Science.gov

Sample records for accurately simulating oil

  1. Coupling geostatistics to detailed reservoir description allows better visualization and more accurate characterization/simulation of turbidite reservoirs: Elk Hills oil field, California

    SciTech Connect

    Allan, M.E.; Wilson, M.L.; Wightman, J. )

    1996-01-01

    The Elk Hills giant oilfield, located in the southern San Joaquin Valley of California, has produced 1.1 billion barrels of oil from Miocene and shallow Pliocene reservoirs. 65% of the current 64,000 BOPD production is from the pressure-supported, deeper Miocene turbidite sands. In the turbidite sands of the 31 S structure, large porosity permeability variations in the Main Body B and Western 31 S sands cause problems with the efficiency of the waterflooding. These variations have now been quantified and visualized using geostatistics. The end result is a more detailed reservoir characterization for simulation. Traditional reservoir descriptions based on marker correlations, cross-sections and mapping do not provide enough detail to capture the short-scale stratigraphic heterogeneity needed for adequate reservoir simulation. These deterministic descriptions are inadequate to tie with production data as the thinly bedded sand/shale sequences blur into a falsely homogenous picture. By studying the variability of the geologic petrophysical data vertically within each wellbore and spatially from well to well, a geostatistical reservoir description has been developed. It captures the natural variability of the sands and shales that was lacking from earlier work. These geostatistical studies allow the geologic and petrophysical characteristics to be considered in a probabilistic model. The end-product is a reservoir description that captures the variability of the reservoir sequences and can be used as a more realistic starting point for history matching and reservoir simulation.

  2. Coupling geostatistics to detailed reservoir description allows better visualization and more accurate characterization/simulation of turbidite reservoirs: Elk Hills oil field, California

    SciTech Connect

    Allan, M.E.; Wilson, M.L.; Wightman, J.

    1996-12-31

    The Elk Hills giant oilfield, located in the southern San Joaquin Valley of California, has produced 1.1 billion barrels of oil from Miocene and shallow Pliocene reservoirs. 65% of the current 64,000 BOPD production is from the pressure-supported, deeper Miocene turbidite sands. In the turbidite sands of the 31 S structure, large porosity & permeability variations in the Main Body B and Western 31 S sands cause problems with the efficiency of the waterflooding. These variations have now been quantified and visualized using geostatistics. The end result is a more detailed reservoir characterization for simulation. Traditional reservoir descriptions based on marker correlations, cross-sections and mapping do not provide enough detail to capture the short-scale stratigraphic heterogeneity needed for adequate reservoir simulation. These deterministic descriptions are inadequate to tie with production data as the thinly bedded sand/shale sequences blur into a falsely homogenous picture. By studying the variability of the geologic & petrophysical data vertically within each wellbore and spatially from well to well, a geostatistical reservoir description has been developed. It captures the natural variability of the sands and shales that was lacking from earlier work. These geostatistical studies allow the geologic and petrophysical characteristics to be considered in a probabilistic model. The end-product is a reservoir description that captures the variability of the reservoir sequences and can be used as a more realistic starting point for history matching and reservoir simulation.

  3. Next generation oil reservoir simulations

    SciTech Connect

    Joubert, W.

    1996-04-01

    This paper describes a collaborative effort between Amoco Production Company, Los Alamos National Laboratory and Cray Research Inc. to develop a next-generation massively parallel oil reservoir simulation code. The simulator, code-named Falcon, enables highly detailed simulations to be performed on a range of platforms such as the Cray T3D and T3E. The code is currently being used by Amoco to perform a sophisticated field study using multiple geostatistical realizations on a scale of 2-5 million grid blocks and 1000-2000 wells. In this paper we discuss the nature of this collaborative effort, the software design and engineering aspects of the code, parallelization experiences, and performance studies. The code will be marketed to the oil industry by a third-party independent software vendor in mid-1996.

  4. RETORT. Oil Shale Retorting Simulation

    SciTech Connect

    Eyberger, L.R.

    1992-02-26

    RETORT is a one-dimensional mathematical model for simulating the chemical and physical processes involved in the vertical retorting of a fixed or moving rubbled bed of oil shale. The model includes those processes believed to have the most important effects in either the hot-gas retorting mode or the forward combustion retorting mode. The physical processes are: axial convective transport of heat and mass, axial thermal dispersion, axial pressure drop, gas-solid heat transfer, intraparticle thermal conductivity, water evaporation and condensation, wall heat loss, and movement of shale countercurrent to flow of gas. The chemical reactions within the shale particles are: release of bound water, pyrolysis of kerogen, coking of oil, pyrolysis of char, decomposition of carbonate minerals, and gasification of residual organic carbon with CO2, H2O, and O2. The chemical reactions in the bulk-gas stream are: combustion and cracking of oil vapor, combustion of H2, CH4, CHx, and CO, and the water-gas shift. The RETORT model is meant to simulate adiabatic laboratory retorts and in situ retorts that have been prepared with fairly uniform lateral distribution of shale particle sizes, void volume, and permeability. The model`s main role is to calculate, as a function of time and axial location in the retort, the flow rate of the bulk-gas stream and the composition and temperature of both the fluid stream and the shale particles.

  5. RETORT. Oil Shale Retorting Simulation

    SciTech Connect

    Braun, R.L.

    1992-02-26

    RETORT is a one-dimensional mathematical model for simulating the chemical and physical processes involved in the vertical retorting of a fixed or moving rubbled bed of oil shale. The model includes those processes believed to have the most important effects in either the hot-gas retorting mode or the forward combustion retorting mode. The physical processes are: axial convective transport of heat and mass, axial thermal dispersion, axial pressure drop, gas-solid heat transfer, intraparticle thermal conductivity, water evaporation and condensation, wall heat loss, and movement of shale countercurrent to flow of gas. The chemical reactions within the shale particles are: release of bound water, pyrolysis of kerogen, coking of oil, pyrolysis of char, decomposition of carbonate minerals, and gasification of residual organic carbon with CO2, H2O, and O2. The chemical reactions in the bulk-gas stream are: combustion and cracking of oil vapor, combustion of H2, CH4, CHx, and CO, and the water- gas shift. The RETORT model is meant to simulate adiabatic laboratory retorts and in situ retorts that have been prepared with fairly uniform lateral distribution of shale particle sizes, void volume, and permeability. The model`s main role is to calculate, as a function of time and axial location in the retort, the flow rate of the bulk-gas stream and the composition and temperature of both the fluid stream and the shale particles.

  6. D-BRAIN: Anatomically Accurate Simulated Diffusion MRI Brain Data.

    PubMed

    Perrone, Daniele; Jeurissen, Ben; Aelterman, Jan; Roine, Timo; Sijbers, Jan; Pizurica, Aleksandra; Leemans, Alexander; Philips, Wilfried

    2016-01-01

    Diffusion Weighted (DW) MRI allows for the non-invasive study of water diffusion inside living tissues. As such, it is useful for the investigation of human brain white matter (WM) connectivity in vivo through fiber tractography (FT) algorithms. Many DW-MRI tailored restoration techniques and FT algorithms have been developed. However, it is not clear how accurately these methods reproduce the WM bundle characteristics in real-world conditions, such as in the presence of noise, partial volume effect, and a limited spatial and angular resolution. The difficulty lies in the lack of a realistic brain phantom on the one hand, and a sufficiently accurate way of modeling the acquisition-related degradation on the other. This paper proposes a software phantom that approximates a human brain to a high degree of realism and that can incorporate complex brain-like structural features. We refer to it as a Diffusion BRAIN (D-BRAIN) phantom. Also, we propose an accurate model of a (DW) MRI acquisition protocol to allow for validation of methods in realistic conditions with data imperfections. The phantom model simulates anatomical and diffusion properties for multiple brain tissue components, and can serve as a ground-truth to evaluate FT algorithms, among others. The simulation of the acquisition process allows one to include noise, partial volume effects, and limited spatial and angular resolution in the images. In this way, the effect of image artifacts on, for instance, fiber tractography can be investigated with great detail. The proposed framework enables reliable and quantitative evaluation of DW-MR image processing and FT algorithms at the level of large-scale WM structures. The effect of noise levels and other data characteristics on cortico-cortical connectivity and tractography-based grey matter parcellation can be investigated as well. PMID:26930054

  7. A New Multiscale Technique for Time-Accurate Geophysics Simulations

    NASA Astrophysics Data System (ADS)

    Omelchenko, Y. A.; Karimabadi, H.

    2006-12-01

    Large-scale geophysics systems are frequently described by multiscale reactive flow models (e.g., wildfire and climate models, multiphase flows in porous rocks, etc.). Accurate and robust simulations of such systems by traditional time-stepping techniques face a formidable computational challenge. Explicit time integration suffers from global (CFL and accuracy) timestep restrictions due to inhomogeneous convective and diffusion processes, as well as closely coupled physical and chemical reactions. Application of adaptive mesh refinement (AMR) to such systems may not be always sufficient since its success critically depends on a careful choice of domain refinement strategy. On the other hand, implicit and timestep-splitting integrations may result in a considerable loss of accuracy when fast transients in the solution become important. To address this issue, we developed an alternative explicit approach to time-accurate integration of such systems: Discrete-Event Simulation (DES). DES enables asynchronous computation by automatically adjusting the CPU resources in accordance with local timescales. This is done by encapsulating flux- conservative updates of numerical variables in the form of events, whose execution and synchronization is explicitly controlled by imposing accuracy and causality constraints. As a result, at each time step DES self- adaptively updates only a fraction of the global system state, which eliminates unnecessary computation of inactive elements. DES can be naturally combined with various mesh generation techniques. The event-driven paradigm results in robust and fast simulation codes, which can be efficiently parallelized via a new preemptive event processing (PEP) technique. We discuss applications of this novel technology to time-dependent diffusion-advection-reaction and CFD models representative of various geophysics applications.

  8. Progress in fast, accurate multi-scale climate simulations

    SciTech Connect

    Collins, W. D.; Johansen, H.; Evans, K. J.; Woodward, C. S.; Caldwell, P. M.

    2015-06-01

    We present a survey of physical and computational techniques that have the potential to contribute to the next generation of high-fidelity, multi-scale climate simulations. Examples of the climate science problems that can be investigated with more depth with these computational improvements include the capture of remote forcings of localized hydrological extreme events, an accurate representation of cloud features over a range of spatial and temporal scales, and parallel, large ensembles of simulations to more effectively explore model sensitivities and uncertainties. Numerical techniques, such as adaptive mesh refinement, implicit time integration, and separate treatment of fast physical time scales are enabling improved accuracy and fidelity in simulation of dynamics and allowing more complete representations of climate features at the global scale. At the same time, partnerships with computer science teams have focused on taking advantage of evolving computer architectures such as many-core processors and GPUs. As a result, approaches which were previously considered prohibitively costly have become both more efficient and scalable. In combination, progress in these three critical areas is poised to transform climate modeling in the coming decades.

  9. Progress in fast, accurate multi-scale climate simulations

    DOE PAGES

    Collins, W. D.; Johansen, H.; Evans, K. J.; Woodward, C. S.; Caldwell, P. M.

    2015-06-01

    We present a survey of physical and computational techniques that have the potential to contribute to the next generation of high-fidelity, multi-scale climate simulations. Examples of the climate science problems that can be investigated with more depth with these computational improvements include the capture of remote forcings of localized hydrological extreme events, an accurate representation of cloud features over a range of spatial and temporal scales, and parallel, large ensembles of simulations to more effectively explore model sensitivities and uncertainties. Numerical techniques, such as adaptive mesh refinement, implicit time integration, and separate treatment of fast physical time scales are enablingmore » improved accuracy and fidelity in simulation of dynamics and allowing more complete representations of climate features at the global scale. At the same time, partnerships with computer science teams have focused on taking advantage of evolving computer architectures such as many-core processors and GPUs. As a result, approaches which were previously considered prohibitively costly have become both more efficient and scalable. In combination, progress in these three critical areas is poised to transform climate modeling in the coming decades.« less

  10. Progress in Fast, Accurate Multi-scale Climate Simulations

    SciTech Connect

    Collins, William D; Johansen, Hans; Evans, Katherine J; Woodward, Carol S.; Caldwell, Peter

    2015-01-01

    We present a survey of physical and computational techniques that have the potential to con- tribute to the next generation of high-fidelity, multi-scale climate simulations. Examples of the climate science problems that can be investigated with more depth include the capture of remote forcings of localized hydrological extreme events, an accurate representation of cloud features over a range of spatial and temporal scales, and parallel, large ensembles of simulations to more effectively explore model sensitivities and uncertainties. Numerical techniques, such as adaptive mesh refinement, implicit time integration, and separate treatment of fast physical time scales are enabling improved accuracy and fidelity in simulation of dynamics and allow more complete representations of climate features at the global scale. At the same time, part- nerships with computer science teams have focused on taking advantage of evolving computer architectures, such as many-core processors and GPUs, so that these approaches which were previously considered prohibitively costly have become both more efficient and scalable. In combination, progress in these three critical areas is poised to transform climate modeling in the coming decades.

  11. Chewing simulation with a physically accurate deformable model.

    PubMed

    Pascale, Andra Maria; Ruge, Sebastian; Hauth, Steffen; Kordaß, Bernd; Linsen, Lars

    2015-01-01

    Nowadays, CAD/CAM software is being used to compute the optimal shape and position of a new tooth model meant for a patient. With this possible future application in mind, we present in this article an independent and stand-alone interactive application that simulates the human chewing process and the deformation it produces in the food substrate. Chewing motion sensors are used to produce an accurate representation of the jaw movement. The substrate is represented by a deformable elastic model based on the finite linear elements method, which preserves physical accuracy. Collision detection based on spatial partitioning is used to calculate the forces that are acting on the deformable model. Based on the calculated information, geometry elements are added to the scene to enhance the information available for the user. The goal of the simulation is to present a complete scene to the dentist, highlighting the points where the teeth came into contact with the substrate and giving information about how much force acted at these points, which therefore makes it possible to indicate whether the tooth is being used incorrectly in the mastication process. Real-time interactivity is desired and achieved within limits, depending on the complexity of the employed geometric models. The presented simulation is a first step towards the overall project goal of interactively optimizing tooth position and shape under the investigation of a virtual chewing process using real patient data (Fig 1). PMID:26389135

  12. How Accurate Are Transition States from Simulations of Enzymatic Reactions?

    PubMed Central

    2015-01-01

    The rate expression of traditional transition state theory (TST) assumes no recrossing of the transition state (TS) and thermal quasi-equilibrium between the ground state and the TS. Currently, it is not well understood to what extent these assumptions influence the nature of the activated complex obtained in traditional TST-based simulations of processes in the condensed phase in general and in enzymes in particular. Here we scrutinize these assumptions by characterizing the TSs for hydride transfer catalyzed by the enzyme Escherichia coli dihydrofolate reductase obtained using various simulation approaches. Specifically, we compare the TSs obtained with common TST-based methods and a dynamics-based method. Using a recently developed accurate hybrid quantum mechanics/molecular mechanics potential, we find that the TST-based and dynamics-based methods give considerably different TS ensembles. This discrepancy, which could be due equilibrium solvation effects and the nature of the reaction coordinate employed and its motion, raises major questions about how to interpret the TSs determined by common simulation methods. We conclude that further investigation is needed to characterize the impact of various TST assumptions on the TS phase-space ensemble and on the reaction kinetics. PMID:24860275

  13. Accurate simulation dynamics of microscopic filaments using ``caterpillar'' Oseen hydrodynamics

    NASA Astrophysics Data System (ADS)

    Bailey, A. G.; Lowe, C. P.; Pagonabarraga, I.; Lagomarsino, M. Cosentino

    2009-10-01

    Microscopic semiflexible filaments suspended in a viscous fluid are widely encountered in biophysical problems. The classic example is the flagella used by microorganisms to generate propulsion. Simulating the dynamics of these filaments numerically is complicated because of the coupling between the motion of the filament and that of the surrounding fluid. An attractive idea is to simplify this coupling by modeling the fluid motion by using Stokeslets distributed at equal intervals along the model filament. We show that, with an appropriate choice of the hydrodynamic radii, one can recover accurate hydrodynamic behavior of a filament with a finite cross section without requiring an explicit surface. This is true, however, only if the hydrodynamic radii take specific values and that they differ in the parallel and perpendicular directions leading to a caterpillarlike hydrodynamic shape. Having demonstrated this, we use the model to compare with analytic theory of filament deformation and rotation in the small deformation limit. Generalization of the methodology, including application to simulations using the Rotne-Prager tensor, is discussed.

  14. Symphony: A Framework for Accurate and Holistic WSN Simulation

    PubMed Central

    Riliskis, Laurynas; Osipov, Evgeny

    2015-01-01

    Research on wireless sensor networks has progressed rapidly over the last decade, and these technologies have been widely adopted for both industrial and domestic uses. Several operating systems have been developed, along with a multitude of network protocols for all layers of the communication stack. Industrial Wireless Sensor Network (WSN) systems must satisfy strict criteria and are typically more complex and larger in scale than domestic systems. Together with the non-deterministic behavior of network hardware in real settings, this greatly complicates the debugging and testing of WSN functionality. To facilitate the testing, validation, and debugging of large-scale WSN systems, we have developed a simulation framework that accurately reproduces the processes that occur inside real equipment, including both hardware- and software-induced delays. The core of the framework consists of a virtualized operating system and an emulated hardware platform that is integrated with the general purpose network simulator ns-3. Our framework enables the user to adjust the real code base as would be done in real deployments and also to test the boundary effects of different hardware components on the performance of distributed applications and protocols. Additionally we have developed a clock emulator with several different skew models and a component that handles sensory data feeds. The new framework should substantially shorten WSN application development cycles. PMID:25723144

  15. Symphony: a framework for accurate and holistic WSN simulation.

    PubMed

    Riliskis, Laurynas; Osipov, Evgeny

    2015-01-01

    Research on wireless sensor networks has progressed rapidly over the last decade, and these technologies have been widely adopted for both industrial and domestic uses. Several operating systems have been developed, along with a multitude of network protocols for all layers of the communication stack. Industrial Wireless Sensor Network (WSN) systems must satisfy strict criteria and are typically more complex and larger in scale than domestic systems. Together with the non-deterministic behavior of network hardware in real settings, this greatly complicates the debugging and testing of WSN functionality. To facilitate the testing, validation, and debugging of large-scale WSN systems, we have developed a simulation framework that accurately reproduces the processes that occur inside real equipment, including both hardware- and software-induced delays. The core of the framework consists of a virtualized operating system and an emulated hardware platform that is integrated with the general purpose network simulator ns-3. Our framework enables the user to adjust the real code base as would be done in real deployments and also to test the boundary effects of different hardware components on the performance of distributed applications and protocols. Additionally we have developed a clock emulator with several different skew models and a component that handles sensory data feeds. The new framework should substantially shorten WSN application development cycles.

  16. Accurate bs and w testing important for crude-oil custody transfer

    SciTech Connect

    Williams, J. )

    1990-11-12

    This paper discusses how monitoring crude-oil sediment and water content at the field production site is essential in accurate crude-oil custody transfer operations. This is accomplished by manual methods, or on-line devices like capacitance, density, or energy-absorption analyzers. For custody-transfer purposes, sediment and water is determined by a test which follows one of the API manuals of petroleum measurement standards (MPMS). Typically, this test is conducted in the field by the field centrifuge method which, if performed properly, yields very accurate results. Laboratory tests can be performed, but sample handling becomes even more critical.

  17. Fast and Accurate Simulation of the Cray XMT Multithreaded Supercomputer

    SciTech Connect

    Villa, Oreste; Tumeo, Antonino; Secchi, Simone; Manzano Franco, Joseph B.

    2012-12-31

    Irregular applications, such as data mining and analysis or graph-based computations, show unpredictable memory/network access patterns and control structures. Highly multithreaded architectures with large processor counts, like the Cray MTA-1, MTA-2 and XMT, appear to address their requirements better than commodity clusters. However, the research on highly multithreaded systems is currently limited by the lack of adequate architectural simulation infrastructures due to issues such as size of the machines, memory footprint, simulation speed, accuracy and customization. At the same time, Shared-memory MultiProcessors (SMPs) with multi-core processors have become an attractive platform to simulate large scale machines. In this paper, we introduce a cycle-level simulator of the highly multithreaded Cray XMT supercomputer. The simulator runs unmodified XMT applications. We discuss how we tackled the challenges posed by its development, detailing the techniques introduced to make the simulation as fast as possible while maintaining a high accuracy. By mapping XMT processors (ThreadStorm with 128 hardware threads) to host computing cores, the simulation speed remains constant as the number of simulated processors increases, up to the number of available host cores. The simulator supports zero-overhead switching among different accuracy levels at run-time and includes a network model that takes into account contention. On a modern 48-core SMP host, our infrastructure simulates a large set of irregular applications 500 to 2000 times slower than real time when compared to a 128-processor XMT, while remaining within 10\\% of accuracy. Emulation is only from 25 to 200 times slower than real time.

  18. Massively Parallel Processing for Fast and Accurate Stamping Simulations

    NASA Astrophysics Data System (ADS)

    Gress, Jeffrey J.; Xu, Siguang; Joshi, Ramesh; Wang, Chuan-tao; Paul, Sabu

    2005-08-01

    The competitive automotive market drives automotive manufacturers to speed up the vehicle development cycles and reduce the lead-time. Fast tooling development is one of the key areas to support fast and short vehicle development programs (VDP). In the past ten years, the stamping simulation has become the most effective validation tool in predicting and resolving all potential formability and quality problems before the dies are physically made. The stamping simulation and formability analysis has become an critical business segment in GM math-based die engineering process. As the simulation becomes as one of the major production tools in engineering factory, the simulation speed and accuracy are the two of the most important measures for stamping simulation technology. The speed and time-in-system of forming analysis becomes an even more critical to support the fast VDP and tooling readiness. Since 1997, General Motors Die Center has been working jointly with our software vendor to develop and implement a parallel version of simulation software for mass production analysis applications. By 2001, this technology was matured in the form of distributed memory processing (DMP) of draw die simulations in a networked distributed memory computing environment. In 2004, this technology was refined to massively parallel processing (MPP) and extended to line die forming analysis (draw, trim, flange, and associated spring-back) running on a dedicated computing environment. The evolution of this technology and the insight gained through the implementation of DM0P/MPP technology as well as performance benchmarks are discussed in this publication.

  19. The FLUKA Code: An Accurate Simulation Tool for Particle Therapy

    PubMed Central

    Battistoni, Giuseppe; Bauer, Julia; Boehlen, Till T.; Cerutti, Francesco; Chin, Mary P. W.; Dos Santos Augusto, Ricardo; Ferrari, Alfredo; Ortega, Pablo G.; Kozłowska, Wioletta; Magro, Giuseppe; Mairani, Andrea; Parodi, Katia; Sala, Paola R.; Schoofs, Philippe; Tessonnier, Thomas; Vlachoudis, Vasilis

    2016-01-01

    Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both 4He and 12C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth–dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features. PMID:27242956

  20. The FLUKA Code: An Accurate Simulation Tool for Particle Therapy.

    PubMed

    Battistoni, Giuseppe; Bauer, Julia; Boehlen, Till T; Cerutti, Francesco; Chin, Mary P W; Dos Santos Augusto, Ricardo; Ferrari, Alfredo; Ortega, Pablo G; Kozłowska, Wioletta; Magro, Giuseppe; Mairani, Andrea; Parodi, Katia; Sala, Paola R; Schoofs, Philippe; Tessonnier, Thomas; Vlachoudis, Vasilis

    2016-01-01

    Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both (4)He and (12)C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth-dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features. PMID:27242956

  1. Accurate, practical simulation of satellite infrared radiometer spectral data

    SciTech Connect

    Sullivan, T.J.

    1982-09-01

    This study's purpose is to determine whether a relatively simple random band model formulation of atmospheric radiation transfer in the infrared region can provide valid simulations of narrow interval satellite-borne infrared sounder system data. Detailed ozonesondes provide the pertinent atmospheric information and sets of calibrated satellite measurements provide the validation. High resolution line-by-line model calculations are included to complete the evaluation.

  2. Accurate numerical simulation of short fiber optical parametric amplifiers.

    PubMed

    Marhic, M E; Rieznik, A A; Kalogerakis, G; Braimiotis, C; Fragnito, H L; Kazovsky, L G

    2008-03-17

    We improve the accuracy of numerical simulations for short fiber optical parametric amplifiers (OPAs). Instead of using the usual coarse-step method, we adopt a model for birefringence and dispersion which uses fine-step variations of the parameters. We also improve the split-step Fourier method by exactly treating the nonlinear ellipse rotation terms. We find that results obtained this way for two-pump OPAs can be significantly different from those obtained by using the usual coarse-step fiber model, and/or neglecting ellipse rotation terms.

  3. Simulation model accurately estimates total dietary iodine intake.

    PubMed

    Verkaik-Kloosterman, Janneke; van 't Veer, Pieter; Ocké, Marga C

    2009-07-01

    One problem with estimating iodine intake is the lack of detailed data about the discretionary use of iodized kitchen salt and iodization of industrially processed foods. To be able to take into account these uncertainties in estimating iodine intake, a simulation model combining deterministic and probabilistic techniques was developed. Data from the Dutch National Food Consumption Survey (1997-1998) and an update of the Food Composition database were used to simulate 3 different scenarios: Dutch iodine legislation until July 2008, Dutch iodine legislation after July 2008, and a potential future situation. Results from studies measuring iodine excretion during the former legislation are comparable with the iodine intakes estimated with our model. For both former and current legislation, iodine intake was adequate for a large part of the Dutch population, but some young children (<5%) were at risk of intakes that were too low. In the scenario of a potential future situation using lower salt iodine levels, the percentage of the Dutch population with intakes that were too low increased (almost 10% of young children). To keep iodine intakes adequate, salt iodine levels should not be decreased, unless many more foods will contain iodized salt. Our model should be useful in predicting the effects of food reformulation or fortification on habitual nutrient intakes.

  4. Accurate Position Sensing of Defocused Beams Using Simulated Beam Templates

    SciTech Connect

    Awwal, A; Candy, J; Haynam, C; Widmayer, C; Bliss, E; Burkhart, S

    2004-09-29

    In position detection using matched filtering one is faced with the challenge of determining the best position in the presence of distortions such as defocus and diffraction noise. This work evaluates the performance of simulated defocused images as the template against the real defocused beam. It was found that an amplitude modulated phase-only filter is better equipped to deal with real defocused images that suffer from diffraction noise effects resulting in a textured spot intensity pattern. It is shown that the there is a tradeoff of performance dependent upon the type and size of the defocused image. A novel automated system was developed that can automatically select the right template type and size. Results of this automation for real defocused images are presented.

  5. Accurate direct Eulerian simulation of dynamic elastic-plastic flow

    SciTech Connect

    Kamm, James R; Walter, John W

    2009-01-01

    The simulation of dynamic, large strain deformation is an important, difficult, and unsolved computational challenge. Existing Eulerian schemes for dynamic material response are plagued by unresolved issues. We present a new scheme for the first-order system of elasto-plasticity equations in the Eulerian frame. This system has an intrinsic constraint on the inverse deformation gradient. Standard Godunov schemes do not satisfy this constraint. The method of Flux Distributions (FD) was devised to discretely enforce such constraints for numerical schemes with cell-centered variables. We describe a Flux Distribution approach that enforces the inverse deformation gradient constraint. As this approach is new and novel, we do not yet have numerical results to validate our claims. This paper is the first installment of our program to develop this new method.

  6. Toward the Accurate Simulation of Two-Dimensional Electronic Spectra

    NASA Astrophysics Data System (ADS)

    Giussani, Angelo; Nenov, Artur; Segarra-Martí, Javier; Jaiswal, Vishal K.; Rivalta, Ivan; Dumont, Elise; Mukamel, Shaul; Garavelli, Marco

    2015-06-01

    Two-dimensional pump-probe electronic spectroscopy is a powerful technique able to provide both high spectral and temporal resolution, allowing the analysis of ultrafast complex reactions occurring via complementary pathways by the identification of decay-specific fingerprints. [1-2] The understanding of the origin of the experimentally recorded signals in a two-dimensional electronic spectrum requires the characterization of the electronic states involved in the electronic transitions photoinduced by the pump/probe pulses in the experiment. Such a goal constitutes a considerable computational challenge, since up to 100 states need to be described, for which state-of-the-art methods as RASSCF and RASPT2 have to be wisely employed. [3] With the present contribution, the main features and potentialities of two-dimensional electronic spectroscopy are presented, together with the machinery in continuous development in our groups in order to compute two-dimensional electronic spectra. The results obtained using different level of theory and simulations are shown, bringing as examples the computed two-dimensional electronic spectra for some specific cases studied. [2-4] [1] Rivalta I, Nenov A, Cerullo G, Mukamel S, Garavelli M, Int. J. Quantum Chem., 2014, 114, 85 [2] Nenov A, Segarra-Martí J, Giussani A, Conti I, Rivalta I, Dumont E, Jaiswal V K, Altavilla S, Mukamel S, Garavelli M, Faraday Discuss. 2015, DOI: 10.1039/C4FD00175C [3] Nenov A, Giussani A, Segarra-Martí J, Jaiswal V K, Rivalta I, Cerullo G, Mukamel S, Garavelli M, J. Chem. Phys. submitted [4] Nenov A, Giussani A, Fingerhut B P, Rivalta I, Dumont E, Mukamel S, Garavelli M, Phys. Chem. Chem. Phys. Submitted [5] Krebs N, Pugliesi I, Hauer J, Riedle E, New J. Phys., 2013,15, 08501

  7. Accurate Behavioral Simulator of All-Digital Time-Domain Smart Temperature Sensors by Using SIMULINK.

    PubMed

    Chen, Chun-Chi; Chen, Chao-Lieh; Lin, You-Ting

    2016-01-01

    This study proposes a new behavioral simulator that uses SIMULINK for all-digital CMOS time-domain smart temperature sensors (TDSTSs) for performing rapid and accurate simulations. Inverter-based TDSTSs offer the benefits of low cost and simple structure for temperature-to-digital conversion and have been developed. Typically, electronic design automation tools, such as HSPICE, are used to simulate TDSTSs for performance evaluations. However, such tools require extremely long simulation time and complex procedures to analyze the results and generate figures. In this paper, we organize simple but accurate equations into a temperature-dependent model (TDM) by which the TDSTSs evaluate temperature behavior. Furthermore, temperature-sensing models of a single CMOS NOT gate were devised using HSPICE simulations. Using the TDM and these temperature-sensing models, a novel simulator in SIMULINK environment was developed to substantially accelerate the simulation and simplify the evaluation procedures. Experiments demonstrated that the simulation results of the proposed simulator have favorable agreement with those obtained from HSPICE simulations, showing that the proposed simulator functions successfully. This is the first behavioral simulator addressing the rapid simulation of TDSTSs. PMID:27509507

  8. Accurate Behavioral Simulator of All-Digital Time-Domain Smart Temperature Sensors by Using SIMULINK

    PubMed Central

    Chen, Chun-Chi; Chen, Chao-Lieh; Lin, You-Ting

    2016-01-01

    This study proposes a new behavioral simulator that uses SIMULINK for all-digital CMOS time-domain smart temperature sensors (TDSTSs) for performing rapid and accurate simulations. Inverter-based TDSTSs offer the benefits of low cost and simple structure for temperature-to-digital conversion and have been developed. Typically, electronic design automation tools, such as HSPICE, are used to simulate TDSTSs for performance evaluations. However, such tools require extremely long simulation time and complex procedures to analyze the results and generate figures. In this paper, we organize simple but accurate equations into a temperature-dependent model (TDM) by which the TDSTSs evaluate temperature behavior. Furthermore, temperature-sensing models of a single CMOS NOT gate were devised using HSPICE simulations. Using the TDM and these temperature-sensing models, a novel simulator in SIMULINK environment was developed to substantially accelerate the simulation and simplify the evaluation procedures. Experiments demonstrated that the simulation results of the proposed simulator have favorable agreement with those obtained from HSPICE simulations, showing that the proposed simulator functions successfully. This is the first behavioral simulator addressing the rapid simulation of TDSTSs. PMID:27509507

  9. An accurate simulation model for single-photon avalanche diodes including important statistical effects

    NASA Astrophysics Data System (ADS)

    Qiuyang, He; Yue, Xu; Feifei, Zhao

    2013-10-01

    An accurate and complete circuit simulation model for single-photon avalanche diodes (SPADs) is presented. The derived model is not only able to simulate the static DC and dynamic AC behaviors of an SPAD operating in Geiger-mode, but also can emulate the second breakdown and the forward bias behaviors. In particular, it considers important statistical effects, such as dark-counting and after-pulsing phenomena. The developed model is implemented using the Verilog-A description language and can be directly performed in commercial simulators such as Cadence Spectre. The Spectre simulation results give a very good agreement with the experimental results reported in the open literature. This model shows a high simulation accuracy and very fast simulation rate.

  10. Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

    2015-01-01

    Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

  11. Fast, Accurate RF Propagation Modeling and Simulation Tool for Highly Cluttered Environments

    SciTech Connect

    Kuruganti, Phani Teja

    2007-01-01

    As network centric warfare and distributed operations paradigms unfold, there is a need for robust, fast wireless network deployment tools. These tools must take into consideration the terrain of the operating theater, and facilitate specific modeling of end to end network performance based on accurate RF propagation predictions. It is well known that empirical models can not provide accurate, site specific predictions of radio channel behavior. In this paper an event-driven wave propagation simulation is proposed as a computationally efficient technique for predicting critical propagation characteristics of RF signals in cluttered environments. Convincing validation and simulator performance studies confirm the suitability of this method for indoor and urban area RF channel modeling. By integrating our RF propagation prediction tool, RCSIM, with popular packetlevel network simulators, we are able to construct an end to end network analysis tool for wireless networks operated in built-up urban areas.

  12. Liquid propellant rocket engine combustion simulation with a time-accurate CFD method

    NASA Technical Reports Server (NTRS)

    Chen, Y. S.; Shang, H. M.; Liaw, Paul; Hutt, J.

    1993-01-01

    Time-accurate computational fluid dynamics (CFD) algorithms are among the basic requirements as an engineering or research tool for realistic simulations of transient combustion phenomena, such as combustion instability, transient start-up, etc., inside the rocket engine combustion chamber. A time-accurate pressure based method is employed in the FDNS code for combustion model development. This is in connection with other program development activities such as spray combustion model development and efficient finite-rate chemistry solution method implementation. In the present study, a second-order time-accurate time-marching scheme is employed. For better spatial resolutions near discontinuities (e.g., shocks, contact discontinuities), a 3rd-order accurate TVD scheme for modeling the convection terms is implemented in the FDNS code. Necessary modification to the predictor/multi-corrector solution algorithm in order to maintain time-accurate wave propagation is also investigated. Benchmark 1-D and multidimensional test cases, which include the classical shock tube wave propagation problems, resonant pipe test case, unsteady flow development of a blast tube test case, and H2/O2 rocket engine chamber combustion start-up transient simulation, etc., are investigated to validate and demonstrate the accuracy and robustness of the present numerical scheme and solution algorithm.

  13. Accurate and precise determination of critical properties from Gibbs ensemble Monte Carlo simulations

    SciTech Connect

    Dinpajooh, Mohammadhasan; Bai, Peng; Allan, Douglas A.; Siepmann, J. Ilja

    2015-09-21

    Since the seminal paper by Panagiotopoulos [Mol. Phys. 61, 813 (1997)], the Gibbs ensemble Monte Carlo (GEMC) method has been the most popular particle-based simulation approach for the computation of vapor–liquid phase equilibria. However, the validity of GEMC simulations in the near-critical region has been questioned because rigorous finite-size scaling approaches cannot be applied to simulations with fluctuating volume. Valleau [Mol. Simul. 29, 627 (2003)] has argued that GEMC simulations would lead to a spurious overestimation of the critical temperature. More recently, Patel et al. [J. Chem. Phys. 134, 024101 (2011)] opined that the use of analytical tail corrections would be problematic in the near-critical region. To address these issues, we perform extensive GEMC simulations for Lennard-Jones particles in the near-critical region varying the system size, the overall system density, and the cutoff distance. For a system with N = 5500 particles, potential truncation at 8σ and analytical tail corrections, an extrapolation of GEMC simulation data at temperatures in the range from 1.27 to 1.305 yields T{sub c} = 1.3128 ± 0.0016, ρ{sub c} = 0.316 ± 0.004, and p{sub c} = 0.1274 ± 0.0013 in excellent agreement with the thermodynamic limit determined by Potoff and Panagiotopoulos [J. Chem. Phys. 109, 10914 (1998)] using grand canonical Monte Carlo simulations and finite-size scaling. Critical properties estimated using GEMC simulations with different overall system densities (0.296 ≤ ρ{sub t} ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using r{sub cut} = 3.5σ yield T{sub c} and p{sub c} that are higher by 0.2% and 1.4% than simulations with r{sub cut} = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that r{sub cut} = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard

  14. Accurate and precise determination of critical properties from Gibbs ensemble Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Dinpajooh, Mohammadhasan; Bai, Peng; Allan, Douglas A.; Siepmann, J. Ilja

    2015-09-01

    Since the seminal paper by Panagiotopoulos [Mol. Phys. 61, 813 (1997)], the Gibbs ensemble Monte Carlo (GEMC) method has been the most popular particle-based simulation approach for the computation of vapor-liquid phase equilibria. However, the validity of GEMC simulations in the near-critical region has been questioned because rigorous finite-size scaling approaches cannot be applied to simulations with fluctuating volume. Valleau [Mol. Simul. 29, 627 (2003)] has argued that GEMC simulations would lead to a spurious overestimation of the critical temperature. More recently, Patel et al. [J. Chem. Phys. 134, 024101 (2011)] opined that the use of analytical tail corrections would be problematic in the near-critical region. To address these issues, we perform extensive GEMC simulations for Lennard-Jones particles in the near-critical region varying the system size, the overall system density, and the cutoff distance. For a system with N = 5500 particles, potential truncation at 8σ and analytical tail corrections, an extrapolation of GEMC simulation data at temperatures in the range from 1.27 to 1.305 yields Tc = 1.3128 ± 0.0016, ρc = 0.316 ± 0.004, and pc = 0.1274 ± 0.0013 in excellent agreement with the thermodynamic limit determined by Potoff and Panagiotopoulos [J. Chem. Phys. 109, 10914 (1998)] using grand canonical Monte Carlo simulations and finite-size scaling. Critical properties estimated using GEMC simulations with different overall system densities (0.296 ≤ ρt ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using rcut = 3.5σ yield Tc and pc that are higher by 0.2% and 1.4% than simulations with rcut = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that rcut = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard-core square-well particles with various ranges of the

  15. CgWind: A high-order accurate simulation tool for wind turbines and wind farms

    SciTech Connect

    Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A

    2010-02-22

    CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

  16. Improving light propagation Monte Carlo simulations with accurate 3D modeling of skin tissue

    SciTech Connect

    Paquit, Vincent C; Price, Jeffery R; Meriaudeau, Fabrice; Tobin Jr, Kenneth William

    2008-01-01

    In this paper, we present a 3D light propagation model to simulate multispectral reflectance images of large skin surface areas. In particular, we aim to simulate more accurately the effects of various physiological properties of the skin in the case of subcutaneous vein imaging compared to existing models. Our method combines a Monte Carlo light propagation model, a realistic three-dimensional model of the skin using parametric surfaces and a vision system for data acquisition. We describe our model in detail, present results from the Monte Carlo modeling and compare our results with those obtained with a well established Monte Carlo model and with real skin reflectance images.

  17. Time-Accurate Simulations and Acoustic Analysis of Slat Free-Shear-Layer. Part 2

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Singer, Bart A.; Lockard, David P.

    2002-01-01

    Unsteady computational simulations of a multi-element, high-lift configuration are performed. Emphasis is placed on accurate spatiotemporal resolution of the free shear layer in the slat-cove region. The excessive dissipative effects of the turbulence model, so prevalent in previous simulations, are circumvented by switching off the turbulence-production term in the slat cove region. The justifications and physical arguments for taking such a step are explained in detail. The removal of this excess damping allows the shear layer to amplify large-scale structures, to achieve a proper non-linear saturation state, and to permit vortex merging. The large-scale disturbances are self-excited, and unlike our prior fully turbulent simulations, no external forcing of the shear layer is required. To obtain the farfield acoustics, the Ffowcs Williams and Hawkings equation is evaluated numerically using the simulated time-accurate flow data. The present comparison between the computed and measured farfield acoustic spectra shows much better agreement for the amplitude and frequency content than past calculations. The effect of the angle-of-attack on the slat's flow features radiated acoustic field are also simulated presented.

  18. Computational Simulation of Submarine Oil Spill with Current

    NASA Astrophysics Data System (ADS)

    Li, Wei; Pang, Yongjie; Li, Hongwei

    Nowadays, the oil spill models are usually based on the sea surface and few of them are for submarine oil spill. Therefore, the simulation for submarine pipeline oil spill is discussed by FLUENT in this paper to forecast the trajectory of oil. The coupling of pressure and velocity under unsteady-state condition is solved by pressure implicit with splitting of operators algorithm, and the boundary condition of nonlinear free surface is solved by volume of fluid. The simulation of oil particles motion is carried out. Furthermore, the quantity and trajectory of spilled oil under different operating pressure and current velocity are compared and analyzed. The results show that the submarine diffusion scope of spilled oil is smaller with larger operating pressure or lower current velocity.

  19. Accurate and efficient halo-based galaxy clustering modelling with simulations

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng; Guo, Hong

    2016-06-01

    Small- and intermediate-scale galaxy clustering can be used to establish the galaxy-halo connection to study galaxy formation and evolution and to tighten constraints on cosmological parameters. With the increasing precision of galaxy clustering measurements from ongoing and forthcoming large galaxy surveys, accurate models are required to interpret the data and extract relevant information. We introduce a method based on high-resolution N-body simulations to accurately and efficiently model the galaxy two-point correlation functions (2PCFs) in projected and redshift spaces. The basic idea is to tabulate all information of haloes in the simulations necessary for computing the galaxy 2PCFs within the framework of halo occupation distribution or conditional luminosity function. It is equivalent to populating galaxies to dark matter haloes and using the mock 2PCF measurements as the model predictions. Besides the accurate 2PCF calculations, the method is also fast and therefore enables an efficient exploration of the parameter space. As an example of the method, we decompose the redshift-space galaxy 2PCF into different components based on the type of galaxy pairs and show the redshift-space distortion effect in each component. The generalizations and limitations of the method are discussed.

  20. Recommendations for Achieving Accurate Numerical Simulation of Tip Clearance Flows in Transonic Compressor Rotors

    NASA Technical Reports Server (NTRS)

    VanZante, Dale E.; Strazisar, Anthony J.; Wood, Jerry R,; Hathaway, Michael D.; Okiishi, Theodore H.

    2000-01-01

    The tip clearance flows of transonic compressor rotors are important because they have a significant impact on rotor and stage performance. While numerical simulations of these flows are quite sophisticated. they are seldom verified through rigorous comparisons of numerical and measured data because these kinds of measurements are rare in the detail necessary to be useful in high-speed machines. In this paper we compare measured tip clearance flow details (e.g. trajectory and radial extent) with corresponding data obtained from a numerical simulation. Recommendations for achieving accurate numerical simulation of tip clearance flows are presented based on this comparison. Laser Doppler Velocimeter (LDV) measurements acquired in a transonic compressor rotor, NASA Rotor 35, are used. The tip clearance flow field of this transonic rotor was simulated using a Navier-Stokes turbomachinery solver that incorporates an advanced k-epsilon turbulence model derived for flows that are not in local equilibrium. Comparison between measured and simulated results indicates that simulation accuracy is primarily dependent upon the ability of the numerical code to resolve important details of a wall-bounded shear layer formed by the relative motion between the over-tip leakage flow and the shroud wall. A simple method is presented for determining the strength of this shear layer.

  1. Development of modified cable models to simulate accurate neuronal active behaviors.

    PubMed

    Elbasiouny, Sherif M

    2014-12-01

    In large network and single three-dimensional (3-D) neuron simulations, high computing speed dictates using reduced cable models to simulate neuronal firing behaviors. However, these models are unwarranted under active conditions and lack accurate representation of dendritic active conductances that greatly shape neuronal firing. Here, realistic 3-D (R3D) models (which contain full anatomical details of dendrites) of spinal motoneurons were systematically compared with their reduced single unbranched cable (SUC, which reduces the dendrites to a single electrically equivalent cable) counterpart under passive and active conditions. The SUC models matched the R3D model's passive properties but failed to match key active properties, especially active behaviors originating from dendrites. For instance, persistent inward currents (PIC) hysteresis, frequency-current (FI) relationship secondary range slope, firing hysteresis, plateau potential partial deactivation, staircase currents, synaptic current transfer ratio, and regional FI relationships were not accurately reproduced by the SUC models. The dendritic morphology oversimplification and lack of dendritic active conductances spatial segregation in the SUC models caused significant underestimation of those behaviors. Next, SUC models were modified by adding key branching features in an attempt to restore their active behaviors. The addition of primary dendritic branching only partially restored some active behaviors, whereas the addition of secondary dendritic branching restored most behaviors. Importantly, the proposed modified models successfully replicated the active properties without sacrificing model simplicity, making them attractive candidates for running R3D single neuron and network simulations with accurate firing behaviors. The present results indicate that using reduced models to examine PIC behaviors in spinal motoneurons is unwarranted.

  2. Fast and accurate simulations of diffusion-weighted MRI signals for the evaluation of acquisition sequences

    NASA Astrophysics Data System (ADS)

    Rensonnet, Gaëtan; Jacobs, Damien; Macq, Benoît.; Taquet, Maxime

    2016-03-01

    Diffusion-weighted magnetic resonance imaging (DW-MRI) is a powerful tool to probe the diffusion of water through tissues. Through the application of magnetic gradients of appropriate direction, intensity and duration constituting the acquisition parameters, information can be retrieved about the underlying microstructural organization of the brain. In this context, an important and open question is to determine an optimal sequence of such acquisition parameters for a specific purpose. The use of simulated DW-MRI data for a given microstructural configuration provides a convenient and efficient way to address this problem. We first present a novel hybrid method for the synthetic simulation of DW-MRI signals that combines analytic expressions in simple geometries such as spheres and cylinders and Monte Carlo (MC) simulations elsewhere. Our hybrid method remains valid for any acquisition parameters and provides identical levels of accuracy with a computational time that is 90% shorter than that required by MC simulations for commonly-encountered microstructural configurations. We apply our novel simulation technique to estimate the radius of axons under various noise levels with different acquisition protocols commonly used in the literature. The results of our comparison suggest that protocols favoring a large number of gradient intensities such as a Cube and Sphere (CUSP) imaging provide more accurate radius estimation than conventional single-shell HARDI acquisitions for an identical acquisition time.

  3. Industrial Compositional Streamline Simulation for Efficient and Accurate Prediction of Gas Injection and WAG Processes

    SciTech Connect

    Margot Gerritsen

    2008-10-31

    Gas-injection processes are widely and increasingly used for enhanced oil recovery (EOR). In the United States, for example, EOR production by gas injection accounts for approximately 45% of total EOR production and has tripled since 1986. The understanding of the multiphase, multicomponent flow taking place in any displacement process is essential for successful design of gas-injection projects. Due to complex reservoir geometry, reservoir fluid properties and phase behavior, the design of accurate and efficient numerical simulations for the multiphase, multicomponent flow governing these processes is nontrivial. In this work, we developed, implemented and tested a streamline based solver for gas injection processes that is computationally very attractive: as compared to traditional Eulerian solvers in use by industry it computes solutions with a computational speed orders of magnitude higher and a comparable accuracy provided that cross-flow effects do not dominate. We contributed to the development of compositional streamline solvers in three significant ways: improvement of the overall framework allowing improved streamline coverage and partial streamline tracing, amongst others; parallelization of the streamline code, which significantly improves wall clock time; and development of new compositional solvers that can be implemented along streamlines as well as in existing Eulerian codes used by industry. We designed several novel ideas in the streamline framework. First, we developed an adaptive streamline coverage algorithm. Adding streamlines locally can reduce computational costs by concentrating computational efforts where needed, and reduce mapping errors. Adapting streamline coverage effectively controls mass balance errors that mostly result from the mapping from streamlines to pressure grid. We also introduced the concept of partial streamlines: streamlines that do not necessarily start and/or end at wells. This allows more efficient coverage and avoids

  4. Turmoil: A Simulation Game Dealing With International Oil Trade

    ERIC Educational Resources Information Center

    Kelly, Robert

    1976-01-01

    This simulation game is intended to help secondary students understand the complexities of the international oil trade. Students represent nations involved in trading oil and other commodities. The game takes about five classroom periods to teach. The article includes all essential materials. (Author/RM)

  5. Parallel kinetic Monte Carlo simulation framework incorporating accurate models of adsorbate lateral interactions

    NASA Astrophysics Data System (ADS)

    Nielsen, Jens; d'Avezac, Mayeul; Hetherington, James; Stamatakis, Michail

    2013-12-01

    Ab initio kinetic Monte Carlo (KMC) simulations have been successfully applied for over two decades to elucidate the underlying physico-chemical phenomena on the surfaces of heterogeneous catalysts. These simulations necessitate detailed knowledge of the kinetics of elementary reactions constituting the reaction mechanism, and the energetics of the species participating in the chemistry. The information about the energetics is encoded in the formation energies of gas and surface-bound species, and the lateral interactions between adsorbates on the catalytic surface, which can be modeled at different levels of detail. The majority of previous works accounted for only pairwise-additive first nearest-neighbor interactions. More recently, cluster-expansion Hamiltonians incorporating long-range interactions and many-body terms have been used for detailed estimations of catalytic rate [C. Wu, D. J. Schmidt, C. Wolverton, and W. F. Schneider, J. Catal. 286, 88 (2012)]. In view of the increasing interest in accurate predictions of catalytic performance, there is a need for general-purpose KMC approaches incorporating detailed cluster expansion models for the adlayer energetics. We have addressed this need by building on the previously introduced graph-theoretical KMC framework, and we have developed Zacros, a FORTRAN2003 KMC package for simulating catalytic chemistries. To tackle the high computational cost in the presence of long-range interactions we introduce parallelization with OpenMP. We further benchmark our framework by simulating a KMC analogue of the NO oxidation system established by Schneider and co-workers [J. Catal. 286, 88 (2012)]. We show that taking into account only first nearest-neighbor interactions may lead to large errors in the prediction of the catalytic rate, whereas for accurate estimates thereof, one needs to include long-range terms in the cluster expansion.

  6. Reducing US Oil Dependence Using Simulation

    NASA Technical Reports Server (NTRS)

    Ayoub, Fadi; Arnaout, Georges M.

    2011-01-01

    People across the world are addicted to oil; as a result, the instability of oil prices and the shortage of oil reserves have influenced human behaviors and global businesses. Today, the United States makes up only 5% of the global population but consumes 25% of the. world total energy. Most of this energy is generated from fossil fuels in the form of electricity. The contribution of this paper is to examine the possibilities of replacing fossil fuel with renewable energies to generate electricity as well as to examine other methods to reduce oil and gas consumption. We propose a system dynamics model in an attempt to predict the future US dependence on fossil fuels by using renewable energy resources such as, nuclear, wind, solar, and hydro powers. Based on the findings of our model, the study expects to provide insights towards promising solutions of the oil dependency problem.

  7. Recommendations for accurate numerical blood flow simulations of stented intracranial aneurysms.

    PubMed

    Janiga, Gábor; Berg, Philipp; Beuing, Oliver; Neugebauer, Mathias; Gasteiger, Rocco; Preim, Bernhard; Rose, Georg; Skalej, Martin; Thévenin, Dominique

    2013-06-01

    The number of scientific publications dealing with stented intracranial aneurysms is rapidly increasing. Powerful computational facilities are now available; an accurate computational modeling of hemodynamics in patient-specific configurations is, however, still being sought. Furthermore, there is still no general agreement on the quantities that should be computed and on the most adequate analysis for intervention support. In this article, the accurate representation of patient geometry is first discussed, involving successive improvements. Concerning the second step, the mesh required for the numerical simulation is especially challenging when deploying a stent with very fine wire structures. Third, the description of the fluid properties is a major challenge. Finally, a founded quantitative analysis of the simulation results is obviously needed to support interventional decisions. In the present work, an attempt has been made to review the most important steps for a high-quality computational fluid dynamics computation of virtually stented intracranial aneurysms. In consequence, this leads to concrete recommendations, whereby the obtained results are not discussed for their medical relevance but for the evaluation of their quality. This investigation might hopefully be helpful for further studies considering stent deployment in patient-specific geometries, in particular regarding the generation of the most appropriate computational model. PMID:23729530

  8. Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, William L.; Glass, Christopher E.; Streett, Craig L.; Schuster, David M.

    2015-01-01

    A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS.

  9. Simulation of residual oil displacement in a sinusoidal channel with the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Otomo, Hiroshi; Fan, Hongli; Hazlett, Randy; Li, Yong; Staroselsky, Ilya; Zhang, Raoyang; Chen, Hudong

    2015-10-01

    We simulate oil slug displacement in a sinusoidal channel in order to validate computational models and algorithms for multi-component flow. This case fits in the gap between fully realistic cases characterized by complicated geometry and academic cases with simplistic geometry. Our computational model is based on the lattice Boltzmann method and allows for variation of physical parameters such as wettability and viscosity. The effect of variation of model parameters is analyzed, in particular via comparison with analytical solutions. We discuss the requirements for accurate solution of the oil slug displacement problem.

  10. Hydration free energies of cyanide and hydroxide ions from molecular dynamics simulations with accurate force fields

    USGS Publications Warehouse

    Lee, M.W.; Meuwly, M.

    2013-01-01

    The evaluation of hydration free energies is a sensitive test to assess force fields used in atomistic simulations. We showed recently that the vibrational relaxation times, 1D- and 2D-infrared spectroscopies for CN(-) in water can be quantitatively described from molecular dynamics (MD) simulations with multipolar force fields and slightly enlarged van der Waals radii for the C- and N-atoms. To validate such an approach, the present work investigates the solvation free energy of cyanide in water using MD simulations with accurate multipolar electrostatics. It is found that larger van der Waals radii are indeed necessary to obtain results close to the experimental values when a multipolar force field is used. For CN(-), the van der Waals ranges refined in our previous work yield hydration free energy between -72.0 and -77.2 kcal mol(-1), which is in excellent agreement with the experimental data. In addition to the cyanide ion, we also study the hydroxide ion to show that the method used here is readily applicable to similar systems. Hydration free energies are found to sensitively depend on the intermolecular interactions, while bonded interactions are less important, as expected. We also investigate in the present work the possibility of applying the multipolar force field in scoring trajectories generated using computationally inexpensive methods, which should be useful in broader parametrization studies with reduced computational resources, as scoring is much faster than the generation of the trajectories.

  11. Accurate load prediction by BEM with airfoil data from 3D RANS simulations

    NASA Astrophysics Data System (ADS)

    Schneider, Marc S.; Nitzsche, Jens; Hennings, Holger

    2016-09-01

    In this paper, two methods for the extraction of airfoil coefficients from 3D CFD simulations of a wind turbine rotor are investigated, and these coefficients are used to improve the load prediction of a BEM code. The coefficients are extracted from a number of steady RANS simulations, using either averaging of velocities in annular sections, or an inverse BEM approach for determination of the induction factors in the rotor plane. It is shown that these 3D rotor polars are able to capture the rotational augmentation at the inner part of the blade as well as the load reduction by 3D effects close to the blade tip. They are used as input to a simple BEM code and the results of this BEM with 3D rotor polars are compared to the predictions of BEM with 2D airfoil coefficients plus common empirical corrections for stall delay and tip loss. While BEM with 2D airfoil coefficients produces a very different radial distribution of loads than the RANS simulation, the BEM with 3D rotor polars manages to reproduce the loads from RANS very accurately for a variety of load cases, as long as the blade pitch angle is not too different from the cases from which the polars were extracted.

  12. A hybrid Boundary Element Unstructured Transmission-line (BEUT) method for accurate 2D electromagnetic simulation

    NASA Astrophysics Data System (ADS)

    Simmons, Daniel; Cools, Kristof; Sewell, Phillip

    2016-11-01

    Time domain electromagnetic simulation tools have the ability to model transient, wide-band applications, and non-linear problems. The Boundary Element Method (BEM) and the Transmission Line Modeling (TLM) method are both well established numerical techniques for simulating time-varying electromagnetic fields. The former surface based method can accurately describe outwardly radiating fields from piecewise uniform objects and efficiently deals with large domains filled with homogeneous media. The latter volume based method can describe inhomogeneous and non-linear media and has been proven to be unconditionally stable. Furthermore, the Unstructured TLM (UTLM) enables modelling of geometrically complex objects by using triangular meshes which removes staircasing and unnecessary extensions of the simulation domain. The hybridization of BEM and UTLM which is described in this paper is named the Boundary Element Unstructured Transmission-line (BEUT) method. It incorporates the advantages of both methods. The theory and derivation of the 2D BEUT method is described in this paper, along with any relevant implementation details. The method is corroborated by studying its correctness and efficiency compared to the traditional UTLM method when applied to complex problems such as the transmission through a system of Luneburg lenses and the modelling of antenna radomes for use in wireless communications.

  13. Numerical Methodology for Coupled Time-Accurate Simulations of Primary and Secondary Flowpaths in Gas Turbines

    NASA Technical Reports Server (NTRS)

    Przekwas, A. J.; Athavale, M. M.; Hendricks, R. C.; Steinetz, B. M.

    2006-01-01

    Detailed information of the flow-fields in the secondary flowpaths and their interaction with the primary flows in gas turbine engines is necessary for successful designs with optimized secondary flow streams. Present work is focused on the development of a simulation methodology for coupled time-accurate solutions of the two flowpaths. The secondary flowstream is treated using SCISEAL, an unstructured adaptive Cartesian grid code developed for secondary flows and seals, while the mainpath flow is solved using TURBO, a density based code with capability of resolving rotor-stator interaction in multi-stage machines. An interface is being tested that links the two codes at the rim seal to allow data exchange between the two codes for parallel, coupled execution. A description of the coupling methodology and the current status of the interface development is presented. Representative steady-state solutions of the secondary flow in the UTRC HP Rig disc cavity are also presented.

  14. Object-Oriented NeuroSys: Parallel Programs for Simulating Large Networks of Biologically Accurate Neurons

    SciTech Connect

    Pacheco, P; Miller, P; Kim, J; Leese, T; Zabiyaka, Y

    2003-05-07

    Object-oriented NeuroSys (ooNeuroSys) is a collection of programs for simulating very large networks of biologically accurate neurons on distributed memory parallel computers. It includes two principle programs: ooNeuroSys, a parallel program for solving the large systems of ordinary differential equations arising from the interconnected neurons, and Neurondiz, a parallel program for visualizing the results of ooNeuroSys. Both programs are designed to be run on clusters and use the MPI library to obtain parallelism. ooNeuroSys also includes an easy-to-use Python interface. This interface allows neuroscientists to quickly develop and test complex neuron models. Both ooNeuroSys and Neurondiz have a design that allows for both high performance and relative ease of maintenance.

  15. Time-Accurate Simulations and Acoustic Analysis of Slat Free-Shear Layer

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Singer, Bart A.; Berkman, Mert E.

    2001-01-01

    A detailed computational aeroacoustic analysis of a high-lift flow field is performed. Time-accurate Reynolds Averaged Navier-Stokes (RANS) computations simulate the free shear layer that originates from the slat cusp. Both unforced and forced cases are studied. Preliminary results show that the shear layer is a good amplifier of disturbances in the low to mid-frequency range. The Ffowcs-Williams and Hawkings equation is solved to determine the acoustic field using the unsteady flow data from the RANS calculations. The noise radiated from the excited shear layer has a spectral shape qualitatively similar to that obtained from measurements in a corresponding experimental study of the high-lift system.

  16. Cartesian Off-Body Grid Adaption for Viscous Time- Accurate Flow Simulation

    NASA Technical Reports Server (NTRS)

    Buning, Pieter G.; Pulliam, Thomas H.

    2011-01-01

    An improved solution adaption capability has been implemented in the OVERFLOW overset grid CFD code. Building on the Cartesian off-body approach inherent in OVERFLOW and the original adaptive refinement method developed by Meakin, the new scheme provides for automated creation of multiple levels of finer Cartesian grids. Refinement can be based on the undivided second-difference of the flow solution variables, or on a specific flow quantity such as vorticity. Coupled with load-balancing and an inmemory solution interpolation procedure, the adaption process provides very good performance for time-accurate simulations on parallel compute platforms. A method of using refined, thin body-fitted grids combined with adaption in the off-body grids is presented, which maximizes the part of the domain subject to adaption. Two- and three-dimensional examples are used to illustrate the effectiveness and performance of the adaption scheme.

  17. Time-Accurate Computational Fluid Dynamics Simulation of a Pair of Moving Solid Rocket Boosters

    NASA Technical Reports Server (NTRS)

    Strutzenberg, Louise L.; Williams, Brandon R.

    2011-01-01

    Since the Columbia accident, the threat to the Shuttle launch vehicle from debris during the liftoff timeframe has been assessed by the Liftoff Debris Team at NASA/MSFC. In addition to engineering methods of analysis, CFD-generated flow fields during the liftoff timeframe have been used in conjunction with 3-DOF debris transport methods to predict the motion of liftoff debris. Early models made use of a quasi-steady flow field approximation with the vehicle positioned at a fixed location relative to the ground; however, a moving overset mesh capability has recently been developed for the Loci/CHEM CFD software which enables higher-fidelity simulation of the Shuttle transient plume startup and liftoff environment. The present work details the simulation of the launch pad and mobile launch platform (MLP) with truncated solid rocket boosters (SRBs) moving in a prescribed liftoff trajectory derived from Shuttle flight measurements. Using Loci/CHEM, time-accurate RANS and hybrid RANS/LES simulations were performed for the timeframe T0+0 to T0+3.5 seconds, which consists of SRB startup to a vehicle altitude of approximately 90 feet above the MLP. Analysis of the transient flowfield focuses on the evolution of the SRB plumes in the MLP plume holes and the flame trench, impingement on the flame deflector, and especially impingment on the MLP deck resulting in upward flow which is a transport mechanism for debris. The results show excellent qualitative agreement with the visual record from past Shuttle flights, and comparisons to pressure measurements in the flame trench and on the MLP provide confidence in these simulation capabilities.

  18. Oil Droplet Size Distribution and Optical Properties During Wave Tank Simulated Oil Spills

    NASA Astrophysics Data System (ADS)

    Conmy, R. N.; Venosa, A.; Courtenay, S.; King, T.; Robinson, B.; Ryan, S.

    2013-12-01

    Fate and transport of spilled petroleum oils in aquatic environments is highly dependent upon oil droplet behavior which is a function of chemical composition, dispersibility (natural and chemically-enhanced) and droplet size distribution (DSD) of the oil. DSD is influenced by mixing energy, temperature, salinity, pressure, presence of dissolved and particulate materials, flow rate of release, and application of dispersants. To better understand DSD and droplet behavior under varying physical conditions, flask-scale experiments are often insufficient. Rather, wave tank simulations allow for scaling to field conditions. Presented here are experiment results from the Bedford Institute of Oceanography wave tank facility, where chemically-dispersed (Corexit 9500; DOR = 1:20) Louisiana Sweet crude, IFO-120 and ANS crude oil were exposed to mixing energies to achieve dispersant effectiveness observed in the field. Oil plumes were simulated, both surface and subsea releases with varying water temperature and flow rate. Fluorometers (Chelsea Technologies Group AQUATracka, Turner Designs Cyclops, WET Labs Inc ECO) and particle size analyzers (Sequoia LISST) were used to track the dispersed plumes in the tank and characterize oil droplets. Sensors were validated with known oil volumes (down to 300 ppb) and measured Total Petroleum Hydrocarbons (TPH) and Benzene-Toluene-Ethylbenzene-Xylene (BTEX) values. This work has large implications for tracking surface and deep sea oil plumes with fluorescence and particle size analyzers, improved weathering and biodegradation estimates, and understanding the fate and transport of spill oil.

  19. An accurate and efficient 3-D micromagnetic simulation of metal evaporated tape

    NASA Astrophysics Data System (ADS)

    Jones, M.; Miles, J. J.

    1997-07-01

    Metal evaporated tape (MET) has a complex column-like structure in which magnetic domains are arranged randomly. In order to accurately simulate the behaviour of MET it is important to capture these aspects of the material in a high-resolution 3-D micromagnetic model. The scale of this problem prohibits the use of traditional scalar computers and leads us to develop algorithms for a vector processor architecture. We demonstrate that despite the materials highly non-uniform structure, it is possible to develop fast vector algorithms for the computation of the magnetostatic interaction field. We do this by splitting the field calculation into near and far components. The near field component is calculated exactly using an efficient vector algorithm, whereas the far field is calculated approximately using a novel fast Fourier transform (FFT) technique. Results are presented which demonstrate that, in practice, the algorithms require sub-O( N log( N)) computation time. In addition results of highly realistic simulation of hysteresis in MET are presented.

  20. How to obtain accurate resist simulations in very low-k1 era?

    NASA Astrophysics Data System (ADS)

    Chiou, Tsann-Bim; Park, Chan-Ha; Choi, Jae-Seung; Min, Young-Hong; Hansen, Steve; Tseng, Shih-En; Chen, Alek C.; Yim, Donggyu

    2006-03-01

    A procedure for calibrating a resist model iteratively adjusts appropriate parameters until the simulations of the model match the experimental data. The tunable parameters may include the shape of the illuminator, the geometry and transmittance/phase of the mask, light source and scanner-related parameters that affect imaging quality, resist process control and most importantly the physical/chemical factors in the resist model. The resist model can be accurately calibrated by measuring critical dimensions (CD) of a focus-exposure matrix (FEM) and the technique has been demonstrated to be very successful in predicting lithographic performance. However, resist model calibration is more challenging in the low k1 (<0.3) regime because numerous uncertainties, such as mask and resist CD metrology errors, are becoming too large to be ignored. This study demonstrates a resist model calibration procedure for a 0.29 k1 process using a 6% halftone mask containing 2D brickwall patterns. The influence of different scanning electron microscopes (SEM) and their wafer metrology signal analysis algorithms on the accuracy of the resist model is evaluated. As an example of the metrology issue of the resist pattern, the treatment of a sidewall angle is demonstrated for the resist line ends where the contrast is relatively low. Additionally, the mask optical proximity correction (OPC) and corner rounding are considered in the calibration procedure that is based on captured SEM images. Accordingly, the average root-mean-square (RMS) error, which is the difference between simulated and experimental CDs, can be improved by considering the metrological issues. Moreover, a weighting method and a measured CD tolerance are proposed to handle the different CD variations of the various edge points of the wafer resist pattern. After the weighting method is implemented and the CD selection criteria applied, the RMS error can be further suppressed. Therefore, the resist CD and process window can

  1. ILT based defect simulation of inspection images accurately predicts mask defect printability on wafer

    NASA Astrophysics Data System (ADS)

    Deep, Prakash; Paninjath, Sankaranarayanan; Pereira, Mark; Buck, Peter

    2016-05-01

    At advanced technology nodes mask complexity has been increased because of large-scale use of resolution enhancement technologies (RET) which includes Optical Proximity Correction (OPC), Inverse Lithography Technology (ILT) and Source Mask Optimization (SMO). The number of defects detected during inspection of such mask increased drastically and differentiation of critical and non-critical defects are more challenging, complex and time consuming. Because of significant defectivity of EUVL masks and non-availability of actinic inspection, it is important and also challenging to predict the criticality of defects for printability on wafer. This is one of the significant barriers for the adoption of EUVL for semiconductor manufacturing. Techniques to decide criticality of defects from images captured using non actinic inspection images is desired till actinic inspection is not available. High resolution inspection of photomask images detects many defects which are used for process and mask qualification. Repairing all defects is not practical and probably not required, however it's imperative to know which defects are severe enough to impact wafer before repair. Additionally, wafer printability check is always desired after repairing a defect. AIMSTM review is the industry standard for this, however doing AIMSTM review for all defects is expensive and very time consuming. Fast, accurate and an economical mechanism is desired which can predict defect printability on wafer accurately and quickly from images captured using high resolution inspection machine. Predicting defect printability from such images is challenging due to the fact that the high resolution images do not correlate with actual mask contours. The challenge is increased due to use of different optical condition during inspection other than actual scanner condition, and defects found in such images do not have correlation with actual impact on wafer. Our automated defect simulation tool predicts

  2. Simulation of Gravity Feed Oil for Areoplane Fuel Transfer System

    NASA Astrophysics Data System (ADS)

    Lv, Y. G.; Liu, Z. X.; Huang, S. Q.; Xu, T.

    Generally, it has two different ways for fuel transfer for areoplane, the simplest one is by gravity, and another is by pumps. But the simplest one mighte change to the vital method in some situation, such as electrical and mechanical accident. So the study of gravity feed oil is aslo important. Past calculations assumed that, under gravity feed, only one fuel tank in aircraft supplies the fuel needed for preventing extremely serious accident to happen. Actually, gravity feed oil is a transient process, all fuel tanks compete for supplying oil and there must have several fuel tanks offering oil simultaneously. The key problems to calculate gravity feed oil are the sumulation of the multiple-branch and transient process. Firstly, we presented mathematical models for oil flow through pipes, non-working pupms and check valves, ect. Secondly, On the basis of flow network theory and time difference method, we established a new calculation method for gravity feed oil of aeroplane fuel system. This model can solve the multiple-branch and transient process simulation of gravity feed oil. Our method takes into consideration all fuel tanks and therefore, we believe, our method is intrinsically superior to traditional methods and is closer to understanding the real seriousness of the oil supply situation. Finally, we give a numerical example using the new method for a certain type of aircraft under gravity feed. achieved the variations of oil level and flow mass per second of each oil tanks which showed in Figures below. These variations show preliminarily that our proposed method of calculations is satisfactory.

  3. CHARACTERISTICS OF SPILLED OILS, FUELS, AND PETROLEUM PRODUCTS: 3A. SIMULATION OF OIL SPILLS AND DISPERSANTS UNDER CONDITIONS OF UNCERTAINTY

    EPA Science Inventory

    At the request of the US EPA Oil Program Center, ERD is developing an oil spill model that focuses on fate and transport of oil components under various response scenarios. This model includes various simulation options, including the use of chemical dispersing agents on oil sli...

  4. An accurate conservative level set/ghost fluid method for simulating turbulent atomization

    SciTech Connect

    Desjardins, Olivier Moureau, Vincent; Pitsch, Heinz

    2008-09-10

    This paper presents a novel methodology for simulating incompressible two-phase flows by combining an improved version of the conservative level set technique introduced in [E. Olsson, G. Kreiss, A conservative level set method for two phase flow, J. Comput. Phys. 210 (2005) 225-246] with a ghost fluid approach. By employing a hyperbolic tangent level set function that is transported and re-initialized using fully conservative numerical schemes, mass conservation issues that are known to affect level set methods are greatly reduced. In order to improve the accuracy of the conservative level set method, high order numerical schemes are used. The overall robustness of the numerical approach is increased by computing the interface normals from a signed distance function reconstructed from the hyperbolic tangent level set by a fast marching method. The convergence of the curvature calculation is ensured by using a least squares reconstruction. The ghost fluid technique provides a way of handling the interfacial forces and large density jumps associated with two-phase flows with good accuracy, while avoiding artificial spreading of the interface. Since the proposed approach relies on partial differential equations, its implementation is straightforward in all coordinate systems, and it benefits from high parallel efficiency. The robustness and efficiency of the approach is further improved by using implicit schemes for the interface transport and re-initialization equations, as well as for the momentum solver. The performance of the method is assessed through both classical level set transport tests and simple two-phase flow examples including topology changes. It is then applied to simulate turbulent atomization of a liquid Diesel jet at Re=3000. The conservation errors associated with the accurate conservative level set technique are shown to remain small even for this complex case.

  5. A Three-Dimensional Parallel Time-Accurate Turbopump Simulation Procedure Using Overset Grid System

    NASA Technical Reports Server (NTRS)

    Kiris, Cetin; Chan, William; Kwak, Dochan

    2002-01-01

    The objective of the current effort is to provide a computational framework for design and analysis of the entire fuel supply system of a liquid rocket engine, including high-fidelity unsteady turbopump flow analysis. This capability is needed to support the design of pump sub-systems for advanced space transportation vehicles that are likely to involve liquid propulsion systems. To date, computational tools for design/analysis of turbopump flows are based on relatively lower fidelity methods. An unsteady, three-dimensional viscous flow analysis tool involving stationary and rotational components for the entire turbopump assembly has not been available for real-world engineering applications. The present effort provides developers with information such as transient flow phenomena at start up, and nonuniform inflows, and will eventually impact on system vibration and structures. In the proposed paper, the progress toward the capability of complete simulation of the turbo-pump for a liquid rocket engine is reported. The Space Shuttle Main Engine (SSME) turbo-pump is used as a test case for evaluation of the hybrid MPI/Open-MP and MLP versions of the INS3D code. CAD to solution auto-scripting capability is being developed for turbopump applications. The relative motion of the grid systems for the rotor-stator interaction was obtained using overset grid techniques. Unsteady computations for the SSME turbo-pump, which contains 114 zones with 34.5 million grid points, are carried out on Origin 3000 systems at NASA Ames Research Center. Results from these time-accurate simulations with moving boundary capability are presented along with the performance of parallel versions of the code.

  6. A Three Dimensional Parallel Time Accurate Turbopump Simulation Procedure Using Overset Grid Systems

    NASA Technical Reports Server (NTRS)

    Kiris, Cetin; Chan, William; Kwak, Dochan

    2001-01-01

    The objective of the current effort is to provide a computational framework for design and analysis of the entire fuel supply system of a liquid rocket engine, including high-fidelity unsteady turbopump flow analysis. This capability is needed to support the design of pump sub-systems for advanced space transportation vehicles that are likely to involve liquid propulsion systems. To date, computational tools for design/analysis of turbopump flows are based on relatively lower fidelity methods. An unsteady, three-dimensional viscous flow analysis tool involving stationary and rotational components for the entire turbopump assembly has not been available for real-world engineering applications. The present effort provides developers with information such as transient flow phenomena at start up, and non-uniform inflows, and will eventually impact on system vibration and structures. In the proposed paper, the progress toward the capability of complete simulation of the turbo-pump for a liquid rocket engine is reported. The Space Shuttle Main Engine (SSME) turbo-pump is used as a test case for evaluation of the hybrid MPI/Open-MP and MLP versions of the INS3D code. CAD to solution auto-scripting capability is being developed for turbopump applications. The relative motion of the grid systems for the rotor-stator interaction was obtained using overset grid techniques. Unsteady computations for the SSME turbo-pump, which contains 114 zones with 34.5 million grid points, are carried out on Origin 3000 systems at NASA Ames Research Center. Results from these time-accurate simulations with moving boundary capability will be presented along with the performance of parallel versions of the code.

  7. Accurate and computationally efficient mixing models for the simulation of turbulent mixing with PDF methods

    NASA Astrophysics Data System (ADS)

    Meyer, Daniel W.; Jenny, Patrick

    2013-08-01

    Different simulation methods are applicable to study turbulent mixing. When applying probability density function (PDF) methods, turbulent transport, and chemical reactions appear in closed form, which is not the case in second moment closure methods (RANS). Moreover, PDF methods provide the entire joint velocity-scalar PDF instead of a limited set of moments. In PDF methods, however, a mixing model is required to account for molecular diffusion. In joint velocity-scalar PDF methods, mixing models should also account for the joint velocity-scalar statistics, which is often under appreciated in applications. The interaction by exchange with the conditional mean (IECM) model accounts for these joint statistics, but requires velocity-conditional scalar means that are expensive to compute in spatially three dimensional settings. In this work, two alternative mixing models are presented that provide more accurate PDF predictions at reduced computational cost compared to the IECM model, since no conditional moments have to be computed. All models are tested for different mixing benchmark cases and their computational efficiencies are inspected thoroughly. The benchmark cases involve statistically homogeneous and inhomogeneous settings dealing with three streams that are characterized by two passive scalars. The inhomogeneous case clearly illustrates the importance of accounting for joint velocity-scalar statistics in the mixing model. Failure to do so leads to significant errors in the resulting scalar means, variances and other statistics.

  8. Molecular Simulation of Carbon Dioxide Capture by Montmorillonite Using an Accurate and Flexible Force Field

    SciTech Connect

    Romanov, V N; Cygan, R T; Myshakin, E M

    2012-06-21

    Naturally occurring clay minerals provide a distinctive material for carbon capture and carbon dioxide sequestration. Swelling clay minerals, such as the smectite variety, possess an aluminosilicate structure that is controlled by low-charge layers that readily expand to accommodate water molecules and, potentially, CO2. Recent experimental studies have demonstrated the efficacy of intercalating CO2 in the interlayer of layered clays, but little is known about the molecular mechanisms of the process and the extent of carbon capture as a function of clay charge and structure. A series of molecular dynamics simulations and vibrational analyses have been completed to assess the molecular interactions associated with incorporation of CO2 and H2O in the interlayer of montmorillonite clay and to help validate the models with experimental observation. An accurate and fully flexible set of interatomic potentials for CO2 is developed and combined with Clayff potentials to help evaluate the intercalation mechanism and examine the effect of molecular flexibility onthe diffusion rate of CO2 in water.

  9. Parallel Higher-order Finite Element Method for Accurate Field Computations in Wakefield and PIC Simulations

    SciTech Connect

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Ko, K.; /SLAC

    2009-06-19

    Over the past years, SLAC's Advanced Computations Department (ACD), under SciDAC sponsorship, has developed a suite of 3D (2D) parallel higher-order finite element (FE) codes, T3P (T2P) and Pic3P (Pic2P), aimed at accurate, large-scale simulation of wakefields and particle-field interactions in radio-frequency (RF) cavities of complex shape. The codes are built on the FE infrastructure that supports SLAC's frequency domain codes, Omega3P and S3P, to utilize conformal tetrahedral (triangular)meshes, higher-order basis functions and quadratic geometry approximation. For time integration, they adopt an unconditionally stable implicit scheme. Pic3P (Pic2P) extends T3P (T2P) to treat charged-particle dynamics self-consistently using the PIC (particle-in-cell) approach, the first such implementation on a conformal, unstructured grid using Whitney basis functions. Examples from applications to the International Linear Collider (ILC), Positron Electron Project-II (PEP-II), Linac Coherent Light Source (LCLS) and other accelerators will be presented to compare the accuracy and computational efficiency of these codes versus their counterparts using structured grids.

  10. Numerical simulation of oil pool boundary evolution

    NASA Astrophysics Data System (ADS)

    Khudobina, Yulia; Bubenchikov, Aleksey; Bubenchikov, Mikhail; Matvienko, Oleg; Libin, Eduard

    2016-01-01

    The study of spatial distribution of hydrocarbon resources and forecasting their geographical location is of great importance for the most complete recovery of hydrocarbons from deposits. The present study gives new mathematical results in the theory of stratified fluid flow in a porous medium. This paper analyzes the evolution of oil pool boundary basing on vortex numerical model for movement of the boundary separating fluids of different densities. It presents the investigation of how the location of light fluid regarding the heavier fluid influences on the changes in the boundary between two media in case of various shifting of the well.

  11. A mechanistic approach for accurate simulation of village scale malaria transmission

    PubMed Central

    Bomblies, Arne; Duchemin, Jean-Bernard; Eltahir, Elfatih AB

    2009-01-01

    Background Malaria transmission models commonly incorporate spatial environmental and climate variability for making regional predictions of disease risk. However, a mismatch of these models' typical spatial resolutions and the characteristic scale of malaria vector population dynamics may confound disease risk predictions in areas of high spatial hydrological variability such as the Sahel region of Africa. Methods Field observations spanning two years from two Niger villages are compared. The two villages are separated by only 30 km but exhibit a ten-fold difference in anopheles mosquito density. These two villages would be covered by a single grid cell in many malaria models, yet their entomological activity differs greatly. Environmental conditions and associated entomological activity are simulated at high spatial- and temporal resolution using a mechanistic approach that couples a distributed hydrology scheme and an entomological model. Model results are compared to regular field observations of Anopheles gambiae sensu lato mosquito populations and local hydrology. The model resolves the formation and persistence of individual pools that facilitate mosquito breeding and predicts spatio-temporal mosquito population variability at high resolution using an agent-based modeling approach. Results Observations of soil moisture, pool size, and pool persistence are reproduced by the model. The resulting breeding of mosquitoes in the simulated pools yields time-integrated seasonal mosquito population dynamics that closely follow observations from captured mosquito abundance. Interannual difference in mosquito abundance is simulated, and the inter-village difference in mosquito population is reproduced for two years of observations. These modeling results emulate the known focal nature of malaria in Niger Sahel villages. Conclusion Hydrological variability must be represented at high spatial and temporal resolution to achieve accurate predictive ability of malaria risk

  12. Experiences with linear solvers for oil reservoir simulation problems

    SciTech Connect

    Joubert, W.; Janardhan, R.; Biswas, D.; Carey, G.

    1996-12-31

    This talk will focus on practical experiences with iterative linear solver algorithms used in conjunction with Amoco Production Company`s Falcon oil reservoir simulation code. The goal of this study is to determine the best linear solver algorithms for these types of problems. The results of numerical experiments will be presented.

  13. A time-accurate adaptive grid method and the numerical simulation of a shock-vortex interaction

    NASA Technical Reports Server (NTRS)

    Bockelie, Michael J.; Eiseman, Peter R.

    1990-01-01

    A time accurate, general purpose, adaptive grid method is developed that is suitable for multidimensional steady and unsteady numerical simulations. The grid point movement is performed in a manner that generates smooth grids which resolve the severe solution gradients and the sharp transitions in the solution gradients. The temporal coupling of the adaptive grid and the PDE solver is performed with a grid prediction correction method that is simple to implement and ensures the time accuracy of the grid. Time accurate solutions of the 2-D Euler equations for an unsteady shock vortex interaction demonstrate the ability of the adaptive method to accurately adapt the grid to multiple solution features.

  14. Physical and Numerical Model Studies of Cross-flow Turbines Towards Accurate Parameterization in Array Simulations

    NASA Astrophysics Data System (ADS)

    Wosnik, M.; Bachant, P.

    2014-12-01

    Cross-flow turbines, often referred to as vertical-axis turbines, show potential for success in marine hydrokinetic (MHK) and wind energy applications, ranging from small- to utility-scale installations in tidal/ocean currents and offshore wind. As turbine designs mature, the research focus is shifting from individual devices to the optimization of turbine arrays. It would be expensive and time-consuming to conduct physical model studies of large arrays at large model scales (to achieve sufficiently high Reynolds numbers), and hence numerical techniques are generally better suited to explore the array design parameter space. However, since the computing power available today is not sufficient to conduct simulations of the flow in and around large arrays of turbines with fully resolved turbine geometries (e.g., grid resolution into the viscous sublayer on turbine blades), the turbines' interaction with the energy resource (water current or wind) needs to be parameterized, or modeled. Models used today--a common model is the actuator disk concept--are not able to predict the unique wake structure generated by cross-flow turbines. This wake structure has been shown to create "constructive" interference in some cases, improving turbine performance in array configurations, in contrast with axial-flow, or horizontal axis devices. Towards a more accurate parameterization of cross-flow turbines, an extensive experimental study was carried out using a high-resolution turbine test bed with wake measurement capability in a large cross-section tow tank. The experimental results were then "interpolated" using high-fidelity Navier--Stokes simulations, to gain insight into the turbine's near-wake. The study was designed to achieve sufficiently high Reynolds numbers for the results to be Reynolds number independent with respect to turbine performance and wake statistics, such that they can be reliably extrapolated to full scale and used for model validation. The end product of

  15. Simulation of oil pollution in the Persian Gulf near Assaluyeh oil terminal.

    PubMed

    Faghihifard, M; Badri, M A

    2016-04-15

    Numerical simulation of oil slick movement with respect to tidal factors and wind effects was performed in order to counteract oil pollution in the Persian Gulf. First, a flow model was invoked with respect to water level fluctuations. The main tidal constituents were applied to the model using the initial conditions of water level variations in the Hormuz Strait near the Hangam Island. The movement of oil pollution was determined due to wind, tide and temperature effects and confirmed by applying a verified field results. Simulations were focused near an important terminal in the Persian Gulf, Assaluyeh Port. The results were led to preparing a risk-taking map in a parallel research for the Persian Gulf. PMID:26906497

  16. Simulation of oil pollution in the Persian Gulf near Assaluyeh oil terminal.

    PubMed

    Faghihifard, M; Badri, M A

    2016-04-15

    Numerical simulation of oil slick movement with respect to tidal factors and wind effects was performed in order to counteract oil pollution in the Persian Gulf. First, a flow model was invoked with respect to water level fluctuations. The main tidal constituents were applied to the model using the initial conditions of water level variations in the Hormuz Strait near the Hangam Island. The movement of oil pollution was determined due to wind, tide and temperature effects and confirmed by applying a verified field results. Simulations were focused near an important terminal in the Persian Gulf, Assaluyeh Port. The results were led to preparing a risk-taking map in a parallel research for the Persian Gulf.

  17. Molecular Simulation of the Free Energy for the Accurate Determination of Phase Transition Properties of Molecular Solids

    NASA Astrophysics Data System (ADS)

    Sellers, Michael; Lisal, Martin; Brennan, John

    2015-06-01

    Investigating the ability of a molecular model to accurately represent a real material is crucial to model development and use. When the model simulates materials in extreme conditions, one such property worth evaluating is the phase transition point. However, phase transitions are often overlooked or approximated because of difficulty or inaccuracy when simulating them. Techniques such as super-heating or super-squeezing a material to induce a phase change suffer from inherent timescale limitations leading to ``over-driving,'' and dual-phase simulations require many long-time runs to seek out what frequently results in an inexact location of phase-coexistence. We present a compilation of methods for the determination of solid-solid and solid-liquid phase transition points through the accurate calculation of the chemical potential. The methods are applied to the Smith-Bharadwaj atomistic potential's representation of cyclotrimethylene trinitramine (RDX) to accurately determine its melting point (Tm) and the alpha to gamma solid phase transition pressure. We also determine Tm for a coarse-grain model of RDX, and compare its value to experiment and atomistic counterpart. All methods are employed via the LAMMPS simulator, resulting in 60-70 simulations that total 30-50 ns. Approved for public release. Distribution is unlimited.

  18. Numerical parameter constraints for accurate PIC-DSMC simulation of breakdown from arc initiation to stable arcs

    NASA Astrophysics Data System (ADS)

    Moore, Christopher; Hopkins, Matthew; Moore, Stan; Boerner, Jeremiah; Cartwright, Keith

    2015-09-01

    Simulation of breakdown is important for understanding and designing a variety of applications such as mitigating undesirable discharge events. Such simulations need to be accurate through early time arc initiation to late time stable arc behavior. Here we examine constraints on the timestep and mesh size required for arc simulations using the particle-in-cell (PIC) method with direct simulation Monte Carlo (DMSC) collisions. Accurate simulation of electron avalanche across a fixed voltage drop and constant neutral density (reduced field of 1000 Td) was found to require a timestep ~ 1/100 of the mean time between collisions and a mesh size ~ 1/25 the mean free path. These constraints are much smaller than the typical PIC-DSMC requirements for timestep and mesh size. Both constraints are related to the fact that charged particles are accelerated by the external field. Thus gradients in the electron energy distribution function can exist at scales smaller than the mean free path and these must be resolved by the mesh size for accurate collision rates. Additionally, the timestep must be small enough that the particle energy change due to the fields be small in order to capture gradients in the cross sections versus energy. 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. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  19. Thermal numerical simulator for laboratory evaluation of steamflood oil recovery

    SciTech Connect

    Sarathi, P.

    1991-04-01

    A thermal numerical simulator running on an IBM AT compatible personal computer is described. The simulator was designed to assist laboratory design and evaluation of steamflood oil recovery. An overview of the historical evolution of numerical thermal simulation, NIPER's approach to solving these problems with a desk top computer, the derivation of equations and a description of approaches used to solve these equations, and verification of the simulator using published data sets and sensitivity analysis are presented. The developed model is a three-phase, two-dimensional multicomponent simulator capable of being run in one or two dimensions. Mass transfer among the phases and components is dictated by pressure- and temperature-dependent vapor-liquid equilibria. Gravity and capillary pressure phenomena were included. Energy is transferred by conduction, convection, vaporization and condensation. The model employs a block centered grid system with a five-point discretization scheme. Both areal and vertical cross-sectional simulations are possible. A sequential solution technique is employed to solve the finite difference equations. The study clearly indicated the importance of heat loss, injected steam quality, and injection rate to the process. Dependence of overall recovery on oil volatility and viscosity is emphasized. The process is very sensitive to relative permeability values. Time-step sensitivity runs indicted that the current version is time-step sensitive and exhibits conditional stability. 75 refs., 19 figs., 19 tabs.

  20. Navier-Stokes simulations of blade-vortex interaction using high-order accurate upwind schemes

    NASA Technical Reports Server (NTRS)

    Rai, Man Mohan

    1987-01-01

    Conventional, spatially second-order-accurate, finite-difference schemes are much too dissipative for calculations involving vortices that travel large distances (relative to some measure of the size of the vortex). This study presents a fifth-order-accurate upwind-biased scheme that preserves vortex structure for much longer times than existing second-order-accurate central and upwind difference schemes. Vortex calculations demonstrating this aspect of the fifth-order scheme are also presented. The method is then applied to the blade-vortex interaction problem. Results for strong interactions wherein the vortex impinges directly on the airfoil or a shock associated with the airfoil are presented. None of these calculations required any modeling of the shape, size, and trajectory of the interacting vortex.

  1. Accurate simulation of the electron cloud in the Fermilab Main Injector with VORPAL

    SciTech Connect

    Lebrun, Paul L.G.; Spentzouris, Panagiotis; Cary, John R.; Stoltz, Peter; Veitzer, Seth A.; /Tech-X, Boulder

    2010-05-01

    Precision simulations of the electron cloud at the Fermilab Main Injector have been studied using the plasma simulation code VORPAL. Fully 3D and self consistent solutions that includes E.M. field maps generated by the cloud and the proton bunches have been obtained, as well detailed distributions of the electron's 6D phase space. We plan to include such maps in the ongoing simulation of the space charge effects in the Main Injector. Simulations of the response of beam position monitors, retarding field analyzers and microwave transmission experiments are ongoing.

  2. Submersible optical sensors exposed to chemically dispersed crude oil: wave tank simulations for improved oil spill monitoring.

    PubMed

    Conmy, Robyn N; Coble, Paula G; Farr, James; Wood, A Michelle; Lee, Kenneth; Pegau, W Scott; Walsh, Ian D; Koch, Corey R; Abercrombie, Mary I; Miles, M Scott; Lewis, Marlon R; Ryan, Scott A; Robinson, Brian J; King, Thomas L; Kelble, Christopher R; Lacoste, Jordanna

    2014-01-01

    In situ fluorometers were deployed during the Deepwater Horizon (DWH) Gulf of Mexico oil spill to track the subsea oil plume. Uncertainties regarding instrument specifications and capabilities necessitated performance testing of sensors exposed to simulated, dispersed oil plumes. Dynamic ranges of the Chelsea Technologies Group AQUAtracka, Turner Designs Cyclops, Satlantic SUNA and WET Labs, Inc. ECO, exposed to fresh and artificially weathered crude oil, were determined. Sensors were standardized against known oil volumes and total petroleum hydrocarbons and benzene-toluene-ethylbenzene-xylene measurements-both collected during spills, providing oil estimates during wave tank dilution experiments. All sensors estimated oil concentrations down to 300 ppb oil, refuting previous reports. Sensor performance results assist interpretation of DWH oil spill data and formulating future protocols.

  3. Submersible optical sensors exposed to chemically dispersed crude oil: wave tank simulations for improved oil spill monitoring.

    PubMed

    Conmy, Robyn N; Coble, Paula G; Farr, James; Wood, A Michelle; Lee, Kenneth; Pegau, W Scott; Walsh, Ian D; Koch, Corey R; Abercrombie, Mary I; Miles, M Scott; Lewis, Marlon R; Ryan, Scott A; Robinson, Brian J; King, Thomas L; Kelble, Christopher R; Lacoste, Jordanna

    2014-01-01

    In situ fluorometers were deployed during the Deepwater Horizon (DWH) Gulf of Mexico oil spill to track the subsea oil plume. Uncertainties regarding instrument specifications and capabilities necessitated performance testing of sensors exposed to simulated, dispersed oil plumes. Dynamic ranges of the Chelsea Technologies Group AQUAtracka, Turner Designs Cyclops, Satlantic SUNA and WET Labs, Inc. ECO, exposed to fresh and artificially weathered crude oil, were determined. Sensors were standardized against known oil volumes and total petroleum hydrocarbons and benzene-toluene-ethylbenzene-xylene measurements-both collected during spills, providing oil estimates during wave tank dilution experiments. All sensors estimated oil concentrations down to 300 ppb oil, refuting previous reports. Sensor performance results assist interpretation of DWH oil spill data and formulating future protocols. PMID:24377909

  4. Advanced material testing in support of accurate sheet metal forming simulations

    NASA Astrophysics Data System (ADS)

    Kuwabara, Toshihiko

    2013-05-01

    This presentation is a review of experimental methods for accurately measuring and modeling the anisotropic plastic deformation behavior of metal sheets under a variety of loading paths: biaxial compression test, hydraulic bulge test, biaxial tension test using a cruciform specimen, multiaxial tube expansion test using a closed-loop electrohydraulic testing machine for the measurement of forming limit strains and stresses, combined tension-shear test, and in-plane stress reversal test. Observed material responses are compared with predictions using phenomenological plasticity models to highlight the importance of accurate material testing. Special attention is paid to the plastic deformation behavior of sheet metals commonly used in industry, and to verifying the validity of constitutive models based on anisotropic yield functions at a large plastic strain range. The effects of using appropriate material models on the improvement of predictive accuracy for forming defects, such as springback and fracture, are also presented.

  5. Bayesian parameter estimation of a k-ε model for accurate jet-in-crossflow simulations

    DOE PAGES

    Ray, Jaideep; Lefantzi, Sophia; Arunajatesan, Srinivasan; Dechant, Lawrence

    2016-05-31

    Reynolds-averaged Navier–Stokes models are not very accurate for high-Reynolds-number compressible jet-in-crossflow interactions. The inaccuracy arises from the use of inappropriate model parameters and model-form errors in the Reynolds-averaged Navier–Stokes model. In this study, the hypothesis is pursued that Reynolds-averaged Navier–Stokes predictions can be significantly improved by using parameters inferred from experimental measurements of a supersonic jet interacting with a transonic crossflow.

  6. From oil shortage to oil glut: simulation of growth prospects in the Nigerian economy

    SciTech Connect

    Olofin, S.; Iyaniwura, J.O.

    1983-11-01

    During the 1970s, the economy of Nigeria provided one of the most interesting cases of development financed through oil revenue. Between 1970 and 1980, the country's GNP grew at an outstanding rate, but after the transition from oil shortage to oil glut, the economy of Nigeria ran into dramatic financial difficulties, which are now placing major constraints to its development. To investigate the transition from an oil-based economy to a stage characterized by greater diversification of exports and more balanced sectoral growth, a model has been built by the University of Ibadan in Nigeria. The model was developed in association with Project LINK staffing for the future inclusion in the Project. According to the finding presented in the study, the annual growth rate of GDP of Nigeria between 1980 and 1988 will be around 2.5%. To compensate the drop of the foreign-exchange earnings caused by the contraction of oil prices and demand, a vigorous export drive of agricultural products is simulated. 8 references, 7 figures, 4 tables.

  7. The Space-Time Conservative Schemes for Large-Scale, Time-Accurate Flow Simulations with Tetrahedral Meshes

    NASA Technical Reports Server (NTRS)

    Venkatachari, Balaji Shankar; Streett, Craig L.; Chang, Chau-Lyan; Friedlander, David J.; Wang, Xiao-Yen; Chang, Sin-Chung

    2016-01-01

    Despite decades of development of unstructured mesh methods, high-fidelity time-accurate simulations are still predominantly carried out on structured, or unstructured hexahedral meshes by using high-order finite-difference, weighted essentially non-oscillatory (WENO), or hybrid schemes formed by their combinations. In this work, the space-time conservation element solution element (CESE) method is used to simulate several flow problems including supersonic jet/shock interaction and its impact on launch vehicle acoustics, and direct numerical simulations of turbulent flows using tetrahedral meshes. This paper provides a status report for the continuing development of the space-time conservation element solution element (CESE) numerical and software framework under the Revolutionary Computational Aerosciences (RCA) project. Solution accuracy and large-scale parallel performance of the numerical framework is assessed with the goal of providing a viable paradigm for future high-fidelity flow physics simulations.

  8. Evaluation of a Second-Order Accurate Navier-Stokes Code for Detached Eddy Simulation Past a Circular Cylinder

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Singer, Bart A.

    2003-01-01

    We evaluate the applicability of a production computational fluid dynamics code for conducting detached eddy simulation for unsteady flows. A second-order accurate Navier-Stokes code developed at NASA Langley Research Center, known as TLNS3D, is used for these simulations. We focus our attention on high Reynolds number flow (Re = 5 x 10(sup 4) - 1.4 x 10(sup 5)) past a circular cylinder to simulate flows with large-scale separations. We consider two types of flow situations: one in which the flow at the separation point is laminar, and the other in which the flow is already turbulent when it detaches from the surface of the cylinder. Solutions are presented for two- and three-dimensional calculations using both the unsteady Reynolds-averaged Navier-Stokes paradigm and the detached eddy simulation treatment. All calculations use the standard Spalart-Allmaras turbulence model as the base model.

  9. Accurate time delay technology in simulated test for high precision laser range finder

    NASA Astrophysics Data System (ADS)

    Chen, Zhibin; Xiao, Wenjian; Wang, Weiming; Xue, Mingxi

    2015-10-01

    With the continuous development of technology, the ranging accuracy of pulsed laser range finder (LRF) is higher and higher, so the maintenance demand of LRF is also rising. According to the dominant ideology of "time analog spatial distance" in simulated test for pulsed range finder, the key of distance simulation precision lies in the adjustable time delay. By analyzing and comparing the advantages and disadvantages of fiber and circuit delay, a method was proposed to improve the accuracy of the circuit delay without increasing the count frequency of the circuit. A high precision controllable delay circuit was designed by combining the internal delay circuit and external delay circuit which could compensate the delay error in real time. And then the circuit delay accuracy could be increased. The accuracy of the novel circuit delay methods proposed in this paper was actually measured by a high sampling rate oscilloscope actual measurement. The measurement result shows that the accuracy of the distance simulated by the circuit delay is increased from +/- 0.75m up to +/- 0.15m. The accuracy of the simulated distance is greatly improved in simulated test for high precision pulsed range finder.

  10. A CUDA based parallel multi-phase oil reservoir simulator

    NASA Astrophysics Data System (ADS)

    Zaza, Ayham; Awotunde, Abeeb A.; Fairag, Faisal A.; Al-Mouhamed, Mayez A.

    2016-09-01

    Forward Reservoir Simulation (FRS) is a challenging process that models fluid flow and mass transfer in porous media to draw conclusions about the behavior of certain flow variables and well responses. Besides the operational cost associated with matrix assembly, FRS repeatedly solves huge and computationally expensive sparse, ill-conditioned and unsymmetrical linear system. Moreover, as the computation for practical reservoir dimensions lasts for long times, speeding up the process by taking advantage of parallel platforms is indispensable. By considering the state of art advances in massively parallel computing and the accompanying parallel architecture, this work aims primarily at developing a CUDA-based parallel simulator for oil reservoir. In addition to the initial reported 33 times speed gain compared to the serial version, running experiments showed that BiCGSTAB is a stable and fast solver which could be incorporated in such simulations instead of the more expensive, storage demanding and usually utilized GMRES.

  11. Enabling R&D for accurate simulation of non-ideal explosives.

    SciTech Connect

    Aidun, John Bahram; Thompson, Aidan Patrick; Schmitt, Robert Gerard

    2010-09-01

    We implemented two numerical simulation capabilities essential to reliably predicting the effect of non-ideal explosives (NXs). To begin to be able to treat the multiple, competing, multi-step reaction paths and slower kinetics of NXs, Sandia's CTH shock physics code was extended to include the TIGER thermochemical equilibrium solver as an in-line routine. To facilitate efficient exploration of reaction pathways that need to be identified for the CTH simulations, we implemented in Sandia's LAMMPS molecular dynamics code the MSST method, which is a reactive molecular dynamics technique for simulating steady shock wave response. Our preliminary demonstrations of these two capabilities serve several purposes: (i) they demonstrate proof-of-principle for our approach; (ii) they provide illustration of the applicability of the new functionality; and (iii) they begin to characterize the use of the new functionality and identify where improvements will be needed for the ultimate capability to meet national security needs. Next steps are discussed.

  12. OBSERVING SIMULATED PROTOSTARS WITH OUTFLOWS: HOW ACCURATE ARE PROTOSTELLAR PROPERTIES INFERRED FROM SEDs?

    SciTech Connect

    Offner, Stella S. R.; Robitaille, Thomas P.; Hansen, Charles E.; Klein, Richard I.; McKee, Christopher F.

    2012-07-10

    The properties of unresolved protostars and their local environment are frequently inferred from spectral energy distributions (SEDs) using radiative transfer modeling. In this paper, we use synthetic observations of realistic star formation simulations to evaluate the accuracy of properties inferred from fitting model SEDs to observations. We use ORION, an adaptive mesh refinement (AMR) three-dimensional gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent molecular cloud including the effects of protostellar outflows. To obtain the dust temperature distribution and SEDs of the forming protostars, we post-process the simulations using HYPERION, a state-of-the-art Monte Carlo radiative transfer code. We find that the ORION and HYPERION dust temperatures typically agree within a factor of two. We compare synthetic SEDs of embedded protostars for a range of evolutionary times, simulation resolutions, aperture sizes, and viewing angles. We demonstrate that complex, asymmetric gas morphology leads to a variety of classifications for individual objects as a function of viewing angle. We derive best-fit source parameters for each SED through comparison with a pre-computed grid of radiative transfer models. While the SED models correctly identify the evolutionary stage of the synthetic sources as embedded protostars, we show that the disk and stellar parameters can be very discrepant from the simulated values, which is expected since the disk and central source are obscured by the protostellar envelope. Parameters such as the stellar accretion rate, stellar mass, and disk mass show better agreement, but can still deviate significantly, and the agreement may in some cases be artificially good due to the limited range of parameters in the set of model SEDs. Lack of correlation between the model and simulation properties in many individual instances cautions against overinterpreting properties inferred from SEDs for unresolved protostellar

  13. Development of a Godunov-type model for the accurate simulation of dispersion dominated waves

    NASA Astrophysics Data System (ADS)

    Bradford, Scott F.

    2016-10-01

    A new numerical model based on the Navier-Stokes equations is presented for the simulation of dispersion dominated waves. The equations are solved by splitting the pressure into hydrostatic and non-hydrostatic components. The Godunov approach is utilized to solve the hydrostatic flow equations and the resulting velocity field is then corrected to be divergence free. Alternative techniques for the time integration of the non-hydrostatic pressure gradients are presented and investigated in order to improve the accuracy of dispersion dominated wave simulations. Numerical predictions are compared with analytical solutions and experimental data for test cases involving standing, shoaling, refracting, and breaking waves.

  14. Accurate treatments of electrostatics for computer simulations of biological systems: A brief survey of developments and existing problems

    NASA Astrophysics Data System (ADS)

    Yi, Sha-Sha; Pan, Cong; Hu, Zhong-Han

    2015-12-01

    Modern computer simulations of biological systems often involve an explicit treatment of the complex interactions among a large number of molecules. While it is straightforward to compute the short-ranged Van der Waals interaction in classical molecular dynamics simulations, it has been a long-lasting issue to develop accurate methods for the longranged Coulomb interaction. In this short review, we discuss three types of methodologies for the accurate treatment of electrostatics in simulations of explicit molecules: truncation-type methods, Ewald-type methods, and mean-field-type methods. Throughout the discussion, we brief the formulations and developments of these methods, emphasize the intrinsic connections among the three types of methods, and focus on the existing problems which are often associated with the boundary conditions of electrostatics. This brief survey is summarized with a short perspective on future trends along the method developments and applications in the field of biological simulations. Project supported by the National Natural Science Foundation of China (Grant Nos. 91127015 and 21522304) and the Open Project from the State Key Laboratory of Theoretical Physics, and the Innovation Project from the State Key Laboratory of Supramolecular Structure and Materials.

  15. The prestige oil spill. I. Biodegradation of a heavy fuel oil under simulated conditions.

    PubMed

    Díez, Sergi; Sabatté, Jordi; Viñas, Marc; Bayona, Josep M; Solanas, Anna M; Albaigés, Joan

    2005-09-01

    In vitro biodegradation of the Prestige heavy fuel oil has been carried out using two microbial consortia obtained by enrichment in different substrates to simulate its environmental fate and potential utility for bioremediation. Different conditions, such as incubation time (i.e., 20 or 40 d), oil weathering, and addition of an oleophilic fertilizer (S200), were evaluated. Weathering slowed down the degradation of the fuel oil, probably because of the loss of lower and more labile components, but the addition of S200 enhanced significantly the extension of the biodegradation. n-Alkanes, alkylcyclohexanes, alkylbenzenes, and the two- to three-ring polycyclic aromatic hydrocarbons (PAHs) were degraded in 20 or 40 d of incubation of the original oil, whereas the biodegradation efficiency decreased for higher PAHs and with the increase of alkylation. Molecular markers were degraded according to the following sequence: Acyclic isoprenoids > diasteranes > C27-steranes > betabeta-steranes > homohopanes > monoaromatic steranes > triaromatic steranes. Isomeric selectivity was observed within the C1- and C2-phenanthrenes, dibenzothiophenes, pyrenes, and chrysenes, providing source and weathering indices for the characterization of the heavy oil spill. Acyclic isoprenoids, C27-steranes, C1- and C2-naphthalenes, phenanthrenes, and dibenzothiophenes were degraded completely when S200 was used. The ratios of the C2- and C3-alkyl homologues of fluoranthene/pyrene and chrysene/benzo[a]anthracene are proposed as source ratios in moderately degraded oils. The 4-methylpyrene and 3-methylchrysene were refractory enough to serve as conserved internal markers in assessing the degradation of the aromatic fraction in a manner similar to that of hopane, as used for the aliphatic fraction.

  16. Chemically Accurate Simulation of a Polyatomic Molecule-Metal Surface Reaction

    PubMed Central

    2016-01-01

    Although important to heterogeneous catalysis, the ability to accurately model reactions of polyatomic molecules with metal surfaces has not kept pace with developments in gas phase dynamics. Partnering the specific reaction parameter (SRP) approach to density functional theory with ab initio molecular dynamics (AIMD) extends our ability to model reactions with metals with quantitative accuracy from only the lightest reactant, H2, to essentially all molecules. This is demonstrated with AIMD calculations on CHD3 + Ni(111) in which the SRP functional is fitted to supersonic beam experiments, and validated by showing that AIMD with the resulting functional reproduces initial-state selected sticking measurements with chemical accuracy (4.2 kJ/mol ≈ 1 kcal/mol). The need for only semilocal exchange makes our scheme computationally tractable for dissociation on transition metals. PMID:27284787

  17. An Accurately Stable Thermo-Hydro-Mechanical Model for Geo-Environmental Simulations

    NASA Astrophysics Data System (ADS)

    Gambolati, G.; Castelletto, N.; Ferronato, M.

    2011-12-01

    In real-world applications involving complex 3D heterogeneous domains the use of advanced numerical algorithms is of paramount importance to stabily, accurately and efficiently solve the coupled system of partial differential equations governing the mass and the energy balance in deformable porous media. The present communication discusses a novel coupled 3-D numerical model based on a suitable combination of Finite Elements (FEs), Mixed FEs (MFEs), and Finite Volumes (FVs) developed with the aim at stabilizing the numerical solution. Elemental pressures and temperatures, nodal displacements and face normal Darcy and Fourier fluxes are the selected primary variables. Such an approach provides an element-wise conservative velocity field, with both pore pressure and stress having the same order of approximation, and allows for the accurate prediction of sharp temperature convective fronts. In particular, the flow-deformation problem is addressed jointly by FEs and MFEs and is coupled to the heat transfer equation using an ad hoc time splitting technique that separates the time temperature evolution into two partial differential equations, accounting for the convective and the diffusive contribution, respectively. The convective part is addressed by a FV scheme which proves effective in treating sharp convective fronts, while the diffusive part is solved by a MFE formulation. A staggered technique is then implemented for the global solution of the coupled thermo-hydro-mechanical problem, solving iteratively the flow-deformation and the heat transport at each time step. Finally, the model is successfully experimented with in realistic applications dealing with geothermal energy extraction and injection.

  18. Accurate reaction-diffusion operator splitting on tetrahedral meshes for parallel stochastic molecular simulations

    NASA Astrophysics Data System (ADS)

    Hepburn, I.; Chen, W.; De Schutter, E.

    2016-08-01

    Spatial stochastic molecular simulations in biology are limited by the intense computation required to track molecules in space either in a discrete time or discrete space framework, which has led to the development of parallel methods that can take advantage of the power of modern supercomputers in recent years. We systematically test suggested components of stochastic reaction-diffusion operator splitting in the literature and discuss their effects on accuracy. We introduce an operator splitting implementation for irregular meshes that enhances accuracy with minimal performance cost. We test a range of models in small-scale MPI simulations from simple diffusion models to realistic biological models and find that multi-dimensional geometry partitioning is an important consideration for optimum performance. We demonstrate performance gains of 1-3 orders of magnitude in the parallel implementation, with peak performance strongly dependent on model specification.

  19. Accurate reaction-diffusion operator splitting on tetrahedral meshes for parallel stochastic molecular simulations.

    PubMed

    Hepburn, I; Chen, W; De Schutter, E

    2016-08-01

    Spatial stochastic molecular simulations in biology are limited by the intense computation required to track molecules in space either in a discrete time or discrete space framework, which has led to the development of parallel methods that can take advantage of the power of modern supercomputers in recent years. We systematically test suggested components of stochastic reaction-diffusion operator splitting in the literature and discuss their effects on accuracy. We introduce an operator splitting implementation for irregular meshes that enhances accuracy with minimal performance cost. We test a range of models in small-scale MPI simulations from simple diffusion models to realistic biological models and find that multi-dimensional geometry partitioning is an important consideration for optimum performance. We demonstrate performance gains of 1-3 orders of magnitude in the parallel implementation, with peak performance strongly dependent on model specification. PMID:27497550

  20. Accurate reaction-diffusion operator splitting on tetrahedral meshes for parallel stochastic molecular simulations.

    PubMed

    Hepburn, I; Chen, W; De Schutter, E

    2016-08-01

    Spatial stochastic molecular simulations in biology are limited by the intense computation required to track molecules in space either in a discrete time or discrete space framework, which has led to the development of parallel methods that can take advantage of the power of modern supercomputers in recent years. We systematically test suggested components of stochastic reaction-diffusion operator splitting in the literature and discuss their effects on accuracy. We introduce an operator splitting implementation for irregular meshes that enhances accuracy with minimal performance cost. We test a range of models in small-scale MPI simulations from simple diffusion models to realistic biological models and find that multi-dimensional geometry partitioning is an important consideration for optimum performance. We demonstrate performance gains of 1-3 orders of magnitude in the parallel implementation, with peak performance strongly dependent on model specification.

  1. Pre-Stall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation

    NASA Technical Reports Server (NTRS)

    Chen, Jen-Ping; Hathaway, Michael D.; Herrick, Gregory P.

    2008-01-01

    CFD calculations using high-performance parallel computing were conducted to simulate the pre-stall flow of a transonic compressor stage, NASA compressor Stage 35. The simulations were run with a full-annulus grid that models the 3D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation demonstrates the development of the rotating stall from the growth of instabilities. Pressure-rise performance and pressure traces are compared with published experimental data before the study of flow evolution prior to the rotating stall. Spatial FFT analysis of the flow indicates a rotating long-length disturbance of one rotor circumference, which is followed by a spike-type breakdown. The analysis also links the long-length wave disturbance with the initiation of the spike inception. The spike instabilities occur when the trajectory of the tip clearance flow becomes perpendicular to the axial direction. When approaching stall, the passage shock changes from a single oblique shock to a dual-shock, which distorts the perpendicular trajectory of the tip clearance vortex but shows no evidence of flow separation that may contribute to stall.

  2. Utilizing fast multipole expansions for efficient and accurate quantum-classical molecular dynamics simulations.

    PubMed

    Schwörer, Magnus; Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul

    2015-03-14

    Recently, a novel approach to hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations has been suggested [Schwörer et al., J. Chem. Phys. 138, 244103 (2013)]. Here, the forces acting on the atoms are calculated by grid-based density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 10(3)-10(5) molecules as negative gradients of a DFT/PMM hybrid Hamiltonian. The electrostatic interactions are efficiently described by a hierarchical fast multipole method (FMM). Adopting recent progress of this FMM technique [Lorenzen et al., J. Chem. Theory Comput. 10, 3244 (2014)], which particularly entails a strictly linear scaling of the computational effort with the system size, and adapting this revised FMM approach to the computation of the interactions between the DFT and PMM fragments of a simulation system, here, we show how one can further enhance the efficiency and accuracy of such DFT/PMM-MD simulations. The resulting gain of total performance, as measured for alanine dipeptide (DFT) embedded in water (PMM) by the product of the gains in efficiency and accuracy, amounts to about one order of magnitude. We also demonstrate that the jointly parallelized implementation of the DFT and PMM-MD parts of the computation enables the efficient use of high-performance computing systems. The associated software is available online. PMID:25770527

  3. Utilizing fast multipole expansions for efficient and accurate quantum-classical molecular dynamics simulations

    SciTech Connect

    Schwörer, Magnus; Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul

    2015-03-14

    Recently, a novel approach to hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations has been suggested [Schwörer et al., J. Chem. Phys. 138, 244103 (2013)]. Here, the forces acting on the atoms are calculated by grid-based density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 10{sup 3}-10{sup 5} molecules as negative gradients of a DFT/PMM hybrid Hamiltonian. The electrostatic interactions are efficiently described by a hierarchical fast multipole method (FMM). Adopting recent progress of this FMM technique [Lorenzen et al., J. Chem. Theory Comput. 10, 3244 (2014)], which particularly entails a strictly linear scaling of the computational effort with the system size, and adapting this revised FMM approach to the computation of the interactions between the DFT and PMM fragments of a simulation system, here, we show how one can further enhance the efficiency and accuracy of such DFT/PMM-MD simulations. The resulting gain of total performance, as measured for alanine dipeptide (DFT) embedded in water (PMM) by the product of the gains in efficiency and accuracy, amounts to about one order of magnitude. We also demonstrate that the jointly parallelized implementation of the DFT and PMM-MD parts of the computation enables the efficient use of high-performance computing systems. The associated software is available online.

  4. Accurate simulation of the electron cloud in the Fermilab Main Injector with VORPAL

    SciTech Connect

    Lebrun, Paul L.G.; Spentzouris, Panagiotis; Cary, John R.; Stoltz, Peter; Veitzer, Seth A.; /Tech-X, Boulder

    2011-01-01

    We present results from a precision simulation of the electron cloud (EC) in the Fermilab Main Injector using the code VORPAL. This is a fully 3d and self consistent treatment of the EC. Both distributions of electrons in 6D phase-space and E.M. field maps have been generated. This has been done for various configurations of the magnetic fields found around the machine have been studied. Plasma waves associated to the fluctuation density of the cloud have been analyzed. Our results are compared with those obtained with the POSINST code. The response of a Retarding Field Analyzer (RFA) to the EC has been simulated, as well as the more challenging microwave absorption experiment. Definite predictions of their exact response are difficult to obtain,mostly because of the uncertainties in the secondary emission yield and, in the case of the RFA, because of the sensitivity of the electron collection efficiency to unknown stray magnetic fields. Nonetheless, our simulations do provide guidance to the experimental program.

  5. Three dimensional simulation of transport and fate of oil spill under wave induced circulation.

    PubMed

    Liu, Tianyi; Peter Sheng, Y

    2014-03-15

    An oil spill model is developed and coupled to a current-wave model to simulate oil spill transport in aquatic environments where waves are present. The oil spill model incorporates physical-chemical processes of oil spill, and simulates oil slick transport by a circulation-driven Lagrangian Parcel model. Using the coupled oil spill model and the current-wave model CH3D-SWAN, a laboratory observed wave induced circulation and oil slick evolution are successfully simulated, while different current-wave coupling schemes generate different flow patterns and oil slick evolution. The modeling system is also shown to simulate Langmuir circulation and resulting oil slicks. Hypothetical scenarios of oil spill near Virginia coast during Hurricane Isabel and Irene are simulated using the oil spill model and the CH3D-Storm Surge Modeling System to assess the role of storm waves during oil spill. The spill area is significantly larger when storm waves are considered, implying waves significantly increase oil spill dispersion.

  6. Optimization of tissue physical parameters for accurate temperature estimation from finite-element simulation of radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Subramanian, Swetha; Mast, T. Douglas

    2015-09-01

    Computational finite element models are commonly used for the simulation of radiofrequency ablation (RFA) treatments. However, the accuracy of these simulations is limited by the lack of precise knowledge of tissue parameters. In this technical note, an inverse solver based on the unscented Kalman filter (UKF) is proposed to optimize values for specific heat, thermal conductivity, and electrical conductivity resulting in accurately simulated temperature elevations. A total of 15 RFA treatments were performed on ex vivo bovine liver tissue. For each RFA treatment, 15 finite-element simulations were performed using a set of deterministically chosen tissue parameters to estimate the mean and variance of the resulting tissue ablation. The UKF was implemented as an inverse solver to recover the specific heat, thermal conductivity, and electrical conductivity corresponding to the measured area of the ablated tissue region, as determined from gross tissue histology. These tissue parameters were then employed in the finite element model to simulate the position- and time-dependent tissue temperature. Results show good agreement between simulated and measured temperature.

  7. Optimization of tissue physical parameters for accurate temperature estimation from finite-element simulation of radiofrequency ablation.

    PubMed

    Subramanian, Swetha; Mast, T Douglas

    2015-10-01

    Computational finite element models are commonly used for the simulation of radiofrequency ablation (RFA) treatments. However, the accuracy of these simulations is limited by the lack of precise knowledge of tissue parameters. In this technical note, an inverse solver based on the unscented Kalman filter (UKF) is proposed to optimize values for specific heat, thermal conductivity, and electrical conductivity resulting in accurately simulated temperature elevations. A total of 15 RFA treatments were performed on ex vivo bovine liver tissue. For each RFA treatment, 15 finite-element simulations were performed using a set of deterministically chosen tissue parameters to estimate the mean and variance of the resulting tissue ablation. The UKF was implemented as an inverse solver to recover the specific heat, thermal conductivity, and electrical conductivity corresponding to the measured area of the ablated tissue region, as determined from gross tissue histology. These tissue parameters were then employed in the finite element model to simulate the position- and time-dependent tissue temperature. Results show good agreement between simulated and measured temperature. PMID:26352462

  8. Accurate simulation of MPPT methods performance when applied to commercial photovoltaic panels.

    PubMed

    Cubas, Javier; Pindado, Santiago; Sanz-Andrés, Ángel

    2015-01-01

    A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions.

  9. Accurate simulation of MPPT methods performance when applied to commercial photovoltaic panels.

    PubMed

    Cubas, Javier; Pindado, Santiago; Sanz-Andrés, Ángel

    2015-01-01

    A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions. PMID:25874262

  10. Accurate Simulation of MPPT Methods Performance When Applied to Commercial Photovoltaic Panels

    PubMed Central

    2015-01-01

    A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions. PMID:25874262

  11. Large-scale oil spill simulation using the lattice Boltzmann method, validation on the Lebanon oil spill case.

    PubMed

    Maslo, Aljaž; Panjan, Jože; Žagar, Dušan

    2014-07-15

    This paper tests the adequacy of using the lattice Boltzmann method in large-scale oil spill modelling, such as the Lebanon oil spill. Several numerical experiments were performed in order to select the most appropriate lattice and to decide between the single- and two-relaxation time models. Large-scale oil spills require simulations with short computational times. In order to speed up the computation and preserve adequate accuracy of the model, five different flux limiting interpolation techniques were compared and evaluated. The model was validated on the Lebanon oil spill with regard to the oil-slick position and concentrations in the sea, and the beaching area on the coast. Good agreement with satellite images of the slick and field data on beaching was achieved. The main advantages of the applied method are the capability of simulating very low oil concentrations and computational times that are by an order of magnitude shorter compared to similar models.

  12. Consistent Multigroup Theory Enabling Accurate Course-Group Simulation of Gen IV Reactors

    SciTech Connect

    Rahnema, Farzad; Haghighat, Alireza; Ougouag, Abderrafi

    2013-11-29

    The objective of this proposal is the development of a consistent multi-group theory that accurately accounts for the energy-angle coupling associated with collapsed-group cross sections. This will allow for coarse-group transport and diffusion theory calculations that exhibit continuous energy accuracy and implicitly treat cross- section resonances. This is of particular importance when considering the highly heterogeneous and optically thin reactor designs within the Next Generation Nuclear Plant (NGNP) framework. In such reactors, ignoring the influence of anisotropy in the angular flux on the collapsed cross section, especially at the interface between core and reflector near which control rods are located, results in inaccurate estimates of the rod worth, a serious safety concern. The scope of this project will include the development and verification of a new multi-group theory enabling high-fidelity transport and diffusion calculations in coarse groups, as well as a methodology for the implementation of this method in existing codes. This will allow for a higher accuracy solution of reactor problems while using fewer groups and will reduce the computational expense. The proposed research represents a fundamental advancement in the understanding and improvement of multi- group theory for reactor analysis.

  13. Simulating Dissolution of Intravitreal Triamcinolone Acetonide Suspensions in an Anatomically Accurate Rabbit Eye Model

    PubMed Central

    Horner, Marc; Muralikrishnan, R.

    2010-01-01

    ABSTRACT Purpose A computational fluid dynamics (CFD) study examined the impact of particle size on dissolution rate and residence of intravitreal suspension depots of Triamcinolone Acetonide (TAC). Methods A model for the rabbit eye was constructed using insights from high-resolution NMR imaging studies (Sawada 2002). The current model was compared to other published simulations in its ability to predict clearance of various intravitreally injected materials. Suspension depots were constructed explicitly rendering individual particles in various configurations: 4 or 16 mg drug confined to a 100 μL spherical depot, or 4 mg exploded to fill the entire vitreous. Particle size was reduced systematically in each configuration. The convective diffusion/dissolution process was simulated using a multiphase model. Results Release rate became independent of particle diameter below a certain value. The size-independent limits occurred for particle diameters ranging from 77 to 428 μM depending upon the depot configuration. Residence time predicted for the spherical depots in the size-independent limit was comparable to that observed in vivo. Conclusions Since the size-independent limit was several-fold greater than the particle size of commercially available pharmaceutical TAC suspensions, differences in particle size amongst such products are predicted to be immaterial to their duration or performance. PMID:20467888

  14. How accurate are volcanic ash simulations of the 2010 Eyjafjallajökull eruption?

    NASA Astrophysics Data System (ADS)

    Dacre, Helen; Harvey, Natalie; Webley, Peter; Morton, Don

    2016-04-01

    In the event of a volcanic eruption the decision to close airspace is based on forecast ash maps, produced using volcanic ash transport and dispersion models. In this paper we quantitatively evaluate the spatial skill of volcanic ash simulations using satellite retrievals of ash from the Eyjafjallajökull eruption during the period from 7-16 May 2010. We find that at the start of this period, 7-10 May, the model (FLEXPART) has excellent skill and can predict the spatial distribution of the satellite retrieved ash to within 0.5°× 0.5° lat/lon. However, on the 10 May there is a decrease in the spatial accuracy of the model, to 2.5°× 2.5° lat/lon, and between 11-12 May the simulated ash location errors grow rapidly. On the 11 May ash is located close to a bifurcation point in the atmosphere, resulting in a rapid divergence in the modeled and satellite ash locations. In general, the model skill reduces as the residence time of ash increases. However, the error growth is not always steady. Rapid increases in error growth are linked to critical points in the ash trajectories. Ensemble modeling using perturbed meteorological data would help to represent this uncertainty and assimilation of satellite ash data would help to reduce uncertainty in volcanic ash forecasts.

  15. Accurate and efficient integration for molecular dynamics simulations at constant temperature and pressure.

    PubMed

    Lippert, Ross A; Predescu, Cristian; Ierardi, Douglas J; Mackenzie, Kenneth M; Eastwood, Michael P; Dror, Ron O; Shaw, David E

    2013-10-28

    In molecular dynamics simulations, control over temperature and pressure is typically achieved by augmenting the original system with additional dynamical variables to create a thermostat and a barostat, respectively. These variables generally evolve on timescales much longer than those of particle motion, but typical integrator implementations update the additional variables along with the particle positions and momenta at each time step. We present a framework that replaces the traditional integration procedure with separate barostat, thermostat, and Newtonian particle motion updates, allowing thermostat and barostat updates to be applied infrequently. Such infrequent updates provide a particularly substantial performance advantage for simulations parallelized across many computer processors, because thermostat and barostat updates typically require communication among all processors. Infrequent updates can also improve accuracy by alleviating certain sources of error associated with limited-precision arithmetic. In addition, separating the barostat, thermostat, and particle motion update steps reduces certain truncation errors, bringing the time-average pressure closer to its target value. Finally, this framework, which we have implemented on both general-purpose and special-purpose hardware, reduces software complexity and improves software modularity.

  16. TRIM—3D: a three-dimensional model for accurate simulation of shallow water flow

    USGS Publications Warehouse

    Casulli, Vincenzo; Bertolazzi, Enrico; Cheng, Ralph T.

    1993-01-01

    A semi-implicit finite difference formulation for the numerical solution of three-dimensional tidal circulation is discussed. The governing equations are the three-dimensional Reynolds equations in which the pressure is assumed to be hydrostatic. A minimal degree of implicitness has been introduced in the finite difference formula so that the resulting algorithm permits the use of large time steps at a minimal computational cost. This formulation includes the simulation of flooding and drying of tidal flats, and is fully vectorizable for an efficient implementation on modern vector computers. The high computational efficiency of this method has made it possible to provide the fine details of circulation structure in complex regions that previous studies were unable to obtain. For proper interpretation of the model results suitable interactive graphics is also an essential tool.

  17. Simulating Expert Clinical Comprehension: Adapting Latent Semantic Analysis to Accurately Extract Clinical Concepts from Psychiatric Narrative

    PubMed Central

    Cohen, Trevor; Blatter, Brett; Patel, Vimla

    2008-01-01

    Cognitive studies reveal that less-than-expert clinicians are less able to recognize meaningful patterns of data in clinical narratives. Accordingly, psychiatric residents early in training fail to attend to information that is relevant to diagnosis and the assessment of dangerousness. This manuscript presents cognitively motivated methodology for the simulation of expert ability to organize relevant findings supporting intermediate diagnostic hypotheses. Latent Semantic Analysis is used to generate a semantic space from which meaningful associations between psychiatric terms are derived. Diagnostically meaningful clusters are modeled as geometric structures within this space and compared to elements of psychiatric narrative text using semantic distance measures. A learning algorithm is defined that alters components of these geometric structures in response to labeled training data. Extraction and classification of relevant text segments is evaluated against expert annotation, with system-rater agreement approximating rater-rater agreement. A range of biomedical informatics applications for these methods are suggested. PMID:18455483

  18. Evaluation of the EURO-CORDEX RCMs to accurately simulate the Etesian wind system

    NASA Astrophysics Data System (ADS)

    Dafka, Stella; Xoplaki, Elena; Toreti, Andrea; Zanis, Prodromos; Tyrlis, Evangelos; Luterbacher, Jürg

    2016-04-01

    The Etesians are among the most persistent regional scale wind systems in the lower troposphere that blow over the Aegean Sea during the extended summer season. ΑAn evaluation of the high spatial resolution, EURO-CORDEX Regional Climate Models (RCMs) is here presented. The study documents the performance of the individual models in representing the basic spatiotemporal pattern of the Etesian wind system for the period 1989-2004. The analysis is mainly focused on evaluating the abilities of the RCMs in simulating the surface wind over the Aegean Sea and the associated large scale atmospheric circulation. Mean Sea Level Pressure (SLP), wind speed and geopotential height at 500 hPa are used. The simulated results are validated against reanalysis datasets (20CR-v2c and ERA20-C) and daily observational measurements (12:00 UTC) from the mainland Greece and Aegean Sea. The analysis highlights the general ability of the RCMs to capture the basic features of the Etesians, but also indicates considerable deficiencies for selected metrics, regions and subperiods. Some of these deficiencies include the significant underestimation (overestimation) of the mean SLP in the northeastern part of the analysis domain in all subperiods (for May and June) when compared to 20CR-v2c (ERA20-C), the significant overestimation of the anomalous ridge over the Balkans and central Europe and the underestimation of the wind speed over the Aegean Sea. Future work will include an assessment of the Etesians for the next decades using EURO-CORDEX projections under different RCP scenarios and estimate the future potential for wind energy production.

  19. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: An Accurate Image Simulation Method for High-Order Laue Zone Effects

    NASA Astrophysics Data System (ADS)

    Cai, Can-Ying; Zeng, Song-Jun; Liu, Hong-Rong; Yang, Qi-Bin

    2008-05-01

    A completely different formulation for simulation of the high order Laue zone (HOLZ) diffractions is derived. It refers to the new method, i.e. the Taylor series (TS) method. To check the validity and accuracy of the TS method, we take polyvinglidene fluoride (PVDF) crystal as an example to calculate the exit wavefunction by the conventional multi-slice (CMS) method and the TS method. The calculated results show that the TS method is much more accurate than the CMS method and is independent of the slice thicknesses. Moreover, the pure first order Laue zone wavefunction by the TS method can reflect the major potential distribution of the first reciprocal plane.

  20. Accurate simulation of near-wall turbulence over a compliant tensegrity fabric

    NASA Astrophysics Data System (ADS)

    Luo, Haoxiang; Bewley, Thomas R.

    2005-05-01

    This paper presents a new class of compliant surfaces, dubbed tensegrity fabrics, for the problem of reducing the drag induced by near-wall turbulent flows. The substructure upon which this compliant surface is built is based on the "tensegrity" structural paradigm, and is formed as a stable pretensioned network of compressive members ("bars") interconnected by tensile members ("tendons"). Compared with existing compliant surface studies, most of which are based on spring-supported plates or membranes, tensegrity fabrics appear to be better configured to respond to the shear stress fluctuations (in addition to the pressure fluctuations) generated by near-wall turbulence. As a result, once the several parameters affecting the compliance characteristics of the structure are tuned appropriately, the tensegrity fabric might exhibit an improved capacity for dampening the fluctuations of near-wall turbulence, thereby reducing drag. This paper improves our previous work (SPIE Paper 5049-57) and uses a 3D time-dependent coordinate transformation in the flow simulations to account for the motion of the channel walls, and the Cartesian components of the velocity are used as the flow variables. For the spatial discretization, a dealiased pseudospectral scheme is used in the homogeneous directions and a second-order finite difference scheme is used in the wall-normal direction. The code is first validated with several benchmark results that are available in the published literature for flows past both stationary and nonstationary walls. Direct numerical simulations of turbulent flows at Re_tau=150 over the compliant tensegrity fabric are then presented. It is found that, when the stiffness, mass, damping, and orientation of the members of the the unit cell defining the tensegrity fabric are selected appropriately, the near-wall statistics of the turbulence are altered significantly. The flow/structure interface is found to form streamwise-travelling waves reminiscent of those

  1. Accurate crystal molecular dynamics simulations using particle-mesh-Ewald: RNA dinucleotides — ApU and GpC

    NASA Astrophysics Data System (ADS)

    Lee, Hsing; Darden, Thomas; Pedersen, Lee

    1995-09-01

    Long molecular dynamics (MD) simulations for two crystal RNA dinucleotides ApU (2.0 ns) and GpC (1.5 ns) were performed, starting from the crystallographic positions of all heavy atoms in the crystals. By employing the particle-mesh-Ewald algorithm [Darden et al., J. Chem. Phys. 98 (1993) 10089] to accommodate the long-range Coulomb interactions, highly accurate MD structures were obtained for both crystals. The instantaneous root-mean-square positional deviations of the heavy atoms equilibrate at approximately 0.4 Å for both systems, while the experimental and calculated temperature factors are comparable in size. These results describe the first successful crystal MD simulation of RNA molecules.

  2. In pursuit of an accurate spatial and temporal model of biomolecules at the atomistic level: a perspective on computer simulation

    PubMed Central

    Gray, Alan; Harlen, Oliver G.; Harris, Sarah A.; Khalid, Syma; Leung, Yuk Ming; Lonsdale, Richard; Mulholland, Adrian J.; Pearson, Arwen R.; Read, Daniel J.; Richardson, Robin A.

    2015-01-01

    Despite huge advances in the computational techniques available for simulating biomolecules at the quantum-mechanical, atomistic and coarse-grained levels, there is still a widespread perception amongst the experimental community that these calculations are highly specialist and are not generally applicable by researchers outside the theoretical community. In this article, the successes and limitations of biomolecular simulation and the further developments that are likely in the near future are discussed. A brief overview is also provided of the experimental biophysical methods that are commonly used to probe biomolecular structure and dynamics, and the accuracy of the information that can be obtained from each is compared with that from modelling. It is concluded that progress towards an accurate spatial and temporal model of biomacromolecules requires a combination of all of these biophysical techniques, both experimental and computational. PMID:25615870

  3. Physical resist models and their calibration: their readiness for accurate EUV lithography simulation

    NASA Astrophysics Data System (ADS)

    Klostermann, U. K.; Mülders, T.; Schmöller, T.; Lorusso, G. F.; Hendrickx, E.

    2010-04-01

    In this paper, we discuss the performance of EUV resist models in terms of predictive accuracy, and we assess the readiness of the corresponding model calibration methodology. The study is done on an extensive OPC data set collected at IMEC for the ShinEtsu resist SEVR-59 on the ASML EUV Alpha Demo Tool (ADT), with the data set including more than thousand CD values. We address practical aspects such as the speed of calibration and selection of calibration patterns. The model is calibrated on 12 process window data series varying in pattern width (32, 36, 40 nm), orientation (H, V) and pitch (dense, isolated). The minimum measured feature size at nominal process condition is a 32 nm CD at a dense pitch of 64 nm. Mask metrology is applied to verify and eventually correct nominal width of the drawn CD. Cross-sectional SEM information is included in the calibration to tune the simulated resist loss and sidewall angle. The achieved calibration RMS is ~ 1.0 nm. We show what elements are important to obtain a well calibrated model. We discuss the impact of 3D mask effects on the Bossung tilt. We demonstrate that a correct representation of the flare level during the calibration is important to achieve a high predictability at various flare conditions. Although the model calibration is performed on a limited subset of the measurement data (one dimensional structures only), its accuracy is validated based on a large number of OPC patterns (at nominal dose and focus conditions) not included in the calibration; validation RMS results as small as 1 nm can be reached. Furthermore, we study the model's extendibility to two-dimensional end of line (EOL) structures. Finally, we correlate the experimentally observed fingerprint of the CD uniformity to a model, where EUV tool specific signatures are taken into account.

  4. Voxel-based registration of simulated and real patient CBCT data for accurate dental implant pose estimation

    NASA Astrophysics Data System (ADS)

    Moreira, António H. J.; Queirós, Sandro; Morais, Pedro; Rodrigues, Nuno F.; Correia, André Ricardo; Fernandes, Valter; Pinho, A. C. M.; Fonseca, Jaime C.; Vilaça, João. L.

    2015-03-01

    The success of dental implant-supported prosthesis is directly linked to the accuracy obtained during implant's pose estimation (position and orientation). Although traditional impression techniques and recent digital acquisition methods are acceptably accurate, a simultaneously fast, accurate and operator-independent methodology is still lacking. Hereto, an image-based framework is proposed to estimate the patient-specific implant's pose using cone-beam computed tomography (CBCT) and prior knowledge of implanted model. The pose estimation is accomplished in a threestep approach: (1) a region-of-interest is extracted from the CBCT data using 2 operator-defined points at the implant's main axis; (2) a simulated CBCT volume of the known implanted model is generated through Feldkamp-Davis-Kress reconstruction and coarsely aligned to the defined axis; and (3) a voxel-based rigid registration is performed to optimally align both patient and simulated CBCT data, extracting the implant's pose from the optimal transformation. Three experiments were performed to evaluate the framework: (1) an in silico study using 48 implants distributed through 12 tridimensional synthetic mandibular models; (2) an in vitro study using an artificial mandible with 2 dental implants acquired with an i-CAT system; and (3) two clinical case studies. The results shown positional errors of 67+/-34μm and 108μm, and angular misfits of 0.15+/-0.08° and 1.4°, for experiment 1 and 2, respectively. Moreover, in experiment 3, visual assessment of clinical data results shown a coherent alignment of the reference implant. Overall, a novel image-based framework for implants' pose estimation from CBCT data was proposed, showing accurate results in agreement with dental prosthesis modelling requirements.

  5. Accurate Monte Carlo simulations for nozzle design, commissioning and quality assurance for a proton radiation therapy facility.

    PubMed

    Paganetti, H; Jiang, H; Lee, S Y; Kooy, H M

    2004-07-01

    Monte Carlo dosimetry calculations are essential methods in radiation therapy. To take full advantage of this tool, the beam delivery system has to be simulated in detail and the initial beam parameters have to be known accurately. The modeling of the beam delivery system itself opens various areas where Monte Carlo calculations prove extremely helpful, such as for design and commissioning of a therapy facility as well as for quality assurance verification. The gantry treatment nozzles at the Northeast Proton Therapy Center (NPTC) at Massachusetts General Hospital (MGH) were modeled in detail using the GEANT4.5.2 Monte Carlo code. For this purpose, various novel solutions for simulating irregular shaped objects in the beam path, like contoured scatterers, patient apertures or patient compensators, were found. The four-dimensional, in time and space, simulation of moving parts, such as the modulator wheel, was implemented. Further, the appropriate physics models and cross sections for proton therapy applications were defined. We present comparisons between measured data and simulations. These show that by modeling the treatment nozzle with millimeter accuracy, it is possible to reproduce measured dose distributions with an accuracy in range and modulation width, in the case of a spread-out Bragg peak (SOBP), of better than 1 mm. The excellent agreement demonstrates that the simulations can even be used to generate beam data for commissioning treatment planning systems. The Monte Carlo nozzle model was used to study mechanical optimization in terms of scattered radiation and secondary radiation in the design of the nozzles. We present simulations on the neutron background. Further, the Monte Carlo calculations supported commissioning efforts in understanding the sensitivity of beam characteristics and how these influence the dose delivered. We present the sensitivity of dose distributions in water with respect to various beam parameters and geometrical misalignments

  6. Modeling and simulating the bidirectional reflectance distribution function (BRDF) of seawater covered by oil slicks

    NASA Astrophysics Data System (ADS)

    Ren, Zijian; Ma, Chunyong; Chen, Lu; Chen, Ge

    2016-05-01

    A high-efficiency anisotropic model for bidirectional reflectance distribution function (BRDF) of seawater covered by oil slicks (SWCOS) was proposed. This model was set by combining a BRDF model for anisotropic rough sea surface whose slopes follow Gaussian distribution and the two-beam inference theory of a thin film. We have simulated the BRDFs of oil slicks by using the above model and the measured complex refractive index data of Romashkino crude oil. In addition, the relationships between the BRDF of oil slicks and the wind speed of sea surface, thickness of oil slick, complex refractive index of crude oil and the incident zenith angle were analyzed. Also, the differences between optical characteristics of clean water and of polluted water were discussed in the context of the optical contrast of SWCOS. With high simulation speed and reliable simulation precision, this model provides a theoretical basis for rapid detection of oil spill.

  7. Accurate electrical prediction of memory array through SEM-based edge-contour extraction using SPICE simulation

    NASA Astrophysics Data System (ADS)

    Shauly, Eitan; Rotstein, Israel; Peltinov, Ram; Latinski, Sergei; Adan, Ofer; Levi, Shimon; Menadeva, Ovadya

    2009-03-01

    The continues transistors scaling efforts, for smaller devices, similar (or larger) drive current/um and faster devices, increase the challenge to predict and to control the transistor off-state current. Typically, electrical simulators like SPICE, are using the design intent (as-drawn GDS data). At more sophisticated cases, the simulators are fed with the pattern after lithography and etch process simulations. As the importance of electrical simulation accuracy is increasing and leakage is becoming more dominant, there is a need to feed these simulators, with more accurate information extracted from physical on-silicon transistors. Our methodology to predict changes in device performances due to systematic lithography and etch effects was used in this paper. In general, the methodology consists on using the OPCCmaxTM for systematic Edge-Contour-Extraction (ECE) from transistors, taking along the manufacturing and includes any image distortions like line-end shortening, corner rounding and line-edge roughness. These measurements are used for SPICE modeling. Possible application of this new metrology is to provide a-head of time, physical and electrical statistical data improving time to market. In this work, we applied our methodology to analyze a small and large array's of 2.14um2 6T-SRAM, manufactured using Tower Standard Logic for General Purposes Platform. 4 out of the 6 transistors used "U-Shape AA", known to have higher variability. The predicted electrical performances of the transistors drive current and leakage current, in terms of nominal values and variability are presented. We also used the methodology to analyze an entire SRAM Block array. Study of an isolation leakage and variability are presented.

  8. Dissipative particle dynamics simulation on the rheological properties of heavy crude oil

    NASA Astrophysics Data System (ADS)

    Wang, Sibo; Xu, Junbo; Wen, Hao

    2015-11-01

    The rheological properties of heavy crude oil have a significant impact on the production, refining and transportation. In this paper, dissipative particle dynamics (DPD) simulations were performed to study the effects of the addition of light crude oil and emulsification on the rheological properties of heavy crude oil. The simulation results reflected that the addition of light crude oil reduced the viscosity effectively. The shear thinning behaviour of crude oil mixtures were becoming less distinct as the increase of the mass fraction of light crude oil. According to the statistics, the shear had an influence on the aggregation and spatial orientation of asphaltene molecules. In addition, the relationship between the viscosity and the oil mass fraction was investigated in the simulations of emulsion systems. The viscosity increased with the oil mass fraction slowly in oil-in-water emulsions. When the oil mass fraction was higher than 50%, the increase became much faster since systems had been converted into water-in-oil emulsions. The equilibrated morphologies of emulsion systems were shown to illustrate the phase inversion. The surfactant-like feature of asphaltenes was also studied in the simulations.

  9. Modelling the Constraints of Spatial Environment in Fauna Movement Simulations: Comparison of a Boundaries Accurate Function and a Cost Function

    NASA Astrophysics Data System (ADS)

    Jolivet, L.; Cohen, M.; Ruas, A.

    2015-08-01

    Landscape influences fauna movement at different levels, from habitat selection to choices of movements' direction. Our goal is to provide a development frame in order to test simulation functions for animal's movement. We describe our approach for such simulations and we compare two types of functions to calculate trajectories. To do so, we first modelled the role of landscape elements to differentiate between elements that facilitate movements and the ones being hindrances. Different influences are identified depending on landscape elements and on animal species. Knowledge were gathered from ecologists, literature and observation datasets. Second, we analysed the description of animal movement recorded with GPS at fine scale, corresponding to high temporal frequency and good location accuracy. Analysing this type of data provides information on the relation between landscape features and movements. We implemented an agent-based simulation approach to calculate potential trajectories constrained by the spatial environment and individual's behaviour. We tested two functions that consider space differently: one function takes into account the geometry and the types of landscape elements and one cost function sums up the spatial surroundings of an individual. Results highlight the fact that the cost function exaggerates the distances travelled by an individual and simplifies movement patterns. The geometry accurate function represents a good bottom-up approach for discovering interesting areas or obstacles for movements.

  10. In pursuit of an accurate spatial and temporal model of biomolecules at the atomistic level: a perspective on computer simulation

    SciTech Connect

    Gray, Alan; Harlen, Oliver G.; Harris, Sarah A.; Khalid, Syma; Leung, Yuk Ming; Lonsdale, Richard; Mulholland, Adrian J.; Pearson, Arwen R.; Read, Daniel J.; Richardson, Robin A.

    2015-01-01

    The current computational techniques available for biomolecular simulation are described, and the successes and limitations of each with reference to the experimental biophysical methods that they complement are presented. Despite huge advances in the computational techniques available for simulating biomolecules at the quantum-mechanical, atomistic and coarse-grained levels, there is still a widespread perception amongst the experimental community that these calculations are highly specialist and are not generally applicable by researchers outside the theoretical community. In this article, the successes and limitations of biomolecular simulation and the further developments that are likely in the near future are discussed. A brief overview is also provided of the experimental biophysical methods that are commonly used to probe biomolecular structure and dynamics, and the accuracy of the information that can be obtained from each is compared with that from modelling. It is concluded that progress towards an accurate spatial and temporal model of biomacromolecules requires a combination of all of these biophysical techniques, both experimental and computational.

  11. Simulating the Cranfield geological carbon sequestration project with high-resolution static models and an accurate equation of state

    DOE PAGES

    Soltanian, Mohamad Reza; Amooie, Mohammad Amin; Cole, David R.; Graham, David E.; Hosseini, Seyyed Abolfazl; Hovorka, Susan; Pfiffner, Susan M.; Phelps, Tommy Joe; Moortgat, Joachim

    2016-10-11

    In this study, a field-scale carbon dioxide (CO2) injection pilot project was conducted as part of the Southeast Regional Sequestration Partnership (SECARB) at Cranfield, Mississippi. We present higher-order finite element simulations of the compositional two-phase CO2-brine flow and transport during the experiment. High- resolution static models of the formation geology in the Detailed Area Study (DAS) located below the oil- water contact (brine saturated) are used to capture the impact of connected flow paths on breakthrough times in two observation wells. Phase behavior is described by the cubic-plus-association (CPA) equation of state, which takes into account the polar nature ofmore » water molecules. Parameter studies are performed to investigate the importance of Fickian diffusion, permeability heterogeneity, relative permeabilities, and capillarity. Simulation results for the pressure response in the injection well and the CO2 breakthrough times at the observation wells show good agreement with the field data. For the high injection rates and short duration of the experiment, diffusion is relatively unimportant (high P clet numbers), while relative permeabilities have a profound impact on the pressure response. High-permeability pathways, created by fluvial deposits, strongly affect the CO2 transport and highlight the importance of properly characterizing the formation heterogeneity in future carbon sequestration projects.« less

  12. A specific PFT and sub-canopy structure for simulating oil palm in the Community Land Model

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Knohl, A.; Roupsard, O.; Bernoux, M.; LE Maire, G.; Panferov, O.; Kotowska, M.; Meijide, A.

    2015-12-01

    Towards an effort to quantify the effects of rainforests to oil palm conversion on land-atmosphere carbon, water and energy fluxes, a specific plant functional type (PFT) and sub-canopy structure are developed for simulating oil palm within the Community Land Model (CLM4.5). Current global land surface models only simulate annual crops beside natural vegetation. In this study, a multilayer oil palm subroutine is developed in CLM4.5 for simulating oil palm's phenology and carbon and nitrogen allocation. The oil palm has monopodial morphology and sequential phenology of around 40 stacked phytomers, each carrying a large leaf and a fruit bunch, forming a natural multilayer canopy. A sub-canopy phenological and physiological parameterization is thus introduced, so that multiple phytomer components develop simultaneously but according to their different phenological steps (growth, yield and senescence) at different canopy layers. This specific multilayer structure was proved useful for simulating canopy development in terms of leaf area index (LAI) and fruit yield in terms of carbon and nitrogen outputs in Jambi, Sumatra (Fan et al. 2015). The study supports that species-specific traits, such as palm's monopodial morphology and sequential phenology, are necessary representations in terrestrial biosphere models in order to accurately simulate vegetation dynamics and feedbacks to climate. Further, oil palm's multilayer structure allows adding all canopy-level calculations of radiation, photosynthesis, stomatal conductance and respiration, beside phenology, also to the sub-canopy level, so as to eliminate scale mismatch problem among different processes. A series of adaptations are made to the CLM model. Initial results show that the adapted multilayer radiative transfer scheme and the explicit represention of oil palm's canopy structure improve on simulating photosynthesis-light response curve. The explicit photosynthesis and dynamic leaf nitrogen calculations per canopy

  13. Logrithmic current simulator generates electrical currents accurately between 10 to the minus 11 ampere to 10 to the minus 3 ampere

    NASA Technical Reports Server (NTRS)

    Wilson, J.

    1966-01-01

    Current generator accurately simulates electric currents in the range of 10 to the minus 11th power to 0.001 ampere. Compensation networks have been devised to improve the accuracy at the lower current levels.

  14. Mathematical analysis and algorithms for efficiently and accurately implementing stochastic simulations of short-term synaptic depression and facilitation.

    PubMed

    McDonnell, Mark D; Mohan, Ashutosh; Stricker, Christian

    2013-01-01

    The release of neurotransmitter vesicles after arrival of a pre-synaptic action potential (AP) at cortical synapses is known to be a stochastic process, as is the availability of vesicles for release. These processes are known to also depend on the recent history of AP arrivals, and this can be described in terms of time-varying probabilities of vesicle release. Mathematical models of such synaptic dynamics frequently are based only on the mean number of vesicles released by each pre-synaptic AP, since if it is assumed there are sufficiently many vesicle sites, then variance is small. However, it has been shown recently that variance across sites can be significant for neuron and network dynamics, and this suggests the potential importance of studying short-term plasticity using simulations that do generate trial-to-trial variability. Therefore, in this paper we study several well-known conceptual models for stochastic availability and release. We state explicitly the random variables that these models describe and propose efficient algorithms for accurately implementing stochastic simulations of these random variables in software or hardware. Our results are complemented by mathematical analysis and statement of pseudo-code algorithms.

  15. DISPERSANT EFFECTIVENESS ON THREE OILS UNDER VARIOUS SIMULATED ENVIRONMENTAL CONDITIONS

    EPA Science Inventory

    The complexity of chemical and physical interactions between spilled oils, dispersants and the sea, necessitates an empirical approach for describing the interaction between the dispersant and oil slick which may provide a guide to dispersant effects on oil slicks. Recently, US ...

  16. An accurate classical simulation of a two-dimensional vibrational spectrum: OD stretch spectrum of a hydrated HOD molecule.

    PubMed

    Jeon, Jonggu; Cho, Minhaeng

    2014-07-17

    An accurate computational method for the classical simulation of the two-dimensional vibrational spectra is presented. The method refines our previous computational method for the third order vibrational response function in the classical limit, and it enables capturing the diagonal elongation and its waiting time (T) dependence widely observed in experimental two-dimensional infrared (2D IR) spectra of intramolecular modes. The improvement is achieved by a series of new developments including (i) a block algorithm for the stability matrix computation, (ii) new equations of motion for the position-perturbed molecular dynamics (MD) trajectory, and (iii) enhanced sampling efficiency by exploiting the time-reversal invariance of MD trajectories. The method is applied to the simulation of 2D IR spectra of the OD stretch mode in a hydrated HOD molecule, employing a hybrid quantum mechanical/molecular mechanical force field. The simulated spectra exhibit diagonal elongation of the 2D IR signal at small T, reflecting the correlation of individual transitions among the inhomogeneously broadened ensemble. The slopes of the nodal lines of the elongated signals are found to decay with a time scale of 1.6 ps as T increases, in reasonable agreement with the frequency correlation decay time of 1.2 ps. The amplitudes of the positive and negative peaks also decay as T increases, due to vibrational population relaxation and molecular rotation. The peak positions tend to blue shift with increasing T, reflecting the different relaxation rates of the strongly and weakly solvated HOD species. These results indicate that the present method can reliably predict the waiting-time-dependent changes of 2D IR spectra of a single vibrational chromophore in solution. PMID:24601590

  17. Multigrid Methods for Fully Implicit Oil Reservoir Simulation

    NASA Technical Reports Server (NTRS)

    Molenaar, J.

    1996-01-01

    In this paper we consider the simultaneous flow of oil and water in reservoir rock. This displacement process is modeled by two basic equations: the material balance or continuity equations and the equation of motion (Darcy's law). For the numerical solution of this system of nonlinear partial differential equations there are two approaches: the fully implicit or simultaneous solution method and the sequential solution method. In the sequential solution method the system of partial differential equations is manipulated to give an elliptic pressure equation and a hyperbolic (or parabolic) saturation equation. In the IMPES approach the pressure equation is first solved, using values for the saturation from the previous time level. Next the saturations are updated by some explicit time stepping method; this implies that the method is only conditionally stable. For the numerical solution of the linear, elliptic pressure equation multigrid methods have become an accepted technique. On the other hand, the fully implicit method is unconditionally stable, but it has the disadvantage that in every time step a large system of nonlinear algebraic equations has to be solved. The most time-consuming part of any fully implicit reservoir simulator is the solution of this large system of equations. Usually this is done by Newton's method. The resulting systems of linear equations are then either solved by a direct method or by some conjugate gradient type method. In this paper we consider the possibility of applying multigrid methods for the iterative solution of the systems of nonlinear equations. There are two ways of using multigrid for this job: either we use a nonlinear multigrid method or we use a linear multigrid method to deal with the linear systems that arise in Newton's method. So far only a few authors have reported on the use of multigrid methods for fully implicit simulations. Two-level FAS algorithm is presented for the black-oil equations, and linear multigrid for

  18. Reactive plasma upgrade of squalane - a heavy oil simulant

    SciTech Connect

    Kong, P.C.; Watkins, A.D.; Detering, B.A.; Thomas, C.P.

    1995-10-01

    U.S. light crude oil production has steadily declined over the last two decades. However, huge known heavy oil deposits in the North American continent remain largely untapped. In the past 10 years, the API gravity of crude oils has been decreasing by about 0.17% per year, and the sulfur content has been increasing by about 0.027% per year. As the API gravity of crude oil decreases, there will be an urgent need for economically viable new technologies to upgrade the heavy oil to a high API gravity feed stock for the refineries. The Idaho National Engineering Laboratory is investigating an innovative plasma process to upgrade heavy oil and refinery residuum. This paper will present some of the results and the implications of this technology for heavy oil upgrade and conversion.

  19. Accurate path integral molecular dynamics simulation of ab-initio water at near-zero added cost

    NASA Astrophysics Data System (ADS)

    Elton, Daniel; Fritz, Michelle; Soler, José; Fernandez-Serra, Marivi

    It is now established that nuclear quantum motion plays an important role in determining water's structure and dynamics. These effects are important to consider when evaluating DFT functionals and attempting to develop better ones for water. The standard way of treating nuclear quantum effects, path integral molecular dynamics (PIMD), multiplies the number of energy/force calculations by the number of beads, which is typically 32. Here we introduce a method whereby PIMD can be incorporated into a DFT molecular dynamics simulation at virtually zero cost. The method is based on the cluster (many body) expansion of the energy. We first subtract the DFT monomer energies, using a custom DFT-based monomer potential energy surface. The evolution of the PIMD beads is then performed using only the more-accurate Partridge-Schwenke monomer energy surface. The DFT calculations are done using the centroid positions. Various bead thermostats can be employed to speed up the sampling of the quantum ensemble. The method bears some resemblance to multiple timestep algorithms and other schemes used to speed up PIMD with classical force fields. We show that our method correctly captures some of key effects of nuclear quantum motion on both the structure and dynamics of water. We acknowledge support from DOE Award No. DE-FG02-09ER16052 (D.E.) and DOE Early Career Award No. DE-SC0003871 (M.V.F.S.).

  20. Time-Accurate Unsteady Flow Simulations Supporting the SRM T+68-Second Pressure Spike Anomaly Investigation (STS-54B)

    NASA Technical Reports Server (NTRS)

    Dougherty, N. S.; Burnette, D. W.; Holt, J. B.; Matienzo, Jose

    1993-01-01

    Time-accurate unsteady flow simulations are being performed supporting the SRM T+68sec pressure 'spike' anomaly investigation. The anomaly occurred in the RH SRM during the STS-54 flight (STS-54B) but not in the LH SRM (STS-54A) causing a momentary thrust mismatch approaching the allowable limit at that time into the flight. Full-motor internal flow simulations using the USA-2D axisymmetric code are in progress for the nominal propellant burn-back geometry and flow conditions at T+68-sec--Pc = 630 psi, gamma = 1.1381, T(sub c) = 6200 R, perfect gas without aluminum particulate. In a cooperative effort with other investigation team members, CFD-derived pressure loading on the NBR and castable inhibitors was used iteratively to obtain nominal deformed geometry of each inhibitor, and the deformed (bent back) inhibitor geometry was entered into this model. Deformed geometry was computed using structural finite-element models. A solution for the unsteady flow has been obtained for the nominal flow conditions (existing prior to the occurrence of the anomaly) showing sustained standing pressure oscillations at nominally 14.5 Hz in the motor IL acoustic mode that flight and static test data confirm to be normally present at this time. Average mass flow discharged from the nozzle was confirmed to be the nominal expected (9550 lbm/sec). The local inlet boundary condition is being perturbed at the location of the presumed reconstructed anomaly as identified by interior ballistics performance specialist team members. A time variation in local mass flow is used to simulate sudden increase in burning area due to localized propellant grain cracks. The solution will proceed to develop a pressure rise (proportional to total mass flow rate change squared). The volume-filling time constant (equivalent to 0.5 Hz) comes into play in shaping the rise rate of the developing pressure 'spike' as it propagates at the speed of sound in both directions to the motor head end and nozzle. The

  1. IT - OSRA: applying ensemble simulations to estimate the oil spill hazard associated to operational and accidental oil spills

    NASA Astrophysics Data System (ADS)

    Sepp Neves, Antonio Augusto; Pinardi, Nadia; martins, Flavio

    2016-04-01

    Every year, 270,000 tonnes of oil are estimated to be spilled in the ocean by vessel operations (e.g. tank washing, leakage of lubricants) and the so called operational spills are typically associated with small volumes and high occurrence rate. Vessel-related accidental spills (e.g. collisions, explosions) seldom occur and usually involve high volumes of oil, accounting for about 100,000 tonnes/year. The occurrence of accidental spills and their impacts have been well documented in the available literature. On the other hand, occurrence rates of operational spills and the effects they have on the marine and coastal environments remain very uncertain due to insufficient sampling effort and methodological limitations. Trying to foresee when and where an oil spill will occur in a certain area, its characteristics and impacts is, at present, impossible. Oil spill risk assessments (OSRAs) have been employed in several parts of the globe in order to deal with such uncertainties and protect the marine environment. In the present work, we computed the oil spill risk applying ensemble oil spill simulations following an ISO-31000 compliant OSRA methodology (Sepp Neves et al. , 2015). The ensemble experiment was carried out for the Algarve coast (southern Portugal) generating a unique data set of 51,200 numerical oil spill simulations covering the main sources of uncertainties (i.e. where and when the spill will happen and oil spill model configuration). From the generated data set, the risk due to accidental and operational spills was mapped for the Algarve municipalities based on the frequency and magnitude (i.e. concentrations) of beaching events and the main sources of risk were identified. The socioeconomic and environmental dimensions of the risk were treated separately. Seasonal changes in the risk index proposed due to the variability of meteo-oceanographic variables (i.e. currents and waves) were also quantified.

  2. A scalable parallel black oil simulator on distributed memory parallel computers

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Liu, Hui; Chen, Zhangxin

    2015-11-01

    This paper presents our work on developing a parallel black oil simulator for distributed memory computers based on our in-house parallel platform. The parallel simulator is designed to overcome the performance issues of common simulators that are implemented for personal computers and workstations. The finite difference method is applied to discretize the black oil model. In addition, some advanced techniques are employed to strengthen the robustness and parallel scalability of the simulator, including an inexact Newton method, matrix decoupling methods, and algebraic multigrid methods. A new multi-stage preconditioner is proposed to accelerate the solution of linear systems from the Newton methods. Numerical experiments show that our simulator is scalable and efficient, and is capable of simulating extremely large-scale black oil problems with tens of millions of grid blocks using thousands of MPI processes on parallel computers.

  3. Models, Simulators, and Data-driven Resources for Oil and Natural Gas Research

    DOE Data Explorer

    NETL provides a number of analytical tools to assist in conducting oil and natural gas research. Software, developed under various DOE/NETL projects, includes numerical simulators, analytical models, databases, and documentation.[copied from http://www.netl.doe.gov/technologies/oil-gas/Software/Software_main.html] Links lead users to methane hydrates models, preedictive models, simulators, databases, and other software tools or resources.

  4. Towards an accurate representation of electrostatics in classical force fields: Efficient implementation of multipolar interactions in biomolecular simulations

    NASA Astrophysics Data System (ADS)

    Sagui, Celeste; Pedersen, Lee G.; Darden, Thomas A.

    2004-01-01

    The accurate simulation of biologically active macromolecules faces serious limitations that originate in the treatment of electrostatics in the empirical force fields. The current use of "partial charges" is a significant source of errors, since these vary widely with different conformations. By contrast, the molecular electrostatic potential (MEP) obtained through the use of a distributed multipole moment description, has been shown to converge to the quantum MEP outside the van der Waals surface, when higher order multipoles are used. However, in spite of the considerable improvement to the representation of the electronic cloud, higher order multipoles are not part of current classical biomolecular force fields due to the excessive computational cost. In this paper we present an efficient formalism for the treatment of higher order multipoles in Cartesian tensor formalism. The Ewald "direct sum" is evaluated through a McMurchie-Davidson formalism [L. McMurchie and E. Davidson, J. Comput. Phys. 26, 218 (1978)]. The "reciprocal sum" has been implemented in three different ways: using an Ewald scheme, a particle mesh Ewald (PME) method, and a multigrid-based approach. We find that even though the use of the McMurchie-Davidson formalism considerably reduces the cost of the calculation with respect to the standard matrix implementation of multipole interactions, the calculation in direct space remains expensive. When most of the calculation is moved to reciprocal space via the PME method, the cost of a calculation where all multipolar interactions (up to hexadecapole-hexadecapole) are included is only about 8.5 times more expensive than a regular AMBER 7 [D. A. Pearlman et al., Comput. Phys. Commun. 91, 1 (1995)] implementation with only charge-charge interactions. The multigrid implementation is slower but shows very promising results for parallelization. It provides a natural way to interface with continuous, Gaussian-based electrostatics in the future. It is

  5. Towards an accurate representation of electrostatics in classical force fields: efficient implementation of multipolar interactions in biomolecular simulations.

    PubMed

    Sagui, Celeste; Pedersen, Lee G; Darden, Thomas A

    2004-01-01

    The accurate simulation of biologically active macromolecules faces serious limitations that originate in the treatment of electrostatics in the empirical force fields. The current use of "partial charges" is a significant source of errors, since these vary widely with different conformations. By contrast, the molecular electrostatic potential (MEP) obtained through the use of a distributed multipole moment description, has been shown to converge to the quantum MEP outside the van der Waals surface, when higher order multipoles are used. However, in spite of the considerable improvement to the representation of the electronic cloud, higher order multipoles are not part of current classical biomolecular force fields due to the excessive computational cost. In this paper we present an efficient formalism for the treatment of higher order multipoles in Cartesian tensor formalism. The Ewald "direct sum" is evaluated through a McMurchie-Davidson formalism [L. McMurchie and E. Davidson, J. Comput. Phys. 26, 218 (1978)]. The "reciprocal sum" has been implemented in three different ways: using an Ewald scheme, a particle mesh Ewald (PME) method, and a multigrid-based approach. We find that even though the use of the McMurchie-Davidson formalism considerably reduces the cost of the calculation with respect to the standard matrix implementation of multipole interactions, the calculation in direct space remains expensive. When most of the calculation is moved to reciprocal space via the PME method, the cost of a calculation where all multipolar interactions (up to hexadecapole-hexadecapole) are included is only about 8.5 times more expensive than a regular AMBER 7 [D. A. Pearlman et al., Comput. Phys. Commun. 91, 1 (1995)] implementation with only charge-charge interactions. The multigrid implementation is slower but shows very promising results for parallelization. It provides a natural way to interface with continuous, Gaussian-based electrostatics in the future. It is

  6. A streamline splitting pore-network approach for computationally inexpensive and accurate simulation of transport in porous media

    SciTech Connect

    Mehmani, Yashar; Oostrom, Martinus; Balhoff, Matthew

    2014-03-20

    Several approaches have been developed in the literature for solving flow and transport at the pore-scale. Some authors use a direct modeling approach where the fundamental flow and transport equations are solved on the actual pore-space geometry. Such direct modeling, while very accurate, comes at a great computational cost. Network models are computationally more efficient because the pore-space morphology is approximated. Typically, a mixed cell method (MCM) is employed for solving the flow and transport system which assumes pore-level perfect mixing. This assumption is invalid at moderate to high Peclet regimes. In this work, a novel Eulerian perspective on modeling flow and transport at the pore-scale is developed. The new streamline splitting method (SSM) allows for circumventing the pore-level perfect mixing assumption, while maintaining the computational efficiency of pore-network models. SSM was verified with direct simulations and excellent matches were obtained against micromodel experiments across a wide range of pore-structure and fluid-flow parameters. The increase in the computational cost from MCM to SSM is shown to be minimal, while the accuracy of SSM is much higher than that of MCM and comparable to direct modeling approaches. Therefore, SSM can be regarded as an appropriate balance between incorporating detailed physics and controlling computational cost. The truly predictive capability of the model allows for the study of pore-level interactions of fluid flow and transport in different porous materials. In this paper, we apply SSM and MCM to study the effects of pore-level mixing on transverse dispersion in 3D disordered granular media.

  7. Development of a compositional model fully coupled with geomechanics and its application to tight oil reservoir simulation

    NASA Astrophysics Data System (ADS)

    Xiong, Yi

    solutions and results of a commercial simulator before conducting numerical studies. The numerical studies demonstrate the effect of capillary pressure on VLE, and further on production performance. The significant effect of capillary pressure on VLE leads to the suppression of bubble-point pressure and more light components dissolved in the oil phase. Consequently it is observed that there is smaller gas saturation, larger mole fractions of light components, and faster pressure decreasing at reservoir conditions; meanwhile less gas and more oil are produced at surface. The substantial decrease in reservoir pore pressure results in a large increase of effective stress, which induces the changes of rock properties and influences the production performance. The stress-induced degradation of permeability undermines the production performance, and the geomechanical effect on the permeability of natural fractures is mainly responsible for the undermined production performance. The reduction of pore size due to the geomechanical effect could increase the capillary pressure, which enlarges the influence of capillarity on VLE and further suppresses bubble-point pressure. On the other hand, the effect of capillary pressure on VLE influences the fluid flow and therefore influences the effective stress through the flow-stress coupling process. Thus the interaction between pore confinement and rock compaction can be modeled with MSFLOW_COM, and illustrated through numerical studies. This research provides a three-dimensional numerical tool for accurately modeling porous and fractured tight oil reservoirs. The developed simulator is able to assist scientists and engineers to study and understand the complex multiphase, multi-component fluid flow behaviors in tight oil reservoirs.

  8. Accurate Analysis and Evaluation of Acidic Plant Growth Regulators in Transgenic and Nontransgenic Edible Oils with Facile Microwave-Assisted Extraction-Derivatization.

    PubMed

    Liu, Mengge; Chen, Guang; Guo, Hailong; Fan, Baolei; Liu, Jianjun; Fu, Qiang; Li, Xiu; Lu, Xiaomin; Zhao, Xianen; Li, Guoliang; Sun, Zhiwei; Xia, Lian; Zhu, Shuyun; Yang, Daoshan; Cao, Ziping; Wang, Hua; Suo, Yourui; You, Jinmao

    2015-09-16

    Determination of plant growth regulators (PGRs) in a signal transduction system (STS) is significant for transgenic food safety, but may be challenged by poor accuracy and analyte instability. In this work, a microwave-assisted extraction-derivatization (MAED) method is developed for six acidic PGRs in oil samples, allowing an efficient (<1.5 h) and facile (one step) pretreatment. Accuracies are greatly improved, particularly for gibberellin A3 (-2.72 to -0.65%) as compared with those reported (-22 to -2%). Excellent selectivity and quite low detection limits (0.37-1.36 ng mL(-1)) are enabled by fluorescence detection-mass spectrum monitoring. Results show the significant differences in acidic PGRs between transgenic and nontransgenic oils, particularly 1-naphthaleneacetic acid (1-NAA), implying the PGRs induced variations of components and genes. This study provides, for the first time, an accurate and efficient determination for labile PGRs involved in STS and a promising concept for objectively evaluating the safety of transgenic foods.

  9. Simulation analysis of the oil/water structure in the downhole with presence of hydrocyclone separator

    NASA Astrophysics Data System (ADS)

    Jamil, I. E.; Al-Kayiem, H. H.

    2015-12-01

    The maturing oil fields with increasing water production can pose a challenge in terms of produced water handling and disposal issues. This paper presents the modelling and simulation procedure of the two-phase flow of water/oil in a downhole using ANSYS- FLUENT 14 software. The developed procedure successfully simulated the production zone and the interaction of the two fluids in a natural environment where the reservoir pressure is the sole driving force. The results show significant difference of volume distribution in the flows with different oil content. The model can become an essential tool to assist in prediction of the behavior of oil/water mixture flow in the wellbores, and to serve in designing downhole oil/water separators.

  10. [Treatment of simulated produced wastewater from polymer flooding in oil production using dithiocarbamate-type flocculant].

    PubMed

    Gao, Yue; Jia, Yu-Yan; Gao, Bao-Yu; Cao, Bai-Chuan; Zhang, Yong-Qiang; Lu, Lei

    2010-10-01

    A dithiocarbamate flocculant, DTC (T403), was prepared by the reaction of amine-terminated polyoxypropane-ether compound known as Jeffamine-T403 and carbon disulfide in alkaline solution. The oil removal efficiency of DTC (T403) for simulated produced wastewater from polymer flooding in oil production was studied by Jar-test. The effect of the dosage of DTC (T403), hydrolyzed polyacrylamide (HPAM), Fe2+ and Fe3+ ions, and pH on the oil removal efficiency of DTC (T403) was investigated. The results showed that the chelate polymer formed by DTC (T403) and Fe2+ ion has good oil removal performance by net capturing mechanism. HPAM had a negative effect on oil removal efficiency of DTC (T403). For the treatment of the simulated wastewater containing 0-900 mg/L of HPAM and 300 mg/L of oil, the residual oil concentrations in water samples decreased below 10 mg/L when the dosage of Fe2+ and DTC (T403) was 10 mg/L and 25 mg/L, respectively. The oil removal efficiency of DTC (T403) was affected by pH and good oil removal efficiency was obtained when the pH was below 7.5. DTC (T403) is appropriate for the treatment of oily wastewater containing Fe2+ ion.

  11. Oil spills and AI: How to manage resources through simulation

    SciTech Connect

    Giribone, P.; Bruzzone, A.G.; Caddeo, S.

    1995-12-31

    Today, in the Mediterranean theater of the Upper Tyrrhenian, the ecological risk involving oil installations is still quite high. This is due to the fact that valuable environmental and tourist areas exist together with large industrial and port structures; in particular, recent events have demonstrated the danger involving oil spills along the Ligurian coastline. This study proposes an approach to plan the operations that should be performed when accidents occur, based on the use of AI techniques.

  12. Underwater Oil Plume Intrusion from Deepwater Blowouts - A Large-Eddy Simulation Study

    NASA Astrophysics Data System (ADS)

    Yang, D.; Chen, B.; Chamecki, M.; Meneveau, C. V.

    2015-12-01

    The interaction of buoyancy-driven hydrocarbon plumes with the stably stratified deep-ocean environment plays a crucial role in the formation of underwater oil intrusions. As gas bubbles and oil droplets are released from an underwater oil well blowout, they induce a strong buoyancy flux that lifts entrained sea water to form an upward plume. Towards higher elevations, the stratification-induced negative buoyancy increases and eventually exceeds the gas/oil-induced buoyancy, causing the plume to decelerate and a large fraction of entrained sea water to peel off from the rising plume to form a fountain-like downward outer plume. During this peeling process, weakly buoyant particles (e.g. small oil droplets) are trapped and fall together with the detrained fluid, and then migrate horizontally at the equilibrium buoyancy depth, forming underwater oil intrusion layers. In this study, the complex plume dynamics and oil intrusion are studied using a large-eddy simulation (LES) model. The LES model captures the essential characteristics of the plume structure and the peeling/intrusion processes, and yields good agreement with prior laboratory experiments. Applying to the Deepwater Horizon oil well blowout condition, the LES model shows considerable underwater trapping and intrusion of oil droplets under various conditions, with the trapping rate significantly affected by the diameter of the oil droplet. This study is supported by Gulf of Mexico Research Initiative RFP-II research grant.

  13. Simulation of impact of oil spill in the ocean--a case study of Arabian Gulf.

    PubMed

    Verma, Parikshit; Wate, Satish R; Devotta, Sukumar

    2008-11-01

    To meet the growing energy demand worldwide, oil and gas exploration and production activities have increased rapidly both in onshore and offshore areas. The produced oil from the ocean bed is transported onshore either by ship or pipeline. This has increased the risk of oil spill in the coastal area. In order to prepare an emergency preparedness plan and to assess the magnitude of risk involved in transporting and offloading oil, oil spill simulation studies play an important role. This paper describes a simulation of oil spill in coastal bay of Arabian Gulf where new developments are taking place using MIKE 21 model. The developments include a diesel based thermal power plant near Sir Baniyas Island, which is an ecological fragile area. Based on the project activity, two probable scenarios, one for diesel leak (250 m3/h) for 1 h and the other for instantaneous spill (500 m3) are considered. The MIKE 21 model was calibrated for hydrodynamics using measured field data followed by diesel-spill simulation to track its movement in the Arabian Gulf. The results for both leak and instantaneous spill indicate that spilled diesel will not move towards the Sir Banyas Island and more than 45% of the diesel will be evaporated within 48 h of oil spill. Based on the results, a clean up and contingency plan is proposed to mitigate the adverse impacts arising due to diesel spill in the study area.

  14. Experimental determination of methane dissolution from simulated subsurface oil leakages

    NASA Astrophysics Data System (ADS)

    Sauthoff, W.; Peltzer, E. T.; Walz, P. M.; Brewer, P. G.

    2013-12-01

    Subsurface oil leakages and increased offshore drilling efforts have raised concern over the fate of hydrocarbon mixtures of oil and gas in ocean environments. Recent wellhead and pipeline failures in the Gulf of Mexico are extreme examples of this problem. Understanding the mechanism and rate of vertical transport of hydrocarbon chemical species is necessary to predict the environmental impact of subsurface leakages. In a series of controlled experiments, we carried out a deep-sea field experiment in Monterey Canyon to investigate the behavior of a gas-saturated liquid hydrocarbon mass rising from the seafloor. Aboard the R/V Rachel Carson, we used the ROV Ventana to transport a laboratory prepared volume of decane (C10H22) saturated with methane gas (CH4) to mimic a subsurface seafloor discharge. We released the oil and gas mixture into a vertically oriented open bottom glass tube followed by methane loss rate measurements both at discrete depths, and during rapid, continuous vehicle ascent from 800 to 100 m water depth to monitor changes in dissolution and bubble nucleation. Using laser Raman techniques and HD video we quantified the chemical state of the hydrocarbon fluid, including rate of methane gas dissolution. The primary methane Raman peak was readily observable within the decane C-H stretching complex. Variation in the amount of gas dissolved in the oil greatly influences oil plume density and in turn oil plume vertical rise rate. Our results show that the rise rate of the hydrocarbon mass significantly exceeds the rate at which the excess methane was lost by dissolution. This result implies that vertical transport of methane in the saturated hydrocarbon liquid phase can greatly exceed a gas bubble plume ascending the water column from a seafloor source. These results and observations may be applicable to improved understanding of the composition, distribution, and environmental fate of leaked hydrocarbon mixtures and inform remediation efforts.

  15. Large-eddy simulation of oil slicks from deep water blowouts

    NASA Astrophysics Data System (ADS)

    Yang, Di; Chamecki, Marcelo; Meneveau, Charles

    2013-11-01

    Deep water blowouts generate plumes of oil droplets and gas bubbles that rise through, and interact with various layers of the ocean. When plumes reach the ocean mixed layer (OML), the interactions among plume, Ekman Spiral and Langmuir turbulence strongly affect the final rates of dilution and bio-degradation. The present study aims at developing a large-eddy simulation (LES) capability for the study of the physical distribution and dispersion of petroleum (oil and gas) under the action of physical oceanographic processes in the OML. In the current LES, the velocity and temperature fields are simulated using a hybrid pseudo-spectral and finite-difference scheme; the oil/gas field is described by an Eulerian concentration field and it is simulated using a bounded finite-volume scheme. A variety of subgrid-scale models for the flow solver are implemented and tested. The LES capability is then applied to the simulation of oil plume dispersion in the OML, which is initially released from a point source below the thermocline. Graphical visualization of the LES results shows surface oil slick distribution consistent with the satellite and aerial images of surface oil slicks reported in the literature. Funding from the GoMRI RFP-II is gratefully acknowledged.

  16. Simulation of Anomalous Oil Filtration in a Porous Bed

    NASA Astrophysics Data System (ADS)

    Kelbaliev, G. I.; Rzaev, Ab. G.; Rasulov, S. R.; Guseinova, L. V.

    2015-03-01

    The problems of modeling the processes of filtration of anomalous structurized oils with coagulation structures present in a porous bed are considered. An equation for the filtration of Bingham fluids in a carrier bed that accounts for the dependence of the filtration rate on the pressure gradient and shear stress has been derived. Models for calculating the effective viscosity and mobility of oil depending on the change of the pressure gradient in the bed and of the concentration of particles in it have been developed. A comparison of these models with the experimental data available in the literature for various wells yielded satisfactory results.

  17. IT-OSRA: applying ensemble simulations to estimate the oil spill risk associated to operational and accidental oil spills

    NASA Astrophysics Data System (ADS)

    Sepp Neves, Antonio Augusto; Pinardi, Nadia; Martins, Flavio

    2016-08-01

    Oil Spill Risk Assessments (OSRAs) are widely employed to support decision making regarding oil spill risks. This article adapts the ISO-compliant OSRA framework developed by Sepp Neves et al. (J Environ Manag 159:158-168, 2015) to estimate risks in a complex scenario where uncertainties related to the meteo-oceanographic conditions, where and how a spill could happen exist and the risk computation methodology is not yet well established (ensemble oil spill modeling). The improved method was applied to the Algarve coast, Portugal. Over 50,000 simulations were performed in 2 ensemble experiments to estimate the risks due to operational and accidental spill scenarios associated with maritime traffic. The level of risk was found to be important for both types of scenarios, with significant seasonal variations due to the the currents and waves variability. Higher frequency variability in the meteo-oceanographic variables were also found to contribute to the level of risk. The ensemble results show that the distribution of oil concentrations found on the coast is not Gaussian, opening up new fields of research on how to deal with oil spill risks and related uncertainties.

  18. Modeling and simulation of an enzymatic reactor for hydrolysis of palm oil.

    PubMed

    Bhatia, S; Naidu, A D; Kamaruddin, A H

    1999-01-01

    Hydrolysis of palm oil has become an important process in Oleochemical industries. Therefore, an investigation was carried out for hydrolysis of palm oil to fatty acid and glycerol using immobilized lipase in packed bed reactor. The conversion vs. residence time data were used in Michaelis-Menten rate equation to evaluate the kinetic parameters. A mathematical model for the rate of palm oil hydrolysis was proposed incorporating role of external mass transfer and pore diffusion. The model was simulated for steady-state isothermal operation of immobilized lipase packed bed reactor. The experimental data were compared with the simulated results. External mass transfer was found to affect the rate of palm oil hydrolysis at higher residence time.

  19. Computer simulation of the probability that endangered whales will interact with oil spills

    SciTech Connect

    Reed, M.; Jayko, K.; Bowles, A.; Anderson, E.; Leatherwood, S.

    1987-03-01

    A numerical model system was developed to assess quantitatively the probability that endangered bowhead and gray whales will encounter spilled oil in Alaskan waters. Bowhead and gray whale migration and diving-surfacing models, and an oil-spill trajectory model comprise the system. The migration models were developed from conceptual considerations, then calibrated with and tested against observations. The movement of a whale point is governed by a random walk algorithm which stochastically follows a migratory pathway. The oil-spill model, developed under a series of other contracts, accounts for transport and spreading behavior in open water and in the presence of sea ice. Historical wind records and heavy, normal, or light ice cover data sets are selected at random to provide stochastic oil-spill scenarios for whale-oil interaction simulations.

  20. Simulating oil droplet dispersal from the Deepwater Horizon spill with a Lagrangian approach

    USGS Publications Warehouse

    North, Elizabeth W.; Schlag, Zachary; Adams, E. Eric; Sherwood, Christopher R.; He, Ruoying; Hyun, Hoon; Socolofsky, Scott A.

    2011-01-01

    An analytical multiphase plume model, combined with time-varying flow and hydrographic fields generated by the 3-D South Atlantic Bight and Gulf of Mexico model (SABGOM) hydrodynamic model, were used as input to a Lagrangian transport model (LTRANS), to simulate transport of oil droplets dispersed at depth from the recent Deepwater Horizon MC 252 oil spill. The plume model predicts a stratification-dominated near field, in which small oil droplets detrain from the central plume containing faster rising large oil droplets and gas bubbles and become trapped by density stratification. Simulated intrusion (trap) heights of ∼ 310–370 m agree well with the midrange of conductivity-temperature-depth observations, though the simulated variation in trap height was lower than observed, presumably in part due to unresolved variability in source composition (percentage oil versus gas) and location (multiple leaks during first half of spill). Simulated droplet trajectories by the SABGOM-LTRANS modeling system showed that droplets with diameters between 10 and 50 μm formed a distinct subsurface plume, which was transported horizontally and remained in the subsurface for >1 month. In contrast, droplets with diameters ≥90 μm rose rapidly to the surface. Simulated trajectories of droplets ≤50 μm in diameter were found to be consistent with field observations of a southwest-tending subsurface plume in late June 2010 reported by Camilli et al. [2010]. Model results suggest that the subsurface plume looped around to the east, with potential subsurface oil transport to the northeast and southeast. Ongoing work is focusing on adding degradation processes to the model to constrain droplet dispersal.

  1. Phases dispersion and oxygen transfer in a simulated fermentation broth containing castor oil and proteins.

    PubMed

    Pulido-Mayoral, Nancy; Galindo, Enrique

    2004-01-01

    The sizes of air bubbles and castor oil drops were studied by image analysis as a function of the concentration of soluble protein (bovine serum albumin [BSA] and lipase, as model proteins) in a three-phase system using a simulated fermentation medium (aqueous salt solution, castor oil, and air). Small amounts of proteins (<0.02 g/L) caused an important decrease in oil drops and bubbles sizes, together with a pronounced decrease in surface tension. The extent and profiles of this decrease seem to be determined by the conformation of the protein at the interface. The kLa value increased considerably for increasing concentration (up to 0.02 g/L) of the two proteins but was very different (2-fold higher for the lipase) at the highest concentrations tested (0.5 g/L), a phenomenon that can be caused by the extent to which bubbles are trapped within oil drops. PMID:15458353

  2. Oil and air dispersion in a simulated fermentation broth as a function of mycelial morphology.

    PubMed

    Lucatero, Savidra; Larralde-Corona, Claudia Patricia; Corkidi, Gabriel; Galindo, Enrique

    2003-01-01

    The culture conditions of a multiphase fermentation involving morphologically complex mycelia were simulated in order to investigate the influence of mycelial morphology (Trichoderma harzianum) on castor oil and air dispersion. Measurements of oil drops and air bubbles were obtained using an image analysis system coupled to a mixing tank. Complex interactions of the phases involved could be clearly observed. The Sauter diameter and the size distributions of drops and bubbles were affected by the morphological type of biomass (pellets or dispersed mycelia) added to the system. Larger oil drop sizes were obtained with dispersed mycelia than with pellets, as a result of the high apparent viscosity of the broth, which caused a drop in the power drawn, reducing oil drop break-up. Unexpectedly, bubble sizes observed with dispersed mycelia were smaller than with pellets, a phenomenon which can be explained by the segregation occurring at high biomass concentrations with the dispersed mycelia. Very complex oil drops were produced, containing air bubbles and a high number of structures likely consisting of small water droplets. Bubble location was influenced by biomass morphology. The percentage (in volume) of oil-trapped bubbles increased (from 32 to 80%) as dispersed mycelia concentration increased. A practically constant (32%) percentage of oil-trapped bubbles was observed with pelleted morphology at all biomass concentrations. The results evidenced the high complexity of phases interactions and the importance of mycelial morphology in such processes. PMID:12675561

  3. A framework to quantify uncertainty in simulations of oil transport in the ocean

    NASA Astrophysics Data System (ADS)

    Gonçalves, Rafael C.; Iskandarani, Mohamed; Srinivasan, Ashwanth; Thacker, W. Carlisle; Chassignet, Eric; Knio, Omar M.

    2016-04-01

    An uncertainty quantification framework is developed for the DeepC Oil Model based on a nonintrusive polynomial chaos method. This allows the model's output to be presented in a probabilistic framework so that the model's predictions reflect the uncertainty in the model's input data. The new capability is illustrated by simulating the far-field dispersal of oil in a Deepwater Horizon blowout scenario. The uncertain input consisted of ocean current and oil droplet size data and the main model output analyzed is the ensuing oil concentration in the Gulf of Mexico. A 1331 member ensemble was used to construct a surrogate for the model which was then mined for statistical information. The mean and standard deviations in the oil concentration were calculated for up to 30 days, and the total contribution of each input parameter to the model's uncertainty was quantified at different depths. Also, probability density functions of oil concentration were constructed by sampling the surrogate and used to elaborate probabilistic hazard maps of oil impact. The performance of the surrogate was constantly monitored in order to demarcate the space-time zones where its estimates are reliable.

  4. Effects of nitrate concentration in interstitial water on the bioremediation of simulated oil-polluted shorelines.

    PubMed

    Xia, Wen-xiang; Li, Jin-cheng; Song, Zhi-wen; Sun, Ying-jie

    2007-01-01

    Nutrient addition has been proved to be an effective strategy to enhance oil biodegradation in marine shorelines. To determine the optimal range of nutrient concentrations in the bioremediation of oil-polluted beaches, nitrate was added to the simulated shoreline models in the initial concentration of 1, 5 and 10 mg/L. Whenever the NO3-N concentration declined to 70% of its original value, additional nutrients were supplemented to maintain a certain range. Results showed adding nutrients increased the oil biodegradation level, the counts of petroleum degrading bacteria (PDB) and heterotrophic bacteria (HB), and the promoted efficiency varied depending on the concentration of nitrate. Oil degradation level in 5 mg/L (NO3-N) group reached as much as 84.3% accompanied with the consistently highest counts of PDB; while in 1 mg/L group oil removal efficiency was only 35.2%, and the numbers of PDB and HB were relatively low compared to the other groups supplemented with nutrients. Although counts of HB in the 10 mg/L group were remarkable, lower counts of PDB resulted in poorer oil removal efficiency (70.5%) compared to 5 mg/L group. Furthermore, it would need more NO3-N (0.371 mg) to degrade 1 mg diesel oil in the 10 mg/L group than in the 5 mg/L group (0.197 mg). In conclusion, Nitrate concentration in 5 mg/L is superior to 1 and 10 mg/L in the enhancement of diesel oil biodegradation in simulated shorelines.

  5. The accurate calculation of the band gap of liquid water by means of GW corrections applied to plane-wave density functional theory molecular dynamics simulations.

    PubMed

    Fang, Changming; Li, Wun-Fan; Koster, Rik S; Klimeš, Jiří; van Blaaderen, Alfons; van Huis, Marijn A

    2015-01-01

    Knowledge about the intrinsic electronic properties of water is imperative for understanding the behaviour of aqueous solutions that are used throughout biology, chemistry, physics, and industry. The calculation of the electronic band gap of liquids is challenging, because the most accurate ab initio approaches can be applied only to small numbers of atoms, while large numbers of atoms are required for having configurations that are representative of a liquid. Here we show that a high-accuracy value for the electronic band gap of water can be obtained by combining beyond-DFT methods and statistical time-averaging. Liquid water is simulated at 300 K using a plane-wave density functional theory molecular dynamics (PW-DFT-MD) simulation and a van der Waals density functional (optB88-vdW). After applying a self-consistent GW correction the band gap of liquid water at 300 K is calculated as 7.3 eV, in good agreement with recent experimental observations in the literature (6.9 eV). For simulations of phase transformations and chemical reactions in water or aqueous solutions whereby an accurate description of the electronic structure is required, we suggest to use these advanced GW corrections in combination with the statistical analysis of quantum mechanical MD simulations.

  6. Accurate Ab Initio Quantum Mechanics Simulations of Bi2Se3 and Bi2Te3 Topological Insulator Surfaces.

    PubMed

    Crowley, Jason M; Tahir-Kheli, Jamil; Goddard, William A

    2015-10-01

    It has been established experimentally that Bi2Te3 and Bi2Se3 are topological insulators, with zero band gap surface states exhibiting linear dispersion at the Fermi energy. Standard density functional theory (DFT) methods such as PBE lead to large errors in the band gaps for such strongly correlated systems, while more accurate GW methods are too expensive computationally to apply to the thin films studied experimentally. We show here that the hybrid B3PW91 density functional yields GW-quality results for these systems at a computational cost comparable to PBE. The efficiency of our approach stems from the use of Gaussian basis functions instead of plane waves or augmented plane waves. This remarkable success without empirical corrections of any kind opens the door to computational studies of real chemistry involving the topological surface state, and our approach is expected to be applicable to other semiconductors with strong spin-orbit coupling.

  7. Effect of a simulated oil spill on natural assemblages of marine phytoplankton enclosed in microcosms

    NASA Astrophysics Data System (ADS)

    González, J.; Figueiras, F. G.; Aranguren-Gassis, M.; Crespo, B. G.; Fernández, E.; Morán, X. A. G.; Nieto-Cid, M.

    2009-07-01

    Two microcosm experiments were carried out to simulate the effect of sporadic oil spills derived from tanker accidents on oceanic and coastal marine phytoplankton assemblages. Treatments were designed to reproduce the spill from the Prestige, which took place in Galician coastal waters (NW Iberia) in November 2002. Two different concentrations of the water soluble fraction of oil were used: low (8.6 ± 0.7 μg l -1 of chrysene equivalents) and high (23 ± 5 μg l -1 of chrysene equivalents l -1). Photosynthetic activity and chlorophyll a concentration decreased in both assemblages after 24-72 h of exposure to the two oil concentrations, even though the effect was more severe on the oceanic assemblage. These variables progressively recovered up to values close or higher than those in the controls, but the short-term negative effect of oil, which was generally stronger at the high concentration, also induced changes in the structure of the plankton community. While the biomass of nanoflagellates increased in both assemblages, oceanic picophytoplankton was drastically reduced by the addition of oil. Effects on diatoms were also observed, particularly in the coastal assemblage. The response of coastal diatoms to oil addition showed a clear dependence on size. Small diatoms (<20 μm) were apparently stimulated by oil, whereas diatoms >20 μm were only negatively affected by the high oil concentration. These differences, which could be partially due to indirect trophic interactions, might also be related to different sensitivity of species to PAHs. These results, in agreement with previous observations, additionally show that the negative effect of the water soluble fraction of oil on oceanic phytoplankton was stronger than on coastal phytoplankton.

  8. Accurate and efficient prediction of fine-resolution hydrologic and carbon dynamic simulations from coarse-resolution models

    NASA Astrophysics Data System (ADS)

    Pau, George Shu Heng; Shen, Chaopeng; Riley, William J.; Liu, Yaning

    2016-02-01

    The topography, and the biotic and abiotic parameters are typically upscaled to make watershed-scale hydrologic-biogeochemical models computationally tractable. However, upscaling procedure can produce biases when nonlinear interactions between different processes are not fully captured at coarse resolutions. Here we applied the Proper Orthogonal Decomposition Mapping Method (PODMM) to downscale the field solutions from a coarse (7 km) resolution grid to a fine (220 m) resolution grid. PODMM trains a reduced-order model (ROM) with coarse-resolution and fine-resolution solutions, here obtained using PAWS+CLM, a quasi-3-D watershed processes model that has been validated for many temperate watersheds. Subsequent fine-resolution solutions were approximated based only on coarse-resolution solutions and the ROM. The approximation errors were efficiently quantified using an error estimator. By jointly estimating correlated variables and temporally varying the ROM parameters, we further reduced the approximation errors by up to 20%. We also improved the method's robustness by constructing multiple ROMs using different set of variables, and selecting the best approximation based on the error estimator. The ROMs produced accurate downscaling of soil moisture, latent heat flux, and net primary production with O(1000) reduction in computational cost. The subgrid distributions were also nearly indistinguishable from the ones obtained using the fine-resolution model. Compared to coarse-resolution solutions, biases in upscaled ROM solutions were reduced by up to 80%. This method has the potential to help address the long-standing spatial scaling problem in hydrology and enable long-time integration, parameter estimation, and stochastic uncertainty analysis while accurately representing the heterogeneities.

  9. Accurate Monte Carlo simulations on FCC and HCP Lennard-Jones solids at very low temperatures and high reduced densities up to 1.30.

    PubMed

    Adidharma, Hertanto; Tan, Sugata P

    2016-07-01

    Canonical Monte Carlo simulations on face-centered cubic (FCC) and hexagonal closed packed (HCP) Lennard-Jones (LJ) solids are conducted at very low temperatures (0.10 ≤ T(∗) ≤ 1.20) and high densities (0.96 ≤ ρ(∗) ≤ 1.30). A simple and robust method is introduced to determine whether or not the cutoff distance used in the simulation is large enough to provide accurate thermodynamic properties, which enables us to distinguish the properties of FCC from that of HCP LJ solids with confidence, despite their close similarities. Free-energy expressions derived from the simulation results are also proposed, not only to describe the properties of those individual structures but also the FCC-liquid, FCC-vapor, and FCC-HCP solid phase equilibria.

  10. Accurate Monte Carlo simulations on FCC and HCP Lennard-Jones solids at very low temperatures and high reduced densities up to 1.30

    NASA Astrophysics Data System (ADS)

    Adidharma, Hertanto; Tan, Sugata P.

    2016-07-01

    Canonical Monte Carlo simulations on face-centered cubic (FCC) and hexagonal closed packed (HCP) Lennard-Jones (LJ) solids are conducted at very low temperatures (0.10 ≤ T∗ ≤ 1.20) and high densities (0.96 ≤ ρ∗ ≤ 1.30). A simple and robust method is introduced to determine whether or not the cutoff distance used in the simulation is large enough to provide accurate thermodynamic properties, which enables us to distinguish the properties of FCC from that of HCP LJ solids with confidence, despite their close similarities. Free-energy expressions derived from the simulation results are also proposed, not only to describe the properties of those individual structures but also the FCC-liquid, FCC-vapor, and FCC-HCP solid phase equilibria.

  11. A Simple and Accurate Method To Calculate Free Energy Profiles and Reaction Rates from Restrained Molecular Simulations of Diffusive Processes.

    PubMed

    Ovchinnikov, Victor; Nam, Kwangho; Karplus, Martin

    2016-08-25

    A method is developed to obtain simultaneously free energy profiles and diffusion constants from restrained molecular simulations in diffusive systems. The method is based on low-order expansions of the free energy and diffusivity as functions of the reaction coordinate. These expansions lead to simple analytical relationships between simulation statistics and model parameters. The method is tested on 1D and 2D model systems; its accuracy is found to be comparable to or better than that of the existing alternatives, which are briefly discussed. An important aspect of the method is that the free energy is constructed by integrating its derivatives, which can be computed without need for overlapping sampling windows. The implementation of the method in any molecular simulation program that supports external umbrella potentials (e.g., CHARMM) requires modification of only a few lines of code. As a demonstration of its applicability to realistic biomolecular systems, the method is applied to model the α-helix ↔ β-sheet transition in a 16-residue peptide in implicit solvent, with the reaction coordinate provided by the string method. Possible modifications of the method are briefly discussed; they include generalization to multidimensional reaction coordinates [in the spirit of the model of Ermak and McCammon (Ermak, D. L.; McCammon, J. A. J. Chem. Phys. 1978, 69, 1352-1360)], a higher-order expansion of the free energy surface, applicability in nonequilibrium systems, and a simple test for Markovianity. In view of the small overhead of the method relative to standard umbrella sampling, we suggest its routine application in the cases where umbrella potential simulations are appropriate.

  12. Finite element methods for enhanced oil recovery Simulation

    SciTech Connect

    Cohen, M.F.

    1985-02-01

    A general, finite element procedure for reservoir simulation is presented. This effort is directed toward improving the numerical behavior of standard upstream, or upwind, finite difference techniques, without significantly increasing the computational costs. Two methods from previous authors' work are modified and developed: upwind finite elements and the Petrov-Galerkin method. These techniques are applied in a one- and two-dimensional, surfactant/ polymer simulator. The paper sets forth the mathematical formulation and several details concerning the implementation. The results indicate that the PetrovGalerkin method does significantly reduce numericaldiffusion errors, while it retains the stability of the first-order, upwind methods. It is also relatively simple to implement. Both the upwind, and PetrovGalerkin, finite element methods demonstrate little sensitivity to grid orientation.

  13. Molecular dynamic simulation of asphaltene co-aggregation with humic acid during oil spill.

    PubMed

    Zhu, Xinzhe; Chen, Daoyi; Wu, Guozhong

    2015-11-01

    Humic acid in water and sediment plays a key role in the fate and transport of the spilled oil, but little is known about its influence on the aggregation of heavy oil asphaltenes which is adverse for remediation. Molecular dynamic simulation was performed to characterize the co-aggregation of asphaltenes (continental model and Violanthrone-79 model) with Leonardite humic acid (LHA) at the toluene-water interface and in bulk water, respectively, to simulate the transport of asphaltenes from oil to water. At the toluene-water interface, a LHA layer tended to form and bind to the water by hydrogen bonding which provided a surface for the accumulation of asphaltenes by parallel or T-shape stacking. After entering the bulk water, asphaltene aggregates stacked in parallel were tightly sequestrated inside the inner cavity of LHA aggregates following surface adsorption and structure deformation. Asphaltene aggregation in water was 2-fold higher than at the toluene-water interface. The presence of LHA increased the intensity of asphaltene aggregation by up to 83% in bulk water while relatively less influence was observed at the toluene-water interface. Overall results suggested that the co-aggregation of asphaltene with humic acid should be incorporated to the current oil spill models for better interpreting the overall environmental risks of oil spill.

  14. Large-Eddy Simulation of Oil Slicks from Deep Water Blowouts: Effects of Droplet Buoyancy and Langmuir Turbulence

    NASA Astrophysics Data System (ADS)

    Chamecki, M.; Yang, D.; Meneveau, C. V.

    2013-12-01

    Deep water blowouts generate plumes of oil droplets that rise through, and interact with various layers of the ocean. When plumes reach the ocean mixed layer (OML), the interactions among oil droplet plume, Ekman Spiral and Langmuir turbulence strongly affect the final rates of dilution and bio-degradation. The present study aims at developing a large-eddy simulation (LES) capability for the study of the physical distribution and dispersion of oil droplets under the action of physical oceanographic processes in the OML. In the current LES approach, the velocity and temperature fields are simulated using a hybrid pseudo-spectral and finite-difference scheme; the oil field is described by an Eulerian concentration field and it is simulated using a bounded finite-volume scheme. Fluid accelerations induced by buoyancy of the oil plume are included, and a number of subgrid-scale models for the flow solver are implemented and tested. The LES capability is then applied to the simulation of oil plume dispersion in the OML. Graphical visualization of the LES results shows surface oil slick distribution consistent with the satellite and aerial images of surface oil slicks reported in the literature. Different combinations of Lamgmuir turbulence and droplet size lead to different oil slick patterns at the surface and significantly impact oil concentration. Possible effects for bio-degradation are also discussed. Funding from the GoMRI RFP-II is gratefully acknowledged.

  15. Chaotic versus nonchaotic stochastic dynamics in Monte Carlo simulations: a route for accurate energy differences in N-body systems.

    PubMed

    Assaraf, Roland; Caffarel, Michel; Kollias, A C

    2011-04-15

    We present a method to efficiently evaluate small energy differences of two close N-body systems by employing stochastic processes having a stability versus chaos property. By using the same random noise, energy differences are computed from close trajectories without reweighting procedures. The approach is presented for quantum systems but can be applied to classical N-body systems as well. It is exemplified with diffusion Monte Carlo simulations for long chains of hydrogen atoms and molecules for which it is shown that the long-standing problem of computing energy derivatives is solved. PMID:21568537

  16. 3D simulation of floral oil storage in the scopa of South American insects

    NASA Astrophysics Data System (ADS)

    Ruettgers, Alexander; Griebel, Michael; Pastrik, Lars; Schmied, Heiko; Wittmann, Dieter; Scherrieble, Andreas; Dinkelmann, Albrecht; Stegmaier, Thomas; InstituteNumerical Simulation Team; Institute of Crop Science; Resource Conservation Team; Institute of Textile Technology; Process Engineering Team

    2014-11-01

    Several species of bees in South America possess structures to store and transport floral oils. By using closely spaced hairs at their back legs, the so called scopa, these bees can absorb and release oil droplets without loss. The high efficiency of this process is a matter of ongoing research. Basing on recent x-ray microtomography scans from the scopa of these bees at the Institute of Textile Technology and Process Engineering Denkendorf, we build a three-dimensional computer model. Using NaSt3DGPF, a two-phase flow solver developed at the Institute for Numerical Simulation of the University of Bonn, we perform massively parallel flow simulations with the complex micro-CT data. In this talk, we discuss the results of our simulations and the transfer of the x-ray measurement into a computer model. This research was funded under GR 1144/18-1 by the Deutsche Forschungsgemeinschaft (DFG).

  17. A New High-Speed Oil-Free Turbine Engine Rotordynamic Simulator Test Rig

    NASA Technical Reports Server (NTRS)

    Howard, Samuel A.

    2007-01-01

    A new test rig has been developed for simulating high-speed turbomachinery rotor systems using Oil-Free foil air bearing technology. Foil air bearings have been used in turbomachinery, primarily air cycle machines, for the past four decades to eliminate the need for oil lubrication. The goal of applying this bearing technology to other classes of turbomachinery has prompted the fabrication of this test rig. The facility gives bearing designers the capability to test potential bearing designs with shafts that simulate the rotating components of a target machine without the high cost of building "make-and-break" hardware. The data collected from this rig can be used to make design changes to the shaft and bearings in subsequent design iterations. This paper describes the new test rig and demonstrates its capabilities through the initial run with a simulated shaft system.

  18. Numerical simulation of pharyngeal airflow applied to obstructive sleep apnea: effect of the nasal cavity in anatomically accurate airway models.

    PubMed

    Cisonni, Julien; Lucey, Anthony D; King, Andrew J C; Islam, Syed Mohammed Shamsul; Lewis, Richard; Goonewardene, Mithran S

    2015-11-01

    Repetitive brief episodes of soft-tissue collapse within the upper airway during sleep characterize obstructive sleep apnea (OSA), an extremely common and disabling disorder. Failure to maintain the patency of the upper airway is caused by the combination of sleep-related loss of compensatory dilator muscle activity and aerodynamic forces promoting closure. The prediction of soft-tissue movement in patient-specific airway 3D mechanical models is emerging as a useful contribution to clinical understanding and decision making. Such modeling requires reliable estimations of the pharyngeal wall pressure forces. While nasal obstruction has been recognized as a risk factor for OSA, the need to include the nasal cavity in upper-airway models for OSA studies requires consideration, as it is most often omitted because of its complex shape. A quantitative analysis of the flow conditions generated by the nasal cavity and the sinuses during inspiration upstream of the pharynx is presented. Results show that adequate velocity boundary conditions and simple artificial extensions of the flow domain can reproduce the essential effects of the nasal cavity on the pharyngeal flow field. Therefore, the overall complexity and computational cost of accurate flow predictions can be reduced.

  19. Atomistic Molecular Dynamics Simulations of Crude Oil/Brine Displacement in Calcite Mesopores.

    PubMed

    Sedghi, Mohammad; Piri, Mohammad; Goual, Lamia

    2016-04-12

    Unconventional reservoirs such as hydrocarbon-bearing shale formations and ultratight carbonates generate a large fraction of oil and gas production in North America. The characteristic feature of these reservoirs is their nanoscale porosity that provides significant surface areas between the pore walls and the occupying fluids. To better assess hydrocarbon recovery from these formations, it is crucial to develop an improved insight into the effects of wall-fluid interactions on the interfacial phenomena in these nanoscale confinements. One of the important properties that controls the displacement of fluids inside the pores is the threshold capillary pressure. In this study, we present the results of an integrated series of large-scale molecular dynamics (MD) simulations performed to investigate the effects of wall-fluid interactions on the threshold capillary pressures of oil-water/brine displacements in a calcite nanopore with a square cross section. Fully atomistic models are utilized to represent crude oil, brine, and calcite in order to accommodate electrostatic interactions and H-bonding between the polar molecules and the calcite surface. To this end, we create mixtures of various polar and nonpolar organic molecules to better represent the crude oil. The interfacial tension between oil and water/brine and their contact angle on calcite surface are simulated. We study the effects of oil composition, water salinity, and temperature and pressure conditions on these properties. The threshold capillary pressure values are also obtained from the MD simulations for the calcite nanopore. We then compare the MD results against those generated using the Mayer-Stowe-Princen (MSP) method and explain the differences.

  20. Accurate determination of the Gibbs energy of Cu-Zr melts using the thermodynamic integration method in Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Harvey, J.-P.; Gheribi, A. E.; Chartrand, P.

    2011-08-01

    The design of multicomponent alloys used in different applications based on specific thermo-physical properties determined experimentally or predicted from theoretical calculations is of major importance in many engineering applications. A procedure based on Monte Carlo simulations (MCS) and the thermodynamic integration (TI) method to improve the quality of the predicted thermodynamic properties calculated from classical thermodynamic calculations is presented in this study. The Gibbs energy function of the liquid phase of the Cu-Zr system at 1800 K has been determined based on this approach. The internal structure of Cu-Zr melts and amorphous alloys at different temperatures, as well as other physical properties were also obtained from MCS in which the phase trajectory was modeled by the modified embedded atom model formalism. A rigorous comparison between available experimental data and simulated thermo-physical properties obtained from our MCS is presented in this work. The modified quasichemical model in the pair approximation was parameterized using the internal structure data obtained from our MCS and the precise Gibbs energy function calculated at 1800 K from the TI method. The predicted activity of copper in Cu-Zr melts at 1499 K obtained from our thermodynamic optimization was corroborated by experimental data found in the literature. The validity of the amplitude of the entropy of mixing obtained from the in silico procedure presented in this work was analyzed based on the thermodynamic description of hard sphere mixtures.

  1. Space simulation ultimate pressure lowered two decades by removal of diffusion pump oil contaminants during operation

    NASA Technical Reports Server (NTRS)

    Buggele, A. E.

    1973-01-01

    The complex problem why large space simulation chambers do not realize the true ultimate vacuum was investigated. Some contaminating factors affecting diffusion pump performance have been identified and some advances in vacuum/distillation/fractionation technology have been achieved which resulted in a two decade or more lower ultimate pressure. Data are presented to show the overall or individual contaminating effect of commonly used phthalate ester plasticizers of 390 to 530 molecular weight on diffusion pump performance. Methods for removing contaminants from diffusion pump silicone oil during operation and reclaiming contaminated oil by high vacuum molecular distillation are described.

  2. Investigation of oil injection into brine for the strategic petroleum reserve : hydrodynamics experiments with simulant liquids.

    SciTech Connect

    Castaneda, Jaime N.; Shollenberger, Kim Ann; Torczynski, John Robert; Cote, Raymond O.; Barney, Jeremy; O'Hern, Timothy John

    2003-10-01

    An experimental program is being conducted to study a proposed approach for oil reintroduction in the Strategic Petroleum Reserve (SPR). The goal is to assess whether useful oil is rendered unusable through formation of a stable oil-brine emulsion during reintroduction of degassed oil into the brine layer in storage caverns. This report documents the first stage of the program, in which simulant liquids are used to characterize the buoyant plume that is produced when a jet of crude oil is injected downward from a tube into brine. The experiment consists of a large transparent vessel that is a scale model of the proposed oil injection process at the SPR. An oil layer is floated on top of a brine layer. Silicon oil (Dow Corning 200{reg_sign} Fluid, 5 cSt) is used as the simulant for crude oil to allow visualization of the flow and to avoid flammability and related concerns. Sodium nitrate solution is used as the simulant for brine because it is not corrosive and it can match the density ratio between brine and crude oil. The oil is injected downward through a tube into the brine at a prescribed depth below the oil-brine interface. Flow rates are determined by scaling to match the ratio of buoyancy to momentum between the experiment and the SPR. Initially, the momentum of the flow produces a downward jet of oil below the tube end. Subsequently, the oil breaks up into droplets due to shear forces, buoyancy dominates the flow, and a plume of oil droplets rises to the interface. The interface is deflected upward by the impinging oil-brine plume. Two different diameter injection tubes were used (1/2-inch and 1-inch OD) to vary the scaling. Use of the 1-inch injection tube also assured that turbulent pipe flow was achieved, which was questionable for lower flow rates in the 1/2-inch tube. In addition, a 1/2-inch J-tube was used to direct the buoyant jet upwards rather than downwards to determine whether flow redirection could substantially reduce the oil-plume size and the

  3. 3-D Time-Accurate CFD Simulations of a Multi-Megawatt Slender Bladed HAWT under Yawed Inflow Conditions

    NASA Astrophysics Data System (ADS)

    Sayed, M.; Lutz, Th.; Krämer, E.

    2016-09-01

    In the present study numerical investigations of a generic Multi-Megawatt slender bladed Horizontal-Axis Wind Turbine (HAWT) under yawed inflow conditions were conducted. A three-dimensional URANS flow solver based on structured overlapping meshes was used. The simulations were conducted at wind speeds of 7m/sec, 11 m/sec and 15 m/sec for different yaw angles ranging from +60° to -60°. It was concluded that, for below rated wind speeds, under small yaw angles (below ±15°) the magnitudes of the blade forces are slightly increased, while under high yaw angles (above ±15°) there is a significant decrease. Moreover, the load fluctuations, for the different yaw angles, have the same frequency but different amplitude and oscillation shape. It was concluded that at the above rated wind speed of 15 m/sec, the blade aerodynamic loads are significantly affected by the yaw inflow conditions and the magnitude values of the loads are decreased with increasing yaw angle. It can be concluded that the angle of attack and the tower interference are the utmost variables affecting the yawed turbines.

  4. Time-accurate aeroelastic simulations of a wind turbine in yaw and shear using a coupled CFD-CSD method

    NASA Astrophysics Data System (ADS)

    Yu, D. O.; Kwon, O. J.

    2014-06-01

    In the present study, aeroelastic simulations of horizontal-axis wind turbine rotor blades were conducted using a coupled CFD-CSD method. The unsteady blade aerodynamic loads and the dynamic blade response due to yaw misalignment and non-uniform sheared wind were investigated. For this purpose, a CFD code solving the RANS equations on unstructured meshes and a FEM-based CSD beam solver were used. The coupling of the CFD and CSD solvers was made by exchanging the data between the two solvers in a loosely coupled manner. The present coupled CFD-CSD method was applied to the NREL 5MW reference wind turbine rotor, and the results were compared with those of CFD-alone rigid blade calculations. It was found that aeroelastic blade deformation leads to a significant reduction of blade aerodynamic loads, and alters the unsteady load behaviours, mainly due to the torsional deformation. The reduction of blade aerodynamic loads is particularly significant at the advancing rotor blade side for yawed flow conditions, and at the upper half of rotor disk where wind velocity is higher due to wind shear.

  5. Lattice-Boltzmann simulation of solvent diffusion into oil-saturated porous media.

    PubMed

    Hatiboglu, Can Ulas; Babadagli, Tayfun

    2007-12-01

    We simulated the diffusion process into oil-saturated porous media using the modified diffusion-limited aggregation and the lattice Boltzmann method algorithms. The results were matched to visual experiments for cocurrent (two sides of the model open to flow) and countercurrent (only one side of the model open to flow) diffusion for horizontally and vertically positioned samples. The model saturated with oil was exposed to pentane in order for a miscible interaction to take place. These experiments mimic the transfer between the rock matrix and fracture during gas or liquid solvent injection for enhanced oil recovery, underground waste disposal, groundwater contamination, and CO2 sequestration in naturally fractured reservoirs. Finger development at the early stages of the process was controlled by oil viscosity and the interaction type dictated by the boundary conditions. The convective transport driven by the buoyancy that was experimentally observed on vertically oriented samples and transfer driven by diffusion on the horizontal ones were captured in the LBM simulation of the process.

  6. Oil droplet plume evolution in Langmuir turbulence: a Large Eddy Simulation study

    NASA Astrophysics Data System (ADS)

    Yang, Di; Chen, Bicheng; Chamecki, Marcelo; Meneveau, Charles

    2014-11-01

    When the oil plumes from deep water blowouts reach the ocean mixed layer (OML), their fates on the sea surface are highly affected by the interactions with wind and wave-generated Langmuir turbulence in the OML. In this study, we use large eddy simulations (LES) to quantify the complex oil dispersion phenomena. We find that although the instantaneous surface oil slick patterns are very complex, the time-averaged surface oil plume can be parameterized as a Gaussian-type plume. The centerline of the surface plume is inclined clockwise (in the Northern Hemisphere) with respect to the wind and wave direction due to Ekman transport. The initial width of the mean surface plume and the inclination angle increase as the droplet size decreases. The surface plume width grows downstream, with a growth rate that varies non-monotonically with oil droplet size. Using LES data, we evaluate the eddy viscosity and eddy diffusivity following the K-profile parameterization (KPP) framework. We also evaluate stress-strain misalignments caused by Stokes drift and evaluate means of parameterizing these effects. Improvements to the KPP model will be discussed. This study is supported by a Gulf of Mexico Research Initiative research grant.

  7. Efficient and physically accurate modeling and simulation of anisoplanatic imaging through the atmosphere: a space-variant volumetric image blur method

    NASA Astrophysics Data System (ADS)

    Reinhardt, Colin N.; Ritcey, James A.

    2015-09-01

    We present a novel method for efficient and physically-accurate modeling & simulation of anisoplanatic imaging through the atmosphere; in particular we present a new space-variant volumetric image blur algorithm. The method is based on the use of physical atmospheric meteorology models, such as vertical turbulence profiles and aerosol/molecular profiles which can be in general fully spatially-varying in 3 dimensions and also evolving in time. The space-variant modeling method relies on the metadata provided by 3D computer graphics modeling and rendering systems to decompose the image into a set of slices which can be treated in an independent but physically consistent manner to achieve simulated image blur effects which are more accurate and realistic than the homogeneous and stationary blurring methods which are commonly used today. We also present a simple illustrative example of the application of our algorithm, and show its results and performance are in agreement with the expected relative trends and behavior of the prescribed turbulence profile physical model used to define the initial spatially-varying environmental scenario conditions. We present the details of an efficient Fourier-transform-domain formulation of the SV volumetric blur algorithm and detailed algorithm pseudocode description of the method implementation and clarification of some nonobvious technical details.

  8. Stable, high-order SBP-SAT finite difference operators to enable accurate simulation of compressible turbulent flows on curvilinear grids, with application to predicting turbulent jet noise

    NASA Astrophysics Data System (ADS)

    Byun, Jaeseung; Bodony, Daniel; Pantano, Carlos

    2014-11-01

    Improved order-of-accuracy discretizations often require careful consideration of their numerical stability. We report on new high-order finite difference schemes using Summation-By-Parts (SBP) operators along with the Simultaneous-Approximation-Terms (SAT) boundary condition treatment for first and second-order spatial derivatives with variable coefficients. In particular, we present a highly accurate operator for SBP-SAT-based approximations of second-order derivatives with variable coefficients for Dirichlet and Neumann boundary conditions. These terms are responsible for approximating the physical dissipation of kinetic and thermal energy in a simulation, and contain grid metrics when the grid is curvilinear. Analysis using the Laplace transform method shows that strong stability is ensured with Dirichlet boundary conditions while weaker stability is obtained for Neumann boundary conditions. Furthermore, the benefits of the scheme is shown in the direct numerical simulation (DNS) of a Mach 1.5 compressible turbulent supersonic jet using curvilinear grids and skew-symmetric discretization. Particularly, we show that the improved methods allow minimization of the numerical filter often employed in these simulations and we discuss the qualities of the simulation.

  9. Simulation of EOR (enhanced oil recovery) processes in stochastically generated permeable media

    SciTech Connect

    Waggoner, J.R.; Castillo, J.L.; Lake, L.W. . Dept. of Petroleum Engineering)

    1990-01-01

    Many enhanced oil recovery (EOR) processes involve injecting an agent, such as steam or CO{sub 2}, that is much more mobile than the resident oil. Other EOR processes attempt to improve sweep efficiency by adding polymer or surfactant to the injected water to create a favorable mobility ratio. This study examines the effect of statistically generated heterogeneity on miscible displacements at unfavorable and favorable mobility ratios. The principal goal is to delineate the effects of fingering, dispersion and channeling on volumetric sweep efficiency. Two-dimensional heterogeneous permeability fields are generated with variability (heterogeneity) and spatial correlation as characterizing parameters. Four levels of correlation and three of variability make up a 12 element matrix. At each element of the matrix, a miscible displacement simulation at unit mobility ratio shows the effect of the heterogeneity, and simulations at mobility ratios of 10 and 0.5 show the effect of viscous force differences combined with heterogeneity. 20 refs., 7 figs., 3 tabs.

  10. A dual-porosity model for simulating solute transport in oil shale

    USGS Publications Warehouse

    Glover, K.C.

    1987-01-01

    A model is described for simulating three-dimensional groundwater flow and solute transport in oil shale and associated geohydrologic units. The model treats oil shale as a dual-porosity medium by simulating flow and transport within fractures using the finite-element method. Diffusion of solute between fractures and the essentially static water of the shale matrix is simulated by including an analytical solution that acts as a source-sink term to the differential equation of solute transport. While knowledge of fracture orientation and spacing is needed to effectively use the model, it is not necessary to map the locations of individual fractures. The computer program listed in the report incorporates many of the features of previous dual-porosity models while retaining a practical approach to solving field problems. As a result the theory of solute transport is not extended in any appreciable way. The emphasis is on bringing together various aspects of solute transport theory in a manner that is particularly suited to the unusual groundwater flow and solute transport characteristics of oil shale systems. (Author 's abstract)

  11. Simulation of oil bioremediation in a tidally influenced beach: Spatiotemporal evolution of nutrient and dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Geng, Xiaolong; Pan, Zhong; Boufadel, Michel C.; Ozgokmen, Tamay; Lee, Kenneth; Zhao, Lin

    2016-04-01

    Numerical experiments of oil bioremediation of tidally influenced beach were simulated using the model BIOMARUN. Nutrient and dissolved oxygen were assumed present in a solution applied on the exposed beach face, and the concentration of these amendments was tracked throughout the beach for up to 6 months. It was found that, in comparison to natural attenuation, bioremediation increased the removal efficiency by 76% and 65% for alkanes and aromatics, respectively. Increasing the nutrient concentration in the applied solution did not always enhance biodegradation as oxygen became limiting even when the beach was originally oxygen-rich. Therefore, replenishment of oxygen to oil-contaminated zone was also essential. Stimulation of oil biodegradation was more evident in the upper and midintertidal zone of the beach, and less in the lower intertidal zone. This was due to reduced nutrient and oxygen replenishment, as very little of the amendment solution reached that zone. It was found that under continual application, most of the oil biodegraded within 2 months, while it persisted for 6 months under natural conditions. While the difference in duration suggests minimal long-term effects, there are situations where the beach would need to be cleaned for major ecological functions, such as temporary nesting or feeding for migratory birds. Biochemical retention time map (BRTM) showed that the duration of solution application was dependent upon the stimulated oil biodegradation rate. By contrast, the application rate of the amendment solution was dependent upon the subsurface extent of the oil-contaminated zone. Delivery of nutrient and oxygen into coastal beach involved complex interaction among amendment solution, groundwater, and seawater. Therefore, approaches that ignore the hydrodynamics due to tide are unlikely to provide the optimal solutions for shoreline bioremediation.

  12. Partitioning of major, minor, and trace elements during simulated in-situ oil shale retorting

    SciTech Connect

    Fox, J.P.

    1980-05-01

    The fate of inorganic constituents in Green River, Antrim, and Moroccan oil shales during in-situ retorting has been investigated. The partitioning or distribution of 50 elements to the spent shale, shale oil, retort water, and gases was studied by completing mass balances for several runs of three simulated in-situ retorts. Byproducts and products from 24 simulated in-situ retort runs were analyzed. The effect of shale origin and retort operating conditions, including temperature, particle size, atmosphere, and gas flow rate, on partitioning patterns was investigated, and the resulting data were used to develop a conceptual model of elemental partitioning during simulated in-situ retorting. Most of the 50 elements studied are not significantly mobilized during in-situ retorting. The only elements that are distributed in large quantities to the by-products are C, H, N, S, Cd, and Hg. Lesser but environmentally significant quatities of Se, As, Ni, and Co are distributed to the oils and waters, and at retorting temperatures in excess of about 900/sup 0/C, Se is mobilized to the gas phase. Mercury and Cd were the most mobile trace metals studied. About 70% of the Hg and 30% of the Cd were distributed to the gas phase. Mercury was released as a series of pulses in the last third of a retort run. Thermodynamic calculations indicated that elemental Hg is the major stable gas-phase species in all zones of an in-situ retort. The work demonstrated that elemental partitioning is controlled by the mineral residence of an element and the retort operating conditions employed. Significant differences were observed in the mobility and partitioning patterns of Green River, Antrim, and Moroccan oil shales. The only retorting conditions that had a statistically significant effect on partitioning patterns were temperature, input gas, particularly steam, and retort design and operation.

  13. Fluorescences Of Inclusion Oils With Respect To Their Maturities And Sources:Simulation In Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Chang, Y.; Huang, W.

    2007-12-01

    Evolution of fluorescence color of inclusion oils has been simulated by measuring in-situ the fluorescence of `live' oils generated from thirteen oil-prone kerogens from different depositional environments during a closed system pyrolysis in a diamond anvil cell at three heating rates (3, 8, and 25°C /min) up to 600°C. The measured fluorescence intensity of samples increases considerably within maturation intervals close to oil windows, while the fluorescence spectra of oils generated from all studied kerogens exhibit exclusively a progressive blue-shift of peak wavelengths (λmax) and red/green quotient (Q) upon increasing maturity. The observation is consistent with the maturity dependence of spectral shift trend widely recognized in natural hydrocarbon inclusions or crude oils. This study furthermore reveals that the acclaimed direction of spectral shift for inclusion oils is mostly independent of sources of their parental kerogens, implying that some reverse or anomalous trends reported in inclusion oils may be attributed to other processes subsequent to their generation, which significantly altered the fluorescence properties of oils. However, the experimental maturity corresponding to each color (λmax or Q) of oils can vary significantly (± 0.2 %Ro) among their sourced kerogens, suggesting that single fluorescence color of crude or inclusion oil is both maturity- and source-dependent and therefore may not be a good indication of its maturity. In addition, the blue-shift of cumulative oils generated from all kerogens approaches similar minima λmax around 564 nm or Q- value around 0.6 at maturity close to the middle or late stage of oil generation, implying that most late cumulative oils may exhibit similar colors. The oils generated in a maturity interval in late stage, however, can exhibit color of shorter wavelength less than the minimum.

  14. Simulation of the landfall of the Deepwater Horizon oil on the shorelines of the Gulf of Mexico.

    PubMed

    Boufadel, Michel C; Abdollahi-Nasab, Ali; Geng, Xiaolong; Galt, Jerry; Torlapati, Jagadish

    2014-08-19

    We conducted simulations of oil transport from the footprint of the Macondo Well on the water surface throughout the Gulf of Mexico, including deposition on the shorelines. We used the U.S. National Oceanic Atmospheric Administration (NOAA) model General NOAA Operational Modeling Environment (GNOME) and the same parameter values and input adopted by NOAA following the Deepwater Horizon (DWH) blowout. We found that the disappearance rate of oil off the water surface was most likely around 20% per day based on satellite-based observations of the disappearance rate of oil detected on the sea surface after the DWH wellhead was capped. The simulations and oil mass estimates suggest that the mass of oil that reached the shorelines was between 10,000 and 30,000 tons, with an expected value of 22,000 tons. More than 90% of the oil deposition occurred on the Louisiana shorelines, and it occurred in two batches. Simulations revealed that capping the well after 2 weeks would have resulted in only 30% of the total oil depositing on the shorelines, while capping after 3 weeks would have resulted in 60% deposition. Additional delay in capping after 3 weeks would have averted little additional shoreline oiling over the ensuing 4 weeks.

  15. Simulation of the landfall of the Deepwater Horizon oil on the shorelines of the Gulf of Mexico.

    PubMed

    Boufadel, Michel C; Abdollahi-Nasab, Ali; Geng, Xiaolong; Galt, Jerry; Torlapati, Jagadish

    2014-08-19

    We conducted simulations of oil transport from the footprint of the Macondo Well on the water surface throughout the Gulf of Mexico, including deposition on the shorelines. We used the U.S. National Oceanic Atmospheric Administration (NOAA) model General NOAA Operational Modeling Environment (GNOME) and the same parameter values and input adopted by NOAA following the Deepwater Horizon (DWH) blowout. We found that the disappearance rate of oil off the water surface was most likely around 20% per day based on satellite-based observations of the disappearance rate of oil detected on the sea surface after the DWH wellhead was capped. The simulations and oil mass estimates suggest that the mass of oil that reached the shorelines was between 10,000 and 30,000 tons, with an expected value of 22,000 tons. More than 90% of the oil deposition occurred on the Louisiana shorelines, and it occurred in two batches. Simulations revealed that capping the well after 2 weeks would have resulted in only 30% of the total oil depositing on the shorelines, while capping after 3 weeks would have resulted in 60% deposition. Additional delay in capping after 3 weeks would have averted little additional shoreline oiling over the ensuing 4 weeks. PMID:25068902

  16. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions

    SciTech Connect

    Reeves, T.L.; Turner, J.P.; Hasfurther, V.R.; Skinner, Q.D.

    1992-06-01

    The scope of this program is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 [times] 3.0 [times] 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by RBOSC to carry out this study. Research objectives were designed to evaluate hydrologic, geotechnical, and chemical properties and conditions which would affect the design and performance of large-scale embankments. The objectives of this research are: assess the unsaturated movement and redistribution of water and the development of potential saturated zones and drainage in disposed processed oil shale under natural and simulated climatic conditions; assess the unsaturated movement of solubles and major chemical constituents in disposed processed oil shale under natural and simulated climatic conditions; assess the physical and constitutive properties of the processed oil shale and determine potential changes in these properties caused by disposal and weathering by natural and simulated climatic conditions; assess the use of previously developed computer model(s) to describe the infiltration, unsaturated movement, redistribution, and drainage of water in disposed processed oil shale; evaluate the stability of field scale processed oil shale solid waste embankments using computer models.

  17. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions

    SciTech Connect

    Reeves, T.L.; Turner, J.P.; Hasfurther, V.R.; Skinner, Q.D.

    1992-06-01

    The scope of this program is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 {times} 3.0 {times} 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by RBOSC to carry out this study. Research objectives were designed to evaluate hydrologic, geotechnical, and chemical properties and conditions which would affect the design and performance of large-scale embankments. The objectives of this research are: assess the unsaturated movement and redistribution of water and the development of potential saturated zones and drainage in disposed processed oil shale under natural and simulated climatic conditions; assess the unsaturated movement of solubles and major chemical constituents in disposed processed oil shale under natural and simulated climatic conditions; assess the physical and constitutive properties of the processed oil shale and determine potential changes in these properties caused by disposal and weathering by natural and simulated climatic conditions; assess the use of previously developed computer model(s) to describe the infiltration, unsaturated movement, redistribution, and drainage of water in disposed processed oil shale; evaluate the stability of field scale processed oil shale solid waste embankments using computer models.

  18. A combination of streamtube and geostatical simulation methodologies for the study of large oil reservoirs

    SciTech Connect

    Chakravarty, A.; Emanuel, A.S.; Bernath, J.A.

    1997-08-01

    The application of streamtube models for reservoir simulation has an extensive history in the oil industry. Although these models are strictly applicable only to fields under voidage balance, they have proved to be useful in a large number of fields provided that there is no solution gas evolution and production. These models combine the benefit of very fast computational time with the practical ability to model a large reservoir over the course of its history. These models do not, however, directly incorporate the detailed geological information that recent experience has taught is important. This paper presents a technique for mapping the saturation information contained in a history matched streamtube model onto a detailed geostatistically derived finite difference grid. With this technique, the saturation information in a streamtube model, data that is actually statistical in nature, can be identified with actual physical locations in a field and a picture of the remaining oil saturation can be determined. Alternatively, the streamtube model can be used to simulate the early development history of a field and the saturation data then used to initialize detailed late time finite difference models. The proposed method is presented through an example application to the Ninian reservoir. This reservoir, located in the North Sea (UK), is a heterogeneous sandstone characterized by a line drive waterflood, with about 160 wells, and a 16 year history. The reservoir was satisfactorily history matched and mapped for remaining oil saturation. A comparison to 3-D seismic survey and recently drilled wells have provided preliminary verification.

  19. A fortran program for Monte Carlo simulation of oil-field discovery sequences

    USGS Publications Warehouse

    Bohling, G.C.; Davis, J.C.

    1993-01-01

    We have developed a program for performing Monte Carlo simulation of oil-field discovery histories. A synthetic parent population of fields is generated as a finite sample from a distribution of specified form. The discovery sequence then is simulated by sampling without replacement from this parent population in accordance with a probabilistic discovery process model. The program computes a chi-squared deviation between synthetic and actual discovery sequences as a function of the parameters of the discovery process model, the number of fields in the parent population, and the distributional parameters of the parent population. The program employs the three-parameter log gamma model for the distribution of field sizes and employs a two-parameter discovery process model, allowing the simulation of a wide range of scenarios. ?? 1993.

  20. Global simulations of smoke from Kuwaiti oil fires and possible effects on climate

    SciTech Connect

    Glatzmaier, G.A.; Malone, R.C.; Kao, C.Y.J.

    1991-12-31

    The Los Alamos Global Climate Model has bee used to simulate the global evolution of the Kuwaiti oil fire smoke and its potential effects on the climate. The initial simulations were done shortly before the fires were lit in January 1991. They indicated that such an event would not result in a ``Mini Nuclear Winter`` as some people were suggesting. Further simulations during the year suggested that the smoke could be responsible for subtle regional climate changes in the spring such as a 5 degree centigrade decrease in the surface temperature in Kuwait, a 10% decrease in precipitation in Saudi Arabia and a 10% increase in precipitation in the Tibetan Plateau region. These results are in qualitative agreement with the observations this year.

  1. Computer simulation of reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout

    USGS Publications Warehouse

    Hsieh, Paul

    2010-01-01

    This report describes the application of a computer model to simulate reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout. Reservoir and fluid data used for model development are based on (1) information released in BP's investigation report of the incident, (2) information provided by BP personnel during meetings in Houston, Texas, and (3) calibration by history matching to shut-in pressures measured in the capping stack during the Well Integrity Test. The model is able to closely match the measured shut-in pressures. In the simulation of the 86-day period from the blowout to shut in, the simulated reservoir pressure at the well face declines from the initial reservoir pressure of 11,850 pounds per square inch (psi) to 9,400 psi. After shut in, the simulated reservoir pressure recovers to a final value of 10,300 psi. The pressure does not recover back to the initial pressure owing to reservoir depletion caused by 86 days of oil discharge. The simulated oil flow rate declines from 63,600 stock tank barrels per day just after the Deepwater Horizon blowout to 52,600 stock tank barrels per day just prior to shut in. The simulated total volume of oil discharged is 4.92 million stock tank barrels. The overall uncertainty in the simulated flow rates and total volume of oil discharged is estimated to be + or - 10 percent.

  2. Integration of seismic methods with reservoir simulation, Pikes Peak heavy oil field, Saskatchewan

    NASA Astrophysics Data System (ADS)

    Zou, Ying

    The Pikes Peak heavy oil field has been operated by Husky Energy Ltd since 1981. Steam injection has been successfully employed to increase production. Efforts in geophysics and reservoir engineering have been made to improve interpretations in the mapping of reservoir conditions. This dissertation developed tools and a working flow for integrating the analysis of time-lapse seismic surveys with reservoir simulation, and applied them to the Pikes Peak field. Two time-lapse 2D seismic lines acquired in February 1991 and March 2000 in the eastern part of the field were carefully processed to produce wavelet and structure matched final sections. Reservoir simulation based on the field reservoir production history was carried out. It provided independent complementary information for the time-lapse seismic analysis. A rock physics procedure based on Gassmann's equation and Batzle and Wang's empirical relationship successfully linked the reservoir engineering to the seismic method. Based on the resultant seismic models, synthetic seismic sections were generated as the analogy of field seismic sections. The integrated interpretation for the Pikes Peak reservoir drew the following conclusions: The areas with a gas saturation difference, between two compared time steps, have seismic differences. Thicker gas zones correspond with large reflectivity changes on the top of the reservoir and larger traveltime delays in the seismic section. The thin gas zones only induce large reflectivity changes on the top of the reservoir, and do not have large time delays below the reservoir zone. High temperature regions also correlate with areas having large seismic energy differences. High temperature with thick gas (steam and methane) zones may be evidence for steam existence. The seismic differences at locations far from the production zone are due to the lower pressure that causes solution gas to evolve from the oil. Pressure changes propagate much faster (˜20 m in one month) than

  3. Numerical Simulation of Natural Convection of a Nanofluid in an Inclined Heated Enclosure Using Two-Phase Lattice Boltzmann Method: Accurate Effects of Thermophoresis and Brownian Forces.

    PubMed

    Ahmed, Mahmoud; Eslamian, Morteza

    2015-12-01

    Laminar natural convection in differentially heated (β = 0°, where β is the inclination angle), inclined (β = 30° and 60°), and bottom-heated (β = 90°) square enclosures filled with a nanofluid is investigated, using a two-phase lattice Boltzmann simulation approach. The effects of the inclination angle on Nu number and convection heat transfer coefficient are studied. The effects of thermophoresis and Brownian forces which create a relative drift or slip velocity between the particles and the base fluid are included in the simulation. The effect of thermophoresis is considered using an accurate and quantitative formula proposed by the authors. Some of the existing results on natural convection are erroneous due to using wrong thermophoresis models or simply ignoring the effect. Here we show that thermophoresis has a considerable effect on heat transfer augmentation in laminar natural convection. Our non-homogenous modeling approach shows that heat transfer in nanofluids is a function of the inclination angle and Ra number. It also reveals some details of flow behavior which cannot be captured by single-phase models. The minimum heat transfer rate is associated with β = 90° (bottom-heated) and the maximum heat transfer rate occurs in an inclination angle which varies with the Ra number.

  4. Numerical Simulation of Natural Convection of a Nanofluid in an Inclined Heated Enclosure Using Two-Phase Lattice Boltzmann Method: Accurate Effects of Thermophoresis and Brownian Forces.

    PubMed

    Ahmed, Mahmoud; Eslamian, Morteza

    2015-12-01

    Laminar natural convection in differentially heated (β = 0°, where β is the inclination angle), inclined (β = 30° and 60°), and bottom-heated (β = 90°) square enclosures filled with a nanofluid is investigated, using a two-phase lattice Boltzmann simulation approach. The effects of the inclination angle on Nu number and convection heat transfer coefficient are studied. The effects of thermophoresis and Brownian forces which create a relative drift or slip velocity between the particles and the base fluid are included in the simulation. The effect of thermophoresis is considered using an accurate and quantitative formula proposed by the authors. Some of the existing results on natural convection are erroneous due to using wrong thermophoresis models or simply ignoring the effect. Here we show that thermophoresis has a considerable effect on heat transfer augmentation in laminar natural convection. Our non-homogenous modeling approach shows that heat transfer in nanofluids is a function of the inclination angle and Ra number. It also reveals some details of flow behavior which cannot be captured by single-phase models. The minimum heat transfer rate is associated with β = 90° (bottom-heated) and the maximum heat transfer rate occurs in an inclination angle which varies with the Ra number. PMID:26183389

  5. An overview of uncertainty quantification techniques with application to oceanic and oil-spill simulations

    NASA Astrophysics Data System (ADS)

    Iskandarani, Mohamed; Wang, Shitao; Srinivasan, Ashwanth; Carlisle Thacker, W.; Winokur, Justin; Knio, Omar M.

    2016-04-01

    We give an overview of four different ensemble-based techniques for uncertainty quantification and illustrate their application in the context of oil plume simulations. These techniques share the common paradigm of constructing a model proxy that efficiently captures the functional dependence of the model output on uncertain model inputs. This proxy is then used to explore the space of uncertain inputs using a large number of samples, so that reliable estimates of the model's output statistics can be calculated. Three of these techniques use polynomial chaos (PC) expansions to construct the model proxy, but they differ in their approach to determining the expansions' coefficients; the fourth technique uses Gaussian Process Regression (GPR). An integral plume model for simulating the Deepwater Horizon oil-gas blowout provides examples for illustrating the different techniques. A Monte Carlo ensemble of 50,000 model simulations is used for gauging the performance of the different proxies. The examples illustrate how regression-based techniques can outperform projection-based techniques when the model output is noisy. They also demonstrate that robust uncertainty analysis can be performed at a fraction of the cost of the Monte Carlo calculation.

  6. The sequential method for the black-oil reservoir simulation on unstructured grids

    NASA Astrophysics Data System (ADS)

    Li, Baoyan; Chen, Zhangxin; Huan, Guanren

    2003-11-01

    This paper presents new results for applying the sequential solution method to the black-oil reservoir simulation with unstructured grids. The fully implicit solution method has been successfully applied to reservoir simulation with unstructured grids. However, the complexity of the fully implicit method and the irregularity of the grids result in a very complicated structure of linear equation systems (LESs) and in high computational cost to solve them. To tackle this problem, the sequential method is applied to reduce the size of the LESs. To deal with instable problems caused by the low implicit degree of this method, some practical techniques are introduced to control convergence of Newton-Raphson's iterations which are exploited in the linearization of the governing equations of the black-oil model. These techniques are tested with the benchmark problem of the ninth comparative solution project (CSP) organized by the society of petroleum engineers (SPE) and applied to field-scale models of both saturated and undersaturated reservoirs. The simulation results show that the sequential method uses as little as 20.01% of the memory for solving the LESs and 23.89% of the total computational time of the fully implicit method to reach the same precision for the undersaturated reservoirs, when the same iteration control parameters are used for both solution methods. However, for the saturated reservoirs, the sequential method must use stricter iteration control parameters to reach the same precision as the fully implicit method.

  7. Computer simulation of nonstationary thermal fields in design and operation of northern oil and gas fields

    SciTech Connect

    Vaganova, N. A.; Filimonov, M. Yu.

    2015-11-30

    A mathematical model, numerical algorithm and program code for simulation and long-term forecasting of changes in permafrost as a result of operation of a multiple well pad of northern oil and gas field are presented. In the model the most significant climatic and physical factors are taken into account such as solar radiation, determined by specific geographical location, heterogeneous structure of frozen soil, thermal stabilization of soil, possible insulation of the objects, seasonal fluctuations in air temperature, and freezing and thawing of the upper soil layer. Results of computing are presented.

  8. Impact of a simulated oil spill on benthic phototrophs and nitrogen-fixing bacteria in mudflat mesocosms.

    PubMed

    Chronopoulou, Panagiota-Myrsini; Fahy, Anne; Coulon, Frédéric; Païssé, Sandrine; Goñi-Urriza, Marisol; Peperzak, Louis; Acuña Alvarez, Laura; McKew, Boyd A; Lawson, Tracy; Timmis, Kenneth N; Duran, Robert; Underwood, Graham J C; McGenity, Terry J

    2013-01-01

    Coastal and estuarine ecosystems are highly susceptible to crude oil pollution. Therefore, in order to examine the resilience of benthic phototrophs that are pivotal to coastal ecosystem functioning, we simulated an oil spill in tidal mesocosms consisting of intact sediment cores from a mudflat at the mouth of the Colne Estuary, UK. At day 21, fluorescence imaging revealed a bloom of cyanobacteria on the surface of oiled sediment cores, and the upper 1.5 cm thick sediment had 7.2 times more cyanobacterial and 1.7 times more diatom rRNA sequences when treated with oil. Photosystem II operating efficiency (Fq'/Fm') was significantly reduced in oiled sediments at day 7, implying that the initial diatom-dominated community was negatively affected by oil, but this was no longer apparent by day 21. Oil addition significantly reduced numbers of the key deposit feeders, and the decreased grazing pressure is likely to be a major factor in the increased abundance of both diatoms and cyanobacteria. By day 5 concentrations of dissolved inorganic nitrogen were significantly lower in oiled mesocosms, likely resulting in the observed increase in nifH-containing, and therefore potentially dinitrogen-fixing, cyanobacteria. Thus, indirect effects of oil, rather than direct inhibition, are primarily responsible for altering the microphytobenthos.

  9. Trajectory of an oil spill off Goa, eastern Arabian Sea: field observations and simulations.

    PubMed

    Vethamony, P; Sudheesh, K; Babu, M T; Jayakumar, S; Manimurali, R; Saran, A K; Sharma, L H; Rajan, B; Srivastava, M

    2007-07-01

    An oil spill occurred off Goa, west coast of India, on 23 March 2005 due to collision of two vessels. In general, fair weather with weak winds prevails along the west coast of India during March. In that case, the spill would have moved slowly and reached the coast. However, in 2005 when this event occurred, relatively stronger winds prevailed, and these winds forced the spill to move away from the coast. The spill trajectory was dominated by winds rather than currents. The MIKE21 Spill Analysis model was used to simulate the spill trajectory. The observed spill trajectory and the slick area were in agreement with the model simulations. The present study illustrates the importance of having pre-validated trajectories of spill scenarios for selecting eco-sensitive regions for preparedness and planning suitable response strategies whenever spill episodes occur.

  10. Prior-knowledge-based feedforward network simulation of true boiling point curve of crude oil.

    PubMed

    Chen, C W; Chen, D Z

    2001-11-01

    Theoretical results and practical experience indicate that feedforward networks can approximate a wide class of functional relationships very well. This property is exploited in modeling chemical processes. Given finite and noisy training data, it is important to encode the prior knowledge in neural networks to improve the fit precision and the prediction ability of the model. In this paper, as to the three-layer feedforward networks and the monotonic constraint, the unconstrained method, Joerding's penalty function method, the interpolation method, and the constrained optimization method are analyzed first. Then two novel methods, the exponential weight method and the adaptive method, are proposed. These methods are applied in simulating the true boiling point curve of a crude oil with the condition of increasing monotonicity. The simulation experimental results show that the network models trained by the novel methods are good at approximating the actual process. Finally, all these methods are discussed and compared with each other.

  11. Evaluation of the Community Multiscale Air Quality Model for Simulating Winter Ozone Formation in the Uinta Basin with Intensive Oil and Gas Production

    NASA Astrophysics Data System (ADS)

    Matichuk, R.; Tonnesen, G.; Luecken, D.; Roselle, S. J.; Napelenok, S. L.; Baker, K. R.; Gilliam, R. C.; Misenis, C.; Murphy, B.; Schwede, D. B.

    2015-12-01

    The western United States is an important source of domestic energy resources. One of the primary environmental impacts associated with oil and natural gas production is related to air emission releases of a number of air pollutants. Some of these pollutants are important precursors to the formation of ground-level ozone. To better understand ozone impacts and other air quality issues, photochemical air quality models are used to simulate the changes in pollutant concentrations in the atmosphere on local, regional, and national spatial scales. These models are important for air quality management because they assist in identifying source contributions to air quality problems and designing effective strategies to reduce harmful air pollutants. The success of predicting oil and natural gas air quality impacts depends on the accuracy of the input information, including emissions inventories, meteorological information, and boundary conditions. The treatment of chemical and physical processes within these models is equally important. However, given the limited amount of data collected for oil and natural gas production emissions in the past and the complex terrain and meteorological conditions in western states, the ability of these models to accurately predict pollution concentrations from these sources is uncertain. Therefore, this presentation will focus on understanding the Community Multiscale Air Quality (CMAQ) model's ability to predict air quality impacts associated with oil and natural gas production and its sensitivity to input uncertainties. The results will focus on winter ozone issues in the Uinta Basin, Utah and identify the factors contributing to model performance issues. The results of this study will help support future air quality model development, policy and regulatory decisions for the oil and gas sector.

  12. Gas chromatographic simulated distillation-mass spectrometry for the determination of the boiling point distributions of crude oils

    PubMed

    Roussis; Fitzgerald

    2000-04-01

    The coupling of gas chromatographic simulated distillation with mass spectrometry for the determination of the distillation profiles of crude oils is reported. The method provides the boiling point distributions of both weight and volume percent amounts. The weight percent distribution is obtained from the measured total ion current signal. The total ion current signal is converted to weight percent amount by calibration with a reference crude oil of a known distillation profile. Knowledge of the chemical composition of the crude oil across the boiling range permits the determination of the volume percent distribution. The long-term repeatability is equivalent to or better than the short-term repeatability of the currently available American Society for Testing and Materials (ASTM) gas chromatographic method for simulated distillation. Results obtained by the mass spectrometric method are in very good agreement with results obtained by conventional methods of physical distillation. The compositional information supplied by the method can be used to extensively characterize crude oils.

  13. Combining DSMC Simulations and ROSINA/COPS Data of Comet 67P/Churyumov-Gerasimenko to Develop a Realistic Empirical Coma Model and to Determine Accurate Production Rates

    NASA Astrophysics Data System (ADS)

    Hansen, K. C.; Fougere, N.; Bieler, A. M.; Altwegg, K.; Combi, M. R.; Gombosi, T. I.; Huang, Z.; Rubin, M.; Tenishev, V.; Toth, G.; Tzou, C. Y.

    2015-12-01

    We have previously published results from the AMPS DSMC (Adaptive Mesh Particle Simulator Direct Simulation Monte Carlo) model and its characterization of the neutral coma of comet 67P/Churyumov-Gerasimenko through detailed comparison with data collected by the ROSINA/COPS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/COmet Pressure Sensor) instrument aboard the Rosetta spacecraft [Bieler, 2015]. Results from these DSMC models have been used to create an empirical model of the near comet coma (<200 km) of comet 67P. The empirical model characterizes the neutral coma in a comet centered, sun fixed reference frame as a function of heliocentric distance, radial distance from the comet, local time and declination. The model is a significant improvement over more simple empirical models, such as the Haser model. While the DSMC results are a more accurate representation of the coma at any given time, the advantage of a mean state, empirical model is the ease and speed of use. One use of such an empirical model is in the calculation of a total cometary coma production rate from the ROSINA/COPS data. The COPS data are in situ measurements of gas density and velocity along the ROSETTA spacecraft track. Converting the measured neutral density into a production rate requires knowledge of the neutral gas distribution in the coma. Our empirical model provides this information and therefore allows us to correct for the spacecraft location to calculate a production rate as a function of heliocentric distance. We will present the full empirical model as well as the calculated neutral production rate for the period of August 2014 - August 2015 (perihelion).

  14. Simulation study to determine the feasibility of injecting hydrogen sulfide, carbon dioxide and nitrogen gas injection to improve gas and oil recovery oil-rim reservoir

    NASA Astrophysics Data System (ADS)

    Eid, Mohamed El Gohary

    This study is combining two important and complicated processes; Enhanced Oil Recovery, EOR, from the oil rim and Enhanced Gas Recovery, EGR from the gas cap using nonhydrocarbon injection gases. EOR is proven technology that is continuously evolving to meet increased demand and oil production and desire to augment oil reserves. On the other hand, the rapid growth of the industrial and urban development has generated an unprecedented power demand, particularly during summer months. The required gas supplies to meet this demand are being stretched. To free up gas supply, alternative injectants to hydrocarbon gas are being reviewed to support reservoir pressure and maximize oil and gas recovery in oil rim reservoirs. In this study, a multi layered heterogeneous gas reservoir with an oil rim was selected to identify the most optimized development plan for maximum oil and gas recovery. The integrated reservoir characterization model and the pertinent transformed reservoir simulation history matched model were quality assured and quality checked. The development scheme is identified, in which the pattern and completion of the wells are optimized to best adapt to the heterogeneity of the reservoir. Lateral and maximum block contact holes will be investigated. The non-hydrocarbon gases considered for this study are hydrogen sulphide, carbon dioxide and nitrogen, utilized to investigate miscible and immiscible EOR processes. In November 2010, re-vaporization study, was completed successfully, the first in the UAE, with an ultimate objective is to examine the gas and condensate production in gas reservoir using non hydrocarbon gases. Field development options and proces schemes as well as reservoir management and long term business plans including phases of implementation will be identified and assured. The development option that maximizes the ultimate recovery factor will be evaluated and selected. The study achieved satisfactory results in integrating gas and oil

  15. Numerical simulations of the Macondo well blowout reveal strong control of oil flow by reservoir permeability and exsolution of gas

    PubMed Central

    Oldenburg, Curtis M.; Freifeld, Barry M.; Pruess, Karsten; Pan, Lehua; Finsterle, Stefan; Moridis, George J.

    2012-01-01

    In response to the urgent need for estimates of the oil and gas flow rate from the Macondo well MC252-1 blowout, we assembled a small team and carried out oil and gas flow simulations using the TOUGH2 codes over two weeks in mid-2010. The conceptual model included the oil reservoir and the well with a top boundary condition located at the bottom of the blowout preventer. We developed a fluid properties module (Eoil) applicable to a simple two-phase and two-component oil-gas system. The flow of oil and gas was simulated using T2Well, a coupled reservoir-wellbore flow model, along with iTOUGH2 for sensitivity analysis and uncertainty quantification. The most likely oil flow rate estimated from simulations based on the data available in early June 2010 was about 100,000 bbl/d (barrels per day) with a corresponding gas flow rate of 300 MMscf/d (million standard cubic feet per day) assuming the well was open to the reservoir over 30 m of thickness. A Monte Carlo analysis of reservoir and fluid properties provided an uncertainty distribution with a long tail extending down to 60,000 bbl/d of oil (170 MMscf/d of gas). The flow rate was most strongly sensitive to reservoir permeability. Conceptual model uncertainty was also significant, particularly with regard to the length of the well that was open to the reservoir. For fluid-entry interval length of 1.5 m, the oil flow rate was about 56,000 bbl/d. Sensitivity analyses showed that flow rate was not very sensitive to pressure-drop across the blowout preventer due to the interplay between gas exsolution and oil flow rate. PMID:21730177

  16. Hazard assessment of a simulated oil spill on intertidal areas of the St. Lawrence River with SPMD-TOX

    USGS Publications Warehouse

    Johnson, B.T.; Petty, J.D.; Huckins, J.N.; Lee, Kenneth; Gauthier, J.

    2004-01-01

    Phytoremediation in a simulated crude oil spill was studied with a "minimalistic" approach. The SPMD-TOX paradigm - a miniature passive sorptive device to collect and concentrate chemicals and microscale tests to detect toxicity - was used to monitor over time the bioavailability and potential toxicity of an oil spill. A simulated crude oil spill was initiated on an intertidal freshwater grass-wetland along the St. Lawrence River southwest of Quebec City, Quebec, Canada. Several phytoremediation treatments were investigated; to dissipate and ameliorate the spill, treatments included nutrient amendments with inorganic nitrogen sources (ammonium nitrate and sodium nitrate) and phosphate (super triple phosphate) with and without cut plants, with natural attenuation (no phytoremedial treatment) as a control. Sequestered oil residues were bioavailable in all oil-treated plots in Weeks 1 and 2. Interestingly, the samples were colored and fluoresced under ultraviolet light. In addition, microscale tests showed that sequestered residues were acutely toxic and genotoxic, as well as that they induced hepatic P450 enzymes. Analysis of these data suggested that polycyclic aromatic hydrocarbons were among the bioavailable residues sequestered. In addition, these findings suggested that the toxic bioavailable fractions of the oil spill and degradation products dissipated rapidly over time because after the second week the water column contained no oil or detectable degradation products in this riverine intertidal wetland. SPMD-TOX revealed no evidence of bioavailable oil products in Weeks 4, 6, 8, and 12. All phytoremediation efforts appeared to be ineffective in changing either the dissipation rate or the ability to ameliorate the oil toxicity. SPMD-TOX analysis of the water columns from these riverine experimental plots profiled the occurrence, dissipation, and influence of phytoremediation on the bioavailability and toxicity of oil products (parent or degradation products

  17. Gas-liquid chromatographic headspace technique for determination of vinyl chloride in corn oil and three food-simulating solvents.

    PubMed

    Diachenko, G W; Breder, C V; Brown, M E; Dennison, J L

    1977-05-01

    A gas-liquid chromatographic headspace technique for the determination of vinyl chloride (VC) in corn oil, 50% ethanol, 3% acetic acid, and n-heptane is described. These food-simulating solvents and the corn oil are placed in septum-sealed bottles and heated to 90 degrees C, and aliquots of headspace vapor are injected into a gas-liquid chromatograph equipped with a flame ionization detector. VC may be quantitated at concentrations of 1 ppb or less. This technique was used to measure the migration of VC into corn oil and 50% ethanol from 2 unplasticized polyvinyl chloride sheets containing 0.28 and 0.44 ppm residual monomer.

  18. Sorption and distribution of asphaltene, resin, aromatic and saturate fractions of heavy crude oil on quartz surface: molecular dynamic simulation.

    PubMed

    Wu, Guozhong; He, Lin; Chen, Daoyi

    2013-09-01

    The molecular scale sorption, diffusion and distribution of asphaltene, resin, aromatic and saturate fractions of heavy crude oil on quartz surface were studied using molecular dynamic simulation. Sorption of saturates on quartz decreased by 31% when temperature increased from 298 to 398K while opposite trend was observed for resins, but insignificant changes were found in asphaltenes and aromatics. Despite of this variety, the main contribution of interactions was van der Waals energy (>90%) irrespective of molecular components and temperatures. The diffusion coefficient of saturates was predicted as 10.8×10(-10)m(2)s(-1) while that of the remaining fractions was about 4×10(-10)m(2)s(-1) at 298K. The most likely oil distribution on quartz surface was that aromatics and saturates transported randomly into and out of the complex consisting of asphaltenes surrounded by resins, which was influenced by temperature. Overall, the knowledge on quartz-oil and oil-oil interactions gained in this study is essential for future risk assessment and remediation activities as previous studies on soil remediation either limited to light oil fractions with <40 carbons or treated the heavy crude oil as a single pseudo entity ignoring the interactions between oil fractions.

  19. Development of an in Vitro System to Simulate the Adsorption of Self-Emulsifying Tea (Camellia oleifera) Seed Oil.

    PubMed

    Sramala, Issara; Pinket, Wichchunee; Pongwan, Pawinee; Jarussophon, Suwatchai; Kasemwong, Kittiwut

    2016-01-01

    In this study, tea (Camellia oleifera) seed oil was formulated into self-emulsifying oil formulations (SEOF) to enhance the aqueous dispersibility and intestinal retention to achieve higher bioavailability. Self-emulsifying tea seed oils were developed by using different concentrations of lecithin in combination with surfactant blends (Span(®)80 and Tween(®)80). The lecithin/surfactant systems were able to provide clear and stable liquid formulations. The SEOF were investigated for physicochemical properties including appearance, emulsion droplets size, PDI and zeta potential. The chemical compositions of tea seed oil and SEOF were compared using GC-MS techniques. In addition, the oil adsorption measurement on artificial membranes was performed using a Franz cell apparatus and colorimetric analysis. The microscopic structure of membranes was observed with scanning electron microscopy (SEM). After aqueous dilution with fed-state simulated gastric fluid (FeSSGF), the droplet size of all SEOF was close to 200 nm with low PDI values and the zeta potential was negative. GC-MS chromatograms revealed that the chemical compositions of SEOF were not significantly different from that of the original tea seed oil. The morphological study showed that only the SEOF could form film layers. The oil droplets were extracted both from membrane treated with tea seed oil and the SEOF in order to evaluate the chemical compositions by GC-MS. PMID:27136528

  20. An Analytical Model for Simulating Heavy-Oil Recovery by Cyclic Steam Injection Using Horizontal Wells, SUPRI TR-118

    SciTech Connect

    Diwan, Utpal; Kovscek, Anthony R.

    1999-08-09

    In this investigation, existing analytical models for cyclic steam injection and oil recovery are reviewed and a new model is proposed that is applicable to horizontal wells. A new flow equation is developed for oil production during cyclic steaming of horizontal wells. The model accounts for the gravity-drainage of oil along the steam-oil interface and through the steam zone. Oil viscosity, effective permeability, geometry of the heated zone, porosity, mobile oil saturation, and thermal diffusivity of the reservoir influence the flow rate of oil in the model. The change in reservoir temperature with time is also modeled, and it results in the expected decline in oil production rate during the production cycle as the reservoir cools. Wherever appropriate, correlations and incorporated to minimize data requirements. A limited comparison to numerical simulation results agrees well, indicating that essential physics are successfully captured. Cyclic steaming appears to be a systematic met hod for heating a cold reservoir provided that a relatively uniform distribution of steam is obtained along the horizontal well during injection. A sensitivity analysis shows that the process is robust over the range of expected physical parameters.

  1. A Field-Scale Simulation of the Reversible Nanoparticle Adsorption for Enhancing Oil Recovery Using Hydrophilic Nanofluids

    NASA Astrophysics Data System (ADS)

    Cao, Liyuan

    In order to develop and apply nanotechnology in oil industry, nanoparticles transport in porous media has been studied in the past few years. Theoretical modeling were carried out to evaluate nanoparticle mobility and investigate nanoparticle retention mechanism. In this study, a simulator based on Ju and Fan's mathematical model was used to study nanoparticles transport in porous media on a reservoir scale. The simulator was verified with two simulation software, Eclipse from Schlumberger and MNM1D (Micro- and Nanoparticle transport Model in porous media in 1D geometry) developed by Tosco et al. Different injection scenarios were simulated: continuous injection, slug injection, and postflush. The effect of injection time, injection rate, and slug size on oil recovery were studied. The result discovered that when nanofluids flooding is used after water flooding as tertiary recovery method, early nanofluids injection will lead to higher oil recovery, but with more nanoparticle loss. Higher injection rate of nanofluids could help improve the flooding efficiency, but not the ultimate oil recovery for field development. Also, it can cause more nanoparticle loss. Brine water postflush is recommended when doing nanoflooding. It can significantly improve the recovery of nanoparticles, and for a homogeneous or heterogeneous reservoir, oil recovery is better compared to water flooding.

  2. Laboratory simulation of the successive aerobic and anaerobic degradation of oil products in oil-contaminated high-moor peat

    NASA Astrophysics Data System (ADS)

    Tolpeshta, I. I.; Trofimov, S. Ya.; Erkenova, M. I.; Sokolova, T. A.; Stepanov, A. L.; Lysak, L. V.; Lobanenkov, A. M.

    2015-03-01

    A model experiment has been performed on the successive aerobic and anaerobic degradation of oil products in samples of oil-contaminated peat sampled from a pine-subshrub-sphagnum bog near the Sutormin oilfield pipeline in the Yamal-Nenets autonomous district. During the incubation of oil-contaminated peat with lime and mineral fertilizers under complete flooding, favorable conditions are created for the aerobic oxidation of oil products at the beginning of the experiment and, as the redox potential decreases, for the anaerobic degradation of oil products conjugated with the reduction of N5+ and S+6 and methanogenesis. From the experimental data on the dynamics of the pH; Eh; and the NO{3/-}, NO{2/-}, and SO{4/2-} concentrations in the liquid phase of the samples, it has been found that denitrifiers significantly contributed to the biodegradation of oil products under the experimental conditions. After the end of the experiment, the content of oil products in the contaminated samples decreased by 21-26%.

  3. A technique for evaluating the oil/heavy-oil viscosity changes under ultrasound in a simulated porous medium.

    PubMed

    Hamidi, Hossein; Mohammadian, Erfan; Junin, Radzuan; Rafati, Roozbeh; Manan, Mohammad; Azdarpour, Amin; Junid, Mundzir

    2014-02-01

    Theoretically, Ultrasound method is an economical and environmentally friendly or "green" technology, which has been of interest for more than six decades for the purpose of enhancement of oil/heavy-oil production. However, in spite of many studies, questions about the effective mechanisms causing increase in oil recovery still existed. In addition, the majority of the mechanisms mentioned in the previous studies are theoretical or speculative. One of the changes that could be recognized in the fluid properties is viscosity reduction due to radiation of ultrasound waves. In this study, a technique was developed to investigate directly the effect of ultrasonic waves (different frequencies of 25, 40, 68 kHz and powers of 100, 250, 500 W) on viscosity changes of three types of oil (Paraffin oil, Synthetic oil, and Kerosene) and a Brine sample. The viscosity calculations in the smooth capillary tube were based on the mathematical models developed from the Poiseuille's equation. The experiments were carried out for uncontrolled and controlled temperature conditions. It was observed that the viscosity of all the liquids was decreased under ultrasound in all the experiments. This reduction was more significant for uncontrolled temperature condition cases. However, the reduction in viscosity under ultrasound was higher for lighter liquids compare to heavier ones. Pressure difference was diminished by decreasing in the fluid viscosity in all the cases which increases fluid flow ability, which in turn aids to higher oil recovery in enhanced oil recovery (EOR) operations. Higher ultrasound power showed higher liquid viscosity reduction in all the cases. Higher ultrasound frequency revealed higher and lower viscosity reduction for uncontrolled and controlled temperature condition experiments, respectively. In other words, the reduction in viscosity was inversely proportional to increasing the frequency in temperature controlled experiments. It was concluded that cavitation

  4. The detection and prediction for oil spill on the sea based on the infrared images

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Liu, Lei; Huang, Wei

    2016-07-01

    Detection for oil pollution is an important part of the marine environment protection in maritime security. In order to realize all-weather, rapid and accurate oil spill area detection, infrared images of oil spill on the sea is processed on account of infrared thermal imaging's visual capacity in darkness and frog. The detection for oil spill is realized and the location as well as the area of oil spill is calculated. The prediction integrated model of oil spill spreading is established and the prediction simulation for oil spill area is realized by changing the oil varieties, environmental factors and time, etc. The results show that this simulation is accurate, fast, intuitive and simple. It has certain significance for realizing the early warning of oil spill area detection automatically, intelligently and quickly.

  5. Melt-rock reaction in the asthenospheric mantle: Perspectives from high-order accurate numerical simulations in 2D and 3D

    NASA Astrophysics Data System (ADS)

    Tirupathi, S.; Schiemenz, A. R.; Liang, Y.; Parmentier, E.; Hesthaven, J.

    2013-12-01

    The style and mode of melt migration in the mantle are important to the interpretation of basalts erupted on the surface. Both grain-scale diffuse porous flow and channelized melt migration have been proposed. To better understand the mechanisms and consequences of melt migration in a heterogeneous mantle, we have undertaken a numerical study of reactive dissolution in an upwelling and viscously deformable mantle where solubility of pyroxene increases upwards. Our setup is similar to that described in [1], except we use a larger domain size in 2D and 3D and a new numerical method. To enable efficient simulations in 3D through parallel computing, we developed a high-order accurate numerical method for the magma dynamics problem using discontinuous Galerkin methods and constructed the problem using the numerical library deal.II [2]. Linear stability analyses of the reactive dissolution problem reveal three dynamically distinct regimes [3] and the simulations reported in this study were run in the stable regime and the unstable wave regime where small perturbations in porosity grows periodically. The wave regime is more relevant to melt migration beneath the mid-ocean ridges but computationally more challenging. Extending the 2D simulations in the stable regime in [1] to 3D using various combinations of sustained perturbations in porosity at the base of the upwelling column (which may result from a viened mantle), we show the geometry and distribution of dunite channel and high-porosity melt channels are highly correlated with inflow perturbation through superposition. Strong nonlinear interactions among compaction, dissolution, and upwelling give rise to porosity waves and high-porosity melt channels in the wave regime. These compaction-dissolution waves have well organized but time-dependent structures in the lower part of the simulation domain. High-porosity melt channels nucleate along nodal lines of the porosity waves, growing downwards. The wavelength scales

  6. Accurate Prediction of Hyperfine Coupling Constants in Muoniated and Hydrogenated Ethyl Radicals: Ab Initio Path Integral Simulation Study with Density Functional Theory Method.

    PubMed

    Yamada, Kenta; Kawashima, Yukio; Tachikawa, Masanori

    2014-05-13

    We performed ab initio path integral molecular dynamics (PIMD) simulations with a density functional theory (DFT) method to accurately predict hyperfine coupling constants (HFCCs) in the ethyl radical (CβH3-CαH2) and its Mu-substituted (muoniated) compound (CβH2Mu-CαH2). The substitution of a Mu atom, an ultralight isotope of the H atom, with larger nuclear quantum effect is expected to strongly affect the nature of the ethyl radical. The static conventional DFT calculations of CβH3-CαH2 find that the elongation of one Cβ-H bond causes a change in the shape of potential energy curve along the rotational angle via the imbalance of attractive and repulsive interactions between the methyl and methylene groups. Investigation of the methyl-group behavior including the nuclear quantum and thermal effects shows that an unbalanced CβH2Mu group with the elongated Cβ-Mu bond rotates around the Cβ-Cα bond in a muoniated ethyl radical, quite differently from the CβH3 group with the three equivalent Cβ-H bonds in the ethyl radical. These rotations couple with other molecular motions such as the methylene-group rocking motion (inversion), leading to difficulties in reproducing the corresponding barrier heights. Our PIMD simulations successfully predict the barrier heights to be close to the experimental values and provide a significant improvement in muon and proton HFCCs given by the static conventional DFT method. Further investigation reveals that the Cβ-Mu/H stretching motion, methyl-group rotation, methylene-group rocking motion, and HFCC values deeply intertwine with each other. Because these motions are different between the radicals, a proper description of the structural fluctuations reflecting the nuclear quantum and thermal effects is vital to evaluate HFCC values in theory to be comparable to the experimental ones. Accordingly, a fundamental difference in HFCC between the radicals arises from their intrinsic molecular motions at a finite temperature, in

  7. A novel stress-accurate FE technology for highly non-linear analysis with incompressibility constraint. Application to the numerical simulation of the FSW process

    NASA Astrophysics Data System (ADS)

    Chiumenti, M.; Cervera, M.; Agelet de Saracibar, C.; Dialami, N.

    2013-05-01

    In this work a novel finite element technology based on a three-field mixed formulation is presented. The Variational Multi Scale (VMS) method is used to circumvent the LBB stability condition allowing the use of linear piece-wise interpolations for displacement, stress and pressure fields, respectively. The result is an enhanced stress field approximation which enables for stress-accurate results in nonlinear computational mechanics. The use of an independent nodal variable for the pressure field allows for an adhoc treatment of the incompressibility constraint. This is a mandatory requirement due to the isochoric nature of the plastic strain in metal forming processes. The highly non-linear stress field typically encountered in the Friction Stir Welding (FSW) process is used as an example to show the performance of this new FE technology. The numerical simulation of the FSW process is tackled by means of an Arbitrary-Lagrangian-Eulerian (ALE) formulation. The computational domain is split into three different zones: the work.piece (defined by a rigid visco-plastic behaviour in the Eulerian framework), the pin (within the Lagrangian framework) and finally the stirzone (ALE formulation). A fully coupled thermo-mechanical analysis is introduced showing the heat fluxes generated by the plastic dissipation in the stir-zone (Sheppard rigid-viscoplastic constitutive model) as well as the frictional dissipation at the contact interface (Norton frictional contact model). Finally, tracers have been implemented to show the material flow around the pin allowing a better understanding of the welding mechanism. Numerical results are compared with experimental evidence.

  8. Accurate analysis of top gate effect of a typical triple-gate fin-type FET using three-dimensional device simulation

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Toshiyuki; Nakamura, Takeshi; Yokoyama, Norihiro; Fukuoka, Shota

    2016-06-01

    Triple-gate (TG) fin-type FETs (FinFETs) are used in advanced mass production of high-performance devices. The TG FinFET was developed from the double-gate (DG) FinFET by adding another gate for higher performance and lower variability. We analyzed the effect of the top gate of a typical TG FinFET using three-dimensional (3D) device simulation accurately for the first time. It was found that the top gate improves the drain-induced barrier lowering (DIBL) by 9%. The improvements of the threshold voltage (V th) and ON current (I on) were found to be as small as 5 and 7%, respectively. The improvement of subthreshold swing (SS) was very small at 1% despite our expectation. However, the OFF current (I off) was substantially reduced by 28% contrary to our intuitive prediction. The top gate only slightly enhances the electrostatic controllability of the channel current, so the improvements of device performance are marginal except that it has a large effect on I off reduction. It is therefore found that the biggest role of the top gate of a typical TG FinFET is substantially decreasing I off. The reason for the I off reduction is the increase in the bottleneck energy of the conduction band near the channel surface by 100 meV caused by the presence of the top gate. Since the large I off reduction is very important to suppress power consumption, our new knowledge is beneficial to develop ultralow-power devices.

  9. Ultrahigh-resolution mass spectrometry of simulated runoff from treated oil sands mature fine tailings.

    PubMed

    Headley, John V; Armstrong, Sarah A; Peru, Kerry M; Mikula, Randy J; Germida, James J; Mapolelo, Mmilili M; Rodgers, Ryan P; Marshall, Alan G

    2010-08-30

    There is interest in using mature fine tailings (MFT) in reclamation strategies of oil sands mining operations. However, simulated runoff from different dried MFT treatments is known to have elevated levels of salts, toxic ions, and naphthenic acids, and alkaline pH and it is phytotoxic to the emergent macrophyte, common reed (Phragmites australis). Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of the acidic species in the runoff confirmed that the distribution of oil sands naphthenic acids and associated oil sand acids was dependent on the MFT treatment. Furthermore, FT-ICR MS studies of the acidic species in hydroponic systems revealed that there was no plant-mediated change in the electrospray ionization mass spectra of the runoff. O(o)-containing species were prevalent (>90%), O(o)S(s) were predominant (<10% relative abundance), and O(o)N(n) were least abundant in all runoff water samples. O(o)S(s) species were predominant in all the samples investigated. The heteroatomic classes present in runoff water at greater than 1% relative abundance include: O(2)N(1), O(3)N(1), O(2), O(2)S(1) O(3), O(3)S(1), O(4), O(4)S(1), O(5), O(5)S(1), O(6), O(6)S(1), O(7), O(7)S(1), O(8) and O(8)S(1). Assuming the same response factor for all O(o) species, the O(4) class, presumably dicarboxylic acids, was generally more prevalent than the O(2) class in all samples. The O(2) class is indicative of classical naphthenic acids. However, dicarboxylic acids will form negative ions more readily than the monocarboxylic acids as there are two acidic hydrogens available for formation of these species. PMID:20635394

  10. Combined Experimental and Molecular Simulation Investigation of the Individual Effects of Corexit Surfactants on the Aerosolization of Oil Spill Matter.

    PubMed

    Zhang, Zenghui; Avij, Paria; Perkins, Matt J; Liyana-Arachchi, Thilanga P; Field, Jennifer A; Valsaraj, Kalliat T; Hung, Francisco R

    2016-08-01

    We report laboratory aerosolization experiments and classical molecular dynamics (MD) simulations, with the objective of investigating the individual effects of the two Corexit surfactants Span 80 (nonionic) and dioctyl sodium sulfosuccinate (DOSS, ionic), on the aerosolization of oil spill matter to the atmosphere. Our simulation results show that Span 80, DOSS, and the oil alkanes n-pentadecane (C15) and n-triacontane (C30) exhibit deep free energy minima at the air/seawater interface. C15 and C30 exhibit deeper free energy minima at the interface when Span 80 is present, as compared to the situation when DOSS or no surfactants are at the interface. These results suggest that Span 80 makes these oil hydrocarbons more likely to be adsorbed at the surface of seawater droplets and carried out to the atmosphere, relative to DOSS or to the situation where no surfactants are present. These simulation trends are in qualitative agreement with our experimental observations in a bubble-column setup, where larger amounts of oil hydrocarbons are ejected when Span 80 is mixed with oil and injected into the column, as compared to when DOSS is used. Our simulations also indicate that Span 80 has a larger thermodynamic incentive than DOSS to move from the seawater phase and into the air/seawater interface. This observation is also in qualitative agreement with our experimental measurements, which indicate that Span 80 is ejected in larger quantities than DOSS. Our simulations also suggest that DOSS predominantly adopts a perpendicular orientation with respect to the air/seawater interface at a dispersant to oil ratio (DOR) of 1:20, but has a slight preference to lie parallel to the interfaces at a DOR = 1:5; in both cases, DOSS molecules have their tails wide open and stretched. In contrast, Span 80 has a slight preference to align parallel to the interfaces with a coiled conformation at both DOR values. PMID:27398714

  11. Combined Experimental and Molecular Simulation Investigation of the Individual Effects of Corexit Surfactants on the Aerosolization of Oil Spill Matter.

    PubMed

    Zhang, Zenghui; Avij, Paria; Perkins, Matt J; Liyana-Arachchi, Thilanga P; Field, Jennifer A; Valsaraj, Kalliat T; Hung, Francisco R

    2016-08-01

    We report laboratory aerosolization experiments and classical molecular dynamics (MD) simulations, with the objective of investigating the individual effects of the two Corexit surfactants Span 80 (nonionic) and dioctyl sodium sulfosuccinate (DOSS, ionic), on the aerosolization of oil spill matter to the atmosphere. Our simulation results show that Span 80, DOSS, and the oil alkanes n-pentadecane (C15) and n-triacontane (C30) exhibit deep free energy minima at the air/seawater interface. C15 and C30 exhibit deeper free energy minima at the interface when Span 80 is present, as compared to the situation when DOSS or no surfactants are at the interface. These results suggest that Span 80 makes these oil hydrocarbons more likely to be adsorbed at the surface of seawater droplets and carried out to the atmosphere, relative to DOSS or to the situation where no surfactants are present. These simulation trends are in qualitative agreement with our experimental observations in a bubble-column setup, where larger amounts of oil hydrocarbons are ejected when Span 80 is mixed with oil and injected into the column, as compared to when DOSS is used. Our simulations also indicate that Span 80 has a larger thermodynamic incentive than DOSS to move from the seawater phase and into the air/seawater interface. This observation is also in qualitative agreement with our experimental measurements, which indicate that Span 80 is ejected in larger quantities than DOSS. Our simulations also suggest that DOSS predominantly adopts a perpendicular orientation with respect to the air/seawater interface at a dispersant to oil ratio (DOR) of 1:20, but has a slight preference to lie parallel to the interfaces at a DOR = 1:5; in both cases, DOSS molecules have their tails wide open and stretched. In contrast, Span 80 has a slight preference to align parallel to the interfaces with a coiled conformation at both DOR values.

  12. Oil Spill!

    ERIC Educational Resources Information Center

    Ansberry, Karen Rohrich; Morgan, Emily

    2005-01-01

    An oil spill occurs somewhere in the world almost every day of the year, and the consequences can be devastating. In this month's column, students explore the effects of oil spills on plants, animals, and the environment and investigate oil spill clean-up methods through a simulated oil spill. The activities described in this article give students…

  13. Biodegradation of marine surface floating crude oil in a large-scale field simulated experiment.

    PubMed

    Bao, Mutai; Sun, Peiyan; Yang, Xiaofei; Wang, Xinping; Wang, Lina; Cao, Lixin; Li, Fujuan

    2014-08-01

    Biodegradation of marine surface floating crude oil with hydrocarbon degrading bacteria, rhamnolipid biosurfactants, and nutrients was carried out by a large-scale field simulated experiment in this paper. After a 103 day experiment, for n-alkanes, the maximum biodegradation rate reached 71% and the results showed hydrocarbon degrading bacteria, rhamnolipid biosurfactants, and nutrients have a comprehensive effect. It also showed that rhamnolipid biosurfactants could shorten the biodegradation time through an emulsifying function; the nutrients could greatly increase the biodegradation rate by promoting HDB production. For PAHs, the chrysene series had higher weathering resistance. For the same series, the weathering resistance ability is C1- < C2- < C3- < C4-. After 53 days, no comprehensive effect occurred and more biodegradation was found for different n-alkanes in two pools which only had added rhamnolipid biosurfactants or nutrients, respectively. Except for C14, C15 and C16 sesquiterpanes, most of the steranes and terpanes had high antibiodegradability.

  14. Accurate phase-shift velocimetry in rock.

    PubMed

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models. PMID:27111139

  15. Accurate phase-shift velocimetry in rock

    NASA Astrophysics Data System (ADS)

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R.; Holmes, William M.

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.

  16. Accurate phase-shift velocimetry in rock.

    PubMed

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.

  17. Application of high-temperature simulated distillation to the residuum oil supercritical extraction process in petroleum refining

    PubMed

    Raia; Villalanti; Subramanian; Williams

    2000-01-01

    The gas chromatographic method of high-temperature simulated distillation (HTSD) is described, and the results are presented for the application of HTSD to the characterization of petroleum refinery feed and products from solvent deasphalting operations. Results are presented for refinery residual feed, deasphalted oil, and asphaltene fractions from the residual oil supercritical extraction process. Asphaltene removal from petroleum residuum using solvent deasphalting results in the improved quality and high recovery of deasphalted oil product for use as lube oil, fluid catalytic cracking, or hydrocracker feedstocks. The HTSD procedure presented here proves valuable for characterizing the fractions from the deasphalting process to obtain the percentage yield with boiling point data over the range from approximately 36 degrees C (97 degrees F) to 733 degrees C (1352 degrees F), which covers the boiling range of n-paraffins of carbon number C5 to C108.

  18. Eos modeling and reservoir simulation study of bakken gas injection improved oil recovery in the elm coulee field, Montana

    NASA Astrophysics Data System (ADS)

    Pu, Wanli

    The Bakken Formation in the Williston Basin is one of the most productive liquid-rich unconventional plays. The Bakken Formation is divided into three members, and the Middle Bakken Member is the primary target for horizontal wellbore landing and hydraulic fracturing because of its better rock properties. Even with this new technology, the primary recovery factor is believed to be only around 10%. This study is to evaluate various gas injection EOR methods to try to improve on that low recovery factor of 10%. In this study, the Elm Coulee Oil Field in the Williston Basin was selected as the area of interest. Static reservoir models featuring the rock property heterogeneity of the Middle Bakken Member were built, and fluid property models were built based on Bakken reservoir fluid sample PVT data. By employing both compositional model simulation and Todd-Longstaff solvent model simulation methods, miscible gas injections were simulated and the simulations speculated that oil recovery increased by 10% to 20% of OOIP in 30 years. The compositional simulations yielded lower oil recovery compared to the solvent model simulations. Compared to the homogeneous model, the reservoir model featuring rock property heterogeneity in the vertical direction resulted in slightly better oil recovery, but with earlier CO2 break-through and larger CO2 production, suggesting that rock property heterogeneity is an important property for modeling because it has a big effect on the simulation results. Long hydraulic fractures shortened CO2 break-through time greatly and increased CO 2 production. Water-alternating-gas injection schemes and injection-alternating-shut-in schemes can provide more options for gas injection EOR projects, especially for gas production management. Compared to CO2 injection, separator gas injection yielded slightly better oil recovery, meaning separator gas could be a good candidate for gas injection EOR; lean gas generated the worst results. Reservoir

  19. Research Capabilities for Oil-Free Turbomachinery Expanded by New Rotordynamic Simulator Facility

    NASA Technical Reports Server (NTRS)

    Howard, Samuel A.

    2004-01-01

    A new test rig has been developed for simulating high-speed turbomachinery shafting using Oil-Free foil air bearing technology. Foil air journal bearings are self-acting hydrodynamic bearings with a flexible inner sleeve surface using air as the lubricant. These bearings have been used in turbomachinery, primarily air cycle machines, for the past four decades to eliminate the need for oil lubrication. More recently, interest has been growing in applying foil bearings to aircraft gas turbine engines. They offer potential improvements in efficiency and power density, decreased maintenance costs, and other secondary benefits. The goal of applying foil air bearings to aircraft gas turbine engines prompted the fabrication of this test rig. The facility enables bearing designers to test potential bearing designs with shafts that simulate the rotating components of a target engine without the high cost of building actual flight hardware. The data collected from this rig can be used to make changes to the shaft and bearings in subsequent design iterations. The rest of this article describes the new test rig and demonstrates some of its capabilities with an initial simulated shaft system. The test rig has two support structures, each housing a foil air journal bearing. The structures are designed to accept any size foil journal bearing smaller than 63 mm (2.5 in.) in diameter. The bearing support structures are mounted to a 91- by 152-cm (3- by 5-ft) table and can be separated by as much as 122 cm (4 ft) and as little as 20 cm (8 in.) to accommodate a wide range of shaft sizes. In the initial configuration, a 9.5-cm (3.75-in.) impulse air turbine drives the test shaft. The impulse turbine, as well as virtually any number of "dummy" compressor and turbine disks, can be mounted on the shaft inboard or outboard of the bearings. This flexibility allows researchers to simulate various engine shaft configurations. The bearing support structures include a unique bearing mounting

  20. THE EFFECT OF AMOUNT OF CRUDE OIL ON EXTENT OF ITS BIODEGRADATION IN OPEN WATER- AND SANDY BEACH- LABORATORY SIMULATIONS

    EPA Science Inventory

    Lepo, J.E., C. R. Cripe, J.L. Kavanaugh, S. Zhang and G.P. Norton. 2003. Effect of Amount of Crude Oil on Extent of Its Biodegradation in Open Water- and Sandy Beach-Laboratory Simulations. Environ. Technol. 24(10):1291-1302. (ERL,GB 1109).

    We examined the biodegradation ...

  1. Development of CFD-Based Simulation Tools for In-Situ Thermal Processing of Oil Shale/Sands

    SciTech Connect

    None, None

    2012-02-01

    In our research, we are taking the novel approach of developing and applying high performance computing, computational fluid dynamics (CFD)-based simulation tools to a modified in-situ process for production of oil from oil shale. The simulation tools being developed capture the relevant physical processes and data from a large-scale system. The modified in-situ application is a pilot-scale heat transfer process inside Red Leaf Resources EcoShale capsule. We demonstrate the need to understand fluid flow behavior in the convective channels of the rubblized shale bed as convective heating greatly decreases the time required to heat the oil shale to the production temperature when compared with conductive heating alone. We have developed and implemented a geometry creation strategy for a representative section of the EcoShale capsule, developed a meshing approach to deal with the complicated geometry and produce a well-behaved mesh, analyzed the effects of boundary conditions on the simulation results, and devised a new operator splitting solution algorithm that reduces computational costs by taking advantage of the differing convective and conductive time scales occurring in the simulation. These simulation tools can be applied to a wide range of processes involving convective fluid flow heating in rubblized beds.

  2. Anesthetic Effect and Physiological Response in Olive Flounder (Paralichthys olivaceus) to Clove Oil in a Simulated Transport Experiment

    PubMed Central

    Gil, Hyun Woo; Ko, Min Gyun; Lee, Tae Ho; Park, In-Seok; Kim, Dong Soo

    2016-01-01

    The optimum concentrations of clove oil as an anesthetic for olive flounder (Paralichthys olivaceus) and the stress response of the fish to clove oil anesthesia were determined over a range of water temperatures, and investigated in a simulated transport experiment using analysis of various water and physiological parameters. While the time for induction of anesthesia decreased significantly as both the concentration of clove oil and water temperature increased, the recovery time increased significantly (P<0.05). The plasma cortisol concentration in fish at each temperature increased significantly up to 12 h following exposure (P<0.05), then decreased to 48 h (P<0.05). The DO dissolved oxygen concentrations, pH values, and the fish respiratory frequencies decreased over 6 h following exposure to clove oil in all experimental groups (P<0.05), whereas the NH4 + and CO2concentrations in all experimental groups increased up to 6 h (P<0.05). The pH values and DO concentrations increased with increasing clove oil concentration (P<0.05) in the 6 h following exposure, and the CO2 and NH4 + concentrations and the respiratory frequencies decreased with increasing clove oil concentration (P<0.05). The results of this experiment suggest that clove oil reduced the metabolic activity of olive flounder, thus reducing NH4 + excretion and O2 consumption. In conclusion, clove oil appears to be a cost-effective and efficient anesthetic that is safe for use and non-toxic to the fish and users. Its use provides the potential for improved transportation of olive flounder. PMID:27796007

  3. Characterization of naturally occurring radioactive materials in Libyan oil pipe scale using a germanium detector and Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Habib, A. S.; Shutt, A. L.; Regan, P. H.; Matthews, M. C.; Alsulaiti, H.; Bradley, D. A.

    2014-02-01

    Radioactive scale formation in various oil production facilities is acknowledged to pose a potential significant health and environmental issue. The presence of such an issue in Libyan oil fields was recognized as early as 1998. The naturally occurring radioactive materials (NORM) involved in this matter are radium isotopes (226Ra and 228Ra) and their decay products, precipitating into scales formed on the surfaces of production equipment. A field trip to a number of onshore Libyan oil fields has indicated the existence of elevated levels of specific activity in a number of locations in some of the more mature oil fields. In this study, oil scale samples collected from different parts of Libya have been characterized using gamma spectroscopy through use of a well shielded HPGe spectrometer. To avoid potential alpha-bearing dust inhalation and in accord with safe working practices at this University, the samples, contained in plastic bags and existing in different geometries, are not permitted to be opened. MCNP, a Monte Carlo simulation code, is being used to simulate the spectrometer and the scale samples in order to obtain the system absolute efficiency and then to calculate sample specific activities. The samples are assumed to have uniform densities and homogeneously distributed activity. Present results are compared to two extreme situations that were assumed in a previous study: (i) with the entire activity concentrated at a point on the sample surface proximal to the detector, simulating the sample lowest activity, and; (ii) with the entire activity concentrated at a point on the sample surface distal to the detector, simulating the sample highest activity.

  4. Quick stimulation of Alcanivorax sp. by bioemulsificant EPS2003 on microcosm oil spill simulation

    PubMed Central

    Cappello, Simone; Genovese, Maria; Denaro, Renata; Santisi, Santina; Volta, Anna; Bonsignore, Martina; Mancini, Giuseppe; Giuliano, Laura; Genovese, Lucrezia; Yakimov, Michail M.

    2014-01-01

    Oil spill microcosms experiments were carried out to evaluate the effect of bioemulsificant exopolysaccharide (EPS2003) on quick stimulation of hydrocarbonoclastic bacteria. Early hours of oil spill, were stimulated using an experimental seawater microcosm, supplemented with crude oil and EPS2003 (SW+OIL+EPS2003); this system was monitored for 2 days and compared to control microcosm (only oil-polluted seawater, SW+OIL). Determination of bacterial abundance, heterotrophic cultivable and hydrocarbon-degrading bacteria were carried out. Community composition of marine bacterioplankton was determined by 16S rRNA gene clone libraries. Data obtained indicated that bioemulsificant addition stimulated an increase of total bacterial abundance and, in particular, selection of bacteria related to Alcanivorax genus; confirming that EPS2003 could be used for the dispersion of oil slicks and could stimulate the selection of marine hydrocarbon degraders thus increasing bioremediation process. PMID:25763036

  5. Cracking of simulated oil refinery off-gas over a coal char, petroleum coke, and quartz

    SciTech Connect

    Yuan Zhang; Jin-hu Wu; Dong-ke Zhang

    2008-03-15

    The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only over the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.

  6. Simulation of detonation of ammonium nitrate fuel oil mixture confined by aluminum: edge angles for DSD

    SciTech Connect

    Short, Mark; Quirk, James J; Kiyanda, Charles B; Jackson, Scott I; Briggs, Matthew E; Shinas, Micheal A

    2010-01-01

    Non-ideal high explosives are typically porous, low-density materials with a low detonation velocity (3--5 km/s) and long detonation reaction zone ({approx} cms). As a result, the interaction of a non-ideal high explosive with an inert confiner can be markedly different than for a conventional high explosive. Issues arise, for example, with light stiff confiners where the confiner can drive the high explosive (HE) through a Prandtl-Meyer fan at the HE/confiner interface rather than the HE driving the confiner. For a non-ideal high explosive confined by a high sound speed inert such that the detonation velocity is lower than the inert sound speed, the flow is subsonic and thus shockless in the confiner. In such cases, the standard detonation shock dynamics methodology, which requires a positive edge-angle be specified at the HE/confiner interface in order that the detonation shape be divergent, cannot be directly utilized. In order to study how detonation shock dynamics can be utilized in such cases, numerical simulations of the detonation of ammonium nitrate-fuel oil (ANFO) confined by aluminum 6061 are conducted.

  7. Macro-econometric model of the Nigerian economy: a simulated analysis of oil shocks in a development context

    SciTech Connect

    Usip, E.E.E.

    1984-01-01

    The precarious position of Nigeria in being a one-resource (oil) based economy in terms of revenue generation has become a major cause of concern for the experts and political pundits. In this study, the author seeks to explore further the empirical basis for this concern in two stages. First, a macro-econometric model of Nigeria was constructed and evaluated. The model highlights the various channels through which the oil sector influences the rest of the economy. Economic theory, econometric techniques, existing fund of knowledge in the practice, computer simulation, and the institutional framework of Nigeria were brought to bear upon the modeling process. In the second stage, the resulting simulation model was used to examine the sensitivity of the economy to the leading sector (oil) as well as the growth potential of Nigeria up to 1986. The crucial question that was addressed is: will the oil sector be able to support a continuing economic growth of Nigeria in the absence of policy initiatives to diversify the revenue base of the economy. Although the empirical findings are hypothetical, they do have far-reaching implications for Nigeria's growth prospects and political stability.

  8. Oil plumes and dispersion in Langmuir, upper-ocean turbulence: Large-eddy simulations and K-profile parameterization

    NASA Astrophysics Data System (ADS)

    Yang, Di; Chen, Bicheng; Chamecki, Marcelo; Meneveau, Charles

    2015-07-01

    Once oil plumes such as those originating from underwater blowouts reach the ocean mixed layer (OML), their near-surface dispersion is influenced heavily by wind and wave-generated Langmuir turbulence. In this study, the complex oil spill dispersion process is modeled using large-eddy simulation (LES). The mean plume dispersion is characterized by performing statistical analysis of the resulting fields from the LES data. Although the instantaneous oil concentration exhibits high intermittency with complex spatial patterns such as Langmuir-induced striations, it is found that the time-averaged oil distribution can still be described quite well by smooth Gaussian-type plumes. LES results show that the competition between droplet rise velocity and vertical turbulent diffusion due to Langmuir turbulence is crucial in determining both the dilution rate and overall direction of transport of oil plumes in the OML. The smoothness of the mean plume makes it feasible to aim at modeling the oil dispersion using Reynolds-averaged type formulations, such as the K-profile parameterization (KPP) with sufficient vertical resolution to capture vertical profiles in the OML. Using LES data, we evaluate the eddy viscosity and eddy diffusivity following the KPP framework. We assess the performance of previous KPP models for pure shear turbulence and Langmuir turbulence by comparing them with the LES data. Based on the assessment a modified KPP model is proposed, which shows improved overall agreement with the LES results for both the eddy viscosity and the eddy diffusivity of the oil dispersion under a variety of flow conditions and droplet sizes.

  9. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions

    SciTech Connect

    Turner, J.P.; Hasfurther, V.

    1992-05-04

    The scope of the research program and the continuation is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 [times] 3.0 [times] 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by Rio Blanco Oil Shale Co., Inc. (RBOSC) through a separate cooperative agreement with the University of Wyoming (UW) to carry out this study. Three of the lysimeters were established at the RBOSC Tract C-a in the Piceance Basin of Colorado. Two lysimeters were established in the Environmental Simulation Laboratory (ESL) at UW. The ESL was specifically designed and constructed so that a large range of climatic conditions could be physically applied to the processed oil shale which was filled in the lysimeter cells.

  10. Source attribution of methane emissions from global oil and gas production: results of bottom-up simulations over three decades

    NASA Astrophysics Data System (ADS)

    Höglund-Isaksson, Lena

    2016-04-01

    Existing bottom-up emission inventories of historical methane and ethane emissions from global oil and gas systems do not well explain year-on-year variations estimated by top-down models from atmospheric measurements. This paper develops a bottom-up methodology which allows for country- and year specific source attribution of methane and ethane emissions from global oil and natural gas production for the period 1980 to 2012. The analysis rests on country-specific simulations of associated gas flows which are converted into methane and ethane emissions. The associated gas flows are constructed from country-specific information on oil and gas production and associated gas generation and recovery, and coupled with generic assumptions to bridge regional information gaps on the fractions of unrecovered associated gas that is vented instead of flared. Summing up emissions from associated gas flows with global estimates of emissions from unintended leakage and natural gas transmission and distribution, the resulting global emissions of methane and ethane from oil and gas systems are reasonably consistent with corresponding estimates from top-down models. Also revealed is that the fall of the Soviet Union in 1990 had a significant impact on methane and ethane emissions from global oil and gas systems.

  11. Design, fabrication, operation and Aspen simulation of oil shale pyrolysis and biomass gasification process using a moving bed downdraft reactor

    NASA Astrophysics Data System (ADS)

    Golpour, Hassan

    Energy is the major facilitator of the modern life. Every developed and developing economy requires access to advanced sources of energy to support its growth and prosperity. Declining worldwide crude oil reserves and increasing energy needs has focused attention on developing existing unconventional fossil fuels like oil shale and renewable resources such as biomass. Sustainable, renewable and reliable resources of domestically produced biomass comparing to wind and solar energy is a sensible motivation to establish a small-scale power plant using biomass as feed to supply electricity demand and heat for rural development. The work in Paper I focuses on the possibility of water pollution from spent oil shale which should be studied before any significant commercial production is attempted. In Paper II, the proposed Aspen models for oil shale pyrolysis is to identify the key process parameters for the reactor and optimize the rate of production of syncrude from oil shale. The work in Paper III focuses on (1) Design and operation of a vertical downdraft reactor, (2) Establishing an optimum operating methodology and parameters to maximize syngas production through process testing. Finally in Paper IV, a proposed Aspen model for biomass gasification simulates a real biomass gasification system discussed in Paper III.

  12. A Monte Carlo simulation based two-stage adaptive resonance theory mapping approach for offshore oil spill vulnerability index classification.

    PubMed

    Li, Pu; Chen, Bing; Li, Zelin; Zheng, Xiao; Wu, Hongjing; Jing, Liang; Lee, Kenneth

    2014-09-15

    In this paper, a Monte Carlo simulation based two-stage adaptive resonance theory mapping (MC-TSAM) model was developed to classify a given site into distinguished zones representing different levels of offshore Oil Spill Vulnerability Index (OSVI). It consisted of an adaptive resonance theory (ART) module, an ART Mapping module, and a centroid determination module. Monte Carlo simulation was integrated with the TSAM approach to address uncertainties that widely exist in site conditions. The applicability of the proposed model was validated by classifying a large coastal area, which was surrounded by potential oil spill sources, based on 12 features. Statistical analysis of the results indicated that the classification process was affected by multiple features instead of one single feature. The classification results also provided the least or desired number of zones which can sufficiently represent the levels of offshore OSVI in an area under uncertainty and complexity, saving time and budget in spill monitoring and response. PMID:25044043

  13. Simulation of scenarios of oil droplet formation from the Deepwater Horizon blowout.

    PubMed

    Zhao, Lin; Boufadel, Michel C; Adams, Eric; Socolofsky, Scott A; King, Thomas; Lee, Kenneth; Nedwed, Timothy

    2015-12-15

    Knowledge of the droplet size distribution (DSD) from the Deepwater Horizon (DWH) blowout is an important step in predicting the fate and transport of the released oil. Due to the absence of measurements of the DSD from the DWH incident, we considered herein hypothetical scenarios of releases that explore the realistic parameter space using a thoroughly calibrated DSD model, VDROP-J, and we attempted to provide bounds on the range of droplet sizes from the DWH blowout within 200 m of the wellhead. The scenarios include conditions without and with the presence of dispersants, different dispersant treatment efficiencies, live oil and dead oil properties, and varying oil flow rate, gas flow rate, and orifice diameter. The results, especially for dispersant-treated oil, are very different from recent modeling studies in the literature. PMID:26581815

  14. The use of artificial neural network (ANN) for the prediction and simulation of oil degradation in wastewater by AOP.

    PubMed

    Mustafa, Yasmen A; Jaid, Ghydaa M; Alwared, Abeer I; Ebrahim, Mothana

    2014-06-01

    The application of advanced oxidation process (AOP) in the treatment of wastewater contaminated with oil was investigated in this study. The AOP investigated is the homogeneous photo-Fenton (UV/H2O2/Fe(+2)) process. The reaction is influenced by the input concentration of hydrogen peroxide H2O2, amount of the iron catalyst Fe(+2), pH, temperature, irradiation time, and concentration of oil in the wastewater. The removal efficiency for the used system at the optimal operational parameters (H2O2 = 400 mg/L, Fe(+2) = 40 mg/L, pH = 3, irradiation time = 150 min, and temperature = 30 °C) for 1,000 mg/L oil load was found to be 72%. The study examined the implementation of artificial neural network (ANN) for the prediction and simulation of oil degradation in aqueous solution by photo-Fenton process. The multilayered feed-forward networks were trained by using a backpropagation algorithm; a three-layer network with 22 neurons in the hidden layer gave optimal results. The results show that the ANN model can predict the experimental results with high correlation coefficient (R (2) = 0.9949). The sensitivity analysis showed that all studied variables (H2O2, Fe(+2), pH, irradiation time, temperature, and oil concentration) have strong effect on the oil degradation. The pH was found to be the most influential parameter with relative importance of 20.6%. PMID:24595749

  15. A sub-canopy structure for simulating oil palm in the Community Land Model: phenology, allocation and yield

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Roupsard, O.; Bernoux, M.; Le Maire, G.; Panferov, O.; Kotowska, M. M.; Knohl, A.

    2015-06-01

    Land surface modelling has been widely used to characterize the two-way interactions between climate and human activities in terrestrial ecosystems such as deforestation, agricultural expansion, and urbanization. Towards an effort to quantify the effects of forests to oil palm conversion occurring in the tropics on land-atmosphere carbon, water and energy fluxes, we introduce a new perennial crop plant functional type (PFT) for oil palm. Due to the modular and sequential nature of oil palm growth (around 40 stacked phytomers) and yield (fruit bunches axillated on each phytomer), we developed a specific sub-canopy structure for simulating palm's growth and yield within the framework of the Community Land Model (CLM4.5). In this structure each phytomer has its own prognostic leaf growth and fruit yield capacity like a PFT but with shared stem and root components among all phytomers. Phenology and carbon and nitrogen allocation operate on the different phytomers in parallel but at unsynchronized steps, so that multiple fruit yields per annum are enabled in terms of carbon and nitrogen outputs. An important phenological phase is identified for the palm PFT - the storage growth period of bud and "spear" leaves which are photosynthetically inactive before expansion. Agricultural practices such as transplanting, fertilization, and leaf pruning are represented. Parameters introduced for the new PFT were calibrated and validated with field measurements of leaf area index (LAI) and yield from Sumatra, Indonesia. In calibration with a mature oil palm plantation, the cumulative yields from 2005 to 2014 matched perfectly between simulation and observation (mean percentage error = 4 %). Simulated inter-annual dynamics of PFT-level and phytomer-level LAI were both within the range of field measurements. Validation from eight independent oil palm sites shows the ability of the model to adequately predict the average leaf growth and fruit yield across sites but also indicates that

  16. Numerical Simulation of Potential Groundwater Contaminant Pathways from Hydraulically Fractured Oil Shale in the Nevada Basin and Range Province

    NASA Astrophysics Data System (ADS)

    Rybarski, S.; Pohll, G.; Pohlmann, K.; Plume, R.

    2014-12-01

    In recent years, hydraulic fracturing (fracking) has become an increasingly popular method for extraction of oil and natural gas from tight formations. Concerns have been raised over a number of environmental risks associated with fracking, including contamination of groundwater by fracking fluids, upwelling of deep subsurface brines, and methane migration. Given the potentially long time scale for contaminant transport associated with hydraulic fracturing, numerical modeling remains the best practice for risk assessment. Oil shale in the Humboldt basin of northeastern Nevada has now become a target for hydraulic fracturing operations. Analysis of regional and shallow groundwater flow is used to assess several potential migration pathways specific to the geology and hydrogeology of this basin. The model domain in all simulations is defined by the geologic structure of the basin as determined by deep oil and gas well bores and formation outcrops. Vertical transport of gaseous methane along a density gradient is simulated in TOUGH2, while fluid transport along faults and/or hydraulic fractures and lateral flow through more permeable units adjacent to the targeted shale are modeled in FEFLOW. Sensitivity analysis considers basin, fault, and hydraulic fracturing parameters, and results highlight key processes that control fracking fluid and methane migration and time scales under which it might occur.

  17. Western oil shale development: a technology assessment. Volume 7: an ecosystem simulation of perturbations applied to shale oil development

    SciTech Connect

    Not Available

    1982-05-01

    Progress is outlined on activities leading toward evaluation of ecological and agricultural impacts of shale oil development in the Piceance Creek Basin region of northwestern Colorado. After preliminary review of the problem, it was decided to use a model-based calculation approach in the evaluation. The general rationale and objectives of this approach are discussed. Previous studies were examined to characterize climate, soils, vegetation, animals, and ecosystem response units. System function was methodically defined by developing a master list of variables and flows, structuring a generalized system flow diagram, constructing a flow-effects matrix, and conceptualizing interactive spatial units through spatial matrices. The process of developing individual mathematical functions representing the flow of matter and energy through the various system variables in different submodels is discussed. The system model diagram identified 10 subsystems which separately account for flow of soil temperatures, soil water, herbaceous plant biomass, shrubby plant biomass, tree cover, litter biomass, shrub numbers, animal biomass, animal numbers, and land area. Among these coupled subsystems there are 45 unique kinds of state variables and 150 intra-subsystem flows. The model is generalizeable and canonical so that it can be expanded, if required, by disaggregating some of the system state variables and allowing for multiple ecological response units. It integrates information on climate, surface water, ecology, land reclamation, air quality, and solid waste as it is being developed by several other task groups.

  18. Numerical Model Simulating the Transport of Oil with Deep Water Emission Sources in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Montiel, M.

    2015-12-01

    Inaccuracies found while attempting to numerically simulate the Deepwater Horizon 2010 (DH2010) spill have shown the difficulties encountered in determining the path and destination of oil spills which emissions sources lie in deep waters (~ 1500m). This work aims to contribute to the understanding of this phenomenon by implementing a passive tracer in the hydrodynamic model ROMS. The DH2010 spill was selected as study case because its records allow to quantify the benefits of the simulation method proposed here. This work presents how this simulation was implemented, the statistical schemes and the results obtained for the DH2010 spill associated areas, plus other areas of interest close to the Mexican Coast in the Gulf of Mexico.

  19. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries

    NASA Astrophysics Data System (ADS)

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-09-01

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs.

  20. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries.

    PubMed

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-01-01

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs. PMID:27628131

  1. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries

    PubMed Central

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-01-01

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs. PMID:27628131

  2. Effects of chemical dispersants on oil spill drift paths in the German Bight—probabilistic assessment based on numerical ensemble simulations

    NASA Astrophysics Data System (ADS)

    Schwichtenberg, Fabian; Callies, Ulrich; Groll, Nikolaus; Maßmann, Silvia

    2016-06-01

    Oil dispersed in the water column remains sheltered from wind forcing, so that an altered drift path is a key consequence of using chemical dispersants. In this study, ensemble simulations were conducted based on 7 years of simulated atmospheric and marine conditions, evaluating 2,190 hypothetical spills from each of 636 cells of a regular grid covering the inner German Bight (SE North Sea). Each simulation compares two idealized setups assuming either undispersed or fully dispersed oil. Differences are summarized in a spatial map of probabilities that chemical dispersant applications would help prevent oil pollution from entering intertidal coastal areas of the Wadden Sea. High probabilities of success overlap strongly with coastal regions between 10 m and 20 m water depth, where the use of chemical dispersants for oil spill response is a particularly contentious topic. The present study prepares the ground for a more detailed net environmental benefit analysis (NEBA) accounting also for toxic effects.

  3. MO-A-BRD-10: A Fast and Accurate GPU-Based Proton Transport Monte Carlo Simulation for Validating Proton Therapy Treatment Plans

    SciTech Connect

    Wan Chan Tseung, H; Ma, J; Beltran, C

    2014-06-15

    Purpose: To build a GPU-based Monte Carlo (MC) simulation of proton transport with detailed modeling of elastic and non-elastic (NE) protonnucleus interactions, for use in a very fast and cost-effective proton therapy treatment plan verification system. Methods: Using the CUDA framework, we implemented kernels for the following tasks: (1) Simulation of beam spots from our possible scanning nozzle configurations, (2) Proton propagation through CT geometry, taking into account nuclear elastic and multiple scattering, as well as energy straggling, (3) Bertini-style modeling of the intranuclear cascade stage of NE interactions, and (4) Simulation of nuclear evaporation. To validate our MC, we performed: (1) Secondary particle yield calculations in NE collisions with therapeutically-relevant nuclei, (2) Pencil-beam dose calculations in homogeneous phantoms, (3) A large number of treatment plan dose recalculations, and compared with Geant4.9.6p2/TOPAS. A workflow was devised for calculating plans from a commercially available treatment planning system, with scripts for reading DICOM files and generating inputs for our MC. Results: Yields, energy and angular distributions of secondaries from NE collisions on various nuclei are in good agreement with the Geant4.9.6p2 Bertini and Binary cascade models. The 3D-gamma pass rate at 2%–2mm for 70–230 MeV pencil-beam dose distributions in water, soft tissue, bone and Ti phantoms is 100%. The pass rate at 2%–2mm for treatment plan calculations is typically above 98%. The net computational time on a NVIDIA GTX680 card, including all CPU-GPU data transfers, is around 20s for 1×10{sup 7} proton histories. Conclusion: Our GPU-based proton transport MC is the first of its kind to include a detailed nuclear model to handle NE interactions on any nucleus. Dosimetric calculations demonstrate very good agreement with Geant4.9.6p2/TOPAS. Our MC is being integrated into a framework to perform fast routine clinical QA of pencil

  4. Model simulation of the drift and spread of the Aegean Sea oil spill near La Coruna

    SciTech Connect

    Daniel, P.

    1994-12-31

    On the 3 December 1992 the Greek oil tanker Aegean Sea ran aground at Torre de Hercules near the entrance to the Ria de Coruna and La Coruna harbor, Spain. The 291 m tanker of 114,036-dwt carrying 79,096 tons of Brent type crude oil, broke up and exploded. Practically all of the oil was released into the sea. Over 200 km of shore was affected. A two-dimensional depth-integrated model on a .25 ft. x .25 ft. grid was implemented with the capability of predicting wind driven movements in the area of La Coruna. It is driven by meteorological analysis from the European Centre for Medium Range Weather Forecasts (ECMRWF) global numerical weather prediction model.

  5. Application of MODFLOW for oil reservoir simulation during the Deepwater Horizon Crisis

    USGS Publications Warehouse

    Hsieh, Paul A.

    2011-01-01

    When the Macondo well was shut in on July 15, 2010, the shut-in pressure recovered to a level that indicated the possibility of oil leakage out of the well casing into the surrounding formation. Such a leak could initiate a hydraulic fracture that might eventually breach the seafloor, resulting in renewed and uncontrolled oil flow into the Gulf of Mexico. To help evaluate whether or not to reopen the well, a MODFLOW model was constructed within 24 h after shut in to analyze the shut-in pressure. The model showed that the shut-in pressure can be explained by a reasonable scenario in which the well did not leak after shut in. The rapid response provided a scientific analysis for the decision to keep the well shut, thus ending the oil spill resulting from the Deepwater Horizon blow out.

  6. Stochastic Plume Simulations for the Fukushima Accident and the Deep Water Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Coelho, E.; Peggion, G.; Rowley, C.; Hogan, P.

    2012-04-01

    The Fukushima Dai-ichi power plant suffered damage leading to radioactive contamination of coastal waters. Major issues in characterizing the extent of the affected waters were a poor knowledge of the radiation released to the coastal waters and the rather complex coastal dynamics of the region, not deterministically captured by the available prediction systems. Equivalently, during the Gulf of Mexico Deep Water Horizon oil platform accident in April 2010, significant amounts of oil and gas were released from the ocean floor. For this case, issues in mapping and predicting the extent of the affected waters in real-time were a poor knowledge of the actual amounts of oil reaching the surface and the fact that coastal dynamics over the region were not deterministically captured by the available prediction systems. To assess the ocean regions and times that were most likely affected by these accidents while capturing the above sources of uncertainty, ensembles of the Navy Coastal Ocean Model (NCOM) were configured over the two regions (NE Japan and Northern Gulf of Mexico). For the Fukushima case tracers were released on each ensemble member; their locations at each instant provided reference positions of water volumes where the signature of water released from the plant could be found. For the Deep Water Horizon oil spill case each ensemble member was coupled with a diffusion-advection solution to estimate possible scenarios of oil concentrations using perturbed estimates of the released amounts as the source terms at the surface. Stochastic plumes were then defined using a Risk Assessment Code (RAC) analysis that associates a number from 1 to 5 to each grid point, determined by the likelihood of having tracer particle within short ranges (for the Fukushima case), hence defining the high risk areas and those recommended for monitoring. For the Oil Spill case the RAC codes were determined by the likelihood of reaching oil concentrations as defined in the Bonn Agreement

  7. Computer simulation of the probability that endangered whales will interact with oil spills, Final report

    SciTech Connect

    Reed, M.; Jayko, K.; Bowles, A.; Anderson, E.; Leatherwood, S.

    1986-10-01

    A numerical model system was developed to assess quantitatively the probability that endangered bowhead and gray whales will encounter spilled oil in Alaskan waters. Bowhead and gray whale migration diving-surfacing models, and an oil-spill-trajectory model comprise the system. The migration models were developed from conceptual considerations, then calibrated with and tested against observations. The distribution of animals is represented in space and time by discrete points, each of which may represent one or more whales. The movement of a whale point is governed by a random-walk algorithm which stochastically follows a migratory pathway.

  8. Computer Simulation of Stress-Strain State of Oil Gathering Pipeline Designed for Ugut Field

    NASA Astrophysics Data System (ADS)

    Burkov, P. V.; Burkova, S. P.; Samigullin, V. D.

    2016-04-01

    The paper presents the stress and strain state modeling of infield pipeline in Ugut oil field. The finite element models of the stress field distribution in the pipeline wall are presented in this paper. The attention is paid to the pipeline reliability under stress conditions induced by the internal pressure and external compressive or tensile loads.

  9. Effective bioremediation strategy for rapid in situ cleanup of anoxic marine sediments in mesocosm oil spill simulation

    PubMed Central

    Genovese, Maria; Crisafi, Francesca; Denaro, Renata; Cappello, Simone; Russo, Daniela; Calogero, Rosario; Santisi, Santina; Catalfamo, Maurizio; Modica, Alfonso; Smedile, Francesco; Genovese, Lucrezia; Golyshin, Peter N.; Giuliano, Laura; Yakimov, Michail M.

    2014-01-01

    The purpose of present study was the simulation of an oil spill accompanied by burial of significant amount of petroleum hydrocarbons (PHs) in coastal sediments. Approximately 1000 kg of sediments collected in Messina harbor were spiked with Bunker C furnace fuel oil (6500 ppm). The rapid consumption of oxygen by aerobic heterotrophs created highly reduced conditions in the sediments with subsequent recession of biodegradation rates. As follows, after 3 months of ageing, the anaerobic sediments did not exhibit any significant levels of biodegradation and more than 80% of added Bunker C fuel oil remained buried. Anaerobic microbial community exhibited a strong enrichment in sulfate-reducing PHs-degrading and PHs-associated Deltaproteobacteria. As an effective bioremediation strategy to clean up these contaminated sediments, we applied a Modular Slurry System (MSS) allowing the containment of sediments and their physical–chemical treatment, e.g., aeration. Aeration for 3 months has increased the removal of main PHs contaminants up to 98%. As revealed by CARD-FISH, qPCR, and 16S rRNA gene clone library analyses, addition of Bunker C fuel oil initially affected the activity of autochthonous aerobic obligate marine hydrocarbonoclastic bacteria (OMHCB), and after 1 month more than the third of microbial population was represented by Alcanivorax-, Cycloclasticus-, and Marinobacter-related organisms. In the end of the experiment, the microbial community composition has returned to a status typically observed in pristine marine ecosystems with no detectable OMHCB present. Eco-toxicological bioassay revealed that the toxicity of sediments after treatment was substantially decreased. Thus, our studies demonstrated that petroleum-contaminated anaerobic marine sediments could efficiently be cleaned through an in situ oxygenation which stimulates their self-cleaning potential due to reawakening of allochtonous aerobic OMHCB. PMID:24782850

  10. The oil spill model OILTRANS and its application to the Celtic Sea.

    PubMed

    Berry, Alan; Dabrowski, Tomasz; Lyons, Kieran

    2012-11-01

    This paper describes details of an oil spill model, OILTRANS, developed by the authors. The model is an off-line particle-transport model coupled to the most up to date operational met-ocean model forecasts. Formulations for the dominant oil fate processes of spreading, advection, diffusion, evaporation, emulsification and dispersion have been encoded, providing the model with the ability to accurately predict the horizontal movement of surface oil slick, the vertical entrainment of oil into the water column and the mass balance of spilled oil. The application of the OILTRANS model to an accidental release during a ship-to-ship fuel transfer in the Celtic Sea in February 2009 is presented to validate the system. Comparisons with aerial observations of the oil slick at the time of the incident, and subsequent model simulations, indicate that the OILTRANS model is capable of accurately predicting the transport and fate of the oil slick.

  11. Terahertz-dependent identification of simulated hole shapes in oil-gas reservoirs

    NASA Astrophysics Data System (ADS)

    Bao, Ri-Ma; Zhan, Hong-Lei; Miao, Xin-Yang; Zhao, Kun; Feng, Cheng-Jing; Dong, Chen; Li, Yi-Zhang; Xiao, Li-Zhi

    2016-10-01

    Detecting holes in oil-gas reservoirs is vital to the evaluation of reservoir potential. The main objective of this study is to demonstrate the feasibility of identifying general micro-hole shapes, including triangular, circular, and square shapes, in oil-gas reservoirs by adopting terahertz time-domain spectroscopy (THz-TDS). We evaluate the THz absorption responses of punched silicon (Si) wafers having micro-holes with sizes of 20 μm-500 μm. Principal component analysis (PCA) is used to establish a model between THz absorbance and hole shapes. The positions of samples in three-dimensional spaces for three principal components are used to determine the differences among diverse hole shapes and the homogeneity of similar shapes. In addition, a new Si wafer with the unknown hole shapes, including triangular, circular, and square, can be qualitatively identified by combining THz-TDS and PCA. Therefore, the combination of THz-TDS with mathematical statistical methods can serve as an effective approach to the rapid identification of micro-hole shapes in oil-gas reservoirs. Project supported by the National Natural Science Foundation of China (Grant No. 61405259), the National Basic Research Program of China (Grant No. 2014CB744302), and the Specially Founded Program on National Key Scientific Instruments and Equipment Development, China (Grant No. 2012YQ140005).

  12. Simulation of the migration and transformation of petroleum pollutants in the soils of the Loess plateau: a case study in the Maling oil field of northwestern China.

    PubMed

    Pan, Feng; Ma, Jinzhu; Wang, Yunquan; Zhang, Yali; Chen, Lihua; Edmunds, W Mike

    2013-10-01

    We developed a coupled water-oil simulation model to simulate the migration and transformation of petroleum-derived contaminants in the soil of the Xifeng oil field. To do so, we used the HYDRUS-2D model, which simulates the diffusion, adsorption or desorption, and microbial degradation of petroleum-derived hydrocarbons in the soil-water system. The saturated soil hydraulic conductivity of petroleum-derived pollutants was 0.05 cm day(-1), which is about 1 to 2 % of the soil moisture permeability coefficient. Our numerical simulation results show that spilled crude oil was mainly concentrated in the surface horizons of the soil. The organic pollutant concentration tended to be highest nearest to the pollution source. The pollutant migration was generally concentrated within the top 20 to 30 cm of the soil, with the maximum concentration in the top 5 cm of the soil. With passing time, the pollutant accumulation increased and the adsorption and degradation functions reached a dynamic balance with the input rate at depths greater than 30 cm below the soil surface. The oil-derived pollutants totaled 50 to 100 mg kg(-1) under the dynamic balance condition, which occurred after 20 to 30 years. The petroleum-derived pollutant concentration in the loess soil was inversely correlated with the horizontal distance from the oil well, and the concentration decreased greatly at a distance greater than 40 m from the well.

  13. Evaluation of autochthonous bioaugmentation and biostimulation during microcosm-simulated oil spills.

    PubMed

    Nikolopoulou, M; Pasadakis, N; Kalogerakis, N

    2013-07-15

    Oil spills are treated as a widespread problem that poses a great threat to any ecosystem. Following first response actions, bioremediation has emerged as the best strategy for combating oil spills and can be enhanced by the following two complementary approaches: bioaugmentation and biostimulation. Bioaugmentation is one of the most controversial issues of bioremediation. Studies that compare the relative performance of bioaugmentation and biostimulation suggest that nutrient addition alone has a greater effect on oil biodegradation than the addition of microbial products because the survival and degradation ability of microbes introduced to a contaminated site are highly dependent on environmental conditions. Microbial populations grown in rich media under laboratory conditions become stressed when exposed to field conditions in which nutrient concentrations are substantially lower. There is increasing evidence that the best approach to overcoming these barriers is the use of microorganisms from the polluted area, an approach proposed as autochthonous bioaugmentation (ABA) and defined as a bioaugmentation technology that exclusively uses microorganisms indigenous to the sites (soil, sand, and water) slated for decontamination. In this work, we examined the effectiveness of strategies combining autochthonous bioaugmentation with biostimulation for successful remediation of polluted marine environments. Seawater was collected from a pristine area (Agios Onoufrios Beach, Chania) and was placed in a bioreactor with 1% v/v crude oil to facilitate the adaptation of the indigenous microorganism population. The pre-adapted consortium and the indigenous population were tested in combination with inorganic or lipophilic nutrients in the presence (or absence) of biosurfactants (rhamnolipids) during 90-day long experiments. Chemical analysis (gas chromatography-mass spectrometry) of petroleum hydrocarbons confirmed the results of previous work demonstrating that the

  14. Simulation of the fluorescence evolution of “live” oils from kerogens in a diamond anvil cell: Application to inclusion oils in terms of maturity and source

    NASA Astrophysics Data System (ADS)

    Chang, Ying-Ju; Huang, Wuu-Liang

    2008-08-01

    The evolution of fluorescence has been measured for "live" oils generated from 14 oil-prone kerogens or coals from varying depositional environments during closed system pyrolysis in a diamond anvil cell at three heating rates (3, 8, and 25 °C/min), and temperatures up to 600 °C. The measured fluorescence intensities of the samples, employing using violet excitation at 405 nm, increases significantly during maturation intervals within the oil window, while the fluorescence spectra of oils generated from all studied kerogens exhibit progressive blue-shift of peak wavelengths ( λmax) and red/green quotients ( I650/ I500) upon increasing maturity. The observed trend is consistent with a maturity dependence of the spectral shift, which is widely recognized in natural hydrocarbon inclusions and crude oils using ultraviolet (UV) excitation (365 nm). The data presented herein suggest that the λmax of spectra for inclusion oils shift in similar direction despite differences in composition or source kerogen. This implies that the reverse or anomalous trends reported for inclusion oils in nature may be attributed to other processes, which significantly alters the fluorescence properties of oils subsequent to their generation. Oils with the similar color ( λmax or I650/ I500) can be derived from diverse kerogens with maturities that vary by ±0.3% Ro, suggesting that the fluorescent colors of crude and inclusion oils are both maturity- and source-dependent, and therefore cannot be used as universal maturity indicators. In addition, the blue-shifts observed for cumulative oils generated from all kerogens approaches similar minima λmax values around the green-yellow wavelength (564 nm) and at I650/ I500 values around 0.6, at maturities close to the middle or late stage of oil generation. This suggests that most late-stage cumulative oils will exhibit similar colors. Oils generated during late-stage maturity intervals, however, can exhibit colors with shorter wavelengths.

  15. Accurate Drawbead Modeling in Stamping Simulations

    NASA Astrophysics Data System (ADS)

    Sester, M.; Burchitz, I.; Saenz de Argandona, E.; Estalayo, F.; Carleer, B.

    2016-08-01

    An adaptive line bead model that continually updates according to the changing conditions during the forming process has been developed. In these calculations, the adaptive line bead's geometry is treated as a 3D object where relevant phenomena like hardening curve, yield surface, through thickness stress effects and contact description are incorporated. The effectiveness of the adaptive drawbead model will be illustrated by an industrial example.

  16. Bioremediation (bioaugmentation/biostimulation) trials of oil polluted seawater: a mesocosm simulation study.

    PubMed

    Hassanshahian, Mehdi; Emtiazi, Giti; Caruso, Gabriella; Cappello, Simone

    2014-04-01

    Bioaugmentation (amendment with selected bacterial strains) and/or biostimulation (nutrients addition and/or air supply) are relatively new fields in environmental microbiology for preventing pollution and cleanup contamination. In this study, the efficiency of application of bioaugmentation/biostimulation treatments, for recovery of crude oil-polluted seawater, was evaluated. Three different series of experiments were performed in a "Mesocosm Facility" (10.000 L). Natural seawater was artificially polluted with crude oil (1000 ppm) and was amended with inorganic nutrients (Mesocosm 1, M1), inorganic nutrient and an inoculum of Alcanivorax borkumensis SK2(T) (Mesocosm 2, M2) and inorganic nutrient and an inoculum of A. borkumensis SK2(T) and Thalassolituus oleivorans MIL-1(T) (Mesocosm 3, M3), respectively. During the experimental period (20 days) bacterial abundance (DAPI count), culturable heterotrophic bacteria (CFU count), MPN, microbial metabolic activity [Biochemical Oxygen Demand and enzymatic activity (leucine aminopeptidase LAP, β-glucosidase BG, alkaline phosphatase AP)] and quali-, quantitative analysis of the composition of total extracted and resolved hydrocarbons and their derivates (TERHCs) were carried out. The microbiological and physiological analysis of marine microbial community found during the three different biostimulation and bioaugmentation assays performed in mesocosms show that the load of crude oil increases total microbial abundance, inhibits the activity of some enzymes such as LAP while stimulates both AP and BG activities. The biodegradation results show that bioaugmentation with A. borkumensis SK2(T) alone is able to produce the highest percentage of degradation (95%) in comparison with the biostimulation treatment (80%) and bioaugmentation using an Alcanivorax-Thalassolituus bacterial consortium (70%). This result highlights the reduced biodegradation capability of the consortium used in this study, suggesting an unfavourable

  17. Degradation and aquatic toxicity of naphthenic acids in oil sands process-affected waters using simulated wetlands.

    PubMed

    Toor, Navdeep S; Franz, Eric D; Fedorak, Phillip M; MacKinnon, Michael D; Liber, Karsten

    2013-01-01

    Oil sands process-affected waters (OSPWs) produced during the extraction of bitumen at the Athabasca Oil Sands (AOS) located in northeastern Alberta, Canada, are toxic to many aquatic organisms. Much of this toxicity is related to a group of dissolved organic acids known as naphthenic acids (NAs). Naphthenic acids are a natural component of bitumen and are released into process water during the separation of bitumen from the oil sand ore by a caustic hot water extraction process. Using laboratory microcosms as an analogue of a proposed constructed wetland reclamation strategy for OSPW, we evaluated the effectiveness of these microcosms in degrading NAs and reducing the aquatic toxicity of OSPW over a 52-week test period. Experimental manipulations included two sources of OSPW (one from Syncrude Canada Ltd. and one from Suncor Energy Inc.), two different hydraulic retention times (HRTs; 40 and 400 d), and increased nutrient availability (added nitrate and phosphate). Microcosms with a longer HRT (for both OSPWs) showed higher reductions in total NAs concentrations (64-74% NAs reduction, p<0.05) over the test period, while nutrient enrichment appeared to have little effect. A 96 h static acute rainbow trout (Oncorhynchus mykiss) bioassay showed that the initial acute toxicity of Syncrude OSPW (LC50=67% v/v) was reduced (LC50>100% v/v) independent of HRT. However, EC20s from separate Microtox® bioassays were relatively unchanged when comparing the input and microcosm waters at both HRTs over the 52-week study period (p>0.05), indicating that some sub-lethal toxicity persisted under these experimental conditions. The present study demonstrated that given sufficiently long HRTs, simulated wetland microcosms containing OSPW significantly reduced total NAs concentrations and acute toxicity, but left behind a persistent component of the NAs mixture that appeared to be associated with residual chronic toxicity.

  18. Forecasting skill assessment of an oil spill simulation system in the NE Aegean and atmospheric forcing perturbation experiments

    NASA Astrophysics Data System (ADS)

    Kailas, Marios; Chrysagi, Eyrydice; Sofianos, Sarantis

    2016-04-01

    In the present study, the predictive skill of an oil spill simulation system implemented in the Northern Aegean Sea was evaluated using field observations from surface drifters, provided in the framework of the TOSCA project. The system produces satisfactory results as in most cases the forecasting error is quite small, allowing the operational use of the forecast. In order to examine the sensitivity of the forecast to atmospheric forcing, additional simulations with perturbed atmospheric conditions were performed, using a time-shifting technique. In most experiments the differences between the simulations are relatively small, most likely due to slow oceanic response to variations in the wind fields. From the individual simulations an ensemble forecast was created, the results of which were also compared with the observations. The results suggest that by applying this method a safer forecast can be provided, especially regarding cases for which the wind-driven circulation is predominant. However, in cases where the circulation is characterized by intense velocity gradients (in the NE Aegean this is associated with the thermohaline front created by the Black Sea Water inflow), larger differences are present. They are related to imprecise representation of the location of the front. In these cases, the ensemble method produced no significant improvement since the relatively small differences between the trajectories of the ensemble members indicate that the position of the front in not significantly affected by the wind perturbations, based on the spatio-temporal scales examined. It is concluded that in regions with large spatio-temporal variability, an ensemble forecast produced by simulations generated from perturbed initial conditions could possibly lead to more robust results.

  19. Solubility of Carbon Dioxide in Pentaerythritol Hexanoate: Molecular Dynamics Simulation of a Refrigerant-Lubricant Oil System.

    PubMed

    Sugii, Taisuke; Ishii, Eiji; Müller-Plathe, Florian

    2015-09-17

    We have investigated the solubility and the solvation structure between a refrigerant (carbon dioxide, CO2) and a lubricant oil (pentaerythritol hexanoate, PEC6) by molecular dynamics simulations. First, to investigate the solubility, we calculated the vapor-liquid equilibrium pressure. The chemical potential of the liquid phase and the gas phase were calculated, and the equilibrium state was obtained from the crossing point of these chemical potentials. The equilibrium pressures agreed well with experimental data over a wide range of temperatures and mole fractions of CO2. Second, the solvation structure was also investigated on a molecular scale. We found the following characteristics. First, the tails of the lubricant oil are relatively rigid inside the ester groups but flexible beyond. Second, CO2 molecules barely enter the lubricant core as delimited by the ester groups. Third, the double-bonded oxygen atoms of the ester groups are good sorption sites for CO2. Fourth, only a few CO2 molecules are attached to more than one carbonyl oxygen simultaneously. Finally, there is also significant unspecific sorption of CO2 in the alkane tail region. These results indicate that increasing the size of the rigid lubricant core would probably decrease the solubility, whereas increasing the number of polar groups would increase it. PMID:26287696

  20. Reactive atomistic simulations of shock-induced initiation processes in mixtures of ammonium nitrate and fuel oil

    NASA Astrophysics Data System (ADS)

    Thompson, Aidan P.; Shan, Tzu-Ray

    2014-05-01

    Ammonium nitrate mixed with fuel oil (ANFO) is a commonly used blasting agent. In this paper we investigated the shock properties of pure ammonium nitrate (AN) and two different mixtures of ammonium nitrate and n-dodecane by characterizing their Hugoniot states. We simulated shock compression of pure AN and ANFO mixtures using the Multi-scale Shock Technique, and observed differences in chemical reaction. We also performed a large-scale explicit sub-threshold shock of AN crystal with a 10 nm void filled with 4.4 wt% of n-dodecane. We observed the formation of hotspots and enhanced reactivity at the interface region between AN and n-dodecane molecules.

  1. Using DUSTRAN to Simulate Fog-Oil Dispersion and Its Impacts on Local Insect Populations at Ft. Hood: Final Report

    SciTech Connect

    Rishel, Jeremy P.; Chapman, Elaine G.; Rutz, Frederick C.; Allwine, K Jerry

    2006-12-29

    Smokes and obscurants (S&O) are important screening agents used during military training exercises on many military installations. Although the use of S&O is subject to environmental laws, the fate and effects of S&O on natural habitats are not well documented. One particular concern is the impact S&O may have on local insect populations, which can be important components of terrestrial food chains of endangered species. Fog-oil (FO) is an S&O that is of particular concern. An important part of assessing potential ecosystem impacts is the ability to predict downwind FO concentrations. This report documents the use of the comprehensive atmospheric dispersion modeling system DUST TRANsport (DUSTRAN) to simulate the downwind transport and diffusion of a hypothetical FO release on the U.S. Army installation at Ft. Hood, TX.

  2. Effects of clove oil-phospholipid mixtures on rheology of gum tragacanth - possible application for surfactant action on mucus gel simulants.

    PubMed

    Banerjee, R; Puniyani, R R

    2000-01-01

    The present study evaluates the effectiveness of specialised biomaterials consisting of clove oil- phospholipid mixtures as possible substitute surfactants in diseases of altered mucus viscosity by studying their effect on the viscosity of mucus gel simulants in vitro. Test surfactants consisting of phospholipid-clove oil mixtures in the ratio of 1 part of oil to 9 parts of phospholipid were prepared. The phospholipids used were dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) and binary mixtures of PC: PE and PC: PG in the ratio of 2 parts of PC to 3 parts of PE or PG. The effects of the phospholipid-clove oil mixtures on the viscosity of mucus gel simulant (MGS: a polymeric gel consisting predominantly of gum tragacanth and simulating respiratory mucus), was studied by application of steady shear rates ranging from 0.512 to 51.2/s in a concentric cylinder viscometer at 37 degrees C. The change in MGS viscosity, after incubation with surfactants, was found to have a non-Newtonian character and to follow the power law model with R2 values >0.8. The addition of clove oil-phospholipid mixtures caused a decrease in the MGS viscosity when compared with the effect of the phospholipid alone at low shear rates in case of PC, PG and PCPG. The combination of PC : PG with clove oil caused ratios of change in MGS viscosity < 1 i.e., caused a decrease in the MGS viscosity. PC: PG with clove oil was capable of lowering MGS viscosity and should be further researched as possible therapies for diseases of altered mucus rheology.

  3. Effects of clove oil-phospholipid mixtures on rheology of gum tragacanth - possible application for surfactant action on mucus gel simulants.

    PubMed

    Banerjee, R; Puniyani, R R

    2000-01-01

    The present study evaluates the effectiveness of specialised biomaterials consisting of clove oil- phospholipid mixtures as possible substitute surfactants in diseases of altered mucus viscosity by studying their effect on the viscosity of mucus gel simulants in vitro. Test surfactants consisting of phospholipid-clove oil mixtures in the ratio of 1 part of oil to 9 parts of phospholipid were prepared. The phospholipids used were dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) and binary mixtures of PC: PE and PC: PG in the ratio of 2 parts of PC to 3 parts of PE or PG. The effects of the phospholipid-clove oil mixtures on the viscosity of mucus gel simulant (MGS: a polymeric gel consisting predominantly of gum tragacanth and simulating respiratory mucus), was studied by application of steady shear rates ranging from 0.512 to 51.2/s in a concentric cylinder viscometer at 37 degrees C. The change in MGS viscosity, after incubation with surfactants, was found to have a non-Newtonian character and to follow the power law model with R2 values >0.8. The addition of clove oil-phospholipid mixtures caused a decrease in the MGS viscosity when compared with the effect of the phospholipid alone at low shear rates in case of PC, PG and PCPG. The combination of PC : PG with clove oil caused ratios of change in MGS viscosity < 1 i.e., caused a decrease in the MGS viscosity. PC: PG with clove oil was capable of lowering MGS viscosity and should be further researched as possible therapies for diseases of altered mucus rheology. PMID:11202146

  4. Edible oil structures at low and intermediate concentrations. I. Modeling, computer simulation, and predictions for X ray scattering

    NASA Astrophysics Data System (ADS)

    Pink, David A.; Quinn, Bonnie; Peyronel, Fernanda; Marangoni, Alejandro G.

    2013-12-01

    Triacylglycerols (TAGs) are biologically important molecules which form the recently discovered highly anisotropic crystalline nanoplatelets (CNPs) and, ultimately, the large-scale fat crystal networks in edible oils. Identifying the hierarchies of these networks and how they spontaneously self-assemble is important to understanding their functionality and oil binding capacity. We have modelled CNPs and studied how they aggregate under the assumption that all CNPs are present before aggregation begins and that their solubility in the liquid oil is very low. We represented CNPs as rigid planar arrays of spheres with diameter ≈50 nm and defined the interaction between spheres in terms of a Hamaker coefficient, A, and a binding energy, VB. We studied three cases: weak binding, |VB|/kBT ≪ 1, physically realistic binding, VB = Vd(R, Δ), so that |VB|/kBT ≈ 1, and Strong binding with |VB|/kBT ≫ 1. We divided the concentration of CNPs, ϕ, with 0≤ϕ= 10-2 (solid fat content) ≤1, into two regions: Low and intermediate concentrations with 0<ϕ<0.25 and high concentrations with 0.25 < ϕ and considered only the first case. We employed Monte Carlo computer simulation to model CNP aggregation and analyzed them using static structure functions, S(q). We found that strong binding cases formed aggregates with fractal dimension, D, 1.7≤D ≤1.8, in accord with diffusion limited cluster-cluster aggregation (DLCA) and weak binding formed aggregates with D =3, indicating a random distribution of CNPs. We found that models with physically realistic intermediate binding energies formed linear multilayer stacks of CNPs (TAGwoods) with fractal dimension D =1 for ϕ =0.06,0.13, and 0.22. TAGwood lengths were greater at lower ϕ than at higher ϕ, where some of the aggregates appeared as thick CNPs. We increased the spatial scale and modelled the TAGwoods as rigid linear arrays of spheres of diameter ≈500 nm, interacting via the attractive van der Waals interaction. We

  5. Control of Microbial Sulfide Production with Biocides and Nitrate in Oil Reservoir Simulating Bioreactors.

    PubMed

    Xue, Yuan; Voordouw, Gerrit

    2015-01-01

    Oil reservoir souring by the microbial reduction of sulfate to sulfide is unwanted, because it enhances corrosion of metal infrastructure used for oil production and processing. Reservoir souring can be prevented or remediated by the injection of nitrate or biocides, although injection of biocides into reservoirs is not commonly done. Whether combined application of these agents may give synergistic reservoir souring control is unknown. In order to address this we have used up-flow sand-packed bioreactors injected with 2 mM sulfate and volatile fatty acids (VFA, 3 mM each of acetate, propionate and butyrate) at a flow rate of 3 or 6 pore volumes (PV) per day. Pulsed injection of the biocides glutaraldehyde (Glut), benzalkonium chloride (BAC) and cocodiamine was used to control souring. Souring control was determined as the recovery time (RT) needed to re-establish an aqueous sulfide concentration of 0.8-1 mM (of the 1.7-2 mM before the pulse). Pulses were either for a long time (120 h) at low concentration (long-low) or for a short time (1 h) at high concentration (short-high). The short-high strategy gave better souring control with Glut, whereas the long-low strategy was better with cocodiamine. Continuous injection of 2 mM nitrate alone was not effective, because 3 mM VFA can fully reduce both 2 mM nitrate to nitrite and N2 and, subsequently, 2 mM sulfate to sulfide. No synergy was observed for short-high pulsed biocides and continuously injected nitrate. However, use of continuous nitrate and long-low pulsed biocide gave synergistic souring control with BAC and Glut, as indicated by increased RTs in the presence, as compared to the absence of nitrate. Increased production of nitrite, which increases the effectiveness of souring control by biocides, is the most likely cause for this synergy. PMID:26696994

  6. Control of Microbial Sulfide Production with Biocides and Nitrate in Oil Reservoir Simulating Bioreactors

    PubMed Central

    Xue, Yuan; Voordouw, Gerrit

    2015-01-01

    Oil reservoir souring by the microbial reduction of sulfate to sulfide is unwanted, because it enhances corrosion of metal infrastructure used for oil production and processing. Reservoir souring can be prevented or remediated by the injection of nitrate or biocides, although injection of biocides into reservoirs is not commonly done. Whether combined application of these agents may give synergistic reservoir souring control is unknown. In order to address this we have used up-flow sand-packed bioreactors injected with 2 mM sulfate and volatile fatty acids (VFA, 3 mM each of acetate, propionate and butyrate) at a flow rate of 3 or 6 pore volumes (PV) per day. Pulsed injection of the biocides glutaraldehyde (Glut), benzalkonium chloride (BAC) and cocodiamine was used to control souring. Souring control was determined as the recovery time (RT) needed to re-establish an aqueous sulfide concentration of 0.8–1 mM (of the 1.7–2 mM before the pulse). Pulses were either for a long time (120 h) at low concentration (long-low) or for a short time (1 h) at high concentration (short-high). The short-high strategy gave better souring control with Glut, whereas the long-low strategy was better with cocodiamine. Continuous injection of 2 mM nitrate alone was not effective, because 3 mM VFA can fully reduce both 2 mM nitrate to nitrite and N2 and, subsequently, 2 mM sulfate to sulfide. No synergy was observed for short-high pulsed biocides and continuously injected nitrate. However, use of continuous nitrate and long-low pulsed biocide gave synergistic souring control with BAC and Glut, as indicated by increased RTs in the presence, as compared to the absence of nitrate. Increased production of nitrite, which increases the effectiveness of souring control by biocides, is the most likely cause for this synergy. PMID:26696994

  7. Accurate monotone cubic interpolation

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1991-01-01

    Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.

  8. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  9. The Obtaining of Oil from an Oil Reservoir.

    ERIC Educational Resources Information Center

    Dawe, R. A.

    1979-01-01

    Discusses the mechanics of how an actual oil reservoir works and provides some technical background in physics. An experiment which simulates an oil reservoir and demonstrates quantitatively all the basic concepts of oil reservoir rock properties is also presented. (HM)

  10. Assessing the bioavailability of polyphenols and antioxidant properties of extra virgin argan oil by simulated digestion and Caco-2 cell assays. Comparative study with extra virgin olive oil.

    PubMed

    Seiquer, Isabel; Rueda, Ascensión; Olalla, Manuel; Cabrera-Vique, Carmen

    2015-12-01

    Argan oil is becoming increasingly popular in the edible-oil market as a luxury food with healthy properties. This paper analyzes (i) the bioavailability of the polyphenol content and antioxidant properties of extra virgin argan oil (EVA) by the combination of in vitro digestion and absorption across Caco-2 cells and (ii) the protective role of the oil bioaccessible fraction (BF) against induced oxidative stress. Results were compared with those obtained with extra virgin olive oil (EVO). Higher values of polyphenols and antioxidant activity were observed in the BF obtained after the in vitro digestion of oils compared with the initial chemical extracts; the increase was higher for EVA but absolute BF values were lower than EVO. Bioaccessible polyphenols from EVA were absorbed by Caco-2 cells in higher proportions than from EVO, and minor differences were observed for antioxidant activity. Preincubation of cell cultures with BF from both oils significantly protected against oxidation, limiting cell damage and reducing reactive oxygen species generation.

  11. EFFECT OF AMOUNT OF CRUDE OIL ON EXTENT OF ITS BIODEGRADATION IN OPEN WATER- AND SANDY BEACH-LABORATORY SIMULATIONS

    EPA Science Inventory

    Bioremediation of marine oil spills, a technology using hydrocarbon-degrading and emulsifying capabilities of microorganisms, has many unexplored limitations, and among them is degree of environmental oil contamination. We examined the biodegradation of varying amounts of artifi...

  12. Efficacy of UV-Pit-light traps for discerning micro-habitat-specific beetle and ant species related with different oil palm age stands and tropical annual seasons for accurate ecology and diversity interpretations

    NASA Astrophysics Data System (ADS)

    Ahmad Bukhary, A. K.; Ruslan, M. Y.; Mohd. Fauzi, M. M.; Nicholas, S.; Muhamad Fahmi, M. H.; Izfa Riza, H.; Idris, A. B.

    2015-09-01

    A newly innovated and efficient UV-Pit-light Trap is described and the results of the experiments on its efficacy that were carried out within different oil palm age stands of the year 2013 were evaluated and compared with previous study year of 2010, with out the implementation of the UV-Pit-light Trap. In 2013 the UV-Pit-light Traps, the Malaise Traps, and the Pit-fall Traps were employed, while in 2010, the conventional canopy-height UV-Light Traps, Malaise Traps, and the Pit-fall Traps were employed. The UV-Pit-light traps caught more beetle and ant families, morpho-species, and individuals per species compared with the passive Pit-fall traps. The UV-Pit-light Trap targets different subsets of the oil palm beetles and ants' communities, specifying on epigaeic-related micro-habitats, with different oil palm age stands have different compositions of micro-habitats. The UV-Pit-light Traps have the dual quality for satisfying both the biological and statistical data requirements and evaluations. There were no significant difference between the UV-Pit-light Traps and the passive Pit-fall Traps, while the trapping difference with the Malaise traps for different seasons of the year 2013. The UV-Pit-light Traps and the Malaise Traps were complementary to each other, detecting the activities of beetles and ants around the epigaeic-related micro-habitats or having active flight activities respectively according to annual seasons. The UV-Pit-light Trap is an oil-palm specific type of passive trapping system, focusing on the insect species dwelling the upper-ground/epigaeic micro-habitats.

  13. Simulation Model Based on Non-Newtonian Fluid Mechanics Applied to the Evaluation of the Embolic Effect of Emulsions of Iodized Oil and Anticancer Drug

    SciTech Connect

    Demachi, Hiroshi; Matsui, Osamu; Abo, Hitoshi; Tatsu, Hiroki

    2000-07-15

    Purpose: To verify the difference in embolic effect between oil-in-water (O-W) and water-in-oil (W-O) emulsions composed of iodized oil and an anticancer drug, epirubicin, using a simulation model based on non-Newtonian fluid mechanics.Methods: Flow curves of pure iodized oil and two types of O-W and W-O emulsions immediately and 1 hr after preparation were examined with a viscometer. Using the yield stress data obtained, we simulated the stagnation of each fluid with steady flow in a rigid tube.Results: The W-O emulsions were observed to stagnate in the thin tube at a low pressure gradient. However, the embolic effect of the W-O emulsions decreased 1 hr after preparation. The O-W emulsions were stable and did not stagnate under the conditions in which the W-O emulsions stagnated.Conclusion: The simulation model showed that the embolic effect of the W-O emulsions was superior to that of the O-W emulsions.

  14. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  15. Quick stimulation of Alcanivorax sp. by bioemulsificant EPS₂₀₀₃ on microcosm oil spill simulation.

    PubMed

    Cappello, Simone; Genovese, Maria; Denaro, Renata; Santisi, Santina; Volta, Anna; Bonsignore, Martina; Mancini, Giuseppe; Giuliano, Laura; Genovese, Lucrezia; Yakimov, Michail M

    2014-01-01

    Oil spill microcosms experiments were carried out to evaluate the effect of bioemulsificant exopolysaccharide (EPS₂₀₀₃) on quick stimulation of hydrocarbonoclastic bacteria. Early hours of oil spill, were stimulated using an experimental seawater microcosm, supplemented with crude oil and EPS₂₀₀₃ (SW+OIL+EPS₂₀₀₃); this system was monitored for 2 days and compared to control microcosm (only oil-polluted seawater, SW+OIL). Determination of bacterial abundance, heterotrophic cultivable and hydrocarbon-degrading bacteria were carried out. Community composition of marine bacterioplankton was determined by 16S rRNA gene clone libraries. Data obtained indicated that bioemulsificant addition stimulated an increase of total bacterial abundance and, in particular, selection of bacteria related to Alcanivorax genus; confirming that EPS₂₀₀₃ could be used for the dispersion of oil slicks and could stimulate the selection of marine hydrocarbon degraders thus increasing bioremediation process.

  16. A sub-canopy structure for simulating oil palm in the Community Land Model (CLM-Palm): phenology, allocation and yield

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Roupsard, O.; Bernoux, M.; Le Maire, G.; Panferov, O.; Kotowska, M. M.; Knohl, A.

    2015-11-01

    In order to quantify the effects of forests to oil palm conversion occurring in the tropics on land-atmosphere carbon, water and energy fluxes, we develop a new perennial crop sub-model CLM-Palm for simulating a palm plant functional type (PFT) within the framework of the Community Land Model (CLM4.5). CLM-Palm is tested here on oil palm only but is meant of generic interest for other palm crops (e.g., coconut). The oil palm has monopodial morphology and sequential phenology of around 40 stacked phytomers, each carrying a large leaf and a fruit bunch, forming a multilayer canopy. A sub-canopy phenological and physiological parameterization is thus introduced so that each phytomer has its own prognostic leaf growth and fruit yield capacity but with shared stem and root components. Phenology and carbon and nitrogen allocation operate on the different phytomers in parallel but at unsynchronized steps, separated by a thermal period. An important phenological phase is identified for the oil palm - the storage growth period of bud and "spear" leaves which are photosynthetically inactive before expansion. Agricultural practices such as transplanting, fertilization and leaf pruning are represented. Parameters introduced for the oil palm were calibrated and validated with field measurements of leaf area index (LAI), yield and net primary production (NPP) from Sumatra, Indonesia. In calibration with a mature oil palm plantation, the cumulative yields from 2005 to 2014 matched notably well between simulation and observation (mean percentage error = 3 %). Simulated inter-annual dynamics of PFT-level and phytomer-level LAI were both within the range of field measurements. Validation from eight independent oil palm sites shows the ability of the model to adequately predict the average leaf growth and fruit yield across sites and sufficiently represent the significant nitrogen- and age-related site-to-site variability in NPP and yield. Results also indicate that seasonal dynamics

  17. Impact of extraneous proteins on the gastrointestinal fate of sunflower seed (Helianthus annuus) oil bodies: a simulated gastrointestinal tract study.

    PubMed

    Makkhun, Sakunkhun; Khosla, Amit; Foster, Tim; McClements, David Julian; Grundy, Myriam M L; Gray, David A

    2015-01-01

    In this study, we examined the physicochemical nature of sunflower seed oil bodies (in the absence and presence of added protein) exposed to gastrointestinal conditions in vitro: crude oil bodies (COB); washed oil bodies (WOB); whey protein isolate-enriched oil bodies (WOB-WPI); and, sodium caseinate enriched-oil bodies (WOB-SC). All oil body emulsions were passed through an in vitro digestion model that mimicked the stomach and duodenal environments, and their physicochemical properties were measured before, during, and after digestion. Oil bodies had a positive charge under gastric conditions because the pH was below the isoelectric point of the adsorbed protein layer, but they had a negative charge under duodenal conditions which was attributed to changes in interfacial composition resulting from adsorption of bile salts. Oil bodies were highly susceptible to flocculation and coalescence in both gastric and duodenal conditions. SDS-PAGE analysis indicated degradation of oleosin proteins (ca. 18-21 kDa) to a greater or lesser extent (dependent on the emulsion) during the gastric phase in all emulsions tested; there is evidence that some oleosin remained intact in the crude oil body preparation during this phase of the digestion process. Measurements of protein displacement from the surface of COBs during direct exposure to bile salts, without inclusion of a gastric phase, indicated the removal of intact oleosin from native oil bodies.

  18. Molecular simulation of hydrophobin adsorption at an oil-water interface.

    PubMed

    Cheung, David L

    2012-06-12

    Hydrophobins are small, amphiphilic proteins expressed by strains of filamentous fungi. They fulfill a number of biological functions, often related to adsorption at hydrophobic interfaces, and have been investigated for a number of applications in materials science and biotechnology. In order to understand the biological function and applications of these proteins, a microscopic picture of the adsorption of these proteins at interfaces is needed. Using molecular dynamics simulations with a chemically detailed coarse-grained potential, the behavior of typical hydrophobins at the water-octane interface is studied. Calculation of the interfacial adsorption strengths indicates that the adsorption is essentially irreversible, with adsorption strengths of the order of 100 k(B)T (comparable to values determined for synthetic nanoparticles but significantly larger than small molecule surfactants and biomolecules). The protein structure at the interface is unchanged at the interface, which is consistent with the biological function of these proteins. Comparison of native proteins with pseudoproteins that consist of uniform particles shows that the surface structure of these proteins has a large effect on the interfacial adsorption strengths, as does the flexibility of the protein. PMID:22591377

  19. Molecular simulation of hydrophobin adsorption at an oil-water interface.

    PubMed

    Cheung, David L

    2012-06-12

    Hydrophobins are small, amphiphilic proteins expressed by strains of filamentous fungi. They fulfill a number of biological functions, often related to adsorption at hydrophobic interfaces, and have been investigated for a number of applications in materials science and biotechnology. In order to understand the biological function and applications of these proteins, a microscopic picture of the adsorption of these proteins at interfaces is needed. Using molecular dynamics simulations with a chemically detailed coarse-grained potential, the behavior of typical hydrophobins at the water-octane interface is studied. Calculation of the interfacial adsorption strengths indicates that the adsorption is essentially irreversible, with adsorption strengths of the order of 100 k(B)T (comparable to values determined for synthetic nanoparticles but significantly larger than small molecule surfactants and biomolecules). The protein structure at the interface is unchanged at the interface, which is consistent with the biological function of these proteins. Comparison of native proteins with pseudoproteins that consist of uniform particles shows that the surface structure of these proteins has a large effect on the interfacial adsorption strengths, as does the flexibility of the protein.

  20. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions. Second quarterly report, January 1, 1992--March 31, 1992

    SciTech Connect

    Turner, J.P.; Hasfurther, V.

    1992-05-04

    The scope of the research program and the continuation is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 {times} 3.0 {times} 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by Rio Blanco Oil Shale Co., Inc. (RBOSC) through a separate cooperative agreement with the University of Wyoming (UW) to carry out this study. Three of the lysimeters were established at the RBOSC Tract C-a in the Piceance Basin of Colorado. Two lysimeters were established in the Environmental Simulation Laboratory (ESL) at UW. The ESL was specifically designed and constructed so that a large range of climatic conditions could be physically applied to the processed oil shale which was filled in the lysimeter cells.

  1. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions. Annual report, October 1991--September 1992

    SciTech Connect

    Turner, J.P.; Reeves, T.L.; Skinner, Q.D.; Hasfurther, V.

    1992-11-01

    The scope of the original research program and of its continuation is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large-scale testing sufficient to describe commercial-scale embankment behavior. The large-scale testing was accomplished by constructing five lysimeters, each 7.3{times}3.0{times}3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process (Schmalfield 1975). Approximately 400 tons of Lurgi processed oil shale waste was provided by Rio Blanco Oil Shale Co., Inc. to carry out this study. Three of the lysimeters were established at the RBOSC Tract C-a in the Piceance Basin near Rifle, Colorado. Two lysimeters were established in the Environmental Simulation Laboratory (ESL) at UW. The ESL was specifically designed and constructed so that a large range of climatic conditions could be physically applied to the processed oil shale which was placed in the lysimeter cells. This report discusses and summarizes results from scientific efforts conducted between October 1991 and September 1992 for Fiscal Year 1992.

  2. Accurate Optical Reference Catalogs

    NASA Astrophysics Data System (ADS)

    Zacharias, N.

    2006-08-01

    Current and near future all-sky astrometric catalogs on the ICRF are reviewed with the emphasis on reference star data at optical wavelengths for user applications. The standard error of a Hipparcos Catalogue star position is now about 15 mas per coordinate. For the Tycho-2 data it is typically 20 to 100 mas, depending on magnitude. The USNO CCD Astrograph Catalog (UCAC) observing program was completed in 2004 and reductions toward the final UCAC3 release are in progress. This all-sky reference catalogue will have positional errors of 15 to 70 mas for stars in the 10 to 16 mag range, with a high degree of completeness. Proper motions for the about 60 million UCAC stars will be derived by combining UCAC astrometry with available early epoch data, including yet unpublished scans of the complete set of AGK2, Hamburg Zone astrograph and USNO Black Birch programs. Accurate positional and proper motion data are combined in the Naval Observatory Merged Astrometric Dataset (NOMAD) which includes Hipparcos, Tycho-2, UCAC2, USNO-B1, NPM+SPM plate scan data for astrometry, and is supplemented by multi-band optical photometry as well as 2MASS near infrared photometry. The Milli-Arcsecond Pathfinder Survey (MAPS) mission is currently being planned at USNO. This is a micro-satellite to obtain 1 mas positions, parallaxes, and 1 mas/yr proper motions for all bright stars down to about 15th magnitude. This program will be supplemented by a ground-based program to reach 18th magnitude on the 5 mas level.

  3. Removal by sorption and in situ biodegradation of oil spills limits damage to marine biota: a laboratory simulation.

    PubMed

    Suni, Sonja; Koskinen, Kaisa; Kauppi, Sari; Hannula, Emilia; Ryynänen, Tuukka; Aalto, Annika; Jäänheimo, Jenni; Ikävalko, Johanna; Romantschuk, Martin

    2007-04-01

    This study examined the efficiency of cotton grass fibers in removing diesel oil from the surface of water in conditions prevailing in the Baltic Sea. The effect of low temperature, salinity, and bacterial amendments were tested in laboratory-scale set-ups, whereas 600-L mesocosms filled with Baltic Sea water were used for testing the effects of diesel oil and rapid removal of the oil on microorganisms, phytoplankton, and mussels. Cotton grass proved to be an excellent sorbent for diesel oil from the water surface at a low temperature. Inoculation with diesel-enriched microorganisms enhanced degradation of oil significantly in laboratory-scale experiments. In mesocosm experiments, the addition of diesel oil (0.66 mg L(-1), 0.533 L m(-2)) to the basins resulted in higher microbial density than in all other basins, including inoculated ones, suggesting that the Baltic Sea contains indigenous hydrocarbon degraders. The removal of oil with cotton grass significantly improved the survival of mussels in the mesocosm tests: 100% mortality in diesel basins versus 0% mortality in basins with cotton grass, respectively. However, the surviving mussels suffered from histopathological changes such as inflammatory responses, degenerations, and cell death. The observed rescuing effect was observable even when the cotton grass-bound oil was left in the water. The results underline the importance of rapid action in limiting damage caused by oil spills.

  4. Method of operating an oil shale kiln

    DOEpatents

    Reeves, Adam A.

    1978-05-23

    Continuously determining the bulk density of raw and retorted oil shale, the specific gravity of the raw oil shale and the richness of the raw oil shale provides accurate means to control process variables of the retorting of oil shale, predicting oil production, determining mining strategy, and aids in controlling shale placement in the kiln for the retorting.

  5. Surface dynamics of crude and weathered oil in the presence of dispersants: Laboratory experiment and numerical simulation

    NASA Astrophysics Data System (ADS)

    Soloviev, Alexander V.; Haus, Brian. K.; McGauley, Michael G.; Dean, Cayla W.; Ortiz-Suslow, David G.; Laxague, Nathan J. M.; Özgökmen, Tamay M.

    2016-05-01

    Marine oil spills can have dire consequences for the environment. Research on their dynamics is important for the well-being of coastal communities and their economies. Propagation of oil spills is a very complex physical-chemical process. As seen during the Deepwater Horizon event in the Gulf of Mexico during 2010, one of the critical problems remaining for prediction of oil transport and dispersion in the marine environment is the small-scale structure and dynamics of surface oil spills. The laboratory experiments conducted in this work were focused on understanding the differences between the dynamics of crude and weathered oil spills and the effect of dispersants. After deposition on the still water surface, a drop of crude oil quickly spread into a thin slick; while at the same time, a drop of machine (proxy for weathered) oil did not show significant evolution. Subsequent application of dispersant to the crude oil slick resulted in a quick contraction or fragmentation of the slick into narrow wedges and tiny drops. Notably, the slick of machine oil did not show significant change in size or topology after spraying dispersant. An advanced multi-phase, volume of fluid computational fluid dynamics model, incorporating capillary forces, was able to explain some of the features observed in the laboratory experiment. As a result of the laboratory and modeling experiments, the new interpretation of the effect of dispersant on the oil dispersion process including capillary effects has been proposed, which is expected to lead to improved oil spill models and response strategies.

  6. Simulating carbon, water and energy fluxes of a rainforest and an oil palm plantation using the Community Land Model (CLM4.5)

    NASA Astrophysics Data System (ADS)

    Fan, Yuanchao; Bernoux, Martial; Roupsard, Olivier; Panferov, Oleg; Le Maire, Guerric; Tölle, Merja; Knohl, Alexander

    2014-05-01

    Deforestation and forest degradation driven by the expansion of oil palm (Elaeis guineensis) plantations has become the major source of GHG emission in Indonesia. Changes of land surface properties (e.g. vegetation composition, soil property, surface albedo) associated with rainforest to oil palm conversion might alter the patterns of land-atmosphere energy, water and carbon cycles and therefore affect local or regional climate. Land surface modeling has been widely used to characterize the two-way interactions between climate and human disturbances on land surface. The Community Land Model (CLM) is a third-generation land model that simulates a wide range of biogeophysical and biogeochemical processes. This project utilizes the land-cover/land-use change (LCLUC) capability of the latest CLM versions 4/4.5 to characterize quantitatively how anthropogenic land surface dynamics in Indonesia affect land-atmosphere carbon, water and energy fluxes. Before simulating land use changes, the first objective is to parameterize and validate the CLM model at local rainforest and oil palm plantation sites through separate point simulations. This entails creation and parameterization of a new plant functional type (PFT) for oil palm, as well as sensitivity analysis and adaptation of model parameters for the rainforest PFTs. CLM modelled fluxes for the selected sites are to be compared with field observations from eddy covariance (EC) flux towers (e.g. a rainforest site in Bariri, Sulawesi; an oil palm site in Jambi, Sumatra). After validation, the project will proceed to parameterize land-use transformation system using remote sensing data and to simulate the impacts of historical LUCs on carbon, water and energy fluxes. Last but not least, the effects of future LUCs in Indonesia on the fluxes and carbon sequestration capacity will be investigated through scenario study. Historical land cover changes, especially oil palm coverage, are retrieved from Landsat or MODIS archival

  7. Unraveling the interactive effects of climate change and oil contamination on laboratory-simulated estuarine benthic communities.

    PubMed

    Coelho, Francisco J R C; Cleary, Daniel F R; Rocha, Rui J M; Calado, Ricardo; Castanheira, José M; Rocha, Sílvia M; Silva, Artur M S; Simões, Mário M Q; Oliveira, Vanessa; Lillebø, Ana I; Almeida, Adelaide; Cunha, Ângela; Lopes, Isabel; Ribeiro, Rui; Moreira-Santos, Matilde; Marques, Catarina R; Costa, Rodrigo; Pereira, Ruth; Gomes, Newton C M

    2015-05-01

    There is growing concern that modifications to the global environment such as ocean acidification and increased ultraviolet radiation may interact with anthropogenic pollutants to adversely affect the future marine environment. Despite this, little is known about the nature of the potential risks posed by such interactions. Here, we performed a multifactorial microcosm experiment to assess the impact of ocean acidification, ultraviolet B (UV-B) radiation and oil hydrocarbon contamination on sediment chemistry, the microbial community (composition and function) and biochemical marker response of selected indicator species. We found that increased ocean acidification and oil contamination in the absence of UV-B will significantly alter bacterial composition by, among other things, greatly reducing the relative abundance of Desulfobacterales, known to be important oil hydrocarbon degraders. Along with changes in bacterial composition, we identified concomitant shifts in the composition of oil hydrocarbons in the sediment and an increase in oxidative stress effects on our indicator species. Interestingly, our study identifies UV-B as a critical component in the interaction between these factors, as its presence alleviates harmful effects caused by the combination of reduced pH and oil pollution. The model system used here shows that the interactive effect of reduced pH and oil contamination can adversely affect the structure and functioning of sediment benthic communities, with the potential to exacerbate the toxicity of oil hydrocarbons in marine ecosystems.

  8. Structural properties of polymer-brush-grafted gold nanoparticles at the oil-water interface: insights from coarse-grained simulations.

    PubMed

    Quan, Xuebo; Peng, ChunWang; Dong, Jiaqi; Zhou, Jian

    2016-04-14

    In this work, the structural properties of amphiphilic polymer-brush-grafted gold nanoparticles (AuNPs) at the oil-water interface were investigated by coarse-grained simulations. The effects of grafting architecture (diblock, mixed and Janus brush-grafted AuNPs) and hydrophilicity of polymer brushes are discussed. Simulation results indicate that functionalized AuNPs present abundant morphologies including typical core-shell, Janus-type, jellyfish-like, etc., in a water or oil-water solvent environment. It is found that hydrophobic/weak hydrophilic polymer-brush-grafted AuNPs have better phase transfer performance, especially for AuNPs modified with hydrophobic chains as outer blocks and weak hydrophilic chains as inner blocks. This kind of AuNP can cross the interface region and move into the oil phase completely. For hydrophobic/strong hydrophilic polymer-brush-grafted AuNPs, they are trapped in the interface region instead of moving into any phase. The mechanism of phase transfer is ascribed to the flexibility and mobility of outer blocks. Besides, we study the desorption energy by PMF analysis. The results demonstrate that Janus brush-grafted AuNPs show the highest interfacial stability and activity, which can be further strengthened by increasing the hydrophilicity of grafted polymer brushes. This work will promote the industrial applications of polymer-brush-grafted NPs such as phase transfer catalysis and Pickering emulsion catalysis. PMID:26954721

  9. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions. Final report, November 1995

    SciTech Connect

    1995-12-31

    A study is described on the hydrological and geotechnical behavior of an oil shale solid waste. The objective was to obtain information which can be used to assess the environmental impacts of oil shale solid waste disposal in the Green River Basin. The spent shale used in this study was combusted by the Lurgi-Ruhrgas process by Rio Blanco Oil Shale Company, Inc. Laboratory bench-scale testing included index properties, such as grain size distribution and Atterberg limits, and tests for engineering properties including hydraulic conductivity and shear strength. Large-scale tests were conducted on model spent shale waste embankments to evaluate hydrological response, including infiltration, runoff, and seepage. Large-scale tests were conducted at a field site in western Colorado and in the Environmental Simulation Laboratory (ESL)at the University of Wyoming. The ESL tests allowed the investigators to control rainfall and temperature, providing information on the hydrological response of spent shale under simulated severe climatic conditions. All experimental methods, materials, facilities, and instrumentation are described in detail, and results are given and discussed. 34 refs.

  10. A NEW GENERATION CHEMICAL FLOODING SIMULATOR

    SciTech Connect

    Gary A. Pope; Kamy Sepehrnoori; Mojdeh Delshad

    2002-09-30

    The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved using state-of-the-art computing and computers. Such a simulator is not currently available to the industry. The goal of this proposed research is to develop a new-generation chemical flooding simulator that is capable of efficiently and accurately simulating oil reservoirs with at least a million gridblocks in less than one day on massively parallel computers. Task 1 is the formulation and development of solution scheme, Task 2 is the implementation of the chemical module, and Task 3 is validation and application.

  11. A NEW GENERATION CHEMICAL FLOODING SIMULATOR

    SciTech Connect

    Gary A. Pope; Kamy Sepehrnoori; Mojdeh Delshad

    2005-01-01

    The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved using state-of-the-art algorithms and computers. Such a simulator is not currently available to the industry. The goal of this proposed research is to develop a new-generation chemical flooding simulator that is capable of efficiently and accurately simulating oil reservoirs with at least a million gridblocks in less than one day on massively parallel computers. Task 1 is the formulation and development of solution scheme, Task 2 is the implementation of the chemical module, and Task 3 is validation and application. In this final report, we will detail our progress on Tasks 1 through 3 of the project.

  12. Ruminal methane inhibition potential of various pure compounds in comparison with garlic oil as determined with a rumen simulation technique (Rusitec).

    PubMed

    Soliva, Carla R; Amelchanka, Sergej L; Duval, Stéphane M; Kreuzer, Michael

    2011-07-01

    Ruminants represent an important source of methane (CH(4)) emissions; therefore, CH(4) mitigation by diet supplementation is a major goal in the current ruminant research. The objective of the present study was to use a rumen simulation technique to evaluate the CH(4)-mitigating potential of pure compounds in comparison with that achieved with garlic oil, a known anti-methanogenic supplement. A basal diet (15 g DM/d) consisting of ryegrass hay, barley and soyabean meal (1:0·7:0·3) was incubated with the following additives: none (negative control); garlic oil (300 mg/l incubation liquid; positive control); allyl isothiocyanate (75 mg/l); lovastatin (150 mg/l); chenodeoxycholic acid (150 mg/l); 3-azido-propionic acid ethyl ester (APEE, 150 mg/l); levulinic acid (300 mg/l); 4-[(pyridin-2-ylmethyl)-amino]-benzoic acid (PABA, 300 mg/l). Fermentation profiles (SCFA, microbial counts and N turnover) and H(2) and CH(4) formation were determined. Garlic oil, allyl isothiocyanate, lovastatin and the synthetic compound APEE decreased the absolute daily CH(4) formation by 91, 59, 42 and 98 %, respectively. The corresponding declines in CH(4) emitted per mmol of SCFA were 87, 32, 40 and 99 %, respectively, compared with the negative control; the total SCFA concentration was unaffected. Garlic oil decreased protozoal numbers and increased bacterial counts, while chenodeoxycholic acid completely defaunated the incubation liquid. In vitro, neutral-detergent fibre disappearance was lower following chenodeoxycholic acid and PABA treatments (- 26 and - 18 %, respectively). In conclusion, garlic oil and APEE were extremely efficient at mitigating CH(4) without noticeably impairing microbial nutrient fermentation. Other promising substances were allyl isothiocyanate and lovastatin. PMID:21554814

  13. Do Shale Pore Throats Have a Threshold Diameter for Oil Storage?

    NASA Astrophysics Data System (ADS)

    Zou, Caineng; Jin, Xu; Zhu, Rukai; Gong, Guangming; Sun, Liang; Dai, Jinxing; Meng, Depeng; Wang, Xiaoqi; Li, Jianming; Wu, Songtao; Liu, Xiaodan; Wu, Juntao; Jiang, Lei

    2015-08-01

    In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries.

  14. Do Shale Pore Throats Have a Threshold Diameter for Oil Storage?

    PubMed Central

    Zou, Caineng; Jin, Xu; Zhu, Rukai; Gong, Guangming; Sun, Liang; Dai, Jinxing; Meng, Depeng; Wang, Xiaoqi; Li, Jianming; Wu, Songtao; Liu, Xiaodan; Wu, Juntao; Jiang, Lei

    2015-01-01

    In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries. PMID:26314637

  15. Abundance quantification by independent component analysis of hyperspectral imagery for oil spill coverage calculation

    NASA Astrophysics Data System (ADS)

    Han, Zhongzhi; Wan, Jianhua; Zhang, Jie; Zhang, Hande

    2016-08-01

    The estimation of oil spill coverage is an important part of monitoring of oil spills at sea. The spatial resolution of images collected by airborne hyper-spectral remote sensing limits both the detection of oil spills and the accuracy of estimates of their size. We consider at-sea oil spills with zonal distribution in this paper and improve the traditional independent component analysis algorithm. For each independent component we added two constraint conditions: non-negativity and constant sum. We use priority weighting by higher-order statistics, and then the spectral angle match method to overcome the order nondeterminacy. By these steps, endmembers can be extracted and abundance quantified simultaneously. To examine the coverage of a real oil spill and correct our estimate, a simulation experiment and a real experiment were designed using the algorithm described above. The result indicated that, for the simulation data, the abundance estimation error is 2.52% and minimum root mean square error of the reconstructed image is 0.030 6. We estimated the oil spill rate and area based on eight hyper-spectral remote sensing images collected by an airborne survey of Shandong Changdao in 2011. The total oil spill area was 0.224 km2, and the oil spill rate was 22.89%. The method we demonstrate in this paper can be used for the automatic monitoring of oil spill coverage rates. It also allows the accurate estimation of the oil spill area.

  16. Effects of simulated weathering on the toxicity of selected crude oils and their components to sea urchin embryos.

    PubMed

    Rial, Diego; Radović, Jagoš R; Bayona, Josep M; Macrae, Kenneth; Thomas, Kevin V; Beiras, Ricardo

    2013-09-15

    Artificial weathering of Angolan crude and a Heavy Fuel Oil (HFO) was performed by evaporation and photooxidation. The aliphatic, aromatic, polar and asphaltene fractions of the fresh and weathered oils were isolated. The toxicity of the water accommodated fraction or an oil/fraction dissolved in DMSO was assessed using the sea urchin embryo test. Photooxidation was observed to decrease the aromatics content and increase polar compounds. A slight reduction in the toxicity of Angolan crude was observed following weathering for the water-accommodated fraction and the extract in DMSO, but no effect was seen for the Heavy Fuel Oil. For aliphatic compounds, the toxicity decreased in the order fresh>evaporated>photooxidated for both Angolan crude and HFO. Weathering slightly increased the toxicity of the aromatic and polar fractions of the oil. The aromatic fractions were responsible for most of the toxicity and the polar compounds were the second most important toxic components, despite having less or similar abundance than the aliphatic fraction. The toxic contribution of the aromatic compounds was higher for the HFO than for the Angolan crude. A decrease in the toxicity of Angolan crude following weathering correlated with a reduction in the toxicity of the aliphatic fraction.

  17. Modeling and simulation of multiphase multicomponent multiphysics porous media flows in the context of chemical enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Dutta, Sourav; Daripa, Prabir; Fluids Team

    2015-11-01

    One of the most important methods of chemical enhanced oil recovery (EOR) involves the use of complex flooding schemes comprising of various layers of fluids mixed with suitable amounts of polymer or surfactant or both. The fluid flow is characterized by the spontaneous formation of complex viscous fingering patterns which is considered detrimental to oil recovery. Here we numerically study the physics of such EOR processes using a modern, hybrid method based on a combination of a discontinuous, multiscale finite element formulation and the method of characteristics. We investigate the effect of different types of heterogeneity on the fingering mechanism of these complex multiphase flows and determine the impact on oil recovery. We also study the effect of surfactants on the dynamics of the flow via reduction of capillary forces and increase in relative permeabilities. Supported by the grant NPRP 08-777-1-141 from the Qatar National Research Fund (a member of The Qatar Foundation).

  18. Foam flooding reservoir simulation algorithm improvement and application

    NASA Astrophysics Data System (ADS)

    Wang, Yining; Wu, Xiaodong; Wang, Ruihe; Lai, Fengpeng; Zhang, Hanhan

    2014-05-01

    As one of the important enhanced oil recovery (EOR) technologies, Foam flooding is being used more and more widely in the oil field development. In order to describe and predict foam flooding, experts at domestic and abroad have established a number of mathematical models of foam flooding (mechanism, empirical and semi-empirical models). Empirical models require less data and apply conveniently, but the accuracy is not enough. The aggregate equilibrium model can describe foam generation, burst and coalescence by mechanism studying, but it is very difficult to accurately describe. The research considers the effects of critical water saturation, critical concentration of foaming agent and critical oil saturation on the sealing ability of foam and considers the effect of oil saturation on the resistance factor for obtaining the gas phase relative permeability and the results were amended by laboratory test, so the accuracy rate is higher. Through the reservoir development concepts simulation and field practical application, the calculation is more accurate and higher.

  19. Geohydrology, water quality, and simulation of ground-water flow in the vicinity of a former waste-oil refinery near Westville, Indiana, 1997-2000

    USGS Publications Warehouse

    Duwelius, Richard F.; Yeskis, Douglas J.; Wilson, John T.; Robinson, Bret A.

    2002-01-01

    A three-dimensional, four layer groundwater- flow model was constructed and calibrated to match ground-water levels and streamflow measured during December 1997. The model was used to simulate possible mechanisms of contaminant release, the effect of increased pumpage from water-supply wells, and pumping at the leading edge of the plume as a possible means of remediation. Based on simulation of threewaste-oil lagoons, a vertical hydraulic conductivity of 0.2 feet per day was required to move contaminants into the bottom layer of the model at a constant leakage rate of about 98 gallons per minute. Simulations of a disposal well in layer 3 of the model indicated an injection rate of 50 gallons per minute was necessary to spread contaminants vertically in the aquifer. Simulated pumping rates of about 300 and 1,000 gallons per minute were required for watersupply wells at the Town of Westville and the Westville Correctional Facility to draw water from the plume of 1,4-dioxane. Simulated pumping from hypothetical wells at the leading edge of the plume indicated that three wells, each pumping 25 gallons per minute from model layer 3, would capture the plume of 1,4-dioxane.

  20. NNLOPS accurate associated HW production

    NASA Astrophysics Data System (ADS)

    Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia

    2016-06-01

    We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.

  1. Bubble bursting as an aerosol generation mechanism during an oil spill in the deep-sea environment: molecular dynamics simulations of oil alkanes and dispersants in atmospheric air/salt water interfaces.

    PubMed

    Liyana-Arachchi, Thilanga P; Zhang, Zenghui; Ehrenhauser, Franz S; Avij, Paria; Valsaraj, Kalliat T; Hung, Francisco R

    2014-01-01

    Potential of mean force (PMF) calculations and molecular dynamics (MD) simulations were performed to investigate the properties of oil n-alkanes [i.e., n-pentadecane (C15), n-icosane (C20) and n-triacontane (C30)], as well as several surfactant species [i.e., the standard anionic surfactant sodium dodecyl sulfate (SDS), and three model dispersants similar to the Tween and Span species present in Corexit 9500A] at air/salt water interfaces. This study was motivated by the 2010 Deepwater Horizon (DWH) oil spill, and our simulation results show that, from the thermodynamic point of view, the n-alkanes and the model dispersants have a strong preference to remain at the air/salt water interface, as indicated by the presence of deep free energy minima at these interfaces. The free energy minimum of these n-alkanes becomes deeper as their chain length increases, and as the concentration of surfactant species at the interface increases. The n-alkanes tend to adopt a flat orientation and form aggregates at the bare air/salt water interface. When this interface is coated with surfactants, the n-alkanes tend to adopt more tilted orientations with respect to the vector normal to the interface. These simulation results are consistent with the experimental findings reported in the accompanying paper [Ehrenhauser et al., Environ. Sci.: Processes Impacts 2013, in press, (DOI: 10.1039/c3em00390f)]. The fact that these long-chain n-alkanes show a strong thermodynamic preference to remain at the air/salt water interfaces, especially if these interfaces are coated with surfactants, makes these species very likely to adsorb at the surface of bubbles or droplets and be ejected to the atmosphere by sea surface processes such as whitecaps (breaking waves) and bubble bursting. Finally, the experimental finding that more oil hydrocarbons are ejected when Corexit 9500A is present in the system is consistent with the deeper free energy minima observed for the n-alkanes at the air/salt water

  2. Deep oxidative desulfurization of dibenzothiophene in simulated oil and real diesel using heteropolyanion-substituted hydrotalcite-like compounds as catalysts.

    PubMed

    Yu, Fengli; Wang, Rui

    2013-01-01

    Three heteropolyanion substituted hydrotalcite-like compounds (HPA-HTLcs) including Mg₉Al₃(OH)₂₄[PW₁₂O₄₀](MgAl-PW₁₂), Mg₉Al₃(OH)₂₄[PMo₁₂O₄₀] (MgAl-PMo₁₂) and Mg₁₂Al₄(OH)₃₂[SiW₁₂O₄₀] (MgAl-SiW₁₂), were synthesized, characterized and used as catalysts for the oxidative desulfurization of simulated oil (dibenzothiophene, DBT, in n-octane). MgAl-PMo₁₂ was identified as an effective catalyst for the oxidative removal of DBT under very mild conditions of atmospheric pressure and 60 °C in a biphasic system using hydrogen peroxide as oxidant and acetonitrile as extractant. The conversion of DBT was nearly 100%. As a result, because of the influence of the electron density and the space steric hindrance, the oxidation reactivity of the different sulfur compounds in simulated oil followed the order DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT) > thiophene (TH). When the reaction is finished, the catalysts can be recovered from the acetonitrile phase by filtration. The recovered MgAl-PMo₁₂ retains nearly the same catalytic activity as the fresh material. Moreover, MgAl-PMo₁₂ was found to exhibit an ideal catalytic activity in the oxidative desulfurization of real diesel resulting in a total remaining sulfur content of 9.12 ppm(w). PMID:24284486

  3. Identification and quantification of mixed sources of oil spills based on distributions and isotope profiles of long-chain n-alkanes.

    PubMed

    Li, Yun; Xiong, Yongqiang

    2009-12-01

    Combined with quantitative determination of concentration and isotopic composition of petroleum hydrocarbons, weathering simulation experiments on artificially mixed oils and their two end-member oils are performed for identification and quantification of mixed sources. The >C(18)n-alkanes show no appreciable losses during a short-term weathering process. An approach based on distribution of long-chain n-alkanes (>C(18)) is suggested for estimating the contribution proportion of each source in mixed oils. Stable carbon isotope profile of individual n-alkanes is a powerful tool to differentiate sources of oil spills, but unavailable to accurately allocate each contribution due to a relatively large analytical error.

  4. Migration of epoxidised soybean oil from PVC gaskets of commercial lids: simulation of migration under various conditions and screening of food products from Czech markets.

    PubMed

    Hanušová, Kristýna; Vrbík, Karel; Rajchl, Aleš; Dobiáš, Jaroslav; Sosnovcová, Jitka

    2015-01-01

    Previous studies have shown that a large number of polyvinylchloride (PVC) lid gaskets exceed the existing migration limits for epoxidised soybean oil (ESBO) and correct prediction of ESBO release into food therefore appears to be a difficult issue. ESBO migration from PVC gaskets of metal closures into food simulants and food products from the Czech market is evaluated during a survey in 2009 and subsequently one in 2012 to assess progress in lid manufacturing and official testing conditions. ESBO migration from lids into various food simulants was studied at various temperatures (25, 40 and 60°C) during storage times up to 12 months. ESBO released into food simulants or food products was transmethylated, derivatised and analysed by GC-MS. The levels of ESBO migration in foodstuffs in 2012 exceeded the specific migration limit (SML) in fewer products in comparison with the previous survey. However, most of the products were analysed at a time far from the expiry date and exceedance of the SML at the end of the product shelf life is not therefore excluded. More severe test conditions (60°C for 10 days) for specific migration given by the current European Union legislation (Regulation (EU) No. 10/2011) still seem to be insufficient for the simulation of ESBO migration during long-term storage. PMID:25685888

  5. DEROCS: A computer program to simulate offshore oil and natural gas development scenarios and onshore service base requirements

    USGS Publications Warehouse

    Marcus, Philip A.; Smith, E.T.; Robinson, S.R.; Wong, A.T.

    1977-01-01

    The FORTRAN IV (H) computer program, DEROCS, constructs Outer Continental Shelf (OCS) resource development scenarios and quantifies the requirements for and impacts of the operation of the onshore service bases necessary to support offshore oil and gas operations. The acronym DEROCS stands for 'Development of Energy Resources of the Outer Continental Shelf.' The user may specify the number, timing, and amounts of offshore oil and natural gas finds, onshore service base locations, and multiplier relationships between offshore development activities and onshore land, supply, labor and facility requirements. The program determines schedules of platform installation, development drilling, production from platforms, and well workover, and calculates on a yearly basis the requirements for and impacts of the operation of the onshore service bases demanded by offshore activities. We present two examples of program application.

  6. Accurate description of calcium solvation in concentrated aqueous solutions.

    PubMed

    Kohagen, Miriam; Mason, Philip E; Jungwirth, Pavel

    2014-07-17

    Calcium is one of the biologically most important ions; however, its accurate description by classical molecular dynamics simulations is complicated by strong electrostatic and polarization interactions with surroundings due to its divalent nature. Here, we explore the recently suggested approach for effectively accounting for polarization effects via ionic charge rescaling and develop a new and accurate parametrization of the calcium dication. Comparison to neutron scattering and viscosity measurements demonstrates that our model allows for an accurate description of concentrated aqueous calcium chloride solutions. The present model should find broad use in efficient and accurate modeling of calcium in aqueous environments, such as those encountered in biological and technological applications.

  7. Approaching system equilibrium with accurate or not accurate feedback information in a two-route system

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-mei; Xie, Dong-fan; Li, Qi

    2015-02-01

    With the development of intelligent transport system, advanced information feedback strategies have been developed to reduce traffic congestion and enhance the capacity. However, previous strategies provide accurate information to travelers and our simulation results show that accurate information brings negative effects, especially in delay case. Because travelers prefer to the best condition route with accurate information, and delayed information cannot reflect current traffic condition but past. Then travelers make wrong routing decisions, causing the decrease of the capacity and the increase of oscillations and the system deviating from the equilibrium. To avoid the negative effect, bounded rationality is taken into account by introducing a boundedly rational threshold BR. When difference between two routes is less than the BR, routes have equal probability to be chosen. The bounded rationality is helpful to improve the efficiency in terms of capacity, oscillation and the gap deviating from the system equilibrium.

  8. Natural removal of added N-nutrients, reactive phosphorus, crude oil, and heavy metals from the water phase in a simulated water/sediment system

    SciTech Connect

    Lam-Leung, S.Y.; Cheung, M.T.; He, Y.Q.

    1996-08-01

    Water/sediment simulation systems were constructed by using an aquarium (0.45 x 0.29 x 0.35 m{sup 3}), filled with suitable amounts of water and sediment collected from three selected locations: Lan Hau Shan (LHS), Tai Hu (TH), and Loong Yu Tao (LYT) of the Zhujiang (Pearl River) Estuary of China in November 1992 at low-tide period. The salinities of the water samples collected form LHS, TH, LYT were found to be 0.2, 4.6, 16.2 g L{sup -1}, respectively. Known amounts of ammonium, nitrate, nitrite, reactive phosphorous, crude oil, arsenate(III), cadmium (II), copper(II), and zinc(II) were added as pollutants into each of the water/sediment simulation systems. The rates of the natural removal of each added pollutant in all water/sediment simulation systems were studied by monitoring their concentrations at various intrevals in the investigation period. Except for Cr(III) and reactive phosphorous in the water/sediment systems of the LHS, TH, and LYT sites, and nitrate in the TH and LYT sites, the concentrations of the added pollutants in the water phase of the studied systems under a flow-condition simulation were reduced to 8% or less of the corresponding added amount on or before the 12th day by natural processes. The rate of self-purification and the estimated assimulative capacity of each added pollutant in all water/sediment simulation systems is discussed. 30 refs., 11 figs., 4 tabs.

  9. World oil

    NASA Astrophysics Data System (ADS)

    Sweeney, J. L.

    1982-06-01

    Results obtained through the application of 10 prominent world oil or world energy models to 12 scenarios are reported. These scenarios were designed to bound the range of likely future world oil market outcomes. Conclusions relate to oil market trends, impacts of policies on oil prices, security of oil supplies, impacts of policies on oil security problems, use of the oil import premium in policymaking, the transition to oil substitutes, and the state of the art of world oil modeling.

  10. Decision support system for managing oil spill events.

    PubMed

    Keramitsoglou, Iphigenia; Cartalis, Constantinos; Kassomenos, Pavlos

    2003-08-01

    The Mediterranean environment is exposed to various hazards, including oil spills, forest fires, and floods, making the development of a decision support system (DSS) for emergency management an objective of utmost importance. The present work presents a complete DSS for managing marine pollution events caused by oil spills. The system provides all the necessary tools for early detection of oil-spills from satellite images, monitoring of their evolution, estimation of the accident consequences and provision of support to responsible Public Authorities during clean-up operations. The heart of the system is an image processing-geographic information system and other assistant individual software tools that perform oil spill evolution simulation and all other necessary numerical calculations as well as cartographic and reporting tasks related to a specific management of the oil spill event. The cartographic information is derived from the extant general maps representing detailed information concerning several regional environmental and land-cover characteristics as well as financial activities of the application area. Early notification of the authorities with up-to-date accurate information on the position and evolution of the oil spill, combined with the detailed coastal maps, is of paramount importance for emergency assessment and effective clean-up operations that would prevent environmental hazard. An application was developed for the Region of Crete, an area particularly vulnerable to oil spills due to its location, ecological characteristics, and local economic activities.

  11. Aminosilica materials as adsorbents for the selective removal of aldehydes and ketones from simulated bio-oil.

    PubMed

    Drese, Jeffrey H; Talley, Anne D; Jones, Christopher W

    2011-03-21

    The fast pyrolysis of biomass is a potential route to the production of liquid biorenewable fuel sources. However, degradation of the bio-oil mixtures due to reaction of oxygenates, such as aldehydes and ketones, reduces the stability of the liquids and can impact long-term storage and shipping. Herein, solid aminosilica adsorbents are described for the selective adsorptive removal of reactive aldehyde and ketone species. Three aminosilica adsorbents are prepared through the reaction of amine-containing silanes with pore-expanded mesoporous silica. A fourth aminosilica adsorbent is prepared through the ring-opening polymerization of aziridine from pore-expanded mesoporous silica. Adsorption experiments with a representative mixture of bio-oil model compounds are presented using each adsorbent at room temperature and 45 °C. The adsorbent comprising only primary amines adsorbs the largest amount of aldehydes and ketones. The overall reactivity of this adsorbent increases with increasing temperature. Additional aldehyde screening experiments show that the reactivity of aldehydes with aminosilicas varies depending on their chemical functionality. Initial attempts to regenerate an aminosilica adsorbent by acid hydrolysis show that they can be at least partially regenerated for further use. PMID:21246749

  12. Exploring Oil Spills.

    ERIC Educational Resources Information Center

    Czerniak, Charlene M.; And Others

    1996-01-01

    Presents activities in which elementary and middle school students work together to gain environmental awareness about oil spills. Involves students experiencing a simulated oil spill and attempting to clean it up. Discusses the use of children's literature after the activity in evaluation of the activity. (JRH)

  13. Running Out Of and Into Oil. Analyzing Global Oil Depletion and Transition Through 2050

    SciTech Connect

    Greene, David L.; Hopson, Janet L.; Li, Jia

    2003-10-01

    This report presents a risk analysis of world conventional oil resource production, depletion, expansion, and a possible transition to unconventional oil resources such as oil sands, heavy oil and shale oil over the period 2000 to 2050. Risk analysis uses Monte Carlo simulation methods to produce a probability distribution of outcomes rather than a single value.

  14. Accurate determination of characteristic relative permeability curves

    NASA Astrophysics Data System (ADS)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  15. Numerical modeling of the simulated gas hydrate production test at Mallik 2L-38 in the pilot scale pressure reservoir LARS - Applying the "foamy oil" model

    NASA Astrophysics Data System (ADS)

    Abendroth, Sven; Thaler, Jan; Klump, Jens; Schicks, Judith; Uddin, Mafiz

    2014-05-01

    In the context of the German joint project SUGAR (Submarine Gas Hydrate Reservoirs: exploration, extraction and transport) we conducted a series of experiments in the LArge Reservoir Simulator (LARS) at the German Research Centre of Geosciences Potsdam. These experiments allow us to investigate the formation and dissociation of hydrates at large scale laboratory conditions. We performed an experiment similar to the field-test conditions of the production test in the Mallik gas hydrate field (Mallik 2L-38) in the Beaufort Mackenzie Delta of the Canadian Arctic. The aim of this experiment was to study the transport behavior of fluids in gas hydrate reservoirs during depressurization (see also Heeschen et al. and Priegnitz et al., this volume). The experimental results from LARS are used to provide details about processes inside the pressure vessel, to validate the models through history matching, and to feed back into the design of future experiments. In experiments in LARS the amount of methane produced from gas hydrates was much lower than expected. Previously published models predict a methane production rate higher than the one observed in experiments and field studies (Uddin et al. 2010; Wright et al. 2011). The authors of the aforementioned studies point out that the current modeling approach overestimates the gas production rate when modeling gas production by depressurization. They suggest that trapping of gas bubbles inside the porous medium is responsible for the reduced gas production rate. They point out that this behavior of multi-phase flow is not well explained by a "residual oil" model, but rather resembles a "foamy oil" model. Our study applies Uddin's (2010) "foamy oil" model and combines it with history matches of our experiments in LARS. Our results indicate a better agreement between experimental and model results when using the "foamy oil" model instead of conventional models of gas flow in water. References Uddin M., Wright J.F. and Coombe D

  16. Reservoir characterization and enhanced oil recovery research

    SciTech Connect

    Lake, L.W.; Pope, G.A.; Schechter, R.S.

    1992-03-01

    The research in this annual report falls into three tasks each dealing with a different aspect of enhanced oil recovery. The first task strives to develop procedures for accurately modeling reservoirs for use as input to numerical simulation flow models. This action describes how we have used a detail characterization of an outcrop to provide insights into what features are important to fluid flow modeling. The second task deals with scaling-up and modeling chemical and solvent EOR processes. In a sense this task is the natural extension of task 1 and, in fact, one of the subtasks uses many of the same statistical procedures for insight into the effects of viscous fingering and heterogeneity. The final task involves surfactants and their interactions with carbon dioxide and reservoir minerals. This research deals primarily with phenomena observed when aqueous surfactant solutions are injected into oil reservoirs.

  17. MICROBIAL POPULATION CHANGES DURING BIOREMEDIATION OF AN EXPERIMENTAL OIL SPILL

    EPA Science Inventory

    Three crude oil bioremediation techniques were applied in a randomized block field experiment simulating a coastal oil-spill. Four treatments (no oil control, oil alone, oil + nutrients, and oil + nutrients + an indigenous inoculum) were applied. In-situ microbial community str...

  18. Profitable capitation requires accurate costing.

    PubMed

    West, D A; Hicks, L L; Balas, E A; West, T D

    1996-01-01

    In the name of costing accuracy, nurses are asked to track inventory use on per treatment basis when more significant costs, such as general overhead and nursing salaries, are usually allocated to patients or treatments on an average cost basis. Accurate treatment costing and financial viability require analysis of all resources actually consumed in treatment delivery, including nursing services and inventory. More precise costing information enables more profitable decisions as is demonstrated by comparing the ratio-of-cost-to-treatment method (aggregate costing) with alternative activity-based costing methods (ABC). Nurses must participate in this costing process to assure that capitation bids are based upon accurate costs rather than simple averages. PMID:8788799

  19. User's guide and history of ANFO (ammonium nitrate/fuel oil) as a nuclear weapons effect simulation explosive. Technical report

    SciTech Connect

    Petes, J.; Miller, R.; McMullan, F.

    1983-03-31

    The history of the development and use of ANFO as a nuclear-weapons blast, cratering, and ground-shock simulation source, is traced from 1966 to 1976 when the first full-scale target-testing operation was conducted on DICE THROW with a 600-ton ANFO charge. The results of the development tests, of DICE THROW, and of subsequent tests with ANFO through PRE-DIRECT COURSE in 1982, are given and analyzed in terms of explosive-charge performance. The results indicate that ANFO is a safe, economical, and reliable explosive source for effects simulation purposes. The details presented serve as a guide for utilization of ANFO for future similar and more-demanding simulation purposes.

  20. Simulations of a dielectrophoretic membrane filtration process for removal of water droplets from water-in-oil emulsions.

    PubMed

    Molla, Shahnawaz H; Masliyah, Jacob H; Bhattacharjee, Subir

    2005-07-01

    A novel separation technique based on simultaneous application of AC dielectrophoresis and preferential transport through a semipermeable hydrophilic membrane is proposed for separation of small amounts of emulsified water droplets from a water-in-oil emulsion. Embedding an array of parallel microelectrodes on a membrane matrix, followed by application of an AC potential to these electrodes, can result in capturing the water droplets onto the membranes from the emulsion during a crossflow filtration process. The present paper describes the theoretical principles underlying such a process, and describes a simple mathematical framework based on trajectory analysis for assessing the separation efficiency of such a technique. The results indicate that superimposition of an AC dielectrophoretic field can significantly enhance the preferential transport of the emulsified water through the membrane in a crossflow filtration device. This can lead to a highly efficient continuous separation process for dilute emulsions.

  1. Inhibition of lipase-catalyzed hydrolysis of emulsified triglyceride oils by low-molecular weight surfactants under simulated gastrointestinal conditions.

    PubMed

    Li, Yan; McClements, David Julian

    2011-10-01

    The effect of low-molecular weight surfactants on the digestibility of lipids in protein-stabilized corn oil-in-water emulsions was studied using an in vitro digestion model. The impact of non-ionic (Tween 20, Tween 80, Brij35), anionic (SDS), and cationic (DTAB) surfactants on the rate and extent of lipid digestion was studied. All surfactants were found to inhibit lipid digestion at sufficiently high concentrations, with half-maximal inhibitory concentrations (IC50) of 1.2% for Tween 20, 0.7% for Tween 80, 2.8% for Brij35, 1.1% for SDS, and 1.4% for DTAB. The effectiveness of the surfactants at inhibiting lipid digestion was therefore not strongly correlated to the electrical characteristics of the surfactant head group, since the IC50 increased in the following order: Tween 80>SDS>Tween 20>DTAB>Brij35. The ability of these low-molecular weight surfactants to inhibit lipid digestion was attributed to a number of potential mechanisms: (i) prevention of lipase/co-lipase adsorption to the oil-water interface; (ii) formation of interfacial complexes; (iii) direct interaction and inactivation of lipase/co-lipase. Interestingly, DTAB increased the rate and extent of lipid digestion when present at relatively low concentrations. This may have been because this cationic surfactant facilitated the adsorption of lipase to the droplet surfaces through electrostatic attraction, or it bound directly to the lipase molecule thereby changing its structure and activity. A number of the surfactants themselves were found to be susceptible to enzyme digestion by pancreatic enzymes in the absence of lipids: Tween 20, Tween 80, Brij35, and DTAB. This work has important implications for the development of emulsion-based delivery systems for food and pharmaceutical applications.

  2. Utah Heavy Oil Program

    SciTech Connect

    J. Bauman; S. Burian; M. Deo; E. Eddings; R. Gani; R. Goel; C.K. Huang; M. Hogue; R. Keiter; L. Li; J. Ruple; T. Ring; P. Rose; M. Skliar; P.J. Smith; J.P. Spinti; P. Tiwari; J. Wilkey; K. Uchitel

    2009-10-20

    The Utah Heavy Oil Program (UHOP) was established in June 2006 to provide multidisciplinary research support to federal and state constituents for addressing the wide-ranging issues surrounding the creation of an industry for unconventional oil production in the United States. Additionally, UHOP was to serve as an on-going source of unbiased information to the nation surrounding technical, economic, legal and environmental aspects of developing heavy oil, oil sands, and oil shale resources. UHOP fulGilled its role by completing three tasks. First, in response to the Energy Policy Act of 2005 Section 369(p), UHOP published an update report to the 1987 technical and economic assessment of domestic heavy oil resources that was prepared by the Interstate Oil and Gas Compact Commission. The UHOP report, entitled 'A Technical, Economic, and Legal Assessment of North American Heavy Oil, Oil Sands, and Oil Shale Resources' was published in electronic and hard copy form in October 2007. Second, UHOP developed of a comprehensive, publicly accessible online repository of unconventional oil resources in North America based on the DSpace software platform. An interactive map was also developed as a source of geospatial information and as a means to interact with the repository from a geospatial setting. All documents uploaded to the repository are fully searchable by author, title, and keywords. Third, UHOP sponsored Give research projects related to unconventional fuels development. Two projects looked at issues associated with oil shale production, including oil shale pyrolysis kinetics, resource heterogeneity, and reservoir simulation. One project evaluated in situ production from Utah oil sands. Another project focused on water availability and produced water treatments. The last project considered commercial oil shale leasing from a policy, environmental, and economic perspective.

  3. Using Concepts in Literature-based Discovery: Simulating Swanson's Raynaud-Fish Oil and Migraine-Magnesium Discoveries.

    ERIC Educational Resources Information Center

    Weeber, Marc; Klein, Henny; de Jong-van den Berg, Lolkje T. W.; Vos, Rein

    2001-01-01

    Proposes a two-step model of discovery in which new scientific hypotheses can be generated and subsequently tested. Applying advanced natural language processing techniques to find biomedical concepts in text, the model is implemented in a versatile interactive discovery support tool. This tool is used to successfully simulate Don R. Swanson's…

  4. Calculating the binding free energies of charged species based on explicit-solvent simulations employing lattice-sum methods: An accurate correction scheme for electrostatic finite-size effects

    NASA Astrophysics Data System (ADS)

    Rocklin, Gabriel J.; Mobley, David L.; Dill, Ken A.; Hünenberger, Philippe H.

    2013-11-01

    The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges -5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol-1) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non-periodic PB

  5. Calculating the binding free energies of charged species based on explicit-solvent simulations employing lattice-sum methods: An accurate correction scheme for electrostatic finite-size effects

    SciTech Connect

    Rocklin, Gabriel J.; Mobley, David L.; Dill, Ken A.; Hünenberger, Philippe H.

    2013-11-14

    The calculation of a protein-ligand binding free energy based on molecular dynamics (MD) simulations generally relies on a thermodynamic cycle in which the ligand is alchemically inserted into the system, both in the solvated protein and free in solution. The corresponding ligand-insertion free energies are typically calculated in nanoscale computational boxes simulated under periodic boundary conditions and considering electrostatic interactions defined by a periodic lattice-sum. This is distinct from the ideal bulk situation of a system of macroscopic size simulated under non-periodic boundary conditions with Coulombic electrostatic interactions. This discrepancy results in finite-size effects, which affect primarily the charging component of the insertion free energy, are dependent on the box size, and can be large when the ligand bears a net charge, especially if the protein is charged as well. This article investigates finite-size effects on calculated charging free energies using as a test case the binding of the ligand 2-amino-5-methylthiazole (net charge +1 e) to a mutant form of yeast cytochrome c peroxidase in water. Considering different charge isoforms of the protein (net charges −5, 0, +3, or +9 e), either in the absence or the presence of neutralizing counter-ions, and sizes of the cubic computational box (edges ranging from 7.42 to 11.02 nm), the potentially large magnitude of finite-size effects on the raw charging free energies (up to 17.1 kJ mol{sup −1}) is demonstrated. Two correction schemes are then proposed to eliminate these effects, a numerical and an analytical one. Both schemes are based on a continuum-electrostatics analysis and require performing Poisson-Boltzmann (PB) calculations on the protein-ligand system. While the numerical scheme requires PB calculations under both non-periodic and periodic boundary conditions, the latter at the box size considered in the MD simulations, the analytical scheme only requires three non

  6. Corn oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn oil is a popular vegetable oil in the US and in many other countries. Because of its pleasant nutty flavor, its good stability, and its popularity for making margarines, corn oil has long been considered a premium vegetable oil. Among all of the vegetable oils, corn oil ranks tenth in terms of ...

  7. Beads made of cyclodextrin and oil for the oral delivery of lipophilic drugs: in vitro studies in simulated gastro-intestinal fluids.

    PubMed

    Hamoudi, M; Fattal, E; Gueutin, C; Nicolas, V; Bochot, A

    2011-09-20

    The aim of this work was to investigate the stability in vitro, in simulated gastro-intestinal fluids, of beads, made of α-cyclodextrin and soybean oil, and to study the release of progesterone, a model of lipophilic drug. This was evaluated over time by the monitoring of the proportion of intact beads, their volume and the percentage of progesterone dissolved. Their incubation in the simulated gastric fluid provoked a moderate reduction of their number (20%) and a decrease of their volume (50%) after 55 min. Whatever the intestinal medium subsequently introduced, bead number and volume decreased more until bead disintegration that appeared faster in sodium taurocholate rich-medium. In such fluid, the amount of progesterone dissolved increased rapidly between 65 and 180 min, with both beads and emulsion to be equal after 85 min. With soft capsules, the increase was more gradual. In sodium taurocholate free-medium, more progesterone was dissolved from the emulsion than from beads or soft capsules. The release of progesterone from beads resulted from the erosion of their matrix and its partition equilibrium between oily micro-droplets and aqueous phase. The original structure of beads confers to this multiparticulate system interesting properties for the oral delivery of lipophilic drugs.

  8. Accurate documentation and wound measurement.

    PubMed

    Hampton, Sylvie

    This article, part 4 in a series on wound management, addresses the sometimes routine yet crucial task of documentation. Clear and accurate records of a wound enable its progress to be determined so the appropriate treatment can be applied. Thorough records mean any practitioner picking up a patient's notes will know when the wound was last checked, how it looked and what dressing and/or treatment was applied, ensuring continuity of care. Documenting every assessment also has legal implications, demonstrating due consideration and care of the patient and the rationale for any treatment carried out. Part 5 in the series discusses wound dressing characteristics and selection.

  9. Predicting hydration Gibbs energies of alkyl-aromatics using molecular simulation: a comparison of current force fields and the development of a new parameter set for accurate solvation data.

    PubMed

    Garrido, Nuno M; Jorge, Miguel; Queimada, António J; Gomes, José R B; Economou, Ioannis G; Macedo, Eugénia A

    2011-10-14

    The Gibbs energy of hydration is an important quantity to understand the molecular behavior in aqueous systems at constant temperature and pressure. In this work we review the performance of some popular force fields, namely TraPPE, OPLS-AA and Gromos, in reproducing the experimental Gibbs energies of hydration of several alkyl-aromatic compounds--benzene, mono-, di- and tri-substituted alkylbenzenes--using molecular simulation techniques. In the second part of the paper, we report a new model that is able to improve such hydration energy predictions, based on Lennard Jones parameters from the recent TraPPE-EH force field and atomic partial charges obtained from natural population analysis of density functional theory calculations. We apply a scaling factor determined by fitting the experimental hydration energy of only two solutes, and then present a simple rule to generate atomic partial charges for different substituted alkyl-aromatics. This rule has the added advantages of eliminating the unnecessary assumption of fixed charge on every substituted carbon atom and providing a simple guideline for extrapolating the charge assignment to any multi-substituted alkyl-aromatic molecule. The point charges derived here yield excellent predictions of experimental Gibbs energies of hydration, with an overall absolute average deviation of less than 0.6 kJ mol(-1). This new parameter set can also give good predictive performance for other thermodynamic properties and liquid structural information.

  10. Vegetable oil spills on salt marsh sediments; comparison between sunflower and linseed oils.

    PubMed

    Pereira, M Glória; Mudge, Stephen M; Latchford, John

    2003-09-01

    The effects of a simulated spill of sunflower oil in salt marsh sediments were compared with an experiment with linseed oil. Sunflower and linseed oil penetrated the sediments at the same rates but different adsorption of the oils onto sediment particles resulted in the establishment of anaerobic conditions at shallower depths in sediments contaminated with linseed oil than with sunflower oil. The total lipid content of sunflower oil contaminated sediments remained almost stable for 6 months, whilst only 40% of linseed oil remained in the sediment after 2 months. Numbers of culturable heterotrophic bacteria and aerobic oil degrading bacteria in muddy sediment increased rapidly in response to the presence of the oils but bacterial numbers in sandy sediments increased more slowly for sunflower oil. Changes in fatty acid composition indicate similar degradation pathways for both oils but sunflower oil degraded more slowly than linseed oil and thus has the potential for longer lasting effects in marine environments.

  11. Carbonyl Emissions From Oil and Gas Production Facilities

    NASA Astrophysics Data System (ADS)

    Lyman, S. N.; O'Neil, T.; Tran, T.

    2015-12-01

    to accurately simulate inversion conditions or wintertime chemistry, thus leading to low ozone production in spite of an accurate inventory.

  12. Practical aspects of spatially high accurate methods

    NASA Technical Reports Server (NTRS)

    Godfrey, Andrew G.; Mitchell, Curtis R.; Walters, Robert W.

    1992-01-01

    The computational qualities of high order spatially accurate methods for the finite volume solution of the Euler equations are presented. Two dimensional essentially non-oscillatory (ENO), k-exact, and 'dimension by dimension' ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy, computational cost and oscillatory behavior in supersonic flows with shocks. Inherent steady state convergence difficulties are demonstrated for adaptive stencil algorithms. An exact solution to the heat equation is used to determine reconstruction error, and the computational intensity is reflected in operation counts. Standard MUSCL differencing is included for comparison. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock reflection problem. A vortex-shock interaction demonstrates the ability of the ENO scheme to excel in simulating unsteady high-frequency flow physics.

  13. SPLASH: Accurate OH maser positions

    NASA Astrophysics Data System (ADS)

    Walsh, Andrew; Gomez, Jose F.; Jones, Paul; Cunningham, Maria; Green, James; Dawson, Joanne; Ellingsen, Simon; Breen, Shari; Imai, Hiroshi; Lowe, Vicki; Jones, Courtney

    2013-10-01

    The hydroxyl (OH) 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. In this proposal, we request ATCA time to follow up OH maser candidates. This will give us accurate (~10") positions of the masers, which can be compared to other maser positions from HOPS, MMB and MALT-45 and will provide full polarisation measurements towards a sample of OH masers that have not been observed in MAGMO.

  14. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  15. Accurate thickness measurement of graphene.

    PubMed

    Shearer, Cameron J; Slattery, Ashley D; Stapleton, Andrew J; Shapter, Joseph G; Gibson, Christopher T

    2016-03-29

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  16. Oil Production

    1989-07-01

    A horizontal and slanted well model was developed and incorporated into BOAST, a black oil simulator, to predict the potential production rates for such wells. The HORIZONTAL/SLANTED WELL MODEL can be used to calculate the productivity index, based on the length and location of the wellbore within the block, for each reservoir grid block penetrated by the horizontal/slanted wellbore. The well model can be run under either pressure or rate constraints in which wellbore pressuresmore » can be calculated as an option of infinite-conductivity. The model can simulate the performance of multiple horizontal/slanted wells in any geometric combination within reservoirs.« less

  17. 14 CFR 29.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil quantity indicator. 29.1551 Section 29... Placards § 29.1551 Oil quantity indicator. Each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil....

  18. 25 CFR 226.38 - Measuring and storing oil.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Measuring and storing oil. 226.38 Section 226.38 Indians... LANDS FOR OIL AND GAS MINING Requirements of Lessees § 226.38 Measuring and storing oil. All production.... Facilities suitable for containing and measuring accurately all crude oil produced from the wells shall...

  19. 14 CFR 25.1551 - Oil quantity indication.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil quantity indication. 25.1551 Section 25... Placards § 25.1551 Oil quantity indication. Each oil quantity indicating means must be marked to indicate the quantity of oil readily and accurately....

  20. 14 CFR 23.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil quantity indicator. 23.1551 Section 23... Information Markings and Placards § 23.1551 Oil quantity indicator. Each oil quantity indicator must be marked in sufficient increments to indicate readily and accurately the quantity of oil....

  1. 14 CFR 27.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil quantity indicator. 27.1551 Section 27... § 27.1551 Oil quantity indicator. Each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil....

  2. 14 CFR 27.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil quantity indicator. 27.1551 Section 27... § 27.1551 Oil quantity indicator. Each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil....

  3. 14 CFR 29.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil quantity indicator. 29.1551 Section 29... Placards § 29.1551 Oil quantity indicator. Each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil....

  4. 14 CFR 25.1551 - Oil quantity indication.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil quantity indication. 25.1551 Section 25... Placards § 25.1551 Oil quantity indication. Each oil quantity indicating means must be marked to indicate the quantity of oil readily and accurately....

  5. 25 CFR 226.38 - Measuring and storing oil.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 1 2013-04-01 2013-04-01 false Measuring and storing oil. 226.38 Section 226.38 Indians... LANDS FOR OIL AND GAS MINING Requirements of Lessees § 226.38 Measuring and storing oil. All production.... Facilities suitable for containing and measuring accurately all crude oil produced from the wells shall...

  6. 14 CFR 27.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil quantity indicator. 27.1551 Section 27... § 27.1551 Oil quantity indicator. Each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil....

  7. 25 CFR 226.38 - Measuring and storing oil.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 1 2011-04-01 2011-04-01 false Measuring and storing oil. 226.38 Section 226.38 Indians... LANDS FOR OIL AND GAS MINING Requirements of Lessees § 226.38 Measuring and storing oil. All production.... Facilities suitable for containing and measuring accurately all crude oil produced from the wells shall...

  8. 14 CFR 23.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Oil quantity indicator. 23.1551 Section 23... Information Markings and Placards § 23.1551 Oil quantity indicator. Each oil quantity indicator must be marked in sufficient increments to indicate readily and accurately the quantity of oil....

  9. 14 CFR 23.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil quantity indicator. 23.1551 Section 23... Information Markings and Placards § 23.1551 Oil quantity indicator. Each oil quantity indicator must be marked in sufficient increments to indicate readily and accurately the quantity of oil....

  10. 14 CFR 25.1551 - Oil quantity indication.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil quantity indication. 25.1551 Section 25... Placards § 25.1551 Oil quantity indication. Each oil quantity indicating means must be marked to indicate the quantity of oil readily and accurately....

  11. 14 CFR 23.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil quantity indicator. 23.1551 Section 23... Information Markings and Placards § 23.1551 Oil quantity indicator. Each oil quantity indicator must be marked in sufficient increments to indicate readily and accurately the quantity of oil....

  12. 14 CFR 29.1551 - Oil quantity indicator.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil quantity indicator. 29.1551 Section 29... Placards § 29.1551 Oil quantity indicator. Each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil....

  13. 14 CFR 25.1551 - Oil quantity indication.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Oil quantity indication. 25.1551 Section 25... Placards § 25.1551 Oil quantity indication. Each oil quantity indicating means must be marked to indicate the quantity of oil readily and accurately....

  14. 25 CFR 226.38 - Measuring and storing oil.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 1 2014-04-01 2014-04-01 false Measuring and storing oil. 226.38 Section 226.38 Indians... LANDS FOR OIL AND GAS MINING Requirements of Lessees § 226.38 Measuring and storing oil. All production.... Facilities suitable for containing and measuring accurately all crude oil produced from the wells shall...

  15. 25 CFR 226.38 - Measuring and storing oil.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 1 2012-04-01 2011-04-01 true Measuring and storing oil. 226.38 Section 226.38 Indians... LANDS FOR OIL AND GAS MINING Requirements of Lessees § 226.38 Measuring and storing oil. All production.... Facilities suitable for containing and measuring accurately all crude oil produced from the wells shall...

  16. The impact of water temperature on core body temperature of North American river otters (Lutra canadensis) during simulated oil spill recovery washing protocols.

    PubMed

    Stoskopf, M K; Spelman, L H; Sumner, P W; Redmond, D P; Jochem, W J; Levine, J F

    1997-12-01

    Ten North American river otters (Lutra canadensis) were anesthetized with Telazol and instrumented with ingestable radiotelemetry temperature sensors for measuring core body temperature. The otters were then subjected to a washing protocol to simulate rehabilitation following an oil spill contamination. This protocol consisted of a 30-min wash in a 1:16 dilution of dishwashing liquid using either cold (24 degrees C) water or water near baseline core body temperature (38.4 degrees C), followed by a 30-min rinse with water of the same temperature, followed by 10 min of forced hot air drying. Core body temperatures of the otters washed in cold water fell at a median rate of 0.1 degrees C/min, whereas otters washed in warm water maintained stable core temperatures until the completion of the protocol, at which time their core temperatures began to drop at a similar rate. Core temperatures restabilized in both groups, and no statistical difference in core temperature between groups remained 180 min after initiation of the protocol. Efforts to examine the efficacy of supplemental squalene administration to speed the recovery of fur condition and waterproofing were unsuccessful because the washing protocol did not cause loss of coat waterproofing in 8 of the 10 subjects.

  17. Corrosion Resistance of Fe-Al/Al2O3 Duplex Coating on Pipeline Steel X80 in Simulated Oil and Gas Well Environment

    NASA Astrophysics Data System (ADS)

    Huang, Min; Wang, Yu; Wang, Ping-Gu; Shi, Qin-Yi; Zhang, Meng-Xian

    2015-04-01

    Corrosion resistant Fe-Al/Al2O3 duplex coating for pipeline steel X80 was prepared by a combined treatment of low-temperature aluminizing and micro-arc oxidation (MAO). Phase composition and microstructure of mono-layer Fe-Al coating and Fe-Al/Al2O3 duplex coating were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). Corrosion resistance of the coated pipeline steel X80 in a simulated oil and gas well condition was also investigated. Mono-layer Fe-Al coating consists of Fe2Al5 and FeAl, which is a suitable transitional layer for the preparation of ceramic coating by MAO on the surface of pipeline steel X80. Under the same corrosion condition at 373 K for 168 h with 1 MPa CO2 and 0.1 MPa H2S, corrosion weight loss rate of pipeline steel X80 with Fe-Al/Al2O3 duplex coating decreased to 23% of original pipeline steel X80, which improved by 10% than that of pipeline steel X80 with mono-layer Fe-Al coating. It cannot find obvious cracks and pits on the corrosion surface of pipeline steel X80 with Fe-Al/Al2O3 duplex coating.

  18. Analysis of heavy-oil immiscible CO/sub 2/ tertiary coreflood data

    SciTech Connect

    Mayer, E.H.; Earlougher, R.C. Sr.; Spivak, A.; Costa, A.

    1988-02-01

    This paper describes the results of a series of tertiary, immiscible, CO/sub 2/ corefloods of Wilmington field Pliocene reservoir rock containing heavy oil (+- 14/sup 0/ API (+-0.97 g/cm/sup 3/) and +-480 cp (+-480 mPa . s)). An initial set of corefloods defined the recovery potential of the CO/sub 2/ injection, while a series of later tests served to define the process more accurately as applied in the field. In an attempt to understand the displacement mechanism, simulator matching of one of the later, more refined groups of corefloods was performed. The corefloods and simulator work indicate that the incremental recovery is more than can be accounted for by oil-viscosity reduction and crude-oil swelling. The improved performance is attributed to more favorable displacement characteristics and the presence of a free gas saturation in the cores.

  19. Improving a prediction system for oil spills in the Yellow Sea: effect of tides on subtidal flow.

    PubMed

    Kim, Chang-Sin; Cho, Yang-Ki; Choi, Byoung-Ju; Jung, Kyung Tae; You, Sung Hyup

    2013-03-15

    A multi-nested prediction system for the Yellow Sea using drifter trajectory simulations was developed to predict the movements of an oil spill after the MV Hebei Spirit accident. The speeds of the oil spill trajectories predicted by the model without tidal forcing were substantially faster than the observations; however, predictions taking into account the tides, including both tidal cycle and subtidal periods, were satisfactorily improved. Subtidal flow in the simulation without tides was stronger than in that with tides because of reduced frictional effects. Friction induced by tidal stress decelerated the southward subtidal flows driven by northwesterly winter winds along the Korean coast of the Yellow Sea. These results strongly suggest that in order to produce accurate predictions of oil spill trajectories, simulations must include tidal effects, such as variations within a tidal cycle and advections over longer time scales in tide-dominated areas.

  20. 78 FR 43959 - In the Matter of American Technologies Group, Inc., Bonanza Oil & Gas, Inc., and Gulf Coast Oil...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-22

    ... COMMISSION In the Matter of American Technologies Group, Inc., Bonanza Oil & Gas, Inc., and Gulf Coast Oil... information concerning the securities of Bonanza Oil & Gas, Inc. because it has not filed any periodic reports... a lack of current and accurate information concerning the securities of Gulf Coast Oil & Gas,...

  1. Oil-eating microbes control oil slicks

    SciTech Connect

    Graham, J. )

    1992-04-01

    Researchers with Lockheed Missiles and Space Company (LMSC) have demonstrated a new environmentally safe method that uses a naturally occurring seawater microbe, powdered clay, and fertilizer to contain and break down oil spills. The philosophy is to accelerate nature and use natural organisms to break down the oil. While the concept of using oil-eating microbes is not new, this process involves applying a powdered clay, called Petro-Lock, to the slick to coagulate the oil and prevent it from sinking. The microbe, Marine-D, is applied with a nitrogen-based fertilizer to begin digesting the oil. The fertilizer provides nutrients for the microbes, which secrete a fatty acid that can be eaten by plankton. When the microbes have digested all of the oil, they die, sink to the ocean floor, and decompose. Bench and large scale testing results indicate that the microbes digest about 75% of the oil after 36 days. Further testing will incorporate wave action and will simulate deep-water and beach conditions.

  2. A high order accurate difference scheme for complex flow fields

    SciTech Connect

    Dexun Fu; Yanwen Ma

    1997-06-01

    A high order accurate finite difference method for direct numerical simulation of coherent structure in the mixing layers is presented. The reason for oscillation production in numerical solutions is analyzed. It is caused by a nonuniform group velocity of wavepackets. A method of group velocity control for the improvement of the shock resolution is presented. In numerical simulation the fifth-order accurate upwind compact difference relation is used to approximate the derivatives in the convection terms of the compressible N-S equations, a sixth-order accurate symmetric compact difference relation is used to approximate the viscous terms, and a three-stage R-K method is used to advance in time. In order to improve the shock resolution the scheme is reconstructed with the method of diffusion analogy which is used to control the group velocity of wavepackets. 18 refs., 12 figs., 1 tab.

  3. Accurately simulating anisotropic thermal conduction on a moving mesh

    NASA Astrophysics Data System (ADS)

    Kannan, Rahul; Springel, Volker; Pakmor, Rüdiger; Marinacci, Federico; Vogelsberger, Mark

    2016-05-01

    We present a novel implementation of an extremum preserving anisotropic diffusion solver for thermal conduction on the unstructured moving Voronoi mesh of the AREPO code. The method relies on splitting the one-sided facet fluxes into normal and oblique components, with the oblique fluxes being limited such that the total flux is both locally conservative and extremum preserving. The approach makes use of harmonic averaging points and a simple, robust interpolation scheme that works well for strong heterogeneous and anisotropic diffusion problems. Moreover, the required discretization stencil is small. Efficient fully implicit and semi-implicit time integration schemes are also implemented. We perform several numerical tests that evaluate the stability and accuracy of the scheme, including applications such as point explosions with heat conduction and calculations of convective instabilities in conducting plasmas. The new implementation is suitable for studying important astrophysical phenomena, such as the conductive heat transport in galaxy clusters, the evolution of supernova remnants, or the distribution of heat from black hole-driven jets into the intracluster medium.

  4. The importance of accurate atmospheric modeling

    NASA Astrophysics Data System (ADS)

    Payne, Dylan; Schroeder, John; Liang, Pang

    2014-11-01

    This paper will focus on the effect of atmospheric conditions on EO sensor performance using computer models. We have shown the importance of accurately modeling atmospheric effects for predicting the performance of an EO sensor. A simple example will demonstrated how real conditions for several sites in China will significantly impact on image correction, hyperspectral imaging, and remote sensing. The current state-of-the-art model for computing atmospheric transmission and radiance is, MODTRAN® 5, developed by the US Air Force Research Laboratory and Spectral Science, Inc. Research by the US Air Force, Navy and Army resulted in the public release of LOWTRAN 2 in the early 1970's. Subsequent releases of LOWTRAN and MODTRAN® have continued until the present. Please verify that (1) all pages are present, (2) all figures are correct, (3) all fonts and special characters are correct, and (4) all text and figures fit within the red margin lines shown on this review document. Complete formatting information is available at http://SPIE.org/manuscripts Return to the Manage Active Submissions page at http://spie.org/submissions/tasks.aspx and approve or disapprove this submission. Your manuscript will not be published without this approval. Please contact author_help@spie.org with any questions or concerns. The paper will demonstrate the importance of using validated models and local measured meteorological, atmospheric and aerosol conditions to accurately simulate the atmospheric transmission and radiance. Frequently default conditions are used which can produce errors of as much as 75% in these values. This can have significant impact on remote sensing applications.

  5. Analysis of oil consumption in cylinder of diesel engine for optimization of piston rings

    NASA Astrophysics Data System (ADS)

    Zhang, Junhong; Zhang, Guichang; He, Zhenpeng; Lin, Jiewei; Liu, Hai

    2013-01-01

    The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings: (1) The oil evaporation from the liner is determined by the working condition of an engine; (2) The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; (3) With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the

  6. Phase Behavior, Solid Organic Precipitation, and Mobility Characterization Studies in Support of Enhanced Heavy Oil Recovery on the Alaska North Slope

    SciTech Connect

    Shirish Patil; Abhijit Dandekar; Santanu Khataniar

    2008-12-31

    The medium-heavy oil (viscous oil) resources in the Alaska North Slope are estimated at 20 to 25 billion barrels. These oils are viscous, flow sluggishly in the formations, and are difficult to recover. Recovery of this viscous oil requires carefully designed enhanced oil recovery processes. Success of these recovery processes is critically dependent on accurate knowledge of the phase behavior and fluid properties, especially viscosity, of these oils under variety of pressure and temperature conditions. This project focused on predicting phase behavior and viscosity of viscous oils using equations of state and semi-empirical correlations. An experimental study was conducted to quantify the phase behavior and physical properties of viscous oils from the Alaska North Slope oil field. The oil samples were compositionally characterized by the simulated distillation technique. Constant composition expansion and differential liberation tests were conducted on viscous oil samples. Experiment results for phase behavior and reservoir fluid properties were used to tune the Peng-Robinson equation of state and predict the phase behavior accurately. A comprehensive literature search was carried out to compile available compositional viscosity models and their modifications, for application to heavy or viscous oils. With the help of meticulously amassed new medium-heavy oil viscosity data from experiments, a comparative study was conducted to evaluate the potential of various models. The widely used corresponding state viscosity model predictions deteriorate when applied to heavy oil systems. Hence, a semi-empirical approach (the Lindeloff model) was adopted for modeling the viscosity behavior. Based on the analysis, appropriate adjustments have been suggested: the major one is the division of the pressure-viscosity profile into three distinct regions. New modifications have improved the overall fit, including the saturated viscosities at low pressures. However, with the limited

  7. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  8. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  9. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  10. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  11. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  12. A detection method of vegetable oils in edible blended oil based on three-dimensional fluorescence spectroscopy technique.

    PubMed

    Xu, Jing; Liu, Xiao-Fei; Wang, Yu-Tian

    2016-12-01

    Edible blended vegetable oils are made from two or more refined oils. Blended oils can provide a wider range of essential fatty acids than single vegetable oils, which helps support good nutrition. Nutritional components in blended oils are related to the type and content of vegetable oils used, and a new, more accurate, method is proposed to identify and quantify the vegetable oils present using cluster analysis and a Quasi-Monte Carlo integral. Three-dimensional fluorescence spectra were obtained at 250-400nm (excitation) and 260-750nm (emission). Mixtures of sunflower, soybean and peanut oils were used as typical examples to validate the effectiveness of the method.

  13. Accurate, reliable prototype earth horizon sensor head

    NASA Technical Reports Server (NTRS)

    Schwarz, F.; Cohen, H.

    1973-01-01

    The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

  14. Rapid hydropyrolysis of resid oil

    SciTech Connect

    Mathur, V.K.; Salahuddin, M.A.; Mohamed, A.R.

    1994-12-31

    The objective of this investigation was to study the rapid hydropyrolysis of Arabian Light atmospheric resid oil and vacuum resid oil for the production of light distillates. The results of this study have been divided into the effect of exposure time, temperature, and gaseous atmosphere. The heat flux used was in the range of 70 to about 97 watt/cm{sup 2}. The results from ASTM simulated distillation of the hydrogenated oil obtained at various experimental conditions are also presented.

  15. Development of Method for Remaining Life Assessment of Oil-Immersed Transformer

    NASA Astrophysics Data System (ADS)

    Matsui, Tetsuro; Nakahara, Yasuo; Nishiyama, Kazuo; Urabe, Noboru; Itoh, Masayoshi

    This paper presents a method for remaining life assessment of oil-immersed transformers using analyzable structured neural networks. Remaining life assessment of oil-immersed transformer is very important. Furfural method is conventionally used for such an assessment. In the furfural method, the average degree of polymerization is determined by considering the nonlinear correlation between the furfural and average degree of polymerization. The remaining life is estimated by considering the average degree of polymerization. However, a range of estimates of the remaining life is obtained when the furfural method is used, making accurate estimation difficult. The proposed method can be used to estimate the remaining life of an oil-immersed transformer accurately; this method involves analyzable structured neural networks and ensemble method. In the proposed method, not only furfural but also oil temperature, operational status, cooling type, etc., are considered. Since various factors are considered as input variables and a nonlinear model, i.e., artificial neural networks are used, accurate estimation of the remaining life has been realized. The effectiveness of the proposed method is shown by numerical simulation using actual measured data.

  16. Material point method modeling in oil and gas reservoirs

    DOEpatents

    Vanderheyden, William Brian; Zhang, Duan

    2016-06-28

    A computer system and method of simulating the behavior of an oil and gas reservoir including changes in the margins of frangible solids. A system of equations including state equations such as momentum, and conservation laws such as mass conservation and volume fraction continuity, are defined and discretized for at least two phases in a modeled volume, one of which corresponds to frangible material. A material point model technique for numerically solving the system of discretized equations, to derive fluid flow at each of a plurality of mesh nodes in the modeled volume, and the velocity of at each of a plurality of particles representing the frangible material in the modeled volume. A time-splitting technique improves the computational efficiency of the simulation while maintaining accuracy on the deformation scale. The method can be applied to derive accurate upscaled model equations for larger volume scale simulations.

  17. The influence of droplet size and biodegradation on the transport of subsurface oil droplets during the Deepwater Horizon spill: a model sensitivity study

    NASA Astrophysics Data System (ADS)

    North, Elizabeth W.; Adams, E. Eric; Thessen, Anne E.; Schlag, Zachary; He, Ruoying; Socolofsky, Scott A.; Masutani, Stephen M.; Peckham, Scott D.

    2015-02-01

    A better understanding of oil droplet formation, degradation, and dispersal in deep waters is needed to enhance prediction of the fate and transport of subsurface oil spills. This research evaluates the influence of initial droplet size and rates of biodegradation on the subsurface transport of oil droplets, specifically those from the Deepwater Horizon oil spill. A three-dimensional coupled model was employed with components that included analytical multiphase plume, hydrodynamic and Lagrangian models. Oil droplet biodegradation was simulated based on first order decay rates of alkanes. The initial diameter of droplets (10-300 μm) spanned a range of sizes expected from dispersant-treated oil. Results indicate that model predictions are sensitive to biodegradation processes, with depth distributions deepening by hundreds of meters, horizontal distributions decreasing by hundreds to thousands of kilometers, and mass decreasing by 92-99% when biodegradation is applied compared to simulations without biodegradation. In addition, there are two- to four-fold changes in the area of the seafloor contacted by oil droplets among scenarios with different biodegradation rates. The spatial distributions of hydrocarbons predicted by the model with biodegradation are similar to those observed in the sediment and water column, although the model predicts hydrocarbons to the northeast and east of the well where no observations were made. This study indicates that improvement in knowledge of droplet sizes and biodegradation processes is important for accurate prediction of subsurface oil spills.

  18. Enhancement of oxygen mass transfer and gas holdup using palm oil in stirred tank bioreactors with xanthan solutions as simulated viscous fermentation broths.

    PubMed

    Mohd Sauid, Suhaila; Krishnan, Jagannathan; Huey Ling, Tan; Veluri, Murthy V P S

    2013-01-01

    Volumetric mass transfer coefficient (kLa) is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase the kLa. The present study opted for palm oil as the organic phase as it is plentiful in Malaysia. Experiments were carried out to study the effect of viscosity, gas holdup, and kLa on the xanthan solution with different palm oil fractions by varying the agitation rate and aeration rate in a 5 L bench-top bioreactor fitted with twin Rushton turbines. Results showed that 10% (v/v) of palm oil raised the kLa of xanthan solution by 1.5 to 3 folds with the highest kLa value of 84.44 h(-1). It was also found that palm oil increased the gas holdup and viscosity of the xanthan solution. The kLa values obtained as a function of power input, superficial gas velocity, and palm oil fraction were validated by two different empirical equations. Similarly, the gas holdup obtained as a function of power input and superficial gas velocity was validated by another empirical equation. All correlations were found to fit well with higher determination coefficients.

  19. Online monitoring of oil film using electrical capacitance tomography and level set method

    SciTech Connect

    Xue, Q. Ma, M.; Sun, B. Y.; Cui, Z. Q.; Wang, H. X.

    2015-08-15

    In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online.

  20. Online monitoring of oil film using electrical capacitance tomography and level set method

    NASA Astrophysics Data System (ADS)

    Xue, Q.; Sun, B. Y.; Cui, Z. Q.; Ma, M.; Wang, H. X.

    2015-08-01

    In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online.

  1. Online monitoring of oil film using electrical capacitance tomography and level set method.

    PubMed

    Xue, Q; Sun, B Y; Cui, Z Q; Ma, M; Wang, H X

    2015-08-01

    In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online. PMID:26329232

  2. Online monitoring of oil film using electrical capacitance tomography and level set method.

    PubMed

    Xue, Q; Sun, B Y; Cui, Z Q; Ma, M; Wang, H X

    2015-08-01

    In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online.

  3. MODELING DISPERSANT INTERACTIONS WITH OIL SPILLS

    EPA Science Inventory

    EPA is developing a model called the EPA Research Object-Oriented Oil Spill Model (ERO3S) and associated databases to simulate the impacts of dispersants on oil slicks. Because there are features of oil slicks that align naturally with major concepts of object-oriented programmi...

  4. Fluorescence characteristics of oil during the Deepwater Horizon oil spill

    NASA Astrophysics Data System (ADS)

    Coble, P. G.; Conmy, R. N.; Wood, M.; Lee, K.; Kepkay, P.; Li, Z.

    2010-12-01

    Emergency responders, agencies and researchers have tracked oil spilled during the Deepwater Horizon event using a number of techniques, including fluorescence, particle size and chemical analyses. Even though current protocols call for the use of in situ fluorometers to detect the presence of oil throughout the water column, these fluorometers have not been designed to yield information on changes in oil optical properties as it weathers and is chemically and/or physically dispersed. Multi-wavelength (Excitation Emission Matrix or multiple fixed wavelength) fluorometers and particle size analyzers are required to accurately monitor these changing properties in situ and in samples containing the oil suspended as droplets in seawater. Findings reported by the Unified Command Joint Analysis Group on fluorescence, particle size (by LISST) and chemical analysis data will be used to delineate changing oil properties and the results obtained from laboratory experiments using suspensions of Deepwater Horizon source oil will be compared to the environmental data (including information collected via ROV at the well head). The Deepwater Horizon spill was unprecedented in terms of magnitude, depth of the spill and subsurface dispersant application. The work presented here will improve current protocols by highlighting the critical fluorescence wavelengths needed to accurately track oil through marine systems.

  5. Accurate method of modeling cluster scaling relations in modified gravity

    NASA Astrophysics Data System (ADS)

    He, Jian-hua; Li, Baojiu

    2016-06-01

    We propose a new method to model cluster scaling relations in modified gravity. Using a suite of nonradiative hydrodynamical simulations, we show that the scaling relations of accumulated gas quantities, such as the Sunyaev-Zel'dovich effect (Compton-y parameter) and the x-ray Compton-y parameter, can be accurately predicted using the known results in the Λ CDM model with a precision of ˜3 % . This method provides a reliable way to analyze the gas physics in modified gravity using the less demanding and much more efficient pure cold dark matter simulations. Our results therefore have important theoretical and practical implications in constraining gravity using cluster surveys.

  6. Accurate Thermal Conductivities from First Principles

    NASA Astrophysics Data System (ADS)

    Carbogno, Christian

    2015-03-01

    In spite of significant research efforts, a first-principles determination of the thermal conductivity at high temperatures has remained elusive. On the one hand, Boltzmann transport techniques that include anharmonic effects in the nuclear dynamics only perturbatively become inaccurate or inapplicable under such conditions. On the other hand, non-equilibrium molecular dynamics (MD) methods suffer from enormous finite-size artifacts in the computationally feasible supercells, which prevent an accurate extrapolation to the bulk limit of the thermal conductivity. In this work, we overcome this limitation by performing ab initio MD simulations in thermodynamic equilibrium that account for all orders of anharmonicity. The thermal conductivity is then assessed from the auto-correlation function of the heat flux using the Green-Kubo formalism. Foremost, we discuss the fundamental theory underlying a first-principles definition of the heat flux using the virial theorem. We validate our approach and in particular the techniques developed to overcome finite time and size effects, e.g., by inspecting silicon, the thermal conductivity of which is particularly challenging to converge. Furthermore, we use this framework to investigate the thermal conductivity of ZrO2, which is known for its high degree of anharmonicity. Our calculations shed light on the heat resistance mechanism active in this material, which eventually allows us to discuss how the thermal conductivity can be controlled by doping and co-doping. This work has been performed in collaboration with R. Ramprasad (University of Connecticut), C. G. Levi and C. G. Van de Walle (University of California Santa Barbara).

  7. Lavender oil

    MedlinePlus

    ... an oil made from the flowers of lavender plants. Lavender poisoning occurs when someone swallows lavender oil. ... Graeme KA. Toxic plant ingestions. In: Auerbach PS, ed. Wilderness Medicine . ... PA: Elsevier Mosby; 2012:chap 64. Maypole J, Woolf, ...

  8. Oil Spills

    MedlinePlus

    ... is to provide scientific support to the U.S. Coast Guard officers in charge of response operations. In addition ... NOAA Responds to Oil Spills While the U.S. Coast Guard oversees all responses to oil spills and chemical ...

  9. A NEW GENERATION CHEMICAL FLOODING SIMULATOR

    SciTech Connect

    Gary A. Pope; Kamy Sepehrnoori; Mojdeh Delshad

    2003-04-01

    The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved using state-of-the-art algorithms and computers. Such a simulator is not currently available to the industry. The goal of this proposed research is to develop a new-generation chemical flooding simulator that is capable of efficiently and accurately simulating oil reservoirs with at least a million gridblocks in less than one day on massively parallel computers. Task 1 is the formulation and development of solution scheme, Task 2 is the implementation of the chemical module, and Task 3 is validation and application. We have made significant progress on all three tasks and we are on schedule on both technical and budget. In this report, we will detail our progress on Tasks 1 through 3 for the first six months of the second year of the project.

  10. A NEW GENERATION CHEMICAL FLOODING SIMULATOR

    SciTech Connect

    Gary A. Pope; Kamy Sepehrnoori; Mojdeh Delshad

    2004-05-01

    The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved using state-of-the-art algorithms and computers. Such a simulator is not currently available to the industry. The goal of this proposed research is to develop a new-generation chemical flooding simulator that is capable of efficiently and accurately simulating oil reservoirs with at least a million gridblocks in less than one day on massively parallel computers. Task 1 is the formulation and development of solution scheme, Task 2 is the implementation of the chemical module, and Task 3 is validation and application. We have made significant progress on all three tasks and we are on schedule on both technical and budget. In this report, we will detail our progress on Tasks 1 through 3 for the first half of the third year of the project.

  11. A NEW GENERATION CHEMICAL FLOODING SIMULATOR

    SciTech Connect

    Gary A. Pope; Kamy Sepehrnoori; Mojdeh Delshad

    2002-03-01

    The premise of this research is that a general-purpose reservoir simulator for several improved oil recovery processes can and should be developed so that high-resolution simulations of a variety of very large and difficult problems can be achieved using state-of-the-art computing and computers. Such a simulator is not currently available to the industry. The goal of this proposed research is to develop a new-generation chemical flooding simulator that is capable of efficiently and accurately simulating oil reservoirs with at least a million gridblocks in less than one day on massively parallel computers. Task 1 is the formulation and development of solution scheme, Task 2 is the implementation of the chemical module, and Task 3 is validation and application. We have made significant progress on all three tasks and we are on schedule on both technical and budget. In this report, we will detail our progress on Tasks 1 through 3 for the first six months of the project.

  12. Accurate thermoelastic tensor and acoustic velocities of NaCl

    NASA Astrophysics Data System (ADS)

    Marcondes, Michel L.; Shukla, Gaurav; da Silveira, Pedro; Wentzcovitch, Renata M.

    2015-12-01

    Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.

  13. Accurate thermoelastic tensor and acoustic velocities of NaCl

    SciTech Connect

    Marcondes, Michel L.; Shukla, Gaurav; Silveira, Pedro da; Wentzcovitch, Renata M.

    2015-12-15

    Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.

  14. SG oils

    SciTech Connect

    Chamberlin, W.

    1988-01-01

    Automobile manufacturers worldwide have targeted improved vehicle quality as a major goal. Engine oil quality is one component in the quest for an improved quality image. Engine design changes have imposed increased stresses on engine oils. API SG oils will provide a margin of protection to the engine against sludge and varnish deposit formation and valve train wear.

  15. Development of a Standalone Thermal Wellbore Simulator

    NASA Astrophysics Data System (ADS)

    Xiong, Wanqiang

    With continuous developments of various different sophisticated wells in the petroleum industry, wellbore modeling and simulation have increasingly received more attention. Especially in unconventional oil and gas recovery processes, there is a growing demand for more accurate wellbore modeling. Despite notable advancements made in wellbore modeling, none of the existing wellbore simulators has been as successful as reservoir simulators such as Eclipse and CMG's and further research works on handling issues such as accurate heat loss modeling and multi-tubing wellbore modeling are really necessary. A series of mathematical equations including main governing equations, auxiliary equations, PVT equations, thermodynamic equations, drift-flux model equations, and wellbore heat loss calculation equations are collected and screened from publications. Based on these modeling equations, workflows for wellbore simulation and software development are proposed. Research works are conducted in key steps for developing a wellbore simulator: discretization, a grid system, a solution method, a linear equation solver, and computer language. A standalone thermal wellbore simulator is developed by using standard C++ language. This wellbore simulator can simulate single-phase injection and production, two-phase steam injection and two-phase oil and water production. By implementing a multi-part scheme which divides a wellbore with sophisticated configuration into several relative simple simulation running units, this simulator can handle different complex wellbores: wellbore with multistage casings, horizontal wells, multilateral wells and double tubing. In pursuance of improved accuracy of heat loss calculations to surrounding formations, a semi-numerical method is proposed and a series of FLUENT simulations have been conducted in this study. This semi-numerical method involves extending the 2D formation heat transfer simulation to include a casing wall and cement and adopting new

  16. International Oil Supplies and Demands

    SciTech Connect

    Not Available

    1991-09-01

    The eleventh Energy Modeling Forum (EMF) working group met four times over the 1989--90 period to compare alternative perspectives on international oil supplies and demands through 2010 and to discuss how alternative supply and demand trends influence the world's dependence upon Middle Eastern oil. Proprietors of eleven economic models of the world oil market used their respective models to simulate a dozen scenarios using standardized assumptions. From its inception, the study was not designed to focus on the short-run impacts of disruptions on oil markets. Nor did the working group attempt to provide a forecast or just a single view of the likely future path for oil prices. The model results guided the group's thinking about many important longer-run market relationships and helped to identify differences of opinion about future oil supplies, demands, and dependence.

  17. International Oil Supplies and Demands

    SciTech Connect

    Not Available

    1992-04-01

    The eleventh Energy Modeling Forum (EMF) working group met four times over the 1989--1990 period to compare alternative perspectives on international oil supplies and demands through 2010 and to discuss how alternative supply and demand trends influence the world's dependence upon Middle Eastern oil. Proprietors of eleven economic models of the world oil market used their respective models to simulate a dozen scenarios using standardized assumptions. From its inception, the study was not designed to focus on the short-run impacts of disruptions on oil markets. Nor did the working group attempt to provide a forecast or just a single view of the likely future path for oil prices. The model results guided the group's thinking about many important longer-run market relationships and helped to identify differences of opinion about future oil supplies, demands, and dependence.

  18. A Monte Carlo simulation method for the assessment of undiscovered, conventional oil and gas: Chapter 26 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

    USGS Publications Warehouse

    Charpentier, Ronald R.; Klett, T.R.

    2007-01-01

    The U.S. Geological Survey has developed two Monte Carlo programs for assessment of undiscovered conventional oil and gas resources. EMCEE (for Energy Monte Carlo) and Emc2 (for Energy Monte Carlo program 2) are programs that calculate probabilistic estimates of undiscovered resources based on input distributions for numbers and sizes of undiscovered fields. Emc2 uses specific types of distributions for the input, whereas EMCEE allows greater flexibility of the input distribution types.

  19. Peppermint oil.

    PubMed

    Kligler, Benjamin; Chaudhary, Sapna

    2007-04-01

    Peppermint leaf and peppermint oil have a long history of use for digestive disorders. Recent evidence suggests that enteric-coated peppermint oil may be effective in relieving some of the symptoms of irritable bowel syndrome. A combination product including peppermint oil and caraway oil seems to be moderately effective in the treatment of non-ulcer dyspepsia. Topical application of peppermint oil may be effective in the treatment of tension headache. Because of its relaxing effects on smooth muscle, peppermint oil given via enema has been modestly effective for relief of colonic spasm in patients undergoing barium enemas. Peppermint oil is well tolerated at the commonly recommended dosage, but it may cause significant adverse effects at higher dosages. PMID:17427617

  20. Extracting Time-Accurate Acceleration Vectors From Nontrivial Accelerometer Arrangements.

    PubMed

    Franck, Jennifer A; Blume, Janet; Crisco, Joseph J; Franck, Christian

    2015-09-01

    Sports-related concussions are of significant concern in many impact sports, and their detection relies on accurate measurements of the head kinematics during impact. Among the most prevalent recording technologies are videography, and more recently, the use of single-axis accelerometers mounted in a helmet, such as the HIT system. Successful extraction of the linear and angular impact accelerations depends on an accurate analysis methodology governed by the equations of motion. Current algorithms are able to estimate the magnitude of acceleration and hit location, but make assumptions about the hit orientation and are often limited in the position and/or orientation of the accelerometers. The newly formulated algorithm presented in this manuscript accurately extracts the full linear and rotational acceleration vectors from a broad arrangement of six single-axis accelerometers directly from the governing set of kinematic equations. The new formulation linearizes the nonlinear centripetal acceleration term with a finite-difference approximation and provides a fast and accurate solution for all six components of acceleration over long time periods (>250 ms). The approximation of the nonlinear centripetal acceleration term provides an accurate computation of the rotational velocity as a function of time and allows for reconstruction of a multiple-impact signal. Furthermore, the algorithm determines the impact location and orientation and can distinguish between glancing, high rotational velocity impacts, or direct impacts through the center of mass. Results are shown for ten simulated impact locations on a headform geometry computed with three different accelerometer configurations in varying degrees of signal noise. Since the algorithm does not require simplifications of the actual impacted geometry, the impact vector, or a specific arrangement of accelerometer orientations, it can be easily applied to many impact investigations in which accurate kinematics need to

  1. Mill profiler machines soft materials accurately

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1966-01-01

    Mill profiler machines bevels, slots, and grooves in soft materials, such as styrofoam phenolic-filled cores, to any desired thickness. A single operator can accurately control cutting depths in contour or straight line work.

  2. Effects of oil and dispersant on formation of marine oil snow and transport of oil hydrocarbons.

    PubMed

    Fu, Jie; Gong, Yanyan; Zhao, Xiao; O'Reilly, S E; Zhao, Dongye

    2014-12-16

    This work explored the formation mechanism of marine oil snow (MOS) and the associated transport of oil hydrocarbons in the presence of a stereotype oil dispersant, Corexit EC9500A. Roller table experiments were carried out to simulate natural marine processes that lead to formation of marine snow. We found that both oil and the dispersant greatly promoted the formation of MOS, and MOS flocs as large as 1.6-2.1 mm (mean diameter) were developed within 3-6 days. Natural suspended solids and indigenous microorganisms play critical roles in the MOS formation. The addition of oil and the dispersant greatly enhanced the bacterial growth and extracellular polymeric substance (EPS) content, resulting in increased flocculation and formation of MOS. The dispersant not only enhanced dissolution of n-alkanes (C9-C40) from oil slicks into the aqueous phase, but facilitated sorption of more oil components onto MOS. The incorporation of oil droplets in MOS resulted in a two-way (rising and sinking) transport of the MOS particles. More lower-molecular-weight (LMW) n-alkanes (C9-C18) were partitioned in MOS than in the aqueous phase in the presence of the dispersant. The information can aid in our understanding of dispersant effects on MOS formation and oil transport following an oil spill event. PMID:25420231

  3. Effects of oil and dispersant on formation of marine oil snow and transport of oil hydrocarbons.

    PubMed

    Fu, Jie; Gong, Yanyan; Zhao, Xiao; O'Reilly, S E; Zhao, Dongye

    2014-12-16

    This work explored the formation mechanism of marine oil snow (MOS) and the associated transport of oil hydrocarbons in the presence of a stereotype oil dispersant, Corexit EC9500A. Roller table experiments were carried out to simulate natural marine processes that lead to formation of marine snow. We found that both oil and the dispersant greatly promoted the formation of MOS, and MOS flocs as large as 1.6-2.1 mm (mean diameter) were developed within 3-6 days. Natural suspended solids and indigenous microorganisms play critical roles in the MOS formation. The addition of oil and the dispersant greatly enhanced the bacterial growth and extracellular polymeric substance (EPS) content, resulting in increased flocculation and formation of MOS. The dispersant not only enhanced dissolution of n-alkanes (C9-C40) from oil slicks into the aqueous phase, but facilitated sorption of more oil components onto MOS. The incorporation of oil droplets in MOS resulted in a two-way (rising and sinking) transport of the MOS particles. More lower-molecular-weight (LMW) n-alkanes (C9-C18) were partitioned in MOS than in the aqueous phase in the presence of the dispersant. The information can aid in our understanding of dispersant effects on MOS formation and oil transport following an oil spill event.

  4. Venezuelan oil

    SciTech Connect

    Martinez, A.R. )

    1989-01-01

    Oil reserves have been known to exist in Venezuela since early historical records, however, it was not until the 20th century that the extensive search for new reserves began. The 1950's marked the height of oil exploration when 200 new oil fields were discovered, as well as over 60{percent} of proven reserves. Venezuela now produces one tone in seven of crude oil consumption and the country's abundant reserves such as the Bolivar Coastal field in the West of the country and the Orinoco Belt field in the East, will ensure it's continuing importance as an oil producer well into the 21st century. This book charts the historical development of Venezuela oil and provides a chronology of all the significant events which have shaped the oil industry of today. It covers all the technical, legal, economic and political factors which have contributed to the evolution of the industry and also gives information on current oil resources and production. Those events significant to the development of the industry, those which were influential in shaping future policy and those which precipitated further action are included. The book provides a source of reference to oil companies, oil economists and petroleum geologists.

  5. Used oil as a fuel oil alternative

    SciTech Connect

    Karaosmanoglu, F.; Beker, U.G.

    1996-09-01

    In this study, the possibility of using used frying oil as a fuel oil alternative has been investigated. The fuel oil analysis tests applied to the reference fuel oil, used frying oil and its blends with fuel oil, were done according to standard test methods. The experimental results indicated that used frying oil and its blends with fuel oil can be proposed as a possible substitute for fuel oil.

  6. Benchmarking accurate spectral phase retrieval of single attosecond pulses

    NASA Astrophysics Data System (ADS)

    Wei, Hui; Le, Anh-Thu; Morishita, Toru; Yu, Chao; Lin, C. D.

    2015-02-01

    A single extreme-ultraviolet (XUV) attosecond pulse or pulse train in the time domain is fully characterized if its spectral amplitude and phase are both determined. The spectral amplitude can be easily obtained from photoionization of simple atoms where accurate photoionization cross sections have been measured from, e.g., synchrotron radiations. To determine the spectral phase, at present the standard method is to carry out XUV photoionization in the presence of a dressing infrared (IR) laser. In this work, we examine the accuracy of current phase retrieval methods (PROOF and iPROOF) where the dressing IR is relatively weak such that photoelectron spectra can be accurately calculated by second-order perturbation theory. We suggest a modified method named swPROOF (scattering wave phase retrieval by omega oscillation filtering) which utilizes accurate one-photon and two-photon dipole transition matrix elements and removes the approximations made in PROOF and iPROOF. We show that the swPROOF method can in general retrieve accurate spectral phase compared to other simpler models that have been suggested. We benchmark the accuracy of these phase retrieval methods through simulating the spectrogram by solving the time-dependent Schrödinger equation numerically using several known single attosecond pulses with a fixed spectral amplitude but different spectral phases.

  7. An Accurate Link Correlation Estimator for Improving Wireless Protocol Performance

    PubMed Central

    Zhao, Zhiwei; Xu, Xianghua; Dong, Wei; Bu, Jiajun

    2015-01-01

    Wireless link correlation has shown significant impact on the performance of various sensor network protocols. Many works have been devoted to exploiting link correlation for protocol improvements. However, the effectiveness of these designs heavily relies on the accuracy of link correlation measurement. In this paper, we investigate state-of-the-art link correlation measurement and analyze the limitations of existing works. We then propose a novel lightweight and accurate link correlation estimation (LACE) approach based on the reasoning of link correlation formation. LACE combines both long-term and short-term link behaviors for link correlation estimation. We implement LACE as a stand-alone interface in TinyOS and incorporate it into both routing and flooding protocols. Simulation and testbed results show that LACE: (1) achieves more accurate and lightweight link correlation measurements than the state-of-the-art work; and (2) greatly improves the performance of protocols exploiting link correlation. PMID:25686314

  8. An accurate link correlation estimator for improving wireless protocol performance.

    PubMed

    Zhao, Zhiwei; Xu, Xianghua; Dong, Wei; Bu, Jiajun

    2015-02-12

    Wireless link correlation has shown significant impact on the performance of various sensor network protocols. Many works have been devoted to exploiting link correlation for protocol improvements. However, the effectiveness of these designs heavily relies on the accuracy of link correlation measurement. In this paper, we investigate state-of-the-art link correlation measurement and analyze the limitations of existing works. We then propose a novel lightweight and accurate link correlation estimation (LACE) approach based on the reasoning of link correlation formation. LACE combines both long-term and short-term link behaviors for link correlation estimation. We implement LACE as a stand-alone interface in TinyOS and incorporate it into both routing and flooding protocols. Simulation and testbed results show that LACE: (1) achieves more accurate and lightweight link correlation measurements than the state-of-the-art work; and (2) greatly improves the performance of protocols exploiting link correlation.

  9. A fast and accurate method for echocardiography strain rate imaging

    NASA Astrophysics Data System (ADS)

    Tavakoli, Vahid; Sahba, Nima; Hajebi, Nima; Nambakhsh, Mohammad Saleh

    2009-02-01

    Recently Strain and strain rate imaging have proved their superiority with respect to classical motion estimation methods in myocardial evaluation as a novel technique for quantitative analysis of myocardial function. Here in this paper, we propose a novel strain rate imaging algorithm using a new optical flow technique which is more rapid and accurate than the previous correlation-based methods. The new method presumes a spatiotemporal constancy of intensity and Magnitude of the image. Moreover the method makes use of the spline moment in a multiresolution approach. Moreover cardiac central point is obtained using a combination of center of mass and endocardial tracking. It is proved that the proposed method helps overcome the intensity variations of ultrasound texture while preserving the ability of motion estimation technique for different motions and orientations. Evaluation is performed on simulated, phantom (a contractile rubber balloon) and real sequences and proves that this technique is more accurate and faster than the previous methods.

  10. Accurate Parameter Estimation for Unbalanced Three-Phase System

    PubMed Central

    Chen, Yuan

    2014-01-01

    Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the α β-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS. PMID:25162056

  11. Accurate adjoint design sensitivities for nano metal optics.

    PubMed

    Hansen, Paul; Hesselink, Lambertus

    2015-09-01

    We present a method for obtaining accurate numerical design sensitivities for metal-optical nanostructures. Adjoint design sensitivity analysis, long used in fluid mechanics and mechanical engineering for both optimization and structural analysis, is beginning to be used for nano-optics design, but it fails for sharp-cornered metal structures because the numerical error in electromagnetic simulations of metal structures is highest at sharp corners. These locations feature strong field enhancement and contribute strongly to design sensitivities. By using high-accuracy FEM calculations and rounding sharp features to a finite radius of curvature we obtain highly-accurate design sensitivities for 3D metal devices. To provide a bridge to the existing literature on adjoint methods in other fields, we derive the sensitivity equations for Maxwell's equations in the PDE framework widely used in fluid mechanics. PMID:26368483

  12. Accurate parameter estimation for unbalanced three-phase system.

    PubMed

    Chen, Yuan; So, Hing Cheung

    2014-01-01

    Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the α β-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS.

  13. Oil gluts and oil tariffs

    SciTech Connect

    Hogan, W.W.

    1982-01-01

    The free market does not provide the level of oil imports that is in the best interest of oil-importing nations. Common sense tells us that the best time to combat the economic power of a cartel is when it is weak, such as during a period of oil glut. The glut conditions still leave us with a large gap between the true cost of oil and the market price. The authors could justify an oil import tariff of 30-40% of the price of oil, or more. Nearly every other consideration, especially the positive effect on the federal budget, reinforces the recommendation for a large import tariff. An analysis in the appendix showing the otpimal tariff at 65-100% suggests that we should impose the largest tariff we can get through the political system. 9 references, 10 tables.

  14. Modified chemiluminescent NO analyzer accurately measures NOX

    NASA Technical Reports Server (NTRS)

    Summers, R. L.

    1978-01-01

    Installation of molybdenum nitric oxide (NO)-to-higher oxides of nitrogen (NOx) converter in chemiluminescent gas analyzer and use of air purge allow accurate measurements of NOx in exhaust gases containing as much as thirty percent carbon monoxide (CO). Measurements using conventional analyzer are highly inaccurate for NOx if as little as five percent CO is present. In modified analyzer, molybdenum has high tolerance to CO, and air purge substantially quenches NOx destruction. In test, modified chemiluminescent analyzer accurately measured NO and NOx concentrations for over 4 months with no denegration in performance.

  15. Antidiabetic oils.

    PubMed

    Berraaouan, Ali; Abid, Sanae; Bnouham, Mohamed

    2013-11-01

    Many studies have demonstrated evidence of the health benefits of natural products. Plant extracts have been tested on a variety of physiological disorders, including diabetes mellitus. Studies have tested aqueous extracts, plant fractions extracts, families of active of compounds, and specific active compounds. In this review, we describe the antidiabetic effects of vegetable oils. Information was collected from ScienceDirect and PubMed databases using the following key words: Diabetes mellitus, Oils, Vegetable oils, Type 1 diabetes, type 2 diabetes, antidiabetic effect, antihyperglycemic, antidiabetic oil. We have compiled approximately ten vegetable oils with including experimental studies that have demonstrated benefits on diabetes mellitus. There are soybean, argan, olive, palm, walnut, black cumin, safflower, Colocynth, Black seed, Rice bran, Cinnamom, and Rocket oils. For each vegetable oil, we investigated on the plant's traditional uses, their pharmacological activities and their antidiabetic effects. It seems that many vegetable oils are really interesting and can be used in the improvement of human health, particularly, to prevent or to treat diabetes mellitus complications.

  16. Simulation Software

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Various NASA Small Business Innovation Research grants from Marshall Space Flight Center, Langley Research Center and Ames Research Center were used to develop the 'kernel' of COMCO's modeling and simulation software, the PHLEX finite element code. NASA needed it to model designs of flight vehicles; one of many customized commercial applications is UNISIM, a PHLEX-based code for analyzing underground flows in oil reservoirs for Texaco, Inc. COMCO's products simulate a computational mechanics problem, estimate the solution's error and produce the optimal hp-adapted mesh for the accuracy the user chooses. The system is also used as a research or training tool in universities and in mechanical design in industrial corporations.

  17. Hydrodynamic factors affecting the persistence of the Exxon Valdez oil in a shallow bedrock beach

    NASA Astrophysics Data System (ADS)

    Xia, Yuqiang; Li, Hailong; Boufadel, Michel C.; Sharifi, Youness

    2010-10-01

    We report a field study and numerical modeling of multicomponent flow in a tidal gravel beach in Knight Island, Prince William Sound, Alaska, where oil from the 1989 Exxon Valdez oil spill persisted. Field measurements of water table, salinity, and tracer (lithium) concentration were obtained for around a week during the summer of 2008. The numerical model MARUN was used to simulate the field observations. On the basis of field experiments and numerical simulations, the beach was identified to have a two-layered hydraulic structure: a high-permeability surface layer underlain by a low-permeability lower layer. The hydraulic conductivity was found to be 5 × 10-2 m s-1 for the surface layer and 7 × 10-6 m s-1 for the lower layer. The simulations reproduced the observed water table, salinity, and lithium concentrations accurately. The small flow entering the beach from the land side resulted in a beach water table dropping below the interface of the two layers. This seems to be the major reason for the presence of oil in the lower layer. The exchange flow between the beach and the sea due to tidal influence was ˜2.12 m3 d-1 m-1. The patterns of inflow and outflow rates showed that the maximum seawater-groundwater exchange occurred in the middle to high intertidal zone, which explains the persistence of oil in the lower intertidal zone. To explore bioremediation of the beach with nutrient amendment, a numerical simulation of nutrient application on the beach surface was conducted, where the applied nutrient concentration was 5,000 mg L-1. The results showed that the nutrient concentration remaining in oiled areas after a week was larger than 50 mg L-1, which is larger than that needed for maximum microbial growth (2-10 mg L-1). This implies that the bioremediation via nutrient application on the beach surface could be adopted if nutrients were the only limiting factor.

  18. Aperture taper determination for the half-scale accurate antenna reflector

    NASA Technical Reports Server (NTRS)

    Lambert, Kevin M.

    1990-01-01

    A simulation is described of a proposed microwave reflectance measurement in which the half scale reflector is used in a compact range type of application. The simulation is used to determine an acceptable aperture taper for the reflector which will allow for accurate measurements. Information on the taper is used in the design of a feed for the reflector.

  19. Can Appraisers Rate Work Performance Accurately?

    ERIC Educational Resources Information Center

    Hedge, Jerry W.; Laue, Frances J.

    The ability of individuals to make accurate judgments about others is examined and literature on this subject is reviewed. A wide variety of situational factors affects the appraisal of performance. It is generally accepted that the purpose of the appraisal influences the accuracy of the appraiser. The instrumentation, or tools, available to the…

  20. Accurate pointing of tungsten welding electrodes

    NASA Technical Reports Server (NTRS)

    Ziegelmeier, P.

    1971-01-01

    Thoriated-tungsten is pointed accurately and quickly by using sodium nitrite. Point produced is smooth and no effort is necessary to hold the tungsten rod concentric. The chemically produced point can be used several times longer than ground points. This method reduces time and cost of preparing tungsten electrodes.

  1. Peak Oil, Peak Coal and Climate Change

    NASA Astrophysics Data System (ADS)

    Murray, J. W.

    2009-05-01

    Research on future climate change is driven by the family of scenarios developed for the IPCC assessment reports. These scenarios create projections of future energy demand using different story lines consisting of government policies, population projections, and economic models. None of these scenarios consider resources to be limiting. In many of these scenarios oil production is still increasing to 2100. Resource limitation (in a geological sense) is a real possibility that needs more serious consideration. The concept of 'Peak Oil' has been discussed since M. King Hubbert proposed in 1956 that US oil production would peak in 1970. His prediction was accurate. This concept is about production rate not reserves. For many oil producing countries (and all OPEC countries) reserves are closely guarded state secrets and appear to be overstated. Claims that the reserves are 'proven' cannot be independently verified. Hubbert's Linearization Model can be used to predict when half the ultimate oil will be produced and what the ultimate total cumulative production (Qt) will be. US oil production can be used as an example. This conceptual model shows that 90% of the ultimate US oil production (Qt = 225 billion barrels) will have occurred by 2011. This approach can then be used to suggest that total global production will be about 2200 billion barrels and that the half way point will be reached by about 2010. This amount is about 5 to 7 times less than assumed by the IPCC scenarios. The decline of Non-OPEC oil production appears to have started in 2004. Of the OPEC countries, only Saudi Arabia may have spare capacity, but even that is uncertain, because of lack of data transparency. The concept of 'Peak Coal' is more controversial, but even the US National Academy Report in 2007 concluded only a small fraction of previously estimated reserves in the US are actually minable reserves and that US reserves should be reassessed using modern methods. British coal production can be

  2. Oil spills abatement: factors affecting oil uptake by cellulosic fibers.

    PubMed

    Payne, Katharine C; Jackson, Colby D; Aizpurua, Carlos E; Rojas, Orlando J; Hubbe, Martin A

    2012-07-17

    Wood-derived cellulosic fibers prepared in different ways were successfully employed to absorb simulated crude oil, demonstrating their possible use as absorbents in the case of oil spills. When dry fibers were used, the highest sorption capacity (six parts of oil per unit mass of fiber) was shown by bleached softwood kraft fibers, compared to hardwood bleached kraft and softwood chemithermomechanical pulp(CTMP) fibers. Increased refining of CTMP fibers decreased their oil uptake capacity. When the fibers were soaked in water before exposure to the oil, the ability of the unmodified kraft fibers to sorb oil was markedly reduced, whereas the wet CTMP fibers were generally more effective than the wet kraft fibers. Predeposition of lignin onto the surfaces of the bleached kraft fibers improved their ability to take up oil when wet. Superior ability to sorb oil in the wet state was achieved by pretreating the kraft fibers with a hydrophobic sizing agent, alkenylsuccinic anhydride (ASA). Contact angle tests on a model cellulose surface showed that some of the sorption results onto wetted fibers could be attributed to the more hydrophobic nature of the fibers after treatment with either lignin or ASA.

  3. Accuracy improvement of the radar backscatter simulation from sea surface covered by oil slick using fetch-dependent waveheight spectrum: Comparison with the 2007 Heibei Spirit Case in the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Ho; Yang, Chan-Su; Ouchi, Kazuo

    2016-03-01

    In this paper, results are presented on the comparison of X-band radar backscattering coefficient (RBC) from an oilcovered sea surface that features the Elfouhaily and Durden-Vesecky waveheight spectra. The Durden-Vesecky spectrum applies to a fully-developed sea, while the Elfouhaily spectrum accounts for the fetch of arbitrary length. Using these two waveheight spectra, a one-dimensional random rough surface is simulated by the Monte Carlo method, and the method of moments (MoM) is applied to yield the RBC. Comparison of the results with TerraSAR-X synthetic aperture radar (SAR) data acquired over the coastal waters polluted by the Hebei Spirit oil tanker shows that the Elfouhaily spectrum yields better agreement than the Durden-Vesecky spectrum for the fully-developed sea, and that the fetch-dependent Elfouhaily spectrum improves the agreement with SAR data in comparison with the fetch-independent spectrum for the fully developed sea. A possible application to estimate the amount of spilled oil is also suggested.

  4. [Rapid discriminating hogwash oil and edible vegetable oil using near infrared optical fiber spectrometer technique].

    PubMed

    Zhang, Bing-Fang; Yuan, Li-Bo; Kong, Qing-Ming; Shen, Wei-Zheng; Zhang, Bing-Xiu; Liu, Cheng-Hai

    2014-10-01

    In the present study, a new method using near infrared spectroscopy combined with optical fiber sensing technology was applied to the analysis of hogwash oil in blended oil. The 50 samples were a blend of frying oil and "nine three" soybean oil according to a certain volume ratio. The near infrared transmission spectroscopies were collected and the quantitative analysis model of frying oil was established by partial least squares (PLS) and BP artificial neural network The coefficients of determina- tion of calibration sets were 0.908 and 0.934 respectively. The coefficients of determination of validation sets were 0.961 and 0.952, the root mean square error of calibrations (RMSEC) was 0.184 and 0.136, and the root mean square error of predictions (RMSEP) was all 0.111 6. They conform to the model application requirement. At the same time, frying oil and qualified edible oil were identified with the principal component analysis (PCA), and the accurate rate was 100%. The experiment proved that near infrared spectral technology not only can quickly and accurately identify hogwash oil, but also can quantitatively detect hog- wash oil. This method has a wide application prospect in the detection of oil.

  5. Throwing light on petroleum: simulated exposure of crude oil to sunlight and characterization using atmospheric pressure photoionization fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Griffiths, Matthew T; Da Campo, Raffaello; O'Connor, Peter B; Barrow, Mark P

    2014-01-01

    The change in profile of crude oil following a release into the environment is a topic of significant interest, and there is a need to develop analytical methodologies for understanding natural processes which affect related complex mixture profiles. One such process is the exposure to sunlight. In the following investigation, three oil samples were studied: one served as a control, a second was subjected to irradiation by an ultraviolet lamp, and a third sample was irradiated by a SoLux light source which closely models the solar emission profile. The usage of the SoLux light source represents a new method which enables a controlled experiment to mimic the effects of sunlight upon the sample. Atmospheric pressure photoionization was selected as the primary ionization method due to the ability to ionize a broad range of compounds, including low polarity components which could not be observed using electrospray ionization. During a test of sample preparation methods, the addition of a protic cosolvent to the sample solutions was shown to broaden the range of heteroatom-containing components observed. Following characterization, it was found that the polyaromatic hydrocarbons did not change in profile, while compounds containing a heteroatom exhibited a tendency to oxidize following photoirradiation. Sulfur-containing compounds with a low number of double bond equivalents were among the most reactive components of the complex mixture. The photooxidation of compounds in petroleum, following exposure to sunlight, is expected to have significance with regards to solubility and potential toxicity.

  6. OPTICAL FIBER SENSOR TECHNOLOGIES FOR EFFICIENT AND ECONOMICAL OIL RECOVERY

    SciTech Connect

    Anbo Wang; Kristie L. Cooper; Gary R. Pickrell

    2003-06-01

    Efficient recovery of petroleum reserves from existing oil wells has been proven to be difficult due to the lack of robust instrumentation that can accurately and reliably monitor processes in the downhole environment. Commercially available sensors for measurement of pressure, temperature, and fluid flow exhibit shortened lifetimes in the harsh downhole conditions, which are characterized by high pressures (up to 20 kpsi), temperatures up to 250 C, and exposure to chemically reactive fluids. Development of robust sensors that deliver continuous, real-time data on reservoir performance and petroleum flow pathways will facilitate application of advanced recovery technologies, including horizontal and multilateral wells. This is the final report for the four-year program ''Optical Fiber Sensor Technologies for Efficient and Economical Oil Recovery'', funded by the National Petroleum Technology Office of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech from October 1, 1999 to March 31, 2003. The main objective of this research program was to develop cost-effective, reliable optical fiber sensor instrumentation for real-time monitoring of various key parameters crucial to efficient and economical oil production. During the program, optical fiber sensors were demonstrated for the measurement of temperature, pressure, flow, and acoustic waves, including three successful field tests in the Chevron/Texaco oil fields in Coalinga, California, and at the world-class oil flow simulation facilities in Tulsa, Oklahoma. Research efforts included the design and fabrication of sensor probes, development of signal processing algorithms, construction of test systems, development and testing of strategies for the protection of optical fibers and sensors in the downhole environment, development of remote monitoring capabilities allowing real-time monitoring of the field

  7. Quantitation of microbial products and their effectiveness in enhanced oil recovery. Final report

    SciTech Connect

    Zhang, X.; Knapp, R.M.; McInerney, M.J.

    1995-02-01

    A three-dimensional, three-phase, multiple-component numerical simulator was developed to investigate transport and growth of microorganisms in porous media and the impacts of microbial activities on oil recovery. The microbial activities modeled in this study included: (1) growth, retention, chemotaxis, and end product inhibition of growth, (2) the formation of metabolic products, and (3) the consumption of nutrients. Major mechanisms for microbial enhanced oil recovery (MEOR) processes were modeled as follows: (1) improvement in sweep efficiency of a displacement process due to in situ plugging of highly-permeable production zones by cell mass or due to improved mobility control achieved by increasing the viscosity of the displacing fluid with a biopolymer, and (2) solubilization and mobilization of residual oil in porous media due to the reduction of the interfacial tension between oleic and aqueous phases by the production of a biosurfactant. The numerical solutions for mathematical models involved two steps. The distributions of pressure and phase saturations were solved from continuity equations and Darcy flow velocities for the aqueous phase were computed. This was followed by the solution of convection-dispersion equations for individual components. Numerical solutions from the proposed model were compared to results obtained from analytical equations, commercial simulators, and laboratory experiments. The comparison indicated that the model accurately quantified microbial transport and metabolism in porous media, and predicted additional crude oil recovery due to microbial processes. 50 refs., 41 figs., 26 tabs.

  8. Oil shale

    SciTech Connect

    Knutson, C.F.

    1981-10-01

    Significant oil shale development activities are taking place in the Piceance basin in northwestern Colorado and the Uinta basin in northeastern Utah. About 377,000 bbl/d of oil production capacity is in the planning or construction phase in the Piceance basin and about 240,000 bbl/d capacity in the Uinta basin. Completion of these projects will depend upon the political, environmental, and technical feasibility. Additional oil shale development of about 80,000 bbl/d is being planned for Brazil and Morocco. 3 figures.

  9. Feedback about More Accurate versus Less Accurate Trials: Differential Effects on Self-Confidence and Activation

    ERIC Educational Resources Information Center

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-01-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected by feedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On Day 1, participants performed a golf putting task under one of…

  10. Application of an enhanced discrete element method to oil and gas drilling processes

    NASA Astrophysics Data System (ADS)

    Ubach, Pere Andreu; Arrufat, Ferran; Ring, Lev; Gandikota, Raju; Zárate, Francisco; Oñate, Eugenio

    2016-03-01

    The authors present results on the use of the discrete element method (DEM) for the simulation of drilling processes typical in the oil and gas exploration industry. The numerical method uses advanced DEM techniques using a local definition of the DEM parameters and combined FEM-DEM procedures. This paper presents a step-by-step procedure to build a DEM model for analysis of the soil region coupled to a FEM model for discretizing the drilling tool that reproduces the drilling mechanics of a particular drill bit. A parametric study has been performed to determine the model parameters in order to maintain accurate solutions with reduced computational cost.

  11. Feedback about more accurate versus less accurate trials: differential effects on self-confidence and activation.

    PubMed

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-06-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected byfeedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On day 1, participants performed a golf putting task under one of two conditions: one group received feedback on the most accurate trials, whereas another group received feedback on the least accurate trials. On day 2, participants completed an anxiety questionnaire and performed a retention test. Shin conductance level, as a measure of arousal, was determined. The results indicated that feedback about more accurate trials resulted in more effective learning as well as increased self-confidence. Also, activation was a predictor of performance. PMID:22808705

  12. Towards Accurate Molecular Modeling of Plastic Bonded Explosives

    NASA Astrophysics Data System (ADS)

    Chantawansri, T. L.; Andzelm, J.; Taylor, D.; Byrd, E.; Rice, B.

    2010-03-01

    There is substantial interest in identifying the controlling factors that influence the susceptibility of polymer bonded explosives (PBXs) to accidental initiation. Numerous Molecular Dynamics (MD) simulations of PBXs using the COMPASS force field have been reported in recent years, where the validity of the force field in modeling the solid EM fill has been judged solely on its ability to reproduce lattice parameters, which is an insufficient metric. Performance of the COMPASS force field in modeling EMs and the polymeric binder has been assessed by calculating structural, thermal, and mechanical properties, where only fair agreement with experimental data is obtained. We performed MD simulations using the COMPASS force field for the polymer binder hydroxyl-terminated polybutadiene and five EMs: cyclotrimethylenetrinitramine, 1,3,5,7-tetranitro-1,3,5,7-tetra-azacyclo-octane, 2,4,6,8,10,12-hexantirohexaazazisowurzitane, 2,4,6-trinitro-1,3,5-benzenetriamine, and pentaerythritol tetranitate. Predicted EM crystallographic and molecular structural parameters, as well as calculated properties for the binder will be compared with experimental results for different simulation conditions. We also present novel simulation protocols, which improve agreement between experimental and computation results thus leading to the accurate modeling of PBXs.

  13. SPECTROPOLARIMETRICALLY ACCURATE MAGNETOHYDROSTATIC SUNSPOT MODEL FOR FORWARD MODELING IN HELIOSEISMOLOGY

    SciTech Connect

    Przybylski, D.; Shelyag, S.; Cally, P. S.

    2015-07-01

    We present a technique to construct a spectropolarimetrically accurate magnetohydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the constructed model we perform a simulation of acoustic wave propagation, conversion, and absorption in the solar interior and photosphere with the sunspot embedded into it. With the 6173 Å magnetically sensitive photospheric absorption line of neutral iron, we calculate observable quantities such as continuum intensities, Doppler velocities, as well as the full Stokes vector for the simulation at various positions at the solar disk, and analyze the influence of non-locality of radiative transport in the solar photosphere on helioseismic measurements. Bisector shapes were used to perform multi-height observations. The differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterized. An increase in acoustic power in the simulated observations of the sunspot umbra away from the solar disk center was confirmed as the slow magnetoacoustic wave.

  14. Two highly accurate methods for pitch calibration

    NASA Astrophysics Data System (ADS)

    Kniel, K.; Härtig, F.; Osawa, S.; Sato, O.

    2009-11-01

    Among profiles, helix and tooth thickness pitch is one of the most important parameters of an involute gear measurement evaluation. In principle, coordinate measuring machines (CMM) and CNC-controlled gear measuring machines as a variant of a CMM are suited for these kinds of gear measurements. Now the Japan National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and the German national metrology institute the Physikalisch-Technische Bundesanstalt (PTB) have each developed independently highly accurate pitch calibration methods applicable to CMM or gear measuring machines. Both calibration methods are based on the so-called closure technique which allows the separation of the systematic errors of the measurement device and the errors of the gear. For the verification of both calibration methods, NMIJ/AIST and PTB performed measurements on a specially designed pitch artifact. The comparison of the results shows that both methods can be used for highly accurate calibrations of pitch standards.

  15. Accurate guitar tuning by cochlear implant musicians.

    PubMed

    Lu, Thomas; Huang, Juan; Zeng, Fan-Gang

    2014-01-01

    Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼ 30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task. PMID:24651081

  16. Accurate Guitar Tuning by Cochlear Implant Musicians

    PubMed Central

    Lu, Thomas; Huang, Juan; Zeng, Fan-Gang

    2014-01-01

    Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task. PMID:24651081

  17. Preparation and accurate measurement of pure ozone.

    PubMed

    Janssen, Christof; Simone, Daniela; Guinet, Mickaël

    2011-03-01

    Preparation of high purity ozone as well as precise and accurate measurement of its pressure are metrological requirements that are difficult to meet due to ozone decomposition occurring in pressure sensors. The most stable and precise transducer heads are heated and, therefore, prone to accelerated ozone decomposition, limiting measurement accuracy and compromising purity. Here, we describe a vacuum system and a method for ozone production, suitable to accurately determine the pressure of pure ozone by avoiding the problem of decomposition. We use an inert gas in a particularly designed buffer volume and can thus achieve high measurement accuracy and negligible degradation of ozone with purities of 99.8% or better. The high degree of purity is ensured by comprehensive compositional analyses of ozone samples. The method may also be applied to other reactive gases. PMID:21456766

  18. Accurate guitar tuning by cochlear implant musicians.

    PubMed

    Lu, Thomas; Huang, Juan; Zeng, Fan-Gang

    2014-01-01

    Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼ 30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task.

  19. Accurate modeling of parallel scientific computations

    NASA Technical Reports Server (NTRS)

    Nicol, David M.; Townsend, James C.

    1988-01-01

    Scientific codes are usually parallelized by partitioning a grid among processors. To achieve top performance it is necessary to partition the grid so as to balance workload and minimize communication/synchronization costs. This problem is particularly acute when the grid is irregular, changes over the course of the computation, and is not known until load time. Critical mapping and remapping decisions rest on the ability to accurately predict performance, given a description of a grid and its partition. This paper discusses one approach to this problem, and illustrates its use on a one-dimensional fluids code. The models constructed are shown to be accurate, and are used to find optimal remapping schedules.

  20. Line gas sampling system ensures accurate analysis

    SciTech Connect

    Not Available

    1992-06-01

    Tremendous changes in the natural gas business have resulted in new approaches to the way natural gas is measured. Electronic flow measurement has altered the business forever, with developments in instrumentation and a new sensitivity to the importance of proper natural gas sampling techniques. This paper reports that YZ Industries Inc., Snyder, Texas, combined its 40 years of sampling experience with the latest in microprocessor-based technology to develop the KynaPak 2000 series, the first on-line natural gas sampling system that is both compact and extremely accurate. This means the composition of the sampled gas must be representative of the whole and related to flow. If so, relative measurement and sampling techniques are married, gas volumes are accurately accounted for and adjustments to composition can be made.

  1. Accurate mask model for advanced nodes

    NASA Astrophysics Data System (ADS)

    Zine El Abidine, Nacer; Sundermann, Frank; Yesilada, Emek; Ndiaye, El Hadji Omar; Mishra, Kushlendra; Paninjath, Sankaranarayanan; Bork, Ingo; Buck, Peter; Toublan, Olivier; Schanen, Isabelle

    2014-07-01

    Standard OPC models consist of a physical optical model and an empirical resist model. The resist model compensates the optical model imprecision on top of modeling resist development. The optical model imprecision may result from mask topography effects and real mask information including mask ebeam writing and mask process contributions. For advanced technology nodes, significant progress has been made to model mask topography to improve optical model accuracy. However, mask information is difficult to decorrelate from standard OPC model. Our goal is to establish an accurate mask model through a dedicated calibration exercise. In this paper, we present a flow to calibrate an accurate mask enabling its implementation. The study covers the different effects that should be embedded in the mask model as well as the experiment required to model them.

  2. Calculating model for equivalent consumption efficiency in polarization measurement system of oil-spilled on the sea

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Qian, Weixian; Lu, Dongming; Lu, Yingcheng

    2016-07-01

    As a new analytical method to identify oil spill on sea, the main effect of polarization measurement system is the scattering polarization information of different measured parts. This paper observed the polarization characteristic of oil film and seawater, and analyzed the transmission path of polarized light in the samples. Combined with Fresnel formula and law of Beer, the path of polarized light was divided into three parts, and the light propagation between the molecules was analyzed in detail. The results were affected by the capacity to change the polarization state. In order to quantify the equivalence, we defined an equivalent consumption efficiency (ECE). The ECE describes the ability of the molecules to weaken the polarization attribute of incident light. Then according to the polarization information in Mueller matrix, we inferred that the oil film and seawater had different polarization characteristics. In order to verify the correctness of the model, we applied it to detect the actual oil spill on sea in the case of simulated sunlight finally. Research indicated that the propagation path of polarization light was in connection with the molecular structure and interactions of medium. Under the different measuring angles, the ECE of oil film and seawater have both differences and regularities, the experimental results indicated that it can be used for rapid detection of oil spill on sea, and the data is accurate and reliable.

  3. Accurate maser positions for MALT-45

    NASA Astrophysics Data System (ADS)

    Jordan, Christopher; Bains, Indra; Voronkov, Maxim; Lo, Nadia; Jones, Paul; Muller, Erik; Cunningham, Maria; Burton, Michael; Brooks, Kate; Green, James; Fuller, Gary; Barnes, Peter; Ellingsen, Simon; Urquhart, James; Morgan, Larry; Rowell, Gavin; Walsh, Andrew; Loenen, Edo; Baan, Willem; Hill, Tracey; Purcell, Cormac; Breen, Shari; Peretto, Nicolas; Jackson, James; Lowe, Vicki; Longmore, Steven

    2013-10-01

    MALT-45 is an untargeted survey, mapping the Galactic plane in CS (1-0), Class I methanol masers, SiO masers and thermal emission, and high frequency continuum emission. After obtaining images from the survey, a number of masers were detected, but without accurate positions. This project seeks to resolve each maser and its environment, with the ultimate goal of placing the Class I methanol maser into a timeline of high mass star formation.

  4. Accurate maser positions for MALT-45

    NASA Astrophysics Data System (ADS)

    Jordan, Christopher; Bains, Indra; Voronkov, Maxim; Lo, Nadia; Jones, Paul; Muller, Erik; Cunningham, Maria; Burton, Michael; Brooks, Kate; Green, James; Fuller, Gary; Barnes, Peter; Ellingsen, Simon; Urquhart, James; Morgan, Larry; Rowell, Gavin; Walsh, Andrew; Loenen, Edo; Baan, Willem; Hill, Tracey; Purcell, Cormac; Breen, Shari; Peretto, Nicolas; Jackson, James; Lowe, Vicki; Longmore, Steven

    2013-04-01

    MALT-45 is an untargeted survey, mapping the Galactic plane in CS (1-0), Class I methanol masers, SiO masers and thermal emission, and high frequency continuum emission. After obtaining images from the survey, a number of masers were detected, but without accurate positions. This project seeks to resolve each maser and its environment, with the ultimate goal of placing the Class I methanol maser into a timeline of high mass star formation.

  5. Accurate Molecular Polarizabilities Based on Continuum Electrostatics

    PubMed Central

    Truchon, Jean-François; Nicholls, Anthony; Iftimie, Radu I.; Roux, Benoît; Bayly, Christopher I.

    2013-01-01

    A novel approach for representing the intramolecular polarizability as a continuum dielectric is introduced to account for molecular electronic polarization. It is shown, using a finite-difference solution to the Poisson equation, that the Electronic Polarization from Internal Continuum (EPIC) model yields accurate gas-phase molecular polarizability tensors for a test set of 98 challenging molecules composed of heteroaromatics, alkanes and diatomics. The electronic polarization originates from a high intramolecular dielectric that produces polarizabilities consistent with B3LYP/aug-cc-pVTZ and experimental values when surrounded by vacuum dielectric. In contrast to other approaches to model electronic polarization, this simple model avoids the polarizability catastrophe and accurately calculates molecular anisotropy with the use of very few fitted parameters and without resorting to auxiliary sites or anisotropic atomic centers. On average, the unsigned error in the average polarizability and anisotropy compared to B3LYP are 2% and 5%, respectively. The correlation between the polarizability components from B3LYP and this approach lead to a R2 of 0.990 and a slope of 0.999. Even the F2 anisotropy, shown to be a difficult case for existing polarizability models, can be reproduced within 2% error. In addition to providing new parameters for a rapid method directly applicable to the calculation of polarizabilities, this work extends the widely used Poisson equation to areas where accurate molecular polarizabilities matter. PMID:23646034

  6. Diesel oil

    MedlinePlus

    Various hydrocarbons ... Empyema Many of the most dangerous effects of hydrocarbon (such as diesel oil) poisoning are due to ... PA: Elsevier Saunders; 2016:chap 75. Lee DC. Hydrocarbons. In: Marx JA, Hockberger RS, Walls RM, et ...

  7. Peanut Oil

    MedlinePlus

    ... are pregnant or breast-feeding. Allergy to peanuts, soybeans, and related plants: Peanut oil can cause serious ... reactions in people who are allergic to peanuts, soybeans, and other members of the Fabaceae plant family.

  8. Coconut Oil

    MedlinePlus

    ... chronic fatigue, Crohn's disease, irritable bowel syndrome (IBS), Alzheimer's disease, quality of life in people with breast cancer, thyroid conditions, energy, and boosting the immune system. Despite coconut oil's high calorie and saturated fat ...

  9. On the possible long-term fate of oil released in the deepwater horizon incident: estimated by ensembles of dye release simulations

    SciTech Connect

    Maltrud, Mathew E.; Peacock, Synte L.; Visbeck, Martin

    2010-08-01

    We have conducted an ensemble of 20 simulations using a high-resolution global ocean model in which dye was continuously injected at the site of the Deepwater Horizon drilling rig for two months. We then extended these simulations for another four months to track the dispersal of the dye in the model. We have also performed five simulations in which dye was continuously injected at the site of the spill for four months and then run out to one year from the initial spill date. The experiments can elucidate the time and space scales of dispersal of polluted waters and also give a quantitative estimate of dilution rate, ignoring any sink terms such as chemical or biological degradation.

  10. High Frequency QRS ECG Accurately Detects Cardiomyopathy

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds

    2005-01-01

    High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing

  11. Modeling and simulating critical infrastructures and their interdependencies.

    SciTech Connect

    Rinaldi, Steven M.

    2003-07-01

    Our national security, economic prosperity, and national well-being are dependent upon a set of highly interdependent critical infrastructures. Examples of these infrastructures include the national electrical grid, oil and natural gas systems, telecommunication and information networks, transportation networks, water systems, and banking and financial systems. Given the importance of their reliable and secure operations, understanding the behavior of these infrastructures - particularly when stressed or under attack - is crucial. Models and simulations can provide considerable insight into the complex nature of their behaviors and operational characteristics. These models and simulations must include interdependencies among infrastructures if they are to provide accurate representations of infrastructure characteristics and operations. A number of modeling and simulation approaches under development today directly address interdependencies and offer considerable insight into the operational and behavioral characteristics of critical infrastructures.

  12. Simulation of diurnal thermal energy storage systems: Preliminary results

    SciTech Connect

    Katipamula, S.; Somasundaram, S.; Williams, H.R.

    1994-12-01

    This report describes the results of a simulation of thermal energy storage (TES) integrated with a simple-cycle gas turbine cogeneration system. Integrating TES with cogeneration can serve the electrical and thermal loads independently while firing all fuel in the gas turbine. The detailed engineering and economic feasibility of diurnal TES systems integrated with cogeneration systems has been described in two previous PNL reports. The objective of this study was to lay the ground work for optimization of the TES system designs using a simulation tool called TRNSYS (TRaNsient SYstem Simulation). TRNSYS is a transient simulation program with a sequential-modular structure developed at the Solar Energy Laboratory, University of Wisconsin-Madison. The two TES systems selected for the base-case simulations were: (1) a one-tank storage model to represent the oil/rock TES system, and (2) a two-tank storage model to represent the molten nitrate salt TES system. Results of the study clearly indicate that an engineering optimization of the TES system using TRNSYS is possible. The one-tank stratified oil/rock storage model described here is a good starting point for parametric studies of a TES system. Further developments to the TRNSYS library of available models (economizer, evaporator, gas turbine, etc.) are recommended so that the phase-change processes is accurately treated.

  13. Simulation of diurnal thermal energy storage systems: Preliminary results

    NASA Astrophysics Data System (ADS)

    Katipamula, S.; Somasundaram, S.; Williams, H. R.

    1994-12-01

    This report describes the results of a simulation of thermal energy storage (TES) integrated with a simple-cycle gas turbine cogeneration system. Integrating TES with cogeneration can serve the electrical and thermal loads independently while firing all fuel in the gas turbine. The detailed engineering and economic feasibility of diurnal TES systems integrated with cogeneration systems has been described in two previous PNL reports. The objective of this study was to lay the ground work for optimization of the TES system designs using a simulation tool called TRNSYS (TRaNsient SYstem Simulation). TRNSYS is a transient simulation program with a sequential-modular structure developed at the Solar Energy Laboratory, University of Wisconsin-Madison. The two TES systems selected for the base-case simulations were: (1) a one-tank storage model to represent the oil/rock TES system; and (2) a two-tank storage model to represent the molten nitrate salt TES system. Results of the study clearly indicate that an engineering optimization of the TES system using TRNSYS is possible. The one-tank stratified oil/rock storage model described here is a good starting point for parametric studies of a TES system. Further developments to the TRNSYS library of available models (economizer, evaporator, gas turbine, etc.) are recommended so that the phase-change processes is accurately treated.

  14. Numerical modelling for real-time forecasting of marine oil pollution and hazard assessment

    NASA Astrophysics Data System (ADS)

    De Dominicis, Michela; Pinardi, Nadia; Bruciaferri, Diego; Liubartseva, Svitlana

    2015-04-01

    Many factors affect the motion and transformation of oil at sea. The most relevant of these are the meteorological and marine conditions at the air-sea interface; the chemical characteristics of the oil; its initial volume and release rates; and, finally, the marine currents at different space scales and timescales. All these factors are interrelated and must be considered together to arrive at an accurate numerical representation of oil evolution and movement in seawater. The oil spill model code MEDSLIK-II is a freely available community model. By using a Lagrangian approach, MEDSLIK-II predicts the transport and diffusion of a surface oil slick governed by water currents, winds and waves, which are provided by operational oceanographic and meteorological models. In addition, the model simulates the oil transformations at sea: evaporation, spreading, dispersion, adhesion to coast and emulsification. The model results have been validated using surface drifters and oil slicks observed by satellite in different regions of the Mediterranean Sea. It is found that the forecast skill largely depends on the accuracy of the Eulerian ocean currents: the operational models give useful estimates of currents, but high-frequency (hourly) and high spatial resolution is required, and the Stokes drift velocity has to be often added, especially in coastal areas. MEDSLIK-II is today available at the Mediterranean scale allowing a possible support to oil spill emergencies. The model has been used during the Costa Concordia disaster, the partial sinking of the Italian cruise ship Costa Concordia when it ran aground at Isola del Giglio, Italy. MEDSLIK-II system was run to produce forecast scenarios of the possible oil spill from the Costa Concordia, to be delivered to the competent authorities, by using the currents provided every day by the operational ocean models available in the area. Moreover, MEDSLIK-II is part of the Mediterranean Decision Support System for Marine Safety

  15. Accurately Mapping M31's Microlensing Population

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin

    2004-07-01

    We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity

  16. Accurate upwind methods for the Euler equations

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1993-01-01

    A new class of piecewise linear methods for the numerical solution of the one-dimensional Euler equations of gas dynamics is presented. These methods are uniformly second-order accurate, and can be considered as extensions of Godunov's scheme. With an appropriate definition of monotonicity preservation for the case of linear convection, it can be shown that they preserve monotonicity. Similar to Van Leer's MUSCL scheme, they consist of two key steps: a reconstruction step followed by an upwind step. For the reconstruction step, a monotonicity constraint that preserves uniform second-order accuracy is introduced. Computational efficiency is enhanced by devising a criterion that detects the 'smooth' part of the data where the constraint is redundant. The concept and coding of the constraint are simplified by the use of the median function. A slope steepening technique, which has no effect at smooth regions and can resolve a contact discontinuity in four cells, is described. As for the upwind step, existing and new methods are applied in a manner slightly different from those in the literature. These methods are derived by approximating the Euler equations via linearization and diagonalization. At a 'smooth' interface, Harten, Lax, and Van Leer's one intermediate state model is employed. A modification for this model that can resolve contact discontinuities is presented. Near a discontinuity, either this modified model or a more accurate one, namely, Roe's flux-difference splitting. is used. The current presentation of Roe's method, via the conceptually simple flux-vector splitting, not only establishes a connection between the two splittings, but also leads to an admissibility correction with no conditional statement, and an efficient approximation to Osher's approximate Riemann solver. These reconstruction and upwind steps result in schemes that are uniformly second-order accurate and economical at smooth regions, and yield high resolution at discontinuities.

  17. Accurate measurement of unsteady state fluid temperature

    NASA Astrophysics Data System (ADS)

    Jaremkiewicz, Magdalena

    2016-07-01

    In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different construction but with the same housing outer diameter equal to 15 mm. One of them is a K-type industrial thermometer widely available commercially. The temperature indicated by the thermometer was corrected considering the thermometers as the first or second order inertia devices. The new design of a thermometer was proposed and also used to measure the temperature of boiling water. Its characteristic feature is a cylinder-shaped housing with the sheath thermocouple located in its center. The temperature of the fluid was determined based on measurements taken in the axis of the solid cylindrical element (housing) using the inverse space marching method. Measurements of the transient temperature of the air flowing through the wind tunnel using the same thermometers were also carried out. The proposed measurement technique provides more accurate results compared with measurements using industrial thermometers in conjunction with simple temperature correction using the inertial thermometer model of the first or second order. By comparing the results, it was demonstrated that the new thermometer allows obtaining the fluid temperature much faster and with higher accuracy in comparison to the industrial thermometer. Accurate measurements of the fast changing fluid temperature are possible due to the low inertia thermometer and fast space marching method applied for solving the inverse heat conduction problem.

  18. The first accurate description of an aurora

    NASA Astrophysics Data System (ADS)

    Schröder, Wilfried

    2006-12-01

    As technology has advanced, the scientific study of auroral phenomena has increased by leaps and bounds. A look back at the earliest descriptions of aurorae offers an interesting look into how medieval scholars viewed the subjects that we study.Although there are earlier fragmentary references in the literature, the first accurate description of the aurora borealis appears to be that published by the German Catholic scholar Konrad von Megenberg (1309-1374) in his book Das Buch der Natur (The Book of Nature). The book was written between 1349 and 1350.

  19. New law requires 'medically accurate' lesson plans.

    PubMed

    1999-09-17

    The California Legislature has passed a bill requiring all textbooks and materials used to teach about AIDS be medically accurate and objective. Statements made within the curriculum must be supported by research conducted in compliance with scientific methods, and published in peer-reviewed journals. Some of the current lesson plans were found to contain scientifically unsupported and biased information. In addition, the bill requires material to be "free of racial, ethnic, or gender biases." The legislation is supported by a wide range of interests, but opposed by the California Right to Life Education Fund, because they believe it discredits abstinence-only material.

  20. Accurate density functional thermochemistry for larger molecules.

    SciTech Connect

    Raghavachari, K.; Stefanov, B. B.; Curtiss, L. A.; Lucent Tech.

    1997-06-20

    Density functional methods are combined with isodesmic bond separation reaction energies to yield accurate thermochemistry for larger molecules. Seven different density functionals are assessed for the evaluation of heats of formation, Delta H 0 (298 K), for a test set of 40 molecules composed of H, C, O and N. The use of bond separation energies results in a dramatic improvement in the accuracy of all the density functionals. The B3-LYP functional has the smallest mean absolute deviation from experiment (1.5 kcal mol/f).

  1. New law requires 'medically accurate' lesson plans.

    PubMed

    1999-09-17

    The California Legislature has passed a bill requiring all textbooks and materials used to teach about AIDS be medically accurate and objective. Statements made within the curriculum must be supported by research conducted in compliance with scientific methods, and published in peer-reviewed journals. Some of the current lesson plans were found to contain scientifically unsupported and biased information. In addition, the bill requires material to be "free of racial, ethnic, or gender biases." The legislation is supported by a wide range of interests, but opposed by the California Right to Life Education Fund, because they believe it discredits abstinence-only material. PMID:11366835

  2. Universality: Accurate Checks in Dyson's Hierarchical Model

    NASA Astrophysics Data System (ADS)

    Godina, J. J.; Meurice, Y.; Oktay, M. B.

    2003-06-01

    In this talk we present high-accuracy calculations of the susceptibility near βc for Dyson's hierarchical model in D = 3. Using linear fitting, we estimate the leading (γ) and subleading (Δ) exponents. Independent estimates are obtained by calculating the first two eigenvalues of the linearized renormalization group transformation. We found γ = 1.29914073 ± 10 -8 and, Δ = 0.4259469 ± 10-7 independently of the choice of local integration measure (Ising or Landau-Ginzburg). After a suitable rescaling, the approximate fixed points for a large class of local measure coincide accurately with a fixed point constructed by Koch and Wittwer.

  3. Oil spills: Environmental effects. (Latest citations from the Selected Water Resources Abstracts database). Published Search

    SciTech Connect

    Not Available

    1993-01-01

    The bibliography contains citations concerning environmental impacts of oil spills primarily resulting from ship wrecks and oil drilling or exploration. Oil spills in temperate, tropic and arctic zones which affect fresh water, estuarine, and marine environments are included. Cleanup operations and priorities, computer modeling and simulation of oil spills, oil spill investigations, and prediction of oil slick movement in high traffic shipping lanes are among the topics discussed. Microbial degradation of oils, and toxicity studies of oils and oil dispersants affecting aquatic plant and animal life are considered. (Contains 250 citations and includes a subject term index and title list.)

  4. Oil spills: Environmental effects. (Latest citations from the Selected Water Resources Abstracts database). Published Search

    SciTech Connect

    Not Available

    1993-12-01

    The bibliography contains citations concerning environmental impacts of oil spills primarily resulting from ship wrecks and oil drilling or exploration. Oil spills in temperate, tropic and arctic zones which affect fresh water, estuarine, and marine environments are included. Cleanup operations and priorities, computer modeling and simulation of oil spills, oil spill investigations, and prediction of oil slick movement in high traffic shipping lanes are among the topics discussed. Microbial degradation of oils, and toxicity studies of oils and oil dispersants affecting aquatic plant and animal life are considered. (Contains 250 citations and includes a subject term index and title list.)

  5. Reservoir characterization and enhanced oil recovery research. Annual report, September 1988--August 1989

    SciTech Connect

    Lake, L.W.; Pope, G.A.; Schechter, R.S.

    1992-03-01

    The research in this annual report falls into three tasks each dealing with a different aspect of enhanced oil recovery. The first task strives to develop procedures for accurately modeling reservoirs for use as input to numerical simulation flow models. This action describes how we have used a detail characterization of an outcrop to provide insights into what features are important to fluid flow modeling. The second task deals with scaling-up and modeling chemical and solvent EOR processes. In a sense this task is the natural extension of task 1 and, in fact, one of the subtasks uses many of the same statistical procedures for insight into the effects of viscous fingering and heterogeneity. The final task involves surfactants and their interactions with carbon dioxide and reservoir minerals. This research deals primarily with phenomena observed when aqueous surfactant solutions are injected into oil reservoirs.

  6. Raman distributed temperature sensor for oil leakage detection in soil: a field trial and future trends

    NASA Astrophysics Data System (ADS)

    Signorini, Alessandro; Nannipieri, Tiziano; Gabella, Luca; Di Pasquale, Fabrizio; Latini, Gilberto; Ripari, Daniele

    2014-05-01

    In this paper we perform field validation of distributed Raman temperature sensing (RDTS) for oil leakage detection in soil. The capability of the distributed Raman sensor in detecting and locating, with high accuracy and spatial resolution, drop leakages in soil is demonstrated through a water leakage simulation in a field trial. The future trends and the high potential of the Raman DTS technology for oil and gas leakage detection in long pipelines is then outlined in this paper by reporting lab experiments demonstrating accurate meter scale temperature measurement over more than 50 km of standard single mode fiber. The proposed solution, based on distributed Simplex coding techniques, can be competitive in terms of cost and performance with respect to other distributed sensing technologies.

  7. MEDSLIK oil spill model recent developments

    NASA Astrophysics Data System (ADS)

    Lardner, Robin; Zodiatis, George

    2016-04-01

    MEDSLIK oil spill model recent developments Robin Lardner and George Zodiatis Oceanography Center, University of Cyprus, 1678 Nicosia, Cyprus MEDSLIK is a well established 3D oil spill model that predicts the transport, fate and weathering of oil spills and is used by several response agencies and institutions around the Mediterranean, the Black seas and worldwide. MEDSLIK has been used operationally for real oil spill accidents and for preparedness in contingency planning within the framework of pilot projects with REMPEC-Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea and EMSA-European Maritime Safety Agency. MEDSLIK has been implemented in many EU funded projects regarding oil spill predictions using the operational ocean forecasts, as for example the ECOOP, NEREIDs, RAOP-Med, EMODNET MedSea Check Point. Within the frame of MEDESS4MS project, MEDSLIK is at the heart of the MEDESS4MS multi model oil spill prediction system. The MEDSLIK oil spill model contains among other, the following features: a built-in database with 240 different oil types characteristics, assimilation of oil slick observations from in-situ or aerial, to correct the predictions, virtual deployment of oil booms and/or oil skimmers/dispersants, continuous or instantaneous oil spills from moving or drifting ships whose slicks merge can be modelled together, multiple oil spill predictions from different locations, backward simulations for tracking the source of oil spill pollution, integration with AIS data upon the availability of AIS data, sub-surface oil spills at any given water depth, coupling with SAR satellite data. The MEDSLIK can be used for operational intervention for any user-selected region in the world if the appropriate coastline, bathymetry and meteo-ocean forecast files are provided. MEDSLIK oil spill model has been extensively validated in the Mediterranean Sea, both in real oil spill incidents (i.e. during the Lebanese oil pollution crisis in

  8. Seismic Waves, 4th order accurate

    SciTech Connect

    2013-08-16

    SW4 is a program for simulating seismic wave propagation on parallel computers. SW4 colves the seismic wave equations in Cartesian corrdinates. It is therefore appropriate for regional simulations, where the curvature of the earth can be neglected. SW4 implements a free surface boundary condition on a realistic topography, absorbing super-grid conditions on the far-field boundaries, and a kinematic source model consisting of point force and/or point moment tensor source terms. SW4 supports a fully 3-D heterogeneous material model that can be specified in several formats. SW4 can output synthetic seismograms in an ASCII test format, or in the SAC finary format. It can also present simulation information as GMT scripts, whixh can be used to create annotated maps. Furthermore, SW4 can output the solution as well as the material model along 2-D grid planes.

  9. Seismic Waves, 4th order accurate

    2013-08-16

    SW4 is a program for simulating seismic wave propagation on parallel computers. SW4 colves the seismic wave equations in Cartesian corrdinates. It is therefore appropriate for regional simulations, where the curvature of the earth can be neglected. SW4 implements a free surface boundary condition on a realistic topography, absorbing super-grid conditions on the far-field boundaries, and a kinematic source model consisting of point force and/or point moment tensor source terms. SW4 supports a fully 3-Dmore » heterogeneous material model that can be specified in several formats. SW4 can output synthetic seismograms in an ASCII test format, or in the SAC finary format. It can also present simulation information as GMT scripts, whixh can be used to create annotated maps. Furthermore, SW4 can output the solution as well as the material model along 2-D grid planes.« less

  10. Application of HF radar currents to oil spill modelling.

    PubMed

    Abascal, Ana J; Castanedo, Sonia; Medina, Raul; Losada, Inigo J; Alvarez-Fanjul, Enrique

    2009-02-01

    In this work, the benefits of high-frequency (HF) radar currents for oil spill modeling and trajectory analysis of floating objects are analyzed. The HF radar performance is evaluated by means of comparison between a drifter buoy trajectory and the one simulated using a Lagrangian trajectory model. A methodology to optimize the transport model performance and to calculate the search area of the predicted positions is proposed. This method is applied to data collected during the Galicia HF Radar Experience. This experiment was carried out to explore the capabilities of this technology for operational monitoring along the Spanish coast. Two long-range HF radar stations were installed and operated between November 2005 and February 2006 on the Galician coast. In addition, a drifter buoy was released inside the coverage area of the radar. The HF radar currents, as well as numerical wind data were used to simulate the buoy trajectory using the TESEO oil spill transport model. In order to evaluate the contribution of HF radar currents to trajectory analysis, two simulation alternatives were carried out. In the first one, wind data were used to simulate the motion of the buoy. In the second alternative, surface currents from the HF radar were also taken into account. For each alternative, the model was calibrated by means of the global optimization algorithm SCEM-UA (Shuffled Complex Evolution Metropolis) in order to obtain the probability density function of the model parameters. The buoy trajectory was computed for 24h intervals using a Monte Carlo approach based on the results provided in the calibration process. A bivariate kernel estimator was applied to determine the 95% confidence areas. The analysis performed showed that simulated trajectories integrating HF radar currents are more accurate than those obtained considering only wind numerical data. After a 24h period, the error in the final simulated position improves using HF radar currents. Averaging the

  11. Cleaning oiled shores: laboratory experiments testing the potential use of vegetable oil biodiesels.

    PubMed

    Pereira, M Glória; Mudge, Stephen M

    2004-01-01

    A series of laboratory experiments were carried out to test the potential of vegetable oil biodiesel for the cleaning of oiled shorelines. In batch experiments, biodiesel was shown to have a considerable capacity to dissolve crude oil, which appears to be dependent on the type of biodiesel used. Pure vegetable oil biodiesels (rapeseed and soybean) were significantly more effective in the cleanup of oiled sands (up to 96%) than recycled waste cooking oil biodiesel (70%). In microcosm and mesocosm experiments, oiled sediments were sprayed with biodiesel and subjected to simulated tides. Microcosm experiments revealed that, of those tested, the highest ratio of biodiesel to crude oil, had the highest effectiveness for cleaning fine sands, with ratios of 2:1 (biodiesel:crude oil) giving the best results. In the mesocosm experiments a ratio 1:1 of soybean biodiesel to crude oil removed 80% of the oil in cobbles and fine sands, 50% in coarse sand and 30% in gravel. Most of the oil was removed with the surface water, with only a small amount being flushed through the sediments. Particle size and pore size were important determinants in the cleanup and mobility of crude oil in the sediments in these static systems. It is expected that the biodiesel effectiveness should improve in the natural environment particularly in exposed beaches with strong wave action. However, more laboratory and field trials are required to confirm the operational use of biodiesel as a shoreline cleaner.

  12. Cleaning oiled shores: laboratory experiments testing the potential use of vegetable oil biodiesels.

    PubMed

    Pereira, M Glória; Mudge, Stephen M

    2004-01-01

    A series of laboratory experiments were carried out to test the potential of vegetable oil biodiesel for the cleaning of oiled shorelines. In batch experiments, biodiesel was shown to have a considerable capacity to dissolve crude oil, which appears to be dependent on the type of biodiesel used. Pure vegetable oil biodiesels (rapeseed and soybean) were significantly more effective in the cleanup of oiled sands (up to 96%) than recycled waste cooking oil biodiesel (70%). In microcosm and mesocosm experiments, oiled sediments were sprayed with biodiesel and subjected to simulated tides. Microcosm experiments revealed that, of those tested, the highest ratio of biodiesel to crude oil, had the highest effectiveness for cleaning fine sands, with ratios of 2:1 (biodiesel:crude oil) giving the best results. In the mesocosm experiments a ratio 1:1 of soybean biodiesel to crude oil removed 80% of the oil in cobbles and fine sands, 50% in coarse sand and 30% in gravel. Most of the oil was removed with the surface water, with only a small amount being flushed through the sediments. Particle size and pore size were important determinants in the cleanup and mobility of crude oil in the sediments in these static systems. It is expected that the biodiesel effectiveness should improve in the natural environment particularly in exposed beaches with strong wave action. However, more laboratory and field trials are required to confirm the operational use of biodiesel as a shoreline cleaner. PMID:14575742

  13. Design of the KOSMOS oil-coupled spectrograph camera lenses

    NASA Astrophysics Data System (ADS)

    O'Brien, Thomas P.; Derwent, Mark; Martini, Paul; Poczulp, Gary

    2014-07-01

    We present the design details of oil-coupled lens groups used in the KOSMOS spectrograph camera. The oil-coupled groups use silicone rubber O-rings in a unique way to accurately center lens elements with high radial and axial stiffness while also allowing easy assembly. The O-rings robustly seal the oil within the lens gaps to prevent oil migration. The design of an expansion diaphragm to compensate for differential expansion due to temperature changes is described. The issues of lens assembly, lens gap shimming, oil filling and draining, bubble mitigation, material compatibility, mechanical inspection, and optical testing are discussed.

  14. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  15. Accurate basis set truncation for wavefunction embedding

    NASA Astrophysics Data System (ADS)

    Barnes, Taylor A.; Goodpaster, Jason D.; Manby, Frederick R.; Miller, Thomas F.

    2013-07-01

    Density functional theory (DFT) provides a formally exact framework for performing embedded subsystem electronic structure calculations, including DFT-in-DFT and wavefunction theory-in-DFT descriptions. In the interest of efficiency, it is desirable to truncate the atomic orbital basis set in which the subsystem calculation is performed, thus avoiding high-order scaling with respect to the size of the MO virtual space. In this study, we extend a recently introduced projection-based embedding method [F. R. Manby, M. Stella, J. D. Goodpaster, and T. F. Miller III, J. Chem. Theory Comput. 8, 2564 (2012)], 10.1021/ct300544e to allow for the systematic and accurate truncation of the embedded subsystem basis set. The approach is applied to both covalently and non-covalently bound test cases, including water clusters and polypeptide chains, and it is demonstrated that errors associated with basis set truncation are controllable to well within chemical accuracy. Furthermore, we show that this approach allows for switching between accurate projection-based embedding and DFT embedding with approximate kinetic energy (KE) functionals; in this sense, the approach provides a means of systematically improving upon the use of approximate KE functionals in DFT embedding.

  16. How Accurately can we Calculate Thermal Systems?

    SciTech Connect

    Cullen, D; Blomquist, R N; Dean, C; Heinrichs, D; Kalugin, M A; Lee, M; Lee, Y; MacFarlan, R; Nagaya, Y; Trkov, A

    2004-04-20

    I would like to determine how accurately a variety of neutron transport code packages (code and cross section libraries) can calculate simple integral parameters, such as K{sub eff}, for systems that are sensitive to thermal neutron scattering. Since we will only consider theoretical systems, we cannot really determine absolute accuracy compared to any real system. Therefore rather than accuracy, it would be more precise to say that I would like to determine the spread in answers that we obtain from a variety of code packages. This spread should serve as an excellent indicator of how accurately we can really model and calculate such systems today. Hopefully, eventually this will lead to improvements in both our codes and the thermal scattering models that they use in the future. In order to accomplish this I propose a number of extremely simple systems that involve thermal neutron scattering that can be easily modeled and calculated by a variety of neutron transport codes. These are theoretical systems designed to emphasize the effects of thermal scattering, since that is what we are interested in studying. I have attempted to keep these systems very simple, and yet at the same time they include most, if not all, of the important thermal scattering effects encountered in a large, water-moderated, uranium fueled thermal system, i.e., our typical thermal reactors.

  17. Accurate Stellar Parameters for Exoplanet Host Stars

    NASA Astrophysics Data System (ADS)

    Brewer, John Michael; Fischer, Debra; Basu, Sarbani; Valenti, Jeff A.

    2015-01-01

    A large impedement to our understanding of planet formation is obtaining a clear picture of planet radii and densities. Although determining precise ratios between planet and stellar host are relatively easy, determining accurate stellar parameters is still a difficult and costly undertaking. High resolution spectral analysis has traditionally yielded precise values for some stellar parameters but stars in common between catalogs from different authors or analyzed using different techniques often show offsets far in excess of their uncertainties. Most analyses now use some external constraint, when available, to break observed degeneracies between surface gravity, effective temperature, and metallicity which can otherwise lead to correlated errors in results. However, these external constraints are impossible to obtain for all stars and can require more costly observations than the initial high resolution spectra. We demonstrate that these discrepencies can be mitigated by use of a larger line list that has carefully tuned atomic line data. We use an iterative modeling technique that does not require external constraints. We compare the surface gravity obtained with our spectral synthesis modeling to asteroseismically determined values for 42 Kepler stars. Our analysis agrees well with only a 0.048 dex offset and an rms scatter of 0.05 dex. Such accurate stellar gravities can reduce the primary source of uncertainty in radii by almost an order of magnitude over unconstrained spectral analysis.

  18. Simulation of the hydrogeologic effects of oil-shale mining on the neighbouring wetland water balance: case study in north-eastern Estonia

    NASA Astrophysics Data System (ADS)

    Marandi, Andres; Karro, Enn; Polikarpus, Maile; Jõeleht, Argo; Kohv, Marko; Hang, Tiit; Hiiemaa, Helen

    2013-11-01

    The water balance of wetlands plays an integral role in their function. Developments adjacent to wetlands can affect their water balance through impacts on groundwater flow and increased discharge in the area, and they can cause lowering of the wetland water table. A 430 km2 area was selected for groundwater modelling to asses the effect of underground mining on the water balance of wetlands in north-eastern Estonia. A nature conservation area (encompassing Selisoo bog) is within 3 km of an underground oil-shale mine. Two future mining scenarios with different areal extents of mining were modeled and compared to the present situation. Results show that the vertical hydraulic conductivity of the subsurface is of critical importance to potential wetland dewatering as a result of mining. Significant impact on the Selisoo bog water balance will be caused by the approaching mine but there will be only minor additional impacts from mining directly below the bog. The major impact will arise before that stage, when the underground mine extension reaches the border of the nature conservation area; since the restriction of activities in this area relates to the ground surface, the conservation area’s border is not sufficiently protective in relation to underground development.

  19. Integrating mixed-effect models into an architectural plant model to simulate inter- and intra-progeny variability: a case study on oil palm (Elaeis guineensis Jacq.).

    PubMed

    Perez, Raphaël P A; Pallas, Benoît; Le Moguédec, Gilles; Rey, Hervé; Griffon, Sébastien; Caliman, Jean-Pierre; Costes, Evelyne; Dauzat, Jean

    2016-08-01

    Three-dimensional (3D) reconstruction of plants is time-consuming and involves considerable levels of data acquisition. This is possibly one reason why the integration of genetic variability into 3D architectural models has so far been largely overlooked. In this study, an allometry-based approach was developed to account for architectural variability in 3D architectural models of oil palm (Elaeis guineensis Jacq.) as a case study. Allometric relationships were used to model architectural traits from individual leaflets to the entire crown while accounting for ontogenetic and morphogenetic gradients. Inter- and intra-progeny variabilities were evaluated for each trait and mixed-effect models were used to estimate the mean and variance parameters required for complete 3D virtual plants. Significant differences in leaf geometry (petiole length, density of leaflets, and rachis curvature) and leaflet morphology (gradients of leaflet length and width) were detected between and within progenies and were modelled in order to generate populations of plants that were consistent with the observed populations. The application of mixed-effect models on allometric relationships highlighted an interesting trade-off between model accuracy and ease of defining parameters for the 3D reconstruction of plants while at the same time integrating their observed variability. Future research will be dedicated to sensitivity analyses coupling the structural model presented here with a radiative balance model in order to identify the key architectural traits involved in light interception efficiency. PMID:27302128

  20. Integrating mixed-effect models into an architectural plant model to simulate inter- and intra-progeny variability: a case study on oil palm (Elaeis guineensis Jacq.).

    PubMed

    Perez, Raphaël P A; Pallas, Benoît; Le Moguédec, Gilles; Rey, Hervé; Griffon, Sébastien; Caliman, Jean-Pierre; Costes, Evelyne; Dauzat, Jean

    2016-08-01

    Three-dimensional (3D) reconstruction of plants is time-consuming and involves considerable levels of data acquisition. This is possibly one reason why the integration of genetic variability into 3D architectural models has so far been largely overlooked. In this study, an allometry-based approach was developed to account for architectural variability in 3D architectural models of oil palm (Elaeis guineensis Jacq.) as a case study. Allometric relationships were used to model architectural traits from individual leaflets to the entire crown while accounting for ontogenetic and morphogenetic gradients. Inter- and intra-progeny variabilities were evaluated for each trait and mixed-effect models were used to estimate the mean and variance parameters required for complete 3D virtual plants. Significant differences in leaf geometry (petiole length, density of leaflets, and rachis curvature) and leaflet morphology (gradients of leaflet length and width) were detected between and within progenies and were modelled in order to generate populations of plants that were consistent with the observed populations. The application of mixed-effect models on allometric relationships highlighted an interesting trade-off between model accuracy and ease of defining parameters for the 3D reconstruction of plants while at the same time integrating their observed variability. Future research will be dedicated to sensitivity analyses coupling the structural model presented here with a radiative balance model in order to identify the key architectural traits involved in light interception efficiency.