Science.gov

Sample records for 1-d photochemical model

  1. 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

  2. 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.

  3. Photochemical Modeling Applications

    EPA Pesticide Factsheets

    Provides access to modeling applications involving photochemical models, including modeling of ozone, particulate matter (PM), and mercury for national and regional EPA regulations such as the Clean Air Interstate Rule (CAIR) and the Clean Air Mercury Rule

  4. Photochemical and photocatalytic evaluation of 1D titanate/TiO2 based nanomaterials

    NASA Astrophysics Data System (ADS)

    Conceição, D. S.; Ferreira, D. P.; Graça, C. A. L.; Júlio, M. F.; Ilharco, L. M.; Velosa, A. C.; Santos, P. F.; Vieira Ferreira, L. F.

    2017-01-01

    One-dimensional (1D) titanate based nanomaterials were synthesized following an alkaline hydrothermal approach of commercial TiO2 nanopowder. The morphological features of all materials were monitored by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and also Brunauer-Emmett-Teller (BET) technique. In addition the photochemical behaviour of these nanostructured materials were evaluated with the use of laser induced luminescence (LIL), ground-state diffuse reflectance (GSDR), and laser-flash photolysis in diffuse reflectance mode (DRLFP). The mixed titanate/TiO2 nanowires presented the least intense fluorescence spectra, suggesting the presence of surficial defects that can extend the lifetime of the excited charge carriers. A fluorescent 'rhodamine-like' dye was adsorbed onto different materials and examined via photoexcitation in the visible range to study the self-photosensitization mechanism. The presence of the radical cation of the dye and the degradation kinetics, when compared with a neutral substrate-cellulose, provided significant evidences regarding the photoactivity of the different materials. Regarding all the materials under study, the nanowires exhibited a strong photocatalytic efficiency, for the adsorbed fluorescent probe. The photocatalytic mechanism was also considered by studying the photodegradation capability of the titanate based materials in the presence of an herbicide, Amicarbazone, after ultraviolet (UVA) photoexcitation.

  5. MNEQA, an emissions model for photochemical simulations

    NASA Astrophysics Data System (ADS)

    Ortega, S.; Soler, M. R.; Alarcón, M.; Arasa, R.

    This study focuses on a new emissions model, Numerical Emissions Model for Air Quality (MNEQA), to be used in photochemical simulations and emission control strategies relating to tropospheric ozone pollutants. MNEQA processes available local information from external files and is easily adaptable to any desired spatial resolution. Top-down and bottom-up methodologies are combined to calculate emissions at the required resolution for photochemical simulations. It was used in conjunction with the MM5-CMAQ air quality modelling system and was applied to an episode of high ozone levels in June 2003. Emission results are widely analysed showing a difference of -8.8% with EMEP NOx emissions, and -18.7% with EMEP VOC emissions. Related to ozone simulations, comparative results between measurements and simulations indicated good behaviour of the model in reproducing diurnal ozone concentrations, as statistical values fall within the EPA and EU regulatory frameworks.

  6. Photochemical Phenomenology Model for the New Millennium

    NASA Technical Reports Server (NTRS)

    Bishop, James; Evans, J. Scott

    2001-01-01

    The "Photochemical Phenomenology Model for the New Millennium" project tackles the issue of reengineering and extension of validated physics-based modeling capabilities ("legacy" computer codes) to application-oriented software for use in science and science-support activities. While the design and architecture layouts are in terms of general particle distributions involved in scattering, impact, and reactive interactions, initial Photochemical Phenomenology Modeling Tool (PPMT) implementations are aimed at construction and evaluation of photochemical transport models with rapid execution for use in remote sensing data analysis activities in distributed systems. Current focus is on the Composite Infrared Spectrometer (CIRS) data acquired during the CASSINI flyby of Jupiter. Overall, the project has stayed on the development track outlined in the Year 1 annual report and most Year 2 goals have been met. The issues that have required the most attention are: implementation of the core photochemistry algorithms; implementation of a functional Java Graphical User Interface; completion of a functional CORBA Component Model framework; and assessment of performance issues. Specific accomplishments and the difficulties encountered are summarized in this report. Work to be carried out in the next year center on: completion of testing of the initial operational implementation; its application to analysis of the CASSINI/CIRS Jovian flyby data; extension of the PPMT to incorporate additional phenomenology algorithms; and delivery of a mature operational implementation.

  7. Calibration of a 1D/1D urban flood model using 1D/2D model results in the absence of field data.

    PubMed

    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.

  8. Photochemical grid model implementation and application of ...

    EPA Pesticide Factsheets

    For the purposes of developing optimal emissions control strategies, efficient approaches are needed to identify the major sources or groups of sources that contribute to elevated ozone (O3) concentrations. Source-based apportionment techniques implemented in photochemical grid models track sources through the physical and chemical processes important to the formation and transport of air pollutants. Photochemical model source apportionment has been used to track source impacts of specific sources, groups of sources (sectors), sources in specific geographic areas, and stratospheric and lateral boundary inflow on O3. The implementation and application of a source apportionment technique for O3 and its precursors, nitrogen oxides (NOx) and volatile organic compounds (VOCs), for the Community Multiscale Air Quality (CMAQ) model are described here. The Integrated Source Apportionment Method (ISAM) O3 approach is a hybrid of source apportionment and source sensitivity in that O3 production is attributed to precursor sources based on O3 formation regime (e.g., for a NOx-sensitive regime, O3 is apportioned to participating NOx emissions). This implementation is illustrated by tracking multiple emissions source sectors and lateral boundary inflow. NOx, VOC, and O3 attribution to tracked sectors in the application are consistent with spatial and temporal patterns of precursor emissions. The O3 ISAM implementation is further evaluated through comparisons of apportioned am

  9. Brady 1D seismic velocity model ambient noise prelim

    SciTech Connect

    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.

  10. Effect of chemical kinetics uncertainties on calculated constituents in a tropospheric photochemical model

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Stewart, Richard W.

    1991-01-01

    Random photochemical reaction rates are employed in a 1D photochemical model to examine uncertainties in tropospheric concentrations and thereby determine critical kinetic processes and significant correlations. Monte Carlo computations are used to simulate different chemical environments and their related imprecisions. The most critical processes are the primary photodissociation of O3 (which initiates ozone destruction) and NO2 (which initiates ozone formation), and the OH/methane reaction is significant. Several correlations and anticorrelations between species are discussed, and the ozone/transient OH correlation is examined in detail. One important result of the modeling is that estimates of global OH are generally about 25 percent uncertain, limiting the precision of photochemical models. Techniques for reducing the imprecision are discussed which emphasize the use of species and radical species measurements.

  11. Photochemical Phenomenology Model for the New Millenium

    NASA Technical Reports Server (NTRS)

    Bishop, James; Evans, J. Scott

    2000-01-01

    This project tackles the problem of conversion of validated a priori physics-based modeling capabilities, specifically those relevant to the analysis and interpretation of planetary atmosphere observations, to application-oriented software for use in science and science-support activities. The software package under development, named the Photochemical Phenomenology Modeling Tool (PPMT), has particular focus on the atmospheric remote sensing data to be acquired by the CIRS instrument during the CASSINI Jupiter flyby and orbital tour of the Saturnian system. Overall, the project has followed the development outline given in the original proposal, and the Year 1 design and architecture goals have been met. Specific accomplishments and the difficulties encountered are summarized in this report. Most of the effort has gone into complete definition of the PPMT interfaces within the context of today's IT arena: adoption and adherence to the CORBA Component Model (CCM) has yielded a solid architecture basis, and CORBA-related issues (services, specification options, development plans, etc.) have been largely resolved. Implementation goals have been redirected somewhat so as to be more relevant to the upcoming CASSINI flyby of Jupiter, with focus now being more on data analysis and remote sensing retrieval applications.

  12. 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.

  13. Chemical kinetics and photochemical data for use in stratospheric modeling

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Margitan, J. J.; Molina, M. J.; Watson, R. T.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.

    1985-01-01

    Rate constants and photochemical cross sections are presented. The primary application of the data is for modeling of the stratospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena.

  14. GIS-BASED 1-D DIFFUSIVE WAVE OVERLAND FLOW MODEL

    SciTech Connect

    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.

  15. Promotion of nano-anatase TiO(2) on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach.

    PubMed

    Su, Mingyu; Liu, Huiting; Liu, Chao; Qu, Chunxiang; Zheng, Lei; Hong, Fashui

    2009-06-01

    Previous researches approved that photocatalysis activity of nano-TiO(2) could obviously increase photosynthetic effects of spinach, but the mechanism of improving light energy transfer and conversion is still unclear. In the present we investigated effects of nano-anatase TiO(2) on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach. Several effects of nano-anatase TiO(2) were observed: (1) UV-vis spectrum was blue shifted in both Soret and Q bands, and the absorption intensity was obviously increased; (2) resonance Raman spectrum showed four main peaks, which are ascribed to carotene, and the Raman peak intensity was as 6.98 times as that of the control; (3) the fluorescence emission peak was blue shifted and the intensity was decreased by 23.59%; (4) the DCPIP photoreduction activity showed 129.24% enhancement; (5) the oxygen-evolving rate of PS II was elevated by 51.89%. Taken together, the studies of the experiments showed that nano-anatase TiO(2) had bound to D1/D2/Cyt b559 complex, promoted the spectral responses, leading to the improvement of primary electron separation, electron transfer and light energy conversion of D1/D2/Cyt b559 complex.

  16. Promotion of nano-anatase TiO 2 on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach

    NASA Astrophysics Data System (ADS)

    Su, Mingyu; Liu, Huiting; Liu, Chao; Qu, Chunxiang; Zheng, Lei; Hong, Fashui

    2009-06-01

    Previous researches approved that photocatalysis activity of nano-TiO 2 could obviously increase photosynthetic effects of spinach, but the mechanism of improving light energy transfer and conversion is still unclear. In the present we investigated effects of nano-anatase TiO 2 on the spectral responses and photochemical activities of D1/D2/Cyt b559 complex of spinach. Several effects of nano-anatase TiO 2 were observed: (1) UV-vis spectrum was blue shifted in both Soret and Q bands, and the absorption intensity was obviously increased; (2) resonance Raman spectrum showed four main peaks, which are ascribed to carotene, and the Raman peak intensity was as 6.98 times as that of the control; (3) the fluorescence emission peak was blue shifted and the intensity was decreased by 23.59%; (4) the DCPIP photoreduction activity showed 129.24% enhancement; (5) the oxygen-evolving rate of PS II was elevated by 51.89%. Taken together, the studies of the experiments showed that nano-anatase TiO 2 had bound to D1/D2/Cyt b559 complex, promoted the spectral responses, leading to the improvement of primary electron separation, electron transfer and light energy conversion of D1/D2/Cyt b559 complex.

  17. 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.

  18. Chemical kinetics and photochemical data for use in stratospheric modeling

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Sander, S. P.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.; Kolb, C. E.; Molina, M. J.

    1992-01-01

    As part of a series of evaluated sets, rate constants and photochemical cross sections compiled by the NASA Panel for Data Evaluation are provided. The primary application of the data is in the modeling of stratospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena. Copies of this evaluation are available from the Jet Propulsion Laboratory.

  19. Chemical kinetic and photochemical data for use in stratospheric modelling

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Stief, L. J.; Kaufman, F.; Golden, D. M.; Hampton, R. F.; Kurylo, M. J.; Margitan, J. J.; Molina, M. J.; Watson, R. T.

    1979-01-01

    An evaluated set of rate constants and photochemical cross sections were compiled for use in modelling stratospheric processes. The data are primarily relevant to the ozone layer, and its possible perturbation by anthropogenic activities. The evaluation is current to, approximately, January, 1979.

  20. Nonlocal order parameters for the 1D Hubbard model.

    PubMed

    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.

  1. 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.

  2. 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.

  3. Computer Modelling of Photochemical Smog Formation

    ERIC Educational Resources Information Center

    Huebert, Barry J.

    1974-01-01

    Discusses a computer program that has been used in environmental chemistry courses as an example of modelling as a vehicle for teaching chemical dynamics, and as a demonstration of some of the factors which affect the production of smog. (Author/GS)

  4. 1-D blood flow modelling in a running human body.

    PubMed

    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.

  5. Photochemical reactions of various model protocell systems

    NASA Technical Reports Server (NTRS)

    Folsome, C. E.

    1986-01-01

    Models for the emergence of cellular life on the primitive Earth, and for physical environments of that era have been studied that embody these assumptions: (1) pregenetic cellular forms were phase-bounded systems primarily photosynthetic in nature, and (2) the early Earth environment was anoxic (lacking appreciable amounts of free hydrogen). It was found that organic structures can also be formed under anoxic conditions (N2, CO3=, H2O) by protracted longwavelength UV radiation. Apparently these structures form initially as organic layers upon CaCO3 crystalloids. The question remains as to whether the UV photosynthetic ability of such phase bounded structures is a curiosity, or a general property of phase bounded systems which is of direct interest to the emergence of cellular life. The question of the requirement and sailient features of a phase boundary for UV photosynthetic abilities was addressed by searching for similar general physical properties which might be manifest in a variety of other simple protocell-like structures. Since it has been shown that laboratory protocell models can effect the UV photosynthesis of low molecular weight compounds, this reaction is being used as an assay to survey other types of structures for similar UV photosynthetic reactions. Various kinds of structures surveyed are: (1) proteinoids; (2) liposomes; (3) reconstituted cell membrane spheroids; (4) coacervates; and (5) model protocells formed under anoxic conditions.

  6. 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.

  7. Photochemical trajectory modelling studies of the 1987 Antarctic spring vortex

    NASA Technical Reports Server (NTRS)

    Austin, J.; Jones, R. L.; Mckenna, D. S.

    1988-01-01

    Simulations of Antarctic ozone photochemistry performed using a photochemical model integrated along air parcel trajectories are described. This type of model has a major advantage at high latitudes of being able to simulate correctly the complex interaction between photolysis and temperature fields, which, because of the polar night cannot be represented accurately in a zonally averaged framework. Isentropic air parcel trajectories were computed using Meteorological Office global model analyses and forecast fields from positions along the ER-2 flight paths during the Airborne Antarctic Ozone Experiment in Austral Spring 1987. A photochemical model is integrated along these trajectories using the aircraft observations to initialize constituent concentrations. The model includes additional reactions of the ClO dimer and also bromine reactions, which are thought to play a significant role in Antarctica. The model also includes heterogeneous reactions which are invoked when the air parcel passes through a polar stratospheric cloud (PSC). The existence of a PSC is determined throughout the course of the model integration from the parcel temperature and the saturated vapour pressure of water over an assumed H2O/HNO3 mixture. The air parcel temperature is used to determine the saturated vapor pressure of HNO3 over the same mixture. Mixing ratios which exceed saturation result in condensation of the excess in the model and hence lead to a reduction of the amount of gas phase NO2 available for chemical reaction.

  8. 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.

  9. Examination of 1D Solar Cell Model Limitations Using 3D SPICE Modeling: Preprint

    SciTech Connect

    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.

  10. Lanczos diagonalizations of the 1-D Peierls-Hubbard model

    SciTech Connect

    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.

  11. 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.

  12. Statistical analysis of a global photochemical model of the atmosphere

    NASA Astrophysics Data System (ADS)

    Frol'Kis, V. A.; Karol', I. L.; Kiselev, A. A.; Ozolin, Yu. E.; Zubov, V. A.

    2007-08-01

    This is a study of the sensitivity of model results (atmospheric content of main gas constituents and radiative characteristics of the atmosphere) to errors in emissions of a number of atmospheric gaseous pollutants. Groups of the model variables most dependent on these errors are selected. Two variants of emissions are considered: one without their evolution and the other with their variation according to the IPCC scenario. The estimates are made on the basis of standard statistical methods for the results obtained with the detailed onedimensional radiative—photochemical model of the Main Geophysical Observatory (MGO). Some approaches to such estimations with models of higher complexity and to the solution of the inverse problem (i.e., the estimation of the necessary accuracy of external model parameters for obtaining the given accuracy of model results) are outlined.

  13. 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.

  14. Global emissions and models of photochemically active compounds

    SciTech Connect

    Penner, J.E.; Atherton, C.S.; Graedel, T.E.

    1993-05-20

    Anthropogenic emissions from industrial activity, fossil fuel combustion, and biomass burning are now known to be large enough (relative to natural sources) to perturb the chemistry of vast regions of the troposphere. A goal of the IGAC Global Emissions Inventory Activity (GEIA) is to provide authoritative and reliable emissions inventories on a 1{degree} {times} 1{degree} grid. When combined with atmospheric photochemical models, these high quality emissions inventories may be used to predict the concentrations of major photochemical products. Comparison of model results with measurements of pertinent species allows us to understand whether there are major shortcomings in our understanding of tropospheric photochemistry, the budgets and transport of trace species, and their effects in the atmosphere. Through this activity, we are building the capability to make confident predictions of the future consequences of anthropogenic emissions. This paper compares IGAC recommended emissions inventories for reactive nitrogen and sulfur dioxide to those that have been in use previously. We also present results from the three-dimensional LLNL atmospheric chemistry model that show how emissions of anthropogenic nitrogen oxides might potentially affect tropospheric ozone and OH concentrations and how emissions of anthropogenic sulfur increase sulfate aerosol loadings.

  15. 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.

  16. On the in vivo photochemical rate parameters for PDT reactive oxygen species modeling

    NASA Astrophysics Data System (ADS)

    Kim, Michele M.; Ghogare, Ashwini A.; Greer, Alexander; Zhu, Timothy C.

    2017-03-01

    Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in vitro. Recent developments allow for the estimation of some of these photochemical parameters in vivo. This review will cover the currently available in vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT.

  17. Photochemical-dynamical models of externally FUV irradiated protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Haworth, Thomas J.; Boubert, Douglas; Facchini, Stefano; Bisbas, Thomas G.; Clarke, Cathie J.

    2016-12-01

    There is growing theoretical and observational evidence that protoplanetary disc evolution may be significantly affected by the canonical levels of far-ultraviolet (FUV) radiation found in a star-forming environment, leading to substantial stripping of material from the disc outer edge even in the absence of nearby massive stars. In this paper, we perform the first full radiation hydrodynamic simulations of the flow from the outer rim of protoplanetary discs externally irradiated by such intermediate strength FUV fields, including direct modelling of the photon-dominated region which is required to accurately compute the thermal properties. We find excellent agreement between our models and the semi-analytic models of Facchini et al. (2016) for the profile of the flow itself, as well as the mass-loss rate and location of their `critical radius'. This both validates their results (which differed significantly from prior semi-analytic estimates) and our new numerical method, the latter of which can now be applied to elements of the problem that the semi-analytic approaches are incapable of modelling. We also obtain the composition of the flow, but given the simple geometry of our models we can only hint at some diagnostics for future observations of externally irradiated discs at this stage. We also discuss the potential for these models as benchmarks for future photochemical-dynamical codes.

  18. Transport and photochemical modeling. Studies of atmospheric species

    NASA Technical Reports Server (NTRS)

    Natarajan, M.

    1987-01-01

    A program of research studies related to the photochemistry, radiative transfer, and dynamics of the stratosphere is described. Investigations were conducted in two broad areas: (1) studies of the stratospheric processes and their response to external perturbations, and (2) analysis of satellite measurements in conjunction with theoretical models. Contemporary one dimensional photochemical, radiative-convective model was used to assess the impact of perturbations such as solar flux variability, increases in atmospheric carbon dioxide, chlorofluoromethanes and other greenhouse gases. Data from satellite experiments such as LIMS and SBUV, were used along with theoretical models to develop a climatology of trace species in the stratosphere. The consistency of contemporary ozone photochemistry was examined in the light of LIMS data. Research work also includes analysis of stratospheric nitrogen dioxide distributions from different satellite experiments, investigation of the wintertime latitudinal gradients in NO2, estimation of the stratospheric odd nitrogen level and its variability, and studies related to the changes in ozone in the Antarctic, and mid latitude Southern Hemisphere.

  19. APPLICATION OF BAYESIAN MONTE CARLO ANALYSIS TO A LAGRANGIAN PHOTOCHEMICAL AIR QUALITY MODEL. (R824792)

    EPA Science Inventory

    Uncertainties in ozone concentrations predicted with a Lagrangian photochemical air quality model have been estimated using Bayesian Monte Carlo (BMC) analysis. Bayesian Monte Carlo analysis provides a means of combining subjective "prior" uncertainty estimates developed ...

  20. Chemical kinetics and photochemical data for use in stratospheric modeling: Evaluation number 5

    NASA Technical Reports Server (NTRS)

    Demore, W. B.

    1982-01-01

    Sets of rate constants and photochemical cross sections compiled which were evaluated. The primary application of the data is in the modeling of stratospheric processes on the ozone layer and its possible perturbation by anthropogenic and natural phenomena are emphasized.

  1. Chemical kinetics and photochemical data for use in stratospheric modeling. Evaluation number 6

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Molina, M. J.; Watson, R. T.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.

    1983-01-01

    Evaluated sets of rate constants and photochemical cross sections are presented. The primary application of the data is in the modeling of stratospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena.

  2. 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.

  3. 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.

  4. Validation of 1-D transport and sawtooth models for ITER

    SciTech Connect

    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.

  5. 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.

  6. 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).

  7. 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

  8. 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.

  9. Potent neutralizing anti-CD1d antibody reduces lung cytokine release in primate asthma model

    PubMed Central

    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

  10. Potent neutralizing anti-CD1d antibody reduces lung cytokine release in primate asthma model.

    PubMed

    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.

  11. Kernel Density Reconstruction for Lagrangian Photochemical Modelling. Part 1: Model Formulation and Preliminary Tests

    SciTech Connect

    Monforti, F; Vitali, L; Bellasio, R; Bianconi, R

    2006-02-21

    In this paper a new approach to photochemical modeling is investigated and a lagrangian particle model named Photochemical Lagrangian Particle Model (PLPM) is described. Lagrangian particle models are a consolidated tool to deal with the dispersion of pollutants in the atmosphere. Good results have been obtained dealing with inert pollutants. In recent years, a number of pioneering works have shown as Lagrangian models can be of great interest when dealing with photochemistry, provided that special care is given in the reconstruction of chemicals concentration in the atmosphere. Density reconstruction can be performed through the so called ''box counting'' method: an Eulerian grid for chemistry is introduced and density is computed counting particles in each box. In this way one of the main advantages of the Lagrangian approach, the grid independence, is lost. Photochemical reactions are treated in PLPM by means of the complex chemical mechanism SAPRC90 and four density reconstruction methods have been developed, based on the kernel density estimator approach, in order to obtain grid-free accurate concentrations. These methods are all fully grid-free but they differ each other in considering local or global features of the particles distribution, in treating the Cartesian directions separately or together and in being based on receptors or particles positions in space.

  12. Utilization of UARS Data in Validation of Photochemical and Dynamical Mechanisms in Stratospheric Models

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Rodriquez, Jose M.; Hu, Wenjie; Danilin, Michael Y.; Shia, Run-Li

    1998-01-01

    The proposed work utilized Upper Atmosphere Research Satellite (UARS) measurements of short-lived and long-lived species, in conjunction with existing photochemical "box" models, trajectory models, and two-dimensional global models, to elucidate outstanding questions in our understanding of photochemical and dynamical mechanisms in the stratosphere. Particular emphasis was given to arriving at the best possible understanding of the chemical and dynamical contribution to the stratospheric ozone budget. Such understanding will increase confidence in the simulations carried out by assessment models.

  13. Utilization of UARS Data in Validation of Photochemical and Dynamical Mechanisms in Stratospheric Models

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Rodriquez, J. M.; Hu, W.; Danilin, M. Y.; Shia, R.-L.

    1998-01-01

    The proposed work utilized Upper Atmosphere Research Satellite (UARS) measurements of short-lived and long-lived species, in conjunction with existing photochemical "box" models, trajectory models, and two-dimensional global models, to elucidate outstanding questions in our understanding of photochemical and dynamical mechanisms in the stratosphere. Particular emphasis was given to arriving at the best possible understanding of the chemical and dynamical contributions to the stratospheric ozone budget. Such understanding will increase confidence in the simulations carried out by assessment models.

  14. Zebrafish model of photochemical thrombosis for translational research and thrombolytic screening in vivo.

    PubMed

    Lee, I-Ju; Yang, Yi-Cyun; Hsu, Jia-Wen; Chang, Wei-Tien; Chuang, Yung-Jen; Liau, Ian

    2017-04-01

    Acute thromboembolic diseases remain the major global cause of death or disability. Although an array of thrombolytic and antithrombotic drugs has been approved to treat or prevent thromboembolic diseases, many more drugs that target specific clotting mechanisms are under development. Here a novel zebrafish model of photochemical thrombosis is reported and its prospective application for the screening and preclinical testing of thrombolytic agents in vivo is demonstrated. Through photochemical excitation, a thrombus was induced to form at a selected section of the dorsal aorta of larval zebrafish, which had been injected with photosensitizers. Such photochemical thrombosis can be consistently controlled to occlude partially or completely the targeted blood vessel. Detailed mechanistic tests indicate that the zebrafish model of photochemical thrombosis exhibits essential features of classical coagulation and a thrombolytic pathway. For demonstration, tissue plasminogen activator (tPA), a clinically feasible thrombolytic agent, was shown to effectively dissolve photochemically induced blood clots. In light of the numerous unique advantages of zebrafish as a model organism, our approach is expected to benefit not only the development of novel thrombolytic and antithrombotic strategies but also the fundamental or translational research targeting hereditary thrombotic or coagulation disorders.

  15. Comparison of measured ozone in southeastern Virginia with computer predictions from a photochemical model

    NASA Technical Reports Server (NTRS)

    Wakelyn, N. T.; Gregory, G. L.

    1980-01-01

    Data for one day of the 1977 southeastern Virginia urban plume study are compared with computer predictions from a traveling air parcel model using a contemporary photochemical mechanism with a minimal description of nonmethane hydrocarbon (NMHC) constitution and chemistry. With measured initial NOx and O3 concentrations and a current separate estimate of urban source loading input to the model, and for a variation of initial NMHC over a reasonable range, an ozone increase over the day is predicted from the photochemical simulation which is consistent with the flight path averaged airborne data.

  16. A Framework for Evaluating Regional-Scale Numerical Photochemical Modeling Systems

    EPA Science Inventory

    This paper discusses the need for critically evaluating regional-scale (~ 200-2000 km) three dimensional numerical photochemical air quality modeling systems to establish a model's credibility in simulating the spatio-temporal features embedded in the observations. Because of li...

  17. Benchmarks and models for 1-D radiation transport in stochastic participating media

    SciTech Connect

    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.

  18. 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.

  19. A Coupled Ion-Neutral Photochemical Model for the Titan Atmosphere

    NASA Astrophysics Data System (ADS)

    Vuitton, Veronique; Yelle, Roger V.; Klippenstein, Stephen J.; Hörst, Sarah M.; Lavvas, Panayotis

    2014-11-01

    Recent observations from the Cassini-Huygens spacecraft and the Herschel space observatory drastically increased our knowledge of Titan's chemical composition. The combination of data retrieved by Cassini INMS, UVIS, and CIRS allows deriving the vertical profiles of half a dozen species from 1000 to 100 km, while the HIFI instrument on Herschel reported on the first identification of HNC. Partial data or upper limits are available for almost 20 other CHON neutral species. The INMS and CAPS instruments onboard Cassini also revealed the existence of numerous positive and negative ions in Titan's upper atmosphere. We present the results of a 1D coupled ion-neutral photochemical model intended for the interpretation of the distribution of gaseous species in the Titan atmosphere. The model extends from the surface to the exobase. The atmospheric background, boundary conditions, vertical transport and aerosol opacity are all constrained by the Cassini-Huygens observations. The chemical network includes reactions between hydrocarbons, nitrogen and oxygen bearing species (including some species containing both nitrogen and oxygen, such as NO). It takes into account neutrals and both positive and negative ions with m/z extending up to about 100 u. Ab initio Transition State Theory calculations are performed in order to evaluate the rate coefficients and products for critical reactions. The calculated vertical profiles of neutral and ion species generally agree with the existing observational data; some differences are highlighted. We discuss the chemical and physical processes responsible for the production and loss of some key species. We find that the production of neutral species in the upper atmosphere from electron-ion recombination reactions and neutral-neutral radiative association reactions is significant. In the stratosphere, the vertical profile of (cyano)polyynes is extremely sensitive to their heterogeneous loss on aerosols, a process that remains to be

  20. Compilation and interpretation of photochemical model performance statistics published between 2006 and 2012

    NASA Astrophysics Data System (ADS)

    Simon, Heather; Baker, Kirk R.; Phillips, Sharon

    2012-12-01

    Regulatory and scientific applications of photochemical models are typically evaluated by comparing model estimates to measured values. It is important to compare quantitative model performance metrics to a benchmark or other studies to provide confidence in the modeling results. Since strict model performance guidelines may not be appropriate for many applications, model evaluations presented in recent literature have been compiled to provide a general assessment of model performance over a broad range of modeling systems, modeling periods, intended use, and spatial scales. Operational model performance is compiled for ozone, total PM2.5, speciated PM2.5, and wet deposition of sulfate, nitrate, ammonium, and mercury. The common features of the model performance compiled from literature are photochemical models that have been applied over the United States or Canada and use modeling platforms intended to generally support research, regulatory or forecasting applications. A total of 69 peer-reviewed articles which include operational model evaluations and were published between 2006 and March 2012 are compiled to summarize typical model performance. The range of reported performance is presented in graphical and tabular form to provide context for operational performance evaluation of future photochemical model applications. In addition, recommendations are provided regarding which performance metrics are most useful for comparing model applications and the best approaches to match model estimates and observations in time and space for the purposes of metric aggregations.

  1. Has the Performance of Regional-Scale Photochemical Modelling Systems Changed over the Past Decade?

    EPA Science Inventory

    This study analyzed summertime ozone concentrations that have been simulated by various regional-scale photochemical modelling systems over the Eastern U.S. as part of more than ten independent studies. Results indicate that there has been a reduction of root mean square errors ...

  2. Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling. Evaluation No. 12

    NASA Technical Reports Server (NTRS)

    DeMore, W. B.; Sander, S. P.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.; Kolb, C. E.; Molina, M. J.

    1997-01-01

    This is the twelfth in a series of evaluated sets of rate constants and photochemical cross sections compiled by the NASA Panel for Data Evaluation. The primary application of the data is in the modeling of stratospheric processes, with special emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena.

  3. Diagnostic Evaluation of Ozone Production and Horizontal Transport in a Regional Photochemical Air Quality Modeling System

    EPA Science Inventory

    A diagnostic model evaluation effort has been performed to focus on photochemical ozone formation and the horizontal transport process since they strongly impact the temporal evolution and spatial distribution of ozone (O3) within the lower troposphere. Results from th...

  4. Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes

    SciTech Connect

    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

  5. 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.

  6. Accuracy of 1D microvascular flow models in the limit of low Reynolds numbers.

    PubMed

    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.

  7. Interfacing the NRL 1-D High Vertical Resolution Aerosol Model with COAMPS

    DTIC Science & Technology

    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

  8. 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...

  9. Review of Zero-D and 1-D Models of Blood Flow in the Cardiovascular System

    PubMed Central

    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

  10. A coupled ion-neutral photochemical model for the Titan atmosphere

    NASA Astrophysics Data System (ADS)

    Vuitton, V.; Yelle, R. V.; Klippenstein, S. J.; Horst, S. M.; Lavvas, P.

    2013-12-01

    Recent observations from the Cassini-Huygens spacecraft and the Herschel space observatory drastically increased our knowledge of Titan's chemical composition. The combination of data retrieved by Cassini INMS, UVIS, and CIRS allows deriving the vertical profiles of half a dozen species from 1000 to 100 km, while the HIFI instrument on Herschel reported on the first identification of HNC. Partial data or upper limits are available for almost 20 other CHON neutral species. The INMS and CAPS instruments onboard Cassini also revealed the existence of numerous positive and negative ions in Titan's upper atmosphere. We present the results of a 1D coupled ion-neutral photochemical model intended for the interpretation of the distribution of gaseous species in the Titan atmosphere. The model extends from the surface to the exobase. The atmospheric background, boundary conditions, vertical transport and aerosol opacity are all constrained by the Cassini-Huygens observations. The chemical network includes reactions between hydrocarbons, nitrogen and oxygen bearing species (including some species containing both nitrogen and oxygen, such as NO). It takes into account neutrals and both positive and negative ions with m/z extending up to about 100 u. Ab initio Transition State Theory calculations are performed in order to evaluate the rate coefficients and products for critical reactions. The production of minor nitrogen-bearing species and hydrocarbons is initiated by the dissociation and ionization of N2 and CH4 by solar VUV/EUV photons and associated photoelectrons in the upper atmosphere. We incorporate new high-resolution isotopic photoabsorption and photodissociation cross sections for N2 as well as new photodissociation branching ratios for CH4 and C2H2. The photodissociation of hydrocarbon radicals is taken into account and its impact on the chemistry is discussed for the first time. The presence of oxygen-bearing species is explained by an influx of oxygen originating

  11. 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.

  12. Photochemical model of photodynamic therapy applied to skin diseases by a topical photosensitizer

    NASA Astrophysics Data System (ADS)

    Fanjul-Vélez, F.; Salas-García, I.; Fernández-Fernández, L. A.; López-Escobar, M.; Buelta-Carrillo, L.; Ortega-Quijano, N.; Arce-Diego, J. L.

    2009-07-01

    Photodynamic Therapy (PDT) provides a non-invasive, efficient and safe treatment for skin diseases with good cosmetic results. These characteristics make this technique more advantageous than radiotherapy or chemotherapy, which present limitations in a big number of lesions, are painful in many cases and produce non-satisfactory cosmetic results. We present the clinical results obtained at present by this optical technique and a photochemical model of the PDT process applied to the skin by means of a topical photosensitizer, in order to find the optimal PDT parameters. Optical propagation inside the tissue is calculated by means of the three dimensional Beer-Lambert law, due to its facility to be integrated in the differential equations system used to model the photochemical processes involved. With this information it is possible to obtain an initial estimation about the optimal drug dose and the optical power required.

  13. Chemical kinetics and photochemical data for use in stratospheric modeling evaluation Number 8

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Molina, M. J.; Sander, S. P.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.

    1987-01-01

    This is the eighth in a series of evaluated sets of rate constants and photochemical cross sections compiled by the NASA Panel for Data Evaluation. The primary application of the data is in the modeling of stratospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena. Copies of this evaluation are available from the Jet Propulsion Laboratory, Documentation Section, 111-116B, California Institute of Technology, Pasadena, California, 91109.

  14. Thermodynamic nature of vitrification in a 1D model of a structural glass former

    SciTech Connect

    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.

  15. SILVA: EDF two-phase 1D annular model of a CFB boiler furnace

    SciTech Connect

    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.

  16. 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.

  17. Thermodynamic nature of vitrification in a 1D model of a structural glass former.

    PubMed

    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.

  18. 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.

  19. 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.

  20. A Systematic Comparison between 1-D and 3-D Hemodynamics in Compliant Arterial Models

    PubMed Central

    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

  1. 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.

  2. Verification and comparison of four numerical schemes for a 1D viscoelastic blood flow model.

    PubMed

    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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Lagrangian photochemical modeling studies of the 1987 Antarctic spring vortex. I - Comparison with AAOE observations

    NASA Technical Reports Server (NTRS)

    Jones, R. L.; Austin, J.; Mckenna, D. S.; Anderson, J. G.; Fahey, D. W.; Farmer, C. B.; Vedder, J. F.

    1989-01-01

    Results from the Lagrangian photochemical model integrated along computed air parcel trajectories intersected by the ER-2 aircraft are presented and compared with AAOE observations. According to the model, the BrO observations made from the ER-2 within the dehydrated denitrified region are consistent with there being approximately 5 parts per trillion by volume of BrO(y) at 428 K in spring. Within the high ClO region, ozone destruction rates are expected to exceed 2 percent/d with approximately 80 percent due to the ClO dimer mechanism.

  8. 1D-3D hybrid modeling-from multi-compartment models to full resolution models in space and time.

    PubMed

    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

  9. Quantum Nucleation of Phase Slips in a 1D Model of a Superfluid

    SciTech Connect

    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}

  10. 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.

  11. 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.

  12. Survey of Multi-Material Closure Models in 1D Lagrangian Hydrodynamics

    SciTech Connect

    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.

  13. Multiscale Modeling Techniques for Plasma: 1D Scaling Results and Application to Magnetic Reconnection

    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.

  14. Lagrangian photochemical modeling studies of the 1987 Antarctic spring vortex. II - Seasonal trends in ozone

    NASA Technical Reports Server (NTRS)

    Austin, J.; Jones, R. L.; Mckenna, D. S.; Buckland, A. T.; Anderson, J. G.; Fahey, D. W.; Farmer, C. B.; Heidt, L. E.; Proffitt, M. H.; Vedder, J. F.

    1989-01-01

    A photochemical model consisting of 40 species and 107 reactions is integrated along 80-day air parcel trajectories calculated in the lower stratosphere for the springtime Antarctic. For the trajectory starting at 58 deg S, which may be regarded as outside the circumpolar vortex, only a small change in O3 occurs in the model. In contrast, for the air parcel starting in the vortex at 74 deg S, the O3 concentration is reduced by 93 percent during the 80 days from the beginning of August to late October. The model results for several species are compared with measurements from the Airborne Antarctic Ozone Experiment and, in general, good agreement is obtained. In the model, the dentrification of the air parcels in polar stratospheric clouds increases the amount of chlorine present in active form. Heterogeneous reactions maintain high active chlorine which destroys O3 via the formation of the ClO dimer. Results of calculations with reduced concentrations of inorganic chlorine show considerably reduced O3 destruction rates and compare favorably with the behavior of total O3 since the late 1970s. The remaining major uncertainties in the photochemical aspects of the Antarctic ozone hole are highlighted.

  15. Comparison of parameterized nitric acid rainout rates using a coupled stochastic-photochemical tropospheric model

    NASA Technical Reports Server (NTRS)

    Stewart, Richard W.; Thompson, Anne M.; Owens, Melody A.; Herwehe, Jerold A.

    1989-01-01

    A major tropospheric loss of soluble species such as nitric acid results from scavenging by water droplets. Several theoretical formulations have been advanced which relate an effective time-independent loss rate for soluble species to statistical properties of precipitation such as the wet fraction and length of a precipitation cycle. In this paper, various 'effective' loss rates that have been proposed are compared with the results of detailed time-dependent model calculations carried out over a seasonal time scale. The model is a stochastic precipitation model coupled to a tropospheric photochemical model. The results of numerous time-dependent seasonal model runs are used to derive numerical values for the nitric acid residence time for several assumed sets of preciptation statistics. These values are then compared with the results obtained by utilizing theoretical 'effective' loss rates in time-independent models.

  16. 2D-photochemical modeling of Saturn’s stratosphere: hydrocarbon and water distributions

    NASA Astrophysics Data System (ADS)

    Hue, Vincent; Cavalié, Thibault; Hersant, Franck; Dobrijevic, Michel; Greathouse, Thomas; Lellouch, Emmanuel; Hartogh, Paul; Cassidy, Timothy; Spiga, Aymeric; Guerlet, Sandrine; Sylvestre, Melody

    2014-11-01

    Saturn’s axial tilt of 27° produces seasons in a similar way as on Earth. The seasonal forcing over Saturn’s 30 years period influences the production/loss of the major atmospheric absorbers and coolants through photochemistry, and influences therefore Saturn’s stratospheric temperatures. We have developed a 2D time-dependent photochemical model of Saturn’s atmosphere [Hue et al., in prep.], coupled to a radiative-climate model [Greathouse et al., 2008] to study seasonal effects on its atmospheric composition. Cassini spacecraft has revealed that the distribution of hydrocarbons in Saturn’s stratosphere [Guerlet et al., 2009] differs from pure photochemical predictions, i.e. without meridional transport [Moses et al., 2005]. Differences between the observed distribution of hydrocarbons and 2D-photochemical predictions are likely to be an indicator of dynamical forcing.Disentangling the origin of water in the stratosphere of this planet has been a long-term issue. Due to Saturn’s cold tropopause trap, which acts as a transport barrier, the water vapor observed by the Infrared Space Observatory (ISO) [Feuchtgruber et al., 1997] has an external origin. Three external sources have been identified: (i) permanent flux from interplanetary dust particles, (ii) local sources form planetary environments (rings, satellites), (iii) large cometary impacts, similar to Shoemaker-Levy 9 on Jupiter. Previous observations of Saturn with Herschel’s Hsso program [Hartogh et al., 2009] led to the detection of a water torus around Saturn [Hartogh et al., 2011], fed by Enceladus’ geysers. A substantial fraction of this torus is predicted to be a local source of water for Saturn’s and its satellites, as it will spread in this system [Cassidy et al., 2010]. Using the new 2D-photochemical model, we test here the validity of Enceladus’ torus as the source of Saturn’s stratospheric water.References : Hue et al., in prep. Greathouse et al., 2008. AGU Fall Meeting

  17. 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.

  18. EFDC1D - A ONE DIMENSIONAL HYDRODYNAMIC AND SEDIMENT TRANSPORT MODEL FOR RIVER AND STREAM NETWORKS: MODEL THEORY AND USERS GUIDE

    EPA Science Inventory

    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...

  19. 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.

  20. GE SBWR stability analysis using TRAC-BF1 1-D kinetics model

    SciTech Connect

    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.

  1. Fluid friction and wall viscosity of the 1D blood flow model.

    PubMed

    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.

  2. 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.

  3. 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.

  4. Nanoelectronic Modeling (NEMO): Moving from commercial grade 1-D simulation to prototype 3-D simulation

    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

  5. 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.

  6. Action spectrum for photochemical retinal pigment epithelium (RPE) disruption in an in vivo monkey model

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Sabarinathan, Ranjani; Bubel, Tracy; Williams, David R.; Hunter, Jennifer J.

    2016-03-01

    Observations of RPE disruption and autofluorescence (AF) photobleaching at light levels below the ANSI photochemical maximum permissible exposure (MPE) (Morgan et al., 2008) indicates a demand to modify future light safety standards to protect the retina from harm. To establish safe light exposures, we measured the visible light action spectrum for RPE disruption in an in vivo monkey model with fluorescence adaptive optics retinal imaging. Using this high resolution imaging modality can provide insight into the consequences of light on a cellular level and allow for longitudinal monitoring of retinal changes. The threshold retinal radiant exposures (RRE) for RPE disruption were determined for 4 wavelengths (460, 488, 544, and 594 nm). The anaesthetized macaque retina was exposed to a uniform 0.5° × 0.5° field of view (FOV). Imaging within a 2° × 2° FOV was performed before, immediately after and at 2 week intervals for 10 weeks. At each wavelength, multiple RREs were tested with 4 repetitions each to determine the threshold for RPE disruption. For qualitative analysis, RPE disruption is defined as any detectable change from the pre exposure condition in the cell mosaic in the exposed region relative to the corresponding mosaic in the immediately surrounding area. We have tested several metrics to evaluate the RPE images obtained before and after exposure. The measured action spectrum for photochemical RPE disruption has a shallower slope than the current ANSI photochemical MPE for the same conditions and suggests that longer wavelength light is more hazardous than other measurements would suggest.

  7. Adaptation of a 2-D Photochemical Model to Improve Our Understanding of Saturn's Atmosphere

    NASA Astrophysics Data System (ADS)

    Edgington, Scott G.; Simon-Miller, A. A.; Achterberg, R.; Bjoraker, G.; Romani, P.; Flasar, F. M.; Colwell, J.

    2006-09-01

    We report progress in adapting a two dimensional photochemical model to Saturn. Previously, this model was applied to Jupiter (Edgington, et al., 2001) to track tracers such as ammonia in the Jovian troposphere. The chemistry portion of this model has the ability to model ammonia, phosphine, and hydrocarbon photochemical families (Edgington, et al., 1999). The transport portion is based on the transport model used to model the evolution of materials deposited by Comet Shoemaker-Levy 9 (Friedson, et al., 1999). The model is used to look at the variation of several molecules in Saturn's atmosphere accounting for the filtering of ultraviolet photons by Saturn's rings as measured by Cassini/UVIS and the thermal structure observed by Cassini/CIRS. We compare results from this model to the abundances of several molecules, e.g. propane (Simon-Miller, et al., 2005) and phosphine, derived from Cassini/CIRS, HST/FOS, and ISO data sets. Composition differences between the northern ring-shadowed atmophere and the nominal sunlit atmosphere will be examined. More research into Saturn's zonal averaged meridional circulation is needed. Edgington, S.G., et al., 1999. Ammonia and eddy mixing variations in the southern hemisphere of Jupiter from HST Faint Object Spectrograph Observations. Icarus, 142, 342-357. Edgington, S.G., West, R.A., Friedson, A.J., and Atreya, S.K., 2001. A 2-D photochemical model with meridional circulation and microphysics. Jupiter: Planet, Satellites, and Magnetosphere - Boulder, CO, June 25-30. Friedson, A.J.; West, R.A.; Hronek, A.K.; Larsen, N.A.; and Dalal, N., 1999. Transport and Mixing in Jupiter's Stratosphere Inferred from Comet S-L9 Dust Migration. Icarus, 138, 141-156. Simon-Miller, A.A., et al., 2005. Cassini CIRS Measurements of Benzene, Propane and Carbon Dioxide on Saturn. B.A.A.S. 37, 682. The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the

  8. 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

  9. Quantum Yields and Rate Constants of Photochemical and Nonphotochemical Excitation Quenching (Experiment and Model).

    PubMed Central

    Laisk, A.; Oja, V.; Rasulov, B.; Eichelmann, H.; Sumberg, A.

    1997-01-01

    Sunflower (Helianthus annuus L.), cotton (Gossypium hirsutum L.), tobacco (Nicotiana tabacum L.), sorghum (Sorghum bicolor Moench.), amaranth (Amaranthus cruentus L.), and cytochrome b6f complex-deficient transgenic tobacco leaves were used to test the response of plants exposed to differnt light intensities and CO2 concentrations before and after photoinhibition at 4000 [mu]mol photons m-2 s-1 and to thermoinhibition up to 45[deg]C. Quantum yields of photochemical and nonphotochemical excitation quenching (YP and YN) and the corresponding relative rate constants for excitation capture from the antenna-primary radical pair equilibrium system (k[prime]P and k[prime]N) were calculated from measured fluorescence parameters. The above treatments resulted in decreases in YP and K[prime]P and in approximately complementary increases in YN and K[prime]N under normal and inhibitory conditions. The results were reproduced by a mathematical model of electron/proton transport and O2 evolution/CO2 assimilation in photosynthesis based on budget equations for the intermediates of photosynthesis. Quantitative differences between model predictions and experiments are explainable, assuming that electron transport is organized into domains that contain relatively complete electron and proton transport chains (e.g. thylakoids). With the complementation that occurs between the photochemical and nonphotochemical excitation quenching, the regulatory system can constantly maintain the shortest lifetime of excitation necessary to avoid the formation of chlorophyll triplet states and singlet oxygen. PMID:12223845

  10. 1D numerical model of muddy subaqueous and subaerial debris flows

    USGS Publications Warehouse

    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.

  11. A simple framework for modelling the photochemical response to solar spectral irradiance variability in the stratosphere

    NASA Astrophysics Data System (ADS)

    Muncaster, R.; Bourqui, M. S.; Chabrillat, S.; Viscardy, S.; Melo, S. M. L.; Charbonneau, P.

    2012-08-01

    The stratosphere is thought to play a central role in the atmospheric response to solar irradiance variability. Recent observations suggest that the spectral solar irradiance (SSI) variability involves significant time-dependent spectral variations, with variable degrees of correlation between wavelengths, and new reconstructions are being developed. In this paper, we propose a simplified modelling framework to characterise the effect of short term SSI variability on stratospheric ozone. We focus on the pure photochemical effect, for it is the best constrained one. The photochemical effect is characterised using an ensemble simulation approach with multiple linear regression analysis. A photochemical column model is used with interactive photolysis for this purpose. Regression models and their coefficients provide a characterisation of the stratospheric ozone response to SSI variability and will allow future inter-comparisons between different SSI reconstructions. As a first step in this study, and to allow comparison with past studies, we take the representation of SSI variability from the Lean (1997) solar minimum and maximum spectra. First, solar maximum-minimum response is analysed for all chemical families and partitioning ratios, and is compared with past studies. The ozone response peaks at 0.18 ppmv (approximately 3%) at 37 km altitude. Second, ensemble simulations are regressed following two linear models. In the simplest case, an adjusted coefficient of determination R2 larger than 0.97 is found throughout the stratosphere using two predictors, namely the previous day's ozone perturbation and the current day's solar irradiance perturbation. A better accuracy (R2 larger than 0.9992) is achieved with an additional predictor, the previous day's solar irradiance perturbation. The regression models also provide simple parameterisations of the ozone

  12. 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

  13. 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.

  14. Method of single expression: an exact solution for wavelength scale 1D photonic structure computer modeling

    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.

  15. Multiscale Modeling Techniques for Plasmas: 1D Scaling Results and Application to Magnetic Reconnection

    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.

  16. 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.

  17. 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.

  18. A FRAMEWORK FOR EVALUATING REGIONAL-SCALE NUMERICAL PHOTOCHEMICAL MODELING SYSTEMS

    PubMed Central

    Dennis, Robin; Fox, Tyler; Fuentes, Montse; Gilliland, Alice; Hanna, Steven; Hogrefe, Christian; Irwin, John; Rao, S.Trivikrama.; Scheffe, Richard; Schere, Kenneth; Steyn, Douw; Venkatram, Akula

    2011-01-01

    This paper discusses the need for critically evaluating regional-scale (~200-2000 km) three-dimensional numerical photochemical air quality modeling systems to establish a model’s credibility in simulating the spatio-temporal features embedded in the observations. Because of limitations of currently used approaches for evaluating regional air quality models, a framework for model evaluation is introduced here for determining the suitability of a modeling system for a given application, distinguishing the performance between different models through confidence-testing of model results, guiding model development, and analyzing the impacts of regulatory policy options. The framework identifies operational, diagnostic, dynamic, and probabilistic types of model evaluation. Operational evaluation techniques include statistical and graphical analyses aimed at determining whether model estimates are in agreement with the observations in an overall sense. Diagnostic evaluation focuses on process-oriented analyses to determine whether the individual processes and components of the model system are working correctly, both independently and in combination. Dynamic evaluation assesses the ability of the air quality model to simulate changes in air quality stemming from changes in source emissions and/or meteorology, the principal forces that drive the air quality model. Probabilistic evaluation attempts to assess the confidence that can be placed in model predictions using techniques such as ensemble modeling and Bayesian model averaging. The advantages of these types of model evaluation approaches are discussed in this paper. PMID:21461126

  19. Establishing a conceptual model for photochemical ozone pollution in subtropical Hong Kong

    NASA Astrophysics Data System (ADS)

    Ling, Z. H.; Guo, H.; Zheng, J. Y.; Louie, P. K. K.; Cheng, H. R.; Jiang, F.; Cheung, K.; Wong, L. C.; Feng, X. Q.

    2013-09-01

    Photochemical ozone (O3) formation is related to its precursors and meteorological conditions. A conceptual model of O3 air pollution is developed based on the analysis of data obtained at Tung Chung (TC) in Hong Kong. By comparing meteorological parameters between O3 and non-O3 episode days, it was found that high temperatures, strong solar radiation, low wind speeds and relative humidity, northeasterly and/or northwesterly prevailing winds were favorable for the O3 formation, while tropical cyclones were most conducive to the occurrence of O3 episodes. Backward trajectories simulation and graphical illustration of O3 pollution suggested that super-regional (i.e. central and eastern China) and regional (i.e. Pearl River Delta, southern China) transport was another factor that contributed to high O3 levels in Hong Kong. The photochemical O3 formation, generally VOC-limited in Hong Kong, was controlled by a small number of volatile organic compounds (VOCs). Furthermore, the positive matrix factorization (PMF) simulation suggested that solvent usage and vehicular emissions are the major contributors to ambient VOCs in Hong Kong. Finally, this paper presents recommendations for further O3 research and implementation of O3 control strategies.

  20. On constitutive functions for hindered settling velocity in 1-D settler models: Selection of appropriate model structure.

    PubMed

    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.

  1. Testing the accuracy of a 1-D volcanic plume model in estimating mass eruption rate

    USGS Publications Warehouse

    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.

  2. ESTIMATION OF EMISSION ADJUSTMENTS FROM THE APPLICATION OF FOUR-DIMENSIONAL DATA ASSIMILATION TO PHOTOCHEMICAL AIR QUALITY MODELING. (R826372)

    EPA Science Inventory

    Four-dimensional data assimilation applied to photochemical air quality modeling is used to suggest adjustments to the emissions inventory of the Atlanta, Georgia metropolitan area. In this approach, a three-dimensional air quality model, coupled with direct sensitivity analys...

  3. 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

  4. 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.

  5. Significance of flow clustering and sequencing on sediment transport: 1D sediment transport modelling

    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

  6. 1D-3D hybrid modeling—from multi-compartment models to full resolution models in space and time

    PubMed Central

    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

  7. Modeling of simulated photochemical smog with kinetic mechanisms. Volume 1. Final report, July 1978-September 1979

    SciTech Connect

    Whitten, G.Z.; Killus, J.P.; Hogo, H.

    1980-02-01

    Mechanisms that describe the formation of photochemical smog are developed using a computer modeling technique directed toward the simulation of data collected in two smog chambers: an indoor chamber and a dual outdoor chamber. The results of simulating 164 different experiments are presented in Vol. 1. Individual compounds for which specific experiments were simulated and mechanisms developed include the following: formaldehyde, acetaldehyde, ethylene, propylene, butane, and toluene. Experiments in both chambers were simulated for all these compounds. The mechanisms reported describe the decay of the precursor organic compound, formation and decay of secondary organic compounds, conversion of nitrogen oxides, formation of nitrates, and the appearance and decay of ozone. Special emphasis is given to the chemistry of toluene. Also included is a study of a generalized smog-based or carbon-bond mechanism developed in a previous study.

  8. Benzophenone-based photochemical micropatterning of biomolecules to create model substrates and instructive biomaterials.

    PubMed

    Turgeon, Aurora J; Harley, Brendan A; Bailey, Ryan C

    2014-01-01

    The extracellular matrix (ECM) is a dynamic and heterogeneous environment that controls many aspects of cell behavior. Not surprisingly, many different approaches have focused on creating model substrates that recapitulate the biomolecular, topographical, and mechanical properties of the ECM for in vitro studies of cell behavior. This chapter details a general, versatile method for the spatially controlled deposition of multiple biomolecules onto both planar and topographically complex support structures with micrometer resolution. This approach is based upon the well-understood photochemical UV crosslinking of benzophenone (BP) to solution-phase biomolecules. This is a molecularly general strategy that can be utilized to immobilize biomolecules onto any surface prefunctionalized with BP. Examples described herein include modification of planar and corrugated glass substrates as well as collagen-glycosaminoglycan biomaterials configured either as highly porous scaffolds or nonporous membranes with a variety of biomolecular targets, including proteins, glycoproteins, and carbohydrates.

  9. 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.

  10. A Model Study of the Photochemical Fate of As(III) in Paddy-Water.

    PubMed

    Carena, Luca; Vione, Davide

    2017-03-11

    The APEX (Aqueous Photochemistry of Environmentally-occurring Xenobiotics) software previously developed by one of us was used to model the photochemistry of As(III) in paddy-field water, allowing a comparison with biotic processes. The model included key paddy-water variables, such as the shielding effect of the rice canopy on incident sunlight and its monthly variations, water pH, and the photochemical parameters of the chromophoric dissolved organic matter (CDOM) occurring in paddy fields. The half-life times (t1/2) of As(III) photooxidation to As(V) would be ~20-30 days in May. In contrast, the photochemical oxidation of As(III) would be much slower in June and July due to rice-canopy shading of radiation because of plant growth, despite higher sunlight irradiance. At pH < 8 the photooxidation of As(III) would mainly be accounted for by reaction with transient species produced by irradiated CDOM (here represented by the excited triplet states ³CDOM(*), neglecting the possibly more important reactions with poorly known species such as the phenoxy radicals) and, to a lesser extent, with the hydroxyl radicals (HO(•)). However, the carbonate radicals (CO₃(•-)) could be key photooxidants at pH > 8.5 provided that the paddy-water ³CDOM(*) is sufficiently reactive toward the oxidation of CO₃(2-). In particular, if paddy-water ³CDOM(*) oxidizes the carbonate anion with a second-order reaction rate constant near (or higher than) 10⁶ M(-1)·s(-1), the photooxidation of As(III) could be quite fast at pH > 8.5. Such pH conditions can be produced by elevated photosynthetic activity that consumes dissolved CO₂.

  11. Atmospheric photochemical reactivity and ozone production at two sites in Hong Kong: Application of a Master Chemical Mechanism-photochemical box model

    NASA Astrophysics Data System (ADS)

    Ling, Z. H.; Guo, H.; Lam, S. H. M.; Saunders, S. M.; Wang, T.

    2014-09-01

    A photochemical box model incorporating the Master Chemical Mechanism (v3.2), constrained with a full suite of measurements, was developed to investigate the photochemical reactivity of volatile organic compounds at a semirural site (Mount Tai Mo Shan (TMS)) and an urban site (Tsuen Wan (TW)) in Hong Kong. The levels of ozone (O3) and its precursors, and the magnitudes of the reactivity of O3 precursors, revealed significant differences in the photochemistry at the two sites. Simulated peak hydroperoxyl radical (HO2) mixing ratios were similar at TW and TMS (p = 0.05), while the simulated hydroxyl radical (OH) mixing ratios were much higher at TW (p < 0.05), suggesting different cycling processes between OH and HO2 at the two sites. The higher OH at TW was due to high-NO mixing ratios, which shifted the HOx (OH + HO2) balance toward OH by the propagation of HO2 and alkyl peroxy radicals (RO2) with NO. HOx production was dominated by O3 photolysis at TMS, but at TW, both HCHO and O3 photolyses were found to be major contributors. By contrast, radical-radical reactions governed HOx radical losses at TMS, while at TW, the OH + NO2 reaction was found to dominate in the morning and the radical-radical reactions at noon. Overall, the conversion of NO to NO2 by HO2 dictated the O3 production at the two sites, while O3 destruction was dominated by the OH + NO2 reaction at TW, and at TMS, O3 photolysis and the O3 + HO2 reaction were the major mechanisms. The longer OH chain length at TMS indicated that more O3 was produced for each radical that was generated at this site.

  12. 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

  13. 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.

  14. Modelling Hydrology of a Single Bioretention System with HYDRUS-1D

    PubMed Central

    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

  15. Modelling hydrology of a single bioretention system with HYDRUS-1D.

    PubMed

    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.

  16. 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.

  17. 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

  18. 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.

  19. 1-D/3-D geologic model of the Western Canada Sedimentary Basin

    USGS Publications Warehouse

    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

  20. EVALUATING THE PERFORMANCE OF REGIONAL-SCALE PHOTOCHEMICAL MODELING SYSTEMS. PART III-PRECURSOR PREDICTIONS. (R825260)

    EPA Science Inventory

    Abstract

    Two regional-scale photochemical modeling systems, RAMS/UAM-V and MM5/MAQSIP, are used to simulate precursor concentrations for 4 June¯31 August 1995 period. The time series of simulated and observed precursor concentrations are spectrally deco...

  1. An influence of solar activity on latitudinal distribution of atmospheric ozone and temperature in 2-D radiative-photochemical model

    NASA Technical Reports Server (NTRS)

    Dyominov, I. G.

    1989-01-01

    On the basis of the 2-D radiative-photochemical model of the ozone layer at heights 0 to 60 km in the Northern Hemisphere there are revealed and analyzed in detail the characteristic features of the season-altitude-latitude variations of ozone and temperature due to changes of the solar flux during the 11 year cycle, electron and proton precipitations.

  2. Methods for reducing biases and errors in regional photochemical model outputs for use in emission reduction and exposure assessments

    EPA Science Inventory

    In the United States, regional-scale photochemical models are being used to design emission control strategies needed to meet the relevant National Ambient Air Quality Standards (NAAQS) within the framework of the attainment demonstration process. Previous studies have shown that...

  3. Chemical kinetic and photochemical data for use in stratospheric modeling evaluation number 4: NASA panel for data evaluation

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Evaluated sets of rate constants and photochemical cross sections compiled by the Panel are presented. The primary application of the data is in the modelling of stratospheric processes, with particular emphasis on the ozone layer and its possible perturbation by anthropogenic and natural phenomena.

  4. UPDATED PHOTOCHEMICAL MODELING FOR CALIFORNIA'S SOUTH COAST AIR BASIN: COMPARISON OF CHEMICAL MECHANISMS AND MOTOR VEHICLE EMISSION INVENTORIES. (R824792)

    EPA Science Inventory

    Large uncertainties remain in photochemical models used
    to relate emissions of VOC and NOx to ambient
    O3
    concentrations. Bias in motor vehicle emission
    estimates
    for VOC has been a long-standing concern. An improved
    Eul...

  5. Titan's photochemical model: Further update, oxygen species, and comparison with Triton and Pluto

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, V. A.

    2012-12-01

    The photochemical model for Titan's atmosphere and ionosphere is improved using the Troe approximation for termolecular reactions and inclusion of four radiative association reactions from those calculated by Vuitton et al. (2012). Proper fitting of eddy diffusion results in a reduction of the mean difference between 63 observed mixing ratios and their calculated values from a factor of 5 in our previous Titan's models to a factor of 3 in the current model. Oxygen chemistry on Titan is initiated by influxes of H2O from meteorites and O+ from magnetospheric interactions with the Saturn rings and Enceladus. Two versions of the model were calculated, with and without the O+ flux. Balances of CO, CO2, H2O, and H2CO are discussed in detail for both versions. The calculated model with the O+ flux agrees with the observations of CO, CO2, and H2O, including recent H2O CIRS limb observations and measurements by the Herschel Space Observatory. Major observational data and photochemical models for Triton and Pluto are briefly discussed. While the basic atmospheric species N2, CH4, and CO are similar on Triton and Pluto, properties of their atmospheres are very different with dominating atomic species and ions in Triton's upper atmosphere and ionosphere opposed to the molecular composition on Pluto. Calculations favor a transition between two types of photochemistry at the CH4 mixing ratio of ~5×10-4. Therefore the current Triton's photochemistry is still similar to that at the Voyager flyby despite the observed increase in N2 and CH4. The meteorite H2O results in precipitation of CO on Triton and CO2 on Pluto near perihelion. Main oxygen species on Titan: observations and the model. Solid lines show the model with both meteorite influx of H2O and magnetospheric flux of O+. Thin lines show the model without flux of O+. Observations: (1) CIRS (de Kok et al. 2007), (2) CIRS at 5°N (Vinatier et al. 2010), (3) ISO (Coustenis et al. 1998), (4) INMS (Cui et al., 2009), (5) CIRS

  6. Modelling the photochemical pollution over the metropolitan area of Porto Alegre, Brazil

    NASA Astrophysics Data System (ADS)

    Borrego, C.; Monteiro, A.; Ferreira, J.; Moraes, M. R.; Carvalho, A.; Ribeiro, I.; Miranda, A. I.; Moreira, D. M.

    2010-01-01

    The main purpose of this study is to evaluate the photochemical pollution over the Metropolitan Area of Porto Alegre (MAPA), Brazil, where high concentrations of ozone have been registered during the past years. Due to the restricted spatial coverage of the monitoring air quality network, a numerical modelling technique was selected and applied to this assessment exercise. Two different chemistry-transport models - CAMx and CALGRID - were applied for a summer period, driven by the MM5 meteorological model. The meteorological model performance was evaluated comparing its results to available monitoring data measured at the Porto Alegre airport. Validation results point out a good model performance. It was not possible to evaluate the chemistry models performance due to the lack of adequate monitoring data. Nevertheless, the model intercomparison between CAMx and CALGRID shows a similar behaviour in what concerns the simulation of nitrogen dioxide, but some discrepancies concerning ozone. Regarding the fulfilment of the Brazilian air quality targets, the simulated ozone concentrations surpass the legislated value in specific periods, mainly outside the urban area of Porto Alegre. The ozone formation is influenced by the emission of pollutants that act as precursors (like the nitrogen oxides emitted at Porto Alegre urban area and coming from a large refinery complex) and by the meteorological conditions.

  7. A photochemical model of the dust-loaded ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Cardnell, S.; Witasse, O.; Molina-Cuberos, G. J.; Michael, M.; Tripathi, S. N.; Déprez, G.; Montmessin, F.; O'Brien, K.

    2016-11-01

    The ionization of the lower Martian atmosphere and the presence of charged species are fundamental in the understanding of atmospheric electricity phenomena, such as electric discharges, large-scale electric currents, and Schumann resonances. The present photochemical model of the lower ionosphere of Mars (0-70 km) is developed to compute the concentration of the most abundant charged species (cluster ions, electrons, and charged aerosols) and electric conductivity, at the landing site and epoch of the ExoMars 2016 mission. The main sources of ionization are galactic cosmic rays (during daytime as well as nighttime) and photoionization of aerosols due to solar UV radiation during daytime. Ion and electron attachment to aerosols is another major source of aerosol charging. The steady state concentration of charged species is computed by solving their respective balance equations (also known as continuity equations), which include the source and sink terms of their photochemical reactions. Since the amount of suspended dust can vary considerably and it has an important effect on atmospheric properties, several dust scenarios, in addition to the day-night variations, are considered to characterize the variability of the concentration of charged species. It has been found that during daytime, aerosols tend to become positively charged due to electron photoemission and, during nighttime, tend to charge negatively due to electron attachment. The most dominant day-night variability in ion and electron concentration occurs when the amount of suspended dust is the largest. The electric conductivity has been found to vary in the 10-13-10-7 S/m range, depending on the altitude, dust scenario, and local time.

  8. 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

  9. 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.

  10. Relationship between Pulmonary Airflow and Resistance in Patients with Airway Narrowing Using An 1-D Network Resistance and Compliance Model

    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.

  11. Reducing the number of parameters in 1D arterial blood flow modeling: less is more for patient-specific simulations.

    PubMed

    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.

  12. Reducing the number of parameters in 1D arterial blood flow modeling: less is more for patient-specific simulations

    PubMed Central

    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

  13. Photochemical Modeling of CH3 Abundances in the Outer Solar System

    NASA Technical Reports Server (NTRS)

    Lee, Anthony Y. T.; Yung, Yuk L.; Moses, Julianne

    2000-01-01

    Recent measurements of methyl radicals (CH3) in the upper atmospheres of Saturn and Neptune by the Infrared Space Observatory (ISO) provide new constraints to photochemical models of hydrocarbon chemistry in the outer solar system. The derived column abundances of CH3 on Saturn above 10 mbar and Neptune above the 0.2 mbar pressure level are (2.5 - 6.0) x 10(exp 13) / sq cm and (0.7 - 2.8) x 10(exp 13) / sq cm, respectively. We use the updated Caltech/Jet Propulsion Laboratory photochemical model, which incorporates hydrocarbon photochemistry, vertical molecular and bulk atmospheric eddy diffusion, and realistic radiative transfer modeling, to study the CH3 abundances in the upper atmosphere of the giant planets and Titan. We identify the key reactions that control the concentrations of CH3 in the model, such as the three-body recombination reaction, CH3 + CH3 + M yields C2H6 + M. We evaluate and extrapolate the three-body rate constant of this reaction to the low-temperature limit (1.8 x 10(exp -16) T(sup -3.75) e(sup -300/T), T < 300 K) and compare methyl radical abundances in five atmospheres: Jupiter, Saturn, Uranus, Neptune, and Titan. The sensitivity of our models to the rate coefficients for the reactions H + CH3 + M yields CH4 + M, H + C2H3 yields C2H2 + H2, (sup 1)CH2 + H2 yields CH3 + H, and H + C2H5 yields 2CH3, the branching ratios of CH4 photolysis, vertical mixing in the five atmospheres, and Lyman alpha photon enhancement at the orbit of Neptune have all been tested. The results of our model CH3 abundances for both Saturn (5.1 x 10(exp 13) / sq cm) and Neptune (2.2 x 10(exp 13) / sq cm) show good agreement with ISO Short Wavelength Spectrometer measurements. Using the same chemical reaction set, our calculations also successfully generate vertical profiles of stable hydrocarbons consistent with Voyager and ground-based measurements in these outer solar system atmospheres. Predictions of CH3 column concentrations (for p <= 0.2 mbar) in the atmospheres

  14. 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

  15. 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.

  16. 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.

  17. Regional photochemical air quality modeling in the Mexico-US border area

    SciTech Connect

    Mendoza, A.; Russell, A.G.; Mejia, G.M.

    1998-12-31

    The Mexico-United States border area has become an increasingly important region due to its commercial, industrial and urban growth. As a result, environmental concerns have risen. Treaties like the North American Free Trade Agreement (NAFTA) have further motivated the development of environmental impact assessment in the area. Of particular concern are air quality, and how the activities on both sides of the border contribute to its degradation. This paper presents results of applying a three-dimensional photochemical airshed model to study air pollution dynamics along the Mexico-United States border. In addition, studies were conducted to assess how size resolution impacts the model performance. The model performed within acceptable statistic limits using 12.5 x 12.5 km{sup 2} grid cells, and the benefits using finer grids were limited. Results were further used to assess the influence of grid-cell size on the modeling of control strategies, where coarser grids lead to significant loss of information.

  18. The abundance, vertical distribution and origin of H2O in Titan’s atmosphere: Herschel observations and photochemical modelling

    NASA Astrophysics Data System (ADS)

    Moreno, Raphael; Lellouch, Emmanuel; Lara, Luisa M.; Feuchtgruber, Helmut; Rengel, Miriam; Hartogh, Paul; Courtin, Régis

    2012-11-01

    Disk-averaged observations of water vapor in Titan’s atmosphere acquired with the Herschel satellite are reported. We use a combination of unresolved measurements of three H2O rotational lines at 66.4, 75.4 and 108.0 μm with the PACS instrument, and spectrally-resolved observations of two other transitions at 557 GHz (538 μm) and 1097 GHz (273 μm) with the HIFI instrument, to infer the vertical profile of H2O over the 100-450 km altitude range. Monitoring of the 66.4 μm line indicates no variation between Titan leading and trailing sides, nor variation over a ∼1 year interval. Both the narrow (2-4 MHz) widths of the HIFI-observed lines, and the relative contrasts of the five H2O lines indicate that the H2O mole fraction strongly increases with altitude, with a best fit mole fraction of q0 = (2.3 ± 0.6) × 10-11 at a pressure p = 12.1 mbar, a slope -d(ln q)/d(ln p) = 0.49 ± 0.07, and a H2O column density of (1.2+/-0.2) × 1014 cm-2. This H2O profile also matches the original ISO observations of Titan H2O. Water vertical profiles previously proposed on the basis of 1-D photochemical models are too water-rich, and none of them have the adequate slope; in particular, the water profiles of Lara et al. (Lara, L.M., Lellouch, E., López-Moreno, J.J., Rodrigo, R. [1996]. J. Geophys. Res. E 101, 23261-23283) and Hörst et al. (Hörst, S.M., Vuitton, V., Yelle, R.V. [2008]. J. Geophys. Res. E 113, E10006) are too steep and too shallow, respectively, in the lower stratosphere. Photochemical models of oxygen species in Titan’s atmosphere are reconsidered, updating the Lara et al. model for oxygen chemistry, and adjusting the eddy diffusion coefficient in order to match both our H2O observations and the C2H6 and C2H2 vertical profiles determined from Cassini/CIRS. We find that the H2O profile can be reproduced by invoking a OH/H2O influx of (2.7-3.4) × 105 mol cm-2 s-1, referred to the surface. This is essentially one order of magnitude lower than invoked by

  19. Photochemical grid model implementation and application of VOC, NOx, and O3 source apportionment

    EPA Science Inventory

    For the purposes of developing optimal emissions control strategies, efficient approaches are needed to identify the major sources or groups of sources that contribute to elevated ozone (O3) concentrations. Source-based apportionment techniques implemented in photochemical grid m...

  20. Discovery of photochemical damage mechanisms using in vitro and in silico models

    NASA Astrophysics Data System (ADS)

    Fink, Pamela K.; Denton, Michael L.; Castellanos, Cherry C.; Tijerina, Amanda J.; Schuster, Kurt J.; Oliver, Jeffrey W.

    2013-02-01

    A computer-based model has been built that simulates the response of the retinal pigmented epithelial (RPE) cell to laser exposure in the photochemical (non-thermal) damage exposure range (>= 100 s exposures). The modeling approach used is knowledge-based, modular, and hierarchical, allowing the explicit modeling of the cascades of intracellular events in response to laser application. Thus, the model can be used to both analyze existing in vitro data sets, as well as efficiently direct sampling strategies for future in vitro and in vivo studies. This model has been validated using laboratory data from several studies reported in the literature using blue light (413 nm and 458 nm) lasers with 100 s, 200 s, and 3600 s exposure durations. The model was able to predict the in vitro ED50 response curve from these studies, as well as the results for which we have no in vitro data (extrapolated based on irradiance reciprocity), within 1-6% for the shorter duration exposures. Based on exploration of this computer model using lethal vs. non-lethal laser exposure scenarios, the RPE cell's oxidative stress response differs quantitatively very little with respect to typical oxidative stress sources such as superoxide and hydrogen peroxide. However, in the lethal exposure scenarios the model points to a potential tipping point in the oxidative stress response of the mitochondrial-based cellular energetics. Further studies are underway to explore issues related to the levels of ATP/ADP and GSH/GSSG that are predicted by the model in these lethal vs. non-lethal exposure scenarios.

  1. ABSTRACTION OF INFORMATION FROM 2- AND 3-DIMENSIONAL PORFLOW MODELS INTO A 1-D GOLDSIM MODEL - 11404

    SciTech Connect

    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

  2. 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

  3. Model study of the photochemical rearrangement pathways of 1,2,4-oxadiazole.

    PubMed

    Su, Ming-Der

    2014-09-15

    The mechanisms of photochemical isomerization reactions are investigated theoretically by using a model system of 1,2,4- oxadiazole with the CAS(14,9)/6-311G(d) and MP2-CAS-(14,9)/ 6-311++G(3df,3pd)//CAS(14,9)/6-311G(d) methods. Three reaction pathways are examined, including 1) the direct mechanism, 2) the ring contraction-ring expansion mechanism, and 3) the internal cyclization-isomerization mechanism, which lead to two types of photoisomers. The theoretical findings suggest that conical intersections play a crucial role in the photorearrangement of 1,2,4-oxadiazoles. These model investigations also indicate that the preferred reaction route for 1,2,4-oxadiazole, which leads to phototransposition products, is as follows: reactant → Franck-Condon region → conical intersection → photoproduct. In other words, the direct mechanism is a one-step process that has no barrier. These theoretical results agree with the available experimental observations.

  4. 1-D seismic velocity model and hypocenter relocation using double difference method around West Papua region

    SciTech Connect

    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.

  5. A One-Dimensional (1-D) Three-Region Model for a Bubbling Fluidized-Bed Adsorber

    SciTech Connect

    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.

  6. Outdoor smog chamber experiments to test photochemical models. Final report May 78-May 81

    SciTech Connect

    Feffries, H.E.; Kamens, R.M.; Sexron, K.G.; Gerhardt, A.A.

    1982-04-01

    The smog chamber facility of the University of North Carolina was used in a study to provide experimental data for developing and testing kinetic mechanisms of photochemical smog formation. The smog chamber, located outdoors in rural North Carolina, is an A-frame structure covered with Teflon film. Because the chamber is partitioned into two sections, each with a volume of 156 cu m, two experiments can be conducted simultaneously. The dual chamber is operated under natural conditions of solar radiation, temperature, and relative humidity. In this study, 115 dual all-day experiments were conducted using NOx and a variety of organic species. The organic compounds investigated included various paraffins, olefins, aromatics and oxygenates, both singly and in mixtures of two or more components. In this report the data collected over the three-year period of the study are described. The experimental procedures and analytical methods used in this study and the limitations and uncertainties of the data are discussed. Guidance for modeling of the data is also given, including a detailed discussion of how to estimate photolytic rate constants from the available UV and total solar radiation data and how to treat such chamber artifacts as dilution, wall sources and losses of pollutants, and reactivity of the background air.

  7. The Social Network of Tracer Variations and O(100) Uncertain Photochemical Parameters in the Community Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Lucas, D. D.; Labute, M.; Chowdhary, K.; Debusschere, B.; Cameron-Smith, P. J.

    2014-12-01

    Simulating the atmospheric cycles of ozone, methane, and other radiatively important trace gases in global climate models is computationally demanding and requires the use of 100's of photochemical parameters with uncertain values. Quantitative analysis of the effects of these uncertainties on tracer distributions, radiative forcing, and other model responses is hindered by the "curse of dimensionality." We describe efforts to overcome this curse using ensemble simulations and advanced statistical methods. Uncertainties from 95 photochemical parameters in the trop-MOZART scheme were sampled using a Monte Carlo method and propagated through 10,000 simulations of the single column version of the Community Atmosphere Model (CAM). The variance of the ensemble was represented as a network with nodes and edges, and the topology and connections in the network were analyzed using lasso regression, Bayesian compressive sensing, and centrality measures from the field of social network theory. Despite the limited sample size for this high dimensional problem, our methods determined the key sources of variation and co-variation in the ensemble and identified important clusters in the network topology. Our results can be used to better understand the flow of photochemical uncertainty in simulations using CAM and other climate models. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the DOE Office of Science through the Scientific Discovery Through Advanced Computing (SciDAC).

  8. Glut1 deficiency (G1D): Epilepsy and metabolic dysfunction in a mouse model of the most common human phenotype

    PubMed Central

    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

  9. An evaluation of 1D loss model collections for the off-design performance prediction of automotive turbocharger compressors

    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.

  10. Photochemical Modeling of the Distribution of C3H8 in the Atmosphere of Saturn

    NASA Astrophysics Data System (ADS)

    Edgington, S. G.; Simon-Miller, A.; Jennings, D.; Bjoraker, G.; Romani, P.; Achterberg, R.; Orton, G.; Flasar, M.; Cassini CIRS Team

    2005-08-01

    Cassini's Composite Infrared Spectrometer (CIRS) has measured the abundance of C2H2 and C3H8 (Propane) at several latitudes in the Southern hemisphere. An increase of radiance with latitude towards the pole has been observed, possibly implying a corresponding increase of C3H8. In an effort explain the observed distribution of both species, it is important to model the creation, destruction, and transport of these chemical species. Furthermore, since both molecules have overlapping absorption features in the same spectral region near 748 cm-1, such modeling will aid in refining derived abundances and separating temperature effects. The photochemistry model used in Edgington et al. (1998, 1999, 2000) to model simultaneously hydrocarbons, ammonia, and phosphine is updated and expanded to include paths relevant to the creation of C3H8. Destruction occurs through photolysis, while transport would tend to spread C3H8 from its source regions. With a series of exercises in 1- and 2- dimensions, we explore the extent to which photolysis, vertical, and/or meridional transport impacts the distribution of C2H2 and C3H8 with latitude. Thermal profiles derived from CIRS observations versus latitude are used as they have an impact on numerous reaction rates. We then compare these results with abundances derived from observations taken with the CIRS instrument. Edgington, S.G., West, R.A., Friedson, A.J., Atreya, S.K., 2000. A 2-D photochemical model with meridional circulation. Bull. American. Astron. Soc., 32, 1013. Edgington, S.G., S.K. Atreya, L.M. Trafton, J.J. Caldwell, R.F. Beebe, A.A. Simon, and R.A. West, 1999. Ammonia and eddy mixing variations in the southern hemisphere of Jupiter from HST Faint Object Spectrograph Observations. Icarus, 142, 342-357. Edgington, S.G., S.K. Atreya, L.M. Trafton, J.J. Caldwell, R.F. Beebe, A.A. Simon, R.A. West, and C. Barnet, 1998. On the latitude variation of ammonia, acetylene, and phosphine altitude profiles on Jupiter from HST Faint

  11. Spectroscopic Studies on the Photochemical transformation of Tannic Acid as a Model for HULIS in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Cowen, S.; Al-Abadleh, H. A.

    2009-05-01

    Little is known about the photochemical transformation of humic like substances (HULIS) in atmospheric aerosols, and the role of adsorbed water and photosensitizers in this photochemistry. We present in-situ and surface-sensitive spectroscopic studies on the photochemical transformation of tannic acid in the absence and presence of sodium nitrite salt. Tannic acid was chosen as a synthetic proxy for HULIS because it has a defined molecular structure with elemental composition similar to that determined for atmospheric HULIS. Photochemical studies were conducted using diffuse reflectance infrared spectroscopy (DRIFTS) as a function of time (3 hrs), relative humidity (5-50%) and total irradiance (7-100 Wm-2). DRIFTS has proven to be a powerful tool for studying the heterogeneous chemistry of model components in aerosols. Preliminary spectral results show loss and growth features suggesting bonds breakage and formation of carboxylate or organic nitrogen species. The growth of the band assigned to the bending mode of water with irradiation time was also observed and suggests an increase in the hydrophilicity of tannic acid. The structure of water adsorbed on tannic acid resembles that of water at the interface with organic solvents. The implication of these results to the field of aerosols aging due to photochemistry will be discussed.

  12. A PHOTOCHEMICAL MODEL FOR THE CARBON-RICH PLANET WASP-12b

    SciTech Connect

    Kopparapu, Ravi kumar; Kasting, James F.; Zahnle, Kevin J.

    2012-01-20

    The hot-Jupiter WASP-12b is a heavily irradiated exoplanet in a short-period orbit around a G0-star with twice the metallicity of the Sun. A recent thermochemical equilibrium analysis based on Spitzer and ground-based infrared observations suggests that the presence of CH{sub 4} in its atmosphere and the lack of H{sub 2}O features can only be explained if the carbon-to-oxygen ratio in the planet's atmosphere is much greater than the solar ratio ([C]/[O] = 0.54). Here, we use a one-dimensional photochemical model to study the effect of disequilibrium chemistry on the observed abundances of H{sub 2}O, CO, CO{sub 2}, and CH{sub 4} in the WASP-12b atmosphere. We consider two cases: one with solar [C]/[O] and another with [C]/[O] = 1.08. The solar case predicts that H{sub 2}O and CO are more abundant than CO{sub 2} and CH{sub 4}, as expected, whereas the high [C]/[O] model shows that CO, C{sub 2}H{sub 2}, and HCN are more abundant. This indicates that the extra carbon from the high [C]/[O] model is in hydrocarbon species. H{sub 2}O photolysis is the dominant disequilibrium mechanism that alters the chemistry at higher altitudes in the solar [C]/[O] case, whereas photodissociation of C{sub 2}H{sub 2} and HCN is significant in the super-solar case. Furthermore, our analysis indicates that C{sub 2}H{sub 2} is the major absorber in the atmosphere of WASP-12b and the absorption features detected near 1.6 and 8 {mu}m may be arising from C{sub 2}H{sub 2} rather than CH{sub 4}. The Hubble Space Telescope's WFC3 can resolve this discrepancy, as C{sub 2}H{sub 2} has absorption between 1.51 and 1.54 {mu}m, while CH{sub 4} does not.

  13. 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.

  14. Computer modeling of simulated photochemical smog. Final report, Sep 77-Aug 79

    SciTech Connect

    Hendry, D.G.; Baldwin, A.C.; Golden, D.M.

    1980-02-01

    Efforts to develop chemical kinetic mechanisms to describe the formation of photochemical smog are discussed. Detailed mechanisms for the atmospheric reactions of toluene, m-xylene, propene, ethene, formaldehyde and acetaldehyde were constructed from available experimental and chemical kinetic data. These mechanisms were used to simulate smog chamber data from the Statewide Air Pollution Research Center at the University of California, Riverside and the outdoor facility of the University of North Carolina.

  15. A fast hybrid (3-D/1-D) model for thermal radiative transfer in cirrus via successive orders of scattering

    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.

  16. A Fast Hybrid (3-D/1-D) Model for Thermal Radiative Transfer in Cirrus via Successive Orders of Scattering

    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.

  17. 1-D and 2-D resonances in an Alpine valley identified from ambient noise measurements and 3-D modelling

    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.

  18. 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.

  19. 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

  20. Bottom Roughness and Bathymetry Estimation of 1-D Shallow Water Equations Model Using Ensemble Kalman Filter

    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

  1. 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

  2. Simulating the density of HC15N in the Titan atmosphere with a coupled ion-neutral photochemical model

    NASA Astrophysics Data System (ADS)

    Vuitton, V.; Yelle, R. V.; Klippenstein, S. J.; Lavvas, P.; Hörst, S. M.

    2015-10-01

    The 14 N/ 15 N ratio for HCN in the atmosphere of Titan has been measured to be 2 to 3 times as less as the corresponding ratio for N2. Using a coupled ionneutral photochemical model incorporating state-of-the-art chemistry and cross-sections for N2, we show that the difference in the ratio of 14 N/15 N between HCN and N2 can be explained exclusively by the photo-induced isotopic fractionation of 14 N14 N and 14 N 15 N,without any further putative nitrogen input.

  3. RANS computations for identification of 1-D cavitation model parameters: application to full load cavitation vortex rope

    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.

  4. Impact of sea spray on upper ocean temperature during typhoon passage: simulation with a 1-D turbulent model

    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.

  5. Radon exhalation from uranium mill tailings: experimental validation of a 1-D model.

    PubMed

    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.

  6. Evidence for an increase in the ozone photochemical lifetime in the eastern United States using a regional air quality model

    NASA Astrophysics Data System (ADS)

    Goldberg, Daniel L.; Vinciguerra, Timothy P.; Hosley, Kyle M.; Loughner, Christopher P.; Canty, Timothy P.; Salawitch, Ross J.; Dickerson, Russell R.

    2015-12-01

    Measures to control surface ozone rely on quantifying production attributable to local versus regional (upwind) emissions. Here we simulate the relative contribution of local (i.e., within a particular state) and regional sources of surface ozone in the eastern United States (66-94°W longitude) for July 2002, 2011, and 2018 using the Comprehensive Air-quality Model with Extensions (CAMx). To determine how emissions and chemistry within the domain affect the production, loss, lifetime, and transport of trace gases, we initialize our model with identical boundary conditions in each simulation. We find that the photochemical lifetime of ozone has increased as emissions have decreased. The contribution of ozone from outside the domain (boundary condition ozone, BCO3) to local surface mixing ratios increases in an absolute sense by 1-2 ppbv between 2002 and 2018 due to the longer lifetime of ozone. The photochemical lifetime of ozone lengthens because the two primary gas phase sinks for odd oxygen (Ox ≈ NO2 + O3)—attack by hydroperoxyl radicals (HO2) on ozone and formation of nitrate—weaken with decreasing pollutant emissions. The relative role of BCO3 will also increase. For example, BCO3 represents 34.5%, 38.8%, and 43.6% of surface ozone in the Baltimore, MD, region during July 2002, 2011, and 2018 means, respectively. This unintended consequence of air quality regulation impacts attainment of the National Ambient Air Quality Standard for surface ozone because the spatial and temporal scales of photochemical smog increase; the influence of pollutants transported between states and into the eastern U.S. will likely play a greater role in the future.

  7. 2D MHD AND 1D HD MODELS OF A SOLAR FLARE—A COMPREHENSIVE COMPARISON OF THE RESULTS

    SciTech Connect

    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.

  8. Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

    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.

  9. Development and validation of THUMS version 5 with 1D muscle models for active and passive automotive safety research.

    PubMed

    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.

  10. 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.

  11. 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).

  12. A box model study on photochemical interactions between VOCs and reactive halogen species in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Toyota, K.; Kanaya, Y.; Takahashi, M.; Akimoto, H.

    2004-09-01

    A new chemical scheme is developed for the multiphase photochemical box model SEAMAC (size-SEgregated Aerosol model for Marine Air Chemistry) to investigate photochemical interactions between volatile organic compounds (VOCs) and reactive halogen species in the marine boundary layer (MBL). Based primarily on critically evaluated kinetic and photochemical rate parameters as well as a protocol for chemical mechanism development, the new scheme has achieved a near-explicit description of oxidative degradation of up to C3-hydrocarbons (CH4, C2H6, C3H8, C2H4, C3H6, and C2H2) initiated by reactions with OH radicals, Cl- and Br-atoms, and O3. Rate constants and product yields for reactions involving halogen species are taken from the literature where available, but the majority of them need to be estimated. In particular, addition reactions of halogen atoms with alkenes will result in forming halogenated organic intermediates, whose photochemical loss rates are carefully evaluated in the present work. Model calculations with the new chemical scheme reveal that the oceanic emissions of acetaldehyde (CH3CHO) and alkenes (especially C3H6) are important factors for regulating reactive halogen chemistry in the MBL by promoting the conversion of Br atoms into HBr or more stable brominated intermediates in the organic form. The latter include brominated hydroperoxides, bromoacetaldehyde, and bromoacetone, which sequester bromine from a reactive inorganic pool. The total mixing ratio of brominated organic species thus produced is likely to reach 10-20% or more of that of inorganic gaseous bromine species over wide regions over the ocean. The reaction between Br atoms and C2H2 is shown to be unimportant for determining the degree of bromine activation in the remote MBL. These results imply that reactive halogen chemistry can mediate a link between the oceanic emissions of VOCs and the behaviors of compounds that are sensitive to halogen chemistry such as dimethyl sulfide, NOx, and

  13. A box model study on photochemical interactions between VOCs and reactive halogen species in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Toyota, K.; Kanaya, Y.; Takahashi, M.; Akimoto, H.

    2003-09-01

    A new chemical scheme is developed for the multiphase photochemical box model SEAMAC (size-SEgregated Aerosol model for Marine Air Chemistry) to investigate photochemical interactions between volatile organic compounds (VOCs) and reactive halogen species in the marine boundary layer (MBL). Based primarily on critically evaluated kinetic and photochemical rate parameters as well as a protocol for chemical mechanism development, the new scheme has achieved a near-explicit treatment of oxidative degradation of up to C3-hydrocarbons CH4, C2H6, C3H8, C2H4, C3H6, and C2H2) initiated by reactions with OH radicals, Cl- and Br-atoms, and O3. Rate constants and product yields for reactions involving halogen species are taken from the literature where available, but the majority of them need to be estimated. In particular, addition reactions of halogen atoms with alkenes will result in the formation of halogenated organic intermediates, whose photochemical loss rates are carefully evaluated in the present work. Model calculations with the new chemical scheme reveal that the oceanic emissions of acetaldehyde (CH3CHO) and alkenes (especially C3H6) are important factors for regulating reactive halogen chemistry in the MBL by promoting the conversion of Br atoms into HBr or more stable brominated intermediates in the organic form. The latter include brominated hydroperoxides, bromoacetaldehyde, and bromoacetone, which sequester bromine from reactive inorganic pool. The total mixing ratio of brominated organic species thus produced is likely to reach 10-20% or more of that of inorganic gaseous bromine species over wide regions over the ocean. On the other hand, the reaction between Br atoms and C2H2 is unimportant for determining the degree of bromine activation in the remote MBL. It is suggested that peroxyacetic acid formed via CH3CHO oxidation is one of the important chemical agents for triggering autocatalytic halogen release from sea-salt aerosols. These results imply that

  14. 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

  15. 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.

  16. 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).

  17. 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.

  18. Constraining quantum critical dynamics: (2+1)D Ising model and beyond.

    PubMed

    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.

  19. The Sensitivity of Model Ozone to Advective and Photochemical Processes in the High Latitude Winter Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Douglass, A.; Kawa, S. R.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Three dimensional chemistry and transport models (CTMs) contain a set of coupled continuity equations which describe the evolution of constituents such as ozone and other minor species which affect ozone. Both advection and photochemical processes contribute to constituent evolution, and a CTM provides a means to evaluate these contributions separately. Such evaluation is particularly useful when both terms are important to the modeled tendency. An example is the ozone tendency in the high latitude winter lower stratosphere, where advection tends to increase ozone, and catalytic processes involving chlorine radicals tend to decrease ozone. The Goddard three dimensional chemistry and transport model uses meteorological fields from the Goddard Earth Observing System Data Assimilation System, thus the modeled ozone evolution may reproduce the observed evolution and provide a test of the model representation of photochemical processes if the transport is shown to be modeled appropriately. We have investigated the model advection further using diabatic trajectory calculations. For long lived constituents such as N2O, the model field for a particular time on a potential temperature surface is compared with a field produced by calculating 15 day back trajectories for a fixed latitude longitude grid, and mapping model N2O at the terminus of the back trajectories onto the initial grid. This provides a quantitative means to evaluate two aspects of the CTM transport: one, the model horizontal gradient between middle latitudes and the polar vortex is compared with the gradient produced using the non-diffusive trajectory calculation; two, the model vertical advection, which is produced by the divergence of the horizontal winds, is compared with the vertical transport expected from diabatic cooling.

  20. 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.

  1. Modeling of the Plasma Electrode Bias in the Negative Ion Sources with 1D PIC Method

    SciTech Connect

    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.

  2. Hyperbolic reformulation of a 1D viscoelastic blood flow model and ADER finite volume schemes

    SciTech Connect

    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.

  3. 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

  4. 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.

  5. 1-D transient numerical model of a regenerator in a novel sub Kelvin Active Magnetic Regenerative Refrigerator

    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.

  6. 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.

  7. Using 1D2D Hydrodynamic Modeling to Inform Restoration Planning in the Atchafalaya River Basin, Louisiana

    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.

  8. A 1D pulse wave propagation model of the hemodynamics of calf muscle pump function

    PubMed Central

    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

  9. Applying model simulation and photochemical indicators to evaluate ozone sensitivity in southern Taiwan.

    PubMed

    Peng, Yen-Ping; Chen, Kang-Shin; Wang, Hsin-Kai; Lai, Chia-Hsiang; Lin, Ming-Hsun; Lee, Cheng-Haw

    2011-01-01

    Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites (Pingtung City, Chao-Chou Town, and Kenting Town) in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds (VOC)-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators (H2O2, HNO3, and NOy) were conducted, and simulated three transition ranges of H2O2/HNO3 (0.5-0.8), O3/HNO3 (10.3-16.2) and O3/NOy (5.7-10.8) were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.

  10. LETTER TO THE EDITOR: Coarsening in the 1D Ising model evolving with Swendsen - Wang dynamics: an unusual scaling

    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.

  11. Assessment of phenol infiltration resilience in soil media by HYDRUS-1D transport model for a waste discharge site.

    PubMed

    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

  12. Modelling photochemical pollutants in a deep urban street canyon: Application of a coupled two-box model approximation

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; Cai, Xiao-Ming; Bloss, William James

    2016-10-01

    Air pollution associated with road transport is a major environmental issue in urban areas. Buildings in urban areas are the artificial obstacles to atmospheric flow and cause reduced ventilation for street canyons. For a deep street canyon, there is evidence of the formation of multiple segregated vortices, which generate flow regimes such that pollutants exhibit a significant contrast between these vortices. This results in poor air ventilation conditions at pedestrian level, thereby leading to elevated pollutant levels and potential breaches of air quality limits. The hypothesis of a well-mixed deep street canyon in the practical one-box model approach is shown to be inappropriate. This study implements a simplified simulation of the canyon volume: a coupled two-box model with a reduced chemical scheme to represent the key photochemical processes with timescales similar to and smaller than the turbulent mixing timescale. The two-box model captures the significant pollutant contrast between the lower and upper parts of a deep street canyon, particularly for NO2. Core important parameters (i.e. heterogeneity coefficient, exchange velocity and box height ratio) in the two-box model approach were investigated through sensitivity tests. The two-box model results identify the emission regimes and the meteorological conditions under which NO2 in the lower canyon (i.e. the region of interest for the assessment of human health effects) is in breach of air quality standards. Higher NO2 levels were observed for the cases with higher heterogeneity coefficients (the two boxes are more segregated), with lower exchange velocities (worse ventilation conditions), or with smaller box height ratios (reduced dilution possibly due to secondary smaller eddies in the lower canyon). The performance of a one-box model using the same chemical scheme is also evaluated against the two-box model. The one-box model was found to systematically underestimate NO2 levels compared with those in

  13. Geometric and frequency EMI sounding of estuarine earthen flood defence embankments in Ireland using 1D inversion models

    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.

  14. Photochemical modeling in California with two chemical mechanisms: model intercomparison and response to emission reductions.

    PubMed

    Cai, Chenxia; Kelly, James T; Avise, Jeremy C; Kaduwela, Ajith P; Stockwell, William R

    2011-05-01

    An updated version of the Statewide Air Pollution Research Center (SAPRC) chemical mechanism (SAPRC07C) was implemented into the Community Multiscale Air Quality (CMAQ) version 4.6. CMAQ simulations using SAPRC07C and the previously released version, SAPRC99, were performed and compared for an episode during July-August, 2000. Ozone (O3) predictions of the SAPRC07C simulation are generally lower than those of the SAPRC99 simulation in the key areas of central and southern California, especially in areas where modeled concentrations are greater than the federal 8-hr O3 standard of 75 parts per billion (ppb) and/or when the volatile organic compound (VOC)/nitrogen oxides (NOx) ratio is less than 13. The relative changes of ozone production efficiency (OPE) against the VOC/NOx ratio at 46 sites indicate that the OPE is reduced in SAPRC07C compared with SAPRC99 at most sites by as much as approximately 22%. The SAPRC99 and SAPRC07C mechanisms respond similarly to 20% reductions in anthropogenic VOC emissions. The response of the mechanisms to 20% NOx emissions reductions can be grouped into three cases. In case 1, in which both mechanisms show a decrease in daily maximum 8-hr O3 concentration with decreasing NOx emissions, the O3 decrease in SAPRC07C is smaller. In case 2, in which both mechanisms show an increase in O3 with decreasing NOx emissions, the O3 increase is larger in SAPRC07C. In case 3, SAPRC07C simulates an increase in O3 in response to reduced NOx emissions whereas SAPRC99 simulates a decrease in O3 for the same region. As a result, the areas where NOx controls would be disbeneficial are spatially expanded in SAPRC07C. Although the results presented here are valuable for understanding differences in predictions and model response for SAPRC99 and SAPRC07C, the study did not evaluate the impact of mechanism differences in the context of the U.S. Environmental Protection Agency's guidance for using numerical models in demonstrating air quality attainment

  15. Determinants of modelling choices for 1-D free-surface flow and morphodynamics in hydrology and hydraulics: a review

    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.

  16. Natural hydrocarbon emission estimates based on Landsat data as an input to a regional ozone photochemical model

    NASA Technical Reports Server (NTRS)

    Middleton, E. M.; Gervin, J. C.; Salop, J.

    1982-01-01

    Landsat-derived forest cover data were employed with non-methane hydrocarbon (NMHC) emission rates in a model to quantify summer forest ozone production for the Tidewater Region of Virginia. The areal extent of the three major forest types - coniferous, deciduous, and mixed - were determined from Landsat data on two adjacent scenes, using an unsupervised approach to spectral signature development. The forest type results from both data sets were verified in an extensive accuracy assessment and merged to provide regional statistics for total acreages, percent forest, and error rates. The Landsat statistics were incorporated into forest type emission factor equations to produce an estimated emission rate for natural hydrocarbons from forests. This estimate, along with measured rates for nitrogen oxides and NMHC from anthropogenic sources, was provided as input to computer simulations of atmospheric ozone generation for the Tidewater Region using a photochemical oxident model.

  17. 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.

  18. Giant Fluctuations of Local Magnetoresistance of Organic Spin Valves and the Non-Hermitian 1D Anderson Model

    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.

  19. Understanding the colloidal dispersion stability of 1D and 2D materials: Perspectives from molecular simulations and theoretical modeling.

    PubMed

    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.

  20. Photochemical modeling of the Antarctic stratosphere: Observational constraints from the airborne Antarctic ozone experiment and implications for ozone behavior

    NASA Technical Reports Server (NTRS)

    Rodriguez, Jose M.; Sze, Nien-Dak; Ko, Malcolm K. W.

    1988-01-01

    The rapid decrease in O3 column densities observed during Antarctic spring has been attributed to several chemical mechanisms involving nitrogen, bromine, or chlorine species, to dynamical mechanisms, or to a combination of the above. Chlorine-related theories, in particular, predict greatly elevated concentrations of ClO and OClO and suppressed abundances of NO2 below 22 km. The heterogeneous reactions and phase transitions proposed by these theories could also impact the concentrations of HCl, ClNO3 and HNO3 in this region. Observations of the above species have been carried out from the ground by the National Ozone Expedition (NOZE-I, 1986, and NOZE-II, 1987), and from aircrafts by the Airborne Antarctic Ozone Experiment (AAOE) during the austral spring of 1987. Observations of aerosol concentrations, size distribution and backscattering ratio from AAOE, and of aerosol extinction coefficients from the SAM-II satellite can also be used to deduce the altitude and temporal behavior of surfaces which catalyze heterogeneous mechanisms. All these observations provide important constraints on the photochemical processes suggested for the spring Antarctic stratosphere. Results are presented for the concentrations and time development of key trace gases in the Antarctic stratosphere, utilizing the AER photochemical model. This model includes complete gas-phase photochemistry, as well as heterogeneous reactions. Heterogeneous chemistry is parameterized in terms of surface concentrations of aerosols, collision frequencies between gas molecules and aerosol surfaces, concentrations of HCl/H2O in the frozen particles, and probability of reaction per collision (gamma). Values of gamma are taken from the latest laboratory measurements. The heterogeneous chemistry and phase transitions are assumed to occur between 12 and 22 km. The behavior of trace species at higher altitudes is calculated by the AER 2-D model without heterogeneous chemistry. Calculations are performed for

  1. 1D Modeling of the Initial Stage of Wire Explosions and 2D Modeling of the m=0 Sausage Instability With Sheared Axial Flow

    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.

  2. 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.

  3. Catalysis of Photochemical Reactions.

    ERIC Educational Resources Information Center

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  4. A Generic 1D Forward Modeling and Inversion Algorithm for TEM Sounding with an Arbitrary Horizontal Loop

    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.

  5. Satellite-derived light extinction coefficient and its impact on thermal structure simulations in a 1-D lake model

    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.

  6. Interpretation of MSL REMS data using 1D coupled heat and water vapor transport model of Mars subsurface

    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.

  7. Scale up tools in reactive extrusion and compounding processes. Could 1D-computer modeling be helpful?

    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.

  8. Limb darkening laws for two exoplanet host stars derived from 3D stellar model atmospheres. Comparison with 1D models and HST light curve observations

    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

  9. Impact of Mars Water Ice Clouds and Thermal Aerosol Enforcement to the Shortscale Climate Dynamics: Evidence from 1-D Model

    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.

  10. 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.

  11. A reduced-order model based on the coupled 1D-3D finite element simulations for an efficient analysis of hemodynamics problems

    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.

  12. Photochemical Internalization of Bleomycin Before External-Beam Radiotherapy Improves Locoregional Control in a Human Sarcoma Model

    SciTech Connect

    Norum, Ole-Jacob; Bruland, Oyvind Sverre; Gorunova, Ludmila; Berg, Kristian

    2009-11-01

    Purpose: The aim of this study was to explore the tumor growth response of the combination photochemical internalization and external-beam radiotherapy. Photochemical internalization is a technology to improve the utilization of therapeutic macromolecules in cancer therapy by photochemical release of endocytosed macromolecules into the cytosol. Methods and Materials: A human sarcoma xenograft TAX-1 was inoculated subcutaneously into nude mice. The photosensitizer AlPcS{sub 2a} and bleomycin were intraperitoneally administrated 48 h and 30 min, respectively, before diode laser light exposure at 670 nm (20 J/cm{sup 2}). Thirty minutes or 7 days after photochemical treatment, the animals were subjected to 4 Gy of ionizing radiation. Results: Using photochemical internalization of bleomycin as an adjunct to ionizing radiation increased the time to progression for the tumors from 17 to 33 days as compared with that observed with photodynamic therapy combined with ionizing radiation as well as for radiochemotherapy with bleomycin. The side effects observed when photochemical internalization of bleomycin was given shortly before ionizing radiation were eliminated by separating the treatment modalities in time. Conclusion: Photochemical internalization of bleomycin combined with ionizing radiation increased the time to progression and showed minimal toxicity and may therefore reduce the total radiation dose necessary to obtain local tumor control while avoiding long-term sequelae from radiotherapy.

  13. A two-dimensional photochemical model of the atmosphere. I Chlorocarbon emissions and their effect on stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Gidel, L. T.; Crutzen, P. J.; Fishman, J.

    1983-01-01

    A two-dimensional photochemical model is used to examine changes to the ozone layer caused by emissions of CFCl3, CF2Cl2, CH3CCl3 and CCl4. The influence of a possible secular increase in tropospheric methane up to 2 percent per year was found to be small, although it acts to mask decreases in total ozone caused by the chlorocarbons. Increasing NO(x) emissions caused by industralization also tend to mask decreases in total ozone and may have caused total ozone to increase by about 1 percent. The model-calculated ozone decreases are estimated to be about 3 percent by 1980. This estimate is higher than estimates by similar models, although it is noted that CCl4 and CH3CCl3 emissions are included in the model in addition to CFCl3 and CF2Cl2. This is significant because the model indicates that CCl4 has dominated the ozone depletions so far, and knowledge of the historical emission rate of CCl4 to the atmosphere is incomplete. There remain sufficient significant disagreements between theoretical and observed concentrations and variabilities, particularly for odd nitrogen and ClO, to caution against assigning too much confidence in the calculated ozone depletion.

  14. A 1D-ecosystem model for pelagic waters in the southern Baltic Sea. Numerical simulations (future decades)

    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.

  15. Automatic 1D integrated geophysical modelling of lithospheric discontinuities: a case study from Carpathian-Pannonian Basin region

    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

  16. A numerical method of reduced complexity for simulating vascular hemodynamics using coupled 0D lumped and 1D wave propagation models.

    PubMed

    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.

  17. Combined effects of organic reactivity and NMHC/NO x ratio on photochemical oxidant formation—a modeling study

    NASA Astrophysics Data System (ADS)

    Dodge, Marcia C.

    A modeling study was undertaken to assess the effect of organic reactivity on photochemical oxidant formation. A six-component hydrocarbon model was developed and tested against data collected in a smog chamber study of irradiated auto exhaust and oxides of nitrogen (NO x) mixtures. The model was then adjusted to conditions that more closely approximated those of the urban environment. The adjusted model was used to assess the relative reactivity of various organic constituents when present in an urban-like air mass. Twelve organics were investigated in the study: ethane, propane, n-butane, ethylene, propylene, trans-2-butene, toluene, m-xylene, methanol, ethanol, formaldehyde and acetaldehyde. The findings of this study indicate that the reactivity of organics depends strongly on the hydrocarbon-to-NO x ratio of the mix in which they are reacting. At low hydrocarbon-to-NO x ratios, the organics investigated in this study displayed significantly different O 3-forming potential. At high hydrocarbon-to-NO x ratios, however, all organics exhibited comparable O 3-forming potential.

  18. 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

  19. Development of a 1 D hydrodynamic habitat model for the Hippopotamus amphibious as basis for sustainable exploitation of hydroelectric power

    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

  20. Evaluation Of Sensitivity Of Mass-independent Oxygen Isotopes In Aerosol Nitrate To Environmental Factors Using A Photochemical Box Model

    NASA Astrophysics Data System (ADS)

    Dominguez, G.; Wilkins, G.; Jackson, T.; Brothers, L.; McCabe, J.; Thiemens, M. H.

    2007-12-01

    An existing photochemical box model for use in polluted marine boundary layers was modified to allow for the explicit tracking of the mass-independent isotopic composition of oxygen in aerosol nitrate as well as other atmospheric species such as OH and H2O2. This modified model was then used to study the sensitivity of the mass-independent isotopic composition of atmospheric nitrate(HNO3) to variables such as relative humidity, temperature ozone and NOx concentrations. Here we present the results of these studies and compare model predictions of the mass-independent oxygen isotopic composition of aerosol nitrate to measurements taken in fine (<1micron) and coarse (>1 micron) aerosol samples taken in a variety of locations, from coastal urban environments, the tropics (Ecuador), inland California (Riverside), and Antarctica. Regarding Antarctica, we comment on the isotopic composition of OH there and the ramifications of these findings for the isotopic composition of other oxygen bearing compounds in the Antarctic atmosphere.

  1. Photochemical Grid Modelling Study to Assess Potential Air Quality Impacts Associated with Energy Development in Colorado and Northern New Mexico.

    NASA Astrophysics Data System (ADS)

    Parker, L. K.; Morris, R. E.; Zapert, J.; Cook, F.; Koo, B.; Rasmussen, D.; Jung, J.; Grant, J.; Johnson, J.; Shah, T.; Pavlovic, T.

    2015-12-01

    The Colorado Air Resource Management Modeling Study (CARMMS) was funded by the Bureau of Land Management (BLM) to predict the impacts from future federal and non-federal energy development in Colorado and Northern New Mexico. The study used the Comprehensive Air Quality Model with extensions (CAMx) photochemical grid model (PGM) to quantify potential impacts from energy development from BLM field office planning areas. CAMx source apportionment technology was used to track the impacts from multiple (14) different emissions source regions (i.e. field office areas) within one simulation, as well as to assess the cumulative impact of emissions from all source regions combined. The energy development emissions estimates were for the year 2021 for three different development scenarios: (1) low; (2) high; (3) high with emissions mitigation. Impacts on air quality (AQ) including ozone, PM2.5, PM10, NO2, SO2, and air quality related values (AQRVs) such as atmospheric deposition, regional haze and changes in Acid Neutralizing Capacity (ANC) of lakes were quantified, and compared to establish threshold levels. In this presentation, we present a brief summary of the how the emission scenarios were developed, we compare the emission totals for each scenario, and then focus on the ozone impacts for each scenario to assess: (1). the difference in potential ozone impacts under the different development scenarios and (2). to establish the sensitivity of the ozone impacts to different emissions levels. Region-wide ozone impacts will be presented as well as impacts at specific locations with ozone monitors.

  2. Source identification and budget analysis on elevated levels of formaldehyde within ship plumes: a photochemical/dynamic model analysis

    NASA Astrophysics Data System (ADS)

    Song, C. H.; Kim, H. S.; von Glasow, R.; Brimblecombe, P.; Kim, J.; Park, R. J.; Woo, J. H.

    2010-06-01

    Elevated levels of formaldehyde (HCHO) along the ship corridors have been observed by satellite sensors, such as ESA/ERS-2 GOME (Global Ozone Monitoring Experiment), and were also predicted by global 3-D chemistry-transport models. In this study, three likely sources of the elevated HCHO levels were investigated to identify the detailed sources and examine the contributions of the sources (budget) of the elevated levels of HCHO in the ship corridors using a newly-developed ship-plume photochemical/dynamic model: (1) primary HCHO emission from ships; (2) secondary HCHO production via the atmospheric oxidation of Non-methane volatile organic compounds (NMVOCs) emitted from ships; and (3) atmospheric oxidation of CH4 within the ship plumes. From multiple ship-plume model simulations, CH4 oxidation by elevated levels of in-plume OH radicals was found to be the main factor responsible for the elevated levels of HCHO in the ship corridors. More than ~91% of the HCHO for the base ship plume case (ITCT 2K2 ship-plume case) is produced by this atmospheric chemical process, except in the areas close to the ship stacks where the main source of the elevated HCHO levels would be primary HCHO from the ships (due to the deactivation of CH4 oxidation from the depletion of in-plume OH radicals). Because of active CH4 oxidation (chemical destruction of CH4) by OH radicals, the instantaneous chemical lifetime of CH4 (τ CH4) decreased to ~0.45 yr inside the ship plume, which is in contrast to τ CH4 of ~1.1 yr in the background (up to ~41% decrease). A variety of likely ship-plume situations at three locations at different latitudes within the global ship corridors was also studied to determine the extent of the enhancements in the HCHOlevels in the marine boundary layer (MBL) influenced by ship emissions. It was found that the ship-plume HCHO levels could be 20.5-434.9 pptv higher than the background HCHO levels depending on the latitudinal locations of the ship plumes (i

  3. 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

  4. 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.

  5. Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy phenols from biomass burning

    NASA Astrophysics Data System (ADS)

    Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

    2014-03-01

    We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O : C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O : C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to depend on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O : C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

  6. Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy-phenols from biomass burning

    NASA Astrophysics Data System (ADS)

    Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

    2013-10-01

    We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy-phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O:C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O:C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to be dependent on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O:C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

  7. Photochemical grid model estimates of lateral boundary contributions to ozone and particulate matter across the continental United States

    NASA Astrophysics Data System (ADS)

    Baker, Kirk R.; Emery, Chris; Dolwick, Pat; Yarwood, Greg

    2015-12-01

    Multiple approaches to characterize lateral boundary contributions to photochemical model predicted ozone (O3) and particulate matter less than 2.5 microns in diameter (PM2.5) are available in the Comprehensive Air quality Model with extensions (CAMx). Here, three approaches are used for O3: (1) a comprehensive source apportionment scheme for chemical boundary conditions and emissions (OSAT), (2) chemically reactive tracers (RTRAC), and (3) chemically inert tracers. Two approaches are used for PM2.5: (1) particulate source apportionment (PSAT) and (2) chemically inert tracers. The inert tracer approach resulted in higher O3 lateral boundary contribution estimates because the method does not account for any O3 destruction reactions. OSAT and RTRAC estimate generally similar monthly average contributions during the warmer months although RTRAC estimates higher urban area contribution during the cold months because this RTRAC implementation did not treat O3 titration by NO. Accurate representation of lateral boundary O3 impacts must include appropriate accounting for O3 destruction reactions. OSAT and RTRAC were configured to estimate the contribution to modeled O3 from each of the four lateral faces of the model domain. RTRAC was configured to further stratify the western and northern boundaries by groups of vertical layers. The RTRAC approach showed that the largest O3 contributions to the continental U.S. are from the mid-troposphere, with less contribution from the upper troposphere/lower stratosphere. Inert tracers compared more closely to reactive tracers on average for PM2.5 compared to O3. This close agreement for PM2.5 indicates most of the lateral boundary contribution is from PM2.5 rather than precursor inflow. A strong relationship exists between model predicted PM2.5 boundary contribution and model overestimates of nitrate and organic carbon at IMPROVE monitor locations suggesting global model estimates of these species were overestimated at some places

  8. A mathematical model of non-photochemical quenching to study short-term light memory in plants.

    PubMed

    Matuszyńska, Anna; Heidari, Somayyeh; Jahns, Peter; Ebenhöh, Oliver

    2016-12-01

    Plants are permanently exposed to rapidly changing environments, therefore it is evident that they had to evolve mechanisms enabling them to dynamically adapt to such fluctuations. Here we study how plants can be trained to enhance their photoprotection and elaborate on the concept of the short-term illumination memory in Arabidopsis thaliana. By monitoring fluorescence emission dynamics we systematically observe the extent of non-photochemical quenching (NPQ) after previous light exposure to recognise and quantify the memory effect. We propose a simplified mathematical model of photosynthesis that includes the key components required for NPQ activation, which allows us to quantify the contribution to photoprotection by those components. Due to its reduced complexity, our model can be easily applied to study similar behavioural changes in other species, which we demonstrate by adapting it to the shadow-tolerant plant Epipremnum aureum. Our results indicate that a basic mechanism of short-term light memory is preserved. The slow component, accumulation of zeaxanthin, accounts for the amount of memory remaining after relaxation in darkness, while the fast one, antenna protonation, increases quenching efficiency. With our combined theoretical and experimental approach we provide a unifying framework describing common principles of key photoprotective mechanisms across species in general, mathematical terms.

  9. Numerical modeling of humic colloid borne americium (III) migration in column experiments using the transport/speciation code K1D and the KICAM model.

    PubMed

    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.

  10. Numerical modeling of humic colloid borne Americium (III) migration in column experiments using the transport/speciation code K1D and the KICAM model

    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.

  11. Application of Wavelet Filters in an Evaluation of Photochemical Model Performance

    EPA Science Inventory

    Air quality model evaluation can be enhanced with time-scale specific comparisons of outputs and observations. For example, high-frequency (hours to one day) time scale information in observed ozone is not well captured by deterministic models and its incorporation into model pe...

  12. Model-Based Least Squares Reconstruction of Coded Source Neutron Radiographs: Integrating the ORNL HFIR CG1D Source Model

    SciTech Connect

    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.

  13. OH-initiated heterogeneous oxidation of cholestane: a model system for understanding the photochemical aging of cyclic alkane aerosols.

    PubMed

    Zhang, Haofei; Ruehl, Christopher R; Chan, Arthur W H; Nah, Theodora; Worton, David R; Isaacman, Gabriel; Goldstein, Allen H; Wilson, Kevin R

    2013-11-27

    Aerosols containing aliphatic hydrocarbons play a substantial role in the urban atmosphere. Cyclic alkanes constitute a large fraction of aliphatic hydrocarbon emissions originating from incomplete combustion of diesel fuel and motor oil. In the present study, cholestane (C27H48) is used as a model system to examine the OH-initiated heterogeneous oxidation pathways of cyclic alkanes in a photochemical flow tube reactor. Oxidation products are collected on filters and analyzed by a novel soft ionization two-dimensional gas chromatography/mass spectrometry technique. The analysis reveals that the first-generation functionalization products (cholestanones, cholestanals, and cholestanols) are the dominant reaction products that account for up to 70% by mass of the total speciated compounds. The ratio of first-generation carbonyls to alcohols is near unity at every oxidation level. Among the cholestanones/cholestanals, 55% are found to have the carbonyl group on the rings of the androstane skeleton, while 74% of cholestanols have the hydroxyl group on the rings. Particle-phase oxidation products with carbon numbers less than 27 (i.e., "fragmentation products") and higher-generation functionalization products are much less abundant. Carbon bond cleavage was found to occur only on the side chain. Tertiary-carbon alkoxy radicals are suggested to play an important role in governing both the distribution of functionalization products (via alkoxy radical isomerization and reaction with oxygen) and the fragmentation products (via alkoxy radical decomposition). These results provide new insights into the oxidation mechanism of cyclic alkanes.

  14. A simple 1-D radiative-convective atmospheric model designed for integration into coupled models of magma ocean planets

    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.

  15. The Roles of RNA Polymerase I and III Subunits Polr1c and Polr1d in Craniofacial Development and in Zebrafish Models of Treacher Collins Syndrome

    PubMed Central

    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

  16. Mapping fractures using 1D anisotropic modelling of magnetotelluric data: a case study from the Otway Basin, Victoria, Australia

    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.

  17. Implementation and evaluation of PM2.5 source contribution analysis in a photochemical model

    EPA Science Inventory

    Source culpability assessments are useful for developing effective emissions control programs. The Integrated Source Apportionment Method (ISAM) has been implemented in the Community Multiscale Air Quality (CMAQ) model to track contributions from source groups and regions to ambi...

  18. Regional Scale Photochemical Model Evaluation of Total Mercury Wet Deposition and Speciated Ambient Mercury

    EPA Science Inventory

    Methylmercury is a known neurotoxin with deleterious health effects on humans and wildlife. Atmospheric deposition is the largest source of mercury loading to most terrestrial and aquatic ecosystems. Regional scale air quality models are needed to quantify mercury deposition resu...

  19. Interpretation of Lidar and Satellite Data Sets Using a Global Photochemical Model

    NASA Technical Reports Server (NTRS)

    Zenker, Thomas; Chyba, Thomas

    1999-01-01

    A primary goal of the NASA Tropospheric Chemistry Program (TCP) is to "contribute substantially to scientific understanding of human impacts on the global troposphere". In order to analyze global or regional trends and factors of the troposphere chemistry, for example, its oxidation capacity or composition, a continuous global/regional data coverage as well as model simulations are needed. The Global Tropospheric Experiment (GTE), a major component of the TCP, provides data vital to these questions via aircraft measurement of key trace chemical species in various remote regions of the world. Another component in NASA's effort are satellite projects for exploration of tropospheric chemistry and dynamics. A unique data product is the Tropospheric Ozone Residual (TOR) utilizing global tropospheric ozone data. Another key research tool are simulation studies of atmospheric chemistry and dynamics for the theoretical understanding of the atmosphere, the extrapolation of observed trends, and for sensitivity studies assessing a changing anthropogenic impact to air chemistry and climate. In the context with model simulations, field data derived from satellites or (airborne) field missions are needed for two purposes: 1. To initialize and validate model simulations, and 2., to interpret field data by comparison to model simulation results in order to analyze global or regional trends and deviations from standard tropospheric chemistry and transport conditions as defined by the simulations. Currently, there is neither a sufficient global data coverage available nor are existing well established global circulation models. The NASA LARC CTM model is currently not yet in a state to accomplish a sufficient tropospheric chemistry simulation, so that the current research under this cooperative agreement focuses on utilizing field data products for direct interpretation. They will be also available for model testing and a later interpretation with a finally utilized model.

  20. Analysis of observations and modeling of criteria pollutants and photochemical age indicators during MILAGRO at Tenango del Aire

    NASA Astrophysics Data System (ADS)

    Ruiz Suarez, L. G.

    2009-04-01

    We report measurements and modeling results from the mobile air quality monitoring unit and other instruments in Tenango del Aire (TA). Tenango del Aire is a small town in the mountain pass between the Siera de Chichinautzin and the Popocatepel and Iztachiuatl Volcanos. The pass joins the Valley of Mexico and the Valley of Cuernavaca. TA was the most shouter and equipped site on that flank of MILAGRO. We compare model results and measurements of O3, NOx, NOy, CO, SO2, CH2O, mixing high and some VOC speciated analysis. Indicators of photochemical age as O3/CO, NOy/CO, are also reported. Mean hourly averages for all the campaign are reported. Specific episodes are also analyzed in depth. Evidence of a polluted regional background atmosphere is shown. The basic average surface transport patern was as follows, from 09:00 to 12:00 winds from the north arrive to TA bringing fresh polluted parcels from the highly populated sowtheast parts of the MCMA. Between 12:00 and 13:00 hours a shift of wind direction brings back those or parts of those parcels and parcels farer away. Most of the times, this conditions continues until next morning when for few hours air again drains south from the valley of Mexico. Ozone reaches a maximum value between 12:00 and 13:00, and these values stay still until after 18:00. Average value of this plateau is 80 ppb. During this plateau indicators as O3/CO and NOy/CO show that air parcels passing over TA are photochemicaly aged.

  1. Atmospheric Photochemical Modeling of Turbine Engine Fuels. Phase I. Experimental Studies. Volume 1. Results and Discussion.

    DTIC Science & Technology

    1984-09-01

    methylglyoxal and (from 71 i0 o-xylene) biacetyl (References 34-37), though recent modeling studies indicate that formation of additional, as yet...cannot form methylglyoxal , which is believed to be the major radical source in NOx-air photooxidations of toluene and the xylenes (Ref- erences 12

  2. Utilization of UARS Data in Validation of Photochemical and Dynamical Mechanism in Stratospheric Models

    NASA Technical Reports Server (NTRS)

    Rodriquez, Jose M.; Hu, Wenjie; Ko, Malcolm K.W.

    1996-01-01

    The global three-dimensional measurement of long- and short-lived species from Upper Atmospheric Research Satellite (UARS) provides a unique opportunity to validate chemistry and dynamics mechanisms in the middle atmosphere. During the past three months, we focused on expanding our study of data-model comparisons to whole time periods when Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument were operating.

  3. PHOTOCHEMICAL SIMULATIONS OF POINT SOURCE EMISSIONS WITH THE MODELS-3 CMAQ PLUME-IN-GRID APPROACH

    EPA Science Inventory

    A plume-in-grid (PinG) approach has been designed to provide a realistic treatment for the simulation the dynamic and chemical processes impacting pollutant species in major point source plumes during a subgrid scale phase within an Eulerian grid modeling framework. The PinG sci...

  4. SIMULATIONS OF AEROSOLS AND PHOTOCHEMICAL SPECIES WITH THE CMAQ PLUME-IN-GRID MODELING SYSTEM

    EPA Science Inventory

    A plume-in-grid (PinG) method has been an integral component of the CMAQ modeling system and has been designed in order to realistically simulate the relevant processes impacting pollutant concentrations in plumes released from major point sources. In particular, considerable di...

  5. ESTIMATING TRANSPORT AND DEPOSITION OF A SEMI-VOLATILE COMPOUND WITH A REGIONAL PHOTOCHEMICAL MODEL

    EPA Science Inventory

    To simulate the fate of compounds that are considered semi-volatile and toxic, we have modified a model for regional particulate matter. Our changes introduce a semi-volatile compound into the atmosphere as gaseous emissions from an area source. Once emitted, the gas can transf...

  6. Photochemical modeling of the Ozark isoprene volcano: MEGAN, BEIS, and their impacts on air quality predictions.

    PubMed

    Carlton, Annmarie G; Baker, Kirk R

    2011-05-15

    Biogenic volatile organic compounds (BVOCs) contribute substantially to atmospheric carbon, exerting influence on air quality and climate. Two widely used models, the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the Biogenic Emission Inventory System (BEIS) are employed to generate emissions for application in the CMAQ air quality model. Predictions of isoprene, monoterpenes, ozone, formaldehyde, and secondary organic carbon (SOC) are compared to surface and aloft measurements made during an intensive study in the Ozarks, a large isoprene emitting region. MEGAN and BEIS predict spatially similar emissions but magnitudes differ. The total VOC reactivity of the emissions, as developed for the CB05 gas-phase chemical mechanism, is a factor of 2 different between the models. Isoprene estimates by CMAQ-MEGAN are higher and more variable than surface and aloft measurements, whereas CMAQ-BEIS predictions are lower. CMAQ ozone predictions are similar and compare well with measurements using either MEGAN or BEIS. However, CMAQ-MEGAN overpredicts formaldehyde. CMAQ-BEIS SOC predictions are lower than observational estimates for every sample. CMAQ-MEGAN underpredicts SOC ∼ 80% of the time, despite overprediction of precursor VOCs. CMAQ-MEGAN isoprene predictions improve when prognostically predicted solar radiation is replaced with the GEWEX satellite product. CMAQ-BEIS does not exhibit similar photosensitivity.

  7. Seasonal versus Episodic Performance Evaluation for an Eulerian Photochemical Air Quality Model

    SciTech Connect

    Jin, Ling; Brown, Nancy J.; Harley, Robert A.; Bao, Jian-Wen; Michelson, Sara A; Wilczak, James M

    2010-04-16

    This study presents detailed evaluation of the seasonal and episodic performance of the Community Multiscale Air Quality (CMAQ) modeling system applied to simulate air quality at a fine grid spacing (4 km horizontal resolution) in central California, where ozone air pollution problems are severe. A rich aerometric database collected during the summer 2000 Central California Ozone Study (CCOS) is used to prepare model inputs and to evaluate meteorological simulations and chemical outputs. We examine both temporal and spatial behaviors of ozone predictions. We highlight synoptically driven high-ozone events (exemplified by the four intensive operating periods (IOPs)) for evaluating both meteorological inputs and chemical outputs (ozone and its precursors) and compare them to the summer average. For most of the summer days, cross-domain normalized gross errors are less than 25% for modeled hourly ozone, and normalized biases are between {+-}15% for both hourly and peak (1 h and 8 h) ozone. The domain-wide aggregated metrics indicate similar performance between the IOPs and the whole summer with respect to predicted ozone and its precursors. Episode-to-episode differences in ozone predictions are more pronounced at a subregional level. The model performs consistently better in the San Joaquin Valley than other air basins, and episodic ozone predictions there are similar to the summer average. Poorer model performance (normalized peak ozone biases <-15% or >15%) is found in the Sacramento Valley and the Bay Area and is most noticeable in episodes that are subject to the largest uncertainties in meteorological fields (wind directions in the Sacramento Valley and timing and strength of onshore flow in the Bay Area) within the boundary layer.

  8. Photochemical transformation of phenylurea herbicides in surface waters: a model assessment of persistence, and implications for the possible generation of hazardous intermediates.

    PubMed

    Fabbri, Debora; Minella, Marco; Maurino, Valter; Minero, Claudio; Vione, Davide

    2015-01-01

    This work models the phototransformation kinetics in surface waters of five phenylurea herbicides (diuron, fenuron, isoproturon, metoxuron and chlortoluron), for which important photochemical parameters are available in the literature (direct photolysis quantum yields and reaction rate constants with ·OH, CO3(-·) and the triplet states of chromophoric dissolved organic matter, (3)CDOM*). Model calculations suggest that isoproturon and metoxuron would be the least photochemically persistent and diuron the most persistent compound. Reactions with ·OH and (3)CDOM* would be the main phototransformation pathways for all compounds in the majority of environmental conditions. Reaction with CO3(-) could be important in waters with low dissolved organic carbon (DOC), while direct photolysis would be negligible for fenuron, quite important for chlortoluron, and somewhat significant for the other compounds. The direct photolysis of metoxuron and diuron is known to increase toxicity, and such a photoreaction pathway would be enhanced at intermediate DOC values (1-4 mg C L(1)). The reaction between phenylureas and ·OH is known to produce toxic intermediates, differently from (3)CDOM*. Therefore, the shift of reactivity from ·OH to (3)CDOM* with increasing DOC could reduce the environmental impact of photochemical transformation.

  9. THE DUST PROPERTIES OF z {approx} 3 MIPS-LBGs FROM PHOTOCHEMICAL MODELS

    SciTech Connect

    Fan, X. L.; Pipino, A.; Matteucci, F.

    2013-05-10

    The stacked spectral energy distribution (SED) 24 {mu}m Lyman break galaxies (MIPS-LBGs) detected by the Multiband Imaging Photometer for Spitzer (MIPS) is fitted by means of the spectrophotometric model GRASIL with an ''educated'' fitting approach which benefits from the results of chemical evolution models. The star formation rate-age-metallicity degeneracies of SED modeling are broken by using star formation history (SFH) and chemical enrichment history suggested by chemical models. The dust mass, dust abundance, and chemical pattern of elements locked in the dust component are also directly provided by chemical models. Using our new ''fitting'' approach, we derive the total mass M{sub tot}, stellar mass M{sub *}, gas mass M{sub g} , dust mass M{sub d} , age, and star formation rate (SFR) of the stacked MIPS-LBG in a self-consistent way. Our estimate of M{sub *} = 8 Multiplication-Sign 10{sup 10} of the stacked MIPS-LBG agrees with other works based on UV-optical SED fitting. We suggest that the MIPS-LBGs at z {approx} 3 are young (0.3-0.6 Gyr), massive (M{sub tot} {approx} 10{sup 11} M{sub Sun }), dusty (M{sub d} {approx} 10{sup 8} M{sub Sun }), and metal-rich (Z {approx} Z{sub Sun }) progenitors of elliptical galaxies undergoing a strong burst of star formation (SFR {approx} 200 M{sub Sun} yr{sup -1}). Our estimate of M{sub d} = 7 Multiplication-Sign 10{sup 7} M{sub Sun} of the stacked MIPS-LBG is about a factor of eight lower than the estimated value based on single temperature graybody fitting, suggesting that self-consistent SED models are needed to estimate dust mass. By comparing with Milky Way molecular cloud and dust properties, we suggest that denser and dustier environments and flatter dust size distribution are likely in high-redshift massive star-forming galaxies. These dust properties, as well as the different types of SFHs, can cause different SED shapes between high-redshift star-forming ellipticals and local starburst templates. This discrepancy

  10. Photochemical Modeling at Santiago, Chile (33.5° S, 70.6° W)

    NASA Astrophysics Data System (ADS)

    Jorquera, H.; Castro, J.

    2007-12-01

    The greater metropolitan region of Santiago, Chile (6.5 million inhabitants) is located in a basin with complex topography that promotes pollutant trapping below the subsidence-based thermal inversion. The (diurnal) upwind land use consists of agriculture activities that contribute to the emissions of the city itself. Santiago is the 7th Latin American city in population, and 40% of the country's inhabitants live there. Steady economic growth in the last 20 years has resulted in a fast increment of car ownership, industrial activity, fuel consumption, etc. As a result of air quality regulations, ambient PM10 and PM2.5 concentrations have been reduced significantly between 1990 and 2000. However, ozone ambient concentrations do not show a downward trend, and the 98th percentile of the 8-h moving average consistently exceeds the 120 (μg/m3) standard. Also, the current annual ambient PM2.5 concentration is near 30 (μg/m3), twice the US standard. We have developed an emissions inventory for the greater metropolitan region of Santiago (base year 2005), including agriculture and biogenic emissions at the regional scale. We use the MM5 mesoscale modeling system coupled with the CAMx air quality model to: a) assess the quality of the emission inventory database, b) improve emission estimates by means of inverse modeling, c) model ozone formation and transport, with an emphasis on estimating ozone sensitivities with respect to different geographical regions and emission sources. We do this analysis for two multi-day episodes in spring and summer seasons. Results of constraining CO, VOC, NOx and primary PM emissions with ambient monitoring data using a Kalman filter approach will be shown, along with the results for the ozone sensitivity estimates.

  11. 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).

  12. Photochemical Pollution Modeling of Ozone at Metropolitan Area of Porto Alegre - RS/Brazil using WRF/Chem

    NASA Astrophysics Data System (ADS)

    Cuchiara, G. C.; Carvalho, J.

    2013-05-01

    One of the main problems related to air pollution in urban areas is caused by photochemical oxidants, particularly troposphere ozone (O3), which is considered a harmful substance. The O3 precursors (carbon monoxide CO, nitrogen oxides NOx and hydrocarbons HCs) are predominantly of anthropogenic origin in these areas, and vehicles are the main emission sources. Due to the increased urbanization and industrial development in recent decades, air pollutant emissions have increased likewise, mainly by mobile sources in the highly urbanized and developed areas, such as the Metropolitan Area of Porto Alegre-RS (MAPA). According to legal regulations implemented in Brazil in 2005, which aimed at increasing the fraction of biofuels in the national energy matrix, 2% biodiesel were supposed to be added to the fuel mixture within three years, and up to 5% after eight years of implementation of these regulations. Our work performs an analysis of surface concentrations for O3, NOx, CO, and HCs through numerical simulations with WRF/Chem (Weather Research and Forecasting model with Chemistry). The model is validated against observational data obtained from the local urban air quality network for the period from January 5 to 9, 2009 (96 hours). One part of the study focused on the comparison of simulated meteorological variables, to observational data from two stations in MAPA. The results showed that the model simulates well the diurnal evolution of pressure and temperature at the surface, but is much less accurate for wind speed. Another part included the evaluation of model results of WRF/Chem for O3 versus observed data at air quality stations Esteio and Porto Alegre. Comparisons between simulated and observed O3 revealed that the model simulates well the evolution of the observed values, but on many occasions the model did not reproduce well the maximum and minimum concentrations. Finally, a preliminary quantitative sensitivity study on the impact of biofuel on the

  13. An artificial muscle model unit based on inorganic nanosheet sliding by photochemical reaction.

    PubMed

    Nabetani, Yu; Takamura, Hazuki; Hayasaka, Yuika; Sasamoto, Shin; Tanamura, Yoshihiko; Shimada, Tetsuya; Masui, Dai; Takagi, Shinsuke; Tachibana, Hiroshi; Tong, Zhiwei; Inoue, Haruo

    2013-04-21

    From the viewpoint of developing photoresponsive supramolecular systems in microenvironments to exhibit more sophisticated photo-functions even at the macroscopic level, inorganic/organic hybrid compounds based on clay or niobate nanosheets as the microenvironments were prepared, characterized, and examined for their photoreactions. We show here a novel type of artificial muscle model unit having much similarity with that in natural muscle fibrils. Upon photoirradiation, the organic/inorganic hybrid nanosheets reversibly slide horizontally on a giant scale, and the interlayer spaces in the layered hybrid structure shrink and expand vertically. In particular, our layered hybrid molecular system exhibits a macroscopic morphological change on a giant scale (~1500 nm) compared with the molecular size of ~1 nm, based on a reversible sliding mechanism.

  14. Photochemically induced spinal ischaemia: a model of spinal cord trauma in the rat

    NASA Astrophysics Data System (ADS)

    Olby, Natasha J.; Blakemore, W. F.

    1995-05-01

    Focal thrombosis was induced in the dorsal funiculus of the rat spinal cord by exposing the cord to light following intravenous injection of the photoactive dye, rose bengal. The light source was a 599 standing wave dye laser, pumped by an Innova 70 - 4 argon ion laser (Coherent Ltd, Cambridge, UK) and the light was delivered to the operative site via an optical fiber. The histological characteristics of the development and resolution of the lesion have been studied. Forty rats were examined with light and electron microscopy at various time points between 30 minutes and one month after irradiation and the lesion length was measured. Platelet aggregation, increased extracellular space in the white matter and vacuolation of the neurones and glia of the grey matter were present 30 minutes after injury. Progressive necrosis of the white and grey matter developed over the subsequent 24 hours to produce a fusiform lesion that occupied the dorsal funiculus and dorsal horns of the spinal cord at its center and tapered cranially and caudally along the dorsal columns for a total distance of seven millimeters. By one month after injury the area of necrosis had become a cyst lined by astrocytes ventrolaterally and meningeal cells dorsally. Measurements of lesion length showed a variability of 26%. This model of spinal cord trauma produces a lesion that is sufficiently reproducible to be suitable for performing studies aimed at tissue preservation and repair.

  15. Validating a 0D predator-prey model for LH Transition with its 1D-2D supersets: effects of heating and fueling on Hysteresis and transition dynamics

    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.

  16. Characterizing the unique photochemical environment in China

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Wang, Y.; Gu, D.; Zhao, C.; Huey, L. G.; Stickel, R.; Liao, J.

    2010-12-01

    Recent observational evidence suggests that the atmospheric chemical system over China could be more complex than expected, possibly as a result of the rapid increasing anthropogenic emissions. During the CAREBeijing-2007 Experiment in August of 2007, up to 14 ppbv of peroxyacetyl nitrate (PAN, CH3C(O)OONO2) and 4.5 ppbv of glyoxal (CHOCHO) were observed, among the highest levels observed in the world in recent years. Elevated nitrous acid (HNO2) (~1.0 ppbv on average) was also observed in the early afternoon despite of the moderate amount of its precursors, i.e. nitrogen oxides (NOx=NO + NO2). We employ a 1-D photochemical model (REAM) to analyze the observations. The results indicate that reactive aromatics are the dominating source of PAN (55%-75%) and glyoxal (90%), and methylglyoxal is the major precursor of peroxy acetyl radical (50%). Downward transport from boundary layer is found to contribute ~50% of the PAN observed at surface. Photolysis of HNO2 is by far the largest primary OH source (more than 50%) throughout the daytime, and yet the fast formation rate of HNO2 inferred from the observations could not be explained by current known mechanisms. Detailed photochemical analysis is conducted to understand the controlling factors for O3 formation. O3 formation chemistry is strongly affected by aromatics and HNO2. By providing a large primary OH source, HNO2 leads to ~25% enhancement of the average O3 production rate, and aromatics contribute ~40% by serving as a major source of RO2 and HO2 radicals. Due to the large abundance of reactive hydrocarbons, O3 formation is generally NOx limited, although the sensitivity is low that a 50% reduction of NOx could only result in less than 25% reduction of the O3 production rate. Future research targeting HNO2 formation mechanism and emission sources of aromatics is necessary for better understanding the unique photochemical environment in China under significant anthropogenic impacts and the regional pollution

  17. Gender-Specific Hippocampal Dysrhythmia and Aberrant Hippocampal and Cortical Excitability in the APPswePS1dE9 Model of Alzheimer's Disease

    PubMed Central

    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

  18. Photochemical smog modeling for assessment of potential impacts of different management strategies on air quality of the Bangkok Metropolitan Region, Thailand.

    PubMed

    Oanh, Nguyen Thi Kim; Zhang, Baoning

    2004-10-01

    A photochemical smog model system, the Variable-Grid Urban Airshed Model/Systems Applications International Mesoscale Model (UAM-V/SAIMM), was used to investigate photochemical pollution in the Bangkok Metropolitan Region (BMR). The model system was first applied to simulate a historical photochemical smog episode of two days (January 13-14, 1997) using the 1997 anthropogenic emission database available at the Pollution Control Department and an estimated biogenic emission. The output 1-hr ozone (O3) for BMR, however, did not meet the U.S. Environmental Protection Agency suggested performance criteria. The simulated minimum and maximum O3 values in the domain were much higher than the observations. Multiple model runs with different precursor emission reduction scenarios showed that the best model performance with the simulated 1-hr O3 meeting all the criteria was obtained when the volatile organic compound (VOC) and oxides of nitrogen (NOx) emission from mobile source reduced by 50% and carbon monoxide by 20% from the original database. Various combinations of anthropogenic and biogenic emissions in Bangkok and surrounding provinces were simulated to assess the contribution of different sources to O3 pollution in the city. O3 formation in Bangkok was found to be more VOC-sensitive than NOx-sensitive. To attain the Thailand ambient air quality standard for 1-hr O3 of 100 ppb, VOC emission in BMR should be reduced by 50-60%. Management strategies considered in the scenario study consist of Stage I, Stage II vapor control, replacement of two-stroke by four-stroke motorcycles, 100% compressed natural gas bus, 100% natural gas-fired power plants, and replacement of methyltertiarybutylether by ethanol as an additive for gasoline.

  19. Ice Concentration Retrieval in Stratiform Mixed-phase Clouds Using Cloud Radar Reflectivity Measurements and 1D Ice Growth Model Simulations

    SciTech Connect

    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.

  20. Near-infrared spectro-interferometry of Mira variables and comparisons to 1D dynamic model atmospheres and 3D convection simulations

    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

  1. The photochemical smog pollution in Beijing

    SciTech Connect

    Xiaoyan Tang

    1996-12-31

    The photochemical smog pollution in summer time has been studied in Beijing area. The systematic field measurements associated with meteorological observation was conducted in 1986, 1987 and 1993. The spatial and temporal distribution of O{sub 3} and specific formation condition of photochemical smog, including vehicle emission sources and meteorological factors etc. in summer were studied and discussed. The prediction of O{sub 3} ambient air concentration in Beijing area in 2000, 2005 and 2010 by model simulation were also discussed.

  2. 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.

  3. A new time-dependent analytic model for radiation-induced photocurrent in finite 1D epitaxial diodes.

    SciTech Connect

    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].

  4. Pulse wave propagation in a model human arterial network: Assessment of 1-D visco-elastic simulations against in vitro measurements

    PubMed Central

    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

  5. Coupling WEPP and 3ST1D models for improved prediction of flow and sediment transport at watershed scales

    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...

  6. 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.

  7. Differences in Water Vapor Radiative Transfer among 1D Models Can Significantly Affect the Inner Edge of the Habitable Zone

    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.

  8. Status of the solar and infrared radiation submodels in the LLNL 1-D and 2-D chemical-transport models

    SciTech Connect

    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.

  9. Coupling 1D Navier Stokes equation with autoregulation lumped parameter networks for accurate cerebral blood flow modeling

    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.

  10. Using an improved 1D boundary layer model with CFD for flux prediction in gas-sparged tubular membrane ultrafiltration.

    PubMed

    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.

  11. The impact of soil moisture on the spin up of 1-D Noah land surface model at a site in monsoonal region

    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.

  12. Establishing the Capability of a 1D SVAT Modelling Scheme in Predicting Key Biophysical Vegetation Characterisation Parameters

    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

  13. 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.

  14. Improved Large-Scale Inundation Modelling by 1D-2D Coupling and Consideration of Hydrologic and Hydrodynamic Processes - a Case Study in the Amazon

    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

  15. Non-thermal O/1D/ produced by dissociative recombination of O2/+/ - A theoretical model and observational results. [in earth atmosphere

    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.

  16. Can a partially molten metasedimentary sequence convect? Insights from the El Oro Complex (Ecuador) and 1D thermal modelling.

    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).

  17. Integrating models to simulate emergent behaviour: effects of organic matter on soil hydraulics in the ICZ-1D soil-vegetation model

    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.

  18. 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.

  19. 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).

  20. The 1D parabolic-parabolic Patlak-Keller-Segel model of chemotaxis: The particular integrable case and soliton solution

    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.

  1. Coastal fog prediction with a coupled model (1D+3D) system using the data from a 300 m met tower as input

    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.

  2. Evaluation of Bulk Charging in Geostationary Transfer Orbit and Earth Escape Trajectories Using the Numit 1-D Charging Model

    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.

  3. 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.

  4. Transient runoff-runon model for a 1-D slope with random infiltrability: flow statistics and connectivity

    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.

  5. A model assessment of the ability of lake water in Terra Nova Bay, Antarctica, to induce the photochemical degradation of emerging contaminants.

    PubMed

    Minella, Marco; Maurino, Valter; Minero, Claudio; Vione, Davide

    2016-11-01

    The shallow lakes located in Terra Nova Bay, Antarctica, are free from ice for only up to a couple of months (mid December to early/mid February) during the austral summer. In the rest of the year, the ice cover shields the light and inhibits the photochemical processes in the water columns. Previous work has shown that chromophoric dissolved organic matter (CDOM) in these lakes is very reactive photochemically. A model assessment is here provided of lake-water photoreactivity in field conditions, based on experimental data of lake water absorption spectra, chemistry and photochemistry obtained previously, taking into account the water depth and the irradiation conditions of the Antarctic summer. The chosen sample contaminants were the solar filter benzophenone-3 and the antimicrobial agent triclosan, which have very well known photoreactivity and have been found in a variety of environmental matrices in the Antarctic continent. The two compounds would have a half-life time of just a few days or less in the lake water during the Antarctic summertime, largely due to reaction with CDOM triplet states ((3)CDOM*). In general, pollutants that occur in the ice and could be released to lake water upon ice melting (around or soon after the December solstice) would be quickly photodegraded if they undergo fast reaction with (3)CDOM*. With some compounds, the important (3)CDOM* reactions might favour the production of harmful secondary pollutants, such as 2,8-dichlorodibenzodioxin from the basic (anionic) form of triclosan.

  6. 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.

  7. Air Quality Model Evaluation International Initiative (AQMEII): Advancing State of the Science in Regional Photochemical Modeling and Its Applications

    EPA Science Inventory

    Although the focus in the 1970s was primarily on urban air pollution models, it is well known that pollution problems such as acid rain, ozone, and fine particulate matter are regional in scope, requiring regional-scale multipollutant models. In North America and Europe, several ...

  8. RESULTS OF PHOTOCHEMICAL SIMULATIONS OF SUBGRID SCALE POINT SOURCE EMISSIONS WITH THE MODELS-3 CMAQ MODELING SYSTEM

    EPA Science Inventory

    The Community Multiscale Air Quality (CMAQ) / Plume-in-Grid (PinG) model was applied on a domain encompassing the greater Nashville, Tennessee region. Model simulations were performed for selected days in July 1995 during the Southern Oxidant Study (SOS) field study program wh...

  9. Dimuon radiation at relativistic energies available at the CERN Super Proton Synchrotron within a (3 + 1)D hydrodynamic + cascade model

    SciTech Connect

    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

  10. Photochemical tissue bonding

    DOEpatents

    Redmond, Robert W [Brookline, MA; Kochevar, Irene E [Charlestown, MA

    2012-01-10

    Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

  11. Basin infilling of a schematic 1D estuary using two different approaches: an aggregate diffusive type model and a processed based model.

    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

  12. Mitochondrial dynamics changes with age in an APPsw/PS1dE9 mouse model of Alzheimer’s disease

    PubMed Central

    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

  13. A comparison of 1D analytical model and 3D finite element analysis with experiments for a rosen-type piezoelectric transformer.

    PubMed

    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.

  14. Comparison of ground-based UV irradiance measurements with satellite-derived values and 1-D- and 3-D-radiative transfer model calculations in mountainous terrain

    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

  15. The LAPS Project : A live 1D Radiative-Convective Model to explore the possible climates of terrestrial planets and exoplanets.

    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/ .

  16. Simulation of decay heat removal by natural convection in a pool type fast reactor model-ramona-with coupled 1D/2D thermal hydraulic code system

    SciTech Connect

    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.

  17. EMODEL_1D v. 1.0

    SciTech Connect

    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.

  18. Study using a three-dimensional photochemical smog formation model under conditions of complex flow: Application of the Urban Airshed Model to the Tokyo Metropolitan Area. Rept. for Jan 85-Jan 91

    SciTech Connect

    Wakamatsu, S.; Schere, K.L.

    1991-03-01

    The purpose of the study is to evaluate the Urban Airshed Model (UAM), a three-dimensional photochemical urban air quality simulation model, using field observations from the Tokyo Metropolitan Area. Emphasis was placed on the photochemical smog formation mechanism under stagnant meteorological conditions. The UAM produced reasonable calculated results for the diurnal, areal and vertical distributions of O3 concentrations covering the Tokyo Metropolitan Area. The role and significance of the previous day's secondary pollutants on O3 formation mechanisms were also investigated. During the night time, high values of secondary pollutant concentrations were predicted above the radiation inversion layer. These aged pollutants were then entrained into the mixing layer during the day in accordance with the elevation of the lid. These characteristic features were also observed in the field study.

  19. Bridging the gap between global models and full fluid models: a fast 1D semi-analytical fluid model for electronegative plasmas

    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.

  20. Photochemical isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1987-01-01

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  1. Stratospheric Ozone: Transport, Photochemical Production and Loss

    NASA Technical Reports Server (NTRS)

    Douglass, A. R.; Kawa, S. R.; Jackman, C. H.

    2003-01-01

    Observations from various satellite instruments (e.g., Total Ozone Mapping Spectrometer (TOMS), Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS)) specify the latitude and seasonal variations of total ozone and ozone as a function of altitude. These seasonal variations change with latitude and altitude partly due to seasonal variation in transport and temperature, partly due to differences in the balance between photochemical production and loss processes, and partly due to differences in the relative importance of the various ozone loss processes. Comparisons of modeled seasonal ozone behavior with observations test the following: the seasonal dependence of dynamical processes where these dominate the ozone tendency; the seasonal dependence of photochemical processes in the upper stratosphere; and the seasonal change in the balance between photochemical and dynamical processes.

  2. Impacts of Leads on the Wintertime Sea-ice Environment Using 1D and 3D Models Validated with In-Situ Observations

    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

  3. Assessing the sensitivity of the hydroxyl radical to model biases in composition and temperature using a single-column photochemical model for Lauder, New Zealand

    NASA Astrophysics Data System (ADS)

    López-Comí, Laura; Morgenstern, Olaf; Zeng, Guang; Masters, Sarah L.; Querel, Richard R.; Nedoluha, Gerald E.

    2016-11-01

    We assess the major factors contributing to local biases in the hydroxyl radical (OH) as simulated by a global chemistry-climate model, using a single-column photochemical model (SCM) analysis. The SCM has been constructed to represent atmospheric chemistry at Lauder, New Zealand, which is representative of the background atmosphere of the Southern Hemisphere (SH) mid-latitudes. We use long-term observations of variables essential to tropospheric OH chemistry, i.e. ozone (O3), water vapour (H2O), methane (CH4), carbon monoxide (CO), and temperature, and assess how using these measurements affect OH calculated in the SCM, relative to a reference simulation only using modelled fields. The analysis spans 1994 to 2010. Results show that OH responds approximately linearly to correcting biases in O3, H2O, CO, CH4, and temperature. The biggest impact on OH is due to correcting an overestimation by approximately 20 to 60 % of H2O, using radiosonde observations. Correcting this moist bias leads to a reduction of OH by around 5 to 35 %. This is followed by correcting predominantly overestimated O3. In the troposphere, the model biases are mostly in the range of -10 to 30 %. The impact of changing O3 on OH is due to two pathways; the OH responses to both are of similar magnitude but different seasonality: correcting in situ tropospheric ozone leads to changes in OH in the range -14 to 4 %, whereas correcting the photolysis rate of O3 in accordance with overhead column ozone changes leads to increases of OH of 8 to 16 %. The OH sensitivities to correcting CH4, CO, and temperature biases are all minor effects. The work demonstrates the feasibility of quantitatively assessing OH sensitivity to biases in longer-lived species, which can help explain differences in simulated OH between global chemistry models and relative to observations. In addition to clear-sky simulations, we have performed idealized sensitivity simulations to assess the impact of clouds

  4. Modeling Large Water Infiltration Events in Small Plots Using the 1-D Finite Water-content Method and Numerical Solutions to the Richards' Equation.

    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

  5. Effect of the band structure in a rigorous two-body model with long-range interactions in 1D optical lattices

    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).

  6. Perinatal Choline Supplementation Reduces Amyloidosis and Increases Choline Acetyltransferase Expression in the Hippocampus of the APPswePS1dE9 Alzheimer's Disease Model Mice

    PubMed Central

    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

  7. Recent Advances in the Modeling of the Transport of Two-Plasmon-Decay Electrons in the 1-D Hydrodynamic Code LILAC

    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.

  8. Fast Photochemical Oxidation of Proteins (FPOP) for Comparing Structures of Protein/Ligand Complexes: The Calmodulin-peptide Model System

    PubMed Central

    Zhang, Hao; Gau, Brian C.; Jones, Lisa M.; Vidavsky, Ilan; Gross, Michael L.

    2010-01-01

    Fast Photochemical Oxidation of Proteins (FPOP) is a mass-spectrometry-based protein footprinting method that modifies proteins on the microsecond time scale. Highly reactive •OH, produced by laser photolysis of hydrogen peroxide, oxidatively modifies the side chains of approximately one half the common amino acids on this time scale. Owing to the short labeling exposure, only solvent-accessible residues are sampled. Quantification of the modification extent for the apo and holo states of a protein-ligand complex should provide structurally sensitive information at the amino-acid level to compare the structures of unknown protein complexes with known ones. We report here the use of FPOP to monitor the structural changes of calmodulin in its established binding to M13 of the skeletal muscle myosin light chain kinase. We use the outcome to establish the unknown structures resulting from binding with melittin and mastoparan. The structural comparison follows from a comprehensive examination of the extent of FPOP modifications as measured by proteolysis and LC-MS/MS for each protein-ligand equilibrium. The results not only show that the three calmodulin-peptide complexes have similar structures but also reveal those regions of the protein that became more or less solvent-accessible upon binding. This approach has the potential for relatively high throughput, information-dense characterization of a series of protein-ligand complexes in biochemistry and drug discovery when the structure of one reference complex is known, as is the case for calmodulin and M13 of the skeletal muscle myosin light chain kinase, and the structures of related complexes are not,. PMID:21142124

  9. Evaluation of emission control strategies to reduce ozone pollution in the Paso del Norte region using a photochemical air quality modeling system

    NASA Astrophysics Data System (ADS)

    Valenzuela, Victor Hugo

    Air pollution emissions control strategies to reduce ozone precursor pollutants are analyzed by applying a photochemical modeling system. Simulations of air quality conditions during an ozone episode which occurred in June, 2006 are undertaken by increasing or reducing area source emissions in Ciudad Juarez, Chihuahua, Mexico. Two air pollutants are primary drivers in the formation of tropospheric ozone. Oxides of nitrogen (NOx) and volatile organic compounds (VOC) undergo multiple chemical reactions under favorable meteorological conditions to form ozone, which is a secondary pollutant that irritates respiratory systems in sensitive individuals especially the elderly and young children. The U.S. Environmental Protection Agency established National Ambient Air Quality Standards (NAAQS) to limit ambient air pollutants such as ozone by establishing an 8-hour average concentration of 0.075 ppm as the threshold at which a violation of the standard occurs. Ozone forms primarily due reactions in the troposphere of NOx and VOC emissions generated primarily by anthropogenic sources in urban regions. Data from emissions inventories indicate area sources account for ˜15 of NOx and ˜45% of regional VOC emissions. Area sources include gasoline stations, automotive paint bodyshops and nonroad mobile sources. Multiplicity of air pollution emissions sources provides an opportunity to investigate and potentially implement air quality improvement strategies to reduce emissions which contribute to elevated ozone concentrations. A baseline modeling scenario was established using the CAMx photochemical air quality model from which a series of sensitivity analyses for evaluating air quality control strategies were conducted. Modifications to area source emissions were made by varying NOx and / or VOC emissions in the areas of particular interest. Model performance was assessed for each sensitivity analysis. Normalized bias (NB) and normalized error (NE) were used to identify

  10. An original approach combining aircraft observations and 1D modelling to quantify the role of deep convection on formaldehyde in tropical UT

    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

  11. Isoprene: a photochemical kinetic mechanism

    SciTech Connect

    Killus, J.P.; Whitten, G.Z.

    1984-03-01

    A computer-modeling study has produced a photochemical kinetic mechanism for the atmospheric chemistry of isoprene, a naturally occurring common constituent of the troposphere. The kinetic mechnism is ready for use in atmospheric models because the reactions described are shown to adequately reproduce the results of a series of outdoor smog chamber experiments which encompass a wide range of precursor conditions of isoprene and NO/sub x/. Isoprene is a very reactive molecule that can contribute as much as 50% of the overall reactivity of rural air even though isoprene might be only 6% of the ambient hydrocarbon level. The major intermediate products of the atmospheric oxidation of isoprene, methyl vinyl ketone, methacrolein, methylglyoxal, and formaldehyde are also highly reactive. 25 references.

  12. Photochemical cutting of fabrics

    DOEpatents

    Piltch, Martin S.

    1994-01-01

    Apparatus for the cutting of garment patterns from one or more layers of fabric. A laser capable of producing laser light at an ultraviolet wavelength is utilized to shine light through a pattern, such as a holographic phase filter, and through a lens onto the one or more layers of fabric. The ultraviolet laser light causes rapid photochemical decomposition of the one or more layers of fabric, but only along the pattern. The balance of the fabric of the one or more layers of fabric is undamaged.

  13. Forest-atmosphere BVOC exchange in diverse and structurally complex canopies: 1-D modeling of a mid-successional forest in northern Michigan

    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.

  14. Forest-atmosphere BVOC exchange in diverse and structurally complex canopies: 1-D modeling of a mid-successional forest in northern Michigan

    SciTech Connect

    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.

  15. On the origin of the ionosphere at the Moon using results from Chandrayaan-1 S band radio occultation experiment and a photochemical model

    NASA Astrophysics Data System (ADS)

    Choudhary, R. K.; Ambili, K. M.; Choudhury, Siddhartha; Dhanya, M. B.; Bhardwaj, Anil

    2016-10-01

    The origin of the Moon's ionosphere has been explored using Chandrayaan-1 radio occultation (RO) measurements and a photochemical model. The electron density near the Moon's surface, obtained on 31 July 2009 (˜300 cm-3), is compared with results from a model which includes production and recombination of 16 ions, solar wind proton charge exchange, and the electron impact ionization. The model calculations suggest that in the absence of transport, inert ions, namely Ar+, Ne+, and He+, dominate lunar ionosphere (density ˜5 × 104 cm-3). Interaction with solar wind, however, leads to their complete removal (˜2-3 cm-3). Assuming the Moon's exosphere to have CO2, H2O, O, OH, H2, CH4, and CO molecules in addition to the inert gases, the model calculations suggest that the lunar ionosphere is dominated by molecular ions, namely H2O+, CO2+, and H3O+, with near-surface density ˜250 cm-3. We surmise that lunar ionosphere can be molecular in nature.

  16. Development and Validation of the Total HUman Model for Safety (THUMS) Version 5 Containing Multiple 1D Muscles for Estimating Occupant Motions with Muscle Activation During Side Impacts.

    PubMed

    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.

  17. Investigation of the photochemical changes of chlorogenic acids induced by ultraviolet light in model systems and in agricultural practice with Stevia rebaudiana cultivation as an example.

    PubMed

    Karaköse, Hande; Jaiswal, Rakesh; Deshpande, Sagar; Kuhnert, Nikolai

    2015-04-08

    Mono- and diacyl chlorogenic acids undergo photochemical trans-cis isomerization under ultraviolet (UV) irradiation. The photochemical equilibrium composition was established for eight selected derivatives. In contrast to all other dicaffeoylquinic acid derivatives, cynarin (1,3-dicaffeoylquinic acid) undergoes a [2 + 2] photochemical cycloaddition reaction, constituting a first example of Schmidt's law in a natural product family. The relevance of photochemical isomerization in agricultural practice was investigated using 120 samples of Stevia rebaudiana leave samples grown under defined cultivation conditions. Ratios of cis to trans chlorogenic acids were determined in leaf samples and correlated with climatic and harvesting conditions. The data indicate a clear correlation between the formation of cis-caffeoyl derivatives and sunshine hours prior to harvesting and illustrate the relevance of UV exposure to plant material affecting its phytochemical composition.

  18. Sensitivity testing of a 1-D calving criterion numerical model constrained by observations of post-LIA fluctuations of Kangiata Nunaata Sermia, SW Greenland

    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

  19. Electron Density and Two-Channel Neutron Emission Measurements in Steady-State Spherical Inertial-Electrostatically Confined Plasmas, with Review of the 1-D Kinetic Model

    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.

  20. A joint probability approach using a 1-D hydrodynamic model for estimating high water level frequencies in the Lower Rhine Delta

    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.

  1. Potential of high resolution satellite imagery, remote weather data and 1D hydraulic modeling to evaluate flood areas in Gonaives, Haiti

    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

  2. Developing a spatially and temporally resolved emission inventory for photochemical modeling in the City of Cape Town and assessing its uncertainty

    NASA Astrophysics Data System (ADS)

    Sowden, Miles; Cairncross, Eugene; Wilson, Gary; Zunckel, Mark; Kirillova, Elena; Reddy, Vis; Hietkamp, Sibbele

    In an urban environment where reactive pollutants are emitted, it is critically important that atmospheric chemistry be considered in modeling and air quality management including the evaluation of secondary pollutants such as ozone. This may be achieved through photochemical modeling, which is reliant on detailed, grid resolved emissions inventories. The US-EPA's approved Emissions Processing System (EPS) is used to develop a temporally and spatially resolved emissions inventory for the City of Cape Town for use in the Dynamic Air Pollution Prediction System (DAPPS). Included in this inventory are large and small point sources, mobile sources, and emissions from residential fuel burning and biogenic sources. Large point sources are usually well defined unlike the other source types that can have large uncertainties associated with them. In these circumstances, surrogate data are used to estimate emission rates. The FRamework for the Assessment of Uncertainties in Large-scale Emission INventories (FRAULEIN) approach to assessing uncertainty in the emissions inventory is adapted for DAPPS. A reasonable level of confidence exists for the characterization of large point sources but the two biggest source contributors namely vehicle and biogenic emissions, needs improvement.

  3. 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

  4. 1D Thermal-Hydraulic-Chemical (THC) Reactive transport modeling for deep geothermal systems: A case study of Groß Schönebeck reservoir, Germany

    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

  5. From Anti-greenhouse Effect of Solar Absorbers to Cooling Effect of Greenhouse Gases: A 1-D Radiative Convective Model Study

    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

  6. Polyimides by photochemical cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2005-01-01

    The novel polyimides of this invention are derived from Diels-Alder cyclopolymerization of photochemically generated bisdienes with dienophiles, such as bismaleimides, trismaleimides and mixtures thereof with maleimide end-caps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via Diels-Alder cycloaddition with appropriate dienophiles, e.g., bismaleimide and/or trismaleimides to give the corresponding polyimides in quantitative yields. When bismaleimides, trismaleimides or mixtures thereof with maleimide end-caps are used as the dienophile, the resulting polyimides have glass transition temperatures (Tg) as high as 300? C. Polyimide films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These novel polyimides are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of adhesives, electronic materials and films.

  7. Polyimides by Photochemical Cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2005-01-01

    The novel polyimides of this invention are derived from Diels-Alder cyclopolymerization of photochemically generated bisdienes with dienophiles, such as bismaleimides, trismaleimides and mixtures thereof with maleimide endcaps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via Diels-Alder cycloaddition with appropriate dienophiles, e.g., bismaleimide and/or trismaleimides to give the corresponding polyimides in quantitative yields. When bismaleimides, trismaleimides or mixtures thereof with maleimide end-caps are used as the dienophile, the resulting polyimides have glass transition temperatures (Tg) as high as 300 C. Polyimide films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These novel polyimides are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of adhesives, electronic materials and films.

  8. Reduction of the uncertainties in the water level-discharge relation of a 1D hydraulic model in the context of operational flood forecasting

    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

  9. Simultaneous statistical bias correction of multiplePM2.5 species from a regional photochemical grid model

    EPA Science Inventory

    In recent years environmental epidemiologists have begun utilizing regionalscale air quality computer models to predict ambient air pollution concentrations in health studies instead of or in addition to monitoring data from central sites. The advantages of using such models i...

  10. Air-snowpack exchange of bromine, ozone and mercury in the springtime Arctic simulated by the 1-D model PHANTAS - Part 2: Mercury and its speciation

    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

  11. The application of forest classification from Landsat data as a basis for natural hydrocarbon emission estimation and photochemical oxidant model simulations in southeastern Virginia

    NASA Technical Reports Server (NTRS)

    Salop, J.; Wakelyn, N. T.; Levy, G. F.; Middleton, W. M.; Gervin, J. C.

    1983-01-01

    The possible contribution by natural hydrocarbon emissions to the total ozone budget recorded in the Tidewater region of southeastern Virginia during the height of the summer period was examined. Natural sources investigated were limited to the primary HC emitters and most prevalent natural vegetation, the forests. Three types and their areal coverage were determined for Region VI of the Virginia State Air Pollution Control Board using remotely sensed data from Landsat, a NASA experimental earth resources satellite. Emission factors appropriate to the specific types (coniferous 0.24 x 10 to the 13th, mixed 0.63 x 10 to the 13th, deciduous 1.92 x 10 to the 13th, microgram/h), derived from contemporary procedures, were applied to produce an overall regional emission rate of 2.79 x 10 to the 13th microgram/h for natural non-methane hydrocarbons (NMHC). This rate was used with estimates of the anthropogenic NO(x) and NMHC loading, as input into a photochemical box model. Additional HC loading on the order of that estimated to be produced by the natural forest communities was required in order to reach certain measured summer peak ozone levels as the computer simulation was unable to account for the measured episodic levels on the basis of the anthropogenic inventory alone.

  12. Alteration minerals, fluids, and gases on early Mars: Predictions from 1-D flow geochemical modeling of mineral assemblages in meteorite ALH 84001

    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.

  13. Parameterized isoprene and monoterpene emissions from the boreal forest floor: Implementation into a 1D chemistry-transport model and investigation of the influence on atmospheric chemistry

    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.

  14. Photochemical weathering and contemporary volatile loss on Mars

    NASA Technical Reports Server (NTRS)

    Huguenin, R. L.

    1987-01-01

    In an earlier series of papers by the author it was proposed that photochemical weathering of Fe(2+) in magnetite and in mafic silicates may be occurring in the contemporary surface environment with a resultant loss of O2 from the atmosphere. Morris and Lauer challenged the photochemical weathering model, proposing that oxidation by radiant heating rather than UV photoelectron emission induced oxidation may have dominated in the authors experiments. Subsequent laboratory studies of photochemical weathering of magnetite described here support the authors original proposal that UV illunimation can indeed drive the oxidation of magnetite under contemporary Martian surface conditions. The negative results of the Morris and Lauer study can now be explained.

  15. 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.

  16. A better understanding of hydroxyl radical photochemical sources in cloud waters collected at the puy de Dôme station - experimental versus modelled formation rates

    NASA Astrophysics Data System (ADS)

    Bianco, A.; Passananti, M.; Perroux, H.; Voyard, G.; Mouchel-Vallon, C.; Chaumerliac, N.; Mailhot, G.; Deguillaume, L.; Brigante, M.

    2015-08-01

    The oxidative capacity of the cloud aqueous phase is investigated during three field campaigns from 2013 to 2014 at the top of the puy de Dôme station (PUY) in France. A total of 41 cloud samples are collected and the corresponding air masses are classified as highly marine, marine and continental. Hydroxyl radical (HO•) formation rates (RHO•f) are determined using a photochemical setup (xenon lamp that can reproduce the solar spectrum) and a chemical probe coupled with spectroscopic analysis that can trap all of the generated radicals for each sample. Using this method, the obtained values correspond to the total formation of HO• without its chemical sinks. These formation rates are correlated with the concentrations of the naturally occurring sources of HO•, including hydrogen peroxide, nitrite, nitrate and iron. The total hydroxyl radical formation rates are measured as ranging from approximately 2 × 10-11 to 4 × 10-10 M s-1, and the hydroxyl radical quantum yield formation (ΦHO•) is estimated between 10-4 and 10-2. Experimental values are compared with modelled formation rates calculated by the model of multiphase cloud chemistry (M2C2), considering only the chemical sources of the hydroxyl radicals. The comparison between the experimental and the modelled results suggests that the photoreactivity of the iron species as a source of HO• is overestimated by the model, and H2O2 photolysis represents the most important source of this radical (between 70 and 99 %) for the cloud water sampled at the PUY station (primarily marine and continental).

  17. SLOWMOVE - A numerical model for the propagation of slow-moving landslides: a 1D approach and its application to the analysis of the Valoria landslide (Apennines, Italy)

    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

  18. Dynamics of ozone and nitrogen oxides at Summit, Greenland. II. Simulating snowpack chemistry during a spring high ozone event with a 1-D process-scale model

    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.

  19. Early alterations in energy metabolism in the hippocampus of APPswe/PS1dE9 mouse model of Alzheimer's disease.

    PubMed

    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

  20. Applying 1D Sediment Models to Reservoir Flushing Studies: Measuring, Monitoring, and Modeling the Spencer Dam Sediment Flush with HEC-RAS

    DTIC Science & Technology

    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

  1. Photochemically Synthesized Polyimides

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.; Tyson, Daniel S.

    2008-01-01

    An alternative to the conventional approach to synthesis of polyimides involves the use of single monomers that are amenable to photopolymerization. Heretofore, the synthesis of polyimides has involved multiple-monomer formulations and heating to temperatures that often exceed 250 C. The present alternative approach enables synthesis under relatively mild conditions that can include room temperature. The main disadvantages of the conventional approach are the following: Elevated production temperatures can lead to high production costs and can impart thermal stresses to the final products. If the proportions of the multiple monomeric ingredients in a given batch are not exactly correct, the molecular weight and other physical properties of the final material could be reduced from their optimum or desired values. To be useful in the alternative approach, a monomer must have a molecular structure tailored to exploit Diels-Alder trapping of a photochemically generated ortho-quinodimethane. (In a Diels-Alder reaction, a diene combines with a dienophile to form molecules that contain six-membered rings.) In particular, a suitable monomer (see figure) contains ortho-methylbenzophenone connected to a dienophile (in this case, a maleimide) through a generic spacer group. Irradiation with ultraviolet light gives rise to a photochemical intermediate the aforementioned ortho-quinodimethane from the ortho-methylbenzophenone. This group may react with the dienophile on another such monomer molecule to produce an oligomer that, in turn may react in a stepgrowth manner to produce a polyimide. This approach offers several advantages in addition to those mentioned above: The monomer can be stored for a long time because it remains unreactive until exposed to light. Because the monomer is the only active starting ingredient, there is no need for mixing, no concern for ensuring correct proportions of monomers, and the purity of the final product material is inherently high. The use

  2. Measurement and Modeling of Optical, Physical, and Photochemical Processes in the Open-Ocean Mixed Layer: Peroxide and Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Sikorski, Richard J.

    The goals of this work were to model H _2O_2 cycling in aquatic systems, and to study the photoproperties of bulk dissolved organic matter (DOM). H_2O _2 is produced photochemically from DOM with an "apparent" quantum yield (AQY; normalized to DOM absorbance) which decreases exponentially as wavelength increases. The primary task of this project was to develop a vertical-flux model of undersea irradiance (300-500 nm). The model varied the path-length and geometry of undersea light with solar zenith angle according to scattering in the atmosphere and water column, and according to the ratio of collimated light to diffuse light. This optical model was then combined with a one-dimensional model of marine surface mixing, which derived structure and dynamics by applying empirically determined stability limits to calculated bulk turbulent kinetic energy and shear turbulence. Using data collected in the eastern Caribbean during 1988, modeled H_2O _2 mixed-layer depth and diel distributions were controlled by mixing dynamics. Preliminary model results made it possible to identify two classes of photoproductive waters, based on the ratio of UV DOM absorption, 330 nm, to visible absorption, 460 nm. H_2O _2 photoproduction was primarily due to 320-360 nm irradiance in the model, while a surprisingly significant fraction of total production occurred at wavelengths greater than 400 nm at depth and at zenith angles greater than 15 degrees. The diel photoproduction of H _2O_2 was notably deeper at midday than would be predicted in a simple non -scattering optical model. DOM fluorescence decayed with irradiation above 330 nm, and intensified with irradiation below 330 nm. The processes were partially photo-reversible, and also reversed slowly in the dark. For new river input, irradiation at 296.7 nm initially bleached fluorescence, with re-intensification occurring upon longer irradiation at the same wavelength. Full -spectral solar irradiation bleached fluorescence. The rates of

  3. Analytical model of solutions of (2+1)-D heat convection equations in a shape memory alloy device immersed in a blood vessel

    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

  4. Polyesters by Photochemical Cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2002-01-01

    The polyesters of this invention are derived from a Diels-Alder cyclopolymerization of a photochemically generated bisdiene with dienophiles, such as di(acrylates), tri (acrylates), di(methacrylates), tri(methacrylates) and mixtures thereof with mono(methacrylates) or mono(acrylate) end-caps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via a Diels-Alder cycloaddition with appropriate dienophiles, e.g., di(acrylates) to give the corresponding in polyesters quantitative yields. When di(acrylates), tri(acrylates) and di and tri(methacrylates) or mixtures thereof with monoacrylate end-caps are used as the dienophile, the resulting polyesters have glass transition temperatures (Tg) as high as 200 C. Polyesters films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These polyesters, i.e. polyesters are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of composites, adhesives, electronic materials and films.

  5. Polyimides by Photochemical Cyclopolymerization

    NASA Technical Reports Server (NTRS)

    Meador, Michael A. (Inventor)

    2003-01-01

    The polyimides of this invention are derived from a Diels-Alder cyclopolymerization of a photochemically generated bisdiene with dienophiles, such as bismaleimides, trismaleimides and mixtures thereof with maleimide end-caps. Irradiation of one or more diketones produces two distinct hydroxy o-quinodimethane (photoenol) intermediates. These intermediates are trapped via a Diels-Alder cycloaddition with appropriate dienophiles, e.g., bismaleimide and/or trismaleimides to give the corresponding polyimides in quantitative yields. When bismaleimides, trismaleimides or mixtures thereof with maleimide end-caps are used as the dienophile, the resulting polyimides have glass transition temperatures (Tg) as high as 300 C. Polyimide films can be prepared by ultraviolet irradiation of high solids content varnishes of the monomers in a small amount of solvent, e.g., cyclohexanone, dimethyl formamide, N-methylpyrollidone and the like. These polyimides are characterized as having high glass transition temperatures, good mechanical properties and improved processing in the manufacture of adhesives, electronic materials and films.

  6. Assessing the photochemical impact of snow NOx emissions over Antarctica during ANTCI 2003

    NASA Astrophysics Data System (ADS)

    Wang, Yuhang; Choi, Yunsoo; Zeng, Tao; Davis, Douglas; Buhr, Martin; Gregory Huey, L.; Neff, William

    Surface and aircraft measurements show large amounts of reactive nitrogen over the Antarctic plateau during the ANTCI 2003 experiment. We make use of 1-D and 3-D chemical transport model simulations to analyze these measurements and assess the photochemical impact of snow NOx emissions. Boundary layer heights measured by SODAR at the South Pole were simulated reasonably well by the polar version of MM5 after a modification of ETA turbulence scheme. The average of model-derived snow NOx emissions (3.2-4.2×108moleccm-2s-1) at the South Pole is similar to the measured flux of 3.9×108moleccm-2s-1 during ISCAT 2000. Daytime snow NOx emission is parameterized as a function of temperature and wind speed. Surface measurements of NO, HNO3 and HNO4, and balloon measurements of NO at the South Pole are reasonably simulated by 1-D and 3-D models. Compared to Twin Otter measurements of NO over plateau regions, 3-D model simulated NO concentrations are at the low end of the observations, suggesting either that the parameterization based on surface measurements at the South Pole underestimates emissions at higher-elevation plateau regions or that the limited aircraft database may not be totally representative for the season of the year sampled. However, the spatial variability of near-surface NO measured by the aircraft is captured by the model to a large extent, indicating that snow NOx emissions are through a common mechanism. An average emission flux of 0.25kgNkm-2month-1 is calculated for December 2003 over the plateau (elevation above 2.5 km). About 50% of reactive nitrogen is lost by deposition and the other 50% by transport. The 3-D model results indicate a shallow but highly photochemically active oxidizing "canopy" enshrouding the entire Antarctic plateau due to snow NOx emissions.

  7. Monte carlo estimates of uncertainties in predictions by a photochemical grid model (UAM-IV) due to uncertainties in input variables

    NASA Astrophysics Data System (ADS)

    Hanna, Steven R.; Chang, Joseph C.; Fernau, Mark E.

    Because photochemical grid models such as UAM-IV are being used to make policy decisions concerning emissions controls, it is important to know (1) the uncertainties in the model predictions due to the combined effects of uncertainties in the full set of input variables, and (2) the individual input parameters whose variations have the greatest effect on variations in model predictions. A preliminary Monte Carloun certainty analysis system has been developed and the methodology has been demonstrated using anapplication of the standard U.S. regulatory model, UAM-IV, to the 230 km by 290 km New York City domain for the 6-8 July 1988 ozone episode. As a first step, ten modeling experts were asked to estimate the typical uncertainties of 109 UAM-IV input parameters, including 23 variables related to emissions, boundary conditions, and meteorological conditions; and 86 variables related to chemical rate constants. For many of the model inputs, the assumed range of uncertainty was about plus or minus 30% of a normal mid-range value, and, in most cases, the distributions were assumed to have a log-normal shape. The regulatory agency's "base run" application of UAM-IV to this ozone episode was used to define the mid-range or median values of all input parameters. 50 Monte Carlo UAM-IV runs were then carried out by simple random sampling of each of the 109 input parameters from the assumed distributions. The 50 predicted values of peak hourly averaged ozone concentrations anywhere on the geographic domain for the episode were found to follow a log-normal distribution and exhibit a variability from 176 to 331 ppb. The locations of the 50 predicted ozone peaks varied from 100 km upwind (southwest) of New York City to 150 km down wind (northeast) of the city. Variability in the input parameter known as the anthropogenic volatile organic compound (VOC) area source emissions had the most influence on the variations in the 50 predicted peak ozone concentrations.

  8. Solar photochemical oxidation of alcohols using catalytic hydroquinone and copper nanoparticles under oxygen: oxidative cleavage of lignin models.

    PubMed

    Mitchell, Lorna J; Moody, Christopher J

    2014-11-21

    Alcohols are converted into to their corresponding carbonyl compounds using catalytic amounts of 1,4-hydroquinone with a copper nanoparticle electron transfer mediator with oxygen as the terminal oxidant in acetone as solvent under visible light irradiation. These conditions employing biorenewable hydroquinone as reagent were developed from initial experiments using stoichiometric amounts of 1,4-benzoquinone as oxidant. A range of benzylic and aliphatic primary and secondary alcohols are oxidized, affording the corresponding aldehydes or ketones in moderate to excellent yields. The methodology is also applicable to the oxidative degradation of lignin model compounds that undergo C-C bond cleavage to give simple aromatic compounds.

  9. The lithosphere-asthenosphere system beneath Ireland from integrated geophysical-petrological modeling - I: Observations, 1D and 2D hypothesis testing and modeling

    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

  10. Hairlike Percutaneous Photochemical Sensors

    NASA Technical Reports Server (NTRS)

    George, Thomas; Loeb, Gerald

    2004-01-01

    Instrumentation systems based on hairlike fiber-optic photochemical sensors have been proposed as minimally invasive means of detecting biochemicals associated with cancer and other diseases. The fiber-optic sensors could be mass-produced as inexpensive, disposable components. The sensory tip of a fiber-optic sensor would be injected through the patient's skin into subcutaneous tissue. A biosensing material on the sensory tip would bind or otherwise react with the biochemical(s) of interest [the analyte(s)] to produce a change in optical properties that would be measured by use of an external photonic analyzer. After use, a fiber-optic sensor could be simply removed by plucking it out with tweezers. A fiber-optic sensor according to the proposal would be of the approximate size and shape of a human hair, and its sensory tip would resemble a follicle. Once inserted into a patient's subcutaneous tissue, the sensor would even more closely resemble a hair growing from a follicle (see Figure 1). The biosensing material on the sensory tip could consist of a chemical and/or cells cultured and modified for the purpose. The biosensing material would be contained within a membrane that would cover the tip. If the membrane were not permeable by an analyte, then it would be necessary to create pores in the membrane that would be large enough to allow analyte molecules to diffuse to the biosensing material, but not so large as to allow cells (if present as part of the biosensing material) to diffuse out. The end of the fiber-optic sensor opposite the sensory tip would be inserted in a fiberoptic socket in the photonic analyzer.

  11. Episodic-like memory deficits in the APPswe/PS1dE9 mouse model of Alzheimer's disease: relationships to beta-amyloid deposition and neurotransmitter abnormalities.

    PubMed

    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.

  12. Contribution of regional-scale fire events to ozone and PM2.5 air quality estimated by photochemical modeling approaches

    NASA Astrophysics Data System (ADS)

    Baker, K. R.; Woody, M. C.; Tonnesen, G. S.; Hutzell, W.; Pye, H. O. T.; Beaver, M. R.; Pouliot, G.; Pierce, T.

    2016-09-01

    Two specific fires from 2011 are tracked for local to regional scale contribution to ozone (O3) and fine particulate matter (PM2.5) using a freely available regulatory modeling system that includes the BlueSky wildland fire emissions tool, Spare Matrix Operator Kernel Emissions (SMOKE) model, Weather and Research Forecasting (WRF) meteorological model, and Community Multiscale Air Quality (CMAQ) photochemical grid model. The modeling system was applied to track the contribution from a wildfire (Wallow) and prescribed fire (Flint Hills) using both source sensitivity and source apportionment approaches. The model estimated fire contribution to primary and secondary pollutants are comparable using source sensitivity (brute-force zero out) and source apportionment (Integrated Source Apportionment Method) approaches. Model estimated O3 enhancement relative to CO is similar to values reported in literature indicating the modeling system captures the range of O3 inhibition possible near fires and O3 production both near the fire and downwind. O3 and peroxyacetyl nitrate (PAN) are formed in the fire plume and transported downwind along with highly reactive VOC species such as formaldehyde and acetaldehyde that are both emitted by the fire and rapidly produced in the fire plume by VOC oxidation reactions. PAN and aldehydes contribute to continued downwind O3 production. The transport and thermal decomposition of PAN to nitrogen oxides (NOX) enables O3 production in areas limited by NOX availability and the photolysis of aldehydes to produce free radicals (HOX) causes increased O3 production in NOX rich areas. The modeling system tends to overestimate hourly surface O3 at routine rural monitors in close proximity to the fires when the model predicts elevated fire impacts on O3 and Hazard Mapping System (HMS) data indicates possible fire impact. A sensitivity simulation in which solar radiation and photolysis rates were more aggressively attenuated by aerosol in the plume

  13. Photochemical aspects related to humic substances

    SciTech Connect

    Frimmel, F.H. )

    1994-01-01

    Dissolved humic substances (HS) show yellow color and relatively strong absorption in the UV range [a(254 nm) ca. 0.04 cm[sup [minus]1] for c(DOC) = 1 mg/L]. This is the basis for photochemical reactions in the photic zone of aquatic systems and in water treatment using IV sources. Even though understanding the mechanisms involved in the energy transfer and the resulting reactions is hampered by the poorly defined structure of HS, reliable information has been gathered on some typical aspects of their photochemistry. The luminescence of HS can be influenced and partly quenched by molecular interactions with other water constituents (e.g., heavy metals and organic micropollutants). The presence of oxygen may lead to the sensitized production of singlet oxygen (O[sub 2]), that can react specifically with substances containing diene structures or low valent sulfur. Because of the presence of these structures in HS, humic molecules will also react with the sensitized products. As a consequence, their biological, chemical, and physical properties are influenced. In addition, HS have a significant impact on the photochemical treatment of organic micropollutants in water. This has to be kept in mind when using photochemical steps for water treatment. The results from model experiments reflecting the conditions in surface water and in water treatment are given and discussed. In the presence of H[sub 2]O[sub 2], irradiation led to a transformation and partial degradation of HS. The rate of photochemical degradation of pesticides (e.g., atrazine) was decreased in the presence of HS. Fe and Mn quenched the luminescence. From this, a decrease of excited states of HS for sensitizing reactions can be deduced. The results suggest the manyfold and significant influences of HS on the photochemistry of aquatic systems. 66 refs., 9 figs., 7 tabs.

  14. Spring time photochemical air pollution in Osaka

    SciTech Connect

    Wakamatsu, Shinji; Uno, Itsushi; Ohara, Toshimasa

    1996-12-31

    High concentrations of nitrogen dioxide are frequently observed in Osaka area in spring season. To clarify this, a series of three dimensional field observation was conducted in April 1993 covering Osaka and surrounding area. Vertical and horizontal distributions of ozone, NO, NO{sub x}, SO{sub 2}, CO, aerosol species, hydrocarbon species and meteorological parameter such as temperature, uv radiation, wind speed, wind direction are measured on the ground and aloft. Covering the observational period yellow sand transportation from the continent and stratospheric ozone intrusion were also observed under the meteorological condition of moving high pressure system. During the aircraft observation of 19 to 21 April 1993 high concentration of photochemical air pollution was observed aloft over Osaka area. Maximum ozone concentration was me than 150 ppb. Vertical distribution of ozone showed uniform profile up to 2500m in day time. At Mt. Ikoma (600 m) ozone concentration had been almost constant ranging 80-100 ppb throughout the observational period. To clarify this phenomena three dimensional photochemical air pollution simulation model was applied based on the real meteorological and emission conditions. Simulated result showed photochemical reaction play an important role to form the spring time high concentrations of nitrogen dioxide in Osaka.

  15. Research opportunities in photochemical sciences

    SciTech Connect

    1996-07-01

    The workshop entitled {open_quotes}Research Opportunities in Photochemical Sciences{close_quotes} was initiated by the U.S. Department of Energy (DOE), Office of Energy Research (ER), Office of Basic Energy Sciences (BES), Division of Chemical Sciences. The National Renewable Energy Laboratory (NREL) in Golden, Colorado was requested by ER to host the workshop. It was held February 5-8, 1996 at the Estes Park Conference Center, Estes Park, CO, and attended by about 115 leading scientists and engineers from the U.S., Japan, and Europe; program managers for the DOE ER and Energy Efficiency and Renewable Energy (EERE) programs also attended. The purpose of the workshop was to bridge the communication gap between the practioneers and supporters of basic research in photochemical science and the practioneers and supporters of applied research and development in technologies related to photochemical science. For the purposes of the workshop the definition of the term {open_quotes}photochemical science{close_quotes} was broadened to include homogeneous photochemistry, heterogeneous photochemistry, photoelectrochemistry, photocatalysis, photobiology (for example, the light-driven processes of biological photosynthesis and proton pumping), artificial photosynthesis, solid state photochemistry, and solar photochemistry. The technologies under development through DOE support that are most closely related to photochemical science, as defined above, are the renewable energy technologies of photovoltaics, biofuels, hydrogen energy, carbon dioxide reduction and utilization, and photocatalysis for environmental cleanup of water and air. Individual papers were processed separately for the United states Department of Energy databases.

  16. Investigating ambient ozone formation regimes in neighboring cities of shale plays in the Northeast United States using photochemical modeling and satellite retrievals

    NASA Astrophysics Data System (ADS)

    Chang, Chih-Yuan; Faust, Eric; Hou, Xiangting; Lee, Pius; Kim, Hyun Cheol; Hedquist, Brent C.; Liao, Kuo-Jen

    2016-10-01

    This study investigates long-term (i.e., 2007-2014) fluctuations in ambient ozone formation regimes for cities adjacent to shale plays in the Northeast United States (U.S.). Ozone air quality in many cities of the Northeast U.S. does not meet the U.S. National Ambient Air Quality Standards (NAAQS), and understanding ambient ozone formation regimes is essential to develop effective air pollution mitigation strategies for cities violating the air quality standards. Since 2013, the U.S. has become the world's largest producer of tight oil and natural gas from shale rock, and previous studies show that emissions of air pollutant precursors from shale oil and gas-related activities would have the potential to affect ambient ozone air quality in adjacent cities of shale plays. This work leveraged (1) satellite-retrieved column densities of formaldehyde (HCHO) and nitrogen dioxide (NO2) from multiple instruments (i.e., Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment-2 (GOME-2)); (2) photochemical air quality modeling and sensitivity analysis; and (3) ratios of satellite-retrieved air pollutant column densities to investigate ambient ozone formation regimes in neighboring cities of shale plays (i.e., Marcellus Shale) in the Northeast U.S. from 2007 to 2014. Our results show that ambient ozone formation in Boston, Pittsburgh, Philadelphia and Washington, D.C. (which are close to Marcellus Shale) was in the NOx -limited or transition regime during the period of study. Ambient ozone formation in New York City was in the transition regime during 2010-2013 and VOC -limited regime during 2007-2009 and in 2014. Based on the result of this study, we conclude that controls NOx emissions would mitigate ozone air pollution from 2007 to 2014 in most of the cities examined in this study. Controls of local VOC emissions would ease ozone air pollution in New York City during the study period. With projected increases in oil and gas production from shale plays in

  17. Photochemical Attenuation of Pesticides in Prairie Potholes

    NASA Astrophysics Data System (ADS)

    Zeng, T.; Arnold, W. A.

    2013-12-01

    DOM appeared to exert the largest effects on the overall photodegradation. Furthermore, a suite of second-order rate constants for reactions of pesticides with PPRIs were derived based on the quenching effect on observed reaction rate constants and measured steady-state concentrations of PPRIs. These rate constants may find practical utility for estimating DOM photochemical reaction rates in addition to data traditionally estimated from model compounds. Overall, our work contributed to a systematic evaluation of the potential for photochemical attenuation of pesticides in near-surface pothole water. Given recent incentives to expand agriculture in the PPR for production of organic crops and corn-based biofuels, this research also calls for the need to properly conserve prairie potholes and to develop regionally-specific, sustainable water resource management and land use strategies.

  18. Stratospheric NO and NO2 profiles at sunset from analysis of high-resolution balloon-borne infrared solar absorption spectra obtained at 33 deg N and calculations with a time-dependent photochemical model

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Boughner, R. E.; Larsen, J. C.; Goldman, A.; Murcray, F. J.; Murcray, D. G.

    1984-01-01

    Simultaneous stratospheric vertical profiles of NO and NO2 at sunset were derived from an analysis of infrared solar absorption spectra recorded from a float altitude of 33 km with an interferometer system during a balloon flight. A nonlinear least squares procedure was used to analyze the spectral data in regions of absorption by NO and NO2 lines. Normalized factors, determined from calculations of time dependent altitude profiles with a detailed photochemical model, were included in the onion peeling analysis to correct for the rapid diurnal changes in NO and NO2 concentrations with time near sunset. The CO2 profile was also derived from the analysis and is reported.

  19. The effect of knockout of sulfotransferases 1a1 and 1d1 and of transgenic human sulfotransferases 1A1/1A2 on the formation of DNA adducts from furfuryl alcohol in mouse models.

    PubMed

    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.

  20. Observations and analysis of O(1D) and NH2 line profiles for the coma of comet P/Halley

    NASA Technical Reports Server (NTRS)

    Smyth, William H.; Combi, Michael R.; Roesler, Fred L.; Scherb, Frank

    1995-01-01

    A set of high-resolution Fabry-Perot measurements of the coma of comet P/Halley was acquired in the (O I) 6300 A and NH2 6298.62 A emission lines. These high-resolution measurements provide the first optical observations capable of studying directly the photochemical kinetics and dynamic outflow of the coma. The observations were analyzed by a Monte Carlo Particle Trajectory Model. The agreement of the model and observed line profiles was excellent and verified the underlying dynamics, exothermic photodissociative chemistry, and collisional thermalization in the coma. The somewhat wider intrinsic line profile width for the O(1D) emission in 1986 January compared to 1986 May, is, for example, produced by the larger outflow speeds and gas temperatures nearer perihelion in January. The January O(1D) profile, which is wider than the January NH2 profile, is indicative of the photochemical kinetics in the dissociation of the parent molecules H2O and OH in the coma. The absolute calibration of the observations in 1986 January allowed the production rates for H2O and the NH2-parent molecules to be determined. The average daily water production rates derived from the O(1D) emission data for January 16 and 17 are presented. These very large water production rates are consistent with the extrapolated (and 7.6 day time variable) water production rates determined from the analysis of lower spectral resolution observations for O(1D) and H-alpha emissions that covered the time period up to January 13. The large production rates on January 16 and 17 establish that the maximum water production rate for comet Halley accurred pre-perihelion in January. Implications drawn from comparison with 18 cm radio emission data in January suggest that the peak water production rate was even larger. The average production rate for NH3 determined from the NH2 emission data for January 17 was (1.48 +/- 0.10) x 10(exp 28) molecules/s, yielding an NH3/H2O production rate ratio of 0.55%.

  1. Approximate photochemical dynamics of azobenzene with reactive force fields

    SciTech Connect

    Li, Yan; Hartke, Bernd

    2013-12-14

    We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis→trans- and trans→cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work)

  2. Approximate photochemical dynamics of azobenzene with reactive force fields

    NASA Astrophysics Data System (ADS)

    Li, Yan; Hartke, Bernd

    2013-12-01

    We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis→trans- and trans→cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work).

  3. Validating a 1-D SVAT model in a range of USA and Australian ecosystems: evidence towards its use as a tool to study Earth's system interactions

    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

  4. Photochemical functionalization of diamond surfaces

    NASA Astrophysics Data System (ADS)

    Nichols, Beth Marie

    Diamond surfaces are excellent substrates for potential applications in fields such as biotechnology, molecular sensing, and molecular electronics. In order to develop new diamond-based technologies, it is important to develop a fundamental understanding of diamond surface chemistry. Previous work in the Hamers group has demonstrated covalent functionalization of hydrogen-terminated diamond surfaces with molecules bearing a terminal vinyl group via a photochemical process using sub-bandgap light at 254 nm. While the reaction was shown to occur reproducibly with self-terminating monolayer surface coverage, the mechanism was never fully understood. This thesis investigates the photochemical modification of hydrogen-terminated surfaces of diamond. The results show that this reaction is a surface-mediated radical process initiated by the UV-assisted photoejection of electrons from the diamond surfaces into the liquid phase. To develop a better understanding of the photochemical mechanism, an electrical bias was applied to the diamond samples during the photochemical reaction. Applying a 1 volt potential between two diamond electrodes significantly increases the rate of functionalization of the negative electrode. Cyclic voltammetry and electrochemical impedance measurements show that the applied potential induces downward band-bending within the negative diamond film electrode. At higher voltages a Faradaic current is observed, with no further acceleration of the functionalization rate. The bias-dependent changes in rate are attributed to a field effect; the applied potential induces a downward band-bending on the negative electrode and facilitates electron ejection into the adjacent organic fluid. The ability to directly organically photopattern the surface on length scales of <25 microns has also been demonstrated using simple photomasking techniques. Techniques for the functionalization of diamond may be applied to other 'unreactive' surfaces. The activation of a

  5. The coupling of WEPP and 3ST1D numerical models for improved estimation of runoff and sediment yield at watershed scales

    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...

  6. Comparative evaluation of 1D and quasi-2D hydraulic models based on benchmark and real-world applications for uncertainty assessment in flood mapping

    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.

  7. Modeling of the D1/D2 proteins and cofactors of the photosystem II reaction center: implications for herbicide and bicarbonate binding.

    PubMed Central

    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

  8. A numerical method based on the Fourier-Fourier transform approach for modeling 1-D electron plasma evolution. [in earth bow shock region

    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.

  9. Effects of Spinal and Peripheral Injection of α1A or α1D Adrenoceptor Antagonists on Bladder Activity in Rat Models with or without Bladder Outlet Obstruction

    PubMed Central

    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

  10. Complex Equilibria Changing in Photochemical Reaction: Computerized Evaluation and Simulation.

    ERIC Educational Resources Information Center

    Horvath, Otto; Papp, Sandor

    1988-01-01

    States that if photochemical reactions can be followed spectrophotometrically, reactivities can be estimated by evaluating data from only one curve. Studies such a system using computerized evaluation and simulation. Uses chlorocuprate(II) complexes in acetonitrile solutions for the model systems. (MVL)

  11. A preliminary 1-D model investigation of tidal variations of temperature and chlorinity at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge

    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.

  12. Seasonal enhancement of submarine groundwater discharge (SGD)-derived nitrate loading into the Ria Formosa coastal lagoon assessed by 1-D modeling of benthic NO3- profiles

    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.

  13. Mapping deep-sea hydrothermal deposits with an in-loop transient electromagnetic method: Insights from 1D forward and inverse modeling

    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.

  14. Regional subsidence modelling in Murcia city (SE Spain) using 1-D vertical finite element analysis and 2-D interpolation of ground surface displacements

    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.

  15. Validation of the emission inventory in the Sao Paulo Metropolitan Area of Brazil, based on ambient concentrations ratios of CO, NMOG and NO x and on a photochemical model

    NASA Astrophysics Data System (ADS)

    Vivanco, Marta G.; Andrade, Maria de Fátima

    In recent years, photochemical air pollution has become a significant problem in the São Paulo Metropolitan Area (SPMA). For some air pollutants, especially ozone and particulate matter, concentrations in excess of national air quality standards have been registered. According to data published by the State Environmental Agency (CETESB), approximately 90% of ozone precursors are emitted into the atmosphere by the vehicle fleet [CETESB, 2000. Relatório de Qualidade do ar do Estado de Sao Paulo, 1999; CETESB, 2002. Relatório de Qualidade do ar do Estado de Sao Paulo, 2004]. The estimation of precursor emissions speciation is a rather complex task. Estimating spatial and temporal variation of vehicle emissions is the greatest source of uncertainty. As in other locales, data regarding motor vehicle emissions are scarce. Due to the considerable discrepancies in emission inventories reported in various regions of the world, we evaluated the official emission inventories of non-methane organic gas (NMOG) and nitrogen oxides (NO x) using an observation-based approach. Ratios of NO x/carbon monoxide (CO) and NMOG/CO were calculated from ambient measurements taken in the early morning (0700-0800) during July and August of 1999. This top-down approach assumes that early morning ambient concentrations of CO, NO x and NMOG are dominated by motor vehicle emissions, and that the photochemical process has not substantially affected the concentrations. Based on these ratios and on the assumption that official inventory of CO emissions is reasonably accurate, on-road motor vehicle emissions of NO x seem to be significantly overestimated and NMOG emissions slightly underestimated. An Eulerian photochemical model, using both the revised motor vehicle emission inventory and the original official emissions provided by CETESB, was applied to an episodic air pollution event in the SPMA (9-12 August 1999). Meteorology fields were obtained from the CALMET model. When the revised, rather

  16. Multiscale predictions of aviation-attributable PM2.5 for U.S. airports modeled using CMAQ with plume-in-grid and an aircraft-specific 1-D emission model

    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.

  17. Air-snowpack exchange of bromine, ozone and mercury in the springtime Arctic simulated by the 1-D model PHANTAS - Part 2: Mercury and its speciation

    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

  18. Quench in the 1D Bose-Hubbard model: topological defects and excitations from the Kosterlitz-Thouless phase transition dynamics.

    PubMed

    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.

  19. Subsurface Xenon Migration by Atmospheric Pumping Using an Implicit Non-Iterative Algorithm for a Locally 1D Dual-Porosity Model

    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.

  20. 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.

  1. The carbon-bond mechanism: a condensed kinetic mechanism for photochemical smog

    SciTech Connect

    Whitten, G.Z.; Hog, H.; Killus, J.P.

    1980-06-01

    Efforts to develop a model that can simulate photochemical smog with kinetic mechanisms are discussed. The carbon-bond mechanism is a set of generalized reactions that can be used to model photochemical oxidant formation. The theoretical framework of carbon-bond mechanism is outlined. Chemical variables that are incorporated into the carbon-bond mechanism model are described. Further work that is needed on the carbon-bond mechanism model is considered. (1 diagram, 13 graphs, 30 references, 2 tables)

  2. Photochemical air pollution. Part I

    SciTech Connect

    Goldstein E.; Hackney, J.D.; Rokaw, S.N.

    1985-03-01

    In this paper, epidemiologic studies are reported which indicate that high photochemical oxidant exposures: do not cause mortality or serious illness; may increase the risk of asthmatic attacks in a small percentage of asthmatic patients; appear to reduce pulmonary function in smokers and nonsmokers after long-term exposure; cause acute discomfort of eye and throat, chest irritation and cough; and interfere with athletic performance. Exposure to high ambient levels of NO/sub 2/ is not associated with mortality, serious disease or respiratory dysfunction, but self-limiting symptoms of respiratory irritation or illness may develop in children. 106 references, 2 figures, 1 table.

  3. Model Calculations on One-Dimensional (1D) Poly-Decker Sandwich Compounds. A Crystal Orbital Investigation Based on the Tight-Binding Formalism

    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

  4. Evaluation of the causes of inundation in a repeatedly flooded zone in the city of Cheongju, Korea, using a 1D/2D model.

    PubMed

    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

  5. Constraining Source Locations of Shallow Subduction Megathrust Earthquakes in 1-D and 3-D Velocity Models - A Case Study of the 2002 Mw=6.4 Osa Earthquake, Costa Rica

    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.

  6. Photochemical behaviour of phenylurea herbicides.

    PubMed

    Amine-Khodja, Amina; Boulkamh, Abdelaziz; Boule, Pierre

    2004-02-01

    The photochemical behaviour of phenylurea herbicides in aqueous solution is highly dependent on the nature and position of substituents on the ring. Most of these herbicides are methylated on the urea moiety, the other substituents are usually halogens or methoxy groups. The main reaction involving the aromatic ring of unhalogenated phenylureas excited at wavelengths shorter than 300 nm is an intramolecular rearrangement, similar to photo-Fries rearrangement, whereas with halogenated derivatives, photohydrolysis is the main transformation pathway. In the particular case of para-halogenated phenylureas, the intermediate formation of a carbene is observed. When the urea moiety is substituted with a methoxyl group, demethoxylation is a competitive reaction. N-Demethylation or oxidation of methyl groups is also observed, but with a lower yield. Photooxidation of phenylureas can also be induced by photocatalysis, iron salts or humic substances. In the absence of water, the main route for phototransformation of diuron is the oxidation or elimination of methyl groups. It is entirely possible that a photochemical intermediate could turn out to be more toxic than the initial herbicide.

  7. The photochemical role of tropospheric nitrogen oxides

    NASA Technical Reports Server (NTRS)

    Chameides, W. L.

    1978-01-01

    The role of nitrogen oxides in the tropospheric photochemical system is re-evaluated in the light of recent measurements of the rate constants for two key reactions. A model for nitrogen oxides is discussed which yields surface NO(x) (NO+NO2) levels approaching 1 ppb in NO(x) source regions but less than 0.1 ppb outside source regions. Applying the new rate coefficients implies increased radical concentrations and a more intense O3 and CO photochemistry. Even for densities of 0.1 ppb or less, NO(x) still leads to significant local O3 production and conversion of HO2 to OH. Unrealistic O3 profiles are obtained with the new rate coefficients for surface NO(x) densities of about 1 ppb, while reasonable agreement with observation is obtained with lower NO(x) densities. Feedback processes between CO, NO(x), OH, and CH4 are also discussed.

  8. Interaction of environmental contaminants with zebrafish organic anion transporting polypeptide, Oatp1d1 (Slco1d1)

    SciTech Connect

    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

  9. Influence of humidity on photochemical ozone generation with 172nm xenon excimer lamps

    NASA Astrophysics Data System (ADS)

    Salvermoser, M. J.; Kogelschatz, U.; Murnick, D. E.

    2009-08-01

    The reaction kinetics of photochemical ozone (O{3}) generation in humid air and oxygen (O{2}) using efficient, narrow band vacuum ultra violet (VUV) 172 nm xenon excimer lamps is discussed. Trace amounts of water (H{2}O) vapor in the process gas leads to hydroxyl (OH) and hydroperoxy (HO{2}) radical formation. These radicals drive a catalytic O{3} destruction cycle limiting O{3} saturation concentration. This catalytic O{3} destruction cycle was included into a quantitative kinetic model describing photochemical O{3} production. Experimental O{3} saturation concentrations obtained with coaxial VUV driven photochemical O{3} generators compare satisfactorily with the models predictions.

  10. Photochemical N-demethylation of alkaloids.

    PubMed

    Ripper, J A; Tiekink, E R; Scammells, P J

    2001-02-26

    Certain alkaloids were observed to undergo N-demethylation processes under photochemical conditions. Tropine, acetyltropine, tropinone, and atropine were cleanly N-demethylated upon treatment with tetraphenylporphin, oxygen, and light. Dextromethorphan also underwent a N-demethylation reaction, but reacted further to afford an imine. In contrast, 14-acyloxycodeinones underwent a photochemically induced tandem N-demethylation acyl migration.

  11. Photochemical processing of aqueous atmospheric brown carbon

    NASA Astrophysics Data System (ADS)

    Zhao, R.; Lee, A. K. Y.; Huang, L.; Li, X.; Yang, F.; Abbatt, J. P. D.

    2015-01-01

    Atmospheric Brown Carbon (BrC) is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report a series of laboratory studies of photochemical processing of BrC in the aqueous phase, by direct photolysis and OH oxidation. Solutions of ammonium sulfate mixed with glyoxal (GLYAS) or methylglyoxal (MGAS) are used as surrogates for a class of secondary BrC mediated by imine intermediates. Three nitrophenol species, namely 4-nitrophenol, 5-nitroguaiacol and 4-nitrocatechol, were investigated as a class of water soluble BrC originating from biomass burning. Photochemical processing induced significant changes in the absorptive properties of BrC. The imine-mediated BrC solutions exhibited rapid photo-bleaching with both direct photolysis and OH oxidation, with atmospheric half-lives of minutes to a few hours. The nitrophenol species exhibited photo-enhancement in the visible range during direct photolysis and the onset of OH oxidation, but rapid photo-bleaching was induced by further OH exposure on an atmospheric timescale of an hour or less. To illustrate atmospheric relevance of this work, we also performed direct photolysis experiments on water soluble organic carbon extracted from biofuel combustion samples and observed rapid changes in optical properties of these samples as well. Overall, these experiments indicate that atmospheric models need to incorporate representations of atmospheric processing of BrC species to accurately model their radiative impacts.

  12. Photochemical processing of aqueous atmospheric brown carbon

    NASA Astrophysics Data System (ADS)

    Zhao, R.; Lee, A. K. Y.; Huang, L.; Li, X.; Yang, F.; Abbatt, J. P. D.

    2015-06-01

    Atmospheric brown carbon (BrC) is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report on a series of laboratory studies of photochemical processing of BrC in the aqueous phase, by direct photolysis and OH oxidation. Solutions of ammonium sulfate mixed with glyoxal (GLYAS) or methylglyoxal (MGAS) are used as surrogates for a class of secondary BrC mediated by imine intermediates. Three nitrophenol species, namely 4-nitrophenol, 5-nitroguaiacol and 4-nitrocatechol, were investigated as a class of water-soluble BrC originating from biomass burning. Photochemical processing induced significant changes in the absorptive properties of BrC. The imine-mediated BrC solutions exhibited rapid photo-bleaching with both direct photolysis and OH oxidation, with atmospheric half-lives of minutes to a few hours. The nitrophenol species exhibited photo-enhancement in the visible range during direct photolysis and the onset of OH oxidation, but rapid photo-bleaching was induced by further OH exposure on an atmospheric timescale of an hour or less. To illustrate the atmospheric relevance of this work, we also performed direct photolysis experiments on water-soluble organic carbon extracted from biofuel combustion samples and observed rapid changes in the optical properties of these samples as well. Overall, these experiments indicate that atmospheric models need to incorporate representations of atmospheric processing of BrC species to accurately model their radiative impacts.

  13. Photochemical Copper Coating on 3D Printed Thermoplastics.

    PubMed

    Yung, Winco K C; Sun, Bo; Huang, Junfeng; Jin, Yingdi; Meng, Zhengong; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-08-09

    3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy.

  14. Photochemical Copper Coating on 3D Printed Thermoplastics

    PubMed Central

    Yung, Winco K. C.; Sun, Bo; Huang, Junfeng; Jin, Yingdi; Meng, Zhengong; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-01-01

    3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy. PMID:27501761

  15. Photochemical Copper Coating on 3D Printed Thermoplastics

    NASA Astrophysics Data System (ADS)

    Yung, Winco K. C.; Sun, Bo; Huang, Junfeng; Jin, Yingdi; Meng, Zhengong; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-08-01

    3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy.

  16. Inhalation of Photochemically Altered Urban Mixtures Depresses Cardiac Function in Mice

    EPA Science Inventory

    Rationale: Epidemiological studies have indicated an association between urban air pollution exposure and cardiovascular morbidity and mortality. The present study was designed to evaluate the cardiac effects of inhaled photochemical products in urban mixtures in a murine model. ...

  17. Developing Sediment Transport and Dredging Prediction Model of Ohio River at Olmsted Locks and Dams Area using HEC-RAS (1D/2D)By Ganesh Raj Ghimire1 and Bruce A. Devantier 2

    NASA Astrophysics Data System (ADS)

    Ghimire, G. R.

    2015-12-01

    Sediment deposition is a serious issue in the construction and operation of large reservoir and inland navigation projects in the United States and around the world. Olmsted Locks and Dams in the Ohio River navigation system is facing similar challenges of huge sediment deposition during the ongoing in-wet construction methodology since 1993. HEC-RAS 5.0 integrated with ArcGIS, will be used to yield unsteady 2D hydrodynamic model of Ohio River at Olmsted area. Velocity, suspended sediment, bed sediment and hydrographic survey data acquired from public archives of USGS and USACE Louisville District will be input into the model. Calibration and validation of model will be performed against the measured stage, flow and velocity data. It will be subjected to completely unsteady 1D sediment transport modeling new to HEC-RAS 5.0 which incorporates sediment load and bed gradation via a DSS file, commercial dredging and BSTEM model. Sediment model will be calibrated to replicate the historical bed volume changes. Excavated cross-sections at Olmsted area will also be used to predict the sediment volume trapped inside the ditch over the period between excavations and placement of dam shells at site. Model will attempt to replicate historical dredging volume data and compare with the deposition volume from simulation model to formulate the dredging prediction model. Hence, the results of this research will generate a model that can form a basis for scheduling the dredging event prior to the placement of off-shore cast shells replacing the current as and when required approach of dredging plan. 1 Graduate Student, Department of Civil Engineering, Southern Illinois University Carbondale Carbondale, Illinois, 62901-6603 2 Professor, Department of Civil Engineering, Southern Illinois University Carbondale Carbondale, Illinois, 62901-6603

  18. Engineering photochemical smog through convection towers

    SciTech Connect

    Elliott, S.; Prueitt, M.L.; Bossert, J.E.; Mroz, E.J.; Krakowski, R.A.; Miller, R.L.; Jacobson, M.Z.; Turco, R.P. |

    1995-02-01

    Reverse convection towers have attracted attention as a medium for cleansing modern cities. Evaporation of an aqueous mist injected at the tower opening could generate electrical power by creating descent, and simultaneously scavenge unsightly and unhealthful particulates. The study offered here assesses the influence to tower water droplets on the photochemical component of Los Angeles type smog. The primary radical chain initiator OH is likely removed into aqueous phases well within the residence time of air in the tower, and then reacts away rapidly. Organics do not dissolve, but nighttime hydrolysis of N{sub 2}O{sub 5} depletes the nitrogen oxides. A lack of HOx would slow hydrocarbon oxidation and so also ozone production. Lowering of NOx would also alter ozone production rates, but the direction is uncertain. SO{sub 2} is available in sufficient quantities in some urban areas to react with stable oxidants, and if seawater were the source of the mist, the high pH would lead to fast sulfur oxidation kinetics. With an accommodation coefficient of 10{sup {minus}3}, however, ozone may not enter the aqueous phase efficiently. Even if ozone is destroyed or its production suppressed, photochemical recovery times are on the order of hours, so that tower processing must be centered on a narrow midday time window. The cost of building the number of structures necessary for this brief turnover could be prohibitive. The increase in humidity accompanying mist evaporation could be controlled with condensers, but might otherwise counteract visibility enhancements by recreating aqueous aerosols. Quantification of the divergent forcings convection towers must exert upon the cityscape would call for coupled three dimensional modeling of transport, microphysics, and photochemistry. 112 refs.

  19. Tropospheric Ozone and Photochemical Smog

    NASA Astrophysics Data System (ADS)

    Sillman, S.

    2003-12-01

    The question of air quality in polluted regions represents one of the issues of geochemistry with direct implications for human well-being. Human health and well-being, along with the well-being of plants, animals, and agricultural crops, are dependent on the quality of air we breathe. Since the start of the industrial era, air quality has become a matter of major importance, especially in large cities or urbanized regions with heavy automobile traffic and industrial activity.Concern over air quality existed as far back as the 1600s. Originally, polluted air in cities resulted from the burning of wood or coal, largely as a source of heat. The industrial revolution in England saw a great increase in the use of coal in rapidly growing cities, both for industrial use and domestic heating. London suffered from devastating pollution events during the late 1800s and early 1900s, with thousands of excess deaths attributed to air pollution (Brimblecombe, 1987). With increasing use of coal, other instances also occurred in continental Europe and the USA. These events were caused by directly emitted pollutants (primary pollutants), including sulfur dioxide (SO2), carbon monoxide (CO), and particulates. They were especially acute in cities with northerly locations during fall and winter when sunlight is at a minimum. These original pollution events gave rise to the term "smog" (a combination of smoke and fog). Events of this type have become much less severe since the 1950s in Western Europe and the US, as natural gas replaced coal as the primary source of home heating, industrial smokestacks were designed to emit at higher altitudes (where dispersion is more rapid), and industries were required to install pollution control equipment.Beginning in the 1950s, a new type of pollution, photochemical smog, became a major concern. Photochemical smog consists of ozone (O3) and other closely related species ("secondary pollutants") that are produced photochemically from directly

  20. Outstanding Phenotypic Differences in the Profile of Amyloid-β between Tg2576 and APPswe/PS1dE9 Transgenic Mouse Models of Alzheimer’s Disease

    PubMed Central

    Allué, José Antonio; Sarasa, Leticia; Izco, María; Pérez-Grijalba, Virginia; Fandos, Noelia; Pascual-Lucas, María; Ogueta, Samuel; Pesini, Pedro; Sarasa, Manuel

    2016-01-01

    APPswe/PS1dE9 and Tg2576 are very common transgenic mouse models of Alzheimer’s disease (AD), used in many laboratories as tools to research the mechanistic process leading to the disease. In order to augment our knowledge about the amyloid-β (Aβ) isoforms present in both transgenic mouse models, we have developed two chromatographic methods, one acidic and the other basic, for the characterization of the Aβ species produced in the brains of the two transgenic mouse models. After immunoprecipitation and micro-liquid chromatography-electrospray ionization mass spectrometry/mass spectrometry, 10 species of Aβ, surprisingly all of human origin, were detected in the brain of Tg2576 mouse, whereas 39 species, of both murine and human origin, were detected in the brain of the APP/PS1 mouse. To the best of our knowledge, this is the first study showing the identification of such a high number of Aβ species in the brain of the APP/PS1 transgenic mouse, whereas, in contrast, a much lower number of Aβ species were identified in the Tg2576 mouse. Therefore, this study brings to light a relevant phenotypic difference between these two popular mice models of AD. PMID:27258422

  1. Effects of alkoxy groups on arene rings of lignin β-O-4 model compounds on the efficiencies of single electron transfer-promoted photochemical and enzymatic C-C Bond Cleavage Reactions.

    PubMed

    Lim, Suk Hyun; Nahm, Keepyung; Ra, Choon Sup; Cho, Dae Won; Yoon, Ung Chan; Latham, John A; Dunaway-Mariano, Debra; Mariano, Patrick S

    2013-09-20

    To gain information about how alkoxy substitution in arene rings of β-O-4 structural units within lignin governs the efficiencies/rates of radical cation C1-C2 bond cleavage reactions, single electron transfer (SET) photochemical and lignin peroxidase-catalyzed oxidation reactions of dimeric/tetrameric model compounds have been explored. The results show that the radical cations derived from less alkoxy-substituted dimeric β-O-4 models undergo more rapid C1-C2 bond cleavage than those of more alkoxy-substituted analogues. These findings gained support from the results of DFT calculations, which demonstrate that C1-C2 bond dissociation energies of β-O-4 radical cations decrease as the degree of alkoxy substitution decreases. In SET reactions of tetrameric compounds consisting of two β-O-4 units, containing different degrees of alkoxy substitution, regioselective radical cation C-C bond cleavage was observed to occur in one case at the C1-C2 bond in the less alkoxy-substituted β-O-4 moiety. However, regioselective C1-C2 cleavage in the more alkoxy-substituted β-O-4 moiety was observed in another case, suggesting that other factors might participate in controlling this process. These observations show that lignins containing greater proportions of less rather than more alkoxylated rings as part of β-O-4 units would be more efficiently cleaved by SET mechanisms.

  2. Photochemical conversion of solar energy.

    PubMed

    Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

    2008-01-01

    Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago.

  3. Photochemical "triode" molecular signal transducer.

    PubMed

    Keirstead, Amy E; Bridgewater, James W; Terazono, Yuichi; Kodis, Gerdenis; Straight, Stephen; Liddell, Paul A; Moore, Ana L; Moore, Thomas A; Gust, Devens

    2010-05-12

    A molecular "hexad" in which five bis(phenylethynyl)anthracene (BPEA) fluorophores and a dithienylethene photochrome are organized by a central hexaphenylbenzene unit has been prepared. Singlet-singlet energy transfer among the BPEA units occurs on the 0.4 and 60 ps time scales, and when the dithienylethene is in the open form, the BPEA units fluoresce in the 515 nm region with a quantum yield near unity. When the dithienylethene is photoisomerized by UV light to the closed form, which absorbs in the 500-700 nm region, the closed isomer strongly quenches all of the excited singlet states of BPEA via energy transfer, causing the fluorescence quantum yield to drop to near zero. This photochemical behavior permits the hexad to function in a manner analogous to a triode vacuum tube or transistor. When a solution of the hexad is irradiated with steady-state light at 350 nm and with red light (>610 nm) of modulated intensity, the BPEA fluorescence excited by the 350 nm light is modulated accordingly. The fluorescence corresponds to the output of a triode tube or transistor and the modulated red light to the grid signal of the tube or gate voltage of the transistor. Frequency modulation, amplitude modulation, and phase modulation are all observed. The unusual ability to modulate intense, shorter-wavelength fluorescence with longer-wavelength light could be useful for the detection of fluorescence from probe molecules without interference from other emitters in biomolecular or nanotechnological applications.

  4. Linear stability of free planetary waves in the presence of radiative-photochemical feedbacks

    NASA Technical Reports Server (NTRS)

    Nathan, Terrence R.; Li, Long

    1991-01-01

    The diabatic effects of Newtonian cooling and ozone-dynamics interaction on the linear stability of free planetary waves in the atmosphere have been studied using a simple beta-plane model. The model couples radiative transfer, ozone advection, and ozone photochemistry with the quasi-geostrophic dynamical circulation. An analytical expression is derived which demonstrates the following: (1) the influence of meridional ozone advection on wave growth or decay depends on the wave and basic state vertical structures; and (2) photochemically accelerated cooling, which predominates in the upper stratosphere, augments the Newtonian cooling rate and is stabilizing. Attention is also given to the 1D linear stability problem which is numerically solved for a Charney basic state and for zonal mean basic states. It is shown that ozone heating generated by ozone-dynamics interaction in the stratosphere can reduce (enhance) the damping rates due to Newtonian cooling by as much as 50 percent for planetary waves of large vertical scale and maximum amplitude in the stratosphere.

  5. Explicit photochemical mechanism for atmospheric oxidation of n-butane

    SciTech Connect

    Wen, L.

    1992-01-01

    Alkanes, being an important component of atmosphere, serve as precursors to ozone formation in urban and rural air masses. An explicit photochemical oxidation mechanism for n-butane, which is the major hydrocarbon component of automobile exhaust, is created in this work. The yields of organic nitrates from n-butane, n-pentane, and methyl ethyl ketone photooxidations were studied in Teflon bag and smog chamber experiments. Comparing with the expression currently using the most atmospheric model studies, the total butyl nitrates yield obtained in this work is about 36% lower, and the ratio of primary to secondary butyl nitrates is slightly higher. It is shown in this work that the yields of hydroxyl and carbonyl butyl nitrates are very low, and can be ignored in the explicit photochemical mechanisms. The explicit photochemical oxidation mechanism for methyl ethyl ketone (MEK) was created first because it is the major product from photooxidation of n-butane. The explicit photochemical oxidation mechanism for n-butane, created later, draws on the MEK mechanism. The mechanisms were tested by comparing model predictions with experimental observations from smog chamber experiments. The comparisons were conducted for species which had experimental observation data, such as O[sub 3], NO, and NO[sub 2], n-butane, MEK, organic nitrates, and aldehydes species. The sixteen smog chamber experiments, used in model simulations, were conducted during 1978 to 1992. The mechanisms are mainly based on the available kinetic data in literature and the experimental result in this work. The rate constants for some reactions in the mechanisms were adjusted to make a better fit with the experimental observations. These reactions were: reaction of OH and n-butane to form secondary butyl peroxy radical, decomposition of secondary butoxy radical, and reaction of OH and MEK.

  6. Thermal and photochemical crosslinking of hyperbranched polyphenylene with organic azides.

    PubMed

    Pötzsch, Robert; Voit, Brigitte

    2012-04-23

    Here, we report on the first example of crosslinking (CL) hyperbranched polyphenylene (hb-PPh) with a small molecule crosslinker 1,3,5-tris(azidomethyl)benzene (TAMB). It was successfully shown that CL of the hb-PPh/TAMB (9:1) film is possible either thermally or photochemically making use of fundamentally different reaction mechanisms. Starting from a model reaction to prove the feasibility of the thermal CL reaction, we went on to check both the thermal and the photochemical crosslinkability of micrometer thick films. IR spectroscopy was furthermore used to confirm the CL process. Finally, the thin film morphology of the films before and after CL was investigated by AFM, revealing that the surface morphology was unaffected by the CL processes.

  7. Contributions of biogenic and anthropogenic hydrocarbons to photochemical smog formation

    SciTech Connect

    Paulson, S.E.

    1991-01-01

    Photochemical oxidation of biogenic (Isoprene) and anthropogenic (1-octene) hydrocarbons are examined. Experiments studied the individual daylight reactions of both isoprene and 1-octene, including those of OH, O{sub 3}, O({sup 3}P), and NO{sub 2}. The O{sub 3} reactions are found to produce significant quantities of OH, O({sup 3}P), and carbonyl yields that total about 100%. Isomerization is found to be an important channel for both isoprene and 1-octene. O({sup 3}P) reactions are found to have relatively minor decomposition pathways, resulting instead in epoxide formation. Results from both the smog chamber experiments and computer kinetic modeling were then used to develop photochemical oxidation mechanisms for each hydrocarbon. Aerosol formed by isoprene and another biogenic, {beta}-pinene, are characterized.

  8. Photochemical oxidants: state of the science.

    PubMed

    Kley, D; Kleinmann, M; Sanderman, H; Krupa, S

    1999-01-01

    Atmospheric photochemical processes resulting in the production of tropospheric ozone (O(3)) and other oxidants are described. The spatial and temporal variabilities in the occurrence of surface level oxidants and their relationships to air pollution meteorology are discussed. Models of photooxidant formation are reviewed in the context of control strategies and comparisons are provided of the air concentrations of O(3) at select geographic locations around the world. This overall oxidant (O(3)) climatology is coupled to human health and ecological effects. The discussion of the effects includes both acute and chronic responses, mechanisms of action, human epidemiological and plant population studies and briefly, efforts to establish cause-effect relationships through numerical modeling. A short synopsis is provided of the interactive effects of O(3) with other abiotic and biotic factors. The overall emphasis of the paper is on identifying the current uncertainties and gaps in our understanding of the state of the science and some suggestions as to how they may be addressed.

  9. PC-1D installation manual and user's guide

    SciTech Connect

    Basore, P.A.

    1991-05-01

    PC-1D is a software package for personal computers that uses finite-element analysis to solve the fully-coupled two-carrier semiconductor transport equations in one dimension. This program is particularly useful for analyzing the performance of optoelectronic devices such as solar cells, but can be applied to any bipolar device whose carrier flows are primarily one-dimensional. This User's Guide provides the information necessary to install PC-1D, define a problem for solution, solve the problem, and examine the results. Example problems are presented which illustrate these steps. The physical models and numerical methods utilized are presented in detail. This document supports version 3.1 of PC-1D, which incorporates faster numerical algorithms with better convergence properties than previous versions of the program. 51 refs., 17 figs., 5 tabs.

  10. Heat Capacity of 1D Molecular Chains

    NASA Astrophysics Data System (ADS)

    Bagatskii, M. I.; Barabashko, M. S.; Sumarokov, V. V.; Jeżowski, A.; Stachowiak, P.

    2017-04-01

    The heat capacity of 1D chains of nitrogen and methane molecules (adsorbed in the outer grooves of bundles of closed-cap single-walled carbon nanotubes) has been studied in the temperature ranges 2-40 and 2-60 K, respectively. The temperature dependence of the heat capacity of 1D chains of nitrogen molecules below 3 K is close to a linear. It was found that the rotational heat capacity of methane molecules is a significant part of the total heat capacity of the chains throughout the whole investigated temperature range, whereas in the case of nitrogen, the librations are significant only above 15 K. The dependence of the heat capacity for methane below 10 K indicates the presence of a Schottky anomaly caused by the tunneling between the lowest energy levels of the CH4 molecule rotational spectra. Characteristic features observed in the temperature dependence of the heat capacity of 1D methane crystals are also discussed.

  11. Upstream Design and 1D-CAE

    NASA Astrophysics Data System (ADS)

    Sawada, Hiroyuki

    Recently, engineering design environment of Japan is changing variously. Manufacturing companies are being challenged to design and bring out products that meet the diverse demands of customers and are competitive against those produced by rising countries(1). In order to keep and strengthen the competitiveness of Japanese companies, it is necessary to create new added values as well as conventional ones. It is well known that design at the early stages has a great influence on the final design solution. Therefore, design support tools for the upstream design is necessary for creating new added values. We have established a research society for 1D-CAE (1 Dimensional Computer Aided Engineering)(2), which is a general term for idea, methodology and tools applicable for the upstream design support, and discuss the concept and definition of 1D-CAE. This paper reports our discussion about 1D-CAE.

  12. The STEM-II regional scale acid deposition and photochemical oxidant model—I. An overview of model development and applications

    NASA Astrophysics Data System (ADS)

    Carmichael, Gregory R.; Peters, Leonard K.; Saylor, Rick D.

    The STEM-II pollutant transport/transformation/removal model has been enhanced to include scavenging by clouds and precipitation. The Advanced Scavenging Model (ASM) and Reactive Scavenging Model (RSM) have been coupled to STEM-II to enable comprehensive simulation and diagnosis analysis of field experiments designed to study acid deposition. In this paper, the STEM-II/ASM/RSM model is described. The coupled model is being used to analyze the PRECP-I field studies on an urban/suburban scale (Philadelphia), mesoscale (lower Ohio River Valley), and regional scale (eastern U.S.). The time period selected for detailed simulations and analysis is 29 April-5 May 1985. Subsequent papers will detail the results of these simulations.

  13. Modeling the photochemical attenuation of down-the-drain chemicals during river transport by stochastic methods and field measurements of pharmaceuticals and personal care products.

    PubMed

    Hanamoto, Seiya; Nakada, Norihide; Yamashita, Naoyuki; Tanaka, Hiroaki

    2013-01-01

    Existing stochastic models for predicting concentrations of down-the-drain chemicals in aquatic environments do not account for the diurnal variation of direct photolysis by sunlight, despite its being an important factor in natural attenuation. To overcome this limitation, we developed a stochastic model incorporating temporal variations in direct photolysis. To verify the model, we measured 57 pharmaceuticals and personal care products (PPCPs) in a 7.6-km stretch of an urban river, and determined their physical and biological properties in laboratory experiments. During transport along the river, 8 PPCPs, including ketoprofen and azithromycin, were attenuated by >20%, mainly owing to direct photolysis and adsorption to sediments. The photolabile PPCPs attenuated significantly in the daytime but persisted in the nighttime. The observations were similar to the values predicted by the photolysis model for the photolabile PPCPs (i.e., ketoprofen, diclofenac and furosemide) but not by the existing model. The stochastic model developed in this study was suggested to be a novel and useful stochastic model for evaluating direct photolysis of down-the-drain chemicals, which occurs during the river transport.

  14. Seasonal Photochemical Transformations of Nitrogen Species in a Forest Stream and Lake

    PubMed Central

    Porcal, Petr; Kopáček, Jiří; Tomková, Iva

    2014-01-01

    The photochemical release of inorganic nitrogen from dissolved organic matter is an important source of bio-available nitrogen (N) in N-limited aquatic ecosystems. We conducted photochemical experiments and used mathematical models based on pseudo-first-order reaction kinetics to quantify the photochemical transformations of individual N species and their seasonal effects on N cycling in a mountain forest stream and lake (Plešné Lake, Czech Republic). Results from laboratory experiments on photochemical changes in N speciation were compared to measured lake N budgets. Concentrations of organic nitrogen (Norg; 40–58 µmol L−1) decreased from 3 to 26% during 48-hour laboratory irradiation (an equivalent of 4–5 days of natural solar insolation) due to photochemical mineralization to ammonium (NH4+) and other N forms (Nx; possibly N oxides and N2). In addition to Norg mineralization, Nx also originated from photochemical nitrate (NO3−) reduction. Laboratory exposure of a first-order forest stream water samples showed a high amount of seasonality, with the maximum rates of Norg mineralization and NH4+ production in winter and spring, and the maximum NO3− reduction occurring in summer. These photochemical changes could have an ecologically significant effect on NH4+ concentrations in streams (doubling their terrestrial fluxes from soils) and on concentrations of dissolved Norg in the lake. In contrast, photochemical reactions reduced NO3− fluxes by a negligible (<1%) amount and had a negligible effect on the aquatic cycle of this N form. PMID:25551441

  15. Development of a speciated, hourly, and gridded air pollutants emission modeling system--a case study on the precursors of photochemical smog in the Seoul metropolitan area, Korea.

    PubMed

    Kim, D Y; Kim, J W

    2000-03-01

    A speciated, hourly, and gridded air pollutants emission modeling system (SHEMS) was developed and applied in predicting hourly nitrogen dioxide (NO2) and ozone (O3) levels in the Seoul Metropolitan Area (SMA). The primary goal of the SHEMS was to produce a systemized emission inventory for air pollutants including ozone precursors for modeling air quality in urban areas. The SHEMS is principally composed of three parts: (1) a pre-processor to process emission factors, activity levels, and spatial and temporal information using a geographical information system; (2) an emission model for each source type; and (3) a post-processor to produce report and input data for air quality models through database modeling. The source categories in SHEMS are point, area, mobile, natural, and other sources such as fugitive emissions. The emission database produced by SHEMS contains 22 inventoried compounds: sulfur dioxide, NO2, carbon monoxide, and 19 speciated volatile organic compounds. To validate SHEMS, the emission data were tested with the Urban Airshed Model to predict NO2 and O3 concentrations in the SMA during selected episode days in 1994. The results turned out to be reliable in describing temporal variation and spatial distribution of those pollutants.

  16. Suppressing photochemical reactions with quantized light fields

    NASA Astrophysics Data System (ADS)

    Galego, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes

    2016-12-01

    Photoisomerization, that is, a photochemical reaction leading to a change of molecular structure after absorption of a photon, can have detrimental effects such as leading to DNA damage under solar irradiation, or as a limiting factor for the efficiency of solar cells. Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, as well as other photochemical reactions, and thus convert molecules that normally show fast photodegradation into photostable forms. We find this to be especially efficient in the case of collective strong coupling, where the distribution of a single excitation over many molecules and the light mode leads to a collective protection effect that almost completely suppresses the photochemical reaction.

  17. Suppressing photochemical reactions with quantized light fields

    PubMed Central

    Galego, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes

    2016-01-01

    Photoisomerization, that is, a photochemical reaction leading to a change of molecular structure after absorption of a photon, can have detrimental effects such as leading to DNA damage under solar irradiation, or as a limiting factor for the efficiency of solar cells. Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, as well as other photochemical reactions, and thus convert molecules that normally show fast photodegradation into photostable forms. We find this to be especially efficient in the case of collective strong coupling, where the distribution of a single excitation over many molecules and the light mode leads to a collective protection effect that almost completely suppresses the photochemical reaction. PMID:27941754

  18. Contribution of regional-scale fire events to ozone and PM2.5 air quality estimated by photochemical modeling approaches

    EPA Science Inventory

    Two specific fires from 2011 are tracked for local to regional scale contribution to ozone (O3) and fine particulate matter (PM2.5) using a freely available regulatory modeling system that includes the BlueSky wildland fire emissions tool, Spare Matrix Operator Kernel Emissions (...

  19. Formation and inhibition of photochemical smog

    SciTech Connect

    Heicklen, J.

    1987-01-01

    Photochemical smog is caused by a free-radical chain mechanism which converts NO to NO/sub 2/. The NO/sub 2/ further reacts to produce ozone, nitric acid, and peracylnitrates. This chain mechanism can be inhibited by suitable free-radical scavengers. The chemistry and toxicology of one such free-radical scavenger, diethylhydroxylamine, has been studied in depth. It has been shown to be effective, safe, and practical for use in urban atmospheres to prevent photochemical smog formation. 42 references.

  20. Photochemical model evaluation of the ground-level ozone impacts on ambient air quality and vegetation health in the Alberta oil sands region: Using present and future emission scenarios

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, Krish; Cho, Sunny; Morris, Ralph; Spink, David; Jung, Jaegun; Pauls, Ron; Duffett, Katherine

    2016-09-01

    One of the potential environmental issues associated with oil sands development is increased ozone formation resulting from NOX and volatile organic compound emissions from bitumen extraction, processing and upgrading. To manage this issue in the Athabasca Oil Sands Region (AOSR) in northeast Alberta, a regional multi-stakeholder group, the Cumulative Environmental Management Association (CEMA), developed an Ozone Management Framework that includes a modelling based assessment component. In this paper, we describe how the Community Multi-scale Air Quality (CMAQ) model was applied to assess potential ground-level ozone formation and impacts on ambient air quality and vegetation health for three different ozone precursor cases in the AOSR. Statistical analysis methods were applied, and the CMAQ performance results met the U.S. EPA model performance goal at all sites. The modelled 4th highest daily maximum 8-h average ozone concentrations in the base and two future year scenarios did not exceed the Canada-wide standard of 65 ppb or the newer Canadian Ambient Air Quality Standards of 63 ppb in 2015 and 62 ppb in 2020. Modelled maximum 1-h ozone concentrations in the study were well below the Alberta Ambient Air Quality Objective of 82 ppb in all three cases. Several ozone vegetation exposure metrics were also evaluated to investigate the potential impact of ground-level ozone on vegetation. The chronic 3-months SUM60 exposure metric is within the CEMA baseline range (0-2000 ppb-hr) everywhere in the AOSR. The AOT40 ozone exposure metric predicted by CMAQ did not exceed the United Nations Economic Commission for Europe (UN/ECE) threshold of concern of 3000 ppb-hr in any of the cases but is just below the threshold in high-end future emissions scenario. In all three emission scenarios, the CMAQ predicted W126 ozone exposure metric is within the CEMA baseline threshold of 4000 ppb-hr. This study outlines the use of photochemical modelling of the impact of an industry (oil

  1. Do Photochemical Hazes Cloud the Atmosphere of 51 Eri b?

    NASA Astrophysics Data System (ADS)

    Marley, Mark; Zahnle, Kevin; Moses, Julianne; Morley, Caroline

    2015-12-01

    The first young giant planet to be discovered by the Gemini Planet Imager was the ~ 2MJ planet 51 Eri b. This ~20 Myr old young Jupiter is the first directly imaged planet to show unmistakable methane in H band. To constrain the planet’s mass, atmospheric temperature, and composition, the GPI J and H band spectra as well as some limited photometric points were compared to the predictions of substellar atmosphere models. The best fitting models reported in the discovery paper (Macintosh et al. 2015) relied upon a combination of clear and cloudy atmospheric columns to reproduce the data. In the atmosphere of an object as cool as 700 K the global silicate and iron clouds would be expected to be found well below the photosphere, although strong vertical mixing in the low gravity atmosphere is a possibility. Instead, clouds of Na2S, as have been detected in brown dwarf atmospheres, are a likely source of particle opacity. As a third explanation we have explored whether atmospheric photochemistry, driven by the UV flux from the primary star, may yield hazes that also influence the observed spectrum of the planet. To explore this possibility we have modeled the atmospheric photochemistry of 51 Eri b using two state-of-the-art photochemical models, both capable of predicting yields of complex hydrocarbons under various atmospheric conditions. We also have explored whether photochemical products can alter the equilibrium temperature profile of the atmosphere. In our presentation we will summarize the modeling approach employed to characterize 51 Eri b, explaining constraints on the planet’s effective temperature, gravity, and atmospheric composition and also present results of our studies of atmospheric photochemistry. We will discuss whether photochemical hazes could indeed be responsible for the particulate opacity that apparently sculpts the spectrum of the planet.

  2. Diagnosis of Photochemical Ozone Production Rates and Limiting Factors based on Observation-based Modeling Approach over East Asia: Impact of Radical Chemistry Mechanism and Ozone-Control Implications

    NASA Astrophysics Data System (ADS)

    Kanaya, Y.

    2015-12-01

    Growth of tropospheric ozone, causing health and climate impacts, is concerned over East Asia, because emissions of precursors have dramatically increased. Photochemical production rates of ozone and limiting factors, primarily studied for urban locations, have been poorly assessed within a perspective of regional-scale air pollution over East Asia. We performed comprehensive observations of ozone precursors at several locations with regional representativeness and made such assessment based on the observation-based modeling approach. Here, diagnosis at Fukue Island (32.75°N, 128.68°E) remotely located in western Japan (May 2009) is highlighted, where the highest 10% of hourly ozone concentrations reached 72‒118 ppb during May influenced by Asian continental outflow. The average in-situ ozone production rate was estimated to be 6.8 ppb per day, suggesting that in-travel production was still active, while larger buildup must have occurred beforehand. Information on the chemical status of the air mass arriving in Japan is important, because it affects how further ozone production occurs after precursor addition from Japanese domestic emissions. The main limiting factor of ozone production was usually NOx, suggesting that domestic NOx emission control is important in reducing further ozone production and the incidence of warning issuance (>120 ppb). VOCs also increased the ozone production rate, and occasionally (14% of time) became dominant. This analysis implies that the VOC reduction legislation recently enacted should be effective. The uncertainty in the radical chemistry mechanism governing ozone production had a non-negligible impact, but the main conclusion relevant to policy was not altered. When chain termination was augmented by HO2-H2O + NO/NO2 reactions and by heterogeneous loss of HO2 on aerosol particle surfaces, the daily ozone production rate decreased by <24%, and the fraction of hours when the VOC-limited condition occurred varied from 14% to 13

  3. On the origin of the ionosphere at Moon : a study using results from Chandrayaan-I S-band radio occultation experiment and a photochemical model

    NASA Astrophysics Data System (ADS)

    Kailasam Madathil, Ambili; Bhardwaj, Anil; Choudhary, Raj Kumar

    2016-07-01

    Using Chandrayaan-1 communication link between orbiter and ground (S-band frequency), the presence of ionosphere at Moon has been explored using Radio Occultation technique. Results obtained from the observations conducted between July 30 and August 14, 2009 show evidence for a possible existence of the Ionosphere at Moon. A few seconds before the occultation of Chandrayaan-1 radio signals, extra fluctuation in the rate of change of difference between the theoretically estimated Doppler and observed Doppler was observed. The fluctuation was more pronounced when the probing radio waves were crossing through the day-night terminator. Using standard onion-peeling technique to invert the phase changes in radio signals to the refractivity of the medium, we estimated the bending angle and hence the electron density profiles for the Lunar medium. The estimated electron density near the Lunar surface was of the order of 400 - 1000 cm ^{-3} which decreased monotonically with increasing altitude till about 40 km above the surface where it became negligible. The observed electron density was compared with the results from a model which was developed based on CHACE measurements abroad Moon Impact Probe of Chandrayaan-I. The model included the photo chemical reactions and solar wind interactions of the lunar plasma. We propose that the ionosphere over Moon could have molecular origin with H _{2}O ^{+},CO_{2} ^{+} and H_{3}O ^{+} as dominant ions.

  4. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati...

  5. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati...

  6. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati...

  7. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati...

  8. 40 CFR 52.1877 - Control strategy: Photochemical oxidants (hydrocarbons).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... oxidants (hydrocarbons). 52.1877 Section 52.1877 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1877 Control strategy: Photochemical oxidants (hydrocarbons). (a) The requirements of Subpart G of this... national standard for photochemical oxidants (hydrocarbons) in the Metropolitan Cincinnati...

  9. A Simple Parallel Photochemical Reactor for Photodecomposition Studies

    ERIC Educational Resources Information Center

    Xiaobo Chen; Halasz, Sarah M.; Giles, Eric C.; Mankus, Jessica V.; Johnson, Joseph C.; Burda, Clemens

    2006-01-01

    A simple and useful parallel photochemical reactor intended to study the photodecomposition of dyes using semiconductor photocatalysis is presented. The photochemical reactions are followed through time-dependent changes in the ground-state absorption spectra of the dyes.

  10. Glass-based 1-D dielectric microcavities

    NASA Astrophysics Data System (ADS)

    Chiasera, Alessandro; Scotognella, Francesco; Valligatla, Sreeramulu; Varas, Stefano; Jasieniak, Jacek; Criante, Luigino; Lukowiak, Anna; Ristic, Davor; Gonçalves, Rogeria Rocha; Taccheo, Stefano; Ivanda, Mile; Righini, Giancarlo C.; Ramponi, Roberta; Martucci, Alessandro; Ferrari, Maurizio

    2016-11-01

    We have developed a reliable RF sputtering techniques allowing to fabricate glass-based one dimensional microcavities, with high quality factor. This property is strongly related to the modification of the density of states due to the confinement of the gain medium in a photonic band gap structure. In this short review we present some of the more recent results obtained by our team exploiting these 1D microcavities. In particular we present: (1) Er3+ luminescence enhancement of the 4I13/2 → 4I15/2 transition; (2) broad band filters based on disordered 1-D photonic structures; (3) threshold defect-mode lasing action in a hybrid structure.

  11. Centrosome Positioning in 1D Cell Migration

    NASA Astrophysics Data System (ADS)

    Adlerz, Katrina; Aranda-Espinoza, Helim

    During cell migration, the positioning of the centrosome and nucleus define a cell's polarity. For a cell migrating on a two-dimensional substrate the centrosome is positioned in front of the nucleus. Under one-dimensional confinement, however, the centrosome is positioned behind the nucleus in 60% of cells. It is known that the centrosome is positioned by CDC42 and dynein for cells moving on a 2D substrate in a wound-healing assay. It is currently unknown, however, if this is also true for cells moving under 1D confinement, where the centrosome position is often reversed. Therefore, centrosome positioning was studied in cells migrating under 1D confinement, which mimics cells migrating through 3D matrices. 3 to 5 μm fibronectin lines were stamped onto a glass substrate and cells with fluorescently labeled nuclei and centrosomes migrated on the lines. Our results show that when a cell changes directions the centrosome position is maintained. That is, when the centrosome is between the nucleus and the cell's trailing edge and the cell changes direction, the centrosome will be translocated across the nucleus to the back of the cell again. A dynein inhibitor did have an influence on centrosome positioning in 1D migration and change of directions.

  12. Vulnerability of calbindin, calretinin and parvalbumin in a transgenic/knock-in APPswe/PS1dE9 mouse model of Alzheimer disease together with disruption of hippocampal neurogenesis.

    PubMed

    Verdaguer, Ester; Brox, Susana; Petrov, Dmitry; Olloquequi, Jordi; Romero, Rafael; de Lemos, M Luisa; Camins, Antoni; Auladell, Carme

    2015-09-01

    The pathogenesis of Alzheimer disease (AD) is characterized by accumulation of β-amyloid protein in the brain (in both soluble and insoluble forms) and by the presence of intracellular neurofibrillary tangles (NFTs), leading to neurotoxicity. The exact mechanisms whereby Aβ triggers brain alterations are unclear. However, accumulating evidence suggests that a deregulation of Ca(2+) signaling may play a major role in disease progression. Calcium-buffering proteins, including calbindin-D28K (CB), calretinin (CR) and parvalbumin (PV), may offer neuroprotection by maintaining calcium homeostasis. Although marked reductions in these proteins have been observed in the brains of mice and humans with AD, their contribution to AD pathology remains unclear. The aim of the present study was to analyze distribution patterns of CB(+,) CR(+) and PV(+) interneurons in different areas of the hippocampus, a brain region that is severely affected in AD. A transgenic knock-in APPswe/PS1dE9 mouse model of familial AD was used. The data were obtained from the brains of 3- and 12-month-old animals. These ages roughly correspond to an early mature adult (prior to clinical manifestations) and a late middle-age (clinical symptoms readily detectable) phase in human AD patients. Immunostaining revealed increases in CB and PV immunoreactivity (IR) in the hippocampus of 3-month-old transgenic mice, compared to wild-type animals. Possibly, these proteins are upregulated in an attempt to control cellular homeostasis and synaptic plasticity. However, the pattern of CB-IR was reversed in 12-month-old animals, potentially indicating a loss of cellular capacity to respond to pathophysiological processes. In addition, at this age, a noticeable increase in PV-IR was observed, suggesting the presence of hippocampal network hyperactivity in older AD-like mice. Our results indicate that CaBP(+) neuronal subpopulations play a role in adult neurogenesis and in AD pathology, particularly at early disease

  13. Photochemical Transformation of Graphene Oxide in Sunlight

    EPA Science Inventory

    Graphene oxide (GO) is a graphene derivative that is more easily manufactured in large scale and used to synthesize reduced graphene oxide (rGO) with properties analogous to graphene. In this study, we investigate the photochemical fate of GO under sunlight conditions. The resu...

  14. Enhanced aqueous photochemical reaction rates after freezing.

    PubMed

    Grannas, Amanda M; Bausch, Alexandra R; Mahanna, Kendell M

    2007-11-01

    Sunlit snow/ice is known to play an important role in the processing of atmospheric species, including photochemical production of NO(x), HONO, molecular halogens, alkyl halides, and carbonyl compounds, among others. It has been shown that a liquid-like (quasi-liquid or disordered) layer exists on the surface of pure ice and that this quasi-liquid layer is also found on the surface of ambient snow crystals and ice at temperatures similar to polar conditions. However, it is unclear what role the liquid-like fractions present in and on frozen water play in potential photochemical reactions, particularly with regard to organic substrates. Here, we report a detailed study of enhanced rates of photochemical nucleophilic substitution of p-nitroanisole (PNA) with pyridine, a well-characterized and commonly used actinometer system. Reaction rates were enhanced by a factor of up to approximately 40 when frozen at temperatures between 236 and 272 K. Reaction rates were dependent on temperature and solute concentration, both variables that control the nature of the liquid-like fraction in frozen water. The results obtained indicate that a major portion of the organic solutes is excluded to the liquid-like layer, significantly impacting the rate of the photochemical nucleophilic substitution reaction studied here. Also, the direct comparison of liquid-phase kinetics to reactions occurring in frozen water systems is drawn into question, indicating that a simple extrapolation of liquid-phase mechanisms to snow/ice may not be valid for certain reactions.

  15. Additive and Photochemical Manufacturing of Copper

    NASA Astrophysics Data System (ADS)

    Yung, Winco K. C.; Sun, Bo; Meng, Zhengong; Huang, Junfeng; Jin, Yingdi; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-12-01

    In recent years, 3D printing technologies have been extensively developed, enabling rapid prototyping from a conceptual design to an actual product. However, additive manufacturing of metals in the existing technologies is still cost-intensive and time-consuming. Herein a novel platform for low-cost additive manufacturing is introduced by simultaneously combining the laser-induced forward transfer (LIFT) method with photochemical reaction. Using acrylonitrile butadiene styrene (ABS) polymer as the sacrificial layer, sufficient ejection momentum can be generated in the LIFT method. A low-cost continuous wave (CW) laser diode at 405 nm was utilized and proved to be able to transfer the photochemically synthesized copper onto the target substrate. The wavelength-dependent photochemical behaviour in the LIFT method was verified and characterized by both theoretical and experimental studies compared to 1064 nm fiber laser. The conductivity of the synthesized copper patterns could be enhanced using post electroless plating while retaining the designed pattern shapes. Prototypes of electronic circuits were accordingly built and demonstrated for powering up LEDs. Apart from pristine PDMS materials with low surface energies, the proposed method can simultaneously perform laser-induced forward transfer and photochemical synthesis of metals, starting from their metal oxide forms, onto various target substrates such as polyimide, glass and thermoplastics.

  16. Additive and Photochemical Manufacturing of Copper

    PubMed Central

    Yung, Winco K. C.; Sun, Bo; Meng, Zhengong; Huang, Junfeng; Jin, Yingdi; Choy, Hang Shan; Cai, Zhixiang; Li, Guijun; Ho, Cheuk Lam; Yang, Jinlong; Wong, Wai Yeung

    2016-01-01

    In recent years, 3D printing technologies have been extensively developed, enabling rapid prototyping from a conceptual design to an actual product. However, additive manufacturing of metals in the existing technologies is still cost-intensive and time-consuming. Herein a novel platform for low-cost additive manufacturing is introduced by simultaneously combining the laser-induced forward transfer (LIFT) method with photochemical reaction. Using acrylonitrile butadiene styrene (ABS) polymer as the sacrificial layer, sufficient ejection momentum can be generated in the LIFT method. A low-cost continuous wave (CW) laser diode at 405 nm was utilized and proved to be able to transfer the photochemically synthesized copper onto the target substrate. The wavelength-dependent photochemical behaviour in the LIFT method was verified and characterized by both theoretical and experimental studies compared to 1064 nm fiber laser. The conductivity of the synthesized copper patterns could be enhanced using post electroless plating while retaining the designed pattern shapes. Prototypes of electronic circuits were accordingly built and demonstrated for powering up LEDs. Apart from pristine PDMS materials with low surface energies, the proposed method can simultaneously perform laser-induced forward transfer and photochemical synthesis of metals, starting from their metal oxide forms, onto various target substrates such as polyimide, glass and thermoplastics. PMID:28000733