Calibration of a 1D/1D urban flood model using 1D/2D model results in the absence of field data.
Leandro, J; Djordjević, S; Chen, A S; Savić, D A; Stanić, M
2011-01-01
Recently increased flood events have been prompting researchers to improve existing coupled flood-models such as one-dimensional (1D)/1D and 1D/two-dimensional (2D) models. While 1D/1D models simulate sewer and surface networks using a one-dimensional approach, 1D/2D models represent the surface network by a two-dimensional surface grid. However their application raises two issues to urban flood modellers: (1) stormwater systems planning/emergency or risk analysis demands for fast models, and the 1D/2D computational time is prohibitive, (2) and the recognized lack of field data (e.g. Hunter et al. (2008)) causes difficulties for the calibration/validation of 1D/1D models. In this paper we propose to overcome these issues by calibrating a 1D/1D model with the results of a 1D/2D model. The flood-inundation results show that: (1) 1D/2D results can be used to calibrate faster 1D/1D models, (2) the 1D/1D model is able to map the 1D/2D flood maximum extent well, and the flooding limits satisfactorily in each time-step, (3) the 1D/1D model major differences are the instantaneous flow propagation and overestimation of the flood-depths within surface-ponds, (4) the agreement in the volume surcharged by both models is a necessary condition for the 1D surface-network validation and (5) the agreement of the manholes discharge shapes measures the fitness of the calibrated 1D surface-network.
Brady 1D seismic velocity model ambient noise prelim
Mellors, Robert J.
2013-10-25
Preliminary 1D seismic velocity model derived from ambient noise correlation. 28 Green's functions filtered between 4-10 Hz for Vp, Vs, and Qs were calculated. 1D model estimated for each path. The final model is a median of the individual models. Resolution is best for the top 1 km. Poorly constrained with increasing depth.
Modeling an electric motor in 1-D
NASA Technical Reports Server (NTRS)
Butler, Thomas G.
1991-01-01
Quite often the dynamicist will be faced with having an electric drive motor as a link in the elastic path of a structure such that the motor's characteristics must be taken into account to properly represent the dynamics of the primary structure. He does not want to model it so accurately that he could get detailed stress and displacements in the motor proper, but just sufficiently to represent its inertia loading and elastic behavior from its mounting bolts to its drive coupling. Described here is how the rotor and stator of such a motor can be adequately modeled as a colinear pair of beams.
GIS-BASED 1-D DIFFUSIVE WAVE OVERLAND FLOW MODEL
KALYANAPU, ALFRED; MCPHERSON, TIMOTHY N.; BURIAN, STEVEN J.
2007-01-17
This paper presents a GIS-based 1-d distributed overland flow model and summarizes an application to simulate a flood event. The model estimates infiltration using the Green-Ampt approach and routes excess rainfall using the 1-d diffusive wave approximation. The model was designed to use readily available topographic, soils, and land use/land cover data and rainfall predictions from a meteorological model. An assessment of model performance was performed for a small catchment and a large watershed, both in urban environments. Simulated runoff hydrographs were compared to observations for a selected set of validation events. Results confirmed the model provides reasonable predictions in a short period of time.
Lee, S.
2011-05-17
The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four dual-nozzle slurry pumps located within the tank liquid. For the work, a Tank 48 simulation model with a maximum of four slurry pumps in operation has been developed to estimate flow patterns for efficient solid mixing. The modeling calculations were performed by using two modeling approaches. One approach is a single-phase Computational Fluid Dynamics (CFD) model to evaluate the flow patterns and qualitative mixing behaviors for a range of different modeling conditions since the model was previously benchmarked against the test results. The other is a two-phase CFD model to estimate solid concentrations in a quantitative way by solving the Eulerian governing equations for the continuous fluid and discrete solid phases over the entire fluid domain of Tank 48. The two-phase results should be considered as the preliminary scoping calculations since the model was not validated against the test results yet. A series of sensitivity calculations for different numbers of pumps and operating conditions has been performed to provide operational guidance for solids suspension and mixing in the tank. In the analysis, the pump was assumed to be stationary. Major solid obstructions including the pump housing, the pump columns, and the 82 inch central support column were included. The steady state and three-dimensional analyses with a two-equation turbulence model were performed with FLUENT{trademark} for the single-phase approach and CFX for the two-phase approach. Recommended operational guidance was developed assuming that local fluid velocity can be used as a measure of sludge suspension and spatial mixing under single-phase tank model. For quantitative analysis, a two-phase fluid-solid model was developed for the same modeling conditions as the single
SINDA/FLUINT Stratified Tank Modeling for Cryrogenic Propellant Tanks
NASA Technical Reports Server (NTRS)
Sakowski, Barbara
2014-01-01
A general purpose SINDA/FLUINT (S/F) stratified tank model was created to simulate self-pressurization and axial jet TVS; Stratified layers in the vapor and liquid are modeled using S/F lumps.; The stratified tank model was constructed to permit incorporating the following additional features:, Multiple or singular lumps in the liquid and vapor regions of the tank, Real gases (also mixtures) and compressible liquids, Venting, pressurizing, and draining, Condensation and evaporation/boiling, Wall heat transfer, Elliptical, cylindrical, and spherical tank geometries; Extensive user logic is used to allow detailed tailoring - Don't have to rebuilt everything from scratch!!; Most code input for a specific case is done through the Registers Data Block:, Lump volumes are determined through user input:; Geometric tank dimensions (height, width, etc); Liquid level could be input as either a volume percentage of fill level or actual liquid level height
JULYK, L.J.; MACKEY, T.C.
2003-06-19
Summary report of ANSYS finite element models developed for dome load analysis of Hanford 100-series single-shell tanks and double-shell tanks. Document provides user interface for selecting proper tank model and changing of analysis parameters for tank specific analysis. Current dome load restrictions for the Hanford Site underground waste storage tanks are based on existing analyses of record (AOR) that evaluated the tanks for a specific set of design load conditions. However, greater flexibility is required in controlling dome loadings applied to the tanks due to day-to-day operations and waste retrieval activities. This requires the development of an analytical model with sufficient detail to evaluate various dome loading conditions not specifically addressed in the AOR.
Non-cooperative Brownian donkeys: A solvable 1D model
NASA Astrophysics Data System (ADS)
Jiménez de Cisneros, B.; Reimann, P.; Parrondo, J. M. R.
2003-12-01
A paradigmatic 1D model for Brownian motion in a spatially symmetric, periodic system is tackled analytically. Upon application of an external static force F the system's response is an average current which is positive for F < 0 and negative for F > 0 (absolute negative mobility). Under suitable conditions, the system approaches 100% efficiency when working against the external force F.
Nonlocal order parameters for the 1D Hubbard model.
Montorsi, Arianna; Roncaglia, Marco
2012-12-07
We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point U(c)=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at U(c). The behavior of the parity correlators is captured by an effective free spinless fermion model.
Nonlocal Order Parameters for the 1D Hubbard Model
NASA Astrophysics Data System (ADS)
Montorsi, Arianna; Roncaglia, Marco
2012-12-01
We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point Uc=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at Uc. The behavior of the parity correlators is captured by an effective free spinless fermion model.
Evaluating 1d Seismic Models of the Lunar Interior
NASA Astrophysics Data System (ADS)
Yao, Y.; Thorne, M. S.; Weber, R. C.; Schmerr, N. C.
2012-12-01
A four station seismic network was established on the Moon from 1969 to 1977 as part of the Apollo Lunar Surface Experiment Package (ALSEP). A total of nine 1D seismic velocity models were generated using a variety of different techniques. In spite of the fact that these models were generated from the same data set, significant differences exist between them. We evaluate these models by comparing predicted travel-times to published catalogs of lunar events. We generate synthetic waveform predictions for 1D lunar models using a modified version of the Green's Function of the Earth by Minor Integration (GEMINI) technique. Our results demonstrate that the mean square errors between predicted and measured P-wave travel times are smaller than those for S-wave travel times in all cases. Moreover, models fit travel times for artificial and meteoroid impacts better than for shallow and deep moonquakes. Overall, models presented by Nakamura [Nakamura, 1983] and Garcia et al. [Garcia et al., 2011] predicted the observed travel times better than all other models and were comparable in their explanation of travel-times. Nevertheless, significant waveform differences exist between these models. In particular, the seismic velocity structure of the lunar crust and regolith strongly affect the waveform characteristics predicted by these models. Further complexity is added by possible mantle discontinuity structure that exists in a subset of these models. We show synthetic waveform predictions for these models demonstrating the role that crustal structure has in generating long duration seismic coda inherent in the lunar waveforms.
1-D blood flow modelling in a running human body.
Szabó, Viktor; Halász, Gábor
2017-04-10
In this paper an attempt was made to simulate blood flow in a mobile human arterial network, specifically, in a running human subject. In order to simulate the effect of motion, a previously published immobile 1-D model was modified by including an inertial force term into the momentum equation. To calculate inertial force, gait analysis was performed at different levels of speed. Our results show that motion has a significant effect on the amplitudes of the blood pressure and flow rate but the average values are not effected significantly.
Constitutive modeling and control of 1D smart composite structures
NASA Astrophysics Data System (ADS)
Briggs, Jonathan P.; Ostrowski, James P.; Ponte-Castaneda, Pedro
1998-07-01
Homogenization techniques for determining effective properties of composite materials may provide advantages for control of stiffness and strain in systems using hysteretic smart actuators embedded in a soft matrix. In this paper, a homogenized model of a 1D composite structure comprised of shape memory alloys and a rubber-like matrix is presented. With proportional and proportional/integral feedback, using current as the input state and global strain as an error state, implementation scenarios include the use of tractions on the boundaries and a nonlinear constitutive law for the matrix. The result is a simple model which captures the nonlinear behavior of the smart composite material system and is amenable to experiments with various control paradigms. The success of this approach in the context of the 1D model suggests that the homogenization method may prove useful in investigating control of more general smart structures. Applications of such materials could include active rehabilitation aids, e.g. wrist braces, as well as swimming/undulating robots, or adaptive molds for manufacturing processes.
Enhanced Waste Tank Level Model
Duignan, M.R.
1999-06-24
'With the increased sensitivity of waste-level measurements in the H-Area Tanks and with periods of isolation, when no mass transfer occurred for certain tanks, waste-level changes have been recorded with are unexplained.'
Combinatorial approach to exactly solve the 1D Ising model
NASA Astrophysics Data System (ADS)
Seth, Swarnadeep
2017-01-01
The Ising model is a well known statistical model which can be solved exactly by various methods. The most familiar one is the transfer matrix method. Sometimes it can be difficult to approach the open boundary case rather than periodic boundary ones in higher dimensions. But physically it is more intuitive to study the open boundary case, as it gives a closer view of the real system. We have introduced a new method called the pairing method to determine the exact partition function for the simplest case, a 1D Ising lattice. This method simplifies the problem's complexities and reduces it to a pure combinatorial problem. The study also reveals that it is possible to apply this pairing method in the case of a 2D square lattice. The obtained results agree perfectly with the values in the literature and this new approach provides an algorithmic insight to deal with such problems.
Examination of 1D Solar Cell Model Limitations Using 3D SPICE Modeling: Preprint
McMahon, W. E.; Olson, J. M.; Geisz, J. F.; Friedman, D. J.
2012-06-01
To examine the limitations of one-dimensional (1D) solar cell modeling, 3D SPICE-based modeling is used to examine in detail the validity of the 1D assumptions as a function of sheet resistance for a model cell. The internal voltages and current densities produced by this modeling give additional insight into the differences between the 1D and 3D models.
Lanczos diagonalizations of the 1-D Peierls-Hubbard model
Loh, E.Y.; Campbell, D.K.; Gammel, J.T.
1989-01-01
In studies of interacting electrons in reduced dimensions'' one is trapped between the Scylla of exponential growth of the number of states in any exact many-body basis and the Charybdis of the failure of mean-field theories to capture adequately the effects of interactions. In the present article we focus on one technique -- the Lanczos method -- which, at least in the case of the 1-D Peierls-Hubbard model, appears to allow us to sail the narrow channel between these two hazards. In contrast to Quantum Monte Carlo methods, which circumvent the exponential growth of states by statistical techniques and importance sampling, the Lanczos approach attacks this problem head-on by diagonalizing the full Hamiltonian. Given the restrictions of present computers, this approach is thus limited to studying finite clusters of roughly 12--14 sites. Fortunately, in one dimension, such clusters are usually sufficient for extracting many of the properties of the infinite system provided that one makes full use of the ability to vary the boundary conditions. In this article we shall apply the Lanczos methodology and novel phase randomization'' techniques to study the 1-D Peierls-Hubbard model, with particular emphasis on the optical absorption properties, including the spectrum of absorptions as a function of photon energy. Despite the discreteness of the eigenstates in our finite clusters, we are able to obtain optical spectra that, in cases where independent tests can be made, agree well with the known exact results for the infinite system. Thus we feel that this combination of techniques represents an important and viable means of studying many interesting novel materials involving strongly correlated electrons. 26 refs., 6 figs.
Cavitation Influence in 1D Part-load Vortex Models
NASA Astrophysics Data System (ADS)
Dörfler, P. K.
2016-11-01
Residual swirl in the draft tube of Francis turbines may cause annoying low- frequency pulsation of pressure and power output, in particular during part-load operation. A 1D analytical model for these dynamic phenomena would enable simulation by some conventional method for computing hydraulic transients. The proper structure of such a model has implications for the prediction of prototype behaviour based on laboratory tests. The source of excitation as well as the dynamic transmission behaviour of the draft tube flow may both be described either by lumped or distributed parameters. The distributed version contains more information and, due to limited possibilities of identification, some data must be estimated. The distributed cavitation compliance is an example for this dilemma. In recent publications, the customary assumption of a constant wave speed has produced dubious results. The paper presents a more realistic model for distributed compressibility. The measured influence of the Thoma number is applied with the local cavitation factor. This concept is less sensitive to modelling errors and explains both the Thoma and Froude number influence. The possible effect of the normally unknown non-condensable gas content in the vortex cavity is shortly commented. Its measurement in future tests is recommended. It is also recommended to check the available analytical vortex models for possible dispersion effects.
1-D Modeling of Massive Particle Injection (MPI) in Tokamaks
NASA Astrophysics Data System (ADS)
Wu, W.; Parks, P. B.; Izzo, V. A.
2008-11-01
A 1-D Fast Current Quench (FCQ) model is developed to study current evolution and runaway electron suppression under massive density increase. The model consists of coupled toroidal electric field and energy equations, and it is solved numerically for DIII-D and ITER operating conditions. Simulation results suggest that fast shutdown by D2 liquid jet/pellet injection is in principle achievable for the desired plasma cooling time (˜15 ms for DIII-D and ˜50 ms for ITER) under ˜150x or higher densification. The current density and pressure profile are practically unaltered during the initial phase of jet propagation when dilution cooling dominates. With subsequent radiation cooling, the densified discharge enters the strongly collisional regime where Pfirsch-Schluter thermal diffusion can inhibit current contraction on the magnetic axis. Often the 1/1 kink instability, addressed by Kadomtsev's magnetic reconnection model, can be prevented. Our results are compared with NIMROD simulations in which the plasma is suddenly densified by ˜100x and experiences instantaneous dilution cooling, allowing for use of actual (lower) Lundquist numbers.
An improved approach for tank purge modeling
NASA Astrophysics Data System (ADS)
Roth, Jacob R.; Chintalapati, Sunil; Gutierrez, Hector M.; Kirk, Daniel R.
2013-05-01
Many launch support processes use helium gas to purge rocket propellant tanks and fill lines to rid them of hazardous contaminants. As an example, the purge of the Space Shuttle's External Tank used approximately 1,100 kg of helium. With the rising cost of helium, initiatives are underway to examine methods to reduce helium consumption. Current helium purge processes have not been optimized using physics-based models, but rather use historical 'rules of thumb'. To develop a more accurate and useful model of the tank purge process, computational fluid dynamics simulations of several tank configurations were completed and used as the basis for the development of an algebraic model of the purge process. The computationally efficient algebraic model of the purge process compares well with a detailed transient, three-dimensional computational fluid dynamics (CFD) simulation as well as with experimental data from two external tank purges.
Sinda/Fluint Stratfied Tank Modeling
NASA Technical Reports Server (NTRS)
Sakowski, Barbara A.
2014-01-01
A general purpose SINDA/FLUINT (S/F) stratified tank model was created and used to simulate the Ksite1 LH2 liquid self-pressurization tests as well as axial jet mixing within the liquid region of the tank. The S/F model employed the use of stratified layers, i.e. S/F lumps, in the vapor ullage as well as in the liquid region. The model was constructed to analyze a general purpose stratified tank that could incorporate the following features: Multiple or singular lumps in the liquid and vapor regions of the tank, Real gases (also mixtures) and compressible liquids, Venting, pressurizing, and draining, Condensation and evaporation/boiling, Wall heat transfer, Elliptical, cylindrical, and spherical tank geometries. Extensive user logic was used to allow for tailoring of the above features to specific cases. Most of the code input for a specific case could be done through the Registers Data Block.
Modeling shear band interaction in 1D torsion
NASA Astrophysics Data System (ADS)
Partom, Yehuda; Hanina, Erez
2017-01-01
When two shear bands are being formed at close distance from each other they interact, and further development of one of them may be quenched down. As a result there should be a minimum distance between shear bands. In the literature there are at least three analytical models for this minimum distance. Predictions of these models do not generally agree with each other and with test results. Recently we developed a 1D numerical scheme to predict the formation of shear bands in a torsion test of a thin walled pipe. We validated our code by reproducing results of the pioneering experiments of Marchand and Duffy, and then used it to investigate the mechanics of shear localization and shear band formation. We describe our shear band code in a separate publication, and here we use it only as a tool to investigate the interaction between two neighboring shear bands during the process of their formation. We trigger the formation of shear bands by specifying two perturbations of the initial strength. We vary the perturbations in terms of their amplitude and/or their width. Usually, the stronger perturbation triggers a faster developing shear band, which then prevails and quenches the development of the other shear band. We change the distance between the two shear bands and find, that up to a certain distance one of the shear bands becomes fully developed, and the other stays only partially developed. Beyond this distance the two shear bands are both fully developed. Finally, we check the influence of certain material and loading parameters on the interaction between the two shear bands, and compare the results to predictions of the analytical models from the literature.
Torfs, Elena; Balemans, Sophie; Locatelli, Florent; Diehl, Stefan; Bürger, Raimund; Laurent, Julien; François, Pierre; Nopens, Ingmar
2017-03-01
Advanced 1-D models for Secondary Settling Tanks (SSTs) explicitly account for several phenomena that influence the settling process (such as hindered settling and compression settling). For each of these phenomena a valid mathematical expression needs to be selected and its parameters calibrated to obtain a model that can be used for operation and control. This is, however, a challenging task as these phenomena may occur simultaneously. Therefore, the presented work evaluates several available expressions for hindered settling based on long-term batch settling data. Specific attention is paid to the behaviour of these hindered settling functions in the compression region in order to evaluate how the modelling of sludge compression is influenced by the choice of a certain hindered settling function. The analysis shows that the exponential hindered settling forms, which are most commonly used in traditional SST models, not only account for hindered settling but partly lump other phenomena (compression) as well. This makes them unsuitable for advanced 1-D models that explicitly include each phenomenon in a modular way. A power-law function is shown to be more appropriate to describe the hindered settling velocity in advanced 1-D SST models.
Cryogenic Fuel Tank Draining Analysis Model
NASA Technical Reports Server (NTRS)
Greer, Donald
1999-01-01
One of the technological challenges in designing advanced hypersonic aircraft and the next generation of spacecraft is developing reusable flight-weight cryogenic fuel tanks. As an aid in the design and analysis of these cryogenic tanks, a computational fluid dynamics (CFD) model has been developed specifically for the analysis of flow in a cryogenic fuel tank. This model employs the full set of Navier-Stokes equations, except that viscous dissipation is neglected in the energy equation. An explicit finite difference technique in two-dimensional generalized coordinates, approximated to second-order accuracy in both space and time is used. The stiffness resulting from the low Mach number is resolved by using artificial compressibility. The model simulates the transient, two-dimensional draining of a fuel tank cross section. To calculate the slosh wave dynamics the interface between the ullage gas and liquid fuel is modeled as a free surface. Then, experimental data for free convection inside a horizontal cylinder are compared with model results. Finally, cryogenic tank draining calculations are performed with three different wall heat fluxes to demonstrate the effect of wall heat flux on the internal tank flow field.
Erosion Modeling Analysis for SME Tank Cavity
LEE, SI
2004-05-03
Previous computational work to evaluate erosion in the DWPF Slurry Mix Evaporator vessel has been extended to address the potential for the erosion to accelerate because of changes to the tank bottom profile. The same erosion mechanism identified in the previous work, abrasive erosion driven by high wall shear stress, was applied to the current evaluation. The current work extends the previous analysis by incorporating the observed changes to the tank bottom and coil support structure in the vicinity of the coil guides. The results show that wall shear on the tank bottom is about the same magnitude as found in previous results. Shear stresses in the eroded cavities are reduced compared to those that caused the initial erosion to the extent that anticipated continued erosion of those locations is minimal. If SR operations were continued at an agitator speed of 130 rpm, the edge of the existing eroded cavities would probably smooth out, while the rate of erosion at the bottom of the cavity would decrease significantly with time. Further, reducing the agitator speed to 103 rpm will reduce shear stresses throughout the bottom region of the tank enough to essentially preclude any significant continued erosion. Because this report is an extension to previously documented work, most background information has been omitted. A complete discussion of the motivation for both the analysis and the modeling is provided in Lee et al., ''Erosion Modeling Analysis for Modified DWPF SR Tank''.
Quasi 1D Modeling of Mixed Compression Supersonic Inlets
NASA Technical Reports Server (NTRS)
Kopasakis, George; Connolly, Joseph W.; Paxson, Daniel E.; Woolwine, Kyle J.
2012-01-01
The AeroServoElasticity task under the NASA Supersonics Project is developing dynamic models of the propulsion system and the vehicle in order to conduct research for integrated vehicle dynamic performance. As part of this effort, a nonlinear quasi 1-dimensional model of the 2-dimensional bifurcated mixed compression supersonic inlet is being developed. The model utilizes computational fluid dynamics for both the supersonic and subsonic diffusers. The oblique shocks are modeled utilizing compressible flow equations. This model also implements variable geometry required to control the normal shock position. The model is flexible and can also be utilized to simulate other mixed compression supersonic inlet designs. The model was validated both in time and in the frequency domain against the legacy LArge Perturbation INlet code, which has been previously verified using test data. This legacy code written in FORTRAN is quite extensive and complex in terms of the amount of software and number of subroutines. Further, the legacy code is not suitable for closed loop feedback controls design, and the simulation environment is not amenable to systems integration. Therefore, a solution is to develop an innovative, more simplified, mixed compression inlet model with the same steady state and dynamic performance as the legacy code that also can be used for controls design. The new nonlinear dynamic model is implemented in MATLAB Simulink. This environment allows easier development of linear models for controls design for shock positioning. The new model is also well suited for integration with a propulsion system model to study inlet/propulsion system performance, and integration with an aero-servo-elastic system model to study integrated vehicle ride quality, vehicle stability, and efficiency.
1-D Radiative-Convective Model for Terrestrial Exoplanet Atmospheres
NASA Astrophysics Data System (ADS)
Leung, Cecilia W. S.; Robinson, Tyler D.
2016-10-01
We present a one dimensional radiative-convective model to study the thermal structure of terrestrial exoplanetary atmospheres. The radiative transfer and equilibrium chemistry in our model is based on similar methodologies in models used for studying Extrasolar Giant Planets (Fortney et al. 2005b.) We validated our model in the optically thin and thick limits, and compared our pressure-temperature profiles against the analytical solutions of Robinson & Catling (2012). For extrasolar terrestrial planets with pure hydrogen atmospheres, we evaluated the effects of H2-H2 collision induced absorption and identified the purely roto-translational band in our modeled spectra. We also examined how enhanced atmospheric metallicities affect the temperature structure, chemistry, and spectra of terrestrial exoplanets. For a terrestrial extrasolar planet whose atmospheric compostion is 100 times solar orbiting a sun-like star at 2 AU, our model resulted in a reducing atmosphere with H2O, CH4, and NH3 as the dominant greenhouse gases.
Validation of 1-D transport and sawtooth models for ITER
Connor, J.W.; Turner, M.F.; Attenberger, S.E.; Houlberg, W.A.
1996-12-31
In this paper the authors describe progress on validating a number of local transport models by comparing their predictions with relevant experimental data from a range of tokamaks in the ITER profile database. This database, the testing procedure and results are discussed. In addition a model for sawtooth oscillations is used to investigate their effect in an ITER plasma with alpha-particles.
Kinetic and Stochastic Models of 1D yeast ``prions"
NASA Astrophysics Data System (ADS)
Kunes, Kay
2005-03-01
Mammalian prion proteins (PrP) are of public health interest because of mad cow and chronic wasting diseases. Yeasts have proteins, which can undergo similar reconformation and aggregation processes to PrP; yeast ``prions" are simpler to experimentally study and model. Recent in vitro studies of the SUP35 protein (1), showed long aggregates and pure exponential growth of the misfolded form. To explain this data, we have extended a previous model of aggregation kinetics along with our own stochastic approach (2). Both models assume reconformation only upon aggregation, and include aggregate fissioning and an initial nucleation barrier. We find for sufficiently small nucleation rates or seeding by small dimer concentrations that we can achieve the requisite exponential growth and long aggregates.
Kinetic Model for 1D aggregation of yeast ``prions''
NASA Astrophysics Data System (ADS)
Kunes, Kay; Cox, Daniel; Singh, Rajiv
2004-03-01
Mammalian prion proteins (PrP) are of public health interest because of mad cow and chronic wasting diseases. Yeast have proteins which can undergo similar reconformation and aggregation processes to PrP; yeast forms are simpler to experimentally study and model. Recent in vitro studies of the SUP35 protein(1), showed long aggregates and pure exponential growth of the misfolded form. To explain this data, we have extended a previous model of aggregation kinetics(2). The model assumes reconformation only upon aggregation, and includes aggregate fissioning and an initial nucleation barrier. We find for sufficiently small nucleation rates or seeding by small dimer concentrations that we can achieve the requisite exponential growth and long aggregates. We will compare to a more realistic stochastic kinetics model and present prelimary attempts to describe recent experiments on SUP35 strains. *-Supported by U.S. Army Congressionally Mandated Research Fund. 1) P. Chien and J.S. Weissman, Nature 410, 223 (2001); http://online.kitp.ucsb.edu/online/bionet03/collins/. 2) J. Masel, V.A.> Jansen, M.A. Nowak, Biophys. Chem. 77, 139 (1999).
Computer modeling of ORNL storage tank sludge mobilization and mixing
Terrones, G.; Eyler, L.L.
1993-09-01
This report presents and analyzes the results of the computer modeling of mixing and mobilization of sludge in horizontal, cylindrical storage tanks using submerged liquid jets. The computer modeling uses the TEMPEST computational fluid dynamics computer program. The horizontal, cylindrical storage tank configuration is similar to the Melton Valley Storage Tanks (MVST) at Oak Ridge National (ORNL). The MVST tank contents exhibit non-homogeneous, non-Newtonian rheology characteristics. The eventual goals of the simulations are to determine under what conditions sludge mobilization using submerged liquid jets is feasible in tanks of this configuration, and to estimate mixing times required to approach homogeneity of the contents of the tanks.
GEOCHEMICAL TESTING AND MODEL DEVELOPMENT - RESIDUAL TANK WASTE TEST PLAN
CANTRELL KJ; CONNELLY MP
2010-03-09
This Test Plan describes the testing and chemical analyses release rate studies on tank residual samples collected following the retrieval of waste from the tank. This work will provide the data required to develop a contaminant release model for the tank residuals from both sludge and salt cake single-shell tanks. The data are intended for use in the long-term performance assessment and conceptual model development.
GaAs solar cell photoresponse modeling using PC-1D V2.1
NASA Technical Reports Server (NTRS)
Huber, D. A.; Olsen, L. C.; Dunham, G.; Addis, F. W.
1991-01-01
Photoresponse data of high efficiency GaAs solar cells were analyzed using PC-1D V2.1. The approach required to use PC-1D for photoresponse data analysis, and the physical insights gained from performing the analysis are discussed. In particular, the effect of Al(x)Ga(1-x)As heteroface quality was modeled. Photoresponse or spectral quantum efficiency is an important tool in characterizing material quality and predicting cell performance. The strength of the photoresponse measurement lies in the ability to precisely fit the experimental data with a physical model. PC-1D provides a flexible platform for calculations based on these physical models.
Development of an energy storage tank model
NASA Astrophysics Data System (ADS)
Buckley, Robert Christopher
A linearized, one-dimensional finite difference model employing an implicit finite difference method for energy storage tanks is developed, programmed with MATLAB, and demonstrated for different applications. A set of nodal energy equations is developed by considering the energy interactions on a small control volume. The general method of solving these equations is described as are other features of the simulation program. Two modeling applications are presented: the first using a hot water storage tank with a solar collector and an absorption chiller to cool a building in the summer, the second using a molten salt storage system with a solar collector and steam power plant to generate electricity. Recommendations for further study as well as all of the source code generated in the project are also provided.
Potent neutralizing anti-CD1d antibody reduces lung cytokine release in primate asthma model
Nambiar, Jonathan; Clarke, Adam W; Shim, Doris; Mabon, David; Tian, Chen; Windloch, Karolina; Buhmann, Chris; Corazon, Beau; Lindgren, Matilda; Pollard, Matthew; Domagala, Teresa; Poulton, Lynn; Doyle, Anthony G
2015-01-01
CD1d is a receptor on antigen-presenting cells involved in triggering cell populations, particularly natural killer T (NKT) cells, to release high levels of cytokines. NKT cells are implicated in asthma pathology and blockade of the CD1d/NKT cell pathway may have therapeutic potential. We developed a potent anti-human CD1d antibody (NIB.2) that possesses high affinity for human and cynomolgus macaque CD1d (KD ∼100 pM) and strong neutralizing activity in human primary cell-based assays (IC50 typically <100 pM). By epitope mapping experiments, we showed that NIB.2 binds to CD1d in close proximity to the interface of CD1d and the Type 1 NKT cell receptor β-chain. Together with data showing that NIB.2 inhibited stimulation via CD1d loaded with different glycolipids, this supports a mechanism whereby NIB.2 inhibits NKT cell activation by inhibiting Type 1 NKT cell receptor β-chain interactions with CD1d, independent of the lipid antigen in the CD1d antigen-binding cleft. The strong in vitro potency of NIB.2 was reflected in vivo in an Ascaris suum cynomolgus macaque asthma model. Compared with vehicle control, NIB.2 treatment significantly reduced bronchoalveolar lavage (BAL) levels of Ascaris-induced cytokines IL-5, IL-8 and IL-1 receptor antagonist, and significantly reduced baseline levels of GM-CSF, IL-6, IL-15, IL-12/23p40, MIP-1α, MIP-1β, and VEGF. At a cellular population level NIB.2 also reduced numbers of BAL lymphocytes and macrophages, and blood eosinophils and basophils. We demonstrate that anti-CD1d antibody blockade of the CD1d/NKT pathway modulates inflammatory parameters in vivo in a primate inflammation model, with therapeutic potential for diseases where the local cytokine milieu is critical. PMID:25751125
Potent neutralizing anti-CD1d antibody reduces lung cytokine release in primate asthma model.
Nambiar, Jonathan; Clarke, Adam W; Shim, Doris; Mabon, David; Tian, Chen; Windloch, Karolina; Buhmann, Chris; Corazon, Beau; Lindgren, Matilda; Pollard, Matthew; Domagala, Teresa; Poulton, Lynn; Doyle, Anthony G
2015-01-01
CD1d is a receptor on antigen-presenting cells involved in triggering cell populations, particularly natural killer T (NKT) cells, to release high levels of cytokines. NKT cells are implicated in asthma pathology and blockade of the CD1d/NKT cell pathway may have therapeutic potential. We developed a potent anti-human CD1d antibody (NIB.2) that possesses high affinity for human and cynomolgus macaque CD1d (KD ∼100 pM) and strong neutralizing activity in human primary cell-based assays (IC50 typically <100 pM). By epitope mapping experiments, we showed that NIB.2 binds to CD1d in close proximity to the interface of CD1d and the Type 1 NKT cell receptor β-chain. Together with data showing that NIB.2 inhibited stimulation via CD1d loaded with different glycolipids, this supports a mechanism whereby NIB.2 inhibits NKT cell activation by inhibiting Type 1 NKT cell receptor β-chain interactions with CD1d, independent of the lipid antigen in the CD1d antigen-binding cleft. The strong in vitro potency of NIB.2 was reflected in vivo in an Ascaris suum cynomolgus macaque asthma model. Compared with vehicle control, NIB.2 treatment significantly reduced bronchoalveolar lavage (BAL) levels of Ascaris-induced cytokines IL-5, IL-8 and IL-1 receptor antagonist, and significantly reduced baseline levels of GM-CSF, IL-6, IL-15, IL-12/23p40, MIP-1α, MIP-1β, and VEGF. At a cellular population level NIB.2 also reduced numbers of BAL lymphocytes and macrophages, and blood eosinophils and basophils. We demonstrate that anti-CD1d antibody blockade of the CD1d/NKT pathway modulates inflammatory parameters in vivo in a primate inflammation model, with therapeutic potential for diseases where the local cytokine milieu is critical.
Modeling analysis for grout hopper waste tank
Lee, S. Y.; Ryans, J. M.
2012-07-01
The Saltstone facility at Savannah River Site (SRS) has a grout hopper tank to provide agitator stirring of the Saltstone feed materials. The tank has about 300 gallon capacity to provide a larger working volume for the grout nuclear waste slurry to be held in case of a process upset, and it is equipped with a mechanical agitator, which is intended to keep the grout in motion and agitated so that it won't start to set up. The primary objective of the work was to evaluate the flow performance for mechanical agitators to keep an adequate stirring of the feed materials and to estimate an agitator speed which provides acceptable flow performance with a 45 deg. pitched four-blade agitator. In addition, the power consumption required for the agitator operation was estimated. The modeling calculations were performed by taking two steps of the Computational Fluid Dynamics (CFD) modeling approach. A series of sensitivity calculations for different designs of agitators and operating conditions have been performed to investigate the impact of key parameters on the grout hydraulic performance in a 300-gallon hopper tank. Recommended operational guidance was developed by using the basic concept that local shear rates and flow patterns can be used as a measure of hydraulic performance and spatial stirring. Flow patterns and fluid residence time were estimated by a Lagrangian integration technique along the flow paths from the material feed inlet. (authors)
NASA Astrophysics Data System (ADS)
Lei, Wang; Yanzhong, Li; Kang, Zhu; Yonghua, Jin
2015-01-01
In order to select an effective approach to predict the pressurization characteristics of cryogenic tank during rocket launching, three computational models, defined as 0-D, 1-D and CFD models, are used to obtain the pressure evolution and thermal performance of a cryogenic tank during pressurized discharge period. Several pressurization cases are computed by all of the three models to evaluate their predictive abilities and effects, respectively. The comparative study shows that for the case with a diffuser-type injector at the tank inlet, the consistent results by the three models are obtained in the most of period, except that 1-D model has a peak departure prediction of pressure value at the beginning of process. All of the three models can be used to predict the pressurization performance, and their predictive abilities could be validated with one another. The CFD model is the unique suitable model to display the pressurization performance including physical distribution in radial direction especially for the system with no-diffuser-type injector. Based on the analysis, the application selection of three models for different cases is accomplished. The 0-D model is the priority selection for a simple pressure prediction of tank ullage, even for the situation that severe temperature distribution exists in the ullage range. The 1-D model is the optimal selection as considering both the convenience and the time consumption for the constant-pressure cases. But it is not recommended in a constant-inlet flux cases for its distinct predicting deviation at the beginning of the process. When the detailed distributions within the tank are concerned, the CFD model is the unique selection. The results of this paper may be beneficial to the model selection and optimization analysis of a pressurization system.
ANSYS PARAMETRIC MODEL FOR TANK DST-AY
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This report documents the parametric ANSYS models developed for dome load analyses of double-shell tanks. The default model parameters are specific to the AY tanks but can be easily modified for tank-specific analysis of AN, AW, AP, AZ or SY tanks. Both axisymmetric slice and full 360 degree models are provided. The purpose of this calculation is to develop a parametric finite element analysis model of the Hanford Site underground waste storage tanks. This is not an analysis. Instead, the present calculation develops a parametric model of the double shell tank DST-AY, which is based on Buyer-supplied as-built drawings and information for the analyses of record (AOR) for Double-Shell Tanks (DSTs), encompassing the existing tank load conditions. The computer model has various parameters that can be either changed directly or easily added by a knowledgeable ANSYS user. These parameters are modified to consider field conditions, such as in-situ wall thickness of primary steel tank, dead and live loads, moving loads, berm loads, soil overburden depth plus surrounding soil, internal waste level and waste specific gravity, internal vapor pressure, and thermal loads within the tank. This document contains sample calculations that demonstrate how various aspects of the parametric model function. These sample calculations in this document are not to be used for assessing the structural integrity of the DST-AY tanks at the Hanford Site.
Benchmarks and models for 1-D radiation transport in stochastic participating media
Miller, David Scott
2000-08-01
Benchmark calculations for radiation transport coupled to a material temperature equation in a 1-D slab and 1-D spherical geometry binary random media are presented. The mixing statistics are taken to be homogeneous Markov statistics in the 1-D slab but only approximately Markov statistics in the 1-D sphere. The material chunk sizes are described by Poisson distribution functions. The material opacities are first taken to be constant and then allowed to vary as a strong function of material temperature. Benchmark values and variances for time evolution of the ensemble average of material temperature energy density and radiation transmission are computed via a Monte Carlo type method. These benchmarks are used as a basis for comparison with three other approximate methods of solution. One of these approximate methods is simple atomic mix. The second approximate model is an adaptation of what is commonly called the Levermore-Pomraning model and which is referred to here as the standard model. It is shown that recasting the temperature coupling as a type of effective scattering can be useful in formulating the third approximate model, an adaptation of a model due to Su and Pomraning which attempts to account for the effects of scattering in a stochastic context. This last adaptation shows consistent improvement over both the atomic mix and standard models when used in the 1-D slab geometry but shows limited improvement in the 1-D spherical geometry. Benchmark values are also computed for radiation transmission from the 1-D sphere without material heating present. This is to evaluate the performance of the standard model on this geometry--something which has never been done before. All of the various tests demonstrate the importance of stochastic structure on the solution. Also demonstrated are the range of usefulness and limitations of a simple atomic mix formulation.
Benchmarks and models for 1-D radiation transport in stochastic participating media
NASA Astrophysics Data System (ADS)
Miller, David Scott
Benchmark calculations for radiation transport coupled to a material temperature equation in a 1-D slab and 1-D spherical geometry binary random media are presented. The mixing statistics are taken to be homogeneous Markov statistics in the 1-D slab but only approximately Markov statistics in the 1-D sphere. The material chunk sizes are described by Poisson distribution functions. The material opacities are first taken to be constant and then allowed to vary as a strong function of material temperature. Benchmark values and variances for time evolution of the ensemble average of material temperature energy density and radiation transmission are computed via a Monte Carlo type method. These benchmarks are used as a basis for comparison with three other approximate methods of solution. One of these approximate methods is simple atomic mix. The second approximate model is an adaptation of what is commonly called the Levermore-Pomraning model and which is referred to here as the standard model. It is shown that recasting the temperature coupling as a type of effective scattering can be useful in formulating the third approximate model, an adaptation of a model due to Su and Pomraning which attempts to account for the effects of scattering in a stochastic context. This last adaptation shows consistent improvement over both the atomic mix and standard models when used in the 1-D slab geometry but shows limited improvement in the 1-D spherical geometry. Benchmark values are also computed for radiation transmission from the 1-D sphere without material heating present. This is to evaluate the performance of the standard model on this geometry-something which has never been done before. All of the various tests demonstrate the importance of stochastic structure on the solution. Also demonstrated are the range of usefulness and limitations of a simple atomic mix formulation.
MODELING ANALYSIS FOR GROUT HOPPER WASTE TANK
Lee, S.
2012-01-04
The Saltstone facility at Savannah River Site (SRS) has a grout hopper tank to provide agitator stirring of the Saltstone feed materials. The tank has about 300 gallon capacity to provide a larger working volume for the grout nuclear waste slurry to be held in case of a process upset, and it is equipped with a mechanical agitator, which is intended to keep the grout in motion and agitated so that it won't start to set up. The primary objective of the work was to evaluate the flow performance for mechanical agitators to prevent vortex pull-through for an adequate stirring of the feed materials and to estimate an agitator speed which provides acceptable flow performance with a 45{sup o} pitched four-blade agitator. In addition, the power consumption required for the agitator operation was estimated. The modeling calculations were performed by taking two steps of the Computational Fluid Dynamics (CFD) modeling approach. As a first step, a simple single-stage agitator model with 45{sup o} pitched propeller blades was developed for the initial scoping analysis of the flow pattern behaviors for a range of different operating conditions. Based on the initial phase-1 results, the phase-2 model with a two-stage agitator was developed for the final performance evaluations. A series of sensitivity calculations for different designs of agitators and operating conditions have been performed to investigate the impact of key parameters on the grout hydraulic performance in a 300-gallon hopper tank. For the analysis, viscous shear was modeled by using the Bingham plastic approximation. Steady state analyses with a two-equation turbulence model were performed. All analyses were based on three-dimensional results. Recommended operational guidance was developed by using the basic concept that local shear rate profiles and flow patterns can be used as a measure of hydraulic performance and spatial stirring. Flow patterns were estimated by a Lagrangian integration technique along the
Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes
Johnson, Raymond H.; Morrison, Stan; Morris, Sarah; Tigar, Aaron; Dam, William; Dayvault, Jalena
2016-04-26
Motivation for Study: Natural flushing of contaminants at various U.S. Department of Energy Office of Legacy Management sites is not proceeding as quickly as predicted (plume persistence) Objectives: Help determine natural flushing rates using column tests. Use 1D reactive transport modeling to better understand the major processes that are creating plume persistence Approach: Core samples from under a former mill tailings area Tailings have been removed. Column leaching using lab-prepared water similar to nearby Gunnison River water. 1D reactive transport modeling to evaluate processes
A versatile compact model for ballistic 1D transistor: GNRFET and CNTFET comparison
NASA Astrophysics Data System (ADS)
Frégonèse, Sébastien; Maneux, Cristell; Zimmer, Thomas
2010-11-01
This paper presents a versatile compact model dedicated to 1D transistors in order to predict the ultimate performances of nano-device-based circuits. We have developed a thermionic charge model based on the non-parabolic-energy-dispersion-relation NPEDR. The model is valid for both CNTFET and GNRFET. Model results are compared with GNRFET NEGF simulations. Then, GNRFET and CNTFET performances are analysed through two circuit demonstrators such as a ring oscillator circuit and 6T RAM.
Appraisal of chlorine contact tank modelling practices.
Rauen, William B; Angeloudis, Athanasios; Falconer, Roger A
2012-11-15
With new water directives imposing strict regulations to reduce the footprint of treatment operations and contaminant levels, a performance review of water treatment facilities, including Chlorine Contact Tanks (CCTs) is required. This paper includes a critical appraisal of the international literature on CCT modelling practices to date, aiming to assist the identification of areas requiring further development, in particular, relating to the computational modelling capability and availability of tools to assist hydraulic design and optimisation studies of CCTs. It notes that the hydraulic optimisation practice of poorly designed tanks commenced with experimental studies undertaken in the 1960s and 1970s, which involved mainly two types of studies, namely in situ tracer tests and laboratory physical modelling. The former has traditionally been conducted to diagnose the hydraulic performance of existing CCTs, typically based on results such as Residence Time Distribution (RTD) curves and values of the Hydraulic Efficiency Indicators (HEIs). The latter has been useful in trial and error testing of the impact of certain design modifications on those results, with suggestions for later improvements of the field scale unit. In the 1980s mathematical and numerical modelling studies started to be used to assist CCT investigations, offering a greater level of detail in a more cost-effective manner than equivalent experimentally based investigations. With the growth of computing power and the popularisation of computational models, the 1990s saw the development and application of Computational Fluid Dynamics (CFD) tools to simulate the hydraulic performance of CCTs, sometimes independently of experimentation, other than by using available data to calibrate and validate modelling predictions. This has led to the current scenario of CFD models being invaluable assistive tools in optimisation studies of CCTs, with the experimentation practice continuing to allow for specific
Adaptive Model of Wastewater Aeration Tank
NASA Astrophysics Data System (ADS)
Sniders, Andris; Laizans, Aigars
2011-01-01
The paper discusses the methodology of oxygen transfer virtual simulation in a wastewater biological treatment process, using the MATLAB/SIMULINK technology. A self-tuning adaptive model of a wastewater aeration tank, as a non-stationary object, with variable time dependent sensitivity and inertia indexes, as the functions of input variable - air pneumatic supply capacity Lg(t) (m3/min), output variable - dissolved oxygen concentration C(t) (g/m3) and oxygen expenditure, as a load - q(t) (g/min), required for wastewater complete purification, is expounded. Virtual models, applying Laplace transforms and SIMULINK blocks library, are composed in order to compare the transient processes of dissolved oxygen concentration in the simplified stationary model with constant sensitivity and inertia coefficients, and in the non-stationary model with variable sensitivity and inertia indexes. The simulation block-diagram for non-stationary model adoption to the variable parameters is developed, using informative links from input variable Lg(t), from variable load q(t) and feedback from output variable C(t) as inputs of calculation modulus, allowing to instantly re-calculate the variable indexes during simulation time. Comparison of the simplified stationary model and the non-stationary model shows that the simulation results of oxygen transfer differ up to 50%.
Accuracy of 1D microvascular flow models in the limit of low Reynolds numbers.
Pindera, Maciej Z; Ding, Hui; Athavale, Mahesh M; Chen, Zhijian
2009-05-01
We describe results of numerical simulations of steady flows in tubes with branch bifurcations using fully 3D and reduced 1D geometries. The intent is to delineate the range of validity of reduced models used for simulations of flows in microcapillary networks, as a function of the flow Reynolds number Re. Results from model problems indicate that for Re less than 1 and possibly as high as 10, vasculatures may be represented by strictly 1D Poiseuille flow geometries with flow variation in the axial dimensions only. In that range flow rate predictions in the different branches generated by 1D and 3D models differ by a constant factor, independent of Re. When the cross-sectional areas of the branches are constant these differences are generally small and appear to stem from an uncertainty of how the individual branch lengths are defined. This uncertainty can be accounted for by a simple geometrical correction. For non-constant cross-sections the differences can be much more significant. If additional corrections for the presence of branch junctions and flow area variations are not taken into account in 1D models of complex vasculatures, the resultant flow predictions should be interpreted with caution.
Interfacing the NRL 1-D High Vertical Resolution Aerosol Model with COAMPS
2016-06-13
TERM GOALS Identify, understand and quantify all the physical processes that govern the aerosols in the marine environment and develop a...size and composition distributions are required. Many of the aerosol source, sink and transformation processes are highly dependent on meteorological...parameters such as wind speed, humidity profile, clouds, precipitation scavenging, etc. The NRL 1-D aerosol- processes model includes all these
HYDRUS-1D Modeling of an Irrigated Agricultural Plot with Application to Aquifer Recharge Estimation
Technology Transfer Automated Retrieval System (TEKTRAN)
A variety of methods are available for estimating aquifer recharge in semi-arid regions, each with advantages and disadvantages. We are investigating a procedure for estimating recharge in an irrigated basin. The method involves computing irrigation return flows based on HYDRUS-1D modeling of root z...
TRANSIENT HEAT TRANSFER MODEL FOR SRS WASTE TANK OPERATIONS
Lee, S; Richard Dimenna, R
2007-03-27
A transient heat balance model was developed to assess the impact of a Submersible Mixer Pump (SMP) on waste temperature during the process of waste mixing and removal for the Type-I Savannah River Site (SRS) tanks. The model results will be mainly used to determine the SMP design impacts on the waste tank temperature during operations and to develop a specification for a new SMP design to replace existing long-shaft mixer pumps used during waste removal. The model will also be used to provide input to the operation planning. This planning will be used as input to pump run duration in order to maintain temperature requirements within the tank during SMP operation. The analysis model took a parametric approach. A series of the modeling analyses was performed to examine how submersible mixer pumps affect tank temperature during waste removal operation in the Type-I tank. The model domain included radioactive decay heat load, two SMP's, and one Submersible Transfer Pump (STP) as heat source terms. The present model was benchmarked against the test data obtained by the tank measurement to examine the quantitative thermal response of the tank and to establish the reference conditions of the operating variables under no SMP operation. The results showed that the model predictions agreed with the test data of the waste temperatures within about 10%. Transient modeling calculations for two potential scenarios of sludge mixing and removal operations have been made to estimate transient waste temperatures within a Type-I waste tank. When two 200-HP submersible mixers and 12 active cooling coils are continuously operated in 100-in tank level and 40 C initial temperature for 40 days since the initiation of mixing operation, waste temperature rises about 9 C in 48 hours at a maximum. Sensitivity studies for the key operating variables were performed. The sensitivity results showed that the chromate cooling coil system provided the primary cooling mechanism to remove process
Review of Zero-D and 1-D Models of Blood Flow in the Cardiovascular System
2011-01-01
Background Zero-dimensional (lumped parameter) and one dimensional models, based on simplified representations of the components of the cardiovascular system, can contribute strongly to our understanding of circulatory physiology. Zero-D models provide a concise way to evaluate the haemodynamic interactions among the cardiovascular organs, whilst one-D (distributed parameter) models add the facility to represent efficiently the effects of pulse wave transmission in the arterial network at greatly reduced computational expense compared to higher dimensional computational fluid dynamics studies. There is extensive literature on both types of models. Method and Results The purpose of this review article is to summarise published 0D and 1D models of the cardiovascular system, to explore their limitations and range of application, and to provide an indication of the physiological phenomena that can be included in these representations. The review on 0D models collects together in one place a description of the range of models that have been used to describe the various characteristics of cardiovascular response, together with the factors that influence it. Such models generally feature the major components of the system, such as the heart, the heart valves and the vasculature. The models are categorised in terms of the features of the system that they are able to represent, their complexity and range of application: representations of effects including pressure-dependent vessel properties, interaction between the heart chambers, neuro-regulation and auto-regulation are explored. The examination on 1D models covers various methods for the assembly, discretisation and solution of the governing equations, in conjunction with a report of the definition and treatment of boundary conditions. Increasingly, 0D and 1D models are used in multi-scale models, in which their primary role is to provide boundary conditions for sophisticate, and often patient-specific, 2D and 3D models
Constraint on the 1D earth model near core-mantle boundary by free core nutation
NASA Astrophysics Data System (ADS)
Huang, Chengli; Zhang, Mian
2015-04-01
Free core nutation (FCN) is a normal mode of the rotating earth with fluid outer core (FOC). Its period depends on the physics of the mantle and FOC, especially the parameters near core-mantle boundary (CMB), like the density and elastic (Lame) parameters. FCN period can be determined very accurately by VLBI and superconductive tidal gravimetry, but the theoretical calculation results of FCN period from traditional approaches and 1D earth model (like PREM) deviate significantly from the accurate observation. Meanwhile, the influence of the uncertainty of a given earth model on nutation has never been studied before. In this work, a numerical experiment is presented to check this problem, and we want to see whether FCN can provide a constraint on the construction of a 1D earth model, especially on the gradient of material density near CMB.
Tank bromeliad - a natural model ecosystem for methane cycling research
NASA Astrophysics Data System (ADS)
Martinson, Guntars; Brandt, Franziska; Conrad, Ralf
2014-05-01
Tank bromeliads are common epiphytes throughout neotropical forest ecosystems. They are relatively small discrete habitats for terrestrial and aquatic macro- and microorganisms and naturally replicated. Their tanks effectively collect leaf litter and water and harbor a diverse microbial community. Up to several thousands of these tank bromeliads per hectare of tropical forest create a unique wetland ecosystem responsible for significant methane emissions. In a field study in tropical montane forests of southern Ecuador we sampled tank bromeliads of different species, size and canopy height and found that tank water availability controlled community composition of methanogenic archaea, determined by molecular analysis of the archaeal 16S rRNA genes. We set up a greenhouse experiment to investigate drying and re-wetting effects on microbial community composition and methanogenesis. Additionally, we conducted 13-CH-4 and 13-CO-2 labeling studies to investigate potential interaction of plant and microbial metabolism during methane cycling in tank bromeliads. Drying resulted in rapid change of the microbial community composition. The relative abundance of acetoclastic methanogens increased and that of hydrogenotrophic methanogens decreased with decreasing tank water availability confirming our field observations. Labeling studies showed that carbon was released from the plant into the tank supporting methanogenesis and that tank-produced methane was ventilated through the bromeliad leaf structure into the atmosphere which is analogous to the rhizosphere environment of wetland ecosystems. The bromeliad ecosystem may therefore provide a natural model to study how environmental changes and plant-microbe interactions drive methane cycling in aquatic-terrestrial ecosystems.
Thermodynamic nature of vitrification in a 1D model of a structural glass former
Semenov, A. N.
2015-07-28
We propose a new spin-glass model with no positional quenched disorder which is regarded as a coarse-grained model of a structural glass-former. The model is analyzed in the 1D case when the number N of states of a primary cell is large. For N → ∞, the model exhibits a sharp freezing transition of the thermodynamic origin. It is shown both analytically and numerically that the glass transition is accompanied by a significant growth of a static length scale ξ pointing to the structural (equilibrium) nature of dynamical slowdown effects in supercooled liquids.
SILVA: EDF two-phase 1D annular model of a CFB boiler furnace
Montat, D.; Fauquet, P.; Lafanechere, L.; Bursi, J.M.
1997-12-31
Aiming to improve its knowledge of CFB boilers, EDF has initiated a R and D program including: laboratory work on mock-ups, numerical modelling and on-site tests in CFB power plants. One of the objectives of this program is the development of a comprehensive steady-state 1D model of the solid circulation loop, named SILVA, for plant operation and design evaluation purposes. This paper describes its mathematical and physical modelling. Promising validation of the model on cold mock-up and industrial CFB is presented.
Thermodynamic nature of vitrification in a 1D model of a structural glass former
NASA Astrophysics Data System (ADS)
Semenov, A. N.
2015-07-01
We propose a new spin-glass model with no positional quenched disorder which is regarded as a coarse-grained model of a structural glass-former. The model is analyzed in the 1D case when the number N of states of a primary cell is large. For N → ∞, the model exhibits a sharp freezing transition of the thermodynamic origin. It is shown both analytically and numerically that the glass transition is accompanied by a significant growth of a static length scale ξ pointing to the structural (equilibrium) nature of dynamical slowdown effects in supercooled liquids.
Thermodynamic nature of vitrification in a 1D model of a structural glass former.
Semenov, A N
2015-07-28
We propose a new spin-glass model with no positional quenched disorder which is regarded as a coarse-grained model of a structural glass-former. The model is analyzed in the 1D case when the number N of states of a primary cell is large. For N → ∞, the model exhibits a sharp freezing transition of the thermodynamic origin. It is shown both analytically and numerically that the glass transition is accompanied by a significant growth of a static length scale ξ pointing to the structural (equilibrium) nature of dynamical slowdown effects in supercooled liquids.
Density matrix spectra and order parameters in the 1D extended Hubbard model
NASA Astrophysics Data System (ADS)
Yu, Wing Chi; Gu, Shi-Jian; Lin, Hai-Qing
2016-09-01
Without any knowledge of the symmetry existing in a system, we derive the exact forms of the order parameters which show long-range correlations in the ground state of the one-dimensional (1D) extended Hubbard model using a quantum information approach. Our work demonstrates that the quantum information approach can help us to find the explicit form of the order parameter, which could not be derived systematically via traditional methods in the condensed matter theory.
Box model and 1D longitudinal model of flow and transport in Bosten Lake, China
NASA Astrophysics Data System (ADS)
Li, Ning; Kinzelbach, Wolfgang; Li, WenPeng; Dong, XinGuang
2015-05-01
Bosten Lake in the southeast of Yanqi Catchment, China, supports the downstream agricultural and natural environments. Over the last few decades the intensive agricultural activities in Yanqi Catchment resulted in decreased lake levels and deteriorated lake water quality. A two-box model is constructed to understand the evolution of lake level and salinity between 1958 and 2008. The two-box model of the lake indicates that the evaporation does have the same trend as the observed lake area and the annual average evaporation agrees with the value obtained from the Penman-Monteith approach. To achieve a correct salt balance, the ratio of outflow concentration and average lake concentration has to be around 0.7. This is due to the incomplete mixing of the lake caused by short-circuiting between tributary inflow and the main outflow via the pump stations abstracting water from the lake. This short-circuiting is investigated in more detail by a 1D numerical flow and transport model of the lake calibrated with observations of lake level and lake concentrations. The distributed model reproduces the correct time-varying outflow concentration. It is used for the assessment of two basic management options: increasing river discharge (by water saving irrigation, reduction of phreatic evaporation or reduction of agricultural area) and diverting saline drainage water to the desert. Increasing river discharge to the lake by 20% reduces the east basin salt concentration by 0.55 kg/m3, while capturing all the drainage water and discharging it to depressions instead of the lake reduces the east basin salt concentration by 0.63 kg/m3. A combination of increasing river inflow and decreasing drainage salt flux is sufficient to bring future lake TDS below the required 1 kg/m3, to keep a lake level that sustains the lake ecosystem, and to supply more water for downstream development and ecosystem rehabilitation.
A Systematic Comparison between 1-D and 3-D Hemodynamics in Compliant Arterial Models
Xiao, Nan; Alastruey, Jordi; Figueroa, C. Alberto
2015-01-01
SUMMARY In this article, we present a systematic comparison of computational hemodynamics in arterial models with deformable vessel walls using a one-dimensional (1-D) and a three-dimensional (3-D) method. The simulations were performed using a series of idealized compliant arterial models representing the common carotid artery, thoracic aorta, aortic bifurcation, and full aorta from the arch to the iliac bifurcation. The formulations share identical outflow boundary conditions and have compatible material laws. We also present an iterative algorithm to select the parameters for the outflow boundary conditions using the 1-D theory to achieve a desired systolic and diastolic pressure at a particular vessel. This 1-D/3-D framework can be used to efficiently determine material and boundary condition parameters for 3-D subject-specific arterial models with deformable vessel walls. Finally, we explore the impact of different anatomical features and hemodynamic conditions on the numerical predictions. The results show good agreement between the two schemes, especially during the diastolic phase of the cycle. PMID:24115509
Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks
NASA Technical Reports Server (NTRS)
Lopez, Alfredo; Grayson, Gary D.; Chandler, Frank O.; Hastings, Leon J.; Heyadat, Ali
2007-01-01
A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in normal gravity. Pressure control is provided by an axial jet thermodynamic vent system (TVS) centered within the vessel that injects cooler liquid into the tank, mixing the contents and reducing tank pressure. The two-phase cryogenic tank model considers liquid hydrogen in its own vapor with liquid density varying with temperature only and a fully compressible ullage. The axisymmetric model is developed using a custom version of the commercially available FLOW-31) software. Quantitative model validation is ,provided by engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage_ Technology Demonstrator (STUSTD) program. The engineering checkout tests provide cryogenic tank self-pressurization test data at various heat leaks and tank fill levels. The predicted self-pressurization rates, ullage and liquid temperatures at discrete locations within the STUSTD tank are in good agreement with test data. The work presented here advances current CFD modeling capabilities for cryogenic pressure control and helps develop a low cost CFD-based design process for space hardware.
Emergent 1d Ising Behavior in AN Elementary Cellular Automaton Model
NASA Astrophysics Data System (ADS)
Kassebaum, Paul G.; Iannacchione, Germano S.
The fundamental nature of an evolving one-dimensional (1D) Ising model is investigated with an elementary cellular automaton (CA) simulation. The emergent CA simulation employs an ensemble of cells in one spatial dimension, each cell capable of two microstates interacting with simple nearest-neighbor rules and incorporating an external field. The behavior of the CA model provides insight into the dynamics of coupled two-state systems not expressible by exact analytical solutions. For instance, state progression graphs show the causal dynamics of a system through time in relation to the system's entropy. Unique graphical analysis techniques are introduced through difference patterns, diffusion patterns, and state progression graphs of the 1D ensemble visualizing the evolution. All analyses are consistent with the known behavior of the 1D Ising system. The CA simulation and new pattern recognition techniques are scalable (in both dimension, complexity, and size) and have many potential applications such as complex design of materials, control of agent systems, and evolutionary mechanism design.
Structural Continuum Modeling of Space Shuttle External Tank Foam Insulation
NASA Technical Reports Server (NTRS)
Steeve, Brian; Ayala, Sam; Purlee, T. Eric; Shaw, Phillip
2006-01-01
The Space Shuttle External Tank is covered with rigid polymeric closed-cell foam insulation to prevent ice formation, protect the metallic tank from aerodynamic heating, and control the breakup of the tank during re-entry. The cryogenic state of the tank, as well as the ascent into a vacuum environment, places this foam under significant stress. Because the loss of the foam during ascent poses a critical risk to the shuttle orbiter, there is much interest in understanding the stress state in the foam insulation and how it may contribute to fracture and debris loss. Several foam applications on the external tank have been analyzed using finite element methods. This presentation describes the approach used to model the foam material behavior and compares analytical results to experiments.
Verification and comparison of four numerical schemes for a 1D viscoelastic blood flow model.
Wang, Xiaofei; Fullana, Jose-Maria; Lagrée, Pierre-Yves
2015-01-01
A reliable and fast numerical scheme is crucial for the 1D simulation of blood flow in compliant vessels. In this paper, a 1D blood flow model is incorporated with a Kelvin-Voigt viscoelastic arterial wall. This leads to a nonlinear hyperbolic-parabolic system, which is then solved with four numerical schemes, namely: MacCormack, Taylor-Galerkin, monotonic upwind scheme for conservation law and local discontinuous Galerkin. The numerical schemes are tested on a single vessel, a simple bifurcation and a network with 55 arteries. The numerical solutions are checked favorably against analytical, semi-analytical solutions or clinical observations. Among the numerical schemes, comparisons are made in four important aspects: accuracy, ability to capture shock-like phenomena, computational speed and implementation complexity. The suitable conditions for the application of each scheme are discussed.
Nested 1D-2D approach for urban surface flood modeling
NASA Astrophysics Data System (ADS)
Murla, Damian; Willems, Patrick
2015-04-01
Floods in urban areas as a consequence of sewer capacity exceedance receive increased attention because of trends in urbanization (increased population density and impermeability of the surface) and climate change. Despite the strong recent developments in numerical modeling of water systems, urban surface flood modeling is still a major challenge. Whereas very advanced and accurate flood modeling systems are in place and operation by many river authorities in support of flood management along rivers, this is not yet the case in urban water management. Reasons include the small scale of the urban inundation processes, the need to have very high resolution topographical information available, and the huge computational demands. Urban drainage related inundation modeling requires a 1D full hydrodynamic model of the sewer network to be coupled with a 2D surface flood model. To reduce the computational times, 0D (flood cones), 1D/quasi-2D surface flood modeling approaches have been developed and applied in some case studies. In this research, a nested 1D/2D hydraulic model has been developed for an urban catchment at the city of Gent (Belgium), linking the underground sewer (minor system) with the overland surface (major system). For the overland surface flood modelling, comparison was made of 0D, 1D/quasi-2D and full 2D approaches. The approaches are advanced by considering nested 1D-2D approaches, including infiltration in the green city areas, and allowing the effects of surface storm water storage to be simulated. An optimal nested combination of three different mesh resolutions was identified; based on a compromise between precision and simulation time for further real-time flood forecasting, warning and control applications. Main streets as mesh zones together with buildings as void regions constitute one of these mesh resolution (3.75m2 - 15m2); they have been included since they channel most of the flood water from the manholes and they improve the accuracy of
Optimisation of A 1d-ecosystem Model To Observations In The North Atlantic Ocean
NASA Astrophysics Data System (ADS)
Schartau, M.; Oschlies, A.
An optimisation experiment is performed with a vertically resolved, nitrogen based ecosystem model, comprising four state variables (1D-NPZD model): dissolved inor- ganic nitrogen (N), phytoplankton (P), herbivorous zooplankton (Z) and detritus (D). Parameter values of the NPZD-model are optimised while regarding observational data from three locations in the North Atlantic simultaneously: Bermuda Atlantic Time-series Study (BATS), data of the North Atlantic Bloom Experiment (NABE) and observations from Ocean Weather Ship-India (OWS-INDIA). The simultaneous opti- misation yields a best parameter set which can be utilized for basin wide simulations in coupled physical-biological (general circulation) models of the North Atlantic. After optimisation of the 1D-NPZD model, systematic discrepancies between 14C-fixation rates and modelled primary production are emphasized. Using the optimal parame- ter estimates for coupled 3D-simulations, the biogeochemical fluxes show substantial differences in contrast to previous model results. For instance, rapid recycling of or- ganic matter enhances primary production rates. This becomes most evident within the oligotrophic regions of the subtropical gyre.
Evaluation of 2 1-D cloud models for the analysis of VAS soundings
NASA Technical Reports Server (NTRS)
Emmitt, G. D.
1984-01-01
Evaluation of the satellite Visual Infrared Spin Scan Radiometer Atmospheric Sounder (VISSR) has begun to document several of its critical shortcomings as far as numerical cloud models are concerned: excessive smoothing of thermal inversions; imprecise measurement of boundary layer moisture; and tendency to exaggerate atmospheric stability. The sensitivity of 1-D cloud models to their required inputs is stressed with special attention to those parameters obtained from atmospheric soundings taken by the VAS or rawinsonde. In addition to performing model experiments using temperature and moisture profiles having the general characteristics of VAS soundings, standard input sensitivity tests were made and 1-D model performance was compared with observations and the results of a 2-D model experiment using AVE/VAS data (Atmospheric Variability Experiment). Although very encouraging, the results are not sufficient to make any specific conclusions. In general, the VAS soundings are likely to be inadequate to provide the cloud base (and subcloud layer) information needed for inputs to current cumulus models. Above cloud base, the tendency to exaggerate the stability of the atmosphere requires solution before meaningful model experiments are run.
Testing a 1-D Analytical Salt Intrusion Model and the Predictive Equation in Malaysian Estuaries
NASA Astrophysics Data System (ADS)
Gisen, Jacqueline Isabella; Savenije, Hubert H. G.
2013-04-01
Little is known about the salt intrusion behaviour in Malaysian estuaries. Study on this topic sometimes requires large amounts of data especially if a 2-D or 3-D numerical models are used for analysis. In poor data environments, 1-D analytical models are more appropriate. For this reason, a fully analytical 1-D salt intrusion model, based on the theory of Savenije in 2005, was tested in three Malaysian estuaries (Bernam, Selangor and Muar) because it is simple and requires minimal data. In order to achieve that, site surveys were conducted in these estuaries during the dry season (June-August) at spring tide by moving boat technique. Data of cross-sections, water levels and salinity were collected, and then analysed with the salt intrusion model. This paper demonstrates a good fit between the simulated and observed salinity distribution for all three estuaries. Additionally, the calibrated Van der Burgh's coefficient K, Dispersion coefficient D0, and salt intrusion length L, for the estuaries also displayed a reasonable correlations with those calculated from the predictive equations. This indicates that not only is the salt intrusion model valid for the case studies in Malaysia but also the predictive model. Furthermore, the results from this study describe the current state of the estuaries with which the Malaysian water authority in Malaysia can make decisions on limiting water abstraction or dredging. Keywords: salt intrusion, Malaysian estuaries, discharge, predictive model, dispersion
6. VIEW OF BRINING TANK Older, redwood model. Paddles agitated ...
6. VIEW OF BRINING TANK Older, redwood model. Paddles agitated the skins while they soaked in brine. The skins were then hung to dry. - Sealing Plant, St. George Island, Pribilof Islands, Saint George, Aleutians West Census Area, AK
7. VIEW OF BRINING TANK Newer, concrete model. After drying, ...
7. VIEW OF BRINING TANK Newer, concrete model. After drying, skins were rolled in borax and packed into barrels, such as those seen in background. - Sealing Plant, St. George Island, Pribilof Islands, Saint George, Aleutians West Census Area, AK
Mathematical Modelling of Thermal Stratification in a Cryogenic Propellant Tank
NASA Astrophysics Data System (ADS)
Agrawal, Gagan; Joseph, Jeswin; Agarwal, Deepak; Pisharady, J. C.; Kumar, S. Sunil
2017-02-01
Cryogenic tanks used for space applications are filled with sub-cooled cryogenic propellants, whose liquid-vapor interface remains undisturbed for long periods of time prior to launch. During this period, substantial amount of heat leaks into the tank from external sources such as solar and ambient convective fluxes, even though the tank is well insulated. This results in thermal stratification near the liquid vapour interface. A transient, two-phase, thermodynamic model of stratification in a cryogenic tank is developed, considering propellant boundary layer flow due to natural convection close to tank wall. Continuity, momentum, energy and mass transfer equations are solved using finite difference-based formulations of SINDA/FLUINT simulator. The analytical model is validated with test results reported in literature. Subsequently, studies are carried out to investigate the effect of liquid sub-cooling in propellant tank on stratified mass and liquid temperature profile. The study shows that sub-cooling of cryogenic tank leads to significant increase in stratified mass.
1D-3D hybrid modeling-from multi-compartment models to full resolution models in space and time.
Grein, Stephan; Stepniewski, Martin; Reiter, Sebastian; Knodel, Markus M; Queisser, Gillian
2014-01-01
Investigation of cellular and network dynamics in the brain by means of modeling and simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling and simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in their level of detail, in order to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing the spatial aspect of each cell. For single cell or networks with relatively small numbers of neurons, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the full three-dimensional morphology of cells and organelles into three-dimensional, space and time-dependent, simulations. While every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. In this paper we present a hybrid simulation approach, that makes use of reduced 1D-models using e.g., the NEURON simulator-which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed three-dimensional morphology of neurons and organelles. In order to couple 1D- and 3D-simulations, we present a geometry-, membrane potential- and intracellular concentration mapping framework, with which graph- based morphologies, e.g., in the swc- or hoc-format, are mapped to full surface and volume representations of the neuron and computational data from 1D-simulations can be used as boundary conditions for full 3D simulations and vice versa. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to the
Quantum Nucleation of Phase Slips in a 1D Model of a Superfluid
Freire, J.A.; Arovas, D.P.; Levine, H.
1997-12-01
We use a 1D model of a superfluid based on the Gross-Pitaevskii Lagrangian to illustrate a general numerical method designed to find quantum tunneling rates in extended bosonic systems. Specifically, we study flow past an obstacle and directly solve the imaginary time dynamics to find the {open_quotes}bounce{close_quotes} solution connected with the decay of the metastable laminar state via phase slip nucleation. The action for the tunneling configuration goes to zero at the threshold (in superfluid velocity) for classical production of these slips. Applications to other processes are briefly discussed. {copyright} {ital 1997} {ital The American Physical Society}
Simulations of Edge Effect in 1D Spin Crossover Compounds by Atom-Phonon Coupling Model
NASA Astrophysics Data System (ADS)
Linares, J.; Chiruta, D.; Jureschi, C. M.; Alayli, Y.; Turcu, C. O.; Dahoo, P. R.
2016-08-01
We used the atom-phonon coupling model to explain and illustrate the behaviour of a linear nano-chain of molecules. The analysis of the system's behaviour was performed using Free Energy method, and by applying Monte Carlo Metropolis (MCM) method which take into account the phonon contribution. In particular we tested both the MCM algorithm and the dynamic-matrix method and we expose how the thermal behaviour of a 1D spin crossover system varies as a function of different factors. Furthermore we blocked the edge atoms of the chain in its high spin state to study the effect on the system's behaviour.
Optimal modeling of 1D azimuth correlations in the context of Bayesian inference
NASA Astrophysics Data System (ADS)
De Kock, Michiel B.; Eggers, Hans C.; Trainor, Thomas A.
2015-09-01
Analysis and interpretation of spectrum and correlation data from high-energy nuclear collisions is currently controversial because two opposing physics narratives derive contradictory implications from the same data, one narrative claiming collision dynamics is dominated by dijet production and projectile-nucleon fragmentation, the other claiming collision dynamics is dominated by a dense, flowing QCD medium. Opposing interpretations seem to be supported by alternative data models, and current model-comparison schemes are unable to distinguish between them. There is clearly need for a convincing new methodology to break the deadlock. In this study we introduce Bayesian inference (BI) methods applied to angular correlation data as a basis to evaluate competing data models. For simplicity the data considered are projections of two-dimensional (2D) angular correlations onto a 1D azimuth from three centrality classes of 200-GeV Au-Au collisions. We consider several data models typical of current model choices, including Fourier series (FS) and a Gaussian plus various combinations of individual cosine components. We evaluate model performance with BI methods and with power-spectrum analysis. We find that FS-only models are rejected in all cases by Bayesian analysis, which always prefers a Gaussian. A cylindrical quadrupole cos(2 ϕ ) is required in some cases but rejected for 0%-5%-central Au-Au collisions. Given a Gaussian centered at the azimuth origin, "higher harmonics" cos(m ϕ ) for m >2 are rejected. A model consisting of Gaussian +dipole cos(ϕ )+quadrupole cos(2 ϕ ) provides good 1D data descriptions in all cases.
Li, Jing; Wang, Min-Yan; Zhang, Jian; He, Wan-Qing; Nie, Lei; Shao, Xia
2013-12-01
VOCs emission from petrochemical storage tanks is one of the important emission sources in the petrochemical industry. In order to find out the VOCs emission amount of petrochemical storage tanks, Tanks 4.0.9d model is utilized to calculate the VOCs emission from different kinds of storage tanks. VOCs emissions from a horizontal tank, a vertical fixed roof tank, an internal floating roof tank and an external floating roof tank were calculated as an example. The consideration of the site meteorological information, the sealing information, the tank content information and unit conversion by using Tanks 4.0.9d model in China was also discussed. Tanks 4.0.9d model can be used to estimate VOCs emissions from petrochemical storage tanks in China as a simple and highly accurate method.
Survey of Multi-Material Closure Models in 1D Lagrangian Hydrodynamics
Maeng, Jungyeoul Brad; Hyde, David Andrew Bulloch
2015-07-28
Accurately treating the coupled sub-cell thermodynamics of computational cells containing multiple materials is an inevitable problem in hydrodynamics simulations, whether due to initial configurations or evolutions of the materials and computational mesh. When solving the hydrodynamics equations within a multi-material cell, we make the assumption of a single velocity field for the entire computational domain, which necessitates the addition of a closure model to attempt to resolve the behavior of the multi-material cells’ constituents. In conjunction with a 1D Lagrangian hydrodynamics code, we present a variety of both the popular as well as more recently proposed multi-material closure models and survey their performances across a spectrum of examples. We consider standard verification tests as well as practical examples using combinations of fluid, solid, and composite constituents within multi-material mixtures. Our survey provides insights into the advantages and disadvantages of various multi-material closure models in different problem configurations.
NASA Astrophysics Data System (ADS)
Shay, Michael; Drake, J.
2005-10-01
We examine a novel simulation scheme called ``equation free projective integration'' which has the potential to allow global simulations which still include microscale physics, a necessary ingredient in order to model multiscale problems. Such codes could be used to examine the global effects of reconnection and turbulence in tokamaks, the Earth's magnetosphere, and the solar corona. Using this method to simulate the propagation and steepening of a 1D ion acoustic wave, we have already achieved excellent agreement between full particle codes and equation free with a factor of 20 speed-up. In this method of simulation, the global plasma variables stepped forward in time are not time-integrated directly using dynamical differential equations, hence the name ``equation free.'' Instead, these variables are represented on a microgrid using a kinetic simulation. This microsimulation is integrated forward long enough to determine the time derivatives of the global plasma variables, which are then used to integrate forward the global variables with much larger timesteps. Results will be presented of the successful application of equation free to 1-D ion acoustic wave steepening with a PIC code serving as the underlying kinetic model. Initial results of this technique applied to magnetic reconnection will also be discussed.
EM modeling of RF drive in DTL tank 4
Kurennoy, Sergey S.
2012-06-19
A 3-D MicroWave Studio model for the RF drive in the LANSCE DTL tank 4 has been built. Both eigensolver and time-domain modeling are used to evaluate maximal fields in the drive module and RF coupling. The LANSCE DTL tank 4 has recently been experiencing RF problems, which may or may not be related to its replaced RF coupler. This situation stimulated a request by Dan Rees to provide EM modeling of the RF drive in the DTL tank 4 (T4). Jim O'Hara provided a CAD model that was imported into the CST Microwave Studio (MWS) and after some modifications became a part of a simplified MWS model of the T4 RF drive. This technical note describes the model and presents simulation results.
Simscape Modeling of a Custom Closed-Volume Tank
NASA Technical Reports Server (NTRS)
Fischer, Nathaniel P.
2015-01-01
The library for Mathworks Simscape does not currently contain a model for a closed volume fluid tank where the ullage pressure is variable. In order to model a closed-volume variable ullage pressure tank, it was necessary to consider at least two separate cases: a vertical cylinder, and a sphere. Using library components, it was possible to construct a rough model for the cylindrical tank. It was not possible to construct a model for a spherical tank, using library components, due to the variable area. It was decided that, for these cases, it would be preferable to create a custom library component to represent each case, using the Simscape language. Once completed, the components were added to models, where filling and draining the tanks could be simulated. When the models were performing as expected, it was necessary to generate code from the models and run them in Trick (a real-time simulation program). The data output from Trick was then compared to the output from Simscape and found to be within acceptable limits.
Model based, sensor-directed remediation of underground storage tanks
Harrigan, R.W.; Thunborg, S. )
1990-06-01
Sensor-rich, intelligent robots that function with respect to models of their environment have significant potential to reduce the time and cost for the cleanup of hazardous waste while increasing operator safety. Sandia National Laboratories (SNL) is performing technology development and experimental investigations into the application of intelligent robot control technology to the problem of cleaning up waste stored in underground tanks. The tasks addressed in the SNL experiments are in situ physical characterizations of underground storage tanks (USTs) as well as the contained waste and the removal of the waste from the tank both for laboratory analysis and as part of the tank cleanup process. Both fully automatic and manual robot control technologies are being developed and demonstrated. The SNL-developed concept of human-assisted computer control will be employed whenever manual control of the robot is required. The UST Robot Technology Development Laboratory (URTDL) consists of a commercial gantry robot modified to allow hybrid force/position control.
1D finite volume model of unsteady flow over mobile bed
NASA Astrophysics Data System (ADS)
Zhang, Shiyan; Duan, Jennifer G.
2011-07-01
SummaryA one dimensional (1D) finite volume method (FVM) model was developed for simulating unsteady flow, such as dam break flow, and flood routing over mobile alluvium. The governing equation is the modified 1D shallow water equation and the Exner equation that take both bed load and suspended load transport into account. The non-equilibrium sediment transport algorithm was adopted in the model, and the van Rijn method was employed to calculate the bed-load transport rate and the concentration of suspended sediment at the reference level. Flux terms in the governing equations were discretised using the upwind flux scheme, Harten et al. (1983) (HLL) and HLLC schemes, Roe's scheme and the Weighted Average Flux (WAF) schemes with the Double Minmod and Minmod flux limiters. The model was tested under a fixed bed condition to evaluate the performance of several different numerical schemes and then applied to an experimental case of dam break flow over a mobile bed and a flood event in the Rillito River, Tucson, Arizona. For dam break flow over movable bed, all tested schemes were proved to be capable of reasonably simulating water surface profiles, but failed to accurately capture the hydraulic jump. The WAF schemes produced slight spurious oscillations at the water surface and bed profiles and over-estimated the scour depth. When applying the model to the Rillito River, the simulated results generally agreed well with the field measurements of flow discharges and bed elevation changes. Modeling results of bed elevation changes were sensitive to the suspended load recovery coefficient and the bed load adaptation length, which require further theoretical and experimental investigations.
This technical report describes the new one-dimensional (1D) hydrodynamic and sediment transport model EFDC1D. This model that can be applied to stream networks. The model code and two sample data sets are included on the distribution CD. EFDC1D can simulate bi-directional unstea...
Stability of Blowup for a 1D Model of Axisymmetric 3D Euler Equation
NASA Astrophysics Data System (ADS)
Do, Tam; Kiselev, Alexander; Xu, Xiaoqian
2016-10-01
The question of the global regularity versus finite- time blowup in solutions of the 3D incompressible Euler equation is a major open problem of modern applied analysis. In this paper, we study a class of one-dimensional models of the axisymmetric hyperbolic boundary blow-up scenario for the 3D Euler equation proposed by Hou and Luo (Multiscale Model Simul 12:1722-1776, 2014) based on extensive numerical simulations. These models generalize the 1D Hou-Luo model suggested in Hou and Luo Luo and Hou (2014), for which finite-time blowup has been established in Choi et al. (arXiv preprint. arXiv:1407.4776, 2014). The main new aspects of this work are twofold. First, we establish finite-time blowup for a model that is a closer approximation of the three-dimensional case than the original Hou-Luo model, in the sense that it contains relevant lower-order terms in the Biot-Savart law that have been discarded in Hou and Luo Choi et al. (2014). Secondly, we show that the blow-up mechanism is quite robust, by considering a broader family of models with the same main term as in the Hou-Luo model. Such blow-up stability result may be useful in further work on understanding the 3D hyperbolic blow-up scenario.
GE SBWR stability analysis using TRAC-BF1 1-D kinetics model
Lu, S.; Baratta, A.J.; Robinson, G.E.
1996-07-01
GE`s simplified boiling water reactor, with its unique feature of using natural circulation to remove the heat from the reactor core, is a complicated dynamic system. Previous work by authors using the TRAC-BF1 code and a point kinetics model predicted that an SBWR may experience large amplitude power oscillation under certain low pressure and high power operating conditions. To further confirm the existence of this power oscillation and explore the dynamic spatial reactor power distribution, the TRAC-BF1 1-D kinetics model was used. The results show that an instability exists and the power oscillation starting time and maximum peak power are different from the point kinetics results.
Fluid friction and wall viscosity of the 1D blood flow model.
Wang, Xiao-Fei; Nishi, Shohei; Matsukawa, Mami; Ghigo, Arthur; Lagrée, Pierre-Yves; Fullana, Jose-Maria
2016-02-29
We study the behavior of the pulse waves of water into a flexible tube for application to blood flow simulations. In pulse waves both fluid friction and wall viscosity are damping factors, and difficult to evaluate separately. In this paper, the coefficients of fluid friction and wall viscosity are estimated by fitting a nonlinear 1D flow model to experimental data. In the experimental setup, a distensible tube is connected to a piston pump at one end and closed at another end. The pressure and wall displacements are measured simultaneously. A good agreement between model predictions and experiments was achieved. For amplitude decrease, the effect of wall viscosity on the pulse wave has been shown as important as that of fluid viscosity.
One-electron singular spectral features of the 1D Hubbard model at finite magnetic field
NASA Astrophysics Data System (ADS)
Carmelo, J. M. P.; Čadež, T.
2017-01-01
The momentum, electronic density, spin density, and interaction dependences of the exponents that control the (k , ω)-plane singular features of the σ = ↑ , ↓ one-electron spectral functions of the 1D Hubbard model at finite magnetic field are studied. The usual half-filling concepts of one-electron lower Hubbard band and upper Hubbard band are defined in terms of the rotated electrons associated with the model Bethe-ansatz solution for all electronic density and spin density values and the whole finite repulsion range. Such rotated electrons are the link of the non-perturbative relation between the electrons and the pseudofermions. Our results further clarify the microscopic processes through which the pseudofermion dynamical theory accounts for the one-electron matrix elements between the ground state and excited energy eigenstates.
Minimum 1-D P-wave velocity reference model for Northern Iran
NASA Astrophysics Data System (ADS)
Rezaeifar, Meysam; Diehl, Tobias; Kissling, Edi
2016-04-01
Uniform high-precision earthquake location is of importance in a seismically active area like northern Iran where the earthquake catalogue is a prerequisite for seismic hazard assessment and tectonic interpretation. We compile a complete and consistent local earthquake data set for the northern Iran region, using information from two independently operating seismological networks, Iran Seismological Center (IRSC) network, administered by the Geophysical Institute of Tehran University, and Iran Broadband network administered by International Institute of Engineering Earthquake and Seismology (IIEES). Special care is taken during the merging process to reduce the number of errors in the data, including station parameters, event pairing, phase identification, and to the assessment of quantitative observation uncertainties. The derived P-wave 1D-velocity model for Northern Iran may serve for consistent routine high-precision earthquake location and as initial reference model for 3D seismic tomography.
NASA Astrophysics Data System (ADS)
Klimeck, Gerhard
2001-03-01
The quantum mechanical functionality of commercially pursued heterostructure devices such as resonant tunneling diodes (RTDs), quantum well infrared photodetectors, and quantum well lasers are enabled by material variations on an atomic scale. The creation of these heterostructure devices is realized in a vast design space of material compositions, layer thicknesses and doping profiles. The full experimental exploration of this design space is unfeasible and a reliable design tool is needed. The Nanoelectronic Modeling tool (NEMO) is one of the first commercial grade attempts for such a modeling tool. NEMO was developed as a general-purpose quantum mechanics-based 1-D device design and analysis tool from 1993-97 by the Central Research Laboratory of Texas Instruments (later Raytheon Systems). NEMO enables(R. Lake, G. Klimeck, R. C. Bowen, and D. Jovanovic, J. Appl. Phys. 81), 7845 (1997). the fundamentally sound inclusion of the required(G. Klimeck et al.), in the 1997 55th Annual Device Research Conference Digest, (IEEE, NJ, 1997), p. 92^,(R. C. Bowen et al.), J. Appl. Phys 81, 3207 (1997). physics: bandstructure, scattering, and charge self-consistency based on the non-equilibrium Green function approach. A new class of devices which require full 3-D quantum mechanics based models is starting to emerge: quantum dots, or in general semiconductor based deca-nano devices. We are currently building a 3-D modeling tool based on NEMO to include the important physics to understand electronic stated in such superscaled structures. This presentation will overview various facets of the NEMO 1-D tool such electron transport physics in RTDs, numerical technology, software engineering and graphical user interface. The lessons learned from that work are now entering the NEMO 3-D development and first results using the NEMO 3-D prototype will be shown. More information about
A world-line framework for 1D topological conformal σ-models
NASA Astrophysics Data System (ADS)
Baulieu, L.; Holanda, N. L.; Toppan, F.
2015-11-01
We use world-line methods for pseudo-supersymmetry to construct sl(2|1)-invariant actions for the (2, 2, 0) chiral and (1, 2, 1) real supermultiplets of the twisted D-module representations of the sl(2|1) superalgebra. The derived one-dimensional topological conformal σ-models are invariant under nilpotent operators. The actions are constructed for both parabolic and hyperbolic/trigonometric realizations (with extra potential terms in the latter case). The scaling dimension λ of the supermultiplets defines a coupling constant, 2λ + 1, the free theories being recovered at λ = - /1 2 . We also present, generalizing previous works, the D-module representations of one-dimensional superconformal algebras induced by N = ( p , q ) pseudo-supersymmetry acting on (k, n, n - k) supermultiplets. Besides sl(2|1), we obtain the superalgebras A(1, 1), D(2, 1; α), D(3, 1), D(4, 1), A(2, 1) from (p, q) = (1, 1), (2, 2), (3, 3), (4, 4), (5, 1), at given k, n and critical values of λ.
Numerical Modeling of Propellant Boiloff in Cryogenic Storage Tank
NASA Technical Reports Server (NTRS)
Majumdar, A. K.; Steadman, T. E.; Maroney, J. L.
2007-01-01
This Technical Memorandum (TM) describes the thermal modeling effort undertaken at Marshall Space Flight Center to support the Cryogenic Test Laboratory at Kennedy Space Center (KSC) for a study of insulation materials for cryogenic tanks in order to reduce propellant boiloff during long-term storage. The Generalized Fluid System Simulation program has been used to model boiloff in 1,000-L demonstration tanks built for testing the thermal performance of glass bubbles and perlite insulation. Numerical predictions of boiloff rate and ullage temperature have been compared with the measured data from the testing of demonstration tanks. A satisfactory comparison between measured and predicted data has been observed for both liquid nitrogen and hydrogen tests. Based on the experience gained with the modeling of the demonstration tanks, a numerical model of the liquid hydrogen storage tank at launch complex 39 at KSC was built. The predicted boiloff rate of hydrogen has been found to be in good agreement with observed field data. This TM describes three different models that have been developed during this period of study (March 2005 to June 2006), comparisons with test data, and results of parametric studies.
Full Waveform 3D Synthetic Seismic Algorithm for 1D Layered Anelastic Models
NASA Astrophysics Data System (ADS)
Schwaiger, H. F.; Aldridge, D. F.; Haney, M. M.
2007-12-01
Numerical calculation of synthetic seismograms for 1D layered earth models remains a significant aspect of amplitude-offset investigations, surface wave studies, microseismic event location approaches, and reflection interpretation or inversion processes. Compared to 3D finite-difference algorithms, memory demand and execution time are greatly reduced, enabling rapid generation of seismic data within workstation or laptop computational environments. We have developed a frequency-wavenumber forward modeling algorithm adapted to realistic 1D geologic media, for the purpose of calculating seismograms accurately and efficiently. The earth model consists of N layers bounded by two halfspaces. Each layer/halfspace is a homogeneous and isotropic anelastic (attenuative and dispersive) solid, characterized by a rectangular relaxation spectrum of absorption mechanisms. Compressional and shear phase speeds and quality factors are specified at a particular reference frequency. Solution methodology involves 3D Fourier transforming the three coupled, second- order, integro-differential equations for particle displacements to the frequency-horizontal wavenumber domain. An analytic solution of the resulting ordinary differential system is obtained. Imposition of welded interface conditions (continuity of displacement and stress) at all interfaces, as well as radiation conditions in the two halfspaces, yields a system of 6(N+1) linear algebraic equations for the coefficients in the ODE solution. An optimized inverse 2D Fourier transform to the space domain gives the seismic wavefield on a horizontal plane. Finally, three-component seismograms are obtained by accumulating frequency spectra at designated receiver positions on this plane, followed by a 1D inverse FFT from angular frequency ω to time. Stress-free conditions may be applied at the top or bottom interfaces, and seismic waves are initiated by force or moment density sources. Examples reveal that including attenuation
Numerical modeling of the flow in a cryogenic fuel tank
NASA Astrophysics Data System (ADS)
Greer, Donald Steven
Developing reusable flight weight cryogenic fuel tanks is one of the technological challenges in designing advanced hypersonic aircraft and the next generation of spacecraft. As an aid in the design of these aircraft, a computational fluid dynamics (CFD) model has been developed specifically for the analysis of flow in a cryogenic fuel tank. The model simulates the transient, two dimensional draining of a fuel tank cross section. The interface between the ullage gas and liquid fuel is modeled as a free surface to enable the calculation of slosh wave dynamics. The drain rate of the liquid fuel is specified as a boundary condition to the model. The ullage gas enters the model to replace the volume of drained liquid. The rate of ullage gas entering the model is calculated from boundary conditions of constant pressure and temperature for the ullage gas. The model employs the full set of Navier-Stokes equations with the exception that viscous dissipation is neglected in the energy equation. The method of solution is an explicit finite difference technique in two dimensional generalized coordinates approximated to second order accuracy in both space and time. The stiffness due to the low Mach number is handled by the method of artificial compressibility. Model comparisons are made to experimental data for free convection to a vertical plate and to free convection inside a horizontal cylinder. Slosh wave dynamics are compared to potential flow calculations for waves inside a square tank. Sample calculations are also performed on a rectangular tank and an eight sided polygon tank to demonstrate the capability of the model.
1D numerical model of muddy subaqueous and subaerial debris flows
Imran, J.; Parker, G.; Locat, J.; Lee, H.
2001-01-01
A 1D numerical model of the downslope flow and deposition of muddy subaerial and subaqueous debris flows is presented. The model incorporates the Herschel-Bulkley and bilinear rheologies of viscoplastic fluid. The more familiar Bingham model is integrated into the Herschel-Bulkley rheological model. The conservation equations of mass and momentum of single-phase laminar debris flow are layer-integrated using the slender flow approximation. They are then expressed in a Lagrangian framework and solved numerically using an explicit finite difference scheme. Starting from a given initial shape, a debris flow is allowed to collapse and propagate over a specified topography. Comparison between the model predictions and laboratory experiments shows reasonable agreement. The model is used to study the effect of the ambient fluid density, initial shape of the failed mass, and rheological model on the simulated propagation of the front and runout characteristics of muddy debris flows. It is found that initial failure shape influence the front velocity but has little bearing on the final deposit shape. In the Bingham model, the excess of shear stress above the yield strength is proportional to the strain rate to the first power. This exponent is free to vary in the Herschel-Bulkley model. When it is set at a value lower than unity, the resulting final deposits are thicker and shorter than in the case of the Bingham rheology. The final deposit resulting from the bilinear model is longer and thinner than that from the Bingham model due to the fact that the debris flow is allowed to act as a Newtonian fluid at low shear rate in the bilinear model.
Thermodynamic Modeling of Hanford Waste Tank 241-AN-107
Felmy, Andrew R.
2005-09-07
The high level waste storage double-shell tanks at the Hanford site are highly basic. The high basicity is a key factor in controlling the chemical behavior of different components of the waste and in influencing the corrosion rate of the carbon steel primary tanks. However, the introduction of atmospheric CO2 can act to reduce the pH of the tank wastes over time and possibly alter the corrosion rate of the carbon steel tanks. In order to at least partially address this issue for waste tank 241-AN-107, thermodynamic modeling calculations were performed to predict the changes in pH and carbonate concentration that could occur as CO2 is absorbed from the atmosphere. The calculations extended to complete equilibrium with the partial pressure of CO2 in the atmosphere (i.e. pCO2 = 10-3.5 atm). Simulations were performed for both the “upper” segments of tank 241-AN-107, which have been influenced by the introduction of high concentrations of NaOH to the supernatant, and for the “lower” segments where the salt cake/interstitial liquid have not been substantially altered by the introduction of base concentration.
2D Biotope Mapping Using Combined LIDAR, Topographic Survey And Segmented 1D Flow Modelling
NASA Astrophysics Data System (ADS)
Entwistle, N. S.; Heritage, G. L.; Milan, D. J.
2009-12-01
Reach averaged habitat availability models such as PHABSIM are limited due principally to their failure to adequately map hydraulic habitat distribution at a representative scale. A lack of morphologic data, represented in the form of sparse geometric cross-sections fails to generate the necessary detail. Advances in data collection, improved spatial modelling algorithms and the advent of cross-section based segmentation routines in 1D hydraulic models provides the opportunity to revisit the issue of hydraulic habitat mapping and modelling. This paper presents a combined technique for habitat characterisation at the sub-bar scale is presented for the River Rede, Northumberland, UK. Terrestrial LIDAR data of floodplain, banks and exposed bar surfaces at an average 0.05 m spacing are combined with sparser total station survey data of submerged morphologic features. These data are interpolated to create a uniform DEM grid at 0.2 m spacing (adequate to detect the smallest variation in hydraulic habitat in this system). The data grid were then imported into the HECRAS 1D hydraulic model to generate a 2 m spaced series of cross-sections along a 220 m sinuous single thread reach exhibiting pool - riffle point-bar morphology. The hydraulic segmentation routine then generated estimates of depth averaged flow velocity, flow depth and sub unit discharge for 40 sub-divisions of the flow width for a series of flows from 0.5 m3s-1 up to bankfull flow of approximately 9 m3s-1. The resultant hydraulic data were exported in the project coordinate system and plotted to reveal the 2D pattern of hydraulic biotopes present across the range of flows modelled. The results reveal broadly realistic patterns consistent with previous empirical studies and compare well with LIDAR based biotope maps. Analysis of the temporal pattern of biotope change indicates that biotope diversity and complexity is at a maximum at lower flows and across shallower area (riffles) and that these dominate the
Initial Stage of the Microwave Ionization Wave Within a 1D Model
NASA Astrophysics Data System (ADS)
Semenov, V. E.; Rakova, E. I.; Glyavin, M. Yu.; Nusinovich, G. S.
2016-05-01
The dynamics of the microwave breakdown in a gas is simulated numerically within a simple 1D model which takes into account such processes as the impact ionization of gas molecules, the attachment of electrons to neutral molecules, and plasma diffusion. Calculations are carried out for different spatial distributions of seed electrons with account for reflection of the incident electromagnetic wave from the plasma. The results reveal considerable dependence of the ionization wave evolution on the relation between the field frequency and gas pressure, as well as on the existence of extended rarefied halo of seed electrons. At relatively low gas pressures (or high field frequencies), the breakdown process is accompanied by the stationary ionization wave moving towards the incident electromagnetic wave. In the case of a high gas pressure (or a relatively low field frequency), the peculiarities of the breakdown are associated with the formation of repetitive jumps of the ionization front.
NASA Astrophysics Data System (ADS)
Baghdasaryan, Hovik V.; Knyazyan, Tamara M.
2003-12-01
The principles of the method of single expression (MSE) for boundary problems solution in classical electrodynamics are presented. In the MSE the solution of the Helmholtz's equation is presented in the special form of a single expression describing resultant amplitude and phase distributions in the medium. This form of solution presenation permits to pass over the restrictions of the superposition principle and to solve both linear and nonlinear problems with ths same ease. In the MSE the Helmholtz's equation is reformulated to the set of first order differential equations and the boundary problem is solved numerically. No approximations are implied either in Helmholtz's equation or in boundary conditions. Using the MSE steady-state boundary problems are modeled for wavelength scale multilayer and modulated 1D photonic structures including amplification and nonuniformity evoked by intense electromagnetic field.
NASA Astrophysics Data System (ADS)
Shay, M. A.; Dorland, B.; Drake, J. F.; Stantchev, G.
2005-12-01
We examine a novel simulation scheme called "equation free projective integration"[1] which has the potential to allow global simulations which still include microscale physics, a necessary ingredient in order to model multiscale problems. Such codes could be used to examine the global effects of reconnection and turbulence in the Earth's magnetosphere, and the solar corona, as well as in laboratory Tokamaks. Using this method to simulate the propagation and steepening of a 1D ion acoustic wave, we have already achieved excellent agreement between full particle codes and equation free with a factor of 20 speed-up. This speedup appears to scale linearly with system size, so large scale 2D and 3D simulations using this method will show a speedup of 100 or more. In this method of simulation, the global plasma variables stepped forward in time are not time-integrated directly using dynamical differential equations, hence the name "equation free." Instead, these variables are represented on a microgrid using a kinetic simulation. This microsimulation is integrated forward long enough to determine the time derivatives of the global plasma variables, which are then used to integrate forward the global variables with much larger timesteps. Results will be presented of the successful application of equation free to 1-D ion acoustic wave steepening with a PIC code serving as the underlying kinetic model. Initial results of this technique applied to magnetic reconnection will also be discussed. 1 I. G. Kevrekidis et. al., Equation-free multiscale computation: Enabling microscopic simulators to perform system-level tasks, arXiv:physics/0209043.
Kinetic study of run-away burn in ICF capsule using a quasi-1D model
NASA Astrophysics Data System (ADS)
Huang, Chengkun; Molvig, K.; Albright, B. J.; Dodd, E. S.; Hoffman, N. M.; Vold, E. L.; Kagan, G.
2016-10-01
The effect of reduced fusion reactivity resulting from the loss of fuel ions in the Gamow peak in the ignition, run-away burn and disassembly stages of an inertial confinement fusion D-T capsule is investigated with a quasi-1D hybrid model that includes kinetic ions, fluid electrons and Planckian radiation photons. The fuel ion loss through the Knudsen effect at the fuel-pusher interface is accounted for by a local-loss model developed in Molvig et al.. The tail refilling and relaxation of the fuel ion distribution are evolved with a nonlinear Fokker-Planck solver. The Krokhin & Rozanov model is used for the finite alpha range beyond the fuel region, while alpha heating to the fuel ions and the fluid electrons is modeled kinetically. For an energetic pusher (40kJ), the simulation shows that the reduced fusion reactivity can lead to substantially lower ion temperature during run-away burn, while the final yield decreases more modestly. Possible improvements to the present model, including the non-Planckian radiation emission and alpha-driven fuel disassembly, are discussed. Work performed under the auspices of the U.S. DOE by the LANS, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396. Work supported by the ASC TBI project at LANL.
HELIOS-CR A 1-D radiation-magnetohydrodynamics code with inline atomic kinetics modeling
NASA Astrophysics Data System (ADS)
Macfarlane, J. J.; Golovkin, I. E.; Woodruff, P. R.
2006-05-01
HELIOS-CR is a user-oriented 1D radiation-magnetohydrodynamics code to simulate the dynamic evolution of laser-produced plasmas and z-pinch plasmas. It includes an in-line collisional-radiative (CR) model for computing non-LTE atomic level populations at each time step of the hydrodynamics simulation. HELIOS-CR has been designed for ease of use, and is well-suited for experimentalists, as well as graduate and undergraduate student researchers. The energy equations employed include models for laser energy deposition, radiation from external sources, and high-current discharges. Radiative transport can be calculated using either a multi-frequency flux-limited diffusion model, or a multi-frequency, multi-angle short characteristics model. HELIOS-CR supports the use of SESAME equation of state (EOS) tables, PROPACEOS EOS/multi-group opacity data tables, and non-LTE plasma properties computed using the inline CR modeling. Time-, space-, and frequency-dependent results from HELIOS-CR calculations are readily displayed with the HydroPLOT graphics tool. In addition, the results of HELIOS simulations can be post-processed using the SPECT3D Imaging and Spectral Analysis Suite to generate images and spectra that can be directly compared with experimental measurements. The HELIOS-CR package runs on Windows, Linux, and Mac OSX platforms, and includes online documentation. We will discuss the major features of HELIOS-CR, and present example results from simulations.
Thermodynamic models for bounding pressurant mass requirements of cryogenic tanks
NASA Technical Reports Server (NTRS)
Vandresar, Neil T.; Haberbusch, Mark S.
1994-01-01
Thermodynamic models have been formulated to predict lower and upper bounds for the mass of pressurant gas required to pressurize a cryogenic tank and then expel liquid from the tank. Limiting conditions are based on either thermal equilibrium or zero energy exchange between the pressurant gas and initial tank contents. The models are independent of gravity level and allow specification of autogenous or non-condensible pressurants. Partial liquid fill levels may be specified for initial and final conditions. Model predictions are shown to successfully bound results from limited normal-gravity tests with condensable and non-condensable pressurant gases. Representative maximum collapse factor maps are presented for liquid hydrogen to show the effects of initial and final fill level on the range of pressurant gas requirements. Maximum collapse factors occur for partial expulsions with large final liquid fill fractions.
Structural Continuum Modeling of Space Shuttle External Tank Foam Insulation
NASA Technical Reports Server (NTRS)
Steeve, Brian; Ayala, Sam; Purlee, T. Eric; Shaw, Phillip
2006-01-01
This document is a viewgraph presentation reporting on work in modeling the foam insulation of the Space Shuttle External Tank. An analytical understanding of foam mechanics is required to design against structural failure. The Space Shuttle External Tank is covered primarily with closed cell foam to: Prevent ice, Protect structure from ascent aerodynamic and engine plume heating, and Delay break-up during re-entry. It is important that the foam does not shed unacceptable debris during ascent environment. Therefore a modeling of the foam insulation was undertaken.
Numerical modeling of a cryogenic fluid within a fuel tank
NASA Technical Reports Server (NTRS)
Greer, Donald S.
1994-01-01
The computational method developed to study the cryogenic fluid characteristics inside a fuel tank in a hypersonic aircraft is presented. The model simulates a rapid draining of the tank by modeling the ullage vapor and the cryogenic liquid with a moving interface. A mathematical transformation was developed and applied to the Navier-Stokes equations to account for the moving interface. The formulation of the numerical method is a transient hybrid explicit-implicit technique where the pressure term in the momentum equations is approximated to first order in time by combining the continuity equation with an ideal equation of state.
Testing the accuracy of a 1-D volcanic plume model in estimating mass eruption rate
Mastin, Larry G.
2014-01-01
During volcanic eruptions, empirical relationships are used to estimate mass eruption rate from plume height. Although simple, such relationships can be inaccurate and can underestimate rates in windy conditions. One-dimensional plume models can incorporate atmospheric conditions and give potentially more accurate estimates. Here I present a 1-D model for plumes in crosswind and simulate 25 historical eruptions where plume height Hobs was well observed and mass eruption rate Mobs could be calculated from mapped deposit mass and observed duration. The simulations considered wind, temperature, and phase changes of water. Atmospheric conditions were obtained from the National Center for Atmospheric Research Reanalysis 2.5° model. Simulations calculate the minimum, maximum, and average values (Mmin, Mmax, and Mavg) that fit the plume height. Eruption rates were also estimated from the empirical formula Mempir = 140Hobs4.14 (Mempir is in kilogram per second, Hobs is in kilometer). For these eruptions, the standard error of the residual in log space is about 0.53 for Mavg and 0.50 for Mempir. Thus, for this data set, the model is slightly less accurate at predicting Mobs than the empirical curve. The inability of this model to improve eruption rate estimates may lie in the limited accuracy of even well-observed plume heights, inaccurate model formulation, or the fact that most eruptions examined were not highly influenced by wind. For the low, wind-blown plume of 14–18 April 2010 at Eyjafjallajökull, where an accurate plume height time series is available, modeled rates do agree better with Mobs than Mempir.
Assessing the habitability of planets with Earth-like atmospheres with 1D and 3D climate modeling
NASA Astrophysics Data System (ADS)
Godolt, M.; Grenfell, J. L.; Kitzmann, D.; Kunze, M.; Langematz, U.; Patzer, A. B. C.; Rauer, H.; Stracke, B.
2016-07-01
Context. The habitable zone (HZ) describes the range of orbital distances around a star where the existence of liquid water on the surface of an Earth-like planet is in principle possible. The applicability of one-dimensional (1D) climate models for the estimation of the HZ boundaries has been questioned by recent three-dimensional (3D) climate studies. While 3D studies can calculate the water vapor, ice albedo, and cloud feedback self-consistently and therefore allow for a deeper understanding and the identification of relevant climate processes, 1D model studies rely on fewer model assumptions and can be more easily applied to the large parameter space possible for extrasolar planets. Aims: We evaluate the applicability of 1D climate models to estimate the potential habitability of Earth-like extrasolar planets by comparing our 1D model results to those of 3D climate studies in the literature. We vary the two important planetary properties, surface albedo and relative humidity, in the 1D model. These depend on climate feedbacks that are not treated self-consistently in most 1D models. Methods: We applied a cloud-free 1D radiative-convective climate model to calculate the climate of Earth-like planets around different types of main-sequence stars with varying surface albedo and relative humidity profile. We compared the results to those of 3D model calculations available in the literature and investigated to what extent the 1D model can approximate the surface temperatures calculated by the 3D models. Results: The 1D parameter study results in a large range of climates possible for an Earth-sized planet with an Earth-like atmosphere and water reservoir at a certain stellar insolation. At some stellar insolations the full spectrum of climate states could be realized, i.e., uninhabitable conditions due to surface temperatures that are too high or too low as well as habitable surface conditions, depending only on the relative humidity and surface albedo assumed. When
Cryogenic Tank Modeling for the Saturn AS-203 Experiment
NASA Technical Reports Server (NTRS)
Grayson, Gary D.; Lopez, Alfredo; Chandler, Frank O.; Hastings, Leon J.; Tucker, Stephen P.
2006-01-01
A computational fluid dynamics (CFD) model is developed for the Saturn S-IVB liquid hydrogen (LH2) tank to simulate the 1966 AS-203 flight experiment. This significant experiment is the only known, adequately-instrumented, low-gravity, cryogenic self pressurization test that is well suited for CFD model validation. A 4000-cell, axisymmetric model predicts motion of the LH2 surface including boil-off and thermal stratification in the liquid and gas phases. The model is based on a modified version of the commercially available FLOW3D software. During the experiment, heat enters the LH2 tank through the tank forward dome, side wall, aft dome, and common bulkhead. In both model and test the liquid and gases thermally stratify in the low-gravity natural convection environment. LH2 boils at the free surface which in turn increases the pressure within the tank during the 5360 second experiment. The Saturn S-IVB tank model is shown to accurately simulate the self pressurization and thermal stratification in the 1966 AS-203 test. The average predicted pressurization rate is within 4% of the pressure rise rate suggested by test data. Ullage temperature results are also in good agreement with the test where the model predicts an ullage temperature rise rate within 6% of the measured data. The model is based on first principles only and includes no adjustments to bring the predictions closer to the test data. Although quantitative model validation is achieved or one specific case, a significant step is taken towards demonstrating general use of CFD for low-gravity cryogenic fluid modeling.
A 1-D evolutionary model for icy satellites, applied to Enceladus
NASA Astrophysics Data System (ADS)
Malamud, Uri; Prialnik, Dina
2016-04-01
We develop a long-term 1-D evolution model for icy satellites that couples multiple processes: water migration and differentiation, geochemical reactions and silicate phase transitions, compaction by self-gravity, and ablation. The model further considers the following energy sources and sinks: tidal heating, radiogenic heating, geochemical energy released by serpentinization or absorbed by mineral dehydration, gravitational energy and insolation, and heat transport by conduction, convection, and advection. We apply the model to Enceladus, by guessing the initial conditions that would render a structure compatible with present-day observations, assuming the initial structure to have been homogeneous. Assuming the satellite has been losing water continually along its evolution, we postulate that it was formed as a more massive, more icy and more porous satellite, and gradually transformed into its present day state due to sustained long-term tidal heating. We consider several initial compositions and evolution scenarios and follow the evolution for the age of the Solar System, testing the present day model results against the available observational constraints. Our model shows the present configuration to be differentiated into a pure icy mantle, several tens of km thick, overlying a rocky core, composed of dehydrated rock at the center and hydrated rock in the outer part. For Enceladus, it predicts a higher rock/ice mass ratio than previously assumed and a thinner ice mantle, compatible with recent estimates based on gravity field measurements. Although, obviously, the model cannot be used to explain local phenomena, it sheds light on the internal structure invoked in explanations of localized features and activities.
NASA Astrophysics Data System (ADS)
Hassan, Kazi; Allen, Deonie; Haynes, Heather
2016-04-01
This paper considers 1D hydraulic model data on the effect of high flow clusters and sequencing on sediment transport. Using observed flow gauge data from the River Caldew, England, a novel stochastic modelling approach was developed in order to create alternative 50 year flow sequences. Whilst the observed probability density of gauge data was preserved in all sequences, the order in which those flows occurred was varied using the output from a Hidden Markov Model (HMM) with generalised Pareto distribution (GP). In total, one hundred 50 year synthetic flow series were generated and used as the inflow boundary conditions for individual flow series model runs using the 1D sediment transport model HEC-RAS. The model routed graded sediment through the case study river reach to define the long-term morphological changes. Comparison of individual simulations provided a detailed understanding of the sensitivity of channel capacity to flow sequence. Specifically, each 50 year synthetic flow sequence was analysed using a 3-month, 6-month or 12-month rolling window approach and classified for clusters in peak discharge. As a cluster is described as a temporal grouping of flow events above a specified threshold, the threshold condition used herein is considered as a morphologically active channel forming discharge event. Thus, clusters were identified for peak discharges in excess of 10%, 20%, 50%, 100% and 150% of the 1 year Return Period (RP) event. The window of above-peak flows also required cluster definition and was tested for timeframes 1, 2, 10 and 30 days. Subsequently, clusters could be described in terms of the number of events, maximum peak flow discharge, cumulative flow discharge and skewness (i.e. a description of the flow sequence). The model output for each cluster was analysed for the cumulative flow volume and cumulative sediment transport (mass). This was then compared to the total sediment transport of a single flow event of equivalent flow volume
1D-coupled photochemical model of neutrals, cations and anions in the atmosphere of Titan
NASA Astrophysics Data System (ADS)
Dobrijevic, M.; Loison, J. C.; Hickson, K. M.; Gronoff, G.
2016-04-01
Many models with different characteristics have been published so far to study the chemical processes at work in Titan's atmosphere. Some models focus on neutral species in the stratosphere or ionic species in the ionosphere, but few of them couple all the species throughout the whole atmosphere. Very few of these emphasize the importance of uncertainties in the chemical scheme and study their propagation in the model. We have developed a new 1D-photochemical model of Titan's atmosphere coupling neutral species with positive and negative ions from the lower atmosphere up to the ionosphere and have compared our results with observations to have a comprehensive view of the chemical processes driving the composition of the stratosphere and ionosphere of Titan. We have updated the neutral, positive ion and negative ion chemistry and have improved the description of N2 photodissociation by introducing high resolution N2 absorption cross sections. We performed for the first time an uncertainty propagation study in a fully coupled ion-neutral model. We determine how uncertainties on rate constants on both neutral and ionic reactions influence the model results and pinpoint the key reactions responsible for this behavior. We find very good agreement between our model results and observations in both the stratosphere and in the ionosphere for most neutral compounds. Our results are also in good agreement with an average INMS mass spectrum and specific flybys in the dayside suggesting that our chemical model (for both neutral and ions) provides a good approximation of Titan's atmospheric chemistry as a whole. Our uncertainty propagation study highlights the difficulty to interpret the INMS mass spectra for masses 14, 31, 41 and we identified the key reactions responsible for these ambiguities. Despite an overall improvement in the chemical model, disagreement for some specific compounds (HC3N, C2H5CN, C2H4) highlights the role that certain physical processes could play
1D-3D hybrid modeling—from multi-compartment models to full resolution models in space and time
Grein, Stephan; Stepniewski, Martin; Reiter, Sebastian; Knodel, Markus M.; Queisser, Gillian
2014-01-01
Investigation of cellular and network dynamics in the brain by means of modeling and simulation has evolved into a highly interdisciplinary field, that uses sophisticated modeling and simulation approaches to understand distinct areas of brain function. Depending on the underlying complexity, these models vary in their level of detail, in order to cope with the attached computational cost. Hence for large network simulations, single neurons are typically reduced to time-dependent signal processors, dismissing the spatial aspect of each cell. For single cell or networks with relatively small numbers of neurons, general purpose simulators allow for space and time-dependent simulations of electrical signal processing, based on the cable equation theory. An emerging field in Computational Neuroscience encompasses a new level of detail by incorporating the full three-dimensional morphology of cells and organelles into three-dimensional, space and time-dependent, simulations. While every approach has its advantages and limitations, such as computational cost, integrated and methods-spanning simulation approaches, depending on the network size could establish new ways to investigate the brain. In this paper we present a hybrid simulation approach, that makes use of reduced 1D-models using e.g., the NEURON simulator—which couples to fully resolved models for simulating cellular and sub-cellular dynamics, including the detailed three-dimensional morphology of neurons and organelles. In order to couple 1D- and 3D-simulations, we present a geometry-, membrane potential- and intracellular concentration mapping framework, with which graph- based morphologies, e.g., in the swc- or hoc-format, are mapped to full surface and volume representations of the neuron and computational data from 1D-simulations can be used as boundary conditions for full 3D simulations and vice versa. Thus, established models and data, based on general purpose 1D-simulators, can be directly coupled to
CO2 conversion in a gliding arc plasma: 1D cylindrical discharge model
NASA Astrophysics Data System (ADS)
Wang, Weizong; Berthelot, Antonin; Kolev, Stanimir; Tu, Xin; Bogaerts, Annemie
2016-12-01
CO2 conversion by a gliding arc plasma is gaining increasing interest, but the underlying mechanisms for an energy-efficient process are still far from understood. Indeed, the chemical complexity of the non-equilibrium plasma poses a challenge for plasma modeling due to the huge computational load. In this paper, a one-dimensional (1D) gliding arc model is developed in a cylindrical frame, with a detailed non-equilibrium CO2 plasma chemistry set, including the CO2 vibrational kinetics up to the dissociation limit. The model solves a set of time-dependent continuity equations based on the chemical reactions, as well as the electron energy balance equation, and it assumes quasi-neutrality in the plasma. The loss of plasma species and heat due to convection by the transverse gas flow is accounted for by using a characteristic frequency of convective cooling, which depends on the gliding arc radius, the relative velocity of the gas flow with respect to the arc and on the arc elongation rate. The calculated values for plasma density and plasma temperature within this work are comparable with experimental data on gliding arc plasma reactors in the literature. Our calculation results indicate that excitation to the vibrational levels promotes efficient dissociation in the gliding arc, and this is consistent with experimental investigations of the gliding arc based CO2 conversion in the literature. Additionally, the dissociation of CO2 through collisions with O atoms has the largest contribution to CO2 splitting under the conditions studied. In addition to the above results, we also demonstrate that lumping the CO2 vibrational states can bring a significant reduction of the computational load. The latter opens up the way for 2D or 3D models with an accurate description of the CO2 vibrational kinetics.
Parameter sensitivities in a 1-D model for DMS and sulphur cycling in the upper ocean
NASA Astrophysics Data System (ADS)
Steiner, N.; Denman, K.
2008-07-01
We have developed a marine DMS (dimethylsulfide) module and implemented it in a 1-D coupled atmosphere-ocean-biogeochemical model. In developing the marine sulphur model we have found that several parameters used in the model are not known to even an order of magnitude. Our approach is used to test the model's sensitivity to these parameters. A parameter change of ±25% is applied to test the respective range of changes in the DMS fluxes. The model is run for a 3-year time period as well as for the time period of the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES) in July 2002. The simulated seasonal cycle is in agreement with available observations: Near surface DMS concentrations vary from 1.5nmolL-1 in winter to 13.5nmolL-1 in summer. Simulated DMS production is found to be most sensitive to variations of the S:N ratio and the bacterial consumption rate of DMS. Implementing light or UV limited bacterial activity shows a negligible effect in winter and increases DMS concentrations by 0.2- 0.6nmolL-1 in summer. Similarly a yield increase under UV stress increases summer values by 1- 2nmolL-1. The simulated diel cycle in surface DMS concentration is no more than 2.5nmolL-1, even when light-dependent changes in bacterial activity are considered. Simulating the DMS response to iron fertilization with the standard run leads to overestimation during an initial bloom of small phytoplankton. While implementing light-dependent bacterial activity has a minor effect, the implementation of yields that depend on nutrient availability significantly improves the results. The model confirms earlier results showing the importance of including atmospheric DMS concentrations in gas flux calculations when there are high surface concentrations and small atmospheric boundary layer heights. Simulated summer concentrations in the upper layer can be underestimated by 2nmolL-1 or more if the atmospheric concentration is set to zero. Our study shows that inclusion of
Open boundary conditions for the Diffuse Interface Model in 1-D
NASA Astrophysics Data System (ADS)
Desmarais, J. L.; Kuerten, J. G. M.
2014-04-01
New techniques are developed for solving multi-phase flows in unbounded domains using the Diffuse Interface Model in 1-D. They extend two open boundary conditions originally designed for the Navier-Stokes equations. The non-dimensional formulation of the DIM generalizes the approach to any fluid. The equations support a steady state whose analytical approximation close to the critical point depends only on temperature. This feature enables the use of detectors at the boundaries switching between conventional boundary conditions in bulk phases and a multi-phase strategy in interfacial regions. Moreover, the latter takes advantage of the steady state approximation to minimize the interface-boundary interactions. The techniques are applied to fluids experiencing a phase transition and where the interface between the phases travels through one of the boundaries. When the interface crossing the boundary is fully developed, the technique greatly improves results relative to cases where conventional boundary conditions can be used. Limitations appear when the interface crossing the boundary is not a stable equilibrium between the two phases: the terms responsible for creating the true balance between the phases perturb the interior solution. Both boundary conditions present good numerical stability properties: the error remains bounded when the initial conditions or the far field values are perturbed. For the PML, the influence of its main parameters on the global error is investigated to make a compromise between computational costs and maximum error. The approach can be extended to multiple spatial dimensions.
Modelling Hydrology of a Single Bioretention System with HYDRUS-1D
Meng, Yingying; Wang, Huixiao; Chen, Jiangang; Zhang, Shuhan
2014-01-01
A study was carried out on the effectiveness of bioretention systems to abate stormwater using computer simulation. The hydrologic performance was simulated for two bioretention cells using HYDRUS-1D, and the simulation results were verified by field data of nearly four years. Using the validated model, the optimization of design parameters of rainfall return period, filter media depth and type, and surface area was discussed. And the annual hydrologic performance of bioretention systems was further analyzed under the optimized parameters. The study reveals that bioretention systems with underdrains and impervious boundaries do have some detention capability, while their total water retention capability is extremely limited. Better detention capability is noted for smaller rainfall events, deeper filter media, and design storms with a return period smaller than 2 years, and a cost-effective filter media depth is recommended in bioretention design. Better hydrologic effectiveness is achieved with a higher hydraulic conductivity and ratio of the bioretention surface area to the catchment area, and filter media whose conductivity is between the conductivity of loamy sand and sandy loam, and a surface area of 10% of the catchment area is recommended. In the long-term simulation, both infiltration volume and evapotranspiration are critical for the total rainfall treatment in bioretention systems. PMID:25133240
Modelling hydrology of a single bioretention system with HYDRUS-1D.
Meng, Yingying; Wang, Huixiao; Chen, Jiangang; Zhang, Shuhan
2014-01-01
A study was carried out on the effectiveness of bioretention systems to abate stormwater using computer simulation. The hydrologic performance was simulated for two bioretention cells using HYDRUS-1D, and the simulation results were verified by field data of nearly four years. Using the validated model, the optimization of design parameters of rainfall return period, filter media depth and type, and surface area was discussed. And the annual hydrologic performance of bioretention systems was further analyzed under the optimized parameters. The study reveals that bioretention systems with underdrains and impervious boundaries do have some detention capability, while their total water retention capability is extremely limited. Better detention capability is noted for smaller rainfall events, deeper filter media, and design storms with a return period smaller than 2 years, and a cost-effective filter media depth is recommended in bioretention design. Better hydrologic effectiveness is achieved with a higher hydraulic conductivity and ratio of the bioretention surface area to the catchment area, and filter media whose conductivity is between the conductivity of loamy sand and sandy loam, and a surface area of 10% of the catchment area is recommended. In the long-term simulation, both infiltration volume and evapotranspiration are critical for the total rainfall treatment in bioretention systems.
Results and limits in the 1-D analytical modeling for the asymmetric DG SOI MOSFET
NASA Astrophysics Data System (ADS)
Cobianu, O.; Glesner, M.
2008-05-01
This paper presents the results and the limits of 1-D analytical modeling of electrostatic potential in the low-doped p type silicon body of the asymmetric n-channel DG SOI MOSFET, where the contribution to the asymmetry comes only from p- and n-type doping of polysilicon used as the gate electrodes. Solving Poisson's equation with boundary conditions based on the continuity of normal electrical displacement at interfaces and the presence of a minimum electrostatic potential by using the Matlab code we have obtained a minimum potential with a slow variation in the central zone of silicon with the value pinned around 0.46 V, where the applied VGS voltage varies from 0.45 V to 0.95 V. The paper states clearly the validity domain of the analytical solution and the important effect of the localization of the minimum electrostatic potential value on the potential variation at interfaces as a function of the applied VGS voltage.
1D and 2D urban dam-break flood modelling in Istanbul, Turkey
NASA Astrophysics Data System (ADS)
Ozdemir, Hasan; Neal, Jeffrey; Bates, Paul; Döker, Fatih
2014-05-01
Urban flood events are increasing in frequency and severity as a consequence of several factors such as reduced infiltration capacities due to continued watershed development, increased construction in flood prone areas due to population growth, the possible amplification of rainfall intensity due to climate change, sea level rise which threatens coastal development, and poorly engineered flood control infrastructure (Gallegos et al., 2009). These factors will contribute to increased urban flood risk in the future, and as a result improved modelling of urban flooding according to different causative factor has been identified as a research priority (Gallegos et al., 2009; Ozdemir et al. 2013). The flooding disaster caused by dam failures is always a threat against lives and properties especially in urban environments. Therefore, the prediction of dynamics of dam-break flows plays a vital role in the forecast and evaluation of flooding disasters, and is of long-standing interest for researchers. Flooding occurred on the Ayamama River (Istanbul-Turkey) due to high intensity rainfall and dam-breaching of Ata Pond in 9th September 2009. The settlements, industrial areas and transportation system on the floodplain of the Ayamama River were inundated. Therefore, 32 people were dead and millions of Euros economic loses were occurred. The aim of this study is 1 and 2-Dimensional flood modelling of the Ata Pond breaching using HEC-RAS and LISFLOOD-Roe models and comparison of the model results using the real flood extent. The HEC-RAS model solves the full 1-D Saint Venant equations for unsteady open channel flow whereas LISFLOOD-Roe is the 2-D shallow water model which calculates the flow according to the complete Saint Venant formulation (Villanueva and Wright, 2006; Neal et al., 2011). The model consists a shock capturing Godunov-type scheme based on the Roe Riemann solver (Roe, 1981). 3 m high resolution Digital Surface Model (DSM), natural characteristics of the pond
Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes
NASA Astrophysics Data System (ADS)
Johnson, R. H.; Morrison, S.; Morris, S.; Tigar, A.; Dam, W. L.; Dayvault, J.
2015-12-01
At many U.S. Department of Energy Office of Legacy Management sites, 100 year natural flushing was selected as a remedial option for groundwater uranium plumes. However, current data indicate that natural flushing is not occurring as quickly as expected and solid-phase and aqueous uranium concentrations are persistent. At the Grand Junction, Colorado office site, column testing was completed on core collected below an area where uranium mill tailings have been removed. The total uranium concentration in this core was 13.2 mg/kg and the column was flushed with laboratory-created water with no uranium and chemistry similar to the nearby Gunnison River. The core was flushed for a total of 91 pore volumes producing a maximum effluent uranium concentration of 6,110 μg/L at 2.1 pore volumes and a minimum uranium concentration of 36.2 μg/L at the final pore volume. These results indicate complex geochemical reactions at small pore volumes and a long tailing affect at greater pore volumes. Stop flow data indicate the occurrence of non-equilibrium processes that create uranium concentration rebound. These data confirm the potential for plume persistence, which is occurring at the field scale. 1D reactive transport modeling was completed using PHREEQC (geochemical model) and calibrated to the column test data manually and using PEST (inverse modeling calibration routine). Processes of sorption, dual porosity with diffusion, mineral dissolution, dispersion, and cation exchange were evaluated separately and in combination. The calibration results indicate that sorption and dual porosity are major processes in explaining the column test data. These processes are also supported by fission track photographs that show solid-phase uranium residing in less mobile pore spaces. These procedures provide valuable information on plume persistence and secondary source processes that may be used to better inform and evaluate remedial strategies, including natural flushing.
1-D/3-D geologic model of the Western Canada Sedimentary Basin
Higley, D.K.; Henry, M.; Roberts, L.N.R.; Steinshouer, D.W.
2005-01-01
The 3-D geologic model of the Western Canada Sedimentary Basin comprises 18 stacked intervals from the base of the Devonian Woodbend Group and age equivalent formations to ground surface; it includes an estimated thickness of eroded sediments based on 1-D burial history reconstructions for 33 wells across the study area. Each interval for the construction of the 3-D model was chosen on the basis of whether it is primarily composed of petroleum system elements of reservoir, hydrocarbon source, seal, overburden, or underburden strata, as well as the quality and areal distribution of well and other data. Preliminary results of the modeling support the following interpretations. Long-distance migration of hydrocarbons east of the Rocky Mountains is indicated by oil and gas accumulations in areas within which source rocks are thermally immature for oil and (or) gas. Petroleum systems in the basin are segmented by the northeast-trending Sweetgrass Arch; hydrocarbons west of the arch were from source rocks lying near or beneath the Rocky Mountains, whereas oil and gas east of the arch were sourced from the Williston Basin. Hydrocarbon generation and migration are primarily due to increased burial associated with the Laramide Orogeny. Hydrocarbon sources and migration were also influenced by the Lower Cretaceous sub-Mannville unconformity. In the Peace River Arch area of northern Alberta, Jurassic and older formations exhibit high-angle truncations against the unconformity. Potential Paleozoic though Mesozoic hydrocarbon source rocks are in contact with overlying Mannville Group reservoir facies. In contrast, in Saskatchewan and southern Alberta the contacts are parallel to sub-parallel, with the result that hydrocarbon source rocks are separated from the Mannville Group by seal-forming strata within the Jurassic. Vertical and lateral movement of hydrocarbons along the faults in the Rocky Mountains deformed belt probably also resulted in mixing of oil and gas from numerous
Correlation models for waste tank sludges and slurries
Mahoney, L.A.; Trent, D.S.
1995-07-01
This report presents the results of work conducted to support the TEMPEST computer modeling under the Flammable Gas Program (FGP) and to further the comprehension of the physical processes occurring in the Hanford waste tanks. The end products of this task are correlation models (sets of algorithms) that can be added to the TEMPEST computer code to improve the reliability of its simulation of the physical processes that occur in Hanford tanks. The correlation models can be used to augment, not only the TEMPEST code, but other computer codes that can simulate sludge motion and flammable gas retention. This report presents the correlation models, also termed submodels, that have been developed to date. The submodel-development process is an ongoing effort designed to increase our understanding of sludge behavior and improve our ability to realistically simulate the sludge fluid characteristics that have an impact on safety analysis. The effort has employed both literature searches and data correlation to provide an encyclopedia of tank waste properties in forms that are relatively easy to use in modeling waste behavior. These properties submodels will be used in other tasks to simulate waste behavior in the tanks. Density, viscosity, yield strength, surface tension, heat capacity, thermal conductivity, salt solubility, and ammonia and water vapor pressures were compiled for solutions and suspensions of sodium nitrate and other salts (where data were available), and the data were correlated by linear regression. In addition, data for simulated Hanford waste tank supernatant were correlated to provide density, solubility, surface tension, and vapor pressure submodels for multi-component solutions containing sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate.
McLaren, J.M.
1993-12-01
During the middle to late 1950`s, a program was begun to concentrate the radioactive waste products of the uranium and plutonium recovery processes. This program used sodium nickel ferrocyanide to precipitate radioactive cesium from the waste streams. The precipitate was then stored in large, underground single-shell tanks at the Hanford Site in south central Washington. Several of the tanks have been stabilized, a process that included removing as much pumpable liquid as possible from the tanks. This liquid contained heat-producing radionuclides. Because of the many transfers involved, the lack of accurate inventory data for the various waste streams, and the absence of a need for an accurate value of the heat load, the heat loads of the ferrocyanide waste storage tanks have only been estimated. As a result of the intense radiation field within these tanks, the chemical content of the waste has changed. This, coupled with the fact that the characteristics of the input waste were not well known, has resulted in uncertainty in the thermal characteristics of the stored sludge. All of these parameters are needed to evaluate the safety of these tanks. The purposes of this report are to document the updated thermal analysis model for ferrocyanide tanks and to use the model to determine the heat load of Tank 241-BY-104. This new model utilizes several new parameters and a new technique, which are described in this report. The new model is considered more accurate than the previous model, and all future thermal analyses of ferrocyanide tanks will use this updated model.
A 1-D radiative conductive model to study the SOIR/VEx thermal profiles
NASA Astrophysics Data System (ADS)
Mahieux, Arnaud; Erwin, Justin T.; Chamberlain, Sarah; Robert, Séverine; Carine Vandaele, Ann; Wilquet, Valérie; Thomas, Ian; Yelle, Roger V.; Bertaux, Jean-Loup
2015-04-01
SOIR is an infrared spectrometer on board Venus Express that probes the Venus terminator region since 2006. The measurements are taken on the morning and evening sides of the terminator, covering all latitudes from the North Pole to the South Pole. Its wavelength range - 2.2 to 4.3 μm - allows a detailed chemical inventory of the Venus atmosphere [1-5], such as CO2, CO, H2O, HCl, HF, SO2 and aerosols. CO2 is detected from 70 km up to 165 km, CO from 70 km to 140 km, and the minor species typically below 110 km down to 70 km. Number density profiles of these species are computed from the measured spectra. Temperature profiles are obtained while computing the spectral inversion of the CO2 spectra combined with the hydrostatic law [6]. These temperature measurements show a striking permanent temperature minimum (at 125 km) and a weaker temperature maximum (over 100-115 km). The time variability of the CO2 density profiles spans over two orders of magnitude, and a clear trend is seen with latitude. The temperature variations are also important, of the order of 35 K for a given pressure level, but the latitude variation are small. Miss-RT, a 1D radiative transfer model has been developed to reproduce the SOIR terminator profiles, derived from the Mars thermosphere code presented in [7]. This model has been expanded to better account for the CO2, CO, and O non-LTE radiative heating and cooling processes which have to be considered in the dense atmosphere of Venus. Radiative cooling by minor species detected by SOIR (e.g. HCl, SO2, and H2O) are found to be small in comparison to the 15 μm CO2 cooling. Aerosol cooling in the 60-90km altitude range may be important to the thermal balance. There is a good agreement between the 1D model temperature profile and the mean SOIR temperature profile. Further we can suggest parameters that can be adjusted to improve the agreement between the model and measurements. The remaining differences can be attributed to the atmosphere
Dynamical Models of SAURON and CALIFA Galaxies: 1D and 2D Rotational Curves
NASA Astrophysics Data System (ADS)
Kalinova, Veselina; van de Ven, G.; Lyubenova, M.; Falcon-Barroso, J.; van den Bosch, R.
2013-01-01
The mass of a galaxy is the most important parameter to understand its structure and evolution. The total mass we can infer by constructing dynamical models that fit the motion of the stars and gas in the galaxy. The dark matter content then follows after subtracting the luminous matter inferred from colors and/or spectra. Here, we present the mass distribution of a sample of 18 late-type spiral (Sb-Sd) galaxies, using two-dimensional stellar kinematics obtained with the integral-field spectrograph SAURON. The observed second order velocity moments of these galaxies are fitted with solutions of the Axisymmetric Jeans equations and give us an accurate estimation of the mass-to-light ratio profiles and rotational curves. The rotation curves of the galaxies are obtained by the Asymmetric Drift Correction (ADC) and Multi-Gaussian Expansion (MGE) methods, corresponding to one- and two-dimensional mass distribution. Their comparison shows that the mass distribution based on the 2D stellar kinematics is much more reliable than 1D one. SAURON integral field of view looks at the inner parts of the galaxies in contrast with CALIFA survey. CALIFA survey provides PMAS/PPAK integral-field spectroscopic data of ~ 600 nearby galaxies as part of the Calar Alto Legacy Integral Field Area. We show the first CALIFA dynamical models of different morphological type of galaxies, giving the clue about the mass distribution of galaxies through the whole Hubble sequence and their evolution from the blue cloud to the red sequence.
NASA Astrophysics Data System (ADS)
Choi, Sanghun; Choi, Jiwoong; Hoffman, Eric; Lin, Ching-Long
2016-11-01
To predict the proper relationship between airway resistance and regional airflow, we proposed a novel 1-D network model for airway resistance and acinar compliance. First, we extracted 1-D skeletons at inspiration images, and generated 1-D trees of CT unresolved airways with a volume filling method. We used Horsfield order with random heterogeneity to create diameters of the generated 1-D trees. We employed a resistance model that accounts for kinetic energy and viscous dissipation (Model A). The resistance model is further coupled with a regional compliance model estimated from two static images (Model B). For validation, we applied both models to a healthy subject. The results showed that Model A failed to provide airflows consistent with air volume change, whereas Model B provided airflows consistent with air volume change. Since airflows shall be regionally consistent with air volume change in patients with normal airways, Model B was validated. Then, we applied Model B to severe asthmatic subjects. The results showed that regional airflows were significantly deviated from air volume change due to airway narrowing. This implies that airway resistance plays a major role in determining regional airflows of patients with airway narrowing. Support for this study was provided, in part, by NIH Grants U01 HL114494, R01 HL094315, R01 HL112986, and S10 RR022421.
Epstein, Sally; Willemet, Marie; Chowienczyk, Phil J; Alastruey, Jordi
2015-07-01
Patient-specific one-dimensional (1D) blood flow modeling requires estimating model parameters from available clinical data, ideally acquired noninvasively. The larger the number of arterial segments in a distributed 1D model, the greater the number of input parameters that need to be estimated. We investigated the effect of a reduction in the number of arterial segments in a given distributed 1D model on the shape of the simulated pressure and flow waveforms. This is achieved by systematically lumping peripheral 1D model branches into windkessel models that preserve the net resistance and total compliance of the original model. We applied our methodology to a model of the 55 larger systemic arteries in the human and to an extended 67-artery model that contains the digital arteries that perfuse the fingers. Results show good agreement in the shape of the aortic and digital waveforms between the original 55-artery (67-artery) and reduced 21-artery (37-artery) models. Reducing the number of segments also enables us to investigate the effect of arterial network topology (and hence reflection sites) on the shape of waveforms. Results show that wave reflections in the thoracic aorta and renal arteries play an important role in shaping the aortic pressure and flow waves and in generating the second peak of the digital pressure and flow waves. Our novel methodology is important to simplify the computational domain while maintaining the precision of the numerical predictions and to assess the effect of wave reflections.
Epstein, Sally; Willemet, Marie; Chowienczyk, Phil J.
2015-01-01
Patient-specific one-dimensional (1D) blood flow modeling requires estimating model parameters from available clinical data, ideally acquired noninvasively. The larger the number of arterial segments in a distributed 1D model, the greater the number of input parameters that need to be estimated. We investigated the effect of a reduction in the number of arterial segments in a given distributed 1D model on the shape of the simulated pressure and flow waveforms. This is achieved by systematically lumping peripheral 1D model branches into windkessel models that preserve the net resistance and total compliance of the original model. We applied our methodology to a model of the 55 larger systemic arteries in the human and to an extended 67-artery model that contains the digital arteries that perfuse the fingers. Results show good agreement in the shape of the aortic and digital waveforms between the original 55-artery (67-artery) and reduced 21-artery (37-artery) models. Reducing the number of segments also enables us to investigate the effect of arterial network topology (and hence reflection sites) on the shape of waveforms. Results show that wave reflections in the thoracic aorta and renal arteries play an important role in shaping the aortic pressure and flow waves and in generating the second peak of the digital pressure and flow waves. Our novel methodology is important to simplify the computational domain while maintaining the precision of the numerical predictions and to assess the effect of wave reflections. PMID:25888513
PORFLOW Modeling Supporting The H-Tank Farm Performance Assessment
Jordan, J. M.; Flach, G. P.; Westbrook, M. L.
2012-08-31
Numerical simulations of groundwater flow and contaminant transport in the vadose and saturated zones have been conducted using the PORFLOW code in support of an overall Performance Assessment (PA) of the H-Tank Farm. This report provides technical detail on selected aspects of PORFLOW model development and describes the structure of the associated electronic files. The PORFLOW models for the H-Tank Farm PA, Rev. 1 were updated with grout, solubility, and inventory changes. The aquifer model was refined. In addition, a set of flow sensitivity runs were performed to allow flow to be varied in the related probabilistic GoldSim models. The final PORFLOW concentration values are used as input into a GoldSim dose calculator.
Development of a 1D canopy module to couple mesoscale meteorogical model with building energy model
NASA Astrophysics Data System (ADS)
Mauree, Dasaraden; Kohler, Manon; Blond, Nadège; Clappier, Alain
2013-04-01
The actual global warming, highlighted by the scientific community, is due to the greenhouse gases emissions resulting from our energy consumption. This energy is mainly produced in cities (about 70% of the total energy use). Around 36% of this energy are used in buildings (residential/tertiary) and this accounts for about 20% of the greenhouse gases emissions. Moreover, the world population is more and more concentrated in urban areas, 50% of the actual world population already lives in cities and this ratio is expected to reach 70% by 2050. With the obviously increasing responsibility of cities in climate change in the future, it is of great importance to go toward more sustainable cities that would reduce the energy consumption in urban areas. The energy use inside buildings is driven by two factors: (1) the level of comfort wished by the inhabitants and (2) the urban climate. On the other hand, the urban climate is influenced by the presence of buildings. Indeed, artificial surfaces of urban areas modify the energy budget of the Earth's surface and furthermore, heat is released into the atmosphere due to the energy used by buildings. Modifications at the building scale (micro-scale) can thus have an influence on the climate of the urban areas and surroundings (meso-scale), and vice and versa. During the last decades, meso-scale models have been developed to simulate the atmospheric conditions for domain of 100-1000km wide with a resolution of few kilometers. Due to their low resolution, the effects of small obstacles (such as buildings, trees, ...) near the ground are not reproduced properly and parameterizations have been developed to represent such effects in meso-scale models. On the other side, micro-scale models have a higher resolution (around 1 meter) and consequently can better simulate the impact of obstacles on the atmospheric heat flux exchanges with the earth surface. However, only a smaller domain (less than 1km) can be simulated for the same
Diesel Engine performance improvement in a 1-D engine model using Particle Swarm Optimization
NASA Astrophysics Data System (ADS)
Karra, Prashanth
2015-12-01
A particle swarm optimization (PSO) technique was implemented to improve the engine development and optimization process to simultaneously reduce emissions and improve the fuel efficiency. The optimization was performed on a 4-stroke 4-cylinder GT-Power based 1-D diesel engine model. To achieve the multi-objective optimization, a merit function was defined which included the parameters to be optimized: Nitrogen Oxides (NOx), Nonmethyl hydro carbons (NMHC), Carbon Monoxide (CO), Brake Specific Fuel Consumption (BSFC). EPA Tier 3 emissions standards for non-road diesel engines between 37 and 75 kW of output were chosen as targets for the optimization. The combustion parameters analyzed in this study include: Start of main Injection, Start of Pilot Injection, Pilot fuel quantity, Swirl, and Tumble. The PSO was found to be very effective in quickly arriving at a solution that met the target criteria as defined in the merit function. The optimization took around 40-50 runs to find the most favourable engine operating condition under the constraints specified in the optimization. In a favourable case with a high merit function values, the NOx+NMHC and CO values were reduced to as low as 2.9 and 0.014 g/kWh, respectively. The operating conditions at this point were: 10 ATDC Main SOI, -25 ATDC Pilot SOI, 0.25 mg of pilot fuel, 0.45 Swirl and 0.85 tumble. These results indicate that late main injections preceded by a close, small pilot injection are most favourable conditions at the operating condition tested.
1D fluid model of the dielectric barrier discharge in chlorine
NASA Astrophysics Data System (ADS)
Avtaeva, Svetlana
2016-09-01
The 1D fluid model of the dielectric barrier discharge (DBD) in pure chlorine is developed. The discharge is excited in 8 mm gas gap between quartz dielectric layers of 2 mm thickness covered metallic electrodes. The source voltage US =U0 sin ωt with a frequency 100 kHz and amplitude 8 kV is applied to the electrodes. Chlorine pressure is varied from 15 to 100 Torr. At pressure of 15 Torr a breakdown appears with voltage drop across the discharge gap about 1 kV whereas at 100 Torr it appears with voltage drop about 2 kV. After the first current spike some lower current spikes are observes with chlorine pressure of 100 Torr and large in number current spikes of about identical magnitude are observed with the pressure of 15 Torr. The maximal current density at all pressures reaches about 4 mA/cm.2Total density of surface charge deposited on the electrodes during a half-cycle decreases with chlorine pressure because duration of the current spike discharge phase reduces with chlorine pressure. The average power density inputted in the discharge is 2.5-5.8 W/cm3 per a cycle. The Cl2 plasma is electronegative, the most abundant ions are Cl2+and Cl-. It is shown, that ions get about 95% of the discharge power as electrons get about 5% of the discharge power. 67-97% of the electron power is spending for dissociation and ionization of Cl2 molecules. Emission of Cl* atoms and Cl2*molecules is weak.
Testing the early Mars H2-CO2 greenhouse hypothesis with a 1-D photochemical model
NASA Astrophysics Data System (ADS)
Batalha, Natasha; Domagal-Goldman, Shawn D.; Ramirez, Ramses; Kasting, James F.
2015-09-01
A recent study by Ramirez et al. (Ramirez, R.M. et al. [2014]. Nat. Geosci. 7(1), 59-63. http://www.nature.com/doifinder/10.1038/ngeo2000 (accessed 16.09.14)) demonstrated that an atmosphere with 1.3-4 bar of CO2 and H2O, in addition to 5-20% H2, could have raised the mean annual and global surface temperature of early Mars above the freezing point of water. Such warm temperatures appear necessary to generate the rainfall (or snowfall) amounts required to carve the ancient martian valleys. Here, we use our best estimates for early martian outgassing rates, along with a 1-D photochemical model, to assess the conversion efficiency of CO, CH4, and H2S to CO2, SO2, and H2. Our outgassing estimates assume that Mars was actively recycling volatiles between its crust and interior, as Earth does today. H2 production from serpentinization and deposition of banded iron-formations is also considered. Under these assumptions, maintaining an H2 concentration of ˜1-2% by volume is achievable, but reaching 5% H2 requires additional H2 sources or a slowing of the hydrogen escape rate below the diffusion limit. If the early martian atmosphere was indeed H2-rich, we might be able to see evidence of this in the rock record. The hypothesis proposed here is consistent with new data from the Curiosity Rover, which show evidence for a long-lived lake in Gale Crater near Mt. Sharp. It is also consistent with measured oxygen fugacities of martian meteorites, which show evidence for progressive mantle oxidation over time.
A 1-D modelling of climatic and chemical effects of greenhouse gases
NASA Astrophysics Data System (ADS)
Vupputuri, R. K. R.; Higuchi, K.; Hengeveld, H. G.
1995-09-01
A coupled 1-D time-dependent radiative-convective-photochemical diffusion model which extends from the surface to 60 km is used to investigate the potential impact of greenhouse trace gas emissions on long-term changes in global climate, atmospheric ozone and surface UV-B radiation, taking into accoont the influence of aerosol loading into the atmosphere from major volcanic eruptions, of thermal inertia of the upper mixed layer of the ocean and of other radiativephotochemical feedback mechanisms. Experiments are carried out under global and annual average insolation and cloudiness conditions. The transient calculations are made for three different growth scenarios for increase in trace gas concentrations. Scenario 1, which begins in 1850, uses the best estimate values for future trace gas concentrations of CO2, CH4, N2O, CFC-11, CFC-12 and tropospheric O3, based on current observational trends. Scenarios 2 and 3, which begin in 1990, assume lower and upper ranges, respectively, of observed growth rates to estimate future concentrations. The transient response of the model for Scenario 1 suggests that surface warming of the ocean mixed layer of about 1 K should have taken place between 1850 and 1990 due to a combined increase of atmospheric CO2 and other trace gases. For the three scenarios considered in this study, the cumulative surface warming induced by all major trace gases for the period 1850 to 2080 ranges from 2.7 K to 8.2 K with the best estimate value of 5 K. The results indicate that the direct and the indirect chemistry-climate interactions of non-CO2 trace gases contribute significantly to the cumulative surface warming (up to 65% by the year 2080). The thermal inertia of a mixed layer of the ocean is shown to have the effect of delaying equilibrium surface warming by almost three decades with an e-folding time of about 5 years. The volcanic aerosols which would result from major volcanic eruptions play a significant role by interrupting the long
ABSTRACTION OF INFORMATION FROM 2- AND 3-DIMENSIONAL PORFLOW MODELS INTO A 1-D GOLDSIM MODEL - 11404
Taylor, G.; Hiergesell, R.
2010-11-16
The Savannah River National Laboratory has developed a 'hybrid' approach to Performance Assessment modeling which has been used for a number of Performance Assessments. This hybrid approach uses a multi-dimensional modeling platform (PorFlow) to develop deterministic flow fields and perform contaminant transport. The GoldSim modeling platform is used to develop the Sensitivity and Uncertainty analyses. Because these codes are performing complementary tasks, it is incumbent upon them that for the deterministic cases they produce very similar results. This paper discusses two very different waste forms, one with no engineered barriers and one with engineered barriers, each of which present different challenges to the abstraction of data. The hybrid approach to Performance Assessment modeling used at the SRNL uses a 2-D unsaturated zone (UZ) and a 3-D saturated zone (SZ) model in the PorFlow modeling platform. The UZ model consists of the waste zone and the unsaturated zoned between the waste zone and the water table. The SZ model consists of source cells beneath the waste form to the points of interest. Both models contain 'buffer' cells so that modeling domain boundaries do not adversely affect the calculation. The information pipeline between the two models is the contaminant flux. The domain contaminant flux, typically in units of moles (or Curies) per year from the UZ model is used as a boundary condition for the source cells in the SZ. The GoldSim modeling component of the hybrid approach is an integrated UZ-SZ model. The model is a 1-D representation of the SZ, typically 1-D in the UZ, but as discussed below, depending on the waste form being analyzed may contain pseudo-2-D elements. A waste form at the Savannah River Site (SRS) which has no engineered barriers is commonly referred to as a slit trench. A slit trench, as its name implies, is an unlined trench, typically 6 m deep, 6 m wide, and 200 m long. Low level waste consisting of soil, debris, rubble, wood
Hanford Tank 241-C-103 Residual Waste Contaminant Release Models and Supporting Data
Cantrell, Kirk J.; Krupka, Kenneth M.; Deutsch, William J.; Lindberg, Michael J.; Schaef, Herbert T.; Geiszler, Keith N.; Arey, Bruce W.
2008-01-15
This report tabulates data generated by laboratory characterization and testing of three samples collected from tank C-103. The data presented here will form the basis for a release model that will be developed for tank C-103. These release models are being developed to support the tank risk assessments performed by CH2M HILL Hanford Group, Inc. for DOE.
1D Runoff-runon stochastic model in the light of queueing theory : heterogeneity and connectivity
NASA Astrophysics Data System (ADS)
Harel, M.-A.; Mouche, E.; Ledoux, E.
2012-04-01
Runoff production on a hillslope during a rainfall event may be simplified as follows. Given a soil of constant infiltrability I, which is the maximum amount of water that the soil can infiltrate, and a constant rainfall intensity R, runoff is observed where R is greater than I. The infiltration rate equals the infiltrability when runoff is produced, R otherwise. When ponding time, topography, and overall spatial and temporal variations of physical parameters, such as R and I, are neglected, the runoff equation remains simple. In this study, we consider soils of spatially variable infiltrability. As runoff can re-infiltrate on down-slope areas of higher infiltrabilities (runon), the resulting process is highly non-linear. The stationary runoff equation is: Qn+1 = max(Qn + (R - In)*Δx , 0) where Qn is the runoff arriving on pixel n of size Δx [L2/T], R and In the rainfall intensity and infiltrability on that same pixel [L/T]. The non-linearity is due to the dependence of infiltration on R and Qn, that is runon. This re-infiltration process generates patterns of runoff along the slope, patterns that organise and connect to each other differently depending on the rainfall intensity and the nature of the soil heterogeneity. The runoff connectivity, assessed using the connectivity function of Allard (1993), affects greatly the dynamics of the runoff hillslope. Our aim is to assess, in a stochastic framework, the runoff organization on 1D slopes with random infiltrabilities (log-normal, exponential, bimodal and uniform distributions) by means of theoretical developments and numerical simulations. This means linking the nature of soil heterogeneity with the resulting runoff organisation. In term of connectivity, we investigate the relations between structural (infiltrability) and functional (runoff) connectivity. A theoretical framework based on the queueing theory is developed. We implement the idea of Jones et al. (2009), who remarked that the above formulation is
1996-04-01
This report presents the results of a modeling-needs assessment conducted for Tank Farm Operations at the Hanford Site. The goal of this project is to integrate geophysical logging and subsurface transport modeling into a broader decision-based framework that will be made available to guide Tank Farm Operations in implementing future modeling studies. In support of this goal, previous subsurface transport modeling studies were reviewed, and stakeholder surveys and interviews were completed (1) to identify regulatory, stakeholder, and Native American concerns and the impacts of these concerns on Tank Farm Operations, (2) to identify technical constraints that impact site characterization and modeling efforts, and (3) to assess how subsurface transport modeling can best be used to support regulatory, stakeholder, Native American, and Tank Farm Operations needs. This report is organized into six sections. Following an introduction, Section 2.0 discusses background issues that relate to Tank Farm Operations. Section 3.0 summarizes the technical approach used to appraise the status of modeling and supporting characterization. Section 4.0 presents a detailed description of how the technical approach was implemented. Section 5.0 identifies findings and observations that relate to implementation of numerical modeling, and Section 6.0 presents recommendations for future activities.
Sabtaji, Agung E-mail: agung.sabtaji@bmkg.go.id; Nugraha, Andri Dian
2015-04-24
West Papua region has fairly high of seismicity activities due to tectonic setting and many inland faults. In addition, the region has a unique and complex tectonic conditions and this situation lead to high potency of seismic hazard in the region. The precise earthquake hypocenter location is very important, which could provide high quality of earthquake parameter information and the subsurface structure in this region to the society. We conducted 1-D P-wave velocity using earthquake data catalog from BMKG for April, 2009 up to March, 2014 around West Papua region. The obtained 1-D seismic velocity then was used as input for improving hypocenter location using double-difference method. The relocated hypocenter location shows fairly clearly the pattern of intraslab earthquake beneath New Guinea Trench (NGT). The relocated hypocenters related to the inland fault are also observed more focus in location around the fault.
A One-Dimensional (1-D) Three-Region Model for a Bubbling Fluidized-Bed Adsorber
Lee, Andrew; Miller, David C.
2012-01-01
A general one-dimensional (1-D), three-region model for a bubbling fluidized-bed adsorber with internal heat exchangers has been developed. The model can predict the hydrodynamics of the bed and provides axial profiles for all temperatures, concentrations, and velocities. The model is computationally fast and flexible and allows for any system of adsorption and desorption reactions to be modeled, making the model applicable to any adsorption process. The model has been implemented in both gPROMS and Aspen Custom Modeler, and the behavior of the model has been verified.
Numerical Modeling of Pressurization of a Propellant Tank
NASA Technical Reports Server (NTRS)
Majumdar, Alok; Steadman, Todd
1998-01-01
An unsteady finite volume procedure has been developed to predict the history of pressure, temperature and mass flow rate of the pressurant and propellant during the expulsion of the propellant from a tank. The time dependent mass, momentum and energy conservation equations are solved at the ullage space. The model accounts for the change in the ullage volume due to expulsion of the propellant. It also accounts for the heat transfer from the tank wall and propellant to the ullage gas. The procedure was incorporated in the Generalized Fluid System Simulation Program (GFSSP). The results of several test cases were then compared with a published correlation of pressurant requirements for a given displacement of propellant. The agreement between the predictions and the correlation was found to be satisfactory.
Erosion Modeling Analysis For Modified DWPF SME Tank
LEE, SI
2004-05-03
In support of an erosion evaluation for the modified cooling coil guide and its supporting structure in the DWPF SME vessel, a computational model was developed to identify potential sites of high erosion using the same methodology established by previous work. The erosion mechanism identified in the previous work was applied to the evaluation of high erosion locations representative of the actual flow process in the modified coil guide of the SME vessel, abrasive erosion which occurs by high wall shear of viscous liquid. The results show that primary locations of the highest erosion due to the abrasive wall erosion are at the leading edge of the guide, external surface of the insert plate, the tank floor next to the insert plate of the coil guide support, and the upstream lead-in plate. The present modeling results show a good comparison between the original and the modified cases in terms of high erosion sites, as well as the degree of erosion and the calculated shear stress. Wall she ar of the tank floor is reduced by about 30 per cent because of the new coil support plate. Calculations for the impeller speed lower than 103 rpm in the SME showed similar erosion patterns but significantly reduced wall shear stresses and reduced overall erosion. Comparisons of the 103 rpm results with SME measurements indicated that no significant erosion of the tank floor in the SME is to be expected. Thus, it is recommended that the agitator speed of SME does not exceed 103 rpm.
SAMPLE AOR CALCULATION USING ANSYS FULL PARAMETRIC MODEL FOR TANK SST-SX
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS parametric 360-degree model for single-shell tank SX and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric full model for the single shell tank (SST) SX to deal with asymmetry loading conditions and provide a sample analysis of the SST-SX tank based on analysis of record (AOR) loads. The SST-SX model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS SLICE PARAMETRIC MODEL FOR TANK SST-SX
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS slice parametric model for single-shell tank SX and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for the single shell tank (SST) SX, and provide a sample analysis of the SST-SX tank based on analysis of record (AOR) loads. The SST-SX model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS AXISYMMETRIC PARAMETRIC MODEL FOR TANK SST-S
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS axisymmetric parametric model for single-shell tank S and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for single shell tank (SST) S, and provide a sample analysis of SST-S tank based on analysis of record (AOR) loads. The SST-S model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS SLICE PARAMETRIC MODEL FOR TANK SST-BX
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS slice parametric model for single-shell tank BX and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for the single shell tank (SST) BX, and provide a sample analysis of the SST-BX tank based on analysis of record (AOR) loads. The SST-BX model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS SLICE PARAMETRIC MODEL FOR TANK SST-A
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS slice parametric model for single-shell tank A and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for the single shell tank (S) A, and provide a sample analysis of the SST-S tank based on analysis of record (AOR) loads. The SST-A model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS AXISYMMETRIC PARAMETRIC MODEL FOR TANK SST-AX
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS axisymmetric parametric model for single-shell tank AX and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for single shell tank (SST) AX, and provide a sample analysis of SST-AX tank based on analysis of record (AOR) loads. The SST-AX model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS SLICE PARAMETRIC MODEL FOR TANK SST-S
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS slice parametric model for single-shell tank S and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for the single shell tank (SST) S, and provide a sample analysis of the SST-S tank based on analysis of record (AOR) loads. The SST-S model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS SLICE PARAMETRIC MODEL FOR TANK SST-AX
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS slice parametric model for single-shell tank AX and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for the single shell tank (SST) AX, and provide a sample analysis of the SST-AX tank based on analysis of record (AOR) loads. The SST-AX model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS AXISYMMETRIC PARAMETRIC MODEL FOR TANK SST-SX
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS axisymmetric parametric model for single-shell tank SX and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for single shell tank (SST) SX, and provide a sample analysis of the SST-SX tank based on analysis of record (AOR) loads. The SST-SX model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
SAMPLE AOR CALCULATION USING ANSYS AXISYMMETRIC PARAMETRIC MODEL FOR TANK SST-A
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS axisymmetric parametric model for single-shell tank A and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to develop a parametric model for single shell tank (SST) A, and provide a sample analysis of SST-A tank based on analysis of record (AOR) loads. The SST-A model is based on buyer-supplied as-built drawings and information for the AOR for SSTs, encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
Marin-Valencia, Isaac; Good, Levi B.; Ma, Qian; Duarte, Joao; Bottiglieri, Teodoro; Sinton, Christopher M.; Heilig, Charles W.; Pascual, Juan M.
2012-01-01
Brain glucose supplies most of the carbon required for acetyl-coenzyme A (acetyl-CoA) generation (an important step for myelin synthesis) and for neurotransmitter production via further metabolism of acetyl-CoA in the tricarboxylic acid (TCA) cycle. However, it is not known whether reduced brain glucose transporter type I (GLUT-1) activity, the hallmark of the GLUT-1 deficiency (G1D) syndrome, leads to acetyl-CoA, TCA or neurotransmitter depletion. This question is relevant because, in its most common form in man, G1D is associated with cerebral hypomyelination (manifested as microcephaly) and epilepsy, suggestive of acetyl-CoA depletion and neurotransmitter dysfunction, respectively. Yet, brain metabolism in G1D remains underexplored both theoretically and experimentally, partly because computational models of limited brain glucose transport are subordinate to metabolic assumptions and partly because current hemizygous G1D mouse models manifest a mild phenotype not easily amenable to investigation. In contrast, adult antisense G1D mice replicate the human phenotype of spontaneous epilepsy associated with robust thalamocortical electrical oscillations. Additionally, and in consonance with human metabolic imaging observations, thalamus and cerebral cortex display the lowest GLUT-1 expression and glucose uptake in the mutant mouse. This depletion of brain glucose is associated with diminished plasma fatty acids and elevated ketone body levels, and with decreased brain acetyl-CoA and fatty acid contents, consistent with brain ketone body consumption and with stimulation of brain beta-oxidation and/or diminished cerebral lipid synthesis. In contrast with other epilepsies, astrocyte glutamine synthetase expression, cerebral TCA cycle intermediates, amino acid and amine neurotransmitter contents are also intact in G1D. The data suggest that the TCA cycle is preserved in G1D because reduced glycolysis and acetyl-CoA formation can be balanced by enhanced ketone body
Modeling and simulation of large scale stirred tank
NASA Astrophysics Data System (ADS)
Neuville, John R.
The purpose of this dissertation is to provide a written record of the evaluation performed on the DWPF mixing process by the construction of numerical models that resemble the geometry of this process. There were seven numerical models constructed to evaluate the DWPF mixing process and four pilot plants. The models were developed with Fluent software and the results from these models were used to evaluate the structure of the flow field and the power demand of the agitator. The results from the numerical models were compared with empirical data collected from these pilot plants that had been operated at an earlier date. Mixing is commonly used in a variety ways throughout industry to blend miscible liquids, disperse gas through liquid, form emulsions, promote heat transfer and, suspend solid particles. The DOE Sites at Hanford in Richland Washington, West Valley in New York, and Savannah River Site in Aiken South Carolina have developed a process that immobilizes highly radioactive liquid waste. The radioactive liquid waste at DWPF is an opaque sludge that is mixed in a stirred tank with glass frit particles and water to form slurry of specified proportions. The DWPF mixing process is composed of a flat bottom cylindrical mixing vessel with a centrally located helical coil, and agitator. The helical coil is used to heat and cool the contents of the tank and can improve flow circulation. The agitator shaft has two impellers; a radial blade and a hydrofoil blade. The hydrofoil is used to circulate the mixture between the top region and bottom region of the tank. The radial blade sweeps the bottom of the tank and pushes the fluid in the outward radial direction. The full scale vessel contains about 9500 gallons of slurry with flow behavior characterized as a Bingham Plastic. Particles in the mixture have an abrasive characteristic that cause excessive erosion to internal vessel components at higher impeller speeds. The desire for this mixing process is to ensure the
NASA Astrophysics Data System (ADS)
Harley, P.; Spence, S.; Early, J.; Filsinger, D.; Dietrich, M.
2013-12-01
Single-zone modelling is used to assess different collections of impeller 1D loss models. Three collections of loss models have been identified in literature, and the background to each of these collections is discussed. Each collection is evaluated using three modern automotive turbocharger style centrifugal compressors; comparisons of performance for each of the collections are made. An empirical data set taken from standard hot gas stand tests for each turbocharger is used as a baseline for comparison. Compressor range is predicted in this study; impeller diffusion ratio is shown to be a useful method of predicting compressor surge in 1D, and choke is predicted using basic compressible flow theory. The compressor designer can use this as a guide to identify the most compatible collection of losses for turbocharger compressor design applications. The analysis indicates the most appropriate collection for the design of automotive turbocharger centrifugal compressors.
Analysis of railroad tank car releases using a generalized binomial model.
Liu, Xiang; Hong, Yili
2015-11-01
The United States is experiencing an unprecedented boom in shale oil production, leading to a dramatic growth in petroleum crude oil traffic by rail. In 2014, U.S. railroads carried over 500,000 tank carloads of petroleum crude oil, up from 9500 in 2008 (a 5300% increase). In light of continual growth in crude oil by rail, there is an urgent national need to manage this emerging risk. This need has been underscored in the wake of several recent crude oil release incidents. In contrast to highway transport, which usually involves a tank trailer, a crude oil train can carry a large number of tank cars, having the potential for a large, multiple-tank-car release incident. Previous studies exclusively assumed that railroad tank car releases in the same train accident are mutually independent, thereby estimating the number of tank cars releasing given the total number of tank cars derailed based on a binomial model. This paper specifically accounts for dependent tank car releases within a train accident. We estimate the number of tank cars releasing given the number of tank cars derailed based on a generalized binomial model. The generalized binomial model provides a significantly better description for the empirical tank car accident data through our numerical case study. This research aims to provide a new methodology and new insights regarding the further development of risk management strategies for improving railroad crude oil transportation safety.
Computational Model of the Chilldown and Propellant Loading of the Space Shuttle External Tank
NASA Technical Reports Server (NTRS)
LeClair, Andre C.; Majumdar, Alok K.
2010-01-01
This paper describes a computational model of the chilldown and propellant loading of the Space Shuttle External Tank liquid oxygen and hydrogen tanks at Launch Complex 39B at Kennedy Space Center. The purpose of the computational model is to predict the time required to chilldown the entire assembly consisting of the ground system transfer line and propellant tanks in order to compare with observed loading times, to evaluate the feasibility of similar models developed for the Ares I Upper Stage. The model also predicts the history of inflow and outflow from the tank, pressure and temperature inside the tank, and heat leak through the walls. The Generalized Fluid System Simulation Program (GFSSP), a general purpose network flow analysis code, has been used to develop this computational model. The paper describes the simulation of the loading process for both tanks and compares the resulting predictions to measurements
Seismo-acoustic ray model benchmarking against experimental tank data.
Camargo Rodríguez, Orlando; Collis, Jon M; Simpson, Harry J; Ey, Emanuel; Schneiderwind, Joseph; Felisberto, Paulo
2012-08-01
Acoustic predictions of the recently developed traceo ray model, which accounts for bottom shear properties, are benchmarked against tank experimental data from the EPEE-1 and EPEE-2 (Elastic Parabolic Equation Experiment) experiments. Both experiments are representative of signal propagation in a Pekeris-like shallow-water waveguide over a non-flat isotropic elastic bottom, where significant interaction of the signal with the bottom can be expected. The benchmarks show, in particular, that the ray model can be as accurate as a parabolic approximation model benchmarked in similar conditions. The results of benchmarking are important, on one side, as a preliminary experimental validation of the model and, on the other side, demonstrates the reliability of the ray approach for seismo-acoustic applications.
A 1D model for tides waves and fine sediment in short tidal basins—Application to the Wadden Sea
NASA Astrophysics Data System (ADS)
van Prooijen, Bram Christiaan; Wang, Zheng Bing
2013-12-01
In order to simulate the dynamics of fine sediments in short tidal basins, like the Wadden Sea basins, a 1D cross-sectional averaged model is constructed to simulate tidal flow, depth-limited waves, and fine sediment transport. The key for this 1D model lies in the definition of the geometry (width and depth as function of the streamwise coordinate). The geometry is computed by implementing the water level and flow data, from a 2D flow simulation, and the hypsometric curve in the continuity equation. By means of a finite volume method, the shallow-water equations and sediment transport equations are solved. The bed shear stress consists of the sum of shear stresses by waves and flow, in which the waves are computed with a depth-limited growth equation for wave height and wave frequency. A new formulation for erosion of fines from a sandy bed is proposed in the transport equation for fine sediment. It is shown by comparison with 2D simulations and field measurements that a 1D schematization gives a proper representation of the dynamics in short tidal basins.
Dynamic one-dimensional modeling of secondary settling tanks and design impacts of sizing decisions.
Li, Ben; Stenstrom, Michael K
2014-03-01
As one of the most significant components in the activated sludge process (ASP), secondary settling tanks (SSTs) can be investigated with mathematical models to optimize design and operation. This paper takes a new look at the one-dimensional (1-D) SST model by analyzing and considering the impacts of numerical problems, especially the process robustness. An improved SST model with Yee-Roe-Davis technique as the PDE solver is proposed and compared with the widely used Takács model to show its improvement in numerical solution quality. The improved and Takács models are coupled with a bioreactor model to reevaluate ASP design basis and several popular control strategies for economic plausibility, contaminant removal efficiency and system robustness. The time-to-failure due to rising sludge blanket during overloading, as a key robustness indicator, is analyzed to demonstrate the differences caused by numerical issues in SST models. The calculated results indicate that the Takács model significantly underestimates time to failure, thus leading to a conservative design.
Modeling the performance of coated LPG tanks engulfed in fires.
Landucci, Gabriele; Molag, Menso; Cozzani, Valerio
2009-12-15
The improvement of passive fire protection of storage vessels is a key factor to enhance safety among the LPG distribution chain. A thermal and mechanical model based on finite elements simulations was developed to assess the behaviour of full size tanks used for LPG storage and transportation in fire engulfment scenarios. The model was validated by experimental results. A specific analysis of the performance of four different reference coating materials was then carried out, also defining specific key performance indicators (KPIs) to assess design safety margins in near-miss simulations. The results confirmed the wide influence of coating application on the expected vessel time to failure due to fire engulfment. A quite different performance of the alternative coating materials was evidenced. General correlations were developed among the vessel time to failure and the effective coating thickness in full engulfment scenarios, providing a preliminary assessment of the coating thickness required to prevent tank rupture for a given time lapse. The KPIs defined allowed the assessment of the available safety margins in the reference scenarios analyzed and of the robustness of thermal protection design.
Mechanistic modeling of destratification in cryogenic storage tanks using ultrasonics.
Jagannathan, T K; Mohanan, Srijith; Nagarajan, R
2014-01-01
Stratification is one of the main causes for vaporization of cryogens and increase of tank pressure during cryogenic storage. This leads subsequent problems such as cavitation in cryo-pumps, reduced length of storage time. Hence, it is vital to prevent stratification to improve the cost efficiency of storage systems. If stratified layers exist inside the tank, they have to be removed by suitable methods without venting the vapor. Sonication is one such method capable of keeping fluid layers mixed. In the present work, a mechanistic model for ultrasonic destratification is proposed and validated with destratification experiments done in water. Then, the same model is used to predict the destratification characteristics of cryogenic liquids such as liquid nitrogen (LN₂), liquid hydrogen (LH₂) and liquid ammonia (LNH₃). The destratification parameters are analysed for different frequencies of ultrasound and storage pressures by considering continuous and pulsed modes of ultrasonic operation. From the results, it is determined that use of high frequency ultrasound (low-power/continuous; high-power/pulsing) or low frequency ultrasound (continuous operation with moderate power) can both be effective in removing stratification.
Numerical Modeling of Propellant Boil-Off in a Cryogenic Storage Tank
NASA Astrophysics Data System (ADS)
Majumdar, A. K.; Steadman, T. E.; Maroney, J. L.; Sass, J. P.; Fesmire, J. E.
2008-03-01
A numerical model to predict boil-off of stored propellant in large spherical cryogenic tanks has been developed. Accurate prediction of tank boil-off rates for different thermal insulation systems was the goal of this collaborative effort. The Generalized Fluid System Simulation Program, which integrates flow analysis and conjugate heat transfer for solving complex fluid system problems, was used to create the model. Calculation of tank boil-off rate requires simultaneous simulation of heat transfer processes among liquid propellant, vapor ullage space, and tank structure. The reference tank for the boil-off model was the 850,000 gallon liquid hydrogen tank at Launch Complex 39B (LC-39B) at Kennedy Space Center, which is under study for future infrastructure improvements to support the Constellation program. The methodology employed in the numerical model was validated using a sub-scale model and tank. Experimental test data from a 1/15th scale version of the LC-39B tank using both liquid hydrogen and liquid nitrogen were used to anchor the analytical predictions of the sub-scale model. Favorable correlations between sub-scale model and experimental test data have provided confidence in full-scale tank boil-off predictions. These methods are now being used in the preliminary design for other cases including future launch vehicles.
ADMP Mixing of Tank 18F: History, Modeling, Testing, and Results
LEISHEAR, ROBERTA
2004-03-29
Residual radioactive waste was removed from Tank 18F in the F-Area Tank Farm at Savannah River Site (SRS), using the advanced design mixer pump (ADMP). Known as a slurry pump, the ADMP is a 55 foot long pump with an upper motor mounted to a steel super structure, which spans the top of the waste tank. The motor is connected by a long vertical drive shaft to a centrifugal pump, which is submerged in waste near the tank bottom. The pump mixes, or slurries, the waste within the tank so that it may be transferred out of the tank. Tank 18F is a 1.3 million gallon, 85 foot diameter underground waste storage tank, which has no internal components such as cooling coils or structural supports. The tank contained a residual 47,000 gallons of nuclear waste, consisting of a gelatinous radioactive waste known as sludge and particulate zeolite. The prediction of the ADMP success was based on nearly twenty five years of research and the application of that research to slurry pump technology. Many personnel at SRS and Pacific Northwest National Laboratories (PNNL) have significantly contributed to these efforts. This report summarizes that research which is pertinent to the ADMP performance in Tank 18F. In particular, a computational fluid dynamics (CFD) model was applied to predict the performance of the ADMP in Tank 18F.
NASA Astrophysics Data System (ADS)
Fauchez, Thomas; Davis, Anthony B.; Cornet, Céline; Szczap, Fredéric; Platnick, Steven; Dubuisson, Philippe; Thieuleux, François
2017-01-01
We investigate the impact of cirrus cloud heterogeneity on the direct emission by cloud or surface and on the scattering by ice particles in the thermal infrared (TIR). Realistic 3-D cirri are modeled with the 3DCLOUD code, and top-of-atmosphere radiances are simulated by the 3-D Monte Carlo radiative transfer (RT) algorithm 3DMCPOL for two (8.65 μm and 12.05 μm) channels of the Imaging Infrared Radiometer on CALIPSO. At nadir, comparisons of 1-D and 3-D RT show that 3-D radiances are larger than their 1-D counterparts for direct emission but smaller for scattered radiation. For our cirrus cases, 99% of the 3-D total radiance is computed by the third scattering order, which corresponds to 90% of the total computational effort, but larger optical thicknesses need more scattering orders. To radically accelerate the 3-D RT computations (using only few percent of 3-D RT time with a Monte Carlo code), even in the presence of large optical depths, we develop a hybrid model based on exact 3-D direct emission, the first scattering order from 1-D in each homogenized column, and an empirical adjustment linearly dependent on the optical thickness to account for higher scattering orders. Good agreement is found between the hybrid model and the exact 3-D radiances for two very different cirrus models without changing the empirical parameters. We anticipate that a future deterministic implementation of the hybrid model will be fast enough to process multiangle thermal imagery in a practical tomographic reconstruction of 3-D cirrus fields.
NASA Technical Reports Server (NTRS)
Fauchez, Thomas; Davis, Anthony B.; Cornet, Celine; Szczap, Frederic; Platnick, Steven; Dubuisson, Philippe; Thieuleux, Francois
2017-01-01
We investigate the impact of cirrus cloud heterogeneity on the direct emission by cloud or surface and on the scattering by ice particles in the thermal infrared (TIR). Realistic 3-D cirri are modeled with the 3DCLOUD code, and top-of-atmosphere radiances are simulated by the 3-D Monte Carlo radiative transfer (RT) algorithm 3DMCPOL for two (8.65 micrometers and 12.05 micrometers) channels of the Imaging Infrared Radiometer on CALIPSO. At nadir, comparisons of 1-D and 3-D RT show that 3-D radiances are larger than their 1-D counterparts for direct emission but smaller for scattered radiation. For our cirrus cases, 99% of the 3-D total radiance is computed by the third scattering order, which corresponds to 90% of the total computational effort, but larger optical thicknesses need more scattering orders. To radically accelerate the 3-D RT computations (using only few percent of 3-D RT time with a Monte Carlo code), even in the presence of large optical depths, we develop a hybrid model based on exact 3-D direct emission, the first scattering order from 1-D in each homogenized column, and an empirical adjustment linearly dependent on the optical thickness to account for higher scattering orders. Good agreement is found between the hybrid model and the exact 3-D radiances for two very different cirrus models without changing the empirical parameters. We anticipate that a future deterministic implementation of the hybrid model will be fast enough to process multiangle thermal imagery in a practical tomographic reconstruction of 3-D cirrus fields.
NASA Astrophysics Data System (ADS)
Le Roux, Olivier; Cornou, Cécile; Jongmans, Denis; Schwartz, Stéphane
2012-09-01
H/V spectral ratios are regularly used for estimating the bedrock depth in 1-D like basins exhibiting smooth lateral variations. In the case of 2-D or 3-D pronounced geometries, observational and numerical studies have shown that H/V curves exhibit peculiar shapes and that the H/V frequency generally overestimates 1-D theoretical resonance frequency. To investigate the capabilities of the H/V method in complex structures, a detailed comparison between measured and 3-D-simulated ambient vibrations was performed in the small-size lower Romanche valley (French Alps), which shows significant variations in geometry, downstream and upstream the Séchilienne basin. Analysing the H/V curve characteristics, two different wave propagation modes were identified along the valley. Relying on previous geophysical investigation, a power-law relationship was derived between the bedrock depth and the H/V peak frequency, which was used for building a 3-D model of the valley geometry. Simulated and experimental H/V curves were found to exhibit quite similar features in terms of curve shape and peak frequency values, validating the 3-D structure. This good agreement also evidenced two different propagation modes in the valley: 2-D resonance in the Séchilienne basin and 1-D resonance in the external parts. This study underlines the interest of H/V curves for investigating complex basin structures.
A 1-D model of the nonlinear dynamics of the human lumbar intervertebral disc
NASA Astrophysics Data System (ADS)
Marini, Giacomo; Huber, Gerd; Püschel, Klaus; Ferguson, Stephen J.
2017-01-01
Lumped parameter models of the spine have been developed to investigate its response to whole body vibration. However, these models assume the behaviour of the intervertebral disc to be linear-elastic. Recently, the authors have reported on the nonlinear dynamic behaviour of the human lumbar intervertebral disc. This response was shown to be dependent on the applied preload and amplitude of the stimuli. However, the mechanical properties of a standard linear elastic model are not dependent on the current deformation state of the system. The aim of this study was therefore to develop a model that is able to describe the axial, nonlinear quasi-static response and to predict the nonlinear dynamic characteristics of the disc. The ability to adapt the model to an individual disc's response was a specific focus of the study, with model validation performed against prior experimental data. The influence of the numerical parameters used in the simulations was investigated. The developed model exhibited an axial quasi-static and dynamic response, which agreed well with the corresponding experiments. However, the model needs further improvement to capture additional peculiar characteristics of the system dynamics, such as the change of mean point of oscillation exhibited by the specimens when oscillating in the region of nonlinear resonance. Reference time steps were identified for specific integration scheme. The study has demonstrated that taking into account the nonlinear-elastic behaviour typical of the intervertebral disc results in a predicted system oscillation much closer to the physiological response than that provided by linear-elastic models. For dynamic analysis, the use of standard linear-elastic models should be avoided, or restricted to study cases where the amplitude of the stimuli is relatively small.
Space-based observational constraints for 1-D fire smoke plume-rise models
NASA Astrophysics Data System (ADS)
Val Martin, Maria; Kahn, Ralph A.; Logan, Jennifer A.; Paugam, Ronan; Wooster, Martin; Ichoku, Charles
2012-11-01
We use a plume height climatology derived from space-based Multiangle Imaging Spectroradiometer (MISR) observations to evaluate the performance of a widely used plume-rise model. We initialize the model with assimilated meteorological fields from the NASA Goddard Earth Observing System and estimated fuel moisture content at the location and time of the MISR measurements. Fire properties that drive the plume-rise model are difficult to constrain, and we test the model with four estimates each of active fire area and total heat flux, obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) thermal anomalies available for each MISR plume and other empirical data. We demonstrate the degree to which the fire dynamical heat flux (related to active fire area and sensible heat flux) and atmospheric stability structure influence plume rise, although entrainment and possibly other less well constrained factors are also likely to be significant. Using atmospheric stability conditions, MODIS FRP, and MISR plume heights, we find that smoke plumes reaching high altitudes are characterized by higher FRP and weaker atmospheric stability conditions than those at low altitude, which tend to remain confined below the boundary layer, consistent with earlier results. However, over the diversity of conditions studied, the model simulations generally underestimate the plume height dynamic range observed by MISR and do not reliably identify plumes injected into the free troposphere, key information needed for atmospheric models to simulate smoke dispersion. We conclude that embedding in large-scale atmospheric studies an advanced plume-rise model using currently available fire constraints remains a difficult proposition, and we propose a simplified model that crudely constrains plume injection height based on two main physical factors for which some observational constraints often exist. Field experiments aimed at directly measuring fire and smoke
NASA Astrophysics Data System (ADS)
Hooshyar, M.; Hagen, S. C.; Wang, D.
2014-12-01
Hydrodynamic models are widely applied to coastal areas in order to predict water levels and flood inundation and typically involve solving a form of the Shallow Water Equations (SWE). The SWE are routinely discretized by applying numerical methods, such as the finite element method. Like other numerical models, hydrodynamic models include uncertainty. Uncertainties are generated due to errors in the discrete approximation of coastal geometry, bathymetry, bottom friction and forcing functions such as tides and wind fields. Methods to counteract these uncertainties should always begin with improvements to physical characterization of: the geometric description through increased resolution, parameters that describe land cover variations in the natural and urban environment, parameters that enhance transfer of surface forcings to the water surface, open boundary forcings, and the wetting/drying brought upon by flood and ebb cycles. When the best possible physical representation is achieved, we are left with calibration and data assimilation to reduce model uncertainty. Data assimilation has been applied to coastal hydrodynamic models to better estimate system states and/or system parameters by incorporating observed data into the model. Kalman Filter is one of the most studied data assimilation methods that minimizes the mean square errors between model state estimations and the observed data in linear systems (Kalman , 1960). For nonlinear systems, as with hydrodynamic models, a variation of Kalman filter called Ensemble Kalman Filter (EnKF), is applied to update the system state according to error statistics in the context of Monte Carlo simulations (Evensen , 2003) & (Hitoshi et. al, 2014). In this research, Kalman Filter is incorporated to simultaneously estimate an influential parameter used in the shallow water equations, bottom roughness, and to adjust the physical feature of bathymetry. Starting from an initial estimate of bottom roughness and bathymetry, and
Running scenarios using the Waste Tank Safety and Operations Hanford Site model
Stahlman, E.J.
1995-11-01
Management of the Waste Tank Safety and Operations (WTS&O) at Hanford is a large and complex task encompassing 177 tanks and having a budget of over $500 million per year. To assist managers in this task, a model based on system dynamics was developed by the Massachusetts Institute of Technology. The model simulates the WTS&O at the Hanford Tank Farms by modeling the planning, control, and flow of work conducted by Managers, Engineers, and Crafts. The model is described in Policy Analysis of Hanford Tank Farm Operations with System Dynamics Approach (Kwak 1995b) and Management Simulator for Hanford Tank Farm Operations (Kwak 1995a). This document provides guidance for users of the model in developing, running, and analyzing results of management scenarios. The reader is assumed to have an understanding of the model and its operation. Important parameters and variables in the model are described, and two scenarios are formulated as examples.
Space-based Observational Constraints for 1-D Plume Rise Models
NASA Technical Reports Server (NTRS)
Martin, Maria Val; Kahn, Ralph A.; Logan, Jennifer A.; Paguam, Ronan; Wooster, Martin; Ichoku, Charles
2012-01-01
We use a space-based plume height climatology derived from observations made by the Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the NASA Terra satellite to evaluate the ability of a plume-rise model currently embedded in several atmospheric chemical transport models (CTMs) to produce accurate smoke injection heights. We initialize the plume-rise model with assimilated meteorological fields from the NASA Goddard Earth Observing System and estimated fuel moisture content at the location and time of the MISR measurements. Fire properties that drive the plume-rise model are difficult to estimate and we test the model with four estimates for active fire area and four for total heat flux, obtained using empirical data and Moderate Resolution Imaging Spectroradiometer (MODIS) re radiative power (FRP) thermal anomalies available for each MISR plume. We show that the model is not able to reproduce the plume heights observed by MISR over the range of conditions studied (maximum r2 obtained in all configurations is 0.3). The model also fails to determine which plumes are in the free troposphere (according to MISR), key information needed for atmospheric models to simulate properly smoke dispersion. We conclude that embedding a plume-rise model using currently available re constraints in large-scale atmospheric studies remains a difficult proposition. However, we demonstrate the degree to which the fire dynamical heat flux (related to active fire area and sensible heat flux), and atmospheric stability structure influence plume rise, although other factors less well constrained (e.g., entrainment) may also be significant. Using atmospheric stability conditions, MODIS FRP, and MISR plume heights, we offer some constraints on the main physical factors that drive smoke plume rise. We find that smoke plumes reaching high altitudes are characterized by higher FRP and weaker atmospheric stability conditions than those at low altitude, which tend to remain confined
NASA Astrophysics Data System (ADS)
Alligné, S.; Decaix, J.; Müller, A.; Nicolet, C.; Avellan, F.; Münch, C.
2016-11-01
Due to the massive penetration of alternative renewable energies, hydropower is a key energy conversion technology for stabilizing the electrical power network by using hydraulic machines at off design operating conditions. At full load, the axisymmetric cavitation vortex rope developing in Francis turbines acts as an internal source of energy, leading to an instability commonly referred to as selfexcited surge. 1-D models are developed to predict this phenomenon and to define the range of safe operating points for a hydropower plant. These models involve several parameters that have to be calibrated using experimental and numerical data. The present work aims to identify these parameters with URANS computations with a particular focus on the fluid damping rising when the cavitation volume oscillates. Two test cases have been investigated: a cavitation flow in a Venturi geometry without inlet swirl and a reduced scale model of a Francis turbine operating at full load conditions. The cavitation volume oscillation is forced by imposing an unsteady outlet pressure conditions. By varying the frequency of the outlet pressure, the resonance frequency is determined. Then, the pressure amplitude and the resonance frequency are used as two objectives functions for the optimization process aiming to derive the 1-D model parameters.
NASA Astrophysics Data System (ADS)
Zhang, Lianxin; Zhang, Xuefeng; Han, Guijun; Wu, Xinrong; Cui, Xiaojian; Shao, Caixia; Sun, Chunjian; Zhang, Xiaoshuang; Wang, Xidong; Fu, Hongli
2015-09-01
At the interface between the lower atmosphere and sea surface, sea spray might significantly influence air-sea heat fluxes and subsequently, modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model, to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area, for the cases of two real typhoons from 2006, Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory (KEO), and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without, and that sea spray can enhance the heat fluxes (especially latent heat flux) considerably during a typhoon passage. Consequently, the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally, results from the simulation of the passage of typhoon Soulik (that passed KEO quickly), which included the sea spray effect, were better than for the simulated passage of typhoon Yagi (that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.
Radon exhalation from uranium mill tailings: experimental validation of a 1-D model.
Ferry, C; Richon, P; Beneito, A; Robé, M C
2001-01-01
TRACI, a model based on the physical mechanisms governing the migration of radon in unsaturated soils, has been developed to evaluate the radon flux density at the surface of uranium mill tailings. To check the validity of the TRACI model and the effectiveness of cover layers, an in situ study was launched in 1997 with the French uranium mining company, COGEMA. The study consisted of continuous measurements of moisture content, suction, radon concentration at various depths inside a UMT cover, and flux density at its surface. An initial analysis has shown that radon concentration and flux density, as calculated with a steady-state diffusion model using monthly averaged moisture contents, are in good agreement with measured monthly averaged concentrations and flux densities.
SAMPLE AOR CALCULATION USING ANSYS PARAMETRIC MODEL FOR TANK SST-AY
JULYK, L.J.; MACKEY, T.C.
2003-06-19
This document documents the ANSYS parametric model for double-shell tank AY and provides sample calculation for analysis-of-record mechanical load conditions. The purpose of this calculation is to provide a sample analysis of the DST-AY tanks based on AOR loads, plus loads identified in the Statement of Work (SOW) for CHG contract 92879. This is not an analysis. Instead, the present calculation utilizes the parametric model generated for the double shell tank DST-AY, which is based on Buyer-supplied as-built drawings and information for the analyses of record (AOR) for Double-Shell Tanks (DSTs), encompassing the existing tank load conditions, and evaluates stresses and deformations throughout the tank and surrounding soil mass.
Drawdown of floating solids in stirred tanks: scale-up study using CFD modeling.
Waghmare, Yogesh; Falk, Rick; Graham, Lisa; Koganti, Venkat
2011-10-14
This work shows development of a scale up correlation using computational fluid dynamic (CFD) simulations for floating solids drawdown operation in stirred tanks. Discrete phase modeling (DPM) simulations were used in conjunction with the lab scale experimental measurements to develop a semi-empirical correlation for the prediction of rate of drawdown of floating solid particles. The rate was correlated to average liquid velocity at the free liquid surface. Since, this correlation is based on a fundamental hydrodynamic parameter, velocity, rather than an operating parameters such as the impeller speed, it can be used for a variety of impeller types and tank geometries. The correlation was developed based on the data obtained from the 2L tank using four different tank designs and was validated against the data obtained from the 10L scale tank. The correlation was further extended to the pilot and the commercial scale tanks ranging from 40L to 4000L scale based solely on the CFD model.
2D MHD AND 1D HD MODELS OF A SOLAR FLARE—A COMPREHENSIVE COMPARISON OF THE RESULTS
Falewicz, R.; Rudawy, P.; Murawski, K.; Srivastava, A. K. E-mail: rudawy@astro.uni.wroc.pl E-mail: asrivastava.app@iitbhu.ac.in
2015-11-01
Without any doubt, solar flaring loops possess a multithread internal structure that is poorly resolved, and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modeling of flaring loops, such as selection of a structure and a number of threads, and an implementation of a proper model of the energy deposition process. A set of one-dimensional (1D) hydrodynamic and two-dimensional (2D) magnetohydrodynamic models of a flaring loop are developed to compare energy redistribution and plasma dynamics in the course of a prototypical solar flare. Basic parameters of the modeled loop are set according to the progenitor M1.8 flare recorded in AR 10126 on 2002 September 20 between 09:21 UT and 09:50 UT. The nonideal 1D models include thermal conduction and radiative losses of the optically thin plasma as energy-loss mechanisms, while the nonideal 2D models take into account viscosity and thermal conduction as energy-loss mechanisms only. The 2D models have a continuous distribution of the parameters of the plasma across the loop and are powered by varying in time and space along and across the loop heating flux. We show that such 2D models are an extreme borderline case of a multithread internal structure of the flaring loop, with a filling factor equal to 1. Nevertheless, these simple models ensure the general correctness of the obtained results and can be adopted as a correct approximation of the real flaring structures.
NASA Astrophysics Data System (ADS)
Kim, Seongryong; Rhie, Junkee; Kim, Geunyoung
2011-04-01
We propose a full-grid search procedure for broad-band waveform modelling to determine a 1-D crustal velocity model. The velocity model can be more constrained because of the use of broad-band waveforms instead of traveltimes for the crustal phases, although only a small number of event-station pairs were employed. Despite the time-consuming nature of the full-grid search method to search the whole model parameter space, the use of an empirical relationship between the P- and S-wave velocities can significantly reduce computation time. The proposed method was applied to a case in the southern Korean Peninsula. Broad-band waveforms obtained from two inland earthquakes that occurred on 2007 January 20 (Mw 4.6) and 2004 April 26 (Mw 3.6) were used to test the method. The three-layers over half-space crustal velocity model of the P- and S-wave velocities was estimated. Comparisons of waveform fitness between the final model and previously published models demonstrate advancements in the average value of waveform fitness for the inland earthquakes. In addition, 1-D velocity models were determined for three distinct tectonic regions, namely, the Gyonggi Massif, the Okcheon Belt and the Gyeongsang Basin, which are all located inside the study area. A comparison between the three models demonstrates that the crustal thickness of the southern Korean Peninsula increases from NW to SE and that the lower crustal composition of the Okcheon belt differs from that of the other tectonic regions.
Kimpara, Hideyuki; Nakahira, Yuko; Iwamoto, Masami
2016-08-01
Accurately predicting the occupant kinematics is critical to better understand the injury mechanisms during an automotive crash event. The objectives of this study were to develop and validate a finite element (FE) model of the human body integrated with an active muscle model called Total HUman Model for Safety (THUMS) version 5, which has the body size of the 50th percentile American adult male (AM50). This model is characterized by being able to generate a force owing to muscle tone and to predict the occupant response during an automotive crash event. Deformable materials were assigned to all body parts of THUMS model in order to evaluate the injury probabilities. Each muscle was modeled as a Hill-type muscle model with 800 muscle-tendon compartments of 1D truss and seatbelt elements covering whole joints in the neck, thorax, lumbar region, and upper and lower extremities. THUMS was validated against 36 series of post-mortem human surrogate (PMHS) and volunteer tests on frontal, lateral, and rear impacts. The muscle architectural and kinetic properties for the hip, knee, shoulder, and elbow joints were validated in terms of the moment arms and maximum isometric joint torques over a wide range of joint angles. The muscular moment arms and maximum joint torques estimated from THUMS occupant model with 1D muscles agreed with the experimental data for a wide range of joint angles. Therefore, this model has the potential to predict the occupant kinematics and injury outcomes considering appropriate human body motions associated with various human body postures, such as sitting or standing.
Strong decays of excited 1D charmed(-strange) mesons in the covariant oscillator quark model
NASA Astrophysics Data System (ADS)
Maeda, Tomohito; Yoshida, Kento; Yamada, Kenji; Ishida, Shin; Oda, Masuho
2016-05-01
Recently observed charmed mesons, D1* (2760), D3* (2760) and charmed-strange mesons, Ds1 * (2860), Ds3 * (2860), by BaBar and LHCb collaborations are considered to be plausible candidates for c q ¯ 13 DJ (q = u, d, s) states. We calculate the strong decays with one pion (kaon) emission of these states including well-established 1S and 1P charmed(-strange) mesons within the framework of the covariant oscillator quark model. The results obtained are compared with the experimental data and the typical nonrelativistic quark-model calculations. Concerning the results for 1S and 1P states, we find that, thanks to the relativistic effects of decay form factors, our model parameters take reasonable values, though our relativistic approach and the nonrelativistic quark model give similar decay widths in agreement with experiment. While the results obtained for 13 DJ=1,3 states are roughly consistent with the present data, they should be checked by the future precise measurement.
Modeling structures of 1D PhC for telecommunication applications
NASA Astrophysics Data System (ADS)
Zawistowski, Zygmunt J.; Jaskorzyńska, BoŻena
2016-09-01
Effective method of modeling 1-dimensional photonic crystals structures is presented. As an illustration of the method a concept of widely tunable narrow band drop filter is described. As an active electro-optic material a liquid crystal is used. Very good parameters are obtained so the presented structure is suitable for fast packet switched wavelength division multiplexing networks (WDM).
Multi-Objective Optimization of the Tank Model
NASA Astrophysics Data System (ADS)
Tanakamaru, H.
2002-12-01
The Tank Model is a conceptual rainfall-runoff model developed by Sugawara, which has 16 parameters including 4 initial storage depths. In this study, parameter optimization of the Tank Model using the multi-objectives is investigated. The root mean square error and the root mean square of relative error of simulated daily runoff hydrograph, which show obvious trade-off relationship, are adopted as objective functions and these objectives are minimized under the constraint of the permitted water balance error. The classical weighting method is applied to obtain discrete Pareto optimal solutions of the multi-objective problem. The problem is converted into a single-objective problem by the weighting method. The SCE-UA single-objective global optimization algorithm (Duan et al., 1992) is applied here for solving the problem. Such a classical method is not suited to approximate the continuous Pareto space because many times of single-objective optimization are required (i.e. a huge number of function evaluations is required) to obtain a lot of discrete Pareto solutions. To overcome the difficulties, effective and efficient new approaches such as the MOCOM-UA method (Yapo et al., 1998) have been developed. Here, a new simple approach based on the random search algorithm is developed to approximate the entire Pareto space. In this approach, a large number of new parameter sets is generated randomly in parameter ranges formed by original discrete Pareto solutions and function evaluations of generated parameter sets are conducted. After removing solutions that do not satisfy constraints, non-dominated solutions (Pareto ranking 1) are selected from generated solutions and original discrete solutions. The calibration study was done by using hydrological data of the Eigenji Dam Basin, Japan and results show that combination of the weighting method and the random search algorithm is effective and efficient to approximate the entire Pareto space of the multi-objective problem.
Reactive Transport Modeling of Microbially-Mediated Chromate Reduction in 1-D Soil Columns
NASA Astrophysics Data System (ADS)
Qiu, H.; Viamajala, S.; Alam, M. M.; Peyton, B. M.; Petersen, J. N.; Yonge, D. R.
2002-12-01
Cr(VI) reduction tests were performed with the well known metal reducing bacterium Shewanella oneidensis MR-1 in liquid phase batch reactors and continuous flow soil columns under anaerobic conditions. In the batch tests, the cultures were grown with fumarate as the terminal electron acceptor and lactate as the electron donor in a simulated groundwater medium to determine yield coefficients and specific growth rates. The bench-scale soil column experiments were carried out with MR-1 to test the hypothesis that the kinetic parameters obtained in batch studies, combined with microbial attachment /detachment processes, will accurately predict reactive transport of Cr(VI) during bacterial Cr(VI) reduction in a soil matrix. Cr(VI)-free simulated groundwater media containing fumarate as the limiting substrate and lactate was supplied to a 2.1cm (ID) x 15 cm soil column inoculated with MR-1 for a duration of 9 residence times to allow for biomass to build-up in the column. Thereafter the column was supplied with both Cr(VI) and substrate. The concentrations of effluent substrate, biomass and Cr(VI) were monitored on a periodic basis and attached biomass in the column was measured in the termination of each column test. A reactive transport model was developed in which 6 governing equations deal with Cr(VI) bioreaction, fumarate (as electron donor) consumption, aqueous biomass growth and transport, solid biomass detachment and attachment kinetics, aqueous and solid phase enzyme reaction and transport, respectively. The model incorporating the enzyme reaction kinetics for Cr(VI) reduction, Monod kinetic expressions for substrate depletion, nonlinear attachment and detachment kinetics for aqueous and solid phase microorganism concentration, was solved by a fully implicit, finite-difference procedure using RT3D (A Modular Computer Code for Reactive Multi-species Transport in 3-Dimensional Groundwater Systems) platform in one dimension. Cr(VI)-free column data was used to
REMOVAL OF TANK AND SEWER SEDIMENT BY GATE FLUSHING: COMPUTATIONAL FLUID DYNAMICS MODEL STUDIES
This presentation will discuss the application of a computational fluid dynamics 3D flow model to simulate gate flushing for removing tank/sewer sediments. The physical model of the flushing device was a tank fabricated and installed at the head-end of a hydraulic flume. The fl...
Stochastic Heat Equation Limit of a (2 + 1)d Growth Model
NASA Astrophysics Data System (ADS)
Borodin, Alexei; Corwin, Ivan; Toninelli, Fabio Lucio
2017-03-01
We determine a {q to 1} limit of the two-dimensional q-Whittaker driven particle system on the torus studied previously in Corwin and Toninelli (Electron. Commun. Probab. 21(44):1-12, 2016). This has an interpretation as a (2 + 1)-dimensional stochastic interface growth model, which is believed to belong to the so-called anisotropic Kardar-Parisi-Zhang (KPZ) class. This limit falls into a general class of two-dimensional systems of driven linear SDEs which have stationary measures on gradients. Taking the number of particles to infinity we demonstrate Gaussian free field type fluctuations for the stationary measure. Considering the temporal evolution of the stationary measure, we determine that along characteristics, correlations are asymptotically given by those of the (2 + 1)-dimensional additive stochastic heat equation. This confirms (for this model) the prediction that the non-linearity for the anisotropic KPZ equation in (2 + 1)-dimension is irrelevant.
A 1-D Model of the 4 Bed Molecular Sieve of the Carbon Dioxide Removal Assembly
NASA Technical Reports Server (NTRS)
Coker, Robert; Knox, Jim
2015-01-01
Developments to improve system efficiency and reliability for water and carbon dioxide separation systems on crewed vehicles combine sub-scale systems testing and multi-physics simulations. This paper describes the development of COMSOL simulations in support of the Life Support Systems (LSS) project within NASA's Advanced Exploration Systems (AES) program. Specifically, we model the 4 Bed Molecular Sieve (4BMS) of the Carbon Dioxide Removal Assembly (CDRA) operating on the International Space Station (ISS).
Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data
Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.
2005-06-03
CH2M HILL is producing risk/performance assessments to support the closure of single-shell tanks at the DOE's Hanford Site. As part of this effort, staff at PNNL were asked to develop release models for contaminants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. This report provides the information developed by PNNL.
Numerical Modeling of Pressurization of a Propellant Tank
NASA Technical Reports Server (NTRS)
Majumdar, Alok; Steadman, Todd
1999-01-01
An unsteady finite volume procedure has been developed to predict the history o pressure, temperature and mass flow rate of the pressurant and propellant during the expulsion of the propellant from a tan. The time dependent mass, momentum and energy conservation equations are solved at the ullage space. The model accounts for the change in the ullage volume due to expulsion of the propellant. It also accounts for the heat transfer from the tank wall and propellant to the ullage gas. The procedure was incorporated in the Generalized Fluid System Simulation Program (GFSSP). The results of several test cases were then compared with a published correlation of pressurant requirements for a given displacement of propellant. The agreement between the predictions and the correlation was found to be satisfactory.
Dynamical signature of the edge state in the 1D Aubry-André model
NASA Astrophysics Data System (ADS)
Shen, H. Z.; Yi, X. X.; Oh, C. H.
2014-04-01
Topological features have become an intensively studied subject in many fields of physics. As a witness of topological phase, the edge states are topologically protected and may be helpful in quantum information processing. In this paper, we define a measure to quantify the dynamical localization of the system and simulate the localization in the one-dimensional Aubry-André model. We find an interesting connection between the edge states and the dynamical localization of the system, this connection may be used as a signature of the edge state and topological phase.
Constraining quantum critical dynamics: (2+1)D Ising model and beyond.
Witczak-Krempa, William
2015-05-01
Quantum critical (QC) phase transitions generally lead to the absence of quasiparticles. The resulting correlated quantum fluid, when thermally excited, displays rich universal dynamics. We establish nonperturbative constraints on the linear-response dynamics of conformal QC systems at finite temperature, in spatial dimensions above 1. Specifically, we analyze the large frequency or momentum asymptotics of observables, which we use to derive powerful sum rules and inequalities. The general results are applied to the O(N) Wilson-Fisher fixed point, describing the QC Ising model when N=1. We focus on the order parameter and scalar susceptibilities, and the dynamical shear viscosity. Connections to simulations, experiments, and gauge theories are made.
1D Unsteady Flow and Sediment Transport Model for Channel Network
NASA Astrophysics Data System (ADS)
bai, Y.; Duan, J. G.
2012-12-01
This paper presents a one-dimensional unsteady flow and sediment transport model for simulating flood routing and sediment transport over mobile alluvium in channel network. The modified St. Venant equation together with the suspended sediment and bed load transport equations are solved simultaneously to obtain flow properties and sediment transport rates. The Godunov-type finite volume method is employed, and the flux terms are discretized by using the upwind and the HLLC schemes. Then, the Exner equation is used to solve for bed elevation changes. In unsteady flow, sediment transport is non-equilibrium, therefore suspended load adaptation coefficient and bed load adaptation length are used to account for the difference between equilibrium and non-equilibrium sediment transport rate. At river confluences, water surface elevations are kept the same, and the law of mass conservation is used as the internal boundary conditions. An unprecedented flood event occurred in the Santa Cruz River, Tucson, Arizona, in July 2006, is used to test the performances of the model. Simulated results of water surface elevation and bed elevation changes show good agreements with the measurements.
Modeling of the Plasma Electrode Bias in the Negative Ion Sources with 1D PIC Method
Matsushita, D.; Kuppel, S.; Hatayama, A.; Fukano, A.; Bacal, M.
2009-03-12
The effect of the plasma electrode bias voltage in the negative ion sources is modeled and investigated with one-dimensional plasma simulation. A particle-in-cell (PIC) method is applied to simulate the motion of charged particles in their self-consistent electric field. In the simulation, the electron current density is fixed to produce the bias voltage. The tendency of current-voltage characteristics obtained in the simulation show agreement with the one obtained from a simple probe theory. In addition, the H{sup -} ion density peak appears at the bias voltage close to the plasma potential as observed in the experiment. The physical mechanism of this peak H{sup -} ion density is discussed.
Hyperbolic reformulation of a 1D viscoelastic blood flow model and ADER finite volume schemes
Montecinos, Gino I.; Müller, Lucas O.; Toro, Eleuterio F.
2014-06-01
The applicability of ADER finite volume methods to solve hyperbolic balance laws with stiff source terms in the context of well-balanced and non-conservative schemes is extended to solve a one-dimensional blood flow model for viscoelastic vessels, reformulated as a hyperbolic system, via a relaxation time. A criterion for selecting relaxation times is found and an empirical convergence rate assessment is carried out to support this result. The proposed methodology is validated by applying it to a network of viscoelastic vessels for which experimental and numerical results are available. The agreement between the results obtained in the present paper and those available in the literature is satisfactory. Key features of the present formulation and numerical methodologies, such as accuracy, efficiency and robustness, are fully discussed in the paper.
Pool Formation in Boulder-Bed Streams: Implications From 1-D and 2-D Numerical Modeling
NASA Astrophysics Data System (ADS)
Harrison, L. R.; Keller, E. A.
2003-12-01
In mountain rivers of Southern California, boulder-large roughness elements strongly influence flow hydraulics and pool formation and maintenance. In these systems, boulders appear to control the stream morphology by converging flow and producing deep pools during channel forming discharges. Our research goal is to develop quantitative relationships between boulder roughness elements, temporal patterns of scour and fill, and geomorphic processes that are important in producing pool habitat. The longitudinal distribution of shear stress, unit stream power and velocity were estimated along a 48 m reach on Rattlesnake Creek, using the HEC-RAS v 3.0 and River 2-D numerical models. The reach has an average slope of 0.02 and consists of a pool-riffle sequence with a large boulder constriction directly above the pool. Model runs were performed for a range of stream discharges to test if scour and fill thresholds for pool and riffle environments could be identified. Results from the HEC-RAS simulations identified that thresholds in shear stress, unit stream power and mean velocity occur above a discharge of 5.0 cms. Results from the one-dimensional analysis suggest that the reversal in competency is likely due to changes in cross-sectional width at varying flows. River 2-D predictions indicated that strong transverse velocity gradients were present through the pool at higher modeled discharges. At a flow of 0.5 cms (roughly 1/10th bankfull discharge), velocities are estimated at 0.6 m/s and 1.3 m/s for the pool and riffle, respectively. During discharges of 5.15 cms (approximate bankfull discharge), the maximum velocity in the pool center increased to nearly 3.0 m/s, while the maximum velocity over the riffle is estimated at approximately 2.5 cms. These results are consistent with those predicted by HEC-RAS, though the reversal appears to be limited to a narrow jet that occurs through the pool head and pool center. Model predictions suggest that the velocity reversal is
Study on Effects of the Stochastic Delay Probability for 1d CA Model of Traffic Flow
NASA Astrophysics Data System (ADS)
Xue, Yu; Chen, Yan-Hong; Kong, Ling-Jiang
Considering the effects of different factors on the stochastic delay probability, the delay probability has been classified into three cases. The first case corresponding to the brake state has a large delay probability if the anticipant velocity is larger than the gap between the successive cars. The second one corresponding to the following-the-leader rule has intermediate delay probability if the anticipant velocity is equal to the gap. Finally, the third case is the acceleration, which has minimum delay probability. The fundamental diagram obtained by numerical simulation shows the different properties compared to that by the NaSch model, in which there exist two different regions, corresponding to the coexistence state, and jamming state respectively.
NASA Astrophysics Data System (ADS)
Jahromi, Amir E.; Miller, Franklin K.
2016-03-01
A sub Kelvin Active Magnetic Regenerative Refrigerator (AMRR) is being developed at the University of Wisconsin - Madison. This AMRR consists of two circulators, two regenerators, one superleak, one cold heat exchanger, and two warm heat exchangers. The circulators are novel non-moving part pumps that reciprocate a superfluid mixture of 4He-3He in the system. Heat from the mixture is removed within the two regenerators of this tandem system. An accurate model of the regenerators in this AMRR is necessary in order to predict the performance of these components, which in turn helps predicting the overall performance of the AMRR system. This work presents modeling methodology along with results from a 1-D transient numerical model of the regenerators of an AMRR capable of removing 2.5 mW at 850 mK at cyclic steady state.
Development of a 3D to 1D Particle Transport Model to Predict Deposition in the Lungs
NASA Astrophysics Data System (ADS)
Oakes, Jessica M.; Grandmont, Celine; Shadden, Shawn C.; Vignon-Clementel, Irene E.
2014-11-01
Aerosolized particles are commonly used for therapeutic drug delivery as they can be delivered to the body systemically or be used to treat lung diseases. Recent advances in computational resources have allowed for sophisticated pulmonary simulations, however it is currently impossible to solve for airflow and particle transport for all length and time scales of the lung. Instead, multi-scale methods must be used. In our recent work, where computational methods were employed to solve for airflow and particle transport in the rat airways (Oakes et al. (2014), Annals of Biomedical Engineering 42, 899), the number of particles to exit downstream of the 3D domain was determined. In this current work, the time-dependent Lagrangian description of particles was used to numerically solve a 1D convection-diffusion model (trumpet model, Taulbee and Yu (1975), Journal of Applied Physiology, 38, 77) parameterized specifically for the lung. The expansion of the airway dimensions was determined based on data collected from our aerosol exposure experiments (Oakes et al. (2014), Journal of Applied Physiology, 116, 1561). This 3D-1D framework enables us to predict the fate of particles in the whole lung. This work was supported by the Whitaker Foundation at the IIE, a INRIA Associated Team Postdoc Grant, and a UC Presidential Fellowship.
NASA Astrophysics Data System (ADS)
Hayden-Lesmeister, A.; Remo, J. W.; Piazza, B.
2015-12-01
The Atchafalaya River (AR) in Louisiana is the principal distributary of the Mississippi River (MR), and its basin contains the largest contiguous area of baldcypress-water tupelo swamp forests in North America. After designation of the Atchafalaya River Basin (ARB) as a federal floodway following the destructive 1927 MR flood, it was extensively modified to accommodate a substantial portion of the MR flow (~25%) to mitigate flooding in southern Louisiana. These modifications and increased flows resulted in substantial incision along large portions of the AR, altering connectivity between the river and its associated waterbodies. As a result of incision, the hydroperiod has been substantially altered, which has contributed to a decline in ecological health of the ARB's baldcypress-water tupelo forests. While it is recognized that the altered hydroperiod has negatively affected natural baldcypress regeneration, it is unclear whether proposed projects designed to enhance flow connectivity will increase long-term survival of these forests. In this study, we have constructed a 1D2D hydrodynamic model using SOBEK 2.12 to realistically model key physical parameters such as residence times, inundation extent, water-surface elevations (WSELs), and flow velocities to increase our understanding of the ARB's altered hydroperiod and the consequences for baldcypress-water tupelo forests. While the model encompasses a majority of the ARB, our modeling effort is focused on the Flat Lake Water Management Unit located in the southern portion of the ARB, where it will also be used to evaluate flow connectivity enhancement projects within the management unit. We believe our 1D2D hybrid hydraulic modeling approach will provide the flexibility and accuracy needed to guide connectivity enhancement efforts in the ARB and may provide a model framework for guiding similar efforts along other highly-altered river systems.
A 1D pulse wave propagation model of the hemodynamics of calf muscle pump function
Keijsers, J M T; Leguy, C A D; Huberts, W; Narracott, A J; Rittweger, J; van de Vosse, F N
2015-01-01
The calf muscle pump is a mechanism which increases venous return and thereby compensates for the fluid shift towards the lower body during standing. During a muscle contraction, the embedded deep veins collapse and venous return increases. In the subsequent relaxation phase, muscle perfusion increases due to increased perfusion pressure, as the proximal venous valves temporarily reduce the distal venous pressure (shielding). The superficial and deep veins are connected via perforators, which contain valves allowing flow in the superficial-to-deep direction. The aim of this study is to investigate and quantify the physiological mechanisms of the calf muscle pump, including the effect of venous valves, hydrostatic pressure, and the superficial venous system. Using a one-dimensional pulse wave propagation model, a muscle contraction is simulated by increasing the extravascular pressure in the deep venous segments. The hemodynamics are studied in three different configurations: a single artery–vein configuration with and without valves and a more detailed configuration including a superficial vein. Proximal venous valves increase effective venous return by 53% by preventing reflux. Furthermore, the proximal valves shielding function increases perfusion following contraction. Finally, the superficial system aids in maintaining the perfusion during the contraction phase and reduces the refilling time by 37%. © 2015 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd. PMID:25766693
MODELING DISINFECTANT RESIDUALS IN DRINKING-WATER STORAGE TANKS
The factors leading to the loss of disinfectant residual in well-mixed drinking-water storage tanks are studied. Equations relating disinfectant residual to the disinfectant's reation rate, the tank volume, and the fill and drain rates are presented. An analytical solution for ...
NASA Astrophysics Data System (ADS)
Derrida, Bernard; Hakim, Vincent
1996-12-01
We consider a simple model of domain growth: the zero-temperature 1D Ising model evolving according to the Swendsen - Wang dynamics. We find that in the long-time limit, the pair correlation function scales with a characteristic length increasing as the square of the average domain size. In that limit, a few large domains occupy almost all the space with many small domains between them. In contrast to the usual picture of coarsening, the average domain size here is not a characteristic length of the growth problem. Instead, one finds a power-law distribution for the sizes of large domains with a cut-off at a length which grows as the square of the average size of the domains.
Adhikari, K; Pal, S; Chakraborty, B; Mukherjee, S N; Gangopadhyay, A
2014-10-01
The movement of contaminants through soil imparts a variety of geo-environmental problem inclusive of lithospheric pollution. Near-surface aquifers are often vulnerable to contamination from surface source if overlying soil possesses poor resilience or contaminant attenuation capacity. The prediction of contaminant transport through soil is urged to protect groundwater from sources of pollutants. Using field simulation through column experiments and mathematical modeling like HYDRUS-1D, assessment of soil resilience and movement of contaminants through the subsurface to reach aquifers can be predicted. An outfall site of effluents of a coke oven plant comprising of alarming concentration of phenol (4-12.2 mg/L) have been considered for studying groundwater condition and quality, in situ soil characterization, and effluent characterization. Hydrogeological feature suggests the presence of near-surface aquifers at the effluent discharge site. Analysis of groundwater of nearby locality reveals the phenol concentration (0.11-0.75 mg/L) exceeded the prescribed limit of WHO specification (0.002 mg/L). The in situ soil, used in column experiment, possess higher saturated hydraulic conductivity (KS = 5.25 × 10(-4) cm/s). The soil containing 47 % silt, 11 % clay, and 1.54% organic carbon content was found to be a poor absorber of phenol (24 mg/kg). The linear phenol adsorption isotherm model showed the best fit (R(2) = 0.977, RMSE = 1.057) to the test results. Column experiments revealed that the phenol removal percent and the length of the mass transfer zone increased with increasing bed heights. The overall phenol adsorption efficiency was found to be 42-49%. Breakthrough curves (BTCs) predicted by HYDRUS-1D model appears to be close fitting with the BTCs derived from the column experiments. The phenol BTC predicted by the HYDRUS-1D model for 1.2 m depth subsurface soil, i.e., up to the depth of groundwater in the study area, showed that the exhaustion
Wave Amplitude Dependent Engineering Model of Propellant Slosh in Spherical Tanks
NASA Technical Reports Server (NTRS)
Brodnick, Jacob; Westra, Douglas G.; Eberhart, Chad J.; Yang, Hong Q.; West, Jeffrey S.
2016-01-01
Liquid propellant slosh is often a concern for the controllability of flight vehicles. Anti-slosh devices are traditionally included in propellant tank designs to limit the amount of sloshing allowed during flight. These devices and any necessary supports can be quite heavy to meet various structural requirements. Some of the burden on anti-slosh devices can be relieved by exploiting the nonlinear behavior of slosh waves in bare smooth wall tanks. A nonlinear regime slosh model for bare spherical tanks was developed through a joint analytical and experimental effort by NASA/MSFC. The developed slosh model accounts for the large damping inherent in nonlinear slosh waves which is more accurate and drives conservatism from vehicle stability analyses that use traditional bare tank slosh models. A more accurate slosh model will result in more realistic predicted slosh forces during flight reducing or removing the need for active controls during a maneuver or baffles in the tank design. Lower control gains and smaller or fewer tank baffles can reduce cost and system complexity while increasing vehicle performance. Both Computational Fluid Dynamics (CFD) simulation and slosh testing of three different spherical tank geometries were performed to develop the proposed slosh model. Several important findings were made during this effort in addition to determining the parameters to the nonlinear regime slosh model. The linear regime slosh damping trend for spherical tanks reported in NASA SP-106 was shown to be inaccurate for certain regions of a tank. Additionally, transition to the nonlinear regime for spherical tanks was only found to occur at very large wave amplitudes in the lower hemisphere and was a strong function of the propellant fill level in the upper hemisphere. The nonlinear regime damping trend was also found to be a function of the propellant fill level.
NASA Astrophysics Data System (ADS)
Viganotti, Matteo; Jackson, Ruth; Krahn, Hartmut; Dyer, Mark
2013-05-01
Earthen flood defence embankments are linear structures, raised above the flood plain, that are commonly used as flood defences in rural settings; these are often relatively old structures constructed using locally garnered material and of which little is known in terms of design and construction. Alarmingly, it is generally reported that a number of urban developments have expanded to previously rural areas; hence, acquiring knowledge about the flood defences protecting these areas has risen significantly in the agendas of basin and asset managers. This paper focusses, by reporting two case studies, on electromagnetic induction (EMI) methods that would efficiently complement routine visual inspections and would represent a first step to more detailed investigations. Evaluation of the results is presented by comparison with ERT profiles and intrusive investigation data. The EM data, acquired using a GEM-2 apparatus for frequency sounding and an EM-31 apparatus for geometrical sounding, has been handled using the prototype eGMS software tool, being developed by the eGMS international research consortium; the depth sounding data interpretation was assisted by 1D inversions obtained with the EM1DFM software developed by the University of British Columbia. Although both sounding methods showed some limitations, the models obtained were consistent with ERT models and the techniques were useful screening methods for the identification of areas of interest, such as material interfaces or potential seepage areas, within the embankment structure: 1D modelling improved the rapid assessment of earthen flood defence embankments in an estuarine environment; evidence that EMI sounding could play an important role as a monitoring tool or as a first step towards more detailed investigations.
Jensen, M D; Ingildsen, P; Rasmussen, M R; Laursen, J
2006-01-01
Aeration tank settling is a control method allowing settling in the process tank during high hydraulic load. The control method is patented. Aeration tank settling has been applied in several waste water treatment plants using the present design of the process tanks. Some process tank designs have shown to be more effective than others. To improve the design of less effective plants, computational fluid dynamics (CFD) modelling of hydraulics and sedimentation has been applied. This paper discusses the results at one particular plant experiencing problems with partly short-circuiting of the inlet and outlet causing a disruption of the sludge blanket at the outlet and thereby reducing the retention of sludge in the process tank. The model has allowed us to establish a clear picture of the problems arising at the plant during aeration tank settling. Secondly, several process tank design changes have been suggested and tested by means of computational fluid dynamics modelling. The most promising design changes have been found and reported.
NASA Astrophysics Data System (ADS)
Cheviron, Bruno; Moussa, Roger
2016-09-01
This review paper investigates the determinants of modelling choices, for numerous applications of 1-D free-surface flow and morphodynamic equations in hydrology and hydraulics, across multiple spatiotemporal scales. We aim to characterize each case study by its signature composed of model refinement (Navier-Stokes: NS; Reynolds-averaged Navier-Stokes: RANS; Saint-Venant: SV; or approximations to Saint-Venant: ASV), spatiotemporal scales and subscales (domain length: L from 1 cm to 1000 km; temporal scale: T from 1 s to 1 year; flow depth: H from 1 mm to 10 m; spatial step for modelling: δL; temporal step: δT), flow typology (Overland: O; High gradient: Hg; Bedforms: B; Fluvial: F), and dimensionless numbers (dimensionless time period T*, Reynolds number Re, Froude number Fr, slope S, inundation ratio Λz, Shields number θ). The determinants of modelling choices are therefore sought in the interplay between flow characteristics and cross-scale and scale-independent views. The influence of spatiotemporal scales on modelling choices is first quantified through the expected correlation between increasing scales and decreasing model refinements (though modelling objectives also show through the chosen spatial and temporal subscales). Then flow typology appears a secondary but important determinant in the choice of model refinement. This finding is confirmed by the discriminating values of several dimensionless numbers, which prove preferential associations between model refinements and flow typologies. This review is intended to help modellers in positioning their choices with respect to the most frequent practices, within a generic, normative procedure possibly enriched by the community for a larger, comprehensive and updated image of modelling strategies.
2D Axisymmetric vs 1D: A PIC/DSMC Model of Breakdown in Triggered Vacuum Spark Gaps
NASA Astrophysics Data System (ADS)
Moore, Stan; Moore, Chris; Boerner, Jeremiah
2015-09-01
Last year at GEC14, we presented results of one-dimensional PIC/DSMC simulations of breakdown in triggered vacuum spark gaps. In this talk, we extend the model to two-dimensional axisymmetric and compare the results to the previous 1D case. Specially, we vary the fraction of the cathode that emits electrons and neutrals (holding the total injection rates over the cathode surface constant) and show the effects of the higher dimensionality on the time to breakdown. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U. S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
NASA Astrophysics Data System (ADS)
Roundy, R. C.; Nemirovsky, D.; Kagalovsky, V.; Raikh, M. E.
2014-06-01
Motivated by recent experiments, where the tunnel magnetoresitance (TMR) of a spin valve was measured locally, we theoretically study the distribution of TMR along the surface of magnetized electrodes. We show that, even in the absence of interfacial effects (like hybridization due to donor and acceptor molecules), this distribution is very broad, and the portion of area with negative TMR is appreciable even if on average the TMR is positive. The origin of the local sign reversal is quantum interference of subsequent spin-rotation amplitudes in the course of incoherent transport of carriers between the source and the drain. We find the distribution of local TMR exactly by drawing upon formal similarity between evolution of spinors in time and of the reflection coefficient along a 1D chain in the Anderson model. The results obtained are confirmed by the numerical simulations.
Lin, Shangchao; Shih, Chih-Jen; Sresht, Vishnu; Govind Rajan, Ananth; Strano, Michael S; Blankschtein, Daniel
2016-08-03
The colloidal dispersion stability of 1D and 2D materials in the liquid phase is critical for scalable nano-manufacturing, chemical modification, composites production, and deployment as conductive inks or nanofluids. Here, we review recent computational and theoretical studies carried out by our group to model the dispersion stability of 1D and 2D materials, including single-walled carbon nanotubes, graphene, and graphene oxide in aqueous surfactant solutions or organic solvents. All-atomistic (AA) molecular dynamics (MD) simulations can probe the molecular level details of the adsorption morphology of surfactants and solvents around these materials, as well as quantify the interaction energy between the nanomaterials mediated by surfactants or solvents. Utilizing concepts from reaction kinetics and diffusion, one can directly predict the rate constants for the aggregation kinetics and dispersion life times using MD outputs. Furthermore, the use of coarse-grained (CG) MD simulations allows quantitative prediction of surfactant adsorption isotherms. Combined with the Poisson-Boltzmann equation, the Langmuir isotherm, and the DLVO theory, one can directly use CGMD outputs to: (i) predict electrostatic potentials around the nanomaterial, (ii) correlate surfactant surface coverages with surfactant concentrations in the bulk dispersion medium, and (iii) determine energy barriers against coagulation. Finally, we discuss challenges associated with studying emerging 2D materials, such as, hexagonal boron nitride (h-BN), phosphorene, and transition metal dichalcogenides (TMDCs), including molybdenum disulfide (MoS2). An outlook is provided to address these challenges with plans to develop force-field parameters for MD simulations to enable predictive modeling of emerging 2D materials in the liquid phase.
Analysis of nonlinear shallow water waves in a tank by concentrated mass model
NASA Astrophysics Data System (ADS)
Ishikawa, Satoshi; Kondou, Takahiro; Matsuzaki, Kenichiro; Yamamura, Satoshi
2016-06-01
The sloshing of liquid in a tank is an important engineering problem. For example, liquid storage tanks in industrial facilities can be damaged by earthquakes, and conversely liquid tanks, called tuned liquid damper, are often used as passive mechanical dampers. The water depth is less often than the horizontal length of the tank. In this case, shallow water wave theory can be applied, and the results indicate that the surface waveform in a shallow excited tank exhibits complex behavior caused by nonlinearity and dispersion of the liquid. This study aims to establish a practical analytical model for this phenomenon. A model is proposed that consists of masses, connecting nonlinear springs, connecting dampers, base support dampers, and base support springs. The characteristics of the connecting nonlinear springs are derived from the static and dynamic pressures. The advantages of the proposed model are that nonlinear dispersion is considered and that the problem of non-uniform water depth can be addressed. To confirm the validity of the model, numerical results obtained from the model are compared with theoretical values of the natural frequencies of rectangular and triangular tanks. Numerical results are also compared with experimental results for a rectangular tank. All computational results agree well with the theoretical and experimental results. Therefore, it is concluded that the proposed model is valid for the numerical analysis of nonlinear shallow water wave problems.
JACKSON VL
2011-08-31
The primary purpose of the tank mixing and sampling demonstration program is to mitigate the technical risks associated with the ability of the Hanford tank farm delivery and celtification systems to measure and deliver a uniformly mixed high-level waste (HLW) feed to the Waste Treatment and Immobilization Plant (WTP) Uniform feed to the WTP is a requirement of 24590-WTP-ICD-MG-01-019, ICD-19 - Interface Control Document for Waste Feed, although the exact definition of uniform is evolving in this context. Computational Fluid Dynamics (CFD) modeling has been used to assist in evaluating scaleup issues, study operational parameters, and predict mixing performance at full-scale.
Li, Ben; Stenstrom, M K
2014-11-15
Sedimentation is one of the most important processes that determine the performance of the activated sludge process (ASP), and secondary settling tanks (SSTs) have been frequently investigated with the mathematical models for design and operation optimization. Nevertheless their performance is often far from satisfactory. The starting point of this paper is a review of the development of settling theory, focusing on batch settling and the development of flux theory, since they played an important role in the early stage of SST investigation. The second part is an explicit review of the established 1-D SST models, including the relevant physical law, various settling behaviors (hindered, transient, and compression settling), the constitutive functions, and their advantages and disadvantages. The third part is a discussion of numerical techniques required to solve the governing equation, which is usually a partial differential equation. Finally, the most important modeling challenges, such as settleability description, settling behavior understanding, are presented.
Modeling and analysis of ORNL horizontal storage tank mobilization and mixing
Mahoney, L.A.; Terrones, G.; Eyler, L.L.
1994-06-01
The retrieval and treatment of radioactive sludges that are stored in tanks constitute a prevalent problem at several US Department of Energy sites. The tanks typically contain a settled sludge layer with non-Newtonian rheological characteristics covered by a layer of supernatant. The first step in retrieval is the mobilization and mixing of the supernatant and sludge in the storage tanks. Submerged jets have been proposed to achieve sludge mobilization in tanks, including the 189 m{sup 3} (50,000 gallon) Melton Valley Storage tanks (MVST) at Oak Ridge National Laboratory (ORNL) and the planned 378 m{sup 3} (100,000 gallon) tanks being designed as part of the MVST Capacity Increase Project (MVST-CIP). This report focuses on the modeling of mixing and mobilization in horizontal cylindrical tanks like those of the MVST design using submerged, recirculating liquid jets. The computer modeling of the mobilization and mixing processes uses the TEMPEST computational fluid dynamics program (Trend and Eyler 1992). The goals of the simulations are to determine under what conditions sludge mobilization using submerged liquid jets is feasible in tanks of this configuration, and to estimate mixing times required to approach homogeneity of the contents.
NASA Astrophysics Data System (ADS)
Chorowski, M.; Grabowski, M.; Jędrusyna, A.; Wach, J.
Helium inventory in high energy accelerators, tokamaks and free electron lasers may exceed tens of tons. The gaseous helium is stored in steel tanks under a pressure of about 20 bar and at environment temperature. Accidental rupture of any of the tanks filled with the gaseous helium will create a rapid energy release in form of physical blast. An estimation of pressure wave distribution following the tank rupture and potential consequences to the adjacent research infrastructure and buildings is a very important task, critical in the safety aspect of the whole cryogenic system. According to the present regulations the TNT equivalent approach is to be applied to evaluate the pressure wave following a potential gas storage tank rupture. A special test stand was designed and built in order to verify experimentally the blast effects in controlled conditions. In order to obtain such a shock wave a pressurized plastic tank was used. The tank was ruptured and the resulting pressure wave was recorded using a spatially-distributed array of pressure sensors connected to a high-speed data acquisition device. The results of the experiments and the comparison with theoretical values obtained from thermodynamic model of the blast are presented. A good agreement between the simulated and measured data was obtained. Recommendations regarding the applicability of thermodynamic model of physical blast versus TNT approach, to estimate consequences of gas storage tank rupture are formulated. The laboratory scale experimental results have been scaled to ITER pressurized helium storage tanks.
Modeling water retention of sludge simulants and actual saltcake tank wastes
Simmons, C.S.
1996-07-01
The Ferrocyanide Tanks Safety Program managed by Westinghouse hanford Company has been concerned with the potential combustion hazard of dry tank wastes containing ferrocyanide chemical in combination with nitrate salts. Pervious studies have shown that tank waste containing greater than 20 percent of weight as water could not be accidentally ignited. Moreover, a sustained combustion could not be propagated in such a wet waste even if it contained enough ferrocyanide to burn. Because moisture content is a key critical factor determining the safety of ferrocyanide-containing tank wastes, physical modeling was performed by Pacific Northwest National laboratory to evaluate the moisture-retaining behavior of typical tank wastes. The physical modeling reported here has quantified the mechanisms by which two main types of tank waste, sludge and saltcake, retain moisture in a tank profile under static conditions. Static conditions usually prevail after a tank profile has been stabilized by pumping out any excess interstitial liquid, which is not naturally retained by the waste as a result of physical forces such as capillarity.
Simulation model of stratified thermal energy storage tank using finite difference method
NASA Astrophysics Data System (ADS)
Waluyo, Joko
2016-06-01
Stratified TES tank is normally used in the cogeneration plant. The stratified TES tanks are simple, low cost, and equal or superior in thermal performance. The advantage of TES tank is that it enables shifting of energy usage from off-peak demand for on-peak demand requirement. To increase energy utilization in a stratified TES tank, it is required to build a simulation model which capable to simulate the charging phenomenon in the stratified TES tank precisely. This paper is aimed to develop a novel model in addressing the aforementioned problem. The model incorporated chiller into the charging of stratified TES tank system in a closed system. The model was developed in one-dimensional type involve with heat transfer aspect. The model covers the main factors affect to degradation of temperature distribution namely conduction through the tank wall, conduction between cool and warm water, mixing effect on the initial flow of the charging as well as heat loss to surrounding. The simulation model is developed based on finite difference method utilizing buffer concept theory and solved in explicit method. Validation of the simulation model is carried out using observed data obtained from operating stratified TES tank in cogeneration plant. The temperature distribution of the model capable of representing S-curve pattern as well as simulating decreased charging temperature after reaching full condition. The coefficient of determination values between the observed data and model obtained higher than 0.88. Meaning that the model has capability in simulating the charging phenomenon in the stratified TES tank. The model is not only capable of generating temperature distribution but also can be enhanced for representing transient condition during the charging of stratified TES tank. This successful model can be addressed for solving the limitation temperature occurs in charging of the stratified TES tank with the absorption chiller. Further, the stratified TES tank can be
NASA Astrophysics Data System (ADS)
Makhin, Volodymyr; Sotnikov, Vladimir; Bauer, Bruno; Lindemuth, Irvin; Sheehey, Peter
2001-10-01
1D modeling of the initial state of wire explosions (“cold start” with updated SESAME tables) was examined using 1D version of the Eulerian Magnetohydrodynamic Radiative Code (MHRDR). Simulations were carried out for two regimes: with (black body radiative model) and without radiative losses. Results of the simulations revealed strong dependence of the time of explosion and expansion speed of the wire on the implemented radiative model. This shows that it is necessary to accurately include radiative losses to model “cold start” wire explosions. 2D modeling of the m=0 sausage instability with sheared axial flow. The MHRDR simulations were used to obtain the growth rate of the m=0 sausage instability in plasma column with initial Bennett equilibrium profile with and without shear flow. These growth rates appeared to be in good agreement with growth rates calculated from the linearized MHD equations.
NASA Technical Reports Server (NTRS)
Majumdar, Alok K.; LeClair, Andre C.; Hedayat, Ali
2016-01-01
This paper presents a numerical model of pressurization of a cryogenic propellant tank for the Integrated Vehicle Fluid (IVF) system using the Generalized Fluid System Simulation Program (GFSSP). The IVF propulsion system, being developed by United Launch Alliance, uses boiloff propellants to drive thrusters for the reaction control system as well as to run internal combustion engines to develop power and drive compressors to pressurize propellant tanks. NASA Marshall Space Flight Center (MSFC) has been running tests to verify the functioning of the IVF system using a flight tank. GFSSP, a finite volume based flow network analysis software developed at MSFC, has been used to develop an integrated model of the tank and the pressurization system. This paper presents an iterative algorithm for converging the interface boundary conditions between different component models of a large system model. The model results have been compared with test data.
Study of the ion kinetic effects in ICF run-away burn using a quasi-1D hybrid model
NASA Astrophysics Data System (ADS)
Huang, C.-K.; Molvig, K.; Albright, B. J.; Dodd, E. S.; Vold, E. L.; Kagan, G.; Hoffman, N. M.
2017-02-01
The loss of fuel ions in the Gamow peak and other kinetic effects related to the α particles during ignition, run-away burn, and disassembly stages of an inertial confinement fusion D-T capsule are investigated with a quasi-1D hybrid volume ignition model that includes kinetic ions, fluid electrons, Planckian radiation photons, and a metallic pusher. The fuel ion loss due to the Knudsen effect at the fuel-pusher interface is accounted for by a local-loss model by Molvig et al. [Phys. Rev. Lett. 109, 095001 (2012)] with an albedo model for ions returning from the pusher wall. The tail refilling and relaxation of the fuel ion distribution are captured with a nonlinear Fokker-Planck solver. Alpha heating of the fuel ions is modeled kinetically while simple models for finite alpha range and electron heating are used. This dynamical model is benchmarked with a 3 T hydrodynamic burn model employing similar assumptions. For an energetic pusher (˜40 kJ) that compresses the fuel to an areal density of ˜1.07 g/cm 2 at ignition, the simulation shows that the Knudsen effect can substantially limit ion temperature rise in runaway burn. While the final yield decreases modestly from kinetic effects of the α particles, large reduction of the fuel reactivity during ignition and runaway burn may require a higher Knudsen loss rate compared to the rise time of the temperatures above ˜25 keV when the broad D-T Gamow peak merges into the bulk Maxwellian distribution.
Models for recurrent gas release event behavior in hazardous waste tanks
Anderson, D.N.; Arnold, B.C.
1994-08-01
Certain radioactive waste storage tanks at the United States Department of Energy Hanford facilities continuously generate gases as a result of radiolysis and chemical reactions. The congealed sludge in these tanks traps the gases and causes the level of the waste within the tanks to rise. The waste level continues to rise until the sludge becomes buoyant and ``rolls over``, changing places with heavier fluid on top. During a rollover, the trapped gases are released, resulting, in a sudden drop in the waste level. This is known as a gas release event (GRE). After a GRE, the wastes leading to another GRE. We present nonlinear time waste re-congeals and gas again accumulates leading to another GRE. We present nonlinear time series models that produce simulated sample paths that closely resemble the temporal history of waste levels in these tanks. The models also imitate the random GRE, behavior observed in the temporal waste level history of a storage tank. We are interested in using the structure of these models to understand the probabilistic behavior of the random variable ``time between consecutive GRE`s``. Understanding the stochastic nature of this random variable is important because the hydrogen and nitrous oxide gases released from a GRE, are flammable and the ammonia that is released is a health risk. From a safety perspective, activity around such waste tanks should be halted when a GRE is imminent. With credible GRE models, we can establish time windows in which waste tank research and maintenance activities can be safely performed.
NASA Astrophysics Data System (ADS)
Li, Zhanhui; Huang, Qinghua; Xie, Xingbing; Tang, Xingong; Chang, Liao
2016-08-01
We present a generic 1D forward modeling and inversion algorithm for transient electromagnetic (TEM) data with an arbitrary horizontal transmitting loop and receivers at any depth in a layered earth. Both the Hankel and sine transforms required in the forward algorithm are calculated using the filter method. The adjoint-equation method is used to derive the formulation of data sensitivity at any depth in non-permeable media. The inversion algorithm based on this forward modeling algorithm and sensitivity formulation is developed using the Gauss-Newton iteration method combined with the Tikhonov regularization. We propose a new data-weighting method to minimize the initial model dependence that enhances the convergence stability. On a laptop with a CPU of i7-5700HQ@3.5 GHz, the inversion iteration of a 200 layered input model with a single receiver takes only 0.34 s, while it increases to only 0.53 s for the data from four receivers at a same depth. For the case of four receivers at different depths, the inversion iteration runtime increases to 1.3 s. Modeling the data with an irregular loop and an equal-area square loop indicates that the effect of the loop geometry is significant at early times and vanishes gradually along the diffusion of TEM field. For a stratified earth, inversion of data from more than one receiver is useful in noise reducing to get a more credible layered earth. However, for a resistive layer shielded below a conductive layer, increasing the number of receivers on the ground does not have significant improvement in recovering the resistive layer. Even with a down-hole TEM sounding, the shielded resistive layer cannot be recovered if all receivers are above the shielded resistive layer. However, our modeling demonstrates remarkable improvement in detecting the resistive layer with receivers in or under this layer.
NASA Astrophysics Data System (ADS)
Zolfaghari, Kiana; Duguay, Claude R.; Kheyrollah Pour, Homa
2017-01-01
A global constant value of the extinction coefficient (Kd) is usually specified in lake models to parameterize water clarity. This study aimed to improve the performance of the 1-D freshwater lake (FLake) model using satellite-derived Kd for Lake Erie. The CoastColour algorithm was applied to MERIS satellite imagery to estimate Kd. The constant (0.2 m-1) and satellite-derived Kd values as well as radiation fluxes and meteorological station observations were then used to run FLake for a meteorological station on Lake Erie. Results improved compared to using the constant Kd value (0.2 m-1). No significant improvement was found in FLake-simulated lake surface water temperature (LSWT) when Kd variations in time were considered using a monthly average. Therefore, results suggest that a time-independent, lake-specific, and constant satellite-derived Kd value can reproduce LSWT with sufficient accuracy for the Lake Erie station. A sensitivity analysis was also performed to assess the impact of various Kd values on the simulation outputs. Results show that FLake is sensitive to variations in Kd to estimate the thermal structure of Lake Erie. Dark waters result in warmer spring and colder fall temperatures compared to clear waters. Dark waters always produce colder mean water column temperature (MWCT) and lake bottom water temperature (LBWT), shallower mixed layer depth (MLD), longer ice cover duration, and thicker ice. The sensitivity of FLake to Kd variations was more pronounced in the simulation of MWCT, LBWT, and MLD. The model was particularly sensitive to Kd values below 0.5 m-1. This is the first study to assess the value of integrating Kd from the satellite-based CoastColour algorithm into the FLake model. Satellite-derived Kd is found to be a useful input parameter for simulations with FLake and possibly other lake models, and it has potential for applicability to other lakes where Kd is not commonly measured.
NASA Astrophysics Data System (ADS)
Gloesener, Elodie; Karatekin, Özgür; Dehant, Véronique
2016-04-01
MSL Rover Environmental Monitoring Station (REMS) performed high-resolution measurements of temperature and relative humidity during more than one Martian year. In this work, a 1D subsurface model is used to study water vapor exchange between the atmosphere and the subsurface at Gale crater using REMS data. The thermal model used includes several layers of varying thickness with depth and properties that can be changed to correspond to those of Martian rocks at locations studied. It also includes the transport of water vapor through porous Martian regolith and the different phases considered are vapor, ice and adsorbed H2O. The total mass flux is given by the sum of diffusive and advective transport. The role of an adsorbing regolith on water transfer as well as the range of parameters with significant effect on water transport in Martian conditions are investigated. In addition, kinetics of the adsorption process is considered to examine its influence on the water vapor exchange between the subsurface and the atmosphere.
NASA Astrophysics Data System (ADS)
Pradel, J.-L.; David, C.; Quinebèche, S.; Blondel, P.
2014-05-01
Industrial scale-up (or scale down) in Compounding and Reactive Extrusion processes is one of the most critical R&D challenges. Indeed, most of High Performances Polymers are obtained within a reactive compounding involving chemistry: free radical grafting, in situ compatibilization, rheology control... but also side reactions: oxidation, branching, chain scission... As described by basic Arrhenius and kinetics laws, the competition between all chemical reactions depends on residence time distribution and temperature. Then, to ensure the best possible scale up methodology, we need tools to match thermal history of the formulation along the screws from a lab scale twin screw extruder to an industrial one. This paper proposes a comparison between standard scale-up laws and the use of Computer modeling Software such as Ludovic® applied and compared to experimental data. Scaling data from a compounding line to another one, applying general rules (for example at constant specific mechanical energy), shows differences between experimental and computed data, and error depends on the screw speed range. For more accurate prediction, 1D-Computer Modeling could be used to optimize the process conditions to ensure the best scale-up product, especially in temperature sensitive reactive extrusion processes. When the product temperature along the screws is the key, Ludovic® software could help to compute the temperature profile along the screws and extrapolate conditions, even screw profile, on industrial extruders.
COMPARISON OF EXPERIMENTAL RESULTS TO CFD MODELS FOR BLENDING IN A TANK USING DUAL OPPOSING JETS
Leishear, R.
2011-08-07
Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear, et.al. [1- 4]), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.
NASA Astrophysics Data System (ADS)
Hayek, W.; Sing, D.; Pont, F.; Asplund, M.
2012-03-01
We compare limb darkening laws derived from 3D hydrodynamical model atmospheres and 1D hydrostatic MARCS models for the host stars of two well-studied transiting exoplanet systems, the late-type dwarfs HD 209458 and HD 189733. The surface brightness distribution of the stellar disks is calculated for a wide spectral range using 3D LTE spectrum formation and opacity sampling⋆. We test our theoretical predictions using least-squares fits of model light curves to wavelength-integrated primary eclipses that were observed with the Hubble Space Telescope (HST). The limb darkening law derived from the 3D model of HD 209458 in the spectral region between 2900 Å and 5700 Å produces significantly better fits to the HST data, removing systematic residuals that were previously observed for model light curves based on 1D limb darkening predictions. This difference arises mainly from the shallower mean temperature structure of the 3D model, which is a consequence of the explicit simulation of stellar surface granulation where 1D models need to rely on simplified recipes. In the case of HD 189733, the model atmospheres produce practically equivalent limb darkening curves between 2900 Å and 5700 Å, partly due to obstruction by spectral lines, and the data are not sufficient to distinguish between the light curves. We also analyze HST observations between 5350 Å and 10 500 Å for this star; the 3D model leads to a better fit compared to 1D limb darkening predictions. The significant improvement of fit quality for the HD 209458 system demonstrates the higher degree of realism of 3D hydrodynamical models and the importance of surface granulation for the formation of the atmospheric radiation field of late-type stars. This result agrees well with recent investigations of limb darkening in the solar continuum and other observational tests of the 3D models. The case of HD 189733 is no contradiction as the model light curves are less sensitive to the temperature stratification of
NASA Astrophysics Data System (ADS)
Rodin, A. V.; Clancy, R. T.; Wilson, R. J.; Richardson, M.; Wolff, M.; Woods, S.
1997-07-01
Ground-based observations of Mars atmospheric temperatures, water, and aerosols have suggested that water ice clouds may regulate vertical distribution of dust and, hence, the global radiation balance, with strong seasonal forcing (Clancy et al., 1996). Under specific Martian conditions, condensation of atmospheric water occurs on the dust as Aitken cores, without external sources, dust is efficiently confined below the saturation level of water vapor. This in turn forces the thermal regime and the saturation conditions, particularly around the aphelion northern summer (Clancy et al., 1996). This effect is studied with two 1-D models, a time marching simulation (time step is 4 min), and reduced local steady-state model. Both models treat aerosol particle microphysics, turbulent transport and thermal enforcement interactively, including radiation transfer consistent with derived aerosol vertical and size distributions. Simulations show that in the aphelion season, when clouds are formed below or near 10 km, strong nonlinearity of cloud thermal feedback results in nonuniqueness of a steady-state solution with water vapor saturation level varying by as high as 5-7 km. Such model behavior appears related to observations of rapid variations of a global-average, lower atmosphere temperature over the planet in northern summer (Clancy, 1997). The stability of thermal equilibrium state is controlled by water vapor abundance and the strength of the dust source at the surface. Time marching simulations provide access to the dynamics of seasonal global dust storm relaxation that may play an important role in interannual climate variations on Mars. References: Clancy, R.T., A.W. Grossman, M.J. Wolff, P.B. James, Y.N. Billawala, B.J. Sandor, S.W. Lee, and D.J. Rudy. Water vapor saturation at low altitudes around Mars aphelion: A key to Mars climate? Icarus, 122, 36-62, 1996.
A 1D Model of Radial Ion Motion Interrupted by Ion–Neutral Interactions in a Cometary Coma
NASA Astrophysics Data System (ADS)
Vigren, E.; Eriksson, A. I.
2017-04-01
Because ion–neutral reaction cross sections are energy dependent, the distance from a cometary nucleus within which ions remain collisionally coupled to the neutrals is dictated not only by the comet’s activity level but also by the electromagnetic fields in the coma. Here we present a 1D model simulating the outward radial motion of water group ions with radial acceleration by an ambipolar electric field interrupted primarily by charge transfer processes with H2O. We also discuss the impact of plasma waves. For a given electric field profile, the model calculates key parameters, including the total ion density, n I , the H3O+/H2O+ number density and flux ratios, R dens and R flux, and the mean ion drift speed, < {u}I> , as a function of cometocentric distance. We focus primarily on a coma roughly resembling that of the ESA Rosetta mission target comet 67P/Churyumov–Gerasimenko near its perihelion in 2015 August. In the presence of a weak ambipolar electric field in the radial direction the model results suggest that the neutral coma is not sufficiently dense to keep the mean ion flow speed close to that of the neutrals by the spacecraft location (∼200 km from the nucleus). In addition, for electric field profiles giving n I and < {u}I> within limits constrained by measurements, the R dens values are significantly higher than values typically observed. However, when including the ion motion in large-amplitude plasma waves in the model, results more compatible with observations are obtained. We suggest that the variable and often low H3O+/H2O+ number density ratios observed may reflect nonradial ion trajectories strongly influenced by electromagnetic forces and/or plasma instabilities, with energization of the ion population by plasma waves.
Federal Register 2010, 2011, 2012, 2013, 2014
2013-12-19
...This action proposes special conditions for the Airbus Model A350-900 series airplanes. These airplanes will have a novel or unusual design feature(s) that will incorporate a nitrogen generation system (NGS) for all fuel tanks that actively reduce flammability exposure within the fuel tanks significantly below that required by the fuel tank flammability regulations. Among other benefits, the......
NASA Astrophysics Data System (ADS)
Soudah, Eduardo; Rossi, Riccardo; Idelsohn, Sergio; Oñate, Eugenio
2014-10-01
A reduced-order model for an efficient analysis of cardiovascular hemodynamics problems using multiscale approach is presented in this work. Starting from a patient-specific computational mesh obtained by medical imaging techniques, an analysis methodology based on a two-step automatic procedure is proposed. First a coupled 1D-3D Finite Element Simulation is performed and the results are used to adjust a reduced-order model of the 3D patient-specific area of interest. Then, this reduced-order model is coupled with the 1D model. In this way, three-dimensional effects are accounted for in the 1D model in a cost effective manner, allowing fast computation under different scenarios. The methodology proposed is validated using a patient-specific aortic coarctation model under rest and non-rest conditions.
Orbiter/External Tank Mate 3-D Solid Modeling
NASA Technical Reports Server (NTRS)
Godfrey, G. S.; Brandt, B.; Rorden, D.; Kapr, F.
2004-01-01
This research and development project presents an overview of the work completed while attending a summer 2004 American Society of Engineering Education/National Aeronautics and Space Administration (ASEE/NASA) Faculty Fellowship. This fellowship was completed at the Kennedy Space Center, Florida. The scope of the project was to complete parts, assemblies, and drawings that could be used by Ground Support Equipment (GSE) personnel to simulate situations and scenarios commonplace to the space shuttle Orbiter/External Tank (ET) Mate (50004). This mate takes place in the Vehicle Assembly Building (VAB). These simulations could then be used by NASA engineers as decision-making tools. During the summer of 2004, parts were created that defined the Orbiter/ET structural interfaces. Emphasis was placed upon assemblies that included the Orbiter/ET forward attachment (EO-1), aft left thrust strut (EO-2), aft right tripod support structure (EO-3), and crossbeam and aft feedline/umbilical supports. These assemblies are used to attach the Orbiter to the ET. The Orbiter/ET Mate assembly was then used to compare and analyze clearance distances using different Orbiter hang angles. It was found that a 30-minute arc angle change in Orbiter hang angle affected distance at the bipod strut to Orbiter yoke fitting 8.11 inches. A 3-D solid model library was established as a result of this project. This library contains parts, assemblies, and drawings translated into several formats. This library contains a collection of the following files: sti for sterolithography, stp for neutral file work, shrinkwrap for compression. tiff for photoshop work, jpeg for Internet use, and prt and asm for Pro/Engineer use. This library was made available to NASA engineers so that they could access its contents to make angle, load, and clearance analysis studies. These decision-making tools may be used by Pro/Engineer users and non-users.
NASA Astrophysics Data System (ADS)
Dzierzbicka-Glowacka, L.; Maciejewska, A.; Osiński, R.; Jakacki, J.; Jędrasik, J.
2009-04-01
This paper presents a one-dimensional Ecosystem Model. Mathematically, the pelagic variables in the model are described by a second-order partial differential equation of the diffusion type with biogeochemical sources and sinks. The temporal changes in the phytoplankton biomass are caused by primary production, respiration, mortality, grazing by zooplankton and sinking. The zooplankton biomass is affected by ingestion, excretion, respiration, fecal production, mortality, and carnivorous grazing. The changes in the pelagic detritus concentration are determined by input of: dead phytoplankton and zooplankton, natural mortality of predators, fecal pellets, and sinks: sedimentation, zooplankton grazing and decomposition. The nutrient concentration is caused by nutrient release, zooplankton excretion, predator excretion, detritus decomposition and benthic regeneration as sources and by nutrient uptake by phytoplankton as sinks. However, the benthic detritus is described by phytoplankton sedimentation, detritus sedimentation and remineralisation. The particulate organic carbon concentration is determined as the sum of phytoplankton, zooplankton and dead organic matter (detritus) concentrations. The 1D ecosystem model was used to simulate the seasonal dynamics of pelagic variables (phytoplankton, zooplankton, pelagic detritus and POC) in the southern Baltic Sea (Gdańsk Deep, Bornholm Deep and Gotland Deep). The calculations were made assuming: 1) increase in the water temperature in the upper layer - 0.008oC per year, 2) increase in the available light - 0.2% per year. Based on this trend, daily, monthly and seasonal and annual variability of phytoplankton, zooplankton, pelagic detritus and particulate organic carbon in different areas of the southern Baltic Sea (Gdańsk Deep, Borrnholm Deep and Gotland Deep) in the euphotic layer was calculated for the years: 2000, 2010, 2020, 2030, 2040 and 2050.
NASA Astrophysics Data System (ADS)
Grinč, Michal; Zeyen, Hermann; Bielik, Miroslav
2014-06-01
Using a very fast 1D method of integrated geophysical modelling, we calculated models of the Moho discontinuity and the lithosphere-asthenosphere boundary in the Carpathian-Pannonian Basin region and its surrounding tectonic units. This method is capable to constrain complicated lithospheric structures by using joint interpretation of different geophysical data sets (geoid and topography) at the same time. The Moho depth map shows significant crustal thickness variations. The thickest crust is found underneath the Carpathian arc and its immediate Foredeep. High values are found in the Eastern Carpathians and Vrancea area (44 km). The thickest crust modelled in the Southern Carpathians is 42 km. The Dinarides crust is characterized by thicknesses more than 40 km. In the East European Platform, crust has a thickness of about 34 km. In the Apuseni Mountains, the depth of the Moho is about 36 km. The Pannonian Basin and the Moesian Platform have thinner crust than the surrounding areas. Here the crustal thicknesses are less than 30 km on average. The thinnest crust can be found in the SE part of the Pannonian Basin near the contact with the Southern Carpathians where it is only 26 km. The thickest lithosphere is placed in the East European Platform, Eastern Carpathians and Southern Carpathians. The East European Platform lithosphere thickness is on average more than 120 km. A strip of thicker lithosphere follows the Eastern Carpathians and its Foredeep, where the values reach in average 160 km. A lithosphere thickness minimum can be observed at the southern border of the Southern Carpathians and in the SE part of the Pannonian Basin. Here, it is only 60 km. The extremely low values of lithospheric thickness in this area were not shown before. The Moesian Platform is characterized by an E-W trend of lithospheric thickness decrease. In the East, the thickness is about 110 km and in the west it is only 80 km. The Pannonian Basin lithospheric thickness ranges from 80 to
Flow and transport simulation models for prediction of chlorine contact tank flow-through curves.
Wang, Hong; Shao, Xuejun; Falconer, Roger A
2003-01-01
Turbulent flow, solute transport, and chemical and biological decay are some of the basic processes encountered in water treatment plants. This paper presents recent developments in the numerical simulation of turbulent flow and disinfection processes in disinfection contact tanks. Simulation runs have been conducted for various tank design alternatives and in different grid resolutions. The accuracy of simulated contact tank flow and the disinfection process depends largely on calculations of the hydrodynamic and solute transport characteristics in the tanks. A key factor of this is the accuracy of advection and shear stress term computations, which can be affected by the use of different hydrodynamic submodels and numerical schemes. The performance of a simulation model relies to a great extent on the right combination of such submodels and numerical schemes. In this study, a number of simulation models were tested against realistic tank configurations and measurements to evaluate the various combinations of turbulence models and difference schemes by analyzing predicted flow and solute transport patterns, as well as the corresponding flow-through curves. Models for disinfection tank simulations are recommended based on comparisons of simulation results with measurements. These models may also be applied to other water treatment processes such as wastewater treatment.
Application of tank, NAM, ARMA and neural network models to flood forecasting
NASA Astrophysics Data System (ADS)
Tingsanchali, Tawatchai; Gautam, Mahesh Raj
2000-10-01
Two lumped conceptual hydrological models, namely tank and NAM and a neural network model are applied to flood forecasting in two river basins in Thailand, the Wichianburi on the Pasak River and the Tha Wang Pha on the Nan River using the flood forecasting procedure developed in this study. The tank and NAM models were calibrated and verified and found to give similar results. The results were found to improve significantly by coupling stochastic and deterministic models (tank and NAM) for updating forecast output. The neural network (NN) model was compared with the tank and NAM models. The NN model does not require knowledge of catchment characteristics and internal hydrological processes. The training process or calibration is relatively simple and less time consuming compared with the extensive calibration effort required by the tank and NAM models. The NN model gives good forecasts based on available rainfall, evaporation and runoff data. The black-box nature of the NN model and the need for selecting parameters based on trial and error or rule-of-thumb, however, characterizes its inherent weakness. The performance of the three models was evaluated statistically.
Kroon, Wilco; Huberts, Wouter; Bosboom, Marielle; van de Vosse, Frans
2012-01-01
A computational method of reduced complexity is developed for simulating vascular hemodynamics by combination of one-dimensional (1D) wave propagation models for the blood vessels with zero-dimensional (0D) lumped models for the microcirculation. Despite the reduced dimension, current algorithms used to solve the model equations and simulate pressure and flow are rather complex, thereby limiting acceptance in the medical field. This complexity mainly arises from the methods used to combine the 1D and the 0D model equations. In this paper a numerical method is presented that no longer requires additional coupling methods and enables random combinations of 1D and 0D models using pressure as only state variable. The method is applied to a vascular tree consisting of 60 major arteries in the body and the head. Simulated results are realistic. The numerical method is stable and shows good convergence.
A predictive model for rollover in stratified LNG tanks
Heestand, J.; Meader, J.W.; Shipman, C.W.
1983-03-01
The incubation period preceding ''rollover'' within a stratified LNG tank involves intensive heat and mass transfers between layers. Numerical integration of equations describing these processes leads to predicted time-history and boil-off characteristics which are in excellent agreement with Sarsten's (1972) documentation of the LaSpezia rollover incident.
High Level Waste Tank Closure Modeling with Geographic Information Systems (GIS)
BOLLINGER, JAMES
2004-07-29
Waste removal from 49 underground storage tanks located in two tank farms involves three steps: bulk waste removal, water washing to remove residual waste, and in some cases chemical cleaning to remove additional residual waste. Not all waste can be completely removed by these processes-resulting in some residual waste loading following cleaning. Completely removing this residual waste would be prohibitively expensive; therefore, it will be stabilized by filling the tanks with grout. Acceptable residual waste loading inventories were determined using one-dimensional groundwater transport modeling to predict future human exposure based on several scenarios. These modeling results have been incorporated into a geographic information systems (GIS) application for rapid evaluation of various tank closure options.
Numerical Modeling of Mixing of Chemically Reacting, Non-Newtonian Slurry for Tank Waste Retrieval
Yuen, David A.; Onishi, Yasuo; Rustad, James R.; Michener, Thomas E.; Felmy, Andrew R.; Ten, Arkady A.; Hier, Catherine A.
2000-06-01
Many highly radioactive wastes will be retrieved by installing mixer pumps that inject high-speed jets to stir up the sludge, saltcake, and supernatant liquid in the tank, blending them into a slurry. This slurry will then be pumped out of the tank into a waste treatment facility. Our objectives are to investigate interactions-chemical reactions, waste rheology, and slurry mixing-occurring during the retrieval operation and to provide a scientific basis for the waste retrieval decision-making process. Specific objectives are to: (1) Evaluate numerical modeling of chemically active, non-Newtonian tank waste mixing, coupled with chemical reactions and realistic rheology; (2) Conduct numerical modeling analysis of local and global mixing of non-Newtonian and Newtonian slurries; and (3) Provide the bases to develop a scientifically justifiable, decision-making support tool for the tank waste retrieval operation.
Solids suspension and transfer studies in a model digester tank
Lewis, B E
1986-07-01
This report summarizes the development of a modified pachuca tank and air motivated agitator design for use in a fuel reprocessing plant. Various tank design features, operating conditions, and types of agitators were studied to determine their effects on solids suspension, level/density measurements, and slurry transfer ability. The recommended tank design is a cylindrical tank with a conic midsection leading to a 6-in.-diam critically safe cylindrical solids collection reservoir. The preferred agitator design is an intermittent air-flow gas-lift recirculator featuring three external air-supply lines. Solids suspension levels {ge}0% were attained using tungsten powder in water. A variety of level/density bubbler tube designs were tested to study the effect of the operation of the agitator on level and density readings. A simple 0.25-in. Sch 40 pipe gave readings as stable as any of the other more elaborate designs tested, with density fluctuations in the range of 0.01 to {similar_to}.04 g/mL. Level readings were generally not adversely affected by the operation of the agitator. Steam jet transfer was a very effective means of removing the <80-{mu}m-diam tungsten solids and solution from the tank. A coarse screen over the end of the jet suction line prevented large solids from plugging the jet. Dilution levels in the range of 8% to 10% were obtained for the transfer of water at ambient conditions. These dilution levels are higher than the typically observed values of 3% to 5%, probably because of the occurrence of condensate in the steam supply line and the relatively small volume of the solution transferred. 10 refs., 48 figs., 7 tabs.
NASA Technical Reports Server (NTRS)
Wilson, Jeffrey D.; Zimmerli, Gregory A.
2012-01-01
Good antenna-mode coupling is needed for determining the amount of propellant in a tank through the method of radio frequency mass gauging (RFMG). The antenna configuration and position in a tank are important factors in coupling the antenna to the natural electromagnetic modes. In this study, different monopole and dipole antenna mounting configurations and positions were modeled and responses simulated in a full-scale tank model with the transient solver of CST Microwave Studio (CST Computer Simulation Technology of America, Inc.). The study was undertaken to qualitatively understand the effect of antenna design and placement within a tank on the resulting radio frequency (RF) tank spectrum.
Mg line formation in late-type stellar atmospheres. II. Calculations in a grid of 1D models
NASA Astrophysics Data System (ADS)
Osorio, Y.; Barklem, P. S.
2016-02-01
Context. Mg is the α element of choice for Galactic population and chemical evolution studies because it is easily detectable in all late-type stars. Such studies require precise elemental abundances, and thus departures from local thermodynamic equilibrium (LTE) need to be accounted for. Aims: Our goal is to provide reliable departure coefficients and equivalent widths in non-LTE, and for reference in LTE, for diagnostic lines of Mg studied in late-type stars. These can be used, for example, to correct LTE spectra and abundances. Methods: Using the model atom built and tested in the preceding paper in this series, we performed non-LTE radiative transfer calculations in a grid of 3945 stellar 1D atmospheric models. We used a sub-grid of 86 models to explore the propagation of errors in the recent atomic collision calculations to the radiative transfer results. Results: We obtained departure coefficients for all the levels and equivalent widths (in LTE and non-LTE) for all the radiative transitions included in the "final" model atom presented in Paper I. Here we present and describe our results and show some examples of applications of the data. The errors that result from uncertainties in the collisional data are investigated and tabulated. The results for equivalent widths and departure coefficients are made freely available. Conclusions: Giants tend to have negative abundance corrections while dwarfs have positive, though small, corrections. Error analysis results show that uncertainties related to the atomic collision data are typically on the order of 0.01 dex or less, although for few stellar models in specific lines uncertainties can be as large as 0.03 dex. As these errors are less than or on the same order as typical corrections, we expect that we can use these results to extract Mg abundances from high-quality spectra more reliably than from classical LTE analysis. Full Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130
NASA Astrophysics Data System (ADS)
Manful, D. Y.; Kaule, G.; Wieprecht, S.; Rees, J.; Hu, W.
2009-12-01
Hydroelectric Power (HEP) is proving to be a good alternative to carbon based energy. In the past hydropower especially large scale hydro attracted significant criticism as a result of its impact on the environment. A new breed of hydroelectric dam is in the offing. The aim is to have as little a footprint as possible on the environment in both pre and post construction phases and thus minimize impact on biodiversity whilst producing clean renewable energy. The Bui dam is 400 MW scheme currently under development on the Black Volta River in the Bui national park in Ghana. The reservoir created by the Bui barrage is expected to impact (through inundation) the habitat of two species of hippos know to exist in the park, the Hippopotamus amphibius and the Choeropsis liberiensis. Computer-based models present a unique opportunity to assess quantitatively the impact of the new reservoir on the habitat of the target species in this case the H. amphibious. Until this undertaking, there were very few studies documenting the habitat of the H. amphibious let alone model it. The work and subsequent presentation will show the development of a habitat model for the Hippopotamus amphibius. The Habitat Information retrieval Program based on Streamflow Analysis, in short HIPStrA, is a one dimensional (1D) in-stream, spatially explicit hybrid construct that combines physico-chemical evidence and expert knowledge to forecast river habitat suitability (Hs) for the Hippopotamus amphibius. The version of the model presented is specifically developed to assess the impact of a reservoir created by a hydroelectric dam on potential dwelling areas in the Bui gorge for hippos. Accordingly, this version of HIPStrA simulates a special reservoir suitability index (Rsi), a metric that captures the”hippo friendliness” of any lake or reservoir. The impact of measured and simulated flood events as well as low flows, representing extreme events is also assessed. Recommendations are made for the
Karri, Naveen K.; Rinker, Michael W.; Johnson, Kenneth I.; Bapanapalli, Satish K.
2012-11-10
ABSTRACT Several tanks at the Hanford Site (in Washington State, USA) belong to the first generation of underground nuclear waste storage tanks known as single shell tanks (SSTs). These tanks were constructed between 1943 and 1964 and are well beyond their design life. This article discusses the structural analysis approach and modeling challenges encountered during the ongoing analysis of record (AOR) for evaluating the structural integrity of the SSTs. There are several geometrical and material nonlinearities and uncertainties to be dealt with while performing the modern finite element analysis of these tanks. The analysis takes into account the temperature history of the tanks and allowable mechanical operating loads of these tanks for proper estimation of creep strains and thermal degradation of material properties. The loads prescribed in the AOR models also include anticipated loads that these tanks may see during waste retrieval and closure. Due to uncertainty in a number of inputs to the models, sensitivity studies were conducted to address questions related to the boundary conditions to realistically or conservatively represent the influence of surrounding tanks in a tank farm, the influence of backfill excavation slope, the extent of backfill and the total extent of undisturbed soil surrounding the backfill. Because of the limited availability of data on the thermal and operating history for many of the individual tanks, some of the data was assumed or interpolated. However, the models developed for the analysis of record represent the bounding scenarios and include the loading conditions that the tanks were subjected to or anticipated. The modeling refinement techniques followed in the AOR resulted in conservative estimates for force and moment demands at various sections in the concrete tanks. This article discusses the modeling aspects related to Type-II and Type-III SSTs. The modeling techniques, methodology and evaluation criteria developed for
1D-Var multilayer assimilation of X-band SAR data into a detailed snowpack model
NASA Astrophysics Data System (ADS)
Phan, X. V.; Ferro-Famil, L.; Gay, M.; Durand, Y.; Dumont, M.; Morin, S.; Allain, S.; D'Urso, G.; Girard, A.
2014-10-01
The structure and physical properties of a snowpack and their temporal evolution may be simulated using meteorological data and a snow metamorphism model. Such an approach may meet limitations related to potential divergences and accumulated errors, to a limited spatial resolution, to wind or topography-induced local modulations of the physical properties of a snow cover, etc. Exogenous data are then required in order to constrain the simulator and improve its performance over time. Synthetic-aperture radars (SARs) and, in particular, recent sensors provide reflectivity maps of snow-covered environments with high temporal and spatial resolutions. The radiometric properties of a snowpack measured at sufficiently high carrier frequencies are known to be tightly related to some of its main physical parameters, like its depth, snow grain size and density. SAR acquisitions may then be used, together with an electromagnetic backscattering model (EBM) able to simulate the reflectivity of a snowpack from a set of physical descriptors, in order to constrain a physical snowpack model. In this study, we introduce a variational data assimilation scheme coupling TerraSAR-X radiometric data into the snowpack evolution model Crocus. The physical properties of a snowpack, such as snow density and optical diameter of each layer, are simulated by Crocus, fed by the local reanalysis of meteorological data (SAFRAN) at a French Alpine location. These snowpack properties are used as inputs of an EBM based on dense media radiative transfer (DMRT) theory, which simulates the total backscattering coefficient of a dry snow medium at X and higher frequency bands. After evaluating the sensitivity of the EBM to snowpack parameters, a 1D-Var data assimilation scheme is implemented in order to minimize the discrepancies between EBM simulations and observations obtained from TerraSAR-X acquisitions by modifying the physical parameters of the Crocus-simulated snowpack. The algorithm then re
DOUBLE SHELL TANK (DST) HYDROXIDE DEPLETION MODEL FOR CARBON DIOXIDE ABSORPTION
OGDEN DM; KIRCH NW
2007-10-31
This document generates a supernatant hydroxide ion depletion model based on mechanistic principles. The carbon dioxide absorption mechanistic model is developed in this report. The report also benchmarks the model against historical tank supernatant hydroxide data and vapor space carbon dioxide data. A comparison of the newly generated mechanistic model with previously applied empirical hydroxide depletion equations is also performed.
A marching in space and time (MAST) solver of the shallow water equations. Part I: The 1D model
NASA Astrophysics Data System (ADS)
Aricò, C.; Tucciarelli, T.
2007-05-01
A new approach is presented for the numerical solution of the complete 1D Saint-Venant equations. At each time step, the governing system of partial differential equations (PDEs) is split, using a fractional time step methodology, into a convective prediction system and a diffusive correction system. Convective prediction system is further split into a convective prediction and a convective correction system, according to a specified approximated potential. If a scalar exact potential of the flow field exists, correction vanishes and the solution of the convective correction system is the same solution of the prediction system. Both convective prediction and correction systems are shown to have at each x - t point a single characteristic line, and a corresponding eigenvalue equal to the local velocity. A marching in space and time (MAST) technique is used for the solution of the two systems. MAST solves a system of two ordinary differential equations (ODEs) in each computational cell, using for the time discretization a self-adjusting fraction of the original time step. The computational cells are ordered and solved according to the decreasing value of the potential in the convective prediction step and to the increasing value of the same potential in the convective correction step. The diffusive correction system is solved using an implicit scheme, that leads to the solution of a large linear system, with the same order of the cell number, but sparse, symmetric and well conditioned. The numerical model shows unconditional stability with regard of the Courant-Friedrichs-Levi (CFL) number, requires no special treatment of the source terms and a computational effort almost proportional to the cell number. Several tests have been carried out and results of the proposed scheme are in good agreement with analytical solutions, as well as with experimental data.
Schüssler, W; Artinger, R; Kim, J I; Bryan, N D; Griffin, D
2001-02-01
The humic colloid borne Am(III) transport was investigated in column experiments for Gorleben groundwater/sand systems. It was found that the interaction of Am with humic colloids is kinetically controlled, which strongly influences the migration behavior of Am(III). These kinetic effects have to be taken into account for transport/speciation modeling. The kinetically controlled availability model (KICAM) was developed to describe actinide sorption and transport in laboratory batch and column experiments. Application of the KICAM requires a chemical transport/speciation code, which simultaneously models both kinetically controlled processes and equilibrium reactions. Therefore, the code K1D was developed as a flexible research code that allows the inclusion of kinetic data in addition to transport features and chemical equilibrium. This paper presents the verification of K1D and its application to model column experiments investigating unimpeded humic colloid borne Am migration. Parmeters for reactive transport simulations were determined for a Gorleben groundwater system of high humic colloid concentration (GoHy 2227). A single set of parameters was used to model a series of column experiments. Model results correspond well to experimental data for the unretarded humic borne Am breakthrough.
NASA Astrophysics Data System (ADS)
Schüßler, W.; Artinger, R.; Kim, J. I.; Bryan, N. D.; Griffin, D.
2001-02-01
The humic colloid borne Am(III) transport was investigated in column experiments for Gorleben groundwater/sand systems. It was found that the interaction of Am with humic colloids is kinetically controlled, which strongly influences the migration behavior of Am(III). These kinetic effects have to be taken into account for transport/speciation modeling. The kinetically controlled availability model (KICAM) was developed to describe actinide sorption and transport in laboratory batch and column experiments. Application of the KICAM requires a chemical transport/speciation code, which simultaneously models both kinetically controlled processes and equilibrium reactions. Therefore, the code K1D was developed as a flexible research code that allows the inclusion of kinetic data in addition to transport features and chemical equilibrium. This paper presents the verification of K1D and its application to model column experiments investigating unimpeded humic colloid borne Am migration. Parameters for reactive transport simulations were determined for a Gorleben groundwater system of high humic colloid concentration (GoHy 2227). A single set of parameters was used to model a series of column experiments. Model results correspond well to experimental data for the unretarded humic borne Am breakthrough.
Developing a model for moisture in saltcake waste tanks: Progress report
Simmons, C.S.; Aimo, N.; Fayer, M.J.; White, M.D.
1997-07-01
This report describes a modeling effort to provide a computer simulation capability for estimating the distribution and movement of moisture in the saltcake-type waste contained in Hanford`s single-shell radioactive waste storage tanks. This moisture model goes beyond an earlier version because it describes water vapor movement as well as the interstitial liquid held in a saltcake waste. The work was performed by Pacific Northwest National Laboratory to assist Duke Engineering and Services Hanford with the Organic Tank Safety Program. The Organic Tank Safety Program is concerned whether saltcake waste, when stabilized by jet pumping, will retain sufficient moisture near the surface to preclude any possibility of an accidental ignition and propagation of burning. The nitrate/nitrite saltcake, which might also potentially include combustible organic chemicals might not always retain enough moisture near the surface to preclude any such accident. Draining liquid from a tank by pumping, coupled with moisture evaporating into a tank`s head space, may cause a dry waste surface that is not inherently safe. The moisture model was devised to help examine this safety question. The model accounts for water being continually cycled by evaporation into the head space and returned to the waste by condensation or partly lost through venting to the external atmosphere. Water evaporation occurs even in a closed tank, because it is driven by the transfer to the outside of the heat load generated by radioactivity within the waste. How dry a waste may become over time depends on the particular hydraulic properties of a saltcake, and the model uses those properties to describe the capillary flow of interstitial liquid as well as the water vapor flow caused by thermal differences within the porous waste.
Santos-Villalobos, Hector J; Gregor, Jens; Bingham, Philip R
2014-01-01
At the present, neutron sources cannot be fabricated small and powerful enough in order to achieve high resolution radiography while maintaining an adequate flux. One solution is to employ computational imaging techniques such as a Magnified Coded Source Imaging (CSI) system. A coded-mask is placed between the neutron source and the object. The system resolution is increased by reducing the size of the mask holes and the flux is increased by increasing the size of the coded-mask and/or the number of holes. One limitation of such system is that the resolution of current state-of-the-art scintillator-based detectors caps around 50um. To overcome this challenge, the coded-mask and object are magnified by making the distance from the coded-mask to the object much smaller than the distance from object to detector. In previous work, we have shown via synthetic experiments that our least squares method outperforms other methods in image quality and reconstruction precision because of the modeling of the CSI system components. However, the validation experiments were limited to simplistic neutron sources. In this work, we aim to model the flux distribution of a real neutron source and incorporate such a model in our least squares computational system. We provide a full description of the methodology used to characterize the neutron source and validate the method with synthetic experiments.
NASA Astrophysics Data System (ADS)
Marcq, E.
2012-01-01
In order to understand the early history of telluric interiors and atmospheres during the ocean magma stage, a coupled interior-atmosphere-escape model is being developed. This paper describes the atmospheric part and its first preliminary results. A unidimensional, radiative-convective, H2O-CO2 atmosphere is modeled following a vertical T(z) profile similar to Kasting (1988) and Abe and Matsui (1988). Opacities in the thermal IR are then computed using a k-correlated code (KSPECTRUM), tabulated continuum opacities for H2O-H2O and CO2-CO2 absorption, and water or sulphuric acid clouds in the moist convective zone (whenever present). The first results show the existence of two regimes depending on the relative value of the surface temperature Ts compared to a threshold temperature Tc depending on the total gaseous inventory. For Ts < Tc, efficient blanketing results in a cool upper atmosphere, a cloud cover, and a long lifetime for the underneath magma ocean with a net thermal IR flux between 160 and 200 Wm-2. For Ts > Tc, the blanketing is not efficient enough to prevent large radiative heat loss to space through a hot, cloudless atmosphere. Our current calculations may underestimate the thermal flux in the case of hot surfaces with little gaseous content in the atmosphere.
NASA Technical Reports Server (NTRS)
Sances, Dillon J.; Gangadharan, Sathya N.; Sudermann, James E.; Marsell, Brandon
2010-01-01
Liquid sloshing within spacecraft propellant tanks causes rapid energy dissipation at resonant modes, which can result in attitude destabilization of the vehicle. Identifying resonant slosh modes currently requires experimental testing and mechanical pendulum analogs to characterize the slosh dynamics. Computational Fluid Dynamics (CFD) techniques have recently been validated as an effective tool for simulating fuel slosh within free-surface propellant tanks. Propellant tanks often incorporate an internal flexible diaphragm to separate ullage and propellant which increases modeling complexity. A coupled fluid-structure CFD model is required to capture the damping effects of a flexible diaphragm on the propellant. ANSYS multidisciplinary engineering software employs a coupled solver for analyzing two-way Fluid Structure Interaction (FSI) cases such as the diaphragm propellant tank system. Slosh models generated by ANSYS software are validated by experimental lateral slosh test results. Accurate data correlation would produce an innovative technique for modeling fuel slosh within diaphragm tanks and provide an accurate and efficient tool for identifying resonant modes and the slosh dynamic response.
Achilleos, Annita; Neben, Cynthia L.; Merrill, Amy E.; Trainor, Paul A.
2016-01-01
Ribosome biogenesis is a global process required for growth and proliferation of all cells, yet perturbation of ribosome biogenesis during human development often leads to tissue-specific defects termed ribosomopathies. Transcription of the ribosomal RNAs (rRNAs) by RNA polymerases (Pol) I and III, is considered a rate limiting step of ribosome biogenesis and mutations in the genes coding for RNA Pol I and III subunits, POLR1C and POLR1D cause Treacher Collins syndrome, a rare congenital craniofacial disorder. Our understanding of the functions of individual RNA polymerase subunits, however, remains poor. We discovered that polr1c and polr1d are dynamically expressed during zebrafish embryonic development, particularly in craniofacial tissues. Consistent with this pattern of activity, polr1c and polr1d homozygous mutant zebrafish exhibit cartilage hypoplasia and cranioskeletal anomalies characteristic of humans with Treacher Collins syndrome. Mechanistically, we discovered that polr1c and polr1d loss-of-function results in deficient ribosome biogenesis, Tp53-dependent neuroepithelial cell death and a deficiency of migrating neural crest cells, which are the primary progenitors of the craniofacial skeleton. More importantly, we show that genetic inhibition of tp53 can suppress neuroepithelial cell death and ameliorate the skeletal anomalies in polr1c and polr1d mutants, providing a potential avenue to prevent the pathogenesis of Treacher Collins syndrome. Our work therefore has uncovered tissue-specific roles for polr1c and polr1d in rRNA transcription, ribosome biogenesis, and neural crest and craniofacial development during embryogenesis. Furthermore, we have established polr1c and polr1d mutant zebrafish as models of Treacher Collins syndrome together with a unifying mechanism underlying its pathogenesis and possible prevention. PMID:27448281
The Sustained Combat Model: Tank Wars II Programmers’ Manual
1991-11-01
Meeting scenario. MFKILL = 4 Mobility & firepower kill. MKILL = 2 Mobility only kill. NN = Maximum number of tanks playable. NULL = 0 No specific target... NULL , FLS TGT, 1 FD, HD1, FE, TURRET, HULL, BLU, RED, MEETNG, RATTAK, 2 BATTAK, ALIVE, MKILL, FKILL, MFKILL, WKILL, KKILL, 3 SLOWNG,STATNY,ACCELG,MAXVL...include ’common.h’ data color, pi, twopi, deg I /’Blue’, ’Red ’,3.141.592654, 6.283185308, 57.29577951/ data ALL, NULL , FLS TOT /0, 0, -1/ data FD, HD
NASA Astrophysics Data System (ADS)
Kirkby, A.; Heinson, G.; Holford, S.; Thiel, S.
2015-06-01
We present 1D anisotropic inversion of magnetotelluric (MT) data as a potential tool for mapping structural permeability in sedimentary basins. Using 1D inversions of a 171 site, broadband MT data set from the Koroit region of the Otway Basin, Victoria, Australia, we have delineated an electrically anisotropic layer at approximately 2.5 to 3.5 km depth. The anisotropy strike is consistent between stations at approximately 160° east of north. The depth of anisotropy corresponds to the top depth of the Lower Cretaceous Crayfish Group, and the anisotropy factor increases from west to east. We interpret the anisotropy as resulting from north-northwest oriented, fluid-filled fractures resulting in enhanced electrical and hydraulic conductivity. This interpretation is consistent with permeability data from well formation tests. It is also consistent with the orientation of mapped faults in the area, which are optimally oriented for reactivation in the current stress field.
Li, Jiajia; Deng, Baoqing; Zhang, Bing; Shen, Xiuzhong; Kim, Chang Nyung
2015-01-01
A simulation of an unbaffled stirred tank reactor driven by a magnetic stirring rod was carried out in a moving reference frame. The free surface of unbaffled stirred tank was captured by Euler-Euler model coupled with the volume of fluid (VOF) method. The re-normalization group (RNG) k-ɛ model, large eddy simulation (LES) model and detached eddy simulation (DES) model were evaluated for simulating the flow field in the stirred tank. All turbulence models can reproduce the tangential velocity in an unbaffled stirred tank with a rotational speed of 150 rpm, 250 rpm and 400 rpm, respectively. Radial velocity is underpredicted by the three models. LES model and RNG k-ɛ model predict the better tangential velocity and axial velocity, respectively. RNG k-ɛ model is recommended for the simulation of the flow in an unbaffled stirred tank with magnetic rod due to its computational effort.
Modeling and testing of cryo-adsorbent hydrogen storage tanks with improved thermal isolation
NASA Astrophysics Data System (ADS)
Raymond, Alexander William; Reiter, Joseph
2012-06-01
One storage concept for hydrogen-fueled vehicles is physical adsorption of hydrogen at cryogenic temperatures (nominally 80 K). During long idle periods, parasitic heat transfer from the environment induces desorption to the tank void volume. This desorption increases tank pressure such that it must be vented. To reduce the amount of fuel lost to venting, parasitic heating is minimized using multi-layer vacuum insulation and thermally isolating structures. A model is developed to predict the amount of conduction through structural supports and hydrogen lines, radiation through multi-layer insulation, and rarified gas conduction in the vacuum jacket of a tank sized for adsorption storage. The model reveals that conduction through structural supports is significant for cases of interest. Thus, two structural support architectures are compared: one utilizing G-10 CR composite and another involving KevlarTM cable. The structural members are sized to support comparable inertial loadings; the overall parasitic heat transfer is found to be as much as 38 percent less for the KevlarTM design. A lumped-parameter tank simulation is used to relate parasitic heat transfer to dormancy time and venting rate. The results of thermal testing of a sub-scale tank simulator are compared with model predictions.
Pike, J.; Reboul, S.
2015-06-01
SRS High Level Waste Tank Farm personnel rely on conductivity probes for detection of incipient overflow conditions in waste tanks. Minimal information is available concerning the sensitivity that must be achieved such that that liquid detection is assured. Overly sensitive electronics results in numerous nuisance alarms for these safety-related instruments. In order to determine the minimum sensitivity required of the probe, Tank Farm Engineering personnel need adequate conductivity data to improve the existing designs. Little or no measurements of liquid waste conductivity exist; however, the liquid phase of the waste consists of inorganic electrolytes for which the conductivity may be calculated. Savannah River Remediation (SRR) Tank Farm Facility Engineering requested SRNL to determine the conductivity of the supernate resident in SRS waste Tank 40 experimentally as well as computationally. In addition, SRNL was requested to develop a correlation, if possible, that would be generally applicable to liquid waste resident in SRS waste tanks. A waste sample from Tank 40 was analyzed for composition and electrical conductivity as shown in Table 4-6, Table 4-7, and Table 4-9. The conductivity for undiluted Tank 40 sample was 0.087 S/cm. The accuracy of OLI Analyzer™ was determined using available literature data. Overall, 95% of computed estimates of electrical conductivity are within ±15% of literature values for component concentrations from 0 to 15 M and temperatures from 0 to 125 °C. Though the computational results are generally in good agreement with the measured data, a small portion of literature data deviates as much as ±76%. A simplified model was created that can be used readily to estimate electrical conductivity of waste solution in computer spreadsheets. The variability of this simplified approach deviates up to 140% from measured values. Generally, this model can be applied to estimate the conductivity within a factor of two. The comparison of the
Felmy, Andrew R.; Mason, Marvin; Qafoku, Odeta; Xia, Yuanxian; Wang, Zheming; MacLean, Graham
2003-03-27
Developing accurate thermodynamic models for predicting the chemistry of the high-level waste tanks at Hanford is an extremely daunting challenge in electrolyte and radionuclide chemistry. These challenges stem from the extremely high ionic strength of the tank waste supernatants, presence of chelating agents in selected tanks, wide temperature range in processing conditions and the presence of important actinide species in multiple oxidation states. This presentation summarizes progress made to date in developing accurate models for these tank waste solutions, how these data are being used at Hanford and the important challenges that remain. New thermodynamic measurements on Sr and actinide complexation with specific chelating agents (EDTA, HEDTA and gluconate) will also be presented.
VizieR Online Data Catalog: A grid of 1D low-mass star formation models (Vaytet+, 2017)
NASA Astrophysics Data System (ADS)
Vaytet, N.; Haugbolle, T.
2016-11-01
We ran 143 1D simulations of gravitationally collapsing Bonnor-Ebert spheres, varying the initial mass, radius and temperature of the parent cloud. The properties of the first and second Larson cores are reported. The simulation outputs for each run are provided (one separate file per snapshot), as well as the initial parameters and core properties in a summary tablec1.dat. All the data from the simulations (figures and raw data for every output) are publicly available at this address: http://starformation.hpc.ku.dk/grid-of-protostars. (2 data files).
Modeling of a lot scale rainwater tank system in XP-SWMM: a case study in Western Sydney, Australia.
van der Sterren, Marlène; Rahman, Ataur; Ryan, Garry
2014-08-01
Lot scale rainwater tank system modeling is often used in sustainable urban storm water management, particularly to estimate the reduction in the storm water run-off and pollutant wash-off at the lot scale. These rainwater tank models often cannot be adequately calibrated and validated due to limited availability of observed rainwater tank quantity and quality data. This paper presents calibration and validation of a lot scale rainwater tank system model using XP-SWMM utilizing data collected from two rainwater tank systems located in Western Sydney, Australia. The modeling considers run-off peak and volume in and out of the rainwater tank system and also a number of water quality parameters (Total Phosphorus (TP), Total Nitrogen (TN) and Total Solids (TS)). It has been found that XP-SWMM can be used successfully to develop a lot scale rainwater system model within an acceptable error margin. It has been shown that TP and TS can be predicted more accurately than TN using the developed model. In addition, it was found that a significant reduction in storm water run-off discharge can be achieved as a result of the rainwater tank up to about one year average recurrence interval rainfall event. The model parameter set assembled in this study can be used for developing lot scale rainwater tank system models at other locations in the Western Sydney region and in other parts of Australia with necessary adjustments for the local site characteristics.
Thermal model development and validation for rapid filling of high pressure hydrogen tanks
Johnson, Terry A.; Bozinoski, Radoslav; Ye, Jianjun; Sartor, George; Zheng, Jinyang; Yang, Jian
2015-06-30
This paper describes the development of thermal models for the filling of high pressure hydrogen tanks with experimental validation. Two models are presented; the first uses a one-dimensional, transient, network flow analysis code developed at Sandia National Labs, and the second uses the commercially available CFD analysis tool Fluent. These models were developed to help assess the safety of Type IV high pressure hydrogen tanks during the filling process. The primary concern for these tanks is due to the increased susceptibility to fatigue failure of the liner caused by the fill process. Thus, a thorough understanding of temperature changes of the hydrogen gas and the heat transfer to the tank walls is essential. The effects of initial pressure, filling time, and fill procedure were investigated to quantify the temperature change and verify the accuracy of the models. In this paper we show that the predictions of mass averaged gas temperature for the one and three-dimensional models compare well with the experiment and both can be used to make predictions for final mass delivery. Furthermore, due to buoyancy and other three-dimensional effects, however, the maximum wall temperature cannot be predicted using one-dimensional tools alone which means that a three-dimensional analysis is required for a safety assessment of the system.
Thermal model development and validation for rapid filling of high pressure hydrogen tanks
Johnson, Terry A.; Bozinoski, Radoslav; Ye, Jianjun; ...
2015-06-30
This paper describes the development of thermal models for the filling of high pressure hydrogen tanks with experimental validation. Two models are presented; the first uses a one-dimensional, transient, network flow analysis code developed at Sandia National Labs, and the second uses the commercially available CFD analysis tool Fluent. These models were developed to help assess the safety of Type IV high pressure hydrogen tanks during the filling process. The primary concern for these tanks is due to the increased susceptibility to fatigue failure of the liner caused by the fill process. Thus, a thorough understanding of temperature changes ofmore » the hydrogen gas and the heat transfer to the tank walls is essential. The effects of initial pressure, filling time, and fill procedure were investigated to quantify the temperature change and verify the accuracy of the models. In this paper we show that the predictions of mass averaged gas temperature for the one and three-dimensional models compare well with the experiment and both can be used to make predictions for final mass delivery. Furthermore, due to buoyancy and other three-dimensional effects, however, the maximum wall temperature cannot be predicted using one-dimensional tools alone which means that a three-dimensional analysis is required for a safety assessment of the system.« less
Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks in Reduced Gravity
NASA Technical Reports Server (NTRS)
Hedayat, Ali; Lopez, Alfredo; Grayson, Gary D.; Chandler, Frank O.; Hastings, Leon J.
2008-01-01
A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in low gravity. Pressure control is provided by an axial jet thermodynamic vent system (TVS) centered within the vessel that injects cooler liquid into the tank, mixing the contents and reducing tank pressure. The two-phase cryogenic tank model considers liquid hydrogen in its own vapor with liquid density varying with temperature only and a fully compressible ullage. The axisymmetric model is developed using a custom version of the commercially available FLOW-3D software and simulates low gravity extrapolations of engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage Technology Demonstrator (STUSTD) program. Model results illustrate that stable low gravity liquid-gas interfaces are maintained during all phases of the pressure control cycle. Steady and relatively smooth ullage pressurization rates are predicted. This work advances current low gravity CFD modeling capabilities for cryogenic pressure control and aids the development of a low cost CFD-based design process for space hardware.
Thermal Modeling and Analysis of a Cryogenic Tank Design Exposed to Extreme Heating Profiles
NASA Technical Reports Server (NTRS)
Stephens, Craig A.; Hanna, Gregory J.
1991-01-01
A cryogenic test article, the Generic Research Cryogenic Tank, was designed to qualitatively simulate the thermal response of transatmospheric vehicle fuel tanks exposed to the environment of hypersonic flight. One-dimensional and two-dimensional finite-difference thermal models were developed to simulate the thermal response and assist in the design of the Generic Research Cryogenic Tank. The one-dimensional thermal analysis determined the required insulation thickness to meet the thermal design criteria and located the purge jacket to eliminate the liquefaction of air. The two-dimensional thermal analysis predicted the temperature gradients developed within the pressure-vessel wall, estimated the cryogen boiloff, and showed the effects the ullage condition has on pressure-vessel temperatures. The degree of ullage mixing, location of the applied high-temperature profile, and the purge gas influence on insulation thermal conductivity had significant effects on the thermal behavior of the Generic Research Cryogenic Tank. In addition to analysis results, a description of the Generic Research Cryogenic Tank and the role it will play in future thermal structures and transatmospheric vehicle research at the NASA Dryden Flight Research Facility is presented.
1/12-scale physical modeling experiments in support of tank 241-SY- 101 hydrogen mitigation
Fort, J.A.; Bamberger, J.A.; Bates, J.M.; Enderlin, C.W.; Elmore, M.R.
1993-01-01
Hanford tank 241-SY-101 is a 75-ft-dia double-shell tank that contains approximately 1.1 M gal of radioactive fuel reprocessing waste. Core samples have shown that the tank contents are separated into two main layers, a article laden supernatant liquid at the top of the tank and a more dense slurry on the bottom. Two additional layers may be present, one being a potentially thick sludge lying beneath the slurry at the bottom of the tank and the other being the crust that has formed on the surface of the supernatant liquid. The supernatant is more commonly referred to as the convective layer and the slurry as the non-convective layer. Accumulation of gas (partly hydrogen) in the non-convective layer is suspected to be the key mechanism behind the gas burp phenomena, and several mitigation schemes are being developed to encourage a more uniform gas release rate (Benegas 1992). To support the full-scale hydraulic mitigation test, scaled experiments were performed to satisfy two objectives: 1. provide an experimental database for numerical- model validation; 2. establish operating parameter values required to mobilize the settled solids and maintain the solids in suspension.
Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data
Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.
2007-05-23
This report was revised in May 2007 to correct values in Section 3.4.1.7, second paragraph, last sentence; 90Sr values in Tables 3.22 and 3.32; and 99Tc values Table 4.3 and in Chapter 5. In addition, the tables in Appendix F were updated to reflect corrections to the 90Sr values. The rest of the text remains unchanged from the original report issued in May 2005. CH2M HILL is producing risk/performance assessments to support the closure of single-shell tanks at the DOE's Hanford Site. As part of this effort, staff at PNNL were asked to develop release models for contam¬inants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. This report provides the information developed by PNNL.
NASA Astrophysics Data System (ADS)
Malkov, Mikhail; Diamond, Patrick; Miki, Kazuhiro
2013-10-01
The LH transition crucially depends on the heat and particle deposition, transport and electric field shear suppression. Despite the inhomogeneity of these phenomena, a popular 0D predator-prey model seems to capture the essential transition dynamics, including the limit cycle pre-H-mode oscillations (or I-mode). However, its predictions regarding hysteresis are inconclusive. This is understandable at least because of the known deep fuel lowering of the transition threshold. The readily available fueling devices are the edge neutral penetration and an internal deposition via the supersonic molecular beam injection (SMBI). This suggests a minimal extension of the 0D model by using bi-modal particle distributions. To formulate this extension accurately, a step-by-step comparison with a 1D treatment is required. Fortunately a suitable 1D numerical model has been recently developed specifically for the LH transition studies. In this work, we use the 1D model for the following purposes. First, we explore fueling effects as occurring both by edge neutral penetration, and internal deposition (SMBI) at a finite depth within the separatrix. Second, as the 0D model responds positively to the oscillating heating power, we include a periodic repetitive SMBI firing. Supported by the US DoE.
Papazoglou, Anna; Soos, Julien; Lundt, Andreas; Wormuth, Carola; Ginde, Varun Raj; Müller, Ralf; Henseler, Christina; Broich, Karl; Xie, Kan
2016-01-01
Alzheimer's disease (AD) is a multifactorial disorder leading to progressive memory loss and eventually death. In this study an APPswePS1dE9 AD mouse model has been analyzed using implantable video-EEG radiotelemetry to perform long-term EEG recordings from the primary motor cortex M1 and the hippocampal CA1 region in both genders. Besides motor activity, EEG recordings were analyzed for electroencephalographic seizure activity and frequency characteristics using a Fast Fourier Transformation (FFT) based approach. Automatic seizure detection revealed severe electroencephalographic seizure activity in both M1 and CA1 deflection in APPswePS1dE9 mice with gender-specific characteristics. Frequency analysis of both surface and deep EEG recordings elicited complex age, gender, and activity dependent alterations in the theta and gamma range. Females displayed an antithetic decrease in theta (θ) and increase in gamma (γ) power at 18-19 weeks of age whereas related changes in males occurred earlier at 14 weeks of age. In females, theta (θ) and gamma (γ) power alterations predominated in the inactive state suggesting a reduction in atropine-sensitive type II theta in APPswePS1dE9 animals. Gender-specific central dysrhythmia and network alterations in APPswePS1dE9 point to a functional role in behavioral and cognitive deficits and might serve as early biomarkers for AD in the future. PMID:27840743
Zhang, Damao; Wang, Zhien; Heymsfield, Andrew J.; Fan, Jiwen; Luo, Tao
2014-10-01
Measurement of ice number concentration in clouds is important but still challenging. Stratiform mixed-phase clouds (SMCs) provide a simple scenario for retrieving ice number concentration from remote sensing measurements. The simple ice generation and growth pattern in SMCs offers opportunities to use cloud radar reflectivity (Ze) measurements and other cloud properties to infer ice number concentration quantitatively. To understand the strong temperature dependency of ice habit and growth rate quantitatively, we develop a 1-D ice growth model to calculate the ice diffusional growth along its falling trajectory in SMCs. The radar reflectivity and fall velocity profiles of ice crystals calculated from the 1-D ice growth model are evaluated with the Atmospheric Radiation Measurements (ARM) Climate Research Facility (ACRF) ground-based high vertical resolution radar measurements. Combining Ze measurements and 1-D ice growth model simulations, we develop a method to retrieve the ice number concentrations in SMCs at given cloud top temperature (CTT) and liquid water path (LWP). The retrieved ice concentrations in SMCs are evaluated with in situ measurements and with a three-dimensional cloud-resolving model simulation with a bin microphysical scheme. These comparisons show that the retrieved ice number concentrations are within an uncertainty of a factor of 2, statistically.
NASA Astrophysics Data System (ADS)
Wittkowski, M.; Chiavassa, A.; Freytag, B.; Scholz, M.; Höfner, S.; Karovicova, I.; Whitelock, P. A.
2016-03-01
Aims: We aim at comparing spectro-interferometric observations of Mira variable asymptotic giant branch (AGB) stars with the latest 1D dynamic model atmospheres based on self-excited pulsation models (CODEX models) and with 3D dynamic model atmospheres including pulsation and convection (CO5BOLD models) to better understand the processes that extend the molecular atmosphere to radii where dust can form. Methods: We obtained a total of 20 near-infrared K-band spectro-interferometric snapshot observations of the Mira variables o Cet, R Leo, R Aqr, X Hya, W Vel, and R Cnc with a spectral resolution of about 1500. We compared observed flux and visibility spectra with predictions by CODEX 1D dynamic model atmospheres and with azimuthally averaged intensities based on CO5BOLD 3D dynamic model atmospheres. Results: Our visibility data confirm the presence of spatially extended molecular atmospheres located above the continuum radii with large-scale inhomogeneities or clumps that contribute a few percent of the total flux. The detailed structure of the inhomogeneities or clumps show a variability on time scales of 3 months and above. Both modeling attempts provided satisfactory fits to our data. In particular, they are both consistent with the observed decrease in the visibility function at molecular bands of water vapor and CO, indicating a spatially extended molecular atmosphere. Observational variability phases are mostly consistent with those of the best-fit CODEX models, except for near-maximum phases, where data are better described by near-minimum models. Rosseland angular diameters derived from the model fits are broadly consistent between those based on the 1D and the 3D models and with earlier observations. We derived fundamental parameters including absolute radii, effective temperatures, and luminosities for our sources. Conclusions: Our results provide a first observational support for theoretical results that shocks induced by convection and pulsation in the
CFD Modeling of Helium Pressurant Effects on Cryogenic Tank Pressure Rise Rates in Normal Gravity
NASA Technical Reports Server (NTRS)
Grayson, Gary; Lopez, Alfredo; Chandler, Frank; Hastings, Leon; Hedayat, Ali; Brethour, James
2007-01-01
A recently developed computational fluid dynamics modeling capability for cryogenic tanks is used to simulate both self-pressurization from external heating and also depressurization from thermodynamic vent operation. Axisymmetric models using a modified version of the commercially available FLOW-3D software are used to simulate actual physical tests. The models assume an incompressible liquid phase with density that is a function of temperature only. A fully compressible formulation is used for the ullage gas mixture that contains both condensable vapor and a noncondensable gas component. The tests, conducted at the NASA Marshall Space Flight Center, include both liquid hydrogen and nitrogen in tanks with ullage gas mixtures of each liquid's vapor and helium. Pressure and temperature predictions from the model are compared to sensor measurements from the tests and a good agreement is achieved. This further establishes the accuracy of the developed FLOW-3D based modeling approach for cryogenic systems.
Development of a flocculation sub-model for a 3-D CFD model based on rectangular settling tanks.
Gong, M; Xanthos, S; Ramalingam, K; Fillos, J; Beckmann, K; Deur, A; McCorquodale, J A
2011-01-01
To assess performance and evaluate alternatives to improve the efficiency of rectangular Gould II type final settling tanks (FSTs), New York City Department of Environmental Protection and City College of NY developed a 3D computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Fluent 6.3.26™ was the base platform for the computational fluid dynamics (CFD) model, for which sub-models of the SS settling characteristics, turbulence, flocculation and rheology were incorporated. This was supplemented by field and bench scale experiments to quantify the coefficients integral to the sub-models. The 3D model developed can be used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs. Flocculation in the front half of the rectangular tank especially in the region before and after the inlet baffle is one of the vital parameters that influences the capture efficiency of SS. Flocculation could be further improved by capturing medium and small size particles by creating an additional zone with an in-tank baffle. This was one of the methods that was adopted in optimizing the performance of the tank where the CCNY 3D CFD model was used to locate the in-tank baffle position. This paper describes the development of the flocculation sub-model and the relationship of the flocculation coefficients in the known Parker equation to the initial mixed liquor suspended solids (MLSS) concentration X0. A new modified equation is proposed removing the dependency of the breakup coefficient to the initial value of X0 based on preliminary data using normal and low concentration mixed liquor suspended solids values in flocculation experiments performed.
Karri, Naveen K.; Rinker, Michael W.; Johnson, Kenneth I.; Bapanapalli, Satish K.
2012-07-01
The single-shell tanks at the Hanford Site (in Washington State, USA) were constructed between 1943 and 1964 and are well beyond their estimated 25 year design life. This article discusses the structural analysis approach and modeling challenges encountered during the ongoing analysis of record for evaluating the structural integrity of the single-shell tanks. There are several geometrical and material nonlinearities and uncertainties to be dealt with while performing the modern finite element analysis of these tanks. The analysis takes into account the temperature history of the tanks and allowable mechanical operating loads for proper estimation of creep strains and thermal degradation of material properties. The loads prescribed in the analysis of record models also include anticipated loads that may occur during waste retrieval and closure. Due to uncertainty in a number of modeling details, sensitivity studies were conducted to address questions related to boundary conditions that realistically or conservatively represent the influence of surrounding tanks in a tank farm, the influence of backfill excavation slope, the extent of backfill and the total extent of undisturbed soil surrounding the backfill. Because of the limited availability of data on the thermal and operating history for many of the individual tanks, some of the data was assumed or interpolated. However, the models developed for the analysis of record represent the bounding scenarios and include the loading conditions that the tanks were subjected to or anticipated. The modeling refinement techniques followed in the analysis of record resulted in conservative estimates for force and moment demands at various sections in the concrete tanks. This article discusses the modeling aspects related to Type-II and Type-III single-shell tanks. The modeling techniques, methodology and evaluation criteria developed for evaluating the structural integrity of single-shell tanks at Hanford are in general
AVVAM-1 (Armored Vehicle Vulnerability Analysis Model) and Tank Vulnerability Sensitivity Studies
1973-01-01
Ground , Maryland 0 Introduction I AVVAM-I ( Armored Vehicle Vulnerability Analysis Model -first version) is a conceptuil model-and associateS digital... measure of the ballistic shielding provided by a tank component. *The higher this value the harder it is for a spall fragment to perforate the component...in vulnerability to ballistic damage from behind-the- armor frag- ments and in the ability of noncritical components to provide ballistic shielding for
Physics-Based Fragment Acceleration Modeling for Pressurized Tank Burst Risk Assessments
NASA Technical Reports Server (NTRS)
Manning, Ted A.; Lawrence, Scott L.
2014-01-01
As part of comprehensive efforts to develop physics-based risk assessment techniques for space systems at NASA, coupled computational fluid and rigid body dynamic simulations were carried out to investigate the flow mechanisms that accelerate tank fragments in bursting pressurized vessels. Simulations of several configurations were compared to analyses based on the industry-standard Baker explosion model, and were used to formulate an improved version of the model. The standard model, which neglects an external fluid, was found to agree best with simulation results only in configurations where the internal-to-external pressure ratio is very high and fragment curvature is small. The improved model introduces terms that accommodate an external fluid and better account for variations based on circumferential fragment count. Physics-based analysis was critical in increasing the model's range of applicability. The improved tank burst model can be used to produce more accurate risk assessments of space vehicle failure modes that involve high-speed debris, such as exploding propellant tanks and bursting rocket engines.
Anomalous Fourier's Law and Long Range Correlations in a 1D Non-momentum Conserving Mechanical Model
NASA Astrophysics Data System (ADS)
Gerschenfeld, A.; Derrida, B.; Lebowitz, J. L.
2010-12-01
We study by means of numerical simulations the velocity reversal model, a one-dimensional mechanical model of heat transport introduced in 1985 by Ianiro and Lebowitz. Our numerical results indicate that this model, which does not conserve momentum, exhibits nevertheless an anomalous Fourier's law similar to the ones previously observed in momentum-conserving models. This disagrees with what can be expected by solving the Boltzmann equation (BE) for this system. The pair correlation velocity field also looks very different from the correlations usually seen in diffusive systems, and shares some similarity with those of momentum-conserving heat transport models.
Detailed modeling of sloshing in satellites tank at low Bond numbers
NASA Astrophysics Data System (ADS)
Lepilliez, Mathieu; Tanguy, Sebastien; Interface Team
2015-11-01
Consumption of ergols is a critical issue regarding the whole lifetime of a satellite. During maneuvers in mission phases, the Helium bubble used to pressurize the tank can move freely inside, thus generating movement of the center of mass, and sloshing which can disrupt the control of the satellite. In this study we present numerical results obtained from CFD computation, using an Immersed Interface Method to model the tank with a level-set approach for both liquid-gas interface and solid-fluid interface. A parametric study is proposed to observe the influence of the Bond number on resulting forces and torques generated on the tank. One can observe different steps during the maneuvers under microgravity: the first part is dominated by accelerations and volume forces, which flatten the bubble on the hydrophilic tank wall. When the forcing stops, the bubble bounces back, generating sloshing by moving under the influence of inertia and capillary effects. Finally viscous effects damp the sloshing by dissipating the kinetic energy of the bubble. Those results are compared to actual in-flight data for different typical maneuvers on forces and torques, allowing us to characterize the period and damping of the sloshing. CNES/ Airbus Defence & Space funding.
Modeling the system dynamics for nutrient removal in an innovative septic tank media filter.
Xuan, Zhemin; Chang, Ni-Bin; Wanielista, Martin
2012-05-01
A next generation septic tank media filter to replace or enhance the current on-site wastewater treatment drainfields was proposed in this study. Unit operation with known treatment efficiencies, flow pattern identification, and system dynamics modeling was cohesively concatenated in order to prove the concept of a newly developed media filter. A multicompartmental model addressing system dynamics and feedbacks based on our assumed microbiological processes accounting for aerobic, anoxic, and anaerobic conditions in the media filter was constructed and calibrated with the aid of in situ measurements and the understanding of the flow patterns. Such a calibrated system dynamics model was then applied for a sensitivity analysis under changing inflow conditions based on the rates of nitrification and denitrification characterized through the field-scale testing. This advancement may contribute to design such a drainfield media filter in household septic tank systems in the future.
Verley, Jason C.; Axness, Carl L.; Hembree, Charles Edward; Keiter, Eric Richard; Kerr, Bert
2012-04-01
Photocurrent generated by ionizing radiation represents a threat to microelectronics in radiation environments. Circuit simulation tools such as SPICE [1] can be used to analyze these threats, and typically rely on compact models for individual electrical components such as transistors and diodes. Compact models consist of a handful of differential and/or algebraic equations, and are derived by making simplifying assumptions to any of the many semiconductor transport equations. Historically, many photocurrent compact models have suffered from accuracy issues due to the use of qualitative approximation, rather than mathematically correct solutions to the ambipolar diffusion equation. A practical consequence of this inaccuracy is that a given model calibration is trustworthy over only a narrow range of operating conditions. This report describes work to produce improved compact models for photocurrent. Specifically, an analytic model is developed for epitaxial diode structures that have a highly doped subcollector. The analytic model is compared with both numerical TCAD calculations, as well as the compact model described in reference [2]. The new analytic model compares well against TCAD over a wide range of operating conditions, and is shown to be superior to the compact model from reference [2].
Alastruey, Jordi; Khir, Ashraf W.; Matthys, Koen S.; Segers, Patrick; Sherwin, Spencer J.; Verdonck, Pascal R.; Parker, Kim H.; Peiró, Joaquim
2011-01-01
The accuracy of the nonlinear one-dimensional (1-D) equations of pressure and flow wave propagation in Voigt-type visco-elastic arteries was tested against measurements in a well-defined experimental 1:1 replica of the 37 largest conduit arteries in the human systemic circulation. The parameters required by the numerical algorithm were directly measured in the in vitro setup and no data fitting was involved. The inclusion of wall visco-elasticity in the numerical model reduced the underdamped high-frequency oscillations obtained using a purely elastic tube law, especially in peripheral vessels, which was previously reported in this paper [Matthys et al., 2007. Pulse wave propagation in a model human arterial network: Assessment of 1-D numerical simulations against in vitro measurements. J. Biomech. 40, 3476–3486]. In comparison to the purely elastic model, visco-elasticity significantly reduced the average relative root-mean-square errors between numerical and experimental waveforms over the 70 locations measured in the in vitro model: from 3.0% to 2.5% (p<0.012) for pressure and from 15.7% to 10.8% (p<0.002) for the flow rate. In the frequency domain, average relative errors between numerical and experimental amplitudes from the 5th to the 20th harmonic decreased from 0.7% to 0.5% (p<0.107) for pressure and from 7.0% to 3.3% (p<10−6) for the flow rate. These results provide additional support for the use of 1-D reduced modelling to accurately simulate clinically relevant problems at a reasonable computational cost. PMID:21724188
Deterministic model for an internal melt ice-on-coil thermal storage tank
Neto, J.H.M.; Krarti, M.
1997-12-31
A deterministic numerical model, based on a quasi-steady-state approach, is developed for an internal melt ice-on-coil thermal storage tank with a built-in spiral coil tubing heat exchanger having a counterflow configuration and quiescent water around the coils. This model is able to simulate both charging and discharging modes, taking into account the overlapping phenomenon that occurs due to the superposition of the ice layers during freezing as well as the superposition of the water layers during melting. The developed model accounts for the cooldown of the water earlier during the charging period and the warm-up of the water later during the discharging period. The input parameters include the geometric dimensions of the tank, the secondary fluid temperature and its flow rate entering the tank, the number of segments along the coil, and the time step. The model determines the heat transfer rates, the inventory of the ice, and other output parameters such as temperatures and ice/water radius. This model can be used by manufacturers and engineers for design and simulation purposes.
Modeling and Analysis of Chill and Fill Processes for the EDU Tank
NASA Technical Reports Server (NTRS)
Hedayat, A.; Cartagena, W.; Majumdar, A. K.; Leclair, A. C.
2015-01-01
NASA's future missions may require long-term storage and transfer of cryogenic propellants. The Engineering Development Unit (EDU), a NASA in-house effort supported by both Marshall Space Flight Center (MSFC) and Glenn Research Center (GRC), is a Cryogenic Fluid Management (CFM) test article that primarily serves as a manufacturing pathfinder and a risk reduction task for a future CFM payload. The EDU test article, comprises a flight like tank, internal components, insulation, and attachment struts. The EDU is designed to perform integrated passive thermal control performance testing with liquid hydrogen in a space-like vacuum environment. A series of tests, with liquid hydrogen as a testing fluid, was conducted at Test Stand 300 at MSFC during summer of 2014. The objective of this effort was to develop a thermal/fluid model for evaluating the thermodynamic behavior of the EDU tank during the chill and fill processes. Generalized Fluid System Simulation Program (GFSSP), an MSFC in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the chill and fill portion of the testing. The model contained the liquid hydrogen supply source, feed system, EDU tank, and vent system. The modeling description and comparison of model predictions with the test data will be presented in the final paper.
Tank Tests of Model 11-G Flying-boat Hull
NASA Technical Reports Server (NTRS)
Parkinson, J B
1935-01-01
The NACA model 11-G flying-boat hull, a modification of NACA model 11-A was tested over a range of loadings. The planing bottom of model 11-G has a variable-radius flare, or concavity, at the chines in contrast to the straight V planing bottom of model 11-A. The results are given as curves of resistance and trimming moment plotted against speed for various angles of trim. The characteristics of the form at the optimum angles of trim are given in non-dimensional form as curves of resistance coefficient, best trim angle, and trimming-moment coefficient plotted against speed coefficient. As compared with the original form, model 11-G is shown to have higher resistance at all loads and speeds and higher maximum trimming moments at heavy loads. The spray pattern, however, is generally more favorable, indicating that the service performance of model 11-A would be improved by some form of chime flare.
Technology Transfer Automated Retrieval System (TEKTRAN)
Watershed modeling is a key component of watershed management that involves the simulation of hydrological and fluvial processes for predicting flow and sediment transport within a watershed. For practical purposes, most numerical models have been developed to simulate either runoff and soil erosion...
A History of Collapse Factor Modeling and Empirical Data for Cryogenic Propellant Tanks
NASA Technical Reports Server (NTRS)
deQuay, Laurence; Hodge, B. Keith
2010-01-01
One of the major technical problems associated with cryogenic liquid propellant systems used to supply rocket engines and their subassemblies and components is the phenomenon of propellant tank pressurant and ullage gas collapse. This collapse is mainly caused by heat transfer from ullage gas to tank walls and interfacing propellant, which are both at temperatures well below those of this gas. Mass transfer between ullage gas and cryogenic propellant can also occur and have minor to significant secondary effects that can increase or decrease ullage gas collapse. Pressurant gas is supplied into cryogenic propellant tanks in order to initially pressurize these tanks and then maintain required pressures as propellant is expelled from these tanks. The net effect of pressurant and ullage gas collapse is increased total mass and mass flow rate requirements of pressurant gases. For flight vehicles this leads to significant and undesirable weight penalties. For rocket engine component and subassembly ground test facilities this results in significantly increased facility hardware, construction, and operational costs. "Collapse Factor" is a parameter used to quantify the pressurant and ullage gas collapse. Accurate prediction of collapse factors, through analytical methods and modeling tools, and collection and evaluation of collapse factor data has evolved over the years since the start of space exploration programs in the 1950 s. Through the years, numerous documents have been published to preserve results of studies associated with the collapse factor phenomenon. This paper presents a summary and selected details of prior literature that document the aforementioned studies. Additionally other literature that present studies and results of heat and mass transfer processes, related to or providing important insights or analytical methods for the studies of collapse factor, are presented.
An extension of the Savage-Hutter gravity driven granular flow model on arbitrary topography in 1D
NASA Astrophysics Data System (ADS)
Fellin, Wolfgang; Ostermann, Alexander; Staggl, Gregor
2015-04-01
In an implementation of the Savage-Hutter model in a GIS (geographic information system, e.g. GRASS GIS) curvature terms must be accounted for. We extend the work of Bouchut et al. (2003) to include friction between flowing mass and bed, as well as the active/passive earth pressure coefficient to model the behavior of the granular flow according to the original Savage-Hutter idea. Conservation of mass and momentum in curvilinear coordinates are integrated over the flow height yielding a shallow water model. This work is part of the project avaflow: http://www.avaflow.org/ References: F. Bouchut, A. Mangeney-Castelnau, B. Perthame, J.-P. Vilotte, A new model of Saint Venant and Savage-Hutter type for gravity driven shallow water flows, C.R. Acad. Sci. Paris, série I 336 (2003), 531-536.
NASA Astrophysics Data System (ADS)
Yang, Jun; Leconte, Jérémy; Wolf, Eric T.; Goldblatt, Colin; Feldl, Nicole; Merlis, Timothy; Wang, Yuwei; Koll, Daniel D. B.; Ding, Feng; Forget, François; Abbot, Dorian S.
2016-08-01
An accurate estimate of the inner edge of the habitable zone is critical for determining which exoplanets are potentially habitable and for designing future telescopes to observe them. Here, we explore differences in estimating the inner edge among seven one-dimensional radiative transfer models: two line-by-line codes (SMART and LBLRTM) as well as five band codes (CAM3, CAM4_Wolf, LMDG, SBDART, and AM2) that are currently being used in global climate models. We compare radiative fluxes and spectra in clear-sky conditions around G and M stars, with fixed moist adiabatic profiles for surface temperatures from 250 to 360 K. We find that divergences among the models arise mainly from large uncertainties in water vapor absorption in the window region (10 μm) and in the region between 0.2 and 1.5 μm. Differences in outgoing longwave radiation increase with surface temperature and reach 10-20 W m-2 differences in shortwave reach up to 60 W m-2, especially at the surface and in the troposphere, and are larger for an M-dwarf spectrum than a solar spectrum. Differences between the two line-by-line models are significant, although smaller than among the band models. Our results imply that the uncertainty in estimating the insolation threshold of the inner edge (the runaway greenhouse limit) due only to clear-sky radiative transfer is ≈10% of modern Earth’s solar constant (i.e., ≈34 W m-2 in global mean) among band models and ≈3% between the two line-by-line models. These comparisons show that future work is needed that focuses on improving water vapor absorption coefficients in both shortwave and longwave, as well as on increasing the resolution of stellar spectra in broadband models.
Grant, K.E.; Taylor, K.E.; Ellis, J.S.; Wuebbles, D.J.
1987-07-01
The authors have implemented a series of state of the art radiation transport submodels in previously developed one dimensional and two dimensional chemical transport models of the troposphere and stratosphere. These submodels provide the capability of calculating accurate solar and infrared heating rates. They are a firm basis for further radiation submodel development as well as for studying interactions between radiation and model dynamics under varying conditions of clear sky, clouds, and aerosols. 37 refs., 3 figs.
NASA Astrophysics Data System (ADS)
Ryu, Jaiyoung; Hu, Xiao; Shadden, Shawn C.
2014-11-01
The cerebral circulation is unique in its ability to maintain blood flow to the brain under widely varying physiologic conditions. Incorporating this autoregulatory response is critical to cerebral blood flow modeling, as well as investigations into pathological conditions. We discuss a one-dimensional nonlinear model of blood flow in the cerebral arteries that includes coupling of autoregulatory lumped parameter networks. The model is tested to reproduce a common clinical test to assess autoregulatory function - the carotid artery compression test. The change in the flow velocity at the middle cerebral artery (MCA) during carotid compression and release demonstrated strong agreement with published measurements. The model is then used to investigate vasospasm of the MCA, a common clinical concern following subarachnoid hemorrhage. Vasospasm was modeled by prescribing vessel area reduction in the middle portion of the MCA. Our model showed similar increases in velocity for moderate vasospasms, however, for serious vasospasm (~ 90% area reduction), the blood flow velocity demonstrated decrease due to blood flow rerouting. This demonstrates a potentially important phenomenon, which otherwise would lead to false-negative decisions on clinical vasospasm if not properly anticipated.
Smith, R; Taha, T; Cui, Z F
2005-01-01
Tubular membrane ultrafiltration and microfiltration are important industrial separation and concentration processes. Process optimisation requires reduction of membrane build-up. Gas slug introduction has been shown to be a useful approach for flux enhancement. However, process quantification is required for design and optimisation. In this work we employ a non-porous wall CFD model to quantify hydrodynamics in the two-phase slug flow process. Mass transfer is subsequently quantified from wall shear stress, which was determined from the CFD. The mass transfer model is an improved one-dimensional boundary layer model, which empirically incorporates effects of wall suction and analytically includes edge effects for circular conduits. Predicted shear stress profiles are in agreement with experimental results and flux estimates prove more reliable than that from previous models. Previous models ignored suction effects and employed less rigorous fluid property inclusion, which ultimately led to under-predictive flux estimates. The presented model offers reliable process design and optimisation criteria for gas-sparged tubular membrane ultrafiltration.
Experimental validation of a numerical model for an internal melt ice-on-coil thermal storage tank
Neto, J.H.M.; Krarti, M.
1997-12-31
An internal melt ice-on-coil thermal storage tank was instrumented and tested over various inlet conditions of secondary fluid temperature and flow rate in a full-scale heating, ventilating, and air-conditioning (HVAC) laboratory. Five charging/discharging cycle tests were performed. The measured data for one typical charging/discharging cycle were used to validate a numerical model developed for analyzing internal melt ice-on-coil ice storage tanks. The validation analysis was based on the secondary fluid temperature leaving the tank, the secondary fluid heat transfer rates, the inventory of ice, the temperature of the secondary fluid at four representative locations along the coil, the temperature of the water and the ice at three representative locations inside the tank, and secondary fluid pressure drop through the tank. In general, good agreement was found between the predicted and the measured data.
NASA Technical Reports Server (NTRS)
Healy, Frederick M.
1958-01-01
A supplementary investigation to determine the effect of external fuel tanks on the spin and recovery characteristics of a l/28-scale model of the North American FJ-4 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The model had been extensively tested previously (NACA Research Memorandum SL38A29) and therefore only brief tests were made to evaluate the effect of tank installation. Erect spin tests of the model indicate that flat-type spins-are more prevalent with 200-gallon external fuel tanks than with tanks not installed. The recovery technique determined for spins without tanks, rudder reversal to full against the spin accompanied by simultaneous movement of ailerons to full with the spin, is recommended for spins encountered with external tanks installed. If inverted spins are encountered with external tanks installed, the tanks should be jettisoned and recovery attempted by rudder reversal to full against the spin with ailerons maintained at neutral.
NASA Astrophysics Data System (ADS)
Bhattacharya, A.; Mandal, M.
2014-12-01
Model spin-up is the process through which the model is adequately equilibrated to ensure balance between the mass fields and velocity fields. In this study, an offline 1-D Noah land surface model (LSM) has been used to investigate the impact of soil moisture on the model spin up at Kharagpur, India which is a site in monsoonal region. The model is integrated recursively for 3-years to assess its spin-up behavior. Several numerical experiments are performed to investigate the impact of initial soil moisture and subsequent dry or wet condition on model spin-up. These include simulations with different initial soil moisture content (observed soil moisture; dry soil; moderately wet soil; saturated soil), simulations initialized before different rain conditions (no rain; infrequent rain; continuous rain) and simulations initialized in different seasons (Winter, Spring, Summer/Pre-Monsoon, Monsoon and Autumn). It is noted that the model has significantly longer spin-up when initialized with very low initial soil moisture content than with higher soil moisture content. It is also seen that in general, simulations initialized just before a continuous rainfall event have the least spin-up time. In a region affected by the monsoon, such as Kharagpur, this observation is reinforced by the results from the simulations initialized in different seasons. It is seen that for monsoonal region, the model spin-up time is least for simulations initialized during Summer/Pre-monsoon. Model initialized during the Monsoon has a longer spin-up than that initialized in any other season. It appears that the model has shorter spin-up if it reaches the equilibrium state predominantly via drying process. It is also observed that the spin-up of offline 1-D Noah LSM may be as low as two months under quasi-equilibrium condition if the initial soil moisture content and time of start of simulations are chosen carefully.
Modelling of stratification in cryogenic launch vehicle tanks in a fast engineering tool
NASA Astrophysics Data System (ADS)
van Foreest, Arnold
Modelling of stratification in cryogenic launch vehicle tanks in a fast engineering tool Thermal stratification in cryogenic launch vehicle tanks can lead to several problems, such as sudden pressure drops in the tank due to sloshing of the stratified liquid or cavitation in rocket engine turbopumps. To obtain an optimal stage design, the stratification process muss be taken into account. Currently, stratification is often modelled by 3D CFD solvers, which is an extremely time consuming process. Analytical models do exists but are inaccurate. This paper will show how the currently existing analytical models are improved, by using experimental data and results obtained from numerical calculations using the 3D CFD tool FLOW 3D. The goal is to be able to model a stratification process of a few hundred seconds in just a few seconds of CPU time, so about a factor 100 faster than the physical process takes. A simulation using a 3D flow solver can take multiple days. Setting up the model for a 3D flow solver can even take longer. Therefore it would be a big advantage to have fast engineering tools describing the process so that stratification can be taken into account in the preliminary design phase. The stratification process has been investigated experimentally at ZARM (Centre of Applied Spaceflight and Microgravity), using a closed tank filled with liquid nitrogen. Due to unavoidable heat leaks from the surrounding, the liquid will start to heat up and thermal layers will form. The experiments are simulated using the commercial 3D flow solver "FLOW 3D". Once satisfying numerical results have been obtained, the stratification process can be investigated in more detail. The dimensioning parameters can be determined and their influence can be quantified. From these analyses it has been found that for example heat conduction through the tank wall in tangential direction has a big impact on the formation of thermal layers. The currently available analytical models for
Karri, Naveen K.; Rinker, Michael W.; Johnson, Kenneth I.; Bapanapalli, Satish K.
2012-03-01
Abstract: A total of 149 tanks out of 177 at the Hanford Site (in Washington State, USA) belong to the first generation of underground nuclear waste storage tanks known as single shell tanks (SSTs). These tanks were constructed between 1943 and 1964 and are well beyond their design life. All the SSTs had been removed from active service by November 1980 and have been later interim stabilized by removing the pumpable liquids. The remaining waste in the tanks is in the form of salt cake and sludge awaiting r permanent disposal.. The evaluation of the structural integrity of these tanks is of utmost importance not only for the continued safe storage of the waste until waste retrieval and closure, but also to assure safe retrieval and closure operations. This article discusses the structural analysis approach, modeling challenges and issues encountered during the ongoing analysis of record (AOR) for evaluating the structural integrity of the SSTs. There are several geometrical and material nonlinearities and uncertainties to be dealt with while performing the modern finite element analysis of these tanks. Several studies were conducted to refine the models in order to minimize modeling artifacts introduced by soil arching, boundary effects, concrete cracking, and concrete-soil interface behavior. The analysis takes into account the temperature history of the tanks and allowable mechanical operating loads of these tanks for proper estimation of creep strains and thermal degradation of material properties. The loads imposed in the AOR models also include anticipated loads that these tanks may see during waste retrieval and closure. Due to uncertainty in a number of inputs to the models, sensitivity studies were conducted to address questions related to the boundary conditions to realistically or conservatively represent the influence of surrounding tanks in a tank farm, the influence of backfill excavation slope, the extent of backfill and the total extent of undisturbed
NASA Astrophysics Data System (ADS)
Ireland, Gareth; Petropoulos, George P.; Carlson, Toby N.; Purdy, Sarah
2015-04-01
Sensitivity analysis (SA) consists of an integral and important validatory check of a computer simulation model before it is used to perform any kind of analysis. In the present work, we present the results from a SA performed on the SimSphere Soil Vegetation Atmosphere Transfer (SVAT) model utilising a cutting edge and robust Global Sensitivity Analysis (GSA) approach, based on the use of the Gaussian Emulation Machine for Sensitivity Analysis (GEM-SA) tool. The sensitivity of the following model outputs was evaluated: the ambient CO2 concentration and the rate of CO2 uptake by the plant, the ambient O3 concentration, the flux of O3 from the air to the plant/soil boundary, and the flux of O3 taken up by the plant alone. The most sensitive model inputs for the majority of model outputs were related to the structural properties of vegetation, namely, the Leaf Area Index, Fractional Vegetation Cover, Cuticle Resistance and Vegetation Height. External CO2 in the leaf and the O3 concentration in the air input parameters also exhibited significant influence on model outputs. This work presents a very important step towards an all-inclusive evaluation of SimSphere. Indeed, results from this study contribute decisively towards establishing its capability as a useful teaching and research tool in modelling Earth's land surface interactions. This is of considerable importance in the light of the rapidly expanding use of this model worldwide, which also includes research conducted by various Space Agencies examining its synergistic use with Earth Observation data towards the development of operational products at a global scale. This research was supported by the European Commission Marie Curie Re-Integration Grant "TRANSFORM-EO". SimSphere is currently maintained and freely distributed by the Department of Geography and Earth Sciences at Aberystwyth University (http://www.aber.ac.uk/simsphere). Keywords: CO2 flux, ambient CO2, O3 flux, SimSphere, Gaussian process emulators
Exact First-Passage Exponents of 1D Domain Growth: Relation to a Reaction-Diffusion Model
NASA Astrophysics Data System (ADS)
Derrida, Bernard; Hakim, Vincent; Pasquier, Vincent
1995-07-01
In the zero temperature Glauber dynamics of the ferromagnetic Ising or q-state Potts model, the size of domains is known to grow like t1/2. Recent simulations have shown that the fraction r\\(q,t\\) of spins, which have never flipped up to time t, decays like the power law r\\(q,t\\)~t-θ\\(q\\) with a nontrivial dependence of the exponent θ\\(q\\) on q and on space dimension. By mapping the problem on an exactly soluble one-species coagulation model ( A+A-->A), we obtain the exact expression of θ\\(q\\) in dimension one.
NASA Astrophysics Data System (ADS)
Hoch, J. M.; Bierkens, M. F.; Van Beek, R.; Winsemius, H.; Haag, A.
2015-12-01
Understanding the dynamics of fluvial floods is paramount to accurate flood hazard and risk modeling. Currently, economic losses due to flooding constitute about one third of all damage resulting from natural hazards. Given future projections of climate change, the anticipated increase in the World's population and the associated implications, sound knowledge of flood hazard and related risk is crucial. Fluvial floods are cross-border phenomena that need to be addressed accordingly. Yet, only few studies model floods at the large-scale which is preferable to tiling the output of small-scale models. Most models cannot realistically model flood wave propagation due to a lack of either detailed channel and floodplain geometry or the absence of hydrologic processes. This study aims to develop a large-scale modeling tool that accounts for both hydrologic and hydrodynamic processes, to find and understand possible sources of errors and improvements and to assess how the added hydrodynamics affect flood wave propagation. Flood wave propagation is simulated by DELFT3D-FM (FM), a hydrodynamic model using a flexible mesh to schematize the study area. It is coupled to PCR-GLOBWB (PCR), a macro-scale hydrological model, that has its own simpler 1D routing scheme (DynRout) which has already been used for global inundation modeling and flood risk assessments (GLOFRIS; Winsemius et al., 2013). A number of model set-ups are compared and benchmarked for the simulation period 1986-1996: (0) PCR with DynRout; (1) using a FM 2D flexible mesh forced with PCR output and (2) as in (1) but discriminating between 1D channels and 2D floodplains, and, for comparison, (3) and (4) the same set-ups as (1) and (2) but forced with observed GRDC discharge values. Outputs are subsequently validated against observed GRDC data at Óbidos and flood extent maps from the Dartmouth Flood Observatory. The present research constitutes a first step into a globally applicable approach to fully couple
NASA Technical Reports Server (NTRS)
Schmitt, G. A.; Abreu, V. J.; Hays, P. B.
1981-01-01
Thermal and nonthermal O(1D) number density profiles are calculated. The two populations are assumed to be coupled by a thermalization cross-section which determines the loss and production in the nonthermal and thermal populations, respectively. The sources, sinks and transport of the two populations are used to model volume emission rate profiles at 6300 A. The 6300 A brightness measured by the Visible Airglow Experiment is then used to establish the presence of the nonthermal population and to determine the thermalization cross-section.
NASA Astrophysics Data System (ADS)
Riel, Nicolas; Mercier, Jonathan
2014-05-01
It is now widely accepted that the formation and the evolution of high elevation plateaus such as the Tibet and the Altiplano-Puna are strongly linked to mantel magma underplating at crustal root level and partial melting of the lower crust. Understanding the rheological behavior of the deep continental crust during these episodes is therefore crucial to constrain the evolution of such plateau. In this study we present results obtained from pressure-temperature estimates and thermal modeling of gabbro underplating at crustal root level (25km) in the El Oro Metamorphic Complex (Ecuador). The aim of this study is: (1) to complete previously published P-Tmax estimates in the northern part of the migmatitic unit, close to the magmatic contact with the gabbroic unit, to obtain better constraints on the metamorphic gradient during partial melting, (2) to characterize the effects of melt extraction, latent heat capture and release and a temperature-dependent thermal diffusivity on the thermal evolution of the system using a specifically developed numerical model, and (3) in the light of the thermal modeling results, to discuss the geological processes involved during partial melting of the metasedimentary crust. Our modeling results show that the estimate metamorphic gradient cannot be reproduced when solely taking into account latent heat, melt extraction and thermal-dependent diffusivity. In the light of geological, geochemical and modeling evidence we show that the lower migmatitic unit, controlled by biotite-dehydration melting reactions was subject to convective motion that contributed to lower the metamorphic gradient and rapidly transfer heat upward. For a biotite-rich rock (~20%) containing 15-20% of melt, we estimate the maximum viscosity of the rock that allows convection at ~7.5e17 Pa.s. Our results also suggest that convection can be maintained as long as heat is provided and that temperature lies in the stability field of biotite-dehydration melting (750-900°C).
NASA Technical Reports Server (NTRS)
Perez, Jose G.; Parks, Russel, A.; Lazor, Daniel R.
2012-01-01
The slosh dynamics of propellant tanks can be represented by an equivalent mass-pendulum-dashpot mechanical model. The parameters of this equivalent model, identified as slosh mechanical model parameters, are slosh frequency, slosh mass, and pendulum hinge point location. They can be obtained by both analysis and testing for discrete fill levels. Anti-slosh baffles are usually needed in propellant tanks to control the movement of the fluid inside the tank. Lateral slosh testing, involving both random excitation testing and free-decay testing, are performed to validate the slosh mechanical model parameters and the damping added to the fluid by the anti-slosh baffles. Traditional modal analysis procedures were used to extract the parameters from the experimental data. Test setup of sub-scale tanks will be described. A comparison between experimental results and analysis will be presented.
NASA Astrophysics Data System (ADS)
Valstar, Johan; Rowe, Ed; Konstantina, Moirogiorgou; Giannakis, Giorgos; Nikolaidis, Nikolaos
2014-05-01
explore the complex interactions involved in soil development and change. We were unable to identify appropriately-detailed existing models for plant productivity and for the dynamics of soil aggregation and porosity, and so developed the PROSUM and CAST models, respectively, to simulate these subsystems. Moreover, we applied the BRNS generator to obtain a chemical equilibrium model. These were combined with HYDRUS-1D (water and solute transport), a weathering model (derived from the SAFE model) and a simple bioturbation model. The model includes several feedbacks, such as the effect of soil organic matter on water retention and hydraulic conductivity. We encountered several important challenges when building the integrated model. First, a mechanism was developed that initiates the execution of a single time step for an individual sub-model and accounts for the relevant mass transfers between sub-models. This allows for different and sometimes variable time step duration in the submodels. Secondly, we removed duplicated processes and identified and included relevant solute production terms that had been neglected. The model is being tested against datasets obtained from several Soil Critical Zone Observatories in Europe. This contribution focuses on the design strategy for the model.
Elongated Tetrakaidecahedron Micromechanics Model for Space Shuttle External Tank Foams
NASA Technical Reports Server (NTRS)
Sullivan, Roy M.; Ghosn, Louis J.; Lerch, Bradley A.; Baker, Eric H.
2009-01-01
The results of microstructural characterization studies and physical and mechanical testing of BX-265 and NCFI24-124 foams are reported. A micromechanics model developed previously by the authors is reviewed, and the resulting equations for the elastic constants, the relative density, and the strength of the foam in the principal material directions are presented. The micromechanics model is also used to derive equations to predict the effect of vacuum on the tensile strength and the strains induced by exposure to vacuum. Using a combination of microstructural dimensions and physical and mechanical measurements as input, the equations for the elastic constants and the relative density are applied and the remaining microstructural dimensions are predicted. The predicted microstructural dimensions are in close agreement with the average measured values for both BX-265 and NCFI24-124. With the microstructural dimensions, the model predicts the ratio of the strengths in the principal material directions for both foams. The model is also used to predict the Poisson s ratios, the vacuum-induced strains, and the effect of vacuum on the tensile strengths. However, the comparison of these predicted values with the measured values is not as favorable.
Solid-liquid interdiffusion (SLID) bonding in the Au-In system: experimental study and 1D modelling
NASA Astrophysics Data System (ADS)
Deillon, Léa; Hessler-Wyser, Aïcha; Hessler, Thierry; Rappaz, Michel
2015-12-01
Au-In bonds with a nominal composition of about 60 at.% In were fabricated for use in wafer-level packaging of MEMS. The microstructure of the bonds was studied by scanning electron microscopy. The bond hermeticity was then assessed using oxidation of Cu thin discs predeposited within the sealed packages. The three intermetallic compounds AuIn2, AuIn and Au7In3 were observed. Their thickness evolution during bonding and after subsequent heat treatment was successfully modelled using a finite difference model of diffusion, thermodynamic data and diffusion coefficients calibrated from isothermal diffusion couples. 17% of the packages were hermetic and, although the origin of the leaks could not be clearly identified, it appeared that hermeticity was correlated with the unevenness of the metallisation and/or wafer and the fact that the bonds shrink due to density differences as the relative fractions of the various phases gradually evolve.
VizieR Online Data Catalog: Grid of 1D models for Mg line formation (Osorio+, 2016)
NASA Astrophysics Data System (ADS)
Osorio, Y.; Barklem, P. S.
2015-11-01
Table mgnlte.dat provides equivalent widths in LTE and non-LTE for 19 MgI spectral lines calculated in 3859 stellar atmospheres and using 21 Mg abundance per star. These data can be used to calculate abundance corrections in a broad variety of stellar models and Mg enhancements in a consistent way. The tables in data/* provides departure coefficients of the LEVEL in 10563 stellar atmospheres at 56 depth points in the atmosphere and using 21 Mg abundance values per star. These data can be used to calculate abundance corrections in a broad variety of stellar models and Mg enhancements in a consistent way. The format of the departure coefficients is the unit-less value of the ratio between the nlte and lte population of the level LEVEL of Mg. (3 data files).
NASA Astrophysics Data System (ADS)
Shubina, Maria
2016-09-01
In this paper, we investigate the one-dimensional parabolic-parabolic Patlak-Keller-Segel model of chemotaxis. For the case when the diffusion coefficient of chemical substance is equal to two, in terms of travelling wave variables the reduced system appears integrable and allows the analytical solution. We obtain the exact soliton solutions, one of which is exactly the one-soliton solution of the Korteweg-de Vries equation.
NASA Astrophysics Data System (ADS)
Kim, W.; Yum, S. S.
2015-12-01
Visibility degradation due to fog can be very hazardous both to ground transportation and aviation traffic. However, prediction of fog using numerical models is difficult because fog formation is usually determined by local meteorological conditions that are hard to be measured and modeled with sufficient resolution. For this reason, there have been several attempts to build a coupled system of a fine resolution 1D model and a 3D mesoscale model with a usual grid resolution. In this study we uses the coupled system of the 1D PAFOG model and the 3D WRF model to simulate fogs formed at a southern coastal region of Korea, where the National Center for Intensive Observation of Severe Weather (NCIO) is located. Unique to NCIO is that it has a 300 m meteorological tower on which some basic meteorological variables (temperature, dew point temperature and winds) are measured at eleven different altitudes. In addition comprehensive cloud physics measurements are made with various remote sensing instruments such as cloud radar, wind profiler, microwave radiometer, micro rain radar. Several fog cases are identified during 2015 and will be simulated by the coupled system. The comprehensive set of measurement data from NCIO will be utilized as input to the model system and for evaluating the results. Particularly the data for initial and boundary conditions, which are tightly connected to the coupled model predictability, are extracted from the tower measurement. Furthermore, various sensitivity experiments will be done to enhance our understanding of the coastal fog formation mechanism. Detailed results will be discussed at the conference.
NASA Technical Reports Server (NTRS)
Minow, Joseph I.; Coffey, Victoria N.; Parker, Linda N.; Blackwell, William C., Jr.; Jun, Insoo; Garrett, Henry B.
2007-01-01
The NUMIT 1-dimensional bulk charging model is used as a screening to ol for evaluating time-dependent bulk internal or deep dielectric) ch arging of dielectrics exposed to penetrating electron environments. T he code is modified to accept time dependent electron flux time serie s along satellite orbits for the electron environment inputs instead of using the static electron flux environment input originally used b y the code and widely adopted in bulk charging models. Application of the screening technique ts demonstrated for three cases of spacecraf t exposure within the Earth's radiation belts including a geostationa ry transfer orbit and an Earth-Moon transit trajectory for a range of orbit inclinations. Electric fields and charge densities are compute d for dielectric materials with varying electrical properties exposed to relativistic electron environments along the orbits. Our objectiv e is to demonstrate a preliminary application of the time-dependent e nvironments input to the NUMIT code for evaluating charging risks to exposed dielectrics used on spacecraft when exposed to the Earth's ra diation belts. The results demonstrate that the NUMIT electric field values in GTO orbits with multiple encounters with the Earth's radiat ion belts are consistent with previous studies of charging in GTO orb its and that potential threat conditions for electrostatic discharge exist on lunar transit trajectories depending on the electrical proper ties of the materials exposed to the radiation environment.
Study of fog characteristics by using the 1-D COBEL model at the airport of Thessaloniki, Greece
NASA Astrophysics Data System (ADS)
Stolaki, S.; Pytharoulis, I.; Karacostas, T.
2010-07-01
An attempt is made to couple the one dimensional COBEL - ISBA (COuche Brouillard Eau Liquide - Interactions Soil Biosphere Atmosphere) model with the WRF (Weather Research and Forecasting) numerical weather prediction model. This accomplishment will improve the accuracy on the short-term forecasting of fog events, which is of paramount importance -mainly to the airway companies, the airports functioning and the community as well- and will provide the means for the implementation of extensive studies of fog events formed at the "Macedonia" airport of Thessaloniki. Numerical experiments have been performed to study in depth the thermodynamic structure and the microphysical characteristics of the fog event that was formed on 06/01/2010. Moreover, the meteorological conditions -under the influence of which- the fog event was formed are also investigated. Sensitivity tests with respect to the initial conditions of temperature, relative humidity and geostrophic wind speed profiles have been performed to illustrate the model’s performance. Dew deposition rates have also been examined in order to test the importance of it on controlling the fog formation. The numerical results have been compared with actual measurements and the findings have been evaluated and discussed.
NASA Astrophysics Data System (ADS)
Harel, Marie-Alice; Mouche, Emmanuel
2015-04-01
Despite the recent research focused on runoff pattern connectivity in hydrology, there is a surprising lack of theoretical knowledge regarding hillslope runoff generation and dynamics during a rainfall event. The transient problem is especially unaddressed. In this paper we propose a model based on queueing theory formalism for the infiltration-excess overland flow generation on soils with random infiltration properties. The influence of rainfall intensity and duration on runoff dynamics and connectivity is studied thanks to this model, numerical simulation and available steady-state results. We limit our study to a rainfall intensity that is a rectangular function of time. Exact solutions for the case of spatially random exponential distributions of soil infiltrability and rainfall intensity are developed. Simulations validate these analytical results and allow for the study the rising and recession limbs of the hydrograph for different rainfall characteristics. The case of a deterministic uniform rainfall rate and different infiltrability distributions is also discussed in light of runoff connectivity. We show that the connectivity framework contributes to a better understanding and prediction of runoff pattern formation and evolution with time. A fragmented overland flow is shown to have shorter charge and discharge periods after the onset and offset of rainfall compared to well connected runoff fields. These results demonstrate that the transient regime characteristics are linked with connectivity parameters, rainstorm properties and scale issues.
Tank Tests of Model 36 Flying Boat Hull
NASA Technical Reports Server (NTRS)
Allison, John
1938-01-01
N.A.C.A. Model 36, a hull form with parallel middle body for half the length of the forebody and designed particularly for use with stub wings, was tested according to the general fixed-trim method over the range of practical loads, trims, and speeds. It was also tested free to trim with the center of gravity at two different positions. The results are given in the form of nondimensional coefficients. The resistance at the hump was exceptionally low but, at high planing speeds, afterbody interference made the performance only mediocre.
Nodal-line pairing with 1D-3D coupled Fermi surfaces: A model motivated by Cr-based superconductors
NASA Astrophysics Data System (ADS)
Wachtel, Gideon; Kim, Yong Baek
2016-09-01
Motivated by the recent discovery of a new family of chromium-based superconductors, we consider a two-band model, where a band of electrons dispersing only in one direction interacts with a band of electrons dispersing in all three directions. Strong 2 kf density fluctuations in the one-dimensional band induces attractive interactions between the three-dimensional electrons, which, in turn, makes the system superconducting. Solving the associated Eliashberg equations, we obtain a gap function which is peaked at the "poles" of the three-dimensional Fermi sphere, and decreases towards the "equator." When strong enough local repulsion is included, the gap actually changes sign around the equator and nodal rings are formed. These nodal rings manifest themselves in several experimentally observable quantities, some of which resemble unconventional observations in the newly discovered superconductors which motivated this work.
Santini, E.; Steinheimer, J.; Bleicher, M.; Schramm, S.
2011-07-15
We analyze dilepton emission from hot and dense matter using a hybrid approach based on the ultrarelativistic quantum molecular dynamics (UrQMD) transport model with an intermediate hydrodynamic stage for the description of heavy-ion collisions at relativistic energies. During the hydrodynamic stage, the production of lepton pairs is described by radiation rates for a strongly interacting medium in thermal equilibrium. In the low-mass region, hadronic thermal emission is evaluated by assuming vector meson dominance including in-medium modifications of the {rho} meson spectral function through scattering from nucleons and pions in the heat bath. In the intermediate-mass region, the hadronic rate is essentially determined by multipion annihilation processes. Emission from quark-antiquark annihilation in the quark gluon plasma (QGP) is taken into account as well. When the system is sufficiently dilute, the hydrodynamic description breaks down and a transition to a final cascade stage is performed. In this stage dimuon emission is evaluated as commonly done in transport models. By focusing on the enhancement with respect to the contribution from long-lived hadron decays after freezeout observed at the SPS in the low-mass region of the dilepton spectra, the relative importance of the different thermal contributions and of the two dynamical stages is investigated. We find that three separated regions can be identified in the invariant mass spectra. Whereas the very low and the intermediate-mass regions mostly receive contribution from the thermal dilepton emission, the region around the vector meson peak is dominated by the cascade emission. Above the {rho}-peak region the spectrum is driven by QGP radiation. Analysis of the dimuon transverse mass spectra reveals that the thermal hadronic emission shows an evident mass ordering not present in the emission from the QGP. A comparison of our calculation to recent acceptance-corrected NA60 data on invariant as well as
Wan, Jiamin; Tokunaga, Tetsu K.; Larsen, Joern T.; Zheng, Zuoping
2003-03-27
Decisions on remedial actions for leakage of highly radioactive tank waste solutions at the Hanford Site will depend highly on understanding of the current distribution and future migration of contaminants in the subsurface. The geochemical data obtained from borehole drilling at SX tank farm in the 200 Area, by Tank Farm Vadose Zone Characterization Project of the U.S. Department of Energy, revealed valuable insights as well as some results that challenge our basic understanding of waste plume evolution. In response to these needs and challenges, we have been investigating reactive transport of tank waste solutions in Hanford sediments through laboratory column experiments combined with geochemical modeling. Analyses of solid and aqueous phases within different zones of contaminant plumes, along with thermodynamic predictions provide the basis for our conceptual model. This model reveals the primary processes controlling evolution of REDOX waste plumes in the Hanford vadose zone.
Upper Stage Tank Thermodynamic Modeling Using SINDA/FLUINT
NASA Technical Reports Server (NTRS)
Schallhorn, Paul; Campbell, D. Michael; Chase, Sukhdeep; Piquero, Jorge; Fortenberry, Cindy; Li, Xiaoyi; Grob, Lisa
2006-01-01
Modeling to predict the condition of cryogenic propellants in an upper stage of a launch vehicle is necessary for mission planning and successful execution. Traditionally, this effort was performed using custom, in-house proprietary codes, limiting accessibility and application. Phenomena responsible for influencing the thermodynamic state of the propellant have been characterized as distinct events whose sequence defines a mission. These events include thermal stratification, passive thermal control roll (rotation), slosh, and engine firing. This paper demonstrates the use of an off the shelf, commercially available, thermal/fluid-network code to predict the thermodynamic state of propellant during the coast phase between engine firings, i.e. the first three of the above identified events. Results of this effort will also be presented.
Runtime and Pressurization Analyses of Propellant Tanks
NASA Technical Reports Server (NTRS)
Field, Robert E.; Ryan, Harry M.; Ahuja, Vineet; Hosangadi, Ashvin; Lee, Chung P.
2007-01-01
, shown in blue on the right-hand side of the figures, enters the tank from the diffuser at the top of the figures and impinges on the RP-1, shown in red, while the propellant is being continuously drained at the rate of 1050 lbs/sec through a pipe at the bottom of the tank. The sequence of frames in Figure 1 shows the resultant velocity fields and mixing between nitrogen and RP-1 in a cross-section of the tank at different times. A vortex is seen to form in the incoming nitrogen stream that tends to entrain propellant, mixing it with the pressurant gas. The RP-1 mass fraction contours in Figure 1 are also indicative of the level of mixing and contamination of the propellant. The simulation is used to track the propagation of the pure propellant front as it is drawn toward the exit with the evolution of the mixing processes in the tank. The CFD simulation modeled a total of 10 seconds of run time. As is seen from Figure 1d, after 5.65 seconds the propellant front is nearing the drain pipe, especially near the center of the tank. Behind this pure propellant front is a mixed fluid of compromised quality that would require the test to end when it reaches the exit pipe. Such unsteady simulations provide an estimate of the time that a high-quality propellant supply to the test article can be guaranteed at the modeled mass flow rate. In the final paper, we will discuss simulations of the LOX and propellant tanks at NASA SSC being pressurized by an inert ullage. Detailed comparisons will be made between the CFD simulations and lower order models as well as with test data. Conditions leading to cryo collapse in the tank will also be identified.
NASA Astrophysics Data System (ADS)
Laginha Silva, Patricia; Martins, Flávio A.; Boski, Tomász; Sampath, Dissanayake M. R.
2010-05-01
processes. In this viewpoint the system is broken down into its fundamental components and processes and the model is build up by selecting the important processes regardless of its time and space scale. This viewpoint was only possible to pursue in the recent years due to improvement in system knowledge and computer power (Paola, 2000). The primary aim of this paper is to demonstrate that it is possible to simulate the evolution of the sediment river bed, traditionally studied with synthetic models, with a process-based hydrodynamic, sediment transport and morphodynamic model, solving explicitly the mass and momentum conservation equations. With this objective, a comparison between two mathematical models for alluvial rivers is made to simulate the evolution of the sediment river bed of a conceptual 1D embayment for periods in the order of a thousand years: the traditional synthetic basin infilling aggregate diffusive type model based on the diffusion equation (Paola, 2000), used in the "synthesist" viewpoint and the process-based model MOHID (Miranda et al., 2000). The simulation of the sediment river bed evolution achieved by the process-based model MOHID is very similar to those obtained by the diffusive type model, but more complete due to the complexity of the process-based model. In the MOHID results it is possible to observe a more comprehensive and realistic results because this type of model include processes that is impossible to a synthetic model to describe. At last the combined effect of tide, sea level rise and river discharges was investigated in the process based model. These effects cannot be simulated using the diffusive type model. The results demonstrate the feasibility of using process based models to perform studies in scales of 10000 years. This is an advance relative to the use of synthetic models, enabling the use of variable forcing. REFERENCES • Briggs, L.I. and Pollack, H.N., 1967. Digital model of evaporate sedimentation. Science, 155, 453
1982-03-01
operational in the Bundeswehr. These include the well-known U.S. M113 APC, the HS-30 APC, developed by the Swiss company Hispano- Suiza , as well as the...powered by the Leyland L-60 engine, and the French AMX-30, powered by the Hispano- Suiza HS-110 engine. The new Japanese STB-6 tank (ඒ") is...of all foreign series-produced tank engines. A complete tank engine replacement can be performed in four hours. The Hispano- Suiza HS-110 engine
Mitochondrial dynamics changes with age in an APPsw/PS1dE9 mouse model of Alzheimer’s disease
Xu, Lin-Lin; Shen, Yang; Wang, Xiao; Wei, Li-Fei; Wang, Ping; Yang, Hui; Wang, Cun-Fu; Xie, Zhao-Hong
2017-01-01
Increasing research suggests that mitochondrial defects play a major role in Alzheimer’s disease (AD) pathogenesis. We aimed to better understand changes in mitochondria with the development and progression of AD. We compared APPsw/PS1dE9 transgenic mice at 3, 6, 9, and 12 months old as an animal model of AD and age-matched C57BL/6 mice as controls. The learning ability and spatial memory ability of APPsw/PS1dE9 mice showed significant differences compared with controls until 9 and 12 months. Mitochondrial morphology was altered in hippocampus tissue of APPsw/PS1dE9 mice beginning from the third month. ‘Medullary corpuscle’, which is formed by the accumulation of a large amount of degenerative and fragmented mitochondria in neuropils, may be the characteristic change observed on electron microscopy at a late stage of AD. Moreover, levels of mitochondrial fusion proteins (optic atrophy 1 and mitofusin 2) and fission proteins (dynamin-related protein 1 and fission 1) were altered in transgenic mice compared with controls with progression of AD. We found increased levels of fission and fusion proteins in APP/PS1 mice at 3 months, indicating that the presence of abnormal mitochondrial dynamics may be events in early AD progression. Changes in mitochondrial preceded the onset of memory decline as measured by the modified Morris water maze test. Abnormal mitochondrial dynamics could be a marker for early diagnosis of AD and monitoring disease progression. Further research is needed to study the signaling pathways that govern mitochondrial fission/fusion in AD. PMID:28118288
NASA Technical Reports Server (NTRS)
Havens, Robert F.
1946-01-01
Tests of a powered dynamic model of the Columbia XJL-1 amphibian were made in Langley tank no.1 to determine the hydrodynamic stability and spray characteristics of the basic hull and to investigate the effects of modifications on these characteristics. Modifications to the forebody chime flare, the step, and the afterbody, and an increase in the angle of incidence of the wing were included in the test program. The seaworthiness and spray characteristics were studied from simulated taxi runs in smooth and rough water. The trim limits of stability, the range of stable positions of the enter of gravity for take-off, and the landing stability were determined in smooth water. The aerodynamic lift, pitching moment, and thrust were determined at speeds up to take-off speed.
Boukazouha, F; Poulin-Vittrant, G; Tran-Huu-Hue, L P; Bavencoffe, M; Boubenider, F; Rguiti, M; Lethiecq, M
2015-07-01
This article is dedicated to the study of Piezoelectric Transformers (PTs), which offer promising solutions to the increasing need for integrated power electronics modules within autonomous systems. The advantages offered by such transformers include: immunity to electromagnetic disturbances; ease of miniaturisation for example, using conventional micro fabrication processes; and enhanced performance in terms of voltage gain and power efficiency. Central to the adequate description of such transformers is the need for complex analytical modeling tools, especially if one is attempting to include combined contributions due to (i) mechanical phenomena owing to the different propagation modes which differ at the primary and secondary sides of the PT; and (ii) electrical phenomena such as the voltage gain and power efficiency, which depend on the electrical load. The present work demonstrates an original one-dimensional (1D) analytical model, dedicated to a Rosen-type PT and simulation results are successively compared against that of a three-dimensional (3D) Finite Element Analysis (COMSOL Multiphysics software) and experimental results. The Rosen-type PT studied here is based on a single layer soft PZT (P191) with corresponding dimensions 18 mm × 3 mm × 1.5 mm, which operated at the second harmonic of 176 kHz. Detailed simulational and experimental results show that the presented 1D model predicts experimental measurements to within less than 10% error of the voltage gain at the second and third resonance frequency modes. Adjustment of the analytical model parameters is found to decrease errors relative to experimental voltage gain to within 1%, whilst a 2.5% error on the output admittance magnitude at the second resonance mode were obtained. Relying on the unique assumption of one-dimensionality, the present analytical model appears as a useful tool for Rosen-type PT design and behavior understanding.
NASA Astrophysics Data System (ADS)
Wagner, J. E.; Arola, A.; Blumthaler, M.; Fitzka, M.; Kift, R.; Kreuter, A.; Rieder, H. E.; Simic, S.; Webb, A.; Weihs, P.
2009-04-01
Since the discovery of anthropogenic ozone depletion more than 30 year ago, the scientific community has shown an increasing interest in UV-B radiation. Nowadays, ground-based high quality measurements of spectrally resolved UV-radiation are available. On the other hand, 1-D- and 3-D models have been developed, that describe the radiative transfer through the atmosphere physically very accurately. Another approach for determining the UV-irradiance at the surface of the earth is the use of satellite-based reflectance measurements as input for retrieval algorithms. At the moment, the research focuses on the impact of clouds on UV-radiation, but the impact of mountains on UV-radiation, especially in combination with high surface albedo due to snowcover, is also very strong and detailed comparisons between measurements and modelling are lacking. Therefore, three measurement campaigns had been conducted in alpine areas of Austria (Innsbruck and Hoher Sonnblick). The goal was to investigate the impact of alpine terrain in combination with snowcover on spectral UV-irradiance and actinic flux. This contribution uses the ground-based UV-irradiance measurements to evaluate three different UV-irradiance calculation methods. Results from three different calculation methods (satellite retrieval, 1-D- and 3-D radiative transfer model) for UV radiation in terms of UV-Index, erythemally weighted daily doses and spectrally resolved UV-Irradiance at 305, 310, 324 and 380nm are presented and compared with ground-based high quality measurements. The real case study is performed in very inhomogenous terrain under clear sky conditions. The values of the different methods are not only compared for the measurements sites, but additionally the impact of altitude is investigated. So far it seems, that 1-D simulations show the best agreement (±10%) with the measurements whereas the 3-D model simulations and satellite retrieved values differ much more. Satellite retrieved values
NASA Astrophysics Data System (ADS)
Turbet, Martin; Forget, Francois; Schott, Cédric
2016-10-01
The LAPS (Live Atmospheres-of-Planets Simulator) is a live 1D version of the LMD Global Climate Model that provides an accelerated and interactive simulation of the climate of terrestrial planets and exoplanets.This tool was designed for students to explore the «Classical Habitable Zone», defined as the range of orbital distances within which a planet can maintain liquid water on its surface. The model faithfully reproduces both the inner edge and the outer edge limits of the Habitable Zone, and their dependencies to the type of star and the gas composition.Furthermore, it provides a "hands on" experiment by showing how the surface and atmospheric temperatures as well as the profile of water vapor evolve through time when the external forcing (insolation, star spectrum, ...) or the planet (quantity of CO2, initial amount of water reservoir, ...) is modified.The tool is available at http://laps.lmd.jussieu.fr/ .
Kasinathan, N.; Rajakumar, A.; Vaidyanathan, G.; Chetal, S.C.
1995-09-01
Post shutdown decay heat removal is an important safety requirement in any nuclear system. In order to improve the reliability of this function, Liquid metal (sodium) cooled fast breeder reactors (LMFBR) are equipped with redundant hot pool dipped immersion coolers connected to natural draught air cooled heat exchangers through intermediate sodium circuits. During decay heat removal, flow through the core, immersion cooler primary side and in the intermediate sodium circuits are also through natural convection. In order to establish the viability and validate computer codes used in making predictions, a 1:20 scale experimental model called RAMONA with water as coolant has been built and experimental simulation of decay heat removal situation has been performed at KfK Karlsruhe. Results of two such experiments have been compiled and published as benchmarks. This paper brings out the results of the numerical simulation of one of the benchmark case through a 1D/2D coupled code system, DHDYN-1D/THYC-2D and the salient features of the comparisons. Brief description of the formulations of the codes are also included.
NAPL source zone depletion model and its application to railroad-tank-car spills.
Marruffo, Amanda; Yoon, Hongkyu; Schaeffer, David J; Barkan, Christopher P L; Saat, Mohd Rapik; Werth, Charles J
2012-01-01
We developed a new semi-analytical source zone depletion model (SZDM) for multicomponent light nonaqueous phase liquids (LNAPLs) and incorporated this into an existing screening model for estimating cleanup times for chemical spills from railroad tank cars that previously considered only single-component LNAPLs. Results from the SZDM compare favorably to those from a three-dimensional numerical model, and from another semi-analytical model that does not consider source zone depletion. The model was used to evaluate groundwater contamination and cleanup times for four complex mixtures of concern in the railroad industry. Among the petroleum hydrocarbon mixtures considered, the cleanup time of diesel fuel was much longer than E95, gasoline, and crude oil. This is mainly due to the high fraction of low solubility components in diesel fuel. The results demonstrate that the updated screening model with the newly developed SZDM is computationally efficient, and provides valuable comparisons of cleanup times that can be used in assessing the health and financial risk associated with chemical mixture spills from railroad-tank-car accidents.
Aldridge, David F.
2016-07-06
Program EMODEL_1D is an electromagnetic earth model construction utility designed to generate a three-dimensional (3D) uniformly-gridded representation of one-dimensional (1D) layered earth model. Each layer is characterized by the isotropic EM properties electric permittivity ?, magnetic permeability ?, and current conductivity ?. Moreover, individual layers of the model may possess a linear increase/decrease of any or all of these properties with depth.
Hanford Tanks 241-C-202 and 241-C-203 Residual Waste Contaminant Release Models and Supporting Data
Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Mattigod, Shas V.; Schaef, Herbert T.; Arey, Bruce W.
2007-09-13
As directed by Congress, the U. S. Department of Energy (DOE) established the Office of River Protection in 1998 to manage DOE's largest, most complex environmental cleanup project – retrieval of radioactive waste from Hanford tanks for treatment and eventual disposal. Sixty percent by volume of the nation's high-level radioactive waste is stored at Hanford in aging deteriorating tanks. If not cleaned up, this waste is a threat to the Columbia River and the Pacific Northwest. CH2M Hill Hanford Group, Inc., is the Office of River Protection's prime contractor responsible for the storage, retrieval, and disposal of Hanford's tank waste. As part of this effort, CH2M HILL Hanford Group, Inc. contracted with Pacific Northwest National Laboratory (PNNL) to develop release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for DOE.
The cumulative and sublethal effects of turbulence on erythrocytes in a stirred-tank model.
Aziz, Abdulhameed; Werner, Brian C; Epting, Kevin L; Agosti, Christopher D; Curtis, Wayne R
2007-12-01
Mechanical forces generated by prosthetic heart devices (artificial valves, artificial hearts, ventricular assist devices) have been known to cause damage and destruction of erythrocytes. Turbulent flow within such devices generates shear stresses and can induce cell damage. Current models of cell damage rate utilize only the power input per unit mass as a modeling parameter. A stirred-tank reactor provides for a more extensive characterization of turbulence through eddy scale calculations. Through a simplified model, turbulence can be characterized by evaluating the Kolmogorov microscale. Our analysis of erythrocyte rupture in a stirred tank reactor suggests that parameters such as eddy wavelength and eddy velocity may better characterize and model the turbulent damage. Further, hemolysis of red blood cells by turbulent effects has been shown to have a fixed rate for constant levels of power input. Damage inflicted on the remaining, intact erythrocytes (sublethal damage) was evaluated by exposure to turbulence followed by osmotic fragility (OF) testing. Logistic models were fit to the OF data indicating a significant osmotic sensitivity in the sublethal damaged population between control and turbulence-exposed cells (chi(2) test; p < 0.001). This susceptibility indicates a significant cell population more susceptible to destruction as a result of turbulent exposure. This work has therefore helped identify optimization parameters for evaluating cell damage potential when engineering cardiovascular prosthetic devices.
NASA Technical Reports Server (NTRS)
Sasmal, G. P.; Hochstein, J. I.; Wendl, M. C.; Hardy, T. L.
1991-01-01
A multidimensional computational model of the pressurization process in a slush hydrogen propellant storage tank was developed and its accuracy evaluated by comparison to experimental data measured for a 5 ft diameter spherical tank. The fluid mechanic, thermodynamic, and heat transfer processes within the ullage are represented by a finite-volume model. The model was shown to be in reasonable agreement with the experiment data. A parameter study was undertaken to examine the dependence of the pressurization process on initial ullage temperature distribution and pressurant mass flow rate. It is shown that for a given heat flux rate at the ullage boundary, the pressurization process is nearly independent of initial temperature distribution. Significant differences were identified between the ullage temperature and velocity fields predicted for pressurization of slush and those predicted for pressurization of liquid hydrogen. A simplified model of the pressurization process was constructed in search of a dimensionless characterization of the pressurization process. It is shown that the relationship derived from this simplified model collapses all of the pressure history data generated during this study into a single curve.
Tank Tests of Models of Flying Boat Hulls Having Longitudinal Steps
NASA Technical Reports Server (NTRS)
Allison, John M; Ward, Kenneth E
1936-01-01
Four models with longitudinal steps on the forebody were developed by modification of a model of a conventional hull and were tested in the National Advisory Committee for Aeronautics (NACA) tank. Models with longitudinal steps were found to have smaller resistance at high speed and greater resistance at low speed than the parent model that had the same afterbody but a conventional V-section forebody. The models with a single longitudinal step had better performance at hump speed and as low high-speed resistance except at very light loads. Spray strips at angles from 0 degrees to 45 degrees to the horizontal were fitted at the longitudinal steps and at the chine on one of the two step models having two longitudinal steps. The resistance and the height of the spray were less with each of the spray strips than without; the most favorable angle was found to lie between 15 degrees and 30 degrees.
NASA Astrophysics Data System (ADS)
Hurlbatt, A.; O'Connell, D.; Gans, T.
2016-08-01
Analytical and numerical models allow investigation of complicated discharge phenomena and the interplay that makes plasmas such a complex environment. Global models are quick to implement and can have almost negligible computation cost, but provide only bulk or spatially averaged values. Full fluid models take longer to develop, and can take days to solve, but provide accurate spatio-temporal profiles of the whole plasma. The work presented here details a different type of model, analytically similar to fluid models, but computationally closer to a global model, and able to give spatially resolved solutions for the challenging environment of electronegative plasmas. Included are non-isothermal electrons, gas heating, and coupled neutral dynamics. Solutions are reached in seconds to minutes, and spatial profiles are given for densities, fluxes, and temperatures. This allows the semi-analytical model to fill the gap that exists between global and full fluid models, extending the tools available to researchers. The semi-analytical model can perform broad parameter sweeps that are not practical with more computationally expensive models, as well as exposing non-trivial trends that global models cannot capture. Examples are given for a low pressure oxygen CCP. Excellent agreement is shown with a full fluid model, and comparisons are drawn with the corresponding global model.
Finite elements model of a rotating half-bridge belonging to a circular settling tank
NASA Astrophysics Data System (ADS)
Dascalescu, A. E.; Lazaroiu, G.; Scupi, A. A.; Oanta, E.
2016-08-01
A circular settling tank is an open reservoir used for the gravitational separation of the sludge and of the clarified water which is discharged in the launder which is mounted at the periphery of the basin. The extraction of the sludge is done by the use of a rotating half-bridge which sweeps the sludge, vacuums it using a system of scrapping blades and suction pipes, collects it in some local sludge chambers and pour it in a central collecting tank. The rotating half-bridge is a complex structure under a complex system of loads, therefore advanced instruments of investigation are required to assess the state of strains and stresses in this structure. Until now an analytical model was developed based on the hypotheses specific to the strength of materials academic discipline. The numerical models presented in the paper use the finite element method to determine the displacements of the main beam loaded by the weight of the structure and by the Archimedes’ forces. The results of the models developed so far are conclusive for the future directions of research which aims a higher degree of accuracy of the models and of the according research methodology.
Unit cell modeling in support of interim performance assessment for low level tank waste disposal
Kline, N.W., Westinghouse Hanford
1996-08-01
A unit cell model is used to simulate the base analysis case and related sensitivity cases for the interim performance assessment of low level tank waste disposal. Simulation case results are summarized in terms of fractional contaminant release rates to the vadose zone and to the water table at the unconfined aquifer. Results suggest that the crushed glass water conditioning layer at the top of the facility and the chemical retardation pad at the bottom of the facility can be important components of the facility. Results also suggest that the release rates to the water table are dominated by the release rate from the waste form.
Hanford Site Tank 241-C-108 Residual Waste Contaminant Release Models and Supporting Data
Cantrell, Kirk J.; Krupka, Kenneth M.; Geiszler, Keith N.; Arey, Bruce W.; Schaef, Herbert T.
2010-06-18
This report presents the results of laboratory characterization, testing, and analysis for a composite sample (designated 20578) of residual waste collected from single-shell tank C-108 during the waste retrieval process after modified sluicing. These studies were completed to characterize concentration and form of contaminant of interest in the residual waste; assess the leachability of contaminants from the solids; and develop release models for contaminants of interest. Because modified sluicing did not achieve 99% removal of the waste, it is expected that additional retrieval processing will take place. As a result, the sample analyzed here is not expected to represent final retrieval sample.
Three-dimensional vector modeling and restoration of flat finite wave tank radiometric measurements
NASA Technical Reports Server (NTRS)
Truman, W. M.; Balanis, C. A.
1977-01-01
The three-dimensional vector interaction between a microwave radiometer and a wave tank was modeled. Computer programs for predicting the response of the radiometer to the brightness temperature characteristics of the surroundings were developed along with a computer program that can invert (restore) the radiometer measurements. It is shown that the computer programs can be used to simulate the viewing of large bodies of water, and is applicable to radiometer measurements received from satellites monitoring the ocean. The water temperature, salinity, and wind speed can be determined.
Development of a Thermodynamic Model for the Hanford Tank Waste Operations Simulator - 12193
Carter, Robert; Seniow, Kendra
2012-07-01
The Hanford Tank Waste Operations Simulator (HTWOS) is the current tool used by the Hanford Tank Operations Contractor for system planning and assessment of different operational strategies. Activities such as waste retrievals in the Hanford tank farms and washing and leaching of waste in the Waste Treatment and Immobilization Plant (WTP) are currently modeled in HTWOS. To predict phase compositions during these activities, HTWOS currently uses simple wash and leach factors that were developed many years ago. To improve these predictions, a rigorous thermodynamic framework has been developed based on the multi-component Pitzer ion interaction model for use with several important chemical species in Hanford tank waste. These chemical species are those with the greatest impact on high-level waste glass production in the WTP and whose solubility depends on the processing conditions. Starting with Pitzer parameter coefficients and species chemical potential coefficients collated from open literature sources, reconciliation with published experimental data led to a self-consistent set of coefficients known as the HTWOS Pitzer database. Using Gibbs energy minimization with the Pitzer ion interaction equations in Microsoft Excel,1 a number of successful predictions were made for the solubility of simple mixtures of the chosen species. Currently, this thermodynamic framework is being programmed into HTWOS as the mechanism for determining the solid-liquid phase distributions for the chosen species, replacing their simple wash and leach factors. Starting from a variety of open literature sources, a collection of Pitzer parameters and species chemical potentials, as functions of temperature, was tested for consistency and accuracy by comparison with available experimental thermodynamic data (e.g., osmotic coefficients and solubility). Reconciliation of the initial set of parameter coefficients with the experimental data led to the development of the self-consistent set known
NASA Astrophysics Data System (ADS)
Persson, O. P.; Solomon, A.
2013-12-01
Though leads only represent a small portion of the Arctic sea-ice area, their contribution to the surface turbulent energy and momentum fluxes can be significant. Numerous modeling studies presented in the literature have been conducted examining these effects. The results of such studies have indicated the importance of the environmental large-scale stability, the environmental humidity, the lead width, the ice (lead) concentration, the lead size distribution, the character of the leads (open water, refrozen), etc. Because global climate models (GCMs) show significant sensitivity to the large-scale net energy flux from the heterogeneous sea-ice surface, and because thinner ice in the projected future Arctic climate will likely result in increasing lead fractions, the appropriate GCM representation of this complex system is important. This study presents modeling results based on observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment, for which the mid-winter sea-ice was greatly heterogeneous. In mid-January, the 100x100 km region surrounding the SHEBA ice camp consisted of a lead fraction of ~16-33% as revealed by SAR data. This included primarily older refrozen lead areas that were generated at least a month earlier (~16-25% areal coverage), with a smaller fraction of newly opened leads (~4-9% areal coverage). Utilizing the sequence of SAR images, the atmospheric observations at the SHEBA site, and a 1-D snow and ice model, the spatial distribution of sea-ice thickness, snow depth, and surface temperatures within this domain were estimated over a 6-week period, revealing the significant impact of leads in all stages on GCM-scale temperatures and fluxes. This combined observational/model data series is used to evaluate a variety of one-dimensional turbulent flux aggregation techniques (e.g., mosaic) that use different assumptions. Furthermore, by using the spatial distribution of these surface characteristics, three-dimensional large eddy
COSTING MODELS FOR WATER SUPPLY DISTRIBUTION: PART III- PUMPS, TANKS, AND RESERVOIRS
Distribution systems are generally designed to ensure hydraulic reliability. Storage tanks, reservoirs and pumps are critical in maintaining this reliability. Although storage tanks, reservoirs and pumps are necessary for maintaining adequate pressure, they may also have a negati...
RAST RS; RINKER MW; BAPANAALLI SK; DEIBLER JE; GUZMAN-LEONG CE; JOHNSON KI; KARRI NK; PILLI SP; SANBORN SE
2010-10-22
This document is a Phase I deliverable for the Single-Shell Tank Analysis of Record effort. This document is not the Analysis of Record. The intent of this document is to guide the Phase II detailed modeling effort. Preliminary finite element models for each of the tank types were developed and different case studies were performed on one or more of these tank types. Case studies evaluated include thermal loading, waste level variation, the sensitivity of boundary effects (soil radial extent), excavation slope or run to rise ratio, soil stratigraphic (property and layer thickness) variation at different farm locations, and concrete material property variation and their degradation under thermal loads. The preliminary analysis document reviews and preliminary modeling analysis results are reported herein. In addition, this report provides recommendations for the next phase of the SST AOR project, SST detailed modeling. Efforts and results discussed in this report do not include seismic modeling as seismic modeling is covered by a separate report. The combined results of both static and seismic models are required to complete this effort. The SST AOR project supports the US Department of Energy's (DOE) Office of River Protection (ORP) mission for obtaining a better understanding of the structural integrity of Hanford's SSTs. The 149 SSTs, with six different geometries, have experienced a range of operating histories which would require a large number of unique analyses to fully characterize their individual structural integrity. Preliminary modeling evaluations were conducted to determine the number of analyses required for adequate bounding of each of the SST tank types in the Detailed Modeling Phase of the SST AOR Project. The preliminary modeling was conducted in conjunction with the Evaluation Criteria report, Johnson et al. (2010). Reviews of existing documents were conducted at the initial stage of preliminary modeling. These reviews guided the topics that were
Modeling Ullage Dynamics of Tank Pressure Control Experiment during Jet Mixing in Microgravity
NASA Technical Reports Server (NTRS)
Kartuzova, O.; Kassemi, M.
2016-01-01
A CFD model for simulating the fluid dynamics of the jet induced mixing process is utilized in this paper to model the pressure control portion of the Tank Pressure Control Experiment (TPCE) in microgravity1. The Volume of Fluid (VOF) method is used for modeling the dynamics of the interface during mixing. The simulations were performed at a range of jet Weber numbers from non-penetrating to fully penetrating. Two different initial ullage positions were considered. The computational results for the jet-ullage interaction are compared with still images from the video of the experiment. A qualitative comparison shows that the CFD model was able to capture the main features of the interfacial dynamics, as well as the jet penetration of the ullage.
An analytical probabilistic model of the quality efficiency of a sewer tank
NASA Astrophysics Data System (ADS)
Balistrocchi, Matteo; Grossi, Giovanna; Bacchi, Baldassare
2009-12-01
The assessment of the efficiency of a storm water storage facility devoted to the sewer overflow control in urban areas strictly depends on the ability to model the main features of the rainfall-runoff routing process and the related wet weather pollution delivery. In this paper the possibility of applying the analytical probabilistic approach for developing a tank design method, whose potentials are similar to the continuous simulations, is proved. In the model derivation the quality issues of such devices were implemented. The formulation is based on a Weibull probabilistic model of the main characteristics of the rainfall process and on a power law describing the relationship between the dimensionless storm water cumulative runoff volume and the dimensionless cumulative pollutograph. Following this approach, efficiency indexes were established. The proposed model was verified by comparing its results to those obtained by continuous simulations; satisfactory agreement is shown for the proposed efficiency indexes.
NASA Astrophysics Data System (ADS)
Brown, A.; Dahlke, H. E.
2015-12-01
The ability of soil to infiltrate large volumes of water is fundamental to managed aquifer recharge (MAR) when using infiltration basins or agricultural fields. In order to investigate the feasibility of using agricultural fields for MAR we conducted a field experiment designed to not only assess the resilience of alfalfa (Medicago sativa) to large (300 mm), short duration (1.5 hour), repeated irrigation events during the winter but also how crop resilience was influenced by soil water movement. We hypothesized that large irrigation amounts designed for groundwater recharge could cause prolonged saturated conditions in the root-zone and yield loss. Tensiometers were installed at two depths (60 and 150 cm) in a loam soil to monitor the changes in soil matric potential within and below the root-zone following irrigation events in each of five experimental plots (8 x 16 m2). To simulate the individual infiltration events we employed the HYDRUS-1D computational module (Simunek et al., 2005) and compared the finite-water content vadose zone flow method (Ogden et al. 2015) with numerical solutions to the Richards' equation. For both models we assumed a homogenous and isotropic root zone that is initially unsaturated with no water flow. Here we assess the ability of these two models to account for the control volume applied to the plots and to capture sharp changes in matric potential that were observed in the early time after an irrigation pulse. The goodness-of-fit of the models was evaluated using the root mean square error (RMSE) for observed and predicted values of cumulative infiltration over time, wetting front depth over time and water content at observation nodes. For the finite-water content method, the RMSE values and output for observation nodes were similar to that from the HYDRUS-1D solution. This indicates that the finite-water content method may be useful for predicting the fate of large volumes of water applied for MAR. Moreover, both models suggest a
NASA Astrophysics Data System (ADS)
Kristensen, Tom; Simoni, Andrea; Launay, Jean-Michel
2016-05-01
We compute scattering and bound state properties for two ultracold molecules in a pure 1D optical lattice. We introduce reference functions with complex quasi-momentum that naturally account for the effect of excited energy bands. Our exact results for a short-range interaction are first compared with the simplest version of the standard Bose-Hubbard (BH) model. Such comparison allows us to highlight the effect of the excited bands, of the non-on-site interaction and of tunneling with distant neighbor, that are not taken into account in the BH model. The effective interaction can depend strongly on the particle quasi-momenta and can present a resonant behavior even in a deep lattice. As a second step, we study scattering of two polar particles in the optical lattice. Peculiar Wigner threshold laws stem from the interplay of the long range dipolar interaction and the presence of the energy bands. We finally assess the validity of an extended Bose-Hubbard model for dipolar gases based on our exact two-body calculations. This work was supported by the Agence Nationale de la Recherche (Contract No. ANR-12-BS04-0020-01).
Mellott, Tiffany J.; Huleatt, Olivia M.; Shade, Bethany N.; Pender, Sarah M.; Liu, Yi B.; Slack, Barbara E.; Blusztajn, Jan K.
2017-01-01
Prevention of Alzheimer's disease (AD) is a major goal of biomedical sciences. In previous studies we showed that high intake of the essential nutrient, choline, during gestation prevented age-related memory decline in a rat model. In this study we investigated the effects of a similar treatment on AD-related phenotypes in a mouse model of AD. We crossed wild type (WT) female mice with hemizygous APPswe/PS1dE9 (APP.PS1) AD model male mice and maintained the pregnant and lactating dams on a control AIN76A diet containing 1.1 g/kg of choline or a choline-supplemented (5 g/kg) diet. After weaning all offspring consumed the control diet. As compared to APP.PS1 mice reared on the control diet, the hippocampus of the perinatally choline-supplemented APP.PS1 mice exhibited: 1) altered levels of amyloid precursor protein (APP) metabolites–specifically elevated amounts of β-C-terminal fragment (β-CTF) and reduced levels of solubilized amyloid Aβ40 and Aβ42 peptides; 2) reduced number and total area of amyloid plaques; 3) preserved levels of choline acetyltransferase protein (CHAT) and insulin-like growth factor II (IGF2) and 4) absence of astrogliosis. The data suggest that dietary supplementation of choline during fetal development and early postnatal life may constitute a preventive strategy for AD. PMID:28103298
NASA Astrophysics Data System (ADS)
Delettrez, J. A.; Myatt, J. F.; Yaakobi, B.
2015-11-01
The modeling of the fast-electron transport in the 1-D hydrodynamic code LILAC was modified because of the addition of cross-beam-energy-transfer (CBET) in implosion simulations. Using the old fast-electron with source model CBET results in a shift of the peak of the hard x-ray (HXR) production from the end of the laser pulse, as observed in experiments, to earlier in the pulse. This is caused by a drop in the laser intensity of the quarter-critical surface from CBET interaction at lower densities. Data from simulations with the laser plasma simulation environment (LPSE) code will be used to modify the source algorithm in LILAC. In addition, the transport model in LILAC has been modified to include deviations from the straight-line algorithm and non-specular reflection at the sheath to take into account the scattering from collisions and magnetic fields in the corona. Simulation results will be compared with HXR emissions from both room-temperature plastic and cryogenic target experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Modeling and Processing of Terahertz Imaging in Space Shuttle External Tank Foam Inspection
NASA Astrophysics Data System (ADS)
Chiou, Chien-Ping; Thompson, R. Bruce; Winfree, William P.; Madaras, Eric I.; Seebo, Jeffrey
2006-03-01
Recently, terahertz ray (T-ray) imaging emerged as one of the most promising techniques to inspect the space shuttle external tank foam insulation. This paper demonstrates the application of state-of-the-art computer processing and modeling technologies to assist in further refinement of this new technology. The current protocol of T-ray inspection and its limitations are first reviewed. New strategies of using signal processing and modeling are then proposed to improve on the flaw detection. Preliminary results are presented on a series of multi-dimensional signal processing operations of T-ray signals. The use of models and their comparisons with experimental data from foam samples are also included.
Semi-analytical models of hydroelastic sloshing impact in tanks of liquefied natural gas vessels.
Ten, I; Malenica, Š; Korobkin, A
2011-07-28
The present paper deals with the methods for the evaluation of the hydroelastic interactions that appear during the violent sloshing impacts inside the tanks of liquefied natural gas carriers. The complexity of both the fluid flow and the structural behaviour (containment system and ship structure) does not allow for a fully consistent direct approach according to the present state of the art. Several simplifications are thus necessary in order to isolate the most dominant physical aspects and to treat them properly. In this paper, choice was made of semi-analytical modelling for the hydrodynamic part and finite-element modelling for the structural part. Depending on the impact type, different hydrodynamic models are proposed, and the basic principles of hydroelastic coupling are clearly described and validated with respect to the accuracy and convergence of the numerical results.
NASA Astrophysics Data System (ADS)
Borbon, A.; Ruiz, M.; Bechara, J.; Afif, C.; Huntrieser, H.; Mills, G.; Mari, C.; Reeves, C.; Schlager, H.
2010-12-01
Deep convection plays a key role in determining global atmospheric composition of the upper troposphere by the fast uplift of HOx radical and ozone precursors to the upper troposphere. Formaldehyde (HCHO) is one important gas precursor. It is the most abundant carbonyl compound originating from both primary processes and photooxidation of volatile organic compounds. Thus, determining its source strength to the upper troposphere is important for estimating ozone production. However processes governing its fate are multiple and complex including dynamics (entrainment and detrainment), multiphase chemistry and cloud microphysics. As a result, the flux of formaldehyde to the upper troposphere is still uncertain. The goal of this study is to examine the redistribution of formaldehyde in tropical mesoscale convective systems (MSC) and to estimate its sources and sinks during convective transport to the upper troposphere. The novelty here is to combine 1D modelling (Meso NH model) and formaldehyde aircraft observations. Observations were collected over West Africa during the monsoon period (July-August 2006) of the AMMA experiment. Four aircrafts (English BAe-146, French ATR-42 and Falcon-20 and German Falcon-20) were deployed over a large domain (long.: -8°E-5°W, lat. 4°N-20°N, alt.: 0 12 km) with formaldehyde measuring instruments on board. First, this presentation will point out the construction of a comprehensive and consistent data set of formaldehyde by ensuring data comparability thanks to aircraft intercomparison flights, multiple chemical tracer approach (CO, O3 and relative humidity) and a spatial gridding of the domain. Then formaldehyde spatial variability will be examined under background and convective conditions. Finally, the relative importance of transport (entrainment) and wet scavenging will be discussed from selected AMMA flights. For that purpose, the following equation system has been resolved [HCHO]transported to UT=[HCHO]measured - [HCHO
Hanford Tanks 241-C-203 and 241-C-204: Residual Waste Contaminant Release Model and Supporting Data
Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.
2004-10-28
This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for the U.S. Department of Energy.
Hanford Tanks 241-C-203 and 241 C 204: Residual Waste Contaminant Release Model and Supporting Data
Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.
2007-05-23
This report was revised in May 2007 to correct 90Sr values in Chapter 3. The changes were made on page 3.9, paragraph two and Table 3.10; page 3.16, last paragraph on the page; and Tables 3.21 and 3.31. The rest of the text remains unchanged from the original report issued in October 2004. This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for the U.S. Department of Energy.
NASA Astrophysics Data System (ADS)
Bryan, Alexander M.; Cheng, Susan J.; Ashworth, Kirsti; Guenther, Alex B.; Hardiman, Brady S.; Bohrer, Gil; Steiner, Allison L.
2015-11-01
Foliar emissions of biogenic volatile organic compounds (BVOC)-important precursors of tropospheric ozone and secondary organic aerosols-vary widely by vegetation type. Modeling studies to date typically represent the canopy as a single dominant tree type or a blend of tree types, yet many forests are diverse with trees of varying height. To assess the sensitivity of biogenic emissions to tree height variation, we compare two 1-D canopy model simulations in which BVOC emission potentials are homogeneous or heterogeneous with canopy depth. The heterogeneous canopy emulates the mid-successional forest at the University of Michigan Biological Station (UMBS). In this case, high-isoprene-emitting foliage (e.g., aspen and oak) is constrained to the upper canopy, where higher sunlight availability increases the light-dependent isoprene emission, leading to 34% more isoprene and its oxidation products as compared to the homogeneous simulation. Isoprene declines from aspen mortality are 10% larger when heterogeneity is considered. Overall, our results highlight the importance of adequately representing complexities of forest canopy structure when simulating light-dependent BVOC emissions and chemistry.
Bryan, Alexander M.; Cheng, Susan J.; Ashworth, Kirsti; Guenther, Alex B.; Hardiman, Brady; Bohrer, Gil; Steiner, A. L.
2015-11-01
Foliar emissions of biogenic volatile organic compounds (BVOC)dimportant precursors of tropospheric ozone and secondary organic aerosolsdvary widely by vegetation type. Modeling studies to date typi-cally represent the canopy as a single dominant tree type or a blend of tree types, yet many forests are diverse with trees of varying height. To assess the sensitivity of biogenic emissions to tree height vari-ation, we compare two 1-D canopy model simulations in which BVOC emission potentials are homo-geneous or heterogeneous with canopy depth. The heterogeneous canopy emulates the mid-successional forest at the University of Michigan Biological Station (UMBS). In this case, high-isoprene-emitting fo-liage (e.g., aspen and oak) is constrained to the upper canopy, where higher sunlight availability increases the light-dependent isoprene emission, leading to 34% more isoprene and its oxidation products as compared to the homogeneous simulation. Isoprene declines from aspen mortality are 10% larger when heterogeneity is considered. Overall, our results highlight the importance of adequately representing complexities of forest canopy structure when simulating light-dependent BVOC emissions and chemistry.
Tank Tests of a Model of the NC Flying-boat Hull - N.A.C.A. Model 44
NASA Technical Reports Server (NTRS)
Bell, Joe W
1936-01-01
A 1/7.06 full-size model of the NC-type hull was tested in the N.A.C.A. tank by both the general method and the specific or free-to-trim method. The results of the tests are given in curves plotted as non dimensional coefficients and are compared with the test results of N.A.C.A. model 11-A. The NC model (N.A.C.A. model 44) shows higher resistance than model 11-A at hump speed but lower resistance at high speeds. Model 44 has a higher best trim angle at the jump and a lower maximum positive trimming moment than model 11-A. At high speeds the best trim angle and the trimming moments of the two models are approximately the same.
Iwamoto, Masami; Nakahira, Yuko
2015-11-01
Accurate prediction of occupant head kinematics is critical for better understanding of head/face injury mechanisms in side impacts, especially far-side occupants. In light of the fact that researchers have demonstrated that muscle activations, especially in neck muscles, can affect occupant head kinematics, a human body finite element (FE) model that considers muscle activation is useful for predicting occupant head kinematics in real-world automotive accidents. In this study, we developed a human body FE model called the THUMS (Total HUman Model for Safety) Version 5 that contains 262 one-dimensional (1D) Hill-type muscle models over the entire body. The THUMS was validated against 36 series of PMHS (Post Mortem Human Surrogate) and volunteer test data in this study, and 16 series of PMHS and volunteer test data on side impacts are presented. Validation results with force-time curves were also evaluated quantitatively using the CORA (CORrelation and Analysis) method. The validation results suggest that the THUMS has good biofidelity in the responses of the regional or full body for side impacts, but relatively poor biofidelity in its local level of responses such as brain displacements. Occupant kinematics predicted by the THUMS with a muscle controller using 22 PID (Proportional-Integral- Derivative) controllers were compared with those of volunteer test data on low-speed lateral impacts. The THUMS with muscle controller reproduced the head kinematics of the volunteer data more accurately than that without muscle activation, although further studies on validation of torso kinematics are needed for more accurate predictions of occupant head kinematics.
Tank Investigation of the EDO Model 142 Hydro-Ski Research Airplane
NASA Technical Reports Server (NTRS)
Ramsen, John A.; Wadlin, Kenneth L.; Gray, George R.
1951-01-01
A tank investigation has been conducted of a 1/10-size powered-dynamic model of the Edo model 142 hydra-ski research airplane. The results of tests of two configurations are presented: One included a large ski and a ski well; the other, a small ski without a well. Water take-offs would be possible with the available thrust for either configuration: however, the configuration with the large ski emerged sooner and had less resistance from ski emergence until take-off. Longitudinal stability and landing behavior in smooth water were satisfactory for both configurations. Some alteration to the design of the tail would be desirable in order to reduce the spray loads.
Simulation of Fault Arc Based on Different Radiation Models in a Closed Tank
NASA Astrophysics Data System (ADS)
Li, Mei; Zhang, Junpeng; Hu, Yang; Zhang, Hantian; Wu, Yifei
2016-05-01
This paper focuses on the simulation of a fault arc in a closed tank based on the magneto-hydrodynamic (MHD) method, in which a comparative study of three radiation models, including net emission coefficients (NEC), semi-empirical model based on NEC as well as the P1 model, is developed. The pressure rise calculated by the three radiation models are compared to the measured results. Particularly when the semi-empirical model is used, the effect of different boundary temperatures of the re-absorption layer in the semi-empirical model on pressure rise is concentrated on. The results show that the re-absorption effect in the low-temperature region affects radiation transfer of fault arcs evidently, and thus the internal pressure rise. Compared with the NEC model, P1 and the semi-empirical model with 0.7<α<0.83 are more suitable to calculate the pressure rise of the fault arc, where is an adjusted parameter involving the boundary temperature of the re-absorption region in the semi-empirical model. supported by National Key Basic Research Program of China (973 Program) (No. 2015CB251002), National Natural Science Foundation of China (Nos. 51221005, 51177124), the Fundamental Research Funds for the Central Universities, the Program for New Century Excellent Talents in University and Shaanxi Province Natural Science Foundation of China (No. 2013JM-7010)
NASA Astrophysics Data System (ADS)
Lea, J. M.; Mair, D.; Nick, F. M.; Rea, B. R.; Schofield, E.; Nienow, P. W.
2012-12-01
The ability to successfully model the behaviour of Greenlandic tidewater glaciers is pivotal for the prediction of future behaviour and potential impact on global sea level. However, to have confidence in the results of numerical models, they must be capable of replicating the full range of observed glacier behaviour (i.e. both advance and retreat) when realistic forcings are applied. Due to the paucity of observational records recording this behaviour, it is therefore necessary to verify calving models against reconstructions of glacier dynamics. The dynamics of Kangiata Nunaata Sermia (KNS) can be reconstructed with a high degree of detail using a combination of sedimentological and geomorphological evidence, photographs, historical sources and satellite imagery. Since the LIA-maximum KNS has retreated a total of 21 km with multiple phases of rapid retreat evident between topographic pinning points. A readvance attaining a position 9 km from the current terminus associated with the '1920 stade' is also identified. KNS therefore represents an ideal test location for calving models since it has both advanced and retreated over known timescales, while the scale of fluctuations implies KNS is sensitive to parameter(s) controlling terminus stability. Using the known stable positions for verification, we present the results of an array of sensitivity tests conducted on KNS using the 1-D flowband calving model of Nick et al (2009). The model is initially tuned to an historically stable position where the glacier configuration is accurately known (in this case 1985), and forced by varying surface mass balance, crevasse water depth, submarine melt rate at the calving front, in addition to the strength and pervasiveness of sikussak in the fjord. Successive series of experiments were run using each parameter to test model sensitivity to the initial conditions of each variable. Results indicate that the model is capable of stabilising at locations that are in agreement with
NASA Technical Reports Server (NTRS)
Dobson, Chris C.; Hrbud, Ivana
2004-01-01
Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the 1-D Poisson equation for EC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with non-fusing hydrogen-1. The deuterium rates are consistent with predictions from the model.
NASA Astrophysics Data System (ADS)
Zhong, H.; van Overloop, P.-J.; van Gelder, P. H. A. J. M.
2013-07-01
The Lower Rhine Delta, a transitional area between the River Rhine and Meuse and the North Sea, is at risk of flooding induced by infrequent events of a storm surge or upstream flooding, or by more infrequent events of a combination of both. A joint probability analysis of the astronomical tide, the wind induced storm surge, the Rhine flow and the Meuse flow at the boundaries is established in order to produce the joint probability distribution of potential flood events. Three individual joint probability distributions are established corresponding to three potential flooding causes: storm surges and normal Rhine discharges, normal sea levels and high Rhine discharges, and storm surges and high Rhine discharges. For each category, its corresponding joint probability distribution is applied, in order to stochastically simulate a large number of scenarios. These scenarios can be used as inputs to a deterministic 1-D hydrodynamic model in order to estimate the high water level frequency curves at the transitional locations. The results present the exceedance probability of the present design water level for the economically important cities of Rotterdam and Dordrecht. The calculated exceedance probability is evaluated and compared to the governmental norm. Moreover, the impact of climate change on the high water level frequency curves is quantified for the year 2050 in order to assist in decisions regarding the adaptation of the operational water management system and the flood defense system.
NASA Astrophysics Data System (ADS)
Dascalescu, A. E.; Lazaroiu, G.; Scupi, A. A.; Oanta, E.
2016-08-01
The rotating half-bridge of a settling tank is employed to sweep the sludge from the wastewater and to vacuum and sent it to the central collector. It has a complex geometry but the main beam may be considered a slender bar loaded by the following category of forces: concentrated forces produced by the weight of the scrapping system of blades, suction pipes, local sludge collecting chamber, plus the sludge in the horizontal sludge transporting pipes; forces produced by the access bridge; buoyant forces produced by the floating barrels according to Archimedes’ principle; distributed forces produced by the weight of the main bridge; hydrodynamic forces. In order to evaluate the hydrodynamic loads we have conceived a numerical model based on the finite volume method, using the ANSYS-Fluent software. To model the flow we used the equations of Reynolds Averaged Navier-Stokes (RANS) for liquids together with Volume of Fluid model (VOF) for multiphase flows. For turbulent model k-epsilon we used the equation for turbulent kinetic energy k and dissipation epsilon. These results will be used to increase the accuracy of the loads’ sub-model in the theoretical models, e. the finite element model and the analytical model.
Ribes, J; Ferrer, J; Bouzas, A; Seco, A
2002-10-01
A complete model of a primary settler including both sedimentation and biological processes is presented. It is a one-dimensional model based on the solids flux concept and the conservation of mass that uses the Takács model for the settling velocity, which is corrected by a compression function in the lower layers. The biological model is based on the ASM2 and enlarged with the fermentation model proposed by this research group. The settler was split in ten layers and the flux terms in the mass balance for each layer is obtained by means of the settling model. A pilot plant has been operated to study the primary sludge fermentation and volatile fatty acids (VFA) elutriation in a primary settler tank. The model has been tested with pilot plant experimental data with very good results. It has been able to simulate the VFA production in the settler and their elutriation with the influent wastewater for all the studied experiments. The developed model is easily applicable to secondary settlers and thickeners, also taking into account biological activity inside them.
NASA Astrophysics Data System (ADS)
Bozza, Andrea; Durand, Arnaud; Allenbach, Bernard; Confortola, Gabriele; Bocchiola, Daniele
2013-04-01
We present a feasibility study to explore potential of high-resolution imagery, coupled with hydraulic flood modeling to predict flooding risks, applied to the case study of Gonaives basins (585 km²), Haiti. We propose a methodology working at different scales, providing accurate results and a faster intervention during extreme flood events. The 'Hispaniola' island, in the Caribbean tropical zone, is often affected by extreme floods events. Floods are caused by tropical springs and hurricanes, and may lead to several damages, including cholera epidemics, as recently occurred, in the wake of the earthquake upon January 12th 2010 (magnitude 7.0). Floods studies based upon hydrological and hydraulic modeling are hampered by almost complete lack of ground data. Thenceforth, and given the noticeable cost involved in the organization of field measurement campaigns, the need for exploitation of remote sensing images data. HEC-RAS 1D modeling is carried out under different scenarios of available Digital Elevation Models. The DEMs are generated using optical remote sensing satellite (WorldView-1) and SRTM, combined with information from an open source database (Open Street Map). We study two recent flood episodes, where flood maps from remote sensing were available. Flood extent and land use have been assessed by way of data from SPOT-5 satellite, after hurricane Jeanne in 2004 and hurricane Hanna in 2008. A semi-distributed, DEM based hydrological model is used to simulate flood flows during the hurricanes. Precipitation input is taken from daily rainfall data derived from TRMM satellite, plus proper downscaling. The hydraulic model is calibrated using floodplain friction as tuning parameters against the observed flooded area. We compare different scenarios of flood simulation, and the predictive power of model calibration. The method provide acceptable results in depicting flooded areas, especially considering the tremendous lack of ground data, and show the potential of
Modeling of Slosh Dynamics in Cryogenic Propellant Tanks in Microgravity Environments
NASA Technical Reports Server (NTRS)
2008-01-01
The slosh dynamics in cryogenic fuel tanks under microgravity is a pressing problem that severely affects the reliability of launching spacecraft. After reaching low Earth orbit, the propellant in a multistage rocket experiences large and cyclic changes in temperature as a result of solar heating. Tank wall heating can induce thermal stratification and propellant boiloff, particularly during slosh-inducing vehicle maneuvers. Precise understanding of the dynamic and thermodynamic effects of propellant slosh caused by these maneuvers is critical to mission performance and success. Computational fluid dynamics (CFD) analysis is used extensively within the space vehicle industry in an attempt to characterize the behavior of liquids in microgravity, yet experimental data to quantify these predictions is very limited and reduces confidence in the analytical predictions. A novel approach designed to produce high-fidelity data for correlation to CFD model predictions is being developed with the assistance of Florida Institute of Technology (FIT) and Sierra Lobo, Inc. With few exceptions, previous work in slosh dynamics was theoretical or treated the mass of fuel as a variable of inertia only; such models did not consider the viscosity, surface tension, or other important fluid effects. The challenges in this research are in the development of instrumentation able to measure the required parameters, the computational ability to quantify the fluid behaviors, and the means to assess both the measurements and predictions. The design of this experiment bridges the understanding of slosh dynamics in microgravity by a comprehensive approach that combines CFD tools, dynamic simulation tools, semianalytical models of the predominant fluid effects, and an experimental framework that includes measurement and characterization of liquid slosh in one-degree-of-freedom (DOF) and two-DOF experiments, and ultimately experiments in a NASA low-gravity aircraft.
PLUME-MoM 1.0: a new 1-D model of volcanic plumes based on the method of moments
NASA Astrophysics Data System (ADS)
de'Michieli Vitturi, M.; Neri, A.; Barsotti, S.
2015-05-01
In this paper a new mathematical model for volcanic plumes, named PlumeMoM, is presented. The model describes the steady-state 1-D dynamics of the plume in a 3-D coordinate system, accounting for continuous variability in particle distribution of the pyroclastic mixture ejected at the vent. Volcanic plumes are composed of pyroclastic particles of many different sizes ranging from a few microns up to several centimeters and more. Proper description of such a multiparticle nature is crucial when quantifying changes in grain-size distribution along the plume and, therefore, for better characterization of source conditions of ash dispersal models. The new model is based on the method of moments, which allows description of the pyroclastic mixture dynamics not only in the spatial domain but also in the space of properties of the continuous size-distribution of the particles. This is achieved by formulation of fundamental transport equations for the multiparticle mixture with respect to the different moments of the grain-size distribution. Different formulations, in terms of the distribution of the particle number, as well as of the mass distribution expressed in terms of the Krumbein log scale, are also derived. Comparison between the new moments-based formulation and the classical approach, based on the discretization of the mixture in N discrete phases, shows that the new model allows the same results to be obtained with a significantly lower computational cost (particularly when a large number of discrete phases is adopted). Application of the new model, coupled with uncertainty quantification and global sensitivity analyses, enables investigation of the response of four key output variables (mean and standard deviation (SD) of the grain-size distribution at the top of the plume, plume height and amount of mass lost by the plume during the ascent) to changes in the main input parameters (mean and SD) characterizing the pyroclastic mixture at the base of the plume
NASA Astrophysics Data System (ADS)
Driba, D. L.; De Lucia, M.; Peiffer, S.
2014-12-01
Fluid-rock interactions in geothermal reservoirs are driven by the state of disequilibrium that persists among solid and solutes due to changing temperature and pressure. During operation of enhanced geothermal systems, injection of cooled water back into the reservoir disturbs the initial thermodynamic equilibrium between the reservoir and its geothermal fluid, which may induce modifications in permeability through changes in porosity and pore space geometry, consequently bringing about several impairments to the overall system.Modeling of fluid-rock interactions induced by injection of cold brine into Groß Schönebeck geothermal reservoir system situated in the Rotliegend sandstone at 4200m depth have been done by coupling geochemical modeling Code Phreeqc with OpenGeoSys. Through batch modeling the re-evaluation of the measured hydrochemical composition of the brine has been done using Quintessa databases, the results from the calculation indicate that a mineral phases comprising of K-feldspar, hematite, Barite, Calcite and Dolomite was found to match the hypothesis of equilibrium with the formation fluid, Reducing conditions are presumed in the model (pe = -3.5) in order to match the amount of observed dissolved Fe and thus considered as initial state for the reactive transport modeling. based on a measured composition of formation fluids and the predominant mineralogical assemblage of the host rock, a preliminary 1D Reactive transport modeling (RTM) was run with total time set to 30 years; results obtained for the initial simulation revealed that during this period, no significant change is evident for K-feldspar. Furthermore, the precipitation of calcite along the flow path in the brine results in a drop of pH from 6.2 to a value of 5.2 noticed over the simulated period. The circulation of cooled fluid in the reservoir is predicted to affect the temperature of the reservoir within the first 100 -150m from the injection well. Examination of porosity change in
Bamberger, J.A.; Eyler, L.L.; Dodge, R.E.
1993-04-01
The objective of this work is to analyze the Hanford Waste Vitrification Project (HWVP) feed preparation tank mixing pump agitation design. This was accomplished by (1) reviewing mixing pump characteristics, (2) performing computer modeling of jet mixing and particulate material transport, (3) evaluating the propensity of the tank and mixing pump design to maintain particulate material in the tank in a uniformly mixed state, and (4) identifying important design parameters required to ensure optimum homogeneity and solids content during batch transfers.
Fort, J.A.; Bamberger, J.A.; Bates, J.M.; Enderlin, C.W.; Elmore, M.R.
1993-01-01
Hanford tank 241-SY-101 is a 75-ft-dia double-shell tank that contains approximately 1.1 M gal of radioactive fuel reprocessing waste. Core samples have shown that the tank contents are separated into two main layers, a article laden supernatant liquid at the top of the tank and a more dense slurry on the bottom. Two additional layers may be present, one being a potentially thick sludge lying beneath the slurry at the bottom of the tank and the other being the crust that has formed on the surface of the supernatant liquid. The supernatant is more commonly referred to as the convective layer and the slurry as the non-convective layer. Accumulation of gas (partly hydrogen) in the non-convective layer is suspected to be the key mechanism behind the gas burp phenomena, and several mitigation schemes are being developed to encourage a more uniform gas release rate (Benegas 1992). To support the full-scale hydraulic mitigation test, scaled experiments were performed to satisfy two objectives: 1. provide an experimental database for numerical- model validation; 2. establish operating parameter values required to mobilize the settled solids and maintain the solids in suspension.
NASA Astrophysics Data System (ADS)
Shia, R.
2012-12-01
The haze layer in Titan's upper atmosphere absorbs 90% of the solar radiation, but is inefficient for trapping infrared radiation generated by the surface. Its existence partially compensates for the greenhouse warming and keeps the surface approximately 9°C cooler than would otherwise be expected from the greenhouse effect alone. This is the so called anti-greenhouse effect (McKay et al., 1991). This effect can be used to alleviate the warming caused by the increasing level of greenhouse gases in the Earth's atmosphere. A one-dimensional radiative convective model (Kasting et al., 2009 and references listed there) is used to investigate the anti-greenhouse effect in the Earth atmosphere. Increasing of solar absorbers, e.g. aerosols and ozone, in the stratosphere reduces the surface solar flux and cool the surface. However, the absorption of the solar flux also increases the temperature in the upper atmosphere, while reduces the temperature at the surface. Thus, the temperature profile of the atmosphere changes and the regions with positive vertical temperature gradient are expanded. According to Shia (2010) the radiative forcing of greenhouse gases is directly related to the vertical temperature gradient. Under the new temperature profile increases of greenhouse gases should have less warming effect. When the solar absorbers keep increasing, eventually most of the atmosphere has positive temperature gradient and increasing greenhouse gases would cool the surface (Shia, 2011). The doubling CO2 scenario in the Earth atmosphere is simulated for different levels of solar absorbers using the 1-D RC model. The model results show that if the solar absorber increases to a certain level that less than 50% solar flux reaching the surface, doubling CO2 cools the surface by about 2 C. This means if the snowball Earth is generated by solar absorbers in the stratosphere, increasing greenhouse gases would make it freeze even more (Shia, 2011). References: Kasting, J. et al
NASA Astrophysics Data System (ADS)
Nekrasov, V. O.
2016-10-01
The article carries out a statistical data processing of quantitative and territorial division of oil tanks operating in Tyumen region, intended for reception, storage and distribution of commercial oil through trunk pipelines. It describes the working principle of the new device of erosion and prevention of oil bottom sediment formation with tangential supply of oil pumped into reservoir. The most significant similarity criteria can be emphasized in modeling rotational flows exerting significant influence on the structure of the circulating flow of oil in tank when operation of the device described. The dependence of the distribution of the linear velocity of a point on the surface along the radius at the circular motion of the oil in the tank is characterized, and on the basis of this dependence, a formula of general kinetic energy of rotational motion of oil and asphalt-resin-paraffin deposits total volume in the oil reservoir is given.
NASA Astrophysics Data System (ADS)
Habert, J.; Ricci, S.; Le Pape, E.; Thual, O.; Piacentini, A.; Goutal, N.; Jonville, G.; Rochoux, M.
2016-01-01
This paper presents a data-driven hydrodynamic simulator based on the 1-D hydraulic solver dedicated to flood forecasting with lead time of an hour up to 24 h. The goal of the study is to reduce uncertainties in the hydraulic model and thus provide more reliable simulations and forecasts in real time for operational use by the national hydrometeorological flood forecasting center in France. Previous studies have shown that sequential assimilation of water level or discharge data allows to adjust the inflows to the hydraulic network resulting in a significant improvement of the discharge while leaving the water level state imperfect. Two strategies are proposed here to improve the water level-discharge relation in the model. At first, a modeling strategy consists in improving the description of the river bed geometry using topographic and bathymetric measurements. Secondly, an inverse modeling strategy proposes to locally correct friction coefficients in the river bed and the flood plain through the assimilation of in situ water level measurements. This approach is based on an Extended Kalman filter algorithm that sequentially assimilates data to infer the upstream and lateral inflows at first and then the friction coefficients. It provides a time varying correction of the hydrological boundary conditions and hydraulic parameters. The merits of both strategies are demonstrated on the Marne catchment in France for eight validation flood events and the January 2004 flood event is used as an illustrative example throughout the paper. The Nash-Sutcliffe criterion for water level is improved from 0.135 to 0.832 for a 12-h forecast lead time with the data assimilation strategy. These developments have been implemented at the SAMA SPC (local flood forecasting service in the Haute-Marne French department) and used for operational forecast since 2013. They were shown to provide an efficient tool for evaluating flood risk and to improve the flood early warning system
Torfs, Elena; Martí, M Carmen; Locatelli, Florent; Balemans, Sophie; Bürger, Raimund; Diehl, Stefan; Laurent, Julien; Vanrolleghem, Peter A; François, Pierre; Nopens, Ingmar
2017-02-01
A new perspective on the modelling of settling behaviour in water resource recovery facilities is introduced. The ultimate goal is to describe in a unified way the processes taking place both in primary settling tanks (PSTs) and secondary settling tanks (SSTs) for a more detailed operation and control. First, experimental evidence is provided, pointing out distributed particle properties (such as size, shape, density, porosity, and flocculation state) as an important common source of distributed settling behaviour in different settling unit processes and throughout different settling regimes (discrete, hindered and compression settling). Subsequently, a unified model framework that considers several particle classes is proposed in order to describe distributions in settling behaviour as well as the effect of variations in particle properties on the settling process. The result is a set of partial differential equations (PDEs) that are valid from dilute concentrations, where they correspond to discrete settling, to concentrated suspensions, where they correspond to compression settling. Consequently, these PDEs model both PSTs and SSTs.
NASA Astrophysics Data System (ADS)
Melwani Daswani, Mohit; Schwenzer, Susanne P.; Reed, Mark H.; Wright, Ian P.; Grady, Monica M.
2016-11-01
Clay minerals, although ubiquitous on the ancient terrains of Mars, have not been observed in Martian meteorite Allan Hills (ALH) 84001, which is an orthopyroxenite sample of the early Martian crust with a secondary carbonate assemblage. We used a low-temperature (20 °C) one-dimensional (1-D) transport thermochemical model to investigate the possible aqueous alteration processes that produced the carbonate assemblage of ALH 84001 while avoiding the coprecipitation of clay minerals. We found that the carbonate in ALH 84001 could have been produced in a process, whereby a low-temperature ( 20 °C) fluid, initially equilibrated with the early Martian atmosphere, moved through surficial clay mineral and silica-rich layers, percolated through the parent rock of the meteorite, and precipitated carbonates (thereby decreasing the partial pressure of CO2) as it evaporated. This finding requires that before encountering the unweathered orthopyroxenite host of ALH 84001, the fluid permeated rock that became weathered during the process. We were able to predict the composition of the clay minerals formed during weathering, which included the dioctahedral smectite nontronite, kaolinite, and chlorite, all of which have been previously detected on Mars. We also calculated host rock replacement in local equilibrium conditions by the hydrated silicate talc, which is typically considered to be a higher temperature hydrothermal phase on Earth, but may have been a common constituent in the formation of Martian soils through pervasive aqueous alteration. Finally, goethite and magnetite were also found to precipitate in the secondary alteration assemblage, the latter associated with the generation of H2. Apparently, despite the limited water-rock interaction that must have led to the formation of the carbonates 3.9 Ga ago, in the vicinity of the ALH 84001 source rocks, clay formation would have been widespread.
NASA Astrophysics Data System (ADS)
Mogensen, Ditte; Aaltonen, Hermanni; Aalto, Juho; Bäck, Jaana; Kieloaho, Antti-Jussi; Gierens, Rosa; Smolander, Sampo; Kulmala, Markku; Boy, Michael
2015-04-01
Volatile organic compounds (VOCs) are emitted from the biosphere and can work as precursor gases for aerosol particles that can affect the climate (e.g. Makkonen et al., ACP, 2012). VOC emissions from needles and leaves have gained the most attention, however other parts of the ecosystem also have the ability to emit a vast amount of VOCs. This, often neglected, source can be important e.g. at periods where leaves are absent. Both sources and drivers related to forest floor emission of VOCs are currently limited. It is thought that the sources are mainly due to degradation of organic matter (Isidorov and Jdanova, Chemosphere, 2002), living roots (Asensio et al., Soil Biol. Biochem., 2008) and ground vegetation. The drivers are biotic (e.g. microbes) and abiotic (e.g. temperature and moisture). However, the relative importance of the sources and the drivers individually are currently poorly understood. Further, the relative importance of these factors is highly dependent on the tree species occupying the area of interest. The emission of isoprene and monoterpenes where measured from the boreal forest floor at the SMEAR II station in Southern Finland (Hari and Kulmala, Boreal Env. Res., 2005) during the snow-free period in 2010-2012. We used a dynamic method with 3 automated chambers analyzed by Proton Transfer Reaction - Mass Spectrometer (Aaltonen et al., Plant Soil, 2013). Using this data, we have developed empirical parameterizations for the emission of isoprene and monoterpenes from the forest floor. These parameterizations depends on abiotic factors, however, since the parameterizations are based on field measurements, biotic features are captured. Further, we have used the 1D chemistry-transport model SOSAA (Boy et al., ACP, 2011) to test the seasonal relative importance of inclusion of these parameterizations of the forest floor compared to the canopy crown emissions, on the atmospheric reactivity throughout the canopy.
Helical Floquet Channels in 1D Lattices
NASA Astrophysics Data System (ADS)
Budich, Jan Carl; Hu, Ying; Zoller, Peter
2017-03-01
We show how dispersionless channels exhibiting perfect spin-momentum locking can arise in a 1D lattice model. While such spectra are forbidden by fermion doubling in static 1D systems, here we demonstrate their appearance in the stroboscopic dynamics of a periodically driven system. Remarkably, this phenomenon does not rely on any adiabatic assumptions, in contrast to the well known Thouless pump and related models of adiabatic spin pumps. The proposed setup is shown to be experimentally feasible with state-of-the-art techniques used to control ultracold alkaline earth atoms in optical lattices.
NASA Astrophysics Data System (ADS)
Daehne, A.; van Asch, Th. W. J.; Corsini, A.; Spickerman, A.; Bégueria-Portuguès, S.
2010-05-01
Understanding the behavior of landslides often starts with a numerical simulation that accurately accounts for observed physical processes. This research proposes a method for the implementation of the dynamic SLOWMOVE model to a high-mobility, moderate velocity earth flow located in the northern Apennines. The Valoria landslide is 3.5 km long earth slide- earth flow that resumed activity in 2001. Landslide materials comprised of disaggregated Flysch, Marl and Claystones are mainly transported as earth slides in the upper slope, and as earth flows in the main track. Repeated acceleration events lasting several weeks occur seasonally since 2001 reactivation. During events it can reach velocities of about 10 m per hour with a cumulative displacement of hundreds of meters. Through this intermittent activity, more than ten million cubic meters have been transferred down-slope since 2001, changing significantly and several times the morphology of the slope. The SLOWMOVE model postulates that landslide materials can be represented as a homogeneous material with rheological properties and constant density. The approach is based on the Navier-Stokes equations. Under the assumptions that the inertia of the moving mass can be neglected, the behavior of the landslide depends solely on the balance between driving forces and resisting forces which contain a Coulomb-viscous component. Excess pore pressure due to undrained loading and lateral force form the main parameters that control the acceleration. The effects of lateral force and excess pore pressure allow a numerical simulation of landslide reactivation by coupling of two landslide bodies. A numerical scheme based on a finite difference solution (2D Eulerian space with Cartesian coordinates) was implemented in Microsoft Excel and used to compute propagation of the mass in 1D. The model allows coupling between mass movements having different geotechnical characteristic. In practice, it allows simulating the reactivation of
Testing of Densified Liquid Hydrogen Stratification in a Scale Model Propellant Tank
NASA Technical Reports Server (NTRS)
Jurns, John M.; Tomsik, Thomas M.; Greene, William D.
2001-01-01
This paper describes a test program that was conducted at NASA to demonstrate the ability to load densified LH2 into a subscale propellant tank. This work was done through a collaborative effort between NASA Glenn Research Center and the Lockheed Martin Michoud Space Systems (LMMSS). The Multilobe tank, which was made from composite materials similar to that to be used on X-33, was formed from two lobes with a center septum. Test results are shown for data that was collected on filling the subscale tank with densified liquid hydrogen (DLH2) propellant that was produced at the NASA Plum Brook Station. Data is compared to analytical predictions. Data collected for this test series agrees well with analytical predictions of the environmental heat leak into the tank and the thermal stratification characteristics of the hydrogen propellant in the tank as it was filled with DLH2.
NASA Astrophysics Data System (ADS)
Murray, Keenan A.; Kramer, Louisa J.; Doskey, Paul V.; Ganzeveld, Laurens; Seok, Brian; Van Dam, Brie; Helmig, Detlev
2015-09-01
Observed depth profiles of nitric oxide (NO), nitrogen dioxide (NO2), and ozone (O3) in snowpack interstitial air at Summit, Greenland were best replicated by a 1-D process-scale model, which included (1) geometrical representation of snow grains as spheres, (2) aqueous-phase chemistry confined to a quasi-liquid layer (QLL) on the surface of snow grains, and (3) initialization of the species concentrations in the QLL through equilibrium partitioning with mixing ratios in snowpack interstitial air. A comprehensive suite of measurements in and above snowpack during a high O3 event facilitated analysis of the relationship between the chemistry of snowpack and the overlying atmosphere. The model successfully reproduced 2 maxima (i.e., a peak near the surface of the snowpack at solar noon and a larger peak occurring in the evening that extended down from 0.5 to 2 m) in the diurnal profile of NO2 within snowpack interstitial air. The maximum production rate of NO2 by photolysis of nitrate (NO3-) was approximately 108 molec cm-3 s-1, which explained daily observations of maxima in NO2 mixing ratios near solar noon. Mixing ratios of NO2 in snowpack interstitial air were greatest in the deepest layers of the snowpack at night and were attributed to thermal decomposition of peroxynitric acid, which produced up to 106 molec NO2 cm-3 s-1. Highest levels of NO in snowpack interstitial air were confined to upper layers of the snowpack and observed profiles were consistent with photolysis of NO2. Production of nitrogen oxides (NOx) from NO3- photolysis was estimated to be two orders of magnitude larger than NO production and supports the hypothesis that NO3- photolysis is the primary source of NOx within sunlit snowpack in the Arctic. Aqueous-phase oxidation of formic acid by O3 resulted in a maximum consumption rate of ∼106-107 molec cm-3 s-1 and was the primary removal mechanism for O3.
Pedrós, Ignacio; Petrov, Dmitry; Allgaier, Michael; Sureda, Francesc; Barroso, Emma; Beas-Zarate, Carlos; Auladell, Carme; Pallàs, Mercè; Vázquez-Carrera, Manuel; Casadesús, Gemma; Folch, Jaume; Camins, Antoni
2014-09-01
The present study had focused on the behavioral phenotype and gene expression profile of molecules related to insulin receptor signaling in the hippocampus of 3 and 6 month-old APPswe/PS1dE9 (APP/PS1) transgenic mouse model of Alzheimer's disease (AD). Elevated levels of the insoluble Aβ (1-42) were detected in the brain extracts of the transgenic animals as early as 3 months of age, prior to the Aβ plaque formation (pre-plaque stage). By the early plaque stage (6 months) both the soluble and insoluble Aβ (1-40) and Aβ (1-42) peptides were detectable. We studied the expression of genes related to memory function (Arc, Fos), insulin signaling, including insulin receptor (Insr), Irs1 and Irs2, as well as genes involved in insulin growth factor pathways, such as Igf1, Igf2, Igfr and Igfbp2. We also examined the expression and protein levels of key molecules related to energy metabolism (PGC1-α, and AMPK) and mitochondrial functionality (OXPHOS, TFAM, NRF1 and NRF2). 6 month-old APP/PS1 mice demonstrated impaired cognitive ability, were glucose intolerant and showed a significant reduction in hippocampal Insr and Irs2 transcripts. Further observations also suggest alterations in key cellular energy sensors that regulate the activities of a number of metabolic enzymes through phosphorylation, such as a decrease in the Prkaa2 mRNA levels and in the pAMPK (Thr172)/Total APMK ratio. Moreover, mRNA and protein analysis reveals a significant downregulation of genes essential for mitochondrial replication and respiratory function, including PGC-1α in hippocampal extracts of APP/PS1 mice, compared to age-matched wild-type controls at 3 and 6 months of age. Overall, the findings of this study show early alterations in genes involved in insulin and energy metabolism pathways in an APP/PS1 model of AD. These changes affect the activity of key molecules like NRF1 and PGC-1α, which are involved in mitochondrial biogenesis. Our results reinforce the hypothesis that the
Leishear, R.; Poirier, M.; Fowley, M.
2011-05-26
The Salt Disposition Integration (SDI) portfolio of projects provides the infrastructure within existing Liquid Waste facilities to support the startup and long term operation of the Salt Waste Processing Facility (SWPF). Within SDI, the Blend and Feed Project will equip existing waste tanks in the Tank Farms to serve as Blend Tanks where 300,000-800,000 gallons of salt solution will be blended in 1.3 million gallon tanks and qualified for use as feedstock for SWPF. Blending requires the miscible salt solutions from potentially multiple source tanks per batch to be well mixed without disturbing settled sludge solids that may be present in a Blend Tank. Disturbing solids may be problematic both from a feed quality perspective as well as from a process safety perspective where hydrogen release from the sludge is a potential flammability concern. To develop the necessary technical basis for the design and operation of blending equipment, Savannah River National Laboratory (SRNL) completed scaled blending and transfer pump tests and computational fluid dynamics (CFD) modeling. A 94 inch diameter pilot-scale blending tank, including tank internals such as the blending pump, transfer pump, removable cooling coils, and center column, were used in this research. The test tank represents a 1/10.85 scaled version of an 85 foot diameter, Type IIIA, nuclear waste tank that may be typical of Blend Tanks used in SDI. Specifically, Tank 50 was selected as the tank to be modeled per the SRR, Project Engineering Manager. SRNL blending tests investigated various fixed position, non-rotating, dual nozzle pump designs, including a blending pump model provided by the blend pump vendor, Curtiss Wright (CW). Primary research goals were to assess blending times and to evaluate incipient sludge disturbance for waste tanks. Incipient sludge disturbance was defined by SRR and SRNL as minor blending of settled sludge from the tank bottom into suspension due to blending pump operation, where
Leishear, R.; Poirier, M.; Lee, S.; Fowley, M.
2012-06-26
This paper documents testing methods, statistical data analysis, and a comparison of experimental results to CFD models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an eight foot diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors such as turbulence, pump fluctuations, and eddies required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations -- or scatter -- occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times were shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy, and determined statistical correction factors that can be applied to CFD models, and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design, and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending, using a pump with dual opposing jets which re-circulate fluids in the tank to promote blending when fluids are added to the tank. In all, eighty-five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full scale, liquid radioactive waste storage tank. Also, different jet
2016-07-01
are considering passive management approaches like flushing and routing to manage reservoir sediment. In the last 3 years, HEC developed new analysis...Kansas River) (Gibson and Boyd 2014; Davis et al. 2014; Shelley and Gibson 2015). However, because these reservoir management strategies are still...alternative sediment management objectives, these models are uncelebrated and therefore, somewhat speculative. One of the problems with modeling
Tank characterization reference guide
De Lorenzo, D.S.; DiCenso, A.T.; Hiller, D.B.; Johnson, K.W.; Rutherford, J.H.; Smith, D.J.; Simpson, B.C.
1994-09-01
Characterization of the Hanford Site high-level waste storage tanks supports safety issue resolution; operations and maintenance requirements; and retrieval, pretreatment, vitrification, and disposal technology development. Technical, historical, and programmatic information about the waste tanks is often scattered among many sources, if it is documented at all. This Tank Characterization Reference Guide, therefore, serves as a common location for much of the generic tank information that is otherwise contained in many documents. The report is intended to be an introduction to the issues and history surrounding the generation, storage, and management of the liquid process wastes, and a presentation of the sampling, analysis, and modeling activities that support the current waste characterization. This report should provide a basis upon which those unfamiliar with the Hanford Site tank farms can start their research.
Modeling DBPs formation in drinking water in residential plumbing pipes and hot water tanks.
Chowdhury, Shakhawat; Rodriguez, Manuel J; Sadiq, Rehan; Serodes, Jean
2011-01-01
Disinfection byproducts (DBPs) in municipal supply water are a concern because of their possible risks to human health. Risk assessment studies often use DBP data in water distribution systems (WDS). However, DBPs in tap water may be different because of stagnation of the water in plumbing pipes (PP) and heating in hot water tanks (HWT). This study investigated occurrences and developed predictive models for DBPs in the PP and the HWT of six houses from three municipal water systems in Quebec (Canada) in a year-round study. Trihalomethanes (THMs) in PP and HWT were observed to be 1.4-1.8 and 1.9-2.7 times the THMs in the WDS, respectively. Haloacetic acid (HAAs) in PP and HWT were observed to be variable (PP/WDS = 0.23-2.24; HWT/WDS = 0.53-2.61). Using DBPs occurrence data from these systems, three types of linear models (main factors; main factors, interactions and higher orders; logarithmic) and two types of nonlinear models (three parameters Logistic and four parameters Weibull) were investigated to predict DBPs in the PP and HWT. Significant factors affecting DBPs formation in the PP and HWT were identified through numerical and graphical techniques. The R(2) values of the models varied between 0.77 and 0.96, indicating excellent predictive ability for THMs and HAAs in the PP and the HWT. The models were found to be statistically significant. The models were validated using additional data. These models can be used to predict DBPs increase from WDS (water entry point of house) to the PP and HWT, and could thereby help gain a better understanding of human exposure to DBPs and their associated risks.
NASA Astrophysics Data System (ADS)
Lei, Wang; Yanzhong, Li; Zhan, Liu; Kang, Zhu
An improved CFD model involving a multi-component gas mixturein the ullage is constructed to predict the pressurization behavior of a cryogenic tank considering the existence of pressurizing helium.A temperature difference between the local fluid and its saturation temperature corresponding to the vapor partial pressure is taken as the phase change driving force. As practical application of the model, hydrogen and oxygen tanks with helium pressurization arenumerically simulated by using themulti-component gas model. The results presentthat the improved model produce higher ullage temperature and pressure and lower wall temperaturethan those without multi-component consideration. The phase change has a slight influence on thepressurization performance due to the small quantities involved.
Murcia, M D; Gómez, M; Bastida, J; Hidalgo, A M; Montiel, M C; Ortega, S
2014-08-01
A continuous tank reactor was used to remove 4-chlorophenol from aqueous solutions, using immobilized soybean peroxidase and hydrogen peroxide. The influence of operational variables (enzyme and substrate concentrations and spatial time) on the removal efficiency was studied. By using the kinetic law and the intrinsic kinetic parameters obtained in a previous work with a discontinuous tank reactor, the mass-balance differential equations of the transient state reactor model were solved and the theoretical conversion values were calculated. Several experimental series were used to obtain the values of the remaining model parameters by numerical calculation and using an error minimization algorithm. The model was checked by comparing the results obtained in some experiments (not used for the determination of the parameters) and the theoretical ones. The good concordance between the experimental and calculated conversion values confirmed that the design model can be used to predict the transient behaviour of the reactor.
NASA Astrophysics Data System (ADS)
Maher Abourabia, Aly; Hassan, Kawsar Mohammad; Abo-Elghar, Eman Mohammad
2015-02-01
We investigate a bio-system composed of a shape memory alloy (SMA) immersed and subjected to heat convection in a blood vessel, affected by heart beats that create a wave motion of long wavelength. The tackled model in (2+1)-D is based on the continuity and momentum equations for the fluid phase, besides; the state of the SMA are described via previous works in the form of statistical distributions of energy for both Martensite and Austenite phases. The solution based on the reductive perturbation technique gives a thermal diffusion-like equation as a key for expressing the temperature and velocity components of the blood. In terms of two cases concerning the difference between the wave numbers in the perpendicular directions, it is found that the system's temperature increases nonlinearly from a minimum initial temperature 293 K (20 °C) up to a maximum value about 316.68 K (43.68 °C), then tends to decrease along the blood flow (anisotropy of K and L) direction. In both cases it is observed that the SMA acquires most of this temperature raising not the blood because of its conventional biological limits (37-40 °C). The range of the heart beats wave numbers characteristic for each person plays an important role in realizing phase changes in the anisotropic case leading to the formation of the hysteresis loops Martensite-Austenite-Martensite or vice versa, according to the energy variation. The entropy generation σ is investigated for the system (Blood + SMA), it predicts that along the flow direction the system gains energy convectively up to a maximum value, then reverses his tendency to gradually loosing energy passing by the equilibrium state, then the system looses energy to the surroundings by the same amount which was gained beforehand. The loss diminishes but stops before arriving to equilibrium again. For certain differences in wave numbers the system starts to store energy again after it passes by the state of equilibrium for the second time. In the
NASA Astrophysics Data System (ADS)
Majumdar, Alok; Valenzuela, Juan; LeClair, Andre; Moder, Jeff
2016-03-01
This paper presents a numerical model of a system-level test bed-the multipurpose hydrogen test bed (MHTB) using the Generalized Fluid System Simulation Program (GFSSP). MHTB is representative in size and shape of a space transportation vehicle liquid hydrogen propellant tank, and ground-based testing was performed at NASA Marshall Space Flight Center (MSFC) to generate data for cryogenic storage. GFSSP is a finite volume-based network flow analysis software developed at MSFC and used for thermofluid analysis of propulsion systems. GFSSP has been used to model the self-pressurization and ullage pressure control by the Thermodynamic Vent System (TVS). A TVS typically includes a Joule-Thompson (J-T) expansion device, a two-phase heat exchanger (HEX), and a mixing pump and liquid injector to extract thermal energy from the tank without significant loss of liquid propellant. For the MHTB tank, the HEX and liquid injector are combined into a vertical spray bar assembly. Two GFSSP models (Self-Pressurization and TVS) were separately developed and tested and then integrated to simulate the entire system. The Self-Pressurization model consists of multiple ullage nodes, a propellant node, and solid nodes; it computes the heat transfer through multilayer insulation blankets and calculates heat and mass transfer between the ullage and liquid propellant and the ullage and tank wall. A TVS model calculates the flow through a J-T valve, HEX, and spray and vent systems. Two models are integrated by exchanging data through User Subroutines of both models. Results of the integrated models have been compared with MHTB test data at a 50% fill level. Satisfactory comparison was observed between tests and numerical predictions.
Thermal modeling of core sampling in flammable gas waste tanks. Part 2: Rotary-mode sampling
Unal, C.; Poston, D.; Pasamehmetoglu, K.O.; Witwer, K.S.
1997-08-01
The radioactive waste stored in underground storage tanks at Hanford site includes mixtures of sodium nitrate and sodium nitrite with organic compounds. The waste can produce undesired violent exothermic reactions when heated locally during the rotary-mode sampling. Experiments are performed varying the downward force at a maximum rotational speed of 55 rpm and minimum nitrogen purge flow of 30 scfm. The rotary drill bit teeth-face temperatures are measured. The waste is simulated with a low thermal conductivity hard material, pumice blocks. A torque meter is used to determine the energy provided to the drill string. The exhaust air-chip temperature as well as drill string and drill bit temperatures and other key operating parameters were recorded. A two-dimensional thermal model is developed. The safe operating conditions were determined for normal operating conditions. A downward force of 750 at 55 rpm and 30 scfm nitrogen purge flow was found to yield acceptable substrate temperatures. The model predicted experimental results reasonably well. Therefore, it could be used to simulate abnormal conditions to develop procedures for safe operations.
Tank Tests of NACA Model 40 Series of Hulls for Small Flying Boats and Amphibians
NASA Technical Reports Server (NTRS)
Parkinson, John B; Dawson, John R
1937-01-01
The NACA model 40 series of flying-boat hull models consists of 2 forebodies and 3 afterbodies combined to provide several forms suitable for use in small marine aircraft. One forebody is the usual form with hollow bow sections and the other has a bottom surface that is completely developable from bow to step. The afterbodies include a short pointed afterbody with an extension for the tail surfaces, a long afterbody similar to that of a seaplane float but long enough to carry the tail surfaces, and a third obtained by fitting a second step in the latter afterbody. The various combinations were tested in the NACA Tank by the general method over a suitable range of loadings. Fixed-trim tests were made for all speeds likely to be used and free-to-trim tests were made at low speeds to slightly beyond the hump speed. The characteristics of the hulls at best trim angles have been deduced from the data of the tests at fixed trim angles and are given in the form of nondimensional coefficients applicable to any size hull.
Zhang, HD; Deria, P; Farha, OK; Hupp, JT; Snurr, RQ
2015-01-01
Metal-organic frameworks (MOFs) are promising materials for storing natural gas in vehicular applications. Evaluation of these materials has focused on adsorption of pure methane, although commercial natural gas also contains small amounts of higher hydrocarbons such as ethane and propane, which adsorb more strongly than methane. There is, thus, a possibility that these higher hydrocarbons will accumulate in the MOF after multiple operating (adsorption/desorption) cycles, and reduce the storage capacity. To study the net effect of ethane and propane on the performance of an adsorbed natural gas (ANG) tank, we developed a mathematical model based on thermodynamics and mass balance equations that describes the state of the tank at any instant. The required inputs are the pure-component isotherms, and mixture adsorption data are calculated using the Ideal Adsorbed Solution Theory (IAST). We focused on how the "deliverable energy'' provided by the ANG tank to the engine changed over 200 operating cycles for a sample of 120 MOF structures. We found that, with any MOF, the ANG tank performance monotonically declines during early operating cycles until a "cyclic steady state'' is reached. We determined that the best materials when the fuel is 100% methane are not necessarily the best when the fuel includes ethane and propane. Among the materials tested, some top MOFs are MOF-143 > NU-800 > IRMOF-14 > IRMOF-20 > MIL-100 > NU-125 > IRMOF-1 > NU-111. MOF-143 is predicted to deliver 5.43 MJ L-1 of tank to the engine once the cyclic steady state is reached. The model also provided insights that can assist in future work to discover more promising adsorbent materials for natural gas storage.
NASA Technical Reports Server (NTRS)
2001-01-01
A new inspection robot from Solex Robotics Systems was designed to eliminate hazardous inspections of petroleum and chemical storage tanks. The submersible robot, named Maverick, is used to inspect the bottoms of tanks, keeping the tanks operational during inspection. Maverick is able to provide services that will make manual tank inspections obsolete. While the inspection is conducted, Maverick's remote human operators remain safe outside of the tank. The risk to human health and life is now virtually eliminated. The risk to the environment is also minimal because there is a reduced chance of spillage from emptying and cleaning the tanks, where previously, tons of pollutants were released through the process of draining and refilling.
NASA Astrophysics Data System (ADS)
Ilampooranan, I.; Muthiah, K.; Athikesavan, R.
2013-05-01
Hydrological Modeling of tank (small reservoirs) cascaded sub-basin of a semi-arid region is a complex process. Physically based approach can simulate the various processes in surface, unsaturated and saturated ground water zones of such sub basin in an integrated manner. The objectives of the study are (i) to characterize the study area to replicate the physical conditions of surface and saturated zones (ii) to carryout overland flow routing of a tank cascaded basin using physically based modular approach (iii) To simulate the ground water levels in the unconfined aquifer (iv) to study the surface and groundwater dynamics on incorporation of tank cascades in the integrated model. An integrated, physically based model MIKE 11 & MIKE SHE was applied to study the hydrological processes of a tank cascaded semi-arid basin in which flow through tanks were modeled using MIKE 11 and coupled with MIKE SHE in-order to best represent the surface water dynamics in a distributed manner. Sindapalli Uppodai sub-basin, Southern Tamilnadu, India is chosen as study area. There are 15 tanks connected in series forming a tank cascade. Other tanks and depressions in the sub basin are also considered for the study and their effectiveness were analysed. DEM was obtained from SRTM data. The maps such as drainage network, land use and soil are prepared. Soil sampling was carried out. The time series data of rainfall and climate parameters are given as input. The characterization of unconfined aquifer formation was done by Geo-Resistivity survey. 71 observation and pumping wells are monitored within and periphery of sub basin which are used for calibration of the model. The flow routing over the land is done by MIKE SHE's Overland Flow Module, using the diffusive wave approximation of the Saint Venant equation. The hydrograph of routed runoff from the tank cascaded catchment was obtained. The spatial and temporal variation of hydraulic head of the saturated ground water zone is simulated
NASA Technical Reports Server (NTRS)
Flachbart, Robin; Hedayat, Ali; Holt, Kimberly A.; Cruit, Wendy (Technical Monitor)
2001-01-01
The Advanced Shuttle Upper Stage (ASUS) concept addresses safety concerns associated .with cryogenic stages by launching empty, and filling on ascent. The ASUS employs a rapid chill and fill concept. A spray bar is used to completely chill the tank before fill, allowing the vent valve to be closed during the fill process. The first tests of this concept, using a flight size (not flight weight) tank. were conducted at Marshall Space Flight Center (MSFC) during the summer of 2000. The objectives of the testing were to: 1) demonstrate that a flight size tank could be filled in roughly 5 minutes to accommodate the shuttle ascent window, and 2) demonstrate a no-vent fill of the tank. A total of 12 tests were conducted. Models of the test facility fill and vent systems, as well as the tank, were constructed. The objective of achieving tank fill in 5 minutes was met during the test series. However, liquid began to accumulate in the tank before it was chilled. Since the tank was not chilled until the end of each test, vent valve closure during fill was not possible. Even though the chill and fill process did not occur as expected, reasonable model correlation with the test data was achieved.
NASA Astrophysics Data System (ADS)
Hedayat, A.; Cartagena, W.; Majumdar, A. K.; LeClair, A. C.
2016-03-01
NASA's future missions may require long-term storage and transfer of cryogenic propellants. The Engineering Development Unit (EDU), a NASA in-house effort supported by both Marshall Space Flight Center (MSFC) and Glenn Research Center, is a cryogenic fluid management (CFM) test article that primarily serves as a manufacturing pathfinder and a risk reduction task for a future CFM payload. The EDU test article comprises a flight-like tank, internal components, insulation, and attachment struts. The EDU is designed to perform integrated passive thermal control performance testing with liquid hydrogen (LH2) in a test-like vacuum environment. A series of tests, with LH2 as a testing fluid, was conducted at Test Stand 300 at MSFC during the summer of 2014. The objective of this effort was to develop a thermal/fluid model for evaluating the thermodynamic behavior of the EDU tank during the chill and fill processes. The Generalized Fluid System Simulation Program, an MSFC in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the chill and fill portion of the testing. The model contained the LH2 supply source, feed system, EDU tank, and vent system. The test setup, modeling description, and comparison of model predictions with the test data are presented.
NASA Astrophysics Data System (ADS)
Jones, Alan G.; Afonso, Juan Carlos; Fullea, Javier; Salajegheh, Farshad
2014-02-01
Modeling the continental lithosphere's physical properties, especially its depth extent, must be done within a self-consistent petrological-geophysical framework; modeling using only one or two data types may easily lead to inconsistencies and erroneous interpretations. Using the LitMod approach for hypothesis testing and first-order modeling, we show how assumptions made about crustal information and the probable compositions of the lithospheric and sub-lithospheric mantle affect particular observables, particularly especially surface topographic elevation. The critical crustal parameter is density, leading to ca. 600 m error in topography for 50 kg m- 3 imprecision. The next key parameter is crustal thickness, and uncertainties in its definition lead to around ca. 4 km uncertainty in LAB for every 1 km of variation in Moho depth. Possible errors in the other assumed crustal parameters introduce a few kilometers of uncertainty in the depth to the LAB. We use Ireland as a natural laboratory to demonstrate the approach. From first-order arguments and given reasonable assumptions, a topographic elevation in the range of 50-100 m, which is the average across Ireland, requires that the lithosphere-asthenosphere boundary (LAB) beneath most of Ireland must lie in the range 90-115 km. A somewhat shallower (to 85 km) LAB is permitted, but the crust must be thinned (< 29 km) to compensate. The observations, especially topography, are inconsistent with suggestions, based on interpretation of S-to-P receiver functions, that the LAB thins from 85 km in southern Ireland to 55 km in central northern Ireland over a distance of < 150 km. Such a thin lithosphere would result in over 1000 m of uplift, and such rapid thinning by 30 km over less than 150 km would yield significant north-south variations in topographic elevation, Bouguer anomaly, and geoid height, none of which are observed. Even juxtaposing the most extreme probable depleted composition for the lithospheric mantle
NASA Astrophysics Data System (ADS)
Rodriguez, D.; Miller, A.; Honeyman, B.
2007-12-01
The study of the transport of contaminants in groundwater is critical in order to mitigate risks to downstream receptors from sites where past releases of these contaminants has resulted in the degradation of the water quality of the underlying aquifer. In most cases, the fate and transport of these contaminants occurs in a chemically and physically heterogeneous environment; thereby making the prediction of the ultimate fate of these contaminants difficult. In order to better understand the fundamental processes that have the greatest effect on the transport of these contaminants, careful laboratory study must be completed in a controlled environment. Once the experimental data has been generated, the validation of numerical models may then be achieved. Questions on the management of contaminated sites may center on the long-term release (e.g., desorption, dissolution) behavior of contaminated geomedia. Data on the release of contaminants is often derived from bench-scale experiments or, in rare cases, through field-scale experiments. A central question, however, is how molecular-scale processes (e.g., bond breaking) are expressed at the macroscale. This presentation describes part of a collaborative study between the Colorado School of Mines, the USGS and Lawrence Berkeley National Lab on upscaling pore-scale processes to understanding field-scale observations. In the work described here, two experiments were conducted in two intermediate-scale tanks (2.44 m x 1.22 m x 7.6 cm and 2.44 m x 0.61 m x 7.6 cm) to generate data to quantify the processes of uranium dissolution and transport in fully saturated conditions, and to evaluate the ability of two reactive transport models to capture the relevant processes and predict U behavior at the intermediate scale. Each tank was designed so that spatial samples could be collected from the side of the tank, as well as samples from the effluent end of the tank. The larger tank was packed with a less than 2mm fraction of a
Savonenko, Alena; Xu, Guilian M; Melnikova, Tatiana; Morton, Johanna L; Gonzales, Victoria; Wong, Molly P F; Price, Donald L; Tang, Fai; Markowska, Alicja L; Borchelt, David R
2005-04-01
Transgenic mice made by crossing animals expressing mutant amyloid precursor protein (APPswe) to mutant presenilin 1 (PS1dE9) allow for incremental increases in Abeta42 production and provide a model of Alzheimer-type amyloidosis. Here, we examine cognition in 6- and 18-month old transgenic mice expressing APPswe and PS1dE9, alone and in combination. Spatial reference memory was assessed in a standard Morris Water Maze task followed by assessment of episodic-like memory in Repeated Reversal and Radial Water maze tasks. We then used factor analysis to relate changes in performance in these tasks with cholinergic markers, somatostatin levels, and amyloid burden. At 6 months of age, APPswe/PS1dE9 double-transgenic mice showed visible plaque deposition; however, all genotypes, including double-transgenic mice, were indistinguishable from nontransgenic animals in all cognitive measures. In the 18-month-old cohorts, amyloid burdens were much higher in APPswe/PS1dE9 mice with statistically significant but mild decreases in cholinergic markers (cortex and hippocampus) and somatostatin levels (cortex). APPswe/PS1dE9 mice performed all cognitive tasks less well than mice from all other genotypes. Factor and correlation analyses defined the strongest correlation as between deficits in episodic-like memory tasks and total Abeta loads in the brain. Collectively, we find that, in the APPswe/PS1dE9 mouse model, some form of Abeta associated with amyloid deposition can disrupt cognitive circuits when the cholinergic and somatostatinergic systems remain relatively intact; and that episodic-like memory seems to be more sensitive to the toxic effects of Abeta.
Pierson, Kayla L.; Belsher, Jeremy D.; Seniow, Kendra R.
2012-10-19
The mission of the DOE River Protection Project (RPP) is to store, retrieve, treat and dispose of Hanford's tank waste. Waste is retrieved from the underground tanks and delivered to the Waste Treatment and Immobilization Plant (WTP). Waste is processed through a pretreatment facility where it is separated into low activity waste (LAW), which is primarily liquid, and high level waste (HLW), which is primarily solid. The LAW and HLW are sent to two different vitrification facilities and glass canisters are then disposed of onsite (for LAW) or shipped off-site (for HLW). The RPP mission is modeled by the Hanford Tank Waste Operations Simulator (HTWOS), a dynamic flowsheet simulator and mass balance model that is used for mission analysis and strategic planning. The integrated solubility model (ISM) was developed to improve the chemistry basis in HTWOS and better predict the outcome of the RPP mission. The ISM uses a graded approach to focus on the components that have the greatest impact to the mission while building the infrastructure for continued future improvement and expansion. Components in the ISM are grouped depending upon their relative solubility and impact to the RPP mission. The solubility of each group of components is characterized by sub-models of varying levels of complexity, ranging from simplified correlations to a set of Pitzer equations used for the minimization of Gibbs Energy.
Hanford tank residual waste – contaminant source terms and release models
Deutsch, William J.; Cantrell, Kirk J.; Krupka, Kenneth M.; Lindberg, Michael J.; Serne, R. Jeffrey
2011-08-23
Residual waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the residual wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, residual waste from five tanks has been evaluated. Residual wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while residual wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U-Na-C-O-P±H phases are common in the U-rich residual wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all residual waste samples studied to date. Contaminant release from the residual wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)2-saturated solution, or a CaCO3-saturated water. Uranium release concentrations are highly dependent on waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U residual wastes, and also higher when leached with the CaCO3-saturated solution than with the Ca(OH)2-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the waste, and it appears to be slightly more leachable by the Ca(OH)2-saturated solution than by the CaCO3-saturated solution. In general, Tc is much less
Dodson, W.R.; Dimitrakopoulos, P.
2010-01-01
We develop a computationally efficient cytoskeleton-based continuum erythrocyte algorithm. The cytoskeleton is modeled as a two-dimensional elastic solid with comparable shearing and area-dilatation resistance that follows a material law (Skalak, R., A. Tozeren, R. P. Zarda, and S. Chien. 1973. Strain energy function of red blood cell membranes. Biophys. J. 13:245–264). Our modeling enforces the global area-incompressibility of the spectrin skeleton (being enclosed beneath the lipid bilayer in the erythrocyte membrane) via a nonstiff, and thus efficient, adaptive prestress procedure which accounts for the (locally) isotropic stress imposed by the lipid bilayer on the cytoskeleton. In addition, we investigate the dynamics of healthy human erythrocytes in strong shear flows with capillary number Ca = O(1) and small-to-moderate viscosity ratios 0.001 ≤ λ ≤ 1.5. These conditions correspond to a wide range of surrounding medium viscosities (4–600 mPa s) and shear flow rates (0.02–440 s−1), and match those used in ektacytometry systems. Our computational results on the cell deformability and tank-treading frequency are compared with ektacytometry findings. The tank-treading period is shown to be inversely proportional to the shear rate and to increase linearly with the ratio of the cytoplasm viscosity to that of the suspending medium. Our modeling also predicts that the cytoskeleton undergoes measurable local area dilatation and compression during the tank-treading of the cells. PMID:21044588
TankSIM: A Cryogenic Tank Performance Prediction Program
NASA Technical Reports Server (NTRS)
Bolshinskiy, L. G.; Hedayat, A.; Hastings, L. J.; Moder, J. P.; Schnell, A. R.; Sutherlin, S. G.
2015-01-01
Accurate prediction of the thermodynamic state of the cryogenic propellants in launch vehicle tanks is necessary for mission planning and successful execution. Cryogenic propellant storage and transfer in space environments requires that tank pressure be controlled. The pressure rise rate is determined by the complex interaction of external heat leak, fluid temperature stratification, and interfacial heat and mass transfer. If the required storage duration of a space mission is longer than the period in which the tank pressure reaches its allowable maximum, an appropriate pressure control method must be applied. Therefore, predictions of the pressurization rate and performance of pressure control techniques in cryogenic tanks are required for development of cryogenic fluid long-duration storage technology and planning of future space exploration missions. This paper describes an analytical tool, Tank System Integrated Model (TankSIM), which can be used for modeling pressure control and predicting the behavior of cryogenic propellant for long-term storage for future space missions. It is written in the FORTRAN 90 language and can be compiled with any Visual FORTRAN compiler. A thermodynamic vent system (TVS) is used to achieve tank pressure control. Utilizing TankSIM, the following processes can be modeled: tank self-pressurization, boiloff, ullage venting, and mixing. Details of the TankSIM program and comparisons of its predictions with test data for liquid hydrogen and liquid methane will be presented in the final paper.
Storage tanks under earthquake loading
Rammerstorfer, F.G.; Scharf, K. ); Fisher, F.D. )
1990-11-01
This is a state-of-the-art review of various treatments of earthquake loaded liquid filled shells by the methods of earthquake engineering, fluid dynamics, structural and soil dynamics, as well as the theory of stability and computational mechanics. Different types of tanks and different possibilities of tank failure will be discussed. The authors will emphasize cylindrical above-ground liquid storage tanks with vertical axis. But many of the treatments are also valid for other tank configurations. For the calculation of the dynamically activated pressure due to an earthquake a fluid-structure-soil interaction problem must be solved. The review will describe the methods, proposed by different authors, to solve this interaction problem. To study the dynamic behavior of liquid storage tanks, one must distinguish between anchored and unanchored tanks. In the case of an anchored tank, the tank bottom edge is fixed to the foundation. If the tank is unanchored, partial lifting of the tank's bottom may occur, and a strongly nonlinear problem has to be solved. They will compare the various analytical and numerical models applicable to this problem, in combination with experimental data. An essential aim of this review is to give a summary of methods applicable as tools for an earthquake resistant design, which can be used by an engineer engaged in the construction of liquid storage tanks.
Tuck, Geoffrey N.; Whitten, Athol R.
2013-01-01
Annual draft systems are the principal method used by teams in major sporting leagues to recruit amateur players. These draft systems frequently take one of three forms: a lottery style draft, a weighted draft, or a reverse-order draft. Reverse-order drafts can create incentives for teams to deliberately under-perform, or tank, due to the perceived gain from obtaining quality players at higher draft picks. This paper uses a dynamic simulation model that captures the key components of a win-maximising sporting league, including the amateur player draft, draft choice error, player productivity, and between-team competition, to explore how competitive balance and incentives to under-perform vary according to league characteristics. We find reverse-order drafts can lead to some teams cycling between success and failure and to other teams being stuck in mid-ranking positions for extended periods of time. We also find that an incentive for teams to tank exists, but that this incentive decreases (i) as uncertainty in the ability to determine quality players in the draft increases, (ii) as the number of teams in the league reduces, (iii) as team size decreases, and (iv) as the number of teams adopting a tanking strategy increases. Simulation models can be used to explore complex stochastic dynamic systems such as sports leagues, where managers face difficult decisions regarding the structure of their league and the desire to maintain competitive balance. PMID:24312243
Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.; Campbell, James A.
1999-06-01
In this research program, Pacific Northwest National Laboratory (PNNL) and Florida State University (FSU) are investigating the speciation of strontium and americium/curium in the presence of selected organic chelating agents (ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl) aethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), and iminodiacetic acid (IDA)) over ranges of hydroxide, carbonate, ionic strength, and competing metal ion concentrations present in high-level waste tanks. The project is composed of integrated research tasks that approach the problem of chemical speciation using macroscopic thermodynamic measurements of metal-ligand competition reactions, molecular modeling studies to identify structures or complexes of unusual stability, and mass spectrometry measurements of complex charge/mass ratio that can be applied to mixed metal-chelate systems. This fundamental information is then used to develop thermodynamic models, which allow the prediction of changes in chemical speciation and solubility that can occur in response to changes in tank processing conditions. In this way, we can develop new approaches that address fundamental problems in aqueous speciation and at the same time provide useful and practical information needed for tank processing.
NASA Technical Reports Server (NTRS)
Olson, Roland E; Land, Norman S
1943-01-01
Report presents the results of tests of longitudinal stability characteristics of models of several flying boats conducted in the NACA Tank No. 1. These investigations were made for the purpose of (1) determining suitable methods for evaluating the stability characteristics of models of flying boats, and (2) determining the design parameters which have an important effect on the porpoising. This report is mainly concerned with the construction of suitable models, the apparatus, and methods used in the tests. The effect of changes in some design parameters is discussed.
Design of cryogenic tanks for space vehicles shell structures analytical modeling
NASA Technical Reports Server (NTRS)
Copper, Charles; Mccarthy, K.; Pilkey, W. D.; Haviland, J. K.
1991-01-01
The initial objective was to study the use of superplastically formed corrugated hat section stringers and frames in place of integrally machined stringers over separate frames for the tanks of large launch vehicles subjected to high buckling loads. The ALS was used as an example. The objective of the follow-on project was to study methods of designing shell structures subjected to severe combinations of structural loads and thermal gradients, with emphasis on new combinations of structural arrangements and materials. Typical applications would be to fuselage sections of high speed civil transports and to cryogenic tanks on the National Aerospace Plane.
Temperature and flow measurements on near-freezing aviation fuels in a wing-tank model
NASA Technical Reports Server (NTRS)
Friedman, R.; Stockemer, F. J.
1980-01-01
Freezing behavior, pumpability, and temperature profiles for aviation turbine fuels were measured in a 190-liter tank, to simulate internal temperature gradients encountered in commercial airplane wing tanks. Two low-temperature situations were observed. Where the bulk of the fuel is above the specification freezing point, pumpout of the fuel removes all fuel except a layer adhering to the bottom chilled surfaces, and the unpumpable fraction depends on the fuel temperature near these surfaces. Where the bulk of the fuel is at or below the freezing point, pumpout ceases when solids block the pump inlet, and the unpumpable fraction depends on the overall average temperature.
Temperature and flow measurements on near-freezing aviation fuels in a wing-tank model
NASA Technical Reports Server (NTRS)
Friedman, R.; Stockemer, F. J.
1980-01-01
Freezing behavior, pumpability, and temperature profiles for aviation turbine fuels were measured in a 190-liter tank chilled to simulate internal temperature gradients encountered in commercial airplane wing tanks. When the bulk of the fuel was above the specification freezing point, pumpout of the fuel removed all fuel except a layer adhering to the bottom chilled surfaces, and the unpumpable fraction depended on the fuel temperature near these surfaces. When the bulk of the fuel was at or below the freezing point, pumpout ceased when solids blocked the pump inlet, and the unpumpable fraction depended on the overall average temperature.
Experimental Study of Low Temperature Behavior of Aviation Turbine Fuels in a Wing Tank Model
NASA Technical Reports Server (NTRS)
Stockemer, Francis J.
1979-01-01
An experimental investigation was performed to study aircraft fuels at low temperatures near the freezing point. The objective was an improved understanding of the flowability and pumpability of the fuels under conditions encoutered during cold weather flight of a long range commercial aircraft. The test tank simulated a section of an outer wing tank and was chilled on the upper and lower surfaces. Fuels included commercial Jet A and Diesel D-2; JP-5 from oil shale; and Jet A, intermediate freeze point, and D-2 fuels derived from selected paraffinic and naphthenic crudes. A pour point depressant was tested.
NASA Astrophysics Data System (ADS)
Azcona, José; Bouchotrouch, Faisal; González, Marta; Garciandía, Joseba; Munduate, Xabier; Kelberlau, Felix; Nygaard, Tor A.
2014-06-01
Wave tank testing of scaled models is standard practice during the development of floating wind turbine platforms for the validation of the dynamics of conceptual designs. Reliable recreation of the dynamics of a full scale floating wind turbine by a scaled model in a basin requires the precise scaling of the masses and inertias and also the relevant forces and its frequencies acting on the system. The scaling of floating wind turbines based on the Froude number is customary for basin experiments. This method preserves the hydrodynamic similitude, but the resulting Reynolds number is much lower than in full scale. The aerodynamic loads on the rotor are therefore out of scale. Several approaches have been taken to deal with this issue, like using a tuned drag disk or redesigning the scaled rotor. This paper describes the implementation of an alternative method based on the use of a ducted fan located at the model tower top in the place of the rotor. The fan can introduce a variable force that represents the total wind thrust by the rotor. A system controls this force by varying the rpm, and a computer simulation of the full scale rotor provides the desired thrust to be introduced by the fan. This simulation considers the wind turbine control, gusts, turbulent wind, etc. The simulation is performed in synchronicity with the test and it is fed in real time by the displacements and velocities of the platform captured by the acquisition system. Thus, the simulation considers the displacements of the rotor within the wind field and the calculated thrust models the effect of the aerodynamic damping. The system is not able currently to match the effect of gyroscopic momentum. The method has been applied during a test campaign of a semisubmersible platform with full catenary mooring lines for a 6MW wind turbine in scale 1/40 at Ecole Centrale de Nantes. Several tests including pitch free decay under constant wind and combined wave and wind cases have been performed. Data
SCALE-MODEL STUDIES OF MIXING IN DRINKING WATER STORAGE TANKS
Storage tanks and reservoirs are commonly used in drinking water distribution systems to equalize pumping requirements and operating pressures, and to provide emergency water for fire-fighting and pumping outages. Poor mixing in these structures can create pockets of older water...
A General Tank Test of a Model of the Hull of the British Singapore IIC Flying Boat
NASA Technical Reports Server (NTRS)
Dawson, John R; Truscott, Starr
1936-01-01
A general test was made in the N.A.C.A. tank of a 1/12-size model of the hull of the British Singapore IIC flying boat loaned by the Director of Research, British Air Ministry. The results are given in charts and are compared with the results of tests of a model of an American flying-boat hull, the Sikorsky S-40. The Singapore hull has a greater hump resistance but a much lower high-speed resistance than the S-40.
NASA Astrophysics Data System (ADS)
Poonoosamy, Jenna; Kosakowski, Georg; Van Loon, Luc R.; Mäder, Urs
2015-06-01
In the context of testing reactive transport codes and their underlying conceptual models, a simple 2D reactive transport experiment was developed. The aim was to use simple chemistry and design a reproducible and fast to conduct experiment, which is flexible enough to include several process couplings: advective-diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. A small tank was filled with a reactive layer of strontium sulfate (SrSO4) of two different grain sizes, sandwiched between two layers of essentially non-reacting quartz sand (SiO2). A highly concentrated solution of barium chloride was injected to create an asymmetric flow field. Once the barium chloride reached the reactive layer, it forced the transformation of strontium sulfate into barium sulfate (BaSO4). Due to the higher molar volume of barium sulfate, its precipitation caused a decrease of porosity and lowered the permeability. Changes in the flow field were observed with help of dye tracer tests. The experiments were modelled using the reactive transport code OpenGeosys-GEM. Tests with non-reactive tracers performed prior to barium chloride injection, as well as the density-driven flow (due to the high concentration of barium chloride solution), could be well reproduced by the numerical model. To reproduce the mineral bulk transformation with time, two populations of strontium sulfate grains with different kinetic rates of dissolution were applied. However, a default porosity permeability relationship was unable to account for measured pressure changes. Post mortem analysis of the strontium sulfate reactive medium provided useful information on the chemical and structural changes occurring at the pore scale at the interface that were considered in our model to reproduce the pressure evolution with time.
Poonoosamy, Jenna; Kosakowski, Georg; Van Loon, Luc R; Mäder, Urs
2015-01-01
In the context of testing reactive transport codes and their underlying conceptual models, a simple 2D reactive transport experiment was developed. The aim was to use simple chemistry and design a reproducible and fast to conduct experiment, which is flexible enough to include several process couplings: advective-diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. A small tank was filled with a reactive layer of strontium sulfate (SrSO4) of two different grain sizes, sandwiched between two layers of essentially non-reacting quartz sand (SiO2). A highly concentrated solution of barium chloride was injected to create an asymmetric flow field. Once the barium chloride reached the reactive layer, it forced the transformation of strontium sulfate into barium sulfate (BaSO4). Due to the higher molar volume of barium sulfate, its precipitation caused a decrease of porosity and lowered the permeability. Changes in the flow field were observed with help of dye tracer tests. The experiments were modelled using the reactive transport code OpenGeosys-GEM. Tests with non-reactive tracers performed prior to barium chloride injection, as well as the density-driven flow (due to the high concentration of barium chloride solution), could be well reproduced by the numerical model. To reproduce the mineral bulk transformation with time, two populations of strontium sulfate grains with different kinetic rates of dissolution were applied. However, a default porosity permeability relationship was unable to account for measured pressure changes. Post mortem analysis of the strontium sulfate reactive medium provided useful information on the chemical and structural changes occurring at the pore scale at the interface that were considered in our model to reproduce the pressure evolution with time.
Sachse, Benjamin; Meinl, Walter; Glatt, Hansruedi; Monien, Bernhard H
2014-10-01
Furfuryl alcohol is a rodent carcinogen present in numerous foodstuffs. Sulfotransferases (SULTs) convert furfuryl alcohol into the DNA reactive and mutagenic 2-sulfoxymethylfuran. Sensitive techniques for the isotope-dilution ultra performance liquid chromatography-tandem mass spectrometry quantification of resulting DNA adducts, e.g. N (2)-((furan-2-yl)methyl)-2'-deoxyguanosine (N (2)-MF-dG), were developed. To better understand the contribution of specific SULT forms to the genotoxicity of furfuryl alcohol in vivo, we studied the tissue distribution of N (2)-MF-dG in different mouse models. Earlier mutagenicity studies with Salmonella typhimurium strains expressing different human and murine SULT forms indicated that human SULT1A1 and murine Sult1a1 and 1d1 catalyze furfuryl alcohol sulfo conjugation most effectively. Here, we used three mouse lines to study the bioactivation of furfuryl alcohol by murine SULTs, FVB/N wild-type (wt) mice and two genetically modified models lacking either murine Sult1a1 or Sult1d1. The animals received a single dose of furfuryl alcohol, and the levels of the DNA adducts were determined in liver, kidney, lung, colon and small intestine. The effect of Sult1d1 gene disruption on the genotoxicity of furfuryl alcohol was moderate and limited to kidney and small intestine. In contrast, the absence of functional Sult1a1 had a massive influence on the adduct levels, which were lowered by 33-73% in all tissues of the female Sult1a1 null mice compared with the wt animals. The detection of high N (2)-MF-dG levels in a humanized mouse line expressing hSULT1A1/1A2 instead of endogeneous Sult1a1 and Sult1d1 supports the hypothesis that furfuryl alcohol is converted to the mutagenic 2-sulfoxymethylfuran also in humans.
Numerical Modeling of Mixing of Chemically Reacting, Non-Newtonian Slurry for Tank Waste Retrieval
D.A. Yuen; Y. Onishi; J.R. Rustand; B.E. Wells; T.E. Michener; A.R. Felmy; D.S. Trent; A.A. Ten; C.A. Hier
2002-02-06
Fifty-four million gallons of wastes containing 180-million curies of radioactivity are stored in single (SSTs)- and double-shell underground tanks (DSTs) at the U.S. Department of Energy's Hanford Site in eastern Washington (Gephart and Lundgren 1997). They are a multiphase, multicomponent, high-ionic strength, and highly basic mixture of liquids, solids, and, in some cases, gases. Mixer pumps will be installed in twenty-eight 4,0000-m DSTs to stir radioactive sludge/saltcake and supernatant liquid (and possibly a solvent) so the waste can be retrieved from the tanks for subsequent treatment and disposal. During the retrieval operation, complex interactions occur between waste mixing, chemical reactions, and rheology. Thus, decisions made about waste retrieval must account for these complex interactions.
NASA Astrophysics Data System (ADS)
Oanta, Emil M.; Dascalescu, Anca-Elena; Sabau, Adrian
2016-12-01
The paper presents an original analytical model of the hydrodynamic loads applied on the half-bridge of a circular settling tank. The calculus domain is defined using analytical geometry and the calculus of the local dynamic pressure is based on the radius from the center of the settling tank to the current area, i.e. the relative velocity of the fluid and the depth where the current area is located, i.e. the density of the fluid. Calculus of the local drag forces uses the discrete frontal cross sectional areas of the submerged structure in contact with the fluid. In the last stage is performed the reduction of the local drag forces in the appropriate points belonging to the main beam. This class of loads is producing the flexure of the main beam in a horizontal plane and additional twisting moments along this structure. Taking into account the hydrodynamic loads, the results of the theoretical models, i.e. the analytical model and the finite element model, may have an increased accuracy.
AIR AND RADON PATHWAY MODELING FOR THE F AREA TANK FARM
Dixon, K.; Phifer, M.
2010-07-30
An air and radon pathways analysis was conducted for the F-Area Tank Farm (FTF) to estimate the flux of volatile radionuclides and radon at the ground surface due to residual waste remaining in the tanks following closure. This analysis was used as the basis to estimate the dose to the maximally exposed individual (MEI) for the air pathway per Curie (Ci) of each radionuclide remaining in the combined FTF waste tanks. For the air pathway analysis, several gaseous radionuclides were considered. These included carbon-14 (C-14), chlorine-36 (Cl-36), iodine-129 (I-129), selenium-79 (Se-79), antimony-125 (Sb-125), tin-126 (Sn-126), tritium (H-3), and technetium-99 (Tc-99). The dose to the MEI was estimated at the SRS Boundary during the 100 year institutional control period. For the 10,000 year post closure compliance period, the dose to the MEI was estimated at the 100 m compliance point. Additionally, the dose to the MEI was estimated at a seepage outcrop located 1600 m from the facility. For the radon pathway analysis, five parent radionuclides and their progeny were analyzed. These parent radionuclides included uranium-238 (U-238), plutonium-238 (Pu-238), uranium-234 (U-234), thorium-230 (Th-230), and radium-226 (Ra-226). The peak flux of radon-222 due to each parent radionuclide was estimated for the simulation period of 10,100 years.
Testing of Densified Liquid Hydrogen Stratification in a Scale Model Propellant Tank
NASA Technical Reports Server (NTRS)
Greene, W. D.
1999-01-01
Propellant densification has been identified as a critical technology in the development of a single stage to orbit (SSTO) launch vehicle. The densification of cryogenic propellant through sub-cooling allows more propellant to be stored in a given volume. This allows for higher propellant mass fractions than would otherwise be possible with conventional, normal boiling point, cryogenic fluids. One critical step in determining the viability of densified propellant technology for launch vehicles is to perform the sequential process necessary to load a propellant tank with densified propellants. This paper describes a test program that was conducted at NASA to demonstrate the ability to load densified LH2 into a sub-scale propellant rank. This work was done through a collaborative effort between NASA Lewis Research Center and the Lockheed Martin Michoud Space Systems (LMMSS). The tank, is made from composite materials similar to that to be used on X-33, is formed from two lobes with a center seprum. Test results are shown for data that was collected on filling the sub-scale tank with densified liquid hydrogen propellant that was produced at the NASA Plum Brook Station. Data is compared to analytical predictions.
NASA Astrophysics Data System (ADS)
Argyropoulos, C. D.; Sideris, G. M.; Christolis, M. N.; Nivolianitou, Z.; Markatos, N. C.
2010-02-01
Petrochemical industries normally use storage tanks containing large amounts of flammable and hazardous substances. Therefore, the occurrence of a tank fire, such as the large industrial accident on 11th December 2005 at Buncefield Oil Storage Depots, is possible and usually leads to fire and explosions. Experience has shown that the continuous production of black smoke from these fires due to the toxic gases from the combustion process, presents a potential environmental and health problem that is difficult to assess. The goals of the present effort are to estimate the height of the smoke plume, the ground-level concentrations of the toxic pollutants (smoke, SO 2, CO, PAHs, VOCs) and to characterize risk zones by comparing the ground-level concentrations with existing safety limits. For the application of the numerical procedure developed, an external floating-roof tank has been selected with dimensions of 85 m diameter and 20 m height. Results are presented and discussed. It is concluded that for all scenarios considered, the ground-level concentrations of smoke, SO 2, CO, PAHs and VOCs do not exceed the safety limit of IDLH and there are no "death zones" due to the pollutant concentrations.
Tank tests of two models of flying-boat hulls to determine the effect of ventilating the step
NASA Technical Reports Server (NTRS)
Dawson, John R
1937-01-01
The results of tests made in the N.A.C.A. tank on two models of flying-boat hulls to determine the effect of ventilating the step are given graphically. The step of N.A.C.A. model 11-C was ventilated in several different ways and it was found that the resistance of the normal form is not appreciably affected by artificial ventilation in any of the forms tried. Further tests made with the depth of the step of model 11-C reduced likewise show no appreciable effect on the resistance from ventilation of the step. Tests were made on a model of the hull of the Navy P3M-1 flying-boat hull both with and without ventilation of the step. It was found that the discontinuity which is obtained in the resistance curves of this model is eliminated by ventilating the step.
Tank Tests of a Model of a Flying-boat Hull Having a Longitudinally Concave Planing Bottom
NASA Technical Reports Server (NTRS)
Parkinson, J B
1935-01-01
The NACA model 11-B, which has a longitudinally concave planing bottom forward of the step, was tested over a wide range of loading. The results of the tests are presented as curves of resistance and trimming moment plotted against speed for various trim angles and as curves of resistance coefficient at best trim angle, and trimming-moment coefficient. The characteristics of the form at the optimum trim are compared with those of NACA model 11-C which has the same form with the exception of a planing bottom longitudinally straight near the step. Photographs of the models being towed in the tank are included for a comparison of the spray patterns. At the best angles of trim in each case model 11-B has lower resistance at high speeds, a higher maximum positive trimming moment near the hump speed, and a more favorable spray pattern than of model 11-C.
NASA Astrophysics Data System (ADS)
Torgersen, Thomas
2006-06-01
Multiple issues in hydrologic and environmental sciences are now squarely in the public focus and require both government and scientific study. Two facts also emerge: (1) The new approach being touted publicly for advancing the hydrologic and environmental sciences is the establishment of community-operated "big science" (observatories, think tanks, community models, and data repositories). (2) There have been important changes in the business of science over the last 20 years that make it important for the hydrologic and environmental sciences to demonstrate the "value" of public investment in hydrological and environmental science. Given that community-operated big science (observatories, think tanks, community models, and data repositories) could become operational, I argue that such big science should not mean a reduction in the importance of single-investigator science. Rather, specific linkages between the large-scale, team-built, community-operated big science and the single investigator should provide context data, observatory data, and systems models for a continuing stream of hypotheses by discipline-based, specialized research and a strong rationale for continued, single-PI ("discovery-based") research. I also argue that big science can be managed to provide a better means of demonstrating the value of public investment in the hydrologic and environmental sciences. Decisions regarding policy will still be political, but big science could provide an integration of the best scientific understanding as a guide for the best policy.
Santoro, Domenico; Crapulli, Ferdinando; Raisee, Mehrdad; Raspa, Giuseppe; Haas, Charles N
2015-06-16
Wastewater disinfection processes are typically designed according to heuristics derived from batch experiments in which the interaction among wastewater quality, reactor hydraulics, and inactivation kinetics is often neglected. In this paper, a computational fluid dynamics (CFD) study was conducted in a nondeterministic (ND) modeling framework to predict the Escherichia coli inactivation by peracetic acid (PAA) in municipal contact tanks fed by secondary settled wastewater effluent. The extent and variability associated with the observed inactivation kinetics were both satisfactorily predicted by the stochastic inactivation model at a 95% confidence level. Moreover, it was found that (a) the process variability induced by reactor hydraulics is negligible when compared to the one caused by inactivation kinetics, (b) the PAA dose required for meeting regulations is dictated equally by the fixed limit of the microbial concentration as well as its probability of occurrence, and (c) neglecting the probability of occurrence during process sizing could lead to an underestimation of the PAA dose required by as much as 100%. Finally, the ND-CFD model was used to generate sizing information in the form of probabilistic disinfection curves relating E. coli inactivation and probability of occurrence with the average PAA dose and PAA residual concentration at the outlet of the contact tank.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-11-23
... has determined that, instead of Sec. 25.981(a)(3), alternative fuel tank structural lighting..., Alternative Fuel Tank Structural Lightning Protection Requirements, either have the common dictionary meaning... average probability per flight hour of the order of 1 x 10 -9 or less. 2. Alternative Fuel Tank...
Wagner, Richard William; Burkhard, James Frank; Dauer, Kenneth John
1999-11-16
A dual tank fuel system has primary and secondary fuel tanks, with the primary tank including a filler pipe to receive fuel and a discharge line to deliver fuel to an engine, and with a balance pipe interconnecting the primary tank and the secondary tank. The balance pipe opens close to the bottom of each tank to direct fuel from the primary tank to the secondary tank as the primary tank is filled, and to direct fuel from the secondary tank to the primary tank as fuel is discharged from the primary tank through the discharge line. A vent line has branches connected to each tank to direct fuel vapor from the tanks as the tanks are filled, and to admit air to the tanks as fuel is delivered to the engine.
NASA Astrophysics Data System (ADS)
Petropoulos, G. P.; North, M. R.; Ireland, G.; Srivastava, P. K.; Rendall, D. V.
2015-03-01
This paper describes the validation of the SimSphere SVAT model conducted at different ecosystem types in the USA and Australia. Specific focus was given to examining the models' ability in predicting Shortwave Incoming Solar Radiation (Rg), Net Radiation (Rnet), Latent Heat (LE), Sensible Heat (H), Air Temperature at 1.3 m (Tair 1.3 m) and Air Temperature at 50 m (Tair 50 m). Model predictions were compared against corresponding in situ measurements acquired for a total of 72 selected days of the year 2011 obtained from 8 sites belonging to the AmeriFlux (USA) and OzFlux (Australia) monitoring networks. Selected sites were representative of a variety of environmental, biome and climatic conditions, to allow for the inclusion of contrasting conditions in the model evaluation. The application of the model confirmed its high capability in representing the multifarious and complex interactions of the Earth system. Comparisons showed a good agreement between modelled and measured fluxes, especially for the days with smoothed daily flux trends. A good to excellent agreement between the model predictions and the in situ measurements was reported, particularly so for the LE, H, T1.3 m and T 50 m parameters (RMSD = 39.47, 55.06 W m-2, 3.23, 3.77 °C respectively). A systematic underestimation of Rg and Rnet (RMSD = 67.83, 58.69 W m-2, MBE = 67.83, 58.69 W m-2 respectively) was also found. Highest simulation accuracies were obtained for the open woodland savannah and mulga woodland sites for most of the compared parameters. Very high values of the Nash-Sutcliffe efficiency index were also reported for all parameters ranging from 0.720 to 0.998, suggesting a very good model representation of the observations. To our knowledge, this study presents the first comprehensive validation of SimSphere, particularly so in USA and Australian ecosystem types. Findings are important and timely, given the rapidly expanding use of this model worldwide both as an educational and research
NASA Astrophysics Data System (ADS)
Porta, L.; Illangasekare, T. H.; Loden, P.; Liptak, D.; Han, Q.; Jayasumana, A. P.
2006-12-01
The current practice for monitoring of subsurface plumes involves the collection of water samples from monitoring wells and laboratory analysis to determine concentrations. This data is used to make decisions for site management and in modeling. Cost and time constraints limit the number of samples and this approach becomes impractical for continuous monitoring of large, transient plumes. With the development of new sensor technologies and wireless sensor networks (WSNs), the potential exists to develop new and efficient subsurface data collection and monitoring methods. The goal is to automatically collect data from the sensors and wirelessly transmit the data to computer platforms where inversion codes and forward simulation models reside. This data can then be used to continuously monitor and update model parameters for the prediction of plume behavior. Many technological and operational challenges related to sensor placement and distribution, automation of real-time data collection, wireless communication, and modeling have to be overcome before the field implementation of complex plume monitoring systems. This preliminary proof of concept demonstration study assesses this technology using a physical aquifer test bed constructed in an intermediate scale tank. The test system includes a set of ten conductivity probes individually connected to wireless sensor boards (motes). The tank was packed using five well-characterized silica sands to represent a heterogeneous aquifer. Bromide tracer was continuously injected into a steady flow field and concentration at different points in the tank was measured with ten calibrated soil moisture/electrical conductivity sensors attached to six different motes. The motes in turn are connected to a computer for data analysis and coupled to models simulating flow and transport. The accuracy of the sensor-measured concentrations was tested against traditional grab samples analyzed using an ion chromatograph. Inverse modeling will
Technology Transfer Automated Retrieval System (TEKTRAN)
One of the major problems in watershed hydrology is to accurately simulate the transport of water and sediment from their sources to the watershed outlet. Current numerical models have been extensively used to determine upland erosion, but their application is primarily limited to the field/hillslop...
NASA Astrophysics Data System (ADS)
Dimitriadis, Panayiotis; Tegos, Aristoteles; Oikonomou, Athanasios; Pagana, Vassiliki; Koukouvinos, Antonios; Mamassis, Nikos; Koutsoyiannis, Demetris; Efstratiadis, Andreas
2016-03-01
One-dimensional and quasi-two-dimensional hydraulic freeware models (HEC-RAS, LISFLOOD-FP and FLO-2d) are widely used for flood inundation mapping. These models are tested on a benchmark test with a mixed rectangular-triangular channel cross section. Using a Monte-Carlo approach, we employ extended sensitivity analysis by simultaneously varying the input discharge, longitudinal and lateral gradients and roughness coefficients, as well as the grid cell size. Based on statistical analysis of three output variables of interest, i.e. water depths at the inflow and outflow locations and total flood volume, we investigate the uncertainty enclosed in different model configurations and flow conditions, without the influence of errors and other assumptions on topography, channel geometry and boundary conditions. Moreover, we estimate the uncertainty associated to each input variable and we compare it to the overall one. The outcomes of the benchmark analysis are further highlighted by applying the three models to real-world flood propagation problems, in the context of two challenging case studies in Greece.
Xiong, J.; Subramaniam, S.; Govindjee
1996-01-01
A three-dimensional model of the photosystem II (PSII) reaction center from the cyanobacterium Synechocystis sp. PCC 6803 was generated based on homology with the anoxygenic purple bacterial photosynthetic reaction centers of Rhodobacter sphaeroides and Rhodopseudomonas viridis, for which the X-ray crystallographic structures are available. The model was constructed with an alignment of D1 and D2 sequences with the L and M subunits of the bacterial reaction center, respectively, and by using as a scaffold the structurally conserved regions (SCRs) from bacterial templates. The structurally variant regions were built using a novel sequence-specific approach of searching for the best-matched protein segments in the Protein Data Bank with the "basic local alignment search tool" (Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ, 1990, J Mol Biol 215:403-410), and imposing the matching conformational preference on the corresponding D1 and D2 regions. The structure thus obtained was refined by energy minimization. The modeled D1 and D2 proteins contain five transmembrane alpha-helices each, with cofactors (4 chlorophylls, 2 pheophytins, 2 plastoquinones, and a non-heme iron) essential for PSII primary photochemistry embedded in them. A beta-carotene, considered important for PSII photoprotection, was also included in the model. Four different possible conformations of the primary electron donor P680 chlorophylls were proposed, one based on the homology with the bacterial template and the other three on existing experimental suggestions in literature. The P680 conformation based on homology was preferred because it has the lowest energy. Redox active tyrosine residues important for P680+ reduction as well as residues important for PSII cofactor binding were analyzed. Residues involved in interprotein interactions in the model were also identified. Herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was also modeled in the plastoquinone QB binding niche using the
1996-04-03
mobility , sophisticated communications, enhanced target acquisition, lethal firepower, and effective armor protection. In combi- nation, these factors...including the platoon’s individual tank crews and OPs; the effects of terrain, weather, and movement; and the ranges of all available platoon...dismounted soldiers with automatic weapons. Likewise, enemy activity can range from an entrenched force using prepared fighting positions to a unit
ERIC Educational Resources Information Center
Governick, Heather; Wellington, Thom
1998-01-01
Examines the options for upgrading, replacing, and removal or closure of underground storage tanks (UST). Reveals the diverse regulatory control involving USTs, the Environmental Protection Agency's interest in pursuing violators, and stresses the need for administrators to be knowledgeable about state and local agency definitions of regulated…
NASA Technical Reports Server (NTRS)
Klimas, A. J.
1983-01-01
A numerical method is presented for studying one-dimensional electron plasma evolution under typical interplanetary conditions. The method applies the Fourier-Fourier transform approach to a plasma model that is a generalization of the electrostatic Vlasov-Poisson system of equations. Conservation laws that are modified to include the plasma model generalization and also the boundary effects of nonperiodic solutions are given. A new conservation law for entropy in the transformed space is then introduced. These conservation laws are used to verify the numerical solutions. A discretization error analysis is presented. Two numerical instabilities and the methods used for their suppression are treated. It is shown that in interplanetary plasma conditions, the bump-on-tail instability produces significant excitation of plasma oscillations at the Bohm-Gross frequency and its second harmonic. An explanation of the second harmonic excitation is given in terms of wave-wave coupling during the growth phase of the instability.
The Continued Need for Modeling and Scaled Testing to Advance the Hanford Tank Waste Mission
Peurrung, Loni M.; Fort, James A.; Rector, David R.
2013-09-03
Hanford tank wastes are chemically complex slurries of liquids and solids that can exhibit changes in rheological behavior during retrieval and processing. The Hanford Waste Treatment and Immobilization Plant (WTP) recently abandoned its planned approach to use computational fluid dynamics (CFD) supported by testing at less than full scale to verify the design of vessels that process these wastes within the plant. The commercial CFD tool selected was deemed too difficult to validate to the degree necessary for use in the design of a nuclear facility. Alternative, but somewhat immature, CFD tools are available that can simulate multiphase flow of non-Newtonian fluids. Yet both CFD and scaled testing can play an important role in advancing the Hanford tank waste mission—in supporting the new verification approach, which is to conduct testing in actual plant vessels; in supporting waste feed delivery, where scaled testing is ongoing; as a fallback approach to design verification if the Full Scale Vessel Testing Program is deemed too costly and time-consuming; to troubleshoot problems during commissioning and operation of the plant; and to evaluate the effects of any proposed changes in operating conditions in the future to optimize plant performance.
Kim, Jae Heon; Shim, Ji Sung; Kang, Seung Chul; Shim, Kang Soo; Park, Jae Young; Moon, Du Geon; Lee, Jeong Gu
2011-01-01
Purpose Antagonists of α1-adrenergic receptors (α1ARs) relax prostate smooth muscle and relieve voiding and storage symptoms. Recently, increased expression of α1ARs with change of its subtype expression has been proved in bladder outlet obstruction (BOO). To search for the evidence of changes in α1ARs subtype expression and activity in the peripheral and spinal routes, the effects of spinal and peripheral administration of tamsulosin (an α1A/D-selective AR), naftopidil (an α1A/D-selective AR), and doxazosin (non-selective AR) on bladder activity were investigated in a rat model with or without BOO. Methods A total of 65 female Sprague-Dawley rats were divided into the BOO surgery group (n=47) and the sham surgery group (n=18). After 6 weeks, cystometry was assessed before and after intrathecal and intra-arterial administrations of tamsulosin, naftopidil, and doxazosin. Results After intra-arterial administrations of all three drugs, bladder capacity (BC) was increased and maximal intravesical pressure (Pmax) was decreased in both BOO and the sham rat models (P<0.05). After intrathecal administration of all three drugs, BC was increased and Pmax was decreased in only the BOO group. The episodes of involuntary contraction in the BOO rat models were decreased by intra-arterial administration (P=0.031). The increase of BC after intrathercal and intra-arterial administrations of α1ARs was significantly greater in the BOO group than in the sham group (P=0.023, P=0.041). In the BOO group, the increase of BC and decrease in Pmax were greater by intra-arterial administration than by intrathecal administration (P=0.035). There were no significant differences of the degrees of changes in the cystometric parameters among the three different α1ARs. Conclusions Up-regulations of the α1ARs in BOO were observed by the greater increases of BC after α1AR antagonist administrations in the BOO group than in the sham group. However, there were no subtype differences of the
NASA Astrophysics Data System (ADS)
Xu, G.; Larson, B. I.; Bemis, K. G.; Lilley, Marvin D.
2017-01-01
Tidal oscillations of venting temperature and chlorinity have been observed in the long-term time series data recorded by the Benthic and Resistivity Sensors (BARS) at the Grotto mound on the Juan de Fuca Ridge. In this study, we use a one-dimensional two-layer poroelastic model to conduct a preliminary investigation of three hypothetical scenarios in which seafloor tidal loading can modulate the venting temperature and chlorinity at Grotto through the mechanisms of subsurface tidal mixing and/or subsurface tidal pumping. For the first scenario, our results demonstrate that it is unlikely for subsurface tidal mixing to cause coupled tidal oscillations in venting temperature and chlorinity of the observed amplitudes. For the second scenario, the model results suggest that it is plausible that the tidal oscillations in venting temperature and chlorinity are decoupled with the former caused by subsurface tidal pumping and the latter caused by subsurface tidal mixing, although the mixing depth is not well constrained. For the third scenario, our results suggest that it is plausible for subsurface tidal pumping to cause coupled tidal oscillations in venting temperature and chlorinity. In this case, the observed tidal phase lag between venting temperature and chlorinity is close to the poroelastic model prediction if brine storage occurs throughout the upflow zone under the premise that layers 2A and 2B have similar crustal permeabilities. However, the predicted phase lag is poorly constrained if brine storage is limited to layer 2B as would be expected when its crustal permeability is much smaller than that of layer 2A.
NASA Astrophysics Data System (ADS)
Ibánhez, J. Severino P.; Leote, Catarina; Rocha, Carlos
2013-11-01
The role of benthic sandy ecosystems in mitigating NO3- loads carried by Submarine Groundwater Discharge (SGD) to coastal marine ecosystems is uncertain. Benthic biogeochemical mediation of NO3--rich submarine groundwater discharge was studied at the seepage face of a barrier island site in the Ria Formosa coastal lagoon (Southern Portugal). Preliminary analysis of NO3- porewater distributions at the seepage face during discharge indicated that benthic biogeochemical processes could significantly affect the fluxes of groundwater-borne NO3- into the lagoon. In order to discriminate between the relative contribution of transport and reaction processes to shape and concentration range evidenced by in-situ porewater NO3- gradients, an advection-dispersion-reaction (ADR) model of NO3- diagenesis was applied to describe NO3- porewater profiles obtained in March, June, September and December 2006. Good agreement between modeled and measured profiles was obtained. Model-derived apparent benthic nitrification and NO3- reduction rates ranged from 0.01 to 5.2 mmol m-2 h-1, sufficient to explain gross observed changes in NO3- fluxes arriving at the seepage face (up to 70% within the surficial 20 cm depth layer). Results of the analysis indicated that the upper limit of the seepage face promoted mitigation of NO3- fluxes to the lagoon throughout the year. In contrast, the lower limit of the seepage area promoted net amplification of the NO3- fluxes into the lagoon in June and September. These results will help constrain further work aiming to clarify the role of permeable sediments in mitigating nitrogen loading of coastal ecosystems.
NASA Astrophysics Data System (ADS)
Jang, Hangilro; Kim, Hee Joon
2015-12-01
In transient electromagnetic (TEM) measurements, secondary fields that contain information on conductive targets such as hydrothermal mineral deposits in the seafloor can be measured in the absence of strong primary fields. A TEM system using a loop source is useful to the development of compact, autonomous instruments, which are well suited to submersible-based surveys. In this paper, we investigate the possibility of applying an in-loop TEM system to the detection of marine hydrothermal deposits through a one-dimensional modeling and inversion study. We examine step-off responses for a layered model and compare the characteristics of horizontal and vertical loop systems for detecting hydrothermal deposits. The feasibility study shows that TEM responses are very sensitive to a highly conductive layer. Time-domain target responses are larger and appear earlier in horizontal magnetic fields than in vertical ones, although the vertical field has 2-3 times larger magnitude than the horizontal one. An inverse problem is formulated with the Gauss-Newton method and solved with the damped and smoothness-constrained least-squares approach. The test example for a marine hydrothermal TEM survey demonstrated that the depth extent, conductivity and thickness of the highly conductive layer are well resolved.
NASA Astrophysics Data System (ADS)
Tessitore, S.; Fernández-Merodo, J. A.; Herrera, G.; Tomás, R.; Ramondini, M.; Sanabria, M.; Duro, J.; Mulas, J.; Calcaterra, D.
2015-11-01
Subsidence is a hazard that may have natural or anthropogenic origin causing important economic losses. The area of Murcia city (SE Spain) has been affected by subsidence due to groundwater overexploitation since the year 1992. The main observed historical piezometric level declines occurred in the periods 1982-1984, 1992-1995 and 2004-2008 and showed a close correlation with the temporal evolution of ground displacements. Since 2008, the pressure recovery in the aquifer has led to an uplift of the ground surface that has been detected by the extensometers. In the present work an elastic hydro-mechanical finite element code has been used to compute the subsidence time series for 24 geotechnical boreholes, prescribing the measured groundwater table evolution. The achieved results have been compared with the displacements estimated through an advanced DInSAR technique and measured by the extensometers. These spatio-temporal comparisons have showed that, in spite of the limited geomechanical data available, the model has turned out to satisfactorily reproduce the subsidence phenomenon affecting Murcia City. The model will allow the prediction of future induced deformations and the consequences of any piezometric level variation in the study area.
Jayakar, Shilpa S; Singhal, Rekha S
2013-08-01
Scale up studies for production of lipoic acid (LA) from Saccharomyces cerevisiae have been reported in this paper for the first time. LA production in batch mode was carried out in a stirred tank bioreactor at varying agitation and aeration with maximum LA production of 512 mg/L obtained at 350 rpm and 25 % dissolved oxygen in batch culture conditions. Thus, LA production increased from 352 mg/L in shake flask to 512 mg/L in batch mode in a 5 L stirred tank bioreactor. Biomass production under these conditions was mathematically explained using logistic equation and data obtained for LA production and substrate utilization were successfully fitted using Luedeking-Piret and Mercier's models. The kinetic studies showed LA production to be growth associated. Further enhancement of LA production was carried out using fed-batch (variable volume) and semi-continuous modes of fermentation. Semi-continuous fermentation with three feeding cycles of sucrose effectively increased the production of LA from 512 to 725 mg/L.
NASA Astrophysics Data System (ADS)
Woody, M. C.; Wong, H.-W.; West, J. J.; Arunachalam, S.
2016-12-01
Aviation activities represent an important and unique mode of transportation, but also impact air quality. In this study, we aim to quantify the impact of aircraft on air quality, focusing on aviation-attributable PM2.5 at scales ranging from local (a few kilometers) to continental (spanning hundreds of kilometers) using the Community Multiscale Air Quality-Advanced Plume Treatment (CMAQ-APT) model. In our CMAQ-APT simulations, a plume scale treatment is applied to aircraft emissions from 99 major U.S. airports over the contiguous U.S. in January and July 2005. In addition to the plume scale treatment, we account for the formation of non-traditional secondary organic aerosols (NTSOA) from the oxidation of semivolatile and intermediate volatility organic compounds (S/IVOCs) emitted from aircraft, and utilize alternative emission estimates from the Aerosol Dynamics Simulation Code (ADSC). ADSC is a 1-D plume scale model that estimates engine specific PM and S/IVOC emissions at ambient conditions, accounting for relative humidity and temperature. We estimated monthly and contiguous U.S. average aviation-attributable PM2.5 to be 2.7 ng m-3 in January and 2.6 ng m-3 in July using CMAQ-APT with ADSC emissions. This represents an increase of 40% and 12% in January and July, respectively, over impacts using traditional modeling approaches (traditional emissions without APT). The maximum fine scale (subgrid scale) hourly impacts at a major airport were 133.6 μg m-3 in January and 165.4 μg m-3 in July, considerably higher than the maximum grid-based impacts at the airport of 4.3 μg m-3 in January and 0.5 μg m-3 in July.
Roy, Prasanta; Roy, Binoy Krishna
2016-07-01
The Quadruple Tank Process (QTP) is a well-known benchmark of a nonlinear coupled complex MIMO process having both minimum and nonminimum phase characteristics. This paper presents a novel self tuning type Dual Mode Adaptive Fractional Order PI controller along with an Adaptive Feedforward controller for the QTP. The controllers are designed based on a novel Variable Parameter Transfer Function model. The effectiveness of the proposed model and controllers is tested through numerical simulation and experimentation. Results reveal that the proposed controllers work successfully to track the reference signals in all ranges of output. A brief comparison with some of the earlier reported similar works is presented to show that the proposed control scheme has some advantages and better performances than several other similar works.
NASA Astrophysics Data System (ADS)
Toyota, K.; Dastoor, A. P.; Ryzhkov, A.
2014-04-01
Atmospheric mercury depletion events (AMDEs) refer to a recurring depletion of mercury occurring in the springtime Arctic (and Antarctic) boundary layer, in general, concurrently with ozone depletion events (ODEs). To close some of the knowledge gaps in the physical and chemical mechanisms of AMDEs and ODEs, we have developed a one-dimensional model that simulates multiphase chemistry and transport of trace constituents throughout porous snowpack and in the overlying atmospheric boundary layer (ABL). This paper constitutes Part 2 of the study, describing the mercury component of the model and its application to the simulation of AMDEs. Building on model components reported in Part 1 ("In-snow bromine activation and its impact on ozone"), we have developed a chemical mechanism for the redox reactions of mercury in the gas and aqueous phases with temperature dependent reaction rates and equilibrium constants accounted for wherever possible. Thus the model allows us to study the chemical and physical processes taking place during ODEs and AMDEs within a single framework where two-way interactions between the snowpack and the atmosphere are simulated in a detailed, process-oriented manner. Model runs are conducted for meteorological and chemical conditions that represent the springtime Arctic ABL characterized by the presence of "haze" (sulfate aerosols) and the saline snowpack on sea ice. The oxidation of gaseous elemental mercury (GEM) is initiated via reaction with Br-atom to form HgBr, followed by competitions between its thermal decomposition and further reactions to give thermally stable Hg(II) products. To shed light on uncertain kinetics and mechanisms of this multi-step oxidation process, we have tested different combinations of their rate constants based on published laboratory and quantum mechanical studies. For some combinations of the rate constants, the model simulates roughly linear relationships between the gaseous mercury and ozone concentrations as
NASA Astrophysics Data System (ADS)
Toyota, K.; Dastoor, A. P.; Ryzhkov, A.
2013-08-01
Atmospheric mercury depletion events (AMDEs) refer to a recurring depletion of mercury in the springtime Arctic (and Antarctic) boundary layer, occurring, in general, concurrently with ozone depletion events (ODEs). To close some of the knowledge gaps in the physical and chemical mechanisms of AMDEs and ODEs, we have developed a one-dimensional model that simulates multiphase chemistry and transport of trace constituents throughout porous snowpack and in the overlying atmospheric boundary layer (ABL). Building on the model reported in a companion paper (Part 1: In-snow bromine activation and its impact on ozone), we have expanded the chemical mechanism to include the reactions of mercury in the gas- and aqueous-phases with temperature dependence of rate and equilibrium constants accounted for wherever possible. Thus the model allows us to study the chemical and physical processes taking place during ODEs and AMDEs within a single framework where two-way interactions between the snowpack and the atmosphere are simulated in a detailed, process-oriented manner. Model runs are conducted for meteorological and chemical conditions representing the springtime Arctic ABL loaded with "haze" sulfate aerosols and the underlying saline snowpack laid on sea ice. Using recent updates for the Hg + Br \\rightleftarrows HgBr reaction kinetics, we show that the rate and magnitude of photochemical loss of gaseous elemental mercury (GEM) during AMDEs exhibit a strong dependence on the choice of reaction(s) of HgBr subsequent to its formation. At 253 K, the temperature that is presumably low enough for bromine radical chemistry to cause prominent AMDEs as indicated from field observations, the parallel occurrence of AMDEs and ODEs is simulated if the reaction HgBr + BrO is assumed to produce a thermally stable intermediate, Hg(OBr)Br, at the same rate constant as the reaction HgBr + Br. On the contrary, the simulated depletion of atmospheric mercury is notably diminished by not
Tank 241-U-204 tank characterization plan
Bell, K.E.
1995-03-23
This document is the tank characterization plan for Tank 241-U-204 located in the 200 Area Tank Farm on the Hanford Reservation in Richland, Washington. This plan describes Data Quality Objectives (DQO) and presents historical information and scheduled sampling events for tank 241-U-204.
Dziarmaga, Jacek; Zurek, Wojciech H
2014-08-05
Kibble-Zurek mechanism (KZM) uses critical scaling to predict density of topological defects and other excitations created in second order phase transitions. We point out that simply inserting asymptotic critical exponents deduced from the immediate vicinity of the critical point to obtain predictions can lead to results that are inconsistent with a more careful KZM analysis based on causality - on the comparison of the relaxation time of the order parameter with the "time distance" from the critical point. As a result, scaling of quench-generated excitations with quench rates can exhibit behavior that is locally (i.e., in the neighborhood of any given quench rate) well approximated by the power law, but with exponents that depend on that rate, and that are quite different from the naive prediction based on the critical exponents relevant for asymptotically long quench times. Kosterlitz-Thouless scaling (that governs e.g. Mott insulator to superfluid transition in the Bose-Hubbard model in one dimension) is investigated as an example of this phenomenon.
NASA Astrophysics Data System (ADS)
Annewandter, R.; Kalinowksi, M. B.
2009-04-01
An underground nuclear explosion injects radionuclids in the surrounding host rock creating an initial radionuclid distribution. In the case of fractured permeable media, cyclical changes in atmospheric pressure can draw gaseous species upwards to the surface, establishing a ratcheting pump effect. The resulting advective transport is orders of magnitude more significant than transport by molecular diffusion. In the 1990s the US Department of Energy funded the socalled Non-Proliferation Experiment conducted by the Lawrence Livermore National Laboratory to investigate this barometric pumping effect for verifying compliance with respect to the Comprehensive Nuclear Test Ban Treaty. A chemical explosive of approximately 1 kt TNT-equivalent has been detonated in a cavity located 390 m deep in the Rainier Mesa (Nevada Test Site) in which two tracer gases were emplaced. Within this experiment SF6 was first detected in soil gas samples taken near fault zones after 50 days and 3He after 325 days. For this paper a locally one-dimensional dual-porosity model for flow along the fracture and within the permeable matrix was used after Nilson and Lie (1990). Seepage of gases and diffusion of tracers between fracture and matrix are accounted. The advective flow along the fracture and within the matrix block is based on the FRAM filtering remedy and methodology of Chapman. The resulting system of equations is solved by an implicit non-iterative algorithm. Results on time of arrival and subsurface concentration levels for the CTBT-relevant xenons will be presented.
1D-VAR Retrieval Using Superchannels
NASA Technical Reports Server (NTRS)
Liu, Xu; Zhou, Daniel; Larar, Allen; Smith, William L.; Schluessel, Peter; Mango, Stephen; SaintGermain, Karen
2008-01-01
Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.
De Schepper, W; Dries, J; Geuens, L; Blust, R
2010-07-01
The aim of this work is the Toxicity Identification Evaluation (TIE) of highly toxic tank truck cleaning wastewater effluent. Conventional TIE, using EDTA and activated carbon addition, revealed organic compounds as main source of toxicity. Additional toxicant characteristics could be derived from hydraulic wastewater treatment plant simulation being high intake frequency, low biodegradability and high acute toxicity ratio between Pseudokirchneriella subcapitata and Daphnia magna. The risk probability of compounds present in the influent wastewater was simulated using USEPA Estimation Program Interface (EPI) software. Compound toxicity, solubility and removal rate in a wastewater treatment plant were incorporated into one risk number indicative for the probability of a compound to cause toxicity in the effluent. The herbicide acetochlor was deducted from these TIE procedures as major toxicant and this was confirmed by chemical measurements, concentrations in the effluent samples ranged from 3.73+/-0.52 ppm to 7.8+/-2.1 ppm acetochlor equivalents.
NASA Astrophysics Data System (ADS)
Böhm, Michael C.
1984-03-01
The band structures of 11 one-dimensional (ID) poly-decker sandwich compounds with different transition metal centers M (M = Mn, Fe, Co, Ni, Cu, Zn) and a variety of fivemembered π ligands L from the cyclopentadienyl moiety (C5H5) to the pure boron ring B5H5 have been studied by means of a semiempirical crystal orbital procedure based on the INDO approximation in order to allow a priori predictions on possible semiconducting or conducting low-dimensional materials composed by ML fragments. To determine the (numerically) different selfenergy corrections (i.e. long-range and short-range "correlations") in the transition metal 3d spines and the ligand backbones approximate quasi-particle shifts have been employed for the correction of the Hartree-Fock (HF) band energies. The band structure properties (e.g., dispersion curves, density of states distributions, effective mass parameters, propagation times of charge carriers) are discussed in the light of the semiempirical tight-binding approach. It is shown that the forbidden band gaps are reduced with an increasing number of B atoms in the π ligands. The gap in the Mn(C5H5) stack amounts to 8.27 eV, while overlapping dispersion curves are predicted in the Zn(B5H5) derivative. This model polymer is the only intrinsic conductor in the series of the studied ID metallocenes; all other compounds require injected charge carriers (electrons or holes) in order to achieve partially filled bands. Injected holes in the Mn or Fe backbones lead to ID materials with conducting 3d spines; the charge transfer in this regime is best described as some type of hopping motion. The remaining poly-decker strands belong to the class of organic metals (injected carriers) with conductive pathways that are formed by diffuse ligand states leading to transfer processes that can be rationalized in terms of a band picture. The rotational profiles and the magnitudes of intracell and intercell interactions are also studied. The band
Park, In-Hyeok; Lee, Jeong-Yong; Lee, Ji-Heon; Ha, Sung-Ryong
2014-01-01
Currently, unprecedented levels of damage arising from major weather events have been experienced in a number of major cities worldwide. Furthermore, the frequency and the scale of these disasters appear to be increasing and this is viewed by some as tangible proof of climate change. In the urbanized areas sewer overflows and resulting inundation are attributed to the conversion of previous surfaces into impervious surfaces, resulting in increased volumes of runoff which exceed the capacity of sewer systems and in particular combined sewer systems. In this study, the characteristics of sewer overflows and inundation have been analyzed in a repeatedly flooded zone in the city of Cheongju in Korea. This included an assessment of inundation in a 50-year storm event with total rainfall of 165 mm. A detailed XP-SWMM 2D model was assembled and run to simulate the interaction of the sewage system overflows and surface inundation to determine if inundation is due to hydraulic capacity limitations in the sewers or limitations in surface inlet capacities or a combination of both. Calibration was undertaken using observation at three locations (PT #1, PT #2, PT #3) within the study area. In the case of the subsurface flow calibration, R(2) value of 0.91 and 0.78 respectively were achieved at PT #1 and PT #2. Extremely good agreement between observed and predicted surface flow depths was achieved also at PT #1 and PT #2. However, at PT #3 the predicted flow depth was 4 cm lower than the observed depth, which was attributed to the impact of buildings on the local flow distribution. Areas subject to flooding were classified as either Type A (due to insufficient hydraulic capacity of a sewer), Type B (which is an area without flooding notwithstanding insufficient hydraulic capacity of a sewer) or Type C (due to inlet limitations, i.e. there is hydraulic capacity in a sewer which is not utilized). In the total flooded zone, 24% was classified as Type A (10.2 ha) and 25% was
Feed tank transfer requirements
Freeman-Pollard, J.R.
1998-09-16
This document presents a definition of tank turnover. Also, DOE and PC responsibilities; TWRS DST permitting requirements; TWRS Authorization Basis (AB) requirements; TWRS AP Tank Farm operational requirements; unreviewed safety question (USQ) requirements are presented for two cases (i.e., tank modifications occurring before tank turnover and tank modification occurring after tank turnover). Finally, records and reporting requirements, and documentation which will require revision in support of transferring a DST in AP Tank Farm to a privatization contractor are presented.
NASA Astrophysics Data System (ADS)
Grevemeyer, I.; Arroyo, I. G.
2015-12-01
Earthquake source locations are generally routinely constrained using a global 1-D Earth model. However, the source location might be associated with large uncertainties. This is definitively the case for earthquakes occurring at active continental margins were thin oceanic crust subducts below thick continental crust and hence large lateral changes in crustal thickness occur as a function of distance to the deep-sea trench. Here, we conducted a case study of the 2002 Mw 6.4 Osa thrust earthquake in Costa Rica that was followed by an aftershock sequence. Initial relocations indicated that the main shock occurred fairly trenchward of most large earthquakes along the Middle America Trench off central Costa Rica. The earthquake sequence occurred while a temporary network of ocean-bottom-hydrophones and land stations 80 km to the northwest were deployed. By adding readings from permanent Costa Rican stations, we obtain uncommon P wave coverage of a large subduction zone earthquake. We relocated this catalog using a nonlinear probabilistic approach using a 1-D and two 3-D P-wave velocity models. The 3-D model was either derived from 3-D tomography based on onshore stations and a priori model based on seismic refraction data. All epicentres occurred close to the trench axis, but depth estimates vary by several tens of kilometres. Based on the epicentres and constraints from seismic reflection data the main shock occurred 25 km from the trench and probably along the plate interface at 5-10 km depth. The source location that agreed best with the geology was based on the 3-D velocity model derived from a priori data. Aftershocks propagated downdip to the area of a 1999 Mw 6.9 sequence and partially overlapped it. The results indicate that underthrusting of the young and buoyant Cocos Ridge has created conditions for interpolate seismogenesis shallower and closer to the trench axis than elsewhere along the central Costa Rica margin.
NASA Technical Reports Server (NTRS)
1979-01-01
For NASA's Apollo program, McDonnell Douglas Astronautics Company, Huntington Beach, California, developed and built the S-IVB, uppermost stage of the three-stage Saturn V moonbooster. An important part of the development task was fabrication of a tank to contain liquid hydrogen fuel for the stage's rocket engine. The liquid hydrogen had to be contained at the supercold temperature of 423 degrees below zero Fahrenheit. The tank had to be perfectly insulated to keep engine or solar heat from reaching the fuel; if the hydrogen were permitted to warm up, it would have boiled off, or converted to gaseous form, reducing the amount of fuel available to the engine. McDonnell Douglas' answer was a supereffective insulation called 3D, which consisted of a one-inch thickness of polyurethane foam reinforced in three dimensions with fiberglass threads. Over a 13-year development and construction period, the company built 30 tanks and never experienced a failure. Now, after years of additional development, an advanced version of 3D is finding application as part of a containment system for transporting Liquefied Natural Gas (LNG) by ship.
A collection of the collapsed results of general tank tests of miscellaneous flying-boat-hull models
NASA Technical Reports Server (NTRS)
Locke, F W S , Jr
1947-01-01
Presented here are the summary charts of the collapsed results of general tank tests of about 100 flying boat hull models. These summary charts are intended to be used as an engineering tool to enable a flying boat designer to grasp more quickly the significance of various hull form parameters as they influence his particular airplane. The form in which the charts are prepared is discussed in some detail in order to make them clearer to the designer. This is a data report, and no attempt has been made to produce conclusions or correlations of the usual sort. However, some generalizations are put forward on the various methods in which summary charts may be used.
CHOPPIN, GREGORY R.
2003-06-01
The objective of this research project is to measure the effects of organic chelate complexation on the speciation and solubility of Sr and trivalent actinides under strongly basic, high carbonate conditions, similar to those present in high- level waste tanks at U.S. Department of Energy storage sites. We proposed, (1) extension to important chelates not previously studied; (2) studies of completing metal ions; and (3) specific studies using Am(III)/Cm(III). The chelate complexation studies would extend our previous research on EDTA, HEDTA, NTA, and IDA to citrate and oxalate. In addition, we propose to address the possible formation of mixed ligand- ligand complexes for Eu(III) in EDTA-HEDTA, EDTA-NTA, HEDTA-NTA, and ligand-carbonate solutions. The fundamental data on chemical speciation and solubility will be used to develop accurate thermodynamic models which are valid to high ionic strength.
A Complete Tank Test of a Model of a Flying-boat Hull - N.A.C.A. Model No.11-A
NASA Technical Reports Server (NTRS)
Parkinson, John B
1933-01-01
Model No. 11-A was designed as an improvement over N.A.C.A. Model No. 11, a complete test of which is described in N.A.C.A. Technical Note No. 464. In contrast with the longitudinal upward curvature in the planing bottom forward of the main step on Model 11-A was made as flat as practicable. Otherwise, the two models have very nearly the same form. The results of towing tests made on Model 11-A in the N.A.C.A. tank over a wide range of speed, load on the water, and trim angle are presented, both as original test data and as non dimensional coefficients. A comparison is made with similar results from the test of Model No. 11. The practical significance of the improvement obtained is demonstrated by applying the data from the new form to the illustrative design problem use in the note on Model NO. 11.
Popovic, Marta; Zaja, Roko; Fent, Karl; Smital, Tvrtko
2014-10-01
Polyspecific transporters from the organic anion transporting polypeptide (OATP/Oatp) superfamily mediate the uptake of a wide range of compounds. In zebrafish, Oatp1d1 transports conjugated steroid hormones and cortisol. It is predominantly expressed in the liver, brain and testes. In this study we have characterized the transport of xenobiotics by the zebrafish Oatp1d1 transporter. We developed a novel assay for assessing Oatp1d1 interactors using the fluorescent probe Lucifer yellow and transient transfection in HEK293 cells. Our data showed that numerous environmental contaminants interact with zebrafish Oatp1d1. Oatp1d1 mediated the transport of diclofenac with very high affinity, followed by high affinity towards perfluorooctanesulfonic acid (PFOS), nonylphenol, gemfibrozil and 17α-ethinylestradiol; moderate affinity towards carbaryl, diazinon and caffeine; and low affinity towards metolachlor. Importantly, many environmental chemicals acted as strong inhibitors of Oatp1d1. A strong inhibition of Oatp1d1 transport activity was found by perfluorooctanoic acid (PFOA), chlorpyrifos-methyl, estrone (E1) and 17β-estradiol (E2), followed by moderate to low inhibition by diethyl phthalate, bisphenol A, 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4 tetrahydronapthalene and clofibrate. In this study we identified Oatp1d1 as a first Solute Carrier (SLC) transporter involved in the transport of a wide range of xenobiotics in fish. Considering that Oatps in zebrafish have not been characterized before, our work on zebrafish Oatp1d1 offers important new insights on the understanding of uptake processes of environmental contaminants, and contributes to the better characterization of zebrafish as a model species. - Highlights: • We optimized a novel assay for determination of Oatp1d1 interactors • Oatp1d1 is the first SLC characterized fish xenobiotic transporter • PFOS, nonylphenol, diclofenac, EE2, caffeine are high affinity Oatp1d1substrates • PFOA, chlorpyrifos
40 CFR Table 5 to Subpart Vvvvvv... - Emission Limits and Compliance Requirements for Storage Tanks
Code of Federal Regulations, 2010 CFR
2010-07-01
... information specified above for Items 1.b., 1.c., 1.d, and