WorldWideScience

Sample records for large-scale tropical circulation

  1. Large scale atmospheric tropical circulation changes and consequences during global warming

    International Nuclear Information System (INIS)

    Gastineau, G.

    2008-01-01

    The changes of the tropical large scale circulation during climate change can have large impacts on human activities. In a first part, the meridional atmospheric tropical circulation was studied in the different coupled models. During climate change, we find, on the one hand, that the Hadley meridional circulation and the subtropical jet are significantly shifted poleward, and on the other hand, that the intensity of the tropical circulation weakens. The slow down of the atmospheric circulation results from the dry static stability changes affecting the tropical troposphere. Secondly, idealized simulations are used to explain the tropical circulation changes. Ensemble simulation using the model LMDZ4 are set up to study the results from the coupled model IPSLCM4. The weakening of the large scale tropical circulation and the poleward shift of the Hadley cells are explained by both the uniform change and the meridional gradient change of the sea surface temperature. Then, we used the atmospheric model LMDZ4 in an aqua-planet configuration. The Hadley circulation changes are explained in a simple framework by the required poleward energy transport. In a last part, we focus on the water vapor distribution and feedback in the climate models. The Hadley circulation changes were shown to have a significant impact on the water vapour feedback during climate change. (author)

  2. RELATIONSHIPS BETWEEN SEA SURFACE TEMPERATURE, LARGE-SCALE ATMOSPHERIC CIRCULATION, AND CONVECTION OVER THE TROPICAL INDIAN AND PACIFIC OCEANS

    Directory of Open Access Journals (Sweden)

    Orbita Roswintiarti

    2008-07-01

    Full Text Available In this paper, the quantitative estimates of the effect of large-scale circulations on the sea surface temperature (SST-tropical convection relationship and the effect of SST on the large-scale circulation-convection relationship over the tropical Indian and Pacific Oceans are presented. Although convection tends to maximize at warm SSTs, increased deep convection is also determined by the divergence (DIV associated with large-scale circulation. An analysis of the relationship between SST and deep convection shows that under subsidence and clear conditions, there is a decrease in convection or increase in Outgoing Longwave Radiation (OLR at a maximum rate of 3.4 Wm-2 °C-1. In the SST range of 25°C to 29.5°C, a large increase in deep convection (decrease in OLR occurs in the tropical Indian and Pacific Oceans. The OLR reduction is found to be a strong function of the large-scale circulation in the Indian and western Pacific Oceans. Under a weak large-scale circulation, the rate of OLR reduction is about    -3.5 Wm-2 °C-1 to -8.1 Wm-2 °C-1. Under the influence of strong rising motions, the rate can increase to about -12.5 Wm-2 °C-1 for the same SST range. The overall relationship between large-scale circulation and deep convection is nearly linear. A maximum rate of OLR reduction with respect to DIV is -6.1 Wm-2 (10-6 s-1 in the western Pacific Ocean. It is also found that the DIV-OLR relationship is less dependent on SST. For example, the rate of OLR reduction over the western Pacific Ocean for 26°C < SST £ 27°C is -4.2 Wm-2 (10-6 s-1, while that for 28°C < SST £ 29°C is  -5.1 Wm-2 (10-6 s-1. These results are expected to have a great importance for climate feedback mechanisms associated with clouds and SST and for climate predictability.

  3. Impact of the intraseasonal variability of large-scale circulation over the Western North Pacific on the characteristics of tropical cyclone track

    OpenAIRE

    Chen, T. C.; Wang, Shih-Yu (Simon); Yen, M. C.; Clark, A. J.

    2009-01-01

    The life cycle of the Southeast Asian–western North Pacific monsoon circulation is established by the northward migrations of the monsoon trough and the western Pacific subtropical anticyclone, and is reflected by the intraseasonal variations of mo nsoon westerlies and trad e easterlies in the form of an east–west seesaw oscillation. In this paper, an effort is made to disclose the influence of this monsoon circulation on tropical cyclone tracks during its different ph ases using composite ch...

  4. Breakdown of large-scale circulation in turbulent rotating convection

    NARCIS (Netherlands)

    Kunnen, R.P.J.; Clercx, H.J.H.; Geurts, Bernardus J.

    2008-01-01

    Turbulent rotating convection in a cylinder is investigated both numerically and experimentally at Rayleigh number Ra = $10^9$ and Prandtl number $\\sigma$ = 6.4. In this Letter we discuss two topics: the breakdown under rotation of the domain-filling large-scale circulation (LSC) typical for

  5. On the response of the tropical atmosphere to large-scale deforestation

    Science.gov (United States)

    Eltahir, E. A. B.; Bras, R. L.

    1993-01-01

    Recent studies on the Amazon deforestation problem predict that removal of the forest will result in a higher surface temperature, a significant reduction in evaporation and precipitation, and possibly significant changes in the tropical circulation. Here, we discuss the basic mechanisms contributing to the response of the tropical atmosphere to deforestation. A simple linear model of the tropical atmosphere is used in studying the effects of deforestation on climate. It is suggested that the impact of large-scale deforestation on the circulation of the tropical atmosphere consists of two components: the response of the tropical circulation to the negative change in precipitation (heating), and the response of the same circulation to the positive change in surface temperature. Owing to their different signs, the changes in predicted temperature and precipitation excite competing responses working in opposite directions. The predicted change in tropical circulation determines the change, if any, in atmospheric moisture convergence, which is equivalent to the change in run-off. The dependence of run-off predictions on the relative magnitudes of the predicted changes in precipitation and surface temperature implies that the predictions about run-off are highly sensitive, which explains, at least partly, the disagreement between the different models concerning the sign of the predicted change in Amazonian run-off.

  6. The Influence of Large-Scale Circulation on Fire Outbreaks in the Amazon Region

    Science.gov (United States)

    Pires, L. B. M.; Romao, M.; Freitas, A. C. V.

    2017-12-01

    The combination of alterations in land use cover and severe droughts may dramatically increase fire outbreaks. Tropical convection in the Amazon Basin is regulated mainly by large-scale atmospheric systems such as the Walker circulation. Many of the documented drought episodes in the Amazon occurred during intense El Niño events such as those recorded in 1926, 1983, 1997-1998, and 2010. However, not all El Niño events are related to drought in the Amazon. Recent studies have also pointed out the importance of the tropical Atlantic Ocean in the modulation of the Amazonian climate, as observed during the drought episodes in 2005 and 2010. This work investigates the fire outbreak tendency in the Amazon region, and the influence of large-scale circulation on these events. Data from the Fire Program of the Center for Weather Forecasting and Climate Studies (CPTEC/INPE) show a substantial increase in the number of fire outbreaks in the last few years, especially during 2016. However, in the 2017 year a sharp drop in fire outbreaks reaching levels similar to the years prior to 2016 is being noted, already showing a reduction of 54% in relation to the preceding 2016 year. The 2015-2016 period was marked by one of the strongest El Niño in history. This was reflected in the increase of the number of fire outbreaks due to the increase of the drought and temperature elevation period. On the other hand, the 2017 year is being characterized by a condition of neutrality in relation to the El Niño-Southern Oscillation (ENSO) phenomena, and have overall presented positive sea surface temperature (SST) anomalies in the tropical Atlantic. Variations of these systems and their relation to fire outbreaks is demonstrated.

  7. The influence of Seychelles Dome on the large scale Tropical Variability

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    Manola, Iris; Selten, Frank; Hazeleger, Wilco

    2013-04-01

    The Seychelles Dome (SD) is the thermocline ridge just South of the equator in the Western Indian Ocean basin. It is characterized by strong atmospheric convection and a shallow thermocline and is associated with large intraseasonal convection and SST variability (Harrison and Vecchi 2001). The SD is influenced by surface and subsurface processes, such as air-sea fluxes, Ekman upwelling from wind stress curl, ocean dynamics (vertical mixing) and oceanic Rossby waves from southeastern Indian Ocean. The favoring season for a strong SD is the boreal winter, where the thermocline is most shallow. Then the southeasterly trade winds converge with the northwesterly monsoonal winds over the intertropical convergence zone and cause cyclonic wind stress curl that drives Ekman divergence and a ridging of the thermocline. It is found that the subseasonal and interranual variability of the SD is influenced by large scale events, such as the Indian Ocean Dipole (IOD), the ENSO and the Madden-Julian Oscillation (MJO) (Tozuka et al., 2010, Lloyd and Vecchi, 2010). The SD is enhanced by cooling events in the Western Indian Ocean and easterly winds that raise the thermocline and increase the upwelling. This can be associated with a strong Walker circulation, like negative IOD conditions or La Nina-like conditions. So far the studies focus on the origins of the SD variability, but the influence of the SD itself on regional or large scale climate is largely unknown. In this study we focus on the influence of the SD variations on the large scale tropical circulation. We analyze the covariance of the SD variations and the tropical circulation in a 200 year control imulation of the climate model EC-EARTH and perform idealized SST forced simulations to study the character of the atmospheric response and its relation to ENSO, IOD and MJO. References -Harrison, D. E. and G. A. Vecchi, 2001: January 1999 Indian Ocean cooling event. Geophys. Res. Lett., 28, 3717-3720. -Lloyd, I. D., and G. A

  8. Prediction of monthly rainfall on homogeneous monsoon regions of India based on large scale circulation patterns using Genetic Programming

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    Kashid, Satishkumar S.; Maity, Rajib

    2012-08-01

    SummaryPrediction of Indian Summer Monsoon Rainfall (ISMR) is of vital importance for Indian economy, and it has been remained a great challenge for hydro-meteorologists due to inherent complexities in the climatic systems. The Large-scale atmospheric circulation patterns from tropical Pacific Ocean (ENSO) and those from tropical Indian Ocean (EQUINOO) are established to influence the Indian Summer Monsoon Rainfall. The information of these two large scale atmospheric circulation patterns in terms of their indices is used to model the complex relationship between Indian Summer Monsoon Rainfall and the ENSO as well as EQUINOO indices. However, extracting the signal from such large-scale indices for modeling such complex systems is significantly difficult. Rainfall predictions have been done for 'All India' as one unit, as well as for five 'homogeneous monsoon regions of India', defined by Indian Institute of Tropical Meteorology. Recent 'Artificial Intelligence' tool 'Genetic Programming' (GP) has been employed for modeling such problem. The Genetic Programming approach is found to capture the complex relationship between the monthly Indian Summer Monsoon Rainfall and large scale atmospheric circulation pattern indices - ENSO and EQUINOO. Research findings of this study indicate that GP-derived monthly rainfall forecasting models, that use large-scale atmospheric circulation information are successful in prediction of All India Summer Monsoon Rainfall with correlation coefficient as good as 0.866, which may appears attractive for such a complex system. A separate analysis is carried out for All India Summer Monsoon rainfall for India as one unit, and five homogeneous monsoon regions, based on ENSO and EQUINOO indices of months of March, April and May only, performed at end of month of May. In this case, All India Summer Monsoon Rainfall could be predicted with 0.70 as correlation coefficient with somewhat lesser Correlation Coefficient (C.C.) values for different

  9. Forced synchronization of large-scale circulation to increase predictability of surface states

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    Shen, Mao-Lin; Keenlyside, Noel; Selten, Frank; Wiegerinck, Wim; Duane, Gregory

    2016-04-01

    Numerical models are key tools in the projection of the future climate change. The lack of perfect initial condition and perfect knowledge of the laws of physics, as well as inherent chaotic behavior limit predictions. Conceptually, the atmospheric variables can be decomposed into a predictable component (signal) and an unpredictable component (noise). In ensemble prediction the anomaly of ensemble mean is regarded as the signal and the ensemble spread the noise. Naturally the prediction skill will be higher if the signal-to-noise ratio (SNR) is larger in the initial conditions. We run two ensemble experiments in order to explore a way to reduce the SNR of surface winds and temperature. One ensemble experiment is AGCM with prescribing sea surface temperature (SST); the other is AGCM with both prescribing SST and nudging the high-level temperature and winds to ERA-Interim. Each ensemble has 30 members. Larger SNR is expected and found over the tropical ocean in the first experiment because the tropical circulation is associated with the convection and the associated surface wind convergence as these are to a large extent driven by the SST. However, small SNR is found over high latitude ocean and land surface due to the chaotic and non-synchronized atmosphere states. In the second experiment the higher level temperature and winds are forced to be synchronized (nudged to reanalysis) and hence a larger SNR of surface winds and temperature is expected. Furthermore, different nudging coefficients are also tested in order to understand the limitation of both synchronization of large-scale circulation and the surface states. These experiments will be useful for the developing strategies to synchronize the 3-D states of atmospheric models that can be later used to build a super model.

  10. Large-Scale Ocean Circulation-Cloud Interactions Reduce the Pace of Transient Climate Change

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    Trossman, D. S.; Palter, J. B.; Merlis, T. M.; Huang, Y.; Xia, Y.

    2016-01-01

    Changes to the large scale oceanic circulation are thought to slow the pace of transient climate change due, in part, to their influence on radiative feedbacks. Here we evaluate the interactions between CO2-forced perturbations to the large-scale ocean circulation and the radiative cloud feedback in a climate model. Both the change of the ocean circulation and the radiative cloud feedback strongly influence the magnitude and spatial pattern of surface and ocean warming. Changes in the ocean circulation reduce the amount of transient global warming caused by the radiative cloud feedback by helping to maintain low cloud coverage in the face of global warming. The radiative cloud feedback is key in affecting atmospheric meridional heat transport changes and is the dominant radiative feedback mechanism that responds to ocean circulation change. Uncertainty in the simulated ocean circulation changes due to CO2 forcing may contribute a large share of the spread in the radiative cloud feedback among climate models.

  11. Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

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    Nuijens, Louise; Emanuel, Kerry; Masunaga, Hirohiko; L'Ecuyer, Tristan

    2017-11-01

    Space-borne observations reveal that 20-40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column radiative-convective model of hydrostatic, nonlinear flow on a non-rotating sphere, with parameterized convection and radiation, and review ongoing efforts in high-resolution modeling and observations of warm rain. The model experiments investigate the response of convection and circulation to sea surface temperature (SST) gradients between the columns and to changes in a parameter that controls the conversion of cloud condensate to rain. Convection over the cold ocean collapses to a shallow mode with tops near 850 hPa, but a congestus mode with tops near 600 hPa can develop at small SST differences when warm rain formation is more efficient. Here, interactive radiation and the response of the circulation are crucial: along with congestus a deeper moist layer develops, which leads to less low-level radiative cooling, a smaller buoyancy gradient between the columns, and therefore a weaker circulation and less subsidence over the cold ocean. The congestus mode is accompanied with more surface precipitation in the subsiding column and less surface precipitation in the deep convecting column. For the shallow mode over colder oceans, circulations also weaken with more efficient warm rain formation, but only marginally. Here, more warm rain reduces convective tops and the boundary layer depth—similar to Large-Eddy Simulation (LES) studies—which reduces the integrated buoyancy gradient. Elucidating the impact of warm rain can benefit from large-domain high-resolution simulations and observations. Parameterizations of warm rain may be constrained through collocated cloud and rain profiling from ground, and concurrent changes in convection and rain in subsiding and convecting branches of

  12. Large-scale circulation departures related to wet episodes in north-east Brazil

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    Sikdar, Dhirendra N.; Elsner, James B.

    1987-01-01

    Large scale circulation features are presented as related to wet spells over northeast Brazil (Nordeste) during the rainy season (March and April) of 1979. The rainy season is divided into dry and wet periods; the FGGE and geostationary satellite data was averaged; and mean and departure fields of basic variables and cloudiness were studied. Analysis of seasonal mean circulation features show: lowest sea level easterlies beneath upper level westerlies; weak meridional winds; high relative humidity over the Amazon basin and relatively dry conditions over the South Atlantic Ocean. A fluctuation was found in the large scale circulation features on time scales of a few weeks or so over Nordeste and the South Atlantic sector. Even the subtropical High SLPs have large departures during wet episodes, implying a short period oscillation in the Southern Hemisphere Hadley circulation.

  13. Large-scale circulation departures related to wet episodes in northeast Brazil

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    Sikdar, D. N.; Elsner, J. B.

    1985-01-01

    Large scale circulation features are presented as related to wet spells over northeast Brazil (Nordeste) during the rainy season (March and April) of 1979. The rainy season season is devided into dry and wet periods, the FGGE and geostationary satellite data was averaged and mean and departure fields of basic variables and cloudiness were studied. Analysis of seasonal mean circulation features show: lowest sea level easterlies beneath upper level westerlies; weak meridional winds; high relative humidity over the Amazon basin and relatively dry conditions over the South Atlantic Ocean. A fluctuation was found in the large scale circulation features on time scales of a few weeks or so over Nordeste and the South Atlantic sector. Even the subtropical High SLP's have large departures during wet episodes, implying a short period oscillation in the Southern Hemisphere Hadley circulation.

  14. Effect of plumes on measuring the large scale circulation in turbulent Rayleigh-Bénard convection

    NARCIS (Netherlands)

    Stevens, Richard Johannes Antonius Maria; Clercx, H.J.H.; Lohse, Detlef

    2011-01-01

    We studied the properties of the large-scale circulation (LSC) in turbulent Rayleigh-Bénard (RB) convection by using results from direct numerical simulations in which we placed a large number of numerical probes close to the sidewall. The LSC orientation is determined by either a cosine or a

  15. The Hamburg large scale geostrophic ocean general circulation model. Cycle 1

    International Nuclear Information System (INIS)

    Maier-Reimer, E.; Mikolajewicz, U.

    1992-02-01

    The rationale for the Large Scale Geostrophic ocean circulation model (LSG-OGCM) is based on the observations that for a large scale ocean circulation model designed for climate studies, the relevant characteristic spatial scales are large compared with the internal Rossby radius throughout most of the ocean, while the characteristic time scales are large compared with the periods of gravity modes and barotropic Rossby wave modes. In the present version of the model, the fast modes have been filtered out by a conventional technique of integrating the full primitive equations, including all terms except the nonlinear advection of momentum, by an implicit time integration method. The free surface is also treated prognostically, without invoking a rigid lid approximation. The numerical scheme is unconditionally stable and has the additional advantage that it can be applied uniformly to the entire globe, including the equatorial and coastal current regions. (orig.)

  16. Response of deep and shallow tropical maritime cumuli to large-scale processes

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    Yanai, M.; Chu, J.-H.; Stark, T. E.; Nitta, T.

    1976-01-01

    The bulk diagnostic method of Yanai et al. (1973) and a simplified version of the spectral diagnostic method of Nitta (1975) are used for a more quantitative evaluation of the response of various types of cumuliform clouds to large-scale processes, using the same data set in the Marshall Islands area for a 100-day period in 1956. The dependence of the cloud mass flux distribution on radiative cooling, large-scale vertical motion, and evaporation from the sea is examined. It is shown that typical radiative cooling rates in the tropics tend to produce a bimodal distribution of mass spectrum exhibiting deep and shallow clouds. The bimodal distribution is further enhanced when the large-scale vertical motion is upward, and a nearly unimodal distribution of shallow clouds prevails when the relative cooling is compensated by the heating due to the large-scale subsidence. Both deep and shallow clouds are modulated by large-scale disturbances. The primary role of surface evaporation is to maintain the moisture flux at the cloud base.

  17. Extreme Temperature Regimes during the Cool Season and their Associated Large-Scale Circulations

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    Xie, Z.

    2015-12-01

    In the cool season (November-March), extreme temperature events (ETEs) always hit the continental United States (US) and provide significant societal impacts. According to the anomalous amplitudes of the surface air temperature (SAT), there are two typical types of ETEs, e.g. cold waves (CWs) and warm waves (WWs). This study used cluster analysis to categorize both CWs and WWs into four distinct regimes respectively and investigated their associated large-scale circulations on intra-seasonal time scale. Most of the CW regimes have large areal impact over the continental US. However, the distribution of cold SAT anomalies varies apparently in four regimes. In the sea level, the four CW regimes are characterized by anomalous high pressure over North America (near and to west of cold anomaly) with different extension and orientation. As a result, anomalous northerlies along east flank of anomalous high pressure convey cold air into the continental US. To the middle troposphere, the leading two groups feature large-scale and zonally-elongated circulation anomaly pattern, while the other two regimes exhibit synoptic wavetrain pattern with meridionally elongated features. As for the WW regimes, there are some patterns symmetry and anti-symmetry with respect to CW regimes. The WW regimes are characterized by anomalous low pressure and southerlies wind over North America. The first and fourth groups are affected by remote forcing emanating from North Pacific, while the others appear mainly locally forced.

  18. Dominant Large-Scale Atmospheric Circulation Systems for the Extreme Precipitation over the Western Sichuan Basin in Summer 2013

    Directory of Open Access Journals (Sweden)

    Yamin Hu

    2015-01-01

    Full Text Available The western Sichuan Basin (WSB is a rainstorm center influenced by complicated factors such as topography and circulation. Based on multivariable empirical orthogonal function technique for extreme precipitation processes (EPP in WSB in 2013, this study reveals the dominant circulation patterns. Results indicate that the leading modes are characterized by “Saddle” and “Sandwich” structures, respectively. In one mode, a TC from the South China Sea (SCS converts into the inverted trough and steers warm moist airflow northward into the WSB. At the same time, WPSH extends westward over the Yangtze River and conveys a southeasterly warm humid flow. In the other case, WPSH is pushed westward by TC in the Western Pacific and then merges with an anomalous anticyclone over SCS. The anomalous anticyclone and WPSH form a conjunction belt and convey the warm moist southwesterly airflow to meet with the cold flow over the WSB. The configurations of WPSH and TC in the tropic and the blocking and trough in the midhigh latitudes play important roles during the EPPs over the WSB. The persistence of EPPs depends on the long-lived large-scale circulation configuration steady over the suitable positions.

  19. Meridional overturning and large-scale circulation of the Indian Ocean

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    Ganachaud, Alexandre; Wunsch, Carl; Marotzke, Jochem; Toole, John

    2000-11-01

    The large scale Indian Ocean circulation is estimated from a global hydrographic inverse geostrophic box model with a focus on the meridional overturning circulation (MOC). The global model is based on selected recent World Ocean Circulation Experiment (WOCE) sections which in the Indian Basin consist of zonal sections at 32°S, 20°S and 8°S, and a section between Bali and Australia from the Java-Australia Dynamic Experiment (JADE). The circulation is required to conserve mass, salinity, heat, silica and "PO" (170PO4+O2). Near-conservation is imposed within layers bounded by neutral surfaces, while permitting advective and diffusive exchanges between the layers. Conceptually, the derived circulation is an estimate of the average circulation for the period 1987-1995. A deep inflow into the Indian Basin of 11±4 Sv is found, which is in the lower range of previous estimates, but consistent with conservation requirements and the global data set. The Indonesian Throughflow (ITF) is estimated at 15±5 Sv. The flow in the Mozambique Channel is of the same magnitude, implying a weak net flow between Madagascar and Australia. A net evaporation of -0.6±0.4 Sv is found between 32°S and 8°S, consistent with independent estimates. No net heat gain is found over the Indian Basin (0.1 ± 0.2PW north of 32°S) as a consequence of the large warm water influx from the ITF. Through the use of anomaly equations, the average dianeutral upwelling and diffusion between the sections are required and resolved, with values in the range 1-3×10-5 cm s-1 for the upwelling and 2-10 cm2 s-1 for the diffusivity.

  20. Diversity in the representation of large-scale circulation associated with ENSO-Indian summer monsoon teleconnections in CMIP5 models

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    Ramu, Dandi A.; Chowdary, Jasti S.; Ramakrishna, S. S. V. S.; Kumar, O. S. R. U. B.

    2018-04-01

    Realistic simulation of large-scale circulation patterns associated with El Niño-Southern Oscillation (ENSO) is vital in coupled models in order to represent teleconnections to different regions of globe. The diversity in representing large-scale circulation patterns associated with ENSO-Indian summer monsoon (ISM) teleconnections in 23 Coupled Model Intercomparison Project Phase 5 (CMIP5) models is examined. CMIP5 models have been classified into three groups based on the correlation between Niño3.4 sea surface temperature (SST) index and ISM rainfall anomalies, models in group 1 (G1) overestimated El Niño-ISM teleconections and group 3 (G3) models underestimated it, whereas these teleconnections are better represented in group 2 (G2) models. Results show that in G1 models, El Niño-induced Tropical Indian Ocean (TIO) SST anomalies are not well represented. Anomalous low-level anticyclonic circulation anomalies over the southeastern TIO and western subtropical northwest Pacific (WSNP) cyclonic circulation are shifted too far west to 60° E and 120° E, respectively. This bias in circulation patterns implies dry wind advection from extratropics/midlatitudes to Indian subcontinent. In addition to this, large-scale upper level convergence together with lower level divergence over ISM region corresponding to El Niño are stronger in G1 models than in observations. Thus, unrealistic shift in low-level circulation centers corroborated by upper level circulation changes are responsible for overestimation of ENSO-ISM teleconnections in G1 models. Warm Pacific SST anomalies associated with El Niño are shifted too far west in many G3 models unlike in the observations. Further large-scale circulation anomalies over the Pacific and ISM region are misrepresented during El Niño years in G3 models. Too strong upper-level convergence away from Indian subcontinent and too weak WSNP cyclonic circulation are prominent in most of G3 models in which ENSO-ISM teleconnections are

  1. The impact of large-scale circulation patterns on summer crop yields in IP

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    Capa Morocho, Mirian; Rodríguez Fonseca, Belén; Ruiz Ramos, Margarita

    2014-05-01

    Large-scale circulations patterns (ENSO, NAO) have been shown to have a significant impact on seasonal weather, and therefore on crop yield over many parts of the world(Garnett and Khandekar, 1992; Aasa et al., 2004; Rozas and Garcia-Gonzalez, 2012). In this study, we analyze the influence of large-scale circulation patterns and regional climate on the principal components of maize yield variability in Iberian Peninsula (IP) using reanalysis datasets. Additionally, we investigate the modulation of these relationships by multidecadal patterns. This study is performed analyzing long time series of maize yield, only climate dependent, computed with the crop model CERES-maize (Jones and Kiniry, 1986) included in Decision Support System for Agrotechnology Transfer (DSSAT v.4.5). To simulate yields, reanalysis daily data of radiation, maximum and minimum temperature and precipitation were used. The reanalysis climate data were obtained from National Center for Environmental Prediction (20th Century and NCEP) and European Centre for Medium-Range Weather Forecasts (ECMWF) data server (ERA 40 and ERA Interim). Simulations were run at five locations: Lugo (northwestern), Lerida (NE), Madrid (central), Albacete (southeastern) and Córdoba (S IP) (Gabaldón et al., 2013). From these time series standardized anomalies were calculated. Afterwards, time series were time filtered to focus on the interannual-to-multiannual variability, splitting up in two components: low frequency (LF) and high frequency (HF) time scales. The principal components of HF yield anomalies in IP were compared with a set of documented patterns. These relationships were compared with multidecadal patterns, as Atlanctic Multidecadal Oscillations (AMO) and Interdecadal Pacific Oscillations (IPO). The results of this study have important implications in crop forecasting. In this way, it may have a positive impact on both public (agricultural planning) and private (decision support to farmers, insurance

  2. Cessations and reversals of the large-scale circulation in turbulent thermal convection.

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    Xi, Heng-Dong; Xia, Ke-Qing

    2007-06-01

    We present an experimental study of cessations and reversals of the large-scale circulation (LSC) in turbulent thermal convection in a cylindrical cell of aspect ratio (Gamma) 1/2 . It is found that cessations and reversals of the LSC occur in Gamma = 1/2 geometry an order-of-magnitude more frequently than they do in Gamma=1 cells, and that after a cessation the LSC is most likely to restart in the opposite direction, i.e., reversals of the LSC are the most probable cessation events. This contrasts sharply to the finding in Gamma=1 geometry and implies that cessations in the two geometries are governed by different dynamics. It is found that the occurrence of reversals is a Poisson process and that a stronger rebound of the flow strength after a reversal or cessation leads to a longer period of stability of the LSC. Several properties of reversals and cessations in this system are found to be statistically similar to those of geomagnetic reversals. A direct measurement of the velocity field reveals that a cessation corresponds to a momentary decoherence of the LSC.

  3. Extreme hydrometeorological events in the Peruvian Central Andes during austral summer and their relationship with the large-scale circulation

    Science.gov (United States)

    Sulca, Juan C.

    In this Master's dissertation, atmospheric circulation patterns associated with extreme hydrometeorological events in the Mantaro Basin, Peruvian Central Andes, and their teleconnections during the austral summer (December-January-February-March) are addressed. Extreme rainfall events in the Mantaro basin are related to variations of the large-scale circulation as indicated by the changing strength of the Bolivian High-Nordeste Low (BH-NL) system. Dry (wet) spells are associated with a weakening (strengthening) of the BH-NL system and reduced (enhanced) influx of moist air from the lowlands to the east due to strengthened westerly (easterly) wind anomalies at mid- and upper-tropospheric levels. At the same time extreme rainfall events of the opposite sign occur over northeastern Brazil (NEB) due to enhanced (inhibited) convective activity in conjunction with a strengthened (weakened) Nordeste Low. Cold episodes in the Mantaro Basin are grouped in three types: weak, strong and extraordinary cold episodes. Weak and strong cold episodes in the MB are mainly associated with a weakening of the BH-NL system due to tropical-extratropical interactions. Both types of cold episodes are associated with westerly wind anomalies at mid- and upper-tropospheric levels aloft the Peruvian Central Andes, which inhibit the influx of humid air masses from the lowlands to the east and hence limit the potential for development of convective cloud cover. The resulting clear sky conditions cause nighttime temperatures to drop, leading to cold extremes below the 10-percentile. Extraordinary cold episodes in the MB are associated with cold and dry polar air advection at all tropospheric levels toward the central Peruvian Andes. Therefore, weak and strong cold episodes in the MB appear to be caused by radiative cooling associated with reduced cloudiness, rather than cold air advection, while the latter plays an important role for extraordinary cold episodes only.

  4. Large-Scale Influences on the Genesis of Tropical Cyclone Karl (2010)

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    Griffin, K.; Bosart, L. F.

    2012-12-01

    The events leading up to the genesis of Tropical Cyclone (TC) Karl (2010) provides a unique opportunity to examine the continuing problem of understanding tropical cyclogenesis. The PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT) field campaign allowed for detailed investigation of the tropical disturbance that served as the precursor to TC Karl as it progressed westward through the Caribbean Sea. The purpose of this presentation is to examine the evolution of the pre-Karl disturbance using both common synoptic-scale analyses as well as statistically-based equatorial wave analyses, focusing on where these analyses complement and enhance each other. One of the major factors in the initial spin-up of the pre-Karl tropical disturbance is a surge of southerly and westerly winds from northern South America on 8-10 September 2010. As the surge entered the Caribbean on 9 September, it aided in the formation of a nearly closed earth-relative cyclonic circulation near the southern Leeward Islands. This circulation weakened late on 10 September and remained weak through 13 September before increased organization led to TC genesis on 14 September. This southerly wind surge can be traced to a well-defined surge of anomalously cold air and enhanced southerly winds originating in the lee of the Argentinian Andes over a week prior. While the temperature anomalies wash out prior to reaching the equator, anomalous low-level winds progress into Colombia and Venezuela, where topography aids in turning the southerly winds eastward. An investigation of the pre-Karl environment utilizing wavenumber-frequency filtering techniques also suggests that the initial spin-up of pre-Karl can be associated with the active phase of a convectively coupled Kelvin wave (CCKW). The observed formation of the nearly closed cyclonic circulation on 10 September is well timed with the passage of anomalous westerly winds along and behind the convectively active phase of a CCKW. These

  5. The relationship between large-scale and convective states in the tropics - Towards an improved representation of convection in large-scale models

    Energy Technology Data Exchange (ETDEWEB)

    Jakob, Christian [Monash Univ., Melbourne, VIC (Australia)

    2015-02-26

    This report summarises an investigation into the relationship of tropical thunderstorms to the atmospheric conditions they are embedded in. The study is based on the use of radar observations at the Atmospheric Radiation Measurement site in Darwin run under the auspices of the DOE Atmospheric Systems Research program. Linking the larger scales of the atmosphere with the smaller scales of thunderstorms is crucial for the development of the representation of thunderstorms in weather and climate models, which is carried out by a process termed parametrisation. Through the analysis of radar and wind profiler observations the project made several fundamental discoveries about tropical storms and quantified the relationship of the occurrence and intensity of these storms to the large-scale atmosphere. We were able to show that the rainfall averaged over an area the size of a typical climate model grid-box is largely controlled by the number of storms in the area, and less so by the storm intensity. This allows us to completely rethink the way we represent such storms in climate models. We also found that storms occur in three distinct categories based on their depth and that the transition between these categories is strongly related to the larger scale dynamical features of the atmosphere more so than its thermodynamic state. Finally, we used our observational findings to test and refine a new approach to cumulus parametrisation which relies on the stochastic modelling of the area covered by different convective cloud types.

  6. Simulating the impact of the large-scale circulation on the 2-m temperature and precipitation climatology

    Science.gov (United States)

    The impact of the simulated large-scale atmospheric circulation on the regional climate is examined using the Weather Research and Forecasting (WRF) model as a regional climate model. The purpose is to understand the potential need for interior grid nudging for dynamical downscal...

  7. Various approaches to the modelling of large scale 3-dimensional circulation in the Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shaji, C.; Bahulayan, N.; Rao, A.D.; Dube, S.K.

    In this paper, the three different approaches to the modelling of large scale 3-dimensional flow in the ocean such as the diagnostic, semi-diagnostic (adaptation) and the prognostic are discussed in detail. Three-dimensional solutions are obtained...

  8. Interannual Variability of the Meridional Width of the Baiu Rainband in June and the Associated Large-Scale Atmospheric Circulations

    Science.gov (United States)

    Tsuji, K.; Tomita, T.

    2016-12-01

    Baiu front, which is defined as a boundary between tropical and polar air masses in the East Asia-western North Pacific sector in boreal early summer, slowly migrates northward with the daily meridional swings. Thus, the interannual variability of meridional width of the baiu rainband reflects the slow northward migration and the daily meridional swings of the baiu front. This study focuses on the meridional width of baiu rainband only in June when the baiu front extends on Japan, and investigates how the width is related to the rainfall of Japan with discussions of associated anomalous large-scale atmospheric circulations. The meridional width of baiu rainband is defined based on the monthly-mean precipitation rate of June, whose threshold is 5mm day-1 that is averaged in 130°-150°E. There is a significant positive correlation between the variations of southern and northern edges of the baiu rainband in June. However, the interannual variance of the southern edge is almost twice larger than that of the northern one. That is, the interannual variability of the meridional width is chiefly caused by the variations of southern edge, and the contribution of northern ones is small. When the meridonal width is narrow (wide), an anomalous anticyclonic (cyclonic) circulation appears to the south of Japan, and the precipitation rate increases (decreases) in the western part of Japan while decreases (increases) in the counterpart. In other words, a local dipole with a node at 140°E appears around Japan in the baiu rainfall anomalies. The anomalous anticyclonic (cyclonic) circulation to the south of Japan, which controls the interannual variability of meridional width of the baiu rainband, is induced by the strength of Indian summer monsoon. When the convective activity of Indian summer monsoon is strong (week), the Tibetan high in the upper troposphere extends more (less) eastward. The induced stronger (weaker) descent leads stronger (weaker) Bonin high in the western

  9. Nutrient Uptake and Metabolism Along a Large Scale Tropical Physical-Chemical Gradient

    Science.gov (United States)

    Tromboni, F.; Neres-Lima, V.; Saltarelli, W. A.; Miwa, A. C. P.; Cunha, D. G. F.

    2016-12-01

    Nutrient spiraling is a whole-system approach for estimating nutrient uptake that can be used to assess aquatic ecosystems' responses to environmental change and anthropogenic impacts. Historically research on nutrient dynamic uptake in streams has focused on single nutrient dynamics and only rarely the stoichiometric uptake has been considered and linked to carbon metabolism driven by autotrophic and heterotrophic production. We investigated the relationship between uptake of phosphate (PO43-), nitrate (NO3-) ammonium (NH4+) and total dissolve nitrogen (DIN)/ PO43-; and gross primary production (GPP), respiration (R), and net ecosystem productivity (NEP) in six relatively pristine streams with differences regarding canopy cover and physical characteristics, located in a large scale gradient from tropical Atlantic Forest to an Atlantic forest/Cerrado (Brazilian Savanna) transition. We carried out whole stream instantaneous additions of PO43-, NO3- and NH4+ added to each stream in combination, using the TASCC (Tracer Additions for Spiraling Curve Characterization) method. Metabolism measurements were performed in the same streams right after uptake was measured, using one-station open channel method and re-aeration estimations for those sites. We found different background concentrations in the streams located in the Atlantic forest compared with the transition area with Cerrado. In general PO43- and NO3- uptake increased with the decreasing of canopy cover, while a positive relation with background concentration better explained NH4+uptake. DIN/PO43- uptake increased with increasing R and NEP. Little work on functional characteristics of pristine streams has been conducted in this region and this work provides an initial characterization on nitrogen and phosphorus dynamics as well as their stoichiometric uptake in streams.

  10. Interannual Variability in the Position and Strength of the East Asian Jet Stream and Its Relation to Large - scale Circulation

    Science.gov (United States)

    Chan, Duo; Zhang, Yang; Wu, Qigang

    2013-04-01

    East Asian Jet Stream (EASJ) is charactered by obvious interannual variability in strength and position (latitude), with wide impacts on East Asian climate in all seasons. In this study, two indices are established to measure the interannual variability in intensity and position of EAJS. Possible causing factors, including both local signals and non-local large-scale circulation, are examined using NCAP-NCAR reanalysis data to investigate their relations with jet variation. Our analysis shows that the relationship between the interannual variations of EASJ and these factors depends on seasons. In the summer, both the intensity and position of EASJ are closely related to the meridional gradient of local surface temperature, but display no apparent relationship with the larg-scale circulation. In cold seasons (autumn, winter and spring), both the local factor and the large-scale circulation, i.e. the Pacific/North American teleconnection pattern (PNA), play important roles in the interannual variability of the jet intensity. The variability in the jet position, however, is more correlated to the Arctic Oscillation (AO), especially in winter. Diagnostic analysis indicates that transient eddy activity plays an important role in connecting the interannual variability of EASJ position with AO.

  11. Dynamics of large scale 3-dimensional circulation of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Swapna, P.

    -diagnostic and prognostic modes. Such a model could identify both the local and remote forcing of the Indian Ocean circulation. The other objectives of the thesis are the following: (i) To study the steady state 3-dimensional circulation of Indian Ocean based on semi...

  12. Large scale circulation in the convection zone and solar differential rotation

    Energy Technology Data Exchange (ETDEWEB)

    Belvedere, G [Instituto di Astronomia dell' Universita di Catania, 95125 Italy; Paterno, L [Osservatorio Astrofisico di Catania, 95125 Italy

    1976-04-01

    In this paper the dependence on depth and latitude of the solar angular velocity produced by a meridian circulation in the convection zone is studied assuming that the main mechanism responsible for setting up and driving the circulation is the interaction of rotation with convection. The first order equations (perturbation of the spherically symmetric state are solved in the Boussinesq approximation and in the steady state for the axissymmetric case. The interaction of convection with rotation is modelled by a convective transport coefficient. The model is consistent with the fact that the interaction of convection with rotation sets up a circulation (driven by the temperature gradient) which carries angular momentum toward the equator against the viscous friction. Unfortunately also a large flux variation at the surface is obtained. Nevertheless it seems that the model has the basic requisites for correct dynamo action.

  13. Large-Scale Atmospheric Circulation Patterns Associated with Temperature Extremes as a Basis for Model Evaluation: Methodological Overview and Results

    Science.gov (United States)

    Loikith, P. C.; Broccoli, A. J.; Waliser, D. E.; Lintner, B. R.; Neelin, J. D.

    2015-12-01

    Anomalous large-scale circulation patterns often play a key role in the occurrence of temperature extremes. For example, large-scale circulation can drive horizontal temperature advection or influence local processes that lead to extreme temperatures, such as by inhibiting moderating sea breezes, promoting downslope adiabatic warming, and affecting the development of cloud cover. Additionally, large-scale circulation can influence the shape of temperature distribution tails, with important implications for the magnitude of future changes in extremes. As a result of the prominent role these patterns play in the occurrence and character of extremes, the way in which temperature extremes change in the future will be highly influenced by if and how these patterns change. It is therefore critical to identify and understand the key patterns associated with extremes at local to regional scales in the current climate and to use this foundation as a target for climate model validation. This presentation provides an overview of recent and ongoing work aimed at developing and applying novel approaches to identifying and describing the large-scale circulation patterns associated with temperature extremes in observations and using this foundation to evaluate state-of-the-art global and regional climate models. Emphasis is given to anomalies in sea level pressure and 500 hPa geopotential height over North America using several methods to identify circulation patterns, including self-organizing maps and composite analysis. Overall, evaluation results suggest that models are able to reproduce observed patterns associated with temperature extremes with reasonable fidelity in many cases. Model skill is often highest when and where synoptic-scale processes are the dominant mechanisms for extremes, and lower where sub-grid scale processes (such as those related to topography) are important. Where model skill in reproducing these patterns is high, it can be inferred that extremes are

  14. Advanced circulating fluidised bed technology (CFB) for large-scale solid biomass fuel firing power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jaentti, Timo; Zabetta, Edgardo Coda; Nuortimo, Kalle [Foster Wheeler Energia Oy, Varkaus (Finland)

    2013-04-01

    Worldwide the nations are taking initiatives to counteract global warming by reducing their greenhouse gas emissions. Efforts to increase boiler efficiency and the use of biomass and other solid renewable fuels are well in line with these objectives. Circulating fluidised bed boilers (CFB) are ideal for efficient power generation, capable to fire a broad variety of solid biomass fuels from small CHP plants to large utility power plants. Relevant boiler references in commercial operation are made for Finland and Poland.

  15. Combinations of large-scale circulation anomalies conducive to precipitation extremes in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Kašpar, Marek; Müller, Miloslav

    2014-01-01

    Roč. 138, March 2014 (2014), s. 205-212 ISSN 0169-8095 R&D Projects: GA ČR(CZ) GAP209/11/1990 Institutional support: RVO:68378289 Keywords : precipitation extreme * synoptic-scale cause * re-analysis * circulation anomaly Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.844, year: 2014 http://www.sciencedirect.com/science/article/pii/S0169809513003372

  16. Did Large-Scale Vaccination Drive Changes in the Circulating Rotavirus Population in Belgium?

    Science.gov (United States)

    Pitzer, Virginia E.; Bilcke, Joke; Heylen, Elisabeth; Crawford, Forrest W.; Callens, Michael; De Smet, Frank; Van Ranst, Marc; Zeller, Mark; Matthijnssens, Jelle

    2015-01-01

    Vaccination can place selective pressures on viral populations, leading to changes in the distribution of strains as viruses evolve to escape immunity from the vaccine. Vaccine-driven strain replacement is a major concern after nationwide rotavirus vaccine introductions. However, the distribution of the predominant rotavirus genotypes varies from year to year in the absence of vaccination, making it difficult to determine what changes can be attributed to the vaccines. To gain insight in the underlying dynamics driving changes in the rotavirus population, we fitted a hierarchy of mathematical models to national and local genotype-specific hospitalization data from Belgium, where large-scale vaccination was introduced in 2006. We estimated that natural- and vaccine-derived immunity was strongest against completely homotypic strains and weakest against fully heterotypic strains, with an intermediate immunity amongst partially heterotypic strains. The predominance of G2P[4] infections in Belgium after vaccine introduction can be explained by a combination of natural genotype fluctuations and weaker natural and vaccine-induced immunity against infection with strains heterotypic to the vaccine, in the absence of significant variation in strain-specific vaccine effectiveness against disease. However, the incidence of rotavirus gastroenteritis is predicted to remain low despite vaccine-driven changes in the distribution of genotypes. PMID:26687288

  17. Application of seeding and automatic differentiation in a large scale ocean circulation model

    Directory of Open Access Journals (Sweden)

    Frode Martinsen

    2005-07-01

    Full Text Available Computation of the Jacobian in a 3-dimensional general ocean circulation model is considered in this paper. The Jacobian matrix considered in this paper is square, large and sparse. When a large and sparse Jacobian is being computed, proper seeding is essential to reduce computational times. This paper presents a manually designed seeding motivated by the Arakawa-C staggered grid, and gives results for the manually designed seeding as compated to identity seeding and optimal seeding. Finite differences are computed for reference.

  18. Interannual variability of Central European mean temperature in January / February and its relation to the large-scale circulation

    International Nuclear Information System (INIS)

    Werner, P.C.; Storch, H. von

    1993-01-01

    The Central European temperature distribution field, as given by 11 stations (Fanoe, Hamburg, Potsdam, Jena, Frankfurt, Uccle, Hohenpeissenberg, Praha, Wien, Zuerich and Geneve), is analysed with respect to its year-to-year variability. January-February (JF) average temperatures are considered for the interval 1901-80. An Orthogonal Function (EOF) analysis reveals that the JF temperature variability is almost entirely controlled by one EOF with uniform sign. The second EOF represents only 7% of the total variance and describes a north-south gradient. The time coefficient of the first EOF is almost stationary whereas the second pattern describes a slight downward trend at the northern stations and a slight upward trend at the southern stations. The relationship of the temperature field to the large-scale circulation, represented by the North Atlantic/European sea-level pressure (SLP) field, is investigated by means of a Canonical Correlation (CCA) Analysis. Two CCA pairs are identified which account for most of the temperature year-to-year variance and which suggest plausible mechanisms. The CCA pairs fail, however, to consistently link the long-term temperature trends to changes in the large-scale circulation. In the output of a 100-year run with a coupled atmosphere-ocean model (ECHAM1/LSG), the same CCA pairs are found but the strength of the link between Central European temperature and North Atlantic SLP is markedly weaker than in the observed data. (orig.)

  19. A large-scale field assessment of carbon stocks in human-modified tropical forests.

    Science.gov (United States)

    Berenguer, Erika; Ferreira, Joice; Gardner, Toby Alan; Aragão, Luiz Eduardo Oliveira Cruz; De Camargo, Plínio Barbosa; Cerri, Carlos Eduardo; Durigan, Mariana; Cosme De Oliveira Junior, Raimundo; Vieira, Ima Célia Guimarães; Barlow, Jos

    2014-12-01

    Tropical rainforests store enormous amounts of carbon, the protection of which represents a vital component of efforts to mitigate global climate change. Currently, tropical forest conservation, science, policies, and climate mitigation actions focus predominantly on reducing carbon emissions from deforestation alone. However, every year vast areas of the humid tropics are disturbed by selective logging, understory fires, and habitat fragmentation. There is an urgent need to understand the effect of such disturbances on carbon stocks, and how stocks in disturbed forests compare to those found in undisturbed primary forests as well as in regenerating secondary forests. Here, we present the results of the largest field study to date on the impacts of human disturbances on above and belowground carbon stocks in tropical forests. Live vegetation, the largest carbon pool, was extremely sensitive to disturbance: forests that experienced both selective logging and understory fires stored, on average, 40% less aboveground carbon than undisturbed forests and were structurally similar to secondary forests. Edge effects also played an important role in explaining variability in aboveground carbon stocks of disturbed forests. Results indicate a potential rapid recovery of the dead wood and litter carbon pools, while soil stocks (0-30 cm) appeared to be resistant to the effects of logging and fire. Carbon loss and subsequent emissions due to human disturbances remain largely unaccounted for in greenhouse gas inventories, but by comparing our estimates of depleted carbon stocks in disturbed forests with Brazilian government assessments of the total forest area annually disturbed in the Amazon, we show that these emissions could represent up to 40% of the carbon loss from deforestation in the region. We conclude that conservation programs aiming to ensure the long-term permanence of forest carbon stocks, such as REDD+, will remain limited in their success unless they effectively

  20. Large-scale circulation associated with moisture intrusions into the Arctic during winter

    Science.gov (United States)

    Woods, Cian; Caballero, Rodrigo; Svensson, Gunilla

    2014-05-01

    intrusion events. A total of 298 events are objectively identified between 1990 and 2010 in the reanalysis dataset, an average of 14 per season, accounting for 28% of the total poleward moisture transport across 70N. Composites of sea level pressure and potential temperature on the 2 potential vorticity unit surface during intrusions show a large-scale blocking pattern to the east of each basin, deflecting midlatitude cyclones and their associated moisture poleward. The interannual variability of intrusions is strongly correlated with variability in winter-mean surface downward longwave radiation and skin temperature averaged over the Arctic. The 16 CMIP5 models are validated with respect to the reanalysis dataset and a subset of 7 models is chosen as best representing intrusions. Intrusions in the representative concentration pathway 8.5 scenario (RCP8.5) from these 7 models are analyzed between 2060 and 2100. Positive trends in the moisture transported by intrusions are noted. The mechanisms behind these trends are examined in each of the models, dynamically and thermodynamically, with regard to the positioning of the storm track and climatological jets in a moistening atmosphere.

  1. From trickle to flood: the large-scale, cryptic invasion of California by tropical fruit flies.

    Science.gov (United States)

    Papadopoulos, Nikos T; Plant, Richard E; Carey, James R

    2013-10-07

    Since 1954, when the first tropical tephritid fruit fly was detected in California, a total of 17 species in four genera and 11 386 individuals (adults/larvae) have been detected in the state at more than 3348 locations in 330 cities. We conclude from spatial mapping analyses of historical capture patterns and modelling that, despite the 250+ emergency eradication projects that have been directed against these pests by state and federal agencies, a minimum of five and as many as nine or more tephritid species are established and widespread, including the Mediterranean, Mexican and oriental fruit flies, and possibly the peach, guava and melon fruit flies. We outline and discuss the evidence for our conclusions, with particular attention to the incremental, chronic and insidious nature of the invasion, which involves ultra-small, barely detectable populations. We finish by considering the implications of our results for invasion biology and for science-based invasion policy.

  2. Evaluation of the Atlantic Multidecadal Oscillation Impact on Large-Scale Atmospheric Circulation in the Atlantic Region in Summer

    Science.gov (United States)

    Semenov, V. A.; Cherenkova, E. A.

    2018-02-01

    The influence of the Atlantic Multidecadal Oscillation (AMO) on large-scale atmospheric circulation in the Atlantic region in summer for the period of 1950-2015 is investigated. It is shown that the intensification of the summer North Atlantic Oscillation (NAO) with significant changes in sea level pressure anomalies in the main centers of action (over Greenland and the British Isles) occurred while the North Atlantic was cooler. Sea surface temperature anomalies, which are linked to the AMO in the summer season, affect both the NAO index and fluctuations of the Eastern Atlantic/Western Russia (EAWR) centers of action. The positive (negative) phase of the AMO is characterized by a combination of negative (positive) values of the NAO and EAWR indices. The dominance of the opposite phases of the teleconnection indices in summer during the warm North Atlantic and in its colder period resulted in differences in the regional climate in Europe.

  3. Large-scale connection between aerosol optical depth and summer monsoon circulation, and precipitation over northeast Asia

    Science.gov (United States)

    Kim, Sang-Woo; Yoon, Soon-Chang; Choi, Suk-Jin; Choi, In-Jin

    2010-05-01

    We investigated the large-scale connection between columnar aerosol loads and summer monsoon circulation, and also the precipitation over northeast Asia using aerosol optical depth (AOD) data obtained from the 8-year MODIS, AERONET Sun/sky radiometer, and precipitation data acquired under the Global Precipitation Climatology Project (GPCP). These high-quality data revealed the large-scale link between AOD and summer monsoon circulation, precipitation in July over northeast Asian countries, and their distinct spatial and annual variabilities. Compared to the mean AOD for the entire period of 2001-2008, the increase of almost 40-50% in the AOD value in July 2005 and July 2007 was found over the downwind regions of China (Yellow Sea, Korean peninsula, and East Sea), with negative precipitation anomalies. This can be attributable to the strong westerly confluent flows, between cyclone flows by continental thermal low centered over the northern China and anti-cyclonic flows by the western North Pacific High, which transport anthropogenic pollution aerosols emitted from east China to aforementioned downwind high AOD regions along the rim of the Pacific marine airmass. In July 2002, however, the easterly flows transported anthropogenic aerosols from east China to the southwestern part of China in July 2002. As a result, the AOD off the coast of China was dramatically reduced in spite of decreasing rainfall. From the calculation of the cross-correlation coefficient between MODIS-derived AOD anomalies and GPCP precipitation anomalies over the period 2001-2008, we found negative correlations over the areas encompassed by 105-115E and 30-35N and by 120-140E and 35-40N (Yellow Sea, Korean peninsula, and East Sea). This suggests that aerosol loads over these regions are easily influenced by the Asian monsoon flow system and associated precipitation.

  4. On unravelling mechanism of interplay between cloud and large scale circulation: a grey area in climate science

    Science.gov (United States)

    De, S.; Agarwal, N. K.; Hazra, Anupam; Chaudhari, Hemantkumar S.; Sahai, A. K.

    2018-04-01

    The interaction between cloud and large scale circulation is much less explored area in climate science. Unfolding the mechanism of coupling between these two parameters is imperative for improved simulation of Indian summer monsoon (ISM) and to reduce imprecision in climate sensitivity of global climate model. This work has made an effort to explore this mechanism with CFSv2 climate model experiments whose cloud has been modified by changing the critical relative humidity (CRH) profile of model during ISM. Study reveals that the variable CRH in CFSv2 has improved the nonlinear interactions between high and low frequency oscillations in wind field (revealed as internal dynamics of monsoon) and modulates realistically the spatial distribution of interactions over Indian landmass during the contrasting monsoon season compared to the existing CRH profile of CFSv2. The lower tropospheric wind error energy in the variable CRH simulation of CFSv2 appears to be minimum due to the reduced nonlinear convergence of error to the planetary scale range from long and synoptic scales (another facet of internal dynamics) compared to as observed from other CRH experiments in normal and deficient monsoons. Hence, the interplay between cloud and large scale circulation through CRH may be manifested as a change in internal dynamics of ISM revealed from scale interactive quasi-linear and nonlinear kinetic energy exchanges in frequency as well as in wavenumber domain during the monsoon period that eventually modify the internal variance of CFSv2 model. Conversely, the reduced wind bias and proper modulation of spatial distribution of scale interaction between the synoptic and low frequency oscillations improve the eastward and northward extent of water vapour flux over Indian landmass that in turn give feedback to the realistic simulation of cloud condensates attributing improved ISM rainfall in CFSv2.

  5. Carbon sequestration in Southeast Asian tropical peatlands over the Holocene period: large-scale hydrological controls

    Science.gov (United States)

    Dommain, R.; Couwenberg, J.; Cobb, A.; Gandois, L.; Kai, F.; Su'ut, N.; Abu Salim, K.; Harvey, C. F.; Glaser, P. H.; Joosten, H.

    2012-12-01

    Tropical peatlands are recognized as a significant sink of carbon dioxide and an important source of methane. Low latitude peatlands contain an estimated pool of 90 Pg C, of which ca. 70 Pg C is stored in Southeast Asian peatlands. However, the Holocene development of this carbon reservoir is poorly established. Here we provide a synthesis of carbon uptake rates by tropical peatlands in Southeast Asia across millennial timescales for the past 11,000 years. Our reconstruction of the carbon accumulation history for Borneo, Sumatra and Peninsular Malaysia is based on a synthesis of radiocarbon dated peat profiles, modeling of peatland extent, and a new carbon accumulation record from Brunei (NW-Borneo). During the early Holocene the first peatlands formed in southern Borneo under the influence of a strong monsoon and rapid rise in sea-level. The carbon accumulation rate (CAR) in these peatlands was on average 60 g C m-2 yr-1 at this time. Peatlands started to spread across the coastal lowlands of Borneo, Sumatra and Peninsular Malaysia after 8000 cal BP only when the rate of rising sea-level decreased. The major phase of coastal peatland initiation lasted from 7000 to 4000 cal BP. This period was marked by a Holocene precipitation maximum, suppressed El Niño activity, and the Holocene maximum in sea-level on the Sunda Shelf. The mean CAR of coastal peatlands at this time was 80 g C m-2 yr-1, with a Holocene peak of ~100 g C m-2 yr-1 from 4900 to 4500 cal BP. Significantly, atmospheric CO2 concentrations measured in the Taylor Dome Antarctic ice core indicate a plateau during this period of otherwise rising CO2 concentrations. During the Late Holocene CAR declined both in coastal peatlands (ca. 70 g C m-2 yr-1) and in southern Borneo (ca. 20 g C m-2 yr-1) in response to falling sea-levels and increased El Niño frequency and intensity. In fact, several peatlands in southern Borneo have stopped accumulating peat-carbon under higher El Niño activity. These results

  6. Improving rainfall representation for large-scale hydrological modelling of tropical mountain basins

    Science.gov (United States)

    Zulkafli, Zed; Buytaert, Wouter; Onof, Christian; Lavado, Waldo; Guyot, Jean-Loup

    2013-04-01

    Errors in the forcing data are sometimes overlooked in hydrological studies even when they could be the most important source of uncertainty. The latter particularly holds true in tropical countries with short historical records of rainfall monitoring and remote areas with sparse rain gauge network. In such instances, alternative data such as the remotely sensed precipitation from the TRMM (Tropical Rainfall Measuring Mission) satellite have been used. These provide a good spatial representation of rainfall processes but have been established in the literature to contain volumetric biases that may impair the results of hydrological modelling or worse, are compensated during model calibration. In this study, we analysed precipitation time series from the TMPA (TRMM Multiple Precipitation Algorithm, version 6) against measurements from over 300 gauges in the Andes and Amazon regions of Peru and Ecuador. We found moderately good monthly correlation between the pixel and gauge pairs but a severe underestimation of rainfall amounts and wet days. The discrepancy between the time series pairs is particularly visible over the east side of the Andes and may be attributed to localized and orographic-driven high intensity rainfall, which the satellite product may have limited skills at capturing due to technical and scale issues. This consequently results in a low bias in the simulated streamflow volumes further downstream. In comparison, with the recently released TMPA, version 7, the biases reduce. This work further explores several approaches to merge the two sources of rainfall measurements, each of a different spatial and temporal support, with the objective of improving the representation of rainfall in hydrological simulations. The methods used are (1) mean bias correction (2) data assimilation using Kalman filter Bayesian updating. The results are evaluated by means of (1) a comparison of runoff ratios (the ratio of the total runoff and the total precipitation over an

  7. Responses of the Tropical Atmospheric Circulation to Climate Change and Connection to the Hydrological Cycle

    Science.gov (United States)

    Ma, Jian; Chadwick, Robin; Seo, Kyong-Hwan; Dong, Changming; Huang, Gang; Foltz, Gregory R.; Jiang, Jonathan H.

    2018-05-01

    This review describes the climate change–induced responses of the tropical atmospheric circulation and their impacts on the hydrological cycle. We depict the theoretically predicted changes and diagnose physical mechanisms for observational and model-projected trends in large-scale and regional climate. The tropical circulation slows down with moisture and stratification changes, connecting to a poleward expansion of the Hadley cells and a shift of the intertropical convergence zone. Redistributions of regional precipitation consist of thermodynamic and dynamical components, including a strong offset between moisture increase and circulation weakening throughout the tropics. This allows other dynamical processes to dominate local circulation changes, such as a surface warming pattern effect over oceans and multiple mechanisms over land. To improve reliability in climate projections, more fundamental understandings of pattern formation, circulation change, and the balance of various processes redistributing land rainfall are suggested to be important.

  8. Large scale surveys suggest limited mercury availability in tropical north Queensland (Australia)

    International Nuclear Information System (INIS)

    Jardine, Timothy D.; Halliday, Ian A.; Howley, Christina; Sinnamon, Vivian; Bunn, Stuart E.

    2012-01-01

    Little is known about the threat of mercury (Hg) to consumers in food webs of Australia's wet–dry tropics. This is despite high concentrations in similar biomes elsewhere and a recent history of gold mining that could lead to a high degree of exposure for biota. We analysed Hg in water, sediments, invertebrates and fishes in rivers and estuaries of north Queensland, Australia to determine its availability and biomagnification in food webs. Concentrations in water and sediments were low relative to other regions of Hg concern, with only four of 138 water samples and five of 60 sediment samples above detection limits of 0.1 μg L −1 and 0.1 μg g −1 , respectively. Concentrations of Hg in fishes and invertebrates from riverine and wetland food webs were well below international consumption guidelines, including those in piscivorous fishes, likely due to low baseline concentrations and limited rates of biomagnification (average slope of log Hg vs. δ 15 N = 0.08). A large fish species of recreational, commercial, and cultural importance (the barramundi, Lates calcarifer), had low concentrations that were below consumption guidelines. Observed variation in Hg concentrations in this species was primarily explained by age and foraging location (floodplain vs. coastal), with floodplain feeders having higher Hg concentrations than those foraging at sea. These analyses suggest that there is a limited threat of Hg exposure for fish-eating consumers in this region. - Highlights: ► Hg concentrations in freshwaters and sediments of north Queensland were low. ► Biomagnification of Hg through riverine food webs was limited. ► Barramundi, a predatory fish, had low concentrations meaning low risk for consumers. ► Floodplain-feeding barramundi had higher Hg concentrations than coastal feeders.

  9. Variability of cold season surface air temperature over northeastern China and its linkage with large-scale atmospheric circulations

    Science.gov (United States)

    Zhuang, Yuanhuang; Zhang, Jingyong; Wang, Lin

    2018-05-01

    Cold temperature anomalies and extremes have profound effects on the society, the economy, and the environment of northeastern China (NEC). In this study, we define the cold season as the months from October to April, and investigate the variability of cold season surface air temperature (CSAT) over NEC and its relationships with large-scale atmospheric circulation patterns for the period 1981-2014. The empirical orthogonal function (EOF) analysis shows that the first EOF mode of the CSAT over NEC is characterized by a homogeneous structure that describes 92.2% of the total variance. The regionally averaged CSAT over NEC is closely linked with the Arctic Oscillation ( r = 0.62, 99% confidence level) and also has a statistically significant relation with the Polar/Eurasian pattern in the cold season. The positive phases of the Arctic Oscillation and the Polar/Eurasian pattern tend to result in a positive geopotential height anomaly over NEC and a weakened East Asian winter monsoon, which subsequently increase the CSAT over NEC by enhancing the downward solar radiation, strengthening the subsidence warming and warm air advection. Conversely, the negative phases of these two climate indices result in opposite regional atmospheric circulation anomalies and decrease the CSAT over NEC.

  10. Evolution of the large-scale atmospheric circulation in response to changing ice sheets over the last glacial cycle

    Directory of Open Access Journals (Sweden)

    M. Löfverström

    2014-07-01

    Full Text Available We present modelling results of the atmospheric circulation at the cold periods of marine isotope stage 5b (MIS 5b, MIS 4 and the Last Glacial Maximum (LGM, as well as the interglacial. The palaeosimulations are forced by ice-sheet reconstructions consistent with geological evidence and by appropriate insolation and greenhouse gas concentrations. The results suggest that the large-scale atmospheric winter circulation remained largely similar to the interglacial for a significant part of the glacial cycle. The proposed explanation is that the ice sheets were located in areas where their interaction with the mean flow is limited. However, the LGM Laurentide Ice Sheet induces a much larger planetary wave that leads to a zonalisation of the Atlantic jet. In summer, the ice-sheet topography dynamically induces warm temperatures in Alaska and central Asia that inhibits the expansion of the ice sheets into these regions. The warm temperatures may also serve as an explanation for westward propagation of the Eurasian Ice Sheet from MIS 4 to the LGM.

  11. Mid-latitude afforestation shifts general circulation and tropical precipitation.

    Science.gov (United States)

    Swann, Abigail L S; Fung, Inez Y; Chiang, John C H

    2012-01-17

    We show in climate model experiments that large-scale afforestation in northern mid-latitudes warms the Northern Hemisphere and alters global circulation patterns. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is unable to compensate with latent heat flux due to water limitation. Atmospheric circulation redistributes the anomalous energy absorbed in the northern hemisphere, in particular toward the south, through altering the Hadley circulation, resulting in the northward displacement of the tropical rain bands. Precipitation decreases over parts of the Amazon basin affecting productivity and increases over the Sahel and Sahara regions in Africa. We find that the response of climate to afforestation in mid-latitudes is determined by the amount of soil moisture available to plants with the greatest warming found in water-limited regions. Mid-latitude afforestation is found to have a small impact on modeled global temperatures and on global CO(2), but regional heating from the increase in forest cover is capable of driving unintended changes in circulation and precipitation. The ability of vegetation to affect remote circulation has implications for strategies for climate mitigation.

  12. Climate dynamics of South America during summer: Connections between the large-scale circulation and regional precipitation

    Science.gov (United States)

    Lenters, Johh Derick

    1997-05-01

    Relationships between the large-scale circulation and regional precipitation over South America during austral summer are examined using a GCM, linear model, and observational analyses. Emphasis is placed on understanding the origin of upper-tropospheric circulation features such as the Bolivian high and its effects on South American precipitation variability, particularly on the Central Andean Altiplano. Results from the linear model indicate that the Bolivian high and 'Nordeste low' are generated in response to precipitation over the Amazon basin, Central Andes, and South Atlantic convergence zone (SACZ), with African precipitation also playing a crucial role in the formation of the low. The direct mechanical and sensible heating effects of the Andes are minimal, acting only to induce a weak lee trough in midlatitudes and a shallow monsoonal circulation over the Central Andes. In the GCM the effects of the Andes include a strengthening of the Bolivian high and northward shift of the Nordeste low, primarily through changes in the precipitation field. The position of the Bolivian high is primarily determined by Amazonian precipitation and is little affected by the removal of the Andes. Strong subsidence to the west of the high is found to be important for the maintenance of the high's warm core, while large-scale convective overshooting to the east is responsible for a layer of cold air above the high. Observations from eight summer seasons reveal a close relationship between precipitation variability in the Central Andes and the position and intensity of the Bolivian high. The physical mechanisms of this connection are explored using composite, EOF, and correlation techniques. On intraseasonal to interannual timescales, rainy episodes on the Altiplano are found to be associated with warm, moist, poleward flow along the eastern flank of the Andes, often in conjunction with extratropical disturbances and a westward displacement of the SACZ. Corresponding to this

  13. Hydrometeorological variability on a large french catchment and its relation to large-scale circulation across temporal scales

    Science.gov (United States)

    Massei, Nicolas; Dieppois, Bastien; Fritier, Nicolas; Laignel, Benoit; Debret, Maxime; Lavers, David; Hannah, David

    2015-04-01

    In the present context of global changes, considerable efforts have been deployed by the hydrological scientific community to improve our understanding of the impacts of climate fluctuations on water resources. Both observational and modeling studies have been extensively employed to characterize hydrological changes and trends, assess the impact of climate variability or provide future scenarios of water resources. In the aim of a better understanding of hydrological changes, it is of crucial importance to determine how and to what extent trends and long-term oscillations detectable in hydrological variables are linked to global climate oscillations. In this work, we develop an approach associating large-scale/local-scale correlation, enmpirical statistical downscaling and wavelet multiresolution decomposition of monthly precipitation and streamflow over the Seine river watershed, and the North Atlantic sea level pressure (SLP) in order to gain additional insights on the atmospheric patterns associated with the regional hydrology. We hypothesized that: i) atmospheric patterns may change according to the different temporal wavelengths defining the variability of the signals; and ii) definition of those hydrological/circulation relationships for each temporal wavelength may improve the determination of large-scale predictors of local variations. The results showed that the large-scale/local-scale links were not necessarily constant according to time-scale (i.e. for the different frequencies characterizing the signals), resulting in changing spatial patterns across scales. This was then taken into account by developing an empirical statistical downscaling (ESD) modeling approach which integrated discrete wavelet multiresolution analysis for reconstructing local hydrometeorological processes (predictand : precipitation and streamflow on the Seine river catchment) based on a large-scale predictor (SLP over the Euro-Atlantic sector) on a monthly time-step. This approach

  14. Five hundred years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation

    Energy Technology Data Exchange (ETDEWEB)

    Pauling, Andreas [University of Bern, Institute of Geography, Bern (Switzerland); Luterbacher, Juerg; Wanner, Heinz [University of Bern, Institute of Geography, Bern (Switzerland); National Center of Competence in Research (NCCR) in Climate, Bern (Switzerland); Casty, Carlo [University of Bern, Climate and Environmental Physics Institute, Bern (Switzerland)

    2006-03-15

    We present seasonal precipitation reconstructions for European land areas (30 W to 40 E/30-71 N; given on a 0.5 x 0.5 resolved grid) covering the period 1500-1900 together with gridded reanalysis from 1901 to 2000 (Mitchell and Jones 2005). Principal component regression techniques were applied to develop this dataset. A large variety of long instrumental precipitation series, precipitation indices based on documentary evidence and natural proxies (tree-ring chronologies, ice cores, corals and a speleothem) that are sensitive to precipitation signals were used as predictors. Transfer functions were derived over the 1901-1983 calibration period and applied to 1500-1900 in order to reconstruct the large-scale precipitation fields over Europe. The performance (quality estimation based on unresolved variance within the calibration period) of the reconstructions varies over centuries, seasons and space. Highest reconstructive skill was found for winter over central Europe and the Iberian Peninsula. Precipitation variability over the last half millennium reveals both large interannual and decadal fluctuations. Applying running correlations, we found major non-stationarities in the relation between large-scale circulation and regional precipitation. For several periods during the last 500 years, we identified key atmospheric modes for southern Spain/northern Morocco and central Europe as representations of two precipitation regimes. Using scaled composite analysis, we show that precipitation extremes over central Europe and southern Spain are linked to distinct pressure patterns. Due to its high spatial and temporal resolution, this dataset allows detailed studies of regional precipitation variability for all seasons, impact studies on different time and space scales, comparisons with high-resolution climate models as well as analysis of connections with regional temperature reconstructions. (orig.)

  15. Wild pigs (Sus scrofa) mediate large-scale edge effects in a lowland tropical rainforest in Peninsular Malaysia.

    Science.gov (United States)

    Fujinuma, Junichi; Harrison, Rhett D

    2012-01-01

    Edge-effects greatly extend the area of tropical forests degraded through human activities. At Pasoh, Peninsular Malaysia, it has been suggested that soil disturbance by highly abundant wild pigs (Sus scrofa), which feed in adjacent Oil Palm plantations, may have mediated the invasion of Clidemia hirta (Melastomataceae) into the diverse tropical lowland rain forest. To investigate this hypothesis, we established three 1 km transects from the forest/Oil Palm plantation boundary into the forest interior. We recorded the distribution of soil disturbance by wild pigs, C. hirta abundance, and environmental variables. These data were analyzed using a hierarchical Bayesian model that incorporated spatial auto-correlation in the environmental variables. As predicted, soil disturbance by wild pigs declined with distance from forest edge and C. hirta abundance was correlated with the level of soil disturbance. Importantly there was no effect of distance on C. hirta abundance, after controlling for the effect of soil disturbance. Clidemia hirta abundance was also correlated with the presence of canopy openings, but there was no significant association between the occurrence of canopy openings and distance from the edge. Increased levels of soil disturbance and C. hirta abundance were still detectable approximately 1 km from the edge, demonstrating the potential for exceptionally large-scale animal mediated edge effects.

  16. Impact of large-scale circulation changes in the North Atlantic sector on the current and future Mediterranean winter hydroclimate

    Science.gov (United States)

    Barcikowska, Monika J.; Kapnick, Sarah B.; Feser, Frauke

    2018-03-01

    The Mediterranean region, located in the transition zone between the dry subtropical and wet European mid-latitude climate, is very sensitive to changes in the global mean climate state. Projecting future changes of the Mediterranean hydroclimate under global warming therefore requires dynamic climate models to reproduce the main mechanisms controlling regional hydroclimate with sufficiently high resolution to realistically simulate climate extremes. To assess future winter precipitation changes in the Mediterranean region we use the Geophysical Fluid Dynamics Laboratory high-resolution general circulation model for control simulations with pre-industrial greenhouse gas and aerosol concentrations which are compared to future scenario simulations. Here we show that the coupled model is able to reliably simulate the large-scale winter circulation, including the North Atlantic Oscillation and Eastern Atlantic patterns of variability, and its associated impacts on the mean Mediterranean hydroclimate. The model also realistically reproduces the regional features of daily heavy rainfall, which are absent in lower-resolution simulations. A five-member future projection ensemble, which assumes comparatively high greenhouse gas emissions (RCP8.5) until 2100, indicates a strong winter decline in Mediterranean precipitation for the coming decades. Consistent with dynamical and thermodynamical consequences of a warming atmosphere, derived changes feature a distinct bipolar behavior, i.e. wetting in the north—and drying in the south. Changes are most pronounced over the northwest African coast, where the projected winter precipitation decline reaches 40% of present values. Despite a decrease in mean precipitation, heavy rainfall indices show drastic increases across most of the Mediterranean, except the North African coast, which is under the strong influence of the cold Canary Current.

  17. Simulated pre-industrial climate in Bergen Climate Model (version 2: model description and large-scale circulation features

    Directory of Open Access Journals (Sweden)

    O. H. Otterå

    2009-11-01

    Full Text Available The Bergen Climate Model (BCM is a fully-coupled atmosphere-ocean-sea-ice model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate. Here, a pre-industrial multi-century simulation with an updated version of BCM is described and compared to observational data. The model is run without any form of flux adjustments and is stable for several centuries. The simulated climate reproduces the general large-scale circulation in the atmosphere reasonably well, except for a positive bias in the high latitude sea level pressure distribution. Also, by introducing an updated turbulence scheme in the atmosphere model a persistent cold bias has been eliminated. For the ocean part, the model drifts in sea surface temperatures and salinities are considerably reduced compared to earlier versions of BCM. Improved conservation properties in the ocean model have contributed to this. Furthermore, by choosing a reference pressure at 2000 m and including thermobaric effects in the ocean model, a more realistic meridional overturning circulation is simulated in the Atlantic Ocean. The simulated sea-ice extent in the Northern Hemisphere is in general agreement with observational data except for summer where the extent is somewhat underestimated. In the Southern Hemisphere, large negative biases are found in the simulated sea-ice extent. This is partly related to problems with the mixed layer parametrization, causing the mixed layer in the Southern Ocean to be too deep, which in turn makes it hard to maintain a realistic sea-ice cover here. However, despite some problematic issues, the pre-industrial control simulation presented here should still be appropriate for climate change studies requiring multi-century simulations.

  18. Temperature oscillation and the sloshing motion of the large-scale circulation in turbulent Rayleigh-Bénard convection

    Science.gov (United States)

    Xi, Heng-Dong; Chen, Xin; Xia, Ke-Qing

    2017-11-01

    We report an experimental study of the temperature oscillation and the sloshing motion of the large-scale circulation (LSC) in turbulent Rayleigh-Bénard convection in water. Temperature measurements were made in aspect ratio one cylindrical cell by probes put in fluid and embedded in the sidewall simultaneously, and located at the 1/4, 1/2 and 3/4 heights of the convection cell. The results show that the temperature measured in fluid contains information of both the LSC and the signature of the hot and cold plumes, while the temperature measured in sidewall only contains information of the LSC. It is found that the sloshing motion of the LSC can be measured by both the temperatures in fluid and in sidewall. We also studies the effect of cell tilting on the temperature oscillation and sloshing motion of the LSC. It is found that both the amplitude and the frequency of the temperature oscillation (and the sloshing motion) increase when the tilt angle increases, while the off-center distance of the sloshing motion of the LSC remains unchanged. This work is supported by the NSFC of China (Grant Nos. 11472094 and U1613227), the RGC of Hong Kong SAR (Grant No. 403712) and the 111 project of China (Grant No. B17037).

  19. A see-saw of pre-Columbian boom regions in southern Peru, determined by large-scale circulation changes

    Science.gov (United States)

    Mächtle, B.; Schittek, K.; Forbriger, M.; Schäbitz, F.; Eitel, B.

    2012-04-01

    Environmental changes and cultural transitions during several periods of Peruvian history show a strong coincidence between humid and dry climatic oscillations and the rise and decline of cultures. It is noteworthy, that alternating periods of geo-ecological fragility and stability occurred in time and space between the coastal Nasca region (14.5° S) and the high Andean northern Titicaca basin, just a few hundred kilometers to the east. Based on a multi-proxy palynological and sedimentological approach to reconstruct palaeoenvironmental changes, we found that the Nasca region received a maximum of precipitation during the archaeological boom times of the Early Horizon and the Early Intermediate Period (800 BC - 650 AD, Paracas and Nasca cultures) as well as during the late intermediate period (1150-1450 AD), whereas, in contrast, the Titicaca region further to the south-east experienced drought and cultural depression during that times. During the Middle Horizon (650 - 1150 AD), the Tiwanaku agronomy and culture boomed in the Titicaca region and expanded to the west, contemporaneous with a raised lake level and more humid conditions. In the Nasca region, runoff for irrigation purposes was reduced and less reliable due to drought. Considering a coincidence between environmental and cultural changes, we state that success and decline of civilizations were controlled by hydrological oscillations, triggering fertility as well as a critical loss of natural resources. In response to spatial changing resources, cultural foci were shifted. Therefore, the success of pre-Columbian civilizations was closely coupled to areas of geo-ecological favorability, which were directly controlled by distinct regional impacts of large-scale circulation mechanisms, including El Niño - Southern Oscillation (ENSO). Changes in the position of the intertropical convergence zone (ITCZ) and the Bolivian anticyclone determined meridional shifts in moisture transport across the Andes, which

  20. Breakdown of the large-scale circulation in Γ=1/2 rotating Rayleigh-Bénard flow.

    Science.gov (United States)

    Stevens, Richard J A M; Clercx, Herman J H; Lohse, Detlef

    2012-11-01

    Experiments and simulations of rotating Rayleigh-Bénard convection in cylindrical samples have revealed an increase in heat transport with increasing rotation rate. This heat transport enhancement is intimately related to a transition in the turbulent flow structure from a regime dominated by a large-scale circulation (LSC), consisting of a single convection roll, at no or weak rotation to a regime dominated by vertically aligned vortices at strong rotation. For a sample with an aspect ratio Γ=D/L=1 (D is the sample diameter and L is its height) the transition between the two regimes is indicated by a strong decrease in the LSC strength. In contrast, for Γ=1/2, Weiss and Ahlers [J. Fluid Mech. 688, 461 (2011)] revealed the presence of a LSC-like sidewall temperature signature beyond the critical rotation rate. They suggested that this might be due to the formation of a two-vortex state, in which one vortex extends vertically from the bottom into the sample interior and brings up warm fluid while another vortex brings down cold fluid from the top; this flow field would yield a sidewall temperature signature similar to that of the LSC. Here we show by direct numerical simulations for Γ=1/2 and parameters that allow direct comparison with experiment that the spatial organization of the vertically aligned vortical structures in the convection cell do indeed yield (for the time average) a sinusoidal variation of the temperature near the sidewall, as found in the experiment. This is also the essential and nontrivial difference with the Γ=1 sample, where the vertically aligned vortices are distributed randomly.

  1. Impacts of large-scale circulation on urban ambient concentrations of gaseous elemental mercury in New York, USA

    Directory of Open Access Journals (Sweden)

    H. Mao

    2017-09-01

    Full Text Available The impact of large-scale circulation on urban gaseous elemental mercury (GEM was investigated through analysis of 2008–2015 measurement data from an urban site in New York City (NYC, New York, USA. Distinct annual cycles were observed in 2009–2010 with mixing ratios in warm seasons (i.e., spring–summer 10–20 ppqv ( ∼  10–25 % higher than in cool seasons (i.e., fall–winter. This annual cycle was disrupted in 2011 by an anomalously strong influence of the US East Coast trough in that warm season and was reproduced in 2014 associated with a particularly strong Bermuda High. The US East Coast trough axis index (TAI and intensity index (TII were used to characterize the effect of the US East Coast trough on NYC GEM, especially in winter and summer. The intensity and position of the Bermuda High appeared to have a significant impact on GEM in warm seasons. Regional influence on NYC GEM was supported by the GEM–carbon monoxide (CO correlation with r of 0.17–0.69 (p ∼  0 in most seasons. Simulated regional and local anthropogenic contributions to wintertime NYC anthropogenically induced GEM concentrations were averaged at  ∼  75 % and 25 %, with interannual variation ranging over 67 %–83 % and 17 %–33 %, respectively. Results from this study suggest the possibility that the increasingly strong Bermuda High over the past decades could dominate over anthropogenic mercury emission control in affecting ambient concentrations of mercury via regional buildup and possibly enhancing natural and legacy emissions.

  2. Regime Behavior in Paleo-Reconstructed Streamflow: Attributions to Atmospheric Dynamics, Synoptic Circulation and Large-Scale Climate Teleconnection Patterns

    Science.gov (United States)

    Ravindranath, A.; Devineni, N.

    2017-12-01

    Studies have shown that streamflow behavior and dynamics have a significant link with climate and climate variability. Patterns of persistent regime behavior from extended streamflow records in many watersheds justify investigating large-scale climate mechanisms as potential drivers of hydrologic regime behavior and streamflow variability. Understanding such streamflow-climate relationships is crucial to forecasting/simulation systems and the planning and management of water resources. In this study, hidden Markov models are used with reconstructed streamflow to detect regime-like behaviors - the hidden states - and state transition phenomena. Individual extreme events and their spatial variability across the basin are then verified with the identified states. Wavelet analysis is performed to examine the signals over time in the streamflow records. Joint analyses of the climatic data in the 20th century and the identified states are undertaken to better understand the hydroclimatic connections within the basin as well as important teleconnections that influence water supply. Compositing techniques are used to identify atmospheric circulation patterns associated with identified states of streamflow. The grouping of such synoptic patterns and their frequency are then examined. Sliding time-window correlation analysis and cross-wavelet spectral analysis are performed to establish the synchronicity of basin flows to the identified synoptic and teleconnection patterns. The Missouri River Basin (MRB) is examined in this study, both as a means of better understanding the synoptic climate controls in this important watershed and as a case study for the techniques developed here. Initial wavelet analyses of reconstructed streamflow at major gauges in the MRB show multidecadal cycles in regime behavior.

  3. Changes in daily climate extremes in China and their connection to the large scale atmospheric circulation during 1961-2003

    Energy Technology Data Exchange (ETDEWEB)

    You, Qinglong [Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Laboratory of Tibetan Environment Changes and Land Surface Processes, Beijing (China); Friedrich-Schiller University Jena, Department of Geoinformatics, Jena (Germany); Graduate University of Chinese Academy of Sciences, Beijing (China); Kang, Shichang [Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Laboratory of Tibetan Environment Changes and Land Surface Processes, Beijing (China); State Key Laboratory of Cryospheric Science, Chinese Academy of Sciences, Lanzhou (China); Aguilar, Enric [Universitat Rovirai Virgili de Tarragona, Climate Change Research Group, Geography Unit, Tarragona (Spain); Pepin, Nick [University of Portsmouth, Department of Geography, Portsmouth (United Kingdom); Fluegel, Wolfgang-Albert [Friedrich-Schiller University Jena, Department of Geoinformatics, Jena (Germany); Yan, Yuping [National Climate Center, Beijing (China); Xu, Yanwei; Huang, Jie [Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Laboratory of Tibetan Environment Changes and Land Surface Processes, Beijing (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Zhang, Yongjun [Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Laboratory of Tibetan Environment Changes and Land Surface Processes, Beijing (China)

    2011-06-15

    negative magnitudes. This is inconsistent with changes of water vapor flux calculated from NCEP/NCAR reanalysis. Large scale atmospheric circulation changes derived from NCEP/NCAR reanalysis grids show that a strengthening anticyclonic circulation, increasing geopotential height and rapid warming over the Eurasian continent have contributed to the changes in climate extremes in China. (orig.)

  4. 20th century trends of drought conditions in the Mediterranean: the influence of large-scale circulation patterns.

    Science.gov (United States)

    Sousa, Pedro; Trigo, Ricardo; Garcia-Herrera, Ricardo

    2010-05-01

    Here we have used the Self Calibrated PDSI (scPDSI) proposed by Wells et al (2004) as a more appropriate approach to characterize drought conditions in the Mediterranean area. The scPDSI has been shown to perform better (than the original PDSI) when evaluating spatial and temporal drought characteristics for regions outside the USA (Schrier et al, 2005). Seasonal and annual trends for the 1901-2000, 1901-1950 and 1951-2000 periods were computed using the standard Mann-Kendall test for trend significance evaluation. However, statistical significance obtained with this test can be highly misleading because it does not take into account the low variability nature that dominates the seasonal evolution of scPDSI fields. We have now improved these results by employing a modified Mann-Kendall test for auto-correlated series (Hamed and Ramachandra, 1997), such as the scPDSI case. This development allowed for a better definition of the Mediterranean areas characterized by significant changes in the scPDSI, namely the largely negative trends that dominate the Mediterranean basin, with the exceptions of parts of eastern Turkey and northwestern Iberia, since initially these areas were overestimated. The spatio-temporal variability of these indices was evaluated with an EOF analysis, in order to reduce the large dimensionality of the fields under analysis. Spatial representation of the first EOF patterns shows that EOF 1 covers the entire Mediterranean basin (16.4% of EV), while EOF2 is dominated by a W-E dipole (10% EV). The following EOF patterns present smaller scale features, and explain smaller amounts of variance. The EOF patterns have also facilitated the definition of four sub-regions with large socio-economic relevance: 1) Iberia, 2) Italian Peninsula, 3) Balkans and 4) Turkey. Afterwards we perform a comprehensive analysis on the links between the scPDSI and the large-scale atmospheric circulation indices that affect the Mediterranean basin, namely; NAO, EA, and SCAND

  5. Local and regional effects of large scale atmospheric circulation patterns on winter wind power output in Western Europe

    Science.gov (United States)

    Zubiate, Laura; McDermott, Frank; Sweeney, Conor; O'Malley, Mark

    2014-05-01

    Recent studies (Brayshaw, 2009, Garcia-Bustamante, 2010, Garcia-Bustamante, 2013) have drawn attention to the sensitivity of wind speed distributions and likely wind energy power output in Western Europe to changes in low-frequency, large scale atmospheric circulation patterns such as the North Atlantic Oscillation (NAO). Wind speed variations and directional shifts as a function of the NAO state can be larger or smaller depending on the North Atlantic region that is considered. Wind speeds in Ireland and the UK for example are approximately 20 % higher during NAO + phases, and up to 30 % lower during NAO - phases relative to the long-term (30 year) climatological means. By contrast, in southern Europe, wind speeds are 15 % lower than average during NAO + phases and 15 % higher than average during NAO - phases. Crucially however, some regions such as Brittany in N.W. France have been identified in which there is negligible variability in wind speeds as a function of the NAO phase, as observed in the ERA-Interim 0.5 degree gridded reanalysis database. However, the magnitude of these effects on wind conditions is temporally and spatially non-stationary. As described by Comas-Bru and McDermott (2013) for temperature and precipitation, such non-stationarity is caused by the influence of two other patterns, the East Atlantic pattern, (EA), and the Scandinavian pattern, (SCA), which modulate the position of the NAO dipole. This phenomenon has also implications for wind speeds and directions, which has been assessed using the ERA-Interim reanalysis dataset and the indices obtained from the PC analysis of sea level pressure over the Atlantic region. In order to study the implications for power production, the interaction of the NAO and the other teleconnection patterns with local topography was also analysed, as well as how these interactions ultimately translate into wind power output. The objective is to have a better defined relationship between wind speed and power

  6. Probabilistic Water Availability Prediction in the Rio Grande Basin using Large-scale Circulation Indices as Precursor

    Science.gov (United States)

    Khedun, C. P.; Mishra, A. K.; Giardino, J. R.; Singh, V. P.

    2011-12-01

    Hydrometeorological conditions, and therefore water availability, is affected by large-scale circulation indices. In the Rio Grande, which is a transboundary basin shared between the United States and Mexico, the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) influence local hydrological conditions. Different sub-regions of the basin exhibit varying degrees of correlation, but in general, an increase (decrease) in runoff during El Niños (La Niñas) is noted. Positive PDO enhances the effect of El Niño and dampens the negative effect of La Niña, and when it is in its neutral/transition phase, La Niña dominates climatic conditions and reduces water availability. Further, lags of up to 3 months have been found between ENSO and precipitation in the basin. We hypothesize that (1) a trivariate statistical relationship can be established between the two climate indices and water availability, and (2) the relationship can be used to predict water availability based on projected PDO and ENSO conditions. We use copula to establish the dependence between climate indices and water availability. Water availability is generated from Noah land surface model (LSM), forced with the North American Land Data Assimilation System Phase 2 (NLDAS-2). The model is run within NASA GSFC's Land Information System. LSM generated runoff gives a more realistic picture of available surface water as it is not affected by anthropogenic changes, such as the construction of dams, diversions, and other land use land cover changes, which may obscure climatic influences. Marginals from climate indices and runoff are from different distribution families, thus conventional functional forms of multivariate frequency distributions cannot be employed. Copulas offer a viable alternative as marginals from different families can be combined into a joint distribution. Uncertainties in the statistical relationship can be determined and the statistical model can be used for

  7. Evolution of the Large Scale Circulation, Cloud Structure and Regional Water Cycle Associated with the South China Sea Monsoon During May-June, 1998

    Science.gov (United States)

    Lau, William K.-M.; Li, Xiao-Fan

    2001-01-01

    In this paper, changes in the large-scale circulation, cloud structures and regional water cycle associated with the evolution of the South China Sea (SCS) monsoon in May-June 1998 were investigated using data from the Tropical Rainfall Measuring Mission (TRMM) and field data from the South China Sea Monsoon Experiment (SCSMEX). Results showed that both tropical and extratropical processes strongly influenced the onset and evolution of the SCS monsoon. Prior to the onset of the SCS monsoon, enhanced convective activities associated with the Madden and Julian Oscillation were detected over the Indian Ocean, and the SCS was under the influence of the West Pacific Anticyclone (WPA) with prevailing low level easterlies and suppressed convection. Establishment of low-level westerlies across Indo-China, following the development of a Bay of Bengal depression played an important role in building up convective available potential energy over the SCS. The onset of SCS monsoon appeared to be triggered by the equatorward penetration of extratropical frontal system, which was established over the coastal region of southern China and Taiwan in early May. Convective activities over the SCS were found to vary inversely with those over the Yangtze River Valley (YRV). Analysis of TRMM microwave and precipitation radar data revealed that during the onset phase, convection over the northern SCS consisted of squall-type rain cell embedded in meso-scale complexes similar to extratropical systems. The radar Z-factor intensity indicated that SCS clouds possessed a bimodal distribution, with a pronounced signal (less than 30dBz) at a height of 2-3 km, and another one (less than 25 dBz) at the 8-10 km level, separated by a well-defined melting level indicated by a bright band at around 5-km level. The stratiform-to-convective cloud ratio was approximately 1:1 in the pre-onset phase, but increased to 5:1 in the active phase. Regional water budget calculations indicated that during the

  8. Large-Scale Mapping of Tree-Community Composition as a Surrogate of Forest Degradation in Bornean Tropical Rain Forests

    Directory of Open Access Journals (Sweden)

    Shogoro Fujiki

    2016-12-01

    quantitatively assess the spatial patterns of intactness in Bornean rain forests. Our approach can be used for large-scale assessments of tree diversity and forest intactness to monitor both the progress of Aichi Biodiversity Targets and the effectiveness of REDD+ biodiversity safeguards in production forests in the tropics.

  9. A simple algorithm for large-scale mapping of evergreen forests in tropical America, Africa and Asia

    Science.gov (United States)

    Xiangming Xiao; Chandrashekhar M. Biradar; Christina Czarnecki; Tunrayo Alabi; Michael Keller

    2009-01-01

    The areal extent and spatial distribution of evergreen forests in the tropical zones are important for the study of climate, carbon cycle and biodiversity. However, frequent cloud cover in the tropical regions makes mapping evergreen forests a challenging task. In this study we developed a simple and novel mapping algorithm that is based on the temporal profile...

  10. Effects of land cover change on the tropical circulation in a GCM

    Science.gov (United States)

    Jonko, Alexandra Karolina; Hense, Andreas; Feddema, Johannes Jan

    2010-09-01

    Multivariate statistics are used to investigate sensitivity of the tropical atmospheric circulation to scenario-based global land cover change (LCC), with the largest changes occurring in the tropics. Three simulations performed with the fully coupled Parallel Climate Model (PCM) are compared: (1) a present day control run; (2) a simulation with present day land cover and Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 greenhouse gas (GHG) projections; and (3) a simulation with SRES A2 land cover and GHG projections. Dimensionality of PCM data is reduced by projection onto a priori specified eigenvectors, consisting of Rossby and Kelvin waves produced by a linearized, reduced gravity model of the tropical circulation. A Hotelling T 2 test is performed on projection amplitudes. Effects of LCC evaluated by this method are limited to diabatic heating. A statistically significant and recurrent signal is detected for 33% of all tests performed for various combinations of parameters. Taking into account uncertainties and limitations of the present methodology, this signal can be interpreted as a Rossby wave response to prescribed LCC. The Rossby waves are shallow, large-scale motions, trapped at the equator and most pronounced in boreal summer. Differences in mass and flow fields indicate a shift of the tropical Walker circulation patterns with an anomalous subsidence over tropical South America.

  11. Wild Pigs (Sus scrofa) Mediate Large-Scale Edge Effects in a Lowland Tropical Rainforest in Peninsular Malaysia

    OpenAIRE

    Fujinuma, Junichi; Harrison, Rhett D.

    2012-01-01

    Edge-effects greatly extend the area of tropical forests degraded through human activities. At Pasoh, Peninsular Malaysia, it has been suggested that soil disturbance by highly abundant wild pigs (Sus scrofa), which feed in adjacent Oil Palm plantations, may have mediated the invasion of Clidemia hirta (Melastomataceae) into the diverse tropical lowland rain forest. To investigate this hypothesis, we established three 1 km transects from the forest/Oil Palm plantation boundary into the forest...

  12. Cascading Effects of Canopy Opening and Debris Deposition from a Large-Scale Hurricane Experiment in a Tropical Rain Forest

    Science.gov (United States)

    Aaron B. Shiels; Grizelle Gonzalez; D. Jean Lodge; Michael R Willig; Jess K. Zimmerman

    2015-01-01

    Intense hurricanes disturb many tropical forests, but the key mechanisms driving post-hurricane forest changes are not fully understood. In Puerto Rico, we used a replicated factorial experiment to determine the mechanisms of forest change associated with canopy openness and organic matter (debris) addition. Cascading effects from canopy openness accounted for...

  13. Extratropical Transition and Re-Intensification of Typhoon Toraji (2001): Large-Scale Circulations, Structural Characteristics, and Mechanism Analysis

    Science.gov (United States)

    Zhu, Xiande; Wu, Lixin; Wang, Qi

    2018-06-01

    With the use of data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis, the environment and structure of typhoon Toraji (2001) are investigated during the re-intensification (RI) stage of its extratropical transition (ET), a process in which a tropical cyclone transforms into an extratropical or mid-latitude cyclone. The results provide detailed insight into the ET system and identify the specific features of the system, including wind field, a cold and dry intrusion, and a frontal structure in the RI stage. The irrotational wind provides the values of upper-and lower-level jets within the transitioning tropical cyclone and the cyclone over Shandong Peninsula, accompanied with the reduced radius of maximum surface winds around the cyclone center in the lower troposphere. Simultaneously, dry air intrusion enhances the formation of fronts and leads to strong potential instability in the southwest and northeast quadrants. The distribution of frontogenesis shows that the tilting term associated with vertical motion dominates the positive frontogenesis surrounding the cyclone center, especially in the RI stage. The diagnostics of the kinetic energy budget suggest that the divergent kinetic energy generation whose time evolution corresponds well to that of cyclone center pressure is the primary factor for the development of Toraji in the lower troposphere. The ET of Toraji is a compound pattern that contains a development similar to that of a B-type extratropical cyclone within the maintaining phase and an A-type extratropical cyclone within the strengthening period, which corresponds to the distribution of the E-P fluxes with vertically downward propagation in the maintaining stage and upwards momentum in the strengthening phase.

  14. Sensitivity of local air quality to the interplay between small- and large-scale circulations: a large-eddy simulation study

    Directory of Open Access Journals (Sweden)

    T. Wolf-Grosse

    2017-06-01

    Full Text Available Street-level urban air pollution is a challenging concern for modern urban societies. Pollution dispersion models assume that the concentrations decrease monotonically with raising wind speed. This convenient assumption breaks down when applied to flows with local recirculations such as those found in topographically complex coastal areas. This study looks at a practically important and sufficiently common case of air pollution in a coastal valley city. Here, the observed concentrations are determined by the interaction between large-scale topographically forced and local-scale breeze-like recirculations. Analysis of a long observational dataset in Bergen, Norway, revealed that the most extreme cases of recurring wintertime air pollution episodes were accompanied by increased large-scale wind speeds above the valley. Contrary to the theoretical assumption and intuitive expectations, the maximum NO2 concentrations were not found for the lowest 10 m ERA-Interim wind speeds but in situations with wind speeds of 3 m s−1. To explain this phenomenon, we investigated empirical relationships between the large-scale forcing and the local wind and air quality parameters. We conducted 16 large-eddy simulation (LES experiments with the Parallelised Large-Eddy Simulation Model (PALM for atmospheric and oceanic flows. The LES accounted for the realistic relief and coastal configuration as well as for the large-scale forcing and local surface condition heterogeneity in Bergen. They revealed that emerging local breeze-like circulations strongly enhance the urban ventilation and dispersion of the air pollutants in situations with weak large-scale winds. Slightly stronger large-scale winds, however, can counteract these local recirculations, leading to enhanced surface air stagnation. Furthermore, this study looks at the concrete impact of the relative configuration of warmer water bodies in the city and the major transport corridor. We found that a

  15. Sensitivity of local air quality to the interplay between small- and large-scale circulations: a large-eddy simulation study

    Science.gov (United States)

    Wolf-Grosse, Tobias; Esau, Igor; Reuder, Joachim

    2017-06-01

    Street-level urban air pollution is a challenging concern for modern urban societies. Pollution dispersion models assume that the concentrations decrease monotonically with raising wind speed. This convenient assumption breaks down when applied to flows with local recirculations such as those found in topographically complex coastal areas. This study looks at a practically important and sufficiently common case of air pollution in a coastal valley city. Here, the observed concentrations are determined by the interaction between large-scale topographically forced and local-scale breeze-like recirculations. Analysis of a long observational dataset in Bergen, Norway, revealed that the most extreme cases of recurring wintertime air pollution episodes were accompanied by increased large-scale wind speeds above the valley. Contrary to the theoretical assumption and intuitive expectations, the maximum NO2 concentrations were not found for the lowest 10 m ERA-Interim wind speeds but in situations with wind speeds of 3 m s-1. To explain this phenomenon, we investigated empirical relationships between the large-scale forcing and the local wind and air quality parameters. We conducted 16 large-eddy simulation (LES) experiments with the Parallelised Large-Eddy Simulation Model (PALM) for atmospheric and oceanic flows. The LES accounted for the realistic relief and coastal configuration as well as for the large-scale forcing and local surface condition heterogeneity in Bergen. They revealed that emerging local breeze-like circulations strongly enhance the urban ventilation and dispersion of the air pollutants in situations with weak large-scale winds. Slightly stronger large-scale winds, however, can counteract these local recirculations, leading to enhanced surface air stagnation. Furthermore, this study looks at the concrete impact of the relative configuration of warmer water bodies in the city and the major transport corridor. We found that a relatively small local water

  16. A new classification of large-scale climate regimes around the Tibetan Plateau based on seasonal circulation patterns

    Directory of Open Access Journals (Sweden)

    Xin-Gang Dai

    2017-03-01

    Full Text Available This study aims to develop a large-scale climate classification for investigating the characteristics of the climate regimes around the Tibetan Plateau based on seasonal precipitation, moisture transport and moisture divergence using in situ observations and ERA40 reanalysis data. The results indicate that the climate can be attributed to four regimes around the Plateau. They situate in East Asia, South Asia, Central Asia and the semi-arid zone in northern Central Asia throughout the dryland of northwestern China, in addition to the Köppen climate classification. There are different collocations of seasonal temperature and precipitation: 1 in phase for the East and South Asia monsoon regimes, 2 anti-phase for the Central Asia regime, 3 out-of-phase for the westerly regime. The seasonal precipitation concentrations are coupled with moisture divergence, i.e., moisture convergence coincides with the Asian monsoon zone and divergence appears over the Mediterranean-like arid climate region and westerly controlled area in the warm season, while it reverses course in the cold season. In addition, moisture divergence is associated with meridional moisture transport. The northward/southward moisture transport corresponds to moisture convergence/divergence, indicating that the wet and dry seasons are, to a great extent, dominated by meridional moisture transport in these regions. The climate mean southward transport results in the dry-cold season of the Asian monsoon zone and the dry-warm season, leading to desertification or land degradation in Central Asia and the westerly regime zone. The mean-wind moisture transport (MMT is the major contributor to total moisture transport, while persistent northward transient eddy moisture transport (TEMT plays a key role in dry season precipitation, especially in the Asian monsoon zone. The persistent TEMT divergence is an additional mechanism of the out-of-phase collocation in the westerly regime zone. In addition

  17. Modelling of large-scale structures arising under developed turbulent convection in a horizontal fluid layer (with application to the problem of tropical cyclone origination

    Directory of Open Access Journals (Sweden)

    G. V. Levina

    2000-01-01

    Full Text Available The work is concerned with the results of theoretical and laboratory modelling the processes of the large-scale structure generation under turbulent convection in the rotating-plane horizontal layer of an incompressible fluid with unstable stratification. The theoretical model describes three alternative ways of creating unstable stratification: a layer heating from below, a volumetric heating of a fluid with internal heat sources and combination of both factors. The analysis of the model equations show that under conditions of high intensity of the small-scale convection and low level of heat loss through the horizontal layer boundaries a long wave instability may arise. The condition for the existence of an instability and criterion identifying the threshold of its initiation have been determined. The principle of action of the discovered instability mechanism has been described. Theoretical predictions have been verified by a series of experiments on a laboratory model. The horizontal dimensions of the experimentally-obtained long-lived vortices are 4÷6 times larger than the thickness of the fluid layer. This work presents a description of the laboratory setup and experimental procedure. From the geophysical viewpoint the examined mechanism of the long wave instability is supposed to be adequate to allow a description of the initial step in the evolution of such large-scale vortices as tropical cyclones - a transition form the small-scale cumulus clouds to the state of the atmosphere involving cloud clusters (the stage of initial tropical perturbation.

  18. Large-scale Circulation Control of the Occurrence of Low-level Turbulence at Hong Kong International Airport

    Science.gov (United States)

    Leung, Marco Y. T.; Zhou, Wen; Shun, Chi-Ming; Chan, Pak-Wai

    2018-04-01

    This study identifies the atmospheric circulation features that are favorable for the occurrence of low-level turbulence at Hong Kong International Airport [below 1600 feet (around 500 m)]. By using LIDAR data at the airport, turbulence and nonturbulence cases are selected. It is found that the occurrence of turbulence is significantly related to the strength of the southerly wind at 850 hPa over the South China coast. On the other hand, the east-west wind at this height demonstrates a weak relation to the occurrence. This suggests that turbulence is generated by flow passing Lantau Island from the south. The southerly wind also transports moisture from the South China Sea to Hong Kong, reducing local stability. This is favorable for the development of strong turbulence. It is also noted that the strong southerly wind during the occurrence of low-level turbulence is contributed by an anomalous zonal gradient of geopotential in the lower troposphere over the South China Sea. This gradient is caused by the combination of variations at different timescales. These are the passage of synoptic extratropical cyclones and anticyclones and the intraseasonal variation in the western North Pacific subtropical high. The seasonal variation in geopotential east of the Tibetan Plateau leads to a seasonal change in meridional wind, by which the frequency of low-level turbulence is maximized in spring and minimized in autumn.

  19. Weakened tropical circulation and reduced precipitation in response to geoengineering

    International Nuclear Information System (INIS)

    Ferraro, Angus J; Highwood, Eleanor J; Charlton-Perez, Andrew J

    2014-01-01

    Geoengineering by injection of reflective aerosols into the stratosphere has been proposed as a way to counteract the warming effect of greenhouse gases by reducing the intensity of solar radiation reaching the surface. Here, climate model simulations are used to examine the effect of geoengineering on the tropical overturning circulation. The strength of the circulation is related to the atmospheric static stability and has implications for tropical rainfall. The tropical circulation is projected to weaken under anthropogenic global warming. Geoengineering with stratospheric sulfate aerosol does not mitigate this weakening of the circulation. This response is due to a fast adjustment of the troposphere to radiative heating from the aerosol layer. This effect is not captured when geoengineering is modelled as a reduction in total solar irradiance, suggesting caution is required when interpreting model results from solar dimming experiments as analogues for stratospheric aerosol geoengineering. (letter)

  20. Determining tropical cyclone inland flooding loss on a large scale through a new flood peak ratio-based methodology

    International Nuclear Information System (INIS)

    Czajkowski, Jeffrey; Michel-Kerjan, Erwann; Villarini, Gabriele; Smith, James A

    2013-01-01

    In recent years, the United States has been severely affected by numerous tropical cyclones (TCs) which have caused massive damages. While media attention mainly focuses on coastal losses from storm surge, these TCs have inflicted significant devastation inland as well. Yet, little is known about the relationship between TC-related inland flooding and economic losses. Here we introduce a novel methodology that first successfully characterizes the spatial extent of inland flooding, and then quantifies its relationship with flood insurance claims. Hurricane Ivan in 2004 is used as illustration. We empirically demonstrate in a number of ways that our quantified inland flood magnitude produces a very good representation of the number of inland flood insurance claims experienced. These results highlight the new technological capabilities that can lead to a better risk assessment of inland TC flood. This new capacity will be of tremendous value to a number of public and private sector stakeholders dealing with disaster preparedness. (letter)

  1. Large-scale atmospheric circulation biases and changes in global climate model simulations and their importance for climate change in Central Europe

    Directory of Open Access Journals (Sweden)

    A. P. van Ulden

    2006-01-01

    Full Text Available The quality of global sea level pressure patterns has been assessed for simulations by 23 coupled climate models. Most models showed high pattern correlations. With respect to the explained spatial variance, many models showed serious large-scale deficiencies, especially at mid-latitudes. Five models performed well at all latitudes and for each month of the year. Three models had a reasonable skill. We selected the five models with the best pressure patterns for a more detailed assessment of their simulations of the climate in Central Europe. We analysed observations and simulations of monthly mean geostrophic flow indices and of monthly mean temperature and precipitation. We used three geostrophic flow indices: the west component and south component of the geostrophic wind at the surface and the geostrophic vorticity. We found that circulation biases were important, and affected precipitation in particular. Apart from these circulation biases, the models showed other biases in temperature and precipitation, which were for some models larger than the circulation induced biases. For the 21st century the five models simulated quite different changes in circulation, precipitation and temperature. Precipitation changes appear to be primarily caused by circulation changes. Since the models show widely different circulation changes, especially in late summer, precipitation changes vary widely between the models as well. Some models simulate severe drying in late summer, while one model simulates significant precipitation increases in late summer. With respect to the mean temperature the circulation changes were important, but not dominant. However, changes in the distribution of monthly mean temperatures, do show large indirect influences of circulation changes. Especially in late summer, two models simulate very strong warming of warm months, which can be attributed to severe summer drying in the simulations by these models. The models differ also

  2. The impact of changes in parameterizations of surface drag and vertical diffusion on the large-scale circulation in the Community Atmosphere Model (CAM5)

    Science.gov (United States)

    Lindvall, Jenny; Svensson, Gunilla; Caballero, Rodrigo

    2017-06-01

    Simulations with the Community Atmosphere Model version 5 (CAM5) are used to analyze the sensitivity of the large-scale circulation to changes in parameterizations of orographic surface drag and vertical diffusion. Many GCMs and NWP models use enhanced turbulent mixing in stable conditions to improve simulations, while CAM5 cuts off all turbulence at high stabilities and instead employs a strong orographic surface stress parameterization, known as turbulent mountain stress (TMS). TMS completely dominates the surface stress over land and reduces the near-surface wind speeds compared to simulations without TMS. It is found that TMS is generally beneficial for the large-scale circulation as it improves zonal wind speeds, Arctic sea level pressure and zonal anomalies of the 500-hPa stream function, compared to ERA-Interim. It also alleviates atmospheric blocking frequency biases in the Northern Hemisphere. Using a scheme that instead allows for a modest increase of turbulent diffusion at higher stabilities only in the planetary boundary layer (PBL) appears to in some aspects have a similar, although much smaller, beneficial effect as TMS. Enhanced mixing throughout the atmospheric column, however, degrades the CAM5 simulation. Evaluating the simulations in comparison with detailed measurements at two locations reveals that TMS is detrimental for the PBL at the flat grassland ARM Southern Great Plains site, giving too strong wind turning and too deep PBLs. At the Sodankylä forest site, the effect of TMS is smaller due to the larger local vegetation roughness. At both sites, all simulations substantially overestimate the boundary layer ageostrophic flow.

  3. 2012/13 abnormal cold winter in Japan associated with Large-scale Atmospheric Circulation and Local Sea Surface Temperature over the Sea of Japan

    Science.gov (United States)

    Ando, Y.; Ogi, M.; Tachibana, Y.

    2013-12-01

    On Japan, wintertime cold wave has social, economic, psychological and political impacts because of the lack of atomic power stations in the era of post Fukushima world. The colder winter is the more electricity is needed. Wintertime weather of Japan and its prediction has come under the world spotlight. The winter of 2012/13 in Japan was abnormally cold, and such a cold winter has persisted for 3 years. Wintertime climate of Japan is governed by some dominant modes of the large-scale atmospheric circulations. Yasunaka and Hanawa (2008) demonstrated that the two dominant modes - Arctic Oscillation (AO) and Western Pacific (WP) pattern - account for about 65% of the interannual variation of the wintertime mean surface air temperature of Japan. A negative AO brings about cold winter in Japan. In addition, a negative WP also brings about cold winter in Japan. Looking back to the winter of 2012/13, both the negative AO and negative WP continued from October through December. If the previous studies were correct, it would have been extremely very cold from October through December. In fact, in December, in accordance with previous studies, it was colder than normal. Contrary to the expectation, in October and November, it was, however, warmer than normal. This discrepancy signifies that an additional hidden circumstance that heats Japan overwhelms these large-scale atmospheric circulations that cool Japan. In this study, we therefore seek an additional cause of wintertime climate of Japan particularly focusing 2012 as well as the AO and WP. We found that anomalously warm oceanic temperature surrounding Japan overwhelmed influences of the AO or WP. Unlike the inland climate, the island climate can be strongly influenced by surrounding ocean temperature, suggesting that large-scale atmospheric patterns alone do not determine the climate of islands. (a) Time series of a 5-day running mean AO index (blue) as defined by Ogi et al., (2004), who called it the SVNAM index. For

  4. Reconstructions of spring/summer precipitation for the Eastern Mediterranean from tree-ring widths and its connection to large-scale atmospheric circulation

    Energy Technology Data Exchange (ETDEWEB)

    Touchan, Ramzi; Funkhouser, Gary; Hughes, Malcolm K. [The University of Arizona, Laboratory of Tree-Ring Research, Tucson, AZ (United States); Xoplaki, Elena; Luterbacher, Juerg [University of Bern, Institute of Geography and NCCR Climate, Bern (Switzerland); Erkan, Nesat [Southwest Anatolia Forest Research Institute (SAFRI), Antalya (Turkey); Akkemik, Uenal [University of Istanbul, Faculty of Forestry, Department of Forest Botany, Bahcekoey-Istanbul (Turkey); Stephan, Jean [Ministry of Agriculture, Forestry Department, Beirut (Lebanon)

    2005-07-01

    This study represents the first large-scale systematic dendroclimatic sampling focused on developing chronologies from different species in the eastern Mediterranean region. Six reconstructions were developed from chronologies ranging in length from 115 years to 600 years. The first reconstruction (1885-2000) was derived from principal components (PCs) of 36 combined chronologies. The remaining five, 1800-2000, 1700-2000, 1600-2000, 1500-2000 and 1400-2000 were developed from PCs of 32, 18, 14, 9, and 7 chronologies, respectively. Calibration and verification statistics for the period 1931-2000 show good levels of skill for all reconstructions. The longest period of consecutive dry years, defined as those with less than 90% of the mean of the observed May-August precipitation, was 5 years (1591-1595) and occurred only once during the last 600 years. The longest reconstructed wet period was 5 years (1601-1605 and 1751-1755). No long term trends were found in May-August precipitation during the last few centuries. Regression maps are used to identify the influence of large-scale atmospheric circulation on regional precipitation. In general, tree-ring indices are influenced by May-August precipitation, which is driven by anomalous below (above) normal pressure at all atmospheric levels and by convection (subsidence) and small pressure gradients at sea level. These atmospheric conditions also control the anomaly surface air temperature distribution which indicates below (above) normal values in the southern regions and warmer (cooler) conditions north of around 40 N. A compositing technique is used to extract information on large-scale climate signals from extreme wet and dry summers for the second half of the twentieth century and an independent reconstruction over the last 237 years. Similar main modes of atmospheric patterns and surface air temperature distribution related to extreme dry and wet summers were identified both for the most recent 50 years and the last

  5. Long-term dynamics of tropical walking sticks in response to multiple large-scale and intense disturbances.

    Science.gov (United States)

    Willig, Michael R; Presley, Steven J; Bloch, Christopher P

    2011-02-01

    Understanding the effects of disturbance and secondary succession on spatio-temporal patterns in the abundance of species is stymied by a lack of long-term demographic data, especially in response to infrequent and high intensity disturbances, such as hurricanes. Moreover, resistance and resilience to hurricane-induced disturbance may be mediated by legacies of previous land use, although such interactive effects are poorly understood, especially in tropical environments. We address these central issues in disturbance ecology by analyzing an extensive dataset, spanning the impacts of Hurricanes Hugo and Georges, on the abundance of a Neotropical walking stick, Lamponius portoricensis, in tabonuco rainforest of Puerto Rico during the wet and dry seasons from 1991 to 2007. By synthesizing data from two proximate sites in tabonuco forest, we show that resistance to Hurricane Hugo (97% reduction in abundance) was much less than resistance to Hurricane Georges (21% reduction in abundance). Based on a powerful statistical approach (generalized linear mixed-effects models with Poisson error terms), we documented that the temporal trajectories of abundance during secondary succession (i.e., patterns of resilience) differed between hurricanes and among historical land use categories, but that the effects of hurricanes and land use histories were independent of each other. These complex results likely arise because of differences in the intensities of the two hurricanes with respect to microclimatic effects (temperature and moisture) in the forest understory, as well as to time-lags in the response of L. portoricensis to changes in the abundance and distribution of preferred food plants (Piper) in post-hurricane environments.

  6. Finding Tropical Cyclones on a Cloud Computing Cluster: Using Parallel Virtualization for Large-Scale Climate Simulation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hasenkamp, Daren; Sim, Alexander; Wehner, Michael; Wu, Kesheng

    2010-09-30

    Extensive computing power has been used to tackle issues such as climate changes, fusion energy, and other pressing scientific challenges. These computations produce a tremendous amount of data; however, many of the data analysis programs currently only run a single processor. In this work, we explore the possibility of using the emerging cloud computing platform to parallelize such sequential data analysis tasks. As a proof of concept, we wrap a program for analyzing trends of tropical cyclones in a set of virtual machines (VMs). This approach allows the user to keep their familiar data analysis environment in the VMs, while we provide the coordination and data transfer services to ensure the necessary input and output are directed to the desired locations. This work extensively exercises the networking capability of the cloud computing systems and has revealed a number of weaknesses in the current cloud system software. In our tests, we are able to scale the parallel data analysis job to a modest number of VMs and achieve a speedup that is comparable to running the same analysis task using MPI. However, compared to MPI based parallelization, the cloud-based approach has a number of advantages. The cloud-based approach is more flexible because the VMs can capture arbitrary software dependencies without requiring the user to rewrite their programs. The cloud-based approach is also more resilient to failure; as long as a single VM is running, it can make progress while as soon as one MPI node fails the whole analysis job fails. In short, this initial work demonstrates that a cloud computing system is a viable platform for distributed scientific data analyses traditionally conducted on dedicated supercomputing systems.

  7. Finding Tropical Cyclones on a Cloud Computing Cluster: Using Parallel Virtualization for Large-Scale Climate Simulation Analysis

    International Nuclear Information System (INIS)

    Hasenkamp, Daren; Sim, Alexander; Wehner, Michael; Wu, Kesheng

    2010-01-01

    Extensive computing power has been used to tackle issues such as climate changes, fusion energy, and other pressing scientific challenges. These computations produce a tremendous amount of data; however, many of the data analysis programs currently only run a single processor. In this work, we explore the possibility of using the emerging cloud computing platform to parallelize such sequential data analysis tasks. As a proof of concept, we wrap a program for analyzing trends of tropical cyclones in a set of virtual machines (VMs). This approach allows the user to keep their familiar data analysis environment in the VMs, while we provide the coordination and data transfer services to ensure the necessary input and output are directed to the desired locations. This work extensively exercises the networking capability of the cloud computing systems and has revealed a number of weaknesses in the current cloud system software. In our tests, we are able to scale the parallel data analysis job to a modest number of VMs and achieve a speedup that is comparable to running the same analysis task using MPI. However, compared to MPI based parallelization, the cloud-based approach has a number of advantages. The cloud-based approach is more flexible because the VMs can capture arbitrary software dependencies without requiring the user to rewrite their programs. The cloud-based approach is also more resilient to failure; as long as a single VM is running, it can make progress while as soon as one MPI node fails the whole analysis job fails. In short, this initial work demonstrates that a cloud computing system is a viable platform for distributed scientific data analyses traditionally conducted on dedicated supercomputing systems.

  8. The variability of tropical ice cloud properties as a function of the large-scale context from ground-based radar-lidar observations over Darwin, Australia

    Science.gov (United States)

    Protat, A.; Delanoë, J.; May, P. T.; Haynes, J.; Jakob, C.; O'Connor, E.; Pope, M.; Wheeler, M. C.

    2011-08-01

    The high complexity of cloud parameterizations now held in models puts more pressure on observational studies to provide useful means to evaluate them. One approach to the problem put forth in the modelling community is to evaluate under what atmospheric conditions the parameterizations fail to simulate the cloud properties and under what conditions they do a good job. It is the ambition of this paper to characterize the variability of the statistical properties of tropical ice clouds in different tropical "regimes" recently identified in the literature to aid the development of better process-oriented parameterizations in models. For this purpose, the statistical properties of non-precipitating tropical ice clouds over Darwin, Australia are characterized using ground-based radar-lidar observations from the Atmospheric Radiation Measurement (ARM) Program. The ice cloud properties analysed are the frequency of ice cloud occurrence, the morphological properties (cloud top height and thickness), and the microphysical and radiative properties (ice water content, visible extinction, effective radius, and total concentration). The variability of these tropical ice cloud properties is then studied as a function of the large-scale cloud regimes derived from the International Satellite Cloud Climatology Project (ISCCP), the amplitude and phase of the Madden-Julian Oscillation (MJO), and the large-scale atmospheric regime as derived from a long-term record of radiosonde observations over Darwin. The vertical variability of ice cloud occurrence and microphysical properties is largest in all regimes (1.5 order of magnitude for ice water content and extinction, a factor 3 in effective radius, and three orders of magnitude in concentration, typically). 98 % of ice clouds in our dataset are characterized by either a small cloud fraction (smaller than 0.3) or a very large cloud fraction (larger than 0.9). In the ice part of the troposphere three distinct layers characterized by

  9. Convective and large-scale mass flux profiles over tropical oceans determined from synergistic analysis of a suite of satellite observations

    Science.gov (United States)

    Masunaga, Hirohiko; Luo, Zhengzhao Johnny

    2016-07-01

    A new, satellite-based methodology is developed to evaluate convective mass flux and large-scale total mass flux. To derive the convective mass flux, candidate profiles of in-cloud vertical velocity are first constructed with a simple plume model under the constraint of ambient sounding and then narrowed down to the solution that matches satellite-derived cloud top buoyancy. Meanwhile, the large-scale total mass flux is provided separately from satellite soundings by a method developed previously. All satellite snapshots are sorted into a composite time series that delineates the evolution of a vigorous and organized convective system. Principal findings are the following. First, convective mass flux is modulated primarily by convective cloud cover, with the intensity of individual convection being less variable over time. Second, convective mass flux dominates the total mass flux only during the early hours of the convective evolution; as convective system matures, a residual mass flux builds up in the mass flux balance that is reminiscent of stratiform dynamics. The method developed in this study is expected to be of unique utility for future observational diagnosis of tropical convective dynamics and for evaluation of global climate model cumulus parameterizations in a global sense.

  10. Assimilating Non-linear Effects of Customized Large-Scale Climate Predictors on Downscaled Precipitation over the Tropical Andes

    Science.gov (United States)

    Molina, J. M.; Zaitchik, B. F.

    2016-12-01

    Recent findings considering high CO2 emission scenarios (RCP8.5) suggest that the tropical Andes may experience a massive warming and a significant precipitation increase (decrease) during the wet (dry) seasons by the end of the 21st century. Variations on rainfall-streamflow relationships and seasonal crop yields significantly affect human development in this region and make local communities highly vulnerable to climate change and variability. We developed an expert-informed empirical statistical downscaling (ESD) algorithm to explore and construct robust global climate predictors to perform skillful RCP8.5 projections of in-situ March-May (MAM) precipitation required for impact modeling and adaptation studies. We applied our framework to a topographically-complex region of the Colombian Andes where a number of previous studies have reported El Niño-Southern Oscillation (ENSO) as the main driver of climate variability. Supervised machine learning algorithms were trained with customized and bias-corrected predictors from NCEP reanalysis, and a cross-validation approach was implemented to assess both predictive skill and model selection. We found weak and not significant teleconnections between precipitation and lagged seasonal surface temperatures over El Niño3.4 domain, which suggests that ENSO fails to explain MAM rainfall variability in the study region. In contrast, series of Sea Level Pressure (SLP) over American Samoa -likely associated with the South Pacific Convergence Zone (SPCZ)- explains more than 65% of the precipitation variance. The best prediction skill was obtained with Selected Generalized Additive Models (SGAM) given their ability to capture linear/nonlinear relationships present in the data. While SPCZ-related series exhibited a positive linear effect in the rainfall response, SLP predictors in the north Atlantic and central equatorial Pacific showed nonlinear effects. A multimodel (MIROC, CanESM2 and CCSM) ensemble of ESD projections revealed

  11. A comparative study of large-scale atmospheric circulation in the context of a future scenario (RCP4.5 and past warmth (mid-Pliocene

    Directory of Open Access Journals (Sweden)

    Y. Sun

    2013-07-01

    Full Text Available The mid-Pliocene warm period (~ 3.3–3.0 Ma is often considered as the last sustained warm period with close enough geographic configurations compared to the present one associated with atmospheric CO2 concentration (405 ± 50 ppm higher than the modern level. For this reason, this period is often considered as a potential analogue for the future climate warming, with the important advantage that for mid-Pliocene many marine and continental data are available. To investigate this issue, we selected the RCP4.5 scenario, one of the current available future projections, to compare the pattern of tropical atmospheric response with the past warm mid-Pliocene climate. We use three Atmosphere-Ocean General Circulation Model (AOGCM simulations (RCP4.5 scenario, mid-Pliocene and present-day simulation carried out with the IPSL-CM5A model and investigate atmospheric tropical dynamics through Hadley and Walker cell responses to warmer conditions, considering that the analysis can provide some assessment of how these circulations will change in the future. Our results show that there is a damping of the Hadley cell intensity in the northern tropics and an increase in both subtropics. Moreover, northern and southern Hadley cells expand poleward. The response of the Hadley cells is stronger for the RCP4.5 scenario than for the mid-Pliocene, but in very good agreement with the fact that the atmospheric CO2 concentration is higher in the future scenario than in the mid-Pliocene (543 versus 405 ppm. Concerning the response of the Walker cell, we show that despite very large similarities, there are also some differences. Common features to both scenarios are: weakening of the ascending branch, leading to a suppression of the precipitation over the western tropical Pacific. The response of the Walker cell is stronger in the RCP4.5 scenario than in the mid-Pliocene but also depicts some major differences, as an eastward shift of its rising branch in the future

  12. The LMDZ4 general circulation model: climate performance and sensitivity to parametrized physics with emphasis on tropical convection

    Energy Technology Data Exchange (ETDEWEB)

    Hourdin, Frederic; Musat, Ionela; Bony, Sandrine; Codron, Francis; Dufresne, Jean-Louis; Fairhead, Laurent; Grandpeix, Jean-Yves; LeVan, Phu; Li, Zhao-Xin; Lott, Francois [CNRS/UPMC, Laboratoire de Meteorologie Dynamique (LMD/IPSL), Paris Cedex 05 (France); Braconnot, Pascale; Friedlingstein, Pierre [Laboratoire des Sciences du Climat et de l' Environnement (LSCE/IPSL), Saclay (France); Filiberti, Marie-Angele [Institut Pierre Simon Laplace (IPSL), Paris (France); Krinner, Gerhard [Laboratoire de Glaciologie et Geophysique de l' Environnement, Grenoble (France)

    2006-12-15

    The LMDZ4 general circulation model is the atmospheric component of the IPSL-CM4 coupled model which has been used to perform climate change simulations for the 4th IPCC assessment report. The main aspects of the model climatology (forced by observed sea surface temperature) are documented here, as well as the major improvements with respect to the previous versions, which mainly come form the parametrization of tropical convection. A methodology is proposed to help analyse the sensitivity of the tropical Hadley-Walker circulation to the parametrization of cumulus convection and clouds. The tropical circulation is characterized using scalar potentials associated with the horizontal wind and horizontal transport of geopotential (the Laplacian of which is proportional to the total vertical momentum in the atmospheric column). The effect of parametrized physics is analysed in a regime sorted framework using the vertical velocity at 500 hPa as a proxy for large scale vertical motion. Compared to Tiedtke's convection scheme, used in previous versions, the Emanuel's scheme improves the representation of the Hadley-Walker circulation, with a relatively stronger and deeper large scale vertical ascent over tropical continents, and suppresses the marked patterns of concentrated rainfall over oceans. Thanks to the regime sorted analyses, these differences are attributed to intrinsic differences in the vertical distribution of convective heating, and to the lack of self-inhibition by precipitating downdraughts in Tiedtke's parametrization. Both the convection and cloud schemes are shown to control the relative importance of large scale convection over land and ocean, an important point for the behaviour of the coupled model. (orig.)

  13. The Vertical Structure of Relative Humidity and Ozone in the Tropical Upper Troposphere: Intercomparisons Among In Situ Observations, A-Train Measurements and Large-Scale Models

    Science.gov (United States)

    Selkirk, Henry B.; Manyin, Michael; Douglass, Anne R.; Oman, Luke; Pawson, Steven; Ott, Lesley; Benson, Craig; Stolarski, Richard

    2010-01-01

    In situ measurements in the tropics have shown that in regions of active convection, relative humidity with respect to ice in the upper troposphere is typically close to saturation on average, and supersaturations greater than 20% are not uncommon. Balloon soundings with the cryogenic frost point hygrometer (CFH) at Costa Rica during northern summer, for example, show this tendency to be strongest between 11 and 15.5 km (345-360 K potential temperature, or approximately 250-120 hPa). this is the altitude range of deep convective detrainment. Additionally, simultaneous ozonesonde measurements show that stratospheric air (O3 greater than 150 ppbv) can be found as low as approximately 14 km (350 K/150 hPa). In contrast, results from northern winter show a much drier upper troposphere and little penetration of stratospheric air below the tropopause at 17.5 km (approximately 383 K). We show that these results are consistent with in situ measurements from the Measurement of Ozone and water vapor by Airbus In-service airCraft (MOZAIC) program which samples a wider, though still limited, range of tropical locations. To generalize to the tropics as a whole, we compare our insitu results to data from two A-Train satellite instruments, the Atmospheric Infrared Sounder (AIRS) and the Microwave Limb Sounder (MLS) on the Aqua and Aura satellites respectively. Finally, we examine the vertical structure of water vapor, relative humidity and ozone in the NASA Goddard MERRA analysis, an assimilation dataset, and a new version of the GEOS CCM, a free-running chemistry-climate model. We demonstrate that conditional probability distributions of relative humidity and ozone are a sensitive diagnostic for assessing the representation of deep convection and upper troposphere/lower stratosphere mixing processes in large-scale analyses and climate models.

  14. Present and future connection of Asian-Pacific Oscillation to large-scale atmospheric circulations and East Asian rainfall: results of CMIP5

    Science.gov (United States)

    Zhou, Botao; Xu, Ying; Shi, Ying

    2018-01-01

    The summer Asian-Pacific oscillation (APO), one of the major modes of climate variability over the Asian-Pacific sector, has a pronounced effect on variations of large-scale atmospheric circulations and climate. This study evaluated the capability of 30 state-of-the-art climate models among the Coupled Model Intercomparison Project Phase 5 (CMIP5) in simulating its association with the atmospheric circulations over the Asian-Pacific region and the precipitation over East Asia. Furthermore, their future connections under the RCP8.5 scenario were examined. The evaluation results show that 5 out of 30 climate models can well capture the observed APO-related features in a comprehensive way, including the strengthened South Asian high (SAH), deepened North Pacific trough (NPT) and northward East Asian jet (EAJ) in the upper troposphere; an intensification of the Asian low and the North Pacific subtropical high (NPSH) as well as a northward shift of the western Pacific subtropical high (WPSH) in the lower troposphere; and a decrease in East Asian summer rainfall (EASR) under the positive APO phase. Based on the five CMIP5 models' simulations, the dynamic linkages of the APO to the SAH, NPT, AL, and NPSH are projected to maintain during the second half of the twenty-first century. However, its connection with the EASR tends to reduce significantly. Such a reduction might result from the weakening of the linkage of the APO to the meridional displacement of the EAJ and WPSH as a response to the warming scenario.

  15. Impact of Tropical Volcanic Eruptions on Hadley Circulation Using a High-Resolution AGCM

    KAUST Repository

    Dogar, Muhammad Mubashar

    2018-03-31

    The direct radiative effects of volcanic eruptions resulting in solar dimming, stratospheric warming, global surface cooling and reduction in rainfall are well documented. However, eruptions also cause indirect climatic impacts that are not well understood. For example, solar dimming induced by volcanic aerosols could cause changes in tropical Hadley circulation that in turn largely affect evaporation and precipitation patterns. Therefore, understanding the sensitivity of HC to volcanism is essential, as this circulation is directly related to precipitation changes in the tropics and with other large-scale circulations. Hence, to better understand the post-eruption sensitivity of HC and associated changes in the hydrologic cycle, simulations for the El Chichón and Pinatubo tropical eruptions were conducted using a high-resolution atmospheric model (HIRAM), effectively at 25 and 50 km grid spacing. The model simulated results are then compared with observational and reanalysis products. Both the model and observational analysis show posteruption weakening, shrinking and equatorward displacement of the updraft branch of HC caused by the equatorward shift of midlatitude jets and hemispheric land-sea thermal gradient. The Intertropical Convergence Zone (ITCZ) is tightly coupled to the rising branch of HC, hence, post-eruption weakening and equatorward displacement of HC cause weakening of ITCZ that adversely affects rainfall distribution in the monsoon-fed regions, especially the South Asian and African tropical rain-belt regions. The modelproduced post-eruption distribution of cloud contents suggests a southward shift of ITCZ. The HIRAM results are largely in agreement with the reanalysis, observations and previous studies indicating that this model performs reasonably well in reproducing the global and regional-scale dynamic changes caused by volcanic radiative forcing.

  16. Impact of Tropical Volcanic Eruptions on Hadley Circulation Using a High-Resolution AGCM

    KAUST Repository

    Dogar, Muhammad Mubashar

    2018-01-01

    The direct radiative effects of volcanic eruptions resulting in solar dimming, stratospheric warming, global surface cooling and reduction in rainfall are well documented. However, eruptions also cause indirect climatic impacts that are not well understood. For example, solar dimming induced by volcanic aerosols could cause changes in tropical Hadley circulation that in turn largely affect evaporation and precipitation patterns. Therefore, understanding the sensitivity of HC to volcanism is essential, as this circulation is directly related to precipitation changes in the tropics and with other large-scale circulations. Hence, to better understand the post-eruption sensitivity of HC and associated changes in the hydrologic cycle, simulations for the El Chichón and Pinatubo tropical eruptions were conducted using a high-resolution atmospheric model (HIRAM), effectively at 25 and 50 km grid spacing. The model simulated results are then compared with observational and reanalysis products. Both the model and observational analysis show posteruption weakening, shrinking and equatorward displacement of the updraft branch of HC caused by the equatorward shift of midlatitude jets and hemispheric land-sea thermal gradient. The Intertropical Convergence Zone (ITCZ) is tightly coupled to the rising branch of HC, hence, post-eruption weakening and equatorward displacement of HC cause weakening of ITCZ that adversely affects rainfall distribution in the monsoon-fed regions, especially the South Asian and African tropical rain-belt regions. The modelproduced post-eruption distribution of cloud contents suggests a southward shift of ITCZ. The HIRAM results are largely in agreement with the reanalysis, observations and previous studies indicating that this model performs reasonably well in reproducing the global and regional-scale dynamic changes caused by volcanic radiative forcing.

  17. Large-scale carbon stock assessment of woody vegetation in tropical dry deciduous forest of Sathanur reserve forest, Eastern Ghats, India.

    Science.gov (United States)

    Gandhi, Durai Sanjay; Sundarapandian, Somaiah

    2017-04-01

    Tropical dry forests are one of the most widely distributed ecosystems in tropics, which remain neglected in research, especially in the Eastern Ghats. Therefore, the present study was aimed to quantify the carbon storage in woody vegetation (trees and lianas) on large scale (30, 1 ha plots) in the dry deciduous forest of Sathanur reserve forest of Eastern Ghats. Biomass of adult (≥10 cm DBH) trees was estimated by species-specific allometric equations using diameter and wood density of species whereas in juvenile tree population and lianas, their respective general allometric equations were used to estimate the biomass. The fractional value 0.4453 was used to convert dry biomass into carbon in woody vegetation of tropical dry forest. The mean aboveground biomass value of juvenile tree population was 1.86 Mg/ha. The aboveground biomass of adult trees ranged from 64.81 to 624.96 Mg/ha with a mean of 245.90 Mg/ha. The mean aboveground biomass value of lianas was 7.98 Mg/ha. The total biomass of woody vegetation (adult trees + juvenile population of trees + lianas) ranged from 85.02 to 723.46 Mg/ha, with a mean value of 295.04 Mg/ha. Total carbon accumulated in woody vegetation in tropical dry deciduous forest ranged from 37.86 to 322.16 Mg/ha with a mean value of 131.38 Mg/ha. Adult trees accumulated 94.81% of woody biomass carbon followed by lianas (3.99%) and juvenile population of trees (1.20%). Albizia amara has the greatest biomass and carbon stock (58.31%) among trees except for two plots (24 and 25) where Chloroxylon swietenia contributed more to biomass and carbon stock. Similarly, Albizia amara (52.4%) showed greater carbon storage in juvenile population of trees followed by Chloroxylon swietenia (21.9%). Pterolobium hexapetalum (38.86%) showed a greater accumulation of carbon in liana species followed by Combretum albidum (33.04%). Even though, all the study plots are located within 10 km radius, they show a significant spatial variation among

  18. Responses of Cloud Type Distributions to the Large-Scale Dynamical Circulation: Water Budget-Related Dynamical Phase Space and Dynamical Regimes

    Science.gov (United States)

    Wong, Sun; Del Genio, Anthony; Wang, Tao; Kahn, Brian; Fetzer, Eric J.; L'Ecuyer, Tristan S.

    2015-01-01

    Goals: Water budget-related dynamical phase space; Connect large-scale dynamical conditions to atmospheric water budget (including precipitation); Connect atmospheric water budget to cloud type distributions.

  19. A revised method of presenting wavenumber-frequency power spectrum diagrams that reveals the asymmetric nature of tropical large-scale waves

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Winston C. [NASA/Goddard Space Flight Center, Global Modeling and Assimilation Office, Mail Code 610.1, Greenbelt, MD (United States); Yang, Bo; Fu, Xiouhua [University of Hawaii at Manoa, School of Ocean and Earth Science and Technology, International Pacific Research Center, Honolulu, HI (United States)

    2009-11-15

    The popular method of presenting wavenumber-frequency power spectrum diagrams for studying tropical large-scale waves in the literature is shown to give an incomplete presentation of these waves. The so-called ''convectively coupled Kelvin (mixed Rossby-gravity) waves'' are presented as existing only in the symmetric (anti-symmetric) component of the diagrams. This is obviously not consistent with the published composite/regression studies of ''convectively coupled Kelvin waves,'' which illustrate the asymmetric nature of these waves. The cause of this inconsistency is revealed in this note and a revised method of presenting the power spectrum diagrams is proposed. When this revised method is used, ''convectively coupled Kelvin waves'' do show anti-symmetric components, and ''convectively coupled mixed Rossby-gravity waves (also known as Yanai waves)'' do show a hint of symmetric components. These results bolster a published proposal that these waves should be called ''chimeric Kelvin waves,'' ''chimeric mixed Rossby-gravity waves,'' etc. This revised method of presenting power spectrum diagrams offers an additional means of comparing the GCM output with observations by calling attention to the capability of GCMs to correctly simulate the asymmetric characteristics of equatorial waves. (orig.)

  20. Variations in large-scale tropical cyclone genesis factors over the western North Pacific in the PMIP3 last millennium simulations

    Science.gov (United States)

    Yan, Qing; Wei, Ting; Zhang, Zhongshi

    2017-02-01

    Investigation of past tropical cyclone (TC) activity in the Western North Pacific (WNP) is potentially helpful to enable better understanding of future TC behaviors. In this study, we examine variations in large-scale environmental factors important to TC genesis in the last millennium simulations from the Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3). The results show that potential intensity, a theoretical prediction of the maximum TC intensity, is increased relative to the last millennium in the north part of the WNP in the Medieval Climate Anomaly (MCA; 950-1200 AD) while it is decreased in the Little Ice Age (LIA; 1600-1850 AD). Vertical wind shear that generally inhibits TC genesis is enhanced (reduced) to the south of 20°N and is reduced (enhanced) to the north in the MCA (LIA). Relative humidity (at 600 hPa) that measures the mid-tropospheric moisture content broadly shows an increase (decrease) in the MCA (LIA). A genesis potential index indicates that conditions are generally favorable (unfavorable) for TC formation in the WNP in the MCA (LIA), especially in the northern part. Taking changes in steering flows into account, there may be an increasing (decreasing) favorability for storm strikes in East Asia in the MCA (LIA). The estimated TC activity is consistent with the geological proxies in Japan, but contradicts with the typhoon records in southern China and Taiwan. This model-data discrepancy is attributed to the limitations in both simulations and reconstructions.

  1. Time-scale and extent at which large-scale circulation modes determine the wind and solar potential in the Iberian Peninsula

    International Nuclear Information System (INIS)

    Jerez, Sonia; Trigo, Ricardo M

    2013-01-01

    The North Atlantic Oscillation (NAO), the East Atlantic (EA) and the Scandinavian (SCAND) modes are the three main large-scale circulation patterns driving the climate variability of the Iberian Peninsula. This study assesses their influence in terms of solar (photovoltaic) and wind power generation potential (SP and WP) and evaluates their skill as predictors. For that we use a hindcast regional climate simulation to retrieve the primary meteorological variables involved, surface solar radiation and wind speed. First we identify that the maximum influence of the various modes occurs on the interannual variations of the monthly mean SP and WP series, being generally more relevant in winter. Second we find that in this time-scale and season, SP (WP) varies up to 30% (40%) with respect to the mean climatology between years with opposite phases of the modes, although the strength and the spatial distribution of the signals differ from one month to another. Last, the skill of a multi-linear regression model (MLRM), built using the NAO, EA and SCAND indices, to reconstruct the original wintertime monthly series of SP and WP was investigated. The reconstructed series (when the MLRM is calibrated for each month individually) correlate with the original ones up to 0.8 at the interannual time-scale. Besides, when the modeled series for each individual month are merged to construct an October-to-March monthly series, and after removing the annual cycle in order to account for monthly anomalies, these correlate 0.65 (0.55) with the original SP (WP) series in average. These values remain fairly stable when the calibration and reconstruction periods differ, thus supporting up to a point the predictive potential of the method at the time-scale assessed here. (letter)

  2. Coupling of latent heat flux and the greenhouse effect by large-scale tropical/subtropical dynamics diagnosed in a set of observations and model simulations

    Energy Technology Data Exchange (ETDEWEB)

    Gershunov, A. [Climate Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0224 (United States); Roca, R. [Laboratoire de Meteorologie Dynamique, Ecole Polytechnique, 91128 Palaiseau (France)

    2004-03-01

    Coupled variability of the greenhouse effect (GH) and latent heat flux (LHF) over the tropical - subtropical oceans is described, summarized and compared in observations and a coupled ocean-atmosphere general circulation model (CGCM). Coupled seasonal and interannual modes account for much of the total variability in both GH and LHF. In both observations and model, seasonal coupled variability is locally 180 out-of-phase throughout the tropics. Moisture is brought into convergent/convective regions from remote source areas located partly in the opposite, non-convective hemisphere. On interannual time scales, the tropical Pacific GH in the ENSO region of largest interannual variance is 180 out of phase with local LHF in observations but in phase in the model. A local source of moisture is thus present in the model on interannual time scales while in observations, moisture is mostly advected from remote source regions. The latent cooling and radiative heating of the surface as manifested in the interplay of LHF and GH is an important determinant of the current climate. Moreover, the hydrodynamic processes involved in the GH-LHF interplay determine in large part the climate response to external perturbations mainly through influencing the water vapor feedback but also through their intimate connection to the hydrological cycle. The diagnostic process proposed here can be performed on other CGCMs. Similarly, it should be repeated using a number of observational latent heat flux datasets to account for the variability in the different satellite retrievals. A realistic CGCM could be used to further study these coupled dynamics in natural and anthropogenically altered climate conditions. (orig.)

  3. Contributions of Heterogeneous Ice Nucleation, Large-Scale Circulation, and Shallow Cumulus Detrainment to Cloud Phase Transition in Mixed-Phase Clouds with NCAR CAM5

    Science.gov (United States)

    Liu, X.; Wang, Y.; Zhang, D.; Wang, Z.

    2016-12-01

    representations of large-scale moisture transport, cloud microphysics, ice nucleation, and cumulus detrainment in order to improve the mixed-phase transition in GCMs.

  4. Large scale electrolysers

    International Nuclear Information System (INIS)

    B Bello; M Junker

    2006-01-01

    Hydrogen production by water electrolysis represents nearly 4 % of the world hydrogen production. Future development of hydrogen vehicles will require large quantities of hydrogen. Installation of large scale hydrogen production plants will be needed. In this context, development of low cost large scale electrolysers that could use 'clean power' seems necessary. ALPHEA HYDROGEN, an European network and center of expertise on hydrogen and fuel cells, has performed for its members a study in 2005 to evaluate the potential of large scale electrolysers to produce hydrogen in the future. The different electrolysis technologies were compared. Then, a state of art of the electrolysis modules currently available was made. A review of the large scale electrolysis plants that have been installed in the world was also realized. The main projects related to large scale electrolysis were also listed. Economy of large scale electrolysers has been discussed. The influence of energy prices on the hydrogen production cost by large scale electrolysis was evaluated. (authors)

  5. Variability in Global-Scale Circulations and Their Impacts on Atlantic Tropical Cyclone Activity

    National Research Council Canada - National Science Library

    Rosencrans, Matthew J

    2006-01-01

    ... favorable or unfavorable for tropical cyclone formation. Favorable impacts on tropical Atlantic circulation characteristics are defined by an increase in low-level relative vorticity, a decrease in westerly vertical wind shear, and increased convection...

  6. Quantification of climatic feedbacks on the Caspian Sea level variability and impacts from the Caspian Sea on the large-scale atmospheric circulation

    Science.gov (United States)

    Arpe, Klaus; Tsuang, Ben-Jei; Tseng, Yu-Heng; Liu, Xin-Yu; Leroy, Suzanne A. G.

    2018-05-01

    the water budget of the whole catchment area due to feedbacks with the precipitation. This suggests a high proportion of recycling of water within the CS catchment area. When using a model which does not have a correct CS size, the effect of a reduced CS area on the water budget for the whole CS catchment can be estimated by taking the evaporation over the sea multiplied by the proportional changed area. However, only 50% of that change is ending up in the water balance of the total catchment of the CS. A formula is provided. This method has been applied to estimate the CSL during the Last Glacial Maximum to be at - 30 to - 33 m. The experiments show as well that the CS has an impact on the large-scale atmospheric circulation with a widened Aleutian 500 hPa height field trough with increasing CS sizes. It is possible to validate this aspect with observational data.

  7. Orographic effects on tropical climate in a coupled ocean-atmosphere general circulation model

    Science.gov (United States)

    Okajima, Hideki

    Large-scale mountain modifies the atmospheric circulation directly through dynamic and thermodynamic process, and also indirectly through the interaction with the ocean. To investigate orographic impacts on tropical climate, a fully coupled general circulation model (CGCM) is developed by coupling a state-of-the-art atmospheric general circulation model and an ocean general circulation model. With realistic boundary conditions, the CGCM produces a reasonable climatology of sea surface temperature (SST), surface winds, and precipitation. When global mountains are removed, the model climatology displays substantial changes in both the mean-state and the seasonal cycle. The equatorial eastern Pacific SST acquires a semi-annual component as inter-tropical convergence zone (ITCZ) flips and flops across the equator following the seasonal migration of the sun. Without the Andes, wet air flows into the southeastern tropical Pacific from the humid Amazon, which weakens the meridional asymmetry during the Peruvian warm season (February-April). In addition, the northeasterly trade winds are enhanced north of the equator without the orographic blocking of Central American mountains and cools SST. Triggered by the SST cooling north and moistening south of the equator, the wind-evaporation-SST (WES) feedback further weakens the meridional asymmetry and prolongs the southern ITCZ. In the Atlantic Ocean, the equatorial cold tongue is substantially strengthened and develops a pronounced annual cycle in the absence of mountains. The easterly winds are overall enhanced over the equatorial Atlantic without orographic heating over the African highlands, developing a zonal asymmetry strengthened by the Bjerknes feedback. In the Indian Ocean, the thermocline shoals eastward and an equatorial cold tongue appears twice a year. During boreal summer, the Findlater jet is greatly weakened off Somalia and SST warms in the western Indian Ocean, forcing the equatorial easterly winds amplified

  8. Interannual Weakening of the Tropical Pacific Walker Circulation Due to Strong Tropical Volcanism

    Science.gov (United States)

    Miao, Jiapeng; Wang, Tao; Wang, Huijun; Sun, Jianqi

    2018-06-01

    In order to examine the response of the tropical Pacific Walker circulation (PWC) to strong tropical volcanic eruptions (SVEs), we analyzed a three-member long-term simulation performed with HadCM3, and carried out four additional CAM4 experiments. We found that the PWC shows a significant interannual weakening after SVEs. The cooling effect from SVEs is able to cool the entire tropics. However, cooling over the Maritime Continent is stronger than that over the central-eastern tropical Pacific. Thus, non-uniform zonal temperature anomalies can be seen following SVEs. As a result, the sea level pressure gradient between the tropical Pacific and the Maritime Continent is reduced, which weakens trade winds over the tropical Pacific. Therefore, the PWC is weakened during this period. At the same time, due to the cooling subtropical and midlatitude Pacific, the Intertropical Convergence Zone (ITCZ) and South Pacific convergence zone (SPCZ) are weakened and shift to the equator. These changes also contribute to the weakened PWC. Meanwhile, through the positive Bjerknes feedback, weakened trade winds cause El Niño-like SST anomalies over the tropical Pacific, which in turn further influence the PWC. Therefore, the PWC significantly weakens after SVEs. The CAM4 experiments further confirm the influences from surface cooling over the Maritime Continent and subtropical/midlatitude Pacific on the PWC. Moreover, they indicate that the stronger cooling over the Maritime Continent plays a dominant role in weakening the PWC after SVEs. In the observations, a weakened PWC and a related El Niño-like SST pattern can be found following SVEs.

  9. Boundary layer circulation in disk-halo galaxies. III. The dispersion relation for local disturbances and large-scale spiral waves

    International Nuclear Information System (INIS)

    Waxman, A.M.

    1980-01-01

    This paper concerns the geometry and physical properties of waves which arise from a shear-flow (i.e. inflection point) instability of the galactic boundary layer circulation. This circulation was shown to exist in the meridional plane of a model galaxy containing a gaseous disk embedded in a rotating gaseous halo. Previously derived equations describe the local effects of Boussinesq perturbations, in the form of spiral waves with aribitrary pitch angle, on the model disk-halo system. The equations are solved asymptotically for large values of the local Reynolds number. In passing to the limit of inviscid waves, it is possible to derive a locally valid dispersion relation. A perturbation technique is developed whereby the inviscid wave eigenvalues can be corrected for the effects of small but finite viscosity. In this way the roles of the buoyancy force, Coriolis acceleration, viscous stresses, and their interactions can be studied. It is found that, locally, the most unstable inviscid waves are leading and open with large azimuthal wavenumbers. However, these waves display little or no coherence over the face of the disk and so would not emerge as modes in a global analysis.The geometry of the dominant inviscid waves is found to be leading, tightly wound spirals. Viscous corrections shift the dominant wave form to trailing, tightly wound spirals with small azimuthal wavenumbers. These waves grow on a time scale of about 10 7 years. It is suggested that these waves can initiate spiral structure in galaxies during disk formation and that a subsequent transition to a self-gravitating acoustical mode with the same spiral geometry may occur. This transition becomes possible once the contrast in gas densities between the disk and surrounding halo becomes sufficiently large

  10. Direct weakening of tropical circulations from masked CO2 radiative forcing.

    Science.gov (United States)

    Merlis, Timothy M

    2015-10-27

    Climate models robustly simulate weakened mean circulations of the tropical atmosphere in direct response to increased carbon dioxide (CO2). The direct response to CO2, defined by the response to radiative forcing in the absence of changes in sea surface temperature, affects tropical precipitation and tropical cyclone genesis, and these changes have been tied to the weakening of the mean tropical circulation. The mechanism underlying this direct CO2-forced circulation change has not been elucidated. Here, I demonstrate that this circulation weakening results from spatial structure in CO2's radiative forcing. In regions of ascending circulation, such as the intertropical convergence zone, the CO2 radiative forcing is reduced, or "masked," by deep-convective clouds and high humidity; in subsiding regions, such as the subtropics, the CO2 radiative forcing is larger because the atmosphere is drier and deep-convective clouds are infrequent. The spatial structure of the radiative forcing reduces the need for the atmosphere to transport energy. This, in turn, weakens the mass overturning of the tropical circulation. The previously unidentified mechanism is demonstrated in a hierarchy of atmospheric general circulation model simulations with altered radiative transfer to suppress the cloud masking of the radiative forcing. The mechanism depends on the climatological distribution of clouds and humidity, rather than uncertain changes in these quantities. Masked radiative forcing thereby offers an explanation for the robustness of the direct circulation weakening under increased CO2.

  11. On the semi-diagnostic computation of climatological circulation in the western tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shaji, C.; Rao, A.D.; Dube, S.K.; Bahulayan, N.

    and internal density field on the dynamical balance of circulation in the western tropical Indian Ocean is explained. The climatological temperature and salinity data used to drive the model is found to be hydrodynamically adjusted with surface wind, flow field...

  12. Large scale reflood test

    International Nuclear Information System (INIS)

    Hirano, Kemmei; Murao, Yoshio

    1980-01-01

    The large-scale reflood test with a view to ensuring the safety of light water reactors was started in fiscal 1976 based on the special account act for power source development promotion measures by the entrustment from the Science and Technology Agency. Thereafter, to establish the safety of PWRs in loss-of-coolant accidents by joint international efforts, the Japan-West Germany-U.S. research cooperation program was started in April, 1980. Thereupon, the large-scale reflood test is now included in this program. It consists of two tests using a cylindrical core testing apparatus for examining the overall system effect and a plate core testing apparatus for testing individual effects. Each apparatus is composed of the mock-ups of pressure vessel, primary loop, containment vessel and ECCS. The testing method, the test results and the research cooperation program are described. (J.P.N.)

  13. Development and Implementation of 3-D, High Speed Capacitance Tomography for Imaging Large-Scale, Cold-Flow Circulating Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Marashdeh, Qussai [Tech4imaging LLC, Columbus, OH (United States)

    2013-02-01

    A detailed understanding of multiphase flow behavior inside a Circulating Fluidized Bed (CFB) requires a 3-D technique capable of visualizing the flow field in real-time. Electrical Capacitance Volume Tomography (ECVT) is a newly developed technique that can provide such measurements. The attractiveness of the technique is in its low profile sensors, fast imaging speed and scalability to different section sizes, low operating cost, and safety. Moreover, the flexibility of ECVT sensors enable them to be designed around virtually any geometry, rendering them suitable to be used for measurement of solid flows in exit regions of the CFB. Tech4Imaging LLC has worked under contract with the U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) to develop an ECVT system for cold flow visualization and install it on a 12 inch ID circulating fluidized bed. The objective of this project was to help advance multi-phase flow science through implementation of an ECVT system on a cold flow model at DOE NETL. This project has responded to multi-phase community and industry needs of developing a tool that can be used to develop flow models, validate computational fluid dynamics simulations, provide detailed real-time feedback of process variables, and provide a comprehensive understating of multi-phase flow behavior. In this project, a complete ECVT system was successfully developed after considering different potential electronics and sensor designs. The system was tested at various flow conditions and with different materials, yielding real-time images of flow interaction in a gas-solid flow system. The system was installed on a 12 inch ID CFB of the US Department of Energy, Morgantown Labs. Technical and economic assessment of Scale-up and Commercialization of ECVT was also conducted. Experiments conducted with larger sensors in conditions similar to industrial settings are very promising. ECVT has also the potential to be developed for imaging multi

  14. The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests.

    Science.gov (United States)

    Salinas, N; Malhi, Y; Meir, P; Silman, M; Roman Cuesta, R; Huaman, J; Salinas, D; Huaman, V; Gibaja, A; Mamani, M; Farfan, F

    2011-03-01

    • We present the results from a litter translocation experiment along a 2800-m elevation gradient in Peruvian tropical forests. The understanding of the environmental factors controlling litter decomposition is important in the description of the carbon and nutrient cycles of tropical ecosystems, and in predicting their response to long-term increases in temperature. • Samples of litter from 15 species were transplanted across all five sites in the study, and decomposition was tracked over 448 d. • Species' type had a large influence on the decomposition rate (k), most probably through its influence on leaf quality and morphology. When samples were pooled across species and elevations, soil temperature explained 95% of the variation in the decomposition rate, but no direct relationship was observed with either soil moisture or rainfall. The sensitivity of the decay rate to temperature (κ(T)) varied seven-fold across species, between 0.024 and 0.169 °C⁻¹, with a mean value of 0.118 ± 0.009 °C⁻¹ (SE). This is equivalent to a temperature sensitivity parameter (Q₁₀) for litter decay of 3.06 ± 0.28, higher than that frequently assumed for heterotrophic processes. • Our results suggest that the warming of approx. 0.9 °C experienced in the region in recent decades may have increased decomposition and nutrient mineralization rates by c. 10%. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

  15. Large-scale river regulation

    International Nuclear Information System (INIS)

    Petts, G.

    1994-01-01

    Recent concern over human impacts on the environment has tended to focus on climatic change, desertification, destruction of tropical rain forests, and pollution. Yet large-scale water projects such as dams, reservoirs, and inter-basin transfers are among the most dramatic and extensive ways in which our environment has been, and continues to be, transformed by human action. Water running to the sea is perceived as a lost resource, floods are viewed as major hazards, and wetlands are seen as wastelands. River regulation, involving the redistribution of water in time and space, is a key concept in socio-economic development. To achieve water and food security, to develop drylands, and to prevent desertification and drought are primary aims for many countries. A second key concept is ecological sustainability. Yet the ecology of rivers and their floodplains is dependent on the natural hydrological regime, and its related biochemical and geomorphological dynamics. (Author)

  16. A degradation debt? Large-scale shifts in community composition and loss of biomass in a tropical forest fragment after 40 years of isolation.

    Science.gov (United States)

    Zahawi, Rakan A; Oviedo-Brenes, Federico; Peterson, Chris J

    2017-01-01

    Habitat loss and fragmentation are among the biggest threats to tropical biodiversity and associated ecosystem services. We examined forest dynamics in a mid-elevation 365-ha fragment in southern Costa Rica. The fragment was isolated in the mid-1970s and belongs to the Las Cruces Biological Station. A 2.25-ha permanent plot was established in the center of the old-growth forest (>400 m to nearest edge boundary) and all plants >5 cm DBH were censused, mapped, and identified to species in two surveys taken ~5-6 years apart (>3,000 stems/survey). Although the reserve maintains high species richness (>200 spp.), with many rare species represented by only one individual, we document a strong shift in composition with a two-fold increase in the number of soft-wooded pioneer individuals. The dominant late-successional understory tree species, Chrysochlamys glauca (Clusiaceae), and most species in the Lauraceae, declined dramatically. Turnover was high: 22.9% of stems in the first survey were lost, and 27.8% of stems in the second survey represented new recruits. Mean tree diameter decreased significantly and there was a 10% decrease in overall biomass. Such alteration has been documented previously but only in smaller fragments or within ~100 m of an edge boundary. Further penetration into this fragment was perhaps driven by a progressive invasion of disturbance-adapted species into the fragment's core over time; the loss of once-dominant late successional species could be a contributing factor. The pattern found is of particular concern given that such fragments represent a substantial portion of today's remaining tropical habitat; further studies in similar-sized fragments that have been isolated for similar prolonged periods are called for.

  17. A degradation debt? Large-scale shifts in community composition and loss of biomass in a tropical forest fragment after 40 years of isolation.

    Directory of Open Access Journals (Sweden)

    Rakan A Zahawi

    Full Text Available Habitat loss and fragmentation are among the biggest threats to tropical biodiversity and associated ecosystem services. We examined forest dynamics in a mid-elevation 365-ha fragment in southern Costa Rica. The fragment was isolated in the mid-1970s and belongs to the Las Cruces Biological Station. A 2.25-ha permanent plot was established in the center of the old-growth forest (>400 m to nearest edge boundary and all plants >5 cm DBH were censused, mapped, and identified to species in two surveys taken ~5-6 years apart (>3,000 stems/survey. Although the reserve maintains high species richness (>200 spp., with many rare species represented by only one individual, we document a strong shift in composition with a two-fold increase in the number of soft-wooded pioneer individuals. The dominant late-successional understory tree species, Chrysochlamys glauca (Clusiaceae, and most species in the Lauraceae, declined dramatically. Turnover was high: 22.9% of stems in the first survey were lost, and 27.8% of stems in the second survey represented new recruits. Mean tree diameter decreased significantly and there was a 10% decrease in overall biomass. Such alteration has been documented previously but only in smaller fragments or within ~100 m of an edge boundary. Further penetration into this fragment was perhaps driven by a progressive invasion of disturbance-adapted species into the fragment's core over time; the loss of once-dominant late successional species could be a contributing factor. The pattern found is of particular concern given that such fragments represent a substantial portion of today's remaining tropical habitat; further studies in similar-sized fragments that have been isolated for similar prolonged periods are called for.

  18. A large-scale solar greenhouse dryer using polycarbonate cover: Modeling and testing in a tropical environment of Lao People's Democratic Republic

    Energy Technology Data Exchange (ETDEWEB)

    Janjai, Serm; Intawee, Poolsak; Kaewkiew, Jinda; Sritus, Chanoke [Solar Energy Research Laboratory, Department of Physics, Faculty of Science, Silpakorn University, Nakhon Pathom 73000 (Thailand); Khamvongsa, Vathsana [Department of Physics, Faculty of Natural Science, National University of Laos, P O Box 7322, Vientiane (Lao People' s Democratic Republic)

    2011-03-15

    A large-scale solar greenhouse dryer with a loading capacity of 1000 kg of fruits or vegetables has been developed and tested at field levels. The dryer has a parabolic shape and the dryer is covered with polycarbonate sheets. The base of the dryer is a black concrete floor with an area of 7.5 x 20.0 m{sup 2}. Nine DC fans powered by three 50-W solar cell modules are used to ventilate the dryer. The dryer was installed at Champasak (15.13 N, 105.79 E) in Lao People's Democratic Republic (Lao PDR). It is routinely used to dry chilli, banana and coffee. To assess the experimental performances of the dryer, air temperature, air relative humidity and product moisture contents were measured. One thousand kilograms of banana with the initial moisture content of 68% (wb) was dried within 5 days, compared to 7 days required for natural sun drying with the same weather conditions. Also three hundred kilograms of chilli with the initial moisture content of 75% (wb) was dried within 3 days while the natural sun drying needed 5 days. Two hundred kilograms of coffee with the initial moisture content of 52% (wb) was dried within 2 days as compared to 4 days required for natural sun drying. The chilli, coffee and banana dried in this dryer were completely protected from insects, animals and rain. Furthermore, good quality of dried products was obtained. The payback period of the dryer is estimated to be 2.5 years. A system of partial differential equations describing heat and moisture transfer during drying of chilli, coffee and banana in the greenhouse dryer was developed. These equations were solved by using the finite different method. The simulated results agree well with the experimental data. This model can be used to provide the design data for this type of dryer in other locations. (author)

  19. Sensitivity experiments with an adaptation model of circulation of western tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Shaji, C.; Rao, A.D.; Dube, S.K.

    circulation at 10 m depth is controlled by both wind stress and sea surface topography. Circulation at 50 m depth is mainly controlled by thermohaline forcing and sea surface topography. The current speed in the western tropical Indian Ocean is of the order...

  20. Large-Scale Examination of Spatio-Temporal Patterns of Drifting Fish Aggregating Devices (dFADs) from Tropical Tuna Fisheries of the Indian and Atlantic Oceans.

    Science.gov (United States)

    Maufroy, Alexandra; Chassot, Emmanuel; Joo, Rocío; Kaplan, David Michael

    2015-01-01

    Since the 1990s, massive use of drifting Fish Aggregating Devices (dFADs) to aggregate tropical tunas has strongly modified global purse-seine fisheries. For the first time, a large data set of GPS positions from buoys deployed by French purse-seiners to monitor dFADs is analysed to provide information on spatio-temporal patterns of dFAD use in the Atlantic and Indian Oceans during 2007-2011. First, we select among four classification methods the model that best separates "at sea" from "on board" buoy positions. A random forest model had the best performance, both in terms of the rate of false "at sea" predictions and the amount of over-segmentation of "at sea" trajectories (i.e., artificial division of trajectories into multiple, shorter pieces due to misclassification). Performance is improved via post-processing removing unrealistically short "at sea" trajectories. Results derived from the selected model enable us to identify the main areas and seasons of dFAD deployment and the spatial extent of their drift. We find that dFADs drift at sea on average for 39.5 days, with time at sea being shorter and distance travelled longer in the Indian than in the Atlantic Ocean. 9.9% of all trajectories end with a beaching event, suggesting that 1,500-2,000 may be lost onshore each year, potentially impacting sensitive habitat areas, such as the coral reefs of the Maldives, the Chagos Archipelago, and the Seychelles.

  1. Large-Scale Examination of Spatio-Temporal Patterns of Drifting Fish Aggregating Devices (dFADs from Tropical Tuna Fisheries of the Indian and Atlantic Oceans.

    Directory of Open Access Journals (Sweden)

    Alexandra Maufroy

    Full Text Available Since the 1990s, massive use of drifting Fish Aggregating Devices (dFADs to aggregate tropical tunas has strongly modified global purse-seine fisheries. For the first time, a large data set of GPS positions from buoys deployed by French purse-seiners to monitor dFADs is analysed to provide information on spatio-temporal patterns of dFAD use in the Atlantic and Indian Oceans during 2007-2011. First, we select among four classification methods the model that best separates "at sea" from "on board" buoy positions. A random forest model had the best performance, both in terms of the rate of false "at sea" predictions and the amount of over-segmentation of "at sea" trajectories (i.e., artificial division of trajectories into multiple, shorter pieces due to misclassification. Performance is improved via post-processing removing unrealistically short "at sea" trajectories. Results derived from the selected model enable us to identify the main areas and seasons of dFAD deployment and the spatial extent of their drift. We find that dFADs drift at sea on average for 39.5 days, with time at sea being shorter and distance travelled longer in the Indian than in the Atlantic Ocean. 9.9% of all trajectories end with a beaching event, suggesting that 1,500-2,000 may be lost onshore each year, potentially impacting sensitive habitat areas, such as the coral reefs of the Maldives, the Chagos Archipelago, and the Seychelles.

  2. Circulation, eddies, oxygen, and nutrient changes in the eastern tropical South Pacific Ocean

    Science.gov (United States)

    Czeschel, R.; Stramma, L.; Weller, R. A.; Fischer, T.

    2015-06-01

    A large subsurface oxygen deficiency zone is located in the eastern tropical South Pacific Ocean (ETSP). The large-scale circulation in the eastern equatorial Pacific and off the coast of Peru in November/December 2012 shows the influence of the equatorial current system, the eastern boundary currents, and the northern reaches of the subtropical gyre. In November 2012 the equatorial undercurrent (EUC) is centered at 250 m depth, deeper than in earlier observations. In December 2012, the equatorial water is transported southeastward near the shelf in the Peru-Chile undercurrent (PCUC) with a mean transport of 1.4 Sv. In the oxygen minimum zone (OMZ), the flow is overlaid with strong eddy activity on the poleward side of the OMZ. Floats with parking depth at 400 m show fast westward flow in the mid-depth equatorial channel and sluggish flow in the OMZ. Floats with oxygen sensors clearly show the passage of eddies with oxygen anomalies. The long-term float observations in the upper ocean lead to a net community production estimate at about 18° S of up to 16.7 mmol C m-3 yr-1 extrapolated to an annual rate and 7.7 mmol C m-3 yr-1 for the time period below the mixed layer. Oxygen differences between repeated ship sections are influenced by the Interdecadal Pacific Oscillation (IPO), by the phase of El Niño, by seasonal changes, and by eddies, and hence have to be interpreted with care. At and south of the Equator the decrease in oxygen in the upper ocean since 1976 is related to an increase in nitrate, phosphate, and in part silicate.

  3. Large Scale Solar Heating

    DEFF Research Database (Denmark)

    Heller, Alfred

    2001-01-01

    The main objective of the research was to evaluate large-scale solar heating connected to district heating (CSDHP), to build up a simulation tool and to demonstrate the application of the simulation tool for design studies and on a local energy planning case. The evaluation was mainly carried out...... model is designed and validated on the Marstal case. Applying the Danish Reference Year, a design tool is presented. The simulation tool is used for proposals for application of alternative designs, including high-performance solar collector types (trough solar collectors, vaccum pipe collectors......). Simulation programs are proposed as control supporting tool for daily operation and performance prediction of central solar heating plants. Finaly the CSHP technolgy is put into persepctive with respect to alternatives and a short discussion on the barries and breakthrough of the technology are given....

  4. Large scale model testing

    International Nuclear Information System (INIS)

    Brumovsky, M.; Filip, R.; Polachova, H.; Stepanek, S.

    1989-01-01

    Fracture mechanics and fatigue calculations for WWER reactor pressure vessels were checked by large scale model testing performed using large testing machine ZZ 8000 (with a maximum load of 80 MN) at the SKODA WORKS. The results are described from testing the material resistance to fracture (non-ductile). The testing included the base materials and welded joints. The rated specimen thickness was 150 mm with defects of a depth between 15 and 100 mm. The results are also presented of nozzles of 850 mm inner diameter in a scale of 1:3; static, cyclic, and dynamic tests were performed without and with surface defects (15, 30 and 45 mm deep). During cyclic tests the crack growth rate in the elastic-plastic region was also determined. (author). 6 figs., 2 tabs., 5 refs

  5. Large scale tracking algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Ross L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Love, Joshua Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Melgaard, David Kennett [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Karelitz, David B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pitts, Todd Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zollweg, Joshua David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, Dylan Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nandy, Prabal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Whitlow, Gary L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bender, Daniel A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Byrne, Raymond Harry [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    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.

  6. Asymmetric variations in the tropical ascending branches of Hadley circulations and the associated mechanisms and effects

    Science.gov (United States)

    Sun, Bo

    2018-03-01

    This study investigates the variations in the tropical ascending branches (TABs) of Hadley circulations (HCs) during past decades, using a variety of reanalysis datasets. The northern tropical ascending branch (NTAB) and the southern tropical ascending branch (STAB), which are defined as the ascending branches of the Northern Hemisphere HC and Southern Hemisphere HC, respectively, are identified and analyzed regarding their trends and variability. The reanalysis datasets consistently show a persistent increase in STAB during past decades, whereas they show less consistency in NTAB regarding its decadalto multidecadal variability, which generally features a decreasing trend. These asymmetric trends in STAB and NTAB are attributed to asymmetric trends in the tropical SSTs. The relationship between STAB/NTAB and tropical SSTs is further examined regarding their interannual and decadal- to multidecadal variability. On the interannual time scale, the STAB and NTAB are essentially modulated by the eastern-Pacific type of ENSO, with a strengthened (weakened) STAB (NTAB) under an El Niño condition. On the decadal- to multidecadal time scale, the variability of STAB and NTAB is closely related to the southern tropical SSTs and the meridional asymmetry of global tropical SSTs, respectively. The tropical eastern Pacific SSTs (southern tropical SSTs) dominate the tropical SST-NTAB/STAB relationship on the interannual (decadal- to multidecadal) scale, whereas the NTAB is a passive factor in this relationship. Moreover, a cross-hemispheric relationship between the NTAB/STAB and the HC upper-level meridional winds is revealed.

  7. The impact of environmental inertial stability on the secondary circulation of axisymmetric tropical cyclones

    Science.gov (United States)

    O'Neill, M. E.; Chavas, D. R.

    2017-12-01

    In f-plane numerical simulations and analytical theory, tropical cyclones completely recycle their exhausted outflow air back into the boundary layer. This low-angular momentum air must experience cyclonic torque at the sea surface for cyclone to reach equilibrium. On Earth, however, it is not clear that tropical cyclones recycle all of the outflow air in a closed secondary circulation, and strong asymmetric outflow-jet interactions suggest that much of the air may be permanently evacuated from the storm over its lifetime. The fraction of outflow air that is returned to the near-storm boundary layer is in part a function of the environmental inertial stability, which controls the size and strength of the upper anticyclone. We run a suite of idealized axisymmetric tropical cyclone simulations at constant latitude while varying the outer domain's inertial stability profile. Fixing the latitude allows the gradient wind balance of the storm core to remain constant except for changes due to the far environment. By varying both the outer inertial stability and its location with respect to the Rossby radius of deformation, we show how the tropical cyclone's area-of-influence is controlled by the nature and strength of the upper anticyclone. Parcel tracking additionally demonstrates the likelihood of outflow air parcels to be quickly re-consumed by the secondary circulation as a function of inertial stability. These experiments demonstrate the sensitivity of the tropical cyclone's secondary circulation, typically assumed to be closed, to the dynamics of the far environment.

  8. Large-scale solar purchasing

    International Nuclear Information System (INIS)

    1999-01-01

    The principal objective of the project was to participate in the definition of a new IEA task concerning solar procurement (''the Task'') and to assess whether involvement in the task would be in the interest of the UK active solar heating industry. The project also aimed to assess the importance of large scale solar purchasing to UK active solar heating market development and to evaluate the level of interest in large scale solar purchasing amongst potential large scale purchasers (in particular housing associations and housing developers). A further aim of the project was to consider means of stimulating large scale active solar heating purchasing activity within the UK. (author)

  9. Understanding changes in water availability in the Rio Grande/Río Bravo del Norte basin under the influence of large-scale circulation indices using the Noah land surface model

    Science.gov (United States)

    Khedun, C. Prakash; Mishra, Ashok K.; Bolten, John D.; Beaudoing, Hiroko K.; Kaiser, Ronald A.; Giardino, J. Richard; Singh, Vijay P.

    2012-03-01

    Water availability plays an important role in the socio-economic development of a region. It is however, subject to the influence of large-scale circulation indices, resulting in periodic excesses and deficits. An assessment of the degree of correlation between climate indices and water availability, and the quantification of changes with respect to major climate events is important for long-term water resources planning and management, especially in transboundary basins as it can help in conflict avoidance. In this study we first establish the correlation of the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO) with gauged precipitation in the Rio Grande basin, and then quantify the changes in water availability using runoff generated from the Noah land surface model. Both spatial and temporal variations are noted, with winter and spring being most influenced by conditions in the Pacific Ocean. Negative correlation is observed at the headwaters and positive correlation across the rest of the basin. The influence of individual ENSO events, classified using four different criteria, is also examined. El Niños (La Niñas) generally cause an increase (decrease) in runoff, but the pattern is not consistent; percentage change in water availability varies across events. Further, positive PDO enhances the effect of El Niño and dampens that of La Niña, but during neutral/transitioning PDO, La Niña dominates meteorological conditions. Long El Niños have more influence on water availability than short duration high intensity events. We also note that the percentage increase during El Niños significantly offsets the drought-causing effect of La Niñas.

  10. Understanding Changes in Water Availability in the Rio Grande/Rio Bravo del Norte Basin Under the Influence of Large-Scale Circulation Indices Using the Noah Land Surface Model

    Science.gov (United States)

    Khedun, C. Prakash; Mishra, Ashok K.; Bolten, John D.; Beaudoing, Hiroko K.; Kaiser, Ronald A.; Giardino, J. Richard; Singh, Vijay P.

    2012-01-01

    Water availability plays an important role in the socio-economic development of a region. It is however, subject to the influence of large-scale circulation indices, resulting in periodic excesses and deficits. An assessment of the degree of correlation between climate indices and water availability, and the quantification of changes with respect to major climate events is important for long-term water resources planning and management, especially in transboundary basins as it can help in conflict avoidance. In this study we first establish the correlation of the Pacific Decadal Oscillation (PDO) and El Nino-Southern Oscillation (ENSO) with gauged precipitation in the Rio Grande basin, and quantify the changes in water availability using runoff generated from the Noah land surface model. Both spatial and temporal variations are noted, with winter and spring being most influenced by conditions in the Pacific Ocean. Negative correlation is observed at the headwaters and positive correlation across the rest of the basin. The influence of individual ENSO events, classified using four different criteria, is also examined. El Ninos (La Ninas) generally cause an increase (decrease) in runoff, but the pattern is not consistent; percentage change in water availability varies across events. Further, positive PDO enhances the effect of El Nino and dampens that of La Nina, but during neutral/transitioning PDO, La Nina dominates meteorological conditions. Long El Ninos have more influence on water availability than short duration high intensity events. We also note that the percentage increase during El Ninos significantly offsets the drought-causing effect of La Ninas.

  11. Large-scale data analytics

    CERN Document Server

    Gkoulalas-Divanis, Aris

    2014-01-01

    Provides cutting-edge research in large-scale data analytics from diverse scientific areas Surveys varied subject areas and reports on individual results of research in the field Shares many tips and insights into large-scale data analytics from authors and editors with long-term experience and specialization in the field

  12. Large-scale grid management

    International Nuclear Information System (INIS)

    Langdal, Bjoern Inge; Eggen, Arnt Ove

    2003-01-01

    The network companies in the Norwegian electricity industry now have to establish a large-scale network management, a concept essentially characterized by (1) broader focus (Broad Band, Multi Utility,...) and (2) bigger units with large networks and more customers. Research done by SINTEF Energy Research shows so far that the approaches within large-scale network management may be structured according to three main challenges: centralization, decentralization and out sourcing. The article is part of a planned series

  13. Polynomial Chaos–Based Bayesian Inference of K-Profile Parameterization in a General Circulation Model of the Tropical Pacific

    KAUST Repository

    Sraj, Ihab; Zedler, Sarah E.; Knio, Omar; Jackson, Charles S.; Hoteit, Ibrahim

    2016-01-01

    The authors present a polynomial chaos (PC)-based Bayesian inference method for quantifying the uncertainties of the K-profile parameterization (KPP) within the MIT general circulation model (MITgcm) of the tropical Pacific. The inference

  14. Intercomparison of the seasonal cycle of tropical surface stress in 17 AMIP atmospheric general circulation models

    Energy Technology Data Exchange (ETDEWEB)

    Saji, N.H.; Goswami, B.N. [Indian Inst. of Sci., Bangalore (India). Centre for Atmos. and Oceanic Sci.

    1997-08-01

    The mean state of the tropical atmosphere is important as the nature of the coupling between the ocean and the atmosphere depends nonlinearly on the basic state of the coupled system. The simulation of the annual cycle of the tropical surface wind stress by 17 atmospheric general circulation models (AGCMs) is examined and intercompared. The models considered were part of the atmospheric model intercomparison project (AMIP) and were integrated with observed sea surface temperature (SST) for the decade 1979-1988. Several measures have been devised to intercompare the performance of the 17 models on global tropical as well as regional scales. Within the limits of observational uncertainties, the models under examination simulate realistic tropical area-averaged zonal and meridional annual mean stresses. This is a noteworthy improvement over older generation low resolution models which were noted for their simulation of surface stresses considerably weaker than the observations. The models also simulate realistic magnitudes of the spatial distribution of the annual mean surface stress field and are seen to reproduce realistically its observed spatial pattern. Similar features are observed in the simulations of the annual variance field. The models perform well over almost all the tropical regions apart from a few. Of these, the simulations over Somali are interesting. Over this region, the models are seen to underestimate the annual mean zonal and meridional stresses. There is also wide variance between the different models in simulating these quantities. 44 refs.

  15. Large scale structure and baryogenesis

    International Nuclear Information System (INIS)

    Kirilova, D.P.; Chizhov, M.V.

    2001-08-01

    We discuss a possible connection between the large scale structure formation and the baryogenesis in the universe. An update review of the observational indications for the presence of a very large scale 120h -1 Mpc in the distribution of the visible matter of the universe is provided. The possibility to generate a periodic distribution with the characteristic scale 120h -1 Mpc through a mechanism producing quasi-periodic baryon density perturbations during inflationary stage, is discussed. The evolution of the baryon charge density distribution is explored in the framework of a low temperature boson condensate baryogenesis scenario. Both the observed very large scale of a the visible matter distribution in the universe and the observed baryon asymmetry value could naturally appear as a result of the evolution of a complex scalar field condensate, formed at the inflationary stage. Moreover, for some model's parameters a natural separation of matter superclusters from antimatter ones can be achieved. (author)

  16. Demographic, socioeconomic and environmental changes affecting circulation of neglected tropical diseases in Egypt.

    Science.gov (United States)

    Abou-El-Naga, Iman F

    2015-11-01

    Egypt has been plagued by many neglected tropical diseases since Pharaonic time. These diseases are Schistosomiasis, soil-transmitted helminthiasis, lymphatic filariasis, leishmaniasis and fascioliasis beside the epidermal parasitic skin diseases. Indeed, theses diseases still persist as public health problem in the country by the influence of demographic, socioeconomic and environmental obstacles. This study seeks for understanding the contribution of each factor in each obstacle in neglected tropical diseases perpetuation which in turn could help the governorate in planning integrated control strategies. It was found that poverty, unregulated urbanization and inadequate sanitation are important socioeconomic factors that have great effect on the transmission dynamics of the diseases. The environmental factors which affect the epidemiology of these diseases in the country are scarcity of water, construction of dams, land reclamation for agriculture beside the climate factors. Unfortunately, the panic increase in the population growth rate minimizes the efforts done by the governorate to elevate the public health services. These conditions also affect the transmission of epidermal parasitic skin diseases including scabies, head lice and hookworm-related cutaneous larva migrans. The control programs and the recommendations to combat the diseases were discussed. The present study showed that the ecological factors affecting each neglected tropical disease in Egypt are somewhat similar which makes it worthy to develop an integrated control approaches aiming at improving the leading factors of neglected tropical diseases circulation in the country. Copyright © 2015 Hainan Medical College. Production and hosting by Elsevier B.V. All rights reserved.

  17. The ability of general circulation models to simulate tropical cyclones and their precursors over the North Atlantic main development region

    Energy Technology Data Exchange (ETDEWEB)

    Daloz, Anne Sophie; Chauvin, Fabrice [Groupe de Modelisation Grande Echelle et Climat, CNRM-GAME, Meteo-France, Toulouse Cedex 1 (France); Walsh, Kevin [University of Melbourne, School of Earth Sciences, Melbourne, VIC (Australia); Lavender, Sally; Abbs, Deborah [CSIRO Atmospheric and Marine Research, Aspendale, VIC (Australia); Roux, Frank [Universite de Toulouse and Centre National de la Recherche Scientifique, Laboratoire d' Aerologie, Toulouse (France)

    2012-10-15

    The ability of General Circulation Models (GCMs) to generate Tropical Cyclones (TCs) over the North Atlantic Main Development Region (MDR; 10-20 N, 20-80 W; Goldenberg and Shapiro in J Clim 9:1169-1187, 1996) is examined through a subset of ocean-atmosphere coupled simulations from the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel data set and a high-resolution (0.5 ) Sea Surface Temperature (SST)-forced simulation from the Australian Conformal-Cubic Atmospheric Model GCM. The results are compared with National Center for Environmental Prediction (NCEP-2) and European Center for Medium Range Weather Forecasts Re-Analysis (ERA-40) reanalyses over a common period from 1980 to 1998. Important biases in the representation of the TC activity are encountered over the MDR. This study emphasizes the strong link in the GCMs between African Easterly Waves (AEWs) and TC activity in this region. However, the generation of AEWs is not a sufficient condition alone for the models to produce TCs. Precipitation over the Sahel, especially rainfall over the Fouta Djallon highlands (cf. Fig. 1), is playing a role in the generation of TCs over the MDR. The influence of large-scale fields such as SST, vertical wind shear and tropospheric humidity on TC genesis is also examined. The ability of TC genesis indices, such as the Genesis Potential Index and the Convective Yearly Genesis Potential, to represent TC activity over the MDR in simulations at low to high spatial resolutions is analysed. These indices are found to be a reasonable method for comparing cyclogenesis in different models, even though other factors such as AEW activity should also be considered. (orig.)

  18. Large-scale solar heat

    Energy Technology Data Exchange (ETDEWEB)

    Tolonen, J.; Konttinen, P.; Lund, P. [Helsinki Univ. of Technology, Otaniemi (Finland). Dept. of Engineering Physics and Mathematics

    1998-12-31

    In this project a large domestic solar heating system was built and a solar district heating system was modelled and simulated. Objectives were to improve the performance and reduce costs of a large-scale solar heating system. As a result of the project the benefit/cost ratio can be increased by 40 % through dimensioning and optimising the system at the designing stage. (orig.)

  19. Wind-induced circulation in a large tropical lagoon: Chetumal Bay

    Science.gov (United States)

    Palacios, E.; Carrillo, L.

    2013-05-01

    Chetumal Bay is a large tropical lagoon located at the Mesoamerican Reef System. Windinduced circulation in this basin was investigated by using direct measurements of current, sea level, and 2d barotropic numerical model. Acoustic Doppler Profiler (ADP) transects covering the north of Chetumal Bay during two campaigns September 2006 and March 2007 were used. The 2d barotropic numerical model was ROMs based and wind forced. Wind information was obtained from a meteorological station located at ECOSUR Chetumal. Sea level data was collected from a pressure sensor deployed in the lagoon. A seasonal pattern of circulation was observed. From observations, during September 2006, a northward flow was shown in most part of the bay and a southward flow in the eastern coast was observed with velocities ranged from 6 cm s-1 to 36 cm s-1. In March 2007, the current pattern was more complex; divergences and converges were identified. The dominant circulation was northward in eastern portion, and southward in the central and western zone. The average current speed was 6 cm s-1 with maximum values of 26 -34 cm s-1. During September 2006 predominant wind was easternsoutheastern and during March 2007, northerly wind events were recorded. Sea level amplitude responded quickly to changes in the magnitude and direction of the wind. Results of sea level and circulation from the 2d barotropic numerical model agreed with observations at first approximation.

  20. Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

    Science.gov (United States)

    Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

    2010-12-01

    Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how

  1. Influence of cloud radiative effects on tropical circulation and hydrological cycle in the Mid-Holocene

    Science.gov (United States)

    Izumi, Kenji; Kageyama, Masa; Bony, Sandrine; Braconnot, Pascale

    2016-04-01

    Paleoenvironmental data in particular, vegetation and lake-status at mid-Holocene (6,000 years ago) in Sahara shows that African monsoon extended much further north than today. Much of this change results from the changes in insolation driven by precession of the Earth's orbit, but in the state-of-the-art climate models, this factor alone is insufficient to explain the magnitude of the change. Previous studies showed that ocean and vegetation feedbacks affect the mid-Holocene monsoon and that the incorporation of these feedbacks in models improves the simulation of the hydrological cycle. However, it is not sufficient to reduce the discrepancies between simulated and reconstructed surface climates. In this study, we investigate the extent to which the simulation of cloud-radiative effects matters for the simulation of paleo-climatic changes, and past changes in the position and strength of the tropical rain belts in particular. This is done by running a general circulation model with and without clouds-radiation interactions using the IPSL model. The impact of cloud -radiative effects, which prevents the precipitation band to move north, on the tropical circulation and precipitation changes in mid-Holocene experiments will be discussed. Additionally, we will show the simulated effects of land cover change over Sahara.

  2. Japanese large-scale interferometers

    CERN Document Server

    Kuroda, K; Miyoki, S; Ishizuka, H; Taylor, C T; Yamamoto, K; Miyakawa, O; Fujimoto, M K; Kawamura, S; Takahashi, R; Yamazaki, T; Arai, K; Tatsumi, D; Ueda, A; Fukushima, M; Sato, S; Shintomi, T; Yamamoto, A; Suzuki, T; Saitô, Y; Haruyama, T; Sato, N; Higashi, Y; Uchiyama, T; Tomaru, T; Tsubono, K; Ando, M; Takamori, A; Numata, K; Ueda, K I; Yoneda, H; Nakagawa, K; Musha, M; Mio, N; Moriwaki, S; Somiya, K; Araya, A; Kanda, N; Telada, S; Sasaki, M; Tagoshi, H; Nakamura, T; Tanaka, T; Ohara, K

    2002-01-01

    The objective of the TAMA 300 interferometer was to develop advanced technologies for kilometre scale interferometers and to observe gravitational wave events in nearby galaxies. It was designed as a power-recycled Fabry-Perot-Michelson interferometer and was intended as a step towards a final interferometer in Japan. The present successful status of TAMA is presented. TAMA forms a basis for LCGT (large-scale cryogenic gravitational wave telescope), a 3 km scale cryogenic interferometer to be built in the Kamioka mine in Japan, implementing cryogenic mirror techniques. The plan of LCGT is schematically described along with its associated R and D.

  3. Variability in warm-season atmospheric circulation and precipitation patterns over subtropical South America: relationships between the South Atlantic convergence zone and large-scale organized convection over the La Plata basin

    Science.gov (United States)

    Mattingly, Kyle S.; Mote, Thomas L.

    2017-01-01

    Warm-season precipitation variability over subtropical South America is characterized by an inverse relationship between the South Atlantic convergence zone (SACZ) and precipitation over the central and western La Plata basin of southeastern South America. This study extends the analysis of this "South American Seesaw" precipitation dipole to relationships between the SACZ and large, long-lived mesoscale convective systems (LLCSs) over the La Plata basin. By classifying SACZ events into distinct continental and oceanic categories and building a logistic regression model that relates LLCS activity across the region to continental and oceanic SACZ precipitation, a detailed account of spatial variability in the out-of-phase coupling between the SACZ and large-scale organized convection over the La Plata basin is provided. Enhanced precipitation in the continental SACZ is found to result in increased LLCS activity over northern, northeastern, and western sections of the La Plata basin, in association with poleward atmospheric moisture flux from the Amazon basin toward these regions, and a decrease in the probability of LLCS occurrence over the southeastern La Plata basin. Increased oceanic SACZ precipitation, however, was strongly related to reduced atmospheric moisture and decreased probability of LLCS occurrence over nearly the entire La Plata basin. These results suggest that continental SACZ activity and large-scale organized convection over the northern and eastern sections of the La Plata basin are closely tied to atmospheric moisture transport from the Amazon basin, while the warm coastal Brazil Current may also play an important role as an evaporative moisture source for LLCSs over the central and western La Plata basin.

  4. Large scale biomimetic membrane arrays

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Perry, Mark; Vogel, Jörg

    2009-01-01

    To establish planar biomimetic membranes across large scale partition aperture arrays, we created a disposable single-use horizontal chamber design that supports combined optical-electrical measurements. Functional lipid bilayers could easily and efficiently be established across CO2 laser micro......-structured 8 x 8 aperture partition arrays with average aperture diameters of 301 +/- 5 mu m. We addressed the electro-physical properties of the lipid bilayers established across the micro-structured scaffold arrays by controllable reconstitution of biotechnological and physiological relevant membrane...... peptides and proteins. Next, we tested the scalability of the biomimetic membrane design by establishing lipid bilayers in rectangular 24 x 24 and hexagonal 24 x 27 aperture arrays, respectively. The results presented show that the design is suitable for further developments of sensitive biosensor assays...

  5. Conference on Large Scale Optimization

    CERN Document Server

    Hearn, D; Pardalos, P

    1994-01-01

    On February 15-17, 1993, a conference on Large Scale Optimization, hosted by the Center for Applied Optimization, was held at the University of Florida. The con­ ference was supported by the National Science Foundation, the U. S. Army Research Office, and the University of Florida, with endorsements from SIAM, MPS, ORSA and IMACS. Forty one invited speakers presented papers on mathematical program­ ming and optimal control topics with an emphasis on algorithm development, real world applications and numerical results. Participants from Canada, Japan, Sweden, The Netherlands, Germany, Belgium, Greece, and Denmark gave the meeting an important international component. At­ tendees also included representatives from IBM, American Airlines, US Air, United Parcel Serice, AT & T Bell Labs, Thinking Machines, Army High Performance Com­ puting Research Center, and Argonne National Laboratory. In addition, the NSF sponsored attendance of thirteen graduate students from universities in the United States and abro...

  6. Large scale nuclear structure studies

    International Nuclear Information System (INIS)

    Faessler, A.

    1985-01-01

    Results of large scale nuclear structure studies are reported. The starting point is the Hartree-Fock-Bogoliubov solution with angular momentum and proton and neutron number projection after variation. This model for number and spin projected two-quasiparticle excitations with realistic forces yields in sd-shell nuclei similar good results as the 'exact' shell-model calculations. Here the authors present results for a pf-shell nucleus 46 Ti and results for the A=130 mass region where they studied 58 different nuclei with the same single-particle energies and the same effective force derived from a meson exchange potential. They carried out a Hartree-Fock-Bogoliubov variation after mean field projection in realistic model spaces. In this way, they determine for each yrast state the optimal mean Hartree-Fock-Bogoliubov field. They apply this method to 130 Ce and 128 Ba using the same effective nucleon-nucleon interaction. (Auth.)

  7. Reviving large-scale projects

    International Nuclear Information System (INIS)

    Desiront, A.

    2003-01-01

    For the past decade, most large-scale hydro development projects in northern Quebec have been put on hold due to land disputes with First Nations. Hydroelectric projects have recently been revived following an agreement signed with Aboriginal communities in the province who recognized the need to find new sources of revenue for future generations. Many Cree are working on the project to harness the waters of the Eastmain River located in the middle of their territory. The work involves building an 890 foot long dam, 30 dikes enclosing a 603 square-km reservoir, a spillway, and a power house with 3 generating units with a total capacity of 480 MW of power for start-up in 2007. The project will require the use of 2,400 workers in total. The Cree Construction and Development Company is working on relations between Quebec's 14,000 Crees and the James Bay Energy Corporation, the subsidiary of Hydro-Quebec which is developing the project. Approximately 10 per cent of the $735-million project has been designated for the environmental component. Inspectors ensure that the project complies fully with environmental protection guidelines. Total development costs for Eastmain-1 are in the order of $2 billion of which $735 million will cover work on site and the remainder will cover generating units, transportation and financial charges. Under the treaty known as the Peace of the Braves, signed in February 2002, the Quebec government and Hydro-Quebec will pay the Cree $70 million annually for 50 years for the right to exploit hydro, mining and forest resources within their territory. The project comes at a time when electricity export volumes to the New England states are down due to growth in Quebec's domestic demand. Hydropower is a renewable and non-polluting source of energy that is one of the most acceptable forms of energy where the Kyoto Protocol is concerned. It was emphasized that large-scale hydro-electric projects are needed to provide sufficient energy to meet both

  8. Circulation and suspended sediment dynamics in a tropical estuary under different morphological setting

    Directory of Open Access Journals (Sweden)

    BÁRBARA P. PAIVA

    2016-01-01

    Full Text Available ABSTRACT Estuarine processes are directly related to the interaction of its forcing conditions with the local morphology. In this study we assess the implications of the opening of a new inlet on the hydrodynamics and suspended sediment concentration (SSC. A set of physical parameters have been measured in the Itanhém river estuary, a small, shallow and mangrove fringed tropical estuary in Northeastern Brazil. Field surveys have been conducted in August 2007 and January 2008, separated by an important morphological change. Our observations show that even shortening the lower estuary channel in 2 km, the inlet opening did not imply in changes in the estuarine circulation. However, SSC increased after the inlet opening. General estuarine circulation showed synodical modulation of tidal asymmetry and residual suspended sediment transport. The estuary showed flood dominance at spring tide and ebb dominance at neap tide. Although not directly changing the estuarine hydrodynamics, the morphological change resulted in an important increase in SSC. This increase might be related to a facilitated import of inner shelf sediment through a shorter channel, having important implications for the estuarine sedimentation processes.

  9. Large Scale Glazed Concrete Panels

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Today, there is a lot of focus on concrete surface’s aesthitic potential, both globally and locally. World famous architects such as Herzog De Meuron, Zaha Hadid, Richard Meyer and David Chippenfield challenge the exposure of concrete in their architecture. At home, this trend can be seen...... in the crinkly façade of DR-Byen (the domicile of the Danish Broadcasting Company) by architect Jean Nouvel and Zaha Hadid’s Ordrupgård’s black curved smooth concrete surfaces. Furthermore, one can point to initiatives such as “Synlig beton” (visible concrete) that can be seen on the website www.......synligbeton.dk and spæncom’s aesthetic relief effects by the designer Line Kramhøft (www.spaencom.com). It is my hope that the research-development project “Lasting large scale glazed concrete formwork,” I am working on at DTU, department of Architectural Engineering will be able to complement these. It is a project where I...

  10. Large scale cluster computing workshop

    International Nuclear Information System (INIS)

    Dane Skow; Alan Silverman

    2002-01-01

    Recent revolutions in computer hardware and software technologies have paved the way for the large-scale deployment of clusters of commodity computers to address problems heretofore the domain of tightly coupled SMP processors. Near term projects within High Energy Physics and other computing communities will deploy clusters of scale 1000s of processors and be used by 100s to 1000s of independent users. This will expand the reach in both dimensions by an order of magnitude from the current successful production facilities. The goals of this workshop were: (1) to determine what tools exist which can scale up to the cluster sizes foreseen for the next generation of HENP experiments (several thousand nodes) and by implication to identify areas where some investment of money or effort is likely to be needed. (2) To compare and record experimences gained with such tools. (3) To produce a practical guide to all stages of planning, installing, building and operating a large computing cluster in HENP. (4) To identify and connect groups with similar interest within HENP and the larger clustering community

  11. Large scale cross hole testing

    International Nuclear Information System (INIS)

    Ball, J.K.; Black, J.H.; Doe, T.

    1991-05-01

    As part of the Site Characterisation and Validation programme the results of the large scale cross hole testing have been used to document hydraulic connections across the SCV block, to test conceptual models of fracture zones and obtain hydrogeological properties of the major hydrogeological features. The SCV block is highly heterogeneous. This heterogeneity is not smoothed out even over scales of hundreds of meters. Results of the interpretation validate the hypothesis of the major fracture zones, A, B and H; not much evidence of minor fracture zones is found. The uncertainty in the flow path, through the fractured rock, causes sever problems in interpretation. Derived values of hydraulic conductivity were found to be in a narrow range of two to three orders of magnitude. Test design did not allow fracture zones to be tested individually. This could be improved by testing the high hydraulic conductivity regions specifically. The Piezomac and single hole equipment worked well. Few, if any, of the tests ran long enough to approach equilibrium. Many observation boreholes showed no response. This could either be because there is no hydraulic connection, or there is a connection but a response is not seen within the time scale of the pumping test. The fractional dimension analysis yielded credible results, and the sinusoidal testing procedure provided an effective means of identifying the dominant hydraulic connections. (10 refs.) (au)

  12. Large-scale pool fires

    Directory of Open Access Journals (Sweden)

    Steinhaus Thomas

    2007-01-01

    Full Text Available A review of research into the burning behavior of large pool fires and fuel spill fires is presented. The features which distinguish such fires from smaller pool fires are mainly associated with the fire dynamics at low source Froude numbers and the radiative interaction with the fire source. In hydrocarbon fires, higher soot levels at increased diameters result in radiation blockage effects around the perimeter of large fire plumes; this yields lower emissive powers and a drastic reduction in the radiative loss fraction; whilst there are simplifying factors with these phenomena, arising from the fact that soot yield can saturate, there are other complications deriving from the intermittency of the behavior, with luminous regions of efficient combustion appearing randomly in the outer surface of the fire according the turbulent fluctuations in the fire plume. Knowledge of the fluid flow instabilities, which lead to the formation of large eddies, is also key to understanding the behavior of large-scale fires. Here modeling tools can be effectively exploited in order to investigate the fluid flow phenomena, including RANS- and LES-based computational fluid dynamics codes. The latter are well-suited to representation of the turbulent motions, but a number of challenges remain with their practical application. Massively-parallel computational resources are likely to be necessary in order to be able to adequately address the complex coupled phenomena to the level of detail that is necessary.

  13. Large-scale galaxy bias

    Science.gov (United States)

    Desjacques, Vincent; Jeong, Donghui; Schmidt, Fabian

    2018-02-01

    This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy statistics. We then review the excursion-set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

  14. Large-scale galaxy bias

    Science.gov (United States)

    Jeong, Donghui; Desjacques, Vincent; Schmidt, Fabian

    2018-01-01

    Here, we briefly introduce the key results of the recent review (arXiv:1611.09787), whose abstract is as following. This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy (or halo) statistics. We then review the excursion set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

  15. Timeslice experiments for understanding regional climate projections: applications to the tropical hydrological cycle and European winter circulation

    Science.gov (United States)

    Chadwick, Robin; Douville, Hervé; Skinner, Christopher B.

    2017-11-01

    A set of atmosphere-only timeslice experiments are described, designed to examine the processes that cause regional climate change and inter-model uncertainty in coupled climate model responses to CO_2 forcing. The timeslice experiments are able to reproduce the pattern of regional climate change in the coupled models, and are applied here to two cases where inter-model uncertainty in future projections is large: the tropical hydrological cycle, and European winter circulation. In tropical forest regions, the plant physiological effect is the largest cause of hydrological cycle change in the two models that represent this process. This suggests that the CMIP5 ensemble mean may be underestimating the magnitude of water cycle change in these regions, due to the inclusion of models without the plant effect. SST pattern change is the dominant cause of precipitation and circulation change over the tropical oceans, and also appears to contribute to inter-model uncertainty in precipitation change over tropical land regions. Over Europe and the North Atlantic, uniform SST increases drive a poleward shift of the storm-track. However this does not consistently translate into an overall polewards storm-track shift, due to large circulation responses to SST pattern change, which varies across the models. Coupled model SST biases influence regional rainfall projections in regions such as the Maritime Continent, and so projections in these regions should be treated with caution.

  16. Groundwater circulations within a tropical humid andesitic volcanic watershed using the temperature as a tracer

    Science.gov (United States)

    Selles, Adrien; Violette, Sophie; Hendrayana, Heru

    2014-05-01

    Groundwater flow within volcano-detritic environment, is of prime importance to many human needs and activities, from the supply of clean drinking water to the extraction of hydrocarbons or geothermal energy. However, the heterogeneity of the geological formations makes difficult to quantify the groundwater spatial distribution. Moreover, its temporal variation in tropical humid regions is sometimes poorly known. For instance, the surronding of the Merapi volcano, in Central Java, Indonesia, is an area of high but seasonal rainfall, and extensive crop irrigation. It has a large population and a need to increase food and potable water supplies depending upon exploiting groundwater ressources. The stress on these resources increases with the intensification of the demography, the agricultural practices and the industrial exploitations. In order to implement a sustainable management of the water resources, the description of the groundwater circulations and the quantification of the resources is needed. A mutidisciplinary approach has been performed at the watershed scale, including geology, hydrogeochemistry and long term hydrogeological monitoring. The data synthesis and constisency have been confirm with a numerical model of physical processes. Based on a geological and geomorphological study, the hydrogeological watershed on the Eastern flank of the Merapi volcano is composed by an alternation of aquitards (mainly ashes, tuffs and clay) and aquifers (sand, gravel and boulders). The deep aquifers are agenced in conduit following the burried channel of the paleo-rivers. The eastern flank of Merapi provides excellent example of a volcanic-sedimentary environment. From 20 cold springs of 3 spring zones, sampled on 2 hydrological years (2011 to 2013), the study of the transfer into the saturated zone from upstream to downstream, given the geological context and topography, allows to estimate the role of supply from high and low altitudes to the recharge processes. The

  17. Sensitivity of tree ring growth to local and large-scale climate variability in a region of Southeastern Brazil

    Science.gov (United States)

    Venegas-González, Alejandro; Chagas, Matheus Peres; Anholetto Júnior, Claudio Roberto; Alvares, Clayton Alcarde; Roig, Fidel Alejandro; Tomazello Filho, Mario

    2016-01-01

    We explored the relationship between tree growth in two tropical species and local and large-scale climate variability in Southeastern Brazil. Tree ring width chronologies of Tectona grandis (teak) and Pinus caribaea (Caribbean pine) trees were compared with local (Water Requirement Satisfaction Index—WRSI, Standardized Precipitation Index—SPI, and Palmer Drought Severity Index—PDSI) and large-scale climate indices that analyze the equatorial pacific sea surface temperature (Trans-Niño Index-TNI and Niño-3.4-N3.4) and atmospheric circulation variations in the Southern Hemisphere (Antarctic Oscillation-AAO). Teak trees showed positive correlation with three indices in the current summer and fall. A significant correlation between WRSI index and Caribbean pine was observed in the dry season preceding tree ring formation. The influence of large-scale climate patterns was observed only for TNI and AAO, where there was a radial growth reduction in months preceding the growing season with positive values of the TNI in teak trees and radial growth increase (decrease) during December (March) to February (May) of the previous (current) growing season with positive phase of the AAO in teak (Caribbean pine) trees. The development of a new dendroclimatological study in Southeastern Brazil sheds light to local and large-scale climate influence on tree growth in recent decades, contributing in future climate change studies.

  18. Large Scale Processes and Extreme Floods in Brazil

    Science.gov (United States)

    Ribeiro Lima, C. H.; AghaKouchak, A.; Lall, U.

    2016-12-01

    Persistent large scale anomalies in the atmospheric circulation and ocean state have been associated with heavy rainfall and extreme floods in water basins of different sizes across the world. Such studies have emerged in the last years as a new tool to improve the traditional, stationary based approach in flood frequency analysis and flood prediction. Here we seek to advance previous studies by evaluating the dominance of large scale processes (e.g. atmospheric rivers/moisture transport) over local processes (e.g. local convection) in producing floods. We consider flood-prone regions in Brazil as case studies and the role of large scale climate processes in generating extreme floods in such regions is explored by means of observed streamflow, reanalysis data and machine learning methods. The dynamics of the large scale atmospheric circulation in the days prior to the flood events are evaluated based on the vertically integrated moisture flux and its divergence field, which are interpreted in a low-dimensional space as obtained by machine learning techniques, particularly supervised kernel principal component analysis. In such reduced dimensional space, clusters are obtained in order to better understand the role of regional moisture recycling or teleconnected moisture in producing floods of a given magnitude. The convective available potential energy (CAPE) is also used as a measure of local convection activities. We investigate for individual sites the exceedance probability in which large scale atmospheric fluxes dominate the flood process. Finally, we analyze regional patterns of floods and how the scaling law of floods with drainage area responds to changes in the climate forcing mechanisms (e.g. local vs large scale).

  19. Large-Scale Analysis of Relationships between Mineral Dust, Ice Cloud Properties, and Precipitation from Satellite Observations Using a Bayesian Approach: Theoretical Basis and First Results for the Tropical Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Lars Klüser

    2017-01-01

    Full Text Available Mineral dust and ice cloud observations from the Infrared Atmospheric Sounding Interferometer (IASI are used to assess the relationships between desert dust aerosols and ice clouds over the tropical Atlantic Ocean during the hurricane season 2008. Cloud property histograms are first adjusted for varying cloud top temperature or ice water path distributions with a Bayesian approach to account for meteorological constraints on the cloud variables. Then, histogram differences between dust load classes are used to describe the impact of dust load on cloud property statistics. The analysis of the histogram differences shows that ice crystal sizes are reduced with increasing aerosol load and ice cloud optical depth and ice water path are increased. The distributions of all three variables broaden and get less skewed in dusty environments. For ice crystal size the significant bimodality is reduced and the order of peaks is reversed. Moreover, it is shown that not only are distributions of ice cloud variables simply shifted linearly but also variance, skewness, and complexity of the cloud variable distributions are significantly affected. This implies that the whole cloud variable distributions have to be considered for indirect aerosol effects in any application for climate modelling.

  20. Ethics of large-scale change

    OpenAIRE

    Arler, Finn

    2006-01-01

      The subject of this paper is long-term large-scale changes in human society. Some very significant examples of large-scale change are presented: human population growth, human appropriation of land and primary production, the human use of fossil fuels, and climate change. The question is posed, which kind of attitude is appropriate when dealing with large-scale changes like these from an ethical point of view. Three kinds of approaches are discussed: Aldo Leopold's mountain thinking, th...

  1. The medium precipitation in Colombia by the light of the observations, the climatic simulation and the tropical medium circulation

    International Nuclear Information System (INIS)

    Montoya Gaviria, Gerardo de Jesus; Eslava R, Jesus Antonio; Pabon Caicedo, Jose Daniel

    2001-01-01

    An analysis of the physical mechanisms governing the annual precipitation cycle formation over the Colombian territory is made. This analysis is carried out using climate simulations, means Reanalysis values and is supported by the existing theory about the mean tropical circulation. Some results are: Judging by the wind discontinuity; the Inter tropical Convergence Zone (ITCZ) is fractionated over the South American Continent and remains all the year in the northern hemisphere in both oceans: Pacific and Atlantic. The low pressure system which forms in middle latitudes over the South American Continent during the Austral summer, deep penetrates onto tropical latitudes where, probably merges with the equatorial low of this season. There is a strong influence of the north eastern trades over the north eastern region of South America specially from December to February. As these winds enter onto the South American Continent, they associate with a current, does not yet mentioned in the existing literature, witch bounds the eastern side of the Andes and deep penetrates until middle latitudes in South America during this season. It is confirmed by the Reanalysis that seasonal migration of the ITCZ over Colombia may be used to explain the annual cycle precipitation formation over the most Colombia Territory. The results of this study are useful to have a more precise understanding of the tropical circulation over the Colombia Territory and can also be used in meteorological a hydrological modelling validation studies

  2. Large Scale Computations in Air Pollution Modelling

    DEFF Research Database (Denmark)

    Zlatev, Z.; Brandt, J.; Builtjes, P. J. H.

    Proceedings of the NATO Advanced Research Workshop on Large Scale Computations in Air Pollution Modelling, Sofia, Bulgaria, 6-10 July 1998......Proceedings of the NATO Advanced Research Workshop on Large Scale Computations in Air Pollution Modelling, Sofia, Bulgaria, 6-10 July 1998...

  3. Automating large-scale reactor systems

    International Nuclear Information System (INIS)

    Kisner, R.A.

    1985-01-01

    This paper conveys a philosophy for developing automated large-scale control systems that behave in an integrated, intelligent, flexible manner. Methods for operating large-scale systems under varying degrees of equipment degradation are discussed, and a design approach that separates the effort into phases is suggested. 5 refs., 1 fig

  4. Decentralized Large-Scale Power Balancing

    DEFF Research Database (Denmark)

    Halvgaard, Rasmus; Jørgensen, John Bagterp; Poulsen, Niels Kjølstad

    2013-01-01

    problem is formulated as a centralized large-scale optimization problem but is then decomposed into smaller subproblems that are solved locally by each unit connected to an aggregator. For large-scale systems the method is faster than solving the full problem and can be distributed to include an arbitrary...

  5. Large scale network-centric distributed systems

    CERN Document Server

    Sarbazi-Azad, Hamid

    2014-01-01

    A highly accessible reference offering a broad range of topics and insights on large scale network-centric distributed systems Evolving from the fields of high-performance computing and networking, large scale network-centric distributed systems continues to grow as one of the most important topics in computing and communication and many interdisciplinary areas. Dealing with both wired and wireless networks, this book focuses on the design and performance issues of such systems. Large Scale Network-Centric Distributed Systems provides in-depth coverage ranging from ground-level hardware issu

  6. Large-scale numerical simulations of plasmas

    International Nuclear Information System (INIS)

    Hamaguchi, Satoshi

    2004-01-01

    The recent trend of large scales simulations of fusion plasma and processing plasmas is briefly summarized. Many advanced simulation techniques have been developed for fusion plasmas and some of these techniques are now applied to analyses of processing plasmas. (author)

  7. Superconducting materials for large scale applications

    International Nuclear Information System (INIS)

    Dew-Hughes, D.

    1975-01-01

    Applications of superconductors capable of carrying large current densities in large-scale electrical devices are examined. Discussions are included on critical current density, superconducting materials available, and future prospects for improved superconducting materials. (JRD)

  8. Large-scale computing with Quantum Espresso

    International Nuclear Information System (INIS)

    Giannozzi, P.; Cavazzoni, C.

    2009-01-01

    This paper gives a short introduction to Quantum Espresso: a distribution of software for atomistic simulations in condensed-matter physics, chemical physics, materials science, and to its usage in large-scale parallel computing.

  9. Large-scale regions of antimatter

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  10. Large-scale regions of antimatter

    Energy Technology Data Exchange (ETDEWEB)

    Grobov, A. V., E-mail: alexey.grobov@gmail.com; Rubin, S. G., E-mail: sgrubin@mephi.ru [National Research Nuclear University MEPhI (Russian Federation)

    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.

  11. Large-scale grid management; Storskala Nettforvaltning

    Energy Technology Data Exchange (ETDEWEB)

    Langdal, Bjoern Inge; Eggen, Arnt Ove

    2003-07-01

    The network companies in the Norwegian electricity industry now have to establish a large-scale network management, a concept essentially characterized by (1) broader focus (Broad Band, Multi Utility,...) and (2) bigger units with large networks and more customers. Research done by SINTEF Energy Research shows so far that the approaches within large-scale network management may be structured according to three main challenges: centralization, decentralization and out sourcing. The article is part of a planned series.

  12. Political consultation and large-scale research

    International Nuclear Information System (INIS)

    Bechmann, G.; Folkers, H.

    1977-01-01

    Large-scale research and policy consulting have an intermediary position between sociological sub-systems. While large-scale research coordinates science, policy, and production, policy consulting coordinates science, policy and political spheres. In this very position, large-scale research and policy consulting lack of institutional guarantees and rational back-ground guarantee which are characteristic for their sociological environment. This large-scale research can neither deal with the production of innovative goods under consideration of rentability, nor can it hope for full recognition by the basis-oriented scientific community. Policy consulting knows neither the competence assignment of the political system to make decisions nor can it judge succesfully by the critical standards of the established social science, at least as far as the present situation is concerned. This intermediary position of large-scale research and policy consulting has, in three points, a consequence supporting the thesis which states that this is a new form of institutionalization of science: These are: 1) external control, 2) the organization form, 3) the theoretical conception of large-scale research and policy consulting. (orig.) [de

  13. Large-Scale Processes Associated with Inter-Decadal and Inter-Annual Early Spring Rainfall Variability in Taiwan

    Directory of Open Access Journals (Sweden)

    Jau-Ming Chen

    2016-02-01

    Full Text Available Early spring (March - April rainfall in Taiwan exhibits evident and distinct inter-annual and inter-decadal variability. The inter-annual varibility has a positive correlation with the El Niño/Southern Oscillation while the inter-decadal variability features a phase change beginning in the late 1970s, coherent with the major phase change in the Pacific decadal oscillation. Rainfall variability in both timescales is regulated by large-scale processes showing consistent dynamic features. Rainfall increases are associated with positive sea surface temperature (SST anomalies in the tropical eastern Pacific and negative SST anomalies in the tropical central Pacific. An anomalous lower-level divergent center appears in the tropical central Pacific. Via a Rossby-wave-like response, an anomalous lower-level anticyclone appears to the southeast of Taiwan over the Philippine Sea-tropical western Pacific region, which is accompanied by an anomalous cyclone to the north-northeast of Taiwan. Both circulation anomalies induce anomalous southwesterly flows to enhance moisture flux from the South China Sea onto Taiwan, resulting in significant moisture convergence nearby Taiwan. With enhanced moisture supplied by anomalous southwesterly flows, significant rainfall increases occur in both inter-annual and inter-decadal timescales in early spring rainfall on Taiwan.

  14. Dissecting the large-scale galactic conformity

    Science.gov (United States)

    Seo, Seongu

    2018-01-01

    Galactic conformity is an observed phenomenon that galaxies located in the same region have similar properties such as star formation rate, color, gas fraction, and so on. The conformity was first observed among galaxies within in the same halos (“one-halo conformity”). The one-halo conformity can be readily explained by mutual interactions among galaxies within a halo. Recent observations however further witnessed a puzzling connection among galaxies with no direct interaction. In particular, galaxies located within a sphere of ~5 Mpc radius tend to show similarities, even though the galaxies do not share common halos with each other ("two-halo conformity" or “large-scale conformity”). Using a cosmological hydrodynamic simulation, Illustris, we investigate the physical origin of the two-halo conformity and put forward two scenarios. First, back-splash galaxies are likely responsible for the large-scale conformity. They have evolved into red galaxies due to ram-pressure stripping in a given galaxy cluster and happen to reside now within a ~5 Mpc sphere. Second, galaxies in strong tidal field induced by large-scale structure also seem to give rise to the large-scale conformity. The strong tides suppress star formation in the galaxies. We discuss the importance of the large-scale conformity in the context of galaxy evolution.

  15. Maintenance of Austral Summertime Upper-Tropospheric Circulation over Tropical South America: The Bolivian High-Nordeste Low System.

    Science.gov (United States)

    Chen, Tsing-Chang; Weng, Shu-Ping; Schubert, Siegfried

    1999-07-01

    Using the NASA/GEOS reanalysis data for 1980-95, the austral-summer stationary eddies in the tropical-subtropical Southern Hemisphere are examined in two wave regimes: long and short wave (wave 1 and waves 2-6, respectively). The basic structure of the Bolivian high-Nordeste low (BH-NL) system is formed by a short-wave train across South America but modulated by the long-wave regime. The short-wave train exhibits a monsoonlike vertical phase reversal in the midtroposphere and a quarter-wave phase shift relative to the divergent circulation. As inferred from (a) the spatial relationship between the streamfunction and velocity potential and (b) the structure of the divergent circulation, the short-wave train forming the BH-NL system is maintained by South American local heating and remote African heating, while the long-wave regime is maintained by western tropical Pacific heating.The maintenance of the stationary waves in the two wave regimes is further illustrated by a simple diagnostic scheme that includes the velocity-potential maintenance equation (which links velocity potential and diabatic heating) and the streamfunction budget (which is the inverse Laplacian transform of the vorticity equation). Some simple relationships between streamfunction and velocity potential for both wave regimes are established to substantiate the links between diabatic heating and streamfunction; of particular interest is a Sverdrup balance in the short-wave regime. This simplified vorticity equation explains the vertical structure of the short-wave train associated with the BH-NL system and its spatial relationship with the divergent circulation.Based upon the diagnostic analysis of its maintenance a simple forced barotropic model is adopted to simulate the BH-NL system with idealized forcings, which imitates the real 200-mb divergence centers over South America, Africa, and the tropical Pacific. Numerical simulations demonstrate that the formation of the BH-NL system is affected

  16. Influence of solar radiation absorbed by phytoplankton on the thermal structure and circulation of the tropical Atlantic Ocean

    Science.gov (United States)

    Frouin, Robert; Ueyoshi, Kyozo; Kampel, Milton

    2007-09-01

    Numerical experiments conducted with an ocean general ocean circulation model reveal the potential influence of solar radiation absorbed by phytoplankton on the thermal structure and currents of the Tropical Atlantic Ocean. In the model, solar radiation penetration is parameterized explicitly as a function of chlorophyll-a concentration, the major variable affecting water turbidity in the open ocean. Two types of runs are performed, a clear water (control) run with a constant minimum chlorophyll-a concentration of 0.02 mgm -3, and a turbid water (chlorophyll) run with space- and time-varying chlorophyll-a concentration from satellite data. The difference between results from the two runs yields the biological effects. In the chlorophyll run, nutrients and biology production are implicitly taken into account, even though biogeochemical processes are not explicitly included, since phytoplankton distribution, prescribed from observations, is the result of those processes. Due to phytoplankton-radiation forcing, the surface temperature is higher by 1-2 K on average annually in the region of the North Equatorial current, the Northern part of the South Equatorial current, and the Caribbean system, and by 3-4 K in the region of the Guinea current. In this region, upwelling is reduced, and heat trapped in the surface layers by phytoplankton is not easily removed. The surface temperature is lower by 1 K in the Northern region of the Benguela current, due to increased upwelling. At depth, the equatorial Atlantic is generally cooler, as well as the eastern part of the tropical basin (excluding the region of the sub-tropical gyres). The North and South equatorial currents, as well as the Equatorial undercurrent, are enhanced by as much as 3-4 cms -1, and the circulation of the subtropical gyres is increased. Pole-ward heat transport is slightly reduced North of 35°N, suggesting that phytoplankton, by increasing the horizontal return flow in the subtropical region, may exert a

  17. Growth Limits in Large Scale Networks

    DEFF Research Database (Denmark)

    Knudsen, Thomas Phillip

    limitations. The rising complexity of network management with the convergence of communications platforms is shown as problematic for both automatic management feasibility and for manpower resource management. In the fourth step the scope is extended to include the present society with the DDN project as its......The Subject of large scale networks is approached from the perspective of the network planner. An analysis of the long term planning problems is presented with the main focus on the changing requirements for large scale networks and the potential problems in meeting these requirements. The problems...... the fundamental technological resources in network technologies are analysed for scalability. Here several technological limits to continued growth are presented. The third step involves a survey of major problems in managing large scale networks given the growth of user requirements and the technological...

  18. Managing large-scale models: DBS

    International Nuclear Information System (INIS)

    1981-05-01

    A set of fundamental management tools for developing and operating a large scale model and data base system is presented. Based on experience in operating and developing a large scale computerized system, the only reasonable way to gain strong management control of such a system is to implement appropriate controls and procedures. Chapter I discusses the purpose of the book. Chapter II classifies a broad range of generic management problems into three groups: documentation, operations, and maintenance. First, system problems are identified then solutions for gaining management control are disucssed. Chapters III, IV, and V present practical methods for dealing with these problems. These methods were developed for managing SEAS but have general application for large scale models and data bases

  19. Accelerating sustainability in large-scale facilities

    CERN Multimedia

    Marina Giampietro

    2011-01-01

    Scientific research centres and large-scale facilities are intrinsically energy intensive, but how can big science improve its energy management and eventually contribute to the environmental cause with new cleantech? CERN’s commitment to providing tangible answers to these questions was sealed in the first workshop on energy management for large scale scientific infrastructures held in Lund, Sweden, on the 13-14 October.   Participants at the energy management for large scale scientific infrastructures workshop. The workshop, co-organised with the European Spallation Source (ESS) and  the European Association of National Research Facilities (ERF), tackled a recognised need for addressing energy issues in relation with science and technology policies. It brought together more than 150 representatives of Research Infrastrutures (RIs) and energy experts from Europe and North America. “Without compromising our scientific projects, we can ...

  20. Connection of the stratospheric QBO with global atmospheric general circulation and tropical SST. Part II: interdecadal variations

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Zeng-Zhen [Climate Prediction Center (Room 605), NCEP/NWS/NOAA, Camp Springs, MD (United States); Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Huang, Bohua; Kinter, James L. [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); George Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Wu, Zhaohua [Florida State University, Department of Earth, Ocean, and Atmospheric Science, and Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL (United States); Kumar, Arun [Climate Prediction Center (Room 605), NCEP/NWS/NOAA, Camp Springs, MD (United States)

    2012-01-15

    The interdecadal variation of the association of the stratospheric quasi-biennial oscillation (QBO) with tropical sea surface temperature (SST) anomalies (SSTA) and with the general circulation in the troposphere and lower stratosphere is examined using the ERA40 and NCEP/NCAR reanalyses, as well as other observation-based analyses. It is found that the relationship between the QBO and tropical SSTA changed once around 1978-1980, and again in 1993-1995. During 1966-1974, negative correlation between the QBO and NINO3.4 indices reached its maximum when the NINO3.4 index lagged the QBO by less than 6 months. Correspondingly, the positive correlations were observed when the NINO3.4 index led the QBO by about 11-13 months or lagged by about 12-18 months. However, maximum negative correlations were shifted from the NINO3.4 index lagging the QBO by about 0-6 months during 1966-1974 to about 3-12 months during 1985-1992. During 1975-1979, both the negative and positive correlations were relatively small and the QBO and ENSO were practically unrelated to each other. The phase-based QBO life cycle composites also confirm that, on average, there are two phase (6-7 months) delay in the evolution of the QBO-associated anomalous Walker circulation, tropical SST, atmospheric stability, and troposphere and lower stratosphere temperature anomalies during 1980-1994 in comparison with those in 1957-1978. The interdecadal variation of the association between the QBO and the troposphere variability may be largely due to the characteristic change of El Nino-Southern Oscillation. The irregularity of the QBO may play a secondary role in the interdecadal variation of the association. (orig.)

  1. Large-Scale Analysis of Art Proportions

    DEFF Research Database (Denmark)

    Jensen, Karl Kristoffer

    2014-01-01

    While literature often tries to impute mathematical constants into art, this large-scale study (11 databases of paintings and photos, around 200.000 items) shows a different truth. The analysis, consisting of the width/height proportions, shows a value of rarely if ever one (square) and with majo......While literature often tries to impute mathematical constants into art, this large-scale study (11 databases of paintings and photos, around 200.000 items) shows a different truth. The analysis, consisting of the width/height proportions, shows a value of rarely if ever one (square...

  2. The Expanded Large Scale Gap Test

    Science.gov (United States)

    1987-03-01

    NSWC TR 86-32 DTIC THE EXPANDED LARGE SCALE GAP TEST BY T. P. LIDDIARD D. PRICE RESEARCH AND TECHNOLOGY DEPARTMENT ’ ~MARCH 1987 Ap~proved for public...arises, to reduce the spread in the LSGT 50% gap value.) The worst charges, such as those with the highest or lowest densities, the largest re-pressed...Arlington, VA 22217 PE 62314N INS3A 1 RJ14E31 7R4TBK 11 TITLE (Include Security CIlmsilficatiorn The Expanded Large Scale Gap Test . 12. PEIRSONAL AUTHOR() T

  3. Configuration management in large scale infrastructure development

    NARCIS (Netherlands)

    Rijn, T.P.J. van; Belt, H. van de; Los, R.H.

    2000-01-01

    Large Scale Infrastructure (LSI) development projects such as the construction of roads, rail-ways and other civil engineering (water)works is tendered differently today than a decade ago. Traditional workflow requested quotes from construction companies for construction works where the works to be

  4. Large-scale Motion of Solar Filaments

    Indian Academy of Sciences (India)

    tribpo

    Large-scale Motion of Solar Filaments. Pavel Ambrož, Astronomical Institute of the Acad. Sci. of the Czech Republic, CZ-25165. Ondrejov, The Czech Republic. e-mail: pambroz@asu.cas.cz. Alfred Schroll, Kanzelhöehe Solar Observatory of the University of Graz, A-9521 Treffen,. Austria. e-mail: schroll@solobskh.ac.at.

  5. Sensitivity analysis for large-scale problems

    Science.gov (United States)

    Noor, Ahmed K.; Whitworth, Sandra L.

    1987-01-01

    The development of efficient techniques for calculating sensitivity derivatives is studied. The objective is to present a computational procedure for calculating sensitivity derivatives as part of performing structural reanalysis for large-scale problems. The scope is limited to framed type structures. Both linear static analysis and free-vibration eigenvalue problems are considered.

  6. Ethics of large-scale change

    DEFF Research Database (Denmark)

    Arler, Finn

    2006-01-01

    , which kind of attitude is appropriate when dealing with large-scale changes like these from an ethical point of view. Three kinds of approaches are discussed: Aldo Leopold's mountain thinking, the neoclassical economists' approach, and finally the so-called Concentric Circle Theories approach...

  7. The origin of large scale cosmic structure

    International Nuclear Information System (INIS)

    Jones, B.J.T.; Palmer, P.L.

    1985-01-01

    The paper concerns the origin of large scale cosmic structure. The evolution of density perturbations, the nonlinear regime (Zel'dovich's solution and others), the Gott and Rees clustering hierarchy, the spectrum of condensations, and biassed galaxy formation, are all discussed. (UK)

  8. Large-scale multimedia modeling applications

    International Nuclear Information System (INIS)

    Droppo, J.G. Jr.; Buck, J.W.; Whelan, G.; Strenge, D.L.; Castleton, K.J.; Gelston, G.M.

    1995-08-01

    Over the past decade, the US Department of Energy (DOE) and other agencies have faced increasing scrutiny for a wide range of environmental issues related to past and current practices. A number of large-scale applications have been undertaken that required analysis of large numbers of potential environmental issues over a wide range of environmental conditions and contaminants. Several of these applications, referred to here as large-scale applications, have addressed long-term public health risks using a holistic approach for assessing impacts from potential waterborne and airborne transport pathways. Multimedia models such as the Multimedia Environmental Pollutant Assessment System (MEPAS) were designed for use in such applications. MEPAS integrates radioactive and hazardous contaminants impact computations for major exposure routes via air, surface water, ground water, and overland flow transport. A number of large-scale applications of MEPAS have been conducted to assess various endpoints for environmental and human health impacts. These applications are described in terms of lessons learned in the development of an effective approach for large-scale applications

  9. Large-scale perspective as a challenge

    NARCIS (Netherlands)

    Plomp, M.G.A.

    2012-01-01

    1. Scale forms a challenge for chain researchers: when exactly is something ‘large-scale’? What are the underlying factors (e.g. number of parties, data, objects in the chain, complexity) that determine this? It appears to be a continuum between small- and large-scale, where positioning on that

  10. Computing in Large-Scale Dynamic Systems

    NARCIS (Netherlands)

    Pruteanu, A.S.

    2013-01-01

    Software applications developed for large-scale systems have always been difficult to de- velop due to problems caused by the large number of computing devices involved. Above a certain network size (roughly one hundred), necessary services such as code updating, topol- ogy discovery and data

  11. Learning from large scale neural simulations

    DEFF Research Database (Denmark)

    Serban, Maria

    2017-01-01

    Large-scale neural simulations have the marks of a distinct methodology which can be fruitfully deployed to advance scientific understanding of the human brain. Computer simulation studies can be used to produce surrogate observational data for better conceptual models and new how...

  12. Large-Scale Outflows in Seyfert Galaxies

    Science.gov (United States)

    Colbert, E. J. M.; Baum, S. A.

    1995-12-01

    \\catcode`\\@=11 \\ialign{m @th#1hfil ##hfil \\crcr#2\\crcr\\sim\\crcr}}} \\catcode`\\@=12 Highly collimated outflows extend out to Mpc scales in many radio-loud active galaxies. In Seyfert galaxies, which are radio-quiet, the outflows extend out to kpc scales and do not appear to be as highly collimated. In order to study the nature of large-scale (>~1 kpc) outflows in Seyferts, we have conducted optical, radio and X-ray surveys of a distance-limited sample of 22 edge-on Seyfert galaxies. Results of the optical emission-line imaging and spectroscopic survey imply that large-scale outflows are present in >~{{1} /{4}} of all Seyferts. The radio (VLA) and X-ray (ROSAT) surveys show that large-scale radio and X-ray emission is present at about the same frequency. Kinetic luminosities of the outflows in Seyferts are comparable to those in starburst-driven superwinds. Large-scale radio sources in Seyferts appear diffuse, but do not resemble radio halos found in some edge-on starburst galaxies (e.g. M82). We discuss the feasibility of the outflows being powered by the active nucleus (e.g. a jet) or a circumnuclear starburst.

  13. Stability of large scale interconnected dynamical systems

    International Nuclear Information System (INIS)

    Akpan, E.P.

    1993-07-01

    Large scale systems modelled by a system of ordinary differential equations are considered and necessary and sufficient conditions are obtained for the uniform asymptotic connective stability of the systems using the method of cone-valued Lyapunov functions. It is shown that this model significantly improves the existing models. (author). 9 refs

  14. Large-scale structure of the Universe

    International Nuclear Information System (INIS)

    Doroshkevich, A.G.

    1978-01-01

    The problems, discussed at the ''Large-scale Structure of the Universe'' symposium are considered on a popular level. Described are the cell structure of galaxy distribution in the Universe, principles of mathematical galaxy distribution modelling. The images of cell structures, obtained after reprocessing with the computer are given. Discussed are three hypothesis - vortical, entropic, adiabatic, suggesting various processes of galaxy and galaxy clusters origin. A considerable advantage of the adiabatic hypothesis is recognized. The relict radiation, as a method of direct studying the processes taking place in the Universe is considered. The large-scale peculiarities and small-scale fluctuations of the relict radiation temperature enable one to estimate the turbance properties at the pre-galaxy stage. The discussion of problems, pertaining to studying the hot gas, contained in galaxy clusters, the interactions within galaxy clusters and with the inter-galaxy medium, is recognized to be a notable contribution into the development of theoretical and observational cosmology

  15. Emerging large-scale solar heating applications

    International Nuclear Information System (INIS)

    Wong, W.P.; McClung, J.L.

    2009-01-01

    Currently the market for solar heating applications in Canada is dominated by outdoor swimming pool heating, make-up air pre-heating and domestic water heating in homes, commercial and institutional buildings. All of these involve relatively small systems, except for a few air pre-heating systems on very large buildings. Together these applications make up well over 90% of the solar thermal collectors installed in Canada during 2007. These three applications, along with the recent re-emergence of large-scale concentrated solar thermal for generating electricity, also dominate the world markets. This paper examines some emerging markets for large scale solar heating applications, with a focus on the Canadian climate and market. (author)

  16. Emerging large-scale solar heating applications

    Energy Technology Data Exchange (ETDEWEB)

    Wong, W.P.; McClung, J.L. [Science Applications International Corporation (SAIC Canada), Ottawa, Ontario (Canada)

    2009-07-01

    Currently the market for solar heating applications in Canada is dominated by outdoor swimming pool heating, make-up air pre-heating and domestic water heating in homes, commercial and institutional buildings. All of these involve relatively small systems, except for a few air pre-heating systems on very large buildings. Together these applications make up well over 90% of the solar thermal collectors installed in Canada during 2007. These three applications, along with the recent re-emergence of large-scale concentrated solar thermal for generating electricity, also dominate the world markets. This paper examines some emerging markets for large scale solar heating applications, with a focus on the Canadian climate and market. (author)

  17. Challenges for Large Scale Structure Theory

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    I will describe some of the outstanding questions in Cosmology where answers could be provided by observations of the Large Scale Structure of the Universe at late times.I will discuss some of the theoretical challenges which will have to be overcome to extract this information from the observations. I will describe some of the theoretical tools that might be useful to achieve this goal. 

  18. Methods for Large-Scale Nonlinear Optimization.

    Science.gov (United States)

    1980-05-01

    STANFORD, CALIFORNIA 94305 METHODS FOR LARGE-SCALE NONLINEAR OPTIMIZATION by Philip E. Gill, Waiter Murray, I Michael A. Saunden, and Masgaret H. Wright...typical iteration can be partitioned so that where B is an m X m basise matrix. This partition effectively divides the vari- ables into three classes... attention is given to the standard of the coding or the documentation. A much better way of obtaining mathematical software is from a software library

  19. Large scale inhomogeneities and the cosmological principle

    International Nuclear Information System (INIS)

    Lukacs, B.; Meszaros, A.

    1984-12-01

    The compatibility of cosmologic principles and possible large scale inhomogeneities of the Universe is discussed. It seems that the strongest symmetry principle which is still compatible with reasonable inhomogeneities, is a full conformal symmetry in the 3-space defined by the cosmological velocity field, but even in such a case, the standard model is isolated from the inhomogeneous ones when the whole evolution is considered. (author)

  20. Fires in large scale ventilation systems

    International Nuclear Information System (INIS)

    Gregory, W.S.; Martin, R.A.; White, B.W.; Nichols, B.D.; Smith, P.R.; Leslie, I.H.; Fenton, D.L.; Gunaji, M.V.; Blythe, J.P.

    1991-01-01

    This paper summarizes the experience gained simulating fires in large scale ventilation systems patterned after ventilation systems found in nuclear fuel cycle facilities. The series of experiments discussed included: (1) combustion aerosol loading of 0.61x0.61 m HEPA filters with the combustion products of two organic fuels, polystyrene and polymethylemethacrylate; (2) gas dynamic and heat transport through a large scale ventilation system consisting of a 0.61x0.61 m duct 90 m in length, with dampers, HEPA filters, blowers, etc.; (3) gas dynamic and simultaneous transport of heat and solid particulate (consisting of glass beads with a mean aerodynamic diameter of 10μ) through the large scale ventilation system; and (4) the transport of heat and soot, generated by kerosene pool fires, through the large scale ventilation system. The FIRAC computer code, designed to predict fire-induced transients in nuclear fuel cycle facility ventilation systems, was used to predict the results of experiments (2) through (4). In general, the results of the predictions were satisfactory. The code predictions for the gas dynamics, heat transport, and particulate transport and deposition were within 10% of the experimentally measured values. However, the code was less successful in predicting the amount of soot generation from kerosene pool fires, probably due to the fire module of the code being a one-dimensional zone model. The experiments revealed a complicated three-dimensional combustion pattern within the fire room of the ventilation system. Further refinement of the fire module within FIRAC is needed. (orig.)

  1. Large-scale Complex IT Systems

    OpenAIRE

    Sommerville, Ian; Cliff, Dave; Calinescu, Radu; Keen, Justin; Kelly, Tim; Kwiatkowska, Marta; McDermid, John; Paige, Richard

    2011-01-01

    This paper explores the issues around the construction of large-scale complex systems which are built as 'systems of systems' and suggests that there are fundamental reasons, derived from the inherent complexity in these systems, why our current software engineering methods and techniques cannot be scaled up to cope with the engineering challenges of constructing such systems. It then goes on to propose a research and education agenda for software engineering that identifies the major challen...

  2. Large-scale complex IT systems

    OpenAIRE

    Sommerville, Ian; Cliff, Dave; Calinescu, Radu; Keen, Justin; Kelly, Tim; Kwiatkowska, Marta; McDermid, John; Paige, Richard

    2012-01-01

    12 pages, 2 figures This paper explores the issues around the construction of large-scale complex systems which are built as 'systems of systems' and suggests that there are fundamental reasons, derived from the inherent complexity in these systems, why our current software engineering methods and techniques cannot be scaled up to cope with the engineering challenges of constructing such systems. It then goes on to propose a research and education agenda for software engineering that ident...

  3. LAVA: Large scale Automated Vulnerability Addition

    Science.gov (United States)

    2016-05-23

    LAVA: Large-scale Automated Vulnerability Addition Brendan Dolan -Gavitt∗, Patrick Hulin†, Tim Leek†, Fredrich Ulrich†, Ryan Whelan† (Authors listed...released, and thus rapidly become stale. We can expect tools to have been trained to detect bugs that have been released. Given the commercial price tag...low TCN) and dead (low liveness) program data is a powerful one for vulnera- bility injection. The DUAs it identifies are internal program quantities

  4. Large-Scale Transit Signal Priority Implementation

    OpenAIRE

    Lee, Kevin S.; Lozner, Bailey

    2018-01-01

    In 2016, the District Department of Transportation (DDOT) deployed Transit Signal Priority (TSP) at 195 intersections in highly urbanized areas of Washington, DC. In collaboration with a broader regional implementation, and in partnership with the Washington Metropolitan Area Transit Authority (WMATA), DDOT set out to apply a systems engineering–driven process to identify, design, test, and accept a large-scale TSP system. This presentation will highlight project successes and lessons learned.

  5. Seasonal dependence of the predictable low-level circulation patterns over the tropical Indo-Pacific domain

    Science.gov (United States)

    Zhang, Tuantuan; Huang, Bohua; Yang, Song; Laohalertchai, Charoon

    2018-06-01

    The seasonal dependence of the prediction skill of 850-hPa monthly zonal wind over the tropical Indo-Pacific domain is examined using the ensemble reforecasts for 1983-2010 from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis and Reforecast (CFSRR) project. According to a maximum signal-to-noise empirical orthogonal function analysis, the most predictable patterns of atmospheric low-level circulation are associated with the developing and maturing phases of El Niño-Southern Oscillation (ENSO). The CFSv2 is capable of predicting these ENSO-related patterns up to 9-months in advance for all months, except for May-June when the effect of the spring barrier is strong. The other predictable climate processes associated with the low-level atmospheric circulation are more seasonally dependent. For winter and spring, the second most predictable patterns are associated with the ENSO decaying phase. Within these seasons, the monthly evolution of the predictable patterns is characterized by a southward shift of westerly wind anomalies, generated by the interaction between the annual cycle and the ENSO signals (i.e., the combination-mode). In general, the CFSv2 hindcast well predicts these patterns at least 5 months in advance for spring, while shows much lower skills for winter months. In summer, the second predictable patterns are associated with the western North Pacific (WNP) monsoon (i.e., the WNP anticyclone/cyclone) in short leads while associated with ENSO in longer leads (after 4-month lead). The second predictable patterns in fall are mainly associated with tropical Indian Ocean Dipole, which can be predicted 3 months in advance.

  6. Economically viable large-scale hydrogen liquefaction

    Science.gov (United States)

    Cardella, U.; Decker, L.; Klein, H.

    2017-02-01

    The liquid hydrogen demand, particularly driven by clean energy applications, will rise in the near future. As industrial large scale liquefiers will play a major role within the hydrogen supply chain, production capacity will have to increase by a multiple of today’s typical sizes. The main goal is to reduce the total cost of ownership for these plants by increasing energy efficiency with innovative and simple process designs, optimized in capital expenditure. New concepts must ensure a manageable plant complexity and flexible operability. In the phase of process development and selection, a dimensioning of key equipment for large scale liquefiers, such as turbines and compressors as well as heat exchangers, must be performed iteratively to ensure technological feasibility and maturity. Further critical aspects related to hydrogen liquefaction, e.g. fluid properties, ortho-para hydrogen conversion, and coldbox configuration, must be analysed in detail. This paper provides an overview on the approach, challenges and preliminary results in the development of efficient as well as economically viable concepts for large-scale hydrogen liquefaction.

  7. Connection of stratospheric QBO with global atmospheric general circulation and tropical SST. Part I: methodology and composite life cycle

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohua; Kinter, James L. [George Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Hu, Zeng-Zhen [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Climate Prediction Center (suite 605), NCEP/NWS/NOAA, Camp Springs, MD (United States); Wu, Zhaohua [Florida State University, Department of Earth, Ocean, and Atmospheric Science, and Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL (United States); Kumar, Arun [Climate Prediction Center (suite 605), NCEP/NWS/NOAA, Camp Springs, MD (United States)

    2012-01-15

    The stratospheric quasi-biennial oscillation (QBO) and its association with the interannual variability in the stratosphere and troposphere, as well as in tropical sea surface temperature anomalies (SSTA), are examined in the context of a QBO life cycle. The analysis is based on the ERA40 and NCEP/NCAR reanalyses, radiosonde observations at Singapore, and other observation-based datasets. Both reanalyses reproduce the QBO life cycle and its associated variability in the stratosphere reasonably well, except that some long-term changes are detected only in the NCEP/NCAR reanalysis. In order to separate QBO from variability on other time scales and to eliminate the long-term changes, a scale separation technique [Ensemble Empirical Mode Decomposition (EEMD)] is applied to the raw data. The QBO component of zonal wind anomalies at 30 hPa, extracted using the EEMD method, is defined as a QBO index. Using this index, the QBO life cycle composites of stratosphere and troposphere variables, as well as SSTA, are constructed and examined. The composite features in the stratosphere are generally consistent with previous investigations. The correlations between the QBO and tropical Pacific SSTA depend on the phase in a QBO life cycle. On average, cold (warm) SSTA peaks about half a year after the maximum westerlies (easterlies) at 30 hPa. The connection of the QBO with the troposphere seems to be associated with the differences of temperature anomalies between the stratosphere and troposphere. While the anomalies in the stratosphere propagate downward systematically, some anomalies in the troposphere develop and expand vertically. Therefore, it is possible that the temperature difference between the troposphere and stratosphere may alter the atmospheric stability and tropical deep convection, which modulates the Walker circulation and SSTA in the equatorial Pacific Ocean. (orig.)

  8. Connection of stratospheric QBO with global atmospheric general circulation and tropical SST. Part I: methodology and composite life cycle

    Science.gov (United States)

    Huang, Bohua; Hu, Zeng-Zhen; Kinter, James L.; Wu, Zhaohua; Kumar, Arun

    2012-01-01

    The stratospheric quasi-biennial oscillation (QBO) and its association with the interannual variability in the stratosphere and troposphere, as well as in tropical sea surface temperature anomalies (SSTA), are examined in the context of a QBO life cycle. The analysis is based on the ERA40 and NCEP/NCAR reanalyses, radiosonde observations at Singapore, and other observation-based datasets. Both reanalyses reproduce the QBO life cycle and its associated variability in the stratosphere reasonably well, except that some long-term changes are detected only in the NCEP/NCAR reanalysis. In order to separate QBO from variability on other time scales and to eliminate the long-term changes, a scale separation technique [Ensemble Empirical Mode Decomposition (EEMD)] is applied to the raw data. The QBO component of zonal wind anomalies at 30 hPa, extracted using the EEMD method, is defined as a QBO index. Using this index, the QBO life cycle composites of stratosphere and troposphere variables, as well as SSTA, are constructed and examined. The composite features in the stratosphere are generally consistent with previous investigations. The correlations between the QBO and tropical Pacific SSTA depend on the phase in a QBO life cycle. On average, cold (warm) SSTA peaks about half a year after the maximum westerlies (easterlies) at 30 hPa. The connection of the QBO with the troposphere seems to be associated with the differences of temperature anomalies between the stratosphere and troposphere. While the anomalies in the stratosphere propagate downward systematically, some anomalies in the troposphere develop and expand vertically. Therefore, it is possible that the temperature difference between the troposphere and stratosphere may alter the atmospheric stability and tropical deep convection, which modulates the Walker circulation and SSTA in the equatorial Pacific Ocean.

  9. Large-scale application of highly-diluted bacteria for Leptospirosis epidemic control.

    Science.gov (United States)

    Bracho, Gustavo; Varela, Enrique; Fernández, Rolando; Ordaz, Barbara; Marzoa, Natalia; Menéndez, Jorge; García, Luis; Gilling, Esperanza; Leyva, Richard; Rufín, Reynaldo; de la Torre, Rubén; Solis, Rosa L; Batista, Niurka; Borrero, Reinier; Campa, Concepción

    2010-07-01

    Leptospirosis is a zoonotic disease of major importance in the tropics where the incidence peaks in rainy seasons. Natural disasters represent a big challenge to Leptospirosis prevention strategies especially in endemic regions. Vaccination is an effective option but of reduced effectiveness in emergency situations. Homeoprophylactic interventions might help to control epidemics by using highly-diluted pathogens to induce protection in a short time scale. We report the results of a very large-scale homeoprophylaxis (HP) intervention against Leptospirosis in a dangerous epidemic situation in three provinces of Cuba in 2007. Forecast models were used to estimate possible trends of disease incidence. A homeoprophylactic formulation was prepared from dilutions of four circulating strains of Leptospirosis. This formulation was administered orally to 2.3 million persons at high risk in an epidemic in a region affected by natural disasters. The data from surveillance were used to measure the impact of the intervention by comparing with historical trends and non-intervention regions. After the homeoprophylactic intervention a significant decrease of the disease incidence was observed in the intervention regions. No such modifications were observed in non-intervention regions. In the intervention region the incidence of Leptospirosis fell below the historic median. This observation was independent of rainfall. The homeoprophylactic approach was associated with a large reduction of disease incidence and control of the epidemic. The results suggest the use of HP as a feasible tool for epidemic control, further research is warranted. 2010 Elsevier Ltd. All rights reserved.

  10. The Software Reliability of Large Scale Integration Circuit and Very Large Scale Integration Circuit

    OpenAIRE

    Artem Ganiyev; Jan Vitasek

    2010-01-01

    This article describes evaluation method of faultless function of large scale integration circuits (LSI) and very large scale integration circuits (VLSI). In the article there is a comparative analysis of factors which determine faultless of integrated circuits, analysis of already existing methods and model of faultless function evaluation of LSI and VLSI. The main part describes a proposed algorithm and program for analysis of fault rate in LSI and VLSI circuits.

  11. RESTRUCTURING OF THE LARGE-SCALE SPRINKLERS

    Directory of Open Access Journals (Sweden)

    Paweł Kozaczyk

    2016-09-01

    Full Text Available One of the best ways for agriculture to become independent from shortages of precipitation is irrigation. In the seventies and eighties of the last century a number of large-scale sprinklers in Wielkopolska was built. At the end of 1970’s in the Poznan province 67 sprinklers with a total area of 6400 ha were installed. The average size of the sprinkler reached 95 ha. In 1989 there were 98 sprinklers, and the area which was armed with them was more than 10 130 ha. The study was conducted on 7 large sprinklers with the area ranging from 230 to 520 hectares in 1986÷1998. After the introduction of the market economy in the early 90’s and ownership changes in agriculture, large-scale sprinklers have gone under a significant or total devastation. Land on the State Farms of the State Agricultural Property Agency has leased or sold and the new owners used the existing sprinklers to a very small extent. This involved a change in crop structure, demand structure and an increase in operating costs. There has also been a threefold increase in electricity prices. Operation of large-scale irrigation encountered all kinds of barriers in practice and limitations of system solutions, supply difficulties, high levels of equipment failure which is not inclined to rational use of available sprinklers. An effect of a vision of the local area was to show the current status of the remaining irrigation infrastructure. The adopted scheme for the restructuring of Polish agriculture was not the best solution, causing massive destruction of assets previously invested in the sprinkler system.

  12. Optical interconnect for large-scale systems

    Science.gov (United States)

    Dress, William

    2013-02-01

    This paper presents a switchless, optical interconnect module that serves as a node in a network of identical distribution modules for large-scale systems. Thousands to millions of hosts or endpoints may be interconnected by a network of such modules, avoiding the need for multi-level switches. Several common network topologies are reviewed and their scaling properties assessed. The concept of message-flow routing is discussed in conjunction with the unique properties enabled by the optical distribution module where it is shown how top-down software control (global routing tables, spanning-tree algorithms) may be avoided.

  13. Adaptive visualization for large-scale graph

    International Nuclear Information System (INIS)

    Nakamura, Hiroko; Shinano, Yuji; Ohzahata, Satoshi

    2010-01-01

    We propose an adoptive visualization technique for representing a large-scale hierarchical dataset within limited display space. A hierarchical dataset has nodes and links showing the parent-child relationship between the nodes. These nodes and links are described using graphics primitives. When the number of these primitives is large, it is difficult to recognize the structure of the hierarchical data because many primitives are overlapped within a limited region. To overcome this difficulty, we propose an adaptive visualization technique for hierarchical datasets. The proposed technique selects an appropriate graph style according to the nodal density in each area. (author)

  14. Neutrinos and large-scale structure

    International Nuclear Information System (INIS)

    Eisenstein, Daniel J.

    2015-01-01

    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. Puzzles of large scale structure and gravitation

    International Nuclear Information System (INIS)

    Sidharth, B.G.

    2006-01-01

    We consider the puzzle of cosmic voids bounded by two-dimensional structures of galactic clusters as also a puzzle pointed out by Weinberg: How can the mass of a typical elementary particle depend on a cosmic parameter like the Hubble constant? An answer to the first puzzle is proposed in terms of 'Scaled' Quantum Mechanical like behaviour which appears at large scales. The second puzzle can be answered by showing that the gravitational mass of an elementary particle has a Machian character (see Ahmed N. Cantorian small worked, Mach's principle and the universal mass network. Chaos, Solitons and Fractals 2004;21(4))

  16. Neutrinos and large-scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Eisenstein, Daniel J. [Daniel J. Eisenstein, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS #20, Cambridge, MA 02138 (United States)

    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.

  17. Concepts for Large Scale Hydrogen Production

    OpenAIRE

    Jakobsen, Daniel; Åtland, Vegar

    2016-01-01

    The objective of this thesis is to perform a techno-economic analysis of large-scale, carbon-lean hydrogen production in Norway, in order to evaluate various production methods and estimate a breakeven price level. Norway possesses vast energy resources and the export of oil and gas is vital to the country s economy. The results of this thesis indicate that hydrogen represents a viable, carbon-lean opportunity to utilize these resources, which can prove key in the future of Norwegian energy e...

  18. Stabilization Algorithms for Large-Scale Problems

    DEFF Research Database (Denmark)

    Jensen, Toke Koldborg

    2006-01-01

    The focus of the project is on stabilization of large-scale inverse problems where structured models and iterative algorithms are necessary for computing approximate solutions. For this purpose, we study various iterative Krylov methods and their abilities to produce regularized solutions. Some......-curve. This heuristic is implemented as a part of a larger algorithm which is developed in collaboration with G. Rodriguez and P. C. Hansen. Last, but not least, a large part of the project has, in different ways, revolved around the object-oriented Matlab toolbox MOORe Tools developed by PhD Michael Jacobsen. New...

  19. Large scale phononic metamaterials for seismic isolation

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  20. ECOLOGICAL RESEARCH IN THE LARGE-SCALE BIOSPHERE–ATMOSPHERE EXPERIMENT IN AMAZONIA: EARLY RESULTS.

    Science.gov (United States)

    M. Keller; A. Alencar; G. P. Asner; B. Braswell; M. Bustamente; E. Davidson; T. Feldpausch; E. Fern ndes; M. Goulden; P. Kabat; B. Kruijt; F. Luizao; S. Miller; D. Markewitz; A. D. Nobre; C. A. Nobre; N. Priante Filho; H. Rocha; P. Silva Dias; C von Randow; G. L. Vourlitis

    2004-01-01

    The Large-scale Biosphere–Atmosphere Experiment in Amazonia (LBA) is a multinational, interdisciplinary research program led by Brazil. Ecological studies in LBA focus on how tropical forest conversion, regrowth, and selective logging influence carbon storage, nutrient dynamics, trace gas fluxes, and the prospect for sustainable land use in the Amazon region. Early...

  1. Ecological research in the large-scale biosphere-atmosphere experiment in Amazonia: early results

    NARCIS (Netherlands)

    Keller, M.; Alencar, A.; Asner, G.P.; Braswell, B.; Bustamante, M.; Davidson, E.; Feldpausch, T.; Fernandes, E.; Goulden, M.; Kabat, P.; Kruijt, B.; Luizão, F.; Miller, S.; Markewitz, D.; Nobre, A.D.; Nobre, C.A.; Priante Filho, N.; Rocha, da H.; Silva Dias, P.; Randow, von C.; Vourlitis, G.L.

    2004-01-01

    The Large-scale Biosphere-Atmosphere Experiment in Amazonia (LBA) is a multinational, interdisciplinary research program led by Brazil. Ecological studies in LBA focus on how tropical forest conversion, regrowth, and selective logging influence carbon storage,. nutrient dynamics, trace gas fluxes,

  2. The role of large-scale, extratropical dynamics in climate change

    International Nuclear Information System (INIS)

    Shepherd, T.G.

    1994-02-01

    The climate modeling community has focused recently on improving our understanding of certain processes, such as cloud feedbacks and ocean circulation, that are deemed critical to climate-change prediction. Although attention to such processes is warranted, emphasis on these areas has diminished a general appreciation of the role played by the large-scale dynamics of the extratropical atmosphere. Lack of interest in extratropical dynamics may reflect the assumption that these dynamical processes are a non-problem as far as climate modeling is concerned, since general circulation models (GCMs) calculate motions on this scale from first principles. Nevertheless, serious shortcomings in our ability to understand and simulate large-scale dynamics exist. Partly due to a paucity of standard GCM diagnostic calculations of large-scale motions and their transports of heat, momentum, potential vorticity, and moisture, a comprehensive understanding of the role of large-scale dynamics in GCM climate simulations has not been developed. Uncertainties remain in our understanding and simulation of large-scale extratropical dynamics and their interaction with other climatic processes, such as cloud feedbacks, large-scale ocean circulation, moist convection, air-sea interaction and land-surface processes. To address some of these issues, the 17th Stanstead Seminar was convened at Bishop's University in Lennoxville, Quebec. The purpose of the Seminar was to promote discussion of the role of large-scale extratropical dynamics in global climate change. Abstracts of the talks are included in this volume. On the basis of these talks, several key issues emerged concerning large-scale extratropical dynamics and their climatic role. Individual records are indexed separately for the database

  3. The role of large-scale, extratropical dynamics in climate change

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, T.G. [ed.

    1994-02-01

    The climate modeling community has focused recently on improving our understanding of certain processes, such as cloud feedbacks and ocean circulation, that are deemed critical to climate-change prediction. Although attention to such processes is warranted, emphasis on these areas has diminished a general appreciation of the role played by the large-scale dynamics of the extratropical atmosphere. Lack of interest in extratropical dynamics may reflect the assumption that these dynamical processes are a non-problem as far as climate modeling is concerned, since general circulation models (GCMs) calculate motions on this scale from first principles. Nevertheless, serious shortcomings in our ability to understand and simulate large-scale dynamics exist. Partly due to a paucity of standard GCM diagnostic calculations of large-scale motions and their transports of heat, momentum, potential vorticity, and moisture, a comprehensive understanding of the role of large-scale dynamics in GCM climate simulations has not been developed. Uncertainties remain in our understanding and simulation of large-scale extratropical dynamics and their interaction with other climatic processes, such as cloud feedbacks, large-scale ocean circulation, moist convection, air-sea interaction and land-surface processes. To address some of these issues, the 17th Stanstead Seminar was convened at Bishop`s University in Lennoxville, Quebec. The purpose of the Seminar was to promote discussion of the role of large-scale extratropical dynamics in global climate change. Abstracts of the talks are included in this volume. On the basis of these talks, several key issues emerged concerning large-scale extratropical dynamics and their climatic role. Individual records are indexed separately for the database.

  4. Large-Scale Traveling Weather Systems in Mars’ Southern Extratropics

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2017-10-01

    Between late fall and early spring, Mars’ middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

  5. Large-Scale Traveling Weather Systems in Mars Southern Extratropics

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2017-01-01

    Between late fall and early spring, Mars' middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

  6. Dipolar modulation of Large-Scale Structure

    Science.gov (United States)

    Yoon, Mijin

    For the last two decades, we have seen a drastic development of modern cosmology based on various observations such as the cosmic microwave background (CMB), type Ia supernovae, and baryonic acoustic oscillations (BAO). These observational evidences have led us to a great deal of consensus on the cosmological model so-called LambdaCDM and tight constraints on cosmological parameters consisting the model. On the other hand, the advancement in cosmology relies on the cosmological principle: the universe is isotropic and homogeneous on large scales. Testing these fundamental assumptions is crucial and will soon become possible given the planned observations ahead. Dipolar modulation is the largest angular anisotropy of the sky, which is quantified by its direction and amplitude. We measured a huge dipolar modulation in CMB, which mainly originated from our solar system's motion relative to CMB rest frame. However, we have not yet acquired consistent measurements of dipolar modulations in large-scale structure (LSS), as they require large sky coverage and a number of well-identified objects. In this thesis, we explore measurement of dipolar modulation in number counts of LSS objects as a test of statistical isotropy. This thesis is based on two papers that were published in peer-reviewed journals. In Chapter 2 [Yoon et al., 2014], we measured a dipolar modulation in number counts of WISE matched with 2MASS sources. In Chapter 3 [Yoon & Huterer, 2015], we investigated requirements for detection of kinematic dipole in future surveys.

  7. Internationalization Measures in Large Scale Research Projects

    Science.gov (United States)

    Soeding, Emanuel; Smith, Nancy

    2017-04-01

    Internationalization measures in Large Scale Research Projects Large scale research projects (LSRP) often serve as flagships used by universities or research institutions to demonstrate their performance and capability to stakeholders and other interested parties. As the global competition among universities for the recruitment of the brightest brains has increased, effective internationalization measures have become hot topics for universities and LSRP alike. Nevertheless, most projects and universities are challenged with little experience on how to conduct these measures and make internationalization an cost efficient and useful activity. Furthermore, those undertakings permanently have to be justified with the Project PIs as important, valuable tools to improve the capacity of the project and the research location. There are a variety of measures, suited to support universities in international recruitment. These include e.g. institutional partnerships, research marketing, a welcome culture, support for science mobility and an effective alumni strategy. These activities, although often conducted by different university entities, are interlocked and can be very powerful measures if interfaced in an effective way. On this poster we display a number of internationalization measures for various target groups, identify interfaces between project management, university administration, researchers and international partners to work together, exchange information and improve processes in order to be able to recruit, support and keep the brightest heads to your project.

  8. Large scale integration of photovoltaics in cities

    International Nuclear Information System (INIS)

    Strzalka, Aneta; Alam, Nazmul; Duminil, Eric; Coors, Volker; Eicker, Ursula

    2012-01-01

    Highlights: ► We implement the photovoltaics on a large scale. ► We use three-dimensional modelling for accurate photovoltaic simulations. ► We consider the shadowing effect in the photovoltaic simulation. ► We validate the simulated results using detailed hourly measured data. - Abstract: For a large scale implementation of photovoltaics (PV) in the urban environment, building integration is a major issue. This includes installations on roof or facade surfaces with orientations that are not ideal for maximum energy production. To evaluate the performance of PV systems in urban settings and compare it with the building user’s electricity consumption, three-dimensional geometry modelling was combined with photovoltaic system simulations. As an example, the modern residential district of Scharnhauser Park (SHP) near Stuttgart/Germany was used to calculate the potential of photovoltaic energy and to evaluate the local own consumption of the energy produced. For most buildings of the district only annual electrical consumption data was available and only selected buildings have electronic metering equipment. The available roof area for one of these multi-family case study buildings was used for a detailed hourly simulation of the PV power production, which was then compared to the hourly measured electricity consumption. The results were extrapolated to all buildings of the analyzed area by normalizing them to the annual consumption data. The PV systems can produce 35% of the quarter’s total electricity consumption and half of this generated electricity is directly used within the buildings.

  9. Status: Large-scale subatmospheric cryogenic systems

    International Nuclear Information System (INIS)

    Peterson, T.

    1989-01-01

    In the late 1960's and early 1970's an interest in testing and operating RF cavities at 1.8K motivated the development and construction of four large (300 Watt) 1.8K refrigeration systems. in the past decade, development of successful superconducting RF cavities and interest in obtaining higher magnetic fields with the improved Niobium-Titanium superconductors has once again created interest in large-scale 1.8K refrigeration systems. The L'Air Liquide plant for Tore Supra is a recently commissioned 300 Watt 1.8K system which incorporates new technology, cold compressors, to obtain the low vapor pressure for low temperature cooling. CEBAF proposes to use cold compressors to obtain 5KW at 2.0K. Magnetic refrigerators of 10 Watt capacity or higher at 1.8K are now being developed. The state of the art of large-scale refrigeration in the range under 4K will be reviewed. 28 refs., 4 figs., 7 tabs

  10. Large-scale Intelligent Transporation Systems simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, T.; Canfield, T.; Hannebutte, U.; Levine, D.; Tentner, A.

    1995-06-01

    A prototype computer system has been developed which defines a high-level architecture for a large-scale, comprehensive, scalable simulation of an Intelligent Transportation System (ITS) capable of running on massively parallel computers and distributed (networked) computer systems. The prototype includes the modelling of instrumented ``smart`` vehicles with in-vehicle navigation units capable of optimal route planning and Traffic Management Centers (TMC). The TMC has probe vehicle tracking capabilities (display position and attributes of instrumented vehicles), and can provide 2-way interaction with traffic to provide advisories and link times. Both the in-vehicle navigation module and the TMC feature detailed graphical user interfaces to support human-factors studies. The prototype has been developed on a distributed system of networked UNIX computers but is designed to run on ANL`s IBM SP-X parallel computer system for large scale problems. A novel feature of our design is that vehicles will be represented by autonomus computer processes, each with a behavior model which performs independent route selection and reacts to external traffic events much like real vehicles. With this approach, one will be able to take advantage of emerging massively parallel processor (MPP) systems.

  11. Summer monsoon circulation and precipitation over the tropical Indian Ocean during ENSO in the NCEP climate forecast system

    Science.gov (United States)

    Chowdary, J. S.; Chaudhari, H. S.; Gnanaseelan, C.; Parekh, Anant; Suryachandra Rao, A.; Sreenivas, P.; Pokhrel, S.; Singh, P.

    2014-04-01

    This study investigates the El Niño Southern Oscillation (ENSO) teleconnections to tropical Indian Ocean (TIO) and their relationship with the Indian summer monsoon in the coupled general circulation model climate forecast system (CFS). The model shows good skill in simulating the impact of El Niño over the Indian Oceanic rim during its decay phase (the summer following peak phase of El Niño). Summer surface circulation patterns during the developing phase of El Niño are more influenced by local Sea Surface Temperature (SST) anomalies in the model unlike in observations. Eastern TIO cooling similar to that of Indian Ocean Dipole (IOD) is a dominant model feature in summer. This anomalous SST pattern therefore is attributed to the tendency of the model to simulate more frequent IOD events. On the other hand, in the model baroclinic response to the diabatic heating anomalies induced by the El Niño related warm SSTs is weak, resulting in reduced zonal extension of the Rossby wave response. This is mostly due to weak eastern Pacific summer time SST anomalies in the model during the developing phase of El Niño as compared to observations. Both eastern TIO cooling and weak SST warming in El Niño region combined together undermine the ENSO teleconnections to the TIO and south Asia regions. The model is able to capture the spatial patterns of SST, circulation and precipitation well during the decay phase of El Niño over the Indo-western Pacific including the typical spring asymmetric mode and summer basin-wide warming in TIO. The model simulated El Niño decay one or two seasons later, resulting long persistent warm SST and circulation anomalies mainly over the southwest TIO. In response to the late decay of El Niño, Ekman pumping shows two maxima over the southern TIO. In conjunction with this unrealistic Ekman pumping, westward propagating Rossby waves display two peaks, which play key role in the long-persistence of the TIO warming in the model (for more than a

  12. Interannual Tropical Rainfall Variability in General Circulation Model Simulations Associated with the Atmospheric Model Intercomparison Project.

    Science.gov (United States)

    Sperber, K. R.; Palmer, T. N.

    1996-11-01

    The interannual variability of rainfall over the Indian subcontinent, the African Sahel, and the Nordeste region of Brazil have been evaluated in 32 models for the period 1979-88 as part of the Atmospheric Model Intercomparison Project (AMIP). The interannual variations of Nordeste rainfall are the most readily captured, owing to the intimate link with Pacific and Atlantic sea surface temperatures. The precipitation variations over India and the Sahel are less well simulated. Additionally, an Indian monsoon wind shear index was calculated for each model. Evaluation of the interannual variability of a wind shear index over the summer monsoon region indicates that the models exhibit greater fidelity in capturing the large-scale dynamic fluctuations than the regional-scale rainfall variations. A rainfall/SST teleconnection quality control was used to objectively stratify model performance. Skill scores improved for those models that qualitatively simulated the observed rainfall/El Niño- Southern Oscillation SST correlation pattern. This subset of models also had a rainfall climatology that was in better agreement with observations, indicating a link between systematic model error and the ability to simulate interannual variations.A suite of six European Centre for Medium-Range Weather Forecasts (ECMWF) AMIP runs (differing only in their initial conditions) have also been examined. As observed, all-India rainfall was enhanced in 1988 relative to 1987 in each of these realizations. All-India rainfall variability during other years showed little or no predictability, possibly due to internal chaotic dynamics associated with intraseasonal monsoon fluctuations and/or unpredictable land surface process interactions. The interannual variations of Nordeste rainfall were best represented. The State University of New York at Albany/National Center for Atmospheric Research Genesis model was run in five initial condition realizations. In this model, the Nordeste rainfall

  13. Radiations: large scale monitoring in Japan

    International Nuclear Information System (INIS)

    Linton, M.; Khalatbari, A.

    2011-01-01

    As the consequences of radioactive leaks on their health are a matter of concern for Japanese people, a large scale epidemiological study has been launched by the Fukushima medical university. It concerns the two millions inhabitants of the Fukushima Prefecture. On the national level and with the support of public funds, medical care and follow-up, as well as systematic controls are foreseen, notably to check the thyroid of 360.000 young people less than 18 year old and of 20.000 pregnant women in the Fukushima Prefecture. Some measurements have already been performed on young children. Despite the sometimes rather low measures, and because they know that some parts of the area are at least as much contaminated as it was the case around Chernobyl, some people are reluctant to go back home

  14. Large-scale digitizer system, analog converters

    International Nuclear Information System (INIS)

    Althaus, R.F.; Lee, K.L.; Kirsten, F.A.; Wagner, L.J.

    1976-10-01

    Analog to digital converter circuits that are based on the sharing of common resources, including those which are critical to the linearity and stability of the individual channels, are described. Simplicity of circuit composition is valued over other more costly approaches. These are intended to be applied in a large-scale processing and digitizing system for use with high-energy physics detectors such as drift-chambers or phototube-scintillator arrays. Signal distribution techniques are of paramount importance in maintaining adequate signal-to-noise ratio. Noise in both amplitude and time-jitter senses is held sufficiently low so that conversions with 10-bit charge resolution and 12-bit time resolution are achieved

  15. Engineering management of large scale systems

    Science.gov (United States)

    Sanders, Serita; Gill, Tepper L.; Paul, Arthur S.

    1989-01-01

    The organization of high technology and engineering problem solving, has given rise to an emerging concept. Reasoning principles for integrating traditional engineering problem solving with system theory, management sciences, behavioral decision theory, and planning and design approaches can be incorporated into a methodological approach to solving problems with a long range perspective. Long range planning has a great potential to improve productivity by using a systematic and organized approach. Thus, efficiency and cost effectiveness are the driving forces in promoting the organization of engineering problems. Aspects of systems engineering that provide an understanding of management of large scale systems are broadly covered here. Due to the focus and application of research, other significant factors (e.g., human behavior, decision making, etc.) are not emphasized but are considered.

  16. Grid sensitivity capability for large scale structures

    Science.gov (United States)

    Nagendra, Gopal K.; Wallerstein, David V.

    1989-01-01

    The considerations and the resultant approach used to implement design sensitivity capability for grids into a large scale, general purpose finite element system (MSC/NASTRAN) are presented. The design variables are grid perturbations with a rather general linking capability. Moreover, shape and sizing variables may be linked together. The design is general enough to facilitate geometric modeling techniques for generating design variable linking schemes in an easy and straightforward manner. Test cases have been run and validated by comparison with the overall finite difference method. The linking of a design sensitivity capability for shape variables in MSC/NASTRAN with an optimizer would give designers a powerful, automated tool to carry out practical optimization design of real life, complicated structures.

  17. Large - scale Rectangular Ruler Automated Verification Device

    Science.gov (United States)

    Chen, Hao; Chang, Luping; Xing, Minjian; Xie, Xie

    2018-03-01

    This paper introduces a large-scale rectangular ruler automated verification device, which consists of photoelectric autocollimator and self-designed mechanical drive car and data automatic acquisition system. The design of mechanical structure part of the device refer to optical axis design, drive part, fixture device and wheel design. The design of control system of the device refer to hardware design and software design, and the hardware mainly uses singlechip system, and the software design is the process of the photoelectric autocollimator and the automatic data acquisition process. This devices can automated achieve vertical measurement data. The reliability of the device is verified by experimental comparison. The conclusion meets the requirement of the right angle test procedure.

  18. Large Scale Landform Mapping Using Lidar DEM

    Directory of Open Access Journals (Sweden)

    Türkay Gökgöz

    2015-08-01

    Full Text Available In this study, LIDAR DEM data was used to obtain a primary landform map in accordance with a well-known methodology. This primary landform map was generalized using the Focal Statistics tool (Majority, considering the minimum area condition in cartographic generalization in order to obtain landform maps at 1:1000 and 1:5000 scales. Both the primary and the generalized landform maps were verified visually with hillshaded DEM and an orthophoto. As a result, these maps provide satisfactory visuals of the landforms. In order to show the effect of generalization, the area of each landform in both the primary and the generalized maps was computed. Consequently, landform maps at large scales could be obtained with the proposed methodology, including generalization using LIDAR DEM.

  19. Constructing sites on a large scale

    DEFF Research Database (Denmark)

    Braae, Ellen Marie; Tietjen, Anne

    2011-01-01

    Since the 1990s, the regional scale has regained importance in urban and landscape design. In parallel, the focus in design tasks has shifted from master plans for urban extension to strategic urban transformation projects. A prominent example of a contemporary spatial development approach...... for setting the design brief in a large scale urban landscape in Norway, the Jaeren region around the city of Stavanger. In this paper, we first outline the methodological challenges and then present and discuss the proposed method based on our teaching experiences. On this basis, we discuss aspects...... is the IBA Emscher Park in the Ruhr area in Germany. Over a 10 years period (1988-1998), more than a 100 local transformation projects contributed to the transformation from an industrial to a post-industrial region. The current paradigm of planning by projects reinforces the role of the design disciplines...

  20. Large scale study of tooth enamel

    International Nuclear Information System (INIS)

    Bodart, F.; Deconninck, G.; Martin, M.T.

    Human tooth enamel contains traces of foreign elements. The presence of these elements is related to the history and the environment of the human body and can be considered as the signature of perturbations which occur during the growth of a tooth. A map of the distribution of these traces on a large scale sample of the population will constitute a reference for further investigations of environmental effects. On hundred eighty samples of teeth were first analyzed using PIXE, backscattering and nuclear reaction techniques. The results were analyzed using statistical methods. Correlations between O, F, Na, P, Ca, Mn, Fe, Cu, Zn, Pb and Sr were observed and cluster analysis was in progress. The techniques described in the present work have been developed in order to establish a method for the exploration of very large samples of the Belgian population. (author)

  1. Testing Einstein's Gravity on Large Scales

    Science.gov (United States)

    Prescod-Weinstein, Chandra

    2011-01-01

    A little over a decade has passed since two teams studying high redshift Type Ia supernovae announced the discovery that the expansion of the universe was accelerating. After all this time, we?re still not sure how cosmic acceleration fits into the theory that tells us about the large-scale universe: General Relativity (GR). As part of our search for answers, we have been forced to question GR itself. But how will we test our ideas? We are fortunate enough to be entering the era of precision cosmology, where the standard model of gravity can be subjected to more rigorous testing. Various techniques will be employed over the next decade or two in the effort to better understand cosmic acceleration and the theory behind it. In this talk, I will describe cosmic acceleration, current proposals to explain it, and weak gravitational lensing, an observational effect that allows us to do the necessary precision cosmology.

  2. Large-Scale Astrophysical Visualization on Smartphones

    Science.gov (United States)

    Becciani, U.; Massimino, P.; Costa, A.; Gheller, C.; Grillo, A.; Krokos, M.; Petta, C.

    2011-07-01

    Nowadays digital sky surveys and long-duration, high-resolution numerical simulations using high performance computing and grid systems produce multidimensional astrophysical datasets in the order of several Petabytes. Sharing visualizations of such datasets within communities and collaborating research groups is of paramount importance for disseminating results and advancing astrophysical research. Moreover educational and public outreach programs can benefit greatly from novel ways of presenting these datasets by promoting understanding of complex astrophysical processes, e.g., formation of stars and galaxies. We have previously developed VisIVO Server, a grid-enabled platform for high-performance large-scale astrophysical visualization. This article reviews the latest developments on VisIVO Web, a custom designed web portal wrapped around VisIVO Server, then introduces VisIVO Smartphone, a gateway connecting VisIVO Web and data repositories for mobile astrophysical visualization. We discuss current work and summarize future developments.

  3. Large-scale sequential quadratic programming algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Eldersveld, S.K.

    1992-09-01

    The problem addressed is the general nonlinear programming problem: finding a local minimizer for a nonlinear function subject to a mixture of nonlinear equality and inequality constraints. The methods studied are in the class of sequential quadratic programming (SQP) algorithms, which have previously proved successful for problems of moderate size. Our goal is to devise an SQP algorithm that is applicable to large-scale optimization problems, using sparse data structures and storing less curvature information but maintaining the property of superlinear convergence. The main features are: 1. The use of a quasi-Newton approximation to the reduced Hessian of the Lagrangian function. Only an estimate of the reduced Hessian matrix is required by our algorithm. The impact of not having available the full Hessian approximation is studied and alternative estimates are constructed. 2. The use of a transformation matrix Q. This allows the QP gradient to be computed easily when only the reduced Hessian approximation is maintained. 3. The use of a reduced-gradient form of the basis for the null space of the working set. This choice of basis is more practical than an orthogonal null-space basis for large-scale problems. The continuity condition for this choice is proven. 4. The use of incomplete solutions of quadratic programming subproblems. Certain iterates generated by an active-set method for the QP subproblem are used in place of the QP minimizer to define the search direction for the nonlinear problem. An implementation of the new algorithm has been obtained by modifying the code MINOS. Results and comparisons with MINOS and NPSOL are given for the new algorithm on a set of 92 test problems.

  4. Nature of global large-scale sea level variability in relation to atmospheric forcing: A modeling study

    Science.gov (United States)

    Fukumori, Ichiro; Raghunath, Ramanujam; Fu, Lee-Lueng

    1998-03-01

    The relation between large-scale sea level variability and ocean circulation is studied using a numerical model. A global primitive equation model of the ocean is forced by daily winds and climatological heat fluxes corresponding to the period from January 1992 to January 1994. The physical nature of sea level's temporal variability from periods of days to a year is examined on the basis of spectral analyses of model results and comparisons with satellite altimetry and tide gauge measurements. The study elucidates and diagnoses the inhomogeneous physics of sea level change in space and frequency domain. At midlatitudes, large-scale sea level variability is primarily due to steric changes associated with the seasonal heating and cooling cycle of the surface layer. In comparison, changes in the tropics and high latitudes are mainly wind driven. Wind-driven variability exhibits a strong latitudinal dependence in itself. Wind-driven changes are largely baroclinic in the tropics but barotropic at higher latitudes. Baroclinic changes are dominated by the annual harmonic of the first baroclinic mode and is largest off the equator; variabilities associated with equatorial waves are smaller in comparison. Wind-driven barotropic changes exhibit a notable enhancement over several abyssal plains in the Southern Ocean, which is likely due to resonant planetary wave modes in basins semienclosed by discontinuities in potential vorticity. Otherwise, barotropic sea level changes are typically dominated by high frequencies with as much as half the total variance in periods shorter than 20 days, reflecting the frequency spectra of wind stress curl. Implications of the findings with regards to analyzing observations and data assimilation are discussed.

  5. Polynomial Chaos–Based Bayesian Inference of K-Profile Parameterization in a General Circulation Model of the Tropical Pacific

    KAUST Repository

    Sraj, Ihab

    2016-08-26

    The authors present a polynomial chaos (PC)-based Bayesian inference method for quantifying the uncertainties of the K-profile parameterization (KPP) within the MIT general circulation model (MITgcm) of the tropical Pacific. The inference of the uncertain parameters is based on a Markov chain Monte Carlo (MCMC) scheme that utilizes a newly formulated test statistic taking into account the different components representing the structures of turbulent mixing on both daily and seasonal time scales in addition to the data quality, and filters for the effects of parameter perturbations over those as a result of changes in the wind. To avoid the prohibitive computational cost of integrating the MITgcm model at each MCMC iteration, a surrogate model for the test statistic using the PC method is built. Because of the noise in the model predictions, a basis-pursuit-denoising (BPDN) compressed sensing approach is employed to determine the PC coefficients of a representative surrogate model. The PC surrogate is then used to evaluate the test statistic in the MCMC step for sampling the posterior of the uncertain parameters. Results of the posteriors indicate good agreement with the default values for two parameters of the KPP model, namely the critical bulk and gradient Richardson numbers; while the posteriors of the remaining parameters were barely informative. © 2016 American Meteorological Society.

  6. A Python Implementation of an Intermediate-Level Tropical Circulation Model and Implications for How Modeling Science is Done

    Science.gov (United States)

    Lin, J. W. B.

    2015-12-01

    Historically, climate models have been developed incrementally and in compiled languages like Fortran. While the use of legacy compiledlanguages results in fast, time-tested code, the resulting model is limited in its modularity and cannot take advantage of functionalityavailable with modern computer languages. Here we describe an effort at using the open-source, object-oriented language Pythonto create more flexible climate models: the package qtcm, a Python implementation of the intermediate-level Neelin-Zeng Quasi-Equilibrium Tropical Circulation model (QTCM1) of the atmosphere. The qtcm package retains the core numerics of QTCM1, written in Fortran, to optimize model performance but uses Python structures and utilities to wrap the QTCM1 Fortran routines and manage model execution. The resulting "mixed language" modeling package allows order and choice of subroutine execution to be altered at run time, and model analysis and visualization to be integrated in interactively with model execution at run time. This flexibility facilitates more complex scientific analysis using less complex code than would be possible using traditional languages alone and provides tools to transform the traditional "formulate hypothesis → write and test code → run model → analyze results" sequence into a feedback loop that can be executed automatically by the computer.

  7. Large-scale stochasticity in Hamiltonian systems

    International Nuclear Information System (INIS)

    Escande, D.F.

    1982-01-01

    Large scale stochasticity (L.S.S.) in Hamiltonian systems is defined on the paradigm Hamiltonian H(v,x,t) =v 2 /2-M cos x-P cos k(x-t) which describes the motion of one particle in two electrostatic waves. A renormalization transformation Tsub(r) is described which acts as a microscope that focusses on a given KAM (Kolmogorov-Arnold-Moser) torus in phase space. Though approximate, Tsub(r) yields the threshold of L.S.S. in H with an error of 5-10%. The universal behaviour of KAM tori is predicted: for instance the scale invariance of KAM tori and the critical exponent of the Lyapunov exponent of Cantori. The Fourier expansion of KAM tori is computed and several conjectures by L. Kadanoff and S. Shenker are proved. Chirikov's standard mapping for stochastic layers is derived in a simpler way and the width of the layers is computed. A simpler renormalization scheme for these layers is defined. A Mathieu equation for describing the stability of a discrete family of cycles is derived. When combined with Tsub(r), it allows to prove the link between KAM tori and nearby cycles, conjectured by J. Greene and, in particular, to compute the mean residue of a torus. The fractal diagrams defined by G. Schmidt are computed. A sketch of a methodology for computing the L.S.S. threshold in any two-degree-of-freedom Hamiltonian system is given. (Auth.)

  8. Large scale molecular simulations of nanotoxicity.

    Science.gov (United States)

    Jimenez-Cruz, Camilo A; Kang, Seung-gu; Zhou, Ruhong

    2014-01-01

    The widespread use of nanomaterials in biomedical applications has been accompanied by an increasing interest in understanding their interactions with tissues, cells, and biomolecules, and in particular, on how they might affect the integrity of cell membranes and proteins. In this mini-review, we present a summary of some of the recent studies on this important subject, especially from the point of view of large scale molecular simulations. The carbon-based nanomaterials and noble metal nanoparticles are the main focus, with additional discussions on quantum dots and other nanoparticles as well. The driving forces for adsorption of fullerenes, carbon nanotubes, and graphene nanosheets onto proteins or cell membranes are found to be mainly hydrophobic interactions and the so-called π-π stacking (between aromatic rings), while for the noble metal nanoparticles the long-range electrostatic interactions play a bigger role. More interestingly, there are also growing evidences showing that nanotoxicity can have implications in de novo design of nanomedicine. For example, the endohedral metallofullerenol Gd@C₈₂(OH)₂₂ is shown to inhibit tumor growth and metastasis by inhibiting enzyme MMP-9, and graphene is illustrated to disrupt bacteria cell membranes by insertion/cutting as well as destructive extraction of lipid molecules. These recent findings have provided a better understanding of nanotoxicity at the molecular level and also suggested therapeutic potential by using the cytotoxicity of nanoparticles against cancer or bacteria cells. © 2014 Wiley Periodicals, Inc.

  9. Large-scale tides in general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Ip, Hiu Yan; Schmidt, Fabian, E-mail: iphys@mpa-garching.mpg.de, E-mail: fabians@mpa-garching.mpg.de [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany)

    2017-02-01

    Density perturbations in cosmology, i.e. spherically symmetric adiabatic perturbations of a Friedmann-Lemaȋtre-Robertson-Walker (FLRW) spacetime, are locally exactly equivalent to a different FLRW solution, as long as their wavelength is much larger than the sound horizon of all fluid components. This fact is known as the 'separate universe' paradigm. However, no such relation is known for anisotropic adiabatic perturbations, which correspond to an FLRW spacetime with large-scale tidal fields. Here, we provide a closed, fully relativistic set of evolutionary equations for the nonlinear evolution of such modes, based on the conformal Fermi (CFC) frame. We show explicitly that the tidal effects are encoded by the Weyl tensor, and are hence entirely different from an anisotropic Bianchi I spacetime, where the anisotropy is sourced by the Ricci tensor. In order to close the system, certain higher derivative terms have to be dropped. We show that this approximation is equivalent to the local tidal approximation of Hui and Bertschinger [1]. We also show that this very simple set of equations matches the exact evolution of the density field at second order, but fails at third and higher order. This provides a useful, easy-to-use framework for computing the fully relativistic growth of structure at second order.

  10. Food appropriation through large scale land acquisitions

    International Nuclear Information System (INIS)

    Cristina Rulli, Maria; D’Odorico, Paolo

    2014-01-01

    The increasing demand for agricultural products and the uncertainty of international food markets has recently drawn the attention of governments and agribusiness firms toward investments in productive agricultural land, mostly in the developing world. The targeted countries are typically located in regions that have remained only marginally utilized because of lack of modern technology. It is expected that in the long run large scale land acquisitions (LSLAs) for commercial farming will bring the technology required to close the existing crops yield gaps. While the extent of the acquired land and the associated appropriation of freshwater resources have been investigated in detail, the amount of food this land can produce and the number of people it could feed still need to be quantified. Here we use a unique dataset of land deals to provide a global quantitative assessment of the rates of crop and food appropriation potentially associated with LSLAs. We show how up to 300–550 million people could be fed by crops grown in the acquired land, should these investments in agriculture improve crop production and close the yield gap. In contrast, about 190–370 million people could be supported by this land without closing of the yield gap. These numbers raise some concern because the food produced in the acquired land is typically exported to other regions, while the target countries exhibit high levels of malnourishment. Conversely, if used for domestic consumption, the crops harvested in the acquired land could ensure food security to the local populations. (letter)

  11. Large Scale EOF Analysis of Climate Data

    Science.gov (United States)

    Prabhat, M.; Gittens, A.; Kashinath, K.; Cavanaugh, N. R.; Mahoney, M.

    2016-12-01

    We present a distributed approach towards extracting EOFs from 3D climate data. We implement the method in Apache Spark, and process multi-TB sized datasets on O(1000-10,000) cores. We apply this method to latitude-weighted ocean temperature data from CSFR, a 2.2 terabyte-sized data set comprising ocean and subsurface reanalysis measurements collected at 41 levels in the ocean, at 6 hour intervals over 31 years. We extract the first 100 EOFs of this full data set and compare to the EOFs computed simply on the surface temperature field. Our analyses provide evidence of Kelvin and Rossy waves and components of large-scale modes of oscillation including the ENSO and PDO that are not visible in the usual SST EOFs. Further, they provide information on the the most influential parts of the ocean, such as the thermocline, that exist below the surface. Work is ongoing to understand the factors determining the depth-varying spatial patterns observed in the EOFs. We will experiment with weighting schemes to appropriately account for the differing depths of the observations. We also plan to apply the same distributed approach to analysis of analysis of 3D atmospheric climatic data sets, including multiple variables. Because the atmosphere changes on a quicker time-scale than the ocean, we expect that the results will demonstrate an even greater advantage to computing 3D EOFs in lieu of 2D EOFs.

  12. Mirror dark matter and large scale structure

    International Nuclear Information System (INIS)

    Ignatiev, A.Yu.; Volkas, R.R.

    2003-01-01

    Mirror matter is a dark matter candidate. In this paper, we reexamine the linear regime of density perturbation growth in a universe containing mirror dark matter. Taking adiabatic scale-invariant perturbations as the input, we confirm that the resulting processed power spectrum is richer than for the more familiar cases of cold, warm and hot dark matter. The new features include a maximum at a certain scale λ max , collisional damping below a smaller characteristic scale λ S ' , with oscillatory perturbations between the two. These scales are functions of the fundamental parameters of the theory. In particular, they decrease for decreasing x, the ratio of the mirror plasma temperature to that of the ordinary. For x∼0.2, the scale λ max becomes galactic. Mirror dark matter therefore leads to bottom-up large scale structure formation, similar to conventional cold dark matter, for x(less-or-similar sign)0.2. Indeed, the smaller the value of x, the closer mirror dark matter resembles standard cold dark matter during the linear regime. The differences pertain to scales smaller than λ S ' in the linear regime, and generally in the nonlinear regime because mirror dark matter is chemically complex and to some extent dissipative. Lyman-α forest data and the early reionization epoch established by WMAP may hold the key to distinguishing mirror dark matter from WIMP-style cold dark matter

  13. Tropical intraseasonal rainfall variability in the CFSR

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiande [I.M. System Group Inc. at NOAA/NCEP/EMC, Camp Springs, MD (United States); Wang, Wanqiu [NOAA/NCEP/CPC, Camp Springs, MD (United States); Fu, Xiouhua [University of Hawaii at Manoa, IPRC, SOEST, Honolulu, HI (United States); Seo, Kyong-Hwan [Pusan National University, Department of Atmospheric Sciences, Busan (Korea, Republic of)

    2012-06-15

    While large-scale circulation fields from atmospheric reanalyses have been widely used to study the tropical intraseasonal variability, rainfall variations from the reanalyses are less focused. Because of the sparseness of in situ observations available in the tropics and strong coupling between convection and large-scale circulation, the accuracy of tropical rainfall from the reanalyses not only measures the quality of reanalysis rainfall but is also to some extent indicative of the accuracy of the circulations fields. This study analyzes tropical intraseasonal rainfall variability in the recently completed NCEP Climate Forecast System Reanalysis (CFSR) and its comparison with the widely used NCEP/NCAR reanalysis (R1) and NCEP/DOE reanalysis (R2). The R1 produces too weak rainfall variability while the R2 generates too strong westward propagation. Compared with the R1 and R2, the CFSR produces greatly improved tropical intraseasonal rainfall variability with the dominance of eastward propagation and more realistic amplitude. An analysis of the relationship between rainfall and large-scale fields using composites based on Madden-Julian Oscillation (MJO) events shows that, in all three NCEP reanalyses, the moisture convergence leading the rainfall maximum is near the surface in the western Pacific but is above 925 hPa in the eastern Indian Ocean. However, the CFSR produces the strongest large-scale convergence and the rainfall from CFSR lags the column integrated precipitable water by 1 or 2 days while R1 and R2 rainfall tends to lead the respective precipitable water. Diabatic heating related to the MJO variability in the CFSR is analyzed and compared with that derived from large-scale fields. It is found that the amplitude of CFSR-produced total heating anomalies is smaller than that of the derived. Rainfall variability from the other two recently produced reanalyses, the ECMWF Re-Analysis Interim (ERAI), and the Modern Era Retrospective-analysis for Research and

  14. Sensitivity technologies for large scale simulation

    International Nuclear Information System (INIS)

    Collis, Samuel Scott; Bartlett, Roscoe Ainsworth; Smith, Thomas Michael; Heinkenschloss, Matthias; Wilcox, Lucas C.; Hill, Judith C.; Ghattas, Omar; Berggren, Martin Olof; Akcelik, Volkan; Ober, Curtis Curry; van Bloemen Waanders, Bart Gustaaf; Keiter, Eric Richard

    2005-01-01

    Sensitivity analysis is critically important to numerous analysis algorithms, including large scale optimization, uncertainty quantification,reduced order modeling, and error estimation. Our research focused on developing tools, algorithms and standard interfaces to facilitate the implementation of sensitivity type analysis into existing code and equally important, the work was focused on ways to increase the visibility of sensitivity analysis. We attempt to accomplish the first objective through the development of hybrid automatic differentiation tools, standard linear algebra interfaces for numerical algorithms, time domain decomposition algorithms and two level Newton methods. We attempt to accomplish the second goal by presenting the results of several case studies in which direct sensitivities and adjoint methods have been effectively applied, in addition to an investigation of h-p adaptivity using adjoint based a posteriori error estimation. A mathematical overview is provided of direct sensitivities and adjoint methods for both steady state and transient simulations. Two case studies are presented to demonstrate the utility of these methods. A direct sensitivity method is implemented to solve a source inversion problem for steady state internal flows subject to convection diffusion. Real time performance is achieved using novel decomposition into offline and online calculations. Adjoint methods are used to reconstruct initial conditions of a contamination event in an external flow. We demonstrate an adjoint based transient solution. In addition, we investigated time domain decomposition algorithms in an attempt to improve the efficiency of transient simulations. Because derivative calculations are at the root of sensitivity calculations, we have developed hybrid automatic differentiation methods and implemented this approach for shape optimization for gas dynamics using the Euler equations. The hybrid automatic differentiation method was applied to a first

  15. GPU-based large-scale visualization

    KAUST Repository

    Hadwiger, Markus

    2013-11-19

    Recent advances in image and volume acquisition as well as computational advances in simulation have led to an explosion of the amount of data that must be visualized and analyzed. Modern techniques combine the parallel processing power of GPUs with out-of-core methods and data streaming to enable the interactive visualization of giga- and terabytes of image and volume data. A major enabler for interactivity is making both the computational and the visualization effort proportional to the amount of data that is actually visible on screen, decoupling it from the full data size. This leads to powerful display-aware multi-resolution techniques that enable the visualization of data of almost arbitrary size. The course consists of two major parts: An introductory part that progresses from fundamentals to modern techniques, and a more advanced part that discusses details of ray-guided volume rendering, novel data structures for display-aware visualization and processing, and the remote visualization of large online data collections. You will learn how to develop efficient GPU data structures and large-scale visualizations, implement out-of-core strategies and concepts such as virtual texturing that have only been employed recently, as well as how to use modern multi-resolution representations. These approaches reduce the GPU memory requirements of extremely large data to a working set size that fits into current GPUs. You will learn how to perform ray-casting of volume data of almost arbitrary size and how to render and process gigapixel images using scalable, display-aware techniques. We will describe custom virtual texturing architectures as well as recent hardware developments in this area. We will also describe client/server systems for distributed visualization, on-demand data processing and streaming, and remote visualization. We will describe implementations using OpenGL as well as CUDA, exploiting parallelism on GPUs combined with additional asynchronous

  16. Large Scale Self-Organizing Information Distribution System

    National Research Council Canada - National Science Library

    Low, Steven

    2005-01-01

    This project investigates issues in "large-scale" networks. Here "large-scale" refers to networks with large number of high capacity nodes and transmission links, and shared by a large number of users...

  17. Distributed large-scale dimensional metrology new insights

    CERN Document Server

    Franceschini, Fiorenzo; Maisano, Domenico

    2011-01-01

    Focuses on the latest insights into and challenges of distributed large scale dimensional metrology Enables practitioners to study distributed large scale dimensional metrology independently Includes specific examples of the development of new system prototypes

  18. The Effect of Large Scale Salinity Gradient on Langmuir Turbulence

    Science.gov (United States)

    Fan, Y.; Jarosz, E.; Yu, Z.; Jensen, T.; Sullivan, P. P.; Liang, J.

    2017-12-01

    Langmuir circulation (LC) is believed to be one of the leading order causes of turbulent mixing in the upper ocean. It is important for momentum and heat exchange across the mixed layer (ML) and directly impact the dynamics and thermodynamics in the upper ocean and lower atmosphere including the vertical distributions of chemical, biological, optical, and acoustic properties. Based on Craik and Leibovich (1976) theory, large eddy simulation (LES) models have been developed to simulate LC in the upper ocean, yielding new insights that could not be obtained from field observations and turbulent closure models. Due its high computational cost, LES models are usually limited to small domain sizes and cannot resolve large-scale flows. Furthermore, most LES models used in the LC simulations use periodic boundary conditions in the horizontal direction, which assumes the physical properties (i.e. temperature and salinity) and expected flow patterns in the area of interest are of a periodically repeating nature so that the limited small LES domain is representative for the larger area. Using periodic boundary condition can significantly reduce computational effort in problems, and it is a good assumption for isotropic shear turbulence. However, LC is anisotropic (McWilliams et al 1997) and was observed to be modulated by crosswind tidal currents (Kukulka et al 2011). Using symmetrical domains, idealized LES studies also indicate LC could interact with oceanic fronts (Hamlington et al 2014) and standing internal waves (Chini and Leibovich, 2005). The present study expands our previous LES modeling investigations of Langmuir turbulence to the real ocean conditions with large scale environmental motion that features fresh water inflow into the study region. Large scale gradient forcing is introduced to the NCAR LES model through scale separation analysis. The model is applied to a field observation in the Gulf of Mexico in July, 2016 when the measurement site was impacted by

  19. Effect of the tropical Pacific and Indian Ocean warming since the late 1970s on wintertime Northern Hemispheric atmospheric circulation and East Asian climate interdecadal changes

    Science.gov (United States)

    Chu, Cuijiao; Yang, Xiu-Qun; Sun, Xuguang; Yang, Dejian; Jiang, Yiquan; Feng, Tao; Liang, Jin

    2018-04-01

    Observation reveals that the tropical Pacific-Indian Ocean (TPIO) has experienced a pronounced interdecadal warming since the end of the 1970s. Meanwhile, the wintertime midlatitude Northern Hemispheric atmospheric circulation and East Asian climate have also undergone substantial interdecadal changes. The effect of the TPIO warming on these interdecadal changes are identified by a suite of AMIP-type atmospheric general circulation model experiments in which the model is integrated from September 1948 to December 1999 with prescribed historical, observed realistic sea surface temperature (SST) in a specific region and climatological SST elsewhere. Results show that the TPIO warming reproduces quite well the observed Northern Hemispheric wintertime interdecadal changes, suggesting that these interdecadal changes primarily originate from the TPIO warming. However, each sub-region of TPIO has its own distinct contribution. Comparatively, the tropical central-eastern Pacific (TCEP) and tropical western Pacific (TWP) warming makes dominant contributions to the observed positive-phase PNA-like interdecadal anomaly over the North Pacific sector, while the tropical Indian Ocean (TIO) warming tends to cancel these contributions. Meanwhile, the TIO and TWP warming makes dominant contributions to the observed positive NAO-like interdecadal anomaly over the North Atlantic sector as well as the interdecadal anomalies over the Eurasian sector, although the TWP warming's contribution is relatively small. These remote responses are directly attributed to the TPIO warming-induced tropical convection, rainfall and diabatic heating increases, in which the TIO warming has the most significant effect. Moreover, the TPIO warming excites a Gill-type pattern anomaly over the tropical western Pacific, with a low-level anticyclonic circulation anomaly over the Philippine Sea. Of three sub-regions, the TIO warming dominates such a pattern, although the TWP warming tends to cancel this effect

  20. Probes of large-scale structure in the Universe

    International Nuclear Information System (INIS)

    Suto, Yasushi; Gorski, K.; Juszkiewicz, R.; Silk, J.

    1988-01-01

    Recent progress in observational techniques has made it possible to confront quantitatively various models for the large-scale structure of the Universe with detailed observational data. We develop a general formalism to show that the gravitational instability theory for the origin of large-scale structure is now capable of critically confronting observational results on cosmic microwave background radiation angular anisotropies, large-scale bulk motions and large-scale clumpiness in the galaxy counts. (author)

  1. Large scale dynamics of protoplanetary discs

    Science.gov (United States)

    Béthune, William

    2017-08-01

    Planets form in the gaseous and dusty disks orbiting young stars. These protoplanetary disks are dispersed in a few million years, being accreted onto the central star or evaporated into the interstellar medium. To explain the observed accretion rates, it is commonly assumed that matter is transported through the disk by turbulence, although the mechanism sustaining turbulence is uncertain. On the other side, irradiation by the central star could heat up the disk surface and trigger a photoevaporative wind, but thermal effects cannot account for the observed acceleration and collimation of the wind into a narrow jet perpendicular to the disk plane. Both issues can be solved if the disk is sensitive to magnetic fields. Weak fields lead to the magnetorotational instability, whose outcome is a state of sustained turbulence. Strong fields can slow down the disk, causing it to accrete while launching a collimated wind. However, the coupling between the disk and the neutral gas is done via electric charges, each of which is outnumbered by several billion neutral molecules. The imperfect coupling between the magnetic field and the neutral gas is described in terms of "non-ideal" effects, introducing new dynamical behaviors. This thesis is devoted to the transport processes happening inside weakly ionized and weakly magnetized accretion disks; the role of microphysical effects on the large-scale dynamics of the disk is of primary importance. As a first step, I exclude the wind and examine the impact of non-ideal effects on the turbulent properties near the disk midplane. I show that the flow can spontaneously organize itself if the ionization fraction is low enough; in this case, accretion is halted and the disk exhibits axisymmetric structures, with possible consequences on planetary formation. As a second step, I study the launching of disk winds via a global model of stratified disk embedded in a warm atmosphere. This model is the first to compute non-ideal effects from

  2. Large-Scale Spacecraft Fire Safety Tests

    Science.gov (United States)

    Urban, David; Ruff, Gary A.; Ferkul, Paul V.; Olson, Sandra; Fernandez-Pello, A. Carlos; T'ien, James S.; Torero, Jose L.; Cowlard, Adam J.; Rouvreau, Sebastien; Minster, Olivier; hide

    2014-01-01

    An international collaborative program is underway to address open issues in spacecraft fire safety. Because of limited access to long-term low-gravity conditions and the small volume generally allotted for these experiments, there have been relatively few experiments that directly study spacecraft fire safety under low-gravity conditions. Furthermore, none of these experiments have studied sample sizes and environment conditions typical of those expected in a spacecraft fire. The major constraint has been the size of the sample, with prior experiments limited to samples of the order of 10 cm in length and width or smaller. This lack of experimental data forces spacecraft designers to base their designs and safety precautions on 1-g understanding of flame spread, fire detection, and suppression. However, low-gravity combustion research has demonstrated substantial differences in flame behavior in low-gravity. This, combined with the differences caused by the confined spacecraft environment, necessitates practical scale spacecraft fire safety research to mitigate risks for future space missions. To address this issue, a large-scale spacecraft fire experiment is under development by NASA and an international team of investigators. This poster presents the objectives, status, and concept of this collaborative international project (Saffire). The project plan is to conduct fire safety experiments on three sequential flights of an unmanned ISS re-supply spacecraft (the Orbital Cygnus vehicle) after they have completed their delivery of cargo to the ISS and have begun their return journeys to earth. On two flights (Saffire-1 and Saffire-3), the experiment will consist of a flame spread test involving a meter-scale sample ignited in the pressurized volume of the spacecraft and allowed to burn to completion while measurements are made. On one of the flights (Saffire-2), 9 smaller (5 x 30 cm) samples will be tested to evaluate NASAs material flammability screening tests

  3. Large-scale fuel cycle centres

    International Nuclear Information System (INIS)

    Smiley, S.H.; Black, K.M.

    1977-01-01

    The US Nuclear Regulatory Commission (NRC) has considered the nuclear energy centre concept for fuel cycle plants in the Nuclear Energy Centre Site Survey 1975 (NECSS-75) Rep. No. NUREG-0001, an important study mandated by the US Congress in the Energy Reorganization Act of 1974 which created the NRC. For this study, the NRC defined fuel cycle centres as consisting of fuel reprocessing and mixed-oxide fuel fabrication plants, and optional high-level waste and transuranic waste management facilities. A range of fuel cycle centre sizes corresponded to the fuel throughput of power plants with a total capacity of 50,000-300,000MW(e). The types of fuel cycle facilities located at the fuel cycle centre permit the assessment of the role of fuel cycle centres in enhancing the safeguard of strategic special nuclear materials - plutonium and mixed oxides. Siting fuel cycle centres presents a smaller problem than siting reactors. A single reprocessing plant of the scale projected for use in the USA (1500-2000t/a) can reprocess fuel from reactors producing 50,000-65,000MW(e). Only two or three fuel cycle centres of the upper limit size considered in the NECSS-75 would be required in the USA by the year 2000. The NECSS-75 fuel cycle centre evaluation showed that large-scale fuel cycle centres present no real technical siting difficulties from a radiological effluent and safety standpoint. Some construction economies may be achievable with fuel cycle centres, which offer opportunities to improve waste-management systems. Combined centres consisting of reactors and fuel reprocessing and mixed-oxide fuel fabrication plants were also studied in the NECSS. Such centres can eliminate shipment not only of Pu but also mixed-oxide fuel. Increased fuel cycle costs result from implementation of combined centres unless the fuel reprocessing plants are commercial-sized. Development of Pu-burning reactors could reduce any economic penalties of combined centres. The need for effective fissile

  4. Large-scale climatic anomalies affect marine predator foraging behaviour and demography

    Science.gov (United States)

    Bost, Charles A.; Cotté, Cedric; Terray, Pascal; Barbraud, Christophe; Bon, Cécile; Delord, Karine; Gimenez, Olivier; Handrich, Yves; Naito, Yasuhiko; Guinet, Christophe; Weimerskirch, Henri

    2015-10-01

    Determining the links between the behavioural and population responses of wild species to environmental variations is critical for understanding the impact of climate variability on ecosystems. Using long-term data sets, we show how large-scale climatic anomalies in the Southern Hemisphere affect the foraging behaviour and population dynamics of a key marine predator, the king penguin. When large-scale subtropical dipole events occur simultaneously in both subtropical Southern Indian and Atlantic Oceans, they generate tropical anomalies that shift the foraging zone southward. Consequently the distances that penguins foraged from the colony and their feeding depths increased and the population size decreased. This represents an example of a robust and fast impact of large-scale climatic anomalies affecting a marine predator through changes in its at-sea behaviour and demography, despite lack of information on prey availability. Our results highlight a possible behavioural mechanism through which climate variability may affect population processes.

  5. Large scale injection test (LASGIT) modelling

    International Nuclear Information System (INIS)

    Arnedo, D.; Olivella, S.; Alonso, E.E.

    2010-01-01

    Document available in extended abstract form only. With the objective of understanding the gas flow processes through clay barriers in schemes of radioactive waste disposal, the Lasgit in situ experiment was planned and is currently in progress. The modelling of the experiment will permit to better understand of the responses, to confirm hypothesis of mechanisms and processes and to learn in order to design future experiments. The experiment and modelling activities are included in the project FORGE (FP7). The in situ large scale injection test Lasgit is currently being performed at the Aespoe Hard Rock Laboratory by SKB and BGS. An schematic layout of the test is shown. The deposition hole follows the KBS3 scheme. A copper canister is installed in the axe of the deposition hole, surrounded by blocks of highly compacted MX-80 bentonite. A concrete plug is placed at the top of the buffer. A metallic lid anchored to the surrounding host rock is included in order to prevent vertical movements of the whole system during gas injection stages (high gas injection pressures are expected to be reached). Hydration of the buffer material is achieved by injecting water through filter mats, two placed at the rock walls and two at the interfaces between bentonite blocks. Water is also injected through the 12 canister filters. Gas injection stages are performed injecting gas to some of the canister injection filters. Since the water pressure and the stresses (swelling pressure development) will be high during gas injection, it is necessary to inject at high gas pressures. This implies mechanical couplings as gas penetrates after the gas entry pressure is achieved and may produce deformations which in turn lead to permeability increments. A 3D hydro-mechanical numerical model of the test using CODE-BRIGHT is presented. The domain considered for the modelling is shown. The materials considered in the simulation are the MX-80 bentonite blocks (cylinders and rings), the concrete plug

  6. Large-scale fuel cycle centers

    International Nuclear Information System (INIS)

    Smiley, S.H.; Black, K.M.

    1977-01-01

    The United States Nuclear Regulatory Commission (NRC) has considered the nuclear energy center concept for fuel cycle plants in the Nuclear Energy Center Site Survey - 1975 (NECSS-75) -- an important study mandated by the U.S. Congress in the Energy Reorganization Act of 1974 which created the NRC. For the study, NRC defined fuel cycle centers to consist of fuel reprocessing and mixed oxide fuel fabrication plants, and optional high-level waste and transuranic waste management facilities. A range of fuel cycle center sizes corresponded to the fuel throughput of power plants with a total capacity of 50,000 - 300,000 MWe. The types of fuel cycle facilities located at the fuel cycle center permit the assessment of the role of fuel cycle centers in enhancing safeguarding of strategic special nuclear materials -- plutonium and mixed oxides. Siting of fuel cycle centers presents a considerably smaller problem than the siting of reactors. A single reprocessing plant of the scale projected for use in the United States (1500-2000 MT/yr) can reprocess the fuel from reactors producing 50,000-65,000 MWe. Only two or three fuel cycle centers of the upper limit size considered in the NECSS-75 would be required in the United States by the year 2000 . The NECSS-75 fuel cycle center evaluations showed that large scale fuel cycle centers present no real technical difficulties in siting from a radiological effluent and safety standpoint. Some construction economies may be attainable with fuel cycle centers; such centers offer opportunities for improved waste management systems. Combined centers consisting of reactors and fuel reprocessing and mixed oxide fuel fabrication plants were also studied in the NECSS. Such centers can eliminate not only shipment of plutonium, but also mixed oxide fuel. Increased fuel cycle costs result from implementation of combined centers unless the fuel reprocessing plants are commercial-sized. Development of plutonium-burning reactors could reduce any

  7. Large-scale assembly of colloidal particles

    Science.gov (United States)

    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

  8. Impact of spectral nudging on the downscaling of tropical cyclones in regional climate simulations

    Science.gov (United States)

    Choi, Suk-Jin; Lee, Dong-Kyou

    2016-06-01

    This study investigated the simulations of three months of seasonal tropical cyclone (TC) activity over the western North Pacific using the Advanced Research WRF Model. In the control experiment (CTL), the TC frequency was considerably overestimated. Additionally, the tracks of some TCs tended to have larger radii of curvature and were shifted eastward. The large-scale environments of westerly monsoon flows and subtropical Pacific highs were unreasonably simulated. The overestimated frequency of TC formation was attributed to a strengthened westerly wind field in the southern quadrants of the TC center. In comparison with the experiment with the spectral nudging method, the strengthened wind speed was mainly modulated by large-scale flow that was greater than approximately 1000 km in the model domain. The spurious formation and undesirable tracks of TCs in the CTL were considerably improved by reproducing realistic large-scale atmospheric monsoon circulation with substantial adjustment between large-scale flow in the model domain and large-scale boundary forcing modified by the spectral nudging method. The realistic monsoon circulation took a vital role in simulating realistic TCs. It revealed that, in the downscaling from large-scale fields for regional climate simulations, scale interaction between model-generated regional features and forced large-scale fields should be considered, and spectral nudging is a desirable method in the downscaling method.

  9. How large-scale subsidence affects stratocumulus transitions

    Directory of Open Access Journals (Sweden)

    J. J. van der Dussen

    2016-01-01

    Full Text Available Some climate modeling results suggest that the Hadley circulation might weaken in a future climate, causing a subsequent reduction in the large-scale subsidence velocity in the subtropics. In this study we analyze the cloud liquid water path (LWP budget from large-eddy simulation (LES results of three idealized stratocumulus transition cases, each with a different subsidence rate. As shown in previous studies a reduced subsidence is found to lead to a deeper stratocumulus-topped boundary layer, an enhanced cloud-top entrainment rate and a delay in the transition of stratocumulus clouds into shallow cumulus clouds during its equatorwards advection by the prevailing trade winds. The effect of a reduction of the subsidence rate can be summarized as follows. The initial deepening of the stratocumulus layer is partly counteracted by an enhanced absorption of solar radiation. After some hours the deepening of the boundary layer is accelerated by an enhancement of the entrainment rate. Because this is accompanied by a change in the cloud-base turbulent fluxes of moisture and heat, the net change in the LWP due to changes in the turbulent flux profiles is negligibly small.

  10. FFTLasso: Large-Scale LASSO in the Fourier Domain

    KAUST Repository

    Bibi, Adel Aamer

    2017-11-09

    In this paper, we revisit the LASSO sparse representation problem, which has been studied and used in a variety of different areas, ranging from signal processing and information theory to computer vision and machine learning. In the vision community, it found its way into many important applications, including face recognition, tracking, super resolution, image denoising, to name a few. Despite advances in efficient sparse algorithms, solving large-scale LASSO problems remains a challenge. To circumvent this difficulty, people tend to downsample and subsample the problem (e.g. via dimensionality reduction) to maintain a manageable sized LASSO, which usually comes at the cost of losing solution accuracy. This paper proposes a novel circulant reformulation of the LASSO that lifts the problem to a higher dimension, where ADMM can be efficiently applied to its dual form. Because of this lifting, all optimization variables are updated using only basic element-wise operations, the most computationally expensive of which is a 1D FFT. In this way, there is no need for a linear system solver nor matrix-vector multiplication. Since all operations in our FFTLasso method are element-wise, the subproblems are completely independent and can be trivially parallelized (e.g. on a GPU). The attractive computational properties of FFTLasso are verified by extensive experiments on synthetic and real data and on the face recognition task. They demonstrate that FFTLasso scales much more effectively than a state-of-the-art solver.

  11. FFTLasso: Large-Scale LASSO in the Fourier Domain

    KAUST Repository

    Bibi, Adel Aamer; Itani, Hani; Ghanem, Bernard

    2017-01-01

    In this paper, we revisit the LASSO sparse representation problem, which has been studied and used in a variety of different areas, ranging from signal processing and information theory to computer vision and machine learning. In the vision community, it found its way into many important applications, including face recognition, tracking, super resolution, image denoising, to name a few. Despite advances in efficient sparse algorithms, solving large-scale LASSO problems remains a challenge. To circumvent this difficulty, people tend to downsample and subsample the problem (e.g. via dimensionality reduction) to maintain a manageable sized LASSO, which usually comes at the cost of losing solution accuracy. This paper proposes a novel circulant reformulation of the LASSO that lifts the problem to a higher dimension, where ADMM can be efficiently applied to its dual form. Because of this lifting, all optimization variables are updated using only basic element-wise operations, the most computationally expensive of which is a 1D FFT. In this way, there is no need for a linear system solver nor matrix-vector multiplication. Since all operations in our FFTLasso method are element-wise, the subproblems are completely independent and can be trivially parallelized (e.g. on a GPU). The attractive computational properties of FFTLasso are verified by extensive experiments on synthetic and real data and on the face recognition task. They demonstrate that FFTLasso scales much more effectively than a state-of-the-art solver.

  12. Thermal power generation projects ``Large Scale Solar Heating``; EU-Thermie-Projekte ``Large Scale Solar Heating``

    Energy Technology Data Exchange (ETDEWEB)

    Kuebler, R.; Fisch, M.N. [Steinbeis-Transferzentrum Energie-, Gebaeude- und Solartechnik, Stuttgart (Germany)

    1998-12-31

    The aim of this project is the preparation of the ``Large-Scale Solar Heating`` programme for an Europe-wide development of subject technology. The following demonstration programme was judged well by the experts but was not immediately (1996) accepted for financial subsidies. In November 1997 the EU-commission provided 1,5 million ECU which allowed the realisation of an updated project proposal. By mid 1997 a small project was approved, that had been requested under the lead of Chalmes Industriteteknik (CIT) in Sweden and is mainly carried out for the transfer of technology. (orig.) [Deutsch] Ziel dieses Vorhabens ist die Vorbereitung eines Schwerpunktprogramms `Large Scale Solar Heating`, mit dem die Technologie europaweit weiterentwickelt werden sollte. Das daraus entwickelte Demonstrationsprogramm wurde von den Gutachtern positiv bewertet, konnte jedoch nicht auf Anhieb (1996) in die Foerderung aufgenommen werden. Im November 1997 wurden von der EU-Kommission dann kurzfristig noch 1,5 Mio ECU an Foerderung bewilligt, mit denen ein aktualisierter Projektvorschlag realisiert werden kann. Bereits Mitte 1997 wurde ein kleineres Vorhaben bewilligt, das unter Federfuehrung von Chalmers Industriteknik (CIT) in Schweden beantragt worden war und das vor allem dem Technologietransfer dient. (orig.)

  13. Analysis using large-scale ringing data

    Directory of Open Access Journals (Sweden)

    Baillie, S. R.

    2004-06-01

    survival and recruitment estimates from the French CES scheme to assess the relative contributions of survival and recruitment to overall population changes. He develops a novel approach to modelling survival rates from such multi–site data by using within–year recaptures to provide a covariate of between–year recapture rates. This provided parsimonious models of variation in recapture probabilities between sites and years. The approach provides promising results for the four species investigated and can potentially be extended to similar data from other CES/MAPS schemes. The final paper by Blandine Doligez, David Thomson and Arie van Noordwijk (Doligez et al., 2004 illustrates how large-scale studies of population dynamics can be important for evaluating the effects of conservation measures. Their study is concerned with the reintroduction of White Stork populations to the Netherlands where a re–introduction programme started in 1969 had resulted in a breeding population of 396 pairs by 2000. They demonstrate the need to consider a wide range of models in order to account for potential age, time, cohort and “trap–happiness” effects. As the data are based on resightings such trap–happiness must reflect some form of heterogeneity in resighting probabilities. Perhaps surprisingly, the provision of supplementary food did not influence survival, but it may havehad an indirect effect via the alteration of migratory behaviour. Spatially explicit modelling of data gathered at many sites inevitably results in starting models with very large numbers of parameters. The problem is often complicated further by having relatively sparse data at each site, even where the total amount of data gathered is very large. Both Julliard (2004 and Doligez et al. (2004 give explicit examples of problems caused by needing to handle very large numbers of parameters and show how they overcame them for their particular data sets. Such problems involve both the choice of appropriate

  14. Automatic management software for large-scale cluster system

    International Nuclear Information System (INIS)

    Weng Yunjian; Chinese Academy of Sciences, Beijing; Sun Gongxing

    2007-01-01

    At present, the large-scale cluster system faces to the difficult management. For example the manager has large work load. It needs to cost much time on the management and the maintenance of large-scale cluster system. The nodes in large-scale cluster system are very easy to be chaotic. Thousands of nodes are put in big rooms so that some managers are very easy to make the confusion with machines. How do effectively carry on accurate management under the large-scale cluster system? The article introduces ELFms in the large-scale cluster system. Furthermore, it is proposed to realize the large-scale cluster system automatic management. (authors)

  15. North Atlantic explosive cyclones and large scale atmospheric variability modes

    Science.gov (United States)

    Liberato, Margarida L. R.

    2015-04-01

    Extreme windstorms are one of the major natural catastrophes in the extratropics, one of the most costly natural hazards in Europe and are responsible for substantial economic damages and even fatalities. During the last decades Europe witnessed major damage from winter storms such as Lothar (December 1999), Kyrill (January 2007), Klaus (January 2009), Xynthia (February 2010), Gong (January 2013) and Stephanie (February 2014) which exhibited uncommon characteristics. In fact, most of these storms crossed the Atlantic in direction of Europe experiencing an explosive development at unusual lower latitudes along the edge of the dominant North Atlantic storm track and reaching Iberia with an uncommon intensity (Liberato et al., 2011; 2013; Liberato 2014). Results show that the explosive cyclogenesis process of most of these storms at such low latitudes is driven by: (i) the southerly displacement of a very strong polar jet stream; and (ii) the presence of an atmospheric river (AR), that is, by a (sub)tropical moisture export over the western and central (sub)tropical Atlantic which converges into the cyclogenesis region and then moves along with the storm towards Iberia. Previous studies have pointed to a link between the North Atlantic Oscillation (NAO) and intense European windstorms. On the other hand, the NAO exerts a decisive control on the average latitudinal location of the jet stream over the North Atlantic basin (Woollings et al. 2010). In this work the link between North Atlantic explosive cyclogenesis, atmospheric rivers and large scale atmospheric variability modes is reviewed and discussed. Liberato MLR (2014) The 19 January 2013 windstorm over the north Atlantic: Large-scale dynamics and impacts on Iberia. Weather and Climate Extremes, 5-6, 16-28. doi: 10.1016/j.wace.2014.06.002 Liberato MRL, Pinto JG, Trigo IF, Trigo RM. (2011) Klaus - an exceptional winter storm over Northern Iberia and Southern France. Weather 66:330-334. doi:10.1002/wea.755 Liberato

  16. Large scale chromatographic separations using continuous displacement chromatography (CDC)

    International Nuclear Information System (INIS)

    Taniguchi, V.T.; Doty, A.W.; Byers, C.H.

    1988-01-01

    A process for large scale chromatographic separations using a continuous chromatography technique is described. The process combines the advantages of large scale batch fixed column displacement chromatography with conventional analytical or elution continuous annular chromatography (CAC) to enable large scale displacement chromatography to be performed on a continuous basis (CDC). Such large scale, continuous displacement chromatography separations have not been reported in the literature. The process is demonstrated with the ion exchange separation of a binary lanthanide (Nd/Pr) mixture. The process is, however, applicable to any displacement chromatography separation that can be performed using conventional batch, fixed column chromatography

  17. Large scale features and energetics of the hybrid subtropical low `Duck' over the Tasman Sea

    Science.gov (United States)

    Pezza, Alexandre Bernardes; Garde, Luke Andrew; Veiga, José Augusto Paixão; Simmonds, Ian

    2014-01-01

    New aspects of the genesis and partial tropical transition of a rare hybrid subtropical cyclone on the eastern Australian coast are presented. The `Duck' (March 2001) attracted more recent attention due to its underlying genesis mechanisms being remarkably similar to the first South Atlantic hurricane (March 2004). Here we put this cyclone in climate perspective, showing that it belongs to a class within the 1 % lowest frequency percentile in the Southern Hemisphere as a function of its thermal evolution. A large scale analysis reveals a combined influence from an existing tropical cyclone and a persistent mid-latitude block. A Lagrangian tracer showed that the upper level air parcels arriving at the cyclone's center had been modified by the blocking. Lorenz energetics is used to identify connections with both tropical and extratropical processes, and reveal how these create the large scale environment conducive to the development of the vortex. The results reveal that the blocking exerted the most important influence, with a strong peak in barotropic generation of kinetic energy over a large area traversed by the air parcels just before genesis. A secondary peak also coincided with the first time the cyclone developed an upper level warm core, but with insufficient amplitude to allow for a full tropical transition. The applications of this technique are numerous and promising, particularly on the use of global climate models to infer changes in environmental parameters associated with severe storms.

  18. Influences of large-scale convection and moisture source on monthly precipitation isotope ratios observed in Thailand, Southeast Asia

    Science.gov (United States)

    Wei, Zhongwang; Lee, Xuhui; Liu, Zhongfang; Seeboonruang, Uma; Koike, Masahiro; Yoshimura, Kei

    2018-04-01

    Many paleoclimatic records in Southeast Asia rely on rainfall isotope ratios as proxies for past hydroclimatic variability. However, the physical processes controlling modern rainfall isotopic behaviors in the region is poorly constrained. Here, we combined isotopic measurements at six sites across Thailand with an isotope-incorporated atmospheric circulation model (IsoGSM) and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to investigate the factors that govern the variability of precipitation isotope ratios in this region. Results show that rainfall isotope ratios are both correlated with local rainfall amount and regional outgoing longwave radiation, suggesting that rainfall isotope ratios in this region are controlled not only by local rain amount (amount effect) but also by large-scale convection. As a transition zone between the Indian monsoon and the western North Pacific monsoon, the spatial difference of observed precipitation isotope among different sites are associated with moisture source. These results highlight the importance of regional processes in determining rainfall isotope ratios in the tropics and provide constraints on the interpretation of paleo-precipitation isotope records in the context of regional climate dynamics.

  19. Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

    Energy Technology Data Exchange (ETDEWEB)

    Gray, W.M.; Sheaffer, J.D.; Thorson, W.B. [Colorado State Univ., Fort Collins, CO (United States)

    1996-04-01

    Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

  20. Prospects for large scale electricity storage in Denmark

    DEFF Research Database (Denmark)

    Krog Ekman, Claus; Jensen, Søren Højgaard

    2010-01-01

    In a future power systems with additional wind power capacity there will be an increased need for large scale power management as well as reliable balancing and reserve capabilities. Different technologies for large scale electricity storage provide solutions to the different challenges arising w...

  1. Large-scale matrix-handling subroutines 'ATLAS'

    International Nuclear Information System (INIS)

    Tsunematsu, Toshihide; Takeda, Tatsuoki; Fujita, Keiichi; Matsuura, Toshihiko; Tahara, Nobuo

    1978-03-01

    Subroutine package ''ATLAS'' has been developed for handling large-scale matrices. The package is composed of four kinds of subroutines, i.e., basic arithmetic routines, routines for solving linear simultaneous equations and for solving general eigenvalue problems and utility routines. The subroutines are useful in large scale plasma-fluid simulations. (auth.)

  2. Large-scale Agricultural Land Acquisitions in West Africa | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project will examine large-scale agricultural land acquisitions in nine West African countries -Burkina Faso, Guinea-Bissau, Guinea, Benin, Mali, Togo, Senegal, Niger, and Côte d'Ivoire. ... They will use the results to increase public awareness and knowledge about the consequences of large-scale land acquisitions.

  3. Large-scale synthesis of YSZ nanopowder by Pechini method

    Indian Academy of Sciences (India)

    Administrator

    structure and chemical purity of 99⋅1% by inductively coupled plasma optical emission spectroscopy on a large scale. Keywords. Sol–gel; yttria-stabilized zirconia; large scale; nanopowder; Pechini method. 1. Introduction. Zirconia has attracted the attention of many scientists because of its tremendous thermal, mechanical ...

  4. GAS MIXING ANALYSIS IN A LARGE-SCALED SALTSTONE FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S

    2008-05-28

    Computational fluid dynamics (CFD) methods have been used to estimate the flow patterns mainly driven by temperature gradients inside vapor space in a large-scaled Saltstone vault facility at Savannah River site (SRS). The purpose of this work is to examine the gas motions inside the vapor space under the current vault configurations by taking a three-dimensional transient momentum-energy coupled approach for the vapor space domain of the vault. The modeling calculations were based on prototypic vault geometry and expected normal operating conditions as defined by Waste Solidification Engineering. The modeling analysis was focused on the air flow patterns near the ventilated corner zones of the vapor space inside the Saltstone vault. The turbulence behavior and natural convection mechanism used in the present model were benchmarked against the literature information and theoretical results. The verified model was applied to the Saltstone vault geometry for the transient assessment of the air flow patterns inside the vapor space of the vault region using the potential operating conditions. The baseline model considered two cases for the estimations of the flow patterns within the vapor space. One is the reference nominal case. The other is for the negative temperature gradient between the roof inner and top grout surface temperatures intended for the potential bounding condition. The flow patterns of the vapor space calculated by the CFD model demonstrate that the ambient air comes into the vapor space of the vault through the lower-end ventilation hole, and it gets heated up by the Benard-cell type circulation before leaving the vault via the higher-end ventilation hole. The calculated results are consistent with the literature information. Detailed results and the cases considered in the calculations will be discussed here.

  5. ENSO dynamics and seasonal cycle in the tropical Pacific as simulated by the ECHAM4/OPYC3 coupled general circulation model

    Energy Technology Data Exchange (ETDEWEB)

    Bacher, A. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Oberhuber, J.M. [Deutsches Klimarechenzentrum (DKRZ), Hamburg (Germany); Roeckner, E. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)

    1996-07-01

    The new version of the atmospheric general circulation model, ECHAM4, at the Max Planck Institute for Meteorology, Hamburg, has been coupled to the OPYC3 isopycnic global ocean general circulation and sea ice model (Oberhuber 1993) in a multi-century present-day climate simulation. Nonseasonal constant flux adjustment for heat and freshwater was employed to ensure a long-term annual mean state close to present day climatology. This paper examines the simulated upper ocean seasonal cycle and interannual variability in the tropical Pacific for the first 100 years. The coupled model`s seasonal cycle of tropical Pacific SSTs is in good agreement with the observations with respect to both the warm pool variation and the Central and Eastern Pacific, with significant errors (up to -2 K) only in the cold tongue around April. The cold phase cold tongue extent and strength is as observed, and for this the heat flux adjustment does not play the decisive role; corrections beyond {+-}40 Wm{sup -2} are rare and only occupy small areas, such as near coasts. A well established south Pacific convergence zone is characteristic for the new AGCM version. Apart from extending the south-east trades seasonal maximum to midbasin, windstress pattern and strength are well captured. The subsurface structure is overall consistent with the observed, with a realistically sharp thermocline at about 150 m depth in the west and rising to the surface from 160 W to 100 W.

  6. Algorithm 896: LSA: Algorithms for Large-Scale Optimization

    Czech Academy of Sciences Publication Activity Database

    Lukšan, Ladislav; Matonoha, Ctirad; Vlček, Jan

    2009-01-01

    Roč. 36, č. 3 (2009), 16-1-16-29 ISSN 0098-3500 R&D Pro jects: GA AV ČR IAA1030405; GA ČR GP201/06/P397 Institutional research plan: CEZ:AV0Z10300504 Keywords : algorithms * design * large-scale optimization * large-scale nonsmooth optimization * large-scale nonlinear least squares * large-scale nonlinear minimax * large-scale systems of nonlinear equations * sparse pro blems * partially separable pro blems * limited-memory methods * discrete Newton methods * quasi-Newton methods * primal interior-point methods Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.904, year: 2009

  7. Applications of Data Assimilation to Analysis of the Ocean on Large Scales

    Science.gov (United States)

    Miller, Robert N.; Busalacchi, Antonio J.; Hackert, Eric C.

    1997-01-01

    It is commonplace to begin talks on this topic by noting that oceanographic data are too scarce and sparse to provide complete initial and boundary conditions for large-scale ocean models. Even considering the availability of remotely-sensed data such as radar altimetry from the TOPEX and ERS-1 satellites, a glance at a map of available subsurface data should convince most observers that this is still the case. Data are still too sparse for comprehensive treatment of interannual to interdecadal climate change through the use of models, since the new data sets have not been around for very long. In view of the dearth of data, we must note that the overall picture is changing rapidly. Recently, there have been a number of large scale ocean analysis and prediction efforts, some of which now run on an operational or at least quasi-operational basis, most notably the model based analyses of the tropical oceans. These programs are modeled on numerical weather prediction. Aside from the success of the global tide models, assimilation of data in the tropics, in support of prediction and analysis of seasonal to interannual climate change, is probably the area of large scale ocean modeling and data assimilation in which the most progress has been made. Climate change is a problem which is particularly suited to advanced data assimilation methods. Linear models are useful, and the linear theory can be exploited. For the most part, the data are sufficiently sparse that implementation of advanced methods is worthwhile. As an example of a large scale data assimilation experiment with a recent extensive data set, we present results of a tropical ocean experiment in which the Kalman filter was used to assimilate three years of altimetric data from Geosat into a coarsely resolved linearized long wave shallow water model. Since nonlinear processes dominate the local dynamic signal outside the tropics, subsurface dynamical quantities cannot be reliably inferred from surface height

  8. Probabilistic discrimination between large-scale environments of intensifying and decaying African Easterly Waves

    Energy Technology Data Exchange (ETDEWEB)

    Agudelo, Paula A. [Area Hidrometria e Instrumentacion Carrera, Empresas Publicas de Medellin, Medellin (Colombia); Hoyos, Carlos D.; Curry, Judith A.; Webster, Peter J. [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA (United States)

    2011-04-15

    About 50-60% of Atlantic tropical cyclones (TCs) including nearly 85% of intense hurricanes have their origins as African Easterly Waves (AEWs). However, predicting the likelihood of AEW intensification remains a difficult task. We have developed a Bayesian diagnostic methodology to understand genesis of North Atlantic TCs spawned by AEWs through the examination of the characteristics of the AEW itself together with the large-scale environment, resulting in a probabilistic discrimination between large-scale environments associated with intensifying and decaying AEWs. The methodology is based on a new objective and automatic AEW tracking scheme used for the period 1980 to 2001 based on spatio-temporally Fourier-filtered relative vorticity and meridional winds at different levels and outgoing long wave radiation. Using the AEW and Hurricane Best Track Files (HURDAT) data sets, probability density functions of environmental variables that discriminate between AEWs that decay, become TCs or become major hurricanes are determined. Results indicate that the initial amplitude of the AEWs is a major determinant for TC genesis, and that TC genesis risk increases when the wave enters an environment characterized by pre-existing large-scale convergence and moist convection. For the prediction of genesis, the most useful variables are column integrated heating, vertical velocity and specific humidity, and a combined form of divergence and vertical velocity and SST. It is also found that the state of the large-scale environment modulates the annual cycle and interannual variability of the AEW intensification efficiency. (orig.)

  9. Large Scale Meteorological Pattern of Extreme Rainfall in Indonesia

    Science.gov (United States)

    Kuswanto, Heri; Grotjahn, Richard; Rachmi, Arinda; Suhermi, Novri; Oktania, Erma; Wijaya, Yosep

    2014-05-01

    Extreme Weather Events (EWEs) cause negative impacts socially, economically, and environmentally. Considering these facts, forecasting EWEs is crucial work. Indonesia has been identified as being among the countries most vulnerable to the risk of natural disasters, such as floods, heat waves, and droughts. Current forecasting of extreme events in Indonesia is carried out by interpreting synoptic maps for several fields without taking into account the link between the observed events in the 'target' area with remote conditions. This situation may cause misidentification of the event leading to an inaccurate prediction. Grotjahn and Faure (2008) compute composite maps from extreme events (including heat waves and intense rainfall) to help forecasters identify such events in model output. The composite maps show large scale meteorological patterns (LSMP) that occurred during historical EWEs. Some vital information about the EWEs can be acquired from studying such maps, in addition to providing forecaster guidance. Such maps have robust mid-latitude meteorological patterns (for Sacramento and California Central Valley, USA EWEs). We study the performance of the composite approach for tropical weather condition such as Indonesia. Initially, the composite maps are developed to identify and forecast the extreme weather events in Indramayu district- West Java, the main producer of rice in Indonesia and contributes to about 60% of the national total rice production. Studying extreme weather events happening in Indramayu is important since EWEs there affect national agricultural and fisheries activities. During a recent EWE more than a thousand houses in Indramayu suffered from serious flooding with each home more than one meter underwater. The flood also destroyed a thousand hectares of rice plantings in 5 regencies. Identifying the dates of extreme events is one of the most important steps and has to be carried out carefully. An approach has been applied to identify the

  10. RELATIONSHIPS BETWEEN ZONAL WIND ANOMALIES IN HIGH AND LOW TROPOSPHERE AND ANNUAL FREQUENCY OF NW PACIFIC TROPICAL CYCLONES

    Institute of Scientific and Technical Information of China (English)

    GONG Zhen-song; HE Min

    2007-01-01

    Relationships between large-scale zonal wind anomalies and annual frequency of NW Pacific tropical cyclones and possible mechanisms are investigated with the methods of correlation and composition.It is indicated that when △ U200-△U850 >0 in the eastern tropical Pacific and △ U200- △U850 <0 in western tropical Pacific, the Walker cell is stronger in the Pacific tropical region and the annual frequency of NW Pacific tropical cyclone are above normal. In the years with zonal wind anomalies, the circulation of high and low troposphere and the vertical motions in the troposphere have significant characteristics. In the time scale of short-range climate prediction, zonal wind anomalies in high and low troposphere are useful as a preliminary signal of the annual frequency prediction of NW Pacific tropical cyclones.

  11. An Novel Architecture of Large-scale Communication in IOT

    Science.gov (United States)

    Ma, Wubin; Deng, Su; Huang, Hongbin

    2018-03-01

    In recent years, many scholars have done a great deal of research on the development of Internet of Things and networked physical systems. However, few people have made the detailed visualization of the large-scale communications architecture in the IOT. In fact, the non-uniform technology between IPv6 and access points has led to a lack of broad principles of large-scale communications architectures. Therefore, this paper presents the Uni-IPv6 Access and Information Exchange Method (UAIEM), a new architecture and algorithm that addresses large-scale communications in the IOT.

  12. Large scale and big data processing and management

    CERN Document Server

    Sakr, Sherif

    2014-01-01

    Large Scale and Big Data: Processing and Management provides readers with a central source of reference on the data management techniques currently available for large-scale data processing. Presenting chapters written by leading researchers, academics, and practitioners, it addresses the fundamental challenges associated with Big Data processing tools and techniques across a range of computing environments.The book begins by discussing the basic concepts and tools of large-scale Big Data processing and cloud computing. It also provides an overview of different programming models and cloud-bas

  13. Comparison Between Overtopping Discharge in Small and Large Scale Models

    DEFF Research Database (Denmark)

    Helgason, Einar; Burcharth, Hans F.

    2006-01-01

    The present paper presents overtopping measurements from small scale model test performed at the Haudraulic & Coastal Engineering Laboratory, Aalborg University, Denmark and large scale model tests performed at the Largde Wave Channel,Hannover, Germany. Comparison between results obtained from...... small and large scale model tests show no clear evidence of scale effects for overtopping above a threshold value. In the large scale model no overtopping was measured for waveheights below Hs = 0.5m as the water sunk into the voids between the stones on the crest. For low overtopping scale effects...

  14. Computation of large scale currents in the Arabian Sea during winter using a semi-diagnostic model

    Digital Repository Service at National Institute of Oceanography (India)

    Shaji, C.; Bahulayan, N.; Rao, A.D.; Dube, S.K.

    A 3-dimensional, semi-diagnostic model with 331 levels in the vertical has been used for the computation of climatic circulation in the western tropical Indian Ocean. Model is driven with the seasonal mean data on wind stress, temperature...

  15. The Influence of Volcanic Eruptions on the Climate of Tropical South America During the Last Millennium in an Isotope-Enabled General Circulation Model

    Science.gov (United States)

    Colose, Christopher M.; LeGrande, Allegra N.; Vuille, Mathias

    2016-01-01

    Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El Niño-Southern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850 CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium. An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records. Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the "amount effect". During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is

  16. Supplement of: The Influence of Volcanic Eruptions on the Climate of Tropical South America During the Last Millennium in an Isotope-Enabled General Circulation Model

    Science.gov (United States)

    Colose, Christopher; LeGrande, Allegra N.; Vuille, Mathias

    2016-01-01

    Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El NioSouthern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium.An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records.Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the amount effect. During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is larger

  17. Large-scale control of mosquito vectors of disease

    International Nuclear Information System (INIS)

    Curtis, C.F.; Andreasen, M.H.

    2000-01-01

    By far the most important vector borne disease is malaria transmitted by Anopheles mosquitoes causing an estimated 300-500 million clinical cases per year and 1.4-2.6 million deaths, mostly in tropical Africa (WHO 1995). The second most important mosquito borne disease is lymphatic filariasis, but there are now such effective, convenient and cheap drugs for its treatment that vector control will now have at most a supplementary role (Maxwell et al. 1999a). The only other mosquito borne disease likely to justify large-scale vector control is dengue which is carried in urban areas of Southeast Asia and Latin America by Aedes aegypti L. which was also the urban vector of yellow fever in Latin America. This mosquito was eradicated from most countries of Latin America between the 1930s and 60s but, unfortunately in recent years, it has been allowed to re-infest and cause serious dengue epidemics, except in Cuba where it has been held close to eradication (Reiter and Gubler 1997). In the 1930s and 40s, invasions by An. gambiae Giles s.l., the main tropical African malaria vector, were eradicated from Brazil (Soper and Wilson 1943) and Egypt (Shousha 1947). It is surprising that greatly increased air traffic has not led to more such invasions of apparently climatically suitable areas, e.g., of Polynesia which has no anophelines and therefore no malaria. The above mentioned temporary or permanent eradications were achieved before the advent of DDT, using larvicidal methods (of a kind which would now be considered environmentally unacceptable) carried out by rigorously disciplined teams. MALARIA Between the end of the Second World War and the 1960s, the availability of DDT for spraying of houses allowed eradication of malaria from the Soviet Union, southern Europe, the USA, northern Venezuela and Guyana, Taiwan and the Caribbean Islands, apart from Hispaniola. Its range and intensity were also greatly reduced in China, India and South Africa and, at least temporarily, in

  18. Large-scale land transformations in Indonesia: The role of ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... enable timely responses to the impacts of large-scale land transformations in Central Kalimantan ... In partnership with UNESCO's Organization for Women in Science for the ... New funding opportunity for gender equality and climate change.

  19. Resolute large scale mining company contribution to health services of

    African Journals Online (AJOL)

    Resolute large scale mining company contribution to health services of Lusu ... in terms of socio economic, health, education, employment, safe drinking water, ... The data were analyzed using Scientific Package for Social Science (SPSS).

  20. Personalized Opportunistic Computing for CMS at Large Scale

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    **Douglas Thain** is an Associate Professor of Computer Science and Engineering at the University of Notre Dame, where he designs large scale distributed computing systems to power the needs of advanced science and...

  1. Bottom-Up Accountability Initiatives and Large-Scale Land ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Corey Piccioni

    fuel/energy, climate, and finance has occurred and one of the most ... this wave of large-scale land acquisitions. In fact, esti- ... Environmental Rights Action/Friends of the Earth,. Nigeria ... map the differentiated impacts (gender, ethnicity,.

  2. Large-scale linear programs in planning and prediction.

    Science.gov (United States)

    2017-06-01

    Large-scale linear programs are at the core of many traffic-related optimization problems in both planning and prediction. Moreover, many of these involve significant uncertainty, and hence are modeled using either chance constraints, or robust optim...

  3. Bottom-Up Accountability Initiatives and Large-Scale Land ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... Security can help increase accountability for large-scale land acquisitions in ... to build decent economic livelihoods and participate meaningfully in decisions ... its 2017 call for proposals to establish Cyber Policy Centres in the Global South.

  4. Amplification of large-scale magnetic field in nonhelical magnetohydrodynamics

    KAUST Repository

    Kumar, Rohit

    2017-08-11

    It is typically assumed that the kinetic and magnetic helicities play a crucial role in the growth of large-scale dynamo. In this paper, we demonstrate that helicity is not essential for the amplification of large-scale magnetic field. For this purpose, we perform nonhelical magnetohydrodynamic (MHD) simulation, and show that the large-scale magnetic field can grow in nonhelical MHD when random external forcing is employed at scale 1/10 the box size. The energy fluxes and shell-to-shell transfer rates computed using the numerical data show that the large-scale magnetic energy grows due to the energy transfers from the velocity field at the forcing scales.

  5. Needs, opportunities, and options for large scale systems research

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, G.L.

    1984-10-01

    The Office of Energy Research was recently asked to perform a study of Large Scale Systems in order to facilitate the development of a true large systems theory. It was decided to ask experts in the fields of electrical engineering, chemical engineering and manufacturing/operations research for their ideas concerning large scale systems research. The author was asked to distribute a questionnaire among these experts to find out their opinions concerning recent accomplishments and future research directions in large scale systems research. He was also requested to convene a conference which included three experts in each area as panel members to discuss the general area of large scale systems research. The conference was held on March 26--27, 1984 in Pittsburgh with nine panel members, and 15 other attendees. The present report is a summary of the ideas presented and the recommendations proposed by the attendees.

  6. Large-Scale 3D Printing: The Way Forward

    Science.gov (United States)

    Jassmi, Hamad Al; Najjar, Fady Al; Ismail Mourad, Abdel-Hamid

    2018-03-01

    Research on small-scale 3D printing has rapidly evolved, where numerous industrial products have been tested and successfully applied. Nonetheless, research on large-scale 3D printing, directed to large-scale applications such as construction and automotive manufacturing, yet demands a great a great deal of efforts. Large-scale 3D printing is considered an interdisciplinary topic and requires establishing a blended knowledge base from numerous research fields including structural engineering, materials science, mechatronics, software engineering, artificial intelligence and architectural engineering. This review article summarizes key topics of relevance to new research trends on large-scale 3D printing, particularly pertaining (1) technological solutions of additive construction (i.e. the 3D printers themselves), (2) materials science challenges, and (3) new design opportunities.

  7. No Large Scale Curvature Perturbations during Waterfall of Hybrid Inflation

    OpenAIRE

    Abolhasani, Ali Akbar; Firouzjahi, Hassan

    2010-01-01

    In this paper the possibility of generating large scale curvature perturbations induced from the entropic perturbations during the waterfall phase transition of standard hybrid inflation model is studied. We show that whether or not appreciable amounts of large scale curvature perturbations are produced during the waterfall phase transition depend crucially on the competition between the classical and the quantum mechanical back-reactions to terminate inflation. If one considers only the clas...

  8. Bayesian hierarchical model for large-scale covariance matrix estimation.

    Science.gov (United States)

    Zhu, Dongxiao; Hero, Alfred O

    2007-12-01

    Many bioinformatics problems implicitly depend on estimating large-scale covariance matrix. The traditional approaches tend to give rise to high variance and low accuracy due to "overfitting." We cast the large-scale covariance matrix estimation problem into the Bayesian hierarchical model framework, and introduce dependency between covariance parameters. We demonstrate the advantages of our approaches over the traditional approaches using simulations and OMICS data analysis.

  9. Benefits of transactive memory systems in large-scale development

    OpenAIRE

    Aivars, Sablis

    2016-01-01

    Context. Large-scale software development projects are those consisting of a large number of teams, maybe even spread across multiple locations, and working on large and complex software tasks. That means that neither a team member individually nor an entire team holds all the knowledge about the software being developed and teams have to communicate and coordinate their knowledge. Therefore, teams and team members in large-scale software development projects must acquire and manage expertise...

  10. Capabilities of the Large-Scale Sediment Transport Facility

    Science.gov (United States)

    2016-04-01

    pump flow meters, sediment trap weigh tanks , and beach profiling lidar. A detailed discussion of the original LSTF features and capabilities can be...ERDC/CHL CHETN-I-88 April 2016 Approved for public release; distribution is unlimited. Capabilities of the Large-Scale Sediment Transport...describes the Large-Scale Sediment Transport Facility (LSTF) and recent upgrades to the measurement systems. The purpose of these upgrades was to increase

  11. Comparative Analysis of Different Protocols to Manage Large Scale Networks

    OpenAIRE

    Anil Rao Pimplapure; Dr Jayant Dubey; Prashant Sen

    2013-01-01

    In recent year the numbers, complexity and size is increased in Large Scale Network. The best example of Large Scale Network is Internet, and recently once are Data-centers in Cloud Environment. In this process, involvement of several management tasks such as traffic monitoring, security and performance optimization is big task for Network Administrator. This research reports study the different protocols i.e. conventional protocols like Simple Network Management Protocol and newly Gossip bas...

  12. Trends in large-scale testing of reactor structures

    International Nuclear Information System (INIS)

    Blejwas, T.E.

    2003-01-01

    Large-scale tests of reactor structures have been conducted at Sandia National Laboratories since the late 1970s. This paper describes a number of different large-scale impact tests, pressurization tests of models of containment structures, and thermal-pressure tests of models of reactor pressure vessels. The advantages of large-scale testing are evident, but cost, in particular limits its use. As computer models have grown in size, such as number of degrees of freedom, the advent of computer graphics has made possible very realistic representation of results - results that may not accurately represent reality. A necessary condition to avoiding this pitfall is the validation of the analytical methods and underlying physical representations. Ironically, the immensely larger computer models sometimes increase the need for large-scale testing, because the modeling is applied to increasing more complex structural systems and/or more complex physical phenomena. Unfortunately, the cost of large-scale tests is a disadvantage that will likely severely limit similar testing in the future. International collaborations may provide the best mechanism for funding future programs with large-scale tests. (author)

  13. A climatological analysis of high-precipitation events in Dronning Maud Land, Antarctica, and associated large-scale atmospheric conditions

    NARCIS (Netherlands)

    Welker, Christoph; Martius, Olivia; Froidevaux, Paul; Reijmer, Carleen H.; Fischer, Hubertus

    2014-01-01

    The link between high precipitation in Dronning Maud Land (DML), Antarctica, and the large-scale atmospheric circulation is investigated using ERA-Interim data for 1979-2009. High-precipitation events are analyzed at Halvfarryggen situated in the coastal region of DML and at Kohnen Station located

  14. Improving Prediction of Large-scale Regime Transitions

    Science.gov (United States)

    Gyakum, J. R.; Roebber, P.; Bosart, L. F.; Honor, A.; Bunker, E.; Low, Y.; Hart, J.; Bliankinshtein, N.; Kolly, A.; Atallah, E.; Huang, Y.

    2017-12-01

    Cool season atmospheric predictability over the CONUS on subseasonal times scales (1-4 weeks) is critically dependent upon the structure, configuration, and evolution of the North Pacific jet stream (NPJ). The NPJ can be perturbed on its tropical side on synoptic time scales by recurving and transitioning tropical cyclones (TCs) and on subseasonal time scales by longitudinally varying convection associated with the Madden-Julian Oscillation (MJO). Likewise, the NPJ can be perturbed on its poleward side on synoptic time scales by midlatitude and polar disturbances that originate over the Asian continent. These midlatitude and polar disturbances can often trigger downstream Rossby wave propagation across the North Pacific, North America, and the North Atlantic. The project team is investigating the following multiscale processes and features: the spatiotemporal distribution of cyclone clustering over the Northern Hemisphere; cyclone clustering as influenced by atmospheric blocking and the phases and amplitudes of the major teleconnection indices, ENSO and the MJO; composite and case study analyses of representative cyclone clustering events to establish the governing dynamics; regime change predictability horizons associated with cyclone clustering events; Arctic air mass generation and modification; life cycles of the MJO; and poleward heat and moisture transports of subtropical air masses. A critical component of the study is weather regime classification. These classifications are defined through: the spatiotemporal clustering of surface cyclogenesis; a general circulation metric combining data at 500-hPa and the dynamic tropopause; Self Organizing Maps (SOM), constructed from dynamic tropopause and 850 hPa equivalent potential temperature data. The resultant lattice of nodes is used to categorize synoptic classes and their predictability, as well as to determine the robustness of the CFSv2 model climate relative to observations. Transition pathways between these

  15. Phylogenetic distribution of large-scale genome patchiness

    Directory of Open Access Journals (Sweden)

    Hackenberg Michael

    2008-04-01

    Full Text Available Abstract Background The phylogenetic distribution of large-scale genome structure (i.e. mosaic compositional patchiness has been explored mainly by analytical ultracentrifugation of bulk DNA. However, with the availability of large, good-quality chromosome sequences, and the recently developed computational methods to directly analyze patchiness on the genome sequence, an evolutionary comparative analysis can be carried out at the sequence level. Results The local variations in the scaling exponent of the Detrended Fluctuation Analysis are used here to analyze large-scale genome structure and directly uncover the characteristic scales present in genome sequences. Furthermore, through shuffling experiments of selected genome regions, computationally-identified, isochore-like regions were identified as the biological source for the uncovered large-scale genome structure. The phylogenetic distribution of short- and large-scale patchiness was determined in the best-sequenced genome assemblies from eleven eukaryotic genomes: mammals (Homo sapiens, Pan troglodytes, Mus musculus, Rattus norvegicus, and Canis familiaris, birds (Gallus gallus, fishes (Danio rerio, invertebrates (Drosophila melanogaster and Caenorhabditis elegans, plants (Arabidopsis thaliana and yeasts (Saccharomyces cerevisiae. We found large-scale patchiness of genome structure, associated with in silico determined, isochore-like regions, throughout this wide phylogenetic range. Conclusion Large-scale genome structure is detected by directly analyzing DNA sequences in a wide range of eukaryotic chromosome sequences, from human to yeast. In all these genomes, large-scale patchiness can be associated with the isochore-like regions, as directly detected in silico at the sequence level.

  16. ['Piracy of kowledge'--the role of a buccaneer-scientist in the knowledge circulation around diseases and drugs in the tropics].

    Science.gov (United States)

    Snelders, Stephen

    2009-01-01

    Knowledge circulation in the seventeenth and eighteenth centuries was not only stimulated by the mutual interaction of trade and science. In the context of territorial expansion, war, and the activities of privateers and pirates, knowledge of diseases and drugs in the tropics was increased as well. An important part in this process was performed by so-called 'buccaneer-scientists': adventurers with medical and scientific backgrounds and/or interest who operated on the cultural borders in different parts of the hemisphere. The characteristics of this type of contributor to Early Modern knowledge circulation are explored and analyzed in the example of Scottish surgeon and pirate Lionel Wafer (c. 1660 - c. 1705). The buccaneer scientist had to share the passions of other scientists, resulting in accurate and detailed empirical observation; be able to judge the relevance of observations and 'facts'; be part of a context that stimulates these observations; be capable of describing of these observations; and be part of a network of dissemination of observations. His activities should have an important practical and pragmatic component stimulating trade, expansion and even piracy. And he should possess personal characteristics such as perseverance, a healthy constitution, and ruthlessness, to work and survive in a violent and traumatic environment. Wafer is typical for other 'buccaneer-scientists' of this period--not only pirates and privateers, but also physicians and natural explorers operating in other and more 'respectable' areas of the European overseas expansion.

  17. PKI security in large-scale healthcare networks.

    Science.gov (United States)

    Mantas, Georgios; Lymberopoulos, Dimitrios; Komninos, Nikos

    2012-06-01

    During the past few years a lot of PKI (Public Key Infrastructures) infrastructures have been proposed for healthcare networks in order to ensure secure communication services and exchange of data among healthcare professionals. However, there is a plethora of challenges in these healthcare PKI infrastructures. Especially, there are a lot of challenges for PKI infrastructures deployed over large-scale healthcare networks. In this paper, we propose a PKI infrastructure to ensure security in a large-scale Internet-based healthcare network connecting a wide spectrum of healthcare units geographically distributed within a wide region. Furthermore, the proposed PKI infrastructure facilitates the trust issues that arise in a large-scale healthcare network including multi-domain PKI infrastructures.

  18. Large-Scale Agriculture and Outgrower Schemes in Ethiopia

    DEFF Research Database (Denmark)

    Wendimu, Mengistu Assefa

    , the impact of large-scale agriculture and outgrower schemes on productivity, household welfare and wages in developing countries is highly contentious. Chapter 1 of this thesis provides an introduction to the study, while also reviewing the key debate in the contemporary land ‘grabbing’ and historical large...... sugarcane outgrower scheme on household income and asset stocks. Chapter 5 examines the wages and working conditions in ‘formal’ large-scale and ‘informal’ small-scale irrigated agriculture. The results in Chapter 2 show that moisture stress, the use of untested planting materials, and conflict over land...... commands a higher wage than ‘formal’ large-scale agriculture, while rather different wage determination mechanisms exist in the two sectors. Human capital characteristics (education and experience) partly explain the differences in wages within the formal sector, but play no significant role...

  19. Seismic safety in conducting large-scale blasts

    Science.gov (United States)

    Mashukov, I. V.; Chaplygin, V. V.; Domanov, V. P.; Semin, A. A.; Klimkin, M. A.

    2017-09-01

    In mining enterprises to prepare hard rocks for excavation a drilling and blasting method is used. With the approach of mining operations to settlements the negative effect of large-scale blasts increases. To assess the level of seismic impact of large-scale blasts the scientific staff of Siberian State Industrial University carried out expertise for coal mines and iron ore enterprises. Determination of the magnitude of surface seismic vibrations caused by mass explosions was performed using seismic receivers, an analog-digital converter with recording on a laptop. The registration results of surface seismic vibrations during production of more than 280 large-scale blasts at 17 mining enterprises in 22 settlements are presented. The maximum velocity values of the Earth’s surface vibrations are determined. The safety evaluation of seismic effect was carried out according to the permissible value of vibration velocity. For cases with exceedance of permissible values recommendations were developed to reduce the level of seismic impact.

  20. Balancing modern Power System with large scale of wind power

    DEFF Research Database (Denmark)

    Basit, Abdul; Altin, Müfit; Hansen, Anca Daniela

    2014-01-01

    Power system operators must ensure robust, secure and reliable power system operation even with a large scale integration of wind power. Electricity generated from the intermittent wind in large propor-tion may impact on the control of power system balance and thus deviations in the power system...... frequency in small or islanded power systems or tie line power flows in interconnected power systems. Therefore, the large scale integration of wind power into the power system strongly concerns the secure and stable grid operation. To ensure the stable power system operation, the evolving power system has...... to be analysed with improved analytical tools and techniques. This paper proposes techniques for the active power balance control in future power systems with the large scale wind power integration, where power balancing model provides the hour-ahead dispatch plan with reduced planning horizon and the real time...

  1. The role of large scale motions on passive scalar transport

    Science.gov (United States)

    Dharmarathne, Suranga; Araya, Guillermo; Tutkun, Murat; Leonardi, Stefano; Castillo, Luciano

    2014-11-01

    We study direct numerical simulation (DNS) of turbulent channel flow at Reτ = 394 to investigate effect of large scale motions on fluctuating temperature field which forms a passive scalar field. Statistical description of the large scale features of the turbulent channel flow is obtained using two-point correlations of velocity components. Two-point correlations of fluctuating temperature field is also examined in order to identify possible similarities between velocity and temperature fields. The two-point cross-correlations betwen the velocity and temperature fluctuations are further analyzed to establish connections between these two fields. In addition, we use proper orhtogonal decompotion (POD) to extract most dominant modes of the fields and discuss the coupling of large scale features of turbulence and the temperature field.

  2. Large-Scale Structure and Hyperuniformity of Amorphous Ices

    Science.gov (United States)

    Martelli, Fausto; Torquato, Salvatore; Giovambattista, Nicolas; Car, Roberto

    2017-09-01

    We investigate the large-scale structure of amorphous ices and transitions between their different forms by quantifying their large-scale density fluctuations. Specifically, we simulate the isothermal compression of low-density amorphous ice (LDA) and hexagonal ice to produce high-density amorphous ice (HDA). Both HDA and LDA are nearly hyperuniform; i.e., they are characterized by an anomalous suppression of large-scale density fluctuations. By contrast, in correspondence with the nonequilibrium phase transitions to HDA, the presence of structural heterogeneities strongly suppresses the hyperuniformity and the system becomes hyposurficial (devoid of "surface-area fluctuations"). Our investigation challenges the largely accepted "frozen-liquid" picture, which views glasses as structurally arrested liquids. Beyond implications for water, our findings enrich our understanding of pressure-induced structural transformations in glasses.

  3. Large-scale networks in engineering and life sciences

    CERN Document Server

    Findeisen, Rolf; Flockerzi, Dietrich; Reichl, Udo; Sundmacher, Kai

    2014-01-01

    This edited volume provides insights into and tools for the modeling, analysis, optimization, and control of large-scale networks in the life sciences and in engineering. Large-scale systems are often the result of networked interactions between a large number of subsystems, and their analysis and control are becoming increasingly important. The chapters of this book present the basic concepts and theoretical foundations of network theory and discuss its applications in different scientific areas such as biochemical reactions, chemical production processes, systems biology, electrical circuits, and mobile agents. The aim is to identify common concepts, to understand the underlying mathematical ideas, and to inspire discussions across the borders of the various disciplines.  The book originates from the interdisciplinary summer school “Large Scale Networks in Engineering and Life Sciences” hosted by the International Max Planck Research School Magdeburg, September 26-30, 2011, and will therefore be of int...

  4. A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-Eastern Tropical Upwelling System.

    Directory of Open Access Journals (Sweden)

    Saliou eFaye

    2015-09-01

    Full Text Available The climatological seasonal cycle of the sea surface temperature (SST in the north-eastern tropical Atlantic (7-25°N, 26-12°W is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ. The model annual mean heat budget has two regimes schematically. South of roughly 12°N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December is driven by upwelling dynamics off Senegal and Mauritania (15°-20°N, and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ~18°N. Vertical mixing in summer-autumn tends to cool (warm the surface north (south of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics.Keywords: SST, upwelling, circulation, heat budget, observations, modeling

  5. A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project

    Science.gov (United States)

    Ewers, Robert M.; Didham, Raphael K.; Fahrig, Lenore; Ferraz, Gonçalo; Hector, Andy; Holt, Robert D.; Kapos, Valerie; Reynolds, Glen; Sinun, Waidi; Snaddon, Jake L.; Turner, Edgar C.

    2011-01-01

    Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification. PMID:22006969

  6. A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project.

    Science.gov (United States)

    Ewers, Robert M; Didham, Raphael K; Fahrig, Lenore; Ferraz, Gonçalo; Hector, Andy; Holt, Robert D; Kapos, Valerie; Reynolds, Glen; Sinun, Waidi; Snaddon, Jake L; Turner, Edgar C

    2011-11-27

    Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification.

  7. Report of the LASCAR forum: Large scale reprocessing plant safeguards

    International Nuclear Information System (INIS)

    1992-01-01

    This report has been prepared to provide information on the studies which were carried out from 1988 to 1992 under the auspices of the multinational forum known as Large Scale Reprocessing Plant Safeguards (LASCAR) on safeguards for four large scale reprocessing plants operated or planned to be operated in the 1990s. The report summarizes all of the essential results of these studies. The participants in LASCAR were from France, Germany, Japan, the United Kingdom, the United States of America, the Commission of the European Communities - Euratom, and the International Atomic Energy Agency

  8. Large-scale structure observables in general relativity

    International Nuclear Information System (INIS)

    Jeong, Donghui; Schmidt, Fabian

    2015-01-01

    We review recent studies that rigorously define several key observables of the large-scale structure of the Universe in a general relativistic context. Specifically, we consider (i) redshift perturbation of cosmic clock events; (ii) distortion of cosmic rulers, including weak lensing shear and magnification; and (iii) observed number density of tracers of the large-scale structure. We provide covariant and gauge-invariant expressions of these observables. Our expressions are given for a linearly perturbed flat Friedmann–Robertson–Walker metric including scalar, vector, and tensor metric perturbations. While we restrict ourselves to linear order in perturbation theory, the approach can be straightforwardly generalized to higher order. (paper)

  9. Topology Optimization of Large Scale Stokes Flow Problems

    DEFF Research Database (Denmark)

    Aage, Niels; Poulsen, Thomas Harpsøe; Gersborg-Hansen, Allan

    2008-01-01

    This note considers topology optimization of large scale 2D and 3D Stokes flow problems using parallel computations. We solve problems with up to 1.125.000 elements in 2D and 128.000 elements in 3D on a shared memory computer consisting of Sun UltraSparc IV CPUs.......This note considers topology optimization of large scale 2D and 3D Stokes flow problems using parallel computations. We solve problems with up to 1.125.000 elements in 2D and 128.000 elements in 3D on a shared memory computer consisting of Sun UltraSparc IV CPUs....

  10. Fatigue Analysis of Large-scale Wind turbine

    Directory of Open Access Journals (Sweden)

    Zhu Yongli

    2017-01-01

    Full Text Available The paper does research on top flange fatigue damage of large-scale wind turbine generator. It establishes finite element model of top flange connection system with finite element analysis software MSC. Marc/Mentat, analyzes its fatigue strain, implements load simulation of flange fatigue working condition with Bladed software, acquires flange fatigue load spectrum with rain-flow counting method, finally, it realizes fatigue analysis of top flange with fatigue analysis software MSC. Fatigue and Palmgren-Miner linear cumulative damage theory. The analysis result indicates that its result provides new thinking for flange fatigue analysis of large-scale wind turbine generator, and possesses some practical engineering value.

  11. Generation of large-scale vortives in compressible helical turbulence

    International Nuclear Information System (INIS)

    Chkhetiani, O.G.; Gvaramadze, V.V.

    1989-01-01

    We consider generation of large-scale vortices in compressible self-gravitating turbulent medium. The closed equation describing evolution of the large-scale vortices in helical turbulence with finite correlation time is obtained. This equation has the form similar to the hydromagnetic dynamo equation, which allows us to call the vortx genertation effect the vortex dynamo. It is possible that principally the same mechanism is responsible both for amplification and maintenance of density waves and magnetic fields in gaseous disks of spiral galaxies. (author). 29 refs

  12. A case study on large-scale dynamical influence on bright band using cloud radar during the Indian summer monsoon

    Science.gov (United States)

    Jha, Ambuj K.; Kalapureddy, M. C. R.; Devisetty, Hari Krishna; Deshpande, Sachin M.; Pandithurai, G.

    2018-02-01

    The present study is a first of its kind attempt in exploring the physical features (e.g., height, width, intensity, duration) of tropical Indian bright band using a Ka-band cloud radar under the influence of large-scale cyclonic circulation and attempts to explain the abrupt changes in bright band features, viz., rise in the bright band height by 430 m and deepening of the bright band by about 300 m observed at around 14:00 UTC on Sep 14, 2016, synoptically as well as locally. The study extends the utility of cloud radar to understand how the bright band features are associated with light precipitation, ranging from 0 to 1.5 mm/h. Our analysis of the precipitation event of Sep 14-15, 2016 shows that the bright band above (below) 3.7 km, thickness less (more) than 300 m can potentially lead to light drizzle of 0-0.25 mm/h (drizzle/light rain) at the surface. It is also seen that the cloud radar may be suitable for bright band study within light drizzle limits than under higher rain conditions. Further, the study illustrates that the bright band features can be determined using the polarimetric capability of the cloud radar. It is shown that an LDR value of - 22 dB can be associated with the top height of bright band in the Ka-band observations which is useful in the extraction of the bright band top height and its width. This study is useful for understanding the bright band phenomenon and could be potentially useful in establishing the bright band-surface rain relationship through the perspective of a cloud radar, which would be helpful to enhance the cloud radar-based quantitative estimates of precipitation.

  13. Modeling the impact of large-scale energy conversion systems on global climate

    International Nuclear Information System (INIS)

    Williams, J.

    There are three energy options which could satisfy a projected energy requirement of about 30 TW and these are the solar, nuclear and (to a lesser extent) coal options. Climate models can be used to assess the impact of large scale deployment of these options. The impact of waste heat has been assessed using energy balance models and general circulation models (GCMs). Results suggest that the impacts are significant when the heat imput is very high and studies of more realistic scenarios are required. Energy balance models, radiative-convective models and a GCM have been used to study the impact of doubling the atmospheric CO 2 concentration. State-of-the-art models estimate a surface temperature increase of 1.5-3.0 0 C with large amplification near the poles, but much uncertainty remains. Very few model studies have been made of the impact of particles on global climate, more information on the characteristics of particle input are required. The impact of large-scale deployment of solar energy conversion systems has received little attention but model studies suggest that large scale changes in surface characteristics associated with such systems (surface heat balance, roughness and hydrological characteristics and ocean surface temperature) could have significant global climatic effects. (Auth.)

  14. Large-scale Lurgi plant would be uneconomic: study group

    Energy Technology Data Exchange (ETDEWEB)

    1964-03-21

    Gas Council and National Coal Board agreed that building of large scale Lurgi plant on the basis of study is not at present acceptable on economic grounds. The committee considered that new processes based on naphtha offered more economic sources of base and peak load production. Tables listing data provided in contractors' design studies and summary of contractors' process designs are included.

  15. Origin of large-scale cell structure in the universe

    International Nuclear Information System (INIS)

    Zel'dovich, Y.B.

    1982-01-01

    A qualitative explanation is offered for the characteristic global structure of the universe, wherein ''black'' regions devoid of galaxies are surrounded on all sides by closed, comparatively thin, ''bright'' layers populated by galaxies. The interpretation rests on some very general arguments regarding the growth of large-scale perturbations in a cold gas

  16. Large-Scale Systems Control Design via LMI Optimization

    Czech Academy of Sciences Publication Activity Database

    Rehák, Branislav

    2015-01-01

    Roč. 44, č. 3 (2015), s. 247-253 ISSN 1392-124X Institutional support: RVO:67985556 Keywords : Combinatorial linear matrix inequalities * large-scale system * decentralized control Subject RIV: BC - Control Systems Theory Impact factor: 0.633, year: 2015

  17. Identification of low order models for large scale processes

    NARCIS (Netherlands)

    Wattamwar, S.K.

    2010-01-01

    Many industrial chemical processes are complex, multi-phase and large scale in nature. These processes are characterized by various nonlinear physiochemical effects and fluid flows. Such processes often show coexistence of fast and slow dynamics during their time evolutions. The increasing demand

  18. Worldwide large-scale fluctuations of sardine and anchovy ...

    African Journals Online (AJOL)

    Worldwide large-scale fluctuations of sardine and anchovy populations. ... African Journal of Marine Science. Journal Home · ABOUT THIS JOURNAL · Advanced ... Fullscreen Fullscreen Off. http://dx.doi.org/10.2989/AJMS.2008.30.1.13.463.

  19. Worldwide large-scale fluctuations of sardine and anchovy ...

    African Journals Online (AJOL)

    Worldwide large-scale fluctuations of sardine and anchovy populations. ... African Journal of Marine Science. Journal Home · ABOUT THIS JOURNAL · Advanced ... http://dx.doi.org/10.2989/AJMS.2008.30.1.13.463 · AJOL African Journals ...

  20. Large-scale coastal impact induced by a catastrophic storm

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Andersen, Thorbjørn Joest; Johannessen, Peter N

    breaching. Our results demonstrate that violent, millennial-scale storms can trigger significant large-scale and long-term changes on barrier coasts, and that coastal changes assumed to take place over centuries or even millennia may occur in association with a single extreme storm event....

  1. Success Factors of Large Scale ERP Implementation in Thailand

    OpenAIRE

    Rotchanakitumnuai; Siriluck

    2010-01-01

    The objectives of the study are to examine the determinants of ERP implementation success factors of ERP implementation. The result indicates that large scale ERP implementation success consist of eight factors: project management competence, knowledge sharing, ERP system quality , understanding, user involvement, business process re-engineering, top management support, organization readiness.

  2. Planck intermediate results XLII. Large-scale Galactic magnetic fields

    DEFF Research Database (Denmark)

    Adam, R.; Ade, P. A. R.; Alves, M. I. R.

    2016-01-01

    Recent models for the large-scale Galactic magnetic fields in the literature have been largely constrained by synchrotron emission and Faraday rotation measures. We use three different but representative models to compare their predicted polarized synchrotron and dust emission with that measured ...

  3. Large Scale Simulations of the Euler Equations on GPU Clusters

    KAUST Repository

    Liebmann, Manfred; Douglas, Craig C.; Haase, Gundolf; Horvá th, Zoltá n

    2010-01-01

    The paper investigates the scalability of a parallel Euler solver, using the Vijayasundaram method, on a GPU cluster with 32 Nvidia Geforce GTX 295 boards. The aim of this research is to enable large scale fluid dynamics simulations with up to one

  4. Penalized Estimation in Large-Scale Generalized Linear Array Models

    DEFF Research Database (Denmark)

    Lund, Adam; Vincent, Martin; Hansen, Niels Richard

    2017-01-01

    Large-scale generalized linear array models (GLAMs) can be challenging to fit. Computation and storage of its tensor product design matrix can be impossible due to time and memory constraints, and previously considered design matrix free algorithms do not scale well with the dimension...

  5. A Chain Perspective on Large-scale Number Systems

    NARCIS (Netherlands)

    Grijpink, J.H.A.M.

    2012-01-01

    As large-scale number systems gain significance in social and economic life (electronic communication, remote electronic authentication), the correct functioning and the integrity of public number systems take on crucial importance. They are needed to uniquely indicate people, objects or phenomena

  6. Image-based Exploration of Large-Scale Pathline Fields

    KAUST Repository

    Nagoor, Omniah H.

    2014-01-01

    structure in which each pixel contains a list of pathlines segments. With this view-dependent method it is possible to filter, color-code and explore large-scale flow data in real-time. In addition, optimization techniques such as early-ray termination

  7. Temporal Variation of Large Scale Flows in the Solar Interior ...

    Indian Academy of Sciences (India)

    tribpo

    Temporal Variation of Large Scale Flows in the Solar Interior. 355. Figure 2. Zonal and meridional components of the time-dependent residual velocity at a few selected depths as marked above each panel, are plotted as contours of constant velocity in the longitude-latitude plane. The left panels show the zonal component, ...

  8. Facile Large-Scale Synthesis of 5- and 6-Carboxyfluoresceins

    DEFF Research Database (Denmark)

    Hammershøj, Peter; Ek, Pramod Kumar; Harris, Pernille

    2015-01-01

    A series of fluorescein dyes have been prepared from a common precursor through a very simple synthetic procedure, giving access to important precursors for fluorescent probes. The method has proven an efficient access to regioisomerically pure 5- and 6-carboxyfluoresceins on a large scale, in good...

  9. The Large-Scale Structure of Scientific Method

    Science.gov (United States)

    Kosso, Peter

    2009-01-01

    The standard textbook description of the nature of science describes the proposal, testing, and acceptance of a theoretical idea almost entirely in isolation from other theories. The resulting model of science is a kind of piecemeal empiricism that misses the important network structure of scientific knowledge. Only the large-scale description of…

  10. Newton Methods for Large Scale Problems in Machine Learning

    Science.gov (United States)

    Hansen, Samantha Leigh

    2014-01-01

    The focus of this thesis is on practical ways of designing optimization algorithms for minimizing large-scale nonlinear functions with applications in machine learning. Chapter 1 introduces the overarching ideas in the thesis. Chapters 2 and 3 are geared towards supervised machine learning applications that involve minimizing a sum of loss…

  11. Large-Scale Machine Learning for Classification and Search

    Science.gov (United States)

    Liu, Wei

    2012-01-01

    With the rapid development of the Internet, nowadays tremendous amounts of data including images and videos, up to millions or billions, can be collected for training machine learning models. Inspired by this trend, this thesis is dedicated to developing large-scale machine learning techniques for the purpose of making classification and nearest…

  12. Large scale solar district heating. Evaluation, modelling and designing - Appendices

    Energy Technology Data Exchange (ETDEWEB)

    Heller, A.

    2000-07-01

    The appendices present the following: A) Cad-drawing of the Marstal CSHP design. B) Key values - large-scale solar heating in Denmark. C) Monitoring - a system description. D) WMO-classification of pyranometers (solarimeters). E) The computer simulation model in TRNSYS. F) Selected papers from the author. (EHS)

  13. Proceedings of the meeting on large scale computer simulation research

    International Nuclear Information System (INIS)

    2004-04-01

    The meeting to summarize the collaboration activities for FY2003 on the Large Scale Computer Simulation Research was held January 15-16, 2004 at Theory and Computer Simulation Research Center, National Institute for Fusion Science. Recent simulation results, methodologies and other related topics were presented. (author)

  14. Chirping for large-scale maritime archaeological survey

    DEFF Research Database (Denmark)

    Grøn, Ole; Boldreel, Lars Ole

    2014-01-01

    Archaeological wrecks exposed on the sea floor are mapped using side-scan and multibeam techniques, whereas the detection of submerged archaeological sites, such as Stone Age settlements, and wrecks, partially or wholly embedded in sea-floor sediments, requires the application of high-resolution ...... the present state of this technology, it appears well suited to large-scale maritime archaeological mapping....

  15. Large-scale Homogenization of Bulk Materials in Mammoth Silos

    NARCIS (Netherlands)

    Schott, D.L.

    2004-01-01

    This doctoral thesis concerns the large-scale homogenization of bulk materials in mammoth silos. The objective of this research was to determine the best stacking and reclaiming method for homogenization in mammoth silos. For this purpose a simulation program was developed to estimate the

  16. Large Scale Survey Data in Career Development Research

    Science.gov (United States)

    Diemer, Matthew A.

    2008-01-01

    Large scale survey datasets have been underutilized but offer numerous advantages for career development scholars, as they contain numerous career development constructs with large and diverse samples that are followed longitudinally. Constructs such as work salience, vocational expectations, educational expectations, work satisfaction, and…

  17. Large Scale Anomalies of the Cosmic Microwave Background with Planck

    DEFF Research Database (Denmark)

    Frejsel, Anne Mette

    This thesis focuses on the large scale anomalies of the Cosmic Microwave Background (CMB) and their possible origins. The investigations consist of two main parts. The first part is on statistical tests of the CMB, and the consistency of both maps and power spectrum. We find that the Planck data...

  18. Fractals and the Large-Scale Structure in the Universe

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 4. Fractals and the Large-Scale Structure in the Universe - Is the Cosmological Principle Valid? A K Mittal T R Seshadri. General Article Volume 7 Issue 4 April 2002 pp 39-47 ...

  19. LARGE-SCALE COMMERCIAL INVESTMENTS IN LAND: SEEKING ...

    African Journals Online (AJOL)

    extent of large-scale investment in land or to assess its impact on the people in recipient countries. .... favorable lease terms, apparently based on a belief that this is necessary to .... Harm to the rights of local occupiers of land can result from a dearth. 24. ..... applies to a self-identified group based on the group's traditions.

  20. Mixing Metaphors: Building Infrastructure for Large Scale School Turnaround

    Science.gov (United States)

    Peurach, Donald J.; Neumerski, Christine M.

    2015-01-01

    The purpose of this analysis is to increase understanding of the possibilities and challenges of building educational infrastructure--the basic, foundational structures, systems, and resources--to support large-scale school turnaround. Building educational infrastructure often exceeds the capacity of schools, districts, and state education…

  1. Reconsidering Replication: New Perspectives on Large-Scale School Improvement

    Science.gov (United States)

    Peurach, Donald J.; Glazer, Joshua L.

    2012-01-01

    The purpose of this analysis is to reconsider organizational replication as a strategy for large-scale school improvement: a strategy that features a "hub" organization collaborating with "outlet" schools to enact school-wide designs for improvement. To do so, we synthesize a leading line of research on commercial replication to construct a…

  2. First Mile Challenges for Large-Scale IoT

    KAUST Repository

    Bader, Ahmed; Elsawy, Hesham; Gharbieh, Mohammad; Alouini, Mohamed-Slim; Adinoyi, Abdulkareem; Alshaalan, Furaih

    2017-01-01

    The Internet of Things is large-scale by nature. This is not only manifested by the large number of connected devices, but also by the sheer scale of spatial traffic intensity that must be accommodated, primarily in the uplink direction. To that end

  3. VESPA: Very large-scale Evolutionary and Selective Pressure Analyses

    Directory of Open Access Journals (Sweden)

    Andrew E. Webb

    2017-06-01

    Full Text Available Background Large-scale molecular evolutionary analyses of protein coding sequences requires a number of preparatory inter-related steps from finding gene families, to generating alignments and phylogenetic trees and assessing selective pressure variation. Each phase of these analyses can represent significant challenges, particularly when working with entire proteomes (all protein coding sequences in a genome from a large number of species. Methods We present VESPA, software capable of automating a selective pressure analysis using codeML in addition to the preparatory analyses and summary statistics. VESPA is written in python and Perl and is designed to run within a UNIX environment. Results We have benchmarked VESPA and our results show that the method is consistent, performs well on both large scale and smaller scale datasets, and produces results in line with previously published datasets. Discussion Large-scale gene family identification, sequence alignment, and phylogeny reconstruction are all important aspects of large-scale molecular evolutionary analyses. VESPA provides flexible software for simplifying these processes along with downstream selective pressure variation analyses. The software automatically interprets results from codeML and produces simplified summary files to assist the user in better understanding the results. VESPA may be found at the following website: http://www.mol-evol.org/VESPA.

  4. Technologies and challenges in large-scale phosphoproteomics

    DEFF Research Database (Denmark)

    Engholm-Keller, Kasper; Larsen, Martin Røssel

    2013-01-01

    become the main technique for discovery and characterization of phosphoproteins in a nonhypothesis driven fashion. In this review, we describe methods for state-of-the-art MS-based analysis of protein phosphorylation as well as the strategies employed in large-scale phosphoproteomic experiments...... with focus on the various challenges and limitations this field currently faces....

  5. Solving Large Scale Crew Scheduling Problems in Practice

    NARCIS (Netherlands)

    E.J.W. Abbink (Erwin); L. Albino; T.A.B. Dollevoet (Twan); D. Huisman (Dennis); J. Roussado; R.L. Saldanha

    2010-01-01

    textabstractThis paper deals with large-scale crew scheduling problems arising at the Dutch railway operator, Netherlands Railways (NS). NS operates about 30,000 trains a week. All these trains need a driver and a certain number of guards. Some labor rules restrict the duties of a certain crew base

  6. The large scale microwave background anisotropy in decaying particle cosmology

    International Nuclear Information System (INIS)

    Panek, M.

    1987-06-01

    We investigate the large-scale anisotropy of the microwave background radiation in cosmological models with decaying particles. The observed value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z/sub d/ < 3-5. 12 refs., 2 figs

  7. Dual Decomposition for Large-Scale Power Balancing

    DEFF Research Database (Denmark)

    Halvgaard, Rasmus; Jørgensen, John Bagterp; Vandenberghe, Lieven

    2013-01-01

    Dual decomposition is applied to power balancing of exible thermal storage units. The centralized large-scale problem is decomposed into smaller subproblems and solved locallyby each unit in the Smart Grid. Convergence is achieved by coordinating the units consumption through a negotiation...

  8. Evaluation of Large-scale Public Sector Reforms

    DEFF Research Database (Denmark)

    Breidahl, Karen Nielsen; Gjelstrup, Gunnar; Hansen, Hanne Foss

    2017-01-01

    and more delimited policy areas take place. In our analysis we apply four governance perspectives (rational-instrumental, rational-interest based, institutional-cultural and a chaos perspective) in a comparative analysis of the evaluations of two large-scale public sector reforms in Denmark and Norway. We...

  9. Assessment of climate change impacts on rainfall using large scale ...

    Indian Academy of Sciences (India)

    Many of the applied techniques in water resources management can be directly or indirectly influenced by ... is based on large scale climate signals data around the world. In order ... predictand relationships are often very complex. .... constraints to solve the optimization problem. ..... social, and environmental sustainability.

  10. Factors Influencing Uptake of a Large Scale Curriculum Innovation.

    Science.gov (United States)

    Adey, Philip S.

    Educational research has all too often failed to be implemented on a large-scale basis. This paper describes the multiplier effect of a professional development program for teachers and for trainers in the United Kingdom, and how that program was developed, monitored, and evaluated. Cognitive Acceleration through Science Education (CASE) is a…

  11. ability in Large Scale Land Acquisitions in Kenya

    International Development Research Centre (IDRC) Digital Library (Canada)

    Corey Piccioni

    Kenya's national planning strategy, Vision 2030. Agri- culture, natural resource exploitation, and infrastruc- ... sitions due to high levels of poverty and unclear or in- secure land tenure rights in Kenya. Inadequate social ... lease to a private company over the expansive Yala. Swamp to undertake large-scale irrigation farming.

  12. New Visions for Large Scale Networks: Research and Applications

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — This paper documents the findings of the March 12-14, 2001 Workshop on New Visions for Large-Scale Networks: Research and Applications. The workshops objectives were...

  13. Large-scale silviculture experiments of western Oregon and Washington.

    Science.gov (United States)

    Nathan J. Poage; Paul D. Anderson

    2007-01-01

    We review 12 large-scale silviculture experiments (LSSEs) in western Washington and Oregon with which the Pacific Northwest Research Station of the USDA Forest Service is substantially involved. We compiled and arrayed information about the LSSEs as a series of matrices in a relational database, which is included on the compact disc published with this report and...

  14. Participatory Design and the Challenges of Large-Scale Systems

    DEFF Research Database (Denmark)

    Simonsen, Jesper; Hertzum, Morten

    2008-01-01

    With its 10th biannual anniversary conference, Participatory Design (PD) is leaving its teens and must now be considered ready to join the adult world. In this article we encourage the PD community to think big: PD should engage in large-scale information-systems development and opt for a PD...

  15. The tropospheric biennial oscillation defined by a biennial mode of sea surface temperature and its impact on the atmospheric circulation and precipitation in the tropical eastern Indo-western Pacific region

    Science.gov (United States)

    Kim, Jinju; Kim, Kwang-Yul

    2016-10-01

    Temporal and spatial patterns of anomalous atmospheric circulation and precipitation over the Indo-Pacific region are analyzed in conjunction with the Tropospheric Biennial Oscillation as represented by the biennial mode of sea surface temperature anomalies (SSTA). The biennial components of key variables are identified independently of other variability via CSEOF analysis. Then, its impact on the Asian-Australian monsoon is examined. The biennial mode exhibits a seasonally distinctive atmospheric response over the tropical eastern Indo-western Pacific (EIWP) region (90°-150°E, 20°S-20°N). In boreal summer, local meridional circulation is a distinguishing characteristic over the tropical EIWP region, whereas a meridionally expanded branch of intensified zonal circulation develops in austral summer. Temporally varying evolution and distinct timing of SSTA phase transition in the Indian and Pacific Oceans is considered a main factor for this variation of circulation in the tropical EIWP region. The impact of the biennial mode is not the same between the two seasons, with different impacts over ocean areas in Asian monsoon and Australian monsoon regions.

  16. Shallow and Deep Latent Heating Modes Over Tropical Oceans Observed with TRMM PR Spectral Latent Heating Data

    Science.gov (United States)

    Takayabu, Yukari N.; Shige, Shoichi; Tao, Wei-Kuo; Hirota, Nagio

    2010-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. Three-dimensional distributions of latent heating estimated from Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR)utilizing the Spectral Latent Heating (SLH) algorithm are analyzed. Mass-weighted and vertically integrated latent heating averaged over the tropical oceans is estimated as approx.72.6 J/s (approx.2.51 mm/day), and that over tropical land is approx.73.7 J/s (approx.2.55 mm/day), for 30degN-30degS. It is shown that non-drizzle precipitation over tropical and subtropical oceans consists of two dominant modes of rainfall systems, deep systems and congestus. A rough estimate of shallow mode contribution against the total heating is about 46.7 % for the average tropical oceans, which is substantially larger than 23.7 % over tropical land. While cumulus congestus heating linearly correlates with the SST, deep mode is dynamically bounded by large-scale subsidence. It is notable that substantial amount of rain, as large as 2.38 mm day-1 in average, is brought from congestus clouds under the large-scale subsiding circulation. It is also notable that even in the region with SST warmer than 28 oC, large-scale subsidence effectively suppresses the deep convection, remaining the heating by congestus clouds. Our results support that the entrainment of mid-to-lower-tropospheric dry air, which accompanies the large-scale

  17. GAIA: A WINDOW TO LARGE-SCALE MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Nusser, Adi [Physics Department and the Asher Space Science Institute-Technion, Haifa 32000 (Israel); Branchini, Enzo [Department of Physics, Universita Roma Tre, Via della Vasca Navale 84, 00146 Rome (Italy); Davis, Marc, E-mail: adi@physics.technion.ac.il, E-mail: branchin@fis.uniroma3.it, E-mail: mdavis@berkeley.edu [Departments of Astronomy and Physics, University of California, Berkeley, CA 94720 (United States)

    2012-08-10

    Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, because of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.

  18. Large-scale innovation and change in UK higher education

    Directory of Open Access Journals (Sweden)

    Stephen Brown

    2013-09-01

    Full Text Available This paper reflects on challenges universities face as they respond to change. It reviews current theories and models of change management, discusses why universities are particularly difficult environments in which to achieve large scale, lasting change and reports on a recent attempt by the UK JISC to enable a range of UK universities to employ technology to deliver such changes. Key lessons that emerged from these experiences are reviewed covering themes of pervasiveness, unofficial systems, project creep, opposition, pressure to deliver, personnel changes and technology issues. The paper argues that collaborative approaches to project management offer greater prospects of effective large-scale change in universities than either management-driven top-down or more champion-led bottom-up methods. It also argues that while some diminution of control over project outcomes is inherent in this approach, this is outweighed by potential benefits of lasting and widespread adoption of agreed changes.

  19. Measuring Cosmic Expansion and Large Scale Structure with Destiny

    Science.gov (United States)

    Benford, Dominic J.; Lauer, Tod R.

    2007-01-01

    Destiny is a simple, direct, low cost mission to determine the properties of dark energy by obtaining a cosmologically deep supernova (SN) type Ia Hubble diagram and by measuring the large-scale mass power spectrum over time. Its science instrument is a 1.65m space telescope, featuring a near-infrared survey camera/spectrometer with a large field of view. During its first two years, Destiny will detect, observe, and characterize 23000 SN Ia events over the redshift interval 0.4Destiny will be used in its third year as a high resolution, wide-field imager to conduct a weak lensing survey covering >lo00 square degrees to measure the large-scale mass power spectrum. The combination of surveys is much more powerful than either technique on its own, and will have over an order of magnitude greater sensitivity than will be provided by ongoing ground-based projects.

  20. Volume measurement study for large scale input accountancy tank

    International Nuclear Information System (INIS)

    Uchikoshi, Seiji; Watanabe, Yuichi; Tsujino, Takeshi

    1999-01-01

    Large Scale Tank Calibration (LASTAC) facility, including an experimental tank which has the same volume and structure as the input accountancy tank of Rokkasho Reprocessing Plant (RRP) was constructed in Nuclear Material Control Center of Japan. Demonstration experiments have been carried out to evaluate a precision of solution volume measurement and to establish the procedure of highly accurate pressure measurement for a large scale tank with dip-tube bubbler probe system to be applied to the input accountancy tank of RRP. Solution volume in a tank is determined from substitution the solution level for the calibration function obtained in advance, which express a relation between the solution level and its volume in the tank. Therefore, precise solution volume measurement needs a precise calibration function that is determined carefully. The LASTAC calibration experiments using pure water showed good result in reproducibility. (J.P.N.)

  1. Prototype Vector Machine for Large Scale Semi-Supervised Learning

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Kwok, James T.; Parvin, Bahram

    2009-04-29

    Practicaldataminingrarelyfalls exactlyinto the supervisedlearning scenario. Rather, the growing amount of unlabeled data poses a big challenge to large-scale semi-supervised learning (SSL). We note that the computationalintensivenessofgraph-based SSLarises largely from the manifold or graph regularization, which in turn lead to large models that are dificult to handle. To alleviate this, we proposed the prototype vector machine (PVM), a highlyscalable,graph-based algorithm for large-scale SSL. Our key innovation is the use of"prototypes vectors" for effcient approximation on both the graph-based regularizer and model representation. The choice of prototypes are grounded upon two important criteria: they not only perform effective low-rank approximation of the kernel matrix, but also span a model suffering the minimum information loss compared with the complete model. We demonstrate encouraging performance and appealing scaling properties of the PVM on a number of machine learning benchmark data sets.

  2. Large-scale influences in near-wall turbulence.

    Science.gov (United States)

    Hutchins, Nicholas; Marusic, Ivan

    2007-03-15

    Hot-wire data acquired in a high Reynolds number facility are used to illustrate the need for adequate scale separation when considering the coherent structure in wall-bounded turbulence. It is found that a large-scale motion in the log region becomes increasingly comparable in energy to the near-wall cycle as the Reynolds number increases. Through decomposition of fluctuating velocity signals, it is shown that this large-scale motion has a distinct modulating influence on the small-scale energy (akin to amplitude modulation). Reassessment of DNS data, in light of these results, shows similar trends, with the rate and intensity of production due to the near-wall cycle subject to a modulating influence from the largest-scale motions.

  3. First Mile Challenges for Large-Scale IoT

    KAUST Repository

    Bader, Ahmed

    2017-03-16

    The Internet of Things is large-scale by nature. This is not only manifested by the large number of connected devices, but also by the sheer scale of spatial traffic intensity that must be accommodated, primarily in the uplink direction. To that end, cellular networks are indeed a strong first mile candidate to accommodate the data tsunami to be generated by the IoT. However, IoT devices are required in the cellular paradigm to undergo random access procedures as a precursor to resource allocation. Such procedures impose a major bottleneck that hinders cellular networks\\' ability to support large-scale IoT. In this article, we shed light on the random access dilemma and present a case study based on experimental data as well as system-level simulations. Accordingly, a case is built for the latent need to revisit random access procedures. A call for action is motivated by listing a few potential remedies and recommendations.

  4. Cosmic ray acceleration by large scale galactic shocks

    International Nuclear Information System (INIS)

    Cesarsky, C.J.; Lagage, P.O.

    1987-01-01

    The mechanism of diffusive shock acceleration may account for the existence of galactic cosmic rays detailed application to stellar wind shocks and especially to supernova shocks have been developed. Existing models can usually deal with the energetics or the spectral slope, but the observed energy range of cosmic rays is not explained. Therefore it seems worthwhile to examine the effect that large scale, long-lived galactic shocks may have on galactic cosmic rays, in the frame of the diffusive shock acceleration mechanism. Large scale fast shocks can only be expected to exist in the galactic halo. We consider three situations where they may arise: expansion of a supernova shock in the halo, galactic wind, galactic infall; and discuss the possible existence of these shocks and their role in accelerating cosmic rays

  5. Efficient algorithms for collaborative decision making for large scale settings

    DEFF Research Database (Denmark)

    Assent, Ira

    2011-01-01

    to bring about more effective and more efficient retrieval systems that support the users' decision making process. We sketch promising research directions for more efficient algorithms for collaborative decision making, especially for large scale systems.......Collaborative decision making is a successful approach in settings where data analysis and querying can be done interactively. In large scale systems with huge data volumes or many users, collaboration is often hindered by impractical runtimes. Existing work on improving collaboration focuses...... on avoiding redundancy for users working on the same task. While this improves the effectiveness of the user work process, the underlying query processing engine is typically considered a "black box" and left unchanged. Research in multiple query processing, on the other hand, ignores the application...

  6. Lagrangian space consistency relation for large scale structure

    International Nuclear Information System (INIS)

    Horn, Bart; Hui, Lam; Xiao, Xiao

    2015-01-01

    Consistency relations, which relate the squeezed limit of an (N+1)-point correlation function to an N-point function, are non-perturbative symmetry statements that hold even if the associated high momentum modes are deep in the nonlinear regime and astrophysically complex. Recently, Kehagias and Riotto and Peloso and Pietroni discovered a consistency relation applicable to large scale structure. We show that this can be recast into a simple physical statement in Lagrangian space: that the squeezed correlation function (suitably normalized) vanishes. This holds regardless of whether the correlation observables are at the same time or not, and regardless of whether multiple-streaming is present. The simplicity of this statement suggests that an analytic understanding of large scale structure in the nonlinear regime may be particularly promising in Lagrangian space

  7. The Large-scale Effect of Environment on Galactic Conformity

    Science.gov (United States)

    Sun, Shuangpeng; Guo, Qi; Wang, Lan; Wang, Jie; Gao, Liang; Lacey, Cedric G.; Pan, Jun

    2018-04-01

    We use a volume-limited galaxy sample from the SDSS Data Release 7 to explore the dependence of galactic conformity on the large-scale environment, measured on ˜ 4 Mpc scales. We find that the star formation activity of neighbour galaxies depends more strongly on the environment than on the activity of their primary galaxies. In under-dense regions most neighbour galaxies tend to be active, while in over-dense regions neighbour galaxies are mostly passive, regardless of the activity of their primary galaxies. At a given stellar mass, passive primary galaxies reside in higher density regions than active primary galaxies, leading to the apparently strong conformity signal. The dependence of the activity of neighbour galaxies on environment can be explained by the corresponding dependence of the fraction of satellite galaxies. Similar results are found for galaxies in a semi-analytical model, suggesting that no new physics is required to explain the observed large-scale conformity.

  8. Electron drift in a large scale solid xenon

    International Nuclear Information System (INIS)

    Yoo, J.; Jaskierny, W.F.

    2015-01-01

    A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7 cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163 K), the drift speed is 0.193 ± 0.003 cm/μs while the drift speed in the solid phase (157 K) is 0.397 ± 0.006 cm/μs at 900 V/cm over 8.0 cm of uniform electric fields. Therefore, it is demonstrated that a factor two faster electron drift speed in solid phase xenon compared to that in liquid in a large scale solid xenon

  9. Active power reserves evaluation in large scale PVPPs

    DEFF Research Database (Denmark)

    Crăciun, Bogdan-Ionut; Kerekes, Tamas; Sera, Dezso

    2013-01-01

    The present trend on investing in renewable ways of producing electricity in the detriment of conventional fossil fuel-based plants will lead to a certain point where these plants have to provide ancillary services and contribute to overall grid stability. Photovoltaic (PV) power has the fastest...... growth among all renewable energies and managed to reach high penetration levels creating instabilities which at the moment are corrected by the conventional generation. This paradigm will change in the future scenarios where most of the power is supplied by large scale renewable plants and parts...... of the ancillary services have to be shared by the renewable plants. The main focus of the proposed paper is to technically and economically analyze the possibility of having active power reserves in large scale PV power plants (PVPPs) without any auxiliary storage equipment. The provided reserves should...

  10. Real-time simulation of large-scale floods

    Science.gov (United States)

    Liu, Q.; Qin, Y.; Li, G. D.; Liu, Z.; Cheng, D. J.; Zhao, Y. H.

    2016-08-01

    According to the complex real-time water situation, the real-time simulation of large-scale floods is very important for flood prevention practice. Model robustness and running efficiency are two critical factors in successful real-time flood simulation. This paper proposed a robust, two-dimensional, shallow water model based on the unstructured Godunov- type finite volume method. A robust wet/dry front method is used to enhance the numerical stability. An adaptive method is proposed to improve the running efficiency. The proposed model is used for large-scale flood simulation on real topography. Results compared to those of MIKE21 show the strong performance of the proposed model.

  11. Some Statistics for Measuring Large-Scale Structure

    OpenAIRE

    Brandenberger, Robert H.; Kaplan, David M.; A, Stephen; Ramsey

    1993-01-01

    Good statistics for measuring large-scale structure in the Universe must be able to distinguish between different models of structure formation. In this paper, two and three dimensional ``counts in cell" statistics and a new ``discrete genus statistic" are applied to toy versions of several popular theories of structure formation: random phase cold dark matter model, cosmic string models, and global texture scenario. All three statistics appear quite promising in terms of differentiating betw...

  12. Foundations of Large-Scale Multimedia Information Management and Retrieval

    CERN Document Server

    Chang, Edward Y

    2011-01-01

    "Foundations of Large-Scale Multimedia Information Management and Retrieval - Mathematics of Perception" covers knowledge representation and semantic analysis of multimedia data and scalability in signal extraction, data mining, and indexing. The book is divided into two parts: Part I - Knowledge Representation and Semantic Analysis focuses on the key components of mathematics of perception as it applies to data management and retrieval. These include feature selection/reduction, knowledge representation, semantic analysis, distance function formulation for measuring similarity, and

  13. PKI security in large-scale healthcare networks

    OpenAIRE

    Mantas, G.; Lymberopoulos, D.; Komninos, N.

    2012-01-01

    During the past few years a lot of PKI (Public Key Infrastructures) infrastructures have been proposed for healthcare networks in order to ensure secure communication services and exchange of data among healthcare professionals. However, there is a plethora of challenges in these healthcare PKI infrastructures. Especially, there are a lot of challenges for PKI infrastructures deployed over large-scale healthcare networks. In this paper, we propose a PKI infrastructure to ensure security in a ...

  14. Experimental simulation of microinteractions in large scale explosions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Luo, R.; Yuen, W.W.; Theofanous, T.G. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

    1998-01-01

    This paper presents data and analysis of recent experiments conducted in the SIGMA-2000 facility to simulate microinteractions in large scale explosions. Specifically, the fragmentation behavior of a high temperature molten steel drop under high pressure (beyond critical) conditions are investigated. The current data demonstrate, for the first time, the effect of high pressure in suppressing the thermal effect of fragmentation under supercritical conditions. The results support the microinteractions idea, and the ESPROSE.m prediction of fragmentation rate. (author)

  15. Large-scale motions in the universe: a review

    International Nuclear Information System (INIS)

    Burstein, D.

    1990-01-01

    The expansion of the universe can be retarded in localised regions within the universe both by the presence of gravity and by non-gravitational motions generated in the post-recombination universe. The motions of galaxies thus generated are called 'peculiar motions', and the amplitudes, size scales and coherence of these peculiar motions are among the most direct records of the structure of the universe. As such, measurements of these properties of the present-day universe provide some of the severest tests of cosmological theories. This is a review of the current evidence for large-scale motions of galaxies out to a distance of ∼5000 km s -1 (in an expanding universe, distance is proportional to radial velocity). 'Large-scale' in this context refers to motions that are correlated over size scales larger than the typical sizes of groups of galaxies, up to and including the size of the volume surveyed. To orient the reader into this relatively new field of study, a short modern history is given together with an explanation of the terminology. Careful consideration is given to the data used to measure the distances, and hence the peculiar motions, of galaxies. The evidence for large-scale motions is presented in a graphical fashion, using only the most reliable data for galaxies spanning a wide range in optical properties and over the complete range of galactic environments. The kinds of systematic errors that can affect this analysis are discussed, and the reliability of these motions is assessed. The predictions of two models of large-scale motion are compared to the observations, and special emphasis is placed on those motions in which our own Galaxy directly partakes. (author)

  16. A Classification Framework for Large-Scale Face Recognition Systems

    OpenAIRE

    Zhou, Ziheng; Deravi, Farzin

    2009-01-01

    This paper presents a generic classification framework for large-scale face recognition systems. Within the framework, a data sampling strategy is proposed to tackle the data imbalance when image pairs are sampled from thousands of face images for preparing a training dataset. A modified kernel Fisher discriminant classifier is proposed to make it computationally feasible to train the kernel-based classification method using tens of thousands of training samples. The framework is tested in an...

  17. Large Scale Visual Recommendations From Street Fashion Images

    OpenAIRE

    Jagadeesh, Vignesh; Piramuthu, Robinson; Bhardwaj, Anurag; Di, Wei; Sundaresan, Neel

    2014-01-01

    We describe a completely automated large scale visual recommendation system for fashion. Our focus is to efficiently harness the availability of large quantities of online fashion images and their rich meta-data. Specifically, we propose four data driven models in the form of Complementary Nearest Neighbor Consensus, Gaussian Mixture Models, Texture Agnostic Retrieval and Markov Chain LDA for solving this problem. We analyze relative merits and pitfalls of these algorithms through extensive e...

  18. Design study on sodium cooled large-scale reactor

    International Nuclear Information System (INIS)

    Murakami, Tsutomu; Hishida, Masahiko; Kisohara, Naoyuki

    2004-07-01

    In Phase 1 of the 'Feasibility Studies on Commercialized Fast Reactor Cycle Systems (F/S)', an advanced loop type reactor has been selected as a promising concept of sodium-cooled large-scale reactor, which has a possibility to fulfill the design requirements of the F/S. In Phase 2, design improvement for further cost reduction of establishment of the plant concept has been performed. This report summarizes the results of the design study on the sodium-cooled large-scale reactor performed in JFY2003, which is the third year of Phase 2. In the JFY2003 design study, critical subjects related to safety, structural integrity and thermal hydraulics which found in the last fiscal year has been examined and the plant concept has been modified. Furthermore, fundamental specifications of main systems and components have been set and economy has been evaluated. In addition, as the interim evaluation of the candidate concept of the FBR fuel cycle is to be conducted, cost effectiveness and achievability for the development goal were evaluated and the data of the three large-scale reactor candidate concepts were prepared. As a results of this study, the plant concept of the sodium-cooled large-scale reactor has been constructed, which has a prospect to satisfy the economic goal (construction cost: less than 200,000 yens/kWe, etc.) and has a prospect to solve the critical subjects. From now on, reflecting the results of elemental experiments, the preliminary conceptual design of this plant will be preceded toward the selection for narrowing down candidate concepts at the end of Phase 2. (author)

  19. Design study on sodium-cooled large-scale reactor

    International Nuclear Information System (INIS)

    Shimakawa, Yoshio; Nibe, Nobuaki; Hori, Toru

    2002-05-01

    In Phase 1 of the 'Feasibility Study on Commercialized Fast Reactor Cycle Systems (F/S)', an advanced loop type reactor has been selected as a promising concept of sodium-cooled large-scale reactor, which has a possibility to fulfill the design requirements of the F/S. In Phase 2 of the F/S, it is planed to precede a preliminary conceptual design of a sodium-cooled large-scale reactor based on the design of the advanced loop type reactor. Through the design study, it is intended to construct such a plant concept that can show its attraction and competitiveness as a commercialized reactor. This report summarizes the results of the design study on the sodium-cooled large-scale reactor performed in JFY2001, which is the first year of Phase 2. In the JFY2001 design study, a plant concept has been constructed based on the design of the advanced loop type reactor, and fundamental specifications of main systems and components have been set. Furthermore, critical subjects related to safety, structural integrity, thermal hydraulics, operability, maintainability and economy have been examined and evaluated. As a result of this study, the plant concept of the sodium-cooled large-scale reactor has been constructed, which has a prospect to satisfy the economic goal (construction cost: less than 200,000yens/kWe, etc.) and has a prospect to solve the critical subjects. From now on, reflecting the results of elemental experiments, the preliminary conceptual design of this plant will be preceded toward the selection for narrowing down candidate concepts at the end of Phase 2. (author)

  20. Large-Scale Optimization for Bayesian Inference in Complex Systems

    Energy Technology Data Exchange (ETDEWEB)

    Willcox, Karen [MIT; Marzouk, Youssef [MIT

    2013-11-12

    The SAGUARO (Scalable Algorithms for Groundwater Uncertainty Analysis and Robust Optimization) Project focused on the development of scalable numerical algorithms for large-scale Bayesian inversion in complex systems that capitalize on advances in large-scale simulation-based optimization and inversion methods. The project was a collaborative effort among MIT, the University of Texas at Austin, Georgia Institute of Technology, and Sandia National Laboratories. The research was directed in three complementary areas: efficient approximations of the Hessian operator, reductions in complexity of forward simulations via stochastic spectral approximations and model reduction, and employing large-scale optimization concepts to accelerate sampling. The MIT--Sandia component of the SAGUARO Project addressed the intractability of conventional sampling methods for large-scale statistical inverse problems by devising reduced-order models that are faithful to the full-order model over a wide range of parameter values; sampling then employs the reduced model rather than the full model, resulting in very large computational savings. Results indicate little effect on the computed posterior distribution. On the other hand, in the Texas--Georgia Tech component of the project, we retain the full-order model, but exploit inverse problem structure (adjoint-based gradients and partial Hessian information of the parameter-to-observation map) to implicitly extract lower dimensional information on the posterior distribution; this greatly speeds up sampling methods, so that fewer sampling points are needed. We can think of these two approaches as ``reduce then sample'' and ``sample then reduce.'' In fact, these two approaches are complementary, and can be used in conjunction with each other. Moreover, they both exploit deterministic inverse problem structure, in the form of adjoint-based gradient and Hessian information of the underlying parameter-to-observation map, to

  1. NASA: Assessments of Selected Large-Scale Projects

    Science.gov (United States)

    2011-03-01

    REPORT DATE MAR 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Assessments Of Selected Large-Scale Projects...Volatile EvolutioN MEP Mars Exploration Program MIB Mishap Investigation Board MMRTG Multi Mission Radioisotope Thermoelectric Generator MMS Magnetospheric...probes designed to explore the Martian surface, to satellites equipped with advanced sensors to study the earth , to telescopes intended to explore the

  2. Perturbation theory instead of large scale shell model calculations

    International Nuclear Information System (INIS)

    Feldmeier, H.; Mankos, P.

    1977-01-01

    Results of large scale shell model calculations for (sd)-shell nuclei are compared with a perturbation theory provides an excellent approximation when the SU(3)-basis is used as a starting point. The results indicate that perturbation theory treatment in an SU(3)-basis including 2hω excitations should be preferable to a full diagonalization within the (sd)-shell. (orig.) [de

  3. Primordial large-scale electromagnetic fields from gravitoelectromagnetic inflation

    Energy Technology Data Exchange (ETDEWEB)

    Membiela, Federico Agustin [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, (7600) Mar del Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)], E-mail: membiela@mdp.edu.ar; Bellini, Mauricio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, (7600) Mar del Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)], E-mail: mbellini@mdp.edu.ar

    2009-04-20

    We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant {lambda}{sub 0}. Using the gravitoelectromagnetic inflationary formalism with A{sub 0}=0, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is naturally non-conformally invariant.

  4. Primordial large-scale electromagnetic fields from gravitoelectromagnetic inflation

    Science.gov (United States)

    Membiela, Federico Agustín; Bellini, Mauricio

    2009-04-01

    We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant Λ0. Using the gravitoelectromagnetic inflationary formalism with A0 = 0, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is naturally non-conformally invariant.

  5. Primordial large-scale electromagnetic fields from gravitoelectromagnetic inflation

    International Nuclear Information System (INIS)

    Membiela, Federico Agustin; Bellini, Mauricio

    2009-01-01

    We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant Λ 0 . Using the gravitoelectromagnetic inflationary formalism with A 0 =0, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is naturally non-conformally invariant.

  6. Rotation invariant fast features for large-scale recognition

    Science.gov (United States)

    Takacs, Gabriel; Chandrasekhar, Vijay; Tsai, Sam; Chen, David; Grzeszczuk, Radek; Girod, Bernd

    2012-10-01

    We present an end-to-end feature description pipeline which uses a novel interest point detector and Rotation- Invariant Fast Feature (RIFF) descriptors. The proposed RIFF algorithm is 15× faster than SURF1 while producing large-scale retrieval results that are comparable to SIFT.2 Such high-speed features benefit a range of applications from Mobile Augmented Reality (MAR) to web-scale image retrieval and analysis.

  7. Concurrent Programming Using Actors: Exploiting Large-Scale Parallelism,

    Science.gov (United States)

    1985-10-07

    ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK* Artificial Inteligence Laboratory AREA Is WORK UNIT NUMBERS 545 Technology Square...D-R162 422 CONCURRENT PROGRMMIZNG USING f"OS XL?ITP TEH l’ LARGE-SCALE PARALLELISH(U) NASI AC E Al CAMBRIDGE ARTIFICIAL INTELLIGENCE L. G AGHA ET AL...RESOLUTION TEST CHART N~ATIONAL BUREAU OF STANDA.RDS - -96 A -E. __ _ __ __’ .,*- - -- •. - MASSACHUSETTS INSTITUTE OF TECHNOLOGY ARTIFICIAL

  8. On a Game of Large-Scale Projects Competition

    Science.gov (United States)

    Nikonov, Oleg I.; Medvedeva, Marina A.

    2009-09-01

    The paper is devoted to game-theoretical control problems motivated by economic decision making situations arising in realization of large-scale projects, such as designing and putting into operations the new gas or oil pipelines. A non-cooperative two player game is considered with payoff functions of special type for which standard existence theorems and algorithms for searching Nash equilibrium solutions are not applicable. The paper is based on and develops the results obtained in [1]-[5].

  9. The Phoenix series large scale LNG pool fire experiments.

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Richard B.; Jensen, Richard Pearson; Demosthenous, Byron; Luketa, Anay Josephine; Ricks, Allen Joseph; Hightower, Marion Michael; Blanchat, Thomas K.; Helmick, Paul H.; Tieszen, Sheldon Robert; Deola, Regina Anne; Mercier, Jeffrey Alan; Suo-Anttila, Jill Marie; Miller, Timothy J.

    2010-12-01

    The increasing demand for natural gas could increase the number and frequency of Liquefied Natural Gas (LNG) tanker deliveries to ports across the United States. Because of the increasing number of shipments and the number of possible new facilities, concerns about the potential safety of the public and property from an accidental, and even more importantly intentional spills, have increased. While improvements have been made over the past decade in assessing hazards from LNG spills, the existing experimental data is much smaller in size and scale than many postulated large accidental and intentional spills. Since the physics and hazards from a fire change with fire size, there are concerns about the adequacy of current hazard prediction techniques for large LNG spills and fires. To address these concerns, Congress funded the Department of Energy (DOE) in 2008 to conduct a series of laboratory and large-scale LNG pool fire experiments at Sandia National Laboratories (Sandia) in Albuquerque, New Mexico. This report presents the test data and results of both sets of fire experiments. A series of five reduced-scale (gas burner) tests (yielding 27 sets of data) were conducted in 2007 and 2008 at Sandia's Thermal Test Complex (TTC) to assess flame height to fire diameter ratios as a function of nondimensional heat release rates for extrapolation to large-scale LNG fires. The large-scale LNG pool fire experiments were conducted in a 120 m diameter pond specially designed and constructed in Sandia's Area III large-scale test complex. Two fire tests of LNG spills of 21 and 81 m in diameter were conducted in 2009 to improve the understanding of flame height, smoke production, and burn rate and therefore the physics and hazards of large LNG spills and fires.

  10. Large scale 2D spectral compressed sensing in continuous domain

    KAUST Repository

    Cai, Jian-Feng

    2017-06-20

    We consider the problem of spectral compressed sensing in continuous domain, which aims to recover a 2-dimensional spectrally sparse signal from partially observed time samples. The signal is assumed to be a superposition of s complex sinusoids. We propose a semidefinite program for the 2D signal recovery problem. Our model is able to handle large scale 2D signals of size 500 × 500, whereas traditional approaches only handle signals of size around 20 × 20.

  11. Large scale 2D spectral compressed sensing in continuous domain

    KAUST Repository

    Cai, Jian-Feng; Xu, Weiyu; Yang, Yang

    2017-01-01

    We consider the problem of spectral compressed sensing in continuous domain, which aims to recover a 2-dimensional spectrally sparse signal from partially observed time samples. The signal is assumed to be a superposition of s complex sinusoids. We propose a semidefinite program for the 2D signal recovery problem. Our model is able to handle large scale 2D signals of size 500 × 500, whereas traditional approaches only handle signals of size around 20 × 20.

  12. Large-scale nuclear energy from the thorium cycle

    International Nuclear Information System (INIS)

    Lewis, W.B.; Duret, M.F.; Craig, D.S.; Veeder, J.I.; Bain, A.S.

    1973-02-01

    The thorium fuel cycle in CANDU (Canada Deuterium Uranium) reactors challenges breeders and fusion as the simplest means of meeting the world's large-scale demands for energy for centuries. Thorium oxide fuel allows high power density with excellent neutron economy. The combination of thorium fuel with organic caloporteur promises easy maintenance and high availability of the whole plant. The total fuelling cost including charges on the inventory is estimated to be attractively low. (author) [fr

  13. Large scale particle image velocimetry with helium filled soap bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Bosbach, Johannes; Kuehn, Matthias; Wagner, Claus [German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Goettingen (Germany)

    2009-03-15

    The application of particle image velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of computational fluid dynamics simulations. (orig.)

  14. Fast, large-scale hologram calculation in wavelet domain

    Science.gov (United States)

    Shimobaba, Tomoyoshi; Matsushima, Kyoji; Takahashi, Takayuki; Nagahama, Yuki; Hasegawa, Satoki; Sano, Marie; Hirayama, Ryuji; Kakue, Takashi; Ito, Tomoyoshi

    2018-04-01

    We propose a large-scale hologram calculation using WAvelet ShrinkAge-Based superpositIon (WASABI), a wavelet transform-based algorithm. An image-type hologram calculated using the WASABI method is printed on a glass substrate with the resolution of 65 , 536 × 65 , 536 pixels and a pixel pitch of 1 μm. The hologram calculation time amounts to approximately 354 s on a commercial CPU, which is approximately 30 times faster than conventional methods.

  15. Evolutionary leap in large-scale flood risk assessment needed

    OpenAIRE

    Vorogushyn, Sergiy; Bates, Paul D.; de Bruijn, Karin; Castellarin, Attilio; Kreibich, Heidi; Priest, Sally J.; Schröter, Kai; Bagli, Stefano; Blöschl, Günter; Domeneghetti, Alessio; Gouldby, Ben; Klijn, Frans; Lammersen, Rita; Neal, Jeffrey C.; Ridder, Nina

    2018-01-01

    Current approaches for assessing large-scale flood risks contravene the fundamental principles of the flood risk system functioning because they largely ignore basic interactions and feedbacks between atmosphere, catchments, river-floodplain systems and socio-economic processes. As a consequence, risk analyses are uncertain and might be biased. However, reliable risk estimates are required for prioritizing national investments in flood risk mitigation or for appraisal and management of insura...

  16. Large scale particle image velocimetry with helium filled soap bubbles

    Science.gov (United States)

    Bosbach, Johannes; Kühn, Matthias; Wagner, Claus

    2009-03-01

    The application of Particle Image Velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of Computational Fluid Dynamics simulations.

  17. Large-scale Health Information Database and Privacy Protection*1

    OpenAIRE

    YAMAMOTO, Ryuichi

    2016-01-01

    Japan was once progressive in the digitalization of healthcare fields but unfortunately has fallen behind in terms of the secondary use of data for public interest. There has recently been a trend to establish large-scale health databases in the nation, and a conflict between data use for public interest and privacy protection has surfaced as this trend has progressed. Databases for health insurance claims or for specific health checkups and guidance services were created according to the law...

  18. Large-scale preparation of hollow graphitic carbon nanospheres

    International Nuclear Information System (INIS)

    Feng, Jun; Li, Fu; Bai, Yu-Jun; Han, Fu-Dong; Qi, Yong-Xin; Lun, Ning; Lu, Xi-Feng

    2013-01-01

    Hollow graphitic carbon nanospheres (HGCNSs) were synthesized on large scale by a simple reaction between glucose and Mg at 550 °C in an autoclave. Characterization by X-ray diffraction, Raman spectroscopy and transmission electron microscopy demonstrates the formation of HGCNSs with an average diameter of 10 nm or so and a wall thickness of a few graphenes. The HGCNSs exhibit a reversible capacity of 391 mAh g −1 after 60 cycles when used as anode materials for Li-ion batteries. -- Graphical abstract: Hollow graphitic carbon nanospheres could be prepared on large scale by the simple reaction between glucose and Mg at 550 °C, which exhibit superior electrochemical performance to graphite. Highlights: ► Hollow graphitic carbon nanospheres (HGCNSs) were prepared on large scale at 550 °C ► The preparation is simple, effective and eco-friendly. ► The in situ yielded MgO nanocrystals promote the graphitization. ► The HGCNSs exhibit superior electrochemical performance to graphite.

  19. Homogenization of Large-Scale Movement Models in Ecology

    Science.gov (United States)

    Garlick, M.J.; Powell, J.A.; Hooten, M.B.; McFarlane, L.R.

    2011-01-01

    A difficulty in using diffusion models to predict large scale animal population dispersal is that individuals move differently based on local information (as opposed to gradients) in differing habitat types. This can be accommodated by using ecological diffusion. However, real environments are often spatially complex, limiting application of a direct approach. Homogenization for partial differential equations has long been applied to Fickian diffusion (in which average individual movement is organized along gradients of habitat and population density). We derive a homogenization procedure for ecological diffusion and apply it to a simple model for chronic wasting disease in mule deer. Homogenization allows us to determine the impact of small scale (10-100 m) habitat variability on large scale (10-100 km) movement. The procedure generates asymptotic equations for solutions on the large scale with parameters defined by small-scale variation. The simplicity of this homogenization procedure is striking when compared to the multi-dimensional homogenization procedure for Fickian diffusion,and the method will be equally straightforward for more complex models. ?? 2010 Society for Mathematical Biology.

  20. Multiresolution comparison of precipitation datasets for large-scale models

    Science.gov (United States)

    Chun, K. P.; Sapriza Azuri, G.; Davison, B.; DeBeer, C. M.; Wheater, H. S.

    2014-12-01

    Gridded precipitation datasets are crucial for driving large-scale models which are related to weather forecast and climate research. However, the quality of precipitation products is usually validated individually. Comparisons between gridded precipitation products along with ground observations provide another avenue for investigating how the precipitation uncertainty would affect the performance of large-scale models. In this study, using data from a set of precipitation gauges over British Columbia and Alberta, we evaluate several widely used North America gridded products including the Canadian Gridded Precipitation Anomalies (CANGRD), the National Center for Environmental Prediction (NCEP) reanalysis, the Water and Global Change (WATCH) project, the thin plate spline smoothing algorithms (ANUSPLIN) and Canadian Precipitation Analysis (CaPA). Based on verification criteria for various temporal and spatial scales, results provide an assessment of possible applications for various precipitation datasets. For long-term climate variation studies (~100 years), CANGRD, NCEP, WATCH and ANUSPLIN have different comparative advantages in terms of their resolution and accuracy. For synoptic and mesoscale precipitation patterns, CaPA provides appealing performance of spatial coherence. In addition to the products comparison, various downscaling methods are also surveyed to explore new verification and bias-reduction methods for improving gridded precipitation outputs for large-scale models.

  1. BILGO: Bilateral greedy optimization for large scale semidefinite programming

    KAUST Repository

    Hao, Zhifeng

    2013-10-03

    Many machine learning tasks (e.g. metric and manifold learning problems) can be formulated as convex semidefinite programs. To enable the application of these tasks on a large-scale, scalability and computational efficiency are considered as desirable properties for a practical semidefinite programming algorithm. In this paper, we theoretically analyze a new bilateral greedy optimization (denoted BILGO) strategy in solving general semidefinite programs on large-scale datasets. As compared to existing methods, BILGO employs a bilateral search strategy during each optimization iteration. In such an iteration, the current semidefinite matrix solution is updated as a bilateral linear combination of the previous solution and a suitable rank-1 matrix, which can be efficiently computed from the leading eigenvector of the descent direction at this iteration. By optimizing for the coefficients of the bilateral combination, BILGO reduces the cost function in every iteration until the KKT conditions are fully satisfied, thus, it tends to converge to a global optimum. In fact, we prove that BILGO converges to the global optimal solution at a rate of O(1/k), where k is the iteration counter. The algorithm thus successfully combines the efficiency of conventional rank-1 update algorithms and the effectiveness of gradient descent. Moreover, BILGO can be easily extended to handle low rank constraints. To validate the effectiveness and efficiency of BILGO, we apply it to two important machine learning tasks, namely Mahalanobis metric learning and maximum variance unfolding. Extensive experimental results clearly demonstrate that BILGO can solve large-scale semidefinite programs efficiently.

  2. Human visual system automatically represents large-scale sequential regularities.

    Science.gov (United States)

    Kimura, Motohiro; Widmann, Andreas; Schröger, Erich

    2010-03-04

    Our brain recordings reveal that large-scale sequential regularities defined across non-adjacent stimuli can be automatically represented in visual sensory memory. To show that, we adopted an auditory paradigm developed by Sussman, E., Ritter, W., and Vaughan, H. G. Jr. (1998). Predictability of stimulus deviance and the mismatch negativity. NeuroReport, 9, 4167-4170, Sussman, E., and Gumenyuk, V. (2005). Organization of sequential sounds in auditory memory. NeuroReport, 16, 1519-1523 to the visual domain by presenting task-irrelevant infrequent luminance-deviant stimuli (D, 20%) inserted among task-irrelevant frequent stimuli being of standard luminance (S, 80%) in randomized (randomized condition, SSSDSSSSSDSSSSD...) and fixed manners (fixed condition, SSSSDSSSSDSSSSD...). Comparing the visual mismatch negativity (visual MMN), an event-related brain potential (ERP) index of memory-mismatch processes in human visual sensory system, revealed that visual MMN elicited by deviant stimuli was reduced in the fixed compared to the randomized condition. Thus, the large-scale sequential regularity being present in the fixed condition (SSSSD) must have been represented in visual sensory memory. Interestingly, this effect did not occur in conditions with stimulus-onset asynchronies (SOAs) of 480 and 800 ms but was confined to the 160-ms SOA condition supporting the hypothesis that large-scale regularity extraction was based on perceptual grouping of the five successive stimuli defining the regularity. 2010 Elsevier B.V. All rights reserved.

  3. Large-scale preparation of hollow graphitic carbon nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jun; Li, Fu [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bai, Yu-Jun, E-mail: byj97@126.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); State Key laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Han, Fu-Dong; Qi, Yong-Xin; Lun, Ning [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Lu, Xi-Feng [Lunan Institute of Coal Chemical Engineering, Jining 272000 (China)

    2013-01-15

    Hollow graphitic carbon nanospheres (HGCNSs) were synthesized on large scale by a simple reaction between glucose and Mg at 550 Degree-Sign C in an autoclave. Characterization by X-ray diffraction, Raman spectroscopy and transmission electron microscopy demonstrates the formation of HGCNSs with an average diameter of 10 nm or so and a wall thickness of a few graphenes. The HGCNSs exhibit a reversible capacity of 391 mAh g{sup -1} after 60 cycles when used as anode materials for Li-ion batteries. -- Graphical abstract: Hollow graphitic carbon nanospheres could be prepared on large scale by the simple reaction between glucose and Mg at 550 Degree-Sign C, which exhibit superior electrochemical performance to graphite. Highlights: Black-Right-Pointing-Pointer Hollow graphitic carbon nanospheres (HGCNSs) were prepared on large scale at 550 Degree-Sign C Black-Right-Pointing-Pointer The preparation is simple, effective and eco-friendly. Black-Right-Pointing-Pointer The in situ yielded MgO nanocrystals promote the graphitization. Black-Right-Pointing-Pointer The HGCNSs exhibit superior electrochemical performance to graphite.

  4. Study of a large scale neutron measurement channel

    International Nuclear Information System (INIS)

    Amarouayache, Anissa; Ben Hadid, Hayet.

    1982-12-01

    A large scale measurement channel allows the processing of the signal coming from an unique neutronic sensor, during three different running modes: impulses, fluctuations and current. The study described in this note includes three parts: - A theoretical study of the large scale channel and its brief description are given. The results obtained till now in that domain are presented. - The fluctuation mode is thoroughly studied and the improvements to be done are defined. The study of a fluctuation linear channel with an automatic commutation of scales is described and the results of the tests are given. In this large scale channel, the method of data processing is analogical. - To become independent of the problems generated by the use of a an analogical processing of the fluctuation signal, a digital method of data processing is tested. The validity of that method is improved. The results obtained on a test system realized according to this method are given and a preliminary plan for further research is defined [fr

  5. Critical thinking, politics on a large scale and media democracy

    Directory of Open Access Journals (Sweden)

    José Antonio IBÁÑEZ-MARTÍN

    2015-06-01

    Full Text Available The first approximation to the social current reality offers us numerous motives for the worry. The spectacle of violence and of immorality can scare us easily. But more worrying still it is to verify that the horizon of conviviality, peace and wellbeing that Europe had been developing from the Treaty of Rome of 1957 has compromised itself seriously for the economic crisis. Today we are before an assault to the democratic politics, which is qualified, on the part of the media democracy, as an exhausted system, which is required to be changed into a new and great politics, a politics on a large scale. The article analyses the concept of a politics on a large scale, primarily attending to Nietzsche, and noting its union with the great philosophy and the great education. The study of the texts of Nietzsche leads us to the conclusion of how in them we often find an interesting analysis of the problems and a misguided proposal for solutions. We cannot think to suggest solutions to all the problems, but we outline various proposals about changes of political activity, that reasonably are defended from the media democracy. In conclusion, we point out that a politics on a large scale requires statesmen, able to suggest modes of life in common that can structure a long-term coexistence.

  6. Geospatial Optimization of Siting Large-Scale Solar Projects

    Energy Technology Data Exchange (ETDEWEB)

    Macknick, Jordan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Quinby, Ted [National Renewable Energy Lab. (NREL), Golden, CO (United States); Caulfield, Emmet [Stanford Univ., CA (United States); Gerritsen, Margot [Stanford Univ., CA (United States); Diffendorfer, Jay [U.S. Geological Survey, Boulder, CO (United States); Haines, Seth [U.S. Geological Survey, Boulder, CO (United States)

    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. Parallel clustering algorithm for large-scale biological data sets.

    Science.gov (United States)

    Wang, Minchao; Zhang, Wu; Ding, Wang; Dai, Dongbo; Zhang, Huiran; Xie, Hao; Chen, Luonan; Guo, Yike; Xie, Jiang

    2014-01-01

    Recent explosion of biological data brings a great challenge for the traditional clustering algorithms. With increasing scale of data sets, much larger memory and longer runtime are required for the cluster identification problems. The affinity propagation algorithm outperforms many other classical clustering algorithms and is widely applied into the biological researches. However, the time and space complexity become a great bottleneck when handling the large-scale data sets. Moreover, the similarity matrix, whose constructing procedure takes long runtime, is required before running the affinity propagation algorithm, since the algorithm clusters data sets based on the similarities between data pairs. Two types of parallel architectures are proposed in this paper to accelerate the similarity matrix constructing procedure and the affinity propagation algorithm. The memory-shared architecture is used to construct the similarity matrix, and the distributed system is taken for the affinity propagation algorithm, because of its large memory size and great computing capacity. An appropriate way of data partition and reduction is designed in our method, in order to minimize the global communication cost among processes. A speedup of 100 is gained with 128 cores. The runtime is reduced from serval hours to a few seconds, which indicates that parallel algorithm is capable of handling large-scale data sets effectively. The parallel affinity propagation also achieves a good performance when clustering large-scale gene data (microarray) and detecting families in large protein superfamilies.

  8. Accelerating large-scale phase-field simulations with GPU

    Directory of Open Access Journals (Sweden)

    Xiaoming Shi

    2017-10-01

    Full Text Available A new package for accelerating large-scale phase-field simulations was developed by using GPU based on the semi-implicit Fourier method. The package can solve a variety of equilibrium equations with different inhomogeneity including long-range elastic, magnetostatic, and electrostatic interactions. Through using specific algorithm in Compute Unified Device Architecture (CUDA, Fourier spectral iterative perturbation method was integrated in GPU package. The Allen-Cahn equation, Cahn-Hilliard equation, and phase-field model with long-range interaction were solved based on the algorithm running on GPU respectively to test the performance of the package. From the comparison of the calculation results between the solver executed in single CPU and the one on GPU, it was found that the speed on GPU is enormously elevated to 50 times faster. The present study therefore contributes to the acceleration of large-scale phase-field simulations and provides guidance for experiments to design large-scale functional devices.

  9. Problems of large-scale vertically-integrated aquaculture

    Energy Technology Data Exchange (ETDEWEB)

    Webber, H H; Riordan, P F

    1976-01-01

    The problems of vertically-integrated aquaculture are outlined; they are concerned with: species limitations (in the market, biological and technological); site selection, feed, manpower needs, and legal, institutional and financial requirements. The gaps in understanding of, and the constraints limiting, large-scale aquaculture are listed. Future action is recommended with respect to: types and diversity of species to be cultivated, marketing, biotechnology (seed supply, disease control, water quality and concerted effort), siting, feed, manpower, legal and institutional aids (granting of water rights, grants, tax breaks, duty-free imports, etc.), and adequate financing. The last of hard data based on experience suggests that large-scale vertically-integrated aquaculture is a high risk enterprise, and with the high capital investment required, banks and funding institutions are wary of supporting it. Investment in pilot projects is suggested to demonstrate that large-scale aquaculture can be a fully functional and successful business. Construction and operation of such pilot farms is judged to be in the interests of both the public and private sector.

  10. Large-scale fracture mechancis testing -- requirements and possibilities

    International Nuclear Information System (INIS)

    Brumovsky, M.

    1993-01-01

    Application of fracture mechanics to very important and/or complicated structures, like reactor pressure vessels, brings also some questions about the reliability and precision of such calculations. These problems become more pronounced in cases of elastic-plastic conditions of loading and/or in parts with non-homogeneous materials (base metal and austenitic cladding, property gradient changes through material thickness) or with non-homogeneous stress fields (nozzles, bolt threads, residual stresses etc.). For such special cases some verification by large-scale testing is necessary and valuable. This paper discusses problems connected with planning of such experiments with respect to their limitations, requirements to a good transfer of received results to an actual vessel. At the same time, an analysis of possibilities of small-scale model experiments is also shown, mostly in connection with application of results between standard, small-scale and large-scale experiments. Experience from 30 years of large-scale testing in SKODA is used as an example to support this analysis. 1 fig

  11. BILGO: Bilateral greedy optimization for large scale semidefinite programming

    KAUST Repository

    Hao, Zhifeng; Yuan, Ganzhao; Ghanem, Bernard

    2013-01-01

    Many machine learning tasks (e.g. metric and manifold learning problems) can be formulated as convex semidefinite programs. To enable the application of these tasks on a large-scale, scalability and computational efficiency are considered as desirable properties for a practical semidefinite programming algorithm. In this paper, we theoretically analyze a new bilateral greedy optimization (denoted BILGO) strategy in solving general semidefinite programs on large-scale datasets. As compared to existing methods, BILGO employs a bilateral search strategy during each optimization iteration. In such an iteration, the current semidefinite matrix solution is updated as a bilateral linear combination of the previous solution and a suitable rank-1 matrix, which can be efficiently computed from the leading eigenvector of the descent direction at this iteration. By optimizing for the coefficients of the bilateral combination, BILGO reduces the cost function in every iteration until the KKT conditions are fully satisfied, thus, it tends to converge to a global optimum. In fact, we prove that BILGO converges to the global optimal solution at a rate of O(1/k), where k is the iteration counter. The algorithm thus successfully combines the efficiency of conventional rank-1 update algorithms and the effectiveness of gradient descent. Moreover, BILGO can be easily extended to handle low rank constraints. To validate the effectiveness and efficiency of BILGO, we apply it to two important machine learning tasks, namely Mahalanobis metric learning and maximum variance unfolding. Extensive experimental results clearly demonstrate that BILGO can solve large-scale semidefinite programs efficiently.

  12. Utilization of Large Scale Surface Models for Detailed Visibility Analyses

    Science.gov (United States)

    Caha, J.; Kačmařík, M.

    2017-11-01

    This article demonstrates utilization of large scale surface models with small spatial resolution and high accuracy, acquired from Unmanned Aerial Vehicle scanning, for visibility analyses. The importance of large scale data for visibility analyses on the local scale, where the detail of the surface model is the most defining factor, is described. The focus is not only the classic Boolean visibility, that is usually determined within GIS, but also on so called extended viewsheds that aims to provide more information about visibility. The case study with examples of visibility analyses was performed on river Opava, near the Ostrava city (Czech Republic). The multiple Boolean viewshed analysis and global horizon viewshed were calculated to determine most prominent features and visibility barriers of the surface. Besides that, the extended viewshed showing angle difference above the local horizon, which describes angular height of the target area above the barrier, is shown. The case study proved that large scale models are appropriate data source for visibility analyses on local level. The discussion summarizes possible future applications and further development directions of visibility analyses.

  13. Photorealistic large-scale urban city model reconstruction.

    Science.gov (United States)

    Poullis, Charalambos; You, Suya

    2009-01-01

    The rapid and efficient creation of virtual environments has become a crucial part of virtual reality applications. In particular, civil and defense applications often require and employ detailed models of operations areas for training, simulations of different scenarios, planning for natural or man-made events, monitoring, surveillance, games, and films. A realistic representation of the large-scale environments is therefore imperative for the success of such applications since it increases the immersive experience of its users and helps reduce the difference between physical and virtual reality. However, the task of creating such large-scale virtual environments still remains a time-consuming and manual work. In this work, we propose a novel method for the rapid reconstruction of photorealistic large-scale virtual environments. First, a novel, extendible, parameterized geometric primitive is presented for the automatic building identification and reconstruction of building structures. In addition, buildings with complex roofs containing complex linear and nonlinear surfaces are reconstructed interactively using a linear polygonal and a nonlinear primitive, respectively. Second, we present a rendering pipeline for the composition of photorealistic textures, which unlike existing techniques, can recover missing or occluded texture information by integrating multiple information captured from different optical sensors (ground, aerial, and satellite).

  14. Image-based Exploration of Large-Scale Pathline Fields

    KAUST Repository

    Nagoor, Omniah H.

    2014-05-27

    While real-time applications are nowadays routinely used in visualizing large nu- merical simulations and volumes, handling these large-scale datasets requires high-end graphics clusters or supercomputers to process and visualize them. However, not all users have access to powerful clusters. Therefore, it is challenging to come up with a visualization approach that provides insight to large-scale datasets on a single com- puter. Explorable images (EI) is one of the methods that allows users to handle large data on a single workstation. Although it is a view-dependent method, it combines both exploration and modification of visual aspects without re-accessing the original huge data. In this thesis, we propose a novel image-based method that applies the concept of EI in visualizing large flow-field pathlines data. The goal of our work is to provide an optimized image-based method, which scales well with the dataset size. Our approach is based on constructing a per-pixel linked list data structure in which each pixel contains a list of pathlines segments. With this view-dependent method it is possible to filter, color-code and explore large-scale flow data in real-time. In addition, optimization techniques such as early-ray termination and deferred shading are applied, which further improves the performance and scalability of our approach.

  15. [A large-scale accident in Alpine terrain].

    Science.gov (United States)

    Wildner, M; Paal, P

    2015-02-01

    Due to the geographical conditions, large-scale accidents amounting to mass casualty incidents (MCI) in Alpine terrain regularly present rescue teams with huge challenges. Using an example incident, specific conditions and typical problems associated with such a situation are presented. The first rescue team members to arrive have the elementary tasks of qualified triage and communication to the control room, which is required to dispatch the necessary additional support. Only with a clear "concept", to which all have to adhere, can the subsequent chaos phase be limited. In this respect, a time factor confounded by adverse weather conditions or darkness represents enormous pressure. Additional hazards are frostbite and hypothermia. If priorities can be established in terms of urgency, then treatment and procedure algorithms have proven successful. For evacuation of causalities, a helicopter should be strived for. Due to the low density of hospitals in Alpine regions, it is often necessary to distribute the patients over a wide area. Rescue operations in Alpine terrain have to be performed according to the particular conditions and require rescue teams to have specific knowledge and expertise. The possibility of a large-scale accident should be considered when planning events. With respect to optimization of rescue measures, regular training and exercises are rational, as is the analysis of previous large-scale Alpine accidents.

  16. Robust large-scale parallel nonlinear solvers for simulations.

    Energy Technology Data Exchange (ETDEWEB)

    Bader, Brett William; Pawlowski, Roger Patrick; Kolda, Tamara Gibson (Sandia National Laboratories, Livermore, CA)

    2005-11-01

    This report documents research to develop robust and efficient solution techniques for solving large-scale systems of nonlinear equations. The most widely used method for solving systems of nonlinear equations is Newton's method. While much research has been devoted to augmenting Newton-based solvers (usually with globalization techniques), little has been devoted to exploring the application of different models. Our research has been directed at evaluating techniques using different models than Newton's method: a lower order model, Broyden's method, and a higher order model, the tensor method. We have developed large-scale versions of each of these models and have demonstrated their use in important applications at Sandia. Broyden's method replaces the Jacobian with an approximation, allowing codes that cannot evaluate a Jacobian or have an inaccurate Jacobian to converge to a solution. Limited-memory methods, which have been successful in optimization, allow us to extend this approach to large-scale problems. We compare the robustness and efficiency of Newton's method, modified Newton's method, Jacobian-free Newton-Krylov method, and our limited-memory Broyden method. Comparisons are carried out for large-scale applications of fluid flow simulations and electronic circuit simulations. Results show that, in cases where the Jacobian was inaccurate or could not be computed, Broyden's method converged in some cases where Newton's method failed to converge. We identify conditions where Broyden's method can be more efficient than Newton's method. We also present modifications to a large-scale tensor method, originally proposed by Bouaricha, for greater efficiency, better robustness, and wider applicability. Tensor methods are an alternative to Newton-based methods and are based on computing a step based on a local quadratic model rather than a linear model. The advantage of Bouaricha's method is that it can use any

  17. Foundational perspectives on causality in large-scale brain networks

    Science.gov (United States)

    Mannino, Michael; Bressler, Steven L.

    2015-12-01

    A profusion of recent work in cognitive neuroscience has been concerned with the endeavor to uncover causal influences in large-scale brain networks. However, despite the fact that many papers give a nod to the important theoretical challenges posed by the concept of causality, this explosion of research has generally not been accompanied by a rigorous conceptual analysis of the nature of causality in the brain. This review provides both a descriptive and prescriptive account of the nature of causality as found within and between large-scale brain networks. In short, it seeks to clarify the concept of causality in large-scale brain networks both philosophically and scientifically. This is accomplished by briefly reviewing the rich philosophical history of work on causality, especially focusing on contributions by David Hume, Immanuel Kant, Bertrand Russell, and Christopher Hitchcock. We go on to discuss the impact that various interpretations of modern physics have had on our understanding of causality. Throughout all this, a central focus is the distinction between theories of deterministic causality (DC), whereby causes uniquely determine their effects, and probabilistic causality (PC), whereby causes change the probability of occurrence of their effects. We argue that, given the topological complexity of its large-scale connectivity, the brain should be considered as a complex system and its causal influences treated as probabilistic in nature. We conclude that PC is well suited for explaining causality in the brain for three reasons: (1) brain causality is often mutual; (2) connectional convergence dictates that only rarely is the activity of one neuronal population uniquely determined by another one; and (3) the causal influences exerted between neuronal populations may not have observable effects. A number of different techniques are currently available to characterize causal influence in the brain. Typically, these techniques quantify the statistical

  18. Large scale circulation patterns associated to seasonal dry and wet conditions over the Czech Republic

    OpenAIRE

    Boroneant, Constanta; Potop, Vera; Mozny, Martin; Stepanek, Petr; Skalak, Petr

    2012-01-01

    Ponencia presentada en: VIII Congreso de la Asociación Española de Climatología celebrado en Salamanca entre el 25 y el 28 de septiembre de 2012. [ES]Este trabajo analiza la relación entre las condiciones estaciónales extremadamente secas y húmedas en la República Checa y los patrones de circulación de gran escala. El índice estandarizado de precipitación y evapotranspiración (SPEI) se utiliza para cuantificar las condiciones de humedad. El SPEI fue calculado a partir de los regis...

  19. Atmospheric HT and HTO: V. distribution and large-scale circulation

    International Nuclear Information System (INIS)

    Mason, A.S.; Oestlund, H.G.

    1979-01-01

    The two major chemical forms of atmospheric tritium are water vapour (HTO) and hydrogen gas (HT). These forms have quite different sources, distributions and sinks. The chemical conversion from HT to HTO in the atmosphere proceeds with a characteristic time of 6.5 years. Combined with the radioactive decay, a net lifetime of 4.8 years is estimated for atmospheric HT. HT is released predominately at the surface in mid- to high latitudes in the northern hemisphere. A negative gradient southward has been found from aircraft transects and from sampling at surface stations. After many years of a relatively constant global inventory of 1.1 kg of tritium gas, the HT mixing ratios decreased during 1977, with the sharpest drop at high latitudes. The estimated decline in annual production was 100 g. At the end of 1977, the atmospheric HT burden was 1.0 kg, and the estimated annual release was 200 g. An unknown portion is present as T 2 gas. The effect of T 2 is to decrease the net lifetime to 3.7 years. In the troposphere, the cycle of HTO has been treated exhaustively by others. The stratospheric distribution of HTO has been sampled from aircraft, and found to increase rapidly with height above the troposphere. An annual cycle has been observed, in which the lower stratosphere is depleted during the spring, and replenished by subsidence from higher levels during summer and fall. The effects of a nuclear test by the People's Republic of China in November 1976 have been clearly observed in the stratospheric HTO; however, no HT deposition was found. Presumably, the HTO at higher levels was originally deposited by the large nuclear weapons tests of the 1960s. An estimated 5 kg of tritium are now present in the stratosphere below 19 km. (author)

  20. The Nature of Global Large-scale Sea Level Variability in Relation to Atmospheric Forcing: A Modeling Study

    Science.gov (United States)

    Fukumori, I.; Raghunath, R.; Fu, L. L.

    1996-01-01

    The relation between large-scale sea level variability and ocean circulation is studied using a numerical model. A global primitive equaiton model of the ocean is forced by daily winds and climatological heat fluxes corresponding to the period from January 1992 to February 1996. The physical nature of the temporal variability from periods of days to a year, are examined based on spectral analyses of model results and comparisons with satellite altimetry and tide gauge measurements.

  1. Potential climatic impacts and reliability of large-scale offshore wind farms

    International Nuclear Information System (INIS)

    Wang Chien; Prinn, Ronald G

    2011-01-01

    The vast availability of wind power has fueled substantial interest in this renewable energy source as a potential near-zero greenhouse gas emission technology for meeting future world energy needs while addressing the climate change issue. However, in order to provide even a fraction of the estimated future energy needs, a large-scale deployment of wind turbines (several million) is required. The consequent environmental impacts, and the inherent reliability of such a large-scale usage of intermittent wind power would have to be carefully assessed, in addition to the need to lower the high current unit wind power costs. Our previous study (Wang and Prinn 2010 Atmos. Chem. Phys. 10 2053) using a three-dimensional climate model suggested that a large deployment of wind turbines over land to meet about 10% of predicted world energy needs in 2100 could lead to a significant temperature increase in the lower atmosphere over the installed regions. A global-scale perturbation to the general circulation patterns as well as to the cloud and precipitation distribution was also predicted. In the later study reported here, we conducted a set of six additional model simulations using an improved climate model to further address the potential environmental and intermittency issues of large-scale deployment of offshore wind turbines for differing installation areas and spatial densities. In contrast to the previous land installation results, the offshore wind turbine installations are found to cause a surface cooling over the installed offshore regions. This cooling is due principally to the enhanced latent heat flux from the sea surface to lower atmosphere, driven by an increase in turbulent mixing caused by the wind turbines which was not entirely offset by the concurrent reduction of mean wind kinetic energy. We found that the perturbation of the large-scale deployment of offshore wind turbines to the global climate is relatively small compared to the case of land

  2. Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

  3. Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

    Directory of Open Access Journals (Sweden)

    Luis Carlos Pinto de Macedo-Soares

    Full Text Available Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

  4. Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

    Science.gov (United States)

    de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

    2014-01-01

    Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

  5. Diagnosing indicators of large-scale forcing of east-coast cyclogenesis

    International Nuclear Information System (INIS)

    Dowdy, Andrew J; Mills, Graham A; Timbal, Bertrand

    2010-01-01

    Extra-tropical cyclones that develop near the east coast of Australia often have severe consequences such as flash flooding and damaging winds and seas, as well as beneficial consequences such as being responsible for heavy rainfall events that contribute significantly to total rainfall and runoff. There is subjective evidence that the development of most major events, commonly known as East Coast Lows, is associated with the movement of a high amplitude upper-tropospheric trough system over eastern Australia. This paper examines a number of upper-tropospheric diagnostic quantities that might provide a basis for preparing a climatology of the large-scale drivers of east-coast cyclogenesis. A preliminary climatology of these diagnostic quantities, based on ECMWF interim reanalyses, is compared with a database of observed East Coast Low events. The potential application of these diagnostics to global climate model simulations of past and future climates is also discussed.

  6. African aerosol and large-scale precipitation variability over West Africa

    International Nuclear Information System (INIS)

    Huang Jingfeng; Zhang Chidong; Prospero, Joseph M

    2009-01-01

    We investigated the large-scale connection between African aerosol and precipitation in the West African Monsoon (WAM) region using 8-year (2000-2007) monthly and daily Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products (aerosol optical depth, fine mode fraction) and Tropical Rainfall Measuring Mission (TRMM) precipitation and rain type. These high-quality data further confirmed our previous results that the large-scale link between aerosol and precipitation in this region undergoes distinct seasonal and spatial variability. Previously detected suppression of precipitation during months of high aerosol concentration occurs in both convective and stratiform rain, but not systematically in shallow rain. This suggests the suppression of deep convection due to the aerosol. Based on the seasonal cycle of dust and smoke and their geographical distribution, our data suggest that both dust (coarse mode aerosol) and smoke (fine mode aerosol) contribute to the precipitation suppression. However, the dust effect is evident over the Gulf of Guinea while the smoke effect is evident over both land and ocean. A back trajectory analysis further demonstrates that the precipitation reduction is statistically linked to the upwind aerosol concentration. This study suggests that African aerosol outbreaks in the WAM region can influence precipitation in the local monsoon system which has direct societal impact on the local community. It calls for more systematic investigations to determine the modulating mechanisms using both observational and modeling approaches.

  7. Impact of air-sea drag coefficient for latent heat flux on large scale climate in coupled and atmosphere stand-alone simulations

    Science.gov (United States)

    Torres, Olivier; Braconnot, Pascale; Marti, Olivier; Gential, Luc

    2018-05-01

    The turbulent fluxes across the ocean/atmosphere interface represent one of the principal driving forces of the global atmospheric and oceanic circulation. Despite decades of effort and improvements, representation of these fluxes still presents a challenge due to the small-scale acting turbulent processes compared to the resolved scales of the models. Beyond this subgrid parameterization issue, a comprehensive understanding of the impact of air-sea interactions on the climate system is still lacking. In this paper we investigates the large-scale impacts of the transfer coefficient used to compute turbulent heat fluxes with the IPSL-CM4 climate model in which the surface bulk formula is modified. Analyzing both atmosphere and coupled ocean-atmosphere general circulation model (AGCM, OAGCM) simulations allows us to study the direct effect and the mechanisms of adjustment to this modification. We focus on the representation of latent heat flux in the tropics. We show that the heat transfer coefficients are highly similar for a given parameterization between AGCM and OAGCM simulations. Although the same areas are impacted in both kind of simulations, the differences in surface heat fluxes are substantial. A regional modification of heat transfer coefficient has more impact than uniform modification in AGCM simulations while in OAGCM simulations, the opposite is observed. By studying the global energetics and the atmospheric circulation response to the modification, we highlight the role of the ocean in dampening a large part of the disturbance. Modification of the heat exchange coefficient modifies the way the coupled system works due to the link between atmospheric circulation and SST, and the different feedbacks between ocean and atmosphere. The adjustment that takes place implies a balance of net incoming solar radiation that is the same in all simulations. As there is no change in model physics other than drag coefficient, we obtain similar latent heat flux

  8. Large-scale compositional heterogeneity in the Earth's mantle

    Science.gov (United States)

    Ballmer, M.

    2017-12-01

    Seismic imaging of subducted Farallon and Tethys lithosphere in the lower mantle has been taken as evidence for whole-mantle convection, and efficient mantle mixing. However, cosmochemical constraints point to a lower-mantle composition that has a lower Mg/Si compared to upper-mantle pyrolite. Moreover, geochemical signatures of magmatic rocks indicate the long-term persistence of primordial reservoirs somewhere in the mantle. In this presentation, I establish geodynamic mechanisms for sustaining large-scale (primordial) heterogeneity in the Earth's mantle using numerical models. Mantle flow is controlled by rock density and viscosity. Variations in intrinsic rock density, such as due to heterogeneity in basalt or iron content, can induce layering or partial layering in the mantle. Layering can be sustained in the presence of persistent whole mantle convection due to active "unmixing" of heterogeneity in low-viscosity domains, e.g. in the transition zone or near the core-mantle boundary [1]. On the other hand, lateral variations in intrinsic rock viscosity, such as due to heterogeneity in Mg/Si, can strongly affect the mixing timescales of the mantle. In the extreme case, intrinsically strong rocks may remain unmixed through the age of the Earth, and persist as large-scale domains in the mid-mantle due to focusing of deformation along weak conveyor belts [2]. That large-scale lateral heterogeneity and/or layering can persist in the presence of whole-mantle convection can explain the stagnation of some slabs, as well as the deflection of some plumes, in the mid-mantle. These findings indeed motivate new seismic studies for rigorous testing of model predictions. [1] Ballmer, M. D., N. C. Schmerr, T. Nakagawa, and J. Ritsema (2015), Science Advances, doi:10.1126/sciadv.1500815. [2] Ballmer, M. D., C. Houser, J. W. Hernlund, R. Wentzcovitch, and K. Hirose (2017), Nature Geoscience, doi:10.1038/ngeo2898.

  9. On the Phenomenology of an Accelerated Large-Scale Universe

    Directory of Open Access Journals (Sweden)

    Martiros Khurshudyan

    2016-10-01

    Full Text Available In this review paper, several new results towards the explanation of the accelerated expansion of the large-scale universe is discussed. On the other hand, inflation is the early-time accelerated era and the universe is symmetric in the sense of accelerated expansion. The accelerated expansion of is one of the long standing problems in modern cosmology, and physics in general. There are several well defined approaches to solve this problem. One of them is an assumption concerning the existence of dark energy in recent universe. It is believed that dark energy is responsible for antigravity, while dark matter has gravitational nature and is responsible, in general, for structure formation. A different approach is an appropriate modification of general relativity including, for instance, f ( R and f ( T theories of gravity. On the other hand, attempts to build theories of quantum gravity and assumptions about existence of extra dimensions, possible variability of the gravitational constant and the speed of the light (among others, provide interesting modifications of general relativity applicable to problems of modern cosmology, too. In particular, here two groups of cosmological models are discussed. In the first group the problem of the accelerated expansion of large-scale universe is discussed involving a new idea, named the varying ghost dark energy. On the other hand, the second group contains cosmological models addressed to the same problem involving either new parameterizations of the equation of state parameter of dark energy (like varying polytropic gas, or nonlinear interactions between dark energy and dark matter. Moreover, for cosmological models involving varying ghost dark energy, massless particle creation in appropriate radiation dominated universe (when the background dynamics is due to general relativity is demonstrated as well. Exploring the nature of the accelerated expansion of the large-scale universe involving generalized

  10. Solving large scale structure in ten easy steps with COLA

    Energy Technology Data Exchange (ETDEWEB)

    Tassev, Svetlin [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States); Zaldarriaga, Matias [School of Natural Sciences, Institute for Advanced Study, Olden Lane, Princeton, NJ 08540 (United States); Eisenstein, Daniel J., E-mail: stassev@cfa.harvard.edu, E-mail: matiasz@ias.edu, E-mail: deisenstein@cfa.harvard.edu [Center for Astrophysics, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-06-01

    We present the COmoving Lagrangian Acceleration (COLA) method: an N-body method for solving for Large Scale Structure (LSS) in a frame that is comoving with observers following trajectories calculated in Lagrangian Perturbation Theory (LPT). Unlike standard N-body methods, the COLA method can straightforwardly trade accuracy at small-scales in order to gain computational speed without sacrificing accuracy at large scales. This is especially useful for cheaply generating large ensembles of accurate mock halo catalogs required to study galaxy clustering and weak lensing, as those catalogs are essential for performing detailed error analysis for ongoing and future surveys of LSS. As an illustration, we ran a COLA-based N-body code on a box of size 100 Mpc/h with particles of mass ≈ 5 × 10{sup 9}M{sub s}un/h. Running the code with only 10 timesteps was sufficient to obtain an accurate description of halo statistics down to halo masses of at least 10{sup 11}M{sub s}un/h. This is only at a modest speed penalty when compared to mocks obtained with LPT. A standard detailed N-body run is orders of magnitude slower than our COLA-based code. The speed-up we obtain with COLA is due to the fact that we calculate the large-scale dynamics exactly using LPT, while letting the N-body code solve for the small scales, without requiring it to capture exactly the internal dynamics of halos. Achieving a similar level of accuracy in halo statistics without the COLA method requires at least 3 times more timesteps than when COLA is employed.

  11. Nonlinear evolution of large-scale structure in the universe

    International Nuclear Information System (INIS)

    Frenk, C.S.; White, S.D.M.; Davis, M.

    1983-01-01

    Using N-body simulations we study the nonlinear development of primordial density perturbation in an Einstein--de Sitter universe. We compare the evolution of an initial distribution without small-scale density fluctuations to evolution from a random Poisson distribution. These initial conditions mimic the assumptions of the adiabatic and isothermal theories of galaxy formation. The large-scale structures which form in the two cases are markedly dissimilar. In particular, the correlation function xi(r) and the visual appearance of our adiabatic (or ''pancake'') models match better the observed distribution of galaxies. This distribution is characterized by large-scale filamentary structure. Because the pancake models do not evolve in a self-similar fashion, the slope of xi(r) steepens with time; as a result there is a unique epoch at which these models fit the galaxy observations. We find the ratio of cutoff length to correlation length at this time to be lambda/sub min//r 0 = 5.1; its expected value in a neutrino dominated universe is 4(Ωh) -1 (H 0 = 100h km s -1 Mpc -1 ). At early epochs these models predict a negligible amplitude for xi(r) and could explain the lack of measurable clustering in the Lyα absorption lines of high-redshift quasars. However, large-scale structure in our models collapses after z = 2. If this collapse precedes galaxy formation as in the usual pancake theory, galaxies formed uncomfortably recently. The extent of this problem may depend on the cosmological model used; the present series of experiments should be extended in the future to include models with Ω<1

  12. Recent Advances in Understanding Large Scale Vapour Explosions

    International Nuclear Information System (INIS)

    Board, S.J.; Hall, R.W.

    1976-01-01

    In foundries, violent explosions occur occasionally when molten metal comes into contact with water. If similar explosions can occur with other materials, hazardous situations may arise for example in LNG marine transportation accidents, or in liquid cooled reactor incidents when molten UO 2 contacts water or sodium coolant. Over the last 10 years a large body of experimental data has been obtained on the behaviour of small quantities of hot material in contact with a vaporisable coolant. Such experiments generally give low energy yields, despite producing fine fragmentation of the molten material. These events have been interpreted in terms of a wide range of phenomena such as violent boiling, liquid entrainment, bubble collapse, superheat, surface cracking and many others. Many of these studies have been aimed at understanding the small scale behaviour of the particular materials of interest. However, understanding the nature of the energetic events which were the original cause for concern may also be necessary to give confidence that violent events cannot occur for these materials in large scale situations. More recently, there has been a trend towards larger experiments and some of these have produced explosions of moderately high efficiency. Although occurrence of such large scale explosions can depend rather critically on initial conditions in a way which is not fully understood, there are signs that the interpretation of these events may be more straightforward than that of the single drop experiments. In the last two years several theoretical models for large scale explosions have appeared which attempt a self contained explanation of at least some stages of such high yield events: these have as their common feature a description of how a propagating breakdown of an initially quasi-stable distribution of materials is induced by the pressure and flow field caused by the energy release in adjacent regions. These models have led to the idea that for a full

  13. Generation Expansion Planning Considering Integrating Large-scale Wind Generation

    DEFF Research Database (Denmark)

    Zhang, Chunyu; Ding, Yi; Østergaard, Jacob

    2013-01-01

    necessitated the inclusion of more innovative and sophisticated approaches in power system investment planning. A bi-level generation expansion planning approach considering large-scale wind generation was proposed in this paper. The first phase is investment decision, while the second phase is production...... optimization decision. A multi-objective PSO (MOPSO) algorithm was introduced to solve this optimization problem, which can accelerate the convergence and guarantee the diversity of Pareto-optimal front set as well. The feasibility and effectiveness of the proposed bi-level planning approach and the MOPSO...

  14. Safeguarding aspects of large-scale commercial reprocessing plants

    International Nuclear Information System (INIS)

    1979-03-01

    The paper points out that several solutions to the problems of safeguarding large-scale plants have been put forward: (1) Increased measurement accuracy. This does not remove the problem of timely detection. (2) Continuous in-process measurement. As yet unproven and likely to be costly. (3) More extensive use of containment and surveillance. The latter appears to be feasible but requires the incorporation of safeguards into plant design and sufficient redundancy to protect the operators interests. The advantages of altering the emphasis of safeguards philosophy from quantitative goals to the analysis of diversion strategies should be considered

  15. Large-Scale Graph Processing Using Apache Giraph

    KAUST Repository

    Sakr, Sherif

    2017-01-07

    This book takes its reader on a journey through Apache Giraph, a popular distributed graph processing platform designed to bring the power of big data processing to graph data. Designed as a step-by-step self-study guide for everyone interested in large-scale graph processing, it describes the fundamental abstractions of the system, its programming models and various techniques for using the system to process graph data at scale, including the implementation of several popular and advanced graph analytics algorithms.

  16. Highly Scalable Trip Grouping for Large Scale Collective Transportation Systems

    DEFF Research Database (Denmark)

    Gidofalvi, Gyozo; Pedersen, Torben Bach; Risch, Tore

    2008-01-01

    Transportation-related problems, like road congestion, parking, and pollution, are increasing in most cities. In order to reduce traffic, recent work has proposed methods for vehicle sharing, for example for sharing cabs by grouping "closeby" cab requests and thus minimizing transportation cost...... and utilizing cab space. However, the methods published so far do not scale to large data volumes, which is necessary to facilitate large-scale collective transportation systems, e.g., ride-sharing systems for large cities. This paper presents highly scalable trip grouping algorithms, which generalize previous...

  17. Large-scale computing techniques for complex system simulations

    CERN Document Server

    Dubitzky, Werner; Schott, Bernard

    2012-01-01

    Complex systems modeling and simulation approaches are being adopted in a growing number of sectors, including finance, economics, biology, astronomy, and many more. Technologies ranging from distributed computing to specialized hardware are explored and developed to address the computational requirements arising in complex systems simulations. The aim of this book is to present a representative overview of contemporary large-scale computing technologies in the context of complex systems simulations applications. The intention is to identify new research directions in this field and

  18. Large-Scale Analysis of Network Bistability for Human Cancers

    Science.gov (United States)

    Shiraishi, Tetsuya; Matsuyama, Shinako; Kitano, Hiroaki

    2010-01-01

    Protein–protein interaction and gene regulatory networks are likely to be locked in a state corresponding to a disease by the behavior of one or more bistable circuits exhibiting switch-like behavior. Sets of genes could be over-expressed or repressed when anomalies due to disease appear, and the circuits responsible for this over- or under-expression might persist for as long as the disease state continues. This paper shows how a large-scale analysis of network bistability for various human cancers can identify genes that can potentially serve as drug targets or diagnosis biomarkers. PMID:20628618

  19. Development of Large-Scale Spacecraft Fire Safety Experiments

    DEFF Research Database (Denmark)

    Ruff, Gary A.; Urban, David L.; Fernandez-Pello, A. Carlos

    2013-01-01

    exploration missions outside of low-earth orbit and accordingly, more complex in terms of operations, logistics, and safety. This will increase the challenge of ensuring a fire-safe environment for the crew throughout the mission. Based on our fundamental uncertainty of the behavior of fires in low...... of the spacecraft fire safety risk. The activity of this project is supported by an international topical team of fire experts from other space agencies who conduct research that is integrated into the overall experiment design. The large-scale space flight experiment will be conducted in an Orbital Sciences...

  20. Large scale obscuration and related climate effects open literature bibliography

    International Nuclear Information System (INIS)

    Russell, N.A.; Geitgey, J.; Behl, Y.K.; Zak, B.D.

    1994-05-01

    Large scale obscuration and related climate effects of nuclear detonations first became a matter of concern in connection with the so-called ''Nuclear Winter Controversy'' in the early 1980's. Since then, the world has changed. Nevertheless, concern remains about the atmospheric effects of nuclear detonations, but the source of concern has shifted. Now it focuses less on global, and more on regional effects and their resulting impacts on the performance of electro-optical and other defense-related systems. This bibliography reflects the modified interest

  1. Large Scale Composite Manufacturing for Heavy Lift Launch Vehicles

    Science.gov (United States)

    Stavana, Jacob; Cohen, Leslie J.; Houseal, Keth; Pelham, Larry; Lort, Richard; Zimmerman, Thomas; Sutter, James; Western, Mike; Harper, Robert; Stuart, Michael

    2012-01-01

    Risk reduction for the large scale composite manufacturing is an important goal to produce light weight components for heavy lift launch vehicles. NASA and an industry team successfully employed a building block approach using low-cost Automated Tape Layup (ATL) of autoclave and Out-of-Autoclave (OoA) prepregs. Several large, curved sandwich panels were fabricated at HITCO Carbon Composites. The aluminum honeycomb core sandwich panels are segments of a 1/16th arc from a 10 meter cylindrical barrel. Lessons learned highlight the manufacturing challenges required to produce light weight composite structures such as fairings for heavy lift launch vehicles.

  2. Large Scale Simulations of the Euler Equations on GPU Clusters

    KAUST Repository

    Liebmann, Manfred

    2010-08-01

    The paper investigates the scalability of a parallel Euler solver, using the Vijayasundaram method, on a GPU cluster with 32 Nvidia Geforce GTX 295 boards. The aim of this research is to enable large scale fluid dynamics simulations with up to one billion elements. We investigate communication protocols for the GPU cluster to compensate for the slow Gigabit Ethernet network between the GPU compute nodes and to maintain overall efficiency. A diesel engine intake-port and a nozzle, meshed in different resolutions, give good real world examples for the scalability tests on the GPU cluster. © 2010 IEEE.

  3. Enabling Large-Scale Biomedical Analysis in the Cloud

    Directory of Open Access Journals (Sweden)

    Ying-Chih Lin

    2013-01-01

    Full Text Available Recent progress in high-throughput instrumentations has led to an astonishing growth in both volume and complexity of biomedical data collected from various sources. The planet-size data brings serious challenges to the storage and computing technologies. Cloud computing is an alternative to crack the nut because it gives concurrent consideration to enable storage and high-performance computing on large-scale data. This work briefly introduces the data intensive computing system and summarizes existing cloud-based resources in bioinformatics. These developments and applications would facilitate biomedical research to make the vast amount of diversification data meaningful and usable.

  4. Large-scale structure in the universe: Theory vs observations

    International Nuclear Information System (INIS)

    Kashlinsky, A.; Jones, B.J.T.

    1990-01-01

    A variety of observations constrain models of the origin of large scale cosmic structures. We review here the elements of current theories and comment in detail on which of the current observational data provide the principal constraints. We point out that enough observational data have accumulated to constrain (and perhaps determine) the power spectrum of primordial density fluctuations over a very large range of scales. We discuss the theories in the light of observational data and focus on the potential of future observations in providing even (and ever) tighter constraints. (orig.)

  5. Current status of large-scale cryogenic gravitational wave telescope

    International Nuclear Information System (INIS)

    Kuroda, K; Ohashi, M; Miyoki, S; Uchiyama, T; Ishitsuka, H; Yamamoto, K; Kasahara, K; Fujimoto, M-K; Kawamura, S; Takahashi, R; Yamazaki, T; Arai, K; Tatsumi, D; Ueda, A; Fukushima, M; Sato, S; Nagano, S; Tsunesada, Y; Zhu, Zong-Hong; Shintomi, T; Yamamoto, A; Suzuki, T; Saito, Y; Haruyama, T; Sato, N; Higashi, Y; Tomaru, T; Tsubono, K; Ando, M; Takamori, A; Numata, K; Aso, Y; Ueda, K-I; Yoneda, H; Nakagawa, K; Musha, M; Mio, N; Moriwaki, S; Somiya, K; Araya, A; Kanda, N; Telada, S; Tagoshi, H; Nakamura, T; Sasaki, M; Tanaka, T; Oohara, K; Takahashi, H; Miyakawa, O; Tobar, M E

    2003-01-01

    The large-scale cryogenic gravitational wave telescope (LCGT) project is the proposed advancement of TAMA, which will be able to detect the coalescences of binary neutron stars occurring in our galaxy. LCGT intends to detect the coalescence events within about 240 Mpc, the rate of which is expected to be from 0.1 to several events in a year. LCGT has Fabry-Perot cavities of 3 km baseline and the mirrors are cooled down to a cryogenic temperature of 20 K. It is planned to be built in the underground of Kamioka mine. This paper overviews the revision of the design and the current status of the R and D

  6. Large scale obscuration and related climate effects open literature bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Russell, N.A.; Geitgey, J.; Behl, Y.K.; Zak, B.D.

    1994-05-01

    Large scale obscuration and related climate effects of nuclear detonations first became a matter of concern in connection with the so-called ``Nuclear Winter Controversy`` in the early 1980`s. Since then, the world has changed. Nevertheless, concern remains about the atmospheric effects of nuclear detonations, but the source of concern has shifted. Now it focuses less on global, and more on regional effects and their resulting impacts on the performance of electro-optical and other defense-related systems. This bibliography reflects the modified interest.

  7. Properties of large-scale methane/hydrogen jet fires

    Energy Technology Data Exchange (ETDEWEB)

    Studer, E. [CEA Saclay, DEN, LTMF Heat Transfer and Fluid Mech Lab, 91 - Gif-sur-Yvette (France); Jamois, D.; Leroy, G.; Hebrard, J. [INERIS, F-60150 Verneuil En Halatte (France); Jallais, S. [Air Liquide, F-78350 Jouy En Josas (France); Blanchetiere, V. [GDF SUEZ, 93 - La Plaine St Denis (France)

    2009-12-15

    A future economy based on reduction of carbon-based fuels for power generation and transportation may consider hydrogen as possible energy carrier Extensive and widespread use of hydrogen might require a pipeline network. The alternatives might be the use of the existing natural gas network or to design a dedicated network. Whatever the solution, mixing hydrogen with natural gas will modify the consequences of accidents, substantially The French National Research Agency (ANR) funded project called HYDROMEL focuses on these critical questions Within this project large-scale jet fires have been studied experimentally and numerically The main characteristics of these flames including visible length, radiation fluxes and blowout have been assessed. (authors)

  8. Less is more: regularization perspectives on large scale machine learning

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Deep learning based techniques provide a possible solution at the expanse of theoretical guidance and, especially, of computational requirements. It is then a key challenge for large scale machine learning to devise approaches guaranteed to be accurate and yet computationally efficient. In this talk, we will consider a regularization perspectives on machine learning appealing to classical ideas in linear algebra and inverse problems to scale-up dramatically nonparametric methods such as kernel methods, often dismissed because of prohibitive costs. Our analysis derives optimal theoretical guarantees while providing experimental results at par or out-performing state of the art approaches.

  9. Large-Scale Graph Processing Using Apache Giraph

    KAUST Repository

    Sakr, Sherif; Orakzai, Faisal Moeen; Abdelaziz, Ibrahim; Khayyat, Zuhair

    2017-01-01

    This book takes its reader on a journey through Apache Giraph, a popular distributed graph processing platform designed to bring the power of big data processing to graph data. Designed as a step-by-step self-study guide for everyone interested in large-scale graph processing, it describes the fundamental abstractions of the system, its programming models and various techniques for using the system to process graph data at scale, including the implementation of several popular and advanced graph analytics algorithms.

  10. Multidimensional quantum entanglement with large-scale integrated optics

    DEFF Research Database (Denmark)

    Wang, Jianwei; Paesani, Stefano; Ding, Yunhong

    2018-01-01

    -dimensional entanglement. A programmable bipartite entangled system is realized with dimension up to 15 × 15 on a large-scale silicon-photonics quantum circuit. The device integrates more than 550 photonic components on a single chip, including 16 identical photon-pair sources. We verify the high precision, generality......The ability to control multidimensional quantum systems is key for the investigation of fundamental science and for the development of advanced quantum technologies. We demonstrate a multidimensional integrated quantum photonic platform able to generate, control and analyze high...

  11. Status of large scale wind turbine technology development abroad?

    Institute of Scientific and Technical Information of China (English)

    Ye LI; Lei DUAN

    2016-01-01

    To facilitate the large scale (multi-megawatt) wind turbine development in China, the foreign e?orts and achievements in the area are reviewed and summarized. Not only the popular horizontal axis wind turbines on-land but also the o?shore wind turbines, vertical axis wind turbines, airborne wind turbines, and shroud wind turbines are discussed. The purpose of this review is to provide a comprehensive comment and assessment about the basic work principle, economic aspects, and environmental impacts of turbines.

  12. Cosmological parameters from large scale structure - geometric versus shape information

    CERN Document Server

    Hamann, Jan; Lesgourgues, Julien; Rampf, Cornelius; Wong, Yvonne Y Y

    2010-01-01

    The matter power spectrum as derived from large scale structure (LSS) surveys contains two important and distinct pieces of information: an overall smooth shape and the imprint of baryon acoustic oscillations (BAO). We investigate the separate impact of these two types of information on cosmological parameter estimation, and show that for the simplest cosmological models, the broad-band shape information currently contained in the SDSS DR7 halo power spectrum (HPS) is by far superseded by geometric information derived from the baryonic features. An immediate corollary is that contrary to popular beliefs, the upper limit on the neutrino mass m_\

  13. Test on large-scale seismic isolation elements, 2

    International Nuclear Information System (INIS)

    Mazda, T.; Moteki, M.; Ishida, K.; Shiojiri, H.; Fujita, T.

    1991-01-01

    Seismic isolation test program of Central Research Inst. of Electric Power Industry (CRIEPI) to apply seismic isolation to Fast Breeder Reactor (FBR) plant was started in 1987. In this test program, demonstration test of seismic isolation elements was considered as one of the most important research items. Facilities for testing seismic isolation elements were built in Abiko Research Laboratory of CRIEPI. Various tests of large-scale seismic isolation elements were conducted up to this day. Many important test data to develop design technical guidelines was obtained. (author)

  14. Large scale PV plants - also in Denmark. Project report

    Energy Technology Data Exchange (ETDEWEB)

    Ahm, P [PA Energy, Malling (Denmark); Vedde, J [SiCon. Silicon and PV consulting, Birkeroed (Denmark)

    2011-04-15

    Large scale PV (LPV) plants, plants with a capacity of more than 200 kW, has since 2007 constituted an increasing share of the global PV installations. In 2009 large scale PV plants with cumulative power more that 1,3 GWp were connected to the grid. The necessary design data for LPV plants in Denmark are available or can be found, although irradiance data could be improved. There seems to be very few institutional barriers for LPV projects, but as so far no real LPV projects have been processed, these findings have to be regarded as preliminary. The fast growing number of very large scale solar thermal plants for district heating applications supports these findings. It has further been investigated, how to optimize the lay-out of LPV plants. Under the Danish irradiance conditions with several winter months with very low solar height PV installations on flat surfaces will have to balance the requirements of physical space - and cost, and the loss of electricity production due to shadowing effects. The potential for LPV plants in Denmark are found in three main categories: PV installations on flat roof of large commercial buildings, PV installations on other large scale infrastructure such as noise barriers and ground mounted PV installations. The technical potential for all three categories is found to be significant and in the range of 50 - 250 km2. In terms of energy harvest PV plants will under Danish conditions exhibit an overall efficiency of about 10 % in conversion of the energy content of the light compared to about 0,3 % for biomass. The theoretical ground area needed to produce the present annual electricity consumption of Denmark at 33-35 TWh is about 300 km2 The Danish grid codes and the electricity safety regulations mention very little about PV and nothing about LPV plants. It is expected that LPV plants will be treated similarly to big wind turbines. A number of LPV plant scenarios have been investigated in detail based on real commercial offers and

  15. Testing Inflation with Large Scale Structure: Connecting Hopes with Reality

    International Nuclear Information System (INIS)

    Alvarez, Marcello; Baldauf, T.; Bond, J. Richard; Dalal, N.; Putter, R. D.; Dore, O.; Green, Daniel; Hirata, Chris; Huang, Zhiqi; Huterer, Dragan; Jeong, Donghui; Johnson, Matthew C.; Krause, Elisabeth; Loverde, Marilena; Meyers, Joel; Meeburg, Daniel; Senatore, Leonardo; Shandera, Sarah; Silverstein, Eva; Slosar, Anze; Smith, Kendrick; Zaldarriaga, Matias; Assassi, Valentin; Braden, Jonathan; Hajian, Amir; Kobayashi, Takeshi; Stein, George; Engelen, Alexander van

    2014-01-01

    The statistics of primordial curvature fluctuations are our window into the period of inflation, where these fluctuations were generated. To date, the cosmic microwave background has been the dominant source of information about these perturbations. Large-scale structure is, however, from where drastic improvements should originate. In this paper, we explain the theoretical motivations for pursuing such measurements and the challenges that lie ahead. In particular, we discuss and identify theoretical targets regarding the measurement of primordial non-Gaussianity. We argue that when quantified in terms of the local (equilateral) template amplitude floc\

  16. Design techniques for large scale linear measurement systems

    International Nuclear Information System (INIS)

    Candy, J.V.

    1979-03-01

    Techniques to design measurement schemes for systems modeled by large scale linear time invariant systems, i.e., physical systems modeled by a large number (> 5) of ordinary differential equations, are described. The techniques are based on transforming the physical system model to a coordinate system facilitating the design and then transforming back to the original coordinates. An example of a three-stage, four-species, extraction column used in the reprocessing of spent nuclear fuel elements is presented. The basic ideas are briefly discussed in the case of noisy measurements. An example using a plutonium nitrate storage vessel (reprocessing) with measurement uncertainty is also presented

  17. How Large-Scale Research Facilities Connect to Global Research

    DEFF Research Database (Denmark)

    Lauto, Giancarlo; Valentin, Finn

    2013-01-01

    Policies for large-scale research facilities (LSRFs) often highlight their spillovers to industrial innovation and their contribution to the external connectivity of the regional innovation system hosting them. Arguably, the particular institutional features of LSRFs are conducive for collaborative...... research. However, based on data on publications produced in 2006–2009 at the Neutron Science Directorate of Oak Ridge National Laboratory in Tennessee (United States), we find that internationalization of its collaborative research is restrained by coordination costs similar to those characterizing other...

  18. Novel algorithm of large-scale simultaneous linear equations

    International Nuclear Information System (INIS)

    Fujiwara, T; Hoshi, T; Yamamoto, S; Sogabe, T; Zhang, S-L

    2010-01-01

    We review our recently developed methods of solving large-scale simultaneous linear equations and applications to electronic structure calculations both in one-electron theory and many-electron theory. This is the shifted COCG (conjugate orthogonal conjugate gradient) method based on the Krylov subspace, and the most important issue for applications is the shift equation and the seed switching method, which greatly reduce the computational cost. The applications to nano-scale Si crystals and the double orbital extended Hubbard model are presented.

  19. Optimization of large scale food production using Lean Manufacturing principles

    DEFF Research Database (Denmark)

    Engelund, Eva Høy; Friis, Alan; Breum, Gitte

    2009-01-01

    This paper discusses how the production principles of Lean Manufacturing (Lean) can be applied in a large-scale meal production. Lean principles are briefly presented, followed by a field study of how a kitchen at a Danish hospital has implemented Lean in the daily production. In the kitchen...... not be negatively affected by the rationalisation of production procedures. The field study shows that Lean principles can be applied in meal production and can result in increased production efficiency and systematic improvement of product quality without negative effects on the working environment. The results...... show that Lean can be applied and used to manage the production of meals in the kitchen....

  20. Composite and case study analyses of the large-scale environments associated with West Pacific Polar and subtropical vertical jet superposition events

    Science.gov (United States)

    Handlos, Zachary J.

    Though considerable research attention has been devoted to examination of the Northern Hemispheric polar and subtropical jet streams, relatively little has been directed toward understanding the circumstances that conspire to produce the relatively rare vertical superposition of these usually separate features. This dissertation investigates the structure and evolution of large-scale environments associated with jet superposition events in the northwest Pacific. An objective identification scheme, using NCEP/NCAR Reanalysis 1 data, is employed to identify all jet superpositions in the west Pacific (30-40°N, 135-175°E) for boreal winters (DJF) between 1979/80 - 2009/10. The analysis reveals that environments conducive to west Pacific jet superposition share several large-scale features usually associated with East Asian Winter Monsoon (EAWM) northerly cold surges, including the presence of an enhanced Hadley Cell-like circulation within the jet entrance region. It is further demonstrated that several EAWM indices are statistically significantly correlated with jet superposition frequency in the west Pacific. The life cycle of EAWM cold surges promotes interaction between tropical convection and internal jet dynamics. Low potential vorticity (PV), high theta e tropical boundary layer air, exhausted by anomalous convection in the west Pacific lower latitudes, is advected poleward towards the equatorward side of the jet in upper tropospheric isentropic layers resulting in anomalous anticyclonic wind shear that accelerates the jet. This, along with geostrophic cold air advection in the left jet entrance region that drives the polar tropopause downward through the jet core, promotes the development of the deep, vertical PV wall characteristic of superposed jets. West Pacific jet superpositions preferentially form within an environment favoring the aforementioned characteristics regardless of EAWM seasonal strength. Post-superposition, it is shown that the west Pacific

  1. Topographically Engineered Large Scale Nanostructures for Plasmonic Biosensing

    Science.gov (United States)

    Xiao, Bo; Pradhan, Sangram K.; Santiago, Kevin C.; Rutherford, Gugu N.; Pradhan, Aswini K.

    2016-04-01

    We demonstrate that a nanostructured metal thin film can achieve enhanced transmission efficiency and sharp resonances and use a large-scale and high-throughput nanofabrication technique for the plasmonic structures. The fabrication technique combines the features of nanoimprint and soft lithography to topographically construct metal thin films with nanoscale patterns. Metal nanogratings developed using this method show significantly enhanced optical transmission (up to a one-order-of-magnitude enhancement) and sharp resonances with full width at half maximum (FWHM) of ~15nm in the zero-order transmission using an incoherent white light source. These nanostructures are sensitive to the surrounding environment, and the resonance can shift as the refractive index changes. We derive an analytical method using a spatial Fourier transformation to understand the enhancement phenomenon and the sensing mechanism. The use of real-time monitoring of protein-protein interactions in microfluidic cells integrated with these nanostructures is demonstrated to be effective for biosensing. The perpendicular transmission configuration and large-scale structures provide a feasible platform without sophisticated optical instrumentation to realize label-free surface plasmon resonance (SPR) sensing.

  2. Large-scale hydrogen production using nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ryland, D.; Stolberg, L.; Kettner, A.; Gnanapragasam, N.; Suppiah, S. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    2014-07-01

    For many years, Atomic Energy of Canada Limited (AECL) has been studying the feasibility of using nuclear reactors, such as the Supercritical Water-cooled Reactor, as an energy source for large scale hydrogen production processes such as High Temperature Steam Electrolysis and the Copper-Chlorine thermochemical cycle. Recent progress includes the augmentation of AECL's experimental capabilities by the construction of experimental systems to test high temperature steam electrolysis button cells at ambient pressure and temperatures up to 850{sup o}C and CuCl/HCl electrolysis cells at pressures up to 7 bar and temperatures up to 100{sup o}C. In parallel, detailed models of solid oxide electrolysis cells and the CuCl/HCl electrolysis cell are being refined and validated using experimental data. Process models are also under development to assess options for economic integration of these hydrogen production processes with nuclear reactors. Options for large-scale energy storage, including hydrogen storage, are also under study. (author)

  3. The effective field theory of cosmological large scale structures

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco, John Joseph M. [Stanford Univ., Stanford, CA (United States); Hertzberg, Mark P. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Senatore, Leonardo [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2012-09-20

    Large scale structure surveys will likely become the next leading cosmological probe. In our universe, matter perturbations are large on short distances and small at long scales, i.e. strongly coupled in the UV and weakly coupled in the IR. To make precise analytical predictions on large scales, we develop an effective field theory formulated in terms of an IR effective fluid characterized by several parameters, such as speed of sound and viscosity. These parameters, determined by the UV physics described by the Boltzmann equation, are measured from N-body simulations. We find that the speed of sound of the effective fluid is c2s ≈ 10–6c2 and that the viscosity contributions are of the same order. The fluid describes all the relevant physics at long scales k and permits a manifestly convergent perturbative expansion in the size of the matter perturbations δ(k) for all the observables. As an example, we calculate the correction to the power spectrum at order δ(k)4. As a result, the predictions of the effective field theory are found to be in much better agreement with observation than standard cosmological perturbation theory, already reaching percent precision at this order up to a relatively short scale k ≃ 0.24h Mpc–1.

  4. Systematic renormalization of the effective theory of Large Scale Structure

    International Nuclear Information System (INIS)

    Abolhasani, Ali Akbar; Mirbabayi, Mehrdad; Pajer, Enrico

    2016-01-01

    A perturbative description of Large Scale Structure is a cornerstone of our understanding of the observed distribution of matter in the universe. Renormalization is an essential and defining step to make this description physical and predictive. Here we introduce a systematic renormalization procedure, which neatly associates counterterms to the UV-sensitive diagrams order by order, as it is commonly done in quantum field theory. As a concrete example, we renormalize the one-loop power spectrum and bispectrum of both density and velocity. In addition, we present a series of results that are valid to all orders in perturbation theory. First, we show that while systematic renormalization requires temporally non-local counterterms, in practice one can use an equivalent basis made of local operators. We give an explicit prescription to generate all counterterms allowed by the symmetries. Second, we present a formal proof of the well-known general argument that the contribution of short distance perturbations to large scale density contrast δ and momentum density π(k) scale as k 2 and k, respectively. Third, we demonstrate that the common practice of introducing counterterms only in the Euler equation when one is interested in correlators of δ is indeed valid to all orders.

  5. Evaluating Unmanned Aerial Platforms for Cultural Heritage Large Scale Mapping

    Science.gov (United States)

    Georgopoulos, A.; Oikonomou, C.; Adamopoulos, E.; Stathopoulou, E. K.

    2016-06-01

    When it comes to large scale mapping of limited areas especially for cultural heritage sites, things become critical. Optical and non-optical sensors are developed to such sizes and weights that can be lifted by such platforms, like e.g. LiDAR units. At the same time there is an increase in emphasis on solutions that enable users to get access to 3D information faster and cheaper. Considering the multitude of platforms, cameras and the advancement of algorithms in conjunction with the increase of available computing power this challenge should and indeed is further investigated. In this paper a short review of the UAS technologies today is attempted. A discussion follows as to their applicability and advantages, depending on their specifications, which vary immensely. The on-board cameras available are also compared and evaluated for large scale mapping. Furthermore a thorough analysis, review and experimentation with different software implementations of Structure from Motion and Multiple View Stereo algorithms, able to process such dense and mostly unordered sequence of digital images is also conducted and presented. As test data set, we use a rich optical and thermal data set from both fixed wing and multi-rotor platforms over an archaeological excavation with adverse height variations and using different cameras. Dense 3D point clouds, digital terrain models and orthophotos have been produced and evaluated for their radiometric as well as metric qualities.

  6. Detecting differential protein expression in large-scale population proteomics

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Soyoung; Qian, Weijun; Camp, David G.; Smith, Richard D.; Tompkins, Ronald G.; Davis, Ronald W.; Xiao, Wenzhong

    2014-06-17

    Mass spectrometry-based high-throughput quantitative proteomics shows great potential in clinical biomarker studies, identifying and quantifying thousands of proteins in biological samples. However, methods are needed to appropriately handle issues/challenges unique to mass spectrometry data in order to detect as many biomarker proteins as possible. One issue is that different mass spectrometry experiments generate quite different total numbers of quantified peptides, which can result in more missing peptide abundances in an experiment with a smaller total number of quantified peptides. Another issue is that the quantification of peptides is sometimes absent, especially for less abundant peptides and such missing values contain the information about the peptide abundance. Here, we propose a Significance Analysis for Large-scale Proteomics Studies (SALPS) that handles missing peptide intensity values caused by the two mechanisms mentioned above. Our model has a robust performance in both simulated data and proteomics data from a large clinical study. Because varying patients’ sample qualities and deviating instrument performances are not avoidable for clinical studies performed over the course of several years, we believe that our approach will be useful to analyze large-scale clinical proteomics data.

  7. IP over optical multicasting for large-scale video delivery

    Science.gov (United States)

    Jin, Yaohui; Hu, Weisheng; Sun, Weiqiang; Guo, Wei

    2007-11-01

    In the IPTV systems, multicasting will play a crucial role in the delivery of high-quality video services, which can significantly improve bandwidth efficiency. However, the scalability and the signal quality of current IPTV can barely compete with the existing broadcast digital TV systems since it is difficult to implement large-scale multicasting with end-to-end guaranteed quality of service (QoS) in packet-switched IP network. China 3TNet project aimed to build a high performance broadband trial network to support large-scale concurrent streaming media and interactive multimedia services. The innovative idea of 3TNet is that an automatic switched optical networks (ASON) with the capability of dynamic point-to-multipoint (P2MP) connections replaces the conventional IP multicasting network in the transport core, while the edge remains an IP multicasting network. In this paper, we will introduce the network architecture and discuss challenges in such IP over Optical multicasting for video delivery.

  8. Power suppression at large scales in string inflation

    Energy Technology Data Exchange (ETDEWEB)

    Cicoli, Michele [Dipartimento di Fisica ed Astronomia, Università di Bologna, via Irnerio 46, Bologna, 40126 (Italy); Downes, Sean; Dutta, Bhaskar, E-mail: mcicoli@ictp.it, E-mail: sddownes@physics.tamu.edu, E-mail: dutta@physics.tamu.edu [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX, 77843-4242 (United States)

    2013-12-01

    We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters.

  9. ANTITRUST ISSUES IN THE LARGE-SCALE FOOD DISTRIBUTION SECTOR

    Directory of Open Access Journals (Sweden)

    Enrico Adriano Raffaelli

    2014-12-01

    Full Text Available In light of the slow modernization of the Italian large-scale food distribution sector, of the fragmentation at national level, of the significant roles of the cooperatives at local level and of the alliances between food retail chains, the ICA during the recent years has developed a strong interest in this sector.After having analyzed the peculiarities of the Italian large-scale food distribution sector, this article shows the recent approach taken by the ICA toward the main antitrust issues in this sector.In the analysis of such issues, mainly the contractual relations between the GDO retailers and their suppliers, the introduction of Article 62 of Law no. 27 dated 24th March 2012 is crucial, because, by facilitating and encouraging complaints by the interested parties, it should allow the developing of normal competitive dynamics within the food distribution sector, where companies should be free to enter the market using the tools at their disposal, without undue restrictions.

  10. Mapping spatial patterns of denitrifiers at large scales (Invited)

    Science.gov (United States)

    Philippot, L.; Ramette, A.; Saby, N.; Bru, D.; Dequiedt, S.; Ranjard, L.; Jolivet, C.; Arrouays, D.

    2010-12-01

    Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. Here we combined molecular approaches and geostatistical modeling to explore spatial patterns of the denitrifying community at large scales. The distribution of denitrifrying community was investigated over 107 sites in Burgundy, a 31 500 km2 region of France, using a 16 X 16 km sampling grid. At each sampling site, the abundances of denitrifiers and 42 soil physico-chemical properties were measured. The relative contributions of land use, spatial distance, climatic conditions, time and soil physico-chemical properties to the denitrifier spatial distribution were analyzed by canonical variation partitioning. Our results indicate that 43% to 85% of the spatial variation in community abundances could be explained by the measured environmental parameters, with soil chemical properties (mostly pH) being the main driver. We found spatial autocorrelation up to 739 km and used geostatistical modelling to generate predictive maps of the distribution of denitrifiers at the landscape scale. Studying the distribution of the denitrifiers at large scale can help closing the artificial gap between the investigation of microbial processes and microbial community ecology, therefore facilitating our understanding of the relationships between the ecology of denitrifiers and N-fluxes by denitrification.

  11. State-of-the-art of large scale biogas plants

    International Nuclear Information System (INIS)

    Prisum, J.M.; Noergaard, P.

    1992-01-01

    A survey of the technological state of large scale biogas plants in Europe treating manure is given. 83 plants are in operation at present. Of these, 16 are centralised digestion plants. Transport costs at centralised digestion plants amounts to between 25 and 40 percent of the total operational costs. Various transport equipment is used. Most large scale digesters are CSTRs, but serial, contact, 2-step, and plug-flow digesters are also found. Construction materials are mostly steel and concrete. Mesophilic digestion is most common (56%), thermophilic digestion is used in 17% of the plants, combined mesophilic and thermophilic digestion is used in 28% of the centralised plants. Mixing of digester content is performed with gas injection, propellers, and gas-liquid displacement. Heating is carried out using external or internal heat exchangers. Heat recovery is only used in Denmark. Gas purification equipment is commonplace, but not often needed. Several plants use separation of the digested manure, often as part of a post-treatment/-purification process or for the production of 'compost'. Screens, sieve belt separaters, centrifuges and filter presses are employed. The use of biogas varies considerably. In some cases, combined heat and power stations are supplying the grid and district heating systems. Other plants use only either the electricity or heat. (au)

  12. Exploiting Data Sparsity for Large-Scale Matrix Computations

    KAUST Repository

    Akbudak, Kadir; Ltaief, Hatem; Mikhalev, Aleksandr; Charara, Ali; Keyes, David E.

    2018-01-01

    Exploiting data sparsity in dense matrices is an algorithmic bridge between architectures that are increasingly memory-austere on a per-core basis and extreme-scale applications. The Hierarchical matrix Computations on Manycore Architectures (HiCMA) library tackles this challenging problem by achieving significant reductions in time to solution and memory footprint, while preserving a specified accuracy requirement of the application. HiCMA provides a high-performance implementation on distributed-memory systems of one of the most widely used matrix factorization in large-scale scientific applications, i.e., the Cholesky factorization. It employs the tile low-rank data format to compress the dense data-sparse off-diagonal tiles of the matrix. It then decomposes the matrix computations into interdependent tasks and relies on the dynamic runtime system StarPU for asynchronous out-of-order scheduling, while allowing high user-productivity. Performance comparisons and memory footprint on matrix dimensions up to eleven million show a performance gain and memory saving of more than an order of magnitude for both metrics on thousands of cores, against state-of-the-art open-source and vendor optimized numerical libraries. This represents an important milestone in enabling large-scale matrix computations toward solving big data problems in geospatial statistics for climate/weather forecasting applications.

  13. Fuel pin integrity assessment under large scale transients

    International Nuclear Information System (INIS)

    Dutta, B.K.

    2006-01-01

    The integrity of fuel rods under normal, abnormal and accident conditions is an important consideration during fuel design of advanced nuclear reactors. The fuel matrix and the sheath form the first barrier to prevent the release of radioactive materials into the primary coolant. An understanding of the fuel and clad behaviour under different reactor conditions, particularly under the beyond-design-basis accident scenario leading to large scale transients, is always desirable to assess the inherent safety margins in fuel pin design and to plan for the mitigation the consequences of accidents, if any. The severe accident conditions are typically characterized by the energy deposition rates far exceeding the heat removal capability of the reactor coolant system. This may lead to the clad failure due to fission gas pressure at high temperature, large- scale pellet-clad interaction and clad melting. The fuel rod performance is affected by many interdependent complex phenomena involving extremely complex material behaviour. The versatile experimental database available in this area has led to the development of powerful analytical tools to characterize fuel under extreme scenarios

  14. Large Scale Community Detection Using a Small World Model

    Directory of Open Access Journals (Sweden)

    Ranjan Kumar Behera

    2017-11-01

    Full Text Available In a social network, small or large communities within the network play a major role in deciding the functionalities of the network. Despite of diverse definitions, communities in the network may be defined as the group of nodes that are more densely connected as compared to nodes outside the group. Revealing such hidden communities is one of the challenging research problems. A real world social network follows small world phenomena, which indicates that any two social entities can be reachable in a small number of steps. In this paper, nodes are mapped into communities based on the random walk in the network. However, uncovering communities in large-scale networks is a challenging task due to its unprecedented growth in the size of social networks. A good number of community detection algorithms based on random walk exist in literature. In addition, when large-scale social networks are being considered, these algorithms are observed to take considerably longer time. In this work, with an objective to improve the efficiency of algorithms, parallel programming framework like Map-Reduce has been considered for uncovering the hidden communities in social network. The proposed approach has been compared with some standard existing community detection algorithms for both synthetic and real-world datasets in order to examine its performance, and it is observed that the proposed algorithm is more efficient than the existing ones.

  15. Dose monitoring in large-scale flowing aqueous media

    International Nuclear Information System (INIS)

    Kuruca, C.N.

    1995-01-01

    The Miami Electron Beam Research Facility (EBRF) has been in operation for six years. The EBRF houses a 1.5 MV, 75 KW DC scanned electron beam. Experiments have been conducted to evaluate the effectiveness of high-energy electron irradiation in the removal of toxic organic chemicals from contaminated water and the disinfection of various wastewater streams. The large-scale plant operates at approximately 450 L/min (120 gal/min). The radiation dose absorbed by the flowing aqueous streams is estimated by measuring the difference in water temperature before and after it passes in front of the beam. Temperature measurements are made using resistance temperature devices (RTDs) and recorded by computer along with other operating parameters. Estimated dose is obtained from the measured temperature differences using the specific heat of water. This presentation will discuss experience with this measurement system, its application to different water presentation devices, sources of error, and the advantages and disadvantages of its use in large-scale process applications

  16. Large scale CMB anomalies from thawing cosmic strings

    Energy Technology Data Exchange (ETDEWEB)

    Ringeval, Christophe [Centre for Cosmology, Particle Physics and Phenomenology, Institute of Mathematics and Physics, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium); Yamauchi, Daisuke; Yokoyama, Jun' ichi [Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan); Bouchet, François R., E-mail: christophe.ringeval@uclouvain.be, E-mail: yamauchi@resceu.s.u-tokyo.ac.jp, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp, E-mail: bouchet@iap.fr [Institut d' Astrophysique de Paris, UMR 7095-CNRS, Université Pierre et Marie Curie, 98bis boulevard Arago, 75014 Paris (France)

    2016-02-01

    Cosmic strings formed during inflation are expected to be either diluted over super-Hubble distances, i.e., invisible today, or to have crossed our past light cone very recently. We discuss the latter situation in which a few strings imprint their signature in the Cosmic Microwave Background (CMB) Anisotropies after recombination. Being almost frozen in the Hubble flow, these strings are quasi static and evade almost all of the previously derived constraints on their tension while being able to source large scale anisotropies in the CMB sky. Using a local variance estimator on thousand of numerically simulated Nambu-Goto all sky maps, we compute the expected signal and show that it can mimic a dipole modulation at large angular scales while being negligible at small angles. Interestingly, such a scenario generically produces one cold spot from the thawing of a cosmic string loop. Mixed with anisotropies of inflationary origin, we find that a few strings of tension GU = O(1) × 10{sup −6} match the amplitude of the dipole modulation reported in the Planck satellite measurements and could be at the origin of other large scale anomalies.

  17. Literature Review: Herbal Medicine Treatment after Large-Scale Disasters.

    Science.gov (United States)

    Takayama, Shin; Kaneko, Soichiro; Numata, Takehiro; Kamiya, Tetsuharu; Arita, Ryutaro; Saito, Natsumi; Kikuchi, Akiko; Ohsawa, Minoru; Kohayagawa, Yoshitaka; Ishii, Tadashi

    2017-01-01

    Large-scale natural disasters, such as earthquakes, tsunamis, volcanic eruptions, and typhoons, occur worldwide. After the Great East Japan earthquake and tsunami, our medical support operation's experiences suggested that traditional medicine might be useful for treating the various symptoms of the survivors. However, little information is available regarding herbal medicine treatment in such situations. Considering that further disasters will occur, we performed a literature review and summarized the traditional medicine approaches for treatment after large-scale disasters. We searched PubMed and Cochrane Library for articles written in English, and Ichushi for those written in Japanese. Articles published before 31 March 2016 were included. Keywords "disaster" and "herbal medicine" were used in our search. Among studies involving herbal medicine after a disaster, we found two randomized controlled trials investigating post-traumatic stress disorder (PTSD), three retrospective investigations of trauma or common diseases, and seven case series or case reports of dizziness, pain, and psychosomatic symptoms. In conclusion, herbal medicine has been used to treat trauma, PTSD, and other symptoms after disasters. However, few articles have been published, likely due to the difficulty in designing high quality studies in such situations. Further study will be needed to clarify the usefulness of herbal medicine after disasters.

  18. Development of large-scale functional brain networks in children.

    Directory of Open Access Journals (Sweden)

    Kaustubh Supekar

    2009-07-01

    Full Text Available The ontogeny of large-scale functional organization of the human brain is not well understood. Here we use network analysis of intrinsic functional connectivity to characterize the organization of brain networks in 23 children (ages 7-9 y and 22 young-adults (ages 19-22 y. Comparison of network properties, including path-length, clustering-coefficient, hierarchy, and regional connectivity, revealed that although children and young-adults' brains have similar "small-world" organization at the global level, they differ significantly in hierarchical organization and interregional connectivity. We found that subcortical areas were more strongly connected with primary sensory, association, and paralimbic areas in children, whereas young-adults showed stronger cortico-cortical connectivity between paralimbic, limbic, and association areas. Further, combined analysis of functional connectivity with wiring distance measures derived from white-matter fiber tracking revealed that the development of large-scale brain networks is characterized by weakening of short-range functional connectivity and strengthening of long-range functional connectivity. Importantly, our findings show that the dynamic process of over-connectivity followed by pruning, which rewires connectivity at the neuronal level, also operates at the systems level, helping to reconfigure and rebalance subcortical and paralimbic connectivity in the developing brain. Our study demonstrates the usefulness of network analysis of brain connectivity to elucidate key principles underlying functional brain maturation, paving the way for novel studies of disrupted brain connectivity in neurodevelopmental disorders such as autism.

  19. Development of large-scale functional brain networks in children.

    Science.gov (United States)

    Supekar, Kaustubh; Musen, Mark; Menon, Vinod

    2009-07-01

    The ontogeny of large-scale functional organization of the human brain is not well understood. Here we use network analysis of intrinsic functional connectivity to characterize the organization of brain networks in 23 children (ages 7-9 y) and 22 young-adults (ages 19-22 y). Comparison of network properties, including path-length, clustering-coefficient, hierarchy, and regional connectivity, revealed that although children and young-adults' brains have similar "small-world" organization at the global level, they differ significantly in hierarchical organization and interregional connectivity. We found that subcortical areas were more strongly connected with primary sensory, association, and paralimbic areas in children, whereas young-adults showed stronger cortico-cortical connectivity between paralimbic, limbic, and association areas. Further, combined analysis of functional connectivity with wiring distance measures derived from white-matter fiber tracking revealed that the development of large-scale brain networks is characterized by weakening of short-range functional connectivity and strengthening of long-range functional connectivity. Importantly, our findings show that the dynamic process of over-connectivity followed by pruning, which rewires connectivity at the neuronal level, also operates at the systems level, helping to reconfigure and rebalance subcortical and paralimbic connectivity in the developing brain. Our study demonstrates the usefulness of network analysis of brain connectivity to elucidate key principles underlying functional brain maturation, paving the way for novel studies of disrupted brain connectivity in neurodevelopmental disorders such as autism.

  20. Some ecological guidelines for large-scale biomass plantations

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, W.; Cook, J.H.; Beyea, J. [National Audubon Society, Tavernier, FL (United States)

    1993-12-31

    The National Audubon Society sees biomass as an appropriate and necessary source of energy to help replace fossil fuels in the near future, but is concerned that large-scale biomass plantations could displace significant natural vegetation and wildlife habitat, and reduce national and global biodiversity. We support the development of an industry large enough to provide significant portions of our energy budget, but we see a critical need to ensure that plantations are designed and sited in ways that minimize ecological disruption, or even provide environmental benefits. We have been studying the habitat value of intensively managed short-rotation tree plantations. Our results show that these plantations support large populations of some birds, but not all of the species using the surrounding landscape, and indicate that their value as habitat can be increased greatly by including small areas of mature trees within them. We believe short-rotation plantations can benefit regional biodiversity if they can be deployed as buffers for natural forests, or as corridors connecting forest tracts. To realize these benefits, and to avoid habitat degradation, regional biomass plantation complexes (e.g., the plantations supplying all the fuel for a powerplant) need to be planned, sited, and developed as large-scale units in the context of the regional landscape mosaic.