Note: A table-top blast driven shock tube

NASA Astrophysics Data System (ADS)

Courtney, Michael W.; Courtney, Amy C.

2010-12-01

The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

Note: A table-top blast driven shock tube.

PubMed

Courtney, Michael W; Courtney, Amy C

2010-12-01

The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

Chip-Scale Trace-Gas Spectrometers for Methane Leak Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, William

Panelists from industry, academia, government laboratories and venture capital community will discuss opportunities driven by miniaturization of spectroscopic sensing systems and optical sensor applications. The speakers will discuss industry needs for wide-range commercial, security and defense applications. Listen and interact with leaders in the spectroscopy and sensing community, and come to share your ideas.

Scientific rigor through videogames.

PubMed

Treuille, Adrien; Das, Rhiju

2014-11-01

Hypothesis-driven experimentation - the scientific method - can be subverted by fraud, irreproducibility, and lack of rigorous predictive tests. A robust solution to these problems may be the 'massive open laboratory' model, recently embodied in the internet-scale videogame EteRNA. Deploying similar platforms throughout biology could enforce the scientific method more broadly. Copyright © 2014 Elsevier Ltd. All rights reserved.

Toward laboratory torsional spine magnetic reconnection

NASA Astrophysics Data System (ADS)

Chesny, David L.; Orange, N. Brice; Oluseyi, Hakeem M.; Valletta, David R.

2017-12-01

Magnetic reconnection is a fundamental energy conversion mechanism in nature. Major attempts to study this process in controlled settings on Earth have largely been limited to reproducing approximately two-dimensional (2-D) reconnection dynamics. Other experiments describing reconnection near three-dimensional null points are non-driven, and do not induce any of the 3-D modes of spine fan, torsional fan or torsional spine reconnection. In order to study these important 3-D modes observed in astrophysical plasmas (e.g. the solar atmosphere), laboratory set-ups must be designed to induce driven reconnection about an isolated magnetic null point. As such, we consider the limited range of fundamental resistive magnetohydrodynamic (MHD) and kinetic parameters of dynamic laboratory plasmas that are necessary to induce the torsional spine reconnection (TSR) mode characterized by a driven rotational slippage of field lines - a feature that has yet to be achieved in operational laboratory magnetic reconnection experiments. Leveraging existing reconnection models, we show that within a 3$ apparatus, TSR can be achieved in dense plasma regimes ( 24~\\text{m}-3$ ) in magnetic fields of -1~\\text{T}$ . We find that MHD and kinetic parameters predict reconnection in thin current sheets on time scales of . While these plasma regimes may not explicitly replicate the plasma parameters of observed astrophysical phenomena, studying the dynamics of the TSR mode within achievable set-ups signifies an important step in understanding the fundamentals of driven 3-D magnetic reconnection and the self-organization of current sheets. Explicit control of this reconnection mode may have implications for understanding particle acceleration in astrophysical environments, and may even have practical applications to fields such as spacecraft propulsion.

The value of the Semantic Web in the laboratory.

PubMed

Frey, Jeremy G

2009-06-01

The Semantic Web is beginning to impact on the wider chemical and physical sciences, beyond the earlier adopted bio-informatics. While useful in large-scale data driven science with automated processing, these technologies can also help integrate the work of smaller scale laboratories producing diverse data. The semantics aid the discovery, reliable re-use of data, provide improved provenance and facilitate automated processing by increased resilience to changes in presentation and reduced ambiguity. The Semantic Web, its tools and collections are not yet competitive with well-established solutions to current problems. It is in the reduced cost of instituting solutions to new problems that the versatility of Semantic Web-enabled data and resources will make their mark once the more general-purpose tools are more available.

Laboratory observation of resistive electron tearing in a two-fluid reconnecting current sheet

DOE PAGES

Jara-Almonte, Jonathan; Ji, Hantao; Yamada, Masaaki; ...

2016-08-25

The spontaneous formation of plasmoids via the resistive electron tearing of a reconnecting current sheet is observed in the laboratory. These experiments are performed during driven, antiparallel reconnection in the two-fluid regime within the Magnetic Reconnection Experiment. It is found that plasmoids are present even at a very low Lundquist number, and the number of plasmoids scales with both the current sheet aspect ratio and the Lundquist number. Furthermore, the reconnection electric field increases when plasmoids are formed, leading to an enhanced reconnection rate.

Dehydration-driven stress transfer triggers intermediate-depth earthquakes

NASA Astrophysics Data System (ADS)

Ferrand, Thomas P.; Hilairet, Nadège; Incel, Sarah; Deldicque, Damien; Labrousse, Loïc; Gasc, Julien; Renner, Joerg; Wang, Yanbin; Green, Harry W., II; Schubnel, Alexandre

2017-05-01

Intermediate-depth earthquakes (30-300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here we decipher the mechanism of these earthquakes by performing deformation experiments on dehydrating serpentinized peridotites (synthetic antigorite-olivine aggregates, minerals representative of subduction zones lithologies) at upper mantle conditions. At a pressure of 1.1 gigapascals, dehydration of deforming samples containing only 5 vol% of antigorite suffices to trigger acoustic emissions, a laboratory-scale analogue of earthquakes. At 3.5 gigapascals, acoustic emissions are recorded from samples with up to 50 vol% of antigorite. Experimentally produced faults, observed post-mortem, are sealed by fluid-bearing micro-pseudotachylytes. Microstructural observations demonstrate that antigorite dehydration triggered dynamic shear failure of the olivine load-bearing network. These laboratory analogues of intermediate-depth earthquakes demonstrate that little dehydration is required to trigger embrittlement. We propose an alternative model to dehydration-embrittlement in which dehydration-driven stress transfer, rather than fluid overpressure, causes embrittlement.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendelsohn, M.; Kreycik, C.

Utility-scale solar projects have grown rapidly in number and size over the last few years, driven in part by strong renewable portfolio standards (RPS) and federal incentives designed to stimulate investment in renewable energy technologies. This report provides an overview of such policies, as well as the project financial structures they enable, based on industry literature, publicly available data, and questionnaires conducted by the National Renewable Energy Laboratory (NREL).

Experiments and simulations of flux rope dynamics in a plasma

NASA Astrophysics Data System (ADS)

Intrator, Thomas; Abbate, Sara; Ryutov, Dmitri

2005-10-01

The behavior of flux ropes is a key issue in solar, space and astrophysics. For instance, magnetic fields and currents on the Sun are sheared and twisted as they store energy, experience an as yet unidentified instability, open into interplanetary space, eject the plasma trapped in them, and cause a flare. The Reconnection Scaling Experiment (RSX) provides a simple means to systematically characterize the linear and non-linear evolution of driven, dissipative, unstable plasma-current filaments. Topology evolves in three dimensions, supports multiple modes, and can bifurcate to quasi-helical equilibria. The ultimate saturation to a nonlinear force and energy balance is the link to a spectrum of relaxation processes. RSX has adjustable energy density β1 to β 1, non-negligible equilibrium plasma flows, driven steady-state scenarios, and adjustable line tying at boundaries. We will show magnetic structure of a kinking, rotating single line tied column, magnetic reconnection between two flux ropes, and pictures of three braided flux ropes. We use computed simulation movies to bridge the gap between the solar physics scales and experimental data with computational modeling. In collaboration with Ivo Furno, Tsitsi Madziwa-Nussinovm Giovanni Lapenta, Adam Light, Los Alamos National Laboratory; Sara Abbate, Torino Polytecnico; and Dmitri Ryutov, Lawrence Livermore National Laboratory.

Demonstrating the feasibility of large-scale development of standardized assays to quantify human proteins

PubMed Central

Kennedy, Jacob J.; Abbatiello, Susan E.; Kim, Kyunggon; Yan, Ping; Whiteaker, Jeffrey R.; Lin, Chenwei; Kim, Jun Seok; Zhang, Yuzheng; Wang, Xianlong; Ivey, Richard G.; Zhao, Lei; Min, Hophil; Lee, Youngju; Yu, Myeong-Hee; Yang, Eun Gyeong; Lee, Cheolju; Wang, Pei; Rodriguez, Henry; Kim, Youngsoo; Carr, Steven A.; Paulovich, Amanda G.

2014-01-01

The successful application of MRM in biological specimens raises the exciting possibility that assays can be configured to measure all human proteins, resulting in an assay resource that would promote advances in biomedical research. We report the results of a pilot study designed to test the feasibility of a large-scale, international effort in MRM assay generation. We have configured, validated across three laboratories, and made publicly available as a resource to the community 645 novel MRM assays representing 319 proteins expressed in human breast cancer. Assays were multiplexed in groups of >150 peptides and deployed to quantify endogenous analyte in a panel of breast cancer-related cell lines. Median assay precision was 5.4%, with high inter-laboratory correlation (R2 >0.96). Peptide measurements in breast cancer cell lines were able to discriminate amongst molecular subtypes and identify genome-driven changes in the cancer proteome. These results establish the feasibility of a scaled, international effort. PMID:24317253

Dehydration-driven stress transfer triggers intermediate-depth earthquakes

PubMed Central

Ferrand, Thomas P.; Hilairet, Nadège; Incel, Sarah; Deldicque, Damien; Labrousse, Loïc; Gasc, Julien; Renner, Joerg; Wang, Yanbin; Green II, Harry W.; Schubnel, Alexandre

2017-01-01

Intermediate-depth earthquakes (30–300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here we decipher the mechanism of these earthquakes by performing deformation experiments on dehydrating serpentinized peridotites (synthetic antigorite-olivine aggregates, minerals representative of subduction zones lithologies) at upper mantle conditions. At a pressure of 1.1 gigapascals, dehydration of deforming samples containing only 5 vol% of antigorite suffices to trigger acoustic emissions, a laboratory-scale analogue of earthquakes. At 3.5 gigapascals, acoustic emissions are recorded from samples with up to 50 vol% of antigorite. Experimentally produced faults, observed post-mortem, are sealed by fluid-bearing micro-pseudotachylytes. Microstructural observations demonstrate that antigorite dehydration triggered dynamic shear failure of the olivine load-bearing network. These laboratory analogues of intermediate-depth earthquakes demonstrate that little dehydration is required to trigger embrittlement. We propose an alternative model to dehydration-embrittlement in which dehydration-driven stress transfer, rather than fluid overpressure, causes embrittlement. PMID:28504263

Dehydration-driven stress transfer triggers intermediate-depth earthquakes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrand, Thomas P.; Hilairet, Nadège; Incel, Sarah

Intermediate-depth earthquakes (30–300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here in this paper we decipher the mechanism of these earthquakes by performing deformation experiments on dehydrating serpentinized peridotites (synthetic antigorite-olivine aggregates, minerals representative of subduction zones lithologies) at upper mantle conditions. At a pressure of 1.1 gigapascals, dehydration of deforming samples containing only 5 vol% of antigorite suffices to trigger acoustic emissions, a laboratory-scale analogue of earthquakes. At 3.5 gigapascals, acoustic emissions are recorded from samples with up to 50 vol% of antigorite. Experimentally produced faults, observed post-mortem, are sealed by fluid-bearingmore » micro-pseudotachylytes. Microstructural observations demonstrate that antigorite dehydration triggered dynamic shear failure of the olivine load-bearing network. These laboratory analogues of intermediatedepth earthquakes demonstrate that little dehydration is required to trigger embrittlement. We propose an alternative model to dehydration-embrittlement in which dehydration-driven stress transfer, rather than fluid overpressure, causes embrittlement.« less

Dehydration-driven stress transfer triggers intermediate-depth earthquakes

DOE PAGES

Ferrand, Thomas P.; Hilairet, Nadège; Incel, Sarah; ...

2017-05-15

Intermediate-depth earthquakes (30–300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here in this paper we decipher the mechanism of these earthquakes by performing deformation experiments on dehydrating serpentinized peridotites (synthetic antigorite-olivine aggregates, minerals representative of subduction zones lithologies) at upper mantle conditions. At a pressure of 1.1 gigapascals, dehydration of deforming samples containing only 5 vol% of antigorite suffices to trigger acoustic emissions, a laboratory-scale analogue of earthquakes. At 3.5 gigapascals, acoustic emissions are recorded from samples with up to 50 vol% of antigorite. Experimentally produced faults, observed post-mortem, are sealed by fluid-bearingmore » micro-pseudotachylytes. Microstructural observations demonstrate that antigorite dehydration triggered dynamic shear failure of the olivine load-bearing network. These laboratory analogues of intermediatedepth earthquakes demonstrate that little dehydration is required to trigger embrittlement. We propose an alternative model to dehydration-embrittlement in which dehydration-driven stress transfer, rather than fluid overpressure, causes embrittlement.« less

Guiding of relativistic electron beams in dense matter by laser-driven magnetostatic fields.

PubMed

Bailly-Grandvaux, M; Santos, J J; Bellei, C; Forestier-Colleoni, P; Fujioka, S; Giuffrida, L; Honrubia, J J; Batani, D; Bouillaud, R; Chevrot, M; Cross, J E; Crowston, R; Dorard, S; Dubois, J-L; Ehret, M; Gregori, G; Hulin, S; Kojima, S; Loyez, E; Marquès, J-R; Morace, A; Nicolaï, Ph; Roth, M; Sakata, S; Schaumann, G; Serres, F; Servel, J; Tikhonchuk, V T; Woolsey, N; Zhang, Z

2018-01-09

Intense lasers interacting with dense targets accelerate relativistic electron beams, which transport part of the laser energy into the target depth. However, the overall laser-to-target energy coupling efficiency is impaired by the large divergence of the electron beam, intrinsic to the laser-plasma interaction. Here we demonstrate that an efficient guiding of MeV electrons with about 30 MA current in solid matter is obtained by imposing a laser-driven longitudinal magnetostatic field of 600 T. In the magnetized conditions the transported energy density and the peak background electron temperature at the 60-μm-thick target's rear surface rise by about a factor of five, as unfolded from benchmarked simulations. Such an improvement of energy-density flux through dense matter paves the ground for advances in laser-driven intense sources of energetic particles and radiation, driving matter to extreme temperatures, reaching states relevant for planetary or stellar science as yet inaccessible at the laboratory scale and achieving high-gain laser-driven thermonuclear fusion.

Above scaling short-pulse ion acceleration from flat foil and ``Pizza-top Cone'' targets at the Trident laser facility

NASA Astrophysics Data System (ADS)

Flippo, Kirk; Hegelich, B. Manuel; Cort Gautier, D.; Johnson, J. Randy; Kline, John L.; Shimada, Tsutomu; Fernández, Juan C.; Gaillard, Sandrine; Rassuchine, Jennifer; Le Galloudec, Nathalie; Cowan, Thomas E.; Malekos, Steve; Korgan, Grant

2006-10-01

Ion-driven Fast Ignition (IFI) has certain advantages over electron-driven FI due to a possible large reduction in the amount of energy required. Recent experiments at the Los Alamos National Laboratory's Trident facility have yielded ion energies and efficiencies many times in excess of recent published scaling laws, leading to even more potential advantages of IFI. Proton energies in excess of 35 MeV have been observed from targets produced by the University of Nevada, Reno - dubbed ``Pizza-top Cone'' targets - at intensities of only 1x10^19 W/cm^2 with 20 joules in 600 fs. Energies in excess of 24 MeV were observed from simple flat foil targets as well. The observed energies, above any published scaling laws, are attributed to target production, preparation, and shot to shot monitoring of many laser parameters, especially the laser ASE prepulse level and laser pulse duration. The laser parameters are monitored in real-time to keep the laser in optimal condition throughout the run providing high quality, reproducible shots.

A review of analogue modelling of geodynamic processes: Approaches, scaling, materials and quantification, with an application to subduction experiments

NASA Astrophysics Data System (ADS)

Schellart, Wouter P.; Strak, Vincent

2016-10-01

We present a review of the analogue modelling method, which has been used for 200 years, and continues to be used, to investigate geological phenomena and geodynamic processes. We particularly focus on the following four components: (1) the different fundamental modelling approaches that exist in analogue modelling; (2) the scaling theory and scaling of topography; (3) the different materials and rheologies that are used to simulate the complex behaviour of rocks; and (4) a range of recording techniques that are used for qualitative and quantitative analyses and interpretations of analogue models. Furthermore, we apply these four components to laboratory-based subduction models and describe some of the issues at hand with modelling such systems. Over the last 200 years, a wide variety of analogue materials have been used with different rheologies, including viscous materials (e.g. syrups, silicones, water), brittle materials (e.g. granular materials such as sand, microspheres and sugar), plastic materials (e.g. plasticine), visco-plastic materials (e.g. paraffin, waxes, petrolatum) and visco-elasto-plastic materials (e.g. hydrocarbon compounds and gelatins). These materials have been used in many different set-ups to study processes from the microscale, such as porphyroclast rotation, to the mantle scale, such as subduction and mantle convection. Despite the wide variety of modelling materials and great diversity in model set-ups and processes investigated, all laboratory experiments can be classified into one of three different categories based on three fundamental modelling approaches that have been used in analogue modelling: (1) The external approach, (2) the combined (external + internal) approach, and (3) the internal approach. In the external approach and combined approach, energy is added to the experimental system through the external application of a velocity, temperature gradient or a material influx (or a combination thereof), and so the system is open. In the external approach, all deformation in the system is driven by the externally imposed condition, while in the combined approach, part of the deformation is driven by buoyancy forces internal to the system. In the internal approach, all deformation is driven by buoyancy forces internal to the system and so the system is closed and no energy is added during an experimental run. In the combined approach, the externally imposed force or added energy is generally not quantified nor compared to the internal buoyancy force or potential energy of the system, and so it is not known if these experiments are properly scaled with respect to nature. The scaling theory requires that analogue models are geometrically, kinematically and dynamically similar to the natural prototype. Direct scaling of topography in laboratory models indicates that it is often significantly exaggerated. This can be ascribed to (1) The lack of isostatic compensation, which causes topography to be too high. (2) The lack of erosion, which causes topography to be too high. (3) The incorrect scaling of topography when density contrasts are scaled (rather than densities); In isostatically supported models, scaling of density contrasts requires an adjustment of the scaled topography by applying a topographic correction factor. (4) The incorrect scaling of externally imposed boundary conditions in isostatically supported experiments using the combined approach; When externally imposed forces are too high, this creates topography that is too high. Other processes that also affect surface topography in laboratory models but not in nature (or only in a negligible way) include surface tension (for models using fluids) and shear zone dilatation (for models using granular material), but these will generally only affect the model surface topography on relatively short horizontal length scales of the order of several mm across material boundaries and shear zones, respectively.

Laboratory flow experiments for visualizing carbon dioxide-induced, density-driven brine convection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kneafsey, T.; Pruess, K.

2009-09-01

Injection of carbon dioxide (CO{sub 2}) into saline aquifers confined by low-permeability cap rock will result in a layer of CO{sub 2} overlying the brine. Dissolution of CO{sub 2} into the brine increases the brine density, resulting in an unstable situation in which more-dense brine overlies less-dense brine. This gravitational instability could give rise to density-driven convection of the fluid, which is a favorable process of practical interest for CO{sub 2} storage security because it accelerates the transfer of buoyant CO{sub 2} into the aqueous phase, where it is no longer subject to an upward buoyant drive. Laboratory flow visualizationmore » tests in transparent Hele-Shaw cells have been performed to elucidate the processes and rates of this CO{sub 2} solute-driven convection (CSC). Upon introduction of CO{sub 2} into the system, a layer of CO{sub 2}-laden brine forms at the CO{sub 2}-water interface. Subsequently, small convective fingers form, which coalesce, broaden, and penetrate into the test cell. Images and time-series data of finger lengths and wavelengths are presented. Observed CO{sub 2} uptake of the convection system indicates that the CO{sub 2} dissolution rate is approximately constant for each test and is far greater than expected for a diffusion-only scenario. Numerical simulations of our system show good agreement with the experiments for onset time of convection and advancement of convective fingers. There are differences as well, the most prominent being the absence of cell-scale convection in the numerical simulations. This cell-scale convection observed in the experiments is probably initiated by a small temperature gradient induced by the cell illumination.« less

An Experimental Study of Penny-shaped Fluid-driven Cracks in an Elastic Matrix

NASA Astrophysics Data System (ADS)

Stone, Howard

2015-11-01

When a pressurized fluid is injected into an elastic matrix, the fluid generates a fracture that grows along a plane and forms a fluid-filled disc-like shape. For example, such problems occur in various natural and industrial applications involving the subsurface of Earth, such as hydraulic fracturing operations. We report a laboratory study of such a fluid-driven crack in a gelatin matrix, study the crack shape as a function of time, and investigate the influence of different experimental parameters such as the injection flow rate, Young's modulus of the matrix, and fluid viscosity. We find that the crack radius increases with time as a power law, which has been predicted both for the limit where viscous effects in the flow along the crack opening control the rate of crack propagation, as well as the limit where fracture toughness controls crack propagation. We vary experimental parameters to probe the physical limits and highlight that for our typical parameters both effects can be significant. Also, we measure the time evolution of crack shape, which has not been studied before. The rescaled crack shapes collapse at longer times, based on an appropriate scaling argument, and again we compare the scaling arguments in different physical limits. The gelatin system provides a useful laboratory model for further studies of fluid-driven cracks, some of which we will mention as they are inspired by the physics of hydraulic fracturing. This work is part of the PhD thesis of Ching-Yao Lai and is a collaboration with Drs. Zhong Zheng and Jason Wexler (Princeton University) and Professor Emilie Dressaire (NYU). Department of Mechanical and Aerospace Engineering.

Experiments on Thermal Convection in Rotating Spherical Shells With Radial Gravity: The Geophysical Fluid Flow Cell

NASA Technical Reports Server (NTRS)

Hart, John E.

1996-01-01

Experiments designed to study the fluid dynamics of buoyancy driven circulations in rotating spherical shells were conducted on the United States Microgravity Laboratory 2 spacelab mission. These experiments address several aspects of prototypical global convection relevant to large scale motions on the Sun, Earth, and on the giant planets. The key feature is the consistent modeling of radially directed gravity in spherical geometry by using dielectric polarization forces. Imagery of the planforms of thermally driven flows for rapidly-rotating regimes shows an initial separation and eventual merger of equatorial and polar convection as the heating (i.e. the Rayleigh number) is increased. At low rotation rates, multiple-states of motion for the same external parameters were observed.

Partitioning dynamics of unsaturated flows in fractured porous media: Laboratory studies and three-dimensional multi-scale smoothed particle hydrodynamics simulations of gravity-driven flow in fractures

NASA Astrophysics Data System (ADS)

Kordilla, J.; Bresinsky, L. T.; Shigorina, E.; Noffz, T.; Dentz, M.; Sauter, M.; Tartakovsky, A. M.

2017-12-01

Preferential flow dynamics in unsaturated fractures remain a challenging topic on various scales. On pore- and fracture-scales the highly erratic gravity-driven flow dynamics often provoke a strong deviation from classical volume-effective approaches. Against the common notion that flow in fractures (or macropores) can only occur under equilibrium conditions, i.e., if the surrounding porous matrix is fully saturated and capillary pressures are high enough to allow filling of the fracture void space, arrival times suggest the existence of rapid preferential flow along fractures, fracture networks, and fault zones, even if the matrix is not fully saturated. Modeling such flows requires efficient numerical techniques to cover various flow-relevant physics, such as surface tension, static and dynamic contact angles, free-surface (multi-phase) interface dynamics, and formation of singularities. Here we demonstrate the importance of such flow modes on the partitioning dynamics at simple fracture intersections, with a combination of laboratory experiments, analytical solutions and numerical simulations using our newly developed massively parallel smoothed particle hydrodynamics (SPH) code. Flow modes heavily influence the "bypass" behavior of water flowing along a fracture junction. Flows favoring the formation of droplets exhibit a much stronger bypass capacity compared to rivulet flows, where nearly the whole fluid mass is initially stored within the horizontal fracture. This behavior is demonstrated for a multi-inlet laboratory setup where the inlet-specific flow rate is chosen so that either a droplet or rivulet flow persists. The effect of fluid buffering within the horizontal fracture is presented in terms of dimensionless fracture inflow so that characteristic scaling regimes can be recovered. For both cases (rivulets and droplets), flow within the horizontal fracture transitions into a Washburn regime until a critical threshold is reached and the bypass efficiency increases. For rivulet flows, the initial filling of the horizontal fracture is described by classical plug flow. Meanwhile, for droplet flows, a size-dependent partitioning behavior is observed, and the filling of the fracture takes longer.

Outcomes of a Research-Driven Laboratory and Literature Course Designed to Enhance Undergraduate Contributions to Original Research

ERIC Educational Resources Information Center

Rasche, Madeline E.

2004-01-01

This work describes outcomes of a research-driven advanced microbiology laboratory and literature research course intended to enhance undergraduate preparation for and contributions to original research. The laboratory section was designed to teach fundamental biochemistry and molecular biology techniques in the context of an original research…

Investigating the Effect of Argument-Driven Inquiry in Laboratory Instruction

ERIC Educational Resources Information Center

Demircioglu, Tuba; Ucar, Sedat

2015-01-01

The aim of this study is to investigate the effect of argument-driven inquiry (ADI) based laboratory instruction on the academic achievement, argumentativeness, science process skills, and argumentation levels of pre-service science teachers in the General Physics Laboratory III class. The study was conducted with 79 pre-service science teachers.…

Explosively driven two-shockwave tools with application to ejecta formation at the Los Alamos National Laboratory Proton Radiography Facility

NASA Astrophysics Data System (ADS)

Buttler, William

2013-06-01

We present the development of an explosively driven physics tool to generate two mostly uniaxial shockwaves. The tool is being used to extend single shockwave ejecta models to a subsequent shockwave event separated by a time interval on the order of a few microseconds. We explore the possibility of varying the amplitude of both the first and second shockwaves, and we apply the tool in experimental geometries on Sn with a surface roughness of Ra = 0 . 8 μ m. We then evaluate the tool further at the Los Alamos National Laboratory Proton Radiography (pRad) Facility in an application to Sn with larger scale perturbations of wavelength 550 μ m, and various amplitudes that gave wave-number amplitude products of η0 2 π / λ = { 3 / 4 , 1 / 2 , 1 / 4 , 1 / 8 } , where the perturbation amplitude is η0, and the wave-number k = 2 π / λ . The pRad data and velocimetry imply it should be possible to develop a second shock ejecta model based on unstable Richtmyer-Meshkov physics. In collaboration with David Oro, Fesseha Mariam, Alexander Saunders, Malcolm Andrews, Frank Cherne, James Hammerberg. Robert Hixson, Christopher Morris, Russell Olson, Dean Preston, Joseph Stone, Dale Tupa, and Wendy Vogan-McNeil, Los Alamos National Laboratory,

High Efficiency Solar Thermochemical Reactor for Hydrogen Production.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDaniel, Anthony H.

2017-09-30

This research and development project is focused on the advancement of a technology that produces hydrogen at a cost that is competitive with fossil-based fuels for transportation. A twostep, solar-driven WS thermochemical cycle is theoretically capable of achieving an STH conversion ratio that exceeds the DOE target of 26% at a scale large enough to support an industrialized economy [1]. The challenge is to transition this technology from the laboratory to the marketplace and produce hydrogen at a cost that meets or exceeds DOE targets.

Observations of electron phase-space holes driven during magnetic reconnection in a laboratory plasma

NASA Astrophysics Data System (ADS)

Fox, W.; Porkolab, M.; Egedal, J.; Katz, N.; Le, A.

2012-03-01

This work presents detailed experimental observations of electron phase-space holes driven during magnetic reconnection events on the Versatile Toroidal Facility. The holes are observed to travel on the order of or faster than the electron thermal speed, and are of large size scale, with diameter of order 60 Debye lengths. In addition, they have 3D spheroidal structure with approximately unity aspect ratio. We estimate the direct anomalous resistivity due to ion interaction with the holes and find it to be too small to affect the reconnection rate; however, the holes may play a role in reining in a tail of accelerated electrons and they indicate the presence of other processes in the reconnection layer, such as electron energization and electron beam formation.

Role of Laboratory Plasma Experiments in exploring the Physics of Solar Eruptions

NASA Astrophysics Data System (ADS)

Tripathi, S.

2017-12-01

Solar eruptive events are triggered over a broad range of spatio-temporal scales by a variety of fundamental processes (e.g., force-imbalance, magnetic-reconnection, electrical-current driven instabilities) associated with arched magnetoplasma structures in the solar atmosphere. Contemporary research on solar eruptive events is at the forefront of solar and heliospheric physics due to its relevance to space weather. Details on the formation of magnetized plasma structures on the Sun, storage of magnetic energy in such structures over a long period (several Alfven transit times), and their impulsive eruptions have been recorded in numerous observations and simulated in computer models. Inherent limitations of space observations and uncontrolled nature of solar eruptions pose significant challenges in testing theoretical models and developing the predictive capability for space-weather. The pace of scientific progress in this area can be significantly boosted by tapping the potential of appropriately scaled laboratory plasma experiments to compliment solar observations, theoretical models, and computer simulations. To give an example, recent results from a laboratory plasma experiment on arched magnetic flux ropes will be presented and future challenges will be discussed. (Work supported by National Science Foundation, USA under award number 1619551)

Kinetics and Photochemistry of Ruthenium Bisbipyridine Diacetonitrile Complexes: An Interdisciplinary Inorganic and Physical Chemistry Laboratory Exercise.

PubMed

Rapp, Teresa L; Phillips, Susan R; Dmochowski, Ivan J

2016-12-13

The study of ruthenium polypyridyl complexes can be widely applied across disciplines in the undergraduate curriculum. Ruthenium photochemistry has advanced many fields including dye-sensitized solar cells, photoredox catalysis, light-driven water oxidation, and biological electron transfer. Equally promising are ruthenium polypyridyl complexes that provide a sterically bulky, photolabile moiety for transiently "caging" biologically active molecules. Photouncaging involves the use of visible (1-photon) or near-IR (2-photon) light to break one or more bonds between ruthenium and coordinated ligand(s), which can occur on short time scales and in high quantum yields. In this work we demonstrate the use of a model "caged" acetonitrile complex, Ru(2,2'-bipyridine) 2 (acetonitrile) 2 , or RuMeCN in an advanced synthesis and physical chemistry laboratory. Students made RuMeCN in an advanced synthesis laboratory course and performed UV-vis spectroscopy and electrochemistry. The following semester students investigated RuMeCN photolysis kinetics in a physical chemistry laboratory. These two exercises may also be combined to create a 2-week module in an advanced undergraduate laboratory course.

Kinetics and Photochemistry of Ruthenium Bisbipyridine Diacetonitrile Complexes: An Interdisciplinary Inorganic and Physical Chemistry Laboratory Exercise

PubMed Central

2016-01-01

The study of ruthenium polypyridyl complexes can be widely applied across disciplines in the undergraduate curriculum. Ruthenium photochemistry has advanced many fields including dye-sensitized solar cells, photoredox catalysis, light-driven water oxidation, and biological electron transfer. Equally promising are ruthenium polypyridyl complexes that provide a sterically bulky, photolabile moiety for transiently “caging” biologically active molecules. Photouncaging involves the use of visible (1-photon) or near-IR (2-photon) light to break one or more bonds between ruthenium and coordinated ligand(s), which can occur on short time scales and in high quantum yields. In this work we demonstrate the use of a model “caged” acetonitrile complex, Ru(2,2′-bipyridine)2(acetonitrile)2, or RuMeCN in an advanced synthesis and physical chemistry laboratory. Students made RuMeCN in an advanced synthesis laboratory course and performed UV–vis spectroscopy and electrochemistry. The following semester students investigated RuMeCN photolysis kinetics in a physical chemistry laboratory. These two exercises may also be combined to create a 2-week module in an advanced undergraduate laboratory course. PMID:28649139

Earthquakes in the Laboratory: Continuum-Granular Interactions

NASA Astrophysics Data System (ADS)

Ecke, Robert; Geller, Drew; Ward, Carl; Backhaus, Scott

2013-03-01

Earthquakes in nature feature large tectonic plate motion at large scales of 10-100 km and local properties of the earth on the scale of the rupture width, of the order of meters. Fault gouge often fills the gap between the large slipping plates and may play an important role in the nature and dynamics of earthquake events. We have constructed a laboratory scale experiment that represents a similitude scale model of this general earthquake description. Two photo-elastic plates (50 cm x 25 cm x 1 cm) confine approximately 3000 bi-disperse nylon rods (diameters 0.12 and 0.16 cm, height 1 cm) in a gap of approximately 1 cm. The plates are held rigidly along their outer edges with one held fixed while the other edge is driven at constant speed over a range of about 5 cm. The local stresses exerted on the plates are measured using their photo-elastic response, the local relative motions of the plates, i.e., the local strains, are determined by the relative motion of small ball bearings attached to the top surface, and the configurations of the nylon rods are investigated using particle tracking tools. We find that this system has properties similar to real earthquakes and are exploring these ``lab-quake'' events with the quantitative tools we have developed.

Fluid-Driven Deformation of a Soft Granular Material

NASA Astrophysics Data System (ADS)

MacMinn, Christopher W.; Dufresne, Eric R.; Wettlaufer, John S.

2015-01-01

Compressing a porous, fluid-filled material drives the interstitial fluid out of the pore space, as when squeezing water out of a kitchen sponge. Inversely, injecting fluid into a porous material can deform the solid structure, as when fracturing a shale for natural gas recovery. These poromechanical interactions play an important role in geological and biological systems across a wide range of scales, from the propagation of magma through Earth's mantle to the transport of fluid through living cells and tissues. The theory of poroelasticity has been largely successful in modeling poromechanical behavior in relatively simple systems, but this continuum theory is fundamentally limited by our understanding of the pore-scale interactions between the fluid and the solid, and these problems are notoriously difficult to study in a laboratory setting. Here, we present a high-resolution measurement of injection-driven poromechanical deformation in a system with granular microsctructure: We inject fluid into a dense, confined monolayer of soft particles and use particle tracking to reveal the dynamics of the multiscale deformation field. We find that a continuum model based on poroelasticity theory captures certain macroscopic features of the deformation, but the particle-scale deformation field exhibits dramatic departures from smooth, continuum behavior. We observe particle-scale rearrangement and hysteresis, as well as petal-like mesoscale structures that are connected to material failure through spiral shear banding.

Modal interactions between a large-wavelength inclined interface and small-wavelength multimode perturbations in a Richtmyer-Meshkov instability

NASA Astrophysics Data System (ADS)

McFarland, Jacob A.; Reilly, David; Black, Wolfgang; Greenough, Jeffrey A.; Ranjan, Devesh

2015-07-01

The interaction of a small-wavelength multimodal perturbation with a large-wavelength inclined interface perturbation is investigated for the reshocked Richtmyer-Meshkov instability using three-dimensional simulations. The ares code, developed at Lawrence Livermore National Laboratory, was used for these simulations and a detailed comparison of simulation results and experiments performed at the Georgia Tech Shock Tube facility is presented first for code validation. Simulation results are presented for four cases that vary in large-wavelength perturbation amplitude and the presence of secondary small-wavelength multimode perturbations. Previously developed measures of mixing and turbulence quantities are presented that highlight the large variation in perturbation length scales created by the inclined interface and the multimode complex perturbation. Measures are developed for entrainment, and turbulence anisotropy that help to identify the effects of and competition between each perturbations type. It is shown through multiple measures that before reshock the flow processes a distinct memory of the initial conditions that is present in both large-scale-driven entrainment measures and small-scale-driven mixing measures. After reshock the flow develops to a turbulentlike state that retains a memory of high-amplitude but not low-amplitude large-wavelength perturbations. It is also shown that the high-amplitude large-wavelength perturbation is capable of producing small-scale mixing and turbulent features similar to the small-wavelength multimode perturbations.

Quantifying the dynamic density driven convection in high permeability packed beds.

PubMed

Teng, Ying; Jiang, Lanlan; Fan, Yingting; Liu, Yu; Wang, Dayong; Abudula, Abuliti; Song, Yongchen

2017-06-01

The density driven convection phenomenon is expected to have a significant and positive role in CO 2 geological storage capacity and safety. The onset and development of density-driven convective on the core scale is critical to understand the mass transfer mechanism. In this paper, laboratory experiments were conducted to investigate the density-driven convective in a vertical tube. The deuterium oxide (D 2 O)/manganese chloride (MnCl 2 ) water solution in water or brine were as an analog for CO 2 -rich brine in original brine. Experiments are repeated with variations in permeability to vary the characteristic Rayleigh number. Based on the MRI technology, the intensity images showed the interface clearly, reflecting the transition from diffusion to convective. With the echo-multi-slice pulse sequence method, the intensity images can be obtained as 2min 8s. For the denser fluid pairs, fingers appeared, propagated, coalesced and multi-fingers formed. The finger growth rate of the convective was visualized as three distinct periods: rising, stable and declining. Detailed information regarding the wave number, wave length, onset time and mixing time as functions of Rayleigh number are developed. Copyright © 2017 Elsevier Inc. All rights reserved.

Incorporating Scale-Dependent Fracture Stiffness for Improved Reservoir Performance Prediction

NASA Astrophysics Data System (ADS)

Crawford, B. R.; Tsenn, M. C.; Homburg, J. M.; Stehle, R. C.; Freysteinson, J. A.; Reese, W. C.

2017-12-01

We present a novel technique for predicting dynamic fracture network response to production-driven changes in effective stress, with the potential for optimizing depletion planning and improving recovery prediction in stress-sensitive naturally fractured reservoirs. A key component of the method involves laboratory geomechanics testing of single fractures in order to develop a unique scaling relationship between fracture normal stiffness and initial mechanical aperture. Details of the workflow are as follows: tensile, opening mode fractures are created in a variety of low matrix permeability rocks with initial, unstressed apertures in the micrometer to millimeter range, as determined from image analyses of X-ray CT scans; subsequent hydrostatic compression of these fractured samples with synchronous radial strain and flow measurement indicates that both mechanical and hydraulic aperture reduction varies linearly with the natural logarithm of effective normal stress; these stress-sensitive single-fracture laboratory observations are then upscaled to networks with fracture populations displaying frequency-length and length-aperture scaling laws commonly exhibited by natural fracture arrays; functional relationships between reservoir pressure reduction and fracture network porosity, compressibility and directional permeabilities as generated by such discrete fracture network modeling are then exported to the reservoir simulator for improved naturally fractured reservoir performance prediction.

Materials for stem cell factories of the future

NASA Astrophysics Data System (ADS)

Celiz, Adam D.; Smith, James G. W.; Langer, Robert; Anderson, Daniel G.; Winkler, David A.; Barrett, David A.; Davies, Martyn C.; Young, Lorraine E.; Denning, Chris; Alexander, Morgan R.

2014-06-01

Polymeric substrates are being identified that could permit translation of human pluripotent stem cells from laboratory-based research to industrial-scale biomedicine. Well-defined materials are required to allow cell banking and to provide the raw material for reproducible differentiation into lineages for large-scale drug-screening programs and clinical use. Yet more than 1 billion cells for each patient are needed to replace losses during heart attack, multiple sclerosis and diabetes. Producing this number of cells is challenging, and a rethink of the current predominant cell-derived substrates is needed to provide technology that can be scaled to meet the needs of millions of patients a year. In this Review, we consider the role of materials discovery, an emerging area of materials chemistry that is in large part driven by the challenges posed by biologists to materials scientists.

Operation and reactivity measurements of an accelerator driven subcritical TRIGA reactor

NASA Astrophysics Data System (ADS)

O'Kelly, David Sean

Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring.

Design of laboratory experiments to study photoionization fronts driven by thermal sources

DOE PAGES

Drake, R. P.; Hazak, G.; Keiter, P. A.; ...

2016-12-20

This study analyzes the requirements of a photoionization-front experiment that could be driven in the laboratory, using thermal sources to produce the necessary flux of ionizing photons. It reports several associated conclusions. Such experiments will need to employ the largest available facilities, capable of delivering many kJ to MJ of energy to an x-ray source. They will use this source to irradiate a volume of neutral gas, likely of N, on a scale of a few mm to a few cm, increasing with source energy. For a gas pressure of several to ten atmospheres at room temperature, and a sourcemore » temperature near 100 eV, one will be able to drive a photoionization front through a system of tens to hundreds of photon mean free paths. The front should make the familiar transition from the so-called R-Type to D-Type as the radiation flux diminishes with distance. The N is likely to reach the He-like state. Preheating from the energetic photons appears unlikely to become large enough to alter the essential dynamics of the front beyond some layer near the surface. For well-chosen experimental conditions, competing energy transport mechanisms are small.« less

DESIGN OF LABORATORY EXPERIMENTS TO STUDY PHOTOIONIZATION FRONTS DRIVEN BY THERMAL SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drake, R. P.; Keiter, P. A.; Davis, J. S.

2016-12-20

This paper analyzes the requirements of a photoionization-front experiment that could be driven in the laboratory, using thermal sources to produce the necessary flux of ionizing photons. It reports several associated conclusions. Such experiments will need to employ the largest available facilities, capable of delivering many kJ to MJ of energy to an X-ray source. They will use this source to irradiate a volume of neutral gas, likely of N, on a scale of a few mm to a few cm, increasing with source energy. For a gas pressure of several to ten atmospheres at room temperature, and a sourcemore » temperature near 100 eV, one will be able to drive a photoionization front through a system of tens to hundreds of photon mean free paths. The front should make the familiar transition from the so-called R-Type to D-Type as the radiation flux diminishes with distance. The N is likely to reach the He-like state. Preheating from the energetic photons appears unlikely to become large enough to alter the essential dynamics of the front beyond some layer near the surface. For well-chosen experimental conditions, competing energy transport mechanisms are small.« less

Influence of Test Section Geometry on the Blast Environment in an Explosively Driven Conical Shock Tube

DTIC Science & Technology

2018-03-30

ARL-TR-8335•MAR 2018 US Army Research Laboratory Influence of Test Section Geometry on theBlast Environment in an Explosively DrivenConical Shock...ARL-TR-8335•MAR 2018 US Army Research Laboratory Influence of Test Section Geometry on theBlast Environment in an Explosively DrivenConical Shock...Tube by Joel B Stewart Weapons and Materials Research Directorate, ARL Approved for public release; distribution is unlimited. REPORT DOCUMENTATION

An Hypothesis-Driven, Molecular Phylogenetics Exercise for College Biology Students

ERIC Educational Resources Information Center

Parker, Joel D.; Ziemba, Robert E.; Cahan, Sara Helms; Rissing, Steven W.

2004-01-01

This hypothesis-driven laboratory exercise teaches how DNA evidence can be used to investigate an organism's evolutionary history while providing practical modeling of the fundamental processes of gene transcription and translation. We used an inquiry-based approach to construct a laboratory around a nontrivial, open-ended evolutionary question…

Geoscience Meets Social Science: A Flexible Data Driven Approach for Developing High Resolution Population Datasets at Global Scale

NASA Astrophysics Data System (ADS)

Rose, A.; McKee, J.; Weber, E.; Bhaduri, B. L.

2017-12-01

Leveraging decades of expertise in population modeling, and in response to growing demand for higher resolution population data, Oak Ridge National Laboratory is now generating LandScan HD at global scale. LandScan HD is conceived as a 90m resolution population distribution where modeling is tailored to the unique geography and data conditions of individual countries or regions by combining social, cultural, physiographic, and other information with novel geocomputation methods. Similarities among these areas are exploited in order to leverage existing training data and machine learning algorithms to rapidly scale development. Drawing on ORNL's unique set of capabilities, LandScan HD adapts highly mature population modeling methods developed for LandScan Global and LandScan USA, settlement mapping research and production in high-performance computing (HPC) environments, land use and neighborhood mapping through image segmentation, and facility-specific population density models. Adopting a flexible methodology to accommodate different geographic areas, LandScan HD accounts for the availability, completeness, and level of detail of relevant ancillary data. Beyond core population and mapped settlement inputs, these factors determine the model complexity for an area, requiring that for any given area, a data-driven model could support either a simple top-down approach, a more detailed bottom-up approach, or a hybrid approach.

Dynamo-driven plasmoid formation from a current-sheet instability

DOE PAGES

Ebrahimi, F.

2016-12-15

Axisymmetric current-carrying plasmoids are formed in the presence of nonaxisymmetric fluctuations during nonlinear three-dimensional resistive MHD simulations in a global toroidal geometry. In this study, we utilize the helicity injection technique to form an initial poloidal flux in the presence of a toroidal guide field. As helicity is injected, two types of current sheets are formed from the oppositely directed field lines in the injector region (primary reconnecting current sheet), and the poloidal flux compression near the plasma edge (edge current sheet). We first find that nonaxisymmetric fluctuations arising from the current-sheet instability isolated near the plasma edge have tearingmore » parity but can nevertheless grow fast (on the poloidal Alfven time scale). These modes saturate by breaking up the current sheet. Second, for the first time, a dynamo poloidal flux amplification is observed at the reconnection site (in the region of the oppositely directed magnetic field). This fluctuation-induced flux amplification increases the local Lundquist number, which then triggers a plasmoid instability and breaks the primary current sheet at the reconnection site. Finally, the plasmoids formation driven by large-scale flux amplification, i.e., a large-scale dynamo, observed here has strong implications for astrophysical reconnection as well as fast reconnection events in laboratory plasmas.« less

Advanced CO 2 Leakage Mitigation using Engineered Biomineralization Sealing Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spangler, Lee; Cunningham, Alfred; Phillips, Adrienne

2015-03-31

This research project addresses one of the goals of the DOE Carbon Sequestration Program (CSP). The CSP core R&D effort is driven by technology and is accomplished through laboratory and pilot scale research aimed at new technologies for greenhouse gas mitigation. Accordingly, this project was directed at developing novel technologies for mitigating unwanted upward leakage of carbon dioxide (CO 2) injected into the subsurface as part of carbon capture and storage (CCS) activities. The technology developed by way of this research project is referred to as microbially induced calcite precipitation (MICP).

Demographics and Case Studies of Galactic Outflows in the Local Universe

NASA Astrophysics Data System (ADS)

Rupke, David

2017-07-01

Galactic outflows driven by both star formation and active black holes are an important driver of galaxy evolution. The local universe is a sensitive laboratory for understanding the scaling relations that characterize these winds and the physics that govern them. I will review what we know from statistical studies about the prevalance and properties of nearby galactic winds and how these properties depend on those of the host galaxy or power source. I will also highlight detailed case studies of key objects that illustrate the multiphase structure of these winds.

Learning to Argue and Arguing to Learn: Argument-Driven Inquiry as a Way to Help Undergraduate Chemistry Students Learn How to Construct Arguments and Engage in Argumentation during a Laboratory Course

ERIC Educational Resources Information Center

Walker, Joi Phelps; Sampson, Victor

2013-01-01

This study examines whether students enrolled in a general chemistry I laboratory course developed the ability to participate in scientific argumentation over the course of a semester. The laboratory activities that the students participated in during the course were designed using the Argument-Driven Inquiry (ADI) an instructional model. This…

Effective Rating Scale Development for Speaking Tests: Performance Decision Trees

ERIC Educational Resources Information Center

Fulcher, Glenn; Davidson, Fred; Kemp, Jenny

2011-01-01

Rating scale design and development for testing speaking is generally conducted using one of two approaches: the measurement-driven approach or the performance data-driven approach. The measurement-driven approach prioritizes the ordering of descriptors onto a single scale. Meaning is derived from the scaling methodology and the agreement of…

A laboratory facility for research on wind-driven rain intrusion in building envelope assemblies

Treesearch

Samuel V. Glass

2010-01-01

Moisture management is critical for durable, energy-efficient buildings. To address the need for research on wind-driven rain intrusion in wall assemblies, the U.S. Forest Products Laboratory is developing a new facility. This paper describes the underlying principle of this facility and its capabilities.

Problem-Based Learning and Creative Instructional Approaches for Laboratory Exercises in Introductory Crop Science

ERIC Educational Resources Information Center

Teplitski, Max; McMahon, Margaret J.

2006-01-01

The implementation of problem-based learning (PBL) and other inquiry-driven educational techniques is often resisted by both faculty and students, who may not be comfortable with this learning/instructional style. We present here a hybrid approach, which combines elements of expository education with inquiry-driven laboratory exercises and…

MHD scaling: from astrophysics to the laboratory

NASA Astrophysics Data System (ADS)

Ryutov, Dmitri

2000-10-01

During the last few years, considerable progress has been made in simulating astrophysical phenomena in laboratory experiments with high power lasers [1]. Astrophysical phenomena that have drawn particular interest include supernovae explosions; young supernova remnants; galactic jets; the formation of fine structures in late supernova remnants by instabilities; and the ablation driven evolution of molecular clouds illuminated by nearby bright stars, which may affect star formation. A question may arise as to what extent the laser experiments, which deal with targets of a spatial scale 0.01 cm and occur at a time scale of a few nanoseconds, can reproduce phenomena occurring at spatial scales of a million or more kilometers and time scales from hours to many years. Quite remarkably, if dissipative processes (like, e.g., viscosity, Joule dissipation, etc.) are subdominant in both systems, and the matter behaves as a polytropic gas, there exists a broad hydrodynamic similarity (the ``Euler similarity" of Ref. [2]) that allows a direct scaling of laboratory results to astrophysical phenomena. Following a review of relevant earlier work (in particular, [3]-[5]), discussion is presented of the details of the Euler similarity related to the presence of shocks and to a special case of a strong drive. After that, constraints stemming from possible development of small-scale turbulence are analyzed. Generalization of the Euler similarity to the case of a gas with spatially varying polytropic index is presented. A possibility of scaled simulations of ablation front dynamics is one more topic covered in this paper. It is shown that, with some additional constraints, a simple similarity exists. This, in particular, opens up the possibility of scaled laboratory simulation of the aforementioned ablation (photoevaporation) fronts. A nonlinear transformation [6] that establishes a duality between implosion and explosion processes is also discussed in the paper. 1. B.A. Remington et al., Phys. Plasmas, v.7, p. 1641 (2000); Science, v. 284, p. 1488 (1999). 2. D.D. Ryutov et al., Ap. J, v. 518, 821 (1999). 3. B.B. Kadomtsev. Sov. J. Plasma Phys., v. 1, p. 296 (1975). 4. J.W. Connor, J.B. Taylor. Nucl. Fus., v. 17, p. 377 (1977). 5. Q. Zhiang, M.J. Graham. Phys. Rev. Lett., v. 79, p. 2674 (1997). 6. L. O'C. Drury, J.T. Mendonca. Paper at 3rd Intern. Conf. on Laser. Astrophys., Rice Univ., Houston, 2000.

Experimental Investigation of the Influence of Small Scale Geological Heterogeneity on Capillary Trapping of CO2 Using Engineered Beadpacks

NASA Astrophysics Data System (ADS)

Ganesan Krishnamurthy, P.; Trevisan, L.; Meckel, T. A.

2017-12-01

During geologic CO2 sequestration, most of the storage domain far from the injection sites is likely to be dominated by buoyancy and capillary forces. Under such flow regimes, small scale geological heterogeneities have been shown to dampen plume migration rates and cause trapping beneath capillary barriers. To understand the impact of such heterogeneities on CO2 trapping processes experimentally, many core-scale and lab scale flow studies have been conducted. Reservoir cores are limited by the scale of investigation possible and most lab experiments are conducted in macroheterogeneous media constructed by arranging homogeneous units to represent heterogeneity. However, most natural sedimentary facies display heterogeneity at a hierarchy of scales, and heterogeneity at the mesoscale (mm to decimeters) goes unrepresented in laboratory experiments due to the difficulty in reproducibility. This work presents results from buoyancy driven migration experiments conducted at the meter scale using glass beads packed in a quasi 2D glass cell and complementary reduced physics simulations. We demonstrate a novel automated technique to build beadpacks with 2D heterogeneous sedimentary features in a reproducible manner. A fluid pair that mimics the phase density and viscosity contrasts, and interfacial tension of CO2-Brine at reservoir pressures and temperatures is employed for the flow experiments. Light transmission technique is used for visualization, and to calibrate and quantify saturation of the trapped non-wetting fluid during the experiments. Invasion Percolation is used to simulate the buoyancy driven flow. With the ability to generate different types of heterogeneous structures in a reproducible manner, and by comparing experiments and simulations, a systematic investigation of the effect of heterogeneity on capillary trapping becomes possible.

Hybridized Kibble-Zurek scaling in the driven critical dynamics across an overlapping critical region

NASA Astrophysics Data System (ADS)

Zhai, Liang-Jun; Wang, Huai-Yu; Yin, Shuai

2018-04-01

The conventional Kibble-Zurek scaling describes the scaling behavior in the driven dynamics across a single critical region. In this paper, we study the driven dynamics across an overlapping critical region, in which a critical region (Region A) is overlaid by another critical region (Region B). We develop a hybridized Kibble-Zurek scaling (HKZS) to characterize the scaling behavior in the driven process. According to the HKZS, the driven dynamics in the overlapping region can be described by the critical theories for both Region A and Region B simultaneously. This results in a constraint on the scaling function in the overlapping critical region. We take the quantum Ising chain in an imaginary longitudinal field as an example. In this model, the critical region of the Yang-Lee edge singularity and the critical region of the ferromagnetic-paramagnetic phase transition overlap with each other. We numerically confirm the HKZS by simulating the driven dynamics in this overlapping critical region. The HKZSs in other models are also discussed.

Intrawave sand suspension in the shoaling and surf zone of a field-scale laboratory beach

NASA Astrophysics Data System (ADS)

Brinkkemper, J. A.; de Bakker, A. T. M.; Ruessink, B. G.

2017-01-01

Short-wave sand transport in morphodynamic models is often based solely on the near-bed wave-orbital motion, thereby neglecting the effect of ripple-induced and surface-induced turbulence on sand transport processes. Here sand stirring was studied using measurements of the wave-orbital motion, turbulence, ripple characteristics, and sand concentration collected on a field-scale laboratory beach under conditions ranging from irregular nonbreaking waves above vortex ripples to plunging waves and bores above subdued bed forms. Turbulence and sand concentration were analyzed as individual events and in a wave phase-averaged sense. The fraction of turbulence events related to suspension events is relatively high (˜50%), especially beneath plunging waves. Beneath nonbreaking waves with vortex ripples, the sand concentration close to the bed peaks right after the maximum positive wave-orbital motion and shows a marked phase lag in the vertical, although the peak in concentration at higher elevations does not shift to beyond the positive to negative flow reversal. Under plunging waves, concentration peaks beneath the wavefront without any notable phase lags in the vertical. In the inner-surf zone (bores), the sand concentration remains phase coupled to positive wave-orbital motion, but the concentration decreases with distance toward the shoreline. On the whole, our observations demonstrate that the wave-driven suspended load transport is onshore and largest beneath plunging waves, while it is small and can also be offshore beneath shoaling waves. To accurately predict wave-driven sand transport in morphodynamic models, the effect of surface-induced turbulence beneath plunging waves should thus be included.

Simulation of large scale motions and small scale structures in planetary atmospheres and oceans: From laboratory to space experiments on ISS

NASA Astrophysics Data System (ADS)

Egbers, Christoph; Futterer, Birgit; Zaussinger, Florian; Harlander, Uwe

2014-05-01

Baroclinic waves are responsible for the transport of heat and momentum in the oceans, in the Earth's atmosphere as well as in other planetary atmospheres. The talk will give an overview on possibilities to simulate such large scale as well as co-existing small scale structures with the help of well defined laboratory experiments like the baroclinic wave tank (annulus experiment). The analogy between the Earth's atmosphere and the rotating cylindrical annulus experiment only driven by rotation and differential heating between polar and equatorial regions is obvious. From the Gulf stream single vortices seperate from time to time. The same dynamics and the co-existence of small and large scale structures and their separation can be also observed in laboratory experiments as in the rotating cylindrical annulus experiment. This experiment represents the mid latitude dynamics quite well and is part as a central reference experiment in the German-wide DFG priority research programme ("METSTRÖM", SPP 1276) yielding as a benchmark for lot of different numerical methods. On the other hand, those laboratory experiments in cylindrical geometry are limited due to the fact, that the surface and real interaction between polar and equatorial region and their different dynamics can not be really studied. Therefore, I demonstrate how to use the very successful Geoflow I and Geoflow II space experiment hardware on ISS with future modifications for simulations of small and large scale planetary atmospheric motion in spherical geometry with differential heating between inner and outer spheres as well as between the polar and equatorial regions. References: Harlander, U., Wenzel, J., Wang, Y., Alexandrov, K. & Egbers, Ch., 2012, Simultaneous PIV- and thermography measurements of partially blocked flow in a heated rotating annulus, Exp. in Fluids, 52 (4), 1077-1087 Futterer, B., Krebs, A., Plesa, A.-C., Zaussinger, F., Hollerbach, R., Breuer, D. & Egbers, Ch., 2013, Sheet-like and plume-like thermal flow in a spherical convection experiment performed under microgravity, J. Fluid Mech., vol. 75, p 647-683

Flows and Stratification of an Enclosure Containing Both Localised and Vertically Distributed Sources of Buoyancy

NASA Astrophysics Data System (ADS)

Partridge, Jamie; Linden, Paul

2013-11-01

We examine the flows and stratification established in a naturally ventilated enclosure containing both a localised and vertically distributed source of buoyancy. The enclosure is ventilated through upper and lower openings which connect the space to an external ambient. Small scale laboratory experiments were carried out with water as the working medium and buoyancy being driven directly by temperature differences. A point source plume gave localised heating while the distributed source was driven by a controllable heater mat located in the side wall of the enclosure. The transient temperatures, as well as steady state temperature profiles, were recorded and are reported here. The temperature profiles inside the enclosure were found to be dependent on the effective opening area A*, a combination of the upper and lower openings, and the ratio of buoyancy fluxes from the distributed and localised source Ψ =Bw/Bp . Industrial CASE award with ARUP.

Electrical conduction of organic ultrathin films evaluated by an independently driven double-tip scanning tunneling microscope.

PubMed

Takami, K; Tsuruta, S; Miyake, Y; Akai-Kasaya, M; Saito, A; Aono, M; Kuwahara, Y

2011-11-02

The electrical transport properties of organic thin films within the micrometer scale have been evaluated by a laboratory-built independently driven double-tip scanning tunneling microscope, operating under ambient conditions. The two tips were used as point contact electrodes, and current in the range from 0.1 pA to 100 nA flowing between the two tips through the material can be detected. We demonstrated two-dimensional contour mapping of the electrical resistance on a poly(3-octylthiophene) thin films as shown below. The obtained contour map clearly provided an image of two-dimensional electrical conductance between two point electrodes on the poly(3-octylthiophene) thin film. The conductivity of the thin film was estimated to be (1-8) × 10(-6) S cm(-1). Future prospects and the desired development of multiprobe STMs are also discussed.

Astrophysical Connections to Collapsing Radiative Shock Experiments

NASA Astrophysics Data System (ADS)

Reighard, A. B.; Hansen, J. F.; Bouquet, S.; Koenig, M.

2005-10-01

Radiative shocks occur in many high-energy density explosions, but prove difficult to create in laboratory experiments or to fully model with astrophysical codes. Low astrophysical densities combined with powerful explosions provide ideal conditions for producing radiative shocks. Here we describe an experiment significant to astrophysical shocks, which produces a driven, planar radiative shock in low density Xe gas. Including radiation effects precludes scaling experiments directly to astrophysical conditions via Euler equations, as can be done in purely hydrodynamic experiments. We use optical depth considerations to make comparisons between the driven shock in xenon and specific astrophysical phenomena. This planar shock may be subject to thin shell instabilities similar to those affecting the evolution of astrophysical shocks. This research was sponsored by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Research Grants DE-FG52-03NA00064, DE-FG53-2005-NA26014, and other grants and contracts.

Impact Forces from Tsunami-Driven Debris

NASA Astrophysics Data System (ADS)

Ko, H.; Cox, D. T.; Riggs, H.; Naito, C. J.; Kobayashi, M. H.; Piran Aghl, P.

2012-12-01

Debris driven by tsunami inundation flow has been known to be a significant threat to structures, yet we lack the constitutive equations necessary to predict debris impact force. The objective of this research project is to improve our understanding of, and predictive capabilities for, tsunami-driven debris impact forces on structures. Of special interest are shipping containers, which are virtually everywhere and which will float even when fully loaded. The forces from such debris hitting structures, for example evacuation shelters and critical port facilities such as fuel storage tanks, are currently not known. This research project focuses on the impact by flexible shipping containers on rigid columns and investigated using large-scale laboratory testing. Full-scale in-air collision experiments were conducted at Lehigh University with 20 ft shipping containers to experimentally quantify the nonlinear behavior of full scale shipping containers as they collide into structural elements. The results from the full scale experiments were used to calibrate computer models and used to design a series of simpler, 1:5 scale wave flume experiments at Oregon State University. Scaled in-air collision tests were conducted using 1:5 scale idealized containers to mimic the container behavior observed in the full scale tests and to provide a direct comparison to the hydraulic model tests. Two specimens were constructed using different materials (aluminum, acrylic) to vary the stiffness. The collision tests showed that at higher speeds, the collision became inelastic as the slope of maximum impact force/velocity decreased with increasing velocity. Hydraulic model tests were conducted using the 1:5 scaled shipping containers to measure the impact load by the containers on a rigid column. The column was instrumented with a load cell to measure impact forces, strain gages to measure the column deflection, and a video camera was used to provide the debris orientation and speed. The tsunami was modeled as a transient pulse command signal to the wavemaker to provide a low amplitude long wave. Results are expected to show the effect of the water on the debris collision by comparing water tests with the in-air tests. It is anticipated that the water will provide some combination of added mass and cushioning of the collision. Results will be compared with proposed equations for the new ASCE-7 standard and with numerical models at the University of Hawaii.

Implementation of Argument-Driven Inquiry as an Instructional Model in a General Chemistry Laboratory Course

ERIC Educational Resources Information Center

Kadayifci, Hakki; Yalcin-Celik, Ayse

2016-01-01

This study examined the effectiveness of Argument-Driven Inquiry (ADI) as an instructional model in a general chemistry laboratory course. The study was conducted over the course of ten experimental sessions with 125 pre-service science teachers. The participants' level of reflective thinking about the ADI activities, changes in their science…

Shaken, but not stirred: how vortical flow drives small-scale aggregations of gyrotactic phytoplankton

NASA Astrophysics Data System (ADS)

Barry, Michael; Durham, William; Climent, Eric; Stocker, Roman

2011-11-01

Coastal ocean observations reveal that motile phytoplankton form aggregations at the Kolmogorov scale (mm-cm), whereas non-motile cells do not. We propose a new mechanism for the formation of this small-scale patchiness based on the interplay of turbulence and gyrotactic motility. Counterintuitively, turbulence does not stir a plankton suspension to homogeneity but drives aggregations instead. Through controlled laboratory experiments we show that the alga Heterosigma akashiwo rapidly forms aggregations in a cavity-driven vortical flow that approximates Kolmogorov eddies. Gyrotactic motility is found to be the key ingredient for aggregation, as non-motile cells remain randomly distributed. Observations are in remarkable agreement with a 3D model, and the validity of this mechanism for generating patchiness has been extended to realistic turbulent flows using Direct Numerical Simulations. Because small-scale patchiness influences rates of predation, sexual reproduction, infection, and nutrient competition, this result indicates that gyrotactic motility can profoundly affect phytoplankton ecology.

Divergent Effects of Beliefs in Heaven and Hell on National Crime Rates

PubMed Central

Shariff, Azim F.; Rhemtulla, Mijke

2012-01-01

Though religion has been shown to have generally positive effects on normative ‘prosocial’ behavior, recent laboratory research suggests that these effects may be driven primarily by supernatural punishment. Supernatural benevolence, on the other hand, may actually be associated with less prosocial behavior. Here, we investigate these effects at the societal level, showing that the proportion of people who believe in hell negatively predicts national crime rates whereas belief in heaven predicts higher crime rates. These effects remain after accounting for a host of covariates, and ultimately prove stronger predictors of national crime rates than economic variables such as GDP and income inequality. Expanding on laboratory research on religious prosociality, this is the first study to tie religious beliefs to large-scale cross-national trends in pro- and anti-social behavior. PMID:22723927

Developing Large Scale Explosively Driven Flyer Experiments on Sand

NASA Astrophysics Data System (ADS)

Rehagen, Thomas; Kraus, Richard

2017-06-01

Measurements of the dynamic behavior of granular materials are of great importance to a variety of scientific and engineering applications, including planetary science, seismology, and construction and destruction. In addition, high quality data are needed to enhance our understanding of granular physics and improve the computational models used to simulate related physical processes. However, since there is a non-negligible grain size associated with these materials, experiments must be of a relatively large scale in order to capture the continuum response of the material and reduce errors associated with the finite grain size. We will present designs for explosively driven flyer experiments to make high accuracy measurements of the Hugoniot of sand (with a grain size of hundreds of microns). To achieve an accuracy of better than a few percent in density, we are developing a platform to measure the Hugoniot of samples several centimeters in thickness. We will present the target designs as well as coupled designs for the explosively launched flyer system. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Interchange Instability and Transport in Matter-Antimatter Plasmas

NASA Astrophysics Data System (ADS)

Kendl, Alexander; Danler, Gregor; Wiesenberger, Matthias; Held, Markus

2017-06-01

Symmetric electron-positron plasmas in inhomogeneous magnetic fields are intrinsically subject to interchange instability and transport. Scaling relations for the propagation velocity of density perturbations relevant to transport in isothermal magnetically confined electron-positron plasmas are deduced, including damping effects when Debye lengths are large compared to Larmor radii. The relations are verified by nonlinear full-F gyrofluid computations. Results are analyzed with respect to planned magnetically confined electron-positron plasma experiments. The model is generalized to other matter-antimatter plasmas. Magnetized electron-positron-proton-antiproton plasmas are susceptible to interchange-driven local matter-antimatter separation, which can impede sustained laboratory magnetic confinement.

Interchange Instability and Transport in Matter-Antimatter Plasmas.

PubMed

Kendl, Alexander; Danler, Gregor; Wiesenberger, Matthias; Held, Markus

2017-06-09

Symmetric electron-positron plasmas in inhomogeneous magnetic fields are intrinsically subject to interchange instability and transport. Scaling relations for the propagation velocity of density perturbations relevant to transport in isothermal magnetically confined electron-positron plasmas are deduced, including damping effects when Debye lengths are large compared to Larmor radii. The relations are verified by nonlinear full-F gyrofluid computations. Results are analyzed with respect to planned magnetically confined electron-positron plasma experiments. The model is generalized to other matter-antimatter plasmas. Magnetized electron-positron-proton-antiproton plasmas are susceptible to interchange-driven local matter-antimatter separation, which can impede sustained laboratory magnetic confinement.

Community Structure of Lithotrophically-Driven Hydrothermal Microbial Mats from the Mariana Arc and Back-Arc

PubMed Central

Hager, Kevin W.; Fullerton, Heather; Butterfield, David A.; Moyer, Craig L.

2017-01-01

The Mariana region exhibits a rich array of hydrothermal venting conditions in a complex geological setting, which provides a natural laboratory to study the influence of local environmental conditions on microbial community structure as well as large-scale patterns in microbial biogeography. We used high-throughput amplicon sequencing of the bacterial small subunit (SSU) rRNA gene from 22 microbial mats collected from four hydrothermally active locations along the Mariana Arc and back-arc to explore the structure of lithotrophically-based microbial mat communities. The vent effluent was classified as iron- or sulfur-rich corresponding with two distinct community types, dominated by either Zetaproteobacteria or Epsilonproteobacteria, respectively. The Zetaproteobacterial-based communities had the highest richness and diversity, which supports the hypothesis that Zetaproteobacteria function as ecosystem engineers creating a physical habitat within a chemical environment promoting enhanced microbial diversity. Gammaproteobacteria were also high in abundance within the iron-dominated mats and some likely contribute to primary production. In addition, we also compare sampling scale, showing that bulk sampling of microbial mats yields higher diversity than micro-scale sampling. We present a comprehensive analysis and offer new insights into the community structure and diversity of lithotrophically-driven microbial mats from a hydrothermal region associated with high microbial biodiversity. Our study indicates an important functional role of for the Zetaproteobacteria altering the mat habitat and enhancing community interactions and complexity. PMID:28970817

A Distributed Laboratory for Event-Driven Coastal Prediction and Hazard Planning

NASA Astrophysics Data System (ADS)

Bogden, P.; Allen, G.; MacLaren, J.; Creager, G. J.; Flournoy, L.; Sheng, Y. P.; Graber, H.; Graves, S.; Conover, H.; Luettich, R.; Perrie, W.; Ramakrishnan, L.; Reed, D. A.; Wang, H. V.

2006-12-01

The 2005 Atlantic hurricane season was the most active in recorded history. Collectively, 2005 hurricanes caused more than 2,280 deaths and record damages of over 100 billion dollars. Of the storms that made landfall, Dennis, Emily, Katrina, Rita, and Wilma caused most of the destruction. Accurate predictions of storm-driven surge, wave height, and inundation can save lives and help keep recovery costs down, provided the information gets to emergency response managers in time. The information must be available well in advance of landfall so that responders can weigh the costs of unnecessary evacuation against the costs of inadequate preparation. The SURA Coastal Ocean Observing and Prediction (SCOOP) Program is a multi-institution collaboration implementing a modular, distributed service-oriented architecture for real time prediction and visualization of the impacts of extreme atmospheric events. The modular infrastructure enables real-time prediction of multi- scale, multi-model, dynamic, data-driven applications. SURA institutions are working together to create a virtual and distributed laboratory integrating coastal models, simulation data, and observations with computational resources and high speed networks. The loosely coupled architecture allows teams of computer and coastal scientists at multiple institutions to innovate complex system components that are interconnected with relatively stable interfaces. The operational system standardizes at the interface level to enable substantial innovation by complementary communities of coastal and computer scientists. This architectural philosophy solves a long-standing problem associated with the transition from research to operations. The SCOOP Program thereby implements a prototype laboratory consistent with the vision of a national, multi-agency initiative called the Integrated Ocean Observing System (IOOS). Several service- oriented components of the SCOOP enterprise architecture have already been designed and implemented, including data archive and transport services, metadata registry and retrieval (catalog), resource management, and portal interfaces. SCOOP partners are integrating these at the service level and implementing reconfigurable workflows for several kinds of user scenarios, and are working with resource providers to prototype new policies and technologies for on-demand computing.

Fractured rock stress-permeability relationships from in situ data and effects of temperature and chemical-mechanical couplings

DOE PAGES

Rutqvist, J.

2014-09-19

The purpose of this paper is to (i) review field data on stress-induced permeability changes in fractured rock; (ii) describe estimation of fractured rock stress-permeability relationships through model calibration against such field data; and (iii) discuss observations of temperature and chemically mediated fracture closure and its effect on fractured rock permeability. The field data that are reviewed include in situ block experiments, excavation-induced changes in permeability around tunnels, borehole injection experiments, depth (and stress) dependent permeability, and permeability changes associated with a large-scale rock-mass heating experiment. Data show how the stress-permeability relationship of fractured rock very much depends on localmore » in situ conditions, such as fracture shear offset and fracture infilling by mineral precipitation. Field and laboratory experiments involving temperature have shown significant temperature-driven fracture closure even under constant stress. Such temperature-driven fracture closure has been described as thermal overclosure and relates to better fitting of opposing fracture surfaces at high temperatures, or is attributed to chemically mediated fracture closure related to pressure solution (and compaction) of stressed fracture surface asperities. Back-calculated stress-permeability relationships from field data may implicitly account for such effects, but the relative contribution of purely thermal-mechanical and chemically mediated changes is difficult to isolate. Therefore, it is concluded that further laboratory and in situ experiments are needed to increase the knowledge of the true mechanisms behind thermally driven fracture closure, and to further assess the importance of chemical-mechanical coupling for the long-term evolution of fractured rock permeability.« less

Fractured rock stress-permeability relationships from in situ data and effects of temperature and chemical-mechanical couplings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rutqvist, J.

The purpose of this paper is to (i) review field data on stress-induced permeability changes in fractured rock; (ii) describe estimation of fractured rock stress-permeability relationships through model calibration against such field data; and (iii) discuss observations of temperature and chemically mediated fracture closure and its effect on fractured rock permeability. The field data that are reviewed include in situ block experiments, excavation-induced changes in permeability around tunnels, borehole injection experiments, depth (and stress) dependent permeability, and permeability changes associated with a large-scale rock-mass heating experiment. Data show how the stress-permeability relationship of fractured rock very much depends on localmore » in situ conditions, such as fracture shear offset and fracture infilling by mineral precipitation. Field and laboratory experiments involving temperature have shown significant temperature-driven fracture closure even under constant stress. Such temperature-driven fracture closure has been described as thermal overclosure and relates to better fitting of opposing fracture surfaces at high temperatures, or is attributed to chemically mediated fracture closure related to pressure solution (and compaction) of stressed fracture surface asperities. Back-calculated stress-permeability relationships from field data may implicitly account for such effects, but the relative contribution of purely thermal-mechanical and chemically mediated changes is difficult to isolate. Therefore, it is concluded that further laboratory and in situ experiments are needed to increase the knowledge of the true mechanisms behind thermally driven fracture closure, and to further assess the importance of chemical-mechanical coupling for the long-term evolution of fractured rock permeability.« less

Experimental characterization of broadband electrostatic noise due to plasma compression

NASA Astrophysics Data System (ADS)

Dubois, Ami M.; Thomas, Edward, Jr.; Amatucci, William E.; Ganguli, Gurudas

2015-11-01

For a wide variety of laboratory and space plasma environments, theory states that plasmas are unstable to transverse shear flows over a very broad frequency range, where the shear scale length (LE) compared to the ion gyro-radius (ρi) determines the character of the shear-driven instability that may prevail. During active periods in the Earth's magnetosphere, such sheared flows are intensified and broadband electrostatic noise (BEN) is often observed by satellites traversing natural boundary layers. An interpenetrating magnetized plasma configuration is used to create a transverse velocity shear profile similar to that found at natural space plasma boundary layers. The continuous variation and the associated transition of the instability regimes driven by the shear flow mechanism are demonstrated in a single laboratory experiment. For the first time, broadband wave emission, which is correlated to increasing/decreasing stress (i.e., ρi/LE) on a plasma boundary layer, is found under controlled and repeatable conditions. This result provides evidence that the compression/relaxation of a plasma boundary layer leads to a BEN signature and holds out the promise for understanding the cause and effect of the in situ observation of BEN by satellites. This project was supported with funding from the U.S. Department of Energy, the Defense Threat Reduction Agency, and NRL Base Funds.

Free and forced convection in Earth's upper mantle

NASA Astrophysics Data System (ADS)

Hall, Paul S.

Convective motion within Earth's upper mantle occurs as a combination of two primary modes: (1) buoyant upwelling due to the formation of gravitational instabilities at thermochemical boundary layers, and (2) passive flow associated with the divergence of lithospheric plates at mid-ocean ridges and their re-entry into the mantle at subduction zones. The first mode is driven by variations in density and is therefore classified as 'free' convection. Examples of free convection within the Earth include the diapiric flow of hydrous and/or partially molten mantle at subduction zones and mantle plumes. The second mode, while ultimately driven by density on a global scale, can be treated kinematically on the scale of the upper mantle. This type of flow is designated 'forced' convection. On the scale of individual buoyant upwellings in the upper mantle, the forced convection associated with plate tectonics acts to modify the morphology of the flow associated with free convection. Regions in which such interactions occur are typically associated with transfer of significant quantities of both mass and energy (i.e., heat) between the deep interior and the surface of the Earth and thus afford a window into the dynamics of the Earth's interior. The dynamics and the consequences of the interaction between these two modes of convection is the focus of this dissertation. I have employed both laboratory and numerical modeling techniques to investigate the interaction between free and forced convection in this study. Each of these approaches has its own inherent strengths and weaknesses. These approaches are therefore complementary, and their use in combination is particularly powerful. I have focused on two examples interaction between free and forced convection in the upper mantle in this study. Chapter I considers the interaction between ascending diapirs of hydrous and/or partially molten mantle and flow in the mantle wedge at subduction zones using laboratory models. Chapter II and Chapter III consider the interaction between an ascending mantle plume and the large scale shear flow associated with the divergence of plates at a nearby ridge axis.

Developing High School Students' Self-Efficacy and Perceptions about Inquiry and Laboratory Skills through Argument-Driven Inquiry

ERIC Educational Resources Information Center

Eymur, Guluzar

2018-01-01

The present study investigated how students' self-efficacy changed after participation in four lab investigations that were designed on the basis of a new laboratory instructional strategy, namely, argument-driven inquiry (ADI). The study was conducted with 64 10th grade students from two intact classes in a public high school in the northeast of…

Variation of the hydraulic properties within gravity-driven deposits in basinal carbonates

NASA Astrophysics Data System (ADS)

Jablonska, D.; Zambrano, M.; Emanuele, T.; Di Celma, C.

2017-12-01

Deepwater gravity-driven deposits represent important stratigraphic heterogeneities within basinal sedimentary successions. A poor understanding of their distribution, internal architecture (at meso- and micro-scale) and hydraulic properties (porosity and permeability), may lead to unexpected compartmentalization issues in reservoir analysis. In this study, we examine gravity-driven deposits within the basinal-carbonate Maiolica Formation adjacent to the Apulian Carbonate Plaftorm, southern Italy. Maiolica formation is represented by horizontal layers of thin-bedded cherty pelagic limestones often intercalated by mass-transport deposits (slumps, debris-flow deposits) and calcarenites of diverse thickness (0.1 m - 40 m) and lateral extent (100 m - >500 m). Locally, gravity-driven deposits compose up to 60 % of the exposed succession. These deposits display broad array of internal architectures (from faulted and folded strata to conglomerates) and various texture. In order to further constrain the variation of the internal architectures and fracture distribution within gravity-driven deposits, field sedimentological and structural analyses were performed. To examine the texture and hydraulic properties of various lithofacies, the laboratory porosity measurements of suitable rock samples were undertaken. These data were supported by 3D pore network quantitative analysis of X-ray Computed microtomography (MicroCT) images performed at resolutions 1.25 and 2.0 microns. This analysis helped to describe the pores and grains geometrical and morphological properties (such as size, shape, specific surface area) and the hydraulic properties (porosity and permeability) of various lithofacies. The integration of the analyses allowed us to show how the internal architecture and the hydraulic properties vary in different types of gravity-driven deposits within the basinal carbonate succession.

Laser detonator development for test-firing applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munger, A. C.; Thomas, K. A.; Kennedy, J. E.

2004-01-01

Los Alamos National Laboratory has historically fielded two types of electro-explosive detonators. The exploding-bridgewire detonator (EBW) has an exploding wire as the initiating element, a low-density transfer charge and a high-density output pellet. The slapper detonator, or exploding-foil initiator (EFI), utilizes an exploding foil to drive a flying plate element into a high-density output pellet. The last twenty years has seen various research and development activities from many laboratories and manufacturing facilities around the world to develop laser-driven analogs of these devices, but to our knowledge none of those is in general use. Los Alamos is currently committed to designmore » and manufacture a laser analog to the long-standing, generic, general-purpose SE-1 EBW detonator, which is intended to provide increased safety in large-scale test-firing operations. This paper will discuss the major design parameters of this laser detonator and present some preliminary testing results.« less

Numerical modeling of laser-driven experiments aiming to demonstrate magnetic field amplification via turbulent dynamo

NASA Astrophysics Data System (ADS)

Tzeferacos, P.; Rigby, A.; Bott, A.; Bell, A. R.; Bingham, R.; Casner, A.; Cattaneo, F.; Churazov, E. M.; Emig, J.; Flocke, N.; Fiuza, F.; Forest, C. B.; Foster, J.; Graziani, C.; Katz, J.; Koenig, M.; Li, C.-K.; Meinecke, J.; Petrasso, R.; Park, H.-S.; Remington, B. A.; Ross, J. S.; Ryu, D.; Ryutov, D.; Weide, K.; White, T. G.; Reville, B.; Miniati, F.; Schekochihin, A. A.; Froula, D. H.; Gregori, G.; Lamb, D. Q.

2017-04-01

The universe is permeated by magnetic fields, with strengths ranging from a femtogauss in the voids between the filaments of galaxy clusters to several teragauss in black holes and neutron stars. The standard model behind cosmological magnetic fields is the nonlinear amplification of seed fields via turbulent dynamo to the values observed. We have conceived experiments that aim to demonstrate and study the turbulent dynamo mechanism in the laboratory. Here, we describe the design of these experiments through simulation campaigns using FLASH, a highly capable radiation magnetohydrodynamics code that we have developed, and large-scale three-dimensional simulations on the Mira supercomputer at the Argonne National Laboratory. The simulation results indicate that the experimental platform may be capable of reaching a turbulent plasma state and determining the dynamo amplification. We validate and compare our numerical results with a small subset of experimental data using synthetic diagnostics.

THz-driven zero-slippage IFEL scheme for phase space manipulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curry, E.; Fabbri, S.; Musumeci, P.

In this paper, we describe an inverse free electron laser (IFEL) interaction driven by a near single-cycle THz pulse that is group velocity-matched to an electron bunch inside a waveguide, allowing for a sustained interaction in a magnetic undulator. We discuss the application of this guided-THz IFEL technique for compression of a relativistic electron bunch and synchronization with the external laser pulse used to generate the THz pulse via optical rectification, as well as a laser-driven THz streaking diagnostic with the potential for femtosecond scale temporal resolution. Initial measurements of the THz waveform via an electro-optic sampling based technique confirm the predicted reduction of the group velocity, using a curved parallel plate waveguide, as a function of the varying aperture size of the guide. We also present the design of a proof-of-principle experiment based on the bunch parameters available at the UCLA PEGASUS laboratory. With amore » $$10\\,\\mathrm{MV}\\,{{\\rm{m}}}^{-1}$$ THz peak field, our simulation model predicts compression of a $$6\\,\\mathrm{MeV}$$ $$100\\,\\mathrm{fs}$$ electron beam by nearly an order of magnitude and a significant reduction of its initial timing jitter.« less

Electrically driving large magnetic Reynolds number flows on the Madison plasma dynamo experiment

NASA Astrophysics Data System (ADS)

Weisberg, David; Wallace, John; Peterson, Ethan; Endrezzi, Douglass; Forest, Cary B.; Desangles, Victor

2015-11-01

Electrically-driven plasma flows, predicted to excite a large-scale dynamo instability, have been generated in the Madison plasma dynamo experiment (MPDX), at the Wisconsin Plasma Astrophysics Laboratory. Numerical simulations show that certain topologies of these simply-connected flows may be optimal for creating a plasma dynamo and predict critical thresholds as low as Rmcrit =μ0 σLV = 250 . MPDX plasmas are shown to exceed this critical Rm , generating large (L = 1 . 4 m), warm (Te > 10 eV), unmagnetized (MA > 1) plasmas where Rm < 600 . Plasma flow is driven using ten thermally emissive LaB6 cathodes which generate a J × B torque in Helium plasmas. Detailed Mach probe measurements of plasma velocity for two flow topologies will be presented: edge-localized drive using the multi-cusp boundary field, and volumetric drive using an axial Helmholtz field. Radial velocity profiles show that edge-driven flow is established via ion viscosity but is limited by a volumetric neutral drag force (χ ~ 1 / (ντin)), and measurements of velocity shear compare favorably to Braginskii transport theory. Volumetric flow drive is shown to produce stronger velocity shear, and is characterized by the radial potential gradient as determined by global charge balance.

THz-driven zero-slippage IFEL scheme for phase space manipulation

DOE PAGES

Curry, E.; Fabbri, S.; Musumeci, P.; ...

2016-11-24

In this paper, we describe an inverse free electron laser (IFEL) interaction driven by a near single-cycle THz pulse that is group velocity-matched to an electron bunch inside a waveguide, allowing for a sustained interaction in a magnetic undulator. We discuss the application of this guided-THz IFEL technique for compression of a relativistic electron bunch and synchronization with the external laser pulse used to generate the THz pulse via optical rectification, as well as a laser-driven THz streaking diagnostic with the potential for femtosecond scale temporal resolution. Initial measurements of the THz waveform via an electro-optic sampling based technique confirm the predicted reduction of the group velocity, using a curved parallel plate waveguide, as a function of the varying aperture size of the guide. We also present the design of a proof-of-principle experiment based on the bunch parameters available at the UCLA PEGASUS laboratory. With amore » $$10\\,\\mathrm{MV}\\,{{\\rm{m}}}^{-1}$$ THz peak field, our simulation model predicts compression of a $$6\\,\\mathrm{MeV}$$ $$100\\,\\mathrm{fs}$$ electron beam by nearly an order of magnitude and a significant reduction of its initial timing jitter.« less

Wind driven erosion and the effects of particulate electrification

NASA Astrophysics Data System (ADS)

Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.; Rasmussen, K. R.

2012-09-01

Several related aspects of Aeolian activity are presently being studied in the laboratory, the most recent advances in this field will be presented. These include simulating wind driven erosion in the laboratory, quantifying erosion rates and the study of mineral change due to mechanical activation. Also advances in our understanding of the electrification of sand/dust particles is being made and how this phenomenon affects their behavior.

Effect of Unsaturated Flow Modes on Partitioning Dynamics of Gravity-Driven Flow at a Simple Fracture Intersection: Laboratory Study and Three-Dimensional Smoothed Particle Hydrodynamics Simulations

NASA Astrophysics Data System (ADS)

Kordilla, Jannes; Noffz, Torsten; Dentz, Marco; Geyer, Tobias; Tartakovsky, Alexandre M.

2017-11-01

In this work, we study gravity-driven flow of water in the presence of air on a synthetic surface intersected by a horizontal fracture and investigate the importance of droplet and rivulet flow modes on the partitioning behavior at the fracture intersection. We present laboratory experiments, three-dimensional smoothed particle hydrodynamics (SPH) simulations using a heavily parallelized code, and a theoretical analysis. The flow-rate-dependent mode switching from droplets to rivulets is observed in experiments and reproduced by the SPH model, and the transition ranges agree in SPH simulations and laboratory experiments. We show that flow modes heavily influence the "bypass" behavior of water flowing along a fracture junction. Flows favoring the formation of droplets exhibit a much stronger bypass capacity compared to rivulet flows, where nearly the whole fluid mass is initially stored within the horizontal fracture. The effect of fluid buffering within the horizontal fracture is presented in terms of dimensionless fracture inflow so that characteristic scaling regimes can be recovered. For both cases (rivulets and droplets), the flow within the horizontal fracture transitions into a Washburn regime until a critical threshold is reached and the bypass efficiency increases. For rivulet flows, the initial filling of the horizontal fracture is described by classical plug flow. Meanwhile, for droplet flows, a size-dependent partitioning behavior is observed, and the filling of the fracture takes longer. For the case of rivulet flow, we provide an analytical solution that demonstrates the existence of classical Washburn flow within the horizontal fracture.

Flow dynamics and salt transport in a coastal aquifer driven by a stratified saltwater body: Lab experiment and numerical modeling

NASA Astrophysics Data System (ADS)

Oz, Imri; Shalev, Eyal; Yechieli, Yoseph; Gavrieli, Ittai; Gvirtzman, Haim

2014-04-01

This paper examines the transient development and the steady-state configuration of groundwater within a coastal aquifer adjacent to a stratified saltwater body. Such systems consist of three different water types: the regional fresh groundwater, and low and high salinity brines forming the upper and lower water layers of the stratified water body, respectively. The dynamics, location and the geometry of the interfaces and the density-driven circulation flows that develop in the aquifer are examined using laboratory experiments and numerical modeling at the same scale. The results show that the transient intrusion of the different water bodies into the aquifer takes place at different rates, and that the locations of the interfaces between them change with time, before reaching steady-state. Under steady-state conditions both the model and the experiments show the existence of three interfaces between the three water types. The numerical model, which is calibrated against the salinity distribution and groundwater discharge rate in the laboratory experiments, allows the quantification of the flow rates and flow patterns within the aquifer. These flow patterns, which cannot be derived from laboratory experiments, show the transient development of three circulation cells which are confined between the three interfaces. These results confirm the hypothesis that has been previously suggested based solely on a steady-state numerical modeling defined by a conceptual understanding. Parametric analysis shows that the creation of three circulation cells and three interfaces is limited to certain conditions and defines the ranges for the creation of this unique system.

Maxwell Prize Talk: Scaling Laws for the Dynamical Plasma Phenomena

NASA Astrophysics Data System (ADS)

Ryutov, Livermore, Ca 94550, Usa, D. D.

2017-10-01

The scaling and similarity technique is a powerful tool for developing and testing reduced models of complex phenomena, including plasma phenomena. The technique has been successfully used in identifying appropriate simplified models of transport in quasistationary plasmas. In this talk, the similarity and scaling arguments will be applied to highly dynamical systems, in which temporal evolution of the plasma leads to a significant change of plasma dimensions, shapes, densities, and other parameters with respect to initial state. The scaling and similarity techniques for dynamical plasma systems will be presented as a set of case studies of problems from various domains of the plasma physics, beginning with collisonless plasmas, through intermediate collisionalities, to highly collisional plasmas describable by the single-fluid MHD. Basic concepts of the similarity theory will be introduced along the way. Among the results discussed are: self-similarity of Langmuir turbulence driven by a hot electron cloud expanding into a cold background plasma; generation of particle beams in disrupting pinches; interference between collisionless and collisional phenomena in the shock physics; similarity for liner-imploded plasmas; MHD similarities with an emphasis on the effect of small-scale (turbulent) structures on global dynamics. Relations between astrophysical phenomena and scaled laboratory experiments will be discussed.

Do you kiss your mother with that mouth? An authentic large-scale undergraduate research experience in mapping the human oral microbiome.

PubMed

Wang, Jack T H; Daly, Joshua N; Willner, Dana L; Patil, Jayee; Hall, Roy A; Schembri, Mark A; Tyson, Gene W; Hugenholtz, Philip

2015-05-01

Clinical microbiology testing is crucial for the diagnosis and treatment of community and hospital-acquired infections. Laboratory scientists need to utilize technical and problem-solving skills to select from a wide array of microbial identification techniques. The inquiry-driven laboratory training required to prepare microbiology graduates for this professional environment can be difficult to replicate within undergraduate curricula, especially in courses that accommodate large student cohorts. We aimed to improve undergraduate scientific training by engaging hundreds of introductory microbiology students in an Authentic Large-Scale Undergraduate Research Experience (ALURE). The ALURE aimed to characterize the microorganisms that reside in the healthy human oral cavity-the oral microbiome-by analyzing hundreds of samples obtained from student volunteers within the course. Students were able to choose from selective and differential culture media, Gram-staining, microscopy, as well as polymerase chain reaction (PCR) and 16S rRNA gene sequencing techniques, in order to collect, analyze, and interpret novel data to determine the collective oral microbiome of the student cohort. Pre- and postsurvey analysis of student learning gains across two iterations of the course (2012-2013) revealed significantly higher student confidence in laboratory skills following the completion of the ALURE (p < 0.05 using the Mann-Whitney U-test). Learning objectives on effective scientific communication were also met through effective student performance in laboratory reports describing the research outcomes of the project. The integration of undergraduate research in clinical microbiology has the capacity to deliver authentic research experiences and improve scientific training for large cohorts of undergraduate students.

Shock propagation in locally driven granular systems

NASA Astrophysics Data System (ADS)

Joy, Jilmy P.; Pathak, Sudhir N.; Das, Dibyendu; Rajesh, R.

2017-09-01

We study shock propagation in a system of initially stationary hard spheres that is driven by a continuous injection of particles at the origin. The disturbance created by the injection of energy spreads radially outward through collisions between particles. Using scaling arguments, we determine the exponent characterizing the power-law growth of this disturbance in all dimensions. The scaling functions describing the various physical quantities are determined using large-scale event-driven simulations in two and three dimensions for both elastic and inelastic systems. The results are shown to describe well the data from two different experiments on granular systems that are similarly driven.

Shock propagation in locally driven granular systems.

PubMed

Joy, Jilmy P; Pathak, Sudhir N; Das, Dibyendu; Rajesh, R

2017-09-01

We study shock propagation in a system of initially stationary hard spheres that is driven by a continuous injection of particles at the origin. The disturbance created by the injection of energy spreads radially outward through collisions between particles. Using scaling arguments, we determine the exponent characterizing the power-law growth of this disturbance in all dimensions. The scaling functions describing the various physical quantities are determined using large-scale event-driven simulations in two and three dimensions for both elastic and inelastic systems. The results are shown to describe well the data from two different experiments on granular systems that are similarly driven.

Model-driven discovery of underground metabolic functions in Escherichia coli.

PubMed

Guzmán, Gabriela I; Utrilla, José; Nurk, Sergey; Brunk, Elizabeth; Monk, Jonathan M; Ebrahim, Ali; Palsson, Bernhard O; Feist, Adam M

2015-01-20

Enzyme promiscuity toward substrates has been discussed in evolutionary terms as providing the flexibility to adapt to novel environments. In the present work, we describe an approach toward exploring such enzyme promiscuity in the space of a metabolic network. This approach leverages genome-scale models, which have been widely used for predicting growth phenotypes in various environments or following a genetic perturbation; however, these predictions occasionally fail. Failed predictions of gene essentiality offer an opportunity for targeting biological discovery, suggesting the presence of unknown underground pathways stemming from enzymatic cross-reactivity. We demonstrate a workflow that couples constraint-based modeling and bioinformatic tools with KO strain analysis and adaptive laboratory evolution for the purpose of predicting promiscuity at the genome scale. Three cases of genes that are incorrectly predicted as essential in Escherichia coli--aspC, argD, and gltA--are examined, and isozyme functions are uncovered for each to a different extent. Seven isozyme functions based on genetic and transcriptional evidence are suggested between the genes aspC and tyrB, argD and astC, gabT and puuE, and gltA and prpC. This study demonstrates how a targeted model-driven approach to discovery can systematically fill knowledge gaps, characterize underground metabolism, and elucidate regulatory mechanisms of adaptation in response to gene KO perturbations.

Modeling of Multi-Kilovolt X-ray Driven Ablation and Closure of Pinholes during Point-Projection Backlit Imaging

NASA Astrophysics Data System (ADS)

Bullock, A. B.; Landen, O. L.; Bradley, D. K.

2000-10-01

Pinhole-assisted point-projection backlighting of large samples with few µm pinholes can result in pinhole closure due to x-ray driven ablation of the high Z pinhole substrate, thereby potentially limiting the usefulness of this imaging method. The results of a previous study[1] using streaked 1-D backlit imaging of 25 mm W wires at the OMEGA laser are compared to simulations produced by HYADES, a 1-D Lagrangian hydrodynamics code. Interestingly, the observed image resolution stays fixed while the pinhole transmission drops within 1-2 ns, suggesting rapid filling by a long scale-length of low density substrate material. These results will be compared to time-dependent HYADES predictions of pinhole closure timescales and resolution. 1 A.B. bullock, D.K. Bradley, and O.L. Landen, to be published in RSI (2001). *This work was performed under the auspices of the U.S. Department of Energy by University of California/Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

Challenges in Measuring External Currents Driven by the Solar Wind-Magnetosphere Interaction

NASA Technical Reports Server (NTRS)

Le, Guan; Slavin, James A.; Pfaff, Robert F.

2014-01-01

In studying the Earth's geomagnetism, it has always been a challenge to separate magnetic fields from external currents originating from the ionosphere and magnetosphere. While the internal magnetic field changes very slowly in time scales of years and more, the ionospheric and magnetospheric current systems driven by the solar wind -magnetosphere interaction are very dynamic. They are intimately controlled by the ionospheric electrodynamics and ionospheremagnetosphere coupling. Single spacecraft observations are not able to separate their spatial and temporal variations, and thus to accurately describe their configurations. To characterize and understand the external currents, satellite observations require both good spatial and temporal resolutions. This paper reviews our observations of the external currents from two recent LEO satellite missions: Space Technology 5 (ST-5), NASA's first three-satellite constellation mission in LEO polar orbit, and Communications/Navigation Outage Forecasting System (C/NOFS), an equatorial satellite developed by US Air Force Research Laboratory. We present recommendations for future geomagnetism missions based on these observations.

The cyanobacterial circadian clock follows midday in vivo and in vitro

PubMed Central

Leypunskiy, Eugene; Lin, Jenny; Yoo, Haneul; Lee, UnJin; Dinner, Aaron R; Rust, Michael J

2017-01-01

Circadian rhythms are biological oscillations that schedule daily changes in physiology. Outside the laboratory, circadian clocks do not generally free-run but are driven by daily cues whose timing varies with the seasons. The principles that determine how circadian clocks align to these external cycles are not well understood. Here, we report experimental platforms for driving the cyanobacterial circadian clock both in vivo and in vitro. We find that the phase of the circadian rhythm follows a simple scaling law in light-dark cycles, tracking midday across conditions with variable day length. The core biochemical oscillator comprised of the Kai proteins behaves similarly when driven by metabolic pulses in vitro, indicating that such dynamics are intrinsic to these proteins. We develop a general mathematical framework based on instantaneous transformation of the clock cycle by external cues, which successfully predicts clock behavior under many cycling environments. DOI: http://dx.doi.org/10.7554/eLife.23539.001 PMID:28686160

Quantitative experimental monitoring of molecular diffusion in clay with positron emission tomography

NASA Astrophysics Data System (ADS)

Kulenkampff, Johannes; Zakhnini, Abdelhamid; Gründig, Marion; Lippmann-Pipke, Johanna

2016-08-01

Clay plays a prominent role as barrier material in the geosphere. The small particle sizes cause extremely small pore sizes and induce low permeability and high sorption capacity. Transport of dissolved species by molecular diffusion, driven only by a concentration gradient, is less sensitive to the pore size. Heterogeneous structures on the centimetre scale could cause heterogeneous effects, like preferential transport zones, which are difficult to assess. Laboratory measurements with diffusion cells yield limited information on heterogeneity, and pore space imaging methods have to consider scale effects. We established positron emission tomography (PET), applying a high-resolution PET scanner as a spatially resolved quantitative method for direct laboratory observation of the molecular diffusion process of a PET tracer on the prominent scale of 1-100 mm. Although PET is rather insensitive to bulk effects, quantification required significant improvements of the image reconstruction procedure with respect to Compton scatter and attenuation. The experiments were conducted with 22Na and 124I over periods of 100 and 25 days, respectively. From the images we derived trustable anisotropic diffusion coefficients and, in addition, we identified indications of preferential transport zones. We thus demonstrated the unique potential of the PET imaging modality for geoscientific process monitoring under conditions where other methods fail, taking advantage of the extremely high detection sensitivity that is typical of radiotracer applications.

Cyclonic circulation of Saturn's atmosphere due to tilted convection

NASA Astrophysics Data System (ADS)

Afanasyev, Y. D.; Zhang, Y.

2018-03-01

Saturn displays cyclonic vortices at its poles and the general atmospheric circulation at other latitudes is dominated by embedded zonal jets that display cyclonic circulation. The abundance of small-scale convective storms suggests that convection plays a role in producing and maintaining Saturn's atmospheric circulation. However, the dynamical influence of small-scale convection on Saturn's general circulation is not well understood. Here we present laboratory analogue experiments and propose that Saturn's cyclonic circulation can be explained by tilted convection in which buoyancy forces do not align with the planet's rotation axis. In our experiments—conducted with a cylindrical water tank that is heated at the bottom, cooled at the top and spun on a rotating table—warm rising plumes and cold sinking water generate small anticyclonic and cyclonic vortices that are qualitatively similar to Saturn's convective storms. Numerical simulations complement the experiments and show that this small-scale convection leads to large-scale cyclonic flow at the surface and anticyclonic circulation at the base of the fluid layer, with a polar vortex forming from the merging of smaller cyclonic storms that are driven polewards.

Intensity and angle-of-arrival spectra of laser light propagating through axially homogeneous buoyancy-driven turbulence.

PubMed

Pawar, Shashikant S; Arakeri, Jaywant H

2016-08-01

Frequency spectra obtained from the measurements of light intensity and angle of arrival (AOA) of parallel laser light propagating through the axially homogeneous, axisymmetric buoyancy-driven turbulent flow at high Rayleigh numbers in a long (length-to-diameter ratio of about 10) vertical tube are reported. The flow is driven by an unstable density difference created across the tube ends using brine and fresh water. The highest Rayleigh number is about 8×10⁹. The aim of the present work is to find whether the conventional Obukhov-Corrsin scaling or Bolgiano-Obukhov (BO) scaling is obtained for the intensity and AOA spectra in the case of light propagation in a buoyancy-driven turbulent medium. Theoretical relations for the frequency spectra of log amplitude and AOA fluctuations developed for homogeneous isotropic turbulent media are modified for the buoyancy-driven flow in the present case to obtain the asymptotic scalings for the high and low frequency ranges. For low frequencies, the spectra of intensity and vertical AOA fluctuations obtained from measurements follow BO scaling, while scaling for the spectra of horizontal AOA fluctuations shows a small departure from BO scaling.

Enhanced Forced Convection Heat Transfer using Small Scale Vorticity Concentrations Effected by Flow Driven, Aeroelastically Vibrating Reeds

DTIC Science & Technology

2016-08-03

insulated from behind (using an air gap) as shown in figure III.3-1c. Each of the heated side walls are instrumented with seven equally-spaced T-Type...AFRL-AFOSR-VA-TR-2016-0339 Enhanced convection heat transfer using small-scale vorticity concentrations effected by flow-driven, aeroelastically...public release. Enhanced Forced Convection Heat Transfer using Small-Scale Vorticity Concentrations Effected by Flow-Driven, Aeroelastically Vibrating

Hypothesis-Driven Laboratories: An Innovative Way to Foster Learning in Physiology Laboratory Courses

ERIC Educational Resources Information Center

Steury, Michael D.; Poteracki, James M.; Kelly, Kevin L.; Rennhack, Jonathan; Wehrwein, Erica A.

2016-01-01

Physiology instructors often are faced with the challenge of providing informative and educationally stimulating laboratories while trying to design them in such a way that encourages students to be actively involved in their own learning. With many laboratory experiments designed with simplicity and efficiency as the primary focus, it is…

Osmotically-driven membrane processes for water reuse and energy recovery

NASA Astrophysics Data System (ADS)

Achilli, Andrea

Osmotically-driven membrane processes are an emerging class of membrane separation processes that utilize concentrated brines to separate liquid streams. Their versatility of application make them an attractive alternative for water reuse and energy production/recovery. This work focused on innovative applications of osmotically-driven membrane processes. The novel osmotic membrane bioreactor (OMBR) system for water reuse was presented. Experimental results demonstrated high sustainable flux and relatively low reverse diffusion of solutes from the draw solution into the mixed liquor. Membrane fouling was minimal and controlled with osmotic backwashing. The OMBR system was found to remove greater than 99% of organic carbon and ammonium-nitrogen. Forward osmosis (FO) can employ different draw solution in its process. More than 500 inorganic compounds were screened as draw solution candidates, the desktop screening process resulted in 14 draw solutions suitable for FO applications. The 14 draw solutions were then tested in the laboratory to evaluate water flux and reverse salt diffusion through the membrane. Results indicated a wide range of water flux and reverse salt diffusion depending on the draw solution utilized. Internal concentration polarization was found to lower both water flux and reverse salt diffusion by reducing the draw solution concentration at the interface between the support and dense layer of the membrane. A small group of draw solutions was found to be most suitable for FO processes with currently available FO membranes. Another application of osmotically-driven membrane processes is pressure retarded osmosis (PRO). PRO was investigated as a viable source of renewable energy. A PRO model was developed to predict water flux and power density under specific experimental conditions. The predictive model was tested using experimental results from a bench-scale PRO system. Previous investigations of PRO were unable to verify model predictions due to the lack of suitable membranes and membrane modules. In this investigation, for the first time, the use of a custom-made laboratory-scale membrane module enabled the collection of experimental PRO data. Results obtained with a flat-sheet cellulose triacetate FO membrane and NaCl feed and draw solutions closely matched model predictions. Power density was substantially reduced due to internal concentration polarization in the asymmetric membrane and, to a lesser degree, to salt passage. External concentration polarization was found to exhibit a relatively small effect on reducing the osmotic pressure driving force. Using the predictive PRO model, optimal membrane characteristics and module configuration can be determined in order to design a system specifically tailored for PRO processes.

Convective dissolution of carbon dioxide in saline aquifers

NASA Astrophysics Data System (ADS)

Neufeld, Jerome A.; Hesse, Marc A.; Riaz, Amir; Hallworth, Mark A.; Tchelepi, Hamdi A.; Huppert, Herbert E.

2010-11-01

Geological carbon dioxide (CO2) storage is a means of reducing anthropogenic emissions. Dissolution of CO2 into the brine, resulting in stable stratification, increases storage security. The dissolution rate is determined by convection in the brine driven by the increase of brine density with CO2 saturation. We present a new analogue fluid system that reproduces the convective behaviour of CO2-enriched brine. Laboratory experiments and high-resolution numerical simulations show that the convective flux scales with the Rayleigh number to the 4/5 power, in contrast with a classical linear relationship. A scaling argument for the convective flux incorporating lateral diffusion from downwelling plumes explains this nonlinear relationship for the convective flux, provides a physical picture of high Rayleigh number convection in a porous medium, and predicts the CO2 dissolution rates in CO2 accumulations. These estimates of the dissolution rate show that convective dissolution can play an important role in enhancing storage security.

Imbibition with swelling: Capillary rise in thin deformable porous media

NASA Astrophysics Data System (ADS)

Kvick, Mathias; Martinez, D. Mark; Hewitt, Duncan R.; Balmforth, Neil J.

2017-07-01

The imbibition of a liquid into a thin deformable porous substrate driven by capillary suction is considered. The substrate is initially dry and has uniform porosity and thickness. Two-phase flow theory is used to describe how the liquid flows through the pore space behind the wetting front when out-of-plane deformation of the solid matrix is considered. Neglecting gravity and evaporation, standard shallow-layer scalings are used to construct a reduced model of the dynamics. The model predicts convergence to a self-similar behavior in all regions except near the wetting front, where a boundary layer arises whose structure narrows with the advance of the front. Over time, the rise height approaches the similarity scaling of t1 /2, as in the classical Washburn or BCLW law. The results are compared with a series of laboratory experiments using cellulose paper sheets, which provide qualitative agreement.

Control of Infectious Diseases in the Era of European Clinical Microbiology Laboratory Consolidation: New Challenges and Opportunities for the Patient and for Public Health Surveillance.

PubMed

Vandenberg, Olivier; Kozlakidis, Zisis; Schrenzel, Jacques; Struelens, Marc Jean; Breuer, Judith

2018-01-01

Many new innovative diagnostic approaches have been made available during the last 10 years with major impact on patient care and public health surveillance. In parallel, to enhance the cost-effectiveness of the clinical microbiology laboratories (CMLs), European laboratory professionals have streamlined their organization leading to amalgamation of activities and restructuring of their professional relationships with clinicians and public health specialists. Through this consolidation process, an operational model has emerged that combines large centralized clinical laboratories performing most tests on one high-throughput analytical platform connected to several distal laboratories dealing locally with urgent analyses at near point of care. The centralization of diagnostic services over a large geographical region has given rise to the concept of regional-scale "microbiology laboratories network." Although the volume-driven cost savings associated with such laboratory networks seem self-evident, the consequence(s) for the quality of patient care and infectious disease surveillance and control remain less obvious. In this article, we describe the range of opportunities that the changing landscape of CMLs in Europe can contribute toward improving the quality of patient care but also the early detection and enhanced surveillance of public health threats caused by infectious diseases. The success of this transformation of health services is reliant on the appropriate preparation in terms of staff, skills, and processes that would be inclusive of stakeholders. In addition, rigorous metrics are needed to set out more concrete laboratory service performance objectives and assess the expected benefits to society in terms of saving lives and preventing diseases.

Plasma Accelerators Race to 10 GeV and Beyond

NASA Astrophysics Data System (ADS)

Katsouleas, Tom

2005-10-01

This paper reviews the concepts, recent progress and current challenges for realizing the tremendous electric fields in relativistic plasma waves for applications ranging from tabletop particle accelerators to high-energy physics. Experiments in the 90's on laser-driven plasma wakefield accelerators at several laboratories around the world demonstrated the potential for plasma wakefields to accelerate intense bunches of self-trapped particles at rates as high as 100 GeV/m in mm-scale gas jets. These early experiments offered impressive gradients but large energy spread (100%) and short interaction lengths. Major breakthroughs have recently occurred on both fronts. Three groups (LBL-US, LOA-France and RAL-UK) have now entered a new regime of laser wakefield acceleration resulting in 100 MeV mono-energetic beams with up to nanoCoulombs of charge and very small angular spread. Simulations suggest that current lasers are just entering this new regime, and the scaling to higher energies appears attractive. In parallel with the progress in laser-driven wakefields, particle-beam driven wakefield accelerators are making large strides. A series of experiments using the 30 GeV beam of the Stanford Linear Accelerator Center (SLAC) has demonstrated high-gradient acceleration of electrons and positrons in meter-scale plasmas. The UCLA/USC/SLAC collaboration has accelerated electrons beyond 1 GeV and is aiming at 10 GeV in 30 cm as the next step toward a ``plasma afterburner,'' a concept for doubling the energy of a high-energy collider in a few tens of meters of plasma. In addition to wakefield acceleration, these and other experiments have demonstrated the rich physics bounty to be reaped from relativistic beam-plasma interactions. This includes plasma lenses capable of focusing particle beams to the highest density ever produced, collective radiation mechanisms capable of generating high-brightness x-ray beams, collective refraction of particles at a plasma interface, and acceleration of intense proton beams from laser-irradiated foils.

Quantifying the role of trees as Critical Zone architects employing crowbars, wedges and other tools of soil production

NASA Astrophysics Data System (ADS)

Marshall, J. A.; Anderson, R. S.; Dawson, T. E.; Dietrich, W. E.; Sklar, L. S.

2016-12-01

The Critical Zone (CZ) supports diverse functions such as water routing, net primary productivity, carbon storage, and mineral supplies for the geochemical reactor. The detailed architecture of the CZ, and the pace at which it evolves, are strongly influenced by the rate at which bedrock is converted to mobile material (the soil production rate). While trees serve as rebar-like soil stabilizers over short time scales, over longer time scales tree-driven forces can damage, disrupt and detach bedrock, and hence play a key role in soil production. Root growth and tree throw then can both release rock from the underlying bedrock and contribute to the downslope transport of the mobile material. Thus, the physical mechanisms controlling tree-driven soil production may set the pace and style of both the production and transport of soil. However, we know little about how or how often trees damage rock, create fractures, or expand existing fractures in competent bedrock or saprolite. Measurement of the relevant forces at the bedrock-root interface is difficult. Here we present preliminary data from a novel technique that allows us to document both root-growth and wind-induced forces at the rock-root interface at the Boulder Creek and Eel River Critical Zone Observatories. By combining force measurements with wind speed and wind-driven tree sway data, we quantify the magnitude and frequency of tree-driven soil-production mechanisms at two sites with differing climates and lithologies. In addition, we describe physical experiments in which we grow tree roots within pre-instrumented, manufactured fractures to measure the potential for root growth forces to induce crack tip propagation, to induce stress fatigue or to exceed the tensile or compressive strength of weak bedrock. Combined, these field and laboratory measurements provide mechanistic insight into the roles of trees as architects of the Critical Zone.

A Multi-mission Event-Driven Component-Based System for Support of Flight Software Development, ATLO, and Operations first used by the Mars Science Laboratory (MSL) Project

NASA Technical Reports Server (NTRS)

Dehghani, Navid; Tankenson, Michael

2006-01-01

This paper details an architectural description of the Mission Data Processing and Control System (MPCS), an event-driven, multi-mission ground data processing components providing uplink, downlink, and data management capabilities which will support the Mars Science Laboratory (MSL) project as its first target mission. MPCS is developed based on a set of small reusable components, implemented in Java, each designed with a specific function and well-defined interfaces. An industry standard messaging bus is used to transfer information among system components. Components generate standard messages which are used to capture system information, as well as triggers to support the event-driven architecture of the system. Event-driven systems are highly desirable for processing high-rate telemetry (science and engineering) data, and for supporting automation for many mission operations processes.

Observations of nonlinear and nonuniform kink dynamics in a laboratory flux rope

NASA Astrophysics Data System (ADS)

Sears, J.; Intrator, T.; Feng, Y.; Swan, H.; Gao, K.; Chapdelaine, L.

2013-12-01

A plasma column with axial magnetic field and current has helically twisted field lines. When current density in the column exceeds the kink instability threshold this magnetic configuration becomes unstable. Flux ropes in the solar wind and some solar prominences exhibit this topology, with their dynamics strongly and nonlinearly coupled to the ratio of axial current to magnetic field. The current-driven kink mode is ubiquitous in laboratory plasmas and well suited to laboratory study. In the Reconnection Scaling Experiment (RSX), nonlinear stability properties beyond the simple perturbative kink model are observed and readily diagnosed. We use a plasma gun to generate a single plasma column 0.50 m in length, in which we then drive an axial plasma current at the limit of marginal kink stability. With plasma current maintained at this threshold, we observe a deformation to a new dynamic equilibrium with finite gyration amplitude, where the currents and magnetic fields that support the force balance have surprising axial structure. Three dimensional measurements of magnetic field, plasma density, plasma potential, and ion flow velocity in the deformed plasma column show variation in the axial direction of the instability parameter and in the terms of the momentum equation. Likewise the pitch of the kink is measured to be nonuniform over the column length. In addition there is a return current antiparallel to the driven plasma current at distances up to 0.30 m from the gun that also modifies the force balance. These axial inhomogeneities, which are not considered in the model of an ideal kink, may be the terms that allow the deformed equilibrium of the RSX plasma to exist. Supported by DOE Office of Fusion Energy Sciences under LANS contract DE-AC52-06NA25369, NASA Geospace NNHIOA044I, Basic. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Using a Time-Driven Activity-Based Costing Model To Determine the Actual Cost of Services Provided by a Transgenic Core.

PubMed

Gerwin, Philip M; Norinsky, Rada M; Tolwani, Ravi J

2018-03-01

Laboratory animal programs and core laboratories often set service rates based on cost estimates. However, actual costs may be unknown, and service rates may not reflect the actual cost of services. Accurately evaluating the actual costs of services can be challenging and time-consuming. We used a time-driven activity-based costing (ABC) model to determine the cost of services provided by a resource laboratory at our institution. The time-driven approach is a more efficient approach to calculating costs than using a traditional ABC model. We calculated only 2 parameters: the time required to perform an activity and the unit cost of the activity based on employee cost. This method allowed us to rapidly and accurately calculate the actual cost of services provided, including microinjection of a DNA construct, microinjection of embryonic stem cells, embryo transfer, and in vitro fertilization. We successfully implemented a time-driven ABC model to evaluate the cost of these services and the capacity of labor used to deliver them. We determined how actual costs compared with current service rates. In addition, we determined that the labor supplied to conduct all services (10,645 min/wk) exceeded the practical labor capacity (8400 min/wk), indicating that the laboratory team was highly efficient and that additional labor capacity was needed to prevent overloading of the current team. Importantly, this time-driven ABC approach allowed us to establish a baseline model that can easily be updated to reflect operational changes or changes in labor costs. We demonstrated that a time-driven ABC model is a powerful management tool that can be applied to other core facilities as well as to entire animal programs, providing valuable information that can be used to set rates based on the actual cost of services and to improve operating efficiency.

Turbulence-enhanced bottom melting of a horizontal glacier--lake interface

NASA Astrophysics Data System (ADS)

Keitzl, T.; Mellado, J. P.; Notz, D.

2014-12-01

We use laboratory tank experiments and direct numerical simulations to investigate the meltrates of a horizontal bottom glacier--lake interface as a function of lake temperature. Existing parameterisations of such meltrates are usually based on empirical fits to field observations. To understand the meltrates of an ice--water interface more systematically we study an idealised system in terms of its temperature-driven buoyancy forcing. In such systems, the meltrate can be expressed analytically for a stable stratification. Here we investigate the unstable case and present how the meltrate depends on the lake temperature when the water beneath the ice is overturning and turbulent. We use laboratory tank experiments and direct numerical simulations to study an idealised ice--water boundary. The laboratory tank experiments provide robust observation-based mean-temperature profiles. The numerical simulations provide the full three-dimensional structure of the turbulent flow down to scales not accessible in the laboratory, with a minimum 0.2mm gridspacing. Our laboratory mean-temperature profiles agree well with the numerical simulations and lend credibility to our numerical setup. The structure of the turbulent flow in our simulations is well described by two self-similar subregions, a diffusion-dominated inner layer close to the ice and a turbulence-dominated outer layer far from the ice. We provide an explicit expression for the parameterisation of the meltrate of a horizontal glacier--lake interface as a function of lake temperature.

Agile data management for curation of genomes to watershed datasets

NASA Astrophysics Data System (ADS)

Varadharajan, C.; Agarwal, D.; Faybishenko, B.; Versteeg, R.

2015-12-01

A software platform is being developed for data management and assimilation [DMA] as part of the U.S. Department of Energy's Genomes to Watershed Sustainable Systems Science Focus Area 2.0. The DMA components and capabilities are driven by the project science priorities and the development is based on agile development techniques. The goal of the DMA software platform is to enable users to integrate and synthesize diverse and disparate field, laboratory, and simulation datasets, including geological, geochemical, geophysical, microbiological, hydrological, and meteorological data across a range of spatial and temporal scales. The DMA objectives are (a) developing an integrated interface to the datasets, (b) storing field monitoring data, laboratory analytical results of water and sediments samples collected into a database, (c) providing automated QA/QC analysis of data and (d) working with data providers to modify high-priority field and laboratory data collection and reporting procedures as needed. The first three objectives are driven by user needs, while the last objective is driven by data management needs. The project needs and priorities are reassessed regularly with the users. After each user session we identify development priorities to match the identified user priorities. For instance, data QA/QC and collection activities have focused on the data and products needed for on-going scientific analyses (e.g. water level and geochemistry). We have also developed, tested and released a broker and portal that integrates diverse datasets from two different databases used for curation of project data. The development of the user interface was based on a user-centered design process involving several user interviews and constant interaction with data providers. The initial version focuses on the most requested feature - i.e. finding the data needed for analyses through an intuitive interface. Once the data is found, the user can immediately plot and download data through the portal. The resulting product has an interface that is more intuitive and presents the highest priority datasets that are needed by the users. Our agile approach has enabled us to build a system that is keeping pace with the science needs while utilizing limited resources.

Inertial confinement fusion ablator physics experiments on Saturn and Nova

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, R.E.; Porter, J.L.; Chandler, G.A.

1997-05-01

The Saturn pulsed power accelerator [R. B. Spielman {ital et al.}, in {ital Proceedings of the 2nd International Conference on Dense} Z-{ital pinches}, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] at Sandia National Laboratories (SNL) and the Nova laser [J. T. Hunt and D. R. Speck, Opt. Eng. {bold 28}, 461 (1989)] at Lawrence Livermore National Laboratory (LLNL) have been used to explore techniques for studying the behavior of ablator material in x-ray radiation environments comparable in magnitude, spectrum, and duration to those thatmore » would be experienced in National Ignition Facility (NIF) hohlraums [J. D. Lindl, Phys. Plasmas {bold 2}, 3933 (1995)]. The large x-ray outputs available from the Saturn pulsed-power-driven z pinch have enabled us to drive hohlraums of full NIF ignition scale size at radiation temperatures and time scales comparable to those required for the low-power foot pulse of an ignition capsule. The high-intensity drives available in the Nova laser have allowed us to study capsule ablator physics in smaller-scale hohlraums at radiation temperatures and time scales relevant to the peak power pulse for an ignition capsule. Taken together, these experiments have pointed the way to possible techniques for testing radiation-hydrodynamics code predictions of radiation flow, opacity, equation of state, and ablator shock velocity over the range of radiation environments that will be encountered in a NIF hohlraum. {copyright} {ital 1997 American Institute of Physics.}« less

On the generation of magnetized collisionless shocks in the large plasma device

NASA Astrophysics Data System (ADS)

Schaeffer, D. B.; Winske, D.; Larson, D. J.; Cowee, M. M.; Constantin, C. G.; Bondarenko, A. S.; Clark, S. E.; Niemann, C.

2017-04-01

Collisionless shocks are common phenomena in space and astrophysical systems, and in many cases, the shocks can be modeled as the result of the expansion of a magnetic piston though a magnetized ambient plasma. Only recently, however, have laser facilities and diagnostic capabilities evolved sufficiently to allow the detailed study in the laboratory of the microphysics of piston-driven shocks. We review experiments on collisionless shocks driven by a laser-produced magnetic piston undertaken with the Phoenix laser laboratory and the Large Plasma Device at the University of California, Los Angeles. The experiments span a large parameter space in laser energy, background magnetic field, and ambient plasma properties that allow us to probe the physics of piston-ambient energy coupling, the launching of magnetosonic solitons, and the formation of subcritical shocks. The results indicate that piston-driven magnetized collisionless shocks in the laboratory can be characterized with a small set of dimensionless formation parameters that place the formation process in an organized and predictive framework.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeffer, D. B.; Winske, D.; Larson, D. J.

Collisionless shocks are common phenomena in space and astrophysical systems, and in many cases, the shocks can be modeled as the result of the expansion of a magnetic piston though a magnetized ambient plasma. Only recently, however, have laser facilities and diagnostic capabilities evolved sufficiently to allow the detailed study in the laboratory of the microphysics of piston-driven shocks. We review experiments on collisionless shocks driven by a laser-produced magnetic piston undertaken with the Phoenix laser laboratory and the Large Plasma Device at the University of California, Los Angeles. The experiments span a large parameter space in laser energy, backgroundmore » magnetic field, and ambient plasma properties that allow us to probe the physics of piston-ambient energy coupling, the launching of magnetosonic solitons, and the formation of subcritical shocks. Here, the results indicate that piston-driven magnetized collisionless shocks in the laboratory can be characterized with a small set of dimensionless formation parameters that place the formation process in an organized and predictive framework.« less

On the generation of magnetized collisionless shocks in the large plasma device

DOE PAGES

Schaeffer, D. B.; Winske, D.; Larson, D. J.; ...

2017-03-22

Collisionless shocks are common phenomena in space and astrophysical systems, and in many cases, the shocks can be modeled as the result of the expansion of a magnetic piston though a magnetized ambient plasma. Only recently, however, have laser facilities and diagnostic capabilities evolved sufficiently to allow the detailed study in the laboratory of the microphysics of piston-driven shocks. We review experiments on collisionless shocks driven by a laser-produced magnetic piston undertaken with the Phoenix laser laboratory and the Large Plasma Device at the University of California, Los Angeles. The experiments span a large parameter space in laser energy, backgroundmore » magnetic field, and ambient plasma properties that allow us to probe the physics of piston-ambient energy coupling, the launching of magnetosonic solitons, and the formation of subcritical shocks. Here, the results indicate that piston-driven magnetized collisionless shocks in the laboratory can be characterized with a small set of dimensionless formation parameters that place the formation process in an organized and predictive framework.« less

The gross anatomy laboratory: a novel venue for critical thinking and interdisciplinary teaching in dental education.

PubMed

Rowland, Kevin C; Joy, Anita

2015-03-01

Reports on the status of dental education have concluded that there is a need for various types of curricular reform, making recommendations that include better integration of basic, behavioral, and clinical sciences, increased case-based teaching, emphasis on student-driven learning, and creation of lifelong learners. Dental schools faced with decreasing contact hours, increasing teaching material, and technological advancements have experimented with alternate curricular strategies. At Southern Illinois University School of Dental Medicine, curricular changes have begun with a series of integrated biomedical sciences courses. During the process of planning and implementing the integrated courses, a novel venue-the gross anatomy laboratory-was used to introduce all Year 1 students to critical thinking, self-directed learning, and the scientific method. The venture included student-driven documentation of anatomical variations encountered in the laboratory using robust scientific methods, thorough literature review, and subsequent presentation of findings in peer review settings. Students responded positively, with over 75% agreeing the experience intellectually challenged them. This article describes the process of re-envisioning the gross anatomy laboratory as an effective venue for small group-based, student-driven projects that focus on key pedagogical concepts to encourage the development of lifelong learners.

Starship Sails Propelled by Cost-Optimized Directed Energy

NASA Astrophysics Data System (ADS)

Benford, J.

Microwave and laser-propelled sails are a new class of spacecraft using photon acceleration. It is the only method of interstellar flight that has no physics issues. Laboratory demonstrations of basic features of beam-driven propulsion, flight, stability (`beam-riding'), and induced spin, have been completed in the last decade, primarily in the microwave. It offers much lower cost probes after a substantial investment in the launcher. Engineering issues are being addressed by other applications: fusion (microwave, millimeter and laser sources) and astronomy (large aperture antennas). There are many candidate sail materials: carbon nanotubes and microtrusses, beryllium, graphene, etc. For acceleration of a sail, what is the cost-optimum high power system? Here the cost is used to constrain design parameters to estimate system power, aperture and elements of capital and operating cost. From general relations for cost-optimal transmitter aperture and power, system cost scales with kinetic energy and inversely with sail diameter and frequency. So optimal sails will be larger, lower in mass and driven by higher frequency beams. Estimated costs include economies of scale. We present several starship point concepts. Systems based on microwave, millimeter wave and laser technologies are of equal cost at today's costs. The frequency advantage of lasers is cancelled by the high cost of both the laser and the radiating optic. Cost of interstellar sailships is very high, driven by current costs for radiation source, antennas and especially electrical power. The high speeds necessary for fast interstellar missions make the operating cost exceed the capital cost. Such sailcraft will not be flown until the cost of electrical power in space is reduced orders of magnitude below current levels.

Fruit fly scale robots can hover longer with flapping wings than with spinning wings.

PubMed

Hawkes, Elliot W; Lentink, David

2016-10-01

Hovering flies generate exceptionally high lift, because their wings generate a stable leading edge vortex. Micro flying robots with a similar wing design can generate similar high lift by either flapping or spinning their wings. While it requires less power to spin a wing, the overall efficiency depends also on the actuator system driving the wing. Here, we present the first holistic analysis to calculate how long a fly-inspired micro robot can hover with flapping versus spinning wings across scales. We integrate aerodynamic data with data-driven scaling laws for actuator, electronics and mechanism performance from fruit fly to hummingbird scales. Our analysis finds that spinning wings driven by rotary actuators are superior for robots with wingspans similar to hummingbirds, yet flapping wings driven by oscillatory actuators are superior at fruit fly scale. This crossover is driven by the reduction in performance of rotary compared with oscillatory actuators at smaller scale. Our calculations emphasize that a systems-level analysis is essential for trading-off flapping versus spinning wings for micro flying robots. © 2016 The Author(s).

Fruit fly scale robots can hover longer with flapping wings than with spinning wings

PubMed Central

Lentink, David

2016-01-01

Hovering flies generate exceptionally high lift, because their wings generate a stable leading edge vortex. Micro flying robots with a similar wing design can generate similar high lift by either flapping or spinning their wings. While it requires less power to spin a wing, the overall efficiency depends also on the actuator system driving the wing. Here, we present the first holistic analysis to calculate how long a fly-inspired micro robot can hover with flapping versus spinning wings across scales. We integrate aerodynamic data with data-driven scaling laws for actuator, electronics and mechanism performance from fruit fly to hummingbird scales. Our analysis finds that spinning wings driven by rotary actuators are superior for robots with wingspans similar to hummingbirds, yet flapping wings driven by oscillatory actuators are superior at fruit fly scale. This crossover is driven by the reduction in performance of rotary compared with oscillatory actuators at smaller scale. Our calculations emphasize that a systems-level analysis is essential for trading-off flapping versus spinning wings for micro flying robots. PMID:27707903

A new phosphate-selective sorbent for the Rem Nut process. Laboratory investigation and field experience at a medium size wastewater treatment plant.

PubMed

Petruzzelli, D; De Florio, L; Dell'Erba, A; Liberti, L; Notarnicola, M; Sengupta, A K

2003-01-01

P-control technologies for municipal wastewater are essentially based on "destructive" methods, that lead to formation of concentrated solid-phases (sludge), usually disposed-off in controlled landfills. Ion exchange, as a "non-destructive" technology, allows for selective removal and simultaneous recovery of pollutants, which can be recycled to the same and/or related productive lines. In this context, the REM NUT process removes nutrient species (HPO4 = , NH4+, K+) present in biologically oxidised municipal effluents and recovers them in the form of struvites (MgNH4PO4; MgKPO4), premium quality slow release fertilisers. The main limitation to the extensive application of this ion exchange based process is the non-availability of selective exchangers for specific removal of nutrient species. This paper illustrates laboratory investigation and pilot scale development of a so-called "P-driven" modified REM NUT scheme based on a new phosphate-selective sorbent developed at Lehigh University, PA, USA.

High resolution monitoring of strain fields in concrete during hydraulic fracturing processes.

PubMed

Chen, Rongzhang; Zaghloul, Mohamed A S; Yan, Aidong; Li, Shuo; Lu, Guanyi; Ames, Brandon C; Zolfaghari, Navid; Bunger, Andrew P; Li, Ming-Jun; Chen, Kevin P

2016-02-22

We present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this paper provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.

Parallel collisionless shocks forming in simulations of the LAPD experiment

NASA Astrophysics Data System (ADS)

Weidl, Martin S.; Jenko, Frank; Niemann, Chris; Winske, Dan

2016-10-01

Research on parallel collisionless shocks, most prominently occurring in the Earth's bow shock region, has so far been limited to satellite measurements and simulations. However, the formation of collisionless shocks depends on a wide range of parameters and scales, which can be accessed more easily in a laboratory experiment. Using a kJ-class laser, an ongoing experimental campaign at the Large Plasma Device (LAPD) at UCLA is expected to produce the first laboratory measurements of the formation of a parallel collisionless shock. We present hybrid kinetic/MHD simulations that show how beam instabilities in the background plasma can be driven by ablating carbon ions from a target, causing non-linear density oscillations which develop into a propagating shock front. The free-streaming carbon ions can excite both the resonant right-hand instability and the non-resonant firehose mode. We analyze their respective roles and discuss optimizing their growth rates to speed up the process of shock formation.

High resolution monitoring of strain fields in concrete during hydraulic fracturing processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Rongzhang; Zaghloul, Mohamed A. S.; Yan, Aidong

Here, we present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this papermore » provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.« less

High resolution monitoring of strain fields in concrete during hydraulic fracturing processes

DOE PAGES

Chen, Rongzhang; Zaghloul, Mohamed A. S.; Yan, Aidong; ...

2016-02-17

Here, we present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this papermore » provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.« less

Numerical modeling of laser-driven experiments aiming to demonstrate magnetic field amplification via turbulent dynamo

DOE PAGES

Tzeferacos, Petros; Rigby, A.; Bott, A.; ...

2017-03-22

The universe is permeated by magnetic fields, with strengths ranging from a femtogauss in the voids between the filaments of galaxy clusters to several teragauss in black holes and neutron stars. The standard model behind cosmological magnetic fields is the nonlinear amplification of seed fields via turbulent dynamo to the values observed. We have conceived experiments that aim to demonstrate and study the turbulent dynamo mechanism in the laboratory. Here, we describe the design of these experiments through simulation campaigns using FLASH, a highly capable radiation magnetohydrodynamics code that we have developed, and large-scale three-dimensional simulations on the Mira supercomputermore » at the Argonne National Laboratory. The simulation results indicate that the experimental platform may be capable of reaching a turbulent plasma state and determining the dynamo amplification. As a result, we validate and compare our numerical results with a small subset of experimental data using synthetic diagnostics.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swapan Chattopadhyay

Hurricane Isabel was at category five--the most violent on the Saffir-Simpson scale of hurricane strength--when it began threatening the central Atlantic seaboard of the US. Over the course of several days, precautions against the extreme weather conditions were taken across the Jefferson Lab site in south-east Virginia. On 18 September 2003, when Isabel struck North Carolina's Outer Banks and moved northward, directly across the region around the laboratory, the storm was still quite destructive, albeit considerably reduced in strength. The flood surge and trees felled by wind substantially damaged or even devastated buildings and homes, including many belonging to Jeffersonmore » Lab staff members. For the laboratory itself, Isabel delivered an unplanned and severe challenge in another form: a power outage that lasted nearly three-and-a-half days, and which severely tested the robustness of Jefferson Lab's two superconducting machines, the Continuous Electron Beam Accelerator Facility (CEBAF) and the superconducting radiofrequency ''driver'' accelerator of the laboratory's free-electron laser. Robustness matters greatly for science at a time when microwave superconducting linear accelerators (linacs) are not only being considered, but in some cases already being built for projects such as neutron sources, rare-isotope accelerators, innovative light sources and TeV-scale electron-positron linear colliders. Hurricane Isabel interrupted a several-week-long maintenance shutdown of CEBAF, which serves nuclear and particle physics and represents the world's pioneering large-scale implementation of superconducting radiofrequency (SRF) technology. The racetrack-shaped machine is actually a pair of 500-600 MeV SRF linacs interconnected by recirculation arc beamlines. CEBAF delivers simultaneous beams at up to 6 GeV to three experimental halls. An imminent upgrade will double the energy to 12 GeV and add an extra hall for ''quark confinement'' studies. On a smaller scale, Jefferson Lab's original kilowatt-scale infrared free-electron laser (FEL) is ''driven'' by a high-current cousin of CEBAF, a 70 MeV SRF linac with a high-current injector. The FEL serves multidisciplinary science and technology as the world's highest-average-power source of tunable coherent infrared light. An upgrade to 10 kW is in commissioning--as it was when Isabel began threatening.« less

Novel approaches to microbial enhancement of oil recovery.

PubMed

Kryachko, Yuriy

2018-01-20

Microbially enhanced oil recovery (MEOR) was shown to be feasible in a number of laboratory experiments and field trials. However, it has not been widely used in the oil industry because necessary conditions cannot always be easily established in an oil reservoir. Novel approaches to MEOR, which are based on newly discovered biosurfactant-mediated MEOR-mechanisms, are discussed in this review. Particularly, the possibility of combining MEOR with chemical enhancement of oil recovery in heterogeneous oil reservoirs, which involves rock surface wettability shifts and emulsion inversions, is discussed. In wider (centimeter/millimeter-scale) rock pores, the activity of (bio)surfactants and microbial cells attached to oil may allow releasing trapped oil blobs through oil-in-water emulsification. After no more oil can be emulsified, the addition of alkali or surfactants, which turn rock surface oil-wet, may help release oil droplets trapped in narrow (micrometer-scale) pores through coalescence of the droplets and water-in-oil emulsification. Experiments demonstrating the possibility of (bio)surfactant-mediated enhancement of immiscible gas-driven oil recovery are also reviewed. Interestingly, very low (bio)surfactant concentrations were shown to be needed for enhancement of immiscible gas-driven oil recovery. Some possible side effects of MEOR, such as unintended bioplugging and microbially influenced corrosion (MIC), are discussed as well. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Unraveling the physics of magnetic reconnection: the interaction of laboratory and space observations with models

NASA Astrophysics Data System (ADS)

Drake, James

2017-10-01

Reconnection leads to impulsive conversion of magnetic energy into high-speed flows, plasma heating and the production of energetic particles. A major challenge has been to account for the enormous range of spatial scales in systems undergoing reconnection. Progress on the topic has been facilitated by the observations in space and the laboratory with models bridging the divide. Understanding the mechanisms for fast reconnection is a historical example. However, in this talk I will focus on reconnection in asymmetric systems - those with large ambient gradients in the pressure or density. The interest in the topic has been driven by efforts to understand when and where reconnection takes place in the laboratory (tokamaks) and in space (planetary magnetospheres and the solar wind). Ideas on reconnection suppression due to diamagnetic drifts have produced a unified picture of the conditions required for reconnection onset over a wide range of environments. Observations from the MMS mission have provided an extraordinary window into reconnection at the Earth's magnetopause, including the mechanisms for magnetic energy dissipation and the role of turbulence. Finally, the prospects for establishing the mechanisms for energetic particle production will be addressed.

Considerations for Explosively Driven Conical Shock Tube Design: Computations and Experiments

DTIC Science & Technology

2017-02-16

ARL-TR-7953 ● FEB 2017 US Army Research Laboratory Considerations for Explosively Driven Conical Shock Tube Design : Computations...The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized...Considerations for Explosively Driven Conical Shock Tube Designs : Computations and Experiments by Joel B Stewart Weapons and Materials Research Directorate

Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, C. K.; Tzeferacos, P.; Lamb, D.

X-ray images from the Chandra X-ray Observatory show that the South-East jet in the Crab nebula changes direction every few years. This remarkable phenomenon is also observed in jets associated with pulsar wind nebulae and other astrophysical objects, and therefore is a fundamental feature of astrophysical jet evolution that needs to be understood. Theoretical modeling and numerical simulations have suggested that this phenomenon may be a consequence of magnetic fields (B) and current-driven magnetohydrodynamic (MHD) instabilities taking place in the jet, but until now there has been no verification of this process in a controlled laboratory environment. Here we reportmore » the first such experiments, using scaled laboratory plasma jets generated by high-power lasers to model the Crab jet and monoenergetic-proton radiography to provide direct visualization and measurement of magnetic fields and their behavior. The toroidal magnetic field embedded in the supersonic jet triggered plasma instabilities and resulted in considerable deflections throughout the jet propagation, mimicking the kinks in the Crab jet. We also demonstrated that these kinks are stabilized by high jet velocity, consistent with the observation that instabilities alter the jet orientation but do not disrupt the overall jet structure. We successfully modeled these laboratory experiments with a validated three-dimensional (3D) numerical simulation, which in conjunction with the experiments provide compelling evidence that we have an accurate model of the most important physics of magnetic fields and MHD instabilities in the observed, kinked jet in the Crab nebula. The experiments initiate a novel approach in the laboratory for visualizing fields and instabilities associated with jets observed in various astrophysical objects, ranging from stellar to extragalactic systems. We expect that future work along this line will have important impact on the study and understanding of such fundamental astrophysical phenomena.« less

Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet

DOE PAGES

Li, C. K.; Tzeferacos, P.; Lamb, D.; ...

2016-10-07

X-ray images from the Chandra X-ray Observatory show that the South-East jet in the Crab nebula changes direction every few years. This remarkable phenomenon is also observed in jets associated with pulsar wind nebulae and other astrophysical objects, and therefore is a fundamental feature of astrophysical jet evolution that needs to be understood. Theoretical modeling and numerical simulations have suggested that this phenomenon may be a consequence of magnetic fields (B) and current-driven magnetohydrodynamic (MHD) instabilities taking place in the jet, but until now there has been no verification of this process in a controlled laboratory environment. Here we reportmore » the first such experiments, using scaled laboratory plasma jets generated by high-power lasers to model the Crab jet and monoenergetic-proton radiography to provide direct visualization and measurement of magnetic fields and their behavior. The toroidal magnetic field embedded in the supersonic jet triggered plasma instabilities and resulted in considerable deflections throughout the jet propagation, mimicking the kinks in the Crab jet. We also demonstrated that these kinks are stabilized by high jet velocity, consistent with the observation that instabilities alter the jet orientation but do not disrupt the overall jet structure. We successfully modeled these laboratory experiments with a validated three-dimensional (3D) numerical simulation, which in conjunction with the experiments provide compelling evidence that we have an accurate model of the most important physics of magnetic fields and MHD instabilities in the observed, kinked jet in the Crab nebula. The experiments initiate a novel approach in the laboratory for visualizing fields and instabilities associated with jets observed in various astrophysical objects, ranging from stellar to extragalactic systems. We expect that future work along this line will have important impact on the study and understanding of such fundamental astrophysical phenomena.« less

Development of a Scale to Measure Learners' Perceived Preferences and Benefits of Data-Driven Learning

ERIC Educational Resources Information Center

Mizumoto, Atsushi; Chujo, Kiyomi; Yokota, Kenji

2016-01-01

In spite of researchers' and practitioners' increasing attention to data-driven learning (DDL) and increasing numbers of DDL studies, a multi-item scale to measure learners' attitude toward DDL has not been developed thus far. In the present study, we developed and validated a psychometric scale to measure learners' perceived preferences and…

Control of Infectious Diseases in the Era of European Clinical Microbiology Laboratory Consolidation: New Challenges and Opportunities for the Patient and for Public Health Surveillance

PubMed Central

Vandenberg, Olivier; Kozlakidis, Zisis; Schrenzel, Jacques; Struelens, Marc Jean; Breuer, Judith

2018-01-01

Many new innovative diagnostic approaches have been made available during the last 10 years with major impact on patient care and public health surveillance. In parallel, to enhance the cost-effectiveness of the clinical microbiology laboratories (CMLs), European laboratory professionals have streamlined their organization leading to amalgamation of activities and restructuring of their professional relationships with clinicians and public health specialists. Through this consolidation process, an operational model has emerged that combines large centralized clinical laboratories performing most tests on one high-throughput analytical platform connected to several distal laboratories dealing locally with urgent analyses at near point of care. The centralization of diagnostic services over a large geographical region has given rise to the concept of regional-scale “microbiology laboratories network.” Although the volume-driven cost savings associated with such laboratory networks seem self-evident, the consequence(s) for the quality of patient care and infectious disease surveillance and control remain less obvious. In this article, we describe the range of opportunities that the changing landscape of CMLs in Europe can contribute toward improving the quality of patient care but also the early detection and enhanced surveillance of public health threats caused by infectious diseases. The success of this transformation of health services is reliant on the appropriate preparation in terms of staff, skills, and processes that would be inclusive of stakeholders. In addition, rigorous metrics are needed to set out more concrete laboratory service performance objectives and assess the expected benefits to society in terms of saving lives and preventing diseases. PMID:29457001

Particle Energization via Tearing Instability with Global Self-Organization Constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarff, John; Guo, Fan

The presentation reviews how tearing magnetic reconnection leads to powerful ion energization in reversed field pinch (RFP) plasmas. A mature MHD model for tearing instability has been developed that captures key nonlinear dynamics from the global to intermediate spatial scales. A turbulent cascade is also present that extends to at least the ion gyroradius scale, within which important particle energization mechanisms are anticipated. In summary, Ion heating and acceleration associated with magnetic reconnection from tearing instability is a powerful process in the RFP laboratory plasma (gyro-resonant and stochastic processes are likely candidates to support the observed rapid heating and othermore » features, reconnection-driven electron heating appears weaker or even absent, energetic tail formation for ions and electrons). Global self-organization strongly impacts particle energization (tearing interactions that span to core to edge, global magnetic flux change produces a larger electric field and runaway, correlations in electric and magnetic field fluctuations needed for dynamo feedback, impact of transport processes (which can be quite different for ions and electrons), inhomogeneity on the system scale, e.g., strong edge gradients).« less

Generation of scaled protogalactic seed magnetic fields in laser-produced shock waves.

PubMed

Gregori, G; Ravasio, A; Murphy, C D; Schaar, K; Baird, A; Bell, A R; Benuzzi-Mounaix, A; Bingham, R; Constantin, C; Drake, R P; Edwards, M; Everson, E T; Gregory, C D; Kuramitsu, Y; Lau, W; Mithen, J; Niemann, C; Park, H-S; Remington, B A; Reville, B; Robinson, A P L; Ryutov, D D; Sakawa, Y; Yang, S; Woolsey, N C; Koenig, M; Miniati, F

2012-01-25

The standard model for the origin of galactic magnetic fields is through the amplification of seed fields via dynamo or turbulent processes to the level consistent with present observations. Although other mechanisms may also operate, currents from misaligned pressure and temperature gradients (the Biermann battery process) inevitably accompany the formation of galaxies in the absence of a primordial field. Driven by geometrical asymmetries in shocks associated with the collapse of protogalactic structures, the Biermann battery is believed to generate tiny seed fields to a level of about 10(-21) gauss (refs 7, 8). With the advent of high-power laser systems in the past two decades, a new area of research has opened in which, using simple scaling relations, astrophysical environments can effectively be reproduced in the laboratory. Here we report the results of an experiment that produced seed magnetic fields by the Biermann battery effect. We show that these results can be scaled to the intergalactic medium, where turbulence, acting on timescales of around 700 million years, can amplify the seed fields sufficiently to affect galaxy evolution.

Two types of foreshock activities observed on meter-scale laboratory faults: Slow-slip-driven and cascade-up

NASA Astrophysics Data System (ADS)

Yamashita, F.; Fukuyama, E.; Xu, S.; Kawakata, H.; Mizoguchi, K.; Takizawa, S.

2017-12-01

We report two types of foreshock activities observed on meter-scale laboratory experiments: slow-slip-driven type and cascade-up type. We used two rectangular metagabbro blocks as experimental specimens, whose nominal contacting area was 1.5 m long and 0.1 m wide. To monitor stress changes and seismic activities on the fault, we installed dense arrays of 32 triaxial rosette strain gauges and 64 PZT seismic sensors along the fault. We repeatedly conducted experiments with the same pair of rock specimens, causing the evolution of damage on the fault. We focus on two experiments successively conducted under the same loading condition (normal stress of 6.7 MPa and loading rate of 0.01 mm/s) but different initial fault surface conditions; the first experiment preserved the gouge generated from the previous experiment while the second experiment started with all gouge removed. Note that the distribution of gouge was heterogeneous, because we did not make the gouge layer uniform. We observed many foreshocks in both experiments, but found that the b-value of foreshocks was smaller in the first experiment with pre-existing gouge (PEG). In the second experiment without PEG, we observed premonitory slow slip associated with nucleation process preceding most main events by the strain measurements. We also found that foreshocks were triggered by the slow slip at the end of the nucleation process. In the experiment with PEG, on the contrary, no clear premonitory slow slips were found. Instead, foreshock activity accelerated towards the main event, as confirmed by a decreasing b-value. Spatiotemporal distribution of foreshock hypocenters suggests that foreshocks migrated and cascaded up to the main event. We infer that heterogeneous gouge distribution caused stress-concentrated and unstable patches, which impeded stable slow slip but promoted foreshocks on the fault. Further, our results suggest that b-value is a useful parameter for characterizing these observations.

Three-Dimensional Smoothed Particle Hydrodynamics Modeling of Preferential Flow Dynamics at Fracture Intersections on a High-Performance Computing Platform

NASA Astrophysics Data System (ADS)

Kordilla, J.; Bresinsky, L. T.

2017-12-01

The physical mechanisms that govern preferential flow dynamics in unsaturated fractured rock formations are complex and not well understood. Fracture intersections may act as an integrator of unsaturated flow, leading to temporal delay, intermittent flow and partitioning dynamics. In this work, a three-dimensional Pairwise-Force Smoothed Particle Hydrodynamics (PF-SPH) model is being applied in order to simulate gravity-driven multiphase flow at synthetic fracture intersections. SPH, as a meshless Lagrangian method, is particularly suitable for modeling deformable interfaces, such as three-phase contact dynamics of droplets, rivulets and free-surface films. The static and dynamic contact angle can be recognized as the most important parameter of gravity-driven free-surface flow. In SPH, surface tension and adhesion naturally emerges from the implemented pairwise fluid-fluid (sff) and solid-fluid (ssf) interaction force. The model was calibrated to a contact angle of 65°, which corresponds to the wetting properties of water on Poly(methyl methacrylate). The accuracy of the SPH simulations were validated against an analytical solution of Poiseuille flow between two parallel plates and against laboratory experiments. Using the SPH model, the complex flow mode transitions from droplet to rivulet flow of an experimental study were reproduced. Additionally, laboratory dimensionless scaling experiments of water droplets were successfully replicated in SPH. Finally, SPH simulations were used to investigate the partitioning dynamics of single droplets into synthetic horizontal fractures with various apertures (Δdf = 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 mm) and offsets (Δdoff = -1.5, -1.0, -0.5, 0, 1.0, 2.0, 3.0 mm). Fluid masses were measured in the domains R1, R2 and R3. The perfect conditions of ideally smooth surfaces and the SPH inherent advantage of particle tracking allow the recognition of small scale partitioning mechanisms and its importance for bulk flow behavior.

On the formation of Friedlander waves in a compressed-gas-driven shock tube

PubMed Central

Tasissa, Abiy F.; Hautefeuille, Martin; Fitek, John H.; Radovitzky, Raúl A.

2016-01-01

Compressed-gas-driven shock tubes have become popular as a laboratory-scale replacement for field blast tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure thought to resemble a Friedlander wave, although this remains to be demonstrated theoretically. In this paper, we develop a semi-analytical model to predict the key characteristics of pseudo blast waves forming in a shock tube: location where the wave first forms, peak over-pressure, decay time and impulse. The approach is based on combining the solutions of the two different types of wave interactions that arise in the shock tube after the family of rarefaction waves in the Riemann solution interacts with the closed end of the tube. The results of the analytical model are verified against numerical simulations obtained with a finite volume method. The model furnishes a rational approach to relate shock tube parameters to desired blast wave characteristics, and thus constitutes a useful tool for the design of shock tubes for blast testing. PMID:27118888

Modeling Laser-Driven Laboratory Astrophysics Experiments Using the CRASH Code

NASA Astrophysics Data System (ADS)

Grosskopf, Michael; Keiter, P.; Kuranz, C. C.; Malamud, G.; Trantham, M.; Drake, R.

2013-06-01

Laser-driven, laboratory astrophysics experiments can provide important insight into the physical processes relevant to astrophysical systems. The radiation hydrodynamics code developed by the Center for Radiative Shock Hydrodynamics (CRASH) at the University of Michigan has been used to model experimental designs for high-energy-density laboratory astrophysics campaigns on OMEGA and other high-energy laser facilities. This code is an Eulerian, block-adaptive AMR hydrodynamics code with implicit multigroup radiation transport and electron heat conduction. The CRASH model has been used on many applications including: radiative shocks, Kelvin-Helmholtz and Rayleigh-Taylor experiments on the OMEGA laser; as well as laser-driven ablative plumes in experiments by the Astrophysical Collisionless Shocks Experiments with Lasers (ACSEL) collaboration. We report a series of results with the CRASH code in support of design work for upcoming high-energy-density physics experiments, as well as comparison between existing experimental data and simulation results. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52- 08NA28616, by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-FG52-09NA29548, and by the National Laser User Facility Program, grant number DE-NA0000850.

A study of flame spread in engineered cardboard fuelbeds: Part II: Scaling law approach

Treesearch

Brittany A. Adam; Nelson K. Akafuah; Mark Finney; Jason Forthofer; Kozo Saito

2013-01-01

In this second part of a two part exploration of dynamic behavior observed in wildland fires, time scales differentiating convective and radiative heat transfer is further explored. Scaling laws for the two different types of heat transfer considered: Radiation-driven fire spread, and convection-driven fire spread, which can both occur during wildland fires. A new...

Field Epidemiology and Laboratory Training Programs in West Africa as a model for sustainable partnerships in animal and human health.

PubMed

Becker, Karen M; Ohuabunwo, Chima; Ndjakani, Yassa; Nguku, Patrick; Nsubuga, Peter; Mukanga, David; Wurapa, Frederick

2012-09-01

The concept of animal and human health experts working together toward a healthier world has been endorsed, but challenges remain in identifying concrete actions to move this one health concept from vision to action. In 2008, as a result of avian influenza outbreaks in West Africa, international donor support led to a unique opportunity to invest in Field Epidemiology and Laboratory Training Programs (FELTPs) in the region that engaged the animal and human health sectors to strengthen the capacity for prevention and control of zoonotic diseases. The FELTPs mixed 25% to 35% classroom and 65% to 75% field-based training and service for cohorts of physicians, veterinarians, and laboratory scientists. They typically consisted of a 2-year course leading to a master's degree in field epidemiology and public health laboratory management for midlevel public health leaders and competency-based short courses for frontline public health surveillance workers. Trainees and graduates work in multidisciplinary teams to conduct surveillance, outbreak investigations, and epidemiological studies for disease control locally and across borders. Critical outcomes of these programs include development of a cadre of public health leaders with core skills in integrated disease surveillance, outbreak investigation, vaccination campaigns, laboratory diagnostic testing, and epidemiological studies that address priority public health problems. A key challenge exists in identifying ways to successfully scale up and transform this innovative donor-driven program into a sustainable multisectoral one health workforce capacity development model.

Design and Construction of a Shock Tube Experiment for Multiphase Instability Experiments

NASA Astrophysics Data System (ADS)

Middlebrooks, John; Black, Wolfgang; Avgoustopoulos, Constantine; Allen, Roy; Kathakapa, Raj; Guo, Qiwen; McFarland, Jacob

2016-11-01

Hydrodynamic instabilities are important phenomena that have a wide range of practical applications in engineering and physics. One such instability, the shock driven multiphase instability (SDMI), arises when a shockwave accelerates an interface between two particle-gas mixtures with differing multiphase properties. The SDMI is present in high energy explosives, scramjets, and supernovae. A practical way of studying shock wave driven instabilities is through experimentation in a shock tube laboratory. This poster presentation will cover the design and data acquisition process of the University of Missouri's Fluid Mixing Shock Tube Laboratory. In the shock tube, a pressure generated shockwave is passed through a multiphase interface, creating the SDMI instability. This can be photographed for observation using high speed cameras, lasers, and advance imaging techniques. Important experimental parameters such as internal pressure and temperature, and mass flow rates of gases can be set and recorded by remotely controlled devices. The experimental facility provides the University of Missouri's Fluid Mixing Shock Tube Laboratory with the ability to validate simulated experiments and to conduct further inquiry into the field of shock driven multiphase hydrodynamic instabilities. Advisor.

Analyzing the dynamic response of rotating blades in small-scale wind turbines

NASA Astrophysics Data System (ADS)

Hsiung, Wan-Ying; Huang, Yu-Ting; Loh, Chin-Hsiung; Loh, Kenneth J.; Kamisky, Robert J.; Nip, Danny; van Dam, Cornelis

2014-03-01

The objective of this study was to validate modal analysis, system identification and damage detection of small-scale rotating wind turbine blades in the laboratory and in the field. Here, wind turbine blades were instrumented with accelerometers and strain gages, and data acquisition was achieved using a prototype wireless sensing system. In the first portion of this study conducted in the laboratory, sensors were installed onto metallic structural elements that were fabricated to be representative of an actual wind blade. In order to control the excitation (rotation of the wind blade), a motor was used to spin the blades at controlled angular velocities. The wind turbine was installed on a shaking table for testing under rotation of turbine blades. Data measured by the sensors were recorded while the blade was operated at different speeds. On the other hand, the second part of this study utilized a small-scale wind turbine system mounted on the rooftop of a building. The main difference, as compared to the lab tests, was that the field tests relied on actual wind excitations (as opposed to a controlled motor). The raw data from both tests were analyzed using signal processing and system identification techniques for deriving the model response of the blades. The multivariate singular spectrum analysis (MSSA) and covariance-driven stochastic subspace identification method (SSI-COV) were used to identify the dynamic characteristics of the system. Damage of one turbine blade (loose bolts connection) in the lab test was also conducted. The extracted modal properties for both undamaged and damage cases under different ambient or forced excitations (earthquake loading) were compared. These tests confirmed that dynamic characterization of rotating wind turbines was feasible, and the results will guide future monitoring studies planned for larger-scale systems.

Argument-Driven Inquiry

ERIC Educational Resources Information Center

Sampson, Victor; Grooms, Jonathon; Walker, Joi

2009-01-01

Argument-Driven Inquiry (ADI) is an instructional model that enables science teachers to transform a traditional laboratory activity into a short integrated instructional unit. To illustrate how the ADI instructional model works, this article describes an ADI lesson developed for a 10th-grade chemistry class. This example lesson was designed to…

Architecture of a Message-Driven Processor,

DTIC Science & Technology

1987-11-01

Jon Kaplan, Paul Song, Brian Totty, and Scott Wills Artifcial Intelligence Laboratory -4 Laboratory for Computer Science Massachusetts Institute of...Information Dally, Chao, Chien, Hassoun, Horwat, Kaplan, Song, Totty & Wills: Artificial Intelligence i Laboratory and Laboratory for Computer Science, MIT...applied to a problem if we could are 36 bits long (32 data bits + 4 tag bits) and are used to hold efficiently run programs with a granularity of 5s

An Inquiry-Based Contextual Approach as the Primary Mode of Learning Science with Microcomputer-Based Laboratory Technology

ERIC Educational Resources Information Center

Espinoza, Fernando; Quarless, Duncan

2010-01-01

Science instruction can be designed to be laboratory-data driven. We report on an investigation of the use of thematic inquiry-based tasks with active incorporation of mathematics, science, and microcomputer-based laboratory technology in standards-correlated activities that enhanced learning experiences. Activities involved students in two major…

Lakeside: Merging Urban Design with Scientific Analysis

ScienceCinema

Guzowski, Leah; Catlett, Charlie; Woodbury, Ed

2018-01-16

Researchers at the U.S. Department of Energy's Argonne National Laboratory and the University of Chicago are developing tools that merge urban design with scientific analysis to improve the decision-making process associated with large-scale urban developments. One such tool, called LakeSim, has been prototyped with an initial focus on consumer-driven energy and transportation demand, through a partnership with the Chicago-based architectural and engineering design firm Skidmore, Owings & Merrill, Clean Energy Trust and developer McCaffery Interests. LakeSim began with the need to answer practical questions about urban design and planning, requiring a better understanding about the long-term impact of design decisions on energy and transportation demand for a 600-acre development project on Chicago's South Side - the Chicago Lakeside Development project.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Ping

Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (%3C50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberrationmore » - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the "glue" that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase - field modeling tools that can be used for future materials research at Sandia. Acknowledgeme nts This work was supported by the Laboratory Directed Research and Development (LDRD) program of Sandia National Laboratories. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidia ry of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000.« less

On the imprint of surfactant-driven stabilization of laboratory breaking wave foam with comparison to oceanic whitecaps

NASA Astrophysics Data System (ADS)

Callaghan, A. H.; Deane, G. B.; Stokes, M. D.

2017-08-01

Surfactants are ubiquitous in the global oceans: they help form the materially-distinct sea surface microlayer (SML) across which global ocean-atmosphere exchanges take place, and they reside on the surfaces of bubbles and whitecap foam cells prolonging their lifetime thus altering ocean albedo. Despite their importance, the occurrence, spatial distribution, and composition of surfactants within the upper ocean and the SML remains under-characterized during conditions of vigorous wave breaking when in-situ sampling methods are difficult to implement. Additionally, no quantitative framework exists to evaluate the importance of surfactant activity on ocean whitecap foam coverage estimates. Here we use individual laboratory breaking waves generated in filtered seawater and seawater with added soluble surfactant to identify the imprint of surfactant activity in whitecap foam evolution. The data show a distinct surfactant imprint in the decay phase of foam evolution. The area-time-integral of foam evolution is used to develop a time-varying stabilization function, ϕ>(t>) and a stabilization factor, Θ, which can be used to identify and quantify the extent of this surfactant imprint for individual breaking waves. The approach is then applied to wind-driven oceanic whitecaps, and the laboratory and ocean Θ distributions overlap. It is proposed that whitecap foam evolution may be used to determine the occurrence and extent of oceanic surfactant activity to complement traditional in-situ techniques and extend measurement capabilities to more severe sea states occurring at wind speeds in excess of about 10 m/s. The analysis procedure also provides a framework to assess surfactant-driven variability within and between whitecap coverage data sets.