Bibliografie tematiche / Interface fluxes

Letteratura scientifica selezionata sul tema "Interface fluxes"

Autore: Grafiati

Pubblicato: 22 giugno 2024

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Articoli di riviste sul tema "Interface fluxes":

Li, Yuehua, e Trevor J. McDougall. "Double-Diffusive Interleaving: Properties of the Steady-State Solution". Journal of Physical Oceanography 45, n. 3 (marzo 2015): 813–35. http://dx.doi.org/10.1175/jpo-d-13-0236.1.

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AbstractDouble-diffusive interleaving is examined as it progresses from a linear instability toward finite amplitude. When the basic stratification is in the “finger” sense, the initial series of finger interfaces is unstable and one grows in strength at the expense of the others. At an intermediate stage of its development, the interleaving motions pass through a stage when every second interface in the vertical is stable to double diffusion. At a later time this interface turns into a “diffusive” double-diffusive interface. This study takes the fluxes of heat and salt across both the finger and diffusive interfaces to be given by the laboratory flux laws, and the authors ask whether a steady state is possible. It is found that the fluxes across the diffusive interfaces must be many times stronger relative to the corresponding fluxes across the finger interfaces than is indicated from existing flux expressions derived from laboratory experiments. The total effect of the interleaving motion on the vertical fluxes of heat and of salt are calculated for the steady-state solutions. It is found that both the fluxes of heat and salt are upgradient, corresponding to a negative vertical diffusion coefficient for all heat, salt, and density. For moderate to large Prandtl numbers, these negative effective diapycnal diffusivities of heat and salt are approximately equal so that the interleaving process acts to counteract some of the usual turbulent diapycnal diffusivity due to breaking internal waves.

Fleury, M., e R. G. Lueck. "Fluxes across a thermohaline interface". Deep Sea Research Part A. Oceanographic Research Papers 38, n. 7 (luglio 1991): 745–69. http://dx.doi.org/10.1016/0198-0149(91)90017-a.

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Yang, Li-Ming, Chang Shu, Wen-Ming Yang e Yan Wang. "Extension of lattice Boltzmann flux solver for simulation of compressible multi-component flows". Modern Physics Letters B 32, n. 12n13 (10 maggio 2018): 1840001. http://dx.doi.org/10.1142/s0217984918400018.

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The lattice Boltzmann flux solver (LBFS), which was presented by Shu and his coworkers for solving compressible fluid flow problems, is extended to simulate compressible multi-component flows in this work. To solve the two-phase gas–liquid problems, the model equations with stiffened gas equation of state are adopted. In this model, two additional non-conservative equations are introduced to represent the material interfaces, apart from the classical Euler equations. We first convert the interface equations into the full conservative form by applying the mass equation. After that, we calculate the numerical fluxes of the classical Euler equations by the existing LBFS and the numerical fluxes of the interface equations by the passive scalar approach. Once all the numerical fluxes at the cell interface are obtained, the conservative variables at cell centers can be updated by marching the equations in time and the material interfaces can be identified via the distributions of the additional variables. The numerical accuracy and stability of present scheme are validated by its application to several compressible multi-component fluid flow problems.

Käser, Martin, e Michael Dumbser. "A highly accurate discontinuous Galerkin method for complex interfaces between solids and moving fluids". GEOPHYSICS 73, n. 3 (maggio 2008): T23—T35. http://dx.doi.org/10.1190/1.2870081.

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We have extended a new highly accurate numerical scheme for unstructured 2D and 3D meshes based on the discontinuous Galerkin approach to simulate seismic wave propagation in heterogeneous media containing fluid-solid interfaces. Because of the formulation of the wave equations as a unified first-order hyperbolic system in velocity stress, the fluid can be in movement along the interface. The governing equations within the moving fluid are derived from well-known first principles in fluid mechanics. The discontinuous Galerkin approach allows for jumps of the material parameters and the solution across element interfaces, which are handled by Riemann solvers or numerical fluxes. The use of Riemann solvers at the element interfaces makesthe treatment of the fluid particularly simple bysetting the shearmodulus in the fluid region to zero. No additional compatibility relations, such as vanishing shear stress or continuity of normal stresses, are necessary to couple the solid and fluid along an interface. The Riemann solver automatically recognizes the jump of the material coefficients at the interface and provides the correct numerical fluxes for fluid-solid contacts. Therefore, wave propagation in the entire computational domain containing heterogeneous media, namely moving fluids and elastic solids, can be described by a uniform set of acoustic and elastic wave equations. The accuracy of the proposed scheme is confirmed by comparing numerical results against analytic solutions. The potential of the new method was demonstrated in a 3D model problem typical for marine seismic exploration with a fluid-solid interface determined by a complicated bathymetry.

GONZALEZ-JUEZ, ESTEBAN, ALAN R. KERSTEIN e DAVID O. LIGNELL. "Fluxes across double-diffusive interfaces: a one-dimensional-turbulence study". Journal of Fluid Mechanics 677 (12 aprile 2011): 218–54. http://dx.doi.org/10.1017/jfm.2011.78.

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This work is a parametric study of the fluxes of heat and salt across unsheared and sheared double-diffusive interfaces using one-dimensional-turbulence (ODT) simulations. It is motivated by the need to understand how these fluxes scale with parameters related to the fluid molecular properties and background shear. Comparisons are made throughout with previous models and available measurements. In unsheared interfaces, ODT simulations show that the dimensionless heat fluxNuscales with the stability parameterRρ, Rayleigh numberRaand Prandtl numberPrasNu~ (Ra/Rρ)0.37±0.03whenPrvaries from 3 to 100 and asNu~ (Ra/Rρ)0.31Pr0.22±0.04whenPrvaries from 0.01 to 1. HereRa/Rρcan be seen as the ratio of destabilizing and stabilizing effects. The simulation results also indicate that the ratio of salt and heat fluxesRfis independent ofPr, scales with the Lewis numberLeasRf~Le0.41±0.04whenRρis large enough and deviates from this expression for low values ofRρ, when the interface becomes heavily eroded. In sheared interfaces, the simulations show three flow regimes. When the Richardson numberRi≪ 1, shear-induced mixing dominates, the heat flux scales with the horizontal velocity difference across the interface andRf=Rρ. NearRi~ 1 the heat and salt fluxes are seen to increase abruptly as the shear increases. The flow structure and scaling of the fluxes are similar to those of unsheared interfaces whenRi≫ 1.

Qi, Jin, Yue Wang e Jiequan Li. "Remapping-Free Adaptive GRP Method for Multi-Fluid Flows I: One Dimensional Euler Equations". Communications in Computational Physics 15, n. 4 (aprile 2014): 1029–44. http://dx.doi.org/10.4208/cicp.140313.111013s.

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AbstractIn this paper, a remapping-free adaptive GRP method for one dimensional (1-D) compressible flows is developed. Based on the framework of finite volume method, the 1-D Euler equations are discretized on moving volumes and the resulting numerical fluxes are computed directly by the GRP method. Thus the remapping process in the earlier adaptive GRP algorithm [17,18] is omitted. By adopting a flexible moving mesh strategy, this method could be applied for multi-fluid problems. The interface of two fluids will be kept at the node of computational grids and the GRP solver is extended at the material interfaces of multi-fluid flows accordingly. Some typical numerical tests show competitive performances of the new method, especially for contact discontinuities of one fluid cases and the material interface tracking of multi-fluid cases.

Lorke, Andreas, e Frank Peeters. "Toward a Unified Scaling Relation for Interfacial Fluxes". Journal of Physical Oceanography 36, n. 5 (1 maggio 2006): 955–61. http://dx.doi.org/10.1175/jpo2903.1.

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Abstract Interfacial fluxes, that is, gas exchange at the water–atmosphere interface and benthic fluxes at the sediment–water interface, are often parameterized in terms of wind speed or turbulent friction velocity, with numerous empirical relationships obtained from individual experiments. The present study attempts to combine the general outcome of such experiments at both interfaces into a universal scaling relation for the thicknesses of the viscous and diffusive sublayers in terms of the Kolmogorov and Batchelor length scales, respectively. Transfer velocities can then be described in terms of the Schmidt number of the respective tracer and in terms of the turbulence dissipation rate. Applying law-of-the-wall scaling to convert dissipation rates into an appropriate friction velocity estimate results in a mechanistic description of the transfer velocity, which is comparable to common empirical parameterizations. It is hypothesized, however, that the dissipation rate and hence the directly estimated level of turbulence provide a more appropriate variable for the parameterization of interfacial fluxes than wind speed or turbulent friction velocity inferred from law-of-the-wall scaling.

Ilyin, Dan V., e Snezhana I. Abarzhi. "Interface dynamics with heat and mass fluxes". Physics Letters A 426 (febbraio 2022): 127827. http://dx.doi.org/10.1016/j.physleta.2021.127827.

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Schmalzried, Hermann. "Chemical kinetics at solid-solid interfaces". Pure and Applied Chemistry 72, n. 11 (1 gennaio 2000): 2137–47. http://dx.doi.org/10.1351/pac200072112137.

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The kinetics of solid-solid interfaces controls in part the course of heterogeneous reactions in the solid state, in particular in miniaturized systems. In this paper, the essential situations of interface kinetics in solids are defined, and the basic formal considerations are summarized. In addition to the role interfaces play as resistances for transport across them, they offer high diffusivity paths laterally and thus represent two-dimensional reaction media. Experimental examples will illustrate the kinetic phenomena at static and moving boundaries, including problems such as exchange fluxes, boundary-controlled solid-state reactions, interface morphology, nonlinear phenomena connected with interfaces, and reactions in and at boundaries, among others.

Carpenter, J. R., e M. L. Timmermans. "Does Rotation Influence Double-Diffusive Fluxes in Polar Oceans?" Journal of Physical Oceanography 44, n. 1 (1 gennaio 2014): 289–96. http://dx.doi.org/10.1175/jpo-d-13-098.1.

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Abstract The diffusive (or semiconvection) regime of double-diffusive convection (DDC) is widespread in the polar oceans, generating “staircases” consisting of high-gradient interfaces of temperature and salinity separated by convectively mixed layers. Using two-dimensional direct numerical simulations, support is provided for a previous theory that rotation can influence DDC heat fluxes when the thickness of the thermal interface sufficiently exceeds that of the Ekman layer. This study finds, therefore, that the earth’s rotation places constraints on small-scale vertical heat fluxes through double-diffusive layers. This leads to departures from laboratory-based parameterizations that can significantly change estimates of Arctic Ocean heat fluxes in certain regions, although most of the upper Arctic Ocean thermocline is not expected to be dominated by rotation.

Più fonti

Tesi sul tema "Interface fluxes":

Krueger, Kathryn Marie. "Metal fluxes across the sediment water interface in a drinking water reservoir". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90297.

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Elevated concentrations of iron (Fe) and manganese (Mn) in drinking water degrade water quality by affecting taste, odor, and color. Under oxic conditions (dissolved oxygen (DO) >2 mg/L), Fe and Mn are rarely present in soluble form in natural waters, as they occur as insoluble, oxidized minerals in sediments. However, the development of low DO concentrations in the bottom waters of some lakes and drinking water reservoirs during thermal stratification can lead to the reduction of oxidized, insoluble Fe and Mn in sediments to soluble forms, which are then released into the water column. In response, many water utilities have installed oxygenation systems to control metal concentrations in situ in drinking water reservoirs. However, previous research has found anoxic (DO < 0.5 mg/L) conditions still develop within sediments, even with operational oxygenation systems, allowing for the reduction and release of soluble Fe and Mn into the water column. To examine the drivers of metal release from sediments into the water column, I conducted sediment flux chamber experiments to directly quantify Fe and Mn fluxes at the sediment-water interface of a small, eutrophic drinking water reservoir (Falling Creek Reservoir, Vinton, VA). The experiments were conducted twice during the 2018 summer stratification period (April 24 – October 21). Using the flux chambers, I measured total and soluble Fe and Mn concentrations under changing oxygen conditions over 10-day periods to calculate fluxes. Throughout the experiments, I monitored DO, oxidation-reduction potential (ORP), temperature, and pH. In addition to the direct measurements, I also estimated metal fluxes using a mass balance method, which relies on measurements of metal inputs and outputs into the bottom waters of the reservoir. Overall, our results showed that fluxes are highly variable during the stratification period, with some periods having positive fluxes (release of metals from sediment to the water column) and some with negative fluxes (return of metals from the water column to sediment). The metal fluxes are highly sensitive to redox conditions in the water column, sediment-water interface and sediments. Metal fluxes measured using the chambers are 91-105% higher than those estimated using the mass balance method. This difference supports result of previous work that the flux chamber method likely provides maximum values of metal fluxes as the isolated chamber water does not allow for mixing with the bottom waters. In contrast, because the mass balance method relies on water column data, results are affected by mixing and biogeochemical reactions that can remove metals from the water column; thus, flux estimates using this method likely reflect minimum values. However, when used together, these two methods provide a useful tool for constraining metal fluxes under different redox conditions and highlight the importance of measuring ORP in addition to DO. The results of this study can be used by water utilities to improve the effectiveness of engineered oxygenation systems and water quality management practices related to iron and manganese.
Master of Science
In many drinking water reservoirs, elevated concentrations of metals, such as iron (Fe) and manganese (Mn), pose a challenging water quality problem. Elevated metal concentrations affect taste, color, and odor in drinking water and can be expensive to treat for. The presence of Fe and Mn in water is influenced by the oxygen concentrations in the water. When oxygen levels in the water are high, Fe and Mn are not soluble in water. However, when the oxygen levels in water are low, Fe and Mn can be released from soils, sediments and rocks into water and can thus pose a concern for drinking water quality. Many water utilities have installed systems to increase oxygen concentrations in drinking water reservoirs with the goal of maintaining low levels of metals in water supplies. However, previous research has shown that even when oxygenation systems are operational, Fe and Mn can still be released into water from the reservoir’s bottom sediments. To examine the factors that contribute to the release of metals from the sediments into the water column, I measured the rate of release of Fe and Mn from the sediments into the water column at a local drinking water reservoir (Falling Creek Reservoir, Vinton, VA). I conducted the experiments twice during summer 2018 using chambers that isolated the water immediately above the sediments. During the experiments, I monitored how Fe and Mn concentrations changed over time under different oxygen conditions. In addition to the measurements, I also used a mass balance method using water column data to estimate the metal release. Overall, results showed that release rates are highly variable during the summer months, with some periods having positive rates (releasing metals from sediments into the water column) and some with negative rates (returning metals from the water column to sediment). The metal release rate are highly sensitive to oxygen conditions in the water column, at the sediment-water interface and in the sediments. When used together, these two methods provide a useful tool for constraining metal release rates under different oxygen conditions. This research will help drinking water plant managers to improve the effectiveness of oxygenation systems and water quality management practices related to Fe and Mn. Additionally, this research will help improve the water quality for residents and can be applied to other lakes and reservoirs where metal concentrations are elevated.

Couto, Vanessa Barcelos. "Fluxos de amônia e óxido nitroso na interface ar-água do sistema lagunar de Maricá-Guarapina". Niterói, 2017. https://app.uff.br/riuff/handle/1/3604.

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Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-05-16T17:00:09Z No. of bitstreams: 1 Microsoft Word - Vanessa Dissertaçao.pdf: 1678884 bytes, checksum: ee88f8d0505bb8844a68dc56e1473779 (MD5)
Made available in DSpace on 2017-05-16T17:00:09Z (GMT). No. of bitstreams: 1 Microsoft Word - Vanessa Dissertaçao.pdf: 1678884 bytes, checksum: ee88f8d0505bb8844a68dc56e1473779 (MD5)
Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ
Este estudo analisa os fluxos de óxido nitroso (N 2 O) e amônia (NH 3 ) no Sistema Lagunar de Maricá-Guarapina (SLMG). O N 2 O é um dos gases do efeito estufa e está envolvido no consumo de ozônio (O 3 ) na estratosfera. A NH 3 pode levar a acidificação de ambientes terrestres e aquáticos, a eutrofização de sistemas aquáticos e produção de N 2 O. O SLMG vem sofrendo degradação da qualidade de suas á guas devido à urbanização e às atividades agropecuárias na região. Este sistema la gunar é composto por quatro lagoas interligadas entre si através de canais: Maricá, Ba rra, Padre e Guarapina. Para a análise de N 2 O foi utilizada a técnica da câmara estática flutua nte e 4 modelos de predição de fluxos (MPF). No caso da NH 3 foram feitas estimativas de fluxos também através de MPF. Os resultados deste estudo mostram que as quatro lagoa s do SLMG apresentam comportamentos distintos com relação aos fluxos dos dois gases ana lisados. As estimativas de taxas de emissão do sistema lagunar mostram que, apesar do sistema a presentar lagoas que parecem atuar como sorvedouro de N 2 O ou de NH 3 , num balanço geral, ele emite N para a atmosfera s ob uma ou outra forma. A taxa de emissão estimada variou entr e 92,15 g N dia -1 e 104,77 g N dia -1 . Outra informação que esta estimativa trouxe foi a d e que a maior parte das emissões ocorre sob a forma de NH 3 com emissão estimada de 84,79 g N dia -1 a 97,41 g N dia -1 .
This study examines the nitrous oxide (N 2 O) and ammonia (NH 3 ) fluxes in Maricá- Guarapina’s system. The N 2 O is a greenhouse gas and is involved in the consum ption of the ozone (O 3 ) in the stratosphere. The NH 3 can lead to acidification of terrestrial and aquat ic environments, eutrophication of aquatic systems and production of N 2 O. The SLMG is suffering degradation in the water’s quality due to urbanization and agricultural activities in the region. This system is composed for four lagoon interconnected between themselves through channels: Maricá, Barra, Father and Guarapi na. For the analysis of N 2 O was used the technique of the static chamber and 4 models predic tion fluxes (MPF). In the case of NH 3 were made estimates of fluxes through MPF too. The results of this study show that the four lagoons in the SLMG have different behaviors with r espect to the fluxes of the two gases analyzed. Estimates of the rates of emission in th e system lagoon show that despite the present system lagoons that seem act as sink of N 2 O and NH 3 , in a general balance, it gives N to the atmosphere in one form or another. The estim ated emission rate ranged between 92,15 g N -1 day -1 and 104,77 g N -1 day -1 . Other information that brought this estimate was that the majority of emissions occur in the form of NH 3 with estimated emission of 84,79 g N -1 day -1 to 97,41 g N -1 day -1 .

Couceiro, F. "A comparison of nutrient fluxes across the sediment-water interface at two intertidal sites in Strangford Lough". Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431539.

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Knobloch, Amanda. "Fluxes, drivers, and composition of carbon exchanged at the Taskinas Creek, VA coastal marsh creek-estuarine interface". W&M ScholarWorks, 2019. https://scholarworks.wm.edu/etd/1582642587.

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Among the most valuable natural ecosystems, estuaries and marshes are areas of high productivity, have high economic value, and provide numerous ecosystem services. However, there is still uncertainty in marsh and estuarine carbon budgets and in our overall understanding of the drivers, composition, and fluxes of organic matter in these habitats. Part of this uncertainty is due to high spatial and temporal variability within these habitats and the range of methods used in previous studies. While the number of studies is increasing, there are still large gaps in our knowledge of marsh-estuarine interface dynamics. This study examined the concentrations, fluxes, and composition of particulate and dissolved organic carbon (POC, DOC) and dissolved inorganic carbon (DIC), with a focus on the temporal patterns and drivers of carbon pools at the marsh-estuarine interface. Taskinas Creek, a Chesapeake Bay National Estuarine Research Reserve, was chosen for this study as it provides a near-pristine location to measure current baseline data and is equipped with long-term water quality and meteorological monitoring stations that provided valuable ancillary data. Water samples were collected from Taskinas Creek from 2013 to 2018 to measure POC, DOC, and DIC concentrations, stable isotopes of carbon and nitrogen, colored dissolved organic matter (CDOM), and lipid biomarker compounds. Linear mixed effects (LME) modeling identified that the total suspended sediments were the primary driver of POC concentrations and marsh sources were the primary drivers of both DOC and DIC. Measured carbon concentrations were then used calculate carbon fluxes based on parameters measured via continuous water quality monitoring at Taskinas Creek, allowing for a high-frequency, long-term carbon flux record. On an annual basis, the marsh acted as a source of carbon to the York River (53 g C m-2 y-1) but the fluxes of the different pools of carbon differed in direction and magnitude. On a net basis, the York River was a source organic matter to the marsh (58 to 77 g POC m-2 yr-1 and 3.9 to 18 g DOC m-2 yr-1) whereas DIC was exported from the marsh (114 to 193 g DIC m-2 yr-1). Stable isotopes, lipid biomarkers, and CDOM were used to determine the primary sources of organic matter at Taskinas Creek. Lipid biomarker and stable isotope analyses revealed that POC was primarily derived from algal sources, likely originating from the adjacent York River. In contrast, CDOM spectral measurements and stable isotopes of DOC and DIC indicated that dissolved carbon was primarily marsh-derived, and CDOM was primarily composed of humic-like and fulvic-like compounds. These results agree with previous studies conducted in similar habitats and within the York River estuary. The import of labile POC into the marsh and the export of DOC, DIC, and CDOM to the estuary can have important consequences for marsh and estuarine food webs, marsh surface stability, and the overall biogeochemistry of these habitats. The results found in this study can be used to improve carbon budget models by not only providing current baseline carbon concentrations, but also the primary drivers and sources of these carbon pools. As these drivers and sources may face changes in times of future anthropogenic and climate change, understanding how they affect carbon pools can enable better predictions of how these carbon pools will change in the future.

Bryant, Lee Davis. "Dynamic forcing of oxygen, iron, and manganese fluxes at the sediment-water interface in lakes and reservoirs". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77337.

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The National Research Council recently called for a more interdisciplinary approach to drinking water research to address the critical issue of global drinking water supplies. Hypolimnetic oxygenation systems (HOₓ) are being increasingly used to improve water quality in stratified reservoirs by increasing dissolved oxygen (O₂) concentrations and subsequently suppressing the release of soluble species such as iron (Fe) and manganese (Mn) from the sediment into the water. However, while the influence of HOx on the water column has been established, little work has been done on how oxygenation affects sediment O₂ uptake (i.e., sediment oxygen demand) and other sediment-water fluxes. In response to the growing need for alternative approaches for improving water quality, we conducted highly interdisciplinary research to evaluate how O₂, Fe, and Mn cycling at the sediment-water interface is influenced by both natural and HOx-induced variations in water column dynamics, chemical redox processes, and microbial activity within the sediment, all of which may govern sediment-water fluxes. Studies were performed in an alpine lake in Switzerland and in an HOₓ-equipped drinking-water-supply reservoir in Virginia. This research was based on in situ field campaigns paired with laboratory experiments, microbial analyses, and computer simulation to elucidate variable sediment O₂ uptake and corresponding Fe and Mn cycling. This work is unique in that sediment-water fluxes were assessed using in situ data from both sides of the sediment-water interface. Results show that sediment O₂ uptake flux is strongly controlled by both wind- and HOₓ-induced dynamic forcing. Our findings reveal that Fe and Mn fluxes were suppressed from the bulk hypolimnion via biogeochemical cycling in the oxic benthic region. Results also indicate that the sediment microbial community structure may directly respond to HOₓ-induced variation in sediment O₂ availability. Additionally, based on an analysis of the robustness of several commonly used methods for flux calculations, we show that flux estimates are not strongly dependent on the method chosen for analysis. Ultimately, by emphasizing the highly transient nature of sediment O₂ uptake, this research will aid in accurate characterization of various sediment-water fluxes and corresponding water quality. Our results will also directly contribute to the optimization of HOₓ operations and lake and reservoir management.
Ph. D.

Murniati, Erni [Verfasser], e Andreas [Akademischer Betreuer] Lorke. "Physical-biological interactions controlling the variability of oxygen fluxes across the sediment-water interface / Erni Murniati ; Betreuer: Andreas Lorke". Landau : Universität Koblenz-Landau, Campus Landau, 2018. http://d-nb.info/1154434567/34.

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Read, Deborah J. "The role of labile dissolved organic carbon in influencing fluxes across the sediment-water interface : from marine systems to mine lakes". University of Western Australia. School of Environmental Systems Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0144.

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Sediment diagenesis in aquatic systems is usually understood to be controlled by the concentrations of both organic carbon and the oxidant. However, the concept that sediment respiration may be limited by the supply of organic carbon, even in systems with moderate concentrations of organic carbon in the water column, has yet to be fully explored. Typically we assume that a direct coupling between water column and sediment diagenesis processes occurs and the chemical evolution of porewater and surface water are linked through fluxes of chemical species across the sediment-water interface. While the dynamics of supply of particulate organic carbon (POC) to the sediments via plankton deposition and resuspension, has previously been examined, the fate of dissolved organic carbon (DOC) once in the sediments, has rarely been investigated. A series of experiments comprising batch tests, microcosms and sediment cores were conducted on sediment and water from four diverse field sites in which sediment respiration was considered to be carbon limited. Three sites were oligotrophic, acidic lakes and the fourth an oligotrophic coastal embayment. During each experiment dissolved organic carbon was added and measurements were undertaken of solutes that were considered participants in diagenetic processes. While each system differed in its chemical, biological and geological makeup, a key commonality was the rapid onset of anoxic conditions in the sediments irrespective of the overlying water oxygen concentrations, indicating lack of direct coupling between biogeochemical processes in the water column and sediments. Also, similar apparent DOC remineralisation rates were observed, measured solute fluxes after the addition of DOC indicated adherence to the ecological redox sequence, and increased ammonium concentrations were measured in the overlying waters of the acidic microcosms. In marine system experiments it was noted that diagenetic respiration, as indicated by decreasing concentrations of oxygen in the overlying water, increased rapidly after labile DOC was added. To explore the influence of geochemical processes on sediment respiration, a diagenetic model was tested against the laboratory data. The model was able to capture the rapid changes observed in the microcosms after addition of DOC in both the marine and acidic systems experiments. The model has the potential to serve as an essential tool for quantifying sediment organic matter decomposition and dissolved chemical fluxes. This work has focussed our attention on the control of DOC availability on sediment respiration and thus its ultimate control on solute fluxes across the sediment water interface. The results highlight the need to understand and quantify the supply of DOC to the sediment (as POC or already as the dissolved form), its transport through the sediment and its eventual remineralisation. This understanding is critical for improved management of aquatic systems, possibly even in systems where water column organic carbon is plentiful but sediment respiration is constrained by high organic carbon turnover rates in the water column and a resulting low flux of organic carbon to the sediment.

Cambra, Rémi. "Etude des flux turbulents à l'interface air-mer à partir de données de la plateforme OCARINA". Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLV024/document.

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Les échanges de chaleur et de quantité de mouvement à l'interface-océan atmosphère jouent un rôle majeur dans la formation et la dynamique des masses d'air et d'eau. Malgré des décennies de recherche, nous avons encore besoin d'améliorer nos connaissances sur ces échanges, et plus spécifiquement nos connaissances sur les flux turbulents, qui sont des variables clés dans les modèles météorologiques et de climat. Dans ces modèles, les processus turbulents sont des processus sous-maille, non-résolus explicitement, ainsi les flux turbulents doivent être modélisés, au travers de paramétrisations, qui sont pour la plupart réalisées à partir de la théorie des similitudes de Monin-Obukhov [1954]. Cependant, d'une part, l'utilisation d'un modèle implique que les coefficients doivent être ajustés. D'autre part, le modèle lui-même peut demander des améliorations. Malheureusement, l'obtention d'estimations de flux avec une bonne précision est un gros défi, à cause des effets intrusifs de la plate-forme sur la mesure, de la précision limité des instruments et des capacités d'échantillonnages propres de chaque instrument.Notre étude porte sur l'estimation des flux turbulents en mer à partir de mesures réalisées avec la nouvelle plate-forme OCARINA (trimaran autonome) lors des campagnes STRASSE 2012 et AMOP 2014. Nous analysons les caractéristiques de la turbulence dans la couche limite de surface, nous estimons les flux turbulents par différentes méthodes, et nous comparons les valeurs des flux en fonction des conditions environnementales, en prenant en compte l'état de mer
Exchanges of heat and momentum at the air-sea interface play a major role in the formation and the dynamics of water and air masses. In spite of decades of research, we still need to improve our knowledge of these exchanges, and more specifically our knowledge of turbulent fluxes, which are key variables in meteorological and climate models. In these models, sub-grid turbulent processes, thus turbulent fluxes also have to be modeled, which is mostly done with the Monin-Obukhov (1954, MOS hereafter) similarity theory. However, on the one hand, the use of a model implies that coefficients have to be adjusted. On the other hand, the model itself may require improvements. Unfortunately, obtaining flux estimates that have a good accuracy is a challenging effort, because of the intrusive effect of the platform, the limited accuracy the instruments, and because the instruments have their own sampling volume.Our study focuses on the estimation of turbulent fluxes at sea from measurements made with the new OCARINA platform (autonomous trimaran) during two campaigns : STRASSE 2012 and AMOP 2014. We analyze the characteristics of turbulence in the surface boundary layer, we estimate the turbulent fluxes by different methods, and compare the values of fluxes depending on environmental conditions, taking into account the sea state

Burton, Evans Jessica Landis. "The effect of benthic microalgal photosynthetic oxygen production on nitrogen fluxes across the sediment-water interface in a shallow, sub-tropical estuary". College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2998.

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Thesis (M.S.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

BONSIGNORE, Maria. "The biogeochemical cycle of mercury in the Augusta Bay". Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/91305.

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Mercurial, the metaphor for volatile unpredictable behavior, aptly reflects the complexities of one of the most insidiously interesting and scientifically challenging biogeochemical cycles at the Earth’s surface. At the base of this toxic metal cycle there is the conversion between the different Hg chemical species, in which the balance between the reduced and oxidized forms depends primary on redox system conditions. The potential risks of human exposure to Hg, especially in the form of monomethylmercury (MMHg), particularly prenatally, and the potential deleterious ecological consequences from localized to global scale Hg pollution, have given much impetus to mercury studies and regulatory activities at international level. Much of this advancement has come since the early 1970s, and the growth in mercury research continues at breakneck pace. The menace of this item for environment and human health deserves further information concerning the geochemistry of mercury, especially in coastal marine system. The Augusta Bay is a semi-enclosed marine area, located in the SE of Sicily (southern Italy), well-known because of the high Hg pollution. The area indeed has experienced, since the early 60s, a significant industrialization phase that put in several chemical and petrochemical plants and oil refineries resulting in a severe pollution of the surrounding environment. In particular, the petrochemical district of Augusta Bay hosted one of the most important chlor-alkali plant in Italy, that produced chlorine and caustic soda by electrolysis of sodium chloride aqueous solution in electrolytic cells with a graphite anode and metallic mercury cathode. Uncontrolled chemical discharge of Hg occurred in the Augusta Bay until 1978, when restrictions were imposed by the Italian legislation. For this reason, in the last decade, several studies have provided detailed information on the pollution levels and risks for human health of resident populations of Augusta Bay. The effects of this indiscriminate Hg discharge include the alarming high concentrations of the element recently measured in sediments of the basin, prompting the Italian government to include the Augusta basin in the National Remediation Plan. The “Augusta case“ menaces to not remain confined to a “local problem”, but to became a large-scale threat. Indeed, the effects of meso-scale circulation of the Ionian Sea create a higher potential risk for HgT contamination of the basin, being affected by the transit and transformation of the major water masses, which regulate the general thermohaline circulation in the upper, intermediate and deep layers, respectively. Owing to the geographical location of the Augusta basin, its outflowing shelf waters are immediately intercepted by the surface Atlantic Ionian Stream (AIS) and mixed with the main gyres of the eastern Mediterranean Sea, thus representing a risk for the large-scale marine system. This complex water circulation system, together with the closeness with the steep continental slope (part of the Malta escarpment), make the area a potential point sources of mercury for the entire Mediterranean sea, as previously speculated by Sprovieri et al. (2011). All this features make the Augusta Bay an ideal natural laboratory for deeper insights on the biogeochemical cycle of mercury in a coastal marine environment and the need to investigate the large-scale effect of Augusta Bay pollution has become imperative! With the aim to fill this requirement, an integrated model on the biogeochemical cycle of Hg has been created. Hg cycle is a very articulated topic. Once introduced in the aquatic system environment the fate of Hg in the marine system is affected by sorption/ desorption processes onto suspended particulate matter and, based on associated kinetics, it may be partially transferred from surface waters to bottom sediments. Microorganisms, at the water/sediments interface such as sulfate reducing bacteria (SRB), mediate the transformation of inorganic Hg to MMHg with high rates of methylation favored by the presence of high content of organic matter under reducing environmental conditions. Therefore, sediments are considered key contributors of MMHg to the marine ecosystem. Clearly, this analysis stresses the necessity for better knowledge of the specificity of the mercury biogeochemical cycle in this particular environment through the gathering of more data on the distribution and fluxes among the various compartments including the water column, sediment, atmosphere and biota. This multidisciplinary approach offers a nice opportunity to explore the biogeochemical dynamic of mercury in highly complex coastal areas under important anthropic impact and the potential on larger scale diffusion. Multiple oceanographic cruises, realized during 2011-2012 period, permitted to collect samples of sediments, seawaters and fishes inside and outside the Augusta Bay. Furthermore in order to trace the entire chain, from sources (polluted sediments) to sink (man), analysis of Hg in fishes (the main route of Hg uptake for humans), and toxicological aspects have been addressed. Analysis of THg in muscles and liver of some pelagic, demersal and benthic species captured inside and outside the semi-enclosed area, has been analysed in order to explore the effects of HgT pollution on fish compartment and to assess the potential health risks associated with the consumption of contaminated fish. THg content of fishes shows a wide range of concentration (range: 0.02 - 2.71 μg g-1and 0.03 -9.72 μg g-1 in muscles and in livers respectively), with highest values measured in benthic species and the lowest in pelagic ones. This increasing trend along the habitat depth suggests an active release mechanism of mercury from polluted sediments to the water column, with consequent effects of bioaccumulation in the trophic web. Anomalous THg content measured in pelagic species captured in the external zone of the bay confirms the role of the Augusta marine environment as pollutant source of Hg for the surrounding area and underscores the crucial risk associated with contaminant transfer from the basin to the open sea. Finally, values of hazard target quotient (THQ) and estimated weekly intake (EWI) demonstrate that consumption of fishes caught inside the bay represents a serious risk for human health and suggests caution in consuming demersal and benthic fishes from outside the Augusta Bay, definitively demanding for appropriate social actions. Hg distribution in sediments (range: 1.77 - 55.34 mgKg-1; mean: 13.78 ±10.72 mgKg-1) clearly divides the area into three parts, with the lowest values recorded in the northern Augusta Bay, intermediate value in the center and the highest HgT concentrations recorded in the southern part of the Augusta basin (from the Pontile Cementeria down to the dam) with decreasing values from the coastline. Despite sequential extraction procedure (SEP) documented that the most part of HgT in sediments consists of strong complexes (~80% of HgT as strong complex, ~15% of Hg as less strong forms and ~ 2% of HgT as more soluble and bioavailable forms), some anaerobic microorganisms can manage these stable Hg trapped in minerals structures as substrate for their metabolism, making Hg more easily bioavailable for the environment. Analysis of THg and DHg content at different quote of the water column, provided significant information on Hg distribution along space and depth. The HgT distribution in seawaters (range: 0.45 - 129.27 ngL-1 and >0.01 - 21.3 ngL-1 for THg and HgD respectively), putted in light an evident increasing trend of Hg content toward the southern and more contaminated part of the Augusta Bay, where waste spillage from chlor-alkali plant occurred. A clear trend was also observed on the vertical, with Hg concentration increasing near the bottom and reducing in surface water, strengthening the role of Augusta sediments as sources for the overlying water. Moreover the unexpected THg concentrations measured in seawater outside the bay (range: 2.62-11.95 ng L-1; mean: 6.46±2.95 ngL-1), confirmed the hypothesis of transport of Hg from Augusta harbor to the open sea representing a vehicle of contamination for the entire Mediterranean basin through the complex circulating currents affecting the western Ionian. In this scenario, fluxes assessment at the interface sediments-seawater-air became crucial in order to create a mass balance of Hg in the study area and to determine the net outflow for the Mediterranean sea. Detailed information on the mobilization processes from sediment to seawater and consequent escape to the atmosphere has been investigated. For this reason, for the first time in this area, a benthic chamber and a dynamic accumulation chamber, have been employed in order to evaluate fluxes at the interfaces sediments/seawater and seawater/air and to recognize equilibrium of exchanges among phases. Using in situ accumulation chamber Bagnato et al., 2013 reported an estimated sea–air Hg evasion for the entire Augusta basin (~23.5 km2) of about 9.7 ± 0.1 g d-1 (~0.004 t yr-1), accounting for ~0.0002% of the global Hg oceanic evasion (2000 t yr-1). Simultaneously using in situ benthic chamber, a total flow from sediment to seawater for the whole Augusta Bay has been estimated in 0.22 kmol y-1 in 2011 (0.05 ty-1) and 0.38 kmol y-1 in 2012 (0.11 ty-1). The mass balance calculation permitted to estimate a HgT output from the Augusta basin to Ionian surface waters (O) corresponding to an average of 1.29 kmol y-1. Analysis of Hg isotopes in sediments and fishes of the Augusta Bay, provided unique information on Hg sources in the environment and processes influencing Hg cycling. The success of such an approach strongly depends on two factors. First, different natural and anthropogenic Hg sources must have analytically discernible Hg isotope signatures. Second, the processes that transport and transform emitted or discharged Hg into the environment must not obscure the original Hg source isotope signatures. This requires that fractionation of Hg isotopes after release is either small relative to source differences or is predictable enough to be corrected for, allowing estimation of the source isotopic composition. The magnitude of mass-dependent (MDF) and mass-independent fractionation (MIF) has been described primarily as δ 202Hg and Δ201Hg. The positive MIF fractionation in fishes, especially in pelagic one, demonstrated photochemical reaction of Hg(II) prior of the intake in the marine food web. Sediments isotopes fractionation demonstrated reaction of methylmercury production biological mediated. A geographic pattern in δ202Hg and Δ199Hg values suggests that the sources of Hg to the sediment are locally controlled. Hairs exhibit positive MIF fractionation, suggesting reaction of photochemical reduction of MeHg in presence of organic matter. The overlapping δ 202Hg values of both sediments and fishes suggested sediments represent the source of Hg for fish. The positive relationship obtained by plotting Δ201Hg vs. Δ199Hg of both hairs and sediments demonstrate fish consumption represents the first pathway of exposure for human. Difference of 2‰ between δ 202Hg in fishes and values, could be due to could suggest that substantial MDF takes place during MMHg human metabolism Rare Earth Elements (REEs) are important because their geochemical properties enable them to be powerful tracers of chemical processes. Their distribution has been investigated in seawater of the Augusta Bay in order to verify if anthropogenic sign can also transpire through the investigation of REE. The REEs distribution along the water column suggests that the high dissolved organic matter created ideal condition for an increasing of REE in dissolved phases, much to hide the negative Ce anomaly usually recorded in the oligothropic water. Gd anomaly, expressed as Gd/Gd*>1, suggests significant contributions of the petrochemical industries, using gadolinium, in the form of gadolinium oxide, as petroleum cracking catalyst. A common thread, started from the evaluation of Hg in the key component of the cycle, the study of fluxes at the interfaces, the evaluation of Hg isotopic fractioning and the REE distribution in water column, permitted to evaluate the fate of Hg in the Augusta Bay and the main processes rule the Hg biogeochemical cycle.

Più fonti

Libri sul tema "Interface fluxes":

L, Golterman H., Bonin Daniel J e Joint Congress of Limnology and Oceanography (1989 : Marseille, France), a cura di. Fluxes between trophic levels and through the water-sediment interface. Dordrecht: Kluwer Academic Publishers, 1990.

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S, Balistrieri Laurie, e Geological Survey (U.S.), a cura di. Metal fluxes across the sediment-water interface in Terrace Reservoir, Colorado. [Denver, CO]: U.S. Geological Survey, 1996.

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S, Balistrieri Laurie, e Geological Survey (U.S.), a cura di. Metal fluxes across the sediment-water interface in Terrace Reservoir, Colorado. [Reston, Va.]: U.S. Dept. of the Interior, U.S. Geological Survey, 1996.

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Banin, Amos. N₂O fluxes at the soil-atmosphere interface in various ecosystems, and the global N₂O budget: Final report. Los Altos, CA: Seti Institute, 1987.

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United States. National Aeronautics and Space Administration., a cura di. N₂O fluxes at the soil-atmosphere interface in various ecosystems, and the global N₂O budget: Final report. Los Altos, CA: Seti Institute, 1987.

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Science, National Research Council (U S. ). Committee on Hydrologic. Groundwater fluxes across interfaces. Washington, D.C: National Academies Press, 2004.

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Freyland, Werner. Coulombic fluids: Bulk and interfaces. Berlin: Springer, 2011.

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Sciré, Claudia. Consumo popular, fluxos globais: Práticas e artefatos na interface entre a riqueza e a pobreza. [São Paulo, Brazil]: FAPESP, 2012.

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Carlo, Gualtieri, e Mihailovic Dragutin T, a cura di. Fluid mechanics of environmental interfaces. London: Taylor & Francis, 2008.

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Onuki, Akira. Dynamics and Patterns in Complex Fluids: New Aspects of the Physics-Chemistry Interface. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990.

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Più fonti

Capitoli di libri sul tema "Interface fluxes":

Downing, John P., Michel Meybeck, James C. Orr, R. R. Twilley e H.-W. Scharpenseel. "Land and Water Interface Zones". In Terrestrial Biospheric Carbon Fluxes:, 123–37. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1982-5_8.

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Robinson, Ian S., e Susanne Fangohr. "Fluxes through the air–sea interface". In Discovering the Ocean from Space, 359–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-68322-3_10.

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Brown, Gary S. "Quasi-Specular Scattering from the Air-Sea Interface". In Surface Waves and Fluxes, 1–39. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0627-3_1.

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Plant, William J. "Bragg Scattering of Electromagnetic Waves from the Air/Sea Interface". In Surface Waves and Fluxes, 41–108. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0627-3_2.

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Dunham, Scott T. "Interstitial Fluxes During Silicon Oxidation". In The Physics and Chemistry of SiO2 and the Si-SiO2 Interface, 477–84. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4899-0774-5_53.

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Nedwell, D. B., R. J. Parkes, A. C. Upton e D. J. Assinder. "Seasonal fluxes across the sediment—water interface, and processes within sediments". In Understanding the North Sea System, 141–51. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1236-9_11.

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Hélie, Jean-François, e Claude Hillaire-Marcel. "Diffusive CO2 Flux at the Air-Water Interface of the Robert-Bourassa Hydroelectric Reservoir in Northern Québec : Isotopic Approach (13C)". In Greenhouse Gas Emissions — Fluxes and Processes, 339–54. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/978-3-540-26643-3_15.

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Adams, Donald D. "Diffuse Flux of Greenhouse Gases — Methane and Carbon Dioxide — at the Sediment-Water Interface of Some Lakes and Reservoirs of the World". In Greenhouse Gas Emissions — Fluxes and Processes, 129–53. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/978-3-540-26643-3_6.

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van Eck, G. Th M., e J. G. C. Smits. "Calculation of Nutrient Fluxes Across the Sediment-Water Interface in Shallow Lakes". In Sediments and Water Interactions, 289–301. New York, NY: Springer New York, 1986. http://dx.doi.org/10.1007/978-1-4612-4932-0_24.

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Muhmood, Luckman, Nurni N. Viswanathan e Seshadri Seetharaman. "Modelling and Experimental Studies of Diffusivity of Sulfur and Its Relevance in Observing Surface Oscillations at the Slag Metal Interface Through X-Ray Imaging". In Advances in Molten Slags, Fluxes, and Salts, 581–87. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119333197.ch62.

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Atti di convegni sul tema "Interface fluxes":

Li, Like, Chen Chen, Renwei Mei e James F. Klausner. "Conjugate Interface Heat and Mass Transfer Simulation With the Lattice Boltzmann Equation Method". In ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-21864.

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An interface treatment for conjugate heat and mass transfer in the lattice Boltzmann equation (LBE) method is proposed based on our previously proposed second-order accurate Dirichlet and Neumann boundary schemes. The continuity of temperature (concentration) and its flux at the interface for heat (mass) transfer is intrinsically satisfied without iterative computations, and the interfacial temperature (concentration) and their fluxes are conveniently obtained from the microscopic distribution functions without finite-difference calculations. The present treatment takes into account the local geometry of the interface so that it can be directly applied to curved interface problems such as conjugate heat and mass transfer in porous media. For straight interfaces or curved interfaces with no tangential gradient, the coupling between the interfacial fluxes along the discrete lattice velocity directions is eliminated and thus the proposed interface schemes can be greatly simplified. Several numerical tests are conducted to verify the applicability and accuracy of the proposed conjugate interface treatment, including: (i) steady convection-diffusion in a channel containing two different fluids, (ii) unsteady convection-diffusion in the channel, and (iii) steady heat conduction inside a circular domain with two different solid materials. The accuracy and order-of-convergence of the simulated interior temperature (concentration) field, the interfacial temperature (concentration) and heat (mass) flux are examined in detail and compared with those obtained from the “half lattice division” treatment in the literature. The present analysis and numerical results show that the half lattice division scheme is second-order accurate only when the interface is fixed at the center of the lattice links while the present treatment preserves second-order accuracy for arbitrary link fractions. For curved interfaces, the present treatment yields second-order accurate interior and interfacial temperatures (concentrations) and first-order accurate interfacial heat (mass) flux. An increase of order-of-convergence by one degree is obtained for each of these three quantities compared with the half lattice division scheme.

Cascarano, Ryan N., Donald M. Reeves e Mark Henry. "CHARACTERIZING FLUXES AT THE GROUNDWATER-SURFACE WATER INTERFACE USING DYE TRACERS". In 52nd Annual North-Central GSA Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018nc-311848.

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Cali, Philip M., Vincent Couaillier e Antony Jameson. "Conservative Interfacing for Turbomachinery Applications". In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0357.

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This paper presents the development of a conservative interface technique designed for turbomachinery applications involving multiple rows of blades. Instead of interpolating solution information between blade rows, unique patch boundaries are defined at rotor/stator interfaces on which numerical fluxes are evaluated directly. The fluxes are then distributed to both sides of the interface in a fully conservative fashion. Accuracy is maintained by representing the primitive variables in each interface cell using a system of quadratic polynomials. The coefficients of each polynomial are calculated using neighboring flow information from both sides of the interface. In order to make the reconstruction process more tenable, the current implementation is restricted to pairs of blade rows which maintain identical axisymmetric radial distributions of points at their juncture. Preliminary inviscid flow results show significant improvements in solution quality relative to calculations conducted using conventional nonconservative interpolation techniques.

Moraga, Francisco J., Martin Vysohlid, Natalia Smelova, Hiteshkumar Mistry, Siram Atheya e Vasudevarao Kanakala. "A Flux-Conservation Mixing Plane Algorithm for Multiphase Non-Equilibrium Steam Models". In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68660.

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The accuracy of steady multistage turbomachinery calculations is dependent on the exchange of information at an interface, also known as mixing plane, between adjacent blade rows. This paper describes an extension of already available flux conservation mixing plane algorithm to the Eulerian-Eulerian non-equilibrium steam model. Since algorithms that conserve fluxes across the interface have been found to be more accurate and robust, greater emphasis is on the conservation of mixture and droplet fluxes across the interface. The key characteristics of the algorithm are provided, along with its application on simple two- and three-dimensional blade rows.

Schreiber, Madeline E., Kathryn Krueger, Claire Vavrus, Mary Lofton, Ryan McClure, Paul Gantzer e Cayelan C. Carey. "METAL FLUXES ACROSS THE SEDIMENT-WATER INTERFACE IN A DRINKING WATER RESERVOIR". In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-339440.

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Wang, Yuan, Khellil Sefiane e Rachid Bennacer. "Pressure Drop and Two Phase Flow During Boiling of FC-72 in a High Aspect Ratio Micro-Channel". In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23336.

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Liquid-vapour interface behaviours and the pressure drop fluctuation during flow boiling in a single rectangular micro-channel with high aspect ratio were experimentally investigated in the present study. A micro-channel with the hydraulic diameter of 727 μm was chosen, the aspect ratio of which was 10. FC-72 was used as the working liquid. Wide ranges of mass fluxes and heat fluxes were tested to study bubble dynamics and hydraulic instabilities during flow boiling. With the aid of high speed camera, various liquid-vapour interface behaviours during flow boiling were captured, such as bubble nucleation and growth, interface deformation, recoiling and rewetting. Based on the interface movement, the evaporation rate of the liquid was discussed. Evaporation rates of bubble nose and bubble tail at different mass fluxes and heat fluxes were compared. Besides, the effects of thermal and flow conditions on bubble geometry were discussed. Moreover, the pressure fluctuations resulting from boiling instabilities was remarkable. Fluctuation frequency was largely affected by the heat and mass fluxes.

Pearce, Alexandra R., Elizabeth A. Hasenmueller e Lisa G. Chambers. "CHARACTERIZING NUTRIENT FLUXES AT THE SEDIMENT-WATER INTERFACE IN A EUTROPHIC MIDWESTERN RESERVOIR". In 50th Annual GSA North-Central Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016nc-275567.

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Gao, Zengwen, Xi-Lai Zheng, Wei Li e Hui Song. "Determination of Nutrient Fluxes Across the Sediment-Water Interface in a Nitrate-Rich Reservoir". In 2008 2nd International Conference on Bioinformatics and Biomedical Engineering. IEEE, 2008. http://dx.doi.org/10.1109/icbbe.2008.1159.

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Cascarano, Ryan N., Donald M. Reeves e Mark Henry. "USE OF FLUORESCEIN DYE FOR CHARACTERIZING HYDROLOGIC FLUXES AT THE GROUNDWATER - SURFACE WATER INTERFACE". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-303145.

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Falabino, Matteo, Daniele Sciannandrone, Emiliano Masiello e Jean-François Vidal. "The MPN Method: A New Angular Discretization Method Based on Piecewise Polynomial Interface Fluxes". In International Conference on Physics of Reactors 2022. Illinois: American Nuclear Society, 2022. http://dx.doi.org/10.13182/physor22-37377.

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Rapporti di organizzazioni sul tema "Interface fluxes":

Goyet, C. Observation and modeling of CO{sub 2} fluxes at the ocean-atmosphere interface. Final report. Office of Scientific and Technical Information (OSTI), dicembre 1998. http://dx.doi.org/10.2172/764714.

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Zika, R. G., e P. J. Milne. Use of a laser based monitoring technique to measure trace gas fluxes across the air-sea interface. Office of Scientific and Technical Information (OSTI), gennaio 1991. http://dx.doi.org/10.2172/6206790.

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Frink, L. J. D., e A. G. Salinger. Density Functional Theory for Classical Fluids at Complex Interfaces: (TRAMONTO 1.0: Methods, Applications, and User's Guide). Office of Scientific and Technical Information (OSTI), gennaio 1999. http://dx.doi.org/10.2172/3193.

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Blumwald, Eduardo, e Avi Sadka. Sugar and Acid Homeostasis in Citrus Fruit. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7697109.bard.

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Abstract (sommario):

Citrus fruit quality standards have been determined empirically, depending on species and on the particular growing regions. In general, the TSS (total soluble solids) to total acidity (TA) ratio determines whether citrus fruit can be marketed. Soluble sugars account for most of the TSS during harvest while TA is determined almost solely by the citric acid content, which reaches levels of 1-5% by weight in many cultivated varieties. Acid and sugar homeostasis in the fruit is critical for the management of existing cultivars, the development of new cultivars, the improvement of pre- and post-harvest strategies and the control of fruit quality and disorders. The current proposal (a continuation of a previous proposal) aimed at: (1) completing the citrus fruit proteome and metabolome, and establish a citrus fruit functional database, (2) further characterization of the control of fruit acidity by studying the regulation of key steps affecting citrate metabolism, and determine the fate of citrate during acid decline stage, and (3) Studying acid and sugar homeostasis in citrus fruits by characterizing transport mechanisms across membranes. These aims were completed as the following: (1) Our initial efforts were aimed at the characterization and identification of citric acid transporters in citrus juice cells. The identification of citrate transporters at the vacuole of the citrus juice cell indicated that the steady-state citrate cytosolic concentration and the action of the cytosolic aconitase were key elements in establishing the pH homeostat in the cell that regulates the metabolic shift towards carbon usage in the fruit during the later stages of fruit development. We focused on the action of aconitase, the enzyme mediating the metabolic use of citric acid in the cells, and identified processes that control carbon fluxes in developing citrus fruits that control the fruit acid load; (2) The regulation of aconitase, catalyzing a key step in citrate metabolism, was further characterized by using two inhibitors, citramalte and oxalomalte. These compounds significantly increased citrate content and reduced the enzyme’s activity. Metabolite profiling and changes of amino-acid metabolizing enzymes in oxalomalate- treated cells suggested that the increase in citrate, caused by aconitase inhibition, induces amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in citrus fruit. (3) We have placed a considerable amount of time on the development of a citrus fruit proteome that will serve to identify all of the proteins in the juice cells and will also serve as an aid to the genomics efforts of the citrus research community (validating the annotation of the fruit genes and the different ESTs). Initially, we identified more than 2,500 specific fruit proteins and were able to assign a function to more than 2,100 proteins (Katz et al., 2007). We have now developed a novel Differential Quantitative LC-MS/MS Proteomics Methodology for the identification and quantitation of key biochemical pathways in fruits (Katz et al., 2010) and applied this methodology to identify determinants of key traits for fruit quality (Katz et al., 2011). We built “biosynthesis maps” that will aid in defining key pathways associated with the development of key fruit quality traits. In addition, we constructed iCitrus (http://wiki.bioinformatics.ucdavis.edu/index.php/ICitrus), a “functional database” that is essentially a web interface to a look-up table that allows users to use functional annotations in the web to identify poorly annotated citrus proteins. This resource will serve as a tool for growers and field extension specialists.

Bowers, Geoffrey. Computational and Experimental Investigations of the Molecular Scale Structure and Dynamics of Gologically Important Fluids and Mineral-Fluid Interfaces. Office of Scientific and Technical Information (OSTI), aprile 2017. http://dx.doi.org/10.2172/1365679.

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R. James Kirkpatrick e Andrey G. Kalinichev. Computational and Spectroscopic Investigations of the Molecular Scale Structure and Dynamics of Geologically Important Fluids and Mineral-Fluid Interfaces. Office of Scientific and Technical Information (OSTI), novembre 2008. http://dx.doi.org/10.2172/943318.

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Sabau, Adrian. Review of Thermal Contact Resistance of Flexible Graphite Materials for Thermal Interfaces in High Heat Flux Applications. Office of Scientific and Technical Information (OSTI), ottobre 2022. http://dx.doi.org/10.2172/1896991.

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Izhar, Shamay, Maureen Hanson e Nurit Firon. Expression of the Mitochondrial Locus Associated with Cytoplasmic Male Sterility in Petunia. United States Department of Agriculture, febbraio 1996. http://dx.doi.org/10.32747/1996.7604933.bard.

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Abstract (sommario):

The main goal of the proposed research was to continue the mutual investigations into the molecular basis of CMS and male fertility restoration [MRF], with the ultimate goal of understanding these phenomena in higher plants. The experiments focused on: (1) dissecting apart the complex CMS - specific mitochondrial S-Pcf locus, in order to distinguish its essential parts which cause sterility from other parts and study its molecular evolution. (2) Studying the expression of the various regions of the S-Pcf locus in fertile and sterile lines and comparing the structure and ultrastructure of sterile and fertile tissues. (3) Determine whether alteration in respiration is genetically associated with CMS. Our mutual investigations further substantiated the association between the S-Pcf locus and CMS by the findings that the fertile phenotype of a population of unstable petunia somatic hybrids which contain the S-Pcf locus, is due to the presence of multiple muclear fertility restoration genes in this group of progenies. The information obtained by our studies indicate that homologous recombination played a major role in the molecular evolution of the S-Pcf locus and the CMS trait and in the generation of mitochondrial mutations in general. Our data suggest that the CMS cytoplasm evolved by introduction of a urs-s containing sublimon into the main mitochondrial genome via homologous recombination. We have also found that the first mutation detected so far in S-Pcf is a consequence of a homologous recombination mechanism involving part of the cox2 coding sequence. In all the cases studied by us, at the molecular level, we found that fusion of two different cells caused mitochondrial DNA recombination followed by sorting out of a specific mtDNA population or sequences. This sequence of events suggested as a mechanism for the generation of novel mitochondrial genomes and the creation of new traits. The present research also provides data concerning the expression of the recombined and complex CMS-specific S-Pcf locus as compared with the expression of additional mitochondrial proteins as well as comparative histological and ultrastructural studies of CMS and fertile Petunia. Evidence is provided for differential localization of mitochondrially encoded proteins in situ at the tissue level. The similar localization patterns of Pcf and atpA may indicate that Pcf product could interfere with the functioning of the mitochondrial ATPase in a tissue undergoing meiosis and microsporogenesis. Studies of respiration in CMS and fertile Petunia lines indicate that they differe in the partitioning of electron transport through the cytochrome oxidase and alternative oxidase pathways. The data indicate that the electron flux through the two oxidase pathways differs between mitochondria from fertile and sterile Petunia lines at certain redox states of the ubiquinone pool. In summary, extensive data concerning the CMS-specific S-Pcf locus of Petunia at the DNA and protein levels as well as information concerning different biochemical activity in CMS as compared to male fertile lines have been accumulated during the three years of this project. In addition, the involvement of the homologous recombination mechanism in the evolution of mt encoded traits is emphasized.

Flux of dissolved forms of mercury across the sediment-water interface in Lahontan Reservoir, Nevada. US Geological Survey, 2002. http://dx.doi.org/10.3133/wri024138.

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