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1

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

PubMed

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 DN 1924, as well as other HLA-DR antibodies not being developed by Kirin. Previously, in May 1999, Dendreon and Kirin established a collaboration for the development of dendritic cell-based immunotherapeutics for cancer, including Sipuleucel-T. Under the agreement, Kirin would provide financial support for Dendreon's research on dendritic cells focused on developing immunotherapies for cancers most prevalent in Asia. Dendreon would retain US rights to products arising from the collaboration while Kirin would hold the rights to such immuno-therapeutics in Asia and Oceania. In August 2005, Dendreon signed an agreement to lease a commercial manufacturing facility in Hanover, New Jersey, USA. The company intends to develop the facility to meet anticipated clinical and commercial demands of Sipuleucel-T as well as other active immunotherapy product candidates. Dendreon and Diosynth Biotechnology (Akzo Nobel) have an agreement for the commercial production of the PA 2024 antigen component of Sipuleucel-T. In November 2003, Dendreon announced that Diosynth successfully manufactured PA 2024 on a commercial scale. In October 2001, Dendreon announced that Gambro Healthcare Inc. would provide a network of centres for cell collection to support commercial production and clinical development of various Dendreon vaccines, including Sipuleucel-T. Dendreon has outsourced its cell processing operations in Mountain View, California, USA to Progenitor Cell Therapy under an amended agreement signed in August 2002. This agreement is an expansion of an existing agreement, under which Progenitor provided Dendreon with cell-processing services through its facility in Hackensack, New Jersey, USA. The pivotal, two-stage, phase III trial (D9902 study) has been initiated at clinical sites in the US. The first stage of the trial (D9902A study) is a double-blind, placebo-controlled phase III trial designed to evaluate Sipuleucel-T in men with asymptomatic, metastatic, androgen-independent prostate cancer. The trial was originally designed to be the companion study to a previously completed

2006-01-01

2

Buoyant Force  

NSDL National Science Digital Library

This activity is a lab where students gather data on buoyant force and height of and object being submerged in two different types of fluids. The slope of the buoyant force and height is proportional to the density of the fluid. Students compare the densities of the fluids calculated with the actual densities.

Renae Garski, Bigfork High School, Bigfork, MN, based on an original activity from Science Workshop, p. 115

3

Serpentine Buoyant Cable Antenna.  

National Technical Information Service (NTIS)

The present invention relates to an improved buoyant cable antenna system. The system includes a buoyant cable transmission line segment and an antenna segment formed from a flexible memory structure comprised of at least one segment of coiled compression...

E. M. Gerhard

2006-01-01

4

Buoyant Cable Antenna System.  

National Technical Information Service (NTIS)

A buoyant cable system and method is provided with a flexible towed platform that may be deployed into the water from a submerged submarine. The flexible towed platform has a memory that returns to a selected shape after deployment. A presently preferred ...

E. M. Gerhard

2006-01-01

5

Buoyant plume calculations  

SciTech Connect

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.

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

1985-01-01

6

The diffusion of turbulent buoyant jets  

Microsoft Academic Search

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

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

1984-01-01

7

MERGING BUOYANT JETS IN A STRATIFIED CROSSFLOW  

EPA Science Inventory

Some of the results of an extensive series of experiments to study the characteristics of merging, horizontally discharged buoyant jets in a linearly density stratified current are summarized. The experiments were conducted in a towing tank to simulate conditions typical of ocean...

8

1Preliminary Instability in a buoyant chemical  

E-print Network

1Preliminary Instability in a buoyant chemical front driven by curvature Andrejs Treibergs May 23, 2006 Abstract We consider a model of a curvature dependent chemical reaction along a circular interface effects, pressure and gravity and combustion effects at the interface through the burning speed of a flame

Treibergs, Andrejs

9

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...

10

Instability threshold of a negatively buoyant fountain  

Microsoft Academic Search

Experimental simulations were carried out to investigate the onset of instability in negatively buoyant fountains by injecting\\u000a glycerin–water mixtures into silicon oil. The transition from a stable to an unstable fountain structure is primarily governed\\u000a by the Richardson number, and to a lesser extent, Reynolds number, viscosity ratio, Weber number and vent geometry. Transition\\u000a nominally occurs at a Ri = 1.0. For

Peter D. Friedman; Vidya D. Vadakoot; William J. Meyer; Steven Carey

2007-01-01

11

Baroclinic instability of a buoyant coastal current  

NASA Astrophysics Data System (ADS)

Classic models of baroclinic instability, notably the Eady model, depend on the Rossby (or Richardson) number as the sole non-dimensional parameter. Inclusion of a sloping bottom requires an additional parameter, the slope Burger number, Bu = ?Nf-1, where ? is the bottom slope. Numerical simulations of the evolution of instabilities along the edge of a coastally trapped buoyant flow suggest that the slope may help to stabilize the flow when the deformation radius is similar to or larger than the with of the buoyant flow, that is, the flow is stable when the slope Burger number is larger than about 0.3. In unstable cases, Bu < 0.3, baroclinic instabilities in the flow cause the isopycnals to relax, thereby increasing the local Burger number until the critical condition, Bu ? 0.3, is met. At this point the instabilities no longer grow in time, preventing further offshore buoyancy flux by the eddies. This final state corresponds approximately to the case where the slope of the ground is similar to the slope of the mean isopycnal surfaces. The nonlinear, three-dimensional numerical simulations are in basic agreement with one-dimensional linear stability analysis, with a few key exceptions. Notably, numerical simulations suggest that cross-shelf buoyancy fluxes are strongest in within the bottom boundary layer, showing a similar pattern to continental shelf waves in the vertical structure of current and tracer variability. Idealized simulations show a marked similarity to instabilities along the Mississippi/Atchafalaya plume front, as seen in observations and realistic regional models. These eddies have been shown to be important in Lagrangian transport of surface particles, notably oil spill trajectory prediction, and create patchiness in bottom dissolved oxygen distributions during periods of summertime seasonal hypoxia.

Hetland, Robert

2014-05-01

12

Dynamics of buoyant bubbles in clusters of galaxies  

E-print Network

We present a phenomenological model of the dynamics of buoyant bubbles in the atmosphere of a cluster of galaxies. The derived equations describe velocity, size, mass, temperature and density of the buoyant bubbles as functions of time based on several simple approximations. The constructed model is then used to interpret results of a numerical experiment of heating of the cluster core with buoyant bubbles in a hydrodynamical approximation (i.e. in the absence of magnetic fields, viscosity, and thermal diffusion). Based on the model parameters we discuss possible limitations of the numerical treatment of the problem, and highlight the main physical processes that govern the dynamics of bubbles in the intracluster medium.

Georgi Pavlovski; Christian R. Kaiser; Edward C. D. Pope

2007-09-12

13

Using buoyant mass to measure the growth of single cells  

E-print Network

We used a suspended microchannel resonator (SMR) combined with picoliter-scale microfluidic control to measure buoyant mass and determine the 'instantaneous' growth rates of individual cells. The SMR measures mass with ...

Godin, Michel

14

46 CFR 160.010-6 - Capacity of buoyant apparatus.  

Code of Federal Regulations, 2011 CFR

...following methods: (1) Final buoyancy of the buoyant apparatus in Newtons...divided by 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...

2011-10-01

15

46 CFR 160.010-6 - Capacity of buoyant apparatus.  

Code of Federal Regulations, 2013 CFR

...following methods: (1) Final buoyancy of the buoyant apparatus in Newtons...divided by 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...

2013-10-01

16

Behavior of buoyant moist plumes in turbulent atmospheres  

E-print Network

A widely applicable computational model of buoyant moist plumes in turbulent atmospheres has been constructed. To achieve this a one dimensional Planetary Boundary Layer (P.B.L.) model has been developed to account for ...

Hamza, Redouane

1981-01-01

17

Experiments on stability and oscillatory behavior of planar buoyant plumes  

Microsoft Academic Search

Experiments on the onset of buoyant instabilities leading to periodic formation of vortical structures in planar buoyant plumes of helium and helium\\/air mixtures injected into quiescent air are reported for a range of nozzle widths (w=20–70 mm), plume fluid densities (pure helium to that approaching air), and velocities at the nozzle exit. First, the plume parameters corresponding to the onset

B. M. Cetegen; Y. Dong; M. C. Soteriou

1998-01-01

18

Experiments on stability and oscillatory behavior of planar buoyant plumes  

Microsoft Academic Search

Experiments on the onset of buoyant instabilities leading to periodic formation of vortical structures in planar buoyant plumes of helium and helium\\/air mixtures injected into quiescent air are reported for a range of nozzle widths (w=20-70 mm), plume fluid densities (pure helium to that approaching air), and velocities at the nozzle exit. First, the plume parameters corresponding to the onset

B. M. Cetegen; Y. Dong; M. C. Soteriou

1998-01-01

19

Buoyant density separation of cells. I. The buoyant distribution of guinea pig bone marrow cells.  

PubMed

Guinea pig bone marrow cells were separated by buoyant density utilizing linear gradients of bovine serum albumin (BSA). It has finally become possible to characterize the cells present in the density fractions in terms of classical morphology. The development of the Cell Type computer program which calculates the percentages of the individual types of cells present in the fractions and their buoyant density distributions and plots the data has greatly facilitated and improved the accuracy of these studies. Approximately 40 cell types were observed in guinea pig bone marrow. Cells with definitive morphologies such as erythrocytes, the neutrophilic series, the binucleate blast megakaryocyte precursor and cells in mitosis band as virtually single peaks. Cells which are parts of continua or can easily be wrongly classified are found in multiple peaks. The small lymphocytes which are known to be polydisperse are found as five peaks. Because of the very strong benzidine staining by the glutaraldehyde-fixed hemoglobin, some of the erythroblasts were wrongly staged, resulting in a multimodal distribution. The presence of macrocytes further complicated these distributions. The rule that the younger cells are always less dense than the mature cells was adhered to in those cases where the cells could be definitively characterized, such as the neutrophilic series and the blasts. These results indicate that morphology is a good first approximation of reality. PMID:1127223

Leif, R C; Smith, S B; Dunlap, L A; Leif, S B

1975-05-01

20

Large Eddy Simulation of a Turbulent Buoyant Helium Philip Smith  

E-print Network

Large Eddy Simulation of a Turbulent Buoyant Helium Plume Philip Smith University of Utah 155 and environmental importance, including fires, subsea and atmospheric exhaust phenomena, gas releases and geothermal and validating simulation tools for numerical techniques such as Large Eddy Simulation (LES) for predictive use

Utah, University of

21

46 CFR 160.010-6 - Capacity of buoyant apparatus.  

Code of Federal Regulations, 2012 CFR

...is approved must be the lowest number determined by the following methods: (1) Final buoyancy of the buoyant apparatus in Newtons after the watertight integrity test as described in § 160.010-7 (e) and (f), divided by 145 (divided by 32...

2012-10-01

22

Buoyant Cable Antenna System and Method With Articulating Blocks.  

National Technical Information Service (NTIS)

A buoyant cable system and method is provided with a towed platform that is flexible for deployment into the water from a submerged submarine. The towed platform has a memory that returns to a selected shape after deployment. In one embodiment the biasing...

E. M. Gerhard

2006-01-01

23

APPLICATION OF BUOYANT MASS TRANSFER MEDIA TO HAZARDOUS MATERIAL SPILLS  

EPA Science Inventory

A prototype system was designed and developed to slurry buoyant activated carbon into a static body of water. The process was developed to remove spilled soluable hazardous compounds from a watercourse. In a simulated spill, up to 98% removal of Diazinon, an organophosphorus pest...

24

Flushing of a buoyant pollutant from an urban canyon  

NASA Astrophysics Data System (ADS)

We examine the wind driven flushing of a negatively buoyant pollutant from an urban canyon. We examine the rate at which a fluid of buoyancy g' is removed from a two dimensional urban canyon of width W formed by two buildings of height H and square cross section. The flushing is driven by a wind flow, of mean velocity U, normal to the axis of the canyon. A previous study of flushing of a neutrally buoyant fluid by Caton et al. (2003) showed that the mean concentration decayed exponentially with time indicating a steady exchange of fluid between the canyon and the flow above and a uniformly well mixed canyon. However, for the case of a negatively buoyant pollutant, the fluid buoyancy will tend to suppress fluid exchange as additional work is required to lift the dense fluid up and out of the canyon. One would therefore expect that the flushing rate would be a function of the Froude number Fr=U/?g'H as well as the aspect ratio of the canyon H/W. In our experiments the canyon does not remain well mixed, but rather the buoyant fluid is skimmed off the top and the pollutant is etched away over time. We present experimental results for H/W=0.5 and 1 and 0.4

Kaye, Nigel; Hunt, Gary; Syrios, Konstantinos

2008-11-01

25

Buoyant Surface Discharges into Water Bodies. II: Jet Integral Model  

Microsoft Academic Search

The near-field region of a buoyant surface discharge into water bodies often displays significant jet-like motions in form of free jets, shoreline-attached jets, and wall jets, respectively, as classified by the CORMIX3 expert system (see Part I). A new jet integral model CorSurf has been developed that addresses in a single formulation this entire spectrum of jet motions in both

Gerhard H. Jirka

2007-01-01

26

Performance characteristics of a buoyant quad-rotor research aircraft  

NASA Technical Reports Server (NTRS)

Performance characteristics of a buoyant, quadrotor research aircraft, which represents a hybrid airship concept for heavy lift application, are described. Ceiling altitude and endurance for hovering at typical power levels, including partial power failure, are predicted. Climb performance at various altitude and gross weight conditions have been examined. Forward flight performance of this vehicle is illustrated in terms of typical performance parameters such as maximum speed, maximum range, and endurance, over the full range of its payload capability. Optimum payload weights have been identified which result in maximum range at sea level density altitude and constant endurance at various altitudes, both during hover and cruise flights.

Nagabhushan, B. L.; Jacobs, P. P.; Belknap, C. E.; Euler, D. A.

1982-01-01

27

Hands-on experiences with buoyant-less water  

NASA Astrophysics Data System (ADS)

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 tossed bottle filled with water with a small, inflated balloon attached to the bottom by a spring. Practical hints on how to make efficient demonstration experiments are added.

Sliško, Josip; Planinši?, Gorazd

2010-05-01

28

Phytoplankton productivity in a turbid buoyant coastal plume  

NASA Astrophysics Data System (ADS)

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 10 m depending on the age of the plume water. As the plume was 10-15 m 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.

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

29

Neutrally buoyant tracer in gas cleaning equipment: a case study  

NASA Astrophysics Data System (ADS)

A generic problem when studying the gas flow in gas cleaning equipment is that any conventional tracer, whether solid particles or liquid droplets, is separated out in accordance with the purpose of the equipment. This makes it impossible, for instance, to visualize the core of the vortex in centrifugal gas cleaning equipment. This paper explores the use of a neutrally buoyant tracer. The tracer is soap bubbles filled with helium. The smaller density of the helium relative to the surrounding air is precisely compensated by the mass of the bubble film to create a neutrally buoyant tracer. The method is used to study the flow in a swirl-tube gas-solid separator, highlighting flow features that cannot be shown with, for instance, LDA. Results are shown as controlled exposure time photographs, where pathlines of the tracer show the flow pattern. The results are further clarified by high-time-resolution pressure measurements at the walls. The work shows that the vortex core can be directly visualized using this technique. The vortex core is observed to, under some conditions, bend to—and spin around—the wall of the separator. Under other conditions, the vortex core coincides with the separator axis, and extends to the bottom of the hopper under the swirl tube. Also the flow in the downstream tubing is studied. The possibilities for obtaining quantitative data for the gas velocity field are discussed, and a promising method for doing this is identified.

Peng, Weiming; Hoffmann, Alex C.; Dries, Huub W. A.; Regelink, Michiel; Foo, Kee-Khoon

2005-12-01

30

A study of radiation and flow properties of buoyant turbulent diffusion flames  

Microsoft Academic Search

Buoyant pool fires are representative of accidental and arson related fires resulting in extensive property damage and injury to people. Continued research in pool fires is needed to support technology based efforts to reduce fire losses. Motivated by this, a study of radiation and flow characteristics of two laboratory scale buoyant diffusion flames, mimicking pool fire behavior, was undertaken. ^

Kaushik Biswas

2007-01-01

31

Acoustic scattering from a thermally driven buoyant plume revisited John Oeschger  

E-print Network

Acoustic scattering from a thermally driven buoyant plume revisited John Oeschger Coastal Systems and L. Goodman, JASA, Acoustic scattering 1 #12;Far-field weak scattering theory is applied to the case of high frequency broadbandwidth acoustic scattering from a thermally generated buoyant plume

Goodman, Louis

32

Acceleration Statistics of Neutrally Buoyant Spherical Particles in Intense Turbulence  

NASA Astrophysics Data System (ADS)

We measure acceleration statistics of neutrally buoyant spherical particles with a diameter 0.45?, ?a2? decreases with the diameter as d-2/3, in agreement with inertial range scaling arguments. Consistent with earlier work, we find that the scaled acceleration probability density function shows very little dependence on particle size.

Brown, Rachel D.; Warhaft, Z.; Voth, Greg A.

2009-11-01

33

Sheathless hydrodynamic positioning of buoyant drops and bubbles inside microchannels  

NASA Astrophysics Data System (ADS)

Particles, bubbles, and drops carried by a fluid in a confined environment such as a pipe can be subjected to hydrodynamic lift forces, i.e., forces that are perpendicular to the direction of the flow. We investigated the positioning effect of lift forces acting on buoyant drops and bubbles suspended in a carrier fluid and flowing in a horizontal microchannel. We report experiments on drops of water in fluorocarbon liquid, and on bubbles of nitrogen in hydrocarbon liquid and silicone oil, inside microchannels with widths on the order of 0.1-1 mm. Despite their buoyancy, drops and bubbles could travel without contacting with the walls of channels; the most important parameters for reaching this flow regime in our experiments were the viscosity and the velocity of the carrier fluid, and the sizes of drops and bubbles. The dependencies of the transverse position of drops and bubbles on these parameters were investigated. At steady state, the trajectories of drops and bubbles approached the center of the channel for drops and bubbles almost as large as the channel, carried by rapidly flowing viscous liquids; among our experiments, these flow conditions were characterized by larger capillary numbers and smaller Reynolds numbers. Analytical models of lift forces developed for the flow of drops much smaller than the width of the channel failed to predict their transverse position, while computational fluid dynamic simulations of the experiments agreed better with the experimental measurements. The degrees of success of these predictions indicate the importance of confinement on generating strong hydrodynamic lift forces. We conclude that, inside microfluidic channels, it is possible to support and position buoyant drops and bubbles simply by flowing a single-stream (i.e., “sheathless”) carrier liquid that has appropriate velocity and hydrodynamic properties.

Stan, Claudiu A.; Guglielmini, Laura; Ellerbee, Audrey K.; Caviezel, Daniel; Stone, Howard A.; Whitesides, George M.

2011-09-01

34

Buoyant tower being developed for water depths to 10,000 ft  

SciTech Connect

A buoyant tower with a sub-surface wellhead is being developed for oil exploration and production applications. The tower consists of a central stack of cylindrical buoyant chambers connected in a series. Twelve well conductors are positioned around the periphery of the central chamber and run vertically. Installation of the tower is accomplished by a dynamically-positioned crane barge with a buoyant collar. The collar assists in attaching sections of the tower at the surface and lowering the tower to the seabed as it is assembled at the top. The barge is then replaced with a dynamically-positioned drillship, which piles the base to the seafloor and begins drilling.

Not Available

1984-01-01

35

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

Code of Federal Regulations, 2013 CFR

...of a dark color or of a type certified to be resistant to deterioration from ultraviolent light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2013-10-01

36

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

Code of Federal Regulations, 2012 CFR

...of a dark color or of a type certified to be resistant to deterioration from ultraviolent light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2012-10-01

37

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

Code of Federal Regulations, 2011 CFR

...of a dark color or of a type certified to be resistant to deterioration from ultraviolent light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2011-10-01

38

Vehicle concepts and technology requirements for buoyant heavy-lift systems  

NASA Technical Reports Server (NTRS)

Several buoyant-vehicle (airship) concepts proposed for short hauls of heavy payloads are described. Numerous studies identified operating cost and payload capacity advantages relative to existing or proposed heavy-lift helicopters for such vehicles. Applications involving payloads of from 15 tons up to 800 tons were identified. The buoyant quad-rotor concept is discussed in detail, including the history of its development, current estimates of performance and economics, currently perceived technology requirements, and recent research and technology development. It is concluded that the buoyant quad-rotor, and possibly other buoyant vehicle concepts, has the potential of satisfying the market for very heavy vertical lift but that additional research and technology development are necessary. Because of uncertainties in analytical prediction methods and small-scale experimental measurements, there is a strong need for large or full-scale experiments in ground test facilities and, ultimately, with a flight research vehicle.

Ardema, M. D.

1981-01-01

39

AN EXPERIMENTAL/ANALYTICAL INVESTIGATION OF DEEP SUBMERGED MULTIPLE BUOYANT JETS  

EPA Science Inventory

The results of an experimental and analytical study of deep submerged multiple-port thermal discharges are presented. The experimental results include the measured downstream thermal dilution, width, and centerline trajectory of the buoyant thermal plume from multiple port discha...

40

Microstructure and rheology of finite inertia neutrally buoyant suspensions  

E-print Network

The microstructure and rheological properties of suspensions of neutrally buoyant hard spherical particles in Newtonian fluid under conditions of finite inertia are studied using the lattice-Boltzmann method (LBM), which is based on a discrete Boltzmann model for the fluid and Newtonian dynamics for the particles. The suspensions are subjected to simple-shear flow and the properties are studied as a function of Reynolds number and volume fraction, $\\phi$. The inertia is characterized by the particle-scale shear flow Reynolds number $Re = \\frac{\\rho \\dot{\\gamma}a^{2}}{\\mu}$, where $a$ is the particle radius, $\\dot{\\gamma}$ is the shear rate and $\\rho$ and $\\mu$ are the density and viscosity of the fluid, respectively. The influences of inertia and of the volume fraction are studied for $0.005\\leqslant Re \\leqslant 5$ and $0.1\\leqslant \\phi \\leqslant 0.35$. The flow-induced microstructure is studied using the pair distribution function $g(\\boldsymbol{r})$. Different stress mechanisms, including those due to sur...

Haddadi, Hamed

2014-01-01

41

Microstructure and rheology of finite inertia neutrally buoyant suspensions  

E-print Network

The microstructure and rheological properties of suspensions of neutrally buoyant hard spherical particles in Newtonian fluid under conditions of finite inertia are studied using the lattice-Boltzmann method (LBM), which is based on a discrete Boltzmann model for the fluid and Newtonian dynamics for the particles. The suspensions are subjected to simple-shear flow and the properties are studied as a function of Reynolds number and volume fraction, $\\phi$. The inertia is characterized by the particle-scale shear flow Reynolds number $Re = \\frac{\\rho \\dot{\\gamma}a^{2}}{\\mu}$, where $a$ is the particle radius, $\\dot{\\gamma}$ is the shear rate and $\\rho$ and $\\mu$ are the density and viscosity of the fluid, respectively. The influences of inertia and of the volume fraction are studied for $0.005\\leqslant Re \\leqslant 5$ and $0.1\\leqslant \\phi \\leqslant 0.35$. The flow-induced microstructure is studied using the pair distribution function $g(\\boldsymbol{r})$. Different stress mechanisms, including those due to surface tractions (stresslet), acceleration, and the Reynolds stress due to velocity fluctuations are computed and their influence on the first and second normal stress differences, the particle pressure and the viscosity of the suspensions are detailed. The probability density functions of particle force and torque are also presented.

Hamed Haddadi; Jeffrey F. Morris

2014-03-30

42

Buoyant MHD flows in a vertical channel: the levitation regime  

NASA Astrophysics Data System (ADS)

Buoyant magnetohydrodynamic (MHD) flows with Joulean and viscous heating effects are considered in a vertical parallel plate channel. The applied magnetic field is uniform and perpendicular to the plates which are subject to adiabatic and isothermal boundary conditions, respectively. The main issue of the paper is the levitation regime, i.e., the fully developed flow regime for large values of the Hartmann number M, when the hydrodynamic pressure gradient evaluated at the temperature of the adiabatic wall is vanishing. The problem is solved analytically by Taylor series method and the solution is validated numerically. It is found that the fluid velocity points everywhere and for all values of M downward. For small M’s, the velocity field extends nearly symmetrically (with respect to the mid-plane) over the whole section of the channel between the adiabatic and the isothermal walls. For large values of M, by contrast, the fluid levitates over a broad transversal range of the channel, while the motion becomes concentrated in a narrow boundary layer in the neighborhood of the isothermal wall. Accordingly, the fluid temperature is nearly uniform in the levitation range and decreases rapidly within the boundary layer in front of the isothermal wall. It also turns out that not only the volumetric heat generation by the Joule effect, but also that by viscous friction increases rapidly with increasing values of M, the latter effect being even larger than the former one for all M.

Barletta, A.; Celli, M.; Magyari, E.; Zanchini, E.

2008-06-01

43

A numerical study of interacting buoyant cooling-tower plumes  

NASA Astrophysics Data System (ADS)

The compact design of mechanical cooling towers necessitates that the plumes are issued into the cross-wind in close proximity. An improved understanding of the interaction of adjacent plumes is therefore required for better design of such cooling towers, which may lead to a reduction in their environmental impact. This paper presents the results of a numerical investigation into the interaction of two adjacent plumes in a cross-flow. The numerical model simulates small-scale wind tunnel experiments of a cooling tower arrangement. The computations are performed for three-dimensional, turbulent, buoyant and interacting plumes, and for a single plume for comparison. Two double-source arrangements, namely, tandem and side-by-side, with respect to the oncoming atmospheric boundary layer are considered. A low Reynolds number k- ? turbulence model is used with two discretisation schemes, hybrid and QUICK, and the results are compared. Comparisons are also made with the experimental results. The results show that the interaction of side-by-side plumes is dominated by the interaction of the rotating vortex pairs within the plumes. A tandem source arrangement leads to early merging and efficient rise enhancement. Comparisons of the predicted results with experimental data show good agreement for the plume rise.

Bornoff, R. B.; Mokhtarzadeh-Dehghan, M. R.

44

A new Lagrangian method for modelling the buoyant plume rise  

NASA Astrophysics Data System (ADS)

A new method for the buoyant plume rise computation is proposed. Following Alessandrini and Ferrero (Phys A 388:1375-1387, 2009) a scalar transported by the particles and representing the temperature difference between the plume and the environment air is introduced. As a consequence, no more particles than those inside the plume have to be released to simulate the entrainment of the background air temperature. A second scalar, the vertical plume velocity, is assigned to each particle. In this way the entrainment is properly simulated and the plume rise is calculated from the local property of the flow. The model has been tested against data from two laboratory experiments in neutral and stable stratified flows. The comparison shows a good agreement. Then, we tested our new model against literature analytical formulae in a simple uniform neutral atmosphere, considering either the case of a single plume or the one of two plumes from adjacent stacks combining during the rising stage. Finally, a comparison of the model against an atmospheric tracer experiment (Bull Run), characterized by vertically non-homogeneous fields (wind velocity, temperature, velocity standard deviations and time scales), was performed. All the tests confirmed the satisfactory performance of the model.

Alessandrini, Stefano; Ferrero, Enrico; Anfossi, Domenico

2013-10-01

45

Physical and Numerical Modeling of Buoyant Groundwater Plumes  

NASA Astrophysics Data System (ADS)

In coastal states, the injection of treated wastewater into deep saline aquifers offers a disposal alternative to ocean outfalls and discharge directly into local waterways. The density of treated wastewater is similar to that of freshwater but is often much lower than the ambient density of deep aquifers. This significant density contrast can cause upward buoyant movement of the wastewater plume during and after injection. Since some wastewater treatment plants inject more than 100 MGD of this treated wastewater, it is of the utmost importance to be able to not only determine the fate and transport rates of the plume, but to be able to best determine locations for monitoring wells for early detection of possible problems. In this study, both physical and numerical modeling were undertaken to investigate and understand buoyant plume behavior and transport. Physical models using a 2D cross-sectional Plexiglas tank filled with glass beads were carried out under different ambient density scenarios. The experiments consisted of injection of a freshwater pulse-source bubble into a fully saline tank. The injection occurred in an initially static system with no ambient flow. In the scenarios, the freshwater plume migrated vertically upward until reaching the top of the tank. Fingers developed because of the heterogeneity of the density dependent flow field. The vertical velocities and transport patterns of these plumes were compared to one another to investigate variances due to different ambient water densities. Using the finite-difference numerical code SEAWAT to simulate variable density flow, the experiments were numerically modeled and compared with the physical model results. Due to the sensitivity of this problem to numerical resolution, results from three different grids were compared to determine a reasonable compromise between computer runtimes and numerical accuracy. Furthermore, a comparison of advection solvers was undertaken to identify the best solver to use for this specific problem. This involved a comparison between finite- difference, total variation diminishing and mixed Eulerian-Langrangian methods. From these scenarios, the Method of Characteristics (MOC) advection solver with the fine resolution grid (0.1 cm x 0.1 cm x 2.7 cm cells) resulted in a simulation that was in good agreement with the physical experiments. This model was determined to be the base-case problem for further sensitivity analysis. To further verify both the physical and numerical model, SUTRA_MS was also used for comparison. Dimensionless analysis of the flow and transport governing equations was undertaken to determine important physical problem parameters. From these derived dimensionless numbers, it was hypothesized that density, hydraulic conductivity and dispersivity should all play important roles in this problem. A parameter sensitivity analysis was performed using the numerical model base-case. The parameters investigated were hydraulic conductivity, ambient groundwater density, longitudinal dispersivity and injection volume. It was determined that the problem was most sensitive to ambient density, hydraulic conductivity and dispersivity changes as hypothesized, with all three affecting both vertical mass transfer rates, plume fingering and mixing between the fresh and saline waters. The sensitivity to injection volume was not seen to be an important parameter, except for the obvious effect of change in size of the plume.

Brakefield, L. K.; Abarca, E.; Langevin, C. D.; Clement, T. P.

2007-12-01

46

Wave induced transport and mixing of buoyant particles  

NASA Astrophysics Data System (ADS)

The modeling of wave-current and wave-turbulence interactions have received much attention during recent years. Both the breaking of surface waves and the inclusion of the Stokes shear production have been shown to increase the upper ocean turbulence. Furthermore the Coriolis force acting on the Stokes drift redistributes the momentum in the upper ocean, leading to a deflection of the currents. An important application affected by these processes that still needs to be studied is the mixing and drift of particles. Using an ocean column model, 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 effects the drift of suspended particles. Here the suspended particles are buoyant tracers that can represent oil droplets or plankton, for example fish eggs and larvae. 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. Comparing with classical Ekman theory some physical effects on the system are studied, and as a realistic test case we use the model to study the oil drift after an offshore oil spill that took place outside the western coast of Norway in 2007. During this accident the average net drift of oil was observed to be approximately 0.1% of the wind speed at an angle of about 90-120 degrees to the right, far slower and more deflected away from the wind direction than predicted by both numerical and empirical models. With wind and wave forcing from ECMWF reanalysis data, it is shown that the wave effects are important for the resultant drift in this case, and has the potential to improve drift forecasting.

Drivdal, Magnus; Broström, Göran; Christensen, Kai H.

2014-05-01

47

Surface buoyant plumes from melting icebergs in the Labrador Sea  

NASA Astrophysics Data System (ADS)

Canada's Department of Fisheries and Oceans (DFO) conducts annual surveys in the Labrador Sea along the repeat hydrography line AR7W. The occupation of the AR7W line in May 2013 was followed by the experiment aimed at resolving the imprint of melting drifting icebergs on the upper layer thermohaline characteristics in the Labrador Sea. We present high-resolution observations around two icebergs conducted with the towed undulating platform Moving Vessel Profiler (MVP). The first iceberg drifted in relatively warm water of Atlantic origin (~2.5-3.1 °C) off Greenland, while the second iceberg was on the Labrador shelf in cold water below 0 °C. Both icebergs had a lengthscale of O(100 m). In both cases surface buoyant plumes fed by melt water and attached to the iceberg were observed. The plumes were evident in the anomalous thermohaline characteristics of the seawater. Their density anomalies were sufficiently strong to produce visible frontal structures, which imply a development of the intrinsic dynamics associated with a plume. The first plume formed over a time interval of ~10 h, while the second plume formed over several days and extended for more than 1 km (tenfold the iceberg's size). Strong vertical displacements of the pycnocline were observed near the second iceberg. They are interpreted as the internal wave wake. This interpretation is based on the temporal scale of these oscillations (local buoyancy frequency), as well as on the spatial orientation of these waves with respect to the iceberg drift relative to the pycnocline. The observed internal waves partially overlapped with the plume and affected its structure. The saline seawater splashing by swell contributed to the surface melting of the icebergs. Scaling analysis of the second plume suggests that it could be in the “rotational” dynamic regime with recirculating anticyclonic flow.

Yankovsky, Alexander E.; Yashayaev, Igor

2014-09-01

48

Oil-entrapped sterculia gum-alginate buoyant systems of aceclofenac: development and in vitro evaluation.  

PubMed

The current investigation deals with the development and optimization of oil-entrapped sterculia gum-alginate buoyant beads containing aceclofenac by ionotropic emulsion-gelation technique using 3(2) factorial design. The effect of polymer to drug ratio and sodium alginate to sterculia gum ratio on the drug entrapment efficiency (%), and cumulative drug release after 7 h (%) was optimized. The optimized oil-entrapped sterculia gum-alginate buoyant beads containing aceclofenac (F-O) showed drug entrapment efficiency of 90.92±2.34%, cumulative drug release of 41.65±3.97% after 7 h in simulated gastric fluid (pH 1.2), and well buoyancy over 8 h in simulated gastric fluid (pH 1.2) with 5.20 min buoyant lag-time. The in vitro drug release from these buoyant beads followed Korsmeyer-Peppas model (R(2)=0.9866-0.9995) with anomalous (non-Fickian) diffusion drug release mechanism. These new sterculia gum-alginate buoyant beads containing aceclofenac were also characterized using SEM, FTIR, and P-XRD analysis. PMID:23334180

Guru, Pravat Ranjan; Nayak, Amit Kumar; Sahu, Rajendra Kumar

2013-04-01

49

A Lagrangian particle random walk model for simulating a deep-sea hydrothermal plume with both buoyant and non-buoyant features  

NASA Astrophysics Data System (ADS)

This paper presents a computational model of simulating a deep-sea hydrothermal plume based on a Lagrangian particle random walk algorithm. This model achieves the efficient process to calculate a numerical plume developed in a fluid-advected environment with the characteristics such as significant filament intermittency and significant plume meander due to flow variation with both time and location. Especially, this model addresses both non-buoyant and buoyant features of a deep-sea hydrothermal plume in three dimensions, which significantly challenge a strategy for tracing the deep-sea hydrothermal plume and localizing its source. This paper also systematically discusses stochastic initial and boundary conditions that are critical to generate a proper numerical plume. The developed model is a powerful tool to evaluate and optimize strategies for the tracking of a deep-sea hydrothermal plume via an autonomous underwater vehicle (AUV).

Tian, Yu; Li, Wei; Zhang, Ai-qun

2013-04-01

50

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

NASA Technical Reports Server (NTRS)

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.

Browning, R. G. E.

1980-01-01

51

Experiments versus modeling of buoyant drying of porous media  

NASA Astrophysics Data System (ADS)

Experiments versus modeling of buoyant drying of porous media D. Salin and A.G. Yiotis, Laboratoire FAST, Univ Pierre & Marie Curie, Univ. Paris-Sud, CNRS, Orsay 91405, France and E.S. Tajer and Y.C. Yortsos, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1450 A series of isothermal drying experiments in packed glass beads saturated with volatile hydrocarbons (hexane or pentane) are conducted. The transparent glass cells containing the packing allow for the visual monitoring of the phase distribution patterns below the surface, including the formation of liquid films, as the gaseous phase invades the pore space, and for the control of the thickness of the diffusive mass boundary layer over the packing. We demonstrate the existence of an early Constant Rate Period, CRP, that lasts as long as the films saturate the surface of the packing, and of a subsequent Falling Rate Period, FRP, that begins practically after the detachment of the film tips from the external surface. During the CRP, the process is controlled by diffusion within the stagnant gaseous phase in the upper part of the cells, yielding a Stefan tube problem solution. During the FRP, the process is controlled by diffusion within the packing, with a drying rate inversely proportional to the observed position of the film tips in the cell. The critical residual liquid saturation that marks the transition between these two regimes is found to be a function of the average bead size in our packs and the incline of the cells with respect to the flat vertical, with larger beads and angles closer to the vertical position leading to earlier film detachment times and higher critical saturations. We developed a model for the drying of porous media in the presence of gravity. It incorporated effects of corner film flow, internal and external mass transfer and the effect of gravity. Analytical results were derived when gravity opposes drying and hence leads to a stable percolation drying front. We are thus able to obtain results for the drying rates, the critical saturation and the extent of the film region with respect to the various dimensionless numbers that describe the process; the Bond (Bo)number, a film-based Capillary (Ca) number and the dimensionless extent of the mass boundary layer (Sh). The experimental results agree very well with the theory, provided that the latter is generalized to account for the effects of corner roundness in the film region which were neglected in our analytical approach. The agreement is achieved for a specific value of the roundness of the films, which is found to be constant and equal to 0.2 for various conditions, and verify the theoretical dependence on Ca, Bo and Sh numbers.

Salin, D.; Yiotis, A.; Tajer, E.; Yortsos, Y. C.

2012-12-01

52

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

SciTech Connect

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.

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

2012-02-03

53

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

Code of Federal Regulations, 2013 CFR

...be of a dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2013-10-01

54

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

Code of Federal Regulations, 2012 CFR

...be of a dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2012-10-01

55

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

Code of Federal Regulations, 2010 CFR

...be of a dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2010-10-01

56

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

Code of Federal Regulations, 2011 CFR

...be of a dark color or of a type certified to be resistant to deterioration from ultraviolet light; and (3) If metal, be corrosion resistant. (d) If the life float or buoyant apparatus does not have a painter attachment fitting, a...

2011-10-01

57

A buoyant plume adjacent to a headland—Observations of the Elwha River plume  

Microsoft Academic Search

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

Jonathan A. Warrick; Andrew W. Stevens

2011-01-01

58

Buoyant mixing of miscible fluids in tilted tubes T. Son, J.-P. Hulin,a)  

E-print Network

.1063/1.1808771] Gravity induced mixing of miscible fluids in confined vertical or tilted tube geometries is a widespreadBuoyant mixing of miscible fluids in tilted tubes T. Séon, J.-P. Hulin,a) and D. Salin Laboratoire of two fluids in tubes is studied experimentally as a function of the tilt angle from vertical

Hinch, John

59

Buoyant mixing of miscible fluids of varying viscosities in vertical tubes M. Debacq,a)  

E-print Network

; published 5 November 2003 Gravity-induced mixing of two fluids in long vertical tubes is studiedBuoyant mixing of miscible fluids of varying viscosities in vertical tubes M. Debacq,a) J-P. Hulin.2 , the fluid viscosity 1 to 16 10 6 m2 s 1 ) and the tube diameter d 2 to 44 mm . At low density contrasts

Hinch, John

60

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

NASA Technical Reports Server (NTRS)

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.

Kerho, Michael F.

1993-01-01

61

Approximate analysis of the formation of a buoyant solid sphere in a supercooled melt  

Microsoft Academic Search

A mathematical model is presented for the idealized formation and development of a buoyant sphere solidifying in an infinite pool of supercooled liquid. The solid and liquid are of the same pure material and the solid is less dense than the liquid. Initially the liquid is at a uniform temperature that is below its equilibrium freezing temperature, T\\/sub cr\\/, but

A. D. Solomon; D. G. Wilson; V. Alexiades

1986-01-01

62

BUOYANT PLUME DISPERSAL IN THE CONVECTIVE BOUNDARY LAYER: ANALYSIS OF EXPERIMENTAL DATA AND LAGRANGIAN MODELING  

EPA Science Inventory

The aim of this research program is to improve our knowledge and predictive capability of buoyant plume dispersion in the convective boundary layer (CBL) with emphasis on the mean (C) and root-mean-square (?c) concentration fields. The CBL turbulence leads to large random fluc...

63

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

NASA Technical Reports Server (NTRS)

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 earlier tests both at microgravity (using ground-based facilities) and at normal gravity.

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

2000-01-01

64

Potentially buoyant releases at TMI1 (Three Mile Island Unit 1): Source term and steam properties  

Microsoft Academic Search

The Emergency Dose Calculation Model for Three Mile Island-Unit 1 (TMI-1) was recently revised to take into account the guidance of NUREG\\/CR-3354: Potentially Buoyant Releases at Boiling and Pressurized Water Reactors. This guidance was applied to the modeling of radioactive steam releases from the main steam relief valves and atmospheric dump valves at TMI-1. This paper presents an overview of

Ballangee

1989-01-01

65

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

USGS Publications Warehouse

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.

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

2011-01-01

66

A buoyant plume adjacent to a headland—Observations of the Elwha River plume  

NASA Astrophysics Data System (ADS)

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.

Warrick, Jonathan A.; Stevens, Andrew W.

2011-02-01

67

Flickering Behavior of Turbulent Buoyant Fires Using Large-Eddy Simulation  

Microsoft Academic Search

A numerical study investigating the flickering behavior of a turbulent buoyant fire is conducted using large-eddy simulation to examine coupled turbulence, combustion, soot chemistry, and radiation effects. The three-dimensional, Favre-filtered, compressible mass, momentum, energy, and mixture fraction and its scalar variance conservation equations are closed using the Smagorinsky subgrid-scale (SGS) turbulence model. A two-stage predictor-corrector methodology for low-Mach-number compressible flows

S. C. P. Cheung; G. H. Yeoh; A. L. K. Cheung; R. K. K. Yuen; S. M. Lo

2007-01-01

68

Buoyant force and sinking conditions of a hydrophobic thin rod floating on water  

NASA Astrophysics Data System (ADS)

Owing to the superhydrophobicity of their legs, such creatures as water striders and fisher spiders can stand effortlessly, walk and jump quickly on water. Directed toward understanding their superior repellency ability, we consider hydrophobic thin rods of several representative cross sections pressing a water surface. First, the shape function of the meniscus surrounding a circular rod is solved analytically, and thereby the maximal buoyant force is derived as a function of the Young’s contact angle and the rod radius. Then we discuss the critical conditions for a rod to sink into water, including the maximal volume condition and the meniscus-contact condition. Furthermore, we study the sinking conditions and the maximal buoyant forces of hydrophobic long rods with elliptical, triangular, or hexagonal cross-section shapes. The theoretical solutions are quantitatively consistent with existing experimental and numerical results. Finally, the optimized structures of water strider legs are analyzed to elucidate why they can achieve a very big buoyant force on water.

Liu, Jian-Lin; Feng, Xi-Qiao; Wang, Gang-Feng

2007-12-01

69

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

70

Changes in buoyant density and cell size of Escherichia coli in response to osmotic shocks.  

PubMed

The buoyant density of Escherichia coli was shown to be related to the osmolarity of the growth medium. This was true whether the osmolarity was adjusted with either NaCl or sucrose. When cells were grown at one osmolarity and shocked to another osmolarity, their buoyant density adjusted to nearly suit the new osmolarity. When cells were subjected to hyperosmotic shock, they became denser than expected. When cells were subjected to hypoosmotic shock they occasionally undershot the new projected density, but the undershoot was not as dramatic as the overshoot seen with hyperosmotic shocks. Shrinkage and swelling of the cells in response to osmotic shocks could account for the change in their buoyant density. The changes in cell size after osmotic shocks were measured by two independent methods. The first method measured cell size with a Coulter Counter, and the second method measured cell size by stereologic analysis of Nomarski light micrographs. Both methods gave qualitatively similar results and showed the cells to be flexible. The maximum swelling recorded was 23% of the original cell volume, while the maximum shrinkage observed was 33%. PMID:3275627

Baldwin, W W; Sheu, M J; Bankston, P W; Woldringh, C L

1988-01-01

71

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

SciTech Connect

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.

Nelson, Nicholas J.; Toomre, Juri [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0440 (United States); Brown, Benjamin P. [Department of Astronomy and Center for Magnetic Self-Organization (CSMO) in Laboratory and Astrophysical Plasmas, University of Wisconsin, Madison, WI 53706-1582 (United States); Brun, Allan Sacha [Laboratoire AIM Paris-Saclay, CEA/Irfu Universite Paris-Diderot CNRS/INSU, 91191 Gif-sur-Yvette (France); Miesch, Mark S. [High Altitude Observatory, NCAR, Boulder, CO 80307-3000 (United States)

2011-10-01

72

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

73

Buoyant Boats  

NSDL National Science Digital Library

Students conduct a simple experiment to see how the water level changes in a beaker when a lump of clay sinks in the water and when the same lump of clay is shaped into a bowl that floats in the water. They notice that the floating clay displaces more water than the sinking clay does, perhaps a surprising result. Then they determine the mass of water that is displaced when the clay floats in the water. A comparison of this mass to the mass of the clay itself reveals that they are approximately the same.

Engineering K-Phd Program

74

Three-dimensional temperature reconstruction of steady and unsteady buoyant plume by background schlieren technique combined with computed tomography.  

NASA Astrophysics Data System (ADS)

The three-dimensional temperature fields of steady and unsteady buoyant plume issuing into a stagnant surroundings of water are measured by background schlieren technique combined with computed tomography. The measurement system consists of three CCD cameras, inline illuminations system and some optics, which allow three observations of refractive index field of the buoyant plume. The three-dimensional reconstruction technique is applied to the refractive index fields using multiplicative algebraic reconstruction technique for computed tomography. After the confirmation of the reconstruction accuracy with the thermocouple measurement, the experimental technique is applied to the three-dimensional temperature measurement of unsteady buoyant plume. The result reproduces well the unsteady three-dimensional behavior of the plume.

Fujisawa, Nobuyuki; Sato, Gen

2007-11-01

75

Beauty of lotus is more than skin deep: highly buoyant superhydrophobic films.  

PubMed

We develop highly buoyant superhydrophobic films that mimic the three-dimensional structure of lotus leaves. The high buoyancy of these structure stems from mechanically robust bubbles that significantly reduce the density of the superhydrophobic films. These highly buoyant superhydrophobic films stay afloat on water surface while carrying a load that is more than 200 times their own weight. In addition to imparting high buoyancy, the incorporation of robust hydrophilic bubbles enables the formation of free-standing structures that mimic the water-collection properties of Namib Desert beetle. We believe the incorporation of robust bubbles is a general method that opens up numerous possibilities in imparting high buoyancy to different structures that needs to stay afloat on water surfaces and can potentially be used for the fabrication of lightweight materials. (Image on the upper left reproduced with permission from Yong, J.; Yang, Q.; Chen, F.; Zhang, D.; Du, G.; Si, J.; Yun, F.; Hou, X. A Bioinspired Planar Superhydrophobic Microboat. J. Micromech. Microeng. 2014, 24, 035006. Copyright 2014 IOP Publishing.). PMID:24801001

Choi, Yuri; Brugarolas, Teresa; Kang, Sung-Min; Park, Bum Jun; Kim, Byeong-Su; Lee, Chang-Soo; Lee, Daeyeon

2014-05-28

76

Estimating the neutrally buoyant energy density of a Rankine-cycle/fuel-cell underwater propulsion system  

NASA Astrophysics Data System (ADS)

A unique requirement of underwater vehicles' power/energy systems is that they remain neutrally buoyant over the course of a mission. Previous work published in the Journal of Power Sources reported gross as opposed to neutrally-buoyant energy densities of an integrated solid oxide fuel cell/Rankine-cycle based power system based on the exothermic reaction of aluminum with seawater. This paper corrects this shortcoming by presenting a model for estimating system mass and using it to update the key findings of the original paper in the context of the neutral buoyancy requirement. It also presents an expanded sensitivity analysis to illustrate the influence of various design and modeling assumptions. While energy density is very sensitive to turbine efficiency (sensitivity coefficient in excess of 0.60), it is relatively insensitive to all other major design parameters (sensitivity coefficients < 0.15) like compressor efficiency, inlet water temperature, scaling methodology, etc. The neutral buoyancy requirement introduces a significant (?15%) energy density penalty but overall the system still appears to offer factors of five to eight improvements in energy density (i.e., vehicle range/endurance) over present battery-based technologies.

Waters, Daniel F.; Cadou, Christopher P.

2014-02-01

77

Detection of a buoyant coastal wastewater discharge using airborne hyperspectral and infrared imagery  

NASA Astrophysics Data System (ADS)

Municipal wastewater discharged into the ocean through a submerged pipe, or outfall, can rise buoyantly to the sea surface, resulting in a near-field mixing zone and, in the presence of an ambient ocean current, an extended surface plume. In this paper, data from a CASI (Compact Airborne Spectrographic Imager) and an airborne infrared (IR) camera are shown to detect a municipal wastewater discharge off the southeast coast of Florida, U.S.A., through its elevated levels of chromophoric dissolved organic matter plus detrital material (CDOM) and cooler sea surface temperatures. CDOM levels within a ~15-m-diameter surface 'boil' are found to be about twice those in the ambient shelf water, and surface temperatures near the boil are lower by ~0.4°C, comparable to the vertical temperature difference across the ambient water column. The CASI and IR imagery show a nearly identically shaped buoyant plume, consistent with a fully surfacing discharge, but the IR data more accurately delineate the area of most rapid dilution as compared with previous in-situ measurements. The imagery also allows identification of ambient oceanographic processes that affect dispersion and transport in the far field. This includes an alongshore front, which limits offshore dispersion of the discharge, and shoreward-propagating nonlinear internal waves, which may be responsible for an enhanced onshore transport of the discharge.

Marmorino, George O.; Smith, Geoffrey B.; Miller, W. D.; Bowles, Jeffrey H.

2010-01-01

78

Hands-on experiences with buoyant-less water This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Hands-on experiences with buoyant-less water This article has been downloaded from IOPscience.iop.org/journals/physed Hands-on experiences with buoyant-less water Josip Slisko1 and Gorazd Planinsic2 1 Autonomous University we propose two hands-on activities which give students opportunities to infer by themselves

Planin�iè, Gorazd

79

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

NASA Astrophysics Data System (ADS)

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 sequence data. Third, we are working to develop a computational algorithm that can quickly and automatically identify turbulent buoyant jets within video imagery so that autonomous instruments or vehicles can locate and investigate these flows in remote environments without human intervention.

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

2012-12-01

80

Three-Dimensional Upward Flame Spreading in Partial-Gravity Buoyant Flows  

NASA Technical Reports Server (NTRS)

Reduced-gravity environments have been used to establish low-speed, purely forced flows for both opposed- and concurrent-flow flame spread studies. Altenkirch's group obtained spacebased experimental results and developed unsteady, two-dimensional numerical simulations of opposed-flow flame spread including gas-phase radiation, primarily away from the flammability limit for thin fuels, but including observations of thick fuel quenching in quiescent environments. T'ien's group contributed some early flame spreading results for thin fuels both in opposed flow and concurrent flow regimes, with more focus on near-limit conditions. T'ien's group also developed two- and three-dimensional numerical simulations of concurrent-flow flame spread incorporating gas-phase radiative models, including predictions of a radiatively-induced quenching limit reached in very low-speed air flows. Radiative quenching has been subsequently observed in other studies of combustion in very low-speed flows including other flame spread investigations, droplet combustion and homogeneous diffusion flames, and is the subject of several contemporary studies reported in this workshop. Using NASA aircraft flying partial-gravity "parabolic" trajectories, flame spreading in purely buoyant, opposed-flow (downward burning) has been studied. These results indicated increases in flame spread rates and enhanced flammability (lower limiting atmospheric oxygen content) as gravity levels were reduced from normal Earth gravity, and were consistent with earlier data obtained by Altenkirch using a centrifuge. In this work, experimental results and a three-dimensional numerical simulation of upward flame spreading in variable partial-gravity environments were obtained including some effects of reduced pressure and variable sample width. The simulation provides physical insight for interpreting the experimental results and shows the intrinsic 3-D nature of buoyant, upward flame spreading. This study is intended to link the evolving understanding of flame spreading in purely-forced flows to the purely-buoyant flow environment, particularly in the concurrent flow regime; provide additional insight into the existence of steady flame spread in concurrent flows; and stimulate direct comparisons between opposed- and concurrent-flow flame spread. Additionally, this effort is intended to provide direct practical understanding applicable to fire protection planning for the habitable facilities in partial gravity environments of anticipated Lunar and Martian explorations.

Sacksteder, Kurt R.; Feier, Ioan I.; Shih, Hsin-Yi; T'ien, James S.

2001-01-01

81

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

PubMed Central

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

Liu, Jiaping; Wang, Hai; Liu, Qiuhan

2013-01-01

82

A comparison of the quantity and composition of material caught in a neutrally buoyant versus surface-tethered sediment trap  

Microsoft Academic Search

The flux and composition of material caught using two different upper ocean sediment trap designs was compared at the Bermuda Atlantic Time-series Study site (BATS). The standard surface-tethered trap array at BATS was compared to a newly designed neutrally buoyant sediment trap (NBST). Both traps used identical cylindrical collection tubes. Of particular concern was the effect of horizontal flow on

Ken O. Buesseler; Deborah K. Steinberg; Anthony F. Michaels; Rodney J. Johnson; John E. Andrews; James R. Valdes; James F. Price

2000-01-01

83

Evolution of a buoyant outflow in the presence of complex topography: The Dardanelles plume (North Aegean Sea)  

Microsoft Academic Search

The outflow of Waters of Black Sea origin (BSW) through the Dardanelles Strait is the strongest buoyant input for the North Aegean Sea (NAS). Two opposing flows exist across the Dardanelles exit: a lighter, upper layer outflow (BSW) and a denser, deeper layer inflow (waters of Mediterranean origin). This study examines the processes influencing the plume development and evolution. The

Y. S. Androulidakis; V. H. Kourafalou

2011-01-01

84

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

PubMed

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

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

2013-01-01

85

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

USGS Publications Warehouse

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.

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

1993-01-01

86

Experiments on the fragmentation of a buoyant liquid volume in another liquid  

E-print Network

We present experiments on the instability and fragmentation of volumes of heavier liquid released into lighter immiscible liquids. We focus on the regime defined by small Ohnesorge numbers, density ratios of order one, and variable Weber numbers. The observed stages in the fragmentation process include deformation of the released fluid by either Rayleigh-Taylor instability or vortex ring roll-up and destabilization, formation of filamentary structures, capillary instability, and drop formation. At low and intermediate Weber numbers, a wide variety of fragmentation regimes is identified. Those regimes depend on early deformations, which mainly result from a competition between the growth of Rayleigh-Taylor instabilities and the roll-up of a vortex ring. At high Weber numbers, turbulent vortex ring formation is observed. We have adapted the standard theory of turbulent entrainment to buoyant vortex rings with initial momentum. We find consistency between this theory and our experiments, indicating that the conc...

Landeau, Maylis; Olson, Peter

2014-01-01

87

Laminar Smoke Point Based Subgrid Soot Radiation Modeling Applied to LES of Buoyant Turbulent Diffusion Flames  

NASA Astrophysics Data System (ADS)

Large eddy simulations (LES) of gaseous buoyant turbulent flames have been conducted with the application of a flamelet based soot-radiation model. The subgrid model applies a turbulent eddy description of soot formation, oxidation and radiation and is based on the laminar smoke point concept. Two parameters, a local turbulent strain rate and prior enthalpy loss/gain fraction influence the soot formation and radiation. Radiation heat transfer is simulated by solving the finite volume discretized form of the radiative transfer equation (RTE) with the subgrid soot-radiation model implemented. The radiant heating of surfaces in close proximity of the flames is computed and predicted heat fluxes and surface temperatures are compared against experimental data. Fire growth in a rack storage arrangement is simulated with the application of a pyrolysis model. Computed heat release rate (HRR) is compared against experimental data.

Chatterjee, Prateep; de Ris, John L.; Wang, Yi; Krishnamoorthy, Niveditha; Dorofeev, Sergey B.

2012-06-01

88

Dispersal of volcaniclastic material by buoyant water plumes in deep-ocean explosive basaltic eruptions  

NASA Astrophysics Data System (ADS)

The ability of mid-ocean ridge (MOR) volcanic systems to generate explosive eruptions is inhibited by the large hydrostatic pressures associated with their deep-sea location, which suppress volatile exsolution from the magma, and which preclude the generation of steam from lava-water interaction. Nevertheless, volcaniclastic material indicative of explosive activity has been found along many parts of the global MOR, raising important questions regarding the volatile systematics within mid-ocean ridge magmatic systems, and the processes by which volcaniclastic material may be dispersed during deep-sea eruptions. In this study we measured the settling velocities of volcaniclastic grains recovered from the Gakkel Ridge, Loihi Seamount, and Axial Volcano, and developed empirical settling velocity models as a function of particle size for three different particle shapes (angular, sheet, and rod). We then used the Morton, Turner, Taylor turbulent plume model to investigate how a plume of buoyant water may distribute this volcaniclastic material during a deep-sea eruption so that the physical characteristics of the deposits may be used to constrain the location and size (i.e., energy) of the eruptions that produced them. We ran the turbulent plume model for conditions ranging from a typical black smoker (~150 MW) to a megaplume (~30000 MW), and for water column density stratifications and currents corresponding to nominal conditions for the Arctic and Pacific Oceans. We found that maximum dispersal distances for the dominant size of volcaniclastic material within buoyant water plumes range from <100 m for angular clasts, to <1000 m for thin sheets (e.g., limu o Pele). These distances are insufficient to explain the areal extent of the volcaniclastic deposits observed along the 85°E segment of the Gakkel Ridge and various portions of the Juan de Fuca Ridge, indicating that additional energy in the form of momentum from expanding gases is required to produce the observed deposits.

Barreyre, T.; Soule, S.; Reves-Sohn, R. A.

2009-12-01

89

Potentially buoyant releases at TMI1 (Three Mile Island Unit 1): Plume rise and off-site doses  

Microsoft Academic Search

The Emergency Dose Calculation Model for Three Mile Island Unit 1 (TMI-1) was recently revised to take into account the guidance of NUREG\\/CR-3354: Potentially Buoyant Releases at Boiling and Pressurized Water Reactors. The guidance provided was applied to the modeling of radioactive steam releases from the main steam relief valves and atmospheric dump valves at TMI-1. This paper presents an

Heck

1989-01-01

90

On the response of a turbulent coastal buoyant current to wind events: the case of the Western Adriatic Current  

Microsoft Academic Search

This numerical study focuses on the response of the Western Adriatic Current to wind forcing. The turbulent buoyant surface\\u000a current is induced by the Po river outflow in the Adriatic Sea. Idealized and realistic wind conditions are considered by\\u000a retaining the complex geomorphology of the middle Adriatic basin. In the absence of wind, the Adriatic Promontories force\\u000a the current to

Marcello G. Magaldi; Tamay M. Özgökmen; Annalisa Griffa; Michel Rixen

2010-01-01

91

Experimental Study of Buoyant-Thermocapillary Convection in a Rectangular Cavity  

NASA Technical Reports Server (NTRS)

The problem of buoyant-thermocapillary convection in cavities is governed by a relatively large number of nondimensional parameters, and there is consequently a large number of different types of flow that can be found in this system. Previous results give disjoint glimpses of a wide variety of qualitatively and quantitatively different results in widely different parts of parameter space. In this study, we report experiments on the primary and secondary instabilities in a geometry with equal aspect ratios in the range from 1 to 8 in both the direction along and perpendicular to the applied temperature gradient. We thus complement previous work which mostly involved either fluid layers of large extent in both directions, or consisted of investigations of strictly two-dimensional disturbances. We observe the primary transition from an essentially two-dimensional flow to steady three-dimensional longitudinal rolls. The critical Marangoni number is found to depend on the aspect ratios of the system, and varies from 4.6 x 10(exp 5) at aspect ratio 2.0 to 5.5 x 10(exp 4) at aspect ratio 3.5. Further, we have investigated the stability of the three-dimensional flow at larger Marangoni numbers, and find a novel oscillatory flow at critical Marangoni numbers of the order of 6 x 10(exp 5). We suggest possible mechanisms which give rise to the oscillation, and find that it is expected to be a relaxation type oscillation.

Braunsfurth, Manfred G.; Homsy, George M.

1996-01-01

92

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

93

Three-dimensional numerical models of the influence of a buoyant oceanic plateau on subduction zones  

NASA Astrophysics Data System (ADS)

We have investigated potential effects on a subduction zone during oceanic plateau-trench collision, using three-dimensional numerical models. An oceanic plateau of varied density was embedded in the slab, which was pinned at one end. The plateaus strongly influenced the shape of the trench. For a plateau with a higher density, the trench retreat rate was reduced in the region surrounding the plateau, and the plateau subducted along with the slab. For lower density plateaus, the trench in the region of the plateau advanced, and the plateau compressed and resisted subduction, spreading laterally along the trench. With a weaker slab rheology, the arcuate shape of the trench towards the free end of the trench was enhanced. Beneath the most buoyant plateaus, a tear formed in the subducted portion of the slab, soon after the slab tip reached the top of the lower mantle. We compare the model results with a region in the northwest Pacific, where the Ogasawara Plateau meets the trench of the Izu-Bonin-Mariana subduction zone.

Mason, W. G.; Moresi, L.; Betts, P. G.; Miller, M. S.

2010-03-01

94

Experimental Studies for the characterization of the mixing processes in negative buoyant jets  

NASA Astrophysics Data System (ADS)

A negatively buoyant jet (NBJ) corresponds to the physical phenomenon that develops when a fluid is discharged upwards into a lighter environment or downwards into a heavier receptor fluid. In a NBJ the flow is initially driven mostly by the momentum, so it basically behaves as a simple jet released withthe same angle, while far from the outlet the buoyancy prevails, bending the jet axis down and making it similar to a plume. The coexistence in the same phenomenon of both the characteristics of simple jets and plumes makes the NBJs a phenomenon still not entirely explained but, considering also the numerous practical applications, very interesting to study. Here some of the experimental results are presented. The laboratory experiment were obtained on a model simulating a typical sea discharge of brine from desalination plants: a pipe laid down on the sea bottom, with orifices on its lateral wall, releasing brine (heavier than the sea water) with a certain angle to the horizontal, in order to increase the jet path before sinking to the seafloor. A non-intrusive image analysis technique, namely Feature Tracking Velocimetry, is applied to measure velocity fields, with the aim at understanding the influence of some non-dimensional parameters driving the phenomenon (e.g. Reynolds number, release angle) on the structure of the NBJ and of the turbulence.

Besalduch, L. A.; Badas, M. G.; Ferrari, S.; Querzoli, G.

2013-04-01

95

A fast 3D particle method for the simulation of buoyant flow  

NASA Astrophysics Data System (ADS)

This paper describes progress in several areas related to three-dimensional vortex methods and their application to multiphysics problems. The first is the solution of a generic scalar transport equation by advecting and diffusing the scalar gradient along a particle trajectory and onto a mesh, respectively, and recovering the scalar values using a Biot-Savart-like summation. The second is the accurate, high-resolution calculation of the velocity gradient using a fast treecode, which avoids using kinematic relations between the evolution of the gradients and the distortion of the flow map. The same tree structure is used to compute all the variables of interest and those required during the integration of the governing equations. Next, we apply our modified interpolation kernel algorithm for treating diffusion and remeshing to maintain long time accuracy. The coupling between vorticity transport and that of a dynamic scalar, in this case the temperature or density in a gravitational field, is manifested by the generation of vorticity. We demonstrate the performance of the multiphysics algorithm by solving a number of buoyant flow problems.

Schlegel, Fabrice; Wee, Daehyun; Ghoniem, Ahmed F.

2008-11-01

96

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

97

Buoyant flexure and basal crevassing in dynamic mass loss at Helheim Glacier  

NASA Astrophysics Data System (ADS)

Iceberg calving accounts for a significant proportion of annual mass loss from marine-terminating glaciers and may have been a factor in the rapid demise of ancient ice sheets. The largest contributions from the main outlet glaciers of the Greenland ice sheet to sea-level rise over the next two centuries have been projected to be dynamic in origin, that is, driven by glacier flow and calving. However, present physical models remain a coarse approximation of real calving mechanisms because models are poorly constrained by sparse glacier geometry observations. Here we present a record of daily digital elevation models from the calving margin of Greenland’s Helheim Glacier at a high spatial resolution. Our digital elevation models are derived from stereo terrestrial photography taken over the summers of 2010 and 2011. We find that during these two summers dynamic mass loss at Helheim Glacier was dominated by calving events exceeding 1 km3 that were the result of buoyant flexure and the propagation of basal crevasses. We suggest that this buoyancy-driven mechanism for calving may be common elsewhere in Greenland and could be a first-order control on the ice sheet’s future contribution to sea-level rise.

James, Timothy D.; Murray, Tavi; Selmes, Nick; Scharrer, Kilian; O'Leary, Martin

2014-08-01

98

Reexamination of the Association Between Melting Point, Buoyant Density, and Chemical Base Composition of Deoxyribonucleic Acid  

PubMed Central

The equations currently used for the calculation of the chemical base composition of deoxyribonucleic acid (DNA), expressed as moles per cent guanine plus cytosine (% GC), from either buoyant density (?) or midpoint of thermal denaturation (Tm) were recalculated by using only sets of data on DNA determined with the same strains. All available information from the literature was screened and supplemented by unpublished data. The results were calculated by regression and correlation analysis and treated statistically. From the data on 96 strains of bacteria, it was calculated that% GC = 2.44 (Tm – 69.4). Tm appears to be unaffected by the substitution of cytosine by hydroxymethylcytosine. This equation is also valid for nonbacterial DNA. From the data on 84 strains of bacteria, the relation% GC = 1038.47 (–1.6616) was calculated. The constants in this equation are slightly modified when data on nonbacterial DNA are included. Both correlations differ only slightly from those currently used, but now they lean on a statistically sound basis. As a control, the relation between ? and Tm was calculated from data of 197 strains; it agrees excellently with the above two equations. PMID:5438045

De Ley, J.

1970-01-01

99

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

SciTech Connect

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.

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

100

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

PubMed

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

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

2010-12-01

101

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

PubMed Central

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

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

2010-01-01

102

Numerical and experimental modeling of VGF-type buoyant flow under the influence of traveling and rotating magnetic fields  

NASA Astrophysics Data System (ADS)

Numerical and experimental modeling of a VGF-type (VGF—vertical gradient freeze) buoyant flow under the influence of both traveling and rotating magnetic fields (TMF and RMF, respectively) is presented. Low-temperature flow experiments were carried out using a GaInSn alloy as model fluid. Radial heating and cooling of the melt leading to a meridional double vortex flow like in typical VGF growth was introduced using a double-walled melt container. The flow was found to be significantly influenced by the mutual interaction of buoyant and electromagnetically driven forces. With increasing axial temperature difference, the buoyant flow becomes more concentrated in the upper and lower part of the melt leaving an extended melt zone with low flow velocity around the mid-height. Furthermore, VGF-type buoyancy is found to stabilize TMF- and RMF-induced melt flows. Besides, the time evolution of the flow just above the stability threshold is studied. In the case of combined VGF-type/RMF flow complex fluctuation patterns are observed, which depends sensitively on the applied thermal field.

Galindo, V.; Niemietz, K.; Pätzold, O.; Gerbeth, G.

2012-12-01

103

Deformation statistics of sub-Kolmogorov-scale ellipsoidal neutrally buoyant drops in isotropic turbulence  

E-print Network

Small droplets in turbulent flows can undergo highly variable deformations and orientational dynamics. For neutrally buoyant droplets smaller than the Kolmogorov scale, the dominant effects from the surrounding turbulent flow arise through Lagrangian time histories of the velocity gradient tensor. Here we study the evolution of representative droplets using a model that includes rotation and stretching effects from the surrounding fluid, and restoration effects from surface tension including a constant droplet volume constraint, while assuming that the droplets maintain an ellipsoidal shape. The model is combined with Lagrangian time histories of the velocity gradient tensor extracted from DNS of turbulence to obtain simulated droplet evolutions. These are used to characterize the size, shape and orientation statistics of small droplets in turbulence. A critical capillary number, $Ca_c$ is identified associated with unbounded growth of one or two of the droplet's semi-axes. Exploiting analogies with dynamics of polymers in turbulence, the $Ca_c$ number can be predicted based on the large deviation theory for the largest Finite Time Lyapunov exponent. Also, for sub-critical $Ca$ the theory enables predictions of the slope of the power-law tails of droplet size distributions in turbulence. For cases when the viscosities of droplet and outer fluid differ in a way that enables vorticity to decorrelate the shape from the straining directions, the large deviation formalism based on the stretching properties of the velocity gradient tensor loses validity and its predictions fail. Even considering the limitations of the assumed ellipsoidal droplet shape, the results highlight the complex coupling between droplet deformation, orientation and the local fluid velocity gradient tensor to be expected when small viscous drops interact with turbulent flows.

Luca Biferale; Charles Meneveau; Roberto Verzicco

2014-09-02

104

The stability of buoyant bubbles in the atmospheres of galaxy clusters  

E-print Network

The buoyant rise of hot plasma bubbles inflated by AGN outflows in galaxy clusters can heat the cluster gas and thereby compensate radiative energy losses of this material. Numerical simulations of this effect often show the complete disruption of the bubbles followed by the mixing of the bubble material with the surrounding cluster gas due to fluid instabilities on the bubble surface. This prediction is inconsistent with the observations of apparently coherent bubble structures in clusters. We derive a general description in the linear regime of the growth of instabilities on the surface between two fluids under the influence of a gravitational field, viscosity, surface tension provided by a magnetic field and relative motion of the two fluids with respect to each other. We demonstrate that Kelvin-Helmholtz instabilities are always suppressed, if the fluids are viscous. They are also suppressed in the inviscid case for fluids of very different mass densities. We show that the effects of shear viscosity as well as a magnetic fields in the cluster gas can prevent the growth of Rayleigh-Taylor instabilities on relevant scale lengths. R-T instabilities on pc-scales are suppressed even if the kinematic viscosity of the cluster gas is reduced by two orders of magnitude compared to the value given by Spitzer for a fully ionised, unmagnetised gas. Similarly, magnetic fields exceeding a few microG result in an effective surface tension preventing the disruption of bubbles. For more massive clusters, instabilities on the bubble surface grow faster. This may explain the absence of thermal gas in the north-west bubble observed in the Perseus cluster compared to the apparently more disrupted bubbles in the Virgo cluster.

C. R. Kaiser; G. Pavlovski; E. C. D. Pope; H. Fangohr

2005-02-08

105

Ascent and emplacement of buoyant magma bodies in brittle-ductile upper crust  

NASA Astrophysics Data System (ADS)

The emplacement of silicic magma bodies in the upper crust may be controlled by density (such that there is no buoyancy to drive further ascent) or temperature (such that surrounding rocks are too cold to deform significantly over geological timescales). Evidence for the latter control is provided by negative gravity anomalies over many granitic plutons. Conditions of diapir ascent and emplacement in this case are studied with a numerical model for deformation and heat transport allowing for ductile, elastic and brittle behavior. A large-strain formulation is used to solve for temperature, stress, strain, and strain rate fields as a function of time for a range of diapir sizes, density contrasts, and background geotherms. The method allows for large viscosity contrasts of more than 6 orders of magnitude and determines the dominant deformation mechanism depending on the local values of temperature, strain, and strain rate. Emplacement depth and final deformation characteristics depend on diapir size and buoyancy. Small diapirs (less than about 5 km in diameter) cannot reach shallow crustal levels and do not involve brittle deformation. In the ductile regime the diapir flattens significantly upon emplacement due to stiff roof rocks and to the free surface above. Late stage deformation proceeds by horizontal spreading, with little upward displacement of roof rocks and is likely to be interpreted as "ballooning." Large diapirs (more than about 5 km in diameter) rapidly rise to shallow depths (1-5 km) and induce brittle faulting in the overlying rocks. In this regime, buoyancy forces may lead to faulting in roof rocks. In this case, late stage ascent proceeds by vertical intrusion of a plug of smaller horizontal dimensions than the main body. Buoyant diapirs keep on rising after solidification, long after the relatively short-lived high-temperature magmatic stage. This may account for some phases of late caldera resurgence in extinct volcanic systems.

Burov, Evgene; Jaupart, Claude; Guillou-Frottier, Laurent

2003-04-01

106

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

107

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

NASA Technical Reports Server (NTRS)

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.

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

108

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

NASA Astrophysics Data System (ADS)

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 have significant reductions in fuel use and emissions.

Prapas, Jason

109

The motion of a single and multiple neutrally buoyant elliptical cylinders in plane Poiseuille flow  

NASA Astrophysics Data System (ADS)

In this article, we investigate the motion of neutrally buoyant elliptical cylinders in plane Poiseuille flow of a Newtonian fluid. The method of distributed Lagrange multiplier/fictitious domain was used to solve the Navier-Stokes equations as well as for the motion of elliptical cylinders. The motion of a single elliptical cylinder is shown to be dependent on the channel Reynolds number Re, the particle size ratio K = a*/H*, and the aspect ratio A = a*/b* of the cylinder, where H* is the half height of the channel, a* and b* are the lengths of the semi-major axis and semi-minor axis of the cylinder, respectively. It is found that there is a critical Reynolds number, Rec ˜ 3, which distinguishes the lateral migration of a single elliptical cylinder below and above it. As Re is increased, the equilibrium position of the elliptical cylinder shifts towards the wall when Re ? Rec or shifts closer to the central axis when Re ? Rec. Moreover, there are interesting correlations between the center-of-mass trajectories and the orientation dynamics, which depend on the ranges of K and Re. The motion of multiple elliptical cylinders is also affected by the total solid area fraction ?T, which is defined to be the proportion of the area occupied by the cylinders in the domain of computation. For a few elliptical cylinders (the number of cylinders ND = 16 and the corresponding ?T = 3.77%), the cylinders may scatter into several groups at lower Re (? 100), and each group fluctuates about an averaged position. At the higher Re (= 1000), the cylinders may converge to an equilibrium position on each side of the channel center. For a larger number of cylinders (ND = 36, 54, 72, 108, and the corresponding ?T = 8.48%-25.45%), we observed a significant rheological behavior in the velocity profiles. In addition, there exists a particle-free layer next to each wall, and the thickness of the particle-free layers is increased as A (or K) or Re is increased.

Chen, Shih-Di; Pan, Tsorng-Whay; Chang, Chien-Cheng

2012-10-01

110

Buoyant magnetic flux ropes in a magnetized stellar envelope: Idealized numerical 2.5-D MHD simulations  

E-print Network

Context: The context of this paper is buoyant toroidal magnetic flux ropes, which is a part of flux tube dynamo theory and the framework of solar-like magnetic activity. Aims: The aim is to investigate how twisted magnetic flux ropes interact with a simple magnetized stellar model envelope--a magnetic "convection zone"--especially to examine how the twisted magnetic field component of a flux rope interacts with a poloidal magnetic field in the convection zone. Method: Both the flux ropes and the atmosphere are modelled as idealized 2.5-dimensional concepts using high resolution numerical magneto-hydrodynamic (MHD) simulations. Results: It is illustrated that twisted toroidal magnetic flux ropes can interact with a poloidal magnetic field in the atmosphere to cause a change in both the buoyant rise dynamics and the flux rope's geometrical shape. The details of these changes depend primarily on the polarity and strength of the atmospheric field relative to the field strength of the flux rope. It is suggested that the effects could be verified observationally.

S. B. F. Dorch

2006-09-22

111

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

NASA Astrophysics Data System (ADS)

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 ratio of upwelling to shearing rates. A compacting region of reduced porosity develops on the downstream side of a channel. This region advects with the velocity of the matrix. Melt collecting beneath the compacting region generates new tilted melt channels. In the absence of horizontal shear melt rising vertically in the melt channel remains within mantle matrix in the channel. However, horizontal shearing destroys this isolation by causing melt to flow horizontally relative to the matrix. As upwelling rate decreases, and hence the compaction, there is less relative motion between the melt and matrix and the channel behavior agrees more with the theoretical relationship. This behavior may have important geochemical implications for the transport of chemically heterogeneous melts in the deforming mantle. Melt rising in sheared mantle columns may not retain the high pressure signature frequently invoked to explain mid-ocean ridge basalt chemistry if local chemical equilibrium is maintained. [1]. Spiegelman et al. (2001) JGR, 106, 2061-2077. [2]. Schiemenz et al. (2011) Geophys. J. Int. 186, 641-664. [3]. Bangerth et al. (2007) ACM Trans. Math. Software 33, doi: 10.1145/1268776.1268779.

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

2013-12-01

112

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

Microsoft Academic Search

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

John Zinn; Jack Drummond

2005-01-01

113

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

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

2013-10-01

114

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

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

2012-10-01

115

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

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

2013-10-01

116

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

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

2012-10-01

117

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

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

2011-10-01

118

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

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

2011-10-01

119

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

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

2010-10-01

120

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

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

2010-10-01

121

Dynamics of the flammable plumes resulting from the convective dispersion of a fixed mass of the buoyant gaseous fuel, methane, into air  

Microsoft Academic Search

The dynamics of the dispersion of a fixed mass of the buoyant fuel, methane, when exposed with a negligible pressure difference to overlaying air within vertical cylindrical enclosures open to the atmosphere is investigated. Features of the formation and dispersion of flammable mixtures created by the gas dissipation were examined using a 3D CFD model. For the cases considered, the

S. Fardisi; Ghazi A. Karim

2009-01-01

122

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

...Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160...sodium-chloride solution spray at a temperature of 95 °F (35 °C) for...turpentine. (iv) Exposure to a temperature of 0° ±5 °F (?17.6...10 minutes at the ambient temperatures without breaking or...

2012-10-01

123

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

...Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160...sodium-chloride solution spray at a temperature of 95 °F (35 °C) for...turpentine. (iv) Exposure to a temperature of 0° ±5 °F (?17.6...10 minutes at the ambient temperatures without breaking or...

2011-10-01

124

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

...Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160...sodium-chloride solution spray at a temperature of 95 °F (35 °C) for...turpentine. (iv) Exposure to a temperature of 0° ±5 °F (?17.6...10 minutes at the ambient temperatures without breaking or...

2010-10-01

125

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

...Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160...sodium-chloride solution spray at a temperature of 95 °F (35 °C) for...turpentine. (iv) Exposure to a temperature of 0° ±5 °F (?17.6...10 minutes at the ambient temperatures without breaking or...

2013-10-01

126

Relation between shape of liquid-gas interface and evolution of buoyantly unstable three-dimensional chemical fronts  

NASA Astrophysics Data System (ADS)

Buoyantly unstable 3D chemical fronts were seen traveling through an iodate-arsenous acid reaction solution. The experiments were performed in channel reactors with rectangular cross sections, where the top of the reaction solution was in contact with air. A concave or convex meniscus was pinned to reactor lateral walls. Influence of the meniscus shape on front development was investigated. For the concave meniscus, an asymptotic shape of fronts holding negative curvature was observed. On the other hand, fronts propagating in the solution with the convex meniscus kept only positive curvature. Those fronts were also a bit faster than fronts propagating in the solution with the concave meniscus. A relation between the meniscus shape, flow distribution, velocity, and shape is discussed.

Šebestíková, L.

2013-09-01

127

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

PubMed Central

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:24204947

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

128

Formulation and In Vitro evaluation of pH sensitive oil entrapped polymeric blended gellan gum buoyant beads of clarithromycin  

PubMed Central

Background and the purpose of the study A gastroretentive pH sensitive system has been a frontier approach to release the drug in controlled manner in stomach and duodenum. The aim of this study was to develop buoyant beads of gellan based, wherein, the oil was entrapped, blended with hydroxypropyl methyl cellulose or carbopol 934 in order to evaluate its potential for targeted sustained delivery of clarithromycin in the gastric region. Methods Buoyant beads of gellan was developed by inotropic gelation technique using calcium carbonate as gas forming agent and the drug polymer dispersion was emulsified with mineral oil. The oil was entrapped and blended with hydroxypropyl methyl cellulose or carbopol 934. The developed beads were evaluated in terms of diameter,% floating, encapsulation efficiency, In vitro drug release, In vivo gastric residence efficacy and clarithromycine concentration in the mucosa of the experimental animal model. Results The scanning electron microscope photograph indicated that the prepared beads were spherical in shape and buoyancy, encapsulation efficiency and drug content obtained from all batches were satisfactory. Particle size and percentage buoyancy of the gel beads increased by raising the concentration of calcium carbonate. The formulation exhibited sustained release profile and was best fitted in the Peppas model with n<0.45. Subsequent coating of microbeads exhibited zero-order sustained pattern of the drug release up to 8 hrs. Batch B4 showed comparatively better residence and the drug concentration in the gastric mucosa of the treated animals. Conclusion The result provides evidence that the prepared optimized formulation may be used effectively for pH sensitive gastric targeted antibiotic such as clarithromycin. PMID:22615623

Tripathi, G.; Singh, S.

2010-01-01

129

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

PubMed

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:24204947

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

130

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

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.

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

1997-01-01

131

Modeling possible spreadings of a buoyant surface plume with lagrangian and eulerian approaches at different resolutions using flow syntheses from 1992-2007 - a Gulf of Mexico study  

Microsoft Academic Search

We present results from an ensemble of BP oil spill simulations. The oil spill slick is modeled as a buoyant surface plume that is transported by ocean currents modulated, in some experiments, by surface winds. Ocean currents are taken from ECCO2 project (see http:\\/\\/ecco2.org ) observationally constrained state estimates spanning 1992-2007. In this work we (i) explore the role of

R. Tulloch; C. N. Hill; O. Jahn

2010-01-01

132

Effect of Chemical Kinetics on Concurrent-Flow Flame Spread over Solids: A Comparison Between Buoyant Flow and Forced Flow Cases  

Microsoft Academic Search

The authors employed detailed numerical models with a one-step finite-rate chemical reaction to investigate the kinetic rate effect (through the variation of the pre-exponential factor) on concurrent flame spread rates over thin solids. It is found that flames in forced flow are less sensitive to the change of kinetics than flames in buoyant flow, and narrow samples are more sensitive

Sheng-Yen Hsu; James S. Tien

2011-01-01

133

In-Situ Optical and Acoustical Measurements of the Buoyant Cyanobacterium P. Rubescens: Spatial and Temporal Distribution Patterns  

PubMed Central

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. PMID:24303028

Hofmann, Hilmar; Peeters, Frank

2013-01-01

134

Microgravity Experiments and Numerical Modeling of Rotating Buoyant Convection in a Spherical Shell with Latitudinal Thermal Gradients  

NASA Technical Reports Server (NTRS)

The results of numerical model calculations are compared with space laboratory experiments for rotating, thermally driven flow in a hemispherical shell, and various flow regimes are described. A spherically symmetric body force, analogous to gravity, is imposed in the radial direction through the use of a dielectric fluid and an electrostatic potential difference across the gap. The spherical boundaries are maintained at constant temperature profiles (with the pole and the inner sphere being the warmer surfaces), and the equatorial wall is an insulator. Typical parameter combinations result in highly nonlinear, but laminar, flow. For weak enough buoyant forcing, the flow is axisymmetric. It consists of a single meridional cell, rising in warm latitudes (in this case, near the pole) and sinking in cool latitudes, with prograde flow in the equatorial region and near the inner hemisphere for other latitudes, and retrograde motion elsewhere. For fast rotation, the first transition due to the instability of this simple flow is also axisymmetric, consisting of rings of convection in the polar region, which propagate poleward. The first nonaxisymmetric convection occurs at Rayleigh numbers which increase with rotation rate. The form of the convection near the transition also depends upon the rate of rotation. Selected flow patterns near the transition as well as those beyond it are studied numerically. For those cases where there exist laboratory experiments with which to compare, the numerical and experimental results agree very well.

Leslie, Fred W.; Miller, Timothy L.

1998-01-01

135

Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust  

NASA Astrophysics Data System (ADS)

the causes of rock and surface uplift is important because they control the location of mountain building, depocenters, and drainage characteristics and can influence climate. Here we combine previous thermochronological data with field observations to determine the amount of exhumation, rock, and surface uplift that occurs in the upper plate of Central and South American subduction zones during the collision, accretion, and subduction of oceanic plateaus and aseismic ridges. The collision of buoyant and topographically prominent oceanic plateaus and ridges can drive at least 5 km of rock uplift within 2 Ma. Uplift appears to be an immediate response to collision and is generally independent of the slab dip. The amount of rock uplift is controlled mainly by excess topography associated with the ridge (ultimately linked to buoyancy) and erosion, while it is also influenced by the strength of the subduction interface related to the presence of volcanic asperities and overpressured sediments in the subduction channel. The quantity of exhumation is strongly dependant on climate-induced erosion and the lifespan over which the topography is uplifted and supported. Sediment draining into the trench may leave the elevated ridge axis sediment starved, increasing the shear stresses at the ridge subduction interface, leading to positive feedback between ridge subduction, rock uplift, and exhumation. Trench-parallel variations in exhumation have a direct impact on exploration paradigms for porphyry-related metalliferous deposits, and it is likely that porphyry systems are completely eroded by the impingement of plateaus and aseismic ridges within temperate and tropical climates.

Spikings, Richard; Simpson, Guy

2014-05-01

136

Evolution of a buoyant outflow in the presence of complex topography: The Dardanelles plume (North Aegean Sea)  

NASA Astrophysics Data System (ADS)

The outflow of Waters of Black Sea origin (BSW) through the Dardanelles Strait is the strongest buoyant input for the North Aegean Sea (NAS). Two opposing flows exist across the Dardanelles exit: a lighter, upper layer outflow (BSW) and a denser, deeper layer inflow (waters of Mediterranean origin). This study examines the processes influencing the plume development and evolution. The complex topography of the receiving basin (NAS) plays a significant role on the preferred BSW pathways that are controlled by the buoyancy and wind forcing. A high-resolution numerical model, the NAS-HYCOM (Hybrid Coordinate Ocean Model), is implemented to perform process-oriented experiments that examine the relative role of the forcing factors and topographic effects. Three major pathways are identified. In the absence of wind, an anticyclonic bulge is formed inducing a Westward Jet that is topographically guided between two islands near the outflow. Topography also controls the development of a buoyancy-driven Coastal Current and a Rim Current along the North Aegean shelf areas. Comparison of model results to analytical calculations suggests that topography modifies the formation and the ballooning of the anticyclonic bulge, which are controlled by the outflow rate, the resulting stratification and Coriolis. Experiments also employ several wind directions and magnitudes in combination with different outflow characteristics. The study elucidates the importance of the Aegean morphology on the processes controlling the coupling to the Black Sea. The BSW are found to influence both deep and shelf Aegean basins, along their overall cyclonic pathway toward the eastern Mediterranean.

Androulidakis, Y. S.; Kourafalou, V. H.

2011-04-01

137

The relative importance of local retention and inter-reef dispersal of neutrally buoyant material on coral reefs  

NASA Astrophysics Data System (ADS)

Reef-scale, eddy-resolving numerical models are applied to discriminate between local trapping of neutrally buoyant passive material coming from a natal reef versus trapping of this material on reefs downstream. A hydrodynamic model is coupled with a Lagrangian (nongridded) dispersal simulation to map the movement of material such as passive larvae within and between natural reefs. To simplify the interpretation, a number of schematic reef shapes, sizes and spacings were devised to represent the most common cases typifying Australia's Great Barrier Reef. Prior investigations have shown that coral reefs on the Great Barrier Reef may retain material for times equivalent to the pelagic dispersal period of many species. This paper explores whether larvae are more likely to settle on the natal reef, settle downstream or fail to settle at all. The modelling neglects active larval behaviour and treats the vertically well-mixed case of notionally weightless particles only. The crown-of-thorns starfish larvae with a pelagic dispersal period of at least 10 days are one example of this case. Larvae are most likely to be found near the natal reef rather than its downstream neighbour, mostly because the currents take the vertically well-mixed material around, rather than onto, the downstream reef. Of all the simulations, the highest numbers were found on natal reefs (e.g. 8% after 10 days) while downstream numbers mostly varied between 0 and 1% after 10 days. Particle numbers equalised only when spacing between the two reefs was less than the reef length (6 km), or when the downstream reef was in the direct path of the larval stream.

Black, Kerry P.

1993-03-01

138

Ethyl cellulose and hydroxypropyl methyl cellulose buoyant microspheres of metoprolol succinate: Influence of pH modifiers  

PubMed Central

Introduction: Incorporation of pH modifier has been the usual strategy employed to enhance the dissolution of weakly basic drug from floating microspheres. Microspheres prepared using a combination of both ethyl cellulose (EC) and hydroxypropyl methylcellulose (HPMC) which shows highest release were utilize to investigate the effect of fumaric acid (FA), citric acid (CA), ascorbic acid (AA) and tartaric acid (TA) (all 5-20% w/w) incorporation on metoprolol succinate (MS) release. Materials and Methods: EC, HPMC alone or in combination were used to prepare microspheres that floated in simulated gastric fluid and evaluated for a percent yield, drug entrapment, percent buoyancy and drug release. The higher drug release in combination (MS:HPMC:EC, 1:1:2) was selected for the evaluation of influence of pH modifiers on MS release. CA (5-20% w/w), AA (5-20% w/w), FA (5-20% w/w) and TA (5-20% w/w) were added and evaluated for drug release. Present investigation is directed to develop floating drug delivery system of MS by solvent evaporation technique. Results: The microspheres of MS:HPMC:EC (1:1:2) exhibited the highest entrapment (74.36 ± 2.18). The best percentage yield was obtained at MS:HPMC (1:1) (83.96 ± 1.50) and combination of MS:HPMC:EC (1:1:2) (79.23 ± 1.63). Conclusion: MS release from the prepared microspheres was influenced by changing MS-polymer, MS-polymer-polymer ratio and pH modifier. Although significant increment in MS release was observed with CA (20% w/w), TA (20% w/w) and AA (20% w/w), addition of 20% w/w FA demonstrated more pronounced and significant increase in drug entrapment as well as release from MS:HPMC:EC (1:1:2) buoyant microspheres. PMID:24167789

Raut, Neha S; Somvanshi, Sachin; Jumde, Amol B; Khandelwal, Harsha M; Umekar, Milind J; Kotagale, Nandkishor Ramdas

2013-01-01

139

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

NASA Astrophysics Data System (ADS)

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 (

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

2012-11-01

140

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)

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.

Havill, C. D.

1974-01-01

141

Near-field mixing of a vertical buoyant jet in a shallow crossflow: Implications on adsorption and flocculation  

NASA Astrophysics Data System (ADS)

The behaviour and movement of pulpmill pollutants discharged into the Northern Fraser River is of significant concern due to their potential impact on this valuable aquatic ecosystem. The shallow receiving water can influence the mixing and subsequent dilution of these discharges. The association of contaminants with suspended sediment, either by direct adsorption or flocculation of contaminated solids discharged with the effluent (biosolids), also affects pollutant fate. This study examined the effects of a shallow crossflow in the near field mixing of a vertical buoyant jet, specifically dilution and trajectory. Physical mixing experiments were carried out in a shallow ambient current over a range of conditions similar to those seen in the Fraser River, specifically peak and low flow conditions. The dilution and trajectory results were then compared to those predicted by CORMIX1. The mechanism of association of contaminants with suspended sediment under these near field conditions was also investigated. A jet classification scheme was developed based on the behaviour of the jets in the shallow crossflow. Jets were classified to be Bottom, Intermediate or Surface Jets. Bottom Jets were influenced primarily by interaction of the jet with the bottom boundary layer, resulting in significantly higher levels of dilution and possible bottom attachment. The mixing of Intermediate Jets was more complicated due to interaction with both the top and bottom boundaries: the free surface inhibited mixing while interactions with the boundary layer enhanced mixing. Surface Jets were drastically affected by the free surface, with a reduction in dilution due to impingement on the free surface. The CORMIX1 model was found to be unsuitable for predicting the dilution in this application since it does not consider the effects of either the free surface or the bottom boundary layer on jet mixing. Adsorption was found to play a limited role in the near field region. Of greater importance, is the potential for flocculation of biosolids with suspended sediment. The most important parameter in predicting where the conditions for this increased flocculation will occur was the ratio of the number of biosolid, particles to the number of suspended sediment particles.

Gomm, Leslie Sharon

1999-10-01

142

JBFA - buoyant flight  

NASA Technical Reports Server (NTRS)

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.

Ohari, T.

1982-01-01

143

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

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.

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

1997-01-01

144

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

SciTech Connect

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.

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

1993-10-01

145

The potential for buoyant displacement gas release events in Tank 241-SY-102 after waste transfer from Tank 241-SY-101  

SciTech Connect

Tank 241-SY-101 (SY-101) is a double-shell, radioactive waste storage tank with waste that, before the recent transfer and water back-dilution operations, was capable of retaining gas and producing buoyant displacement (BD) gas release events (GREs). Some BD GREs caused gas concentrations in the tank headspace to exceed the lower flammability limit (LFL). A BD GRE occurs when a portion of the nonconvective layer retains enough gas to become buoyant, rises to the waste surface, breaks up, and releases some of its stored gas. The installation of a mixer pump in 1993 successfully mitigated gas retention in the settled solids layer in SY-101 and has since prevented BD GREs. However, operation of the mixer pump over the years caused gas retention in the floating crust layer and a corresponding accelerated waste level growth. The accelerating crust growth trend observed in 1997--98 led to initiation of sequences of waste removal and water back-dilutions in December 1999. Waste is removed from the mixed slurry layer in Tank SY-101 and transferred into Tank 241-Sy-102 (SY-102). Water is then added back to dissolve soluble solids that retain gas. The initial transfer of 89,500 gallons of SY-101 waste, diluted in-line at 0.94:1 by volume with water, to SY-102 was conducted in December 1999. The second transfer of 230,000 gallons of original SY-101 waste, diluted approximately 0.9:1, was completed in January 2000, and the third transfer of 205,500 gallons of original SY-101 waste diluted at 0.9:1 was completed in March 2000.

BE Wells; PE Meyer; G Chen

2000-05-10

146

Modeling possible spreadings of a buoyant surface plume with lagrangian and eulerian approaches at different resolutions using flow syntheses from 1992-2007 - a Gulf of Mexico study  

NASA Astrophysics Data System (ADS)

We present results from an ensemble of BP oil spill simulations. The oil spill slick is modeled as a buoyant surface plume that is transported by ocean currents modulated, in some experiments, by surface winds. Ocean currents are taken from ECCO2 project (see http://ecco2.org ) observationally constrained state estimates spanning 1992-2007. In this work we (i) explore the role of increased resolution of ocean eddies, (ii) compare inferences from particle based, lagrangian, approaches with eulerian, field based, approaches and (ii) examine the impact of differential response of oil particles and water to normal and extreme, hurricane derived, wind stress. We focus on three main questions. Is the simulated response to an oil spill markedly different for different years, depending on ocean circulation and wind forcing? Does the simulated response depend heavily on resolution and are lagrangian and eulerian estimates comparable? We start from two regional configurations of the MIT General Circulation Model (MITgcm - see http://mitgcm.org ) at 16km and 4km resolutions respectively, both covering the Gulf of Mexico and western North Atlantic regions. The simulations are driven at open boundaries with momentum and hydrographic fields from ECCO2 observationally constrained global circulation estimates. The time dependent surface flow fields from these simulations are used to transport a dye that can optionally decay over time (approximating biological breakdown) and to transport lagrangian particles. Using these experiments we examine the robustness of conclusions regarding the fate of a buoyant slick, injected at a single point. In conclusion we discuss how future drilling operations could use similar approaches to better anticipate outcomes of accidents both in this region and elsewhere.

Tulloch, R.; Hill, C. N.; Jahn, O.

2010-12-01

147

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)

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.

toberman, matthew; Inall, Mark; Boyd, Tim

2013-04-01

148

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

PubMed Central

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

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

1985-01-01

149

Hydrodynamic interaction of two neutrally-buoyant smooth spheres suspended in plane Poiseuille flow: the BEM simulations versus the MoR approximations  

NASA Astrophysics Data System (ADS)

The hydrodynamic interaction between two particles suspended in shear flows is fundamental to the macroscopic characterization of suspension flows. Although such interaction in quiescent or linear shear flow is well understood, studies on that in a nonlinear shear field are rare. In this study, the hydrodynamic interaction between two neutrally-buoyant smooth spheres moving at negligible Reynolds numbers in an unbounded plane Poiseuille flow has been calculated by three-dimensional boundary element method (BEM) simulations. The BEM results have been compared with the analytical results obtained with the method-of-reflection (MoR) approximations. The BEM simulations have been found to provide satisfactory predictions if the number of elements on the spheres are more than 200, whereas the MoR approximations provide satisfactory predictions only when the minimum separation between the spheres is relatively large although this MoR method has the advantage to easily calculate the hydrodynamic interaction between two spheres freely moving at negligible Reynolds numbers in unbounded quadratic flow by solving ordinary differential equations. Furthermore, it is found that there is a preferential cross-streamline migration of the center-of-gravity of the sphere-pair in the plane of shear in plane Poiseuille flow which does not arise in simple shear flow. This migration is always directed towards low shear regions when the sphere having larger translational velocity approaches the other sphere, and reverses towards high shear regions when the faster sphere leads the other sphere in the plane of shear. There is also a cross-streamline migration of the center-of-gravity of the sphere-pair in the plane of vorticity, but this migration does not have a preferential direction. These migrations are symmetric about the point where the spheres are at the minimum separation, and are only significant when the hydrodynamic interaction of the spheres is strong. These results show that the migration of the center-of-gravity of the sphere-pair can be attributed to the nonlinearity of the shear field, which agrees with the MoR approximations. The hydrodynamic interaction between the two spheres has been quantified under various conditions by the BEM simulations for both identical and disparate spheres.

Lin, W.; Graham, A. L.; Ingber, M. S.; Abbott, J. R.; Leggoe, J. W.

2005-09-01

150

ANALYSIS OF BUOYANT SURFACE JETS  

EPA Science Inventory

To obtain improved prediction of heated plume characteristics from a surface jet, an integral analysis computer model was modified and a comprehensive set of field and laboratory data available from the literature was gathered, analyzed, and correlated for estimating the magnitud...

151

Mitochondrial and cytoplasmic ribosomes from mammalian tissues. Further characterization of ribosomal subunits and validity of buoyant-density methods for determination of the chemical composition and partial specific volume of ribonucleoprotein particles  

PubMed Central

1. At 0–4°C mitochondrial ribosomes (55S) dissociate into 39S and 29S subunits after exposure to 300mm-K+ in the presence of 3.0mm-Mg2+. When these subunits are placed in a medium containing a lower concentration of K+ ions (25mm), approx. 75% of the subparticles recombine giving 55S monomers. 2. After negative staining the large subunits (20.3nm width) usually show a roundish profile, whereas the small subunits (12nm width) show an elongated, often bipartite, profile. The dimensions of the 55S ribosomes are 25.5nm×20.0nm×21.0nm, indicating a volume ratio of mitochondrial to cytosol ribosomes of 1:1.5. 3. The 39S and 29S subunits obtained in high-salt media at 0–4°C have a buoyant density of 1.45g/cm3; from the rRNA content calculated from buoyant density and from the rRNA molecular weights it is confirmed that the two subparticles have weights of 2.0×106 daltons and 1.20×106 daltons; the weights of the two subunits of cytosol ribosomes are 2.67×106 and 1.30×106 daltons. 4. The validity of the isodensity-equilibrium-centrifugation methods used to calculate the chemical composition of ribosomes was reinvestigated; it is confirmed that (a) reaction of ribosomal subunits with 6.0% (v/v) formaldehyde at 0°C is sufficient to fix the particles, so that they remain essentially stable after exposure to dodecyl sulphate or centrifugation in CsCl, and (b) the partial specific volume of ribosomal subunits is a simple additive function of the partial specific volumes of RNA and protein. The RNA content is linearly related to buoyant density by the equation RNA (% by wt.)=349.5?(471.2×1/?CsCl), where 1/?CsCl=[unk]RNP (partial specific volume of ribonucleoprotein). 5. The nucleotide compositions of the two subunit rRNA species of mitochondrial ribosomes from rodents (42% and 43% G+C) are distinctly different from those of cytoplasmic ribosomes. ImagesPLATE 1PLATE 2 PMID:563718

Sacchi, Ada; Ferrini, Ugo; Londei, Paola; Cammarano, Piero; Maraldi, Nadir

1977-01-01

152

Experimental investigation of a stratified buoyant wake  

E-print Network

Hz signals 180? out of phase with respect to each other. These two 15 Hz signals are then used to trigger the flash lamp of the respective lasers. Details of the setup and operation of the triggering system are included in Appendix A... Hz signals 180? out of phase with respect to each other. These two 15 Hz signals are then used to trigger the flash lamp of the respective lasers. Details of the setup and operation of the triggering system are included in Appendix A...

Kraft, Wayne Neal

2004-11-15

153

Buoyant currents arrested by convective dissolution  

E-print Network

When carbon dioxide (CO[subscript 2]) dissolves into water, the density of water increases. This seemingly insubstantial phenomenon has profound implications for geologic carbon sequestration. Here we show, by means of ...

MacMinn, Christopher W.

154

TURBULENCE MODELING APPLIED TO BUOYANT PLUMES  

EPA Science Inventory

A viable computer model was developed that is based on second-order closure of the turbulent correlation equations for predicting the fate of nonchemically reacting contaminants released in the atmospheric boundary layer. The invariant turbulence model discussed in previous repor...

155

JBFA-Buoyant Flight, Special Edition  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

156

Science NetLinks: Buoyant Boats  

NSDL National Science Digital Library

This lessson plan for grades 3-5 has students design and construct boats to test their buoyancy. The lesson is designed to help students understand both buoyancy and Archimedes Principle. Included is a printable student activity for testing and comparing the buoyancy of boats. This is part of a larger collection of lessons, all of which are aligned with specific AAAS Benchmarks for Scientific Literacy.

Science, American A.

2008-08-15

157

A buoyant life investigating mobile platform (BLIMP)  

NASA Astrophysics Data System (ADS)

The search for life in new environments, e.g., Mars/Titan, will be scientifically challenging and have great engineering difficulties. In this paper the authors discuss an approach to field-testing methods relevant to three scientific thrusts in the detection of life and pre-biotic organics on other worlds. We describe how this can be accomplished through a series of field trials using a mobile aerial vehicle that is a proxy for the exploration approaches and instrument techniques necessary for the next stage of life detection on other planets. We do this by deploying a mobile organic laboratory on Earth to demonstrate the requisite techniques. We show how terrestrial field trials provide new insights on the colonization by life of fresh volcanic flows, and the competition between biotic and abiotic processes on a newly cooling piece of the Earth’s crust. This paper suggests that such work could be very effectively conducted on Hawaii, where the erupted lava is basaltic, an important crustal component for terrestrial planets. The presence of water is generally agreed to be a prerequisite for planetary habitability but the combination of basalt and water is chemically unstable at the temperatures to which basalt cools after eruption. The subsequent chemical reactions occur because the total energy of the products is lower than that of the precursor materials and on Earth biological processes result from organisms harvesting that difference in energy. For life processes to succeed they must out-compete the rate at which abiotic chemistry might accomplish the same tasks. Monitoring the rate at which chemical processes occur is therefore a life-detection approach. Biotic involvement in the rate of weathering of basalts is the test case for this new, generic life detection paradigm. This approach would be applicable to the periglacial zones of Mars, if liquid water were proven to be present there. We show that a 15 m autonomous BLIMP could carry various instrument packages including camera, visible spectrometer, tunable diode laser spectrometer (TDLS) for gas and gas isotope analysis, gas chromatograph/mass spectrometer (GCMS). These could be calibrated followed by ground-truthing using field experiments in the interior of Meteor Crater in Arizona. This well understood system could then study the extreme environment of the still active volcanic caldera of Kilauea and the adjacent older lava flows. For Mars the BLIMP is a proxy for a lighter balloon or even a Martian Rover, which could carry a similar suite of instruments and take a similar set of measurements. For Titan, with its dense and high-molecular weight atmosphere calm winds and low gravity, a BLIMP will be the vehicle of choice. The experiments would be directly relevant. We discuss how a Titan BLIMP could search for organic compounds in the post-Cassini exploration of Titan.

Coleman, Max; Rodgers, David; Jones, Jack

2006-01-01

158

A New Tanarctid Arthrotardigrade with Buoyant Bodies  

Microsoft Academic Search

Four cruises have revealed a very rich tardigrade fauna inhabiting the shell gravel at the Faroe Bank and Bill Bailey Bank in the North Atlantic. This study presents the description of Tanarctus bubulubus sp. n., which is one of the many new tanarctids from the Faroe Bank. The new species is found from 104 m to 200 m and is

Aslak Jörgensen; Reinhardt Møbjerg Kristensen

2001-01-01

159

A Simple buoyant craft for autonomous exploration  

NASA Astrophysics Data System (ADS)

A simple, autonomous, floating craft is described that was designed to take digital images of approximately 1 m2 areas of the ground in rocky terrain. The vehicle (Monty) consisted of a helium-filled balloon and rolling framework that successfully traversed a wide variety of features, including steep rocky slopes with boulders >1 m in diameter and at wind speeds as high as 5 m/ s at the Haughton Impact Crater in the Canadian Arctic. This vehicle concept has obvious implications for the exploration of other planetary bodies that have an atmosphere.

Stokes, M. Dale

160

A Buoyant Life Investigating Mobile Platform (BLIMP)  

NASA Astrophysics Data System (ADS)

The Search for Life in new environments, e.g. Mars/Titan, will be scientifically challenging and have great engineering difficulties. In this paper we discuss an approach to field-testing methods relevant to three scientific thrusts in the detection of life and pre-biotic organic compounds on other worlds. We describe how this can be accomplished through a series of field trials using a mobile aerial vehicle that is a proxy for the exploration approaches and instrument techniques necessary for the next stage of life detection on other planets. We do this by deploying a mobile organic laboratory on Earth to demonstrate the requisite techniques. Terrestrial field trials will provide new insights on the colonization by life of fresh volcanic flows, and the competition between biotic and abiotic processes on a newly cooling piece of the Earth's crust. This paper suggests that such work could be very effectively conducted on Hawaii, where the erupted lava is basaltic, an important crustal component for terrestrial planets. The presence of water is generally agreed to be a prerequisite for planetary habitability but the combination of basalt and water is chemically unstable at the temperatures to which basalt cools after eruption. The subsequent chemical reactions occur because the total energy of the products is lower than that of the precursor materials and on Earth biological processes prosper by harvesting that difference in energy. For life processes to succeed they must out-compete the rate at which abiotic chemistry might accomplish the same tasks. Monitoring the rate at which chemical processes occur is therefore a life-detection approach. Biotic involvement in the rate of weathering of basalts is a test case for this new, generic life detection paradigm. This approach would be applicable to the periglacial zones of Mars, if liquid water were proven to be present there. We show that the use of a 15 meter autonomous blimp to carry various instrument packages (including camera, visible spectrometer, Tunable Diode Laser Spectrometer (TDLS) for gas and gas isotope analysis, gas chromatograph/mass spectrometer (GCMS). These could be calibrated followed by ground-truthing using field experiments in the interior of Meteor Crater in Arizona. This well understood system could then study the extreme environment of the still active volcanic caldera of Kilauea and the adjacent older lava flows. For Mars the blimp is a proxy for a lighter balloon or even a Martian Rover, which could carry a similar suite of instruments and take a similar set of measurements. For Titan, with its dense and high-molecular weight atmosphere calm winds and low gravity, a blimp will be the vehicle of choice. The experiments would be directly relevant. We discuss how a Titan Blimp could search for organic compounds in the post-Cassini exploration of Titan.

Coleman, M.; Jones, J.; Rodgers, D.

161

Candle Flames in Non-Buoyant Atmospheres  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

162

Candle Flames in Non-Buoyant Atmospheres  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

163

Candle Flames in Non-Buoyant Atmospheres  

Microsoft Academic Search

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

D. L. DIETRICH; H. D. ROSS; Y. SHU; P. CHANG; J. S. TIEN

2000-01-01

164

Two-link swimming using buoyant orientation  

E-print Network

The scallop theorem posits that a two-link system immersed in a fluid at low Reynolds number cannot achieve any net translation via cyclic changes in its hinge angle. Here, we propose an approach to “breaking” this theorem, ...

Burton, Lisa Janelle

165

Turbulent Structure Dynamics of Buoyant and Non-Buoyant Pulsed Jet Diffusion Flames  

Microsoft Academic Search

The flame structure dynamics of strongly pulsed, turbulent diffusion flames were examined experimentally in a co-flow combustor. High-speed visual imaging and thermocouple measurements were performed to determine celerity, defined as as being the bulk velocity of a given flame puff structure in the large-scale, turbulent flame structures. Tests were conducted in normal gravity and microgravity with a fixed fuel injection

Mathieu Fregeau; James C. Hermanson; Dennis P. Stocker; Uday G. Hegde

2010-01-01

166

MEASUREMENT OF BUOYANT JET ENTRAINMENT FROM SINGLE AND MULTIPLE SOURCES  

EPA Science Inventory

An experimental investigation was conducted to determine the dilution characteristics of single and multiple discharges typical of modern natural and mechanical draft cooling towers. Simultaneous measurements of velocity and tracer concentration profiles were taken at various dow...

167

Research papers Phytoplankton productivity in a turbid buoyant coastal plume  

E-print Network

Sciences, School of Environment and Biological Sciences, Rutgers University, New Brunswick, NJ 08901, USA b and Biological Sciences, Rutgers University, New Brunswick, NJ 08903-0231, USA a r t i c l e i n f o Article Marine Sciences Department, University of Delaware, Lewes, DE 19958, USA c University of Florida

168

Pneumatic raft automatically reforms after rupture of buoyant member  

NASA Technical Reports Server (NTRS)

Unique, inflated, expandable socks are attached within the inflated chamber of a raft or a float in such a way that collapse of the chamber wall through damage, causes the adjacent sock to expand and restore the original configuration.

Radnofsky, M. I.; Shewmake, G. A.

1968-01-01

169

Buoyant plumes with inertial and chemical reaction-driven forcing  

E-print Network

-driven to momentum-driven flow. Regardless of the driving mechanism, forced plumes were found to exhibit a single was found ii #12;to depend on the dominating driving mechanism. Confined heads were produced by buoyancy for providing so many distractions from my work throughout this journey. I would like to express my deepest

Morris, Stephen W.

170

Infrared Imagery Applied to A Large Buoyant Plume  

Microsoft Academic Search

The possibility of applying infrared imagery to the study of a large, hot plume materialized by carbon particles resulting from the incomplete combustion of fuel oil is investigated.In a specific case (the PROSERPINE experiment), due to the high carbon particle content, the lower part of the plume acts as a semi-opaque target. Using an infrared camera equipped with a detector

J.-M. Brustet; B. Benech; P. Waldteufel

1981-01-01

171

A numerical study of interacting buoyant cooling-tower plumes  

Microsoft Academic Search

The compact design of mechanical cooling towers necessitates that the plumes are issued into the cross-wind in close proximity. An improved understanding of the interaction of adjacent plumes is therefore required for better design of such cooling towers, which may lead to a reduction in their environmental impact. This paper presents the results of a numerical investigation into the interaction

R. B. Bornoff; M. R. Mokhtarzadeh-Dehghan

2001-01-01

172

Buoyant Bubbles in a Cooling Intracluster Medium I. Hydrodynamic Bubbles  

E-print Network

Over the past several years, numerous examples of X-ray cavities coincident with radio sources have been observed in so-called "cool core" clusters of galaxies. Motivated by these observations, we explore the evolution and the effect of cavities on a cooling intracluster medium (ICM) numerically, adding relevant physics step by step. In this paper we present a first set of hydrodynamical, high resolution (1024^3 effective grid elements), three-dimensional simulations, together with two-dimensional test cases. The simulations follow the evolution of radio cavities, modeled as bubbles filled by relativistic plasma, in the cluster atmosphere while the ICM is subject to cooling. We find that the bubble rise retards the development of a cooling flow by inducing motions in the ICM which repeatedly displace the material in the core. Even bubbles initially set significantly far from the cluster center affect the cooling flow, although much later than the beginning of the simulation. The effect is, however, modest: the cooling time is increased by at most only 25%. As expected, the overall evolution of pure hydrodynamic bubbles is at odds with observations, showing that some additional physics has to be considered in order to match the data.

A. Gardini

2006-11-14

173

Metal mixing by buoyant bubbles in galaxy clusters  

E-print Network

Using a series of three-dimensional, hydrodynamic simulations on an adaptive grid, we have performed a systematic study on the effect of bubble-induced motions on metallicity profiles in clusters of galaxies. In particular, we have studied the dependence on the bubble size and position, the recurrence times of the bubbles, the way these bubbles are inflated and the underlying cluster profile. We find that in hydrostatic cluster models, the resulting metal distribution is very elongated along the direction of the bubbles. Anisotropies in the cluster or ambient motions are needed if the metal distribution is to be spherical. In order to parametrise the metal transport by bubbles, we compute effective diffusion coefficients. The diffusion coefficients inferred from our simple experiments lie at values of around $\\sim 10^{29}$ cm$^2$s$^{-1}$ at a radius of 10 kpc. The runs modelled on the Perseus cluster yield diffusion coefficients that agree very well with those inferred from observations.

E. Roediger; M. Brueggen; P. Rebusco; H. Boehringer; E. Churazov

2006-11-16

174

Buoyant Low Stretch Diffusion Flames Beneath Cylindrical PMMA Samples  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

175

PIV Measurements in Weakly Buoyant Gas Jet Flames  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

176

Time-dependent buoyant puff model for explosive sources  

SciTech Connect

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%.

Kansa, E.J.

1997-10-01

177

46 CFR 131.870 - Life floats and buoyant apparatus.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the float or apparatus. This number...

2010-10-01

178

46 CFR 131.870 - Life floats and buoyant apparatus.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the float or apparatus. This number...

2013-10-01

179

46 CFR 131.870 - Life floats and buoyant apparatus.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the float or apparatus. This number...

2012-10-01

180

46 CFR 131.870 - Life floats and buoyant apparatus.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.870 Life floats...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the float or apparatus. This number...

2011-10-01

181

Label-free buoyant mass assays with suspended microchannel resonators  

E-print Network

Improved methods are needed for routine, inexpensive monitoring of biomarkers that could facilitate earlier detection and characterization of complex diseases like cancer. Development of new assay formats based on microfluidic, ...

Von Muhlen, Marcio Goldani

2010-01-01

182

Buoyant magnetic flux tubes enhance radiation in Z pinches  

PubMed

In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. We demonstrate that the enhanced energy coupling may be due to the buoyancy rise of toroidal magnetic flux tubes converging to the axis through the unstable pinch plasma. We derive an explicit formula for the enhanced dissipation rate and apply this formula to reconsider an old problem of power balance in a steady-state Z pinch, and then to analyze a new challenge of producing K-shell 3 to 10 keV radiation in long-pulse Z-pinch implosions. PMID:11019081

Rudakov; Velikovich; Davis; Thornhill; Giuliani; Deeney

2000-04-10

183

Continents as lithological icebergs: The importance of buoyant lithospheric roots  

USGS Publications Warehouse

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.

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

1997-01-01

184

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

Code of Federal Regulations, 2012 CFR

...Fibrous-glass-reinforced plastic, constructed of a polyester resin listed on the current Qualified Products List for MIL-P-21607E(SH) (incorporated by reference, see § 160.010-1 of this subpart), or accepted by the Commandant (CG-ENG-4) as...

2012-10-01

185

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

Code of Federal Regulations, 2013 CFR

...Fibrous-glass-reinforced plastic, constructed of a polyester resin listed on the current Qualified Products List for MIL-P-21607E(SH) (incorporated by reference, see § 160.010-1 of this subpart), or accepted by the Commandant (CG-ENG-4) as...

2013-10-01

186

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

187

Modelling the fate and transport of negatively buoyant stormriver water in small multi-basin lakes  

E-print Network

with steep bathymetry (Toolik Lake, AK) are simulated using a Cartesian hydrodynamic model based are compared with results from previous analytical and laboratory studies and with field observations. The grid of storm events in small lakes with several interconnected basins using coupled biological measurements

California at Santa Barbara, University of

188

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

Code of Federal Regulations, 2011 CFR

...MIL-P-40619. (c) The external protective covering must be— (1) Fibrous-glass-reinforced plastic, constructed of a polyester resin listed on the current Qualified Products List for MIL-P-21607, or accepted by the Commandant (G-MSE) as...

2011-10-01

189

Plume Rise and Dispersion of Emissions from Low Level Buoyant Sources in Urban Areas  

E-print Network

Power Station, Chicago II were simulated in the wind tunnelwind direction) makes it significantly difficult (almost impossible with the current available computational power)wind speed and stack heat emission rate are the most significant parameters determining the plume rise from large power

Pournazeri, Sam

2012-01-01

190

A fast 3D particle method for simulations of buoyant and reacting flows  

E-print Network

This thesis describes progress in several areas related to three dimensional vortex methods and their application to multiphysics problems. The first is the solution of a generic scalar transport equation by advecting and ...

Schlegel, Fabrice

2007-01-01

191

A PDF DISPERSION MODEL FOR BUOYANT PLUMES IN THE CONVECTIVE BOUNDARY LAYER (R823419)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

192

Long-Lived, Maneuverable, Semi-Buoyant Platform for Venus Upper Atmosphere Exploration  

NASA Astrophysics Data System (ADS)

This presentation discusses the continued development of the Northrop Grumman/L’GARDE team’s long-lived, maneuverable platform to explore the Venus upper atmosphere. It focuses on the overall mission architecture and concept of operations.

Lee, G.; Sokol, D.; Polidan, R.; Bolisay, L.; Barnes, N.

2014-06-01

193

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

194

Concentration field and turbulent fluxes during the mixing of two buoyant plumes  

NASA Astrophysics Data System (ADS)

In this work an experimental study of mixing of two identical plumes, carried out in a turbulent neutral boundary layer generated in a wind tunnel, is presented. Measurements have been performed with fast flame ionisation detectors (FFIDs) and a two-component Laser-Doppler Anemometer system. Results allow the study of both the average and the fluctuating concentration field, including the turbulent vertical and longitudinal mass fluxes, in single plumes and during the interaction of two identical plumes. This information gives insight into the details of the mixing phase of the two plumes. Results of trajectories and additional rise (due to plume interactions) have been compared with previous measurements carried out in laminar cross-flows, showing similar behaviour. Concentration distributions in plume cross-sections in turbulent cross-flows differ from those measured in laminar cross-flows. Average vertical and longitudinal velocity measurements into the plume core show the strength of the shielding effect of the upwind plume and some details of interaction between the counter-rotating vortex pairs (CVPs). For large values of the alignment angle ?, between the line joining the stacks and the cross-flow, an average negative vertical velocity is measured in the middle of the plume even if its centre of mass is rising. This downward velocity is induced by the slow interaction of the CVPs and generates a vertical stretching of the plume and negative rise enhancement. Vertical turbulent fluxes change sign on the plume centreline and are of opposite sign with respect to the longitudinal turbulent fluxes. Results indicate a good linearity between vertical turbulent fluxes and concentration gradients, with different proportionality for the top and bottom parts of the plume (especially in the near field) indicating that dispersion could be described by a gradient-transfer model.

Contini, Daniele; Hayden, Paul; Robins, Alan

195

The Heads and Tails of Buoyant Autocatalytic Balls Michael C. Rogers1  

E-print Network

. In the presence of gravity, a front configuration where less dense product solution is beneath denser reactant-enhanced propagation of the IAA front has been carefully studied in various geometries. In thin vertical tubes, the relative strengths of the buoyancy and viscous forces due to the confining walls of the tube con- trol

Morris, Stephen W.

196

Pore-Scale Modeling of Reactive-Multiphase-Buoyant Flow for Carbon Capture and Storage  

NASA Astrophysics Data System (ADS)

Physical and geochemical processes at multiple scales are yet to be understood for the storage of carbon dioxide (CO2) in aquifers and the concomitant mitigation of CO2 concentration in the atmosphere. In deep saline aquifers, the pores in the potential aquifers for CO2 storage are initially filled with saline water (brine). The entrapment of brine in pores after injection of CO2 is controlled by capillary forces and by the inertial force driving CO2 inside the carbonate aquifer. The entrapped/residual brine will be a site for geochemical reactions which could alter the pore network and/or the permeability of the formation. Therefore, the pore-scale understanding of displacement of resident brine by CO2 is critical to evaluate the storage efficiency of carbonate aquifers and to quantify any dissolution or precipitation of minerals (e.g., gypsum, calcite, dolomite). In this project, we have developed a multiphase flow model, based on the lattice Boltzmann equation, that can describe pore-scale displacement of brine by invading CO2. The multiphase flow model is applied to three different pore networks saturated with brine. The amount of brine trapped after invasion of the domain by CO2 is strongly dependent on the pore network. We also examine the effects of CO2 density and viscosity (which depend on formation temperature and pressure) on the amount of entrapped brine. Only by resolving the flow at the pore scale can we predict the residual brine saturation and other parameters which control CO2 sequestration in deep saline aquifers. Future work will focus on coupling the pore-scale multiphase flow model to a chemistry model to predict mineral dissolution and precipitation.

Anwar, S.; Cunningham, J. A.; Trotz, M.; Thomas, M. W.; Stewart, M.

2010-12-01

197

Average centreline temperatures of a buoyant pool fire obtained by image processing of video recordings  

Microsoft Academic Search

Images from a standard video camera are used to obtain an average centreline temperature distribution of simulated pool fires. By using a novel technique, characteristic length scales are extracted from the flame images. With this information and the use of empirical correlations, the mean centreline temperature distribution is obtained. The range of validity of this technique is determined by conducting

L. Audouin; G. Kolb; J. L. Torero; J. M. Most

1995-01-01

198

Slip-velocity and drag of large neutrally-buoyant particles in turbulent flows  

E-print Network

We discuss possible definitions for a slip velocity that describes the relative motion between large particles and a turbulent flow. This definition is necessary because the slip velocity used in the standard drag model fails when particle size falls within the inertial subrange of ambient turbulence. By decomposing drag into steady and stochastic components, we obtain both a steady slip velocity and a fluctuating slip velocity. From this decomposition, we propose two definitions for stochastic slip velocity. These definitions were selected in part due to their simplicity: they do not require filtration of the fluid phase velocity field, nor do they require the construction of conditional averages on particle locations. A key benefit of this simplicity is that the stochastic slip velocity proposed here can be calculated equally well for laboratory, field, and numerical experiments. The stochastic slip velocity allows the definition of a Reynolds number that should indicate whether large particles in turbulent...

Bellani, Gabriele

2012-01-01

199

Sink fast and swim harder! Round-trip cost-of-transport for buoyant divers.  

PubMed

Efficient locomotion between prey resources at depth and oxygen at the surface is crucial for breath-hold divers to maximize time spent in the foraging layer, and thereby net energy intake rates. The body density of divers, which changes with body condition, determines the apparent weight (buoyancy) of divers, which may affect round-trip cost-of-transport (COT) between the surface and depth. We evaluated alternative predictions from external-work and actuator-disc theory of how non-neutral buoyancy affects round-trip COT to depth, and the minimum COT speed for steady-state vertical transit. Not surprisingly, the models predict that one-way COT decreases (increases) when buoyancy aids (hinders) one-way transit. At extreme deviations from neutral buoyancy, gliding at terminal velocity is the minimum COT strategy in the direction aided by buoyancy. In the transit direction hindered by buoyancy, the external-work model predicted that minimum COT speeds would not change at greater deviations from neutral buoyancy, but minimum COT speeds were predicted to increase under the actuator disc model. As previously documented for grey seals, we found that vertical transit rates of 36 elephant seals increased in both directions as body density deviated from neutral buoyancy, indicating that actuator disc theory may more closely predict the power requirements of divers affected by gravity than an external work model. For both models, minor deviations from neutral buoyancy did not affect minimum COT speed or round-trip COT itself. However, at body-density extremes, both models predict that savings in the aided direction do not fully offset the increased COT imposed by the greater thrusting required in the hindered direction. PMID:23014571

Miller, Patrick J O; Biuw, Martin; Watanabe, Yuuki Y; Thompson, Dave; Fedak, Mike A

2012-10-15

200

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

SciTech Connect

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.

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

1981-01-01

201

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

NASA Technical Reports Server (NTRS)

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.

Grant, F. C.

1973-01-01

202

Influence of a buoyant river plume on phytoplankton nutrient dynamics: What controls standing stocks and productivity?  

E-print Network

, treatments consisting of control, added nitrate, and added nitrate with 0.45 mm filtered plume water were of these stations, nutrient (nitrate, ammonium, and ammonium inhibition of nitrate) kinetics were obtained, as well as carbon-based estimates of productivity. For all experiments, nitrogen (nitrate) was clearly controlling

Hickey, Barbara

203

UTILITY OF BUOYANT PLUME MODELS IN PREDICTING THE INITIAL DILUTION OF DRILLING FLUIDS  

EPA Science Inventory

Three computer programs, PLUME, OUTPLM, and DKHPLM, have been used by the U.S. Environmental Protection Agency and municipalities to estimate initial dilutions of sewage discharged into marine environments. odification of the input parameters for the three programs, while maintai...

204

Interferometric measurement technique for the temperature field of axisymmetric buoyant phenomena.  

PubMed

A method is described to measure the temperature field of axisymmetric laminar thermals, plumes, and starting plume caps in a liquid. The sample liquid is placed in a Mach-Zender interferometer, and an infinite-fringe interferogram is recorded on photographic film. By comparison with a bar pattern interferogram, the fringe shift field was measured to an accuracy of +/-0.02. The Bockasten series approximation of the Abel transformation was applied to the fringe shift field to obtain the radial refractive index variation field, which in turn could be related to the temperature variation field through an empirical relationship. Temperature accuracies in the range of +/-0.05 to +/-0.5 degrees C were obtained. The radial temperature profile of the plume was found to be monotonically decreasing, while the cap had a local maximum offset from the axis. PMID:20203867

Boxman, R L; Shlien, D J

1978-09-01

205

Ascent and emplacement of buoyant magma bodies in brittle-ductile upper crust  

Microsoft Academic Search

The emplacement of silicic magma bodies in the upper crust may be controlled by density (such that there is no buoyancy to drive further ascent) or temperature (such that surrounding rocks are too cold to deform significantly over geological timescales). Evidence for the latter control is provided by negative gravity anomalies over many granitic plutons. Conditions of diapir ascent and

Evgene Burov; Claude Jaupart; Laurent Guillou-Frottier

2003-01-01

206

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

NASA Astrophysics Data System (ADS)

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 under specific circumstances, lacking the generality of proper scientific explanations. Complete understanding of fundamental reasons behind objects' sinking or floating requires complex knowledge, including the analysis of the relationship between buoyancy and the force of gravity.

Radovanovic, Jelena; Slisko, Josip

2012-10-01

207

46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the raft or apparatus. Each raft or...

2011-10-01

208

46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the raft or apparatus. Each raft or...

2012-10-01

209

46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the raft or apparatus. Each raft or...

2013-10-01

210

46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable...at least 38 millimeters (1-1/2 inches) high and in a color contrasting to that of the raft or apparatus. Each raft or...

2010-10-01

211

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

Microsoft Academic Search

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

Perry A. Meyer; Charles W. Stewart

2001-01-01

212

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

Code of Federal Regulations, 2010 CFR

...VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts,...

2010-10-01

213

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

Code of Federal Regulations, 2011 CFR

...VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts,...

2011-10-01

214

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

Code of Federal Regulations, 2012 CFR

...VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts,...

2012-10-01

215

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

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of inflatable liferafts,...

2012-10-01

216

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

Code of Federal Regulations, 2013 CFR

...VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts,...

2013-10-01

217

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

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of inflatable liferafts,...

2013-10-01

218

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

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of inflatable liferafts,...

2010-10-01

219

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

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) OPERATIONS Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of inflatable liferafts,...

2011-10-01

220

Meeting the Skills Needs of a Buoyant Economy: Apprenticeship--The Irish Experience  

ERIC Educational Resources Information Center

The Irish economy has grown at an unprecedented rate over the last decade and the demand for skilled workers has increased dramatically. The Irish Standards-Based Apprenticeship (SBA) system has been one of the cornerstones of intermediate skills development with the capacity to produce high-quality craft workers and in sufficient numbers to meet…

O'Connor, Len

2006-01-01

221

A Buoyant Pop Net for Accurately Sampling Fish at Artificial Habitat Structures  

Microsoft Academic Search

We developed and evaluated the efficiency of a remotely operated pop net for sampling the entire fish assemblage associated with fish-attracting structures. The pop net collected an average of 99% of subadult and adult bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides available to capture in pool tests conducted at 3–13°C and various light intensities. There was no evidence of

Eric W. Larson; David L. Johnson; William E. Lynch Jr

1986-01-01

222

Numerical study of wall effects on buoyant gas-bubble rise in a liquid-filled finite cylinder  

PubMed Central

The wall effects on the axisymmetric rise and deformation of an initially spherical gas bubble released from rest in a liquid-filled, finite circular cylinder are numerically investigated. The bulk and gas phases are considered incompressible and immiscible. The bubble motion and deformation are characterized by the Morton number (Mo), Eötvös number (Eo), Reynolds number (Re), Weber number (We), density ratio, viscosity ratio, the ratios of the cylinder height and the cylinder radius to the diameter of the initially spherical bubble (H* = H/d0, R* = R/d0). Bubble rise in liquids described by Eo and Mo combinations ranging from (1,0.01) to (277.5,0.092), as appropriate to various terminal state Reynolds numbers (ReT) and shapes have been studied. The range of terminal state Reynolds numbers includes 0.02 < ReT < 70. Bubble shapes at terminal states vary from spherical to intermediate spherical-cap–skirted. The numerical procedure employs a front tracking finite difference method coupled with a level contour reconstruction of the front. This procedure ensures a smooth distribution of the front points and conserves the bubble volume. For the wide range of Eo and Mo examined, bubble motion in cylinders of height H* = 8 and R* ? 3, is noted to correspond to the rise in an infinite medium, both in terms of Reynolds number and shape at terminal state. In a thin cylindrical vessel (small R*), the motion of the bubble is retarded due to increased total drag and the bubble achieves terminal conditions within a short distance from release. The wake effects on bubble rise are reduced, and elongated bubbles may occur at appropriate conditions. For a fixed volume of the bubble, increasing the cylinder radius may result in the formation of well-defined rear recirculatory wakes that are associated with lateral bulging and skirt formation. The paper includes figures of bubble shape regimes for various values of R*, Eo, Mo, and ReT. Our predictions agree with existing results reported in the literature. PMID:17930342

Mukundakrishnan, Karthik; Quan, Shaoping; Eckmann, David M.; Ayyaswamy, Portonovo S.

2009-01-01

223

Buoyant and capillary natural convection in infinite horizontal liquid layers heated laterally. [application to space manufactured containerless melts  

NASA Technical Reports Server (NTRS)

Solutions are presented for the equations describing natural convection in a planar, horizontal layer of liquid with a constant, linear temperature gradient along the unbounded top and bottom surfaces. Both buoyancy and capillary forces are considered to drive thermal convection. The results are compared to earlier analyses for bounded liquid layers and then applied to containerless metal melts undergoing solidification in the microgravity environment of near-earth orbit.

Bourgeois, S. V.

1975-01-01

224

A smoothed particle hydrodynamics study on the electrohydrodynamic deformation of a droplet suspended in a neutrally buoyant Newtonian fluid  

NASA Astrophysics Data System (ADS)

In this paper, we have presented a 2D Lagrangian two-phase numerical model to study the deformation of a droplet suspended in a quiescent fluid subjected to the combined effects of viscous, surface tension and electric field forces. The electrostatics phenomena are coupled to hydrodynamics through the solution of a set of Maxwell equations. The relevant Maxwell equations and associated interface conditions are simplified relying on the assumptions of the so-called leaky dielectric model. All governing equations and the pertinent jump and boundary conditions are discretized in space using the incompressible Smoothed Particle Hydrodynamics method with improved interface and boundary treatments. Upon imposing constant electrical potentials to upper and lower horizontal boundaries, the droplet starts acquiring either prolate or oblate shape, and shows rather different flow patterns within itself and in its vicinity depending on the ratios of the electrical permittivities and conductivities of the constituent phases. The effects of the strength of the applied electric field, permittivity, surface tension, and the initial droplet radius on the droplet deformation parameter have been investigated in detail. Numerical results are validated by two highly credential analytical results which have been frequently cited in the literature. The numerically and analytically calculated droplet deformation parameters show good agreement for small oblate and prolate deformations. However, for some higher values of the droplet deformation parameter, numerical results overestimate the droplet deformation parameter. This situation was also reported in literature and is due to the assumption made in both theories, which is that the droplet deformation is rather small, and hence the droplet remains almost circular. Moreover, the flow circulations and their corresponding velocities in the inner and outer fluids are in agreement with theories.

Shadloo, M. S.; Rahmat, A.; Yildiz, M.

2013-09-01

225

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

SciTech Connect

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)

Boulanger, Joan [Gas Turbine Laboratory, Institute for Aerospace Research, Ottawa, Ontario (Canada)

2010-04-15

226

(Revised May 22, 2012) (1) To experimentally determine the relationship between the buoyant forces on objects that  

E-print Network

(Revised May 22, 2012) Buoyancy GOALS (1) To experimentally determine the relationship between of the aluminum and wood cylinders from your data and compare them to handbook values. INTRODUCTION Buoyancy and for keeping hot air balloons in flight. In the absence of other forces, the net force, FNet, acting

Collins, Gary S.

227

(Revised May 22, 2012) (1) To experimentally determine the relationship between the buoyant forces on an object that  

E-print Network

(Revised May 22, 2012) Buoyancy GOALS (1) To experimentally determine the relationship between Buoyancy is the name given to the force that arises when an object displaces a fluid (either a gas sinking and for keeping hot air balloons in flight. In the absence of other forces, the net force, FNet

Collins, Gary S.

228

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

PubMed

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

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

2011-11-01

229

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

NASA Astrophysics Data System (ADS)

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 (? ? 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.

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

2013-12-01

230

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

PubMed Central

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

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

2011-01-01

231

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

PubMed

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. PMID:25147021

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

2014-10-15

232

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)

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.

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

2014-10-01

233

Development of vapor-dispersion models for nonneutrally buoyant gas mixtures - analysis of TFI/NH/sub 3/ test data. Final report, March 1986-March 1987  

SciTech Connect

Field-scale releases of pressurized anhydrous ammonia were performed by the Lawrence Livermore National Laboratories in 1983 for the U.S. Coast Guard, the Fertilizer Institute, and Environment Canada. Release rates for the four experiments ranged between 80 and 130 kilograms per second. The pressurized liquid-ammonia jet formed a denser-than-air aerosol cloud. A method of determining the relative importance of jet and nonjet dispersion processes is discussed. The data from these experiments were analyzed to determine the mass flux of ammonia and the lateral and vertical concentration profile parameters for the cloud (sigma y and sigma z for the Gaussian plume model and SY and SZ for DEGADIS) at 800 meters downwind. These observed values of maximum concentration and concentration profile parameters were compared with DEGADIS and Gaussian plume model predictions. (DEGADIS is an atmospheric dispersion model designed to account for the influences of denser-than-air gases.) In addition, analysis of the experimental data indicated heat transfer to the aerosol cloud was insignificant although the cloud temperature was as low as -60/sup 0/.

Spicer, T.O.; Havens, J.

1988-10-01

234

46 CFR 160.060-8 - Marking.  

Code of Federal Regulations, 2010 CFR

...EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-8 Marking. ...tested in accordance with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant force...

2010-10-01

235

46 CFR 160.060-8 - Marking.  

Code of Federal Regulations, 2011 CFR

...EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-8 Marking. ...tested in accordance with U.S. Coast Guard regulations. Polyethylene foam buoyant material provides a minimum buoyant force...

2011-10-01

236

46 CFR 160.060-1 - Incorporation by reference.  

Code of Federal Regulations, 2011 CFR

...EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-1 Incorporation...Coast Guard Specification: 164.013—Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b)...

2011-10-01

237

46 CFR 160.060-1 - Incorporation by reference.  

Code of Federal Regulations, 2010 CFR

...EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-1 Incorporation...Coast Guard Specification: 164.013—Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) (b)...

2010-10-01

238

46 CFR 160.060-7 - Inspections and tests-standard and nonstandard vests. 1  

Code of Federal Regulations, 2012 CFR

...Unicellular Polyethylene Foam, Adult and Child § 160.060-7 Inspections and...fresh water; the inserts from the child medium size buoyant vests shall provide...buoyancy; and the inserts from the child small size buoyant vests shall...

2012-10-01

239

46 CFR 160.060-7 - Inspections and tests-standard and nonstandard vests. 1  

Code of Federal Regulations, 2011 CFR

...Unicellular Polyethylene Foam, Adult and Child § 160.060-7 Inspections and...fresh water; the inserts from the child medium size buoyant vests shall provide...buoyancy; and the inserts from the child small size buoyant vests shall...

2011-10-01

240

46 CFR 160.060-7 - Inspections and tests-standard and nonstandard vests. 1  

Code of Federal Regulations, 2010 CFR

...Unicellular Polyethylene Foam, Adult and Child § 160.060-7 Inspections and...fresh water; the inserts from the child medium size buoyant vests shall provide...buoyancy; and the inserts from the child small size buoyant vests shall...

2010-10-01

241

46 CFR 160.060-7 - Inspections and tests-standard and nonstandard vests. 1  

Code of Federal Regulations, 2013 CFR

...Unicellular Polyethylene Foam, Adult and Child § 160.060-7 Inspections and...fresh water; the inserts from the child medium size buoyant vests shall provide...buoyancy; and the inserts from the child small size buoyant vests shall...

2013-10-01

242

33 CFR 175.23 - Serviceable condition.  

Code of Federal Regulations, 2010 CFR

...coatings, that are large enough to allow the loss of buoyant material; (2) Buoyant material that has become hardened, non-resilient, permanently compressed, waterlogged, oil-soaked, or which shows evidence of fungus or mildew; or (3) Loss...

2010-07-01

243

46 CFR 164.013-4 - Samples submitted for acceptance.  

Code of Federal Regulations, 2010 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-4 Samples submitted for acceptance. Application...

2010-10-01

244

46 CFR 164.013-5 - Acceptance tests.  

Code of Federal Regulations, 2010 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-5 Acceptance tests. Manufacturers shall ensure that...

2010-10-01

245

46 CFR 164.013-4 - Samples submitted for acceptance.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-4 Samples submitted for acceptance. Application...

2011-10-01

246

46 CFR 164.013-7 - Marking.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-7 Marking. (a) General. The manufacturer...

2011-10-01

247

46 CFR 164.013-2 - Incorporation by reference.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-2 Incorporation by reference. (a) Certain...

2011-10-01

248

46 CFR 164.013-5 - Acceptance tests.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-5 Acceptance tests. Manufacturers shall ensure that...

2011-10-01

249

46 CFR 164.013-7 - Marking.  

Code of Federal Regulations, 2010 CFR

...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-7 Marking. (a) General. The manufacturer...

2010-10-01

250

46 CFR 160.048-1 - Incorporation by reference.  

Code of Federal Regulations, 2012 CFR

...Specification for a Buoyant Cushion, Fibrous Glass § 160.048-1 Incorporation by reference...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,...

2012-10-01

251

46 CFR 160.048-7 - Procedure for approval.  

Code of Federal Regulations, 2012 CFR

...Specification for a Buoyant Cushion, Fibrous Glass § 160.048-7 Procedure for approval...and which are filled with kapok or fibrous glass in accordance with § 160.048-4(c...manufacturer for each kapok or fibrous glass buoyant cushion he proposes to...

2012-10-01

252

46 CFR 160.048-7 - Procedure for approval.  

Code of Federal Regulations, 2011 CFR

...Specification for a Buoyant Cushion, Fibrous Glass § 160.048-7 Procedure for approval...and which are filled with kapok or fibrous glass in accordance with § 160.048-4(c...manufacturer for each kapok or fibrous glass buoyant cushion he proposes to...

2011-10-01

253

The gas content and buoyancy of strombolian ash plumes  

Microsoft Academic Search

Plinian plumes erupt with a bulk density greater than that of air, and depend upon air entrainment during their gas-thrust phase to become buoyant; if entrainment is insufficient, the column collapses into a potentially deadly pyroclastic flow. This study shows that strombolian ash plumes can be erupted in an initially buoyant state due to their extremely high initial gas content,

Matthew Patrick

2007-01-01

254

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...

255

Field calibration of a formula for entrance mixing of river inflows to lakes: Lake Taupo, North Island, New Zealand  

Microsoft Academic Search

Field measurements were used to validate predictions for the initial dilution of negatively buoyant, cold?water inflows to Lake Taupo, as part of a study to quantify mixing processes associated with the two largest inflows to the lake. The predictions were made using a formulation originally derived for positively buoyant, warm?water inflows to cooling ponds. The formulation predicts the total dilution

Robert H. Spigel; Max Gibbs; Scott Stephens; Barry Waugh

2005-01-01

256

VORTEX FORMATION BY SUCCESSIVE THERMALS: A NUMERICAL SIMULATION  

Microsoft Academic Search

The purpose of this research is to investigate, by means of numerical simulation experiments, the complex inter- actions between consecutive toroidally circulating buoyant elements (thermals) when these occur in either rotating or nonrotating environments. The study includes both the vortex formation process and the effect that this process has on the properties of the one or more buoyant elements involved

EUGENE M. WILKINS; YOSHIKAZU SASAKI; ROGER H. SCHAUSS

1971-01-01

257

Disdrometer and dual-polarization radar measurements in tornadic storms  

E-print Network

! · Tx2: 45 Rx2: Hand V ZDR, Phi-DP, Rho-HV! · Get independent full power V(1/H 2/45)! · Get independent radar observations): What is the optimal temperature?! Cooler! (less buoyant)! Warmer! (more buoyant

258

Pelvic Girdle Shape Predicts Locomotion and Phylogeny in Batoids  

E-print Network

; Fig. 1c). However, some teleost fish (e.g., batfish, flying gurnards, frogfish, and lungfish; (Helfman on positively buoyant bony fish, the same relationship does not appear to exist. However, within the negatively buoyant elasmo- branch fishes, benthic batoids employ pelvic fin bottom- walking and punting as primary

Kajiura, Stephen

259

Parametric study of modern airship productivity  

NASA Technical Reports Server (NTRS)

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.

Ardema, M. D.; Flaig, K.

1980-01-01

260

Active-specific immunotherapy for non-small cell lung cancer  

PubMed Central

Non-small cell lung cancer constitutes about 85% of all newly diagnosed cases of lung cancer and continues to be the leading cause of cancer-related deaths worldwide. Standard treatment for this devastating disease, such as systemic chemotherapy, has reached a plateau in effectiveness and comes with considerable toxicities. For all stages of disease fewer than 20% of patients are alive 5 years after diagnosis; for metastatic disease the median survival is less than one year. Until now, the success of active-specific immunotherapy for all tumor types has been sporadic and unpredictable. However, the active-specific stimulation of the host’s own immune system still holds great promise for achieving non-toxic and durable antitumor responses. Recently, sipuleucel-T (Provenge®; Dendreon Corp., Seattle, WA) was the first therapeutic cancer vaccine to receive market approval, in this case for advanced prostate cancer. Other phase III clinical trials using time-dependent endpoints, e.g. in melanoma and follicular lymphoma, have recently turned out positive. More sophisticated specific vaccines have now also been developed for lung cancer, which, for long, was not considered an immune-sensitive malignancy. This may explain why advances in active-specific immunotherapy for lung cancer lag behind similar efforts in renal cell cancer, melanoma or prostate cancer. However, various vaccines are now being evaluated in controlled phase III clinical trials, raising hopes that active-specific immunotherapy may become an additional effective therapy for patients with lung cancer. This article reviews the most prominent active-specific immunotherapeutic approaches using protein/peptide, whole tumor cells, and dendritic cells as vaccines for lung cancer. PMID:22263073

Winter, Hauke; van den Engel, Natasja K.; Rusan, Margareta; Schupp, Nina; Poehlein, Christian H.; Hu, Hong-Ming; Hatz, Rudolf A.; Urba, Walter J.; Jauch, Karl-Walter; Fox, Bernard A.; Ruttinger, Dominik

2011-01-01

261

Steady advance of stem cell therapies: report from the 2011 World Stem Cell Summit, Pasadena, California, October 3-5.  

PubMed

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. PMID:22175514

Swan, Melanie

2011-12-01

262

Translational Approaches towards Cancer Gene Therapy: Hurdles and Hopes  

PubMed Central

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

Barar, Jaleh; Omidi, Yadollah

2012-01-01

263

46 CFR 160.048-3 - Materials.  

Code of Federal Regulations, 2013 CFR

...EQUIPMENT Specification for a Buoyant Cushion, Fibrous Glass § 160.048-3 Materials. (a) General...subchapter and shall be properly processed. (c) Fibrous glass. The fibrous glass shall comply with the requirements of...

2013-10-01

264

46 CFR 164.013-1 - Scope.  

Code of Federal Regulations, 2010 CFR

...APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...testing and inspection requirements for polyethylene foam used in the construction of...019 of this chapter. (b) All polyethylene foams accepted under this subpart...

2010-10-01

265

46 CFR 160.060-4 - Materials-nonstandard vests.  

Code of Federal Regulations, 2010 CFR

...CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-4 Materials—nonstandard vests. (a) General. All materials used...

2010-10-01

266

46 CFR 164.013-6 - Production tests, inspections, and marking.  

Code of Federal Regulations, 2010 CFR

...SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-6...Manufacturers shall provide in-plant quality control of polyethylene foam in accordance with the requirements of §...

2010-10-01

267

46 CFR 160.060-4 - Materials-nonstandard vests.  

Code of Federal Regulations, 2011 CFR

...CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-4 Materials—nonstandard vests. (a) General. All materials used...

2011-10-01

268

46 CFR 160.060-9 - Recognized laboratory.  

Code of Federal Regulations, 2011 CFR

...CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-9 Recognized laboratory. (a) A manufacturer seeking Coast Guard...

2011-10-01

269

46 CFR 160.060-9 - Recognized laboratory.  

Code of Federal Regulations, 2010 CFR

...CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Specification for a Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-9 Recognized laboratory. (a) A manufacturer seeking Coast Guard...

2010-10-01

270

46 CFR 164.013-1 - Scope.  

Code of Federal Regulations, 2011 CFR

...APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal...testing and inspection requirements for polyethylene foam used in the construction of...019 of this chapter. (b) All polyethylene foams accepted under this subpart...

2011-10-01

271

46 CFR 164.013-6 - Production tests, inspections, and marking.  

Code of Federal Regulations, 2011 CFR

...SPECIFICATIONS AND APPROVAL MATERIALS Foam, Unicellular Polyethylene (Buoyant, Slab, Slitted Trigonal Pattern) § 164.013-6...Manufacturers shall provide in-plant quality control of polyethylene foam in accordance with the requirements of §...

2011-10-01

272

46 CFR 160.077-2 - Definitions.  

Code of Federal Regulations, 2011 CFR

...inherently buoyant material. (e) Inflation medium means any solid, liquid, or gas, that...means a model AK-1, adult PFD; model CKM-1, child medium PFD; or model CKS-2, child small PFD, meeting the...

2011-10-01

273

46 CFR 160.060-6 - Construction-nonstandard vests.  

Code of Federal Regulations, 2011 CFR

...Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests...Three hundred and fifty cubic inches or more for a child medium size, for children weighing from 50 to 90 pounds. (3) Two...

2011-10-01

274

46 CFR 160.060-6 - Construction-nonstandard vests.  

Code of Federal Regulations, 2010 CFR

...Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests...Three hundred and fifty cubic inches or more for a child medium size, for children weighing from 50 to 90 pounds. (3) Two...

2010-10-01

275

46 CFR 160.077-2 - Definitions.  

Code of Federal Regulations, 2013 CFR

...inherently buoyant material. (e) Inflation medium means any solid, liquid, or gas, that...means a model AK-1, adult PFD; model CKM-1, child medium PFD; or model CKS-2, child small PFD, meeting the...

2013-10-01

276

46 CFR 160.060-6 - Construction-nonstandard vests.  

Code of Federal Regulations, 2012 CFR

...Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests...Three hundred and fifty cubic inches or more for a child medium size, for children weighing from 50 to 90 pounds. (3) Two...

2012-10-01

277

46 CFR 160.077-2 - Definitions.  

Code of Federal Regulations, 2012 CFR

...inherently buoyant material. (e) Inflation medium means any solid, liquid, or gas, that...means a model AK-1, adult PFD; model CKM-1, child medium PFD; or model CKS-2, child small PFD, meeting the...

2012-10-01

278

46 CFR 160.060-6 - Construction-nonstandard vests.  

Code of Federal Regulations, 2013 CFR

...Buoyant Vest, Unicellular Polyethylene Foam, Adult and Child § 160.060-6 Construction—nonstandard vests...Three hundred and fifty cubic inches or more for a child medium size, for children weighing from 50 to 90 pounds. (3) Two...

2013-10-01

279

PUBLISHED ONLINE: 5 JUNE 2011 | DOI: 10.1038/NPHYS2010 The pirouette effect in turbulent flows  

E-print Network

). This is a manifestation of the `pirouette effect', well known from classical ballet or ice-skating. We used a particle tracking technique to follow several hundreds of nearly neutrally buoyant, 30 µm size polystyrene particles

Ahlers, Guenter

280

EXPERIMENTAL SIMULATION OF SINGLE AND MULTIPLE CELL COOLING TOWER PLUMES  

EPA Science Inventory

An experimental investigation was conducted to determine the dilution characteristics of single and multiple port buoyant discharges typical of modern natural and mechanical draft cooling towers. Simultaneous measurements of velocity and tracer concentration profiles were taken a...

281

A Tale of Two Spills: Novel Science and Policy Implications of an Emerging New Oil Spill Model  

E-print Network

The 2010 Deepwater Horizon oil release posed the challenges of two types of spill: a familiar spill characterized by buoyant oil, fouling and killing organisms at the sea surface and eventually grounding on and damaging ...

Adams, E. Eric

282

FLOCCULATION-FLOTATION AIDS FOR TREATMENT OF COMBINED SEWER OVERFLOWS  

EPA Science Inventory

The objectives of this study were to investigate the flocculation/flotation characteristics of combined sewer overflow through laboratory and field testing. The concept involves the introduction of chemicals and buoyant flotation aids into the overflow and the subsequent cofloccu...

283

46 CFR 133.10 - Applicability.  

Code of Federal Regulations, 2010 CFR

...lifejackets, and immersion suits; and (3) Offshore supply vessels may retain the arrangement of lifeboats, lifeboat davits, winches, inflatable liferafts, liferaft launching equipment, rescue boats, lifefloats, and buoyant apparatus previously...

2010-10-01

284

Syn-collisional delamination in convergent orogens: insights from lithospheric buoyancy and physical modeling  

E-print Network

zone in the lithosphere. Scaled physical models with a model continental crust weakly coupled to a lithospheric mantle containing net negatively buoyant mass delaminate during shortening. In contrast, weakly coupled models containing net positively...

Moore, Vernon Michael

2012-06-07

285

Oscillatory thermocapillary convection  

NASA Technical Reports Server (NTRS)

We study thermocapillary and buoyant thermocapillary convection in rectangular cavities with aspect ratio A = 4 and Pr = 0.015. Two separate problems are considered. The first is combined buoyant thermocapillary convection with a nondeforming interface. We establish neutral curves for transition to oscillatory convection in the Re-Gr plane. It is shown that while pure buoyant convection exhibits oscillatory behavior for Gr is greater than Gr(sub cr) (where Gr(sub cr) is defined for the pure buoyant problem), pure thermocapillary convection is steady within the range of parameters tested. In the second problem, we consider the influence of surface deformation on the pure thermocapillary problem. For the range of parameters considered, thermocapillary convection remained steady.

Mundrane, Michael R.; Zebib, Abdelfattah

1994-01-01

286

Low thermal Peclet number intraplate orogeny in central Australia  

E-print Network

[2]. Material advection through oro- genic belts tends to cool the deeper parts of the lithosphere, as happens when the advec- tion of the buoyant crustal material into the oro- gen exceeds its removal

Sandiford, Mike

287

ENVXR 202: EARTH, AIR, WATER EXPERIMENTAL PROJECTS for Water (W) 25 Feb 2003  

E-print Network

, with biological food chain active from microscopic plankton to large sea creatures and birds. At one end the ocean provides salty, dense water rich with nutiients; at the other, the river water is very buoyant and floats

288

Mantle Dynamics, Early Reservoir Formation and Degassing of the Martian Interior  

NASA Astrophysics Data System (ADS)

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.

Breuer, D.; Plesa, A.-C.; Grott, M.; Morschhauser, A.

2014-11-01

289

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...

290

Turbulent round jet under gravity waves  

E-print Network

The behavior of a neutrally buoyant horizontal turbulent round jet under a wavy environment was investigated. Progressive waves with different wave amplitudes in an intermediate water depth were used. The Particle Image Velocimetry (PIV) technique...

Ryu, Yong Uk

2012-06-07

291

How does the potential energy of a rising helium-filled balloon change?  

Microsoft Academic Search

I discuss why the buoyant force as given by Archimedes' principle is a conservative force with an associated potential energy. I then provide several arguments why a rising helium balloon loses potential energy.

David Keeports

2002-01-01

292

Experimentally Determining the Molar Mass of Carbon Dioxide Using a Mylar Balloon.  

ERIC Educational Resources Information Center

Describes how to determine the mass of a gas in a flexible, lightweight container and argues that the buoyant force of air needs to be taken into account. Recommends the use of mylar and describes equipment preparation. (DDR)

Jackson, Barbara Albers; Crouse, David J.

1998-01-01

293

46 CFR 196.34-15 - Shipboard stowage.  

Code of Federal Regulations, 2010 CFR

...Section 196.34-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Work Vests § 196.34-15 Shipboard stowage. (a) The approved buoyant work vests shall be...

2010-10-01

294

46 CFR 196.34-10 - Use.  

Code of Federal Regulations, 2010 CFR

...Section 196.34-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Work Vests § 196.34-10 Use. (a) Approved buoyant work vests are considered to be items of...

2010-10-01

295

46 CFR 196.34-5 - Approved types of work vests.  

Code of Federal Regulations, 2010 CFR

...Section 196.34-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Work Vests § 196.34-5 Approved types of work vests. (a) Each buoyant work vest carried...

2010-10-01

296

46 CFR 160.047-3 - Materials.  

Code of Federal Regulations, 2013 CFR

...1, film. (f) Tie tapes and body strap loops. The tie tapes and body strap loops for an adult or child size buoyant vest specified...The complete body strap assembly, including hardware, must have a breaking strength of 150...

2013-10-01

297

46 CFR 160.047-3 - Materials.  

Code of Federal Regulations, 2012 CFR

...1, film. (f) Tie tapes and body strap loops. The tie tapes and body strap loops for an adult or child size buoyant vest specified...The complete body strap assembly, including hardware, must have a breaking strength of 150...

2012-10-01

298

46 CFR 160.176-23 - Marking.  

Code of Federal Regulations, 2011 CFR

...manual and user's manual ). When fully inflated this lifejacket provides a minimum buoyant force of (insert the design buoyancy in lb. ). (d) Other Information. Each lifejacket must also be marked with the following information below the...

2011-10-01

299

46 CFR 160.002-5 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2011 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2011-10-01

300

Buoyancy and Archimedes Principle  

NSDL National Science Digital Library

Summary Buoyancy is based on Archimedes' Principle which states that the buoyant force acting upward on an object completely or partially immersed in a fluid equals the weight of the fluid displaced by the ...

301

46 CFR 160.005-5 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2011 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2011-10-01

302

46 CFR 160.055-7 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2012 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2012-10-01

303

46 CFR 160.055-7 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2011 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2011-10-01

304

46 CFR 160.027-2 - Type.  

Code of Federal Regulations, 2012 CFR

...requirements in subpart 160.010 of this chapter for a peripheral body type buoyant apparatus designed so that persons supported are only partially immersed (180 N (40 lb.) of buoyancy per person required). (b)...

2012-10-01

305

46 CFR 160.002-5 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2012 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2012-10-01

306

46 CFR 160.027-2 - Type.  

Code of Federal Regulations, 2011 CFR

...requirements in subpart 160.010 of this chapter for a peripheral body type buoyant apparatus designed so that persons supported are only partially immersed (180 N (40 lb.) of buoyancy per person required). (b)...

2011-10-01

307

46 CFR 160.002-5 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2013 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2013-10-01

308

46 CFR 160.055-7 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2013 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2013-10-01

309

46 CFR 160.005-5 - Sampling, tests, and inspections.  

Code of Federal Regulations, 2013 CFR

...with this section and § 160.001-5. (b) Buoyancy test. The buoyancy of the pad inserts from the life preserver shall...submersion must be at least 48 hours. (c) Buoyancy required. The buoyant pad inserts from...

2013-10-01

310

Unmanned Aircraft Guidance for Penetration of Pre-Tornadic Storms  

E-print Network

that it is negatively buoyant aloft. It is surmised that this negative buoyancy, if present in sufficient quantities this downdraft. Balloons cannot ascend through strong downdrafts and these flows are much too dangerous

Frew, Eric W.

311

How does the potential energy of a rising helium-filled balloon change?  

NASA Astrophysics Data System (ADS)

I discuss why the buoyant force as given by Archimedes' principle is a conservative force with an associated potential energy. I then provide several arguments why a rising helium balloon loses potential energy.

Keeports, David

2002-03-01

312

Mineralogy: Garnet goes hungry  

NASA Astrophysics Data System (ADS)

Sinking slabs of oceanic lithosphere often stagnate in Earth's mantle. Experiments show that common slab minerals transform to their high-pressure, high-density counterparts at very slow rates, thus keeping the slabs buoyant and impeding subduction.

Bina, Craig R.

2013-05-01

313

Effects of the pressure perturbation field in numerical models of unidirectionally sheared thunderstorm convection - Two versus three dimensions  

NASA Technical Reports Server (NTRS)

The physical roles of 'buoyant' and 'dynamic' pressure components, and the distinction between buoyant and hydrostatic pressure perturbations, are aspects of the pressure perturbation field in strongly sheared convective storms studied by means of two- and three-dimensional anelastic numerical modeling experiments with common environmental profiles. The pressure analysis clarifies the differences between two- and three-dimensional storms. In the main updraft, strong midlevel thermal buoyancy is partly opposed by a downward-perturbed vertical pressure gradient force. This, however, occurs to a much greater extent in two dimensions than in three, contributing to smaller net upward accelerations. While the buoyant and hydrostatic fields are intimately related to the total buoyancy distribution, the buoyant pressure perturbation is smoother and of lower amplitude than its hydrostatic counterpart. For the model experiments, this distinction is far greater in three dimensions than in two, in association with the smaller scale of the active convection in three dimensions.

Schlesinger, R. E.

1984-01-01

314

46 CFR 160.056-2 - Construction.  

Code of Federal Regulations, 2011 CFR

...225 pounds. (d) Seats. The rescue boat shall be fitted with three thwarts. The middle thwart shall be arranged as the rowing seat. (e) Internal buoyancy. Buoyant material of suitable unicellular plastic foam shall be installed in the...

2011-10-01

315

46 CFR 160.056-2 - Construction.  

Code of Federal Regulations, 2013 CFR

...225 pounds. (d) Seats. The rescue boat shall be fitted with three thwarts. The middle thwart shall be arranged as the rowing seat. (e) Internal buoyancy. Buoyant material of suitable unicellular plastic foam shall be installed in the...

2013-10-01

316

46 CFR 160.056-2 - Construction.  

Code of Federal Regulations, 2012 CFR

...225 pounds. (d) Seats. The rescue boat shall be fitted with three thwarts. The middle thwart shall be arranged as the rowing seat. (e) Internal buoyancy. Buoyant material of suitable unicellular plastic foam shall be installed in the...

2012-10-01

317

46 CFR 160.056-2 - Construction.  

Code of Federal Regulations, 2010 CFR

...225 pounds. (d) Seats. The rescue boat shall be fitted with three thwarts. The middle thwart shall be arranged as the rowing seat. (e) Internal buoyancy. Buoyant material of suitable unicellular plastic foam shall be installed in the...

2010-10-01

318

Quantifying Particle Coatings Using High-Precision Mass Measurements  

E-print Network

We present a general method to quantify coatings on microparticle surfaces based on the additional mass. Particle buoyant mass is determined in a solution with a density that is nearly equivalent to that of the core particle, ...

Knudsen, Scott Michael

319

Intracellular Water Exchange for Measuring the Dry Mass, Water Mass and Changes in Chemical Composition of Living Cells  

E-print Network

We present a method for direct non-optical quantification of dry mass, dry density and water mass of single living cells in suspension. Dry mass and dry density are obtained simultaneously by measuring a cell’s buoyant ...

Cermak, Nathan

320

50 CFR 27.33 - Water skiing.  

Code of Federal Regulations, 2010 CFR

...Guard approved ski belts, life jackets or buoyant vests. (e) Water skiing is prohibited within 300 feet of harbors, swimming beaches, and mooring areas, and within 100 feet of any designated swimming...

2010-10-01

321

46 CFR 160.050-3 - Materials.  

Code of Federal Regulations, 2011 CFR

...other suitable buoyant type synthetic material having a minimum breaking strength of 1,350 pounds. (d) Beckets...saran or other suitable synthetic material having a minimum breaking strength of 585 pounds. In addition,...

2011-10-01

322

46 CFR 160.050-3 - Materials.  

Code of Federal Regulations, 2013 CFR

...other suitable buoyant type synthetic material having a minimum breaking strength of 1,350 pounds. (d) Beckets...saran or other suitable synthetic material having a minimum breaking strength of 585 pounds. In addition,...

2013-10-01

323

46 CFR 160.050-3 - Materials.  

Code of Federal Regulations, 2012 CFR

...other suitable buoyant type synthetic material having a minimum breaking strength of 1,350 pounds. (d) Beckets...saran or other suitable synthetic material having a minimum breaking strength of 585 pounds. In addition,...

2012-10-01

324

46 CFR 176.402 - Initial inspection for certification.  

Code of Federal Regulations, 2011 CFR

...detecting and extinguishing equipment, pollution prevention equipment, and all other equipment... (1) The installation of each rescue boat, liferaft, inflatable buoyant apparatus... (2) The operation of each rescue boat and survival craft launching...

2011-10-01

325

46 CFR 115.402 - Initial inspection for certification.  

Code of Federal Regulations, 2010 CFR

...detecting and extinguishing equipment, pollution prevention equipment, and all other equipment... (1) The installation of each rescue boat, liferaft, inflatable buoyant apparatus... (2) The operation of each rescue boat and survival craft launching...

2010-10-01

326

46 CFR 176.402 - Initial inspection for certification.  

Code of Federal Regulations, 2010 CFR

...detecting and extinguishing equipment, pollution prevention equipment, and all other equipment... (1) The installation of each rescue boat, liferaft, inflatable buoyant apparatus... (2) The operation of each rescue boat and survival craft launching...

2010-10-01

327

46 CFR 115.402 - Initial inspection for certification.  

Code of Federal Regulations, 2011 CFR

...detecting and extinguishing equipment, pollution prevention equipment, and all other equipment... (1) The installation of each rescue boat, liferaft, inflatable buoyant apparatus... (2) The operation of each rescue boat and survival craft launching...

2011-10-01

328

International Journal of Greenhouse Gas Control 7 (2012) 153167 Contents lists available at SciVerse ScienceDirect  

E-print Network

literature. The Eau Claire Formation is the caprock overlying the Mount Simon sandstone formation, one to prevent the buoyant CO2 from escaping to shallow drinking water aquifers or the ground surface. Here we

Zhu, Chen

329

Future welfare, prosperity, and sustainability of the human enterprise rely on science-informed decisions about our social systems and the environment.  

E-print Network

environmental fluid mechanics, hydrology, environmental health, aquatic and atmospheric chemistry included bubble plumes used for reservoir destratification, plumes of buoyant liquid CO2 droplets or dense to Water Quality Control Research Interests Contaminant fate and transport Water quality modeling Jets

Polz, Martin

330

Resistance of red mangrove ( Rhizophora mangle L.) seedlings to deflection and extraction  

Microsoft Academic Search

Red mangrove (Rhizhophora mangle L.) is the dominant tree species in the intertidal zone of ecosystems on the Atlantic shores of the Caribbean and tropical\\u000a western Atlantic. The propagules of this species are initially buoyant, becoming negatively buoyant before rooting in a variety\\u000a of substrates. After establishment, these seedlings form aerial roots, leading to communities of plants with complex networks

Sophie D. Boizard; Stephen J. Mitchell

2011-01-01

331

Buoyancy Bulls-Eye  

NSDL National Science Digital Library

In this hands-on activity, learners will construct a scuba diver that can float in order to explore how sea creatures stay neutrally buoyant in the ocean and to see what kinds of forces might be influencing their buoyancy. By adding materials such as balloons, rubber bands, toothpicks, pennies, etc. to their figure, they will try to make it neutrally buoyant in a bucket of water. This lesson plan includes discussion questions, key vocabulary, and is standards-based.

Sciences, California A.

2008-01-01

332

Investigation of the free flow electrophoretic process. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

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.

Weiss, R. A.; Lanham, J. W.; Richman, D. W.; Walker, C. D.

1979-01-01

333

The stability of buoyancy-driven coastal currents  

Microsoft Academic Search

Griffiths, R.W. and Linden, P.F., 1981. The stability of buoyancy-driven coastal currents. Dyn. Atmos. Oceans, 5: 281--306. Buoyancy-driven boundary currents were generated in the laboratory by releasing buoyant fluid from a source adjacent to a vertical boundary in a rotating container. The boundary removed the Coriolis force parallel to it, allowing the buoyant fluid to spread in a current along

R. W. GRIFFITHS; P. F. LINDEN

1981-01-01

334

Floating rings in vertical soap films : capillary driven bidimensional buoyancy  

E-print Network

The present study aims to investigate the motion of buoyant rings in vertical soap films. Thickness differences and related bi-dimensional densities are considered as the motor leading to bi-dimensional buoyancy. We show how this effect can be re-interpreted thanks to surface tension profiles in soap films. We propose a model involving surface tension profiles in order to describe the motion of buoyant particles in vertical soap films, and compare it to experimental data.

Adami, N

2013-01-01

335

Influence of Richardson number on the ejection of a miscible contaminant from a rectangular cavity by an incoming fully turbulent overflow  

Microsoft Academic Search

The 3D flow past a rectangular shallow cavity is investigated using LES. The flow upstream the cavity is fully turbulent. The unsteady purging mechanism corresponding to ejection of a neutrally buoyant (Richardson number, Ri=0.0) and of a dense miscible contaminant (Ri=0.2) introduced instantaneously inside the cavity is studied. In the non-buoyant case it is shown that along with the engulfment

George Constantinescu; Kyoungsik Chang; Seung-O. Park

2005-01-01

336

Mass and density measurements of live and dead Gram-negative and Gram-positive bacterial populations.  

PubMed

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. PMID:24705320

Lewis, Christina L; Craig, Caelli C; Senecal, Andre G

2014-06-01

337

LTA structures and materials technology  

NASA Technical Reports Server (NTRS)

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.

Mayer, N. J.

1975-01-01

338

Dynamics of anchored flux tubes in the convection zone. I - Details of the model  

NASA Astrophysics Data System (ADS)

A model for the emergence of buoyant segments of magnetic flux tubes whose ends are still anchored in the stable layers below the convection zone is developed. This model is based on the thin flux tube approximation of Spruit. Several specific examples of buoyant flux tube evolution computed with the model are described. In particular, attention is given to an example of a flux tube which results in upflows as it emerges, in contrast to the downflows generally believed to accompany the Parker instability.

Chou, Dean-Yi; Fisher, George H.

1989-06-01

339

46 CFR 160.047-2 - Model.  

Code of Federal Regulations, 2012 CFR

...Specification for a Buoyant Vest, Kapok or Fibrous Glass, Adult and Child § 160.047-2 Model... (b) Model AF-1, adult, fibrous glass (for persons weighing more than 90 pounds...Model CFM-1, child medium, fibrous glass (for children weighing from 50 to 90...

2012-10-01

340

Influence of an external radiant flux on a 15-cm-diameter kerosene pool fire  

Microsoft Academic Search

In this paper an experimental study is presented of the influence of an externally applied thermal radiant flux on the evaporation, or burning rate of a 15-cm-diameter kerosene pool fire, and on the structure of the buoyant flame developed over the liquid fuel surface. The results show that the burning rate increases with the external radiation, but as the radiant

X. L. Zhang; J. P. Vantelon; P. Joulain; A. C. Fernandez-Pello

1991-01-01

341

Lateral Migration and Rotational Motion of Elliptic Particles in Planar Poiseuille Flow  

NASA Technical Reports Server (NTRS)

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.

Qi, Dewei; Luo, Li-Shi; Aravamuthan, Raja; Strieder, William; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

342

Revisiting Carbon Flux Through the Ocean's Twilight Zone  

Microsoft Academic Search

The oceanic biological pump drives sequestration of carbon dioxide in the deep sea via sinking particles. Rapid biological consumption and remineralization of carbon in the ``twilight zone'' (depths between the euphotic zone and 1000 meters) reduce the efficiency of sequestration. By using neutrally buoyant sediment traps to sample this chronically understudied realm, we measured a transfer efficiency of sinking particulate

Ken O. Buesseler; Carl H. Lamborg; Philip W. Boyd; Phoebe J. Lam; Thomas W. Trull; Robert R. Bidigare; James K. B. Bishop; Karen L. Casciotti; Frank Dehairs; Marc Elskens; Makio Honda; David M. Karl; David A. Siegel; Mary W. Silver; Deborah K. Steinberg; Jim Valdes; Benjamin Van Mooy; Stephanie Wilson

2007-01-01

343

Influence of the Fragmentation Process on the Eruptive Dynamics of Vulcanian Eruptions: an Experimental Approach  

Microsoft Academic Search

During volcanic eruptions, the ejection velocity of the gas-pyroclast mixture is one of the main parameters that control the behavior of the eruptive column near the vent. Together with other factors such as density of the mixture, temperature and vent geometry, it determines whether a buoyant plume can develop or if the column will collapse leading to a pyroclastic flow.

M. A. Alatorre-Ibarguengoitia; A. Arciniega-Ceballos; D. B. Dingwell; D. Richard; B. Scheu; U. Kueppers; H. Delgado-Granados; M. Navarrete Montesinos

2009-01-01

344

Trends and Challenges in Islamic Finance  

Microsoft Academic Search

The paper first discusses the current trends in Islamic finance, which has become mainstream with currently more than US$800 billion of assets worldwide and a buoyant market for sukuk bonds. However, this exorbitant growth raises many challenges, particularly in the areas of banking, capital markets and regulation. Thus, the paper then considers these challenges, notably the economic and legal bottlenecks

Heiko Hesse; Andreas A. Jobst

2008-01-01

345

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

Code of Federal Regulations, 2010 CFR

...or lifefloats must not be stowed in more than four tiers and, when stowed in tiers, the separate units must be kept apart by spacers; and (E) The group of buoyant apparatus or lifefloats must be stowed to prevent shifting with easily detached...

2010-10-01

346

Measurement of the inertial lift on a moving sphere in contact with a plane wall in a shear flow  

Microsoft Academic Search

The translational and rotational velocities of a positively buoyant sphere suspended in a parallel plate device are measured, and related to the inertial lift of the sphere from the upper plate. The experimental results obtained agree well with the corrected theoretical predictions of Krishnan and Leighton [Phys. Fluids 7, 11 (1995)]. The motion of the sphere principally depends on the

Michael R. King

1997-01-01

347

Oceanic Hotspots  

Microsoft Academic Search

The Wilson-Morgan hypothesis that fixed mantle plumes rising from deep in Earth's mantle give rise to linear island and seamount chains like Hawaii has been a leading idea in planetary geodynamics for many decades. However, the notion that these ascending columns of buoyant mantle material are fixed relative to each other or to a fixed reference frame has been questioned

Rodey Batiza

2004-01-01

348

Simulation of Flux Emergence from the Convection Zone to the Corona  

Microsoft Academic Search

Here, we present numerical simulations of magnetic flux buoyantly rising from a granular convection zone into the low corona. We study the complex interaction of the magnetic field with the turbulent plasma. The model includes the radiative loss terms, non-ideal equations of state, and empirical corona heating. We find that the convection plays a crucial role in shaping the morphology

Fang Fang; Ward Manchester; William P. Abbett; Bart van der Holst

2010-01-01

349

SIMULATION OF FLUX EMERGENCE FROM THE CONVECTION ZONE TO THE CORONA  

Microsoft Academic Search

Here, we present numerical simulations of magnetic flux buoyantly rising from a granular convection zone into the low corona. We study the complex interaction of the magnetic field with the turbulent plasma. The model includes the radiative loss terms, non-ideal equations of state, and empirical corona heating. We find that the convection plays a crucial role in shaping the morphology

Fang Fang; Ward Manchester IV; Bart Van der Holst; William P. Abbett

2010-01-01

350

Reducing Fume Emission from Smelting Vessels Using Combined Cfd and Engineering Modelling  

Microsoft Academic Search

Capture of fugitive emissions from charge ports, tap holes and many other openings in mineral processing and smelting vessels poses a significant environmental and hygiene problem. While fume and hygiene hoods are often used the highly buoyant nature of the fume combined with complex geometries makes their design with traditional engineering tools difficult. A computational fluid dynamics (CFD) model has

PJ Witt; CB Solnordal; A Manzoori; S Finn; J Pluta; H Namavari; E Niknejad; M Davari

351

Mon. Feb. 16, 2004. | Updated at 05:56 PM Home GTA Business Waymoresports A&E  

E-print Network

the little microscopic marbles every day. With microspheres, boat bumpers are more buoyant and cosmetics jutting out of a sphere to cause traffic jams. Cosmetics companies use ceramic microspheres in liquid:57 AM Tiny bubbles, sticky solutions What do Post-it notes have in common with cosmetics, pills

Braun, Paul

352

Ocean Dynamics DOI 10.1007/s10236-011-0475-7  

E-print Network

in the fresh- water discharge and the density difference between buoyant inflow and more saline Irish Sea water thermohaline front. A statistically based water mass classification technique is used to locate the front of the plume, a bottom-advected front develops. Over the summer, when warm river water provides additional

Polton, Jeff

353

Fractionation of Eastern Equine Encephalitis Virus by Density Gradient Centrifugation in CsCl.  

National Technical Information Service (NTIS)

When partially purified Eastern equine encephalitis (EEE) virus was centrifuged to equilibrium in CsCl, three virus specific bands were observed. A hemagglutinin was detected at a buoyant density of 1.18 g/cu cm. Infectious EEE virus banded in two positio...

H. G. Aaslestad, E. J. Hoffman, A. Brown

1968-01-01

354

The fate of river discharge on the continental shelf 1. Modeling the river plume and the inner shelf coastal current  

Microsoft Academic Search

We study the development and evolution of buoyant river plumes on the continental shelf. Our calculations are based on three-dimensional numerical simulations, where the river runoff is introduced as a volume of zero salinity water in the continuity equation and mixing is provided by the model's turbulence closure scheme and wind forcing. In the absence of wind forcing the modeled

Vassiliki H. Kourafalou; Lie-Yauw Oey; John D. Wang; Thomas N. Lee

1996-01-01

355

How Stable Is Stable?  

ERIC Educational Resources Information Center

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)

Baehr, Marie

1994-01-01

356

Introduction Advantages/disadvantages of an upright posture  

E-print Network

flexural stiffness, or (2) by being buoyant. The flexural stiffness (EI) of a structure is a measure, measured as the elastic modulus (E) (Wainwright et al., 1976). Buoyancy maintains an organism in an upright and flexural stiffness maintain benthic organisms in upright positions, these mechanisms (an upward restoring

Stewart, Hannah Louise

357

SCOOP--An Improved Submarine Cable Recovery System  

Microsoft Academic Search

For more than twenty years, acoustically controlled, buoyant subsurface arrays have been utilized by research institutions and industry for mooring, location, and retrieval of oceanographic instruments. Submarine telecommunications cable laying and repair operations typically involve location and retrieval of free cable ends left on the seafloor. In deep water areas, conventional methods for cable-end location and recovery included the use

G. Rich; J. Ewald; C. Jeffcoat; R. Weller

1984-01-01

358

Buoyancy characteristics of the bloater (Coregonus hoyi) in relation to patterns of vertical migration and acoustic backscattering  

USGS Publications Warehouse

Acoustic studies in Lake Michigan found that bloaters (Coregonus hoyi) were less reflective per size than the other major pelagic species. This difference in in situ acoustic backscattering could indicate that the deep-water bloaters have compressed swimbladders for much of their vertical range with related implications on buoyancy. To test this hypothesis, the buoyancy characteristics of bloaters were determined with fish placed in a cage that was lowered to bottom and monitored with an underwater camera. We found bloaters were positively buoyant near surface, neutrally buoyant at intermediate strata, and negatively buoyant near bottom. This pattern was consistent for the range of depths bloaters occur. The depth of neutral buoyancy (near the 50-n strata) corresponds with the maximum extent of vertical migration for bloaters observed in acoustic surveys. Fish below this depth would be negatively buoyant which supports our contention that bloaters deeper in the water column have compressed swimbladders. Understanding the buoyancy characteristics of pelagic fishes will help to predict the effects of vertical migration on target strength measurement and confirms the use of acoustics as a tool to identify and quantify the ecological phenomenon of vertical migration.

Fleischer, Guy W.; TeWinkel, Leslie M.

1998-01-01

359

Early Adult Antecedents of Life Satisfaction at Age 70.  

ERIC Educational Resources Information Center

Examined association between Life Satisfaction Ratings at age 70 and cognitive, personality, interpersonal, and family characteristics at age 30. Predictive characteristics of life satisfaction at 70 were, for women, a buoyant, responsive attitude toward life; for men, emotional and physical health. (Author/RC)

Mussen, Paul; And Others

1982-01-01

360

Economic pipelaying via guide-roping  

Microsoft Academic Search

The underwater pipeline laying method developed by C. G. Doris consists of towing long sections of pipe a few meters above the seabed. Buoyant units and chains fitted on the pipe restrict the forces on the pipe during transportation. Required surface facilities are cheaper than the classical pipelaying barges. It is possible to install pipe sections over 10 km long

G. Chevaux; C. G. Doris

1978-01-01

361

FLUID MODELING SIMULATION OF STACK-TIP DOWNWASH  

EPA Science Inventory

Downwash of neutrally buoyant effluent on the immediate lee side of a circular stack was modeled using a wind tunnel simulation. oth subcritical and supercritical turbulent flows were simulated, where the criticality refers to Reynolds numbers below and above the critical Reynold...

362

Hydrothermal Processes  

Microsoft Academic Search

What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly

C. R. German; K. L. von Damm

2003-01-01

363

46 CFR 160.055-5 - Construction-standard life preservers.  

Code of Federal Regulations, 2010 CFR

...and adjustable body strap. (1...so as to have dimensions after coating...and Sheet 2 for child size. The reinforcing...the foam buoyant body before coating...and adjustable body strap. (1...have finished dimensions in accordance...Sheet 4, for child size. One...

2010-10-01

364

46 CFR 160.055-5 - Construction-standard life preservers.  

Code of Federal Regulations, 2012 CFR

...and adjustable body strap. (1...so as to have dimensions after coating...and Sheet 2 for child size. The reinforcing...the foam buoyant body before coating...and adjustable body strap. (1...have finished dimensions in accordance...Sheet 4, for child size. One...

2012-10-01

365

46 CFR 160.055-5 - Construction-standard life preservers.  

Code of Federal Regulations, 2013 CFR

...and adjustable body strap. (1...so as to have dimensions after coating...and Sheet 2 for child size. The reinforcing...the foam buoyant body before coating...and adjustable body strap. (1...have finished dimensions in accordance...Sheet 4, for child size. One...

2013-10-01

366

46 CFR 160.055-5 - Construction-standard life preservers.  

Code of Federal Regulations, 2011 CFR

...and adjustable body strap. (1...so as to have dimensions after coating...and Sheet 2 for child size. The reinforcing...the foam buoyant body before coating...and adjustable body strap. (1...have finished dimensions in accordance...Sheet 4, for child size. One...

2011-10-01

367

Applicability of Boussinesq approximation in a turbulent fluid with constant properties  

Microsoft Academic Search

The equations of motion describing buoyant fluids are often simplified using a set of approximations proposed by J. Boussinesq one century ago. To resume, they consist in assuming constant fluid properties, incompressibility and conservation of calories during heat transport. Assuming fulfilment of the first requirement (constant fluid properties), we derive a set of 4 criteria for assessing the validity of

Philippe-Emmanuel P.-E. Roche

2007-01-01

368

46 CFR 160.027-2 - Type.  

Code of Federal Regulations, 2010 CFR

(a) Each life float must meet the requirements in subpart 160.010 of this chapter for a peripheral body type buoyant apparatus designed so that persons supported are only partially immersed (180 N (40 lb.) of buoyancy per person required). (b)...

2010-10-01

369

Role of the Laboratory: Static Equilibrium  

NSDL National Science Digital Library

This activity from the PTRA Manual "The Role of the Laboratory in Teaching Introductory Physics" is a variation of the typical static laboratory activity, and includes a method of measuring buoyant force. See article "Static Equilibrium", by Jim Nelson in the December, 1985 issue of The Science Teacher.

Nelson, Jim; Nelson, Jane

2006-06-18

370

Astronomy & Astrophysics manuscript no. paper c ESO 2014 April 22, 2014  

E-print Network

or vanishing rotation, the growth rate of NEMPI increases with increasing gravity, but there is a correction term for strong gravity and large turbulent magnetic diffusivity. Conclusions. Magnetic flux (1955) interpreted the emergence of sunspots as the result of magnetically buoyant flux tubes at a depth

Brandenburg, Axel

371

arXiv:1401.6107v1[astro-ph.SR]23Jan2014 Astronomy & Astrophysics manuscript no. paper c ESO 2014  

E-print Network

, for weak or vanishing rotation, the growth rate of NEMPI increases with increasing gravity, but there is a correction term for strong gravity and large turbulent magnetic diffusivity. Conclusions. Magnetic flux the emergence of sunspots as the result of magnetically buoyant flux tubes at a depth of some 20 Mm

Brandenburg, Axel

372

Mon. Not. R. Astron. Soc. 000, 000000 (0000) Printed 16 April 2014 (MN LATEX style file v2.2) Properties of p -and f-modes in hydromagnetic turbulence  

E-print Network

. (2010). This technique uses sound waves (p -modes) and to some extent surface gravity waves (f-modes), but the pres- ence of magnetic fields gives rise to magneto-acoustic and magneto-gravity waves, whose restoring range of origins. The most popular one is the buoyant rise and emergence of flux tubes deeply rooted

Brandenburg, Axel

373

On a small-scale roughness of the core^mantle boundary C. Narteau a  

E-print Network

of the crystalline man- tle surrounded by liquid can be loosened, £oat at the top of the core, and go on dissolving of the core £uid is buoyant and tends to £oat upward near the CMB. Two competing processes take place

Narteau, Clément

374

46 CFR 24.10-1 - Definitions.  

Code of Federal Regulations, 2010 CFR

...sheer. This term includes a boat equipped with a detachable motor...or (3) A member of the crew engaged in the business of the...buoyant apparatus, or small boat. Vessel, as used in this...That is chartered with the crew provided or specified by...

2010-10-01

375

46 CFR 24.10-1 - Definitions.  

Code of Federal Regulations, 2011 CFR

...sheer. This term includes a boat equipped with a detachable motor...or (3) A member of the crew engaged in the business of the...buoyant apparatus, or small boat. Vessel, as used in this...That is chartered with the crew provided or specified by...

2011-10-01

376

46 CFR 131.340 - Recommended placard for emergency instructions.  

Code of Federal Regulations, 2011 CFR

...inflatable) buoyant apparatus, and boats—for launching. (b) “Man... (3) Launch the rescue boat and maneuver it to pick up...the person. (4) Have a crew member put on an immersion...safety line made fast to the crew member, and have the...

2011-10-01

377

46 CFR 131.340 - Recommended placard for emergency instructions.  

Code of Federal Regulations, 2010 CFR

...inflatable) buoyant apparatus, and boats—for launching. (b) “Man... (3) Launch the rescue boat and maneuver it to pick up...the person. (4) Have a crew member put on an immersion...safety line made fast to the crew member, and have the...

2010-10-01

378

Rapid formation of hyperpycnal sediment gravity currents offshore of a semi-arid California river  

Microsoft Academic Search

Observations of sediment dispersal from the Santa Clara River of southern California during two moderately sized river discharge events suggest that river sediment rapidly formed a negatively buoyant (hyperpycnal) bottom plume along the seabed within hours of peak discharge. An array of acoustic and optical sensors were placed at three stations 1km from the Santa Clara River mouth in 10-m

Jonathan A. Warrick; Jingping Xu; Marlene A. Noble; Homa J. Lee

2008-01-01

379

An Adjoint Sensitivity Study of Buoyancy-and Wind-Driven Circulation on the New Jersey Inner Shelf  

E-print Network

York Bight circulation for three idealized situations: an unforced buoyant river plume, and upwelling). These studies indicate that tides, river runoff, and air­sea exchanges all exert influence with no single and Garvine 1998) and bathymetry variations (Chant et al. 2004; Garvine 2004; Kohut et al. 2004) also affect

Wilkin, John

380

IN SITU TREATMENT OF HAZARDOUS MATERIAL SPILLS IN FLOWING STREAMS  

EPA Science Inventory

Two methods of applying activated carbon adsorption treatment to flowing streams were evaluated under comparable conditions. The first involved subsurface introduction of buoyant carbon into the water column followed by the floating of the carbon to the surface and subsequent rem...

381

Modeling cooling water discharges from the Burrard Generating Station, BC Canada  

Microsoft Academic Search

A three-dimensional numerical model was applied to examine the impact of the Burrard Generating Station cooling water on the circulation patterns and thermal regime in the receiving water of Port Moody Arm. A key aspect of this study involved properly incorporating the submerged cooling water buoyant jet into the 3D model. To overcome the scale and interface barriers between the

J. Jiang; D. B. Fissel; D. D. Lemon; D. Topham

2002-01-01

382

Modulation of homogeneous turbulence seeded with finite size bubbles or particles , S. Dong a,1  

E-print Network

Modulation of homogeneous turbulence seeded with finite size bubbles or particles K. Yeo a , S or bubbles is inves- tigated in a series of numerical simulations, using the force-coupling method on the modulation of the turbulence due to massless bubbles, neutrally buoyant particles and inertial particles

Dong, Suchuan "Steven"

383

Spherical cap bubbles with a toroidal bubbly wake J. R. Landel, C. Cossu, and C. P. Caulfield  

E-print Network

speed of large buoyant bubbles is a fundamental fluid mechanics problem relevant to a number of applications ranging from carbon sequestration technology to chemical engineering or astrophysics. Single large�3 to chemical engineering4�6 or carbon sequestration technology. For instance, in problems related to CO2

Boyer, Edmond

384

CORMIX1: AN EXPERT SYSTEM FOR MIXING ZONE ANALYSIS OF TOXIC AND CONVENTIONAL, SINGLE PORT AQUATIC DISCHARGES  

EPA Science Inventory

An expert system, CORMIX1, was developed to predict the dilution and trajectory of a single buoyant discharge into an unstratified aquatic environment with and without crossflow. The system uses knowledge and inference rules obtained from hydrodynamic experts to classify and pred...

385

The influence of mantle melting on the evolution of Mars  

Microsoft Academic Search

We present a parameterized convection model of Mars by incorporating a new heat-flow scaling law for stagnant-lid convection, to better understand how the evolution of Mars may be affected by mantle melting. Melting in the mantle during convection leads to the formation of a compositionally buoyant lithosphere, which may also be intrinsically more viscous by dehydration. The consequences of these

Abigail A. Fraeman; Jun Korenaga

2010-01-01

386

The western Arctic boundary current at 1521W: Structure, variability, and transport  

E-print Network

Shelf-edge dynamics Boundary currents Volume transport Pacific water Atlantic water a b s t r a c t From measurements, with emphasis on the Pacific water component of the current. The mean flow is characterized it becomes surface-intensified as it advects buoyant Alaskan Coastal water. In fall and winter the current

Pickart, Robert S.

387

Sky Floater Challenge  

NSDL National Science Digital Library

In this design challenge activity, learners make a balloon hover at eye level for five seconds, and then make it move by creating air currents. The activity guide contains information for Educators on how to best facilitate the challenge as well as key vocabulary (buoyancy, neutrally buoyant, Newton's 1st Law, etc.). Two associated videos available for download help reinforce these concepts.

Wgbh

2009-01-01

388

Air flow and particle control with different ventilation systems in a classroom  

Microsoft Academic Search

Most ventilation and air conditioning systems are designed without much concern about how settling particles behave in ventilation air flows. For displacement ventilation systems, designers normally assume that all pollutants follow the buoyant air flow into an upper zone, where they are evacuated. This is, however, not always true. Previous studies show that high concentrations of settling respirable particles can

Sture Holmberg; Qingyan Chen

2003-01-01

389

Contamination control in semiconductor industry using laminar barrier inerting technology  

Microsoft Academic Search

Laminar Barrier Inerting is a new and effective method of preventing air infiltration into semiconductor process equipment. Air infiltration during loading and unloading is a major source of contamination within semiconductor process furnaces. During these steps, cooler clean room air can replace hot process nitrogen due to buoyant forces. Many fabrication processes are quite sensitive to oxygen and moisture resulting

E. Quilantang; A. Sharif; A. Hosein; T. Yokum; R. Cartwright

1994-01-01

390

Numerical modeling of ocean-ice interactions under Pine Island Bay's ice shelf  

Microsoft Academic Search

A two-dimensional numerical model is used to simulate the dynamics of buoyant, meltwater-rich plumes flowing beneath the ice shelf occupying much of Pine Island Bay, West Antarctica. Recent studies have shown that this ice shelf, along with all others fringing the Amundsen Sea, is thinning rapidly. In the model, both the Coriolis effect and subshelf topography are important in controlling

Antony J. Payne; Paul R. Holland; Andrew P. Shepherd; Ian C. Rutt; Adrian Jenkins; Ian Joughin

2007-01-01

391

VOLUME 132 APRIL 2004M O N T H L Y W E A T H E R R E V I E W 2004 American Meteorological Society 853  

E-print Network

science has its roots in the so-called Law of Archi- medes, taught in basic physics courses as the ratio of the specific weight of the fluid to the specific weight of the object; or, in another manner, by the weight of the fluid displaced minus the weight of the object. 2. (Or buoyant force, buoyancy force; also

Doswell III, Charles A.

392

Buoyancy effects on the temperature field in downward spreading flames  

NASA Technical Reports Server (NTRS)

It is shown that flames which spread vertically down thermally thin fuels at the same Damkoehler number, and therefore have the same dimensionless spread rate, also have the same dimensionless temperature fields irrespective of differences in physical size. The Frey and Tien (1976) effects of pressure on flame size are due to the effects of pressure on the character of the induced buoyant flow.

Altenkirch, R. A.; Winchester, D. C.; Eichhorn, R.

1982-01-01

393

Proceedings of the Combustion Institute, Volume 29, 2002/pp. 16631670 CHEMILUMINESCENT OH* AND CH* FLAME STRUCTURE AND  

E-print Network

uncertainty in the flame structure caused by the flow field. For diffusion flames, a suitable configuration* AND CH* FLAME STRUCTURE AND AERODYNAMIC SCALING OF WEAKLY BUOYANT, NEARLY SPHERICAL DIFFUSION FLAMES S. W with inverse diffusion flames of small density difference with their surrounding ambient to study low Grashof

Tse, Stephen D.

394

Abstract Hoodoo Mountain volcano (HMV) is a Qua-ternary phonolitic volcano situated on the north side of  

E-print Network

-crustal pressures. The attendant changes in magma density related to differentiation permitted the continued buoyant ascent and eruption of phonolitic magmas derived from basaltic parental magmas that stalled in the crust. In this environment, the slight chang- es in lithostatic pressure accompanying fluctuations in Cordilleran ice sheets

Russell, Kelly

395

The taphonomic attributes of a Late Cretaceous plesiosaur skeleton from New Zealand  

Microsoft Academic Search

The pre-burial history of a partial elasmosaurid plesiosaur skeleton is reconstructed from analysis of the distribution and modification of bones preserved in a calcareous concretionary mass. The specimen lacks the skull, cervical vertebrae, left limb bones and some girdle elements, but the remaining bones are interpreted to have been deposited on the sea floor from a semi-buoyant carcass and their

Kelly M. Barnes; Norton Hiller

2010-01-01

396

A recombinant particulate antigen of Japanese encephalitis virus produced in stably-transformed cells is an effective noninfectious antigen and subunit immunogen  

Microsoft Academic Search

A COS-1 cell line, stably transformed by a plasmid encoding the premembrane and envelope glycoproteins of Japanese encephalitis virus, produced a noninfectious recombinant antigen expressed as extracellular particles. Extracellular particles purified by equilibrium density centrifugation in sucrose gradients followed by electron microscopy were characterized as spherical particles with an average diameter of approximately 30 nm and a buoyant density of

Ann R Hunt; C. Bruce Cropp; Gwong-Jen J Chang

2001-01-01

397

A coastal current in winter: 2. Wind forcing and cooling of a coastal current east of Cape Cod  

Microsoft Academic Search

The combined effect of cooling and wind-driven buoyancy flux (WDBF) on a buoyant coastal current east of Cape Cod is investigated using observations and process-oriented numerical modeling. Theoretical considerations show that with the moderately strong surface density gradients observed in the Outer Cape Cod Coastal Current, WDBF can substantially exceed the buoyancy loss due to cooling, especially during intense winter

Andrey Y. Shcherbina; Glen G. Gawarkiewicz

2008-01-01

398

Resistive and propulsive forces associated with jet propulsion have been investigated in scallops (Trueman, 1975;  

E-print Network

-first orientation) varied from 9.0 to 15.3cms-1. At low speeds, negatively buoyant brief squid generated lift and/or improved stability by positioning the mantle and arms at high angles of attack, directing high-speed jets downwards (angles >50°) and using fin activity. To reduce drag at high speeds, the squid decreased angles

Hynes, Wayne L.

399

Aquatic Mammals 2002, 28.2, 103-112 Fur does not fly, it floats: buoyancy of pelage in semi-aquatic  

E-print Network

, Ornithorhynchus anatinus).We determined buoyancy hydrostatically, measured hair density on histological skin samples, and hair length and diameter. Buoyancy was posi- tively correlated with hair density in terrestrial mammals. Enhydra displayed the greatest hair density (1188.8 hairs/mm2j with a buoyant force of 0

Fish, Frank

400

CASC&ENJournalsACSLog In Serving The Chemical, Life Sciences & Laboratory Worlds  

E-print Network

resonance imaging is the largest single use for helium.a Includes weather balloons, blimps, party balloons,500 L of helium. Credit: Dean Olson, U of Ill., Urbana-Champaign [+]Enlarge BUOYANT MARKETS Magnetic > Helium Shortage Affecting Instrument Users To Extend Into 2013 Volume 90 Issue 29 | pp. 32-34 Issue Date

Ha, Taekjip

401

Thermal sensing of fireball plumes  

Microsoft Academic Search

An algorithm has been developed to reconstruct the internal temperature distribution within a rising buoyant thermal from measurements of the radiances by an infrared imaging camera. The technique is applied to detonation of a stoichiometric mixture of methane and oxygen contained in a three-meter diameter mylar balloon. The temperature-time histories of the evolving fireball showed torus formation, followed by rapid

Reza Toossi

1991-01-01

402

Buoyancy control of four species of eleotrid fishes during aquatic surface respiration  

Microsoft Academic Search

Four species of Australian Eleotridae from hypoxic habitats were examined in the laboratory to study buoyancy control in hypoxic water (2 can be reabsorbed from the swimbladder (reducing buoyancy) at a time when additional lift may be required to perform ASR. Three species were negatively buoyant and initially performed ASR while resting on the bottom in shallow water. After 24

John H. Gee

1986-01-01

403

Buoyancy function of the enlarged fluid-filled cranium in the deep-sea ophidiid fish Acanthonus armatus  

Microsoft Academic Search

Acanthonus armatus Günther (family Ophidiidae) is a slightly negatively buoyant (mean weight in surface seawater =0.58% of air weight) benthopelagic fish without a swimbladder that has reduced tissues and components (muscle, bone, brain, gills, lipids) and a massive head. This species has an enlarged cranial cavity (10% of head volume) filled, except for the very small brain, with a low-density

M. H. Horn; P. W. Grimes; C. F. Phleger; L. L. McClanahan

1978-01-01

404

Energetics of the Ocean's Infrasonic Sound Field  

Microsoft Academic Search

Simultaneous measurements of infrasonic (0.5-20 Hz) particle velocity and pressure made by the Marine Physical Laboratory's freely drifting, independent, and neutrally buoyant Swallow floats are analyzed in terms of the energetics of acoustic fields. The theory of acoustic field energetics is presented and compared to standard data analysis techniques. The properties of the potential and kinetic energy density spectra, and

Gerald Lynden D'Spain

1990-01-01

405

Repetitive DNA sequences in Drosophila  

Microsoft Academic Search

The satellite DNAs of Drosophila melanogaster and D. virilis have been examined by isopycnic centrifugation, thermal denaturation, and in situ molecular hybridization. The satellites melt over a narrow temperature range, reassociate rapidly after denaturation, and separate into strands of differing buoyant density in alkaline CsCl. In D. virilis and D. melanogaster the satellites constitute respectively 41% and 8% of the

Joseph G. Gall; Edward H. Cohen; Mary Lake Polan

1971-01-01

406

46 CFR 160.052-5 - Construction-standard vests.  

Code of Federal Regulations, 2013 CFR

...Buoyant Vest, Unicellular Plastic Foam, Adult and Child § 160.052-5 Construction...Dwg. No. 160.052-1, Sheet 1 for adult size, and Sheets 2 and 3 for child...piece of the envelope in way of the strap attachments as shown by the drawings. (c)...

2013-10-01

407

46 CFR 160.052-5 - Construction-standard vests.  

Code of Federal Regulations, 2010 CFR

...Buoyant Vest, Unicellular Plastic Foam, Adult and Child § 160.052-5 Construction...Dwg. No. 160.052-1, Sheet 1 for adult size, and Sheets 2 and 3 for child...piece of the envelope in way of the strap attachments as shown by the drawings. (c)...

2010-10-01

408

46 CFR 160.052-5 - Construction-standard vests.  

Code of Federal Regulations, 2012 CFR

...Buoyant Vest, Unicellular Plastic Foam, Adult and Child § 160.052-5 Construction...Dwg. No. 160.052-1, Sheet 1 for adult size, and Sheets 2 and 3 for child...piece of the envelope in way of the strap attachments as shown by the drawings. (c)...

2012-10-01

409

46 CFR 160.052-5 - Construction-standard vests.  

Code of Federal Regulations, 2011 CFR

...Buoyant Vest, Unicellular Plastic Foam, Adult and Child § 160.052-5 Construction...Dwg. No. 160.052-1, Sheet 1 for adult size, and Sheets 2 and 3 for child...piece of the envelope in way of the strap attachments as shown by the drawings. (c)...

2011-10-01

410

Venus Atmospheric Maneuverable Platform (VAMP)  

NASA Astrophysics Data System (ADS)

VAMP is a long lived, semi-buoyant, atmospheric “rover” that deploys in orbit, enters the Venus atmosphere and flies in the Venus atmosphere between 55 and 70 km for up to one year as a platform to address VEXAG goals I.A, I.B, and I.C.

Polidan, R.; Lee, G.; Sokol, D.; Griffin, K.; Bolisay, L.

2014-05-01

411

A Comment on Non-Archimedean Character of Quantum Buoyancy  

E-print Network

In a gedankenexperiment about the generalized second law (GSL) of black hole thermodynamics, the buoyant force by black hole atmosphere (the acceleration radiation) plays an important role, and then it is significant to understand the nature of the buoyant force. Recently, Bekenstein criticizes that the fluid approximation of the acceleration radiation which is often used in the estimation of the buoyant force is invalid for the case that the size of the target is much less than a typical wavelength of the acceleration radiation, due to the diffractive effect of wave scattering. In this letter, we argue that even if it is correct that we should calculate the buoyant force as a wave scattering process, its implication in the GSL strongly depends on whether there exists any massless scalar field, that is, S-wave scattering. By reconsidering the diffractive effect by S-wave scattering, we show that if some massless scalar field exists, then the GSL can hold without invoking a new physics, such as an entropy bound for matter.

Takashi Okamura

2000-05-17

412

29 CFR 1926.106 - Working over or near water.  

Code of Federal Regulations, 2010 CFR

...after each use, the buoyant work vests or life preservers shall be inspected for defects which would alter their strength or buoyancy. Defective units shall not be used. (c) Ring buoys with at least 90 feet of line shall be provided and readily...

2010-07-01

413

Dynamical properties of a buoyancy-driven coastal current  

Microsoft Academic Search

The outflow of buoyant waters from major estuaries affects the dynamics of inner continental shelves profoundly as lateral density gradients force an alongshore current. Often the Coriolis force causes the outflow to remain trapped near the coast. We observed one such current, the Delaware Coastal Current, on the inner shelf near the Delaware Estuary on the eastern seaboard of the

Andreas Münchow; Richard W. Garvine

1993-01-01

414

Observation of Centrifugally Driven Interchange Instabilities in a Plasma Confined by a Magnetic Dipole  

E-print Network

], and small ``empty'' flux tubes have been detected [8,9] that may represent the buoyant, inward-moving re mixing is likely to be the mechanism for outward transport of ionized matter emanating from Io, an inner- turn flux. Although the centrifugal interchange instability has been modeled theoretically [10

Mauel, Michael E.

415

Measurement of the global structure of interchange modes driven by energetic electrons trapped in a magnetic dipole  

E-print Network

spacecraft measured a buoyant, inward-moving flux tube within Jupiter's Io plasma torus and also fluctuations physics.1­4 In- terchange motion mixes plasma contained by magnetic flux tubes while minimizing changes,5,6 by creating ``average good curvature'' either on toroidal flux surfaces7 or on the plasma

Mauel, Michael E.

416

Depleted Flux Tubes in the Jovian Magnetosphere  

Microsoft Academic Search

Thin magnetic flux tubes with enhanced field strengths are found in the Io torus. The size of the increase in the magnetic field strength is comparable to that expected if the tubes contained no Io torus plasma. The tubes are found outside the orbit of Io but not inside. Since empty flux tubes should be buoyant in the Io torus

C. T. Russell; M. G. Kivelson; K. K. Khurana

2003-01-01

417

Correcting deep spans in subsea pipelines  

Microsoft Academic Search

A diverless pipeline trenching system unique in nature and working method is described. The system is a highly effective tool for pipeline trenching and particularly for span correction. The system is a 90-ton ROV neutrally buoyant and employing a cutter suction principle to soil excavation. The cutter excavates on one side of the pipe to a controllable depth of cut

Sinclair

1985-01-01

418

“Have a Piss, Drink Ogogoro, Smoke lgbo, but don't take Gbana”Hard and Soft Drugs in Nigeria: A Critical Comparison of Official Policies and the View on the Street  

Microsoft Academic Search

One of the consequences of increased exposure to Western influences has been the spread of drug use among Nigerian young people over the last two decades. There is now a buoyant consumer market for home-grown cannabis, and a smaller market for heroin and cocaine within the country. Under successive military regimes, drug use was either downplayed, or regarded as a

Axel Klein

2001-01-01

419

Instability of a buoyancy-driven coastal jet; The Gaspé Current and its St. Lawrence Precursor  

Microsoft Academic Search

The discharge of the St. Lawrence River drives a buoyant jet which extends along the south shore of the lower St. Lawrence estuary and, combining with the northwest Gulf of St. Lawrence cyclonic gyre, becomes the Gaspé Current. In both the estuarine jet and the Gaspé Current, strong lateral and vertical shears are present. Satellite thermal imagery has shown that

Gordon Mertz; Mohammed I. El-Sabh; Denis Proulx; Alfonso R. Condal

1988-01-01

420

Density variation amongst mid-ocean ridge basalts: Implications for magma mixing and the scarcity of primitive lavas  

Microsoft Academic Search

Densities calculated from glass compositions of observed mid-ocean ridge basalts show that the more primitive melts are likely to be buoyant in more evolved melts. Consideration of this and other physical properties indicates that convective mixing between most basaltic magmas occurs under intermittently turbulent to turbulent conditions (transitional Reynolds Numbers) accounting for the widespread occurrence of hybrid lavas. Hypothetical picritic

R. S. J. Sparks; P. Meyer; H. Sigurdsson

1980-01-01

421

Fluxes and excess temperatures of mantle plumes inferred from their interaction with migrating mid-ocean ridges  

Microsoft Academic Search

The behavior of thermal plumes in the earth's upper mantle is strongly affected by their interaction with nearby mid-ocean ridges. The magnitude of the buoyant topography and the length of the geochemical anomaly induced by plumes at migrating ridge axes provide a way to estimate their excess temperature and discharge rate, and thereby constrain their depth of origin.

Jean-Guy Schilling

1991-01-01

422

Two-phase gravity currents in geological CO2 storage  

Microsoft Academic Search

Geological carbon capture and storage, in which compressed CO2 is injected into deep saline aquifers for permanent storage, forms an integral part of CO2 mitigation strategies. At representative reservoir conditions CO2 is buoyant and may therefore leak into surface waters or the atmosphere. The leakage of CO2 back into the atmosphere may be prevented by the formation of disconnected immobile

J. A. Neufeld; M. Golding; M. A. Hesse; H. E. Huppert

2010-01-01

423

Two-phase gravity currents in CO2 sequestration  

Microsoft Academic Search

Geological carbon capture and storage (CCS), in which compressed CO2 is injected into deep saline aquifers for permanent storage, forms an integral part of CO2 mitigation strategies. At representative reservoir conditions CO2 is buoyant and may therefore leak into surface waters or the atmosphere. The leakage of CO2 back into the atmosphere may be prevented by the formation of disconnected

Jerome Neufeld; Madeleine Golding; Marc Hesse

2010-01-01

424

High-Aspect-Ratio Rotating Cell-Culture Vessel  

NASA Technical Reports Server (NTRS)

Cylindrical rotating cell-culture vessel with thin culture-medium layer of large surface area provides exchange of nutrients and products of metabolism with minimal agitation. Rotation causes averaging of buoyant forces otherwise separating components of different densities. Vessel enables growth of cells in homogeneous distribution with little agitation and little shear stress.

Wolf, David A.; Sams, Clarence; Schwarz, Ray P.

1992-01-01

425

A Tale of Two Spills: Novel Science and Policy Implications of an Emerging New Oil Spill Model  

Microsoft Academic Search

The 2010 Deepwater Horizon oil release posed the challenges of two types of spill: a familiar spill characterized by buoyant oil, fouling and killing organisms at the sea surface and eventually grounding on and damaging sensitive shoreline habitats, and a novel deepwater spill involving many unknowns. The subsurface retention of oil as finely dispersed droplets and emulsions, wellhead injection of

Charles H. Peterson; Sean S. Anderson; Gary N. Cherr; Richard F. Ambrose; Shelly Anghera; Steven Bay; Michael Blum; Robert Condon; Thomas A. Dean; Monty Graham; Michael Guzy; Stephanie Hampton; Samantha Joye; John Lambrinos; Bruce Mate; Douglas Meffert; Sean P. Powers; Ponisseril Somasundaran; Robert B. Spies; Caz M. Taylor; Ronald Tjeerdema; E. Eric Adams

2012-01-01

426

Simulation of oil spills from underwater accidents II: Model verification  

Microsoft Academic Search

A companion paper presented the development of a three-dimensional numerical model to simulate the behaviour of buoyant oil jets that result from underwater accidents. The numerical model was developed based on a Lagrangian integral technique. The model can simulate the behaviour of oil in stratified or unstratified ocean environments. The presence of a multi-directional ambient current is considered. The fluid

Li Zheng; Poojitha D. Yapa

1998-01-01

427

Modelling oil and gas releases from deep water: A review  

Microsoft Academic Search

This paper reviews the fundamental knowledge available to numerically model the behavior of oil, gas, or oil\\/gas mixtures released from underwater. Many studies that were done to understand the buoyant jets and plumes of similar material are also reviewed. A complete reference is provided for models that have been developed to simulate oil and gas released from underwater. Different types

Poojitha D. Yapa; Li Zheng

1997-01-01

428

29 CFR 1926.106 - Working over or near water.  

Code of Federal Regulations, 2013 CFR

...after each use, the buoyant work vests or life preservers shall be inspected for defects which would alter their strength or buoyancy. Defective units shall not be used. (c) Ring buoys with at least 90 feet of line shall be provided and readily...

2013-07-01

429

29 CFR 1926.106 - Working over or near water.  

...after each use, the buoyant work vests or life preservers shall be inspected for defects which would alter their strength or buoyancy. Defective units shall not be used. (c) Ring buoys with at least 90 feet of line shall be provided and readily...

2014-07-01

430

MAGNETIC RECONNECTION, MAGNETIC HELICITY, &  

E-print Network

buoyancy, tension, and reconnection all play a role. They made the analogy that a filament is buoyant, and acts like a balloon. It is line­tied to the photosphere by the tension of magnetic field lines, which act like the tethers that hold a hot­air balloon before launch. When field lines in the filament

Canfield, Richard

431

The Eruptive Flare of 15 November 1991: Preflare Phenomena  

E-print Network

buoyancy, tension, and reconnection all play a role. They drew the analogy that a filament is buoyant, and acts like a balloon. It is line­tied to the photosphere by the tension of mag­ netic field lines, which act like the tethers that hold a hot­air balloon to the ground before launch. When field lines

Canfield, Richard

432

An Aerobot for Global In Situ Exploration of Titan  

Microsoft Academic Search

This paper describes the design and component testing of an aerobot that will be capable of global in situ exploration of Saturn's moon, Titan, over a 6 to 12 month mission lifetime. The proposed aerobot is a propeller-driven, buoyant vehicle that resembles terrestrial airships. However, the extremely cold Titan environment requires the use of cryogenic materials of construction and careful

J. Hall; V. Kerzhanovich; A. Yavrouian; J. Jones; C. White; B. Dudik; A. Elfes

2004-01-01

433

A correlation for the lift-off of many particles in plane Poiseuille flows of Newtonian fluids  

E-print Network

1 A correlation for the lift-off of many particles in plane Poiseuille flows of Newtonian fluids N & Joseph (2001) reported a two-dimensional numerical investigation of the lift-off of 300 circular are suspended or fluidized by lift forces that balance the buoyant weight perpendicular to the flow. Pressure

Joseph, Daniel D.

434

Continental tectonics in the aftermath of plate tectonics  

Microsoft Academic Search

It is shown that the basic tenet of plate tectonics, rigid-body movements of large plates of lithosphere, fails to apply to continental interiors. There, buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is

Peter Molnar

1988-01-01

435

CHARACTERIZATION OF THE DNA OF A NONOCCLUDED BACULOVIRUS, HZ-1V  

EPA Science Inventory

The DNA of the nonoccluded baculovirus (Hz-1V) obtained from the IMC-Hz-1 cell line was characterized by physicochemical and restriction endonuclease techniques. Hz-1V DNA isolated from purified virus had buoyant densities of 1.58 and 1.54 g/ml in CsC1-ethidium bromide density gr...

436

5,-THE MOST RECENT METHODS OF HATCHING FISH EGGS, BY WILLIAM F. PAGE.  

E-print Network

excellent hatching work for nearly all tlie kinds of fish spawning in fresh water, though scarcely any of I is not absolutely necessary to successfully hatch the eggs of fishes spawning in fresh water. The prime requisite is an unfailing water supply of a pressure as nearly constant as is abtainable. For hatching semi-buoyant eggs

437

The End of Flat Earth and the Coupling of the Earth's Geochemical Reservoirs  

Microsoft Academic Search

Because of a warmer and more buoyant geotherm continents were unable to sustain topography larger than 2500 m until the late Archaean. Our numerical experiments suggest that during the Neoarchean (2.8-2.5 Ga) the continental lithosphere evolved through a rheological threshold allowing for the development of significant topography and erosion. This rather rapid strengthening was directly linked to the cooling and

P. F. Rey; N. Coltice

2008-01-01

438

Lattice Boltzmann algorithm for surface tension with greatly reduced microcurrents  

Microsoft Academic Search

We present an algorithm for inserting an interface between the immiscible phases of a multicomponent lattice Boltzmann fluid which is based solely upon the appropriate continuum physics: stress boundary conditions and continuity of velocity. Results are presented for the algorithm when applied to static, neutrally buoyant drops. It is shown that the present algorithm gives a significant reduction in the

S. V. Lishchuk; C. M. Care; I. Halliday

2003-01-01

439

Constraining mantle density structure using geological evidence of surface uplift rates: The case of the African Superplume  

Microsoft Academic Search

We explore the hypothesis that southern Africa is actively being uplifted by a large-scale, positively buoyant structure within the mid-lower mantle. Using a new formulation in which dynamic topography and uplift rate are jointly used, we place constraints on mantle density and viscosity. The solution of the momentum equation is coupled with the advection of the density field to solve

Michael Gurnis; Jerry X. Mitrovica; Jeroen Ritsema; Hendrik-Jan van Heijst

2000-01-01

440

Determination of Bacterial Antibiotic Resistance Based on Osmotic Shock Response  

E-print Network

Determination of Bacterial Antibiotic Resistance Based on Osmotic Shock Response Scott M. Knudsen. This behavior can be used to differentiate between an antibiotic-resistant and an antibiotic-susceptible strain- sion of the SMR for rapid detection of antibiotic resistance. The buoyant densities of bacterial cells

Manalis, Scott

441

46 CFR 160.002-4 - Construction.  

Code of Federal Regulations, 2010 CFR

...for child size, which shall be heat-sealed tight. The heat-sealed pad seams shall show...volume of the finished individual heat-sealed buoyant pad inserts shall...the arrangement of a snap hook and pre-threaded double Dee rings...

2010-10-01

442

46 CFR 160.002-4 - Construction.  

Code of Federal Regulations, 2011 CFR

...for child size, which shall be heat-sealed tight. The heat-sealed pad seams shall show...volume of the finished individual heat-sealed buoyant pad inserts shall...the arrangement of a snap hook and pre-threaded double Dee rings...

2011-10-01

443

Particle laden flows through an inverted chimney with applications to ocean carbon sequestration  

E-print Network

Plumes of negatively buoyant hydrate particles, formed by reacting liquid CO[subscript 2] with seawater at ocean depths of 1000–1500 m, have been suggested as a way to help sequester CO[subscript 2]. The vertical flux of ...

Chow, Aaron C.

444

Respiratory and plumage gas volumes in unrestrained diving ducks ( Aythya affinis)  

Microsoft Academic Search

Closed-circuit plethysmography and inert gas equilibration analysis were used to measure the volumes of gas in the respiratory system and plumage at the end of voluntary dives in unrestrained lesser scaup (Aythya affinis). Total (respiratory plus plumage) gas volumes were measured by helium dilution and estimated from body mass, body tissue density and buoyant force. These two techniques yielded results

Richard Stephenson

1995-01-01

445

Large Woody Debris Structures for Sand-Bed Channels  

Microsoft Academic Search

Described is a method for channel erosion control and habitat rehabilitation featuring intermittent placement of structures made of large woody debris. This method is expressly tailored to address severe problems typical of incised channels with little sediment coarser than sand. In these types of environments, buoyancy forces are typically more important factors in woody debris stability than fluid drag. Buoyant

F. Douglas Shields

2004-01-01

446

INTRODUCTION The properties of non-Brownian particles in a liquid are usual-  

E-print Network

a unique opportunity to inves- tigate the many body hydrodynamic interactions that determine their basic METHODS To create neutrally buoyant suspensions, uniform borosilicate glass beads (diameter a = 63 ± 11 µm (a low viscosity aqueous solution of lithium heteropolytungstates) and water. The beads were sieved

Page, John

447

Annual growth rate of the calcareous red alga Lithothamnion corallioides (Corallinales, Rhodophyta) in the Bay of Brest, France  

Microsoft Academic Search

Lithothamnion corallioides Crouan et Crouan (Rhodophyta, Corallinales) is the main constituent of the maerl beds of the Bay of Brest (Atlantic coast of western Brittany). Its growth rate was measured monthly in situ during one year. Growth rates were obtained by an adaptation of the buoyant weight technique. The highest daily growth rate was observed in July and reached 0.26

P. Potin; J. Y. Floc'h; C. Augris; J. Cabioch

1990-01-01

448

Basalt Reactivity Variability with Reservoir Depth in Supercritical CO2 and Aqueous Phases  

Microsoft Academic Search

Long term storage of CO in geologic formations is currently considered the most attractive option to reduce greenhouse gas emissions while continuing to utilize fossil fuels for energy production. Injected CO is expected to reside as a buoyant water-saturated supercritical fluid in contact with reservoir rock, the caprock system, and related formation waters. As was reported for the first time

Herbert T. Schaef; B. Peter McGrail; Antionette T. Owen

2011-01-01

449

The initial giant umbrella cloud of the May 18th, 1980, explosive eruption of Mount St. Helens  

USGS Publications Warehouse

The initial eruption column of May 18th, 1980 reached nearly 30 km altitude and released 1017 joules of thermal energy into the atmosphere in only a few minutes. Ascent of the cloud resulted in forced intrusion of a giant umbrella-shaped cloud between altitudes of 10 and 20 km at radial horizontal velocities initially in excess of 50 m/s. The mushroom cloud expanded 15 km upwind, forming a stagnation point where the radial expansion velocity and wind velocity were equal. The cloud was initiated when the pyroclastic blast flow became buoyant. The flow reduced its density as it moved away from the volcano by decompression, by sedimentation, and by mixing with and heating the surrounding air. Observations indicate that much of the flow, covering an area of 600 km2, became buoyant within 1.5 minutes and abruptly ascended to form the giant cloud. Calculations are presented for the amount of air that must have been entrained into the flow to make it buoyant. Assuming an initial temperature of 450??C and a magmatic origin for the explosion, these calculations indicate that the flow became buoyant when its temperature was approximately 150??C and the flow consisted of a mixture of 3.25 ?? 1011 kg of pyroclasts and 5.0 ?? 1011 kg of air. If sedimentation is considered, these figures reduce to 1.1 ?? 1011 kg of pyroclasts and 1.0 ?? 1011 kg of air. ?? 1986.

Sparks, R.S.J.; Moore, J.G.; Rice, C.J.

1986-01-01

450

Fluid dynamics in explosive volcanic vents and craters  

Microsoft Academic Search

Explosive volcanic jets can transition to buoyant plumes or collapse to form pyroclastic density currents depending on their ability to entrain and heat the ambient air. Recent one-dimensional (1D) analysis shows that fluid acceleration through volcanic vents and craters changes the velocity and pressures within these jets sufficiently enough to be a first order control on plume dimensions and therefore

Darcy Ogden

451

Dynamics of Laboratory Diapir and Plume Models  

Microsoft Academic Search

The low Reynolds number dynamics of a thin layer of fluid bounded below by a flat horizontal boundary and moving buoyantly through a fluid of another viscosity and density is observed by means of model experiments and is described theoretically. Three distinct stages of growth were observed. The first stage is described by a linearized Rayleigh-Taylor instability, for which previous

John A. Whitehead; Douglas S. Luther

1975-01-01

452

NEW DEVELOPMENT IN DISPERSION EXPERIMENTS AND MODELS FOR THE CONVECTIVE BOUNDARY LAYER  

EPA Science Inventory

We present recent experiments and modeling studies of dispersion in the convective boundary layer (CBL) with focus on highly-buoyant plumes that "loft" near the CBL top and resist downward mixing. Such plumes have been a significant problem in earlier dispersion models; they a...

453

Remote acoustic imaging of the plume from a submarine spring in an arctic fjord.  

PubMed

Acoustic backscatter observations at 200 kilohertz were made of the buoyant plume from a submarine spring at a depth of 47 meters in Cambridge Fiord, Baffin Island. Vertical velocities of up to 37 centimeters per second are inferred from the ascent rates of discrete scattering structures in the plume. PMID:17782423

Hay, A E

1984-09-14

454

J. Fluid Mech. (2011), vol. 686, pp. 525. c Cambridge University Press 2011 5 doi:10.1017/jfm.2011.272  

E-print Network

of flowing behaviours (e.g. shear thinning, shear thickening and thixotropy) depending on the microstructureJ. Fluid Mech. (2011), vol. 686, pp. 5­25. c Cambridge University Press 2011 5 doi:10.1017/jfm.2011 are measured in dense suspensions of neutrally buoyant non-Brownian spheres dispersed in a Newtonian fluid

Pouliquen, Olivier

455

Influence of geometric parameters on the eventual buoyancy stratification that develops due to architectural exchange flow  

E-print Network

the dense fluid, a buoyant plume ascends resulting, over time, in a vertical density stratification through that initially contains the dense fluid is comparatively small in volume. The associated complications are (i- mercial buildings [2]. This necessitates a fundamental reconsider- ation in the way we operate buildings

Flynn, Morris R.

456

Hydrothermal plume dynamics on Europa: Implications for chaos formation  

E-print Network

a liquid ocean to the base of its ice shell. This process has been implicated in the formation of chaos existing work describing buoyant plumes in a rotating, unstratified environment. We discuss the scaling scaling constants and to visualize plume behavior in a Europa-like parameter regime. We predict

Pierrehumbert, Raymond

457

Apparatus for Teaching Physics.  

ERIC Educational Resources Information Center

Describes the following: a device which converts the displacement of a pendulum into an electric signal and is used as a voltage generator of low frequencies; a turn-by-turn transformer demonstration; how to remove the buoyant force on a piece of cork immersed in water; and how to demonstrate Coulomb's Law on the overhead projector. (GA)

Gottlieb, Herbert H., Ed.

1979-01-01

458

Chapter 6: Forces in Fluids Did you read chapter 6  

E-print Network

, and pressure acts perpendicular to the surface of submerged objects #12;1/20/2010 4 Archimedes Principle. normal force · b. friction A volume of water in pool Weight Buoyant Force Archimedes Principle An object Demo Floating Objects According to Archimedes Principle, an object will sink until its weight equals

Hart, Gus

459

Problem-Based Test: Replication of Mitochondrial DNA during the Cell Cycle  

ERIC Educational Resources Information Center

Terms to be familiar with before you start to solve the test: cell cycle, generation time, S-phase, cell culture synchronization, isotopic pulse-chase labeling, density labeling, equilibrium density-gradient centrifugation, buoyant density, rate-zonal centrifugation, nucleoside, nucleotide, kinase enzymes, polymerization of nucleic acids,…

Setalo, Gyorgy, Jr.

2013-01-01

460

Location and extent of Tertiary structures in Cook Inlet Basin, Alaska, and mantle dynamics that focus deformation and subsidence  

USGS Publications Warehouse

Subduction of the buoyant Yakutat microplate likely caused deformation to be focused preferentially in upper Cook Inlet. The upper Cook Inlet region has both the highest degree of shortening and the deepest part of the Neogene basin. This forearc region has a long-wavelength magnetic high, a large isostatic gravity low, high conductivity in the lower mantle, low p-wave velocity (Vp), and a high p-wave to shear-wave velocity ratio (Vp/Vs). These data suggest that fluids in the mantle wedge caused serpentinization of mafic rocks, which may, at least in part, contribute to the long-wavelength magnetic anomaly. This area lies adjacent to the subducting and buoyant Yakutat microplate slab. We suggest the buoyant Yakutat slab acts much like a squeegee to focus mantle-wedge fluid flow at the margins of the buoyant slab. Such lateral flow is consistent with observed shear-wave splitting directions. The additional fluid in the adjacent mantle wedge reduces the wedge viscosity and allows greater corner flow. This results in focused subsidence, deformation, and gravity anomalies in the forearc region.

Haeussler, Peter J.; Saltus, Richard W.

2011-01-01

461

Oceanic transport of calcified eggs: taphonomic and biogeographic implications  

Microsoft Academic Search

Estimates of the temporal and spatial resolution of fossil egg assemblages are required to constrain the inferences that can logically be drawn during assemblage analysis. Consequently, understanding egg transport mechanisms is required before conclusions are developed. Bird eggs are buoyant during part of development and can float from near shore nests during high tides, storm surges, or flooding. Complete and

Thomas Evans

2012-01-01

462

Mechanism for generating power from wave motion on a body of water  

SciTech Connect

A mechanism for generating power from wave motion on a body of water is described. The mechanism includes a buoyant body which is adapted to float on a body of water and to roll and pitch in response to the wave motion of the water. A gyro-wave energy transducer is mounted on the buoyant body for translating the pendulum-like motions of the buoyant body into rotational motion. The gyro-wave energy transducer includes a gimbal comprised of first and second frames, with the first frame being pivotally mounted to the second frame and the second frame being pivotally mounted to the buoyant body. A gyroscope is mounted to the first frame for rotation about an axis perpendicular to the axes of rotation of the first and second frames. A motor/generator is coupled to the gyroscope for maintaining a controlled rotational velocity for the gyroscope. Transferring members are associated with one of the first and second frames for transferring torque of one of the first and second frames to the gyroscope about an axis that is perpendicular to that of the gyroscope which results in rotation of the other of the first and second frames. An electrical generator is responsive to the relative rotational movement of the first and second frames for generating electrical energy. A storage battery is mounted on the buoyant body for storing and releasing electrical energy and is operatively coupled to the motor/generator and the electrical generator. A control circuit is associated with the generator and the motor/generator unit of the gyroscope and is responsive to the time rate of change of current produced by the generator for controlling the rotational velocity of the gyroscope in order to maintain maximum power output from the electrical generator.

Sachs, G.A.; Sachs, H.K.

1982-09-28

463

Opening and closing slab windows in congested subduction zones  

NASA Astrophysics Data System (ADS)

Subduction zones often try to swallow buoyant material which is embedded in the oceanic lithosphere: plume material or hotspot residues, oceanic plateaux, and fragments of continental material. This often results in the formation of a slab window and it has been shown (Mason et al, 2010; Betts et al, 2012) that this window strongly influences the subsequent evolution of the slab and the advance/retreat rate of the trench. The buoyant material typically pushes the trench into a local state of advance, and the creation of the slab window allows the rest of the trench to retreat as the mantle behind the slab flows in through the window. This situation is inherently unstable: if the buoyancy anomaly is finite in size, then the retreating trench will soon move behind the anomaly and juxtapose negatively buoyant oceanic lithosphere with active subduction. This creates the potential to close the slab window and, in doing so, transfer the buoyant material to the over-riding plate. Models show that this closure of the window initially occurs through a lateral rollback process followed by a catastrophic re-initiation of subduction behind the colliding buoyant anomaly. This rollback leaves a characteristic, tightly rolled remnant in the mantle and significant rotation in the over-riding plate and the newly-docked block. The over-riding plate is thrown into extension perpendicular to the original orientation of the trench. This same situation applies at the late-stages of a closing ocean due to the passive margin geometry and the presence of debris collected from the closing ocean floor and it seems likely that these models can also be applied to the complicated geometry of subduction in such environments. Mason, W. G.; Moresi, L.; Betts, P. G. & Miller, M. S. Three-dimensional numerical models of the influence of a buoyant oceanic plateau on subduction zones Tectonophysics, 2010, 483, 71-79 P. Betts, W. Mason, L. Moresi, The influence of mantle plumes on subduction zone dynamics, Geology, 40, 739-742 (2012)

Moresi, Louis

2013-04-01

464

Lithospheric processes  

SciTech Connect

The authors used geophysical, geochemical, and numerical modeling to study selected problems related to Earth's lithosphere. We interpreted seismic waves to better characterize the thickness and properties of the crust and lithosphere. In the southwestern US and Tien Shari, crust of high elevation is dynamically supported above buoyant mantle. In California, mineral fabric in the mantle correlate with regional strain history. Although plumes of buoyant mantle may explain surface deformation and magmatism, our geochemical work does not support this mechanism for Iberia. Generation and ascent of magmas remains puzzling. Our work in Hawaii constrains the residence of magma beneath Hualalai to be a few hundred to about 1000 years. In the crust, heat drives fluid and mass transport. Numerical modeling yielded robust and accurate predictions of these processes. This work is important fundamental science, and applies to mitigation of volcanic and earthquake hazards, Test Ban Treaties, nuclear waste storage, environmental remediation, and hydrothermal energy.

Baldridge, W. [and others

2000-12-01

465

Dissipative inertial transport patterns near coherent Lagrangian eddies in the ocean  

E-print Network

Recent developments in dynamical systems theory have revealed long-lived and coherent Lagrangian (i.e., material) eddies in incompressible, satellite-derived surface ocean velocity fields. Paradoxically, observed drifting buoys and floating matter tend to create dissipative-looking patterns near oceanic eddies, which appear to be inconsistent with the conservative fluid particle patterns created by coherent Lagrangian eddies. Here we show that inclusion of inertial effects (i.e., those produced by the buoyancy and size finiteness of an object) in a rotating two-dimensional incompressible flow context resolves this paradox. Specifically, we obtain that anticyclonic coherent Lagrangian eddies attract (repel) negatively (positively) buoyant finite-size particles, while cyclonic coherent Lagrangian eddies attract (repel) positively (negatively) buoyant finite-size particles. We show how these results explain dissipative-looking satellite-tracked surface drifter and subsurface float trajectories, as well as satellite-derived \\emph{Sargassum} distributions.

F. J. Beron-Vera; M. J. Olascoaga; G. Haller; M. Farazmand; J. Trinanes; Y. Wang

2014-08-27

466

Dissipative inertial transport patterns near coherent Lagrangian eddies in the ocean  

E-print Network

Recent developments in dynamical systems theory have revealed long-lived and coherent Lagrangian (i.e., material) eddies in incompressible, satellite-derived surface ocean velocity fields. Paradoxically, observed drifting buoys and floating matter tend to create dissipative-looking patterns near oceanic eddies, which appear to be inconsistent with the conservative fluid particle patterns created by coherent Lagrangian eddies. Here we show that inclusion of inertial effects (i.e., those produced by the buoyancy and size finiteness of an object) in a rotating two-dimensional incompressible flow context resolves this paradox. Specifically, we obtain that anticyclonic coherent Lagrangian eddies attract (repel) negatively (positively) buoyant finite-size particles, while cyclonic coherent Lagrangian eddies attract (repel) positively (negatively) buoyant finite-size particles. We show how these results explain dissipative-looking satellite-tracked surface drifter and subsurface float trajectories, as well as satell...

Beron-Vera, F J; Haller, G; Farazmand, M; Trinanes, J; Wang, Y

2014-01-01

467

Derivation of the Buoyancy Ratio Equation from the Bubble Migration Model  

SciTech Connect

Most Hanford waste tanks do not have buoyant displacements, even those with deep submerged sediment layers and moderate gas generation rates. Most tanks apparently achieve a steady state where gas generation is balanced by a steady background release so they never attain the neutral buoyancy gas fraction. In a few tanks, however, gas generation exceeds the background release, which allows gas to accumulate to the point of buoyancy. The mechanism for this background release is unknown, but we postulate that the background release is a slow migration of bubbles through the sediment. This document, an addendum to PNNL-13337, ''Preventing Buoyant Displacement Gas Release Events in Hanford Double-Shell Waste Tanks,'' presents the derivation of the equation in the Bubble Migration Model that explains buoyancy.

Stewart, Charles W.; Meyer, Perry A.

2005-04-26

468

Investigation of the free flow electrophoretic process. Volume 2: Technical analysis  

NASA Technical Reports Server (NTRS)

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. The results of tests performed using various methods of electrophoresis using supportive media show that the mobility and the ability to separate were essentially independent of concentration, providing promise of being able to perform electrophoresis with higher inlet concentrations in space.

Weiss, R. A.; Lanham, J. W.; Richman, D. W.; Walker, C. D.

1979-01-01

469

Feedbacks of phytoplankton surface mats on ocean physics  

NASA Astrophysics Data System (ADS)

The effects of phytoplankton on ocean physics through the feedback by light absorption have been investigated repeatedly. In contrast, additional feedback mechanisms involving positively buoyant phytoplankton have been largely ignored. However, extensive surface mats of buoyant cyanobacteria, as they occur regularly in the Baltic Sea in summer, may have significant effects on wind drag and albedo. Using an ecosystem model that is embedded in a water column or an ocean circulation model, we study the relative importance of all three feedback mechanisms. We show that surface floating cyanobacteria substantially alter their environment. The light absorption and wind drag feedbacks, however, are stronger than the albedo feedback. Overall, we find that the increase of sea surface temperatures and cooling subsurface mediated by cyanobacteria also modify ocean circulation patterns. Since the abundance of surface floating cyanobacteria is expected to increase in future, we recommend to include these biological-physical feedback mechanisms in the next generation of ocean climate models.

Hense, Inga; Sonntag, Sebastian

2014-05-01

470

Rivers as a source of marine litter--a study from the SE Pacific.  

PubMed

Composition and abundance of persistent buoyant litter (plastics, polystyrene and manufactured wood) were investigated at riversides and on adjacent coastal beaches of four rivers flowing into the SE Pacific Ocean. Persistent buoyant litter made up the main share of litter at riversides (36-82%) and on coastal beaches near the river mouths (67-86%). The characteristic litter composition of each river is attributable to human influences along its course. Riverine litter items were deposited to both sides of the river mouths on coastal beaches, and their abundance generally declined with distance from the river mouth. However, maximum litter accumulations were often found on beaches north of the river mouth, suggesting a long-term influence of the prevailing equatorward low-level jet along the Chilean coast. The results confirm that riverine transport has an important impact on litter abundances on coastal beaches. PMID:24726186

Rech, S; Macaya-Caquilpán, V; Pantoja, J F; Rivadeneira, M M; Jofre Madariaga, D; Thiel, M

2014-05-15

471

Study of buoyancy systems for flight vehicles  

NASA Technical Reports Server (NTRS)

The performance potential of buoyant systems and flexible structures used in air vehicles for short-haul passenger transportation is discussed. The study was intended only to determine if sufficient performance potential existed, and to provide a focus for a more extensive design study, if such a study appeared desirable. A relatively conventional helium system was examined along with a more unusual configuration employing hot-air as the buoyant fluid. Both configurations were examined in the VTOL and STOL modes of operation. The helium system appears to have some superiority in the VTOL mode, while the hot-air system has a superiority in the STOL mode. Both configurations exhibit sufficient performance potential to suggest that a much more extensive design study might well be undertaken.

Havill, C. D.; Williams, L. J.

1972-01-01

472

Large Prandtl number finite-amplitude thermal convection with Maxwell viscoelasticity. [earth mantle rheological model  

NASA Technical Reports Server (NTRS)

It has long been known that the earth behaves viscoelastically. Viscoelasticity may be of importance in two aspects of mantle convection, including time-dependent behavior and local storage of recoverable work. The present investigation makes use of thermal convection in a box as a prototype of mantle flow. It is demonstrated that recoverable work can be important to the local mechanical energy balance in the descending lithosphere. It is shown that, even when assuming large viscoelastic parameters, an inherent time-dependence of viscoelastic convection appears only in local exchanges of mechanical energy. There is no strong exchange between buoyant potential energy and recoverable strain energy in the Rayleigh number range investigated. The investigation is mainly concerned with viscoelastic effects occurring on a buoyant time scale. It is found that viscoelastic effects have a negligible influence on the long term thermal energetics of mantle convection.

Ivins, E. R.; Unti, T. W. J.; Phillips, R. J.

1982-01-01

473

Aeromechanical stability analysis of a multirotor vehicle with application to hybrid heavy lift helicopter dynamics  

NASA Technical Reports Server (NTRS)

The Hybrid Heavy Lift Helicopter (HHLH) is a potential candidate vehicle aimed at providing heavy lift capability at low cost. This vehicle consists of a buoyant envelope attached to a supporting structure. Four rotor systems are also attached to the supporting structure. Nonlinear equations of motion capable of modeling the dynamics of this multi-rotor/support frame/vehicle system have been developed and used to study the fundamental aeromechanical stability characteristics of this class of vehicles. The mechanism of coupling between the blades, supporting structure and rigid body modes is identified and the effect of buoyancy ratio (buoyant lift/total weight) on the vehicle dynamics is studied. It is shown that dynamics effects have a major role in the design of such vehicles. The analytical model developed is also useful for studying the aeromechanical stability of single rotor and tandem rotor coupled rotor/fuselage systems.

Venkatesan, C.; Friedmann, P. P.

1984-01-01

474

Subduction of the oceanic Hikurangi Plateau and its impact on the Kermadec arc  

NASA Astrophysics Data System (ADS)

Large igneous province subduction is a rare process on Earth. A modern example is the subduction of the oceanic Hikurangi Plateau beneath the southern Kermadec arc, offshore New Zealand. This segment of the arc has the largest total lava volume erupted and the highest volcano density of the entire Kermadec arc. Here we show that Kermadec arc lavas south of ~32°S have elevated Pb and Sr and low Nd isotope ratios, which argues, together with increasing seafloor depth, forearc retreat and crustal thinning, for initial Hikurangi Plateau—Kermadec arc collision ~250?km north of its present position. The combined data set indicates that a much larger portion of the Hikurangi Plateau (the missing Ontong Java Nui piece) than previously believed has already been subducted. Oblique plate convergence caused southward migration of the thickened and buoyant oceanic plateau crust, creating a buoyant ‘Hikurangi’ mélange beneath the Moho that interacts with ascending arc melts.

Timm, Christian; Davy, Bryan; Haase, Karsten; Hoernle, Kaj A.; Graham, Ian J.; de Ronde, Cornel E. J.; Woodhead, Jon; Bassett, Dan; Hauff, Folkmar; Mortimer, Nick; Seebeck, Hannu C.; Wysoczanski, Richard J.; Caratori-Tontini, Fabio; Gamble, John A.

2014-09-01

475

A Review of Balloon Concepts for Titan  

NASA Astrophysics Data System (ADS)

Concepts for lighter-than-air exploration of Titan are reviewed. Logical vehicle designs with existing power sources (primary batteries, or 100 We-class radioisotope power supplies) are strongly bifurcated into small (few kg) vehicles with lifetimes of only a few hours/days, or larger (100 kg+) vehicles with lifetime of months to years. A wide range of the latter class of vehicle exists, including buoyant-gas and hot-air (Montgolfière) concepts, with and without altitude control or propulsion. An attractive intermediate (10s of kg, but long-lived) class of buoyant gas balloon would be enabled by small (0.5-10 We) radioisotope power supplies, not presently available in the USA. The marginal feasibility of high altitude solar-powered balloons is discussed.

Lorenz, R. D.

476

Apparatus for converting the surface motion of a liquid body into usable power  

SciTech Connect

Apparatus is described for converting wave motion at the surface of a supporting medium into usable power and including a buoyant main body forming a housing for a plurality of pumps and a float system connected thereto such that wave induced relative motion between the body and the component parts of the float system causes actuation of the pumps. The pumps intake water from the supporting medium and pumps it through an effluent conduit to a remote location where it is used to perform useful work. The apparatus can be scuttled during storms, with effective resurrection made possible by using the buoys of the float system to store air, or other fluid, under pressure until needed to purge the buoyant main body of water.

Smith, W.W.

1984-11-06

477

User`s guide for the CALPUFF dispersion model. Final report  

SciTech Connect

This report describes the CALPUFF dispersion model and associated processing programs. The CALPUFF model described in this report reflect improvements to the model including (1) new modules to treat buoyant rise and dispersion from area sources (such as forest fires), buoyant line sources, and volume sources, (2) an improved treatment of complex terrain, (3) additional model switches to facilitate its use in regulatory applications, (4) an enhanced treatment of wind shear through puff splitting, and (4) an optional PC-based GUI. CALPUFF has been coupled to the Emissions Production Model (EPM) developed by the Forest Service through an interface processor. EPM provides time-dependent emissions and heat release data for use in modeling controlled burns and wildfires.

NONE

1995-07-01

478

Biomimetic mechanics behaviors of the strider leg vertically pressing water  

NASA Astrophysics Data System (ADS)

Water striders capture the amazing feature to walk on water surface, and this phenomenon triggered extensive investigations in the past decades. We model the strider leg as a fiber vertically pressing into water surface and explore some striking mechanics behaviors in this process. First, the meniscus morphology is exactly solved by a numerical scheme. Based upon this solution, a non-dimensional parameter is defined in order to properly characterize the "capillary effect" of the objects with different volumes. The discussion of the buoyant force shows that the apparent contact angle has little impact on the variation of the water-supporting force. Besides this, there is no need for the strider leg to pierce into water, for the pinning of the triple contact line ensures a bigger buoyant force. In addition, the radius of the leg should be in an appropriate range to support the body weight. These analyses may cast light on how to design new-typed miniature aquatic devices.

Liu, Jianlin; Sun, Jing; Mei, Yue

2014-06-01

479

K9 water searches: scent and scent transport considerations.  

PubMed

Increased use of water search dogs for detecting submerged bodies has created the need for a better understanding of scent emanating from the bodies and how it transits the water to the dog's nose. A review of recent literature identifies likely scent sources, potential scent transport processes, and research needs. Scent sources include gases in bubbles or dissolved in the water, liquids as buoyant plumes and droplets or dissolved in the water, and solids consisting of buoyant particulates with secretions, bacteria, and body fluids. Potential transport processes through the water include buoyancy, entrainment, and turbulence. Transport processes from the water surface into the air include volatilization and evaporation enhanced by bubble bursting, breaking waves, splashing, and wind spray. Implications for the use of water search dogs are examined. Observations of submerged, decomposing bodies are needed to quantify the physical and chemical characteristics of the scent and scent transport processes. PMID:21480897

Osterkamp, Tom

2011-07-01

480

Cosmic Ray Feedback  

NASA Astrophysics Data System (ADS)

Cosmic rays produced or deposited at sites in hot cluster gas are thought to provide the pressure that forms X-ray cavities. While cavities have a net cooling effect on cluster gas, young, expanding cavities drive shocks that increase the local entropy. Cavities also produce radial filaments of thermal gas and are sources of cluster cosmic rays that diffuse through cavity walls, as in Virgo where a radio lobe surrounds a radial thermal filament. Cosmic rays also make the hot gas locally buoyant, allowing large masses of low entropy gas to be transported out beyond the cooling radius. Successive cavities maintain a buoyant outflow that preserves the cluster gas temperature and gas fraction profiles and dramatically reduces the cooling rate onto the central black hole.

Mathews, William G.

2009-12-01

481

Correcting deep spans in subsea pipelines  

SciTech Connect

A diverless pipeline trenching system unique in nature and working method is described. The system is a highly effective tool for pipeline trenching and particularly for span correction. The system is a 90-ton ROV neutrally buoyant and employing a cutter suction principle to soil excavation. The cutter excavates on one side of the pipe to a controllable depth of cut with respect to the pipe. A combination of single and multipass cutting is possible. The trenching machine operates through an umbilical cable with the mother vessel. The neutrally buoyant machine is flown down to the seafloor by means of eight propellers. A sensor package is used to locate the pipeline and the machine clamps onto the pipe using it as a track during trenching. The specially developed handling system, based on a 130-ton U-frame with umbilical heave compensating unit, allows for operation and deployment in up to three meter significant wave height.

Sinclair, M.

1985-11-01

482

Floating microspheres: to prolong the gastric retention time in stomach.  

PubMed

A gastroretentive drug delivery system with prolong retention time in the stomach have great practical importance for drugs with an absorption window in the upper small intestine. Floating drug delivery system are expected to remain buoyant in the gastric content for prolong duration of time thus enhance the bioavailability of drugs. There are several gastroretentive drug delivery systems, which are floating microspheres, granules, tablets, powder, pills, laminated films and capsules. Floating microspheres are gaining special attention because of their wide applicability in the targeting of drug to stomach. Floating microspheres have several advantages, that they remain buoyant in the stomach and distributed uniformly to avoid the vagaries of gastric emptying and release the drug for prolong period of time. PMID:22023206

Bhadouriya, Priyanka; Kumar, Manish; Pathak, Kamla

2012-05-01

483

Rheoceptive mediators of graviperception in a water flea: Morphological implications of antennal-socket setae in daphnia magna  

NASA Technical Reports Server (NTRS)

Aquatic microcrustaceans of the genus Daphnia are known to orient to light during the day. At night, in the absence of visual cues, daphnids were suspected of maintaining equilibrium by monitoring the direction of gravity through their swimming antennae. Recent investigations using simulated, weightlessness conditions coupled with absence of illumination revealed hair like structures or setae on the basal, articulating socket of the antennae that, when surgically removed, resulted in disorientation. Given the simulated weightlessness or neutrally buoyant condition that eliminated sinking of the normally negatively buoyant Daphnia, it was proposed that the antennal socket setae function as rheoceptors stimulated by the upward rush of water currents during gravity induced, sinking phase of daphnid swimming movements. This rheoceptively mediated, gravity perception hypothesis is further supported by morphological investigations. Scanning electron micrographs indicate that antennal socket setae are anatomically similar to proprioceptors used by higher crustaceans to monitor gravitational direction.

Meyers, D. G.

1984-01-01

484

Sedimentation equilibrium and the generalized Archimedes' principle.  

PubMed

The buoyancy concept is critically re-examined for applications to dispersions of nano-particles, such as colloids, proteins, or macromolecules. It is shown that when the size of the buoyant particle is not too different (say, at most a factor of ten) from the size of the dispersed particles, new intriguing phenomena emerge, leading to the violation of the Archimedes' principle. The resulting buoyancy force depends not only on the volume of the particle and on the mass density of the dispersion, but also on the relative size of the particles, on their geometry, and on the interactions between the buoyant particle and the fluid. Explicit expressions for such a generalized Archimedes' principle are obtained and the results are tested against targeted experiments in colloidal dispersions. PMID:23534662

Parola, Alberto; Buzzaccaro, Stefano; Secchi, Eleonora; Piazza, Roberto

2013-03-21

485

Small Scale Field Study of an Ocean CO 2 Plume  

Microsoft Academic Search

We have carried out a small-scale (?20 l) CO2 sequestration experiment off northern California (684 m depth, ?5°C, background ocean pH ?7.7) designed as an initial investigation\\u000a of the effects of physical forcing of the fluid, and the problem of sensing the formation of a low pH plume. The buoyant CO2 was contained in a square frame 1.2 m high,

Peter G. Brewer; Edward Peltzer; Izuo Aya; Peter Haugan; Richard Bellerby; Kenji Yamane; Ryuji Kojima; Peter Walz; Yasuharu Nakajima

2004-01-01

486

The case of artisanal mining in Bolivia: Local participatory development and mining investment opportunities  

Microsoft Academic Search

Despite the buoyant expansion of Latin America's mining sector, the small-scale mining sub-sector remains marginalized. For many countries with small-scale mining resources, the way forward to sustainable mining development is not clear. Activities, in far too many cases, have led to environmental damage, social inequity and political violence among mining communities. This article, through a case study of the Bolivian

Eduardo R. Quiroga

2002-01-01

487

Evidence for the de novo synthesis of glutamate dehydrogenase during the spherulation of Physarum polycephalum  

Microsoft Academic Search

Under conditions of CsCl-equilibrium sedimentation, glutamate dehydrogenase in extracts made from spherulating Physarum microplasmodia forms a symmetrical band with a buoyant density of ?25=1.2788. When a mixture of deuterated amino acids is present in the salts medium during spherulation, the density shifts to ?25=1.2962, indicating de novo synthesis of this enzyme. Experiments with actinomycin-C and cycloheximide suggest that this de

A. Hüttermann; S. M. Elsevier; W. Eschrich

1971-01-01

488

Orbital Processing of High-Quality Zn-Alloyed CdTe Compound Semiconductors  

NASA Technical Reports Server (NTRS)

The objective of this research is to investigate the influences of gravitationally-dependent phenomena (hydrostatic and buoyant) on the growth and quality of doped and alloyed Cadmium-Zinc-Telluride (CdZnTe) crystals grown by the modified seeded Bridgman-Stockbarger technique. It is hypothesized that the damping of the gravitationally-dependent buoyancy convection will substantially enhance chemical homogeneity and the near-elimination of hydrostatic pressure will enable significant reduction in defect (dislocations and twins) density.

Larson, David J., Jr.; Dudley, M.; Raghothamachar, B.; Alexander, J. I. D.; Carlson, F. M.; Gillies, D.; Volz, M.; Ritter, T. M.; DiMarzio, D.

1999-01-01

489

Turning of a Short-Length Cable Using Flapping Fin Propulsion  

Microsoft Academic Search

In this paper, the context of several self-propelled, short-length cables, embedded with passive sensors for environ- mental diagnostics and swimming efficiently in formation over long duration and in shallow water, is considered. The basic problem of this volumetric diagnostic—namely, the low-speed motion control of a short-length, neutrally buoyant cable—is examined. More specifically, the constant-rate, circular turning of a 7-m-long cable

Promode R. Bandyopadhyay; Henry A. Leinhos; J. Dana Hrubes; Norman Toplosky; Joshua Hansen

2011-01-01

490

Dynamic Large-Eddy Simulation of Droplet Effects on a Reacting Plume in Countercurrent Configuration  

Microsoft Academic Search

The effects of evaporating droplets on a reacting plume have been investigated using large-eddy simulation (LES) with dynamic subgrid flow models. A countercurrent configuration, in which droplets are discharged downward toward a rising buoyant reacting plume, is used to mimic an idealized small-scale, water-based fire suppression system. Parametric studies have been conducted by varying the initial Stokes number (St0) or

J. Xia; K. H. Luo; H. Zhao

2011-01-01

491

Large eddy simulation of fire plumes  

Microsoft Academic Search

FireFOAM, a new fire modeling code based on the OpenFOAM platform (www.openfoam.org), is developed and applied to model a series of purely buoyant fire plumes with heat release rates from 14 to 58kW. The calculations are compared with McCaffrey’s (1979) experiments. The simulation results demonstrate good quantitative agreement with experimental measurements, and show the scaling relations of mean temperature and

Yi Wang; Prateep Chatterjee; John L. de Ris

2011-01-01

492

Above Water: Buoyancy & Displacement  

NSDL National Science Digital Library

In an investigation called "Shape It!" learners craft tiny boats out of clay, set them afloat on water and then add weight loads to them, in order to explore: how objects stay afloat in water; what the relationship is among surface tension, buoyancy, density and displacement; and how shape, size, and type of material affect an object's ability to remain buoyant. The introductory text discusses how heavy steel ships can float on bodies of water like rivers, bays and oceans.

Jersey, New; Center, Liberty S.; Coalition, New J.

2006-01-01

493

Rotational intermittency and turbulence induced lift experienced by large particles in a turbulent flow.  

PubMed

The motion of a large, neutrally buoyant, particle freely advected by a turbulent flow is determined experimentally. We demonstrate that both the translational and angular accelerations exhibit very wide probability distributions, a manifestation of intermittency. The orientation of the angular velocity with respect to the trajectory, as well as the translational acceleration conditioned on the spinning velocity, provides evidence of a lift force acting on the particle. PMID:21568563

Zimmermann, Robert; Gasteuil, Yoann; Bourgoin, Mickael; Volk, Romain; Pumir, Alain; Pinton, Jean-François

2011-04-15

494

The effect of different flow regimes on the growth and metabolic rates of the scleractinian coral Galaxea fascicularis  

Microsoft Academic Search

To study the effect of water flow on coral growth, four series of ten coral nubbins of Galaxea fascicularis were exposed to four different flow regimes (0, 10, 20, and 25 cm s?1, bidirectional flow) for 42 weeks. Buoyant weight, surface area, and polyp number were measured at regular intervals. Net\\u000a photosynthesis and dark respiration were measured at the corresponding flow speeds, and

M. Schutter; J. Crocker; A. J. Paijmans; M. Janse; R. Osinga; A. J. Verreth; R. H. Wijffels

2010-01-01

495

The influence of the horizontal component of the temperature gradient on nonlinear convective oscillations in two-layer systems  

NASA Astrophysics Data System (ADS)

The influence of the horizontal component of the temperature gradient on nonlinear oscillatory convective regimes, developed under the joint action of buoyant and thermocapillary effects in the 47 v2 silicone oil-water system, is investigated. Cavities with different lengths have been considered. Transitions between oscillatory flow regimes with different symmetry properties and steady flows have been studied. It is shown that under the action of the horizontal component of the temperature gradient, specific asymmetric oscillatory flow develops in the system.

Simanovskii, Ilya B.; Viviani, Antonio; Dubois, Frank; Legros, Jean-Claude

2012-10-01

496

A two-layer flow model to represent ice-ocean interactions beneath Antarctic ice shelves  

Microsoft Academic Search

We develop a two-dimensional two-layer flow model that can calculate melt rates beneath ice shelves from ocean temperature and salinity fields at the shelf front. The cavity motion is split into two layers where the upper plume layer represents buoyant meltwater-rich water rising along the underside of the ice to the shelf front, while the lower layer represents the ambient

V. Lee; A. J. Payne; J. M. Gregory

2011-01-01

497

Laminar Flow in the Ocean Ekman Layer  

NASA Astrophysics Data System (ADS)

INTRODUCTION THE EFFECT OF A STABLE DENSITY GRADIENT THE FATAL FLAW FLOW VISUALIZATION THE DISCOVERY OF LAMINAR FLOW FINE STRUCTURE WAVE-INDUCED SHEAR INSTABILITY BILLOW TURBULENCE REVERSE TRANSITION REVISED PARADIGM ONE-DIMENSIONAL MODELLING OF THE UPPER OCEAN DIURNAL VARIATION BUOYANT CONVECTION BILLOW TURBULENCE IN THE DIURNAL THERMOCLINE CONSEQUENCES FOR THE EKMAN CURRENT PROFILE SOLAR RADIATION APPLICATIONS Slippery Seas of Acapulco Pollution Afternoon Effect in Sonar Patchiness Fisheries Climate DISCUSSION CONCLUSION REFERENCES

Woods, J. T. H.

498

CO2-saturated brine reactivity at the Portland cement-shale interface and the integrity of wellbore systems  

Microsoft Academic Search

Long-term geologic storage of CO2 requires trapping the buoyant CO2 plume beneath impermeable caprocks such as shale. Given a high-quality caprock, wells that penetrate the caprock represent the most significant potential leak point in the sequestration system. This is particularly so because the Portland cement used to create the primary fluid barrier in the wellbore system is reactive with CO2

J. W. Carey; P. C. Lichtner; M. O. Wigand

2006-01-01

499

Applicability of Boussinesq approximation in a turbulent fluid with constant properties  

Microsoft Academic Search

The equations of motion describing buoyant fluids are often simplified using\\u000aa set of approximations proposed by J. Boussinesq one century ago. To resume,\\u000athey consist in assuming constant fluid properties, incompressibility and\\u000aconservation of calories during heat transport. Assuming fulfilment of the\\u000afirst requirement (constant fluid properties), we derive a set of 4 criteria\\u000afor assessing the validity of

Philippe-Emmanuel P.-E. Roche

2007-01-01

500

Purification, characterization and serological detection of virus-like particles associated with banana bunchy top disease in Australia  

Microsoft Academic Search

Isometric virus-like particles, 18 nm in diameter, have been isolated from banana (Musa spp.) affected by bunchy top disease in Australia. Banana bunchy top disease-associated virus-like particles (BBTV) banded as a single component with buoyant density of 1-28 to 1.29 g\\/ml in Cs2SO4 and sedimented at about 46S in isokinetic sucrose density gradients. The A260\\/.42S 0 of purified preparations was

John E. Thomas; Ralf G. Dietzgen

1991-01-01