Science.gov

Sample records for large scale solar

  1. Large scale processes in the solar nebula.

    NASA Astrophysics Data System (ADS)

    Boss, A. P.

    Most proposed chondrule formation mechanisms involve processes occurring inside the solar nebula, so the large scale (roughly 1 to 10 AU) structure of the nebula is of general interest for any chrondrule-forming mechanism. Chondrules and Ca, Al-rich inclusions (CAIs) might also have been formed as a direct result of the large scale structure of the nebula, such as passage of material through high temperature regions. While recent nebula models do predict the existence of relatively hot regions, the maximum temperatures in the inner planet region may not be high enough to account for chondrule or CAI thermal processing, unless the disk mass is considerably greater than the minimum mass necessary to restore the planets to solar composition. Furthermore, it does not seem to be possible to achieve both rapid heating and rapid cooling of grain assemblages in such a large scale furnace. However, if the accretion flow onto the nebula surface is clumpy, as suggested by observations of variability in young stars, then clump-disk impacts might be energetic enough to launch shock waves which could propagate through the nebula to the midplane, thermally processing any grain aggregates they encounter, and leaving behind a trail of chondrules.

  2. Large scale water lens for solar concentration.

    PubMed

    Mondol, A S; Vogel, B; Bastian, G

    2015-06-01

    Properties of large scale water lenses for solar concentration were investigated. These lenses were built from readily available materials, normal tap water and hyper-elastic linear low density polyethylene foil. Exposed to sunlight, the focal lengths and light intensities in the focal spot were measured and calculated. Their optical properties were modeled with a raytracing software based on the lens shape. We have achieved a good match of experimental and theoretical data by considering wavelength dependent concentration factor, absorption and focal length. The change in light concentration as a function of water volume was examined via the resulting load on the foil and the corresponding change of shape. The latter was extracted from images and modeled by a finite element simulation. PMID:26072893

  3. Timing signatures of large scale solar eruptions

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Hock-Mysliwiec, Rachel; Henry, Timothy; Kirk, Michael S.

    2016-05-01

    We examine the timing signatures of large solar eruptions resulting in flares, CMEs and Solar Energetic Particle events. We probe solar active regions from the chromosphere through the corona, using data from space and ground-based observations, including ISOON, SDO, GONG, and GOES. Our studies include a number of flares and CMEs of mostly the M- and X-strengths as categorized by GOES. We find that the chromospheric signatures of these large eruptions occur 5-30 minutes in advance of coronal high temperature signatures. These timing measurements are then used as inputs to models and reconstruct the eruptive nature of these systems, and explore their utility in forecasts.

  4. Large-scale velocity fields. [of solar rotation

    NASA Technical Reports Server (NTRS)

    Howard, Robert F.; Kichatinov, L. L.; Bogart, Richard S.; Ribes, Elizabeth

    1991-01-01

    The present evaluation of recent observational results bearing on the nature and characteristics of solar rotation gives attention to the status of current understanding on such large-scale velocity-field-associated phenomena as solar supergranulation, mesogranulation, and giant-scale convection. Also noted are theoretical suggestions reconciling theory and observations of giant-scale solar convection. The photosphere's global meridional circulation is suggested by solar rotation models requiring pole-to-equator flows of a few m/sec, as well as by the observed migration of magnetic activity over the solar cycle. The solar rotation exhibits a latitude and cycle dependence which can be understood in terms of a time-dependent convective toroidal roll pattern.

  5. Large-scale liquid scintillation detectors for solar neutrinos

    NASA Astrophysics Data System (ADS)

    Benziger, Jay B.; Calaprice, Frank P.

    2016-04-01

    Large-scale liquid scintillation detectors are capable of providing spectral yields of the low energy solar neutrinos. These detectors require > 100 tons of liquid scintillator with high optical and radiopurity. In this paper requirements for low-energy neutrino detection by liquid scintillation are specified and the procedures to achieve low backgrounds in large-scale liquid scintillation detectors for solar neutrinos are reviewed. The designs, operations and achievements of Borexino, KamLAND and SNO+ in measuring the low-energy solar neutrino fluxes are reviewed.

  6. Geospatial Optimization of Siting Large-Scale Solar Projects

    SciTech Connect

    Macknick, J.; Quinby, T.; Caulfield, E.; Gerritsen, M.; Diffendorfer, J.; Haines, S.

    2014-03-01

    Recent policy and economic conditions have encouraged a renewed interest in developing large-scale solar projects in the U.S. Southwest. However, siting large-scale solar projects is complex. In addition to the quality of the solar resource, solar developers must take into consideration many environmental, social, and economic factors when evaluating a potential site. This report describes a proof-of-concept, Web-based Geographical Information Systems (GIS) tool that evaluates multiple user-defined criteria in an optimization algorithm to inform discussions and decisions regarding the locations of utility-scale solar projects. Existing siting recommendations for large-scale solar projects from governmental and non-governmental organizations are not consistent with each other, are often not transparent in methods, and do not take into consideration the differing priorities of stakeholders. The siting assistance GIS tool we have developed improves upon the existing siting guidelines by being user-driven, transparent, interactive, capable of incorporating multiple criteria, and flexible. This work provides the foundation for a dynamic siting assistance tool that can greatly facilitate siting decisions among multiple stakeholders.

  7. Large-Scale periodic solar velocities: An observational study

    NASA Technical Reports Server (NTRS)

    Dittmer, P. H.

    1977-01-01

    Observations of large-scale solar velocities were made using the mean field telescope and Babcock magnetograph of the Stanford Solar Observatory. Observations were made in the magnetically insensitive ion line at 5124 A, with light from the center (limb) of the disk right (left) circularly polarized, so that the magnetograph measures the difference in wavelength between center and limb. Computer calculations are made of the wavelength difference produced by global pulsations for spherical harmonics up to second order and of the signal produced by displacing the solar image relative to polarizing optics or diffraction grating.

  8. Large-scale processes in the solar nebula

    NASA Technical Reports Server (NTRS)

    Boss, A. P.

    1994-01-01

    Theoretical models of the structure of a minimum mass solar nebula should be able to provide the physical context to help evaluate the efficacy of any mechanism proposed for the formation of chondrules or Ca, Al-rich inclusions (CAI's). These models generally attempt to use the equations of radiative hydrodynamics to calculate the large-scale structure of the solar nebula throughout the planet-forming region. In addition, it has been suggested that chondrules and CAI's (=Ch&CAI's) may have been formed as a direct result of large-scale nebula processing such as passage of material through high-temperature regions associated with the global structure of the nebula. In this report we assess the status of global models of solar nebula structure and of various related mechanisms that have been suggested for Ch and CAI formation.

  9. Large-scale magnetic variances near the South Solar Pole

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.; Kota, J.; Smith, E.; Horbury, T.; Giacalone, J.

    1995-01-01

    We summarize recent Ulysses observations of the variances over large temporal scales in the interplanetary magnetic field components and their increase as Ulysses approached the South Solar Pole. A model of these fluctuations is shown to provide a very good fit to the observed amplitude and temporal variation of the fluctuations. In addition, the model predicts that the transport of cosmic rays in the heliosphere will be significantly altered by this level of fluctuations. In addition to altering the inward diffusion and drift access of cosmic rays over the solar poles, we find that the magnetic fluctuations also imply a large latitudinal diffusion, caused primarily by the associated field-line random walk.

  10. How Large Scales Flows May Influence Solar Activity

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.

    2004-01-01

    Large scale flows within the solar convection zone are the primary drivers of the Sun's magnetic activity cycle and play important roles in shaping the Sun's magnetic field. Differential rotation amplifies the magnetic field through its shearing action and converts poloidal field into toroidal field. Poleward meridional flow near the surface carries magnetic flux that reverses the magnetic poles at about the time of solar maximum. The deeper, equatorward meridional flow can carry magnetic flux back toward the lower latitudes where it erupts through the surface to form tilted active regions that convert toroidal fields into oppositely directed poloidal fields. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun's rotation on convection produce velocity correlations that can maintain both the differential rotation and the meridional circulation. These convective motions can also influence solar activity directly by shaping the magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

  11. Large scale reconstruction of the solar coronal magnetic field

    NASA Astrophysics Data System (ADS)

    Amari, T.; Aly, J.-J.; Chopin, P.; Canou, A.; Mikic, Z.

    2014-10-01

    It is now becoming necessary to access the global magnetic structure of the solar low corona at a large scale in order to understand its physics and more particularly the conditions of energization of the magnetic fields and the multiple connections between distant active regions (ARs) which may trigger eruptive events in an almost coordinated way. Various vector magnetographs, either on board spacecraft or ground-based, currently allow to obtain vector synoptic maps, composite magnetograms made of multiple interactive ARs, and full disk magnetograms. We present a method recently developed for reconstructing the global solar coronal magnetic field as a nonlinear force-free magnetic field in spherical geometry, generalizing our previous results in Cartesian geometry. This method is implemented in the new code XTRAPOLS, which thus appears as an extension of our active region scale code XTRAPOL. We apply our method by performing a reconstruction at a specific time for which we dispose of a set of composite data constituted of a vector magnetogram provided by SDO/HMI, embedded in a larger full disk vector magnetogram provided by the same instrument, finally embedded in a synoptic map provided by SOLIS. It turns out to be possible to access the large scale structure of the corona and its energetic contents, and also the AR scale, at which we recover the presence of a twisted flux rope in equilibrium.

  12. Termination shock response to large-scale solar wind fluctuations

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.

    1994-01-01

    The analysis of data recorded by the Voyager 2 spacecraft indicates the presence of large-scale fluctuations in the solar wind ram pressure on the time scale of tens of days. The amplitude of the fluctuations is highly variable but often lies within a factor of 5 to 10 change from an average or mean value of the ram pressure. Since the spacecraft has presumably not encountered the termination shock yet, these fluctuations should eventually interact with the shock and thereby play a role in determining the shock location. Numerical solutions of the time-dependent gas dynamic equations are used to simulate the response of the termination shock to fluctuations in the solar wind ram pressure comparable to those observed. The primary result of this study is that the maximum shock excursion due to the fluctuations is of the order of 1 AU, which is much smaller than that predicted by other studies. Additional simulations show that the limited movement is due to the fact that the time scale for the termination shock response is substantially larger than the time scale of the fluctuations. It is also shown that the heliopause acts as a barrier for the fluctuations and confines them to the heliosphere.

  13. Terminology of Large-Scale Waves in the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Vršnak, Bojan

    2005-03-01

    This is the fourth in a series of essays on terms used in solar-terrestrial physics that are thought to be in need of clarification. Terms are identified and essays are commissioned by a committee chartered by Division II (Sun and Heliosphere) of the International Astronomical Union. Terminology Committee members include Ed Cliver (chair), Jean-Louis Bougeret, Hilary Cane, Takeo Kosugi, Sara Martin, Rainer Schwenn, and Lidia van Driel-Gestelyi. Authors are asked to review the origins of terms and their current usage/misusage. The goals are to inform the community and to open a discussion. The following article by Bojan Vršnak focuses on terms used to describe large-scale waves in the solar atmosphere, an area of research that has been given great impetus by the images of waves from the Extreme ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO). The committee welcomes suggestions for other terms to address in this forum.

  14. How Large Scale Flows in the Solar Convection Zone may Influence Solar Activity

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.

    2004-01-01

    Large scale flows within the solar convection zone are the primary drivers of the Sun s magnetic activity cycle. Differential rotation can amplify the magnetic field and convert poloidal fields into toroidal fields. Poleward meridional flow near the surface can carry magnetic flux that reverses the magnetic poles and can convert toroidal fields into poloidal fields. The deeper, equatorward meridional flow can carry magnetic flux toward the equator where it can reconnect with oppositely directed fields in the other hemisphere. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun s rotation on convection produce velocity correlations that can maintain the differential rotation and meridional circulation. These convective motions can influence solar activity themselves by shaping the large-scale magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

  15. Detectability of Large-Scale Solar Subsurface Flows

    NASA Astrophysics Data System (ADS)

    Woodard, M.

    2014-04-01

    The accuracy of helioseismic measurement is limited by the stochastic nature of solar oscillations. In this article I use a Gaussian statistical model of the global seismic wave field of the Sun to investigate the noise limitations of direct-modeling analysis of convection-zone-scale flows. The theoretical analysis of noise is based on hypothetical data that cover the entire photosphere, including the portions invisible from the Earth. Noise estimates are derived for measurements of the flow-dependent couplings of global-oscillation modes and for combinations of coupling measurements that isolate vector-spherical-harmonic components of the flow velocity. For current helioseismic observations, which sample only a fraction of the photosphere, the inferred detection limits are best regarded as optimistic limits. The flow-velocity fields considered in this work are assumed to be decomposable into vector-spherical-harmonic functions of degree less than five. The problem of measuring the general velocity field is shown to be similar enough to the well-studied problem of measuring differential rotation to permit rough estimates of flow-detection thresholds to be gleaned from past helioseismic analysis. I estimate that, with existing and anticipated helioseismic datasets, large-scale flow-velocity amplitudes of a few tens of should be detectable near the base of the convection zone.

  16. Large-Scale Nanophotonic Solar Selective Absorbers for High-Efficiency Solar Thermal Energy Conversion.

    PubMed

    Li, Pengfei; Liu, Baoan; Ni, Yizhou; Liew, Kaiyang Kevin; Sze, Jeff; Chen, Shuo; Shen, Sheng

    2015-08-19

    An omnidirectional nanophotonic solar selective absorber is fabricated on a large scale using a template-stripping method. The nanopyramid nickel structure achieves an average absorptance of 95% at a wavelength range below 1.3 μm and a low emittance less than 10% at wavelength >2.5 μm. PMID:26134928

  17. Steps Toward a Large-Scale Solar Image Data Analysis to Differentiate Solar Phenomena

    NASA Astrophysics Data System (ADS)

    Banda, J. M.; Angryk, R. A.; Martens, P. C. H.

    2013-11-01

    We detail the investigation of the first application of several dissimilarity measures for large-scale solar image data analysis. Using a solar-domain-specific benchmark dataset that contains multiple types of phenomena, we analyzed combinations of image parameters with different dissimilarity measures to determine the combinations that will allow us to differentiate between the multiple solar phenomena from both intra-class and inter-class perspectives, where by class we refer to the same types of solar phenomena. We also investigate the problem of reducing data dimensionality by applying multi-dimensional scaling to the dissimilarity matrices that we produced using the previously mentioned combinations. As an early investigation into dimensionality reduction, we investigate by applying multidimensional scaling (MDS) how many MDS components are needed to maintain a good representation of our data (in a new artificial data space) and how many can be discarded to enhance our querying performance. Finally, we present a comparative analysis of several classifiers to determine the quality of the dimensionality reduction achieved with this combination of image parameters, similarity measures, and MDS.

  18. The Case for the Large Scale Development of Solar Energy

    ERIC Educational Resources Information Center

    O'Reilly, S. A.

    1977-01-01

    Traces the history of solar energy development. Discusses global effects (temperature, particle and other pollution) of burning fossil fuels. Provides energy balance equations for solar energy distribution and discusses flat plate collectors, solar cells, photochemical and photobiological conversion of solar energy, heat pumps. (CS)

  19. 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.

  20. Large Scale Wind and Solar Integration in Germany

    SciTech Connect

    Ernst, Bernhard; Schreirer, Uwe; Berster, Frank; Pease, John; Scholz, Cristian; Erbring, Hans-Peter; Schlunke, Stephan; Makarov, Yuri V.

    2010-02-28

    This report provides key information concerning the German experience with integrating of 25 gigawatts of wind and 7 gigawatts of solar power capacity and mitigating its impacts on the electric power system. The report has been prepared based on information provided by the Amprion GmbH and 50Hertz Transmission GmbH managers and engineers to the Bonneville Power Administration (BPA) and Pacific Northwest National Laboratory representatives during their visit to Germany in October 2009. The trip and this report have been sponsored by the BPA Technology Innovation office. Learning from the German experience could help the Bonneville Power Administration engineers to compare and evaluate potential new solutions for managing higher penetrations of wind energy resources in their control area. A broader dissemination of this experience will benefit wind and solar resource integration efforts in the United States.

  1. Solar cycle variation of large-scale coronal structures

    NASA Technical Reports Server (NTRS)

    Antonucci, E.; Duvall, T. L.

    1974-01-01

    A green line intensity variation is associated with the interplanetary and photospheric magnetic sector structure. This effect depends on the solar cycle and occurs with the same amplitude in the latitude range 60 deg N - 60 deg S. Extended longitudinal coronal structures are suggested, which indicate the existence of closed magnetic field lines over the neutral line, separating adjacent regions of opposite polarities on the photospheric surface.

  2. Tradeoffs and synergies between biofuel production and large-scale solar infrastructure in deserts

    NASA Astrophysics Data System (ADS)

    Ravi, S.; Lobell, D. B.; Field, C. B.

    2012-12-01

    Solar energy installations in deserts are on the rise, fueled by technological advances and policy changes. Deserts, with a combination of high solar radiation and availability of large areas unusable for crop production are ideal locations for large scale solar installations. For efficient power generation, solar infrastructures require large amounts of water for operation (mostly for cleaning panels and dust suppression), leading to significant moisture additions to desert soil. A pertinent question is how to use the moisture inputs for sustainable agriculture/biofuel production. We investigated the water requirements for large solar infrastructures in North American deserts and explored the possibilities for integrating biofuel production with solar infrastructure. In co-located systems the possible decline in yields due to shading by solar panels may be offsetted by the benefits of periodic water addition to biofuel crops, simpler dust management and more efficient power generation in solar installations, and decreased impacts on natural habitats and scarce resources in deserts. In particular, we evaluated the potential to integrate solar infrastructure with biomass feedstocks that grow in arid and semi-arid lands (Agave Spp), which are found to produce high yields with minimal water inputs. To this end, we conducted detailed life cycle analysis for these coupled agave biofuel - solar energy systems to explore the tradeoffs and synergies, in the context of energy input-output, water use and carbon emissions.

  3. Large-scale use of solar energy with central receivers

    NASA Astrophysics Data System (ADS)

    Kreith, F.; Meyer, R. T.

    1983-12-01

    The working principles of solar central receiver power plants are outlined and applications are discussed. Heliostat arrays direct sunlight into a receiver cavity mounted on a tower, heating the working fluid in the tower to temperatures exceeding 500 C. The formulation for the image plane and the geometric concentration ratio for a heliostat field are provided, noting that commercial electric power plants will require concentration ratios of 200-1000. Automated controls consider imperfections in the mirrors, tracking errors, and seasonal insolation intensity and angular variations. Membranes may be used instead of rigid heliostat mirrors to reduce costs, while trade-offs exist between the efficiencies of cavity and exterior receivers on the tower. Sensible heat storage has proved most effective for cloudy or nighttime operations. Details of the DOE Solar One 10 MW plant, which began operation in 1982, are provided, with mention given to the 33.6 continuous hours of power generation that have been achieved. Projected costs of commercial installations are $700/kWt, and possible applications include recovering and refining oil, processing natural gas, uranium ore, and sugar cane, drying gypsum board, and manufacturing ammonia.

  4. Helioseismic Evidence for Large-Scale Solar Subsurface Turbulence

    NASA Astrophysics Data System (ADS)

    Woodard, Martin F.

    2016-05-01

    A statistical waveform analysis of subsurface flow was performed on two 720-day time series of SOHO/MDI Medium-l spherical-harmonic coefficients. The time series coincide with epochs of high and low solar activity.Time-dependent coupling-strength coefficients b(s,t;n,l) of modes of the same radial order n and degree l, but different azimuthal order m, were inferred from the waveform analysis. These coefficients are sensitive to flows and general aspherical structure. For odd values of s ≪ l, the coefficient b(s,t;n,l) measures an average over depth of the amplitude of one spherical-harmonic (s,t) component of the toroidal flow velocity field. The depth-dependent weighting function defining the average velocity is the fractional kinetic energy density in radius of modes of the (n,l) multiplet. A mean-square (n,l)-dependent flow velocity was inferred from the b-coefficients for s in the range 5 through 35 for each n and l in the respective ranges 1 through 5 and 120 through 149 for the epochs of high and low activity. A further averaging, over l, yielded a root mean square flow velocity as a function of n for each epoch, which average increases from about 20 m/s at n=1 to 35 m/s at n=5. The inferred velocities are consistent with (though perhaps do not demand) a cellular pattern of flow extending over the vertical range of mode sensitivity, estimated to be a few percent of the solar radius below the photosphere.

  5. A new framework to increase the efficiency of large-scale solar power plants.

    NASA Astrophysics Data System (ADS)

    Alimohammadi, Shahrouz; Kleissl, Jan P.

    2015-11-01

    A new framework to estimate the spatio-temporal behavior of solar power is introduced, which predicts the statistical behavior of power output at utility scale Photo-Voltaic (PV) power plants. The framework is based on spatio-temporal Gaussian Processes Regression (Kriging) models, which incorporates satellite data with the UCSD version of the Weather and Research Forecasting model. This framework is designed to improve the efficiency of the large-scale solar power plants. The results are also validated from measurements of the local pyranometer sensors, and some improvements in different scenarios are observed. Solar energy.

  6. Large-Scale Modeling of the Entry of Solar Wind Ions into the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Berchem, J.; Richard, R. L.; Escoubet, C. P.; Pitout, F.

    2012-12-01

    Ion observations made by multiple spacecraft in the mid-altitude cusps have revealed the complexity of the entry of the solar wind plasma at the magnetospheric boundary. In particular, ion energy-latitude dispersions measured by the Cluster spacecraft often indicate the formation of large-scale structures in ion precipitation. We have carried out large-scale simulations of the entry of ions at the dayside magnetopause. Our study is based on using the time-dependent electric and magnetic fields predicted by three-dimensional global MHD simulations to compute the trajectories of large samples of solar wind ions launched upstream of the bow shock for different solar wind conditions. Particle information collected in the simulations is then analyzed to determine the relation between the structures observed in the cusp and ion injection processes at the magnetospheric boundary. We discuss the results of the study in the context of entry and acceleration processes at the dayside magnetopause.

  7. Transparent solar cells in large scale for energy harvesting in buildings

    NASA Astrophysics Data System (ADS)

    Sygkridou, Dimitra; Rapsomanikis, Andreas; Stathatos, Elias

    2014-10-01

    Dye sensitized solar cells (DSSCs) for almost two decades ago were proposed as low cost alternatives to the conventional amorphous silicon solar cells, owing to the simplicity of their fabrication procedures, practically under ambient conditions with mild chemical processes. At the present work, we will show some recent developments to the fabrication of dye-sensitized solar cells in large scale based on TiO2 while issues that limited their performance will also be presented. Outdoor data measurements are included to verify our conclusions.

  8. Delving Deeper into the Solar Dynamo Mechanism: Alpha Effect, Parity Selection and Large Scale Flows.

    NASA Astrophysics Data System (ADS)

    Nandy, D.

    2003-05-01

    Visible manifestations of the 22 year solar magnetic cycle have been the subject of study spanning centuries starting with the telescopic observations of sunspots by Johann Fabricius, Christoph Scheiner and Galileo Galilei in the early 1600s. Coupled with these observations of magnetic features on the solar surface, the advent of the field of helioseismology in recent years has made it possible to map large scale flows in the solar interior - believed to play a crucial role in sustaining the solar cycle. However, a complete understanding of the hydromagnetic dynamo mechanism that powers this solar cycle remains elusive. Here we report studies of the solar dynamo addressing some of the important unresolved questions regarding the nature and location of the alpha effect, solar magnetic parity selection and the role of large scale flows and their variation, with a goal to understand the exact means by which the Sun generates its magnetic cycle. This study was supported by NASA through SR&T grant NAG5-6110.

  9. Large-scale terrestrial solar cell power generation cost: A preliminary assessment

    NASA Technical Reports Server (NTRS)

    Spakowski, A. E.; Shure, L. I.

    1972-01-01

    A cost study was made to assess the potential of the large-scale use of solar cell power for terrestrial applications. The incentive is the attraction of a zero-pollution source of power for wide-scale use. Unlike many other concepts for low-pollution power generation, even thermal pollution is avoided since only the incident solar flux is utilized. To provide a basis for comparison and a perspective for evaluation, the pertinent technology was treated in two categories: current and optimistic. Factors considered were solar cells, array assembly, power conditioning, site preparation, buildings, maintenance, and operation. The capital investment was assumed to be amortized over 30 years. The useful life of the solar cell array was assumed to be 10 years, and the cases of zero and 50-percent performance deg-radation were considered. Land costs, taxes, and profits were not included in this study because it was found too difficult to provide good generalized estimates of these items. On the basis of the factors considered, it is shown that even for optimistic projections of technology, electric power from large-sclae terrestrial use of solar cells is approximately two to three orders of magnitude more costly than current electric power generation from either fossil or nuclear fuel powerplants. For solar cell power generation to be a viable competitor on a cost basis, technological breakthroughs would be required in both solar cell and array fabrication and in site preparation.

  10. Large-scale plasma transport in the magnetotail during different solar wind conditions

    NASA Astrophysics Data System (ADS)

    Myllys, Minna; Kilpua, Emilia; Pulkkinen, Tuija

    2015-04-01

    We present results from a study on how solar wind conditions affect the energy and plasma transport in the geomagnetic tail and how they modify the large-scale magnetotail configuration. We study the large-scale plasma transport in the magnetotail using tail observations from the five THEMIS spacecrafts during 2008-2011. During this period the THEMIS spacecraft spent a considerable time in the geomagnetic tail allowing us to compile statistical maps of plasma flow and energy transport properties. Furthermore, this time period corresponds to the extended and prolonged solar activity minimum between solar cycle 23 and 24 and relatively quiet rising phase of cycle 24. This allowed us to investigate magnetospheric processes and solar wind-magnetospheric coupling during relatively quiet state of the magnetosphere. In order to separate the role of different solar wind parameters and their activity level on the average sunward and tailward plasma flows and the occurrence rate of fast plasma bursts, the magnetospheric data was binned according to solar wind speed, dynamic pressure and IMF measurements. Our results show that the tailward flow bursts are not dependent on the solar wind conditions, but that the sign of the IMF z-component (GSM coordinates) causes the most visible effect to the occurence rate and pattern of sunward flows.

  11. Observing large-scale solar surface flows with GONG: Investigation of a key element in solar activity buildup

    NASA Technical Reports Server (NTRS)

    Beck, John G.; Simon, George W.; Hathaway, David H.

    1996-01-01

    The Global Oscillation Network Group (GONG) solar telescope network has begun regular operations, and will provide continuous Doppler images of large-scale nearly-steady motions at the solar surface, primarily those due to supergranulation. Not only the Sun's well-known magnetic network, but also flux diffusion, dispersal, and concentration at the surface appear to be controlled by supergranulation. Through such magnetoconvective interactions, magnetic stresses develop, leading to solar activity. We show a Doppler movie made from a 45.5 hr time series obtained 1995 May 9-10 using data from three of the six GONG sites (Learmonth, Tenerife, Tucson), to demonstrate the capability of this system.

  12. Large-scale horizontal flows from SOUP observations of solar granulation

    NASA Technical Reports Server (NTRS)

    November, L. J.; Simon, G. W.; Tarbell, T. D.; Title, A. M.; Ferguson, S. H.

    1987-01-01

    Using high resolution time sequence photographs of solar granulation from the SOUP experiment on Spacelab 2, large scale horizontal flows were observed in the solar surface. The measurement method is based upon a local spatial cross correlation analysis. The horizontal motions have amplitudes in the range 300 to 1000 m/s. Radial outflow of granulation from a sunspot penumbra into surrounding photosphere is a striking new discovery. Both the supergranulation pattern and cellular structures having the scale of mesogranulation are seen. The vertical flows that are inferred by continuity of mass from these observed horizontal flows have larger upflow amplitudes in cell centers than downflow amplitudes at cell boundaries.

  13. Large-scale solar magnetic fields and H-alpha patterns

    NASA Technical Reports Server (NTRS)

    Mcintosh, P. S.

    1972-01-01

    Coronal and interplanetary magnetic fields computed from measurements of large-scale photospheric magnetic fields suffer from interruptions in day-to-day observations and the limitation of using only measurements made near the solar central meridian. Procedures were devised for inferring the lines of polarity reversal from H-alpha solar patrol photographs that map the same large-scale features found on Mt. Wilson magnetograms. These features may be monitored without interruption by combining observations from the global network of observatories associated with NOAA's Space Environment Services Center. The patterns of inferred magnetic fields may be followed accurately as far as 60 deg from central meridian. Such patterns will be used to improve predictions of coronal features during the next solar eclipse.

  14. Reconstruction of the solar coronal magnetic field, from active region to large scale

    NASA Astrophysics Data System (ADS)

    Amari, T.; Canou, A.; Delyon, F.; Aly, J. J.; Frey, P.; Alauzet, F.

    2011-12-01

    The low solar corona is dominated by the magnetic field which is created inside the sun by a dynamo process and then emerges into the atmosphere. This magnetic field plays an important role in most structures and phenomena observed at various wavelengths such as prominences, small and large scale eruptive events, and continuous heating of the plasma, and therefore it is important to understand its three-dimensional properties in order to elaborate efficient theoretical models. Unfortunately, the magnetic field is difficult to measure locally in the hot and tenuous corona. But this can be done at the level of the cooler and denser photosphere, and several instruments with high resolution vector magnetographs are currently available (THEMIS, Imaging Vector Magnetograph (IVM), the Advanced Stokes Polarimeter (ASP), SOLIS, HINODE, Solar Dynamics Observatory (SDO), or will be shortly available by future telescopes such as EST and solar missions as SOLAR-ORBITER. This has lead solar physicists to develop an approach which consists in " reconstructing" the coronal magnetic field from boundary data given on the photosphere. We will discuss some of the issues encountered in solving this problem as well our recent progress and results at the scale of active region scales or the larger one such as full sun scale.

  15. Structure and evolution of the large scale solar and heliospheric magnetic fields. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Hoeksema, J. T.

    1984-01-01

    Structure and evolution of large scale photospheric and coronal magnetic fields in the interval 1976-1983 were studied using observations from the Stanford Solar Observatory and a potential field model. The solar wind in the heliosphere is organized into large regions in which the magnetic field has a componenet either toward or away from the sun. The model predicts the location of the current sheet separating these regions. Near solar minimum, in 1976, the current sheet lay within a few degrees of the solar equator having two extensions north and south of the equator. Soon after minimum the latitudinal extent began to increase. The sheet reached to at least 50 deg from 1978 through 1983. The complex structure near maximum occasionally included multiple current sheets. Large scale structures persist for up to two years during the entire interval. To minimize errors in determining the structure of the heliospheric field particular attention was paid to decreasing the distorting effects of rapid field evolution, finding the optimum source surface radius, determining the correction to the sun's polar field, and handling missing data. The predicted structure agrees with direct interplanetary field measurements taken near the ecliptic and with coronameter and interplanetary scintillation measurements which infer the three dimensional interplanetary magnetic structure. During most of the solar cycle the heliospheric field cannot be adequately described as a dipole.

  16. Global Magnetic Topology and Large-Scale Dynamics of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Titov, Viacheslav; Linker, Jon; Mikic, Zoran; Riley, Pete; Lionello, Roberto; Downs, Cooper; Torok, Tibor

    We consider the global topology of the coronal magnetic field in relation to the large-scale dynamics of the solar corona. Our consideration includes recent results on the structural analysis of this field determined in two different approximations, namely, potential field source surface model and solar magnetohydrodynamic model. We identify similarities and differences between structural features of the magnetic field obtained in these two models and discuss their implications for understanding various large-scale phenomena in the solar corona. The underlying magnetic topology manifests itself in a variety of observed morphological features such as streamers, pseudo-streamers or unipolar streamers, EUV dimmings, flare ribbons, coronal holes, and jets. For each of them, the related magnetic configuration has specific structural features, whose presence has to be not only identified but also verified on its independence from the used field model in order to reliably predict the impact of such features on physical processes in the corona. Among them are magnetic null points and minima, bald patches, separatrix surfaces and quasi-separatrix layers, and open and closed separator field lines. These features form a structural skeleton of the coronal magnetic field and are directly involved through the ubiquitous process of magnetic reconnection in many solar dynamic phenomena such as coronal mass ejections, solar wind, acceleration and transport of energetic particles. We will pinpoint and elucidate in our overview some of such involvements that have recently received a considerable attention in our ongoing projects at Predictive Science.

  17. Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Riley, Peter

    1999-01-01

    This investigation is concerned with the large-scale evolution and topology of Coronal Mass Ejections (CMEs) in the solar wind. During this reporting period we have analyzed a series of low density intervals in the ACE (Advanced Composition Explorer) plasma data set that bear many similarities to CMEs. We have begun a series of 3D, MHD (Magnetohydrodynamics) coronal models to probe potential causes of these events. We also edited two manuscripts concerning the properties of CMEs in the solar wind. One was re-submitted to the Journal of Geophysical Research.

  18. Definitive design of the solar total energy large-scale experiment at Shenandoah, Georgia

    NASA Technical Reports Server (NTRS)

    Hunke, R. W.; Leonard, J. A.

    1981-01-01

    Construction of a Solar Total Energy Large Scale Experiment at Shenandoah, Georgia, is described. The Solar Total Energy System (STES) is designed with capacity to supply electricity and thermal energy to a knitwear plant at the Shenandoah site. The system will provide 400 kilowatts electrical and 3.5 megawatts thermal energy. The STES is a cascaded total energy system configuration. It uses parabolic disch collectors and a steam turbine-generator. The electrical system will be grid connected to the Georgia Power Company system.

  19. Effects of Large-Scale Solar Installations on Dust Mobilization and Air Quality

    NASA Astrophysics Data System (ADS)

    Pratt, J. T.; Singh, D.; Diffenbaugh, N. S.

    2012-12-01

    Large-scale solar projects are increasingly being developed worldwide and many of these installations are located in arid, desert regions. To examine the effects of these projects on regional dust mobilization and air quality, we analyze aerosol product data from NASA's Multi-angle Imaging Spectroradiometer (MISR) at annual and seasonal time intervals near fifteen photovoltaic and solar thermal stations ranging from 5-200 MW (12-4,942 acres) in size. The stations are distributed over eight different countries and were chosen based on size, location and installation date; most of the installations are large-scale, took place in desert climates and were installed between 2006 and 2010. We also consider air quality measurements of particulate matter between 2.5 and 10 micrometers (PM10) from the Environmental Protection Agency (EPA) monitoring sites near and downwind from the project installations in the U.S. We use monthly wind data from the NOAA's National Center for Atmospheric Prediction (NCEP) Global Reanalysis to select the stations downwind from the installations, and then perform statistical analysis on the data to identify any significant changes in these quantities. We find that fourteen of the fifteen regions have lower aerosol product after the start of the installations as well as all six PM10 monitoring stations showing lower particulate matter measurements after construction commenced. Results fail to show any statistically significant differences in aerosol optical index or PM10 measurements before and after the large-scale solar installations. However, many of the large installations are very recent, and there is insufficient data to fully understand the long-term effects on air quality. More data and higher resolution analysis is necessary to better understand the relationship between large-scale solar, dust and air quality.

  20. Constraining Large-Scale Solar Magnetic Field Models with Optical Coronal Observations

    NASA Astrophysics Data System (ADS)

    Uritsky, V. M.; Davila, J. M.; Jones, S. I.

    2015-12-01

    Scientific success of the Solar Probe Plus (SPP) and Solar Orbiter (SO) missions will depend to a large extent on the accuracy of the available coronal magnetic field models describing the connectivity of plasma disturbances in the inner heliosphere with their source regions. We argue that ground based and satellite coronagraph images can provide robust geometric constraints for the next generation of improved coronal magnetic field extrapolation models. In contrast to the previously proposed loop segmentation codes designed for detecting compact closed-field structures above solar active regions, we focus on the large-scale geometry of the open-field coronal regions located at significant radial distances from the solar surface. Details on the new feature detection algorithms will be presented. By applying the developed image processing methodology to high-resolution Mauna Loa Solar Observatory images, we perform an optimized 3D B-line tracing for a full Carrington rotation using the magnetic field extrapolation code presented in a companion talk by S.Jones at al. Tracing results are shown to be in a good qualitative agreement with the large-scalie configuration of the optical corona. Subsequent phases of the project and the related data products for SSP and SO missions as wwll as the supporting global heliospheric simulations will be discussed.

  1. Large-Scale Coronal Heating from "Cool" Activity in the Solar Magnetic Network

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    In Fe XII images from SOHO/EIT, the quiet solar corona shows structure on scales ranging from sub-supergranular (i.e., bright points and coronal network) to multi-supergranular (large-scale corona). In Falconer et al 1998 (Ap.J., 501, 386) we suppressed the large-scale background and found that the network-scale features are predominantly rooted in the magnetic network lanes at the boundaries of the supergranules. Taken together, the coronal network emission and bright point emission are only about 5% of the entire quiet solar coronal Fe XII emission. Here we investigate the relationship between the large-scale corona and the network as seen in three different EIT filters (He II, Fe IX-X, and Fe XII). Using the median-brightness contour, we divide the large-scale Fe XII corona into dim and bright halves, and find that the bright-half/dim half brightness ratio is about 1.5. We also find that the bright half relative to the dim half has 10 times greater total bright point Fe XII emission, 3 times greater Fe XII network emission, 2 times greater Fe IX-X network emission, 1.3 times greater He II network emission, and has 1.5 times more magnetic flux. Also, the cooler network (He II) radiates an order of magnitude more energy than the hotter coronal network (Fe IX-X, and Fe XII). From these results we infer that: 1) The heating of the network and the heating of the large-scale corona each increase roughly linearly with the underlying magnetic flux. 2) The production of network coronal bright points and heating of the coronal network each increase nonlinearly with the magnetic flux. 3) The heating of the large-scale corona is driven by widespread cooler network activity rather than by the exceptional network activity that produces the network coronal bright points and the coronal network. 4) The large-scale corona is heated by a nonthermal process since the driver of its heating is cooler than it is. This work was funded by the Solar Physics Branch of NASA's office of

  2. Statistical Dependence of the Large-Scale Birkeland Currents on Solar Wind Parameters

    NASA Astrophysics Data System (ADS)

    Korth, H.; Anderson, B. J.; Waters, C. L.

    2008-12-01

    Since February 1999, distributions of the large-scale field-aligned Birkeland currents have been derived continuously from magnetic perturbations measured globally by the Iridium constellation of satellites. In a statistical study, over 1500 two-hour intervals (5% of the data) were identified for which the currents were stable to within at least 45% overlap between successive hours, corresponding to conditions in the solar wind were sufficiently stable to obtain reliable Birkeland currents. Organized by the interplanetary magnetic field (IMF) clock angle, the statistical current distributions show familiar Regrion-1 and Region-2 currents for southward IMF, NBZ currents for northward IMF, and a continuous distortion of the currents with IMF clock angle consistent with changes in the location of outflow from magnetopause reconnection (Anderson et al. 2008). Here we extend the statistical analysis to examine the dependence of the large-scale Birkeland currents on solar wind electric field in the plane normal to the Earth-Sun line, Eyz, to assess the sensitivity to the strength of the solar wind dynamo, Alfvén Mach number to assess the influence of dayside reconnection mass loading, and dynamic pressure to investigate the dependence on ram pressure. The current intensities are first corrected for variations in EUV-produced ionospheric conductance, normalizing the current densities to zero dipole tilt conditions. Findings include: (1) with increasing solar wind electric field the large-scale Birkeland currents shift duskward and expand equatorward, and the total current intensifies; (2) the total current intensifies with increasing solar wind dynamic pressure by 0.4 MA/nPa; (3) the total current intensifies with increasing Alfvén Mach number by 0.07 MA per unit Alfvén Mach number change. The analysis and implications are discussed.

  3. Public attitudes regarding large-scale solar energy development in the U.S.

    SciTech Connect

    Carlisle, Juliet E.; Kane, Stephanie L.; Solan, David; Bowman, Madelaine; Joe, Jeffrey C.

    2015-08-01

    Using data collected from both a National sample as well as an oversample in U.S. Southwest, we examine public attitudes toward the construction of utility-scale solar facilities in the U.S. as well as development in one’s own county. Our multivariate analyses assess demographic and sociopsychological factors as well as context in terms of proximity of proposed project by considering the effect of predictors for respondents living in the Southwest versus those from a National sample.We find that the predictors, and impact of the predictors, related to support and opposition to solar development vary in terms of psychological and physical distance. Overall, for respondents living in the U.S. Southwest we find that environmentalism, belief that developers receive too many incentives, and trust in project developers to be significantly related to support and opposition to solar development, in general. When Southwest respondents consider large-scale solar development in their county, the influence of these variables changes so that property value, race, and age only yield influence. Differential effects occur for respondents of our National sample.We believe our findings to be relevant for those outside the U.S. due to the considerable growth PV solar has experienced in the last decade, especially in China, Japan, Germany, and the U.S.

  4. Public attitudes regarding large-scale solar energy development in the U.S.

    DOE PAGESBeta

    Carlisle, Juliet E.; Kane, Stephanie L.; Solan, David; Bowman, Madelaine; Joe, Jeffrey C.

    2015-08-01

    Using data collected from both a National sample as well as an oversample in U.S. Southwest, we examine public attitudes toward the construction of utility-scale solar facilities in the U.S. as well as development in one’s own county. Our multivariate analyses assess demographic and sociopsychological factors as well as context in terms of proximity of proposed project by considering the effect of predictors for respondents living in the Southwest versus those from a National sample.We find that the predictors, and impact of the predictors, related to support and opposition to solar development vary in terms of psychological and physical distance.more » Overall, for respondents living in the U.S. Southwest we find that environmentalism, belief that developers receive too many incentives, and trust in project developers to be significantly related to support and opposition to solar development, in general. When Southwest respondents consider large-scale solar development in their county, the influence of these variables changes so that property value, race, and age only yield influence. Differential effects occur for respondents of our National sample.We believe our findings to be relevant for those outside the U.S. due to the considerable growth PV solar has experienced in the last decade, especially in China, Japan, Germany, and the U.S.« less

  5. Generation and Properties of Large-Scale Non-axisymmetric Magnetic Fields by Solar Dynamo

    NASA Astrophysics Data System (ADS)

    Pipin, Valery; Kosovichev, Alexander

    2015-08-01

    Large-scale non-axisymmetric magnetic fields generated by the solar dynamo, and presumably responsible for the phenomenon of "active longitudes", play an important role in the distribution of solar activity and flares. By calculating 3D mean-field dynamo models, we show that nonlinear coupling between axisymmetric and non-axisymmetric modes, e.g. due to the magnetic feedback on the alpha-effect (see, e.g., [1]), can maintain a large-scale non-axisymmetric dynamo process. Non-axisymmetric random fluctuations of dynamo parameters can be another source for the non-axisymmetric magnetic fields on the Sun. Such fluctuations can provide a mechanism of the magnetic energy transfer from the global field to the non-axisymmetric modes. It is shown that the rotational periods of the non-axisymmetric field correspond to the dynamo process operating in the subsurface shear layer which is located in the range of depths 0.85-0.95R. We find that the magnetic helicity conservation quenches generation of the non-axisymmetric dynamo modes as well as it does for the axisymmetric dynamo. It is concluded that the 3D mean-field non-axisymmetric dynamo models can potentially explain the observed distribution of the solar magnetic activity.1. Moss, D.,Non-axisymmetric solar magnetic fields, 1999, MNRAS, 306, 300On 3/18/2015 2:29 PM, Valery Pipin wrote:

  6. First large-scale statistical search for evidence of pulsations in solar flares

    NASA Astrophysics Data System (ADS)

    Inglis, Andrew; Ireland, Jack; Dennis, Brian R.; Hayes, Laura Ann

    2016-05-01

    The nature of quasi-periodic pulsations in solar flares remains poorly constrained, and the general prevalence of such signals in solar flares is unknown, due to the lack of large-scale studies. Therefore, we perform the first large-scale, statistically robust search for evidence of signals consistent with quasi-periodic pulsations in solar flares, focusing on the 1 - 300 s timescale. We analyse 684 M- and X-class flares observed by GOES in soft X-rays between 2011 February 1 and 2015 December 31. Additionally, we analyse 210 events in the same time interval observed by Fermi/GBM in hard X-rays. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature. From this, we determine the fraction of GOES events and Fermi/GBM events showing signatures consistent with classical descriptions of QPP. A further subset of events, particularly in GOES data, show evidence for very broad enhancements in Fourier power. These latter events may be consistent with signatures where the characteristic timescale is substantially evolving over time, or where complex signal behaviour is present. We also show that, for events where a detection occurred in both Fermi/GBM and GOES datasets, similar characteristic timescales were found with both instruments. We discuss the implications of these results for our understanding of solar flares.

  7. Thermocline Thermal Storage Test for Large-Scale Solar Thermal Power Plants

    SciTech Connect

    ST.LAURENT,STEVEN J.

    2000-08-14

    Solar thermal-to-electric power plants have been tested and investigated at Sandia National Laboratories (SNL) since the late 1970s, and thermal storage has always been an area of key study because it affords an economical method of delivering solar-electricity during non-daylight hours. This paper describes the design considerations of a new, single-tank, thermal storage system and details the benefits of employing this technology in large-scale (10MW to 100MW) solar thermal power plants. Since December 1999, solar engineers at Sandia National Laboratories' National Solar Thermal Test Facility (NSTTF) have designed and are constructing a thermal storage test called the thermocline system. This technology, which employs a single thermocline tank, has the potential to replace the traditional and more expensive two-tank storage systems. The thermocline tank approach uses a mixture of silica sand and quartzite rock to displace a significant portion of the volume in the tank. Then it is filled with the heat transfer fluid, a molten nitrate salt. A thermal gradient separates the hot and cold salt. Loading the tank with the combination of sand, rock, and molten salt instead of just molten salt dramatically reduces the system cost. The typical cost of the molten nitrate salt is $800 per ton versus the cost of the sand and rock portion at $70 per ton. Construction of the thermocline system will be completed in August 2000, and testing will run for two to three months. The testing results will be used to determine the economic viability of the single-tank (thermocline) storage technology for large-scale solar thermal power plants. Also discussed in this paper are the safety issues involving molten nitrate salts and other heat transfer fluids, such as synthetic heat transfer oils, and the impact of these issues on the system design.

  8. Large-scale solar wind streams: Average temporal evolution of parameters

    NASA Astrophysics Data System (ADS)

    Yermolaev, Yuri; Lodkina, Irina; Yermolaev, Michael; Nikolaeva, Nadezhda

    2016-07-01

    In the report we describe the average temporal profiles of plasma and field parameters in the disturbed large-scale types of solar wind (SW): corotating interaction regions (CIR), interplanetary coronal mass ejections (ICME) (both magnetic cloud (MC) and Ejecta), and Sheath as well as the interplanetary shock (IS) on the basis of OMNI database and our Catalog of large-scale solar wind phenomena during 1976-2000 (see website ftp://ftp.iki.rssi.ru/pub/omni/ and paper [Yermolaev et al., 2009]). To consider influence of both the surrounding undisturbed solar wind, and the interaction of the disturbed types of the solar wind on the parameters, we separately analyze the following sequences of the phenomena: (1) SW/CIR/SW, (2) SW/IS/CIR/SW, (3) SW/Ejecta/SW, (4) SW/Sheath/Ejecta/SW, (5) SW/IS/Sheath/Ejecta/SW, (6) SW/MC/SW, (7) SW/Sheath/MC/SW, and (8) SW/IS/Sheath/MC/SW. To take into account the different durations of SW types, we use the double superposed epoch analysis (DSEA) method: rescaling the duration of the interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide [Yermolaev et al., 2010; 2015]. Obtained data allow us to suggest that (1) the behavior of parameters in Sheath and in CIR is very similar not only qualitatively but also quantitatively, and (2) the speed angle phi in ICME changes from 2 to -2deg. while in CIR and Sheath it changes from -2 to 2 deg., i.e., the streams in CIR/Sheath and ICME deviate in the opposite side. The work was supported by the Russian Foundation for Basic Research, project 16-02-00125 and by Program of Presidium of the Russian Academy of Sciences. References: Yermolaev, Yu. I., N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev (2009), Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research, , Vol. 47, No. 2, pp. 81-94. Yermolaev, Y. I., N. S. Nikolaeva, I. G. Lodkina, and M. Y. Yermolaev (2010), Specific interplanetary conditions for CIR

  9. Overview of Small and Large-Scale Space Solar Power Concepts

    NASA Technical Reports Server (NTRS)

    Potter, Seth; Henley, Mark; Howell, Joe; Carrington, Connie; Fikes, John

    2006-01-01

    poles to search for water ice and other frozen volatiles. Near such craters are mountain peaks and highlands that are in near permanent sunlight. Power can be beamed from a collector on a sunlit mountain or crater rim to a rover inside a crater. Near-term applications of space solar power technology can therefore pave the way toward large-scale commercial power from space.

  10. A large-scale dataset of solar event reports from automated feature recognition modules

    NASA Astrophysics Data System (ADS)

    Schuh, Michael A.; Angryk, Rafal A.; Martens, Petrus C.

    2016-05-01

    The massive repository of images of the Sun captured by the Solar Dynamics Observatory (SDO) mission has ushered in the era of Big Data for Solar Physics. In this work, we investigate the entire public collection of events reported to the Heliophysics Event Knowledgebase (HEK) from automated solar feature recognition modules operated by the SDO Feature Finding Team (FFT). With the SDO mission recently surpassing five years of operations, and over 280,000 event reports for seven types of solar phenomena, we present the broadest and most comprehensive large-scale dataset of the SDO FFT modules to date. We also present numerous statistics on these modules, providing valuable contextual information for better understanding and validating of the individual event reports and the entire dataset as a whole. After extensive data cleaning through exploratory data analysis, we highlight several opportunities for knowledge discovery from data (KDD). Through these important prerequisite analyses presented here, the results of KDD from Solar Big Data will be overall more reliable and better understood. As the SDO mission remains operational over the coming years, these datasets will continue to grow in size and value. Future versions of this dataset will be analyzed in the general framework established in this work and maintained publicly online for easy access by the community.

  11. PATHWAYS OF LARGE-SCALE MAGNETIC COUPLINGS BETWEEN SOLAR CORONAL EVENTS

    SciTech Connect

    Schrijver, Carolus J.; Title, Alan M.; DeRosa, Marc L.; Yeates, Anthony R.

    2013-08-20

    The high-cadence, comprehensive view of the solar corona by SDO/AIA shows many events that are widely separated in space while occurring close together in time. In some cases, sets of coronal events are evidently causally related, while in many other instances indirect evidence can be found. We present case studies to highlight a variety of coupling processes involved in coronal events. We find that physical linkages between events do occur, but concur with earlier studies that these couplings appear to be crucial to understanding the initiation of major eruptive or explosive phenomena relatively infrequently. We note that the post-eruption reconfiguration timescale of the large-scale corona, estimated from the extreme-ultraviolet afterglow, is on average longer than the mean time between coronal mass ejections (CMEs), so that many CMEs originate from a corona that is still adjusting from a previous event. We argue that the coronal field is intrinsically global: current systems build up over days to months, the relaxation after eruptions continues over many hours, and evolving connections easily span much of a hemisphere. This needs to be reflected in our modeling of the connections from the solar surface into the heliosphere to properly model the solar wind, its perturbations, and the generation and propagation of solar energetic particles. However, the large-scale field cannot be constructed reliably by currently available observational resources. We assess the potential of high-quality observations from beyond Earth's perspective and advanced global modeling to understand the couplings between coronal events in the context of CMEs and solar energetic particle events.

  12. The onset of large-scale dynamical instability in the Solar System

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin; Holman, Matthew J.; Morbidelli, Alessandro

    2014-05-01

    Over the last two decades, evidence has mounted that the centuries-old question concerning the dynamical stability of the solar system has a straight-forward, definitive answer: with a probability of ~1%, the inner solar system may gravitationally unravel on a timescale comparable to the remaining main-sequence lifetime of the Sun. Concurrently, as the orbital distribution of extrasolar planets began to surface, it had become clear that dynamical instability is a generic process that plays a central role in shaping the architecture of planetary systems. Despite its inherent significance, an unembellished qualitative description of the onset of orbital disorder is largely missing. In this work, we will describe a purely analytical theory for the chaotic disintegration of planetary systems. Specifically, with an emphasis on the Solar System, we will delineate a perturbative model that broadly captures the onset of large-scale instability and use it to elucidate the source of Mercury's chaotic behavior, as well as estimate the corresponding Lyapunov and diffusion coefficients. Subsequently, we will present a framework for calculating the characteristic dynamical lifetime of the inner Solar System. The obtained results constitute an important step towards developing an intuitive view of the long-term evolution of planetary systems.

  13. The structure of the white-light corona and the large-scale solar magnetic field

    NASA Technical Reports Server (NTRS)

    Sime, D. G.; Mccabe, M. K.

    1990-01-01

    The large-scale density structure of the white-light solar corona is compared to the organization of the solar magnetic field as identified by the appearance of neutral lines in the photosphere to examine whether any consistent relationship exists between the two. During the period covering Carrington rotations 1717 to 1736 brightness enhancements in the low corona tend to lie over the global neutral sheet identified in the photospheric magnetic field. The brightest of these enhancements are associated with neutral lines throguh active regions. These associations are not 1-1, but do hold both in stable and evolving conditions of the corona. A significant number of long-lived neutral lines is found, including filaments seen in H-alpha, for which there are not coronal enhancements.

  14. The large-scale magnetic field in the solar wind. [interplanetary magnetic fields/solar activity effects

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Ness, N. F.

    1975-01-01

    A large-scale, three dimensional magnetic field in the interplanetary medium with an expected classical spiral pattern to zeroth order is discussed. Systematic and random deviations which are expected are treated. The sector structure which should be evident at high latitudes is examined. Interplanetary streams are discussed as determining the patterns of magnetic field intensity. It was proposed that the large-scale spiral field can induce a meridional flow which might alter the field geometry somewhat. The nonuniformities caused by streams will probably significantly influence the motion of solar and galactic particles. It was concluded that knowledge of the 3-dimensional field and its dynamical effects can be obtained by in situ measurements by a probe which goes over the sun's poles. Diagrams of the magnetic fields are given.

  15. Dynamics of the Polar Cusps for Active Solar Wind Conditions: Large-scale Modeling

    NASA Astrophysics Data System (ADS)

    Berchem, J.; Richard, R. L.; Escoubet, C. P.; Taylor, M. G.; Laakso, H. E.; Masson, A.; Dandouras, I. S.; Reme, H.; Pitout, F.; Lucek, E. A.

    2010-12-01

    The energy-latitude dispersion of precipitating particles observed by spacecraft near the high-latitude dayside magnetosphere offers a unique opportunity to investigate the large-scale topology and dynamics of the polar cusps. In particular, consecutive crossings of the cusps made by the Cluster spacecraft in a string of pearl configuration are particularly well suited for investigating the temporal and spatial evolution of precipitating particles as solar wind discontinuities interact with the dayside magnetopause. We present the results of large-scale simulation studies based on Cluster observations of ion dispersions following rapid changes in the direction of the interplanetary magnetic field (IMF). First, we use three-dimensional magnetohydrodynamic (MHD) simulations to follow the evolution of the global topology of the magnetic field during the events. Subsequently, the time-dependent electric and magnetic fields predicted by the MHD simulations are utilized to compute the trajectories of large samples of solar wind ions launched upstream of the bow shock. We assess the results of the studies by comparing Cluster ion measurements with ion dispersions calculated from the simulations along the spacecraft trajectories and discuss the temporal evolution and spatial extent of precipitating particles in the context of the reconnection process at the dayside magnetopause.

  16. Link between local scale BC emissions and large scale atmospheric solar absorption

    NASA Astrophysics Data System (ADS)

    Praveen, P. S.; Ahmed, T.; Kar, A.; Rehman, I. H.; Ramanathan, V.

    2011-07-01

    Project Surya has documented indoor and outdoor concentrations of black carbon (BC) from traditional biomass burning cook stoves in a rural village located in the Indo-Gangetic Plains (IGP) region of N. India from November 2009- September 2010. In this paper, we systematically document the link between local scale aerosol properties and column averaged regional aerosol optical properties and atmospheric radiative forcing. We report observations from the first phase of Project Surya to estimate the source dependent (biomass and fossil fuels) aerosol optical properties from local to regional scale. Data were collected using surface based observations of BC, organic carbon (OC), aerosol light absorption, scattering coefficient at the Surya village (SVI_1) located in IGP region, and satellite and AERONET observations at the regional scale (IGP). The daily mean BC concentrations at SVI1 showed the large increase of BC during the dry season (December to February) with values reaching 35 μg m-3. Space based LIDAR data reveal how the biomass smoke is trapped within the first kilometre during the dry season and its extension to above 5 km during the pre-monsoon season. As a result during the dry season, the variance in the daily mean SSA and column aerosol optical properties at the local IGP site correlated (with slopes in the range of 0.85 to 1.06 and R2>0.4) well with the "IGP_AERONET" (mean of six AERONET sites), thus suggesting in-situ observations at few locations can be used to infer spatial mean forcing. The atmospheric forcing due to BC and OC exceeded 20 W m-2 during all months from November to May, leading to the deduction that elimination of cook stove smoke emissions through clean cooking technologies will likely have a major positive impact on health and the regional climate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  18. Detection of large scale geomagnetic pulsations by MAGDAS-egypt stations during the solar minimum of the solar cycle 24

    NASA Astrophysics Data System (ADS)

    Fathy, Ibrahim

    2016-07-01

    This paper presents a statistical study of different types of large-scale geomagnetic pulsation (Pc3, Pc4, Pc5 and Pi2) detected simultaneously by two MAGDAS stations located at Fayum (Geo. Coordinates 29.18 N and 30.50 E) and Aswan (Geo. Coordinates 23.59 N and 32.51 E) in Egypt. The second order butter-worth band-pass filter has been used to filter and analyze the horizontal H-component of the geomagnetic field in one-second data. The data was collected during the solar minimum of the current solar cycle 24. We list the most energetic pulsations detected by the two stations instantaneously, in addition; the average amplitude of the pulsation signals was calculated.

  19. Large-scale interaction of the solar wind with comets Halley and Giacobini-Zinner

    NASA Technical Reports Server (NTRS)

    Brandt, John C.; Niedner, Malcolm B., Jr.

    1987-01-01

    In-situ measurements of comets Halley and Giacobini-Zinner have confirmed the accepted basic physics of comet/solar wind interaction. The solar wind magnetic field is captured by the comet through the mechanism of field-line loading by cometary ions and the field lines drape around the cometary ionosphere. With this basic model in hand, the large-scale structure of the plasma tail as revealed by submissions to the Large Scale Phenomena Network of the International Halley Watch is reviewed. The turn-on and turn-off of plasma activity seem consistent with theory. Some 16 obvious disconnection events (DEs) have been recorded. Preliminary results showed agreement with the sector-boundary model; a detailed analysis of all DEs will be required in order to make a definitive statement. A study of plasma activity around the time of the VEGA encounters provides strong support for the sector-boundary model and illustrates once again the power of simultaneous remote and in-situ measurements.

  20. Effects of Large-scale Non-axisymmetric Perturbations in the Mean-field Solar Dynamo.

    NASA Astrophysics Data System (ADS)

    Pipin, V. V.; Kosovichev, A. G.

    2015-11-01

    We explore the response of a nonlinear non-axisymmetric mean-field solar dynamo model to shallow non-axisymmetric perturbations. After a relaxation period, the amplitude of the non-axisymmetric field depends on the initial condition, helicity conservation, and the depth of perturbation. It is found that a perturbation that is anchored at 0.9 R⊙ has a profound effect on the dynamo process, producing a transient magnetic cycle of the axisymmetric magnetic field, if it is initiated at the growing phase of the cycle. The non-symmetric, with respect to the equator, perturbation results in a hemispheric asymmetry of the magnetic activity. The evolution of the axisymmetric and non-axisymmetric fields depends on the turbulent magnetic Reynolds number Rm. In the range of Rm = 104-106 the evolution returns to the normal course in the next cycle, in which the non-axisymmetric field is generated due to a nonlinear α-effect and magnetic buoyancy. In the stationary state, the large-scale magnetic field demonstrates a phenomenon of “active longitudes” with cyclic 180° “flip-flop” changes of the large-scale magnetic field orientation. The flip-flop effect is known from observations of solar and stellar magnetic cycles. However, this effect disappears in the model, which includes the meridional circulation pattern determined by helioseismology. The rotation rate of the non-axisymmetric field components varies during the relaxation period and carries important information about the dynamo process.

  1. CURRENT HELICITY OF ACTIVE REGIONS AS A TRACER OF LARGE-SCALE SOLAR MAGNETIC HELICITY

    SciTech Connect

    Zhang, H.; Gao, Y.; Xu, H.; Moss, D.; Kleeorin, N.; Rogachevskii, I.; Kuzanyan, K.; Sokoloff, D.

    2012-05-20

    We demonstrate that the current helicity observed in solar active regions traces the magnetic helicity of the large-scale dynamo generated field. We use an advanced two-dimensional mean-field dynamo model with dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic two-dimensional mean-field dynamo model with simple algebraic alpha-quenching only. Using these numerical models we obtained butterfly diagrams both for the small-scale current helicity and also for the large-scale magnetic helicity, and compared them with the butterfly diagram for the current helicity in active regions obtained from observations. This comparison shows that the current helicity of active regions, as estimated by -A {center_dot} B evaluated at the depth from which the active region arises, resembles the observational data much better than the small-scale current helicity calculated directly from the helicity evolution equation. Here B and A are, respectively, the dynamo generated mean magnetic field and its vector potential. A theoretical interpretation of these results is given.

  2. Solar Wind and IMF Control of Large-Scale Ionospheric Currents and Their Time Variations

    NASA Astrophysics Data System (ADS)

    Juusola, L.; Kauristie, K.; Tanskanen, E.; Partamies, N.; Viljanen, A.; Andréeová, K.; van de Kamp, M.; Vanhamäki, H.; Milan, S. E.; Lester, M.; Grocott, A.; Imber, S. M.

    2014-12-01

    Patterns of high-latitude ionospheric currents are a manifestation of the solar wind-magnetosphere-ionosphere coupling. Rapid variations of the currents are associated with geomagnetically induced currents (GIC) in technological conductor systems and displays of bright, diverse auroras. One advantage of a ground-based magnetometer network over a low-orbit satellite is the possibility to distinguish between temporal and spatial variations in the data. Although ground magnetic field data can only yield distributions of ionospheric equivalent currents instead of the full horizontal and field-aligned current density, estimates for these can be obtained, under certain assumptions. We use data (1994-2013) from the ground-based IMAGE magnetometer network to derive statistical distributions of the large-scale ionospheric equivalent current density and its time-derivative as well as estimates for the field-aligned current density. These are compared with and validated against horizontal and field-aligned current density distributions obtained from low-orbit CHAMP satellite magnetic field data (2000-2010) and convection maps obtained from SuperDARN radar data (2000-2010). The ground-based distributions reveal a strong dependence of the dayside variations on radial interplanetary magnetic field (IMF) orientation and solar wind speed. The spatial distribution of enhanced nightside activity agrees with that of the average substorm bulge and depends on solar wind energy input into the magnetosphere. The most intense time variation events are related to substorm activity and occur on the nightside.

  3. Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Riley, Pete

    2001-01-01

    This investigation is concerned with the large-scale evolution and topology of coronal mass ejections (CMEs) in the solar wind. During the course of this three-year investigation, we have undertaken a number of studies that are discussed in more detail in this report. For example, we conducted an analysis of all CMEs observed by the Ulysses spacecraft during its in-ecliptic phase between 1 and 5 AU. In addition to studying the properties of the ejecta, we also analyzed the shocks that could be unambiguously associated with the fast CMEs. We also analyzed a series of 'density holes' observed in the solar wind that bear many similarities with CMEs. To complement this analysis, we conducted a series of 1-D and 2 1/2-D fluid, MHD, and hybrid simulations to address a number of specific issues related to CME evolution in the solar wind. For example, we used fluid simulations to address the interpretation of negative electron temperature-density relationships often observed within CME/cloud intervals. As part of this investigation, a number of fruitful international collaborations were forged. Finally, the results of this work were presented at nine scientific meetings and communicated in eight scientific, refereed papers.

  4. Large-Scale Activity in the Bastille Day 2000 Solar Event

    NASA Astrophysics Data System (ADS)

    Chertok, I. M.; Grechnev, V. V.

    2005-06-01

    We have analyzed dimmings, i.e., regions of temporarily reduced brightness, and manifestations of a coronal wave in the famous event of 14 July 2000 using images produced with the EUV telescope SOHO/EIT. Our analysis was inspired by a paper by Andrews (2001, Solar Phys. 204, 181 (Paper I)), in which this event was studied using running-difference EIT images at 195 Å formed by subtraction of a previous image from each current one. Such images emphasize changes of the brightness, location, and configuration of observed structures occurring during the 12-min interval between two subsequent heliograms. However, they distort the picture of large-scale disturbances caused by a CME, particularly, dimmings. A real picture of dimmings can be obtained from fixed-base difference ‘de-rotated’ images. The latter are formed in two stages: first, the solar rotation is compensated using three-dimensional rotation of all images (‘de-rotation’) to the time of a pre-event heliogram, here 10:00 UT, and then the base heliogram is subtracted from all others. We show real dimmings to be essentially different from those described by Andrews (Paper I). The restructuring of large-scale magnetic fields in the corona in connection with the CME was accompanied by the appearance and growth of two large dimmings. One of them was located along the central meridian, southward of the eruption center, at the place of the pre-eruption arcade. Another dimming occupied the space between the flare region and a remote western active region. Several smaller dimmings were observed virtually over the whole solar disk, especially, within the northwest quadrant. We have also revealed a propagating disturbance with properties of a coronal wave in the northern polar sector, where no dimmings were observed. This fact is discussed in the context of probable association between dimmings and coronal waves. Having suppressed the ‘snowstorm’ produced in the EIT images by energetic particles, we have

  5. Coronal holes, large-scale magnetic field, and activity complexes in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Tavastsherna, K. S.; Polyakow, E. V.

    2014-12-01

    A correlation among coronal holes (CH), a large-scale magnetic field (LMF), and activity complexes (AC) is studied in this work for 1997-2007 with the use of a coronal hole series obtained from observations at the Kitt Peak Observatory in the HeI 10830 Å line in 1975-2003 and SOHO/EIT-195 Å in 1996-2012 (Tlatov et al., 2014), synoptic Hα charts from Kislovodsk Mountain Astonomical Station, and the catalog of AC cores (Yazev, 2012). From the imposition of CH boundaries on Hα charts, which characterize the positions of neutral lines of the radial components of a large-scale solar magnetic field, it turns out that 70% of CH are located in unipolar regions of their sign during the above period, 10% are in the region of an opposite sign, and 20% are mainly very large CH, which are often crossed by the neutral lines of several unipolar regions. Data on mutual arrangement of CH and AC cores were obtained. It was shown that only some activity comples cores have genetic relationships with CH.

  6. Large-scale Coronal Propagating Fronts During the Rising Phase of Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Nitta, N. V.; Liu, W.; Schrijver, C. J.; Title, A. M.; Lemen, J. R.

    2011-12-01

    With increasing solar activity, the AIA on SDO has observed a number of large-scale coronal propagating fronts, which are often called "EIT waves." Although their nature is still actively debated, these propagating fronts usually accompany CMEs, and, in certain cases, may signify CME-related shock waves important for particle acceleration. Using the unprecedented temporal resolution and broad temperature coverage of the AIA, it is possible to characterize the propagating fronts in the corona far better than before, as demonstrated in the literature for a yet small number of cases. We study the properties of more than 40 propagating fronts as observed by AIA, and discuss the key properties for them to be associated with other phenomena such as type II radio bursts, flares, CMEs, ICMEs, and SEP events. We make use of data, both remote-sensing and in-situ, from STEREO which provides two additional vantage points, to make the associations more solid. For the associated phenomena, their basic properties are correlated with those of the propagating fronts. We also revisit the association of EIT waves with other phenomena during the similar phase of Solar Cycle 23 and discuss possible differences in terms of global magnetic field. Understanding their relation with other phenomena, we can have a more complete picture of the coronal propagating fronts in the context of CME acceleration and deceleration.

  7. Large-scale Bright Fronts in the Solar Corona: A Review of "EIT waves"

    NASA Astrophysics Data System (ADS)

    Gallagher, Peter T.; Long, David M.

    2011-07-01

    "EIT waves" are large-scale coronal bright fronts (CBFs) that were first observed in 195 Å images obtained using the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory ( SOHO). Commonly called "EIT waves", CBFs typically appear as diffuse fronts that propagate pseudo-radially across the solar disk at velocities of 100-700 km s-1 with front widths of 50-100 Mm. As their speed is greater than the quiet coronal sound speed ( c s ≤200 km s-1) and comparable to the local Alfvén speed ( v A ≤1000 km s-1), they were initially interpreted as fast-mode magnetoacoustic waves (vf=(cs2 + vA2)^{1/2}). Their propagation is now known to be modified by regions where the magnetosonic sound speed varies, such as active regions and coronal holes, but there is also evidence for stationary CBFs at coronal hole boundaries. The latter has led to the suggestion that they may be a manifestation of a processes such as Joule heating or magnetic reconnection, rather than a wave-related phenomena. While the general morphological and kinematic properties of CBFs and their association with coronal mass ejections have now been well described, there are many questions regarding their excitation and propagation. In particular, the theoretical interpretation of these enigmatic events as magnetohydrodynamic waves or due to changes in magnetic topology remains the topic of much debate.

  8. Coronal and Chromospheric Signatures of Large-scale Disturbances Associated with a Major Solar Eruption

    NASA Astrophysics Data System (ADS)

    Zong, Weiguo; Dai, Yu

    2015-08-01

    We present both coronal and chromospheric observations of large-scale disturbances associated with a major solar eruption on 2005 September 7. In the Geostationary Operational Environmental Satellites/Solar X-ray Imager (SXI), arclike coronal brightenings are recorded propagating in the southern hemisphere. The SXI front shows an initially constant speed of 730 km s-1 and decelerates later on, and its center is near the central position angle of the associated coronal mass ejection (CME) but away from the flare site. Chromospheric signatures of the disturbances are observed in both Mauna Loa Solar Observatory (MLSO)/Polarimeter for Inner Coronal Studies Hα and MLSO/Chromospheric Helium I Imaging Photometer He i λ10830 and can be divided into two parts. The southern signatures occur in regions where the SXI front sweeps over, with the Hα bright front coincident with the SXI front, while the He i dark front lags the SXI front but shows a similar kinematics. Ahead of the path of the southern signatures, oscillations of a filament are observed. The northern signatures occur near the equator, with the Hα and He i fronts coincident with each other. They first propagate westward and then deflect to the north at the boundary of an equatorial coronal hole. Based on these observational facts, we suggest that the global disturbances are associated with the CME lift-off and show a hybrid nature: a mainly non-wave CME flank nature for the SXI signatures and the corresponding southern chromospheric signatures, and a shocked fast-mode coronal MHD wave nature for the northern chromospheric signatures.

  9. Heating of the solar middle chromosphere by large-scale electric currents

    NASA Technical Reports Server (NTRS)

    Goodman, M. L.

    1995-01-01

    A global resistive, two-dimensional, time-dependent magnetohydrodynamic (MHD) model is used to introduce and support the hypothesis that the quiet solar middle chromosphere is heated by resistive dissipation of large-scale electric currents which fill most of its volume. The scale height and maximum magnitude of the current density are 400 km and 31.3 m/sq m, respectively. The associated magnetic field is almost horizontal, has the same scale height as the current density, and has a maximum magnitude of 153 G. The current is carried by electrons flowing across magnetic field lines at 1 m/s. The resistivity is the electron contribution to the Pedersen resitivity for a weakly ionized, strongly magnetized, hydrogen gas. The model does not include a driving mechanism. Most of the physical quantities in the model decrease exponentially with time on a resistive timescale of 41.3 minutes. However, the initial values and spatial; dependence of these quantities are expected to be essentially the same as they would be if the correct driving mechanism were included in a more general model. The heating rate per unit mass is found to be 4.5 x 10(exp 9) ergs/g/s, independent of height and latitude. The electron density scale height is found to be 800 km. The model predicts that 90% of the thermal energy required to heat the middle chromosphere is deposited in the height range 300-760 km above the temperature minimum. It is shown to be consistent to assume that the radiation rate per unit volume is proportional to the magnetic energy density, and then it follows that the heating rate per unit volume is also proportional to the energy from the photosphere into the overlying chromosphere are briefly discussed as possible driving mechanisms for establishing and maintaining the current system. The case in which part of or all of the current is carried by protons and metal ions, and the contribution of electron-proton scattering to the current are also considered, with the conclusion

  10. Formation and Evolution of Large-Scale Magnetic Funnels in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Panasenco, Olga; Velli, Marco

    2016-05-01

    The existence of open coronal magnetic fields with peculiar geometry - large-scale magnetic funnels - can be attributed to three factors: (i) the presence of two or more corona holes of the same polarity (or pseudostreamers - PSs), (ii) specific configurations of closed magnetic field in the low corona up to 1.3 Rs (filament channels) and (iii) the presence of strong active regions in the vicinity of the pseudostreamer. The important property of magnetic funnels is their strongly non-monotonic expansion factor below 2 Rs. The case study presented here is a pseudostreamer near the equator, formed between two isolated coronal holes of the same polarity, and harboring a pair of twin filaments in its base. Following the evolution of these coronal holes we find that the PS topology changes when two coronal holes merged together. Using a potential field source-surface (PFSS) extrapolation to compute the coronal field from photospheric maps (SDO/HMI), we show that the funnel-like geometry of the open magnetic field changes to a regular one with monotonic expansion factor after the merging of coronal holes. The presence of coronal magnetic funnels becomes directly visible when sufficient plasma accumulates inside them: when the plasma density grows to become observable coronal cloud prominences appear in the corona. The plasma suspension at heights of 0.3 Rs coincides with the largest gradients in the field which naturally leads to a diamagnetic hypothesis for the force counteracting gravity. We study the evolution of the funnel-like open fields during several solar rotations and find a direct relation between funnels and the presence of coronal clouds at great heights in the solar corona.

  11. Large-scale properties of the solar wind in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Khabarova, Olga; Obridko, Vladimir; Zharkova, Valentina; Veselov, Mikhail

    Since the solar wind phenomenon has been revealed and confirmed, one of the most intriguing problems was to understand processes in the solar atmosphere and their relation with the solar wind characteristics at different distances from the Sun. Analysis of multi-spacecraft measurements of plasma parameters and the interplanetary magnetic field provides us with knowledge about the heliosphere from global to small scales. Comparisons of observations with models, describing small-scale processes, usually give more positive results than in the case of models comparison with the solar wind properties at the scales larger than several proton gyroradii. For example, Parker-like models face with big problems in their attempts to predict the solar wind plasma and, especially, the behaviour of the interplanetary magnetic field. Observations show that the radial component of the interplanetary magnetic field depends on heliolatitude and radially decreases with a slope of -5/3 instead of the predicted slope of -2 (Khabarova, Obridko, ApJ, 2012; Khabarova, Astronomy Reports, 2013). This may be determined by small-scale processes occurring in some vicinity of the heliospheric current sheet and related to the magnetic reconnection (Zharkova, Khabarova, ApJ, 2012). In this report we present results of data analysis of eight spacecraft to study variations of plasma, the electric and magnetic field with distance and heliolatitude. begin{enumerate} Zharkova V., Khabarova O., Particle Acceleration in the Reconnecting Heliospheric Current Sheet: Solar Wind Data Versus 3D PIC Simulations, Astrophysical Journal, 2012, V.752, 1, 35 doi:10.1088/0004-637X/752/1/35 begin{enumerate} Khabarova Olga, and Obridko Vladimir, Puzzles of the Interplanetary Magnetic Field in the Inner Heliosphere, 2012, Astrophysical Journal, 761, 2, 82, doi:10.1088/0004-637X/761/2/82 begin{enumerate} Khabarova Olga V., The interplanetary magnetic field: radial and latitudinal dependences. Astronomy Reports, 2013

  12. An Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Riley, Peter

    2000-01-01

    This investigation is concerned with the large-scale evolution and topology of coronal mass ejections (CMEs) in the solar wind. During this reporting period we have focused on several aspects of CME properties, their identification and their evolution in the solar wind. The work included both analysis of Ulysses and ACE observations as well as fluid and magnetohydrodynamic simulations. In addition, we analyzed a series of "density holes" observed in the solar wind, that bear many similarities with CMEs. Finally, this work was communicated to the scientific community at three meetings and has led to three scientific papers that are in various stages of review.

  13. Effects of large scale integration of wind and solar energy in Japan

    NASA Astrophysics Data System (ADS)

    Esteban, Miguel; Zhang, Qi; Utama, Agya; Tezuka, Tetsuo; Ishihara, Keiichi

    2010-05-01

    results for the country as a whole are considered it is still substantial. The results are greatly dependant on the mix between the proposed renewables (solar and wind), and by comparing different distributions and mixes, the optimum composition for the target country can be established. The methodology proposed is able to obtain the optimum mix of solar and wind power for a given system, provided that adequate storage capacity exists to allow for excess capacity to be used at times of low electricity production (at the comparatively rare times when there is neither enough sun nor wind throughout the country). This highlights the challenges of large-scale integration of renewable technologies into the electricity grid, and the necessity to combine such a system with other renewables such as hydro or ocean energy to further even out the peaks and lows in the demand.

  14. Large Scale Thermal Events in the Solar Nebula Recorded in FeNi Metal Condensates in CH Chondrites

    NASA Technical Reports Server (NTRS)

    Meibom, A.; Desch, S. J.; Krot, A. N.; Cuzzi, J. N.; Petaev, M. I.; Wilson, L.; Keil, K.

    2000-01-01

    Some FeNi metal grains in CHs formed by gas-solid condensation from a gas of solar composition cooling at approx. 0.2 K/h from approx. 1370 K to approx. 1270 K. An astrophysical setting is proposed, which involves large scale convective updrafts from the disk midplane.

  15. The absorption chiller in large scale solar pond cooling design with condenser heat rejection in the upper convecting zone

    SciTech Connect

    Tsilingiris, P.T. )

    1992-07-01

    The possibility of using solar ponds as low-cost solar collectors combined with commercial absorption chillers in large scale solar cooling design is investigated. The analysis is based on the combination of a steady-state solar pond mathematical model with the operational characteristics of a commercial absorption chiller, assuming condenser heat rejection in the upper convecting zone (U.C.Z.). The numerical solution of the nonlinear equations involved leads to results which relate the chiller capacity with pond design and environmental parameters, which are also employed for the investigation of the optimum pond size for a minimum capital cost. The derived cost per cooling kW for a 350 kW chiller ranges from about 300 to 500 $/kW cooling. This is almost an order of magnitude lower than using a solar collector field of evacuated tube type.

  16. Continuous Flow Polymer Synthesis toward Reproducible Large-Scale Production for Efficient Bulk Heterojunction Organic Solar Cells.

    PubMed

    Pirotte, Geert; Kesters, Jurgen; Verstappen, Pieter; Govaerts, Sanne; Manca, Jean; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter

    2015-10-12

    Organic photovoltaics (OPV) have attracted great interest as a solar cell technology with appealing mechanical, aesthetical, and economies-of-scale features. To drive OPV toward economic viability, low-cost, large-scale module production has to be realized in combination with increased top-quality material availability and minimal batch-to-batch variation. To this extent, continuous flow chemistry can serve as a powerful tool. In this contribution, a flow protocol is optimized for the high performance benzodithiophene-thienopyrroledione copolymer PBDTTPD and the material quality is probed through systematic solar-cell evaluation. A stepwise approach is adopted to turn the batch process into a reproducible and scalable continuous flow procedure. Solar cell devices fabricated using the obtained polymer batches deliver an average power conversion efficiency of 7.2 %. Upon incorporation of an ionic polythiophene-based cathodic interlayer, the photovoltaic performance could be enhanced to a maximum efficiency of 9.1 %. PMID:26388210

  17. Large-scale flows and magnetic fields in solar-like stars from global simulation with and without tachocline

    NASA Astrophysics Data System (ADS)

    Guerrero, G.; Kosovichev, A. G.; Smolarkiewicz, P. K.; de Gouveia Dal Pino, E. M.

    2014-12-01

    The large-scale flows patterns like differential rotation and meridional circulation as well as the mean-field dynamo action in the Sun and solar-like stars are thought to have their origin in helical turbulent motions in the stellar convection zones. In this work we will present recent results of HD and MHD global simulations of stars whose stratification resemble that of the solar interior. The simulations are performed with the EULAG code (Smolarkiewicz et al. 2001). They include implicit modeling of the large-eddy contribution from the turbulent scales to the resolved scales, thus, allowing higher turbulent levels (e.g., Guerrero et al. 2013). In the HD regime, the value of the Rossby (Ro) number defines large-scale flow patterns. Large values of Ro result in an anti-solar differential rotation and a meridional circulation consistent with a single circulation cell per hemisphere. Lower values of Ro result in a solar-type differential rotation and a meridional flow with multiple cells in radius and latitude. Due to the low dissipation of the numerical scheme, the models are also able to reproduce the tachocline and sustain it over a longer time scale. In the MHD regime, both solutions are still allowed, however, the shift from anti-solar to the solar-like rotation happens at a larger value or Ro. A wide range of dynamo solutions is obtained for the magnetic field, including steady and oscillating modes (see e.g., Fig. 1). We also compare models with and without a stable stratified layer at the bottom of the convection zone. We notice that the presence of a naturally developed tachocline plays an important role in the dynamo solution, modifying the morphology of the magnetic field, the cycles period and influencing the large-scale flows.References:Smolarkiewicz, P. K., Margolin, L. G., & Wyszogrodzki, A. A. 2001, JAtS, 58, 349; Guerrero, G., Smolarkiewicz, P. K., Kosovichev, A.K., Mansour, N.N. 2013, ApJ, 779, 176.

  18. ERRATUM: Correlations at Large Scales and the Onset of Turbulence in the Fast Solar Wind

    NASA Technical Reports Server (NTRS)

    Wicks, R. T.; Roberts, D. A.; Mallet, A.; Schekochihin, A. A.; Horbury, T. S.; Chen, C. H. K.

    2014-01-01

    We show that the scaling of structure functions of magnetic and velocity fields in a mostly highly Alfvenic fast solar wind stream depends strongly on the joint distribution of the dimensionless measures of cross helicity and residual energy. Already at very low frequencies, fluctuations that are both more balanced (cross helicity approx. 0) and equipartitioned (residual energy approx.0) have steep structure functions reminiscent of "turbulent" scalings usually associated with the inertial range. Fluctuations that are magnetically dominated (residual energy approx. –1), and so have closely anti-aligned Elsasser-field vectors, or are imbalanced (cross helicity approx. 1), and so have closely aligned magnetic and velocity vectors, have wide "1/f" ranges typical of fast solar wind. We conclude that the strength of nonlinear interactions of individual fluctuations within a stream, diagnosed by the degree of correlation in direction and magnitude of magnetic and velocity fluctuations, determines the extent of the 1/f region observed, and thus the onset scale for the turbulent cascade.

  19. Correlations at large scales and the onset of turbulence in the fast solar wind

    SciTech Connect

    Wicks, R. T.; Roberts, D. A.; Mallet, A.; Schekochihin, A. A.; Horbury, T. S.; Chen, C. H. K.

    2013-12-01

    We show that the scaling of structure functions of magnetic and velocity fields in a mostly highly Alfvénic fast solar wind stream depends strongly on the joint distribution of the dimensionless measures of cross helicity and residual energy. Already at very low frequencies, fluctuations that are both more balanced (cross helicity ∼0) and equipartitioned (residual energy ∼0) have steep structure functions reminiscent of 'turbulent' scalings usually associated with the inertial range. Fluctuations that are magnetically dominated (residual energy ∼–1), and so have closely anti-aligned Elsasser-field vectors, or are imbalanced (cross helicity ∼1), and so have closely aligned magnetic and velocity vectors, have wide '1/f' ranges typical of fast solar wind. We conclude that the strength of nonlinear interactions of individual fluctuations within a stream, diagnosed by the degree of correlation in direction and magnitude of magnetic and velocity fluctuations, determines the extent of the 1/f region observed, and thus the onset scale for the turbulent cascade.

  20. SWAP OBSERVATIONS OF THE LONG-TERM, LARGE-SCALE EVOLUTION OF THE EXTREME-ULTRAVIOLET SOLAR CORONA

    SciTech Connect

    Seaton, Daniel B.; De Groof, Anik; Berghmans, David; Nicula, Bogdan; Shearer, Paul

    2013-11-01

    The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar telescope on board the Project for On-Board Autonomy 2 spacecraft has been regularly observing the solar corona in a bandpass near 17.4 nm since 2010 February. With a field of view of 54 × 54 arcmin, SWAP provides the widest-field images of the EUV corona available from the perspective of the Earth. By carefully processing and combining multiple SWAP images, it is possible to produce low-noise composites that reveal the structure of the EUV corona to relatively large heights. A particularly important step in this processing was to remove instrumental stray light from the images by determining and deconvolving SWAP's point-spread function from the observations. In this paper, we use the resulting images to conduct the first-ever study of the evolution of the large-scale structure of the corona observed in the EUV over a three year period that includes the complete rise phase of solar cycle 24. Of particular note is the persistence over many solar rotations of bright, diffuse features composed of open magnetic fields that overlie polar crown filaments and extend to large heights above the solar surface. These features appear to be related to coronal fans, which have previously been observed in white-light coronagraph images and, at low heights, in the EUV. We also discuss the evolution of the corona at different heights above the solar surface and the evolution of the corona over the course of the solar cycle by hemisphere.

  1. SWAP Observations of the Long-term, Large-scale Evolution of the Extreme-ultraviolet Solar Corona

    NASA Astrophysics Data System (ADS)

    Seaton, Daniel B.; De Groof, Anik; Shearer, Paul; Berghmans, David; Nicula, Bogdan

    2013-11-01

    The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar telescope on board the Project for On-Board Autonomy 2 spacecraft has been regularly observing the solar corona in a bandpass near 17.4 nm since 2010 February. With a field of view of 54 × 54 arcmin, SWAP provides the widest-field images of the EUV corona available from the perspective of the Earth. By carefully processing and combining multiple SWAP images, it is possible to produce low-noise composites that reveal the structure of the EUV corona to relatively large heights. A particularly important step in this processing was to remove instrumental stray light from the images by determining and deconvolving SWAP's point-spread function from the observations. In this paper, we use the resulting images to conduct the first-ever study of the evolution of the large-scale structure of the corona observed in the EUV over a three year period that includes the complete rise phase of solar cycle 24. Of particular note is the persistence over many solar rotations of bright, diffuse features composed of open magnetic fields that overlie polar crown filaments and extend to large heights above the solar surface. These features appear to be related to coronal fans, which have previously been observed in white-light coronagraph images and, at low heights, in the EUV. We also discuss the evolution of the corona at different heights above the solar surface and the evolution of the corona over the course of the solar cycle by hemisphere.

  2. Attribution of ionospheric vertical plasma drift perturbations to large-scale waves and the dependence on solar activity (Invited)

    NASA Astrophysics Data System (ADS)

    Liu, H.; Richmond, A. D.

    2013-12-01

    In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, we calculate equatorial vertical ExB drifts due to mean winds and DW1, SW2, SW1 and QSPW1. In particular, wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

  3. Radial variations of large-scale magnetohydrodynamic fluctuations in the solar wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Goldstein, M. L.

    1983-01-01

    Two time periods are studied for which comprehensive data coverage is available at both 1 AU using IMP-8 and ISEE-3 and beyond using Voyager 1. One of these periods is characterized by the predominance of corotating stream interactions. Relatively small scale transient flows characterize the second period. The evolution of these flows with heliocentric distance is studied using power spectral techniques. The evolution of the transient dominated period is consistent with the hypothesis of turbulent evolution including an inverse cascade of large scales. The evolution of the corotating period is consistent with the entrainment of slow streams by faster streams in a deterministic model.

  4. The concentration of the large-scale solar magnetic field by a meridional surface flow

    NASA Technical Reports Server (NTRS)

    Devore, C. R.; Boris, J. P.; Sheeley, N. R., Jr.

    1984-01-01

    Analytical and numerical solutions to the magnetic flux transport equation in the absence of new bipolar sources of flux are calculated for several meridional flow profiles and a range of peak flow speeds. It is found that a poleward flow with a broad profile and a nominal 10 m/s maximum speed concentrates the large-scale field into very small caps of less than 15 deg half-angle, with average field strengths of several tens of gauss, contrary to observations. A flow which reaches its peak speed at a relatively low latitude and then decreases rapidly to zero at higher latitudes leads to a large-scale field pattern which is consistent with observations. For such a flow, only lower latitude sunspot groups can contribute to interhemispheric flux annihilation and the resulting decay and reversal of the polar magnetic fields.

  5. High-efficiency nanostructured silicon solar cells on a large scale realized through the suppression of recombination channels.

    PubMed

    Zhong, Sihua; Huang, Zengguang; Lin, Xingxing; Zeng, Yang; Ma, Yechi; Shen, Wenzhong

    2015-01-21

    Nanostructured silicon solar cells show great potential for new-generation photovoltaics due to their ability to approach ideal light-trapping. However, the nanofeatured morphology that brings about the optical benefits also introduces new recombination channels, and severe deterioration in the electrical performance even outweighs the gain in optics in most attempts. This Research News article aims to review the recent progress in the suppression of carrier recombination in silicon nanostructures, with the emphasis on the optimization of surface morphology and controllable nanostructure height and emitter doping concentration, as well as application of dielectric passivation coatings, providing design rules to realize high-efficiency nanostructured silicon solar cells on a large scale. PMID:25205286

  6. SIMULTANEOUS OBSERVATIONS OF A LARGE-SCALE WAVE EVENT IN THE SOLAR ATMOSPHERE: FROM PHOTOSPHERE TO CORONA

    SciTech Connect

    Shen, Yuandeng; Liu, Yu

    2012-06-20

    For the first time, we report a large-scale wave that was observed simultaneously in the photosphere, chromosphere, transition region, and low corona layers of the solar atmosphere. Using the high temporal and high spatial resolution observations taken by the Solar Magnetic Activity Research Telescope at Hida Observatory and the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory, we find that the wave evolved synchronously at different heights of the solar atmosphere, and it propagated at a speed of 605 km s{sup -1} and showed a significant deceleration (-424 m s{sup -2}) in the extreme-ultraviolet (EUV) observations. During the initial stage, the wave speed in the EUV observations was 1000 km s{sup -1}, similar to those measured from the AIA 1700 A (967 km s{sup -1}) and 1600 A (893 km s{sup -1}) observations. The wave was reflected by a remote region with open fields, and a slower wave-like feature at a speed of 220 km s{sup -1} was also identified following the primary fast wave. In addition, a type-II radio burst was observed to be associated with the wave. We conclude that this wave should be a fast magnetosonic shock wave, which was first driven by the associated coronal mass ejection and then propagated freely in the corona. As the shock wave propagated, its legs swept the solar surface and thereby resulted in the wave signatures observed in the lower layers of the solar atmosphere. The slower wave-like structure following the primary wave was probably caused by the reconfiguration of the low coronal magnetic fields, as predicted in the field-line stretching model.

  7. Large-scale and Long-duration Simulation of a Multi-stage Eruptive Solar Event

    NASA Astrophysics Data System (ADS)

    Jiang, chaowei; Hu, Qiang; Wu, S. T.

    2015-04-01

    We employ a data-driven 3D MHD active region evolution model by using the Conservation Element and Solution Element (CESE) numerical method. This newly developed model retains the full MHD effects, allowing time-dependent boundary conditions and time evolution studies. The time-dependent simulation is driven by measured vector magnetograms and the method of MHD characteristics on the bottom boundary. We have applied the model to investigate the coronal magnetic field evolution of AR11283 which was characterized by a pre-existing sigmoid structure in the core region and multiple eruptions, both in relatively small and large scales. We have succeeded in producing the core magnetic field structure and the subsequent eruptions of flux-rope structures (see https://dl.dropboxusercontent.com/u/96898685/large.mp4 for an animation) as the measured vector magnetograms on the bottom boundary evolve in time with constant flux emergence. The whole process, lasting for about an hour in real time, compares well with the corresponding SDO/AIA and coronagraph imaging observations. From these results, we show the capability of the model, largely data-driven, that is able to simulate complex, topological, and highly dynamic active region evolutions. (We acknowledge partial support of NSF grants AGS 1153323 and AGS 1062050, and data support from SDO/HMI and AIA teams).

  8. High-Efficiency Solar Cells for Large-Scale Electricity Generation

    SciTech Connect

    Kurtz, S.; Olson, J.; Geisz, J.; Friedman, D.; McMahon, W.; Ptak, A.; Wanlass, M.; Kibbler, A.; Kramer, C.; Bertness, K.; Ward, S.; Duda, A.; Young, M.; Carapella, J.; Steiner, M.

    2008-09-26

    One strategy for helping the solar industry to grow faster is to use very high efficiency cells under concentrating optics. By using lenses or mirrors to concentrate the light, very small solar cells can be used, reducing the amount of semiconductor material and allowing use of higher efficiency cells, which are now >40% efficient.

  9. The large-scale magnetic field in the solar wind. [astronomical models of interplanetary magnetics and the solar magnetic field

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Ness, N. F.

    1976-01-01

    A literature review is presented of theoretical models of the interaction of the solar wind and interplanetary magnetic fields. Observations of interplanetary magnetic fields by the IMP and OSO spacecraft are discussed. The causes for cosmic ray variations (Forbush decreases) by the solar wind are examined. The model of Parker is emphasized. This model shows the three dimensional magnetic field lines of the solar wind to have the form of spirals wrapped on cones. It is concluded that an out-of-the-ecliptic solar probe mission would allow the testing and verification of the various theoretical models examined. Diagrams of the various models are shown.

  10. A Scintillator Purification System for a Large Scale Solar Neutrino Experiment

    NASA Astrophysics Data System (ADS)

    Benziger, J. B.

    1999-08-01

    An on-line purification system for a large-scale low-background liquid scintillation detector has been tested with the 5-ton liquid scintillation detector, the Counting Test Facility at Gran Sasso. Counter-current water extraction removes polar and charged impurities such as ions and metal salts. Vacuum distillation of the entire scintillator has been applied to remove both radioactive impurities and chemical impurities that affect the optical properties of the scintillator. Filtration with a 0.05 μm particulate filter removed suspended dust particles that may contain U, Th and K. Nitrogen stripping was employed to remove dissolved water and noble gases (e.g. 85Kr) from the scintillator. The system has effectively reduced the internal back in the 5 ton liquid scintillation detector from 470+/-90 events/d to the detection limit of the detector (+/-45 events/d) in the energy window 250

  11. A scintillator purification system for a large scale solar neutrino experiment.

    NASA Astrophysics Data System (ADS)

    Benziger, J. B.; Johnson, M.; Calaprice, F. P.; Chen, M.; Darnton, N.; Loeser, R.; Vogelaar, R. B.

    1998-11-01

    An on-line purification system for a large-scale low-background liquid scintillation detector has been tested with the 5 t liquid scintillation detector, the Counting Test Facility at Gran Sasso. Counter-current water extraction removes polar and charged impurities such as ions and metal salts. Vacuum distillation of the entire scintillator has been applied to remove both radioactive impurities and chemical impurities that affect the optical properties of the scintillator. Filtration with a 0.05 μm particulate filter removed suspended dust particles that may contain U, Th and K. Nitrogen stripping was employed to remove dissolved water and noble gases (e.g. 85Kr) from the scintillator. The system has effectively reduced the internal back in the 5 t liquid scintillation detector from 470±90 events/d to the detection limit of the detector (±45 events/d) in the energy window 250 < E < 800 keV.

  12. Rotation of the Large-Scale Solar Magnetic Fields in the Equatorial Region

    NASA Astrophysics Data System (ADS)

    Latushko, S.

    1996-07-01

    A study is made of the rotation of large-scale magnetic fields using the synoptic maps from the Kitt Peak National Observatory for the time interval 1976 1985. The auto-correlation method and the mass-centers method of magnetic structures was applied to infer mean differential rotation profiles and rotation profiles separately for each magnetic field polarity. It has been found that in both hemispheres the leading polarity rotates faster than the following polarity at all latitudes by about 0.04° day-1. The maximum rotation rate of the leading polarity is reached at about 6° latitude. In the mean profile for both polarities, this brings about two angular velocity maxima at 6° latitudes in both hemispheres. Such a profile appears as to have a ‘dimple’ on the equator.

  13. Variability of Power from Large-Scale Solar Photovoltaic Scenarios in the State of Gujarat: Preprint

    SciTech Connect

    Parsons, B.; Hummon, M.; Cochran, J.; Stoltenberg, B.; Batra, P.; Mehta, B.; Patel, D.

    2014-04-01

    India has ambitious goals for high utilization of variable renewable power from wind and solar, and deployment has been proceeding at a rapid pace. The western state of Gujarat currently has the largest amount of solar generation of any Indian state, with over 855 Megawatts direct current (MWDC). Combined with over 3,240 MW of wind, variable generation renewables comprise nearly 18% of the electric-generating capacity in the state. A new historic 10-kilometer (km) gridded solar radiation data set capturing hourly insolation values for 2002-2011 is available for India. We apply an established method for downscaling hourly irradiance data to one-minute irradiance data at potential PV power production locations for one year, 2006. The objective of this report is to characterize the intra-hour variability of existing and planned photovoltaic solar power generation in the state of Gujarat (a total of 1.9 gigawatts direct current (GWDC)), and of five possible expansion scenarios of solar generation that reflect a range of geographic diversity (each scenario totals 500-1,000 MW of additional solar capacity). The report statistically analyzes one year's worth of power variability data, applied to both the baseline and expansion scenarios, to evaluate diurnal and seasonal power fluctuations, different timescales of variability (e.g., from one to 15 minutes), the magnitude of variability (both total megawatts and relative to installed solar capacity), and the extent to which the variability can be anticipated in advance. The paper also examines how Gujarat Energy Transmission Corporation (GETCO) and the Gujarat State Load Dispatch Centre (SLDC) could make use of the solar variability profiles in grid operations and planning.

  14. Variability of Power from Large-Scale Solar Photovoltaic Scenarios in the State of Gujarat (Presentation)

    SciTech Connect

    Parsons, B.; Hummon, M.; Cochran, J.; Stoltenberg, B.; Batra, P.; Mehta, B.; Patel, D.

    2014-04-01

    India has ambitious goals for high utilization of variable renewable power from wind and solar, and deployment has been proceeding at a rapid pace. The western state of Gujarat currently has the largest amount of solar generation of any Indian state, with over 855 Megawatts direct current (MWDC). Combined with over 3,240 MW of wind, variable generation renewables comprise nearly 18% of the electric-generating capacity in the state. A new historic 10-kilometer (km) gridded solar radiation data set capturing hourly insolation values for 2002-2011 is available for India. We apply an established method for downscaling hourly irradiance data to one-minute irradiance data at potential PV power production locations for one year, 2006. The objective of this report is to characterize the intra-hour variability of existing and planned photovoltaic solar power generation in the state of Gujarat (a total of 1.9 gigawatts direct current (GWDC)), and of five possible expansion scenarios of solar generation that reflect a range of geographic diversity (each scenario totals 500-1,000 MW of additional solar capacity). The report statistically analyzes one year's worth of power variability data, applied to both the baseline and expansion scenarios, to evaluate diurnal and seasonal power fluctuations, different timescales of variability (e.g., from one to 15 minutes), the magnitude of variability (both total megawatts and relative to installed solar capacity), and the extent to which the variability can be anticipated in advance. The paper also examines how Gujarat Energy Transmission Corporation (GETCO) and the Gujarat State Load Dispatch Centre (SLDC) could make use of the solar variability profiles in grid operations and planning.

  15. LARGE-SCALE CORONAL PROPAGATING FRONTS IN SOLAR ERUPTIONS AS OBSERVED BY THE ATMOSPHERIC IMAGING ASSEMBLY ON BOARD THE SOLAR DYNAMICS OBSERVATORY—AN ENSEMBLE STUDY

    SciTech Connect

    Nitta, Nariaki V.; Schrijver, Carolus J.; Title, Alan M.; Liu, Wei

    2013-10-10

    This paper presents a study of a large sample of global disturbances in the solar corona with characteristic propagating fronts as intensity enhancement, similar to the phenomena that have often been referred to as Extreme Ultraviolet Imaging Telescope (EIT) waves or extreme-ultraviolet (EUV) waves. Now EUV images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory provide a significantly improved view of these large-scale coronal propagating fronts (LCPFs). Between 2010 April and 2013 January, a total of 171 LCPFs have been identified through visual inspection of AIA images in the 193 Å channel. Here we focus on the 138 LCPFs that are seen to propagate across the solar disk, first studying how they are associated with flares, coronal mass ejections (CMEs), and type II radio bursts. We measure the speed of the LCPF in various directions until it is clearly altered by active regions or coronal holes. The highest speed is extracted for each LCPF. It is often considerably higher than EIT waves. We do not find a pattern where faster LCPFs decelerate and slow LCPFs accelerate. Furthermore, the speeds are not strongly correlated with the flare intensity or CME magnitude, nor do they show an association with type II bursts. We do not find a good correlation either between the speeds of LCPFs and CMEs in a subset of 86 LCPFs observed by one or both of the Solar and Terrestrial Relations Observatory spacecraft as limb events.

  16. Comparing the extractable power and climatic impacts of very large-scale deployment of solar, wind, and biomass technologies

    NASA Astrophysics Data System (ADS)

    Miller, L. M.; Gans, F.; Pavlick, R.; Kleidon, A.

    2010-12-01

    The world is faced with two difficult problems: ever-increasing energy demands and climate change due primarily to the burning of fossil fuels. Overcoming these challenges will require the large-scale deployment of power technologies with low or zero greenhouse gas emissions. No power technology, however, will have zero climatic impact. Here, we compare the climatic impacts of the large-scale deployment of several such renewable power technologies (near-surface wind, photovoltaic solar, and second-generation biofuels) using an earth system model of intermediate complexity. All power technologies have an impact on the climate and alter the generation of power within the Earth system. For instance, we find that the maximum power that can be extracted from atmospheric motion is much less than previous estimates of the availability of wind power and this extraction reduces the ability of the atmosphere to generate motion, since the natural efficiency of the atmosphere to generate motion is already maximized. Solar power, in contrast, can convert incoming shortwave radiation into electric energy that would otherwise be "wasted" by the conversion into heat. Hence, solar power has the ability to enhance power generation within the Earth system, while large-scale extraction of wind power appears to weaken power generation. We provide estimates of the maximum realizable power potential for each resource along with its climate impacts in terms of standard metrics such as changes in 2-meter air temperature, surface heat flux partitioning, and precipitation. This understanding is then extended to include less-conventional metrics relating renewable power extraction to its impact on power generation in the Earth System (eg. atmospheric wind dissipation, terrestrial biosphere productivity, and the work done by the hydrologic cycle). Many previous assessments of large-scale renewable power technologies fail to consider the removal of power from the Earth System and its sometimes

  17. Contrasting Large Solar Events

    NASA Astrophysics Data System (ADS)

    Lanzerotti, Louis J.

    2010-10-01

    After an unusually long solar minimum, solar cycle 24 is slowly beginning. A large coronal mass ejection (CME) from sunspot 1092 occurred on 1 August 2010, with effects reaching Earth on 3 August and 4 August, nearly 38 years to the day after the huge solar event of 4 August 1972. The prior event, which those of us engaged in space research at the time remember well, recorded some of the highest intensities of solar particles and rapid changes of the geomagnetic field measured to date. What can we learn from the comparisons of these two events, other than their essentially coincident dates? One lesson I took away from reading press coverage and Web reports of the August 2010 event is that the scientific community and the press are much more aware than they were nearly 4 decades ago that solar events can wreak havoc on space-based technologies.

  18. Very Large-Scale Deployment of Grid-Connected Solar Photovoltaics in the United States: Challenges and Opportunities; Preprint

    SciTech Connect

    Denholm, P.; Margolis, R.

    2006-04-01

    This paper analyzes the potential for solar photovoltaics (PV) to be deployed on a very large scale and provide a large fraction of a system's electricity. It explicitly examines how the hourly availability of PV interacts with the limited flexibility of traditional electricity generation plants. The authors found that, under high penetration levels and existing grid-operation procedures and rules, the system will have excess PV generation during certain periods of the year. This excess PV generation results in increased costs, which can increase dramatically when PV provides on the order of 10%-15% of total electricity demand in systems that are heavily dependent on inflexible baseload steam plants. Measures to increase penetration of PV are also discussed, including increased system flexibility, increased dispatchable load, and energy storage.

  19. Link between local scale BC emissions in the Indo-Gangetic Plains and large scale atmospheric solar absorption

    NASA Astrophysics Data System (ADS)

    Praveen, P. S.; Ahmed, T.; Kar, A.; Rehman, I. H.; Ramanathan, V.

    2012-01-01

    Project Surya has documented indoor and outdoor concentrations of black carbon (BC) from traditional biomass burning cook stoves in a rural village located in the Indo-Gangetic Plains (IGP) region of N. India from November 2009-September 2010. In this paper, we systematically document the link between local scale aerosol properties and column averaged regional aerosol optical properties and atmospheric radiative forcing. We document observations from the first phase of Project Surya and estimate the source dependent (biomass and fossil fuels) aerosol optical properties from local to regional scale. Data were collected using surface based observations of BC, organic carbon (OC), aerosol light absorption, scattering coefficient at the Surya village (SVI_1) located in IGP region and integrated with satellite and AERONET observations at the regional scale (IGP). The daily mean BC concentrations at SVI1 showed a large increase of BC during the dry season (December to February) with values reaching 35 μg m-3. Space based LIDAR data revealed how the biomass smoke was trapped within the first kilometer during the dry season and extended to above 5 km during the pre-monsoon season. As a result, during the dry season, the variance in the daily mean single scattering albedo (SSA), the ratio of scattering to extinction coefficient, and column aerosol optical properties at the local IGP site correlated (with slopes in the range of 0.85 to 1.06 and R2>0.4) well with the "IGP_AERONET" (mean of six AERONET sites). The statistically significant correlation suggested that in-situ observations can be used to derive spatial mean forcing, at least for the dry season. The atmospheric forcing due to BC and OC exceeded 20 Wm-2 during all months from November to May, supporting the deduction that elimination of cook stove smoke emissions through clean cooking technologies will likely have a major positive impact not only on human health but also on regional climate.

  20. Dawn-dusk asymmetry in solar wind ion entry and dayside precipitation: Results from large-scale simulations

    NASA Astrophysics Data System (ADS)

    Berchem, J.; Richard, R.; Escoubet, P.; Wing, S.; Pitout, F.

    2014-03-01

    We present the results of numerical studies of the interaction of solar wind ions with the dayside magnetospheric boundary for a southward interplanetary magnetic field and two solar wind speeds (250 and 500 km/s) using the results of global magnetohydrodynamics simulations in conjunction with large-scale kinetic calculations. Results of these studies show that a dawn-dusk asymmetry is found in the precipitation of low- to middle-energy ions over the high-latitude dayside magnetosphere. This asymmetry is consistent with statistical studies of DMSP data showing that ion precipitation from the mantle is predominantly seen over the morning and prenoon sector. Analysis of energy-latitude spectra and study of individual particle trajectories from the simulations revealed that low-energy ions can enter the magnetopause at high latitudes in regions where the parallel electric field associated with the magnetopause current is positive and strong enough for the ions to gain energies of the order of the parallel potential drop across the magnetopause. Because the parallel electric field in the Northern Hemisphere is positive in the prenoon sector and negative in the afternoon-evening sector, solar wind ions reaching the magnetopause in these regions are accelerated toward the ionosphere on the dawnside and outward on the duskside, creating the asymmetry in precipitation. The same dawn-dusk asymmetry is found in the Southern Hemisphere because both parallel electric field and magnetic field are reversed in direction.

  1. The 40 KW of Solar Cell Modules for the Large Scale Production Task a Low Cost Silicon Solar Array Project

    NASA Technical Reports Server (NTRS)

    Jones, G. T.

    1977-01-01

    Forty kilowatts of solar cell modules was produced in this program. This is equivalent to 4123 modules. The average power output per module was 9.7 watts at 16.5 volts, 60 C and 100 mW/sq cm. The peak production rate was 200 modules per week which is equal to 1.9 kW per week. This rate was sustained for over four and one-half months and is equivalent to 100 kW per year. This final report covers the solar cell module design, electrical and power performance, module preproduction environmental test results, production and shipping schedule, program summary, and delivery. A cost analysis section is written. Particular emphasis on the percentage of labor and material utilized in constructing a solar cell module is presented. Also included are cost reduction recommendations.

  2. Large-scale travelling atmospheric disturbances in the night ionosphere during the solar terrestrial event of 23 May 2002

    NASA Astrophysics Data System (ADS)

    Lynn, K. J. W.; Gardiner-Garden, R.; Sjarifudin, M.; Terkildsen, M.; Shi, J.; Harris, T. J.

    2008-12-01

    This paper examines the night of 23 May 2002 as observed by a large number of Australian ionosondes (19) as well as others situated in New Guinea, Indonesia and China. The arrival of a solar Coronal Mass Ejection (CME) and subsequent negative Bz turnings in the solar wind resulted in a magnetic storm with two bursts of energy inputs into the auroral zones. The energy depositions produced two successive rise and falls in ionospheric height over a 300 km height range within the period 12.30-21.00 UT. The two events were seen in the night-side hemisphere by all ionosondes at Southeast Asian longitudes in the southern hemisphere, as well as in the northern hemisphere. In this paper, the simultaneity and spatial variability of these events is investigated. The first event, after an initial expansion towards the equator, ended with a retreat in the area of height rise back towards the auroral zone. The second event was of greater complexity and did not show such a steady variation in rise and fall times with latitude. Such events are often described as large-scale travelling atmospheric/ionospheric disturbances (LTADs or LTIDs). In the southern hemisphere, the front of the initial height rise was found to move at a speed up to 1300 m/s as was also measured by Tsugawa et al. [2006. Geomagnetic conjugate observations of large-scale travelling ionospheric disturbances using GPS networks in Japan and Australia. Journal of Geophysical Research 111, A02302] from small changes in GPS TEC. The front was uniform across the widest longitudinal range of observation (52° or 5360 km).The relationship between the subsequent fall in ionospheric height and an associated temporary increase in foF2 was found to be consistent with previous observations. Ionospheric drivers that move ionization up and down magnetic field lines are suggested as the common cause of the relationship between foF2 and height.

  3. Barriers to commercialization of large-scale solar electricity: Lessions learned from the LUZ experience

    SciTech Connect

    Lotker, M. , Westlake Village, CA )

    1991-11-01

    This report discusses the economic and policy factors leading to the initial successful introduction of Luz International Limited's Solar Electric Generating Systems (SEGS). It then addresses the wide range of barriers to continued SEGS commercialization, including state and federal tax policy, avoided cost energy pricing, artificial size limitations under the Public Utility Regulatory Policies Act (PURPA), the loss of effectiveness of PURPA itself, the lack of incentives available to utilities as owners of solar electric plants, and the limited ways in which the environmental benefits of this technology have been recognized. The way in which each of these barriers contributed to the suspension of new LUZ projects is highlighted. In addition, mitigation approaches to each of these barriers are suggested.

  4. Barriers to commercialization of large-scale solar electricity: Lessions learned from the LUZ experience

    SciTech Connect

    Lotker, M.

    1991-11-01

    This report discusses the economic and policy factors leading to the initial successful introduction of Luz International Limited`s Solar Electric Generating Systems (SEGS). It then addresses the wide range of barriers to continued SEGS commercialization, including state and federal tax policy, avoided cost energy pricing, artificial size limitations under the Public Utility Regulatory Policies Act (PURPA), the loss of effectiveness of PURPA itself, the lack of incentives available to utilities as owners of solar electric plants, and the limited ways in which the environmental benefits of this technology have been recognized. The way in which each of these barriers contributed to the suspension of new LUZ projects is highlighted. In addition, mitigation approaches to each of these barriers are suggested.

  5. Large-scale coronal structures in EUV and soft X-rays in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Benevolenskaya, E. E.; Kosovichev, A. G.; Scherrer, P. H.; Lemen, J. R.; Slater, G. L.

    2002-06-01

    We have analyzed the EIT/SOHO data in four EUV lines (171 Å, 195 Å, 284 Å and 304 Å) and soft X-ray YOHKOH data in two filters (AlMg and Al) in the form of coronal synoptic maps for the period 1996 - 2001 yrs. Two types of the bright structures have been detected in EUV in the axisymmetrically averaged synoptic maps. The structures of the first type migrate equatorward as the solar cycle progresses. They are related to complexes of sunspot activity and display the "butterfly"-type distribution. The structures of the second type migrate polarward and are associated with footpoints of giant coronal loops, which connect the polar regions and the following parts of the active complexes. These structures of coronal activity are also pronounced in the soft X-ray maps. However, the whole structure of the giant polar loops is visible in X-rays, and reveals connections to the low-latitude coronal structures. The relationship between the soft X-rays emission and the photospheric magnetic flux obtained from SOHO/MDI and Kitt Peak Solar Observatory has been investigated. It has been found that the relationship depends on the phase of the solar cycle. We discuss the role of the magnetic flux in the formation and evolution of the stable coronal structures during the rising phase of cycle 23.

  6. A large-scale view of Space Technology 5 magnetometer response to solar wind drivers

    NASA Astrophysics Data System (ADS)

    Knipp, D. J.; Kilcommons, L. M.; Gjerloev, J.; Redmon, R. J.; Slavin, J.; Le, G.

    2015-04-01

    In this data report we discuss reprocessing of the Space Technology 5 (ST5) magnetometer database for inclusion in NASA's Coordinated Data Analysis Web (CDAWeb) virtual observatory. The mission consisted of three spacecraft flying in elliptical orbits, from 27 March to 27 June 2006. Reprocessing includes (1) transforming the data into the Modified Apex Coordinate System for projection to a common reference altitude of 110km, (2) correcting gain jumps, and (3) validating the results. We display the averaged magnetic perturbations as a keogram, which allows direct comparison of the full-mission data with the solar wind values and geomagnetic indices.With the data referenced to a common altitude, we find the following: (1) Magnetic perturbations that track the passage of corotating interaction regions and high-speed solar wind; (2) unexpectedly strong dayside perturbations during a solstice magnetospheric sawtooth oscillation interval characterized by a radial interplanetary magnetic field (IMF) component that may have enhanced the accompanying modest southward IMF; and (3) intervals of reduced magnetic perturbations or "calms," associated with periods of slow solar wind, interspersed among variable-length episodic enhancements. These calms aremost evidentwhen the IMF is northward or projectswith a northward component onto the geomagnetic dipole. The reprocessed ST5 data are in very good agreement with magnetic perturbations from the Defense Meteorological Satellite Program (DMSP) spacecraft, which we also map to 110km. We briefly discuss the methods used to remap the ST5 data and the means of validating the results against DMSP. Our methods form the basis for future intermission comparisons of space-based magnetometer data.

  7. The solar wind structure that caused a large-scale disturbance of the plasma tail of comet Austin

    NASA Astrophysics Data System (ADS)

    Kozuka, Yukio; Konno, Ichishiro; Saito, Takao; Numazawa, Shigemi

    1992-12-01

    The plasma tail of Comet Austin (1989c1) showed remarkable disturbances because of the solar maximum periods and its orbit. Figure 1 shows photographs of Comet Austin taken in Shibata, Japan, on 29 Apr. 1990 UT, during about 20 minutes with the exposure times of 90 to 120 s. There are two main features in the disturbance; one is many bowed structures, which seem to move tailwards; and the other is a large-scale wavy structure. The bowed structures can be interpreted as arcade structures brushing the surface of both sides of the cometary plasma surrounding the nucleus. We identified thirteen structures of the arcades from each of the five photographs and calculated the relation between the distance of each structure from the cometary nucleus, chi, and the velocity, upsilon. The result is shown. This indicates that the velocity of the structures increases with distance. This is consistent with the result obtained from the observation at the Kiso Observatory.

  8. A facile chemical-mechanical polishing lift-off transfer process toward large scale Cu(In,Ga)Se2 thin-film solar cells on arbitrary substrates

    NASA Astrophysics Data System (ADS)

    Tseng, Kuan-Chun; Yen, Yu-Ting; Thomas, Stuart R.; Tsai, Hung-Wei; Hsu, Cheng-Hung; Tsai, Wen-Chi; Shen, Chang-Hong; Shieh, Jia-Min; Wang, Zhiming M.; Chueh, Yu-Lun

    2016-02-01

    The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm2 in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide variety of flexible substrates, suitable for use in the large scale CIGS photovoltaic industry.The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm2 in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide

  9. A Technique for Incorporating Large-scale Magnetic Fields Within Stellar Models: Implications for the Variability of the Solar Radius, Luminosity, and Pulsation Frequencies

    NASA Astrophysics Data System (ADS)

    Lydon, T. J.; Sofia, S.

    1994-12-01

    A set of physically consistent approximations are employed to include the effects of magnetic fields within the equations of stellar structure. A series of solar models are then constructed with large-scale (~0.1R_sun), intense (~10(6) gauss) magnetic fields. The results of such models are then compared to measurements of changes in the solar radius (from the Solar Disk Sextant Experiment) and changes in the solar p-mode frequencies in order to determine if such fields are associated with the solar cycle. This work was supported in part by an appointment to the Global Change Distinguished Postdoctoral Fellowships sponsored by the U.S. Department of Energy, Office of Health and Enviromental Research, and administered by the Oak Ridge Institute for Science and Education.

  10. Large scale dynamic systems

    NASA Technical Reports Server (NTRS)

    Doolin, B. F.

    1975-01-01

    Classes of large scale dynamic systems were discussed in the context of modern control theory. Specific examples discussed were in the technical fields of aeronautics, water resources and electric power.

  11. Large Scale Computing

    NASA Astrophysics Data System (ADS)

    Capiluppi, Paolo

    2005-04-01

    Large Scale Computing is acquiring an important role in the field of data analysis and treatment for many Sciences and also for some Social activities. The present paper discusses the characteristics of Computing when it becomes "Large Scale" and the current state of the art for some particular application needing such a large distributed resources and organization. High Energy Particle Physics (HEP) Experiments are discussed in this respect; in particular the Large Hadron Collider (LHC) Experiments are analyzed. The Computing Models of LHC Experiments represent the current prototype implementation of Large Scale Computing and describe the level of maturity of the possible deployment solutions. Some of the most recent results on the measurements of the performances and functionalities of the LHC Experiments' testing are discussed.

  12. Measurements of large-scale density fluctuations in the solar wind using dual-frequency phase scintillations

    NASA Technical Reports Server (NTRS)

    Woo, R.; Yang, F.-C.; Yip, K. W.; Kendall, W. B.

    1976-01-01

    It is demonstrated that phase-difference scintillations measured with a coherent dual-frequency radio system such as that on Mariner 10 can be used to study the structure of density fluctuations in the solar wind covering a wider range of scale sizes than has ever been possible before. The Mariner 10 observations at solar elongations of 11.5 and 12.6 deg show that the density spectrum in the frequency range from 0.0001 to 0.5 Hz, which corresponds to the spatial wavenumber range of 2 millionths to 0.001 inverse km if the solar wind velocity is assumed to be 350 km/s, is approximately power-law and close to Kolmogorov (spectral index of 11/3). The results are consistent with direct spacecraft observations near earth and provide strong evidence that the density fluctuations are produced by turbulence. The potential and benefits of future extensive measurements are also discussed.

  13. On the variation of the ionospheric potential due to large-scale radioactivity enhancement and solar activity

    NASA Astrophysics Data System (ADS)

    Slyunyaev, Nikolay N.; Mareev, Evgeny A.; Zhidkov, Artem A.

    2015-08-01

    Sensitivity of the global electric circuit (GEC) to variations of atmospheric conductivity and current sources is analyzed and discussed. When the undisturbed exponential conductivity profile is assumed all over the Earth, the most substantial changes in the ionospheric potential (IP) are caused by conductivity perturbations inside thunderstorms; if, in addition, conductivity reduction inside thunderstorms and nonelectrified clouds is assumed, the IP becomes less sensitive to conductivity perturbations; besides, the IP is even more sensitive to source current variations than to conductivity. Current source and voltage source descriptions of GEC generators are compared; it is shown that the IP variation may critically depend on the chosen description. As an application, the IP variation due to nuclear weapons testing is studied; it is shown that neither local nor global increase of conductivity in the stratosphere could alone explain the observed 40% IP increase in the 1960s; at the same time this increase might be accounted for by a 40% increase in the source current density or a 46% reduction of the conductivity inside thunderstorms, provided that it was not reduced initially. The IP variation due to solar activity and, in particular, due to solar modulation of galactic cosmic ray flux is also discussed and modeled, which required an adequate parameterization of the rate of atmospheric ion pair production over the solar cycle. It is estimated that the maximum IP variation on the scale of the solar cycle does not exceed 5% of the mean value, unless source current perturbations are taken into account.

  14. A facile chemical-mechanical polishing lift-off transfer process toward large scale Cu(In,Ga)Se2 thin-film solar cells on arbitrary substrates.

    PubMed

    Tseng, Kuan-Chun; Yen, Yu-Ting; Thomas, Stuart R; Tsai, Hung-Wei; Hsu, Cheng-Hung; Tsai, Wen-Chi; Shen, Chang-Hong; Shieh, Jia-Min; Wang, Zhiming M; Chueh, Yu-Lun

    2016-03-01

    The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm(2) in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide variety of flexible substrates, suitable for use in the large scale CIGS photovoltaic industry. PMID:26878109

  15. Effect of large-scale disturbances of the solar wind on the dynamics of relativistic electrons of the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Bezrodnykh, I. P.; Morozova, E. I.; Shafer, Iu. G.

    1987-01-01

    The relationship betwen intensity increases of electrons in the outer magnetosphere and large-scale disturbances of the solar wind is investigated on the basis of Prognoz-6,7 and Raduga satellite measurements of high-energy (1 MeV) electrons. It is shown that the effect of high-speed solar-wind streams on the magnetosphere consists in the acceleration of electrons near the magnetopause and in the intensification of the transfer of the accelerated particles (as well as those exsisting in the interplanetary medium) into the magnetosphere. Particular attention is given to Dst variations and the dynamics of relativistic electrons at L = 6.6.

  16. Effect of large-scale disturbances of the solar wind on the dynamics of relativistic electrons of the outer radiation belt

    SciTech Connect

    Bezrodnykh, I.P.; Morozova, E.I.; Shafer, Yu.F.

    1987-07-01

    The relationship of increases in the intensities of electrons in the outer magnetosphere and large-scale disturbances of the solar wind is studied with measurements of fluxes of energetic (E/sub e/ approx. 1 MeV) electrons made on the satellites Prognoz-6, -7, and Raduga. It is shown that the effect of high-speed solar wind fluxes on the geomagnetosphere involves the acceleration of electrons near the magnetopause and the enhancement of charged-particle transport into the magnetosphere from the boundary.

  17. Large-Scale Disasters

    NASA Astrophysics Data System (ADS)

    Gad-El-Hak, Mohamed

    "Extreme" events - including climatic events, such as hurricanes, tornadoes, and drought - can cause massive disruption to society, including large death tolls and property damage in the billions of dollars. Events in recent years have shown the importance of being prepared and that countries need to work together to help alleviate the resulting pain and suffering. This volume presents a review of the broad research field of large-scale disasters. It establishes a common framework for predicting, controlling and managing both manmade and natural disasters. There is a particular focus on events caused by weather and climate change. Other topics include air pollution, tsunamis, disaster modeling, the use of remote sensing and the logistics of disaster management. It will appeal to scientists, engineers, first responders and health-care professionals, in addition to graduate students and researchers who have an interest in the prediction, prevention or mitigation of large-scale disasters.

  18. Spatial distribution of large-scale solar magnetic fields and their relation to the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Levine, R. H.

    1979-01-01

    The spatial organization of the observed photospheric magnetic field as well as its relation to the polarity of the IMF have been studied using high resolution magnetograms from the Kitt Peak National Observatory. Systematic patterns in the large scale field are due to contributions from both concentrated flux and more diffuse flux. The polarity of the photospheric field, determined on various spatial scales, correlates with the polarity of the IMF. Analyses based on several spatial scales in the photosphere suggest that new flux in the interplanetary medium is often due to relatively small photospheric features which appear in the photosphere up to one month before they are manifest at the earth.

  19. Variations over time in latitudinal distribution of the large-scale magnetic fields in the solar atmosphere at heights from the photosphere to the source surface

    NASA Astrophysics Data System (ADS)

    Akhtemov, Z. S.; Andreyeva, O. A.; Rudenko, G. V.; Stepanian, N. N.; Fainshtein, V. G.

    2015-02-01

    Calculations of magnetic field in the solar atmosphere and the "potential field-source surface" model have been used to study time variations in several parameters of the large-scale magnetic field at various heights during the last four solar cycles. At ten heights from the solar surface (R = Ro) to the source surface (R = 2.5Ro), we have constructed synoptic charts (SC) of the radial component Br of the estimated magnetic field. For these SC, we have identified 10-degree latitudinal zones. Within these zones, we found values of Sp (positive Br values averaged within the latitudinal zone over latitude and longitude), Sm (averaged modulus of negative Br values) and S + fields (a part of the latitudinal zone area (in %) occupied by positive Br values). At lower latitudes, cyclic variations in the Sp + Sm parameter are demonstrated to be similar (but not in detail) to time variations in Wolf numbers. Latitudes of 55° and higher exhibited virtually no cyclic peculiarities of time variations in this parameter. The authors believe that this indicates the diverse nature of the large-scale magnetic field in the near-equatorial and polar regions of the solar atmosphere. At R = 2.5Ro, Sp + Sm cyclic variations are almost invisible at all latitudes and only slightly apparent near the equator. The analysis of S + fields variations revealed that at low latitudes at R = 2.5Ro during solar cycles 21, 22 and ascending phase of cycle 23 there were almost no mixed-polarity periods. However, beginning from the maximum of cycle 23, in the near-equatorial region the mixed polarity was observed until the end of the long solar activity minimum. An assumption has been made that this might have been one of the forerunners and manifestations of the prolonged minimum between cycles 23 and 24. It has been found that during solar activity minima poleward there appears motion of magnetic fields with polarity opposite to that of the field at the pole. We have estimated the velocity of such a

  20. Nitrogen isotopes in the recent solar wind from the analysis of genesis targets: evidence for large scale isotope heterogeneity in the nascent solar system

    SciTech Connect

    Wiens, Roger C; Marty, Bernard; Zimmermann, Laurent; Burnard, Peter G; Burnett, Donald L; Heber, Veronika S; Wieler, Rainer; Bochsler, Peter

    2009-01-01

    Nitrogen, the fifth most abundant element in the universe, displays the largest stable isotope variations in the solar system reservoirs after hydrogen. Yet the value of isotopic composition of solar nitrogen, presumably the best proxy of the protosolar nebula composition, is not known. Nitrogen isotopes trapped in Genesis spacecraft target material indicate a 40 % depletion of {sup 15}N in solar wind N relative to inner planets and meteorites, and define a composition for the present-day Sun undistinguishable from that of Jupiter's atmosphere. These results indicate that the isotopic composition of of nitrogen in the outer convective zone of the Sun (OCZ) has not changed through time, and is representative of the protosolar nebula. Large {sup 15}N enrichments during e.g., irradiation, or contributions from {sup 15}N-rich presolar components, are required to account for planetary values.

  1. An Assessment of Water Demand and Availability to meet Construction and Operational Needs for Large Utility-Scale Solar Projects in the Southwestern United States

    NASA Astrophysics Data System (ADS)

    Klise, G. T.; Tidwell, V. C.; Macknick, J.; Reno, M. D.; Moreland, B. D.; Zemlick, K. M.

    2013-12-01

    In the Southwestern United States, there are many large utility-scale solar photovoltaic (PV) and concentrating solar power (CSP) facilities currently in operation, with even more under construction and planned for future development. These are locations with high solar insolation and access to large metropolitan areas and existing grid infrastructure. The Bureau of Land Management, under a reasonably foreseeable development scenario, projects a total of almost 32 GW of installed utility-scale solar project capacity in the Southwest by 2030. To determine the potential impacts to water resources and the potential limitations water resources may have on development, we utilized methods outlined by the Bureau of Land Management (BLM) to determine potential water use in designated solar energy zones (SEZs) for construction and operations & maintenance (O&M), which is then evaluated according to water availability in six Southwestern states. Our results indicate that PV facilities overall use less water, however water for construction is high compared to lifetime operational water needs. There is a transition underway from wet cooled to dry cooled CSP facilities and larger PV facilities due to water use concerns, though some water is still necessary for construction, operations, and maintenance. Overall, ten watersheds, 9 in California, and one in New Mexico were identified as being of particular concern because of limited water availability. Understanding the location of potentially available water sources can help the solar industry determine locations that minimize impacts to existing water resources, and help understand potential costs when utilizing non-potable water sources or purchasing existing appropriated water. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract

  2. Evolution of Large-scale Solar Magnetic Fields in a Flux-Transport Model Including a Multi-cell Meridional Flow

    NASA Astrophysics Data System (ADS)

    McDonald, E.; Dikpati, M.

    2003-12-01

    Advances in helioseismology over the past decade have enabled us to detect subsurface meridional flows in the Sun. Some recent helioseismological analysis (Giles 1999, Haber et al. 2002) has indicated a submerged, reverse flow cell occurring at high latitudes of the Sun's northern hemisphere between 1998 and 2001. Meridional circulation plays an important role in the operation of a class of large-scale solar dynamo, the so-called "flux-transport" dynamo. In such dynamo models, the poleward drift of the large-scale solar magnetic fields and the polar reversal process are explained by the advective-diffusive transport of magnetic flux by a meridional circulation with a poleward surface flow component. Any temporal and spatial variations in the meridional flow pattern are expected to greatly influence the evolution of large-scale magnetic fields in a flux-transport dynamo. The aim of this paper is to explore the implications of a steady, multi-cell flow on the advection of weak, large-scale, magnetic flux. We present a simple, two-cell flux transport model operating in an r-theta cross-section of the northern hemisphere. Azimuthal symmetry is assumed. Performing numerical flux-transport simulations with a reverse flow cell at various latitudes, we demonstrate the effect of this cell on the evolutionary pattern of the large-scale diffuse fields. We also show how a flux concentration may occur at the latitude where the radial flows of the two cells are sinking downward. This work is supported by NASA grants W-19752, W-10107, and W-10175. The National Center for Atmospheric Research is sponsored by the National Science Foundation.

  3. Solar system to scale

    NASA Astrophysics Data System (ADS)

    Gerwig López, Susanne

    2016-04-01

    One of the most important successes in astronomical observations has been to determine the limit of the Solar System. It is said that the first man able to measure the distance Earth-Sun with only a very slight mistake, in the second century BC, was the wise Greek man Aristarco de Samos. Thanks to Newtońs law of universal gravitation, it was possible to measure, with a little margin of error, the distances between the Sun and the planets. Twelve-year old students are very interested in everything related to the universe. However, it seems too difficult to imagine and understand the real distances among the different celestial bodies. To learn the differences among the inner and outer planets and how far away the outer ones are, I have considered to make my pupils work on the sizes and the distances in our solar system constructing it to scale. The purpose is to reproduce our solar system to scale on a cardboard. The procedure is very easy and simple. Students of first year of ESO (12 year-old) receive the instructions in a sheet of paper (things they need: a black cardboard, a pair of scissors, colored pencils, a ruler, adhesive tape, glue, the photocopies of the planets and satellites, the measurements they have to use). In another photocopy they get the pictures of the edge of the sun, the planets, dwarf planets and some satellites, which they have to color, cut and stick on the cardboard. This activity is planned for both Spanish and bilingual learning students as a science project. Depending on the group, they will receive these instructions in Spanish or in English. When the time is over, the students bring their works on their cardboard to the class. They obtain a final mark: passing, good or excellent, depending on the accuracy of the measurements, the position of all the celestial bodies, the asteroids belts, personal contributions, etc. If any of the students has not followed the instructions they get the chance to remake it again properly, in order not

  4. The dynamics of large-scale meridional flows in the solar interior, and their role in establishing the observed rotational balance

    NASA Astrophysics Data System (ADS)

    Garaud, P.

    2009-12-01

    The rotation profile of the solar interior, as observed by helioseismology, exhibits a sharp transition at the base of the convection zone. Above the radiative-convective interface, strong differential rotation is observed while the radiative zone itself is in near-uniform rotation. To date, the only self-consistent published model of the dynamics of the transition region, the solar tachocline, is the one proposed by Gough & McIntyre (1998). In this model, large-scale meridional flows are "gyroscopically pumped" by the differential rotation in the convection zone, down-well into the radiative zone where they encounter a large-scale primordial magnetic field. The magnetic field is thereby confined by the down-welling flows within the radiative zone only, and imposes the observed differential rotation. In this talk, I review a series of new results inspired by this original idea, each of which provides insight into a different aspect of the problem. The new picture which emerges from these related explorations clarifies many outstanding issues, and provides guidance for future investigations. These results begin with a study of the angular-momentum balance of the radiative interior (Garaud & Guervilly 2009), assuming the presence of a confined magnetic field and neglecting the role of meridional flows (a model which is identical to the one originally proposed by Ruediger & Kitchatinov, 1997). We show analytically that this model systematically fails to explain the observed value of the rotation rate of the radiative zone. This implies that, within the Gough & McIntyre model framework, the dynamics of the convection zone flows in the tachocline are crucial not only for field confinement but also for angular-momentum transport. We then present an exhaustive study of a toy model for gyroscopic pumping of large-scale meridional flows by the solar convection zone (Garaud & Acevedo-Arreguin 2009), which 1. illustrates the phenomenon pedagogically 2. quantifies the

  5. Dynamics of the large-scale open solar magnetic field and its specific features in the zone of the main active longitudes in 2006-2012

    NASA Astrophysics Data System (ADS)

    Ivanov, K. G.; Kharshiladze, A. F.

    2013-11-01

    The dynamics of the absolute global values (Φ) of the large-scale open solar magnetic field (LOSMF) fluxes at an interval of one solar rotation in 2006-2012 has been studied based on the Wilcox Solar Observatory data and using the ISOPAK original package for modeling the solar magnetic field. The reference points and the duration of the final quasi-biennial interval in cycle 23 (January 2006-May 2007; 17 months) and the phases of the cycle 24 minimum (May 2007-November 2009; 30 months), growth (November 2009-May 2012; 30 months), and the beginning of the maximum (May 2012-January 2013) have been determined. It has been indicated that the absolute values (Φ) decreased sharply at the beginning of the minimum, growth, and the maximum phases to ˜(2, 1.25, 0.75) × 1022 Mx, respectively. During the entire minimum phase, LOSMF corotated super-quasi-rigidly westward in the direction of solar rotation; at the beginning of the growth phase, this field started corotating mostly eastward. The LOSMF polarity reversal in the current cycle 24 started in May-June 2012 (CR 2123-2124), when fields of southern polarity rushed from the Sun's southern hemisphere toward the north. The statement that the solar cycle is a continuous series of quasi-biennial LOSMF intervals is confirmed. In particular, the minimum and growth phases are characterized by opposite LOSMF rotation directions, i.e., super-quasi-rigid corotation (twisting) and detwisting, with identical duration at least in cycle 24.

  6. Large scale tracking algorithms.

    SciTech Connect

    Hansen, Ross L.; Love, Joshua Alan; Melgaard, David Kennett; Karelitz, David B.; Pitts, Todd Alan; Zollweg, Joshua David; Anderson, Dylan Z.; Nandy, Prabal; Whitlow, Gary L.; Bender, Daniel A.; Byrne, Raymond Harry

    2015-01-01

    Low signal-to-noise data processing algorithms for improved detection, tracking, discrimination and situational threat assessment are a key research challenge. As sensor technologies progress, the number of pixels will increase signi cantly. This will result in increased resolution, which could improve object discrimination, but unfortunately, will also result in a significant increase in the number of potential targets to track. Many tracking techniques, like multi-hypothesis trackers, suffer from a combinatorial explosion as the number of potential targets increase. As the resolution increases, the phenomenology applied towards detection algorithms also changes. For low resolution sensors, "blob" tracking is the norm. For higher resolution data, additional information may be employed in the detection and classfication steps. The most challenging scenarios are those where the targets cannot be fully resolved, yet must be tracked and distinguished for neighboring closely spaced objects. Tracking vehicles in an urban environment is an example of such a challenging scenario. This report evaluates several potential tracking algorithms for large-scale tracking in an urban environment.

  7. Large scale traffic simulations

    SciTech Connect

    Nagel, K.; Barrett, C.L.; Rickert, M.

    1997-04-01

    Large scale microscopic (i.e. vehicle-based) traffic simulations pose high demands on computational speed in at least two application areas: (i) real-time traffic forecasting, and (ii) long-term planning applications (where repeated {open_quotes}looping{close_quotes} between the microsimulation and the simulated planning of individual person`s behavior is necessary). As a rough number, a real-time simulation of an area such as Los Angeles (ca. 1 million travellers) will need a computational speed of much higher than 1 million {open_quotes}particle{close_quotes} (= vehicle) updates per second. This paper reviews how this problem is approached in different projects and how these approaches are dependent both on the specific questions and on the prospective user community. The approaches reach from highly parallel and vectorizable, single-bit implementations on parallel supercomputers for Statistical Physics questions, via more realistic implementations on coupled workstations, to more complicated driving dynamics implemented again on parallel supercomputers. 45 refs., 9 figs., 1 tab.

  8. Storm-time response of the Van Allen radiation belts organized by the large-scale solar wind drivers, energy and distance

    NASA Astrophysics Data System (ADS)

    Hietala, Heli; Kilpua, Emilia; Turner, Drew

    2016-04-01

    We study the response of the Van Allen radiation belts during geomagnetic storms. A combination of the long-term geosynchronous observations from GOES (> 2.5 MeV) and energy (tens of keV to 2 MeV) and L-shell (2.5 < L < 6.0) resolved Van Allen Probe observations are used. We demonstrate that the radiation belt response (depletion, no-change, increase) is organized by the large-scale solar wind driver (coronal mass ejection ejecta/sheath, slow-fast stream interface region, fast stream) and that the response is highly dependent on both the electron energy and the L-shell. In addition, we show detailed Van Allen Probe observations from two geomagnetic storms that occurred during two consecutive Carrington rotations of the solar maximum year 2015. Both of these storms involved a slow-fast stream interaction region and a fast stream originating from the same coronal hole. However, the first storm also included a large-scale coronal mass ejection. We study in particular how the added presence of this coronal mass ejection affected the dynamics of the radiation belts.

  9. Large area pulsed solar simulator

    NASA Technical Reports Server (NTRS)

    Kruer, Mark A. (Inventor)

    1999-01-01

    An advanced solar simulator illuminates the surface a very large solar array, such as one twenty feet by twenty feet in area, from a distance of about twenty-six feet with an essentially uniform intensity field of pulsed light of an intensity of one AMO, enabling the solar array to be efficiently tested with light that emulates the sun. Light modifiers sculpt a portion of the light generated by an electrically powered high power Xenon lamp and together with direct light from the lamp provide uniform intensity illumination throughout the solar array, compensating for the square law and cosine law reduction in direct light intensity, particularly at the corner locations of the array. At any location within the array the sum of the direct light and reflected light is essentially constant.

  10. Prompt arrival of solar energetic particles from far eastern events: The role of large-scale interplanetary magnetic field structure

    SciTech Connect

    Richardson, I.G.; Cane, H.V.; von Rosenvinge, T.T. )

    1991-05-01

    Intensity-time profiles of solar energetic particle enhancements generally show an asymmetry with respect to the heliolongitude of the associated solar event. Particles arrive promptly form events to the west of an observer because of good magnetic connection whereas particle enhancements from poorly connected eastern source regions usually show much slower onsets. However, some 15% of eastern events do show prompt onsets. Two prompt particle enhancements associated with eastern solar events are studied using data from the Goddard Space Flight Center instruments on the ISEE 3 and IMP 8 spacecraft. In both events the prompt particle onset was observed when the spacecraft were in a postshock plasma region, apparently within a magnetic bottle. They suggest that the magnetic bottle extended back to the Sun and served as a channel for fast particle propagation to the spacecraft. Particles accelerated at an expanding coronal shock initiated by the eastern event could be injected onto field lines in the foot of the bottle.

  11. Prompt arrival of solar energetic particles from far eastern events - The role of large-scale interplanetary magnetic field structure

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.; Von Rosenvinge, T. T.

    1991-01-01

    Intensity-time profiles of solar energetic particle enhancements generally show an asymmetry with respect to the heliolongitude of the associated solar event. Particles arrive promptly from events to the west of an observer because of good magnetic connection, whereas particle enhancements from poorly connected eastern source regions usually show much slower onsets. However, some 15 percent of eastern events do show prompt onsets. Two prompt particle enhancements associated with eastern solar events are studied using data from the Goddard Space Flight Center instruments on the ISEE 3 and IMP 8 spacecraft. In both events the prompt particle onset was observed when the spacecraft were in a postshock plasma region, apparently within a magnetic bottle. It is suggested that the magnetic bottle extended back to the sun and served as a channel for fast particle propagation to the spacecraft. Particles accelerated at an expanding coronal shock initiated by the eastern event could be injected onto field lines in the foot of the bottle.

  12. NONLINEAR FORCE-FREE FIELD EXTRAPOLATION OF A CORONAL MAGNETIC FLUX ROPE SUPPORTING A LARGE-SCALE SOLAR FILAMENT FROM A PHOTOSPHERIC VECTOR MAGNETOGRAM

    SciTech Connect

    Jiang, Chaowei; Wu, S. T.; Hu, Qiang; Feng, Xueshang E-mail: wus@uah.edu E-mail: fengx@spaceweather.ac.cn

    2014-05-10

    Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength ≲ 100 G), where the PIL is very fragmented due to small parasitic polarities on both sides of the PIL and the transverse field has a low signal-to-noise ratio. Thus, extrapolating a large-scale FR in such a case represents a far more difficult challenge. We demonstrate that our CESE-MHD-NLFFF code is sufficient for the challenge. The numerically reproduced magnetic dips of the extrapolated FR match observations of the filament and its barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.

  13. Nonlinear Force-free Field Extrapolation of a Coronal Magnetic Flux Rope Supporting a Large-scale Solar Filament from a Photospheric Vector Magnetogram

    NASA Astrophysics Data System (ADS)

    Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang

    2014-05-01

    Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength <~ 100 G), where the PIL is very fragmented due to small parasitic polarities on both sides of the PIL and the transverse field has a low signal-to-noise ratio. Thus, extrapolating a large-scale FR in such a case represents a far more difficult challenge. We demonstrate that our CESE-MHD-NLFFF code is sufficient for the challenge. The numerically reproduced magnetic dips of the extrapolated FR match observations of the filament and its barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.

  14. Large-scale variations of thermal electron parameters in the solar wind between 0.3 and 1 AU

    NASA Astrophysics Data System (ADS)

    1990-05-01

    Variations of thermal electron parameters in the solar wind are investigated using data obtained from the Helios probes in the years from 1974 to 1976, shortly before solar minimum, at heliocentric distances ranging from 0.3 to 1 AU. The main part of the present analysis is based on Helios 2 data obtained in 1976. Variations across the sector structure of the interplanetary magnetic field (IMF) and across the plasma stream structures are studied. These studies support the hypothesis that the thermal electron properties, i.e., the electron temperatures, the core temperatures, the heat flux, and the normalized heat flux, are strongly correlated with the distance from the neutral sheet in the IMF (implying also a correlation with the plasma stream structures). The results do not indicate significant electron heating in compression regions. Also, power laws for the variations of the electron parameters with distance from the Sun as well as polytrope laws are derived for different solar wind structures and distance ranges. The core temperatures, determined by bi-Maxwellian fits to the electron distributions below 20 or 30 eV, mostly decrease faster with distance from the Sun than the electron temperatures Te∥ and Te⊥, parallel and perpendicular to the magnetic field, respectively, as determined from the entire electron distributions. Most of the Helios 2 observations indicate that the radial profiles of electron temperatures and of electron heat flux tend to be flatter in high-speed streams embedded within the interior of magnetic sectors than in the slow- and intermediate-speed solar wind and in compression regions mostly at or near sector boundaries. For high-speed streams, the Helios data indicate a flattening of the radial profiles for Te⊥ with increasing distance from the Sun. For Te∥ this effect is not as evident in the case of Helios 2 data but is indicated by Helios 1 data. Analogous trends are observed for most of the derived polytrope indices for the

  15. Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface

    SciTech Connect

    Jiang, J.; Cameron, R. H.; Schüssler, M.

    2014-08-10

    The tilt angles of sunspot groups represent the poloidal field source in Babcock-Leighton-type models of the solar dynamo and are crucial for the build-up and reversals of the polar fields in surface flux transport (SFT) simulations. The evolution of the polar field is a consequence of Hale's polarity rules, together with the tilt angle distribution which has a systematic component (Joy's law) and a random component (tilt-angle scatter). We determine the scatter using the observed tilt angle data and study the effects of this scatter on the evolution of the solar surface field using SFT simulations with flux input based upon the recorded sunspot groups. The tilt angle scatter is described in our simulations by a random component according to the observed distributions for different ranges of sunspot group size (total umbral area). By performing simulations with a number of different realizations of the scatter we study the effect of the tilt angle scatter on the global magnetic field, especially on the evolution of the axial dipole moment. The average axial dipole moment at the end of cycle 17 (a medium-amplitude cycle) from our simulations was 2.73 G. The tilt angle scatter leads to an uncertainty of 0.78 G (standard deviation). We also considered cycle 14 (a weak cycle) and cycle 19 (a strong cycle) and show that the standard deviation of the axial dipole moment is similar for all three cycles. The uncertainty mainly results from the big sunspot groups which emerge near the equator. In the framework of Babcock-Leighton dynamo models, the tilt angle scatter therefore constitutes a significant random factor in the cycle-to-cycle amplitude variability, which strongly limits the predictability of solar activity.

  16. Effects of the Scatter in Sunspot Group Tilt Angles on the Large-scale Magnetic Field at the Solar Surface

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Cameron, R. H.; Schüssler, M.

    2014-08-01

    The tilt angles of sunspot groups represent the poloidal field source in Babcock-Leighton-type models of the solar dynamo and are crucial for the build-up and reversals of the polar fields in surface flux transport (SFT) simulations. The evolution of the polar field is a consequence of Hale's polarity rules, together with the tilt angle distribution which has a systematic component (Joy's law) and a random component (tilt-angle scatter). We determine the scatter using the observed tilt angle data and study the effects of this scatter on the evolution of the solar surface field using SFT simulations with flux input based upon the recorded sunspot groups. The tilt angle scatter is described in our simulations by a random component according to the observed distributions for different ranges of sunspot group size (total umbral area). By performing simulations with a number of different realizations of the scatter we study the effect of the tilt angle scatter on the global magnetic field, especially on the evolution of the axial dipole moment. The average axial dipole moment at the end of cycle 17 (a medium-amplitude cycle) from our simulations was 2.73 G. The tilt angle scatter leads to an uncertainty of 0.78 G (standard deviation). We also considered cycle 14 (a weak cycle) and cycle 19 (a strong cycle) and show that the standard deviation of the axial dipole moment is similar for all three cycles. The uncertainty mainly results from the big sunspot groups which emerge near the equator. In the framework of Babcock-Leighton dynamo models, the tilt angle scatter therefore constitutes a significant random factor in the cycle-to-cycle amplitude variability, which strongly limits the predictability of solar activity.

  17. Quenching of the beam-plasma instability by large-scale density fluctuations in 3 dimensions. [Langmuir waves in type 3 solar radio bursts

    NASA Technical Reports Server (NTRS)

    Muschietti, L.; Goldman, M. V.; Newman, D.

    1985-01-01

    The highly variable, yet low, level of Langmuir waves measured in situ by spacecraft when electron beams associated with type III solar bursts are passing by are addressed by a model based on the existence of large scale density fluctuations capable of sufficiently diffusing small-k beam-unstable Langmuir waves in phase space. The model is also informed by the presence of a significant isotropic nonthermal tail in the distribution function of the background electron population, which is capable of stabilizing larger k modes. The model is able to predict various levels of Langmuir waves, depending on the parameters; calculations indicate that, for realistic parameters, the most unstable small k modes are fully stabilized, while some oblique mode with higher k and lower growth rate may remain unstable.

  18. Very Large Scale Optimization

    NASA Technical Reports Server (NTRS)

    Vanderplaats, Garrett; Townsend, James C. (Technical Monitor)

    2002-01-01

    The purpose of this research under the NASA Small Business Innovative Research program was to develop algorithms and associated software to solve very large nonlinear, constrained optimization tasks. Key issues included efficiency, reliability, memory, and gradient calculation requirements. This report describes the general optimization problem, ten candidate methods, and detailed evaluations of four candidates. The algorithm chosen for final development is a modern recreation of a 1960s external penalty function method that uses very limited computer memory and computational time. Although of lower efficiency, the new method can solve problems orders of magnitude larger than current methods. The resulting BIGDOT software has been demonstrated on problems with 50,000 variables and about 50,000 active constraints. For unconstrained optimization, it has solved a problem in excess of 135,000 variables. The method includes a technique for solving discrete variable problems that finds a "good" design, although a theoretical optimum cannot be guaranteed. It is very scalable in that the number of function and gradient evaluations does not change significantly with increased problem size. Test cases are provided to demonstrate the efficiency and reliability of the methods and software.

  19. PROBA2/SWAP EUV images of the large-scale EUV corona up to 3 solar radii: Can we close the gap in coronal magnetic field structure between 1.3 and 2.5 solar radii?

    NASA Astrophysics Data System (ADS)

    De Groof, Anik; Seaton, Daniel B.; Rachmeler, Laurel; Berghmans, David

    2015-04-01

    The EUV telescope PROBA2/SWAP has been observing the solar corona in a bandpass near 17.4 nm since February 2010. SWAP's wide field-of-view provides a unique and continuous view of the extended EUV corona up to 2-3 solar radii. By carefully processing and combining multiple SWAP images, low-noise composites were produced that reveal large-scale, EUV-emitting, coronal structures. These extended structures appear mainly above or at the edges of active regions and typically curve towards the poles. As they persist for multiple Carrington rotations and cannot easily be related to white-light features, they give an interesting view on how the coronal magnetic field is structured between 1.3 and 2-3 solar radii, in the gap between SDO/AIA’s FOV and typical lower boundaries of coronagraph FOVs. With the help of magnetic field models, we analyse the geometry of the extended EUV structures in more detail and compare with sporadic EUV coronagraph measurements up to as close as 1.5Rs. The opportunities that Solar Orbiter’s future observations will bring are explored.

  20. Large Solar-Rejection Filter

    NASA Technical Reports Server (NTRS)

    Roberts, William; Sheikh, David; Patrick, Brian

    2007-01-01

    NASA utilized Image Intensified Video Cameras for ATV data acquisition from a jet flying at 12.8 km. Afterwards the video was digitized and then analyzed with a modified commercial software package, Image Systems Trackeye. Astrometric results were limited by saturation, plate scale, and imposed linear plate solution based on field reference stars. Time-dependent fragment angular trajectories, velocities, accelerations, and luminosities were derived in each video segment. It was evident that individual fragments behave differently. Photometric accuracy was insufficient to confidently assess correlations between luminosity and fragment spatial behavior (velocity, deceleration). Use of high resolution digital video cameras in future should remedy this shortcoming. A scenically accurate description of matter interpreted as a substance made up of corpuscular constituents was established during the course of the 19th century. In this description, atoms--the building blocks of the matter--form molecules. The properties of the molecules were described by chemistry or thermodynamics depending on what characteristics of the matter were investigated. In both theories, the molecules can dissociate to atoms when the kinetic energies of the atoms exceed the strength of the chemical bonds. The number of atoms is always preserved in a closed system. This is not true, however, when the matter takes up much higher energies at relativistic scales. New particles can be produced at the expense of the kinetic energy. The number of particles is no longer preserved. There are other conserved quantities, however, these quantities, the charge, baryon number, lepton number, are associated with particles that are considered elementary today. The properties and behavior of these elementary particles is the subject of Particle Physics or High Energy Physics. Practice Page: A crewmember touching a positively charged surface was thought to be galvanically isolated from the vehicle ground

  1. India's National Large Solar Telescope

    NASA Astrophysics Data System (ADS)

    Hasan, S. S.

    2012-12-01

    India's 2-m National Large Solar Telescope (NLST) is aimed primarily at carrying out observations of the solar atmosphere with high spatial and spectral resolution. A comprehensive site characterization program, that commenced in 2007, has identified two superb sites in the Himalayan region at altitudes greater than 4000-m that have extremely low water vapor content and are unaffected by monsoons. With an innovative optical design, the NLST is an on-axis Gregorian telescope with a low number of optical elements to reduce the number of reflections and yield a high throughput with low polarization. In addition, it is equipped with a high-order adaptive optics to produce close to diffraction limited performance. To control atmospheric and thermal perturbations of the observations, the telescope will function with a fully open dome, to achieve its full potential atop a 25 m tower. Given its design, NLST can also operate at night, without compromising its solar performance. The post-focus instruments include broad-band and tunable Fabry-Pérot narrow-band imaging instruments; a high resolution spectropolarimeter and an Echelle spectrograph for night time astronomy. This project is led by the Indian Institute of Astrophysics and has national and international partners. Its geographical location will fill the longitudinal gap between Japan and Europe and is expected to be the largest solar telescope with an aperture larger than 1.5 m till the ATST and EST come into operation. An international consortium has been identified to build the NLST. The facility is expected to be commissioned by 2016.

  2. Very Large Scale Integration (VLSI).

    ERIC Educational Resources Information Center

    Yeaman, Andrew R. J.

    Very Large Scale Integration (VLSI), the state-of-the-art production techniques for computer chips, promises such powerful, inexpensive computing that, in the future, people will be able to communicate with computer devices in natural language or even speech. However, before full-scale VLSI implementation can occur, certain salient factors must be…

  3. National Large Solar Telescope of Russia

    NASA Astrophysics Data System (ADS)

    Demidov, Mikhail

    One of the most important task of the modern solar physics is multi-wavelength observations of the small-scale structure of solar atmosphere on different heights, including chromosphere and corona. To do this the large-aperture telescopes are necessary. At present time there several challenging projects of the large (and even giant) solar telescopes in the world are in the process of construction or designing , the most known ones among them are 4-meter class telescopes ATST in USA and EST in Europe. Since 2013 the development of the new Large Solar Telescope (LST) with 3 meter diameter of the main mirror is started in Russia as a part (sub-project) of National Heliogeophysical Complex (NHGC) of the Russian Academy of Sciences. It should be located at the Sayan solar observatory on the altitude more then 2000 m. To avoid numerous problems of the off-axis optical telescopes (despite of the obvious some advantages of the off-axis configuration) and to meet to available financial budget, the classical on-axis Gregorian scheme on the alt-azimuth mount has been chosen. The scientific equipment of the LST-3 will include several narrow-band tunable filter devices and spectrographs for different wavelength bands, including infrared. The units are installed either at the Nasmyth focus or/and on the rotating coude platform. To minimize the instrumental polarization the polarization analyzer is located near diagonal mirror after M2 mirror. High order adaptive optics is used to achieve the diffraction limited performances. It is expected that after some modification of the optical configuration the LST-3 will operate as an approximately 1-m mirror coronograph in the near infrared spectral lines. Possibilities for stellar observations during night time are provided as well.

  4. Galaxy clustering on large scales.

    PubMed

    Efstathiou, G

    1993-06-01

    I describe some recent observations of large-scale structure in the galaxy distribution. The best constraints come from two-dimensional galaxy surveys and studies of angular correlation functions. Results from galaxy redshift surveys are much less precise but are consistent with the angular correlations, provided the distortions in mapping between real-space and redshift-space are relatively weak. The galaxy two-point correlation function, rich-cluster two-point correlation function, and galaxy-cluster cross-correlation function are all well described on large scales ( greater, similar 20h-1 Mpc, where the Hubble constant, H0 = 100h km.s-1.Mpc; 1 pc = 3.09 x 10(16) m) by the power spectrum of an initially scale-invariant, adiabatic, cold-dark-matter Universe with Gamma = Omegah approximately 0.2. I discuss how this fits in with the Cosmic Background Explorer (COBE) satellite detection of large-scale anisotropies in the microwave background radiation and other measures of large-scale structure in the Universe. PMID:11607400

  5. Cross-Scale Coupling in the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro K.

    2011-01-01

    For understanding and eventually predicting solar activity, the fundamental question that Solar-C must answer is: How does energy transfer from the large-scales at which it is injected into the solar atmosphere to the small scales at which it is dissipated? We show that this question of cross-scale coupling is fundamental to all activity, ranging from the smallest nanoflares that are postulated to power coronal heating and solar wind acceleration, to the largest coronal mass ejections and eruptive flares. For the solar atmosphere, the most important process that actually dissipates the energy is believed to be magnetic reconnection. We present results on recent calculations of reconnection in a variety of solar contexts and focus on the coupling between kinetic and MHD scales during reconnection. We discuss the implications of our results for present data and for future observations from Solar-C.

  6. Electro-spray deposition of a mesoporous TiO2 charge collection layer: toward large scale and continuous production of high efficiency perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Min-Cheol; Kim, Byeong Jo; Yoon, Jungjin; Lee, Jin-Wook; Suh, Dongchul; Park, Nam-Gyu; Choi, Mansoo; Jung, Hyun Suk

    2015-12-01

    The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH3NH3PbI3 (MAPbI3), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO2 electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO2 film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO2 films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm2 TiO2 films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH3NH3PbI3 (MAPbI3), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO2 electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO2 film

  7. High-performance large-scale flexible dye-sensitized solar cells based on anodic TiO2 nanotube arrays.

    PubMed

    Jen, Hsiu-Ping; Lin, Meng-Hung; Li, Lu-Lin; Wu, Hui-Ping; Huang, Wei-Kai; Cheng, Po-Jen; Diau, Eric Wei-Guang

    2013-10-23

    A simple strategy to fabricate flexible dye-sensitized solar cells involves the use of photoanodes based on TiO2 nanotube (TNT) arrays with rear illumination. The TNT films (tube length ∼35 μm) were produced via anodization, and sensitized with N719 dye for photovoltaic characterization. Pt counter electrodes of two types were used: a conventional FTO/glass substrate for a device of rigid type and an ITO/PEN substrate for a device of flexible type. These DSSC devices were fabricated into either a single-cell structure (active area 3.6×0.5 cm2) or a parallel module containing three single cells (total active area 5.4 cm2). The flexible devices exhibit remarkable performance with efficiencies η=5.40% (single cell) and 4.77% (parallel module) of power conversion, which outperformed their rigid counterparts with η=4.87% (single cell) and 4.50% (parallel model) under standard one-sun irradiation. The flexible device had a greater efficiency of conversion of incident photons to current and a broader spectral range than the rigid device; a thinner electrolyte layer for the flexible device than for the rigid device is a key factor to improve the light-harvesting ability for the TNT-DSSC device with rear illumination. Measurements of electrochemical impedance spectra show excellent catalytic activity and superior diffusion characteristics for the flexible device. This technique thus provides a new option to construct flexible photovoltaic devices with large-scale, light-weight, and cost-effective advantages for imminent applications in consumer electronics. PMID:24050628

  8. Similarity Rules for Scaling Solar Sail Systems

    NASA Technical Reports Server (NTRS)

    Canfield, Stephen L.; Beard, James W., III; Peddieson, John; Ewing, Anthony; Garbe, Greg

    2004-01-01

    Future science missions will require solar sails on the order 10,000 sq m (or larger). However, ground and flight demonstrations must be conducted at significantly smaller Sizes (400 sq m for ground demo) due to limitations of ground-based facilities and cost and availability of flight opportunities. For this reason, the ability to understand the process of scalability, as it applies to solar sail system models and test data, is crucial to the advancement of this technology. This report will address issues of scaling in solar sail systems, focusing on structural characteristics, by developing a set of similarity or similitude functions that will guide the scaling process. The primary goal of these similarity functions (process invariants) that collectively form a set of scaling rules or guidelines is to establish valid relationships between models and experiments that are performed at different orders of scale. In the near term, such an effort will help guide the size and properties of a flight validation sail that will need to be flown to accurately represent a large, mission-level sail.

  9. Challenges for Large Scale Simulations

    NASA Astrophysics Data System (ADS)

    Troyer, Matthias

    2010-03-01

    With computational approaches becoming ubiquitous the growing impact of large scale computing on research influences both theoretical and experimental work. I will review a few examples in condensed matter physics and quantum optics, including the impact of computer simulations in the search for supersolidity, thermometry in ultracold quantum gases, and the challenging search for novel phases in strongly correlated electron systems. While only a decade ago such simulations needed the fastest supercomputers, many simulations can now be performed on small workstation clusters or even a laptop: what was previously restricted to a few experts can now potentially be used by many. Only part of the gain in computational capabilities is due to Moore's law and improvement in hardware. Equally impressive is the performance gain due to new algorithms - as I will illustrate using some recently developed algorithms. At the same time modern peta-scale supercomputers offer unprecedented computational power and allow us to tackle new problems and address questions that were impossible to solve numerically only a few years ago. While there is a roadmap for future hardware developments to exascale and beyond, the main challenges are on the algorithmic and software infrastructure side. Among the problems that face the computational physicist are: the development of new algorithms that scale to thousands of cores and beyond, a software infrastructure that lifts code development to a higher level and speeds up the development of new simulation programs for large scale computing machines, tools to analyze the large volume of data obtained from such simulations, and as an emerging field provenance-aware software that aims for reproducibility of the complete computational workflow from model parameters to the final figures. Interdisciplinary collaborations and collective efforts will be required, in contrast to the cottage-industry culture currently present in many areas of computational

  10. Predicting large solar flares with data assimilation

    NASA Astrophysics Data System (ADS)

    Strugarek, Antoine; Charbonneau, Paul

    2015-08-01

    Solar and stellar flares are magnetically-driven, scale-invariant energy release events spanning over 8 orders of magnitude in energy. The prediction of the largest solar flares, of class X, is a particularly hard task due the scarcity of such events. The detailed 3D modelling of flaring active regions still requires today too much numerical resources to be routinely used for near real-time predictions. Alternative, empirical models hence have to be designed to perform such predictions. Among the models that adequately reproduce the power-law distribution in flare sizes, avalanche models have the advantage of being numerically cheap to operate. However, they usually rely on a stochastic driver, which can be expected to degrade their predictive capabilities. Building on the pioneering work of Lu and Hamilton, we develop a class of avalanche models which succeed in minimizing the built-in stochastic ingredients while retaining the solar flares power-law distribution. We show that the largest avalanches occurring in these models are robust with respect to the stochastic realization, which opens new perspectives for the prediction of the largest (and most dangerous) solar flares.We further combine data assimilation of the GOES X-ray flux with our avalanche models to carry out actual predictions. The GOES X-ray flux is transformed into a series of peaks that is fed to the model, which automatically finds an initial condition that is compatible with the observed series of events. We then test our prediction model against past GOES large events and discuss the possibility to use our data assimilation package in near real-time applications.

  11. Microfluidic large-scale integration.

    PubMed

    Thorsen, Todd; Maerkl, Sebastian J; Quake, Stephen R

    2002-10-18

    We developed high-density microfluidic chips that contain plumbing networks with thousands of micromechanical valves and hundreds of individually addressable chambers. These fluidic devices are analogous to electronic integrated circuits fabricated using large-scale integration. A key component of these networks is the fluidic multiplexor, which is a combinatorial array of binary valve patterns that exponentially increases the processing power of a network by allowing complex fluid manipulations with a minimal number of inputs. We used these integrated microfluidic networks to construct the microfluidic analog of a comparator array and a microfluidic memory storage device whose behavior resembles random-access memory. PMID:12351675

  12. Large-scale Globally Propagating Coronal Waves

    NASA Astrophysics Data System (ADS)

    Warmuth, Alexander

    2015-09-01

    Large-scale, globally propagating wave-like disturbances have been observed in the solar chromosphere and by inference in the corona since the 1960s. However, detailed analysis of these phenomena has only been conducted since the late 1990s. This was prompted by the availability of high-cadence coronal imaging data from numerous spaced-based instruments, which routinely show spectacular globally propagating bright fronts. Coronal waves, as these perturbations are usually referred to, have now been observed in a wide range of spectral channels, yielding a wealth of information. Many findings have supported the "classical" interpretation of the disturbances: fast-mode MHD waves or shocks that are propagating in the solar corona. However, observations that seemed inconsistent with this picture have stimulated the development of alternative models in which "pseudo waves" are generated by magnetic reconfiguration in the framework of an expanding coronal mass ejection. This has resulted in a vigorous debate on the physical nature of these disturbances. This review focuses on demonstrating how the numerous observational findings of the last one and a half decades can be used to constrain our models of large-scale coronal waves, and how a coherent physical understanding of these disturbances is finally emerging.

  13. Large Scale Nanolaminate Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Miles, R; Chang, K

    2005-11-30

    This work concerns the development of a technology that uses Nanolaminate foils to form light-weight, deformable mirrors that are scalable over a wide range of mirror sizes. While MEMS-based deformable mirrors and spatial light modulators have considerably reduced the cost and increased the capabilities of adaptive optic systems, there has not been a way to utilize the advantages of lithography and batch-fabrication to produce large-scale deformable mirrors. This technology is made scalable by using fabrication techniques and lithography that are not limited to the sizes of conventional MEMS devices. Like many MEMS devices, these mirrors use parallel plate electrostatic actuators. This technology replicates that functionality by suspending a horizontal piece of nanolaminate foil over an electrode by electroplated nickel posts. This actuator is attached, with another post, to another nanolaminate foil that acts as the mirror surface. Most MEMS devices are produced with integrated circuit lithography techniques that are capable of very small line widths, but are not scalable to large sizes. This technology is very tolerant of lithography errors and can use coarser, printed circuit board lithography techniques that can be scaled to very large sizes. These mirrors use small, lithographically defined actuators and thin nanolaminate foils allowing them to produce deformations over a large area while minimizing weight. This paper will describe a staged program to develop this technology. First-principles models were developed to determine design parameters. Three stages of fabrication will be described starting with a 3 x 3 device using conventional metal foils and epoxy to a 10-across all-metal device with nanolaminate mirror surfaces.

  14. Effects of time-dependent large-scale forcing, solar zenith angle, and sea surface temperature on time-mean rainfall: a partitioning analysis based on surface rainfall budget

    NASA Astrophysics Data System (ADS)

    Gao, Shouting; Li, Xiaofan

    2011-06-01

    Effects of time-dependent large-scale forcing, solar zenith angle, and sea surface temperature on time-mean rainfall during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) are examined through a partitioning analysis of a series of sensitivity cloud-resolving model experiment data based on surface rainfall budget. The model is forced by time-dependent large-scale forcing (LSF), solar zenith angle (SZA), and sea surface temperature (SST) in the control experiment and is forced only by either time-dependent LSF, SZA, or SST while others are replaced with their time averages in the sensitivity experiments. The rainfall associated with water vapor divergence and local atmospheric drying and hydrometeor loss/convergence has the largest contribution to total rainfall among eight rainfall types. The largest rainfall contribution is increased in the simulations where either time-dependent LSF, SZA, or SST is replaced with its average, whereas it is decreased in the simulation where COARE-derived large-scale vertical velocity is replaced with zero vertical velocity. The contribution of the rainfall associated with water vapor convergence to total rainfall is decreased in the simulations with time-mean LSF, SZA, and SST, whereas it is increased in the simulation without large-scale vertical velocity.

  15. (abstract) Scaling Nominal Solar Cell Impedances for Array Design

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L; Wallace, Matthew T.; Iles, Peter

    1994-01-01

    This paper discusses a task the objective of which is to characterize solar cell array AC impedance and develop scaling rules for impedance characterization of large arrays by testing single solar cells and small arrays. This effort is aimed at formulating a methodology for estimating the AC impedance of the Mars Pathfinder (MPF) cruise and lander solar arrays based upon testing single cells and small solar cell arrays and to create a basis for design of a single shunt limiter for MPF power control of flight solar arrays having very different inpedances.

  16. The effect of multiple particle sizes on cooling rates of chondrules produced in large-scale shocks in the solar nebula

    NASA Astrophysics Data System (ADS)

    Morris, Melissa A.; Weidenschilling, Stuart J.; Desch, Steven J.

    2016-05-01

    Chondrules represent one of the best probes of the physical conditions and processes acting in the early solar nebula. Proposed chondrule formation models are assessed based on their ability to match the meteoritic evidence, especially experimental constraints on their thermal histories. The model most consistent with chondrule thermal histories is passage through shock waves in the solar nebula. Existing models of heating by shocks generally yield a good first-order approximation to inferred chondrule cooling rates. However, they predict prolonged heating in the preshock region, which would cause volatile loss and isotopic fractionation, which are not observed. These models have typically included particles of a single (large) size, i.e., chondrule precursors, or at most, large particles accompanied by micron-sized grains. The size distribution of solids present during chondrule formation controls the opacity of the affected region, and significantly affects the thermal histories of chondrules. Micron-sized grains evaporate too quickly to prevent excessive heating of chondrule precursors. However, isolated grains in chondrule-forming regions would rapidly coagulate into fractal aggregates. Preshock heating by infrared radiation from the shock front would cause these aggregates to melt and collapse into intermediate-sized (tens of microns) particles. We show that inclusion of such particles yields chondrule cooling rates consistent with petrologic and isotopic constraints.

  17. Large scale topography of Io

    NASA Technical Reports Server (NTRS)

    Gaskell, R. W.; Synnott, S. P.

    1987-01-01

    To investigate the large scale topography of the Jovian satellite Io, both limb observations and stereographic techniques applied to landmarks are used. The raw data for this study consists of Voyager 1 images of Io, 800x800 arrays of picture elements each of which can take on 256 possible brightness values. In analyzing this data it was necessary to identify and locate landmarks and limb points on the raw images, remove the image distortions caused by the camera electronics and translate the corrected locations into positions relative to a reference geoid. Minimizing the uncertainty in the corrected locations is crucial to the success of this project. In the highest resolution frames, an error of a tenth of a pixel in image space location can lead to a 300 m error in true location. In the lowest resolution frames, the same error can lead to an uncertainty of several km.

  18. X6.9-CLASS FLARE-INDUCED VERTICAL KINK OSCILLATIONS IN A LARGE-SCALE PLASMA CURTAIN AS OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Srivastava, A. K.; Goossens, M.

    2013-11-01

    We present rare observational evidence of vertical kink oscillations in a laminar and diffused large-scale plasma curtain as observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The X6.9-class flare in active region 11263 on 2011 August 9 induces a global large-scale disturbance that propagates in a narrow lane above the plasma curtain and creates a low density region that appears as a dimming in the observational image data. This large-scale propagating disturbance acts as a non-periodic driver that interacts asymmetrically and obliquely with the top of the plasma curtain and triggers the observed oscillations. In the deeper layers of the curtain, we find evidence of vertical kink oscillations with two periods (795 s and 530 s). On the magnetic surface of the curtain where the density is inhomogeneous due to coronal dimming, non-decaying vertical oscillations are also observed (period ≈ 763-896 s). We infer that the global large-scale disturbance triggers vertical kink oscillations in the deeper layers as well as on the surface of the large-scale plasma curtain. The properties of the excited waves strongly depend on the local plasma and magnetic field conditions.

  19. Relation of large-scale coronal X-ray structure and cosmic rays. I - Sources of solar wind streams as defined by X-ray emission and H-alpha absorption features

    NASA Technical Reports Server (NTRS)

    Krieger, A. S.; Nolte, J. T.; Sullivan, J. D.; Lazarus, A. J.; Mcintosh, P. S.; Gold, R. E.; Roelof, E. C.

    1975-01-01

    The large-scale structure of the corona and the interplanetary medium during Carrington rotations 1601-1607 is discussed relative to recurrent high-speed solar wind streams and their coronal sources. Only streams A, C, D, and F recur on more than one rotation. Streams A and D are associated with coronal holes, while C and F originate in the high corona (20-50 solar radii) over faint X-ray emissions. The association of the streams with holes is confirmed by earlier findings that there are no large equatorial holes without an associated high-speed stream and that the area of the equatorial region of coronal holes is highly correlated with the maximum velocity observed in the associated stream near 1 AU.

  20. Displacement of large-scale open solar magnetic fields from the zone of active longitudes and the heliospheric storm of November 3-10, 2004: 2. "Explosion" of singularity and dynamics of sunspot formation and energy release

    NASA Astrophysics Data System (ADS)

    Ivanov, K. G.

    2010-12-01

    A more detailed scenario of one stage (August-November 2004) of the quasibiennial MHD process "Origination ... and dissipation of the four-sector structure of the solar magnetic field" during the decline phase of cycle 23 has been constructed. It has been indicated that the following working hypothesis on the propagation of an MHD disturbance westward (in the direction of solar rotation) and eastward (toward the zone of active longitudes) with the displacement of the large-scale open solar magnetic field (LOSMF) from this zone can be constructed based on LOSMF model representations and data on sunspot formation, flares, active filaments, and coronal ejections as well as on the estimated contribution of sporadic energy release to the flare luminosity and kinetic energy of ejections: (1) The "explosion" of the LOSMF singularity and the formation in the explosion zone of an anemone active region (AR), which produced the satellite sunspot formation that continued west and east of the "anemone," represented a powerful and energy-intensive source of MHD processes at this stage. (2) This resulted in the origination of two "governing" large-scale MHD processes, which regulated various usual manifestations of solar activity: the fast LOSMF along the neutral line in the solar atmosphere, strongly affecting the zone of active longitudes, and the slow LOSMF in the outer layers of the convection zone. The fronts of these processes were identified by powerful (about 1031 erg) coronal ejections. (3) The collision of a wave reflected from the zone of active longitudes with the eastern front of the hydromagnetic impulse of the convection zone resulted in an increase in LOSMF magnetic fluxes, origination of an active sector boundary in the zone of active longitudes, shear-convergent motions, and generation and destabilization of the flare-productive AR 10696 responsible for the heliospheric storm of November 3-10, 2004.

  1. Large-Scale Information Systems

    SciTech Connect

    D. M. Nicol; H. R. Ammerlahn; M. E. Goldsby; M. M. Johnson; D. E. Rhodes; A. S. Yoshimura

    2000-12-01

    Large enterprises are ever more dependent on their Large-Scale Information Systems (LSLS), computer systems that are distinguished architecturally by distributed components--data sources, networks, computing engines, simulations, human-in-the-loop control and remote access stations. These systems provide such capabilities as workflow, data fusion and distributed database access. The Nuclear Weapons Complex (NWC) contains many examples of LSIS components, a fact that motivates this research. However, most LSIS in use grew up from collections of separate subsystems that were not designed to be components of an integrated system. For this reason, they are often difficult to analyze and control. The problem is made more difficult by the size of a typical system, its diversity of information sources, and the institutional complexities associated with its geographic distribution across the enterprise. Moreover, there is no integrated approach for analyzing or managing such systems. Indeed, integrated development of LSIS is an active area of academic research. This work developed such an approach by simulating the various components of the LSIS and allowing the simulated components to interact with real LSIS subsystems. This research demonstrated two benefits. First, applying it to a particular LSIS provided a thorough understanding of the interfaces between the system's components. Second, it demonstrated how more rapid and detailed answers could be obtained to questions significant to the enterprise by interacting with the relevant LSIS subsystems through simulated components designed with those questions in mind. In a final, added phase of the project, investigations were made on extending this research to wireless communication networks in support of telemetry applications.

  2. Large Scale Homing in Honeybees

    PubMed Central

    Pahl, Mario; Zhu, Hong; Tautz, Jürgen; Zhang, Shaowu

    2011-01-01

    Honeybee foragers frequently fly several kilometres to and from vital resources, and communicate those locations to their nest mates by a symbolic dance language. Research has shown that they achieve this feat by memorizing landmarks and the skyline panorama, using the sun and polarized skylight as compasses and by integrating their outbound flight paths. In order to investigate the capacity of the honeybees' homing abilities, we artificially displaced foragers to novel release spots at various distances up to 13 km in the four cardinal directions. Returning bees were individually registered by a radio frequency identification (RFID) system at the hive entrance. We found that homing rate, homing speed and the maximum homing distance depend on the release direction. Bees released in the east were more likely to find their way back home, and returned faster than bees released in any other direction, due to the familiarity of global landmarks seen from the hive. Our findings suggest that such large scale homing is facilitated by global landmarks acting as beacons, and possibly the entire skyline panorama. PMID:21602920

  3. Large area space solar cell assemblies

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Nowlan, M. J.

    1982-01-01

    Development of a large area space solar cell assembly is presented. The assembly consists of an ion implanted silicon cell and glass cover. The important attributes of fabrication are (1) use of a back surface field which is compatible with a back surface reflector, and (2) integration of coverglass application and call fabrication.

  4. On Solar-Wind Electron Heating at Large Solar Distances

    NASA Astrophysics Data System (ADS)

    Chashei, Igor V.; Fahr, Hans J.

    2014-04-01

    We study the temperature of electrons advected with the solar wind to large solar distances far beyond 1 AU. Almost nothing is known about the thermodynamics of these electrons from in-situ plasma observations at these distances, and usually it is tacitly assumed that electrons, due to adiabatic behaviour and vanishing heat conduction, rapidly cool off to very low temperatures at larger distances. In this article we show, however, that electrons on their way to large distances undergo non-adiabatic interactions with travelling shocks and solar-wind bulk-velocity jumps and thereby are appreciably heated. Examining this heating process on an average statistical basis, we find that solar-wind electrons first cool down to a temperature minimum, which depending on the occurrence frequency of bulk velocity jumps is located between 3 and 6 AU, but beyond this the lowest electron temperature again starts to increase with increasing solar distance, finally achieving temperatures of about 7×104 K to 7×105 K at the location of the termination shock. Hence these electrons are unexpectedly shown to play an important dynamical role in structuring this shock and in determining the downstream plasma properties.

  5. Large-scale negative polarity magnetic fields on the sun and particle-emitting flares

    NASA Technical Reports Server (NTRS)

    Bumba, V.

    1972-01-01

    Some observational facts about the large-scale patterns formed by solar negative polarity magnetic fields during the 19th and 20th cycles of solar activity are presented. The close relation of the position of occurrence of very large flares accompanied by cosmic ray and PCA events as well as other phenomena of solar activity during the declining part of the 19th cycle of the regularities in the internal structure of large scale negative polarity features are demonstrated.

  6. Similarity Rules for Scaling Solar Sail Systems

    NASA Technical Reports Server (NTRS)

    Canfield, Stephen L.; Peddieson, John; Garbe, Gregory

    2010-01-01

    Future science missions will require solar sails on the order of 200 square meters (or larger). However, ground demonstrations and flight demonstrations must be conducted at significantly smaller sizes, due to limitations of ground-based facilities and cost and availability of flight opportunities. For this reason, the ability to understand the process of scalability, as it applies to solar sail system models and test data, is crucial to the advancement of this technology. This paper will approach the problem of scaling in solar sail models by developing a set of scaling laws or similarity criteria that will provide constraints in the sail design process. These scaling laws establish functional relationships between design parameters of a prototype and model sail that are created at different geometric sizes. This work is applied to a specific solar sail configuration and results in three (four) similarity criteria for static (dynamic) sail models. Further, it is demonstrated that even in the context of unique sail material requirements and gravitational load of earth-bound experiments, it is possible to develop appropriate scaled sail experiments. In the longer term, these scaling laws can be used in the design of scaled experimental tests for solar sails and in analyzing the results from such tests.

  7. PROBING THE HALO FROM THE SOLAR VICINITY TO THE OUTER GALAXY: CONNECTING STARS IN LOCAL VELOCITY STRUCTURES TO LARGE-SCALE CLOUDS

    SciTech Connect

    Johnston, Kathryn V.; Sheffield, Allyson A.; Majewski, Steven R.; Sharma, Sanjib; Rocha-Pinto, Helio J.

    2012-11-20

    This paper presents the first potential connections made between two local features in velocity space found in a survey of M giant stars and stellar spatial inhomogeneities on global scales. Comparison to cosmological, chemodynamical stellar halo models confirms that the M giant population is particularly sensitive to rare, recent and massive accretion events. These events can give rise to locally observed velocity sequences-each made from a small fraction of debris from a massive progenitor, passing at high velocity through the survey volume, near the pericenter of the eccentric orbit of the system. The majority of the debris is found in much larger structures, whose morphologies are more cloud-like than stream-like and which lie at the orbital apocenters. Adopting this interpretation, the full-space motions represented by the observed M giant velocity features are derived under the assumption that the members within each sequence share a common space velocity. Orbit integrations are then used to trace the past and future trajectories of these stars across the sky revealing plausible associations with large, previously discovered, cloud-like structures. The connections made between nearby velocity structures and these distant clouds represent preliminary steps toward developing coherent maps of such giant debris systems. These maps promise to provide new insights into the origin of debris clouds, new probes of Galactic history and structure, and new constraints on the high-velocity tails of the local dark matter distribution that are essential for interpreting direct dark matter particle detection experiments.

  8. The feasibility of large refracting telescopes for solar coronal research

    NASA Astrophysics Data System (ADS)

    Nelson, Peter G.; Tomczyk, Steven; Elmore, David F.; Kolinski, Donald J.

    2008-07-01

    Measuring magnetic fields in the solar corona requires a large aperture telescope with exceptionally low levels of scattered light. For internally-occulted coronagraphs the main source is scattering from dust or microroughness on the primary lens or mirror. We show refracting primaries offer significantly lower levels for both sources. To observe magnetic fields in the solar corona with scientifically interesting spatial and temporal resolutions, a 1 meter aperture or larger is required. For a long time such large-scale refractors have been deemed impractical or impossible to construct due to gravitational deformation of the lens. We present the results of finite-element and optical analyses of the gravitational deformation, stress-induced birefringence, and absorptive heating of a (see manuscript)1.5 meter f/5 fused silica lens. These studies demonstrate the traditional objections to large refractors are unfounded and large refracting primaries have unique capabilities.

  9. Solar Wind Variability: from Macro to Micro Scales

    NASA Astrophysics Data System (ADS)

    Bruno, R.

    2015-12-01

    Several decades of in-situ observations by spacecraft unraveled the complex nature of the variability of solar wind magnetic field and plasma parameters. These fluctuations range from scales of the order of the solar rotation period to the smallest scales of the order of the ion and electron characteristic scale lengths. Some of these fluctuations belong to coronal transients, others to propagating modes and others are simply due to inhomogeneities and structures advected by the wind across the observer. In this talk I'll provide a short overview of the state of art of our current interpretation of the complex phenomenology observed so far, also in view of the next solar missions Solar Orbiter and SPP. I will start describing the solar wind large scale structure and its connection to the low corona. I will continue through the MHD regime, where turbulence energy is nonlinearly transferred to smaller and smaller scales, to end up at kinetic scales where this energy eventually is dissipated.

  10. LEMUR: Large European Module for Solar Ultraviolet Research

    NASA Technical Reports Server (NTRS)

    Teriaca, Luca; Vincenzo, Andretta; Auchere, Frederic; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martinez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schuhle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter

    2012-01-01

    The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Angstrom and 1270 Angstrom. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution

  11. Large-Scale Reform Comes of Age

    ERIC Educational Resources Information Center

    Fullan, Michael

    2009-01-01

    This article reviews the history of large-scale education reform and makes the case that large-scale or whole system reform policies and strategies are becoming increasingly evident. The review briefly addresses the pre 1997 period concluding that while the pressure for reform was mounting that there were very few examples of deliberate or…

  12. Large-scale infrared scene projectors

    NASA Astrophysics Data System (ADS)

    Murray, Darin A.

    1999-07-01

    Large-scale infrared scene projectors, typically have unique opto-mechanical characteristics associated to their application. This paper outlines two large-scale zoom lens assemblies with different environmental and package constraints. Various challenges and their respective solutions are discussed and presented.

  13. Synthesis of small and large scale dynamos

    NASA Astrophysics Data System (ADS)

    Subramanian, Kandaswamy

    Using a closure model for the evolution of magnetic correlations, we uncover an interesting plausible saturated state of the small-scale fluctuation dynamo (SSD) and a novel analogy between quantum mechanical tunnelling and the generation of large-scale fields. Large scale fields develop via the α-effect, but as magnetic helicity can only change on a resistive timescale, the time it takes to organize the field into large scales increases with magnetic Reynolds number. This is very similar to the results which obtain from simulations using the full MHD equations.

  14. Large-scale inhomogeneities and galaxy statistics

    NASA Technical Reports Server (NTRS)

    Schaeffer, R.; Silk, J.

    1984-01-01

    The density fluctuations associated with the formation of large-scale cosmic pancake-like and filamentary structures are evaluated using the Zel'dovich approximation for the evolution of nonlinear inhomogeneities in the expanding universe. It is shown that the large-scale nonlinear density fluctuations in the galaxy distribution due to pancakes modify the standard scale-invariant correlation function xi(r) at scales comparable to the coherence length of adiabatic fluctuations. The typical contribution of pancakes and filaments to the J3 integral, and more generally to the moments of galaxy counts in a volume of approximately (15-40 per h Mpc)exp 3, provides a statistical test for the existence of large scale inhomogeneities. An application to several recent three dimensional data sets shows that despite large observational uncertainties over the relevant scales characteristic features may be present that can be attributed to pancakes in most, but not all, of the various galaxy samples.

  15. Transient flows of the solar wind associated with small-scale solar activity in solar minimum

    NASA Astrophysics Data System (ADS)

    Slemzin, Vladimir; Veselovsky, Igor; Kuzin, Sergey; Gburek, Szymon; Ulyanov, Artyom; Kirichenko, Alexey; Shugay, Yulia; Goryaev, Farid

    The data obtained by the modern high sensitive EUV-XUV telescopes and photometers such as CORONAS-Photon/TESIS and SPHINX, STEREO/EUVI, PROBA2/SWAP, SDO/AIA provide good possibilities for studying small-scale solar activity (SSA), which is supposed to play an important role in heating of the corona and producing transient flows of the solar wind. During the recent unusually weak solar minimum, a large number of SSA events, such as week solar flares, small CMEs and CME-like flows were observed and recorded in the databases of flares (STEREO, SWAP, SPHINX) and CMEs (LASCO, CACTUS). On the other hand, the solar wind data obtained in this period by ACE, Wind, STEREO contain signatures of transient ICME-like structures which have shorter duration (<10h), weaker magnetic field strength (<10 nT) and lower proton temperature than usual ICMEs. To verify the assumption that ICME-like transients may be associated with the SSA events we investigated the number of weak flares of C-class and lower detected by SPHINX in 2009 and STEREO/EUVI in 2010. The flares were classified on temperature and emission measure using the diagnostic means of SPHINX and Hinode/EIS and were confronted with the parameters of the solar wind (velocity, density, ion composition and temperature, magnetic field, pitch angle distribution of the suprathermal electrons). The outflows of plasma associated with the flares were identified by their coronal signatures - CMEs (only in few cases) and dimmings. It was found that the mean parameters of the solar wind projected to the source surface for the times of the studied flares were typical for the ICME-like transients. The results support the suggestion that weak flares can be indicators of sources of transient plasma flows contributing to the slow solar wind at solar minimum, although these flows may be too weak to be considered as separate CMEs and ICMEs. The research leading to these results has received funding from the European Union’s Seventh Programme

  16. Large-scale micro- and nanopatterns of Cu(In,Ga)Se2 thin film solar cells by mold-assisted chemical-etching process.

    PubMed

    Wang, Yi-Chung; Cheng, Hsiang-Ying; Yen, Yu-Ting; Wu, Tsung-Ta; Hsu, Cheng-Hung; Tsai, Hung-Wei; Shen, Chang-Hong; Shieh, Jia-Min; Chueh, Yu-Lun

    2015-04-28

    A reactive mold-assisted chemical etching (MACE) process through an easy-to-make agarose stamp soaked in bromine methanol etchant to rapidly imprint larger area micro- and nanoarrays on CIGS substrates was demonstrated. Interestingly, by using the agarose stamp during the MACE process with and without additive containing oil and triton, CIGS microdome and microhole arrays can be formed on the CIGS substrate. Detailed formation mechanisms of microstructures and the chemical composition variation after the etching process were investigated. In addition, various microand nanostructures were also demonstrated by this universal approach. The microstructure arrays integrated into standard CIGS solar cells with thinner thickness can still achieve an efficiency of 11.22%, yielding an enhanced efficiency of ∼18% compared with that of their planar counterpart due to an excellent absorption behavior confirmed by the simulation results, which opens up a promising way for the realization of high-efficiency micro- or nanostructured thin-film solar cells. Finally, the complete dissolution of agarose stamp into hot water demonstrates an environmentally friendly method by the mold-assisted chemical etching process through an easy-to-make agarose stamp. PMID:25769317

  17. Large-Scale PV Module Manufacturing Using Ultra-Thin Polycrystalline Silicon Solar Cells: Final Subcontract Report, 1 April 2002--28 February 2006

    SciTech Connect

    Wohlgemuth, J.; Narayanan, M.

    2006-07-01

    The major objectives of this program were to continue advances of BP Solar polycrystalline silicon manufacturing technology. The Program included work in the following areas. (1) Efforts in the casting area to increase ingot size, improve ingot material quality, and improve handling of silicon feedstock as it is loaded into the casting stations. (2) Developing wire saws to slice 100-..mu..m-thick silicon wafers on 290-..mu..m-centers. (3) Developing equipment for demounting and subsequent handling of very thin silicon wafers. (4) Developing cell processes using 100-..mu..m-thick silicon wafers that produce encapsulated cells with efficiencies of at least 15.4% at an overall yield exceeding 95%. (5) Expanding existing in-line manufacturing data reporting systems to provide active process control. (6) Establishing a 50-MW (annual nominal capacity) green-field Mega-plant factory model template based on this new thin polycrystalline silicon technology. (7) Facilitating an increase in the silicon feedstock industry's production capacity for lower-cost solar-grade silicon feedstock..

  18. The large-scale landslide risk classification in catchment scale

    NASA Astrophysics Data System (ADS)

    Liu, Che-Hsin; Wu, Tingyeh; Chen, Lien-Kuang; Lin, Sheng-Chi

    2013-04-01

    The landslide disasters caused heavy casualties during Typhoon Morakot, 2009. This disaster is defined as largescale landslide due to the casualty numbers. This event also reflects the survey on large-scale landslide potential is so far insufficient and significant. The large-scale landslide potential analysis provides information about where should be focused on even though it is very difficult to distinguish. Accordingly, the authors intend to investigate the methods used by different countries, such as Hong Kong, Italy, Japan and Switzerland to clarify the assessment methodology. The objects include the place with susceptibility of rock slide and dip slope and the major landslide areas defined from historical records. Three different levels of scales are confirmed necessarily from country to slopeland, which are basin, catchment, and slope scales. Totally ten spots were classified with high large-scale landslide potential in the basin scale. The authors therefore focused on the catchment scale and employ risk matrix to classify the potential in this paper. The protected objects and large-scale landslide susceptibility ratio are two main indexes to classify the large-scale landslide risk. The protected objects are the constructions and transportation facilities. The large-scale landslide susceptibility ratio is based on the data of major landslide area and dip slope and rock slide areas. Totally 1,040 catchments are concerned and are classified into three levels, which are high, medium, and low levels. The proportions of high, medium, and low levels are 11%, 51%, and 38%, individually. This result represents the catchments with high proportion of protected objects or large-scale landslide susceptibility. The conclusion is made and it be the base material for the slopeland authorities when considering slopeland management and the further investigation.

  19. Survey on large scale system control methods

    NASA Technical Reports Server (NTRS)

    Mercadal, Mathieu

    1987-01-01

    The problem inherent to large scale systems such as power network, communication network and economic or ecological systems were studied. The increase in size and flexibility of future spacecraft has put those dynamical systems into the category of large scale systems, and tools specific to the class of large systems are being sought to design control systems that can guarantee more stability and better performance. Among several survey papers, reference was found to a thorough investigation on decentralized control methods. Especially helpful was the classification made of the different existing approaches to deal with large scale systems. A very similar classification is used, even though the papers surveyed are somehow different from the ones reviewed in other papers. Special attention is brought to the applicability of the existing methods to controlling large mechanical systems like large space structures. Some recent developments are added to this survey.

  20. Large-scale regions of antimatter

    SciTech Connect

    Grobov, A. V. Rubin, S. G.

    2015-07-15

    Amodified mechanism of the formation of large-scale antimatter regions is proposed. Antimatter appears owing to fluctuations of a complex scalar field that carries a baryon charge in the inflation era.

  1. Probing Solar Wind Turbulence with the Jansky Very Large Array

    NASA Astrophysics Data System (ADS)

    Kobelski, A.; Bastian, T. S.; Betti, S.

    2016-04-01

    The solar wind offers an extraordinary laboratory for studying MHD turbulence, turbulent dissipation, and heating. Radio propagation phenomena can be exploited as probes of the solar wind in regions that are generally inaccessible to in situ spacecraft measurements. Here, we have undertaken a study with the Jansky Very Large Array (VLA) to observe point-like sources drawn from the JVAS catalog, and 3 VLA calibrator sources, to trans-illuminate the outer corona/inner solar wind. In doing so, we will exploit angular broadening and refractive scintillation to deduce properties of the solar wind along ≍23 lines of sight within 7 solar radii of the Sun and a wide range of position angles. By fitting the complex visibilities using well-known techniques we can deduce or constrain a number of key parameters. In particular, we fit the visibilities to a function of the known source flux, displacement of the source due to refraction, source broadening due to an elliptical structure function, spectral slope of the turbulence, and the coherence scale. Of particular interest is α, the spectral slope of the turbulence which we probe at both small (km to 10s of km) and large (thousands of km) scales. This will help us determine the presence and evolution of an inner scale, measure the degree of anisotropy, and constrain the topology of the global coronal magnetic field. The inner scale is of particular interest for constraining current theories of turbulence dissipation and heating. Initial analysis show the visibilities vary notably on timescales of individual integrations (2 seconds) and that the source is not uniformly broadened. All sources appear to preferentially broaden perpendicular to the magnetic field, consistent with theories of kinetic Alfvén waves. This type of observation will also help to interpret data from the upcoming Solar Probe Plus and Solar Orbiter missions. A full set of results and analysis is forthcoming. More details on previous results can be found

  2. Unification and large-scale structure.

    PubMed Central

    Laing, R A

    1995-01-01

    The hypothesis of relativistic flow on parsec scales, coupled with the symmetrical (and therefore subrelativistic) outer structure of extended radio sources, requires that jets decelerate on scales observable with the Very Large Array. The consequences of this idea for the appearances of FRI and FRII radio sources are explored. PMID:11607609

  3. AMC EN-1038: Reduced scale solar simulator supplementary test report

    NASA Technical Reports Server (NTRS)

    Biering, Robert C.

    1994-01-01

    The reduced scale solar simulator program conducted by the Advanced Manufacturing Center at Cleveland State University in 1992 provided sufficient data to support the selection of the uniform magnification solar simulator module for the Solar Dynamic Ground Test Demonstrator Program (SDGTD) at NASA LeRC. In 1993, additional testing of the reduced scale solar simulator was conducted to provide information to refine and improve the design of the full scale solar simulator. This report presents the results of these additional tests.

  4. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1994-01-01

    The Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, CA, occupies an area measuring about 3 m wide x 12 m long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than plus or minus 2 percent uniformity of irradiance at the test plane and better than plus or minus 0.3 percent measurement repeatability after warm-up. Glass absorption filters reduce the ultraviolet light emitted from the xenon flash lamps. This results in a close match to three different standard airmass zero and airmass 1.5 spectral irradiances. The 2-ms light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices. Since the original printing of this publication, in 1993, the LAPSS has been operational and new capabilities have been added. This revision includes a new section relating to the installation of a method to measure the I-V curve of a solar cell or array exhibiting a large effective capacitance. Another new section has been added relating to new capabilities for plotting single and multiple I-V curves, and for archiving the I-V data and test parameters. Finally, a section has been added regarding the data acquisition electronics calibration.

  5. Structural concepts for large solar concentrators

    NASA Technical Reports Server (NTRS)

    Hedgepeth, John M.; Miller, Richard K.

    1987-01-01

    The Sunflower large solar concentrator, developed in the early 1970's, is a salient example of a high-efficiency concentrator. The newly emphasized needs for solar dynamic power on the Space Station and for large, lightweight thermal sources are outlined. Existing concepts for high efficiency reflector surfaces are examined with attention to accuracy needs for concentration rates of 1000 to 3000. Concepts using stiff reflector panels are deemed most likely to exhibit the long-term consistent accuracy necessary for low-orbit operation, particularly for the higher concentration ratios. Quantitative results are shown of the effects of surface errors for various concentration and focal-length diameter ratios. Cost effectiveness is discussed. Principal sources of high cost include the need for various dished panels for paraboloidal reflectors and the expense of ground testing and adjustment. A new configuration is presented addressing both problems, i.e., a deployable Pactruss backup structure with identical panels installed on the structure after deployment in space. Analytical results show that with reasonable pointing errors, this new concept is capable of concentration ratios greater than 2000.

  6. ANALYSIS OF CHARACTERISTIC PARAMETERS OF LARGE-SCALE CORONAL WAVES OBSERVED BY THE SOLAR-TERRESTRIAL RELATIONS OBSERVATORY/EXTREME ULTRAVIOLET IMAGER

    SciTech Connect

    Muhr, N.; Veronig, A. M.; Kienreich, I. W.; Temmer, M.; Vrsnak, B.

    2011-10-01

    The kinematical evolution of four extreme ultraviolet waves, well observed by the Extreme Ultraviolet Imager on board the Solar-Terrestrial Relations Observatory (STEREO), is studied by visually tracking wave fronts as well as by a semi-automatized perturbation profile method, which leads to results matching each other within the error limits. The derived mean velocities of the events under study lie in the range of 220-350 km s{sup -1}. The fastest of the events (2007 May 19) reveals a significant deceleration of {approx} - 190 m s{sup -2}, while the others are consistent with a constant velocity during wave propagation. The evolution of maximum-intensity values reveals initial intensification of 20%-70% and decays to original levels within 40-60 minutes, while the widths at half-maximum and full-maximum of the perturbation profiles broaden by a factor of two to four. The integral below the perturbation profile remains basically constant in two cases, while it shows a decrease by a factor of three to four in the other two cases. From the peak perturbation amplitudes, we estimate the corresponding magnetosonic Mach numbers M{sub ms}, which range from 1.08-1.21. The perturbation profiles reveal three distinct features behind the propagating wave fronts: coronal dimmings, stationary brightenings, and rarefaction regions. All features appear after the wave passage and only slowly fade away. Our findings indicate that the events under study are weak-shock fast-mode magnetohydrodynamic waves initiated by the CME lateral expansion.

  7. Evaluating Large-Scale Interactive Radio Programmes

    ERIC Educational Resources Information Center

    Potter, Charles; Naidoo, Gordon

    2009-01-01

    This article focuses on the challenges involved in conducting evaluations of interactive radio programmes in South Africa with large numbers of schools, teachers, and learners. It focuses on the role such large-scale evaluation has played during the South African radio learning programme's development stage, as well as during its subsequent…

  8. ARPACK: Solving large scale eigenvalue problems

    NASA Astrophysics Data System (ADS)

    Lehoucq, Rich; Maschhoff, Kristi; Sorensen, Danny; Yang, Chao

    2013-11-01

    ARPACK is a collection of Fortran77 subroutines designed to solve large scale eigenvalue problems. The package is designed to compute a few eigenvalues and corresponding eigenvectors of a general n by n matrix A. It is most appropriate for large sparse or structured matrices A where structured means that a matrix-vector product w

  9. LEMUR: Large European module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission

    NASA Astrophysics Data System (ADS)

    Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter

    2012-10-01

    The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar

  10. Large-scale assembly of colloidal particles

    NASA Astrophysics Data System (ADS)

    Yang, Hongta

    This study reports a simple, roll-to-roll compatible coating technology for producing three-dimensional highly ordered colloidal crystal-polymer composites, colloidal crystals, and macroporous polymer membranes. A vertically beveled doctor blade is utilized to shear align silica microsphere-monomer suspensions to form large-area composites in a single step. The polymer matrix and the silica microspheres can be selectively removed to create colloidal crystals and self-standing macroporous polymer membranes. The thickness of the shear-aligned crystal is correlated with the viscosity of the colloidal suspension and the coating speed, and the correlations can be qualitatively explained by adapting the mechanisms developed for conventional doctor blade coating. Five important research topics related to the application of large-scale three-dimensional highly ordered macroporous films by doctor blade coating are covered in this study. The first topic describes the invention in large area and low cost color reflective displays. This invention is inspired by the heat pipe technology. The self-standing macroporous polymer films exhibit brilliant colors which originate from the Bragg diffractive of visible light form the three-dimensional highly ordered air cavities. The colors can be easily changed by tuning the size of the air cavities to cover the whole visible spectrum. When the air cavities are filled with a solvent which has the same refractive index as that of the polymer, the macroporous polymer films become completely transparent due to the index matching. When the solvent trapped in the cavities is evaporated by in-situ heating, the sample color changes back to brilliant color. This process is highly reversible and reproducible for thousands of cycles. The second topic reports the achievement of rapid and reversible vapor detection by using 3-D macroporous photonic crystals. Capillary condensation of a condensable vapor in the interconnected macropores leads to the

  11. Stratospheric effects of solar ultraviolet variations on the solar rotation time scale

    NASA Technical Reports Server (NTRS)

    Hood, L. L.

    1989-01-01

    A summary is presented of some current work on measurement and interpretation of stratospheric ozone and temperature responses to observed short term solar ultraviolet variations. Although some studies have yielded provisional evidence for a nearly in-phase ozone-solar cycle relationship, they extend at most over only one or two 11 year cycles so the statistical significance of the correlations is not large. Similarly, the relatively short lengths of individual satellite data sets combined with the problem of estimating the effect of changes in instrument sensitivity (drift) during the observing period have complicated attempts to infer long term or solar cycle ozone trends. The solar rotation and active region development time scale provides an alternate time scale for which detailed studies of middle atmospheric ozone and temperature responses to solar ultraviolet variability are currently possible using available satellite data sets. At tropical latitudes where planetary wave amplitudes are relatively small, clear correlative evidence for the existence of middle atmospheric ozone and temperature responses to short term solar ultraviolet variations has been obtained in recent years. These measurements will ultimately allow improved empirical and theoretical calculations of longer term solar induced ozone and temperature variations at low and middle latitudes.

  12. Large-scale simulations of reionization

    SciTech Connect

    Kohler, Katharina; Gnedin, Nickolay Y.; Hamilton, Andrew J.S.; /JILA, Boulder

    2005-11-01

    We use cosmological simulations to explore the large-scale effects of reionization. Since reionization is a process that involves a large dynamic range--from galaxies to rare bright quasars--we need to be able to cover a significant volume of the universe in our simulation without losing the important small scale effects from galaxies. Here we have taken an approach that uses clumping factors derived from small scale simulations to approximate the radiative transfer on the sub-cell scales. Using this technique, we can cover a simulation size up to 1280h{sup -1} Mpc with 10h{sup -1} Mpc cells. This allows us to construct synthetic spectra of quasars similar to observed spectra of SDSS quasars at high redshifts and compare them to the observational data. These spectra can then be analyzed for HII region sizes, the presence of the Gunn-Peterson trough, and the Lyman-{alpha} forest.

  13. "Cosmological Parameters from Large Scale Structure"

    NASA Technical Reports Server (NTRS)

    Hamilton, A. J. S.

    2005-01-01

    This grant has provided primary support for graduate student Mark Neyrinck, and some support for the PI and for colleague Nick Gnedin, who helped co-supervise Neyrinck. This award had two major goals. First, to continue to develop and apply methods for measuring galaxy power spectra on large, linear scales, with a view to constraining cosmological parameters. And second, to begin try to understand galaxy clustering at smaller. nonlinear scales well enough to constrain cosmology from those scales also. Under this grant, the PI and collaborators, notably Max Tegmark. continued to improve their technology for measuring power spectra from galaxy surveys at large, linear scales. and to apply the technology to surveys as the data become available. We believe that our methods are best in the world. These measurements become the foundation from which we and other groups measure cosmological parameters.

  14. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1993-01-01

    A Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, California, occupies an area measuring about 3 meters wide by 12 meters long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than +/- 2 percent uniformity of irradiance at the test plane and better than +/- 0.3 percent measurement repeatability after warm-up. Glass absorption filters are used to reduce the level of ultraviolet light emitted from the xenon flash lamps. This provides a close match to standard airmass zero and airmass 1.5 spectral irradiance distributions. The 2 millisecond light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices.

  15. The large-scale distribution of galaxies

    NASA Technical Reports Server (NTRS)

    Geller, Margaret J.

    1989-01-01

    The spatial distribution of galaxies in the universe is characterized on the basis of the six completed strips of the Harvard-Smithsonian Center for Astrophysics redshift-survey extension. The design of the survey is briefly reviewed, and the results are presented graphically. Vast low-density voids similar to the void in Bootes are found, almost completely surrounded by thin sheets of galaxies. Also discussed are the implications of the results for the survey sampling problem, the two-point correlation function of the galaxy distribution, the possibility of detecting large-scale coherent flows, theoretical models of large-scale structure, and the identification of groups and clusters of galaxies.

  16. Variations in solar Lyman alpha irradiance on short time scales

    NASA Technical Reports Server (NTRS)

    Pap, J. M.

    1992-01-01

    Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

  17. Solar Rejection Filter for Large Telescopes

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James

    2009-01-01

    To reject solar radiation photons at the front aperture for large telescopes, a mosaic of large transmission mode filters is placed in front of the telescope or at the aperture of the dome. Filtering options for effective rejection of sunlight include a smaller filter down-path near the focus of the telescope, and a large-diameter filter located in the front of the main aperture. Two types of large filters are viable: reflectance mode and transmittance mode. In the case of reflectance mode, a dielectric coating on a suitable substrate (e.g. a low-thermal-expansion glass) is arranged to reflect only a single, narrow wavelength and to efficiently transmit all other wavelengths. These coatings are commonly referred to as notch filter. In this case, the large mirror located in front of the telescope aperture reflects the received (signal and background) light into the telescope. In the case of transmittance mode, a dielectric coating on a suitable substrate (glass, sapphire, clear plastic, membrane, and the like) is arranged to transmit only a single wavelength and to reject all other wavelengths (visible and near IR) of light. The substrate of the large filter will determine its mass. At first glance, a large optical filter with a diameter of up to 10 m, located in front of the main aperture, would require a significant thickness to avoid sagging. However, a segmented filter supported by a structurally rugged grid can support smaller filters. The obscuration introduced by the grid is minimal because the total area can be made insignificant. This configuration can be detrimental to a diffraction- limited telescope due to diffraction effects at the edges of each sub-panel. However, no discernable degradation would result for a 20 diffraction-limit telescope (a photon bucket). Even the small amount of sagging in each subpanel should have minimal effect in the performance of a non-diffraction limited telescope because the part has no appreciable optical power. If the

  18. Nearly incompressible fluids: hydrodynamics and large scale inhomogeneity.

    PubMed

    Hunana, P; Zank, G P; Shaikh, D

    2006-08-01

    A system of hydrodynamic equations in the presence of large-scale inhomogeneities for a high plasma beta solar wind is derived. The theory is derived under the assumption of low turbulent Mach number and is developed for the flows where the usual incompressible description is not satisfactory and a full compressible treatment is too complex for any analytical studies. When the effects of compressibility are incorporated only weakly, a new description, referred to as "nearly incompressible hydrodynamics," is obtained. The nearly incompressible theory, was originally applied to homogeneous flows. However, large-scale gradients in density, pressure, temperature, etc., are typical in the solar wind and it was unclear how inhomogeneities would affect the usual incompressible and nearly incompressible descriptions. In the homogeneous case, the lowest order expansion of the fully compressible equations leads to the usual incompressible equations, followed at higher orders by the nearly incompressible equations, as introduced by Zank and Matthaeus. With this work we show that the inclusion of large-scale inhomogeneities (in this case time-independent and radially symmetric background solar wind) modifies the leading-order incompressible description of solar wind flow. We find, for example, that the divergence of velocity fluctuations is nonsolenoidal and that density fluctuations can be described to leading order as a passive scalar. Locally (for small lengthscales), this system of equations converges to the usual incompressible equations and we therefore use the term "locally incompressible" to describe the equations. This term should be distinguished from the term "nearly incompressible," which is reserved for higher-order corrections. Furthermore, we find that density fluctuations scale with Mach number linearly, in contrast to the original homogeneous nearly incompressible theory, in which density fluctuations scale with the square of Mach number. Inhomogeneous nearly

  19. Management of large-scale technology

    NASA Technical Reports Server (NTRS)

    Levine, A.

    1985-01-01

    Two major themes are addressed in this assessment of the management of large-scale NASA programs: (1) how a high technology agency was a decade marked by a rapid expansion of funds and manpower in the first half and almost as rapid contraction in the second; and (2) how NASA combined central planning and control with decentralized project execution.

  20. A Large Scale Computer Terminal Output Controller.

    ERIC Educational Resources Information Center

    Tucker, Paul Thomas

    This paper describes the design and implementation of a large scale computer terminal output controller which supervises the transfer of information from a Control Data 6400 Computer to a PLATO IV data network. It discusses the cost considerations leading to the selection of educational television channels rather than telephone lines for…

  1. Large Scale Commodity Clusters for Lattice QCD

    SciTech Connect

    A. Pochinsky; W. Akers; R. Brower; J. Chen; P. Dreher; R. Edwards; S. Gottlieb; D. Holmgren; P. Mackenzie; J. Negele; D. Richards; J. Simone; W. Watson

    2002-06-01

    We describe the construction of large scale clusters for lattice QCD computing being developed under the umbrella of the U.S. DoE SciDAC initiative. We discuss the study of floating point and network performance that drove the design of the cluster, and present our plans for future multi-Terascale facilities.

  2. Large-scale CFB combustion demonstration project

    SciTech Connect

    Nielsen, P.T.; Hebb, J.L.; Aquino, R.

    1998-07-01

    The Jacksonville Electric Authority's large-scale CFB demonstration project is described. Given the early stage of project development, the paper focuses on the project organizational structure, its role within the Department of Energy's Clean Coal Technology Demonstration Program, and the projected environmental performance. A description of the CFB combustion process in included.

  3. Large-scale CFB combustion demonstration project

    SciTech Connect

    Nielsen, P.T.; Hebb, J.L.; Aquino, R.

    1998-04-01

    The Jacksonville Electric Authority`s large-scale CFB demonstration project is described. Given the early stage of project development, the paper focuses on the project organizational structure, its role within the Department of Energy`s Clean Coal Technology Demonstration Program, and the projected environmental performance. A description of the CFB combustion process is included.

  4. Experimental Simulations of Large-Scale Collisions

    NASA Technical Reports Server (NTRS)

    Housen, Kevin R.

    2002-01-01

    This report summarizes research on the effects of target porosity on the mechanics of impact cratering. Impact experiments conducted on a centrifuge provide direct simulations of large-scale cratering on porous asteroids. The experiments show that large craters in porous materials form mostly by compaction, with essentially no deposition of material into the ejecta blanket that is a signature of cratering in less-porous materials. The ratio of ejecta mass to crater mass is shown to decrease with increasing crater size or target porosity. These results are consistent with the observation that large closely-packed craters on asteroid Mathilde appear to have formed without degradation to earlier craters.

  5. Large-Scale Structures of Planetary Systems

    NASA Astrophysics Data System (ADS)

    Murray-Clay, Ruth; Rogers, Leslie A.

    2015-12-01

    A class of solar system analogs has yet to be identified among the large crop of planetary systems now observed. However, since most observed worlds are more easily detectable than direct analogs of the Sun's planets, the frequency of systems with structures similar to our own remains unknown. Identifying the range of possible planetary system architectures is complicated by the large number of physical processes that affect the formation and dynamical evolution of planets. I will present two ways of organizing planetary system structures. First, I will suggest that relatively few physical parameters are likely to differentiate the qualitative architectures of different systems. Solid mass in a protoplanetary disk is perhaps the most obvious possible controlling parameter, and I will give predictions for correlations between planetary system properties that we would expect to be present if this is the case. In particular, I will suggest that the solar system's structure is representative of low-metallicity systems that nevertheless host giant planets. Second, the disk structures produced as young stars are fed by their host clouds may play a crucial role. Using the observed distribution of RV giant planets as a function of stellar mass, I will demonstrate that invoking ice lines to determine where gas giants can form requires fine tuning. I will suggest that instead, disk structures built during early accretion have lasting impacts on giant planet distributions, and disk clean-up differentially affects the orbital distributions of giant and lower-mass planets. These two organizational hypotheses have different implications for the solar system's context, and I will suggest observational tests that may allow them to be validated or falsified.

  6. Large-scale extraction of proteins.

    PubMed

    Cunha, Teresa; Aires-Barros, Raquel

    2002-01-01

    The production of foreign proteins using selected host with the necessary posttranslational modifications is one of the key successes in modern biotechnology. This methodology allows the industrial production of proteins that otherwise are produced in small quantities. However, the separation and purification of these proteins from the fermentation media constitutes a major bottleneck for the widespread commercialization of recombinant proteins. The major production costs (50-90%) for typical biological product resides in the purification strategy. There is a need for efficient, effective, and economic large-scale bioseparation techniques, to achieve high purity and high recovery, while maintaining the biological activity of the molecule. Aqueous two-phase systems (ATPS) allow process integration as simultaneously separation and concentration of the target protein is achieved, with posterior removal and recycle of the polymer. The ease of scale-up combined with the high partition coefficients obtained allow its potential application in large-scale downstream processing of proteins produced by fermentation. The equipment and the methodology for aqueous two-phase extraction of proteins on a large scale using mixer-settlerand column contractors are described. The operation of the columns, either stagewise or differential, are summarized. A brief description of the methods used to account for mass transfer coefficients, hydrodynamics parameters of hold-up, drop size, and velocity, back mixing in the phases, and flooding performance, required for column design, is also provided. PMID:11876297

  7. Plasma beta control of scaling of solar wind turbulent structures

    NASA Astrophysics Data System (ADS)

    Safrankova, Jana; Nemecek, Zdenek; Nemec, Frantisek; Prech, Lubomir; Chen, Christopher H. K.; Zastenker, Georgy N.

    2016-04-01

    The high-time resolution of Spektr-R plasma measurements allows us to make direct observations of solar wind turbulence below ion kinetic length scales. The paper analyzes solar wind power spectra of bulk and thermal speeds that are computed with a time resolution of 32 ms in the frequency range of 0.001-2 Hz. The statistics based on more than 5000 of individual spectra shows that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectra fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the segment attributed to the MHD scale are ‑1.43 and ‑1.38, respectively for the bulk and thermal speeds, whereas those in the kinetic scale are ‑3.08 and ‑2.43, respectively; (4) the break between both MHD and kinetic scales is controlled the ion beta; and (5) the power index corresponding to kinetic turbulence depends on a level of the density variations in the high beta solar wind, whereas the ion gyromotion determines it for low beta intervals.

  8. Large-Scale PV Integration Study

    SciTech Connect

    Lu, Shuai; Etingov, Pavel V.; Diao, Ruisheng; Ma, Jian; Samaan, Nader A.; Makarov, Yuri V.; Guo, Xinxin; Hafen, Ryan P.; Jin, Chunlian; Kirkham, Harold; Shlatz, Eugene; Frantzis, Lisa; McClive, Timothy; Karlson, Gregory; Acharya, Dhruv; Ellis, Abraham; Stein, Joshua; Hansen, Clifford; Chadliev, Vladimir; Smart, Michael; Salgo, Richard; Sorensen, Rahn; Allen, Barbara; Idelchik, Boris

    2011-07-29

    This research effort evaluates the impact of large-scale photovoltaic (PV) and distributed generation (DG) output on NV Energy’s electric grid system in southern Nevada. It analyzes the ability of NV Energy’s generation to accommodate increasing amounts of utility-scale PV and DG, and the resulting cost of integrating variable renewable resources. The study was jointly funded by the United States Department of Energy and NV Energy, and conducted by a project team comprised of industry experts and research scientists from Navigant Consulting Inc., Sandia National Laboratories, Pacific Northwest National Laboratory and NV Energy.

  9. Large-scale magnetic fields in magnetohydrodynamic turbulence.

    PubMed

    Alexakis, Alexandros

    2013-02-22

    High Reynolds number magnetohydrodynamic turbulence in the presence of zero-flux large-scale magnetic fields is investigated as a function of the magnetic field strength. For a variety of flow configurations, the energy dissipation rate [symbol: see text] follows the scaling [Symbol: see text] proportional U(rms)(3)/ℓ even when the large-scale magnetic field energy is twenty times larger than the kinetic energy. A further increase of the magnetic energy showed a transition to the [Symbol: see text] proportional U(rms)(2) B(rms)/ℓ scaling implying that magnetic shear becomes more efficient at this point at cascading the energy than the velocity fluctuations. Strongly helical configurations form nonturbulent helicity condensates that deviate from these scalings. Weak turbulence scaling was absent from the investigation. Finally, the magnetic energy spectra support the Kolmogorov spectrum k(-5/3) while kinetic energy spectra are closer to the Iroshnikov-Kraichnan spectrum k(-3/2) as observed in the solar wind. PMID:23473153

  10. Fractals and cosmological large-scale structure

    NASA Technical Reports Server (NTRS)

    Luo, Xiaochun; Schramm, David N.

    1992-01-01

    Observations of galaxy-galaxy and cluster-cluster correlations as well as other large-scale structure can be fit with a 'limited' fractal with dimension D of about 1.2. This is not a 'pure' fractal out to the horizon: the distribution shifts from power law to random behavior at some large scale. If the observed patterns and structures are formed through an aggregation growth process, the fractal dimension D can serve as an interesting constraint on the properties of the stochastic motion responsible for limiting the fractal structure. In particular, it is found that the observed fractal should have grown from two-dimensional sheetlike objects such as pancakes, domain walls, or string wakes. This result is generic and does not depend on the details of the growth process.

  11. Condition Monitoring of Large-Scale Facilities

    NASA Technical Reports Server (NTRS)

    Hall, David L.

    1999-01-01

    This document provides a summary of the research conducted for the NASA Ames Research Center under grant NAG2-1182 (Condition-Based Monitoring of Large-Scale Facilities). The information includes copies of view graphs presented at NASA Ames in the final Workshop (held during December of 1998), as well as a copy of a technical report provided to the COTR (Dr. Anne Patterson-Hine) subsequent to the workshop. The material describes the experimental design, collection of data, and analysis results associated with monitoring the health of large-scale facilities. In addition to this material, a copy of the Pennsylvania State University Applied Research Laboratory data fusion visual programming tool kit was also provided to NASA Ames researchers.

  12. Scale Dependence of Magnetic Helicity in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

    2011-01-01

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

  13. SCALE DEPENDENCE OF MAGNETIC HELICITY IN THE SOLAR WIND

    SciTech Connect

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L. E-mail: kandu@iucaa.ernet.in E-mail: melvyn.l.goldstein@nasa.gov

    2011-06-10

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k {approx} 2 AU{sup -1} (or frequency {nu} {approx} 2 {mu}Hz) at distances below 2.8 AU and at k {approx} 30 AU{sup -1} (or {nu} {approx} 25 {mu}Hz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10{sup 45} Mx{sup 2} cycle{sup -1} at large scales and to a three times lower value at smaller scales.

  14. Large-scale polarimetry of large optical galaxies

    NASA Astrophysics Data System (ADS)

    Sholomitskii, G. B.; Maslov, I. A.; Vitrichenko, E. A.

    1999-11-01

    We present preliminary results of wide-field visual CCD polarimetry for large optical galaxies through a concentric multisector radial-tangential polaroid analyzer mounted at the intermediate focus of a Zeiss-1000 telescope. The mean degree of tangential polarization in a 13-arcmin field, which was determined by processing images with imprinted ``orthogonal'' sectors, ranges from several percent (M 82) and 0.51% (the spirals M 51, M 81) to lower values for elliptical galaxies (M 49, M 87). It is emphasized that the parameters of large-scale polarization can be properly determined by using physical models for galaxies; inclination and azimuthal dependences of the degree of polarization are given for spirals.

  15. Scaling laws and coherent structures in the solar wind

    NASA Astrophysics Data System (ADS)

    Bruno, Roberto; D'Amicis, Raffaella; Bavassano, Bruno; Carbone, Vincenzo; Sorriso-Valvo, Luca

    2007-12-01

    The interplanetary medium is characterized by a very high Reynolds number and is pervaded by fluctuations providing information on a wide range of scales, from fractions of second up to the solar rotation period. In the past decade or so, turbulence in the solar wind has been used as a large wind tunnel to investigate scaling laws of turbulent fluctuations and multifractal models. Moreover, new interesting insights in the theory of turbulence have been derived from the point of view which considers a turbulent flow as a complex system, a sort of benchmark for the theory of dynamical systems. Important finding like the lack of a strict self-similarity of the fluctuations with the consequent nonapplicability of strict scale invariance, the strong anisotropy of velocity and magnetic field fluctuations, the clear lack of equipartition between magnetic and kinetic fluctuations all contributed to suggest the idea that interplanetary fluctuations could possibly be due to a mixture of propagating waves and static structures convected by the wind. In this paper we further discuss this point and bring new evidence about the fact that the presence of a background magnetic field introduces not only a symmetry breaking in interplanetary space but also organizes fluctuations about its large scale orientation.

  16. Supporting large-scale computational science

    SciTech Connect

    Musick, R

    1998-10-01

    A study has been carried out to determine the feasibility of using commercial database management systems (DBMSs) to support large-scale computational science. Conventional wisdom in the past has been that DBMSs are too slow for such data. Several events over the past few years have muddied the clarity of this mindset: 1. 2. 3. 4. Several commercial DBMS systems have demonstrated storage and ad-hoc quer access to Terabyte data sets. Several large-scale science teams, such as EOSDIS [NAS91], high energy physics [MM97] and human genome [Kin93] have adopted (or make frequent use of) commercial DBMS systems as the central part of their data management scheme. Several major DBMS vendors have introduced their first object-relational products (ORDBMSs), which have the potential to support large, array-oriented data. In some cases, performance is a moot issue. This is true in particular if the performance of legacy applications is not reduced while new, albeit slow, capabilities are added to the system. The basic assessment is still that DBMSs do not scale to large computational data. However, many of the reasons have changed, and there is an expiration date attached to that prognosis. This document expands on this conclusion, identifies the advantages and disadvantages of various commercial approaches, and describes the studies carried out in exploring this area. The document is meant to be brief, technical and informative, rather than a motivational pitch. The conclusions within are very likely to become outdated within the next 5-7 years, as market forces will have a significant impact on the state of the art in scientific data management over the next decade.

  17. The Cosmology Large Angular Scale Surveyor (CLASS)

    NASA Technical Reports Server (NTRS)

    Harrington, Kathleen; Marriange, Tobias; Aamir, Ali; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Denis, Kevin; Moseley, Samuel H.; Rostem, Karwan; Wollack, Edward

    2016-01-01

    The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).

  18. Numerically modelling the large scale coronal magnetic field

    NASA Astrophysics Data System (ADS)

    Panja, Mayukh; Nandi, Dibyendu

    2016-07-01

    The solar corona spews out vast amounts of magnetized plasma into the heliosphere which has a direct impact on the Earth's magnetosphere. Thus it is important that we develop an understanding of the dynamics of the solar corona. With our present technology it has not been possible to generate 3D magnetic maps of the solar corona; this warrants the use of numerical simulations to study the coronal magnetic field. A very popular method of doing this, is to extrapolate the photospheric magnetic field using NLFF or PFSS codes. However the extrapolations at different time intervals are completely independent of each other and do not capture the temporal evolution of magnetic fields. On the other hand full MHD simulations of the global coronal field, apart from being computationally very expensive would be physically less transparent, owing to the large number of free parameters that are typically used in such codes. This brings us to the Magneto-frictional model which is relatively simpler and computationally more economic. We have developed a Magnetofrictional Model, in 3D spherical polar co-ordinates to study the large scale global coronal field. Here we present studies of changing connectivities between active regions, in response to photospheric motions.

  19. Precision Measurement of Large Scale Structure

    NASA Technical Reports Server (NTRS)

    Hamilton, A. J. S.

    2001-01-01

    The purpose of this grant was to develop and to start to apply new precision methods for measuring the power spectrum and redshift distortions from the anticipated new generation of large redshift surveys. A highlight of work completed during the award period was the application of the new methods developed by the PI to measure the real space power spectrum and redshift distortions of the IRAS PSCz survey, published in January 2000. New features of the measurement include: (1) measurement of power over an unprecedentedly broad range of scales, 4.5 decades in wavenumber, from 0.01 to 300 h/Mpc; (2) at linear scales, not one but three power spectra are measured, the galaxy-galaxy, galaxy-velocity, and velocity-velocity power spectra; (3) at linear scales each of the three power spectra is decorrelated within itself, and disentangled from the other two power spectra (the situation is analogous to disentangling scalar and tensor modes in the Cosmic Microwave Background); and (4) at nonlinear scales the measurement extracts not only the real space power spectrum, but also the full line-of-sight pairwise velocity distribution in redshift space.

  20. Large-scale quasi-geostrophic magnetohydrodynamics

    SciTech Connect

    Balk, Alexander M.

    2014-12-01

    We consider the ideal magnetohydrodynamics (MHD) of a shallow fluid layer on a rapidly rotating planet or star. The presence of a background toroidal magnetic field is assumed, and the 'shallow water' beta-plane approximation is used. We derive a single equation for the slow large length scale dynamics. The range of validity of this equation fits the MHD of the lighter fluid at the top of Earth's outer core. The form of this equation is similar to the quasi-geostrophic (Q-G) equation (for usual ocean or atmosphere), but the parameters are essentially different. Our equation also implies the inverse cascade; but contrary to the usual Q-G situation, the energy cascades to smaller length scales, while the enstrophy cascades to the larger scales. We find the Kolmogorov-type spectrum for the inverse cascade. The spectrum indicates the energy accumulation in larger scales. In addition to the energy and enstrophy, the obtained equation possesses an extra (adiabatic-type) invariant. Its presence implies energy accumulation in the 30° sector around zonal direction. With some special energy input, the extra invariant can lead to the accumulation of energy in zonal magnetic field; this happens if the input of the extra invariant is small, while the energy input is considerable.

  1. Estimation of large-scale dimension densities.

    PubMed

    Raab, C; Kurths, J

    2001-07-01

    We propose a technique to calculate large-scale dimension densities in both higher-dimensional spatio-temporal systems and low-dimensional systems from only a few data points, where known methods usually have an unsatisfactory scaling behavior. This is mainly due to boundary and finite-size effects. With our rather simple method, we normalize boundary effects and get a significant correction of the dimension estimate. This straightforward approach is based on rather general assumptions. So even weak coherent structures obtained from small spatial couplings can be detected with this method, which is impossible by using the Lyapunov-dimension density. We demonstrate the efficiency of our technique for coupled logistic maps, coupled tent maps, the Lorenz attractor, and the Roessler attractor. PMID:11461376

  2. The Cosmology Large Angular Scale Surveyor

    NASA Astrophysics Data System (ADS)

    Marriage, Tobias; Ali, A.; Amiri, M.; Appel, J. W.; Araujo, D.; Bennett, C. L.; Boone, F.; Chan, M.; Cho, H.; Chuss, D. T.; Colazo, F.; Crowe, E.; Denis, K.; Dünner, R.; Eimer, J.; Essinger-Hileman, T.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G. F.; Huang, C.; Irwin, K.; Jones, G.; Karakla, J.; Kogut, A. J.; Larson, D.; Limon, M.; Lowry, L.; Mehrle, N.; Miller, A. D.; Miller, N.; Moseley, S. H.; Novak, G.; Reintsema, C.; Rostem, K.; Stevenson, T.; Towner, D.; U-Yen, K.; Wagner, E.; Watts, D.; Wollack, E.; Xu, Z.; Zeng, L.

    2014-01-01

    Some of the most compelling inflation models predict a background of primordial gravitational waves (PGW) detectable by their imprint of a curl-like "B-mode" pattern in the polarization of the Cosmic Microwave Background (CMB). The Cosmology Large Angular Scale Surveyor (CLASS) is a novel array of telescopes to measure the B-mode signature of the PGW. By targeting the largest angular scales (>2°) with a multifrequency array, novel polarization modulation and detectors optimized for both control of systematics and sensitivity, CLASS sets itself apart in the field of CMB polarization surveys and opens an exciting new discovery space for the PGW and inflation. This poster presents an overview of the CLASS project.

  3. The XMM Large Scale Structure Survey

    NASA Astrophysics Data System (ADS)

    Pierre, Marguerite

    2005-10-01

    We propose to complete, by an additional 5 deg2, the XMM-LSS Survey region overlying the Spitzer/SWIRE field. This field already has CFHTLS and Integral coverage, and will encompass about 10 deg2. The resulting multi-wavelength medium-depth survey, which complements XMM and Chandra deep surveys, will provide a unique view of large-scale structure over a wide range of redshift, and will show active galaxies in the full range of environments. The complete coverage by optical and IR surveys provides high-quality photometric redshifts, so that cosmological results can quickly be extracted. In the spirit of a Legacy survey, we will make the raw X-ray data immediately public. Multi-band catalogues and images will also be made available on short time scales.

  4. Estimation of large-scale dimension densities

    NASA Astrophysics Data System (ADS)

    Raab, Corinna; Kurths, Jürgen

    2001-07-01

    We propose a technique to calculate large-scale dimension densities in both higher-dimensional spatio-temporal systems and low-dimensional systems from only a few data points, where known methods usually have an unsatisfactory scaling behavior. This is mainly due to boundary and finite-size effects. With our rather simple method, we normalize boundary effects and get a significant correction of the dimension estimate. This straightforward approach is based on rather general assumptions. So even weak coherent structures obtained from small spatial couplings can be detected with this method, which is impossible by using the Lyapunov-dimension density. We demonstrate the efficiency of our technique for coupled logistic maps, coupled tent maps, the Lorenz attractor, and the Roessler attractor.

  5. NST: Thermal Modeling for a Large Aperture Solar Telescope

    NASA Astrophysics Data System (ADS)

    Coulter, Roy

    2011-05-01

    Late in the 1990s the Dutch Open Telescope demonstrated that internal seeing in open, large aperture solar telescopes can be controlled by flushing air across the primary mirror and other telescope structures exposed to sunlight. In that system natural wind provides a uniform air temperature throughout the imaging volume, while efficiently sweeping heated air away from the optics and mechanical structure. Big Bear Solar Observatory's New Solar Telescope (NST) was designed to realize that same performance in an enclosed system by using both natural wind through the dome and forced air circulation around the primary mirror to provide the uniform air temperatures required within the telescope volume. The NST is housed in a conventional, ventilated dome with a circular opening, in place of the standard dome slit, that allows sunlight to fall only on an aperture stop and the primary mirror. The primary mirror is housed deep inside a cylindrical cell with only minimal openings in the side at the level of the mirror. To date, the forced air and cooling systems designed for the NST primary mirror have not been implemented, yet the telescope regularly produces solar images indicative of the absence of mirror seeing. Computational Fluid Dynamics (CFD) analysis of the NST primary mirror system along with measurements of air flows within the dome, around the telescope structure, and internal to the mirror cell are used to explain the origin of this seemingly incongruent result. The CFD analysis is also extended to hypothetical systems of various scales. We will discuss the results of these investigations.

  6. Scaling relations for large Martian valleys

    NASA Astrophysics Data System (ADS)

    Som, Sanjoy M.; Montgomery, David R.; Greenberg, Harvey M.

    2009-02-01

    The dendritic morphology of Martian valley networks, particularly in the Noachian highlands, has long been argued to imply a warmer, wetter early Martian climate, but the character and extent of this period remains controversial. We analyzed scaling relations for the 10 large valley systems incised in terrain of various ages, resolvable using the Mars Orbiter Laser Altimeter (MOLA) and the Thermal Emission Imaging System (THEMIS). Four of the valleys originate in point sources with negligible contributions from tributaries, three are very poorly dissected with a few large tributaries separated by long uninterrupted trunks, and three exhibit the dendritic, branching morphology typical of terrestrial channel networks. We generated width-area and slope-area relationships for each because these relations are identified as either theoretically predicted or robust terrestrial empiricisms for graded precipitation-fed, perennial channels. We also generated distance-area relationships (Hack's law) because they similarly represent robust characteristics of terrestrial channels (whether perennial or ephemeral). We find that the studied Martian valleys, even the dendritic ones, do not satisfy those empiricisms. On Mars, the width-area scaling exponent b of -0.7-4.7 contrasts with values of 0.3-0.6 typical of terrestrial channels; the slope-area scaling exponent $\\theta$ ranges from -25.6-5.5, whereas values of 0.3-0.5 are typical on Earth; the length-area, or Hack's exponent n ranges from 0.47 to 19.2, while values of 0.5-0.6 are found on Earth. None of the valleys analyzed satisfy all three relations typical of terrestrial perennial channels. As such, our analysis supports the hypotheses that ephemeral and/or immature channel morphologies provide the closest terrestrial analogs to the dendritic networks on Mars, and point source discharges provide terrestrial analogs best suited to describe the other large Martian valleys.

  7. Design Rules and Scaling for Solar Sails

    NASA Technical Reports Server (NTRS)

    Zeiders, Glenn W.

    2005-01-01

    Useful design rules and simple scaling models have been developed for solar sails. Chief among the conclusions are: 1. Sail distortions contribute to the thrust and moments primarily though the mean squared value of their derivatives (slopes), and the sail behaves like a flat sheet if the value is small. The RMS slope is therefore an important figure of merit, and sail distortion effects on the spacecraft can generally be disregarded if the RMS slope is less than about 10% or so. 2. The characteristic slope of the sail distortion varies inversely with the tension in the sail, and it is the tension that produces the principle loading on the support booms. The tension is not arbitrary, but rather is the value needed to maintain the allowable RMS slope. That corresponds to a halyard force about equal to three times the normal force on the supported sail area. 3. Both the AEC/SRS and L Garde concepts appear to be structurally capable of supporting sail sizes up to a kilometer or more with 1AU solar flux, but select transverse dimensions must be changed to do so. Operational issues such as fabrication, handling, storage and deployment will be the limiting factors.

  8. Solar chromospheric fine scale structures: dynamics and energetics

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.

    2012-01-01

    The solar chromosphere is a very inhomogeneous and dynamic layer of the solar atmosphere that exhibits several phenomena on a wide range of spatial and temporal scales. High-resolution and long-duration observations, employing mostly lines, such as Halpha, the Ca II infrared lines and the Ca II H and K lines, obtained both from ground-based telescope facilities (e.g. DST, VTT, THEMIS, SST, DOT), as well as state-of-the-art satellites (e.g. SOHO, TRACE, HINODE) reveal an incredibly rich, dynamic and highly structured chromospheric environment. What is known in literature as the chromospheric fine-scale structure mainly consists of small fibrilar-like features that connect various parts of quiet/active regions or span across the chromospheric network cell interiors, showing a large diversity of both physical and dynamic characteristics. The highly dynamic, fine-scale chromospheric structures are mostly governed by flows which reflect the complex geometry and dynamics of the local magnetic field and play an important role in the propagation and dissipation of waves. A comprehensive study of these structures requires deep understanding of the physical processes involved and investigation of their intricate link with structures/processes at lower photospheric levels. Furthermore, due to their large number present on the solar surface, it is essential to investigate their impact on the mass and energy transport to higher atmospheric layers through processes such as magnetic reconnection and propagation of waves. The in-depth study of all aforementioned characteristics and processes, with the further addition of non-LTE physics, as well as the use of three-dimensional numerical simulations poses a fascinating challenge for both theory and numerical modeling of chromospheric fine-scale structures.

  9. Scaling studies of solar pumped lasers

    NASA Technical Reports Server (NTRS)

    Christiansen, W. H.; Chang, J.

    1985-01-01

    A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.

  10. Scaling studies of solar pumped lasers

    NASA Astrophysics Data System (ADS)

    Christiansen, W. H.; Chang, J.

    1985-08-01

    A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.

  11. Colloquium: Large scale simulations on GPU clusters

    NASA Astrophysics Data System (ADS)

    Bernaschi, Massimo; Bisson, Mauro; Fatica, Massimiliano

    2015-06-01

    Graphics processing units (GPU) are currently used as a cost-effective platform for computer simulations and big-data processing. Large scale applications require that multiple GPUs work together but the efficiency obtained with cluster of GPUs is, at times, sub-optimal because the GPU features are not exploited at their best. We describe how it is possible to achieve an excellent efficiency for applications in statistical mechanics, particle dynamics and networks analysis by using suitable memory access patterns and mechanisms like CUDA streams, profiling tools, etc. Similar concepts and techniques may be applied also to other problems like the solution of Partial Differential Equations.

  12. Nonthermal Components in the Large Scale Structure

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco

    2004-12-01

    I address the issue of nonthermal processes in the large scale structure of the universe. After reviewing the properties of cosmic shocks and their role as particle accelerators, I discuss the main observational results, from radio to γ-ray and describe the processes that are thought be responsible for the observed nonthermal emissions. Finally, I emphasize the important role of γ-ray astronomy for the progress in the field. Non detections at these photon energies have already allowed us important conclusions. Future observations will tell us more about the physics of the intracluster medium, shocks dissipation and CR acceleration.

  13. Large-scale planar lightwave circuits

    NASA Astrophysics Data System (ADS)

    Bidnyk, Serge; Zhang, Hua; Pearson, Matt; Balakrishnan, Ashok

    2011-01-01

    By leveraging advanced wafer processing and flip-chip bonding techniques, we have succeeded in hybrid integrating a myriad of active optical components, including photodetectors and laser diodes, with our planar lightwave circuit (PLC) platform. We have combined hybrid integration of active components with monolithic integration of other critical functions, such as diffraction gratings, on-chip mirrors, mode-converters, and thermo-optic elements. Further process development has led to the integration of polarization controlling functionality. Most recently, all these technological advancements have been combined to create large-scale planar lightwave circuits that comprise hundreds of optical elements integrated on chips less than a square inch in size.

  14. Neutrinos and large-scale structure

    SciTech Connect

    Eisenstein, Daniel J.

    2015-07-15

    I review the use of cosmological large-scale structure to measure properties of neutrinos and other relic populations of light relativistic particles. With experiments to measure the anisotropies of the cosmic microwave anisotropies and the clustering of matter at low redshift, we now have securely measured a relativistic background with density appropriate to the cosmic neutrino background. Our limits on the mass of the neutrino continue to shrink. Experiments coming in the next decade will greatly improve the available precision on searches for the energy density of novel relativistic backgrounds and the mass of neutrinos.

  15. Large scale phononic metamaterials for seismic isolation

    SciTech Connect

    Aravantinos-Zafiris, N.; Sigalas, M. M.

    2015-08-14

    In this work, we numerically examine structures that could be characterized as large scale phononic metamaterials. These novel structures could have band gaps in the frequency spectrum of seismic waves when their dimensions are chosen appropriately, thus raising the belief that they could be serious candidates for seismic isolation structures. Different and easy to fabricate structures were examined made from construction materials such as concrete and steel. The well-known finite difference time domain method is used in our calculations in order to calculate the band structures of the proposed metamaterials.

  16. Large-scale magnetic fields at high Reynolds numbers in magnetohydrodynamic simulations.

    PubMed

    Hotta, H; Rempel, M; Yokoyama, T

    2016-03-25

    The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (≲10 (12) square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities-that is, large Reynolds numbers. PMID:27013727

  17. Large-scale magnetic fields at high Reynolds numbers in magnetohydrodynamic simulations

    NASA Astrophysics Data System (ADS)

    Hotta, H.; Rempel, M.; Yokoyama, T.

    2016-03-01

    The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (≲1012square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities—that is, large Reynolds numbers.

  18. Large-Scale Organization of Glycosylation Networks

    NASA Astrophysics Data System (ADS)

    Kim, Pan-Jun; Lee, Dong-Yup; Jeong, Hawoong

    2009-03-01

    Glycosylation is a highly complex process to produce a diverse repertoire of cellular glycans that are frequently attached to proteins and lipids. Glycans participate in fundamental biological processes including molecular trafficking and clearance, cell proliferation and apoptosis, developmental biology, immune response, and pathogenesis. N-linked glycans found on proteins are formed by sequential attachments of monosaccharides with the help of a relatively small number of enzymes. Many of these enzymes can accept multiple N-linked glycans as substrates, thus generating a large number of glycan intermediates and their intermingled pathways. Motivated by the quantitative methods developed in complex network research, we investigate the large-scale organization of such N-glycosylation pathways in a mammalian cell. The uncovered results give the experimentally-testable predictions for glycosylation process, and can be applied to the engineering of therapeutic glycoproteins.

  19. Bio-Inspired Wooden Actuators for Large Scale Applications

    PubMed Central

    Rüggeberg, Markus; Burgert, Ingo

    2015-01-01

    Implementing programmable actuation into materials and structures is a major topic in the field of smart materials. In particular the bilayer principle has been employed to develop actuators that respond to various kinds of stimuli. A multitude of small scale applications down to micrometer size have been developed, but up-scaling remains challenging due to either limitations in mechanical stiffness of the material or in the manufacturing processes. Here, we demonstrate the actuation of wooden bilayers in response to changes in relative humidity, making use of the high material stiffness and a good machinability to reach large scale actuation and application. Amplitude and response time of the actuation were measured and can be predicted and controlled by adapting the geometry and the constitution of the bilayers. Field tests in full weathering conditions revealed long-term stability of the actuation. The potential of the concept is shown by a first demonstrator. With the sensor and actuator intrinsically incorporated in the wooden bilayers, the daily change in relative humidity is exploited for an autonomous and solar powered movement of a tracker for solar modules. PMID:25835386

  20. Bio-inspired wooden actuators for large scale applications.

    PubMed

    Rüggeberg, Markus; Burgert, Ingo

    2015-01-01

    Implementing programmable actuation into materials and structures is a major topic in the field of smart materials. In particular the bilayer principle has been employed to develop actuators that respond to various kinds of stimuli. A multitude of small scale applications down to micrometer size have been developed, but up-scaling remains challenging due to either limitations in mechanical stiffness of the material or in the manufacturing processes. Here, we demonstrate the actuation of wooden bilayers in response to changes in relative humidity, making use of the high material stiffness and a good machinability to reach large scale actuation and application. Amplitude and response time of the actuation were measured and can be predicted and controlled by adapting the geometry and the constitution of the bilayers. Field tests in full weathering conditions revealed long-term stability of the actuation. The potential of the concept is shown by a first demonstrator. With the sensor and actuator intrinsically incorporated in the wooden bilayers, the daily change in relative humidity is exploited for an autonomous and solar powered movement of a tracker for solar modules. PMID:25835386

  1. Simultaneous Solar Maximum Mission (SMM) and Very Large Array (VLA) observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Willson, Robert F.

    1991-01-01

    Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun.

  2. ON THE OCCURRENCE OF THE THIRD-ORDER SCALING IN HIGH LATITUDE SOLAR WIND

    SciTech Connect

    Marino, R.; D'Amicis, R.; Bruno, R.; Sorriso-Valvo, L.; Carbone, V.; Veltri, P.

    2012-05-01

    The occurrence and nature of a nonlinear energy cascade within the intermediate scales of solar wind Alfvenic turbulence represents an important open issue. Using in situ measurements of fast, high latitude solar wind taken by the Ulysses spacecraft at solar minima, it is possible to show that a nonlinear energy cascade of imbalanced turbulence is only observed when the solar wind owns peculiar properties. These are the reduction of the local correlation between velocity and magnetic field (weak cross-helicity); the presence of large-scale velocity shears; and the steepening and extension down to low frequencies of the turbulent spectra. Our observations suggest the important role of both large-scale velocity and Alfvenicity of the field fluctuations for the validation of the Yaglom law in solar wind turbulence.

  3. Scaling and Criticality in Large-Scale Neuronal Activity

    NASA Astrophysics Data System (ADS)

    Linkenkaer-Hansen, K.

    The human brain during wakeful rest spontaneously generates large-scale neuronal network oscillations at around 10 and 20 Hz that can be measured non-invasively using magnetoencephalography (MEG) or electroencephalography (EEG). In this chapter, spontaneous oscillations are viewed as the outcome of a self-organizing stochastic process. The aim is to introduce the general prerequisites for stochastic systems to evolve to the critical state and to explain their neurophysiological equivalents. I review the recent evidence that the theory of self-organized criticality (SOC) may provide a unifying explanation for the large variability in amplitude, duration, and recurrence of spontaneous network oscillations, as well as the high susceptibility to perturbations and the long-range power-law temporal correlations in their amplitude envelope.

  4. Local gravity and large-scale structure

    NASA Technical Reports Server (NTRS)

    Juszkiewicz, Roman; Vittorio, Nicola; Wyse, Rosemary F. G.

    1990-01-01

    The magnitude and direction of the observed dipole anisotropy of the galaxy distribution can in principle constrain the amount of large-scale power present in the spectrum of primordial density fluctuations. This paper confronts the data, provided by a recent redshift survey of galaxies detected by the IRAS satellite, with the predictions of two cosmological models with very different levels of large-scale power: the biased Cold Dark Matter dominated model (CDM) and a baryon-dominated model (BDM) with isocurvature initial conditions. Model predictions are investigated for the Local Group peculiar velocity, v(R), induced by mass inhomogeneities distributed out to a given radius, R, for R less than about 10,000 km/s. Several convergence measures for v(R) are developed, which can become powerful cosmological tests when deep enough samples become available. For the present data sets, the CDM and BDM predictions are indistinguishable at the 2 sigma level and both are consistent with observations. A promising discriminant between cosmological models is the misalignment angle between v(R) and the apex of the dipole anisotropy of the microwave background.

  5. Territorial Polymers and Large Scale Genome Organization

    NASA Astrophysics Data System (ADS)

    Grosberg, Alexander

    2012-02-01

    Chromatin fiber in interphase nucleus represents effectively a very long polymer packed in a restricted volume. Although polymer models of chromatin organization were considered, most of them disregard the fact that DNA has to stay not too entangled in order to function properly. One polymer model with no entanglements is the melt of unknotted unconcatenated rings. Extensive simulations indicate that rings in the melt at large length (monomer numbers) N approach the compact state, with gyration radius scaling as N^1/3, suggesting every ring being compact and segregated from the surrounding rings. The segregation is consistent with the known phenomenon of chromosome territories. Surface exponent β (describing the number of contacts between neighboring rings scaling as N^β) appears only slightly below unity, β 0.95. This suggests that the loop factor (probability to meet for two monomers linear distance s apart) should decay as s^-γ, where γ= 2 - β is slightly above one. The later result is consistent with HiC data on real human interphase chromosomes, and does not contradict to the older FISH data. The dynamics of rings in the melt indicates that the motion of one ring remains subdiffusive on the time scale well above the stress relaxation time.

  6. Introducing Large-Scale Innovation in Schools

    NASA Astrophysics Data System (ADS)

    Sotiriou, Sofoklis; Riviou, Katherina; Cherouvis, Stephanos; Chelioti, Eleni; Bogner, Franz X.

    2016-08-01

    Education reform initiatives tend to promise higher effectiveness in classrooms especially when emphasis is given to e-learning and digital resources. Practical changes in classroom realities or school organization, however, are lacking. A major European initiative entitled Open Discovery Space (ODS) examined the challenge of modernizing school education via a large-scale implementation of an open-scale methodology in using technology-supported innovation. The present paper describes this innovation scheme which involved schools and teachers all over Europe, embedded technology-enhanced learning into wider school environments and provided training to teachers. Our implementation scheme consisted of three phases: (1) stimulating interest, (2) incorporating the innovation into school settings and (3) accelerating the implementation of the innovation. The scheme's impact was monitored for a school year using five indicators: leadership and vision building, ICT in the curriculum, development of ICT culture, professional development support, and school resources and infrastructure. Based on about 400 schools, our study produced four results: (1) The growth in digital maturity was substantial, even for previously high scoring schools. This was even more important for indicators such as vision and leadership" and "professional development." (2) The evolution of networking is presented graphically, showing the gradual growth of connections achieved. (3) These communities became core nodes, involving numerous teachers in sharing educational content and experiences: One out of three registered users (36 %) has shared his/her educational resources in at least one community. (4) Satisfaction scores ranged from 76 % (offer of useful support through teacher academies) to 87 % (good environment to exchange best practices). Initiatives such as ODS add substantial value to schools on a large scale.

  7. Introducing Large-Scale Innovation in Schools

    NASA Astrophysics Data System (ADS)

    Sotiriou, Sofoklis; Riviou, Katherina; Cherouvis, Stephanos; Chelioti, Eleni; Bogner, Franz X.

    2016-02-01

    Education reform initiatives tend to promise higher effectiveness in classrooms especially when emphasis is given to e-learning and digital resources. Practical changes in classroom realities or school organization, however, are lacking. A major European initiative entitled Open Discovery Space (ODS) examined the challenge of modernizing school education via a large-scale implementation of an open-scale methodology in using technology-supported innovation. The present paper describes this innovation scheme which involved schools and teachers all over Europe, embedded technology-enhanced learning into wider school environments and provided training to teachers. Our implementation scheme consisted of three phases: (1) stimulating interest, (2) incorporating the innovation into school settings and (3) accelerating the implementation of the innovation. The scheme's impact was monitored for a school year using five indicators: leadership and vision building, ICT in the curriculum, development of ICT culture, professional development support, and school resources and infrastructure. Based on about 400 schools, our study produced four results: (1) The growth in digital maturity was substantial, even for previously high scoring schools. This was even more important for indicators such as vision and leadership" and "professional development." (2) The evolution of networking is presented graphically, showing the gradual growth of connections achieved. (3) These communities became core nodes, involving numerous teachers in sharing educational content and experiences: One out of three registered users (36 %) has shared his/her educational resources in at least one community. (4) Satisfaction scores ranged from 76 % (offer of useful support through teacher academies) to 87 % (good environment to exchange best practices). Initiatives such as ODS add substantial value to schools on a large scale.

  8. 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

  9. Large area Czochralski silicon for solar cells

    NASA Technical Reports Server (NTRS)

    Rea, S. N.; Wakefield, G. F.

    1976-01-01

    A detailed model of a typical Czochralski silicon crystal puller is utilized to predict maximum crystal growth rate as a function of various furnace parameters. Results of this analysis, when combined with multiblade slurry sawing, indicate that the Czochralski process is highly attractive for achieving near-term cost reduction of solar cell silicon.

  10. Investigation of Coronal Large Scale Structures Utilizing Spartan 201 Data

    NASA Technical Reports Server (NTRS)

    Guhathakurta, Madhulika

    1998-01-01

    Two telescopes aboard Spartan 201, a small satellite has been launched from the Space Shuttles, on April 8th, 1993, September 8th, 1994, September 7th, 1995 and November 20th, 1997. The main objective of the mission was to answer some of the most fundamental unanswered questions of solar physics-What accelerates the solar wind and what heats the corona? The two telescopes are 1) Ultraviolet Coronal Spectrometer (UVCS) provided by the Smithsonian Astrophysical Observatory which uses ultraviolet emissions from neutral hydrogen and ions in the corona to determine velocities of the coronal plasma within the solar wind source region, and the temperature and density distributions of protons and 2) White Light Coronagraph (WLC) provided by NASA's Goddard Space Flight Center which measures visible light to determine the density distribution of coronal electrons within the same region. The PI has had the primary responsibility in the development and application of computer codes necessary for scientific data analysis activities, end instrument calibration for the white-light coronagraph for the entire Spartan mission. The PI was responsible for the science output from the WLC instrument. PI has also been involved in the investigation of coronal density distributions in large-scale structures by use of numerical models which are (mathematically) sufficient to reproduce the details of the observed brightness and polarized brightness distributions found in SPARTAN 201 data.