-09-01

    The Arizona Quiet Pavement Pilot Program (QP3) was initially implemented to reduce highway related traffic noise by overlaying most of the Phoenix metropolitan area Portland cement concrete pavement with a one inch thick asphalt rubber friction coarse. With FHWA support, this program represents the first time that pavement surface type has been allowed as a noise mitigation strategy on federally funded projects. As a condition of using pavement type as a noise mitigation strategy, ADOT developed a ten-year, $3.8 million research program to evaluate the noise reduction performance over time. Historically, pavement surface type was not considered a permanent solution. As a result, the research program was designed to specifically address this issue. Noise performance is being evaluated through three means: (1) conventional roadside testing within the roadway corridor (e.g., far field measurements within the right-of-way) (2) the use of near field measurements, both close proximity (CPX) and sound intensity (SI); and (3) far field measurements obtained beyond the noise barriers within the surrounding neighborhoods. This paper provides an overview of the program development, presents the research conducted to support the decision to overlay the urban freeway, and the status of current research.

  13. Quiet swimming at low Reynolds number.

    PubMed

    Andersen, Anders; Wadhwa, Navish; Kiørboe, Thomas

    2015-04-01

    The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws are valid surprisingly close to the organism. Finally, we discuss point force models as a general framework for hypothesis generation and experimental exploration of fluid mediated predator-prey interactions in the planktonic world. PMID:25974532

  14. Prognostic Analysis of the Tactical Quiet Generator

    SciTech Connect

    Hively, Lee M

    2008-09-01

    The U.S. Army needs prognostic analysis of mission-critical equipment to enable condition-based maintenance before failure. ORNL has developed and patented prognostic technology that quantifies condition change from noisy, multi-channel, time-serial data. This report describes an initial application of ORNL's prognostic technology to the Army's Tactical Quiet Generator (TQG), which is designed to operate continuously at 10 kW. Less-than-full power operation causes unburned fuel to accumulate on internal components, thereby degrading operation and eventually leading to failure. The first objective of this work was identification of easily-acquired, process-indicative data. Two types of appropriate data were identified, namely output-electrical current and voltage, plus tri-axial acceleration (vibration). The second objective of this work was data quality analysis to avoid the garbage-in-garbage-out syndrome. Quality analysis identified more than 10% of the current data as having consecutive values that are constant, or that saturate at an extreme value. Consequently, the electrical data were not analyzed further. The third objective was condition-change analysis to indicate operational stress under non-ideal operation and machine degradation in proportion to the operational stress. Application of ORNL's novel phase-space dissimilarity measures to the vibration power quantified the rising operational stress in direct proportion to the less-than-full-load power. We conclude that ORNL's technology is an excellent candidate to meet the U.S. Army's need for equipment prognostication.

  15. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-Quiet Zones § 222.51 Under what conditions will quiet zone status be terminated? (a) New Quiet Zones... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public... 49 Transportation 4 2013-10-01 2013-10-01 false Under what conditions will quiet zone status...

  16. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-Quiet Zones § 222.51 Under what conditions will quiet zone status be terminated? (a) New Quiet Zones... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public... 49 Transportation 4 2014-10-01 2014-10-01 false Under what conditions will quiet zone status...

  17. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-Quiet Zones § 222.51 Under what conditions will quiet zone status be terminated? (a) New Quiet Zones... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public... 49 Transportation 4 2011-10-01 2011-10-01 false Under what conditions will quiet zone status...

  18. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-Quiet Zones § 222.51 Under what conditions will quiet zone status be terminated? (a) New Quiet Zones... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public... 49 Transportation 4 2012-10-01 2012-10-01 false Under what conditions will quiet zone status...

  19. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-Quiet Zones § 222.51 Under what conditions will quiet zone status be terminated? (a) New Quiet Zones... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public... 49 Transportation 4 2010-10-01 2010-10-01 false Under what conditions will quiet zone status...

  20. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    A study of quiet turbofan short takeoff aircraft for short haul air transportation was conducted. The objectives of the study were to: (1) define representative aircraft configurations, characteristics, and costs associated with their development, (2) identify critical technology and technology related problems to be resolved in successful introduction of representative short haul aircraft, (3) determine relationships between quiet short takeoff aircraft and the economic and social viability of short haul, and (4) identify high payoff technology areas.

  1. Quiet Spike (TM) Build-Up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    Flight tests of Gulfstream Aerospace Corporation s Quiet Spike(TM) hardware were recently completed on the NASA Dryden Flight Research Center F-15B airplane. NASA Dryden uses a modified F-15B airplane as a testbed aircraft to cost-effectively fly flight research experiments that are typically mounted underneath the F-15B airplane, along the fuselage centerline. For the Quiet Spike(TM) experiment, however, instead of a centerline mounting, a relatively long forward-pointing boom was attached to the radar bulkhead of the F-15B airplane. The Quiet Spike(TM) experiment is a stepping-stone to airframe structural morphing technologies designed to mitigate the sonic-boom strength of business jets over land. The Quiet Spike(TM) boom is a concept in which an aircraft's noseboom would be extended prior to supersonic acceleration. This morphing effectively lengthens the aircraft, thus reducing the peak sonic-boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, noncoalescing shocklets. Prior to flying the Quiet Spike(TM) experiment on the F-15B airplane several ground vibration tests were required to understand the Quiet Spike(TM) modal characteristics and coupling effects with the F-15B airplane. However, due to the flight hardware availability and compressed schedule requirements, a "traditional" ground vibration test of the mated F-15B Quiet Spike(TM) ready-for-flight configuration did not leave sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. This paper provides an overview of each phase of the "nontraditional" ground vibration testing completed for the Quiet Spike(TM) project which includes the test setup details, instrumentation layout, and modal results obtained in support of the structural dynamic modeling and flutter analyses.

  2. Aurora at quiet magnetospheric conditions: Repeatability and dipole tilt angle dependence. (Reannouncement with new availability information)

    SciTech Connect

    Oznovich, I.; Eastes, R.W.; Huffman, R.E.; Tur, M.; Glaser, I.

    1993-03-01

    Is there a magnetospheric ground state? Do the position and size of the auroral oval depend on the magnetic dipole tilt angle at quiet magnetospheric conditions? In order to address these questions, northern hemisphere images of the aurora at 1356 A, obtained by Polar BEAR at solar minimum (beginning of 1987), were related to high temporal resolution IMP 8 measurements of the interplanetary magnetic field, to solar wind velocity, and to the ground-based activity index Kp. The first problem was addressed by a two-dimensional correlation study of the repeatability of auroral emissions in corrected geomagnetic space at conditions of minimum energy transfer from the magnetosphere. The correlation measure of auroral images was 0.6--0.85. Error simulations indicate that given the uncertainties in pixel position and intensity, the maximum expected value of the correlation measure is 0.65-0.9. The notion of a ground state magnetosphere is therefore supported by this data. Repeatability was found at the same level regardless of time or reconfigurations of the magnetosphere between images and independent of magnetic time sector. The second problem was addressed by relating latitudinal shifts of the aurora with dipole tilt angle without resorting to auroral boundary specification. The authors data indicate that the latitude of the continuous aurora is related to the dipole tilt angle at quiet magnetospheric conditions. In the winter hemisphere a 10 deg increase in the dipole tilt angle causes a 1 deg decrease (increase) in the latitude of auroral emissions at noon (midnight).

  3. Stiffness control of balance in quiet standing.

    PubMed

    Winter, D A; Patla, A E; Prince, F; Ishac, M; Gielo-Perczak, K

    1998-09-01

    Our goal was to provide some insights into how the CNS controls and maintains an upright standing posture, which is an integral part of activities of daily living. Although researchers have used simple performance measures of maintenance of this posture quite effectively in clinical decision making, the mechanisms and control principles involved have not been clear. We propose a relatively simple control scheme for regulation of upright posture that provides almost instantaneous corrective response and reduces the operating demands on the CNS. The analytic model is derived and experimentally validated. A stiffness model was developed for quiet standing. The model assumes that muscles act as springs to cause the center-of-pressure (COP) to move in phase with the center-of-mass (COM) as the body sways about some desired position. In the sagittal plane this stiffness control exists at the ankle plantarflexors, in the frontal plane by the hip abductors/adductors. On the basis of observations that the COP-COM error signal continuously oscillates, it is evident that the inverted pendulum model is severely underdamped, approaching the undamped condition. The spectrum of this error signal is seen to match that of a tuned mass, spring, damper system, and a curve fit of this "tuned circuit" yields omega n the undamped natural frequency of the system. The effective stiffness of the system, Ke, is then estimated from Ke = I omega n2, and the damping B is estimated from B = BW X I, where BW is the bandwidth of the tuned response (in rad/s), and I is the moment of inertia of the body about the ankle joint. Ten adult subjects were assessed while standing quietly at three stance widths: 50% hip-to-hip distance, 100 and 150%. Subjects stood for 2 min in each position with eyes open; the 100% stance width was repeated with eyes closed. In all trials and in both planes, the COP oscillated virtually in phase (within 6 ms) with COM, which was predicted by a simple 0th order spring

  4. Two-Component Fitting of Coronal-Hole and Quiet-Sun He I 1083 Spectra

    NASA Technical Reports Server (NTRS)

    Jones, Harrison P.; Malanushenko, Elena V.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present reduction techniques and first results for detailed fitting of solar spectra obtained with the NASA/National Solar Observatory Spectromagnetograph (NASA/NSO SPM over a 2 nm bandpass centered on the He 1 1083 nm line. The observation for this analysis was a spectra-spectroheliogram obtained at the NSO/Kitt Peak Vacuum Telescope (KPVT) on 00 Apr 17 at 21:46 UT spanning an area of 512 x 900 arc-seconds; the field of view included a coronal hole near disk center as well as surrounding quiet sun. Since the He I line is very weak and blended with nearby solar and telluric lines, accurate determination of the continuum intensity as a function of wavelength is crucial. We have modified the technique of Malanushenko {\\it et al.) (1992; {\\it AA) (\\bf 259), 567) to tie regions of continuua and the wings of spectral lines which show little variation over the image to standard reference spectra such as the NSO Fourier Transform Spectrometer atlas (Wallace {\\it et al). 1993; NSO Tech Report \\#93-001). We performed detailed least-squares fits of spectra from selected areas, accounting for all the known telluric and solar absorbers in the spectral bandpass. The best physically consistent fits to the Helium lines were obtained with Gaussian profiles from two components (one ''cool'', characteristic of the upper chromosphere; one ''hot'', representing the cool transition region at 2-3 x 10$^{4)$ K). In the coronal hole, the transition-region component, shifted by 6-7 km/s to the blue, is mildly dominant, consistent with mass outflow as suggested by Dupree {\\it et all. (1996; {\\it Ap. J.}-{\\bf 467), 121). In quiet-sun spectra there is less evidence of outward flow, and the chromospheric component is more important. All our fitted spectra show a very weak unidentified absorption feature at 1082.880 nm in the red wing of the nearby Si I line.

  5. Dynamic signatures of quiet sun magnetic fields

    NASA Technical Reports Server (NTRS)

    Martin, S. F.

    1983-01-01

    The collision and disappearance of opposite polarity fields is observed most frequently at the borders of network cells. Due to observational limitations, the frequency, magnitude, and spatial distribution of magnetic flux loss have not yet been quantitatively determined at the borders or within the interiors of the cells. However, in agreement with published hypotheses of other authors, the disapperance of magnetic flux is speculated to be a consequence of either gradual or rapid magnetic reconnection which could be the means of converting magnetic energy into the kinetic, thermal, and nonthermal sources of energy for microflares, spicules, the solar wind, and the heating of the solar corona.

  6. First simultaneous SST/CRISP and IRIS observations of a small-scale quiet Sun vortex

    NASA Astrophysics Data System (ADS)

    Park, S.-H.; Tsiropoula, G.; Kontogiannis, I.; Tziotziou, K.; Scullion, E.; Doyle, J. G.

    2016-02-01

    Context. Ubiquitous small-scale vortices have recently been found in the lower atmosphere of the quiet Sun in state-of-the-art solar observations and in numerical simulations. Aims: We investigate the characteristics and temporal evolution of a granular-scale vortex and its associated upflows through the photosphere and chromosphere of a quiet Sun internetwork region. Methods: We analyzed high spatial and temporal resolution ground- and spaced-based observations of a quiet Sun region. The observations consist of high-cadence time series of wideband and narrowband images of both Hα 6563 Å and Ca II 8542 Å lines obtained with the CRisp Imaging SpectroPolarimeter (CRISP) instrument at the Swedish 1-m Solar Telescope (SST), as well as ultraviolet imaging and spectral data simultaneously obtained by the Interface Region Imaging Spectrograph (IRIS). Results: A small-scale vortex is observed for the first time simultaneously in Hα, Ca II 8542 Å, and Mg II k lines. During the evolution of the vortex, Hα narrowband images at -0.77 Å and Ca II 8542 Å narrowband images at -0.5 Å, and their corresponding Doppler signal maps, clearly show consecutive high-speed upflow events in the vortex region. These high-speed upflows with a size of 0.5-1 Mm appear in the shape of spiral arms and exhibit two distinctive apparent motions in the plane of sky for a few minutes: (1) a swirling motion with an average speed of 13 km s-1 and (2) an expanding motion at a rate of 4-6 km s-1. Furthermore, the spectral analysis of Mg II k and Mg II subordinate lines in the vortex region indicates an upward velocity of up to ~8 km s-1 along with a higher temperature compared to the nearby quiet Sun chromosphere. Conclusions: The consecutive small-scale vortex events can heat the upper chromosphere by driving continuous high-speed upflows through the lower atmosphere. Movies associated to Figs. 2 and 3 are available at http://www.aanda.org

  7. OBSERVATIONS OF THE INTERACTION OF ACOUSTIC WAVES AND SMALL-SCALE MAGNETIC FIELDS IN A QUIET SUN

    SciTech Connect

    Chitta, Lakshmi Pradeep; Kariyappa, R.; Jain, Rekha; Jefferies, Stuart M. E-mail: rkari@iiap.res.in E-mail: stuartj@ifa.hawaii.edu

    2012-01-10

    The effect of the magnetic field on photospheric intensity and velocity oscillations at the sites of small-scale magnetic fields (SMFs) in a quiet Sun near the solar disk center is studied. We use observations made by the G-band filter in the Solar Optical Telescope on board Hinode for intensity oscillations; Doppler velocity, magnetic field, and continuum intensity are derived from an Ni I photospheric absorption line at 6767.8 A using the Michelson Doppler Imager on board the Solar and Heliospheric Observatory. Our analysis shows that both the high-resolution intensity observed in the G band and velocity oscillations are influenced by the presence of a magnetic field. While intensity oscillations are suppressed at all frequencies in strong magnetic field regions compared to weak magnetic field regions, velocity oscillations show an enhancement of power in the frequency band 5.5-7 mHz. We find that there is a drop of 20%-30% in the p-mode power of velocity oscillations within the SMFs when compared to the regions surrounding them. Our findings indicate that the nature of the interaction of acoustic waves with the quiet Sun SMFs is similar to that of large-scale magnetic fields in active regions. We also report the first results of the center-to-limb variation of such effects using the observations of the quiet Sun from the Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO). The independent verification of these interactions using SDO/HMI suggests that the velocity power drop of 20%-30% in p-modes is fairly constant across the solar disk.

  8. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  9. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  10. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  11. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  12. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  13. A novel acoustically quiet coil for neonatal MRI system

    PubMed Central

    Ireland, Christopher M.; Giaquinto, Randy O.; Loew, Wolfgang; Tkach, Jean A.; Pratt, Ronald G.; Kline-Fath, Beth M.; Merhar, Stephanie L.; Dumoulin, Charles L.

    2015-01-01

    MRI acoustic exposure has the potential to elicit physiological distress and impact development in preterm and term infants. To mitigate this risk, a novel acoustically quiet coil was developed to reduce the sound pressure level experienced by neonates during MR procedures. The new coil has a conventional high-pass birdcage RF design, but is built on a framework of sound abating material. We evaluated the acoustic and MR imaging performance of the quiet coil and a conventional body coil on two small footprint NICU MRI systems. Sound pressure level and frequency response measurements were made for six standard clinical MR imaging protocols. The average sound pressure level, reported for all six imaging pulse sequences, was 82.2 dBA for the acoustically quiet coil, and 91.1 dBA for the conventional body coil. The sound pressure level values measured for the acoustically quiet coil were consistently lower, 9 dBA (range 6-10 dBA) quieter on average. The acoustic frequency response of the two coils showed a similar harmonic profile for all imaging sequences. However, the amplitude was lower for the quiet coil, by as much as 20 dBA. PMID:26457072

  14. Field Line Resonances in Quiet and Disturbed Time Three-dimensional Magnetospheres

    SciTech Connect

    C.Z. Cheng; S. Zaharia

    2002-05-30

    Numerical solutions for field line resonances (FLR) in the magnetosphere are presented for three-dimensional equilibrium magnetic fields represented by two Euler potentials as B = -j Y -a, where j is the poloidal flux and a is a toroidal angle-like variable. The linearized ideal-MHD equations for FLR harmonics of shear Alfvin waves and slow magnetosonic modes are solved for plasmas with the pressure assumed to be isotropic and constant along a field line. The coupling between the shear Alfvin waves and the slow magnetosonic waves is via the combined effects of geodesic magnetic field curvature and plasma pressure. Numerical solutions of the FLR equations are obtained for a quiet time magnetosphere as well as a disturbed time magnetosphere with a thin current sheet in the near-Earth region. The FLR frequency spectra in the equatorial plane as well as in the auroral latitude are presented. The field line length, magnetic field intensity, plasma beta, geodesic curvature and pressure gradient in the poloidal flux surface are important in determining the FLR frequencies. In general, the computed shear Alfvin FLR frequency based on the full MHD model is larger than that based on the commonly adopted cold plasma model in the beq > 1 region. For the quiet time magnetosphere, the shear Alfvin resonance frequency decreases monotonically with the equatorial field line distance, which reasonably explains the harmonically structured continuous spectrum of the azimuthal magnetic field oscillations as a function of L shell in the L is less than or equal to 9RE region. However, the FLR frequency spectrum for the disturbed time magnetosphere with a near-Earth thin current sheet is substantially different from that for the quiet time magnetosphere for R > 6RE, mainly due to shorter field line length due to magnetic field compression by solar wind, reduced magnetic field intensity in the high-beta current sheet region, azimuthal pressure gradient, and geodesic magnetic field

  15. HOMOLOGOUS CYCLONES IN THE QUIET SUN

    SciTech Connect

    Yu, Xinting; Zhang, Jun; Li, Ting; Zhang, Yuzong; Yang, Shuhong E-mail: zjun@nao.cas.cn E-mail: yuzong@nao.cas.cn

    2014-02-20

    Through observations with the Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager, we tracked one rotating network magnetic field (RNF) near the solar equator. It lasted for more than 100 hr, from 2013 February 23 to 28. During its evolution, three cyclones were found to be rooted in this structure. Each cyclone event lasted for about 8 to 10 hr. While near the polar region, another RNF was investigated. It lasted for a shorter time (∼70 hr), from 2013 July 7 to 9. There were two cyclones rooted in the RNF and each lasted for 8 and 11 hr, respectively. For the two given examples, the cyclones have a similar dynamic evolution, and thus we put forward a new term: homologous cyclones. The detected brightening in AIA 171 Å maps indicates the release of energy, which is potentially available to heat the corona.

  16. The quiet-Sun photosphere and chromosphere.

    PubMed

    Rutten, Robert J

    2012-07-13

    The overall structure and the fine structure of the solar photosphere outside active regions are largely understood, except possibly the important roles of a turbulent near-surface dynamo at its bottom, internal gravity waves at its top and small-scale vorticity. Classical one-dimensional static radiation-escape modelling has been replaced by three-dimensional time-dependent magento-hydrodynamic simulations that come closer to reality. The solar chromosphere, in contrast, remains little understood, although its pivotal role in coronal mass and energy loading makes it a principal research area. Its fine structure defines its overall structure, so that hard-to-observe and hard-to-model small-scale dynamical processes are key to understanding. However, both chromospheric observation and chromospheric simulation presently mature towards the required sophistication. Open-field features seem of greater interest than easier-to-see closed-field features. PMID:22665896

  17. A New Observation of the Quiet Sun Soft X-ray (0.5-5 keV) Spectrum

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Woods, T. N.; Stone, J.

    2012-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable with solar activity. While this is particularly true during solar flares, when emission can be enhanced by many orders of magnitude up to gamma-ray energies, even the so-called "quiet Sun" is bright in soft X-rays (SXRs), as the ~1-2 MK ambient plasma of the corona emits significant thermal bremsstrahlung up to ~5 keV. However, the actual solar SXR (0.5-5 keV) spectrum is not well known, particularly during quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include ultra-high-resolution but very narrow-band spectra from crystral spectrometers (e.g. Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g. GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with fair energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and XRS on MESSENGER, although they did not extend below ~1 keV. We present observations of the quiet Sun SXR emission obtained using a new SXR spectrometer flown on the third SDO/EVE underflight calibration rocket (NASA 36.286). The commercial off-the-shelf Amptek X123 silicon drift detector, with an 8-micron Be window and custom aperture, measured the solar SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution (though, due to hardware limitations, with only ~0.12 keV binning) and 2-sec cadence over ~5 minutes on 23 June 2012. Despite the rising solar cycle, activity on 23 June 2012 was abnormally low, with no visible active regions and GOES XRS emission near 2010 levels; we measured no solar counts above ~4 keV during the observation period. We compare our X123 measurements with spectra and broadband irradiances from other instruments, including the SphinX observations during the deep solar minimum of 2009, and with upper limits of >3 keV quiet Sun emission

  18. Principal components of quiet time temporal variability of equatorial and low-latitude geomagnetic fields

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Archana; Okpala, Kingsley C.

    2015-10-01

    Diurnal variations of the horizontal component of the geomagnetic field ΔH on International Quiet days of 1999-2012, measured hourly at two stations in the same longitude zone in the Northern Hemisphere, near and away from the dip equator, have been subjected to principal component analysis. This technique is also applied to the difference ΔHEEJ of ΔH at these two stations, which is attributed to the equatorial electrojet (EEJ). The first three principal components, PC1-PC3, account for 91-96% of the variances in the data. Maximum contribution to the quiet day variations in ΔH around its peak in the morning hours at both the stations, and in the EEJ, comes from the day-to-day variation of the amplitude of PC1. Patterns of day-to-day variations of PC1 amplitudes for the equatorial station and the EEJ are essentially semiannual modulated by solar EUV flux, superimposed on a longer timescale solar EUV flux-dependent trend. Contributions from PC2 and to a lesser extent from PC3 are seen to be responsible for the absence of semiannual variations in ΔH in the afternoon hours at the equatorial station. Distribution of amplitudes of PC2 and PC3 for ΔHEEJ for weak electrojet days shows seasonal features in accordance with greater occurrence of afternoon (morning) counter electrojet during June (December) solstice. During the extended solar minimum, PC3 amplitudes for ΔH at the equatorial station and for the EEJ display annual variation. Possible sources for these seasonal features in the variations of equatorial ΔH are discussed.

  19. STUDY OF SINGLE-LOBED CIRCULAR POLARIZATION PROFILES IN THE QUIET SUN

    SciTech Connect

    Sainz Dalda, A.; Martinez-Sykora, J.; Title, A.; Bellot Rubio, L. E-mail: asainz@lmsal.com

    2012-03-20

    The existence of asymmetries in the circular polarization (Stokes V) profiles emerging from the solar photosphere has been known since the 1970s. These profiles require the presence of a velocity gradient along the line of sight (LOS), possibly associated with gradients of magnetic field strength, inclination, and/or azimuth. We have focused our study on the Stokes V profiles showing extreme asymmetry in the form of only one lobe. Using Hinode spectropolarimetric measurements, we have performed a statistical study of the properties of these profiles in the quiet Sun. We show their spatial distribution, their main physical properties, how they are related with several physical observables, and their behavior with respect to their position on the solar disk. The single-lobed Stokes V profiles occupy roughly 2% of the solar surface. For the first time, we have observed their temporal evolution and have retrieved the physical conditions of the atmospheres from which they emerged using an inversion code implementing discontinuities of the atmospheric parameters along the LOS. In addition, we use synthetic Stokes profiles from three-dimensional magnetoconvection simulations to complement the results of the inversion. The main features of the synthetic single-lobed profiles are in general agreement with the observed ones, lending support to the magnetic and dynamic topologies inferred from the inversion. The combination of all these different analyses suggests that most of the single-lobed Stokes V profiles are signals coming from the magnetic flux emergence and/or submergence processes taking place in small patches in the photosphere of the quiet Sun.

  20. Quiet Sonic Booms: A NASA and Industry Progress Report

    NASA Technical Reports Server (NTRS)

    Larson, David Nils; Martin, Roy; Haering, Edward A.

    2011-01-01

    The purpose of this Oral Presentation is to present a progress report on NASA and Industry efforts related to Quiet Sonic Boom Program activities. This presentation will review changes in aircraft shaping to produce quiet supersonic booms and associated supersonic flight test methods and results. In addition, new flight test profiles have been recently developed that have allowed for the generation of sonic booms of varying intensity. These new flight test profiles have allowed for ground testing of the response of various building structures to sonic booms and the associated public acceptability to various sonic boom intensities. The new flight test profiles and associated ground measurement test methods will be reviewed. Finally, this Oral Presentation will review the International Regulatory requirements that would be involved to change aviation regulation and allow for overland quiet supersonic flight.

  1. High latitude equivalent current systems during extremely quiet times

    NASA Technical Reports Server (NTRS)

    Rostoker, G.; Chen, A. J.; Yasuhara, F.; Akasofu, S.-I.; Kawasaki, K.

    1974-01-01

    The magnetic perturbation patterns in the polar cap and auroral zone regions are obtained for extremely quiet days using two different techniques. It is shown that the form of the equivalent current flow pattern is extremely sensitive to the level of quietness, and that even so-called quiet days are at times disturbed by substorm activity. Certain characteristic equivalent flow not typically observed during substorms is noted in the polar cap, and this flow appears to be associated with effects of polar cap perturbations discussed by Svalgaard (1973). A region of equatorward flow at high latitudes near the dawn meridian, appears to be Hall current driven by an eastward electric field. The dayside sub-auroral zone is dominated by the Sq-current system, while the nightside shows no significant current flow in the absence of substorm activity.

  2. Impacts of Extended Periods of Low Solar Activity on Climate (Abstract)

    NASA Astrophysics Data System (ADS)

    Denig, W. F.

    2016-06-01

    (Abstract only) There has been great interest in determining the length and amplitude of Solar Cycle 24 in recent years, in part due to increasing speculation that the current solar minimum is anomalously quiet and perhaps signaling the beginning of a decreased period of solar activity in the coming decades. We aim to examine the current solar minimum and compare it to previous solar minima in order to: determine if the current minimum shares characteristics with other historically quiet solar minima (sometimes referred to as grand minima); outline the potential consequences of a grand minimum with respect to climate; and predict the future of Solar Cycle 24.

  3. NASA Quiet, Clean General Aviation Turbofan /QCGAT/ program status

    NASA Technical Reports Server (NTRS)

    Bresnahan, D. L.; Sievers, G. K.

    1977-01-01

    Emissions pollution studies, noise studies, and engine performance studies and their place in QCGAT developmental program status are reported. The Lycoming TFE 731 turbofan engine, the GE T700-GE-700 high bypass ratio turbofan, and the AVCO-Lycoming LTS 101 turboshaft engine are prominent candidates in the tests for urban quiet turbofan service. Two phases in the program are characterized. Engine quieting, polluting emissions abatement, and fuel economies are particularly important for the anticipated rise in number of jet propulsion craft using smaller airports adjacent to communities accustomed to low noise/pollution backgrounds.

  4. Quiet geomagnetic field representation for all days and latitudes

    USGS Publications Warehouse

    Campbell, W.H.; Schiffmacher, E.R.; Arora, B.R.

    1992-01-01

    Describes a technique for obtaining the quiet-time geomagnetic field variation expected for all days of the year and distribution of latitudes from a limited set of selected quiet days within a year at a discrete set of locations. A data set of observatories near 75??E longitude was used as illustration. The method relies upon spatial smoothing of the decomposed spectral components. An evaluation of the fidelity of the resulting model shows correlation coefficients usually above 0.9 at the lower latitudes and near 0.7 at the higher latitudes with variations identified as dependent upon season and field element. -from Authors

  5. 3D Simulations of the Quiet Sun Radio Emission at Millimeter and Submillimeter Wavelengths

    NASA Astrophysics Data System (ADS)

    De La Luz, V.; Lara, A.; Mendoza, E.; Shimojo, M.

    2008-07-01

    We present 2D projections of 3D simulations of the quiet-sun radio-emission, at different frequencies on the centimeter- submillimeter wavelength range (specifically at 1.4, 3.9, 17, 34, 43, 110, 212 and 250 GHz). We have built a 3D, spherically symmetric, solar model and solved the classical equation of radiative transfer using quiet-sun temperature and electronic density models. We compare our results with Nobeyama Radio Heliograph observations at 17 GHz. The 3.9 and 43 GHz images will be useful to calibrate the observations of the new 5 meter millimeter telescope (RT5) which is going to be installed at "Sierra Negra" Volcano, in the state of Puebla, México, at an altitude of 4,600 m. over the sea level. This project is a collaboration between Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE) and Universidad Nacional Autónoma de México (UNAM).

  6. Milne-Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

    NASA Astrophysics Data System (ADS)

    Bommier, Véronique

    2016-06-01

    This paper is first devoted to present our method for modeling unresolved magnetic structures in the Milne-Eddington inversion of spectropolarimetric data. The related definitions and other approaches and different used inversion algorithms are recalled for comparison. In a second part, we apply our method to quiet Sun data outside active regions. We obtain the quiet Sun photospheric magnetic field as composed of unresolved opening and connected magnetic flux tubes, which form a loop carpet of field lines. We then analyze the spatial correlation, which we also observed for the magnetic field vector, in terms of flux tube diameter, distance, and field strength. We find that different observations with the Zurich imaging polarimeter and THEMIS polarimeter mounted on the THEMIS telescope give very close results, and we add results also very close derived from HINODE/Solar Optical Telescope/spectropolarimeter observations analyzed with the same method. We obtain a mean flux tube diameter of 30 km, a mean flux tube distance of 230 km, and a mean flux tube magnetic field of 1.3 kG.

  7. Quiet Sun Magnetic Field Evolution Observed with Hinode SOT and IRIS

    NASA Astrophysics Data System (ADS)

    Fischer, C. E.; Bello González, N.; Rezaei, R.

    2016-04-01

    We study two physical processes that can be commonly observed in the quiet sun and involve temporal evolution of the magnetic field: convective collapse and flux cancellation. The aim is to investigate the response of the chromosphere to the magnetic events in the photosphere below. We have calibrated and aligned a co-spatial and co-temporal 3 hour quiet sun time series observed with the Hinode SOT (Solar Optical Telescope) and the IRIS (Interface Region Imaging Spectrograph) satellites. Convective collapse events are identified in the photosphere by inverting spectropolarimetric data and searching for magnetic field intensification, preceded by a downflow and accompanied by the development of a bright point in Ca II H images. We find a corresponding downflow in the low chromosphere as deduced from IRIS Mg II k and h spectra and an ensuing oscillatory velocity pattern. We use magnetograms in the high photosphere to study pairs of magnetic elements involved in flux cancellation and find an increase in the entire quasi-continuum of the IRIS Mg II k and h spectrum following the flux cancellation process and indicating a substantial energy deposit into the lower atmosphere.

  8. UBIQUITOUS ROTATING NETWORK MAGNETIC FIELDS AND EXTREME-ULTRAVIOLET CYCLONES IN THE QUIET SUN

    SciTech Connect

    Zhang Jun; Liu Yang E-mail: yliu@sun.stanford.edu

    2011-11-01

    We present Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) observations of EUV cyclones in the quiet Sun. These cyclones are rooted in the rotating network magnetic fields (RNFs). Such cyclones can last several to more than 10 hr and, at the later phase, they are found to be associated with EUV brightenings (microflares) and even EUV waves. SDO Helioseismic and Magnetic Imager (HMI) observations show a ubiquitous presence of RNFs. Using HMI line-of-sight magnetograms on 2010 July 8, we find 388 RNFs in an area of 800 x 980 arcsec{sup 2} near the disk center where no active region is present. The sense of rotation shows a weak hemisphere preference. The unsigned magnetic flux of the RNFs is about 4.0 x 10{sup 21} Mx, or 78% of the total network flux. These observational phenomena at small scale reported in this Letter are consistent with those at large scale in active regions. The ubiquitous RNFs and EUV cyclones over the quiet Sun may suggest an effective way to heat the corona.

  9. Commission 12: Solar Radiation and Structure

    NASA Astrophysics Data System (ADS)

    Cauzzi, Gianna; Shchukina, Nataliya; Kosovichev, Alexander; Bianda, Michele; Brandenburg, Axel; Chou, Dean-Yi; Dasso, Sergio; Ding, Ming-De; Jefferies, Stuart; Krivova, Natalie; Kuznetsov, Vladimir D.; Moreno-Insertis, Fernando

    2016-04-01

    Commission 12 of the International Astronomical Union encompasses investigations of the internal structure and dynamics of the Sun, the quiet solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. The Commission sees participation of over 300 scientists worldwide.

  10. Contemplative Pedagogy: A Quiet Revolution in Higher Education

    ERIC Educational Resources Information Center

    Zajonc, Arthur

    2013-01-01

    During the last fifteen years a quiet pedagogical revolution has taken place in colleges, universities, and community colleges across the United States and increasingly around the world. Often flying under the name "contemplative pedagogy," it offers to its practitioners a wide range of educational methods that support the development of student…

  11. Design note about a 75 KVA quiet power distribution system

    SciTech Connect

    Visser, A.T.

    1984-04-05

    This note describes a 75KVA quiet power distribution system for X 653 in neutrino Lab D. It is fed from the regular AC distribution which exists in the building and it has no standby power. Its purpose is to remove electrical disturbances which are present on the regular AC distribution.

  12. On the hazard of quiet vehicles to pedestrians and drivers.

    PubMed

    Wogalter, Michael S; Lim, Raymond W; Nyeste, Patrick G

    2014-09-01

    The need to produce more efficient and less polluting vehicles has encouraged mass production of alternative energy vehicles, such as hybrid and electric cars. Many of these vehicles are capable of very quiet operation. While reducing noise pollution is desirable, quieter vehicles could negatively affect pedestrian safety because of reduced sound cues compared to louder internal combustion engines. Three studies were performed to investigate people's concern about this issue. In Study 1, a questionnaire completed by 378 people showed substantial positive interest in quiet hybrid and electric cars. However, they also indicated concern about the reduced auditory cues of quiet vehicles. In Study 2, 316 participants rated 14 sounds that could be potentially added to quiet alternative-energy vehicles. The data showed that participants did not want annoying sounds, but preferred adding "engine" and "hum" sounds relative to other types of sounds. In Study 3, 24 persons heard and rated 18 actual sounds within 6 categories that were added to a video of a hybrid vehicle driving by. The sounds most preferred were "engine" followed by "white noise" and "hum". Implications for adding sounds to facilitate pedestrians' detection of moving vehicles and for aiding drivers' awareness of speed are discussed. PMID:24035347

  13. Remote Observations of Ion Temperatures in the Quiet Time Magnetosphere

    NASA Technical Reports Server (NTRS)

    Keesee, A. M.; Buzulukova, N.; Goldstein, J.; McComas, D. J.; Scime, E. E.; Spence, H.; Fok, M. C.; Tallaksen, K.

    2011-01-01

    Ion temperature analysis of the first energetic neutral atom images of the quiet -time, extended magnetosphere provides evidence of multiple regions of ion heating. This study confirms the existence of a dawn -dusk asymmetry in ion temperature predicted for quiescent magnetospheric conditions by Spence and Kivelson (1993) and demonstrates that it is an inherent magnetospheric feature.

  14. The Reform Movement and the Quiet Crisis in Gifted Education.

    ERIC Educational Resources Information Center

    Renzulli, Joseph S.; Reis, Sally M.

    1991-01-01

    Gifted education faces a quiet crisis as reform movements focus on cosmetic administrative changes in school organization and management rather than interaction among teachers, students, and the material to be learned. Two goals of American education are presented: providing the best possible education to promising students and improving the…

  15. SLOW MAGNETOACOUSTIC WAVES OBSERVED ABOVE A QUIET-SUN REGION IN A DARK CAVITY

    SciTech Connect

    Liu Jiajia; Zhou Zhenjun; Wang Yuming; Liu Rui; Liao Chijian; Shen Chenglong; Zheng Huinan; Miao Bin; Su Zhenpeng; Wang, S.; Wang Bin E-mail: ymwang@ustc.edu.cn

    2012-10-20

    Waves play a crucial role in diagnosing the plasma properties of various structures in the solar corona and coronal heating. Slow magnetoacoustic (MA) waves are one of the important types of magnetohydrodynamic waves. In past decades, numerous slow MA waves were detected above active regions and coronal holes, but were rarely found elsewhere. Here, we investigate a 'tornado'-like structure consisting of quasi-periodic streaks within a dark cavity at about 40-110 Mm above a quiet-Sun region on 2011 September 25. Our analysis reveals that these streaks are actually slow MA wave trains. The properties of these wave trains, including phase speed, compression ratio, and kinetic energy density, are similar to those of the reported slow MA waves, except that the period of these waves is about 50 s, much shorter than the typical reported values (3-5 minutes).

  16. Ionospheric, protonospheric and total electron content in quiet geomagnetic conditions and during geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Nosikov, Igor; Klimenko, Maxim; Klimenko, Vladimir

    This report presents the results of studies the ionospheric, plasmaspheric and total electron content during recent minimum of solar activity in quiet geomagnetic condition and for geomagnetic storm on 26 September 2011. A comparison of the calculation results obtained using the GSM TIP model, with observational data of the mid- and high-latitude ionospheric sounding stations, as well as estimation of the plasmaspheric reservoir contribution into the total electron content obtained from GPS TEC measurements, COSMIC radio-occultation experiment and incoherent scatter radars were presented. The particular attention is given to the global distribution of the O+/H+ transition height in order to determine the top and low boundary for ionospheric and protonospheric electron content, respectively. This work was supported by Grant of Russian President №МК-4866.2014.5, №14-05-00578, and Program 22 RAS.

  17. The History of a Quiet-Sun Magnetic Element Revealed by IMaX/SUNRISE

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Bonet, José A.; Martínez Pillet, Valentín; Solanki, Sami K.; Schmidt, Wolfgang

    2014-07-01

    Isolated flux tubes are considered to be fundamental magnetic building blocks of the solar photosphere. Their formation is usually attributed to the concentration of magnetic field to kG strengths by the convective collapse mechanism. However, the small size of the magnetic elements in quiet-Sun areas has prevented this scenario from being studied in fully resolved structures. Here, we report on the formation and subsequent evolution of one such photospheric magnetic flux tube, observed in the quiet Sun with unprecedented spatial resolution (0.''15-0.''18) and high temporal cadence (33 s). The observations were acquired by the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne solar observatory. The equipartition field strength magnetic element is the result of the merging of several same polarity magnetic flux patches, including a footpoint of a previously emerged loop. The magnetic structure is then further intensified to kG field strengths by convective collapse. The fine structure found within the flux concentration reveals that the scenario is more complex than can be described by a thin flux tube model with bright points and downflow plumes being established near the edges of the kG magnetic feature. We also observe a daisy-like alignment of surrounding granules and a long-lived inflow toward the magnetic feature. After a subsequent weakening process, the field is again intensified to kG strengths. The area of the magnetic feature is seen to change in anti-phase with the field strength, while the brightness of the bright points and the speed of the downflows varies in phase. We also find a relation between the brightness of the bright point and the presence of upflows within it.

  18. The history of a quiet-sun magnetic element revealed by IMaX/SUNRISE

    SciTech Connect

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Bonet, José A.; Martínez Pillet, Valentín; Schmidt, Wolfgang

    2014-07-01

    Isolated flux tubes are considered to be fundamental magnetic building blocks of the solar photosphere. Their formation is usually attributed to the concentration of magnetic field to kG strengths by the convective collapse mechanism. However, the small size of the magnetic elements in quiet-Sun areas has prevented this scenario from being studied in fully resolved structures. Here, we report on the formation and subsequent evolution of one such photospheric magnetic flux tube, observed in the quiet Sun with unprecedented spatial resolution (0.''15-0.''18) and high temporal cadence (33 s). The observations were acquired by the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne solar observatory. The equipartition field strength magnetic element is the result of the merging of several same polarity magnetic flux patches, including a footpoint of a previously emerged loop. The magnetic structure is then further intensified to kG field strengths by convective collapse. The fine structure found within the flux concentration reveals that the scenario is more complex than can be described by a thin flux tube model with bright points and downflow plumes being established near the edges of the kG magnetic feature. We also observe a daisy-like alignment of surrounding granules and a long-lived inflow toward the magnetic feature. After a subsequent weakening process, the field is again intensified to kG strengths. The area of the magnetic feature is seen to change in anti-phase with the field strength, while the brightness of the bright points and the speed of the downflows varies in phase. We also find a relation between the brightness of the bright point and the presence of upflows within it.

  19. Numerical simulations of quiet sun magnetism: On the contribution from a small-scale dynamo

    SciTech Connect

    Rempel, M.

    2014-07-10

    We present a series of radiative MHD simulations addressing the origin and distribution of the mixed polarity magnetic field in the solar photosphere. To this end, we consider numerical simulations that cover the uppermost 2-6 Mm of the solar convection zone and we explore scales ranging from 2 km to 25 Mm. We study how the strength and distribution of the magnetic field in the photosphere and subsurface layers depend on resolution, domain size, and boundary conditions. We find that 50% of the magnetic energy at the τ = 1 level comes from fields with the less than 500 G strength and that 50% of the energy resides on scales smaller than about 100 km. While the probability distribution functions are essentially independent of resolution, properly describing the spectral energy distribution requires grid spacings of 8 km or smaller. The formation of flux concentrations in the photosphere exceeding 1 kG requires a mean vertical field strength greater than 30-40 G at τ = 1. The filling factor of kG flux concentrations increases with overall domain size as the magnetic field becomes organized by larger, longer-lived flow structures. A solution with a mean vertical field strength of around 85 G at τ = 1 requires a subsurface rms field strength increasing with depth at the same rate as the equipartition field strength. We consider this an upper limit for the quiet Sun field strength, which implies that most of the convection zone is magnetized close to the equipartition. We discuss these findings in view of recent high-resolution spectropolarimetric observations of quiet Sun magnetism.

  20. On the day-to-day variation of the equatorial electrojet during quiet periods

    NASA Astrophysics Data System (ADS)

    Yamazaki, Y.; Richmond, A. D.; Maute, A.; Liu, H.-L.; Pedatella, N.; Sassi, F.

    2014-08-01

    It has been known for a long time that the equatorial electrojet varies from day to day even when solar and geomagnetic activities are very low. The quiet time day-to-day variation is considered to be due to irregular variability of the neutral wind, but little is known about how variable winds drive the electrojet variability. We employ a numerical model introduced by Liu et al. (2013), which takes into account weather changes in the lower atmosphere and thus can reproduce ionospheric variability due to forcing from below. The simulation is run for May and June 2009. Constant solar and magnetospheric energy inputs are used so that day-to-day changes will arise only from lower atmospheric forcing. The simulated electrojet current shows day-to-day variability of ±25%, which produces day-to-day variations in ground level geomagnetic perturbations near the magnetic equator. The current system associated with the day-to-day variation of the equatorial electrojet is traced based on a covariance analysis. The current pattern reveals return flow at both sides of the electrojet, in agreement with those inferred from ground-based magnetometer data in previous studies. The day-to-day variation in the electrojet current is compared with those in the neutral wind at various altitudes, latitudes, and longitudes. It is found that the electrojet variability is dominated by the zonal wind at 100-120 km altitudes near the magnetic equator. These results suggest that the response of the zonal polarization electric field to variable zonal winds is the main source of the day-to-day variation of the equatorial electrojet during quiet periods.

  1. THE STORAGE AND DISSIPATION OF MAGNETIC ENERGY IN THE QUIET SUN CORONA DETERMINED FROM SDO/HMI MAGNETOGRAMS

    SciTech Connect

    Meyer, K. A.; Sabol, J.; Mackay, D. H.; Van Ballegooijen, A. A.

    2013-06-20

    In recent years, higher cadence, higher resolution observations have revealed the quiet-Sun photosphere to be complex and rapidly evolving. Since magnetic fields anchored in the photosphere extend up into the solar corona, it is expected that the small-scale coronal magnetic field exhibits similar complexity. For the first time, the quiet-Sun coronal magnetic field is continuously evolved through a series of non-potential, quasi-static equilibria, deduced from magnetograms observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, where the photospheric boundary condition which drives the coronal evolution exactly reproduces the observed magnetograms. The build-up, storage, and dissipation of magnetic energy within the simulations is studied. We find that the free magnetic energy built up and stored within the field is sufficient to explain small-scale, impulsive events such as nanoflares. On comparing with coronal images of the same region, the energy storage and dissipation visually reproduces many of the observed features. The results indicate that the complex small-scale magnetic evolution of a large number of magnetic features is a key element in explaining the nature of the solar corona.

  2. ON THE TEMPORAL EVOLUTION OF THE DISK COUNTERPART OF TYPE II SPICULES IN THE QUIET SUN

    SciTech Connect

    Sekse, D. H.; Rouppe van der Voort, L.; De Pontieu, B.

    2013-02-20

    The newly established type II spicule has been speculated to provide enough hot plasma to play an important role in the mass loading and heating of the solar corona. With the identification of rapid blueshifted excursions (RBEs) as the on-disk counterpart of type II spicules we have analyzed three different high-quality timeseries with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish Solar Telescope on La Palma and subjected to an automated detection routine to detect a large number of RBEs for statistical purposes. Our observations are of a quiet-Sun region at disk center and we find lower Doppler velocities, 15-40 km s{sup -1}, and Doppler widths, 2-15 km s{sup -1}, of RBEs than in earlier coronal hole studies, 30-50 km s{sup -1} and 7-23 km s{sup -1}, respectively. In addition, we examine the spatial dependence of Doppler velocities and widths along the RBE axis and conclude that there is no clear trend to this over the field of view or in individual RBEs in the quiet Sun at disk center. These differences with previous coronal hole studies are attributed to the more varying magnetic field configuration in quiet-Sun conditions. Using an extremely high-cadence data set has allowed us to improve greatly on the determination of lifetimes of RBEs, which we find to range from 5 to 60 s with an average lifetime of 30 s, as well as the transverse motions in RBEs, with transverse velocities up to 55 km s{sup -1} and averaging 12 km s{sup -1}. Furthermore, our measurements of the recurrence rates of RBEs provide important new constraints on coronal heating by spicules. We also see many examples of a sinusoidal wave pattern in the transverse motion of RBEs with periods averaging 54 s and amplitudes from 21.5 to 129 km which agrees well with previous studies of wave motion in spicules at the limb. We interpret the appearance of RBEs over their full length within a few seconds as the result of a combination of three kinds of motions as is earlier reported for

  3. Properties of magnetic elements in the quiet Sun using the marker-controlled watershed method

    NASA Astrophysics Data System (ADS)

    Xie, Z. X.; Yu, D. R.; Zhang, J.; Yang, S. H.; Hu, Q. H.

    2009-10-01

    Context: The quiet Sun is an important part of understanding the global magnetic properties of the Sun. A recently launched observation system, named HINODE, provides a lot of high-resolution images for studying the quiet Sun. Obviously, it is time-consuming to analyze these images by hand. It is desirable to develop a technique for recognizing magnetic elements, thus automatically computing magnetic properties and the relationship between magnetic elements and granulation. Aims: We design an automatic method of recognizing magnetic elements based on the features of HINODE magnetograms and of measuring their properties. Then we study the relationship between magnetic elements and granulation. Methods: We used the magnetogram, continuum image, and Dopplergram on April 16, 2007, which were taken with the Solar Optical Telescope instrument aboard HINODE. The field of view is 147.60 arcsec×162.30 arcsec in a quiet solar region, locating at disk center. We introduced the mark-controlled watershed method to detect magnetic elements automatically, because it is a popular image-segmentation method for dealing with overlapping objects. We took the centers that are the local maximum in all directions as the marks for restraining over-segmentation. We computed the properties of the detected magnetic elements and the relation among magnetic field strength, relative continuum intensity, and Doppler velocity at the same locations of magnetic elements. Results: We obtain the following results: (1) 34% of our observation region are covered by magnetic fields; (2) the magnetic flux distribution of all elements reaches a peak at 1.07× 1016 Mx for the whole region; (3) the relative continuum intensity distribution at the locations of magnetic elements reaches a peak at 0.97, which shows that the majority of magnetic elements located at the areas where the relative continuum intensity is less than its average. The relative continuum intensities in the areas with strong flux density

  4. Center-to-limb variation of the area covered by magnetic bright points in the quiet Sun

    NASA Astrophysics Data System (ADS)

    Bonet, J. A.; Cabello, I.; Sánchez Almeida, J.

    2012-03-01

    Context. The quiet Sun magnetic fields produce ubiquitous bright points (BPs) that cover a significant fraction of the solar surface. Their contribution to the total solar irradiance (TSI) is so-far unknown. Aims: We aim at measuring the center-to-limb variation (CLV) of the fraction of solar surface covered by quiet Sun magnetic bright points. The fraction is referred to as the fraction of covered surface (FCS). Methods: We count the area covered by BPs in G-band images obtained at various heliocentric angles with the 1-m Swedish Solar Telescope on La Palma. We restore the images to bring them close to the diffraction limit of the instrument (~0'.1). Results: The FCS is largest at the disk center (≃1%), and then drops down to become ≃0.2% at μ ≃ 0.3 (where μ is the cosine of the heliocentric angle). The relationship has a large scatter, which we evaluate by comparing different subfields within our FOVs. We develop a toy-model to describe the observed CLV, which considers the BPs as depressions in the mean solar photosphere characterized by a depth, a width, and a spread in the inclinations. Although the model is poorly constrained by observations, it shows the BPs to be shallow structures (depth < width) with a large range of inclinations. We also estimate how different parts of the solar disk may contribute to the TSI variations, finding that 90% is contributed by BPs with μ > 0.5, and half of it is due to BPs with μ > 0.8.

  5. The quiet Sun magnetism: What can we learn from the Hanle effect?

    NASA Astrophysics Data System (ADS)

    Faurobert, M.

    2012-12-01

    The physics of the outer layers of the Sun is mostly driven by magnetic phenomena. This is the reason why high resolution investigations of the magnetic fields in the hot and dilute outer atmosphere of the Sun, from the photosphere to the chromosphere and corona, are the major objectives of future large solar telescopes, such as the Advanced Technology Solar Telescope (ATST), or the European Solar Telescope (EST). The so-called "quiet Sun" is filled in with magnetic fields distributed in strengths and over a wide range of spatial scales. The magnetic energy content of this distribution of fields is a crucial issue, related to the long standing questions of the coronal and chromospheric heatings. Zeeman diagnostics of the magnetic fields depend crucially on the spatial resolution of the observations, whereas diagnostics based on the Hanle effect do provide valuable information on the average field strength even if the magnetic structures are not resolved. However, they rely on the precise radiative transfer modeling of polarized lines formed under non-LTE conditions. The use of the differential Hanle effect on lines with different magnetic sensitivities is a method of choice to obtain model-independent diagnostics. Another promissing way explored nowdays is to make use of the complementary diagnostics provided by both the Zeeman and Hanle effects when they can be observed in the same lines.

  6. The association of chromospheric and coronal phenomena with the evolution of the quiet sun magnetic fields

    NASA Technical Reports Server (NTRS)

    Harvey, Karen L.; Tang, Frances; Gaizauskas, Victor

    1986-01-01

    Using daily full-disk magnetograms and He I 10830 spectroheliograms to study the count and surface distribution of ephemeral regions over the solar cycle, Harvey (1985) concluded that the small dark structures seen in 10830, thought to correspond to X-ray bright points, were more often associated with magnetic bipoles that appeared to result from an encounter of already existing opposite polarity magentic flux than with emerging small magnetic bipoles (ephemeral regions). Such encounters would be more likely to occur in areas of mixed polarity. The fractional area of the sun covered by mixed polarity fields varies anti-correlated with the solar cycle leading to a possible explanation for the 180 degrees out of phase solar cycle variation of X-ray bright points. To establish the validity of this suggestion, a detailed study of time-sequence magnetic field, He I wavelength 10830, Ha, C IV, and Si II observations of selected areas of the quiet sun was initiated about 2 years ago. The preliminary results of this study are reported.

  7. The quiet Sun average Doppler shift of coronal lines up to 2 MK

    NASA Astrophysics Data System (ADS)

    Dadashi, N.; Teriaca, L.; Solanki, S. K.

    2011-10-01

    Context. The average Doppler shift shown by spectral lines formed from the chromosphere to the corona reveals important information on the mass and energy balance of the solar atmosphere, providing an important observational constraint to any models of the solar corona. Previous spectroscopic observations of vacuum ultra-violet (VUV) lines have revealed a persistent average wavelength shift of lines formed at temperatures up to 1 MK. At higher temperatures, the behaviour is still essentially unknown. Aims: Here we analyse combined SUMER (Solar Ultraviolet Measurements of Emitted Radiation)/SoHO (Solar and Heliospheric Observatory) and EIS (EUV Imaging Spectrometer)/Hinode observations of the quiet Sun around disk centre to determine, for the first time, the average Doppler shift of several spectral lines formed between 1 and 2 MK, where the largest part of the quiet coronal emission is formed. Methods: The measurements are based on a novel technique applied to EIS spectra to measure the difference in Doppler shift between lines formed at different temperatures. Simultaneous wavelength-calibrated SUMER spectra allow establishing the absolute value at the reference temperature of T ≈ 1 MK. Results: The average line shifts at 1 MK < T < 1.8 MK are modestly, but clearly bluer than those observed at 1 MK. By accepting an average blue shift of about (-1.8 ± 0.6) km s-1 at 1 MK (as provided by SUMER measurements), this translates into a maximum Doppler shift of (-4.4 ± 2.2) km s-1 around 1.8 MK. The measured value appears to decrease to about (-1.3 ± 2.6) km s-1 at the Fe xv formation temperature of 2.1 MK. Conclusions: The measured average Doppler shift between 0.01 and 2.1 MK, for which we provide a parametrisation, appears to be qualitatively and roughly quantitatively consistent with what foreseen by 3D coronal models where heating is produced by dissipation of currents induced by photospheric motions and by reconnection with emerging magnetic flux.

  8. Hierarchical analysis of the quiet-Sun magnetism

    NASA Astrophysics Data System (ADS)

    Asensio Ramos, A.; Martínez González, M. J.

    2014-12-01

    Standard statistical analysis of the magnetic properties of the quiet Sun rely on simple histograms of quantities inferred from maximum-likelihood estimations. Because of the inherent degeneracies, either intrinsic or induced by the noise, this approach is not optimal and can lead to highly biased results. We carried out a meta-analysis of the magnetism of the quiet Sun from Hinode observations using a hierarchical probabilistic method. This method allowed us to infer the statistical properties of the magnetic field vector over the observed field-of-view, consistently taking into account the uncertainties in each pixel that are due to noise and degeneracies. Our results imply that the magnetic fields are very weak, below 275 G with 95% probability, with a slight preference for horizontal fields, although the distribution is not far from a quasi-isotropic distribution.

  9. No evidence for radio-quiet BL Lacertae objects

    NASA Technical Reports Server (NTRS)

    Stocke, John T.; Morris, Simon L.; Gioia, Isabella; Maccacaro, Tommmaso; Schild, R. E.

    1990-01-01

    Using a large, flux-limited sample of faint X-ray sources, a search has been conducted for radio-quiet BL Lacertae objects. None has been found. Thirty-two X-ray-selected BL Lac objects and BL Lac candidates have been found within the sources of the Einstein Medium Sensitivity Survey (EMSS). Thirty-one of these have been observed with the VLA and all have been detected at 5 GHz. While the optical magnitudes of the EMSS BL Lac objects range from 17 to 20.8, their radio-to-optical spectral indices occupy a very small range. The very bright X-ray-selected BL Lac objects like PKS 2155-304 and Markarian 501 have similar range values. Therefore, unlike the clear dichotomy between radio-loud quasars and radio-quiet QSOs, there is no evidence for two populations of Lacertids distinguished by radio loudness.

  10. Quantitative Global Heat Transfer in a Mach-6 Quiet Tunnel

    NASA Technical Reports Server (NTRS)

    Sullivan, John P.; Schneider, Steven P.; Liu, Tianshu; Rubal, Justin; Ward, Chris; Dussling, Joseph; Rice, Cody; Foley, Ryan; Cai, Zeimin; Wang, Bo; Woodiga, Sudesh

    2012-01-01

    This project developed quantitative methods for obtaining heat transfer from temperature sensitive paint (TSP) measurements in the Mach-6 quiet tunnel at Purdue, which is a Ludwieg tube with a downstream valve, moderately-short flow duration and low levels of heat transfer. Previous difficulties with inferring heat transfer from TSP in the Mach-6 quiet tunnel were traced to (1) the large transient heat transfer that occurs during the unusually long tunnel startup and shutdown, (2) the non-uniform thickness of the insulating coating, (3) inconsistencies and imperfections in the painting process and (4) the low levels of heat transfer observed on slender models at typical stagnation temperatures near 430K. Repeated measurements were conducted on 7 degree-half-angle sharp circular cones at zero angle of attack in order to evaluate the techniques, isolate the problems and identify solutions. An attempt at developing a two-color TSP method is also summarized.

  11. Radio Quiet Protection at the Australian Square Kilometre array site

    NASA Astrophysics Data System (ADS)

    Harvey-Smith, Lisa

    2015-08-01

    Radio astronomy relies on the detection of very faint signals from the universe. Many radio telescopes are now detrimentally affected by radio frequency interference (RFI), which results from a wide range of active spectrum users such as communications, aviation and satellites. This is why many new radio observatories are being sited at increasingly remote locations.The site for the Square Kilometre Array and its pathfinders in Australia is the Murchison Radio-Astronomy Observatory (MRO). The MRO is located more than 350km from the nearest population centre and has a large radio-quiet zone that is managed under a range of legislative agreements.In this talk I will describe the radio quiet zone, what protection it gives, how it works and how astronomers interact with the spectrum management authorities.

  12. The influence of "quiet time" for patients in critical care.

    PubMed

    Maidl, Carolyn A; Leske, Jane S; Garcia, Annette E

    2014-10-01

    The primary aim was to examine the influence of "quiet time" in critical care. A dual-unit, nonrandomized, uncontrolled trial of a quiet time (QT) protocol was completed. A sample of adult patients from the Neurosciences Intensive Care Unit (NICU) and Cardiovascular Intensive Care Unit (CVICU) participated. Environmental stressors were reduced and patient rest promoted prior to QT. One hundred twenty-nine patients participated in 205 QTs. A one-way, repeated measure analysis of covariance (ANCOVA) was calculated comparing Richards-Campbell Sleep Questionnaire scores, pain and anxiety over three consecutive QTs. No significant statistical effect was found. However, patients rated sleep higher and anxiety levels decreased over consecutive QTs. Ninety-three percent of patients reported QT mattered to them. The combined efforts of nursing, medicine, and ancillary staff are necessary to foster periods of uninterrupted rest, thereby optimizing patient care. Further research is needed to determine if successive QTs positively influence patient outcomes. PMID:23847172

  13. Quiet Clean General Aviation Turbofan (QCGAT) technology study, volume 1

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The preliminary design of an engine which satisfies the requirements of a quiet, clean, general aviation turbofan (QCGAT) engine is described. Also an experimental program to demonstrate performance is suggested. The T700 QCGAT engine preliminary design indicates that it will radiate noise at the same level as an aircraft without engine noise, have exhaust emissions within the EPA 1981 Standards, have lower fuel consumption than is available in comparable size engines, and have sufficient life for five years between overhauls.

  14. Development and validation of 'quiet tail rotor' technology

    NASA Astrophysics Data System (ADS)

    Shenoy, Rajarama K.; Moffitt, Robert C.; Yoerkie, Charles M.; Childress, Otis, Jr.

    1991-05-01

    Systematic research leading to the development and validation of a 'quiet' full-scale tail rotor is described in this paper. Hover performance and acoustic test results acquired on the Sikorsky tail rotor whirl test facility, and some early results from the just-concluded flight tests are provided. The results show that substantial reduction in noise signature can be achieved simultaneously with improvements in performance when advances in aerodynamic and aeroacoustic technologies are judiciously applied.

  15. Dark Skies are a Universal Resource. So are Quiet Skies!

    NASA Astrophysics Data System (ADS)

    Maddalena, Ronald J.; Heatherly, S.

    2008-05-01

    You've just purchased your first telescope. But where to set it up? Certainly not a WalMart parking lot. Too much light pollution! In the same way that man-made light obscures our night sky and blinds ground-based optical telescopes, man-made radio signals blind radio telescopes as well. NRAO developed the Quiet Skies project to increase awareness of radio frequency interference (RFI) and radio astronomy in general by engaging students in local studies of RFI. To do that we created a sensitive detector which measures RFI. We produced 20 of these, and assembled kits containing detectors and supplementary materials for loan to schools. Students conduct experiments to measure the properties of RFI in their area, and input their measurements into a web-based data base. The Quiet Skies project is a perfect complement to the IYA Dark Skies Awareness initiative. We hope to place 500 Quiet Skies detectors into the field through outreach to museums and schools around the world. Should we be successful, we will sustain this global initiative via a continuing loan program. One day we hope to have a publicly generated image of the Earth which shows RFI much as the Earth at Night image illustrates light pollution. The poster will present the components of the project in detail, including our plans for IYA, and various low-cost alternative strategies for introducing RFI and radio astronomy to the public. We will share the results of some of the experiments already being performed by high school students. Development of the Quiet Skies project was funded by a NASA IDEAS grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  16. TF34 Quiet Nacelle nearfield acoustic test results

    NASA Technical Reports Server (NTRS)

    Coward, W. E.; Smith, E. B.; Sowers, H. D.

    1974-01-01

    The results of the nearfield acoustic tests conducted on the TF34 Quiet Nacelle are presented. The high fan noise suppression levels being sought (26 PNdB reduction in aft noise) necessitated the use of an extensive system of special nearfield acoustic instrumentation to properly evaluate the suppression achieved. The design, operation, and test results from each of these nearfield acoustic instrumentation systems are presented.

  17. Monitoring Radio Frequency Interference: The Quiet Skies Project

    NASA Astrophysics Data System (ADS)

    Rapp, S.; Gear, C.; Maddalena, R. J.; Heatherly, S. A.

    2004-12-01

    The Quiet Skies Project is a result of the Research Experience for Teacher (RET) program during the summer of 2004. Teachers were involved in discovering the relationship between radio frequency interference (RFI) and radio astronomy observations. S. Rapp participated in astronomy observations with the Green Bank Telescope in order to characterize RFI issues at radio observatories and worked closely with the Green Bank Interference Protection Group. This work included such tasks as mitigation of locally-generated RFI from power poles and running radiation propagation studies for transmitters within the National Radio Quiet Zone. A curriculum was created to allow high school students to participate in a research effort to determine RFI levels in their communities. The aim of the project is to promote student awareness of radio astronomy and radio frequency interference through an inquiry-based science curriculum. It is hoped that the project will go national by 2007. A prototype RFI detector was created and tested at four wavelengths; 850, 900, 1425, and 1675 MHz. High school students used a beta version of the RFI detector to explore the occurrence of RFI at their schools and in their communities. The student goals of the Quiet Skies Project are to: Measure interference levels at their schools and in their communities; Reduce and transmit their data to an NRAO data base; Use online spectrum allocation data, and local information to determine possible causes of interference in their area; Analyze the complex trade-offs between radio astronomy's need for quiet skies, and other commercial, and non-commercial uses of the spectrum and share their insights with others. This work was funded by the NSF-RET program and a grant from the NASA-IDEAS program

  18. Evidence for wave heating of the quiet-sun corona

    SciTech Connect

    Hahn, M.; Savin, D. W.

    2014-11-10

    We have measured the energy and dissipation of Alfvénic waves in the quiet Sun. A magnetic field model was used to infer the location and orientation of the magnetic field lines along which the waves are expected to travel. The waves were measured using spectral lines to infer the wave amplitude. The waves cause a non-thermal broadening of the spectral lines, which can be expressed as a non-thermal velocity v {sub nt}. By combining the spectroscopic measurements with this magnetic field model, we were able to trace the variation of v {sub nt} along the magnetic field. At each footpoint of the quiet-Sun loops, we find that waves inject an energy flux in the range of 1.3-5.5 × 10{sup 5} erg cm{sup –2} s{sup –1}. At the minimum of this range, this amounts to more than 80% of the energy needed to heat the quiet Sun. We also find that these waves are dissipated over a region centered on the top of the loops. The position along the loop where the damping begins is strongly correlated with the length of the loop, implying that the damping mechanism depends on the global loop properties rather than on local collisional dissipation.

  19. Intra-night Optical Variability in Radio Quiet Quasars

    NASA Astrophysics Data System (ADS)

    Wiita, P. J.; Gopal-Krishna; Sagar, R.

    1993-12-01

    We report results from a search for small-amplitude intra-night optical variability microvariability in 11 radio quiet, but optically bright and luminous, quasi-stellar objects. The observations were made using CCD's as N-star photometers on telescopes in Chile and India. The reduced data reveal indications of microvariability for several of the sources, but in no case has the reality of the fluctuations been clearly established. Observations of this type can discriminate among various theoretical mechanisms proposed for the origin of optical microvariability in AGNs. In particular, clear detections of microvariability in radio quiet QSOs would favor models where flares or other instabilities on accretion disks are responsible for the small fluctuations. On the other hand, statistically convincing evidence that such fluctuations are absent in radio quiet objects would support models based on shocks propagating down the relativistic jets which are only associated with radio loud AGN. Preliminary data for several sources have been published (Gopal-Krishna, Sagar & Wiita, 1993, MNRAS, 262, 963) and final results on the newer observations will be submitted soon (Gopal-Krishna et al. 1994). This work was supported in part by NSF grant AST9102106.

  20. Using SOHO to Understand CME-Producing Quiet-Region Filament Eruptions

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.; Harra, L. K.

    2006-01-01

    In recent years we have been studying solar eruptions in an attempt to determine their primary initiation mechanism. We have focused on events involving filaments, because motions of the filaments just prior to their violent eruption are indicative of changes in the entire magnetic field system involved in the eruption. When the pre-eruption filament resides in a quiet region, the motions leading up to eruption are slower than in similar eruptions in active regions due to the weaker magnetic field strength and correspondingly lower Alfven velocities. These early motions manifest themselves in a slow rise (a few km/s) of the filament, in some cases lasting several hours. After this the filament and associated magnetic structures erupt rapidly, accelerating to speeds of a few 10 kmh over a few minutes. Because of their slow evolution, quiet-region eruptions such as these can be effectively studied in EUV with SOHO/EIT, with its regular cadence of about 12 min. For several cases we have combined EIT images with SOHO/MDI magnetograms and data from other other instruments, and compared our observations with predictions from various eruption scenarios, in particular the "breakout" (Antiochos 1998), "tether cutting" (e.g., Moore et al. 2001), and MHD instability mechanisms. Here we present a representative example of a quiet-region eruption involving a filament ejection, that occurred on 2001 February 28 in a magnetically quadrupolar region and produced a halo CME in SOHO/LASCO images. In addition to EIT and MDI, we analyzed spectral data from SOHO/CDS and soft X-ray (SXR) images from Yohkoh/SXT. We found that flux emergence occurred near one end of the filament, and that both this emergence and resulting microflaring in SXRs and EUV were temporally and spatially closely related to the start of the filament's slow rise. Intensity changes (dimmings and brightenings) in the EIT and SXT images indicate that fields far removed from the erupting core were involved in the

  1. NASA gateways at L1 and L2 and the radio-quiet Moon Farside imperative

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2005-07-01

    NASA is currently studying the possibility of establishing future space bases at either of the libration points (also called Lagrangian points) L1 and L2 of the Earth Moon system. Two more similar points L1 and L2 of the Sun Earth system are also under consideration. Such possible future space bases are called Gateways in the NASA jargon. Each Gateway has its own pros and cons in terms of gravitational pull, distance from the Earth, and targets attainable by future spacecraft departing from the Gateway. A preliminary, concise review of these alternative possibilities is presented in this paper. We claim, however, that an extra factor has to be included in the NASA scenario also. This is the Radio-Quiet Moon Farside Imperative, called simply the Farside Imperative hereafter. This imperative is the need to keep at least the central part of the Farside of the Moon free from Radio Frequency Interference (RFI) coming from the Earth and shielded by the Moon's spherical body. In fact, the Farside of the Moon, and the Quiet Cone that extends into space above it for a few thousands of kilometers, represent a unique outpost for humankind: they are the only place close to the Earth where all radio-garbage produced by modern human civilization cannot reach. Thus, an array of radio antennas located there would sense the rest of the universe to an unprecedented degree of radio cleanliness, and, hence, of radio details. Not only would astrophysics and radio astronomy in general greatly benefit from this radio-quiet environment, but we would possibly achieve there for the first time a neat radio contact with an extraterrestrial civilization harboring somewhere else in the Galaxy (SETI) that could be too noisy to be detected on Earth. It is thus felt that a fair balance has to be reached between the astronautical drive to enlarge the exploration of the solar system and the imperative to keep the Farside of the Moon radio-clean. This paper puts forward a set of constructing

  2. Spatial deconvolution of spectropolarimetric data: an application to quiet Sun magnetic elements

    NASA Astrophysics Data System (ADS)

    Quintero Noda, C.; Asensio Ramos, A.; Orozco Suárez, D.; Ruiz Cobo, B.

    2015-07-01

    Context. One of the difficulties in extracting reliable information about the thermodynamical and magnetic properties of solar plasmas from spectropolarimetric observations is the presence of light dispersed inside the instruments, known as stray light. Aims: We aim to analyze quiet Sun observations after the spatial deconvolution of the data. We examine the validity of the deconvolution process with noisy data as we analyze the physical properties of quiet Sun magnetic elements. Methods: We used a regularization method that decouples the Stokes inversion from the deconvolution process, so that large maps can be quickly inverted without much additional computational burden. We applied the method on Hinode quiet Sun spectropolarimetric data. We examined the spatial and polarimetric properties of the deconvolved profiles, comparing them with the original data. After that, we inverted the Stokes profiles using the Stokes Inversion based on Response functions (SIR) code, which allow us to obtain the optical depth dependence of the atmospheric physical parameters. Results: The deconvolution process increases the contrast of continuum images and makes the magnetic structures sharper. The deconvolved Stokes I profiles reveal the presence of the Zeeman splitting while the Stokes V profiles significantly change their amplitude. The area and amplitude asymmetries of these profiles increase in absolute value after the deconvolution process. We inverted the original Stokes profiles from a magnetic element and found that the magnetic field intensity reproduces the overall behavior of theoretical magnetic flux tubes, that is, the magnetic field lines are vertical in the center of the structure and start to fan when we move far away from the center of the magnetic element. The magnetic field vector inferred from the deconvolved Stokes profiles also mimic a magnetic flux tube but in this case we found stronger field strengths and the gradients along the line-of-sight are larger

  3. Coronal extension of the MURaM radiative MHD code: From quiet sun to flare simulations

    NASA Astrophysics Data System (ADS)

    Rempel, Matthias D.; Cheung, Mark

    2016-05-01

    We present a new version of the MURaM radiative MHD code, which includes a treatment of the solar corona in terms of MHD, optically thin radiative loss and field-aligned heat conduction. In order to relax the severe time-step constraints imposed by large Alfven velocities and heat conduction we use a combination of semi-relativistic MHD with reduced speed of light ("Boris correction") and a hyperbolic formulation of heat conduction. We apply the numerical setup to 4 different setups including a mixed polarity quiet sun, an open flux region, an arcade solution and an active region setup and find all cases an amount of coronal heating sufficient to maintain a corona with temperatures from 1 MK (quiet sun) to 2 MK (active region, arcade). In all our setups the Poynting flux is self-consistently created by photospheric and sub-photospheric magneto-convection in the lower part of our simulation domain. Varying the maximum allowed Alfven velocity ("reduced speed of light") leads to only minor changes in the coronal structure as long as the limited Alfven velocity remains larger than the speed of sound and about 1.5-3 times larger than the peak advection velocity. We also found that varying details of the numerical diffusivities that govern the resistive and viscous energy dissipation do not strongly affect the overall coronal heating, but the ratio of resistive and viscous energy dependence is strongly dependent on the effective numerical magnetic Prandtl number. We use our active region setup in order to simulate a flare triggered by the emergence of a twisted flux rope into a pre-existing bipolar active region. Our simulation yields a series of flares, with the strongest one reaching GOES M1 class. The simulation reproduces many observed properties of eruptions such as flare ribbons, post flare loops and a sunquake.

  4. The Affect of the Thermosphere on Quiet-Time Plasmasphere Morphology

    NASA Astrophysics Data System (ADS)

    Krall, J.; Huba, J. D.

    2013-12-01

    The NRL SAMI3 ionosphere/plasmasphere code[1] has shown that the plasmasphere undergoes diurnal oscillations[2] and that those oscillations are consistent with variations found in in situ IMAGE/RPI density measurements during a quiet-time refilling event, 2001 February 1-5[3]. The SAMI3 ionosphere code includes 7 ion species (H+,He+,O+,N+,O+2,N+2,NO+), each treated as a separate fluid, with temperature equations being solved for H+, He+, O+ and e-. We include a Weimer potential at high latitudes, driven by the solar wind, and the self-consistent dynamo potential at mid-to-low latitudes, driven by specified winds, such as the HWM07 or HWM93 empirical model. During this quiet-time event, we find that the shape of the plasmasphere at any given time varies significantly with the wind model. In all cases, however, the diurnal oscillations persist and a similar degree of model-data agreement is found. [1] Huba, J. and J. Krall, 2013, "Modeling the plasmasphere with SAMI3," Geophys. Res. Lett. 40, 6-10, doi:10.1029/2012GL054300 [2] Krall, J., and J. D. Huba, 2013, "SAMI3 simulation of plasmasphere refilling," Geophys. Res. Lett., 40, 2484-2488, doi:10.1002/GRL.50458 [3] Krall, J, J. D. Huba, R. E. Denton and T.-W. Wu', 2013, "Density oscillations during post-storm plasmasphere refilling: 2001 February 1-5," Geophys. Res. Lett., submitted Research supported by NRL base funds and NASA.

  5. Micro Coronal Bright Points Observed in the Quiet Magnetic Network by SOHO/EIT

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.

    1997-01-01

    When one looks at SOHO/EIT Fe XII images of quiet regions, one can see the conventional coronal bright points (> 10 arcsec in diameter), but one will also notice many smaller faint enhancements in brightness (Figure 1). Do these micro coronal bright points belong to the same family as the conventional bright points? To investigate this question we compared SOHO/EIT Fe XII images with Kitt Peak magnetograms to determine whether the micro bright points are in the magnetic network and mark magnetic bipoles within the network. To identify the coronal bright points, we applied a picture frame filter to the Fe XII images; this brings out the Fe XII network and bright points (Figure 2) and allows us to study the bright points down to the resolution limit of the SOHO/EIT instrument. This picture frame filter is a square smoothing function (hlargelyalf a network cell wide) with a central square (quarter of a network cell wide) removed so that a bright point's intensity does not effect its own background. This smoothing function is applied to the full disk image. Then we divide the original image by the smoothed image to obtain our filtered image. A bright point is defined as any contiguous set of pixels (including diagonally) which have enhancements of 30% or more above the background; a micro bright point is any bright point 16 pixels or smaller in size. We then analyzed the bright points that were fully within quiet regions (0.6 x 0.6 solar radius) centered on disk center on six different days.

  6. General overview of the solar activity effects on the lower ionosphere

    NASA Technical Reports Server (NTRS)

    Danilov, A. D.

    1989-01-01

    Solar activity influences the ionospheric D region. That influence manifests itself both in the form of various solar induced disturbances and in the form of the D region dependence on solar activity parameters (UV-flux, interplanetary magnetic field, solar wind etc.) in quiet conditions. Relationship between solar activity and meteorological control of the D region behavior is considered in detail and examples of strong variations of aeronomical parameters due to solar or meteorological events are given.

  7. Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet-Sun region

    NASA Astrophysics Data System (ADS)

    Vargas Domínguez, S.; Palacios, J.; Balmaceda, L.; Cabello, I.; Domingo, V.

    2011-09-01

    High-resolution observations of a quiet-Sun internetwork region taken with the Solar 1-m Swedish Telescope in La Palma are analysed. We determine the location of small-scale vortex motions in the solar photospheric region by computing the horizontal proper motions of small-scale structures on time-series of images. These plasma convectively driven swirl motions are associated to (1) downdrafts (that have been commonly explained as corresponding to sites where the plasma is cooled down and hence returned to the interior below the visible photospheric level) and (2) horizontal velocity vectors converging on a central point. The sink cores are proved to be the final destination of passive floats tracing plasma flows towards the centre of each vortex. We establish the occurrence of these events to be 1.4 × 10-3 and 1.6 × 10-3 vortices Mm-2 min-1, respectively, for the two time-series analysed here.

  8. Centre-to-limb properties of small, photospheric quiet-Sun jets

    NASA Astrophysics Data System (ADS)

    Rubio da Costa, F.; Solanki, S. K.; Danilovic, S.; Hizberger, J.; Martínez-Pillet, V.

    2015-02-01

    Context. Strongly Doppler-shifted Stokes V profiles have been detected in the quiet Sun with the IMaX instrument on-board the SUNRISE stratospheric balloon-borne telescope. High velocities are required to produce such signals, hence these events have been interpreted as jets, although other sources are also possible. Aims: We aim to characterize the variation of the main properties of these events (occurrence rate, lifetime, size, and velocities) with their position on the solar disk between disk centre and the solar limb. Methods: These events were identified in SUNRISE/IMaX data according to the same objective criteria at all available positions on the solar disk. Their properties were determined using standard techniques. Results: Our study yielded a number of new insights into this phenomenon. Most importantly, the number density of these events is independent of the heliocentric angle, meaning that the investigated supersonic flows are nearly isotropically distributed. Size and lifetime are also nearly independent of the heliocentric angle, while their intensity contrast increases towards the solar limb. The Stokes V jets are associated with upflow velocities deduced from Stokes I, which are stronger towards the limb. Their intensity decreases with time, while their line-of-sight velocity does not display a clear temporal evolution. Their association with linear polarization signals decreases towards the limb. Conclusions: The density of events appears to be independent of heliocentric angle, establishing that they are directed nearly randomly. If these events are jets triggered by magnetic reconnection between emerging magnetic flux and the ambient field, then our results suggest that there is no preferred geometry for the reconnection process.

  9. Outflow Structure of the Quiet Sun Corona Probed by Spacecraft Radio Scintillations in Strong Scattering

    NASA Astrophysics Data System (ADS)

    Imamura, Takeshi; Tokumaru, Munetoshi; Isobe, Hiroaki; Shiota, Daikou; Ando, Hiroki; Miyamoto, Mayu; Toda, Tomoaki; Häusler, Bernd; Pätzold, Martin; Nabatov, Alexander; Asai, Ayumi; Yaji, Kentaro; Yamada, Manabu; Nakamura, Masato

    2014-06-01

    Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area. The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.

  10. Outflow structure of the quiet sun corona probed by spacecraft radio scintillations in strong scattering

    SciTech Connect

    Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato; Tokumaru, Munetoshi; Shiota, Daikou; Isobe, Hiroaki; Asai, Ayumi; Miyamoto, Mayu; Häusler, Bernd; Pätzold, Martin; Nabatov, Alexander; Yaji, Kentaro; Yamada, Manabu

    2014-06-20

    Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area. The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.

  11. Orbiting solar observatory 8 high resolution ultraviolet spectrometer experiment

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Oscillations, physical properties of the solar atmosphere, motions in the quiet solar atmosphere, coronal holes, motions in solar active regions, solar flares, the structure of plage regions, an atlas, and aeronomy are summarized. Photometric sensitivity, scattered light, ghosts, focus and spectral resolution, wavelength drive, photometric sensitivity, and scattered light, are also summarized. Experiments are described according to spacecraft made and experiment type. Some of the most useful data reduction programs are described.

  12. Characteristics of the Solar Wind in the Vicinity of Jupiter and its Impact on the Jovian Magnetopause Location

    NASA Astrophysics Data System (ADS)

    Joy, S. P.; Kivelson, M. G.; Mafi, J.; Mafi, R. J.; Khurana, K. K.; Russell, C. T.

    2001-12-01

    We have previously reported that the jovian magnetopause location is described by a bimodal probability density function (Joy et al., 2000). Here we present our analysis of the solar wind characteristics in the vicinity of Jupiter that give rise to the observed bimodal distribution. Hourly samples of solar wind and IMF parameters, within 0.25 AU of Jupiter, obtained from the Coordinated Heliospheric Observations (COHO) database are analyzed and their statistical distributions are discussed. Data are separated into disturbed (CIR) regions, quiet regions (between CIRs), and by solar cycle phase. For many parameters (B, density, dynamic pressure, Mach number) the disturbed and quiet solar winds have clearly distinct and separate statistical distributions. The IMF strength varies by a factor of 4-5 between quiet and disturbed regions but varies by less than 20% over the solar cycle. The difference between the mean dynamic pressures in the disturbed versus the quiet solar winds at solar minimum is more than twice the difference observed at solar maximum. Plasma beta at solar minimum is nearly double the values observed during solar maximum while disturbed and quiet regions are within 20% of each other. And finally, the fraction of the solar rotation that is disturbed increases from 33% at solar minimum to 45% at solar maximum. This last result may describe the most significant component of the solar cycle variation with respect to its potential impact on the jovian system boundary locations. With the exception of plasma beta, the differences between the quiet and the disturbed solar wind (factors of 2-5) are more substantial than the differences between solar minimum and maximum (20-50%).

  13. Ethernet-Based DAQ System for QUIET-II Detectors

    NASA Astrophysics Data System (ADS)

    Nagai, M.; Ishidoshiro, K.; Higuchi, T.; Ikeno, M.; Hasegawa, M.; Hazumi, M.; Tajima, O.; Tanaka, M.; Uchida, T.

    2012-06-01

    The B-modes in cosmic microwave background polarization are a smoking gun for the inflationary universe. For the detection of the B-modes, having a large detector array is a generic approach since the B-modes is so faint pattern ( T b≲0.1 μK). The Q/U Imaging ExperimenT Phase-II (QUIET-II) is proposed to search the B-modes, using an array with 500 HEMT-based polarimeters. Each polarimeter element has 4-outputs, therefore we have to manage 2000 channels in total. We developed a scalable DAQ system based on TCP/Ethernet for QUIET-II. The DAQ system is composed of the polarimeters, ADC boards, a Master Clock and a control computer (PC). The analog signals from the polarimeters are digitized on the ADC boards. On-board demodulation, which synchronizes the phase flip modulations on the polarimeter, extracts the polarized components in the digitized signal. The Master Clock distributes all necessary clocks to the ADC boards as well as the polarimeters. This scheme guarantees the synchronization of the modulations and demodulations. We employed Ethernet-based communication scheme between the data collection program (Collector) on the PC and the ADC boards as well as the Master Clock. Such an Ethernet-based communication scheme allows us to construct a simple structure of the upper level software, which results in the high scalability to increase the number of channels. All basic functions and requirements are confirmed by the laboratory tests; demonstration with test signals as well as the signals from the polarimeters, measurements of the data transfer rate, and the synchronous operation with two ADC boards. Therefore, the DAQ system is confirmed to be suitable for QUIET-II.

  14. Moon Farside, Quiet Cone and the "RLI" Experiment

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    The Farside of the Moon is a unique place. Radio emissions coming from the Earth, and notably the from Telecommunication Satellites orbiting the Earth, don't get there since shielded by the Moon's spherical body. A radio telescope placed inside Crater Daedalus (just at the center of the Farside) would thus sense no man-made RFI (Radio Frequency Interference) and would be ideal for all radio astronomical and SETI searches. Above the Farside, a conical region extends into space, the ``Quiet Cone'', tangent to the Moon surface and with apex a few thousands of kilometers above the Moon. The size of the Quiet Cone, however, is only vaguely known, and changes in time, because the orbits of secret military satellites around the Earth are of course unknown. The only way to know the current, actual size of the Quiet Cone is to send a radiometer into orbit around the Moon and find out where the RFI coming from the Earth is actually shielded and where it is not. The RLI Experiment (RLI is an acronym for ``Radiometro Lunare Italiano'', i.e. Italian Moon Radiometer), is currently under construction by an Italian team coordinated by this author as Principal Investigator. The RLI is hopefully going to be put into orbit around the Moon before 2007. This will be done by placing the RLI radiometer aboard the ``Trailbalzer'', the first American commercial Moon spacecraft, built by TransOrbital Inc.. The RLI Experiment will take direct measurements of the intensity of man-made RFI around two frequencies: The band in between 10.7 and 11.8 GHz (main frequency band of European TV transmissions and, in part, also of American TV transmissions) and The band in between 10 Hz and 10 kHz, to get a Fourier spectrum of the very thin Moon atmosphere. A scientific and technical description of the RLI mission is given in this paper.

  15. Clamoring for quiet: new ways to mitigate noise.

    PubMed

    Manuel, John

    2005-01-01

    New technologies are providing innovative ways to reduce sound levels in many areas. Aircraft engineers are finding ways to reduce the noise produced by jet engines, while road builders are using rubber-enhanced pavement to quiet highway noise. Indoor acoustics are benefiting from materials that transform sound waves to heat, and so-called active noise control reduces harmful sounds through production of a mirror-image sound field. And new lawn equipment makes weekends at home quieter for yard lovers and their neighbors. PMID:15631960

  16. NASA/GE quiet engine C acoustic test results

    NASA Technical Reports Server (NTRS)

    Kazin, S. B.; Pass, J. E.

    1974-01-01

    The acoustic investigation and evaluation of the C propulsion turbofan engine are discussed. The engine was built as a part of the Quiet Engine Program. The objectives of the program are as follows: (1) to determine the noise levels produced turbofan bypass engines, (2) to demonstrate the technology and innovations which will reduce the production and radiation of noise in turbofan engines, and (3) to acquire experimental acoustic and aerodynamic data for high bypass turbofan engines to provide a better understanding of noise production mechanisms. The goals of the program called for a turbofan engine 15 to 20 PNdB quieter than currently available engines in the same thrust class.

  17. Structure of magnetic fields on the quiet sun

    NASA Technical Reports Server (NTRS)

    Wang, Haimin

    1988-01-01

    To obtain quantitative temporal and spatial information on the network magnetic fields, auto- and cross-correlation techniques are applied to the Big Bear videomagnetogram data. The average size of the network magnetic elements derived from the auto-correlation curve is about 5700 km. The distance between the primary and secondary peak in the auto-correlation curve is about 17,000 km, which is half of the size of the supergranule as determined from the velocity map. The canceling features and the emergence of ephemeral regions are the major sources for the loss and replenishment of magnetic flux on the quiet sun.

  18. The microwave brightness temperature spectrum of the quiet sun

    NASA Technical Reports Server (NTRS)

    Zirin, H.; Baumert, B. M.; Hurford, G. J.

    1991-01-01

    New measurements of the microwave brightness temperature spectrum of the center of the quiet sun, acquired at Owens Valley over several months during the 1986-1987 sunspot minimum, are reported. The resulting brightness temperature spectra are consistent with previous data, but exhibit much less frequency-to-frequency scatter. The corona is fitted well by an optically thin source at temperature of 10 to the 6th k, scale height H = 5 x 10 to the 9th, and density of 3.2 x 10 to the 8th/cu cm, and the chromosphere, an optically thick source at around 11,000 k.

  19. Design Guidelines for Quiet Fans and Pumps for Space Vehicles

    NASA Technical Reports Server (NTRS)

    Lovell, John S.; Magliozzi, Bernard

    2008-01-01

    This document presents guidelines for the design of quiet fans and pumps of the class used on space vehicles. A simple procedure is presented for the prediction of fan noise over the meaningful frequency spectrum. A section also presents general design criteria for axial flow fans, squirrel cage fans, centrifugal fans, and centrifugal pumps. The basis for this report is an experimental program conducted by Hamilton Standard under NASA Contract NAS 9-12457. The derivations of the noise predicting methods used in this document are explained in Hamilton Standard Report SVHSER 6183, "Fan and Pump Noise Control," dated May 1973 (6).

  20. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    Conceptual designs of Quiet Turbofan STOL Short-Haul Transport Aircraft for the mid-1980 time period are developed and analyzed to determine their technical, operational, and economic feasibility. A matrix of aircraft using various high-lift systems and design parameters are considered. Variations in aircraft characteristics, airport geometry and location, and operational techniques are analyzed systematically to determine their effects on the market, operating economics, and community acceptance. In these studies, the total systems approach is considered to be critically important in analyzing the potential of STOL aircraft to reduce noise pollution and alleviate the increasing air corridor and airport congestion.

  1. Fantastic Ca2+ "z-waves" fade out quietly.

    PubMed

    Hallett, Maurice B; Lebiedz, Dirk; Mommer, Mario S; Reble, Carina; Saltmarsh, Esther J

    2009-07-01

    The first report that high speed Ca(2+) waves travel in a restricted zone around the cell periphery in a clockwise manner and which can only be revealed by very high speed imaging has been quietly retracted. In the original report, a single small region of high Ca(2+) was seen to spin around the cell periphery and around phagosomes formed within phagocytes in a manner unlike anything reported previously. This consequently caused a lot of interest. Several other papers reporting a similar phenomenon in a variety of cells were also published by the same lab and the phenomenon has been included in high profile reviews such as in Science. However, several groups have failed to reproduce this work and attempts to detect the Ca(2+) waves or the mechanism for their generation have failed. Now, the original report has been quietly retracted. In this short commentary, we give a brief account of the sorry story of the non-existent circulating Ca(2+) waves (z-waves) in the hope that the literature can be rectified and that future cell calcium biologists are not misled by these fantastic and spurious Ca(2+) reports. PMID:19450875

  2. Empirical modeling of the quiet time nightside magnetosphere

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.; Spence, H. E.; Stern, D. P.

    1993-01-01

    Empirical modeling of plasma pressure and magnetic field for the quiet time nightside magnetosphere is investigated. Two models are constructed for this study. One model, referred to here as T89R, is basically the magnetic field model of Tsyganenko (1989) but is modified by the addition of an inner eastward ring current at a radial distance of approximately 3 RE as suggested by observation. The other is a combination of the T89R model and the long version of the magnetic field model of Tsyganenko (1987) such that the former dominates the magnetic field in the inner magnetosphere while the latter prevails in the distant tail. The distribution of plasma pressure which is required to balance the magnetic force for each of these two field models is computed along the tail axis in the midnight meridian. The occurrence of pressure anisotropy in the inner magnetospheric region is also taken into account by determining an empirical fit to the observed plasma pressure anisotropy. This represents the first effort to obtain the plasma pressure distribution in force equilibrium with magnetic stresses from an empirical field model with the inclusion of pressure anisotropy. The inclusion of pressure anisotropy alters the plasma pressure by as much as a factor of approximately 3 in the inner magnetosphere. The deduced plasma pressure profile along the tail axis is found to be in good agreement with the observed quiet time plasma pressure for geocentric distances between approximately 2 and approximately 35 RE.

  3. Dark energy and the quietness of the local Hubble flow

    NASA Astrophysics Data System (ADS)

    Axenides, M.; Perivolaropoulos, L.

    2002-06-01

    The linearity and quietness of the local (<10 Mpc) Hubble flow (LHF) in view of the very clumpy local universe is a long standing puzzle in standard and in open CDM (cold dark matter) cosmogony. The question addressed in this paper is whether the antigravity component of the recently discovered dark energy can cool the velocity flow enough to provide a solution to this puzzle. We calculate the growth of matter fluctuations in a flat universe containing a fraction ΩX(t0) of dark energy obeying the time independent equation of state pX=wρX. We find that dark energy can indeed cool the LHF. However the dark energy parameter values required to make the predicted velocity dispersion consistent with the observed value vrms~=40 km/s have been ruled out by other observational tests constraining the dark energy parameters w and ΩX. Therefore despite the claims of recent qualitative studies, dark energy with time independent equation of state cannot by itself explain the quietness and linearity of the local Hubble flow.

  4. Empirical modeling of the quiet time nightside magnetosphere

    SciTech Connect

    Lui, A.T.Y. ); Spence, H.E. ); Stern, D.P. )

    1994-01-01

    Empirical modeling of plasma pressure and magnetic field for the quiet time nightside magnetosphere is investigated. Two models are constructed for this study. One model, referred to here as T89R, is basically the magnetic field model of Tsyganenko but is modified by the addition of an inner eastward ring current at a radial distance of [approximately]3 R[sub E] as suggested by observation. The other is a combination of the T89R model and the long version of the magnetic field model of Tsyganenko such that the former dominates the magnetic field in the inner magnetosphere, whereas the latter prevails in the distant tail. The distribution of plasma pressure, which is required to balance the magnetic force for each of these two field models, is computed along the tail axis in the midnight meridian. The occurrence of pressure anisotropy in the inner magnetospheric region is also taken into account by determining an empirical fit to the observed plasma pressure anisotropy. This effort is the first attempt to obtain the plasma pressure distribution in force equilibrium with magnetic stresses from an empirical field model with the inclusion of pressure anisotropy. The inclusion of pressure anisotropy alters the plasma pressure by as much as a factor of [approximately]3 in the inner magnetosphere. The deduced plasma pressure profile along the tail axis is found to be in good agreement with the observed quiet time plasma pressure for geocentric distances between [approximately]2 and [approximately]35 R[sub E]. 40 refs., 5 figs.

  5. Empirical modeling of the quiet time nightside magnetosphere

    SciTech Connect

    Lui, A.T.Y.; Spence, H.E.; Stern, D.P.

    1993-12-31

    Empirical modeling of plasma pressure and magnetic field for the quiet time nightside magnetosphere is investigated. Two models are constructed for this study. One model, referred to here as T89R, is basically the magnetic field model of Tsyganenko but is modified by the addition of an inner eastward ring current at a radial distance of approximately 3 RE as suggested by observation. The other is a combination of the T89R model and the long version of the magnetic field model of Tsyganenko such that the former dominates the magnetic field in the inner magnetosphere while the latter prevails in the distant tail. The distribution of plasma pressure which is required to balance the magnetic force for each of these two field models is computed along the tail axis in the midnight meridian. The occurrence of pressure anisotropy in the inner magnetospheric region is also taken into account by determining an empirical fit to the observed plasma pressure anisotropy. This represents the first effort to obtain the plasma pressure distribution in force equilibrium with magnetic stresses from an empirical field model with the inclusion of pressure anisotropy. The inclusion of pressure anisotropy alters the plasma pressure by as much as a factor of approximately 3 in the inner magnetosphere. The deduced plasma pressure profile along the tail axis is found to be in good agreement with the observed quiet time plasma pressure for geocentric distances between approximately 2 and approximately 35 RE.

  6. Structure of magnetic fields on the quiet sun

    NASA Astrophysics Data System (ADS)

    Wang, Haimin

    To obtain quantitative temporal and spatial information on the network magnetic fields, the author applied auto- and cross-correlation techniques to the Big Bear videomagnetogram data. The average size of the network magnetic elements derived from the auto-correlation curve is about 5700 km. The distance between the primary and secondary peak in the auto-correlation curve is about 17000 km, which is half of the size of the supergranule as determined from the velocity map. The correlation time is about 10 to 20 hours. The diffusion constant derived from the cross-correlation curve is 150 km2s-1. In the quiet regions the total magnetic flux in a window 3arcmin×4arcmin changes very little in nearly 10 hours. That means the emergence and the disappearance of magnetic flux are in balance. The cancelling features and the emergence of ephemeral regions are the major sources for the loss and replenishment of magnetic flux on the quiet Sun.

  7. Photospheric Magnetic Field Properties of Flaring vs. Flare-Quiet Active Regions I: Data, General Approach, and Statistical Results

    NASA Astrophysics Data System (ADS)

    Leka, K. D.; Barnes, G.

    2003-05-01

    Photospheric vector magnetic field data from the U. Hawai`i Imaging Vector Magnetograph are examined for pre-event signatures unique to solar energetic phenomena. Parameters are constructed from B(x,y) to describe (for example) the distributions of the field, spatial gradients of the field, vertical current, current helicity, ''twist'' parameter α and magnetic shear angles. A quantitative statistical approach employing discriminant analysis and Hotelling's T2-test is applied to the magnitude and temporal evolution of parameters from 24 flare-event and flare-quiet epochs from seven active regions. We demonstrate that (1) when requiring a flare-unique signature, numerous candidate parameters are nullified by considering flare-quiet epochs, (2) a more robust method exists for estimating error rates than conventional ''truth tables'', (3) flaring and flare-quiet populations do not necessarily have low error rates for classification even when statistically distinguishable, and that (4) simultaneous consideration of a large number of variables is required to produce acceptable error rates. That is, when the parameters are considered individually, they show little ability to differentiate between the two populations; multi-variable combinations can discriminate the populations and/or result in perfect classification tables. In lieu of constructing a single all-variable discriminant function to quantify the flare-predictive power of the parameters considered, we devise a method whereby all permutations of the four-variable discriminant functions are ranked by Hotelling's T2. We present those parameters (e.g. the temporal increase of the kurtosis of the spatial distribution of the vertical current density) which consistently appear in the best combinations, indicating that they may play an important role in defining a pre-event photospheric state. While no single combination is clearly the best discriminator, we demonstrate here the requisite approach: include flare-quiet

  8. Effect of Repeated Exposures on Word Learning in Quiet and Noise

    ERIC Educational Resources Information Center

    Blaiser, Kristina M.; Nelson, Peggy B.; Kohnert, Kathryn

    2015-01-01

    This study examines the impact of repeated exposures on word learning of preschool children with and without hearing loss (HL) in quiet and noise conditions. Participants were 19 children with HL and 17 peers with normal hearing (NH). Children were introduced to 16 words: 8 in quiet and 8 in noise conditions. Production and identification scores…

  9. Quiet. Indian Ethnic Heritage Studies Curriculum Development Project 1974-75.

    ERIC Educational Resources Information Center

    Bublitz, Mona

    Part of the Native American way is to be quiet; traditionally Native Americans had to be quiet to survive, to be secure, and to show respect. This curriculum guide, suitable for use at intermediate grade levels, presents a unit designed to share this important aspect of the Native American culture. The six lessons provide teachers with background…

  10. Why Some Fast and Wide Coronal Mass Ejections are Radio-quiet?

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Xie, H.; Aguilar-Rodriguez, E.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L.

    2007-05-01

    The radio-quiet CMEs lack type II radio burst association in the metric and decameter-hectometric (DH) wavelengths. We compiled CMEs faster than 900 km/s and wider than 60 degrees and checked against metric and interplanetary type II bursts and found that about one third of them were radio-quiet. We compared the radio-quiet CMEs with the radio-loud ones occurring over the same study period (1996-2005). The radio-quiet and radio-loud CMEs had average speeds of 1129 and 1524 km/s, respectively bracketing the average speed of all FW CMEs (1303 km/s). The width distributions also showed a similar behavior: the fraction of halo and partial halo CMEs was the largest for the radio-loud CMEs (54%), smallest for the radio-quiet CMEs (18%) and intermediate for all fast and wide CMEs (42%). The majority of radio-quiet CMEs (55%) were back-sided; most of the frontsided ones also originated close to the limb. This is in contrast to the radio-loud CMEs which originated generally on the disk with only a small fraction (13%) was back-sided. The average flare size was also slightly smaller for the radio-quiet CMEs compared to that of radio-loud CMEs. Back-sided and limb CMEs have only part of the shock surface visible to the observer. This seems to be an important factor deciding whether a CME is radio quiet.

  11. Quiet Spike Build-Up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    NASA's Dryden Flight Research Center uses a modified F-15B (836) aircraft as a testbed for a variety of flight research:experiments mounted underneath the aircraft fuselage. The F-15B was selected to fly Gulfstream Aerospace Corporation's (GAC)QuietSpike(TM)(QS) project; however, this experiment is very unique and unlike any of the previous testbed experiments flown on the F-15B. It involves the addition of a relatively long quiet spike boom attached to the radar bulkhead of the aircraft. This QS experiment is a stepping stone to airframe structural morphing technologies designed to mitigate sonic born strength of business jets over land. The QS boom is a concept in Which an aircraft's front-end would be extended prior to supersonic acceleration. This morphing would effectively lengthen the aircraft, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. Prior to flying the Quietspike(TM) experiment on the F-15B aircraft several ground vibration tests (GVT) were required in order to understand the QS modal characteristics and coupling effects with the F-15B. However, due to the project's late hardware delivery of the QS and the intense schedule, a "traditional" GVT of the mated F-1513 Quietspike(tm) ready-for-flight configuration would not have left sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. The objective of the QuietSpike (TM) build-up ground testing approach was to ultimately obtain confidence in the F-15B Quietspike(TM) finite element model (FEM) to be used for the flutter analysis. In order to obtain the F15B QS FEM with reliable foundation stiffness between the QS and the F-15B radar bulkhead as well as QS modal characteristics, several different GVT configurations were performed. EAch of the four GVT's performed had a

  12. Dynamics of Multi-cored Magnetic Structures in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Martínez Pillet, Valentín; Solanki, Sami K.; Schmidt, Wolfgang

    2015-09-01

    We report on the dynamical interaction of quiet-Sun magnetic fields and granular convection in the solar photosphere as seen by Sunrise. We use high spatial resolution (0.″15–0.″18) and temporal cadence (33 s) spectropolarimetric Imaging Magnetograph eXperiment data, together with simultaneous CN and Ca ii H filtergrams from Sunrise Filter Imager. We apply the SIR inversion code to the polarimetric data in order to infer the line of sight velocity and vector magnetic field in the photosphere. The analysis reveals bundles of individual flux tubes evolving as a single entity during the entire 23 minute data set. The group shares a common canopy in the upper photospheric layers, while the individual tubes continually intensify, fragment and merge in the same way that chains of bright points in photometric observations have been reported to do. The evolution of the tube cores are driven by the local granular convection flows. They intensify when they are “compressed” by surrounding granules and split when they are “squeezed” between two moving granules. The resulting fragments are usually later regrouped in intergranular lanes by the granular flows. The continual intensification, fragmentation and coalescence of flux results in magnetic field oscillations of the global entity. From the observations we conclude that the magnetic field oscillations first reported by Martínez González et al. correspond to the forcing by granular motions and not to characteristic oscillatory modes of thin flux tubes.

  13. Moon-based EUV imaging of the Earth's plasmasphere and image reconstruction during quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxin; Wang, Huaning; He, Fei; Chen, Bo

    An extreme ultraviolet (EUV) camera was mounted on the top of the instrumental module of the Chinese Chang'E-3 (CE-3) lunar lander which has landed on lunar surface on December 14, 2013. On December 21, 2013, the EUV camera was powered on and the global plasmaspheric 30.4 nm emission was imaged from the Moon for the first time on December 25, 2013 after tests of the camera. Clear plasmasphere region, plasmapause, Earth’s shadow can be seen in the images. During this period, the geomagnetic activity is extremely quiet, so the plasmasphere is diffusive and no plume structure was observed. By application of the reconstruction algorithm of He et al. [2011] to the images, the equatorial plasmapause positions and plasmasphere density distributions were reconstructed. The reconstructed plasmapause positions are in consistent with in situ observations by THEMIS and DMSP satellites. In future, more plasmaspheric images under different solar wind, interplanetary magnetic field and geomagnetic conditions will be detected, and then the plasmaspheric dynamics and its role on inner magnetospheric coupling will be investigated.

  14. Dynamic Flaring Non-potential Fields on Quiet Sun Network Scales

    NASA Astrophysics Data System (ADS)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.

    2016-05-01

    We report on the identification of dynamic flaring non-potential structures on quiet Sun (QS) supergranular network scales. Data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory allow for the high spatial and temporal resolution of this diverse class of compact structures. The rapidly evolving non-potential events presented here, with lifetimes <10 minutes, are on the order of 10″ in length. Thus, they contrast significantly with well-known active region (AR) non-potential structures such as high-temperature X-ray and EUV sigmoids (>100″) and micro-sigmoids (>10″) with lifetimes on the order of hours to days. The photospheric magnetic field environment derived from the Helioseismic and Magnetic Imager shows a lack of evidence for these flaring non-potential fields being associated with significant concentrations of bipolar magnetic elements. Of much interest to our events is the possibility of establishing them as precursor signatures of eruptive dynamics, similar to notions for AR sigmoids and micro-sigmoids, but associated with uneventful magnetic network regions. We suggest that the mixed network flux of QS-like magnetic environments, though unresolved, can provide sufficient free magnetic energy for flaring non-potential plasma structuring. The appearance of non-potential magnetic fields could be a fundamental process leading to self-organized criticality in the QS-like supergranular network and contribute to coronal heating, as these events undergo rapid helicial and vortical relaxations.

  15. Ultraviolet continuum absorption /less than about 1000 A/ above the quiet sun transition region

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Feldman, U.

    1982-01-01

    Lyman continuum absorption shortward of 912 A in the quiet sun solar transition region is investigated by combining spectra obtained from the Apollo Telescope Mount experiments on Skylab. The most recent atomic data are used to compute line intensities for lines that fall on both sides of the Lyman limit. Lines of O III, O IV, O V, and S IV are considered. The computed intensity ratios of most lines from O IV, O V, and S IV agree with the experimental ratios to within a factor of 2. However, the discrepancies show no apparent wavelength dependence. From this fact, it is concluded that at least part of the discrepancy between theory and observation for lines of these ions can be accounted for by uncertainties in instrumental calibration and atomic data. However, difficulties remain in reconciling observation and theory, particularly for lines of O III, and one line of S IV. The other recent results of Schmahl and Orrall (1979) are also discussed in terms of newer atomic data.

  16. The Quiet Sun Network at Subarcsecond Resolution: VAULT Observations and Radiative Transfer Modeling of Cool Loops

    NASA Astrophysics Data System (ADS)

    Patsourakos, S.; Gouttebroze, P.; Vourlidas, A.

    2007-08-01

    One of the most enigmatic regions of the solar atmosphere is the transition region (TR), corresponding to plasmas with temperatures intermediate of the cool, few thousand K, chromosphere and the hot, few million K, corona. The traditional view is that the TR emission originates from a thin thermal interface in hot coronal structures, connecting their chromosphere with their corona. This paradigm fails badly for cool plasmas (~T<105 K), since it predicts emission orders of magnitude less than what it is observed. It was therefore proposed that the ``missing'' TR emission could originate from tiny, isolated from the hot corona, cool loops at TR temperatures. A major problem in investigating this proposal is the very small sizes of the hypothesized cool loops. Here, we report the first spatially resolved observations of subarcsecond-scale looplike structures seen in the Lyα line made by the Very High Angular Resolution Ultraviolet Telescope (VAULT). The subarcsecond (~0.3") resolution of VAULT allows us to directly view and resolve looplike structures in the quiet Sun network. We compare the observed intensities of these structures with simplified radiative transfer models of cool loops. The reasonable agreement between the models and the observations indicates that an explanation of the observed fine structure in terms of cool loops is plausible.

  17. Harmonic quiet-day curves as magnetometer baselines for ionospheric current analyses

    NASA Astrophysics Data System (ADS)

    van de Kamp, M.

    2013-03-01

    This paper presents a novel method to determine a baseline for magnetometer data. This baseline consists of all magnetic field components not related to ionospheric and magnetospheric disturbances, i.e. all field components due to solar quiet variations and other background variations, as well as equipment effects. Extraction of this baseline is useful when the disturbance magnetic field is analysed. The full baseline is composed of two main constituents: the diurnal baseline and the long-term baseline. For the diurnal baseline, first "templates" are derived, based on the lowest few harmonics of the daily curves from the quietest days. The diurnal variation of the baseline is obtained by interpolating between these templates. This method ensures a smooth baseline at all times, avoiding any discontinuities at transitions between days. The long-term baseline is obtained by interpolating between the daily median values. This way, the baseline is ensured to follow long-term trends, such as seasonal and tidal variations, as well as equipment drift. The daily median values are calculated for all days except the most disturbed ones; a procedure is included to ensure that the median values used are unaffected by disturbances. This procedure avoids many problems associated with other existing baseline procedures, and makes magnetometer data suitable, for instance, for the calculation of ionospheric equivalent currents related to geomagnetic storms. Even data from remote unmanned magnetometers, which exhibit significant equipment effects, can be made suitable this way, which can give valuable contributions to the equivalent current database.

  18. Dynamics of Multi-cored Magnetic Structures in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.; Martínez Pillet, Valentín; Solanki, Sami K.; Schmidt, Wolfgang

    2015-09-01

    We report on the dynamical interaction of quiet-Sun magnetic fields and granular convection in the solar photosphere as seen by Sunrise. We use high spatial resolution (0.″15-0.″18) and temporal cadence (33 s) spectropolarimetric Imaging Magnetograph eXperiment data, together with simultaneous CN and Ca ii H filtergrams from Sunrise Filter Imager. We apply the SIR inversion code to the polarimetric data in order to infer the line of sight velocity and vector magnetic field in the photosphere. The analysis reveals bundles of individual flux tubes evolving as a single entity during the entire 23 minute data set. The group shares a common canopy in the upper photospheric layers, while the individual tubes continually intensify, fragment and merge in the same way that chains of bright points in photometric observations have been reported to do. The evolution of the tube cores are driven by the local granular convection flows. They intensify when they are “compressed” by surrounding granules and split when they are “squeezed” between two moving granules. The resulting fragments are usually later regrouped in intergranular lanes by the granular flows. The continual intensification, fragmentation and coalescence of flux results in magnetic field oscillations of the global entity. From the observations we conclude that the magnetic field oscillations first reported by Martínez González et al. correspond to the forcing by granular motions and not to characteristic oscillatory modes of thin flux tubes.

  19. DETERMINING THE MAGNETIZATION OF THE QUIET SUN PHOTOSPHERE FROM THE HANLE EFFECT AND SURFACE DYNAMO SIMULATIONS

    SciTech Connect

    Shchukina, Nataliya; Trujillo Bueno, Javier E-mail: jtb@iac.es

    2011-04-10

    The bulk of the quiet solar photosphere is thought to be significantly magnetized, due to the ubiquitous presence of a tangled magnetic field at subresolution scales with an average strength (B) {approx} 100 G. This conclusion was reached through detailed three-dimensional (3D) radiative transfer modeling of the Hanle effect in the Sr I 4607 A line, using the microturbulent field approximation and assuming that the shape of the probability density function of the magnetic field strength is exponential. Here, we relax both approximations by modeling the observed scattering polarization in terms of the Hanle effect produced by the magnetic field of a 3D photospheric model resulting from a (state-of-the-art) magneto-convection simulation with surface dynamo action. We show that the scattering polarization amplitudes observed in the Sr I 4607 A line can be explained only after enhancing the magnetic strength of the photospheric model by a sizable scaling factor, F {approx} 10, which implies (B) {approx} 130 G in the upper photosphere. We also argue that in order to explain both the Hanle depolarization of the Sr I 4607 A line and the Zeeman signals observed in Fe I lines, we need to introduce a height-dependent scaling factor, such that the ensuing (B) {approx} 160 G in the low photosphere and (B) {approx} 130 G in the upper photosphere.

  20. Avco Lycoming quiet clean general aviation turbofan engine

    NASA Technical Reports Server (NTRS)

    Wilson, C. A.

    1980-01-01

    A fan module was developed using an existing turboshaft engine. The fan was designed using the latest in large engine noise control technology. A mixer was added to reduce the already low exhaust gas velocity. A nacelle incorporating sound treatment was provided for the test engine. A noise prediction model was used through the design process to evaluate the various design alternatives. Acoustic tests were then made to verify the prediction and identify the noise characteristics of the fan, core, jet, and sound treatment. Analysis of the recorded data yielded close agreement with the expected results. Core noise, as was expected, was the predominant source of noise for the quiet clean general aviation turbofan (QCGAT) engine. Flyover noise predictions were made which indicated that the Avco Lycoming QCGAT engine would meet the goals set for the QCGAT program.

  1. No quiet surrender: molecular guardians in multiple sclerosis brain

    PubMed Central

    Steinman, Lawrence

    2015-01-01

    The brain under immunological attack does not surrender quietly. Investigation of brain lesions in multiple sclerosis (MS) reveals a coordinated molecular response involving various proteins and small molecules ranging from heat shock proteins to small lipids, neurotransmitters, and even gases, which provide protection and foster repair. Reduction of inflammation serves as a necessary prerequisite for effective recovery and regeneration. Remarkably, many lesion-resident molecules activate pathways leading to both suppression of inflammation and promotion of repair mechanisms. These guardian molecules and their corresponding physiologic pathways could potentially be exploited to silence inflammation and repair the injured and degenerating brain and spinal cord in both relapsing-remitting and progressive forms of MS and may be beneficial in other neurologic and psychiatric conditions. PMID:25831441

  2. Electrical noise to a knee joint stabilizes quiet bipedal stance.

    PubMed

    Kimura, Tetsuya; Kouzaki, Motoki

    2013-04-01

    Studies have shown that a minute, noise-like electrical stimulation (ES) of a lower limb joint stabilizes one-legged standing (OS), possibly due to the noise-enhanced joint proprioception. To demonstrate the practical utility of this finding, we assessed whether the bipedal stance (BS), relatively stable and generally employed in daily activities, is also stabilized by the same ES method. Twelve volunteers maintained quiet BS with or without an unperceivable, noise-like ES of a knee joint. The results showed that the average amplitude, peak-to-peak amplitude, and standard deviation of the foot center of pressure in the anteroposterior direction were significantly attenuated by the ES (P<0.05). These results indicate that the BS also can be stabilized by an unperceivable, noise-like ES of a knee joint. PMID:23044409

  3. Io's Sodium Clouds: a Quiet Spring of 2005

    NASA Astrophysics Data System (ADS)

    Wilson, J.; Mendillo, M.; Baumgardner, J.

    2005-08-01

    Observations of Io's sodium clouds from February to June 2005 indicate that Io was in the ``quiet" state atmospheric escape, as postulated by Mendillo et al. (2004). This is the first year of a 3-year project to monitor Io's sodium clouds (which are indicative of atmospheric loss from Io) and sulfur ions in the plasma torus (representative of the magnetospheric heavy ion source) with groundbased images. Our goal is to compare variability in the clouds and torus with observations of Io's volcanic infrared ``hot spots" (e.g., Marchis et al. 2005) in order to track the flow of mass from Io's volcanoes into Jupiter's magnetosphere. This research is funded in part by NASA's Planetary Astronomy Program. Marchis et al., Keck AO survey of Io global volcanic activity between 2 and 5 microns, Icarus, 176, 96-122, 2005. Mendillo et al., Io's volcanic control of Jupiter's extended neutral clouds, Icarus, 170, 430-442, 2004.

  4. Quiet High Speed Fan II (QHSF II): Final Report

    NASA Technical Reports Server (NTRS)

    Kontos, Karen; Weir, Don; Ross, Dave

    2012-01-01

    This report details the aerodynamic, mechanical, structural design and fabrication of a Honey Engines Quiet High Speed Fan II (lower hub/tip ratio and higher specific flow than the Baseline I fan). This fan/nacelle system incorporates features such as advanced forward sweep and an advanced integrated fan/fan exit guide vane design that provides for the following characteristics: (1) Reduced noise at supersonic tip speeds, in comparison to current state-of-the-art fan technology; (2) Improved aeroelastic stability within the anticipated operating envelope; and (3) Aerodynamic performance consistent with current state-of-the-art fan technology. This fan was fabricated by Honeywell and tested in the NASA Glenn 9- by 15-Ft Low Speed Wind Tunnel for aerodynamic, aeromechanical, and acoustic performance.

  5. Airesearch QCGAT program. [quiet clean general aviation turbofan engines

    NASA Technical Reports Server (NTRS)

    Heldenbrand, R. W.; Norgren, W. M.

    1979-01-01

    A model TFE731-1 engine was used as a baseline for the NASA quiet clean general aviation turbofan engine and engine/nacelle program designed to demonstrate the applicability of large turbofan engine technology to small general aviation turbofan engines, and to obtain significant reductions in noise and pollutant emissions while reducing or maintaining fuel consumption levels. All new technology design for rotating parts and all items in the engine and nacelle that contributed to the acoustic and pollution characteristics of the engine system were of flight design, weight, and construction. The major noise, emissions, and performance goals were met. Noise levels estimated for the three FAR Part 36 conditions, are 10 t0 15 ENPdB below FAA requirements; emission values are considerably reduced below that of current technology engines; and the engine performance represents a TSFC improvement of approximately 9 percent over other turbofan engines.

  6. No quiet surrender: molecular guardians in multiple sclerosis brain.

    PubMed

    Steinman, Lawrence

    2015-04-01

    The brain under immunological attack does not surrender quietly. Investigation of brain lesions in multiple sclerosis (MS) reveals a coordinated molecular response involving various proteins and small molecules ranging from heat shock proteins to small lipids, neurotransmitters, and even gases, which provide protection and foster repair. Reduction of inflammation serves as a necessary prerequisite for effective recovery and regeneration. Remarkably, many lesion-resident molecules activate pathways leading to both suppression of inflammation and promotion of repair mechanisms. These guardian molecules and their corresponding physiologic pathways could potentially be exploited to silence inflammation and repair the injured and degenerating brain and spinal cord in both relapsing-remitting and progressive forms of MS and may be beneficial in other neurologic and psychiatric conditions. PMID:25831441

  7. Experimental quiet engine program aerodynamic performance of Fan C

    NASA Technical Reports Server (NTRS)

    Giffin, R. G.; Parker, D. E.; Dunbar, L. W.

    1972-01-01

    This report presents the aerodynamic component test results of Fan C, a high-bypass-ratio, low-aerodynamic-loading, 1550 feet per second (472.4 m/sec), single-stage fan, which was designed and tested as part of the NASA Experimental Quiet Engine Program. The fan was designed to deliver a bypass pressure ratio of 1.60 with an adiabatic efficiency of 84.2 percent at a total fan flow of 915 lb/sec (415.0 kg/sec). It was tested with and without inlet distortion. A bypass total-pressure ratio of 1.61 and an adiabatic efficiency of 83.9 percent at a total fan flow of 921 lb/sec (417.8 kg/sec) were actually achieved. An operating margin in excess of 14.6 percent was demonstrated at design speed.

  8. Statistical analysis of quiet stance sway in 2-D

    PubMed Central

    DiZio, Paul; Lackner, James R.

    2014-01-01

    Subjects exposed to a rotating environment that perturbs their postural sway show adaptive changes in their voluntary spatially directed postural motion to restore accurate movement paths but do not exhibit any obvious learning during passive stance. We have found, however, that a variable known to characterize the degree of stochasticity in quiet stance can also reveal subtle learning phenomena in passive stance. We extended Chow and Collins (Phys Rev E 52(1):909–912, 1995) one-dimensional pinned-polymer model (PPM) to two dimensions (2-D) and then evaluated the model’s ability to make analytical predictions for 2-D quiet stance. To test the model, we tracked center of mass and centers of foot pressures, and compared and contrasted stance sway for the anterior–posterior versus medio-lateral directions before, during, and after exposure to rotation at 10 rpm. Sway of the body during rotation generated Coriolis forces that acted perpendicular to the direction of sway. We found significant adaptive changes for three characteristic features of the mean square displacement (MSD) function: the exponent of the power law defined at short time scales, the proportionality constant of the power law, and the saturation plateau value defined at longer time scales. The exponent of the power law of MSD at a short time scale lies within the bounds predicted by the 2-D PPM. The change in MSD during exposure to rotation also had a power-law exponent in the range predicted by the theoretical model. We discuss the Coriolis force paradigm for studying postural and movement control and the applicability of the PPM model in 2-D for studying postural adaptation. PMID:24477760

  9. Statistical analysis of quiet stance sway in 2-D.

    PubMed

    Bakshi, Avijit; DiZio, Paul; Lackner, James R

    2014-04-01

    Subjects exposed to a rotating environment that perturbs their postural sway show adaptive changes in their voluntary spatially directed postural motion to restore accurate movement paths but do not exhibit any obvious learning during passive stance. We have found, however, that a variable known to characterize the degree of stochasticity in quiet stance can also reveal subtle learning phenomena in passive stance. We extended Chow and Collins (Phys Rev E 52(1):909-912, 1995) one-dimensional pinned-polymer model (PPM) to two dimensions (2-D) and then evaluated the model's ability to make analytical predictions for 2-D quiet stance. To test the model, we tracked center of mass and centers of foot pressures, and compared and contrasted stance sway for the anterior-posterior versus medio-lateral directions before, during, and after exposure to rotation at 10 rpm. Sway of the body during rotation generated Coriolis forces that acted perpendicular to the direction of sway. We found significant adaptive changes for three characteristic features of the mean square displacement (MSD) function: the exponent of the power law defined at short time scales, the proportionality constant of the power law, and the saturation plateau value defined at longer time scales. The exponent of the power law of MSD at a short time scale lies within the bounds predicted by the 2-D PPM. The change in MSD during exposure to rotation also had a power-law exponent in the range predicted by the theoretical model. We discuss the Coriolis force paradigm for studying postural and movement control and the applicability of the PPM model in 2-D for studying postural adaptation. PMID:24477760

  10. Microflaring in Low-Lying Core Fields and Extended Coronal Heating in the Quiet Sun

    NASA Technical Reports Server (NTRS)

    Porter, Jason G.; Falconer, D. A.; Moore, Ronald L.

    1999-01-01

    We have previously reported analyses of Yohkoh SXT data examining the relationship between the heating of extended coronal loops (both within and stemming from active regions) and microflaring in core fields lying along neutral lines near their footpoints (J. G. Porter, D. A. Falconer, and R. L. Moore 1998, in Solar Jets and Coronal Plumes, ed. T. Guyenne, ESA SP-421, and references therein). We found a surprisingly poor correlation of intensity variations in the extended loops with individual microflares in the compact heated areas at their feet, despite considerable circumstancial evidence linking the heating processes in these regions. Now, a study of Fe XII image sequences from SOHO EIT show that similar associations of core field structures with the footpoints of very extended coronal features can be found in the quiet Sun. The morphology is consistent with the finding of Wang et al. (1997, ApJ 484, L75) that polar plumes are rooted at sites of mixed polarity in the magnetic network. We find that the upstairs/downstairs intensity variations often follow the trend, identified in the active region observations, of a weak correspondence. Apparently much of the coronal heating in the extended loops is driven by a type of core field magnetic activity that is "cooler" than the events having the coronal signature of microflares, i.e., activity that results in little heating within the core fields themselves. This work was funded by the Solar Physics Branch of NASA's Office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

  11. Interpretation of Dynamics Explorer far UV images of the quiet time thermosphere

    NASA Technical Reports Server (NTRS)

    Meier, R. R.; Cox, R.; Strickland, D. J.; Craven, J. D.; Frank, L. A.

    1995-01-01

    A selected set of far ultra violet images of Earth have been analyzed quanitatively to establish their validity for studying thermospheric weather. The set of images chosen for the study was restricted to mostly geomagnetically quiet conditions in order to obtain a baseline understanding of the relationship between the observations and thermospheric phenomenology. The images included low to modrerate solar activity levels. A new model was developed to generate global dayglow images using first principles methods. The mass Spectrometer/incoherent scatter (MSIS-86) model was used to predict the thermospheric concentrations. The analyses of thermospheric images observed in the 123 to 160-nm nominal passband show that the spectral composition for observations on the projected earth disk is dominated by O I 130.4-nm radiation (85-90%), with concentrations from O I 135.6-nm and N2 Lyman-Birge-Hopefield (LBH) bands of about 5-8% each. The synthetic images reproduce the global features of the observed images rather well. Differences between the model and the data are attributed to real atmospheric effects, such as atomic oxygen depletions which are not well reproduced by the MSIS model when geomagnetic activity is elevated. The absoute values recorded were 38-54% higher than predicted. We attribute this discrepancy to low values of the solar extreme ultraviolet irradiances used in the model. Images obtained in the 136 to 165-nm nominal passband are a factor of 2.7 greater than the model. The excess signal observed is most likely due to a long wavelength tail in the instrument sensitivity which allowed Rayleigh scattered sunlight between 180and 250nm to be detected. The understanding of the Dynamics Explorer (DE 1) images gained by this study provides the basis for future work on the global response of the theremosphere to geomagnetic forcing.

  12. STEREO ICMEs and their Solar Source Regions Near Solar Minimum

    NASA Astrophysics Data System (ADS)

    Toy, V.; Li, Y.; Luhmann, J. G.; Schroeder, P.; Vourlidas, A.; Jian, L. K.; Russell, C. T.; Galvin, A. B.; Simunac, K.; Acuna, M.; Sauvaud, J. A.; Skoug, R.; Petrie, G.

    2008-12-01

    Although the quiet activity period surrounding the current solar minimum has prevailed since the launch of STEREO in October 2006, there have been at least 9 clear in-situ detections of ICMEs (Interplanetary Coronal Mass Ejections) by one or more spacecraft during the time the imagers were also operating. These observations provide unusually complete data sets for evaluating helio-longitude extent of the ICMEs and for identifying the probable solar cause(s) of the events. In this poster we present information on these ICMEs from the IMPACT and PLASTIC and ACE in-situ investigations, together with solar images from STEREO and SOHO that seem to capture the causative activity at the Sun. We find that even though the Sun was very quiet in '07-'08, with few active regions visible in GONG and SOHO magnetograms, there were numerous CME candidates that erupted through the near-equatorial helmet streamers. Most events could be identified with EUV disk activity as well as a coronagraph CME, even if the associated active region was very small or weak. Old cycle active regions, new and decayed, continued to maintain a warp in the large-scale helmet streamer belt that was a frequent site of the eruptions. However, the warp in the streamer belt may simply indicate that the active region(s) present is(are) sufficiently strong to affect the large scale quiet coronal field structure. Overall we see no gross differences between the solar activity and ICME causes during this and the previous solar activity minimum, when the Streamer belt was less warped due to the existence of stronger solar polar fields.

  13. Differential emission measure analysis of active region cores and quiet Sun for the non-Maxwellian κ-distributions

    NASA Astrophysics Data System (ADS)

    Mackovjak, Š.; Dzifčáková, E.; Dudík, J.

    2014-04-01

    Context. The non-Maxwellian κ-distributions have been detected in the solar wind and can explain intensities of some transition region lines. Presence of such distributions in the outer layers of the solar atmosphere influences the ionization and excitation equilibrium and widens the line contribution functions. This behavior may be reflected on the reconstructed differential emission measure (DEM). Aims: We aim to investigate the influence of κ-distributions on the reconstructed DEMs. Methods: We perform DEM reconstruction for three active region cores and a quiet Sun region using the Withbroe-Sylwester method and the regularization method. Results: We find that the reconstructed DEMs depend on the value of κ. The DEMs of the active region cores show similar behavior with decreasing κ, or an increasing departure from the Maxwellian distribution. For lower κ, the peaks of the DEMs are typically shifted to higher temperatures and the DEMs themselves become more concave. This is caused by the less steep high-temperature slopes for lower κ. However, the low-temperature slopes do not change significantly even for extremely low κ. The behavior of the quiet-Sun DEM distribution is different. It becomes progressively less multithermal for lower κ with the EM-loci plots that indicate near-isothermal plasma for κ = 2. Conclusions: The κ-distributions can influence the reconstructed DEMs. The slopes of the DEM, however, do not change with κ significantly enough to produce different constraints on the heating mechanism in terms of frequency of coronal heating events.

  14. A broad look at solar physics adapted from the solar physics study of August 1975

    NASA Technical Reports Server (NTRS)

    Parker, E.; Timothy, A.; Beckers, J.; Hundhausen, A.; Kundu, M. R.; Leith, C. E.; Lin, R.; Linsky, J.; Macdonald, F. B.; Noyes, R.

    1979-01-01

    The current status of our knowledge of the basic mechanisms involved in fundamental solar phenomena is reviewed. These include mechanisms responsible for heating the corona, the generation of the solar wind, the particle acceleration in flares, and the dissipation of magnetic energy in field reversal regions, known as current sheets. The discussion covers solar flares and high-energy phenomena, solar active regions; solar interior, convection, and activity; the structure and energetics of the quiet solar atmosphere; the structure of the corona; the solar composition; and solar terrestrial interactions. It also covers a program of solar research, including the special observational requirements for spectral and angular resolution, sensitivity, time resolution, and duration of the techniques employed.

  15. Variation of solar acoustic emission and its relation to phase of the solar cycle

    NASA Astrophysics Data System (ADS)

    Chen, Ruizhu; Zhao, Junwei

    2016-05-01

    Solar acoustic emission is closely related to solar convection and photospheric magnetic field. Variation of acoustic emission and its relation to the phase of solar cycles are important to understand dynamics of solar cycles and excitation of acoustic waves. In this work we use 6 years of SDO/HMI Dopplergram data to study acoustic emissions of the whole sun and of the quiet-sun regions, respectively, in multiple acoustic frequency bands. We show the variation of acoustic emission from May 2010 to April 2016, covering half of the solar cycle 24, and analyze its correlation with the solar activity level indexed by daily sunspot number and total magnetic flux. Results show that the correlation between the whole-Sun acoustic emission and the solar activity level is strongly negative for low frequencies between 2.5 and 4.5 mHz, but strongly positive for high frequencies between 4.5 and 6.0 mHz. For high frequencies, the acoustic emission excess in sunspot halos overwhelms the emission deficiency in sunspot umbrae and penumbrae. The correlation between the acoustic emission in quiet regions and the solar activity level is negative for 2.5-4.0 mHz and positive for 4.0-5.5 mHz. This shows that the solar background acoustic power, with active regions excluded, also varies during a solar cycle, implying the excitation frequencies or depths are highly related to the solar magnetic field.

  16. Focused Study on the Quiet Side Effect in Dwellings Highly Exposed to Road Traffic Noise

    PubMed Central

    Renterghem, Timothy Van; Botteldooren, Dick

    2012-01-01

    This study provides additional evidence for the positive effect of the presence of a quiet façade at a dwelling and aims at unraveling potential mechanisms. Locations with dominant road traffic noise and high Lden-levels at the most exposed façade were selected. Dwellings both with and without a quiet façade were deliberately sought out. Face-to-face questionnaires (N = 100) were taken to study the influence of the presence of a quiet side in relation to noise annoyance and sleep disturbance. As a direct effect, the absence of a quiet façade in the dwelling (approached as a front-back façade noise level difference smaller than 10 dBA) leads to an important increase of at least moderately annoyed people (odds-ratio adjusted for noise sensitivity equals 3.3). In an indirect way, a bedroom located at the quiet side leads to an even stronger reduction of the self-reported noise annoyance (odds-ratio equal to 10.6 when adjusted for noise sensitivity and front façade Lden). The quiet side effect seems to be especially applicable for noise sensitive persons. A bedroom located at the quiet side also reduces noise-induced sleep disturbances. On a loud side, bedroom windows are more often closed, however, conflicting with the preference of dwellers. PMID:23330222

  17. The polarized Galaxy at 43 and 95 GHz as seen by QUIET

    NASA Astrophysics Data System (ADS)

    Melvær Ruud, Tone

    2015-08-01

    I will present mm-wave polarization measurements of two Galactic plane fields, one of which cover the Galactic Centre, made by the QUIET instrument from October 2008 through December 2010. QUIET was a ground-based radiometer experiment targeting the polarized CMB in two frequency bands, Q (43 GHz) and W (95 GHz). Recognizing the importance of constraining the foregrounds in order to produce clean CMB maps, we also devoted some 1400 hours to observing the Galactic plane. The resulting QUIET maps represent the deepest Galactic polarization measurements to date at their frequencies, with instrumental noise levels 2-6 times lower than corresponding maps from Planck and WMAP, and very low systematics. The WMAP and QUIET sky maps at 43 GHz agree very well, while Planck shows systematic deviations from both QUIET and WMAP, with a signature resembling residual temperature-to-polarization leakage at the 0.2% level. Both raw QUIET and inverse variance weighted QUIET+WMAP maps are made publicly available.

  18. Do Quiet Areas Afford Greater Health-Related Quality of Life than Noisy Areas?

    PubMed Central

    Shepherd, Daniel; Welch, David; Dirks, Kim N.; McBride, David

    2013-01-01

    People typically choose to live in quiet areas in order to safeguard their health and wellbeing. However, the benefits of living in quiet areas are relatively understudied compared to the burdens associated with living in noisy areas. Additionally, research is increasingly focusing on the relationship between the human response to noise and measures of health and wellbeing, complementing traditional dose-response approaches, and further elucidating the impact of noise and health by incorporating human factors as mediators and moderators. To further explore the benefits of living in quiet areas, we compared the results of health-related quality of life (HRQOL) questionnaire datasets collected from households in localities differentiated by their soundscapes and population density: noisy city, quiet city, quiet rural, and noisy rural. The dose-response relationships between noise annoyance and HRQOL measures indicated an inverse relationship between the two. Additionally, quiet areas were found to have higher mean HRQOL domain scores than noisy areas. This research further supports the protection of quiet locales and ongoing noise abatement in noisy areas. PMID:23535280

  19. Quiet Spike(TradeMark) Build-up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    Flight tests of the Gulfstream Aerospace Corporation s Quiet Spike(TradeMark) hardware were recently completed on the National Aeronautics and Space Administration Dryden Flight Research Center F-15B airplane. NASA Dryden uses a modified F-15B (836) airplane as a testbed aircraft to cost-effectively fly flight research experiments that are typically mounted underneath the airplane, along the fuselage centerline. For the Quiet Spike(TradeMark) experiment, instead of a centerline mounting, a forward-pointing boom was attached to the radar bulkhead of the airplane. The Quiet Spike(TradeMark) experiment is a stepping-stone to airframe structural morphing technologies designed to mitigate the sonic-boom strength of business jets flying over land. Prior to flying the Quiet Spike(TradeMark) experiment on the F-15B airplane several ground vibration tests were required to understand the Quiet Spike(TradeMark) modal characteristics and coupling effects with the F-15B airplane. Because of flight hardware availability and compressed schedule requirements, a "traditional" ground vibration test of the mated F-15B Quiet Spike(TradeMark) ready-for-flight configuration did not leave sufficient time available for the finite element model update and flutter analyses before flight-testing. Therefore, a "nontraditional" ground vibration testing approach was taken. This report provides an overview of each phase of the "nontraditional" ground vibration testing completed for the Quiet Spike(TradeMark) project.

  20. Ionospheric manifestations of acoustic-gravity waves under quiet and disturbed conditions

    NASA Astrophysics Data System (ADS)

    Barabash, Vladimir; Chernogor, Leonid; Panasenko, Sergii; Domnin, Igor

    2014-05-01

    We present the observation results of wave disturbances in the ionosphere, which are known to be manifestations of atmospheric acoustic-gravity waves (AGWs). The observations have been conducted under quiet and naturally or artificially disturbed conditions by ionosonde and incoherent scatter radar located near Kharkiv, Ukraine. Wave disturbance parameters under quiet conditions were obtained and analysed during geophysical periods including vernal and autumn equinoxes as well as summer and winter solstices. The prevailing oscillation in ionospheric F2- layer had the period of 140 - 200 min and relative amplitude of 0.1 - 0.2. The duration of this oscillation changed from 5 - 7 to 24 hours, depending on a season. The amplitude of fluctuations with other periods was noticeably smaller. The time intervals at which the intensity of incoherent scatter signals varied quasi-periodically in the altitude range from 150 to 300 km were detected. The parameters of these variations were estimated using statistical analysis and bandpass filtering. The periods of wave processes were shown to be of 30 - 120 min, there durations did not exceed of 2 - 6 periods and relative amplitudes usually ranged from 0.03 to 0.15. The phase of oscillations was detected to propagate downwards. The vertical phase velocity of travelling ionospheric disturbances (TIDs) was estimated to be in the range from 50 to 200 m/s and increased with altitude. The observations of the partial solar eclipse on January, 4, 2011 near Kharkiv were used to study the ionospheric parameters in naturally disturbed conditions. The F2-layer critical frequency dropped by a factor of 2.1. The time delay of these variations with respect to the main magnitude of the solar disk obscuration was equal to about 16 minutes. The virtual height of signal reflection near the maximum of the F2-layer ionization increased by 70 km, and the height of the model parabolic layer increased by 10 km. Some decrease in electron density and

  1. Properties of the suprathermal heavy ion population near 1 AU during solar cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Dayeh, Maher A.; Desai, Mihir I.; Ebert, Robert W.; Mason, Glenn M.

    2016-03-01

    Using measurements from the Advanced Composition Explorer/Ultra-Low Energy Isotope Spectrometer (ACE/ULEIS) near 1 AU, we surveyed the composition and spectra of heavy ions (He-through-Fe) during interplanetary quiet times from 1998 January 1 to 2014 December 31 at suprathermal energies between ˜0.11 and ˜1.28 MeV nucleon-1. The selected time period covers the maxima of solar cycles 23 and 24 and the extended solar minimum in between. We find the following: (1) The number of quiet-hours in each year correlates well with the sunspot number, year 2009 was the quietest for about 90% of the time; (2) The composition of the quiet-time suprathermal heavy ion population (3He, C-through-O, and Fe) correlates well with the level of solar activity, exhibiting SEP-like composition signatures during solar maximum, and CIR- or solar wind-like composition during solar minimum; (3) The heavy ion spectra at ˜0.11-0.32 MeV nucleon-1 exhibit suprathermal tails with power-law spectral indices ranging from 1.4 to 2.7. (4) Fe spectral indices get softer (steeper) from solar minimum of cycle 23 to solar cycle 24 maximum. These results imply that during IP quiet times and at energies above ˜0.1 MeV nucleon-1, the IP medium is dominated by material from prior solar and interplanetary events.

  2. Determination of filling factors of Active Regions, Coronal Holes and Quiet Sun for the EIT archive 1997-2011

    NASA Astrophysics Data System (ADS)

    Verbeeck, Cis; Delouille, Veronique; De Visscher, Ruben; Mampaey, Benjamin; Haberreiter, Margit

    2013-04-01

    In previous work, we have proposed a multi-channel unsupervised spatially-constrained multichannel fuzzy clustering algorithm (SPoCA) that automatically segments EUV solar images into Active Regions (AR), Coronal Holes (CH), and Quiet Sun (QS). This algorithm has been running in near real time on AIA data as part of the SDO Feature Finding Team Project since 2010, populating the Heliophysics Events Knowledgebase (HEK) with Active Region and Coronal Hole events. After having corrected for the limb brightening effect, SPoCA computes an optimal clustering with respect to the regions of interest using fuzzy segmentation. The process is fast and automatic. Morphological dilation is employed to assemble neighboring bright AR cores into individual AR regions. Combining SPoCA's detection of AR, and CH on subsequent images allows automatic tracking and naming of any region of interest. We applied SPOCA on SOHO-EIT, SECCHI-EUVI, PROBA2-SWAP, and SDO-AIA, and show in particular the filling factors of AR/QS/CH as well as AR and CH mean intensity time series obtained from the full dataset of synoptic SOHO/EIT images taken between 1997 and 2011. Such segmentation can be used for several applications. Filling factors or AR, QS, and CH can be included into (semi-) empirical models of the solar atmosphere, which can in turn feed models of solar EUV irradiance. Another application is the investigation of active longitudes as well as long-term statistical studies of AR and CH parameters.

  3. Aeroelastic Calculations of Quiet High- Speed Fan Performed

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Srivastava, Rakesh; Mehmed, Oral; Min, James B.

    2002-01-01

    An advanced high-speed fan was recently designed under a cooperative effort between the NASA Glenn Research Center and Honeywell Engines & Systems. The principal design goals were to improve performance and to reduce fan noise at takeoff. Scale models of the Quiet High-Speed Fan were tested for operability, performance, and acoustics. During testing, the fan showed significantly improved noise characteristics, but a self-excited aeroelastic vibration known as flutter was encountered in the operating range. Flutter calculations were carried out for the Quiet High-Speed Fan using a three-dimensional, unsteady aerodynamic, Reynolds-averaged Navier-Stokes turbomachinery code named "TURBO." The TURBO code can accurately model the viscous flow effects that can play an important role in various aeroelastic problems such as flutter with flow separation, flutter at high loading conditions near the stall line (stall flutter), and flutter in the presence of shock and boundary-layer interaction. Initially, calculations were performed with no blade vibrations. These calculations were at a constant rotational speed and a varying mass flow rate. The mass flow rate was varied by changing the backpressure at the exit boundary of the computational domain. These initial steady calculations were followed by aeroelastic calculations in which the blades were prescribed to vibrate harmonically in a natural mode, at a natural frequency, and with a fixed interblade phase angle between adjacent blades. The AE-prep preprocessor was used to interpolate the in-vacuum mode shapes from the structural dynamics mesh onto the computational fluid dynamics mesh and to smoothly propagate the grid deformations from the blade surface to the interior points of the grid. The aeroelastic calculations provided the unsteady aerodynamic forces on the blade surface due to blade vibrations. These forces were vector multiplied with the structural dynamic mode shape to calculate the work done on the blade during

  4. The Role of Velocity Redistribution in Enhancing the Intensity of the He II 304 A Line in the Quiet Sun Spectrum

    NASA Technical Reports Server (NTRS)

    Andretta, Vincenzo; Jordan, Stuart D.; Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.; Behring, William E.; Thompson, William T.; Garcia, Adriana

    1999-01-01

    We present observational evidence of the effect of small scale ("microturbulent") velocities in enhancing the intensity of the He II lambda304 line with respect to other transition region emission lines, a process we call "velocity redistribution". We first show results from the 1991 and 1993 flights of SERTS (Solar EUV Rocket Telescope and Spectrograph). The spectral resolution of the SERTS instrument was sufficient to infer that, at the spatial resolution of 5", the line profile is nearly gaussian both in the quiet Sun and in active regions. We were then able to determine, for the quiet Sun, a lower limit for the amplitude of non-thermal motions in the region of formation of the 304 A line of the order of 10 km/s. We estimated that, in the presence of the steep temperature gradients of the solar Transition Region (TR), velocities of this magnitude can significantly enhance the intensity of that line, thus at least helping to bridge the gap between calculated and observed values. We also estimated the functional dependence of such an enhancement on the relevant parameters (non-thermal velocities, temperature gradient, and pressure). We then present results from a coordinated campaign, using SOHO/CDS and H-alpha spectroheliograms from Coimbra Observatory, aimed at determining the relationship between regions of enhanced helium emission and chromospheric velocity fields and transition region emission in the quiescent atmosphere. Using these data, we examined the behavior of the He II lambda304 line in the quiet Sun supergranular network and compared it with other TR lines, in particular with O III lambda600. We also examined the association of 304 A emission with the so-called "coarse dark mottle", chromospheric structures seen in H-alpha red wing images and associated with spicules. We found that all these observations are consistent with the velocity redistribution picture.

  5. Preliminary QCGAT program test results. [Quiet, Clean General Aviation Turbofan

    NASA Technical Reports Server (NTRS)

    Koenig, R. W.; Sievers, G. K.

    1979-01-01

    The paper presents the NASA Lewis program to demonstrate that large engine technology can be applied to general aviation engines to reduce noise, emissions, and fuel consumption. After a Phase I study, two contractors, Garrett AiResearch and AVCO-Lycoming, were selected to design, manufacture, assemble, test, and deliver their Quiet, Clean, General Aviation Turbofan (QCGAT) engines to NASA. Noise, emission, and performance goals and how well they were met are discussed. Noise goals involve take off noise 3.5 n. mi. from runway threshold, sideline noise at .25 n mi. and approach noise 1 n mi. from the runway at an altitude of 370 ft. The AiResearch engines power a stretched Learjet 35 and the Lycoming a specially conceived Beech executive jet, resulting in differing power goals. Thus the thrust goal for the Lycoming was 1622 lb. while the AiResearch goal was 3937 lb. Cruise thrust goals were 485 lb. at Mach 0.6 at 25,000 ft. and 903 lb. at Mach 0.8 at 40,000 ft. respectively. The design of both engines, based on existing cores, is studied, noting such special QCGAT features as new reduction gears, combustor and power turbine. Test results are given, indicating that while the goals for noise and thrust were met those for emissions were only partially met.

  6. Local area networking in a radio quiet environment

    NASA Astrophysics Data System (ADS)

    Childers, Edwin L.; Hunt, Gareth; Brandt, Joseph J.

    2002-11-01

    The Green Bank facility of the National Radio Astronomy Observatory is spread out over 2,700 acres in the Allegheny Mountains of West Virginia. Good communication has always been needed between the radio telescopes and the control buildings. The National Radio Quiet Zone helps protect the Green Bank site from radio transmissions that interfere with the astronomical signals. Due to stringent Radio Frequency Interference (RFI) requirements, a fiber optic communication system was used for Ethernet transmissions on the site and coaxial cable within the buildings. With the need for higher speed communications, the entire network has been upgraded to use optical fiber with modern Ethernet switches. As with most modern equipment, the implementation of the control of the newly deployed Green Bank Telescope (GBT) depends heavily on TCP/IP. In order to protect the GBT from the commodity Internet, the GBT uses a non-routable network. Communication between the control building Local Area Network (LAN) and the GBT is implemented using a Virtual LAN (VLAN). This configuration will be extended to achieve isolation between trusted local user systems, the GBT, and other Internet users. Legitimate access to the site, for example by remote observers, is likely to be implemented using a virtual private network (VPN).

  7. The quiet revolution in Asia's rice value chains.

    PubMed

    Reardon, Thomas; Chen, Kevin Z; Minten, Bart; Adriano, Lourdes; Dao, The Anh; Wang, Jianying; Gupta, Sunipa Das

    2014-12-01

    There is a rapid transformation afoot in the rice value chain in Asia. The upstream is changing quickly-farmers are undertaking capital-led intensification and participating in burgeoning markets for land rental, fertilizer and pesticides, irrigation water, and seed, and shifting from subsistence to small commercialized farms; in some areas landholdings are concentrating. Midstream, in wholesale and milling, there is a quiet revolution underway, with thousands of entrepreneurs investing in equipment, increasing scale, diversifying into higher quality, and the segments are undergoing consolidation and vertical coordination and integration. Mills, especially in China, are packaging and branding, and building agent networks in wholesale markets, and large mills are building direct relationships with supermarkets. The downstream retail segment is undergoing a "supermarket revolution," again with the lead in change in China. In most cases the government is not playing a direct role in the market, but enabling this transformation through infrastructural investment. The transformation appears to be improving food security for cities by reducing margins, offering lower consumer rice prices, and increasing quality and diversity of rice. This paper discusses findings derived from unique stacked surveys of all value chain segments in seven zones, more and less developed, around Bangladesh, China, India, and Vietnam. PMID:24735399

  8. Radio Quiet Zones (RQZ) - Working with national communication administrations

    NASA Astrophysics Data System (ADS)

    Tzioumis, Anastasios

    Radio Astronomy detects extremely faint radio signals from space, and hence is very susceptible to Radio Frequency Interference (RFI) from other radio communication services. Although radio astronomy has been allocated some radio bands by the International Telecommunications Union (ITU), cosmic radio emissions occur over the whole of the electromagnetic spectrum. Thus, there is a need for radio telescopes to operate over very wide radio bands and avoid RFI. Radio Quiet Zones (RQZ) in various forms have been implemented around many radio astronomy observatories, to minimise the impact of RFI on radio astronomy observations by coordinating with nearby radiocommunication services. The history and characteristics of such RQZ around the world will be reviewed, with emphasis on recent experience. For the next generation radio astronomy telescopes such as the Square Kilometre Array (SKA), it will be of critical importance to minimise RFI over the whole operating frequency range 200 MHz - 25 GHz. Progress towards establishing strict RQZ for the SKA will be reviewed. The main experience and lesson learned is that it is critical to work closely with national communication administrations. Work on RQZ in international bodies and the implications for radio sciences will also be discussed.

  9. Compact radio cores in radio-quiet active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Maini, A.; Prandoni, I.; Norris, R. P.; Giovannini, G.; Spitler, L. R.

    2016-04-01

    Context. The mechanism of radio emission in radio-quiet (RQ) active galactic nuclei (AGNs) is still debated and might arise from the central AGN, from star formation activity in the host, or from either of these sources. A direct detection of compact and bright radio cores embedded in sources that are classified as RQ can unambiguously determine whether a central AGN significantly contributes to the radio emission. Aims: We search for compact, high-surface-brightness radio cores in RQ AGNs that are caused unambiguously by AGN activity. Methods: We used the Australian Long Baseline Array to search for compact radio cores in four RQ AGNs located in the Extended Chandra Deep Field South (ECDFS). We also targeted four radio-loud (RL) AGNs as a control sample. Results: We detected compact and bright radio cores in two AGNs that are classified as RQ and in one that is classified as RL. Two RL AGNs were not imaged because the quality of the observations was too poor. Conclusions: We report on a first direct evidence of radio cores in RQ AGNs at cosmological redshifts. Our detections show that some of the sources that are classified as RQ contain an active AGN that can contribute significantly (~50% or more) to the total radio emission.

  10. Quiet transcranial magnetic stimulation: Status and future directions.

    PubMed

    Peterchev, Angel V; Murphy, David L K; Goetz, Stefan M

    2015-01-01

    A significant limitation of transcranial magnetic stimulation (TMS) is that the magnetic pulse delivery is associated with a loud clicking sound as high as 140 dB resulting from electromagnetic forces. The loud noise significantly impedes both basic research and clinical applications of TMS. It effectively makes TMS less focal since every click activates auditory cortex, brainstem, and other connected regions, synchronously with the magnetic pulse. The repetitive clicking sound can induce neuromodulation that can interfere with and confound the intended effects at the TMS target. As well, there are known concerns regarding blinding of TMS studies, hearing loss, induction of tinnitus, as well as tolerability. Addressing this need, we are developing a quiet TMS (qTMS) device that incorporates two key concepts: First, the dominant frequency components of the TMS pulse sound (typically 2-5 kHz) are shifted to higher frequencies that are above the human hearing upper threshold of about 20 kHz. Second, the TMS coil is designed electrically and mechanically to generate suprathreshold electric field pulses while minimizing the sound emitted at audible frequencies (<; 20 kHz). The enhanced acoustic properties of the coil are accomplished with a novel, layered coil design. We summarize a proof-of-concept qTMS prototype demonstrating noise loudness reduction by 19 dB(A) with ultrabrief pulses at conventional amplitudes. Further, we outline next steps to accomplish further sound reduction and suprathreshold pulse amplitudes. PMID:26736241

  11. Modeling the Chromosphere of a Sunspot and the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Avrett, E.; Tian, H.; Landi, E.; Curdt, W.; Wülser, J.-P.

    2015-10-01

    Semiempirical atmospheric modeling attempts to match an observed spectrum by finding the temperature distribution and other physical parameters along the line of sight through the emitting region such that the calculated spectrum agrees with the observed one. In this paper we take the observed spectrum of a sunspot and the quiet Sun in the EUV wavelength range 668–1475 Å from the 2001 SUMER atlas of Curdt et al. to determine models of the two atmospheric regions, extending from the photosphere through the overlying chromosphere into the transition region. We solve the coupled statistical equilibrium and optically thick radiative transfer equations for a set of 32 atoms and ions. The atoms that are part of molecules are treated separately, and are excluded from the atomic abundances and atomic opacities. We compare the Mg ii k line profile observations from the Interface Region Imaging Spectrograph with the profiles calculated from the two models. The calculated profiles for the sunspot are substantially lower than the observed ones, based on the SUMER models. The only way we have found to raise the calculated Mg ii lines to agree with the observations is to introduce illumination of the sunspot from the surrounding active region.

  12. Driver perceptions of the safety implications of quiet electric vehicles.

    PubMed

    Cocron, Peter; Krems, Josef F

    2013-09-01

    Previous research on the safety implications of quiet electric vehicles (EVs) has mostly focused on pedestrians' acoustic perception of EVs, and suggests that EVs are more difficult for pedestrians to hear and, therefore, compromise traffic safety. The two German field studies presented here examine the experiences of 70 drivers with low noise emissions of EVs and the drivers' long-term evaluation of the issue. Participants were surveyed via interviews and questionnaires before driving an EV for the first time, after 3 months of driving, and in the first study, again after 6 months. Based on participants' reports, a catalogue of safety-relevant incidents was composed in Study 1. The catalogue revealed that low noise-related critical incidents only rarely occur, and mostly take place in low-speed environments. The degree of hazard related to these incidents was rated as low to medium. In Study 1, driver concern for vulnerable road users as a result of low noise diminished with increasing driving experience, while perceived comfort due to this feature increased. These results were replicated in Study 2. In the second study, it was additionally examined, if drivers adjust their perceived risk of harming other road users over time. Results show that the affective assessment of risk also decreased with increased driving experience. Based on individual experience, drivers adjust their evaluation of noise-related hazards, suggesting that dangers associated with low noise emissions might be less significant than previously expected. PMID:23727553

  13. On the origin of radio emission in radio quiet quasars

    NASA Astrophysics Data System (ADS)

    Laor, Ari; Behar, Ehud

    The radio emission in radio loud quasars (RLQs) originates in a jet carrying relativistic electrons. In radio quiet quasars (RQQs) the radio emission is ˜ 103 times weaker, relative to other bands. Its origin is not clearly established yet, but it is often speculated to arise from a weak jet. Here we show that there is a tight relation between L_R and L_X for RQQs, with L_R/L_X˜ 10-5, based on the optically selected Palomar-Green (PG) quasars, with nearly complete X-ray and radio detections (avoiding biases and selection effects). Coronally active stars also show a tight relation between L_R and L_X with L_R/L_X˜ 10-5 (the Güdel & Benz relation), which together with correlated variability indicates that stellar coronae are magnetically heated. The X-ray emission of quasars most likely originates from a hot accretion disk corona, and since RQQs follow the Güdel & Benz relation, it is natural to associate their radio emission with coronal emission as well. The tight relation between L_R and L_X may simply reflect the equality of accretion disk coronal heating by magnetically generated relativistic electrons (producing L_R), and coronal cooling by Compton scattering (producing L_X). This suggestion can be tested by looking for correlated X-ray and radio variability patterns, such as the Neupert effect, displayed by stellar coronae.

  14. Quiet Down: Help Students Hear You by Turning Down the Volume on Your Management Techniques

    ERIC Educational Resources Information Center

    Parpos, Suzanna

    2005-01-01

    This teacher always thought that it was the loudest voices that got heard, but she was wrong. In this document, a teacher shares the greatest tool she has discovered in teaching inner city youth, her quiet voice.

  15. Promoting rest using a quiet time innovation in an adult neuroscience step down unit.

    PubMed

    Bergner, Tara

    2014-01-01

    Sleep and rest are fundamental for the restoration of energy needed to recuperate from illness, trauma and surgery. At present hospitals are too noisy to promote rest for patients. A literature search produced research that described how quiet time interventions addressing noise levels have met with positive patient and staff satisfaction, as well as creating a more peaceful and healing environment. In this paper, a description of the importance of quiet time and how a small butfeasible innovation was carried out in an adult neuroscience step down unit in a large tertiary health care facility in Canada is provided. Anecdotal evidence from patients, families, and staff suggests that quiet time may have positive effects for patients, their families, and the adult neuroscience step down unit staff Future research examining the effect of quiet time on patient, family and staff satisfaction and patient healing is necessary. PMID:25638912

  16. Supersonic quiet-tunnel development for laminar-turbulent transition research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1995-01-01

    This grant supported research into quiet-flow supersonic wind-tunnels, between February 1994 and February 1995. Quiet-flow nozzles operate with laminar nozzle-wall boundary layers, in order to provide low-disturbance flow for studies of laminar-turbulent transition under conditions comparable to flight. Major accomplishments include: (1) development of the Purdue Quiet-Flow Ludwieg Tube, (2) computational evaluation of the square nozzle concept for quiet-flow nozzles, and (3) measurement of the presence of early transition on the flat sidewalls of the NASA LaRC Mach 3.5 supersonic low-disturbance tunnel. Since items (1) and (2) are described in the final report for companion grant NAG1-1133, only item (3) is described here. A thesis addressing the development of square nozzles for high-speed, low-disturbance wind tunnels is included as an appendix.

  17. Quiet zone within a seismic gap near western Nicaragua: Possible location of a future large earthquake

    USGS Publications Warehouse

    Harlow, D.H.; White, R.A.; Cifuentes, I.L.; Aburto, Q.A.

    1981-01-01

    A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone. Copyright ?? 1981 AAAS.

  18. Stability of a double inverted pendulum model during human quiet stance with continuous delay feedback control.

    PubMed

    Suzuki, Yasuyuki; Nomura, Taishin; Morasso, Pietro

    2011-01-01

    Recent debate about neural mechanisms for stabilizing human upright quiet stance focuses on whether the active and time delay neural feedback control generating muscle torque is continuous or intermittent. A single inverted pendulum controlled by the active torque actuating the ankle joint has often been used for the debate on the presumption of well-known ankle strategy hypothesis claiming that the upright quiet stance can be stabilized mostly by the ankle torque. However, detailed measurements are showing that the hip joint angle exhibits amount of fluctuations comparable with the ankle joint angle during natural postural sway. Here we analyze a double inverted pendulum model during human quiet stance to demonstrate that the conventional proportional and derivative delay feedback control, i.e., the continuous delay PD control with gains in the physiologically plausible range is far from adequate as the neural mechanism for stabilizing human upright quiet stance. PMID:22256061

  19. Attractive "quiet" courtyards: a potential modifier of urban residents' responses to road traffic noise?

    PubMed

    Gidlöf-Gunnarsson, Anita; Ohrström, Evy

    2010-09-01

    The present paper explores the influence of the physical environmental qualities of "quiet". courtyards (degree of naturalness and utilization) on residents' noise responses. A questionnaire study was conducted in urban residential areas with road-traffic noise exposure between L(Aeq,24h) 58 to 68 dB at the most exposed façade. The dwellings had "quiet" indoor section/s and faced a "quiet" outdoor courtyard (L(Aeq,24h) < 48 dB façade reflex included). Data were collected from 385 residents and four groups were formed based on sound-level categories (58-62 and 63-68 dB) and classification of the "quiet" courtyards into groups with low and high physical environmental quality. At both sound-level categories, the results indicate that access to high-quality "quiet" courtyards is associated with less noise annoyance and noise-disturbed outdoor activities among the residents. Compared to low-quality "quiet" courtyards, high-quality courtyards can function as an attractive restorative environment providing residents with a positive soundscape, opportunities for rest, relaxation and play as well as social relations that potentially reduce the adverse effects of noise. However, access to quietness and a high-quality courtyard can only compensate partly for high sound levels at façades facing the streets, thus, 16% and 29% were still noise annoyed at 58-62 and 63-68 dB, respectively. Implications of the "quiet"-side concept are discussed. PMID:20948929

  20. Quiet Spike(TradeMark) Build-up Ground Vibration Testing Approach

    NASA Technical Reports Server (NTRS)

    Spivey, Natalie D.; Herrera, Claudia Y.; Truax, Roger; Pak, Chan-gi; Freund, Donald

    2007-01-01

    Flight tests of Gulfstream Aerospace Corporation s Quiet Spike(TradeMark) hardware were recently completed on the NASA Dryden Flight Research Center F-15B airplane. NASA Dryden uses a modified F-15B airplane as a testbed aircraft to cost-effectively fly flight research experiments that are typically mounted underneath the F-15B airplane, along the fuselage centerline. For the Quiet Spike(TradeMark) experiment, however, instead of a centerline mounting, a relatively long forward-pointing boom was attached to the radar bulkhead of the F-15B airplane. The Quiet Spike(TradeMark) experiment is a stepping-stone to airframe structural morphing technologies designed to mitigate the sonic-boom strength of business jets over land. The Quiet Spike(TradeMark) boom is a concept in which an aircraft s noseboom would be extended prior to supersonic acceleration. This morphing effectively lengthens the aircraft, thus reducing the peak sonic-boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, noncoalescing shocklets. Prior to flying the Quiet Spike(TradeMark) experiment on the F-15B airplane several ground vibration tests were required to understand the Quiet Spike(TradeMark) modal characteristics and coupling effects with the F-15B airplane. However, due to the flight hardware availability and compressed schedule requirements, a "traditional" ground vibration test of the mated F-15B Quiet Spike(TradeMark) ready-for- flight configuration did not leave sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. This paper provides an overview of each phase of the "nontraditional" ground vibration testing completed for the Quiet Spike(TradeMark) project which includes the test setup details, instrumentation layout, and modal results obtained in support of the structural dynamic modeling and flutter

  1. The horse-collar aurora - A frequent pattern of the aurora in quiet times

    NASA Technical Reports Server (NTRS)

    Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Evans, D. S.; Newell, P. T.

    1989-01-01

    The frequent appearance of the 'horse-collar aurora' pattern in quiet-time DE 1 images is reported, presenting a two-hour image sequence that displays the basic features and shows that it sometimes evolves toward the theta configuration. There is some evidence for interplanetary magnetic field B(y) influence on the temporal development of the pattern. A preliminary statistical analysis finds the pattern appearing in one-third or more of the image sequences recorded during quiet times.

  2. Beta EEG reflects sensory processing in active wakefulness and homeostatic sleep drive in quiet wakefulness.

    PubMed

    Grønli, Janne; Rempe, Michael J; Clegern, William C; Schmidt, Michelle; Wisor, Jonathan P

    2016-06-01

    Markers of sleep drive (<10 Hz; slow-wave activity and theta) have been identified in the course of slow-wave sleep and wakefulness. So far, higher frequencies in the waking electroencephalogram have not been examined thoroughly as a function of sleep drive. Here, electroencephalogram dynamics were measured in epochs of active wake (wake characterized by high muscle tone) or quiet wake (wake characterized by low muscle tone). It was hypothesized that the higher beta oscillations (15-35 Hz, measured by local field potential and electroencephalography) represent fundamentally different processes in active wake and quiet wake. In active wake, sensory stimulation elevated beta activity in parallel with gamma (80-90 Hz) activity, indicative of cognitive processing. In quiet wake, beta activity paralleled slow-wave activity (1-4 Hz) and theta (5-8 Hz) in tracking sleep need. Cerebral lactate concentration, a measure of cerebral glucose utilization, increased during active wake whereas it declined during quiet wake. Mathematical modelling of state-dependent dynamics of cortical lactate concentration was more precisely predictive when quiet wake and active wake were included as two distinct substates rather than a uniform state of wakefulness. The extent to which lactate concentration declined in quiet wake and increased in active wake was proportionate to the amount of beta activity. These data distinguish quiet wake from active wake. Quiet wake, particularly when characterized by beta activity, is permissive to metabolic and electrophysiological changes that occur in slow-wave sleep. These data urge further studies on state-dependent beta oscillations across species. PMID:26825702

  3. Bright Points in the Quiet Sun as Observed in the Visible and Near-UV by the Balloon-borne Observatory SUNRISE

    NASA Astrophysics Data System (ADS)

    Riethmüller, T. L.; Solanki, S. K.; Martínez Pillet, V.; Hirzberger, J.; Feller, A.; Bonet, J. A.; Bello González, N.; Franz, M.; Schüssler, M.; Barthol, P.; Berkefeld, T.; del Toro Iniesta, J. C.; Domingo, V.; Gandorfer, A.; Knölker, M.; Schmidt, W.

    2010-11-01

    Bright points (BPs) are manifestations of small magnetic elements in the solar photosphere. Their brightness contrast not only gives insight into the thermal state of the photosphere (and chromosphere) in magnetic elements, but also plays an important role in modulating the solar total and spectral irradiance. Here, we report on simultaneous high-resolution imaging and spectropolarimetric observations of BPs using SUNRISE balloon-borne observatory data of the quiet Sun at the disk center. BP contrasts have been measured between 214 nm and 525 nm, including the first measurements at wavelengths below 388 nm. The histograms of the BP peak brightness show a clear trend toward broader contrast distributions and higher mean contrasts at shorter wavelengths. At 214 nm, we observe a peak brightness of up to five times the mean quiet-Sun value, the highest BP contrast so far observed. All BPs are associated with a magnetic signal, although in a number of cases it is surprisingly weak. Most of the BPs show only weak downflows, the mean value being 240 m s-1, but some display strong down- or upflows reaching a few km s-1.

  4. Magnetic Upflow Events in the Quiet-Sun Photosphere. I. Observations

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, S.; Rouppe van der Voort, L.; de la Cruz Rodríguez, J.

    2015-09-01

    Rapid magnetic upflows in the quiet-Sun photosphere were recently uncovered from both Sunrise/IMaX and Hinode/SOT observations. Here, we study magnetic upflow events (MUEs) from high-quality, high- (spatial, temporal, and spectral) resolution, and full Stokes observations in four photospheric magnetically sensitive Fe i lines centered at 5250.21, 6173.34, 6301.51, and 6302.50 Å acquired with the Swedish Solar Telescope (SST)/CRISP. We detect MUEs by subtracting in-line Stokes V signals from those in the far blue wing whose signal-to-noise ratio (S/N) ≥slant 7. We find a larger number of MUEs at any given time (2.0× {10}-2 arcsec-2), larger by one to two orders of magnitude, than previously reported. The MUEs appear to fall into four classes presenting different shapes of Stokes V profiles with (I) asymmetric double lobes, (II) single lobes, (III) double-humped (two same-polarity lobes), and (IV) three lobes (an extra blueshifted bump in addition to double lobes), of which less than half are single-lobed. We also find that MUEs are almost equally distributed in network and internetwork areas and they appear in the interior or at the edge of granules in both regions. Distributions of physical properties, except for horizontal velocity, of the MUEs (namely, Stokes V signal, size, line-of-sight velocity, and lifetime) are almost identical for the different spectral lines in our data. A bisector analysis of our spectrally resolved observations shows that these events host modest upflows and do not show a direct indication of the presence of supersonic upflows reported earlier. Our findings reveal that the numbers, types (classes), and properties determined for MUEs can strongly depend on the detection techniques used and the properties of the employed data, namely, S/Ns, resolutions, and wavelengths.

  5. EVIDENCE FOR QUASI-ISOTROPIC MAGNETIC FIELDS FROM HINODE QUIET-SUN OBSERVATIONS

    SciTech Connect

    Asensio Ramos, A.

    2009-08-20

    Some recent investigations of spectropolarimetric observations of the Zeeman effect in the Fe I lines at 630 nm carried out with the Hinode solar space telescope have concluded that the strength of the magnetic field vector in the internetwork regions of the quiet Sun is in the hG regime and that its inclination is predominantly horizontal. We critically reconsider the analysis of such observations and carry out a complete Bayesian analysis with the aim of extracting as much information as possible from them, including error bars. We apply the recently developed BAYES-ME code that carries out a complete Bayesian inference for Milne-Eddington atmospheres. The sampling of the posterior distribution function is obtained with a Markov Chain Monte Carlo scheme and the marginal distributions are analyzed in detail. The Kullback-Leibler divergence is used to study the extent to which the observations introduce new information in the inference process resulting in sufficiently constrained parameters. Our analysis clearly shows that only upper limits to the magnetic field strength can be inferred, with fields in the kG regime completely discarded. Furthermore, the noise level present in the analyzed Hinode observations induces a substantial loss of information for constraining the azimuth of the magnetic field. Concerning the inclination of the field, we demonstrate that some information is available to constrain it for those pixels with the largest polarimetric signal. The results also point out that the field in pixels with small polarimetric signals can be nicely reproduced in terms of a quasi-isotropic distribution.

  6. Development of quiet-flow supersonic wind tunnels for laminar-turbulent transition research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1994-01-01

    This grant supported research into quiet-flow supersonic wind-tunnels, between May 1990 and December 1994. Quiet-flow nozzles operate with laminar nozzle-wall boundary layers, in order to provide low-disturbance flow for studies of laminar-turbulent transition under conditions comparable to flight. Major accomplishments include: (1) the design, fabrication, and performance-evaluation of a new kind of quiet tunnel, a quiet-flow Ludweig tube; (2) the integration of preexisting codes for nozzle design, 2D boundary-layer computation, and transition-estimation into a single user-friendly package for quiet-nozzle design; and (3) the design and preliminary evaluation of supersonic nozzles with square cross-section, as an alternative to conventional quiet-flow nozzles. After a brief summary of (1), a description of (2) is presented. Published work describing (3) is then summarized. The report concludes with a description of recent results for the Tollmien-Schlichting and Gortler instability in one of the square nozzles previously analyzed.

  7. Solar limb brightening at 350 microns

    SciTech Connect

    Lindsey, C.; Hildebrand, R.H.; Keene, J.; Whitcomb, S.E.

    1981-09-01

    We have used the NASA Infrared Telescope Facility at Mauna Kea to observe the intensity profile of the quiet solar limb in the 300--400 ..mu..m continuum. We find a significant resolved brightening of several percent over the outer 60'' of the solar limb in this band. However, the magnitude of the brightening is considerably less than that indicated by earlier observations of a total solar eclipse in integrated Sun--Moon radiation by Beckman, Lesurf, and Ross in the 1.2 mm continuum.

  8. Feedforward ankle strategy of balance during quiet stance in adults

    PubMed Central

    Gatev, Plamen; Thomas, Sherry; Kepple, Thomas; Hallett, Mark

    1999-01-01

    We studied quiet stance investigating strategies for maintaining balance. Normal subjects stood with natural stance and with feet together, with eyes open or closed. Kinematic, kinetic and EMG data were evaluated and cross-correlated.Cross-correlation analysis revealed a high, positive, zero-phased correlation between anteroposterior motions of the centre of gravity (COG) and centre of pressure (COP), head and COG, and between linear motions of the shoulder and knee in both sagittal and frontal planes. There was a moderate, negative, zero-phased correlation between the anteroposterior motion of COP and ankle angular motion.Narrow stance width increased ankle angular motion, hip angular motion, mediolateral sway of the COG, and the correlation between linear motions of the shoulder and knee in the frontal plane. Correlations between COG and COP and linear motions of the shoulder and knee in the sagittal plane were decreased. The correlation between the hip angular sway in the sagittal and frontal planes was dependent on interaction between support and vision.Low, significant positive correlations with time lags of the maximum of cross-correlation of 250-300 ms were found between the EMG activity of the lateral gastrocnemius muscle and anteroposterior motions of the COG and COP during normal stance. Narrow stance width decreased both correlations whereas absence of vision increased the correlation with COP.Ankle mechanisms dominate during normal stance especially in the sagittal plane. Narrow stance width decreased the role of the ankle and increased the role of hip mechanisms in the sagittal plane, while in the frontal plane both increased.The modulation pattern of the lateral gastrocnemius muscle suggests a central program of control of the ankle joint stiffness working to predict the loading pattern. PMID:9882761

  9. Measurement of the CMB Polarization at 95 GHz from QUIET

    NASA Astrophysics Data System (ADS)

    Buder, Immanuel

    2012-09-01

    (Abridged) Despite the great success of precision cosmology, cosmologists cannot fully explain the initial conditions of the Universe. Inflation, an exponential expansion in the first 10^-36s, is a promising potential explanation. A generic prediction of inflation is odd-parity (B-mode) polarization in the cosmic microwave background (CMB). The Q/U Imaging ExperimenT (QUIET) aimed to limit or detect this polarization. We built a coherent pseudo-correlation microwave polarimeter. An array of mass-produced modules populated the focal plane of a 1.4m telescope. Each module had a sensitivity to polarization of 756muK sqrt{s} with a bandwidth of 10.7+/-1.1 GHz centered at 94.5+/-0.8 GHz; the combined sensitivity was 87+/-7muK sqrt{s}. We incorporated deck rotation, an absorbing ground screen, a new time-stream double-demodulation technique, and optimized optics into the design to reduce instrumental polarization. We observed with this instrument at the Atacama Plateau in Chile between August 2009 and December 2010. We collected 5336.9 hours of CMB observation and 1090 hours of astronomical calibration. This thesis describes the analysis and results of these data. We characterized the instrument using the astronomical calibration data as well as purpose-built artificial sources. We developed noise modeling, filtering, and data selection following a blind-analysis strategy. Central to this strategy was a suite of 32 null tests, each motivated by a possible instrumental problem or systematic effect. We also evaluated the systematic errors in the blind stage of the analysis before the result was known. We then calculated the CMB power spectra using a pseudo-Cl cross-correlation technique that suppressed contamination and made the result insensitive to noise bias.

  10. Io's Sodium Clouds and Plasma Torus: Three Quiet Apparitions

    NASA Astrophysics Data System (ADS)

    Wilson, Jody; Mendillo, M.; Baumgardner, J.

    2007-10-01

    Ground-based observations of Io's sodium clouds from February 2005 to June 2007 indicate that Io was in an unusually quiet state of atmospheric escape. Simultaneous observations of the sulfur-ion plasma torus in that same period indicate that the torus has been gradually dimming, which is also consistent with below-average atmospheric escape rates from Io. The S+ torus was essentially undetectable in May 2007. Our goal in this 3-year project was to compare variability in the clouds and torus with observations of Io's volcanic infrared ``hot spots'' (e.g., Marchis et al. 2005) in order to track the flow of mass from Io's volcanoes into Jupiter's magnetosphere. Of particular interest was the 18-month cycle of Io's large volcano Loki (Rathbun et al. 2002, Mendillo et al. 2004), however it seems that Loki has settled into an unusually long-term quiescent state (Rathbun and Spencer, 2006). Thus, although we have been unable to monitor the month-to-month effects of the Loki cycle, we nonetheless have indirect evidence for Loki's long-term effects on Io's atmosphere and Jupiter's magnetosphere by observing their weak states when Loki is not actively contributing. This research is funded in part by NASA's Planetary Astronomy Program. Marchis et al., Keck AO survey of Io global volcanic activity between 2 and 5 microns, Icarus, 176, 96-122, 2005. Mendillo et al., Io's volcanic control of Jupiter's extended neutral clouds, Icarus, 170, 430-442, 2004. Rathbun, J.A. et al., Loki, Io: A periodic volcano, Geophysical Research Letters, 29, Issue 10, pp. 84-1, 2002. Rathbun, J.A. and J.R. Spencer, Loki, Io: New ground-based observations and a model describing the change from periodic overturn, Geophysical Research Letters, 33, Issue 17, 2006.

  11. Quiet Eye Training Facilitates Competitive Putting Performance in Elite Golfers

    PubMed Central

    Vine, Samuel J.; Moore, Lee J.; Wilson, Mark R.

    2011-01-01

    The aim of this study was to examine the effectiveness of a brief quiet eye (QE) training intervention aimed at optimizing visuomotor control and putting performance of elite golfers under pressure, and in real competition. Twenty-two elite golfers (mean handicap 2.7) recorded putting statistics over 10 rounds of competitive golf before attending training individually. Having been randomly assigned to either a QE training or Control group, participants were fitted with an Applied Science Laboratories Mobile Eye tracker and performed 20 baseline (pre-test) putts from 10 ft. Training consisted of video feedback of their gaze behavior while they completed 20 putts; however the QE-trained group received additional instructions related to maintaining a longer QE period. Participants then recorded their putting statistics over a further 10 competitive rounds and re-visited the laboratory for retention and pressure tests of their visuomotor control and putting performance. Overall, the results were supportive of the efficacy of the QE training intervention. QE duration predicted 43% of the variance in putting performance, underlying its critical role in the visuomotor control of putting. The QE-trained group maintained their optimal QE under pressure conditions, whereas the Control group experienced reductions in QE when anxious, with subsequent effects on performance. Although their performance was similar in the pre-test, the QE-trained group holed more putts and left the ball closer to the hole on missed putts than their Control group counterparts in the pressure test. Importantly, these advantages transferred to the golf course, where QE-trained golfers made 1.9 fewer putts per round, compared to pre-training, whereas the Control group showed no change in their putting statistics. These results reveal that QE training, incorporated into a pre-shot routine, is an effective intervention to help golfers maintain control when anxious. PMID:21713182

  12. Relationships between Fluid Vorticity, Kinetic Helicity, and Magnetic Field on Small-scales (Quiet-Network) on the Sun

    NASA Astrophysics Data System (ADS)

    Sangeetha, C. R.; Rajaguru, S. P.

    2016-06-01

    We derive horizontal fluid motions on the solar surface over large areas covering the quiet-Sun magnetic network from local correlation tracking of convective granules imaged in continuum intensity and Doppler velocity by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. From these we calculate the horizontal divergence, the vertical component of vorticity, and the kinetic helicity of fluid motions. We study the correlations between fluid divergence and vorticity, and between vorticity (kinetic helicity) and the magnetic field. We find that the vorticity (kinetic helicity) around small-scale fields exhibits a hemispherical pattern (in sign) similar to that followed by the magnetic helicity of large-scale active regions (containing sunspots). We identify this pattern to be a result of the Coriolis force acting on supergranular-scale flows (both the outflows and inflows), consistent with earlier studies using local helioseismology. Furthermore, we show that the magnetic fields cause transfer of vorticity from supergranular inflow regions to outflow regions, and that they tend to suppress the vortical motions around them when magnetic flux densities exceed about 300 G (from HMI). We also show that such an action of the magnetic fields leads to marked changes in the correlations between fluid divergence and vorticity. These results are speculated to be of importance to local dynamo action (if present) and to the dynamical evolution of magnetic helicity at the small-scale.

  13. Cosmic ray albedo gamma rays from the quiet sun

    NASA Technical Reports Server (NTRS)

    Seckel, D.; Stanev, T.; Gaisser, T. K.

    1992-01-01

    We estimate the flux of gamma-rays that result from collisions of high energy galactic cosmic rays with the solar atmosphere. An important aspect of our model is the propagation of cosmic rays through the magnetic fields of the inner solar systems. We use diffusion to model propagation down to the bottom of the corona. Below the corona we trace particle orbits through the photospheric fields to determine the location of cosmic ray interactions in the solar atmosphere and evolve the resultant cascades. For our nominal choice of parameters, we predict an integrated flux of gamma rays (at 1 AU) of F(E(sub gamma) greater than 100 MeV) approximately = 5 x 10(exp -8)/sq cm sec. This can be an order of magnitude above the galactic background and should be observable by the Energetic Gamma Ray experiment telescope (EGRET).

  14. Harmonic quiet-day curves as magnetometer baselines for ionospheric current analyses

    NASA Astrophysics Data System (ADS)

    van de Kamp, M.

    2013-11-01

    This paper presents a novel method to determine a baseline for magnetometer data. This baseline consists of all magnetic field components not related to ionospheric and magnetospheric disturbances, i.e. all field components due to solar quiet variations and other background variations, such as tidal and secular variations, as well as equipment effects. Extraction of this baseline is useful when the magnetic field variations due to solar disturbances are analysed. This makes magnetometer data suitable, for instance, for the calculation of ionospheric equivalent currents related to geomagnetic storms and substorms. The full baseline is largely composed of two main constituents: the diurnal baseline and the long-term baseline. For the diurnal baseline, first "templates" are derived, based on the lowest few harmonics of the daily curves from the quietest days. The diurnal variation of the baseline is obtained by linear interpolation between these templates; this method ensures a smooth baseline at all times, avoiding any discontinuities at transitions between days. The long-term baseline is obtained by linear interpolation between the daily median values of the data; this way the baseline is ensured to follow long-term trends, such as seasonal and tidal variations, as well as equipment drift. The daily median values are calculated for all days except the most disturbed ones; a procedure for this selection is included. The method avoids many problems associated with traditional baseline methods and some of the other recently published methods, and is simpler in procedure than most other recent ones. As far as can be compared, the distribution of the resulting field after removal of the baseline is largely similar to that using other recent baseline methods. However, the main advantage of the method of this paper over others is that it removes equipment drift and other artefacts efficiently without discarding too much data, so that even low-quality data from remote

  15. Ionospheric response to the High Speed Solar Streams during last solar minimum

    NASA Astrophysics Data System (ADS)

    Mosna, Zbysek; Koucka Knizova, Petra; Georgieva, Katya

    Ionosphere is a highly variable system. Response of ionospheric plasma to the High Speed Solar Streams (HSS) by means of critical frequencies fof2, heights of maximum electron concentration hmf2 and the occurrence of sporadic E-layer during last prolonged solar minimum is presented and we compare it to previous studies. State of the ionosphere depends on the daytime, season, phase of solar cycle etc. The extent of ionospheric response to the solar event (HSS, CME etc.) is a subject of mentioned conditions and strength of solar event itself but it also significantly depends on the actual geomagnetic and ionospheric situation and the memory of the system, e.g. length of the preceding quiet or disturbed period. Ionospheric storms have been relatively widely studied. However, last solar minimum gives us an exceptional possibility to study ionospheric processes under conditions of unusually long time of low solar activity.

  16. Erosion of carbon/carbon by solar wind charged particle radiation during a solar probe mission

    NASA Technical Reports Server (NTRS)

    Sokolowski, Witold; O'Donnell, Tim; Millard, Jerry

    1991-01-01

    The possible erosion of a carbon/carbon thermal shield by solar wind-charged particle radiation is reviewed. The present knowledge of erosion data for carbon and/or graphite is surveyed, and an explanation of erosion mechanisms under different charged particle environments is discussed. The highest erosion is expected at four solar radii. Erosion rates are analytically estimated under several conservative assumptions for a normal quiet and worst case solar wind storm conditions. Mass loss analyses and comparison studies surprisingly indicate that the predicted erosion rate by solar wind could be greater than by nominal free sublimation during solar wind storm conditions at four solar radii. The predicted overall mass loss of a carbon/carbon shield material during the critical four solar radii flyby can still meet the mass loss mission requirement of less than 0.0025 g/sec.

  17. Improvement of background solar wind predictions

    NASA Astrophysics Data System (ADS)

    Dálya, Zsuzsanna; Opitz, Andrea

    2016-04-01

    In order to estimate the solar wind properties at any heliospheric positions propagation tools use solar measurements as input data. The ballistic method extrapolates in-situ solar wind observations to the target position. This works well for undisturbed solar wind, while solar wind disturbances such as Corotating Interaction Regions (CIRs) and Coronal Mass Ejections (CMEs) need more consideration. We are working on dedicated ICME lists to clean these signatures from the input data in order to improve our prediction accuracy. These ICME lists are created from several heliospheric spacecraft measurements: ACE, WIND, STEREO, SOHO, MEX and VEX. As a result, we are able to filter out these events from the time series. Our corrected predictions contribute to the investigation of the quiet solar wind and space weather studies.

  18. Submillimeter solar images from the JCMT

    SciTech Connect

    Kopp, G.; Lindsey, C.

    1992-01-01

    We present nearly full-disk, diffraction-limited solar images made at 350 and 850 [mu]m and at 1.3 mm from the 15 m James Clerk Maxwell Telescope on Mauna Kea. These wavelengths sample the thermal structure of the solar chromosphere at altitude from 500 to about 1500 km, providing a height-dependent diagnostic of the atmosphere. Filament channels and neutral lines are apparent in the submillimeter images, although filaments themselves are not clearly visible. The submillimeter images show plage approximately 20% brigher than the surrounding quiet Sun, while sunspot intensities are comparable to the quiet Sun. Circumfacules,' dark are similar to those seen in Ca 8542; comparison with Ca H and K may give estimates of the temperature and filing factor of the hot gas present in these probably bifurcated regions.

  19. Energy balance in solar and stellar chromospheres

    NASA Technical Reports Server (NTRS)

    Avrett, E. H.

    1981-01-01

    Net radiative cooling rates for quiet and active regions of the solar chromosphere and for two stellar chromospheres are calculated from corresponding atmospheric models. Models of chromospheric temperature and microvelocity distributions are derived from observed spectra of a dark point within a cell, the average sun and a very bright network element on the quiet sun, a solar plage and flare, and the stars Alpha Boo and Lambda And. Net radiative cooling rates due to the transitions of various atoms and ions are then calculated from the models as a function of depth. Large values of the net radiative cooling rate are found at the base of the chromosphere-corona transition region which are due primarily to Lyman alpha emission, and a temperature plateau is obtained in the transition region itself. In the chromospheric regions, the calculated cooling rate is equal to the mechanical energy input as a function of height and thus provides a direct constraint on theories of chromospheric heating.

  20. Realistic Modeling of Spontaneous Flow Eruptions in the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Kitiashvili, Irina; Yoon, Seokkwan S

    2014-06-01

    Ground and space observations reveal that the solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The origin and driving forces of the observed eruptions are still unknown. Using realistic numerical simulations we find that small-scale plasma eruptions can be produced by ubiquitous magnetized vortex tubes generated in the Sun's turbulent convection. The vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and strengthen the background magnetic field, and push surrounding material up, generating impulses of Alfven waves and shocks. Our simulations reveal complicated high-speed flows, thermodynamic, and magnetic structures in the erupting vortex tubes. We find that the eruptions are initiated in the subsurface layers, and initially are driven by high-pressure gradients in the subphotosphere and photosphere, and are accelerated by the Lorentz force in the higher atmospheric layers. The eruptions are often quasi-periodic with a characteristic period of 2-5 min. These vortex eruptions have a complicated flow helical pattern, with predominantly downward flows in the vortex tube cores and upward flows in their surroundings. For comparison with observations we calculate full Stokes profiles in different wavelength for different space and ground instruments, such as HMI/SDO, Hinode, NST/BBSO, IMaX/Sunrise. In particular, we find that the observed eruption events are not always associated with strong magnetic field concentrations, and that strong field patches can be a source of several simultaneous eruptions.

  1. Quiet eye training expedites motor learning and aids performance under heightened anxiety: the roles of response programming and external attention.

    PubMed

    Moore, Lee J; Vine, Samuel J; Cooke, Andrew; Ring, Christopher; Wilson, Mark R

    2012-07-01

    Quiet eye training expedites skill learning and facilitates anxiety-resistant performance. Changes in response programming and external focus of attention may explain such benefits. We examined the effects of quiet eye training on golf-putting performance, quiet eye duration, kinematics (clubhead acceleration), and physiological (heart rate, muscle activity) responses. Forty participants were assigned to a quiet eye or technical trained group and completed 420 baseline, training, retention, and pressure putts. The quiet eye group performed more accurately and displayed more effective gaze control, lower clubhead acceleration, greater heart rate deceleration, and reduced muscle activity than the technical trained group during retention and pressure tests. Thus, quiet eye training was linked to indirect measures of improved response programming and an external focus. Mediation analyses partially endorsed a response programming explanation. PMID:22564009

  2. Solar Wind Structure at 1 AU: Comparison between Solar Minima 22/23 and 23/24

    NASA Astrophysics Data System (ADS)

    Jian, L.; Russell, C.; Luhmann, J. G.; Galvin, A. B.; Skoug, R. M.; Schroeder, P. C.

    2009-12-01

    The current solar minimum 23/24 has been unusually long and deep, compared with the solar minima in the space era. In order to see the consequence of the extremely quiet Sun on the solar wind, we compare the solar wind structure during the current solar minimum with the last solar minimum 22/23, which represents the case of a short and shallow solar minimum. Based on ACE, Wind, and STEREO in situ plasma and magnetic field observations, we identify and characterize stream interaction regions (SIRs), interplanetary CMEs (ICMEs), interplanetary shocks, sector boundaries, and other structures in the solar wind at 1 AU for 1995 - 1997 and 2007 - 2009. The properties of these structures, such as the occurrence rate, SIR and ICME scale and interaction strength, shock Mach number, correlation between sector boundary and SIR, will be studied. In addition to the statistical study, we will present some case studies of events from this deep solar minimum.

  3. Intensity Distribution of the Solar Transition Region

    NASA Technical Reports Server (NTRS)

    Fisher, George H.

    1999-01-01

    The objective of this research project was to use high resolution spectroscopic observations from the SUMER instrument on SOHO to study the structure of the solar transition region. Our focus in this grant was to study the structure of the transition region in a small active region, and compare it to similar observations we made of the quiet Sun. We also used SXT and EIT data to constrain the coronal and transition region emission measure distribution.

  4. High speed magnetized flows in the quiet Sun

    NASA Astrophysics Data System (ADS)

    Quintero Noda, C.; Borrero, J. M.; Orozco Suárez, D.; Ruiz Cobo, B.

    2014-09-01

    Context. We analyzed spectropolarimetric data recorded with Hinode/SP in quiet-Sun regions located at the disk center. We found single-lobed Stokes V profiles showing highly blue- and red-shifted signals. Oftentimes both types of events appear to be related to each other. Aims: We aim to set constraints on the nature and physical causes of these highly Doppler-shifted signals, as well as to study their spatial distribution, spectropolarimetric properties, size, and rate of occurrence. Also, we plan to retrieve the variation of the physical parameters with optical depth through the photosphere. Methods: We have examined the spatial and polarimetric properties of these events using a variety of data from the Hinode spacecraft. We have also inferred the atmospheric stratification of the physical parameters by means of the inversion of the observed Stokes profiles employing the Stokes Inversion based on Response functions (SIR) code. Finally, we analyzed their evolution using a time series from the same instrument. Results: Blue-shifted events tend to appear over bright regions at the edge of granules, while red-shifted events are seen predominantly over dark regions on intergranular lanes. Large linear polarization signals can be seen in the region that connects them. The magnetic structure inferred from the time series revealed that the structure corresponds to a Ω-loop, with one footpoint always over the edge of a granule and the other inside an intergranular lane. The physical parameters obtained from the inversions of the observed Stokes profiles in both events show an increase with respect to the Harvard-Smithonian reference atmosphere in the temperature at log τ500 ∈ (-1, -3) and a strong magnetic field, B ≥ 1 kG, at the bottom of the atmosphere that quickly decreases upward until vanishing at log τ500 ≈ -2. In the blue-shifted events, the LOS velocities change from upflows at the bottom to downflows at the top of the atmosphere. Red-shifted events

  5. F15B-Quiet Spike Aeroservoelastic Flight Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.

    2007-01-01

    Airframe structural morphing technologies designed to mitigate sonic boom strength are being developed by Gulfstream Aerospace Corporation (GAC). Among these technologies is a concept in which an aircraft's frontend would be extended prior to supersonic acceleration. This morphing would effectively lengthen the vehicle, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. This combination of boom shaping techniques is predicted to transform the classic, high-impulse N-wave pattern typically generated by an aircraft traveling at supersonic speed into a signature more closely resembling a sinusoidal wave with a greatly reduced perceived loudness. 'QuietSpike' is GAC's nomenclature for its recently patented front-end vehicle morphing arrangement. The ability of Quiet Spike to effectively shape a vehicle's far- field sonic boom signature is highly dependent on the area distribution characteristics of the aircraft. The full aeroacoustic benefits of front-end morphing at farfield are only possible when the QuietSpike article and vehicle configuration are designed in consideration of each other. Adding QuietSpike technology to the airframe of an existing, non-boom-optimized supersonic vehicle is unlikely to result in an improved far-field signature due to the generally over-powering influence of wing- and inlet-generated shocks. Therefore, it is generally recognized within NASA and the industry that a clean-sheet vehicle design is required to demonstrate the theoretically predicted far-field aeroacoustic benefits of QuietSpike type morphing and other boom- mitigating concepts. NASA's Aeronautics Research Mission Directorate (ARMD) Supersonics Division has placed increased priority on near-term development and flight-testing of such a vehicle. To help achieve this objective, static and dynamic aerostructural proof-of-concept testing was considered a prudent step

  6. Flight Testing of the Gulfstream Quiet Spike(TradeMark) on a NASA F-15B

    NASA Technical Reports Server (NTRS)

    Smolka, James W.; Cowert, Robert A.; Molzahn, Leslie M.

    2007-01-01

    Gulfstream Aerospace has long been interested in the development of an economically viable supersonic business jet (SBJ). A design requirement for such an aircraft is the ability for unrestricted supersonic flight over land. Although independent studies continue to substantiate that a market for a SBJ exists, regulatory and public acceptance challenges still remain for supersonic operation over land. The largest technical barrier to achieving this goal is sonic boom attenuation. Gulfstream's attention has been focused on fundamental research into sonic boom suppression for several years. This research was conducted in partnership with the NASA Aeronautics Research Mission Directorate (ARMD) supersonic airframe cruise efficiency technical challenge. The Quiet Spike, a multi-stage telescopic nose boom and a Gulfstream-patented design (references 1 and 2), was developed to address the sonic boom attenuation challenge and validate the technical feasibility of a morphing fuselage. The Quiet Spike Flight Test Program represents a major step into supersonic technology development for sonic boom suppression. The Gulfstream Aerospace Quiet Spike was designed to reduce the sonic boom signature of the forward fuselage for an aircraft flying at supersonic speeds. In 2004, the Quiet Spike Flight Test Program was conceived by Gulfstream and NASA to demonstrate the feasibility of sonic boom mitigation and centered on the structural and mechanical viability of the translating test article design. Research testing of the Quiet Spike consisted of numerous ground and flight operations. Each step in the process had unique objectives, and involved numerous test team members from the NASA Dryden Flight Research Center (DFRC) and Gulfstream Aerospace. Flight testing of the Quiet Spike was conducted at the NASA Dryden Flight Research Center on an F-15B aircraft from August, 2006, to February, 2007. During this period, the Quiet Spike was flown at supersonic speeds up to Mach 1.8 at the

  7. Third Advances in Solar Physics Euroconference: Magnetic Fields and Oscillations

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Hofmann, A.; Staude, J.

    The third Advances in Solar Physics Euroconference (ASPE) "Magnetic Fields and Oscillations"concluded a series of three Euroconferences sponsored by the European Union. The meeting took place in Caputh near Potsdam, Germany, on September 22-25, 1998, followed by the JOSO (Joint Organization for Solar Observations) 30th Annual Board Meeting on September 26, 1998. The ASPE formula is attractive and compares well with other meetings with "show-and-tell" character. This meeting had 122 participants coming from 26 countries; 36 participants came from countries formerly behind the Iron Curtain; a "politically incorrect" estimate says that 48 participants were below 35 years of age, with an unusually large female-to-male ratio. This characteristic of youngness is the more striking since solar physics is a perhaps overly established field exhibiting an overly senior age profile. It was a good opportunity to train this young generation in Solar Physics. The conference topic "Magnetic Fields and Oscillations" obviously was wide enough to cater to many an interest. These proceedings are organized according to the structure of the meeting. They include the topics 'High resolution spectropolarimetry and magnetometry', 'Flux-tube dynamics', 'Modelling of the 3-D magnetic field structure', 'Mass motions and magnetic fields in sunspot penumbral structures', 'Sunspot oscillations', 'Oscillations in active regions - diagnostics and seismology', 'Network and intranetwork structure and dynamics', and 'Waves in magnetic structures'. These topics covered the first 2.5 days of the conference. The reviews, oral contributions, and poster presentations were by no means all of the meeting. The ASPE formula also adds extensive plenary sessions of JOSO Working groups on topics that involve planning of Europe-wide collaboration. At this meeting these concerned solar observing techniques, solar data bases, coordination between SOHO and ground-based observing, and preparations for August 11, 1999

  8. Mass composition and dynamics in quiet sun prominences

    NASA Astrophysics Data System (ADS)

    Kilper, Gary K.

    2009-06-01

    Solar prominences are transient phenomena in the solar atmosphere that display highly dynamic activity and can result in dramatic eruptions, ejecting a large amount of material into the heliosphere. The dynamics of the prominence plasma reveal information about its interaction with the magnetic field of the prominence, while the eruptions are associated with coronal mass ejections, which greatly affect space weather near Earth and throughout the solar system. My research on these topics was conducted via observational analyses of the partially-ionized prominence material, its composition, and the dynamics over time in prominences that range in activity from quiescent to highly active. The main results are evidence that (1) in quiescent prominences, neutral He is located more in the lower part of the structure, (2) a higher level of activity in prominences is related to a mixing of the material, and (3) an extended period of high activity and mixing occurs prior to eruptions, possibly due to mass loading. In addition, innovative modifications to analytical techniques led to measurements of the material's mass, composition, and small-scale dynamics.

  9. Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence

    SciTech Connect

    Chapman, S. C.; Nicol, R. M.

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum - with turbulent fluctuations down by a factor of approx2 in power - provides a test of this invariance.

  10. Generalized similarity in finite range solar wind magnetohydrodynamic turbulence.

    PubMed

    Chapman, S C; Nicol, R M

    2009-12-11

    Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterizes this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum--with turbulent fluctuations down by a factor of approximately 2 in power--provides a test of this invariance. PMID:20366193

  11. Solar Coronal Plumes and the Fast Solar Wind

    NASA Astrophysics Data System (ADS)

    Dwivedi, Bhola N.; Wilhelm, Klaus

    2015-03-01

    The spectral profiles of the coronal Ne viii line at 77 nm have different shapes in quiet-Sun regions and Coronal Holes (CHs). A single Gaussian fit of the line profile provides an adequate approximation in quiet-Sun areas, whereas, a strong shoulder on the long-wavelength side is a systematic feature in CHs. Although this has been noticed since 1999, no physical reason for the peculiar shape could be given. In an attempt to identify the cause of this peculiarity, we address three problems that could not be conclusively resolved, in a review article by a study team of the International Space Science Institute (ISSI) (Wilhelm et al. 2011): (1) The physical processes operating at the base and inside of plumes, as well as their interaction with the Solar Wind (SW). (2) The possible contribution of plume plasma to the fast SW streams. (3) The signature of the First-Ionization Potential (FIP) effect between plumes and inter-plume regions (IPRs). Before the spectroscopic peculiarities in IPRs and plumes in Polar Coronal Holes (PCHs) can be further investigated with the instrument Solar Ultraviolet Measurements of Emitted Radiation (SUMER) aboard the Solar and Heliospheric Observatory (SOHO), it is mandatory to summarize the results of the review to place the spectroscopic observations into context. Finally, a plume model is proposed that satisfactorily explains the plasma flows up and down the plume field lines and leads to the shape of the neon line in PCHs.

  12. Effects of electrical noise to a knee joint on quiet bipedal stance and treadmill walking.

    PubMed

    Kimura, T; Taki, C; Shiozawa, N; Kouzaki, M

    2013-01-01

    The present study assessed whether an unperceivable, noise-like electrical stimulation of a knee joint enhances the stability of quiet bipedal stance and treadmill walking in young subjects. The results showed that the slow postural sway measures in quiet bipedal stance were significantly reduced by the electrical noise (P<0.05). In the treadmill walking, low frequency component (below 1 Hz) of mediolateral acceleration, measured at the third lumbar vertebra, significantly decreased with the electrical noise (P<0.05), while there were no changes in the anteroposterior and vertical directions. These results indicate that the electrical noise to a knee joint can be applied to enhance postural control in quiet bipedal stance and treadmill walking. PMID:24110917

  13. Covering factors of the dusty obscurers in radio-loud and radio-quiet quasars

    NASA Astrophysics Data System (ADS)

    Gupta, Maitrayee; Sikora, Marek; Nalewajko, Krzysztof

    2016-09-01

    We compare covering factors of circumnuclear dusty obscurers in radio-loud and radio-quiet quasars. The radio-loud quasars are represented by a sample of FR II quasars obtained by cross-matching a catalog of the FR II radio sources selected by van Velzen et al. with the SDSS DR7 catalog of quasars. Covering factors of FR II quasars are compared with covering factors of the radio-quiet quasars matched with them in redshift, black hole mass, and Eddington-ratio. We found that covering factors, proxied by the infrared-to-bolometric luminosity ratio, are on average slightly smaller in FR II quasars than in radio-quiet quasars, however, this difference is statistically significant only for the highest Eddington ratios. For both samples, no statistically significant dependence of a median covering factor on Eddington ratio, black hole mass, nor redshift can be claimed.

  14. A quiet flow Ludwieg tube for study of transition in compressible boundary layers: Design and feasibility

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1991-01-01

    Laminar-turbulent transition in high speed boundary layers is a complicated problem which is still poorly understood, partly because of experimental ambiguities caused by operating in noisy wind tunnels. The NASA Langley experience with quiet tunnel design has been used to design a quiet flow tunnel which can be constructed less expensively. Fabrication techniques have been investigated, and inviscid, boundary layer, and stability computer codes have been adapted for use in the nozzle design. Construction of such a facility seems feasible, at a reasonable cost. Two facilities have been proposed: a large one, with a quiet flow region large enough to study the end of transition, and a smaller and less expensive one, capable of studying low Reynolds number issues such as receptivity. Funding for either facility remains to be obtained, although key facility elements have been obtained and are being integrated into the existing Purdue supersonic facilities.

  15. A quiet-flow Ludwieg tube for experimental study of high speed boundary layer transition

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1991-01-01

    Laminar-turbulent transition in high speed boundary layers is a complicated problem which is still poorly understood, partly because of experimental ambiguities caused by operating in noisy wind tunnels. The NASA Langley experience with quiet tunnel design has been used to design a quiet flow tunnel which can be constructed less expensively. Fabrication techniques have been investigated, and inviscid, boundary layer, and stability computer codes have been adapted for use in the nozzle design. Construction of such a facility seems feasible, at a reasonable cost. Two facilities have been proposed: a large one, with a quiet flow region large enough to study the end of transition, and a smaller and less expensive one, capable of studying low Reynolds number issues such as receptivity. Funding for either facility remains to be obtained, although key facility elements have been obtained and are being integrated into the existing Purdue supersonic facilities.

  16. A description of the external and internal quiet daily variation currents at North American locations for a quiet-Sun year.

    USGS Publications Warehouse

    Campbell, W.H.

    1983-01-01

    An order 4, degree 12 spherical harmonic analysis of the smoothed quiet geomagnetic daily variations was used to separate the external and internal geomagnetic Sq field at North American locations for the quiet-Sun year, 1965. These fields were represented by a month-by-month display of equivalent current vortex systems with dominant, pre-noon foci. The focus reached 40o latitude near the June solstice and about 30o latitude near the December solstice. The daily range of Sq current amplitudes was largest in late July to early August and smallest in mid-December. Semi-annual variations of Sq currents dominated only the equatorial region. Daily maxima in mid-latitudes, occurred mostly near local noon in December to February and about 1 hr before noon in June to mid-October. -Author

  17. Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen D.

    1991-01-01

    The main objectives of this work is to demonstrate the potential of a cryogenic adaptive nozzle to generate quiet (low disturbance) supersonic flow. A drive system was researched for the Fluid Mechanics Laboratory (FML) Laminar Flow Supersonic Wind Tunnel (LFSWT) using a pilot tunnel. A supportive effort for ongoing Proof of Concept (PoC) research leading to the design of critical components of the LFSWT was maintained. The state-of-the-art in quiet supersonic wind tunnel design was investigated. A supersonic research capability was developed within the FML.

  18. A Review of Hypersonic Boundary Layer Stability Experiments in a Quiet Mach 6 Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Wilkinson, Stephen P.

    1997-01-01

    Three recent experimental studies of transition on cones with adverse pressure gradient produced by a flared afterbody and with the additive stability modifiers of wall cooling, angle of attack and bluntness are reviewed. All tests were conducted in a quiet Mach 6 wind tunnel. The dominant instability was found to be the second mode. For the cases examined with linear stability theory, the N factors at mode saturation were in the range of 8.5 to 11. Evidence of a combined second-mode/Gortler transition process was found. Mean, rms and spectral freestream data for the quiet facility is presented and the role of low frequency freestream noise is discussed.

  19. Operational evaluation of a proppeller test stand in the quiet flow facility at Langley Research Center

    NASA Technical Reports Server (NTRS)

    Block, P. J. W.

    1982-01-01

    Operational proof tests of a propeller test stand (PTS) in a quiet flow facility (QFF) are presented. The PTS is an experimental test bed for acoustic propeller research in the quiet flow environment of the QFF. These proof tests validate thrust and torque predictions, examine the repeatability of measurements on the PTS, and determine the effect of applying artificial roughness to the propeller blades. Since a thrusting propeller causes an open jet to contract, the potential flow core was surveyed to examine the magnitude of the contraction. These measurements are compared with predicted values. The predictions are used to determine operational limitations for testing a given propeller design in the QFF.

  20. Combined X-Ray and mm-Wave Observations of Radio Quiet Active Galaxies

    NASA Astrophysics Data System (ADS)

    Behar, E.

    2016-06-01

    A connection between the X-ray and radio sources in radio quiet active galaxies (AGNs) will be demonstrated. High radio frequency, i.e., mm-wave observations are promising probes of the X-ray emitting inner regions of the accretion disks in radio quiet AGNs. An argument for simultaneous observations in X-rays and in mm waves will be made, in order to promote these as one of the future science goals of X-ray and AGN astronomy in the next decade. Preliminary results from an exploratory campaign with several space and ground based telescopes will be presented.

  1. Nonuniversal gaugino and scalar masses, hadronically quiet trileptons, and the Large Hadron Collider

    SciTech Connect

    Bhattacharya, Subhaditya; Datta, AseshKrishna; Mukhopadhyaya, Biswarup

    2008-12-01

    We investigate the parameter space of the minimal supersymmetric standard model where the gluino and squark masses are much above 1 TeV but the remaining part of the sparticle spectrum is accessible to the Large Hadron Collider at CERN. After pointing out that such a scenario may constitute an important benchmark of gaugino/scalar nonuniversality, we find that hadronically quiet trileptons are rather useful signals for it. Regions of the parameter space, where the signal is likely to be appreciable, are identified through a detailed scan. The advantage of hadronically quiet trileptons over other types of signals is demonstrated.

  2. A quiet flow Ludwieg tube for study of transition in compressible boundary layers: Design and feasibility

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1990-01-01

    Since Ludwieg tubes have been around for many years, and NASA has already established the feasibility of creating quiet-flow wind tunnels, the major question addressed was the cost of the proposed facility. Cost estimates were obtained for major system components, and new designs which allowed fabrication at lower cost were developed. A large fraction of the facility cost comes from the fabrication of the highly polished quiet-flow supersonic nozzle. Methods for the design of this nozzle were studied at length in an attempt to find an effective but less expensive design. Progress was sufficient to show that a quality facility can be fabricated at a reasonable cost.

  3. Change of solar wind quasi-invariant in solar cycle 23—Analysis of PDFs

    NASA Astrophysics Data System (ADS)

    Leitner, M.; Farrugia, C. J.; Vörös, Z.

    2011-02-01

    An in situ solar wind measurement which is a very good proxy for solar activity, correlating well with the sunspot number, is the solar wind “quasi-invariant” (QI), which is defined as the ratio between magnetic and kinetic energy densities. Here we use 1-min OMNI data to determine yearly probability density functions (PDFs) for QI. We distinguish between fast and slow solar winds, and exclude interplanetary coronal mass ejections (ICMEs) from the data, since the latter have a different distribution. Fitting the PDFs by a log-kappa distribution, we discuss the variation of QI in the period 1995-2009, encompassing solar cycle 23 and the long, very quiet minimum in 2007-2009. The additional value of kappa allows us to obtain a better description for the tails of the distribution than the log-normal approach. Here we describe for the first time how parameter kappa changes over one solar cycle.

  4. The evolution of magnetic network elements in the quiet Sun

    NASA Technical Reports Server (NTRS)

    Liu, Y.; Zhang, H.; Ai, G.; Wang, H.; Zirin, H.

    1994-01-01

    Using the 155-h coordinated magnetograph data of Huairou and Big Bear Solar Observatories, we have studied the evolution and lifetime of magnetic network elements in an enhanced network region. Both statistical and counting methods give a mean lifetime of network elements of 50h. The network elements are divided into two categories according to their evolution: 'breakup' and 'merging'. They have similar average lifetimes. We also find that the number of the elements that disappear by merging is about twice that by breakup. This may indicate that the creation and disappearance of magnetic network elements are balanced.

  5. Solar flares controlled by helicity conservation

    NASA Technical Reports Server (NTRS)

    Gliner, Erast B.; Osherovich, Vladimir A.

    1995-01-01

    The energy release in a class of solar flares is studied on the assumption that during burst events in highly conducting plasma the magnetic helicity of plasma is approximately conserved. The available energy release under a solar flare controlled by the helicity conservation is shown to be defined by the magnetic structure of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominences; the discontinuation of the reconnection of magnetic lines long before the complete reconnection of participated fields occurs; the existence of quiet prominences which, in spite of their usual optical appearance, do not initiate any flare events; the small energy release under a solar flare in comparison with the stockpile of magnetic energy in surrounding fields. The predicted scale of the energy release is in a fair agreement with observations.

  6. Observation and Modeling of the Solar Transition Region. 1; Multi-Spectral Solar Telescope Array Observations

    NASA Technical Reports Server (NTRS)

    Oluseyi, Hakeem M.; Walker, A. B. C., II; Porter, Jason; Hoover, Richard B.; Barbee, Troy W., Jr.

    1999-01-01

    We report on observations of the solar atmosphere in several extreme-ultraviolet and far-ultraviolet bandpasses obtained by the Multi-Spectral Solar Telescope Array, a rocket-borne spectroheliograph, on flights in 1987, 1991, and 1994, spanning the last solar maximum. Quiet-Sun emission observed in the 171-175 Angstrom bandpass, which includes lines of O v, O VI, Fe IX, and Fe X, has been analyzed to test models of the temperatures and geometries of the structures responsible for this emission. Analyses of intensity variations above the solar limb reveal scale heights consistent with a quiet-Sun plasma temperature of 500,000 less than or equal to T (sub e) less than or equal to 800,000 K. The structures responsible for the quiet-Sun EUV emission are modeled as small quasi-static loops. We submit our models to several tests. We compare the emission our models would produce in the bandpass of our telescope to the emission we have observed. We find that the emission predicted by loop models with maximum temperatures between 700,000 and 900,000 K are consistent with our observations. We also compare the absolute flux predicted by our models in a typical upper transition region line to the flux measured by previous observers. Finally, we present a preliminary comparison of the predictions of our models with diagnostic spectral line ratios from previous observers. Intensity modulations in the quiet Sun are observed to occur on a scale comparable to the supergranular scale. We discuss the implications that a distribution of loops of the type we model here would have for heating the local network at the loops' footpoints.

  7. Solar Wind Strahl Broadening by Self-Generated Plasma Waves

    NASA Technical Reports Server (NTRS)

    Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.

    2013-01-01

    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.

  8. VizieR Online Data Catalog: UV spectrum of the quiet Sun above the limb (Warren+, 2014)

    NASA Astrophysics Data System (ADS)

    Warren, H. P.; Ugarte-Urra, I.; Landi, E.

    2014-09-01

    First, we compare full-disk mosaics constructed by scanning the EIS slot over the Sun with irradiance observations made by the EUV Variability Experiment (EVE; Woods et al. 2012SoPh..275..115W) on the Solar Dynamics Observatory (SDO) mission. These comparisons provide a means of establishing the absolute calibration for EIS. Second, we combine extended EIS observations from above the limb in the quiet Sun with a simple temperature model to simultaneously determine the differential emission measure (DEM) distribution and the time-dependent changes to the effective areas that best fit all of the available spectral lines. In Figure 2 we show the average spectrum from an observation of seven consecutive runs of ELFULLCCDWSUMER. The observations began on 2007 November 4 19:12 and ended on the same date at 23:51 UT. The EIS field of view was centered at (990", -50") about 22" above the limb of the Sun. The central 129 pixels along the slit have been averaged over 38 exposures (11 exposures were corrupted in transmission to the ground) for a total of 4902 intensity measurements at each wavelength. Since each exposure is 300s, the spectrum represents 1470600 pixels of effective exposure time and allows weak lines at the ends of the detector to be measured. (1 data file).

  9. Search for characteristic features of low-energy quiet-time H, He and heavy nuclei fluxes, 1973-1977

    NASA Technical Reports Server (NTRS)

    Mason, G. M.; Gloeckler, G.; Hovestadt, D.

    1980-01-01

    Results of a survey of the 0.5-10 MeV/nucleon fluxes of H, He and heavier ions during interplanetary 'quiet-times' over the period 1973-1977 using the ULET telescope on IMP-8 are reported. It is found that in this energy range no characteristic flux level, or, e.g., proton/alpha ratio emerges during quiet periods in any year, thus precluding systematic long-term studies of the time behavior of the quiet-time component at these energies. Spectra for a uniquely quiet period in May 1977 and a less restrictively chosen set of quiet periods in 1976-1977 are presented and compared with previous results.

  10. Laboratory studies in ultraviolet solar physics

    NASA Technical Reports Server (NTRS)

    Parkinson, W. H.; Kohl, J. L.; Gardner, L. D.; Raymond, J. C.; Smith, P. L.

    1991-01-01

    The research activity comprised the measurement of basic atomic processes and parameters which relate directly to the interpretation of solar ultraviolet observations and to the development of comprehensive models of the component structures of the solar atmosphere. The research was specifically directed towards providing the relevant atomic data needed to perform and to improve solar diagnostic techniques which probe active and quiet portions of the solar chromosphere, the transition zone, the inner corona, and the solar wind acceleration regions of the extended corona. The accuracy with which the physical conditions in these structures can be determined depends directly on the accuracy and completeness of the atomic and molecular data. These laboratory data are used to support the analysis programs of past and current solar observations (e.g., the Orbiting solar Observatories, the Solar Maximum Mission, the Skylab Apollo Telescope Mount, and the Naval Research Laboratory's rocket-borne High Resolution Telescope and Spectrograph). In addition, we attempted to anticipate the needs of future space-borne solar studies such as from the joint ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Our laboratory activities stressed two categories of study: (1) the measurement of absolute rate coefficients for dielectronic recombination and electron impact excitation; and (2) the measurement of atomic transition probabilities for solar density diagnostics. A brief summary of the research activity is provided.

  11. Confronting the Quiet Crisis: How Chief State School Officers Are Advancing Quality Early Childhood Opportunities

    ERIC Educational Resources Information Center

    Council of Chief State School Officers, 2012

    2012-01-01

    In 2009, the Council of Chief State School Officers (CCSSO) adopted a new policy statement on early childhood education. Based on the work of a task force of 13 chiefs, "A Quiet Crisis: The Urgent Need to Build Early Childhood Systems and Quality Programs for Children Birth to Age Five" presents a compelling argument for why public education…

  12. Effects of road traffic noise and the benefit of access to quietness

    NASA Astrophysics Data System (ADS)

    Öhrström, E.; Skånberg, A.; Svensson, H.; Gidlöf-Gunnarsson, A.

    2006-08-01

    Socio-acoustic surveys were carried out as part of the Soundscape Support to Health research programme to assess the health effects of various soundscapes in residential areas. The study was designed to test whether having access to a quiet side of one's dwelling enhances opportunities for relaxation and reduces noise annoyance and other adverse health effects related to noise. The dwellings chosen were exposed to sound levels from road traffic ranging from about L=45-68 dB at the most-exposed side. The study involved 956 individuals aged 18-75 years. The results demonstrate that access to quiet indoor and outdoor sections of one's dwelling supports health; it produces a lower degree and extent of annoyance and disturbed daytime relaxation, improves sleep and contributes to physiological and psychological well-being. Having access to a quiet side of one's dwelling reduces disturbances by an average of 30-50% for the various critical effects, and corresponds to a reduction in sound levels of ( LAeq,24h) 5 dB at the most-exposed side. To protect most people (80%) from annoyance and other adverse effects, sound levels from road traffic should not exceed ( LAeq,24h) 60 dB at the most-exposed side, even if there is access to a quiet side of one's dwelling ( LAeq,24h⩽45 dB).

  13. The Effects of Active and Quiet Activities Upon Subsequent Attending of Preschool Children.

    ERIC Educational Resources Information Center

    Hawn, Joyce; And Others

    The present study examined the effect of preceding activities upon the attending behavior of preschool children while listening to a story in a large group situation. Attending in the group subsequent to active play was compared with attending in the group subsequent to a quiet activity. The four subjects of this research ranged in age from 3 to 4…

  14. The Epistemology of Mathematical and Statistical Modeling: A Quiet Methodological Revolution

    ERIC Educational Resources Information Center

    Rodgers, Joseph Lee

    2010-01-01

    A quiet methodological revolution, a modeling revolution, has occurred over the past several decades, almost without discussion. In contrast, the 20th century ended with contentious argument over the utility of null hypothesis significance testing (NHST). The NHST controversy may have been at least partially irrelevant, because in certain ways the…

  15. Quiet Eye Duration Is Responsive to Variability of Practice and to the Axis of Target Changes

    ERIC Educational Resources Information Center

    Horn, Robert R.; Okumura, Michelle S.; Alexander, Melissa G. F.; Gardin, Fredrick A.; Sylvester, Curtis T.

    2012-01-01

    We tested the hypothesis that quiet eye, the final fixation before the initiation of a movement in aiming tasks, is used to scale the movement's parameters. Two groups of 12 participants (N = 24) threw darts to targets in the horizontal and vertical axes under conditions of higher (random) or lower (blocked) target variability. Supporting our…

  16. Quiet Clean Short-Haul Experimental Engine (QSCEE). Preliminary analyses and design report, volume 1

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The experimental propulsion systems to be built and tested in the 'quiet, clean, short-haul experimental engine' program are presented. The flight propulsion systems are also presented. The following areas are discussed: acoustic design; emissions control; engine cycle and performance; fan aerodynamic design; variable-pitch actuation systems; fan rotor mechanical design; fan frame mechanical design; and reduction gear design.

  17. Boundary-Layer Instability Measurements in a Mach-6 Quiet Tunnel

    NASA Technical Reports Server (NTRS)

    Berridge, Dennis C.; Ward, Christopher, A. C.; Luersen, Ryan P. K.; Chou, Amanda; Abney, Andrew D.; Schneider, Steven P.

    2012-01-01

    Several experiments have been performed in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue University. A 7 degree half angle cone at 6 degree angle of attack with temperature-sensitive paint (TSP) and PCB pressure transducers was tested under quiet flow. The stationary crossflow vortices appear to break down to turbulence near the lee ray for sufficiently high Reynolds numbers. Attempts to use roughness elements to control the spacing of hot streaks on a flared cone in quiet flow did not succeed. Roughness was observed to damp the second-mode waves in areas influenced by the roughness, and wide roughness spacing allowed hot streaks to form between the roughness elements. A forward-facing cavity was used for proof-of-concept studies for a laser perturber. The lowest density at which the freestream laser perturbations could be detected was 1.07 x 10(exp -2) kilograms per cubic meter. Experiments were conducted to determine the transition characteristics of a streamwise corner flow at hypersonic velocities. Quiet flow resulted in a delayed onset of hot streak spreading. Under low Reynolds number flow hot streak spreading did not occur along the model. A new shock tube has been built at Purdue. The shock tube is designed to create weak shocks suitable for calibrating sensors, particularly PCB-132 sensors. PCB-132 measurements in another shock tube show the shock response and a linear calibration over a moderate pressure range.

  18. White dwarf models for type 1 supernovae and quiet supernovae, and presupernova evolution

    NASA Technical Reports Server (NTRS)

    Nomoto, K.

    1980-01-01

    Supernova mechanisms in accreting white dwarfs are considered with emphasis on deflagration as a plausible mechanism for producing Type I supernovae and electron captures to form quiet supernovae leaving neutron stars. These outcomes depend on accretion rate of helium, initial mass and composition of the white dwarf. The various types of hydrogen shell burning in the presupernova stage are also discussed.

  19. Of Chickens, Eggs, and Expertise: Observations Complimentary and Contrary to "The Quiet Evolution."

    ERIC Educational Resources Information Center

    Lankford, E. Louis

    1999-01-01

    Responds to Brent Wilson's report "The Quiet Evolution: Changing the Face of Arts Education," focusing on how Wilson centers the curriculum around key works of art. Explains that ideas, issues, and themes should be central instead and addresses the development of teacher expertise. (CMK)

  20. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Pt... carry a degree of uncertainty about the quiet zone's continued existence. (3) The use of the first or... methods (first and fourth scenarios), the public authority will never need to be concerned about...

  1. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Pt... carry a degree of uncertainty about the quiet zone's continued existence. (3) The use of the first or... methods (first and fourth scenarios), the public authority will never need to be concerned about...

  2. Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.

    1995-01-01

    Low-disturbance or 'quiet' wind tunnels are now considered an essential part of meaningful boundary layer transition research. Advances in Supersonic Laminar Flow Control (SLFC) technology for swept wings depends on a better understanding of the receptivity of the transition phenomena to attachment-line contamination and cross-flows. This need has provided the impetus for building the Laminar Flow Supersonic Wind Tunnel (LFSWT) at NASA-Ames, as part of the NASA High Speed Research Program (HSRP). The LFSWT was designed to provide NASA with an unequaled capability for transition research at low supersonic Mach numbers (<2.5). The following are the objectives in support of the new Fluid Mechanic Laboratory (FML) quiet supersonic wind tunnel: (I) Develop a unique injector drive system using the existing FML indraft compressor; (2) Develop an FML instrumentation capability for quiet supersonic wind tunnel evaluation and transition studies at NASA-Ames; (3) Determine the State of the Art in quiet supersonic wind tunnel design; (4) Build and commission the LFSWT; (5) Make detailed flow quality measurements in the LFSWT; (6) Perform tests of swept wing models in the LFSWT in support of the NASA HSR program; and (7) Provide documentation of research progress.

  3. Brief quiet ego contemplation reduces oxidative stress and mind-wandering

    PubMed Central

    Wayment, Heidi A.; Collier, Ann F.; Birkett, Melissa; Traustadóttir, Tinna; Till, Robert E.

    2015-01-01

    Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student’s compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32) in their first semester of college who reported greater self-protective (e.g., defensive) goals in the first 2 weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC), QEC with virtual reality (VR) headset (QEC-VR), and control. Participants came to the lab three times to engage in a 15-min exercise in a 30-days period. The 15-min QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives. PMID:26483734

  4. Organization of Functional Postural Responses Following Perturbations in Multiple Directions in Elderly Fallers Standing Quietly

    ERIC Educational Resources Information Center

    Matjacic, Zlatko; Sok, David; Jakovljevic, Miroljub; Cikajlo, Imre

    2013-01-01

    The objective of the study was to assess functional postural responses by analyzing the center-of-pressure trajectories resulting from perturbations delivered in multiple directions to elderly fallers. Ten elderly individuals were standing quietly on two force platforms while an apparatus delivered controlled perturbations at the level of pelvis…

  5. Behavioral effect of knee joint motion on body's center of mass during human quiet standing.

    PubMed

    Yamamoto, Akio; Sasagawa, Shun; Oba, Naoko; Nakazawa, Kimitaka

    2015-01-01

    The balance control mechanism during upright standing has often been investigated using single- or double-link inverted pendulum models, involving the ankle joint only or both the ankle and hip joints, respectively. Several studies, however, have reported that knee joint motion during quiet standing cannot be ignored. This study aimed to investigate the degree to which knee joint motion contributes to the center of mass (COM) kinematics during quiet standing. Eight healthy adults were asked to stand quietly for 30s on a force platform. Angular displacements and accelerations of the ankle, knee, and hip joints were calculated from kinematic data obtained by a motion capture system. We found that the amplitude of the angular acceleration was smallest in the ankle joint and largest in the hip joint (ankle < knee < hip). These angular accelerations were then substituted into three biomechanical models with or without the knee joint to estimate COM acceleration in the anterior-posterior direction. Although the "without-knee" models greatly overestimated the COM acceleration, the COM acceleration estimated by the "with-knee" model was similar to the actual acceleration obtained from force platform measurement. These results indicate substantial effects of knee joint motion on the COM kinematics during quiet standing. We suggest that investigations based on the multi-joint model, including the knee joint, are required to reveal the physiologically plausible balance control mechanism implemented by the central nervous system. PMID:25248799

  6. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Guide to Establishing Quiet Zones C Appendix C to Part 222 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Pt. 222, App. C Appendix C to Part...

  7. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Guide to Establishing Quiet Zones C Appendix C to Part 222 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Pt. 222, App. C Appendix C to Part...

  8. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false What are the minimum requirements for quiet zones? 222.35 Section 222.35 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of...

  9. Climatology and IMF By dependence of quiet-time high-latitude upper thermospheric winds measured by ground-based Fabry-Perot Interferometers in the northern and southern hemispheres

    NASA Astrophysics Data System (ADS)

    Emmert, J. T.; Hernandez, G.; Jarvis, M. J.; Niciejewski, R. J.; Sipler, D. P.; Vennerstrom, S.

    2006-05-01

    We analyze ground-based Fabry-Perot interferometer observations, obtained from the CEDAR database, of upper thermospheric (~250 km) horizontal winds derived from Doppler shifts in the 630.0 nm (red line) nightglow. The winds were measured over the following locations: South Pole (90S), Halley (76S, 27W), Millstone Hill (43N, 72W), Sondre Stromfjord (67N, 51W), and Thule (77N, 68W). We derive climatological quiet-time (Kp < 3) wind patterns as a function of local time, solar cycle, day-of-year, and the y-component of the interplanetary magnetic field (IMF By). In magnetic coordinates, the quiet-time high latitude wind patterns are dominated by anti-sunward flow over the polar cap, with wind speeds that generally increase with increasing solar EUV irradiation. Within the limited seasonal coverage afforded by the nighttime (mostly winter) data, the day-of-year dependence is generally weak. IMF By exerts a strong influence on the wind patterns, particularly in the midnight sector. During winter, positive-By winds around midnight in the northern (southern) hemisphere are directed more toward the dusk (dawn) sector, compared to corresponding negative-By winds; this behavior is consistent with the By-dependence of statistical ionospheric convection patterns The strength of the wind response to IMF By tends to increase with increasing solar EUV irradiation, roughly in proportion to the increased wind speeds. Quiet-time IMF By effects are detectable at latitudes as low as that of Millstone Hill (magnetic latitude 53N).

  10. Solar cycle variation of the statistical distribution of the solar wind ɛ parameter and its constituent variables

    NASA Astrophysics Data System (ADS)

    Tindale, E.; Chapman, S. C.

    2016-06-01

    We use 20 years of Wind solar wind observations to investigate the solar cycle variation of the solar wind driving of the magnetosphere. For the first time, we use generalized quantile-quantile plots to compare the statistical distribution of four commonly used solar wind coupling parameters, Poynting flux, B2, the ɛ parameter, and vB, between the maxima and minima of solar cycles 23 and 24. We find the distribution is multicomponent and has the same functional form at all solar cycle phases; the change in distribution is captured by a simple transformation of variables for each component. The ɛ parameter is less sensitive than its constituent variables to changes in the distribution of extreme values between successive solar maxima. The quiet minimum of cycle 23 manifests only in lower extreme values, while cycle 24 was less active across the full distribution range.

  11. Observation of Quiet Limb in He I 1083.0 nm, H Paschen alpha1281.8 nm and H Brackett gamma 2166.1 nm lines

    NASA Astrophysics Data System (ADS)

    Prasad Choudhary, Debi

    2016-05-01

    In this paper, we shall present the results of an observational study of the quiet solar limb in the near infrared lines using the New IR Array Camera (NAC) and the vertical spectrograph at the focal plane of McMath-Pierce telescope. The NAC, at the exit port of the spectrograph, was used to record the limb spectrum in HeI 1083.0 nm, Hydrogen Paschen 1281.8 nm and Brackett 2165.5 nm wavelength regions. The NAC is a 1024x1024 InSb Alladin III Detector operating over 1-5 micron range with high density sampling at 0.018 arc second/pixel. The all-reflective optical train minimizes number of surfaces and eliminates ghosts leading to low scatter, ghost-free optics. The close-cycle cryogenic provides a stable cooling environment over six hour period with an accuracy of 0.01K leading to low dark current. The low read out noise combined with low scattered light and dark current makes NAC an ideal detector for making high quality infrared spectral observations of solar limb. The limb spectrums were obtained by placing the spectrograph slit perpendicular to the limb at an interval of 10 degrees around the solar disk. We shall report the intensity profile, line-of-sight velocity and line width distribution around the sun derived from the spectra along the slit.

  12. Scale-free texture of the fast solar wind.

    PubMed

    Hnat, B; Chapman, S C; Gogoberidze, G; Wicks, R T

    2011-12-01

    The higher-order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically, scale by scale. We find a single global non-Gaussian scale-free behavior from minutes to over 5 h. This spans the signature of an inertial range of magnetohydrodynamic turbulence and a ~1/f range in magnetic field components. This global scaling in field magnitude fluctuations is an intrinsic component of the underlying texture of the solar wind and puts a strong constraint on any theory of solar corona and the heliosphere. Intriguingly, the magnetic field and velocity components show scale-dependent dynamic alignment outside of the inertial range. PMID:22304144

  13. Suprathermal Tails in the Solar Wind and at Interplanetary Discontinuities

    NASA Astrophysics Data System (ADS)

    Kucharek, H.; Popecki, M.; Farrugia, C. J.; Galvin, A. B.; Klecker, B.

    2014-12-01

    Ion mass spectrometers on several spacecraft have identified suprathermal tails on the velocity distributions of solar wind and pickup ions as a common feature. These tail distributions typically show a power law with a rollover at higher energies. The power law behavior of these suprathermal tails has been studied during so-called quiet times of the solar wind (no significant wave activity) as well as during active periods of the solar cycle. Several studies reported different results for this power law index, ranging from -9 to -1. In this study we used data from the PLASTIC and IMPACT instruments on STEREO spacecraft A in 2008 during a pronounced solar minimum. We investigate the temporal and spatial evolution of these tails at interplanetary structures such as shocks, stream interfaces, magnetic clouds, Alfvénic turbulence, and quiet times. We focus on He+ data to investigate ion acceleration, the formation of suprathermal tails and their association with Alfvénic turbulence. The results of this study show that in shocks and stream interfaces, the spectral index varies dramatically in space and time. Both pre-existing energetic ion populations as well as elevated Alfvénic turbulence impact the spectral slope. Quiet times, which may represent thermalized plasma, tend to show spectral slopes which are closer to -5.

  14. Solar astronomy

    NASA Technical Reports Server (NTRS)

    Rosner, Robert; Noyes, Robert; Antiochos, Spiro K.; Canfield, Richard C.; Chupp, Edward L.; Deming, Drake; Doschek, George A.; Dulk, George A.; Foukal, Peter V.; Gilliland, Ronald L.

    1991-01-01

    An overview is given of modern solar physics. Topics covered include the solar interior, the solar surface, the solar atmosphere, the Large Earth-based Solar Telescope (LEST), the Orbiting Solar Laboratory, the High Energy Solar Physics mission, the Space Exploration Initiative, solar-terrestrial physics, and adaptive optics. Policy and related programmatic recommendations are given for university research and education, facilitating solar research, and integrated support for solar research.

  15. Imaging the host galaxies of high-redshift radio-quiet QSOs

    NASA Technical Reports Server (NTRS)

    Lowenthal, James D.; Heckman, Timothy M.; Lehnert, Matthew, D.; Elias, J. H.

    1995-01-01

    We present new deep K-band and optical images of four radio-quiet QSOs at z approximately = 1 and six radio-quiet QSOs at z approximately = 2.5, as well as optical images only of six more at z approximately = 2.5. We have examined the images carefully for evidence of extended 'fuzz' from any putative QSO host galaxy. None of the z approximately = 2.5 QSOs shows any extended emission, and only two of the z approximately = 1 QSOs show marginal evidence for extended emission. Our 3 sigma detection limits in the K images, m(sub K) approximately = 21 for an isolated source, would correspond approximately to an unevolved L(sup star) elliptical galaxy at z = 2.5 or 2-3 mag fainter than an L(sup star) elliptical at z = 1, although our limits on host galaxy light are weaker than this due to the difficulty of separating galaxy light from QSO light. We simulate simple models of disk and elliptical host galaxies, and find that the marginal emission around the two z approximately = 1 QSOs can be explained by disks or bulges that are approximately 1-2 mag brighter than an unevolved L(sup star) galaxy in one case and approximately 1.5-2.5 mag brighter than L(sub star) in the other. For two other z approximately = 1 QSOs, we have only upper limits (L approximately = L(sup star)). The hosts of the high-redshift sample must be no brighter than about 3 mag above an unevolved L(sup star) galaxy, and are at least 1 magnitude fainter than the hosts of radio-loud QSOs at the same redshift. If the easily detected K-band light surrounding a previous sample of otherwise similar but radio-loud QSOs is starlight, then it must evolve on timescales of greater than or approximately equal to 10(exp 8) yr (e.g., Chambers & Charlot 1990); therefore our non-detection of host galaxy fuzz around radio-quiet QSOs supports the view that high-redshift radio-quiet and radio-loud QSOs inhabit different host objects, rather than being single types of objects that turn their radio emission on and off over

  16. The quiet Sun magnetic field observed with ZIMPOL on THEMIS. I. The probability density function

    NASA Astrophysics Data System (ADS)

    Bommier, V.; Martínez González, M.; Bianda, M.; Frisch, H.; Asensio Ramos, A.; Gelly, B.; Landi Degl'Innocenti, E.

    2009-11-01

    Context: The quiet Sun magnetic field probability density function (PDF) remains poorly known. Modeling this field also introduces a magnetic filling factor that is also poorly known. With these two quantities, PDF and filling factor, the statistical description of the quiet Sun magnetic field is complex and needs to be clarified. Aims: In the present paper, we propose a procedure that combines direct determinations and inversion results to derive the magnetic field vector and filling factor, and their PDFs. Methods: We used spectro-polarimetric observations taken with the ZIMPOL polarimeter mounted on the THEMIS telescope. The target was a quiet region at disk center. We analyzed the data by means of the UNNOFIT inversion code, with which we inferred the distribution of the mean magnetic field α B, α being the magnetic filling factor. The distribution of α was derived by an independent method, directly from the spectro-polarimetric data. The magnetic field PDF p(B) could then be inferred. By introducing a joint PDF for the filling factor and the magnetic field strength, we have clarified the definition of the PDF of the quiet Sun magnetic field when the latter is assumed not to be volume-filling. Results: The most frequent local average magnetic field strength is found to be 13 G. We find that the magnetic filling factor is related to the magnetic field strength by the simple law α = B_1/B with B1 = 15 G. This result is compatible with the Hanle weak-field determinations, as well as with the stronger field determinations from the Zeeman effect (kGauss field filling 1-2% of space). From linear fits, we obtain the analytical dependence of the magnetic field PDF. Our analysis has also revealed that the magnetic field in the quiet Sun is isotropically distributed in direction. Conclusions: We conclude that the quiet Sun is a complex medium where magnetic fields having different field strengths and filling factors coexist. Further observations with a better

  17. Solar Activity Predictions Based on Solar Dynamo Theories

    NASA Astrophysics Data System (ADS)

    Schatten, Kenneth H.

    2009-05-01

    We review solar activity prediction methods, statistical, precursor, and recently the Dikpati and the Choudhury groups’ use of numerical flux-dynamo methods. Outlining various methods, we compare precursor techniques with weather forecasting. Precursors involve events prior to a solar cycle. First started by the Russian geomagnetician Ohl, and then Brown and Williams; the Earth's field variations near solar minimum was used to predict the next solar cycle, with a correlation of 0.95. From the standpoint of causality, as well as energetically, these relationships were somewhat bizarre. One index used was the "number of anomalous quiet days,” an antiquated, subjective index. Scientific progress cannot be made without some suspension of disbelief; otherwise old paradigms become tautologies. So, with youthful naïveté, Svalgaard, Scherrer, Wilcox and I viewed the results through rose-colored glasses and pressed ahead searching for understanding. We eventually fumbled our way to explaining how the Sun could broadcast the state of its internal dynamo to Earth. We noted one key aspect of the Babcock-Leighton Flux Dynamo theory: the polar field at the end of a cycle serves as a seed for the next cycle's growth. Near solar minimum this field usually bathes the Earth, and thereby affects geomagnetic indices then. We found support by examining 8 previous solar cycles. Using our solar precursor technique we successfully predicted cycles 21, 22 and 23 using WSO and MWSO data. Pesnell and I improved the method using a SODA (SOlar Dynamo Amplitude) Index. In 2005, nearing cycle 23's minimum, Svalgaard and I noted an unusually weak polar field, and forecasted a small cycle 24. We discuss future advances: the flux-dynamo methods. As far as future solar activity, I shall let the Sun decide; it will do so anyhow.

  18. Solar astrophysical fundamental parameters

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Irbah, A.; Hauchecorne, A.

    2014-08-01

    The accurate determination of the solar photospheric radius has been an important problem in astronomy for many centuries. From the measurements made by the PICARD spacecraft during the transit of Venus in 2012, we obtained a solar radius of 696,156±145 kilometres. This value is consistent with recent measurements carried out atmosphere. This observation leads us to propose a change of the canonical value obtained by Arthur Auwers in 1891. An accurate value for total solar irradiance (TSI) is crucial for the Sun-Earth connection, and represents another solar astrophysical fundamental parameter. Based on measurements collected from different space instruments over the past 35 years, the absolute value of the TSI, representative of a quiet Sun, has gradually decreased from 1,371W.m-2 in 1978 to around 1,362W.m-2 in 2013, mainly due to the radiometers calibration differences. Based on the PICARD data and in agreement with Total Irradiance Monitor measurements, we predicted the TSI input at the top of the Earth's atmosphere at a distance of one astronomical unit (149,597,870 kilometres) from the Sun to be 1,362±2.4W.m-2, which may be proposed as a reference value. To conclude, from the measurements made by the PICARD spacecraft, we obtained a solar photospheric equator-to-pole radius difference value of 5.9±0.5 kilometres. This value is consistent with measurements made by different space instruments, and can be given as a reference value.

  19. Helioseismology with Solar Orbiter

    NASA Astrophysics Data System (ADS)

    Löptien, Björn; Birch, Aaron C.; Gizon, Laurent; Schou, Jesper; Appourchaux, Thierry; Blanco Rodríguez, Julián; Cally, Paul S.; Dominguez-Tagle, Carlos; Gandorfer, Achim; Hill, Frank; Hirzberger, Johann; Scherrer, Philip H.; Solanki, Sami K.

    2015-12-01

    The Solar Orbiter mission, to be launched in July 2017, will carry a suite of remote sensing and in-situ instruments, including the Polarimetric and Helioseismic Imager (PHI). PHI will deliver high-cadence images of the Sun in intensity and Doppler velocity suitable for carrying out novel helioseismic studies. The orbit of the Solar Orbiter spacecraft will reach a solar latitude of up to 21∘ (up to 34∘ by the end of the extended mission) and thus will enable the first local helioseismology studies of the polar regions. Here we consider an array of science objectives to be addressed by helioseismology within the baseline telemetry allocation (51 Gbit per orbit, current baseline) and within the science observing windows (baseline 3×10 days per orbit). A particularly important objective is the measurement of large-scale flows at high latitudes (rotation and meridional flow), which are largely unknown but play an important role in flux transport dynamos. For both helioseismology and feature tracking methods convection is a source of noise in the measurement of longitudinally averaged large-scale flows, which decreases as T -1/2 where T is the total duration of the observations. Therefore, the detection of small amplitude signals (e.g., meridional circulation, flows in the deep solar interior) requires long observation times. As an example, one hundred days of observations at lower spatial resolution would provide a noise level of about three m/s on the meridional flow at 80∘ latitude. Longer time-series are also needed to study temporal variations with the solar cycle. The full range of Earth-Sun-spacecraft angles provided by the orbit will enable helioseismology from two vantage points by combining PHI with another instrument: stereoscopic helioseismology will allow the study of the deep solar interior and a better understanding of the physics of solar oscillations in both quiet Sun and sunspots. We have used a model of the PHI instrument to study its

  20. Flight Test Results on the Stability and Control of the F-15B Quiet Spike Aircraft

    NASA Technical Reports Server (NTRS)

    Moua, Cheng; McWherter, Shaun H.; Cox, Timothy H.; Gera, Joseph

    2007-01-01

    The Quiet Spike (QS) flight research program was an aerodynamic and structural proof-of-concept of a telescoping sonic-boom suppressing nose boom on an F-15 B aircraft. The program goal was to collect flight data for model validation up to 1.8 Mach. The primary test philosophy was maintaining safety of flight. In the area of stability and controls the primary concerns were to assess the potential destabilizing effect of the spike on the stability, controllability, and handling qualities of the aircraft and to ensure adequate stability margins across the entire QS flight envelop. This paper reports on the stability and control methods used for flight envelope clearance and flight test results of the F-15B Quiet Spike. Also discussed are the flight test approach, the criteria to proceed to the next flight condition, brief pilot commentary on typical piloting tasks, approach and landing, and refueling task, and air data sensitivity to the flight control system.

  1. Quiet-time observation of a coherent compressional Pc-4 micropulsation at synchronous altitude

    NASA Technical Reports Server (NTRS)

    Paulikas, G. A.; Schulz, M.; Barfield, J. N.; Lanzerotti, L. J.; Maclennan, C. G.

    1971-01-01

    During a magnetically quiet interval the magnetic-field intensity and energetic electron fluxes at ATS 1 exhibited coherent modulations having a frequency of 33.8 cph and a duration of approximately 40 oscillations. The electron fluxes and the magnetic field oscillated in phase. The field perturbation reached 8 jamma (peak to peak) in the direction of the unperturbed geomagnetic field. The transverse component of the field perturbation was practically zero. The characteristics of the observed oscillations appear compatible with those of a compressional excitation of the outer magnetosphere. The substantially radial normal mode is perhaps driven by a bounce-resonant interaction with the 15-keV protons that populate the quiet-day ring current.

  2. X-RAY PULSATIONS FROM THE RADIO-QUIET GAMMA-RAY PULSAR IN CTA 1

    SciTech Connect

    Caraveo, P. A.; De Luca, A.; Marelli, M.; Bignami, G. F.; Ray, P. S.; Saz Parkinson, P. M.; Kanbach, G.

    2010-12-10

    Prompted by the Fermi-LAT discovery of a radio-quiet gamma-ray pulsar inside the CTA 1 supernova remnant, we obtained a 130 ks XMM-Newton observation to assess the timing behavior of this pulsar. Exploiting both the unprecedented photon harvest and the contemporary Fermi-LAT timing measurements, a 4.7{sigma} single-peak pulsation is detected, making PSR J0007+7303 the second example, after Geminga, of a radio-quiet gamma-ray pulsar also seen to pulsate in X-rays. Phase-resolved spectroscopy shows that the off-pulse portion of the light curve is dominated by a power-law, non-thermal spectrum, while the X-ray peak emission appears to be mainly of thermal origin, probably from a polar cap heated by magnetospheric return currents, pointing to a hot spot varying throughout the pulsar rotation.

  3. The influence of ankle muscle activation on postural sway during quiet stance.

    PubMed

    Warnica, Meagan J; Weaver, Tyler B; Prentice, Stephen D; Laing, Andrew C

    2014-04-01

    Although balance during quiet standing is postulated to be influenced by multiple factors, including ankle stiffness, it is unclear how different mechanisms underlying increases in stiffness affect balance control. Accordingly, this study examined the influence of muscle activation and passive ankle stiffness increases on the magnitude and frequency of postural sway. Sixteen young adults participated in six quiet stance conditions including: relaxed standing, four muscle active conditions (10%, 20%, 30% and 40% maximum voluntary contraction (MVC)), and one passive condition wearing an ankle foot orthotic (AFO). Kinetics were collected from a force plate, while whole-body kinematics were collected with a 12-sensor motion capture system. Bilateral electromyographic signals were recorded from the tibialis anterior and medial gastrocnemius muscles. Quiet stance sway amplitude (range and root mean square) and frequency (mean frequency and velocity) in the sagittal plane were calculated from time-varying centre of gravity (COG) and centre of pressure (COP) data. Compared to the relaxed standing condition, metrics of sway amplitude were significantly increased (between 37.5 and 63.2%) at muscle activation levels of 30% and 40% MVC. Similarly, frequency measures increased between 30.5 and 154.2% in the 20-40% MVC conditions. In contrast, passive ankle stiffness, induced through the AFO, significantly decreased sway amplitude (by 23-26%), decreased COG velocity by 13.8%, and increased mean COP frequency by 24.9%. These results demonstrate that active co-contraction of ankle musculature (common in Parkinson's Disease patients) may have differential effects on quiet stance balance control compared to the use of an ankle foot orthotic (common for those recovering from stroke). PMID:24613374

  4. Massive Infrared-Quiet Dense Cores: Unveiling the Initial Conditions of High-Mass Star Formation

    NASA Astrophysics Data System (ADS)

    Motte, F.; Bontemps, S.; Schneider, N.; Schilke, P.; Menten, K. M.

    2008-05-01

    As Th. Henning said at the conference, cold precursors of high-mass stars are now ``hot topics''. We here propose some observational criteria to identify massive infrared-quiet dense cores which can host the high-mass analogs of Class~0 protostars and pre-stellar condensations. We also show how far-infrared to millimeter imaging surveys of entire complexes forming OB stars are starting to unveil the initial conditions of high-mass star formation.

  5. Quiet Clean Short-haul Experimental Engine (QCSEE) Under-The-Wing (UTW) composite nacelle

    NASA Technical Reports Server (NTRS)

    Johnston, E. A.

    1978-01-01

    The detail design of the under the wing experimental composite nacelle components is summarized. Analysis of an inlet, fan bypass duct doors, core cowl doors, and variable fan nozzle are given. The required technology to meet propulsion system performance, weight, and operational characteristics is discussed. The materials, design, and fabrication technology for quiet propulsion systems which will yield installed thrust to weight ratios greater than 3.5 to 1 are described.

  6. Neural-mechanical feedback control scheme generates physiological ankle torque fluctuation during quiet stance.

    PubMed

    Vette, Albert H; Masani, Kei; Nakazawa, Kimitaka; Popovic, Milos R

    2010-02-01

    We have recently demonstrated in simulations and experiments that a proportional and derivative (PD) feedback controller can regulate the active ankle torque during quiet stance and stabilize the body despite a long sensory-motor time delay. The purpose of the present study was to: 1) model the active and passive ankle torque mechanisms and identify their contributions to the total ankle torque during standing and 2) investigate whether a neural-mechanical control scheme that implements the PD controller as the neural controller can successfully generate the total ankle torque as observed in healthy individuals during quiet stance. Fourteen young subjects were asked to stand still on a force platform to acquire data for model optimization and validation. During two trials of 30 s each, the fluctuation of the body angle, the electromyogram of the right soleus muscle, and the ankle torque were recorded. Using these data, the parameters of: 1) the active and passive torque mechanisms (Model I) and 2) the PD controller within the neural-mechanical control scheme (Model II) were optimized to achieve potential matching between the measured and predicted ankle torque. The performance of the two models was finally validated with a new set of data. Our results indicate that not only the passive, but also the active ankle torque mechanism contributes significantly to the total ankle torque and, hence, to body stabilization during quiet stance. In addition, we conclude that the proposed neural-mechanical control scheme successfully mimics the physiological control strategy during quiet stance and that a PD controller is a legitimate model for the strategy that the central nervous system applies to regulate the active ankle torque in spite of a long sensory-motor time delay. PMID:20071280

  7. Road Traffic Noise and Annoyance: A Quantification of the Effect of Quiet Side Exposure at Dwellings

    PubMed Central

    de Kluizenaar, Yvonne; Janssen, Sabine A.; Vos, Henk; Salomons, Erik M.; Zhou, Han; van den Berg, Frits

    2013-01-01

    Previous studies indicate that residents may benefit from a “quiet side” to their dwellings. The influence of the level of road traffic noise exposure at the least exposed side on road traffic noise annoyance was studied in Amsterdam, The Netherlands. Road traffic noise exposure was assessed at the most and least exposed façade (Lden,most and Lden,least respectively) of dwellings for subjects in a population based survey (N = 1,967). It was investigated if and to what extent relative quietness at the least exposed façade affected the level of road traffic noise annoyance by comparing two groups: (1) The subgroup with a relatively quiet façade; (2) the subgroup without a relatively quiet façade (large versus small difference in exposure between most and least exposed façade; DIF ≥ 10 dB and DIF < 10 dB respectively). In addition, it was investigated if and to what extent Lden,least affected the level of road traffic noise annoyance. Results indicate a significantly lower road traffic noise annoyance score at a given Lden,most, in the subgroup with DIF ≥ 10 dB versus DIF < 10 dB. Furthermore, results suggest an effect of Lden,least independent of Lden,most. The estimated size of the effect expressed in an equivalent change in Lden,most approximated 5 dB for both the difference between the two subgroups (DIF ≥ 10 dB and DIF < 10 dB), and for a 10 dB change in Lden,least. PMID:23736655

  8. A proposed space mission around the Moon to measure the Moon Radio-Quiet Zone

    NASA Astrophysics Data System (ADS)

    Antonietti, N.; Pagana, G.; Pluchino, S.; Maccone, C.

    In a series of papers published since 2000 mainly in Acta Astronautica the senior author Maccone dealt with the advantages of the Farside of the Moon for future utilization Clearly the Moon Farside is free from RFI Radio Frequency Interference produced in larger and larger amounts by the increasing human exploitation of radio technologies That author suggested that crater Daedalus located at the center of the Farside was the best possible location to build up in the future one or more radiotelescopes or phased arrays to achieve the maximum sensitivity in radioastronomical and SETI searches Also a radio-quiet region of space above the Farside of the Moon exists and is called the Quiet Cone The Quiet Cone actual size however is largely unknown since it depends on the orbits of radio-emitting satellites around the Earth that are themselves largely unknown due to the military involvements In addition diffraction of electromagnetic waves grazing the surface of the Moon causes further changes in the geometrical shape of the Quiet Cone This riddle can be solved only by direct measurements of the radio attenuation above the Farside of the Moon performed by satellites orbiting the Moon itself In this paper we propose to let one or more low cost radiometers be put into orbit around the Moon to measure the RFI attenuation at different frequencies and altitudes above the Moon The opportunity of adding more payload s such as an ion detector and or a temperature sensor is evaluated also In this regard we present in this paper the experience gained by

  9. A quiet-flow Ludwieg tube for experimental study of high speed boundary layer transition

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1992-01-01

    A new low Reynolds number quiet-flow Ludwieg tube facility, now under construction, is briefly described, and its advantages outlined. The facility is characterized by good optical access and may be particularly useful for the development of optical instrumentation for the generation and measurement of instability waves. Initial research plans also include work on hot-wire instrumentation, wave generation techniques, roughness and receptivity effects, and suction distribution effects.

  10. Electron collisional excitation and resonant photoexcitation of solar S XI

    NASA Technical Reports Server (NTRS)

    Kastner, S. O.; Bhatia, A. K.

    1986-01-01

    The line emission of carbon-like S XI is predicted using a comprehensive 46-level model including the configurations 2p2, 2s2p3, 2p3s, 2p4, 2p3p, 2p3d. Relative intensities of allowed, intercombination, and forbidden lines are computed for quiet and active solar conditions. The process of photoexcitation by the Fe XIII 191.26 A line is included to study its effect on EUV lines and the infrared forbidden lines at 1.92 and 1.39 microns. It is concluded that an observation of the 1.92-micron line by Olsen, Anderson, and Stewart (1971) is consistent with quiet solar conditions in the absence of photoexcitation.

  11. Solar activity dependence of nightside aurora in winter conditions

    NASA Astrophysics Data System (ADS)

    Zhou, Su; Luan, Xiaoli; Dou, Xiankang

    2016-02-01

    The dependence of the nightside (21:00-03:00 MLT; magnetic local time) auroral energy flux on solar activity was quantitatively studied for winter/dark and geomagnetically quiet conditions. Using data combined from Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager and Defense Meteorological Satellite Program/Special Sensor Ultraviolet Spectrographic Imager observations, we separated the effects of geomagnetic activity from those of solar flux on the nightside auroral precipitation. The results showed that the nightside auroral power was reduced by ~42% in solar maximum (F10.7 = 200 sfu; solar flux unit 1 sfu = 10-22 W m-2 Hz-1) with respect to that under solar minimum (F10.7 = 70 sfu) for the Kp = 1 condition, and this change rate became less (~21%) for the Kp = 3 condition. In addition, the solar cycle dependence of nightside auroral power was similar with that from both the premidnight (21:00-23:00 MLT) and postmidnight (01:00-03:00 MLT) sectors. These results indicated that as the ionospheric ionization increases with the enhanced auroral and geomagnetic activities, the solar activity dependences of nightside auroral power become weaker, at least under geomagnetically quiet conditions.

  12. Center of pressure velocity reflects body acceleration rather than body velocity during quiet standing.

    PubMed

    Masani, Kei; Vette, Albert H; Abe, Masaki O; Nakazawa, Kimitaka

    2014-03-01

    The purpose of this study was to test the hypothesis that the center of pressure (COP) velocity reflects the center of mass (COM) acceleration due to a large derivative gain in the neural control system during quiet standing. Twenty-seven young (27.2±4.5 years) and twenty-three elderly (66.2±5.0 years) subjects participated in this study. Each subject was requested to stand quietly on a force plate for five trials, each 90 s long. The COP and COM displacements, the COP and COM velocities, and the COM acceleration were acquired via a force plate and a laser displacement sensor. The amount of fluctuation of each variable was quantified using the root mean square. Following the experimental study, a simulation study was executed to investigate the experimental findings. The experimental results revealed that the COP velocity was correlated with the COM velocity, but more highly correlated with the COM acceleration. The equation of motion of the inverted pendulum model, however, accounts only for the correlation between the COP and COM velocities. These experimental results can be meaningfully explained by the simulation study, which indicated that the neural motor command presumably contains a significant portion that is proportional to body velocity. In conclusion, the COP velocity fluctuation reflects the COM acceleration fluctuation rather than the COM velocity fluctuation, implying that the neural motor command controlling quiet standing posture contains a significant portion that is proportional to body velocity. PMID:24444652

  13. Thermospheric/ionospheric disturbances under quiet and magneto-perturbed conditions

    NASA Astrophysics Data System (ADS)

    Zakharov, Ivan G.; Mozgovaya, O. L.

    2003-04-01

    The basic mechanisms of ionospheric storms (IS) are investigated sufficiently full. Despite of it a quantitative forecast of ionospheric disturbance is not always satisfactory. One of the possible causes can be related to the insufficient account of a background ionospheric. In particualr using electron concentration Ne in the peak of F2-region and total electron content are shown, that the amplitude of a IS positive phase for similar magnetic storms can differ by ~1,5 times. Hence a cause of distinction can be variations in the thermosphere conditions, not reflected by known activity indices. For further research we used the incoherent scatter radar data of the Institute of ionosphere in height range 200-1000 km in the very quiet periods coming to the geomagnetic disturbance. A steady periodic disturbance in Ne during quiet conditions in all heights is established, which can be identified as tidal moda m=6. The amplitude of wave is ~15%, the phase changes with a height. The storm onset leads to an increase of the amplitudes approximately twice without a change in the phase. An ionospheric disturbance in very quiet conditions can lead to additional complicating an ionosphere reaction to magnetic storm.

  14. The Effects of Vision-Related Aspects on Noise Perception of Wind Turbines in Quiet Areas

    PubMed Central

    Maffei, Luigi; Iachini, Tina; Masullo, Massimiliano; Aletta, Francesco; Sorrentino, Francesco; Senese, Vincenzo Paolo; Ruotolo, Francesco

    2013-01-01

    Preserving the soundscape and geographic extension of quiet areas is a great challenge against the wide-spreading of environmental noise. The E.U. Environmental Noise Directive underlines the need to preserve quiet areas as a new aim for the management of noise in European countries. At the same time, due to their low population density, rural areas characterized by suitable wind are considered appropriate locations for installing wind farms. However, despite the fact that wind farms are represented as environmentally friendly projects, these plants are often viewed as visual and audible intruders, that spoil the landscape and generate noise. Even though the correlations are still unclear, it is obvious that visual impacts of wind farms could increase due to their size and coherence with respect to the rural/quiet environment. In this paper, by using the Immersive Virtual Reality technique, some visual and acoustical aspects of the impact of a wind farm on a sample of subjects were assessed and analyzed. The subjects were immersed in a virtual scenario that represented a situation of a typical rural outdoor scenario that they experienced at different distances from the wind turbines. The influence of the number and the colour of wind turbines on global, visual and auditory judgment were investigated. The main results showed that, regarding the number of wind turbines, the visual component has a weak effect on individual reactions, while the colour influences both visual and auditory individual reactions, although in a different way. PMID:23624578

  15. The effects of vision-related aspects on noise perception of wind turbines in quiet areas.

    PubMed

    Maffei, Luigi; Iachini, Tina; Masullo, Massimiliano; Aletta, Francesco; Sorrentino, Francesco; Senese, Vincenzo Paolo; Ruotolo, Francesco

    2013-05-01

    Preserving the soundscape and geographic extension of quiet areas is a great challenge against the wide-spreading of environmental noise. The E.U. Environmental Noise Directive underlines the need to preserve quiet areas as a new aim for the management of noise in European countries. At the same time, due to their low population density, rural areas characterized by suitable wind are considered appropriate locations for installing wind farms. However, despite the fact that wind farms are represented as environmentally friendly projects, these plants are often viewed as visual and audible intruders, that spoil the landscape and generate noise. Even though the correlations are still unclear, it is obvious that visual impacts of wind farms could increase due to their size and coherence with respect to the rural/quiet environment. In this paper, by using the Immersive Virtual Reality technique, some visual and acoustical aspects of the impact of a wind farm on a sample of subjects were assessed and analyzed. The subjects were immersed in a virtual scenario that represented a situation of a typical rural outdoor scenario that they experienced at different distances from the wind turbines. The influence of the number and the colour of wind turbines on global, visual and auditory judgment were investigated. The main results showed that, regarding the number of wind turbines, the visual component has a weak effect on individual reactions, while the colour influences both visual and auditory individual reactions, although in a different way. PMID:23624578

  16. Quiet as an Environmental Value: A Contrast between Two Legislative Approaches

    PubMed Central

    Thorne, Robert; Shepherd, Daniel

    2013-01-01

    This paper examines the concept of “quiet” as an “environmental value” in terms of amenity and wellbeing from a legislative context. Critical review of two pieces of environmental legislation from Australia and New Zealand forms the basis of the paper. The Australian legislation is Queensland’s Environmental Protection Act, and the New Zealand legislation is that nation’s Resource Management Act. Quiet is part of the psychoacoustic continuum between a tranquil and an intrusively noisy sound environment. As such, quiet possesses intrinsic value in terms of overall sound within the environment (soundscape) and to individuals and communities. In both pieces of legislation, guidance, either directly or indirectly, is given to “maximum” sound levels to describe the acoustic environment. Only in Queensland is wellbeing and amenity described as environmental values, while in the New Zealand approach, amenity is identified as the core value to defend, but guidance is not well established. Wellbeing can be related to degrees of quietness and the absence of intrusive noise, the character of sound within an environment (“soundscape”), as well as the overall level of sound. The quality of life experienced by individuals is related to that person’s physical and mental health, sense of amenity and wellbeing. These characteristics can be described in terms of subjective and objective measures, though legislation does not always acknowledge the subjective. PMID:23823712

  17. FULLY RESOLVED QUIET-SUN MAGNETIC FLUX TUBE OBSERVED WITH THE SUNRISE/IMAX INSTRUMENT

    SciTech Connect

    Lagg, A.; Solanki, S. K.; Riethmueller, T. L.; Schuessler, M.; Hirzberger, J.; Feller, A.; Borrero, J. M.; Barthol, P.; Gandorfer, A.; MartInez Pillet, V.; Bonet, J. A.; Del Toro Iniesta, J. C.; Domingo, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    Until today, the small size of magnetic elements in quiet-Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions, to infer their physical properties. A consistent match to the observed Stokes profiles could only be obtained by introducing a magnetic filling factor that specifies the fraction of the observed pixel filled with magnetic field. Here, we investigate the properties of a small magnetic patch in the quiet Sun observed with the IMaX magnetograph on board the balloon-borne telescope SUNRISE with unprecedented spatial resolution and low instrumental stray light. We apply an inversion technique based on the numerical solution of the radiative transfer equation to retrieve the temperature stratification and the field strength in the magnetic patch. The observations can be well reproduced with a one-component, fully magnetized atmosphere with a field strength exceeding 1 kG and a significantly enhanced temperature in the mid to upper photosphere with respect to its surroundings, consistent with semi-empirical flux tube models for plage regions. We therefore conclude that, within the framework of a simple atmospheric model, the IMaX measurements resolve the observed quiet-Sun flux tube.

  18. Fully Resolved Quiet-Sun Magnetic flux Tube Observed with the SUNRISE/IMAX Instrument

    NASA Astrophysics Data System (ADS)

    Lagg, A.; Solanki, S. K.; Riethmüller, T. L.; Martínez Pillet, V.; Schüssler, M.; Hirzberger, J.; Feller, A.; Borrero, J. M.; Schmidt, W.; del Toro Iniesta, J. C.; Bonet, J. A.; Barthol, P.; Berkefeld, T.; Domingo, V.; Gandorfer, A.; Knölker, M.; Title, A. M.

    2010-11-01

    Until today, the small size of magnetic elements in quiet-Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions, to infer their physical properties. A consistent match to the observed Stokes profiles could only be obtained by introducing a magnetic filling factor that specifies the fraction of the observed pixel filled with magnetic field. Here, we investigate the properties of a small magnetic patch in the quiet Sun observed with the IMaX magnetograph on board the balloon-borne telescope SUNRISE with unprecedented spatial resolution and low instrumental stray light. We apply an inversion technique based on the numerical solution of the radiative transfer equation to retrieve the temperature stratification and the field strength in the magnetic patch. The observations can be well reproduced with a one-component, fully magnetized atmosphere with a field strength exceeding 1 kG and a significantly enhanced temperature in the mid to upper photosphere with respect to its surroundings, consistent with semi-empirical flux tube models for plage regions. We therefore conclude that, within the framework of a simple atmospheric model, the IMaX measurements resolve the observed quiet-Sun flux tube.

  19. Investigations to Determine the Origin of the Solar Wind with SPICE and SolarOrbiter

    NASA Astrophysics Data System (ADS)

    Hassler, Donald M.; DeForest, C.; Wilkinson, E.; Davila, J.; SPICE Team

    2011-05-01

    At large spatial scales, the structure of the solar wind and it's mapping back to the solar corona, is thought to be reasonably well understood. However, the detailed structure of the various source regions at chromospheric and transition region heights is extremely complex, and less well understood. Determining this connection between heliospheric structures and their source regions at the Sun is one of the overarching objective of the Solar Orbiter mission. During perihelion segments of its orbit, when the spacecraft is in quasi-corotation with the Sun, Solar Orbiter will determine the plasma parameters and compositional signatures of the solar wind, which can be compared directly with the spectroscopic signatures of coronal ions with differing charge-to-mass ratios and FIP. One of the key instruments on the Solar Orbiter mission to make these remote sensing measurements is the SPICE (Spectral Imaging of the Coronal Environment) imaging spectrograph. SPICE will provide the images and plasma diagnostics needed to characterize the plasma state in different source regions, from active regions to quiet Sun to coronal holes. By comparing composition, plasma parameters, and low/high FIP ratios of structures remotely, with those measured directly at the Solar Orbiter spacecraft, Solar Orbiter will provide the first direct link between solar wind structures and their source regions at the Sun. This talk will provide a background of previous compositional correlation measurements and an outline of the method to be used for comparing the spectroscopic and in-situ plasma parameters to be measured with Solar Orbiter.

  20. Cosmic ray density gradient and its dependence on the north-south asymmetry in solar activity

    NASA Technical Reports Server (NTRS)

    BADRUDDIN; Yadav, R. S.; Yadav, N. R.

    1985-01-01

    An analysis of the diurnal anisotropy on geomagnetically quiet days was performed using neutron monitor data at Deep River, Leeds, Rome and Tokyo, well distributed in latitude and longitude for the period 1964-79. The days were separated according to the polarity of IMF on that day. A significant difference in the amplitude and phase was found on towards and away polarity days, particularly during the years of high solar activity and large north-south asymmetry. These results (particularly time of maximum) on geomagnetically quiet days show some better relationship to the expected results as compared to the results obtained using all the days in a year.

  1. An atlas of solar events: 1996 2005

    NASA Astrophysics Data System (ADS)

    Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M.

    2006-01-01

    Coronal mass ejections (CMEs) are observed in the plane of the sky in coronographic images. As the solar surface is masked by an occulting disk it is not clear whether halo CMEs are directed towards or away from the Earth. Observations of the solar corona on the solar disk by the extreme ultraviolet imaging telescope (EIT) on board the Solar Heliospheric Observatory SoHO can help to resolve this. Quasi-continuous observations of the solar corona were obtained from April 1997 up to the current date at a 12 min cadence in the coronal line of FeXII, as part of a “CME watch program”. At a slower 6 h cadence an additional synoptic program investigates the chromosphere and the corona at four different wavelengths. Large coronal solar events appear when viewing animations of the CME watch program. Fainter events do appear when viewing running difference animations of the CME watch program. When looking for additional spectral information from raw running differences of the synoptic program it is difficult to disentangle intrinsic solar events from the parasitic effect of the solar rotation. We constructed at www.ias.u-psud.fr/medoc/EIT/movies/ an atlas of more than 40,000 difference images from the synoptic programme, corrected for an average solar rotation, as well as more than 200,000 instantaneous and difference images from the CME watch program. We present case studies of specific events in order to investigate the source of darkenings or dimmings in difference images, due to the removal of emitting material, the presence of obscuring material or large changes in temperature. As the beneficial effect of correcting for the solar rotation vanishes at the solar limb, we do not investigate the case of prominence Doppler dimming. As a by-product of the atlas of solar events we obtain a number of quiet time sequences well suited to precisely measure the differential solar rotation by the apparent displacement of tracers.

  2. Solar large-scale positive polarity magnetic fields and geomagnetic disturbances

    NASA Technical Reports Server (NTRS)

    Bumba, V.

    1972-01-01

    Unlike the negative polarity solar magnetic field large-scale regular features that correlate with enhanced solar activity regions, the positive polarity regular formations formed in the weak and old background magnetic fields seem to correlate well with geomagnetically enhanced periods of time (shifted for 4 days), which means that they seem to be the source of the quiet solar wind. This behavior of the large intervals of heliographic longitude with prevailing positive polarity fields may be followed to the end of the 18th cycle, during the declining part of the 19th cycle, and during the first half of the present 20th cycle of solar activity.

  3. Radius of the Sun from observations of the total solar eclipse of 31 July 1981.

    NASA Astrophysics Data System (ADS)

    Akimov, L. A.; Belkina, I. L.; Dyatel, N. P.; Marchenko, G. P.

    The moments of local contacts of 24 points on the east and west solar limbs are determined from the cinematographic solar continuum observations during the 31 July 1981 eclipse. The value of the solar radius averaged over limb regions with different activity was found by the least-squares method - rs = 959.97±0.04″ The solar radius estimates made separately for active and quiet limb regions reveal that the effect of active regions on the measured radius value is significant and may be as much as 0.14″

  4. Recycling of the Solar Corona's Magnetic Field

    NASA Astrophysics Data System (ADS)

    Close, R. M.; Parnell, C. E.; Longcope, D. W.; Priest, E. R.

    2004-09-01

    Magnetic fields play a dominant role in the atmospheres of the Sun and other Sun-like stars. Outside sunspot regions, the photosphere of the so-called quiet Sun contains myriads of small-scale magnetic concentrations, with strengths ranging from the detection limit of ~1016 Mx up to ~3×1020 Mx. The tireless motion of these magnetic flux concentrations, along with the continual appearance and disappearance of opposite-polarity pairs of fluxes, releases a substantial amount of energy that may be associated with a whole host of physical processes in the solar corona, not least the enigma of coronal heating. We find here that the timescale for magnetic flux to be remapped in the quiet-Sun corona is, surprisingly, only 1.4 hr (around 1/10 of the photospheric flux recycling time), implying that the quiet-Sun corona is far more dynamic than previously thought. Besides leading to a fuller understanding of the origins of magnetically driven phenomena in our Sun's corona, such a process may also be crucial for the understanding of stellar atmospheres in general.

  5. Solar radio astronomy at low frequencies

    NASA Technical Reports Server (NTRS)

    Dulk, George A.

    1990-01-01

    The characteristics of solar radio emissions at decametric to kilometric wavelengths are reviewed. Special attention is given to the radiation of the quiet sun at several metric and decametric wavelengths and to nonthermal radiation from the active sun, including radio bursts of type III (electron beams), type-III bursts from behind the sun, storms of type III bursts, the flare-associated radio bursts, type II bursts (shock waves), and shock-associated bursts. It is pointed out that almost no observations have been made so far of solar radiation between about 20 MHz and about 2 MHz. Below about 2 MHz, dynamic spectra of flux densities of solar burst have been recorded in space and observations were made of the directions of centroids and characteristic sizes of the emitting sources.

  6. The solar hydrogen Lyman α to Lyman β line ratio

    NASA Astrophysics Data System (ADS)

    Lemaire, P.; Vial, J.-C.; Curdt, W.; Schühle, U.; Woods, T. N.

    2012-06-01

    Aims: We investigate the variation in the solar hydrogen Lyman α (Lyα) to Lyman β (Lyβ) line ratio as a function of the solar activity by taking into account new results obtained by SoHO/SUMER and TIMED/SEE. Methods: We reanalyze data of quiet and active regions previously collected with the LPSP multichannel instrument on OSO8. We then re-examine data obtained on the solar disk with SUMER and compare them with previous data. In a second step, we use the full Sun H i Lyβ profiles to determine the Lyβ contribution to the SEE profiles obtained with a 0.4 nm full width at half-maximum. The variation in the Lyα to Lyβ line ratio is then measured for part of the solar cycle 23 (2002-2008). Results: We determine the radiance line ratio of the solar H i Lyα to Lyβ line for a quiet Sun area and the relation between the ratio of the Lyα to Lyβ irradiance and the Lyα solar irradiance.

  7. Editorial: solar radiophysics — recent results on observations and theories

    NASA Astrophysics Data System (ADS)

    Nakariakov, Valery M.; Kashapova, Larisa K.; Yan, Yi-Hua

    2014-07-01

    Solar radiophysics is a rapidly developing branch of solar physics and plasma astrophysics. Solar radiophysics has the goal of analyzing observations of radio emissions from the Sun and understanding basic physical processes operating in quiet and active regions of the solar corona. In the near future, the commissioning of a new generation of solar radio observational facilities, which include the Chinese Spectral Radio Heliograph (CSRH) and the upgrade of the Siberian Solar Radio Telescope (SSRT), and the beginning of solar observations with the Atacama Large Millimeter/submillimeter Array (ALMA), is expected to bring us new breakthrough results of a transformative nature. The Marie-Curie International Research Staff Exchange (MC IRSES) “RadioSun” international network aims to create a solid foundation for the successful exploitation of upcoming solar radio observational facilities, as well as intensive use of the existing observational tools, advanced theoretical modeling of relevant physical processes and observables, and training a new generation of solar radio physicists. The RadioSun network links research teams from China, Czech Republic, Poland, Russia and the UK. This mini-volume presents research papers based on invited reviews and contributed talks at the 1st RadioSun workshop in China. These papers cover a broad range of research topics and include recent observational and theoretical advances in solar radiophysics, MHD seismology of the solar corona, physics of solar flares, generation of radio emission, numerical modeling of MHD and plasma physics processes, charged-particle acceleration and novel instrumentation.

  8. Coronal Heating, Spicules, and Solar-B

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Porter, Jason; Hathaway, David; Yamauchi, Yohei

    2003-01-01

    Falconer et al. investigated the heating of the quiet corona by measuring the increase of coronal luminosity with the amount of the magnetic flux in the underlying network at solar minimum when there were no active regions on the face of the Sun. The coronal luminosity was measured from Fe IX/X - Fe XII pairs of coronal images from SOHO/EIT, under the assumption that practically all of the coronal luminosity in these very quiet regions came from plasma in the temperature range 0.9 x 10(exp 6) K is less than or equal to T is less than or equal to 1.3 x 10(exp 6) K. The network magnetic flux content was measured from SOHO/MDI magnetograms. It was found that luminosity of the corona in these quiet regions increased roughly in proportion to the square root of the magnetic flux content of the network and roughly in proportion to the length of the perimeter of the network flux clumps. From 1) this result; 2) the observed occurrence of many fine-scale explosive events (e.g., spicules) at the edges of network flux clumps; and 3) a demonstration that it is energetically feasible for the heating of the corona in quiet regions to be driven by explosions of granule-sized sheared-core magnetic bipoles embedded in the edges of the network flux clumps, Falconer et al. infer that in quiet regions that are not influenced by active regions the corona is mainly heated by such magnetic activity in the edges of the network flux clumps. From their observational results together with their feasibility analysis, Falconer et al. predict that 1) At the edges of the network flux clumps there are many transient sheared core bipoles of the size and lifetime of granules and having transverse field strengths greater than approx. 100 G; 2) Approx. 30 of these bipoles are present per supergranule; and 3) Most spicules are produced by explosions of these bipoles. The photospheric vector magnetograms, chromospheric filtergrams, and EUV spectra from Solar-B are expected to have sufficient sensitivity

  9. The structure of the solar wind in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Lee, Christina On-Yee

    2010-12-01

    This dissertation is devoted to expanding our understanding of the solar wind structure in the inner heliosphere and variations therein with solar activity. Using spacecraft observations and numerical models, the origins of the large-scale structures and long-term trends of the solar wind are explored in order to gain insights on how our Sun determines the space environments of the terrestrial planets. I use long term measurements of the solar wind density, velocity, interplanetary magnetic field, and particles, together with models based on solar magnetic field data, to generate time series of these properties that span one solar rotation (˜27 days). From these time series, I assemble and obtain the synoptic overviews of the solar wind properties. The resulting synoptic overviews show that the solar wind around Mercury, Venus, Earth, and Mars is a complex co-rotating structure with recurring features and occasional transients. During quiet solar conditions, the heliospheric current sheet, which separates the positive interplanetary magnetic field from the negative, usually has a remarkably steady two- or four-sector structure that persists for many solar rotations. Within the sector boundaries are the slow and fast speed solar wind streams that originate from the open coronal magnetic field sources that map to the ecliptic. At the sector boundaries, compressed high-density and the related high-dynamic pressure ridges form where streams from different coronal source regions interact. High fluxes of energetic particles also occur at the boundaries, and are seen most prominently during the quiet solar period. The existence of these recurring features depends on how long-lived are their source regions. In the last decade, 3D numerical solar wind models have become more widely available. They provide important scientific tools for obtaining a more global view of the inner heliosphere and of the relationships between conditions at Mercury, Venus, Earth, and Mars. When

  10. The dynamic character of the polar solar wind

    SciTech Connect

    Jackson, B. V.; Yu, H.-S.; Buffington, A.; Hick, P. P. E-mail: hsyu@ucsd.edu E-mail: pphick@ucsd.edu

    2014-09-20

    The Solar and Heliospheric Observatory (SOHO) Large Angle and Spectrometric Coronagraph C2 and Solar Terrestrial Relations Observatory (STEREO) COR2A coronagraph images, when analyzed using correlation tracking techniques, show a surprising result in places ordinarily thought of as 'quiet' solar wind above the poles in coronal hole regions. Instead of the static well-ordered flow and gradual acceleration normally expected, coronagraph images show outflow in polar coronal holes consisting of a mixture of intermittent slow and fast patches of material. We compare measurements of this highly variable solar wind from C2 and COR2A images and show that both coronagraphs measure essentially the same structures. Measurements of the mean velocity as a function of height of these structures are compared with mass flux determinations of the solar wind outflow in the large polar coronal hole regions and give similar results.

  11. Low energy particle composition. [cosmic rays produced in solar system

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1975-01-01

    A review is given of current knowledge of low-energy cosmic ray particles produced in the solar system. It is argued that the notion that the sun alone can accelerate particles in the solar system must be abandoned in light of evidence that Jupiter and earth may be sources of observed low-energy particles. Measurements of the composition and energy spectra of low-energy particles during quiet times are examined, emphasizing the abundance of protons and helium and of anomalous N, O, and Ne. The abundance of heavy particles (B, C, N, O, Ne, Ca and Fe) of unknown origin in the earth magnetosphere is examined. Reported observations of Jovian electrons are discussed and solar particle events with anomalous compositions (He-3 rich events and Fe rich events) are treated in detail. Nuclear abundances of solar particles, emphasizing their temporal and spatial variations are considered together with the nature of nuclear reaction products in solar flares.

  12. Chromospheric alfvenic waves strong enough to power the solar wind.

    PubMed

    De Pontieu, B; McIntosh, S W; Carlsson, M; Hansteen, V H; Tarbell, T D; Schrijver, C J; Title, A M; Shine, R A; Tsuneta, S; Katsukawa, Y; Ichimoto, K; Suematsu, Y; Shimizu, T; Nagata, S

    2007-12-01

    Alfvén waves have been invoked as a possible mechanism for the heating of the Sun's outer atmosphere, or corona, to millions of degrees and for the acceleration of the solar wind to hundreds of kilometers per second. However, Alfvén waves of sufficient strength have not been unambiguously observed in the solar atmosphere. We used images of high temporal and spatial resolution obtained with the Solar Optical Telescope onboard the Japanese Hinode satellite to reveal that the chromosphere, the region sandwiched between the solar surface and the corona, is permeated by Alfvén waves with strong amplitudes on the order of 10 to 25 kilometers per second and periods of 100 to 500 seconds. Estimates of the energy flux carried by these waves and comparisons with advanced radiative magnetohydrodynamic simulations indicate that such Alfvén waves are energetic enough to accelerate the solar wind and possibly to heat the quiet corona. PMID:18063784

  13. Magnetic Flux Transport and Pressure Variations at Magnetotail Plasma Flow Bursts during Geomagnetically Quiet Times

    NASA Astrophysics Data System (ADS)

    Nowada, M.; Fu, S.-Y.; Parks, G. K.; Pu, Z.-Y.; Angelopoulos, V.; Carlson, C. W.; Auster, H.-U.

    2012-04-01

    The fast plasma flows in the geomagnetotail are observed during both geomagnetically active and quiet times. However, it has been unclear about the fundamental difference in the plasma fast flows between at two different geomagnetic conditions, that is, the generation mechanism of, and pictures of the energy transport and balance at the fast plasma flows. Magnetic reconnection in the magnetotail has been believed as one of the most possible mechanisms to generate the fast plasma flows regardless of the geomagnetic conditions. Recently, Nowada et al. [2012], however, demonstrated that the magnetotail magnetic reconnection does not always contribute to the generation of the fast plasma flows at geomagnetically quiet times based on the THEMIS measurements. It is very important to reveal how the energy transport and balance in the magnetotail in association with these plasma fast flows are on obtaining a clue to elucidate an essential difference in the plasma fast flows between during active and quiet geomagnetic conditions. Based on three events of the magnetotail plasma flow bursts, which are transient fast plasma flows with the durations between 1 and 2 minutes, during geomagnetically quiet times, observed by THEMIS, we examined detailed variations of the electric field as a proxy of the flux transport aspect, and associated pressure. The main characteristics of these events are shown as follows; 1) the GSM-X component of the plasma velocity (Vx) was higher than 300 km/s 2) associated parallel (V//) and perpendicular (V⊥) velocities to the local magnetic field line were higher than 200 km/s 3) the flow bursts were observed during which AL and AU indices were lower than 40 nT, and simultaneous Kp index range was between -1 and 1. For almost events, the parallel (E//) and perpendicular (E⊥) components of the electric field to the local magnetic field line were much stronger than the dawn-dusk electric field component (Ey). This result implies that a larger amount

  14. Intranight polarization variability in radio-loud and radio-quiet AGN

    NASA Astrophysics Data System (ADS)

    Villforth, Carolin; Nilsson, Kari; Østensen, Roy; Heidt, Jochen; Niemi, Sami-Matias; Pforr, Janine

    2009-08-01

    Intranight polarization variability in active galactic nuclei (AGN) has not been studied extensively so far. Studying the variability in polarization makes it possible to distinguish between different emission mechanisms. Thus, it can help answering the question if intranight variability in radio-loud and radio-quiet AGN is of the same or of fundamentally different origin. In this paper, we investigate intranight polarization variability in AGN. Our sample consists of 28 AGN at low to moderate redshifts (0.048 <= z <= 1.036), 12 of which are radio-quiet quasars (RQQs) and 16 are radio-loud blazars. The subsample of blazars consists of eight flat-spectrum radio-quasars (FSRQs) and eight BL Lac objects. Each AGN was observed for a time-span of ~4h in the R band to measure polarization and variability. Using statistical methods, we determine duty cycles for polarized emission and polarization intranight variability. We find clear differences between the two samples. A majority of the radio-loud AGN show moderate to high degrees of polarization, more than half of them also show variability in polarization. There seems to be a dividing line for polarization intranight variability at P ~ 5 per cent over which all objects vary in polarization. We did not find clear correlations between the strength of the variability and the redshift or degree of polarization. Only two out of 12 RQQs show polarized emission, both at levels of P < 1 per cent. The lack of polarization intranight variability in radio-quiet AGN points towards accretion instabilities being the cause for intranight flux variability whereas the high duty cycle of polarization variability in radio-loud objects is more likely caused by instabilities in the jet or changes of physical conditions in the jet plasma. We were able to constrain the time-scale of the detected variations to >4 h. Further studies of intranight polarization variability will be necessary to reveal exact physical conditions behind this

  15. Transient effect of core stability exercises on postural sway during quiet standing.

    PubMed

    Kaji, Ayuko; Sasagawa, Shun; Kubo, Takahiro; Kanehisa, Hiroaki

    2010-02-01

    This study aimed to examine the transient effect of core stability exercises on the motion of the center of pressure (COP) during quiet standing. Seventeen healthy young adults (7 women and 10 men) were required to perform elbow-toe and hand-heel exercises for 30 seconds in both cases. Before and 1 minute after the execution of the 2 exercises, the subjects repeated 30 seconds of quiet standing with eyes closed 3 times on a force platform with intervals of 10 seconds between trials. The intervention of the 2 exercises induced significant decreases in the maximal range of mediolateral sway (34.7 +/- 7.0 mm to 30.2 +/- 6.1 mm, p = 0.0001), standard deviation of mediolateral sway (6.4 +/- 1.2 mm to 5.8 +/- 1.0 mm, p = 0.0006), the mean speed of anteroposterior sway (14.1 +/- 2.5 mm per second to 13.2 +/- 2.3 mm per second, p = 0.004), mean speed of mediolateral sway (22.8 +/- 2.8 mm per second to 20.9 +/- 2.3 mm per second, p = 0.004), sway speed (29.3 +/- 3.9 mm per second to 27.0 +/- 3.2 mm per second, p = 0.002), and sweep speed (73.2 +/- 23.4 mm per second to 62.0 +/- 19.7 mm per second, p = 0.005) of the COP trajectory, calculated from the force platform data. This result indicates that the practice of core stability exercises transiently decreases the area of the COP trajectory and its mediolateral and total excursions during quiet standing with the eyes closed. Performing core stability exercises as part of warm-up programs may be useful for temporarily improving postural control during standing in main exercise programs. PMID:20124792

  16. Factors Affecting Test Results and Standardized Method in Quiet Standing Balance Evaluation

    PubMed Central

    Yoon, Jung Joong; Shin, Bo Mi; Na, Eun Hye

    2012-01-01

    Objective To identify factors affecting test results of the quiet standing balance evaluation conducted by posturography and to investigate the standardized method by comparing results according to feet width. Method The study cohort consisted of 100 healthy individuals. We assessed the quiet standing balance of subjects by using 3 different methods: standing on a force plate with feet width the same as shoulder width (test 1); with feet width the same as half the shoulder width (test 2); with feet width determined by the subject's comfort (test 3). Subjects underwent each test with their eyes open and closed for 30 seconds each time. Parameters for measuring standing balance included the mean mediolateral and anteroposterior extent, speed, and the velocity moment of center of pressure (COP) movement. Results All parameters showed better results when the subject's eyes were open rather than closed, and the mean AP extent and speed increased as the age of the subjects increased (p<0.01). However, there was no significant correlation between height and the study parameters, and no differences between men and women. Mean mediolateral extent and speed were significantly longer and faster in test 1 compared with tests 2 and 3 (p<0.01). The results of test 2 were better than the results of test 3, but the difference was not statistically significant. Conclusion COP movements increased with age and when subjects closed their eyes in an evaluation of quiet standing balance conducted by posturography. Gender and height did not affect results of the test. We suggest that an appropriate method for conducting posturography is to have the subject stand on a force plate with their feet width the same as half the shoulder width, because this posture provided relatively accurate balance capacity. PMID:22506243

  17. Evolution and Luminosity Dependendence of the Hosts of Radio-quiet Quasars

    NASA Astrophysics Data System (ADS)

    Ridgway, S. E.; Heckman, T.; Lacy, M.

    2004-12-01

    The discovery that the nearest galaxies may all contain supermassive black holes, and that the black hole mass and galactic spheroid mass are strongly correlated, implies that most bulge-dominated massive galaxies went through an early quasar phase. Therefore, quasar activity is probably a natural part of the evolution of typical early-type galaxies. To investigate these links between the formation and evolution of the AGN population and that of galaxies, we have been studying the relationship between these populations at moderate and high redshift, where the quasar luminosity function is reaching a maximum. At z ˜ 2 -- 3, we found that faint radio-quiet quasars seem to be associated with L* galaxies, as opposed to the many times L* galaxies associated with the radio-loud objects at similar redshifts. Although the radio-quiet hosts have luminosities and compactnesses similar to the Lyman-break galaxies, their rest-frame UV-optical colors indicate that they may be less actively forming stars. This is roughly consistent with hierarchical schemes of galaxy formation, with these high-redshift, low AGN-luminosity objects still in the process of formation. In contrast, at z ˜ 1, most high-luminosity quasars seem to have very massive hosts, more comparable to those of the radio-loud objects. To determine whether this difference is due to evolution or to the difference in AGN luminosity, we have obtained deep ACS imaging of a sample of lower-luminosity radio-quiet quasar hosts at z ˜ 1. This allows us to study the host galaxy mass as a function of AGN luminosity (and therefore black hole mass) and as a function of redshift. This work has been funded by NASA LTSA grant NAG5-10762 and NASA/STScI HST grant GO-09902.

  18. Spectral Structure of Pc1 Geomagnetic Pulsations under Magnetically Quiet and Disturbed Conditions

    NASA Astrophysics Data System (ADS)

    Feygin, F. Z.; Khabazin, Yu. G.; Kleimenova, N. G.; Malysheva, L. M.

    2016-05-01

    The analysis of geomagnetic Pc1 pulsations recorded in 2006-2010 at the Scandinavian network of the induction magnetometers has been performed. It was found that the spectral structure of Pc1 pulsations was different under the quiet and disturbed magnetic conditions. Analysis of these data showed that in magnetically quiet conditions (Kp ~0-1), in more than 90% of cases, Pc1 pulsations were observed in a narrow frequency band of around 0.2-0.4 Hz with the central oscillation frequency in the series (wave packets) of ~ 0.5-0.7 Hz. Under the disturbed conditions (Kp ~ 2-3), the central frequency of Pc1 waves became almost twice greater (~ 1.0-1.2 Hz) and the spectral width increased up to ~ 0.5-0.7 Hz. The relation of the frequency spectrum width of Pc1 pulsations with magnetospheric parameters was theoretically studied. An analytical expression was obtained and the numerical calculations have been performed. The performed theoretical calculations showed that the evolution of the frequency width of the dynamic spectrum of the Pc1 wave packets depends on the magnetosphere plasma parameters. It was found that the Pc1 spectral width increases with decreasing of the proton thermal anisotropy. We suppose that under quiet conditions, the Pc1 generation can take place inside the plasmasphere but near the plasmapause located at higher L there were small VA values. During the disturbed periods, the Pc1 generation can take place outside the plasmasphere at lower L there were high VA values.

  19. Interjoint dynamic interaction during constrained human quiet standing examined by induced acceleration analysis.

    PubMed

    Sasagawa, Shun; Shinya, Masahiro; Nakazawa, Kimitaka

    2014-01-01

    Recent studies have demonstrated that human quiet standing is a multijoint movement, whereby the central nervous system (CNS) is required to deal with dynamic interactions among the joints to achieve optimal motor performance. The purpose of this study was to investigate how the CNS deals with such interjoint interaction during quiet standing by examining the relationship between the kinetics (torque) and kinematics (angular acceleration) within the multi-degree of freedom system. We modeled quiet standing as a double-link inverted pendulum involving both ankle and hip joints and conducted an "induced acceleration analysis." We found that the net ankle and hip torques induced angular accelerations of comparable magnitudes to the ankle (3.8 ± 1.4°/s(2) and 3.3 ± 1.2°/s(2)) and hip (9.1 ± 3.2°/s(2) and 10.5 ± 3.5°/s(2)) joints, respectively. Angular accelerations induced by the net ankle and hip torques were modulated in a temporally antiphase pattern to one another in each of the two joints. These quantitative and temporal relationships allowed the angular accelerations induced by the two net torques to countercompensate one another, thereby substantially (∼70%) reducing the resultant angular accelerations of the individual joints. These results suggest that, by taking advantage of the interjoint interaction, the CNS prevents the net torques from producing large amplitudes of the resultant angular accelerations when combined with the kinematic effects of all other torques in the chain. PMID:24089399

  20. Universal and individual characteristics of postural sway during quiet standing in healthy young adults

    PubMed Central

    Yamamoto, Tomohisa; Smith, Charles E; Suzuki, Yasuyuki; Kiyono, Ken; Tanahashi, Takao; Sakoda, Saburo; Morasso, Pietro; Nomura, Taishin

    2015-01-01

    The time course of the center of pressure (CoP) during human quiet standing, corresponding to body sway, is a stochastic process, influenced by a variety of features of the underlying neuro-musculo-skeletal system, such as postural stability and flexibility. Due to complexity of the process, sway patterns have been characterized in an empirical way by a number of indices, such as sway size and mean sway velocity. Here, we describe a statistical approach with the aim of estimating “universal” indices, namely parameters that are independent of individual body characteristics and thus are not “hidden” by the presence of individual, daily, and circadian variations of sway; in this manner it is possible to characterize the common aspects of sway dynamics across healthy young adults, in the assumption that they might reflect underlying neural control during quiet standing. Such universal indices are identified by analyzing intra and inter-subject variability of various indices, after sorting out individual-specific indices that contribute to individual discriminations. It is shown that the universal indices characterize mainly slow components of sway, such as scaling exponents of power-law behavior at a low-frequency regime. On the other hand, most of the individual-specific indices contributing to the individual discriminations exhibit significant correlation with body parameters, and they can be associated with fast oscillatory components of sway. These results are consistent with a mechanistic hypothesis claiming that the slow and the fast components of sway are associated, respectively, with neural control and biomechanics, supporting our assumption that the universal characteristics of postural sway might represent neural control strategies during quiet standing. PMID:25780094

  1. An overview of the quiet short-haul research aircraft program

    NASA Technical Reports Server (NTRS)

    Shovlin, M. D.; Cochrane, J. A.

    1978-01-01

    An overview of the Quiet Short Haul Research Aircraft (QSRA) Program is presented, with special emphasis on its propulsion and acoustic aspects. A description of the NASA technical participation in the program including wind tunnel testing, engine ground tests, and advanced aircraft simulation is given. The aircraft and its systems are described and, measured performance, where available, is compared to program goals. Preliminary data indicate that additional research and development are needed in some areas of which acoustics is an example. Some of these additional research areas and potential experiments using the QSRA to develop the technology are discussed. The concept of the QSRA as a national flight research facility is explained.

  2. Cost and schedule management on the quiet short-haul research aircraft project

    NASA Technical Reports Server (NTRS)

    Wilcox, D. E.; Patterakis, P.

    1979-01-01

    The Quiet Short-Haul Research Aircraft (QSRA) Project, one of the largest aeronautical programs undertaken by NASA to date, achieved a significant cost underrun. This is attributed to numerous factors, not the least of which were the contractual arrangement and the system of cost and schedule management employed by the contractor. This paper summarizes that system and the methods used for cost/performance measurement by the contractor and by the NASA project management. Recommendations are made for the use of some of these concepts in particular for future programs of a similar nature.

  3. Numerical Simulations of Nanoflares: PDFs of Released Energy, Waiting Times and Quiet- Sun Magnetic Field Elements

    NASA Astrophysics Data System (ADS)

    Egidi, A.; Viticchie`, B.; Berrilli, F.; Del Moro, D.

    2007-12-01

    A numerical model for nanoflares is proposed to describe probability density functions (PDF) and waiting time statistics of the emitted magnetic energy and to guess PDF of quiet-Sun magnetic field strength. In the simulation, footpoints of reconnecting magnetic loops are advected by photospheric flows computed via a n-body algorithm. The model simulates a system whose behavior is characterized by small scale (i.e., granulation) flows that interact to develop large organization scales (i.e., mesogranulation). Such spatio-temporal correlated flows, incessantly supply , remove and convey the passive magnetic footpoints onto the photospheric surface, triggering reconnections and magnetic field reconfigurations.

  4. Design and Test of Fan/Nacelle Models Quiet High-Speed Fan Design

    NASA Technical Reports Server (NTRS)

    Miller, Christopher J. (Technical Monitor); Repp, Russ; Gentile, David; Hanson, David; Chunduru, Srinivas

    2003-01-01

    The primary objective of the Quiet High-Speed Fan (QHSF) program was to develop an advanced high-speed fan design that will achieve a 6 dB reduction in overall fan noise over a baseline configuration while maintaining similar performance. The program applies and validates acoustic, aerodynamic, aeroelastic, and mechanical design tools developed by NASA, US industry, and academia. The successful fan design will be used in an AlliedSignal Engines (AE) advanced regional engine to be marketed in the year 2000 and beyond. This technology is needed to maintain US industry leadership in the regional turbofan engine market.

  5. Study of quiet turbofan STOL aircraft for short-haul transportation. Volume 6: Systems analysis

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A systems analysis of the quiet turbofan aircraft for short-haul transportation was conducted. The purpose of the study was to integrate the representative data generated by aircraft, market, and economic analyses. Activities of the study were to develop the approach and to refine the methodologies for analytic tradeoff, and sensitivity studies of propulsive lift conceptual aircraft and their performance in simulated regional airlines. The operations of appropriate airlines in each of six geographic regions of the United States were simulated. The offshore domestic regions were evaluated to provide a complete domestic evaluation of the STOL concept applicability.

  6. Quiet sigma delta quantization, and global convergence for a class of asymmetric piecewise-affine maps

    NASA Astrophysics Data System (ADS)

    Ward, Rachel

    2010-09-01

    In this paper, we introduce a family of second-order sigma delta quantization schemes for analog-to-digital conversion which are 'quiet': quantization output is guaranteed to fall to zero at the onset of vanishing input. In the process, we prove that the origin is a globally attractive fixed point for the related family of asymmetrically damped piecewise-affine maps. Our proof of convergence is twofold: first, we construct a trapping set using a Lyapunov-type argument; we then take advantage of the asymmetric structure of the maps under consideration to prove convergence to the origin from within this trapping set.

  7. The quiet time polar cap - DE 1 observations and conceptual model

    NASA Technical Reports Server (NTRS)

    Burch, J. L.; Saflekos, N. A.; Gurnett, D. A.; Craven, J. D.; Frank, L. A.

    1992-01-01

    A conceptual merging model of the magnetosphere is developed which explains DE-1 observations on polar cap plasmas and waves made during a quiet period with a northward IMF when multiple adjacent regions of sunward and antisunward convection were observed. The model involves dayside merging both at high latitudes on open field lines (the usual northward IMF merging) and at lower latitudes on closed field lines. The ratio between the merged flux produced by the high-latitude merging to that produced by the lower-latitude merging increases as the IMF becomes more northward.

  8. Observations of intense ULF pulsation activity near the geomagnetic equator during quiet times

    NASA Technical Reports Server (NTRS)

    Engebretson, M. J.; Zanetti, L. J.; Potemra, T. A.; Klumpar, D. M.; Strangeway, R. J.; Acuna, M. H.

    1988-01-01

    This paper analyzes observations, made by particle and field instruments on the AMPTE CCE satellite, of intense ULF pulsations in the earth's magnetosphere near the geomagnetic equator. These pulsations were observed during magnetically quiet periods in regions characterized by intense fluxes of warm strongly trapped light ions, predominantly H(+), and often with streaming low-energy plasma. The strong latitudinal localization of these pulsations is interpreted to be due to equatorial mass loading or to partial reflection of Alfven wave energy by latitudinal gradients in plasma density. Possible sources of wave energy for these events are discussed.

  9. Study of quiet turbofan STOL aircraft for short-haul transportation. Volume 2: Aircraft

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A study of the quiet turbofan STOL aircraft for short haul transportation was conducted. The objectives of the study were as follows: (1) to determine the relationships between STOL characteristics and economic and social viability of short haul air transportation, (2) to identify critical technology problems involving introduction of STOL short haul systems, (3) to define representative aircraft configurations, characteristics, and costs, and (4) to identify high payoff technology areas to improve STOL systems. The analyses of the aircraft designs which were generated to fulfill the objectives are summarized. The baseline aircraft characteristics are documented and significant trade studies are presented.

  10. Quiet High Speed Fan (QHSF) Flutter Calculations Using the TURBO Code

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Srivastava, Rakesh; Keith, Theo G., Jr.; Min, James B.; Mehmed, Oral

    2006-01-01

    A scale model of the NASA/Honeywell Engines Quiet High Speed Fan (QHSF) encountered flutter wind tunnel testing. This report documents aeroelastic calculations done for the QHSF scale model using the blade vibration capability of the TURBO code. Calculations at design speed were used to quantify the effect of numerical parameters on the aerodynamic damping predictions. This numerical study allowed the selection of appropriate values of these parameters, and also allowed an assessment of the variability in the calculated aerodynamic damping. Calculations were also done at 90 percent of design speed. The predicted trends in aerodynamic damping corresponded to those observed during testing.

  11. Non-Gaussian center-of-pressure velocity distribution during quiet stance

    NASA Astrophysics Data System (ADS)

    Santos, E. S. D.; Picoli, S.; Deprá, P. P.; Mendes, R. S.

    2015-02-01

    In the present study, we investigate patterns in the postural sway that characterize the static balance in human beings. To measure the postural sway, sixteen healthy young subjects performed quiet stance tasks providing the center-of-pressure (COP) trajectories. From these trajectories, we obtained the COP velocities. We verified that the velocity distributions exhibit non-normal behavior and can be approximated by generalized Gaussians with fat tails. We also discuss possible implications of modeling COP velocity by using generalized Fokker-Planck equations related to Tsallis statistics and Richardson anomalous diffusion.

  12. Quiet Clean Short-haul Experimental Engine (QCSEE). Double-annular clean combustor technology development report

    NASA Technical Reports Server (NTRS)

    Bahr, D. W.; Burrus, D. L.; Sabla, P. E.

    1979-01-01

    A sector combustor technology development program was conducted to define an advanced double annular dome combustor sized for use in the quiet clean short haul experimental engine (QCSEE). A design which meets the emission goals, and combustor performance goals of the QCSEE engine program was developed. Key design features were identified which resulted in substantial reduction in carbon monoxide and unburned hydrocarbon emission levels at ground idle operating conditions, in addition to very low nitric oxide emission levels at high power operating conditions. Their significant results are reported.

  13. Study of quiet turbofan STOL aircraft for short-haul transportation. Volume 1: Summary

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Conceptual designs of Quiet Turbofan STOL Short-Haul Transport Aircraft for the mid-1980 time period are developed and analyzed to determine their technical, operational, and economic feasibility. A matrix of aircraft using various high-lift systems and design parameters are considered. Variations in aircraft characteristics, airport geometry and location, and operational techniques are analyzed systematically to determine their effects on the market, operating economics, and community acceptance. The total systems approach is considered to be critically important in analyzing the potential of STOL aircraft to reduce noise pollution and alleviate the increasing air corridor and airport congestion.

  14. Design and Test of Fan/Nacelle Models Quiet High-Speed Fan

    NASA Technical Reports Server (NTRS)

    Miller, Christopher J. (Technical Monitor); Weir, Donald

    2003-01-01

    The Quiet High-Speed Fan program is a cooperative effort between Honeywell Engines & Systems (formerly AlliedSignal Engines & Systems) and the NASA Glenn Research Center. Engines & Systems has designed an advanced high-speed fan that will be tested on the Ultra High Bypass Propulsion Simulator in the NASA Glenn 9 x 15 foot wind tunnel, currently scheduled for the second quarter of 2000. An Engines & Systems modern fan design will be used as a baseline. A nacelle model is provided that is characteristic of a typical, modern regional aircraft nacelle and meets all of the program test objectives.

  15. Quiet Clean Short-Haul Experimental Engine (QCSEE): Acoustic treatment development and design

    NASA Technical Reports Server (NTRS)

    Clemons, A.

    1979-01-01

    Acoustic treatment designs for the quiet clean short-haul experimental engines are defined. The procedures used in the development of each noise-source suppressor device are presented and discussed in detail. A complete description of all treatment concepts considered and the test facilities utilized in obtaining background data used in treatment development are also described. Additional supporting investigations that are complementary to the treatment development work are presented. The expected suppression results for each treatment configuration are given in terms of delta SPL versus frequency and in terms of delta PNdB.

  16. Multi-scale statistical analysis of coronal solar activity

    DOE PAGESBeta

    Gamborino, Diana; del-Castillo-Negrete, Diego; Martinell, Julio J.

    2016-07-08

    Multi-filter images from the solar corona are used to obtain temperature maps that are analyzed using techniques based on proper orthogonal decomposition (POD) in order to extract dynamical and structural information at various scales. Exploring active regions before and after a solar flare and comparing them with quiet regions, we show that the multi-scale behavior presents distinct statistical properties for each case that can be used to characterize the level of activity in a region. Information about the nature of heat transport is also to be extracted from the analysis.

  17. Multi-scale statistical analysis of coronal solar activity

    NASA Astrophysics Data System (ADS)

    Gamborino, Diana; del-Castillo-Negrete, Diego; Martinell, Julio J.

    2016-07-01

    Multi-filter images from the solar corona are used to obtain temperature maps that are analyzed using techniques based on proper orthogonal decomposition (POD) in order to extract dynamical and structural information at various scales. Exploring active regions before and after a solar flare and comparing them with quiet regions, we show that the multi-scale behavior presents distinct statistical properties for each case that can be used to characterize the level of activity in a region. Information about the nature of heat transport is also to be extracted from the analysis.

  18. Nobeyama/SOHO/BBSO Comparison of Solar Polar Coronal Holes

    NASA Astrophysics Data System (ADS)

    Gary, D. E.; Enome, S.; Shibasaki, K.; Gurman, J. B.; Shine, R. A.

    1997-05-01

    Although it is not widely known outside the discipline of solar radiophysics, a long-standing puzzle exists: the poles of the Sun appear brighter than the rest of the quiet Sun in a restricted range of wavelengths roughly from 15 GHz to about 48 GHz (cf. Kosugi et al. 1986). At somewhat lower radio frequencies the poles appear darker than the quiet Sun due to a deficit of coronal material, while at mm-wavelengths the polar and non-polar quiet Sun appear quite uniform due to the similarity of the atmospheric structure at lower heights in the chromosphere. The excess brightness at the poles has also been reported in coronal holes on the disk, and so is apparently related to the phenomenon of coronal holes. The brightening likely corresponds to an elevated temperature in the upper chromosphere in coronal holes relative to normal quiet Sun. The phenomenon is especially well suited to study via radio emission due to the unique sensitivity of radio waves to this height range in the chromosphere. The possibility exists that the different chromospheric structure for coronal holes implied by the radio brightening may offer some clue to the origin of the fast solar wind, which is now well established to arise in coronal holes. Radio brightening of coronal holes is a difficult observational problem because an instrument is needed that can image large areas of the Sun at relatively high resolution. The Nobeyama Radioheliograph has the required capability and operates at 17 and 34 GHz, nicely within the frequency range where the brightening occurs. We compare Nobeyama radio synthesis images on several days in 1996 with images from the EIT, CDS, and MDI experiments on the Solar and Heliospheric Observatory (SOHO) spacecraft, and with high resolution images from the Big Bear Solar Observatory, with the aim of determining the spatial and temporal characteristics of the brightening. We compare the extent of the radio brightening with the boundaries of the coronal holes seen from

  19. The thermal and spatial structure of the solar corona over the cycle and its implication for the coronae of inactive stars

    NASA Astrophysics Data System (ADS)

    Testa, P.; Landi, E.; Saar, S.

    2012-12-01

    We use spectral (SOHO/SUMER and Hinode/EIS) and imaging (Hinode/XRT and SDO/AIA) solar coronal data to systematically measure the thermal structure of different types of solar features (coronal hole, quiet Sun, X-ray bright points, active regions...), and how they vary over the solar cycle. We use a combination of these structures to construct a model for the quiet corona of the inactive G8V star tau Ceti, which is a candidate stellar analog of a solar magnetic minimum. Since tau Ceti is significantly metal-poor relative to the Sun, we reconstruct the solar results with corresponding lower metallicities to generate more appropriate coronal structures.

  20. Segmentation of extreme ultraviolet solar images via multichannel fuzzy clustering

    NASA Astrophysics Data System (ADS)

    Barra, Vincent; Delouille, Véronique; Hochedez, Jean-François

    2008-09-01

    The study of the variability of the solar corona and the monitoring of its traditional regions (Coronal Holes, Quiet Sun and Active Regions) are of great importance in astrophysics as well as in view of the Space Weather and Space Climate applications. Here we propose a multichannel unsupervised spatially constrained fuzzy clustering algorithm that automatically segments EUV solar images into Coronal Holes, Quiet Sun and Active Regions. Fuzzy logic allows to manage the various noises present in the images and the imprecision in the definition of the above regions. The process is fast and automatic. It is applied to SoHO EIT images taken from February 1997 till May 2005, i.e. along almost a full solar cycle. Results in terms of areas and intensity estimations are consistent with previous knowledge. The method reveal the rotational and other mid-term periodicities in the extracted time series across solar cycle 23. Further, such an approach paves the way to bridging observations between spatially resolved data from imaging telescopes and time series from radiometers. Time series resulting form the segmentation of EUV coronal images can indeed provide an essential component in the process of reconstructing the solar spectrum.

  1. Quiet eye and the Bereitschaftspotential: visuomotor mechanisms of expert motor performance.

    PubMed

    Mann, Derek T Y; Coombes, Steven A; Mousseau, Melanie B; Janelle, Christopher M

    2011-08-01

    Concurrent exploration of the Bereitschaftspotential (BP) and quiet eye period (QE) was implemented to assess potential mechanisms underlying psychomotor skills that differentiate expert and near-expert performers. Twenty golfers were classified by their USGA handicap rating as either a high handicap (HH; near-expert) or low handicap (LH; expert) to permit skill-based inferences. Participants completed 90 trials during which QE duration, BP activity, and putting performance were recorded. The application of single-subject analyses illustrated that LH golfers were more accurate and less variable in their performance than the HH group. Systematic differences in QE duration and BP were also observed, with experts exhibiting a prolonged quiet eye period and greater cortical activation in the right-central region compared with non-experts. A significant association between cortical activation and QE duration was also noted. The results of this investigation lend support to the motor programming/preparation function of the QE period. Practical and theoretical implications are presented and suggestions for future empirical work provided. PMID:21465225

  2. English vowel identification in quiet and noise: effects of listeners' native language background

    PubMed Central

    Jin, Su-Hyun; Liu, Chang

    2014-01-01

    Purpose: To investigate the effect of listener's native language (L1) and the types of noise on English vowel identification in noise. Method: Identification of 12 English vowels was measured in quiet and in long-term speech-shaped noise and multi-talker babble (MTB) noise for English- (EN), Chinese- (CN) and Korean-native (KN) listeners at various signal-to-noise ratios (SNRs). Results: Compared to non-native listeners, EN listeners performed significantly better in quiet and in noise. Vowel identification in long-term speech-shaped noise and in MTB noise was similar between CN and KN listeners. This is different from our previous study in which KN listeners performed better than CN listeners in English sentence recognition in MTB noise. Discussion: Results from the current study suggest that depending on speech materials, the effect of non-native listeners' L1 on speech perception in noise may be different. That is, in the perception of speech materials with little linguistic cues like isolated vowels, the characteristics of non-native listener's native language may not play a significant role. On the other hand, in the perception of running speech in which listeners need to use more linguistic cues (e.g., acoustic-phonetic, semantic, and prosodic cues), the non-native listener's native language background might result in a different masking effect. PMID:25400538

  3. Long term average distribution of O+ in the quiet-time terrestrial magnetosphere

    NASA Astrophysics Data System (ADS)

    Liu, Wenlong; Wang, Jing; Cao, Jinbin

    2016-06-01

    Cluster measurements from 2001 to 2011 provide a unique opportunity to study the characteristics of O+ with full spatial coverage between 4 to 19 RE, especially in the mid-latitude region. Three-dimensional spatial distributions of averaged omnidirectional O+ differential fluxes in three energy channels (E1:40-136 eV; E2:136 eV-3 keV; E3:3-30 keV) during quiet times (Dst > -20~nT) are presented in this paper. Comparing the distributions of O+ in three energy channels helps us to better understand the transport and energization of O+. Consistent with previous studies, it is suggested that during quiet times O+ is heated in the high-altitude cusp and mantle, and part of this heated population is transported through the lobes to the plasmasheet, where it is further heated/accelerated. The distributions presented provide important background information for relevant simulation and observation studies of O+ behavior during storm and non-storm times.

  4. Annoyance, Sleep and Concentration Problems due to Combined Traffic Noise and the Benefit of Quiet Side

    PubMed Central

    Bodin, Theo; Björk, Jonas; Ardö, Jonas; Albin, Maria

    2015-01-01

    Background: Access to a quiet side in one’s dwelling is thought to compensate for higher noise levels at the most exposed façade. It has also been indicated that noise from combined traffic sources causes more noise annoyance than equal average levels from either road traffic or railway noise separately. Methods: 2612 persons in Malmö, Sweden, answered to a residential environment survey including questions on outdoor environment, noise sensitivity, noise annoyance, sleep quality and concentration problems. Road traffic and railway noise was modeled using Geographic Information System. Results: Access to a quiet side, i.e., at least one window facing yard, water or green space, was associated with reduced risk of annoyance OR (95%CI) 0.47 (0.38–0.59), and concentration problems 0.76 (0.61–0.95). Bedroom window facing the same environment was associated to reduced risk of reporting of poor sleep quality 0.78 (0.64–1.00). Railway noise was associated with reduced risk of annoyance below 55 dB(A) but not at higher levels of exposure. Conclusions: Having a window facing a yard, water or green space was associated to a substantially reduced risk of noise annoyance and concentration problems. If this window was the bedroom window, sleeping problems were less likely. PMID:25642690

  5. Quiet Cruise Efficient Short Take-off and Landing Subsonic Transport System

    NASA Technical Reports Server (NTRS)

    Kawai, Ron

    2008-01-01

    This NASA funded study conceived a revolutionary airplane concept to enable future traffic growth by using regional air space. This requires a very quiet airplane with STOL capability. Starting with a Blended Wing Body that is cruise efficient with inherent low noise characteristics from forward noise shielding and void of aft downward noise reflections, integration of embedded distributed propulsion enables incorporation of the revolutionary concept for jet noise shielding. Embedded distributed propulsion also enables incorporation of a fan bleed internally blown flap for quiet powered lift. The powered lift provides STOL capability for operation at regional airports with rapid take-off and descent to further reduce flyover noise. This study focused on configuring the total engine noise shielding STOL concept with a BWB airplane using the Boeing Phantom Works WingMOD multidisciplinary optimization code to define a planform that is pitch controllable. The configuration was then sized and mission data developed to enable NASA to assess the flyover and sideline noise. The foundational technologies needed are identified including military dual use benefits.

  6. Quiet Sun mini-coronal mass ejections activated by supergranular flows

    NASA Astrophysics Data System (ADS)

    Innes, D. E.; Genetelli, A.; Attie, R.; Potts, H. E.

    2009-02-01

    Context: The atmosphere of the quiet Sun is controlled by photospheric flows sweeping up concentrations of mixed polarity magnetic field. Along supergranule boundaries and junctions, there is a strong correlation between magnetic flux and bright chromospheric and transition region emission. Aims: The aim is to investigate the relationship between photospheric flows and small flare-like brightenings seen in Extreme Ultraviolet images. Methods: We describe observations of small eruptions seen in quiet Sun images taken with the Extreme UltraViolet Imager (EUVI) on STEREO. The photospheric flows during the eruption build-up phase are investigated by tracking granules in high resolution MDI continuum images. Results: Eruptions with characteristics of small coronal mass ejections (CMEs) occur at the junctions of supergranular cells. The eruptions produce brightening at the onset site, dark cloud or small filament ejections, and faint waves moving with plane-of-sky speeds up to 100 km s-1. In the two examples studied, they appear to be activated by converging and rotating supergranular flows, twisting small concentrations of opposite polarity magnetic field. An estimate of the occurrence rate is about 1400 events per day over the whole Sun. One third of these events seem to be associated with waves. Typically, the waves last for about 30 min and travel a distance of 80 Mm, so at any one time they cover 1/50th of the lower corona. Movies are only available in electronic form at http://www.aanda.org

  7. Deep searches for decametre-wavelength pulsed emission from radio-quiet gamma-ray pulsars

    NASA Astrophysics Data System (ADS)

    Maan, Yogesh; Aswathappa, H. A.

    2014-12-01

    We report the results of extensive follow-up observations of the gamma-ray pulsar J1732-3131, which has recently been detected at decametre wavelengths, and the results of deep searches for the counterparts of nine other radio-quiet gamma-ray pulsars at 34 MHz, using the Gauribidanur radio telescope. No periodic signal from J1732-3131 could be detected above a detection threshold of 8σ, even with an effective integration time of more than 40 h. However, the average profile obtained by combining data from several epochs, at a dispersion measure of 15.44 pc cm-3, is found to be consistent with that from the earlier detection of this pulsar at a confidence level of 99.2 per cent. We present this consistency between the two profiles as evidence that J1732-3131 is a faint radio pulsar with an average flux density of 200-400 mJy at 34 MHz. Despite the extremely bright sky background at such low frequencies, the detection sensitivity of our deep searches is generally comparable to that of higher frequency searches for these pulsars, when scaled using reasonable assumptions about the underlying pulsar spectrum. We provide details of our deep searches, and put stringent upper limits on the decametre-wavelength flux densities of several radio-quiet gamma-ray pulsars.

  8. Stability and Control Analysis of the F-15B Quiet SpikeTM Aircraft

    NASA Technical Reports Server (NTRS)

    McWherter, Shaun C.; Moua, Cheng M.; Gera, Joseph; Cox, Timothy H.

    2009-01-01

    The primary purpose of the Quiet Spike(TradeMark) flight research program was to analyze the aerodynamic, structural, and mechanical proof-of-concept of a large multi-stage telescoping nose spike installed on the National Aeronautics and Space Administration Dryden Flight Research Center (Edwards, California) F-15B airplane. This report describes the preflight stability and control analysis performed to assess the effect of the spike on the stability, controllability, and handling qualities of the airplane; and to develop an envelope expansion approach to maintain safety of flight. The overall flight test objective was to collect flight data to validate the spike structural dynamics and loads model up to Mach 1.8. Other objectives included validating the mechanical feasibility of a morphing fuselage at operational conditions and determining the near-field shock wave characterization. The two main issues relevant to the stability and control objectives were the effects of the spike-influenced aerodynamics on the F-15B airplane flight dynamics, and the air data and angle-of-attack sensors. The analysis covered the sensitivity of the stability margins, and the handling qualities due to aerodynamic variation and the maneuvering limitations of the F-15B Quiet Spike configuration. The results of the analysis and the implications for the flight test program are also presented.

  9. Recognition of accented English in quiet and noise by younger and older listeners

    PubMed Central

    Gordon-Salant, Sandra; Yeni-Komshian, Grace H.; Fitzgibbons, Peter J.

    2010-01-01

    This study investigated the effects of age and hearing loss on perception of accented speech presented in quiet and noise. The relative importance of alterations in phonetic segments vs. temporal patterns in a carrier phrase with accented speech also was examined. English sentences recorded by a native English speaker and a native Spanish speaker, together with hybrid sentences that varied the native language of the speaker of the carrier phrase and the final target word of the sentence were presented to younger and older listeners with normal hearing and older listeners with hearing loss in quiet and noise. Effects of age and hearing loss were observed in both listening environments, but varied with speaker accent. All groups exhibited lower recognition performance for the final target word spoken by the accented speaker compared to that spoken by the native speaker, indicating that alterations in segmental cues due to accent play a prominent role in intelligibility. Effects of the carrier phrase were minimal. The findings indicate that recognition of accented speech, especially in noise, is a particularly challenging communication task for older people. PMID:21110610

  10. Build-up Approach to Updating the Mock Quiet Spike(TM)Beam Model

    NASA Technical Reports Server (NTRS)

    Herrera, Claudia Y.; Pak, Chan-gi

    2007-01-01

    A crucial part of aircraft design is ensuring that the required margin for flutter is satisfied. A trustworthy flutter analysis, which begins by possessing an accurate dynamics model, is necessary for this task. Traditionally, a model was updated manually by fine tuning specific stiffness parameters until the analytical results matched test data. This is a time consuming iterative process. The NASA Dryden Flight Research Center has developed a mode matching code to execute this process in a more efficient manner. Recently, this code was implemented in the F-15B/Quiet Spike (Gulfstream Aerospace Corporation, Savannah, Georgia) model update. A build-up approach requiring several ground vibration test configurations and a series of model updates was implemented to determine the connection stiffness between aircraft and test article. The mode matching code successfully updated various models for the F-15B/Quiet Spike project to within 1 percent error in frequency and the modal assurance criteria values ranged from 88.51-99.42 percent.

  11. Build-up Approach to Updating the Mock Quiet Spike(TradeMark) Beam Model

    NASA Technical Reports Server (NTRS)

    Herrera, Claudia Y.; Pak, Chan-gi

    2007-01-01

    A crucial part of aircraft design is ensuring that the required margin for flutter is satisfied. A trustworthy flutter analysis, which begins by possessing an accurate dynamics model, is necessary for this task. Traditionally, a model was updated manually by fine tuning specific stiffness parameters until the analytical results matched test data. This is a time consuming iterative process. NASA Dryden Flight Research Center has developed a mode matching code to execute this process in a more efficient manner. Recently, this code was implemented in the F-15B/Quiet Spike(TradeMark) (Gulfstream Aerospace Corporation, Savannah, Georgia) model update. A build-up approach requiring several ground vibration test configurations and a series of model updates was implemented in order to determine the connection stiffness between aircraft and test article. The mode matching code successfully updated various models for the F-15B/Quiet Spike(TradeMark) project to within 1 percent error in frequency and the modal assurance criteria values ranged from 88.51-99.42 percent.

  12. Intranight optical variability of radio-quiet weak emission line quasars - IV

    NASA Astrophysics Data System (ADS)

    Kumar, Parveen; Chand, Hum; Gopal-Krishna

    2016-09-01

    We report an extension of our programme to search for radio-quiet BL Lac candidates using intranight optical variability (INOV) as a probe. The present INOV observations cover a well-defined representative set of 10 `radio-quiet weak-emission-line quasars' (RQWLQs), selected from a newly published sample of 46 such sources, derived from the Sloan Digital Sky Survey (Data release 7). Intranight CCD monitoring of the 10 RQWLQs was carried out in 18 sessions lasting at least 3.5 h. For each session, differential light curves of the target RQWLQ were derived relative to two steady comparison stars monitored simultaneously. Combining these new data with those already published by us for 15 RQWLQs monitored in 30 sessions, we estimate an INOV duty cycle of ˜3 per cent for the RQWLQs, which appears inconsistent with BL Lacs. However, the observed INOV events (which occurred in just two of the sessions) are strong (with a fractional variability amplitude ψ > 10 per cent), hence blazar-like. We briefly point out the prospects of an appreciable rise in the estimated INOV duty cycle for RQWLQs with a relatively modest increase in sensitivity for monitoring these rather faint objects.

  13. F-15B Quiet Spike(TradeMark) Aeroservoelastic Flight-Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.

    2007-01-01

    System identification is utilized in the aerospace community for development of simulation models for robust control law design. These models are often described as linear, time-invariant processes and assumed to be uniform throughout the flight envelope. Nevertheless, it is well known that the underlying process is inherently nonlinear. Over the past several decades the controls and biomedical communities have made great advances in developing tools for the identification of nonlin ear systems. In this report, we show the application of one such nonlinear system identification technique, structure detection, for the an alysis of Quiet Spike(TradeMark)(Gulfstream Aerospace Corporation, Savannah, Georgia) aeroservoelastic flight-test data. Structure detectio n is concerned with the selection of a subset of candidate terms that best describe the observed output. Structure computation as a tool fo r black-box modeling may be of critical importance for the development of robust, parsimonious models for the flight-test community. The ob jectives of this study are to demonstrate via analysis of Quiet Spike(TradeMark) aeroservoelastic flight-test data for several flight conditions that: linear models are inefficient for modelling aeroservoelast ic data, nonlinear identification provides a parsimonious model description whilst providing a high percent fit for cross-validated data an d the model structure and parameters vary as the flight condition is altered.

  14. Quiet comfort: noise, otherness, and the mobile production of personal space.

    PubMed

    Hagood, Mack

    2011-01-01

    Marketing, news reports, and reviews of Bose QuietComfort noise-canceling headphones position them as essential gear for the mobile rational actor of the neoliberal market—the business traveler. This article concerns noise-canceling headphones’ utility as soundscaping devices, which render a sense of personal space by mediating sound. The airplane and airport are paradoxical spaces in which the pursuit of freedom impedes its own enjoyment. Rather than fight the discomforts of air travel as a systemic problem, travelers use the tactic of soundscaping to suppress the perceived presence of others. Attention to soundscaping enables the scholar to explore relationships between media, space, freedom, otherness, and selfhood in an era characterized by neoliberalism and increased mobility. Air travel is a moment in which people with diverse backgrounds, beliefs, and bodies crowd together in unusually close proximity. Noise is the sound of individualism and difference in conflict. Noise is othered sound, and like any type of othering, the perception of noise is socially constructed and situated in hierarchies of race, class, age, and gender. The normative QuietComfort user in media representations is white, male, rational, monied, and mobile; women, children, and “chatty” passengers are cast as noisemakers. Moreover, in putting on noise-canceling headphones, diverse selves put on the historically Western subjectivity that has been built into their technology, one that suppresses the noise of difference in favor of the smooth circulation of people, information, and commodities. PMID:22165166

  15. Microwave structure of the quiet sun at 8.5 GHz

    NASA Technical Reports Server (NTRS)

    Gary, Dale E.; Zirin, Harold; Wang, Haimin

    1990-01-01

    Multifrequency VLA observations of the quiet sun near 8.5 GHz are presented. Two regions of the sun were observed, one dominated by an enhanced network corresponding to a decayed active region, and the other corresponding to an enhanced network with no active features. The full-day synthesis maps for both show nearly perfect correspondence to H-alpha images, and to longitudinal magnetograms. The coronal loops were observed to appear as regions of radio emission with no underlying longitudinal magnetic fields, being aligned with H-alpha fibrils in the photosphere, and connecting regions of opposite magnetic polarity. The emission can be modeled as optically thin free-free emission from a coronal loop with a peak axial density of approximately 2.4-2.8 x 10 to the 9th/cu cm, for an assumed coronal temperature of 1-2 x 10 to the 6th K. The quiet chromosphere sources are measured, and the significance of these measurements for existing chromospheric models is discussed.

  16. Complexity and dynamics of switched human balance control during quiet standing.

    PubMed

    Nema, Salam; Kowalczyk, Piotr; Loram, Ian

    2015-10-01

    In this paper, we use a combination of numerical simulations, time series analysis, and complexity measures to investigate the dynamics of switched systems with noise, which are often used as models of human balance control during quiet standing. We link the results with complexity measures found in experimental data of human sway motion during quiet standing. The control model ensuring balance, which we use, is based on an act-and-wait control concept, that is, a human controller is switched on when a certain sway angle is reached. Otherwise, there is no active control present. Given a time series data, we determine how does it look a typical pattern of control strategy in our model system. We detect the switched nonlinearity in the system using a frequency analysis method in the absence of noise. We also analyse the effect of time delay on the existence of limit cycles in the system in the absence of noise. We perform the entropy and detrended fluctuation analyses in view of linking the switchings (and the dead zone) with the occurrences of complexity in the model system in the presence of noise. Finally, we perform the entropy and detrended fluctuation analyses on experimental data and link the results with numerical findings in our model example. PMID:26249846

  17. Implementation of a quiet hour: effect on noise levels and infant sleep states.

    PubMed

    Strauch, C; Brandt, S; Edwards-Beckett, J

    1993-03-01

    It is necessary to decrease environmental stimuli in order to provide developmentally supportive care to the very low birthweight (VLBW) infant, thereby enhancing the sleep/wake cycle and possibly physiologic stability. The purpose of this study was to determine if it was possible to decrease the noise level in the Developmental Unit, and promote sleep states in infants on the unit. After determining control noise levels and infant state, the last hour of each shift was designated a Quiet Hour. During this time, noise levels were monitored in the room in five locations. Infant sleep states were also noted. The results indicate that noise levels decreased significantly on two of the three shifts. Fewer infants were crying during the Quiet Hour than the control period (2.4 vs 14.3 percent), and more were in deep or light sleep (84.5 vs 33.9 percent). This study demonstrates that noise levels in Developmental Units can be significantly decreased, and that the decreased noise levels positively impact infant state. By enhancing sleep states, nurses can enhance the long term developmental outcome of the VLBW infant. However, the reduction of noise is highly dependent on the collaborative efforts of all health care providers within the unit. PMID:8446079

  18. Stability and the maintenance of balance following a perturbation from quiet stance

    NASA Astrophysics Data System (ADS)

    Stirling, J. R.; Zakynthinaki, M. S.

    2004-03-01

    We investigate stability and the maintenance of balance with the use of tools from dynamical systems. In particular we investigate the application of such tools to the study of the ground reaction forces resulting from an athlete being perturbed from quiet stance. We develop a nonlinear model consisting of a set of coupled vector fields for the derivative with respect to time of the angles between the resultant ground reaction forces and the vertical in the anteroposterior and mediolateral directions. This model contains a basin of attraction bound by a closed curve which we call the critical curve. It is only inside this curve that perturbations can be corrected, with the orbit spiraling onto an attractor corresponding to quiet stance. We show how the critical curve and also the strength of the attractor found in the basin of attraction can be fit to model the experimental data (time series) for an individual athlete. We also discuss how our model can be used to identify nonsymmetric behavior caused by muscle imbalances and differences in the ranges of motion on either side of the body.

  19. High resolution deep imaging of a bright radio quiet QSO at z ~ 3

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Ping; He, Wei; Yamada, Toru; Tanaka, Ichi; Iye, Masanori; Ji, Tuo

    2015-05-01

    We have obtained deep J and Ks-band images centered on a bright radio quiet QSO UM 402 (zem = 2.856) using the IRCS camera and adaptive optics systems that are part of the Subaru Telescope, as well as retrieved WFC3/F140W archive images of this object. A faint galaxy (mk = 23.32±0.05 in the Vega magnitude system) that lies ~ 2.4″ north of the QSO sightline has been clearly resolved in all three deep high resolution datasets, and appears as an irregular galaxy with two close components in the Ks-band images (separation ~ 0.3″). Given the small impact parameter (b = 19.6 kpc, at zlls = 2.531), as well as the red color of (J - Ks)Vega ~ 1.6, it might be a candidate galaxy giving rise to the Lyman Limit system absorption at zabs = 2.531 seen in the QSO spectrum. After carefully subtracting the point spread function from the QSO images, the host galaxy of this bright radio quiet QSO at z ~ 3 was marginally revealed. We placed a lower limit on the host component of mk ~ 23.3 according to our analyses. Supported by the National Natural Science Foundation of China.

  20. Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.

    1993-01-01

    The main objective of this work is to develop an interim Quiet (low-disturbance) supersonic wind tunnel for the NASA-Ames Fluid Mechanics Laboratory (FML). The main emphasis is to bring on-line a full-scale Mach 1.6 tunnel as rapidly as possible to impact the NASA High Speed Research Program (HSRP). The development of a cryogenic adaptive nozzle and other sophisticated features of the tunnel will now happen later, after the full scale wind tunnel is in operation. The work under this contract for the period of this report can be summarized as follows: provide aerodynamic design requirements for the NASA-Ames Fluid Mechanics Laboratory (FML) Laminar Flow Supersonic Wind Tunnel (LFSWT); research design parameters for a unique Mach 1.6 drive system for the LFSWT using an 1/8th-scale Proof-of-Concept (PoC) supersonic wind tunnel; carry out boundary layer transition studies in PoC to aid the design of critical components of the LFSWT; appraise the State of the Art in quiet supersonic wind tunnel design; and help develop a supersonic research capability within the FML particularly in the areas of high speed transition measurements and schlieren techniques. The body of this annual report summarizes the work of the Principal Investigator.