WorldWideScience

Sample records for surface model l4

  1. NLDAS Mosaic Land Surface Model L4 Hourly 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Mosaic land-surface model (LSM) for Phase 2 of the North American Land Data...

  2. NLDAS VIC Land Surface Model L4 Hourly 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC land-surface model (LSM) for Phase 2 of the North American Land Data Assimilation...

  3. NLDAS Noah Land Surface Model L4 Monthly 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah land-surface model (LSM) for Phase 2 of the North American Land Data Assimilation...

  4. NLDAS Mosaic Land Surface Model L4 Monthly Climatology 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This monthly climatology data set contains a series of land surface parameters simulated from the Mosaic land-surface model (LSM) for Phase 2 of the North American...

  5. NLDAS Mosaic Land Surface Model L4 Monthly 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Mosaic land-surface model (LSM) for Phase 2 of the North American Land Data...

  6. NLDAS VIC Land Surface Model L4 Monthly 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC land-surface model (LSM) for Phase 2 of the North American Land Data Assimilation...

  7. NLDAS Noah Land Surface Model L4 Monthly Climatology 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This monthly climatology data set contains a series of land surface parameters simulated from the Noah land-surface model (LSM) for Phase 2 of the North American...

  8. NLDAS VIC Land Surface Model L4 Monthly Climatology 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract: This data set contains a series of land surface parameters simulated from the VIC land-surface model (LSM) for Phase 2 of the North American Land Data...

  9. NLDAS Noah Land Surface Model L4 Hourly 0.125 x 0.125 degree V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah land-surface model (LSM) for Phase 2 of the North American Land Data Assimilation...

  10. GLDAS CLM Land Surface Model L4 Monthly 1.0 x 1.0 degree V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Common Land Model (CLM) V2.0 model in the Global Land Data Assimilation System (GLDAS)....

  11. GLDAS CLM Land Surface Model L4 3 Hourly 1.0 x 1.0 degree Subsetted V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Common Land Model (CLM) V2.0 model in the Global Land Data Assimilation System (GLDAS)....

  12. GLDAS Noah Land Surface Model L4 3 Hourly 1.0 x 1.0 degree Subsetted V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 2.7.1 model in the Global Land Data Assimilation System (GLDAS). The data are in...

  13. GLDAS VIC Land Surface Model L4 3 Hourly 1.0 x 1.0 degree V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Variable Infiltration Capacity (VIC) Model in the Global Land Data Assimilation System...

  14. GLDAS Mosaic Land Surface Model L4 3 Hourly 1.0 x 1.0 degree Subsetted V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Mosaic model in the Global Land Data Assimilation System (GLDAS). The data are in 1.0...

  15. GLDAS Noah Land Surface Model L4 Monthly 1.0 x 1.0 degree V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 2.7.1 model in the Global Land Data Assimilation System (GLDAS). The data are in...

  16. GLDAS Mosaic Land Surface Model L4 Monthly 1.0 x 1.0 degree V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Mosaic model in the Global Land Data Assimilation System (GLDAS). The data are in 1.0...

  17. GLDAS Noah Land Surface Model L4 Monthly 0.25 x 0.25 degree V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 2.7.1 model in the Global Land Data Assimilation System (GLDAS). The data are in...

  18. GLDAS Noah Land Surface Model L4 3 Hourly 0.25 x 0.25 degree Subsetted V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 2.7.1 model in the Global Land Data Assimilation System (GLDAS). The data are in...

  19. GLDAS VIC Land Surface Model L4 Monthly 1.0 x 1.0 degree V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Variable Infiltration Capacity (VIC) model in the Global Land Data Assimilation System...

  20. NLDAS VIC Land Surface Model L4 Monthly Climatology 0.125 x 0.125 degree V002 (NLDAS_VIC0125_MC) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract: This data set contains a series of land surface parameters simulated from the VIC land-surface model (LSM) for Phase 2 of the North American Land Data...

  1. NLDAS Mosaic Land Surface Model L4 Monthly Climatology 0.125 x 0.125 degree V002 (NLDAS_MOS0125_MC) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This monthly climatology data set contains a series of land surface parameters simulated from the Mosaic land-surface model (LSM) for Phase 2 of the North American...

  2. NLDAS Noah Land Surface Model L4 Hourly 0.125 x 0.125 degree V002 (NLDAS_NOAH0125_H) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah land-surface model (LSM) for Phase 2 of the North American Land Data Assimilation...

  3. NLDAS Mosaic Land Surface Model L4 Hourly 0.125 x 0.125 degree V002 (NLDAS_MOS0125_H) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Mosaic land-surface model (LSM) for Phase 2 of the North American Land Data...

  4. The SMAP Level 4 Surface and Root-zone Soil Moisture (L4_SM) Product

    Science.gov (United States)

    Reichle, Rolf; Crow, Wade; Koster, Randal; Kimball, John

    2010-01-01

    that are informed by and consistent with SMAP observations. Such estimates are obtained by merging SMAP observations with estimates from a land surface model in a soil moisture data assimilation system. The land surface model component of the assimilation system is driven with observations-based surface meteorological forcing data, including precipitation, which is the most important driver for soil moisture. The model also encapsulates knowledge of key land surface processes, including the vertical transfer of soil moisture between the surface and root zone reservoirs. Finally, the model interpolates and extrapolates SMAP observations in time and in space. The L4_SM product thus provides a comprehensive and consistent picture of land surface hydrological conditions based on SMAP observations and complementary information from a variety of sources. The assimilation algorithm considers the respective uncertainties of each component and yields a product that is superior to satellite or model data alone. Error estimates for the L4_SM product are generated as a by-product of the data assimilation system.

  5. LPJmL4 - a dynamic global vegetation model with managed land - Part 1: Model description

    Science.gov (United States)

    Schaphoff, Sibyll; von Bloh, Werner; Rammig, Anja; Thonicke, Kirsten; Biemans, Hester; Forkel, Matthias; Gerten, Dieter; Heinke, Jens; Jägermeyr, Jonas; Knauer, Jürgen; Langerwisch, Fanny; Lucht, Wolfgang; Müller, Christoph; Rolinski, Susanne; Waha, Katharina

    2018-04-01

    This paper provides a comprehensive description of the newest version of the Dynamic Global Vegetation Model with managed Land, LPJmL4. This model simulates - internally consistently - the growth and productivity of both natural and agricultural vegetation as coherently linked through their water, carbon, and energy fluxes. These features render LPJmL4 suitable for assessing a broad range of feedbacks within and impacts upon the terrestrial biosphere as increasingly shaped by human activities such as climate change and land use change. Here we describe the core model structure, including recently developed modules now unified in LPJmL4. Thereby, we also review LPJmL model developments and evaluations in the field of permafrost, human and ecological water demand, and improved representation of crop types. We summarize and discuss LPJmL model applications dealing with the impacts of historical and future environmental change on the terrestrial biosphere at regional and global scale and provide a comprehensive overview of LPJmL publications since the first model description in 2007. To demonstrate the main features of the LPJmL4 model, we display reference simulation results for key processes such as the current global distribution of natural and managed ecosystems, their productivities, and associated water fluxes. A thorough evaluation of the model is provided in a companion paper. By making the model source code freely available at https://gitlab.pik-potsdam.de/lpjml/LPJmL, we hope to stimulate the application and further development of LPJmL4 across scientific communities in support of major activities such as the IPCC and SDG process.

  6. FLDAS VIC Land Surface Model L4 monthly 0.25 x 0.25 degree for Western Africa (MERRA-2 and CHIRPS) V001 (FLDAS_VIC025_C_WA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  7. FLDAS Noah Land Surface Model L4 monthly 0.1 x 0.1 degree for Eastern Africa (MERRA-2 and CHIRPS) V001 (FLDAS_NOAH01_C_EA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  8. FLDAS Noah Land Surface Model L4 monthly 0.1 x 0.1 degree for Southern Africa (MERRA-2 and CHIRPS) V001 (FLDAS_NOAH01_C_SA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  9. FLDAS Noah Land Surface Model L4 monthly 0.1 x 0.1 degree for Western Africa (MERRA-2 and CHIRPS) V001 (FLDAS_NOAH01_C_WA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  10. FLDAS VIC Land Surface Model L4 monthly 0.25 x 0.25 degree for Southern Africa (MERRA-2 and CHIRPS) V001 (FLDAS_VIC025_C_SA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  11. FLDAS Noah Land Surface Model L4 daily 0.1 x 0.1 degree for Eastern Africa (GDAS and RFE2) V001 (FLDAS_NOAH01_A_EA_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  12. FLDAS VIC Land Surface Model L4 monthly 0.25 x 0.25 degree for Southern Africa (GDAS and RFE2) V001 (FLDAS_VIC025_A_SA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  13. FLDAS VIC Land Surface Model L4 monthly 0.25 x 0.25 degree for Eastern Africa (MERRA-2 and CHIRPS) V001 (FLDAS_VIC025_C_EA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  14. FLDAS Noah Land Surface Model L4 Monthly Climatology 0.1 x 0.1 degree for Eastern Africa (MERRA-2 and CHIRPS) V001 (FLDAS_NOAH01_C_EA_MC) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The monthly climatology data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS...

  15. FLDAS Noah Land Surface Model L4 daily 0.1 x 0.1 degree for Southern Africa (GDAS and RFE2) V001 (FLDAS_NOAH01_A_SA_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  16. FLDAS Noah Land Surface Model L4 monthly 0.1 x 0.1 degree for Western Africa (GDAS and RFE2) V001 (FLDAS_NOAH01_A_WA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  17. FLDAS VIC Land Surface Model L4 daily 0.25 x 0.25 degree for Western Africa (GDAS and RFE2) V001 (FLDAS_VIC025_A_WA_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  18. FLDAS VIC Land Surface Model L4 monthly 0.25 x 0.25 degree for Eastern Africa (GDAS and RFE2) V001 (FLDAS_VIC025_A_EA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  19. FLDAS VIC Land Surface Model L4 daily 0.25 x 0.25 degree for Eastern Africa (GDAS and RFE2) V001 (FLDAS_VIC025_A_EA_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  20. FLDAS VIC Land Surface Model L4 monthly 0.25 x 0.25 degree for Western Africa (GDAS and RFE2) V001 (FLDAS_VIC025_A_WA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  1. FLDAS VIC Land Surface Model L4 Daily 0.25 x 0.25 degree for Southern Africa (MERRA-2 and CHIRPS) V001 (FLDAS_VIC025_A_SA_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the VIC model in the Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation...

  2. FLDAS Noah Land Surface Model L4 daily 0.1 x 0.1 degree for Western Africa (GDAS and RFE2) V001 (FLDAS_NOAH01_A_WA_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  3. FLDAS Noah Land Surface Model L4 monthly 0.1 x 0.1 degree for Eastern Africa (GDAS and RFE2) V001 (FLDAS_NOAH01_A_EA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  4. FLDAS Noah Land Surface Model L4 monthly 0.1 x 0.1 degree for Southern Africa (GDAS and RFE2) V001 (FLDAS_NOAH01_A_SA_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a series of land surface parameters simulated from the Noah 3.3 model in the Famine Early Warning Systems Network (FEWS NET) Land Data...

  5. Comparative morphometry of L4 vertebrae: comparison of large animal models for the human lumbar spine.

    Science.gov (United States)

    McLain, Robert F; Yerby, Scott A; Moseley, Timothy A

    2002-04-15

    Anatomic analysis of L4 vertebral morphometry comparing specimens harvested from humans and five common large animal species. To compare fundamental structural similarities and differences in the vertebral bodies of commonly used experimental animals relative to human vertebrae. Animal models are commonly used for assessment of spine fusion, instrumentation techniques, and vertebral bone biology. Among the animals used, the lumbar vertebrae exhibit considerable anatomic variability. The goal of this study was to determine which of the animals commonly used for spine research is best suited as an anatomic model for the human lumbar spine. Morphometric features of the L4 vertebrae of five common research animals were compared with those of the human L4 vertebrae. Mature canines, immature pigs, mature micropigs, mature dairy goats, and mature sheep were analyzed. These species were chosen because they are commonly selected research animals, and most research facilities do not need to be modified to use them. The samples included ten L4 vertebrae of each animal species and seven human L4 vertebrae. Each specimen was meticulously cleaned of all soft tissue. The measurements were grouped into vertebral body parameters, neural canal dimensions, and pedicle and facet morphometery. The mean of each anatomic measurement was compared using a single factor analysis of variance and a Scheffe's post hoc test, with 0.05 denoting significance. The human vertebral body was significantly wider and deeper in the anteroposterior plane than any of the animals studied. However, the mean vertebral body height of the sheep and goat significantly exceeded that of the human specimens. The mean pedicle angle of every animal species was significantly greater than that of the human. The mean pedicle width of the micropig and goat were significantly narrower than the human pedicles, and the dog specimens lacked a definable pedicle altogether. There was no significant difference in mean pedicle

  6. Soil Moisture Active Passive (SMAP) Mission Level 4 Surface and Root Zone Soil Moisture (L4_SM) Product Specification Document

    Science.gov (United States)

    Reichle, Rolf H.; Ardizzone, Joseph V.; Kim, Gi-Kong; Lucchesi, Robert A.; Smith, Edmond B.; Weiss, Barry H.

    2015-01-01

    This is the Product Specification Document (PSD) for Level 4 Surface and Root Zone Soil Moisture (L4_SM) data for the Science Data System (SDS) of the Soil Moisture Active Passive (SMAP) project. The L4_SM data product provides estimates of land surface conditions based on the assimilation of SMAP observations into a customized version of the NASA Goddard Earth Observing System, Version 5 (GEOS-5) land data assimilation system (LDAS). This document applies to any standard L4_SM data product generated by the SMAP Project. The Soil Moisture Active Passive (SMAP) mission will enhance the accuracy and the resolution of space-based measurements of terrestrial soil moisture and freeze-thaw state. SMAP data products will have a noteworthy impact on multiple relevant and current Earth Science endeavors. These include: Understanding of the processes that link the terrestrial water, the energy and the carbon cycles, Estimations of global water and energy fluxes over the land surfaces, Quantification of the net carbon flux in boreal landscapes Forecast skill of both weather and climate, Predictions and monitoring of natural disasters including floods, landslides and droughts, and Predictions of agricultural productivity. To provide these data, the SMAP mission will deploy a satellite observatory in a near polar, sun synchronous orbit. The observatory will house an L-band radiometer that operates at 1.40 GHz and an L-band radar that operates at 1.26 GHz. The instruments will share a rotating reflector antenna with a 6 meter aperture that scans over a 1000 km swath.

  7. CARVE: L4 Gridded Particle Trajectories for WRF-STILT model, 2012-2016

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides Weather Research and Forecasting (WRF) Stochastic Time-Inverted Lagrangian Transport (STILT) model inputs for particle receptors located at...

  8. Technical Report Series on Global Modeling and Data Assimilation. Volume 42; Soil Moisture Active Passive (SMAP) Project Calibration and Validation for the L4_C Beta-Release Data Product

    Science.gov (United States)

    Koster, Randal D. (Editor); Kimball, John S.; Jones, Lucas A.; Glassy, Joseph; Stavros, E. Natasha; Madani, Nima (Editor); Reichle, Rolf H.; Jackson, Thomas; Colliander, Andreas

    2015-01-01

    During the post-launch Cal/Val Phase of SMAP there are two objectives for each science product team: 1) calibrate, verify, and improve the performance of the science algorithms, and 2) validate accuracies of the science data products as specified in the L1 science requirements according to the Cal/Val timeline. This report provides analysis and assessment of the SMAP Level 4 Carbon (L4_C) product specifically for the beta release. The beta-release version of the SMAP L4_C algorithms utilizes a terrestrial carbon flux model informed by SMAP soil moisture inputs along with optical remote sensing (e.g. MODIS) vegetation indices and other ancillary biophysical data to estimate global daily NEE and component carbon fluxes, particularly vegetation gross primary production (GPP) and ecosystem respiration (Reco). Other L4_C product elements include surface (<10 cm depth) soil organic carbon (SOC) stocks and associated environmental constraints to these processes, including soil moisture and landscape FT controls on GPP and Reco (Kimball et al. 2012). The L4_C product encapsulates SMAP carbon cycle science objectives by: 1) providing a direct link between terrestrial carbon fluxes and underlying freeze/thaw and soil moisture constraints to these processes, 2) documenting primary connections between terrestrial water, energy and carbon cycles, and 3) improving understanding of terrestrial carbon sink activity in northern ecosystems.

  9. A finite element model of the L4-L5-S1 human spine segment including the heterogeneity and anisotropy of the discs.

    Science.gov (United States)

    Jaramillo, Hector E; Gómez, Lessby; García, Jose J

    2015-01-01

    With the aim to study disc degeneration and the risk of injury during occupational activities, a new finite element (FE) model of the L4-L5-S1 segment of the human spine was developed based on the anthropometry of a typical Colombian worker. Beginning with medical images, the programs CATIA and SOLIDWORKS were used to generate and assemble the vertebrae and create the soft structures of the segment. The software ABAQUS was used to run the analyses, which included a detailed model calibration using the experimental step-wise reduction data for the L4-L5 component, while the L5-S1 segment was calibrated in the intact condition. The range of motion curves, the intradiscal pressure and the lateral bulging under pure moments were considered for the calibration. As opposed to other FE models that include the L5-S1 disc, the model developed in this study considered the regional variations and anisotropy of the annulus as well as a realistic description of the nucleus geometry, which allowed an improved representation of experimental data during the validation process. Hence, the model can be used to analyze the stress and strain distributions in the L4-L5 and L5-S1 discs of workers performing activities such as lifting and carrying tasks.

  10. Technical Report Series on Global Modeling and Data Assimilation. Volume 40; Soil Moisture Active Passive (SMAP) Project Assessment Report for the Beta-Release L4_SM Data Product

    Science.gov (United States)

    Koster, Randal D.; Reichle, Rolf H.; De Lannoy, Gabrielle J. M.; Liu, Qing; Colliander, Andreas; Conaty, Austin; Jackson, Thomas; Kimball, John

    2015-01-01

    During the post-launch SMAP calibration and validation (Cal/Val) phase there are two objectives for each science data product team: 1) calibrate, verify, and improve the performance of the science algorithm, and 2) validate the accuracy of the science data product as specified in the science requirements and according to the Cal/Val schedule. This report provides an assessment of the SMAP Level 4 Surface and Root Zone Soil Moisture Passive (L4_SM) product specifically for the product's public beta release scheduled for 30 October 2015. The primary objective of the beta release is to allow users to familiarize themselves with the data product before the validated product becomes available. The beta release also allows users to conduct their own assessment of the data and to provide feedback to the L4_SM science data product team. The assessment of the L4_SM data product includes comparisons of SMAP L4_SM soil moisture estimates with in situ soil moisture observations from core validation sites and sparse networks. The assessment further includes a global evaluation of the internal diagnostics from the ensemble-based data assimilation system that is used to generate the L4_SM product. This evaluation focuses on the statistics of the observation-minus-forecast (O-F) residuals and the analysis increments. Together, the core validation site comparisons and the statistics of the assimilation diagnostics are considered primary validation methodologies for the L4_SM product. Comparisons against in situ measurements from regional-scale sparse networks are considered a secondary validation methodology because such in situ measurements are subject to upscaling errors from the point-scale to the grid cell scale of the data product. Based on the limited set of core validation sites, the assessment presented here meets the criteria established by the Committee on Earth Observing Satellites for Stage 1 validation and supports the beta release of the data. The validation against

  11. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface......Recent advances in integrated hydrological and soil-vegetation-atmosphere transfer (SVAT) modelling have led to improved water resource management practices, greater crop production, and better flood forecasting systems. However, uncertainty is inherent in all numerical models ultimately leading...... hydrological and tested by assimilating synthetic hydraulic head observations in a catchment in Denmark. Assimilation led to a substantial reduction of model prediction error, and better model forecasts. Also, a new assimilation scheme is developed to downscale and bias-correct coarse satellite derived soil...

  12. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    Recent advances in integrated hydrological and soil-vegetation-atmosphere transfer (SVAT) modelling have led to improved water resource management practices, greater crop production, and better flood forecasting systems. However, uncertainty is inherent in all numerical models ultimately leading...... and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface...... hydrological and tested by assimilating synthetic hydraulic head observations in a catchment in Denmark. Assimilation led to a substantial reduction of model prediction error, and better model forecasts. Also, a new assimilation scheme is developed to downscale and bias-correct coarse satellite derived soil...

  13. Predictive Surface Complexation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sverjensky, Dimitri A. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Earth and Planetary Sciences

    2016-11-29

    Surface complexation plays an important role in the equilibria and kinetics of processes controlling the compositions of soilwaters and groundwaters, the fate of contaminants in groundwaters, and the subsurface storage of CO2 and nuclear waste. Over the last several decades, many dozens of individual experimental studies have addressed aspects of surface complexation that have contributed to an increased understanding of its role in natural systems. However, there has been no previous attempt to develop a model of surface complexation that can be used to link all the experimental studies in order to place them on a predictive basis. Overall, my research has successfully integrated the results of the work of many experimentalists published over several decades. For the first time in studies of the geochemistry of the mineral-water interface, a practical predictive capability for modeling has become available. The predictive correlations developed in my research now enable extrapolations of experimental studies to provide estimates of surface chemistry for systems not yet studied experimentally and for natural and anthropogenically perturbed systems.

  14. Soil Moisture Active Passive Mission L4_SM Data Product Assessment (Version 2 Validated Release)

    Science.gov (United States)

    Reichle, Rolf Helmut; De Lannoy, Gabrielle J. M.; Liu, Qing; Ardizzone, Joseph V.; Chen, Fan; Colliander, Andreas; Conaty, Austin; Crow, Wade; Jackson, Thomas; Kimball, John; hide

    2016-01-01

    core validation site comparisons indicate that "Version 2" of the L4_SM data product meets the self-imposed L4_SM accuracy requirement, which is formulated in terms of the ubRMSE: the RMSE (Root Mean Square Error) after removal of the long-term mean difference. The overall ubRMSE of the 3-hourly L4_SM surface soil moisture at the 9 km scale is 0.035 cubic meters per cubic meter requirement. The corresponding ubRMSE for L4_SM root zone soil moisture is 0.024 cubic meters per cubic meter requirement. Both of these metrics are comfortably below the 0.04 cubic meters per cubic meter requirement. The L4_SM estimates are an improvement over estimates from a model-only SMAP Nature Run version 4 (NRv4), which demonstrates the beneficial impact of the SMAP brightness temperature data. L4_SM surface soil moisture estimates are consistently more skillful than NRv4 estimates, although not by a statistically significant margin. The lack of statistical significance is not surprising given the limited data record available to date. Root zone soil moisture estimates from L4_SM and NRv4 have similar skill. Results from comparisons of the L4_SM product to in situ measurements from nearly 400 sparse network sites corroborate the core validation site results. The instantaneous soil moisture and soil temperature analysis increments are within a reasonable range and result in spatially smooth soil moisture analyses. The O-F residuals exhibit only small biases on the order of 1-3 degrees Kelvin between the (re-scaled) SMAP brightness temperature observations and the L4_SM model forecast, which indicates that the assimilation system is largely unbiased. The spatially averaged time series standard deviation of the O-F residuals is 5.9 degrees Kelvin, which reduces to 4.0 degrees Kelvin for the observation-minus-analysis (O-A) residuals, reflecting the impact of the SMAP observations on the L4_SM system. Averaged globally, the time series standard deviation of the normalized O-F residuals is

  15. Modeling conoid surfaces

    OpenAIRE

    Velimirović Ljubica S.; Stanković Mića S.; Radivojević Grozdana

    2002-01-01

    In tins paper we consider conoid surfaces as frequently used surfaces in building techniques, mainly as daring roof structures. Different types of conoids are presented using the programme package Mathematica. We describe the generation of conoids and by means of parametric representation we get their graphics. The geometric approach offers a wide range of possibilities in the research of complicated spatial surface systems.

  16. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    related to inaccurate land surface modelling, e.g. enhanced warm bias in warm dry summer months. Coupling the regional climate model to a hydrological model shows the potential of improving the surface flux simulations in dry periods and the 2 m air temperature in general. In the dry periods......The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...

  17. Rotational properties of L4 Trojan asteroids from K2

    Science.gov (United States)

    Ryan, Erin L.; Woodward, Charles E.; Sharkey, Benjamin N. L.

    2016-10-01

    Our understanding of solar system formation is undergoing a renaissance as new planetary systems are found, often unlike our own. Many questions now ask how the giant planets and their satellite systems accreted and if there is evidence that they migrated to new orbital positions. One of the keys to understanding these questions within our own solar system is the Jupiter Trojan population which is co-orbital with Jupiter. The two Trojan clouds at the stable L4 and L5 Lagrangian points are in orbits which are stable over the age of the Solar System, unlike many other present epoch small body populations. Planetary migration models suggest that the Trojan asteroids, and the dynamically hot (i.e. "scattered"), population of Kuiper Belt objects originate from the same region in the early solar system. While these objects would have started with the same compositions, establishing compositional linkages is challenging and complicated due to a paucity of distinct and easily identifiable mineralogical features in the optical, where these objects are the brightest. While the surface compositions and colors of the Trojans match objects in the inner solar system, as well as the Kuiper Belt, physical characterization of this large population of objects has been scarce. During Campaign 6 in late 2015, the 115 square degree K2 spacecraft field of view overlapped with the L4 Trojan cloud, allowing for long term monitoring. We report on the fitted rotational periods and lightcurve amplitudes from 56 Trojan asteroids that were observed for an average of 11 days by K2. We find ~20% of objects have rotational periods longer than 50 hours and ~40% of the objects have lightcurves with shapes characteristic of contact binary systems.

  18. Alternative model of random surfaces

    International Nuclear Information System (INIS)

    Ambartzumian, R.V.; Sukiasian, G.S.; Savvidy, G.K.; Savvidy, K.G.

    1992-01-01

    We analyse models of triangulated random surfaces and demand that geometrically nearby configurations of these surfaces must have close actions. The inclusion of this principle drives us to suggest a new action, which is a modified Steiner functional. General arguments, based on the Minkowski inequality, shows that the maximal distribution to the partition function comes from surfaces close to the sphere. (orig.)

  19. Soil Moisture Active Passive Mission L4_C Data Product Assessment (Version 2 Validated Release)

    Science.gov (United States)

    Kimball, John S.; Jones, Lucas A.; Glassy, Joseph; Stavros, E. Natasha; Madani, Nima; Reichle, Rolf H.; Jackson, Thomas; Colliander, Andreas

    2016-01-01

    The SMAP satellite was successfully launched January 31st 2015, and began acquiring Earth observation data following in-orbit sensor calibration. Global data products derived from the SMAP L-band microwave measurements include Level 1 calibrated and geolocated radiometric brightness temperatures, Level 23 surface soil moisture and freezethaw geophysical retrievals mapped to a fixed Earth grid, and model enhanced Level 4 data products for surface to root zone soil moisture and terrestrial carbon (CO2) fluxes. The post-launch SMAP mission CalVal Phase had two primary objectives for each science product team: 1) calibrate, verify, and improve the performance of the science algorithms, and 2) validate accuracies of the science data products as specified in the L1 science requirements. This report provides analysis and assessment of the SMAP Level 4 Carbon (L4_C) product pertaining to the validated release. The L4_C validated product release effectively replaces an earlier L4_C beta-product release (Kimball et al. 2015). The validated release described in this report incorporates a longer data record and benefits from algorithm and CalVal refinements acquired during the SMAP post-launch CalVal intensive period. The SMAP L4_C algorithms utilize a terrestrial carbon flux model informed by SMAP soil moisture inputs along with optical remote sensing (e.g. MODIS) vegetation indices and other ancillary biophysical data to estimate global daily net ecosystem CO2 exchange (NEE) and component carbon fluxes for vegetation gross primary production (GPP) and ecosystem respiration (Reco). Other L4_C product elements include surface (10 cm depth) soil organic carbon (SOC) stocks and associated environmental constraints to these processes, including soil moisture and landscape freeze/thaw (FT) controls on GPP and respiration (Kimball et al. 2012). The L4_C product encapsulates SMAP carbon cycle science objectives by: 1) providing a direct link between terrestrial carbon fluxes and

  20. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...

  1. PODAAC-ERSST-L4N40

    Data.gov (United States)

    National Aeronautics and Space Administration — The Smith & Reynolds Extended Reconstructed Sea Surface Temperature (ERSST) Level 4 dataset provides a historical reconstruction of monthly global ocean surface...

  2. GHRSST_NCDC_GLOB_L4_AVHRR_AMSR_OI_SST:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A GHRSST L4 sea surface temperature analysis produced daily at the NOAA National Climatic Data Center using optimal interpolation from AVHRR Pathfinder Version 5...

  3. GHRSST_NCDC_GLOB_L4_AVHRR_OI_SST:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A GHRSST L4 sea surface temperature analysis produced daily at the NOAA National Climatic Data Center using optimal interpolation from AVHRR Pathfinder Version 5...

  4. Soil Moisture Active Passive (SMAP) Mission Level 4 Carbon (L4_C) Product Specification Document

    Science.gov (United States)

    Glassy, Joe; Kimball, John S.; Jones, Lucas; Reichle, Rolf H.; Ardizzone, Joseph V.; Kim, Gi-Kong; Lucchesi, Robert A.; Smith, Edmond B.; Weiss, Barry H.

    2015-01-01

    This is the Product Specification Document (PSD) for Level 4 Surface and Root Zone Soil Moisture (L4_SM) data for the Science Data System (SDS) of the Soil Moisture Active Passive (SMAP) project. The L4_SM data product provides estimates of land surface conditions based on the assimilation of SMAP observations into a customized version of the NASA Goddard Earth Observing System, Version 5 (GEOS-5) land data assimilation system (LDAS). This document applies to any standard L4_SM data product generated by the SMAP Project.

  5. Surface EXAFS - A mathematical model

    International Nuclear Information System (INIS)

    Bateman, J.E.

    2002-01-01

    Extended X-ray absorption fine structure (EXAFS) studies are a powerful technique for studying the chemical environment of specific atoms in a molecular or solid matrix. The study of the surface layers of 'thick' materials introduces special problems due to the different escape depths of the various primary and secondary emission products which follow X-ray absorption. The processes are governed by the properties of the emitted fluorescent photons or electrons and of the material. Their interactions can easily destroy the linear relation between the detected signal and the absorption cross-section. Also affected are the probe depth within the surface and the background superimposed on the detected emission signal. A general mathematical model of the escape processes is developed which permits the optimisation of the detection modality (X-rays or electrons) and the experimental variables to suit the composition of any given surface under study

  6. GLDAS Noah Land Surface Model L4 monthly 1.0 x 1.0 degree V2.0 (GLDAS_NOAH10_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data...

  7. GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree Version 2.0 V020

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data...

  8. GLDAS Noah Land Surface Model L4 monthly 1.0 x 1.0 degree Version 2.0 V020

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data...

  9. GLDAS Noah Land Surface Model L4 3 hourly 1.0 x 1.0 degree Version 2.0 V020

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data...

  10. GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree V2.0 (GLDAS_NOAH025_M) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data...

  11. GLDAS Noah Land Surface Model L4 3 hourly 0.25 x 0.25 degree Version 2.0 V020

    Data.gov (United States)

    National Aeronautics and Space Administration — Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data...

  12. Modeling surface imperfections in thin films and nanostructured surfaces

    DEFF Research Database (Denmark)

    Hansen, Poul-Erik; Madsen, J. S.; Jensen, S. A.

    2017-01-01

    Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection...

  13. Lunar surface vehicle model competition

    Science.gov (United States)

    1990-01-01

    During Fall and Winter quarters, Georgia Tech's School of Mechanical Engineering students designed machines and devices related to Lunar Base construction tasks. These include joint projects with Textile Engineering students. Topics studied included lunar environment simulator via drop tower technology, lunar rated fasteners, lunar habitat shelter, design of a lunar surface trenching machine, lunar support system, lunar worksite illumination (daytime), lunar regolith bagging system, sunlight diffusing tent for lunar worksite, service apparatus for lunar launch vehicles, lunar communication/power cables and teleoperated deployment machine, lunar regolith bag collection and emplacement device, soil stabilization mat for lunar launch/landing site, lunar rated fastening systems for robotic implementation, lunar surface cable/conduit and automated deployment system, lunar regolith bagging system, and lunar rated fasteners and fastening systems. A special topics team of five Spring quarter students designed and constructed a remotely controlled crane implement for the SKITTER model.

  14. Surface-complexation models for sorption onto heterogeneous surfaces

    International Nuclear Information System (INIS)

    Harvey, K.B.

    1997-10-01

    This report provides a description of the discrete-logK spectrum model, together with a description of its derivation, and of its place in the larger context of surface-complexation modelling. The tools necessary to apply the discrete-logK spectrum model are discussed, and background information appropriate to this discussion is supplied as appendices. (author)

  15. Surface Flux Modeling for Air Quality Applications

    Directory of Open Access Journals (Sweden)

    Limei Ran

    2011-08-01

    Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

  16. Minimal Model Theory for Log Surfaces

    OpenAIRE

    Fujino, Osamu

    2012-01-01

    We discuss the log minimal model theory for log surfaces. We show that the log minimal model program, the finite generation of log canonical rings, and the log abundance theorem for log surfaces hold true under assumptions weaker than the usual framework of the log minimal model theory.

  17. Dynamical modeling of surface tension

    International Nuclear Information System (INIS)

    Brackbill, J.U.; Kothe, D.B.

    1996-01-01

    In a recent review it is said that free-surface flows ''represent some of the difficult remaining challenges in computational fluid dynamics''. There has been progress with the development of new approaches to treating interfaces, such as the level-set method and the improvement of older methods such as the VOF method. A common theme of many of the new developments has been the regularization of discontinuities at the interface. One example of this approach is the continuum surface force (CSF) formulation for surface tension, which replaces the surface stress given by Laplace's equation by an equivalent volume force. Here, we describe how CSF might be made more useful. Specifically, we consider a derivation of the CSF equations from a minimization of surface energy as outlined by Jacqmin. This reformulation suggests that if one eliminates the computation of curvature in terms of a unit normal vector, parasitic currents may be eliminated For this reformulation to work, it is necessary that transition region thickness be controlled. Various means for this, in addition to the one discussed by Jacqmin are discussed

  18. Dynamic Factor Models for the Volatility Surface

    DEFF Research Database (Denmark)

    van der Wel, Michel; Ozturk, Sait R.; Dijk, Dick van

    The implied volatility surface is the collection of volatilities implied by option contracts for different strike prices and time-to-maturity. We study factor models to capture the dynamics of this three-dimensional implied volatility surface. Three model types are considered to examine desirable...

  19. Single-layer model for surface roughness.

    Science.gov (United States)

    Carniglia, C K; Jensen, D G

    2002-06-01

    Random roughness of an optical surface reduces its specular reflectance and transmittance by the scattering of light. The reduction in reflectance can be modeled by a homogeneous layer on the surface if the refractive index of the layer is intermediate to the indices of the media on either side of the surface. Such a layer predicts an increase in the transmittance of the surface and therefore does not provide a valid model for the effects of scatter on the transmittance. Adding a small amount of absorption to the layer provides a model that predicts a reduction in both reflectance and transmittance. The absorbing layer model agrees with the predictions of a scalar scattering theory for a layer with a thickness that is twice the rms roughness of the surface. The extinction coefficient k for the layer is proportional to the thickness of the layer.

  20. Bag model with diffuse surface

    International Nuclear Information System (INIS)

    Phatak, S.C.

    1986-01-01

    The constraint of a sharp bag boundary in the bag model is relaxed in the present work. This has been achieved by replacing the square-well potential of the bag model by a smooth scalar potential and introducing a term similar to the bag pressure term. The constraint of the conservation of the energy-momentum tensor is used to obtain an expression for the added bag pressure term. The model is then used to determine the static properties of the nucleon. The calculation shows that the rms charge radius and the nucleon magnetic moment are larger than the corresponding bag model values. Also, the axial vector coupling constant and the πNN coupling constant are in better agreement with the experimental values

  1. Response Surface Modeling Using Multivariate Orthogonal Functions

    Science.gov (United States)

    Morelli, Eugene A.; DeLoach, Richard

    2001-01-01

    A nonlinear modeling technique was used to characterize response surfaces for non-dimensional longitudinal aerodynamic force and moment coefficients, based on wind tunnel data from a commercial jet transport model. Data were collected using two experimental procedures - one based on modem design of experiments (MDOE), and one using a classical one factor at a time (OFAT) approach. The nonlinear modeling technique used multivariate orthogonal functions generated from the independent variable data as modeling functions in a least squares context to characterize the response surfaces. Model terms were selected automatically using a prediction error metric. Prediction error bounds computed from the modeling data alone were found to be- a good measure of actual prediction error for prediction points within the inference space. Root-mean-square model fit error and prediction error were less than 4 percent of the mean response value in all cases. Efficacy and prediction performance of the response surface models identified from both MDOE and OFAT experiments were investigated.

  2. An Improved MUSIC Model for Gibbsite Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Scott C.; Bickmore, Barry R.; Tadanier, Christopher J.; Rosso, Kevin M.

    2004-06-01

    Here we use gibbsite as a model system with which to test a recently published, bond-valence method for predicting intrinsic pKa values for surface functional groups on oxides. At issue is whether the method is adequate when valence parameters for the functional groups are derived from ab initio structure optimization of surfaces terminated by vacuum. If not, ab initio molecular dynamics (AIMD) simulations of solvated surfaces (which are much more computationally expensive) will have to be used. To do this, we had to evaluate extant gibbsite potentiometric titration data that where some estimate of edge and basal surface area was available. Applying BET and recently developed atomic force microscopy methods, we found that most of these data sets were flawed, in that their surface area estimates were probably wrong. Similarly, there may have been problems with many of the titration procedures. However, one data set was adequate on both counts, and we applied our method of surface pKa int prediction to fitting a MUSIC model to this data with considerable success—several features of the titration data were predicted well. However, the model fit was certainly not perfect, and we experienced some difficulties optimizing highly charged, vacuum-terminated surfaces. Therefore, we conclude that we probably need to do AIMD simulations of solvated surfaces to adequately predict intrinsic pKa values for surface functional groups.

  3. Partitioning of the L4-L5 dynamic moment into disc, ligamentous, and muscular components during lifting.

    Science.gov (United States)

    McGill, S M; Norman, R W

    1986-09-01

    This work describes a dynamic model of the low back that incorporates extensive anatomical detail of a three-dimensional musculo-ligamentous-skeletal system. The reactive moment about L4-L5, determined from sagittal plane lifts, was partitioned into restorative components provided by the disc in bending, ligament strain, and active muscle contraction. Skeletal kinematics were obtained from cine analysis of markers on the rib cage and pelvis. The musculature was driven from surface EMG collected from six sites. When compared with past models, features of this model included improved anatomical modeling, improved monitoring of vertebral motion unit kinematics, improved estimation of neural activation of the musculature, and consideration of the effects of muscle length, velocity, cross-sectional area and passive elasticity in force estimation. Estimations of L4-L5 disc compression and shear were, on average, 16.2% and 42.5% lower, respectively, than those calculated from a simple 5 cm erector tissue moment arm length. There was no need to invoke intra-abdominal pressure or other contentious compression-reducing mechanisms. Muscle activity, particularly that of the sacrospinalis, dominated the generation of the restorative moment. Ligaments played a very minor role in the lifts studied. High muscle loads are consistent with the common clinical observation of muscle strain often produced by load handling.

  4. Foundations of elastoplasticity subloading surface model

    CERN Document Server

    Hashiguchi, Koichi

    2017-01-01

    This book is the standard text book of elastoplasticity in which the elastoplasticity theory is comprehensively described from the conventional theory for the monotonic loading to the unconventional theory for the cyclic loading behavior. Explanations of vector-tensor analysis and continuum mechanics are provided first as a foundation for elastoplasticity theory, covering various strain and stress measures and their rates with their objectivities. Elastoplasticity has been highly developed by the creation and formulation of the subloading surface model which is the unified fundamental law for irreversible mechanical phenomena in solids. The assumption that the interior of the yield surface is an elastic domain is excluded in order to describe the plastic strain rate due to the rate of stress inside the yield surface in this model aiming at the prediction of cyclic loading behavior, although the yield surface enclosing the elastic domain is assumed in all the elastoplastic models other than the subloading surf...

  5. Surface Adsorption in Nonpolarizable Atomic Models.

    Science.gov (United States)

    Whitmer, Jonathan K; Joshi, Abhijeet A; Carlton, Rebecca J; Abbott, Nicholas L; de Pablo, Juan J

    2014-12-09

    Many ionic solutions exhibit species-dependent properties, including surface tension and the salting-out of proteins. These effects may be loosely quantified in terms of the Hofmeister series, first identified in the context of protein solubility. Here, our interest is to develop atomistic models capable of capturing Hofmeister effects rigorously. Importantly, we aim to capture this dependence in computationally cheap "hard" ionic models, which do not exhibit dynamic polarization. To do this, we have performed an investigation detailing the effects of the water model on these properties. Though incredibly important, the role of water models in simulation of ionic solutions and biological systems is essentially unexplored. We quantify this via the ion-dependent surface attraction of the halide series (Cl, Br, I) and, in so doing, determine the relative importance of various hypothesized contributions to ionic surface free energies. Importantly, we demonstrate surface adsorption can result in hard ionic models combined with a thermodynamically accurate representation of the water molecule (TIP4Q). The effect observed in simulations of iodide is commensurate with previous calculations of the surface potential of mean force in rigid molecular dynamics and polarizable density-functional models. Our calculations are direct simulation evidence of the subtle but sensitive role of water thermodynamics in atomistic simulations.

  6. Modeling and Inversion of Scattered Surface waves

    NARCIS (Netherlands)

    Riyanti, C.D.

    2005-01-01

    In this thesis, we present a modeling method based on a domain-type integral representation for waves propagating along the surface of the Earth which have been scattered in the vicinity of the source or the receivers. Using this model as starting point, we formulate an inversion scheme to estimate

  7. Surface physics theoretical models and experimental methods

    CERN Document Server

    Mamonova, Marina V; Prudnikova, I A

    2016-01-01

    The demands of production, such as thin films in microelectronics, rely on consideration of factors influencing the interaction of dissimilar materials that make contact with their surfaces. Bond formation between surface layers of dissimilar condensed solids-termed adhesion-depends on the nature of the contacting bodies. Thus, it is necessary to determine the characteristics of adhesion interaction of different materials from both applied and fundamental perspectives of surface phenomena. Given the difficulty in obtaining reliable experimental values of the adhesion strength of coatings, the theoretical approach to determining adhesion characteristics becomes more important. Surface Physics: Theoretical Models and Experimental Methods presents straightforward and efficient approaches and methods developed by the authors that enable the calculation of surface and adhesion characteristics for a wide range of materials: metals, alloys, semiconductors, and complex compounds. The authors compare results from the ...

  8. Land-surface modelling in hydrological perspective

    DEFF Research Database (Denmark)

    Overgaard, Jesper; Rosbjerg, Dan; Butts, M.B.

    2006-01-01

    The purpose of this paper is to provide a review of the different types of energy-based land-surface models (LSMs) and discuss some of the new possibilities that will arise when energy-based LSMs are combined with distributed hydrological modelling. We choose to focus on energy-based approaches......, and the difficulties inherent in various evaluation procedures are presented. Finally, the dynamic coupling of hydrological and atmospheric models is explored, and the perspectives of such efforts are discussed....

  9. Minimal model for spoof acoustoelastic surface states

    DEFF Research Database (Denmark)

    Christensen, Johan; Liang, Z.; Willatzen, Morten

    2014-01-01

    Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena for the case of sound. Aided by a minimal model that is able to capture the complex wave interaction of elastic cavity modes and airborne...... sound radiation in perfect rigid panels, we construct designer acoustoelastic surface waves that are entirely controlled by the geometrical environment. Comparisons to results obtained by full-wave simu- lations confirm the feasibility of the model and we demonstrate illustrative examples...

  10. Global modelling of Cryptosporidium in surface water

    Science.gov (United States)

    Vermeulen, Lucie; Hofstra, Nynke

    2016-04-01

    Introduction Waterborne pathogens that cause diarrhoea, such as Cryptosporidium, pose a health risk all over the world. In many regions quantitative information on pathogens in surface water is unavailable. Our main objective is to model Cryptosporidium concentrations in surface waters worldwide. We present the GloWPa-Crypto model and use the model in a scenario analysis. A first exploration of global Cryptosporidium emissions to surface waters has been published by Hofstra et al. (2013). Further work has focused on modelling emissions of Cryptosporidium and Rotavirus to surface waters from human sources (Vermeulen et al 2015, Kiulia et al 2015). A global waterborne pathogen model can provide valuable insights by (1) providing quantitative information on pathogen levels in data-sparse regions, (2) identifying pathogen hotspots, (3) enabling future projections under global change scenarios and (4) supporting decision making. Material and Methods GloWPa-Crypto runs on a monthly time step and represents conditions for approximately the year 2010. The spatial resolution is a 0.5 x 0.5 degree latitude x longitude grid for the world. We use livestock maps (http://livestock.geo-wiki.org/) combined with literature estimates to calculate spatially explicit livestock Cryptosporidium emissions. For human Cryptosporidium emissions, we use UN population estimates, the WHO/UNICEF JMP sanitation country data and literature estimates of wastewater treatment. We combine our emissions model with a river routing model and data from the VIC hydrological model (http://vic.readthedocs.org/en/master/) to calculate concentrations in surface water. Cryptosporidium survival during transport depends on UV radiation and water temperature. We explore pathogen emissions and concentrations in 2050 with the new Shared Socio-economic Pathways (SSPs) 1 and 3. These scenarios describe plausible future trends in demographics, economic development and the degree of global integration. Results and

  11. Olkiluoto surface and near-surface hydrological modelling in 2010

    International Nuclear Information System (INIS)

    Karvonen, T.

    2011-08-01

    The modeling approaches carried out with the Olkiluoto surface hydrological model (SHYD) include palaeohydrological evolution of the Olkiluoto Island, examination of the boundary condition at the geosphere-biosphere interface zone, simulations related to infiltration experiment, prediction of the influence of ONKALO on hydraulic head in shallow and deep bedrock and optimisation of the shallow monitoring network. A so called short-term prediction system was developed for continuous updating of the estimated drawdowns caused by ONKALO. The palaeohydrological simulations were computed for a period starting from the time when the highest hills on Olkiluoto Island rose above sea level around 2 500 years ago. The input data needed in the model were produced by the UNTAMO-toolbox. The groundwater flow evolution is primarily driven by the postglacial land uplift and the uncertainty in the land uplift model is the biggest single factor that influences the accuracy of the results. The consistency of the boundary condition at the geosphere-biosphere interface zone (GBIZ) was studied during 2010. The comparison carried out during 2010 showed that pressure head profiles computed with the SHYD model and deep groundwater flow model FEFTRA are in good agreement with each other in the uppermost 100 m of the bedrock. This implies that flux profiles computed with the two approaches are close to each other and hydraulic heads computed at level z=0 m with the SHYD can be used as head boundary condition in the deep groundwater flow model FEFTRA. The surface hydrological model was used to analyse the results of the infiltration experiment. Increase in bedrock recharge inside WCA explains around 60-63 % from the amount of water pumped from OL-KR14 and 37-40 % of the water pumped from OL-KR14 flows towards pumping section via the hydrogeological zones. Pumping from OL-KR14 has only a minor effect on heads and fluxes in zones HZ19A and HZ19C compared to responses caused by leakages into

  12. Vision models for 3D surfaces

    Science.gov (United States)

    Mitra, Sunanda

    1992-11-01

    Different approaches to computational stereo to represent human stereo vision have been developed over the past two decades. The Marr-Poggio theory of human stereo vision is probably the most widely accepted model of the human stereo vision. However, recently developed motion stereo models which use a sequence of images taken by either a moving camera or a moving object provide an alternative method of achieving multi-resolution matching without the use of Laplacian of Gaussian operators. While using image sequences, the baseline between two camera positions for a image pair is changed for the subsequent image pair so as to achieve different resolution for each image pair. Having different baselines also avoids the inherent occlusion problem in stereo vision models. The advantage of using multi-resolution images acquired by camera positioned at different baselines over those acquired by LOG operators is that one does not have to encounter spurious edges often created by zero-crossings in the LOG operated images. Therefore in designing a computer vision system, a motion stereo model is more appropriate than a stereo vision model. However, in some applications where only a stereo pair of images are available, recovery of 3D surfaces of natural scenes are possible in a computationally efficient manner by using cepstrum matching and regularization techniques. Section 2 of this paper describes a motion stereo model using multi-scale cepstrum matching for the detection of disparity between image pairs in a sequence of images and subsequent recovery of 3D surfaces from depth-map obtained by a non convergent triangulation technique. Section 3 presents a 3D surface recovery technique from a stereo pair using cepstrum matching for disparity detection and cubic B-splines for surface smoothing. Section 4 contains the results of 3D surface recovery using both of the techniques mentioned above. Section 5 discusses the merit of 2D cepstrum matching and cubic B

  13. Nuclear surface vibrations in bag models

    International Nuclear Information System (INIS)

    Tomio, L.

    1984-01-01

    The main difficulties found in the hadron bag models are reviewed from the original version of the MIT bag model. Following, with the aim to answer two of the main difficulties in bag models, viz., the parity and the divergence illness, a dynamical model is presented. In the model, the confinement surface of the quarks (bag) is treated like a real physical object which interacts with the quarks and is exposed to vibrations. The model is applied to the nucleon, being observed that his spectrum, in the first excited levels, can be reproduced with resonable precision and obeying to the correct parity order. In the same way that in a similar work of Brown et al., it is observed to be instrumental the inclusion of the effect due to pions. (L.C.) [pt

  14. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.

    2008-01-01

    In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms a...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

  15. Grain Surface Models and Data for Astrochemistry

    Science.gov (United States)

    Cuppen, H. M.; Walsh, C.; Lamberts, T.; Semenov, D.; Garrod, R. T.; Penteado, E. M.; Ioppolo, S.

    2017-10-01

    The cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of {˜}25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions.

  16. AMMA Land surface Model Intercomparison Project (ALMIP)

    Science.gov (United States)

    Boone, A. A.; Derosnay, P.

    2007-05-01

    Extreme climatic variability has afflicted West Africa over the last half century, which has resulted in significant socio-economic consequences for the people of this region. There is therefore a need to improve seasonal to inter-annual prediction of the West-African monsoon (WAM), however, difficulties modeling the WAM arise from both the paucity of observations at sufficient space-time resolutions, and due to the complex interactions between the biosphere, atmosphere and hydrosphere over this region. In particular, there is evidence that the land surface influences the variability of the WAM over a wide range of spatio-temporal scales. A critical aspect of this coupling is the feedback between the regional atmospheric circulation and the strong meridional surface flux gradients of mass and energy. One of the main goals of the African Monsoon Multi-disciplinary Analysis (AMMA) Project is to obtain a better understanding of the physical processes influencing the West-African Monsoon (WAM) on daily to inter-annual timescales. An improved comprehension of the relevant land surface processes is being addressed through the construction of a multi-scale atmospheric and land surface parameter forcing database using a variety of sources; numerical weather prediction forecast data, remote sensing products and local scale observations. The goal of this database is to drive land surface, vegetation and hydrological models over a range of spatial scales (local to regional) in order to gain better insights into the attendant processes. This goal is being met under the auspices of the AMMA Land surface Model Intercomparison Project (ALMIP). In the recently completed Phase 1 of this project, an ensemble of state-of-the-art land surface schemes have been run in "off-line" mode (i.e. decoupled from an atmospheric model) at a regional scale over western Africa for four annual cycles (2002-5). In this talk, intercomparison results will be presented. In addition, results from a

  17. INTEGRATION OF HETEROGENOUS DIGITAL SURFACE MODELS

    Directory of Open Access Journals (Sweden)

    R. Boesch

    2012-08-01

    Full Text Available The application of extended digital surface models often reveals, that despite an acceptable global accuracy for a given dataset, the local accuracy of the model can vary in a wide range. For high resolution applications which cover the spatial extent of a whole country, this can be a major drawback. Within the Swiss National Forest Inventory (NFI, two digital surface models are available, one derived from LiDAR point data and the other from aerial images. Automatic photogrammetric image matching with ADS80 aerial infrared images with 25cm and 50cm resolution is used to generate a surface model (ADS-DSM with 1m resolution covering whole switzerland (approx. 41000 km2. The spatially corresponding LiDAR dataset has a global point density of 0.5 points per m2 and is mainly used in applications as interpolated grid with 2m resolution (LiDAR-DSM. Although both surface models seem to offer a comparable accuracy from a global view, local analysis shows significant differences. Both datasets have been acquired over several years. Concerning LiDAR-DSM, different flight patterns and inconsistent quality control result in a significantly varying point density. The image acquisition of the ADS-DSM is also stretched over several years and the model generation is hampered by clouds, varying illumination and shadow effects. Nevertheless many classification and feature extraction applications requiring high resolution data depend on the local accuracy of the used surface model, therefore precise knowledge of the local data quality is essential. The commercial photogrammetric software NGATE (part of SOCET SET generates the image based surface model (ADS-DSM and delivers also a map with figures of merit (FOM of the matching process for each calculated height pixel. The FOM-map contains matching codes like high slope, excessive shift or low correlation. For the generation of the LiDAR-DSM only first- and last-pulse data was available. Therefore only the point

  18. Progress and achievements of the ITER L-4 blanket project

    International Nuclear Information System (INIS)

    Daenner, W.; Toschi, R.; Cardella, A.

    1999-01-01

    The L-4 Blanket Project embraces the R and D of the ITER Shielding Blanket, and its main objective is the fabrication of prototype components. This paper summarises the main conclusions from the materials R and D and the development of technologies which were required for the prototype specifications and manufacturing. The main results of the ongoing testing activities, and of the component manufacture are outlined.The main objectives of the project have been achieved including improvements of the material properties and of joining technologies, which resulted in good component quality and high performance in qualification tests. (author)

  19. Progress and achievements of the ITER L-4 blanket project

    International Nuclear Information System (INIS)

    Daenner, W.; Toschi, R.; Cardella, A.

    2001-01-01

    The L-4 Blanket Project embraces the R and D of the ITER Shielding Blanket, and its main objective is the fabrication of prototype components. This paper summarises the main conclusions from the materials R and D and the development of technologies which were required for the prototype specifications and manufacturing. The main results of the ongoing testing activities, and of the component manufacture are outlined. The main objectives of the project have been achieved including improvements of the material properties and of joining technologies, which resulted in good component quality and high performance in qualification tests. (author)

  20. Modeling superhydrophobic surfaces comprised of random roughness

    Science.gov (United States)

    Samaha, M. A.; Tafreshi, H. Vahedi; Gad-El-Hak, M.

    2011-11-01

    We model the performance of superhydrophobic surfaces comprised of randomly distributed roughness that resembles natural surfaces, or those produced via random deposition of hydrophobic particles. Such a fabrication method is far less expensive than ordered-microstructured fabrication. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridge configurations for pipe flows. The present results are compared with other theoretical and experimental studies. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.

  1. Modeling of ESD events from polymeric surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Kent Bryant

    2014-03-01

    Transient electrostatic discharge (ESD) events are studied to assemble a predictive model of discharge from polymer surfaces. An analog circuit simulation is produced and its response is compared to various literature sources to explore its capabilities and limitations. Results suggest that polymer ESD events can be predicted to within an order of magnitude. These results compare well to empirical findings from other sources having similar reproducibility.

  2. Parameter optimization for surface flux transport models

    Science.gov (United States)

    Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.; Petrie, G. J. D.

    2017-11-01

    Accurate prediction of solar activity calls for precise calibration of solar cycle models. Consequently we aim to find optimal parameters for models which describe the physical processes on the solar surface, which in turn act as proxies for what occurs in the interior and provide source terms for coronal models. We use a genetic algorithm to optimize surface flux transport models using National Solar Observatory (NSO) magnetogram data for Solar Cycle 23. This is applied to both a 1D model that inserts new magnetic flux in the form of idealized bipolar magnetic regions, and also to a 2D model that assimilates specific shapes of real active regions. The genetic algorithm searches for parameter sets (meridional flow speed and profile, supergranular diffusivity, initial magnetic field, and radial decay time) that produce the best fit between observed and simulated butterfly diagrams, weighted by a latitude-dependent error structure which reflects uncertainty in observations. Due to the easily adaptable nature of the 2D model, the optimization process is repeated for Cycles 21, 22, and 24 in order to analyse cycle-to-cycle variation of the optimal solution. We find that the ranges and optimal solutions for the various regimes are in reasonable agreement with results from the literature, both theoretical and observational. The optimal meridional flow profiles for each regime are almost entirely within observational bounds determined by magnetic feature tracking, with the 2D model being able to accommodate the mean observed profile more successfully. Differences between models appear to be important in deciding values for the diffusive and decay terms. In like fashion, differences in the behaviours of different solar cycles lead to contrasts in parameters defining the meridional flow and initial field strength.

  3. A Homology Model Reveals Novel Structural Features and an Immunodominant Surface Loop/Opsonic Target in the Treponema pallidum BamA Ortholog TP_0326.

    Science.gov (United States)

    Luthra, Amit; Anand, Arvind; Hawley, Kelly L; LeDoyt, Morgan; La Vake, Carson J; Caimano, Melissa J; Cruz, Adriana R; Salazar, Juan C; Radolf, Justin D

    2015-06-01

    We recently demonstrated that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses characteristic BamA bipartite topology. Herein, we used immunofluorescence analysis (IFA) to show that only the β-barrel domain of TP_0326 contains surface-exposed epitopes in intact T. pallidum. Using the solved structure of Neisseria gonorrhoeae BamA, we generated a homology model of full-length TP_0326. Although the model predicts a typical BamA fold, the β-barrel harbors features not described in other BamAs. Structural modeling predicted that a dome comprised of three large extracellular loops, loop 4 (L4), L6, and L7, covers the barrel's extracellular opening. L4, the dome's major surface-accessible loop, contains mainly charged residues, while L7 is largely neutral and contains a polyserine tract in a two-tiered conformation. L6 projects into the β-barrel but lacks the VRGF/Y motif that anchors L6 within other BamAs. IFA and opsonophagocytosis assay revealed that L4 is surface exposed and an opsonic target. Consistent with B cell epitope predictions, immunoblotting and enzyme-linked immunosorbent assay (ELISA) confirmed that L4 is an immunodominant loop in T. pallidum-infected rabbits and humans with secondary syphilis. Antibody capture experiments using Escherichia coli expressing OM-localized TP_0326 as a T. pallidum surrogate further established the surface accessibility of L4. Lastly, we found that a naturally occurring substitution (Leu(593) → Gln(593)) in the L4 sequences of T. pallidum strains affects antibody binding in sera from syphilitic patients. Ours is the first study to employ a "structure-to-pathogenesis" approach to map the surface topology of a T. pallidum OMP within the context of syphilitic infection. Previously, we reported that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses the bipartite topology characteristic of a BamA ortholog. Using a homology

  4. Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using In Situ Measurements

    NARCIS (Netherlands)

    Reichle, Rolf H.; De Lannoy, Gabrielle J. M.; Liu, Qing; Ardizzone, Joseph V.; Colliander, Andreas; Conaty, Austin; Crow, Wade; Jackson, Thomas J.; Jones, Lucas A.; Kimball, John S.; Koster, Randal D.; Mahanama, Sarith P.; Smith, Edmond B.; Berg, Aaron; Bircher, Simone; Bosch, David; Caldwell, Todd G.; Cosh, Michael; Holifield Collins, Chandra D.; Jensen, Karsten H.; Livingston, Stan; Lopez-baeza, Ernesto; Martínez-fernández, José; Mcnairn, Heather; Moghaddam, Mahta; Pacheco, Anna; Pellarin, Thierry; Prueger, John; Rowlandson, Tracy; Seyfried, Mark; Starks, Patrick; Su, Bob; Thibeault, Marc; Van Der Velde, Rogier; Walker, Jeffrey; Wu, Xiaoling; Zeng, Yijian

    2017-01-01

    The Soil Moisture Active Passive (SMAP) mission Level-4 Surface and Root-Zone Soil Moisture (L4_SM) data product is generated by assimilating SMAP L-band brightness temperature observations into the NASA Catchment land surface model. The L4_SM product is available from 31 March 2015 to present

  5. Surface response model for quasielastic scattering

    International Nuclear Information System (INIS)

    Esbensen, H.

    1987-01-01

    The description of nucleon-nucleus inelastic scattering in terms of single-scattering has been very successful at intermediate energies. Nuclear structure is the most dominant feature at low excitations and forward scattering, and the Distorted Wave Impulse Approximation (DWIA) has been the most useful technique to extract structure information. The conventional DWIA has also been applied to quasielastic scattering. However, this method is very time-consuming at large scattering angles, since many different excitations of different multipolarities contribute to the inelastic cross section. It has therefore been useful to develop an approximate treatment that contains the main physics of quasielastic scattering. In the following the author will try to establish the connection between the DWIA and the much simpler Surface Response Model. The author will give a short description of the Random Phase Approximation that is used to calculate the nuclear response, and illustrate the spin-isospin dependence of the nucleon-nucleon t-matrix interaction, which is used to generate the excitations of the target nucleus. Finally, some of the applications of the surface response model to (p,p'), (p,n) and ( 3 H,t) reactions are reviewed. 19 refs., 5 figs

  6. Bioadhesion to model thermally responsive surfaces

    Science.gov (United States)

    Andrzejewski, Brett Paul

    This dissertation focuses on the characterization of two surfaces: mixed self-assembled monolayers (SAMs) of hexa(ethylene glycol) and alkyl thiolates (mixed SAM) and poly(N-isopropylacrylamide) (PNIPAAm). The synthesis of hexa(ethylene gylcol) alkyl thiol (C11EG 6OH) is presented along with the mass spectrometry and nuclear magnetic resonance results. The gold substrates were imaged prior to SAM formation with atomic force micrscopy (AFM). Average surface roughness of the gold substrate was 0.44 nm, 0.67 nm, 1.65 nm for 15, 25 and 60 nm gold thickness, respectively. The height of the mixed SAM was measured by ellipsometry and varied from 13 to 28°A depending on surface mole fraction of C11EG6OH. The surface mole fraction of C11EG6OH for the mixed SAM was determined by X-ray photoelectron spectroscopy (XPS) with optimal thermal responsive behavior in the range of 0.4 to 0.6. The mixed SAM surface was confirmed to be thermally responsive by contact angle goniometry, 35° at 28°C and ˜55° at 40°C. In addition, the mixed SAM surfaces were confirmed to be thermally responsive for various aqueous mediums by tensiometry. Factors such as oxygen, age, and surface mole fraction and how they affect the thermal responsive of the mixed SAM are discussed. Lastly, rat fibroblasts were grown on the mixed SAM and imaged by phase contrast microscopy to show inhibition of attachment at temperatures below the molecular transition. Qualitative and quantitative measurements of the fibroblast adhesion data are provided that support the hypothesis of the mixed SAM exhibits a dominantly non-fouling molecular conformation at 25°C whereas it exhibits a dominantly fouling molecular conformation at 40°C. The adhesion of six model proteins: bovine serum albumin, collagen, pyruvate kinase, cholera toxin subunit B, ribonuclease, and lysozyme to the model thermally responsive mixed SAM were examined using AFM. All six proteins possessed adhesion to the pure component alkyl thiol, in

  7. EUR-L4UHRFND-MED-ODYSSEA:1

    Data.gov (United States)

    National Aeronautics and Space Administration — The ODYSSEA Mediterranean Sea Surface Temperature is produced at Ifremer/CERSAT. It provides a daily cloud-free field of foundation sea surface temperature at 2 km...

  8. JPL-L4UHfnd-GLOB-MUR:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced as a retrospective dataset at the JPL Physical...

  9. Advanced finite element analysis of L4-L5 implanted spine segment

    Science.gov (United States)

    Pawlikowski, Marek; Domański, Janusz; Suchocki, Cyprian

    2015-09-01

    In the paper finite element (FE) analysis of implanted lumbar spine segment is presented. The segment model consists of two lumbar vertebrae L4 and L5 and the prosthesis. The model of the intervertebral disc prosthesis consists of two metallic plates and a polyurethane core. Bone tissue is modelled as a linear viscoelastic material. The prosthesis core is made of a polyurethane nanocomposite. It is modelled as a non-linear viscoelastic material. The constitutive law of the core, derived in one of the previous papers, is implemented into the FE software Abaqus®. It was done by means of the User-supplied procedure UMAT. The metallic plates are elastic. The most important parts of the paper include: description of the prosthesis geometrical and numerical modelling, mathematical derivation of stiffness tensor and Kirchhoff stress and implementation of the constitutive model of the polyurethane core into Abaqus® software. Two load cases were considered, i.e. compression and stress relaxation under constant displacement. The goal of the paper is to numerically validate the constitutive law, which was previously formulated, and to perform advanced FE analyses of the implanted L4-L5 spine segment in which non-standard constitutive law for one of the model materials, i.e. the prosthesis core, is implemented.

  10. MERGING DIGITAL SURFACE MODELS IMPLEMENTING BAYESIAN APPROACHES

    Directory of Open Access Journals (Sweden)

    H. Sadeq

    2016-06-01

    Full Text Available In this research different DSMs from different sources have been merged. The merging is based on a probabilistic model using a Bayesian Approach. The implemented data have been sourced from very high resolution satellite imagery sensors (e.g. WorldView-1 and Pleiades. It is deemed preferable to use a Bayesian Approach when the data obtained from the sensors are limited and it is difficult to obtain many measurements or it would be very costly, thus the problem of the lack of data can be solved by introducing a priori estimations of data. To infer the prior data, it is assumed that the roofs of the buildings are specified as smooth, and for that purpose local entropy has been implemented. In addition to the a priori estimations, GNSS RTK measurements have been collected in the field which are used as check points to assess the quality of the DSMs and to validate the merging result. The model has been applied in the West-End of Glasgow containing different kinds of buildings, such as flat roofed and hipped roofed buildings. Both quantitative and qualitative methods have been employed to validate the merged DSM. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the well established Maximum Likelihood model and showed similar quantitative statistical results and better qualitative results. Although the proposed model has been applied on DSMs that were derived from satellite imagery, it can be applied to any other sourced DSMs.

  11. A surface hydrology model for regional vector borne disease models

    Science.gov (United States)

    Tompkins, Adrian; Asare, Ernest; Bomblies, Arne; Amekudzi, Leonard

    2016-04-01

    Small, sun-lit temporary pools that form during the rainy season are important breeding sites for many key mosquito vectors responsible for the transmission of malaria and other diseases. The representation of this surface hydrology in mathematical disease models is challenging, due to their small-scale, dependence on the terrain and the difficulty of setting soil parameters. Here we introduce a model that represents the temporal evolution of the aggregate statistics of breeding sites in a single pond fractional coverage parameter. The model is based on a simple, geometrical assumption concerning the terrain, and accounts for the processes of surface runoff, pond overflow, infiltration and evaporation. Soil moisture, soil properties and large-scale terrain slope are accounted for using a calibration parameter that sets the equivalent catchment fraction. The model is calibrated and then evaluated using in situ pond measurements in Ghana and ultra-high (10m) resolution explicit simulations for a village in Niger. Despite the model's simplicity, it is shown to reproduce the variability and mean of the pond aggregate water coverage well for both locations and validation techniques. Example malaria simulations for Uganda will be shown using this new scheme with a generic calibration setting, evaluated using district malaria case data. Possible methods for implementing regional calibration will be briefly discussed.

  12. OSCAR_L4_OC_1deg:1

    Data.gov (United States)

    National Aeronautics and Space Administration — This product contains near-surface current estimates, derived using quasi-linear and steady flow momentum equations. The horizontal velocity is directly estimated...

  13. GHRSST_UKMO_GLOB_L4_OSTIA_SST:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A GHRSST Level 4 sea surface temperature analysis produced daily on an operational basis at the UK Met Office using optimal interpolation from AVHRR, AATSR, SEVIRI,...

  14. OSCAR_L4_OC_third-deg:1

    Data.gov (United States)

    National Aeronautics and Space Administration — This product contains near-surface current estimates, derived using quasi-linear and steady flow momentum equations. The horizontal velocity is directly estimated...

  15. RIPPLE: A new model for incompressible flows with free surfaces

    Science.gov (United States)

    Kothe, D. B.; Mjolsness, R. C.

    1991-09-01

    A new free surface flow model, RIPPLE, is summarized. RIPPLE obtains finite difference solutions for incompressible flow problems having strong surface tension forces at free surfaces of arbitrarily complex topology. The key innovation is the Continuum Surface Force (CSF) model which represents surface tension as a (strongly) localized volume force. Other features include a high-order momentum advection model, a volume-of-fluid free surface treatment, and an efficient two-step projection solution method. RIPPLE'S unique capabilities are illustrated with two example problems: low-gravity jet-induced tank flow, and the collision and coalescence of two cylindrical rods.

  16. RIPPLE - A new model for incompressible flows with free surfaces

    Science.gov (United States)

    Kothe, D. B.; Mjolsness, R. C.

    1991-09-01

    A new free surface flow model, RIPPLE, is summarized. RIPPLE obtains finite difference solutions for incompressible flow problems having strong surface tension forces at free surfaces of arbitrarily complex topology. The key innovation is the continuum surface force model which represents surface tension as a (strongly) localized volume force. Other features include a higher-order momentum advection model, a volume-of-fluid free surface treatment, and an efficient two-step projection solution method. RIPPLE's unique capabilities are illustrated with two example problems: low-gravity jet-induced tank flow, and the collision and coalescence of two cylindrical rods.

  17. NCA-LDAS Noah-3.3 Land Surface Model L4 Daily 0.125 x 0.125 degree V001 (NCALDAS_NOAH0125_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The National Climate Assessment - Land Data Assimilation System, or NCA-LDAS, is an integrated terrestrial water analysis system created for sustained assessment,...

  18. NCA-LDAS Noah-3.3 Land Surface Model L4 daily 0.125 x 0.125 degree V2.0 (NCALDAS_NOAH0125_D) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The National Climate Assessment - Land Data Assimilation System, or NCA-LDAS, is an integrated terrestrial water analysis system created for sustained assessment,...

  19. Comment on 'Modelling of surface energies of elemental crystals'

    International Nuclear Information System (INIS)

    Li Jinping; Luo Xiaoguang; Hu Ping; Dong Shanliang

    2009-01-01

    Jiang et al (2004 J. Phys.: Condens. Matter 16 521) present a model based on the traditional broken-bond model for predicting surface energies of elemental crystals. It is found that bias errors can be produced in calculating the coordination numbers of surface atoms, especially in the prediction of high-Miller-index surface energies. (comment)

  20. Surface CUrrents from a Diagnostic model (SCUD): Pacific

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SCUD data product is an estimate of upper-ocean velocities computed from a diagnostic model (Surface CUrrents from a Diagnostic model). This model makes daily...

  1. Surface and near-surface hydrological model of Olkiluoto island

    International Nuclear Information System (INIS)

    Karvonen, T.

    2008-04-01

    The aim of the study was to develop a 3D-model that calculates the overall water balance components of Olkiluoto Island in the present-day condition utilizing the existing extensive data sets available. The model links the unsaturated and saturated soil water in the overburden and groundwater in bedrock to a continuous pressure system. The parameterization of land use and vegetation was done in such a way that the model can later on be used for description of the past evolution of the overburden hydrology at the site and overburden's hydrological evolution in the future. Measured groundwater level in overburden tubes, pressure heads in shallow bedrock holes, snow depth, soil temperature, frost depth and discharge measurements were used in assessing the performance of the models in the calibration period (01.05.2001- 31.12.2005). Computed groundwater level variation can be characterized by variables ΔH MEAS and ΔH COMP , which are the difference between maximum and minimum measured and computed groundwater level value during the calibration period. Average ΔH MEAS for all tubes located in fine-textured till soil was 1.99 m and the corresponding computed value ΔH COMP was 1.83 m. Average ΔH MEAS for all tubes located in sandy till soil was 2.12 m and the corresponding computed value ΔH COMP was 1.93 m. The computed results indicate that in future studies it is necessary to divide the two most important soil types into several subclasses. In the present study the uncertainty and sensitivity analysis was carried out through a parameter uncertainty framework known as GLUE. According to the uncertainty analysis the average yearly runoff was around 175 mm a -1 and 50 % confidence limits were 155 and 195 mm a -1 . Measured average yearly runoff during the calibration period was 190 mm a -1 . Average yearly evapotranspiration estimate was 310 mm a -1 and the 50 % confidence limits were 290 and 330 mm a -1 . Average value for recharge through the bedrock system was 1

  2. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    Science.gov (United States)

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  3. Modeling sea-surface temperature and its variability

    Science.gov (United States)

    Sarachik, E. S.

    1985-01-01

    A brief review is presented of the temporal scales of sea surface temperature variability. Progress in modeling sea surface temperature, and remaining obstacles to the understanding of the variability is discussed.

  4. Surfaces foliated by planar geodesics: a model forcurved wood design

    DEFF Research Database (Denmark)

    Brander, David; Gravesen, Jens

    2017-01-01

    Surfaces foliated by planar geodesics are a natural model for surfaces made from wood strips. We outline how to construct all solutions, and produce non-trivial examples, such as a wood-strip Klein bottle......Surfaces foliated by planar geodesics are a natural model for surfaces made from wood strips. We outline how to construct all solutions, and produce non-trivial examples, such as a wood-strip Klein bottle...

  5. Modelling and simulation of surface water waves

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Westhuis, J.H.

    2002-01-01

    The evolution of waves on the surface of a layer of fluid is governed by non-linear effects from surface deformations and dispersive effects from the interaction with the interior fluid motion. Several simulation tools are described in this paper and compared with real life experiments in large

  6. Modelling of energetic molecule-surface interactions

    International Nuclear Information System (INIS)

    Kerford, M.

    2000-09-01

    This thesis contains the results of molecular dynamics simulations of molecule-surface interactions, looking particularly at fullerene molecules and carbon surfaces. Energetic impacts of fullerene molecules on graphite create defect craters. The relationship between the parameters of the impacting molecule and the parameters of the crater axe examined and found to be a function of the energy and velocity of the impacting molecule. Less energetic fullerene molecules can be scattered from a graphite surface and the partitioning of energy after a scattering event is investigated. It is found that a large fraction of the kinetic energy retained after impact is translational energy, with a small fraction of rotational energy and a number of vibrational modes. At impact energies where the surface is not broken and at normal incidence, surface waves axe seen to occur. These waves axe used to develop a method of desorbing molecules from a graphite surface without damage to either the surface or the molecules being desorbed. A number of fullerene molecules are investigated and ways to increase the desorption yield are examined. It is found that this is a successful technique for desorbing large numbers of intact molecules from graphite. This technique could be used for desorbing intact molecules into a gas phase for mass spectrometric analysis. (author)

  7. Model castings with composite surface layer - application

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2008-10-01

    Full Text Available The paper presents a method of usable properties of surface layers improvement of cast carbon steel 200–450, by put directly in foundingprocess a composite surface layer on the basis of Fe-Cr-C alloy. Technology of composite surface layer guarantee mainly increase inhardness and aberasive wear resistance of cast steel castings on machine elements. This technology can be competition for generallyapplied welding technology (surfacing by welding and thermal spraying. In range of studies was made cast steel test castings withcomposite surface layer, which usability for industrial applications was estimated by criterion of hardness and aberasive wear resistance of type metal-mineral and quality of joint cast steel – (Fe-Cr-C. Based on conducted studies a thesis, that composite surface layer arise from liquid state, was formulated. Moreover, possible is control of composite layer thickness and its hardness by suitable selection of parameters i.e. thickness of insert, pouring temperature and solidification modulus of casting. Possibility of technology application of composite surface layer in manufacture of cast steel slide bush for combined cutter loader is presented.

  8. Spinopelvic balance evaluation of patients with degenerative spondylolisthesis L4L5 and L4L5 herniated disc who underwent surgery ?

    OpenAIRE

    Nunes, Viviane Regina Hernandez; Jacob, Charbel; Cardoso, Igor Machado; Batista, Jos? Lucas; Brazolino, Marcus Alexandre Novo; Maia, Thiago Cardoso

    2016-01-01

    ABSTRACT OBJECTIVE: To correlate spinopelvic balance with the development of degenerative spondylolisthesis and disk herniation. METHODS: This was a descriptive retrospective study that evaluated 60 patients in this hospital, 30 patients with degenerative spondylolisthesis at the L4-L5 level and 30 with herniated disk at the L4-L5 level, all of whom underwent Surgical treatment. RESULTS: Patients with lumbar disk herniation at L4-L5 level had a mean tilt of 8.06, mean slope of 36.93, an...

  9. A surface diffuse scattering model for the mobility of electrons in surface charge coupled devices

    International Nuclear Information System (INIS)

    Ionescu, M.

    1977-01-01

    An analytical model for the mobility of electrons in surface charge coupled devices is studied on the basis of the results previously obtained, considering a surface diffuse scattering; the importance of the results obtained for a better understanding of the influence of the fringing field in surface charge coupled devices is discussed. (author)

  10. Simple model of surface roughness for binary collision sputtering simulations

    International Nuclear Information System (INIS)

    Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

    2017-01-01

    Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.

  11. Spinopelvic balance evaluation of patients with degenerative spondylolisthesis L4L5 and L4L5 herniated disc who underwent surgery.

    Science.gov (United States)

    Nunes, Viviane Regina Hernandez; Jacob, Charbel; Cardoso, Igor Machado; Batista, José Lucas; Brazolino, Marcus Alexandre Novo; Maia, Thiago Cardoso

    2016-01-01

    To correlate spinopelvic balance with the development of degenerative spondylolisthesis and disk herniation. This was a descriptive retrospective study that evaluated 60 patients in this hospital, 30 patients with degenerative spondylolisthesis at the L4-L5 level and 30 with herniated disk at the L4-L5 level, all of whom underwent Surgical treatment. Patients with lumbar disk herniation at L4-L5 level had a mean tilt of 8.06, mean slope of 36.93, and mean PI of 45. In patients with degenerative spondylolisthesis at the L4-L5 level, a mean tilt of 22.1, mean slope of 38.3, and mean PI of 61.4 were observed. This article reinforces the finding that the high mean tilt and PI are related to the onset of degenerative spondylolisthesis, and also concluded that the same angles, when low, increase the risk for disk herniation.

  12. Multi-Satellite Air Quality Sulfur Dioxide (SO2) Database Long-Term L4 Global V1 (MSAQSO2L4) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — These data are a part of Multi-Decadal Sulfur Dioxide Climatology from Satellite Instrument (MEaSUREs-12-0022 project). The catalogue MSAQSO2L4 file contains the...

  13. Spinopelvic balance evaluation of patients with degenerative spondylolisthesis L4L5 and L4L5 herniated disc who underwent surgery

    Directory of Open Access Journals (Sweden)

    Viviane Regina Hernandez Nunes

    Full Text Available ABSTRACT OBJECTIVE: To correlate spinopelvic balance with the development of degenerative spondylolisthesis and disk herniation. METHODS: This was a descriptive retrospective study that evaluated 60 patients in this hospital, 30 patients with degenerative spondylolisthesis at the L4-L5 level and 30 with herniated disk at the L4-L5 level, all of whom underwent Surgical treatment. RESULTS: Patients with lumbar disk herniation at L4-L5 level had a mean tilt of 8.06, mean slope of 36.93, and mean PI of 45. In patients with degenerative spondylolisthesis at the L4-L5 level, a mean tilt of 22.1, mean slope of 38.3, and mean PI of 61.4 were observed. CONCLUSION: This article reinforces the finding that the high mean tilt and PI are related to the onset of degenerative spondylolisthesis, and also concluded that the same angles, when low, increase the risk for disk herniation.

  14. Control of E.L.4. dismantling products

    International Nuclear Information System (INIS)

    Rotelle, O.; Dionisio Gomes, A.; Pinaux, M.

    1998-01-01

    Te Brennilis power plant ( a 70 MW heavy water moderated reactor, cooled with Co2) was shut down in July 1985, after 18 years of service. The fuel elements and the heavy water were transferred to facilities for treatment and temporary storage. The second phase of the Brennilis power plant de-construction began in September 1997. Except for the reactor building, the concrete structures will be drained and demolished after inspection and declassification. In the reactor building, only the heavy water circuits will be disassembled. Once this operation has been carried out, new work will be started to provide reactor containment and monitoring. Two types of wastes are produced by the de-construction operations (concrete, steel, nonferrous metals, electrical wiring, insulation, filters, technological wastes): low activity:medium activity wastes, i;e; stored on the surface after being treated and packaged; for very low activity wastes, two possibilities are under consideration: creation of a dedicated surface storage facility and recycling through approved channels. (N.C.)

  15. The structure of carbon nanotubes formed of graphene layers L4-8, L5-7, L3-12, L4-6-12

    Science.gov (United States)

    Shapovalova, K. E.; Belenkov, E. A.

    2017-11-01

    We geometrically calculate the optimized structure of nanotubes based on the graphene layers, using the method of molecular mechanics MM+. It was found that only the nanotubes, based on the graphene layers L4-8, L5-7, L3-12, L4-6-12, have a cylindrical form. Calculations of the sublimation energy, carried out using the semi-empirical quantum-mechanic method PM3, show that energy increases with the increase of nanotube diameters.

  16. Mathematical modeling of rainwater runoff over catchment surface ...

    African Journals Online (AJOL)

    Mathematical modeling of rainwater runoff over catchment surface and mass transfer of contaminant incoming to water stream from soil. ... rainwater runoff along the surface catchment taking account the transport of pollution which permeates into the water flow from a porous media of soil at the certain areas of this surface.

  17. Modeling laser-induced periodic surface structures: an electromagnetic approach

    NARCIS (Netherlands)

    Skolski, J.Z.P.

    2014-01-01

    This thesis presents and discusses laser-induced periodic surface structures (LIPSSs), as well as a model explaining their formation. LIPSSs are regular wavy surface structures with dimensions usually in the submicrometer range, which can develop on the surface of many materials exposed to laser

  18. Methanol Oxidation on Model Elemental and Bimetallic Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Tritsaris, G. A.; Rossmeisl, J.

    2012-01-01

    Direct methanol fuel cells are a key enabling technology for clean energy conversion. Using density functional theory calculations, we study the methanol oxidation reaction on model electrodes. We discuss trends in reactivity for a set of monometallic and bimetallic transition metal surfaces, flat...... sites on the surface and to screen for novel bimetallic surfaces of enhanced activity. We suggest platinum copper surfaces as promising anode catalysts for direct methanol fuel cells....

  19. Sediment Transport Model for a Surface Irrigation System

    OpenAIRE

    Mailapalli, Damodhara R.; Raghuwanshi, Narendra S.; Singh, Rajendra

    2013-01-01

    Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in fur...

  20. Towards a Revised Monte Carlo Neutral Particle Surface Interaction Model

    International Nuclear Information System (INIS)

    Stotler, D.P.

    2005-01-01

    The components of the neutral- and plasma-surface interaction model used in the Monte Carlo neutral transport code DEGAS 2 are reviewed. The idealized surfaces and processes handled by that model are inadequate for accurately simulating neutral transport behavior in present day and future fusion devices. We identify some of the physical processes missing from the model, such as mixed materials and implanted hydrogen, and make some suggestions for improving the model

  1. A model of the ideal molecular surface

    Science.gov (United States)

    Henson, Bryan; Smilowitz, Laura

    2014-03-01

    We utilize two manifestations of the phenomena of the quasiliquid phase on the surface of molecular crystals to formulate a universal thermodynamic theory describing the thickness of the layer as a function of the liquid phase activity. We use direct measurements of the liquid thickness as a function of temperature and measurements of the acceleration of thermal decomposition as a function of temperature approaching the melting point to illustrate the mechanism. We show that given the existence of a liquid phase below the melting point the ideal liquid activity is necessarily a fixed function of the free energies of sublimation and vaporization. We use this activity to create a reduced formula for the liquid thickness generally applicable to the molecular surface. We provide a prediction of the mechanism and kinetics of quasiliquid formation and show that the phase exists as a metastable kinetic steady state. We show that to first order the principle controlling feature of the system is the configurational entropy of the liquid/solid interface, rather than the specifics of the surface potential energy. This is analogous to other bulk colligative phenomena such as ideal gas and solution theories, and is thus an ideal, universal formulation of inherent, thermodynamically driven, surface disorder.

  2. Surface aerodynamic temperature modeling over rainfed cotton

    Science.gov (United States)

    Evapotranspiration (ET) or latent heat flux (LE) can be spatially estimated as an energy balance (EB) residual for land surfaces using remote sensing inputs. The EB equation requires the estimation of net radiation (Rn), soil heat flux (G), and sensible heat flux (H). Rn and G can be estimated with ...

  3. Model for the Evolving Bed Surface around an Offshore Monopile

    DEFF Research Database (Denmark)

    Hartvig, Peres Akrawi

    2012-01-01

    This paper presents a model for the bed surface around an offshore monopile. The model has been designed from measured laboratory bed surfaces and is shown to reproduce these satisfactorily for both scouring and backfilling. The local rate of the bed elevation is assumed to satisfy a certain gene...

  4. Modeling the Soul Surface Seal from a Filtration Perspective

    OpenAIRE

    N.M. Somaratne; K.R.J. Smettem

    1998-01-01

    A physically based model of soil surface scaling is proposed. The governing equations are formulated on the principle of conservation of mass assuming Darcy's law applies to suspension flowing through the soil surface. The model incorporates the physics of surface sealing by mechanisms that capture suspended particles moving with infiltrating water. As a result of particle retention in the soil system, the intrinsic porosity is reduced and hulk density is increased, resulting in changes to so...

  5. L4-L5 compression and anterior/posterior joint shear forces in cabin attendants during the initial push/pull actions of airplane meal carts.

    Science.gov (United States)

    Sandfeld, Jesper; Rosgaard, Christian; Jensen, Bente Rona

    2014-07-01

    The aim of the present study was to assess the acute low back load of cabin attendants during cart handling and to identify working situations which present the highest strain on the worker. In a setup, 17 cabin attendants (ten females and seven males) pushed, pulled and turned a 20 kg standard meal cart (L: 0.5m × W: 0.3 m × H: 0.92 m) loaded with extra 20 kg and 40 kg, respectively on two different surfaces (carpet and linoleum) and at three floor inclinations (-2°, 0° and +2°). Two force transducers were mounted as handles. Two-dimensional movement analysis was performed and a 4D WATBAK modelling tool was used to calculate the acute L4-L5 load. No working situations created loads greater than the accepted values for single exertions, however compression and anterior/posterior shear forces during pulling and turning were much higher when compared with pushing. There were significant effects of handling the cart on different floor types, at the varying inclinations and with different cart weights. Additionally, when external forces were reduced, the cabin attendants did not decrease push/pull force proportionally and thus the L4-L5 load did not decrease as much as expected. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  6. Estimates of surface methane emissions over Europe using observed surface concentrations and the FLEXPART trajectory model

    Science.gov (United States)

    Weaver, C. J.; Kiemle, C.; Kawa, S. R.; Aalto, T.; Necki, J.; Steinbacher, M.; Arduini, J.; Apadula, F.; Berkhout, H.; Hatakka, J.; O'Doherty, S.

    2013-12-01

    We use surface methane observations from nine European ground stations, and the FLEXPART Lagrangian transport model to obtain surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands and the coal mines in Upper Silesia Poland. This is qualitatively consistent with the EDGAR surface flux inventory. We also report significant surface fluxes from wetlands in southern Finland during July and August and reduced wetland fluxes later in the year. Our simulated methane surface concentration captures at least half of the daily variability in the observations, suggesting that the transport model is correctly simulating the regional transport pathways over Europe. We also use our trajectory model to determine whether future space-based remote sensing instruments (MERLIN) will be able to detect both natural and anthropogenic changes in the surface flux strengths.

  7. Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model

    Science.gov (United States)

    Patricia L. Andrews

    2012-01-01

    Rothermel's surface fire spread model was developed to use a value for the wind speed that affects surface fire, called midflame wind speed. Models have been developed to adjust 20-ft wind speed to midflame wind speed for sheltered and unsheltered surface fuel. In this report, Wind Adjustment Factor (WAF) model equations are given, and the BehavePlus fire modeling...

  8. Olkiluoto surface hydrological modelling: Update 2012 including salt transport modelling

    International Nuclear Information System (INIS)

    Karvonen, T.

    2013-11-01

    Posiva Oy is responsible for implementing a final disposal program for spent nuclear fuel of its owners Teollisuuden Voima Oyj and Fortum Power and Heat Oy. The spent nuclear fuel is planned to be disposed at a depth of about 400-450 meters in the crystalline bedrock at the Olkiluoto site. Leakages located at or close to spent fuel repository may give rise to the upconing of deep highly saline groundwater and this is a concern with regard to the performance of the tunnel backfill material after the closure of the tunnels. Therefore a salt transport sub-model was added to the Olkiluoto surface hydrological model (SHYD). The other improvements include update of the particle tracking algorithm and possibility to estimate the influence of open drillholes in a case where overpressure in inflatable packers decreases causing a hydraulic short-circuit between hydrogeological zones HZ19 and HZ20 along the drillhole. Four new hydrogeological zones HZ056, HZ146, BFZ100 and HZ039 were added to the model. In addition, zones HZ20A and HZ20B intersect with each other in the new structure model, which influences salinity upconing caused by leakages in shafts. The aim of the modelling of long-term influence of ONKALO, shafts and repository tunnels provide computational results that can be used to suggest limits for allowed leakages. The model input data included all the existing leakages into ONKALO (35-38 l/min) and shafts in the present day conditions. The influence of shafts was computed using eight different values for total shaft leakage: 5, 11, 20, 30, 40, 50, 60 and 70 l/min. The selection of the leakage criteria for shafts was influenced by the fact that upconing of saline water increases TDS-values close to the repository areas although HZ20B does not intersect any deposition tunnels. The total limit for all leakages was suggested to be 120 l/min. The limit for HZ20 zones was proposed to be 40 l/min: about 5 l/min the present day leakages to access tunnel, 25 l/min from

  9. Predictive model for ice formation on superhydrophobic surfaces.

    Science.gov (United States)

    Bahadur, Vaibhav; Mishchenko, Lidiya; Hatton, Benjamin; Taylor, J Ashley; Aizenberg, Joanna; Krupenkin, Tom

    2011-12-06

    The prevention and control of ice accumulation has important applications in aviation, building construction, and energy conversion devices. One area of active research concerns the use of superhydrophobic surfaces for preventing ice formation. The present work develops a physics-based modeling framework to predict ice formation on cooled superhydrophobic surfaces resulting from the impact of supercooled water droplets. This modeling approach analyzes the multiple phenomena influencing ice formation on superhydrophobic surfaces through the development of submodels describing droplet impact dynamics, heat transfer, and heterogeneous ice nucleation. These models are then integrated together to achieve a comprehensive understanding of ice formation upon impact of liquid droplets at freezing conditions. The accuracy of this model is validated by its successful prediction of the experimental findings that demonstrate that superhydrophobic surfaces can fully prevent the freezing of impacting water droplets down to surface temperatures of as low as -20 to -25 °C. The model can be used to study the influence of surface morphology, surface chemistry, and fluid and thermal properties on dynamic ice formation and identify parameters critical to achieving icephobic surfaces. The framework of the present work is the first detailed modeling tool developed for the design and analysis of surfaces for various ice prevention/reduction strategies. © 2011 American Chemical Society

  10. Surface potential modeling and reconstruction in Kelvin probe force microscopy.

    Science.gov (United States)

    Xu, Jie; Wu, Yangqing; Li, Wei; Xu, Jun

    2017-09-08

    Kelvin probe force microscopy (KPFM) measurement has been extensively applied in metallic, semiconductor and organic electronic or photovoltaic devices, to characterize the local contact potential difference or surface potential of the samples at the nanoscale. Here, a comprehensive modeling of surface potential in KPFM is established, from the well-known single capacitance model to a precise electrodynamic model, considering the long range property of the electrostatic force in KPFM. The limitations and relations of different models are also discussed. Besides, the feedback condition of the KPFM system is reconsidered and modified, showing that the influence of the cantilever has been overestimated by about 20% in previous reports. Afterwards, the surface potential of charged Si-nanocrystals is reconstructed based on the electrodynamic model, and the calculated surface charge density is very consistent with the macroscopic capacitance-voltage (C-V) measurement. A deep understanding and correct reconstruction of surface potential is crucial to the quantitative analysis of KPFM results.

  11. Electron and VLF travel time differences for wave-particle interactions at L=4: Pt. 2

    International Nuclear Information System (INIS)

    Rash, J.P.S.; Scourfield, M.W.J.; Dougherty, M.K.

    1984-01-01

    The cyclotron resonance or gyroresonance interaction has been widely invoked as a generation mechanism for discrete VLF emissions and plasmaspheric hiss. This interaction involves electrons and VLF waves travelling in opposite directions along a geomagnetic field line. We examine, for an interaction region in the equatorial plane at L=4, the energy of the resonant electrons as a function of VLF wave frequency and ambient equatorial electron density. Then for two different spatial configurations of the interaction and two standard plasma distribution models we examine the difference in travel times to a ground-based observer in the Southern hemisphere for the electrons and waves taking part in the interaction. This difference in travel times is shown as a function of VLF wave frequency and equatorial electron density. The results, and their significance for observations of auroral electrons and VLF at Sanae, Antarctica, are discussed and compared with similar results for the Cerenkov interaction discussed in an earlier paper

  12. Modeling noncontact atomic force microscopy resolution on corrugated surfaces

    Directory of Open Access Journals (Sweden)

    Kristen M. Burson

    2012-03-01

    Full Text Available Key developments in NC-AFM have generally involved atomically flat crystalline surfaces. However, many surfaces of technological interest are not atomically flat. We discuss the experimental difficulties in obtaining high-resolution images of rough surfaces, with amorphous SiO2 as a specific case. We develop a quasi-1-D minimal model for noncontact atomic force microscopy, based on van der Waals interactions between a spherical tip and the surface, explicitly accounting for the corrugated substrate (modeled as a sinusoid. The model results show an attenuation of the topographic contours by ~30% for tip distances within 5 Å of the surface. Results also indicate a deviation from the Hamaker force law for a sphere interacting with a flat surface.

  13. Conformally parametrized surfaces associated with CPN-1 sigma models

    International Nuclear Information System (INIS)

    Grundland, A M; Hereman, W A; Yurdusen, I-dot

    2008-01-01

    Two-dimensional parametrized surfaces immersed in the su(N) algebra are investigated. The focus is on surfaces parametrized by solutions of the equations for the CP N-1 sigma model. The Lie-point symmetries of the CP N-1 model are computed for arbitrary N. The Weierstrass formula for immersion is determined and an explicit formula for a moving frame on a surface is constructed. This allows us to determine the structural equations and geometrical properties of surfaces in R N 2 -1 . The fundamental forms, Gaussian and mean curvatures, Willmore functional and topological charge of surfaces are given explicitly in terms of any holomorphic solution of the CP 2 model. The approach is illustrated through several examples, including surfaces immersed in low-dimensional su(N) algebras

  14. Theoretical model of fast electron emission from surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Reinhold, C.; Burgdoerfer, J. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Laboratory, TN (United States)

    1993-05-01

    Electron emission in glancing-angle ion-surface collisions has become a focus of ion-surface interactions. Electron spectra can provide detailed information on the above surface neutralization dynamics of multiply charged ions, the electronic structure of the surface (surface density of states), and the long-ranged image interactions near the surface. Recent experiments have found that the convoy peak, well known from ion-atom and ion-solid collisions, is dramatically altered. The peak is broadened and shifted in energy which has been attributed to dynamical image interactions. We present a microscopic model for the emission of fast electrons in glancing-angle surface collisions. A classical trajectory Monte Carlo approach is utilized to calculate the evolution of electrons in the presence of their self image, the projectile Coulomb field and the image potential induced by the projectile. The excitation of collective surface modes is also incorporated.

  15. Explanatory models for ecological response surfaces

    International Nuclear Information System (INIS)

    Jager, H.I.; Overton, W.S.

    1991-01-01

    Understanding the spatial organization of ecological systems is a fundamental part of ecosystem study. While discovering the causal relationships of this organization is an important goal, our purpose of spatial description on a regional scale is best met by use of explanatory variables that are somewhat removed from the mechanistic causal level. Regional level understanding is best obtained from explanatory variables that reflect spatial gradients at the regional scale and from categorical variables that describe the discrete constituents of (statistical) populations, such as lakes. In this paper, we use a regression model to predict lake acid neutralizing capacity (ANC) based on environmental predictor variables over a large region. These predictions are used to produce model-based population estimates. Two key features of our modeling approach are that is honors the spatial context and the design of the sample data. The spatial context of the data are brought into the analysis of model residuals through the interpretation of residual maps and semivariograms. The sampling design is taken into account by including stratification variables from the design in the model. This ensures that the model applies to a real population of lakes (the target population), rather than whatever hypothetical population the sample is a random sample of

  16. Digital terrain modeling and industrial surface metrology: Converging realms

    Science.gov (United States)

    Pike, R.J.

    2001-01-01

    Digital terrain modeling has a micro-and nanoscale counterpart in surface metrology, the numerical characterization of industrial surfaces. Instrumentation in semiconductor manufacturing and other high-technology fields can now contour surface irregularities down to the atomic scale. Surface metrology has been revolutionized by its ability to manipulate square-grid height matrices that are analogous to the digital elevation models (DEMs) used in physical geography. Because the shaping of industrial surfaces is a spatial process, the same concepts of analytical cartography that represent ground-surface form in geography evolved independently in metrology: The surface topography of manufactured components, exemplified here by automobile-engine cylinders, is routinely modeled by variogram analysis, relief shading, and most other techniques of parameterization and visualization familiar to geography. This article introduces industrial surface-metrology, examines the field in the context of terrain modeling and geomorphology and notes their similarities and differences, and raises theoretical issues to be addressed in progressing toward a unified practice of surface morphometry.

  17. Land Surface Microwave Emissivity Dynamics: Observations, Analysis and Modeling

    Science.gov (United States)

    Tian, Yudong; Peters-Lidard, Christa D.; Harrison, Kenneth W.; Kumar, Sujay; Ringerud, Sarah

    2014-01-01

    Land surface microwave emissivity affects remote sensing of both the atmosphere and the land surface. The dynamical behavior of microwave emissivity over a very diverse sample of land surface types is studied. With seven years of satellite measurements from AMSR-E, we identified various dynamical regimes of the land surface emission. In addition, we used two radiative transfer models (RTMs), the Community Radiative Transfer Model (CRTM) and the Community Microwave Emission Modeling Platform (CMEM), to simulate land surface emissivity dynamics. With both CRTM and CMEM coupled to NASA's Land Information System, global-scale land surface microwave emissivities were simulated for five years, and evaluated against AMSR-E observations. It is found that both models have successes and failures over various types of land surfaces. Among them, the desert shows the most consistent underestimates (by approx. 70-80%), due to limitations of the physical models used, and requires a revision in both systems. Other snow-free surface types exhibit various degrees of success and it is expected that parameter tuning can improve their performances.

  18. Simple model of surface roughness for binary collision sputtering simulations

    Science.gov (United States)

    Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

    2017-02-01

    It has been shown that surface roughness can strongly influence the sputtering yield - especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the "density gradient model") which imitates surface roughness effects. In the model, the target's atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient - leading to increased sputtering yields, similar in effect to surface roughness.

  19. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES

    Science.gov (United States)

    Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine...

  20. Measuring and modeling surface sorption dynamics of organophosphate flame retardants on impervious surfaces

    Data.gov (United States)

    U.S. Environmental Protection Agency — The data presented in this data file is a product of a journal publication. The dataset contains measured and model predicted OPFRs gas-phase and surface-phase...

  1. A Two-Surface Viscoplastic Model for the Structural Steel

    Directory of Open Access Journals (Sweden)

    Dong-Keon Kim

    Full Text Available Abstract As extension of the previous two-surface model in plasticity, a two-surface model for viscoplasticity is presented herein. In order to validate and investigate the performance of the proposed model, several numerical simulations are undertaken especially for structural steel under monotonic and cyclic loading cases, where experimental results and numerical results from the rate dependent kinematic hardening model are also provided for the reference. For all the cases studied, the proposed model can appropriately account for the rate-effects in both maximum stress and hysteretic shapes.

  2. Improved simulation of groundwater - surface water interaction in catchment models

    Science.gov (United States)

    teklesadik, aklilu; van Griensven, Ann; Anibas, Christian; Huysmans, Marijke

    2016-04-01

    Groundwater storage can have a significant contribution to stream flow, therefore a thorough understanding of the groundwater surface water interaction is of prime important when doing catchment modeling. The aim of this study is to improve the simulation of groundwater - surface water interaction in a catchment model of the upper Zenne River basin located in Belgium. To achieve this objective we used the "Groundwater-Surface water Flow" (GSFLOW) modeling software, which is an integration of the surface water modeling tool "Precipitation and Runoff Modeling system" (PRMS) and the groundwater modeling tool MODFLOW. For this case study, the PRMS model and MODFLOW model were built and calibrated independently. The PRMS upper Zenne River basin model is divided into 84 hydrological response units (HRUs) and is calibrated with flow data at the Tubize gauging station. The spatial discretization of the MODFLOW upper Zenne groundwater flow model consists of 100m grids. Natural groundwater divides and the Brussels-Charleroi canal are used as boundary conditions for the MODFLOW model. The model is calibrated using piezometric data. The GSFLOW results were evaluated against a SWAT model application and field observations of groundwater-surface water interactions along a cross section of the Zenne River and riparian zone. The field observations confirm that there is no exchange of groundwater beyond the Brussel-Charleroi canal and that the interaction at the river bed is relatively low. The results show that there is a significant difference in the groundwater simulations when using GSFLOW versus SWAT. This indicates that the groundwater component representation in the SWAT model could be improved and that a more realistic implementation of the interactions between groundwater and surface water is advisable. This could be achieved by integrating SWAT and MODFLOW.

  3. Modeling marine surface microplastic transport to assess optimal removal locations

    OpenAIRE

    Sherman, P; Van Sebille, E

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the ...

  4. Modeling the Acid-Base Properties of Montmorillonite Edge Surfaces.

    Science.gov (United States)

    Tournassat, Christophe; Davis, James A; Chiaberge, Christophe; Grangeon, Sylvain; Bourg, Ian C

    2016-12-20

    The surface reactivity of clay minerals remains challenging to characterize because of a duality of adsorption surfaces and mechanisms that does not exist in the case of simple oxide surfaces: edge surfaces of clay minerals have a variable proton surface charge arising from hydroxyl functional groups, whereas basal surfaces have a permanent negative charge arising from isomorphic substitutions. Hence, the relationship between surface charge and surface potential on edge surfaces cannot be described using the Gouy-Chapman relation, because of a spillover of negative electrostatic potential from the basal surface onto the edge surface. While surface complexation models can be modified to account for these features, a predictive fit of experimental data was not possible until recently, because of uncertainty regarding the densities and intrinsic pK a values of edge functional groups. Here, we reexamine this problem in light of new knowledge on intrinsic pK a values obtained over the past decade using ab initio molecular dynamics simulations, and we propose a new formalism to describe edge functional groups. Our simulation results yield reasonable predictions of the best available experimental acid-base titration data.

  5. Modeling and Simulating Airport Surface Operations with Gate Conflicts

    Science.gov (United States)

    Zelinski, Shannon; Windhorst, Robert

    2017-01-01

    The Surface Operations Simulator and Scheduler (SOSS) is a fast-time simulation platform used to develop and test future surface scheduling concepts such as NASAs Air Traffic Demonstration 2 of time-based surface metering at Charlotte Douglas International Airport (CLT). Challenges associated with CLT surface operations have driven much of SOSS development. Recently, SOSS functionality for modeling hardstand operations was developed to address gate conflicts, which occur when an arrival and departure wish to occupy the same gate at the same time. Because surface metering concepts such as ATD2 have the potential to increase gates conflicts as departure are held at their gates, it is important to study the interaction between surface metering and gate conflict management. Several approaches to managing gate conflicts with and without the use of hardstands were simulated and their effects on surface operations and scheduler performance compared.

  6. Hadamard model on the super Riemann surface

    Science.gov (United States)

    Shuji, Matsumoto; Shozo, Uehara; Yukinori, Yasui

    1988-12-01

    A supersymmetrically extended version of the Hadamard model is investigated. Classical solutions are given, which imply that the system is chaotic. Quantization is performed in the path integral method. The quantized energy sum rule is shown to be a superanalog of the Selberg trace formula. The Selberg super zeta function is introduced and energy spectra associated with bosonic (fermionic) states are given by order 1 zero-points (poles) of the zeta function.

  7. A Surface Water Model for the Orinoco river basin

    NARCIS (Netherlands)

    Schot, P.P.; Poot, A.; Vonk, G.; Peeters, W.H.M.

    2001-01-01

    This report describes the surface water model developed for the Orinoco river basin. In the next chapter hydrology and climate of the study area are presented. In the third chapter the general model concept is described. The fourth chapter describes the effects of various processes in the model

  8. Integrating Surface Modeling into the Engineering Design Graphics Curriculum

    Science.gov (United States)

    Hartman, Nathan W.

    2006-01-01

    It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

  9. Modeling of a nanoscale flexoelectric energy harvester with surface effects

    Science.gov (United States)

    Yan, Zhi

    2017-04-01

    This work presents the modeling of a beam energy harvester scavenging energy from ambient vibration based on the phenomenon of flexoelectricity. By considering surface elasticity, residual surface stress, surface piezoelectricity and bulk flexoelectricity, a modified Euler-Bernoulli beam model for the energy harvester is developed. After deriving the requisite energy expressions, the extended Hamilton's principle and the assumed-modes method are employed to obtain the discrete electromechanical Euler-Lagrange's equations. Then, the expressions of the steady-state electromechanical responses are given for harmonic base excitation. Numerical simulations are conducted to show the output voltage and the output power of the flexoelectric energy harvesters with different materials and sizes. Particular emphasis is given to the surface effects on the performance of the energy harvesters. It is found that the surface effects are sensitive to the beam geometries and the surface material constants, and the effect of residual surface stress is more significant than that of the surface elasticity and the surface piezoelectricity. The axial deformation of the beam is also considered in the model to account for the electromechanical coupling due to piezoelectricity, and results indicate that piezoelectricity will diminish the output electrical quantities for the case investigated. This work could lead to the development of flexoelectric energy harvesters that can make the micro- and nanoscale sensor systems autonomous.

  10. Empirical model for estimating the surface roughness of machined ...

    African Journals Online (AJOL)

    Michael Horsfall

    Regression Analysis to construct a prediction model for surface roughness such that once the process parameters (cutting speed, feed, depth of cut, Nose. Radius and Speed) are given, the surface roughness can be predicted. The work piece material was EN8 which was processed by carbide-inserted tool conducted on ...

  11. A tri-objective, dynamic weapon assignment model for surface ...

    African Journals Online (AJOL)

    2015-05-11

    May 11, 2015 ... of available surface-based weapon systems to engage aerial threats in an attempt to protect defended surface ...... time stages to include in the fixed mean calculation in (2) be fixed to the minimum length of a FW. ... to solve the model in 139 seconds on an Intel Core i7-4770 processor with 8GB of random.

  12. Mathematical and computer modeling of component surface shaping

    Science.gov (United States)

    Lyashkov, A.

    2016-04-01

    The process of shaping technical surfaces is an interaction of a tool (a shape element) and a component (a formable element or a workpiece) in their relative movements. It was established that the main objects of formation are: 1) a discriminant of a surfaces family, formed by the movement of the shape element relatively the workpiece; 2) an enveloping model of the real component surface obtained after machining, including transition curves and undercut lines; 3) The model of cut-off layers obtained in the process of shaping. When modeling shaping objects there are a lot of insufficiently solved or unsolved issues that make up a single scientific problem - a problem of qualitative shaping of the surface of the tool and then the component surface produced by this tool. The improvement of known metal-cutting tools, intensive development of systems of their computer-aided design requires further improvement of the methods of shaping the mating surfaces. In this regard, an important role is played by the study of the processes of shaping of technical surfaces with the use of the positive aspects of analytical and numerical mathematical methods and techniques associated with the use of mathematical and computer modeling. The author of the paper has posed and has solved the problem of development of mathematical, geometric and algorithmic support of computer-aided design of cutting tools based on computer simulation of the shaping process of surfaces.

  13. Land surface Verification Toolkit (LVT) - a generalized framework for land surface model evaluation

    Science.gov (United States)

    Kumar, S. V.; Peters-Lidard, C. D.; Santanello, J.; Harrison, K.; Liu, Y.; Shaw, M.

    2012-06-01

    Model evaluation and verification are key in improving the usage and applicability of simulation models for real-world applications. In this article, the development and capabilities of a formal system for land surface model evaluation called the Land surface Verification Toolkit (LVT) is described. LVT is designed to provide an integrated environment for systematic land model evaluation and facilitates a range of verification approaches and analysis capabilities. LVT operates across multiple temporal and spatial scales and employs a large suite of in-situ, remotely sensed and other model and reanalysis datasets in their native formats. In addition to the traditional accuracy-based measures, LVT also includes uncertainty and ensemble diagnostics, information theory measures, spatial similarity metrics and scale decomposition techniques that provide novel ways for performing diagnostic model evaluations. Though LVT was originally designed to support the land surface modeling and data assimilation framework known as the Land Information System (LIS), it supports hydrological data products from non-LIS environments as well. In addition, the analysis of diagnostics from various computational subsystems of LIS including data assimilation, optimization and uncertainty estimation are supported within LVT. Together, LIS and LVT provide a robust end-to-end environment for enabling the concepts of model data fusion for hydrological applications. The evolving capabilities of LVT framework are expected to facilitate rapid model evaluation efforts and aid the definition and refinement of formal evaluation procedures for the land surface modeling community.

  14. Including Finite Surface Span Effects in Empirical Jet-Surface Interaction Noise Models

    Science.gov (United States)

    Brown, Clifford A.

    2016-01-01

    The effect of finite span on the jet-surface interaction noise source and the jet mixing noise shielding and reflection effects is considered using recently acquired experimental data. First, the experimental setup and resulting data are presented with particular attention to the role of surface span on far-field noise. These effects are then included in existing empirical models that have previously assumed that all surfaces are semi-infinite. This extended abstract briefly describes the experimental setup and data leaving the empirical modeling aspects for the final paper.

  15. Microwave Remote Sensing Modeling of Ocean Surface Salinity and Winds Using an Empirical Sea Surface Spectrum

    Science.gov (United States)

    Yueh, Simon H.

    2004-01-01

    Active and passive microwave remote sensing techniques have been investigated for the remote sensing of ocean surface wind and salinity. We revised an ocean surface spectrum using the CMOD-5 geophysical model function (GMF) for the European Remote Sensing (ERS) C-band scatterometer and the Ku-band GMF for the NASA SeaWinds scatterometer. The predictions of microwave brightness temperatures from this model agree well with satellite, aircraft and tower-based microwave radiometer data. This suggests that the impact of surface roughness on microwave brightness temperatures and radar scattering coefficients of sea surfaces can be consistently characterized by a roughness spectrum, providing physical basis for using combined active and passive remote sensing techniques for ocean surface wind and salinity remote sensing.

  16. Microscopic Analysis and Modeling of Airport Surface Sequencing, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Although a number of airportal surface models exist and have been successfully used for analysis of airportal operations, only recently has it become possible to...

  17. Surface Ship Shock Modeling and Simulation: Two-Dimensional Analysis

    Directory of Open Access Journals (Sweden)

    Young S. Shin

    1998-01-01

    Full Text Available The modeling and simulation of the response of a surface ship system to underwater explosion requires an understanding of many different subject areas. These include the process of underwater explosion events, shock wave propagation, explosion gas bubble behavior and bubble-pulse loading, bulk and local cavitation, free surface effect, fluid-structure interaction, and structural dynamics. This paper investigates the effects of fluid-structure interaction and cavitation on the response of a surface ship using USA-NASTRAN-CFA code. First, the one-dimensional Bleich-Sandler model is used to validate the approach, and second, the underwater shock response of a two-dimensional mid-section model of a surface ship is predicted with a surrounding fluid model using a constitutive equation of a bilinear fluid which does not allow transmission of negative pressures.

  18. Source Term Model for Fine Particle Resuspension from Indoor Surfaces

    National Research Council Canada - National Science Library

    Kim, Yoojeong; Gidwani, Ashok; Sippola, Mark; Sohn, Chang W

    2008-01-01

    This Phase I effort developed a source term model for particle resuspension from indoor surfaces to be used as a source term boundary condition for CFD simulation of particle transport and dispersion in a building...

  19. Modeling of liquid flow in surface discontinuities

    Science.gov (United States)

    Lobanova, I. S.; Meshcheryakov, V. A.; Kalinichenko, A. N.

    2018-01-01

    Polymer composite and metallic materials have found wide application in various industries such as aviation, rocket, car manufacturing, ship manufacturing, etc. Many design elements need permanent quality control. Ensuring high quality and reliability of products is impossible without effective nondestructive testing methods. One of these methods is penetrant testing using penetrating substances based on liquid penetration into defect cavities. In this paper, we propose a model of liquid flow to determine the rates of filling the defect cavities with various materials and, based on this, to choose optimal control modes.

  20. A model of the ground surface temperature for micrometeorological analysis

    Science.gov (United States)

    Leaf, Julian S.; Erell, Evyatar

    2017-07-01

    Micrometeorological models at various scales require ground surface temperature, which may not always be measured in sufficient spatial or temporal detail. There is thus a need for a model that can calculate the surface temperature using only widely available weather data, thermal properties of the ground, and surface properties. The vegetated/permeable surface energy balance (VP-SEB) model introduced here requires no a priori knowledge of soil temperature or moisture at any depth. It combines a two-layer characterization of the soil column following the heat conservation law with a sinusoidal function to estimate deep soil temperature, and a simplified procedure for calculating moisture content. A physically based solution is used for each of the energy balance components allowing VP-SEB to be highly portable. VP-SEB was tested using field data measuring bare loess desert soil in dry weather and following rain events. Modeled hourly surface temperature correlated well with the measured data (r 2 = 0.95 for a whole year), with a root-mean-square error of 2.77 K. The model was used to generate input for a pedestrian thermal comfort study using the Index of Thermal Stress (ITS). The simulation shows that the thermal stress on a pedestrian standing in the sun on a fully paved surface, which may be over 500 W on a warm summer day, may be as much as 100 W lower on a grass surface exposed to the same meteorological conditions.

  1. Biological Surface Adsorption Index of Nanomaterials: Modelling Surface Interactions of Nanomaterials with Biomolecules.

    Science.gov (United States)

    Chen, Ran; Riviere, Jim E

    2017-01-01

    Quantitative analysis of the interactions between nanomaterials and their surrounding environment is crucial for safety evaluation in the application of nanotechnology as well as its development and standardization. In this chapter, we demonstrate the importance of the adsorption of surrounding molecules onto the surface of nanomaterials by forming biocorona and thus impact the bio-identity and fate of those materials. We illustrate the key factors including various physical forces in determining the interaction happening at bio-nano interfaces. We further discuss the mathematical endeavors in explaining and predicting the adsorption phenomena, and propose a new statistics-based surface adsorption model, the Biological Surface Adsorption Index (BSAI), to quantitatively analyze the interaction profile of surface adsorption of a large group of small organic molecules onto nanomaterials with varying surface physicochemical properties, first employing five descriptors representing the surface energy profile of the nanomaterials, then further incorporating traditional semi-empirical adsorption models to address concentration effects of solutes. These Advancements in surface adsorption modelling showed a promising development in the application of quantitative predictive models in biological applications, nanomedicine, and environmental safety assessment of nanomaterials.

  2. Wetting kinetics of oil mixtures on fluorinated model cellulose surfaces.

    Science.gov (United States)

    Aulin, Christian; Shchukarev, Andrei; Lindqvist, Josefina; Malmström, Eva; Wågberg, Lars; Lindström, Tom

    2008-01-15

    The wetting of two different model cellulose surfaces has been studied; a regenerated cellulose (RG) surface prepared by spin-coating, and a novel multilayer film of poly(ethyleneimine) and a carboxymethylated microfibrillated cellulose (MFC). The cellulose films were characterized in detail using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM indicates smooth and continuous films on a nanometer scale and the RMS roughness of the RG cellulose and MFC surfaces was determined to be 3 and 6 nm, respectively. The cellulose films were modified by coating with various amounts of an anionic fluorosurfactant, perfluorooctadecanoic acid, or covalently modified with pentadecafluorooctanyl chloride. The fluorinated cellulose films were used to follow the spreading mechanisms of three different oil mixtures. The viscosity and surface tension of the oils were found to be essential parameters governing the spreading kinetics on these surfaces. XPS and dispersive surface energy measurements were made on the cellulose films coated with perfluorooctadecanoic acid. A strong correlation was found between the surface concentration of fluorine, the dispersive surface energy and the contact angle of castor oil on the surface. A dispersive surface energy less than 18 mN/m was required in order for the cellulose surface to be non-wetting (theta e>90 degrees ) by castor oil.

  3. Isospin breaking and radiative corrections in K{sub l4} decays; Brisure d'isospin et corrections radiatives au processus K{sub l4}

    Energy Technology Data Exchange (ETDEWEB)

    Cuplov, V

    2004-04-15

    This thesis is dedicated to the impact of electromagnetic corrections on the decays of K{sub l4}. 2 types of electromagnetic contributions have to be considered: first the exchange of virtual photons and secondly the non-perturbative part of meson-photon interactions. We have also considered the effects of isospin breaking. We have shown that the isospin breaking and the electromagnetic corrections affect K{sub l4} decays in the neutral and mixed channels (respectively by 8% and -2%), while the charged channel is unaffected. It also appears that the tree approximation for the computation of the decay rates, is not accurate enough to explain experimental data. In the second part of this work, we give the analytical expressions of the F and G form factors associated with the amplitude of the K{sub l4} process in the charged mode. Infra-red divergencies counterbalance each other in the decay rates calculation when we consider the process K{sub l4{gamma}} where 1 photon is emitted with an energy below the sensitivity of the detector. We have found that the calculation in one loop order represents 75% of the measured value. The impact of radiative corrections is about 0.9% while the isospin breaking effect is about 1.6 per cent.

  4. Summary and evaluation: fuel dynamics loss-of-flow experiments (tests L2, L3, and L4)

    International Nuclear Information System (INIS)

    Barts, E.W.; Deitrich, L.W.; Eberhart, J.G.; Fischer, A.K.; Meek, C.C.

    1975-09-01

    Three similar experiments conducted to support the analyses of hypothetical LMFBR unprotected-loss-of-flow accidents are summarized and evaluated. The tests, designated L2, L3, and L4, provided experimental data against which accident-analysis codes could be compared, so as to guide further analysis and modeling of the initiating phases of the hypothetical accident. The tests were conducted using seven-pin bundles of mixed-oxide fuel pins in Mark-II flowing-sodium loops in the TREAT reactor. Test L2 used fresh fuel. Tests L3 and L4 used irradiated fuel pins having, respectively, ''intermediate-power'' (no central void) and ''high-power'' (fully developed central void) microstructure. 12 references

  5. Alternative methods to model frictional contact surfaces using NASTRAN

    Science.gov (United States)

    Hoang, Joseph

    1992-01-01

    Elongated (slotted) holes have been used extensively for the integration of equipment into Spacelab racks. In the past, this type of interface has been modeled assuming that there is not slippage between contact surfaces, or that there is no load transfer in the direction of the slot. Since the contact surfaces are bolted together, the contact friction provides a load path determined by the normal applied force (bolt preload) and the coefficient of friction. Three alternate methods that utilize spring elements, externally applied couples, and stress dependent elements are examined to model the contacted surfaces. Results of these methods are compared with results obtained from methods that use GAP elements and rigid elements.

  6. A discrete surface growth model for two components

    International Nuclear Information System (INIS)

    El-Nashar, H.F.; Cerdeira, H.A.

    2000-04-01

    We present a ballistic deposition model for the surface growth of a binary species A and C. Numerical simulations of the growth kinetics show a deviation from the Kardar-Parisi-Zhang universality class, model valid for only one kind of deposited particles. The study also shows that when the deposition of particles with less active bonds occurs more frequently the voids under the surface become relevant. However, the increase in overhang/voids processes under the moving interface does not strengthen greatly the local surface gradient. (author)

  7. Lectures on Modification, Characterization and Modeling of Surfaces. Vol. I

    International Nuclear Information System (INIS)

    1997-01-01

    The field of surfaces and thin films is now so broad that has applications in protective coatings, electronic devices, displays, sensors, optical equipment, bio-compatible coatings for surgical implants, odontological and cardiovascular use, and numerous other technologies that depend on the deposition processes. Even though there exist well established methods for both, production and characterization of high-quality surfaces, the interest in finding alternative methods more reliable and less expensive is one of the challenges of present technologies. In this special issue the attention is focused on some areas concerning surface modification, characterization and modeling of surfaces. The volume contains reviews and articles on plasma processing, nitriding, nitrocarburising, diamond-like films, laser and ion-beam surface modification,texture in films and coatings, nuclear techniques in surface analysis, electron spectroscopies, ion scattering spectroscopy, secondary ion mass spectroscopy, STM and AFM applications to surface science, nano structure preparation magnetic and electric properties, surface modeling, calculation of electric and magnetic properties, statistical thermodynamics of surfaces

  8. Integrated Surface/subsurface flow modeling in PFLOTRAN

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Scott L [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    Understanding soil water, groundwater, and shallow surface water dynamics as an integrated hydrological system is critical for understanding the Earth’s critical zone, the thin outer layer at our planet’s surface where vegetation, soil, rock, and gases interact to regulate the environment. Computational tools that take this view of soil moisture and shallow surface flows as a single integrated system are typically referred to as integrated surface/subsurface hydrology models. We extend the open-source, highly parallel, subsurface flow and reactive transport simulator PFLOTRAN to accommodate surface flows. In contrast to most previous implementations, we do not represent a distinct surface system. Instead, the vertical gradient in hydraulic head at the land surface is neglected, which allows the surface flow system to be eliminated and incorporated directly into the subsurface system. This tight coupling approach leads to a robust capability and also greatly simplifies implementation in existing subsurface simulators such as PFLOTRAN. Successful comparisons to independent numerical solutions build confidence in the approximation and implementation. Example simulations of the Walker Branch and East Fork Poplar Creek watersheds near Oak Ridge, Tennessee demonstrate the robustness of the approach in geometrically complex applications. The lack of a robust integrated surface/subsurface hydrology capability had been a barrier to PFLOTRAN’s use in critical zone studies. This work addresses that capability gap, thus enabling PFLOTRAN as a community platform for building integrated models of the critical zone.

  9. A spatial and temporal continuous surface-subsurface hydrologic model

    Science.gov (United States)

    Xiao, Qing-Fu; Ustin, Susan L.; Wallender, Wesley W.

    1996-12-01

    A hydrologic model integrating surface-subsurface processes was developed based on spatial and temporal continuity theory. The raster-based mass balance hydrologic model consists of several submodels which determine spatial and temporal patterns in precipitation, surface flow, infiltration, subsurface flow, and the linkages between these submodels. Model parameters and variables are derived directly or indirectly from satellite remote sensing data, topographic maps, soil maps, literature, and weather station data and are stored in a Geographic Information System (GIS) database used for visualization. Surface resolution of cells in the model is 20 m by 20 m (pixel resolution of the Systeme Probatoire d'Observation de la Terre (SPOT) satellite image) over a 2511 km2 study area around the Crazy Mountains, Alaska, a watershed on the Arctic Circle draining into the Yukon River. The outputs from this model illustrate the interaction of physical and biologic factors on the partitioning of hydrologic components in a complex landscape.

  10. Modeling Apple Surface Temperature Dynamics Based on Weather Data

    Directory of Open Access Journals (Sweden)

    Lei Li

    2014-10-01

    Full Text Available The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed was recorded for seven hours between 11:00–18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of “Fuji” apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management.

  11. Adhesion of perfume-filled microcapsules to model fabric surfaces.

    Science.gov (United States)

    He, Yanping; Bowen, James; Andrews, James W; Liu, Min; Smets, Johan; Zhang, Zhibing

    2014-01-01

    The retention and adhesion of melamine formaldehyde (MF) microcapsules on a model fabric surface in aqueous solution were investigated using a customised flow chamber technique and atomic force microscopy (AFM). A cellulose film was employed as a model fabric surface. Modification of the cellulose with chitosan was found to increase the retention and adhesion of microcapsules on the model fabric surface. The AFM force-displacement data reveal that bridging forces resulting from the extension of cellulose chains dominate the adhesion between the microcapsule and the unmodified cellulose film, whereas electrostatic attraction helps the microcapsules adhere to the chitosan-modified cellulose film. The correlation between results obtained using these two complementary techniques suggests that the flow chamber device can be potentially used for rapid screening of the effect of chemical modification on the adhesion of microparticles to surfaces, reducing the time required to achieve an optimal formulation.

  12. A physically based model of global freshwater surface temperature

    Science.gov (United States)

    van Beek, Ludovicus P. H.; Eikelboom, Tessa; van Vliet, Michelle T. H.; Bierkens, Marc F. P.

    2012-09-01

    Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5° on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for

  13. Standard fire behavior fuel models: a comprehensive set for use with Rothermel's surface fire spread model

    Science.gov (United States)

    Joe H. Scott; Robert E. Burgan

    2005-01-01

    This report describes a new set of standard fire behavior fuel models for use with Rothermel's surface fire spread model and the relationship of the new set to the original set of 13 fire behavior fuel models. To assist with transition to using the new fuel models, a fuel model selection guide, fuel model crosswalk, and set of fuel model photos are provided.

  14. Surface-source modeling and estimation using biomagnetic measurements.

    Science.gov (United States)

    Yetik, Imam Samil; Nehorai, Arye; Muravchik, Carlos H; Haueisen, Jens; Eiselt, Michael

    2006-10-01

    We propose a number of electric source models that are spatially distributed on an unknown surface for biomagnetism. These can be useful to model, e.g., patches of electrical activity on the cortex. We use a realistic head (or another organ) model and discuss the special case of a spherical head model with radial sensors resulting in more efficient computations of the estimates for magnetoencephalography. We derive forward solutions, maximum likelihood (ML) estimates, and Cramér-Rao bound (CRB) expressions for the unknown source parameters. A model selection method is applied to decide on the most appropriate model. We also present numerical examples to compare the performances and computational costs of the different models and illustrate when it is possible to distinguish between surface and focal sources or line sources. Finally, we apply our methods to real biomagnetic data of phantom human torso and demonstrate the applicability of them.

  15. Estimation of shape model parameters for 3D surfaces

    DEFF Research Database (Denmark)

    Erbou, Søren Gylling Hemmingsen; Darkner, Sune; Fripp, Jurgen

    2008-01-01

    is applied to a database of 3D surfaces from a section of the porcine pelvic bone extracted from 33 CT scans. A leave-one-out validation shows that the parameters of the first 3 modes of the shape model can be predicted with a mean difference within [-0.01,0.02] from the true mean, with a standard deviation......Statistical shape models are widely used as a compact way of representing shape variation. Fitting a shape model to unseen data enables characterizing the data in terms of the model parameters. In this paper a Gauss-Newton optimization scheme is proposed to estimate shape model parameters of 3D...... surfaces using distance maps, which enables the estimation of model parameters without the requirement of point correspondence. For applications with acquisition limitations such as speed and cost, this formulation enables the fitting of a statistical shape model to arbitrarily sampled data. The method...

  16. The Blake-Zisserman model for digital surface models segmentation

    Directory of Open Access Journals (Sweden)

    M. Zanetti

    2013-10-01

    Full Text Available The Blake-Zisserman functional is a second-order variational model for data segmentation. The model is build up of several terms, the nature and the interaction of them allow to obtain a smooth approximation of the data that preserves the constant-gradient areas morphology, which are explicitly detected by partitioning the data with the graph of two special functions: the edge-detector function, which detects discontinuities of the datum, and the edge/crease-detector function, which also detects discontinuities of the gradient. First, the main features of the model are presented to justify the sense of the application of the model to DSMs. It is stressed the fact that the model can yield an almost piecewise-linear approximation of the data. This result is certainly of some interest for the specific application of the model to urban DSMs. Then, an example of its application is presented and the results are discussed to highlight how the features of the model affect the model outputs. The smooth approximation of the data produced by the model is thought to be a better candidate for further processing. In this sense, the application of the Blake-Zisserman model can be seen as a useful preprocessing step in the chain of DSMs processing. Eventually, some perspectives are presented to show some promising applications and developments of the Blake-Zisserman model.

  17. Modeling and analysis for surface roughness and material removal ...

    African Journals Online (AJOL)

    user

    terms of cutting parameters is also developed using regression modeling. The results indicate that the developed model is suitable for prediction of surface roughness and material removal rate in machining of unidirectional glass fiber reinforced plastics (UD-GFRP) composites. The predicted values and measured values ...

  18. Modeling Alaska boreal forests with a controlled trend surface approach

    Science.gov (United States)

    Mo Zhou; Jingjing Liang

    2012-01-01

    An approach of Controlled Trend Surface was proposed to simultaneously take into consideration large-scale spatial trends and nonspatial effects. A geospatial model of the Alaska boreal forest was developed from 446 permanent sample plots, which addressed large-scale spatial trends in recruitment, diameter growth, and mortality. The model was tested on two sets of...

  19. Modelling surface run-off and trends analysis over India

    Indian Academy of Sciences (India)

    responsible for run-off generation plays a major role in run-off modelling at region scales. Remote sensing, GIS and advancement of the computer technology based evaluation of land surface prop- erties at spatial and temporal scales are very useful input data for hydrological models. Using remote sensing data is not only ...

  20. Modeling and analysis for surface roughness and material removal ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... A multiple objective utility model has been studied to optimize both the dependent parameters. ... Keywords: UD-GFRP composites, ANOVA, multi response optimization, utility concept, regression modeling, surface roughness, material removal rate, ...

  1. Modified Critical State Two-Surface Plasticity Model for Sands

    DEFF Research Database (Denmark)

    Sørensen, Kris Wessel; Nielsen, Søren Kjær; Shajarati, Amir

    This article describes the outline of a numerical integration scheme for a critical state two-surface plasticity model for sands. The model is slightly modified by LeBlanc (2008) compared to the original formulation presented by Manzari and Dafalias (1997) and has the ability to correctly model...... the stress-strain response of sands. The model is versatile and can be used to simulate drained and undrained conditions, due to the fact that the model can efficiently calculate change in void ratio as well as pore pressure. The objective of the constitutive model is to investigate if the numerical...

  2. EX1504L4 Dive03 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  3. EX1504L4 Dive02 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  4. EX1504L4 Dive12 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  5. EX1504L4 Dive06 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  6. EX1504L4 Dive10 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  7. A Real-Time Programmer's Tour of General-Purpose L4 Microkernels

    Directory of Open Access Journals (Sweden)

    Ruocco Sergio

    2008-01-01

    Full Text Available Abstract L4-embedded is a microkernel successfully deployed in mobile devices with soft real-time requirements. It now faces the challenges of tightly integrated systems, in which user interface, multimedia, OS, wireless protocols, and even software-defined radios must run on a single CPU. In this paper we discuss the pros and cons of L4-embedded for real-time systems design, focusing on the issues caused by the extreme speed optimisations it inherited from its general-purpose ancestors. Since these issues can be addressed with a minimal performance loss, we conclude that, overall, the design of real-time systems based on L4-embedded is possible, and facilitated by a number of design features unique to microkernels and the L4 family.

  8. SMAP L4 Global Daily 9 km Carbon Net Ecosystem Exchange V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The Level-4 (L4) carbon product (SPL4CMDL) provides global gridded daily estimates of net ecosystem carbon (CO2) exchange derived using a satellite data based...

  9. EX0909L4 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0909L4: Mapping Field Trials -...

  10. EX1504L4 Dive04 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  11. Trojan asteroids - Populations, dynamical structure and origin of the L4 and L5 swarms

    International Nuclear Information System (INIS)

    Shoemaker, E.M.; Shoemaker, C.S.; Wolfe, R.F.

    1989-01-01

    The origin of Trojan asteroids, their populations, and dynamical structures are examined. Data available of Trojan asteroids reveal that the total population of Trojans of greater than 15-km diam is roughly half that estimated for the main-belt asteroids. Two-thirds of the known Trojans are in the L4 swarm. Bright Trojans are as numerous in the L5 swarm as in L4 swarm, but faint L5 Trojans are only half as numerous. Similarities of characteristic orbital parameters among certain Trojans indicate the presence of five and possibly as many as eight collisional groups in the L4 swarm. It is suggested that the magnitude distribution of L4 Trojans is probably a result of strong collisional evolution. It is suggested that the present Trojans are chiefly fragments of Jupiter planetesimals that were captured during an episode of heavy flux near Jupiter during the dispersal of the planetesimal swarm. 40 refs

  12. EX1504L4 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1504L4: Campaign to Address Pacific...

  13. EX1504L4 Dive01 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  14. EX1504L4 Dive05 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  15. EX1504L4 Dive09 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  16. EX1504L4 Dive11 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  17. EX1504L4 Dive13 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  18. EX1504L4 Dive08 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  19. EX1504L4 Dive07 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L4: Campaign to Address...

  20. A 2-D model for friction of complex anisotropic surfaces

    Science.gov (United States)

    Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M.

    2018-03-01

    The friction force observed at macroscale is the result of interactions at various lower length scales that are difficult to model in a combined manner. For this reason, simplified approaches are required, depending on the specific aspect to be investigated. In particular, the dimensionality of the system is often reduced, especially in models designed to provide a qualitative description of frictional properties of elastic materials, e.g. the spring-block model. In this paper, we implement for the first time a two dimensional extension of the spring-block model, applying it to structured surfaces and investigating by means of numerical simulations the frictional behaviour of a surface in the presence of features like cavities, pillars or complex anisotropic structures. We show how friction can be effectively tuned by appropriate design of such surface features.

  1. Scale-adaptive surface modeling of vascular structures

    Directory of Open Access Journals (Sweden)

    Ma Xin

    2010-11-01

    Full Text Available Abstract Background The effective geometric modeling of vascular structures is crucial for diagnosis, therapy planning and medical education. These applications require good balance with respect to surface smoothness, surface accuracy, triangle quality and surface size. Methods Our method first extracts the vascular boundary voxels from the segmentation result, and utilizes these voxels to build a three-dimensional (3D point cloud whose normal vectors are estimated via covariance analysis. Then a 3D implicit indicator function is computed from the oriented 3D point cloud by solving a Poisson equation. Finally the vessel surface is generated by a proposed adaptive polygonization algorithm for explicit 3D visualization. Results Experiments carried out on several typical vascular structures demonstrate that the presented method yields both a smooth morphologically correct and a topologically preserved two-manifold surface, which is scale-adaptive to the local curvature of the surface. Furthermore, the presented method produces fewer and better-shaped triangles with satisfactory surface quality and accuracy. Conclusions Compared to other state-of-the-art approaches, our method reaches good balance in terms of smoothness, accuracy, triangle quality and surface size. The vessel surfaces produced by our method are suitable for applications such as computational fluid dynamics simulations and real-time virtual interventional surgery.

  2. Surface Winds and Dust Biases in Climate Models

    Science.gov (United States)

    Evan, A. T.

    2018-01-01

    An analysis of North African dust from models participating in the Fifth Climate Models Intercomparison Project (CMIP5) suggested that, when forced by observed sea surface temperatures, these models were unable to reproduce any aspects of the observed year-to-year variability in dust from North Africa. Consequently, there would be little reason to have confidence in the models' projections of changes in dust over the 21st century. However, no subsequent study has elucidated the root causes of the disagreement between CMIP5 and observed dust. Here I develop an idealized model of dust emission and then use this model to show that, over North Africa, such biases in CMIP5 models are due to errors in the surface wind fields and not due to the representation of dust emission processes. These results also suggest that because the surface wind field over North Africa is highly spatially autocorrelated, intermodel differences in the spatial structure of dust emission have little effect on the relative change in year-to-year dust emission over the continent. I use these results to show that similar biases in North African dust from the NASA Modern Era Retrospective analysis for Research and Applications (MERRA) version 2 surface wind field biases but that these wind biases were not present in the first version of MERRA.

  3. Modelling cell motility and chemotaxis with evolving surface finite elements.

    Science.gov (United States)

    Elliott, Charles M; Stinner, Björn; Venkataraman, Chandrasekhar

    2012-11-07

    We present a mathematical and a computational framework for the modelling of cell motility. The cell membrane is represented by an evolving surface, with the movement of the cell determined by the interaction of various forces that act normal to the surface. We consider external forces such as those that may arise owing to inhomogeneities in the medium and a pressure that constrains the enclosed volume, as well as internal forces that arise from the reaction of the cells' surface to stretching and bending. We also consider a protrusive force associated with a reaction-diffusion system (RDS) posed on the cell membrane, with cell polarization modelled by this surface RDS. The computational method is based on an evolving surface finite-element method. The general method can account for the large deformations that arise in cell motility and allows the simulation of cell migration in three dimensions. We illustrate applications of the proposed modelling framework and numerical method by reporting on numerical simulations of a model for eukaryotic chemotaxis and a model for the persistent movement of keratocytes in two and three space dimensions. Movies of the simulated cells can be obtained from http://homepages.warwick.ac.uk/∼maskae/CV_Warwick/Chemotaxis.html.

  4. Surface Structures of Model Metal Catalysts in Reactant Gases.

    Science.gov (United States)

    Tao, Franklin Feng; Ralston, Walter T; Liu, Huimin; Somorjai, Gabor A

    2018-01-18

    Atomic scale knowledge of the surface structure of a metal catalyst is essential for fundamentally understanding the catalytic reactions performed on it. A correlation between the true atomic surface structure of a metal catalyst under reaction conditions and the corresponding catalytic performance is the key in pursuing mechanistic insight at a molecular level. Here the surface structures of model, metal catalysts in both ultrahigh vacuum (UHV) and gaseous environments of CO at a wide range of pressures are discussed. The complexity of observed surface structures in CO is illustrated, driving the necessity for visualization of the catalytic metals under realistic reaction conditions. Technical barriers for visualization of metal surfaces in situ at high temperature and high pressure are discussed.

  5. Assessment of Response Surface Models using Independent Confirmation Point Analysis

    Science.gov (United States)

    DeLoach, Richard

    2010-01-01

    This paper highlights various advantages that confirmation-point residuals have over conventional model design-point residuals in assessing the adequacy of a response surface model fitted by regression techniques to a sample of experimental data. Particular advantages are highlighted for the case of design matrices that may be ill-conditioned for a given sample of data. The impact of both aleatory and epistemological uncertainty in response model adequacy assessments is considered.

  6. Modelling of frost formation and growth on microstuctured surface

    Science.gov (United States)

    Muntaha, Md. Ali; Haider, Md. Mushfique; Rahman, Md. Ashiqur

    2016-07-01

    Frost formation on heat exchangers is an undesirable phenomenon often encountered in different applications where the cold surface with a temperature below freezing point of water is exposed to humid air. The formation of frost on the heat transfer surface results in an increase in pressure drop and reduction in heat transfer, resulting in a reduction of the system efficiency. Many factors, including the temperature and moisture content of air, cold plate temperature, surface wettability etc., are known to affect frost formation and growth. In our present study, a model for frost growth on rectangular, periodic microgroove surfaces for a range of microgroove dimension (ten to hundreds of micron) is presented. The mathematical model is developed analytically by solving the governing heat and mass transfer equations with appropriate boundary conditions using the EES (Engineering Equation Solver) software. For temperature, a convective boundary condition at frost-air interface and a fixed cold plate surface temperature is used. Instead of considering the saturation or super-saturation models, density gradient at the surface is obtained by considering experimentally-found specified heat flux. The effect of surface wettability is incorporated by considering the distribution of condensed water droplets at the early stage of frost formation. Thickness, density and thermal conductivity of frost layer on the micro-grooved surfaces are found to vary with the dimension of the grooves. The variation of density and thickness of the frost layer on these micro-grooved surfaces under natural convection is numerally determined for a range of plate temperature and air temperature conditions and is compared with experimental results found in the open literature.

  7. Surface photovoltage measurements and finite element modeling of SAW devices.

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, Christine

    2012-03-01

    Over the course of a Summer 2011 internship with the MEMS department of Sandia National Laboratories, work was completed on two major projects. The first and main project of the summer involved taking surface photovoltage measurements for silicon samples, and using these measurements to determine surface recombination velocities and minority carrier diffusion lengths of the materials. The SPV method was used to fill gaps in the knowledge of material parameters that had not been determined successfully by other characterization methods. The second project involved creating a 2D finite element model of a surface acoustic wave device. A basic form of the model with the expected impedance response curve was completed, and the model is ready to be further developed for analysis of MEMS photonic resonator devices.

  8. DNSC08 mean sea surface and mean dynamic topography models

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Knudsen, Per

    2009-01-01

    -2004. It is the first global MSS without a polar gap including all of the Arctic Ocean by including laser altimetry from the ICESat mission. The mean dynamic topography (MDT) is the quantity that bridges the geoid and the mean sea surface constraining large-scale ocean circulation. Here we present a new high...... models. This way a consistent modeling of the interannual sea level variability is carried out before different MSS and MDT models are compared. Altimetric derived physical MSS can be converted into an "inverse barometer corrected MSS'' by correcting the altimeter range for the inverse barometer effect......The Danish National Space Center data set DNSC08 mean sea surface (MSS) is a new enhanced mapping of the mean sea surface height of the worlds oceans, derived from a combination of 12 years of satellite altimetry from a total of eight different satellites covering the period 1993...

  9. TECHNICAL VISION SYSTEM FOR THE ROBOTIC MODEL OF SURFACE VESSEL

    Directory of Open Access Journals (Sweden)

    V. S. Gromov

    2016-07-01

    Full Text Available The paper presents results of work on creation of technical vision systems within the training complex for the verification of control systems by the model of surface vessel. The developed system allows determination of the coordinates and orientation angle of the object of control by means of an external video camera on one bench mark and without the need to install additional equipment on the object of control itself. Testing of the method was carried out on the robotic complex with the model of a surface vessel with a length of 430 mm; coordinates of the control object were determined with the accuracy of 2 mm. This method can be applied as a subsystem of receiving coordinates for systems of automatic control of surface vessels when testing on the scale models.

  10. Surface complexation modeling of americium sorption onto volcanic tuff.

    Science.gov (United States)

    Ding, M; Kelkar, S; Meijer, A

    2014-10-01

    Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways. Published by Elsevier Ltd.

  11. Sediment Transport Model for a Surface Irrigation System

    Directory of Open Access Journals (Sweden)

    Damodhara R. Mailapalli

    2013-01-01

    Full Text Available Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in furrow irrigation. The irrigation hydraulic model simulates flow in a furrow irrigation system using the analytically solved zero-inertial overland flow equations and 1D-Green-Ampt, 2D-Fok, and Kostiakov-Lewis infiltration equations. Performance of the sediment transport model was evaluated for bare and cropped furrow fields. The results indicated that the sediment transport model can predict the initial sediment rate adequately, but the simulated sediment rate was less accurate for the later part of the irrigation event. Sensitivity analysis of the parameters of the sediment module showed that the soil erodibility coefficient was the most influential parameter for determining sediment load in furrow irrigation. The developed modeling tool can be used as a water management tool for mitigating sediment loss from the surface irrigated fields.

  12. Improvement of a land surface model for accurate prediction of surface energy and water balances

    International Nuclear Information System (INIS)

    Katata, Genki

    2009-02-01

    In order to predict energy and water balances between the biosphere and atmosphere accurately, sophisticated schemes to calculate evaporation and adsorption processes in the soil and cloud (fog) water deposition on vegetation were implemented in the one-dimensional atmosphere-soil-vegetation model including CO 2 exchange process (SOLVEG2). Performance tests in arid areas showed that the above schemes have a significant effect on surface energy and water balances. The framework of the above schemes incorporated in the SOLVEG2 and instruction for running the model are documented. With further modifications of the model to implement the carbon exchanges between the vegetation and soil, deposition processes of materials on the land surface, vegetation stress-growth-dynamics etc., the model is suited to evaluate an effect of environmental loads to ecosystems by atmospheric pollutants and radioactive substances under climate changes such as global warming and drought. (author)

  13. Do Lateral Flows Matter for the Hyperresolution Land Surface Modeling?

    Science.gov (United States)

    Ji, Peng; Yuan, Xing; Liang, Xin-Zhong

    2017-11-01

    Hyperresolution land surface modeling provides an unprecedented opportunity to simulate locally relevant water and energy cycle, but lateral surface and/or subsurface flows that are essential at fine scale are often neglected by most one-dimensional land surface models (LSMs). To analyze effects of lateral flows across scales, a Conjunctive Surface-Subsurface Process model, which considers soil moisture-surface flow interaction and quasi-three-dimensional subsurface flow, is implemented over a mountainous HyperHydro test bed in southwestern USA at different resolutions. Validation over more than 70 International Soil Moisture Network stations shows that there are significant improvements in soil moisture simulations from 30 km to 4 km as finer soil property and precipitation data are used, with correlation increased by 5%-16% and error decreased by 5%. Lateral surface flow has a significant influence on surface soil moisture and ground evaporation even at coarse resolution. Effect of lateral subsurface flow on soil moisture is nontrivial at 1 km or finer resolution especially over wet areas. At 100 m resolution, topography-induced lateral subsurface flow causes drier peaks and wetter valleys, decreases latent heat by 8% at peaks, while increases it by 12% at valleys. Furthermore, influences of lateral subsurface flow on ground evaporation and vegetation transpiration are more significant during dry season due to a stronger coupling between soil moisture and evapotranspiration. Therefore, it is worthy to incorporate lateral flow processes in hyperresolution LSMs to better represent water and energy heterogeneity even with limited hyperresolution meteorological and surface data.

  14. Surface science studies of model fuel cell electrocatalysts

    Science.gov (United States)

    Marković, N. M.; Ross, P. N.

    2002-04-01

    The purpose of this review is to discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies. Pure metal single crystals and well-characterized bulk alloys have been used quite successfully as models for real (commercial) electrocatalysts. Given the sheer volume of all work in electrocatalysis that is on fuel cell reactions, we will focus on electrocatalysts for fuel cells. Since Pt is the model fuel cell electrocatalyst, we will focus entirely on studies of pure Pt and Pt bimetallic alloys. The electrode reactions discussed include hydrogen oxidation/evolution, oxygen reduction, and the electrooxidation of carbon monoxide, formic acid, and methanol. Surface spectroscopies emphasized are FTIR, STM/AFM and surface X-ray scattering (SXS). The discussion focuses on the relation between the energetics of adsorption of intermediates and the reaction pathway and kinetics, and how the energetics and kinetics relate to the extrinsic properties of the model system, e.g. surface structure and/or composition. Finally, we conclude by discussing the limitations that are reached by using pure metal single crystals and well-characterized bulk alloys as models for real catalysts, and suggest some directions for developing more realistic systems.

  15. Surface growth of two kinds of particles deposition models

    International Nuclear Information System (INIS)

    Wei Wang; Cerdeira, H.A.

    1993-10-01

    The surface kinetics with diffusion of two kinds of particles (A and C) deposition models, randomlike and ballisticlike depositing on a (1 + 1)-dimensional substrate, has been studied in this paper. The scaling behaviour of the surface width for these two models is obtained for various deposition probability P of particle C (the probability of particle A, being 1 - P). We found that both models have a scaling behaviour: the surface width growth only depends on the time, W ∼ t α(p) for the early stage and W ∼ t β(P) for the intermediate time, as well as W ∼ L z for the later time with different exponents α(P) and β(P) and z for two models. In addition, there is a phase transition when the saturation surface widths are scaled to the deposition probability P for both models W(t = ∞) ∼ P γ : before and after the transition the scaling exponent γ is different. This transition is interpreted as that there are different morphologic structures when the depositing probability for one kind of particle, particle C, is larger than a critical value P c . (author). 16 refs, 5 figs, 2 tabs

  16. A land surface scheme for atmospheric and hydrologic models: SEWAB (Surface Energy and Water Balance)

    Energy Technology Data Exchange (ETDEWEB)

    Mengelkamp, H.T.; Warrach, K.; Raschke, E. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

    1997-12-31

    A soil-vegetation-atmosphere-transfer scheme is presented here which solves the coupled system of the Surface Energy and Water Balance (SEWAB) equations considering partly vegetated surfaces. It is based on the one-layer concept for vegetation. In the soil the diffusion equations for heat and moisture are solved on a multi-layer grid. SEWAB has been developed to serve as a land-surface scheme for atmospheric circulation models. Being forced with atmospheric data from either simulations or measurements it calculates surface and subsurface runoff that can serve as input to hydrologic models. The model has been validated with field data from the FIFE experiment and has participated in the PILPS project for intercomparison of land-surface parameterization schemes. From these experiments we feel that SEWAB reasonably well partitions the radiation and precipitation into sensible and latent heat fluxes as well as into runoff and soil moisture Storage. (orig.) [Deutsch] Ein Landoberflaechenschema wird vorgestellt, das den Transport von Waerme und Wasser zwischen dem Erdboden, der Vegetation und der Atmosphaere unter Beruecksichtigung von teilweise bewachsenem Boden beschreibt. Im Erdboden werden die Diffusionsgleichungen fuer Waerme und Feuchte auf einem Gitter mit mehreren Schichten geloest. Das Schema SEWAB (Surface Energy and Water Balance) beschreibt die Landoberflaechenprozesse in atmosphaerischen Modellen und berechnet den Oberflaechenabfluss und den Basisabfluss, die als Eingabedaten fuer hydrologische Modelle genutzt werden koennen. Das Modell wurde mit Daten des FIFE-Experiments kalibriert und hat an Vergleichsexperimenten fuer Landoberflaechen-Schemata im Rahmen des PILPS-Projektes teilgenommen. Dabei hat sich gezeigt, dass die Aufteilung der einfallenden Strahlung und des Niederschlages in den sensiblen und latenten Waermefluss und auch in Abfluss und Speicherung der Bodenfeuchte in SEWAB den beobachteten Daten recht gut entspricht. (orig.)

  17. Exposing earth surface process model simulations to a large audience

    Science.gov (United States)

    Overeem, I.; Kettner, A. J.; Borkowski, L.; Russell, E. L.; Peddicord, H.

    2015-12-01

    The Community Surface Dynamics Modeling System (CSDMS) represents a diverse group of >1300 scientists who develop and apply numerical models to better understand the Earth's surface. CSDMS has a mandate to make the public more aware of model capabilities and therefore started sharing state-of-the-art surface process modeling results with large audiences. One platform to reach audiences outside the science community is through museum displays on 'Science on a Sphere' (SOS). Developed by NOAA, SOS is a giant globe, linked with computers and multiple projectors and can display data and animations on a sphere. CSDMS has developed and contributed model simulation datasets for the SOS system since 2014, including hydrological processes, coastal processes, and human interactions with the environment. Model simulations of a hydrological and sediment transport model (WBM-SED) illustrate global river discharge patterns. WAVEWATCH III simulations have been specifically processed to show the impacts of hurricanes on ocean waves, with focus on hurricane Katrina and super storm Sandy. A large world dataset of dams built over the last two centuries gives an impression of the profound influence of humans on water management. Given the exposure of SOS, CSDMS aims to contribute at least 2 model datasets a year, and will soon provide displays of global river sediment fluxes and changes of the sea ice free season along the Arctic coast. Over 100 facilities worldwide show these numerical model displays to an estimated 33 million people every year. Datasets storyboards, and teacher follow-up materials associated with the simulations, are developed to address common core science K-12 standards. CSDMS dataset documentation aims to make people aware of the fact that they look at numerical model results, that underlying models have inherent assumptions and simplifications, and that limitations are known. CSDMS contributions aim to familiarize large audiences with the use of numerical

  18. Validating modeled turbulent heat fluxes across large freshwater surfaces

    Science.gov (United States)

    Lofgren, B. M.; Fujisaki-Manome, A.; Gronewold, A.; Anderson, E. J.; Fitzpatrick, L.; Blanken, P.; Spence, C.; Lenters, J. D.; Xiao, C.; Charusambot, U.

    2017-12-01

    Turbulent fluxes of latent and sensible heat are important physical processes that influence the energy and water budgets of the Great Lakes. Validation and improvement of bulk flux algorithms to simulate these turbulent heat fluxes are critical for accurate prediction of hydrodynamics, water levels, weather, and climate over the region. Here we consider five heat flux algorithms from several model systems; the Finite-Volume Community Ocean Model, the Weather Research and Forecasting model, and the Large Lake Thermodynamics Model, which are used in research and operational environments and concentrate on different aspects of the Great Lakes' physical system, but interface at the lake surface. The heat flux algorithms were isolated from each model and driven by meteorological data from over-lake stations in the Great Lakes Evaporation Network. The simulation results were compared with eddy covariance flux measurements at the same stations. All models show the capacity to the seasonal cycle of the turbulent heat fluxes. Overall, the Coupled Ocean Atmosphere Response Experiment algorithm in FVCOM has the best agreement with eddy covariance measurements. Simulations with the other four algorithms are overall improved by updating the parameterization of roughness length scales of temperature and humidity. Agreement between modelled and observed fluxes notably varied with geographical locations of the stations. For example, at the Long Point station in Lake Erie, observed fluxes are likely influenced by the upwind land surface while the simulations do not take account of the land surface influence, and therefore the agreement is worse in general.

  19. Land-Surface-Atmosphere Coupling in Observations and Models

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2009-07-01

    Full Text Available The diurnal cycle and the daily mean at the land-surface result from the coupling of many physical processes. The framework of this review is largely conceptual; looking for relationships and information in the coupling of processes in models and observations. Starting from the surface energy balance, the role of the surface and cloud albedos in the shortwave and longwave fluxes is discussed. A long-wave radiative scaling of the diurnal temperature range and the night-time boundary layer is summarized. Several aspects of the local surface energy partition are presented: the role of soilwater availability and clouds; vector methods for understanding mixed layer evolution, and the coupling between surface and boundary layer that determines the lifting condensation level. Moving to larger scales, evaporation-precipitation feedback in models is discussed; and the coupling of column water vapor, clouds and precipitation to vertical motion and moisture convergence over the Amazon. The final topic is a comparison of the ratio of surface shortwave cloud forcing to the diabatic precipitation forcing of the atmosphere in ERA-40 with observations.

  20. Characterization, modeling and simulation of fused deposition modeling fabricated part surfaces

    Science.gov (United States)

    Taufik, Mohammad; Jain, Prashant K.

    2017-12-01

    Surface roughness is generally used for characterization, modeling and simulation of fused deposition modeling (FDM) fabricated part surfaces. But the average surface roughness is not able to provide the insight of surface characteristics with sharp peaks and deep valleys. It deals in the average sense for all types of surfaces, including FDM fabricated surfaces with distinct surface profile features. The present research work shows that kurtosis and skewness can be used for characterization, modeling and simulation of FDM surfaces because these roughness parameters have the ability to characterize a surface with sharp peaks and deep valleys. It can be critical in certain application areas in tribology and biomedicine, where the surface profile plays an important role. Thus, in this study along with surface roughness, skewness and kurtosis are considered to show a novel strategy to provide new transferable knowledge about FDM fabricated part surfaces. The results suggest that the surface roughness, skewness and kurtosis are significantly different at 0° and in the range (0°, 30°], [30°, 90°] of build orientation.

  1. Performance of fire behavior fuel models developed for the Rothermel Surface Fire Spread Model

    Science.gov (United States)

    Robert Ziel; W. Matt Jolly

    2009-01-01

    In 2005, 40 new fire behavior fuel models were published for use with the Rothermel Surface Fire Spread Model. These new models are intended to augment the original 13 developed in 1972 and 1976. As a compiled set of quantitative fuel descriptions that serve as input to the Rothermel model, the selected fire behavior fuel model has always been critical to the resulting...

  2. Stochastic Modeling and Deterministic Limit of Catalytic Surface Processes

    DEFF Research Database (Denmark)

    Starke, Jens; Reichert, Christian; Eiswirth, Markus

    2007-01-01

    Three levels of modeling, microscopic, mesoscopic and macroscopic are discussed for the CO oxidation on low-index platinum single crystal surfaces. The introduced models on the microscopic and mesoscopic level are stochastic while the model on the macroscopic level is deterministic. It can......, such that in contrast to the microscopic model the spatial resolution is reduced. The derivation of deterministic limit equations is in correspondence with the successful description of experiments under low-pressure conditions by deterministic reaction-diffusion equations while for intermediate pressures phenomena...

  3. Mathematical model of the metal mould surface temperature optimization

    International Nuclear Information System (INIS)

    Mlynek, Jaroslav; Knobloch, Roman; Srb, Radek

    2015-01-01

    The article is focused on the problem of generating a uniform temperature field on the inner surface of shell metal moulds. Such moulds are used e.g. in the automotive industry for artificial leather production. To produce artificial leather with uniform surface structure and colour shade the temperature on the inner surface of the mould has to be as homogeneous as possible. The heating of the mould is realized by infrared heaters located above the outer mould surface. The conceived mathematical model allows us to optimize the locations of infrared heaters over the mould, so that approximately uniform heat radiation intensity is generated. A version of differential evolution algorithm programmed in Matlab development environment was created by the authors for the optimization process. For temperate calculations software system ANSYS was used. A practical example of optimization of heaters locations and calculation of the temperature of the mould is included at the end of the article

  4. Mathematical modeling for surface hardness in investment casting applications

    International Nuclear Information System (INIS)

    Singh, Rupinder

    2012-01-01

    Investment casting (IC) has many potential engineering applications. Not much work hitherto has been reported for modeling the surface hardness (SH) in IC of industrial components. In the present study, outcome of Taguchi based macro model has been used for developing a mathematical model for SH; using Buckingham's π theorem. Three input parameters namely volume/surface area (V/A) ratio of cast components, slurry layer's combination (LC) and molten metal pouring temperature were selected to give output in form of SH. This study will provide main effects of these variables on SH and will shed light on the SH mechanism in IC. The comparison with experimental results will also serve as further validation of model

  5. Modeling the Soul Surface Seal from a Filtration Perspective

    Directory of Open Access Journals (Sweden)

    N.M. Somaratne

    1998-01-01

    Full Text Available A physically based model of soil surface scaling is proposed. The governing equations are formulated on the principle of conservation of mass assuming Darcy's law applies to suspension flowing through the soil surface. The model incorporates the physics of surface sealing by mechanisms that capture suspended particles moving with infiltrating water. As a result of particle retention in the soil system, the intrinsic porosity is reduced and hulk density is increased, resulting in changes to soil hydraulic properties such as moisture retention and hydraulic conductivity. Empirical functions are developed to describe the changes of these properties as the seal develops. With this approach, the seal can be mathematically described by well defined initial and boundary conditions and transient seal properties can be simulated in a physically realistic manner.

  6. Scattering of surface waves modelled by the integral equation method

    Science.gov (United States)

    Lu, Laiyu; Maupin, Valerie; Zeng, Rongsheng; Ding, Zhifeng

    2008-09-01

    The integral equation method is used to model the propagation of surface waves in 3-D structures. The wavefield is represented by the Fredholm integral equation, and the scattered surface waves are calculated by solving the integral equation numerically. The integration of the Green's function elements is given analytically by treating the singularity of the Hankel function at R = 0, based on the proper expression of the Green's function and the addition theorem of the Hankel function. No far-field and Born approximation is made. We investigate the scattering of surface waves propagating in layered reference models imbedding a heterogeneity with different density, as well as Lamé constant contrasts, both in frequency and time domains, for incident plane waves and point sources.

  7. Wetting and free surface flow modeling for potting and encapsulation.

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Carlton, F.; Brooks, Michael J. (Los Alamos National Laboratory, Los Alamos, NM); Graham, Alan Lyman (Los Alamos National Laboratory, Los Alamos, NM); Noble, David F. (David Frederick) (.; )); Notz, Patrick K.; Hopkins, Matthew Morgan; Castaneda, Jaime N.; Mahoney, Leo James (Kansas City Plant, Kansas City, MO); Baer, Thomas A.; Berchtold, Kathryn (Los Alamos National Laboratory, Los Alamos, NM); Adolf, Douglas Brian; Wilkes, Edward Dean; Rao, Rekha Ranjana; Givler, Richard C.; Sun, Amy Cha-Tien; Cote, Raymond O.; Mondy, Lisa Ann; Grillet, Anne Mary; Kraynik, Andrew Michael

    2007-06-01

    As part of an effort to reduce costs and improve quality control in encapsulation and potting processes the Technology Initiative Project ''Defect Free Manufacturing and Assembly'' has completed a computational modeling study of flows representative of those seen in these processes. Flow solutions are obtained using a coupled, finite-element-based, numerical method based on the GOMA/ARIA suite of Sandia flow solvers. The evolution of the free surface is solved with an advanced level set algorithm. This approach incorporates novel methods for representing surface tension and wetting forces that affect the evolution of the free surface. In addition, two commercially available codes, ProCAST and MOLDFLOW, are also used on geometries representing encapsulation processes at the Kansas City Plant. Visual observations of the flow in several geometries are recorded in the laboratory and compared to the models. Wetting properties for the materials in these experiments are measured using a unique flowthrough goniometer.

  8. Computational model of surface ablation from tokamak disruptions

    International Nuclear Information System (INIS)

    Ehst, D.; Hassanein, A.

    1993-10-01

    Energy transfer to material surfaces is dominated by photon radiation through low temperature plasma vapors if tokamak disruptions are due to low kinetic energy particles ( < 100 eV). Simple models of radiation transport are derived and incorporated into a fast-running computer routine to model this process. The results of simulations are in fair agreement with plasma gun erosion tests on several metal targets

  9. Optimized Model Surfaces for Advanced Atomic Force Microscopy Studies of Surface Nanobubbles.

    Science.gov (United States)

    Song, Bo; Zhou, Yi; Schönherr, Holger

    2016-11-01

    The formation of self-assembled monolayers (SAMs) of binary mixtures of 16-mercaptohexadecanoic acid (MHDA) and 1-octadecanethiol (ODT) on ultraflat template-stripped gold (TSG) surfaces was systematically investigated to clarify the assembly behavior, composition, and degree of possible phase segregation in light of atomic force microscopy (AFM) studies of surface nanobubbles on these substrates. The data for SAMs on TSG were compared to those obtained by adsorption on rough evaporated gold, as reported in a previous study. Quartz crystal microbalance and surface plasmon resonance data acquired in situ on TSG indicate that similar to SAM formation on conventional evaporated gold substrates ODT and MHDA form monolayers and bilayers, respectively. The second layer on MHDA, whose formation is attributed to hydrogen bonding, can be easily removed by adequate rinsing with water. The favorable agreement of the grazing incidence reflection Fourier transform infrared (GIR FTIR) spectroscopy and contact angle data analyzed with the Israelachvili-Gee model suggests that the binary SAMs do not segregate laterally. This conclusion is fully validated by high-resolution friction force AFM observations down to a length scale of 8-10 nm, which is much smaller than the typical observed surface nanobubble radii. Finally, correspondingly functionalized TSG substrates are shown to be valuable supports for studying surface nanobubbles by AFM in water and for addressing the relation between surface functionality and nanobubble formation and properties.

  10. Models for prediction of global solar radiation on horizontal surface ...

    African Journals Online (AJOL)

    The estimation of global solar radiation continues to play a fundamental role in solar engineering systems and applications. This paper compares various models for estimating the average monthly global solar radiation on horizontal surface for Akure, Nigeria, using solar radiation and sunshine duration data covering years ...

  11. Surface-complexation modelling for describing adsorption of ...

    African Journals Online (AJOL)

    2013-06-08

    Jun 8, 2013 ... Adsorption of dissolved phosphate onto synthetic hydrous ferric oxide (HFO) was measured in the laboratory as a function of pH, ionic strength, and phosphate relative concentration. Experimental data were used to constrain optimal values of surface complexation reactions using a geochemical modeling ...

  12. Modeling marine surface microplastic transport to assess optimal removal locations

    NARCIS (Netherlands)

    Sherman, Peter; Van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics

  13. Remote sensing estimates of impervious surfaces for pluvial flood modelling

    DEFF Research Database (Denmark)

    Kaspersen, Per Skougaard; Drews, Martin

    This paper investigates the accuracy of medium resolution (MR) satellite imagery in estimating impervious surfaces for European cities at the detail required for pluvial flood modelling. Using remote sensing techniques enables precise and systematic quantification of the influence of the past 30...

  14. Infrared Analysis Of Enzymes Adsorbed Onto Model Surfaces

    Science.gov (United States)

    Story, Gloria M.; Rauch, Deborah S.; Brode, Philip F.; Marcott, Curtis A.

    1989-12-01

    The adsorption of the enzymes, subtilisin BPN' and lysozyme, onto model surfaces was examined using attenuated total reflectance (ATR) infrared (IR) spectroscopy. Using a cylindrical internal reflection (CIRcle) cell with a Germanium (Ge) internal reflection element (IRE), model hydrophilic surfaces were made by plasma cleaning the IRE and model hydrophobic surfaces were made by precoating the IRE with a thin film of polystyrene. Gas chromatography (GC)-IR data collection software was used to monitor adsorption kinetics during the first five minutes after injection of the enzyme into the CIRcle cell. It was found that for both lysozyme and BPN', most of the enzyme that was going to adsorb onto the model surface did so within ten seconds after injection. Nearly an order-of-magnitude more BPN' adsorbed on the hydrophobic Ge surface than the hydrophilic one, while lysozyme adsorbed somewhat more strongly to the hydrophilic Ge surface. Overnight, the lysozyme layer continued to increase in thickness, while BPN' maintained its initial coverage. The appearance of carboxylate bands in some of the adsorbed BPN' spectra suggests the occurrence of peptide bond hydrolysis. A Au/Pd coating on the CIRcle cell o-rings had a significant effect on the adsorption of BPN'. (This coating was applied in an attempt to eliminate interfering Teflon absorption bands.) An apparent electrochemical reaction occurred, involving BPN', Ge, Au/Pd, and the salt solution used to stabilize BPN'. The result of this reaction was enhanced adsorption of the enzyme around the coated o-rings, etching of the Ge IRE at the o-ring site, and some autolysis of the enzyme. No such reaction was observed with lysozyme.

  15. Soliton surfaces associated with sigma models: differential and algebraic aspects

    International Nuclear Information System (INIS)

    Goldstein, P P; Grundland, A M; Post, S

    2012-01-01

    In this paper, we consider both differential and algebraic properties of surfaces associated with sigma models. It is shown that surfaces defined by the generalized Weierstrass formula for immersion for solutions of the CP N-1 sigma model with finite action, defined in the Riemann sphere, are themselves solutions of the Euler–Lagrange equations for sigma models. On the other hand, we show that the Euler–Lagrange equations for surfaces immersed in the Lie algebra su(N), with conformal coordinates, that are extremals of the area functional, subject to a fixed polynomial identity, are exactly the Euler–Lagrange equations for sigma models. In addition to these differential constraints, the algebraic constraints, in the form of eigenvalues of the immersion functions, are systematically treated. The spectrum of the immersion functions, for different dimensions of the model, as well as its symmetry properties and its transformation under the action of the ladder operators are discussed. Another approach to the dynamics is given, i.e. description in terms of the unitary matrix which diagonalizes both the immersion functions and the projectors constituting the model. (paper)

  16. Soil Structure - A Neglected Component of Land-Surface Models

    Science.gov (United States)

    Fatichi, S.; Or, D.; Walko, R. L.; Vereecken, H.; Kollet, S. J.; Young, M.; Ghezzehei, T. A.; Hengl, T.; Agam, N.; Avissar, R.

    2017-12-01

    Soil structure is largely absent in most standard sampling and measurements and in the subsequent parameterization of soil hydraulic properties deduced from soil maps and used in Earth System Models. The apparent omission propagates into the pedotransfer functions that deduce parameters of soil hydraulic properties primarily from soil textural information. Such simple parameterization is an essential ingredient in the practical application of any land surface model. Despite the critical role of soil structure (biopores formed by decaying roots, aggregates, etc.) in defining soil hydraulic functions, only a few studies have attempted to incorporate soil structure into models. They mostly looked at the effects on preferential flow and solute transport pathways at the soil profile scale; yet, the role of soil structure in mediating large-scale fluxes remains understudied. Here, we focus on rectifying this gap and demonstrating potential impacts on surface and subsurface fluxes and system wide eco-hydrologic responses. The study proposes a systematic way for correcting the soil water retention and hydraulic conductivity functions—accounting for soil-structure—with major implications for near saturated hydraulic conductivity. Modification to the basic soil hydraulic parameterization is assumed as a function of biological activity summarized by Gross Primary Production. A land-surface model with dynamic vegetation is used to carry out numerical simulations with and without the role of soil-structure for 20 locations characterized by different climates and biomes across the globe. Including soil structure affects considerably the partition between infiltration and runoff and consequently leakage at the base of the soil profile (recharge). In several locations characterized by wet climates, a few hundreds of mm per year of surface runoff become deep-recharge accounting for soil-structure. Changes in energy fluxes, total evapotranspiration and vegetation productivity

  17. Source Surface Models and Their Impact on Solar Wind Research

    Science.gov (United States)

    Sokolov, I. V.; Roussev, I. I.; Gombosi, T. I.; Liu, Y.

    2005-05-01

    To perform realistic modeling of the important processes in the solar corona, such as coronal mass ejections, flares, as well as the acceleration of solar particles, one needs to incorporate into the physical models any complicated pattern of the coronal magnetic field. The coronal magnetic field topology is determined by the helmet streamers (with closed field lines), the coronal holes (with open field lines) as well as the fine, but crucially important, details of the small-scale active regions. The standard practice to recover the global 3-D structure of the solar magnetic field from observations is to use the source surface model, in which the field is assumed to be potential, i.e., current-free. This approach ignores any volumetric current there may be present in the corona, and also neglects the existence of the equatorial current sheet, which starts from a height of 3-5 Rs above the solar surface. The fully potential solar magnetic field would have only closed field lines, not allowing for the solar wind to exist. In our Solar Corona model, incorparated into the Space Weather Modelling Framework, the solar magnetic field is split into two constituitive parts: one potential part which is recovered from the magnetic field data (e.g., from WSO, MWO, or MDI data) using the source surface method; and, one other non-potential part. For the potential field, we keep only the spherical harmonics decreasing with distance from the Sun or, equivalently, we use a very large value of the source surface radius. For the non-potential field, we solve the time-dependent induction equation with zero boundary condition at the solar surface. The full set of conservation laws for the MHD system is solved numerically using the BATS-R-US code. To power the solar wind in our model, we use a phenomenological turbulence model described in an earlier paper. The resulting steady-state MHD solution includes the well-resolved current sheet and helmet streamers. The modeled structure of

  18. A Radiographic Measurement of the Anterior Epidural Space at L4-5 Disc Level.

    Science.gov (United States)

    Xu, Rui-Sheng; Wu, Jie-Shi; Lu, Hai-Dan; Zhu, Hao-Gang; Li, Xia; Dong, Jian; Yuan, Feng-Lai

    2017-05-01

    To observe the morphology character of the anterior epidural space at the L 4-5 disc level and to provide an anatomical basis for safely and accurately performing a percutaneous endoscopic lumbar discectomy (PELD). Fifty-five cases with L 5 S 1 lumbar disc herniation were included in this study, and cases with L 4-5 disease were excluded. When the puncture needle reached the epidural space at the L 5 S 1 level, iohexol was injected at the pressure of 50 cm H 2 O during the PELD, then C-Arm fluoroscopy was used to obtain standard lumbar frontal and lateral images. The widths of epidural space at the level of the L 4 lower endplate, the L 5 upper endplate, as well as the middle point of the L 4-5 disc were measured from the lumbar lateral X-ray film. Epidural space at the L 4-5 disc plane performs like a trapezium chart with a short side at the head end and a long side at the tail end in the lumbar lateral X-ray radiograph, while the average widths of epidural space were 10.2 ± 2.5, 12.3 ± 2.3, and 13.8 ± 2.6 mm at the upper, middle, and lower level of the L 4-5 disc. Understanding the morphological characteristics of epidural space will contribute to improving the safety of the tranforaminal percutaneous endoscopy technique. © 2017 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

  19. Spatial aggregation of land surface characteristics : impact of resolution of remote sensing data on land surface modelling

    NARCIS (Netherlands)

    Pelgrum, H.

    2000-01-01

    Land surface models describe the exchange of heat, moisture and momentum between the land surface and the atmosphere. These models can be solved regionally using remote sensing measurements as input. Input variables which can be derived from remote sensing measurements are surface albedo,

  20. Multipoint contact modeling of nanoparticle manipulation on rough surface

    Energy Technology Data Exchange (ETDEWEB)

    Zakeri, M., E-mail: m.zakeri@tabrizu.ac.ir; Faraji, J.; Kharazmi, M. [University of Tabriz, School of Engineering Emerging Technologies (Iran, Islamic Republic of)

    2016-12-15

    In this paper, the atomic force microscopy (AFM)-based 2-D pushing of nano/microparticles investigated on rough substrate by assuming a multipoint contact model. First, a new contact model was extracted and presented based on the geometrical profiles of Rumpf, Rabinovich and George models and the contact mechanics theories of JKR and Schwartz, to model the adhesion forces and the deformations in the multipoint contact of rough surfaces. The geometry of a rough surface was defined by two main parameters of asperity height (size of roughness) and asperity wavelength (compactness of asperities distribution). Then, the dynamic behaviors of nano/microparticles with radiuses in range of 50–500 nm studied during their pushing on rough substrate with a hexagonal or square arrangement of asperities. Dynamic behavior of particles were simulated and compared by assuming multipoint and single-point contact schemes. The simulation results show that the assumption of multipoint contact has a considerable influence on determining the critical manipulation force. Additionally, the assumption of smooth surfaces or single-point contact leads to large error in the obtained results. According to the results of previous research, it anticipated that a particles with the radius less than about 550 nm start to slide on smooth substrate; but by using multipoint contact model, the predicted behavior changed, and particles with radii of smaller than 400 nm begin to slide on rough substrate for different height of asperities, at first.

  1. Evaluation of the WAMME model surface fluxes using results from the AMMA land-surface model intercomparison project

    Energy Technology Data Exchange (ETDEWEB)

    Boone, Aaron Anthony [GAME-CNRM, Meteo-France, Toulouse (France); Poccard-Leclercq, Isabelle [Universite de Nantes, LETG-Geolittomer, Nantes (France); Xue, Yongkang; Feng, Jinming [University of California at Los Angeles, Los Angeles, CA (United States); Rosnay, Patricia de [European Centre for Medium Range Weather Forecasting, Reading (United Kingdom)

    2010-07-15

    The West African monsoon (WAM) circulation and intensity have been shown to be influenced by the land surface in numerous numerical studies using regional scale and global scale atmospheric climate models (RCMs and GCMs, respectively) over the last several decades. The atmosphere-land surface interactions are modulated by the magnitude of the north-south gradient of the low level moist static energy, which is highly correlated with the steep latitudinal gradients of the vegetation characteristics and coverage, land use, and soil properties over this zone. The African Multidisciplinary Monsoon Analysis (AMMA) has organised comprehensive activities in data collection and modelling to further investigate the significance land-atmosphere feedbacks. Surface energy fluxes simulated by an ensemble of land surface models from AMMA Land-surface Model Intercomparison Project (ALMIP) have been used as a proxy for the best estimate of the ''real world'' values in order to evaluate GCM and RCM simulations under the auspices of the West African Monsoon Modelling Experiment (WAMME) project, since such large-scale observations do not exist. The ALMIP models have been forced in off-line mode using forcing based on a mixture of satellite, observational, and numerical weather prediction data. The ALMIP models were found to agree well over the region where land-atmosphere coupling is deemed to be most important (notably the Sahel), with a high signal to noise ratio (generally from 0.7 to 0.9) in the ensemble and a inter-model coefficient of variation between 5 and 15%. Most of the WAMME models simulated spatially averaged net radiation values over West Africa which were consistent with the ALMIP estimates, however, the partitioning of this energy between sensible and latent heat fluxes was significantly different: WAMME models tended to simulate larger (by nearly a factor of two) monthly latent heat fluxes than ALMIP. This results due to a positive precipitation

  2. Models of the solvent-accessible surface of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.E.

    1996-09-01

    Many biopolymers such as proteins, DNA, and RNA have been studied because they have important biomedical roles and may be good targets for therapeutic action in treating diseases. This report describes how plastic models of the solvent-accessible surface of biopolymers were made. Computer files containing sets of triangles were calculated, then used on a stereolithography machine to make the models. Small (2 in.) models were made to test whether the computer calculations were done correctly. Also, files of the type (.stl) required by any ISO 9001 rapid prototyping machine were written onto a CD-ROM for distribution to American companies.

  3. 26 CFR 1.167(l)-4 - Public utility property; election to use asset depreciation range system.

    Science.gov (United States)

    2010-04-01

    ... depreciation range system. 1.167(l)-4 Section 1.167(l)-4 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT... Individuals and Corporations § 1.167(l)-4 Public utility property; election to use asset depreciation range system. (a) Application of section 167(l) to certain property subject to asset depreciation range system...

  4. Numerical modelling of surface hydrology and near-surface hydrogeology at Forsmark. Site descriptive modelling SDM. Site Forsmark

    International Nuclear Information System (INIS)

    Bosson, Emma; Gustafsson, Lars-Goeran; Sassner, Mona

    2008-09-01

    SKB is currently performing site investigations at two potential sites for a final repository for spent nuclear fuel. This report presents results of water flow and solute transport modelling of the Forsmark site. The modelling reported in this document focused on the near-surface groundwater, i.e. groundwater in Quaternary deposits and shallow rock, and surface water systems, and was performed using the MIKE SHE tool. The most recent site data used in the modelling were delivered in the Forsmark 2.3 dataset, which had its 'data freeze' on March 31, 2007. The present modelling is performed in support of the final version of the Forsmark site description that is produced during the site investigation phase. In this work, the hydrological modelling system MIKE SHE has been used to describe near-surface groundwater flow and the contact between groundwater and surface water at the Forsmark site. The surface water system at Forsmark is described with the one-dimensional 'channel flow' modelling tool MIKE 11, which is fully and dynamically integrated with MIKE SHE. The MIKE SHE model was updated with data from the F2.3 data freeze. The main updates concerned the geological description of the saturated zone and the time series data on water levels and surface water discharges. The time series data used as input data and for calibration and validation was extended until the Forsmark 2.3 data freeze (March 31, 2007). The present work can be subdivided into the following four parts: 1. Update of the numerical flow model. 2. Sensitivity analysis and calibration of the model parameters. 3. Validation of the calibrated model, followed by evaluation and identification of discrepancies between measurements and model results. 4. Additional sensitivity analysis and calibration in order to resolve the problems identified in point three above. The main actions taken during the calibration can be summarised as follows: 1. The potential evapotranspiration was reduced in order to reach

  5. Modeling of laser damage initiated by surface contamination

    International Nuclear Information System (INIS)

    Feit, M.D.; Rubenchik, A.M.; Faux, D.R.; Riddle, R.A.; Shapiro, A.; Eder, D.C.; Penetrante, B.M.; Milam, D.; Genin, F.Y.; Kozlowski, M.R.

    1996-11-01

    The authors are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, 'splashing' of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations

  6. Surface Complexation Modelling in Metal-Mineral-Bacteria Systems

    Science.gov (United States)

    Johnson, K. J.; Fein, J. B.

    2002-12-01

    The reactive surfaces of bacteria and minerals can determine the fate, transport, and bioavailability of aqueous heavy metal cations. Geochemical models are instrumental in accurately accounting for the partitioning of the metals between mineral surfaces and bacteria cell walls. Previous research has shown that surface complexation modelling (SCM) is accurate in two-component systems (metal:mineral and metal:bacteria); however, the ability of SCMs to account for metal distribution in mixed metal-mineral-bacteria systems has not been tested. In this study, we measure aqueous Cd distributions in water-bacteria-mineral systems, and compare these observations with predicted distributions based on a surface complexation modelling approach. We measured Cd adsorption in 2- and 3-component batch adsorption experiments. In the 2-component experiments, we measured the extent of adsorption of 10 ppm aqueous Cd onto either a bacterial or hydrous ferric oxide sorbent. The metal:bacteria experiments contained 1 g/L (wet wt.) of B. subtilis, and were conducted as a function of pH; the metal:mineral experiments were conducted as a function of both pH and HFO content. Two types of 3-component Cd adsorption experiments were also conducted in which both mineral powder and bacteria were present as sorbents: 1) one in which the HFO was physically but not chemically isolated from the system using sealed dialysis tubing, and 2) others where the HFO, Cd and B. subtilis were all in physical contact. The dialysis tubing approach enabled the direct determination of the concentration of Cd on each sorbing surface, after separation and acidification of each sorbent. The experiments indicate that both bacteria and mineral surfaces can dominate adsorption in the system, depending on pH and bacteria:mineral ratio. The stability constants, determined using the data from the 2-component systems, along with those for other surface and aqueous species in the systems, were used with FITEQL to

  7. ELECTRON AVALANCHE MODEL OF DIELECTRIC-VACUUM SURFACE BREAKDOWN

    Energy Technology Data Exchange (ETDEWEB)

    Lauer, E J

    2007-02-21

    The model assumes that an 'initiating event' results in positive ions on the surface near the anode and reverses the direction of the normal component of electric field so that electrons in vacuum are attracted to the dielectric locally. A sequence of surface electron avalanches progresses in steps from the anode to the cathode. For 200 kV across 1 cm, the spacing of avalanches is predicted to be about 13 microns. The time for avalanches to step from the anode to the cathode is predicted to be about a ns.

  8. Advances in land modeling of KIAPS based on the Noah Land Surface Model

    Science.gov (United States)

    Koo, Myung-Seo; Baek, Sunghye; Seol, Kyung-Hee; Cho, Kyoungmi

    2017-08-01

    As of 2013, the Noah Land Surface Model (LSM) version 2.7.1 was implemented in a new global model being developed at the Korea Institute of Atmospheric Prediction Systems (KIAPS). This land surface scheme is further refined in two aspects, by adding new physical processes and by updating surface input parameters. Thus, the treatment of glacier land, sea ice, and snow cover are addressed more realistically. Inconsistencies in the amount of absorbed solar flux at ground level by the land surface and radiative processes are rectified. In addition, new parameters are available by using 1-km land cover data, which had usually not been possible at a global scale. Land surface albedo/emissivity climatology is newly created using Moderate-Resolution Imaging Spectroradiometer (MODIS) satellitebased data and adjusted parameterization. These updates have been applied to the KIAPS-developed model and generally provide a positive impact on near-surface weather forecasting.

  9. Surface wind mixing in the Regional Ocean Modeling System (ROMS)

    Science.gov (United States)

    Robertson, Robin; Hartlipp, Paul

    2017-12-01

    Mixing at the ocean surface is key for atmosphere-ocean interactions and the distribution of heat, energy, and gases in the upper ocean. Winds are the primary force for surface mixing. To properly simulate upper ocean dynamics and the flux of these quantities within the upper ocean, models must reproduce mixing in the upper ocean. To evaluate the performance of the Regional Ocean Modeling System (ROMS) in replicating the surface mixing, the results of four different vertical mixing parameterizations were compared against observations, using the surface mixed layer depth, the temperature fields, and observed diffusivities for comparisons. The vertical mixing parameterizations investigated were Mellor- Yamada 2.5 level turbulent closure (MY), Large- McWilliams- Doney Kpp (LMD), Nakanishi- Niino (NN), and the generic length scale (GLS) schemes. This was done for one temperate site in deep water in the Eastern Pacific and three shallow water sites in the Baltic Sea. The model reproduced the surface mixed layer depth reasonably well for all sites; however, the temperature fields were reproduced well for the deep site, but not for the shallow Baltic Sea sites. In the Baltic Sea, the models overmixed the water column after a few days. Vertical temperature diffusivities were higher than those observed and did not show the temporal fluctuations present in the observations. The best performance was by NN and MY; however, MY became unstable in two of the shallow simulations with high winds. The performance of GLS nearly as good as NN and MY. LMD had the poorest performance as it generated temperature diffusivities that were too high and induced too much mixing. Further observational comparisons are needed to evaluate the effects of different stratification and wind conditions and the limitations on the vertical mixing parameterizations.

  10. Thermodynamic Modeling of Surface Tension of Aqueous Electrolyte Solution by Competitive Adsorption Model

    Directory of Open Access Journals (Sweden)

    Mohamad Javad Kamali

    2015-01-01

    Full Text Available Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption, and ENRTL activity coefficient model, the surface tension of electrolyte solutions is calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperatures in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.

  11. Modeling of dust emission for a crusted surface

    Science.gov (United States)

    Ghodsi Zadeh, Z.; Klose, M.; DuBois, D. W.

    2017-12-01

    Dust storms are frequent phenomena in the southwestern United Sates. Dust source areas in the region are often (partly) crusted. A critical prerequisite in dust aerosol modeling is an accurate representation of dust emission. While several dust emission schemes have been developed over the last decades, their applicability for crusted surfaces is not well tested. In this study, we use and test the applicability of the dust emission scheme of Shao (2004) (S04), which estimates dust emission based on the soil volume removed by saltation particle impacts, to model dust emission from a crusted surface in New Mexico, USA, for three dust events in spring 2016. Detailed field data are available for these events which are used as scheme input (surface crust and vegetation fraction, friction velocity, minimally- and fully-dispersed particle-size distributions) and for evaluation (saltation flux and dust emission flux). Results show that the saltation flux modeled with the scheme of White (1979) was overestimated by three orders of magnitude. This is expected as the supply of particles available for saltation is limited at the site. As our focus is on dust emission, a constant scaling factor was applied to match modeled and observed saltation fluxes. Parameters that describe the efficiency of saltator impacts to emit dust and the degree of dispersion during erosion need to be adapted in the S04 scheme to represent the soil surface setting at the study site. Our results show that changing those parameters has little effect on the modeled dust emission and dust emission is generally underestimated when PSDs of the top 1 cm soil layer are used as it is common. The reason for this is that the crust at the site is relatively thin and the soil overall sandy, which results in only a small difference between the two PSDs. If, however, the minimally- and fully-dispersed PSDs are replaced with the PSDs of, respectively, loose erodible material and crust, then the difference increases

  12. Surface and Flow Field Measurements on the FAITH Hill Model

    Science.gov (United States)

    Bell, James H.; Heineck, James T.; Zilliac, Gregory; Mehta, Rabindra D.; Long, Kurtis R.

    2012-01-01

    A series of experimental tests, using both qualitative and quantitative techniques, were conducted to characterize both surface and off-surface flow characteristics of an axisymmetric, modified-cosine-shaped, wall-mounted hill named "FAITH" (Fundamental Aero Investigates The Hill). Two separate models were employed: a 6" high, 18" base diameter machined aluminum model that was used for wind tunnel tests and a smaller scale (2" high, 6" base diameter) sintered nylon version that was used in the water channel facility. Wind tunnel and water channel tests were conducted at mean test section speeds of 165 fps (Reynolds Number based on height = 500,000) and 0.1 fps (Reynolds Number of 1000), respectively. The ratio of model height to boundary later height was approximately 3 for both tests. Qualitative techniques that were employed to characterize the complex flow included surface oil flow visualization for the wind tunnel tests, and dye injection for the water channel tests. Quantitative techniques that were employed to characterize the flow included Cobra Probe to determine point-wise steady and unsteady 3D velocities, Particle Image Velocimetry (PIV) to determine 3D velocities and turbulence statistics along specified planes, Pressure Sensitive Paint (PSP) to determine mean surface pressures, and Fringe Imaging Skin Friction (FISF) to determine surface skin friction (magnitude and direction). This initial report summarizes the experimental set-up, techniques used, data acquired and describes some details of the dataset that is being constructed for use by other researchers, especially the CFD community. Subsequent reports will discuss the data and their interpretation in more detail

  13. Biallelic expression of Tssc4, Nap1l4, Phlda2 and Osbpl5 in adult ...

    Indian Academy of Sciences (India)

    , kidney, skeletal muscle and subcutaneous fat using polymorphism-based sequencing approach. It was found that all the four genes showed biallelic expression in tissues in which transcripts were detected. Nap1l4 and Tssc4 were detected in ...

  14. GE~L ~4J SIR HE~R Y TI~SO~ LUKI~

    African Journals Online (AJOL)

    GE~L ~4J SIR HE~R Y TI~SO~ LUKI~. Herkoms en Jeugjare. Fulham is 'n voorstad van Londen. Oit is daar waar Henry Timson Lukin op 24 Mei 1860 as die oudste en enigste seun van Robert Henry. Lukin gebore is. Alhoewel 'n gekwalifiseerde advokaat wat daarby talle oorsese ekspedisies onderneem het, het Robert ...

  15. Influence of laser power on the deposition Ti64l4V/W composite

    CSIR Research Space (South Africa)

    Ndou, N

    2016-10-01

    Full Text Available The influence of laser power on the deposited of Ti64l4V/W composites was investigated. The energy flow rates were varied while every single other parameter were kept at a steady. The evolving microstructure and the hardness of the composites were...

  16. Cytotoxicity of poly(96L/4D-lactide) : the influence of degradation and sterilization

    NARCIS (Netherlands)

    Cordewener, FW; Joziasse, CAP; Schmitz, JP; Bos, RRM; Rozema, FR; Pennings, AJ

    2000-01-01

    The cytotoxicity of poly(96L/4D-lactide) (PLA96), and of its accumulated degradation products, was investigated following different sterilization methods and pre-determined heat-accelerated degradation intervals. PLA96 samples sterilized by either steam, ethylene oxide, or gamma irradiation were

  17. Modeling marine surface microplastic transport to assess optimal removal locations

    International Nuclear Information System (INIS)

    Sherman, Peter; Van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres. (letter)

  18. Constraining Agricultural Irrigation Surface Energy Budget Feedbacks in Atmospheric Models

    Science.gov (United States)

    Aufforth, M. E.; Desai, A. R.; Suyker, A.

    2017-12-01

    The expansion and modernization of irrigation increased the relevance of knowing the effects it has on regional weather and climate feedbacks. We conducted a set of observationally-constrained simulations determining the result irrigation exhibits on the surface energy budget, the atmospheric boundary layer, and regional precipitation feedbacks. Eddy covariance flux tower observations were analyzed from two irrigated and one rain-fed corn/soybean rotation sites located near Mead, Nebraska. The evaluated time period covered the summer growing months of June, July, and August (JJA) during the years when corn grew at all three sites. As a product of higher continuous surface moisture availability, the irrigated crops had significantly higher amounts of energy partitioned towards latent heating than the non-irrigated site. The daily average peak of latent heating at the rain-fed site occurred before the irrigated sites and was approximately 45 W/m2 lower. Land surface models were evaluated on their ability to reproduce these effects, including those used in numerical weather prediction and those used in agricultural carbon cycle projection. Model structure, mechanisms, and parameters that best represent irrigation-surface energy impacts will be compared and discussed.

  19. Modeling marine surface microplastic transport to assess optimal removal locations

    Science.gov (United States)

    Sherman, Peter; van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres.

  20. Interactive system for quick modeling of aircraft surfaces

    Science.gov (United States)

    Mudur, S. P.; Khandekar, Dilip R.

    1990-08-01

    The precise specification of surface geometry of an aircraft is one of the most important and major activities inits design. An initial design, defined by the fundamental requirements, is iteratively analysed and modified till a satisfactory configuration is obtained. Very often in the early stages the need to rapidly make modifications to the geometry for immediate analysis overrides the stringency of smoothness and correctness ofthe surfaces. This paper describes the design of an interactive system which enables the designer to quickly specify the surface geometry and to modify it easily and rapidly. In particular, the software engineering aspects are emphasized. The system uses B-splines for the representation of complex geometry. Surfaces of revolution, required to model certain parts ofthe aircraft, and other simple geometric primitives are also supported. Apart from the usual modeller facilities, features such as camber, twist and form constraints such as tangent or curvature control at a point, etc., are also provided. The system enables easy input and rapid editing of geomeiry through the use of a number of innovative concepts which aim at simplifying and speeding up the man-machine interaction. Multiple window display of entities, augmented by plots of curvature, cross sections etc. provide the visualization tool necessary to assist the designer in decision making.

  1. Can atom-surface potential measurements test atomic structure models?

    Science.gov (United States)

    Lonij, Vincent P A; Klauss, Catherine E; Holmgren, William F; Cronin, Alexander D

    2011-06-30

    van der Waals (vdW) atom-surface potentials can be excellent benchmarks for atomic structure calculations. This is especially true if measurements are made with two different types of atoms interacting with the same surface sample. Here we show theoretically how ratios of vdW potential strengths (e.g., C₃(K)/C₃(Na)) depend sensitively on the properties of each atom, yet these ratios are relatively insensitive to properties of the surface. We discuss how C₃ ratios depend on atomic core electrons by using a two-oscillator model to represent the contribution from atomic valence electrons and core electrons separately. We explain why certain pairs of atoms are preferable to study for future experimental tests of atomic structure calculations. A well chosen pair of atoms (e.g., K and Na) will have a C₃ ratio that is insensitive to the permittivity of the surface, whereas a poorly chosen pair (e.g., K and He) will have a ratio of C₃ values that depends more strongly on the permittivity of the surface.

  2. Nanoimprint Lithography on curved surfaces prepared by fused deposition modelling

    International Nuclear Information System (INIS)

    Köpplmayr, Thomas; Häusler, Lukas; Bergmair, Iris; Mühlberger, Michael

    2015-01-01

    Fused deposition modelling (FDM) is an additive manufacturing technology commonly used for modelling, prototyping and production applications. The achievable surface roughness is one of its most limiting aspects. It is however of great interest to create well-defined (nanosized) patterns on the surface for functional applications such as optical effects, electronics or bio-medical devices. We used UV-curable polymers of different viscosities and flexible stamps made of poly(dimethylsiloxane) (PDMS) to perform Nanoimprint Lithography (NIL) on FDM-printed curved parts. Substrates with different roughness and curvature were prepared using a commercially available 3D printer. The nanoimprint results were characterized by optical light microscopy, profilometry and atomic force microscopy (AFM). Our experiments show promising results in creating well-defined microstructures on the 3D-printed parts. (paper)

  3. Modeling Turbulence Generation in the Atmospheric Surface and Boundary Layers

    Science.gov (United States)

    2015-10-01

    ZT ). The initial acceleration of the rising buoyant air will be a = g∆T/TA. This is simply Archimedes ’ principle applied to the buoyant air. The... applications . 1 Various rules are employed to model C2n in the surface layer, but a key question is how to extend this estimation technique into the lower...in terms of wind turbulence the structure of the fluctuations produces a Reynolds stress tensor whose principle axes are not equal, meaning that at the

  4. Using advanced surface complexation models for modelling soil chemistry under forests: Solling forest, Germany

    International Nuclear Information System (INIS)

    Bonten, Luc T.C.; Groenenberg, Jan E.; Meesenburg, Henning; Vries, Wim de

    2011-01-01

    Various dynamic soil chemistry models have been developed to gain insight into impacts of atmospheric deposition of sulphur, nitrogen and other elements on soil and soil solution chemistry. Sorption parameters for anions and cations are generally calibrated for each site, which hampers extrapolation in space and time. On the other hand, recently developed surface complexation models (SCMs) have been successful in predicting ion sorption for static systems using generic parameter sets. This study reports the inclusion of an assemblage of these SCMs in the dynamic soil chemistry model SMARTml and applies this model to a spruce forest site in Solling Germany. Parameters for SCMs were taken from generic datasets and not calibrated. Nevertheless, modelling results for major elements matched observations well. Further, trace metals were included in the model, also using the existing framework of SCMs. The model predicted sorption for most trace elements well. - Highlights: → Surface complexation models can be well applied in field studies. → Soil chemistry under a forest site is adequately modelled using generic parameters. → The model is easily extended with extra elements within the existing framework. → Surface complexation models can show the linkages between major soil chemistry and trace element behaviour. - Surface complexation models with generic parameters make calibration of sorption superfluous in dynamic modelling of deposition impacts on soil chemistry under nature areas.

  5. Corrected electrostatic model for dipoles adsorbed on a metal surface

    Energy Technology Data Exchange (ETDEWEB)

    Maschhoff, B.L.; Cowin, J.P. (Enviornmental and Molecular Science Laboratory, Pacific Northwest Laboratories Box 999 MS K2-14, Richland, Washington 99352 (United States))

    1994-11-01

    We present a dipole--dipole interaction model for polar molecules vertically adsorbed on a idealized metal surface in an approximate analytic form suitable for estimating the coverage dependence of the work function, binding energies, and thermal desorption activation energies. In contrast to previous treatments, we have included all contributions to the interaction energy within the dipole model, such as the internal polarization energy and the coverage dependence of the self-image interaction with the metal. We show that these can contribute significantly to the total interaction energy. We present formulae for both point and extended dipole cases.

  6. Kinetic computer modeling of microwave surface-wave plasma production

    International Nuclear Information System (INIS)

    Ganachev, Ivan P.

    2004-01-01

    Kinetic computer plasma modeling occupies an intermediate position between the time consuming rigorous particle dynamic simulation and the fast but rather rough cold- or warm-plasma fluid models. The present paper reviews the kinetic modeling of microwave surface-wave discharges with accent on recent kinetic self-consistent models, where the external input parameters are reduced to the necessary minimum (frequency and intensity of the applied microwave field and pressure and geometry of the discharge vessel). The presentation is limited to low pressures, so that Boltzmann equation is solved in non-local approximation and collisional electron heating is neglected. The numerical results reproduce correctly the bi-Maxwellian electron energy distribution functions observed experimentally. (author)

  7. A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

    Science.gov (United States)

    Legleiter, Carl; Mobley, Curtis D.; Overstreet, Brandon

    2017-01-01

    This paper introduces a framework for examining connections between the flow field, the texture of the air-water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform-based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface-reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

  8. A framework for modeling connections between hydraulics, water surface roughness, and surface reflectance in open channel flows

    Science.gov (United States)

    Legleiter, Carl J.; Mobley, Curtis D.; Overstreet, Brandon T.

    2017-09-01

    This paper introduces a framework for examining connections between the flow field, the texture of the air-water interface, and the reflectance of the water surface and thus evaluating the potential to infer hydraulic information from remotely sensed observations of surface reflectance. We used a spatial correlation model describing water surface topography to illustrate the application of our framework. Nondimensional relations between model parameters and flow intensity were established based on a prior flume study. Expressing the model in the spatial frequency domain allowed us to use an efficient Fourier transform-based algorithm for simulating water surfaces. Realizations for both flume and field settings had water surface slope distributions positively correlated with velocity and water surface roughness. However, most surface facets were gently sloped and thus unlikely to yield strong specular reflections; the model exaggerated the extent of water surface features, leading to underestimation of facet slopes. A ray tracing algorithm indicated that reflectance was greatest when solar and view zenith angles were equal and the sensor scanned toward the Sun to capture specular reflections of the solar beam. Reflected energy was concentrated in a small portion of the sky, but rougher water surfaces reflected rays into a broader range of directions. Our framework facilitates flight planning to avoid surface-reflected radiance while mapping other river attributes, or to maximize this component to exploit relationships between hydraulics and surface reflectance. This initial analysis also highlighted the need for improved models of water surface topography in natural rivers.

  9. Heterogeneous nucleation of ice on model carbon surfaces

    Science.gov (United States)

    Molinero, V.; Lupi, L.; Hudait, A.

    2014-12-01

    Carbonaceous particles account for 10% of the particulate matter in the atmosphere. The experimental investigation of heterogeneous freezing of water droplets by carbonaceous particles reveals widespread ice freezing temperatures. The origin of the soot and its oxidation and aging modulate its ice nucleation ability, however, it is not known which structural and chemical characteristics of soot account for the variability in ice nucleation efficiency. We find that atomically flat carbon surfaces promote heterogeneous nucleation of ice, while molecularly rough surfaces with the same hydrophobicity do not. We investigate a large set of graphitic surfaces of various dimensions and radii of curvature consistent with those of soot in experiments, and find that variations in nanostructures alone could account for the spread in the freezing temperatures of ice on soot in experiments. A characterization of the nanostructure of soot is needed to predict its ice nucleation efficiency. Atmospheric oxidation and aging of soot modulates its ice nucleation ability. It has been suggested that an increase in the ice nucleation ability of aged soot results from an increase in the hydrophilicity of the surfaces upon oxidation. Oxidation, however, also impacts the nanostructure of soot, making it difficult to assess the separate effects of soot nanostructure and hydrophilicity in experiments. We investigate the effect of changes in hydrophilicity of model graphitic surfaces on the freezing temperature of ice. Our results indicate that the hydrophilicity of the surface is not in general a good predictor of ice nucleation ability. We find a correlation between the ability of a surface to promote nucleation of ice and the layering of liquid water at the surface. The results of this work suggest that ordering of liquid water in contact with the surface plays an important role in the heterogeneous ice nucleation mechanism. References: L. Lupi, A. Hudait and V. Molinero, J. Am. Chem. Soc

  10. Coupled Surface and Groundwater Hydrological Modeling in a Changing Climate.

    Science.gov (United States)

    Sridhar, Venkataramana; Billah, Mirza M; Hildreth, John W

    2017-11-09

    Many current watershed modeling efforts now incorporate surface water and groundwater for managing water resources since the exchanges between groundwater and surface water need a special focus considering the changing climate. The influence of groundwater dynamics on water and energy balance components is investigated in the Snake River Basin (SRB) by coupling the Variable Infiltration Capacity (VIC) and MODFLOW models (VIC-MF) for the period of 1986 through 2042. A 4.4% increase in base flows and a 10.3% decrease in peak flows are estimated by VIC-MF compared to the VIC model in SRB. The VIC-MF model shows significant improvement in the streamflow simulation (Nash-Sutcliffe efficiency [NSE] of 0.84) at King Hill, where the VIC model could not capture the effect of spring discharge in the streamflow simulation (NSE of -0.30); however, the streamflow estimates show an overall decreasing trend. Two climate scenarios representing median and high radiative-forcings such as representative concentration pathways 4.5 and 8.5 show an average increase in the water table elevations between 2.1 and 2.6 m (6.9 and 8.5 feet) through the year 2042. The spatial patterns of these exchanges show a higher groundwater elevation of 15 m (50 feet) in the downstream area and a lower elevation of up to 3 m (10 feet) in the upstream area. Broadly, this study supports results of previous work demonstrating that integrated assessment of groundwater-surface water enables stakeholders to balance pumping, recharge and base flow needs and to manage the watersheds that are subjected to human pressures more sustainably. © 2017, National Ground Water Association.

  11. Reliable low precision simulations in land surface models

    Science.gov (United States)

    Dawson, Andrew; Düben, Peter D.; MacLeod, David A.; Palmer, Tim N.

    2017-12-01

    Weather and climate models must continue to increase in both resolution and complexity in order that forecasts become more accurate and reliable. Moving to lower numerical precision may be an essential tool for coping with the demand for ever increasing model complexity in addition to increasing computing resources. However, there have been some concerns in the weather and climate modelling community over the suitability of lower precision for climate models, particularly for representing processes that change very slowly over long time-scales. These processes are difficult to represent using low precision due to time increments being systematically rounded to zero. Idealised simulations are used to demonstrate that a model of deep soil heat diffusion that fails when run in single precision can be modified to work correctly using low precision, by splitting up the model into a small higher precision part and a low precision part. This strategy retains the computational benefits of reduced precision whilst preserving accuracy. This same technique is also applied to a full complexity land surface model, resulting in rounding errors that are significantly smaller than initial condition and parameter uncertainties. Although lower precision will present some problems for the weather and climate modelling community, many of the problems can likely be overcome using a straightforward and physically motivated application of reduced precision.

  12. Water on hydrophobic surfaces: Mechanistic modeling of hydrophobic interaction chromatography.

    Science.gov (United States)

    Wang, Gang; Hahn, Tobias; Hubbuch, Jürgen

    2016-09-23

    Mechanistic models are successfully used for protein purification process development as shown for ion-exchange column chromatography (IEX). Modeling and simulation of hydrophobic interaction chromatography (HIC) in the column mode has been seldom reported. As a combination of these two techniques is often encountered in biopharmaceutical purification steps, accurate modeling of protein adsorption in HIC is a core issue for applying holistic model-based process development, especially in the light of the Quality by Design (QbD) approach. In this work, a new mechanistic isotherm model for HIC is derived by consideration of an equilibrium between well-ordered water molecules and bulk-like ordered water molecules on the hydrophobic surfaces of protein and ligand. The model's capability of describing column chromatography experiments is demonstrated with glucose oxidase, bovine serum albumin (BSA), and lysozyme on Capto™ Phenyl (high sub) as model system. After model calibration from chromatograms of bind-and-elute experiments, results were validated with batch isotherms and prediction of further gradient elution chromatograms. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Modelling and simulation of surface morphology driven by ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Yewande, E.O.

    2006-05-02

    Non-equilibrium surfaces, at nanometer length scales, externally driven via bombardment with energetic particles are known to exhibit well ordered patterns with a variety of applications in nano-technology. These patterns emerge at time scales on the order of minutes. Continuum theory has been quite successful in giving a general picture of the processes that interplay to give the observed patterns, as well as how such competition might determine the properties of the nanostructures. However, continuum theoretical descriptions are ideal only in the asymptotic limit. The only other theoretical alternative, which happens to be more suitable for the characteristic length-and time-scales of pattern formation, is Monte Carlo simulation. In this thesis, surface morphology is studied using discrete solid-on-solid Monte Carlo models of sputtering and surface diffusion. The simulations are performed in the context of the continuum theories and experiments. In agreement with the experiments, the ripples coarsen with time and the ripple velocity exhibits a power-law behaviour with the ripple wavelength, in addition, the exponent was found to depend on the simulation temperature, which suggests future experimental studies of flux dependence. Moreover, a detailed exploration of possible topographies, for different sputtering conditions, corresponding to different materials, was performed. And different surface topographies e.g. holes, ripples, and dots, were found at oblique incidence, without sample rotation. With sample rotation no new topography was found, its only role being to destroy any inherent anisotropy in the system. (orig.)

  14. Modelling and simulation of surface morphology driven by ion bombardment

    International Nuclear Information System (INIS)

    Yewande, E.O.

    2006-01-01

    Non-equilibrium surfaces, at nanometer length scales, externally driven via bombardment with energetic particles are known to exhibit well ordered patterns with a variety of applications in nano-technology. These patterns emerge at time scales on the order of minutes. Continuum theory has been quite successful in giving a general picture of the processes that interplay to give the observed patterns, as well as how such competition might determine the properties of the nanostructures. However, continuum theoretical descriptions are ideal only in the asymptotic limit. The only other theoretical alternative, which happens to be more suitable for the characteristic length-and time-scales of pattern formation, is Monte Carlo simulation. In this thesis, surface morphology is studied using discrete solid-on-solid Monte Carlo models of sputtering and surface diffusion. The simulations are performed in the context of the continuum theories and experiments. In agreement with the experiments, the ripples coarsen with time and the ripple velocity exhibits a power-law behaviour with the ripple wavelength, in addition, the exponent was found to depend on the simulation temperature, which suggests future experimental studies of flux dependence. Moreover, a detailed exploration of possible topographies, for different sputtering conditions, corresponding to different materials, was performed. And different surface topographies e.g. holes, ripples, and dots, were found at oblique incidence, without sample rotation. With sample rotation no new topography was found, its only role being to destroy any inherent anisotropy in the system. (orig.)

  15. Slag transport models for vertical and horizontal surfaces. [SLGTR code

    Energy Technology Data Exchange (ETDEWEB)

    Chow, L S.H.; Johnson, T R

    1978-01-01

    In a coal-fired MHD system, all downstream component surfaces that are exposed to combustion gases will be covered by a solid, liquid, or solid-liquid film of slag, seed, or a mixture of the two, the specific nature of the film depending on the physical properties of the slag and seed and on local conditions. An analysis was made of a partly-liquid slag film flowing on a cooled vertical or horizontal wall of a large duct, through which passed slag-laden combustion gases. The model is applicable to the high-temperature steam generators in the downstream system of an MHD power plant and was used in calculations for a radiant-boiler concept similar to that in the 1000-MWe Gilbert-STD Baseline Plant study and also for units large enough for 230 and 8 lb/s (104.3 and 3.5 kg/s) of combustion gas. The qualitative trends of the results are similar for both vertical and horizontal surfaces. The results show the effects of the slag film, slag properties, and gas emissivity on the heat flux to the steam tubes. The slag film does not reduce the rate of heat transfer in proportion to its surface temperature, because most of the heat is radiated from the gas and particles suspended in it to the slag surface.

  16. Minimal models on Riemann surfaces: The partition functions

    International Nuclear Information System (INIS)

    Foda, O.

    1990-01-01

    The Coulomb gas representation of the A n series of c=1-6/[m(m+1)], m≥3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius) 2 of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.)

  17. Minimal models on Riemann surfaces: The partition functions

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O. (Katholieke Univ. Nijmegen (Netherlands). Inst. voor Theoretische Fysica)

    1990-06-04

    The Coulomb gas representation of the A{sub n} series of c=1-6/(m(m+1)), m{ge}3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius){sup 2} of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.).

  18. A model investigation of annual surface ultraviolet radiation in Iran

    International Nuclear Information System (INIS)

    Sabziparvar, A.-A.

    2003-01-01

    In recent years, there has been some concern regarding solar ultraviolet (UV) radiation received at the earth,s surface because of its biological hazards affecting living organisms. Although the geographical distribution of ground-based UV network is relatively good in some continents,but over Asia, the number of UV instruments are not sufficient for meteorological and biological purposes. Iran, as an Asian country, is also suffering from the lack of UV monitoring network with the exception of one ground-based UV spectrophotometer site (Brower III) at Esfahan. Using a complex radiative transfer model and various meteorological data (for 8 years) such as total column ozone, cloudiness, surface albedo, surface air pressure, relative humidity, visibility and daily total solar radiation (TSR), the geographical distribution of annual integrated biological surface UV irradiances such as UVB, erythema and cataracts are calculated. The comparison is made for cloud-free and all-sky conditions for eight selected cities distributed from the southern tip of the country (25 N-60 E) to the northern border (39 N-48 E). It is shown that the difference between the annual UV at south and north in all-sky condition is larger than the differences in cloud-free condition. The ratio of some biological UV irradiances at southern cities to the same component at northern cities shows a factor of two and more which is quite significant. The possible reasons which might cause such differences are discussed

  19. Allowing for surface preparation in stress corrosion cracking modelling

    International Nuclear Information System (INIS)

    Berge, P.; Buisine, D.; Gelpi, A.

    1997-01-01

    When a 600 alloy component is significantly deformed during installation, by welding, rolling, bending, its stress corrosion cracking in Pressurized Water Nuclear Reactor's primary coolant, is significantly changed by the initial surface treatment. Therefore, the crack initiated time may be reduced by several orders of magnitude for certain surfaces preparations. Allowing for cold working of the surface, for which modelling is proposed, depends less on the degree of cold work then on the depths of the hardened layers. Honing hardens the metal over depths of about one micron for vessel head penetrations, for example, and has little influence on subsequent behaviour after the part deforms. On the other hand, coarser turning treatment produces cold worked layers which can reach several tens of microns and can very significantly reduce the initiation time compared to fine honing. So evaluation after depths of hardening is vital on test pieces for interpreting laboratory results as well as on service components for estimating their service life. Suppression by mechanical or chemical treatment of these layers, after deformation, seems to be the most appropriate solution for reducing over-stressing connected with surface treatment carried out before deformation. (author)

  20. Design of a Three Surfaces R/C Aircraft Model

    Directory of Open Access Journals (Sweden)

    D. P. Coiro

    2002-01-01

    Full Text Available Design of a three lifting surfaces radio-controlled model has been carried out at Dipartimento di Progettazione Aeronautica (DPA by the authors in the last year. The model is intended to be a UAV prototype and is now under construction. The main goal of this small aircraft's design is to check the influence of the canard surface on the aircraft's aerodynamic characteristics and flight behavior, especially at high angles of attack. The aircraft model is also intended to be a flying platform to test sensors, measurement and acquisition systems for research purposes and a valid and low-cost teaching instrument for flight dynamics and flight maneuvering. The aircraft has been designed to fly with and without canard, and all problems relative to aircraft balance and stability have been carefully analyzed and solved. The innovative configuration and the mixed wooden-composite material structure has been obtained with very simple shapes and all the design is focused on realizing a low-cost model. A complete aerodynamic analysis of the configuration up to high angles of attack and a preliminary aircraft stability and performance prediction will be presented.

  1. Modeling land-surface/atmosphere dynamics for CHAMMP

    International Nuclear Information System (INIS)

    Gutowski, W.J. Jr.

    1993-01-01

    Project progress is described on a DOE CHAMP project to model the land-surface/atmosphere coupling in a heterogeneous environment. This work is a collaboration between scientists at Iowa State University and the University of New Hampshire. Work has proceeded in two areas: baseline model coupling and data base development for model validation. The core model elements (land model, atmosphere model) have been ported to the Principal Investigator's computing system and baseline coupling has commenced. The initial target data base is the set of observations from the FIFE field campaign, which is in the process of being acquired. For the remainder of the project period, additional data from the region surrounding the FIFE site and from other field campaigns will be acquired to determine how to best extrapolate results from the initial target region to the rest of the globe. In addition, variants of the coupled model will be used to perform experiments examining resolution requirements and coupling strategies for land-atmosphere coupling in a heterogeneous environment

  2. Modelling of the initial stage of the surface discharge development

    International Nuclear Information System (INIS)

    Gibalov, V.; Pietsch, G.

    1998-01-01

    Computer modelling of the initial stage of the surface discharge was performed by solving numerically the coupled continuity, the Poisson and Townsend ionization equations and taking into account the ionization, attachment and detachment processes. The potential distribution at the dielectric surface and at the boundaries which surround the integration region have been calculated with the charge-image method in a 3D approach. In order to eliminate numerical diffusion effects, the solution of the continuity equation was corrected using a flux correction transport routine. At the positive voltage the development of the discharge channel is determined mainly by the shape of the electrode tip. At the negative voltage the following phases of the discharge may be distinguished: the initial phase, the cathode directed streamer phase resulting in the cathode layer formation, and the propagating phase. The physical processes governing each discharge phase are described in detail. (J.U.)

  3. Operationalizing the TANIC and NICA-L3/L4 Tools to Improve Informatics Competencies.

    Science.gov (United States)

    Sipes, Carolyn; McGonigle, Dee; Hunter, Kathy; Hebda, Toni; Hill, Taryn; Lamblin, Jean

    2016-01-01

    Two tools were developed for nurses to self-assess different levels of informatics competencies. The TANIC is used for all nurses to self-assess; the NICA-L3/L4 is a tool for the informatics nurse specialist (INS) to self-assess skill levels. There are 167 informatics items in the TANIC and 178 advanced informatics items in the NICA-L3/L4. These tools were piloted; the results presented here. Based on the evaluation, the tools have been integrated into informatics courses at the BSN and MSN programs at Chamberlain College of Nursing, and presented in two AACN webinars and other national conferences. Numerous requests have been honored to provide the tools for other schools of nursing to use in their courses, including DNP programs. Other requests include those from CNIOs and managers to include in their job descriptions for informatics nurses.

  4. Modeling Surface Water Flow in the Atchafalaya Basin

    Science.gov (United States)

    Liu, K.; Simard, M.

    2017-12-01

    While most of the Mississippi River Delta is sinking due to insufficient sediment supply and subsidence, the stable wetlands and the prograding delta systems in the Atchafalaya Basin provide a unique opportunity to study the constructive interactions between riverine and marine forcings and their impacts upon coastal morphology. To better understand the hydrodynamics in this region, we developed a numerical modeling system for the water flow through the river channel - deltas - wetlands networks in the Atchafalaya Basin. Determining spatially varying model parameters for a large area composed of such diverse land cover types poses a challenge to developing an accurate numerical model. For example, the bottom friction coefficient can not be measured directly and the available elevation maps for the wetlands in the basin are inaccurate. To overcome these obstacles, we developed the modeling system in three steps. Firstly, we modeled river bathymetry based on in situ sonar transects and developed a simplified 1D model for the Wax Lake Outlet using HEC-RAS. Secondly, we used a Bayesian approach to calibrate the model automatically and infer important unknown parameters such as riverbank elevation and bottom friction coefficient through Markov Chain Monte Carlo (MCMC) simulations. We also estimated the wetland elevation based on the distribution of different vegetation species in the basin. Thirdly, with the lessons learnt from the 1D model, we developed a depth-averaged 2D model for the whole Atchafalaya Basin using Delft3D. After calibrations, the model successfully reproduced the water levels measured at five gauges in the Wax Lake Outlet and the modeled water surface profile along the channel agreed reasonably well with our LIDAR measurements. In addition, the model predicted a one-hour delay in tidal phase from the Wax Lake Delta to the upstream gauge. In summary, this project presents a procedure to initialize hydrology model parameters that integrates field

  5. Assessing modeled Greenland surface mass balance in the GISS Model E2 and its sensitivity to surface albedo

    Science.gov (United States)

    Alexander, Patrick; LeGrande, Allegra N.; Koenig, Lora S.; Tedesco, Marco; Moustafa, Samiah E.; Ivanoff, Alvaro; Fischer, Robert P.; Fettweis, Xavier

    2016-04-01

    The surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) plays an important role in global sea level change. Regional Climate Models (RCMs) such as the Modèle Atmosphérique Régionale (MAR) have been employed at high spatial resolution with relatively complex physics to simulate ice sheet SMB. Global climate models (GCMs) incorporate less sophisticated physical schemes and provide outputs at a lower spatial resolution, but have the advantage of modeling the interaction between different components of the earth's oceans, climate, and land surface at a global scale. Improving the ability of GCMs to represent ice sheet SMB is important for making predictions of future changes in global sea level. With the ultimate goal of improving SMB simulated by the Goddard Institute for Space Studies (GISS) Model E2 GCM, we compare simulated GrIS SMB against the outputs of the MAR model and radar-derived estimates of snow accumulation. In order to reproduce present-day climate variability in the Model E2 simulation, winds are constrained to match the reanalysis datasets used to force MAR at the lateral boundaries. We conduct a preliminary assessment of the sensitivity of the simulated Model E2 SMB to surface albedo, a parameter that is known to strongly influence SMB. Model E2 albedo is set to a fixed value of 0.8 over the entire ice sheet in the initial configuration of the model (control case). We adjust this fixed value in an ensemble of simulations over a range of 0.4 to 0.8 (roughly the range of observed summer GrIS albedo values) to examine the sensitivity of ice-sheet-wide SMB to albedo. We prescribe albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43A3 v6 to examine the impact of a more realistic spatial and temporal variations in albedo. An age-dependent snow albedo parameterization is applied, and its impact on SMB relative to observations and the RCM is assessed.

  6. Improvements to a Response Surface Thermal Model for Orion

    Science.gov (United States)

    Miller, Stephen W.; Walker, William Q.

    2011-01-01

    A study was performed to determine if a Design of Experiments (DOE)/Response Surface Methodology could be applied to on-orbit thermal analysis and produce a set of Response Surface Equations (RSE) that predict Orion vehicle temperatures within 10 F. The study used the Orion Outer Mold Line model. Five separate factors were identified for study: yaw, pitch, roll, beta angle, and the environmental parameters. Twenty-three external Orion components were selected and their minimum and maximum temperatures captured over a period of two orbits. Thus, there are 46 responses. A DOE case matrix of 145 runs was developed. The data from these cases were analyzed to produce a fifth order RSE for each of the temperature responses. For the 145 cases in the DOE matrix, the agreement between the engineering data and the RSE predictions was encouraging with 40 of the 46 RSEs predicting temperatures within the goal band. However, the verification cases showed most responses did not meet the 10 F goal. After reframing the focus of the study to better align the RSE development with the purposes of the model, a set of RSEs for both the minimum and maximum radiator temperatures was produced which predicted the engineering model output within +/-4 F. Therefore, with the correct application of the DOE/RSE methodology, RSEs can be developed that provide analysts a fast and easy way to screen large numbers of environments and assess proposed changes to the RSE factors.

  7. Axisymmetric Lattice Boltzmann Model of Droplet Impact on Solid Surfaces

    Science.gov (United States)

    Dalgamoni, Hussein; Yong, Xin

    2017-11-01

    Droplet impact is a ubiquitous fluid phenomena encountered in scientific and engineering applications such as ink-jet printing, coating, electronics manufacturing, and many others. It is of great technological importance to understand the detailed dynamics of drop impact on various surfaces. The lattice Boltzmann method (LBM) emerges as an efficient method for modeling complex fluid systems involving rapidly evolving fluid-fluid and fluid-solid interfaces with complex geometries. In this work, we model droplet impact on flat solid substrates with well-defined wetting behavior using a two-phase axisymmetric LBM with high density and viscosity contrasts. We extend the two-dimensional Lee and Liu model to capture axisymmetric effect in the normal impact. First we compare the 2D axisymmetric results with the 2D and 3D results reported by Lee and Liu to probe the effect of axisymmetric terms. Then, we explore the effects of Weber number, Ohnesorge number, and droplet-surface equilibrium contact angle on the impact. The dynamic contact angle and spreading factor of the droplet during impact are investigated to qualitatively characterize the impact dynamics.

  8. Coupling a groundwater model with a land surface model to improve water and energy cycle simulation

    Directory of Open Access Journals (Sweden)

    W. Tian

    2012-12-01

    Full Text Available Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB is developed based on the full coupling of a typical land surface model (SiB2 and a 3-D variably saturated groundwater model (AquiferFlow. In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reach of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.

  9. Surface complexation models for uranium adsorption in the sub-surface environment

    International Nuclear Information System (INIS)

    Payne, T.E.

    2007-01-01

    Adsorption experiments with soil component minerals under a range of conditions are being used to develop models of uranium(VI) uptake in the sub-surface environment. The results show that adsorption of U on iron oxides and clay minerals is influenced by chemical factors including the pH, partial pressure of CO 2 , and the presence of ligands such as phosphate. Surface complexation models (SCMs) can be used to simulate U adsorption on these minerals. The SCMs are based on plausible mechanistic assumptions and describe the experimental data more adequately than Kd values or sorption isotherms. It is conceptually possible to simulate U sorption data on complex natural samples by combining SCMs for individual component minerals. This approach was used to develop a SCM for U adsorption to mineral assemblages from Koongarra (Australia), and produced a reasonable description of U uptake. In order to assess the applicability of experimental data to the field situation, in-situ measurements of U distributions between solid and liquid phases were undertaken at the Koongarra U deposit. This field partitioning data showed a satisfactory agreement with laboratory sorption data obtained under comparable conditions. (author)

  10. Non-linear sigma models on arbitrary genus Riemann surfaces

    International Nuclear Information System (INIS)

    Aldazabal, G.; Diaz, A.H.; Zhang, R.B.

    1987-05-01

    A Ward-Takahashi type identity is obtained for two insertions of the energy-momentum tensor of the non-linear sigma model on an arbitrary Riemann surface. The identity shows explicitly how the Virasoro algebra is violated by spurious terms generated by the trace anomaly. Requiring these terms to vanish leads to a set of constraints on the graviton and dilaton background fields, which are necessary for the algebra to be restored. Although the modular parameters play an important role in the computation, the background field equations turn out to be genus independent up to order α'. (author). 10 refs, 2 figs

  11. Computer Modeling of Planetary Surface Temperatures in Introductory Astronomy Courses

    Science.gov (United States)

    Barker, Timothy; Goodman, J.

    2013-01-01

    Barker, T., and Goodman, J. C., Wheaton College, Norton, MA Computer modeling is an essential part of astronomical research, and so it is important that students be exposed to its powers and limitations in the first (and, perhaps, only) astronomy course they take in college. Building on the ideas of Walter Robinson (“Modeling Dynamic Systems,” Springer, 2002) we have found that STELLA software (ISEE Systems) allows introductory astronomy students to do sophisticated modeling by the end of two classes of instruction, with no previous experience in computer programming or calculus. STELLA’s graphical interface allows students to visualize systems in terms of “flows” in and out of “stocks,” avoiding the need to invoke differential equations. Linking flows and stocks allows feedback systems to be constructed. Students begin by building an easily understood system: a leaky bucket. This is a simple negative feedback system in which the volume in the bucket (a “stock”) depends on a fixed inflow rate and an outflow that increases in proportion to the volume in the bucket. Students explore how changing inflow rate and feedback parameters affect the steady-state volume and equilibration time of the system. This model is completed within a 50-minute class meeting. In the next class, students are given an analogous but more sophisticated problem: modeling a planetary surface temperature (“stock”) that depends on the “flow” of energy from the Sun, the planetary albedo, the outgoing flow of infrared radiation from the planet’s surface, and the infrared return from the atmosphere. Students then compare their STELLA model equilibrium temperatures to observed planetary temperatures, which agree with model ones for worlds without atmospheres, but give underestimates for planets with atmospheres, thus introducing students to the concept of greenhouse warming. We find that if we give the students part of this model at the start of a 50-minute class they are

  12. Model Selection and Quality Estimation of Time Series Models for Artificial Technical Surface Generation

    Directory of Open Access Journals (Sweden)

    Matthias Eifler

    2017-12-01

    Full Text Available Standard compliant parameter calculation in surface topography analysis takes the manufacturing process into account. Thus, the measurement technician can be supported with automated suggestions for preprocessing, filtering and evaluation of the measurement data based on the character of the surface topography. Artificial neuronal networks (ANN are one approach for the recognition or classification of technical surfaces. However the required set of training data for ANN is often not available, especially when data acquisition is time consuming or expensive—as e.g., measuring surface topography. Thus, generation of artificial (simulated data becomes of interest. An approach from time series analysis is chosen and examined regarding its suitability for the description of technical surfaces: the ARMAsel model, an approach for time series modelling which is capable of choosing the statistical model with the smallest prediction error and the best number of coefficients for a certain surface. With a reliable model which features the relevant stochastic properties of a surface, a generation of training data for classifiers of artificial neural networks is possible. Based on the determined ARMA-coefficients from the ARMAsel-approach, with only few measured datasets many different artificial surfaces can be generated which can be used for training classifiers of an artificial neural network. In doing so, an improved calculation of the model input data for the generation of artificial surfaces is possible as the training data generation is based on actual measurement data. The trained artificial neural network is tested with actual measurement data of surfaces that were manufactured with varying manufacturing methods and a recognition rate of the according manufacturing principle between 60% and 78% can be determined. This means that based on only few measured datasets, stochastic surface information of various manufacturing principles can be extracted

  13. A multi-surface plasticity model for ductile fracture simulations

    Science.gov (United States)

    Keralavarma, Shyam M.

    2017-06-01

    The growth and coalescence of micro-voids in a material undergoing ductile fracture depends strongly on the loading path. Void growth occurs by diffuse plasticity in the material and is sensitive to the hydrostatic stress, while void coalescence occurs by the localization of plastic deformation in the inter-void ligaments under a combination of normal and shear stresses on the localization plane. In this paper, a micromechanics-based plasticity model is developed for an isotropic porous material, accounting for both diffuse and localized modes of plasticity at the micro-scale. A multi-surface approach is adopted, and two existing plasticity models that separately account for the two modes of yielding, above, are synthesized to propose an effective isotropic yield criterion and associated state evolution equations. The yield criterion is validated by comparison with quasi-exact numerical yield loci computed using a finite elements based limit analysis procedure. It is shown that the new criterion is in better agreement with the numerical loci than the Gurson model, particularly for large values of the porosity for which the loading path dependence of the yield stress is well predicted by the new model. Even at small porosities, it is shown that the new model predicts marginally lower yield stresses under low triaxiality shear dominated loadings compared to the Gurson model, in agreement with the numerical limit analysis data. Predictions for the strains to the onset of coalescence under proportional loading, obtained by numerically integrating the model, indicate that void coalescence tends to occur at relatively small plastic strain and porosity levels under shear dominated loadings. Implications on the prediction of ductility using the new model in fracture simulations are discussed.

  14. Boussinesq modeling of surface waves due to underwater landslides

    Directory of Open Access Journals (Sweden)

    D. Dutykh

    2013-05-01

    Full Text Available Consideration is given to the influence of an underwater landslide on waves at the surface of a shallow body of fluid. The equations of motion that govern the evolution of the barycenter of the landslide mass include various dissipative effects due to bottom friction, internal energy dissipation, and viscous drag. The surface waves are studied in the Boussinesq scaling, with time-dependent bathymetry. A numerical model for the Boussinesq equations is introduced that is able to handle time-dependent bottom topography, and the equations of motion for the landslide and surface waves are solved simultaneously. The numerical solver for the Boussinesq equations can also be restricted to implement a shallow-water solver, and the shallow-water and Boussinesq configurations are compared. A particular bathymetry is chosen to illustrate the general method, and it is found that the Boussinesq system predicts larger wave run-up than the shallow-water theory in the example treated in this paper. It is also found that the finite fluid domain has a significant impact on the behavior of the wave run-up.

  15. Subjective surfaces: a geometric model for boundary completion

    Energy Technology Data Exchange (ETDEWEB)

    Sarti, Alessandro; Malladi, Ravi; Sethian, J.A.

    2000-06-01

    We present a geometric model and a computational method for segmentation of images with missing boundaries. In many situations, the human visual system fills in missing gaps in edges and boundaries, building and completing information that is not present. Boundary completion presents a considerable challenge in computer vision, since most algorithms attempt to exploit existing data. A large body of work concerns completion models, which postulate how to construct missing data; these models are often trained and specific to particular images. In this paper, we take the following, alternative perspective: we consider a reference point within an image as given, and then develop an algorithm which tries to build missing information on the basis of the given point of view and the available information as boundary data to the algorithm. Starting from this point of view, a surface is constructed. It is then evolved with the mean curvature flow in the metric induced by the image until a piecewise constant solution is reached. We test the computational model on modal completion, amodal completion, texture, photo and medical images. We extend the geometric model and the algorithm to 3D in order to extract shapes from low signal/noise ratio medical volumes. Results in 3D echocardiography and 3D fetal echography are presented.

  16. Modelling of long term nitrogen retention in surface waters

    Science.gov (United States)

    Halbfaß, S.; Gebel, M.; Bürger, S.

    2010-12-01

    In order to derive measures to reduce nutrient loadings into waters in Saxony, we calculated nitrogen inputs with the model STOFFBILANZ on the regional scale. Thereby we have to compare our modelling results to measured loadings at the river basin outlets, considering long term nutrient retention in surface waters. The most important mechanism of nitrogen retention is the denitrification in the contact zone of water and sediment, being controlled by hydraulic and micro-biological processes. Retention capacity is derived on the basis of the nutrient spiralling concept, using water residence time (hydraulic aspect) and time-specific N-uptake by microorganisms (biological aspect). Short time related processes of mobilization and immobilization are neglected, because they are of minor importance for the derivation of measures on the regional scale.

  17. Core surface flow modelling from high-resolution secular variation

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils

    2006-01-01

    -flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....

  18. Modeling global distribution of agricultural insecticides in surface waters.

    Science.gov (United States)

    Ippolito, Alessio; Kattwinkel, Mira; Rasmussen, Jes J; Schäfer, Ralf B; Fornaroli, Riccardo; Liess, Matthias

    2015-03-01

    Agricultural insecticides constitute a major driver of animal biodiversity loss in freshwater ecosystems. However, the global extent of their effects and the spatial extent of exposure remain largely unknown. We applied a spatially explicit model to estimate the potential for agricultural insecticide runoff into streams. Water bodies within 40% of the global land surface were at risk of insecticide runoff. We separated the influence of natural factors and variables under human control determining insecticide runoff. In the northern hemisphere, insecticide runoff presented a latitudinal gradient mainly driven by insecticide application rate; in the southern hemisphere, a combination of daily rainfall intensity, terrain slope, agricultural intensity and insecticide application rate determined the process. The model predicted the upper limit of observed insecticide exposure measured in water bodies (n = 82) in five different countries reasonably well. The study provides a global map of hotspots for insecticide contamination guiding future freshwater management and conservation efforts. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Convergence of surface diffusion parameters with model crystal size

    Science.gov (United States)

    Cohen, Jennifer M.; Voter, Arthur F.

    1994-07-01

    A study of the variation in the calculated quantities for adatom diffusion with respect to the size of the model crystal is presented. The reported quantities include surface diffusion barrier heights, pre-exponential factors, and dynamical correction factors. Embedded atom method (EAM) potentials were used throughout this effort. Both the layer size and the depth of the crystal were found to influence the values of the Arrhenius factors significantly. In particular, exchange type mechanisms required a significantly larger model than standard hopping mechanisms to determine adatom diffusion barriers of equivalent accuracy. The dynamical events that govern the corrections to transition state theory (TST) did not appear to be as sensitive to crystal depth. Suitable criteria for the convergence of the diffusion parameters with regard to the rate properties are illustrated.

  20. CARVE: L4 Gridded Footprints from WRF-STILT model, 2012-2016

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides Weather Research and Forecasting (WRF) Stochastic Time-Inverted Lagrangian Transport (STILT) Footprint data products for particle receptors...

  1. Bayesian estimation of regularization parameters for deformable surface models

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, G.S.; Lehovich, A.; Hanson, K.M.

    1999-02-20

    In this article the authors build on their past attempts to reconstruct a 3D, time-varying bolus of radiotracer from first-pass data obtained by the dynamic SPECT imager, FASTSPECT, built by the University of Arizona. The object imaged is a CardioWest total artificial heart. The bolus is entirely contained in one ventricle and its associated inlet and outlet tubes. The model for the radiotracer distribution at a given time is a closed surface parameterized by 482 vertices that are connected to make 960 triangles, with nonuniform intensity variations of radiotracer allowed inside the surface on a voxel-to-voxel basis. The total curvature of the surface is minimized through the use of a weighted prior in the Bayesian framework, as is the weighted norm of the gradient of the voxellated grid. MAP estimates for the vertices, interior intensity voxels and background count level are produced. The strength of the priors, or hyperparameters, are determined by maximizing the probability of the data given the hyperparameters, called the evidence. The evidence is calculated by first assuming that the posterior is approximately normal in the values of the vertices and voxels, and then by evaluating the integral of the multi-dimensional normal distribution. This integral (which requires evaluating the determinant of a covariance matrix) is computed by applying a recent algorithm from Bai et. al. that calculates the needed determinant efficiently. They demonstrate that the radiotracer is highly inhomogeneous in early time frames, as suspected in earlier reconstruction attempts that assumed a uniform intensity of radiotracer within the closed surface, and that the optimal choice of hyperparameters is substantially different for different time frames.

  2. Nuclear inelastic scattering cross sections for the transitions to L = 4 and L = 5 states in nuclei

    International Nuclear Information System (INIS)

    Nasmin Rahman, S.; Haque, Sangita; Rahman, A.Md.

    2004-07-01

    The generalized scattering amplitudes of the adiabatic distorted waves theory have been developed by Austem and Blair, connecting the inelastic scattering amplitudes in terms of the elastic scattering amplitudes. Potgieter and Frahn obtained simple, closed and explicit expressions for the inelastic scattering amplitudes, again in the adiabatic approximation, under strong absorption condition. These are analogous to the strong absorption model formulae for elastic scattering. In a previous communication, inelastic scattering cross section leading to the population of L = 2 and L = 3 states in nuclei are derived by us, using the general formulations due to Potgieter and Fahn. We derive here closed expressions for the cross sections for the inelastic scattering, transiting to L = 4 and L = 5 states in nuclei in the same line as before and satisfactory and simultaneous fits to the elastic as well as inelastic angular distributions are obtained. (author)

  3. BUILDING DETECTION USING AERIAL IMAGES AND DIGITAL SURFACE MODELS

    Directory of Open Access Journals (Sweden)

    J. Mu

    2017-05-01

    Full Text Available In this paper a method for building detection in aerial images based on variational inference of logistic regression is proposed. It consists of three steps. In order to characterize the appearances of buildings in aerial images, an effective bag-of-Words (BoW method is applied for feature extraction in the first step. In the second step, a classifier of logistic regression is learned using these local features. The logistic regression can be trained using different methods. In this paper we adopt a fully Bayesian treatment for learning the classifier, which has a number of obvious advantages over other learning methods. Due to the presence of hyper prior in the probabilistic model of logistic regression, approximate inference methods have to be applied for prediction. In order to speed up the inference, a variational inference method based on mean field instead of stochastic approximation such as Markov Chain Monte Carlo is applied. After the prediction, a probabilistic map is obtained. In the third step, a fully connected conditional random field model is formulated and the probabilistic map is used as the data term in the model. A mean field inference is utilized in order to obtain a binary building mask. A benchmark data set consisting of aerial images and digital surfaced model (DSM released by ISPRS for 2D semantic labeling is used for performance evaluation. The results demonstrate the effectiveness of the proposed method.

  4. Haptic Decorating on the Surface of Virtual Clay Model

    Directory of Open Access Journals (Sweden)

    Huang Lei

    2018-01-01

    Full Text Available A novel haptic decorating method on the surface of virtual clay model is proposed. The relationship between brush deformation and endured force is researched for the first time by applying the spring-mass model to construct the 3D brush model. Then, the collision detection between virtual hairy brush and virtual clay model is researched based on collision algorithm of weighted average distance. When the hairy brush initially collides with 3D exterior, the tactility is simulated and the interactive virtual painting on the 3D exterior is carried out practically. The 3D brush stroke is formed by superimposing 3D brush footprints along the painting direction and controlling the stress of the brush. The ink quantity in the brush footprint is determined according to the proposed positive correlation between the exerted pressure on brush and outflow ink quantity of the brush. A painting storage method is also presented for storing and displaying 3D stroke painting results. The proposed method has been successfully applied in the 3D virtual painting system based on real-time force feedback technology. With this system, the 3D brush strokes with 3D half-dry and ink diffusion results can be painted with a Phantom Desktop haptic device, which effectively enhance reality to users.

  5. Data-Model Comparison of Pliocene Sea Surface Temperature

    Science.gov (United States)

    Dowsett, H. J.; Foley, K.; Robinson, M. M.; Bloemers, J. T.

    2013-12-01

    The mid-Piacenzian (late Pliocene) climate represents the most geologically recent interval of long-term average warmth and shares similarities with the climate projected for the end of the 21st century. As such, its fossil and sedimentary record represents a natural experiment from which we can gain insight into potential climate change impacts, enabling more informed policy decisions for mitigation and adaptation. We present the first systematic comparison of Pliocene sea surface temperatures (SST) between an ensemble of eight climate model simulations produced as part of PlioMIP (Pliocene Model Intercomparison Project) and the PRISM (Pliocene Research, Interpretation and Synoptic Mapping) Project mean annual SST field. Our results highlight key regional (mid- to high latitude North Atlantic and tropics) and dynamic (upwelling) situations where there is discord between reconstructed SST and the PlioMIP simulations. These differences can lead to improved strategies for both experimental design and temporal refinement of the palaeoenvironmental reconstruction. Scatter plot of multi-model-mean anomalies (squares) and PRISM3 data anomalies (large blue circles) by latitude. Vertical bars on data anomalies represent the variability of warm climate phase within the time-slab at each locality. Small colored circles represent individual model anomalies and show the spread of model estimates about the multi-model-mean. While not directly comparable in terms of the development of the means nor the meaning of variability, this plot provides a first order comparison of the anomalies. Encircled areas are a, PRISM low latitude sites outside of upwelling areas; b, North Atlantic coastal sequences and Mediterranean sites; c, large anomaly PRISM sites from the northern hemisphere. Numbers identify Ocean Drilling Program sites.

  6. Replication of surface features from a master model to an amorphous metallic article

    Science.gov (United States)

    Johnson, William L.; Bakke, Eric; Peker, Atakan

    1999-01-01

    The surface features of an article are replicated by preparing a master model having a preselected surface feature thereon which is to be replicated, and replicating the preselected surface feature of the master model. The replication is accomplished by providing a piece of a bulk-solidifying amorphous metallic alloy, contacting the piece of the bulk-solidifying amorphous metallic alloy to the surface of the master model at an elevated replication temperature to transfer a negative copy of the preselected surface feature of the master model to the piece, and separating the piece having the negative copy of the preselected surface feature from the master model.

  7. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    International Nuclear Information System (INIS)

    Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad; Rafii-Tabar, Hashem

    2014-01-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin–Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  8. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    Science.gov (United States)

    Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad; Rafii-Tabar, Hashem

    2014-05-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin-Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  9. Reinforcement Toolbox, a Parametric Reinforcement Modelling Tool for Curved Surface Structures

    NARCIS (Netherlands)

    Lauppe, J.; Rolvink, A.; Coenders, J.L.

    2013-01-01

    This paper presents a computational strategy and parametric modelling toolbox which aim at enhancing the design- and production process of reinforcement in freeform curved surface structures. The computational strategy encompasses the necessary steps of raising an architectural curved surface model

  10. Surface system Forsmark. Site descriptive modelling SDM-Site Forsmark

    International Nuclear Information System (INIS)

    Lindborg, Tobias

    2008-12-01

    SKB has undertaken site characterization of two different areas, Forsmark and Laxemar-Simpevarp, in order to find a suitable location for a geological repository for spent nuclear fuel. This report focuses on the site descriptive modelling of the surface system at Forsmark. The characterization of the surface system at the site was primarily made by identifying and describing important properties in different parts of the surface system, properties concerning e.g. hydrology and climate, Quaternary deposits and soils, hydrochemistry, vegetation, ecosystem functions, but also current and historical land use. The report presents available input data, methodology for data evaluation and modelling, and resulting models for each of the different disciplines. Results from the modelling of the surface system are also integrated with results from modelling of the deep bedrock system. The Forsmark site is located within the municipality of Oesthammar, about 120 km north of Stockholm. The investigated area is located along the shoreline of Oeregrundsgrepen, a funnel-shaped bay of the Baltic Sea. The area is characterized by small-scale topographic variations and is almost entirely located at altitudes lower than 20 metres above sea level. The Quaternary deposits in the area are dominated by till, characterized by a rich content of calcite which was transported by the glacier ice to the area from the sedimentary bedrock of Gaevlebukten about 100 km north of Forsmark. As a result, the surface waters and shallow groundwater at Forsmark are characterized by high pH values and high concentrations of certain major constituents, especially calcium and bicarbonate. The annual precipitation and runoff are 560 and 150 mm, respectively. The lakes are small and shallow, with mean and maximum depths ranging from approximately 0.1 to 1 m and 0.4 to 2 m. Sea water flows into the most low-lying lakes during events giving rise to very high sea levels. Wetlands are frequent and cover 25 to 35

  11. Modeling adsorption and reactions of organic molecules at metal surfaces.

    Science.gov (United States)

    Liu, Wei; Tkatchenko, Alexandre; Scheffler, Matthias

    2014-11-18

    CONSPECTUS: The understanding of adsorption and reactions of (large) organic molecules at metal surfaces plays an increasingly important role in modern surface science and technology. Such hybrid inorganic/organic systems (HIOS) are relevant for many applications in catalysis, light-emitting diodes, single-molecule junctions, molecular sensors and switches, and photovoltaics. Obviously, the predictive modeling and understanding of the structure and stability of such hybrid systems is an essential prerequisite for tuning their electronic properties and functions. At present, density-functional theory (DFT) is the most promising approach to study the structure, stability, and electronic properties of complex systems, because it can be applied to both molecules and solids comprising thousands of atoms. However, state-of-the-art approximations to DFT do not provide a consistent and reliable description for HIOS, which is largely due to two issues: (i) the self-interaction of the electrons with themselves arising from the Hartree term of the total energy that is not fully compensated in approximate exchange-correlation functionals, and (ii) the lack of long-range part of the ubiquitous van der Waals (vdW) interactions. The self-interaction errors sometimes lead to incorrect description of charge transfer and electronic level alignment in HIOS, although for molecules adsorbed on metals these effects will often cancel out in total energy differences. Regarding vdW interactions, several promising vdW-inclusive DFT-based methods have been recently demonstrated to yield remarkable accuracy for intermolecular interactions in the gas phase. However, the majority of these approaches neglect the nonlocal collective electron response in the vdW energy tail, an effect that is particularly strong in condensed phases and at interfaces between different materials. Here we show that the recently developed DFT+vdW(surf) method that accurately accounts for the collective electronic

  12. Adaptive Surface Modeling of Soil Properties in Complex Landforms

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2017-06-01

    Full Text Available Abstract: Spatial discontinuity often causes poor accuracy when a single model is used for the surface modeling of soil properties in complex geomorphic areas. Here we present a method for adaptive surface modeling of combined secondary variables to improve prediction accuracy during the interpolation of soil properties (ASM-SP. Using various secondary variables and multiple base interpolation models, ASM-SP was used to interpolate soil K+ in a typical complex geomorphic area (Qinghai Lake Basin, China. Five methods, including inverse distance weighting (IDW, ordinary kriging (OK, and OK combined with different secondary variables (e.g., OK-Landuse, OK-Geology, and OK-Soil, were used to validate the proposed method. The mean error (ME, mean absolute error (MAE, root mean square error (RMSE, mean relative error (MRE, and accuracy (AC were used as evaluation indicators. Results showed that: (1 The OK interpolation result is spatially smooth and has a weak bull's-eye effect, and the IDW has a stronger ‘bull’s-eye’ effect, relatively. They both have obvious deficiencies in depicting spatial variability of soil K+. (2 The methods incorporating combinations of different secondary variables (e.g., ASM-SP, OK-Landuse, OK-Geology, and OK-Soil were associated with lower estimation bias. Compared with IDW, OK, OK-Landuse, OK-Geology, and OK-Soil, the accuracy of ASM-SP increased by 13.63%, 10.85%, 9.98%, 8.32%, and 7.66%, respectively. Furthermore, ASM-SP was more stable, with lower MEs, MAEs, RMSEs, and MREs. (3 ASM-SP presents more details than others in the abrupt boundary, which can render the result consistent with the true secondary variables. In conclusion, ASM-SP can not only consider the nonlinear relationship between secondary variables and soil properties, but can also adaptively combine the advantages of multiple models, which contributes to making the spatial interpolation of soil K+ more reasonable.

  13. Facet Model and Mathematical Morphology for Surface Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Abidi, B.R.; Goddard, J.S.; Hunt, M.A.; Sari-Sarraf, H.

    1999-11-13

    This paper describes an algorithm for the automatic segmentation and representation of surface structures and non-uniformities in an industrial setting. The automatic image processing and analysis algorithm is developed as part of a complete on-line web characterization system of a papermaking process at the wet end. The goal is to: (1) link certain types of structures on the surface of the web to known machine parameter values, and (2) find the connection between detected structures at the beginning of the line and defects seen on the final product. Images of the pulp mixture (slurry), carried by a fast moving table, are obtained using a stroboscopic light and a CCD camera. This characterization algorithm succeeded where conventional contrast and edge detection techniques failed due to a poorly controlled environment. The images obtained have poor contrast and contain noise caused by a variety of sources. After a number of enhancement steps, conventional segmentation methods still f ailed to detect any structures and are consequently discarded. Techniques tried include the Canny edge detector, the Sobel, Roberts, and Prewitt's filters, as well as zero crossings. The facet model algorithm, is then applied to the images with various parameter settings and is found to be successful in detecting the various topographic characteristics of the surface of the slurry. Pertinent topographic elements are retained and a filtered image computed. Carefully tailored morphological operators are then applied to detect and segment regions of interest. Those regions are then selected according to their size, elongation, and orientation. Their bounding rectangles are computed and represented. Also addressed in this paper are aspects of the real time implementation of this algorithm for on-line use. The algorithm is tested on over 500 images of slurry and is found to segment and characterize nonuniformities on all 500 images.

  14. Enhanced Modeling of Remotely Sensed Annual Land Surface Temperature Cycle

    Science.gov (United States)

    Zou, Z.; Zhan, W.; Jiang, L.

    2017-09-01

    Satellite thermal remote sensing provides access to acquire large-scale Land surface temperature (LST) data, but also generates missing and abnormal values resulting from non-clear-sky conditions. Given this limitation, Annual Temperature Cycle (ATC) model was employed to reconstruct the continuous daily LST data over a year. The original model ATCO used harmonic functions, but the dramatic changes of the real LST caused by the weather changes remained unclear due to the smooth sine curve. Using Aqua/MODIS LST products, NDVI and meteorological data, we proposed enhanced model ATCE based on ATCO to describe the fluctuation and compared their performances for the Yangtze River Delta region of China. The results demonstrated that, the overall root mean square errors (RMSEs) of the ATCE was lower than ATCO, and the improved accuracy of daytime was better than that of night, with the errors decreased by 0.64 K and 0.36 K, respectively. The improvements of accuracies varied with different land cover types: the forest, grassland and built-up areas improved larger than water. And the spatial heterogeneity was observed for performance of ATC model: the RMSEs of built-up area, forest and grassland were around 3.0 K in the daytime, while the water attained 2.27 K; at night, the accuracies of all types significantly increased to similar RMSEs level about 2 K. By comparing the differences between LSTs simulated by two models in different seasons, it was found that the differences were smaller in the spring and autumn, while larger in the summer and winter.

  15. Analytical modelling for ultrasonic surface mechanical attrition treatment

    Directory of Open Access Journals (Sweden)

    Guan-Rong Huang

    2015-07-01

    Full Text Available The grain refinement, gradient structure, fatigue limit, hardness, and tensile strength of metallic materials can be effectively enhanced by ultrasonic surface mechanical attrition treatment (SMAT, however, never before has SMAT been treated with rigorous analytical modelling such as the connection among the input energy and power and resultant temperature of metallic materials subjected to SMAT. Therefore, a systematic SMAT model is actually needed. In this article, we have calculated the averaged speed, duration time of a cycle, kinetic energy and kinetic energy loss of flying balls in SMAT for structural metallic materials. The connection among the quantities such as the frequency and amplitude of attrition ultrasonic vibration motor, the diameter, mass and density of balls, the sample mass, and the height of chamber have been considered and modelled in details. And we have introduced the one-dimensional heat equation with heat source within uniform-distributed depth in estimating the temperature distribution and heat energy of sample. In this approach, there exists a condition for the frequency of flying balls reaching a steady speed. With these known quantities, we can estimate the strain rate, hardness, and grain size of sample.

  16. Modelling of a free-surface ferrofluid flow

    Science.gov (United States)

    Habera, M.; Hron, J.

    2017-06-01

    The Cauchy's stress tensor of a ferrofluid exposed to an external magnetic field is subject to additional magnetic terms. For a linearly magnetizable medium, the terms result in interfacial magnetic force acting on the ferrofluid boundaries. This force changes the characteristics of many free-surface ferrofluid phenomena. The aim of this work is to implement this force into the incompressible Navier-Stokes equations and propose a numerical method to solve them. The interface of ferrofluid is tracked with the use of the characteristic level-set method and additional reinitialization step assures conservation of its volume. Incompressible Navier-Stokes equations are formulated for a divergence-free velocity fields while discrete interfacial forces are treated with continuous surface force model. Velocity-pressure coupling is implemented via the projection method. To predict the magnetic force effect quantitatively, Maxwell's equations for magnetostatics are solved in each time step. Finite element method is utilized for the spatial discretization. At the end of the work, equilibrium droplet shape are compared to known experimental results.

  17. Accuracy Assessment for Cad Modeling of Freeform Surface Described by Equation

    Directory of Open Access Journals (Sweden)

    Golba Grzegorz

    2015-06-01

    Full Text Available This paper presents the results of comparative analysis of modeling accuracy the freeform surface constructed by using a variety of algorithms for surface modeling. Also determined the accuracy of mapping the theoretical freeform surface described by mathematical equation. To model surface objects used: SolidWorks 2012, CATIA v5 and Geomagic Studio 12. During the design process of CAD models were used: profile curves, fitting parametric surface and polygonal mesh. To assess the accuracy of the CAD models used Geomagic Qualify 12. On the basis of analyse defined the scope of application of each modeling techniques depending on the nature of the constructed object.

  18. Multiscale modelling of hydrogen behaviour on beryllium (0001 surface

    Directory of Open Access Journals (Sweden)

    Ch. Stihl

    2016-12-01

    Full Text Available Beryllium is proposed to be a neutron multiplier and plasma facing material in future fusion devices. Therefore, it is crucial to acquire an understanding of the microscopic mechanisms of tritium accumulation and release as a result of transmutation processes that Be undergoes under neutron irradiation. A multiscale simulation of ad- and desorption of hydrogen isotopes on the beryllium (0001 surface is developed. It consists of ab initio calculations of certain H adsorption configurations, a suitable cluster expansion approximating the energies of arbitrary configurations, and a kinetic Monte Carlo method for dynamic simulations of adsorption and desorption. The processes implemented in the kinetic Monte Carlo simulation are deduced from further ab initio calculations comprising both, static relaxation as well as molecular dynamics runs. The simulation is used to reproduce experimental data and the results are compared and discussed. Based on the observed results, proposals for a refined model are made.

  19. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

    OpenAIRE

    Khayet, Mohamed; Fernandez Fernandez, Victoria

    2012-01-01

    Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we int...

  20. Modeling seasonal surface temperature variations in secondary tropical dry forests

    Science.gov (United States)

    Cao, Sen; Sanchez-Azofeifa, Arturo

    2017-10-01

    Secondary tropical dry forests (TDFs) provide important ecosystem services such as carbon sequestration, biodiversity conservation, and nutrient cycle regulation. However, their biogeophysical processes at the canopy-atmosphere interface remain unknown, limiting our understanding of how this endangered ecosystem influences, and responds to the ongoing global warming. To facilitate future development of conservation policies, this study characterized the seasonal land surface temperature (LST) behavior of three successional stages (early, intermediate, and late) of a TDF, at the Santa Rosa National Park (SRNP), Costa Rica. A total of 38 Landsat-8 Thermal Infrared Sensor (TIRS) data and the Surface Reflectance (SR) product were utilized to model LST time series from July 2013 to July 2016 using a radiative transfer equation (RTE) algorithm. We further related the LST time series to seven vegetation indices which reflect different properties of TDFs, and soil moisture data obtained from a Wireless Sensor Network (WSN). Results showed that the LST in the dry season was 15-20 K higher than in the wet season at SRNP. We found that the early successional stages were about 6-8 K warmer than the intermediate successional stages and were 9-10 K warmer than the late successional stages in the middle of the dry season; meanwhile, a minimum LST difference (0-1 K) was observed at the end of the wet season. Leaf phenology and canopy architecture explained most LST variations in both dry and wet seasons. However, our analysis revealed that it is precipitation that ultimately determines the LST variations through both biogeochemical (leaf phenology) and biogeophysical processes (evapotranspiration) of the plants. Results of this study could help physiological modeling studies in secondary TDFs.

  1. Land surface evapotranspiration modelling at the regional scale

    Science.gov (United States)

    Raffelli, Giulia; Ferraris, Stefano; Canone, Davide; Previati, Maurizio; Gisolo, Davide; Provenzale, Antonello

    2017-04-01

    minimal point of soil moisture that plant requires not to wilt); the field capacity (i.e. the maximum amount of water content that a soil can held); the available water content (AWC), obtained as the difference between field capacity and wilting point. Furthermore, the model considers 15 different ID of land use, with a resolution of 250 m. The model was then tested by a direct comparison with experimental data. First, the modelled water content from the surface down to 65 cm of soil depth was compared to the measured one with a Time Domain Reflectometry (TDR) in Grugliasco (TO), a non-irrigated flat permanent meadow, for years 2006-2008. Here, the soil is sandy with a slope of about 1%. Then, considering three corn farms located in the Cuneo district, the goodness of modelled irrigations was verified. The soil texture of the three farms, analysed according to the USDA criteria, is loam or silty-loam. In particular, we compared the number of irrigations done by the farmers with the ones given by the model, which irrigates as soon as the plant reaches an imposed level of water stress. We also compared the irrigation turn given by the model with the farmers' one. Then we compared the modelled water content with the one measured before and after the irrigation. We observed that the modelled irrigation occurred when the measured water content was close to the modelled wilting point. In both test cases, the model seems to reflect quite well the real behaviour of water content.

  2. Physically plausible prescription of land surface model soil moisture

    Science.gov (United States)

    Hauser, Mathias; Orth, René; Thiery, Wim; Seneviratne, Sonia

    2016-04-01

    Land surface hydrology is an important control of surface weather and climate, especially under extreme dry or wet conditions where it can amplify heat waves or floods, respectively. Prescribing soil moisture in land surface models is a valuable technique to investigate this link between hydrology and climate. It has been used for example to assess the influence of soil moisture on temperature variability, mean and extremes (Seneviratne et al. 2006, 2013, Lorenz et al., 2015). However, perturbing the soil moisture content artificially can lead to a violation of the energy and water balances. Here we present a new method for prescribing soil moisture which ensures water and energy balance closure by using only water from runoff and a reservoir term. If water is available, the method prevents soil moisture decrease below climatological values. Results from simulations with the Community Land Model (CLM) indicate that our new method allows to avoid soil moisture deficits in many regions of the world. We show the influence of the irrigation-supported soil moisture content on mean and extreme temperatures and contrast our findings with that of earlier studies. Additionally, we will assess how long into the 21st century the new method will be able to maintain present-day climatological soil moisture levels for different regions. Lorenz, R., Argüeso, D., Donat, M.G., Pitman, A.J., den Hurk, B.V., Berg, A., Lawrence, D.M., Chéruy, F., Ducharne, A., Hagemann, S. and Meier, A., 2015. Influence of land-atmosphere feedbacks on temperature and precipitation extremes in the GLACE-CMIP5 ensemble. Journal of Geophysical Research: Atmospheres. Seneviratne, S.I., Lüthi, D., Litschi, M. and Schär, C., 2006. Land-atmosphere coupling and climate change in Europe. Nature, 443(7108), pp.205-209. Seneviratne, S.I., Wilhelm, M., Stanelle, T., Hurk, B., Hagemann, S., Berg, A., Cheruy, F., Higgins, M.E., Meier, A., Brovkin, V. and Claussen, M., 2013. Impact of soil moisture

  3. GEOQUIMICO : an interactive tool for comparing sorption conceptual models (surface complexation modeling versus K[D])

    International Nuclear Information System (INIS)

    Hammond, Glenn E.; Cygan, Randall Timothy

    2007-01-01

    Within reactive geochemical transport, several conceptual models exist for simulating sorption processes in the subsurface. Historically, the K D approach has been the method of choice due to ease of implementation within a reactive transport model and straightforward comparison with experimental data. However, for modeling complex sorption phenomenon (e.g. sorption of radionuclides onto mineral surfaces), this approach does not systematically account for variations in location, time, or chemical conditions, and more sophisticated methods such as a surface complexation model (SCM) must be utilized. It is critical to determine which conceptual model to use; that is, when the material variation becomes important to regulatory decisions. The geochemical transport tool GEOQUIMICO has been developed to assist in this decision-making process. GEOQUIMICO provides a user-friendly framework for comparing the accuracy and performance of sorption conceptual models. The model currently supports the K D and SCM conceptual models. The code is written in the object-oriented Java programming language to facilitate model development and improve code portability. The basic theory underlying geochemical transport and the sorption conceptual models noted above is presented in this report. Explanations are provided of how these physicochemical processes are instrumented in GEOQUIMICO and a brief verification study comparing GEOQUIMICO results to data found in the literature is given

  4. Modeling of circular-grating surface-emitting lasers

    Science.gov (United States)

    Shams-Zadeh-Amiri, Ali M.

    Grating-coupled surface-emitting lasers became an area of growing interest due to their salient features. Emission from a broad area normal to the wafer surface, makes them very well suited in high power applications and two- dimensional laser arrays. These new possibilities have caused an interest in different geometries to fully develop their potential. Among them, circular-grating lasers have the additional advantage of producing a narrow beam with a circular cross section. This special feature makes them ideal for coupling to optical fibers. All existing theoretical models dealing with circular- grating lasers only consider first-order gratings, or second-order gratings, neglecting surface emission. In this thesis, the emphasis is to develop accurate models describing the laser performance by considering the radiation field. Toward this aim, and due to the importance of the radiation modes in surface-emitting structures, a theoretical study of these modes in multilayer planar structures has been done in a rigorous and systematic fashion. Problems like orthogonality of the radiation modes have been treated very accurately. We have considered the inner product of radiation modes using the distribution theory. Orthogonality of degenerate radiation modes is an important issue. We have examined its validity using the transfer matrix method. It has been shown that orthogonality of degenerate radiation modes in a very special case leads to the Brewster theorem. In addition, simple analytical formulas for the normalization of radiation modes have been derived. We have shown that radiation modes can be handled in a much easier way than has been thought before. A closed-form spectral dyadic Green's function formulation of multilayer planar structures has been developed. In this formulation, both rectangular and cylindrical structures can be treated within the same mathematical framework. The Hankel transform of some auxiliary functions defined on a circular aperture has

  5. Influence of urban surface properties and rainfall characteristics on surface water flood outputs - insights from a physical modelling environment

    Science.gov (United States)

    Green, Daniel; Pattison, Ian; Yu, Dapeng

    2017-04-01

    Surface water (pluvial) flooding occurs when excess rainfall from intense precipitation events is unable to infiltrate into the subsurface or drain via natural or artificial drainage channels. Surface water flood events pose a major hazard to urban regions across the world, with nearly two thirds of flood damages in the UK being caused by surface water flood events. The perceived risk of surface water flooding appears to have increased in recent years due to several factors, including (i) precipitation increases associated with climatic change and variability; (ii) population growth meaning more people are occupying flood risk areas, and; (iii) land-use changes. Because urban areas are often associated with a high proportion of impermeable land-uses (e.g. tarmacked or paved surfaces and buildings) and a reduced coverage of vegetated, permeable surfaces, urban surface water flood risk during high intensity precipitation events is often exacerbated. To investigate the influence of urbanisation and terrestrial factors on surface water flood outputs, rainfall intensity, catchment slope, permeability, building density/layout scenarios were designed within a novel, 9m2 physical modelling environment. The two-tiered physical model used consists of (i) a low-cost, nozzle-type rainfall simulator component which is able to simulate consistent, uniformly distributed rainfall events of varying duration and intensity, and; (ii) a reconfigurable, modular plot surface. All experiments within the physical modelling environment were subjected to a spatiotemporally uniform 45-minute simulated rainfall event, while terrestrial factors on the physical model plot surface were altered systematically to investigate their hydrological response on modelled outflow and depth profiles. Results from the closed, controlled physical modelling experiments suggest that meteorological factors, such as the duration and intensity of simulated rainfall, and terrestrial factors, such as model slope

  6. Multilevel Thoracolumbar Spondylolysis with Spondylolisthesis at L4 on L5.

    Science.gov (United States)

    Kim, Whoan Jeang; Song, Young Dong; Choy, Won Sik

    2015-09-01

    A 24-year-old male patient was initially evaluated for persistent back pain. The visual analogue scale (VAS) score was 7 points. Physical examination revealed a decreased range of lumbar spinal motion, which caused pain. Simple X-ray revealed Meyerding grade 1 spondylolisthesis at L4 on L5, with mild dome-shaped superior endplate and consecutive multilevel spondylolysis at T12-L5. Standing anteroposterior and lateral views of the entire spine revealed normal balance of sagittal and coronal alignment. A computed tomography scan revealed bilateral spondylolysis at T12-L4, left unilateral spondylolysis at L5, and spina bifida at L5 to sacral region. Magnetic resonance imaging revealed mild dural ectasia at the lumbar region. Due to the absence of any neurological symptoms, the patient was managed conservatively. He was rested a few weeks with corset brace and physiotherapy. After treatment, his back pain improved, VAS score changed from 7 to 2, and he was able to return to normal activity.

  7. Surface system Forsmark. Site descriptive modelling SDM-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Lindborg, Tobias (ed.)

    2008-12-15

    SKB has undertaken site characterization of two different areas, Forsmark and Laxemar-Simpevarp, in order to find a suitable location for a geological repository for spent nuclear fuel. This report focuses on the site descriptive modelling of the surface system at Forsmark. The characterization of the surface system at the site was primarily made by identifying and describing important properties in different parts of the surface system, properties concerning e.g. hydrology and climate, Quaternary deposits and soils, hydrochemistry, vegetation, ecosystem functions, but also current and historical land use. The report presents available input data, methodology for data evaluation and modelling, and resulting models for each of the different disciplines. Results from the modelling of the surface system are also integrated with results from modelling of the deep bedrock system. The Forsmark site is located within the municipality of Oesthammar, about 120 km north of Stockholm. The investigated area is located along the shoreline of Oeregrundsgrepen, a funnel-shaped bay of the Baltic Sea. The area is characterized by small-scale topographic variations and is almost entirely located at altitudes lower than 20 metres above sea level. The Quaternary deposits in the area are dominated by till, characterized by a rich content of calcite which was transported by the glacier ice to the area from the sedimentary bedrock of Gaevlebukten about 100 km north of Forsmark. As a result, the surface waters and shallow groundwater at Forsmark are characterized by high pH values and high concentrations of certain major constituents, especially calcium and bicarbonate. The annual precipitation and runoff are 560 and 150 mm, respectively. The lakes are small and shallow, with mean and maximum depths ranging from approximately 0.1 to 1 m and 0.4 to 2 m. Sea water flows into the most low-lying lakes during events giving rise to very high sea levels. Wetlands are frequent and cover 25 to 35

  8. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions.

    Science.gov (United States)

    Khayet, Mohamed; Fernández, Victoria

    2012-11-14

    Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions.

  9. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

    Science.gov (United States)

    2012-01-01

    Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions. PMID:23151272

  10. Molecular Modeling of Diffusion on a Crystalline PETN Surface

    Energy Technology Data Exchange (ETDEWEB)

    Lin, P; Khare, R; Gee, R H; Weeks, B L

    2007-07-13

    Surface diffusion on a PETN crystal was investigated by treating the surface diffusion as an activated process in the formalism of transition state theory. In particular, surface diffusion on the (110) and (101) facets, as well as diffusion between these facets, were considered. We successfully obtained the potential energy barriers required for PETN surface diffusion. Our results show that the (110) surface is more thermally active than the (101) surface and PETN molecules mainly diffuses from the (110) to (101) facet. These results are in good agreement with experimental observations and previous simulations.

  11. Effective 3-D surface modeling for geographic information systems

    Science.gov (United States)

    Yüksek, K.; Alparslan, M.; Mendi, E.

    2016-01-01

    In this work, we propose a dynamic, flexible and interactive urban digital terrain platform with spatial data and query processing capabilities of geographic information systems, multimedia database functionality and graphical modeling infrastructure. A new data element, called Geo-Node, which stores image, spatial data and 3-D CAD objects is developed using an efficient data structure. The system effectively handles data transfer of Geo-Nodes between main memory and secondary storage with an optimized directional replacement policy (DRP) based buffer management scheme. Polyhedron structures are used in digital surface modeling and smoothing process is performed by interpolation. The experimental results show that our framework achieves high performance and works effectively with urban scenes independent from the amount of spatial data and image size. The proposed platform may contribute to the development of various applications such as Web GIS systems based on 3-D graphics standards (e.g., X3-D and VRML) and services which integrate multi-dimensional spatial information and satellite/aerial imagery.

  12. Poisson sigma model with branes and hyperelliptic Riemann surfaces

    International Nuclear Information System (INIS)

    Ferrario, Andrea

    2008-01-01

    We derive the explicit form of the superpropagators in the presence of general boundary conditions (coisotropic branes) for the Poisson sigma model. This generalizes the results presented by Cattaneo and Felder [''A path integral approach to the Kontsevich quantization formula,'' Commun. Math. Phys. 212, 591 (2000)] and Cattaneo and Felder ['Coisotropic submanifolds in Poisson geometry and branes in the Poisson sigma model', Lett. Math. Phys. 69, 157 (2004)] for Kontsevich's angle function [Kontsevich, M., 'Deformation quantization of Poisson manifolds I', e-print arXiv:hep.th/0101170] used in the deformation quantization program of Poisson manifolds. The relevant superpropagators for n branes are defined as gauge fixed homotopy operators of a complex of differential forms on n sided polygons P n with particular ''alternating'' boundary conditions. In the presence of more than three branes we use first order Riemann theta functions with odd singular characteristics on the Jacobian variety of a hyperelliptic Riemann surface (canonical setting). In genus g the superpropagators present g zero mode contributions

  13. Surface pH controls purple-to-blue transition of bacteriorhodopsin. A theoretical model of purple membrane surface

    OpenAIRE

    Szundi, I.; Stoeckenius, W.

    1989-01-01

    We have developed a surface model of purple membrane and applied it in an analysis of the purple-to-blue color change of bacteriorhodopsin which is induced by acidification or deionization. The model is based on dissociation and double layer theory and the known membrane structure. We calculated surface pH, ion concentrations, charge density, and potential as a function of bulk pH and concentration of mono- and divalent cations. At low salt concentrations, the surface pH is significantly lowe...

  14. A NEW APPROACH OF DIGITAL BRIDGE SURFACE MODEL GENERATION

    Directory of Open Access Journals (Sweden)

    H. Ju

    2012-07-01

    Full Text Available Bridge areas present difficulties for orthophotos generation and to avoid “collapsed” bridges in the orthoimage, operator assistance is required to create the precise DBM (Digital Bridge Model, which is, subsequently, used for the orthoimage generation. In this paper, a new approach of DBM generation, based on fusing LiDAR (Light Detection And Ranging data and aerial imagery, is proposed. The no precise exterior orientation of the aerial image is required for the DBM generation. First, a coarse DBM is produced from LiDAR data. Then, a robust co-registration between LiDAR intensity and aerial image using the orientation constraint is performed. The from-coarse-to-fine hybrid co-registration approach includes LPFFT (Log-Polar Fast Fourier Transform, Harris Corners, PDF (Probability Density Function feature descriptor mean-shift matching, and RANSAC (RANdom Sample Consensus as main components. After that, bridge ROI (Region Of Interest from LiDAR data domain is projected to the aerial image domain as the ROI in the aerial image. Hough transform linear features are extracted in the aerial image ROI. For the straight bridge, the 1st order polynomial function is used; whereas, for the curved bridge, 2nd order polynomial function is used to fit those endpoints of Hough linear features. The last step is the transformation of the smooth bridge boundaries from aerial image back to LiDAR data domain and merge them with the coarse DBM. Based on our experiments, this new approach is capable of providing precise DBM which can be further merged with DTM (Digital Terrain Model derived from LiDAR data to obtain the precise DSM (Digital Surface Model. Such a precise DSM can be used to improve the orthophoto product quality.

  15. Surface complexation model of uranyl sorption on Georgia kaolinite

    Science.gov (United States)

    Payne, T.E.; Davis, J.A.; Lumpkin, G.R.; Chisari, R.; Waite, T.D.

    2004-01-01

    The adsorption of uranyl on standard Georgia kaolinites (KGa-1 and KGa-1B) was studied as a function of pH (3-10), total U (1 and 10 ??mol/l), and mass loading of clay (4 and 40 g/l). The uptake of uranyl in air-equilibrated systems increased with pH and reached a maximum in the near-neutral pH range. At higher pH values, the sorption decreased due to the presence of aqueous uranyl carbonate complexes. One kaolinite sample was examined after the uranyl uptake experiments by transmission electron microscopy (TEM), using energy dispersive X-ray spectroscopy (EDS) to determine the U content. It was found that uranium was preferentially adsorbed by Ti-rich impurity phases (predominantly anatase), which are present in the kaolinite samples. Uranyl sorption on the Georgia kaolinites was simulated with U sorption reactions on both titanol and aluminol sites, using a simple non-electrostatic surface complexation model (SCM). The relative amounts of U-binding >TiOH and >AlOH sites were estimated from the TEM/EDS results. A ternary uranyl carbonate complex on the titanol site improved the fit to the experimental data in the higher pH range. The final model contained only three optimised log K values, and was able to simulate adsorption data across a wide range of experimental conditions. The >TiOH (anatase) sites appear to play an important role in retaining U at low uranyl concentrations. As kaolinite often contains trace TiO2, its presence may need to be taken into account when modelling the results of sorption experiments with radionuclides or trace metals on kaolinite. ?? 2004 Elsevier B.V. All rights reserved.

  16. Response Surface Modeling Tool Suite, Version 1.x

    Energy Technology Data Exchange (ETDEWEB)

    2016-07-05

    The Response Surface Modeling (RSM) Tool Suite is a collection of three codes used to generate an empirical interpolation function for a collection of drag coefficient calculations computed with Test Particle Monte Carlo (TPMC) simulations. The first code, "Automated RSM", automates the generation of a drag coefficient RSM for a particular object to a single command. "Automated RSM" first creates a Latin Hypercube Sample (LHS) of 1,000 ensemble members to explore the global parameter space. For each ensemble member, a TPMC simulation is performed and the object drag coefficient is computed. In the next step of the "Automated RSM" code, a Gaussian process is used to fit the TPMC simulations. In the final step, Markov Chain Monte Carlo (MCMC) is used to evaluate the non-analytic probability distribution function from the Gaussian process. The second code, "RSM Area", creates a look-up table for the projected area of the object based on input limits on the minimum and maximum allowed pitch and yaw angles and pitch and yaw angle intervals. The projected area from the look-up table is used to compute the ballistic coefficient of the object based on its pitch and yaw angle. An accurate ballistic coefficient is crucial in accurately computing the drag on an object. The third code, "RSM Cd", uses the RSM generated by the "Automated RSM" code and the projected area look-up table generated by the "RSM Area" code to accurately compute the drag coefficient and ballistic coefficient of the object. The user can modify the object velocity, object surface temperature, the translational temperature of the gas, the species concentrations of the gas, and the pitch and yaw angles of the object. Together, these codes allow for the accurate derivation of an object's drag coefficient and ballistic coefficient under any conditions with only knowledge of the object's geometry and mass.

  17. Surface models of the male urogenital organs built from the Visible Korean using popular software

    Science.gov (United States)

    Shin, Dong Sun; Park, Jin Seo; Shin, Byeong-Seok

    2011-01-01

    Unlike volume models, surface models, which are empty three-dimensional images, have a small file size, so they can be displayed, rotated, and modified in real time. Thus, surface models of male urogenital organs can be effectively applied to an interactive computer simulation and contribute to the clinical practice of urologists. To create high-quality surface models, the urogenital organs and other neighboring structures were outlined in 464 sectioned images of the Visible Korean male using Adobe Photoshop; the outlines were interpolated on Discreet Combustion; then an almost automatic volume reconstruction followed by surface reconstruction was performed on 3D-DOCTOR. The surface models were refined and assembled in their proper positions on Maya, and a surface model was coated with actual surface texture acquired from the volume model of the structure on specially programmed software. In total, 95 surface models were prepared, particularly complete models of the urinary and genital tracts. These surface models will be distributed to encourage other investigators to develop various kinds of medical training simulations. Increasingly automated surface reconstruction technology using commercial software will enable other researchers to produce their own surface models more effectively. PMID:21829759

  18. Numerical model of rainwater runoff over the catchment surface and ...

    African Journals Online (AJOL)

    ... runoff along the surface catchment and transport of impurity which permeates into the water flow from soil at the certain areas of this surface. This system consists of two types of equations: the first of them describes the changes of water layer thickness over the slope surface given the precipitation and evaporation, and the ...

  19. Chiropractic and rehabilitation management of a patient with extraforaminal entrapment of L4 nerve with balance problem.

    Science.gov (United States)

    Alagha, Babak

    2015-01-01

    Disc herniation is one of the most common causes of low back pain with radicular pain. Among various types of disc herniation, the extraforaminal disc herniation is a rare cause of lumbar radiculopathy. The aim of presenting this case study is to demonstrate the benefits of Chiropractic care including spine and extremity manipulation and rehabilitation in the treatment of a rare case of extraforaminal L4 nerve entrapment causing severe L4 radiculopathy and chronic mild low back pain (LBP). The aim of presenting this case study is to demonstrate the benefits of Chiropractic care including spine and extremity manipulation and rehabilitation in treatment of rare case of extraforaminal L4 nerve entrapment which caused severe L4 radiculopathy and chronic mild low back pain (LBP). A 45-year old female patient arrived at the clinic with chronic mild low back pain and right buttock pain, all of which had presented for two years' duration. During the preceding month, the radicular pain initiated in medium to high intensity, radiating to her right leg following the L4 dermatomal pattern with a periodic tingling sensation in her right foot. A neuro exam demonstrated a proprioception deficit in her right leg. A Romberg test was positive. The patient was treated by low amplitude high velocity spinal and extremity manipulation for 10 consecutive sessions (2 weeks), followed by rehabilitation and exercise therapy including advanced myofascial release therapy for an additional 12 sessions (4 weeks). After treatment, the patient reported a significant improvement in her low back pain and radiculopathy. In addition, she achieved some improvement in balance. It seems that Chiropractic care and rehabilitation therapy may be a safe and effective modality in treatment of an L4 radiculopathy in a patient with an extraforaminal L4 nerve entrapment. Although it is rare, an L4 extraforaminal disc herniation should be considered as a possible cause of symptoms in patients with chronic mild

  20. [Application of three compartment model and response surface model to clinical anesthesia using Microsoft Excel].

    Science.gov (United States)

    Abe, Eiji; Abe, Mari

    2011-08-01

    With the spread of total intravenous anesthesia, clinical pharmacology has become more important. We report Microsoft Excel file applying three compartment model and response surface model to clinical anesthesia. On the Microsoft Excel sheet, propofol, remifentanil and fentanyl effect-site concentrations are predicted (three compartment model), and probabilities of no response to prodding, shaking, surrogates of painful stimuli and laryngoscopy are calculated using predicted effect-site drug concentration. Time-dependent changes in these calculated values are shown graphically. Recent development in anesthetic drug interaction studies are remarkable, and its application to clinical anesthesia with this Excel file is simple and helpful for clinical anesthesia.

  1. A nonlinear model for surface segregation and solute trapping during planar film growth

    International Nuclear Information System (INIS)

    Han, Xiaoying; Spencer, Brian J.

    2007-01-01

    Surface segregation and solute trapping during planar film growth is one of the important issues in molecular beam epitaxy, yet the study on surface composition has been largely restricted to experimental work. This paper introduces some mathematical models of surface composition during planar film growth. Analytical solutions are obtained for the surface composition during growth

  2. Size of isospin breaking in charged $K_{l4}$ decay

    CERN Document Server

    Nehme, A

    2005-01-01

    We evaluate the size of isospin breaking corrections to form factors f and g of the K/sub l4/ decay process K/sup +/ to pi /sup +/ pi /sup -/l/sup +/vl which is actually measured by the extended NA48 setup at CERN. We found that, keeping apart the effect of Coulomb interaction, isospin breaking does not affect the moduli. This is due to the cancellation between corrections of electromagnetic origin and those generated by the difference between up and down quark masses. On the other hand, electromagnetism affects considerably the phases if the infrared divergence is dropped out using a minimal subtraction scheme. Consequently, the greatest care must be taken in the extraction of pi pi phase shifts from experiment.

  3. Progress of and future plans for the L-4 Blanket Project

    International Nuclear Information System (INIS)

    Daenner, W.; Ioki, K.; Cardella, A.

    2001-01-01

    The ITER L-4 Blanket Project has achieved substantial progress over the last two years. The qualification of materials so far considered as reference for the shield module fabrication has been completed, as well as the developments for joining the triplex First Wall structure. Several Primary Wall, baffle, and limiter mock-ups have been manufactured and tested showing comfortable margins against the loads expected in ITER. Shield prototypes have been manufactured by conventional and advanced technology, which have finally demonstrated the manufacturing feasibility. More recently, activities for the qualification of the module attachment system have been started, and first results from materials and mock-up tests have become available. Several test campaigns are still to be finished to complete the data base for the design. In the meantime, further activities have been initiated to adapt the R and D programme to the ITER-FEAT design features, with the aim to further reduce the cost. (author)

  4. Understanding SMAP-L4 soil moisture estimation skill and their dependence with topography, precipitation and vegetation type using Mesonet and Micronet networks.

    Science.gov (United States)

    Moreno, H. A.; Basara, J. B.; Thompson, E.; Bertrand, D.; Johnston, C. S.

    2017-12-01

    Soil moisture measurements using satellite information can benefit from a land data assimilation model Goddard Earth Observing System (GEOS-5) and land data assimilation system (LDAS) to improve the representation of fine-scale dynamics and variability. This work presents some advances to understand the predictive skill of L4-SM product across different land-cover types, topography and precipitation totals, by using a dense network of multi-level soil moisture sensors (i.e. Mesonet and Micronet) in Oklahoma. 130 soil moisture stations are used across different precipitation gradients (i.e. arid vs wet), land cover (e.g. forest, shrubland, grasses, crops), elevation (low, mid and high) and slope to assess the improvements by the L4_SM product relative to the raw SMAP L-band brightness temperatures. The comparisons are conducted between July 2015 and July 2016 at the daily time scale. Results show the highest L4-SM overestimations occur in pastures and cultivated crops, during the rainy season and at higher elevation lands (over 800 meters asl). The smallest errors occur in low elevation lands, low rainfall and developed lands. Forested area's soil moisture biases lie in between pastures (max biases) and low intensity/developed lands (min biases). Fine scale assessment of L4-SM should help GEOS-5 and LDAS teams refine model parameters in light of observed differences and improve assimilation techniques in light of land-cover, topography and precipitation regime. Additionally, regional decision makers could have a framework to weight the utility of this product for water resources applications.

  5. 2-way coupling the hydrological land surface model PROMET with the regional climate model MM5

    Directory of Open Access Journals (Sweden)

    F. Zabel

    2013-05-01

    Full Text Available Most land surface hydrological models (LSHMs consider land surface processes (e.g. soil–plant–atmosphere interactions, lateral water flows, snow and ice in a spatially detailed manner. The atmosphere is considered as exogenous driver, neglecting feedbacks between the land surface and the atmosphere. On the other hand, regional climate models (RCMs generally simulate land surface processes through coarse descriptions and spatial scales but include land–atmosphere interactions. What is the impact of the differently applied model physics and spatial resolution of LSHMs on the performance of RCMs? What feedback effects are induced by different land surface models? This study analyses the impact of replacing the land surface module (LSM within an RCM with a high resolution LSHM. A 2-way coupling approach was applied using the LSHM PROMET (1 × 1 km2 and the atmospheric part of the RCM MM5 (45 × 45 km2. The scaling interface SCALMET is used for down- and upscaling the linear and non-linear fluxes between the model scales. The change in the atmospheric response by MM5 using the LSHM is analysed, and its quality is compared to observations of temperature and precipitation for a 4 yr period from 1996 to 1999 for the Upper Danube catchment. By substituting the Noah-LSM with PROMET, simulated non-bias-corrected near-surface air temperature improves for annual, monthly and daily courses when compared to measurements from 277 meteorological weather stations within the Upper Danube catchment. The mean annual bias was improved from −0.85 to −0.13 K. In particular, the improved afternoon heating from May to September is caused by increased sensible heat flux and decreased latent heat flux as well as more incoming solar radiation in the fully coupled PROMET/MM5 in comparison to the NOAH/MM5 simulation. Triggered by the LSM replacement, precipitation overall is reduced; however simulated precipitation amounts are still of high uncertainty, both

  6. Assessment of Land Surface Models in a High-Resolution Atmospheric Model during Indian Summer Monsoon

    Science.gov (United States)

    Attada, Raju; Kumar, Prashant; Dasari, Hari Prasad

    2018-04-01

    Assessment of the land surface models (LSMs) on monsoon studies over the Indian summer monsoon (ISM) region is essential. In this study, we evaluate the skill of LSMs at 10 km spatial resolution in simulating the 2010 monsoon season. The thermal diffusion scheme (TDS), rapid update cycle (RUC), and Noah and Noah with multi-parameterization (Noah-MP) LSMs are chosen based on nature of complexity, that is, from simple slab model to multi-parameterization options coupled with the Weather Research and Forecasting (WRF) model. Model results are compared with the available in situ observations and reanalysis fields. The sensitivity of monsoon elements, surface characteristics, and vertical structures to different LSMs is discussed. Our results reveal that the monsoon features are reproduced by WRF model with all LSMs, but with some regional discrepancies. The model simulations with selected LSMs are able to reproduce the broad rainfall patterns, orography-induced rainfall over the Himalayan region, and dry zone over the southern tip of India. The unrealistic precipitation pattern over the equatorial western Indian Ocean is simulated by WRF-LSM-based experiments. The spatial and temporal distributions of top 2-m soil characteristics (soil temperature and soil moisture) are well represented in RUC and Noah-MP LSM-based experiments during the ISM. Results show that the WRF simulations with RUC, Noah, and Noah-MP LSM-based experiments significantly improved the skill of 2-m temperature and moisture compared to TDS (chosen as a base) LSM-based experiments. Furthermore, the simulations with Noah, RUC, and Noah-MP LSMs exhibit minimum error in thermodynamics fields. In case of surface wind speed, TDS LSM performed better compared to other LSM experiments. A significant improvement is noticeable in simulating rainfall by WRF model with Noah, RUC, and Noah-MP LSMs over TDS LSM. Thus, this study emphasis the importance of choosing/improving LSMs for simulating the ISM phenomena in

  7. Impacts of model initialization on an integrated surface water - groundwater model

    KAUST Repository

    Ajami, Hoori

    2015-04-01

    Integrated hydrologic models characterize catchment responses by coupling the subsurface flow with land surface processes. One of the major areas of uncertainty in such models is the specification of the initial condition and its influence on subsequent simulations. A key challenge in model initialization is that it requires spatially distributed information on model states, groundwater levels and soil moisture, even when such data are not routinely available. Here, the impact of uncertainty in initial condition was explored across a 208 km2 catchment in Denmark using the ParFlow.CLM model. The initialization impact was assessed under two meteorological conditions (wet vs dry) using five depth to water table and soil moisture distributions obtained from various equilibrium states (thermal, root zone, discharge, saturated and unsaturated zone equilibrium) during the model spin-up. Each of these equilibrium states correspond to varying computation times to achieve stability in a particular aspect of the system state. Results identified particular sensitivity in modelled recharge and stream flow to the different initializations, but reduced sensitivity in modelled energy fluxes. Analysis also suggests that to simulate a year that is wetter than the spin-up period, an initialization based on discharge equilibrium is adequate to capture the direction and magnitude of surface water–groundwater exchanges. For a drier or hydrologically similar year to the spin-up period, an initialization based on groundwater equilibrium is required. Variability of monthly subsurface storage changes and discharge bias at the scale of a hydrological event show that the initialization impacts do not diminish as the simulations progress, highlighting the importance of robust and accurate initialization in capturing surface water–groundwater dynamics.

  8. Assessment of Land Surface Models in a High-Resolution Atmospheric Model during Indian Summer Monsoon

    KAUST Repository

    Attada, Raju

    2018-04-17

    Assessment of the land surface models (LSMs) on monsoon studies over the Indian summer monsoon (ISM) region is essential. In this study, we evaluate the skill of LSMs at 10 km spatial resolution in simulating the 2010 monsoon season. The thermal diffusion scheme (TDS), rapid update cycle (RUC), and Noah and Noah with multi-parameterization (Noah-MP) LSMs are chosen based on nature of complexity, that is, from simple slab model to multi-parameterization options coupled with the Weather Research and Forecasting (WRF) model. Model results are compared with the available in situ observations and reanalysis fields. The sensitivity of monsoon elements, surface characteristics, and vertical structures to different LSMs is discussed. Our results reveal that the monsoon features are reproduced by WRF model with all LSMs, but with some regional discrepancies. The model simulations with selected LSMs are able to reproduce the broad rainfall patterns, orography-induced rainfall over the Himalayan region, and dry zone over the southern tip of India. The unrealistic precipitation pattern over the equatorial western Indian Ocean is simulated by WRF–LSM-based experiments. The spatial and temporal distributions of top 2-m soil characteristics (soil temperature and soil moisture) are well represented in RUC and Noah-MP LSM-based experiments during the ISM. Results show that the WRF simulations with RUC, Noah, and Noah-MP LSM-based experiments significantly improved the skill of 2-m temperature and moisture compared to TDS (chosen as a base) LSM-based experiments. Furthermore, the simulations with Noah, RUC, and Noah-MP LSMs exhibit minimum error in thermodynamics fields. In case of surface wind speed, TDS LSM performed better compared to other LSM experiments. A significant improvement is noticeable in simulating rainfall by WRF model with Noah, RUC, and Noah-MP LSMs over TDS LSM. Thus, this study emphasis the importance of choosing/improving LSMs for simulating the ISM phenomena

  9. Collision and Break-off : Numerical models and surface observables

    Science.gov (United States)

    Bottrill, Andrew; van Hunen, Jeroen; Allen, Mark

    2013-04-01

    The process of continental collision and slab break-off has been explored by many authors using a number of different numerical models and approaches (Andrews and Billen, 2009; Gerya et al., 2004; van Hunen and Allen, 2011). One of the challenges of using numerical models to explore collision and break-off is relating model predictions to real observables from current collision zones. Part of the reason for this is that collision zones by their nature destroy a lot of potentially useful surface evidence of deep dynamics. One observable that offers the possibility for recording mantle dynamics at collision zones is topography. Here we present topography predictions from numerical models and show how these can be related to actual topography changes recoded in the sedimentary record. Both 2D and 3D numerical simulation of the closure of a small oceanic basin are presented (Bottrill et al., 2012; van Hunen and Allen, 2011). Topography is calculated from the normal stress at the surface applied to an elastic beam, to give a more realist prediction of topography by accounting for the expected elasticity of the lithosphere. Predicted model topography showed a number of interesting features on the overriding plate. The first is the formation of a basin post collision at around 300km from the suture. Our models also showed uplift postdating collision between the suture and this basin, caused by subduction of buoyant material. Once break-off has occurred we found that this uplift moved further into the overriding plate due to redistribution of stresses from the subducted plate. With our 3D numerical models we simulate a collision that propagates laterally along a subduction system. These models show that a basin forms, similar to that found in our 2D models, which propagates along the system at the same rate as collision. The apparent link between collision and basin formation leads to the investigation into the stress state in the overriding lithosphere. Preliminary

  10. A Unified 3D Spatial Data Model for Surface and Subsurface Spatial ...

    African Journals Online (AJOL)

    user

    surface. LoD maps for surface and subsurface integration exist for most city centres but the 3D component is lacking and this ... the integration of surface and subsurface models are discussed and a geometric, topological 3D object oriented model is sug- gested. .... dimensional (3D) continuous geological stratigraphy,.

  11. Snow specific surface area simulation using the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS

    Directory of Open Access Journals (Sweden)

    A. Roy

    2013-06-01

    Full Text Available Snow grain size is a key parameter for modeling microwave snow emission properties and the surface energy balance because of its influence on the snow albedo, thermal conductivity and diffusivity. A model of the specific surface area (SSA of snow was implemented in the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS version 3.4. This offline multilayer model (CLASS-SSA simulates the decrease of SSA based on snow age, snow temperature and the temperature gradient under dry snow conditions, while it considers the liquid water content of the snowpack for wet snow metamorphism. We compare the model with ground-based measurements from several sites (alpine, arctic and subarctic with different types of snow. The model provides simulated SSA in good agreement with measurements with an overall point-to-point comparison RMSE of 8.0 m2 kg–1, and a root mean square error (RMSE of 5.1 m2 kg–1 for the snowpack average SSA. The model, however, is limited under wet conditions due to the single-layer nature of the CLASS model, leading to a single liquid water content value for the whole snowpack. The SSA simulations are of great interest for satellite passive microwave brightness temperature assimilations, snow mass balance retrievals and surface energy balance calculations with associated climate feedbacks.

  12. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    NARCIS (Netherlands)

    van Angelen, J.H.|info:eu-repo/dai/nl/325922470; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Lhermitte, S.; Fettweis, X.; Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van Meijgaard, E.; Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236

    2012-01-01

    We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover,

  13. Challenges and opportunities in land surface modelling of savanna ecosystems

    Science.gov (United States)

    Whitley, Rhys; Beringer, Jason; Hutley, Lindsay B.; Abramowitz, Gabriel; De Kauwe, Martin G.; Evans, Bradley; Haverd, Vanessa; Li, Longhui; Moore, Caitlin; Ryu, Youngryel; Scheiter, Simon; Schymanski, Stanislaus J.; Smith, Benjamin; Wang, Ying-Ping; Williams, Mathew; Yu, Qiang

    2017-10-01

    The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs), which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not) represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model benchmarking and

  14. Challenges and opportunities in land surface modelling of savanna ecosystems

    Directory of Open Access Journals (Sweden)

    R. Whitley

    2017-10-01

    Full Text Available The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs, which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model

  15. Canonical surfaces associated with projectors in Grassmannian sigma models

    International Nuclear Information System (INIS)

    Hussin, V.; Yurdusen, I.; Zakrzewski, W. J.

    2010-01-01

    We discuss the construction of higher-dimensional surfaces based on the harmonic maps of S 2 into CP N-1 and other Grassmannians. We show that there are two ways of implementing this procedure - both based on the use of the relevant projectors. We study various properties of such projectors and show that the Gaussian curvature of these surfaces, in general, is not constant. We look in detail at the surfaces corresponding to the Veronese sequence of such maps and show that for all of them this curvature is constant but its value depends on which mapping is used in the construction of the surface.

  16. The Community Surface Dynamics Modeling System: Experiences on Building a Collaborative Modeling Platform

    Science.gov (United States)

    Overeem, I.; Hutton, E.; Kettner, A.; Peckham, S. D.; Syvitski, J. P.

    2012-12-01

    The Community Surface Dynamics Modeling System - CSDMS- develops a software platform with shared and coupled modules for modeling earth surface processes as a community resource. The framework allows prediction of water, sediment and nutrient transport through the landscape and seacape. The underlying paradigm is that the Earth surface we live on is a dynamic system; topography changes with seasons, with landslides and earthquakes, with erosion and deposition. The Earth Surface changes due to storms and floods, and important boundaries, like the coast, are ever-moving features. CSDMS sets out to make better predictions of these changes. Earth surface process modeling bridges the terrestrial, coastal and marine domains and requires understanding of the system over a range of time scales, which inherently needs interdisciplinarity. Members of CSDMS (~830 in July 2012) are largely from academic institutions (˜75%), followed by federal agencies (˜17%), and oil and gas companies (˜5%). Members and governmental bodies meet once annually and rely additionally on web-based information for communication. As an organization that relies on volunteer participation, CSDMS faces challenges to scientific collaboration. Encouraging volunteerism among its members to provide and adapt metadata and model code to be sufficiently standardized for coupling is crucial to building an integrated community modeling system. We here present CSDMS strategies aimed at providing the appropriate technical tools and cyberinfrastructure to support a variety of user types, ranging from advanced to novice modelers. Application of these advances in science is key, both into the educational realm and for managers and decision-makers. We discuss some of the implemented ideas to further organizational transparency and user engagement in small-scale governance, such as advanced trackers and voting systems for model development prioritization through the CSDMS wiki. We analyzed data on community

  17. Land Surface Model (LSM 1.0) for Ecological, Hydrological, Atmospheric Studies

    Data.gov (United States)

    National Aeronautics and Space Administration — The NCAR LSM 1.0 is a land surface model developed to examine biogeophysical and biogeochemical land-atmosphere interactions, especially the effects of land surfaces...

  18. Model of coordination melting of crystals and anisotropy of physical and chemical properties of the surface

    Science.gov (United States)

    Bokarev, Valery P.; Krasnikov, Gennady Ya

    2018-02-01

    Based on the evaluation of the properties of crystals, such as surface energy and its anisotropy, the surface melting temperature, the anisotropy of the work function of the electron, and the anisotropy of adsorption, were shown the advantages of the model of coordination melting (MCM) in calculating the surface properties of crystals. The model of coordination melting makes it possible to calculate with an acceptable accuracy the specific surface energy of the crystals, the anisotropy of the surface energy, the habit of the natural crystals, the temperature of surface melting of the crystal, the anisotropy of the electron work function and the anisotropy of the adhesive properties of single-crystal surfaces. The advantage of our model is the simplicity of evaluating the surface properties of the crystal based on the data given in the reference literature. In this case, there is no need for a complex mathematical tool, which is used in calculations using quantum chemistry or modeling by molecular dynamics.

  19. Impact of improved Greenland ice sheet surface representation in the NASA GISS ModelE2 GCM on simulated surface mass balance and regional climate

    Science.gov (United States)

    Alexander, P. M.; LeGrande, A. N.; Fischer, E.; Tedesco, M.; Kelley, M.; Schmidt, G. A.; Fettweis, X.

    2017-12-01

    Towards achieving coupled simulations between the NASA Goddard Institute for Space Studies (GISS) ModelE2 general circulation model (GCM) and ice sheet models (ISMs), improvements have been made to the representation of the ice sheet surface in ModelE2. These include a sub-grid-scale elevation class scheme, a multi-layer snow model, a time-variable surface albedo scheme, and adjustments to parameterization of sublimation/evaporation. These changes improve the spatial resolution and physical representation of the ice sheet surface such that the surface is represented at a level of detail closer to that of Regional Climate Models (RCMs). We assess the impact of these changes on simulated Greenland Ice Sheet (GrIS) surface mass balance (SMB). We also compare ModelE2 simulations in which winds have been nudged to match the European Center for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis with simulations from the Modèle Atmosphérique Régionale (MAR) RCM forced by the same reanalysis. Adding surface elevation classes results in a much higher spatial resolution representation of the surface necessary for coupling with ISMs, but has a negligible impact on overall SMB. Implementing a variable surface albedo scheme increases melt by 100%, bringing it closer to melt simulated by MAR. Adjustments made to the representation of topography-influenced surface roughness length in ModelE2 reduce a positive bias in evaporation relative to MAR. We also examine the impact of changes to the GrIS surface on regional atmospheric and oceanic climate in coupled ocean-atmosphere simulations with ModelE2, finding a general warming of the Arctic due to a warmer GrIS, and a cooler North Atlantic in scenarios with doubled atmospheric CO2 relative to pre-industrial levels. The substantial influence of changes to the GrIS surface on the oceans and atmosphere highlight the importance of including these processes in the GCM, in view of potential feedbacks between the ice sheet

  20. Simulating carbon exchange using a regional atmospheric model coupled to an advanced land-surface model

    Directory of Open Access Journals (Sweden)

    H. W. Ter Maat

    2010-08-01

    Full Text Available This paper is a case study to investigate what the main controlling factors are that determine atmospheric carbon dioxide content for a region in the centre of The Netherlands. We use the Regional Atmospheric Modelling System (RAMS, coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C, and including also submodels for urban and marine fluxes, which in principle should include the dominant mechanisms and should be able to capture the relevant dynamics of the system. To validate the model, observations are used that were taken during an intensive observational campaign in central Netherlands in summer 2002. These include flux-tower observations and aircraft observations of vertical profiles and spatial fluxes of various variables.

    The simulations performed with the coupled regional model (RAMS-SWAPS-C are in good qualitative agreement with the observations. The station validation of the model demonstrates that the incoming shortwave radiation and surface fluxes of water and CO2 are well simulated. The comparison against aircraft data shows that the regional meteorology (i.e. wind, temperature is captured well by the model. Comparing spatially explicitly simulated fluxes with aircraft observed fluxes we conclude that in general latent heat fluxes are underestimated by the model compared to the observations but that the latter exhibit large variability within all flights. Sensitivity experiments demonstrate the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same tests also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.

  1. JPL-L4UHblend-NCAMERICA-RTO_SST_An:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  2. JPL-L4UHblend-NCAMERICA-RTO_SST_Td:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  3. JPL-L4UHblend-NCAMERICA-RTO_SST_Tn:1

    Data.gov (United States)

    National Aeronautics and Space Administration — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  4. Models of Fate and Transport of Pollutants in Surface Waters

    Science.gov (United States)

    Okome, Gloria Eloho

    2013-01-01

    There is the need to answer very crucial questions of "what happens to pollutants in surface waters?" This question must be answered to determine the factors controlling fate and transport of chemicals and their evolutionary state in surface waters. Monitoring and experimental methods are used in establishing the environmental states.…

  5. modelling the behaviour of interface surfaces using the finite eleme

    African Journals Online (AJOL)

    user

    Norwell, M.A.. 36. Wingo, etal, Hardware assisted self-collision for rigid and deformable surfaces, Journal of. Tele-operators and Virtual Environments. Dec., 2004. Vol. 13, No 6 pp 681-691. 37. Brian Von Herzen, etal. Geometric Collisions for Time- dependent parametric surfaces. ACM SIGGRAPH Computer Graphics, Aug.,.

  6. Developing a particle tracking surrogate model to improve inversion of ground water - Surface water models

    Science.gov (United States)

    Cousquer, Yohann; Pryet, Alexandre; Atteia, Olivier; Ferré, Ty P. A.; Delbart, Célestine; Valois, Rémi; Dupuy, Alain

    2018-03-01

    The inverse problem of groundwater models is often ill-posed and model parameters are likely to be poorly constrained. Identifiability is improved if diverse data types are used for parameter estimation. However, some models, including detailed solute transport models, are further limited by prohibitive computation times. This often precludes the use of concentration data for parameter estimation, even if those data are available. In the case of surface water-groundwater (SW-GW) models, concentration data can provide SW-GW mixing ratios, which efficiently constrain the estimate of exchange flow, but are rarely used. We propose to reduce computational limits by simulating SW-GW exchange at a sink (well or drain) based on particle tracking under steady state flow conditions. Particle tracking is used to simulate advective transport. A comparison between the particle tracking surrogate model and an advective-dispersive model shows that dispersion can often be neglected when the mixing ratio is computed for a sink, allowing for use of the particle tracking surrogate model. The surrogate model was implemented to solve the inverse problem for a real SW-GW transport problem with heads and concentrations combined in a weighted hybrid objective function. The resulting inversion showed markedly reduced uncertainty in the transmissivity field compared to calibration on head data alone.

  7. Modeling of surface effects in crystalline materials within the framework of gradient crystal plasticity

    Science.gov (United States)

    Peng, Xiang-Long; Husser, Edgar; Huang, Gan-Yun; Bargmann, Swantje

    2018-03-01

    A finite-deformation gradient crystal plasticity theory is developed, which takes into account the interaction between dislocations and surfaces. The model captures both energetic and dissipative effects for surfaces penetrable by dislocations. By taking advantage of the principle of virtual power, the surface microscopic boundary equations are obtained naturally. Surface equations govern surface yielding and hardening. A thin film under shear deformation serves as a benchmark problem for validation of the proposed model. It is found that both energetic and dissipative surface effects significantly affect the plastic behavior.

  8. Free surface modelling with two-fluid model and reduced numerical diffusion of the interface

    International Nuclear Information System (INIS)

    Strubelj, Luka; Tiselj, Izrok

    2008-01-01

    Full text of publication follows: The free surface flows are successfully modelled with one of existing free surface models, such as: level set method, volume of fluid method (with/without surface reconstruction), front tracking, two-fluid model (two momentum equations) with modified interphase force and others. The main disadvantage of two-fluid model used for simulations of free surface flows is numerical diffusion of the interface, which can be significantly reduced using the method presented in this paper. Several techniques for reduction of numerical diffusion of the interface have been implemented in the volume of fluid model and are based on modified numerical schemes for advection of volume fraction near the interface. The same approach could be used also for two-fluid method, but according to our experience more successful reduction of numerical diffusion of the interface can be achieved with conservative level set method. Within the conservative level set method, continuity equation for volume fraction is solved and after that the numerical diffusion of the interface is reduced in such a way that the thickness of the interface is kept constant during the simulation. Reduction of the interface diffusion can be also called interface sharpening. In present paper the two-fluid model with interface sharpening is validated on Rayleigh-Taylor instability. Under assumptions of isothermal and incompressible flow of two immiscible fluids, we simulated a system with the fluid of higher density located above the fluid of smaller density in two dimensions. Due to gravity in the system, fluid with higher density moves below the fluid with smaller density. Initial condition is not a flat interface between the fluids, but a sine wave with small amplitude, which develops into a mushroom-like structure. Mushroom-like structure in simulation of Rayleigh-Taylor instability later develops to small droplets as result of numerical dispersion of interface (interface sharpening

  9. Surface pH controls purple-to-blue transition of bacteriorhodopsin. A theoretical model of purple membrane surface.

    Science.gov (United States)

    Szundi, I; Stoeckenius, W

    1989-08-01

    We have developed a surface model of purple membrane and applied it in an analysis of the purple-to-blue color change of bacteriorhodopsin which is induced by acidification or deionization. The model is based on dissociation and double layer theory and the known membrane structure. We calculated surface pH, ion concentrations, charge density, and potential as a function of bulk pH and concentration of mono- and divalent cations. At low salt concentrations, the surface pH is significantly lower than the bulk pH and it becomes independent of bulk pH in the deionized membrane suspension. Using an experimental acid titration curve for neutral, lipid-depleted membrane, we converted surface pH into absorption values. The calculated bacteriohodopsin color changes for acidification of purple, and titrations of deionized blue membrane with cations or base agree well with experimental results. No chemical binding is required to reproduce the experimental curves. Surface charge and potential changes in acid, base and cation titrations are calculated and their relation to the color change is discussed. Consistent with structural data, 10 primary phosphate and two basic surface groups per bacteriorhodopsin are sufficient to obtain good agreement between all calculated and experimental curves. The results provide a theoretical basis for our earlier conclusion that the purple-to-blue transition must be attributed to surface phenomena and not to cation binding at specific sites in the protein.

  10. On a discrete version of the CP 1 sigma model and surfaces immersed in R3

    International Nuclear Information System (INIS)

    Grundland, A M; Levi, D; Martina, L

    2003-01-01

    We present a discretization of the CP 1 sigma model. We show that the discrete CP 1 sigma model is described by a nonlinear partial second-order difference equation with rational nonlinearity. To derive discrete surfaces immersed in three-dimensional Euclidean space a 'complex' lattice is introduced. The so-obtained surfaces are characterized in terms of the quadrilateral cross-ratio of four surface points. In this way we prove that all surfaces associated with the discrete CP 1 sigma model are of constant mean curvature. An explicit example of such discrete surfaces is constructed

  11. Calibration of a distributed hydrology and land surface model using energy flux measurements

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl; Refsgaard, Jens Christian; Jensen, Karsten H.

    2016-01-01

    In this study we develop and test a calibration approach on a spatially distributed groundwater-surface water catchment model (MIKE SHE) coupled to a land surface model component with particular focus on the water and energy fluxes. The model is calibrated against time series of eddy flux measure...

  12. Constant curvature surfaces of the supersymmetric ℂP{sup N−1} sigma model

    Energy Technology Data Exchange (ETDEWEB)

    Delisle, L., E-mail: delisle@dms.umontreal.ca [Département de Mathématiques et de Statistique, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7 (Canada); Hussin, V., E-mail: hussin@dms.umontreal.ca [Département de Mathématiques et de Statistique, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7 (Canada); Centre de Recherches Mathématiques, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7 (Canada); Yurduşen, İ., E-mail: yurdusen@hacettepe.edu.tr [Department of Mathematics, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Zakrzewski, W. J., E-mail: w.j.zakrzewski@durham.ac.uk [Department of Mathematical Sciences, University of Durham, Durham DH1 3LE,United Kingdom (United Kingdom)

    2015-02-15

    Constant curvature surfaces are constructed from the finite action solutions of the supersymmetric ℂP{sup N−1} sigma model. It is shown that there is a unique holomorphic solution which leads to constant curvature surfaces: the generalized Veronese curve. We give a general criterion to construct non-holomorphic solutions of the model. We extend our analysis to general supersymmetric Grassmannian models.

  13. Inverse modeling of hydrologic parameters using surface flux and runoff observations in the Community Land Model

    Science.gov (United States)

    Sun, Y.; Hou, Z.; Huang, M.; Tian, F.; Leung, L. Ruby

    2013-12-01

    This study demonstrates the possibility of inverting hydrologic parameters using surface flux and runoff observations in version 4 of the Community Land Model (CLM4). Previous studies showed that surface flux and runoff calculations are sensitive to major hydrologic parameters in CLM4 over different watersheds, and illustrated the necessity and possibility of parameter calibration. Both deterministic least-square fitting and stochastic Markov-chain Monte Carlo (MCMC)-Bayesian inversion approaches are evaluated by applying them to CLM4 at selected sites with different climate and soil conditions. The unknowns to be estimated include surface and subsurface runoff generation parameters and vadose zone soil water parameters. We find that using model parameters calibrated by the sampling-based stochastic inversion approaches provides significant improvements in the model simulations compared to using default CLM4 parameter values, and that as more information comes in, the predictive intervals (ranges of posterior distributions) of the calibrated parameters become narrower. In general, parameters that are identified to be significant through sensitivity analyses and statistical tests are better calibrated than those with weak or nonlinear impacts on flux or runoff observations. Temporal resolution of observations has larger impacts on the results of inverse modeling using heat flux data than runoff data. Soil and vegetation cover have important impacts on parameter sensitivities, leading to different patterns of posterior distributions of parameters at different sites. Overall, the MCMC-Bayesian inversion approach effectively and reliably improves the simulation of CLM under different climates and environmental conditions. Bayesian model averaging of the posterior estimates with different reference acceptance probabilities can smooth the posterior distribution and provide more reliable parameter estimates, but at the expense of wider uncertainty bounds.

  14. Comparison of Response Surface and Kriging Models in the Multidisciplinary Design of an Aerospike Nozzle

    Science.gov (United States)

    Simpson, Timothy W.

    1998-01-01

    The use of response surface models and kriging models are compared for approximating non-random, deterministic computer analyses. After discussing the traditional response surface approach for constructing polynomial models for approximation, kriging is presented as an alternative statistical-based approximation method for the design and analysis of computer experiments. Both approximation methods are applied to the multidisciplinary design and analysis of an aerospike nozzle which consists of a computational fluid dynamics model and a finite element analysis model. Error analysis of the response surface and kriging models is performed along with a graphical comparison of the approximations. Four optimization problems are formulated and solved using both approximation models. While neither approximation technique consistently outperforms the other in this example, the kriging models using only a constant for the underlying global model and a Gaussian correlation function perform as well as the second order polynomial response surface models.

  15. Modelling free surface flows with smoothed particle hydrodynamics

    Directory of Open Access Journals (Sweden)

    L.Di G.Sigalotti

    2006-01-01

    Full Text Available In this paper the method of Smoothed Particle Hydrodynamics (SPH is extended to include an adaptive density kernel estimation (ADKE procedure. It is shown that for a van der Waals (vdW fluid, this method can be used to deal with free-surface phenomena without difficulties. In particular, arbitrary moving boundaries can be easily handled because surface tension is effectively simulated by the cohesive pressure forces. Moreover, the ADKE method is seen to increase both the accuracy and stability of SPH since it allows the width of the kernel interpolant to vary locally in a way that only the minimum necessary smoothing is applied at and near free surfaces and sharp fluid-fluid interfaces. The method is robust and easy to implement. Examples of its resolving power are given for both the formation of a circular liquid drop under surface tension and the nonlinear oscillation of excited drops.

  16. Microscopic Analysis and Modeling of Airport Surface Sequencing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The complexity and interdependence of operations on the airport surface motivate the need for a comprehensive and detailed, yet flexible and validated analysis and...

  17. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES

    Science.gov (United States)

    The interactions between agrochemicals and organo-mineral surfaces were studied using molecular mechanical conformational calculations and molecular dynamics simulations. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), 2,4-D (1, 2-dichlorophenoxyacetic acid), and DD...

  18. Triangle geometry processing for surface modeling and cartesian grid generation

    Science.gov (United States)

    Aftosmis, Michael J [San Mateo, CA; Melton, John E [Hollister, CA; Berger, Marsha J [New York, NY

    2002-09-03

    Cartesian mesh generation is accomplished for component based geometries, by intersecting components subject to mesh generation to extract wetted surfaces with a geometry engine using adaptive precision arithmetic in a system which automatically breaks ties with respect to geometric degeneracies. During volume mesh generation, intersected surface triangulations are received to enable mesh generation with cell division of an initially coarse grid. The hexagonal cells are resolved, preserving the ability to directionally divide cells which are locally well aligned.

  19. Kinetics of conformational changes of fibronectin adsorbed onto model surfaces.

    Science.gov (United States)

    Baujard-Lamotte, L; Noinville, S; Goubard, F; Marque, P; Pauthe, E

    2008-05-01

    Fibronectin (FN), a large glycoprotein found in body fluids and in the extracellular matrix, plays a key role in numerous cellular behaviours. We investigate FN adsorption onto hydrophilic bare silica and hydrophobic polystyrene (PS) surfaces using Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) in aqueous medium. Adsorption kinetics using different bulk concentrations of FN were followed for 2h and the surface density of adsorbed FN and its time-dependent conformational changes were determined. When adsorption occurs onto the hydrophilic surface, FN molecules keep their native conformation independent of the adsorption conditions, but the amount of adsorbed FN increases with time and the bulk concentration. Although the protein surface density is the same on the hydrophobic PS surface, this has a strong impact on the average conformation of the adsorbed FN layer. Indeed, interfacial hydration changes induced by adsorption onto the hydrophobic surface lead to a decrease in unhydrated beta-sheet content and cause an increase in hydrated beta-strand and hydrated random domain content of adsorbed FN. This conformational change is mainly dependent on the bulk concentration. Indeed, at low bulk concentrations, the secondary structures of adsorbed FN molecules undergo strong unfolding, allowing an extended and hydrated conformation of the protein. At high bulk concentrations, the molecular packing reduces the unfolding of the stereoregular structures of the FN molecules, preventing stronger spreading of the protein.

  20. Modeling Surface Climate in US Cities Using Simple Biosphere Model Sib2

    Science.gov (United States)

    Zhang, Ping; Bounoua, Lahouari; Thome, Kurtis; Wolfe, Robert; Imhoff, Marc

    2015-01-01

    We combine Landsat- and the Moderate Resolution Imaging Spectroradiometer (MODIS)-based products in the Simple Biosphere model (SiB2) to assess the effects of urbanized land on the continental US (CONUS) surface climate. Using National Land Cover Database (NLCD) Impervious Surface Area (ISA), we define more than 300 urban settlements and their surrounding suburban and rural areas over the CONUS. The SiB2 modeled Gross Primary Production (GPP) over the CONUS of 7.10 PgC (1 PgC= 10(exp 15) grams of Carbon) is comparable to the MODIS improved GPP of 6.29 PgC. At state level, SiB2 GPP is highly correlated with MODIS GPP with a correlation coefficient of 0.94. An increasing horizontal GPP gradient is shown from the urban out to the rural area, with, on average, rural areas fixing 30% more GPP than urbans. Cities built in forested biomes have stronger UHI magnitude than those built in short vegetation with low biomass. Mediterranean climate cities have a stronger UHI in wet season than dry season. Our results also show that for urban areas built within forests, 39% of the precipitation is discharged as surface runoff during summer versus 23% in rural areas.

  1. A COUPLED LAND-SURFACE AND DRY DEPOSITION MODEL AND COMPARISON TO FIELD MEASUREMENTS OF SURFACE HEAT, MOISTURE, AND OZONE FLUXES

    Science.gov (United States)

    We have developed a coupled land-surface and dry deposition model for realistic treatment of surface fluxes of heat, moisture, and chemical dry deposition within a comprehensive air quality modeling system. A new land-surface model (LSM) with explicit treatment of soil moisture...

  2. An integrated modelling framework for regulated river systems in Land Surface Hydrological Models

    Science.gov (United States)

    Rehan Anis, Muhammad; razavi, Saman; Wheater, Howard

    2017-04-01

    Many of the large river systems around the world are highly regulated with numerous physical flow control and storage structures as well as a range of water abstraction rules and regulations. Most existing Land Surface Models (LSM) do not represent the modifications to the hydrological regimes introduced by water management (reservoirs, irrigation diversions, etc.). The interactions between natural hydrological processes and changes in water and energy fluxes and storage due to human interventions are important to the understanding of how these systems may respond to climate change amongst other drivers for change as well as to the assessment of their feedbacks to the climate system at regional and global scales. This study presents an integrated modelling approach to include human interventions within natural hydrological systems using a fully coupled modelling platform. The Bow River Basin in Alberta (26,200 km2), one of the most managed Canadian rivers, is used to demonstrate the approach. We have dynamically linked the MESH modelling system, which embeds the Canadian Land Surface Scheme (CLASS), with the MODSIM-DSS water management modelling tool. MESH models the natural hydrology while MODSIM optimizes the reservoir operation of 4 simulated reservoirs to satisfy demands within the study basin. MESH was calibrated for the catchments upstream the reservoirs and gave good performance (NSE = 0.81) while BIAS was only 2.3% at the catchment outlet. Without coupling with MODSIM (i.e. no regulation), simulated hydrographs at the catchment outlet were in complete disagreement with observations (NSE = 0.28). The coupled model simulated the optimization introduced by the operation of the multi-reservoir system in the Bow river basin and shows excellent agreement between observed and simulated hourly flows (NSE = 0.98). Irrigation demands are fully satisfied during summer, however, there are some shortages in winter demand from industries, which can be rectified by

  3. Comparison of Response Surface and Kriging Models for Multidisciplinary Design Optimization

    Science.gov (United States)

    Simpson, Timothy W.; Korte, John J.; Mauery, Timothy M.; Mistree, Farrokh

    1998-01-01

    In this paper, we compare and contrast the use of second-order response surface models and kriging models for approximating non-random, deterministic computer analyses. After reviewing the response surface method for constructing polynomial approximations, kriging is presented as an alternative approximation method for the design and analysis of computer experiments. Both methods are applied to the multidisciplinary design of an aerospike nozzle which consists of a computational fluid dynamics model and a finite-element model. Error analysis of the response surface and kriging models is performed along with a graphical comparison of the approximations, and four optimization problems m formulated and solved using both sets of approximation models. The second-order response surface models and kriging models-using a constant underlying global model and a Gaussian correlation function-yield comparable results.

  4. Spatial and temporal patterns of land surface fluxes from remotely sensed surface temperatures within an uncertainty modelling framework

    Directory of Open Access Journals (Sweden)

    M. F. McCabe

    2005-01-01

    Full Text Available Characterising the development of evapotranspiration through time is a difficult task, particularly when utilising remote sensing data, because retrieved information is often spatially dense, but temporally sparse. Techniques to expand these essentially instantaneous measures are not only limited, they are restricted by the general paucity of information describing the spatial distribution and temporal evolution of evaporative patterns. In a novel approach, temporal changes in land surface temperatures, derived from NOAA-AVHRR imagery and a generalised split-window algorithm, are used as a calibration variable in a simple land surface scheme (TOPUP and combined within the Generalised Likelihood Uncertainty Estimation (GLUE methodology to provide estimates of areal evapotranspiration at the pixel scale. Such an approach offers an innovative means of transcending the patch or landscape scale of SVAT type models, to spatially distributed estimates of model output. The resulting spatial and temporal patterns of land surface fluxes and surface resistance are used to more fully understand the hydro-ecological trends observed across a study catchment in eastern Australia. The modelling approach is assessed by comparing predicted cumulative evapotranspiration values with surface fluxes determined from Bowen ratio systems and using auxiliary information such as in-situ soil moisture measurements and depth to groundwater to corroborate observed responses.

  5. CHANDRA OBSERVATIONS OF COMETS C/2012 S1 (ISON) AND C/2011 L4 (PanSTARRS)

    Energy Technology Data Exchange (ETDEWEB)

    Snios, Bradford; Kharchenko, Vasili [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Lisse, Carey M. [Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Wolk, Scott J. [Chandra X-Ray Observatory Center, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Dennerl, Konrad [Max-Planck-Institut für extraterrestrische Physik, D-85748 Garching (Germany); Combi, Michael R. [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-02-20

    We present our results on the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer (ACIS) observations of the bright Oort Cloud comets C/2012 S1 (ISON) and C/2011 L4 (PanSTARRS). ISON was observed between 2013 October 31–November 06 during variable speed solar wind (SW), and PanSTARRS was observed between 2013 April 17–23 during fast SW. ISON produced an extended parabolic X-ray morphology consistent with a collisionally thick coma, while PanSTARRS demonstrated only a diffuse X-ray-emitting region. We consider these emissions to be from charge exchange (CX) and model each comet's emission spectrum from first principles accordingly. Our model agrees with the observational spectra and also generates composition ratios for heavy, highly charged SW ions interacting with the cometary atmosphere. We compare our derived SW ion compositions to observational data and find a strong agreement between them. These results further demonstrate the utility of CX emissions as a remote diagnostics tool of both astrophysical plasma interaction and SW composition. In addition, we observe potential soft X-ray emissions via ACIS around 0.2 keV from both comets that are correlated in intensity to the hard X-ray emissions between 0.4–1.0 keV. We fit our CX model to these emissions, but our lack of a unique solution at low energies makes it impossible to conclude if they are cometary CX in origin. Finally, we discuss probable emission mechanism sources for the soft X-rays and explore new opportunities these findings present in understanding cometary emission processes via Chandra.

  6. The influence of the solar radiation model on the calcutated solar radiation from a horizontal surface to a tilted surface

    DEFF Research Database (Denmark)

    Andersen, Elsa; Lund, Hans; Furbo, Simon

    2004-01-01

    in the calculation. The weather data are measured at the solar radiation measurement station, SMS at the Department of Civil Engineering at the Technical University of Denmark. In this study the weather data are combined with solar collector calculations based on solar collector test carried out at Solar Energy...... Center, SEC, Denmark. With measured solar radiation on horizontal and the different solar radiation processing models the total radiation is calculated on differently tilted and oriented surfaces and compared with the measured solar radiation on the different surfaces. Further, the impact on the yearly......Measured solar radiation data are most commonly available as total solar radiation on a horizontal surface. When using solar radiation measured on horizontal to calculate the solar radiation on tilted surfaces and thereby the thermal performance of different applications such as buildings and solar...

  7. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    Science.gov (United States)

    Giresse Tetsassi Feugmo, Conrard; Champagne, Benoît; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J.; Liégeois, Vincent

    2012-03-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement.

  8. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    International Nuclear Information System (INIS)

    Tetsassi Feugmo, Conrard Giresse; Champagne, Benoît; Liégeois, Vincent; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J

    2012-01-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement. (paper)

  9. Modeling of aerodynamic Space-to-Surface flight with optimal trajectory for targeting

    OpenAIRE

    Gornev, Serge

    2003-01-01

    Modeling has been created for a Space-to-Surface system defined for an optimal trajectory for targeting in terminal phase. The modeling includes models for simulation atmosphere, speed of sound, aerodynamic flight and navigation by an infrared system. The modeling simulation includes statistical analysis of the modeling results.

  10. Mathematical Modeling of Aerodynamic Space -to - Surface Flight with Trajectory for Avoid Intercepting Process

    OpenAIRE

    Gornev, Serge

    2006-01-01

    Modeling has been created for a Space-to-Surface system defined for an optimal trajectory for targeting in terminal phase with avoids an intercepting process. The modeling includes models for simulation atmosphere, speed of sound, aerodynamic flight and navigation by an infrared system. The modeling and simulation includes statistical analysis of the modeling results.

  11. Applying horizontal diffusion on pressure surface to mesoscale models on terrain-following coordinates

    Science.gov (United States)

    Hann-Ming Henry Juang; Ching-Teng Lee; Yongxin Zhang; Yucheng Song; Ming-Chin Wu; Yi-Leng Chen; Kevin Kodama; Shyh-Chin Chen

    2005-01-01

    The National Centers for Environmental Prediction regional spectral model and mesoscale spectral model (NCEP RSM/MSM) use a spectral computation on perturbation. The perturbation is defined as a deviation between RSM/MSM forecast value and their outer model or analysis value on model sigma-coordinate surfaces. The horizontal diffusion used in the models applies...

  12. Modeling of surface myoelectric signals--Part II: Model-based signal interpretation.

    Science.gov (United States)

    Merletti, R; Roy, S H; Kupa, E; Roatta, S; Granata, A

    1999-07-01

    Experimental electromyogram (EMG) data from the human biceps brachii were simulated using the model described in [10] of this work. A multichannel linear electrode array, spanning the length of the biceps, was used to detect monopolar and bipolar signals, from which double differential signals were computed, during either voluntary or electrically elicited isometric contractions. For relatively low-level voluntary contractions (10%-30% of maximum force) individual firings of three to four-different motor units were identified and their waveforms were closely approximated by the model. Motor unit parameters such as depth, size, fiber orientation and length, location of innervation and tendonous zones, propagation velocity, and source width were estimated using the model. Two applications of the model are described. The first analyzes the effects of electrode rotation with respect to the muscle fiber direction and shows the possibility of conduction velocity (CV) over- and under-estimation. The second focuses on the myoelectric manifestations of fatigue during a sustained electrically elicited contraction and the interrelationship between muscle fiber CV, spectral and amplitude variables, and the length of the depolarization zone. It is concluded that a) surface EMG detection using an electrode array, when combined with a model of signal propagation, provides a useful method for understanding the physiological and anatomical determinants of EMG waveform characteristics and b) the model provides a way for the interpretation of fatigue plots.

  13. A statistical model for the wettability of surfaces with heterogeneous pore geometries

    Science.gov (United States)

    Brockway, Lance; Taylor, Hayden

    2016-10-01

    We describe a new approach to modeling the wetting behavior of micro- and nano-textured surfaces with varying degrees of geometrical heterogeneity. Surfaces are modeled as pore arrays with a Gaussian distribution of sidewall reentrant angles and a characteristic wall roughness. Unlike conventional wettability models, our model considers the fraction of a surface’s pores that are filled at any time, allowing us to capture more subtle dependences of a liquid’s apparent contact angle on its surface tension. The model has four fitting parameters and is calibrated for a particular surface by measuring the apparent contact angles between the surface and at least four probe liquids. We have calibrated the model for three heterogeneous nanoporous surfaces that we have fabricated: a hydrothermally grown zinc oxide, a film of polyvinylidene fluoride (PVDF) microspheres formed by spinodal decomposition, and a polytetrafluoroethylene (PTFE) film with pores defined by sacrificial polystyrene microspheres. These three surfaces show markedly different dependences of a liquid’s apparent contact angle on the liquid’s surface tension, and the results can be explained by considering geometric variability. The highly variable PTFE pores yield the most gradual variation of apparent contact angle with probe liquid surface tension. The PVDF microspheres are more regular in diameter and, although connected in an irregular manner, result in a much sharper transition from non-wetting to wetting behavior as surface tension reduces. We also demonstrate, by terminating porous zinc oxide with three alternative hydrophobic molecules, that a single geometrical model can capture a structure’s wetting behavior for multiple surface chemistries and liquids. Finally, we contrast our results with those from a highly regular, lithographically-produced structure which shows an extremely sharp dependence of wettability on surface tension. This new model could be valuable in designing and

  14. Random phase mask as a model of a rough surface

    International Nuclear Information System (INIS)

    Svitasheva, S.N.

    2011-01-01

    Artificial roughness was created on sample surfaces by etching through a two-dimensional orthogonal grating with a stochastic distribution of square 'defects' of size. 'Defects' depth was varied from 0.02 μm up to 1.005 μm. The experimental dependences of the scattering of polarized light were studied on four types of surface roughness for two materials: quartz and aluminum. The defect sizes of the random phase mask were 25 x 25 μm and 2.5 x 2.5 μm. The impacts of the sizes and density of artificial defects of rough surfaces on the polarization of reflected light were investigated by multiple-angle-of-incidence (MAI) ellipsometry at a wavelength of 0.63 μm.

  15. An analytical model for force prediction in ball nose micro milling of inclined surfaces

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2010-01-01

    Ball nose micro milling is a key process for the generation of free form surfaces and inclined surfaces often present in mould inserts for micro replication. This paper presents a new cutting force model for ball nose micro milling that is capable of taking into account the effect of the edge rad...... radius and the effect of the surface topography due to the previous milling passes. The model is completely analytical can be applied to ball end micro milling of slanted surfaces for any value of the surface inclination angle relative to the tool axis....

  16. Three cases of L4-5 Baastrup's disease due to L5-S1 spondylolytic spondylolisthesis.

    Science.gov (United States)

    Seo, Jin-Suk; Lee, Sang-Ho; Keum, Han Joong; Eun, Sang Soo

    2017-05-01

    Baastrup's disease is characterized by degeneration of spinous processes and interspinous soft tissue, which may cause spinal stenosis. Purpose of this article is to report the possible new cause of Baastrup's disease and result of surgical treatments. Authors treated three cases of Baastrup's disease on L4-L5 with L5-S1 spondylolytic listhesis. Conservative treatment did not relieve the pain; therefore, surgical treatments were planned according to each specific disease condition. In one case, anterior lumbar interbody fusion of L5-S1 was performed, and after surgery, the size of epidural cyst on L4-L5 was decreased. L4-L5 bilateral laminectomy was performed to directly decompress posterior epidural cyst in a case with stable L5-S1 spondylolytic listhesis. In last case, facet joints and spinous process were removed by L5-S1 posterior lumbar interbody fusion (PLIF) surgery. After the surgery, patients' back and leg pain was improved and postoperative MRI revealed successful decompression of the spinal canal. Improvement in back and leg symptoms was noted at 12-month follow-up. Baastrup's disease at the L4-L5 level may have developed from the instability caused by L5-S1 spondylolytic spondylolisthesis. Viable treatment options include the fusion of L5-S1 or a laminectomy at the L4-L5 level.

  17. Soil surface roughness modeling: limit of global characterization in remote sensing

    Science.gov (United States)

    Chimi-Chiadjeu, O.; Vannier, E.; Dusséaux, R.; Taconet, O.

    2013-10-01

    Many scientists use a global characterization of bare soil surface random roughness. Surface roughness is often characterized by statistical parameters deduced from its autocorrelation function. Assuming an autocorrelation model and a Gaussian height distribution, some authors have developed algorithms for numerical generation of soil surfaces that have the same statistical properties. This approach is widespread and does not take into account morphological aspects of the soil surface micro-topography. Now a detail surface roughness analysis reveals that the micro-topography is structured by holes, aggregates and clods. In the present study, we clearly show that when describing surface roughness as a whole, some information related to morphological aspects is lost. Two Digital Elevation Model (DEM) of a same natural seedbed surface were recorded by stereo photogrammetry. After estimating global parameters of these natural surfaces, we generated numerical surfaces of the same average characteristics by linear filtering. Big aggregates and clods were then captured by a contour-based approach. We show that the two-dimensional autocorrelation functions of generated surfaces and of the two agricultural surfaces are close together. Nevertheless, the number and shape of segmented object contours change from generated surfaces to the natural surfaces. Generated surfaces show fewer and bigger segmented objects than in the natural case. Moreover, the shape of some segmented objects is unrealistic in comparison to real clods, which have to be convex and of low circularity.

  18. Recovery after fracture dislocation of L3/L4 ASIA B: Case report

    Directory of Open Access Journals (Sweden)

    Gustavo Caldera

    2016-02-01

    Full Text Available In fracture dislocations of the lumbar region, two anatomical facts can help preserve neurological damage in patients, when compared with trauma in the cervical or thoracic region. Firstly, the spinal cord in adults extends only to the lower edge of the first lumbar vertebra, and secondly, the large vertebral space in this region gives ample space for the roots of the cauda equine. As a result, the nerve injury may be minimal, because the nerve roots in this region are accommodated in a larger area, with less content and space. This study presents the case of a 48-year-old male, a construction worker, who suffered a fall from a height of approximately 15 meters, directly hitting the lumbar region against a beam, and presenting pain and inability to move the legs. The patient was brought to the emergency room 1 hour after the accident, clinically assessed, submitted to x-rays and a CT scan, and diagnosed as having an ASIA B L3-L4 fracture dislocation. Three hours after the accident, reduction was performed via posterior transpedicular fixation. One week later, an anterior approach was performed. The patient progressed to ASIA C 24 hours after the first surgery. Three months later, the patient was functional with ASIA D and good sphincter control. The author's purpose is to show the results obtained by an intervention in the initial hours of the trauma, which helped promote the evolution from a nonfunctional injury to a functional one, with near-total recovery. Keywords: Spine fracture, Recovery, Neurological deficit, Asia scale, Dislocation

  19. Modelled long term trends of surface ozone over South Africa

    CSIR Research Space (South Africa)

    Naidoo, M

    2011-10-01

    Full Text Available timescale seeks to provide a spatially comprehensive view of trends while also creating a baseline for comparisons with future projections of air quality through the forcing of air quality models with modelled predicted long term meteorology. Previous...

  20. A Monte Carlo reflectance model for soil surfaces with three-dimensional structure

    Science.gov (United States)

    Cooper, K. D.; Smith, J. A.

    1985-01-01

    A Monte Carlo soil reflectance model has been developed to study the effect of macroscopic surface irregularities larger than the wavelength of incident flux. The model treats incoherent multiple scattering from Lambertian facets distributed on a periodic surface. Resulting bidirectional reflectance distribution functions are non-Lambertian and compare well with experimental trends reported in the literature. Examples showing the coupling of the Monte Carlo soil model to an adding bidirectional canopy of reflectance model are also given.

  1. General Models for Assessing Hazards Aircraft Pose to Surface Facilities

    International Nuclear Information System (INIS)

    Ragan, G.E.

    2002-01-01

    This paper derives formulas for estimating the frequency of accidental aircraft crashes into surface facilities. Objects unintentionally dropped from aircraft are also considered. The approach allows the facility to be well within the flight area; inside the flight area, but close to the edge; or completely outside the flight area

  2. Empirical model for estimating the surface roughness of machined ...

    African Journals Online (AJOL)

    The increasing importance of turning operations is gaining new dimensions in the present industrial age, in which the growing competition calls for all the efforts to be directed towards the economical manufacture of machined parts as well as surface finish is one of the most critical quality measure in mechanical products.

  3. Response Surface Model Building Using Orthogonal Arrays for Computer Experiments

    Science.gov (United States)

    Unal, Resit; Braun, Robert D.; Moore, Arlene A.; Lepsch, Roger A.

    1997-01-01

    This study investigates response surface methods for computer experiments and discusses some of the approaches available. Orthogonal arrays constructed for computer experiments are studied and an example application to a technology selection and optimization study for a reusable launch vehicle is presented.

  4. Trends in hydrodesulfurization catalysis based on realistic surface models

    DEFF Research Database (Denmark)

    Moses, P.G.; Grabow, L.C.; Fernandez Sanchez, Eva

    2014-01-01

    Trends in hydrodesulfurization (HDS) activity are investigated on the basis of surface properties calculated by density functional theory for a series of HDS catalysts. It is shown that approximately linear correlations exist between HS group binding energies and activation barriers of key elemen...

  5. Modeling surface aerodynamic temperature in a semiarid advective environment

    Science.gov (United States)

    In mapping evapotranspiration (ET), latent heat flux (LE) can be spatially estimated as an energy balance (EB) residual for land surfaces using remote sensing inputs. The EB equation requires the estimation of net radiation (Rn), soil heat flux (G), and sensible heat flux (H). Rn and G can be estima...

  6. Screening model for nanowire surface-charge sensors in liquid

    DEFF Research Database (Denmark)

    Sørensen, Martin Hedegård; Mortensen, Asger; Brandbyge, Mads

    2007-01-01

    The conductance change of nanowire field-effect transistors is considered a highly sensitive probe for surface charge. However, Debye screening of relevant physiological liquid environments challenge device performance due to competing screening from the ionic liquid and nanowire charge carriers....

  7. Modelling the effects of surface water flood pulses on groundwater

    NARCIS (Netherlands)

    Schot, P.P.; Wassen, M.J.

    2010-01-01

    Flood pulses in wetlands steer ecosystem development directly through surface water processes and indirectly through the effects of the flood pulse on groundwater. Direct effects on ecosystems are exerted by e.g. inundation and deposition of sediments containing nutrients. Indirect effects include

  8. A physically-based model of global freshwater surface temperature

    NARCIS (Netherlands)

    van Beek, L.P.H.; Eikelboom, T.; van Vliet, M.T.H.; Bierkens, M.F.P.

    2012-01-01

    Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through

  9. A physically based model of global freshwater surface temperature

    NARCIS (Netherlands)

    Beek, van L.P.H.; Eikelboom, T.; Vliet, van M.T.H.; Bierkens, M.F.P.

    2012-01-01

    Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through

  10. SEMIC: an efficient surface energy and mass balance model applied to the Greenland ice sheet

    Directory of Open Access Journals (Sweden)

    M. Krapp

    2017-07-01

    Full Text Available We present SEMIC, a Surface Energy and Mass balance model of Intermediate Complexity for snow- and ice-covered surfaces such as the Greenland ice sheet. SEMIC is fast enough for glacial cycle applications, making it a suitable replacement for simpler methods such as the positive degree day (PDD method often used in ice sheet modelling. Our model explicitly calculates the main processes involved in the surface energy and mass balance, while maintaining a simple interface and requiring minimal data input to drive it. In this novel approach, we parameterise diurnal temperature variations in order to more realistically capture the daily thaw–freeze cycles that characterise the ice sheet mass balance. We show how to derive optimal model parameters for SEMIC specifically to reproduce surface characteristics and day-to-day variations similar to the regional climate model MAR (Modèle Atmosphérique Régional, version 2 and its incorporated multilayer snowpack model SISVAT (Soil Ice Snow Vegetation Atmosphere Transfer. A validation test shows that SEMIC simulates future changes in surface temperature and surface mass balance in good agreement with the more sophisticated multilayer snowpack model SISVAT included in MAR. With this paper, we present a physically based surface model to the ice sheet modelling community that is general enough to be used with in situ observations, climate model, or reanalysis data, and that is at the same time computationally fast enough for long-term integrations, such as glacial cycles or future climate change scenarios.

  11. Quantifying watershed surface depression storage: determination and application in a hydrologic model

    Science.gov (United States)

    Joseph K. O. Amoah; Devendra M. Amatya; Soronnadi. Nnaji

    2012-01-01

    Hydrologic models often require correct estimates of surface macro-depressional storage to accurately simulate rainfall–runoff processes. Traditionally, depression storage is determined through model calibration or lumped with soil storage components or on an ad hoc basis. This paper investigates a holistic approach for estimating surface depressional storage capacity...

  12. Surface states of a system of Dirac fermions: A minimal model

    International Nuclear Information System (INIS)

    Volkov, V. A.; Enaldiev, V. V.

    2016-01-01

    A brief survey is given of theoretical works on surface states (SSs) in Dirac materials. Within the formalism of envelope wave functions and boundary conditions for these functions, a minimal model is formulated that analytically describes surface and edge states of various (topological and nontopological) types in several systems with Dirac fermions (DFs). The applicability conditions of this model are discussed.

  13. Description and application of the combined surface and groundwater flow model MOGROW

    NARCIS (Netherlands)

    Querner, E.P.

    1997-01-01

    In the Netherlands shallow groundwater tables prevail in many parts, such that groundwater and surface water are closely interlinked. Thus the use of a combined groundwater and surface water model is necessary to predict the effect of certain measures on a regional scale. Therefore the model MOGROW

  14. Characterization of metal additive manufacturing surfaces using synchrotron X-ray CT and micromechanical modeling

    Science.gov (United States)

    Kantzos, C. A.; Cunningham, R. W.; Tari, V.; Rollett, A. D.

    2017-12-01

    Characterizing complex surface topologies is necessary to understand stress concentrations created by rough surfaces, particularly those made via laser power-bed additive manufacturing (AM). Synchrotron-based X-ray microtomography (μ XCT ) of AM surfaces was shown to provide high resolution detail of surface features and near-surface porosity. Using the CT reconstructions to instantiate a micromechanical model indicated that surface notches and near-surface porosity both act as stress concentrators, while adhered powder carried little to no load. Differences in powder size distribution had no direct effect on the relevant surface features, nor on stress concentrations. Conventional measurements of surface roughness, which are highly influenced by adhered powder, are therefore unlikely to contain the information relevant to damage accumulation and crack initiation.

  15. A Visibility-Aware Model for Pre-Filtering and Rendering Surfaces in Real-Time

    OpenAIRE

    Heitz, Eric; Neyret, Fabrice

    2011-01-01

    We present a multiscale surface appearance representation and a rendering model that accounts for the subpixel visibility distribution. Starting from this model, we propose a method for pre-filtering detailed surfaces and their attributes. Our representation of the filtered attributes takes the correlation with their visibility into account. The masking and shadowing effects lost in geometric filtering of the surface can thus be recovered at rendering. This grants high visual quality of subpi...

  16. A travelling wave model of ripple formation on ion bombarded surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi, E-mail: s.numazawa@hzdr.de; Smith, Roger, E-mail: R.Smith@lboro.ac.uk

    2013-05-15

    We present a mathematical model describing surface modification resulting from atomic motion after ion bombardment. The model considers only the defect production and recovery process induced by the local atom rearrangement and is essentially independent of surface topography changes formed by both sputtering and surface diffusion. A stable analytic, travelling wave solution is presented for a specific incident angle, which agrees with experimental observation excellently.

  17. THE CORRELATION DEPENDENCE OF THE CLINICAL AND MORPHOLOGICAL MANIFESTATIONS AND BIOMECHANICAL PARAMETERS IN PATIENTS WITH DEGENERATIVE SPONDYLOLISTHESIS L4 VERTEBRA

    Directory of Open Access Journals (Sweden)

    A. V. Krut’Ko

    2011-01-01

    Full Text Available The study included 59 operated patients with spondylolisthesis L4 vertebra of I degree. All the patients were held clinical-anamnestic, neurological, radiological, radiopaque and biomechanical studies, MRI, CT, as well as puncture performed provocative tests. Revealed correlation of clinical manifestations of degenerative spondylolisthesis L4 and biomechanical parameters of the shape and orientation of the lumbar spine. The most pronounced clinical and morphological changes detected at the level of spondylolisthesis and adjacent segments in the group with hyperlordosis and excessive tilt angle of the chord forward, which is confirmed by MRI, CT, and carried out a disco-puncture provocative tests. A variety of pathological changes of the lumbar spine at L4 vertebra degenerative spondylolisthesis correlated with the biomechanical parameters violation of the shape and orientation of the spine in the sagittal plane.

  18. REYNOLDS_NCEP_L4_SST_OPT_INTERP_MONTHLY_V2:1

    Data.gov (United States)

    National Aeronautics and Space Administration — Multichannel sea-surface temperatures (MCSST) have been computed from AVHRR radiances operational since 1981. In-situ data is derived from both ship and buoys. Both...

  19. Incorporating Floating Surface Objects into a Fully Dispersive Surface Wave Model

    Science.gov (United States)

    2016-04-19

    Decimation and Interpolation (PDI) Method was dded to NHWAVE by Shi et al. (2015) , who confirmed that the dy- amic pressure can be modeled accurately... cluster Farber located at he University of Delaware. Using 48 cores, it took about 8 h for a imulation of 10 0 0 s. The 10 m water depth was selected to re... decimation and interpolation (PDI) method for a baroclinic non-hydrostatic model. Ocean Mod. 96, 265–279 . 26 M.D. Orzech et al. / Ocean Modelling 102 (2016

  20. Fast, Statistical Model of Surface Roughness for Ion-Solid Interaction Simulations and Efficient Code Coupling

    Science.gov (United States)

    Drobny, Jon; Curreli, Davide; Ruzic, David; Lasa, Ane; Green, David; Canik, John; Younkin, Tim; Blondel, Sophie; Wirth, Brian

    2017-10-01

    Surface roughness greatly impacts material erosion, and thus plays an important role in Plasma-Surface Interactions. Developing strategies for efficiently introducing rough surfaces into ion-solid interaction codes will be an important step towards whole-device modeling of plasma devices and future fusion reactors such as ITER. Fractal TRIDYN (F-TRIDYN) is an upgraded version of the Monte Carlo, BCA program TRIDYN developed for this purpose that includes an explicit fractal model of surface roughness and extended input and output options for file-based code coupling. Code coupling with both plasma and material codes has been achieved and allows for multi-scale, whole-device modeling of plasma experiments. These code coupling results will be presented. F-TRIDYN has been further upgraded with an alternative, statistical model of surface roughness. The statistical model is significantly faster than and compares favorably to the fractal model. Additionally, the statistical model compares well to alternative computational surface roughness models and experiments. Theoretical links between the fractal and statistical models are made, and further connections to experimental measurements of surface roughness are explored. This work was supported by the PSI-SciDAC Project funded by the U.S. Department of Energy through contract DOE-DE-SC0008658.

  1. Studies on surface tension effect for free surface flow around floating models; Futai mokei mawari no jiyu hyomenryu ni oyobosu hyomen choryoku no eikyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)

    1996-12-31

    The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.

  2. Dynamical models for sand ripples beneath surface waves

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Chabanol, M.-L.; v. Hecke, M.

    2001-01-01

    We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass...... transport function, our models predict the existence of a stable band of wave numbers limited by secondary instabilities. Small ripples coarsen in our models and this process leads to a sharply selected final wave number, in agreement with experimental observations....

  3. Modelling of boiler heating surfaces and evaporator circuits

    DEFF Research Database (Denmark)

    Sørensen, K.; Condra, T.; Houbak, Niels

    2002-01-01

    Dynamic models for simulating boiler performance have been developed. Models for the flue gas side and for the evaporator circuit have been developed for the purpose of determining material temperatures and heat transfer from the flue gas side to the water-/steam side in order to simulate...... the circulation in the evaporator circuit. The models have been developed as Differential-Algebraic-Equations (DAE) and MATLAB has been applied for the integration of the models. In general MATLAB has proved to be very stable for the relatively stiff equation systems. Experimental verification is planned...... at a full scale plant equipped with instrumentation to verify heat transfer and circulation in the evaporator circuit....

  4. Modeling the erythemal surface diffuse irradiance fraction for Badajoz, Spain

    Science.gov (United States)

    Sanchez, Guadalupe; Serrano, Antonio; Cancillo, María Luisa

    2017-10-01

    Despite its important role on the human health and numerous biological processes, the diffuse component of the erythemal ultraviolet irradiance (UVER) is scarcely measured at standard radiometric stations and therefore needs to be estimated. This study proposes and compares 10 empirical models to estimate the UVER diffuse fraction. These models are inspired from mathematical expressions originally used to estimate total diffuse fraction, but, in this study, they are applied to the UVER case and tested against experimental measurements. In addition to adapting to the UVER range the various independent variables involved in these models, the total ozone column has been added in order to account for its strong impact on the attenuation of ultraviolet radiation. The proposed models are fitted to experimental measurements and validated against an independent subset. The best-performing model (RAU3) is based on a model proposed by Ruiz-Arias et al. (2010) and shows values of r2 equal to 0.91 and relative root-mean-square error (rRMSE) equal to 6.1 %. The performance achieved by this entirely empirical model is better than those obtained by previous semi-empirical approaches and therefore needs no additional information from other physically based models. This study expands on previous research to the ultraviolet range and provides reliable empirical models to accurately estimate the UVER diffuse fraction.

  5. Surface Modelling of Nanostructured Copper Subjected to Erosion-Corrosion

    Directory of Open Access Journals (Sweden)

    Osama M. Irfan

    2017-04-01

    Full Text Available The last decade has witnessed considerable advancements in nanostructured material synthesis and property characterization. However, there still exists some deficiency in the mechanical and surface property characterization of these materials. In this paper, the erosion corrosion (E-C behavior of nanostructured copper was studied. The nanostructured copper was produced through severe plastic deformation (SPD by applying four passes of equal channel angular pressing (ECAP. The combined effects of the testing time, impact velocity, and concentration of erosive solid particles (i.e., sand concentration on the E-C behavior of nanostructured copper were then examined. Based on a defined domain for the testing time, impact velocity, and sand concentration, E-C tests were performed for numerous combinations of test points via the slurry pot method. The test points were selected using the face-centered center composite design of experiments to enable visualization of the test results through surface plots. The extent of E-C on the test specimens was determined by measuring the mass loss. Polynomial regression and Kriging were used to fit surfaces to the experimental data, which were subsequently used to generate surface plots. The results showed that the E-C of nanostructured copper is best described by a quadratic function of testing time, velocity, and erosive solid particle concentration. The results also revealed that E-C increases with an increasing testing time, impact velocity, and erosive solid particle concentration. In addition, it was observed that the effect of the erosive solid particles on E-C is further intensified by an increased impact velocity.

  6. Improved Modeling and Prediction of Surface Wave Amplitudes

    Science.gov (United States)

    2017-05-31

    data does not license the holder or any other person or corporation; or convey any rights or permission to manufacture, use, or sell any patented... advantages of the membrane surface wave technique are that 1) it is orders of magnitude faster than 3-dimensional finite-difference; and 2) it...0.5 km depth. Although the CMT sources should more accurately reproduce the observed signals from each event, they have two disadvantages : 1) in the

  7. Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential

    Science.gov (United States)

    Tournassat, C.; Tinnacher, R. M.; Grangeon, S.; Davis, J. A.

    2018-01-01

    The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonite edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites ('spillover' effect). A series of U(VI) - Na-montmorillonite batch adsorption experiments was conducted as a function of pH, with variable U(VI), Ca, and dissolved carbonate concentrations. Based on the experimental data, a new type of surface complexation model (SCM) was developed for montmorillonite, that specifically accounts for the spillover effect using the edge surface speciation model by Tournassat et al. (2016a). The SCM allows for a prediction of U(VI) adsorption under varying chemical conditions with a minimum number of fitting parameters, not only for our own experimental results, but also for a number of published data sets. The model agreed well with many of these datasets without introducing a second site type or including the formation of ternary U(VI)-carbonato surface complexes. The model predictions were greatly impacted by utilizing analytical measurements of dissolved inorganic carbon (DIC) concentrations in individual sample solutions rather than assuming solution equilibration with a specific partial pressure of CO2, even when the gas phase was

  8. The interaction of carbon monoxide with model astrophysical surfaces.

    Science.gov (United States)

    Collings, Mark P; Dever, John W; McCoustra, Martin R S

    2014-02-28

    Carbon monoxide (CO) is an important component of the icy mantles that accrete on interstellar dust grains. To develop a better understanding of the physicochemical basis of its infrared spectroscopy, we have studied the interaction of submonolayer coverages of CO with the surface of films of other astrophysically relevant species--(13)CO, carbon dioxide (CO2), ammonia (NH3), methanol (CH3OH) and water (H2O)--under ultrahigh vacuum and cryogenic (10 K) conditions using reflection-absorption infrared spectroscopy (RAIRS). In support of these measurements, we have performed ab initio calculations of gas phase dimer complexes, and made comparisons to experimental results of gas phase and matrix isolated complexes, which are extensively reported in the literature. The interaction of CO can be categorised as occurring via the C atom (C(CO) bonded), the O atom (O(CO) bonded) or in a π-bonded configuration. The C(CO) configuration is characterised by a blue shifted C≡O stretch frequency, and is observed for CO adsorbed on (13)CO, CO2 and H2O surfaces. From the absence of such a feature from the spectra of CO adsorbed on CH3OH it can be concluded that the dangling OH bonds required for this adsorption configuration are not present at the surface of the CH3OH film.

  9. Using subdivision surfaces and adaptive surface simplification algorithms for modeling chemical heterogeneities in geophysical flows

    Science.gov (United States)

    Schmalzl, JöRg; Loddoch, Alexander

    2003-09-01

    We present a new method for investigating the transport of an active chemical component in a convective flow. We apply a three-dimensional front tracking method using a triangular mesh. For the refinement of the mesh we use subdivision surfaces which have been developed over the last decade primarily in the field of computer graphics. We present two different subdivision schemes and discuss their applicability to problems related to fluid dynamics. For adaptive refinement we propose a weight function based on the length of triangle edge and the sum of the angles of the triangle formed with neighboring triangles. In order to remove excess triangles we apply an adaptive surface simplification method based on quadric error metrics. We test these schemes by advecting a blob of passive material in a steady state flow in which the total volume is well preserved over a long time. Since for time-dependent flows the number of triangles may increase exponentially in time we propose the use of a subdivision scheme with diffusive properties in order to remove the small scale features of the chemical field. By doing so we are able to follow the evolution of a heavy chemical component in a vigorously convecting field. This calculation is aimed at the fate of a heavy layer at the Earth's core-mantle boundary. Since the viscosity variation with temperature is of key importance we also present a calculation with a strongly temperature-dependent viscosity.

  10. Transient Thermal Model and Analysis of the Lunar Surface and Regolith for Cryogenic Fluid Storage

    Science.gov (United States)

    Christie, Robert J.; Plachta, David W.; Yasan, Mohammad M.

    2008-01-01

    A transient thermal model of the lunar surface and regolith was developed along with analytical techniques which will be used to evaluate the storage of cryogenic fluids at equatorial and polar landing sites. The model can provide lunar surface and subsurface temperatures as a function of latitude and time throughout the lunar cycle and season. It also accounts for the presence of or lack of the undisturbed fluff layer on the lunar surface. The model was validated with Apollo 15 and Clementine data and shows good agreement with other analytical models.

  11. Finite element modeling of surface subsidence induced by underground coal mining

    International Nuclear Information System (INIS)

    Su, D.W.H.

    1992-01-01

    The ability to predict the effects of longwall mining on topography and surface structures is important for any coal company in making permit applications and anticipating potential mining problems. The sophisticated finite element model described and evaluated in this paper is based upon five years of underground and surface observations and evolutionary development of modeling techniques and attributes. The model provides a very powerful tool to address subsidence and other ground control questions. The model can be used to calculate postmining stress and strain conditions at any horizon between the mine and the ground surface. This holds the promise of assisting in the prediction of mining-related hydrological effects

  12. Implementing surface parameter aggregation rules in the CCM3 global climate model: regional responses at the land surface

    Directory of Open Access Journals (Sweden)

    M. A. Arain

    1999-01-01

    Full Text Available The land-surface parameters required as input to a GCM grid box (typically a few degrees are often set to be those of the dominant vegetation type within the grid box. This paper discusses the use and effect of aggregation rules for specifying effective values of these land cover parameters by taking into account the relative proportion of each land-cover type within each individual grid box. Global land-cover classification data at 1 km resolution were used to define Biosphere Atmosphere Transfer Scheme (BATS specific aggregate (using aggregation rules land-cover parameters. Comparison of the values of the aggregate parameters and those defined using the single dominant vegetation type (default parameters shows significant differences in some regions, particularly in the semi-desert and in forested regions, e.g. the Sahara Desert and the tropical forest of South America. These two different sets of parameters were used as input data for two 10-year simulations of the NCAR CCM3 model coupled to the BATS land-surface scheme. Statistical analyses comparing the results of the two model runs showed that the resulting effects on the land-surface diagnostics are significant only in specific regions. For example, the sensible heat flux in the Sahara Desert calculated for the aggregate parameter run increased due to the marked increase in the minimum stomatal resistance and the decrease in fractional vegetation cover in the aggregate parameters over the default parameters. The modelled global precipitation and surface air temperature fields were compared to observations: there is a general improvement in the performance of the aggregate parameter run over the default parameter run in areas where the differences between the aggregate and default parameter run are significant. However, most of the difference between the modelled and observed fields is attributable to other model deficiencies. It can be concluded that the use of aggregation rules to derive

  13. Surface-bounded growth modeling applied to human mandibles

    DEFF Research Database (Denmark)

    Andresen, Per Rønsholt; Brookstein, F. L.; Conradsen, Knut

    2000-01-01

    automatically using shape features and a new algorithm called geometry-constrained diffusion. The semilandmarks are mapped into Procrustes space. Principal component analysis extracts a one-dimensional subspace, which is used to construct a linear growth model. The worst case mean modeling error in a cross...

  14. Informing groundwater models with near-surface geophysical data

    DEFF Research Database (Denmark)

    Herckenrath, Daan

    CHI-approach was developed, called CHI-P (Parameter), which applies coupling constraints between the geophysical and hydrologic model parameters. A CHI-P was used to estimate hydraulic conductivities and geological layer elevations for a synthetic groundwater model using Time-Domain Electromagnetic...

  15. A tri-objective, dynamic weapon assignment model for surface ...

    African Journals Online (AJOL)

    In this paper, a tri-objective, dynamic weapon assignment model is proposed by modelling the weapon assignment problem as a multi-objective variation of the celebrated vehicle routing problem with time windows. A multi-objective, evolutionary metaheuristic for solving the vehicle routing problem with time windows is ...

  16. Impact of surface waves in a Regional Climate Model

    DEFF Research Database (Denmark)

    Rutgersson, Anna; Sætra, Oyvind; Semedo, Alvaro

    2010-01-01

    A coupled regional atmosphere-wave model system is developed with the purpose of investigating the impact of climate changes on the wave field, as well as feed-back effects of the wave field on the atmospheric parameters. This study focuses on the effects of introducing a two-way atmosphere......-wave coupling on the atmosphere as well as on wave parameters. The model components are the regional climate model RCA, and the third generation wave model WAM. Two different methods are used for the coupling, using the roughness length and only including the effect of growing sea, and using the wave age...... in climate models for a realistic description of processes over sea....

  17. Development of Fractal Dimension and Characteristic Roughness Models for Turned Surface of Carbon Steels

    Science.gov (United States)

    Zuo, Xue; Zhu, Hua; Zhou, Yuankai; Ding, Cong; Sun, Guodong

    2016-08-01

    Relationships between material hardness, turning parameters (spindle speed and feed rate) and surface parameters (surface roughness Ra, fractal dimension D and characteristic roughness τ∗) are studied and modeled using response surface methodology (RSM). The experiments are carried out on a CNC lathe for six carbon steel material AISI 1010, AISI 1020, AISI 1030, AISI 1045, AISI 1050 and AISI 1060. The profile of turned surface and the surface roughness value are measured by a JB-5C profilometer. Based on the profile data, D and τ∗ are computed through the root-mean-square method. The analysis of variance (ANOVA) reveals that spindle speed is the most significant factors affecting Ra, while material hardness is the most dominant parameter affecting τ∗. Material hardness and spindle speed have the same influence on D. Feed rate has less effect on three surface parameters than spindle speed and material hardness. The second-order models of RSM are established for estimating Ra, D and τ∗. The validity of the developed models is approximately 80%. The response surfaces show that a surface with small Ra and large D and τ∗ can be obtained by selecting a high speed and a large hardness material. According to the established models, Ra, D and τ∗ of six carbon steels surfaces can be predicted under cutting conditions studied in this paper. The results have an instructive meaning to estimate the surface quality before turning.

  18. Modelling the growth of Listeria monocytogenes on the surface of smear- or mould-ripened cheese

    Directory of Open Access Journals (Sweden)

    Sol eSchvartzman

    2014-07-01

    Full Text Available Surface-ripened cheeses are matured by means of manual or mechanical technologies posing a risk of cross-contamination, if any cheeses are contaminated with Listeria monocytogenes. In predictive microbiology, primary models are used to describe microbial responses, such as growth rate over time and secondary models explain how those responses change with environmental factors. In this way, primary models were used to assess the growth rate of L. monocytogenes during ripening of the cheeses and the secondary models to test how much the growth rate was affected by either the pH and/or the water activity (aw of the cheeses. The two models combined can be used to predict outcomes. The purpose of these experiments was to test three primary (the modified Gompertz equation, the Baranyi and Roberts model and the Logistic model and three secondary (the Cardinal model, the Ratowski model and the Presser model mathematical models in order to define which combination of models would best predict the growth of L. monocytogenes on the surface of artificially contaminated surface-ripened cheeses. Growth on the surface of the cheese was assessed and modelled. The primary models were firstly fitted to the data and the effects of pH and aw on the growth rate (μmax were incorporated and assessed one by one with the secondary models. The Logistic primary model by itself did not show a better fit of the data among the other primary models tested, but the inclusion of the Cardinal secondary model improved the final fit. The aw was not related to the growth of Listeria. This study suggests that surface-ripened cheese should be separately regulated within EU microbiological food legislation and results expressed as counts per surface area rather than per gram.

  19. Filling the voids in the SRTM elevation model — A TIN-based delta surface approach

    Science.gov (United States)

    Luedeling, Eike; Siebert, Stefan; Buerkert, Andreas

    The Digital Elevation Model (DEM) derived from NASA's Shuttle Radar Topography Mission is the most accurate near-global elevation model that is publicly available. However, it contains many data voids, mostly in mountainous terrain. This problem is particularly severe in the rugged Oman Mountains. This study presents a method to fill these voids using a fill surface derived from Russian military maps. For this we developed a new method, which is based on Triangular Irregular Networks (TINs). For each void, we extracted points around the edge of the void from the SRTM DEM and the fill surface. TINs were calculated from these points and converted to a base surface for each dataset. The fill base surface was subtracted from the fill surface, and the result added to the SRTM base surface. The fill surface could then seamlessly be merged with the SRTM DEM. For validation, we compared the resulting DEM to the original SRTM surface, to the fill DEM and to a surface calculated by the International Center for Tropical Agriculture (CIAT) from the SRTM data. We calculated the differences between measured GPS positions and the respective surfaces for 187,500 points throughout the mountain range (ΔGPS). Comparison of the means and standard deviations of these values showed that for the void areas, the fill surface was most accurate, with a standard deviation of the ΔGPS from the mean ΔGPS of 69 m, and only little accuracy was lost by merging it to the SRTM surface (standard deviation of 76 m). The CIAT model was much less accurate in these areas (standard deviation of 128 m). The results show that our method is capable of transferring the relative vertical accuracy of a fill surface to the void areas in the SRTM model, without introducing uncertainties about the absolute elevation of the fill surface. It is well suited for datasets with varying altitude biases, which is a common problem of older topographic information.

  20. Modeling of surface dust concentrations using neural networks and kriging

    Science.gov (United States)

    Buevich, Alexander G.; Medvedev, Alexander N.; Sergeev, Alexander P.; Tarasov, Dmitry A.; Shichkin, Andrey V.; Sergeeva, Marina V.; Atanasova, T. B.

    2016-12-01

    Creating models which are able to accurately predict the distribution of pollutants based on a limited set of input data is an important task in environmental studies. In the paper two neural approaches: (multilayer perceptron (MLP)) and generalized regression neural network (GRNN)), and two geostatistical approaches: (kriging and cokriging), are using for modeling and forecasting of dust concentrations in snow cover. The area of study is under the influence of dust emissions from a copper quarry and a several industrial companies. The comparison of two mentioned approaches is conducted. Three indices are used as the indicators of the models accuracy: the mean absolute error (MAE), root mean square error (RMSE) and relative root mean square error (RRMSE). Models based on artificial neural networks (ANN) have shown better accuracy. When considering all indices, the most precision model was the GRNN, which uses as input parameters for modeling the coordinates of sampling points and the distance to the probable emissions source. The results of work confirm that trained ANN may be more suitable tool for modeling of dust concentrations in snow cover.

  1. Modelling, simulating and optimizing boiler heating surfaces and evaporator circuits

    DEFF Research Database (Denmark)

    Sørensen, K.; Condra, T.; Houbak, Niels

    2003-01-01

    developed as a Differential-Algebraic-Equation system (DAE) and MATLAB has been applied for the integration of the models. In general MATLAB has proved to be very stable for these DAE systems. Experimental verification has been carried out at a full scale plant equipped with instrumentation to verify heat....... The dynamic model has been developed for the purpose of determining boiler material temperatures and heat transfer from the flue gas side to the water-/steam side in order to simulate the circulation in the evaporator circuit and hereby the water level fluctuations in the drum. The dynamic model has been...

  2. Scattering function for a model of interacting surfaces

    International Nuclear Information System (INIS)

    Colangelo, P.; Gonnella, G.; Maritan, A.

    1993-01-01

    The two-point correlation function of an ensemble of interacting closed self-avoiding surfaces on a cubic lattice is analyzed in the disordered phase, which corresponds to the paramagnetic region in a related spin formulation. Mean-field theory and Monte Carlo simulations predict the existence of a disorder line which corresponds to a transition from an exponential decay to an oscillatory damped behavior of the two-point correlation function. The relevance of the results for the description of amphiphilic systems in a microemulsion phase is discussed. The scattering function is also calculated for a bicontinuous phase coexisting with the paramagnetic phase

  3. A simple model for the surface energy of ionic crystals

    International Nuclear Information System (INIS)

    Roman, E.; Tosi, M.P.

    1982-01-01

    The surface energy of ionic materials is empirically related to bulk properties (elastic constants, electronic dielectric constant and optical band gap) through an analysis of the cleavage force. This is evaluated at small and large separations of the two crystal halves from phonon dispersion curves and from van der Waals interactions, respectively, and these two limiting behaviours are connected by a scaling hypothesis introduced for metals by Kohn and Yaniv. The experimental data that are available for a few ionic crystals seem to satisfy the suggested relation, with an empirical universal parameter which has roughly the same value as determined for metals. (author)

  4. Improving Weather Research and Forecasting Model Initial Conditions via Surface Pressure Analysis

    Science.gov (United States)

    2015-09-01

    boundary layer (ABL). It predicts turbulent kinetic energy (TKE) and is a Mellor-Yamada Level 2.5 turbulence closure model. As in Lee et al. (2012...cumulus parameterization (Kain 2004) is employed. For radiation , the Rapid Radiative Transfer Model (RRTM) (Mlawer et al. 1997) is used for...longwave and the Dudhia scheme (Dudhia 1989) for shortwave . The Noah land surface model (Chen and Dudhia 2001) is used to represent land surface processes

  5. Description of surfaces associated with Grassmannian sigma models on Minkowski space

    International Nuclear Information System (INIS)

    Grundland, A.M.; Snobl, L.

    2005-01-01

    We construct and investigate smooth orientable surfaces in su(N) algebras. The structural equations of surfaces associated with Grassmannian sigma models on Minkowski space are studied using moving frames adapted to the surfaces. The first and second fundamental forms of these surfaces as well as the relations between them as expressed in the Gauss-Weingarten and Gauss-Codazzi-Ricci equations are found. The scalar curvature and the mean curvature vector expressed in terms of a solution of Grassmanian sigma model are obtained

  6. Parameters-related uncertainty in modeling sugar cane yield with an agro-Land Surface Model

    Science.gov (United States)

    Valade, A.; Ciais, P.; Vuichard, N.; Viovy, N.; Ruget, F.; Gabrielle, B.

    2012-12-01

    Agro-Land Surface Models (agro-LSM) have been developed from the coupling of specific crop models and large-scale generic vegetation models. They aim at accounting for the spatial distribution and variability of energy, water and carbon fluxes within soil-vegetation-atmosphere continuum with a particular emphasis on how crop phenology and agricultural management practice influence the turbulent fluxes exchanged with the atmosphere, and the underlying water and carbon pools. A part of the uncertainty in these models is related to the many parameters included in the models' equations. In this study, we quantify the parameter-based uncertainty in the simulation of sugar cane biomass production with the agro-LSM ORCHIDEE-STICS on a multi-regional approach with data from sites in Australia, La Reunion and Brazil. First, the main source of uncertainty for the output variables NPP, GPP, and sensible heat flux (SH) is determined through a screening of the main parameters of the model on a multi-site basis leading to the selection of a subset of most sensitive parameters causing most of the uncertainty. In a second step, a sensitivity analysis is carried out on the parameters selected from the screening analysis at a regional scale. For this, a Monte-Carlo sampling method associated with the calculation of Partial Ranked Correlation Coefficients is used. First, we quantify the sensitivity of the output variables to individual input parameters on a regional scale for two regions of intensive sugar cane cultivation in Australia and Brazil. Then, we quantify the overall uncertainty in the simulation's outputs propagated from the uncertainty in the input parameters. Seven parameters are identified by the screening procedure as driving most of the uncertainty in the agro-LSM ORCHIDEE-STICS model output at all sites. These parameters control photosynthesis (optimal temperature of photosynthesis, optimal carboxylation rate), radiation interception (extinction coefficient), root

  7. Land Surface Modeling and Data Assimilation to Support Physical Precipitation Retrievals for GPM

    Science.gov (United States)

    Peters-Lidard, Christa D.; Tian. Yudong; Kumar, Sujay; Geiger, James; Choudhury, Bhaskar

    2010-01-01

    Objective: The objective of this proposal is to provide a routine land surface modeling and data assimilation capability for GPM in order to provide global land surface states that are necessary to support physical precipitation retrieval algorithms over land. It is well-known that surface emission, particularly over the range of frequencies to be included in GPM, is sensitive to land surface states, including soil properties, vegetation type and greenness, soil moisture, surface temperature, and snow cover, density, and grain size. Therefore, providing a robust capability to routinely provide these critical land states is essential to support GPM-era physical retrieval algorithms over land.

  8. Determination of proteolytic activity using L-[4,5-3H]leucine-labelled globin as a substrate

    International Nuclear Information System (INIS)

    Maliopoulou, T.B.; Dionyssiou-Asteriou, A.; Loucopoulos, D.

    1980-01-01

    A simple and sensitive method for the assay of proteolytic enzyme activity is described. This is based on the digestion of L-[4,5- 3 H]leucine globin by proteolytic enzymes and radioactivity measurement of the trichloroacetic acid soluble cleavage products. (Auth.)

  9. Spatially-varying surface roughness and ground-level air quality in an operational dispersion model

    International Nuclear Information System (INIS)

    Barnes, M.J.; Brade, T.K.; MacKenzie, A.R.; Whyatt, J.D.; Carruthers, D.J.; Stocker, J.; Cai, X.; Hewitt, C.N.

    2014-01-01

    Urban form controls the overall aerodynamic roughness of a city, and hence plays a significant role in how air flow interacts with the urban landscape. This paper reports improved model performance resulting from the introduction of variable surface roughness in the operational air-quality model ADMS-Urban (v3.1). We then assess to what extent pollutant concentrations can be reduced solely through local reductions in roughness. The model results suggest that reducing surface roughness in a city centre can increase ground-level pollutant concentrations, both locally in the area of reduced roughness and downwind of that area. The unexpected simulation of increased ground-level pollutant concentrations implies that this type of modelling should be used with caution for urban planning and design studies looking at ventilation of pollution. We expect the results from this study to be relevant for all atmospheric dispersion models with urban-surface parameterisations based on roughness. -- Highlights: • Spatially variable roughness improved performance of an operational model. • Scenario modelling explored effect of reduced roughness on air pollution. • Reducing surface roughness can increase modelled ground-level pollution. • Damped vertical mixing outweighs increased horizontal advection in model study. • Result should hold for any model with a land-surface coupling based on roughness. -- Spatially varying roughness improves model simulations of urban air pollutant dispersion. Reducing roughness does not always decrease ground-level pollution concentrations

  10. Nicotiana tabacum as model for ozone - plant surface reactions

    Science.gov (United States)

    Jud, Werner; Fischer, Lukas; Wohlfahrt, Georg; Tissier, Alain; Canaval, Eva; Hansel, Armin

    2015-04-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. The ensuing injuries have been related to the uptake of ozone through the stomatal pores and oxidative effects damaging the internal leaf tissue. A striking question of current research is the environment and plant specific partitioning of ozone loss between gas phase, stomatal or plant surface sink terms. Here we show results from ozone fumigation experiments using various Nicotiana Tabacum varieties, whose surfaces are covered with different amounts of unsaturated diterpenoids exuded by their glandular trichomes. Exposure to elevated ozone levels (50 to 150 ppbv) for 5 to 15 hours in an exceptionally clean cuvette system did neither result in a reduction of photosynthesis nor caused any visible leaf damage. Both these ozone induced stress effects have been observed previously in ozone fumigation experiments with the ozone sensitive tobacco line Bel-W3. In our case ozone fumigation was accompanied by a continuous release of oxygenated volatile organic compounds, which could be clearly associated to their condensed phase precursors for the first time. Gas phase reactions of ozone were avoided by choosing a high enough gas exchange rate of the plant cuvette system. In the case of the Ambalema variety, that is known to exude only the diterpenoid cis-abienol, ozone fumigation experiments yield the volatiles formaldehyde and methyl vinyl ketone (MVK). The latter could be unequivocally separated from isomeric methacrolein (MACR) by the aid of a Selective Reagent Ion Time-of-Flight Mass Spectrometer (SRI-ToF-MS), which was switched every six minutes from H3O+ to NO+ primary ion mode and vice versa. Consistent with the picture of an ozone protection mechanism caused by reactive diterpenoids at the leaf surface are the results from dark-light experiments. The ozone loss obtained from the

  11. Simulating Supercapacitors: Can We Model Electrodes As Constant Charge Surfaces?

    Science.gov (United States)

    Merlet, Céline; Péan, Clarisse; Rotenberg, Benjamin; Madden, Paul A; Simon, Patrice; Salanne, Mathieu

    2013-01-17

    Supercapacitors based on an ionic liquid electrolyte and graphite or nanoporous carbon electrodes are simulated using molecular dynamics. We compare a simplified electrode model in which a constant, uniform charge is assigned to each carbon atom with a realistic model in which a constant potential is applied between the electrodes (the carbon charges are allowed to fluctuate). We show that the simulations performed with the simplified model do not provide a correct description of the properties of the system. First, the structure of the adsorbed electrolyte is partly modified. Second, dramatic differences are observed for the dynamics of the system during transient regimes. In particular, upon application of a constant applied potential difference, the increase in the temperature, due to the Joule effect, associated with the creation of an electric current across the cell follows Ohm's law, while unphysically high temperatures are rapidly observed when constant charges are assigned to each carbon atom.

  12. Wetting on micro-structured surfaces: modelling and optimization

    DEFF Research Database (Denmark)

    Cavalli, Andrea

    The present thesis deals with the wetting of micro-structured surfaces by various fluids, and its goal is to elucidate different aspects of this complex interaction. In this work we address some of the most relevant topics in this field such as superhydrophobicity, oleophobicity, unidirectional......-off angles. Such behaviour arises when drops are suspended on a micron or submicron texture, so that their contact with the substrate is minute. This suspended state (known as Cassie-Baxter state) is however prone to failure if the liquid-air interface is perturbed, a common situation in real life...... circumstances. We apply the numerical method of Topology Optimization to this problem, in order to find the optimal texture to support the superhydrophobic configuration. Our optimization provides designs which are consistent with strategies employed by Nature to achieve the same effect. Furthermore, our...

  13. Surface Modeling to Support Small-Body Spacecraft Exploration and Proximity Operations

    Science.gov (United States)

    Riedel, Joseph E.; Mastrodemos, Nickolaos; Gaskell, Robert W.

    2011-01-01

    In order to simulate physically plausible surfaces that represent geologically evolved surfaces, demonstrating demanding surface-relative guidance navigation and control (GN&C) actions, such surfaces must be made to mimic the geological processes themselves. A report describes how, using software and algorithms to model body surfaces as a series of digital terrain maps, a series of processes was put in place that evolve the surface from some assumed nominal starting condition. The physical processes modeled in this algorithmic technique include fractal regolith substrate texturing, fractally textured rocks (of empirically derived size and distribution power laws), cratering, and regolith migration under potential energy gradient. Starting with a global model that may be determined observationally or created ad hoc, the surface evolution is begun. First, material of some assumed strength is layered on the global model in a fractally random pattern. Then, rocks are distributed according to power laws measured on the Moon. Cratering then takes place in a temporal fashion, including modeling of ejecta blankets and taking into account the gravity of the object (which determines how much of the ejecta blanket falls back to the surface), and causing the observed phenomena of older craters being progressively buried by the ejecta of earlier impacts. Finally, regolith migration occurs which stratifies finer materials from coarser, as the fine material progressively migrates to regions of lower potential energy.

  14. Long-term Outcome After Monosegmental L4/5 Stabilization for Degenerative Spondylolisthesis With the Dynesys Device.

    Science.gov (United States)

    Hoppe, Sven; Schwarzenbach, Othmar; Aghayev, Emin; Bonel, Harald; Berlemann, Ulrich

    2016-03-01

    Retrospective analysis of prospectively collected clinical data. To assess the long-term outcome of patients with monosegmental L4/5 degenerative spondylolisthesis treated with the dynamic Dynesys device. The Dynesys system has been used as a semirigid, lumbar dorsal pedicular stabilization device since 1994. Good short-term results have been reported, but little is known about the long-term outcome after treatment for degenerative spondylolisthesis at the L4/5 level. A total of 39 consecutive patients with symptomatic degenerative lumbar spondylolisthesis at the L4/5 level were treated with bilateral decompression and Dynesys instrumentation. At a mean follow-up of 7.2 years (range, 5.0-11.2 y), they underwent clinical and radiographic evaluation and quality of life assessment. At final follow-up, back pain improved in 89% and leg pain improved in 86% of patients compared with preoperative status. Eighty-three percent of patients reported global subjective improvement. Ninety-two percent would undergo the surgery again. Eight patients (21%) required further surgery because of symptomatic adjacent segment disease (6 cases), late-onset infection (1 case), and screw breakage (1 case). In 9 cases, radiologic progression of spondylolisthesis at the operated segment was found. Seventy-four percent of operated segments showed limited flexion-extension range of spondylolisthesis at L4/5 shows good long-term results. The rate of secondary surgeries is comparable to other dorsal instrumentation devices. Residual range of motion in the stabilized segment is reduced, and the rate of radiologic and symptomatic adjacent segment degeneration is low. Patient satisfaction is high. Dynesys stabilization of symptomatic L4/5 degenerative spondylolisthesis is a possible alternative to other stabilization devices.

  15. An Empirical Jet-Surface Interaction Noise Model with Temperature and Nozzle Aspect Ratio Effects

    Science.gov (United States)

    Brown, Cliff

    2015-01-01

    An empirical model for jet-surface interaction (JSI) noise produced by a round jet near a flat plate is described and the resulting model evaluated. The model covers unheated and hot jet conditions (1 less than or equal to jet total temperature ratio less than or equal to 2.7) in the subsonic range (0.5 less than or equal to M(sub a) less than or equal to 0.9), surface lengths 0.6 less than or equal to (axial distance from jet exit to surface trailing edge (inches)/nozzle exit diameter) less than or equal to 10, and surface standoff distances (0 less than or equal to (radial distance from jet lipline to surface (inches)/axial distance from jet exit to surface trailing edge (inches)) less than or equal to 1) using only second-order polynomials to provide predictable behavior. The JSI noise model is combined with an existing jet mixing noise model to produce exhaust noise predictions. Fit quality metrics and comparisons to between the predicted and experimental data indicate that the model is suitable for many system level studies. A first-order correction to the JSI source model that accounts for the effect of nozzle aspect ratio is also explored. This correction is based on changes to the potential core length and frequency scaling associated with rectangular nozzles up to 8:1 aspect ratio. However, more work is needed to refine these findings into a formal model.

  16. The Plumbing of Land Surface Models: Is Poor Performance a Result of Methodology or Data Quality?

    Science.gov (United States)

    Haughton, Ned; Abramowitz, Gab; Pitman, Andy J.; Or, Dani; Best, Martin J.; Johnson, Helen R.; Balsamo, Gianpaolo; Boone, Aaron; Cuntz, Matthais; Decharme, Bertrand; hide

    2016-01-01

    The PALS Land sUrface Model Benchmarking Evaluation pRoject (PLUMBER) illustrated the value of prescribing a priori performance targets in model intercomparisons. It showed that the performance of turbulent energy flux predictions from different land surface models, at a broad range of flux tower sites using common evaluation metrics, was on average worse than relatively simple empirical models. For sensible heat fluxes, all land surface models were outperformed by a linear regression against downward shortwave radiation. For latent heat flux, all land surface models were outperformed by a regression against downward shortwave, surface air temperature and relative humidity. These results are explored here in greater detail and possible causes are investigated. We examine whether particular metrics or sites unduly influence the collated results, whether results change according to time-scale aggregation and whether a lack of energy conservation in fluxtower data gives the empirical models an unfair advantage in the intercomparison. We demonstrate that energy conservation in the observational data is not responsible for these results. We also show that the partitioning between sensible and latent heat fluxes in LSMs, rather than the calculation of available energy, is the cause of the original findings. Finally, we present evidence suggesting that the nature of this partitioning problem is likely shared among all contributing LSMs. While we do not find a single candidate explanation forwhy land surface models perform poorly relative to empirical benchmarks in PLUMBER, we do exclude multiple possible explanations and provide guidance on where future research should focus.

  17. Elastic scattering of surface plasmon polaritons: Modeling and experiment

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Coello, V.

    1998-01-01

    excitation wavelengths (594 and 633 nm) and different metal (silver and gold) films. The near-field optical images obtained are related to the calculated SPP intensity distributions demonstrating that the model developed can be successfully used in studies of SPP elastic scattering, e.g., to design...

  18. Integrated Computational Modelling of Thermochemical Surface Engineering of Stainless Steel

    DEFF Research Database (Denmark)

    Kücükyildiz, Ömer Can; Sonne, Mads Rostgaard; Thorborg, Jesper

    2017-01-01

    An implicit finite difference method (FDM) based numerical model for the prediction of composition- and stress-depth profiles developing during low temperature gas nitriding (LTGN) of 316 stainless steel is presented. The essential effects governing the kinetics of composition and coupled stress ...

  19. A Comparison and Validation of Two Surface Ship Readiness Models

    Science.gov (United States)

    1994-09-01

    they cannot be considered validated. Any application of these programs without additional verification is at the risk of the user. vii Vifi TABLE OF...contains the S’AS code that was used to perform the full model run for the SIM. // SIMIC JOB USER=S6402,CLASS--C 1/ EXEC SAS //WORK DD UNIT=SYSDASPACE

  20. A TESSELLATION MODEL FOR CRACK PATTERNS ON SURFACES

    Directory of Open Access Journals (Sweden)

    Werner Nagel

    2011-05-01

    Full Text Available This paper presents a model of random tessellations that reflect several features of crack pattern. There are already several theoretical results derivedwhich indicate that thismodel can be an appropriate referencemodel. Some potential applications are presented in a tentative statistical study.

  1. Modelling of Surface Ships using Artificial Neural Networks

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Jensen, F. M.; Thoft-Christensen, Palle

    For various design and planning purposes there is at present an increasing interest and a need for numerical modelling of the process of navigating a vessel (or a floating body in general). The reasons for this is that experiments in "full mission" simulators with human navigators at the handles ...

  2. Hydrological model for the transport of radioisotope in surface water

    International Nuclear Information System (INIS)

    Adoboah, E.K.

    2011-01-01

    The use of radioisotopes has gained grounds in Ghana as a result of the numerous benefits that could be derived from it. In Ghana, radioisotope materials are used for various purposes in a number of institutions. However, improper disposal of the waste poses threat to the environment. To evaluate the environmental impact of radioisotope pollution, mathematical models play a major role in predicting the pollution level in any medium. This study is concerned with the hydrological model for the transport of radioactive material in the river. The model was composed by employing partial differential equations, describing relevant physical processes evolution (water level, velocities and dissolved substances concentrations) that occurs in water bodies. The mass conservation and momentum laws, state equation and state transport equations are equation system basis. The explicit central difference scheme in space and a forward difference method in time were used for the evaluation of the generalized transport equation, the Advection-Dispersion Equation. A Matlab code was developed to predict the concentration of the radioactive contaminant at any particular time along the river and in a reservoir. The model was able to simulate accurately the various levels of radionuclide concentration changes in the flowing rivers as the flows are augmented by tributary inflows. (au)

  3. Verification and transfer of thermal pollution model. Volume 2: User's manual for 3-dimensional free-surface model

    Science.gov (United States)

    Lee, S. S.; Sengupta, S.; Tuann, S. Y.; Lee, C. R.

    1982-01-01

    The six-volume report: describes the theory of a three-dimensional (3-D) mathematical thermal discharge model and a related one-dimensional (1-D) model, includes model verification at two sites, and provides a separate user's manual for each model. The 3-D model has two forms: free surface and rigid lid. The former, verified at Anclote Anchorage (FL), allows a free air/water interface and is suited for significant surface wave heights compared to mean water depth; e.g., estuaries and coastal regions. The latter, verified at Lake Keowee (SC), is suited for small surface wave heights compared to depth. These models allow computation of time-dependent velocity and temperature fields for given initial conditions and time-varying boundary conditions.

  4. An empirical model for the statistics of sea surface diurnal warming

    Directory of Open Access Journals (Sweden)

    M. J. Filipiak

    2012-03-01

    Full Text Available A statistical model is derived relating the diurnal variation of sea surface temperature (SST to the net surface heat flux and surface wind speed from a numerical weather prediction (NWP model. The model is derived using fluxes and winds from the European Centre for Medium-Range Weather Forecasting (ECMWF NWP model and SSTs from the Spinning Enhanced Visible and Infrared Imager (SEVIRI. In the model, diurnal warming has a linear dependence on the net surface heat flux integrated since (approximately dawn and an inverse quadratic dependence on the maximum of the surface wind speed in the same period. The model coefficients are found by matching, for a given integrated heat flux, the frequency distributions of the maximum wind speed and the observed warming. Diurnal cooling, where it occurs, is modelled as proportional to the integrated heat flux divided by the heat capacity of the seasonal mixed layer. The model reproduces the statistics (mean, standard deviation, and 95-percentile of the diurnal variation of SST seen by SEVIRI and reproduces the geographical pattern of mean warming seen by the Advanced Microwave Scanning Radiometer (AMSR-E. We use the functional dependencies in the statistical model to test the behaviour of two physical model of diurnal warming that display contrasting systematic errors.

  5. Modeling of type-2 fuzzy cubic B-spline surface for flood data problem in Malaysia

    Science.gov (United States)

    Bidin, Mohd Syafiq; Wahab, Abd. Fatah

    2017-08-01

    Malaysia possesses a low and sloping land areas which may cause flood. The flood phenomenon can be analyzed if the surface data of the study area can be modeled by geometric modeling. Type-2 fuzzy data for the flood data is defined using type-2 fuzzy set theory in order to solve the uncertainty of complex data. Then, cubic B-spline surface function is used to produce a smooth surface. Three main processes are carried out to find a solution to crisp type-2 fuzzy data which is fuzzification (α-cut operation), type-reduction and defuzzification. Upon conducting these processes, Type-2 Fuzzy Cubic B-Spline Surface Model is applied to visualize the surface data of the flood areas that are complex uncertainty.

  6. A theoretical model for the scattering of I2 molecule from a perfluoropolyeter liquid surface

    Directory of Open Access Journals (Sweden)

    Leal Alexandre S.

    1999-01-01

    Full Text Available In order to simulate experimental results of scattering of an I2 beam from liquid perfluorpolyeter ( PFPE surface we developed a model potential for the gas-polymer interaction at the liquid surface and solved the dynamics of the collision process by the classical trajectory method. The energy transferred in the process to the vibrational mode of the I2 molecule and to the liquid surface was investigated as a function of potential parameters.

  7. Modeling dose-rate on/over the surface of cylindrical radio-models using Monte Carlo methods

    International Nuclear Information System (INIS)

    Xiao Xuefu; Ma Guoxue; Wen Fuping; Wang Zhongqi; Wang Chaohui; Zhang Jiyun; Huang Qingbo; Zhang Jiaqiu; Wang Xinxing; Wang Jun

    2004-01-01

    Objective: To determine the dose-rates on/over the surface of 10 cylindrical radio-models, which belong to the Metrology Station of Radio-Geological Survey of CNNC. Methods: The dose-rates on/over the surface of 10 cylindrical radio-models were modeled using the famous Monte Carlo code-MCNP. The dose-rates on/over the surface of 10 cylindrical radio-models were measured by a high gas pressurized ionization chamber dose-rate meter, respectively. The values of dose-rate modeled using MCNP code were compared with those obtained by authors in the present experimental measurement, and with those obtained by other workers previously. Some factors causing the discrepancy between the data obtained by authors using MCNP code and the data obtained using other methods are discussed in this paper. Results: The data of dose-rates on/over the surface of 10 cylindrical radio-models, obtained using MCNP code, were in good agreement with those obtained by other workers using the theoretical method. They were within the discrepancy of ±5% in general, and the maximum discrepancy was less than 10%. Conclusions: As if each factor needed for the Monte Carlo code is correct, the dose-rates on/over the surface of cylindrical radio-models modeled using the Monte Carlo code are correct with an uncertainty of 3%

  8. Modeling Manganese Sorption and Surface Oxidation During Filtration

    OpenAIRE

    Bierlein, Kevin Andrew

    2012-01-01

    Soluble manganese (Mn) is a common contaminant in drinking water sources. High levels of Mn can lead to aesthetic water quality problems, necessitating removal of Mn during treatment to minimize consumer complaints. Mn may be removed during granular media filtration by the â natural greensand effect,â in which soluble Mn adsorbs to manganese oxide-coated (MnOx(s)) media and is then oxidized by chlorine, forming more manganese oxide. This research builds on a previous model developed by Mer...

  9. Development of a dynamic model for cleaning ultra filtration membranes fouled by surface water

    NARCIS (Netherlands)

    Zondervan, E.; Betlem, Bernardus H.L.; Roffel, B.

    2007-01-01

    In this paper, a dynamic model for cleaning ultra filtration membranes fouled by surface water is proposed. A model that captures the dynamics well is valuable for the optimization of the cleaning process. The proposed model is based on component balances and contains three parameters that can be

  10. A model for diffuse and global irradiation on horizontal surface

    International Nuclear Information System (INIS)

    Jain, P.C.

    1984-01-01

    The intensity of the direct radiation and the diffuse radiation at any time on a horizontal surface are each expressed as fractions of the intensity of the extraterrestrial radiation. Using these and assuming a random distribution of the bright sunshine hours and not too wide variations in the values of the transmission coefficients, a number of relations for estimating the global and the diffuse irradiation are derived. Two of the relations derived are already known empirically. The formulation lends more confidence in the use of the already empirically known relations providing them a theoretical basis, and affords more flexibility to the estimation techniques by supplying new equations. The study identifies three independent basic parameters and the constants appearing in the various equations as simple functions of these three basic parameters. Experimental data for the diffuse irradiation, the global irradiation and the bright sunshine duration for Macerata (Italy), Salisbury and Bulawayo (Zimbabwe) is found to show good correlation for the linear equations, and the nature and the interrelationships of the constants are found to be as predicted by the theory

  11. A Coupled Groundwater-Surface Water Modeling Framework for Simulating Transition Zone Processes.

    Science.gov (United States)

    Mugunthan, Pradeep; Russell, Kevin T; Gong, Binglei; Riley, Michael J; Chin, Arthur; McDonald, Blair G; Eastcott, Linda J

    2017-05-01

    There is an identified need for fully representing groundwater-surface water transition zone (i.e., the sediment zone that connects groundwater and surface water) processes in modeling fate and transport of contaminants to assist with management of contaminated sediments. Most existing groundwater and surface water fate and transport models are not dynamically linked and do not consider transition zone processes such as bioturbation and deposition and erosion of sediments. An interface module is developed herein to holistically simulate the fate and transport by coupling two commonly used models, Environmental Fluid Dynamics Code (EFDC) and SEAWAT, to simulate surface water and groundwater hydrodynamics, while providing an enhanced representation of the processes in the transition zone. Transition zone and surface water contaminant processes were represented through an enhanced version of the EFDC model, AQFATE. AQFATE also includes SEDZLJ, a state-of-the-science surface water sediment transport model. The modeling framework was tested on a published test problem and applied to evaluate field-scale two- and three-dimensional contaminant transport. The model accurately simulated concentrations of salinity from a published test case. For the field-scale applications, the model showed excellent mass balance closure for the transition zone and provided accurate simulations of all transition zone processes represented in the modeling framework. The model predictions for the two-dimensional field case were consistent with site-specific observations of contaminant migration. This modeling framework represents advancement in the simulation of transition zone processes and can help inform risk assessment at sites where contaminant sources from upland areas have the potential to impact sediments and surface water. © 2016, National Ground Water Association.

  12. Navier-Stokes Computations With One-Equation Turbulence Model for Flows Along Concave Wall Surfaces

    Science.gov (United States)

    Wang, Chi R.

    2005-01-01

    This report presents the use of a time-marching three-dimensional compressible Navier-Stokes equation numerical solver with a one-equation turbulence model to simulate the flow fields developed along concave wall surfaces without and with a downstream extension flat wall surface. The 3-D Navier- Stokes numerical solver came from the NASA Glenn-HT code. The one-equation turbulence model was derived from the Spalart and Allmaras model. The computational approach was first calibrated with the computations of the velocity and Reynolds shear stress profiles of a steady flat plate boundary layer flow. The computational approach was then used to simulate developing boundary layer flows along concave wall surfaces without and with a downstream extension wall. The author investigated the computational results of surface friction factors, near surface velocity components, near wall temperatures, and a turbulent shear stress component in terms of turbulence modeling, computational mesh configurations, inlet turbulence level, and time iteration step. The computational results were compared with existing measurements of skin friction factors, velocity components, and shear stresses of the developing boundary layer flows. With a fine computational mesh and a one-equation model, the computational approach could predict accurately the skin friction factors, near surface velocity and temperature, and shear stress within the flows. The computed velocity components and shear stresses also showed the vortices effect on the velocity variations over a concave wall. The computed eddy viscosities at the near wall locations were also compared with the results from a two equation turbulence modeling technique. The inlet turbulence length scale was found to have little effect on the eddy viscosities at locations near the concave wall surface. The eddy viscosities, from the one-equation and two-equation modeling, were comparable at most stream-wise stations. The present one

  13. Surface roughness prediction model in end milling of Al/SiC p MMC ...

    African Journals Online (AJOL)

    This research focuses on study and analyses of surface quality improvement in end milling operation of Al/SiCp metal matrix composite. These materials are selected as they are most widely used in automobile and aerospace industry. This research paper develops an improved mathematical model for surface roughness ...

  14. MODELING OF QUALITY FORMATION OF PIG IRON BILLET SURFACE AT WIRE BRUSH MILLING

    Directory of Open Access Journals (Sweden)

    I. L. Barshaj

    2009-01-01

    Full Text Available Formation of topography, geometrical structure and micro-hardness of pig iron billet surface is considered in the paper. Mathematical models pertaining to formation of the above-mentioned characteristics of surface quality according to parameters of machining regime have been developed on the basis of the executed investigations.

  15. Modelling evapotranspiration using the surface energy balance systems (sebs) and landsat tm data (rabat region, morocco)

    NARCIS (Netherlands)

    Kwast, J. van der; Jong, S.M. de

    2004-01-01

    Modelling and understanding the surface energy balance is important for assessing the re-distribution of moisture and heat in soil and atmosphere. The Surface Energy Balance System (SEBS) estimates turbulent heat fluxes using satellite earth observation data in the visible, near infrared, and

  16. Evaluation of alternative surface runoff accounting procedures using the SWAT model

    Science.gov (United States)

    For surface runoff estimation in the Soil and Water Assessment Tool (SWAT) model, the curve number (CN) procedure is commonly adopted to calculate surface runoff by utilizing antecedent soil moisture condition (SCSI) in field. In the recent version of SWAT (SWAT2005), an alternative approach is ava...

  17. a model study of surface state on optical bandgap of silicon nanowires

    African Journals Online (AJOL)

    Dr A.B.Ahmed

    to quantum confinement and surface passivation. But the energy recombination of electron and holes in the quantum confined nanostructures is responsible for the visible PL. In this work, models from quantum bandgap and photoluminescence intensity are adopted to explain the size dependent surface luminescence.

  18. Evaluating the JULES Land Surface Model Energy Fluxes Using FLUXNET Data

    NARCIS (Netherlands)

    Blyth, E.; Gash, J.H.C.; Lloyd, A.J.; Pryor, M.; Weedon, G.P.; Shuttleworth, J.

    2010-01-01

    Surface energy flux measurements from a sample of 10 flux network (FLUXNET) sites selected to represent a range of climate conditions and biome types were used to assess the performance of the Hadley Centre land surface model (Joint U. K. Land Environment Simulator; JULES). Because FLUXNET data are

  19. Extracting surface diffusion coefficients from batch adsorption measurement data: application of the classic Langmuir kinetics model.

    Science.gov (United States)

    Chu, Khim Hoong

    2017-11-09

    Surface diffusion coefficients may be estimated by fitting solutions of a diffusion model to batch kinetic data. For non-linear systems, a numerical solution of the diffusion model's governing equations is generally required. We report here the application of the classic Langmuir kinetics model to extract surface diffusion coefficients from batch kinetic data. The use of the Langmuir kinetics model in lieu of the conventional surface diffusion model allows derivation of an analytical expression. The parameter estimation procedure requires determining the Langmuir rate coefficient from which the pertinent surface diffusion coefficient is calculated. Surface diffusion coefficients within the 10 -9 to 10 -6  cm 2 /s range obtained by fitting the Langmuir kinetics model to experimental kinetic data taken from the literature are found to be consistent with the corresponding values obtained from the traditional surface diffusion model. The virtue of this simplified parameter estimation method is that it reduces the computational complexity as the analytical expression involves only an algebraic equation in closed form which is easily evaluated by spreadsheet computation.

  20. The ground surface energy balance in modelling horizontal ground heat exchangers

    Science.gov (United States)

    Bortoloni, M.; Bottarelli, M.; Su, Y.

    2017-01-01

    The performance of horizontal ground heat exchangers (HGHEs) is strongly dependent on climatic conditions, due to the low installation depth. In numerical modelling of HGHEs, the estimation of shallow soil temperature distribution is a key issue, therefore the boundary condition (BC) at the ground surface should be assigned carefully. With this in mind, a model of the energy balance at the ground surface (GSEB), based on weather variables, was developed. The model was tested as the 3rd kind BC at ground surface in modelling HGHEs by means of the FEM code Comsol Multiphysics, solving the unsteady heat transfer problem in a 2D domain. The GSEB model was calibrated and validated with the observed soil temperature at different depths. In addition, the effect on numerical solutions of different BCs, when assigned at the ground surface, was analysed. Three different simulations were carried out applying the GSEB model, the equivalent surface heat flux and temperature as boundary conditions of the 1st, 2nd and 3rd kind, respectively. The results of this study indicate that the use of the GSEB model is a preferable approach to the problem and that the use of the equivalent surface temperature can be considered as a reasonable simplification.