LLNL Ocean General Circulation Model
Energy Science and Technology Software Center (OSTI)
2005-12-29
The LLNL OGCM is a numerical ocean modeling tool for use in studying ocean circulation over a wide range of space and time scales, with primary applications to climate change and carbon cycle science.
Open Geospace General Circulation Model simulation of a substorm...
Office of Scientific and Technical Information (OSTI)
Open Geospace General Circulation Model simulation of a substorm: Axial tail instability ... Country of Publication: United States Language: English Word Cloud More Like This Full ...
Posters Comparison Between General Circulation Model Simulation and Central Equatorial
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
61 Posters Comparison Between General Circulation Model Simulation and Central Equatorial Pacific Experiment Measurements G. J. Zhang, S. Sherwood, T. P. Barnett, and V. Ramanathan Scripps Institution of Oceanography University of California, San Diego La Jolla, California Introduction A general circulation model (GCM) is a very powerful tool for understanding many climate issues. However, it must be validated using observational data in order for the model results to be credible in climate
Evaluation of cirrus statistics produced by general circulation models
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using ARM data cirrus statistics produced by general circulation models using ARM data Hartsock, Daniel University of Utah Mace, Gerald University of Utah Benson, Sally University of Utah Category: Modeling Our goal is to evaluate the skill of various general circulation models for producing climatological cloud statistics by comparing them to the cirrus climatology compiled over the Southern Great Plains (SGP) ARM site. This evaluation includes quantifying similar cloud properties and
A general circulation model (GCM) parameterization of Pinatubo aerosols
Lacis, A.A.; Carlson, B.E.; Mishchenko, M.I.
1996-04-01
The June 1991 volcanic eruption of Mt. Pinatubo is the largest and best documented global climate forcing experiment in recorded history. The time development and geographical dispersion of the aerosol has been closely monitored and sampled. Based on preliminary estimates of the Pinatubo aerosol loading, general circulation model predictions of the impact on global climate have been made.
Application of Improved Radiation Modeling to General Circulation Models
Michael J Iacono
2011-04-07
This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.
Treatment of cloud radiative effects in general circulation models
Wang, W.C.; Dudek, M.P.; Liang, X.Z.; Ding, M.
1996-04-01
We participate in the Atmospheric Radiation Measurement (ARM) program with two objectives: (1) to improve the general circulation model (GCM) cloud/radiation treatment with a focus on cloud verticle overlapping and layer cloud optical properties, and (2) to study the effects of cloud/radiation-climate interaction on GCM climate simulations. This report summarizes the project progress since the Fourth ARM Science Team meeting February 28-March 4, 1994, in Charleston, South Carolina.
Single-Column Modeling A Stratiform Cloud Parameterization for General Circulation Models
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
A Stratiform Cloud Parameterization for General Circulation Models S. J. Ghan and L. R. Leung Pacific Northwest Laboratory Richland, WA 99352 C. C. Chuang and J. E. Penner Lawrence Livermore National Laboratory : Livermore. CA 94550 J. McCaa University of Washington Seattle, Washington The crude treatment of clouds in general circulation models (GCMs) is widely recognized as a major limitation in applying these models to predictions of global climate change. The purpose of this project is to
Prediction of cloud droplet number in a general circulation model
Ghan, S.J.; Leung, L.R.
1996-04-01
We have applied the Colorado State University Regional Atmospheric Modeling System (RAMS) bulk cloud microphysics parameterization to the treatment of stratiform clouds in the National Center for Atmospheric Research Community Climate Model (CCM2). The RAMS predicts mass concentrations of cloud water, cloud ice, rain and snow, and number concnetration of ice. We have introduced the droplet number conservation equation to predict droplet number and it`s dependence on aerosols.
Evaluation of a stratiform cloud parameterization for general circulation models
Ghan, S.J.; Leung, L.R.; McCaa, J.
1996-04-01
To evaluate the relative importance of horizontal advection of cloud versus cloud formation within the grid cell of a single column model (SCM), we have performed a series of simulations with our SCM driven by a fixed vertical velocity and various rates of horizontal advection.
Burtis, M.D.; Razuvaev, V.N.; Sivachok, S.G.
1996-10-01
This report presents English-translated abstracts of important Russian-language literature concerning general circulation models as they relate to climate change. Into addition to the bibliographic citations and abstracts translated into English, this report presents the original citations and abstracts in Russian. Author and title indexes are included to assist the reader in locating abstracts of particular interest.
Simulation of the Low-Level-Jet by general circulation models
Ghan, S.J.
1996-04-01
To what degree is the low-level jet climatology and it`s impact on clouds and precipitation being captured by current general circulation models? It is hypothesised that a need for a pramaterization exists. This paper describes this parameterization need.
Evans, J.L.; Frank, W.M.; Young, G.S.
1996-04-01
Successful simulations of the global circulation and climate require accurate representation of the properties of shallow and deep convective clouds, stable-layer clouds, and the interactions between various cloud types, the boundary layer, and the radiative fluxes. Each of these phenomena play an important role in the global energy balance, and each must be parameterized in a global climate model. These processes are highly interactive. One major problem limiting the accuracy of parameterizations of clouds and other processes in general circulation models (GCMs) is that most of the parameterization packages are not linked with a common physical basis. Further, these schemes have not, in general, been rigorously verified against observations adequate to the task of resolving subgrid-scale effects. To address these problems, we are designing a new Integrated Cumulus Ensemble and Turbulence (ICET) parameterization scheme, installing it in a climate model (CCM2), and evaluating the performance of the new scheme using data from Atmospheric Radiation Measurement (ARM) Program Cloud and Radiation Testbed (CART) sites.
A comparison of general circulation model predictions to sand drift and dune orientations
Blumberg, D.G.; Greeley, R.
1996-12-01
The growing concern over climate change and decertification stresses the importance of aeolian process prediction. In this paper the use of a general circulation model to predict current aeolian features is examined. A GCM developed at NASA/Goddard Space Flight Center was used in conjunction with White`s aeolian sand flux model to produce a global potential aeolian transport map. Surface wind shear stress predictions were used from the output of a GCM simulation that was performed as part of the Atmospheric Model Intercomparison Project on 1979 climate conditions. The spatial resolution of this study (as driven by the GCM) is 4{degrees} X 5{degrees}; instantaneous 6-hourly wind stress data were saved by the GCM and used in this report. A global map showing potential sand transport was compared to drift potential directions as inferred from Landsat images from the 1980s for several sand seas and a coastal dune field. Generally, results show a good correlation between the simulated sand drift direction and the drift direction inferred for dune forms. Discrepancies between the drift potential and the drift inferred from images were found in the North American deserts and the Arabian peninsula. An attempt to predict the type of dune that would be formed in specific regions was not successful. The model could probably be further improved by incorporating soil moisture, surface roughness, and vegetation information for a better assessment of sand threshold conditions. The correlation may permit use of a GCM to analyze {open_quotes}fossil{close_quotes} dunes or to forecast aeolian processes. 48 refs., 8 figs.
Wan, Hui; Rasch, Philip J.; Zhang, Kai; Qian, Yun; Yan, Huiping; Zhao, Chun
2014-09-08
This paper explores the feasibility of an experimentation strategy for investigating sensitivities in fast components of atmospheric general circulation models. The basic idea is to replace the traditional serial-in-time long-term climate integrations by representative ensembles of shorter simulations. The key advantage of the proposed method lies in its efficiency: since fewer days of simulation are needed, the computational cost is less, and because individual realizations are independent and can be integrated simultaneously, the new dimension of parallelism can dramatically reduce the turnaround time in benchmark tests, sensitivities studies, and model tuning exercises. The strategy is not appropriate for exploring sensitivity of all model features, but it is very effective in many situations. Two examples are presented using the Community Atmosphere Model version 5. The first example demonstrates that the method is capable of characterizing the model cloud and precipitation sensitivity to time step length. A nudging technique is also applied to an additional set of simulations to help understand the contribution of physics-dynamics interaction to the detected time step sensitivity. In the second example, multiple empirical parameters related to cloud microphysics and aerosol lifecycle are perturbed simultaneously in order to explore which parameters have the largest impact on the simulated global mean top-of-atmosphere radiation balance. Results show that in both examples, short ensembles are able to correctly reproduce the main signals of model sensitivities revealed by traditional long-term climate simulations for fast processes in the climate system. The efficiency of the ensemble method makes it particularly useful for the development of high-resolution, costly and complex climate models.
The Madden-Julian oscillation in ECHAM4 coupled and uncoupled general circulation models
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Sperber, Kenneth R.; Gualdi, Silvio; Legutke, Stephanie; Gayler, Veronika
2005-06-29
The Madden-Julian oscillation (MJO) dominates tropical variability on timescales of 30–70 days. During the boreal winter/spring, it is manifested as an eastward propagating disturbance, with a strong convective signature over the eastern hemisphere. The space–time structure of the MJO is analyzed using simulations with the ECHAM4 atmospheric general circulation model run with observed monthly mean sea-surface temperatures (SSTs), and coupled to three different ocean models. The coherence of the eastward propagation of MJO convection is sensitive to the ocean model to which ECHAM4 is coupled. For ECHAM4/OPYC and ECHO-G, models for which ~100 years of daily data is available, Montemore » Carlo sampling indicates that their metrics of eastward propagation are different at the 1% significance level. The flux-adjusted coupled simulations, ECHAM4/OPYC and ECHO-G, maintain a more realistic mean-state, and have a more realistic MJO simulation than the nonadjusted scale interaction experiment (SINTEX) coupled runs. The SINTEX model exhibits a cold bias in Indian Ocean and tropical West Pacific Ocean sea-surface temperature of ~0.5°C. This cold bias affects the distribution of time-mean convection over the tropical eastern hemisphere. Furthermore, the eastward propagation of MJO convection in this model is not as coherent as in the two models that used flux adjustment or when compared to an integration of ECHAM4 with prescribed observed SST. This result suggests that simulating a realistic basic state is at least as important as air–sea interaction for organizing the MJO. While all of the coupled models simulate the warm (cold) SST anomalies that precede (succeed) the MJO convection, the interaction of the components of the net surface heat flux that lead to these anomalies are different over the Indian Ocean. The ECHAM4/OPYC model in which the atmospheric model is run at a horizontal resolution of T42, has eastward propagating zonal wind anomalies and latent heat
Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E.; Gettelman, Andrew; Lohmann, Ulrike; Bellouin, Nicolas; Boucher, Olivier; Sayer, Andrew M.; Thomas, Gareth E.; McComiskey, Allison; Feingold, Graham; Hoose, Corinna; Kristjansson, Jon Egill; Liu, Xiaohong; Balkanski, Yves; Donner, Leo J.; Ginoux, Paul A.; Stier, Philip; Feichter, Johann; Sednev, Igor; Bauer, Susanne E.; Koch, Dorothy; Grainger, Roy G.; Kirkevag, Alf; Iversen, Trond; Seland, Oyvind; Easter, Richard; Ghan, Steven J.; Rasch, Philip J.; Morrison, Hugh; Lamarque, Jean-Francois; Iacono, Michael J.; Kinne, Stefan; Schulz, Michael
2009-04-10
Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterizes aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth (Ta) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (Nd) compares relatively well to the satellite data at least over the ocean. The relationship between Ta and liquid water path is simulated much too strongly by the models. It is shown that this is partly related to the representation of the second aerosol indirect effect in terms of autoconversion. A positive relationship between total cloud fraction (fcld) and Ta as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong fcld - Ta relationship, our results indicate that none can be identified as unique explanation. Relationships similar to the ones found in satellite data between Ta and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - Ta relationship show a strong positive correlation between Ta and fcld The short-wave total aerosol radiative forcing as simulated by the GCMs is strongly influenced by the simulated anthropogenic fraction of Ta, and parameterisation assumptions such as a lower bound on Nd
Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E.; Gettelman, Andrew; Lohmann, Ulrike; Bellouin, Nicolas; Boucher, Olivier; Sayer, Andrew M.; Thomas, Gareth E.; McComiskey, Allison; Feingold, Graham; Hoose, Corinna; Kristansson, Jon Egill; Liu, Xiaohong; Balkanski, Yves; Donner, Leo J.; Ginoux, Paul A.; Stier, Philip; Grandey, Benjamin; Feichter, Johann; Sednev, Igor; Bauer, Susanne E.; Koch, Dorothy; Grainger, Roy G.; Kirkevag, Alf; Iversen, Trond; Seland, Oyvind; Easter, Richard; Ghan, Steven J.; Rasch, Philip J.; Morrison, Hugh; Lamarque, Jean-Francois; Iacono, Michael J.; Kinne, Stefan; Schulz, Michael
2010-03-12
Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterises aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth ({tau}{sub a}) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (N{sub d}) compares relatively well to the satellite data at least over the ocean. The relationship between {tau}{sub a} and liquid water path is simulated much too strongly by the models. This suggests that the implementation of the second aerosol indirect effect mainly in terms of an autoconversion parameterisation has to be revisited in the GCMs. A positive relationship between total cloud fraction (f{sub cld}) and {tau}{sub a} as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong f{sub cld} - {tau}{sub a} relationship, our results indicate that none can be identified as a unique explanation. Relationships similar to the ones found in satellite data between {tau}{sub a} and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - {tau}{sub a} relationship show a strong positive correlation between {tau}{sub a} and f{sub cld} The short-wave total aerosol radiative forcing as simulated by the GCMs is
Modeling of Arctic Storms with a Variable High-Resolution General Circulation Model
Taylor, Mark A.; Roesler, Erika Louise; Bosler, Peter Andrew
2015-08-01
The Department of Energy’s (DOE) Biological and Environmental Research project, “Water Cycle and Climate Extremes Modeling” is improving our understanding and modeling of regional details of the Earth’s water cycle. Sandia is using high resolution model behavior to investigate storms in the Arctic.
Saenz, Juan A.; Chen, Qingshan; Ringler, Todd
2015-05-19
Recent work has shown that taking the thickness-weighted average (TWA) of the Boussinesq equations in buoyancy coordinates results in exact equations governing the prognostic residual mean flow where eddy–mean flow interactions appear in the horizontal momentum equations as the divergence of the Eliassen–Palm flux tensor (EPFT). It has been proposed that, given the mathematical tractability of the TWA equations, the physical interpretation of the EPFT, and its relation to potential vorticity fluxes, the TWA is an appropriate framework for modeling ocean circulation with parameterized eddies. The authors test the feasibility of this proposition and investigate the connections between the TWA framework and the conventional framework used in models, where Eulerian mean flow prognostic variables are solved for. Using the TWA framework as a starting point, this study explores the well-known connections between vertical transfer of horizontal momentum by eddy form drag and eddy overturning by the bolus velocity, used by Greatbatch and Lamb and Gent and McWilliams to parameterize eddies. After implementing the TWA framework in an ocean general circulation model, we verify our analysis by comparing the flows in an idealized Southern Ocean configuration simulated using the TWA and conventional frameworks with the same mesoscale eddy parameterization.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Saenz, Juan A.; Chen, Qingshan; Ringler, Todd
2015-05-19
Recent work has shown that taking the thickness-weighted average (TWA) of the Boussinesq equations in buoyancy coordinates results in exact equations governing the prognostic residual mean flow where eddy–mean flow interactions appear in the horizontal momentum equations as the divergence of the Eliassen–Palm flux tensor (EPFT). It has been proposed that, given the mathematical tractability of the TWA equations, the physical interpretation of the EPFT, and its relation to potential vorticity fluxes, the TWA is an appropriate framework for modeling ocean circulation with parameterized eddies. The authors test the feasibility of this proposition and investigate the connections between the TWAmore » framework and the conventional framework used in models, where Eulerian mean flow prognostic variables are solved for. Using the TWA framework as a starting point, this study explores the well-known connections between vertical transfer of horizontal momentum by eddy form drag and eddy overturning by the bolus velocity, used by Greatbatch and Lamb and Gent and McWilliams to parameterize eddies. After implementing the TWA framework in an ocean general circulation model, we verify our analysis by comparing the flows in an idealized Southern Ocean configuration simulated using the TWA and conventional frameworks with the same mesoscale eddy parameterization.« less
Whetton, P.H.; Pittock, A.B.; Haylock, M.R. ); Rayner, P.J. )
1994-03-01
To assist in estimating likely future climate change in the Australian region, the authors examine the results of four different general circulation modeling experiments run to assess the equilibrium impact of doubling greenhouse gases. The results examined were the most recent available at the time of study from various research centers in North America and Europe, as well as those of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The approach used is, first, to assess the quality of the control (1 x CO[sub 2]) simulations from each of the models of mean sea level (MSL) pressure and precipitation in the Australian region by comparing these with the corresponding observed patterns; and, second, to then analyze the 2 x CO[sub 2] results of only those model experiments with the best control simulations. Of the models examined two are chosen on the basis of their simulation of current climate in the region: the CSIRO four-level model (CSIRO4) and the United Kingdom Meteorological Office (UKMO) model. For conditions of equivalent doubling of CO[sub 2], both models show substantial increases in surface air temperature of around 4[degrees]-6[degrees] inland and 2[degrees]-4[degrees]C in coastal regions. Both models show decreased MSL pressure over the Australian continent and increases in rainfall over northern, central, and eastern Australia, particularly in the summer half of the year. The CSIRO4 model, but not the UKMO model, also shows increased pressure to the south of the continent and decreased winter rainfall in southwest and southern Australia. Generally, field significance tests show the pattern and magnitude of the changes to be significant of CSIRO4 (for which the necessary monthly simulated data were available). 42 refs., 20 figs., 5 tabs.
Robert G. Ellingson
2004-09-28
One specific goal of the Atmospheric Radiation Measurements (ARM) program is to improve the treatment of radiative transfer in General Circulation Models (GCMs) under clear-sky, general overcast and broken cloud conditions. Our project was geared to contribute to this goal by attacking major problems associated with one of the dominant radiation components of the problem --longwave radiation. The primary long-term project objectives were to: (1) develop an optimum longwave radiation model for use in GCMs that has been calibrated with state-of-the-art observations for clear and cloudy conditions, and (2) determine how the longwave radiative forcing with an improved algorithm contributes relatively in a GCM when compared to shortwave radiative forcing, sensible heating, thermal advection and convection. The approach has been to build upon existing models in an iterative, predictive fashion. We focused on comparing calculations from a set of models with operationally observed data for clear, overcast and broken cloud conditions. The differences found through the comparisons and physical insights have been used to develop new models, most of which have been tested with new data. Our initial GCM studies used existing GCMs to study the climate model-radiation sensitivity problem. Although this portion of our initial plans was curtailed midway through the project, we anticipate that the eventual outcome of this approach will provide both a better longwave radiative forcing algorithm and from our better understanding of how longwave radiative forcing influences the model equilibrium climate, how improvements in climate prediction using this algorithm can be achieved.
Frank, William M.; Hack, James J.; Kiehl, Jeffrey T.
1997-02-24
Research on designing an integrated moist process parameterization package was carried. This work began with a study that coupled an ensemble of cloud models to a boundary layer model to examine the feasibility of such a methodology for linking boundary layer and cumulus parameterization schemes. The approach proved feasible, prompting research to design and evaluate a coupled parameterization package for GCMS. This research contributed to the development of an Integrated Cumulus Ensemble-Turbulence (ICET) parameterization package. This package incorporates a higher-order turbulence boundary layer that feeds information concerning updraft properties and the variances of temperature and water vapor to the cloud parameterizations. The cumulus ensemble model has been developed, and initial sensitivity tests have been performed in the single column model (SCM) version of CCM2. It is currently being coupled to a convective wake/gust front model. The major function of the convective wake/gust front model is to simulate the partitioning of the boundary layer into disturbed and undisturbed regions. A second function of this model is to predict the nonlinear enhancement of surface to air sensible heat and moisture fluxes that occur in convective regimes due to correlations between winds and anomalously cold, dry air from downdrafts in the gust front region. The third function of the convective wake/gust front model is to predict the amount of undisturbed boundary layer air lifted by the leading edge of the wake and the height to which this air is lifted. The development of the wake/gust front model has been completed, and it has done well in initial testing as a stand-alone component. The current task, to be completed by the end of the funding period, is to tie the wake model to a cumulus ensemble model and to install both components into the single column model version of CCM3 for evaluation. Another area of parametrization research has been focused on the representation
Cloud/Aerosol Parameterizations: Application and Improvement of General Circulation Models
Penner, Joyce
2012-06-30
One of the biggest uncertainties associated with climate models and climate forcing is the treatment of aerosols and their effects on clouds. The effect of aerosols on clouds can be divided into two components: The first indirect effect is the forcing associated with increases in droplet concentrations; the second indirect effect is the forcing associated with changes in liquid water path, cloud morphology, and cloud lifetime. Both are highly uncertain. This project applied a cloud-resolving model to understand the response of clouds under a variety of conditions to changes in aerosols. These responses are categorized according to the large-scale meteorological conditions that lead to the response. Meteorological conditions were sampled from various fields, which, together with a global aerosol model determination of the change in aerosols from present day to pre-industrial conditions, was used to determine a first order estimate of the response of global cloud fields to changes in aerosols. The response of the clouds in the NCAR CAM3 GCM coupled to our global aerosol model were tested by examining whether the response is similar to that of the cloud resolving model and methods for improving the representation of clouds and cloud/aerosol interactions were examined.
Posters Treatment of Cloud Radiative Effects in General Circulation...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
5 Posters Treatment of Cloud Radiative Effects in General Circulation Models W.-C. Wang, M. P. Dudek, X.-Z. Liang, M. Ding, L. Zhu, E. Joseph, and S. Cox Atmospheric Sciences...
Haywood, J.M.; Roberts, D.L.; Slingo, A.
1997-07-01
A new radiation code within a general circulation model is used to assess the direct solar and thermal radiative forcing by sulfate aerosol of anthropogenic origin and soot aerosol from fossil-fuel burning. The radiative effects of different aerosol profiles, relative humidity parameterizations, chemical compositions, and internal and external mixtures of the two aerosol types are investigated. The contribution to the radiative forcing from cloudy sky regions is found to be negligible for sulfate aerosol; this is in contrast to recent studies where the cloudy sky contribution was estimated using a method in which the spatial correlation between cloud amount and sulfate burden was ignored. However, the radiative forcing due to fossil-fuel soot aerosol is enhanced in cloudy regions if soot aerosol exists within or above the cloud. The global solar radiative forcing due to sulfate aerosol is estimated to be -0.38 W m{sup -2} and the global thermal radiative forcing is estimated to be +0.01 W m{sup -2}. The hemispheric mean radiative forcings vary by only about 10% for reasonable assumptions about the chemical form of the sulfate aerosol and the relative humidity dependence; the uncertainties in the aerosol loading are far more significant. If a soot/sulfate mass ratio of 0.075 is assumed, then the global solar radiative forcing weakens to -0.18 W m{sup -2} for an external mixture and weakens further for an internal mixture. Additionally, the spatial distribution of the radiative forcing shows strong negative/positive forcing contrasts that may influence the dynamical response of the atmosphere. Although these results are extremely sensitive to the adopted soot/sulfate ratio and the assumed vertical profile, they indicate that fossil-fuel soot aerosol may exert a nonnegligible radiative forcing and emphasize the need to consider each anthropogenic aerosol species. 58 refs., 8 figs., 1 tab.
Kushnir, Y.; Esbensen, S.K.
1986-12-01
The energetics of large-scale disturbances of the wintertime, Northern Hemisphere circulation are studied with the OSU two-level general circulation model. The behavior of simulated eddies with short time-scale (2.5 to 10 days) is found to be consistent with observations and with baroclinic instability theory. Eddies with long time-scales (>10 days) appear to be maintained primarily by high-latitude baroclinic energy conversions. Energy conversions characteristic of barotropic processes are found at jet stream latitudes.
Boyle, J.S.
1994-11-01
Divergence and convergence centers at 200 hPa and mean sea level pressure (MSLP) cyclones were located every 6 hr for a 10-yr general circulation model (GCM) simulation with the ECMWF (Cycle 36) for the boreal winters from 1980 to 1988. The simulation used the observed monthly mean sea surface temperature (SST) for the decade. Analysis of the frequency, location, and strength of these centers and cyclones gives insight into the dynamical response of the model to the varying SST. The results indicate that (1) the model produces reasonable climatologies of upper-level divergence and MSLP cyclones; (2) the model distribution of anomalies of divergence and convergence centers and MSLP cyclones is consistent with observations for the 1982-83 and 1986-87 El Nifio events; (3) the tropical Indian Ocean is the region of greatest divergence activity and interannual variability in the model; (4) the variability of the divergence centers is greater than that of the convergence centers; (5) strong divergence centers occur chiefly over the ocean in the midlatitudes but are more land-based in the tropics, except in the Indian Ocean; and (6) locations of divergence and convergence centers can be a useful tool for the intercomparison of global atmospheric simulations.
Tao, Wei-Kuo; Houze, Robert, A., Jr.; Zeng, Xiping
2013-03-14
This three-year project, in cooperation with Professor Bob Houze at University of Washington, has been successfully finished as planned. Both ARM (the Atmospheric Radiation Measurement Program) data and cloud-resolving model (CRM) simulations were used to identify the water budgets of clouds observed in two international field campaigns. The research results achieved shed light on several key processes of clouds in climate change (or general circulation models), which are summarized below. 1. Revealed the effect of mineral dust on mesoscale convective systems (MCSs) Two international field campaigns near a desert and a tropical coast provided unique data to drive and evaluate CRM simulations, which are TWP-ICE (the Tropical Warm Pool International Cloud Experiment) and AMMA (the African Monsoon Multidisciplinary Analysis). Studies of the two campaign data were contrasted, revealing that much mineral dust can bring about large MCSs via ice nucleation and clouds. This result was reported as a PI presentation in the 3rd ASR Science Team meeting held in Arlington, Virginia in March 2012. A paper on the studies was published in the Journal of the Atmospheric Sciences (Zeng et al. 2013). 2. Identified the effect of convective downdrafts on ice crystal concentration Using the large-scale forcing data from TWP-ICE, ARM-SGP (the Southern Great Plains) and other field campaigns, Goddard CRM simulations were carried out in comparison with radar and satellite observations. The comparison between model and observations revealed that convective downdrafts could increase ice crystal concentration by up to three or four orders, which is a key to quantitatively represent the indirect effects of ice nuclei, a kind of aerosol, on clouds and radiation in the Tropics. This result was published in the Journal of the Atmospheric Sciences (Zeng et al. 2011) and summarized in the DOE/ASR Research Highlights Summaries (see http://www.arm.gov/science/highlights/RMjY5/view). 3. Used radar
Predictive models of circulating fluidized bed combustors
Gidaspow, D.
1992-07-01
Steady flows influenced by walls cannot be described by inviscid models. Flows in circulating fluidized beds have significant wall effects. Particles in the form of clusters or layers can be seen to run down the walls. Hence modeling of circulating fluidized beds (CFB) without a viscosity is not possible. However, in interpreting Equations (8-1) and (8-2) it must be kept in mind that CFB or most other two phase flows are never in a true steady state. Then the viscosity in Equations (8-1) and (8-2) may not be the true fluid viscosity to be discussed next, but an Eddy type viscosity caused by two phase flow oscillations usually referred to as turbulence. In view of the transient nature of two-phase flow, the drag and the boundary layer thickness may not be proportional to the square root of the intrinsic viscosity but depend upon it to a much smaller extent. As another example, liquid-solid flow and settling of colloidal particles in a lamella electrosettler the settling process is only moderately affected by viscosity. Inviscid flow with settling is a good first approximation to this electric field driven process. The physical meaning of the particulate phase viscosity is described in detail in the chapter on kinetic theory. Here the conventional derivation resented in single phase fluid mechanics is generalized to multiphase flow.
Houze, Jr., Robert A.
2013-11-13
We examined cloud radar data in monsoon climates, using cloud radars at Darwin in the Australian monsoon, on a ship in the Bay of Bengal in the South Asian monsoon, and at Niamey in the West African monsoon. We followed on with a more in-depth study of the continental MCSs over West Africa. We investigated whether the West African anvil clouds connected with squall line MCSs passing over the Niamey ARM site could be simulated in a numerical model by comparing the observed anvil clouds to anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model at high resolution using six different ice-phase microphysical schemes. We carried out further simulations with a cloud-resolving model forced by sounding network budgets over the Niamey region and over the northern Australian region. We have devoted some of the effort of this project to examining how well satellite data can determine the global breadth of the anvil cloud measurements obtained at the ARM ground sites. We next considered whether satellite data could be objectively analyzed to so that their large global measurement sets can be systematically related to the ARM measurements. Further differences were detailed between the land and ocean MCS anvil clouds by examining the interior structure of the anvils with the satellite-detected the CloudSat Cloud Profiling Radar (CPR). The satellite survey of anvil clouds in the Indo-Pacific region was continued to determine the role of MCSs in producing the cloud pattern associated with the MJO.
Plugging mechanisms in a lost circulation model
Givler, R.C.
1985-01-01
The problem of lost circulation during the drilling of geothermal wells is recognized to be a serious impediment to well completion. A viable solution, in terms of an ''engineered'' plugging material, will be enhanced via analytical cognizance of possible down-hole plugging mechanisms. This paper investigates several plugging strategies that result from rudimentary, mathematical models of the mud rheology (with and without dispersed particulate). 10 refs., 7 figs.
V. Ramaswamy; L. J. Donner; J-C. Golaz; S. A. Klein
2010-06-17
This report briefly summarizes the progress made by ARM postdoctoral fellow, Yanluan Lin, at GFDL during the period from October 2008 to present. Several ARM datasets have been used for GFDL model evaluation, understanding, and improvement. This includes a new ice fall speed parameterization with riming impact and its test in GFDL AM3, evaluation of model cloud and radiation diurnal and seasonal variation using ARM CMBE data, model ice water content evaluation using ARM cirrus data, and coordination of the TWPICE global model intercomparison. The work illustrates the potential and importance of ARM data for GCM evaluation, understanding, and ultimately, improvement of GCM cloud and radiation parameterizations. Future work includes evaluation and improvement of the new dynamicsPDF cloud scheme and aerosol activation in the GFDL model.
Aerosol indirect effects - general circulation model intercomparison...
Office of Scientific and Technical Information (OSTI)
We compute statistical relationships between aerosol optical depth (a) and various cloud ... Nevertheless, the strengths of the statistical relationships are good predictors for the ...
COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS
Ibrahim, Essam A
2013-01-09
Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations to study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.
Posters A Stratiform Cloud Parameterization for General Circulation...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
P(w) is the probability distribution of vertical velocity, determined from the predicted mean and variance of vertical velocity. Application to a Single-Column Model To test the...
Optimal control of CPR procedure using hemodynamic circulation model
Lenhart, Suzanne M.; Protopopescu, Vladimir A.; Jung, Eunok
2007-12-25
A method for determining a chest pressure profile for cardiopulmonary resuscitation (CPR) includes the steps of representing a hemodynamic circulation model based on a plurality of difference equations for a patient, applying an optimal control (OC) algorithm to the circulation model, and determining a chest pressure profile. The chest pressure profile defines a timing pattern of externally applied pressure to a chest of the patient to maximize blood flow through the patient. A CPR device includes a chest compressor, a controller communicably connected to the chest compressor, and a computer communicably connected to the controller. The computer determines the chest pressure profile by applying an OC algorithm to a hemodynamic circulation model based on the plurality of difference equations.
Modeling of a coal-fired natural circulation boiler
Bhambare, K.S.; Mitra, S.K.; Gaitonde, U.N.
2007-06-15
Modeling of a natural circulation boiler for a coal-fired thermal power station is presented here. The boiler system is divided into seven subcomponents, and for each section, models based on conservation of mass, momentum, and energy are formulated. The pressure drop at various sections and the heat transfer coefficients are computed using empirical correlations. Solutions are obtained by using SIMULINK. The model is validated by comparing its steady state and dynamic responses with the actual plant data. Open loop responses of the model to the step changes in the operating parameters, such as pressure, temperature, steam flow, feed water flow, are also analyzed. The present model can be used for the development and design of effective boiler control systems.
(CO sub 2 uptake in an Ocean Circulation Model)
Siegenthaler, U.C.
1990-11-06
The traveler collaborated with Drs. J. L. Sarmiento and J. C. Orr of the Program in Atmospheric Sciences at Princeton University to finish the article A Perturbation Simulation of CO{sub 2} Uptake in an Ocean Circulation Model,'' which has been submitted to the Journal of Geophysical Research for publication. With F. Joos, a graduate student from the University of Bern, the traveler started writing a journal article describing a box model of the global carbon cycle that is an extension of the one-dimensional box-diffusion model. The traveler further collaborated with F. Joos and Dr. J. L. Sarmiento on modeling the potential enhancement of oceanic CO{sub 2} uptake by fertilizing the southern ocean with iron. A letter describing the results is currently being written for the journal Nature.
Computer modeling of a CFB (circulating fluidized bed) gasifier
Gidaspow, D.; Ding, J.
1990-06-01
The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. This report presents an extension of our cold flow modeling of a CFB given in our first quarterly report of this project and published in Numerical Methods for Multiphase Flows'' edited by I. Celik, D. Hughes, C. T. Crowe and D. Lankford, FED-Vol.91, American Society of Mechanical Engineering, pp47--56 (1990). The title of the paper is Multiphase Navier-Stokes Equation Solver'' by D. Gidaspow, J. Ding and U.K. Jayaswal. To the two dimensional code described in the above paper we added the energy equations and the conservation of species equations to describe a synthesis gas from char producer. Under the simulation conditions the injected oxygen reacted near the inlet. The solid-gas mixing was sufficiently rapid that no undesirable hot spots were produced. This simulation illustrates the code's capability to model CFB reactors. 15 refs., 20 figs.
Predictive models of circulating fluidized bed combustors. 12th technical progress report
Gidaspow, D.
1992-07-01
Steady flows influenced by walls cannot be described by inviscid models. Flows in circulating fluidized beds have significant wall effects. Particles in the form of clusters or layers can be seen to run down the walls. Hence modeling of circulating fluidized beds (CFB) without a viscosity is not possible. However, in interpreting Equations (8-1) and (8-2) it must be kept in mind that CFB or most other two phase flows are never in a true steady state. Then the viscosity in Equations (8-1) and (8-2) may not be the true fluid viscosity to be discussed next, but an Eddy type viscosity caused by two phase flow oscillations usually referred to as turbulence. In view of the transient nature of two-phase flow, the drag and the boundary layer thickness may not be proportional to the square root of the intrinsic viscosity but depend upon it to a much smaller extent. As another example, liquid-solid flow and settling of colloidal particles in a lamella electrosettler the settling process is only moderately affected by viscosity. Inviscid flow with settling is a good first approximation to this electric field driven process. The physical meaning of the particulate phase viscosity is described in detail in the chapter on kinetic theory. Here the conventional derivation resented in single phase fluid mechanics is generalized to multiphase flow.
Generalized Environment for Modeling Systems
Energy Science and Technology Software Center (OSTI)
2012-02-07
GEMS is an integrated environment that allows technical analysts, modelers, researchers, etc. to integrate and deploy models and/or decision tools with associated data to the internet for direct use by customers. GEMS does not require that the model developer know how to code or script and therefore delivers this capability to a large group of technical specialists. Customers gain the benefit of being able to execute their own scenarios directly without need for technical support.more » GEMS is a process that leverages commercial software products with specialized codes that add connectivity and unique functions to support the overall capability. Users integrate pre-existing models with a commercial product and store parameters and input trajectories in a companion commercial database. The model is then exposed into a commercial web environment and a graphical user interface (GUI) is applied by the model developer. Users execute the model through the web based GUI and GEMS manages supply of proper inputs, execution of models, routing of data to models and display of results back to users. GEMS works in layers, the following description is from the bottom up. Modelers create models in the modeling tool of their choice such as Excel, Matlab, or Fortran. They can also use models from a library of previously wrapped legacy codes (models). Modelers integrate the models (or a single model) by wrapping and connecting the models using the Phoenix Integration tool entitled ModelCenter. Using a ModelCenter/SAS plugin (DOE copyright CW-10-08) the modeler gets data from either an SAS or SQL database and sends results back to SAS or SQL. Once the model is working properly, the ModelCenter file is saved and stored in a folder location to which a SharePoint server tool created at INL is pointed. This enables the ModelCenter model to be run from SharePoint. The modeler then goes into Microsoft SharePoint and creates a graphical user interface (GUI) using the ModelCenter Web
Computable General Equilibrium Models for Sustainability Impact...
Publications, Softwaremodeling tools User Interface: Other Website: iatools.jrc.ec.europa.eudocsecolecon2006.pdf Computable General Equilibrium Models for Sustainability...
Compactlike kinks and vortices in generalized models
Bazeia, D.; Hora, E. da; Menezes, R.; Oliveira, H. P. de; Santos, C. dos
2010-06-15
This work deals with the presence of topological defects in k-field models, where the dynamics is generalized to include higher order power in the kinetic term. We investigate kinks in (1, 1) dimensions and vortices in (2, 1) dimensions, focusing on some specific features of the solutions. In particular, we show how the kinks and vortices change to compactlike solutions, controlled by the parameter used to introduce the generalized models.
Model-free adaptive control of supercritical circulating fluidized-bed boilers
Cheng, George Shu-Xing; Mulkey, Steven L
2014-12-16
A novel 3-Input-3-Output (3.times.3) Fuel-Air Ratio Model-Free Adaptive (MFA) controller is introduced, which can effectively control key process variables including Bed Temperature, Excess O2, and Furnace Negative Pressure of combustion processes of advanced boilers. A novel 7-input-7-output (7.times.7) MFA control system is also described for controlling a combined 3-Input-3-Output (3.times.3) process of Boiler-Turbine-Generator (BTG) units and a 5.times.5 CFB combustion process of advanced boilers. Those boilers include Circulating Fluidized-Bed (CFB) Boilers and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.
Simple implementation of general dark energy models
Bloomfield, Jolyon K.; Pearson, Jonathan A. E-mail: jonathan.pearson@durham.ac.uk
2014-03-01
We present a formalism for the numerical implementation of general theories of dark energy, combining the computational simplicity of the equation of state for perturbations approach with the generality of the effective field theory approach. An effective fluid description is employed, based on a general action describing single-scalar field models. The formalism is developed from first principles, and constructed keeping the goal of a simple implementation into CAMB in mind. Benefits of this approach include its straightforward implementation, the generality of the underlying theory, the fact that the evolved variables are physical quantities, and that model-independent phenomenological descriptions may be straightforwardly investigated. We hope this formulation will provide a powerful tool for the comparison of theoretical models of dark energy with observational data.
MODELING STRATEGIES TO COMPUTE NATURAL CIRCULATION USING CFD IN A VHTR AFTER A LOFA
Yu-Hsin Tung; Richard W. Johnson; Ching-Chang Chieng; Yuh-Ming Ferng
2012-11-01
A prismatic gas-cooled very high temperature reactor (VHTR) is being developed under the next generation nuclear plant program (NGNP) of the U.S. Department of Energy, Office of Nuclear Energy. In the design of the prismatic VHTR, hexagonal shaped graphite blocks are drilled to allow insertion of fuel pins, made of compacted TRISO fuel particles, and coolant channels for the helium coolant. One of the concerns for the reactor design is the effects of a loss of flow accident (LOFA) where the coolant circulators are lost for some reason, causing a loss of forced coolant flow through the core. In such an event, it is desired to know what happens to the (reduced) heat still being generated in the core and if it represents a problem for the fuel compacts, the graphite core or the reactor vessel (RV) walls. One of the mechanisms for the transport of heat out of the core is by the natural circulation of the coolant, which is still present. That is, how much heat may be transported by natural circulation through the core and upwards to the top of the upper plenum? It is beyond current capability for a computational fluid dynamic (CFD) analysis to perform a calculation on the whole RV with a sufficiently refined mesh to examine the full potential of natural circulation in the vessel. The present paper reports the investigation of several strategies to model the flow and heat transfer in the RV. It is found that it is necessary to employ representative geometries of the core to estimate the heat transfer. However, by taking advantage of global and local symmetries, a detailed estimate of the strength of the resulting natural circulation and the level of heat transfer to the top of the upper plenum is obtained.
A zonally averaged, three-basin ocean circulation model for climate studies
Hovine, S.; Fichefet, T.
1994-09-01
A two-dimensional, three-basin ocean model suitable for long-term climate studies is developed. The model is based on the zonally averaged form of the primitive equations written in spherical coordinates. The east-west density difference which arises upon averaging the momentum equations is taken to be proportional to the meridional density gradient. Lateral exchanges of heat and salt between the basins are explicitly resolved. Moreover, the model includes bottom topography and has representations of the Arctic Ocean and of the Weddell and Ross seas. Under realistic restoring boundary conditions, the model reproduces the global conveyor belt: deep water is formed in the Atlantic between 60 and 70{degree}N at a rate of about 17 Sv (1 Sv=10{sup 6} m{sup 3}S{sup {minus}1}) and in the vicinity of the Antarctic continent, while the Indian and Pacific basins show broad upwelling. Superimposed on this thermohaline circulation are vigorous wind-driven cells in the upper thermocline. The simulated temperature and salinity fields and the computed meridional heat transport compare reasonably well with the observational estimates. When mixed boundary conditions i.e., a restoring condition no sea-surface temperature and flux condition on sea-surface salinity are applied, the model exhibits an irregular behavior before reaching a steady state characterized by self-sustained oscillations of 8.5-y period. The conveyor-belt circulation always results at this stage. A series of perturbation experiments illustrates the ability of the model to reproduce different steady-state circulations under mixed boundary conditions. Finally, the model sensitivity to various factors is examined. This sensitivity study reveals that the bottom topography and the presence of a submarine meridional ridge in the zone of the Drake passage play a crucial role in determining the properties of the model bottom-water masses. The importance of the seasonality of the surface forcing is also stressed.
Study of natural circulation in a VHTR after a LOFA using different turbulence models
Yu-Hsin Tung; Yuh-Ming Ferng; Richard W. Johnson; Ching-Chang Chieng
2013-10-01
Natural convection currents in the core are anticipated in the event of the failure of the gas circulator in a prismatic gas-cooled very high temperature reactor (VHTR). The paths that the helium coolant takes in forming natural circulation loops and the effective heat transport are of interest. The heated flow in the reactor core is turbulent during normal operating conditions and at the beginning of the LOFA with forced convection, but the flow may significantly be slowed down after the event and laminarized with mixed convection. In the present study, the potential occurrence and effective heat transport of natural circulation are demonstrated using computational fluid dynamic (CFD) calculations with different turbulence models as well as laminar flow. Validations and recommendation on turbulence model selection are conducted. The study concludes that large loop natural convection is formed due to the enhanced turbulence levels by the buoyancy effect and the turbulent regime near the interface of upper plenum and flow channels increases the flow resistance for channel flows entering upper plenum and thus less heat can be removed from the core than the prediction by laminar flow assumption.
Responses of estuarine circulation and salinity to the loss of intertidal flats – A modeling study
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Yang, Zhaoqing; Wang, Taiping
2015-08-25
Intertidal flats in estuaries are coastal wetlands that provide critical marine habitats to support wide ranges of marine species. Over the last century many estuarine systems have experienced significant loss of intertidal flats due to anthropogenic impacts. This paper presents a modeling study conducted to investigate the responses of estuarine hydrodynamics to the loss of intertidal flats caused by anthropogenic actions in Whidbey Basin of Puget Sound on the northwest coast of North America. Changes in salinity intrusion limits in the estuaries, salinity stratification, and circulation in intertidal flats and estuaries were evaluated by comparing model results under the existingmore » baseline condition and the no-flat condition. Model results showed that loss of intertidal flats results in an increase in salinity intrusion, stronger mixing, and a phase shift in salinity and velocity fields in the bay front areas. Model results also indicated that loss of intertidal flats enhances two-layer circulation, especially the bottom water intrusion. Loss of intertidal flats increases the mean salinity but reduces the salinity range in the subtidal flats over a tidal cycle because of increased mixing. Salinity intrusion limits extend upstream in all three major rivers discharging into Whidbey Basin when no intertidal flats are present. Changes in salinity intrusion and estuarine circulation patterns due to loss of intertidal flats affect the nearshore habitat and water quality in estuaries and potentially increase risk of coastal hazards, such as storm surge and coastal flooding. Furthermore, model results suggested the importance of including intertidal flats and the wetting-and-drying process in hydrodynamic simulations when intertidal flats are present in the model domain.« less
Model for flue-gas desulfurization in a circulating dry scrubber
Neathery, J.K.
1996-01-01
A simple model was developed to describe the absorption of SO{sub 2} in a circulating dry scrubbing (CDS) process, which is a semi dry, lime-based, flue-gas desulfurization (FGD) process that utilizes a circulating fluidized bed arrangement for contacting a sorbent with SO{sub 2}-laden flue gas under coolside conditions. The reaction chemistry is thought to be similar to that of spray-drying absorption. The liquid-phase mass-transfer coefficient was successfully modeled as a function of the sorbent particle spacing on the wetted surfaces. Gas-phase mass-transfer resistances were assumed to be insignificant. Due to the high surface area available in a CDS reactor, the evaporation rate of water from the slurry was modeled as constant-rate drying according to classic spray-dryer theory. However, the falling-rate and diffusion evaporation stages were negligible in CDS since sorbent particle bunching at the surface of the slurry is nonexistent.
New model for nucleon generalized parton distributions
Radyushkin, Anatoly V.
2014-01-01
We describe a new type of models for nucleon generalized parton distributions (GPDs) H and E. They are heavily based on the fact nucleon GPDs require to use two forms of double distribution (DD) representations. The outcome of the new treatment is that the usual DD+D-term construction should be amended by an extra term, {xi} E{sub +}{sup 1} (x,{xi}) which has the DD structure {alpha}/{beta} e({beta},{alpha}, with e({beta},{alpha}) being the DD that generates GPD E(x,{xi}). We found that this function, unlike the D-term, has support in the whole -1 <= x <= 1 region. Furthermore, it does not vanish at the border points |x|={xi}.
General single phase wellbore flow model
Ouyang, Liang-Biao; Arbabi, S.; Aziz, K.
1997-02-05
A general wellbore flow model, which incorporates not only frictional, accelerational and gravitational pressure drops, but also the pressure drop caused by inflow, is presented in this report. The new wellbore model is readily applicable to any wellbore perforation patterns and well completions, and can be easily incorporated in reservoir simulators or analytical reservoir inflow models. Three dimensionless numbers, the accelerational to frictional pressure gradient ratio R{sub af}, the gravitational to frictional pressure gradient ratio R{sub gf}, and the inflow-directional to accelerational pressure gradient ratio R{sub da}, have been introduced to quantitatively describe the relative importance of different pressure gradient components. For fluid flow in a production well, it is expected that there may exist up to three different regions of the wellbore: the laminar flow region, the partially-developed turbulent flow region, and the fully-developed turbulent flow region. The laminar flow region is located near the well toe, the partially-turbulent flow region lies in the middle of the wellbore, while the fully-developed turbulent flow region is at the downstream end or the heel of the wellbore. Length of each region depends on fluid properties, wellbore geometry and flow rate. As the distance from the well toe increases, flow rate in the wellbore increases and the ratios R{sub af} and R{sub da} decrease. Consequently accelerational and inflow-directional pressure drops have the greatest impact in the toe region of the wellbore. Near the well heel the local wellbore flow rate becomes large and close to the total well production rate, here R{sub af} and R{sub da} are small, therefore, both the accelerational and inflow-directional pressure drops can be neglected.
Xie, L.; Pietrafesa, L.J.; Raman, S.
1997-03-18
Interactions between surface winds and ocean currents over an east-coast continental shelf are studied using a simple mathematical model. The model physics include cross-shelf advection of sea surface temperature (SST) by Ekman drift, upwelling due to Ekman transport divergence, differential heating of the low-level atmosphere by a cross-shelf SST gradient, and the Coriolis effect. Additionally, the effects of diabatic cooling of surface waters due to air-sea heat exchange and of the vertical density stratification on the thickness of the upper ocean Ekman layer are considered. The model results are qualitatively consistent with observed wind-driven coastal ocean circulation and surface wind signatures induced by SST. This simple model also demonstrates that two-way air-sea interaction plays a significant role in the subtidal frequency variability of coastal ocean circulation and mesoscale variability of surface wind fields over coastal waters.
A general simulation model for Stirling cycles
Schulz, S.; Schwendig, F.
1996-01-01
A mathematical model for the calculation of the Stirling cycle and of similar processes is presented. The model comprises a method to reproduce schematically any kind of process configuration, including free piston engines. The differential balance equations describing the process are solved by a stable integration algorithm. Heat transfer and pressure loss are calculated by using new correlations, which consider the special conditions of the periodic compression/expansion respectively of the oscillating flow. A comparison between experimental data achieved by means of a test apparatus and calculated data shows a good agreement.
System Advisor Model, SAM 2011.12.2: General Description
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
System Advisor Model, SAM 2011.12.2: General Description Paul Gilman and Aron Dobos Technical Report NREL/TP-6A20-53437 February 2012 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401 303-275-3000 * www.nrel.gov Contract No. DE-AC36-08GO28308 System Advisor Model, SAM 2011.12.2: General Description
Generalized gas-solid adsorption modeling: Single-component equilibria
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Ladshaw, Austin; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.
2015-01-07
Over the last several decades, modeling of gas–solid adsorption at equilibrium has generally been accomplished through the use of isotherms such as the Freundlich, Langmuir, Tóth, and other similar models. While these models are relatively easy to adapt for describing experimental data, their simplicity limits their generality to be used with many different sets of data. This limitation forces engineers and scientists to test each different model in order to evaluate which one can best describe their data. Additionally, the parameters of these models all have a different physical interpretation, which may have an effect on how they can bemore » further extended into kinetic, thermodynamic, and/or mass transfer models for engineering applications. Therefore, it is paramount to adopt not only a more general isotherm model, but also a concise methodology to reliably optimize for and obtain the parameters of that model. A model of particular interest is the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm. The GSTA isotherm has enormous flexibility, which could potentially be used to describe a variety of different adsorption systems, but utilizing this model can be fairly difficult due to that flexibility. To circumvent this complication, a comprehensive methodology and computer code has been developed that can perform a full equilibrium analysis of adsorption data for any gas-solid system using the GSTA model. The code has been developed in C/C++ and utilizes a Levenberg–Marquardt’s algorithm to handle the non-linear optimization of the model parameters. Since the GSTA model has an adjustable number of parameters, the code iteratively goes through all number of plausible parameters for each data set and then returns the best solution based on a set of scrutiny criteria. Data sets at different temperatures are analyzed serially and then linear correlations with temperature are made for the parameters of the model. The end result is a full set
Generalized Optoelectronic Model of Series-Connected Multijunction Solar Cells
Geisz, John F.; Steiner, Myles A.; Garcia, Ivan; France, Ryan M.; McMahon, William E.; Osterwald, Carl R.; Friedman, Daniel J.
2015-11-01
The emission of light from each junction in a series-connected multijunction solar cell, we found, both complicates and elucidates the understanding of its performance under arbitrary conditions. Bringing together many recent advances in this understanding, we present a general 1-D model to describe luminescent coupling that arises from both voltage-driven electroluminescence and voltage-independent photoluminescence in nonideal junctions that include effects such as Sah-Noyce-Shockley (SNS) recombination with n ≠ 2, Auger recombination, shunt resistance, reverse-bias breakdown, series resistance, and significant dark area losses. The individual junction voltages and currents are experimentally determined from measured optical and electrical inputs and outputs of the device within the context of the model to fit parameters that describe the devices performance under arbitrary input conditions. Furthermore, our techniques to experimentally fit the model are demonstrated for a four-junction inverted metamorphic solar cell, and the predictions of the model are compared with concentrator flash measurements.
Generalized Optoelectronic Model of Series-Connected Multijunction Solar Cells
Geisz, John F.; Steiner, Myles A.; Garcia, Ivan; France, Ryan M.; McMahon, William E.; Osterwald, Carl R.; Friedman, Daniel J.
2015-10-02
The emission of light from each junction in a series-connected multijunction solar cell, we found, both complicates and elucidates the understanding of its performance under arbitrary conditions. Bringing together many recent advances in this understanding, we present a general 1-D model to describe luminescent coupling that arises from both voltage-driven electroluminescence and voltage-independent photoluminescence in nonideal junctions that include effects such as Sah-Noyce-Shockley (SNS) recombination with n ≠ 2, Auger recombination, shunt resistance, reverse-bias breakdown, series resistance, and significant dark area losses. The individual junction voltages and currents are experimentally determined from measured optical and electrical inputs and outputs of the device within the context of the model to fit parameters that describe the devices performance under arbitrary input conditions. Furthermore, our techniques to experimentally fit the model are demonstrated for a four-junction inverted metamorphic solar cell, and the predictions of the model are compared with concentrator flash measurements.
Fedorov, Alexey V.; Fedorov, Alexey
2015-01-14
The central goal of this research project was to understand the mechanisms of decadal and multi-decadal variability of the Atlantic Meridional Overturning Circulation (AMOC) as related to climate variability and abrupt climate change within a hierarchy of climate models ranging from realistic ocean models to comprehensive Earth system models. Generalized Stability Analysis, a method that quantifies the transient and asymptotic growth of perturbations in the system, is one of the main approaches used throughout this project. The topics we have explored range from physical mechanisms that control AMOC variability to the factors that determine AMOC predictability in the Earth system models, to the stability and variability of the AMOC in past climates.
System Advisor Model, SAM 2014.1.14: General Description
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
System Advisor Model, SAM 2014.1.14: General Description Nate Blair, Aron P. Dobos, Janine Freeman, Ty Neises, and Michael Wagner National Renewable Energy Laboratory Tom Ferguson, Paul Gilman, and Steven Janzou Independent Consultants Technical Report NREL/TP-6A20-61019 February 2014 NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy Operated by the Alliance for Sustainable Energy, LLC This report is available at no cost from the
Generalized Optoelectronic Model of Series-Connected Multijunction Solar Cells
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Geisz, John F.; Steiner, Myles A.; Garcia, Ivan; France, Ryan M.; McMahon, William E.; Osterwald, Carl R.; Friedman, Daniel J.
2015-10-02
The emission of light from each junction in a series-connected multijunction solar cell, we found, both complicates and elucidates the understanding of its performance under arbitrary conditions. Bringing together many recent advances in this understanding, we present a general 1-D model to describe luminescent coupling that arises from both voltage-driven electroluminescence and voltage-independent photoluminescence in nonideal junctions that include effects such as Sah-Noyce-Shockley (SNS) recombination with n ≠ 2, Auger recombination, shunt resistance, reverse-bias breakdown, series resistance, and significant dark area losses. The individual junction voltages and currents are experimentally determined from measured optical and electrical inputs and outputs ofmore » the device within the context of the model to fit parameters that describe the devices performance under arbitrary input conditions. Furthermore, our techniques to experimentally fit the model are demonstrated for a four-junction inverted metamorphic solar cell, and the predictions of the model are compared with concentrator flash measurements.« less
Statistical surrogate models for prediction of high-consequence...
Office of Scientific and Technical Information (OSTI)
existing coupled atmospheric models due to the high computational cost of each simulation. ... CLIMATES; DIAGNOSIS; DISTRIBUTION; FORECASTING; GENERAL CIRCULATION MODELS; METRICS; ...
Bleck, R.
2004-05-19
The overall aim of this project was to continue development of a global version of the Miami Isopycnic Coordinate Ocean Model (MICOM) with the intent of turning it into a full-fledged oceanic component of an earth system model.
A generalized Fokker-Planck model applied to beam transport
Prinja, A.K.; Pomraning, G.C.
1998-12-31
In this paper the authors consider a generalized Fokker-Planck (GFP) model for the transport of charged-particle beams, when scattering is not sufficiently forward peaked for the well-known Fokker-Planck (FP) approximation to hold. This approximation is strictly valid in the limit that the total scattering cross section {sigma}{sub s} {r_arrow} {infinity} and the mean cosine of scattering {bar {mu}} {r_arrow} 1. When scattering is not sufficiently forward peaked, higher order Fokker-Planck expansions, restricted to differential cross sections that fall off sufficiently rapidly, can be developed. For instance, the Henyey-Greenstein differential cross section does not possess an FP limit at all, while the screened Rutherford cross section satisfies the FP limit only marginally, and its higher order FP limits do not exist. For cross sections that fall off faster than screened Rutherford, including the exponential phase function, higher order truncations exist.
Generalized Modeling of Enrichment Cascades That Include Minor Isotopes
Weber, Charles F
2012-01-01
The monitoring of enrichment operations may require innovative analysis to allow for imperfect or missing data. The presence of minor isotopes may help or hurt - they can complicate a calculation or provide additional data to corroborate a calculation. However, they must be considered in a rigorous analysis, especially in cases involving reuse. This study considers matched-abundanceratio cascades that involve at least three isotopes and allows generalized input that does not require all feed assays or the enrichment factor to be specified. Calculations are based on the equations developed for the MSTAR code but are generalized to allow input of various combinations of assays, flows, and other cascade properties. Traditional cascade models have required specification of the enrichment factor, all feed assays, and the product and waste assays of the primary enriched component. The calculation would then produce the numbers of stages in the enriching and stripping sections and the remaining assays in waste and product streams. In cases where the enrichment factor or feed assays were not known, analysis was difficult or impossible. However, if other quantities are known (e.g., additional assays in waste or product streams), a reliable calculation is still possible with the new code, but such nonstandard input may introduce additional numerical difficulties into the calculation. Thus, the minimum input requirements for a stable solution are discussed, and a sample problem with a non-unique solution is described. Both heuristic and mathematically required guidelines are given to assist the application of cascade modeling to situations involving such non-standard input. As a result, this work provides both a calculational tool and specific guidance for evaluation of enrichment cascades in which traditional input data are either flawed or unknown. It is useful for cases involving minor isotopes, especially if the minor isotope assays are desired (or required) to be
Generalized charge-screening in relativistic ThomasFermi model
Akbari-Moghanjoughi, M.
2014-10-15
In this paper, we study the charge shielding within the relativistic Thomas-Fermi model for a wide range of electron number-densities and the atomic-number of screened ions. A generalized energy-density relation is obtained using the force-balance equation and taking into account the Chandrasekhar's relativistic electron degeneracy pressure. By numerically solving a second-order nonlinear differential equation, the Thomas-Fermi screening length is investigated, and the results are compared for three distinct regimes of the solid-density, warm-dense-matter, and white-dwarfs (WDs). It is revealed that our nonlinear screening theory is compatible with the exponentially decaying Thomas-Fermi-type shielding predicted by the linear response theory. Moreover, the variation of relative Thomas-Fermi screening length shows that extremely dense quantum electron fluids are relatively poor charge shielders. Calculation of the total number of screening electrons around a nucleus shows that there is a position of maximum number of screening localized electrons around the screened nucleus, which moves closer to the point-like nucleus by increase in the plasma number density but is unaffected due to increase in the atomic-number value. It is discovered that the total number of screening electrons, (N{sub s}?r{sub TF}{sup 3}/r{sub d}{sup 3} where r{sub TF} and r{sub d} are the Thomas-Fermi and interparticle distance, respectively) has a distinct limit for extremely dense plasmas such as WD-cores and neutron star crusts, which is unique for all given values of the atomic-number. This is equal to saying that in an ultrarelativistic degeneracy limit of electron-ion plasma, the screening length couples with the system dimensionality and the plasma becomes spherically self-similar. Current analysis can provide useful information on the effects of relativistic correction to the charge screening for a wide range of plasma density, such as the inertial-confined plasmas and compact stellar
Model for Energy Supply System Alternatives and their General...
Resource Type: Softwaremodeling tools Website: www-tc.iaea.orgtcwebabouttcstrategyThematicpdfpresentationsener References: Overview of IAEA PESS Models 1 "MESSAGE...
Simple ocean carbon cycle models
Caldeira, K.; Hoffert, M.I.; Siegenthaler, U.
1994-02-01
Simple ocean carbon cycle models can be used to calculate the rate at which the oceans are likely to absorb CO{sub 2} from the atmosphere. For problems involving steady-state ocean circulation, well calibrated ocean models produce results that are very similar to results obtained using general circulation models. Hence, simple ocean carbon cycle models may be appropriate for use in studies in which the time or expense of running large scale general circulation models would be prohibitive. Simple ocean models have the advantage of being based on a small number of explicit assumptions. The simplicity of these ocean models facilitates the understanding of model results.
Stochastic resonance in a generalized Von Foerster population growth model
Lumi, N.; Mankin, R.
2014-11-12
The stochastic dynamics of a population growth model, similar to the Von Foerster model for human population, is studied. The influence of fluctuating environment on the carrying capacity is modeled as a multiplicative dichotomous noise. It is established that an interplay between nonlinearity and environmental fluctuations can cause single unidirectional discontinuous transitions of the mean population size versus the noise amplitude, i.e., an increase of noise amplitude can induce a jump from a state with a moderate number of individuals to that with a very large number, while by decreasing the noise amplitude an opposite transition cannot be effected. An analytical expression of the mean escape time for such transitions is found. Particularly, it is shown that the mean transition time exhibits a strong minimum at intermediate values of noise correlation time, i.e., the phenomenon of stochastic resonance occurs. Applications of the results in ecology are also discussed.
System Advisor Model, SAM 2014.1.14: General Description
Blair, N.; Dobos, A. P.; Freeman, J.; Neises, T.; Wagner, M.; Ferguson, T.; Gilman, P.; Janzou, S.
2014-02-01
This document describes the capabilities of the U.S. Department of Energy and National Renewable Energy Laboratory's System Advisor Model (SAM), Version 2013.9.20, released on September 9, 2013. SAM is a computer model that calculates performance and financial metrics of renewable energy systems. Project developers, policy makers, equipment manufacturers, and researchers use graphs and tables of SAM results in the process of evaluating financial, technology, and incentive options for renewable energy projects. SAM simulates the performance of photovoltaic, concentrating solar power, solar water heating, wind, geothermal, biomass, and conventional power systems. The financial model can represent financial structures for projects that either buy and sell electricity at retail rates (residential and commercial) or sell electricity at a price determined in a power purchase agreement (utility). SAM's advanced simulation options facilitate parametric and sensitivity analyses, and statistical analysis capabilities are available for Monte Carlo simulation and weather variability (P50/P90) studies. SAM can also read input variables from Microsoft Excel worksheets. For software developers, the SAM software development kit (SDK) makes it possible to use SAM simulation modules in their applications written in C/C++, C#, Java, Python, and MATLAB. NREL provides both SAM and the SDK as free downloads at http://sam.nrel.gov. Technical support and more information about the software are available on the website.
System Advisor Model, SAM 2011.12.2: General Description
Gilman, P.; Dobos, A.
2012-02-01
This document describes the capabilities of the U.S. Department of Energy and National Renewable Energy Laboratory's System Advisor Model (SAM), Version 2011.12.2, released on December 2, 2011. SAM is software that models the cost and performance of renewable energy systems. Project developers, policy makers, equipment manufacturers, and researchers use graphs and tables of SAM results in the process of evaluating financial, technology, and incentive options for renewable energy projects. SAM simulates the performance of solar, wind, geothermal, biomass, and conventional power systems. The financial model can represent financing structures for projects that either buy and sell electricity at retail rates (residential and commercial) or sell electricity at a price determined in a power purchase agreement (utility). Advanced analysis options facilitate parametric, sensitivity, and statistical analyses, and allow for interfacing SAM with Microsoft Excel or with other computer programs. SAM is available as a free download at http://sam.nrel.gov. Technical support and more information about the software are available on the website.
Global warming and changes in ocean circulation
Duffy, P.B.; Caldeira, K.C.
1998-02-01
This final report provides an overview of the goals and accomplishments of this project. Modeling and observational work has raised the possibility that global warming may cause changes in the circulation of the ocean. If such changes would occur they could have important climatic consequences. The first technical goal of this project was to investigate some of these possible changes in ocean circulation in a quantitative way, using a state-of -the-art numerical model of the ocean. Another goal was to develop our ocean model, a detailed three-dimensional numerical model of the ocean circulation and ocean carbon cycles. A major non-technical goal was to establish LLNL as a center of excellence in modelling the ocean circulation and carbon cycle.
Unified Einstein-Virasoro Master Equation in the General Non-Linear Sigma Model
Boer, J. de; Halpern, M.B.
1996-06-05
The Virasoro master equation (VME) describes the general affine-Virasoro construction $T=L^abJ_aJ_b+iD^a \\dif J_a$ in the operator algebra of the WZW model, where $L^ab$ is the inverse inertia tensor and $D^a $ is the improvement vector. In this paper, we generalize this construction to find the general (one-loop) Virasoro construction in the operator algebra of the general non-linear sigma model. The result is a unified Einstein-Virasoro master equation which couples the spacetime spin-two field $L^ab$ to the background fields of the sigma model. For a particular solution $L_G^ab$, the unified system reduces to the canonical stress tensors and conventional Einstein equations of the sigma model, and the system reduces to the general affine-Virasoro construction and the VME when the sigma model is taken to be the WZW action. More generally, the unified system describes a space of conformal field theories which is presumably much larger than the sum of the general affine-Virasoro construction and the sigma model with its canonical stress tensors. We also discuss a number of algebraic and geometrical properties of the system, including its relation to an unsolved problem in the theory of $G$-structures on manifolds with torsion.
Fuel-efficient cruise performance model for general aviation piston engine airplanes
Parkinson, R.C.H.
1982-01-01
The uses and limitations of typical Pilot Operating Handbook cruise performance data, for constructing cruise performance models suitable for maximizing specific range, are first examined. These data are found to be inadequate for constructing such models. A new model of General Aviation piston-prop airplane cruise performance is then developed. This model consists of two subsystem models: the airframe-propeller-atmosphere subsystem model; and the engine-atmosphere subsystem model. The new model facilitates maximizing specific range; and by virtue of its simplicity and low volume data storage requirements, appears suitable for airborne microprocessor implementation.
Miller, A.J. )
1992-02-15
Midlatitude ocean-atmosphere interactions are studied in simulations from a simplified coupled model that includes synoptic-scale atmospheric variability, ocean current advection of sea surface temperature (SST), and air-sea heat exchange. Although theoretical dynamical ([open quotes]identical twin[close quotes]) predictions using this model have shown that the SST anomalies in this model indeed influence the atmosphere, it is found here that standard cross-correlation and empirical orthogonal function analyses of monthly mean model output yield the standard result, familiar from observational studies, that the atmosphere forces the ocean with little or no feedback. Therefore, these analyses are inconclusive and leave open the question of whether anomalous SST is influencing the atmosphere. In contrast, the authors find that compositing strong warm events of model SST is a useful indicator of ocean forcing the atmosphere. The authors present additional evidence for oceanic influence on the atmosphere, namely, that ocean current advection appears to enhance the persistence of model SST anomalies through a feedback effect that is absent when only heat flux is allowed to influence SST anomaly evolution. Models with more complete physics must ultimately be used to conclusively demonstrate these results. 26 refs., 27 figs., 5 tabs.
Ehnert, Sabrina; Freude, Thomas; Ihle, Christoph; Mayer, Larissa; Braun, Bianca; Graeser, Jessica; Flesch, Ingo; and others
2015-03-15
Type 2 diabetes mellitus (T2DM) is one of the most frequent metabolic disorders in industrialized countries. Among other complications, T2DM patients have an increased fracture risk and delayed fracture healing. We have demonstrated that supraphysiological glucose and insulin levels inhibit primary human osteoblasts' maturation. We aimed at developing a more physiologically relevant in vitro model to analyze T2DM-mediated osteoblast changes. Therefore, SCP-1-immortalized pre-osteoblasts were differentiated with T2DM or control (non-obese and obese) sera. Between both control groups, no significant changes were observed. Proliferation was significantly increased (1.69-fold), while AP activity and matrix mineralization was significantly reduced in the T2DM group. Expression levels of osteogenic marker genes and transcription factors were altered, e.g. down-regulation of RUNX2 and SP-7 or up-regulation of STAT1, in the T2DM group. Active TGF-β levels were significantly increased (1.46-fold) in T2DM patients' sera. SCP-1 cells treated with these sera showed significantly increased TGF-β signaling (2.47-fold). Signaling inhibition effectively restored osteoblast maturation in the T2DM group. Summarizing our data, SCP-1 cells differentiated in the presence of T2DM patients' serum exhibit reduced osteoblast function. Thus, this model has a high physiological impact, as it can identify circulating factors in T2DM patients' blood that may affect bone function, e.g. TGF-β. - Highlights: • We present here a physiologically relevant in vitro model for diabetic osteopathy. • Blood of T2DM patients contains factors that affect osteoblasts' function. • The model developed here can be used to identify these factors, e.g. TGF-β. • Blocking TGF-β signaling partly rescues the osteoblasts' function in the T2DM group. • The model is useful to demonstrate the role of single factors in diabetic osteopathy.
A General Nonlinear Fluid Model for Reacting Plasma-Neutral Mixtures
Meier, E T; Shumlak, U
2012-04-06
A generalized, computationally tractable fluid model for capturing the effects of neutral particles in plasmas is derived. The model derivation begins with Boltzmann equations for singly charged ions, electrons, and a single neutral species. Electron-impact ionization, radiative recombination, and resonant charge exchange reactions are included. Moments of the reaction collision terms are detailed. Moments of the Boltzmann equations for electron, ion, and neutral species are combined to yield a two-component plasma-neutral fluid model. Separate density, momentum, and energy equations, each including reaction transfer terms, are produced for the plasma and neutral equations. The required closures for the plasma-neutral model are discussed.
Krishna, S.; Shukla, A.; Malik, R.P.
2014-12-15
Using the supersymmetric (SUSY) invariant restrictions on the (anti-)chiral supervariables, we derive the off-shell nilpotent symmetries of the general one (0+1)-dimensional N=2 SUSY quantum mechanical (QM) model which is considered on a (1, 2)-dimensional supermanifold (parametrized by a bosonic variable t and a pair of Grassmannian variables θ and θ-bar with θ{sup 2}=(θ-bar){sup 2}=0,θ(θ-bar)+(θ-bar)θ=0). We provide the geometrical meanings to the two SUSY transformations of our present theory which are valid for any arbitrary type of superpotential. We express the conserved charges and Lagrangian of the theory in terms of the supervariables (that are obtained after the application of SUSY invariant restrictions) and provide the geometrical interpretation for the nilpotency property and SUSY invariance of the Lagrangian for the general N=2 SUSY quantum theory. We also comment on the mathematical interpretation of the above symmetry transformations. - Highlights: • A novel method has been proposed for the derivation of N=2 SUSY transformations. • General N=2 SUSY quantum mechanical (QM) model with a general superpotential, is considered. • The above SUSY QM model is generalized onto a (1, 2)-dimensional supermanifold. • SUSY invariant restrictions are imposed on the (anti-)chiral supervariables. • Geometrical meaning of the nilpotency property is provided.
Change of variables as a method to study general ?-models: Bulk universality
Shcherbina, M.
2014-04-15
We consider ? matrix models with real analytic potentials. Assuming that the corresponding equilibrium density ? has a one-interval support (without loss of generality ? = [?2, 2]), we study the transformation of the correlation functions after the change of variables ?{sub i} ? ?(?{sub i}) with ?(?) chosen from the equation ?{sup ?}(?)?(?(?)) = ?{sub sc}(?), where ?{sub sc}(?) is the standard semicircle density. This gives us the deformed ?-model which has an additional interaction term. Standard transformation with the Gaussian integral allows us to show that the deformed ?-model may be reduced to the standard Gaussian ?-model with a small perturbation n{sup ?1}h(?). This reduces most of the problems of local and global regimes for ?-models to the corresponding problems for the Gaussian ?-model with a small perturbation. In the present paper, we prove the bulk universality of local eigenvalue statistics for both one-cut and multi-cut cases.
Jorgensen, Jorgen A.; Nygren, Donald W.
1983-01-01
A portable air circulating apparatus for use in cooking ovens which is used to create air currents in the oven which transfer heat to cooking foodstuffs to promote more rapid and more uniform cooking or baking, the apparatus including a motor, fan blade and housing of metallic materials selected from a class of heat resistant materials.
Integrated hydrogeological model of the general separations area. Volume 2: groundwater flow model
Flach, G.P.; Harris, M.K.
1997-08-01
This report models the Gordon aquifer, the Gordon confining unit, and the `lower` aquifer zone, `tan clay` confining zone, and `upper` aquifer zone of the Water Table aquifer. The report presents structure-contour and isopach maps of each unit.
A kernel-oriented model for coalition-formation in general environments: Implementation and results
Shehory, O.; Kraus, S.
1996-12-31
In this paper we present a model for coalition formation and payoff distribution in general environments. We focus on a reduced complexity kernel-oriented coalition formation model, and provide a detailed algorithm for the activity of the single rational agent. The model is partitioned into a social level and a strategic level, to distinguish between regulations that must be agreed upon and are forced by agent-designers, and strategies by which each agent acts at will. In addition, we present an implementation of the model and simulation results. From these we conclude that implementing the model for coalition formation among agents increases the benefits of the agents with reasonable time consumption. It also shows that more coalition formations yield more benefits to the agents.
Agarwala, R. [National Institutes of Health, Bethesda, MD (United States); Batzoglou, S. [MIT, Cambridge, MA (United States); Dancik, V. [Univ. of Southern California, Los Angeles, CA (United States)] [and others
1997-06-01
We consider the problem of determining the three-dimensional folding of a protein given its one-dimensional amino acid sequence. We use the HP model for protein folding proposed by Dill, which models protein as a chain of amino acid residues that are either hydrophobic or polar, and hydrophobic interactions are the dominant initial driving force for the protein folding. Hart and Istrail gave approximation algorithms for folding proteins on the cubic lattice under HP model. In this paper, we examine the choice of a lattice by considering its algorithmic and geometric implications and argue that triangular lattice is a more reasonable choice. We present a set of folding rules for a triangular lattice and analyze the approximation ratio which they achieve. In addition, we introduce a generalization of the HP model to account for residues having different levels of hydrophobicity. After describing the biological foundation for this generalization, we show that in the new model we are able to achieve similar constant factor approximation guarantees on the triangular lattice as were achieved in the standard HP model. While the structures derived from our folding rules are probably still far from biological reality, we hope that having a set of folding rules with different properties will yield more interesting folds when combined.
Gao Yajun
2008-08-15
A previously established Hauser-Ernst-type extended double-complex linear system is slightly modified and used to develop an inverse scattering method for the stationary axisymmetric general symplectic gravity model. The reduction procedures in this inverse scattering method are found to be fairly simple, which makes the inverse scattering method applied fine and effective. As an application, a concrete family of soliton double solutions for the considered theory is obtained.
Allu, Srikanth; Velamur Asokan, Badri; Shelton, William A; Philip, Bobby; Pannala, Sreekanth
2014-01-01
A generalized three dimensional computational model based on unied formulation of electrode- electrolyte-electrode system of a electric double layer supercapacitor has been developed. The model accounts for charge transport across the solid-liquid system. This formulation based on volume averaging process is a widely used concept for the multiphase ow equations ([28] [36]) and is analogous to porous media theory typically employed for electrochemical systems [22] [39] [12]. This formulation is extended to the electrochemical equations for a supercapacitor in a consistent fashion, which allows for a single-domain approach with no need for explicit interfacial boundary conditions as previously employed ([38]). In this model it is easy to introduce the spatio-temporal variations, anisotropies of physical properties and it is also conducive for introducing any upscaled parameters from lower length{scale simulations and experiments. Due to the irregular geometric congurations including porous electrode, the charge transport and subsequent performance characteristics of the super-capacitor can be easily captured in higher dimensions. A generalized model of this nature also provides insight into the applicability of 1D models ([38]) and where multidimensional eects need to be considered. In addition, simple sensitivity analysis on key input parameters is performed in order to ascertain the dependence of the charge and discharge processes on these parameters. Finally, we demonstarted how this new formulation can be applied to non-planar supercapacitors
The Transient Circulation Response to Radiative Forcings and Sea Surface Warming
Staten, Paul; Reichler, Thomas; Lu, Jian
2014-08-27
Tropospheric circulation shifts have strong potential to impact surface climate. But the magnitude of these shifts in a changing climate, and the attending regional hydrological changes, are difficult to project. Part of this difficulty arises from our lack of understanding of the physical mechanisms behind the circulation shifts themselves. In order to better delineate circulation shifts and their respective causes, we decompose the circulation response into (1) the "direct" response to radiative forcings themselves, and (2) the "indirect" response to changing sea surface temperatures. Using ensembles of 90-day climate model simulations with immediate switch-on forcings, including perturbed greenhouse gas concentrations, stratospheric ozone concentrations, and sea surface temperatures, we document the direct and indirect transient responses of the zonal mean general circulation, and investigate the roles of previously proposed mechanisms in shifting the midlatitude jet. We find that both the direct and indirect wind responses often begin in the lower stratosphere. Changes in midlatitude eddies are ubiquitous and synchronous with the midlatitude zonal wind response. Shifts in the critical latitude of wave absorption on either flank of the jet are not indicted as primary factors for the poleward shifting jet, although we see some evidence for increasing equatorward wave reflection over the southern hemisphere in response to sea surface warming. Mechanisms for the northern hemisphere jet shift are less clear.
Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model
Weng, Ensheng; Luo, Yiqi; Wang, Weile; Wang, Han; Hayes, Daniel J; McGuire, A. David; Hastings, Alan; Schimel, David
2012-01-01
Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U {center_dot} {tau}{sub E} {center_dot} {lambda}{lambda} + s {tau} 1, where U is ecosystem carbon influx, {tau}{sub E} is ecosystem carbon residence time, and {tau}{sub 1} is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval ({lambda}) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45{sup o} N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.
McManamay, Ryan A
2014-01-01
Despite the ubiquitous existence of dams within riverscapes, much of our knowledge about dams and their environmental effects remains context-specific. Hydrology, more than any other environmental variable, has been studied in great detail with regard to dam regulation. While much progress has been made in generalizing the hydrologic effects of regulation by large dams, many aspects of hydrology show site-specific fidelity to dam operations, small dams (including diversions), and regional hydrologic regimes. A statistical modeling framework is presented to quantify and generalize hydrologic responses to varying degrees of dam regulation. Specifically, the objectives were to 1) compare the effects of local versus cumulative dam regulation, 2) determine the importance of different regional hydrologic regimes in influencing hydrologic responses to dams, and 3) evaluate how different regulation contexts lead to error in predicting hydrologic responses to dams. Overall, model performance was poor in quantifying the magnitude of hydrologic responses, but performance was sufficient in classifying hydrologic responses as negative or positive. Responses of some hydrologic indices to dam regulation were highly dependent upon hydrologic class membership and the purpose of the dam. The opposing coefficients between local and cumulative-dam predictors suggested that hydrologic responses to cumulative dam regulation are complex, and predicting the hydrology downstream of individual dams, as opposed to multiple dams, may be more easy accomplished using statistical approaches. Results also suggested that particular contexts, including multipurpose dams, high cumulative regulation by multiple dams, diversions, close proximity to dams, and certain hydrologic classes are all sources of increased error when predicting hydrologic responses to dams. Statistical models, such as the ones presented herein, show promise in their ability to model the effects of dam regulation effects at
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6Be General Table The General Table for 6Be is subdivided into the following categories: Cluster Model Model Calculations...
A Generalized Fokker-Planck Model for Transport of Collimated Beams
Prinja, Anil K.; Pomraning, G.C.
2001-03-15
A generalized Fokker-Planck (GFP) model is introduced for application to the problem of the angular spreading of a broad beam of charged particles. This approach extends the classic Fokker-Planck (FP) approximation of the scattering operator to instances when the differential scattering cross section is not sufficiently forward peaked for the strict FP representation to be valid. Our previously developed (1 - {mu}){sup n}-moments method is used to construct a truncated hierarchy of moment equations from the GFP and transport equations. For slab thicknesses that are small compared to the transport mean-free-path, the scalar flux is explicitly represented as a Taylor expansion in the depth variable for different truncation orders and for different orders of the generalized Fokker-Planck expansion. Numerical results indicate that the GFP method is a viable method for dealing with larger scattering angles than are possible with the classic FP approximation.
Testing the (generalized) Chaplygin gas model with the lookback time-redshift data
Li, Zhengxiang; Wu, Puxun; Yu, Hongwei E-mail: wpx0227@gmail.com
2009-09-01
The Chaplygin gas (CG) and the generalized Chaplygin gas (GCG) models, proposed as candidates of the unified dark matter-dark energy (UDME), are tested with the look-back time (LT) redshift data. We find that the LT data only give a very weak constraint on the model parameter. However, by combing the LT with the baryonic acoustic oscillation peak, we obtain, at the 95.4% confidence level, 0.68 ≤ A{sub c} ≤ 0.82 and 0.59 ≤ h ≤ 0.65 for the CG model , and 0.67 ≤ A{sub s} ≤ 0.89 and −0.29 ≤ α ≤ 0.61 for the GCG model. This shows that both the CG and the GCG are viable as a candidate of UDME. Within the GCG model, we also find that the Chaplygin gas model (α = 1) is ruled out by these data at the 99.7% confidence level.
Barnett, T.P.
1998-11-30
The objectives of this report are to determine the structure of oceanic natural variability at time scales of decades to centuries, characterize the physical mechanisms responsible for the variability; determine the relative importance of heat, fresh water, and moment fluxes on the variability; determine the predictability of the variability on these times scales. (B204)
Computable General Equilibrium Model Fiscal Year 2013 Capability Development Report - April 2014
Edwards, Brian Keith; Rivera, Michael K.; Boero, Riccardo
2014-04-01
This report documents progress made on continued developments of the National Infrastructure Simulation and Analysis Center (NISAC) Computable General Equilibrium Model (NCGEM), developed in fiscal year 2012. In fiscal year 2013, NISAC the treatment of the labor market and tests performed with the model to examine the properties of the solutions computed by the model. To examine these, developers conducted a series of 20 simulations for 20 U.S. States. Each of these simulations compared an economic baseline simulation with an alternative simulation that assumed a 20-percent reduction in overall factor productivity in the manufacturing industries of each State. Differences in the simulation results between the baseline and alternative simulations capture the economic impact of the reduction in factor productivity. While not every State is affected in precisely the same way, the reduction in manufacturing industry productivity negatively affects the manufacturing industries in each State to an extent proportional to the reduction in overall factor productivity. Moreover, overall economic activity decreases when manufacturing sector productivity is reduced. Developers ran two additional simulations: (1) a version of the model for the State of Michigan, with manufacturing divided into two sub-industries (automobile and other vehicle manufacturing as one sub-industry and the rest of manufacturing as the other subindustry); and (2) a version of the model for the United States, divided into 30 industries. NISAC conducted these simulations to illustrate the flexibility of industry definitions in NCGEM and to examine the simulation properties of in more detail.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
5 General Tables The General Table for 5H is subdivided into the following categories: Cluster Model Hypernuclei Model Calculations Photodisintegration Pions The General Table for...
Wakamatsu, M.; Tsujimoto, H. [Department of Physics, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)
2005-04-01
The theoretical predictions are given for the forward limit of the unpolarized spin-flip isovector generalized parton distribution function (E{sup u}-E{sup d})(x,{xi},t) within the framework of the chiral quark soliton model, with full inclusion of the polarization of Dirac sea quarks. We observe that [(H{sup u}-H{sup d})+(E{sup u}-E{sup d})](x,0,0) has a sharp peak around x=0, which we interpret as a signal of the importance of the pionic qq excitation with large spatial extension in the transverse direction. Another interesting indication given by the predicted distribution in combination with Ji's angular momentum sum rule is that the d quark carries more angular momentum than the u quark in the proton, which may have some relation with the physics of the violation of the Gottfried sum rule.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Be General Table The General Table for 7Be is subdivided into the following categories: Reviews Experimental Work Shell Model Cluster Model Other Theoretical Work Model...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
General Table The General Table for 10He is subdivided into the following categories: Theoretical Shell Model Cluster Model Other Models Special States Electromagnetic Transitions...
TROPICAL METEOROLOGY & Climate: Hadley Circulation
Lu, Jian; Vecchi, Gabriel A.
2015-01-30
The Hadley circulation, a prominent circulation feature characterized by rising air near the Equator and sinking air in the subtropics, defines the position of dry subtropical areas and is a fundamental regulator of the earth’s energy and momentum budgets. The character of the Hadley circulation, and its related precipitation regimes, exhibits variation and change in response to both climate variability and radiative forcing changes. The strength and position of the Hadley circulation change from year to year paced by El Niño and La Niña events. Over the last few decades of the twentieth century, the Hadley cell has expanded poleward in both hemispheres, with changes in atmospheric composition (including stratospheric ozone depletion and greenhouse gas increases) thought to have contributed to its expansion. This article introduces the basic phenomenology and driving mechanism of the Hadley circulation and discusses its variations under both natural and anthropogenic climate forcings.
The Role of Circulation Features on Black Carbon Transport into...
Office of Scientific and Technical Information (OSTI)
Carbon Transport into the Arctic in the Community Atmosphere Model Version 5 (CAM5) Citation Details In-Document Search Title: The Role of Circulation Features on Black Carbon ...
A coupled theory of tropical climatology: Warm pool, cold tongue, and Walker circulation
Zhengyu Liu; Boyin Huang
1997-07-01
Based on results from analytic and general circulation models, the authors propose a theory for the coupled warm pool, cold tongue, and Walker circulation system. The intensity of the coupled system is determined by the coupling strength, the local equilibrium time, and latitudinal differential heating. Most importantly, this intensity is strongly regulated in the coupled system, with a saturation level that can be reached at a modest coupling strength. The saturation west-east sea surface temperature difference (and the associated Walker circulation) corresponds to about one-quarter of the latitudinal differential equilibrium temperature. This regulation is caused primarily by the decoupling of the SST gradient from a strong ocean current. The author`s estimate suggests that the present Pacific is near the saturation state. Furthermore, the much weaker Walker circulation system in the Atlantic Ocean is interpreted as being the result of the influence of the adjacent land, which is able to extend into the entire Atlantic to change the zonal distribution of the trade wind. The theory is also applied to understand the tropical climatology in coupled GCM simulations, in the Last Glacial Maximum climate, and in the global warming climate, as well as in the regulation of the tropical sea surface temperature. 41 refs., 15 figs.
Yock, Adam D. Kudchadker, Rajat J.; Rao, Arvind; Dong, Lei; Beadle, Beth M.; Garden, Adam S.; Court, Laurence E.
2014-05-15
Purpose: The purpose of this work was to develop and evaluate the accuracy of several predictive models of variation in tumor volume throughout the course of radiation therapy. Methods: Nineteen patients with oropharyngeal cancers were imaged daily with CT-on-rails for image-guided alignment per an institutional protocol. The daily volumes of 35 tumors in these 19 patients were determined and used to generate (1) a linear model in which tumor volume changed at a constant rate, (2) a general linear model that utilized the power fit relationship between the daily and initial tumor volumes, and (3) a functional general linear model that identified and exploited the primary modes of variation between time series describing the changing tumor volumes. Primary and nodal tumor volumes were examined separately. The accuracy of these models in predicting daily tumor volumes were compared with those of static and linear reference models using leave-one-out cross-validation. Results: In predicting the daily volume of primary tumors, the general linear model and the functional general linear model were more accurate than the static reference model by 9.9% (range: −11.6%–23.8%) and 14.6% (range: −7.3%–27.5%), respectively, and were more accurate than the linear reference model by 14.2% (range: −6.8%–40.3%) and 13.1% (range: −1.5%–52.5%), respectively. In predicting the daily volume of nodal tumors, only the 14.4% (range: −11.1%–20.5%) improvement in accuracy of the functional general linear model compared to the static reference model was statistically significant. Conclusions: A general linear model and a functional general linear model trained on data from a small population of patients can predict the primary tumor volume throughout the course of radiation therapy with greater accuracy than standard reference models. These more accurate models may increase the prognostic value of information about the tumor garnered from pretreatment computed tomography
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He General Table The General Table for 9He is subdivided into the following categories: Shell Model Other Model Calculations Theoretical
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He General Table The General Table for 5He is subdivided into the following categories: Ground State Properties Theoretical Special States Model Discussions Shell Model Cluster...
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H General Table The General Table for 5H is subdivided into the following categories: Cluster Model Hypernuclei Model Calculations Photodisintegration Pions...
Keane, R.E.; Long, D.G.; Menakis, J.P.; Hann, W.J.; Bevins, C.D.
1996-10-01
The paper details the landscape succession model developed for the coarse-scale assessment called CRBSUM (Columbia River Basin SUccession Model) and presents some general results of the application of this model to the entire basin. CRBSUM was used to predict future landscape characteristics to evaluate management alternatives for both mid-and coarse-scale efforts. A test and sensitivity analysis of CRBSUM is also presented. This paper was written as a users guide for those who wish to run the model and interprete results, and its was also written as documentation for some results of the Interior Columbia River Basin simulation effort.
Two-phase flow stability structure in a natural circulation system
Zhou, Zhiwei
1995-09-01
The present study reports a numerical analysis of two-phase flow stability structures in a natural circulation system with two parallel, heated channels. The numerical model is derived, based on the Galerkin moving nodal method. This analysis is related to some design options applicable to integral heating reactors with a slightly-boiling operation mode, and is also of general interest to similar facilities. The options include: (1) Symmetric heating and throttling; (2) Asymmetric heating and symmetric throttling; (3) Asymmetric heating and throttling. The oscillation modes for these variants are discussed. Comparisons with the data from the INET two-phase flow stability experiment have qualitatively validated the present analysis.
Trampedach, Regner; Asplund, Martin; Collet, Remo; Nordlund, Ake
2013-05-20
Present grids of stellar atmosphere models are the workhorses in interpreting stellar observations and determining their fundamental parameters. These models rely on greatly simplified models of convection, however, lending less predictive power to such models of late-type stars. We present a grid of improved and more reliable stellar atmosphere models of late-type stars, based on deep, three-dimensional (3D), convective, stellar atmosphere simulations. This grid is to be used in general for interpreting observations and improving stellar and asteroseismic modeling. We solve the Navier Stokes equations in 3D and concurrent with the radiative transfer equation, for a range of atmospheric parameters, covering most of stellar evolution with convection at the surface. We emphasize the use of the best available atomic physics for quantitative predictions and comparisons with observations. We present granulation size, convective expansion of the acoustic cavity, and asymptotic adiabat as functions of atmospheric parameters.
Circulation in gas-slurry column reactors
Clark, N.; Kuhlman, J.; Celik, I.; Gross, R.; Nebiolo, E.; Wang, Yi-Zun.
1990-08-15
Circulation in bubble columns, such as those used in fischer-tropsch synthesis, detracts from their performance in that gas is carried on average more rapidly through the column, and the residence time distribution of the gas in the column is widened. Both of these factors influence mass-transfer operations in bubble columns. Circulation prediction and measurement has been undertaken using probes, one-dimensional models, laser Doppler velocimetry, and numerical modeling. Local void fraction was measured using resistance probes and a newly developed approach to determining air/water threshold voltage for the probe. A tall column of eight inch diameter was constructed of Plexiglas and the distributor plate was manufactured to distribute air evenly through the base of the column. Data were gathered throughout the volume at three different gas throughputs. Bubble velocities proved difficult to measure using twin probes with cross-correlation because of radial bubble movement. A series of three-dimensional mean and RMS bubble and liquid velocity measurements were also obtained for a turbulent flow in a laboratory model of a bubble column. These measurements have been made using a three-component laser Doppler velocimeter (LDV), to determine velocity distributions non-intrusively. Finally, the gas-liquid flow inside a vertically situated circular isothermal column reactor was simulated numerically. 74 refs., 170 figs., 5 tabs.
A general model of resource production and exchange in systems of interdependent specialists.
Conrad, Stephen Hamilton; Finley, Patrick D.; Beyeler, Walter Eugene; Brown, Theresa Jean; Glass, Robert John, Jr.; Breen, Peter; Kuypers, Marshall; Norton, Matthew David; Quach, Tu-Thach; Antognoli, Matthew; Mitchell, Michael David
2011-11-01
Infrastructures are networks of dynamically interacting systems designed for the flow of information, energy, and materials. Under certain circumstances, disturbances from a targeted attack or natural disasters can cause cascading failures within and between infrastructures that result in significant service losses and long recovery times. Reliable interdependency models that can capture such multi-network cascading do not exist. The research reported here has extended Sandia's infrastructure modeling capabilities by: (1) addressing interdependencies among networks, (2) incorporating adaptive behavioral models into the network models, and (3) providing mechanisms for evaluating vulnerability to targeted attack and unforeseen disruptions. We have applied these capabilities to evaluate the robustness of various systems, and to identify factors that control the scale and duration of disruption. This capability lays the foundation for developing advanced system security solutions that encompass both external shocks and internal dynamics.
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Table for 10He is subdivided into the following categories: Theoretical Shell Model Cluster Model Other Models Special States Electromagnetic Transitions The General Table for...
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The General Table for 9Li is subdivided into the following categories: Shell Model Cluster Model Theoretical Ground State Properties Special States Other Model Calculations...
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Be General Tables The General Table for 8Be is subdivided into the following categories: Reviews Ground State Properties Shell Model Cluster Model Other Models Photodisintegration Fission and Fusion Astrophysical b-decay Hypernuclei
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B General Table The General Table for 9B is subdivided into the following categories: Shell Model Cluster Model Theoretical Other Model Calculations Complex Reactions Beta-Decay Pions Light-ion and Neutron Induced Reactions Hypernuclei
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C General Table The General Table for 9C is subdivided into the following categories: Shell Model Cluster Model Other Models Theoretical Beta-Decay Light-ion and Neutron Induced Reactions Astrophysical
Agarwala, R. [National Institutes of Health, Bethesda, MD (United States); Batzoglou, S. [MIT Lab. for Computer Science, Cambridge, MA (United States); Dancik, V. [Univ. of Southern California, Los Angeles, CA (United States)] [and others
1997-12-01
A long standing problem in molecular biology is to determine the three-dimensional structure of a protein, given its amino acid sequence. A variety of simplifying models have been proposed abstracting only the {open_quotes}essential physical properties{close_quotes} of real proteins. In these models, the three dimensional space is often represented by a lattice. Residues which are adjacent in the primary sequence (i.e. covalently linked) must be placed at adjacent points in the lattice. A conformation of a protein is simply a self-avoiding walk along the lattice. The protein folding problem STRING-FOLD is that of finding a conformation of the protein sequence on the lattice such that the overall energy is minimized, for some reasonable definition of energy. This formulation leaves open the choices of a lattice and an energy function. Once these choices are made, one may then address the algorithmic complexity of optimizing the energy function for the lattice. For a variety of such simple models, this minimization problem is in fact NP-hard. In this paper, we consider the Hydrophobic-Polar (HP) Model introduced by Dill. The HP model abstracts the problem by grouping the 20 amino acids into two classes: hydrophobic (or non-polar) residues and hydrophilic (or polar) residues. For concreteness, we will take our input to be a string from (H,P){sup +}, where P represents polar residues, and H represents hydrophobic residues. Dill et.al. survey the literature analyzing this model. 8 refs., 2 figs., 1 tab.
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He General Table The General Table for 7He is subdivided into the following categories: Experimental Theoretical Model Calculations Hypernuclei and Mesons Pions
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He General Table The General Table for 6He is subdivided into the following categories: Ground State Properties Theoretical Special States Shell Model Cluster and alpha-particle...
LBE Natural Circulation Fluid Dynamics Validation Project
Voit, Regan; Prince, Robert; Cacuci, Dan G.
2015-12-20
Conceptual design of a scaled Natural Circulation Experimental Facility (NCEF) for providing data in support of validating reactor design codes.
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The Research Library provides a large collection of print and electronic books, journals, reports, conference proceedings and many audiovisual materials. Research Library...
Weyermann, D.L.; Fight, R.D.; Garrett, F.D.
1991-08-01
This paper instructs resource analysts on using the southeast Alaska multiresource model (SAMM). SAMM is an interactive microcomputer program that allows users to explore relations among several resources in southeast Alaska (timber, anadromous fish, deer, and hydrology) and the effects of timber management activities (logging, thinning, and road building) on those relations and resources. This guide assists users in installing SAMM on a microcomputer, developing input data files, making simulation runs, and strong output data for external analysis and graphic display.
Generalization of the ERIT Principle and Method
Ruggiero,A.
2008-02-01
The paper describes the generalization of the method to produce secondary particles with a low-energy and low-intensity primary beam circulating in a Storage Ring with the Emittance-Recovery by Internal-Target (ERIT).
Generalization of the ERIT principle and method.
Ruggiero,A.G.
2007-11-04
The paper describes the generalization of the method to produce secondary particles with a low-energy and low-intensity primary beam circulating in a Storage Ring with the Emittance-Recovery by Internal-Target (ERIT).
Matrix-free constructions of circulant and block circulant preconditioners
Yang, Chao; Ng, Esmond G.; Penczek, Pawel A.
2001-12-01
A framework for constructing circulant and block circulant preconditioners (C) for a symmetric linear system Ax=b arising from certain signal and image processing applications is presented in this paper. The proposed scheme does not make explicit use of matrix elements of A. It is ideal for applications in which A only exists in the form of a matrix vector multiplication routine, and in which the process of extracting matrix elements of A is costly. The proposed algorithm takes advantage of the fact that for many linear systems arising from signal or image processing applications, eigenvectors of A can be well represented by a small number of Fourier modes. Therefore, the construction of C can be carried out in the frequency domain by carefully choosing its eigenvalues so that the condition number of C{sup T} AC can be reduced significantly. We illustrate how to construct the spectrum of C in a way such that the smallest eigenvalues of C{sup T} AC overlaps with those of A extremely well while the largest eigenvalues of C{sup T} AC are smaller than those of A by several orders of magnitude. Numerical examples are provided to demonstrate the effectiveness of the preconditioner on accelerating the solution of linear systems arising from image reconstruction application.
Circulation in Enewetak Atoll lagoon
Atkinson, M.; Smith, S.V.; Stroup, E.D.
1981-11-01
Currents at Enewetak Atoll, Marshall Islands, were measured on the reef margins, in the channels, and in the lagoon. Lagoon circulation is dominated by wind-driven downwind surface flow and an upwind middepth return flow. This wind-driven flow has the characteristics of an Ekman spiral in an enclosed sea. Lagoon flushing is accomplished primarily by surf-driven water input over the windward (eastern) reefs and southerly drift out the South Channel. Mean water residence time is 1 month, while water entering the northern portion of the atoll takes about 4 months to exit.
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He General Tables The General Table for 8He is subdivided into the following categories: Reviews Ground-state Properties Shell Model Cluster Model Other Theoretical Work Elastic and Inelastic Scattering b-decay
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Li General Table The General Table for 6Li is subdivided into the following categories: Ground State Properties of 6Li Special States Theoretical Shell Model Cluster Models Complex...
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subdivided into the following categories: Reviews Ground-State Properties Shell Model Cluster Model Other Theoretical Work These General Tables correspond to "Energy Levels of...
Lu, Jian; Sun, Lantao; Wu, Yutian; Chen, Gang
2013-11-21
The atmospheric circulation response to the global warming-like tropical upper tropospheric heating is revisited using a dry atmospheric general circulation model (AGCM) in light of a new diagnostics based on the concept of finite-amplitude wave activity (FAWA) on equivalent latitude. For a given tropical heating profile, the linear Wentzel-Kramers-Brillouin (WKB) wave refraction analysis sometimes gives a very different and even opposite prediction of the eddy momentum flux response to that of the actual full model simulation, exposing the limitation of the traditional linear approach in understanding the full dynamics of the atmospheric response under global warming. The implementation of the FAWA diagnostics reveals that in response to the upper tropospheric heating, effective diffusivity, a measure of the mixing efficiency, increases and advances upward and poleward in the subtropics and the resultant enhancement and the poleward encroachment of eddy potential vorticity mixing leads to a poleward displaced potential vorticity (PV) gradient peak in the upper troposphere. The anomalous eddy PV flux, in balance with the PV dissipation, gives rise to a poleward shift in the eddy-driven jet and eddy-driven mean meridional circulation. Sensitivity experiments show that these irreversible dissipation processes in the upper troposphere are robust, regardless of the width of the tropical heating.
Carderock Circulating Water Channel | Open Energy Information
Features The Circulating Water Channel is a vertical plane, open to the atmosphere test section with a free surface in a closed recirculating water circuit, variable speed,...
Circulating system simplifies dry scrubbing
Morrison, S.Q.; Jorgensen, C.
1995-10-01
This article describes a circulating dry scrubber, based on fluid-bed absorption process, which demonstrates high SO{sub 2} removal with minimal O and M requirements. Unlike other dry scrubbers, this one involves dry reagent and results in dry products. Before construction can begin on a new coal-fired plant, a rigorous set of permit requirements must be satisfied. When the Roanoke Valley Energy Facility, Weldon, NC, began the permitting process for their proposed 44-MW pulverized-coal (p-c)-fired Unit 2, the facility permit limited not only SO{sub 2} emissions (0.187 lb SO{sub 2}/million Btu) but also the removal efficiency of the flue-gas desulfurization process (93%) and the maximum amount of sulfur in the coal (1.6%).
Validation of the RRTM Shortwave Radiation Model and Comparison to GCM Shortwave Models
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Validation of the RRTM Shortwave Radiation Model and Comparison to GCM Shortwave Models M. J. Iacono, E. J. Mlawer, and S. A. Clough Atmospheric and Environmental Research, Inc. Lexington, Massachusetts Introduction An important step toward improving radiative transfer codes in general circulation models (GCMs) is to thoroughly evaluate them either by comparison to measurements directly or by comparing them to other data-validated radiation models. The Rapid Radiative Transfer Model (RRTM)
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Downhole material injector for lost circulation control
Glowka, David A.
1994-01-01
Apparatus and method for simultaneously and separately emplacing two streams of different materials through a drillstring in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drillstring at the desired downhole location and harden only after mixing for control of a lost circulation zone.
Downhole material injector for lost circulation control
Glowka, D.A.
1994-09-06
Apparatus and method are disclosed for simultaneously and separately emplacing two streams of different materials through a drill string in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drill string at the desired downhole location and harden only after mixing for control of a lost circulation zone. 6 figs.
Downhole material injector for lost circulation control
Glowka, D.A.
1991-01-01
This invention is comprised of an apparatus and method for simultaneously and separately emplacing two streams of different materials through a drillstring in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drillstring at the desired downhole location and harden only after mixing for control of a lost circulation zone.
Wang, Hainan; Thiele, Alexander; Pilon, Laurent
2013-11-15
This paper presents a generalized modified Poisson–Nernst–Planck (MPNP) model derived from first principles based on excess chemical potential and Langmuir activity coefficient to simulate electric double-layer dynamics in asymmetric electrolytes. The model accounts simultaneously for (1) asymmetric electrolytes with (2) multiple ion species, (3) finite ion sizes, and (4) Stern and diffuse layers along with Ohmic potential drop in the electrode. It was used to simulate cyclic voltammetry (CV) measurements for binary asymmetric electrolytes. The results demonstrated that the current density increased significantly with decreasing ion diameter and/or increasing valency |z_{i}| of either ion species. By contrast, the ion diffusion coefficients affected the CV curves and capacitance only at large scan rates. Dimensional analysis was also performed, and 11 dimensionless numbers were identified to govern the CV measurements of the electric double layer in binary asymmetric electrolytes between two identical planar electrodes of finite thickness. A self-similar behavior was identified for the electric double-layer integral capacitance estimated from CV measurement simulations. Two regimes were identified by comparing the half cycle period τ_{CV} and the “RC time scale” τ_{RC} corresponding to the characteristic time of ions’ electrodiffusion. For τ_{RC} ← τ_{CV}, quasi-equilibrium conditions prevailed and the capacitance was diffusion-independent while for τ_{RC} → τ_{CV}, the capacitance was diffusion-limited. The effect of the electrode was captured by the dimensionless electrode electrical conductivity representing the ratio of characteristic times associated with charge transport in the electrolyte and that in the electrode. The model developed here will be useful for simulating and designing various practical electrochemical, colloidal, and biological systems for a wide range of applications.
The characteristics of local atmospheric circulation around the Wolsung NPP in Korea
Lee, G.B.; Lee, M.C.; Song, Y.I.
1998-12-31
The transport of air pollutants in coastal regions has been known to be strongly affected by the mesoscale atmospheric circulations such as sea-land breezes. These mesoscale atmospheric circulations depend on synoptic weather conditions. In this study, a three-dimensional sea-land breeze model was developed to evaluate the effects of the sea and land breezes on the atmospheric dispersion of radioactive materials released from nuclear power plants in Korea. In the model, the hydrostatic primitive equations in the terrain-following coordinate system were used. The mesoscale atmospheric circulation simulation were carried out under various synoptic weather conditions for all seasons around the Wolsung nuclear power plant site.
RF power recovery feedback circulator
Sharamentov, Sergey I.
2011-03-29
A device and method for improving the efficiency of RF systems having a Reflective Load. In the preferred embodiment, Reflected Energy from a superconducting resonator of a particle accelerator is reintroduced to the resonator after the phase of the Reflected Energy is aligned with the phase of the Supply Energy from a RF Energy Source. In one embodiment, a Circulator is used to transfer Reflected Energy from the Reflective Load into a Phase Adjuster which aligns the phase of the Reflected Energy with that of the Supply Energy. The phase-aligned energy is then combined with the Supply Energy, and reintroduced into the Reflective Load. In systems having a constant phase shift, the Phase Adjuster may be designed to shift the phase of the Reflected Energy by a constant amount using a Phase Shifter. In systems having a variety (variable) phase shifts, a Phase Shifter controlled by a phase feedback loop comprising a Phase Detector and a Feedback Controller to account for the various phase shifts is preferable.
Wave Energy Converter (WEC) Array Effects on Wave Current and Sediment Circulation: Monterey Bay CA.
Roberts, Jesse D.; Jones, Craig; Magalen, Jason
2014-09-01
The goal s of this study were to develop tools to quantitatively characterize environments where wave energy converter ( WEC ) devices may be installed and to assess e ffects on hydrodynamics and lo cal sediment transport. A large hypothetical WEC array was investigated using wave, hydrodynamic, and sediment transport models and site - specific average and storm conditions as input. The results indicated that there were significant changes in sediment s izes adjacent to and in the lee of the WEC array due to reduced wave energy. The circulation in the lee of the array was also altered; more intense onshore currents were generated in the lee of the WECs . In general, the storm case and the average case show ed the same qualitative patterns suggesting that these trends would be maintained throughout the year. The framework developed here can be used to design more efficient arrays while minimizing impacts on nearshore environmen ts.
CIRCULATING MOVING BED COMBUSTION PROOF OF CONCEPT
Jukkola, Glen
2010-06-30
Circulating Moving Bed (CMB) combustion technology has its roots in traditional circulating fluidized bed technology and involves a novel method of solid fuel combustion and heat transfer. CMB technology represents a step change in improved performance and cost relative to conventional PC and FBC boilers. The CMB heat exchanger preheats the energy cycle working fluid, steam or air, to the high temperature levels required in systems for advanced power generation. Unique features of the CMB are the reduction of the heat transfer surfaces by about 60% as a result of the enhanced heat transfer rates, flexibility of operation, and about 30% lower cost over existing technology. The CMB Phase I project ran from July 2001 through March 2003. Its objective was to continue development of the CMB technology with a series of proof of concept tests. The tests were conducted at a scale that provided design data for scale up to a demonstration plant. These objectives were met by conducting a series of experiments in ALSTOM Power’s Multi-use Test Facility (MTF). The MTF was modified to operate under CMB conditions of commercial interest. The objective of the tests were to evaluate gas-to-solids heat transfer in the upper furnace, assess agglomeration in the high temperature CMB bubbling bed, and evaluate solids-to-tube heat transfer in the moving bed heat exchanger. The Phase I program results showed that there are still some significant technical uncertainties that needed to be resolved before the technology can be confidently scaled up for a successful demonstration plant design. Work remained in three primary areas: • scale up of gas to solid heat transfer • high temperature finned surface design • the overall requirements of mechanical and process design. The CMB Phase II workscope built upon the results of Phase I and specifically addressed the remaining technical uncertainties. It included a scaled MTF heat transfer test to provide the necessary data to scale up gas
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Li General Table The General Table for 7Li is subdivided into the following categories: Reviews Ground State Properties Shell Model Cluster Model Other Theoretical Work Model Calculations Photodisintegration Polarization Fission and Fusion Elastic and Inelastic Scattering Projectile Fragmentation and Multifragmentation Astrophysical Hyperfine Structure b-decay Muons Hypernuclei and Mesons Hypernuclei and Baryons Pion, Kaon and Eta-Mesons Other Work Applications
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B General Tables The General Table for 8B is subdivided into the following categories: Reviews Ground State Properties Shell Model Cluster Model Other Models Photodisintegration and Coulomb Dissociation Elastic and Inelastic Scattering Fragmentation Reactions Astrophysical b Decay Nucleon Spatial Distribution
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Li General Tables The General Table for 8Li is subdivided into the following categories: Reviews Ground State Properties Shell Model Cluster Model Other Models Photodissociation Fusion and Fission Elastic and Inelastic Scattering Fragmentation Reactions Astrophysical b Decay Hypernuclei Pions, Kaons and h-mesons
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Li General Table The General Table for 9Li is subdivided into the following categories: Shell Model Cluster Model Theoretical Ground State Properties Special States Other Model Calculations Complex Reactions Beta-Decay Pions Muons Photodisintegration Elastic and Inelastic Scattering Electromagnetic Transitions Astrophysical
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Li General Table The General Table for 10Li is subdivided into the following categories: Reviews Theoretical Ground State Properties Shell Model Cluster Model Other Models Special States Astrophysical Electromagnetic Transitions Hypernuclei Photodisintegration Light-Ion and Neutron Induced Reactions These General Tables correspond to the 2003 preliminary evaluation of ``Energy Levels of Light Nuclei, A = 10''. The prepublication version of A = 10 is available on this website in PDF format: A =
Defining the Effectiveness of UV Lamps Installed in Circulating...
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Defining the Effectiveness of UV Lamps Installed in Circulating...
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Reversing the Circulation of Magnetic Vortices
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the Circulation of Magnetic Vortices Print Wednesday, 31 July 2013 00:00 In magnetic media, information is stored in binary form-one or zero, depending on which way the...
Reversing the Circulation of Magnetic Vortices
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Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in...
Reversing the Circulation of Magnetic Vortices
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Reversing the Circulation of Magnetic Vortices Reversing the Circulation of Magnetic Vortices Print Wednesday, 31 July 2013 00:00 In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny
Effects of a geomagnetic storm on thermospheric circulation. Master's thesis
Brinkman, D.G.
1987-01-01
The motions of the thermosphere and its interactions with the ionosphere during a geomagnetic storm are of current interest to space scientists. A two-dimensional model was used to simulate the thermospheric response to the impulsive high-latitude heating associated with a geomagnetic storm. The storm-induced motions can be characterized by an initial period of transient waves followed by the development of a mean circulation. These motions generate an electrical-current system that is on the same order of magnitude as, and in the opposite sense to the normal s/sub q/ current system. Model-simulated winds and electrical currents were then compared to observations.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Johnson, Raymond H.; Truax, Ryan A.; Lankford, David A.; Stone, James J.
2016-02-03
Solid-phase iron concentrations and generalized composite surface complexation models were used to evaluate procedures in determining uranium sorption on oxidized aquifer material at a proposed U in situ recovery (ISR) site. At the proposed Dewey Burdock ISR site in South Dakota, USA, oxidized aquifer material occurs downgradient of the U ore zones. Solid-phase Fe concentrations did not explain our batch sorption test results,though total extracted Fe appeared to be positively correlated with overall measured U sorption. Batch sorption test results were used to develop generalized composite surface complexation models that incorporated the full genericsorption potential of each sample, without detailedmore » mineralogiccharacterization. The resultant models provide U sorption parameters (site densities and equilibrium constants) for reactive transport modeling. The generalized composite surface complexation sorption models were calibrated to batch sorption data from three oxidized core samples using inverse modeling, and gave larger sorption parameters than just U sorption on the measured solidphase Fe. These larger sorption parameters can significantly influence reactive transport modeling, potentially increasing U attenuation. Because of the limited number of calibration points, inverse modeling required the reduction of estimated parameters by fixing two parameters. The best-fit models used fixed values for equilibrium constants, with the sorption site densities being estimated by the inversion process. While these inverse routines did provide best-fit sorption parameters, local minima and correlated parameters might require further evaluation. Despite our limited number of proxy samples, the procedures presented provide a valuable methodology to consider for sites where metal sorption parameters are required. Furthermore, these sorption parameters can be used in reactive transport modeling to assess downgradient metal attenuation, especially when no other
Impact of cloud radiative heating on East Asian summer monsoon circulation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Guo, Zhun; Zhou, Tianjun; Wang, Minghuai; Qian, Yun
2015-07-17
The impacts of cloud radiative heating on East Asian Summer Monsoon (EASM) over the southeastern China (105°-125°E, 20°-35°N) are explained by using the Community Atmosphere Model version 5 (CAM5). Sensitivity experiments demonstrate that the radiative heating of clouds leads to a positive effect on the local EASM circulation over southeastern China. Without the radiative heating of cloud, the EASM circulation and precipitation would be much weaker than that in the normal condition. The longwave heating of clouds dominates the changes of EASM circulation. The positive effect of clouds on EASM circulation is explained by the thermodynamic energy equation, i.e. themore » different heating rate between cloud base and cloud top enhances the convective instability over southeastern China, which enhances updraft consequently. The strong updraft would further result in a southward meridional wind above the center of the updraft through Sverdrup vorticity balance.« less
Impact of cloud radiative heating on East Asian summer monsoon circulation
Guo, Zhun; Zhou, Tianjun; Wang, Minghuai; Qian, Yun
2015-07-17
The impacts of cloud radiative heating on East Asian Summer Monsoon (EASM) over the southeastern China (105°-125°E, 20°-35°N) are explained by using the Community Atmosphere Model version 5 (CAM5). Sensitivity experiments demonstrate that the radiative heating of clouds leads to a positive effect on the local EASM circulation over southeastern China. Without the radiative heating of cloud, the EASM circulation and precipitation would be much weaker than that in the normal condition. The longwave heating of clouds dominates the changes of EASM circulation. The positive effect of clouds on EASM circulation is explained by the thermodynamic energy equation, i.e. the different heating rate between cloud base and cloud top enhances the convective instability over southeastern China, which enhances updraft consequently. The strong updraft would further result in a southward meridional wind above the center of the updraft through Sverdrup vorticity balance.
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Reversing the Circulation of Magnetic Vortices
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can
Van Gorder, Robert A.
2014-11-15
In R. A. Van Gorder, General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation, Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, Comment on General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation [Phys. Fluids 26, 065105 (2014)], Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it was clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.
Natural Circulation Patterns in the VHTR Air-Ingress Accident and Related Issues
Chang H. Oh; Eung S. Kim
2012-08-01
Natural circulation patterns in the VHTR during a hypothetical air-ingress accident have been investigated using computational fluid dynamic (CFD) methods in order to compare results from the previous 1-D model which was developed using GAMMA code for the air-ingress analyses. The GT-MHR 600 MWt reactor was selected to be the reference design and modeled by a half symmetric 3-D geometry using FLUENT 6.3, a commercial CFD code. CFD simulations were carried out as the steady-state calculation, and the boundary conditions were either assumed or provided from the 1-D GAMMA code results. Totally, 12 different cases have been reviewed, and many notable results have been obtained through in this work. According to the simulations, natural circulation patterns in the reactor were quite different from the previous 1-D assumptions. A large re-circulation flow with thermal stratification phenomena was clearly observed in the hot-leg and the lower plenum in the 3-D model. This re-circulation flow provided about an order faster air-ingress speed (0.46 m/s in superficial velocity) than previously predicted by 1-D modeling (0.02~0.03 m/s). It indicates that the 1-D air-ingress modeling may significantly distort the air-ingress scenario and consequences. In addition, complicated natural circulation patterns are eventually expected to result in very complex graphite oxidations and corrosion behaviors.
U.S. Energy Information Administration (EIA) Indexed Site
General Engineers The U.S. Energy Information Administration (EIA) within the Department of Energy has forged a world-class information program that stresses quality, teamwork, and employee growth. In support of our program, we offer a variety of profes- sional positions, including the General Engineer, whose work is associated with analytical studies and evaluation projects pertaining to the operations of the energy industry. Responsibilities: General Engineers perform or participate in one or
Hietala, Niklas Hnninen, Risto
2014-11-15
Van Gorder considers a formulation of the local induction approximation, which allows the vortex to move in the direction of the reference axis [General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation, Phys. Fluids 26, 065105 (2014)]. However, in his analytical and numerical study he does not use it. A mistake in the torsion of a helical vortex is also corrected.
Broader source: Energy.gov [DOE]
This position is located in Office of Standard Contract Management, within the Office of the General Counsel (GC). The purpose of the position is to conduct technical and engineering reviews of the...
Lifshutz, N.; Pierce, M.
1997-08-01
The CertiTest 8160 is a Condensation Nucleus Counter (CNC) based filtration test stand which permits measurement of penetration as a function of particle size. The Model 8140 is also a CNC based filtration test stand which provides a single penetration measurement for a fixed particle distribution aerosol challenge. A study was carried out measuring DOP penetration on a broad range of flat filtration media at various face velocities to compare these two instruments. The tests done on the CertiTest 8160 incorporated a range of particle sizes which encompassed the most penetrating particle size (MPPS). In this paper we present a correlation between the MPPS penetration as measured by the CertiTest 8160 and the penetration values obtained on the Model 8140. We observed that at the lowest air face velocities of the study the Model 8140 tended to overpredict the MPPS penetration as measured by the CertiTest 8160. We also present a correlation of MPPS penetration with face velocity which may be of use for extrapolation purposes. 5 refs., 8 figs.
Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C; Brooks, Scott C; Pace, Molly; Kim, Young Jin; Jardine, Philip M; Watson, David B
2007-01-01
This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing NE equilibrium reactions and a set of reactive transport equations of M-NE kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.
Reducing mode circulating fluid bed combustion
Lin, Yung-Yi; Sadhukhan, Pasupati; Fraley, Lowell D.; Hsiao, Keh-Hsien
1986-01-01
A method for combustion of sulfur-containing fuel in a circulating fluid bed combustion system wherein the fuel is burned in a primary combustion zone under reducing conditions and sulfur captured as alkaline sulfide. The reducing gas formed is oxidized to combustion gas which is then separated from solids containing alkaline sulfide. The separated solids are then oxidized and recycled to the primary combustion zone.
Ganguly, A. E-mail: aganguly@maths.iitkgp.ernet.in; Das, A.
2014-11-15
We consider one-dimensional stationary position-dependent effective mass quantum model and derive a generalized Korteweg-de Vries (KdV) equation in (1+1) dimension through Lax pair formulation, one being the effective mass Schrödinger operator and the other being the time-evolution of wave functions. We obtain an infinite number of conserved quantities for the generated nonlinear equation and explicitly show that the new generalized KdV equation is an integrable system. Inverse scattering transform method is applied to obtain general solution of the nonlinear equation, and then N-soliton solution is derived for reflectionless potentials. Finally, a special choice has been made for the variable mass function to get mass-deformed soliton solution. The influence of position and time-dependence of mass and also of the different representations of kinetic energy operator on the nature of such solitons is investigated in detail. The remarkable features of such solitons are demonstrated in several interesting figures and are contrasted with the conventional KdV-soliton associated with constant-mass quantum model.
ATMOSPHERIC CIRCULATION OF BROWN DWARFS: JETS, VORTICES, AND TIME VARIABILITY
Zhang, Xi; Showman, Adam P.
2014-06-10
A variety of observational evidence demonstrates that brown dwarfs exhibit active atmospheric circulations. In this study we use a shallow-water model to investigate the global atmospheric dynamics in the stratified layer overlying the convective zone on these rapidly rotating objects. We show that the existence and properties of the atmospheric circulation crucially depend on key parameters including the energy injection rate and radiative timescale. Under conditions of strong internal heat flux and weak radiative dissipation, a banded flow pattern comprised of east-west jet streams spontaneously emerges from the interaction of atmospheric turbulence with the planetary rotation. In contrast, when the internal heat flux is weak and/or radiative dissipation is strong, turbulence injected into the atmosphere damps before it can self-organize into jets, leading to a flow dominated by transient eddies and isotropic turbulence instead. The simulation results are not very sensitive to the form of the forcing. Based on the location of the transition between jet-dominated and eddy-dominated regimes, we suggest that many brown dwarfs may exhibit atmospheric circulations dominated by eddies and turbulence (rather than jets) due to the strong radiative damping on these worlds, but a jet structure is also possible under some realistic conditions. Our simulated light curves capture important features from observed infrared light curves of brown dwarfs, including amplitude variations of a few percent and shapes that fluctuate between single-peak and multi-peak structures. More broadly, our work shows that the shallow-water system provides a useful tool to illuminate fundamental aspects of the dynamics on these worlds.
Van Gorder, Robert A.
2014-06-15
In his study of superfluid turbulence in the low-temperature limit, Svistunov [Superfluid turbulence in the low-temperature limit, Phys. Rev. B 52, 3647 (1995)] derived a Hamiltonian equation for the self-induced motion of a vortex filament. Under the local induction approximation (LIA), the Svistunov formulation is equivalent to a nonlinear dispersive partial differential equation. In this paper, we consider a family of rotating vortex filament solutions for the LIA reduction of the Svistunov formulation, which we refer to as the 2D LIA (since it permits a potential formulation in terms of two of the three Cartesian coordinates). This class of solutions holds the well-known Hasimoto-type planar vortex filament [H. Hasimoto, Motion of a vortex filament and its relation to elastica, J. Phys. Soc. Jpn. 31, 293 (1971)] as one reduction and helical solutions as another. More generally, we obtain solutions which are periodic in the space variable. A systematic analytical study of the behavior of such solutions is carried out. In the case where vortex filaments have small deviations from the axis of rotation, closed analytical forms of the filament solutions are given. A variety of numerical simulations are provided to demonstrate the wide range of rotating filament behaviors possible. Doing so, we are able to determine a number of vortex filament structures not previously studied. We find that the solution structure progresses from planar to helical, and then to more intricate and complex filament structures, possibly indicating the onset of superfluid turbulence.
Colbert, J.J.; Sheehan, K.A.
1995-08-16
This document describes the structure, organization, and mathematical formulations for the Stand-Damage Model and the Biological basis for these formulations. Growth, mortality, and regeneration are modeled along with the effects of user-prescribed defoliation and stand-management actions. The appendices provide a full description of the logic and mathematics in the form of code listings, structure charts, and files.
The stability of the thermohaline circulation in global warming experiments
Schmittner, A.; Stocker, T.F.
1999-04-01
A simplified climate model of the coupled ocean-atmosphere system is used to perform extensive sensitivity studies concerning possible future climate change induced by anthropogenic greenhouse gas emissions. Supplemented with an active atmospheric hydrological cycle, experiments with different rates of CO{sub 2} increase and different climate sensitivities are performed. The model exhibits a threshold value of atmospheric CO{sub 2} concentration beyond which the North Atlantic Deep Water formation stops and never recovers. For a climate sensitivity that leads to an equilibrium warming of 3.6 C for a doubling of CO{sub 2} and a rate of CO{sub 2} increase of 1% yr{sup {minus}1}, the threshold lies between 650 and 700 ppmv. Moreover, it is shown that the stability of the thermohaline circulation depends on the rate of increase of greenhouse gases. For a slower increase of atmospheric pCO{sub 2} the final amount that can be reached without a shutdown of the circulation is considerably higher. This rate-sensitive response is due to the uptake of heat and excess freshwater from the uppermost layers to the deep ocean. The increased equator-to-pole freshwater transport in a warmer atmosphere is mainly responsible for the cessation of deep water formation in the North Atlantic. Another consequence of the enhanced latent heat transport is a stronger warming at high latitudes. A model version with fixed water vapor transport exhibits uniform warming at all latitudes. The inclusion of a simple parameterization of the ice-albedo feedback increases the model sensitivity and further decreases the pole-to-equator temperature difference in a greenhouse climate. The possible range of CO{sub 2} threshold concentrations and its dependency on the rate of CO{sub 2} increase, on the climate sensitivity, and on other model parameters are discussed.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
General Publications General Publications Print ALS Strategic Plan 2015-19 cover image An updated version of the ALS Strategic Plan, covering the five-year period from 2015 to 2019. As in the 2014-18 version, Section I gives a brief synopsis on beamline and endstation projects. The science drivers behind these projects are explained in greater detail in Section II, and a very brief description of emerging plans for a ALS-U are in Section III. Soft X-ray Science Opportunities Using
Nishi, Sakine; Kobayashi, Tsutomu
2015-03-31
The galilean genesis scenario is an alternative to inflation in which the universe starts expanding from Minkowski in the asymptotic past by violating the null energy condition stably. Several concrete models of galilean genesis have been constructed so far within the context of galileon-type scalar-field theories. We give a generic, unified description of the galilean genesis scenario in terms of the Horndeski theory, i.e., the most general scalar-tensor theory with second-order field equations. In doing so we generalize the previous models to have a new parameter (denoted by α) which results in controlling the evolution of the Hubble rate. The background dynamics is investigated to show that the generalized galilean genesis solution is an attractor, similarly to the original model. We also study the nature of primordial perturbations in the generalized galilean genesis scenario. In all the models described by our generalized genesis Lagrangian, amplification of tensor perturbations does not occur as opposed to what happens in quasi-de Sitter inflation. We show that the spectral index of curvature perturbations is determined solely from the parameter α and does not depend on the other details of the model. In contrast to the original model, a nearly scale-invariant spectrum of curvature perturbations is obtained for a specific choice of α.
TRANSPORT BY MERIDIONAL CIRCULATIONS IN SOLAR-TYPE STARS
Wood, T. S.; Brummell, N. H.
2012-08-20
Transport by meridional flows has significant consequences for stellar evolution, but is difficult to capture in global-scale numerical simulations because of the wide range of timescales involved. Stellar evolution models therefore usually adopt parameterizations for such transport based on idealized laminar or mean-field models. Unfortunately, recent attempts to model this transport in global simulations have produced results that are not consistent with any of these idealized models. In an effort to explain the discrepancies between global simulations and idealized models, here we use three-dimensional local Cartesian simulations of compressible convection to study the efficiency of transport by meridional flows below a convection zone in several parameter regimes of relevance to the Sun and solar-type stars. In these local simulations we are able to establish the correct ordering of dynamical timescales, although the separation of the timescales remains unrealistic. We find that, even though the generation of internal waves by convective overshoot produces a high degree of time dependence in the meridional flow field, the mean flow has the qualitative behavior predicted by laminar, 'balanced' models. In particular, we observe a progressive deepening, or 'burrowing', of the mean circulation if the local Eddington-Sweet timescale is shorter than the viscous diffusion timescale. Such burrowing is a robust prediction of laminar models in this parameter regime, but has never been observed in any previous numerical simulation. We argue that previous simulations therefore underestimate the transport by meridional flows.
Gangwer, T
1980-01-01
A mechanism for coal liquefaction, based on the concept of thermal cleavage-hydrogen capping donor complexes, is proposed and the quantitative agreement between the derived rate laws and the kinetic data obtained from fifteen publications is presented. The mechanism provides rate laws which describe the preasphaltene, asphaltene, oil and gas time/yield curves for the coal liquefaction process. A simplistic dissolution model is presented and used to relate the proposed mechanism to the experimentally observed products. Based on the quality of the mechanistic fit to the reported coal liquefaction systems, which cover a diverse range of reaction conditions, coal types and donor solvent compositions, it is proposed that the donor solvent/thermal bond cleavage/hydrogen capping mechanism provides a good, quantitative description of the rate limiting process. Interpretation of the rate constant/temperature dependencies in terms of transition state theory indicates formation of the activated complex can involve either physically or chemically controlled steps. A uniform free energy of activation of 52 kcal was found for the diverse liquefaction systems indicating a common transition state describes the reactions. Thus the proposed mechanism unifies the diverse liquefaction kinetic data by using a set of uniform reaction sequences, which have a common transition state, to describe the conversion chemistry. The mechanism thereby creates a common base for intercomparison, interpretation and evaluation of coal conversion for the broad range of processes currently being investigated in the liquefaction field.
Nucla circulating atmospheric fluidized bed demonstration project
Not Available
1991-01-31
During the fourth quarter of 1990, steady-state performance testing at the Nucla Circulating Fluidized Bed (CFB) resumed under sponsorship of the US Department of Energy. Co-sponsorship of the Demonstration Test Program by the Electric Power Research Institute (EPRI) was completed on June 15, 1990. From October through December, 1990, Colorado-Ute Electric Association (CUEA) completed a total of 23 steady-state performance tests, 4 dynamic tests, and set operating records during November and December as the result of improved unit operating reliability. Highlight events and achievements during this period of operation are presented.
Fraser, D.W.H.; Abdelmessih, A.H.
1995-09-01
A general unified model is developed to predict one-component critical two-phase pipe flow. Modelling of the two-phase flow is accomplished by describing the evolution of the flow between the location of flashing inception and the exit (critical) plane. The model approximates the nonequilibrium phase change process via thermodynamic equilibrium paths. Included are the relative effects of varying the location of flashing inception, pipe geometry, fluid properties and length to diameter ratio. The model predicts that a range of critical mass fluxes exist and is bound by a maximum and minimum value for a given thermodynamic state. This range is more pronounced at lower subcooled stagnation states and can be attributed to the variation in the location of flashing inception. The model is based on the results of an experimental study of the critical two-phase flow of saturated and subcooled water through long tubes. In that study, the location of flashing inception was accurately controlled and adjusted through the use of a new device. The data obtained revealed that for fixed stagnation conditions, the maximum critical mass flux occurred with flashing inception located near the pipe exit; while minimum critical mass fluxes occurred with the flashing front located further upstream. Available data since 1970 for both short and long tubes over a wide range of conditions are compared with the model predictions. This includes test section L/D ratios from 25 to 300 and covers a temperature and pressure range of 110 to 280{degrees}C and 0.16 to 6.9 MPa. respectively. The predicted maximum and minimum critical mass fluxes show an excellent agreement with the range observed in the experimental data.
Pulling the Meridional Overturning Circulation From the South DESC0005100
Cessi, Paola; Wolfe, Christopher L.
2015-11-25
This project concerned the Atlantic Meridional Overturning Circulation (AMOC), its stability, variability and sensitivity to atmospheric forcing, both mechanical (wind-stress) and thermodynamical (heat and freshwater surface fluxes). The focus of the study is the interhemispheric cell in the largely adiabatic regime, where the flow is characterized by a descending branch in the high latitudes of the North Atlantic and the upwelling branch in the Antarctic Circumpolar Current (ACC) region of the Southern Ocean. These two end points are connected by shared isopycnals along which the flow takes place. The approach is to systematically study the amplitude and frequency of the AMOC’s response to localized buoyancy with an ocean-only model in both coarse and high-resolution configurations, analyzed with innovative diagnostics, focused on the “residual overturning circulation” (ROC), which is the proper measure of the transport of heat and other tracers.
Hydrodynamic aspects of a circulating fluidized bed with internals
Balasubramanian, N.; Srinivasakannan, C.
1998-06-01
An attempt is made to examine the influence of internals (baffles) in the riser of the circulating fluidized bed. Experiments are conducted in a circulating fluidized bed, having perforated plates with different free areas. It is noticed from the present work that a circulating fluidized bed having 45% free area gives uniform solids concentration and pressure drop along the length of the riser. In addition to the uniformity, the circulating fluidized bed with internals gives higher pressure drop (solids concentration) compared to a conventional circulating fluidized bed. For internals having 67.6% free area the pressure drop is higher at the lower portion of the riser compared to the upper portion, similar to a conventional circulating fluidized bed. For 30% free area plates the solids concentration varies axially within the stage and remains uniform from stage to stage.
RETRAN-02 comparison of natural circulation flow rates at Babcock and Wilcox 177-FA plants
Simms, N.T.
1985-07-01
A very important aspect of nuclear steam supply system (NSSS) model development is the process of comparing the computer model results against actual plant responses. Good comparisons will qualify the computer model for specific engineering analyses. Flow rates and decay heat power levels were obtained from planned and unplanned natural circulation events that occurred at Arkansas Nuclear One, Crystal River, Davis-Besse, and Oconee nuclear power plants. A oneloop RETRAN model of the Oconee NSSS is used to attain a spectrum of steady-state equilibrium conditions at different power levels of 25, 50, 75, and 100 MW. The benchmark comparisons are respectable. The comparisons also illustrate the ability of the Babcock and Wilcox raised-loop plant to induce a greater natural circulation flow rate.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Daleu, C. L.; Plant, R. S.; Woolnough, S. J.; Sessions, S.; Herman, M. J.; Sobel, A.; Wang, S.; Kim, D.; Cheng, A.; Bellon, G.; et al
2016-03-18
As part of an international intercomparison project, the weak temperature gradient (WTG) and damped gravity wave (DGW) methods are used to parameterize large-scale dynamics in a set of cloud-resolving models (CRMs) and single column models (SCMs). The WTG or DGW method is implemented using a configuration that couples a model to a reference state defined with profiles obtained from the same model in radiative-convective equilibrium. We investigated the sensitivity of each model to changes in SST, given a fixed reference state. We performed a systematic comparison of the WTG and DGW methods in different models, and a systematic comparison ofmore » the behavior of those models using the WTG method and the DGW method. The sensitivity to the SST depends on both the large-scale parameterization method and the choice of the cloud model. In general, SCMs display a wider range of behaviors than CRMs. All CRMs using either the WTG or DGW method show an increase of precipitation with SST, while SCMs show sensitivities which are not always monotonic. CRMs using either the WTG or DGW method show a similar relationship between mean precipitation rate and column-relative humidity, while SCMs exhibit a much wider range of behaviors. DGW simulations produce large-scale velocity profiles which are smoother and less top-heavy compared to those produced by the WTG simulations. Lastly, these large-scale parameterization methods provide a useful tool to identify the impact of parameterization differences on model behavior in the presence of two-way feedback between convection and the large-scale circulation.« less
Process simulation of a circulating fluidized bed coal combustor
Legros, R.; Sotudeh-Gharebaagh, R.; Paris, J.; Chaouki, J.; Preto, F.
1995-12-31
The focus of this work is the development of a process simulator for a Circulating Fluidized Bed coal Combustor (CFBC). The development of a simple comprehensive model for coal combustion in a CFBC is based on existing work reported in the literature. The model combines the hydrodynamic features of a CFBC riser with the different reaction steps involved during coal combustion, including the sulphur capture by limestone particles. The commercial process simulation program ASPEN PLUS was chosen as a framework for the development of the CFBC process simulator. ASPEN PLUS has been widely accepted in the chemical industry as a design tool because of its ability to simulate various chemical processes, including power generation cycles. In ASPEN PLUS, several ideal chemical reactor models involving solids are available for simulation purposes. The CFBC process simulator is constructed using several ASPEN PLUS unit operation blocks. The information required for each block is obtained from the combustion and hydrodynamic models, which are inserted into the simulation flowsheet as subroutines or internal programs. The resulting CFBC process simulator is used to predict the performance of the CFBC pilot plant at Energy Research laboratories, CANMET in Ottawa.
Dynamics and efficiency of magnetic vortex circulation reversal...
Office of Scientific and Technical Information (OSTI)
Dynamics and efficiency of magnetic vortex circulation reversal Not Available Temp HTML Storage 2: Urbnek, Michal; Uhl, Vojtch; Lambert, Charles-Henri; Kan, Jimmy J.; ...
Circulating heat exchangers for oscillating wave engines and...
Office of Scientific and Technical Information (OSTI)
heat exchangers for oscillating wave engines and refrigerators Title: Circulating heat exchangers for oscillating wave engines and refrigerators An oscillating-wave engine or ...
Progress in The Lost Circulation Technology Development Program
Glowka, D.A.; Schafer, D.M.; Loeppke, G.E.; Wright, E.K.
1991-01-01
Lost circulation is the loss of drilling fluid from the wellbore to fractures or pores in the rock formation. In geothermal drilling, lost circulation is often a serious problem that contributes greatly to the cost of the average geothermal well. The Lost Circulation Technology Development Program is sponsored at Sandia National Laboratories by the US Department of Energy. The goal of the program is to reduce lost circulation costs by 30--50{percent} through the development of mitigation and characterization technology. This paper describes the technical progress made in this program during the period April, 1990--March, 1991. 4 refs., 15 figs., 1 tab.
Nucla circulating atmospheric fluidized bed demonstration project
Keith, Raymond E.
1991-10-01
Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute's decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.
Energy Science and Technology Software Center (OSTI)
2004-10-18
The Community Atmosphere Model (CAM) is an atmospheric general circulation model that solves equations for atmospheric dynamics and physics. CAM is an outgrowth of the Community Climate Model at the National Center for Atmospheric Research (NCAR) and was developed as a joint collaborative effort between NCAR and several DOE laboratories, including LLNL. CAM contains several alternative approaches for advancing the atmospheric dynamics. One of these approaches uses a finite-volume method originally developed by personnel atmore » NASNGSFC, We have developed a scalable version of the finite-volume solver for massively parallel computing systems. FV-CAM is meant to be used in conjunction with the Community Atmosphere Model. It is not stand-alone.« less
Basement Structure and Implications for Hydrothermal Circulation...
California Abstract Detailed surface mapping, subsurface drill hole data, and geophysical modeling are the basis of a structural and hydrothermal model for the western part of Long...
Solar powered circulation pump development. Final report
Johnson, A.L.
1980-09-01
An iterative design and evaluation process was undertaken to develop a prototype solar powered liquid circulation pump. The first effort was to review the state-of-the-art of liquid piston heat engines. Next a morphological analysis of the original concept was performed. An analysis of the pump performance from a theoretical basis was performed by deriving and solving the equations governing the cycle. The results are documented. An experimental evaluation of the condensing phenomena was performed. The design of the boiler was then undertaken. This effort showed a fundamental physical limitation imposed by the original geometry and the physics of water boiling. In an effort to resolve this problem, a number of alternate configurations were examined, with the result being that the boiler and heat pipe elements of the design were entirely eliminated. In their stead it was assumed that the boiling could be conducted in the solar panel. A number of solar panel designs were examined, and the most appropriate type of solar panel is described in the appendix. A 1/4th scale unit was fabricated and tested. The overall efficiency was approximately 1% at the design point, compared with a theoretical limit of 1.6% for the given operating conditions. The production costs of the full size pump were examined. Finally systems integration aspects were considered and the results presented.
Do Coupled Climate Models Correctly SImulate the Upward Branch of the Deept Ocean Global Conveyor?
Sarmiento, Jorge L; Downes, Stephanie; Bianchi, Daniele
2013-01-17
The large-scale meridional overturning circulation (MOC) connects the deep ocean, a major reservoir of carbon, to the other components of the climate system and must therefore be accurately represented in Earth System Models. Our project aims to address the specific question of the pathways and mechanisms controlling the upwelling branch of the MOC, a subject of significant disagreement between models and observational syntheses, and among general circulation models. Observations of these pathways are limited, particularly in regions of complex hydrography such as the Southern Ocean. As such, we rely on models to examine theories of the overturning circulation, both physically and biogeochemically. This grant focused on a particular aspect of the meridional overturning circulation (MOC) where there is currently significant disagreement between models and observationally based analyses of the MOC, and amongst general circulation models. In particular, the research focused on addressing the following questions: 1. Where does the deep water that sinks in the polar regions rise to the surface? 2. What processes are responsible for this rise? 3. Do state-of-the-art coupled GCMs capture these processes? Our research had three key components: observational synthesis, model development and model analysis. In this final report we outline the key results from these areas of research for the 2007 to 2012 grant period. The research described here was carried out primarily by graduate student, Daniele Bianchi (now a Postdoc at McGill University, Canada), and Postdoc Stephanie Downes (now a Research Fellow at The Australian national University, Australia). Additional support was provided for programmers Jennifer Simeon as well as Rick Slater.
Cloudy Sky RRTM Shortwave Radiative Transfer and Comparison to the Revised ECMWF Shortwave Model
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Cloudy Sky RRTM Shortwave Radiative Transfer and Comparison to the Revised ECMWF Shortwave Model M. J. Iacono, J. S. Delamere, E. J. Mlawer, and S. A. Clough Atmospheric and Environmental Research, Inc. Lexington, Massachusetts J.-J. Morcrette European Centre for Medium-Range Weather Forecasts Reading, United Kingdom Introduction An important step toward improving radiative transfer codes in general circulation models (GCMs) is their thorough evaluation by comparison to measurements directly, or
Constrained Generalized Supersymmetries
Toppan, Francesco; Kuznetsova, Zhanna
2005-10-17
We present a classification of admissible types of constraint (hermitian, holomorphic, with reality condition on the bosonic sectors, etc.) for generalized supersymmetries in the presence of complex spinors. A generalized supersymmetry algebra involving n-component real spinors Qa is given by the anticommutators {l_brace}Q{sub a},Q{sub b}{r_brace} = Z{sub ab} where the matrix Z appearing in the r.h.s. is the most general symmetric matrix. A complex generalized supersymmetry algebra is expressed in terms of complex spinors Qa and their complex conjugate Q* a. The most general (with a saturated r.h.s.) algebra is in this case given by {l_brace}Q{sub a},Q{sub b}{r_brace} P{sub ab}{l_brace}Q*{sub a}, Q*{sub b}{r_brace} = P*{sub ab}{l_brace}Q{sub a},Q*{sub b}{r_brace} = R{sub ab} where the matrix Pab is symmetric, while Rab is hermitian. The bosonic right hand side can be expressed in terms of the rank-k totally antisymmetric tensors P{sub ab} {sigma}k(C{gamma}{sub [{mu}}{sub 1...{mu}}{sub k]}){sub ab}P{sup [{mu}{sup 1...{mu}{sup k}]}.The decomposition in terms of anti-symmetric tensors for any space-time up to dimension D = 13 is presented. Real type, complex type, and quaternionic type space-times are classified. Any restriction on the saturated bosonic generators that allows all possible combinations of these tensors is in principle admissible by a Lorenz-covariant requirement. We investigate division algebra constraints and their influence on physical models. High spin theory models are presented as examples of the applications of such models.
The Role of Eddy-Tansport in the Thermohaline Circulation
Dr. Paola Cessi
2011-11-17
Several research themes were developed during the course of this project. (1) Low-frequency oceanic varibility; (2) The role of eddies in the Antarctic Circumpolar Current (ACC) region; (3) Deep stratification and the overturning circulation. The key findings were as follows: (1) The stratification below the main thermocline (at about 500m) is determined in the circumpolar region and then communicated to the enclosed portions of the oceans through the overturning circulation. (2) An Atlantic pole-to-pole overturning circulation can be maintained with very small interior mixing as long as surface buoyancy values are shared between the northern North Atlantic and the ACC region.
Circulating heat exchangers for oscillating wave engines and refrigerators
Swift, Gregory W.; Backhaus, Scott N.
2003-10-28
An oscillating-wave engine or refrigerator having a regenerator or a stack in which oscillating flow of a working gas occurs in a direction defined by an axis of a trunk of the engine or refrigerator, incorporates an improved heat exchanger. First and second connections branch from the trunk at locations along the axis in selected proximity to one end of the regenerator or stack, where the trunk extends in two directions from the locations of the connections. A circulating heat exchanger loop is connected to the first and second connections. At least one fluidic diode within the circulating heat exchanger loop produces a superimposed steady flow component and oscillating flow component of the working gas within the circulating heat exchanger loop. A local process fluid is in thermal contact with an outside portion of the circulating heat exchanger loop.
Dynamic Switching of the Spin Circulation in Tapered Magnetic...
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which allows to record an image of the in-plane circulation of the magnetic vortex. The topology of vortices-areas where there is a spinning motion around an imaginary axis-is a...
Property:Building/SPElectrtyUsePercCirculationFans | Open Energy...
sePercCirculationFans" Showing 25 pages using this property. (previous 25) (next 25) S Sweden Building 05K0001 + 18.6715328229 + Sweden Building 05K0002 + 0.0 + Sweden Building...
Potential Aerosol Indirect Effects on Atmospheric Circulation...
Office of Scientific and Technical Information (OSTI)
the complex processes involved are poorly understood and represented in climate models. Here we report that aerosol indirect effect on deep convective cloud systems can lead ...
The atmospheric circulation of the super Earth GJ 1214b: Dependence on composition and metallicity
Kataria, T.; Showman, A. P.; Fortney, J. J.; Marley, M. S.; Freedman, R. S.
2014-04-20
We present three-dimensional atmospheric circulation models of GJ 1214b, a 2.7 Earth-radius, 6.5 Earth-mass super Earth detected by the MEarth survey. Here we explore the planet's circulation as a function of atmospheric metallicity and atmospheric composition, modeling atmospheres with a low mean molecular weight (MMW; i.e., H{sub 2}-dominated) and a high MMW (i.e., water- and CO{sub 2}-dominated). We find that atmospheres with a low MMW have strong day-night temperature variations at pressures above the infrared photosphere that lead to equatorial superrotation. For these atmospheres, the enhancement of atmospheric opacities with increasing metallicity lead to shallower atmospheric heating, larger day-night temperature variations, and hence stronger superrotation. In comparison, atmospheres with a high MMW have larger day-night and equator-to-pole temperature variations than low MMW atmospheres, but differences in opacity structure and energy budget lead to differences in jet structure. The circulation of a water-dominated atmosphere is dominated by equatorial superrotation, while the circulation of a CO{sub 2}-dominated atmosphere is instead dominated by high-latitude jets. By comparing emergent flux spectra and light curves for 50× solar and water-dominated compositions, we show that observations in emission can break the degeneracy in determining the atmospheric composition of GJ 1214b. The variation in opacity with wavelength for the water-dominated atmosphere leads to large phase variations within water bands and small phase variations outside of water bands. The 50× solar atmosphere, however, yields small variations within water bands and large phase variations at other characteristic wavelengths. These observations would be much less sensitive to clouds, condensates, and hazes than transit observations.
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C General Tables The General Table for 8C is subdivided into the following categories: Reviews Other Theoretical Work...
Simulation of NOx emission in circulating fluidized beds burning low-grade fuels
Afsin Gungor
2009-05-15
Nitrogen oxides are a major environmental pollutant resulting from combustion. This paper presents a modeling study of pollutant NOx emission resulting from low-grade fuel combustion in a circulating fluidized bed. The simulation model accounts for the axial and radial distribution of NOx emission in a circulating fluidized bed (CFB). The model results are compared with and validated against experimental data both for small-size and industrial-size CFBs that use different types of low-grade fuels given in the literature. The present study proves that CFB combustion demonstrated by both experimental data and model predictions produces low and acceptable levels of NOx emissions resulting from the combustion of low-grade fuels. Developed model can also investigate the effects of different operational parameters on overall NOx emission. As a result of this investigation, both experimental data and model predictions show that NOx emission increases with the bed temperature but decreases with excess air if other parameters are kept unchanged. 37 refs., 5 figs., 5 tabs.
Bozeman, Jeffrey; Chen, Kuo-Huey
2014-12-09
On November 3, 2009, General Motors (GM) accepted U.S. Department of Energy (DOE) Cooperative Agreement award number DE-EE0000014 from the National Energy Technology Laboratory (NETL). GM was selected to execute a three-year cost shared research and development project on Solid State Energy Conversion for Vehicular Heating, Ventilation & Air Conditioning (HVAC) and for Waste Heat Recovery.
Single-Column Modeling R. D. Cess Marine Sciences Research Center
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D. Cess Marine Sciences Research Center State University of New York Stony Brook, NY 11794-5000 Cloud-climate interactions are one of the greatest uncertainties in contemporary general circulation models (GCMs) (Cess et al. 1989, 1990), and the present study has focused on one aspect of this. Specifically, combined satellite and near-surface shortwave (SW) flux measurements have been used to test the impact of clouds on the SW radiation budget of two GCMs. Concentration is initially on SW rather
Methods of forming a fluidized bed of circulating particles
Marshall, Douglas W.
2011-05-24
There is disclosed an apparatus for forming a fluidized bed of circulating particles. In an embodiment, the apparatus includes a bottom portion having a sidewall, the sidewall defining a curvilinear profile, and the bottom portion configured to contain a bed of particles; and a gas inlet configured to produce a column of gas to carry entrained particles therein. There is disclosed a method of forming a fluidized bed of circulating particles. In an embodiment, the method includes positioning particles within a bottom portion having a sidewall, the sidewall defining a curvilinear profile; producing a column of gas directed upwardly through a gas inlet; carrying entrained particles in the column of gas to produce a fountain of particles over the fluidized bed of circulating particles and subside in the particle bed until being directed inwardly into the column of gas within the curvilinear profile.
Recent progress on Exxon's circulating zinc bromine battery system
Bellows, R.J.
1981-01-01
The design, performance, and factory cost of Exxon's circulating zinc bromine batteries are described. The Exxon system has demonstrated stable performance in scale-ups to 3- and 10-kWh sub-modules. Cost studies based on recently demonstrated extrusion and injection molding techniques, have shown that this battery, with plastic electrodes, bipolar stacks, Br/sub 2/ complexation, and circulating electrolytes, could be produced (20 kWh units, 100,000 units/year) at a factory cost of $28/kWh (excluding R.O.I., and various indirect overheads).
General | Open Energy Information
General Jump to: navigation, search Informacin y Documentos Herramientas y Modelos <> Estadsticas de Energas Renovables Volver Pgina principal General banner.jpg Retrieved...
Amy Honchar
2012-11-12
The contribution of funds from DOE supported publication costs of a special issue of Deep Sea Research arising from presentations at the First U.S. Atlantic Meridional Overturning Circulation (AMOC) Meeting held 4-6 May, 2009 to review the US implementation plan and its coordination with other monitoring activities. The special issue includes a total of 16 papers, including publications from three DOE-supported investigators (ie Sevellec, F., and A.V. Fedorov; Hu et. al., and Wan et. al.,). The special issue addresses DOE interests in understanding and simulation/modeling of abrupt climate change.
Viscosity of liquid {sup 4}He and quantum of circulation: Are they related?
L’vov, Victor S. E-mail: skrbek@fzu.cz; Skrbek, Ladislav E-mail: skrbek@fzu.cz; Sreenivasan, Katepalli R. E-mail: skrbek@fzu.cz
2014-04-15
In the vicinity of the superfluid transition in liquid {sup 4}He, we explore the relation between two apparently unrelated physical quantities—the kinematic viscosity, ν, in the normal state and the quantum of circulation, κ, in the superfluid state. The model developed here leads to the simple relationship ν ≈ κ/6, and links the classical and quantum flow properties of liquid {sup 4}He. We critically examine available data relevant to this relation and find that the prediction holds well at the saturated vapor pressure. Additionally, we predict the kinematic viscosity for liquid {sup 4}He along the λ-line at negative pressures.
Development of a Multi Megawatt Circulator for X Band
Neilson, J.; Ives, L.; Tantawi, S.G.; /Calabazas Creek Res., Saratoga /SLAC
2008-03-24
Research is in progress on a TeV-scale linear collider that will operate at 5-10 times the energy of present-generation accelerators. This will require development of high power RF sources generating of 50-100 MW per source. Transmission of power at this level requires overmoded waveguide to avoid breakdown. In particular, the TE{sub 01} circular waveguide mode is currently the mode of choice for waveguide transmission at Stanford Linear Accelerator Center (SLAC) in the Multimode Delay Line Distribution System (MDLDS). A common device for protecting an RF source from reflected power is the waveguide circulator. A circulator is typically a three-port device that allows low loss power transmission from the source to the load, but diverts power coming from the load (reflected power) to a third terminated port. To achieve a low loss, matched, three port junction requires nonreciprocal behavior. This is achieved using ferrites in a static magnetic field which introduces a propagation constant dependent on RF field direction relative to the static magnetic field. Circulators are currently available at X-Band for power levels up to 1 MW in fundamental rectangular waveguide; however, the next generation of RF sources for TeV-level accelerators will require circulators in the 50-100 MW range. Clearly, conventional technology is not capable of reaching the power level required. In this paper, we discuss the development of an X-Band circulator operating at multi-megawatt power levels in overmoded waveguide. The circulator will employ an innovative coaxial geometry using the TE{sub 01} mode. Difficulties in maintaining mode purity in oversized rectangular guide preclude increasing guide area to allow increasing the power level to the desired 50-100 MW range. The TE{sub 01} mode in circular waveguide is very robust mode for transmission of high power in overmoded waveguide. The mode is ideal for transmission of high power microwaves because of its low-losses, zero tangential
Generalized Cartan Calculus in general dimension
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Wang, Yi -Nan
2015-07-22
We develop the generalized Cartan Calculus for the groups G = SL(2,R) × R+, SL(5,R) and SO(5,5). They are the underlying algebraic structures of d=9,7,6 exceptional field theory, respectively. These algebraic identities are needed for the "tensor hierarchy" structure in exceptional field theory. The validity of Poincar\\'e lemmas in this new differential geometry is also discussed. Lastly, we explore some possible extension of the generalized Cartan calculus beyond the exceptional series.
General Merchandise 50% Energy Savings Technical Support Document...
Publication Year 2009 URL http:www.nrel.govdocsfy09osti46100.pdf Building Models General Merchandise 2009 TSD Chicago High Plug Load Baseline, General Merchandise 2009...
Entanglement Entropy of the Early Universe in Generalized Chaplygin...
Office of Scientific and Technical Information (OSTI)
Entanglement Entropy of the Early Universe in Generalized Chaplygin Gas Model Citation Details In-Document Search Title: Entanglement Entropy of the Early Universe in Generalized...
MFIX simulation of NETL/PSRI challenge problem of circulating fluidized bed
Li, Tingwen; Dietiker, Jean-Franois; Shahnam, Mehrdad
2012-12-01
In this paper, numerical simulations of NETL/PSRI challenge problem of circulating fluidized bed (CFB) using the open-source code Multiphase Flow with Interphase eXchange (MFIX) are reported. Two rounds of simulation results are reported including the first-round blind test and the second-round modeling refinement. Three-dimensional high fidelity simulations are conducted to model a 12-inch diameter pilot-scale CFB riser. Detailed comparisons between numerical results and experimental data are made with respect to axial pressure gradient profile, radial profiles of solids velocity and solids mass flux along different radial directions at various elevations for operating conditions covering different fluidization regimes. Overall, the numerical results show that CFD can predict the complex gassolids flow behavior in the CFB riser reasonably well. In addition, lessons learnt from modeling this challenge problem are presented.
MFIX simulation of NETL/PSRI challenge problem of circulating fluidized bed
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Li, Tingwen; Dietiker, Jean-François; Shahnam, Mehrdad
2012-12-01
In this paper, numerical simulations of NETL/PSRI challenge problem of circulating fluidized bed (CFB) using the open-source code Multiphase Flow with Interphase eXchange (MFIX) are reported. Two rounds of simulation results are reported including the first-round blind test and the second-round modeling refinement. Three-dimensional high fidelity simulations are conducted to model a 12-inch diameter pilot-scale CFB riser. Detailed comparisons between numerical results and experimental data are made with respect to axial pressure gradient profile, radial profiles of solids velocity and solids mass flux along different radial directions at various elevations for operating conditions covering different fluidization regimes. Overall, the numericalmore » results show that CFD can predict the complex gas–solids flow behavior in the CFB riser reasonably well. In addition, lessons learnt from modeling this challenge problem are presented.« less
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Table for 5Li is subdivided into the folowing categories: Ground State Properties Cluster Model Shell Model Special States Model Calculations Model Discussions Complex...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
following categories: Ground State Properties Theoretical Special States Shell Model Cluster and alpha-particle Models Other Models Model Calculations Complex Reactions Involving...
Vigil,Benny Manuel; Ballance, Robert; Haskell, Karen
2012-08-09
Cielo is a massively parallel supercomputer funded by the DOE/NNSA Advanced Simulation and Computing (ASC) program, and operated by the Alliance for Computing at Extreme Scale (ACES), a partnership between Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL). The primary Cielo compute platform is physically located at Los Alamos National Laboratory. This Cielo Computational Environment Usage Model documents the capabilities and the environment to be provided for the Q1 FY12 Level 2 Cielo Capability Computing (CCC) Platform Production Readiness Milestone. This document describes specific capabilities, tools, and procedures to support both local and remote users. The model is focused on the needs of the ASC user working in the secure computing environments at Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory, or Sandia National Laboratories, but also addresses the needs of users working in the unclassified environment. The Cielo Computational Environment Usage Model maps the provided capabilities to the tri-Lab ASC Computing Environment (ACE) Version 8.0 requirements. The ACE requirements reflect the high performance computing requirements for the Production Readiness Milestone user environment capabilities of the ASC community. A description of ACE requirements met, and those requirements that are not met, are included in each section of this document. The Cielo Computing Environment, along with the ACE mappings, has been issued and reviewed throughout the tri-Lab community.
Apparatus and method for determining solids circulation rate
Ludlow, J. Christopher; Spenik, James L.
2012-02-14
The invention relates to a method of determining bed velocity and solids circulation rate in a standpipe experiencing a moving packed bed flow, such as the in the standpipe section of a circulating bed fluidized reactor The method utilizes in-situ measurement of differential pressure over known axial lengths of the standpipe in conjunction with in-situ gas velocity measurement for a novel application of Ergun equations allowing determination of standpipe void fraction and moving packed bed velocity. The method takes advantage of the moving packed bed property of constant void fraction in order to integrate measured parameters into simultaneous solution of Ergun-based equations and conservation of mass equations across multiple sections of the standpipe.
Liquid Fluoride Salt Experimentation Using a Small Natural Circulation Cell
Yoder Jr, Graydon L; Heatherly, Dennis Wayne; Williams, David F; Elkassabgi, Yousri M.; Caja, Joseph; Caja, Mario; Jordan, John; Salinas, Roberto
2014-04-01
A small molten fluoride salt experiment has been constructed and tested to develop experimental techniques for application in liquid fluoride salt systems. There were five major objectives in developing this test apparatus: Allow visual observation of the salt during testing (how can lighting be introduced, how can pictures be taken, what can be seen) Determine if IR photography can be used to examine components submerged in the salt Determine if the experimental configuration provides salt velocity sufficient for collection of corrosion data for future experimentation Determine if a laser Doppler velocimeter can be used to quantify salt velocities. Acquire natural circulation heat transfer data in fluoride salt at temperatures up to 700oC All of these objectives were successfully achieved during testing with the exception of the fourth: acquiring velocity data using the laser Doppler velocimeter. This paper describes the experiment and experimental techniques used, and presents data taken during natural circulation testing.
Easter, R.C.; Hales, J.M.
1984-11-01
This report is a second-edition user's manual for the PLUVIUS reactive-storm model. The PLUVIUS code simulates the formation of storm systems of a variety of types, and characterizes the behavior of air pollutants as they flow through, react within, and are scavenged by the storms. The computer code supplied with this report is known as PLUVIUS MOD 5.0, and is a substantial improvement over the MOD 3.1 version given in the original user's manual. Example applications of MOD 5.0 are given in the report to facilitate rapid application of the code for a variety of specific uses. 22 references, 7 figures, 48 tables.
General Employee Radiological Training
Broader source: Energy.gov (indexed) [DOE]
Part 2 page 5 The average annual radiation dose to a member of the general population is about 360 milliremyear. The average annual radiation dose to a member of the general ...
Karami, K.
2010-01-01
Author of ref. 1, M.R. Setare (JCAP 01 (2007) 023), by redefining the event horizon measured from the sphere of the horizon as the system's IR cut-off for an interacting holographic dark energy model in a non-flat universe, showed that the generalized second law of thermodynamics is satisfied for the special range of the deceleration parameter. His paper includes an erroneous calculation of the entropy of the cold dark matter. Also there are some missing terms and some misprints in the equations of his paper. Here we present that his conclusion is not true and the generalized second law is violated for the present time independently of the deceleration parameter.
White, L.S.
1990-07-01
This report presents the results of a study of the lessons learned during the design, testing, and operation of gas-cooled reactor coolant circulators. The intent of this study is to identify failure modes and problem areas of the existing circulators so this information can be incorporated into the design of the circulators for the New Production Reactor (NPR)-Modular High-Temperature Gas Cooled Reactor (MHTGR). The information for this study was obtained primarily from open literature and includes data on high-pressure, high-temperature helium test loop circulators as well as the existing gas cooled reactors worldwide. This investigation indicates that trouble free circulator performance can only be expected when the design program includes a comprehensive prototypical test program, with the results of this test program factored into the final circulator design. 43 refs., 7 tabs.
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
APP-005 Planning for and Measuring Office of Inspector General Results FY 2002 Annual Performance Report and FY 2003 Annual Performance Plan Office of Inspector General U.S. Department of Energy Inspector General's Message We are pleased to present the Office of Inspector General's (OIG) consolidated Fiscal Year 2002 Annual Performance Report and Fiscal Year 2003 Annual Performance Plan. This document evaluates our actual Fiscal Year (FY) 2002 performance and establishes the performance goals
Generalized Cartan Calculus in general dimension
Wang, Yi -Nan
2015-07-22
We develop the generalized Cartan Calculus for the groups G = SL(2,R) × R^{+}, SL(5,R) and SO(5,5). They are the underlying algebraic structures of d=9,7,6 exceptional field theory, respectively. These algebraic identities are needed for the "tensor hierarchy" structure in exceptional field theory. The validity of Poincar\\'e lemmas in this new differential geometry is also discussed. Lastly, we explore some possible extension of the generalized Cartan calculus beyond the exceptional series.
Parametric study of natural circulation flow in molten salt fuel in molten salt reactor
Pauzi, Anas Muhamad; Cioncolini, Andrea; Iacovides, Hector
2015-04-29
The Molten Salt Reactor (MSR) is one of the most promising system proposed by Generation IV Forum (GIF) for future nuclear reactor systems. Advantages of the MSR are significantly larger compared to other reactor system, and is mainly achieved from its liquid nature of fuel and coolant. Further improvement to this system, which is a natural circulating molten fuel salt inside its tube in the reactor core is proposed, to achieve advantages of reducing and simplifying the MSR design proposed by GIF. Thermal hydraulic analysis on the proposed system was completed using a commercial computation fluid dynamics (CFD) software called FLUENT by ANSYS Inc. An understanding on theory behind this unique natural circulation flow inside the tube caused by fission heat generated in molten fuel salt and tube cooling was briefly introduced. Currently, no commercial CFD software could perfectly simulate natural circulation flow, hence, modeling this flow problem in FLUENT is introduced and analyzed to obtain best simulation results. Results obtained demonstrate the existence of periodical transient nature of flow problem, hence improvements in tube design is proposed based on the analysis on temperature and velocity profile. Results show that the proposed system could operate at up to 750MW core power, given that turbulence are enhanced throughout flow region, and precise molten fuel salt physical properties could be defined. At the request of the authors and the Proceedings Editor the name of the co-author Andrea Cioncolini was corrected from Andrea Coincolini. The same name correction was made in the Acknowledgement section on page 030004-10 and in reference number 4. The updated article was published on 11 May 2015.
A toolkit for building earth system models
Foster, I.
1993-03-01
An earth system model is a computer code designed to simulate the interrelated processes that determine the earth's weather and climate, such as atmospheric circulation, atmospheric physics, atmospheric chemistry, oceanic circulation, and biosphere. I propose a toolkit that would support a modular, or object-oriented, approach to the implementation of such models.
A toolkit for building earth system models
Foster, I.
1993-03-01
An earth system model is a computer code designed to simulate the interrelated processes that determine the earth`s weather and climate, such as atmospheric circulation, atmospheric physics, atmospheric chemistry, oceanic circulation, and biosphere. I propose a toolkit that would support a modular, or object-oriented, approach to the implementation of such models.
Daleu, C. L.; Plant, R. S.; Woolnough, S. J.; Sessions, S.; Herman, M. J.; Sobel, A.; Wang, S.; Kim, D.; Cheng, A.; Bellon, G.; Peyrille, P.; Ferry, F.; Siebesma, P.; van Ulft, L.
2015-10-24
Here, as part of an international intercomparison project, a set of single-column models (SCMs) and cloud-resolving models (CRMs) are run under the weak-temperature gradient (WTG) method and the damped gravity wave (DGW) method. For each model, the implementation of the WTG or DGW method involves a simulated column which is coupled to a reference state defined with profiles obtained from the same model in radiative-convective equilibrium. The simulated column has the same surface conditions as the reference state and is initialized with profiles from the reference state. We performed systematic comparison of the behavior of different models under a consistent implementation of the WTG method and the DGW method and systematic comparison of the WTG and DGW methods in models with different physics and numerics. CRMs and SCMs produce a variety of behaviors under both WTG and DGW methods. Some of the models reproduce the reference state while others sustain a large-scale circulation which results in either substantially lower or higher precipitation compared to the value of the reference state. CRMs show a fairly linear relationship between precipitation and circulation strength. SCMs display a wider range of behaviors than CRMs. Some SCMs under the WTG method produce zero precipitation. Within an individual SCM, a DGW simulation and a corresponding WTG simulation can produce different signed circulation. When initialized with a dry troposphere, DGW simulations always result in a precipitating equilibrium state. The greatest sensitivities to the initial moisture conditions occur for multiple stable equilibria in some WTG simulations, corresponding to either a dry equilibrium state when initialized as dry or a precipitating equilibrium state when initialized as moist. Multiple equilibria are seen in more WTG simulations for higher SST. In some models, the existence of multiple equilibria is sensitive to some parameters in the WTG calculations.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Daleu, C. L.; Plant, R. S.; Woolnough, S. J.; Sessions, S.; Herman, M. J.; Sobel, A.; Wang, S.; Kim, D.; Cheng, A.; Bellon, G.; et al
2015-10-24
Here, as part of an international intercomparison project, a set of single-column models (SCMs) and cloud-resolving models (CRMs) are run under the weak-temperature gradient (WTG) method and the damped gravity wave (DGW) method. For each model, the implementation of the WTG or DGW method involves a simulated column which is coupled to a reference state defined with profiles obtained from the same model in radiative-convective equilibrium. The simulated column has the same surface conditions as the reference state and is initialized with profiles from the reference state. We performed systematic comparison of the behavior of different models under a consistentmore » implementation of the WTG method and the DGW method and systematic comparison of the WTG and DGW methods in models with different physics and numerics. CRMs and SCMs produce a variety of behaviors under both WTG and DGW methods. Some of the models reproduce the reference state while others sustain a large-scale circulation which results in either substantially lower or higher precipitation compared to the value of the reference state. CRMs show a fairly linear relationship between precipitation and circulation strength. SCMs display a wider range of behaviors than CRMs. Some SCMs under the WTG method produce zero precipitation. Within an individual SCM, a DGW simulation and a corresponding WTG simulation can produce different signed circulation. When initialized with a dry troposphere, DGW simulations always result in a precipitating equilibrium state. The greatest sensitivities to the initial moisture conditions occur for multiple stable equilibria in some WTG simulations, corresponding to either a dry equilibrium state when initialized as dry or a precipitating equilibrium state when initialized as moist. Multiple equilibria are seen in more WTG simulations for higher SST. In some models, the existence of multiple equilibria is sensitive to some parameters in the WTG calculations.« less
Gidaspow, D.; Ettehadieh, B.; Lin, C.; Goyal, A.; Lyczkowski, R.W.
1980-01-01
The object of this investigation was to develop an experimentally verified hydrodynamic model to predict solids circulation around a jet in a fluidized bed gasifier. Hydrodynamic models of fluidization use the principles of conservation of mass, momentum and energy. To account for unequal velocities of solid and fluid phases, separate phase momentum balances are developed. Other fluid bed models used in the scale-up of gasifiers do not employ the principles of conservation of momentum. Therefore, these models cannot predict fluid and particle motion. In such models solids mixing is described by means of empirical transfer coefficients. A two dimensional unsteady state computer code was developed to give gas and solid velocities, void fractions and pressure in a fluid bed with a jet. The growth, propagation and collapse of bubbles was calculated. Time-averaged void fractions were calculated that showed an agreement with void fractions measured with a gamma ray densitometer. Calculated gas and solid velocities in the jet appeared to be reasonable. Pressure and void oscillations also appear to be reasonable. A simple analytical formula for the rate of solids circulation was developed from the equations of change. It agrees with Westinghouse fluidization data in a bed with a draft tube. One dimensional hydrodynamic models were applied to modeling of entrained-flow coal gasification reactors and compared with data. Further development of the hydrodynamic models should make the scale-up and simulation of fluidized bed reactors a reality.
Fedorov, Alexey
2013-11-23
The central goal of this research project is to understand the properties of the ocean meridional overturning circulation (MOC) – a topic critical for understanding climate variability and stability on a variety of timescales (from decadal to centennial and longer). Specifically, we have explored various factors that control the MOC stability and decadal variability in the Atlantic and the ocean thermal structure in general, including the possibility abrupt climate change. We have also continued efforts on improving the performance of coupled ocean-atmosphere GCMs.
Rhee, B. W.; Ha, K. S.; Park, R. J.; Song, J. H.
2012-07-01
In this paper, a study on the effect of various design parameters such as the channel gap width, heat flux distribution, down-comer pipe size and two-phase flow slip ratio on the natural circulation flow rate is performed based on a physical model for a natural circulation flow along the flow path of the ex-vessel core catcher cooling system of an EU-APR1400, and these effects on the natural circulation flow rate are analyzed and compared with the minimum flow rate required for the safe operation of the system. (authors)
Predictive Understanding of the Oceans' Wind-Driven Circulation on Interdecadal Time Scales
Michael Ghil; Temam, Roger; Y. Feliks; Simonnet, E.; Tachim-Medjo, T.
2008-09-30
The goal of this project was to obtain a predictive understanding of a major component of the climate system's interdecadal variability: the oceans' wind-driven circulation. To do so, we developed and applied advanced computational and statistical methods to the problem of climate variability and climate change. The methodology was developed first for models of intermediate complexity, such as the quasi-geostrophic and the primitive equations, which describe the wind-driven, near-surface flow in mid-latitude ocean basins. Our computational work consisted in developing efficient multi-level methods to simulate this flow and study its dependence on physically relevant parameters. Our oceanographic and climate work consisted in applying these methods to study the bifurcations in the wind-driven circulation and their relevance to the flows observed at present and those that might occur in a warmer climate. Both aspects of the work are crucial for the efficient treatment of large-scale, eddy-resolving numerical simulations of the oceans and an increased understanding and better prediction of climate change. Considerable progress has been achieved in understanding ocean-atmosphere interaction in the mid-latitudes. An important by-product of this research is a novel approach to explaining the North Atlantic Oscillation.
Vogelmann, A. M.
2004-01-27
OAK-B135 Final report from the University of California San Diego for an ongoing research project that was moved to Brookhaven National Laboratory where proposed work will be completed. The research uses measurements made by the Atmospheric Radiation Measurement (ARM) Program to quantify the effects of aerosols and clouds on the Earth's energy balance in the climatically important Tropical Western Pacific.
A Structural Model Guide For Geothermal Exploration In Ancestral...
traverse the base of the AMB volcano. This master fault induced fracture-controlled permeability where fluids in the Tongonan Geothermal Field circulate. The structural model...
Regional Climate Modeling: Progress, Challenges, and Prospects
Wang, Yuqing; Leung, Lai R.; McGregor, John L.; Lee, Dong-Kyou; Wang, Wei-Chyung; Ding, Yihui; Kimura, Fujio
2004-12-01
Regional climate modeling with regional climate models (RCMs) has matured over the past decade and allows for meaningful utilization in a broad spectrum of applications. In this paper, latest progresses in regional climate modeling studies are reviewed, including RCM development, applications of RCMs to dynamical downscaling for climate change assessment, seasonal climate predictions and climate process studies, and the study of regional climate predictability. Challenges and potential directions of future research in this important area are discussed, with the focus on those to which less attention has been given previously, such as the importance of ensemble simulations, further development and improvement of regional climate modeling approach, modeling extreme climate events and sub-daily variation of clouds and precipitation, model evaluation and diagnostics, applications of RCMs to climate process studies and seasonal predictions, and development of regional earth system models. It is believed that with both the demonstrated credibility of RCMs capability in reproducing not only monthly to seasonal mean climate and interannual variability but also the extreme climate events when driven by good quality reanalysis and the continuous improvements in the skill of global general circulation models (GCMs) in simulating large-scale atmospheric circulation, regional climate modeling will remain an important dynamical downscaling tool for providing the needed information for assessing climate change impacts and seasonal climate predictions, and a powerful tool for improving our understanding of regional climate processes. An internationally coordinated effort can be developed with different focuses by different groups to advance regional climate modeling studies. It is also recognized that since the final quality of the results from nested RCMs depends in part on the realism of the large-scale forcing provided by GCMs, the reduction of errors and improvement in
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
General User Proposals (GUPs) General User Proposals (GUPs) Print Tuesday, 01 June 2010 09:36 General Users are granted beam time through a peer review proposal process. They may use beamlines and endstations provided by the ALS or the Participating Research Team (PRT) that operates the beamline. Before Submitting a Proposal Review the ALS Beamlines Directory to learn about the research capabilities of individual beamlines at the ALS. Contact the beamline scientist or the local contact listed in
The generalized SchrdingerLangevin equation
Bargueo, Pedro; Miret-Arts, Salvador
2014-07-15
In this work, for a Brownian particle interacting with a heat bath, we derive a generalization of the so-called SchrdingerLangevin or Kostin equation. This generalization is based on a nonlinear interaction model providing a state-dependent dissipation process exhibiting multiplicative noise. Two straightforward applications to the measurement process are then analyzed, continuous and weak measurements in terms of the quantum Bohmian trajectory formalism. Finally, it is also shown that the generalized uncertainty principle, which appears in some approaches to quantum gravity, can be expressed in terms of this generalized equation. -- Highlights: We generalize the Kostin equation for arbitrary systembath coupling. This generalization is developed both in the Schrdinger and Bohmian formalisms. We write the generalized Kostin equation for two measurement problems. We reformulate the generalized uncertainty principle in terms of this equation.
2012-04-01
Solid-state lighting program technology fact sheet that compares general service incandescent lamps—i.e., light bulbs—to LED and CFL alternatives.
Broader source: Energy.gov [DOE]
A U.S. DOE SSL technology fact sheet that compares general service LED light bulbs with incandescent and CFL bulbs.
QUANTUM MECHANICS, GENERAL PHYSICS; 74 ATOMIC AND MOLECULAR PHYSICS...
Office of Scientific and Technical Information (OSTI)
of model atoms in fields Milonni, P.W. 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 74 ATOMIC AND MOLECULAR PHYSICS; ATOMS; OPTICAL MODELS; QUANTUM MECHANICS;...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
subdivided into the following categories: Reviews Ground State Properties Shell Model Cluster Model Other Theoretical Work Complex Reactions Reactions Involving Pions, Other...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
for 10C is subdivided into the following categories: Reviews Ground State Properties Shell Model Cluster Model Other Theoretical Work Photodisintegration b-decay Complex Reactions...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
9Be is subdivided into the following categories: Ground State Properties Shell Model Cluster Model Theoretical Complex Reactions Beta-Decay Light-Ion and Neutron Induced...