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Sample records for dacs-sc dendreon buoyant

  1. Sipuleucel-T: APC 8015, APC-8015, prostate cancer vaccine--Dendreon.

    PubMed

    2006-01-01

    Sipuleucel-T [APC 8015, Provenge] is an autologous, dendritic cell-based vaccine under development with Dendreon Corporation for the treatment of androgen-independent and androgen-dependent prostate cancer. It was generated using the company's active immunotherapy platform to stimulate a patient's own immune system to specifically target and destroy cancer cells, while leaving healthy cells unharmed. This approach could provide patients with a meaningful survival benefit and an improved tolerability profile over existing anticancer therapies. Sipuleucel-T selectively targets the prostate-specific antigen (PSA) known as prostatic acid phosphatase (PAP) that is expressed in approximately 95% of prostate cancers. It is produced by ex vivo exposure of dendritic cell precursors to PA 2024, a recombinant fusion protein composed of the PAP target fused to granulocyte-macrophage colony-stimulating factor (GM-CSF) and incorporated into Dendreon's proprietary Antigen Delivery Cassette. Patients are typically administered three intravenous (IV)-infusions of the vaccine over a 1-month period as a complete course of therapy. It is undergoing late-stage clinical evaluation among patients with early and advanced prostate cancer. In November 2003, Kirin Brewery returned to Dendreon the full rights to Sipuleucel-T for Asia. In exchange, Dendreon licensed patent rights relating to the use of certain HLA-DR antibodies to Kirin for $US20 million. This amended agreement enables Dendreon to complete ongoing discussions for a worldwide marketing and sales partnership for Sipuleucel-T. Similarly, Kirin is able to develop its HLA-DR monoclonal antibodies free of potential infringement claims arising from Dendreon's patent rights to HLA-DR. The licensing agreement relates to patent rights owned by Dendreon relating to monoclonal antibodies against the HLA-DR antigen. In addition, Dendreon retains rights to develop and commercialise its two existing HLA-DR monoclonal antibodies, DN 1921 and

  2. Stacked Buoyant Payload Launcher

    DTIC Science & Technology

    2013-05-14

    reserved for undersea launched missiles. Underwater deployment of smaller payloads has been limited to ejection from torpedo tubes, the trash disposal...COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Stacked Buoyant Payload Launcher 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...1 of 11 STACKED BUOYANT PAYLOAD LAUNCHER STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and

  3. Hydrostatic Modeling of Buoyant Plumes

    NASA Astrophysics Data System (ADS)

    Stroman, A.; Dewar, W. K.; Wienders, N.; Deremble, B.

    2014-12-01

    The Deepwater Horizon oil spill in the Gulf of Mexico has led to increased interest in understanding point source convection dynamics. Most of the existing oil plume models use a Lagrangian based approach, which computes integral measures such as plume centerline trajectory and plume radius. However, this approach doesn't account for feedbacks of the buoyant plume on the ambient environment. Instead, we employ an Eulerian based approach to acquire a better understanding of the dynamics of buoyant plumes. We have performed a series of hydrostatic modeling simulations using the MITgcm. Our results show that there is a dynamical response caused by the presence of the buoyant plume, in that there is a modification of the background flow. We find that the buoyant plume becomes baroclinically unstable and sheds eddies at the neutral buoyancy layer. We also explore different scenarios to determine the effect of the buoyancy source and the temperature stratification on the evolution of buoyant plumes.

  4. Buoyant Norbury's vortex rings

    NASA Astrophysics Data System (ADS)

    Blyth, Mark; Rodriguez-Rodriguez, Javier; Salman, Hayder

    2014-11-01

    Norbury's vortices are a one-parameter family of axisymmetric vortex rings that are exact solutions to the Euler equations. Due to their relative simplicity, they are extensively used to model the behavior of real vortex rings found in experiments and in Nature. In this work, we extend the original formulation of the problem to include buoyancy effects for the case where the fluid that lies within the vortex has a different density to that of the ambient. In this modified formulation, buoyancy effects enter the problem through the baroclinic term of the vorticity equation. This permits an efficient numerical solution of the governing equation of motion in terms of a vortex contour method that tracks the evolution of the boundary of the vortex. Finally, we compare our numerical results with the theoretical analysis of the short-time evolution of a buoyant vortex. Funded by the Spanish Ministry of Economy and Competitiveness through grant DPI2011-28356-C03-02 and by the London Mathematical Society.

  5. Buoyant plume calculations

    SciTech Connect

    Penner, J.E.; Haselman, L.C.; Edwards, L.L.

    1985-01-01

    Smoke from raging fires produced in the aftermath of a major nuclear exchange has been predicted to cause large decreases in surface temperatures. However, the extent of the decrease and even the sign of the temperature change, depend on how the smoke is distributed with altitude. We present a model capable of evaluating the initial distribution of lofted smoke above a massive fire. Calculations are shown for a two-dimensional slab version of the model and a full three-dimensional version. The model has been evaluated by simulating smoke heights for the Hamburg firestorm of 1943 and a smaller scale oil fire which occurred in Long Beach in 1958. Our plume heights for these fires are compared to those predicted by the classical Morton-Taylor-Turner theory for weakly buoyant plumes. We consider the effect of the added buoyancy caused by condensation of water-laden ground level air being carried to high altitude with the convection column as well as the effects of background wind on the calculated smoke plume heights for several fire intensities. We find that the rise height of the plume depends on the assumed background atmospheric conditions as well as the fire intensity. Little smoke is injected into the stratosphere unless the fire is unusually intense, or atmospheric conditions are more unstable than we have assumed. For intense fires significant amounts of water vapor are condensed raising the possibility of early scavenging of smoke particles by precipitation. 26 references, 11 figures.

  6. Drag of buoyant vortex rings

    NASA Astrophysics Data System (ADS)

    Vasel-Be-Hagh, Ahmadreza; Carriveau, Rupp; Ting, David S.-K.; Turner, John Stewart

    2015-10-01

    Extending from the model proposed by Vasel-Be-Hagh et al. [J. Fluid Mech. 769, 522 (2015), 10.1017/jfm.2015.126], a perturbation analysis is performed to modify Turner's radius by taking into account the viscous effect. The modified radius includes two terms; the zeroth-order solution representing the effect of buoyancy, and the first-order perturbation correction describing the influence of viscosity. The zeroth-order solution is explicit Turner's radius; the first-order perturbation modification, however, includes the drag coefficient, which is unknown and of interest. Fitting the photographically measured radius into the modified equation yields the time history of the drag coefficient of the corresponding buoyant vortex ring. To give further clarification, the proposed model is applied to calculate the drag coefficient of a buoyant vortex ring at a Bond number of approximately 85; a similar procedure can be applied at other Bond numbers.

  7. Effects of buoyant forces on chaotic electroconvection

    NASA Astrophysics Data System (ADS)

    Karatay, Elif; Wessling, Matthias; Mani, Ali; Stanford University, Department of Mechanical Engineering Collaboration; RWTH Aachen University, Department of Chemical Engineering Collaboration

    2015-11-01

    The transport of ionic species is enhanced by induced electroconvection that arise due to electrokinetic instabilities stemming from coupling of hydrodynamics with ion transport and electrostatic forces. Recent research have shown the contribution of chaotic multi-scale structures beyond a threshold value of applied electric potential. However the buoyant forces have been neglected in the existing studies of chaotic electrokinetic flows where the density gradients of salt depletion can become gravitationally stable or unstable depending on the geometric orientation of electrokinetic systems. In this study we thoroughly examine the interplay of gravitational convection and chaotic induced electroconvection in both gravitationally stable and unstable configurations via direct numerical simulations of a model system consisting of a salt solution confined in between two cation selective membranes. Our results reveal that buoyant forces are not negligible when the Rayleigh number of the system exceeds a critical value Racr ~ 1000 . When the density gradient of salt depletion is gravitationally stable, the growth of the electrokinetic flow structures are saturated by buoyant forces. Whereas gravitationally unstable density gradient leads to buoyant flow structures. Supported by Netherlands Organization for Scientific Research, Rubicon Grant.

  8. EXPERIMENTS ON BUOYANT PLUME DISPERSION IN A LABORATORY CONVENTION TANK

    EPA Science Inventory

    Buoyant plume dispersion in the convective boundary layer (CBL) is investigated experimentally in a laboratory convection tank. The focus is on highly-buoyant plumes that loft near the CBL capping inversion and resist downward mixing. Highly- buoyant plumes are those with dimen...

  9. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Life floats and buoyant apparatus. 131.870 Section 131... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant...

  10. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Life floats and buoyant apparatus. 131.870 Section 131... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant...

  11. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Life floats and buoyant apparatus. 131.870 Section 131... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant...

  12. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant apparatus... 46 Shipping 4 2011-10-01 2011-10-01 false Life floats and buoyant apparatus. 131.870 Section...

  13. 46 CFR 131.870 - Life floats and buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats and buoyant apparatus. (a) The name of the vessel must be plainly marked or painted on each life float or buoyant apparatus... 46 Shipping 4 2010-10-01 2010-10-01 false Life floats and buoyant apparatus. 131.870 Section...

  14. BUOYANT ADVECTION OF GASES IN UNSATURATED SOIL

    PubMed Central

    Seely, Gregory E.; Falta, Ronald W.; Hunt, James R.

    2010-01-01

    In unsaturated soil, methane and volatile organic compounds can significantly alter the density of soil gas and induce buoyant gas flow. A series of laboratory experiments was conducted in a two-dimensional, homogeneous sand pack with gas permeabilities ranging from 110 to 3,000 darcy. Pure methane gas was injected horizontally into the sand and steady-state methane profiles were measured. Experimental results are in close agreement with a numerical model that represents the advective and diffusive components of methane transport. Comparison of simulations with and without gravitational acceleration permits identification of conditions where buoyancy dominates methane transport. Significant buoyant flow requires a Rayleigh number greater than 10 and an injected gas velocity sufficient to overcome dilution by molecular diffusion near the source. These criteria allow the extension of laboratory results to idealized field conditions for methane as well as denser-than-air vapors produced by volatilizing nonaqueous phase liquids trapped in unsaturated soil. PMID:20396624

  15. Analytical model for a vertical buoyant jet

    SciTech Connect

    Lee, D.W.

    1980-10-01

    An analytical model for a round and two-dimensional turbulent buoyant jet which is discharged vertically into a stagnant ambient is developed. The buoyant jet is considered to have three separate zone models which are matched to form a complete solution. The velocity field is determined for the entire jet and plume regions by the use of an eddy viscosity which varies along the axis of the jet. The centerline decay of buoyancy is determined throughout and the results are compared to existing numerical codes. The model is applied to the disposal of carbon dioxide enriched seawater. The results can be used to provide design information for minimizing or maximizing the dilution of a discharge by the receiving environment.

  16. The diffusion of turbulent buoyant jets

    NASA Astrophysics Data System (ADS)

    Gebhart, B.; Hilder, D. S.; Kelleher, M.

    It is pointed out that the cooling water discharge from a power plant into a large body of water, the thermally loaded condenser discharge from the condenser of a moving ship, and the high-temperature gas issuing from a stack or gas turbine exhaust are all buoyant momentum jets. The present study is concerned with a single, fully turbulent, circular buoyant jet, discharged into a surrounding ambient of the same fluid. The characteristics of circular discharges are examined, and a review of modeling schemes and experimental studies is conducted. Attention is given to properties and ambient stratification modeling, a general formulation, comparative calculations regarding the simplest entrainment models and later entrainment models, comparative calculations involving jets in unstratified flowing ambients, the effects of ambient stratifications, and dimensionless variables.

  17. Water exit dynamics of buoyant spheres

    NASA Astrophysics Data System (ADS)

    Truscott, Tadd T.; Epps, Brenden P.; Munns, Randy H.

    2016-11-01

    Buoyant spheres released below the free surface can rise well above the surface in a phenomenon known as pop-up. Contrary to intuition, increasing the release depth sometimes results in a lower pop-up height. We present the pop-up height of rising buoyant spheres over a range of release depths (1-12.5 diameters) and Reynolds numbers (4 ×104 to 6 ×105 ). While the dynamics of rising buoyant spheres and bubbles has been thoroughly investigated for Reynolds numbers below 104, pop-up in these larger-Reynolds-number regimes has not been studied. Yet the underwater motions of the sphere for the Reynolds numbers we study are the key to understanding the pop-up height. Two major regimes are apparent: vertical and oscillatory. The vertical regime exhibits a nearly vertical underwater trajectory and results in the largest pop-up heights. The oscillatory regime exhibits an underwater trajectory with periodic lateral motions and results in lower pop-up heights; this periodic lateral motion is modulated by unsteady vortex shedding in the wake of the sphere. Despite these complex fluid structure interactions, the experiments presented herein yield extremely repeatable results.

  18. Buoyant densities of phototrophic sulfur bacteria and cyanobacteria

    NASA Technical Reports Server (NTRS)

    Guerrero, R.

    1985-01-01

    The buoyant densities of bacterial cells are greatly influenced by the accumulation of intracellular reserve material. The buoyant density of phototrophic bacteria that are planktonic is of particular interest, since these organisms must remain in the photic zone of the water column for optimal growth. Separation of cells by their buoyant density may also be of use in separating and identifying organisms from a natural population. The bacteria used were obtained from pure cultures, enrichments, or samples taken directly from the environment.

  19. 46 CFR 160.010-6 - Capacity of buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for Merchant Vessels § 160.010... immersed or where facilities are provided for climbing on top of the apparatus. (2) Number of 300 mm (1 ft... 46 Shipping 6 2011-10-01 2011-10-01 false Capacity of buoyant apparatus. 160.010-6 Section...

  20. 46 CFR 160.010-3 - Inflatable buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for Merchant Vessels § 160.010... container accessible to the occupants, or otherwise secured to the apparatus. Duplicate equipment must be provided, for each side of a reversible inflatable buoyant apparatus, if the equipment is not...

  1. 46 CFR 160.010-3 - Inflatable buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for Merchant Vessels § 160.010... container accessible to the occupants, or otherwise secured to the apparatus. Duplicate equipment must be provided, for each side of a reversible inflatable buoyant apparatus, if the equipment is not...

  2. 46 CFR 160.010-6 - Capacity of buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for Merchant Vessels § 160.010... immersed or where facilities are provided for climbing on top of the apparatus. (2) Number of 300 mm (1 ft... 46 Shipping 6 2010-10-01 2010-10-01 false Capacity of buoyant apparatus. 160.010-6 Section...

  3. 46 CFR 160.010-4 - General requirements for buoyant apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Buoyant apparatus must not have any evident defects in workmanship. (m) Each metal part of a buoyant...). (o) When fibrous-glass-reinforced plastic is used in the construction of a buoyant apparatus,...

  4. 46 CFR 160.010-4 - General requirements for buoyant apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Buoyant apparatus must not have any evident defects in workmanship. (m) Each metal part of a buoyant...). (o) When fibrous-glass-reinforced plastic is used in the construction of a buoyant apparatus,...

  5. A turbulence model for buoyant flows based on vorticity generation.

    SciTech Connect

    Domino, Stefan Paul; Nicolette, Vernon F.; O'Hern, Timothy John; Tieszen, Sheldon R.; Black, Amalia Rebecca

    2005-10-01

    A turbulence model for buoyant flows has been developed in the context of a k-{var_epsilon} turbulence modeling approach. A production term is added to the turbulent kinetic energy equation based on dimensional reasoning using an appropriate time scale for buoyancy-induced turbulence taken from the vorticity conservation equation. The resulting turbulence model is calibrated against far field helium-air spread rate data, and validated with near source, strongly buoyant helium plume data sets. This model is more numerically stable and gives better predictions over a much broader range of mesh densities than the standard k-{var_epsilon} model for these strongly buoyant flows.

  6. Buoyant Currents West and East of Greenland

    NASA Astrophysics Data System (ADS)

    Aksenov, Y.; Bacon, S.; Nurser, G.; Coward, A.

    2014-12-01

    Low salinity buoyant polar waters exit the Arctic Ocean into the Nordic Seas and the North Atlantic, affecting deep convection in the Nordic and Labrador Seas with potential impacts on the meridional overturning circulation. The pathways of the polar water in Davis Strait, Fram Strait and then to the south are well documented by observations and model simulations. In contrast, measurements upstream of Fram Strait are too sparse to allow us to explain what causes the outflows to exit either west or east of Greenland or to attribute the variability in the Arctic outflows to atmospheric or oceanic mechanisms. Two high-resolution global ocean general circulation models (OGCM), NEMO-ORCA025, of ~12 km resolution, and NEMO-ORCA12, of ~4 km resolution, have been used to examine the dynamics and seasonal variability of the outflow west and east of Greenland. Montgomery potential analysis is used to investigate the dynamics of the currents in the area. The model results suggest wind as a driving mechanism for the seasonal variability of the ocean circulation in the area.

  7. Filtered Rayleigh Scattering Measurements in a Buoyant Flow Field

    DTIC Science & Technology

    2008-03-01

    John William Strutt , the third Baron of Rayleigh , or more commonly known as Lord Rayleigh , was the first to offer a correct explanation of the...FILTERED RAYLEIGH SCATTERING MEASUREMENTS IN A BUOYANT FLOW FIELD         THESIS       Steven Michael Meents, Captain, USAF...AFIT/GAE/ENY/08-M22 FILTERED RAYLEIGH SCATTERING MEASUREMENTS IN A BUOYANT FLOW FIELD THESIS Presented to the Faculty Department of Aeronautics

  8. A new framework for simulating forced homogeneous buoyant turbulent flows

    NASA Astrophysics Data System (ADS)

    Carroll, Phares L.; Blanquart, Guillaume

    2015-06-01

    This work proposes a new simulation methodology to study variable density turbulent buoyant flows. The mathematical framework, referred to as homogeneous buoyant turbulence, relies on a triply periodic domain and incorporates numerical forcing methods commonly used in simulation studies of homogeneous, isotropic flows. In order to separate the effects due to buoyancy from those due to large-scale gradients, the linear scalar forcing technique is used to maintain the scalar variance at a constant value. Two sources of kinetic energy production are considered in the momentum equation, namely shear via an isotropic forcing term and buoyancy via the gravity term. The simulation framework is designed such that the four dimensionless parameters of importance in buoyant mixing, namely the Reynolds, Richardson, Atwood, and Schmidt numbers, can be independently varied and controlled. The framework is used to interrogate fully non-buoyant, fully buoyant, and partially buoyant turbulent flows. The results show that the statistics of the scalar fields (mixture fraction and density) are not influenced by the energy production mechanism (shear vs. buoyancy). On the other hand, the velocity field exhibits anisotropy, namely a larger variance in the direction of gravity which is associated with a statistical dependence of the velocity component on the local fluid density.

  9. The case for accretion of the tectosphere by buoyant subduction

    SciTech Connect

    Abbott, D. )

    1991-04-01

    The term tectosphere, which formerly applied to all continental lithosphere, more recently is restricted to the seismically fast, cold (meaning that diamond is stable), and thick ({ge}200-400 km) continental lithosphere. This paper tests three hypotheses for the origin of the tectosphere. Continental collision cannot explain the low metamorphic grade of crust that predates the tectosphere. Halfspace cooling and buoyant underplating can both fit the diamond age data, although underplating by buoyant subduction is the favored model. Thermal models provide a further test. If halfspace cooling formed the tectosphere, diamonds from 150 km depth will be at least 200 m.y. younger than diamonds from 190 km. If buoyant subduction formed the tectosphere, diamonds from 150 km depth will be the same age or older than diamonds from 190 km.

  10. 46 CFR 160.010-3 - Inflatable buoyant apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... inflatable buoyant apparatus must comply with subpart 160.151, with the following exceptions: (1) Canopy...)). It does not need a canopy. (2) Capacity (IMO LSA Code, chapter IV/4.1.2.1). The carrying capacity...) One or more exterior canopy lamps meeting the requirements of 46 CFR 160.151-15(n) must be...

  11. 46 CFR 160.010-3 - Inflatable buoyant apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... water when the device is fully loaded, and must prevent water from flowing back onto the floor. (8) If... boarding ladder, if no ramps are installed), and ready for immediate use; (ii) Knives. Two buoyant safety... set of sealing clamps or plugs as described in § 160.151-21(y)(1); (ix) Pump or bellows. One pump...

  12. 46 CFR 160.010-3 - Inflatable buoyant apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... water when the device is fully loaded, and must prevent water from flowing back onto the floor. (8) If... boarding ladder, if no ramps are installed), and ready for immediate use; (ii) Knives. Two buoyant safety... set of sealing clamps or plugs as described in § 160.151-21(y)(1); (ix) Pump or bellows. One pump...

  13. Hands-On Experiences with Buoyant-Less Water

    ERIC Educational Resources Information Center

    Slisko, Josip; Planinsic, Gorazd

    2010-01-01

    The phenomenon of weightlessness is known to students thanks to videos of amazing things astronauts do in spaceships orbiting the Earth. In this article we propose two hands-on activities which give students opportunities to infer by themselves the absence of buoyant force in a gravity accelerated system. The system is a free-falling or vertically…

  14. Propagating buoyant mantle upwelling on the Reykjanes Ridge

    NASA Astrophysics Data System (ADS)

    Martinez, Fernando; Hey, Richard

    2017-01-01

    Crustal features of the Reykjanes Ridge have been attributed to mantle plume flow radiating outward from the Iceland hotspot. This model requires very rapid mantle upwelling and a "rheological boundary" at the solidus to deflect plume material laterally and prevent extreme melting above the plume stem. Here we propose an alternative explanation in which shallow buoyant mantle upwelling instabilities propagate along axis to form the crustal features of the ridge and flanks. As only the locus of buoyant upwelling propagates this mechanism removes the need for rapid mantle plume flow. Based on new geophysical mapping we show that a persistent sub-axial low viscosity channel supporting buoyant mantle upwelling can explain the current oblique geometry of the ridge as a reestablishment of its original configuration following an abrupt change in opening direction. This mechanism further explains the replacement of ridge-orthogonal crustal segmentation with V-shaped crustal ridges and troughs. Our findings indicate that crustal features of the Reykjanes Ridge and flanks are formed by shallow buoyant mantle instabilities, fundamentally like at other slow spreading ridges, and need not reflect deep mantle plume flow.

  15. 46 CFR 160.010-6 - Capacity of buoyant apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... must be the lowest number determined by the following methods: (1) Final buoyancy of the buoyant... 145 (divided by 32 if buoyancy is measured in pounds). The divisor must be changed to 180 (40 if buoyancy is measured in pounds) if the apparatus is designed so that persons supported are only...

  16. 46 CFR 160.010-6 - Capacity of buoyant apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... must be the lowest number determined by the following methods: (1) Final buoyancy of the buoyant... 145 (divided by 32 if buoyancy is measured in pounds). The divisor must be changed to 180 (40 if buoyancy is measured in pounds) if the apparatus is designed so that persons supported are only...

  17. 46 CFR 160.010-6 - Capacity of buoyant apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... must be the lowest number determined by the following methods: (1) Final buoyancy of the buoyant... 145 (divided by 32 if buoyancy is measured in pounds). The divisor must be changed to 180 (40 if buoyancy is measured in pounds) if the apparatus is designed so that persons supported are only...

  18. 46 CFR 108.697 - Buoyant work vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Buoyant work vests. 108.697 Section 108.697 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND...; and (2) Of the same or similar design and have the same method of operation as each other hybrid...

  19. 46 CFR 108.697 - Buoyant work vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Buoyant work vests. 108.697 Section 108.697 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND...; and (2) Of the same or similar design and have the same method of operation as each other hybrid...

  20. 46 CFR 117.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Stowage of life floats and buoyant apparatus. 117.137... EQUIPMENT AND ARRANGEMENTS Survival Craft Arrangements and Equipment § 117.137 Stowage of life floats and buoyant apparatus. (a) In addition to meeting § 117.130, each life float and buoyant apparatus must...

  1. 46 CFR 131.580 - Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST... Inspections § 131.580 Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be...

  2. 46 CFR 117.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Stowage of life floats and buoyant apparatus. 117.137... EQUIPMENT AND ARRANGEMENTS Survival Craft Arrangements and Equipment § 117.137 Stowage of life floats and buoyant apparatus. (a) In addition to meeting § 117.130, each life float and buoyant apparatus must...

  3. 46 CFR 131.580 - Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST... Inspections § 131.580 Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be...

  4. 46 CFR 117.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Stowage of life floats and buoyant apparatus. 117.137... EQUIPMENT AND ARRANGEMENTS Survival Craft Arrangements and Equipment § 117.137 Stowage of life floats and buoyant apparatus. (a) In addition to meeting § 117.130, each life float and buoyant apparatus must...

  5. 46 CFR 160.010-5 - Buoyant apparatus with plastic foam buoyancy.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Buoyant apparatus with plastic foam buoyancy. 160.010-5... Vessels § 160.010-5 Buoyant apparatus with plastic foam buoyancy. (a) Buoyant apparatus with plastic foam buoyancy must have a plastic foam body with an external protective covering. The body may be reinforced...

  6. 46 CFR 160.010-5 - Buoyant apparatus with plastic foam buoyancy.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Buoyant apparatus with plastic foam buoyancy. 160.010-5... Vessels § 160.010-5 Buoyant apparatus with plastic foam buoyancy. (a) Buoyant apparatus with plastic foam buoyancy must have a plastic foam body with an external protective covering. The body may be reinforced...

  7. 46 CFR 160.010-5 - Buoyant apparatus with plastic foam buoyancy.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Buoyant apparatus with plastic foam buoyancy. 160.010-5... Vessels § 160.010-5 Buoyant apparatus with plastic foam buoyancy. (a) Buoyant apparatus with plastic foam buoyancy must have a plastic foam body with an external protective covering. The body may be reinforced...

  8. 46 CFR 160.010-5 - Buoyant apparatus with plastic foam buoyancy.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Buoyant apparatus with plastic foam buoyancy. 160.010-5... Vessels § 160.010-5 Buoyant apparatus with plastic foam buoyancy. (a) Buoyant apparatus with plastic foam buoyancy must have a plastic foam body with an external protective covering. The body may be reinforced...

  9. 46 CFR 160.010-5 - Buoyant apparatus with plastic foam buoyancy.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Buoyant apparatus with plastic foam buoyancy. 160.010-5... Vessels § 160.010-5 Buoyant apparatus with plastic foam buoyancy. (a) Buoyant apparatus with plastic foam buoyancy must have a plastic foam body with an external protective covering. The body may be reinforced...

  10. Buoyant triacylglycerol-filled green algae and methods therefor

    SciTech Connect

    Goodenough, Ursula; Goodson, Carrie

    2015-04-14

    Cultures of Chlamydomonas are disclosed comprising greater than 340 mg/l triacylglycerols (TAG). The cultures can include buoyant Chlamydomonas. Methods of forming the cultures are also disclosed. In some embodiments, these methods comprise providing Chlamydomonas growing in log phase in a first culture medium comprising a nitrogen source and acetate, replacing the first culture medium with a second medium comprising acetate but no nitrogen source, and subsequently supplementing the second medium with additional acetate. In some embodiments, a culture can comprise at least 1,300 mg/l triacyglycerols. In some embodiments, cultures can be used to produce a biofuel such as biodiesel.

  11. A rapidly-banding component of animal DNA preparations that interferes with buoyant density studies

    PubMed Central

    Kurnit, David M.

    1974-01-01

    Rapidly-banding components of purified animal cell DNA's have been observed which have abnormal buoyant densities and show anomalous band profiles when centrifuged to equilibrium in cesium salts. These components interfere with the separation of animal DNA fractions and with the analysis of animal cell DNA's by buoyant density techniques. They can be detected by examining photographs of analytical buoyant-density ultracentrifugations before equilibrium has been reached. These rapidly-banding components are removed by phenol treatment. Images PMID:10793678

  12. Phytoplankton productivity in a turbid buoyant coastal plume

    NASA Astrophysics Data System (ADS)

    Schofield, Oscar; Moline, Mark; Cahill, Brownyn; Frazer, Thomas; Kahl, Alex; Oliver, Matthew; Reinfelder, John; Glenn, Scott; Chant, Robert

    2013-07-01

    The complex dynamics associated with coastal buoyant plumes make it difficult to document the interactions between light availability, phytoplankton carbon fixation, and biomass accumulation. Using real-time data, provided by satellites and high frequency radar, we adaptively sampled a low salinity parcel of water that was exported from the Hudson river estuary in April 2005. The water was characterized by high nutrients and high chlorophyll concentrations. The majority of the low salinity water was re-circulated within a nearshore surface feature for 5 days during which nitrate concentrations dropped 7-fold, the maximum quantum yield for photosynthesis dropped 10-fold, and primary productivity rates decreased 5-fold. Associated with the decline in nitrate was an increase in phytoplankton biomass. The phytoplankton combined with the Colored Dissolved Organic Matter (CDOM) and non-algal particles attenuated the light so the 1% light level ranged between 3 and 10m depending on the age of the plume water. As the plume was 10-15m thick, the majority of the phytoplankton were light-limited. Vertical mixing within the plume was high as indicated by the dispersion of injected of rhodamine dye. The mixing within the buoyant plume was more rapid than phytoplankton photoacclimation processes. Mixing rates within the plume was the critical factor determining overall productivity rates within the turbid plume.

  13. On the cooling of a buoyant boundary current

    NASA Astrophysics Data System (ADS)

    Ou, Hsien-Wang

    2005-06-01

    Through a steady-state reduced-gravity model, we examine the downstream evolution of a buoyant boundary current as it is subjected to surface cooling. It is found that the adverse pressure gradient associated with the diminishing buoyancy is countered by falling pressure head, so the overall strength of the current—as measured by the (transport-weighted) mean square velocity—remains unchanged. This constancy also applies to the cross-stream difference of the square velocity because of the vorticity constraint, which leads to the general deduction that the net current shear is enhanced regardless of its upstream sign. As a consequence, if the upstream flow contains near-shore and offshore branches that are comparable in strength, this parity would persist downstream; but if the near-shore branch is weaker to begin with, it may be stagnated by cooling, with the ensuing generation of anti-cyclonic eddies. On account of the geostrophic balance, the buoyant layer narrows as the square root of the buoyancy—the same rate as the falling pressure head, but more rapid than that of the local deformation radius. Some of the model predictions are compared with observations from the Tsushima Current in the Japan/East Sea.

  14. Turbulence Statistics of a Buoyant Jet in a Stratified Environment

    NASA Astrophysics Data System (ADS)

    McCleney, Amy Brooke

    Using non-intrusive optical diagnostics, turbulence statistics for a round, incompressible, buoyant, and vertical jet discharging freely into a stably linear stratified environment is studied and compared to a reference case of a neutrally buoyant jet in a uniform environment. This is part of a validation campaign for computational fluid dynamics (CFD). Buoyancy forces are known to significantly affect the jet evolution in a stratified environment. Despite their ubiquity in numerous natural and man-made flows, available data in these jets are limited, which constrain our understanding of the underlying physical processes. In particular, there is a dearth of velocity field data, which makes it challenging to validate numerical codes, currently used for modeling these important flows. Herein, jet near- and far-field behaviors are obtained with a combination of planar laser induced fluorescence (PLIF) and multi-scale time-resolved particle image velocimetry (TR-PIV) for Reynolds number up to 20,000. Deploying non-intrusive optical diagnostics in a variable density environment is challenging in liquids. The refractive index is strongly affected by the density, which introduces optical aberrations and occlusions that prevent the resolution of the flow. One solution consists of using index matched fluids with different densities. Here a pair of water solutions - isopropanol and NaCl - are identified that satisfy these requirements. In fact, they provide a density difference up to 5%, which is the largest reported for such fluid pairs. Additionally, by design, the kinematic viscosities of the solutions are identical. This greatly simplifies the analysis and subsequent simulations of the data. The spectral and temperature dependence of the solutions are fully characterized. In the near-field, shear layer roll-up is analyzed and characterized as a function of initial velocity profile. In the far-field, turbulence statistics are reported for two different scales, one

  15. 46 CFR 131.580 - Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST..., and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be serviced... maintenance of inflatable rescue boats must follow the manufacturers' instructions. Each repair, except...

  16. 46 CFR 131.580 - Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST..., and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be serviced... maintenance of inflatable rescue boats must follow the manufacturers' instructions. Each repair, except...

  17. 46 CFR 131.580 - Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST..., and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be serviced... maintenance of inflatable rescue boats must follow the manufacturers' instructions. Each repair, except...

  18. 46 CFR 160.010-4 - General requirements for buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false General requirements for buoyant apparatus. 160.010-4 Section 160.010-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for...

  19. 46 CFR 180.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Stowage of life floats and buoyant apparatus. 180.137... (UNDER 100 GROSS TONS) LIFESAVING EQUIPMENT AND ARRANGEMENTS Survival Craft Arrangements and Equipment § 180.137 Stowage of life floats and buoyant apparatus. (a) In addition to meeting § 180.130, each...

  20. 46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Inflatable liferafts and inflatable buoyant apparatus... SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable liferafts and inflatable buoyant apparatus. The number of the inflatable liferaft or inflatable...

  1. 46 CFR 160.010-4 - General requirements for buoyant apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false General requirements for buoyant apparatus. 160.010-4 Section 160.010-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for...

  2. 46 CFR 180.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Stowage of life floats and buoyant apparatus. 180.137... (UNDER 100 GROSS TONS) LIFESAVING EQUIPMENT AND ARRANGEMENTS Survival Craft Arrangements and Equipment § 180.137 Stowage of life floats and buoyant apparatus. (a) In addition to meeting § 180.130, each...

  3. 46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Inflatable liferafts and inflatable buoyant apparatus... SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable liferafts and inflatable buoyant apparatus. The number of the inflatable liferaft or inflatable...

  4. 46 CFR 160.010-4 - General requirements for buoyant apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for Merchant... of passing the tests in § 160.010-7. (b) Materials not covered in this subpart must be of good..., floating either side up. (d) Each buoyant apparatus must be of such size and strength that it can...

  5. Turbulence statistics in a negatively buoyant particle plume - laboratory measurement

    NASA Astrophysics Data System (ADS)

    Bordoloi, Ankur; Clark, Laura; Veliz, Gerardo; Heath, Michael; Variano, Evan

    2016-11-01

    Negatively buoyant plumes of nylon particles are investigated in quiescent salt-water solution using flow visualization and stereoscopic PIV. Particles of the size 2 mm are continuously released through a nozzle from the top inside a water tank using a screw-conveyor based release mechanism. The plume propagates downward due to gravity, and by virtue of interacting particle wakes, becomes turbulent. The two phases are refractive index matched, so that the velocity field in the interstitial fluid can be quantified using PIV. We examine the velocity fields in the fluid phase to characterize turbulence statistics, such as turbulent kinetic energy, Reynolds stresses in the fully developed region of the plume. Further, we develop an image processing method to obtain particle distribution and particle slip inside the plume. In the presentation, we will discuss these results in the light of existing literature for rising plumes of bubbles under similar experimental conditions.

  6. Buoyant surface jet analysis of the Yukon River

    NASA Technical Reports Server (NTRS)

    Gosink, J. P.

    1988-01-01

    Thermal infrared satellite imagery of the discharge from the Yukon River obtained on July 5, 1985 was compared with hydraulic theory for the dilution of buoyant surface jets. In a crossflow, the theory predicts that the plume will follow an x exp 1/3 trajectory where x is distance alongshore, and that the plume temperature will decay according to x exp - 1/6 due to mixing with the receiving water. Measurements of the Yukon River discharge indicate very good agreement with the predicted trajectory, and less, but acceptable, agreement with the predicted dilution. Large scale thermal fronts are also observable in the thermal imagery; the fronts may be associated with excursions of the plume due to tidal currents.

  7. Flow behaviour of negatively buoyant jets in immiscible ambient fluid

    NASA Astrophysics Data System (ADS)

    Geyer, A.; Phillips, J. C.; Mier-Torrecilla, M.; Idelsohn, S. R.; Oñate, E.

    2012-01-01

    In this paper we investigate experimentally the injection of a negatively buoyant jet into a homogenous immiscible ambient fluid. Experiments are carried out by injecting a jet of dyed fresh water through a nozzle in the base of a cylindrical tank containing rapeseed oil. The fountain inlet flow rate and nozzle diameter were varied to cover a wide range of Richardson Ri (8 × 10-4 < Ri < 1.98), Reynolds Re (467 < Re < 5,928) and Weber We (2.40 < We < 308.56) numbers. Based on the Re, Ri and We values for the experiments, we have determined a regime map to define how these values may control the occurrence of the observed flow types. Whereas Ri plays a stronger role when determining the maximum penetration height, the effect of the Reynolds number is stronger predicting the flow behaviour for a specific nozzle diameter and injection velocity.

  8. Development of surfaces repelling negatively buoyant solid particles

    NASA Astrophysics Data System (ADS)

    Semmler, Carina; Alexeev, Alexander

    2011-03-01

    Using a hybrid computational method that integrates the lattice Boltzmann model for fluid dynamics and the lattice spring model for solids, we examine the motion of negatively buoyant solid microparticles in shear flow near a solid wall decorated with regularly distributed rigid posts. The posts are arranged in a square pattern and tilted relative to the flow direction. We show that when rigid posts are tilted against flow, secondary flows emerge that prevent the deposition of suspended particles on the solid surface. We probe the effect of post geometry on the development of secondary flows and identify the optimal post architecture in terms of the mass of levitated solid particles. Our results are useful for designing anti-fouling surfaces that repel colloidal particles carried by fluid.

  9. Trace Metals and Nutrients in the Hudson River Buoyant Plume

    NASA Astrophysics Data System (ADS)

    Wright, D. D.; Reinfelder, J. R.; Chant, R. J.; Glenn, S. M.; Schofield, O.; Wilkin, J. L.; Houghton, R. W.; Chen, R. F.; Moline, M. A.; Frazier, T. K.

    2004-12-01

    In order to determine the spatial distribution and biological impacts of contaminant metals and nutrients associated with the Hudson River buoyant plume, the transport and transformations of mercury, other trace metals, and major nutrients are being measured as part of the LaGrangian Transport and Transformation Experiment (LaTTE). Beginning in the spring of 2004, a series of dye patch experiments will be carried out that will include continuous underway chemical and biological sampling within the well-sampled framework of an operational ocean observatory. During the first experiment in May 2004, surface water samples for dissolved and suspended particle concentrations of mercury, monomethylmercury, and bioactive and non-essential trace metals were collected using a trace metal clean, underway sampling system. A semi-continuous (5 min resolution) record of dissolved gaseous mercury (elemental mercury) in surface waters revealed diurnal patterns of mercury reduction and volatilization. The results of this project will improve predictions of contaminant movements and ecosystem impacts within the Middle Atlantic Bight.

  10. Transient buoyant convection from a discrete source in porous media

    NASA Astrophysics Data System (ADS)

    Moradi, Ali; Flynn, Morris

    2016-11-01

    The study of porous media filling box flows informs (i) the dissolution of non-aqueous phase liquids or sequestered CO2 into potable groundwater, (ii) leakage of contaminants from waste piles, and (iii) enhanced oil recovery technologies. Here we examine the flow of a negatively buoyant, laminar plume in a box filled with a porous medium, which is connected to an infinite external ambient via upper and lower fissures. As t -> ∞ , the box contains two uniform layers of different densities. However, the approach towards steady state is characterized by a lower (contaminated) layer that is continuously stratified and is governed by the ratios of the virtual origin correction and lower fissure depth to the box height, and the ratio, μ, of the draining timescale to the filling timescale. Whereas the presence of a continuous stratification in the contaminated layer for finite time poses analytical challenges, we show that it is possible to derive bounds on the range of possible solutions. A separate component of our study considers time-variable forcing where the plume source strength is either abruptly altered or turned on and off with fixed half-period. Throughout, comparisons are drawn against filling boxes driven by turbulent free plumes. NSERC, Carbon Management Canada.

  11. Role of buoyant flame dynamics in wildfire spread

    PubMed Central

    Finney, Mark A.; Cohen, Jack D.; Forthofer, Jason M.; McAllister, Sara S.; Gollner, Michael J.; Gorham, Daniel J.; Saito, Kozo; Akafuah, Nelson K.; Adam, Brittany A.; English, Justin D.

    2015-01-01

    Large wildfires of increasing frequency and severity threaten local populations and natural resources and contribute carbon emissions into the earth-climate system. Although wildfires have been researched and modeled for decades, no verifiable physical theory of spread is available to form the basis for the precise predictions needed to manage fires more effectively and reduce their environmental, economic, ecological, and climate impacts. Here, we report new experiments conducted at multiple scales that appear to reveal how wildfire spread derives from the tight coupling between flame dynamics induced by buoyancy and fine-particle response to convection. Convective cooling of the fine-sized fuel particles in wildland vegetation is observed to efficiently offset heating by thermal radiation until convective heating by contact with flames and hot gasses occurs. The structure and intermittency of flames that ignite fuel particles were found to correlate with instabilities induced by the strong buoyancy of the flame zone itself. Discovery that ignition in wildfires is critically dependent on nonsteady flame convection governed by buoyant and inertial interaction advances both theory and the physical basis for practical modeling. PMID:26183227

  12. Residence time of buoyant objects in drowning machines

    PubMed Central

    Gioia, Gustavo; Chakraborty, Pinaki; Gary, Stefan F.; Zamalloa, Carlo Zuñiga; Keane, Richard D.

    2011-01-01

    Hydraulic jumps are a common feature of rivers and waterways, where they can be found close to spillways, weirs, rocky ledges, and boulders. People adrift upstream of a hydraulic jump are liable to become trapped in the turbulent roller of the hydraulic jump. For this reason, hydraulic jumps have been termed “drowning machines” and are recognized as a public hazard. We use experiments and theory to show that on average a buoyant object spends a time τ/p trapped in a jump, where τ is the period of a harmonic process inherent in the jump, and p is the probability that the object will escape in any time interval τ. The probability p is governed by the statistical theory of extreme values and depends primarily on the ratio between the density of the object and the density of the fluid. We use our results to draw conclusions that might prove to be useful to public-safety agencies intent on carrying out tests in drowning machines. Our results can also be used to predict the amount of flotsam that accumulates at the toe of a hydraulic jump.

  13. Taylor-Couette flow instabilities in neutrally-buoyant suspensions

    NASA Astrophysics Data System (ADS)

    Majji, Madhu; Banerjee, Sanjoy; Morris, Jeffrey F.

    2016-11-01

    Experimentally-determined instabilities and flow states of a neutrally-buoyant suspension are described. The flow is studied in a concentric-cylinder device with inner-to-outer cylinder ratio of 0.877 with inner cylinder rotating and outer stationary. The cylinder length to annular gap ratio is 20, while the gap to particle size ratio is approximately 30, for spherical particles of 250 μm diameter. Using a slowly increasing or decreasing Re ramp, the flow agrees with all expectations for the pure fluid, while a slowly decreasing (quasi-static) ramp is used for the suspension flow, which is found to be unstable at lower Reynolds number Re (based on the effective viscosity) than pure fluid, and exhibits spiraling and ribbon states not found for a pure fluid with only inner cylinder rotating. Strikingly, the suspension at solid fraction ϕ >= 0 . 05 goes unstable first to a nonaxisymetric state rather than axisymmetric Taylor vortices. At 0 . 1 <= ϕ <= 0 , 2 , the flow exhibits numerous states during quais-static ramping of Re , while for ϕ = 0 . 3 , the base state Couette flow gives way to wavy spirals (WS) at Re 80 and exhibits only the WS state up to Re = 150 . Transient behavior on sudden change of Re and particle tracking will also be presented.

  14. The effect of particle properties on the depth profile of buoyant plastics in the ocean

    NASA Astrophysics Data System (ADS)

    Kooi, Merel; Reisser, Julia; Slat, Boyan; Ferrari, Francesco F.; Schmid, Moritz S.; Cunsolo, Serena; Brambini, Roberto; Noble, Kimberly; Sirks, Lys-Anne; Linders, Theo E. W.; Schoeneich-Argent, Rosanna I.; Koelmans, Albert A.

    2016-10-01

    Most studies on buoyant microplastics in the marine environment rely on sea surface sampling. Consequently, microplastic amounts can be underestimated, as turbulence leads to vertical mixing. Models that correct for vertical mixing are based on limited data. In this study we report measurements of the depth profile of buoyant microplastics in the North Atlantic subtropical gyre, from 0 to 5 m depth. Microplastics were separated into size classes (0.5–1.5 and 1.5–5.0 mm) and types (‘fragments’ and ‘lines’), and associated with a sea state. Microplastic concentrations decreased exponentially with depth, with both sea state and particle properties affecting the steepness of the decrease. Concentrations approached zero within 5 m depth, indicating that most buoyant microplastics are present on or near the surface. Plastic rise velocities were also measured, and were found to differ significantly for different sizes and shapes. Our results suggest that (1) surface samplers such as manta trawls underestimate total buoyant microplastic amounts by a factor of 1.04–30.0 and (2) estimations of depth-integrated buoyant plastic concentrations should be done across different particle sizes and types. Our findings can assist with improving buoyant ocean plastic vertical mixing models, mass balance exercises, impact assessments and mitigation strategies.

  15. The effect of particle properties on the depth profile of buoyant plastics in the ocean

    PubMed Central

    Kooi, Merel; Reisser, Julia; Slat, Boyan; Ferrari, Francesco F.; Schmid, Moritz S.; Cunsolo, Serena; Brambini, Roberto; Noble, Kimberly; Sirks, Lys-Anne; Linders, Theo E. W.; Schoeneich-Argent, Rosanna I.; Koelmans, Albert A.

    2016-01-01

    Most studies on buoyant microplastics in the marine environment rely on sea surface sampling. Consequently, microplastic amounts can be underestimated, as turbulence leads to vertical mixing. Models that correct for vertical mixing are based on limited data. In this study we report measurements of the depth profile of buoyant microplastics in the North Atlantic subtropical gyre, from 0 to 5 m depth. Microplastics were separated into size classes (0.5–1.5 and 1.5–5.0 mm) and types (‘fragments’ and ‘lines’), and associated with a sea state. Microplastic concentrations decreased exponentially with depth, with both sea state and particle properties affecting the steepness of the decrease. Concentrations approached zero within 5 m depth, indicating that most buoyant microplastics are present on or near the surface. Plastic rise velocities were also measured, and were found to differ significantly for different sizes and shapes. Our results suggest that (1) surface samplers such as manta trawls underestimate total buoyant microplastic amounts by a factor of 1.04–30.0 and (2) estimations of depth-integrated buoyant plastic concentrations should be done across different particle sizes and types. Our findings can assist with improving buoyant ocean plastic vertical mixing models, mass balance exercises, impact assessments and mitigation strategies. PMID:27721460

  16. The effect of particle properties on the depth profile of buoyant plastics in the ocean.

    PubMed

    Kooi, Merel; Reisser, Julia; Slat, Boyan; Ferrari, Francesco F; Schmid, Moritz S; Cunsolo, Serena; Brambini, Roberto; Noble, Kimberly; Sirks, Lys-Anne; Linders, Theo E W; Schoeneich-Argent, Rosanna I; Koelmans, Albert A

    2016-10-10

    Most studies on buoyant microplastics in the marine environment rely on sea surface sampling. Consequently, microplastic amounts can be underestimated, as turbulence leads to vertical mixing. Models that correct for vertical mixing are based on limited data. In this study we report measurements of the depth profile of buoyant microplastics in the North Atlantic subtropical gyre, from 0 to 5 m depth. Microplastics were separated into size classes (0.5-1.5 and 1.5-5.0 mm) and types ('fragments' and 'lines'), and associated with a sea state. Microplastic concentrations decreased exponentially with depth, with both sea state and particle properties affecting the steepness of the decrease. Concentrations approached zero within 5 m depth, indicating that most buoyant microplastics are present on or near the surface. Plastic rise velocities were also measured, and were found to differ significantly for different sizes and shapes. Our results suggest that (1) surface samplers such as manta trawls underestimate total buoyant microplastic amounts by a factor of 1.04-30.0 and (2) estimations of depth-integrated buoyant plastic concentrations should be done across different particle sizes and types. Our findings can assist with improving buoyant ocean plastic vertical mixing models, mass balance exercises, impact assessments and mitigation strategies.

  17. Supergranulation as the Sun's largest buoyantly driven mode of convection

    NASA Astrophysics Data System (ADS)

    Cossette, Jean-Francois; Rast, Mark

    2016-05-01

    Solar supergranulation has been characterized as horizontally divergent flow motions having a typical scale of 32 Mm using Doppler imaging, granule tracking and helioseismology. Unlike granules, the size of which is comparable to both the thickness of the radiative boundary layer and local scale height at the photosphere, supergranules do not appear to correspond to any particular length scale of the flow. Possible explanations ranging from convection theories involving Helium ionization to spatial correlation or self-organization of granular flows have been proposed as physical mechanisms to explain solar supergranulation. However, its existence remains largely a mystery. Remarkably, horizontal velocity power spectra obtained from Doppler imaging and correlation tracking of flow features at the solar surface reveal the presence of peaks corresponding to granular and supergranular scales, followed by a monotonic decrease in power at scales larger than supergranulation, which suggests that large-scale modes in the deep layers of the convection zone may be suppressed. Using 3D anelastic simulations of solar convection we investigate whether supergranulation may reflect the largest buoyantly driven mode of convection inside the Sun. Results show that the amount of kinetic energy contained in the largest flow scales relative to that associated with supergranular motions is a function of the depth of the transition from a convectively unstable to convectively stable mean stratification inside the simulation. This suggests that the observed monotonic decrease in power at scales larger than supergranulation may be explained by rapid cooling in the subphotospheric layers and an essentially isentropic solar interior, wherein convective driving is effectively suppressed.

  18. Buoyant subduction on Venus: Implications for subduction around coronae

    NASA Astrophysics Data System (ADS)

    Burt, J. D.; Head, J. W.

    1993-03-01

    Potentially low lithospheric densities, caused by high Venus surface and perhaps mantle temperatures, could inhibit the development of negative buoyancy-driven subduction and a global system of plate tectonics/crustal recycling on that planet. No evidence for a global plate tectonic system was found so far, however, specific features strongly resembling terrestrial subduction zones in planform and topographic cross-section were described, including trenches around large coronae and chasmata in eastern Aphrodite Terra. The cause for the absence, or an altered expression, of plate tectonics on Venus remains to be found. Slab buoyancy may play a role in this difference, with higher lithospheric temperatures and a tendency toward positive buoyancy acting to oppose the descent of slabs and favoring under thrusting instead. The effect of slab buoyancy on subduction was explored and the conditions which would lead to under thrusting versus those allowing the formation of trenches and self-perpetuating subduction were defined. Applying a finite element code to assess the effects of buoyant forces on slabs subducting into a viscous mantle, it was found that mantle flow induced by horizontal motion of the convergent lithosphere greatly influences subduction angle, while buoyancy forces produce a lesser effect. Induced mantle flow tends to decrease subduction angle to near an under thrusting position when the subducting lithosphere converges on a stationary overriding lithosphere. When the overriding lithosphere is in motion, as in the case of an expanding corona, subduction angles are expected to increase. An initial stage involved estimating the changes in slab buoyancy due to slab healing and pressurization over the course of subduction. Modeling a slab, descending at a fixed angle and heated by conduction, radioactivity, and the heat released in phase changes, slab material density changes due to changing temperature, phase, and pressure were derived.

  19. Buoyant subduction on Venus: Implications for subduction around coronae

    NASA Technical Reports Server (NTRS)

    Burt, J. D.; Head, J. W.

    1993-01-01

    Potentially low lithospheric densities, caused by high Venus surface and perhaps mantle temperatures, could inhibit the development of negative buoyancy-driven subduction and a global system of plate tectonics/crustal recycling on that planet. No evidence for a global plate tectonic system was found so far, however, specific features strongly resembling terrestrial subduction zones in planform and topographic cross-section were described, including trenches around large coronae and chasmata in eastern Aphrodite Terra. The cause for the absence, or an altered expression, of plate tectonics on Venus remains to be found. Slab buoyancy may play a role in this difference, with higher lithospheric temperatures and a tendency toward positive buoyancy acting to oppose the descent of slabs and favoring under thrusting instead. The effect of slab buoyancy on subduction was explored and the conditions which would lead to under thrusting versus those allowing the formation of trenches and self-perpetuating subduction were defined. Applying a finite element code to assess the effects of buoyant forces on slabs subducting into a viscous mantle, it was found that mantle flow induced by horizontal motion of the convergent lithosphere greatly influences subduction angle, while buoyancy forces produce a lesser effect. Induced mantle flow tends to decrease subduction angle to near an under thrusting position when the subducting lithosphere converges on a stationary overriding lithosphere. When the overriding lithosphere is in motion, as in the case of an expanding corona, subduction angles are expected to increase. An initial stage involved estimating the changes in slab buoyancy due to slab healing and pressurization over the course of subduction. Modeling a slab, descending at a fixed angle and heated by conduction, radioactivity, and the heat released in phase changes, slab material density changes due to changing temperature, phase, and pressure were derived.

  20. Structure and Soot Properties of Non-Buoyant Laminar Round-Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Mortazavi, Saeed; Sunderland, Peter B.; Jurng, Jongsoo; Faeth, Gerard M.

    1993-01-01

    The structure and soot properties of nonbuoyant laminar diffusion flames are being studied experimentally and theoretically in order to better understand the soot and thermal radiation emissions from luminous flames. The measurements involve weakly-buoyant flames at low pressure in normal gravity (ng) and nonbuoyant flames at normal pressures in microgravity (micro g). The objectives of the present investigation are to study the differences of soot properties between nonbuoyant and buoyant diffusion flames, and to evaluate predictions based on the laminar flamelet approach.

  1. Note: Buoyant-force assisted liquid membrane electrochemical etching for nano-tip preparation

    NASA Astrophysics Data System (ADS)

    Zeng, Yongbin; Wang, Yufeng; Wu, Xiujuan; Xu, Kun; Qu, Ningsong

    2014-12-01

    A liquid membrane electrochemical etching process for preparing nano-tips is proposed by the introduction of buoyant force to the lower tip, in which the lower portion of the anodic wire is immersed into a floating layer. A mathematical model of this method is derived. Both calculation and experimental results demonstrate that the introduction of buoyant force can significantly decrease the tip radius. The lubricating oil and deionized water floating layers were tested for the processing of nano-tips. Further, high-aspect-ratio nano-electrodes were prepared by applying a relative vertical movement to the anodic wire.

  2. Preliminary study of ground handling characteristics of Buoyant Quad Rotor (BQR) vehicles

    NASA Technical Reports Server (NTRS)

    Browning, R. G. E.

    1980-01-01

    A preliminary investigation of mooring concepts appropriate for heavy lift buoyant quad rotor (BQR) vehicles was performed. A review of the evolution of ground handling systems and procedures for all airship types is presented to ensure that appropriate consideration is given to past experiences. Two buoyant quad rotor designs are identified and described. An analysis of wind loads on a moored airship and the effects of these loads on vehicle design is provided. Four mooring concepts are assessed with respect to the airship design, wind loads and mooring site considerations. Basing requirements and applicability of expeditionary mooring at various operational scenarios are addressed.

  3. Effect of Technology Enhanced Conceptual Change Texts on Students' Understanding of Buoyant Force

    ERIC Educational Resources Information Center

    Ozkan, Gulbin; Selcuk, Gamze Sezgin

    2015-01-01

    In this study, the effect of technology enhanced conceptual change texts on elementary school students' understanding of buoyant force was investigated. The conceptual change texts (written forms) used in this study are proven for effectiveness and are enriched by using technology support in this study. These texts were tried out on two groups. A…

  4. The Effect of an Externally Attached Neutrally Buoyant Transmitter on Mortal Injury during Simulated Hydroturbine Passage

    SciTech Connect

    Brown, Richard S.; Pflugrath, Brett D.; Carlson, Thomas J.; Deng, Zhiqun

    2012-02-03

    On their seaward migration, juvenile salmonids commonly pass hydroelectric dams. Fish passing through hydroturbines experience a rapid decrease in pressure as they pass by the turbine blade and the severity of this decompression can be highly variable. This rapid decrease in pressure can result in injuries such as swim bladder rupture, exophthalmia, and emboli and hemorrhaging in the fins and tissues. However, recent research indicates that the presence of a telemetry tag (acoustic, radio, inductive) implanted inside the coelom of a juvenile salmon increases the likelihood that the fish will be injured or die during turbine passage. Thus, previous research conducted using telemetry tags implanted into the coelom of fish may have been inaccurate. Thus, a new technique is needed to provide unbiased estimates of survival through turbines. This research provides an evaluation of the effectiveness of a neutrally buoyant externally attached acoustic transmitter. Both nontagged fish and fish tagged with a neutrally buoyant external transmitter were exposed to a range of rapid decompressions simulating turbine passage. Juvenile Chinook salmon tagged with a neutrally buoyant externally attached acoustic transmitter did not receive a higher degree of barotrauma than their nontagged counterparts. We suggest that future research include field-based comparisons of survival and behavior among fish tagged with a neutrally buoyant external transmitter and those internally implanted with transmitters.

  5. Applying a predict-observe-explain sequence in teaching of buoyant force

    NASA Astrophysics Data System (ADS)

    Radovanović, Jelena; Sliško, Josip

    2013-01-01

    An active learning sequence based on the predict-observe-explain teaching strategy is applied to a lesson on buoyant force. The results obtained clearly justify the use of this teaching method and suggest devising a series of activities to enable more effective removal of students’ commonly held alternative conceptions regarding floating and sinking.

  6. 46 CFR 185.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... liferafts, inflatable buoyant apparatus, inflatable life jackets, and inflated rescue boats. (a) An... inflated rescue boats must be in accordance with the manufacturer's instructions. All repairs must be...

  7. 46 CFR 122.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST GUARD..., inflatable life jackets, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant... other standard specified by the Commandant. (e) Repair and maintenance of inflated rescue boats must...

  8. 46 CFR 185.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... liferafts, inflatable buoyant apparatus, inflatable life jackets, and inflated rescue boats. (a) An... inflated rescue boats must be in accordance with the manufacturer's instructions. All repairs must be...

  9. 46 CFR 122.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST GUARD..., inflatable life jackets, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant... other standard specified by the Commandant. (e) Repair and maintenance of inflated rescue boats must...

  10. 46 CFR 185.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... liferafts, inflatable buoyant apparatus, inflatable life jackets, and inflated rescue boats. (a) An... inflated rescue boats must be in accordance with the manufacturer's instructions. All repairs must be...

  11. 46 CFR 122.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST GUARD..., inflatable life jackets, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant... other standard specified by the Commandant. (e) Repair and maintenance of inflated rescue boats must...

  12. 3D Numerical Simulation of Turbulent Buoyant Flow and Heat Transport in a Curved Open Channel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A three-dimensional buoyancy-extended version of kappa-epsilon turbulence model was developed for simulating the turbulent flow and heat transport in a curved open channel. The density- induced buoyant force was included in the model, and the influence of temperature stratification on flow field was...

  13. 46 CFR 117.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Stowage of life floats and buoyant apparatus. 117.137 Section 117.137 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS... EQUIPMENT AND ARRANGEMENTS Survival Craft Arrangements and Equipment § 117.137 Stowage of life floats...

  14. Buoyant plumes from solute gradients generated by non-motile Escherichia coli

    NASA Astrophysics Data System (ADS)

    Benoit, M. R.; Brown, R. B.; Todd, P.; Nelson, E. S.; Klaus, D. M.

    2008-12-01

    The effect of hydrodynamic mixing in bacterial populations due to bacterial chemotaxis is a well-described phenomenon known as bioconvection. Here we report the observation of buoyant plumes that result in hydrodynamic mixing, but in contrast to bioconvection the plumes form in the absence of bacterial motility. We propose that the buoyant flow originates from solute gradients created by bacterial metabolism, similar to solute-induced buoyant flow around growing protein crystals. In our experiments, metabolically-active non-motile Escherichia coli were layered along the bottom of flat-bottomed containers. The E. coli consumed glucose in the medium creating a lighter fluid beneath a heavier fluid. The situation is an example of Rayleigh-Taylor instability, in which a lighter fluid pushes on a heavier one. We developed a numerical model to study the effect of E. coli nutrient consumption and by-product excretion on extracellular solute gradients. The model solutions showed reduced-density fluid along the bottom of the fluid domain leading to buoyant plumes, which were qualitatively similar to the experimental plumes. We also used scaling analyses to study the dependence of plume formation on container size and cell size, and to investigate the effect of reduced gravity, such as the microgravity conditions encountered during spaceflight.

  15. 46 CFR 122.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts, inflatable buoyant apparatus... apparatus must be serviced at a facility specifically approved by the Commandant for the particular brand... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST...

  16. 46 CFR 122.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts, inflatable buoyant apparatus... apparatus must be serviced at a facility specifically approved by the Commandant for the particular brand... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST...

  17. 46 CFR 185.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... inflatable liferaft or inflatable buoyant apparatus must be serviced at a facility specifically approved by... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of...

  18. 46 CFR 185.730 - Servicing of inflatable liferafts, inflatable buoyant apparatus, inflatable life jackets, and...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... inflatable liferaft or inflatable buoyant apparatus must be serviced at a facility specifically approved by... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of...

  19. Applying a Predict-Observe-Explain Sequence in Teaching of Buoyant Force

    ERIC Educational Resources Information Center

    Radovanovic, Jelena; Slisko, Josip

    2013-01-01

    An active learning sequence based on the predict-observe-explain teaching strategy is applied to a lesson on buoyant force. The results obtained clearly justify the use of this teaching method and suggest devising a series of activities to enable more effective removal of students' commonly held alternative conceptions regarding floating and…

  20. Buoyant plumes from solute gradients generated by non-motile Escherichia coli.

    PubMed

    Benoit, M R; Brown, R B; Todd, P; Nelson, E S; Klaus, D M

    2008-12-10

    The effect of hydrodynamic mixing in bacterial populations due to bacterial chemotaxis is a well-described phenomenon known as bioconvection. Here we report the observation of buoyant plumes that result in hydrodynamic mixing, but in contrast to bioconvection the plumes form in the absence of bacterial motility. We propose that the buoyant flow originates from solute gradients created by bacterial metabolism, similar to solute-induced buoyant flow around growing protein crystals. In our experiments, metabolically-active non-motile Escherichia coli were layered along the bottom of flat-bottomed containers. The E. coli consumed glucose in the medium creating a lighter fluid beneath a heavier fluid. The situation is an example of Rayleigh-Taylor instability, in which a lighter fluid pushes on a heavier one. We developed a numerical model to study the effect of E. coli nutrient consumption and by-product excretion on extracellular solute gradients. The model solutions showed reduced-density fluid along the bottom of the fluid domain leading to buoyant plumes, which were qualitatively similar to the experimental plumes. We also used scaling analyses to study the dependence of plume formation on container size and cell size, and to investigate the effect of reduced gravity, such as the microgravity conditions encountered during spaceflight.

  1. A study of the accuracy of neutrally buoyant bubbles used as flow tracers in air

    NASA Technical Reports Server (NTRS)

    Kerho, Michael F.

    1993-01-01

    Research has been performed to determine the accuracy of neutrally buoyant and near neutrally buoyant bubbles used as flow tracers in air. Theoretical, computational, and experimental results are presented to evaluate the dynamics of bubble trajectories and factors affecting their ability to trace flow-field streamlines. The equation of motion for a single bubble was obtained and evaluated using a computational scheme to determine the factors which affect a bubble's trajectory. A two-dimensional experiment was also conducted to experimentally determine bubble trajectories in the stagnation region of NACA 0012 airfoil at 0 deg angle of attack using a commercially available helium bubble generation system. Physical properties of the experimental bubble trajectories were estimated using the computational scheme. These properties included the density ratio and diameter of the individual bubbles. the helium bubble system was then used to visualize and document the flow field about a 30 deg swept semispan wing with simulated glaze ice. Results were compared to Navier-Stokes calculations and surface oil flow visualization. The theoretical and computational analysis have shown that neutrally buoyant bubbles will trace even the most complex flow patterns. Experimental analysis revealed that the use of bubbles to trace flow patterns should be limited to qualitative measurements unless care is taken to ensure neutral buoyancy. This is due to the difficulty in the production of neutrally buoyant bubbles.

  2. Growth and buoyant density of Escherichia coli at very low osmolarities.

    PubMed

    Baldwin, W W; Myer, R; Kung, T; Anderson, E; Koch, A L

    1995-01-01

    The growth and buoyant densities of two closely related strains of Escherichia coli in M9-glucose medium that was diluted to produce osmolarities that varied from as low as 5 to 500 mosM were monitored. At 15 mosM, the lowest osmolarity at which buoyant density could be measured reproducibly in Percoll gradients, both ML3 and ML308 had a buoyant density of about 1.079 g/ml. As the osmolarity of the medium was increased, the buoyant density also increased linearly up to about 125 mosM, at which the buoyant density was 1.089 g/ml. From 150 up to 500 mosM, the buoyant density again increased linearly but with a different slope from that seen at the lower osmolarities. The buoyant density at 150 mosM was about 1.091 g/ml, and at 500 mosM it was 1.101 g/ml. Both strains of E. coli could be grown in M9 medium diluted 1:1 with water, with an osmolarity of 120 mosM, but neither strain grew in 1:2-diluted M9 if the cells were pregrown in undiluted M9. (Note: undiluted M9 as prepared here has an osmolarity of about 250 mosM.) However, if the cells were pregrown in 30% M9, about 75 mosM, they would then grow in M9 at 45 mosM and above but not below 40 mosM. To determine which constituent of M9 medium was being diluted to such a low level that it inhibited growth, diluted M9 was prepared with each constituent added back singly. From this study, it was determined that both Ca2+ and Mg2+ could stimulate growth below 40 mosM. With Ca2+ - and Mg2+ -supplemented diluted M9 and cells pregrown in 75 mosM M9, it was possible to grow ML308 in 15 mosM M9. Strain ML3 would only haltingly grow at 15 mosM. Four attempts were made to grow both ML3 and ML308 at 5 mosM. In three of the experiments, ML308 grew, while strain ML3 grew in one experiment. While our experiments were designed to effect variations in medium osmolarity by using NaCl as an osmotic agent, osmolarity and salinity were changed concurrently. Therefore, from this study, we believe that E. coli might be defined as an

  3. The influence of shelfbreak forcing on the alongshelf penetration of the Danube buoyant water, Black sea

    NASA Astrophysics Data System (ADS)

    Yankovsky, Alexander E.; Lemeshko, Evgeny M.; Ilyin, Yuriy P.

    2004-06-01

    The buoyancy-driven coastal current propagating along the western coast in the Black Sea is forced by the discharge of several major European rivers including the Danube, Dnepr and South Bug. In this study, we present observational evidence that the buoyant water alongshelf penetration is strongly affected by shelfbreak mesoscale features associated with the Rim Current dynamics. The Rim Current is a major element of the Black Sea general circulation, typically following isobaths over the upper-to-middle slope. Two hydrographic surveys conducted in 1992 and 1994 have been chosen among available archive data for the detailed analysis. In both years, though Danube buoyant discharge was similar prior to the beginning of shipboard observations (varying around 7000 m 3 s -1), the buoyant water exhibited very different downstream (that is, in the direction of Kelvin wave) penetration. In 1992, it spread all the way around the southwestern corner of the Black Sea basin and then further eastward past the Bosporus Strait. In contrast, its downstream penetration was blocked in 1994 and buoyant water did not even reach Cape Kaliakra on the Bulgarian coast. This difference was related to the shelfbreak processes. In 1992, the cyclonic meander of the Rim Current merged with the coastal buoyant water thus promoting its advection from Cape Kaliakra downstream. In 1994, a strong anticyclone in the southwestern corner of the Black Sea completely blocked the propagation of a buoyancy-driven current past Cape Kaliakra. In addition, another anticyclone in the northwestern part of the sea advected buoyant water offshore to the central area of the northwestern shelf. The positions of anticyclonic eddies during a period of observations was confirmed by remote sensing data. As these and other examples indicate, coastal buoyancy driven currents can be effectively blocked and dispersed offshore by the shelfbreak anticyclones if the shelf width allows their interaction with buoyant water

  4. Migration of buoyant non-wetting fluids in heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Huber, C.; Parmigiani, A.; Faroughi, S. A.; Bachmann, O.; Karani, H.

    2015-12-01

    The buoyant migration of a non-wetting fluid in porous media occurs in several natural contexts, such as during CO2 sequestration, methane in cold seeps, DNAPLs infiltration in groundwater, oil recovery and magma chambers. In this study, we use numerical modeling and laboratory experiments to investigate the migration of buoyant non-wetting fluids in time-dependent (reactive) or spatially heterogeneous porous media. We find that the stress balance at the pore scale greatly influences the migration dynamics and regime of viscous energy dissipation of the flow (low Re) and therefore impacts the transport of non-wetting fluid even at the field scale. We consider two complementary pore-scale studies. In the first case, the migration of the non-wetting fluid is impacted by the concurrent dissolution of the porous medium because of the reactivity of the buoyant invading fluid. In the second scenario a chemically inert buoyant non-wetting fluid migrates across an heterogeneous medium, from a low porosity (and permeability) layer into a high porosity (high permeability) layer. We find that these two cases lead to a similar and counter-intuitive outcome: the migration of the buoyant non-wetting fluid is reduced at high porosity/permeability. These counter-intuitive results stem from the effect of confinement of the non-wetting fluid (volume available for invasion) and viscosity ratio between the immiscible fluids on the fluid migration at the pore scale. An important solid confinement (low porosity) stabilizes fingering pathways and promotes efficient transport, while high porosity promotes the formation of an emulsion with discrete bubbles or slugs of non-wetting fluids.

  5. Smoke-Point Properties of Non-Buoyant Round Laminar Jet Diffusion Flames. Appendix J

    NASA Technical Reports Server (NTRS)

    Urban, D. L.; Yuan, Z.-G.; Sunderland, P. B.; Lin, K.-C.; Dai, Z.; Faeth, G. M.

    2000-01-01

    The laminar smoke-point properties of non-buoyant round laminar jet diffusion flames were studied emphasizing results from long-duration (100-230 s) experiments at microgravity carried out in orbit aboard the space shuttle Columbia. Experimental conditions included ethylene- and propane-fueled flames burning in still air at an ambient temperature of 300 K, pressures of 35-130 kPa, jet exit diameters of 1.6 and 2.7 mm, jet exit velocities of 170-690 mm/s, jet exit Reynolds numbers of 46-172, characteristic flame residence times of 40-302 ms, and luminous flame lengths of 15-63 mm. Contrary to the normal-gravity laminar smoke point, in microgravity, the onset of laminar smoke-point conditions involved two flame configurations: closed-tip flames with soot emissions along the flame axis and open-tip flames with soot emissions from an annular ring about the flame axis. Open-tip flames were observed at large characteristic flame residence times with the onset of soot emissions associated with radiative quenching near the flame tip: nevertheless, unified correlations of laminar smoke-point properties were obtained that included both flame configurations. Flame lengths at laminar smoke-point conditions were well correlated in terms of a corrected fuel flow rate suggested by a simplified analysis of flame shape. The present steady and non-buoyant flames emitted soot more readily than non-buoyant flames in earlier tests using ground-based microgravity facilities and than buoyant flames at normal gravity, as a result of reduced effects of unsteadiness, flame disturbances, and buoyant motion. For example, present measurements of laminar smoke-point flame lengths at comparable conditions were up to 2.3 times shorter than ground-based microgravity measurements and up to 6.4 times shorter than buoyant flame measurements. Finally, present laminar smoke-point flame lengths were roughly inversely proportional to pressure to a degree that is a somewhat smaller than observed during

  6. Parameter Estimation for a Turbulent Buoyant Jet Using Approximate Bayesian Computation

    NASA Astrophysics Data System (ADS)

    Christopher, Jason D.; Wimer, Nicholas T.; Hayden, Torrey R. S.; Lapointe, Caelan; Grooms, Ian; Rieker, Gregory B.; Hamlington, Peter E.

    2016-11-01

    Approximate Bayesian Computation (ABC) is a powerful tool that allows sparse experimental or other "truth" data to be used for the prediction of unknown model parameters in numerical simulations of real-world engineering systems. In this presentation, we introduce the ABC approach and then use ABC to predict unknown inflow conditions in simulations of a two-dimensional (2D) turbulent, high-temperature buoyant jet. For this test case, truth data are obtained from a simulation with known boundary conditions and problem parameters. Using spatially-sparse temperature statistics from the 2D buoyant jet truth simulation, we show that the ABC method provides accurate predictions of the true jet inflow temperature. The success of the ABC approach in the present test suggests that ABC is a useful and versatile tool for engineering fluid dynamics research.

  7. Buoyant Jets in Stratification; Mixing Efficiencies, Entropy Conditions and Wall Effects

    NASA Astrophysics Data System (ADS)

    Tzou, Chung-Nan; Camassa, Roberto; Durbin, Marlow; McLaughlin, Richard; Ward, Jeremy; Whetstone, Cole; White, Brian; UNC Joint Fluids Lab Team

    2013-11-01

    An exact integral solution to the steady buoyant jet closure model in linearly stratified ambient environment is derived so that in the limit of a sharply stratified environment an entropy (nonlinear jump) condition can be established. Comparing the density evolution for the buoyant jet in the extremes of linear and sharp stratification using experiments and exact formulas, mixing efficiencies can be assessed. In turn, wall effects are explored experimentally in sharp stratification and compared to the closure theory. Lastly, the modeling of entrainment in these systems will be revisited. DMS-0502266, NSF RTG DMS-0943851, NSF RAPID CBET-1045653, NSF CMG ARC- 1025523, and NSF DMS-1009750, ONR DURIP N00014-09-1-0840.

  8. Evidence for osmoregulation of cell growth and buoyant density in Escherichia coli

    SciTech Connect

    Baldwin, W.W.; Kubitschek, H.E.

    1984-07-01

    The buoyant density of cells of Escherichia coli B/r NC32 increased with the osmolarity of the growth medium. Growth rate and its variability were also dependent upon the osmolarity of the medium. Maximum growth rates and minimum variability of these rates were obtained in Luria broth by addition of NaCl to a concentration of about 0.23 M. 6 references, 1 figure, 1 table.

  9. The early melting of closed duplex DNA: analysis by banding in buoyant neutral rubidium trichloroacetate.

    PubMed Central

    Burke, R L; Bauer, W R

    1980-01-01

    Aqueous RbTCA permits the buoyant banding of both native and denatured DNA at room temperature and neutral pH. A unique property of this solvent is the bouyant resolution of closed circular, underwound DNA (I) from the corresponding nicked (II) species. Conditions are reported here in which PM-2 DNA I is physically resolved from native PM-2 DNA II, the buoyant separation being 1.27 mq/ml in 3.3 M RbTCA at 25 degrees C. The separation between nicked and closed DNAs increases with temperature up to 35.5 degrees C, at which PM-2 DNA II cooperatively melts and subsequently pellets. The isothermal buoyant density of a cloed DNA increases linearly as the linking number (Lk) of the closed DNA decreases. The early melting of closed DNA may be monitored with high precision by buoyant banding in RbTCA, it being possible to detect the disruption of as few as 40 base pairs in PM-2 DNA (10,000 base pairs). The constraint that the linking number be conserved in closed DNA requires that a change in duplex winding be accompanied by a compensating change in supercoiling. We estimate the linking number deficiency of PM-2 DNA I to be 0.094 turns per decibase pair. This result permits the estimation of the EtdBr unwinding angle, phi, by comparison with alternative determinations of the linking number deficiency which depend upom the value of phi. The result obtained here is that phi = 27.7 degrees +/- 0.5 degrees and is approximately independent of temperature over the range 15 degrees-35 degrees. PMID:7443544

  10. A buoyant plume adjacent to a headland-Observations of the Elwha River plume

    USGS Publications Warehouse

    Warrick, J.A.; Stevens, A.W.

    2011-01-01

    Small rivers commonly discharge into coastal settings with topographic complexities - such as headlands and islands - but these settings are underrepresented in river plume studies compared to more simplified, straight coasts. The Elwha River provides a unique opportunity to study the effects of coastal topography on a buoyant plume, because it discharges into the Strait of Juan de Fuca on the western side of its deltaic headland. Here we show that this headland induces flow separation and transient eddies in the tidally dominated currents (O(100. cm/s)), consistent with other headlands in oscillatory flow. These flow conditions are observed to strongly influence the buoyant river plume, as predicted by the "small-scale" or "narrow" dynamical classification using Garvine's (1995) system. Because of the transient eddies and the location of the river mouth on the headland, flow immediately offshore of the river mouth is directed eastward twice as frequently as it is westward. This results in a buoyant plume that is much more frequently "bent over" toward the east than the west. During bent over plume conditions, the plume was attached to the eastern shoreline while having a distinct, cuspate front along its westernmost boundary. The location of the front was found to be related to the magnitude and direction of local flow during the preceding O(1. h), and increases in alongshore flow resulted in deeper freshwater mixing, stronger baroclinic anomalies, and stronger hugging of the coast. During bent over plume conditions, we observed significant convergence of river plume water toward the frontal boundary within 1. km of the river mouth. These results show how coastal topography can strongly influence buoyant plume behavior, and they should assist with understanding of initial coastal sediment dispersal pathways from the Elwha River during a pending dam removal project. ?? 2010.

  11. BUOYANT MAGNETIC LOOPS IN A GLOBAL DYNAMO SIMULATION OF A YOUNG SUN

    SciTech Connect

    Nelson, Nicholas J.; Toomre, Juri; Brown, Benjamin P.; Brun, Allan Sacha

    2011-10-01

    The current dynamo paradigm for the Sun and Sun-like stars places the generation site for strong toroidal magnetic structures deep in the solar interior. Sunspots and starspots on Sun-like stars are believed to arise when sections of these magnetic structures become buoyantly unstable and rise from the deep interior to the photosphere. Here, we present the first three-dimensional global magnetohydrodynamic (MHD) simulation in which turbulent convection, stratification, and rotation combine to yield a dynamo that self-consistently generates buoyant magnetic loops. We simulate stellar convection and dynamo action in a spherical shell with solar stratification, but rotating three times faster than the current solar rate. Strong wreaths of toroidal magnetic field are realized by dynamo action in the convection zone. By turning to a dynamic Smagorinsky model for subgrid-scale turbulence, we here attain considerably reduced diffusion in our simulation. This permits the regions of strongest magnetic field in these wreaths to rise toward the top of the convection zone via a combination of magnetic buoyancy instabilities and advection by convective giant cells. Such a global simulation yielding buoyant loops represents a significant step forward in combining numerical models of dynamo action and flux emergence.

  12. The effect of soot modeling on thermal radiation in buoyant turbulent diffusion flames

    NASA Astrophysics Data System (ADS)

    Snegirev, A.; Kokovina, E.; Tsoy, A.; Harris, J.; Wu, T.

    2016-09-01

    Radiative impact of buoyant turbulent diffusion flames is the driving force in fire development. Radiation emission and re-absorption is controlled by gaseous combustion products, mainly CO2 and H2O, and by soot. Relative contribution of gas and soot radiation depends on the fuel sooting propensity and on soot distribution in the flame. Soot modeling approaches incorporated in big commercial codes were developed and calibrated for momentum-dominated jet flames, and these approaches must be re-evaluated when applied to the buoyant flames occurring in fires. The purpose of this work is to evaluate the effect of the soot models available in ANSYS FLUENT on the predictions of the radiative fluxes produced by the buoyant turbulent diffusion flames with considerably different soot yields. By means of large eddy simulations, we assess capability of the Moss-Brooks soot formation model combined with two soot oxidation submodels to predict methane- and heptane-fuelled fires, for which radiative flux measurements are available in the literature. We demonstrate that the soot oxidation models could be equally important as soot formation ones to predict the soot yield in the overfire region. Contribution of soot in the radiation emission by the flame is also examined, and predicted radiative fluxes are compared to published experimental data.

  13. Influence of Buoyant Convection on the Stability of Enclosed Laminar Flames

    NASA Technical Reports Server (NTRS)

    Brooker, John E.; Jia, Kezhong; Stocker, Dennis P.; Chen. Lea-Der

    1999-01-01

    Enclosed diffusion flames are commonly found in practical combustion systems, such as the power-plant combustor, gas turbine combustor, and jet engine after-burner. In these systems, fuel is injected into a duct with a co-flowing or cross-flowing air stream. In combustors, this flame is anchored at the burner (i.e., fuel jet inlet) unless adverse conditions cause the flame to lift off or blow out. Investigations of burner stability study the lift off, reattachment, and blow out of the flame. There have been numerous studies of flame stability. Relatively few studies have investigated the stability of flames with an oxidizer co-flow, compared with the number of studies on (nearly) free jet diffusion flames. The air flow around the fuel jet can significantly alter the lift off, reattachment and blow out of the jet diffusion flame. In normal gravity, however, the effects of the air flow on flame stability are often complicated by the presence of buoyant convection. A comparison of normal-gravity and microgravity flames can provide clear indication of the influence of forced and buoyant flows on the flame stability. The overall goal of the Enclosed Laminar Flames (ELF) research, described at the following URL site: http://zeta.lerc.nasa.gov/expr/elf.htm, is to improve our understanding of the effects of buoyant convection on the structure and stability of co-flow diffusion flames.

  14. On the Alignment of Strain, Vorticity and Scalar Gradient in Turbulent, Buoyant, Nonpremixed Flames

    NASA Technical Reports Server (NTRS)

    Boratav, O. N.; Elghobashi, S. E.; Zhong, R.

    1999-01-01

    The alignment of vorticity and scalar gradient with the eigendirections of the rate of strain tensor is investigated in turbulent buoyant nonpremixed horizontal and vertical flames. The uniqueness of a buoyant nonpremixed flame is that it contains regions with distinct alignment characteristics. The strain-enstrophy angle Psi is used to identify these regions. Examination of the vorticity field and the vorticity production in these different regions indicates that Psi and consequently the alignment properties near the flame surface identified by the mixture fraction band F approximately equals F(sub st) differ from those in the fuel region, F > F(sub st) and the oxidizer region, F < F(sub st). The F approximately equals F(sub st) band shows strain-dominance resulting in vorticity/alpha alignment while F > F(sub st) (and F < F(sub st) for the vertical flame) band(s) show(s) vorticity/beta alignment. The implication of this result is that the scalar dissipation, epsilon(sub F), attains its maximum value always near F approximately equals F(sub st). These results are also discussed within the framework of recent dynamical results [Galanti et al., Nonlinearity 10, 1675 (1997)] suggesting that the Navier-Stokes equations evolved towards an attracting solution. It is shown that the properties of such an attracting solution are also consistent with our results of buoyant turbulent nonpremixed flames.

  15. Onshore propagation of a buoyant ocean front observed using a shore-based marine radar

    NASA Astrophysics Data System (ADS)

    Marmorino, G. O.; Cooper, A. L.; Mied, R. P.; Lindemann, G. J.; Trizna, D. B.; Porter, D. L.

    2004-06-01

    An analysis is presented of a 2-h-long time series of X-band marine radar images, collected at Duck, North Carolina (USA), that captured the evolution of a buoyant ocean front as it propagated onshore, following a period of upwelling-favorable winds. In plan view, the front exhibits a scallop-shaped structure similar to that previously observed along strongly convergent fronts. This alongshore structure consists of broad frontal crests (a few hundred meters in length) alternating with sharply angled troughs, or frontal cusps. The evolution of these frontal shapes is explored using a reduced-gravity model (Cooper et al., J. Geophys. Res.-Oceans 106 (2001) 16887) that allows for nonlinear self-interaction of a propagating front. A model simulation shows cusps that develop quickly from initially broad troughs and that point toward the buoyant water, features resembling the observations. However, the simulation also shows a continuous oscillation of frontal shapes, while the observed front reaches a quasi-steady plan form. We attribute this difference in behavior to the gradual shoaling of the observed front as it steadily advances, ultimately reaching water depths of less than 2 m, which is comparable to the thickness of the buoyant layer. As a consequence of the shoaling, we suggest the cusps become sites of enhanced mixing, where water inshore of the front is also accelerated seaward.

  16. Observations of currents and density structure across a buoyant plume front

    USGS Publications Warehouse

    Gelfenbaum, G.; Stumpf, R.P.

    1993-01-01

    Observations of the Mobile Bay, Alabama, plume during a flood event in April 1991 reveal significant differences in the current field on either side of a front associated with the buoyant plume. During a strong southeasterly wind, turbid, low salinity water from Mobile Bay was pushed through an opening in the west side of the ebb-tidal delta and moved parallel to the coast. A stable front developed between the low salinity water of the buoyant plume (11???) and the high salinity coastal water (>23???) that was being forced landward by the prevailing winds. Despite the shallow water depth of 6 m, measurements of currents, temperature, and salinity show large shears and density gradients in both the vertical and the horizontal directions. At a station outside of the buoyant plume, currents at 0.5 m and 1.5 m below the surface were in the same direction as the wind. Inside the plume, however, currents at 0.5 m below the surface were parallel to the coast, 45??, off the direction of the wind and the magnitude was 45% larger than the magnitude of the surface currents outside the plume. Beneath the level of the plume, the currents were identical to the wind-driven currents in the ambient water south of the front. Our observations suggest that the wind-driven surface currents of the ambient water converged with the buoyant plume at the front and were subducted beneath the plume. The motion of the ambient coastal surface water was in the direction of the local wind stress, however, the motion of the plume had no northerly component of motion. The plume also did not show any flow toward the front, suggesting a balance between the northerly component of wind stress and the southerly component of buoyant spreading. In addition, the motion of the plume did not appear to affect the motion of the underlying ambient water, suggesting a lack of mixing between the two waters. ?? 1993 Estuarine Research Federation.

  17. Early-stage hypogene karstification in a mountain hydrologic system: A coupled thermohydrochemical model incorporating buoyant convection

    NASA Astrophysics Data System (ADS)

    Chaudhuri, A.; Rajaram, H.; Viswanathan, H.

    2013-09-01

    The early stage of hypogene karstification is investigated using a coupled thermohydrochemical model of a mountain hydrologic system, in which water enters along a water table and descends to significant depth (˜1 km) before ascending through a central high-permeability fracture. The model incorporates reactive alteration driven by dissolution/precipitation of limestone in a carbonic acid system, due to both temperature- and pressure-dependent solubility, and kinetics. Simulations were carried out for homogeneous and heterogeneous initial fracture aperture fields, using the FEHM (Finite Element Heat and Mass Transfer) code. Initially, retrograde solubility is the dominant mechanism of fracture aperture growth. As the fracture transmissivity increases, a critical Rayleigh number value is exceeded at some stage. Buoyant convection is then initiated and controls the evolution of the system thereafter. For an initially homogeneous fracture aperture field, deep well-organized buoyant convection rolls form. For initially heterogeneous aperture fields, preferential flow suppresses large buoyant convection rolls, although a large number of smaller rolls form. Even after the onset of buoyant convection, dissolution in the fracture is sustained along upward flow paths by retrograde solubility and by additional "mixing corrosion" effects closer to the surface. Aperture growth patterns in the fracture are very different from those observed in simulations of epigenic karst systems, and retain imprints of both buoyant convection and preferential flow. Both retrograde solubility and buoyant convection contribute to these differences. The paper demonstrates the potential value of coupled models as tools for understanding the evolution and behavior of hypogene karst systems.

  18. An improved genetic system for bioengineering buoyant gas vesicle nanoparticles from Haloarchaea

    PubMed Central

    2013-01-01

    Background Gas vesicles are hollow, buoyant organelles bounded by a thin and extremely stable protein membrane. They are coded by a cluster of gvp genes in the halophilic archaeon, Halobacterium sp. NRC-1. Using an expression vector containing the entire gvp gene cluster, gas vesicle nanoparticles (GVNPs) have been successfully bioengineered for antigen display by constructing gene fusions between the gvpC gene and coding sequences from bacterial and viral pathogens. Results To improve and streamline the genetic system for bioengineering of GVNPs, we first constructed a strain of Halobacterium sp. NRC-1 deleted solely for the gvpC gene. The deleted strain contained smaller, more spindle-shaped nanoparticles observable by transmission electron microscopy, confirming a shape-determining role for GvpC in gas vesicle biogenesis. Next, we constructed expression plasmids containing N-terminal coding portions or the complete gvpC gene. After introducing the expression plasmids into the Halobacterium sp. NRC-1 ΔgvpC strain, GvpC protein and variants were localized to the GVNPs by Western blotting analysis and their effects on increasing the size and shape of nanoparticles established by electron microscopy. Finally, a synthetic gene coding for Gaussia princeps luciferase was fused to the gvpC gene fragments on expression plasmids, resulting in an enzymatically active GvpC-luciferase fusion protein bound to the buoyant nanoparticles from Halobacterium. Conclusion GvpC protein and its N-terminal fragments expressed from plasmid constructs complemented a Halobacterium sp. NRC-1 ΔgvpC strain and bound to buoyant GVNPs. Fusion of the luciferase reporter gene from Gaussia princeps to the gvpC gene derivatives in expression plasmids produced GVNPs with enzymatically active luciferase bound. These results establish a significantly improved genetic system for displaying foreign proteins on Halobacterium gas vesicles and extend the bioengineering potential of these novel

  19. Large Eddy Simulation of a Forced Round Turbulent Buoyant Plume in Neutral Surroundings

    NASA Technical Reports Server (NTRS)

    Basu, A. J.; Mansour, N. N.; Koga, Dennis (Technical Monitor)

    1999-01-01

    Buoyant flows play an important role in various technological and environmental issues. For example, dispersal of pollutants, smoke, or volcano exhaust in the atmosphere, vertical motion of air, formation of clouds and other weather systems, and flows in cooling towers and fires are all determined primarily by buoyancy effects. The buoyancy force in such flows can originate from either a heat source or due to different densities between a fluid and its surroundings. Whatever the cause, the flow can be understood by studying the effects of the tight coupling between the thermal and the velocity fields since density differences can be characterized as temperature differences.

  20. What Is the Buoyant Force on a Block at the Bottom of a Beaker of Water?

    DTIC Science & Technology

    2006-01-01

    Bierman and E. Kincanon, “Reconsidering Archimedes ’ principle ,” Phys. Teach. 41, 340-344 (2003). [2] B.M. Valiyov and V.D. Yegorenkov, “Do fluids...always push up objects immersed in them?” Phys. Educ. 35, 284-286 (2000). [3] E.H. Graf, “Just what did Archimedes say about buoyancy?” Phys. Teach...elevator accelerating downward, the weight of and buoyant force on a submerged object are decreased. [7] J. Harper, “ Archimedes ’ principle and the FCI

  1. Scaling Analysis of Temperature Variability Between a Rotating Cylinder and a Turbulent Buoyant Jet

    NASA Astrophysics Data System (ADS)

    Lapointe, Caelan; Wimer, Nicholas T.; Hayden, Torrey R. S.; Christopher, Jason D.; Rieker, Gregory B.; Hamlington, Peter E.

    2016-11-01

    Vortex shedding from a cylinder is a canonical problem in fluid dynamics and is a phenomenon whose behavior is well documented for a wide range of Reynolds numbers. Industrial processes, by contrast, often have many moving parts that may also be exposed to high temperatures, resulting in highly complex flow fields. This complexity can, in turn, introduce velocity and temperature variations that may be undesirable for a particular industrial process. In this study, we specifically seek to understand and parameterize temperature variability between a rotating cylinder and a high-temperature turbulent buoyant jet. The relevance of this configuration for industrial processing is outlined, and velocity and temperature fields between the jet and cylinder are obtained using large eddy simulations (LES). In the LES, key parameters such as the angular velocity and diameter of the cylinder, the dimensions, velocity, and temperature of the turbulent buoyant jet, and the distance between the cylinder and the jet are varied. The resulting LES results are then used to develop scaling relationships between temperature variance near the cylinder and other problem parameters. Such scaling relations will be highly beneficial for the estimation of temperature variations in industrial applications.

  2. Supergranulation as the Largest Buoyantly Driven Convective Scale of the Sun

    NASA Astrophysics Data System (ADS)

    Cossette, Jean-Francois; Rast, Mark P.

    2016-09-01

    The origin of solar supergranulation remains a mystery. Unlike granulation, the size of which is comparable to both the thickness of the radiative boundary layer and local scale-height in the photosphere, supergranulation does not reflect any obvious length scale of the solar convection zone. Moreover, recent observations of flows in the photosphere using Doppler imaging or correlation or feature tracking show a monotonic decrease in horizontal flow power at scales larger than supergranulation. Both local area and global spherical shell simulations of solar convection by contrast show the opposite, an increase in horizontal flow amplitudes to a low wavenumber. We examine these disparities and investigate how the solar supergranulation may arise as a consequence of nonlocal heat transport by cool diving plumes. Using three-dimensional anelastic simulations with surface driving, we show that the kinetic energy of the largest convective scales in the upper layers of a stratified domain reflects the depth of transition from strong buoyant driving to adiabatic stratification below caused by the dilution of the granular downflows. This depth is quite shallow because of the rapid increase of the mean density below the photosphere. We interpret the observed monotonic decrease in solar convective power at scales larger than supergranulation to be a consequence of this rapid transition, with the supergranular scale the largest buoyantly driven mode of convection in the Sun.

  3. Characterization of Buoyant Fluorescent Particles for Field Observations of Water Flows

    PubMed Central

    Tauro, Flavia; Aureli, Matteo; Porfiri, Maurizio; Grimaldi, Salvatore

    2010-01-01

    In this paper, the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows is investigated. Microspheres’ fluorescence intensity is experimentally measured and detected in placid aqueous suspensions of increasing concentrations of clay to simulate typical conditions occurring in natural drainage networks. Experiments are conducted in a broad range of clay concentrations and particle immersion depths by using photoconductive cells and image-based sensing technologies. Results obtained with both methodologies exhibit comparable trends and show that the considered particles are fairly detectable in critically turbid water flows. Further information on performance and integration of the studied microspheres in low-cost measurement instrumentation for field observations is obtained through experiments conducted in a custom built miniature water channel. This experimental characterization provides a first assessment of the feasibility of commercially available buoyant fluorescent beads in the analysis of high turbidity surface water flows. The proposed technology may serve as a minimally invasive sensing system for hazardous events, such as pollutant diffusion in natural streams and flash flooding due to extreme rainfall. PMID:22163540

  4. Effects of inertia and turbulence on rheological measurements of neutrally buoyant suspensions

    NASA Astrophysics Data System (ADS)

    Linares-Guerrero, Esperanza; Hunt, Melany L.; Zenit, Roberto

    2017-01-01

    For low-Reynolds number shear-flows of neutrally-buoyant suspensions, the shear stress is often modeled using an effective viscosity that depends only on the solid fraction. As the Reynolds number ($Re$) is increased and inertia becomes important, the effective viscosity also depends on the Reynolds number itself. The current experiments measure the torque for flows of neutrally-buoyant particles in a coaxial-cylinder rheometer for solid fractions, $\\phi$, from 10\\% to 50\\% and Reynolds numbers based on particle diameter from 2 to 1,000. For experiments for Reynolds of O(10) and solid fractions less than $30\\%$, the effective viscosity increases with Reynolds number, in good agreement with recent numerical simulations found in the literature. At higher solid fractions over the same range of $Re$, the results show a decrease in torque with shear rate. For Reynolds numbers greater than 100 and lower solids concentrations, the effective viscosity continues to increase with Reynolds number. However, based on comparisons with pure fluid measurements the increase in the measured effective viscosity results from the transition to turbulence. The particles augment the turbulence by increasing the magnitude of the measured torques and causing the flow to transition at lower Reynolds numbers. For the highest solid fractions, the measurements show a significant increase in the magnitude of the torques, but the effective viscosity is independent of Reynolds number.

  5. Video Image Analysis of Turbulent Buoyant Jets Using a Novel Laboratory Apparatus

    NASA Astrophysics Data System (ADS)

    Crone, T. J.; Colgan, R. E.; Ferencevych, P. G.

    2012-12-01

    Turbulent buoyant jets play an important role in the transport of heat and mass in a variety of environmental settings on Earth. Naturally occurring examples include the discharges from high-temperature seafloor hydrothermal vents and from some types of subaerial volcanic eruptions. Anthropogenic examples include flows from industrial smokestacks and the flow from the damaged well after the Deepwater Horizon oil leak of 2010. Motivated by a desire to find non-invasive methods for measuring the volumetric flow rates of turbulent buoyant jets, we have constructed a laboratory apparatus that can generate these types of flows with easily adjustable nozzle velocities and fluid densities. The jet fluid comprises a variable mixture of nitrogen and carbon dioxide gas, which can be injected at any angle with respect to the vertical into the quiescent surrounding air. To make the flow visible we seed the jet fluid with a water fog generated by an array of piezoelectric diaphragms oscillating at ultrasonic frequencies. The system can generate jets that have initial densities ranging from approximately 2-48% greater than the ambient air. We obtain independent estimates of the volumetric flow rates using well-calibrated rotameters, and collect video image sequences for analysis at frame rates up to 120 frames per second using a machine vision camera. We are using this apparatus to investigate several outstanding problems related to the physics of these flows and their analysis using video imagery. First, we are working to better constrain several theoretical parameters that describe the trajectory of these flows when their initial velocities are not parallel to the buoyancy force. The ultimate goal of this effort is to develop well-calibrated methods for establishing volumetric flow rates using trajectory analysis. Second, we are working to refine optical plume velocimetry (OPV), a non-invasive technique for estimating flow rates using temporal cross-correlation of image

  6. Buoyant thermal plumes from planetary landers and rovers: Application to sizing of meteorological masts

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Sotzen, Kristin S.

    2014-01-01

    Objective. Landers on Mars and Titan may have warm surfaces as a result of solar heating or the carriage of radioisotope power sources. This warmth can perturb downwind meteorological measurements, but cannot be modeled as a simple aerodynamic wake because buoyant forces can be significant. Methods. We use an analytic model from the industrial aerodynamics literature on smoke dispersion from fires and smokestacks to evaluate the plume trajectories. Computational Fluid Dynamics (CFD) simulations are also performed for a Titan lander. Results. CFD yields results similar to the analytic model. (Albeit with a possibly weaker dependence on windspeed than the classic model.) We apply the models to evaluate the probability of immersion of instrumentation in plumes from the Mars Science Laboratory (MSL) Curiosity and for a Titan lander under various wind scenarios. Conclusions. Lander perturbations can be easily calculated. Practice implications. None.

  7. Tomography reveals buoyant asthenosphere accumulating beneath the Juan de Fuca plate

    NASA Astrophysics Data System (ADS)

    Hawley, William B.; Allen, Richard M.; Richards, Mark A.

    2016-09-01

    The boundary between Earth’s strong lithospheric plates and the underlying mantle asthenosphere corresponds to an abrupt seismic velocity decrease and electrical conductivity increase with depth, perhaps indicating a thin, weak layer that may strongly influence plate motion dynamics. The behavior of such a layer at subduction zones remains unexplored. We present a tomographic model, derived from on- and offshore seismic experiments, that reveals a strong low-velocity feature beneath the subducting Juan de Fuca slab along the entire Cascadia subduction zone. Through simple geodynamic arguments, we propose that this low-velocity feature is the accumulation of material from a thin, weak, buoyant layer present beneath the entire oceanic lithosphere. The presence of this feature could have major implications for our understanding of the asthenosphere and subduction zone dynamics.

  8. On the Interaction of Buoyant Plumes With Ocean Mixed-Layer Fronts (Invited)

    NASA Astrophysics Data System (ADS)

    Ozgokmen, T. M.; Fischer, P. F.

    2010-12-01

    The ocean's surface mixed layer is notoriously complex due to high spatial and temporal gradients of density and velocity fields. The understanding and modeling of such flows have a wide range of applications. For instance, anomalous currents and density perturbations in the acoustic and optical environment can affect a variety of naval operations. These flows can also influence strongly the dispersion of surface and sub-surface pollutants. Large eddy simulations of an idealized mixed-layer problem are conducted using a non-hydrostatic spectral element model. Sampling strategies of these fields are investigated using passive tracers and Lagrangian particles. These idealized fields are then used in order to explore the behavior of a buoyant plume through the water column, namely its surface and sub-surface dispersion, which is motivated by the Deepwater Horizon oil spill.

  9. On the Interaction of Buoyant Plumes With Ocean Mixed-Layer Fronts

    NASA Astrophysics Data System (ADS)

    Özgökmen, Tamay

    2010-11-01

    The ocean's surface mixed layer is notoriously complex due to high spatial and temporal gradients of density and velocity fields. The understanding and modeling of such flows have a wide range of applications. For instance, anomalous currents and density perturbations in the acoustic and optical environment can affect a variety of naval operations. These flows can also influence strongly the dispersion of surface and sub-surface pollutants. Large eddy simulations of an idealized mixed-layer problem are conducted using the spectral element model Nek5000. Sampling strategies of these fields are investigated using passive tracers and Lagrangian particles. These idealized fields are then used in order to explore the behavior of a buoyant plume through the water column, namely its surface and sub-surface dispersion, which is motivated by the Deepwater Horizon oil spill.

  10. Wind and tidal forcing of a buoyant plume, Mobile Bay, Alabama

    USGS Publications Warehouse

    Stumpf, R.P.; Gelfenbaum, G.; Pennock, J.R.

    1993-01-01

    AVHRR satellite imagery and in situ observations were combined to study the motion of a buoyant plume at the mouth of Mobile Bay, Alabama. The plume extended up to 30 km from shore, with a thickness of about 1 m. The inner plume, which was 3-8 m thick, moved between the Bay and inner shelf in response to tidal forcing. The tidal prism could be identified through the movement of plume waters between satellite images. The plume responded rapidly to alongshore wind, with sections of the plume moving at speeds of more than 70 cm s-1, about 11% of the wind speed. The plume moved predominantly in the direction of the wind with a weak Ekman drift. The enhanced speed of the plume relative to normal surface drift is probably due to the strong stratification in the plume, which limits the transfer of momentum into the underlying ambient waters. ?? 1993.

  11. Long-term tracking of neutrally buoyant tracer particles in two-dimensional fluid flows

    NASA Astrophysics Data System (ADS)

    Pervez, M. S.; Solomon, T. H.

    1994-07-01

    An experimental technique has been developed to produce and to track neutrally buoyant particles in a two-dimensional fluid flow. The key aspect of the technique is the ability to track particles for extended intervals (over an hour), which is essential for quantitative studies of transport and mixing. The approach is composed of two stages. In the first stage, digital image processing hardware partially processes the images, reducing the data rate to 50 kbyte/s (typically) and allowing several hours of data to be stored on a conventional computer disk. In the second stage, programs extract particle trajectories from the reduced data. The approach is tested in an experiment on planetary-type flows in a rotating annulus. In an appendix, a technique is discussed for fabricating wax or crayon particles with arbitrary density.

  12. Tomography reveals buoyant asthenosphere accumulating beneath the Juan de Fuca plate.

    PubMed

    Hawley, William B; Allen, Richard M; Richards, Mark A

    2016-09-23

    The boundary between Earth's strong lithospheric plates and the underlying mantle asthenosphere corresponds to an abrupt seismic velocity decrease and electrical conductivity increase with depth, perhaps indicating a thin, weak layer that may strongly influence plate motion dynamics. The behavior of such a layer at subduction zones remains unexplored. We present a tomographic model, derived from on- and offshore seismic experiments, that reveals a strong low-velocity feature beneath the subducting Juan de Fuca slab along the entire Cascadia subduction zone. Through simple geodynamic arguments, we propose that this low-velocity feature is the accumulation of material from a thin, weak, buoyant layer present beneath the entire oceanic lithosphere. The presence of this feature could have major implications for our understanding of the asthenosphere and subduction zone dynamics.

  13. Buoyant Effects on the Flammability of Silicone Samples Planned for the Spacecraft Fire Experiment (Saffire)

    NASA Technical Reports Server (NTRS)

    Niehaus, Justin E.; Ferkul, Paul V.; Gokoglu, Suleyman A.; Ruff, Gary A.

    2015-01-01

    Flammability experiments on silicone samples were conducted in anticipation of the Spacecraft Fire Experiment (Saffire). The sample geometry was chosen to match the NASA 6001 Test 1 specification, namely 5 cm wide by 30 cm tall. Four thicknesses of silicone (0.25, 0.36, 0.61 and 1.00 mm) were examined. Tests included traditional upward buoyant flame spread using Test 1 procedures, downward opposed-flow flame spread, horizontal and angled flame spread, and forced-flow upward and downward flame spread. In addition to these configurations, upward and downward tests were conducted in a chamber with varying oxygen concentrations. In the upward buoyant flame spread tests, the flame generally did not burn the entire sample. As thickness was increased, the flame spread distance decreased before flame extinguishment. For the thickest sample, ignition could not be achieved. In the downward tests, the two thinnest samples permitted the flame to burn the entire sample, but the spread rate was lower compared to the corresponding upward values. The other two thicknesses could not be ignited in the downward configuration. The increased flammability for downward spreading flames relative to upward ones is uncommon. The two thinnest samples also burned completely in the horizontal configuration, as well as at angles up to 75 degrees from the horizontal. Upward tests in air with an added forced flow were more flammable. The upward and downward flammability behavior was compared in atmospheres of varying oxygen concentration to determine a maximum oxygen concentration for each configuration. Complementary analyses using EDS, TGA, and SEM techniques suggest the importance of the silica layer deposited downstream onto the unburned sample surface.

  14. Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

    PubMed Central

    Liu, Jiaping; Wang, Hai; Liu, Qiuhan

    2013-01-01

    The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa. PMID:24000278

  15. Flow-field characteristics of high-temperature annular buoyant jets and their development laws influenced by ventilation system.

    PubMed

    Wang, Yi; Huang, Yanqiu; Liu, Jiaping; Wang, Hai; Liu, Qiuhan

    2013-01-01

    The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to -5 Pa.

  16. The spatial distribution and speciation of iron in buoyant hydrothermal plumes of the Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Cron, B. R.; Toner, B. M.; Bennett, S. A.; German, C. R.; Dick, G.; Breier, J. A.

    2012-12-01

    Biogeochemical cycling of elements, such as iron and sulfur, at mid-ocean ridge spreading centers may modulate hydrothermal fluxes to the ocean. To better understand the nature and scale of these processes, the geochemical gradients in buoyant plumes were examined at the Mid-Cayman Rise, a short (~110 km) ultra-slow spreading center in the Caribbean Sea that hosts the deepest known high temperature venting. Changes in particulate iron and sulfur speciation were measured in the first 40-50 m of buoyant plumes at two vent fields, Von Damm (2,300m) and Piccard (5,000m). These data will be used to identify products of precipitation reactions and define particulate energy sources available for microbial metabolism. A series of samples were collected by in situ filtration at 0.5 m and 50 m above the Beebe Vents, Piccard hydrothermal field and at 1 m, 8 m, and 40 m above the central spire of the Von Damm vent field using the ROV Jason and CTD-casts. Samples were packaged under dinitrogen and frozen shipboard to preserve oxidation-reduction sensitive species for microprobe Fe 1s and S 1s X-ray absorption near edge structure (XANES) spectroscopy (Advanced Light Source, Lawrence Berkeley National Laboratory, beamline 10.3.2). The Von Damm vent is characterized by shimmering vent fluids with dilute particulates in the buoyant plume. Within the particulate phase, the Von Damm buoyant plume was comprised of 38 mol % Fe-sulfides, 40 mol % Fe(II), and 21 mol % Fe(III) at 1 m. At 8 m it is comprised of 32 mol % Fe-sulfides, 7 % Fe(II), and 59 mol % Fe(III). When the plume reaches 40 m, it is 6 mol % Fe-sulfides, 8 mol % Fe(II), 72 mol % Fe(III), and 14 mol % Fe(0). The Beebe vents are characterized by very dense particle formation in their buoyant plumes. The Beebe vent plume sampled comprised 65 mol % sulfides, 3 % mol Fe(II) & 32 mol % Fe(III)¬¬¬¬ at 0.5 m. As the plume reached 50 m above the vent, the fluids were 43 mol % sulfide and 56 mol % Fe(III). Both buoyant plume

  17. Evolution of localized blobs of swirling or buoyant fluid with and without an ambient magnetic field

    NASA Astrophysics Data System (ADS)

    Davidson, P. A.; Sreenivasan, Binod; Aspden, A. J.

    2007-02-01

    We investigate the evolution of localized blobs of swirling or buoyant fluid in an infinite, inviscid, electrically conducting fluid. We consider the three cases of a strong imposed magnetic field, a weak imposed magnetic field, and no magnetic field. For a swirling blob in the absence of a magnetic field, we find, in line with others, that the blob bursts radially outward under the action of the centrifugal force, forming a thin annular vortex sheet. A simple model of this process predicts that the vortex sheet thins exponentially fast and that it moves radially outward with constant velocity. These predictions are verified by high-resolution numerical simulations. When an intense magnetic field is applied, this phenomenon is suppressed, with the energy and angular momentum of the blob now diffusing axially along the magnetic field lines, converting the blob into a columnar structure. For modest or weak magnetic fields, there are elements of both types of behavior, with the radial bursting dominating over axial diffusion for weak fields. However, even when the magnetic field is very weak, the flow structure is quite distinct to that of the nonmagnetic case. In particular, a small but finite magnetic field places a lower bound on the thickness of the annular vortex sheet and produces an annulus of counter-rotating fluid that surrounds the vortex core. The behavior of the buoyant blob is similar. In the absence of a magnetic field, it rapidly develops the mushroomlike shape of a thermal, with a thin vortex sheet at the top and sides of the mushroom. Again, a simple model of this process predicts that the vortex sheet at the top of the thermal thins exponentially fast and rises with constant velocity. These predictions are consistent with earlier numerical simulations. Curiously, however, it is shown that the net vertical momentum associated with the blob increases linearly in time, despite the fact that the vertical velocity at the front of the thermal is constant

  18. Evolution of localized blobs of swirling or buoyant fluid with and without an ambient magnetic field

    SciTech Connect

    Davidson, P. A.; Sreenivasan, Binod; Aspden, A. J.

    2007-02-15

    We investigate the evolution of localized blobs of swirling or buoyant fluid in an infinite, inviscid, electrically conducting fluid. We consider the three cases of a strong imposed magnetic field, a weak imposed magnetic field, and no magnetic field. For a swirling blob in the absence of a magnetic field, we find, in line with others, that the blob bursts radially outward under the action of the centrifugal force, forming a thin annular vortex sheet. A simple model of this process predicts that the vortex sheet thins exponentially fast and that it moves radially outward with constant velocity. These predictions are verified by high-resolution numerical simulations. When an intense magnetic field is applied, this phenomenon is suppressed, with the energy and angular momentum of the blob now diffusing axially along the magnetic field lines, converting the blob into a columnar structure. For modest or weak magnetic fields, there are elements of both types of behavior, with the radial bursting dominating over axial diffusion for weak fields. However, even when the magnetic field is very weak, the flow structure is quite distinct to that of the nonmagnetic case. In particular, a small but finite magnetic field places a lower bound on the thickness of the annular vortex sheet and produces an annulus of counter-rotating fluid that surrounds the vortex core. The behavior of the buoyant blob is similar. In the absence of a magnetic field, it rapidly develops the mushroomlike shape of a thermal, with a thin vortex sheet at the top and sides of the mushroom. Again, a simple model of this process predicts that the vortex sheet at the top of the thermal thins exponentially fast and rises with constant velocity. These predictions are consistent with earlier numerical simulations. Curiously, however, it is shown that the net vertical momentum associated with the blob increases linearly in time, despite the fact that the vertical velocity at the front of the thermal is constant

  19. Dispersal of volcaniclasts during deep-sea eruptions: Settling velocities and entrainment in buoyant seawater plumes

    NASA Astrophysics Data System (ADS)

    Barreyre, Thibaut; Soule, S. Adam; Sohn, Robert A.

    2011-08-01

    We use tank experiments to measure settling rates of deep-sea volcaniclastic material recovered from the Arctic (85°E Gakkel Ridge) and Pacific (Juan de Fuca Ridge, Loihi seamount) Oceans. We find that clast size and shape exert a strong influence on settling velocity, with velocities of ~ 30 cm/s for large (~ 8 mm), blocky clasts, compared to velocities of ~ 2.5 cm/s for small (< 0.5 mm), sheet-like clasts. We fit our observations to the generalized model of Ferguson and Church (2004) to establish empirical scaling laws for settling velocity, and then use these results to test the hypothesis that entrainment in a buoyant plume of hot seawater is an important dispersal mechanism for volcaniclastic material in the deep-sea (Clague et al., 2009). We superpose the observed settling rates on velocity fields generated with the Morton et al. (1956) model for turbulent plumes in stratified media to estimate the rise height of the clastic material under water column conditions corresponding to the Gakkel and Juan de Fuca (JdFR) Ridges, and then estimate dispersal distances assuming the grains settle to the seafloor while being advected in lateral currents. Dispersal distances in our model are a function plume strength (i.e., buoyancy flux), lateral current speeds, and clast settling velocity. Our model demonstrates that large (30 GW) eruption 'megaplumes' can loft volcaniclastic material more than a kilometer above the seafloor where entrainment in deep-sea currents can advect dominant clast types (~ 1 mm, blocky grains) up to a few hundred meters from a source vent. Small bubble-wall fragments (e.g., limu o Pele) entrained in a megaplume could be advected as far as a few kilometers from a source region. These results indicate that entrainment in buoyant seawater plumes during an eruption may play an important role in clast dispersal, but it is not clear if this mechanism can explain the distribution of volcaniclastic material at the sites on the Gakkel and Juan de Fuca

  20. Nonlinear adjustment of a localized layer of buoyant, uniform potential vorticity fluid against a vertical wall

    NASA Astrophysics Data System (ADS)

    Helfrich, Karl R.

    2006-08-01

    The nonlinear evolution of a localized layer of buoyant, uniform potential vorticity fluid with depth H, width w and length L released adjacent to a wall in a rotating system is studied using reduced-gravity shallow-water theory and numerical modeling. In the interior, far from the two ends of the layer, the initial adjustment gives, after ignoring inertia-gravity waves, a geostrophic flow of width w and layer velocities parallel to the wall directed in the downstream direction (defined by Kelvin wave propagation). This steady geostrophic flow serves as the initial condition for a semigeostrophic solution using the method of characteristics. At the downstream end, the theory shows that the fluid intrudes along the wall as rarefaction terminating at a nose of vanishing width and depth. However, in a real fluid the presence of the lower layer leads to a blunt gravity current head. The theory is amended by introducing a gravity current head condition that has a blunt bore joined to the rarefaction by a uniform gravity current. The upstream termination of the initial layer produces a Kelvin rarefaction that propagates downstream, decreasing the layer depth along the wall, and initiating upstream flow adjacent to the wall. The theoretical solution compares favorably to numerical solutions of the reduced-gravity shallow-water equations. The agreement between theory and numerical solutions occurs regardless of whether the numerical runs are initiated with an adjusted geostrophic solution or with the release of a stagnant layer. The latter case excites inertia-gravity waves that, despite their large amplitude and breaking, do not significantly affect the evolution of the geostrophic flow. At times beyond the validity of the semigeostrophic theory, the numerical solutions evolve into a stationary array of vortices. The vortex formation can be interpreted as the finite-amplitude manifestation of a linear instability of the new flow established by the passage of the Kelvin

  1. Buoyant Effects on the Flammability of Silicone Samples Planned for the Spacecraft Fire Experiment (Saffire)

    NASA Technical Reports Server (NTRS)

    Niehaus, Justin; Ferkul, Paul V.; Gokoglu, Suleyman; Ruff, Gary

    2015-01-01

    Flammability experiments on silicone samples were conducted in anticipation of the Spacecraft Fire Experiment (Saffire). The sample geometry was chosen to match the NASA 6001 Test 1 specification, namely 5 cm wide by 30 cm tall. Four thicknesses of silicone (0.25, 0.36, 0.61 and 1.00 mm) were examined. Tests included traditional upward buoyant flame spread using Test 1 procedures, downward opposed flow flame spread, horizontal and angled flame spread, forced flow upward and downward flame spread. In addition to these configurations, upward and downward tests were also conducted in a chamber with varying oxygen concentrations. In the upward buoyant flame spread tests, the flame generally did not burn the entire sample. As thickness was increased, the flame spread distance decreased before flame extinguishment. For the thickest sample, ignition could not be achieved. In the downward tests, the two thinnest samples permitted the flame to burn the entire sample, but the spread rate was lower compared to the corresponding upward values. The other two thicknesses could not be ignited in the downward configuration. The increased flammability for downward spreading flames relative to upward ones is uncommon. The two thinnest samples also burned completely in the horizontal configuration, as well as at angles up to 75 degrees from the horizontal. The upward and downward flammability behavior was compared in atmospheres of varying oxygen concentration to determine a maximum oxygen concentration for each configuration. Upward tests in air with an added forced flow were more flammable. Complementary analyses using SEM and TGA techniques suggest the importance of the silica layer formed on the burned sample surface. As silicone burns upward, silica deposits downstream •If the silicone is ignited in the downward configuration, it burns the entire length of the sample •Burning upward at an angle increases the burn length in some cases possibly due to less silica deposition

  2. Wave induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    NASA Astrophysics Data System (ADS)

    Drivdal, M.; Broström, G.; Christensen, K. H.

    2014-05-01

    The modelling of wave-current and wave-turbulence interactions have received much attention in recent years. In this study the focus is on how these wave effects modify the transport of particles in the ocean. Here the particles are buoyant tracers that can represent oil droplets, plastic particles or plankton, for example fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM), modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production as well as the stronger veering by the Coriolis-Stokes force affect the drift of the particles. The energy and momentum fluxes as well as the Stokes drift depend on the directional wave spectrum that can be obtained from a wave model or from observations. As a first test the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (e.g. classical Ekman theory). Secondly the model is applied to a case where we investigate the oil drift after an offshore oil spill outside the western coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by empirical models. With wind and wave forcing from the ERA Interim archive, it is shown that the wave effects are important for the resultant drift in this case, and has the potential to improve drift forecasting.

  3. Wave-induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    NASA Astrophysics Data System (ADS)

    Drivdal, M.; Broström, G.; Christensen, K. H.

    2014-12-01

    This study focuses on how wave-current and wave-turbulence interactions modify the transport of buoyant particles in the ocean. Here the particles can represent oil droplets, plastic particles, or plankton such as fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM), modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production, as well as the stronger veering by the Coriolis-Stokes force, affects the drift of the particles. The energy and momentum fluxes, as well as the Stokes drift, depend on the directional wave spectrum obtained from a wave model. As a first test, the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (i.e., classical Ekman theory). Secondly, the model is applied to a case in which we investigate the oil drift after an oil spill off the west coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by oil-drift models. In this case, using wind and wave forcing from the ERA Interim archive it is shown that the wave effects are important for the resultant drift and have the potential to improve drift forecasting.

  4. Cascadia Initiative Reveals Accumulation of Buoyant Material Beneath the Subducting Juan de Fuca Plate

    NASA Astrophysics Data System (ADS)

    Hawley, W. B.; Allen, R. M.; Richards, M. A.

    2015-12-01

    The Cascadia Initiative is a four-year (2011-2015) amphibious seismic deployment that covers the Juan de Fuca plate and the Cascadia Subduction Zone. It is comprised of 70 broadband ocean-bottom seismometers that occupy 120 sites in total, as well as 27 land-based stations. This array offers a unique opportunity to study the 3D structure of a subduction zone in unprecedented detail. We present the results of an inversion using teleseismic body waves recorded by the Cascadia Initiative, EarthScope, and other regional and temporary networks in the Pacific Northwest. A low-velocity feature is visible beneath the subducting slab at shallow depths. Previous studies report ponding of low-viscosity, buoyant material at the top of the asthenosphere, unable to rise through the impermeable lithospheric lid. We show that as the lithospheric lid descends into the mantle, this material is not advected with it; rather, due to its own weakness and buoyancy, it accumulates at the subduction zone. Such material could be partly responsible for the rapid uplift and volcanism in the Coast Range of California, in the wake of the northward migration of the Mendocino Triple Junction. This newly observed feature may play an important role in the structure of subduction zones, but understanding the extent of that role on a global scale will require amphibious seismic deployments in other subduction zones.

  5. Numerical simulation of 2D buoyant jets in ice-covered and temperature-stratified water

    NASA Astrophysics Data System (ADS)

    Gu, Ruochuan

    A two-dimensional (2D) unsteady simulation model is applied to the problem of a submerged warm water discharge into a stratified lake or reservoir with an ice cover. Numerical simulations and analyses are conducted to gain insight into large-scale convective recirculation and flow processes in a cold waterbody induced by a buoyant jet. Jet behaviors under various discharge temperatures are captured by directly modeling flow and thermal fields. Flow structures and processes are described by the simulated spatial and temporal distributions of velocity and temperature in various regions: deflection, recirculation, attachment, and impingement. Some peculiar hydrothermal and dynamic features, e.g. reversal of buoyancy due to the dilution of a warm jet by entraining cold ambient water, are identified and examined. Simulation results show that buoyancy is the most important factor controlling jet behavior and mixing processes. The inflow boundary is treated as a liquid wall from which the jet is offset. Similarity and difference in effects of boundaries perpendicular and parallel to flow, and of buoyancy on jet attachment and impingement, are discussed. Symmetric flow configuration is used to de-emphasize the Coanda effect caused by offset.

  6. Buoyant Filter Bio-Reactor (BFBR)--a novel anaerobic wastewater treatment unit.

    PubMed

    Panicker, Soosan J; Philipose, M C; Haridas, Ajit

    2008-01-01

    The Buoyant Filter Bio-Reactor (BFBR) is a novel and very efficient method for the treatment of complex wastewater. Sewage is a complex wastewater containing insoluble COD contributed by fat and proteins. The fat and proteins present in the domestic sewage cause operational problems and underperformance in the Upflow Anaerobic Sludge Blanket Reactor, used now for treating sewage anaerobically. The biogas yield from the BFBR is 0.36 m3/kg COD reduced and the methane content was about 70-80%. Production of methane by anaerobic digestion of organic waste had the benefit of lower energy costs for treatment and is thus environmentally beneficial to the society by providing a clean fuel from renewable feed stocks. The BFBR achieved a COD removal efficiency of 80-90% for an organic loading rate of 4.5 kg/m3/d at a hydraulic retention time of 3.25 hours. The effluent COD was less than 100 mg/l, thus saving on secondary treatment cost. No pretreatment like sedimentation was required for the influent to the BFBR. The BFBR can produce low turbidity effluent as in the activated sludge process (ASP). The land area required for the BFBR treatment plant is less when compared to ASP plant. Hence the problem of scarcity of land for the treatment plant is reduced. The total expenditure for erecting the unit was less than 50% as that of conventional ASP for the same COD removal efficiency including land cost.

  7. Inertial modes of a periodically forced buoyant drop attached to a capillary

    NASA Astrophysics Data System (ADS)

    Chebel, Nicolas Abi; Risso, Frédéric; Masbernat, Olivier

    2011-10-01

    A drop of heptane attached to a capillary tip immersed in water is submitted to small amplitude volume oscillations. Its interface is imaged by means of a high-speed camera and its shape decomposed into spherical harmonics. The forcing frequency is varied over a large range including the frequencies of resonance of the three first modes of inertial shape oscillations. For a small drop, which remains almost spherical at rest, the geometrical constraint imposed by the attachment on the capillary tip causes the oscillation modes to be very different from those of a free drop. Surprisingly, the resonance of large drops is observed at the frequency predicted for a free, pure, and neutrally buoyant drop and mainly involves a single spherical harmonic; only the damping rate is observed to be moderately larger. Since it gives rise to oscillations close to this ideal case, the present experimental method could be used, complementary to quasi-static oscillation of a pendant drop, to investigate dynamic interfacial tension at high frequency of various fluid systems.

  8. Buoyant-thermocapillary instabilities in extended liquid layers subjected to a horizontal temperature gradient

    NASA Astrophysics Data System (ADS)

    Burguete, J.; Mukolobwiez, N.; Daviaud, F.; Garnier, N.; Chiffaudel, A.

    2001-10-01

    We report experiments on buoyant-thermocapillary instabilities in differentially heated liquid layers. The results are obtained for a fluid of Prandtl number 10 in a rectangular geometry with different aspect ratios. Depending on the height of liquid and on the aspect ratios, the two-dimensional basic flow destabilizes into oblique traveling waves or longitudinal stationary rolls, respectively, for small and large fluid heights. Temperature measurements and space-time recordings reveal the waves to correspond to the hydrothermal waves predicted by the linear stability analysis of Smith and Davis [J. Fluid Mech. 132, 119 (1983)]. Moreover, the transition between traveling and stationary modes agrees with the work by Mercier and Normand [Phys. Fluids 8, 1433 (1996)] even if the exact characteristics of longitudinal rolls differ from theoretical predictions. A discussion about the relevant nondimensional parameters is included. In the stability domain of the waves, two types of sources have been evidenced. For larger heights, the source is a line and generally evolves towards one end of the container leaving a single wave whereas for smaller heights, the source looks like a point and emits a circular wave which becomes almost planar farther from the source in both directions.

  9. Near Surface Vapor Bubble Layers in Buoyant Low Stretch Burning of Polymethylmethacrylate

    NASA Technical Reports Server (NTRS)

    Olson, Sandra L.; Tien, J. S.

    1999-01-01

    Large-scale buoyant low stretch stagnation point diffusion flames over solid fuel (polymethylmethacrylate) were studied for a range of aerodynamic stretch rates of 2-12/ sec which are of the same order as spacecraft ventilation-induced stretch in a microgravity environment. An extensive layer of polymer material above the glass transition temperature is observed. Unique phenomena associated with this extensive glass layer included substantial swelling of the burning surface, in-depth bubble formation, and migration and/or elongation of the bubbles normal to the hot surface. The bubble layer acted to insulate the polymer surface by reducing the effective conductivity of the solid. The reduced in-depth conduction stabilized the flame for longer than expected from theory neglecting the bubble layer. While buoyancy acts to move the bubbles deeper into the molten polymer, thermocapillary forces and surface regression both act to bring the bubbles to the burning surface. Bubble layers may thus be very important in low gravity (low stretch) burning of materials. As bubbles reached the burning surface, monomer fuel vapors jetted from the surface, enhancing burning by entraining ambient air flow. Popping of these bubbles at the surface can expel burning droplets of the molten material, which may increase the fire propagation hazards at low stretch rates.

  10. Buoyant balaenids: the ups and downs of buoyancy in right whales.

    PubMed

    Nowacek, D P; Johnson, M P; Tyack, P L; Shorter, K A; McLellan, W A; Pabst, D A

    2001-09-07

    A variety of marine mammal species have been shown to conserve energy by using negative buoyancy to power prolonged descent glides during dives. A new non-invasive tag attached to North Atlantic right whales recorded swim stroke from changes in pitch angle derived from a three-axis accelerometer. These results show that right whales are positively buoyant near the surface, a finding that has significant implications for both energetics and management. Some of the most powerful fluke strokes observed in tagged right whales occur as they counteract this buoyancy as they start a dive. By contrast, right whales use positive buoyancy to power glides during ascent. Right whales appear to use their positive buoyancy for more efficient swimming and diving. However, this buoyancy may pose added risks of vessel collision. Such collisions are the primary source of anthropogenic mortality for North Atlantic right whales, whose population is critically endangered and declining. Buoyancy may impede diving responses to oncoming vessels and right whales may have a reduced ability to manoeuvre during free ascents. These risk factors can inform efforts to avoid collisions.

  11. Laser soot-scattering imaging of a large buoyant diffusion flame

    SciTech Connect

    Lye, R.C.M.; Toner, S.J.

    1987-01-01

    A novel diagnostic technique, which makes use of laser light scattered by soot particles, was used in an effort to identify the flame sheets within a natural gas diffusion flame. Soot particles, inherently created and consumed in the flame, were used as the scattering medium, which obviated the need for externally supplied seed material. Since no foreign material was added to the flame, the current technique can be considered truly nonintrusive. The soot distribution within a large buoyant natural gas diffusion flame is argued to be a reasonable marker of the flame sheets. Measurements made in 47.4-190 kW natural gas flames stabilized on a 0.5 m diameter burner show that the flame sheets are highly wrinkled and convoluted surfaces. The flame sheets are distributed fairly uniformly within the instantaneous volume of the flame, based on images of the associated soot, and the instantaneous flame volume is devoid of soot for 40-60% of the time. When soot is present, it is observed as thin sheets which become narrower in regions where the average strain rate is estimated to be greater.

  12. Turbulence Modeling Effects on the Prediction of Equilibrium States of Buoyant Shear Flows

    NASA Technical Reports Server (NTRS)

    Zhao, C. Y.; So, R. M. C.; Gatski, T. B.

    2001-01-01

    The effects of turbulence modeling on the prediction of equilibrium states of turbulent buoyant shear flows were investigated. The velocity field models used include a two-equation closure, a Reynolds-stress closure assuming two different pressure-strain models and three different dissipation rate tensor models. As for the thermal field closure models, two different pressure-scrambling models and nine different temperature variance dissipation rate, Epsilon(0) equations were considered. The emphasis of this paper is focused on the effects of the Epsilon(0)-equation, of the dissipation rate models, of the pressure-strain models and of the pressure-scrambling models on the prediction of the approach to equilibrium turbulence. Equilibrium turbulence is defined by the time rate (if change of the scaled Reynolds stress anisotropic tensor and heat flux vector becoming zero. These conditions lead to the equilibrium state parameters. Calculations show that the Epsilon(0)-equation has a significant effect on the prediction of the approach to equilibrium turbulence. For a particular Epsilon(0)-equation, all velocity closure models considered give an equilibrium state if anisotropic dissipation is accounted for in one form or another in the dissipation rate tensor or in the Epsilon(0)-equation. It is further found that the models considered for the pressure-strain tensor and the pressure-scrambling vector have little or no effect on the prediction of the approach to equilibrium turbulence.

  13. Wind relaxation and a coastal buoyant plume north of Pt. Conception, CA: Observations, simulations, and scalings

    NASA Astrophysics Data System (ADS)

    Suanda, Sutara H.; Kumar, Nirnimesh; Miller, Arthur J.; Di Lorenzo, Emanuele; Haas, Kevin; Cai, Donghua; Edwards, Christopher A.; Washburn, Libe; Fewings, Melanie R.; Torres, Rachel; Feddersen, Falk

    2016-10-01

    In upwelling regions, wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems. The coastal ocean response to wind relaxation around Pt. Conception, CA is simulated with a Regional Ocean Model (ROMS) forced by realistic surface and lateral boundary conditions including tidal processes. The model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner-shelf mooring locations throughout the study. A poleward-propagating plume of Southern California Bight water that increases shelf water temperatures by ≈ 5°C is also reproduced. Modeled plume propagation speed, spatial scales, and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface-trapped and slope-controlled dynamics. Plume momentum balances are distinct between the offshore (>30 m depth) region where the plume is surface-trapped, and onshore of the 30 m isobath (within 5 km from shore) where the plume water mass extends to the bottom and is slope controlled. In the onshore region, bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core. Numerical experiments without tidal forcing show that modeled surface temperatures are biased 0.5°C high, potentially affecting plume propagation distance and persistence.

  14. 3D Mixing Inside a Neutrally Buoyant Drop Driven by Electrohydrodynamic Flows

    NASA Astrophysics Data System (ADS)

    Xu, Xiumei; Homsy, G. M.

    2007-11-01

    For a neutrally buoyant drop subjected to a uniform electric field, the internal flow is the well-known Taylor circulation. In Phys. Fluids 19 013102 (2007), we theoretically studied three dimensional mixing by periodically switching a uniform electric field through an angle α. Periodically switching the field is equivalent to periodically changing the symmetry axis of the Taylor circulation. For α=0.5 π, there is no chaotic mixing because the common heteroclinic trajectories form the separatrix of the flow. For other switching angles, chaotic advection is generated due to perturbations of the heteroclinic trajectory. Experimental investigations of mixing were carried out using a nearly isopycnic silicone oil/castor oil system. For α=0.5 π, our experiments show the existence of symmetry planes. In addition, two blobs of particles are observed to maintain almost invariant shapes for very long time, indicating the absence of chaotic mixing, as predicted by the theory. For other switching angles, experiments show the penetration of symmetry planes by tracer particles. However it is difficult to draw definitive conclusions regarding chaotic mixing because of charge relaxation, long initial transients and drop translation effects.

  15. Performance and Seakeeping Tests and Analysis of a Structural Loads Model of a L/B=6 Buoyant Sidewall SES.

    DTIC Science & Technology

    1981-03-01

    higher hull -borne speeds Configur- ation 2 has about 15% more drag than Configuration 1; this might be corrected by optimizing the trim at high speed (30...cushion-borne operation is shown in the form of a drag coefficient over the speed range on Figure 14. This drag coefficient is based on a nominal...contemplated for the L/B=6 buoyant sidewall SES. The prediction of the long term maximum moment depends at least on a knowledge of the statistical

  16. Physiological Evaluation of A1 (Extreme-Cold-Weather) and A2 (Buoyant, Intermediate-Cold-Weather) Jackets.

    DTIC Science & Technology

    1983-08-01

    the resting metabolic heat will be dissipated through the clothing with the remaining 25% lost through the respiratory tract and insensible sweating...AD-A258 410 PHYSIOLOGICAL EVALUATION OF Al (EXTREME-COLD-WEATHER) AND A2 (BUOYANT, INTERMEDIATE-COLD-WEATHER) JACKETS NAVY CLOTHING AND TEXTILE...Navy Clothing and Textile Research Facility 523-003-30-06 21 Strathmore Road 523-003-30-08 Natick, MA 01760 11. CONTROLLING OFFICE NAME AND ADDRESS

  17. Design and evaluation of hydrophobic coated buoyant core as floating drug delivery system for sustained release of cisapride

    PubMed Central

    Jacob, Shery; Nair, Anroop B; Patil, Pandurang N

    2010-01-01

    An inert hydrophobic buoyant coated–core was developed as floating drug delivery system (FDDS) for sustained release of cisapride using direct compression technology. Core contained low density, porous ethyl cellulose, which was coated with an impermeable, insoluble hydrophobic coating polymer such as rosin. It was further seal coated with low viscosity hydroxypropyl methyl cellulose (HPMC E15) to minimize moisture permeation and better adhesion with an outer drug layer. It was found that stable buoyant core was sufficient to float the tablet more than 8 h without the aid of sodium bicarbonate and citric acid. Sustained release of cisapride was achieved with HPMC K4M in the outer drug layer. The floating lag time required for these novel FDDS was found to be zero, however it is likely that the porosity or density of the core is critical for floatability of these tablets. The in vitro release pattern of these tablets in simulated gastric fluid showed the constant and controlled release for prolonged time. It can be concluded that the hydrophobic coated buoyant core could be used as FDDS for gastroretentive delivery system of cisapride or other suitable drugs. PMID:24825997

  18. The Effects of Neutrally Buoyant, Externally Attached Transmitters on Swimming Performance and Predator Avoidance of Juvenile Chinook Salmon

    SciTech Connect

    Janak, Jill M.; Brown, Richard S.; Colotelo, Alison HA; Pflugrath, Brett D.; Stephenson, John R.; Deng, Zhiqun; Carlson, Thomas J.; Seaburg, Adam

    2012-08-01

    The presence of an externally attached telemetry tag is often associated with the potential for impaired swimming performance (i.e., snags and drag) as well as increased susceptibility to predation, specifically for smaller fish. The effects on swimming performance due to the presence of a neutrally buoyant externally attached acoustic transmitter were examined by comparing critical swimming speeds (Ucrit) for juvenile Chinook salmon tagged with two different neutrally buoyant external transmitters (Type A and B), nontagged individuals, and those surgically implanted with the current JSATS acoustic transmitter. Fish tagged with the Type A and B designs had lower Ucrit when compared to nontagged individuals. However, there was no difference in Ucrit among fish tagged with Type A or B designs compared to those with surgically implanted tags. Further testing was then conducted to determine if predator avoidance ability was affected due to the presence of Type A tags when compared to nontagged fish. No difference was detected in the number of tagged and nontagged fish consumed by rainbow trout throughout the predation trials. The results of this study support the further testing on the efficacy of a neutrally buoyant externally attached telemetry tag for survival studies involving juvenile salmonids passing through hydro turbines.

  19. Rise of Buoyant Emissions from Low-Level Sources in the Presence of Upstream and Downstream Obstacles

    NASA Astrophysics Data System (ADS)

    Pournazeri, Sam; Princevac, Marko; Venkatram, Akula

    2012-08-01

    Field and laboratory studies have been conducted to investigate the effect of surrounding buildings on the plume rise from low-level buoyant sources, such as distributed power generators. The field experiments were conducted in Palm Springs, California, USA in November 2010 and plume rise from a 9.3 m stack was measured. In addition to the field study, a laboratory study was conducted in a water channel to investigate the effects of surrounding buildings on plume rise under relatively high wind-speed conditions. Different building geometries and source conditions were tested. The experiments revealed that plume rise from low-level buoyant sources is highly affected by the complex flows induced by buildings stationed upstream and downstream of the source. The laboratory results were compared with predictions from a newly developed numerical plume-rise model. Using the flow measurements associated with each building configuration, the numerical model accurately predicted plume rise from low-level buoyant sources that are influenced by buildings. This numerical plume rise model can be used as a part of a computational fluid dynamics model.

  20. Genetic Affinities between Trans-Oceanic Populations of Non-Buoyant Macroalgae in the High Latitudes of the Southern Hemisphere

    PubMed Central

    Fraser, Ceridwen I.; Zuccarello, Giuseppe C.; Spencer, Hamish G.; Salvatore, Laura C.; Garcia, Gabriella R.; Waters, Jonathan M.

    2013-01-01

    Marine biologists and biogeographers have long been puzzled by apparently non-dispersive coastal taxa that nonetheless have extensive transoceanic distributions. We here carried out a broad-scale phylogeographic study to test whether two widespread Southern Hemisphere species of non-buoyant littoral macroalgae are capable of long-distance dispersal. Samples were collected from along the coasts of southern Chile, New Zealand and several subAntarctic islands, with the focus on high latitude populations in the path of the Antarctic Circumpolar Current or West Wind Drift. We targeted two widespread littoral macroalgal species: the brown alga Adenocystisutricularis (Ectocarpales, Heterokontophyta) and the red alga Bostrychiaintricata (Ceramiales, Rhodophyta). Phylogenetic analyses were performed using partial mitochondrial (COI), chloroplast (rbcL) and ribosomal nuclear (LSU / 28S) DNA sequence data. Numerous deeply-divergent clades were resolved across all markers in each of the target species, but close phylogenetic relationships – even shared haplotypes – were observed among some populations separated by large oceanic distances. Despite not being particularly buoyant, both Adenocystisutricularis and Bostrychiaintricata thus show genetic signatures of recent dispersal across vast oceanic distances, presumably by attachment to floating substrata such as wood or buoyant macroalgae. PMID:23894421

  1. Passive buoyant tracers in the ocean surface boundary layer: 2. Observations and simulations of microplastic marine debris

    NASA Astrophysics Data System (ADS)

    Brunner, K.; Kukulka, T.; Proskurowski, G.; Law, K. L.

    2015-11-01

    This paper is the second of a two-part series that investigates passive buoyant tracers in the ocean surface boundary layer (OSBL). The first part examines the influence of equilibrium wind-waves on vertical tracer distributions, based on large eddy simulations (LESs) of the wave-averaged Navier-Stokes equation. Motivated by observations of buoyant microplastic marine debris (MPMD), this study applies the LES model and the parametric one-dimensional column model from part one to examine the vertical distributions of MPMD. MPMD is widely distributed in vast regions of the subtropical gyres and has emerged as a major open ocean pollutant whose distribution is subject to upper ocean turbulence. The models capture shear-driven turbulence, Langmuir turbulence (LT), and enhanced turbulent kinetic energy input due to breaking waves (BWs). Model results are only consistent with observations of MPMD profiles and the relationship between surface concentrations and wind speed if LT effects are included. Neither BW nor shear-driven turbulence is capable of deeply submerging MPMD, suggesting that the observed vertical MPMD distributions are a characteristic signature of wave-driven LT. Thus, this study demonstrates that LT substantially increases turbulent transport in the OSBL, resulting in deep submergence of buoyant tracers. The parametric model is applied to 11 years of observations in the North Atlantic and North Pacific subtropical gyres to show that surface measurements substantially underestimate MPMD concentrations by a factor of 3-13.

  2. 46 CFR 160.060-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... closure for buoyant vests must— (1) Be tested for weathering. The Coast Guard will determine which one or...) for 24 hours; and (2) Within 5 minutes of completion of the weathering test required by paragraph...

  3. 46 CFR 160.060-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... closure for buoyant vests must— (1) Be tested for weathering. The Coast Guard will determine which one or...) for 24 hours; and (2) Within 5 minutes of completion of the weathering test required by paragraph...

  4. 46 CFR 160.060-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... closure for buoyant vests must— (1) Be tested for weathering. The Coast Guard will determine which one or...) for 24 hours; and (2) Within 5 minutes of completion of the weathering test required by paragraph...

  5. 46 CFR 160.060-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... closure for buoyant vests must— (1) Be tested for weathering. The Coast Guard will determine which one or...) for 24 hours; and (2) Within 5 minutes of completion of the weathering test required by paragraph...

  6. 46 CFR 160.060-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... closure for buoyant vests must— (1) Be tested for weathering. The Coast Guard will determine which one or...) for 24 hours; and (2) Within 5 minutes of completion of the weathering test required by paragraph...

  7. Northern Monterey Bay upwelling shadow front: Observations of a coastally and surface-trapped buoyant plume

    USGS Publications Warehouse

    Woodson, C.B.; Washburn, L.; Barth, J.A.; Hoover, D.J.; Kirincich, A.R.; McManus, M.A.; Ryan, J.P.; Tyburczy, J.

    2009-01-01

    During the upwelling season in central California, northwesterly winds along the coast produce a strong upwelling jet that originates at Point A??o Nuevo and flows southward across the mouth of Monterey Bay. A convergent front with a mean temperature change of 3.77 ?? 0.29??C develops between the warm interior waters and the cold offshore upwelling jet. To examine the forcing mechanisms driving the location and movement of the upwelling shadow front and its effects on biological communities in northern Monterey Bay, oceanographic conditions were monitored using cross-shelf mooring arrays, drifters, and hydrographic surveys along a 20 km stretch of coast extending northwestward from Santa Cruz, California, during the upwelling season of 2007 (May-September). The alongshore location of the upwelling shadow front at the northern edge of the bay was driven by: regional wind forcing, through an alongshore pressure gradient; buoyancy forces due to the temperature change across the front; and local wind forcing (the diurnal sea breeze). The upwelling shadow front behaved as a surface-trapped buoyant current, which is superimposed on a poleward barotropic current, moving up and down the coast up to several kilometers each day. We surmise that the front is advected poleward by a preexisting northward barotropic current of 0.10 m s-1 that arises due to an alongshore pressure gradient caused by focused upwelling at Point A??o Nuevo. The frontal circulation (onshore surface currents) breaks the typical two-dimensional wind-driven, cross-shelf circulation (offshore surface currents) and introduces another way for water, and the material it contains (e.g., pollutants, larvae), to go across the shelf toward shore.Copyright 2009 by the American Geophysical Union.

  8. Filament formation and evolution in buoyant coastal waters: Observation and modelling

    NASA Astrophysics Data System (ADS)

    Iermano, Ilaria; Liguori, Giovanni; Iudicone, Daniele; Buongiorno Nardelli, Bruno; Colella, Simone; Zingone, Adriana; Saggiomo, Vincenzo; Ribera d'Alcalà, Maurizio

    2012-11-01

    This paper presents a detailed analysis of the formation and subsequent evolution of filament-like structures observed in a relatively small area of the mid-Tyrrhenian Sea (Mediterranean Sea). The filament dynamics and potential impact on the cross-shelf exchange budget are investigated based on a combined use of remote sensing imagery, in situ data and numerical modelling. The complexity of these phenomena is shown by focusing on four distinct events that led to cross-shelf transport, each representative of a different dynamic process and a distinct expected impact on the coastal area. A systematic analysis of available observations for the years 1998-2006 underlines the role of the interplay of atmospheric freshwater fluxes, river loads and wind stress variations, which may create favourable conditions for the convergence of shelf waters (particularly at coastal capes) and the subsequent formation of short-lived filaments along the coast. The response of the buoyant coastal waters to periods of wind reversal and fluctuating freshwater discharge rates is examined through idealised Regional Ocean Modeling System (ROMS) simulations. The filaments observed in remote sensing imagery were well reproduced by the numerical exercise, where the filaments appear as organised submesoscale structures that possess high relative vorticity and develop at the river mouths or adjacent capes. In both scenarios, the filaments appear largely determined by (i) the presence of a buoyancy anomaly, (ii) the angle between the wind pulse direction and the coast and (iii) irregularities in the coastal profile. The ensemble of results suggests that the occurrence of such transient, intense structures may contribute considerably to the biological variability and cross-shelf exchange in coastal areas with similar traits.

  9. Observations and numerical modelling of a non-buoyant front in the Tay Estuary, Scotland

    NASA Astrophysics Data System (ADS)

    Neill, S. P.; Copeland, G. J. M.; Ferrier, G.; Folkard, A. M.

    2004-01-01

    Acoustic Doppler current profiler (ADCP) and density data have been collected for a section of front which consistently occurs on the flood tide along a break in bathymetry in the Tay Estuary. Lateral velocity shear in a vertical profile through the front was measured to be 0.52 s -1. An estuarine cross-sectional numerical model was developed with buoyancy-driven flow. Results from the numerical model showed that shears of such magnitude cannot be produced by buoyancy alone. Instead, a hypothesis was devised for the generation of the bathymetry-aligned front, and tested using the numerical model. The flooding current flows over sandbanks at the southern bank of the estuary and is then directed over (rather than along) the bathymetry break due to a sudden topographic restriction at the Tayport Narrows. Due to tidal phase effects, this overbank flow has a lower density than the ambient main channel water, hence behaving as a buoyant plume. The plume entrains higher density bottom water and a recirculation cell is set up in the lee of the bathymetry break. A surface convergent front occurs because a corresponding towards-bank flow (confirmed by field data) occurs in the centre of the channel. The numerical model was applied to this configuration using suitable initial and boundary conditions based on field observations. Lateral velocity profiles and the strength of shear show good agreement with the field data. It is suggested that the presence of a density gradient is required to generate the front but is not the main driving force.

  10. Toward the Understanding and Optimization of Chimneys for Buoyantly Driven Biomass Stoves

    NASA Astrophysics Data System (ADS)

    Prapas, Jason

    The vast majority of indoor combustion devices in the developed world make use of stacks (flues, vents, chimneys, smokestacks) to channel flue gases out of the operator space. In the developing world, where indoor air pollution kills several million people every year, the use of chimneys with biomass cooking and heating stoves has been met with limited success and a high level of controversy. Due to a lack of theoretical understanding, design criteria, poorly executed installation practices, and/or insufficient maintenance routines, many chimney stoves have exhibited inadequate indoor emissions reductions in addition to low thermal efficiencies. This work aims (a) shed light on the physical phenomenon of the "stack effect" as it pertains to dynamic, non-adiabatic, buoyancy-driven stoves (b) apply new understanding toward the optimization of two types of biomass chimney stoves: plancha or griddle type stoves popular in Central America and two-pot stoves common in South America. A numerical heat and fluid flow model was developed that takes into account the highly-coupled variables and dynamic nature of such systems. With a comprehensive physical model, parameter studies were conducted to determine how several field-relevant variables influence the performance of stack-outfitted systems. These parameters include, but are not limited to: power/wood consumption rate, chimney geometry, stove geometry, material properties, heat transfer, and ambient conditions. An instrumented experimental chimney was built to monitor relationships between air flow, differential pressure, gas temperatures, emissions, and thermal efficiency. The draft provided by chimneys was found to have a strong influence over the bulk air-to-fuel ratio of buoyantly-driven cookstoves, greatly affecting the stove's overall performance by affecting gas temperatures, emissions, and efficiency. Armed with new information from the modeling and experimental work, two new stoves were designed and optimized to

  11. Role of mixing in the structure and evolution of a buoyant discharge plume

    NASA Astrophysics Data System (ADS)

    Chen, Fei; MacDonald, Daniel G.

    2006-11-01

    A field study to examine the near-field structure of a buoyant discharge plume, and the turbulent mixing associated with its evolution, was conducted in Mount Hope Bay near Somerset, Massachusetts. The study focused on a 50 m3/s thermal discharge, approximately 5° C warmer than ambient waters, emanating from an electrical generating facility. The discharge enters the Bay through a 10 m wide surface canal creating a plume that has many attributes in common with larger scale river plumes. At a distance of 200 m, the plume was characterized by a core with high velocity and 2 ˜ 3°C higher temperature than ambient water. At this location the core of the plume was observed with a width of approximately 150 m during ebb tide, remaining bottom attached along the plume centerline. Analysis of the temperature budget with respect to specific isotherms yielded values of Reynolds temperature flux , on the order of 10-2°C m/s, suggesting buoyancy flux values (B = gα) of order 10-5 m2/s3. These values are consistent with the turbulent energy expected to enter the system as a result of bottom stress, implying that mixing across the first 200 m is driven by bottom friction and is most active along the edges of the plume where thermal gradients are strong. The industrial plume studied here is dynamically similar to larger geophysical plumes, such as river plumes. However, the aspect ratio is critical in determining whether mixing driven by bottom friction is important in the overall evolution of the plume.

  12. Trace Metal and Sulfur Dynamics in the First Meter of Buoyant Hydrothermal Vent Plumes

    NASA Astrophysics Data System (ADS)

    Findlay, A.; Gartman, A.; Shaw, T. J.; Luther, G. W., III

    2014-12-01

    The speciation and reactivity of metals and metal sulfides within the buoyant plume is critical to determining the ultimate fate of metals emitted from hydrothermal vents. The concentration, size fractionation, and partitioning of trace metals (Fe, Mn, Cu, Co, Zn, Cd, Pb) were determined within the first meter of the rising plume at three vent fields (TAG, Snakepit, and Rainbow) along the Mid-Atlantic Ridge. At Rainbow, total Fe concentrations exceed total sulfide concentrations by an order of magnitude, whereas at the other two sites, total Fe and total sulfide concentrations are nearly equal. At all three sites, Mn and Fe are primarily in the filtered (< 0.2 μm) fraction and Cu, Co, Zn, Cd, and Pb are mainly in the unfiltered fraction. At TAG and Snakepit, unfiltered copper is correlated with unfiltered cobalt, and unfiltered zinc is correlated with unfiltered cadmium and lead. At Rainbow, unfiltered zinc, cadmium and lead are correlated, but unfiltered copper and cobalt are not, indicating precipitation dynamics at Rainbow are different than those at TAG and Snakepit due to bulk geochemical differences, including a higher iron to sulfide ratio. A sequential HCl/HNO3 leaching method was used to distinguish metals present in pyrite and chalcopyrite in both unfiltered and filtered samples. Significant portions of unfiltered Cu and Co were extracted in HNO3, whereas unfiltered Zn, Cd, and Pb were extracted in HCl. Up to 95 % of filtered Cu, Co, and Zn, up to 80% Cd, and up to 60 % Pb are only extractable in HNO3, indicating that a significant portion of metals < 0.2 μm are incorporated into a recalcitrant fraction such as nanoparticulate pyrite or chalcopyrite.

  13. Extinction and Scattering Properties of Soot Emitted from Buoyant Turbulent Diffusion Flames. Appendix F

    NASA Technical Reports Server (NTRS)

    Krishnan, S. S.; Lin, K.-C.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Extinction and scattering properties at wavelengths of 250-5200 nm were studied for soot emitted from buoyant turbulent diffusion flames in the long residence time regime where soot properties are independent of position in the overfire region and characteristic flame residence times. Flames burning in still air and fueled with gas (acetylene, ethylene, propane, and propylene) and liquid (benzene, toluene, cyclohexane, and n-heptane) hydrocarbon fuels were considered. Measured scattering patterns and ratios of total scattering/absorption cross sections were in good agreement with predictions based on the Rayleigh-Debye-Gans (RDG) scattering approximation in the visible. Measured depolarization ratios were roughly correlated by primary particle size parameter, suggesting potential for completing RDG methodology needed to make soot scattering predictions as well as providing a nonintrusive way to measure primary soot particle diameters. Measurements of dimensionless extinction coefficients were in good agreement with earlier measurements for similar soot populations and were independent of fuel type and wavelength except for reduced values as the near ultraviolet was approached. The ratios of the scattering/absorption refractive index functions were independent of fuel type within experimental uncertainties and were in good agreement with earlier measurements. The refractive index junction for absorption was similarly independent of fuel type but was larger than earlier reflectometry measurements in the infrared. Ratios of total scattering/absorption cross sections were relatively large in the visible and near infrared, with maximum values as large as 0.9 and with values as large as 0.2 at 2000 nm, suggesting greater potential for scattering from soot particles to affect flame radiation properties than previously thought.

  14. Extinction and Scattering Properties of Soot Emitted from Buoyant Turbulent Diffusion Flames. Appendix D

    NASA Technical Reports Server (NTRS)

    Krishnan, S. S.; Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Extinction and scattering properties at wavelengths of 250-5200 nm were studied for soot emitted from buoyant turbulent diffusion flames in the long residence time regime where soot properties are independent of position in the overfire region and characteristic flame residence times. Flames burning in still air and fueled with gas (acetylene, ethylene, propane, and propylene) and liquid (benzene, toluene, cyclohexane, and n-heptane) hydrocarbon fuels were considered Measured scattering patterns and ratios of total scattering/absorption cross sections were in good agreement with predictions based on the Rayleigh-Debye-Gans (RDG) scattering approximation in the visible. Measured depolarization ratios were roughly correlated by primary particle size parameter, suggesting potential for completing RDG methodology needed to make soot scattering predictions as well as providing a nonintrusive way to measure primary soot particle diameters. Measurements of dimensionless extinction coefficients were in good agreement with earlier measurements for similar soot populations and were independent of fuel type and wavelength except for reduced values as the near ultraviolet was approached. The ratios of the scattering/absorption refractive index functions were independent of fuel type within experimental uncertainties and were in good agreement with earlier measurements. The refractive index function for absorption was similarly independent of fuel type but was larger than earlier reflectometry measurements in the infrared. Ratios of total scattering/absorption cross sections were relatively large in the visible and near infrared, with maximum values as large as 0.9 and with values as large as 0.2 at 2000 nm, suggesting greater potential for scattering from soot particles to affect flame radiation properties than previously thought.

  15. Coral calcification under environmental change: a direct comparison of the alkalinity anomaly and buoyant weight techniques

    NASA Astrophysics Data System (ADS)

    Schoepf, Verena; Hu, Xinping; Holcomb, Michael; Cai, Wei-Jun; Li, Qian; Wang, Yongchen; Xu, Hui; Warner, Mark E.; Melman, Todd F.; Hoadley, Kenneth D.; Pettay, D. Tye; Matsui, Yohei; Baumann, Justin H.; Grottoli, Andréa G.

    2017-03-01

    Two primary methods—the buoyant weight (BW) and alkalinity anomaly (AA) techniques—are currently used to quantify net calcification rates ( G) in scleractinian corals. However, it remains unclear whether they are directly comparable since the few method comparisons conducted to date have produced inconsistent results. Further, such a comparison has not been made for tropical corals. We directly compared G BW and G AA in four tropical and one temperate coral species cultured under various pCO2, temperature, and nutrient conditions. A range of protocols for conducting alkalinity depletion incubations was assessed. For the tropical corals, open-top incubations with manual stirring produced G AA that were highly correlated with and not significantly different from G BW. Similarly, G AA of the temperate coral was not significantly different from G BW when incubations provided water motion using a pump, but were significantly lower than G BW by 16% when water motion was primarily created by aeration. This shows that the two techniques can produce comparable calcification rates in corals but only when alkalinity depletion incubations are conducted under specific conditions. General recommendations for incubation protocols are made, especially regarding adequate water motion and incubation times. Further, the re-analysis of published data highlights the importance of using appropriate regression statistics when both variables are random and measured with error. Overall, we recommend the AA technique for investigations of community and short-term day versus night calcification, and the BW technique to measure organism calcification rates integrated over longer timescales due to practical limitations of both methods. Our findings will facilitate the direct comparison of studies measuring coral calcification using either method and thus have important implications for the fields of ocean acidification research and coral biology in general.

  16. Rossby adjustment of a finite-length buoyant patch along a vertical wall

    NASA Astrophysics Data System (ADS)

    Helfrich, Karl

    2004-11-01

    The release of a patch of buoyant fluid of initial uniform depth H and width L0 perpendicular to a wall in a rotating system is reconsidered for a patch with finite length along the wall. The lower layer is slightly denser and much deeper. The finite length results in distinct end effects. At the downstream end (in the Kelvin wave direction) a semigeostrophic theory shows that the fluid intrudes along the wall as rarefaction terminated at a nose of zero width and depth. The nose speed increases to c_nose = 3.80 (g^' H)^1/2 for L0 arrow ∞. In a real fluid the presence of the lower layer leads to a blunt gravity current head rather than the thinning nose. For that case the theory is amended by joining the rarefaction to a bore condition of the form cb = c_b(g^', h_0, f), where cb is the bore speed, h0 is the depth of the layer along the wall at the bore head and f is the Coriolis frequency. The bore is attached to the rarefaction by a gravity current with uniform wall depth and width. The analytical solutions are compared to numerical solutions of the reduced-gravity shallow water equations. The modeling reveals that immediately after the release a Kelvin wave propagates away from the upstream termination of the patch and alters the geostrophically adjusted flow to a new, unstable state. The flow rapidly evolves into an array of vortices that prematurely shuts off the flux into the gravity current.

  17. Buoyant Turbulent Kinetic Energy Production in Steep-Slope Katabatic Flow

    NASA Astrophysics Data System (ADS)

    Oldroyd, Holly J.; Pardyjak, Eric R.; Higgins, Chad W.; Parlange, Marc B.

    2016-12-01

    We develop several critical concepts that should be considered when interpreting, modelling and designing future experiments for flows over sloping terrain. Vertical buoyancy fluxes in katabatic flows can be positive and a source of turbulent kinetic energy (TKE) despite the statically stable, thermal stratification that drives these flows. This phenomenon occurs when the ratio of along-slope to slope-normal kinematic heat fluxes is greater than the cotangent of the slope angle, suggesting a critical value of slope-angle steepness found in earlier studies. We provide field-data-based evidence that the along-slope heat flux may dominate the variables in this inequality, and therefore in generating buoyant TKE production or suppression over a steep slope. These data show the along-slope heat flux can be more variable and significantly larger in magnitude than the slope-normal component. The gradient Richardson number does not include the effects of the along-slope buoyancy; furthermore, none of the canonical stability parameters can properly reflect the TKE redistribution from turbulent transport divergence and the sink of TKE in cases of counter-gradient momentum fluxes, which we frequently observe near the peak of the katabatic jet. In such cases, canonical stability parameters inadequately represent the physical mechanisms associated with stability. These results have broad implications related to accurately modelling turbulence and surface exchanges over sloping terrain and illustrate the need to more thoroughly investigate the along-slope heat flux and its drivers, the meaning and definitions of stability, and the effects of non-local turbulent transport.

  18. Experimental study of heat and mass transfer in a buoyant countercurrent exchange flow

    NASA Astrophysics Data System (ADS)

    Conover, Timothy Allan

    Buoyant Countercurrent Exchange Flow occurs in a vertical vent through which two miscible fluids communicate, the higher-density fluid, residing above the lower-density fluid, separated by the vented partition. The buoyancy- driven zero net volumetric flow through the vent transports any passive scalars, such as heat and toxic fumes, between the two compartments as the fluids seek thermodynamic and gravitational equilibrium. The plume rising from the vent into the top compartment resembles a pool fire plume. In some circumstances both countercurrent flows and pool fires can ``puff'' periodically, with distinct frequencies. One experimental test section containing fresh water in the top compartment and brine (NaCl solution) in the bottom compartment provided a convenient, idealized flow for study. This brine flow decayed in time as the concentrations approached equilibrium. A second test section contained fresh water that was cooled by heat exchangers above and heated by electrical elements below and operated steadily, allowing more time for data acquisition. Brine transport was reduced to a buoyancy- scaled flow coefficient, Q*, and heat transfer was reduced to an analogous coefficient, H*. Results for vent diameter D = 5.08 cm were consistent between test sections and with the literature. Some results for D = 2.54 cm were inconsistent, suggesting viscosity and/or molecular diffusion of heat become important at smaller scales. Laser Doppler Velocimetry was used to measure velocity fields in both test sections, and in thermal flow a small thermocouple measured temperature simultaneously with velocity. Measurement fields were restricted to the plume base region, above the vent proper. In baseline periodic flow, instantaneous velocity and temperature were ensemble averaged, producing a movie of the average variation of each measure during a puffing flow cycle. The temperature movie revealed the previously unknown cold core of the puff during its early development. The

  19. Vortex-induced vibrations of a neutrally buoyant circular cylinder near a plane wall

    NASA Astrophysics Data System (ADS)

    Wang, X. K.; Hao, Z.; Tan, S. K.

    2013-05-01

    This paper presents an experimental study of the motions, drag force and vortex shedding patterns of an elastically mounted circular cylinder, which is held at various heights above a plane wall and is subject to vortex-induced vibration (VIV) in the transverse direction. The cylinder is neutrally buoyant with a mass ratio m=1.0 and has a low damping ratio ζ=0.0173. Effects of the gap ratio (S/D) ranged from 0.05 to 2.5 and the free-stream velocity (U) ranged from 0.15 to 0.65m/s (corresponding to 3000≤Re≤13 000, and 1.53≤U≤6.62) are examined. The flow around the cylinder has been measured using particle image velocimetry (PIV), in conjunction with direct measurements of the dynamic drag force on the cylinder using a piezoelectric load cell. Results of the vibrating cylinder under unbounded (or free-standing) condition, as well as those of a near-wall stationary cylinder at the same gap ratios, are also provided. For the free-standing cylinder, the transition from the initial branch to the upper branch is characterized by a switch of vortex pattern from the classical 2S mode to the newly-discovered 2PO mode by Morse and Williamson (2009). The nearby wall not only affects the amplitude and frequency of vibration, but also leads to non-linearities in the cylinder response as evidenced by the presence of super-harmonics in the drag force spectrum. In contrast to the case of a stationary cylinder that vortex shedding is suppressed below a critical gap ratio (S/D≈0.3), the elastically mounted cylinder always vibrates even at the smallest gap ratio S/D=0.05. Due to the proximity of the plane wall, the vortices shed from the vibrating cylinder that would otherwise be in a double-sided vortex street pattern (either 2S or 2PO mode) under free-standing condition are arranged into a single-sided pattern.

  20. A simple device for measuring the minimum current velocity to maintain semi-buoyant fish eggs in suspension

    USGS Publications Warehouse

    Mueller, Julia S.; Cheek, Brandon D.; Chen, Qingman; Groeschel, Jillian R.; Brewer, Shannon K.; Grabowski, Timothy B.

    2013-01-01

    Pelagic broadcast spawning cyprinids are common to Great Plains rivers and streams. This reproductive guild produces non-adhesive semi-buoyant eggs that require sufficient current velocity to remain in suspension during development. Although studies have shown that there may be a minimum velocity needed to keep the eggs in suspension, this velocity has not been estimated directly nor has the influence of physicochemical factors on egg buoyancy been determined. We developed a simple, inexpensive flow chamber that allowed for evaluation of minimum current velocity needed to keep semi-buoyant eggs in suspension at any time frame during egg development. The device described here has the capability of testing the minimum current velocity needed to keep semi-buoyant eggs in suspension at a wide range of physicochemical conditions. We used gellan beads soaked in freshwater for 0, 24, and 48 hrs as egg surrogates and evaluated minimum current velocities necessary to keep them in suspension at different combinations of temperature (20.0 ± 1.0° C, 25.0 ± 1.0° C, and 28.0 ± 1.0° C) and total dissolved solids (TDS; 1,000 mg L-1, 3,000 mg L-1, and 6,000 mg L-1). We found that our methodology generated consistent, repeatable results within treatment groups. Current velocities ranging from 0.001–0.026 needed to keep the gellan beads in suspension were negatively correlated to soak times and TDS and positively correlated with temperature. The flow chamber is a viable approach for evaluating minimum current velocities needed to keep the eggs of pelagic broadcast spawning cyprinids in suspension during development.

  1. Vertical distribution of buoyant Microcystis blooms in a Lagrangian particle tracking model for short-term forecasts in Lake Erie

    NASA Astrophysics Data System (ADS)

    Rowe, M. D.; Anderson, E. J.; Wynne, T. T.; Stumpf, R. P.; Fanslow, D. L.; Kijanka, K.; Vanderploeg, H. A.; Strickler, J. R.; Davis, T. W.

    2016-07-01

    Cyanobacterial harmful algal blooms (CHABs) are a problem in western Lake Erie, and in eutrophic fresh waters worldwide. Western Lake Erie is a large (3000 km2), shallow (8 m mean depth), freshwater system. CHABs occur from July to October, when stratification is intermittent in response to wind and surface heating or cooling (polymictic). Existing forecast models give the present location and extent of CHABs from satellite imagery, then predict two-dimensional (surface) CHAB movement in response to meteorology. In this study, we simulated vertical distribution of buoyant Microcystis colonies, and 3-D advection, using a Lagrangian particle model forced by currents and turbulent diffusivity from the Finite Volume Community Ocean Model (FVCOM). We estimated the frequency distribution of Microcystis colony buoyant velocity from measured size distributions and buoyant velocities. We evaluated several random-walk numerical schemes to efficiently minimize particle accumulation artifacts. We selected the Milstein scheme, with linear interpolation of the diffusivity profile in place of cubic splines, and varied the time step at each particle and step based on the curvature of the local diffusivity profile to ensure that the Visser time step criterion was satisfied. Inclusion of vertical mixing with buoyancy significantly improved model skill statistics compared to an advection-only model, and showed greater skill than a persistence forecast through simulation day 6, in a series of 26 hindcast simulations from 2011. The simulations and in situ observations show the importance of subtle thermal structure, typical of a polymictic lake, along with buoyancy in determining vertical and horizontal distribution of Microcystis.

  2. Passive buoyant tracers in the ocean surface boundary layer: 1. Influence of equilibrium wind-waves on vertical distributions

    NASA Astrophysics Data System (ADS)

    Kukulka, T.; Brunner, K.

    2015-05-01

    This paper is the first of a two part series that investigates passive buoyant tracers in the ocean surface boundary layer. The first part examines the influence of equilibrium wind-waves on vertical tracer distributions, based on large eddy simulations (LES) of the wave-averaged Navier-Stokes equation. The second part applies the model to investigate observations of buoyant microplastic marine debris, which has emerged as a major ocean pollutant. The LES model captures both Langmuir turbulence (LT) and enhanced turbulent kinetic energy input due to breaking waves (BW) by imposing equilibrium wind-wave statistics for a range of wind and wave conditions. Concentration profiles of LES agree well with analytic solutions obtained for an eddy diffusivity profile that is constant near the surface and transitions into the K-Profile Parameterization (KPP) profile shape at greater depth. For a range of wind and wave conditions, the eddy diffusivity normalized by the product of water-side friction velocity and mixed layer depth, h, mainly depends on a single nondimensional parameter, the peak wavelength (which is related to Stokes drift decay depth) normalized by h. For smaller wave ages, BW critically enhances near-surface mixing, while LT effects are relatively small. For greater wave ages, both BW and LT contribute to elevated near-surface mixing, and LT significantly increases turbulent transport at greater depth. We identify a range of realistic wind and wave conditions for which only Langmuir (and not BW or shear driven) turbulence is capable of deeply submerging buoyant tracers.

  3. From free jets to clinging wall jets: The influence of a horizontal boundary on a horizontally forced buoyant jet

    NASA Astrophysics Data System (ADS)

    Burridge, H. C.; Hunt, G. R.

    2017-02-01

    We investigate the incompressible turbulent jet formed when buoyant fluid is steadily ejected horizontally from a circular source into an otherwise quiescent uniform environment. As our primary focus, we introduce a horizontal boundary beneath the source. For sufficiently small separations, the jet attaches and clings to the boundary, herein the "clinging jet," before, farther downstream, the jet is pulled away from the boundary by the buoyancy force. For larger source-boundary separations, the buoyant jet is free to rise under the action of the buoyancy force, herein the "free jet." Based on measurements of saline jets in freshwater surroundings we deduce the conditions required for a jet to cling. We present a data set that spans a broad range of source conditions for the variation in volume flux (indicative of entrainment), jet perimeter, and jet centerline for both "clinging" and "free" jets. For source Froude numbers Fr0≥12 the data collapse when scaled, displaying universal behaviors for both clinging and free jets. Our results for the variation in the volume flux across horizontal planes, π Qjet , show that within a few jet lengths of the source, π Qjet for the clinging jet exceeds that of a free jet with identical source conditions. However, when examined in a coordinate following the jet centerline π Qjet for free jets is greater. Finally, we propose a new parametrization for an existing integral model which agrees well with our experimental data as well as with data from other studies. Our findings offer the potential to tailor the dilution of horizontal buoyant jets by altering the distance at which they are released from a boundary.

  4. Localized Density Instabilities Driven By Interface Shear and Their Influence on Removal of Sediment from Buoyant Plumes

    NASA Astrophysics Data System (ADS)

    Rouhnia, M.; Strom, K.

    2015-12-01

    Sediment removal rates from buoyant river discharges are typically scaled with particle settling velocity. However, some field and laboratory data suggest that removal can take place at rates higher than those predicted by individual particle settling. It is possible that these enhanced removal rates could potentially be due, at least in part, to mass settling of fluid and sediment near the fresh and saltwater interface. Fluid shear at the interface can mix the freshwater and sediment with the underlying saltwater and lead to pockets or bands of saltwater and sediment that are more dense than the underlying clear saltwater; resulting in an unstable configuration that can lead to rapid vertical transport of sediment. In this study, we perform laboratory experiments to study the enhancement of sediment removal from buoyant plumes under the effect of shear-driven gravitational instabilities. To do this, we ran a 5 cm deep layer of freshwater with flocculated kaolinite over a 50 cm deep basin of clear saltwater in a 1 m long glass flume under a range of upper layer velocities, concentrations, and initial stratification ratios. A Vectrino profiler is placed such that it constantly records velocity profiles from 2 cm above to 2 cm below the original interface. The velocity of the buoyant layer is controlled using a vertical head pipe at the flume inlet, and the Richardson number is varied from 0.05 to 0.25. The interface is monitored with a digital camera and a laser sheet, and Rhodamine B is added to the buoyant layer for better visualization. Snapshots from the video are used to observe the overall dynamics and developments of instabilities at the interface. The sediment concentration of the inflow and outflow of the system are continuously measured with a pair of OBS sensors, and floc size is measured with a floc imaging system and converted to a floc settling velocity. The difference in sediment concentration between the two OBS sensors is used along with a mass

  5. A semi-empirical model to predict the probability of capture of buoyant particles by a cylindrical collector through capillarity

    NASA Astrophysics Data System (ADS)

    Peruzzo, Paolo; Pietro Viero, Daniele; Defina, Andrea

    2016-11-01

    The seeds of many aquatic plants, as well as many propagulae and larvae, are buoyant and transported at the water surface. These particles are therefore subject to surface tension, which may enhance their capture by emergent vegetation through capillary attraction. In this work, we develop a semi-empirical model that predicts the probability that a floating particle is retained by plant stems and branches piercing the water surface, due to capillarity, against the drag force exerted by the flowing water. Specific laboratory experiments are also performed to calibrate and validate the model.

  6. Detection of Mycobacterium avium subsp. paratuberculosis by buoyant density centrifugation, sequence capture PCR and dot blot hybridisation.

    PubMed

    Halldórsdóttir, Stefania; Englund, Stina; Nilsen, Sigrun Fredsvold; Olsaker, Ingrid

    2002-07-22

    Detection of Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) by polymerase chain reaction (PCR) is often hampered by the lack of efficient methods for sample treatment. We report a protocol for analysis of faecal samples based on buoyant density centrifugation in Percoll and IS900 sequence capture PCR combined with a dot blot assay for detection of low-grade infection of M. paratuberculosis. Serial dilutions of M. paratuberculosis genomic DNA and M. paratuberculosis bacteria were used to assess the sensitivity of the method. The final evaluation was performed with spiked faecal samples, which also were analysed by culture. The presence of PCR inhibitory substances in processed faecal samples was evaluated by including a PCR internal control. By using buoyant density centrifugation, sequence capture PCR, and dot blot hybridisation, we achieved a sensitivity of 10(3)CFU (colony forming units)/g of faeces. The detection limit by culture was assessed to 10(2)CFU/g of faeces. We conclude that the described protocol is a fast and sensitive alternative to bacterial culture of faecal samples.

  7. A hybrid approach for the simulation of a nearly neutrally buoyant nanoparticle thermal motion in an incompressible Newtonian fluid medium.

    PubMed

    Uma, B; Radhakrishnan, R; Eckmann, D M; Ayyaswamy, P S

    2013-01-01

    A hybrid scheme based on Markovian fluctuating hydrodynamics of the fluid and a non-Markovian Langevin dynamics with the Ornstein-Uhlenbeck noise perturbing the translational and rotational equations of motion of a nanoparticle is employed to study the thermal motion of a nearly neutrally buoyant nanoparticle in an incompressible Newtonian fluid medium. A direct numerical simulation adopting an arbitrary Lagrangian-Eulerian based finite element method is employed in simulating the thermal motion of the particle suspended in the fluid contained in a cylindrical vessel. The instantaneous flow around the particle and the particle motion are fully resolved. The numerical results show that (a) the calculated temperature of the nearly neutrally buoyant Brownian particle in a quiescent fluid satisfies the equipartition theorem; (b) the translational and rotational decay of the velocity autocorrelation functions result in algebraic tails, over long time; (c) the translational and rotational mean square displacements of the particle obeys Stokes-Einstein and Stokes-Einstein-Debye relations, respectively; and (d) the parallel and perpendicular diffusivities of the particle closer to the wall are consistent with the analytical results, where available. The study has important implications for designing nanocarriers for targeted drug delivery.

  8. Numerical study of a buoyant plume from a multi-flue stack into a variable temperature gradient atmosphere.

    PubMed

    Velamati, Ratna Kishore; Vivek, M; Goutham, K; Sreekanth, G R; Dharmarajan, Santosh; Goel, Mukesh

    2015-11-01

    Air pollution is one of the major global hazards and industries have been one of its major contributors. This paper primarily focuses on analyzing the dispersion characteristics of buoyant plumes of the pollutant released from a multi-flue vertical stack into a variable temperature gradient atmosphere (α) in a constant-velocity cross wind using two stack configurations-inline and parallel. The study is conducted for different Froude numbers, Fr = 12.64, 9.55, and 8.27. The atmospheric temperature gradients considered for the study are 0, +1, +1.5, and +2 K/100 m. The numerical study is done using the commercial computational fluid dynamics (CFD) code FLUENT. The effects of stack configuration, α, and Fr on the plume characteristics are presented. It is observed that the plume rises higher and disperses over a larger area with the inline configuration due to better mixing and shielding effect. With higher α, it is seen that the plume rises initially and then descends due to variation of the buoyant force. The plume rise initially is strongly influenced by the momentum of the jet, and as it moves downstream, it is influenced by the cooling rate of the plume. Furthermore, the plume rises higher and disperses over a larger area with a decrease in Fr.

  9. Synthesis of buoyant metal-coated fly ash cenosphere and its excellent catalytic performance in dye degradation.

    PubMed

    Wang, Wei; Zhai, Jianping; Li, Qin

    2015-04-15

    In this work, Ag(+) and Ag(0) were absorbed onto the surface of 3-mercaptopropyltriethoxysilane modified fly ash cenospheres (FACs) in two Ag activation processes. The activation methods, avoiding traditional surface sensitization by SnCl2, successfully initiated electroless copper particles deposition for the preparation of buoyant Cu-FAC and CuAg-FAC composites. The CuAg-FAC had a much more uniform morphology than the Cu-FAC. The catalytic performance of the Cu-FAC and CuAg-FAC was examined by the reduction of Orange IV azo dye with the presence of NaBH4. 98.4% of Orange IV was rapidly reduced within 25 min by the CuAg-FAC, whereas 76.4% of Orange IV was removed by the Cu-FAC. The results reveal that the degradation processes matched well with the pseudo-first-order kinetics model, and rate constants of 0.057 and 0.186 min(-1) were obtained for the Cu-FAC and CuAg-FAC, respectively. Moreover, two other dyes of Orange II and Reactive Black 5 were also efficiently reduced by the CuAg-FAC which could be easily recycled and stably reused at least four times. These buoyant metal-coated FAC composites would be very useful in various catalytic reductions.

  10. The influence of buoyant convection on the nucleation of n-propanol in thermal diffusion cloud chambers.

    PubMed

    Ferguson, Frank T; Heist, Richard H; Nuth, Joseph A

    2010-05-28

    A two-dimensional numerical model has been applied to three thermal diffusion cloud chamber (TDCC) investigations of n-propanol in helium taken by two different research groups to provide a quantitative example of how the results in these chambers can be affected by buoyant convection. In the first set of TDCC data, corrections for buoyancy resolve an apparent discontinuity in critical supersaturation data and also yield nucleation rate data that tend to agree better with higher rate, expansion-based studies at the same temperature. In the second TDCC study, the nucleation of propanol was studied over an extended pressure range. When the model was applied to these data, the possible variation in supersaturation values due to convection induced by conditions at the chamber sidewall was found to be comparable in magnitude to the experimentally observed range and may be responsible for some of this observed pressure dependence. In the third TDCC study, the combination of an error in a transport property and buoyant convection appear responsible for a perceived pressure effect in the experimental data. After correcting for this transport property and for buoyancy, the results at higher temperatures agree quite closely with the predictions of classical nucleation theory.

  11. Self Induced Buoyant Blow Off in Upward Flame Spread on Thin Solid Fuels

    NASA Technical Reports Server (NTRS)

    Johnston, Michael C.; T'ien, James S.; Muff, Derek E.; Olson, Sandra L.; Ferkul, Paul V.

    2013-01-01

    ) is as follows: The observed one-sided extinction is a blow- off induced by buoyant entrainment. It is known that the flammable diffusion flame regime is bounded by quenching and blow ]off limits when varying incoming air velocity. The narrowest samples tested (between 2 and 5 cm) begin within the flammable range, but as the flame grows, the buoyancy driven air velocity increases at the neighborhood of the flame base. The initially stable flame crosses the extinguishment boundary resulting in a flame blow-off. When one-side of the flame extinguishes, the remaining side shrinks due to the reduced heat transfer to the solid. This reduces the induced velocity and the flame becomes stable. It is proposed that this may have implications to upward flame growth beyond this experiment.

  12. The effect of shearing on the buoyant migration of melt in compacting-dissolution channels

    NASA Astrophysics Data System (ADS)

    Baltzell, C.; Parmentier, E.; Liang, Y.; Tirupathi, S.

    2013-12-01

    Melt migration in the mantle by porous flow through compacting, high porosity dissolution channels may occur in a variety of settings including both the upwelling mantle beneath spreading centers and the flowing mantle wedge at convergent plate boundaries. Such channels may form by a positive feedback between dissolution and melt percolation. Previous studies [1, 2] have considered the compacting-dissolution channels in the presence of a uniform upwelling mantle flow. In this study the analysis of mantle flow beneath the plate boundaries was extended by introducing a horizontal shearing component. A numerical experiment was formulated using the finite element software deal.II [3] applying a high order Discontinuous Galerkin (DG) method to examine melt flow in a deforming, porous matrix. The conditions are similar to those in [2] except the addition of a prescribed horizontal shear component in the solid matrix. Melt migration occurs within a rectangular domain subject to horizontal periodic boundary conditions. Initially a Gaussian perturbation in the porosity at the base extends vertically through the domain defining a melt channel. By varying the shear and upwelling rates, the porosity and matrix dissolution were examined to determine the behavior of the channel and melt flow. Models of buoyant melt transport through dissolution channels in upwelling mantle sheared on horizontal planes show that shearing deformation introduces several effects that could have important consequences for melt migration. Shearing tends to rotate dissolution channels away from the vertical thus reducing the component of buoyancy acting along the channels and decreasing the stability of the channel. The channels remain more vertical than would be expected if they followed the matrix flow, as determined by the dissolution. Channels thus migrate horizontally relative to the mantle matrix and melt flows horizontally through dissolution channels. Evolution of the channels depends on the

  13. Is the 'Fast Halo' around Hawaii as imaged in the PLUME experiment direct evidence for buoyant plume-fed asthenosphere?

    NASA Astrophysics Data System (ADS)

    Morgan, J. P.; Shi, C.; Hasenclever, J.

    2010-12-01

    An intriguing spatial pattern of variations in shear-wave arrival times has been mapped in the PLUME ocean bottom experiment (Wolfe et al., 2009) around Hawaii. The pattern consists of a halo of fast travel times surrounding a disk of slow arrivals from waves traveling up though the plume. We think it is directly sensing the pattern of dynamic uplift of the base of a buoyant asthenosphere - the buoyancy of the plume conduit lifting a 'rim' of the cooler, denser mantle that the plume rises through. The PLUME analysis inverted for lateral shear velocity variations beneath the lithosphere, after removing the assumed 1-D model velocity structure IASP91. They found that a slow plume-conduit extends to at least 1200 km below the Hawaiian hotspot. In this inversion the slow plume conduit is — quite surprisingly - surrounded by a fast wavespeed halo. A fast halo is impossible to explain as a thermal halo around the plume; this should lead to a slow wavespeed halo, not a fast one. Plume-related shearwave anisotropy also cannot simply explain this pattern — simple vertical strain around the plume conduit would result in an anisotropic slow shear-wavespeed halo, not a fast one. (Note the PLUME experiment’s uniform ‘fast-halo’ structure from 50-400km is likely to have strong vertical streaking in the seismic image; Pacific Plate-driven shear across a low-viscosity asthenosphere would be expected to disrupt and distort any cold sheet of vertical downwelling structure between 50-400km depths so that it would no longer be vertical as it is in the 2009 PLUME image with its extremely poor vertical depth control.) If the asthenosphere is plume-fed, hence more buoyant than underlying mantle, then there can be a simple explanation for this pattern. The anomaly would be due to faster traveltimes resulting from dynamic relief at the asthenosphere-mesosphere interface; uplift of the denser mesosphere by the buoyancy of the rising plume increases the distance a wave travels

  14. On the dynamics of volcanic columns: A comparison of field data with a new model of negatively buoyant jets

    NASA Astrophysics Data System (ADS)

    Carazzo, G.; Kaminski, E.; Tait, S.

    2008-11-01

    Explosive volcanic eruptions propel high-velocity turbulent jets into the atmosphere and are one of the most powerful and dangerous turbulent flows on Earth. Such eruptions are particularly difficult to predict due to their unusual dynamics that allow the jet to form a high buoyant Plinian plume or dense pyroclastic flows when the column collapses. A major goal of physical volcanology has been to predict quantitatively the limit between the flow regimes, as a function of exit conditions specified at the vent, which requires a physical model constrained by geologic field data. A first generation of quasi-analytic models, developed over 20-30 years although qualitatively successful, has failed to achieve this goal, because they overestimate by more than one order of magnitude the mass flux at the transition. There has been no consensus on whether this mostly reflects poor knowledge of geologic parameters or inadequacies in the physical description of the dynamics. Direct numerical simulations bring considerable advances in the study of unsteady phenomena that occur within the volcanic column, but their complexity makes the deciphering of the underlying dynamics challenging. Here, we present a basis for a new generation of 1D-models that includes a more sophisticated description of the rate of entrainment of air into the jet as a function of its buoyancy. In this framework, we demonstrate that the inconsistency between previous 1D models and field data is due to the omission of a key ingredient in the modeling of turbulence: reduction of entrainment due to the high density of the volcanic jet. We show that negative buoyancy near the base of the jet reduces the coefficient governing turbulent mixing to much less than the value commonly assumed based on experimental studies of neutrally buoyant jets and positively buoyant plumes. The results of our new model, allowing for variable entrainment as a function of local Richardson number, greatly improve the quantitative

  15. Mechanistic modeling of fingering, nonmonotonicity, fragmentation, and pulsation within gravity/buoyant destabilized two-phase/unsaturated flow

    NASA Astrophysics Data System (ADS)

    Glass, Robert J.; Yarrington, Lane

    2003-03-01

    Fingering, nonmonotonicity, fragmentation, and pulsation within gravity/buoyant destabilized two-phase/unsaturated flow systems has been widely observed with examples in homogeneous to heterogeneous porous media, in single fractures to fracture networks, and for both wetting and nonwetting invasion. To model this phenomena, we consider a mechanistic approach based on forms of modified invasion percolation (MIP) that include gravity, the influence of the local interfacial curvature along the phase-phase interface, and the simultaneous invasion and reinvasion of both wetting and nonwetting fluids. We present example simulations and compare them to experimental data for three very different situations: (1) downward gravity-driven fingering of water into a dry, homogeneous, water-wettable, porous medium; (2) upward buoyancy-driven migration of gas within a water saturated, heterogeneous, water-wettable, porous medium; and (3) downward gravity-driven fingering of water into a dry, water-wettable, rough-walled fracture.

  16. A Field Evaluation of an External and Neutrally Buoyant Acoustic Transmitter for Juvenile Salmon: Implications for Estimating Hydroturbine Passage Survival

    PubMed Central

    Brown, Richard S.; Deng, Z. Daniel; Cook, Katrina V.; Pflugrath, Brett D.; Li, Xinya; Fu, Tao; Martinez, Jayson J.; Li, Huidong; Trumbo, Bradly A.; Ahmann, Martin L.; Seaburg, Adam G.

    2013-01-01

    Turbine-passed fish are exposed to rapid decreases in pressure which can cause barotrauma. The presence of an implanted telemetry tag increases the likelihood of injury or death from exposure to pressure changes, thus potentially biasing studies evaluating survival of turbine-passed fish. Therefore, a neutrally buoyant externally attached tag was developed to eliminate this bias in turbine passage studies. This new tag was designed not to add excess mass in water or take up space in the coelom, having an effective tag burden of zero with the goal of reducing pressure related biases to turbine survival studies. To determine if this new tag affects fish performance or susceptibility to predation, it was evaluated in the field relative to internally implanted acoustic transmitters (JSATS; Juvenile Salmon Acoustic Telemetry System) used widely for survival studies of juvenile salmonids. Survival and travel time through the study reach was compared between fish with either tag type in an area of high predation in the Snake and Columbia rivers, Washington. An additional group of fish affixed with neutrally-buoyant dummy external tags were implanted with passive integrated transponder (PIT) tags and recovered further downstream to assess external tag retention and injury. There were no significant differences in survival to the first detection site, 12 river kilometers (rkm) downstream of release. Travel times were also similar between groups. Conversely, externally-tagged fish had reduced survival (or elevated tag loss) to the second detection site, 65 rkm downstream. In addition, the retention study revealed that tag loss was first observed in fish recaptured approximately 9 days after release. Results suggest that this new tag may be viable for short term (<8 days) single-dam turbine-passage studies and under these situations, may alleviate the turbine passage-related bias encountered when using internal tags, however further research is needed to confirm this. PMID

  17. The Buoyant Filter Bioreactor: a high-rate anaerobic reactor for complex wastewater--process dynamics with dairy effluent.

    PubMed

    Haridas, Ajit; Suresh, S; Chitra, K R; Manilal, V B

    2005-03-01

    A novel high-rate anaerobic reactor, called "Buoyant Filter Bioreactor" (BFBR), has been developed for treating lipid-rich complex wastewater. The BFBR is able to decouple the biomass and insoluble COD retention time from the hydraulic retention time by means of a granular filter bed made of buoyant polystyrene beads. Filter clogging is prevented by an automatic backwash driven by biogas release, which fluidizes the granular filter bed in a downward direction. During filter backwash, the solids captured in the filter are reintroduced into the reaction zone of the reactor. The reaction zone is provided with a mixing system, which is independent of the hydraulic retention time. The performance of a laboratory-scale BFBR was studied for the treatment of dairy effluent, chosen as a model complex wastewater. The dairy effluent was not pre-treated for fat removal. The BFBR was operated over 400 d and showed greater than 85% COD removal at 10 kg COD/(m3/d). The COD conversion to methane in the BFBR was essentially complete. The BFBR performance improved with age, and with feed containing 3200 mg COD/l, the treated effluent had 120 mg COD/l and no turbidity. The hold-up of degradable biosolids, including scum, inside the BFBR was estimated using starvation tests. When load is increased, scum accumulates inside the BFBR and then decays after undergoing change from hydrophobic to hydrophilic. This is explained as the accumulation of fat solids, its conversion to insoluble long chain fatty acids and its further solubilization and degradation.

  18. A field evaluation of an external and neutrally buoyant acoustic transmitter for juvenile salmon: implications for estimating hydroturbine passage survival.

    PubMed

    Brown, Richard S; Deng, Z Daniel; Cook, Katrina V; Pflugrath, Brett D; Li, Xinya; Fu, Tao; Martinez, Jayson J; Li, Huidong; Trumbo, Bradly A; Ahmann, Martin L; Seaburg, Adam G

    2013-01-01

    Turbine-passed fish are exposed to rapid decreases in pressure which can cause barotrauma. The presence of an implanted telemetry tag increases the likelihood of injury or death from exposure to pressure changes, thus potentially biasing studies evaluating survival of turbine-passed fish. Therefore, a neutrally buoyant externally attached tag was developed to eliminate this bias in turbine passage studies. This new tag was designed not to add excess mass in water or take up space in the coelom, having an effective tag burden of zero with the goal of reducing pressure related biases to turbine survival studies. To determine if this new tag affects fish performance or susceptibility to predation, it was evaluated in the field relative to internally implanted acoustic transmitters (JSATS; Juvenile Salmon Acoustic Telemetry System) used widely for survival studies of juvenile salmonids. Survival and travel time through the study reach was compared between fish with either tag type in an area of high predation in the Snake and Columbia rivers, Washington. An additional group of fish affixed with neutrally-buoyant dummy external tags were implanted with passive integrated transponder (PIT) tags and recovered further downstream to assess external tag retention and injury. There were no significant differences in survival to the first detection site, 12 river kilometers (rkm) downstream of release. Travel times were also similar between groups. Conversely, externally-tagged fish had reduced survival (or elevated tag loss) to the second detection site, 65 rkm downstream. In addition, the retention study revealed that tag loss was first observed in fish recaptured approximately 9 days after release. Results suggest that this new tag may be viable for short term (<8 days) single-dam turbine-passage studies and under these situations, may alleviate the turbine passage-related bias encountered when using internal tags, however further research is needed to confirm this.

  19. Physiological considerations in applying laboratory-determined buoyant densities to predictions of bacterial and protozoan transport in groundwater: Results of in-situ and laboratory tests

    USGS Publications Warehouse

    Harvey, R.W.; Metge, D.W.; Kinner, N.; Mayberry, N.

    1997-01-01

    Buoyant densities were determined for groundwater bacteria and microflagellates (protozoa) from a sandy aquifer (Cape Cod, MA) using two methods: (1) density-gradient centrifugation (DGC) and (2) Stoke's law approximations using sedimentation rates observed during natural-gradient injection and recovery tests. The dwarf (average cell size, 0.3 ??m), unattached bacteria inhabiting a pristine zone just beneath the water table and a majority (~80%) of the morphologically diverse community of free- living bacteria inhabiting a 5-km-long plume of organically-contaminated groundwater had DGC-determined buoyant densities <1.019 g/cm3 before culturing. In the aquifer, sinking rates for the uncultured 2-??m size class of contaminant plume bacteria were comparable to that of the bromide tracer (1.9 x 10-3 M), also suggesting a low buoyant density. Culturing groundwater bacteria resulted in larger (0.8-1.3 ??m), less neutrally- buoyant (1.043-1.081 g/cm3) cells with potential sedimentation rates up to 64-fold higher than those predicted for the uncultured populations. Although sedimentation generally could be neglected in predicting subsurface transport for the community of free-living groundwater bacteria, it appeared to be important for the cultured isolates, at least until they readapt to aquifer conditions. Culturing-induced alterations in size of the contaminant-plume microflagellates (2-3 ??m) were ameliorated by using a lower nutrient, acidic (pH 5) porous growth medium. Buoyant densities of the cultured microflagellates were low, i.e., 1.024-1.034 g/cm3 (using the DGC assay) and 1.017-1.039 g/cm3 (estimated from in-situ sedimentation rates), suggesting good potential for subsurface transport under favorable conditions.

  20. A novel technique to neutralize the Yawing moment due to asymmetric thrust in a hybrid buoyant aircraft

    NASA Astrophysics Data System (ADS)

    Haque, Anwar U.; Asrar, Waqar; Omar, Ashraf A.; Sulaeman, Erwin; J. S Ali, Mohamed

    2016-03-01

    Dorsal fin is used in swimming animals like shark for the generation of thrust as well as to meet the requirement of the lateral stability. In the case of aircraft, rudders are normally used for the said requirement. In the present work, this nature inspired idea is explored for its application to neutralize the unavoidable asymmetric thrust produced by the twin engines of a hybrid buoyant aircraft. First, the estimation of asymmetric thrust is obtained with the help of analytical techniques for maximum thrust condition at 4 degree angle of attack. The moment generated by it is utilized for the sizing of a dorsal fin which looks similar to a tapered wing and is placed aft of the center of gravity. Wind tunnel testing at subsonic speed is carried out to explore the design features of this rotatable dorsal fin. It is found that a small rotation of 5 degree can generate the required moment. However, such rotation requires a complete pneumatic/electro-mechanical system and an alternative of it is to use a cambered airfoil for the dorsal fin installed at fixed location. Such a flow controlling device can also be used as an antenna mast, which is commonly installed out the fuselage of the aircraft for communication purposes. Moreover, by incorporating this technique, a pilot doesn't have to put an extra effort to make the aircraft stable in the presence of side wind.

  1. Linear stability of buoyant convective flow in a vertical channel with internal heat sources and a transverse magnetic field

    NASA Astrophysics Data System (ADS)

    Hudoba, A.; Molokov, S.

    2016-11-01

    Linear stability of buoyant convective flow of an electrically conducting fluid in a vertical channel owing to internal heat sources has been studied. The flow takes place in a transverse, horizontal magnetic field. The results show that up to four different local minima may be present in the neural stability curve. Up to two of these modes may be the most unstable depending, critically, on the value of the Hartmann number. Over a wide range of moderate to high Hartmann numbers, thermal waves dominate the instability. As the Hartmann number increases, however, this mode is strongly damped. Then the so-called Hartmann mode takes over, which involves the characteristic Hartmann layers at the walls appearing due to modification of the basic velocity profile by the magnetic field. Overall, for liquid metals at high magnetic fields, the basic flow is very stable. Variation of the Prandtl number in a wide range has also been performed as, depending on the type of an electrically conducting fluid (liquid metal or various kinds of electrolytes), the Prandtl number varies over several orders of magnitude. As may be expected, the increase of the Prandtl number lowers the instability threshold for the thermal waves.

  2. Axial allometry in a neutrally buoyant environment: effects of the terrestrial-aquatic transition on vertebral scaling.

    PubMed

    Jones, K E; Pierce, S E

    2016-03-01

    Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi-aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc-shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool-shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa.

  3. MULTI-PARAMETRIC STUDY OF RISING 3D BUOYANT FLUX TUBES IN AN ADIABATIC STRATIFICATION USING AMR

    SciTech Connect

    Martínez-Sykora, Juan; Cheung, Mark C. M.; Moreno-Insertis, Fernando

    2015-11-20

    We study the buoyant rise of magnetic flux tubes embedded in an adiabatic stratification using two-and three-dimensional, magnetohydrodynamic simulations. We analyze the dependence of the tube evolution on the field line twist and on the curvature of the tube axis in different diffusion regimes. To be able to achieve a comparatively high spatial resolution we use the FLASH code, which has a built-in Adaptive Mesh Refinement (AMR) capability. Our 3D experiments reach Reynolds numbers that permit a reasonable comparison of the results with those of previous 2D simulations. When the experiments are run without AMR, hence with a comparatively large diffusivity, the amount of longitudinal magnetic flux retained inside the tube increases with the curvature of the tube axis. However, when a low-diffusion regime is reached by using the AMR algorithms, the magnetic twist is able to prevent the splitting of the magnetic loop into vortex tubes and the loop curvature does not play any significant role. We detect the generation of vorticity in the main body of the tube of opposite sign on the opposite sides of the apex. This is a consequence of the inhomogeneity of the azimuthal component of the field on the flux surfaces. The lift force associated with this global vorticity makes the flanks of the tube move away from their initial vertical plane in an antisymmetric fashion. The trajectories have an oscillatory motion superimposed, due to the shedding of vortex rolls to the wake, which creates a Von Karman street.

  4. Numerical analysis of the angular motion of a neutrally buoyant spheroid in shear flow at small Reynolds numbers.

    PubMed

    Rosén, T; Einarsson, J; Nordmark, A; Aidun, C K; Lundell, F; Mehlig, B

    2015-12-01

    We numerically analyze the rotation of a neutrally buoyant spheroid in a shear flow at small shear Reynolds number. Using direct numerical stability analysis of the coupled nonlinear particle-flow problem, we compute the linear stability of the log-rolling orbit at small shear Reynolds number Re(a). As Re(a)→0 and as the box size of the system tends to infinity, we find good agreement between the numerical results and earlier analytical predictions valid to linear order in Re(a) for the case of an unbounded shear. The numerical stability analysis indicates that there are substantial finite-size corrections to the analytical results obtained for the unbounded system. We also compare the analytical results to results of lattice Boltzmann simulations to analyze the stability of the tumbling orbit at shear Reynolds numbers of order unity. Theory for an unbounded system at infinitesimal shear Reynolds number predicts a bifurcation of the tumbling orbit at aspect ratio λ(c)≈0.137 below which tumbling is stable (as well as log rolling). The simulation results show a bifurcation line in the λ-Re(a) plane that reaches λ≈0.1275 at the smallest shear Reynolds number (Re(a)=1) at which we could simulate with the lattice Boltzmann code, in qualitative agreement with the analytical results.

  5. In-situ optical and acoustical measurements of the buoyant cyanobacterium p. Rubescens: spatial and temporal distribution patterns.

    PubMed

    Hofmann, Hilmar; Peeters, Frank

    2013-01-01

    Optical (fluorescence) and acoustic in-situ techniques were tested in their ability to measure the spatial and temporal distribution of plankton in freshwater ecosystems with special emphasis on the harmful and buoyant cyanobacterium P. rubescens. Fluorescence was measured with the multi-spectral FluoroProbe (Moldaenke FluoroProbe, MFP) and a Seapoint Chlorophyll Fluorometer (SCF). In-situ measurements of the acoustic backscatter strength (ABS) were conducted with three different acoustic devices covering multiple acoustic frequencies (614 kHz ADCP, 2 MHz ADP, and 6 MHz ADV). The MFP provides a fast and reliable technique to measure fluorescence at different wavelengths in situ, which allows discriminating between P. rubescens and other phytoplankton species. All three acoustic devices are sensitive to P. rubescens even if other scatterers, e.g., zooplankton or suspended sediment, are present in the water column, because P. rubescens containing gas vesicles has a strong density difference and hence acoustic contrast to the ambient water and other scatterers. After calibration, the combination of optical and acoustical measurements not only allows qualitative and quantitative observation of P. rubescens, but also distinction between P. rubescens, other phytoplankton, and zooplankton. As the measuring devices can sample in situ at high rates they enable assessment of plankton distributions at high temporal (minutes) and spatial (decimeters) resolution or covering large temporal (seasonal) and spatial (basin scale) scales.

  6. Reactive multiphase flow at the pore-scale: the melting of a crystalline framework during the injection of buoyant hot volatiles

    NASA Astrophysics Data System (ADS)

    Andrea, P.; Huber, C.; Bachmann, O.; Chopard, B.

    2010-12-01

    Multiphase reactive flows occur naturally in various environments in the shallow subsurface, e.g. CO2 injections in saturated reservoirs, exsolved methane flux in shallow sediments and H20-CO2 volatiles in magmatic systems. Because of their multiphase nature together with the nonlinear feedbacks between reactions (dissolution/melting or precipitation) and the flow field at the pore-scale, the study of these dynamical processes remains a great challenge. In this study we focus on the injection of buoyant hot volatiles exsolved from a magmatic intrusion underplating a crystal-rich magma (porous medium). We use some simple theoretical models and a pore-scale multiphase reactive lattice Boltzmann model to investigate how the heat carried by the volatile phase affects the evolution of the porous medium spatially and temporally. We find that when the reaction rate is relatively slow and when the injection rate of volatiles is large (high injection Capillary number), the dissolution of the porous medium can be described by a local Peclet number (ratio of advective to diffusive flux of heat/reactant in the main gas channel). When the injection rate of volatile is reduced, or when the reaction rate is large, the dynamics transition to more complex regimes, where subvertical gas channels are no longer stable and can break into disconnected gas slugs. For the case of the injection of hot volatiles in crystal-rich magmatic systems, we find that the excess enthalpy advected by buoyant volatiles penetrates the porous medium over distances ~r Pe, where r is the average radius of the volatile channel (~pore size). The transport of heat by buoyant gases through a crystal mush is therefore in most cases limited to distances < meters. Our results also suggest that buoyant volatiles can carry chemical species (Li,F, Cl) far into a mush as their corresponding local Peclet number is several orders of magnitude greater than that for heat, owing to their low diffusion coefficients.

  7. Time resolved measurements of vortex-induced vibrations of a positively buoyant tethered sphere in uniform water flow

    NASA Astrophysics Data System (ADS)

    Eshbal, L.; Krakovich, A.; van Hout, R.

    2012-11-01

    Vortex-induced vibrations (VIV) of a positively buoyant (light) tethered sphere in uniform flow as well as its wake characteristics were measured in a closed loop water channel. Experiments were performed at free stream velocities ranging between 0.048 and 0.22 m/s, corresponding to sphere Reynolds numbers ranging from ReD=430 to 1925. The measurements were done using high-speed sphere tracking as well as time resolved particle image velocimetry in a horizontal plane located at the sphere's center. Until the Hopf bifurcation, the sphere remained stationary and the wake was characterized by a train of hairpin vortices exhibiting near-symmetry in the vertical plane similar to stationary sphere visualization results. For our limited parameter range, the amplitude response of two different data sets (same sphere and free stream velocity but different water viscosity) collapsed better when plotted versus ReD than when plotted versus the reduced velocity, U*. The amplitude response beyond the first bifurcation displayed continuously increasing rms amplitudes in agreement with the sphere's small mass parameter (

  8. Hazardous or not - Are adult and juvenile individuals of Potamopyrgus antipodarum affected by non-buoyant microplastic particles?

    PubMed

    Imhof, Hannes K; Laforsch, Christian

    2016-11-01

    Microplastic has been ubiquitously detected in freshwater ecosystems. A variety of freshwater organisms were shown to ingest microplastic particles, while a high potential for adverse effects are expected. However, studies addressing the effect of microplastic in freshwater species are still scarce compared to studies on marine organisms. In order to gain further insights into possible adverse effects of microplastic particles on freshwater invertebrates and to set the base for further experiments we exposed the mud snail (Potampoyrgus antipodarum) to a large range of common and environmentally relevant non-buoyant polymers (polyamide, polyethylene terephthalate, polycarbonate, polystyrene, polyvinylchloride). The impact of these polymers was tested by performing two exposure experiments with irregular shaped microplastic particles with a broad size distribution in a low (30%) and a high microplastic dose (70%) in the food. First, possible effects on adult P. antipodarum were assessed by morphological and life-history parameters. Second, the effect of the same mixture on the development of juvenile P. antipodarum until maturity was analyzed. Adult P. antipodarum showed no morphological changes after the exposure to the microplastic particles, even if supplied in a high dose. Moreover, although P. antipodarum is an established model organism and reacts especially sensitive to endocrine active substances no effects on embryogenesis were detected. Similarly, the juvenile development until maturity was not affected. Considering, that most studies showing effects on marine and freshwater invertebrates mostly exposed their experimental organisms to very small (≤20 μm) polystyrene microbeads, we anticipate that these effects may be highly dependent on the chemical composition of the polymer itself and the size and shape of the particles. Therefore, more studies are necessary to enable the identification of harmful synthetic polymers as some of them may be

  9. Buoyant plumes and wakes.

    NASA Technical Reports Server (NTRS)

    Fay, J. A.

    1973-01-01

    The problem of mixing of pollutants induced by vehicular motions is considered as an example of dispersion that is initially unaffected by atmospheric turbulence. Some models are discussed that have proven helpful in understanding certain aspects of the problem of dispersion of air pollutants in the atmosphere. However, the considerable variability of atmospheric flow, as compared with a laboratory flow, makes the application of these models, both experimental and theoretical, of limited scientific usefulness to the prediction of ambient air-pollutant levels.

  10. Buoyant Cable Antenna System

    DTIC Science & Technology

    2008-07-02

    instance, Nitinol is comprised of nickel and titanium. When cool, one or more strands of such material may be bent and deployed as desired from the...considerable and may be in the range of about 35,000 to 70,000 psi. The electrical resistance of Nitinol is rather high and may be in the range of

  11. Buoyant despite Downturn

    ERIC Educational Resources Information Center

    Berry, John N., III; Fialkoff, Francine; Fox, Bette-Lee; Hadro, Josh; Horrocks, Norman; Kuzyk, Raya; Oder, Norman

    2009-01-01

    Even as libraries face the economic downturn, a record-setting number of people attended the American Library Association (ALA) annual conference in Chicago, July 9-15. The tough economy, however, was felt in the number of exhibitors, which declined from the previous record set in 2007 in Washington, DC, and in anecdotal evidence that suggested…

  12. JBFA - buoyant flight

    NASA Technical Reports Server (NTRS)

    Ohari, T.

    1982-01-01

    A method was developed whereby a balloon was used to carry lumber out of a forest in order to continue lumber production without destroying the natural environment and view of the forest. Emphasis was on the best shape for a logging balloon, development of a balloon logging system suitable for cutting lumber and safety plans, tests on balloon construction and development of netting, and weather of mountainous areas, especially solutions to problems caused by winds.

  13. Turbulent dispersion of slightly buoyant oil droplets and turbulent breakup of crude oil droplets mixed with dispersants

    NASA Astrophysics Data System (ADS)

    Gopalan, Balaji

    In part I, high speed in-line digital holographic cinematography is used for studying turbulent diffusion of slightly buoyant 0.5-1.2 mm diameter diesel droplets (specific gravity of 0.85) and 50 mum diameter neutral density particles. Experiments are performed in a 50x50x70 mm3 sample volume in a controlled, nearly isotropic turbulence facility, which is characterized by 2-D PIV. An automated tracking program has been used for measuring velocity time history of more than 17000 droplets and 15000 particles. The PDF's of droplet velocity fluctuations are close to Gaussian for all turbulent intensities ( u'i ). The mean rise velocity of droplets is enhanced or suppressed, compared to quiescent rise velocity (Uq), depending on Stokes number at lower turbulence levels, but becomes unconditionally enhanced at higher turbulence levels. The horizontal droplet velocity rms exceeds the fluid velocity rms for most of the data, while the vertical ones are higher than the fluid only at the highest turbulence level. The scaled droplet horizontal diffusion coefficient is higher than the vertical one, for 1 < u'i /Uq < 5, consistent with trends of the droplet velocity fluctuations. Conversely, the scaled droplet horizontal diffusion timescale is smaller than the vertical one due to crossing trajectories effect. The droplet diffusion coefficients scaled by the product of turbulence intensity and an integral length scale is a monotonically increasing function of u'i /Uq. Part II of this work explains the formation of micron sized droplets in turbulent flows from crude oil droplets pre-mixed with dispersants. Experimental visualization shows that this breakup starts with the formation of very long and quite stable, single or multiple micro threads that trail behind millimeter sized droplets. These threads form in regions with localized increase in concentration of surfactant, which in turn depends on the flow around the droplet. The resulting reduction of local surface tension

  14. Some factors affecting the use of lighter than air systems. [economic and performance estimates for dirigibles and semi-buoyant hybrid vehicles

    NASA Technical Reports Server (NTRS)

    Havill, C. D.

    1974-01-01

    The uses of lighter-than-air vehicles are examined in the present day transportation environment. Conventional dirigibles were found to indicate an undesirable economic risk due to their low speeds and to uncertainties concerning their operational use. Semi-buoyant hybrid vehicles are suggested as an alternative which does not have many of the inferior characteristics of conventional dirigibles. Economic and performance estimates for hybrid vehicles indicate that they are competitive with other transportation systems in many applications, and unique in their ability to perform some highly desirable emergency missions.

  15. 1/12-Scale mixing interface visualization and buoyant particle release tests in support of Tank 241-SY-101 hydrogen mitigation

    SciTech Connect

    Eschbach, E.J.; Enderlin, C.W.

    1993-10-01

    In support of tank waste safety programs, visualization tests were performed in the 1/12-scale tank facility, using a low-viscosity simulant. The primary objective of the tests was to obtain video records of the transient jet-sludge interaction. The intent is that these videos will provide useful qualitative data for comparison with model predictions. Two tests were initially planned: mixing interface visualization (MIV) and buoyant particle release (BPR). Completion of the buoyant particle release test was set aside in order to complete additional MIV tests. Rheological measurements were made on simulant samples before testing, and the simulant was found to exhibit thixotropic behavior. Shear vane measurements were also made on an in-situ analog of the 1/12-scale tank simulant. Simulant shear strength has been observed to be time dependent. The primary objective of obtaining video records of jet-sludge interaction was satisfied, and the records yielded jet location information which may be of use in completing model comparisons. The modeling effort is not part of this task, but this report also discusses test specific instrumentation, visualization techniques, and shear vane instrumentation which would enable improved characterization of jet-sludge interaction and simulant characteristics.

  16. HGSYSTEM/UF{sub 6} model enhancements for plume rise and dispersion around buildings, lift-off of buoyant plumes, and robustness of numerical solver

    SciTech Connect

    Hanna, S.R.; Chang, J.C.

    1997-01-01

    The HGSYSTEM/UF{sub 6} model was developed for use in preparing Safety Analysis Reports (SARs) by estimating the consequences of possible accidental releases of UF{sub 6} to the atmosphere at the gaseous diffusion plants (GDPs) located in Portsmouth, Ohio, and Paducah, Kentucky. Although the latter report carries a 1996 date, the work that is described was completed in late 1994. When that report was written, the primary release scenarios of interest were thought to be gas pipeline and liquid tank ruptures over open terrain away from the influence of buildings. However, upon further analysis of possible release scenarios, the developers of the SARs decided it was necessary to also consider accidental releases within buildings. Consequently, during the fall and winter of 1995-96, modules were added to HGSYSTEM/UF{sub 6} to account for flow and dispersion around buildings. The original HGSYSTEM/UF{sub 6} model also contained a preliminary method for accounting for the possible lift-off of ground-based buoyant plumes. An improved model and a new set of wind tunnel data for buoyant plumes trapped in building recirculation cavities have become available that appear to be useful for revising the lift-off algorithm and modifying it for use in recirculation cavities. This improved lift-off model has been incorporated in the updated modules for dispersion around buildings.

  17. Simulation of plume rise: Study the effect of stably stratified turbulence layer on the rise of a buoyant plume from a continuous source by observing the plume centroid

    NASA Astrophysics Data System (ADS)

    Bhimireddy, Sudheer Reddy; Bhaganagar, Kiran

    2016-11-01

    Buoyant plumes are common in atmosphere when there exists a difference in temperature or density between the source and its ambience. In a stratified environment, plume rise happens until the buoyancy variation exists between the plume and ambience. In a calm no wind ambience, this plume rise is purely vertical and the entrainment happens because of the relative motion of the plume with ambience and also ambient turbulence. In this study, a plume centroid is defined as the plume mass center and is calculated from the kinematic equation which relates the rate of change of centroids position to the plume rise velocity. Parameters needed to describe the plume are considered as the plume radius, plumes vertical velocity and local buoyancy of the plume. The plume rise velocity is calculated by the mass, momentum and heat conservation equations in their differential form. Our study focuses on the entrainment velocity, as it depicts the extent of plume growth. This entrainment velocity is made up as sum of fractions of plume's relative velocity and ambient turbulence. From the results, we studied the effect of turbulence on the plume growth by observing the variation in the plume radius at different heights and the centroid height reached before loosing its buoyancy.

  18. Horizontal evolution of tidally modulated buoyant plumes and the subsequent genesis of non linear internal waves as observed with an AUV based microstructure profiler.

    NASA Astrophysics Data System (ADS)

    toberman, matthew; Inall, Mark; Boyd, Tim

    2013-04-01

    The tidally modulated outflow of brackish water from a sea loch forms a thin stable surface layer that propagates into the coastal ocean as a buoyant gravity current, transporting nutrients and sediments, as well as fresh water, heat and momentum. The fresh intrusion propagates as an undular bore, and the introduced stratification supports trains of non-linear internal waves (NLIWs). In February 2011 an Autonomous Underwater Vehicle (AUV) was used on repeated reciprocal transects to make simultaneous CTD, ADCP and shear microstructure measurements of the evolution of these phenomena in conjunction with conventional mooring measurements. AUV-based temperature and salinity signals of NLIWs of depression were observed together with increased turbulent kinetic energy dissipation rates of over two orders of magnitude within and in the wake of the NLIWs. Repeated measurements over several tidal cycles allow a unique opportunity to investigate the horizontal structure of these phenomena, the interaction of each tidally driven pulse with ambient stratification and the remnants of previous plumes, as well as the genesis of and subsequent mixing induced by the NLIWs.

  19. Numerical studies of the effects of neutrally buoyant large particles on turbulent channel flow at the friction Reynolds number up to 395

    NASA Astrophysics Data System (ADS)

    Yu, Zhaosheng; Wang, Yu; Shao, Xueming

    2012-11-01

    A direct-forcing fictitious domain method was employed to perform fully-resolved numerical simulations of turbulent channel flow laden with large neutrally buoyant particles at constant pressure gradients. The effects of the particles on the turbulence (including the fluid-phase average velocity, the root-mean-square (rms) of the velocity fluctuation, the probability density function of the velocity and the vortex structures) at the friction Reynolds number of 180 and 395 were investigated. The results show that the drag-reduction effect caused by the spherical particle at low particle volumes is very small. The presence of particles decreases the maximum rms of streamwise velocity fluctuation near wall via weakening the large-scale streamwise vortices, and on the other hand increases the rms of transverse and spanwise fluctuating velocities in vicinity of the wall via inducing smaller-scale vortices. The effects of the particles on the fluid velocity PDF (probability density function) normalized with the rms velocity are small, irrespective of the particle size, particle volume fraction and Reynolds number. The work was supported by the National Natural Science Foundation of China (Nos. 11072217 and 11132008), the Fundamental Research Funds for the Central Universities, and the Program for New Century Excellent Talents in University.

  20. Observations of persistent Leonid meteor trails: 4. Buoyant rise/vortex formation as mechanism for creation of parallel meteor train pairs

    NASA Astrophysics Data System (ADS)

    Zinn, John; Drummond, Jack

    2005-04-01

    In this paper we present numerical computations designed to demonstrate effects associated with the buoyant rise of persistent trails produced by large Leonid meteors in cases where the meteor velocity vector has a large horizontal component. We model the meteor trail as a hot cylindrical volume in an equilibrium atmosphere. The computed results show the hot cylinder first expanding radially and then rising because of buoyancy, while evolving into a pair of counterrotating linear vortices. These line vortex phenomena are offered as an explanation for the otherwise mysterious parallel pairs of trails that are often observed. We also show some high-resolution images of double meteor trails observed during the high Leonid meteor activity of 1998-2002. For the case of the Diamond Ring event we compare computed and measured luminosity profiles for the sodium 589 nm emission and for the red-near IR O2 atmospheric band (O2(b1Σg+) - O2(X3Σg-)) emission.

  1. Infectious hepatitis A virus particles produced in cell culture consist of three distinct types with different buoyant densities in CsCl.

    PubMed Central

    Lemon, S M; Jansen, R W; Newbold, J E

    1985-01-01

    Although hepatitis A virus (HAV) released by infected BS-C-1 cells banded predominantly at 1.325 g/cm3 (major component) in CsCl, smaller proportions of infectious virions banded at 1.42 g/cm3 (dense HAV particles) and at 1.27 g/cm3 (previously unrecognized light HAV particles). cDNA-RNA hybridization confirmed the banding of viral RNA at each density, and immune electron microscopy demonstrated apparently complete viral particles in each peak fraction. The ratio of the infectivity (radioimmunofocus assay) titer to the antigen (radioimmunoassay) titer of the major component was approximately 15-fold greater than that of dense HAV particles and 4-fold that of light HAV particles. After extraction with chloroform, the buoyant density of light and major component HAV particles remained unchanged, indicating that the lower density of the light particles was not due to association with lipids. Light particles also banded at a lower density (1.21 g/cm3) in metrizamide than did the major component (1.31 g/cm3). Dense HAV particles, detected by subsequent centrifugation in CsCl, were indistinguishable from the major component when first banded in metrizamide (1.31 g/cm3). However, dense HAV particles recovered from CsCl subsequently banded at 1.37 g/cm3 in metrizamide. Electrophoresis of virion RNA under denaturing conditions demonstrated that dense, major-component, and light HAV particles all contained RNA of similar length. Thus, infectious HAV particles released by BS-C-1 cells in vitro consist of three distinct types which band at substantially different densities in CsC1, suggesting different capsid structures with varied permeability to cesium or different degrees of hydration. Images PMID:2983123

  2. Petrochronological and structural arguments for upper plate thickening and relamination of the lower plate buoyant material in the Variscan Bohemian Massif

    NASA Astrophysics Data System (ADS)

    Peřestý, Vít; Holder, Robert; Lexa, Ondrej; Racek, Martin; Jeřábek, Petr

    2014-05-01

    Recent tectonic models for the Variscan evolution of the Bohemian Massif emphasize the role of Rayleigh-Taylor instability for the 355-340 Ma evolution of the Moldanubian domain. This model is based on the presence of weak, low-density felsic material tectonically underplating a high-density mafic layer and its subsequent gravity-driven overturn. However, earlier phases of the Variscan orogeny concerning the emplacement of felsic low-density material to the base of the upper plate are so far poorly documented. We contribute to this problem by deciphering of polyphase early-Variscan (~375 Ma) deformation and metamorphism close to the main Variscan suture. Detailed structural, pseudosection and microstructural analyses combined with LASS monazite dating were carried out in metapelites along the western margin of the upper plate represented by the Teplá Crystalline Complex (TCC). This region is represented by a ~25 km wide deformation zone with E-W metamorphic gradients associated with two distinct early-Variscan events (~380-375 and ~375-370 Ma). The first compressional event produced a vertical NNE-SSW trending fabric and a continuous and prograde Barrovian metamorphic sequence ranging from biotite to kyanite zones at a field geotherm of 20 to 25 °C/km. Subsequently, a gently SE dipping normal shear-zone associated with retrogression develops along the base of the TCC. This sub-horizontal fabric shows normal metamorphic zonation ranging from sillimanite, biotite to chlorite zones and indicates vertical shortening related to unroofing of high pressure metabasites of the underlying Mariánské-Lázně Complex. The first metamorphic fabric is interpreted to result from early thickening of the upper plate during continental underthrusting of Saxothuringian continent (380 to 375 Ma) while the second deformation and metamorphism (~370 Ma) reflects vertical shortening produced by buoyant uplift of accreted Saxothuringian felsic crust. This event is the unique yet

  3. The influence of buoyant forces and volume fraction of particles on the particle pushing/entrapment transition during directional solidification of Al/SiC and Al/graphite composites

    NASA Technical Reports Server (NTRS)

    Stefanescu, Doru M.; Moitra, Avijit; Kacar, A. Sedat; Dhindaw, Brij K.

    1990-01-01

    Directional solidification experiments in a Bridgman-type furnace were used to study particle behavior at the liquid/solid interface in aluminum metal matrix composites. Graphite or silicon-carbide particles were first dispersed in aluminum-base alloys via a mechanically stirred vortex. Then, 100-mm-diameter and 120-mm-long samples were cast in steel dies and used for directional solidification. The processing variables controlled were the direction and velocity of solidification and the temperature gradient at the interface. The material variables monitored were the interface energy, the liquid/particle density difference, the particle/liquid thermal conductivity ratio, and the volume fraction of particles. These properties were changed by selecting combinations of particles (graphite or silicon carbide) and alloys (Al-Cu, Al-Mg, Al-Ni). A model which consideres process thermodynamics, process kinetics (including the role of buoyant forces), and thermophysical properties was developed. Based on solidification direction and velocity, and on materials properties, four types of behavior were predicted. Sessile drop experiments were also used to determine some of the interface energies required in calculation with the proposed model. Experimental results compared favorably with model predictions.

  4. The influence of buoyant forces and volume fraction of particles on the particle pushing/entrapment transition during directional solidification of Al/SiC and Al/graphite composites

    NASA Astrophysics Data System (ADS)

    Stefanescu, Doru M.; Moitra, Avijit; Kacar, A. Sedat; Dhindaw, Brij K.

    1990-01-01

    Directional solidification experiments in a Bridgman-type furnace were used to study particle behavior at the liquid/solid interface in aluminum metal matrix composites. Graphite or siliconcarbide particles were first dispersed in aluminum-base alloys via a mechanically stirred vortex. Then, 100-mm-diameter and 120-mm-long samples were cast in steel dies and used for directional solidification. The processing variables controlled were the direction and velocity of solidification and the temperature gradient at the interface. The material variables monitored were the interface energy, the liquid/particle density difference, the particle/liquid thermal conductivity ratio, and the volume fraction of particles. These properties were changed by selecting combinations of particles (graphite or silicon carbide) and alloys (Al-Cu, Al-Mg, Al-Ni). A model which considers process thermodynamics, process kinetics (including the role of buoyant forces), and thermophysical properties was developed. Based on solidification direction and velocity, and on materials properties, four types of behavior were predicted. Sessile drop experiments were also used to determine some of the interface energies required in calculation with the proposed model. Experimental results compared favorably with model predictions.

  5. Buoyant Rover for Under-Ice Exploration

    NASA Astrophysics Data System (ADS)

    Berisford, D. F.; Leichty, J. M.; Klesh, A. T.; Matthews, J. B.; Hand, K. P.

    2012-12-01

    We have designed, constructed and tested a prototype robotic mobility platform for exploring the underside of ice sheets in frozen lake or ocean environments. The ice-water interface often provides some of the most interesting and dynamic chemistry in partially frozen systems, as dissolved impurities are rejected from the advancing freezing front. Higher concentrations of microorganisms can be found in this region, and the topography of the ice underside can help reveal the history of its formation. Furthermore, in lake environments ice cover can serve to trap gases released from biological and geological processes in the subsurface. The rover uses a two-wheeled design with a flexible dragging tail, enabling it to fit into a 10-inch diameter ice borehole. The sealed air-filled cylindrical body, along with closed-cell foam inside of cone-shaped wheels, provides buoyancy force to enable roving along the underside of the ice. The prototype contains two cameras that stream live video via a tethered connection to a ground station and uses semi-autonomous control via a PC. Preliminary testing of the prototype in a cold lab and in northern Alaskan thermokarst lakes demonstrates the utility and simplicity of this type of robotic platform for exploring the ice-water interface. This technology has potential future use in landed missions to icy ocean worlds in the solar system.

  6. Buoyant miscible displacement flows in vertical pipe

    NASA Astrophysics Data System (ADS)

    Amiri, A.; Larachi, F.; Taghavi, S. M.

    2016-10-01

    The displacement flow of two miscible Newtonian fluids is investigated experimentally in a vertical pipe of long aspect ratio (δ-1 ≈ 210). The fluids have a small density difference and they have the same viscosity. The heavy displacing fluid is initially placed above the light displaced fluid. The displacement flow is downwards. The experiments cover a wide range of the two dimensionless parameters that largely describe the flow: the modified Reynolds number (0 ≤ Ret⪅800) and the densimetric Froude number (0 ≤ Fr ≤ 24). We report on the stabilizing effect of the imposed flow and uncover the existence of two main flow regimes at long times: a stable displacement flow and an unstable displacement flow. The transition between the two regimes occurs at a critical modified Reynolds number " separators=" R et | Critical , as a function of Fr. We study in depth the stable flow regime: First, a lubrication model combined with a simple initial acceleration formulation delivers a reasonable prediction to the time-dependent penetrating displacing front velocity. Second, we find two sub-regimes for stable displacements, namely, sustained-back-flows and no-sustained-back-flows. The transition between the two sub-regimes is a marginal stationary interface flow state, which is also well predicted by the lubrication model. The unstable regime is associated to instabilities and diffusive features of the flow. In addition, particular patterns such as front detachment phenomenon appear in the unstable flow regime, for which we quantify the regions of existence versus the dimensionless groups.

  7. Transport and Diffusion of Buoyant Material.

    DTIC Science & Technology

    1983-05-01

    highest particles, XBAR and YBAR are the mean X and Y positions in each layer, and XSIG and YSIG are the respective standard deviations. The radiation...X, Y ) will not lose any heat by entrainment. Nine-tenths of AT is lost in the "fully" entrained region (for example, where ke = 0.9 and Y > Y + ay...conditions. The X, Z view is shown ........................... ................... 24 8. Output as in figure 4, but showing the Y , Z view..................25

  8. Candle Flames in Non-Buoyant Atmospheres

    NASA Technical Reports Server (NTRS)

    Dietrich, D. L.; Ross, H. D.; Shu, Y.; Tien, J. S.

    1999-01-01

    This paper addresses the behavior of a candle flame in a long-duration, quiescent microgravity environment both on the space Shuttle and the Mir Orbiting Station (OS). On the Shuttle, the flames became dim blue after an initial transient where there was significant yellow (presumably soot) in the flame. The flame lifetimes were typically less than 60 seconds. The safety-mandated candlebox that contained the candle flame inhibited oxygen transport to the flame and thus limited the flame lifetime. 'Me flames on the Mir OS were similar, except that the yellow luminosity persisted longer into the flame lifetime because of a higher initial oxygen concentration. The Mir flames burned for as long as 45 minutes. The difference in the flame lifetime between the Shuttle and Mir flames was primarily the redesigned candlebox that did not inhibit oxygen transport to the flame. In both environments, the flame intensity and the height-to-width ratio gradually decreased as the ambient oxygen content in the sealed chamber slowly decreased. Both sets of experiments showed spontaneous, axisymmetric flame oscillations just prior to extinction. The paper also presents a numerical model of candle flame. The model is detailed in the gas-phase, but uses a simplified liquid/wick phase. 'Me model predicts a steady flame with a shape and size quantitatively similar to the Shuttle and Mir flames. ne model also predicts pre-extinction flame oscillations if the decrease in ambient oxygen is small enough.

  9. Candle Flames in Non-Buoyant Atmospheres

    NASA Technical Reports Server (NTRS)

    Dietrich, D. L.; Ross, H. D.; Shu, Y.; Chang, P.; Tien, J. S.

    2000-01-01

    This paper addresses the behavior of a candle flame in a long-duration, quiescent microgravity environment both on the space Shuttle and the Mir Orbiting Station. On the Shuttle, the flames became dim blue after an initial transient where there was significant yellow (presumably soot) in the flame. The flame lifetimes were typically less than 60 seconds. The safety-mandated candlebox that contained the candle flame inhibited oxygen transport to the flame and thus limited the flame lifetime. The flames on the Mir were similar, except that the yellow luminosity persisted longer into the flame lifetime because of a higher initial oxygen concentration, The Mir flames burned for as long as 45 minutes. The difference in the flame lifetime between the Shuttle and Mir flames was primarily the redesigned candlebox that did not inhibit oxygen transport to the flame. In both environments, the flame intensity and the height-to-width ratio gradually decreased as the ambient oxygen content in the sealed chamber slowly decreased. Both sets of experiments showed spontaneous, axisymmetric flame oscillations just prior to extinction. The paper also presents a numerical model of a candle flame. The formulation is two-dimensional and time-dependent in the gas phase with constant specific heats, thermal conductivity and Lewis number (although different species can have different Lewis numbers), one-step finite-rate kinetics, and gas-phase radiative losses from CO2 and H2O. The treatment of the liquid/wick phase assumes that the, fuel evaporates from a constant diameter sphere connected to an inert cone. The model predicts a steady flame with a shape and size quantitatively similar to the Shuttle and Mir flames. The computation predicts that the flame size will increase slightly with increasing ambient oxygen mole fraction. The model also predicts pre-extinction flame oscillations if the rate of decrease in ambient oxygen is small enough, such as that which would occur for a flame burning in a sealed ambient.

  10. A modeling of buoyant gas plume migration

    SciTech Connect

    Silin, D.; Patzek, T.; Benson, S.M.

    2008-12-01

    This work is motivated by the growing interest in injecting carbon dioxide into deep geological formations as a means of avoiding its atmospheric emissions and consequent global warming. Ideally, the injected greenhouse gas stays in the injection zone for a geologic time, eventually dissolves in the formation brine and remains trapped by mineralization. However, one of the potential problems associated with the geologic method of sequestration is that naturally present or inadvertently created conduits in the cap rock may result in a gas leakage from primary storage. Even in a supercritical state, the carbon dioxide viscosity and density are lower than those of the formation brine. Buoyancy tends to drive the leaked CO{sub 2} plume upward. Theoretical and experimental studies of buoyancy-driven supercritical CO{sub 2} flow, including estimation of time scales associated with plume evolution and migration, are critical for developing technology, monitoring policy, and regulations for safe carbon dioxide geologic sequestration. In this study, we obtain simple estimates of vertical plume propagation velocity taking into account the density and viscosity contrast between CO{sub 2} and brine. We describe buoyancy-driven countercurrent flow of two immiscible phases by a Buckley-Leverett type model. The model predicts that a plume of supercritical carbon dioxide in a homogeneous water-saturated porous medium does not migrate upward like a bubble in bulk water. Rather, it spreads upward until it reaches a seal or until it becomes immobile. A simple formula requiring no complex numerical calculations describes the velocity of plume propagation. This solution is a simplification of a more comprehensive theory of countercurrent plume migration (Silin et al., 2007). In a layered reservoir, the simplified solution predicts a slower plume front propagation relative to a homogeneous formation with the same harmonic mean permeability. In contrast, the model yields much higher plume propagation estimates in a high-permeability conduit like a vertical fracture.

  11. Reconfigurable Buoyant Cable Antenna with Improved Gain

    DTIC Science & Technology

    2010-07-28

    consists of a number of connected streamer cable sections, which each comprise a mechanical jacket surrounding a hollow core enclosing seismic sensor and...of insulation. A buoyancy layer/ jacket is either injection molded or extruded in place onto the core to make the final structure a solid object...systems: [0008] U.S. Patent No. 5,745,436, issued April 28, 1998, to Bittleston, discloses a semi-dry marine seismic streamer cable that

  12. JBFA-Buoyant Flight, Special Edition

    NASA Technical Reports Server (NTRS)

    Wada, C.; Terada, K.; Ishii, C.; Nagamatsu, K.; Makino, M.; Ichiyoshi, S.

    1982-01-01

    Progress in the project to traverse the Pacific Ocean by manned balloon is summarized. The development of a hybrid lighter than aircraft combining the buoyancy of a gas bag with the vertical lift off capabilities of the helicopter is also addressed.

  13. Continents as lithological icebergs: The importance of buoyant lithospheric roots

    USGS Publications Warehouse

    Abbott, D.H.; Drury, R.; Mooney, W.D.

    1997-01-01

    An understanding of the formation of new continental crust provides an important guide to locating the oldest terrestrial rocks and minerals. We evaluated the crustal thicknesses of the thinnest stable continental crust and of an unsubductable oceanic plateau and used the resulting data to estimate the amount of mantle melting which produces permanent continental crust. The lithospheric mantle is sufficiently depleted to produce permanent buoyancy (i.e., the crust is unsubductable) at crustal thicknesses greater than 25-27 km. These unsubductable oceanic plateaus and hotspot island chains are important sources of new continental crust. The newest continental crust (e.g., the Ontong Java plateau) has a basaltic composition, not a granitic one. The observed structure and geochemistry of continents are the result of convergent margin magmatism and metamorphism which modify the nascent basaltic crust into a lowermost basaltic layer overlain by a more silicic upper crust. The definition of a continent should imply only that the lithosphere is unsubductable over ??? 0.25 Ga time periods. Therefore, the search for the oldest crustal rocks should include rocks from lower to mid-crustal levels.

  14. Effects of Submesoscale Ocean Turbulence on Buoyant and Passive Tracers

    NASA Astrophysics Data System (ADS)

    Smith, K.; Fox-Kemper, B.; Hamlington, P.

    2015-12-01

    Recent studies have shown that submesoscale processes greatly influence the dynamics and structure of the oceanic mixed layer. These processes have a substantial impact, in particular, on the transport of momentum, buoyancy, and passive tracers such as carbonate chemical species, nutrients, and plankton. It has been suggested that the vertical transfer of both active buoyancy and passive tracers can be described by the same vertical flux profile, thus permitting the use of one flux profile when parameterizing the effects of submoescale processes on tracer transport. Within the submesoscale range, however, both partly geostrophic fronts and eddies, which act to restratify the mixed layer, and small-scale three-dimensional turbulence, which acts to enhance vertical mixing, are simultaneously active, thus giving rise to complex multiscale interactions between turbulence and tracer dynamics. In this talk, large eddy simulations spanning the range of scales from 20km down to 5m are used to examine the role of multiscale turbulent mixing on both an active buoyancy tracer and several nonreactive passive ocean tracers from interior and sea-surface sources. The simulations include the effects of both small-scale wave-driven Langmuir turbulence and larger submesoscale eddies. Tracer properties are characterized using spatial fields and statistics, multiscale fluxes, and spectra. Results show that while submesoscale eddies transport buoyancy upward to extract potential energy, the same is not true of passive tracers. Instead, the suppression of turbulent vertical mixing in active submesoscale regions leads to suppressed entrainment of tracers, implying weaker transport by submesoscale activity. These results along with implications for the development of reduced order tracer models will be discussed.

  15. Interaction between a vertical turbulent buoyant jet and a thermocline

    NASA Astrophysics Data System (ADS)

    Ezhova, Ekaterina; Brandt, Luca; Cenedese, Claudia

    2016-11-01

    We study the behaviour of an axisymmetric vertical turbulent jet in an unconfined stratified environment by means of well-resolved large eddy simulations (LES). The stratification is two layers separated by a thermocline and the thermocline thickness considered is smaller and on the order of the jet diameter at the thermocline entrance. We quantify mean jet penetration, stratified turbulent entrainment and study the generation of internal waves. The mean jet penetration is predicted based on the conservation of the source energy in the thermocline. The entrainment coefficient for the thin thermocline agrees with the theoretical model for a two-layer stratification with a sharp interface. A secondary flow towards the jet top appears in the upper part of the thick thermocline. The jet generates internal waves at frequencies in agreement with similar experiments. We shall also report the results of LES of a turbulent plume in a stratified fluid modelling subglacial discharge from a submarine glacier in stratifications typical of Greenland fjords. We consider a free plume from a round source of various diameters with double the total discharge estimated from the field data. We quantify plume dynamics and compare the results for plumes and jets. E. Ezhova acknowledges VR Swedish Research Council. The authors acknowledge computer time provided by SNIC (Swedish National Infrastructure for Computing).

  16. Countering Solutal Buoyant Convection with High Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Leslie, F. W.

    2002-01-01

    An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular crystals for diffraction analyses has been the central focus for biochemist, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitant, other possible phases of the protein, foreign particles, the walls of the container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and sedimentation, as is achieved in microgravity, we have been able to dramatically effect the movement and distribution of macromolecules in the fluid, and thus their transport, formation of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. We postulate that limited convection in a magnetic field will provide the environment for the growth of high quality crystals. The approach exploits the variation of fluid magnetic susceptibility with concentration for this purpose and the convective damping is realized by appropriately positioning the crystal growth cell so that the magnetic susceptibility force counteracts terrestrial gravity. The general objective is to test the hypothesis of convective control using a strong magnetic field and magnetic field gradient and to understand the nature of the various forces that come into play. Specifically we aim to delineate causative factors and to quantify them through experiments, analysis and numerical modeling. The paper will report on the current status of the investigation and discuss results from the experimental and modeling efforts.

  17. Time-dependent buoyant puff model for explosive sources

    SciTech Connect

    Kansa, E.J.

    1997-10-01

    This paper presents a new model for explosive puff rise histories that is derived from the strong conservative form of the partial differential equations of mass, momenta, and total energy that are integrated over space to yield a coupled system of time dependent nonlinear ordinary differential equations (ODEs). By allowing the dimensions of the puff to evolve laterally and horizontally, the initial rising spherical shaped puff evolves into a rising ellipsoidal shaped mushroom cloud. This model treats the turbulence that is generated by the puff itself and the ambient atmospheric turbulence as separate mechanisms in determining the puff history. The puff rise history was found to depend not only upon the mass and initial temperature of the explosion, but also upon the local stability conditions of the ambient atmosphere through which the puff rises. This model was calibrated by comparison with the Roller Coaster experiments, ranging from unstable to very stable atmospheric conditions; the agreement of the model history curves with these experimental curves was within 10%.

  18. Time-dependent buoyant puff model for explosive sources

    SciTech Connect

    Kansa, E.J.

    1997-01-01

    Several models exist to predict the time dependent behavior of bouyant puffs that result from explosions. This paper presents a new model that is derived from the strong conservative form of the conservation partial differential equations that are integrated over space to yield a coupled system of time dependent nonlinear ordinary differential equations. This model permits the cloud to evolve from an intial spherical shape not an ellipsoidal shape. It ignores the Boussinesq approximation, and treats the turbulence that is generated by the puff itself and the ambient atmospheric tubulence as separate mechanisms in determining the puff history. The puff cloud rise history was found to depend no only on the mass and initial temperature of the explosion, but also upon the stability conditions of the ambient atmosphere. This model was calibrated by comparison with the Roller Coaster experiments.

  19. Civil markets for buoyant heavy-lift vehicles

    NASA Technical Reports Server (NTRS)

    Mettam, P. J.; Hansen, D.; Ardema, M. D.

    1981-01-01

    Worldwide civil markets for heavy lift airships were investigated. Substantial potential market demand was identified for payloads of from 13 to 800 tons. The largest markets appear to be in applications to relieve port congestion, construction of power generating plants, and, most notably, logging. Because of significant uncertainties both in vehicle and market characteristics, further analysis will be necessary to verify the identified market potential of heavy lift airship concepts.

  20. Buoyant Low Stretch Diffusion Flames Beneath Cylindrical PMMA Samples

    NASA Technical Reports Server (NTRS)

    Olson, S. L.; Tien, J. S.

    1999-01-01

    A unique new way to study low gravity flames in normal gravity has been developed. To study flame structure and extinction characteristics in low stretch environments, a normal gravity low-stretch diffusion flame is generated using a cylindrical PMMA sample of varying large radii. Burning rates, visible flame thickness, visible flame standoff distance, temperature profiles in the solid and gas, and radiative loss from the system were measured. A transition from the blowoff side of the flammability map to the quenching side of the flammability map is observed at approximately 6-7/ sec, as determined by curvefits to the non-monotonic trends in peak temperatures, solid and gas-phase temperature gradients, and non-dimensional standoff distances. A surface energy balance reveals that the fraction of heat transfer from the flame that is lost to in-depth conduction and surface radiation increases with decreasing stretch until quenching extinction is observed. This is primarily due to decreased heat transfer from the flame, while the magnitude of the losses remains the same. A unique local extinction flamelet phenomena and associated pre-extinction oscillations are observed at very low stretch. An ultimate quenching extinction limit is found at low stretch with sufficiently high induced heat losses.

  1. Buoyant vortex rings and knots with thin core

    NASA Astrophysics Data System (ADS)

    Chang, Ching; Llewellyn Smith, Stefan

    2016-11-01

    One challenge of studying the motion of vortex filaments arises from the singular nature of the Biot-Savart integral. We employ the momentum balance investigated by Moore and Saffman for thin-core vortex filaments to obtain the self-induced velocity of filaments, rings and knots. A key feature of the approach is the possibility of incorporating buoyancy forces. The numerical scheme used is discussed and compared to previous analytical and numerical results in the literature. The effect of geometry and buoyancy on the motion of such vortices is examined.

  2. Buoyant Outflows in the Presence of Ccomplex Topography

    DTIC Science & Technology

    2010-09-30

    Balopoulos, 1999. Climatic changes in the Aegean Sea influence the eastern Mediterranean thermohaline circulation (1986– 1997). Geophys. Res. Lett...Georgopoulos and P. G. Drakopoulos, 2000. The role of the North Aegean in triggering the recent Eastern Mediterranean climate changes . J. Geophys. Res., 105...if the inter-annual variability of the Dardanelles plume (in the context of changing outflow properties and regional atmospheric forcing) is related

  3. Dynamic Stability of Positively Buoyant Submersibles: Vertical Plane Solutions

    DTIC Science & Technology

    1991-12-01

    7 b. Longitudunal Center of Buoyancy, xGB...........8 C. Vertical Center of Buoyancy, zGB .......................*’**"*8 2. Assumed...Variations in the Amount of Excess Buoyancy (bB) ..................... 52 3. Variations in Vertical Center of Gravity ( ZGB ) ........................... 57 4...56 20. Stable Surge Velocity (u) Solutions for Variations in ZGB ...................... 57 21. Stable Heave Velocity (w) Solutions for

  4. PIV Measurements in Weakly Buoyant Gas Jet Flames

    NASA Technical Reports Server (NTRS)

    Sunderland, Peter B.; Greenbberg, Paul S.; Urban, David L.; Wernet, Mark P.; Yanis, William

    2001-01-01

    Despite numerous experimental investigations, the characterization of microgravity laminar jet diffusion flames remains incomplete. Measurements to date have included shapes, temperatures, soot properties, radiative emissions and compositions, but full-field quantitative measurements of velocity are lacking. Since the differences between normal-gravity and microgravity diffusion flames are fundamentally influenced by changes in velocities, it is imperative that the associated velocity fields be measured in microgravity flames. Velocity measurements in nonbuoyant flames will be helpful both in validating numerical models and in interpreting past microgravity combustion experiments. Pointwise velocity techniques are inadequate for full-field velocity measurements in microgravity facilities. In contrast, Particle Image Velocimetry (PIV) can capture the entire flow field in less than 1% of the time required with Laser Doppler Velocimetry (LDV). Although PIV is a mature diagnostic for normal-gravity flames , restrictions on size, power and data storage complicate these measurements in microgravity. Results from the application of PIV to gas jet flames in normal gravity are presented here. Ethane flames burning at 13, 25 and 50 kPa are considered. These results are presented in more detail in Wernet et al. (2000). The PIV system developed for these measurements recently has been adapted for on-rig use in the NASA Glenn 2.2-second drop tower.

  5. Characterization of Horizontally-Issuing Reacting Buoyant Jets

    DTIC Science & Technology

    2011-03-01

    while the vertical arrow pointing upwards corresponds to their excitation to a state of higher energy. One interesting concept not conveyed in Figure 9...the purposes of this research, the Q1(6) rotational state was excited , which corresponds to an excitement wavelength of 282.9 nm. Figure 10. An...speaking, quenching prevents the release of a fluorescent signal in one of three different ways. When quenching occurs, molecules excited to a higher

  6. Filtered Rayleigh Scattering Measurements in a Buoyant Flowfield

    DTIC Science & Technology

    2007-03-01

    is presented in Figure 32 and Figure 33. The sampli rate is 6.5 Hz with an exposure time of 50 ms. The downstream location is 0.8 inches (x/d = 3.1...FRS signal can be collected using a 10 m manufacturer suggests a sampli A 50 ms exposure time is chosen in this res of processing the data and is a

  7. Locomotion of neutrally buoyant fish with flexible caudal fin.

    PubMed

    Iosilevskii, Gil

    2016-06-21

    Historically, burst-and-coast locomotion strategies have been given two very different explanations. The first one was based on the assumption that the drag of an actively swimming fish is greater than the drag of the same fish in motionless glide. Fish reduce the cost of locomotion by swimming actively during a part of the swimming interval, and gliding through the remaining part. The second one was based on the assumption that muscles perform efficiently only if their contraction rate exceeds a certain threshold. Fish reduce the cost of locomotion by using an efficient contraction rate during a part of the swimming interval, and gliding through the remaining part. In this paper, we suggest yet a third explanation. It is based on the assumption that propulsion efficiency of a swimmer can increase with thrust. Fish reduce the cost of locomotion by alternating high thrust, and hence more efficient, bursts with passive glides. The paper presents a formal analysis of the respective burst-and-coast strategy, shows that the locomotion efficiency can be practically as high as the propulsion efficiency during burst, and shows that the other two explanations can be considered particular cases of the present one.

  8. Interaction between a large buoyant bubble and turbulence

    NASA Astrophysics Data System (ADS)

    Loisy, Aurore; Naso, Aurore

    2017-01-01

    The free rise of isolated, deformable, finite-size bubbles in otherwise homogeneous isotropic turbulence is investigated by direct numerical simulation. The Navier-Stokes equations are solved in both phases subject to the pertinent velocity and stress conditions at the deformable gas-liquid interface. The bubble rise velocity is found to be drastically reduced by turbulence, as is widely known for microbubbles. The probability distribution functions of the horizontal bubble acceleration component are well fitted by a log-normal distribution. The distributions of the vertical components are negatively skewed, a property related to the fact that bubbles experience on average stronger decelerations than accelerations. An assessment of the correlations of bubble acceleration with properties of the surrounding flow is used to define estimates of the liquid velocity and vorticity entering in liquid acceleration and lift forces. Finally, fast rising bubbles are found to preferentially sample downflow regions of the flow, whereas those subjected to a higher turbulence level have an increased residence time in swirling regions, some features similar to those of small bubbles.

  9. Second order closure modeling of turbulent buoyant wall plumes

    NASA Technical Reports Server (NTRS)

    Zhu, Gang; Lai, Ming-Chia; Shih, Tsan-Hsing

    1992-01-01

    Non-intrusive measurements of scalar and momentum transport in turbulent wall plumes, using a combined technique of laser Doppler anemometry and laser-induced fluorescence, has shown some interesting features not present in the free jet or plumes. First, buoyancy-generation of turbulence is shown to be important throughout the flow field. Combined with low-Reynolds-number turbulence and near-wall effect, this may raise the anisotropic turbulence structure beyond the prediction of eddy-viscosity models. Second, the transverse scalar fluxes do not correspond only to the mean scalar gradients, as would be expected from gradient-diffusion modeling. Third, higher-order velocity-scalar correlations which describe turbulent transport phenomena could not be predicted using simple turbulence models. A second-order closure simulation of turbulent adiabatic wall plumes, taking into account the recent progress in scalar transport, near-wall effect and buoyancy, is reported in the current study to compare with the non-intrusive measurements. In spite of the small velocity scale of the wall plumes, the results showed that low-Reynolds-number correction is not critically important to predict the adiabatic cases tested and cannot be applied beyond the maximum velocity location. The mean and turbulent velocity profiles are very closely predicted by the second-order closure models. but the scalar field is less satisfactory, with the scalar fluctuation level underpredicted. Strong intermittency of the low-Reynolds-number flow field is suspected of these discrepancies. The trends in second- and third-order velocity-scalar correlations, which describe turbulent transport phenomena, are also predicted in general, with the cross-streamwise correlations better than the streamwise one. Buoyancy terms modeling the pressure-correlation are shown to improve the prediction slightly. The effects of equilibrium time-scale ratio and boundary condition are also discussed.

  10. A Test Fixture for Detecting the Presence of Water in Buoyant Cables

    DTIC Science & Technology

    1990-06-14

    Rodriguez Submarine Electromagnetic Systems Department DTIC ELECTFF MAY 2 7 1993,A Naval Underwater Systems Center New London, Connecticut / Newport, Rhode...Investigator C.E. Odams. The NUSC Program Manager is A.R. Susi, Code 34292. The spcisoring activity is SPAWAR PMW- 153-2; Project Manager Michael Sheehan... Systems Branch, along with Messrs. Craig L. Flynn, Eric von Winkle and Phillip Watrous of the Pressure Lab for their assistance in the measurements

  11. Approximate Value of Buoyant Force: A Water-Filled Balloon Demonstration

    ERIC Educational Resources Information Center

    Radovanovic, Jelena; Slisko, Josip

    2012-01-01

    Floating and sinking might be common phenomena, encountered on a daily basis, but still represent conceptually complex scientific topics. Research has shown that most students have certain experiences and their own "theories" that explain why objects sink or float. Unfortunately, many of these "theories" are either misconceptions or are valid only…

  12. Time Resolved Filtered Rayleigh Scattering Measurement of a Centrifugally Loaded Buoyant Jet

    DTIC Science & Technology

    2011-03-01

    filter along with the transmitted Rayleigh scattering signal [8]. In their study on atomic and molecular notch filters, Miles et al. present...light (broadened and shifted) fell outside the absorption well of the filter while ensuring near total absorbtion of the incident signal itself...Yalin, A.P, Tang, Z, Zaidi, S. H, and Forkey, J.N., “Flow Field Imaging through Sharp-edged Atomic and Molecular ‘Notch’ Filters ”, Measurement

  13. Preventing Buoyant Displacement Gas Release Events in Hanford Double-Shell Waste Tanks

    SciTech Connect

    Meyer, Perry A.; Stewart, Charles W.

    2001-01-01

    This report summarizes the predictive methods used to ensure that waste transfer operations in Hanford waste tanks do not create waste configurations that lead to unsafe gas release events. The gas release behavior of the waste in existing double-shell tanks has been well characterized, and the flammable gas safety issues associated with safe storage of waste in the current configuration are being formally resolved. However, waste is also being transferred between double-shell tanks and from single-shell tanks into double-shell tanks by saltwell pumping and sluicing that create new wastes and waste configurations that have not been studied as well. Additionally, planning is underway for various waste transfer scenarios to support waste feed delivery to the proposed vitrification plant. It is critical that such waste transfers do not create waste conditions with the potential for dangerous gas release events.

  14. Evidence that platelet buoyant density, but not size, correlates with platelet age in man.

    PubMed

    Mezzano, D; Hwang, K; Catalano, P; Aster, R H

    1981-01-01

    Following infusion of 51Cr-labeled autologous platelets into normal subjects, high-density (HD) and low-density (LD) platelet cohorts were isolated by prolonged centrifugation in isosmotic arabino-galactan (Stractan). Specific radio-activity of LD platelets declined rapidly post-infusion (T1/2 = 1.5 days), but specific radioactivity of HD platelets remained constant or increased over a 3--4-day period and gradually declined for 6--7 days thereafter. These differences were exaggerated when platelet cohorts enriched in LD or HD cells by slow centrifugation in high-density albumin were labeled and transfused. Mean survival of a platelet cohort enriched with HD cells was significantly (P less than 0.02) shorter (7.73 days) than that of a cohort enriched with LD cells (9.33) days). In normal subjects treated with aspirin, capacity for thromboxane synthesis was regained more rapidly (P less than 0.05) in LD than in HD platelets. HD and LD platelets differed only slightly in mean volume (HD platelets = 7.57 mu3, LD platelets = 6.87 mu3, 0.05 less than P less than 0.01). We believe the most logical interpretation of these findings is that under normal conditions in man, newly formed platelets are less dense on the average than total platelets and become more dense as they age in the circulation. Thus, specific radioactivity of LD platelets declines rapidly as these platelets move into a more dense compartment and are replaced by newly formed, unlabelled cells; specific radioactivity of HD platelets remains constant or increases as labelled platelets enter this compartment in numbers equal to or greater than the number leaving it at the end of their life span. The similarity in mean volumes of LD and HD platelets suggests that platelet size is unrelated to platelet age under normal conditions.

  15. Evidence that platelet buoyant density, but not size, correlates with platelet age in man

    SciTech Connect

    Mezzano, D.; Hwang, K.; Catalano, P.; Aster, R.H.

    1981-01-01

    Following infusion of 51Cr-labeled autologous platelets into normal subjects, high-density (HD) and low-density (LD) platelet cohorts were isolated by prolonged centrifugation in isosmotic arabino-galactan (Stractan). Specific radio-activity of LD platelets declined rapidly post-infusion (T1/2 . 1.5 days), but specific radioactivity of HD platelets remained constant or increased over a 3--4-day period and gradually declined for 6--7 days thereafter. These differences were exaggerated when platelet cohorts enriched in LD or HD cells by slow centrifugation in high-density albumin were labeled and transfused. Mean survival of a platelet cohort enriched with HD cells was significantly (P less than 0.02) shorter (7.73 days) than that of a cohort enriched with LD cells (9.33) days). In normal subjects treated with aspirin, capacity for thromboxane synthesis was regained more rapidly (P less than 0.05) in LD than in HD platelets. HD and LD platelets differed only slightly in mean volume (HD platelets . 7.57 mu3, LD platelets . 6.87 mu3, 0.05 less than P less than 0.01). We believe the most logical interpretation of these findings is that under normal conditions in man, newly formed platelets are less dense on the average than total platelets and become more dense as they age in the circulation. Thus, specific radioactivity of LD platelets declines rapidly as these platelets move into a more dense compartment and are replaced by newly formed, unlabelled cells; specific radioactivity of HD platelets remains constant or increases as labelled platelets enter this compartment in numbers equal to or greater than the number leaving it at the end of their life span. The similarity in mean volumes of LD and HD platelets suggests that platelet size is unrelated to platelet age under normal conditions.

  16. Increased methane emissions from deep osmotic and buoyant convection beneath submarine seeps as climate warms.

    PubMed

    Cardoso, Silvana S S; Cartwright, Julyan H E

    2016-10-27

    High speeds have been measured at seep and mud-volcano sites expelling methane-rich fluids from the seabed. Thermal or solute-driven convection alone cannot explain such high velocities in low-permeability sediments. Here we demonstrate that in addition to buoyancy, osmotic effects generated by the adsorption of methane onto the sediments can create large overpressures, capable of recirculating seawater from the seafloor to depth in the sediment layer, then expelling it upwards at rates of up to a few hundreds of metres per year. In the presence of global warming, such deep recirculation of seawater can accelerate the melting of methane hydrates at depth from timescales of millennia to just decades, and can drastically increase the rate of release of methane into the hydrosphere and perhaps the atmosphere.

  17. Increased methane emissions from deep osmotic and buoyant convection beneath submarine seeps as climate warms

    NASA Astrophysics Data System (ADS)

    Cardoso, Silvana S. S.; Cartwright, Julyan H. E.

    2016-10-01

    High speeds have been measured at seep and mud-volcano sites expelling methane-rich fluids from the seabed. Thermal or solute-driven convection alone cannot explain such high velocities in low-permeability sediments. Here we demonstrate that in addition to buoyancy, osmotic effects generated by the adsorption of methane onto the sediments can create large overpressures, capable of recirculating seawater from the seafloor to depth in the sediment layer, then expelling it upwards at rates of up to a few hundreds of metres per year. In the presence of global warming, such deep recirculation of seawater can accelerate the melting of methane hydrates at depth from timescales of millennia to just decades, and can drastically increase the rate of release of methane into the hydrosphere and perhaps the atmosphere.

  18. Design and Construction of a Computer Controlled Mirothermocouple Probe for the Study of Buoyant Jets.

    DTIC Science & Technology

    1984-09-01

    APPENDIX D: TABULATED DATA------------------------------- 107 1. ROTOMETER CALIBRATION------------------- 107 2. TEST RESULTS...41 7 23. Nozzle Thermocouple Grounding Arrangement -------- 42 24. Probe Design Test Panel -------------------------- 45...TFIT found in Appendix C. 43 3. Probe As the probe assembly was being developed, it was convenient to test its suitability with the probe calibration

  19. NMR imaging and hydrodynamic analysis of neutrally buoyant non-Newtonian slurry flows

    SciTech Connect

    Bouillard, J.X.; Sinton, S.W.

    1995-02-01

    The flow of solids loaded suspension in cylindrical pipes has been the object of intense experimental and theoretical investigations in recent years. These types of flows are of great interest in chemical engineering because of their important use in many industrial manufacturing processes. Such flows are for example encountered in the manufacture of solid-rocket propellants, advanced ceramics, reinforced polymer composites, in heterogenous catalytic reactors, and in the pipeline transport of liquid-solids suspensions. In most cases, the suspension microstructure and the degree of solids dispersion greatly affect the final performance of the manufactured product. For example, solid propellant pellets need to be extremely-well dispersed in gel matrices for use as rocket engine solid fuels. The homogeneity of pellet dispersion is critical to allow good uniformity of the burn rate, which in turn affects the final mechanical performance of the engine. Today`s manufacturing of such fuels uses continuous flow processes rather than batch processes. Unfortunately, the hydrodynamics of such flow processes is poorly understood and is difficult to assess because it requires the simultaneous measurements of liquid/solids phase velocities and volume fractions. Due to the recent development in pulsed Fourier Transform NMR imaging, NMR imaging is now becoming a powerful technique for the non intrusive investigation of multi-phase flows. This paper reports and exposes a state-of-the-art experimental and theoretical methodology that can be used to study such flows. The hydrodynamic model developed for this study is a two-phase flow shear thinning model with standard constitutive fluid/solids interphase drag and solids compaction stresses. this model shows good agreement with experimental data and the limitations of this model are discussed.

  20. 46 CFR 180.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If... to deterioration from ultraviolet light. (e) If the vessel carries more than one life float...

  1. 46 CFR 180.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If... to deterioration from ultraviolet light. (e) If the vessel carries more than one life float...

  2. 46 CFR 180.137 - Stowage of life floats and buoyant apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If... to deterioration from ultraviolet light. (e) If the vessel carries more than one life float...

  3. Numerical Study on the Turbulent Flow Structures of a Buoyant Pool Fire

    NASA Astrophysics Data System (ADS)

    Cheung, Sherman C. P.; Se, Camby M. K.; Yeoh, G. H.; Tu, Jiyuan

    2010-05-01

    In attempting to capture the non-linearity of the fire turbulent flow structures, a fully-coupled Large Eddy Simulation (LES) model which incorporates all essential subgrid scale (SGS) turbulence, combustion, radiation and soot chemistry considerations has been developed. This paper presents a thorough validation study comparing predictions of the present model with a one-meter diameter methane pool fire experimental data [1] as well as numerical results from other well-known LES models [2-3]. The predicted time-averaged velocities and turbulent quantities have been found to be in good agreement with the experimental data and other model predictions. In term of transient flow structures, for the very first time, the predicted instantaneous velocity field show satisfactory agreement with the Particle Image Velocimetry (PIV) measurements demonstrating the success of capturing the temporal vortical structure by the present model. Quantitative comparisons of velocity time history and pulsation frequency also show close agreement against experimentally evaluated quantities. Nonetheless, turbulent kinetic energy was slightly over-predicted by the present model. Possible sources of errors are discussed leading to the potential direction for future model.

  4. Near-Limit Flamelet Phenomena in Buoyant Low Stretch Diffusion Flames Beneath a Solid Fuel

    NASA Technical Reports Server (NTRS)

    Olson, S. L.; Tien, J. S.

    2000-01-01

    A unique near-limit low stretch multidimensional stable flamelet phenomena has been observed for the first time which extends the material flammability limit beyond the one-dimensional low stretch flammability limit to lower burning rates and higher relative heat losses than is possible with uniform flame coverage. During low stretch experiments burning the underside of very large radii (greater than or = 75 cm stretch rate less than or = 3/s) cylindrical cast PMMA samples, multidimensional flamelets were observed, in contrast with a one-dimensional flame that was found to blanket the surface for smaller radii samples ( higher stretch rate). Flamelets were observed by decreasing the stretch rate or by increasing the conductive heat loss from the flame. Flamelets are defined as flames that cover only part of the burning sample at any given time, but persist for many minutes. Flamelet phenomena is viewed as the flame's method of enhancing oxygen flow to the flame, through oxygen transport into the edges of the flamelet. Flamelets form as heat losses (surface radiation and solid-phase conduction) become large relative to the weakened heat release of the low stretch flame. While heat loss rates remain fairly constant, the limiting factor in the heat release of the flame is hypothesized to be the oxygen transport to the flame in this low stretch (low convective) environment. Flamelet extinction is frequently caused by encroachment of an adjacent flamelet. Large-scale whole-body flamelet oscillations at 1.2 - 1.95 Hz are noted prior to extinction of a flamelet. This oscillation is believed to be due a repeated process of excess fuel leakage through the dark channels between the flamelets, fuel premixing with slow incoming oxidizer, and subsequent rapid flame spread and retreat of the flamelet through the premixed layer. The oscillation frequency is driven by gas-phase diffusive time scales.

  5. Displacement forces on a neutral current detector from a buoyant and flexible cable under tension

    SciTech Connect

    Walston, S.

    1994-05-01

    As a means for maintaining order in the 112 NCD readout cables, it is proposed to put the cables under tension in such a way that they lie as straight as possible and rest along the top surface of the acrylic D{sub 2}O vessel. However, one aim is to avoid using top anchor points to secure the NCDs in the D{sub 2}O vessel, but rather to just let the counter`s inherent buoyancy maintain the necessary vertical orientation. As a result, applying a tension to the readout cable may pull the counters too far off of vertical. Whether or not the counter is pulled too far off of vertical depends in large part on the characteristics of the cable, i.e. modulus of elasticity and initial radius of curvature. Given that the applied tension in equilibrium is just equal to the restoring force on the counter when pulled off of vertical by some arbitrarily small amount, and given that the final radius of curvature of the readout cable is 6 meters (the radius of the D{sub 2}O vessel), what then must the modulus of elasticity be for a given initial radius of curvature of the cable? This assumes that the cable will be wrapped around a spool or somehow coiled for shipment. This also assumes that upon delivery of the cables, some effort can be made to straighten them out somewhat. For this approximation, the buoyancy of the cables is assumed to be negligible. The small length of cable that does not rest against the inner surface of the D{sub 2}O vessel is also neglected.

  6. Buoyant production and consumption of turbulence kinetic energy in cloud-topped mixed layers

    NASA Technical Reports Server (NTRS)

    Randall, D. A.

    1984-01-01

    It is pointed out that studies of the entraining planetary boundary layer (PBL) have generally emphasized the role of buoyancy fluxes in driving entrainment. The buoyancy flux is proportional to the rate of conversion of the potential energy of the mean flow into the kinetic energy of the turbulence. It is not unusual for conversion to proceed in both directions simultaneously. This occurs, for instance, in both clear and cloudy convective mixed layers which are capped by inversions. A partitioning of the net conversion into positive parts, generating turbulence kinetic energy (TKE), and negative parts (TKE-consuming), would make it possible to include the positive part in the gross production rate, and closure would be achieved. Three different approaches to partitioning have been proposed. The present investigation is concerned with a comparison of the three partitioning theories. Particular attention is given to the cloud-topped mixed layer because in this case the differences between two partitioning approaches are most apparent.

  7. The effect of wind mixing on the vertical distribution of buoyant plastic debris

    NASA Astrophysics Data System (ADS)

    Kukulka, T.; Proskurowski, G.; Morét-Ferguson, S.; Meyer, D. W.; Law, K. L.

    2012-04-01

    Micro-plastic marine debris is widely distributed in vast regions of the subtropical gyres and has emerged as a major open ocean pollutant. The fate and transport of plastic marine debris is governed by poorly understood geophysical processes, such as ocean mixing within the surface boundary layer. Based on profile observations and a one-dimensional column model, we demonstrate that plastic debris is vertically distributed within the upper water column due to wind-driven mixing. These results suggest that total oceanic plastics concentrations are significantly underestimated by traditional surface measurements, requiring a reinterpretation of existing plastic marine debris data sets. A geophysical approach must be taken in order to properly quantify and manage this form of marine pollution.

  8. Biofouling on buoyant marine plastics: An experimental study into the effect of size on surface longevity.

    PubMed

    Fazey, Francesca M C; Ryan, Peter G

    2016-03-01

    Recent estimates suggest that roughly 100 times more plastic litter enters the sea than is found floating at the sea surface, despite the buoyancy and durability of many plastic polymers. Biofouling by marine biota is one possible mechanism responsible for this discrepancy. Microplastics (<5 mm in diameter) are more scarce than larger size classes, which makes sense because fouling is a function of surface area whereas buoyancy is a function of volume; the smaller an object, the greater its relative surface area. We tested whether plastic items with high surface area to volume ratios sank more rapidly by submerging 15 different sizes of polyethylene samples in False Bay, South Africa, for 12 weeks to determine the time required for samples to sink. All samples became sufficiently fouled to sink within the study period, but small samples lost buoyancy much faster than larger ones. There was a direct relationship between sample volume (buoyancy) and the time to attain a 50% probability of sinking, which ranged from 17 to 66 days of exposure. Our results provide the first estimates of the longevity of different sizes of plastic debris at the ocean surface. Further research is required to determine how fouling rates differ on free floating debris in different regions and in different types of marine environments. Such estimates could be used to improve model predictions of the distribution and abundance of floating plastic debris globally.

  9. Seismic evidence for hotspot-induced buoyant flow beneath the Reykjanes Ridge.

    PubMed

    Gaherty, J B

    2001-08-31

    Volcanic hotspots and mid-ocean ridge spreading centers are the surface expressions of upwelling in Earth's mantle convection system, and their interaction provides unique information on upwelling dynamics. I investigated the influence of the Iceland hotspot on the adjacent mid-Atlantic spreading center using phase-delay times of seismic surface waves, which show anomalous polarization anisotropy-a delay-time discrepancy between waves with different polarizations. This anisotropy implies that the hotspot induces buoyancy-driven upwelling in the mantle beneath the ridge.

  10. Academically Buoyant Students Are Less Anxious about and Perform Better in High-Stakes Examinations

    ERIC Educational Resources Information Center

    Putwain, David W.; Daly, Anthony L.; Chamberlain, Suzanne; Sadreddini, Shireen

    2015-01-01

    Background: Prior research has shown that test anxiety is negatively related to academic buoyancy, but it is not known whether test anxiety is an antecedent or outcome of academic buoyancy. Furthermore, it is not known whether academic buoyancy is related to performance on high-stakes examinations. Aims: To test a model specifying reciprocal…

  11. Influence of buoyant media on particle layer dynamics in microfiltration membranes.

    PubMed

    Aryal, R K; Vigneswaran, S; Kandasamy, Jaya

    2010-01-01

    This study forms a part of the physical study of the membrane bioreactor in presence of buoyancy media. Kaolin clay suspension with buoyancy media (anthracite) was used as a suspension and the particle layer development on membrane surface with evolution of time was studied. Presence of buoyancy media reduced the pressure development by almost two folds compared to in absence of the media. The particles deposition on membrane surface was size selective. The mean particle diameter (0.45 mum) deposited on the membrane surface remained almost similar in presence of the media after 7 hrs run where as in its absence the mean diameter finer particles deposition occurred at the beginning followed by coarser particles.

  12. Buoyant low stretch stagnation point diffusion flames over a solid fuel

    NASA Astrophysics Data System (ADS)

    Olson, Sandra L.

    Many diffusion flames in microgravity are subject to very low stretch. To study flame structure and extinction characteristics of these unusual flames, a normal gravity low-stretch diffusion flame is generated using a cylindrical PMMA sample of varying large radii. Solid-phase conductive heat loss was also varied by modifying the back surface boundary conditions on the samples. Burning rates, flame thickness and standoff distance, temperature profiles in the solid and gas, and radiative loss from the system were measured. A transition from the blowoff side of the flammability map to the quenching side of the flammability map is observed at approximately 7-8 secsp{-1}, as determined by the non-monotonic trends in peak temperatures, solid and gas-phase temperature gradients, and non-dimensional standoff distances. A unique local extinction flamelet phenomena and associated pre-extinction oscillations are observed at very low stretch. An ultimate quenching extinction limit is found at low stretch with sufficiently high induced heat losses. A surface energy balance reveals that the fraction of heat transfer from the flame that is lost to in-depth conduction and surface radiation increases with decreasing stretch until quenching extinction is observed. This is primarily due to decreased heat transfer from the flame. Applications of this work include fire safety in spacecraft where low velocity flows from spacecraft ventilation equipment or small cooling fans for electronic hardware can impinge upon flammable surface materials and create low stretch environments. Knowledge of the characteristics of these potential fires is vital to prompt detection and proper response to such events.

  13. Unmanned Aircraft in the Measurement of Carbon Dioxide in Buoyant Plumes

    NASA Astrophysics Data System (ADS)

    Jacob, J.

    2015-12-01

    Carbon sequestration, the storage of carbon dioxide gas underground, has the potential to reduce global warming by removing a greenhouse gas from the atmosphere. These storage sites, however, must first be monitored to detect if carbon dioxide is leaking back out to the atmosphere. As an alternative to traditional large ground-based sensor networks to monitor CO2 levels for leaks, unmanned aircraft offer the potential to perform in-situ atmospheric leak detection over large areas for a fraction of the cost. This project developed a proof-of-concept sensor system to map relative carbon dioxide levels to detect potential leaks. Ground tests were performed to verify and calibrate the system including wind tunnel tests to determine the optimal configuration of the system to account for dynamic calibration models required to determine accurate location of gas concentration in (x,y,z,t). Field tests were then conducted over a controlled release of CO2 as well as over controlled rangeland fires which released carbon dioxide over a large area. 3D maps of carbon dioxide were developed from the system telemetry that clearly illustrated increased CO2 levels from the fires. Results are compared with dynamic atmospheric models of gas dispersion within plumes.

  14. Increased methane emissions from deep osmotic and buoyant convection beneath submarine seeps as climate warms

    PubMed Central

    Cardoso, Silvana S. S.; Cartwright, Julyan H. E.

    2016-01-01

    High speeds have been measured at seep and mud-volcano sites expelling methane-rich fluids from the seabed. Thermal or solute-driven convection alone cannot explain such high velocities in low-permeability sediments. Here we demonstrate that in addition to buoyancy, osmotic effects generated by the adsorption of methane onto the sediments can create large overpressures, capable of recirculating seawater from the seafloor to depth in the sediment layer, then expelling it upwards at rates of up to a few hundreds of metres per year. In the presence of global warming, such deep recirculation of seawater can accelerate the melting of methane hydrates at depth from timescales of millennia to just decades, and can drastically increase the rate of release of methane into the hydrosphere and perhaps the atmosphere. PMID:27807343

  15. A buoyant tornado-probe concept incorporating an inverted lifting device. [and balloon combination

    NASA Technical Reports Server (NTRS)

    Grant, F. C.

    1973-01-01

    Addition of an inverted lifting device to a simple balloon probe is shown to make possible low-altitude entry to tornado cores with easier launch conditions than for the simple balloon probe. Balloon-lifter combinations are particularly suitable for penetration of tornadoes with average to strong circulation, but tornadoes of less than average circulation which are inaccessible to simple balloon probes become accessible. The increased launch radius which is needed for access to tornadoes over a wide range of circulation results in entry times of about 3 minutes. For a simple balloon probe the uninflated balloon must be first dropped on, or near, the track of the tornado from a safe distance. The increase in typical launch radius from about 0.75 kilometer to slightly over 1.0 kilometer with a balloon-lifter combination suggests that a direct air launch may be feasible.

  16. Model-Based Inquiry: A Buoyant Force Module for High School Physics Classes

    ERIC Educational Resources Information Center

    Neilson, Drew; Campbell, Todd; Allred, Benjamin

    2010-01-01

    Model-Based Inquiry (MBI) is an emergent instructional strategy that is gaining acceptance among science educators. This approach to learning realistically mirrors the work of scientists, who develop and test hypotheses to construct more sophisticated understandings of the natural world. This article details how the authors collaboratively taught…

  17. Effect of large density ratios on turbulence budgets in buoyant jets with coflow

    NASA Astrophysics Data System (ADS)

    Charonko, John; Prestridge, Kathy

    2016-11-01

    Turbulence statistics and energy transport budgets have been measured in two fully turbulent jets with coflow at density ratios of s = 1 . 2 & 4.2 to improve our understanding of variable-density mixing in turbulent flows. The exit Reynolds number was matched for both flows at 20,000 and simultaneous planar PIV and acetone PLIF measurements were acquired so the coupled evolution of the velocity and density statistics could be examined in terms of density-weighted average quantities. Measurements were taken over 10,000 snapshots of the flow at three locations to assure statistical convergence, and the spatial resolution (288 μm) is well below the Taylor microscale. Variable-density effects caused changes in both the magnitude and distribution of the evolving turbulence, with differences most pronounced within the jet half-width. As the jet tends toward pseudo self-similarity, a new scaling based on effective diameter and density successfully scales the energy budgets of the two jets, but significant differences were still seen in the core. For the high density ratio jet, the turbulent kinetic energy production is negative on the centerline, as opposed to slightly positive, leading to large changes in advection and diffusion. A mechanism for these differences is proposed.

  18. Modelling fluctuations in the concentration of neutrally buoyant substances in the atmosphere

    NASA Astrophysics Data System (ADS)

    Ride, David John

    1987-12-01

    The probability density function (PDF) of the perceived concentration of a contaminant in the atmosphere is modeled using simple, physical representations of the dispersing contaminant. Sensors are characterized by the time taken to achieve a reading and by a threshold level of concentration below which the sensor does not respond and thus records a concentration of zero. A literature search of theoretical and experimental work concerning concentration fluctuations is conducted, and the merits - or otherwise - of of some common PDF's in common use are discussed.

  19. Modelling Fluctuations in the Concentration of Neutrally Buoyant Substances in the Atmosphere.

    NASA Astrophysics Data System (ADS)

    Ride, David John

    1987-09-01

    Available from UMI in association with The British Library. This thesis sets out to model the probability density function (pdf) of the perceived concentration of a contaminant in the atmosphere using simple, physical representations of the dispersing contaminant. Sensors of differing types perceive a given concentration field in different ways; the chosen pdf must be able to describe all possible perceptions of the same field. Herein, sensors are characterised by the time taken to achieve a reading and by a threshold level of concentration below which the sensor does not respond and thus records a concentration of zero. A literature survey of theoretical and experimental work concerning concentration fluctuations is conducted, and the merits--or otherwise--of some standard pdfs in common use are discussed. The ways in which the central moments, the peak-to-mean ratio, the intermittency and the autocorrelation function behave under various combinations of threshold levels and time averaging are investigated. An original experiment designed to test the suitability of time averaging as a valid simulation of both sensor response times and sampling volumes is reported. The results suggest that, for practical purposes, smoothing from combined volume/time characteristics of a sensor can be modelled by time averaging the output of a more responsive sensor. A possible non -linear volume/time effect was observed at very high temporal resolutions. Intermittency is shown to be an important parameter of the concentration field. A geometric model for describing and explaining the intermittency of a meandering plume of material in terms of the ratio of the plume width to the amplitude of meander and the within-plume intermittency is developed and validated. It shows that the model cross plume profiles of intermittency cannot, in general, be represented by simple functional forms. A new physical model for the fluctuations in concentration from a dispersing contaminant is described which leads to the adoption of a truncated Gaussian (or 'clipped normal') pdf for time averaged concentrations. A series of experiments is described which was designed to test the aptness of this distribution and display changes in the perception of the parameters of the concentration field wrought by various combinations of thresholding and time averaging. The truncated Gaussian pdf is shown to be more suitable for describing fluctuations than the log-normal and negative exponential pdfs, and to possess a better physical basis than either of them. The combination of thresholding and time averaging on the output of a sensor is shown to produce complex results which could affect profoundly the assessment of the potential hazard presented by a toxic, flammable or explosive plume or cloud.

  20. Molecular genetic and physical analysis of gas vesicles in buoyant enterobacteria

    PubMed Central

    Tashiro, Yosuke; Monson, Rita E.; Ramsay, Joshua P.

    2016-01-01

    Summary Different modes of bacterial taxis play important roles in environmental adaptation, survival, colonization and dissemination of disease. One mode of taxis is flotation due to the production of gas vesicles. Gas vesicles are proteinaceous intracellular organelles, permeable only to gas, that enable flotation in aquatic niches. Gene clusters for gas vesicle biosynthesis are partially conserved in various archaea, cyanobacteria, and some proteobacteria, such as the enterobacterium, S erratia sp. ATCC 39006 (S39006). Here we present the first systematic analysis of the genes required to produce gas vesicles in S39006, identifying how this differs from the archaeon H alobacterium salinarum. We define 11 proteins essential for gas vesicle production. Mutation of gvpN or gvpV produced small bicone gas vesicles, suggesting that the cognate proteins are involved in the morphogenetic assembly pathway from bicones to mature cylindrical forms. Using volumetric compression, gas vesicles were shown to comprise 17% of S39006 cells, whereas in E scherichia coli heterologously expressing the gas vesicle cluster in a deregulated environment, gas vesicles can occupy around half of cellular volume. Gas vesicle production in S39006 and E . coli was exploited to calculate the instantaneous turgor pressure within cultured bacterial cells; the first time this has been performed in either strain. PMID:26743231

  1. The behaviour of buoyant plumes in neutral and stable conditions in canada

    NASA Astrophysics Data System (ADS)

    Whaley, H.; Lee, G. K.

    Plume dispersion parameters obtained during six years of research by the Canadian Combustion Research Laboratory (CCRL) have been evaluated and compared to the standard predictive relationships established by Briggs and Pasquill-Gifford. The data correspond to neutral and stable conditions, stability class C to F but excludes any limited-mixing or layered atmosphere studies or situations where topography influences plume spread. In all, ten sources in five geographic regions were studied during Spring, Fall and Winter. It has been shown that the plume rise data can be represented by the Briggs and Moore form of relationship for neutral conditions. The data suggest a proportionality constant of 0.87 and a levelling-off at 15 stack heights when constrained to the 2/3 power law required by the Briggs continuous model. The unconstrained regression yielded a constant of 0.5 and 0.71 power law relationship with downwind distance, between the Briggs and Moore relationships. However, both of the latter significantly overestimate the measured data. In stable conditions the Briggs levelling-off value of 2.9 for the dimensionless plume rise is in good agreement with the findings in this paper, but this occurs at a dimensionless downwind distance of 18.4 rather than 2.4. A slight variation in the maximum plume rise with the bulk Richardson number over the dispersion zone has been noted for stable conditions. The Pasquill-Gifford plume spread curves as modified by Bowne for rural conditions represent a convenient means of comparing the data obtained under corresponding stability and topographic conditions in Canada. The variation of measured horizontal spread parameters, σy with downwind distance differed significantly from the P/G curves, being wider by at least two stability classes for unstable/neutral, i.e. A/B rather than C/D, and for stable, C rather than E. In the case of very stable F class, the measured σy values corresponded to A class, six classes wider than expected. The vertical spread parameters, σz were usually in agreement with P/G curves from 4 to 10 km from the source, closer to the source σz was greater and farther from the source σz was less than predicted. It was also found that the bulk Richardson number could be used to classify the plume spread parameters in a similar manner to the P/G stability classes.

  2. The wind-forced response on a buoyant coastal current: Observations of the western Gulf of Maine plume

    USGS Publications Warehouse

    Fong, D.A.; Geyer, W.R.; Signell, R.P.

    1997-01-01

    The Freshwater plume in the western Gulf of Maine is being studied as part of an interdisciplinary investigation of the physical transport of a toxic alga. A field program was conducted in the springs of 1993 and 1994 to map the spatial and temporal patterns of salinity, currents and algal toxicity. The observations suggest that the plume's cross-shore structure varies markedly as a function of fluctuations in alongshore wind forcing. Consistent with Ekman drift dynamics, upwelling favorable winds spread the plume offshore, at times widening it to over 50 km in offshore extent, while downwelling favorable winds narrow the plume width to as little as 10 km. Using a simple slab model, we find qualitative agreement between the observed variations of plume width and those predicted by Ekman theory for short time scales of integration. Near surface current meters show significant correlations between cross-shore currents and alongshore wind stress, consistent with Ekman theory. Estimates of the terms in the alongshore momentum equation calculated from moored current meter arrays also indicate a dominant Ekman balance within the plume. A significant correlation between alongshore currents and winds suggests that interfacial drag may be important, although inclusion of a Raleigh drag term does not significantly improve the alongshore momentum balance.

  3. Alginate gel-coated oil-entrapped alginate-tamarind gum-magnesium stearate buoyant beads of risperidone.

    PubMed

    Bera, Hriday; Boddupalli, Shashank; Nandikonda, Sridhar; Kumar, Sanoj; Nayak, Amit Kumar

    2015-01-01

    A novel alginate gel-coated oil-entrapped calcium-alginate-tamarind gum (TG)-magnesium stearate (MS) composite floating beads was developed for intragastric risperidone delivery with a view to improving its oral bioavailability. The TG-blended alginate core beads containing olive oil and MS as low-density materials were accomplished by ionotropic gelation technique. Effects of polymer-blend ratio (sodium alginate:TG) and crosslinker (CaCl2) concentration on drug entrapment efficiency (DEE, %) and cumulative drug release after 8 h (Q8h, %) were studied to optimize the core beads by a 3(2) factorial design. The optimized beads (F-O) exhibited DEE of 75.19±0.75% and Q8h of 78.04±0.38% with minimum errors in prediction. The alginate gel-coated optimized beads displayed superior buoyancy and sustained drug release property. The drug release profiles of the drug-loaded uncoated and coated beads were best fitted in Higuchi kinetic model with Fickian and anomalous diffusion driven mechanisms, respectively. The optimized beads yielded a notable sustained drug release profile as compared to marketed immediate release preparation. The uncoated and coated Ca-alginate-TG-MS beads were also characterized by SEM, FTIR and P-XRD analyses. Thus, the newly developed alginate-gel coated oil-entrapped alginate-TG-MS composite beads are suitable for intragastric delivery of risperidone over a prolonged period of time.

  4. The effect of neutrally buoyant finite-size particles on channel flows in the laminar-turbulent transition regime

    NASA Astrophysics Data System (ADS)

    Loisel, Vincent; Abbas, Micheline; Masbernat, Olivier; Climent, Eric

    2013-12-01

    The presence of finite-size particles in a channel flow close to the laminar-turbulent transition is simulated with the Force Coupling Method which allows two-way coupling with the flow dynamics. Spherical particles with channel height-to-particle diameter ratio of 16 are initially randomly seeded in a fluctuating flow above the critical Reynolds number corresponding to single phase flow relaminarization. When steady-state is reached, the particle volume fraction is homogeneously distributed in the channel cross-section (ϕ ≅ 5%) except in the near-wall region where it is larger due to inertia-driven migration. Turbulence statistics (intensity of velocity fluctuations, small-scale vortical structures, wall shear stress) calculated in the fully coupled two-phase flow simulations are compared to single-phase flow data in the transition regime. It is observed that particles increase the transverse r.m.s. flow velocity fluctuations and they break down the flow coherent structures into smaller, more numerous and sustained eddies, preventing the flow to relaminarize at the single-phase critical Reynolds number. When the Reynolds number is further decreased and the suspension flow becomes laminar, the wall friction coefficient recovers the evolution of the laminar single-phase law provided that the suspension viscosity is used in the Reynolds number definition. The residual velocity fluctuations in the suspension correspond to a regime of particulate shear-induced agitation.

  5. Deformation and orientation statistics of neutrally buoyant sub-Kolmogorov ellipsoidal droplets in turbulent Taylor-Couette flow

    NASA Astrophysics Data System (ADS)

    Spandan, Vamsi; Lohse, Detlef; Verzicco, Roberto

    2016-12-01

    The influence of the underlying flow topology on the shape and size of sub-Kolmogorov droplets dispersed in a turbulent flow is of considerable interest in many industrial and scientific applications. In this work we study the deformation and orientation statistics of sub-Kolmogorov droplets dispersed into a turbulent Taylor-Couette flow. Along with Direct Numerical Simulations (DNS) of the carrier phase and Lagrangian tracking of the dispersed droplets, we solve a phenomenological equation proposed by Maffettone and Minale (\\emph{J. Fluid Mech.} 78, 227-241 (1998)) to track the shape evolution and orientation of approximately $10^5$ ellipsoidal droplets. By varying the capillary number $Ca$ and viscosity ratio $\\hat \\mu$ of the droplets we find that the droplets deform more with increasing capillary number $Ca$ and this effect is more pronounced in the boundary layer regions. This indicates that along with a capillary number effect there is also a strong correlation between spatial position and degree of deformation of the droplet. Regardless of the capillary number $Ca$, the major-axis of the ellipsoids tends to align with the stream-wise direction and the extensional strain rate eigen direction in the boundary layer region while the distribution is highly isotropic in the bulk. When the viscosity ratio between the droplet and the carrier fluid is increased we find that there is no preferential stretched axis which is due to the increased influence of rotation over stretching and relaxation. Droplets in high viscosity ratio systems are thus less deformed and oblate (disk-like) as compared to highly deformed prolate (cigar-like) droplets in low viscosity ratio systems.

  6. Determination of buoyant density and sensitivity to chloroform and freon for the etiological agent of infectious salmonid anaemia

    USGS Publications Warehouse

    Christie, K.E.; Hjeltnes, B.; Uglenes , I.; Winton, J.R.

    1993-01-01

    Plasma was collected from Atlantic salmon Salrno salar with acute infectious salmon anaemia (ISA) and used to challenge Atlantic salmon parr by intraperitoneal injection. Treatment of plasma with the lipid solvent, chloroform, showed that the etiological agent of ISA contained essential lipids, probably as a viral envelope. Some infectivity remained following treatment with freon. Injection challenges using fractions from equilibrium density gradient centrifugation of plasma from fish with acute ISA revealed a band of infectivity in the range 1.184 to 1.262 g cm-3. The band was believed to conta~n both complete ISA-virus particles and infectious particles lacking a complete envelope, nucleocapsid or genome. Density gradient centrifugation of infectious plasma for enrichment of the putative ISA virus appeared to offer a suitable method for obtaining virus-specific nucleic acid for use in the construction of cDNA libraries. 

  7. Ranitidine Hydrochloride-loaded Ethyl Cellulose and Eudragit RS 100 Buoyant Microspheres: Effect of pH Modifiers

    PubMed Central

    Kotagale, N. R.; Parkhe, A. P.; Jumde, A. B.; Khandelwal, H. M.; Umekar, M. J.

    2011-01-01

    A floating type of dosage form of ranitidine hydrochloride in the form of microspheres capable of floating on simulated gastric fluid was prepared by solvent evaporation technique. Microspheres prepared with ethyl cellulose, Eudragit® RS100 alone or in combination were evaluated for percent yield, drug entrapment, percent buoyancy and drug release and the results demonstrated satisfactory performance. Microspheres exhibited ranitidine hydrochloride release influenced by changing ranitidine hydrochloride-polymer and ranitidine hydrochloride-polymer-polymer ratio. Incorporation of a pH modifier has been the usual strategy employed to enhance the dissolution rate of weakly basic drug from floating microspheres. Further citric acid, fumaric acid, tartaric acid were employed as pH modifiers. Microspheres prepared with ethyl cellulose, Eudragit® RS100 and their combination that showed highest release were utilized to study the effect of pH modifiers on ranitidine hydrochloride release from microspheres which is mainly affected due to modulation of microenvironmental pH. In vitro release of ranitidine hydrochloride from microspheres into simulated gastric fluid at 37° showed no significant burst effect. However the amount of release increased with time and significantly enhanced by pH modifiers. 15% w/w concentration of fumaric acid provide significant drug release from ranitidine hydrochloride microspheres prepared with ranitidine hydrochloride:ethyl cellulose (1:3), ranitidine hydrochloride:Eudragit® RS100 (1:2) and ranitidine hydrochloride:ethyl cellulose:Eudragit® RS100 (1:2:1) whereas citric acid, tartaric acid showed significant cumulative release at 20% w/w. In all this study suggest that ethyl celluose, Eudragit® RS100 alone or in combination with added pH modifiers can be useful in floating microspheres which can be proved beneficial to enhance the bioavailability of ranitidine hydrochloride. PMID:23112396

  8. Buoyant thermocapillary flow with nonuniform supra-heating. I - Liquid-phase behavior. II - Two-phase behavior

    NASA Technical Reports Server (NTRS)

    Schiller, David N.; Sirignano, William A.

    1992-01-01

    The present computational study of transient heat transfer and fluid flow in a circular pool of n-decane which is undergoing central radiative heating from above gives attention to the volumetric absorption of the radiation incident on the pool surface. The first part of this study notes that buoyancy influences the number and recirculation rates of the subsurface vortices by stabilizing hot subsurface fluid above the colder core fluid; this affects the liquid surface temperature profile and in turn governs the velocity profile that is due to thermocapillarity. In the second part, the effects of gas-liquid phase coupling, variable density and thermophysical properties, and vaporization are considered.

  9. Thermal transport due to buoyant flow past a vertical, heated superhydrophobic surface with uniform stream-wise slip

    NASA Astrophysics Data System (ADS)

    Searle, Matthew; Maynes, Daniel; Crockett, Julie

    2016-11-01

    An analytical investigation of thermal transport due to a steady, laminar, buoyancy-driven flow past a vertical superhydrophobic (SHPo) surface was performed. The surface temperature was constant and uniform and exceeded the temperature of the surrounding liquid. Uniform stream-wise hydrodynamic slip and temperature jump are imposed at the wall to model the SHPo surface. Applying an integral analysis within the boundary layer results in a system of differential equations which are solved numerically to obtain boundary layer thickness, maximum velocity in the profile, and local and average values of both the friction coefficient and the Nusselt number. The classical smooth hydrophobic scenario with no-slip and no temperature jump showed excellent agreement with previous analysis of the same problem. The influence of varying temperature jump length on the local and average values of the friction coefficient and the Nusselt number was obtained for Rayleigh number ranging from 104 to 109 and Prandtl number ranging from 2 to 11. Local and average Nusselt numbers decrease dramatically, concomitant with a decrease in the maximum fluid velocity, as the temperature jump length increases. National Science Foundation(NSF) Grant No. CBET-1235881.

  10. A new Quantitative Interpretation of Explosive Eruption Deposits Based on a Physical Model of Negatively Buoyant Jets

    NASA Astrophysics Data System (ADS)

    Carazzo, G.; Kaminski, E.; Tait, S.

    2006-12-01

    High-velocity turbulent jets from explosive volcanic eruptions belong to the most powerful and dangerous flows on Earth. Their fluid dynamics has come to be characterized in terms of two end-member behaviors: in the first, the jet rises high into the atmosphere by natural convection (the "plinian" regime), in the second, it collapses to form pyroclastic flows around the vent. These unusual dynamics were initially deduced from the structure of deposits and have now also been confirmed by observations of historical eruptions. A major goal of physical volcanology has been to predict quantitatively which of the two basic flow regimes will occur, thus delineating the transition between them, as a function of exit conditions (most importantly mass flux) specified at the vent. A thorough review of the available data shows however that model predictions of the transition are in error by more than one order of magnitude in terms of mass flux. There has been no common agreement on whether this is most likely due to poor knowledge of geologic parameters or to inadequacies in the physical description of the dynamics. Here, we focus on the second point and in particular on the rate of entrainment into the jet. We demonstrate that the "entrainment coefficient" governing turbulent mixing is not a constant, as has been commonly assumed, but is greatly reduced near the base of the jet due to negative buoyancy. We show that the results of our new quantitative model, allowing for variable entrainment as a function of local Richardson number, are in excellent agreement with field data from a large number of eruptions.

  11. Laminar round jet diffusion flame buoyant instabilities: Study on the disappearance of varicose structures at ultra-low Froude number

    SciTech Connect

    Boulanger, Joan

    2010-04-15

    At very low Froude number, buoyancy instabilities of round laminar jet diffusion flames disappear (except for small tip oscillations referred to as flickering) and those flames look stable and smooth. This study examines the contributions of the different phenomena in the flow dynamics that may explain this effect. It is observed that, at ultra-low Froude/Reynolds numbers, the material influenced by buoyancy is the plume of the flame and not the flame itself (reaction zone) that is short. Therefore, the vorticity creation zone does not profit from the reaction neighbourhood promoting a sharp gradient of density. Expansion and stretch are also important as they push vorticity creation terms more inside the flame and closer to the burner rim compared to moderate Froude flames. In these latter, the vorticity is continuously created around the flame reaction zone, along its developed height and closer to the vertical direction (in average). (author)

  12. 46 CFR 160.060-8 - Marking.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant...

  13. 46 CFR 160.060-8 - Marking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant...

  14. 46 CFR 160.060-8 - Marking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant...

  15. 46 CFR 160.060-8 - Marking.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant...

  16. 46 CFR 160.060-8 - Marking.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant...

  17. 46 CFR 160.047-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  18. 46 CFR 160.052-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  19. 46 CFR 160.052-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  20. 46 CFR 160.047-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  1. 46 CFR 160.052-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  2. 46 CFR 160.047-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  3. 46 CFR 160.052-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  4. 46 CFR 160.047-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  5. 46 CFR 160.047-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  6. 46 CFR 160.052-3a - Materials-Dee ring and snap hook assemblies and other instruments of closure for buoyant vests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... tested for weathering. The Coast Guard will determine which one or more of the following tests will be... minutes of completion of the weathering test required by paragraph (b)(1) of this section, the...

  7. Potential migration of buoyant LNAPL from intermediate level waste (ILW) emplaced in a geological disposal facility (GDF) for U.K. radioactive waste.

    PubMed

    Benbow, Steven J; Rivett, Michael O; Chittenden, Neil; Herbert, Alan W; Watson, Sarah; Williams, Steve J; Norris, Simon

    2014-10-15

    A safety case for the disposal of Intermediate Level (radioactive) Waste (ILW) in a deep geological disposal facility (GDF) requires consideration of the potential for waste-derived light non-aqueous phase liquid (LNAPL) to migrate under positive buoyancy from disposed waste packages. Were entrainment of waste-derived radionuclides in LNAPL to occur, such migration could result in a shorter overall travel time to environmental or human receptors than radionuclide migration solely associated with the movement of groundwater. This paper provides a contribution to the assessment of this issue through multiphase-flow numerical modelling underpinned by a review of the UK's ILW inventory and literature to define the nature of the associated ILW LNAPL source term. Examination has been at the waste package-local GDF environment scale to determine whether proposed disposal of ILW would lead to significant likelihood of LNAPL migration, both from waste packages and from a GDF vault into the local host rock. Our review and numerical modelling support the proposition that the release of a discrete free phase LNAPL from ILW would not present a significant challenge to the safety case even with conservative approximations. 'As-disposed' LNAPL emplaced with the waste is not expected to pose a significant issue. 'Secondary LNAPL' generated in situ within the disposed ILW, arising from the decomposition of plastics, in particular PVC (polyvinyl chloride), could form the predominant LNAPL source term. Released high molecular weight phthalate plasticizers are judged to be the primary LNAPL potentially generated. These are expected to have low buoyancy-based mobility due to their very low density contrast with water and high viscosity. Due to the inherent uncertainties, significant conservatisms were adopted within the numerical modelling approach, including: the simulation of a deliberately high organic material--PVC content wastestream (2D03) within an annular grouted waste package vulnerable to LNAPL release; upper bound inventory estimates of LNAPLs; incorporating the lack of any hydraulic resistance of the package vent; the lack of any degradation of dissolved LNAPL; and, significantly, the small threshold displacement pressure assumed at which LNAPL is able to enter initially water-saturated pores. Initial scoping calculations on the latter suggested that the rate at which LNAPL is able to migrate from a waste package is likely to be very small and insignificant for likely representative displacement pressure data: this represents a key result. Adopting a conservative displacement pressure, however, allowed the effect of other features and processes in the system to be assessed. High LNAPL viscosity together with low density contrast with water reduces LNAPL migration potential. Migration to the host rock is less likely if waste package vent fluxes are small, solubility limits are high and path lengths through the backfill are short. The capacity of the system to dissolve all of the free LNAPL will, however, depend on groundwater availability. Even with the conservatisms invoked, the overall conclusion of model simulations of intact and compromised (cracked or corroded) waste packages, for a range of realistic ILW LNAPL scenarios, is that it is unlikely that significant LNAPL would be able to migrate from the waste packages and even more unlikely it would be sufficiently persistent to reach the host rock immediately beyond the GDF.

  8. Potential migration of buoyant LNAPL from Intermediate Level Waste (ILW) emplaced in a geological disposal facility (GDF) for UK radioactive waste

    NASA Astrophysics Data System (ADS)

    Benbow, Steven J.; Rivett, Michael O.; Chittenden, Neil; Herbert, Alan W.; Watson, Sarah; Williams, Steve J.; Norris, Simon

    2014-10-01

    A safety case for the disposal of Intermediate Level (radioactive) Waste (ILW) in a deep geological disposal facility (GDF) requires consideration of the potential for waste-derived light non-aqueous phase liquid (LNAPL) to migrate under positive buoyancy from disposed waste packages. Were entrainment of waste-derived radionuclides in LNAPL to occur, such migration could result in a shorter overall travel time to environmental or human receptors than radionuclide migration solely associated with the movement of groundwater. This paper provides a contribution to the assessment of this issue through multiphase-flow numerical modelling underpinned by a review of the UK's ILW inventory and literature to define the nature of the associated ILW LNAPL source term. Examination has been at the waste package-local GDF environment scale to determine whether proposed disposal of ILW would lead to significant likelihood of LNAPL migration, both from waste packages and from a GDF vault into the local host rock. Our review and numerical modelling support the proposition that the release of a discrete free phase LNAPL from ILW would not present a significant challenge to the safety case even with conservative approximations. 'As-disposed' LNAPL emplaced with the waste is not expected to pose a significant issue. 'Secondary LNAPL' generated in situ within the disposed ILW, arising from the decomposition of plastics, in particular PVC (polyvinyl chloride), could form the predominant LNAPL source term. Released high molecular weight phthalate plasticizers are judged to be the primary LNAPL potentially generated. These are expected to have low buoyancy-based mobility due to their very low density contrast with water and high viscosity. Due to the inherent uncertainties, significant conservatisms were adopted within the numerical modelling approach, including: the simulation of a deliberately high organic material - PVC content wastestream (2D03) within an annular grouted waste package vulnerable to LNAPL release; upper bound inventory estimates of LNAPLs; incorporating the lack of any hydraulic resistance of the package vent; the lack of any degradation of dissolved LNAPL; and, significantly, the small threshold displacement pressure assumed at which LNAPL is able to enter initially water-saturated pores. Initial scoping calculations on the latter suggested that the rate at which LNAPL is able to migrate from a waste package is likely to be very small and insignificant for likely representative displacement pressure data: this represents a key result. Adopting a conservative displacement pressure, however, allowed the effect of other features and processes in the system to be assessed. High LNAPL viscosity together with low density contrast with water reduces LNAPL migration potential. Migration to the host rock is less likely if waste package vent fluxes are small, solubility limits are high and path lengths through the backfill are short. The capacity of the system to dissolve all of the free LNAPL will, however, depend on groundwater availability. Even with the conservatisms invoked, the overall conclusion of model simulations of intact and compromised (cracked or corroded) waste packages, for a range of realistic ILW LNAPL scenarios, is that it is unlikely that significant LNAPL would be able to migrate from the waste packages and even more unlikely it would be sufficiently persistent to reach the host rock immediately beyond the GDF.

  9. IgG Responses to Tissue-Associated Antigens as Biomarkers of Immunological Treatment Efficacy

    DTIC Science & Technology

    2011-01-01

    sipuleucel - T , Provenge, Dendreon) for patients with advanced metastatic prostate cancer. Many other agents have demonstrated benefit in large clinical trials...and approval is anticipated in the case of a monoclonal antibody targeting a T -cell checkpoint inhibitor targeting CTLA-4 (ipilimumab, Bristol-Myers...response has been associated with clinical benefit. The situation is more difficult for broadly active immune modulating agents such as T -cell checkpoint

  10. 46 CFR 160.052-5 - Construction-standard vests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam...) Buoyant inserts. The unicellular plastic foam buoyant inserts shall be cut and formed as shown on Dwg....

  11. 46 CFR 160.052-5 - Construction-standard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam...) Buoyant inserts. The unicellular plastic foam buoyant inserts shall be cut and formed as shown on Dwg....

  12. 46 CFR 160.052-5 - Construction-standard vests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam...) Buoyant inserts. The unicellular plastic foam buoyant inserts shall be cut and formed as shown on Dwg....

  13. 46 CFR 160.052-5 - Construction-standard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam...) Buoyant inserts. The unicellular plastic foam buoyant inserts shall be cut and formed as shown on Dwg....

  14. 46 CFR 160.010-2 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Buoyant Apparatus for Merchant Vessels § 160.010-2 Definitions. Buoyant apparatus. Buoyant apparatus is flotation equipment (other than lifeboats, liferafts, and...

  15. 46 CFR 160.060-1 - Incorporation by reference.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b) Plans. The following plans, of the issue in...

  16. 46 CFR 160.060-1 - Incorporation by reference.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b) Plans. The following plans, of the issue in...

  17. 46 CFR 160.060-1 - Incorporation by reference.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b) Plans. The following plans, of the issue in...

  18. 46 CFR 160.060-1 - Incorporation by reference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b) Plans. The following plans, of the issue in...

  19. 46 CFR 160.060-1 - Incorporation by reference.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b) Plans. The following plans, of the issue in...

  20. 46 CFR 160.049-4 - Construction and workmanship.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam... box type filled with unicellular plastic foam buoyant material. Such cushions consist essentially of...

  1. 46 CFR 160.049-4 - Construction and workmanship.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam... box type filled with unicellular plastic foam buoyant material. Such cushions consist essentially of...

  2. 46 CFR 160.052-1 - Incorporation by reference.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam..., Unicellular Plastic Foam, Adult and Child. 164.015—Plastic Foam, Unicellular, Buoyant Sheet and Molded...

  3. 46 CFR 160.052-1 - Incorporation by reference.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam..., Unicellular Plastic Foam, Adult and Child. 164.015—Plastic Foam, Unicellular, Buoyant Sheet and Molded...

  4. 46 CFR 160.049-7 - Procedure for approval.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam § 160.049-7... be granted separately to each manufacturer for each unicellular plastic foam buoyant cushion...

  5. 46 CFR 160.047-1 - Incorporation by reference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Kapok or Fibrous Glass, Adult...) Plans. The following plans, of the issue in effect on the date buoyant vests are manufactured, form...

  6. 46 CFR 160.052-1 - Incorporation by reference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam.... (b) Plans. The following plans, of the issue in effect on the date buoyant vests are...

  7. 46 CFR 160.049-7 - Procedure for approval.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam § 160.049-7... be granted separately to each manufacturer for each unicellular plastic foam buoyant cushion...

  8. 46 CFR 160.049-7 - Procedure for approval.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam § 160.049-7... be granted separately to each manufacturer for each unicellular plastic foam buoyant cushion...

  9. 46 CFR 160.047-6 - Marking.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160.047-6 Marking. (a) Each buoyant vest must have the following information clearly... buoyant vests shall be sufficiently waterproof so that after 72 hours submergence in water, it...

  10. 46 CFR 160.047-5 - Inspections and tests. 1

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Kapok or Fibrous Glass, Adult... labeled buoyant vests shall— (1) Maintain quality control of the materials used, the manufacturing methods.... (b) Lot size and sampling. (1) A lot consists of 500 buoyant vests or fewer. (2) A new lot...

  11. 46 CFR 199.640 - Alternatives for cargo vessels in a specified service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... approval series 160.021 and six hand orange smoke distress signals approved under approval series 160.037... inflatable buoyant apparatus must be approved under approval series 160.010. Each lifefloat must be approved under approval series 160.027. (2) Stowage. Each buoyant apparatus, inflatable buoyant apparatus,...

  12. CONSEQUENCES OF NON-LINEAR DENSITY EFFECTS ON BUOYANCY AND PLUME BEHAVIOR

    EPA Science Inventory

    Aquatic plumes, as turbulent streams, grow by entraining ambient water. Buoyant plumes rise and dense ones sink, but, non-linear kinetic effects can reverse the buoyant force in mid-phenomenon. The class of nascent-density plumes begin as buoyant, upwardly accelerating plumes tha...

  13. Sipuleucel-T (Provenge(®))-Autopsy of an Innovative Paradigm Change in Cancer Treatment: Why a Single-Product Biotech Company Failed to Capitalize on its Breakthrough Invention.

    PubMed

    Jarosławski, Szymon; Toumi, Mondher

    2015-10-01

    Approved by the US Food and Drug Administration (FDA) in 2010, sipuleucel-T (Provenge(®)) was the first 'personalized' cancer vaccine for the treatment of prostate cancer in a metastatic, non-symptomatic population of 30,000 men in the USA. Sipuleucel-T is prepared individually for each patient and infused in three sessions over a period of 1 month. However, in 2015, Dendreon, the owner of sipuleucel-T, filed for bankruptcy. This opinion paper reviews the probable reasons this innovative product failed to achieve commercial success. PubMed and internet searches were performed focused on pricing, reimbursement, and market access. We found that sipuleucel-T's FDA approval was delayed by 3 years, reportedly because of the vaccine's new mechanism of action. Sipuleucel-T was cleared by the European Medicines Agency 2 years later, but other national agencies were not approached. It was priced at $US93,000 for a course of treatment, and this high price combined with the company's late securement of reimbursement for the vaccine by the US Centers for Medicare and Medicaid Services (CMS) resulted in another year's delay in accessing the market. Despite a positive recommendation by the National Comprehensive Cancer Network, sipuleucel-T's complex administration, high price, and uncertainty about the reimbursement status deterred doctors from prescribing the product. Furthermore, the vaccine's supply was limited during the first year of launch due to limited manufacturing capacity. In addition, two oral metastatic prostate cancer drugs with similar survival benefits reached the US market 1 and 2 years after sipuleucel-T. Also, even though Dendreon's market capitalization topped $US7.5 billion following the FDA's approval of sipuleucel-T, this value degraded gradually until the firm's bankruptcy 5 years later. We conclude that the bankruptcy of Dendreon was largely due to the delay in securing FDA approval and CMS coverage, as well as the high cost that had to be incurred by

  14. Sipuleucel-T (APC8015) for prostate cancer.

    PubMed

    So-Rosillo, Rosendo; Small, Eric J

    2006-09-01

    Sipuleucel-T (Provenge; APC8015; Dendreon Corp, WA, USA) is a novel immunotherapeutic cellular product, which includes autologous dendritic cells pulsed ex vivo with a recombinant fusion protein (PA2024) consisting of granulocyte macrophage colony-stimulating factor and prostatic acid phosphatase. Two Phase II trials in men with androgen-dependent biochemically relapsed prostate cancer have demonstrated a decrease in prostate-specific antigen and prolongation in prostate-specific antigen doubling time. In men with hormone-refractory prostate cancer, clinical trials have demonstrated both biological activity and clinical response to sipuleucel-T. Data from two Phase III trials in men with asymptomatic, metastatic hormone-refractory prostate cancer demonstrated an improved median overall survival in men who received sipuleucel-T compared with placebo. Clinical trials are ongoing or are being developed to evaluate sipuleucel-T in various prostate cancer disease states and in combination with other treatment modalities.

  15. Familial hypobetalipoproteinemia caused by a mutation in the apolipoprotein B gene that results in a truncated species of apolipoprotein B (B-31). A unique mutation that helps to define the portion of the apolipoprotein B molecule required for the formation of buoyant, triglyceride-rich lipoproteins.

    PubMed Central

    Young, S G; Hubl, S T; Smith, R S; Snyder, S M; Terdiman, J F

    1990-01-01

    Apolipoprotein B-100 has a crucial structural role in the formation of VLDL and LDL. Familial hypobetalipoproteinemia, a syndrome in which the concentration of LDL cholesterol in plasma is abnormally low, can be caused by mutations in the apo B gene that prevent the translation of a full-length apo B-100 molecule. Prior studies have revealed that truncated species of apo B [e.g., apo B-37 (1728 amino acids), apo B-46 (2057 amino acids)] can occasionally be identified in the plasma of subjects with familial hypobetalipoproteinemia; in each of these cases, the truncated apo B species has been a prominent protein component of VLDL. In this report, we describe a kindred with hypobetalipoproteinemia in which the plasma of four affected heterozygotes contained a unique truncated apo B species, apo B-31. Apolipoprotein B-31 is caused by the deletion of a single nucleotide in the apo B gene, and it is predicted to contain 1425 amino acids. Apolipoprotein B-31 is the shortest of the mutant apo B species to be identified in the plasma of a subject with hypobetalipoproteinemia. In contrast to longer truncated apo B species, apo B-31 was undetectable in the VLDL and the LDL; however, it was present in the HDL fraction and the lipoprotein-deficient fraction of plasma. The density distribution of apo B-31 in the plasma suggests the possibility that the amino-terminal 1425 amino acids of apo B-100 are sufficient to permit the formation and secretion of small, dense lipoproteins but are inadequate to support the formation of the more lipid-rich VLDL and LDL particles. Images PMID:2312735

  16. 46 CFR 160.052-3 - Materials-standard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam... incorporated in the finished product. (b) Unicellular plastic foam. The unicellular plastic foam shall be...

  17. 46 CFR 160.052-3 - Materials-standard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam... incorporated in the finished product. (b) Unicellular plastic foam. The unicellular plastic foam shall be...

  18. 46 CFR 160.060-3 - Materials-standard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... incorporated in the finished product. (b) Unicellular polyethylene foam. The unicellular polyethylene...

  19. 46 CFR 160.060-3 - Materials-standard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam... incorporated in the finished product. (b) Unicellular polyethylene foam. The unicellular polyethylene...

  20. BATHYMETRIC IRREGULARITIES, JET FORMATION, AND SUBSEQUENT MIXING PROCESSES

    EPA Science Inventory

    It is well known that bathymetric contours influence and steer currents and that irregularities in bathymetry contribute to the formation of aquatic non-buoyant jets and buoyant plumes. For example, bathymetric irregularities can channel flow through canyons or accelerate flow ov...

  1. 46 CFR 160.010-2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... of buoyant apparatus generally in use are the box-float type and the peripheral-body type defined in paragraphs (b) and (c) of this section. Box-float. Box-float is buoyant apparatus of a box-like...

  2. 46 CFR 28.130 - Survival craft equipment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... survival craft equipment must be of good quality, effective for the purpose it is intended to serve, and... “Limited Service”); or (3) SOLAS A Pack (formerly “Ocean Service”). (c) Each life float and buoyant... survival craft other than inflatable liferafts, life floats, inflatable buoyant apparatus, or...

  3. 46 CFR 160.048-1 - Incorporation by reference.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion, Fibrous Glass § 160.048-1... documents: (1) Military specification: MIL-B-2766—Batt, Fibrous Glass, Lifesaving Equipment. (2) Federal... issue in effect on the date kapok or fibrous glass buoyant cushions are manufactured, form a part...

  4. 46 CFR 160.049-2 - Types and sizes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Types and sizes. (a) Type. Buoyant cushions shall be of the box type, i.e., have top, bottom, and gusset. Pillow type cushions without a gusset are not acceptable. (b) Sizes. Buoyant cushions shall have not less than 225 square inches of top surface area, shall contain not less than 630 cubic inches of...

  5. 46 CFR 160.048-2 - Types and sizes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Types and sizes. (a) Types. Buoyant cushions shall be of the box type, i.e., have top, bottom and gusset. Pillow type cushions without a gusset are not acceptable. (b) Sizes. Buoyant cushions shall have not less than 225 square inches top surface area; widths and lengths which fall within the dimensions shown...

  6. 46 CFR 160.073-1 - Scope.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... float or buoyant apparatus so that the float or apparatus breaks free of a vessel that sinks in water... APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant Apparatus § 160.073-1 Scope. (a) This subpart contains requirements for a float-free link used for connecting a life float or...

  7. 46 CFR 160.073-1 - Scope.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... float or buoyant apparatus so that the float or apparatus breaks free of a vessel that sinks in water... APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant Apparatus § 160.073-1 Scope. (a) This subpart contains requirements for a float-free link used for connecting a life float or...

  8. 46 CFR 160.073-1 - Scope.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... float or buoyant apparatus so that the float or apparatus breaks free of a vessel that sinks in water... APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant Apparatus § 160.073-1 Scope. (a) This subpart contains requirements for a float-free link used for connecting a life float or...

  9. 46 CFR 160.073-1 - Scope.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... float or buoyant apparatus so that the float or apparatus breaks free of a vessel that sinks in water... APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant Apparatus § 160.073-1 Scope. (a) This subpart contains requirements for a float-free link used for connecting a life float or...

  10. 46 CFR 160.073-1 - Scope.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... float or buoyant apparatus so that the float or apparatus breaks free of a vessel that sinks in water... APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant Apparatus § 160.073-1 Scope. (a) This subpart contains requirements for a float-free link used for connecting a life float or...

  11. 46 CFR 160.048-1 - Incorporation by reference.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion, Fibrous Glass § 160.048-1... documents: (1) Military specification: MIL-B-2766—Batt, Fibrous Glass, Lifesaving Equipment. (2) Federal... issue in effect on the date kapok or fibrous glass buoyant cushions are manufactured, form a part...

  12. 46 CFR 160.048-1 - Incorporation by reference.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion, Fibrous Glass § 160.048-1... documents: (1) Military specification: MIL-B-2766—Batt, Fibrous Glass, Lifesaving Equipment. (2) Federal... issue in effect on the date kapok or fibrous glass buoyant cushions are manufactured, form a part...

  13. 46 CFR 160.047-2 - Model.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Model. 160.047-2 Section 160.047-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160.047-2 Model. Each buoyant...

  14. 46 CFR 160.064-2 - Types and models.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Types and models. 160.064-2 Section 160.064-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-2 Types and models. (a) Types. Water safety buoyant devices covered...

  15. 46 CFR 160.052-8 - Marking.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic Foam, Adult and Child § 160.052-8 Marking. (a) Each buoyant vest must have the following information clearly... vests shall be sufficiently waterproof so that after 72 hours submergence in water it will...

  16. 46 CFR 26.30-5 - Use.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF HOMELAND SECURITY UNINSPECTED VESSELS OPERATIONS Work Vest § 26.30-5 Use. (a) Approved buoyant work vests are considered to be items of safety apparel and may be carried aboard vessels to be worn by..., approved buoyant work vests shall not be accepted in lieu of any portion of the required number of...

  17. 46 CFR 169.556 - Work vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Work vests. 169.556 Section 169.556 Shipping COAST GUARD... Firefighting Equipment Additional Lifesaving Equipment § 169.556 Work vests. (a) Buoyant work vests carried.... (b) Approved buoyant work vests are items of safety apparel and may be carried aboard vessels to...

  18. 46 CFR 160.049-1 - Incorporation by reference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam § 160.049-1... Guard specifications: 160.055—Life Preservers, Unicellular Plastic Foam, Adult and Child. 164.015—Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shapes. (4) Military specifications....

  19. 46 CFR 160.064-4 - Marking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-4 Marking. (a) Each water safety buoyant device must have the following information clearly marked in waterproof lettering: (1) For... recreational boats and on uninspected commercial vessels less than 40 feet in length not carrying...

  20. 46 CFR 160.049-1 - Incorporation by reference.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Cushion Plastic Foam § 160.049-1... Guard specifications: 160.055—Life Preservers, Unicellular Plastic Foam, Adult and Child. 164.015—Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shapes. (4) Military specifications....

  1. 46 CFR 160.064-3 - Requirements. 1

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... arrangement of the buoyancy of devices intended to be worn on the body shall provide for flotation of the... mildew resistance. Buoyancy shall be provided by inherently buoyant material and shall not be dependent... buoyancy is provided by inherently buoyant material, the use of supplementary gas compartments,...

  2. 46 CFR 160.064-3 - Requirements. 1

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... arrangement of the buoyancy of devices intended to be worn on the body shall provide for flotation of the... mildew resistance. Buoyancy shall be provided by inherently buoyant material and shall not be dependent... buoyancy is provided by inherently buoyant material, the use of supplementary gas compartments,...

  3. 46 CFR 160.064-3 - Requirements. 1

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... arrangement of the buoyancy of devices intended to be worn on the body shall provide for flotation of the... mildew resistance. Buoyancy shall be provided by inherently buoyant material and shall not be dependent... buoyancy is provided by inherently buoyant material, the use of supplementary gas compartments,...

  4. 46 CFR 160.056-2 - Construction.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... construction shall be such as is accepted as good engineering practice in the case of the specific material... = Volume of buoyant material required in cubic feet. W = Weight of equipped boat, in pounds. d = Specific gravity of hull material. c = Density of buoyant material, in pounds per cubic foot....

  5. 46 CFR 160.056-2 - Construction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... construction shall be such as is accepted as good engineering practice in the case of the specific material... = Volume of buoyant material required in cubic feet. W = Weight of equipped boat, in pounds. d = Specific gravity of hull material. c = Density of buoyant material, in pounds per cubic foot....

  6. 46 CFR 160.047-4 - Construction.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... essentially consist of a vest-cut envelope containing compartments in which are enclosed pads of buoyant... comfortable fit to the bodies of various size wearers. (b) Envelope. The envelope or cover shall be cut to the... buoyant pad inserts, two front compartments and one back compartment, and reinforcing strips of the...

  7. Three-dimensional simulations of burning thermals

    NASA Astrophysics Data System (ADS)

    Aspden, Andy; Bell, John; Woosley, Stan

    2010-11-01

    Flame ignition in type Ia supernovae (SNe Ia) leads to isolated bubbles of burning buoyant fluid. As a bubble rises due to gravity, it becomes deformed by shear instabilities and transitions to a turbulent buoyant vortex ring. Morton, Taylor and Turner (1956) introduced the entrainment assumption, which can be applied to inert thermals. In this study, we use the entrainment assumption, suitably modified to account for burning, to predict the late-time asymptotic behaviour of these turbulent buoyant vortex rings in SNe Ia. The theory is validated against three- dimensional simulations with adaptive mesh refinement at effective resolutions up to 4096^3.

  8. Parametric study of modern airship productivity

    NASA Technical Reports Server (NTRS)

    Ardema, M. D.; Flaig, K.

    1980-01-01

    A method for estimating the specific productivity of both hybrid and fully buoyant airships is developed. Various methods of estimating structural weight of deltoid hybrids are discussed and a derived weight estimating relationship is presented. Specific productivity is used as a figure of merit in a parametric study of fully buoyant ellipsoidal and deltoid hybrid semi-buoyant vehicles. The sensitivity of results as a function of assumptions is also determined. No airship configurations were found to have superior specific productivity to transport airplanes.

  9. PROVENGE (Sipuleucel-T) in prostate cancer: the first FDA-approved therapeutic cancer vaccine.

    PubMed

    Cheever, Martin A; Higano, Celestia S

    2011-06-01

    Sipuleucel-T (PROVENGE; Dendreon) is the first therapeutic cancer vaccine to be approved by the U.S. Food and Drug Administration. In men who have metastatic castration-resistant prostate cancer with no or minimal symptoms, sipuleucel-T prolongs median survival by 4.1 months compared with results in those treated with placebo. At 3 years, the proportion of patients in the vaccine group who were alive was 50% higher than that in the control group (31.7% versus 21.7%, respectively). Sipuleucel-T, which is designed to elicit an immune response to prostatic acid phosphatase, uses the patient's own immune system to recognize and combat his cancer. Currently, no other agents are available that offer a survival benefit for this population of asymptomatic patients who have not been treated with chemotherapy, except for docetaxel (whose inherent toxicities often lead patients and physicians to delay administration until symptoms develop). Straightforward strategies to increase the efficacy of sipuleucel-T are likely to provide even greater benefit. The preclinical and clinical development of sipuleucel-T is reviewed, and approaches to enhance efficacy are considered herein.

  10. Sipuleucel-T for prostate cancer: the immunotherapy era has commenced.

    PubMed

    Buonerba, Carlo; Ferro, Matteo; Di Lorenzo, Giuseppe

    2011-01-01

    The US FDA recently approved sipuleucel-T (Provenge(®), Dendreon, Inc., WA, USA) on the grounds of the results reported by a Phase III trial, which are presented and discussed in detail in this article. This study was conducted in 512 metastatic castration-resistant prostate cancer patients randomized in a 2:1 ratio to receive either active therapy or placebo. Although no difference in time to progression was observed, a survival advantage was achieved, with a statistically meaningful 4.1-month improvement in median survival in the active arm with respect to the placebo arm (25.8 vs 21.7 months). In view of its favorable toxicity profile and manageable route of administration, sipuleucel-T is the ideal agent to be combined with other standard treatments, which include hormonal, cytotoxic and biological agents, and radiotherapy. Sipuleucel-T opens exciting new paradigms for prostate cancer and increases the possibility of survival prolongation for men with this deadly disease.

  11. Update: Immunological Strategies for Prostate Cancer

    PubMed Central

    Antonarakis, Emmanuel S.

    2014-01-01

    Prostate cancer is the second most common cause of cancer-related death in US men. Along with initial therapy using surgery, radiotherapy, or cryotherapy, hormonal therapy is the mainstay of treatment. For men with advanced (metastatic) disease, docetaxel-based chemotherapy is US Food and Drug Administration (FDA)-approved, and provides a significant survival advantage. This relative paucity of treatment options drives an ongoing quest for additional treatment modalities; among these is immunotherapy. The concept that prostate cancer is a malignancy that can be targeted by the immune system may seem counterintuitive; certainly kidney cancer and melanoma are more traditionally thought of as immune responsive cancers. However, prostate cancer arises in a relatively unique organ and may express a number of proteins (antigens) against which an immune response can be generated. More importantly, several of these agents have now demonstrated a significant survival benefit in randomized controlled clinical trials, and one agent in particular (Sipuleucel-T, Dendreon Corporation, Seattle, WA) could be FDA-approved in 2010. This update summarizes recent clinical developments in the field of prostate cancer immunotherapy, with a focus on dendritic cell vaccines, virus-based vaccines, DNA-based vaccines, and cell-based vaccines. In addition, the notion of agents that target immune checkpoints is introduced. Enthusiasm for prostate cancer immunotherapy is founded upon its potential to mediate targeted, specific, tumor cell destruction without significant systemic toxicity; however, this has yet to be fully realized in the clinical arena. PMID:20425628

  12. Update: immunological strategies for prostate cancer.

    PubMed

    Drake, Charles G; Antonarakis, Emmanuel S

    2010-05-01

    Prostate cancer is the second most common cause of cancer-related death in US men. Along with initial therapy using surgery, radiotherapy, or cryotherapy, hormonal therapy is the mainstay of treatment. For men with advanced (metastatic) disease, docetaxel-based chemotherapy is US Food and Drug Administration (FDA)-approved, and provides a significant survival advantage. This relative paucity of treatment options drives an ongoing quest for additional treatment modalities; among these is immunotherapy. The concept that prostate cancer is a malignancy that can be targeted by the immune system may seem counterintuitive; certainly kidney cancer and melanoma are more traditionally thought of as immune responsive cancers. However, prostate cancer arises in a relatively unique organ and may express a number of proteins (antigens) against which an immune response can be generated. More importantly, several of these agents have now demonstrated a significant survival benefit in randomized controlled clinical trials, and one agent in particular (Sipuleucel-T, Dendreon Corporation, Seattle, WA) could be FDA-approved in 2010. This update summarizes recent clinical developments in the field of prostate cancer immunotherapy, with a focus on dendritic cell vaccines, virus-based vaccines, DNA-based vaccines, and cell-based vaccines. In addition, the notion of agents that target immune checkpoints is introduced. Enthusiasm for prostate cancer immunotherapy is founded upon its potential to mediate targeted, specific, tumor cell destruction without significant systemic toxicity; however, this has yet to be fully realized in the clinical arena.

  13. 46 CFR 25.30-20 - Fire extinguishing equipment required.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Bait wells. 2. Glove compartments. 3. Buoyant flotation material. 4. Open slatted flooring. 5. Ice... stowed when not in use to prevent it from rolling out of control under heavy sea conditions. (d)...

  14. 46 CFR 25.30-20 - Fire extinguishing equipment required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Bait wells. 2. Glove compartments. 3. Buoyant flotation material. 4. Open slatted flooring. 5. Ice... stowed when not in use to prevent it from rolling out of control under heavy sea conditions. (d)...

  15. 46 CFR 25.30-20 - Fire extinguishing equipment required.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Bait wells. 2. Glove compartments. 3. Buoyant flotation material. 4. Open slatted flooring. 5. Ice... stowed when not in use to prevent it from rolling out of control under heavy sea conditions. (d)...

  16. 46 CFR 25.30-20 - Fire extinguishing equipment required.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... Bait wells. 2. Glove compartments. 3. Buoyant flotation material. 4. Open slatted flooring. 5. Ice... stowed when not in use to prevent it from rolling out of control under heavy sea conditions. (d)...

  17. 46 CFR 25.30-20 - Fire extinguishing equipment required.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Bait wells. 2. Glove compartments. 3. Buoyant flotation material. 4. Open slatted flooring. 5. Ice... stowed when not in use to prevent it from rolling out of control under heavy sea conditions. (d)...

  18. 46 CFR 164.015-2 - Types.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-2 Types. (a) Unicellular expanded polyvinyl chloride-acetate copolymer or synthetic rubber modified polyvinyl...

  19. 46 CFR 164.015-2 - Types.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-2 Types. (a) Unicellular expanded polyvinyl chloride-acetate copolymer or synthetic rubber modified polyvinyl...

  20. 46 CFR 160.060-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests. (a) General. The construction... must contain the following volume of unicellular polyethylene foam buoyant material, determined by...

  1. 46 CFR 160.060-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests. (a) General. The construction... must contain the following volume of unicellular polyethylene foam buoyant material, determined by...

  2. 46 CFR 160.060-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests. (a) General. The construction... must contain the following volume of unicellular polyethylene foam buoyant material, determined by...

  3. 46 CFR 160.060-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests. (a) General. The construction... must contain the following volume of unicellular polyethylene foam buoyant material, determined by...

  4. 46 CFR 160.060-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests. (a) General. The construction... must contain the following volume of unicellular polyethylene foam buoyant material, determined by...

  5. 46 CFR 161.012-1 - Scope.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... APPROVAL ELECTRICAL EQUIPMENT Personal Flotation Device Lights § 161.012-1 Scope. (a) This subpart... approving personal flotation device lights fitted on Coast Guard approved life preservers, buoyant vests, and other personal flotation devices. (b)...

  6. 46 CFR 160.073-10 - Construction and performance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant... permanently secured. (b) The breaking strength of each link must be between: (1) 450 N (100 lb.) and 600...

  7. 46 CFR 180.175 - Survival craft equipment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... certified to be resistant to deterioration from ultraviolet light; and (iv) Be stowed in such a way that it... buoyant apparatus by a 10 mm (3/8 inch) lanyard, resistant to deterioration from ultraviolet light, and...

  8. 46 CFR 180.175 - Survival craft equipment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... certified to be resistant to deterioration from ultraviolet light; and (iv) Be stowed in such a way that it... buoyant apparatus by a 10 mm (3/8 inch) lanyard, resistant to deterioration from ultraviolet light, and...

  9. 46 CFR 180.175 - Survival craft equipment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... certified to be resistant to deterioration from ultraviolet light; and (iv) Be stowed in such a way that it... buoyant apparatus by a 10 mm (3/8 inch) lanyard, resistant to deterioration from ultraviolet light, and...

  10. 46 CFR 180.175 - Survival craft equipment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... certified to be resistant to deterioration from ultraviolet light; and (iv) Be stowed in such a way that it... buoyant apparatus by a 10 mm (3/8 inch) lanyard, resistant to deterioration from ultraviolet light, and...

  11. GELCO 200

    EPA Pesticide Factsheets

    Technical product bulletin: this miscellaneous oil spill control agent is a solidifier used in cleanups. Can be applied on salt or fresh water or on land. It encapsulates and solidifies oil or other hydrocarbon, and remains buoyant after total saturation.

  12. Mantle Dynamics, Early Reservoir Formation and Degassing of the Martian Interior

    NASA Astrophysics Data System (ADS)

    Breuer, D.; Plesa, A.-C.; Grott, M.; Morschhauser, A.

    2014-11-01

    Inefficient volcanic outgassing of the interior supports the hypothesis that rather than being warm-and-wet, the martian climate was probably cold-and-wet. The formation of a buoyant depleted mantle layer prevents efficient outgassing of water.

  13. CIAGENT

    EPA Pesticide Factsheets

    Technical product bulletin: formerly CHEAP INSURANCE, PETRO-CAPTURE, this miscellaneous oil spill control agent used in cleanups encapsulates and solidifies oil, remaining buoyant. Also available in oil absorbent, water repellant booms and pillows.

  14. 46 CFR 164.015-2 - Types.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-2 Types. (a..., polymer or copolymer plastic foam shall be of three types as follows: Type A—for life preservers,...

  15. 46 CFR 164.015-4 - Inspections and tests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-4 Inspections and tests. (a) General. Unicellular plastic foam to be used in a finished product subject...

  16. 46 CFR 97.34-15 - Shipboard stowage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Vests § 97.34-15 Shipboard stowage. (a) The approved buoyant work vests shall be stowed separately from the regular stowage of approved life preservers. (b) The locations for the stowage of work vests...

  17. 46 CFR 160.073-10 - Construction and performance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Float-Free Link or Life Floats and Buoyant... permanently secured. (b) The breaking strength of each link must be between: (1) 450 N (100 lb.) and 600...

  18. 46 CFR 160.047-6 - Marking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... buoyant vests shall be sufficiently waterproof so that after 72 hours submergence in water, it will... Note: By 79 FR 56499, Sept. 22, 2014, § 160.047-6(a) was amended by removing the words “Type...

  19. 46 CFR 164.015-2 - Types.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-2 Types. (a..., polymer or copolymer plastic foam shall be of three types as follows: Type A—for life preservers,...

  20. Sedimentation Of Oil-MIneral Aggregates For Remediation Of Vegetable Oil Spills

    EPA Science Inventory

    A response alternative for floating vegetable oil spills based on sedimentation of negatively buoyant oil-mineral aggregrates followed by anaerobic biodegradation in the sediments is under investigation. Sedimentation of floating canola oil by interaction with montmorillonite wa...

  1. 46 CFR 160.064-6 - Examinations, tests and inspections.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... labeled water safety buoyant devices shall maintain quality control of the materials used, manufacturing... or materials entering into construction or final assemblies, for further examinations, inspections... 160.064-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT,...

  2. 46 CFR 164.013-6 - Production tests, inspections, and marking.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant... shall provide in-plant quality control of polyethylene foam in accordance with the requirements of § 164... responsibility for quality control over the production of the foam....

  3. 46 CFR 164.013-6 - Production tests, inspections, and marking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant... shall provide in-plant quality control of polyethylene foam in accordance with the requirements of § 164... responsibility for quality control over the production of the foam....

  4. 46 CFR 164.013-6 - Production tests, inspections, and marking.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant... shall provide in-plant quality control of polyethylene foam in accordance with the requirements of § 164... responsibility for quality control over the production of the foam....

  5. 46 CFR 164.013-6 - Production tests, inspections, and marking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant... shall provide in-plant quality control of polyethylene foam in accordance with the requirements of § 164... responsibility for quality control over the production of the foam....

  6. 46 CFR 160.064-6 - Examinations, tests and inspections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... labeled water safety buoyant devices shall maintain quality control of the materials used, manufacturing... or materials entering into construction or final assemblies, for further examinations, inspections... 160.064-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT,...

  7. 46 CFR 160.064-6 - Examinations, tests and inspections.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... labeled water safety buoyant devices shall maintain quality control of the materials used, manufacturing... or materials entering into construction or final assemblies, for further examinations, inspections... 160.064-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT,...

  8. 46 CFR 164.013-6 - Production tests, inspections, and marking.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant... shall provide in-plant quality control of polyethylene foam in accordance with the requirements of § 164... responsibility for quality control over the production of the foam....

  9. 46 CFR 164.015-2 - Types.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-2 Types. (a..., polymer or copolymer plastic foam shall be of three types as follows: Type A—for life preservers,...

  10. 46 CFR 199.640 - Alternatives for cargo vessels in a specified service.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... distress signals that meet the requirements of § 199.60, six hand red flare distress signals approved under... stowed to prevent shifting with easily detached lashings. (3) Marking. Each buoyant apparatus...

  11. 46 CFR 160.049-4 - Construction and workmanship.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... is to provide buoyancy to aid a person in keeping afloat in the water. Buoyant cushions providing less than 20 pounds buoyancy or less than 2 inches in thickness will not be acceptable. (b) Cover....

  12. 46 CFR 160.049-4 - Construction and workmanship.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... is to provide buoyancy to aid a person in keeping afloat in the water. Buoyant cushions providing less than 20 pounds buoyancy or less than 2 inches in thickness will not be acceptable. (b) Cover....

  13. Measurements and implications of vortex motions using two flow-visualization techniques

    NASA Technical Reports Server (NTRS)

    Delisi, Donald P.; Greene, George C.

    1990-01-01

    The present comparative study of two different, but complementary flow-visualization techniques, which yield different interpretations of vortex-migration distance and lifetime, gives attention to the difficulty of determining vortex evolution and lifetime from flow-visualization measurements. The techniques involved the release of a fluorescent dye and of neutrally buoyant particles in a water-filled towing tank. Vortices are found to migrate farther, and last longer, when visualized with neutrally buoyant particles rather than with dyes.

  14. LP/SV Bladder Buoyancy Test Comparison

    DTIC Science & Technology

    2011-07-01

    The buoyant force of the British MK 30 LCX is also unknown; however, this flotation device utilizes a large bladder and may replace the LP/SV. Aim...following inflation using a 45g CO2 canister. Conclusion: In all trials, both flotation devices produced buoyant forces greater that 35 lbs. The British...2. The British use a very similar aircrew flotation device called the MK 30 LCX. It differs from the currently used LP/SV because it utilizes a

  15. Investigation of the free flow electrophoretic process. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    Weiss, R. A.; Lanham, J. W.; Richman, D. W.; Walker, C. D.

    1979-01-01

    The effect of gravity on the free flow electrophoretic process was investigated. The demonstrated effects were then compared with predictions made by mathematical models. Results show that the carrier buffer flow was affected by gravity induced thermal convection and that the movement of the separating particle streams was affected by gravity induced buoyant forces. It was determined that if gravity induced buoyant forces were included in the mathematical models, then effective predictions of electrophoresis chamber separation performance were possible.

  16. Entrainment Descriptions for Mathematical Modeling of Pumped-Storage Inflows in Reservoirs.

    DTIC Science & Technology

    1985-10-01

    demonstrated that the entrainment description can be ., one of the most important inputs to a PS reservoir simulation model. ..... Therefore, adequate...discharged into arbitrary stratifica- ............. tion. The results were then reduced to a form suitable for inclusion into reservoir simulation models...integral buoyant jet model, as adapted to the reservoir simulation code, is referred to as subroutine SBJET (Strongly Buoyant JET). 26. Fan and

  17. Testing Experimental Compounds against Leishmaniasis in Laboratory Animal Model Systems.

    DTIC Science & Technology

    1983-09-01

    buoyant density analysis, monoclonal antibody typ- ing, and infectivity for sandflies . 2. In Vivo Screening a. Visceral Leishmaniasis Six groups of 6...the case in "pian bois" where vectors are anthoprophilic and multiple lesions (>0) abound (37). Whether environmental temperature has any effect upon...buoyant density, iso-enzymes, reaction with monoclonal antibody and development in sandflies (#3). Each of these was grown in 250 ml BA flasks overlaid

  18. Feasibility study of modern airships, phase 2. Volume 1: Heavy lift airship vehicle. Book 1: Overall study results

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A Heavy Lift Airship combining buoyant lift derived from a conventional helium-filled non-rigid airship hull with propulsive lift derived from conventional helicopter rotors was investigated. The buoyant lift essentially offsets the empty weight of the vehicle; thus the rotor thrust is available for useful load and to maneuver and control the vehicle. Such a vehicle is capable of providing a quantum increase in current vertical lifting capability. Certain critical deficiencies of past airships are significantly minimized or eliminated.

  19. Operational considerations for the airship in short-haul transportation

    NASA Technical Reports Server (NTRS)

    Walker, C. D.

    1975-01-01

    The airship's problems and the possibilities for their solution in a short-haul transportation environment are surveyed. The problems are derived from both past experience and envisioned operation. Problems relative to both fully buoyant and semi-buoyant configurations are considered and their origins in principle discussed. Also addressed in this paper are the state-of-the-art technologies with the potential of providing answers to the airship's operational difficulties.

  20. Translational Approaches towards Cancer Gene Therapy: Hurdles and Hopes

    PubMed Central

    Barar, Jaleh; Omidi, Yadollah

    2012-01-01

    Introduction Of the cancer gene therapy approaches, gene silencing, suicide/apoptosis inducing gene therapy, immunogene therapy and targeted gene therapy are deemed to sub-stantially control the biological consequences of genomic changes in cancerous cells. Thus, a large number of clinical trials have been conducted against various malignancies. In this review, we will discuss recent translational progresses of gene and cell therapy of cancer. Methods Essential information on gene therapy of cancer were reviewed and discussed towards their clinical translations. Results Gene transfer has been rigorously studied in vitro and in vivo, in which some of these gene therapy endeavours have been carried on towards translational investigations and clinical applications. About 65% of gene therapy trials are related to cancer therapy. Some of these trials have been combined with cell therapy to produce personalized medicines such as Sipuleucel-T (Provenge®, marketed by Dendreon, USA) for the treatment of asymptomatic/minimally symptomatic metastatic hormone-refractory prostate cancer. Conclusion Translational approach links two diverse boundaries of basic and clinical researches. For successful translation of geno-medicines into clinical applications, it is essential 1) to have the guidelines and standard operating procedures for development and application of the genomedicines specific to clinically relevant biomarker(s); 2) to conduct necessary animal experimental studies to show the “proof of concept” for the proposed genomedicines; 3) to perform an initial clinical investigation; and 4) to initiate extensive clinical trials to address all necessary requirements. In short, translational researches need to be refined to accelerate the geno-medicine development and clinical applications. PMID:23678451

  1. Steady advance of stem cell therapies: report from the 2011 World Stem Cell Summit, Pasadena, California, October 3-5.

    PubMed

    Swan, Melanie

    2011-12-01

    Stem cell research and related therapies (including regenerative medicine and cellular therapies) could have a significant near-term impact on worldwide public health and aging. One reason is the industry's strong linkage between policy, science, industry, and patient advocacy, as was clear in the attendance and programming at the 7(th) annual World Stem Cell Summit held in Pasadena, California, October 3-5, 2011. A special conference session sponsored by the SENS Foundation discussed how stem cell therapies are being used to extend healthy life span. Stem cells are useful not only in cell-replacement therapies, but also in disease modeling, drug discovery, and drug toxicity screening. Stem cell therapies are currently being applied to over 50 diseases, including heart, lung, neurodegenerative, and eye disease, cancer, and human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). Dozens of companies are developing therapeutic solutions that are in different stages of clinical use and clinical trials. Some high-profile therapies include Dendreon's Provenge for prostate cancer, Geron's first-ever embryonic stem cell trials for spinal cord injury, Fibrocell's laViv cellular therapy for wrinkles, and well-established commercial skin substitutes (Organogenesis' Apligraf and Advanced BioHealing's Dermagraft). Stem cell policy issues under consideration include medical tourism, standards for large-scale stem cell manufacturing, and lingering ethical debates over the use of embryonic stem cells. Contemporary stem cell science advances include a focus on techniques for the direct reprogramming of cells from one lineage to another without returning to pluripotency as an intermediary step, improved means of generating and characterizing induced pluripotent cells, and progress in approaches to neurodegenerative disease.

  2. A Lighter-Than-Air System Enhanced with Kinetic Lift

    NASA Technical Reports Server (NTRS)

    Spearman, M. Leroy

    2002-01-01

    A hybrid airship system is proposed in which the buoyant lift is enhanced with kinetic lift. The airship would consist of twin hulls in which the buoyant gas is contained. The twin hulls would be connected in parallel by a wing having an airfoil contour. In forward flight, the wing would provide kinetic lift that would add to the buoyant lift. The added lift would permit a greater payload/altitude combination than that which could be supported by the buoyant lift alone. The buoyant lift is a function of the volume of gas and the flight altitude. The kinetic lift is a function of the airfoil section, wing area, and the speed and altitude of flight. Accordingly there are a number of factors that can be manipulated to arrive at a particular design. Particular designs could vary from small, lightweight systems to very large, heavy-load systems. It will be the purpose of this paper to examine the sensitivity of such a design to the several variables. In addition, possible uses made achievable by such a hybrid system will be suggested.

  3. Distribution and composition of hydrothermal plume particles from the ASHES Vent Field at Axial Volcano, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Feely, R. A.; Geiselman, T. L.; Baker, E. T.; Massoth, G. J.; Hammond, S. R.

    1990-08-01

    In 1986 and 1987, buoyant and neutrally buoyant hydrothermal plume particles from the ASHES vent field within Axial Volcano were sampled to study their variations in composition with height above the seafloor. Individual mineral phases were identified using standard X ray diffraction procedures. Elemental composition and particle morphologies were determined by X ray fluorescence spectrometry and scanning electron microscopy/X ray energy spectrometry techniques. The vent particles were primarily composed of sphalerite, anhydrite, pyrite, pyrrhotite, chalcopyrite, barite, hydrous iron oxides, and amorphous silica. Grain size analyses of buoyant plume particles showed rapid particle growth in the first few centimeters above the vent orifice, followed by differential sedimentation of the larger sulfide and sulfate minerals out of the buoyant plume. The neutrally buoyant plume consisted of a lower plume, which was highly enriched in Fe, S, Zn, and Cu, and an upper plume, which was highly enriched in Fe and Mn. The upper plume was enriched in Fe and Mn oxyhydroxide particles, and the lower plume was enriched in suspended sulfide particles in addition to the Fe and Mn oxyhydroxide particles. The chemical data for the water column particles indicate that chemical scavenging and differential sedimentation processes are major factors controlling the composition of the dispersing hydrothermal particles. Short-term sediment trap experiments indicate that the fallout from the ASHES vent field is not as large as some of the other vent fields on the Juan de Fuca Ridge.

  4. Water-supported wind actuated power generating assembly

    SciTech Connect

    Hoar, R.A.

    1982-02-23

    A counterweighted elongate buoyant body that floats on the surface of the sea or a lake has at least one sail supporting mast extending upwardly therefrom as well as vanes that tend to maintain the sails substantially normal to the direction of movement of the wind. The buoyant body is by frame means maintained within the confines of a circular series of piles. The counterweight and means for pivoting each sail from a position normal to the direction of the wind to substantially parallel thereto cooperate to impart a transverse rocking motion to the buoyant body that has an eccentric transverse arcuate member depending therefrom that is engaged by a pair of rollers, as the transverse member moves relative to the pair of rollers a bellows is receprocated upwardly and downwardly to draw water into and discharge it from a check valve controlled confined space to a reservoir situated at a substantial distance above the surface of the body of water. Water discharges by gravity from the reservoir to a turbine or the like to power a generator to produce electricity for power purposes. Power means pivot the sails substantially parallel to the direction of the wind after the latter has rolled the buoyant body to a first position. The counterweight then rolls the buoyant body to a second position where upon the power means pivot the sails to positions substantially normal to the direction of the wind to start another power generating cycle.

  5. A new conceptual model of convection

    SciTech Connect

    Walcek, C.

    1995-09-01

    Classical cumulus parameterizations assume that cumulus clouds are entraining plumes of hot air rising through the atmosphere. However, ample evidence shows that clouds cannot be simulated using this approach. Dr. Walcek suggests that cumulus clouds can be reasonably simulated by assuming that buoyant plumes detrain mass as they rise through the atmosphere. Walcek successfully simulates measurements of tropical convection using this detraining model of cumulus convection. Comparisons with measurements suggest that buoyant plumes encounter resistance to upward movement as they pass through dry layers in the atmosphere. This probably results from turbulent mixing and evaporation of cloud water, which generates negatively buoyant mixtures which detrain from the upward moving plume. This mass flux model of detraining plumes is considerably simpler than existing mass flux models, yet reproduces many of the measured effects associated with convective activity. 1 fig.

  6. The migration of fluid droplets and their interactions in a thermal gradient

    NASA Technical Reports Server (NTRS)

    Subramanian, R. S.; Wilcox, W. R.

    1979-01-01

    When materials are processed in free fall, buoyant forces will be substantially reduced. Thus, the buoyant migration of droplets and bubbles which normally occurs on earth is expected to be overshadowed by migration due to other mechanisms in space processing. In particular, capillary forces on droplets due to the variation of interfacial tension around their periphery will play a significant role in governing their motion in space. While such interfacial tension gradients can be caused by thermal, compositional, and/or electrical gradients in the continuous phase, thermal gradients are convenient to use in controlled experimentation. On earth, due to interference from buoyant effects, it is difficult to study thermocapillary migration in sufficient detail. Also, the effects of a thermal gradient on the interactions among droplets are hard to study on Earth. Thus, an orbital facility for conducting experiments on the migration and interactions of fluid droplets in a continuous phase due to the action of a thermal gradient appears attractive.

  7. Computer aided airship design

    NASA Technical Reports Server (NTRS)

    Davis, S. J.; Rosenstein, H.

    1975-01-01

    The Comprehensive Airship Sizing and Performance Computer Program (CASCOMP) is described which was developed and used in the design and evaluation of advanced lighter-than-air (LTA) craft. The program defines design details such as engine size and number, component weight buildups, required power, and the physical dimensions of airships which are designed to meet specified mission requirements. The program is used in a comparative parametric evaluation of six advanced lighter-than-air concepts. The results indicate that fully buoyant conventional airships have the lightest gross lift required when designed for speeds less than 100 knots and the partially buoyant concepts are superior above 100 knots. When compared on the basis of specific productivity, which is a measure of the direct operating cost, the partially buoyant lifting body/tilting prop-rotor concept is optimum.

  8. Feasibility of modern airships - Design definition and performance of selected concepts

    NASA Technical Reports Server (NTRS)

    Huston, R. R.; Ardema, M. D.

    1977-01-01

    Three promising modern airship system concepts and their associated missions were studied: (1) a heavy-lift airship, employing a nonrigid hull and a significant amount of rotor lift, used for short-range transporting and positioning of heavy military and civil payloads; (2) a VTOL (vertical take-off and landing), metal-clad, partially buoyant airship used as a short-haul commercial transport; (3) a fully-buoyant airship used for long-endurance Navy missions. The heavy-lift airship concept offers a dramatic increase in vertical lift capability over existing systems at significantly lower costs per ton-mile. The VTOL airship transport concept appears to be economically competititve with other VTOL aircraft concepts but can attain significantly lower noise levels. The fully-buoyant airship concept can provide an airborne platform with long endurance that satisfies many Navy mission requirements.

  9. Feasibility study of modern airships. Phase 2: Executive summary

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A feasibility study of modern airships has been completed. Three promising modern airship systems' concepts and their associated missions were studied; (1) a heavy-lift airship, employing a non-rigid hull and a significant amount of rotor lift, used for short-range transport and positioning of heavy military and civil payloads, (2) a VTOL (vertical take-off and landing), metalclad, partially buoyant airship used as a short-haul commercial transport; and (3) a class of fully-buoyant airships used for long-endurance Navy missions. The heavy-lift airship concept offers a substantial increase in vertical lift capability over existing systems and is projected to have lower total operating costs per ton-mile. The VTOL airship transport concept appears to be economically competitive with other VTOL aircraft concepts but can attain significantly lower noise levels. The fully-buoyant airship concept can provide an airborne platform with long endurance that satisfies many Navy mission requirements.

  10. Mass and density measurements of live and dead Gram-negative and Gram-positive bacterial populations.

    PubMed

    Lewis, Christina L; Craig, Caelli C; Senecal, Andre G

    2014-06-01

    Monitoring cell growth and measuring physical features of food-borne pathogenic bacteria are important for better understanding the conditions under which these organisms survive and proliferate. To address this challenge, buoyant masses of live and dead Escherichia coli O157:H7 and Listeria innocua were measured using Archimedes, a commercially available suspended microchannel resonator (SMR). Cell growth was monitored with Archimedes by observing increased cell concentration and buoyant mass values of live growing bacteria. These growth data were compared to optical density measurements obtained with a Bioscreen system. We observed buoyant mass measurements with Archimedes at cell concentrations between 10(5) and 10(8) cells/ml, while growth was not observed with optical density measurements until the concentration was 10(7) cells/ml. Buoyant mass measurements of live and dead cells with and without exposure to hydrogen peroxide stress were also compared; live cells generally had a larger buoyant mass than dead cells. Additionally, buoyant mass measurements were used to determine cell density and total mass for both live and dead cells. Dead E. coli cells were found to have a larger density and smaller total mass than live E. coli cells. In contrast, density was the same for both live and dead L. innocua cells, while the total mass was greater for live than for dead cells. These results contribute to the ongoing challenge to further develop existing technologies used to observe cell populations at low concentrations and to measure unique physical features of cells that may be useful for developing future diagnostics.

  11. Are Brazil Nuts Attractive?

    NASA Astrophysics Data System (ADS)

    Sanders, Duncan A.; Swift, Michael R.; Bowley, R. M.; King, P. J.

    2004-11-01

    We present event-driven simulation results for single and multiple intruders in a vertically vibrated granular bed. Under our vibratory conditions, the mean vertical position of a single intruder is governed primarily by a buoyancylike effect. Multiple intruders also exhibit buoyancy governed behavior; however, multiple neutrally buoyant intruders cluster spontaneously and undergo horizontal segregation. These effects can be understood by considering the dynamics of two neutrally buoyant intruders. We have measured an attractive force between such intruders which has a range of five intruder diameters, and we provide a mechanistic explanation for the origins of this force.

  12. Models for some aspects of atmospheric vortices

    NASA Technical Reports Server (NTRS)

    Deissler, R. G.

    1977-01-01

    A frictionless adiabatic model is used to study the growth of random vortices in an atmosphere with buoyant instability and vertical wind shear, taking account of the effects of axial drag, heat transfer and precipitation-induced downdrafts. It is found that downdrafts of tornadic magnitude may occur in negatively buoyant columns. The radial-inflow velocity required to maintain a given maximum tangential velocity in a tornado is determined by using a turbulent vortex model. A tornado model which involves a rotating parent cloud as well as buoyancy and precipitation effects is also discussed.

  13. LTA structures and materials technology

    NASA Technical Reports Server (NTRS)

    Mayer, N. J.

    1975-01-01

    The state-of-the-art concerning structures and materials technology is reviewed. It is shown that many present materials developments resulting from balloon and aircraft research programs can be applied to new concepts in LTA vehicles. Both buoyant and semi-buoyant vehicles utilize similar approaches to solving structural problems and could involve pressurized non-rigid and unpressurized rigid structures. System designs common to both and vital to structural integrity include much of the past technology as well. Further research is needed in determination of structural loads, especially in future design concepts.

  14. Anaerobic reduction of elemental sulfur by Chromatium vinosum and Beggiatoa alba

    NASA Technical Reports Server (NTRS)

    Schmidt, T. M.

    1985-01-01

    The effect of sulfur globules on the buoyant density of Chromatium vinosum and Beggiatoa alba was examined. The potential use of sulfur as a terminal electron acceptor in the anaerobic metabolism of Beggiatoa alba is also examined. The effect of the reduction of intracellular sulfur was investigated during dark metabolism on the buoyant density of C. vinosum. It is hypothesized from the results that the sulfur reduction to sulfide is part of an anaerobic energy operating system. Carbon stored as PHB can be oxidized with the concomitant reduction of sulfur to sulfide.

  15. Diapiric flow at subduction zones: a recipe for rapid transport.

    PubMed

    Hall, P S; Kincaid, C

    2001-06-29

    Recent geochemical studies of uranium-thorium series disequilibrium in rocks from subduction zones require magmas to be transported through the mantle from just above the subducting slab to the surface in as little as approximately 30,000 years. We present a series of laboratory experiments that investigate the characteristic time scales and flow patterns of the diapiric upwelling model of subduction zone magmatism. Results indicate that the interaction between buoyantly upwelling diapirs and subduction-induced flow in the mantle creates a network of low-density, low-viscosity conduits through which buoyant flow is rapid, yielding transport times commensurate with those indicated by uranium-thorium studies.

  16. LTA structures and materials technology. [airships

    NASA Technical Reports Server (NTRS)

    Mayer, N. J.

    1975-01-01

    The state-of-the-art concerning structures and materials technology is reviewed. It is shown that many present materials developments resulting from balloon and aircraft research programs can be applied to new concepts in LTA vehicles. Both buoyant and semi-buoyant vehicles will utilize similar approaches to solving structural problems and could involve pressurized non-rigid and unpressurized rigid structures. System designs common to both and vital to structural integrity will include much of the past technology as well. Further research is needed in determination of structural loads, especially in future design concepts.

  17. Technology update: Tethered aerostat structural design and material developments

    NASA Technical Reports Server (NTRS)

    Witherow, R. G.

    1975-01-01

    Requirements exist for an extremely stable, high performance, all-weather tethered aerostat system. This requirement has been satisfied by a 250,000 cubic foot captive buoyant vehicle as demonstrated by over a year of successful field operations. This achievement required significant advancements in several technology areas including composite materials design, aerostatics and aerodynamics, structural design, electro-mechanical design, vehicle fabrication and mooring operations. This paper specifically addresses the materials and structural design aspects of pressurized buoyant vehicles as related to the general class of Lighter Than Air vehicles.

  18. 46 CFR 160.064-7 - Recognized laboratory.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Recognized laboratory. 160.064-7 Section 160.064-7...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-7 Recognized laboratory. (a) A... laboratory. The following laboratories are recognized under § 159.010-7 of this part, to perform testing...

  19. 46 CFR 160.064-7 - Recognized laboratory.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Recognized laboratory. 160.064-7 Section 160.064-7...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-7 Recognized laboratory. (a) A... laboratory. The following laboratories are recognized under § 159.010-7 of this part, to perform testing...

  20. 46 CFR 160.064-7 - Recognized laboratory.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Recognized laboratory. 160.064-7 Section 160.064-7...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-7 Recognized laboratory. (a) A... laboratory. The following laboratories are recognized under § 159.010-7 of this part, to perform testing...

  1. 46 CFR 160.064-7 - Recognized laboratory.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Recognized laboratory. 160.064-7 Section 160.064-7...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-7 Recognized laboratory. (a) A... laboratory. The following laboratories are recognized under § 159.010-7 of this part, to perform testing...

  2. 46 CFR 160.064-7 - Recognized laboratory.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Recognized laboratory. 160.064-7 Section 160.064-7...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Marine Buoyant Devices § 160.064-7 Recognized laboratory. (a) A... laboratory. The following laboratories are recognized under § 159.010-7 of this part, to perform testing...

  3. 46 CFR 199.640 - Alternatives for cargo vessels in a specified service.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... strength of at least 6.7 kiloNewtons (1,500 pounds-force), or if the capacity of the buoyant apparatus or lifefloat is 50 persons or more, have a breaking strength of at least 13.4 kiloNewtons (3,000...

  4. 46 CFR 160.062-2 - Types.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an...

  5. 46 CFR 160.062-2 - Types.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an...

  6. 46 CFR 160.062-2 - Types.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an...

  7. 46 CFR 160.062-2 - Types.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an...

  8. 46 CFR 160.062-2 - Types.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an...

  9. 46 CFR 160.047-4 - Construction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... required to hold the wearer in an upright backward position with head and face out of water. The buoyant... center of the neck hole to the top of the vest as shown in Section J-J of the drawings. (c) Pad...

  10. Measurements of Vorticity Vectors in Couette Flow with the Vorticity Optical Probe

    DTIC Science & Technology

    1991-05-01

    Tables Companson ot Turbulence Microscales and Particle Characteristics ................. 2 Candidate M aterials...34The Kolmogorov microscales tor two flow conditions in water are summarized in Table 1. Table 1. Comparison of Turbulence Microscales and Particle...neutrally buoyant particle is included in the table for comparison. Note that for the most inten turbulence (Case 2). some small scale structure is

  11. How Stable Is Stable?

    ERIC Educational Resources Information Center

    Baehr, Marie

    1994-01-01

    Provides a problem where students are asked to find the point at which a soda can floating in some liquid changes its equilibrium between stable and unstable as the soda is removed from the can. Requires use of Newton's first law, center of mass, Archimedes' principle, stable and unstable equilibrium, and buoyant force position. (MVL)

  12. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    NASA Astrophysics Data System (ADS)

    Kukkonen, J.; Nikmo, J.; Sofiev, M.; Riikonen, K.; Petäjä, T.; Virkkula, A.; Levula, J.; Schobesberger, S.; Webber, D. M.

    2014-11-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US) in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500 and 800 m and between 200 and 700 m, using two alternative meteorological data sets. The corresponding observed injection heights of the aerosol particles measured using an airborne lidar (light detection and ranging) ranged from 250 to 600 m. For the prescribed burning experiment in Hyytiälä (Finland) in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements onboard an aeroplane. However, the agreement between modelled and measured results substantially depends on how the properties of the source term are evaluated, especially regarding the convective heat fluxes from the fire. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i) the source terms for the atmospheric dispersion computations and (ii) the relevant vertical meteorological profiles.

  13. 46 CFR 28.120 - Survival craft.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Lakes, bays, sounds, warm waters; or Rivers, warm waters All None. Great Lakes, cold waters 10.97 meters...; or rivers, cold water 10.97 meters (36 feet) or more in length Buoyant apparatus. Inside Boundary Line, cold waters; or Lakes, bays, sounds, cold waters; or Rivers, cold water Less than 10.97...

  14. 46 CFR 180.204 - Survival craft-vessels operating on coastwise routes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... cold water must either: (1) Be provided with inflatable buoyant apparatus of an aggregate capacity that... other than wood certificated to operate on a coastwise route in cold water must be provided with life... operate on a coastwise route in warm water must be provided with life floats of an aggregate capacity...

  15. 46 CFR 180.205 - Survival craft-vessels operating on limited coastwise routes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... coastwise route in cold water must either: (1) Be provided with inflatable buoyant apparatus of an aggregate... on a limited coastwise route in cold water must be provided with life floats of an aggregate capacity... in warm water must be provided with life floats of an aggregate capacity that will accommodate...

  16. 46 CFR 160.052-2 - Size and model.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Size and model. 160.052-2 Section 160.052-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  17. 46 CFR 160.052-8 - Marking.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Marking. 160.052-8 Section 160.052-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  18. 46 CFR 160.052-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Construction-nonstandard vests. 160.052-6 Section 160.052-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest,...

  19. 46 CFR 160.052-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Construction-nonstandard vests. 160.052-6 Section 160.052-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest,...

  20. 46 CFR 160.052-8 - Marking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Marking. 160.052-8 Section 160.052-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  1. 46 CFR 160.052-4 - Materials-nonstandard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Materials-nonstandard vests. 160.052-4 Section 160.052-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  2. 46 CFR 160.052-6 - Construction-nonstandard vests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Construction-nonstandard vests. 160.052-6 Section 160.052-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest,...

  3. 46 CFR 164.015-3 - Material and workmanship.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-3 Material and workmanship. (a) The unicellular plastic foam shall be all new material complying with the... values within the limits shown in Table 164.015-4(a). (b) The unicellular plastic foam shall be...

  4. 46 CFR 164.015-1 - Applicable specifications and standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Applicable specifications and standards. 164.015-1 Section 164.015-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant,...

  5. 46 CFR 160.052-2 - Size and model.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Size and model. 160.052-2 Section 160.052-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  6. 46 CFR 160.052-2 - Size and model.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Size and model. 160.052-2 Section 160.052-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  7. 46 CFR 160.052-8 - Marking.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Marking. 160.052-8 Section 160.052-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  8. 46 CFR 160.052-4 - Materials-nonstandard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Materials-nonstandard vests. 160.052-4 Section 160.052-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  9. 46 CFR 160.052-8 - Marking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Marking. 160.052-8 Section 160.052-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  10. 46 CFR 164.015-5 - Procedure for acceptance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-5 Procedure for acceptance. (a) Unicellular plastic foam is not subject to formal approval, but will be... unicellular plastic foam prior to being incorporated into finished products, or during the course...

  11. 46 CFR 164.015-3 - Material and workmanship.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-3 Material and workmanship. (a) The unicellular plastic foam shall be all new material complying with the... values within the limits shown in Table 164.015-4(a). (b) The unicellular plastic foam shall be...

  12. 46 CFR 164.015-5 - Procedure for acceptance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant, Sheet and Molded Shape § 164.015-5 Procedure for acceptance. (a) Unicellular plastic foam is not subject to formal approval, but will be... unicellular plastic foam prior to being incorporated into finished products, or during the course...

  13. 46 CFR 160.052-2 - Size and model.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Size and model. 160.052-2 Section 160.052-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Plastic...

  14. 46 CFR 164.015-1 - Applicable specifications and standards.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Applicable specifications and standards. 164.015-1 Section 164.015-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Plastic Foam, Unicellular, Buoyant,...

  15. Lateral Migration and Rotational Motion of Elliptic Particles in Planar Poiseuille Flow

    NASA Technical Reports Server (NTRS)

    Qi, Dewei; Luo, Li-Shi; Aravamuthan, Raja; Strieder, William; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    Simulations of elliptic particulate suspensions in the planar Poiseuille flow are performed by using the lattice Boltzmann equation. Effects of the multi-particle on the lateral migration and rotational motion of both neutrally and non-neutrally buoyant elliptic particles are investigated. Low and intermediate total particle volume fraction f(sub a) = 13%, 15%, and 40% are considered in this work.

  16. Mixing and Turbulence in a Flooding Coastal River

    DTIC Science & Technology

    2013-12-01

    mixing and entrainment in the buoyant plume (see, for example, Peters and Johns 2005). With their different physical and temporal scales, the...sediment suspension and dep- osition. However, the use of high-frequency four-beam acoustic Doppler current profilers allows the measurement, through

  17. 46 CFR 164.013-1 - Scope.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-1... inspection requirements for polyethylene foam used in the construction of personal flotation devices (PFDs... subpart 164.019 of this chapter. (b) All polyethylene foams accepted under this subpart are...

  18. 46 CFR 164.013-1 - Scope.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-1... inspection requirements for polyethylene foam used in the construction of personal flotation devices (PFDs... subpart 164.019 of this chapter. (b) All polyethylene foams accepted under this subpart are...

  19. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab... polyethylene foam shall be all new material complying with the requirements outlined in this specification. Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  20. 46 CFR 160.060-2 - Type and model.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Type and model. 160.060-2 Section 160.060-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  1. 46 CFR 164.013-7 - Marking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Marking. 164.013-7 Section 164.013-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...

  2. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab... polyethylene foam shall be all new material complying with the requirements outlined in this specification. Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  3. 46 CFR 160.050-3 - Materials.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... line. The grab line shall be 3/8-inch diameter polyethylene, polypropylene, or other suitable buoyant... for securing the grab line shall be 2-inch polyethylene, polypropylene, nylon, saran or other suitable synthetic material having a minimum breaking strength of 585 pounds. In addition, polyethylene...

  4. 46 CFR 160.060-9 - Recognized laboratory.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Recognized laboratory. 160.060-9 Section 160.060-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  5. 46 CFR 164.013-1 - Scope.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-1... inspection requirements for polyethylene foam used in the construction of personal flotation devices (PFDs... subpart 164.019 of this chapter. (b) All polyethylene foams accepted under this subpart are...

  6. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab... polyethylene foam shall be all new material complying with the requirements outlined in this specification. Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  7. 46 CFR 160.060-5 - Construction-standard vests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Construction-standard vests. 160.060-5 Section 160.060-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  8. 46 CFR 160.060-4 - Materials-nonstandard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Materials-nonstandard vests. 160.060-4 Section 160.060-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  9. 46 CFR 160.060-2 - Type and model.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Type and model. 160.060-2 Section 160.060-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  10. 46 CFR 164.013-4 - Samples submitted for acceptance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Samples submitted for acceptance. 164.013-4 Section 164.013-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab,...

  11. 46 CFR 164.013-7 - Marking.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Marking. 164.013-7 Section 164.013-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...

  12. 46 CFR 160.060-5 - Construction-standard vests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Construction-standard vests. 160.060-5 Section 160.060-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  13. 46 CFR 164.013-1 - Scope.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-1... inspection requirements for polyethylene foam used in the construction of personal flotation devices (PFDs... subpart 164.019 of this chapter. (b) All polyethylene foams accepted under this subpart are...

  14. 46 CFR 160.060-9 - Recognized laboratory.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Recognized laboratory. 160.060-9 Section 160.060-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  15. 46 CFR 164.013-4 - Samples submitted for acceptance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Samples submitted for acceptance. 164.013-4 Section 164.013-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab,...

  16. 46 CFR 160.060-4 - Materials-nonstandard vests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Materials-nonstandard vests. 160.060-4 Section 160.060-4 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene...

  17. 46 CFR 164.013-7 - Marking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Marking. 164.013-7 Section 164.013-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...

  18. 46 CFR 164.013-5 - Acceptance tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Acceptance tests. 164.013-5 Section 164.013-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...

  19. 46 CFR 164.013-3 - Material properties and workmanship.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab... polyethylene foam shall be all new material complying with the requirements outlined in this specification. Unicellular polyethylene foam must comply with the requirements of UL 1191, sections 24, 25, and 26 and...

  20. 46 CFR 164.013-2 - Incorporation by reference.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Incorporation by reference. 164.013-2 Section 164.013-2 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...