Collective motion of macroscopic spheres floating on capillary ripples: Dynamic heterogeneity and dynamic criticality

NASA Astrophysics Data System (ADS)

Sanlı, Ceyda; Saitoh, Kuniyasu; Luding, Stefan; van der Meer, Devaraj

2014-09-01

When a densely packed monolayer of macroscopic spheres floats on chaotic capillary Faraday waves, a coexistence of large scale convective motion and caging dynamics typical for glassy systems is observed. We subtract the convective mean flow using a coarse graining (homogenization) method and reveal subdiffusion for the caging time scales followed by a diffusive regime at later times. We apply the methods developed to study dynamic heterogeneity and show that the typical time and length scales of the fluctuations due to rearrangements of observed particle groups significantly increase when the system approaches its largest experimentally accessible packing concentration. To connect the system to the dynamic criticality literature, we fit power laws to our results. The resultant critical exponents are consistent with those found in densely packed suspensions of colloids.

Collective motion of macroscopic spheres floating on capillary ripples: dynamic heterogeneity and dynamic criticality.

PubMed

Sanlı, Ceyda; Saitoh, Kuniyasu; Luding, Stefan; van der Meer, Devaraj

2014-09-01

When a densely packed monolayer of macroscopic spheres floats on chaotic capillary Faraday waves, a coexistence of large scale convective motion and caging dynamics typical for glassy systems is observed. We subtract the convective mean flow using a coarse graining (homogenization) method and reveal subdiffusion for the caging time scales followed by a diffusive regime at later times. We apply the methods developed to study dynamic heterogeneity and show that the typical time and length scales of the fluctuations due to rearrangements of observed particle groups significantly increase when the system approaches its largest experimentally accessible packing concentration. To connect the system to the dynamic criticality literature, we fit power laws to our results. The resultant critical exponents are consistent with those found in densely packed suspensions of colloids.

General circulation of the South Atlantic between 5 deg N and 35 deg S

NASA Technical Reports Server (NTRS)

Ollitrault, Michel; Mercier, H.; Blanc, F.; Letraon, L. Y.

1991-01-01

The TOPEX/POSEIDON altimeter will provide the temporal mean seal level. So, secondly, we propose to compute the difference between these two surfaces (mean sea level minus general circulation dynamic topography). The result will be an estimate of the marine geoid, which is time invariant for the 5-year period under consideration. If this geoid is precise enough, it will permit a description of seasonal variability of the large-scale surface circulation. If there happens to be enough float data, it may be possible to infer the first vertical modes of this variability. Thus the main goal of our investigation is to determine the 3-D general circulation of the South Atlantic and the large-scale seasonal fluctuations. This last objective, however, may be restricted to the western part of the South Atlantic because float deployments have been scheduled only in the Brasil basin.

Floating assembly of diatom Coscinodiscus sp. microshells.

PubMed

Wang, Yu; Pan, Junfeng; Cai, Jun; Zhang, Deyuan

2012-03-30

Diatoms have silica frustules with transparent and delicate micro/nano scale structures, two dimensional pore arrays, and large surface areas. Although, the diatom cells of Coscinodiscus sp. live underwater, we found that their valves can float on water and assemble together. Experiments show that the convex shape and the 40 nm sieve pores of the valves allow them to float on water, and that the buoyancy and the micro-range attractive forces cause the valves to assemble together at the highest point of water. As measured by AFM calibrated glass needles fixed in manipulator, the buoyancy force on a single floating valve may reach up to 10 μN in water. Turning the valves over, enlarging the sieve pores, reducing the surface tension of water, or vacuum pumping may cause the floating valves to sink. After the water has evaporated, the floating valves remained in their assembled state and formed a monolayer film. The bonded diatom monolayer may be valuable in studies on diatom based optical devices, biosensors, solar cells, and batteries, to better use the optical and adsorption properties of frustules. The floating assembly phenomenon can also be used as a self-assembly method for fabricating monolayer of circular plates. Copyright © 2012 Elsevier Inc. All rights reserved.

Y-MP floating point and Cholesky factorization

NASA Technical Reports Server (NTRS)

Carter, Russell

1991-01-01

The floating point arithmetics implemented in the Cray 2 and Cray Y-MP computer systems are nearly identical, but large scale computations performed on the two systems have exhibited significant differences in accuracy. The difference in accuracy is analyzed for Cholesky factorization algorithm, and it is found that the source of the difference is the subtract magnitude operation of the Cray Y-MP. The results from numerical experiments for a range of problem sizes are presented, and an efficient method for improving the accuracy of the factorization obtained on the Y-MP is presented.

The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters

PubMed Central

Suaria, Giuseppe; Avio, Carlo G.; Mineo, Annabella; Lattin, Gwendolyn L.; Magaldi, Marcello G.; Belmonte, Genuario; Moore, Charles J.; Regoli, Francesco; Aliani, Stefano

2016-01-01

The Mediterranean Sea has been recently proposed as one of the most impacted regions of the world with regards to microplastics, however the polymeric composition of these floating particles is still largely unknown. Here we present the results of a large-scale survey of neustonic micro- and meso-plastics floating in Mediterranean waters, providing the first extensive characterization of their chemical identity as well as detailed information on their abundance and geographical distribution. All particles >700 μm collected in our samples were identified through FT-IR analysis (n = 4050 particles), shedding for the first time light on the polymeric diversity of this emerging pollutant. Sixteen different classes of synthetic materials were identified. Low-density polymers such as polyethylene and polypropylene were the most abundant compounds, followed by polyamides, plastic-based paints, polyvinyl chloride, polystyrene and polyvinyl alcohol. Less frequent polymers included polyethylene terephthalate, polyisoprene, poly(vinyl stearate), ethylene-vinyl acetate, polyepoxide, paraffin wax and polycaprolactone, a biodegradable polyester reported for the first time floating in off-shore waters. Geographical differences in sample composition were also observed, demonstrating sub-basin scale heterogeneity in plastics distribution and likely reflecting a complex interplay between pollution sources, sinks and residence times of different polymers at sea. PMID:27876837

Mapping unstable manifolds using drifters/floats in a Southern Ocean field campaign

NASA Astrophysics Data System (ADS)

Shuckburgh, Emily F.

2012-09-01

Ideas from dynamical systems theory have been used in an observational field campaign in the Southern Ocean to provide information on the mixing structure of the flow. Instantaneous snapshops of data from satellite altimetry provide information concerning surface currents at a scale of 100 km or so. We show that by using time-series of satellite altimetry we are able to deduce reliable information about the structure of the surface flow at scales as small as 10 km or so. This information was used in near-real time to provide an estimate of the location of stable and unstable manifolds in the vicinity of the Antarctic Circumpolar Current. As part of a large U.K./U.S. observational field campaign (DIMES: Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) a number of drifters and floats were then released (at the surface and at a depth of approximately 1 km) close to the estimated hyperbolic point at the intersection of the two manifolds, in several locations with apparently different dynamical characteristics. The subsequent trajectories of the drifters/floats has allowed the unstable manifolds to be tracked, and the relative separation of pairs of floats has allowed an estimation of Lyapunov exponents. The results of these deployments have given insight into the strengths and limitations of the satellite data which does not resolve small scales in the velocity field, and have elucidated the transport and mixing structure of the Southern Ocean at the surface and at depth.

Understanding the recurrent large-scale green tide in the Yellow Sea: temporal and spatial correlations between multiple geographical, aquacultural and biological factors.

PubMed

Liu, Feng; Pang, Shaojun; Chopin, Thierry; Gao, Suqin; Shan, Tifeng; Zhao, Xiaobo; Li, Jing

2013-02-01

The coast of Jiangsu Province in China - where Ulva prolifera has always been firstly spotted before developing into green tides - is uniquely characterized by a huge intertidal radial mudflat. Results showed that: (1) propagules of U. prolifera have been consistently present in seawater and sediments of this mudflat and varied with locations and seasons; (2) over 50,000 tons of fermented chicken manure have been applied annually from March to May in coastal animal aquaculture ponds and thereafter the waste water has been discharged into the radial mudflat intensifying eutrophication; and (3) free-floating U. prolifera could be stranded in any floating infrastructures in coastal waters including large scale Porphyra farming rafts. For a truly integrated management of the coastal zone, reduction in nutrient inputs, and control of the effluents of the coastal pond systems, are needed to control eutrophication and prevent green tides in the future. Copyright © 2012 Elsevier Ltd. All rights reserved.

Environment parameters and basic functions for floating-point computation

NASA Technical Reports Server (NTRS)

Brown, W. S.; Feldman, S. I.

1978-01-01

A language-independent proposal for environment parameters and basic functions for floating-point computation is presented. Basic functions are proposed to analyze, synthesize, and scale floating-point numbers. The model provides a small set of parameters and a small set of axioms along with sharp measures of roundoff error. The parameters and functions can be used to write portable and robust codes that deal intimately with the floating-point representation. Subject to underflow and overflow constraints, a number can be scaled by a power of the floating-point radix inexpensively and without loss of precision. A specific representation for FORTRAN is included.

Program Correctness, Verification and Testing for Exascale (Corvette)

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

Sen, Koushik; Iancu, Costin; Demmel, James W

The goal of this project is to provide tools to assess the correctness of parallel programs written using hybrid parallelism. There is a dire lack of both theoretical and engineering know-how in the area of finding bugs in hybrid or large scale parallel programs, which our research aims to change. In the project we have demonstrated novel approaches in several areas: 1. Low overhead automated and precise detection of concurrency bugs at scale. 2. Using low overhead bug detection tools to guide speculative program transformations for performance. 3. Techniques to reduce the concurrency required to reproduce a bug using partialmore » program restart/replay. 4. Techniques to provide reproducible execution of floating point programs. 5. Techniques for tuning the floating point precision used in codes.« less

Airphoto assessment of changes in aquatic vegetation

NASA Technical Reports Server (NTRS)

Markham, B. L.; Philipson, W. R.; Russel, A. E.

1977-01-01

Large scale, multiyear, color and color infrared aerial photographs were used to evaluate changes in aquatic vegetation that have accompanied a reduction in phosphorus inputs to a phosphorus-limited, eutrophic lake in New York State. The study showed that the distribution of emergent, floating and submersed vegetation could be determined with little or no concurrent ground data; that various emergent and floating types could be separated and, with limited field checks, identified; and that different submersed types are generally not separable. Major vegetative types are characterized by spectral and nonspectral features, and a classification is developed for compiling time-sequential vegetation maps.

Finger rafting: a generic instability of floating elastic sheets.

PubMed

Vella, Dominic; Wettlaufer, J S

2007-02-23

Colliding ice floes are often observed to form a series of interlocking fingers. We show that this striking phenomenon is not a result of some peculiar property of ice but rather a general and robust mechanical phenomenon reproducible in the laboratory with other floating materials. We determine the theoretical relationship between the width of the resulting fingers and the material's mechanical properties and present experimental results along with field observations to support the theory. The generality of this "finger rafting" suggests that analogous processes may be responsible for creating the large-scale structures observed at the boundaries between Earth's convergent tectonic plates.

DUST DYNAMICS IN PROTOPLANETARY DISK WINDS DRIVEN BY MAGNETOROTATIONAL TURBULENCE: A MECHANISM FOR FLOATING DUST GRAINS WITH CHARACTERISTIC SIZES

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

Miyake, Tomoya; Suzuki, Takeru K.; Inutsuka, Shu-ichiro, E-mail: miyake.tomoya@e.mbox.nagoya-u.ac.jp, E-mail: stakeru@nagoya-u.jp

We investigate the dynamics of dust grains of various sizes in protoplanetary disk winds driven by magnetorotational turbulence, by simulating the time evolution of the dust grain distribution in the vertical direction. Small dust grains, which are well-coupled to the gas, are dragged upward with the upflowing gas, while large grains remain near the midplane of a disk. Intermediate-size grains float near the sonic point of the disk wind located at several scale heights from the midplane, where the grains are loosely coupled to the background gas. For the minimum mass solar nebula at 1 au, dust grains with sizemore » of 25–45 μm float around 4 scale heights from the midplane. Considering the dependence on the distance from the central star, smaller-size grains remain only in an outer region of the disk, while larger-size grains are distributed in a broader region. We also discuss the implications of our result for observations of dusty material around young stellar objects.« less

Correlation Lengths for Estimating the Large-Scale Carbon and Heat Content of the Southern Ocean

NASA Astrophysics Data System (ADS)

Mazloff, M. R.; Cornuelle, B. D.; Gille, S. T.; Verdy, A.

2018-02-01

The spatial correlation scales of oceanic dissolved inorganic carbon, heat content, and carbon and heat exchanges with the atmosphere are estimated from a realistic numerical simulation of the Southern Ocean. Biases in the model are assessed by comparing the simulated sea surface height and temperature scales to those derived from optimally interpolated satellite measurements. While these products do not resolve all ocean scales, they are representative of the climate scale variability we aim to estimate. Results show that constraining the carbon and heat inventory between 35°S and 70°S on time-scales longer than 90 days requires approximately 100 optimally spaced measurement platforms: approximately one platform every 20° longitude by 6° latitude. Carbon flux has slightly longer zonal scales, and requires a coverage of approximately 30° by 6°. Heat flux has much longer scales, and thus a platform distribution of approximately 90° by 10° would be sufficient. Fluxes, however, have significant subseasonal variability. For all fields, and especially fluxes, sustained measurements in time are required to prevent aliasing of the eddy signals into the longer climate scale signals. Our results imply a minimum of 100 biogeochemical-Argo floats are required to monitor the Southern Ocean carbon and heat content and air-sea exchanges on time-scales longer than 90 days. However, an estimate of formal mapping error using the current Argo array implies that in practice even an array of 600 floats (a nominal float density of about 1 every 7° longitude by 3° latitude) will result in nonnegligible uncertainty in estimating climate signals.

Scrap tyre recycling process with molten zinc as direct heat transfer and solids separation fluid: A new reactor concept.

PubMed

Riedewald, Frank; Goode, Kieran; Sexton, Aidan; Sousa-Gallagher, Maria J

2016-01-01

Every year about 1.5 billion tyres are discarded worldwide representing a large amount of solid waste, but also a largely untapped source of raw materials. The objective of the method was to prove the concept of a novel scrap tyre recycling process which uses molten zinc as the direct heat transfer fluid and, simultaneously, uses this media to separate the solids products (i.e. steel and rCB) in a sink-float separation at an operating temperature of 450-470 °C. This methodology involved: •construction of the laboratory scale batch reactor,•separation of floating rCB from the zinc,•recovery of the steel from the bottom of the reactor following pyrolysis.

Floating Collection in an Academic Library: An Audacious Experiment That Succeeded

ERIC Educational Resources Information Center

Coopey, Barbara; Eshbach, Barbara; Notartomas, Trish

2016-01-01

Can a floating collection thrive in a large multicampus academic research library? Floating collections have been successful in public libraries for some time, but it is uncommon for academic libraries and unheard of for a large academic library system. This article will discuss the investigation into the feasibility of a floating collection at…

Comparative evaluation of single and bilayered lamotrigine floating tablets

PubMed Central

Lakshmi, PK; Sridhar, M; Shruthi, B

2013-01-01

Aim: The purpose of this study was to prepare lamotrigine (LM) bilayered and single layered floating tablets and to compare their release profiles. Materials and Methods: LM floating tablets were prepared by direct compression method. Drug, hydroxy propyl methyl cellulose K4M, lactose monohydrate and polyvinylpyrrolidone K30 constitute controlled release layer components and floating layer components includes polymers and sodium bicarbonate. The prepared tablets were evaluated for physicochemical parameters such as hardness, friability, weight variation, thickness, floating lag time (FLT), floating time, in vitro buoyancy study, in vitro release studies. The drug-polymer interaction was studied by fourier transform infrared and differential scanning calorimetry. Results and Discussion: The FLT of all the formulations were within the prescribed limits (<3 min). When ethyl cellulose was used as floating layer component, tablets showed good buoyancy effect but eroded within 6-8 h. Hence it was replaced with hydroxypropyl cellulose -M hydrophilic polymer, which showed good FLT and floating duration for 16 h. Formulation LFC4 was found to be optimized with dissolution profile of zero order kinetics showing fickian diffusion. A comparative study of bilayered and single layered tablets of LM showed a highest similarity factor of 83.03, difference factor of 2.74 and t-test (P < 0.05) indicates that there is no significant difference between them. Conclusion: Though bilayered tablet possess many advantages, single layered tablet would be economical, cost-effective and reproducible for large scale production in the industry. However, the results of present study demonstrated that the in vitro development of bilayered gastro retentive floating tablets with controlled drug release profile for LM is feasible. PMID:24167788

ROStoJAUSBridge Manual

DTIC Science & Technology

2012-03-01

Description A dass that handles Imming the JAUS header pmUon of JAUS messages. jaus_hmd~_msg is included as a data member in all JAUS messages. Member...scaleTolnt16 (float val, float low, float high) [related] Scales signed short value val, which is bounded by low and high. Shifts the center point of low...and high to zero, and shifts val accordingly. V a! is then up scaled by the ratio of the range of short values to the range of values from high to low

Large-scale environmental degradation results in inequitable impacts to already impoverished communities: A case study from the floating villages of Cambodia.

PubMed

Althor, Glenn; Mahood, Simon; Witt, Bradd; Colvin, Rebecca M; Watson, James E M

2018-02-19

Cambodian subsistence communities within the Tonle Sap Great Lake area rely on resource extraction from the lake to meet livelihood needs. These fishing communities-many of which consist of dwellings floating on the lake-face potentially profound livelihood challenges because of climate change and changing hydrology due to dam construction for hydroelectricity within the Mekong Basin. We conducted interviews across five village communities, with local subsistence fisher people in the Tonle Sap in 2015, and used thematic analysis methods to reveal a fishery system that is undergoing rapid ecological decline, with local fishing communities increasingly experiencing reductions in available fish stocks. As a result, over 100 000 people living in these communities are experiencing a direct loss of well-being and livelihood. We discuss these losses and consider their implications for the future viability of Cambodian floating village communities.

A novel grounded to floating admittance converter with electronic control

NASA Astrophysics Data System (ADS)

Prasad, Dinesh; Ahmad, Javed; Srivastava, Mayank

2018-01-01

This article suggests a new grounded to floating admittance convertor employing only two voltage differencing transconductance amplifiers (VDTAs). The proposed circuit can convert any arbitrary grounded admittance into floating admittance with electronically controllable scaling factor. The presented converter enjoys the following beneficial: (1) no requirement of any additional passive element (2) scaling factor can be tuned electronically through bias currents of VDTAs (3) no matching constraint required (4) low values of active/passive sensitivity indexes and (5) excellent non ideal behavior that indicates no deviation in circuit behavior even under non ideal environment. Application of the proposed configuration in realization of floating resistor and floating capacitor has been presented and the workability of these floating elements has been confirmed by active filter design examples. SPICE simulations have been performed to demonstrate the performance of the proposed circuits.

[Analysis of self-rated health status of the floating population in a district of Guangzhou].

PubMed

Duan, Jun-Jie; Wang, Dong; Nie, Jun

2008-06-01

To investigate the self-rated health status of the floating population in a district of Guangzhou. Cluster stratified random sampling was applied to survey 219 floating people from a community in Guangzhou, who were assessed with self-rated health status was assessed with Self-Rated Health Measurement Scale. The scores of the floating population were significantly higher than the normal individuals in physical health sub-scales (P<0.01), while the scores of the floating population were significantly lower in psychological and social health sub-scales (P<0.05). The low score items in the subscale of physical health mainly consisted of fatigue and gastrointestinal symptoms, those in the subscale of psychological health mainly in anxiety, depression and obsession, and those in the subscale of social health mainly in participation in social activities and seeking help from others. To improve the health status of the floating population, campaigns of health education need to be launched periodically and psychological counseling should be provided for these individuals. Additionally, interactive activities should be increased in their daily social life.

Floating Data and the Problem with Illustrating Multiple Regression.

ERIC Educational Resources Information Center

Sachau, Daniel A.

2000-01-01

Discusses how to introduce basic concepts of multiple regression by creating a large-scale, three-dimensional regression model using the classroom walls and floor. Addresses teaching points that should be covered and reveals student reaction to the model. Finds that the greatest benefit of the model is the low fear, walk-through, nonmathematical…

Networks of triboelectric nanogenerators for harvesting water wave energy: a potential approach toward blue energy.

PubMed

Chen, Jun; Yang, Jin; Li, Zhaoling; Fan, Xing; Zi, Yunlong; Jing, Qingshen; Guo, Hengyu; Wen, Zhen; Pradel, Ken C; Niu, Simiao; Wang, Zhong Lin

2015-03-24

With 70% of the earth's surface covered with water, wave energy is abundant and has the potential to be one of the most environmentally benign forms of electric energy. However, owing to lack of effective technology, water wave energy harvesting is almost unexplored as an energy source. Here, we report a network design made of triboelectric nanogenerators (TENGs) for large-scale harvesting of kinetic water energy. Relying on surface charging effect between the conventional polymers and very thin layer of metal as electrodes for each TENG, the TENG networks (TENG-NW) that naturally float on the water surface convert the slow, random, and high-force oscillatory wave energy into electricity. On the basis of the measured output of a single TENG, the TENG-NW is expected to give an average power output of 1.15 MW from 1 km(2) surface area. Given the compelling features, such as being lightweight, extremely cost-effective, environmentally friendly, easily implemented, and capable of floating on the water surface, the TENG-NW renders an innovative and effective approach toward large-scale blue energy harvesting from the ocean.

Floating Offshore Wind in California: Gross Potential for Jobs and Economic Impacts from Two Future Scenarios

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

Speer, Bethany; Keyser, David; Tegen, Suzanne

Construction of the first offshore wind farm in the United States began in 2015, using fixed platform structures that are appropriate for shallow seafloors, like those located off of the East Coast and mid-Atlantic. However, floating platforms, which have yet to be deployed commercially, will likely need to anchor to the deeper seafloor if deployed off of the West Coast. To analyze the employment and economic potential for floating offshore wind along the West Coast, the Bureau of Ocean Energy Management (BOEM) has commissioned the National Renewable Energy Laboratory (NREL) to analyze two hypothetical, large-scale deployment scenarios for California: 16more » GW of offshore wind by 2050 (Scenario A) and 10 GW of offshore wind by 2050 (Scenario B). The results of this analysis can be used to better understand the general scales of economic opportunities that could result from offshore wind development. Results show total state gross domestic product (GDP) impacts of $16.2 billion in Scenario B or $39.7 billion in Scenario A for construction; and $3.5 billion in Scenario B or $7.9 billion in Scenario A for the operations phases.« less

Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland

NASA Astrophysics Data System (ADS)

Burger, Magdalena; Berger, Sina; Spangenberg, Ines; Blodau, Christian

2016-06-01

Ponds smaller than 10 000 m2 likely account for about one-third of the global lake perimeter. The release of methane (CH4) and carbon dioxide (CO2) from these ponds is often high and significant on the landscape scale. We measured CO2 and CH4 fluxes in a temperate peatland in southern Ontario, Canada, in summer 2014 along a transect from the open water of a small pond (847 m2) towards the surrounding floating mat (5993 m2) and in a peatland reference area. We used a high-frequency closed chamber technique and distinguished between diffusive and ebullitive CH4 fluxes. CH4 fluxes and CH4 bubble frequency increased from a median of 0.14 (0.00 to 0.43) mmol m-2 h-1 and 4 events m-2 h-1 on the open water to a median of 0.80 (0.20 to 14.97) mmol m-2 h-1 and 168 events m-2 h-1 on the floating mat. The mat was a summer hot spot of CH4 emissions. Fluxes were 1 order of magnitude higher than at an adjacent peatland site. During daytime the pond was a net source of CO2 equivalents to the atmosphere amounting to 0.13 (-0.02 to 1.06) g CO2 equivalents m-2 h-1, whereas the adjacent peatland site acted as a sink of -0.78 (-1.54 to 0.29) g CO2 equivalents m-2 h-1. The photosynthetic CO2 uptake on the floating mat did not counterbalance the high CH4 emissions, which turned the floating mat into a strong net source of 0.21 (-0.11 to 2.12) g CO2 equivalents m-2 h-1. This study highlights the large small-scale variability of CH4 fluxes and CH4 bubble frequency at the peatland-pond interface and the importance of the often large ecotone areas surrounding small ponds as a source of greenhouse gases to the atmosphere.

Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland

NASA Astrophysics Data System (ADS)

Blodau, Christian; Burger, Magdalena; Berger, Sina; Spangenberg, Ines

2016-04-01

Ponds smaller than 10000 m2 likely account for about one third of the global lake perimeter. The release of methane (CH4) and carbon dioxide (CO2) from these ponds is often high and significant on the landscape scale. We measured CO2 and CH4 fluxes in a temperate peatland in southern Ontario, Canada, in summer 2014 along a transect from the open water of a small pond (847 m2) towards the surrounding floating mat (5993 m2) and in a peatland reference area. We used a high-frequency closed chamber technique and distinguished between diffusive and ebullitive CH4 fluxes. CH4 fluxes and CH4 bubble frequency increased from a median of 0.14 (0.00 to 0.43) mmol m-2 h-1 and 4 events m-2 h-1 on the open water to a median of 0.80 (0.20 to 14.97) mmol m-2 h-1 and 168 events m-2 h-1 on the floating mat. The mat was a summer hot spot of CH4 emissions. Fluxes were one order of magnitude higher than at an adjacent peatland site. During daytime the pond was a net source of CO2 equivalents to the atmosphere amounting to 0.13 (-0.02 to 1.06) g CO2 equivalents m-2 h-1, whereas the adjacent peatland site acted as a sink of -0.78 (-1.54 to 0.29) g CO2 equivalents m-2 h-1. The photosynthetic CO2 uptake on the floating mat did not counterbalance the high CH4 emissions, which turned the floating mat into a strong net source of 0.21 (-0.11 to 2.12) g CO2 equivalents m-2 h-1. This study highlights the large small-scale variability of CH4 fluxes and CH4 bubble frequency at the peatland-pond interface and the importance of the often large ecotone areas surrounding small ponds as a source of greenhouse gases to the atmosphere.

Evaporation suppression from reservoirs using floating covers: Lab scale wind-tunnel observations and mechanistic model predictions

NASA Astrophysics Data System (ADS)

Or, Dani; Lehmann, Peter; Aminzadeh, Milad; Sommer, Martina; Wey, Hannah; Krentscher, Christiane; Wunderli, Hans; Breitenstein, Daniel

2017-04-01

The competition over dwindling fresh water resources is expected to intensify with projected increase in human population in arid regions, expansion of irrigated land and changes in climate and drought patterns. The volume of water stored in reservoirs would also increase to mitigate seasonal shortages due to rainfall variability and to meet irrigation water needs. By some estimates up to half of the stored water is lost to evaporation, thereby exacerbating the water scarcity problem. Recently, there is an upsurge in the use of self-assembling floating covers to suppress evaporation, yet the design and implementation remain largely empirical. We report a systematic experimental evaluation of different cover types and external drivers (radiation, wind, wind plus radiation) on evaporation suppression and energy balance of a 1.4 m2 basin placed in a wind-tunnel. Surprisingly, evaporation suppression by black and white floating covers (balls and plates) were similar despite significantly different energy balance regimes over the cover surfaces. Moreover, the evaporation suppression efficiency was a simple function of the uncovered area (square root of the uncovered fraction) with linear relations with the covered area in some cases. The thermally decoupled floating covers offer an efficient solution to the evaporation suppression with limited influence of the surface energy balance (water temperature for black and white covers was similar and remained nearly constant). The results will be linked with a predictive evaporation-energy balance model and issues of spatial scales and long exposure times will be studied.

Convection of wall shear stress events in a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Pabon, Rommel; Mills, David; Ukeiley, Lawrence; Sheplak, Mark

2017-11-01

The fluctuating wall shear stress is measured in a zero pressure gradient turbulent boundary layer of Reτ 1700 simultaneously with velocity measurements using either hot-wire anemometry or particle image velocimetry. These experiments elucidate the patterns of large scale structures in a single point measurement of the wall shear stress, as well as their convection velocity at the wall. The wall shear stress sensor is a CS-A05 one-dimensional capacitice floating element from Interdisciplinary Consulting Corp. It has a nominal bandwidth from DC to 5 kHz and a floating element size of 1 mm in the principal sensing direction (streamwise) and 0.2 mm in the cross direction (spanwise), allowing the large scales to be well resolved in the current experimental conditions. In addition, a two sensor array of CS-A05 aligned in the spanwise direction with streamwise separations O (δ) is utilized to capture the convection velocity of specific scales of the shear stress through a bandpass filter and peaks in the correlation. Thus, an average wall normal position for the corresponding convecting event can be inferred at least as high as the equivalent local streamwise velocity. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138.

Determination of the State of Strain of Large Floating Covers Using Unmanned Aerial Vehicle (UAV) Aided Photogrammetry

PubMed Central

Ong, Wern Hann; Chiu, Wing Kong; Kuen, Thomas; Kodikara, Jayantha

2017-01-01

Floating covers used in waste water treatment plants are one of the many structures formed with membrane materials. These structures are usually large and can spread over an area measuring 470 m × 170 m. The aim of this paper is to describe recent work to develop an innovative and effective approach for structural health monitoring (SHM) of such large membrane-like infrastructure. This paper will propose a potentially cost-effective non-contact approach for full-field strain and stress mapping using an unmanned aerial vehicle (UAV) mounted with a digital camera and a global positioning system (GPS) tracker. The aim is to use the images acquired by the UAV to define the geometry of the floating cover using photogrammetry. In this manner, any changes in the geometry of the floating cover due to forces acting beneath resulting from its deployment and usage can be determined. The time-scale for these changes is in terms of weeks and months. The change in the geometry can be implemented as input conditions to a finite element model (FEM) for stress prediction. This will facilitate the determination of the state of distress of the floating cover. This paper investigates the possibility of using data recorded from a UAV to predict the strain level and assess the health of such structures. An investigation was first conducted on a laboratory sized membrane structure instrumented with strain gauges for comparison against strains, which were computed from 3D scans of the membrane geometry. Upon validating the technique in the laboratory, it was applied to a more realistic scenario: an outdoor test membrane structure and capable UAV were constructed to see if the shape of the membrane could be computed. The membrane displacements were then used to calculate the membrane stress and strain, state demonstrating a new way to perform structural health monitoring on membrane structures. PMID:28788081

Determination of the State of Strain of Large Floating Covers Using Unmanned Aerial Vehicle (UAV) Aided Photogrammetry.

PubMed

Ong, Wern Hann; Chiu, Wing Kong; Kuen, Thomas; Kodikara, Jayantha

2017-07-28

Floating covers used in waste water treatment plants are one of the many structures formed with membrane materials. These structures are usually large and can spread over an area measuring 470 m × 170 m. The aim of this paper is to describe recent work to develop an innovative and effective approach for structural health monitoring (SHM) of such large membrane-like infrastructure. This paper will propose a potentially cost-effective non-contact approach for full-field strain and stress mapping using an unmanned aerial vehicle (UAV) mounted with a digital camera and a global positioning system (GPS) tracker. The aim is to use the images acquired by the UAV to define the geometry of the floating cover using photogrammetry. In this manner, any changes in the geometry of the floating cover due to forces acting beneath resulting from its deployment and usage can be determined. The time-scale for these changes is in terms of weeks and months. The change in the geometry can be implemented as input conditions to a finite element model (FEM) for stress prediction. This will facilitate the determination of the state of distress of the floating cover. This paper investigates the possibility of using data recorded from a UAV to predict the strain level and assess the health of such structures. An investigation was first conducted on a laboratory sized membrane structure instrumented with strain gauges for comparison against strains, which were computed from 3D scans of the membrane geometry. Upon validating the technique in the laboratory, it was applied to a more realistic scenario: an outdoor test membrane structure and capable UAV were constructed to see if the shape of the membrane could be computed. The membrane displacements were then used to calculate the membrane stress and strain, state demonstrating a new way to perform structural health monitoring on membrane structures.

Killer whales and whaling: the scavenging hypothesis.

PubMed

Whitehead, Hal; Reeves, Randall

2005-12-22

Killer whales (Orcinus orca) frequently scavenged from the carcasses produced by whalers. This practice became especially prominent with large-scale mechanical whaling in the twentieth century, which provided temporally and spatially clustered floating carcasses associated with loud acoustic signals. The carcasses were often of species of large whale preferred by killer whales but that normally sink beyond their diving range. In the middle years of the twentieth century floating whaled carcasses were much more abundant than those resulting from natural mortality of whales, and we propose that scavenging killer whales multiplied through diet shifts and reproduction. During the 1970s the numbers of available carcasses fell dramatically with the cessation of most whaling (in contrast to a reasonably stable abundance of living whales), and the scavenging killer whales needed an alternative source of nutrition. Diet shifts may have triggered declines in other prey species, potentially affecting ecosystems, as well as increasing direct predation on living whales.

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

Rehder, J.B.

The project focuses on an appropriate technology for small-scale hydro power: floating waterwheels and turbines. For background, relic and existing systems such as early floating mills, traditional Amish waterwheels, and micro-hydro systems are examined. In the design phase of the project, new designs for Floating Hydro Power Systems include: an analysis of floatation materials and systems; a floating undershot waterwheel design; a floating cylinder (fiberglass storage tank) design; a submerged tube design; and a design for a floating platform with submerged propellers. Finally, in the applications phase, stream flow data from East Tennessee streams are used in a discussion ofmore » the potential applications of floating hydro power systems in small streams.« less

Floating Offshore Wind in Oregon: Potential for Jobs and Economic Impacts in Oregon Coastal Counties from Two Future Scenarios

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

Jimenez, Tony; Keyser, David; Tegen, Suzanne

This analysis examines the employment and potential economic impacts of large-scale deployment of offshore wind technology off the coast of Oregon. This analysis examines impacts within the seven Oregon coastal counties: Clatsop, Tillamook, Lincoln, Lane, Douglas, Coos, and Curry. The impacts highlighted here can be used in county, state, and regional planning discussions and can be scaled to get a general sense of the economic development opportunities associated with other deployment scenarios.

OTEC Cold Water Pipe-Platform Subsystem Dynamic Interaction Validation

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

Varley, Robert; Halkyard, John; Johnson, Peter

A commercial floating 100-megawatt (MW) ocean thermal energy conversion (OTEC) power plant will require a cold water pipe (CWP) with a diameter of 10-meter (m) and length of up to 1,000 m. The mass of the cold water pipe, including entrained water, can exceed the mass of the platform supporting it. The offshore industry uses software-modeling tools to develop platform and riser (pipe) designs to survive the offshore environment. These tools are typically validated by scale model tests in facilities able to replicate real at-sea meteorological and ocean (metocean) conditions to provide the understanding and confidence to proceed to finalmore » design and full-scale fabrication. However, today’s offshore platforms (similar to and usually larger than those needed for OTEC applications) incorporate risers (or pipes) with diameters well under one meter. Secondly, the preferred construction method for large diameter OTEC CWPs is the use of composite materials, primarily a form of fiber-reinforced plastic (FRP). The use of these material results in relatively low pipe stiffness and large strains compared to steel construction. These factors suggest the need for further validation of offshore industry software tools. The purpose of this project was to validate the ability to model numerically the dynamic interaction between a large cold water-filled fiberglass pipe and a floating OTEC platform excited by metocean weather conditions using measurements from a scale model tested in an ocean basin test facility.« less

Modelling the transport and accumulation of floating marine debris in the Mediterranean basin.

PubMed

Mansui, J; Molcard, A; Ourmières, Y

2015-02-15

In the era of plastic and global environmental issues, when large garbage patches have been observed in the main oceanic basins, this work is the first attempt to explore the possibility that similar permanent accumulation structures may exist in the Mediterranean Sea. The questions addressed in this work are: can the general circulation, with its sub-basins scale gyres and mesoscale instabilities, foster the concentration of floating items in some regions? Where are the more likely coastal zones impacted from open ocean sources? Multi-annual simulations of advected surface passive debris depict the Tyrrhenian Sea, the north-western Mediterranean sub-basin and the Gulf of Sirte as possible retention areas. The western Mediterranean coasts present very low coastal impact, while the coastal strip from Tunisia to Syria appears as the favourite destination. No permanent structure able to retain floating items in the long-term were found, as the basin circulation variability brings sufficient anomalies. Copyright © 2014 Elsevier Ltd. All rights reserved.

An array processing system for lunar geochemical and geophysical data

NASA Technical Reports Server (NTRS)

Eliason, E. M.; Soderblom, L. A.

1977-01-01

A computerized array processing system has been developed to reduce, analyze, display, and correlate a large number of orbital and earth-based geochemical, geophysical, and geological measurements of the moon on a global scale. The system supports the activities of a consortium of about 30 lunar scientists involved in data synthesis studies. The system was modeled after standard digital image-processing techniques but differs in that processing is performed with floating point precision rather than integer precision. Because of flexibility in floating-point image processing, a series of techniques that are impossible or cumbersome in conventional integer processing were developed to perform optimum interpolation and smoothing of data. Recently color maps of about 25 lunar geophysical and geochemical variables have been generated.

Self-assembled diatom substrates with plasmonic functionality

NASA Astrophysics Data System (ADS)

Kwon, Sun Yong; Park, Sehyun; Nichols, William T.

2014-04-01

Marine diatoms have an exquisitely complex exoskeleton that is promising for engineered surfaces such as sensors and catalysts. For such applications, creating uniform arrays of diatom frustules across centimeter scales will be necessary. Here, we present a simple, low-cost floating interface technique to self-assemble the diatom frustules. We show that well-prepared diatoms form floating hexagonal close-packed arrays at the air-water interface that can be transferred directly to a substrate. We functionalize the assembled diatom surfaces with gold and characterize the plasmonic functionality by using surface enhanced Raman scattering (SERS). Thin gold films conform to the complex, hierarchical diatom structure and produce a SERS enhancement factor of 2 × 104. Small gold nanoparticles attached to the diatom's surface produce a higher enhancement of 7 × 104 due to stronger localization of the surface plasmons. Taken together, the large-scale assembly and plasmonic functionalization represent a promising platform to control the energy and the material flows at a complex surface for applications such as sensors and plasmonic enhanced catalysts.

[Treatment of Persistent Somatoform Pain Disorder by Floating Needle Therapy and Duloxetine].

PubMed

Ren, Wan-wen; Zhou, Zhi-ying; Xu, Mi-mi; Long, Sen; Tang, Guang-zheng; Mao, Hong-jing; Chen, Shu-lin

2016-02-01

To evaluate clinical effect and safety of floating needle therapy and duloxetine in treating patients with persistent somatoform pain disorder (PSPD). Totally 108 PSPD patients were randomly assigned to the floating needle treatment group, the duloxetine treatment group, and the placebo treatment group, 36 in each group. Patients in the floating needle treatment group received floating needle therapy and placebo. Those in the duloxetine treatment group received duloxetine and simulated floating needle therapy. Those in the placebo treatment group received the placebo and simulated floating needle therapy. All treatment lasted for six weeks. Efficacy and adverse reactions were evaluated using Simple McGill pain scale (SF-MPQ) and Treatment Emergent Symptom Scale (TESS) before treatment and immediately after treatment, as well as at the end of 1st, 2nd, 4th, and 6th week of treatment, respectively. Hamilton Depression Scale (HAMD, 17 items), Hamilton Anxiety Scale (HAMA) were assessed before treatment and at the end of 1st, 2nd, 4th, and 6th week of treatment, respectively. Patients in the floating needle treatment group and the duloxetine treatment group with the total reducing score rate of SF-MPQ in Pain Rating index (PRI) ≥ 50% after 6 weeks' treatment were involved in the follow-up study. (1) Compared with the same group before treatment, SF-MPQ score, HAMD score and HAMA total scores all decreased in all the three groups at the end of 1st, 2nd, 4th, and 6th week of treatment (P < 0.05, P < 0.01). Besides , each item of SF-MPQ significantly decreased immediately after treatment in the floating needle treatment group (P < 0.01). Compared with the placebo treatment group, SF-MPQ, HAMD, and HAMA total score in the floating needle treatment group significantly decreased after 1, 2, 4, and 6 weeks of treatment (P < 0.05, P < 0.01). SF-MPQ score, HAMD score and HAMA total score in the duloxetine treatment group also significantly decreased after 2, 4, and 6 weeks of treatment (P < 0.05, P < 0.01). (2) There were 3 patients (8.3%) who had adverse reactions in the floating needle treatment group, 17 (50.0%) in the duloxetine treatment group, and 7 (21.2%) in the placebo treatment group. Compared with the placebo treatment group, the incidence of adverse reaction increased in the duloxetine treatment group (χ² = 6.04, P < 0.05). Besides, it was higher in the duloxetine treatment group than in the floating needle treatment group (χ² = 14.9, P < 0.05). (3) There were 19 patients in the floating needle treatment group and 17 patients in the duloxetine treatment group involved in the follow-up study. Compared with 6 weeks after treatment, no significant difference was observed at 3 and 6 months after treatment in the score of SF-MPQ, HAMD, and HAMA in the floating needle treatment group and the duloxetine treatment group. No significant difference was observed between the two groups (P > 0.05). There were 5 patients (29.4%) who had adverse reactions in the duloxetine treatment group, and no adverse reactions were observed in the floating needle treatment group. The adverse reaction rate was significantly different between the two groups (χ² = 4.26, P < 0.05). Floating needle therapy and duloxetine were effective in treatment of patients with PSPD. However, floating needle therapy could relieve pain more rapidly than duloxetine, with obviously less adverse reactions.

Cheerios Effect Controlled by Electrowetting.

PubMed

Yuan, Junqi; Feng, Jian; Cho, Sung Kwon

2015-08-04

The Cheerios effect is a common phenomenon in which small floating objects are either attracted or repelled by the sidewall due to capillary interaction. This attractive or repulsive behavior is highly dependent on the slope angles (angles of the interface on the wall or floating object with respect to a horizontal line) that can be mainly controlled by the wettability of the wall and floating object and the density of the object. In this paper, electrowetting on dielectric (EWOD) is implemented to the wall or floating object in order to actively control the wettability and thus capillary interaction. As such, the capillary force on buoyant and dense floating objects can be easily switched between repulsion and attraction by simply applying an electrical input. In addition, the theoretical prediction for the capillary force is verified experimentally by measuring the motion of floating particle and the critical contact angle on the wall at which the capillary force changes from attraction to repulsion. This successive verification is enabled by the merit of EWOD that allows for continuous change in the contact angle. Finally, the control method is extended to continuously move a floating object along a linear path and to continuously rotate a dumbbell-like floating object in centimeter scales using arrays of EWOD electrodes. A continuous linear motion is also accomplished in a smaller scale where the channel width (3 mm) is comparable to the capillary length.

Damage identification of a TLP floating wind turbine by meta-heuristic algorithms

NASA Astrophysics Data System (ADS)

Ettefagh, M. M.

2015-12-01

Damage identification of the offshore floating wind turbine by vibration/dynamic signals is one of the important and new research fields in the Structural Health Monitoring (SHM). In this paper a new damage identification method is proposed based on meta-heuristic algorithms using the dynamic response of the TLP (Tension-Leg Platform) floating wind turbine structure. The Genetic Algorithms (GA), Artificial Immune System (AIS), Particle Swarm Optimization (PSO), and Artificial Bee Colony (ABC) are chosen for minimizing the object function, defined properly for damage identification purpose. In addition to studying the capability of mentioned algorithms in correctly identifying the damage, the effect of the response type on the results of identification is studied. Also, the results of proposed damage identification are investigated with considering possible uncertainties of the structure. Finally, for evaluating the proposed method in real condition, a 1/100 scaled experimental setup of TLP Floating Wind Turbine (TLPFWT) is provided in a laboratory scale and the proposed damage identification method is applied to the scaled turbine.

Preliminary results from DIMES: Dispersion in the ACC

NASA Astrophysics Data System (ADS)

Balwada, D.; Speer, K.; LaCasce, J. H.; Owens, B.

2012-04-01

The Diapycnal and Isopynal Mixing Experiment in the Southern Ocean (DIMES) is a CLIVAR process study designed to study mixing in the Antarctic Circumpolar Current. The experiment includes tracer release, float, and small-scale turbulence components. This presentation will report on some results of the float component, from floats deployed across the ACC in the Southeast Pacific Ocean. These are the first subsurface Lagrangian trajectories from the ACC. Floats were deployed to follow approximately a constant density surface for a period of 1-3 years. To help aid the experimental results virtual floats were advected using AVISO data and basic statistics were derived from both deployed and virtual float trajectories. Experimental design, initial results, comparison to virtual floats and single particle and relative dispersion calculations will be presented.

Can we reconstruct mean and eddy fluxes from Argo floats?

NASA Astrophysics Data System (ADS)

Chapman, Christopher; Sallée, Jean-Baptiste

2017-12-01

The capacity of deep velocity estimates provided by the Argo float array to reconstruct both mean and eddying quantities, such as the heat flux, is addressed using an idealized eddy resolving numerical model, designed to be representative of the Southern Ocean. The model is seeded with 450 "virtual" Argo floats, which are then advected by the model fields for 10 years. The role of temporal sampling, array density and length of the float experiment are then systematically investigated by comparing the reconstructed velocity, eddy kinetic energy and heat-flux from the virtual Argo floats with the "true" values from the model output. We find that although errors in all three quantities decrease with increasing temporal sampling rate, number of floats and experiment duration, the error approaches an asymptotic limit. Thus, as these parameters exceed this limit, only marginal reductions in the error are observed. The parameters of the real Argo array, when scaled to match those of the virtual Argo array, generally fall near to, or within, the asymptotic region. Using the numerical model, a method for the calculation of cross-stream heat-fluxes is demonstrated. This methodology is then applied to 5 years of Argo derived velocities using the ANDRO dataset of Ollitrault & Rannou (2013) in order to estimate the eddy heat flux at 1000m depth across the Polar Front in the Southern Ocean. The heat-flux is concentrated in regions downstream of large bathymetric features, consistent with the results of previous studies. 2 ± 0.5 TW of heat transport across the Polar Front at this depth is found, with more than 90% of that total concentrated in less than 20% of the total longitudes spanned by the front. Finally, the implications of this work for monitoring the ocean climate are discussed.

Psycho-biological correlates of free-floating anxiety symptoms in male patients with sexual dysfunctions.

PubMed

Corona, Giovanni; Mannucci, Edoardo; Petrone, Luisa; Ricca, Valdo; Balercia, Giancarlo; Giommi, Roberta; Forti, Gianni; Maggi, Mario

2006-01-01

Anxiety has a relevant impact on everyday life, including sexual life, and therefore is considered the final common pathway by which social, psychological, and biological stressors negatively affect sexual functioning. The aim of this study is to define the psycho-biological correlates of free-floating anxiety in a large sample of patients complaining of erectile dysfunction (ED)-based sexual problems. We studied a consecutive series of 882 ED patients using SIEDY, a 13-item structured interview, composed of 3 scales that identify and quantify organic, relational, and intrapsychic domains. MHQ-A scoring from Middlesex Hospital Questionnaire (MHQ) was used as a putative marker of free-floating anxiety symptoms (AS). Metabolic and hormonal parameters, nocturnal penile tumescence (NPT) test, and penile Doppler ultrasound (PDU) examination were also performed. MHQ-A score was significantly higher in patients complaining of difficulties in maintaining erection and in those reporting premature ejaculation (6.5 +/- 3.3 vs 5.8 +/- 3.3 and 6.6 +/- 3.3 vs 6.1 +/- 3.3, respectively; both P < .05). Moreover, ASs were significantly correlated to life stressors quantified by SIEDY scale 2 (relational component) and scale 3 (intrapsychic component) scores, as dissatisfaction at work or within the family or couple relationships. Among physical, biochemical, or instrumental parameters tested, only end-diastolic velocity at PDU was significantly (P < .05) related to ASs. In conclusion, in patients with ED-based sexual problems, ASs are correlated to many relational and life stressors. Conversely, organic problems are not necessarily associated with MHQ-A score.

Evaporation suppression from water reservoirs using floating covers: Lab scale observations and model predictions

NASA Astrophysics Data System (ADS)

Or, D.; Lehmann, P.; Aminzadeh, M.; Sommer, M.; Wey, H.; Wunderli, H.; Breitenstein, D.

2016-12-01

The competition over dwindling fresh water resources is expected to intensify with projected increase in human population in arid regions, expansion of irrigated land and changes in climate and drought patterns. The volume of water stored in reservoirs would also increase to mitigate seasonal shortages due to rainfall variability and to meet irrigation water needs. By some estimates up to half of the stored water is lost to evaporation thereby exacerbating the water scarcity problem. Recently, there is an upsurge in the use of self-assembling floating covers to suppress evaporation, yet the design, and implementation remain largely empirical. Studies have shown that evaporation suppression is highly nonlinear, as also known from a century of research on gas exchange from plant leaves (that often evaporate as free water surfaces through stomata that are only 1% of leaf area). We report a systematic evaluation of different cover types and external drivers (radiation, wind, wind+radiation) on evaporation suppression and energy balance of a 1.4 m2 basin placed in a wind-tunnel. Surprisingly, evaporation suppression by black and white floating covers (balls and plates) were similar despite significantly different energy balance regimes over the cover surfaces. Moreover, the evaporation suppression efficiency was a simple function of the uncovered area (square root of the uncovered fraction) with linear relations with the covered area in some cases. The thermally decoupled floating covers offer an efficient solution to the evaporation suppression with limited influence of the surface energy balance (water temperature for black and white covers was similar and remained nearly constant). The results will be linked with a predictive evaporation-energy balance model and issues of spatial scales and long exposure times will be studied.

Plastic debris in the open ocean

PubMed Central

Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J. Ignacio; Irigoien, Xabier; Úbeda, Bárbara; Hernández-León, Santiago; Palma, Álvaro T.; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L.; Duarte, Carlos M.

2014-01-01

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean. PMID:24982135

Human mobility in large cities as a proxy for crime.

PubMed

Caminha, Carlos; Furtado, Vasco; Pequeno, Tarcisio H C; Ponte, Caio; Melo, Hygor P M; Oliveira, Erneson A; Andrade, José S

2017-01-01

We investigate at the subscale of the neighborhoods of a highly populated city the incidence of property crimes in terms of both the resident and the floating population. Our results show that a relevant allometric relation could only be observed between property crimes and floating population. More precisely, the evidence of a superlinear behavior indicates that a disproportional number of property crimes occurs in regions where an increased flow of people takes place in the city. For comparison, we also found that the number of crimes of peace disturbance only correlates well, and in a superlinear fashion too, with the resident population. Our study raises the interesting possibility that the superlinearity observed in previous studies [Bettencourt et al., Proc. Natl. Acad. Sci. USA 104, 7301 (2007) and Melo et al., Sci. Rep. 4, 6239 (2014)] for homicides versus population at the city scale could have its origin in the fact that the floating population, and not the resident one, should be taken as the relevant variable determining the intrinsic microdynamical behavior of the system.

Human mobility in large cities as a proxy for crime

PubMed Central

Caminha, Carlos; Furtado, Vasco; Pequeno, Tarcisio H. C.; Ponte, Caio; Melo, Hygor P. M.; Oliveira, Erneson A.; Andrade, José S.

2017-01-01

We investigate at the subscale of the neighborhoods of a highly populated city the incidence of property crimes in terms of both the resident and the floating population. Our results show that a relevant allometric relation could only be observed between property crimes and floating population. More precisely, the evidence of a superlinear behavior indicates that a disproportional number of property crimes occurs in regions where an increased flow of people takes place in the city. For comparison, we also found that the number of crimes of peace disturbance only correlates well, and in a superlinear fashion too, with the resident population. Our study raises the interesting possibility that the superlinearity observed in previous studies [Bettencourt et al., Proc. Natl. Acad. Sci. USA 104, 7301 (2007) and Melo et al., Sci. Rep. 4, 6239 (2014)] for homicides versus population at the city scale could have its origin in the fact that the floating population, and not the resident one, should be taken as the relevant variable determining the intrinsic microdynamical behavior of the system. PMID:28158268

Plastic debris in the open ocean.

PubMed

Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J Ignacio; Irigoien, Xabier; Ubeda, Bárbara; Hernández-León, Santiago; Palma, Alvaro T; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L; Duarte, Carlos M

2014-07-15

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

Solving Navier-Stokes equations on a massively parallel processor; The 1 GFLOP performance

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

Saati, A.; Biringen, S.; Farhat, C.

This paper reports on experience in solving large-scale fluid dynamics problems on the Connection Machine model CM-2. The authors have implemented a parallel version of the MacCormack scheme for the solution of the Navier-Stokes equations. By using triad floating point operations and reducing the number of interprocessor communications, they have achieved a sustained performance rate of 1.42 GFLOPS.

Livelihood analysis of floating net cages fish farmers at Sendang Village Sub-district of Gajah Mungkur Reservoir of Wonogiri Regency

NASA Astrophysics Data System (ADS)

Nissa, Z. N. A.; Suadi; Sukardi

2018-03-01

Floating net cages farming (KJA) is one of the main livelihood resources in Sendang Village, Gajah Mungkur Reservoir. The purposes of this study were to determine the livelihood asset of fish farmers, the problems of livelihood asset management and the utilization strategy to support aquaculture businesses also farmers livelihood. The study showed that the natural capital, provides easiest way to farmer in fish cultivation. The fish farmers also have good technical capabilities in fish cultivation and the product has high demand and value which is essential for farmers livelihood. The main problems faced by small-scale farmers and all large-scale farmers were transition period, and the rise of cost price which sometime cause the failure in the business. The strategies to deal the problems include technological adjustment, managing the pattern of stocking of tilapia seeds and income source diversification. There were differences in dealing the rise of cost. The small-scale farmers borrow from the bank, while medium-scale farmers use their savings. Another difference of livelihood strategy was the management of financial capital. However, various strategies were still required to increase the livelihood of fish farmers and could address the vulnerabilities in the cultivation of KJA as a common pool resources.

[Post-stroke shoulder-hand syndrome treated with floating-needle therapy combined with rehabilitation training: a randomized controlled trial].

PubMed

Zhou, Zhao-Hui; Zhuang, Li-Xing; Chen, Zhen-Hu; Lang, Jian-Ying; Li, Yan-Hui; Jiang, Gang-Hui; Xu, Zhan-Qiong; Liao, Mu-Xi

2014-07-01

To compare the clinical efficacy in the treatment of post-stroke shoulder-hand syndrome between floating-needle therapy and conventional acupuncture on the basis of rehabilitation training. One hundred cases of post-stroke shoulder-hand syndrome were randomized into a floating-needle group and an acupuncture group, 50 cases in each one. The passive and positive rehabilitation training was adopted in the two groups. Additionally, in the floating-needle group, the floating-needle therapy was used. The needle was inserted at the site 5 to 10 cm away from myofasical trigger point (MTrP), manipulated and scattered subcutaneously, for 2 min continuously. In the acupuncture group, the conventional acupuncture was applied at Jianqian (EX-UE), Jianyu (LI 15), Jianliao (TE 14), etc. The treatment was given once every two days, 3 times a week, and 14 days of treatment were required. The shoulder hand syndrome scale (SHSS), the short form McGill pain scale (SF-MPQ) and the modified Fugl-Meyer motor function scale (FMA) were used to evaluate the damage severity, pain and motor function of the upper limbs before and after treatment in the two groups. The clinical efficacy was compared between the two groups. SHSS score, SF-MPQ score and FMA score were improved significantly after treatment in the two groups (all P < 0.01), and the improvements in the floating-needle group were superior to those in the acupuncture group (all P < 0.05). The total effective rate was 94.0% (47/50) in the floating-needle group, which was better than 90.0% (45/50) in the acupuncture group (P < 0.05). The floating-needle therapy combined with rehabilitation training achieves a satisfactory efficacy on post-stroke shoulder-hand syndrome, which is better than the combined therapy of conventional acupuncture and rehabilitation training.

Effects of Fatigue on Driving Safety: A Comparison of Brake Reaction Times in Night Float and Postcall Physicians in Training.

PubMed

Talusan, Paul G; Long, Theodore; Halim, Andrea; Guliani, Laura; Carroll, Nicole; Reach, John

2014-12-01

Concerns about duty hour and resident safety have fostered discussion about postshift fatigue and driving impairment. We assessed how converting to a night float schedule for overnight coverage affected driving safety for trainees. Brake reaction times were measured for internal medicine and orthopaedic surgery resident volunteers after a traditional 28-hour call shift and after a night float shift. We conducted matched paired t tests of preshift and postshift reaction time means. Participants also completed the Epworth Sleepiness Scale pre- and postshift. From June to July 2013, we enrolled 58 interns and residents (28 orthopaedic surgery, 30 internal medicine). We included 24 (41%) trainees on night float rotations and 34 (59%) trainees on traditional 28-hour call shifts. For all residents on night float rotations, there was no significant difference pre- and postshift. An increase in reaction times was noted among trainees on 28-hour call rotations. This included no effect on reaction times for internal medicine trainees pre- and postshift, and an increase in reaction times for orthopaedic trainees. For both night float and traditional call groups, there were significant increases in the Epworth Sleepiness Scale. Trainees on traditional 28-hour call rotations had significantly worse postshift brake reaction times, whereas trainees on night float rotations had no difference. Orthopaedic trainees had significant differences in brake reaction times after a traditional call shift.

Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

USGS Publications Warehouse

Sasser, C.E.; Gosselink, J.G.; Swenson, E.M.; Swarzenski, C.M.; Leibowitz, N.C.

1996-01-01

In the 1940s extensive floating marshes (locally called 'flotant') were reported and mapped in coastal wetlands of the Mississippi River Delta Plain. These floating marshes included large areas of Panicum hemitomon-dominated freshwater marshes, and Spartina patens/Scirpus olneyi brackish marshes. Today these marshes appear to be quite different in extent and type. We describe five floating habitats and one non-floating, quaking habitat based on differences in buoyancy dynamics (timing and degree of floating), substrate characteristics, and dominant vegetation. All floating marshes have low bulk density, organic substrates. Nearly all are fresh marshes. Panicum hemitomon floating marshes presently occur within the general regions that were reported in the 1940's by O'Neil, but are reduced in extent. Some of the former Panicum hemitomon marshes have been replaced by seasonally or variably floating marshes dominated, or co-dominated by Sagittaria lancifolia or Eleocharis baldwinii. ?? 1996 Kluwer Academic Publishers.

Future float zone development in industry

NASA Technical Reports Server (NTRS)

Sandfort, R. M.

1980-01-01

The present industrial requirements for float zone silicon are summarized. Developments desired by the industry in the future are reported. The five most significant problems faced today by the float zone crystal growth method in industry are discussed. They are economic, large diameter, resistivity uniformity, control of carbon, and swirl defects.

Floating Offshore Wind in Oregon: Potential for Jobs and Economic Impacts from Two Future Scenarios

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

Jimenez, Tony; Keyser, David; Tegen, Suzanne

Construction of the first offshore wind power plant in the United States began in 2015, off the coast of Rhode Island, using fixed platform structures that are appropriate for shallow seafloors, like those located off of the East Coast and mid-Atlantic. However, floating platforms, which have yet to be deployed commercially, will likely need to anchor to the deeper seafloor if deployed off of the West Coast. To analyze the employment and economic potential for floating offshore wind along the West Coast, the Bureau of Ocean Energy Management (BOEM) commissioned the National Renewable Energy Laboratory (NREL) to analyze two hypothetical,more » large-scale deployment scenarios for Oregon: 5,500 megawatts (MW) of offshore wind deployment in Oregon by 2050 (Scenario A), and 2,900 MW of offshore wind by 2050 (Scenario B). These levels of deployment could power approximately 1,600,000 homes (Scenario A) or 870,000 homes (Scenario B). Offshore wind would contribute to economic development in Oregon in the near future, and more substantially in the long term, especially if equipment and labor are sourced from within the state. According to the analysis, over the 2020-2050 period, Oregon floating offshore wind facilities could support 65,000-97,000 job-years and add $6.8 billion-$9.9 billion to the state GDP (Scenario A).« less

Fast and efficient compression of floating-point data.

PubMed

Lindstrom, Peter; Isenburg, Martin

2006-01-01

Large scale scientific simulation codes typically run on a cluster of CPUs that write/read time steps to/from a single file system. As data sets are constantly growing in size, this increasingly leads to I/O bottlenecks. When the rate at which data is produced exceeds the available I/O bandwidth, the simulation stalls and the CPUs are idle. Data compression can alleviate this problem by using some CPU cycles to reduce the amount of data needed to be transfered. Most compression schemes, however, are designed to operate offline and seek to maximize compression, not throughput. Furthermore, they often require quantizing floating-point values onto a uniform integer grid, which disqualifies their use in applications where exact values must be retained. We propose a simple scheme for lossless, online compression of floating-point data that transparently integrates into the I/O of many applications. A plug-in scheme for data-dependent prediction makes our scheme applicable to a wide variety of data used in visualization, such as unstructured meshes, point sets, images, and voxel grids. We achieve state-of-the-art compression rates and speeds, the latter in part due to an improved entropy coder. We demonstrate that this significantly accelerates I/O throughput in real simulation runs. Unlike previous schemes, our method also adapts well to variable-precision floating-point and integer data.

Wave Energy Prize - 1/50th Testing - Float Inc

DOE Data Explorer

Wesley Scharmen

2016-01-15

This submission of data includes all the 1/50th scale testing data completed on the Wave Energy Prize for Float Inc. During the testing of its 1/50th-scale device, Float Inc. Berger ABAM was deemed ineligible due to the fact that they brought a device with them to test and did not ship the device by the deadline stipulated in the Wave Energy Prize Rules. Because of this, analysis, results, and judging were not completed for this team/device. This submission included files such as: 1/50th test data (raw & processed) 1/50th test data video and pictures 1/50th Test plans and testing documents

Effects of Fatigue on Driving Safety: A Comparison of Brake Reaction Times in Night Float and Postcall Physicians in Training

PubMed Central

Talusan, Paul G.; Long, Theodore; Halim, Andrea; Guliani, Laura; Carroll, Nicole; Reach, John

2014-01-01

Background Concerns about duty hour and resident safety have fostered discussion about postshift fatigue and driving impairment. Objective We assessed how converting to a night float schedule for overnight coverage affected driving safety for trainees. Methods Brake reaction times were measured for internal medicine and orthopaedic surgery resident volunteers after a traditional 28-hour call shift and after a night float shift. We conducted matched paired t tests of preshift and postshift reaction time means. Participants also completed the Epworth Sleepiness Scale pre- and postshift. Results From June to July 2013, we enrolled 58 interns and residents (28 orthopaedic surgery, 30 internal medicine). We included 24 (41%) trainees on night float rotations and 34 (59%) trainees on traditional 28-hour call shifts. For all residents on night float rotations, there was no significant difference pre- and postshift. An increase in reaction times was noted among trainees on 28-hour call rotations. This included no effect on reaction times for internal medicine trainees pre- and postshift, and an increase in reaction times for orthopaedic trainees. For both night float and traditional call groups, there were significant increases in the Epworth Sleepiness Scale. Conclusions Trainees on traditional 28-hour call rotations had significantly worse postshift brake reaction times, whereas trainees on night float rotations had no difference. Orthopaedic trainees had significant differences in brake reaction times after a traditional call shift. PMID:26140113

Floating-point scaling technique for sources separation automatic gain control

NASA Astrophysics Data System (ADS)

Fermas, A.; Belouchrani, A.; Ait-Mohamed, O.

2012-07-01

Based on the floating-point representation and taking advantage of scaling factor indetermination in blind source separation (BSS) processing, we propose a scaling technique applied to the separation matrix, to avoid the saturation or the weakness in the recovered source signals. This technique performs an automatic gain control in an on-line BSS environment. We demonstrate the effectiveness of this technique by using the implementation of a division-free BSS algorithm with two inputs, two outputs. The proposed technique is computationally cheaper and efficient for a hardware implementation compared to the Euclidean normalisation.

Large-scale protein/antibody patterning with limiting unspecific adsorption

NASA Astrophysics Data System (ADS)

Fedorenko, Viktoriia; Bechelany, Mikhael; Janot, Jean-Marc; Smyntyna, Valentyn; Balme, Sebastien

2017-10-01

A simple synthetic route based on nanosphere lithography has been developed in order to design a large-scale nanoarray for specific control of protein anchoring. This technique based on two-dimensional (2D) colloidal crystals composed of polystyrene spheres allows the easy and inexpensive fabrication of large arrays (up to several centimeters) by reducing the cost. A silicon wafer coated with a thin adhesion layer of chromium (15 nm) and a layer of gold (50 nm) is used as a substrate. PS spheres are deposited on the gold surface using the floating-transferring technique. The PS spheres were then functionalized with PEG-biotin and the defects by self-assembly monolayer (SAM) PEG to prevent unspecific adsorption. Using epifluorescence microscopy, we show that after immersion of sample on target protein (avidin and anti-avidin) solution, the latter are specifically located on polystyrene spheres. Thus, these results are meaningful for exploration of devices based on a large-scale nanoarray of PS spheres and can be used for detection of target proteins or simply to pattern a surface with specific proteins.

Magnetically driven floating foams for the removal of oil contaminants from water.

PubMed

Calcagnile, Paola; Fragouli, Despina; Bayer, Ilker S; Anyfantis, George C; Martiradonna, Luigi; Cozzoli, P Davide; Cingolani, Roberto; Athanassiou, Athanassia

2012-06-26

In this study, we present a novel composite material based on commercially available polyurethane foams functionalized with colloidal superparamagnetic iron oxide nanoparticles and submicrometer polytetrafluoroethylene particles, which can efficiently separate oil from water. Untreated foam surfaces are inherently hydrophobic and oleophobic, but they can be rendered water-repellent and oil-absorbing by a solvent-free, electrostatic polytetrafluoroethylene particle deposition technique. It was found that combined functionalization of the polytetrafluoroethylene-treated foam surfaces with colloidal iron oxide nanoparticles significantly increases the speed of oil absorption. Detailed microscopic and wettability studies reveal that the combined effects of the surface morphology and of the chemistry of the functionalized foams greatly affect the oil-absorption dynamics. In particular, nanoparticle capping molecules are found to play a major role in this mechanism. In addition to the water-repellent and oil-absorbing capabilities, the functionalized foams exhibit also magnetic responsivity. Finally, due to their light weight, they float easily on water. Hence, by simply moving them around oil-polluted waters using a magnet, they can absorb the floating oil from the polluted regions, thereby purifying the water underneath. This low-cost process can easily be scaled up to clean large-area oil spills in water.

Mesoscale variability of water masses in the Arabian Sea as revealed by ARGO floats

NASA Astrophysics Data System (ADS)

Carton, X.; L'Hegaret, P.; Baraille, R.

2012-03-01

By analysing ARGO float data over the last four years, a few aspects of the mesoscale variability of water masses in the Arabian Sea are described. The Red Sea Outflow Water (RSOW) is concentrated in the Southwestern Gulf of Aden, in particular when a cyclonic gyre predominates in this region. Salinities of 36.5 and temperatures of 16 °C are found in this area at depths between 600 and 1000 m. RSOW is more dilute in the eastern part of the Gulf, where intense and relatively barotropic gyres mix it with Indian ocean Central Water. RSOW is also detected along the northeastern coast of Socotra, and fragments of RSOW are found between one and three degrees of latitude north of this island. In the whole Gulf of Aden, the correlation between the deep motions of the floats and the sea-level anomaly measured by altimetry is strong, at regional scale. The finer scale details of the float trajectories are not sampled by altimetry and are often related to the anomalous water masses that the floats encounter. The Persian Gulf Water (PGW) is found in the float profiles near Ras ash Sharbatat (near 57° E, 18° N), again with 36.5 in salinity and about 18-19 °C in temperature. These observations were achieved in winter when the southwestward monsoon currents can advect PGW along the South Arabian coast. Fragments of PGW were also observed in the Arabian Sea between 18 and 20° N and 63 and 65° E in summer, showing that this water mass can escape the Gulf of Oman southeastward, during that season. Kinetic energy distributions of floats with respect to distance or angle share common features between the two regions (Gulf of Aden and Arabian Sea), in particular peaks at 30, 50 and 150 km scales and along the axis of monsoon currents. Hydrological measurements by floats are also influenced by the seasonal variations of PGW and RSOW in these regions.

Thermal-capillary analysis of small-scale floating zones Steady-state calculations

NASA Technical Reports Server (NTRS)

Duranceau, J. L.; Brown, R. A.

1986-01-01

Galerkin finite element analysis of a thermal-capillary model of the floating zone crystal growth process is used to predict the dependence of molten zone shape on operating conditions for the growth of small silicon boules. The model accounts for conduction-dominated heat transport in the melt, feed rod and growing crystal and for radiation between these phases, the ambient and a heater. Surface tension acting on the shape of the melt/gas meniscus counteracts gravity to set the shape of the molten zone. The maximum diameter of the growing crystal is set by the dewetting of the melt from the feed rod when the crystal radius is large. Calculations with small Bond number show the increased zone lengths possible for growth in a microgravity environment. The sensitivity of the method to the shape and intensity of the applied heating distribution is demonstrated. The calculations are compared with experimental observations.

Description of signature scales in a floating wind turbine model wake subjected to varying turbulence intensity

NASA Astrophysics Data System (ADS)

Kadum, Hawwa; Rockel, Stanislav; Holling, Michael; Peinke, Joachim; Cal, Raul Bayon

2017-11-01

The wake behind a floating model horizontal axis wind turbine during pitch motion is investigated and compared to a fixed wind turbine wake. An experiment is conducted in an acoustic wind tunnel where hot-wire data are acquired at five downstream locations. At each downstream location, a rake of 16 hot-wires was used with placement of the probes increasing radially in the vertical, horizontal, and diagonally at 45 deg. In addition, the effect of turbulence intensity on the floating wake is examined by subjecting the wind turbine to different inflow conditions controlled through three settings in the wind tunnel grid, a passive and two active protocols, thus varying in intensity. The wakes are inspected by statistics of the point measurements, where the various length/time scales are considered. The wake characteristics for a floating wind turbine are compared to a fixed turbine, and uncovering its features; relevant as the demand for exploiting deep waters in wind energy is increasing.

Experimental Study on New Multi-Column Tension-Leg-Type Floating Wind Turbine

NASA Astrophysics Data System (ADS)

Zhao, Yong-sheng; She, Xiao-he; He, Yan-ping; Yang, Jian-min; Peng, Tao; Kou, Yu-feng

2018-04-01

Deep-water regions often have winds favorable for offshore wind turbines, and floating turbines currently show the greatest potential to exploit such winds. This work established proper scaling laws for model tests, which were then implemented in the construction of a model wind turbine with optimally designed blades. The aerodynamic, hydrodynamic, and elastic characteristics of the proposed new multi-column tension-leg-type floating wind turbine (WindStar TLP system) were explored in the wave tank testing of a 1:50 scale model at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University. Tests were conducted under conditions of still water, white noise waves, irregular waves, and combined wind, wave, and current loads. The results established the natural periods of the motion, damping, motion response amplitude operators, and tendon tensions of the WindStar TLP system under different environmental conditions, and thus could serve as a reference for further research. Key words: floating wind turbine, model test, WindStar TLP, dynamic response

Nonvolatile programmable neural network synaptic array

NASA Technical Reports Server (NTRS)

Tawel, Raoul (Inventor)

1994-01-01

A floating-gate metal oxide semiconductor (MOS) transistor is implemented for use as a nonvolatile analog storage element of a synaptic cell used to implement an array of processing synaptic cells. These cells are based on a four-quadrant analog multiplier requiring both X and Y differential inputs, where one Y input is UV programmable. These nonvolatile synaptic cells are disclosed fully connected in a 32 x 32 synaptic cell array using standard very large scale integration (VLSI) complementary MOS (CMOS) technology.

Collective Behavior of Camphor Floats Migrating on the Water Surface

NASA Astrophysics Data System (ADS)

Nishimori, Hiraku; Suematsu, Nobuhiko J.; Nakata, Satoshi

2017-10-01

As simple and easily controllable objects among various self-propelled particles, camphor floats on the water surface have been widely recognized. In this paper, we introduce characteristic behaviors and discuss the background mechanism of camphor floats on water, both in isolated and non-isolated conditions. In particular, we focus on: (i) the transition of dynamical characters through bifurcations exhibited by systems with small number of camphor floats and (ii) the emergence of a rich variety of complex dynamics observed in systems with large number camphor floats, and attempt to elucidate these phenomena through mathematical modeling as well as experimental analysis. Finally, we discuss the connection of the dynamics of camphor floats to that of a wider class of complex and sophisticated dynamics exhibited by various types of self-propelled particles.

77 FR 47876 - Intent To Prepare Environmental Impact Statements: Potential Commercial Wind Lease Issuance and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-10

... Statoil NA's proposed project, Hywind Maine, would consist of four 3-megawatt (MW) floating wind turbine... request by Statoil NA, is to construct a full-scale, deepwater floating wind turbine facility that... Prepare Environmental Impact Statements: Potential Commercial Wind Lease Issuance and Decision Regarding...

A method for data handling numerical results in parallel OpenFOAM simulations

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

Anton, Alin; Muntean, Sebastian

Parallel computational fluid dynamics simulations produce vast amount of numerical result data. This paper introduces a method for reducing the size of the data by replaying the interprocessor traffic. The results are recovered only in certain regions of interest configured by the user. A known test case is used for several mesh partitioning scenarios using the OpenFOAM toolkit{sup ®}[1]. The space savings obtained with classic algorithms remain constant for more than 60 Gb of floating point data. Our method is most efficient on large simulation meshes and is much better suited for compressing large scale simulation results than the regular algorithms.

Nutrient removal by up-scaling a hybrid floating treatment bed (HFTB) using plant and periphyton: From laboratory tank to polluted river.

PubMed

Liu, Junzhuo; Wang, Fengwu; Liu, Wei; Tang, Cilai; Wu, Chenxi; Wu, Yonghong

2016-05-01

Planted floating treatment bed (FTB) is an innovative technique of removing nutrients from polluted water but limited in deep water and cold seasons. Periphyton was integrated into FTB for a hybrid floating treatment bed (HFTB) to improve its nutrient removal capacity. To assess its potential for treating nutrient-polluted rivers, HFTB was up-scaled from 5L laboratory tanks to 350L outdoor tanks and then to a commercial-scale 900m section of polluted river. Plants and periphyton interacted in HFTB with periphyton limiting plant root growth and plants having shading effects on periphyton. Non-overlapping distribution of plants and periphyton can minimize the negative interactions in HFTB. HFTB successfully kept TN and TP of the river at less than 2.0 and 0.02mgL(-1), respectively. This study indicates that HFTB can be easily up-scaled for nutrients removal from polluted rivers in different seasons providing a long-term, environmentally-friendly method to remediate polluted ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Yield comparisons from floating blade and fixed arbor gang ripsaws when processing boards before and after crook removal

Treesearch

Charles J. Gatchell; Charles J. Gatchell

1991-01-01

Gang-ripping technology that uses a movable (floating) outer blade to eliminate unusable edgings is described, including new tenn1nology for identifying preferred and minimally acceptable strip widths. Because of the large amount of salvage required to achieve total yields, floating blade gang ripping is not recommended for boards with crook. With crook removed by...

The Scale Effect in Towing Tests with Airplane-float Systems

NASA Technical Reports Server (NTRS)

Schmidt, Rudolph

1937-01-01

The present report includes a description of the making of three-component measurements on a full-size float mounted on an actual airplane and the comparison of the results with those from two models of the same form but of different size which had been tested in the towing tank. The purpose of the comparison is to determine the effect of the Reynolds Number on the results of model tank tests. Following a brief discussion of previous tests intended to elucidate the problem of scale effect on float systems and a description of the testing equipment, the choice of the reference quantities to be used in the comparison is discussed. The selection of load, speed, and trim as a basis of comparison seems best suited to the practical operation of making this comparison. The quantities affected by scale are then: resistance, trimming moment, and their derivatives; planing number (resistance/weight on water); and position of center of pressure.

The VolturnUS 1:8 Floating Wind Turbine: Design, Construction, Deployment, Testing, Retrieval, and Inspection of the First Grid-Connected Offshore Wind Turbine in US

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

Dagher, Habib; Viselli, Anthony; Goupee, Andrew

Volume II of the Final Report for the DeepCwind Consortium National Research Program funded by US Department of Energy Award Number: DE-EE0003278.001 summarizes the design, construction, deployment, testing, numerical model validation, retrieval, and post-deployment inspection of the VolturnUS 1:8-scale floating wind turbine prototype deployed off Castine, Maine on June 2nd, 2013. The 1:8 scale VolturnUS design served as a de-risking exercise for a commercial multi-MW VolturnUS design. The American Bureau of Shipping Guide for Building and Classing Floating Offshore Wind Turbine Installations was used to design the prototype. The same analysis methods, design methods, construction techniques, deployment methods, mooring, andmore » anchoring planned for full-scale were used. A commercial 20kW grid-connected turbine was used and was the first offshore wind turbine in the US.« less

Sleep, activity and fatigue reported by postgraduate year 1 residents: a prospective cohort study comparing the effects of night-float versus traditional overnight on-call.

PubMed

Low, Jia Ming; Tan, Mae Yue; See, Kay Choong; Aw, Marion M

2018-03-19

As traditional overnight on-call was shown to contribute to fatigue, Singapore moved to implement a shift system in 2014. We aimed to compare activity levels, sleep (using a wrist actigraph), fatigue and professional quality-of-life between residents working on night-float and those working on traditional overnight on-call. All postgraduate year 1 (PGY1) residents at our institution were invited to participate. Participants were required to wear a wrist actigraph for four months, and complete two validated surveys (Epworth Sleepiness Scale [ESS] and Professional Quality of Life Scale [ProQOL]) once each at the start and at the end of study. 49 residents were recruited. Residents on night-float and on-call showed comparable median (range) number of steps (10,061 [1,195-15,923] vs. 10,649 [308-21,910]; p = 0.429), amount of sleep logged (361 [149-630] minutes vs. 380 [175-484] minutes; p = 0.369) and time taken to fall asleep (6 [0-14] minutes vs. 6 [range 0-45] minutes; p = 0.726) respectively. Residents on night-float had less efficient sleep, with 90.5% participants having over 85% sleep efficiency compared to 100% of residents on on-call (p = 0.127). More residents on night-float reported ESS > 10 (73.8% vs. 38.5%) and higher burnout scores on ProQOL (41.4% vs. 21.4%) at the start of the study. However, this was similar to the end of the study and was not statistically significant. The physical activity and amount of sleep of residents on night-float and on-call rota were not significantly different. Residents on night-float reported comparatively higher fatigue and burnout.

See-Through Imaging of Laser-Scanned 3d Cultural Heritage Objects Based on Stochastic Rendering of Large-Scale Point Clouds

NASA Astrophysics Data System (ADS)

Tanaka, S.; Hasegawa, K.; Okamoto, N.; Umegaki, R.; Wang, S.; Uemura, M.; Okamoto, A.; Koyamada, K.

2016-06-01

We propose a method for the precise 3D see-through imaging, or transparent visualization, of the large-scale and complex point clouds acquired via the laser scanning of 3D cultural heritage objects. Our method is based on a stochastic algorithm and directly uses the 3D points, which are acquired using a laser scanner, as the rendering primitives. This method achieves the correct depth feel without requiring depth sorting of the rendering primitives along the line of sight. Eliminating this need allows us to avoid long computation times when creating natural and precise 3D see-through views of laser-scanned cultural heritage objects. The opacity of each laser-scanned object is also flexibly controllable. For a laser-scanned point cloud consisting of more than 107 or 108 3D points, the pre-processing requires only a few minutes, and the rendering can be executed at interactive frame rates. Our method enables the creation of cumulative 3D see-through images of time-series laser-scanned data. It also offers the possibility of fused visualization for observing a laser-scanned object behind a transparent high-quality photographic image placed in the 3D scene. We demonstrate the effectiveness of our method by applying it to festival floats of high cultural value. These festival floats have complex outer and inner 3D structures and are suitable for see-through imaging.

Method of manufacturing large dish reflectors for a solar concentrator apparatus

DOEpatents

Angel, Roger P [Tucson, AZ; Olbert, Blain H [Tucson, AZ

2011-12-27

A method of manufacturing monolithic glass reflectors for concentrating sunlight in a solar energy system is disclosed. The method of manufacturing allows large monolithic glass reflectors to be made from float glass in order to realize significant cost savings on the total system cost for a solar energy system. The method of manufacture includes steps of heating a sheet of float glass positioned over a concave mold until the sheet of glass sags and stretches to conform to the shape of the mold. The edges of the dish-shaped glass are rolled for structural stiffening around the periphery. The dish-shaped glass is then silvered to create a dish-shaped mirror that reflects solar radiation to a focus. The surface of the mold that contacts the float glass preferably has a grooved surface profile comprising a plurality of cusps and concave valleys. This grooved profile minimizes the contact area and marring of the specular glass surface, reduces parasitic heat transfer into the mold and increases mold lifetime. The disclosed method of manufacture is capable of high production rates sufficiently fast to accommodate the output of a conventional float glass production line so that monolithic glass reflectors can be produced as quickly as a float glass production can make sheets of float glass to be used in the process.

Feasibility of Floating Platform Systems for Wind Turbines: Preprint

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

Musial, W.; Butterfield, S.; Boone, A.

This paper provides a general technical description of several types of floating platforms for wind turbines. Platform topologies are classified into multiple- or single-turbine floaters and by mooring method. Platforms using catenary mooring systems are contrasted to vertical mooring systems and the advantages and disadvantages are discussed. Specific anchor types are described in detail. A rough cost comparison is performed for two different platform architectures using a generic 5-MW wind turbine. One platform is a Dutch study of a tri-floater platform using a catenary mooring system, and the other is a mono-column tension-leg platform developed at the National Renewable Energymore » Laboratory. Cost estimates showed that single unit production cost is $7.1 M for the Dutch tri-floater, and $6.5 M for the NREL TLP concept. However, value engineering, multiple unit series production, and platform/turbine system optimization can lower the unit platform costs to $4.26 M and $2.88 M, respectively, with significant potential to reduce cost further with system optimization. These foundation costs are within the range necessary to bring the cost of energy down to the DOE target range of $0.05/kWh for large-scale deployment of offshore floating wind turbines.« less

Quantification and Analysis of Icebergs in a Tidewater Glacier Fjord Using an Object-Based Approach.

PubMed

McNabb, Robert W; Womble, Jamie N; Prakash, Anupma; Gens, Rudiger; Haselwimmer, Christian E

2016-01-01

Tidewater glaciers are glaciers that terminate in, and calve icebergs into, the ocean. In addition to the influence that tidewater glaciers have on physical and chemical oceanography, floating icebergs serve as habitat for marine animals such as harbor seals (Phoca vitulina richardii). The availability and spatial distribution of glacier ice in the fjords is likely a key environmental variable that influences the abundance and distribution of selected marine mammals; however, the amount of ice and the fine-scale characteristics of ice in fjords have not been systematically quantified. Given the predicted changes in glacier habitat, there is a need for the development of methods that could be broadly applied to quantify changes in available ice habitat in tidewater glacier fjords. We present a case study to describe a novel method that uses object-based image analysis (OBIA) to classify floating glacier ice in a tidewater glacier fjord from high-resolution aerial digital imagery. Our objectives were to (i) develop workflows and rule sets to classify high spatial resolution airborne imagery of floating glacier ice; (ii) quantify the amount and fine-scale characteristics of floating glacier ice; (iii) and develop processes for automating the object-based analysis of floating glacier ice for large number of images from a representative survey day during June 2007 in Johns Hopkins Inlet (JHI), a tidewater glacier fjord in Glacier Bay National Park, southeastern Alaska. On 18 June 2007, JHI was comprised of brash ice ([Formula: see text] = 45.2%, SD = 41.5%), water ([Formula: see text] = 52.7%, SD = 42.3%), and icebergs ([Formula: see text] = 2.1%, SD = 1.4%). Average iceberg size per scene was 5.7 m2 (SD = 2.6 m2). We estimate the total area (± uncertainty) of iceberg habitat in the fjord to be 455,400 ± 123,000 m2. The method works well for classifying icebergs across scenes (classification accuracy of 75.6%); the largest classification errors occur in areas with densely-packed ice, low contrast between neighboring ice cover, or dark or sediment-covered ice, where icebergs may be misclassified as brash ice about 20% of the time. OBIA is a powerful image classification tool, and the method we present could be adapted and applied to other ice habitats, such as sea ice, to assess changes in ice characteristics and availability.

Quantification and Analysis of Icebergs in a Tidewater Glacier Fjord Using an Object-Based Approach

PubMed Central

McNabb, Robert W.; Womble, Jamie N.; Prakash, Anupma; Gens, Rudiger; Haselwimmer, Christian E.

2016-01-01

Tidewater glaciers are glaciers that terminate in, and calve icebergs into, the ocean. In addition to the influence that tidewater glaciers have on physical and chemical oceanography, floating icebergs serve as habitat for marine animals such as harbor seals (Phoca vitulina richardii). The availability and spatial distribution of glacier ice in the fjords is likely a key environmental variable that influences the abundance and distribution of selected marine mammals; however, the amount of ice and the fine-scale characteristics of ice in fjords have not been systematically quantified. Given the predicted changes in glacier habitat, there is a need for the development of methods that could be broadly applied to quantify changes in available ice habitat in tidewater glacier fjords. We present a case study to describe a novel method that uses object-based image analysis (OBIA) to classify floating glacier ice in a tidewater glacier fjord from high-resolution aerial digital imagery. Our objectives were to (i) develop workflows and rule sets to classify high spatial resolution airborne imagery of floating glacier ice; (ii) quantify the amount and fine-scale characteristics of floating glacier ice; (iii) and develop processes for automating the object-based analysis of floating glacier ice for large number of images from a representative survey day during June 2007 in Johns Hopkins Inlet (JHI), a tidewater glacier fjord in Glacier Bay National Park, southeastern Alaska. On 18 June 2007, JHI was comprised of brash ice (x¯ = 45.2%, SD = 41.5%), water (x¯ = 52.7%, SD = 42.3%), and icebergs (x¯ = 2.1%, SD = 1.4%). Average iceberg size per scene was 5.7 m2 (SD = 2.6 m2). We estimate the total area (± uncertainty) of iceberg habitat in the fjord to be 455,400 ± 123,000 m2. The method works well for classifying icebergs across scenes (classification accuracy of 75.6%); the largest classification errors occur in areas with densely-packed ice, low contrast between neighboring ice cover, or dark or sediment-covered ice, where icebergs may be misclassified as brash ice about 20% of the time. OBIA is a powerful image classification tool, and the method we present could be adapted and applied to other ice habitats, such as sea ice, to assess changes in ice characteristics and availability. PMID:27828967

Development of performance specifications for hybrid modeling of floating wind turbines in wave basin tests

DOE PAGES

Hall, Matthew; Goupee, Andrew; Jonkman, Jason

2017-08-24

Hybrid modeling—combining physical testing and numerical simulation in real time$-$opens new opportunities in floating wind turbine research. Wave basin testing is an important validation step for floating support structure design, but the conventional approaches that use physical wind above the basin are limited by scaling problems in the aerodynamics. Applying wind turbine loads with an actuation system that is controlled by a simulation responding to the basin test in real time offers a way to avoid scaling problems and reduce cost barriers for floating wind turbine design validation in realistic coupled wind and wave conditions. This paper demonstrates the developmentmore » of performance specifications for a system that couples a wave basin experiment with a wind turbine simulation. Two different points for the hybrid coupling are considered: the tower-base interface and the aero-rotor interface (the boundary between aerodynamics and the rotor structure). Analyzing simulations of three floating wind turbine designs across seven load cases reveals the motion and force requirements of the coupling system. By simulating errors in the hybrid coupling system, the sensitivity of the floating wind turbine response to coupling quality can be quantified. The sensitivity results can then be used to determine tolerances for motion tracking errors, force actuation errors, bandwidth limitations, and latency in the hybrid coupling system. These tolerances can guide the design of hybrid coupling systems to achieve desired levels of accuracy. An example demonstrates how the developed methods can be used to generate performance specifications for a system at 1:50 scale. Results show that sensitivities vary significantly between support structure designs and that coupling at the aero-rotor interface has less stringent requirements than those for coupling at the tower base. As a result, the methods and results presented here can inform design of future hybrid coupling systems and enhance understanding of how test results are affected by hybrid coupling quality.« less

Development of performance specifications for hybrid modeling of floating wind turbines in wave basin tests

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

Hall, Matthew; Goupee, Andrew; Jonkman, Jason

Hybrid modeling—combining physical testing and numerical simulation in real time$-$opens new opportunities in floating wind turbine research. Wave basin testing is an important validation step for floating support structure design, but the conventional approaches that use physical wind above the basin are limited by scaling problems in the aerodynamics. Applying wind turbine loads with an actuation system that is controlled by a simulation responding to the basin test in real time offers a way to avoid scaling problems and reduce cost barriers for floating wind turbine design validation in realistic coupled wind and wave conditions. This paper demonstrates the developmentmore » of performance specifications for a system that couples a wave basin experiment with a wind turbine simulation. Two different points for the hybrid coupling are considered: the tower-base interface and the aero-rotor interface (the boundary between aerodynamics and the rotor structure). Analyzing simulations of three floating wind turbine designs across seven load cases reveals the motion and force requirements of the coupling system. By simulating errors in the hybrid coupling system, the sensitivity of the floating wind turbine response to coupling quality can be quantified. The sensitivity results can then be used to determine tolerances for motion tracking errors, force actuation errors, bandwidth limitations, and latency in the hybrid coupling system. These tolerances can guide the design of hybrid coupling systems to achieve desired levels of accuracy. An example demonstrates how the developed methods can be used to generate performance specifications for a system at 1:50 scale. Results show that sensitivities vary significantly between support structure designs and that coupling at the aero-rotor interface has less stringent requirements than those for coupling at the tower base. As a result, the methods and results presented here can inform design of future hybrid coupling systems and enhance understanding of how test results are affected by hybrid coupling quality.« less

Observations of Transient ISS Floating Potential Variations During High Voltage Solar Array Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda N.; Pour, Maria Z. A.; Swenson, Charles; Nishikawa, Ken-ichi; Krause, Linda Habash

2016-01-01

The International Space Station (ISS) continues to be a world-class space research laboratory after over 15 years of operations, and it has proven to be a fantastic resource for observing spacecraft floating potential variations related to high voltage solar array operations in Low Earth Orbit (LEO). Measurements of the ionospheric electron density and temperature along the ISS orbit and variations in the ISS floating potential are obtained from the Floating Potential Measurement Unit (FPMU). In particular, rapid variations in ISS floating potential during solar array operations on time scales of tens of milliseconds can be recorded due to the 128 Hz sample rate of the Floating Potential Probe (FPP) pro- viding interesting insight into high voltage solar array interaction with the space plasma environment. Comparing the FPMU data with the ISS operations timeline and solar array data provides a means for correlating some of the more complex and interesting transient floating potential variations with mission operations. These complex variations are not reproduced by current models and require further study to understand the underlying physical processes. In this paper we present some of the floating potential transients observed over the past few years along with the relevant space environment parameters and solar array operations data.

Floating plant dominance as a stable state

PubMed Central

Scheffer, Marten; Szabó, Sándor; Gragnani, Alessandra; van Nes, Egbert H.; Rinaldi, Sergio; Kautsky, Nils; Norberg, Jon; Roijackers, Rudi M. M.; Franken, Rob J. M.

2003-01-01

Invasion by mats of free-floating plants is among the most important threats to the functioning and biodiversity of freshwater ecosystems ranging from temperate ponds and ditches to tropical lakes. Dark, anoxic conditions under thick floating-plant cover leave little opportunity for animal or plant life, and they can have large negative impacts on fisheries and navigation in tropical lakes. Here, we demonstrate that floating-plant dominance can be a self-stabilizing ecosystem state, which may explain its notorious persistence in many situations. Our results, based on experiments, field data, and models, represent evidence for alternative domains of attraction in ecosystems. An implication of our findings is that nutrient enrichment reduces the resilience of freshwater systems against a shift to floating-plant dominance. On the other hand, our results also suggest that a single drastic harvest of floating plants can induce a permanent shift to an alternative state dominated by rooted, submerged growth forms. PMID:12634429

Solution processed molecular floating gate for flexible flash memories

NASA Astrophysics Data System (ADS)

Zhou, Ye; Han, Su-Ting; Yan, Yan; Huang, Long-Biao; Zhou, Li; Huang, Jing; Roy, V. A. L.

2013-10-01

Solution processed fullerene (C60) molecular floating gate layer has been employed in low voltage nonvolatile memory device on flexible substrates. We systematically studied the charge trapping mechanism of the fullerene floating gate for both p-type pentacene and n-type copper hexadecafluorophthalocyanine (F16CuPc) semiconductor in a transistor based flash memory architecture. The devices based on pentacene as semiconductor exhibited both hole and electron trapping ability, whereas devices with F16CuPc trapped electrons alone due to abundant electron density. All the devices exhibited large memory window, long charge retention time, good endurance property and excellent flexibility. The obtained results have great potential for application in large area flexible electronic devices.

Solution processed molecular floating gate for flexible flash memories

PubMed Central

Zhou, Ye; Han, Su-Ting; Yan, Yan; Huang, Long-Biao; Zhou, Li; Huang, Jing; Roy, V. A. L.

2013-01-01

Solution processed fullerene (C60) molecular floating gate layer has been employed in low voltage nonvolatile memory device on flexible substrates. We systematically studied the charge trapping mechanism of the fullerene floating gate for both p-type pentacene and n-type copper hexadecafluorophthalocyanine (F16CuPc) semiconductor in a transistor based flash memory architecture. The devices based on pentacene as semiconductor exhibited both hole and electron trapping ability, whereas devices with F16CuPc trapped electrons alone due to abundant electron density. All the devices exhibited large memory window, long charge retention time, good endurance property and excellent flexibility. The obtained results have great potential for application in large area flexible electronic devices. PMID:24172758

Calibration and validation of a spar-type floating offshore wind turbine model using the FAST dynamic simulation tool

DOE PAGES

Browning, J. R.; Jonkman, J.; Robertson, A.; ...

2014-12-16

In this study, high-quality computer simulations are required when designing floating wind turbines because of the complex dynamic responses that are inherent with a high number of degrees of freedom and variable metocean conditions. In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50 th scalemore » in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states. Wave basin tests with the spar attached to a scale model of the NREL 5-megawatt reference wind turbine were performed at the Maritime Research Institute Netherlands under the DeepCwind project. This project included free-decay tests, tests with steady or turbulent wind and still water (both periodic and irregular waves with no wind), and combined wind/wave tests. The resulting data from the 1/50th model was scaled using Froude scaling to full size and used to calibrate and validate a full-size simulated model in FAST. Results of the model calibration and validation include successes, subtleties, and limitations of both wave basin testing and FAST modeling capabilities.« less

Ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory

NASA Astrophysics Data System (ADS)

Han, Jinhua; Wang, Wei; Ying, Jun; Xie, Wenfa

2014-01-01

An ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory was demonstrated, with discrete distributed gold nanoparticles, tetratetracontane (TTC), pentacene as the floating-gate layer, tunneling layer, and active layer, respectively. The electron traps at the TTC/pentacene interface were significantly suppressed, which resulted in an ambipolar operation in present memory. As both electrons and holes were supplied in the channel and trapped in the floating-gate by programming/erasing operations, respectively, i.e., one type of charge carriers was used to overwrite the other, trapped, one, a large memory window, extending on both sides of the initial threshold voltage, was realized.

The impact on floats or hulls during landing as affected by bottom width

NASA Technical Reports Server (NTRS)

Mewes, E

1936-01-01

For floats and hulls having V bottoms the impact force does not necessarily increase with increasing width. Therefore, the weight of the float landing gear, side walls, and other parts, and of the fuselage construction need not be increased with increasing bottom width, but the weight of the bottom construction itself, on the other hand, does not increase with increase in bottom width and is largely determined by the type of construction.

A case study of middle size floating airports for shallower and deeper waters

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

Yoshida, Koichiro; Suzuki, Hideyuki; Nishigaki, Makoto

1996-12-31

Demands for large and middle size airports are expanding in Japan with continuous increase of air transportation. However these demands will not be satisfied without effective ocean space utilization. Most of the wide and shallower waters suitable for reclamation have already been reclaimed. Furthermore those shallower waters are generally close to the residential area, and noise and environmental problems will be caused if they were used for airports. Deeper waters, which are relatively distant from the shore, are suitable for airport but reclamation of these waters are extremely difficult. This paper presents a structural planning of an open sea typemore » middle size floating airport to promote local economy and also improve transportation infrastructure of isolated islands. The airports of this plan are a semisubmersible type floating structure with a relatively thin deck, a number of slender columns and large size lower hulls. The floating structure is moored by inclined tension legs to restrain the motion. The diameter of the leg becomes much larger compared with the legs of existing tension leg platforms. Parameters related to the configuration of the floating structure and the mooring system are determined by comparing analyses results with the proper design criteria. Several kinds of static and dynamic computer programs are used in the planning. The proposed structural plan and the mooring system are considered as a typical floating airport appropriate for the open sea.« less

True polar wander on Europa from global-scale small-circle depressions.

PubMed

Schenk, Paul; Matsuyama, Isamu; Nimmo, Francis

2008-05-15

The tectonic patterns and stress history of Europa are exceedingly complex and many large-scale features remain unexplained. True polar wander, involving reorientation of Europa's floating outer ice shell about the tidal axis with Jupiter, has been proposed as a possible explanation for some of the features. This mechanism is possible if the icy shell is latitudinally variable in thickness and decoupled from the rocky interior. It would impose high stress levels on the shell, leading to predictable fracture patterns. No satisfactory match to global-scale features has hitherto been found for polar wander stress patterns. Here we describe broad arcuate troughs and depressions on Europa that do not fit other proposed stress mechanisms in their current position. Using imaging from three spacecraft, we have mapped two global-scale organized concentric antipodal sets of arcuate troughs up to hundreds of kilometres long and 300 m to approximately 1.5 km deep. An excellent match to these features is found with stresses caused by an episode of approximately 80 degrees true polar wander. These depressions also appear to be geographically related to other large-scale bright and dark lineaments, suggesting that many of Europa's tectonic patterns may also be related to true polar wander.

Float-zone processing in a weightless environment

NASA Technical Reports Server (NTRS)

Fowle, A. A.; Haggerty, J. S.; Perron, R. R.; Strong, P. F.; Swanson, J. L.

1976-01-01

The results were reported of investigations to: (1) test the validity of analyses which set maximum practical diameters for Si crystals that can be processed by the float zone method in a near weightless environment, (2) determine the convective flow patterns induced in a typical float zone, Si melt under conditions perceived to be advantageous to the crystal growth process using flow visualization techniques applied to a dimensionally scaled model of the Si melt, (3) revise the estimates of the economic impact of space produced Si crystal by the float zone method on the U.S. electronics industry, and (4) devise a rational plan for future work related to crystal growth phenomena wherein low gravity conditions available in a space site can be used to maximum benefit to the U.S. electronics industry.

Analysis of evolution of meddies in the North Atlantic using float experiments and multi - sensor data

NASA Astrophysics Data System (ADS)

Jo, Y.; Yan, X.; Zheng, Q.; Klemas, V. V.; Liu, W.

2002-05-01

We analyzed the interactions of Mediterranean eddies (meddies) in the North Atlantic with large - and meso - scale dynamic processes. The study focuses on the baroclinic instability due to the surface wind forcing, topographical Rossby wave (TRW) and the meddies' signals in multi-sensor data. The Hilbert - Huang's Energy - Frequency - Time spectrum was employed to estimate the dominant frequency. The major power peak of the surface wind forcing and sea surface height anomaly occurs every 33 months and relates to horizontal translation of the southwestward meddies. This frequency is quite close to M\\x81ler and Siedler's (1992) zonal variability with periods of 3 - 4 years. The subsequent power peaks in the vertical displacement of the meddies are at 5 day and 10 day intervals as derived from AMUSE and SEMAPHORE experiments (1993 - 1995). These 5 and 10 day periods may be caused by the intrusion of dense Mediterranean water. The contributions of the rotation speed, thermal expansion, and vertical fluctuation in the meddies' signals were estimated using the data taken by the AMUSE and the SEMAPHORE experiments. Consequently, mean monthly climatological meddies' signals from the multi-sensor analysis and float measurements show that the meddies mean kinetic energy is related to topographic scales.

Wind-Tunnel Tests of the 1/25-Scale Powered Model of the Martin JRM-1 Airplane. IV - Tests with Ground Board and with Modified Wing and Hull - TED No. NACA 232. Part 4; Tests with Ground Board and with Modified Wing and Hull, TED No. NACA 232

NASA Technical Reports Server (NTRS)

Lockwood, Vernard E.; Smith, Bernard J.

1947-01-01

Wind-tunnel tests were made of a 1/25 scale model of the Martin JRM-1 airplane to determine: (1) The longitudinal stability and control characteristics of the JRM-1 model near the water and lateral and directional stability characteristics with power while moving on the surface of the water, the latter being useful for the design of tip floats; (2) The stability and stalling characteristics of the wing with a modified airfoil contour; (3) Stability characteristics of a hull of larger design gross weight; The test results indicated that the elevator was powerful enough to trim the original model in a landing configuration at any lift coefficient within the specified range of centers of gravity. The ground-board tests for evaluating the aerodynamic forces and moments on an airplane in a simulated cross wind indicate a high dihedral effect in the presence of the ground board and, consequently, during low-speed taxying and take-off, large overturning moments would result which would have to be overcome by the tip floats.

Dynamics of a bilayer membrane coupled to a two-dimensional cytoskeleton: Scale transfers of membrane deformations

NASA Astrophysics Data System (ADS)

Okamoto, Ryuichi; Komura, Shigeyuki; Fournier, Jean-Baptiste

2017-07-01

We theoretically investigate the dynamics of a floating lipid bilayer membrane coupled with a two-dimensional cytoskeleton network, taking into account explicitly the intermonolayer friction, the discrete lattice structure of the cytoskeleton, and its prestress. The lattice structure breaks lateral continuous translational symmetry and couples Fourier modes with different wave vectors. It is shown that within a short time interval a long-wavelength deformation excites a collection of modes with wavelengths shorter than the lattice spacing. These modes relax slowly with a common renormalized rate originating from the long-wavelength mode. As a result, and because of the prestress, the slowest relaxation is governed by the intermonolayer friction. Conversely, and most interestingly, forces applied at the scale of the cytoskeleton for a sufficiently long time can cooperatively excite large-scale modes.

Large structures and temporal change in the Azores Front during the SEMAPHORE experiment

NASA Astrophysics Data System (ADS)

Tychensky, A.; Le Traon, P.-Y.; Hernandez, F.; Jourdan, D.

1998-10-01

The Structure des Echanges Mer-Atmosphere, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) mesoscale experiment took place from July to November 1993 in the northern Canary Basin, where the circulation is dominated by the eastward flowing Azores Current (AC). A large data set was acquired from three hydrographic arrays (phases 1, 2, 3), current meter moorings, surface drifters drogued at 150 m, and 2000 m deep RAFOS floats. The analysis confirmed the large-scale observations previously made in this region but also provided new insights into fine-scale dynamics of the AC. The front was observed over the 6-month period. It was narrow (100 km) and mostly surface intensified (velocities reaching 40-50 cm s-1). Whereas at the beginning of the experiment (phase 1) the AC was mainly zonal with weak oscillations, large meridional meanders were observed from phase 2 until the end of the experiment. They seem to be related to the arrival of two Mediterranean eddies (Meddies), which interacted with the AC [Käse and Zenk, 1996; Tychensky and Carton, this issue]. The front had a deep dynamical signature (down to 2000 m), with a 16-18 sverdrup (Sv) volume transport (0-2000 m depth integrated). The southward recirculation branch of the AC near 22°-23°W [Klein and Siedler, 1989] corresponds to meridional transport of 5-6 Sv. Then, 4.5 Sv of these waters are recirculating westward (along 31°-32°N). Some interesting new oceanographic results were obtained by examining the RAFOS float trajectories over the abyssal plain. The circulation is similar to that observed at the surface, with mean velocities of about 1-3 cm s-1 and eddy kinetic energy <4 cm2 s-2. In agreement with the analysis of current meter data this reveals a significant barotropic component in the Azores-Madeira flow field of roughly 3-3.5 cm s-1.

Post-LGM grounding line and calving front translations of the West Antarctic Ice Sheet in the Whales Deep paleo-ice-stream trough, eastern Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

McGlannan, A. J.; Bart, P. J.; Chow, J.

2016-12-01

A large-area (2500 km2) multibeam survey of the Whales Deep paleo-ice-stream trough, eastern Ross Sea, Antarctica was acquired during NBP1502B. This sector of the continental shelf is important as it was covered by grounded and floating ice, which drained the central part of an expanded West Antarctic Ice Sheet (WAIS) during the last glacial cycle. The seafloor geomorphology shows a well-defined cluster of four back stepping grounding zone wedges (GZWs) that were deposited in a partly overlapping fashion on the middle continental shelf during WAIS retreat. These observations permit two end-member possibilities for how the WAIS grounding line and calving front vacated the trough. In the first scenario, each GZW represents successive landward shifts of the grounding line and calving front. In the second scenario, each GZW represents a large-scale retreat and re-advance of grounded and floating ice. To determine which of these two end-member scenarios most accurately describes WAIS retreat from this sector of Ross Sea, we evaluated a grid of kasten and piston cores. The core stations were selected on the basis of backstepping GZWs along the trough axis. Our core data analyses included an integration of visual core descriptions, x-ray images, grain size, water content, total organic carbon, shear strengths, and diatom assemblage data. Core data reveal a single transgressive succession from proximal diamict overlain by sub-ice-shelf and/or open-marine sediments. These data strongly support the first scenario, suggesting that an ice shelf remained continuously intact during the time that the grounding line successively moved from the shelf edge to the middle shelf by small-scale landward translations until the end of the fourth grounding event. Sedimentologic and diatom-assemblage data from the inner shelf show that only the last middle shelf grounding event ended with a long-distance retreat of grounded and then floating ice to south of the modern calving front.

Impact of Preferred Eddy Tracks on Transport and Mixing in the Eastern South Pacific

NASA Astrophysics Data System (ADS)

Belmadani, A.; Donoso, D.; Auger, P. A.; Chaigneau, A.

2017-12-01

Mesoscale eddies, which play a fundamental role in the transport of mass, heat, nutrients, and biota across the oceans, have been suggested to propagate preferently along specific tracks. These preferred pathways, also called eddy trains, are near-zonal due to westward drift of individual vortices, and tend to be polarized (ie alternatively dominated by anticyclonic/cyclonic eddies), coinciding with the recently discovered latent striations (quasi-zonal mesoscale jet-like features). While significant effort has been made to understand the dynamics of striations and their interplay with mesoscale eddies, the impact of repeated eddy tracks on physical (temperature, salinity), biogeochemical (oxygen, carbon, nutrients) and other tracers (e.g. chlorophyll, marine debris) has received little attention. Here we report on the results of numerical modeling experiments that simulate the impact of preferred eddy tracks on the transport and mixing of water particles in the Eastern South Pacific off Chile. A 30-year interannual simulation of the oceanic circulation in this region has been performed over 1984-2013 with the ROMS (Regional Oceanic Modeling System) at an eddy-resolving resolution (10 km). Objective tracking of mesoscale coherent vortices is obtained using automated methods, allowing to compute the contribution of eddies to the ocean circulation. Preferred eddy tracks are further isolated from the more random eddies, by comparing the distances between individual tracks and the striated pattern in long-term mean eddy polarity with a least-squares approach. The remaining non-eddying flow may also be decomposed into time-mean and anomalous circulation, and/or small- and large-scale circulation. Neutrally-buoyant Lagrangian floats are then released uniformly into the various flow components as well as the total flow, and tracked forward in time with the ARIANE software. The dispersion patterns of water particles are used to estimate the respective contributions of organized and random eddies, mean flow, large-scale perturbations etc. to mixing properties and transport pathways. Float release into the full flow inside selected vortices is also used to document the impact of eddy trains on the transformation of water masses inferred from changes in temperature/salinity along float trajectories.

Circulation, eddies, oxygen and nutrient changes in the eastern tropical South Pacific Ocean

NASA Astrophysics Data System (ADS)

Czeschel, R.; Stramma, L.; Weller, R. A.; Fischer, T.

2014-09-01

A large, subsurface oxygen deficiency zone is located in the eastern tropical South Pacific Ocean (ETSP). The large-scale circulation in the eastern equatorial Pacific and off Peru in November/December 2012 shows the influence of the equatorial current system, the eastern boundary currents, and the northern reaches of the subtropical gyre. In November 2012 the Equatorial Undercurrent is centered at 250 m depth, deeper than in earlier observations. In December 2012 the equatorial water is transported southeastward near the shelf in the Peru-Chile Undercurrent with a mean transport of 1.6 Sv. In the oxygen minimum zone (OMZ) the flow is overlaid with strong eddy activity on the poleward side of the OMZ. Floats with parking depth at 400 m show fast westward flow in the mid-depth equatorial channel and sluggish flow in the OMZ. Floats with oxygen sensors clearly show the passage of eddies with oxygen anomalies. The long-term float observations in the upper ocean lead to a net community production estimate at about 18° S of up to 16.7 mmol C m-3 yr1 extrapolated to an annual rate and 7.7 mmol C m-3 yr-1 for the time period below the mixed layer. Oxygen differences between repeated ship sections are influenced by the Interdecadal Pacific Oscillation, by the phase of El Niño, by seasonal changes, and by eddies and hence have to be interpreted with care. At and south of the equator the decrease in oxygen in the upper ocean since 1976 is related to an increase in nitrate, phosphate, and in part in silicate.

Circulation, eddies, oxygen, and nutrient changes in the eastern tropical South Pacific Ocean

NASA Astrophysics Data System (ADS)

Czeschel, R.; Stramma, L.; Weller, R. A.; Fischer, T.

2015-06-01

A large subsurface oxygen deficiency zone is located in the eastern tropical South Pacific Ocean (ETSP). The large-scale circulation in the eastern equatorial Pacific and off the coast of Peru in November/December 2012 shows the influence of the equatorial current system, the eastern boundary currents, and the northern reaches of the subtropical gyre. In November 2012 the equatorial undercurrent (EUC) is centered at 250 m depth, deeper than in earlier observations. In December 2012, the equatorial water is transported southeastward near the shelf in the Peru-Chile undercurrent (PCUC) with a mean transport of 1.4 Sv. In the oxygen minimum zone (OMZ), the flow is overlaid with strong eddy activity on the poleward side of the OMZ. Floats with parking depth at 400 m show fast westward flow in the mid-depth equatorial channel and sluggish flow in the OMZ. Floats with oxygen sensors clearly show the passage of eddies with oxygen anomalies. The long-term float observations in the upper ocean lead to a net community production estimate at about 18° S of up to 16.7 mmol C m-3 yr-1 extrapolated to an annual rate and 7.7 mmol C m-3 yr-1 for the time period below the mixed layer. Oxygen differences between repeated ship sections are influenced by the Interdecadal Pacific Oscillation (IPO), by the phase of El Niño, by seasonal changes, and by eddies, and hence have to be interpreted with care. At and south of the Equator the decrease in oxygen in the upper ocean since 1976 is related to an increase in nitrate, phosphate, and in part silicate.

Experimental Investigation of Cylindrical Floating Breakwater Performance with different mooring configurations

USDA-ARS?s Scientific Manuscript database

Floating breakwaters are typically used on limited-fetch water bodies, such as lakes, reservoirs, and bays, where wavelengths are relatively short. They are also often preferred for sites with large water level changes. Common uses are to protect small marinas or for shoreline erosion control. While...

Floating Forests: Validation of a Citizen Science Effort to Answer Global Ecological Questions

NASA Astrophysics Data System (ADS)

Rosenthal, I.; Byrnes, J.; Cavanaugh, K. C.; Haupt, A. J.; Trouille, L.; Bell, T. W.; Rassweiler, A.; Pérez-Matus, A.; Assis, J.

2017-12-01

Researchers undertaking long term, large-scale ecological analyses face significant challenges for data collection and processing. Crowdsourcing via citizen science can provide an efficient method for analyzing large data sets. However, many scientists have raised questions about the quality of data collected by citizen scientists. Here we use Floating-Forests (http://floatingforests.org), a citizen science platform for creating a global time series of giant kelp abundance, to show that ensemble classifications of satellite data can ensure data quality. Citizen scientists view satellite images of coastlines and classify kelp forests by tracing all visible patches of kelp. Each image is classified by fifteen citizen scientists before being retired. To validate citizen science results, all fifteen classifications are converted to a raster and overlaid on a calibration dataset generated from previous studies. Results show that ensemble classifications from citizen scientists are consistently accurate when compared to calibration data. Given that all source images were acquired by Landsat satellites, we expect this consistency to hold across all regions. At present, we have over 6000 web-based citizen scientists' classifications of almost 2.5 million images of kelp forests in California and Tasmania. These results are not only useful for remote sensing of kelp forests, but also for a wide array of applications that combine citizen science with remote sensing.

Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design

PubMed Central

Matha, Denis; Sandner, Frank; Molins, Climent; Campos, Alexis; Cheng, Po Wen

2015-01-01

The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar platform as performed within the European KIC AFOSP project is presented. Results from the experimental tests compared to numerical simulations are presented and analysed and show very good agreement for relevant basic dynamic platform properties. Extreme and fatigue loads and cost analysis of the AFOSP system confirm the viability of the presented design process. In summary, the exemplary application of the reduced design and testing methodology for AFOSP confirms that it represents a viable procedure during pre-design of floating offshore wind turbine platforms. PMID:25583870

Investigating the potential of floating mires as record of palaeoenvironmental changes

NASA Astrophysics Data System (ADS)

Zaccone, C.; Adamo, P.; Giordano, S.; Miano, T. M.

2012-04-01

Peat-forming floating mires could provide an exceptional resource for palaeoenvironmental and environmental monitoring studies, as much of their own history, as well as the history of their surrounds, is recorded in their peat deposits. In his Naturalis historia (AD 77-79), Pliny the Elder described floating islands on Lake Vadimonis (now Posta Fibreno Lake, Italy). Actually, a small floating island (ca. 35 m of diameter and 3 m of submerged thickness) still occurs on this calcareous lake fed by karstic springs at the base of the Apennine Mountains. Here the southernmost Italian populations of Sphagnum palustre occur on the small surface of this floating mire known as "La Rota", i.e., a cup-formed core of Sphagnum peat and rhizomes of Helophytes, erratically floating on the water-body of a submerged doline, annexed to the easternmost edge of the lake, characterised by the extension of a large reed bed. Geological evidence point out the existence in the area of a large lacustrine basin since Late Pleistocene. The progressive filling of the lake caused by changing in climatic conditions and neotectonic events, brought about the formation of peat deposits in the area, following different depositional cycles in a swampy environment. Then, a round-shaped portion of fen, originated around lake margins in waterlogged areas, was somehow isolated from the bank and started to float. Coupling data about concentrations and fluxes of several major and trace elements of different origin (i.e., dust particles, volcanic emissions, cosmogenic dusts and marine aerosols), with climate records (plant micro- and macrofossils, pollens, isotopic ratios), biomolecular records (e.g., lipids), detailed age-depth modelling (i.e., 210Pb, 137Cs, 14C), and humification indexes, the present work is hoped to identify and better understand the reliability of this particular "archive", and thus possible relationships between biogeochemical processes occurring in this floating bog and environmental changes.

Does size and buoyancy affect the long-distance transport of floating debris?

NASA Astrophysics Data System (ADS)

Ryan, Peter G.

2015-08-01

Floating persistent debris, primarily made from plastic, disperses long distances from source areas and accumulates in oceanic gyres. However, biofouling can increase the density of debris items to the point where they sink. Buoyancy is related to item volume, whereas fouling is related to surface area, so small items (which have high surface area to volume ratios) should start to sink sooner than large items. Empirical observations off South Africa support this prediction: moving offshore from coastal source areas there is an increase in the size of floating debris, an increase in the proportion of highly buoyant items (e.g. sealed bottles, floats and foamed plastics), and a decrease in the proportion of thin items such as plastic bags and flexible packaging which have high surface area to volume ratios. Size-specific sedimentation rates may be one reason for the apparent paucity of small plastic items floating in the world’s oceans.

Design, Analysis, Hybrid Testing and Orientation Control of a Floating Platform with Counter-Rotating Vertical-Axis Wind Turbines

NASA Astrophysics Data System (ADS)

Kanner, Samuel Adam Chinman

The design and operation of two counter-rotating vertical-axis wind turbines on a floating, semi-submersible platform is studied. The technology, called the Multiple Integrated and Synchronized Turbines (MIST) platform has the potential to reduce the cost of offshore wind energy per unit of installed capacity. Attached to the platform are closely-spaced, counter-rotating turbines, which can achieve a higher power density per planform area because of synergistic interaction effects. The purpose of the research is to control the orientation of the platform and rotational speeds of the turbines by modifying the energy absorbed by each of the generators of the turbines. To analyze the various aspects of the platform and wind turbines, the analysis is drawn from the fields of hydrodynamics, electromagnetics, aerodynamics and control theory. To study the hydrodynamics of the floating platform in incident monochromatic waves, potential theory is utilized, taking into account the slow-drift yaw motion of the platform. Steady, second-order moments that are spatially dependent (i.e., dependent on the platform's yaw orientation relative to the incident waves) are given special attention since there are no natural restoring yaw moment. The aerodynamics of the counter-rotating turbines are studied in collaboration with researchers at the UC Berkeley Mathematics Department using a high-order, implicit, large-eddy simulation. An element flipping technique is utilized to extend the method to a domain with counter-rotating turbines and the effects from the closely-spaced turbines is compared with existing experimental data. Hybrid testing techniques on a model platform are utilized to prove the controllability of the platform in lieu of a wind-wave tank. A 1:82 model-scale floating platform is fabricated and tested at the UC Berkeley Physical-Model Testing Facility. The vertical-axis wind turbines are simulated by spinning, controllable actuators that can be updated in real-time of the model scale. Under certain wind and wave headings, it is possible to control the orientation of the platform in regular waves to maximize the power output from the turbines. A time-domain numerical simulation tool is able to confirm some of the experimental findings, taking into account the decoupled properties of the slow-drift hydrodynamics and wind turbine aerodynamics. Future platform designs are discussed, including the French-based, pre-commercial design from Nenuphar Wind, called the TwinFloat, which is closely related to concepts examined in the thesis.

Testing of a spacecraft model in a combined environment simulator

NASA Technical Reports Server (NTRS)

Staskus, J. V.; Roche, J. C.

1981-01-01

A scale model of a satellite was tested in a large vacuum facility under electron bombardment and vacuum ultraviolet radiation to investigate the charging of dielectric materials on curved surfaces. The model was tested both stationary and rotating relative to the electron sources as well as grounded through one megohm and floating relative to the chamber. Surface potential measurements are presented and compared with the predictions of computer modelling of the stationary tests. Discharge activity observed during the stationary tests is discussed and signals from sensing devices located inside and outside of the model are presented.

Towards High Resolution Numerical Algorithms for Wave Dominated Physical Phenomena

DTIC Science & Technology

2009-01-30

results are scaled as floating point operations per second, obtained by counting the number of floating point additions and multiplications in the...black horizontal line. Perhaps the most striking feature at first is the fact that the memory bandwidth measured for flux lifting transcends this...theoretical peak performance values. For a suitable CPU-limited workload, this means that a single workstation equipped with multiple GPUs can do work that

Can flexibility help you float?

NASA Astrophysics Data System (ADS)

Burton, L. J.; Bush, J. W. M.

2012-10-01

We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum stable plate load and optimal stiffness for weight support. Plates small relative to the capillary length are primarily supported by surface tension, and their weight-bearing potential does not benefit from flexibility. Above a critical size comparable to the capillary length, flexibility assists interfacial flotation. For plates on the order of and larger than the capillary length, deflection from an initially flat shape increases the force resulting from hydrostatic pressure, allowing the plate to support a greater load. In this large plate limit, the shape that bears the most weight is a semicircle, which displaces the most fluid above the plate for a fixed plate length. Exact results for maximum weight-bearing plate shapes are compared to analytic approximations made in the limits of large and small plate sizes. The value of flexibility for floating to a number of biological organisms is discussed in light of our study.

Ambipolar nonvolatile memory based on a quantum-dot transistor with a nanoscale floating gate

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

Che, Yongli; Zhang, Yating, E-mail: yating@tju.edu.cn; Song, Xiaoxian

2016-07-04

Using only solution processing methods, we developed ambipolar quantum-dot (QD) transistor floating-gate memory (FGM) that uses Au nanoparticles as a floating gate. Because of the bipolarity of the active channel of PbSe QDs, the memory could easily trap holes or electrons in the floating gate by programming/erasing (P/E) operations, which could shift the threshold voltage both up and down. As a result, the memory exhibited good programmable memory characteristics: a large memory window (ΔV{sub th} ∼ 15 V) and a long retention time (>10{sup 5 }s). The magnitude of ΔV{sub th} depended on both P/E voltages and the bias voltage (V{sub DS}): ΔV{sub th}more » was a cubic function to V{sub P/E} and linearly depended on V{sub DS}. Therefore, this FGM based on a QD transistor is a promising alternative to its inorganic counterparts owing to its advantages of bipolarity, high mobility, low cost, and large-area production.« less

Marine floating microbial fuel cell involving aerobic biofilm on stainless steel cathodes.

PubMed

Erable, B; Lacroix, R; Etcheverry, L; Féron, D; Delia, M L; Bergel, A

2013-08-01

Here is presented a new design of a floating marine MFC in which the inter-electrode space is constant. This design allows the generation of stable current for applications in environments where the water column is large or subject to fluctuations such as tidal effects. The operation of the first prototype was validated by running a continuous test campaign for 6months. Performance in terms of electricity generation was already equivalent to what is conventionally reported in the literature with basic benthic MFCs despite the identification of a large internal resistance in the proposed design of the floating system. This high internal resistance is mainly explained by poor positioning of the membrane separating the anode compartment from the open seawater. The future objectives are to achieve more consistent performance and a second-generation prototype is now being developed, mainly incorporating a modification of the separator position and a stainless steel biocathode with a large bioavailable surface. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development and calibration of an air-floating six-axis force measurement platform using self-calibration

NASA Astrophysics Data System (ADS)

Huang, Bin; Wang, Xiaomeng; Li, Chengwei; Yi, Jiajing; Lu, Rongsheng; Tao, Jiayue

2016-09-01

This paper describes the design, working principle, as well as calibration of an air-floating six-axis force measurement platform, where the floating plate and nozzles were connected without contact, preventing inter-dimensional coupling and increasing precision significantly. The measurement repeatability error of the force size in the platform is less than 0.2% full scale (FS), which is significantly better than the precision of 1% FS in the six-axis force sensors on the current market. We overcame the difficulties of weight loading device in high-precision calibration by proposing a self-calibration method based on the floating plate gravity and met the calibration precision requirement of 0.02% FS. This study has general implications for the development and calibration of high-precision multi-axis force sensors. In particular, the air-floating six-axis force measurement platform could be applied to the calibration of some special sensors such as flexible tactile sensors and may be used as a micro-nano mechanical assembly platform for real-time assembly force testing.

A randomization approach to handling data scaling in nuclear medicine.

PubMed

Bai, Chuanyong; Conwell, Richard; Kindem, Joel

2010-06-01

In medical imaging, data scaling is sometimes desired to handle the system complexity, such as uniformity calibration. Since the data are usually saved in short integer, conventional data scaling will first scale the data in floating point format and then truncate or round the floating point data to short integer data. For example, when using truncation, scaling of 9 by 1.1 results in 9 and scaling of 10 by 1.1 results in 11. When the count level is low, such scaling may change the local data distribution and affect the intended application of the data. In this work, the authors use an example gated cardiac SPECT study to illustrate the effect of conventional scaling by factors of 1.1 and 1.2. The authors then scaled the data with the same scaling factors using a randomization approach, in which a random number evenly distributed between 0 and 1 is generated to determine how the floating point data will be saved as short integer data. If the random number is between 0 and 0.9, then 9.9 will be saved as 10, otherwise 9. In other words, the floating point value 9.9 will be saved in short integer value as 10 with 90% probability or 9 with 10% probability. For statistical analysis of the performance, the authors applied the conventional approach with rounding and the randomization approach to 50 consecutive gated studies from a clinical site. For the example study, the image reconstructed from the original data showed an apparent perfusion defect at the apex of the myocardium. The defect size was noticeably changed by scaling with 1.1 and 1.2 using the conventional approaches with truncation and rounding. Using the randomization approach, in contrast, the images from the scaled data appeared identical to the original image. Line profile analysis of the scaled data showed that the randomization approach introduced the least change to the data as compared to the conventional approaches. For the 50 gated data sets, significantly more studies showed quantitative differences between the original images and the images from the data scaled by 1.2 using the rounding approach than the randomization approach [46/50 (92%) versus 3/50 (6%), p < 0.05]. Likewise, significantly more studies showed visually noticeable differences between the original images and the images from the data scaled by 1.2 using the rounding approach than randomization [29/50 (58%) versus 1/50 (2%), p < 0.05]. In conclusion, the proposed randomization approach minimizes the scaling-introduced local data change as compared to the conventional approaches. It is preferred for nuclear medicine data scaling.

Ice sheet-ocean interactions and sea level change

NASA Astrophysics Data System (ADS)

Heimbach, Patrick

2014-03-01

Mass loss from the Greenland and Antarctic ice sheets has increased rapidly since the mid-1990s. Their combined loss now accounts for about one-third of global sea level rise. In Greenland, a growing body of evidence points to the marine margins of these glaciers as the region from which this dynamic response originated. Similarly, ice streams in West Antarctica that feed vast floating ice shelves have exhibited large decadal changes. We review observational evidence and present physical mechanisms that might explain the observed changes, in particular in the context of ice sheet-ocean interactions. Processes involve cover 7 orders of magnitudes of scales, ranging from mm boundary-layer processes to basin-scale coupled atmosphere-ocean variability. We discuss observational needs to fill the gap in our mechanistic understanding.

Effect of Trapped Ions on Shielding and Floating Potential of a Dust Grain in a Plasma

NASA Astrophysics Data System (ADS)

Lampe, Martin; Ganguli, Gurudas; Joyce, Glenn; Gavrishchaka, Valeriy

2001-10-01

The problem of electrostatic shielding around a small spherical collector immersed in plasma, and the related problem of electron and ion flow to the collector, date to the origins of plasma physics. Beginning with Mott-Smith and Langmuir (1926), calculations have typically neglected collisions, on the grounds that the mean free path is long compared to shielding length scales, i.e. the Debye length. However, investigators beginning with Bernstein and Rabinowitz (1959) have known that negative-energy trapped ions, created by occasional collisions, might be important. We present an analytic calculation of the density of trapped and untrapped ions, self-consistent with the potential. Under typical conditions for dust grains immersed in a discharge plasma, trapped ions dominate the shielding cloud in steady state, even in the limit of very long mean free path. As a result the shielded potential is different from the results of orbital motion limited theory. Collisions also greatly increase the ion current to the collector, thereby decreasing the floating potential and the grain charge by a factor as large as two to three.

Fabrication of arrayed Si nanowire-based nano-floating gate memory devices on flexible plastics.

PubMed

Yoon, Changjoon; Jeon, Youngin; Yun, Junggwon; Kim, Sangsig

2012-01-01

Arrayed Si nanowire (NW)-based nano-floating gate memory (NFGM) devices with Pt nanoparticles (NPs) embedded in Al2O3 gate layers are successfully constructed on flexible plastics by top-down approaches. Ten arrayed Si NW-based NFGM devices are positioned on the first level. Cross-linked poly-4-vinylphenol (PVP) layers are spin-coated on them as isolation layers between the first and second level, and another ten devices are stacked on the cross-linked PVP isolation layers. The electrical characteristics of the representative Si NW-based NFGM devices on the first and second levels exhibit threshold voltage shifts, indicating the trapping and detrapping of electrons in their NPs nodes. They have an average threshold voltage shift of 2.5 V with good retention times of more than 5 x 10(4) s. Moreover, most of the devices successfully retain their electrical characteristics after about one thousand bending cycles. These well-arrayed and stacked Si NW-based NFGM devices demonstrate the potential of nanowire-based devices for large-scale integration.

Extreme-Scale Algorithms & Software Resilience (EASIR) Architecture-Aware Algorithms for Scalable Performance and Resilience on Heterogeneous Architectures

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

Demmel, James W.

This project addresses both communication-avoiding algorithms, and reproducible floating-point computation. Communication, i.e. moving data, either between levels of memory or processors over a network, is much more expensive per operation than arithmetic (measured in time or energy), so we seek algorithms that greatly reduce communication. We developed many new algorithms for both dense and sparse, and both direct and iterative linear algebra, attaining new communication lower bounds, and getting large speedups in many cases. We also extended this work in several ways: (1) We minimize writes separately from reads, since writes may be much more expensive than reads on emergingmore » memory technologies, like Flash, sometimes doing asymptotically fewer writes than reads. (2) We extend the lower bounds and optimal algorithms to arbitrary algorithms that may be expressed as perfectly nested loops accessing arrays, where the array subscripts may be arbitrary affine functions of the loop indices (eg A(i), B(i,j+k, k+3*m-7, …) etc.). (3) We extend our communication-avoiding approach to some machine learning algorithms, such as support vector machines. This work has won a number of awards. We also address reproducible floating-point computation. We define reproducibility to mean getting bitwise identical results from multiple runs of the same program, perhaps with different hardware resources or other changes that should ideally not change the answer. Many users depend on reproducibility for debugging or correctness. However, dynamic scheduling of parallel computing resources, combined with nonassociativity of floating point addition, makes attaining reproducibility a challenge even for simple operations like summing a vector of numbers, or more complicated operations like the Basic Linear Algebra Subprograms (BLAS). We describe an algorithm that computes a reproducible sum of floating point numbers, independent of the order of summation. The algorithm depends only on a subset of the IEEE Floating Point Standard 754-2008, uses just 6 words to represent a “reproducible accumulator,” and requires just one read-only pass over the data, or one reduction in parallel. New instructions based on this work are being considered for inclusion in the future IEEE 754-2018 floating-point standard, and new reproducible BLAS are being considered for the next version of the BLAS standard.« less

Identification of mothball powder composition by float tests and melting point tests.

PubMed

Tang, Ka Yuen

2018-07-01

The aim of the study was to identify the composition, as either camphor, naphthalene, or paradichlorobenzene, of mothballs in the form of powder or tiny fragments by float tests and melting point tests. Naphthalene, paradichlorobenzene and camphor mothballs were blended into powder and tiny fragments (with sizes <1/10 of the size of an intact mothball). In the float tests, the mothball powder and tiny fragments were placed in water, saturated salt solution and 50% dextrose solution (D50), and the extent to which they floated or sank in the liquids was observed. In the melting point tests, the mothball powder and tiny fragments were placed in hot water with a temperature between 53 and 80 °C, and the extent to which they melted was observed. Both the float and melting point tests were then repeated using intact mothballs. Three emergency physicians blinded to the identities of samples and solutions visually evaluated each sample. In the float tests, paradichlorobenzene powder partially floated and partially sank in all three liquids, while naphthalene powder partially floated and partially sank in water. Naphthalene powder did not sink in D50 or saturated salt solution. Camphor powder floated in all three liquids. Float tests identified the compositions of intact mothball accurately. In the melting point tests, paradichlorobenzene powder melted completely in hot water within 1 min while naphthalene powder and camphor powder did not melt. The melted portions of paradichlorobenzene mothballs were sometimes too small to be observed in 1 min but the mothballs either partially or completely melted in 5 min. Both camphor and naphthalene intact mothballs did not melt in hot water. For mothball powder, the melting point tests were more accurate than the float tests in differentiating between paradichlorobenzene and non-paradichlorobenzene (naphthalene or camphor). For intact mothballs, float tests performed better than melting point tests. Float tests can identify camphor mothballs but melting point tests cannot. We suggest melting point tests for identifying mothball powder and tiny fragments while float tests are recommended for intact mothball and large fragments.

Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design.

PubMed

Matha, Denis; Sandner, Frank; Molins, Climent; Campos, Alexis; Cheng, Po Wen

2015-02-28

The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar platform as performed within the European KIC AFOSP project is presented. Results from the experimental tests compared to numerical simulations are presented and analysed and show very good agreement for relevant basic dynamic platform properties. Extreme and fatigue loads and cost analysis of the AFOSP system confirm the viability of the presented design process. In summary, the exemplary application of the reduced design and testing methodology for AFOSP confirms that it represents a viable procedure during pre-design of floating offshore wind turbine platforms. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

76 FR 52269 - Safety Zone; Port Huron Float Down, St. Clair River, Port Huron, MI

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-22

... various social-media sites in which a large number of persons may float down a segment of the St. Clair... rule would have a significant economic impact on a substantial number of small entities. The term ``small entities'' comprises small businesses, not-for-profit organizations that are independently owned...

Lateral assembly of oxidized graphene flakes into large-scale transparent conductive thin films with a three-dimensional surfactant 4-sulfocalix[4]arene

PubMed Central

Sundramoorthy, Ashok K.; Wang, Yilei; Wang, Jing; Che, Jianfei; Thong, Ya Xuan; Lu, Albert Chee W.; Chan-Park, Mary B.

2015-01-01

Graphene is a promising candidate material for transparent conductive films because of its excellent conductivity and one-carbon-atom thickness. Graphene oxide flakes prepared by Hummers method are typically several microns in size and must be pieced together in order to create macroscopic films. We report a macro-scale thin film fabrication method which employs a three-dimensional (3-D) surfactant, 4-sulfocalix[4]arene (SCX), as a lateral aggregating agent. After electrochemical exfoliation, the partially oxidized graphene (oGr) flakes are dispersed with SCX. The SCX forms micelles, which adsorb on the oGr flakes to enhance their dispersion, also promote aggregation into large-scale thin films under vacuum filtration. A thin oGr/SCX film can be shaved off from the aggregated oGr/SCX cake by immersing the cake in water. The oGr/SCX thin-film floating on the water can be subsequently lifted from the water surface with a substrate. The reduced oGr (red-oGr) films can be as thin as 10−20 nm with a transparency of >90% and sheet resistance of 890 ± 47 kΩ/sq. This method of electrochemical exfoliation followed by SCX-assisted suspension and hydrazine reduction, avoids using large amounts of strong acid (unlike Hummers method), is relatively simple and can easily form a large scale conductive and transparent film from oGr/SCX suspension. PMID:26040436

Floating aerial 3D display based on the freeform-mirror and the improved integral imaging system

NASA Astrophysics Data System (ADS)

Yu, Xunbo; Sang, Xinzhu; Gao, Xin; Yang, Shenwu; Liu, Boyang; Chen, Duo; Yan, Binbin; Yu, Chongxiu

2018-09-01

A floating aerial three-dimensional (3D) display based on the freeform-mirror and the improved integral imaging system is demonstrated. In the traditional integral imaging (II), the distortion originating from lens aberration warps elemental images and degrades the visual effect severely. To correct the distortion of the observed pixels and to improve the image quality, a directional diffuser screen (DDS) is introduced. However, the improved integral imaging system can hardly present realistic images with the large off-screen depth, which limits floating aerial visual experience. To display the 3D image in the free space, the off-axis reflection system with the freeform-mirror is designed. By combining the improved II and the designed freeform optical element, the floating aerial 3D image is presented.

Quality of life associated with perceived stigma and discrimination among the floating population in Shanghai, China: a qualitative study.

PubMed

Wang, Ji-Wei; Cui, Zhi-Ting; Cui, Hong-Wei; Wei, Chang-Nian; Harada, Koichi; Minamoto, Keiko; Ueda, Kimiyo; Ingle, Kapilkumar N; Zhang, Cheng-Gang; Ueda, Atsushi

2010-12-01

The floating population refers to the large and increasing number of migrants without local household registration status and has become a new demographic phenomenon in China. Most of these migrants move from the rural areas of the central and western parts of China to the eastern and coastal metropolitan areas in pursuit of a better life. The floating population of China was composed of 121 million people in 2000, and this number was expected to increase to 300 million by 2010. Quality of life (QOL) studies of the floating population could provide a critical starting point for recognizing the potential of regions, cities and local communities to improve QOL. This study explored the construct of QOL of the floating population in Shanghai, China. We conducted eight focus groups with 58 members of the floating population (24 males and 34 females) and then performed a qualitative thematic analysis of the interviews. The following five QOL domains were identified from the analysis: personal development, jobs and career, family life, social relationships and social security. The results indicated that stigma and discrimination permeate these life domains and influence the framing of life expectations. Proposals were made for reducing stigma and discrimination against the floating population to improve the QOL of this population.

Long-Term Observations of Ocean Biogeochemistry with Nitrate and Oxygen Sensors in Apex Profiling Floats

NASA Astrophysics Data System (ADS)

Johnson, K. S.; Coletti, L.; Jannasch, H.; Martz, T.; Swift, D.; Riser, S.

2008-12-01

Long-term, autonomous observations of ocean biogeochemical cycles are now feasible with chemical sensors in profiling floats. These sensors will enable decadal-scale observations of trends in global ocean biogeochemical cycles. Here, we focus on measurements on nitrate and dissolved oxygen. The ISUS (In Situ Ultraviolet Spectrophotometer) optical nitrate sensor has been adapted to operate in a Webb Research, Apex profiling float. The Apex float is of the type used in the Argo array and is designed for multi-year, expendable deployments in the ocean. Floats park at 1000 m depth and make 60 nitrate and oxygen measurements at depth intervals ranging from 50 m below 400 m to 5 m in the upper 100 m as they profile to the surface. All data are transmitted to shore using the Iridium telemetry system and they are available on the Internet in near-real time. Floats equipped with ISUS and an Aanderaa oxygen sensor are capable of making 280 vertical profiles from 1000 m. At a 5 day cycle time, the floats should have nearly a four year endurance. Three floats have now been deployed at the Hawaii Ocean Time series station (HOT), Ocean Station Papa (OSP) in the Gulf of Alaska and at 50 South, 30 East in the Southern Ocean. Two additional floats are designated for deployment at the Bermuda Atlantic Time Series station (BATS) and in the Drake Passage. The HOT float has made 56 profiles over 260 days and should continue operating for 3 more years. Nitrate concentrations are in excellent agreement with the long-term mean observed at HOT. No significant long-term drift in sensor response has occurred. A variety of features have been observed in the HOT nitrate data that are linked to contemporaneous changes in oxygen production and mesoscale dynamics. The impacts of these features will be briefly described. The Southern Ocean float has operated for 200 days and is now observing reinjection of nitrate into surface waters as winter mixing occurs(surface nitrate > 24 micromolar). We expect that the OSP and Southern Ocean floats will provide a quantitative measurement of the timing and magnitude of the spring bloom via the drawdown of surface nitrate. We are funded through NSF and NOPP to continue float deployments at HOT, BATS, OSP and the Southern Ocean for the next 3 years and to refine the sensor so it can be offered as a commercial option for all float users. New sensors in development for float deployments include a stable ISFET pH sensor.

Next generation sensing platforms for extended deployments in large-scale, multidisciplinary, adaptive sampling and observational networks

NASA Astrophysics Data System (ADS)

Cross, J. N.; Meinig, C.; Mordy, C. W.; Lawrence-Slavas, N.; Cokelet, E. D.; Jenkins, R.; Tabisola, H. M.; Stabeno, P. J.

2016-12-01

New autonomous sensors have dramatically increased the resolution and accuracy of oceanographic data collection, enabling rapid sampling over extremely fine scales. Innovative new autonomous platofrms like floats, gliders, drones, and crawling moorings leverage the full potential of these new sensors by extending spatiotemporal reach across varied environments. During 2015 and 2016, The Innovative Technology for Arctic Exploration Program at the Pacific Marine Environmental Laboratory tested several new types of fully autonomous platforms with increased speed, durability, and power and payload capacity designed to deliver cutting-edge ecosystem assessment sensors to remote or inaccessible environments. The Expendable Ice-Tracking (EXIT) gloat developed by the NOAA Pacific Marine Environmental Laboratory (PMEL) is moored near bottom during the ice-free season and released on an autonomous timer beneath the ice during the following winter. The float collects a rapid profile during ascent, and continues to collect critical, poorly-accessible under-ice data until melt, when data is transmitted via satellite. The autonomous Oculus sub-surface glider developed by the University of Washington and PMEL has a large power and payload capacity and an enhanced buoyancy engine. This 'coastal truck' is designed for the rapid water column ascent required by optical imaging systems. The Saildrone is a solar and wind powered ocean unmanned surface vessel (USV) developed by Saildrone, Inc. in partnership with PMEL. This large-payload (200 lbs), fast (1-7 kts), durable (46 kts winds) platform was equipped with 15 sensors designed for ecosystem assessment during 2016, including passive and active acoustic systems specially redesigned for autonomous vehicle deployments. The senors deployed on these platforms achieved rigorous accuracy and precision standards. These innovative platforms provide new sampling capabilities and cost efficiencies in high-resolution sensor deployment, including reconnaissance for annual fisheries and marine mammal surveys; better linkages between sustained observing platforms; and adaptive deployments that can easily target anomalies as they arise.

Evaluating Southern Ocean Carbon Eddy-Pump From Biogeochemical-Argo Floats

NASA Astrophysics Data System (ADS)

Llort, Joan; Langlais, C.; Matear, R.; Moreau, S.; Lenton, A.; Strutton, Peter G.

2018-02-01

The vertical transport of surface water and carbon into ocean's interior, known as subduction, is one of the main mechanisms through which the ocean influences Earth's climate. New instrumental approaches have shown the occurrence of localized and intermittent subduction episodes associated with small-scale ocean circulation features. These studies also revealed the importance of such events for the export of organic matter, the so-called eddy-pump. However, the transient and localized nature of episodic subduction hindered its large-scale evaluation to date. In this work, we present an approach to detect subduction events at the scale of the Southern Ocean using measurements collected by biogeochemical autonomous floats (BGCArgo). We show how subduction events can be automatically identified as anomalies of spiciness and Apparent Oxygen Utilization (AOU) below the mixed layer. Using this methodology over more than 4,000 profiles, we detected 40 subduction events unevenly distributed across the Sothern Ocean. Events were more likely found in hot spots of eddy kinetic energy (EKE), downstream major bathymetric features. Moreover, the bio-optical measurements provided by BGCArgo allowed measuring the amount of Particulate Organic Carbon (POC) being subducted and assessing the contribution of these events to the total downward carbon flux at 100 m (EP100). We estimated that the eddy-pump represents less than 19% to the EP100 in the Southern Ocean, although we observed particularly strong events able to locally duplicate the EP100. This approach provides a novel perspective on where episodic subduction occurs that will be naturally improved as BGCArgo observations continue to increase.

Upsets in Erased Floating Gate Cells With High-Energy Protons

DOE PAGES

Gerardin, S.; Bagatin, M.; Paccagnella, A.; ...

2017-01-01

We discuss upsets in erased floating gate cells, due to large threshold voltage shifts, using statistical distributions collected on a large number of memory cells. The spread in the neutral threshold voltage appears to be too low to quantitatively explain the experimental observations in terms of simple charge loss, at least in SLC devices. The possibility that memories exposed to high energy protons and heavy ions exhibit negative charge transfer between programmed and erased cells is investigated, although the analysis does not provide conclusive support to this hypothesis.

Wave-induced drift of large floating sheets

NASA Astrophysics Data System (ADS)

Christensen, K. H.; Weber, J. E.

In this article we study the wave-induced drift of large, flexible shallow floating objects, referred to as sheets. When surface waves propagate through a sheet, they provide a mean stress on the sheet, resulting in a mean drift. In response, the sheet generates an Ekman current. The drift velocity of the sheet is determined by (i) the wave-induced stress, (ii) the viscous stress due to the Ekman current, and (iii) the Coriolis force. The sheet velocity and the current beneath the sheet are determined for constant and depth-varying eddy viscosities.

Spatio-temporal characteristics of large scale motions in a turbulent boundary layer from direct wall shear stress measurement

NASA Astrophysics Data System (ADS)

Pabon, Rommel; Barnard, Casey; Ukeiley, Lawrence; Sheplak, Mark

2016-11-01

Particle image velocimetry (PIV) and fluctuating wall shear stress experiments were performed on a flat plate turbulent boundary layer (TBL) under zero pressure gradient conditions. The fluctuating wall shear stress was measured using a microelectromechanical 1mm × 1mm floating element capacitive shear stress sensor (CSSS) developed at the University of Florida. The experiments elucidated the imprint of the organized motions in a TBL on the wall shear stress through its direct measurement. Spatial autocorrelation of the streamwise velocity from the PIV snapshots revealed large scale motions that scale on the order of boundary layer thickness. However, the captured inclination angle was lower than that determined using the classic method by means of wall shear stress and hot-wire anemometry (HWA) temporal cross-correlations and a frozen field hypothesis using a convection velocity. The current study suggests the large size of these motions begins to degrade the applicability of the frozen field hypothesis for the time resolved HWA experiments. The simultaneous PIV and CSSS measurements are also used for spatial reconstruction of the velocity field during conditionally sampled intense wall shear stress events. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138.

A Self-Powered Fast-Sampling Profiling Float in support of a Mesoscale Ocean Observing System in the Western North Pacific

NASA Astrophysics Data System (ADS)

Valdez, T.; Chao, Y.; Davis, R. E.; Jones, J.

2012-12-01

This talk will describe a new self-powered profiling float that can perform fast sampling over the upper ocean for long durations in support of a mesoscale ocean observing system in the Western North Pacific. The current state-of-the-art profiling floats can provide several hundreds profiles for the upper ocean every ten days. To quantify the role of the upper ocean in modulating the development of Typhoons requires at least an order of magnitude reduction for the sampling interval. With today's profiling float and battery technology, a fast sampling of one day or even a few hours will reduce the typical lifetime of profiling floats from years to months. Interactions between the ocean and typhoons often involves mesoscale eddies and fronts, which require a dense array of floats to reveal the 3-dimensional structure. To measure the mesoscale ocean over a large area like the Western North Pacific therefore requires a new technology that enables fast sampling and long duration at the same time. Harvesting the ocean renewable energy associated with the vertical temperature differentials has the potential to power profiling floats with fast sampling over long durations. Results from the development and deployment of a prototype self-powered profiling float (known as SOLO-TREC) will be presented. With eight hours sampling in the upper 500 meters, the upper ocean temperature and salinity reveal pronounced high frequency variations. Plans to use the SOLO-TREC technology in support of a dense array of fast sampling profiling floats in the Western North Pacific will be discussed.

Local and Regional Determinants of an Uncommon Functional Group in Freshwater Lakes and Ponds

PubMed Central

McCann, Michael James

2015-01-01

A combination of local and regional factors and stochastic forces is expected to determine the occurrence of species and the structure of communities. However, in most cases, our understanding is incomplete, with large amounts of unexplained variation. Using functional groups rather than individual species may help explain the relationship between community composition and conditions. In this study, I used survey data from freshwater lakes and ponds to understand factors that determine the presence of the floating plant functional group in the northeast United States. Of the 176 water bodies surveyed, 104 (59.1%) did not contain any floating plant species. The occurrence of this functional group was largely determined by local abiotic conditions, which were spatially autocorrelated across the region. A model predicting the presence of the floating plant functional group performed similarly to the best species-specific models. Using a permutation test, I also found that the observed prevalence of floating plants is no different than expected by random assembly from a species pool of its size. These results suggest that the size of the species pool interacts with local conditions in determining the presence of a functional group. Nevertheless, a large amount of unexplained variation remains, attributable to either stochastic species occurrence or incomplete predictive models. The simple permutation approach in this study can be extended to test alternative models of community assembly. PMID:26121636

High-resolution Bio-Argo and Argo Measurements to Reveal Specific Oceanic Processes.

NASA Astrophysics Data System (ADS)

Poteau, A.; Claustre, H.; Briggs, N.; D'Ortenzio, F.; Schmechtig, C.; Prieur, L. M.; Boss, E.

2016-02-01

Together with temperature and salinity measurements, Bio-Argo profiling floats now measure a significant range of biogeochemical (e.g. O2, NO3) and bio-optical variables (Chla, backscattering coefficient and radiometry). To transmit the very large amount of data acquired by this new generation of floats, it was required to substitute the Argos telemetry (Argo program) with iridium telemetry. The obvious consequence is not only a much greater flexibly on data transmission but also on data acquisition thanks to the two-way communication allowed by iridium. Our group has now deployed and managed over 100 Bio-Argo floats of this type. In particular we have set up high-resolution mode of acquisition for certain periods of time or for dedicated portions of the water column. Here we illustrate with three examples the potential of conducting high-resolution measurement to identify and explore certain oceanic processes. (1) High resolution measurements of pressure, temperature and salinity (every 2 s) when the float is finishing its ascent (without any pump action) in the upper 10 m layer are analyzed with respect to sea state. We particularly focus on the study of the speed anomaly as compared to a nominal speed expected for a calm sea state. By comparison between speed anomaly of a float in the Mediterranean Sea and concurrent sea state measurements by a weather buoy in the same area, we suggest that float behaviour can be an indicator of sea state. (2) Each year, in response to springtime phytoplankton blooms, the resolution of bio-optical variables (backscattering and Chla) in the top 1000 m was increased to at least 1 m (every 10 s) for all floats in the North Atlantic and Southern Ocean. This resolution allowed accurate estimation of the concentration of large phytoplankton aggregates and revealed systematic differences in bulk aggregate sinking rate between ocean basins. (3) Finally we continuously record all the variables at a 10 min resolution during the float drift at 1000m. This allows us to characterize some events at this depth that can be related to bottom currents, high mixing or massive export of aggregates.

Wind tunnel research comparing lateral control devices, particularly at high angles of attack XI : various floating tip ailerons on both rectangular and tapered wings

NASA Technical Reports Server (NTRS)

Weick, Fred E; Harris, Thomas A

1933-01-01

Discussed here are a series of systematic tests being conducted to compare different lateral control devices with particular reference to their effectiveness at high angles of attack. The present tests were made with six different forms of floating tip ailerons of symmetrical section. The tests showed the effect of the various ailerons on the general performance characteristics of the wing, and on the lateral controllability and stability characteristics. In addition, the hinge moments were measured for the most interesting cases. The results are compared with those for a rectangular wing with ordinary ailerons and also with those for a rectangular wing having full-chord floating tip ailerons. Practically all the floating tip ailerons gave satisfactory rolling moments at all angles of attack and at the same time gave no adverse yawing moments of appreciable magnitude. The general performance characteristics with the floating tip ailerons, however, were relatively poor, especially the rate of climb. None of the floating tip ailerons entirely eliminated the auto rotational moments at angles of attack above the stall, but all of them gave lower moments than a plain wing. Some of the floating ailerons fluttered if given sufficiently large deflection, but this could have been eliminated by moving the hinge axis of the ailerons forward. Considering all points including hinge moments, the floating tip ailerons on the wing with 5:1 taper are probably the best of those which were tested.

Modelling large floating bodies in urban area flash-floods via a Smoothed Particle Hydrodynamics model

NASA Astrophysics Data System (ADS)

Albano, Raffaele; Sole, Aurelia; Mirauda, Domenica; Adamowski, Jan

2016-10-01

Large debris, including vehicles parked along floodplains, can cause severe damage and significant loss of life during urban area flash-floods. In this study, the authors validated and applied the Smoothed Particle Hydrodynamics (SPH) model, developed in Amicarelli et al. (2015), which reproduces in 3D the dynamics of rigid bodies driven by free surface flows, to the design of flood mitigation measures. To validate the model, the authors compared the model's predictions to the results of an experimental setup, involving a dam breach that strikes two fixed obstacles and three transportable floating bodies. Given the accuracy of the results, in terms of water depth over time and the time history of the bodies' movements, the SPH model explored in this study was used to analyse the mitigation efficiency of a proposed structural intervention - the use of small barriers (groynes) to prevent the transport of floating bodies. Different groynes configurations were examined to identify the most appropriate design and layout for urban area flash-flood damage mitigation. The authors found that groynes positioned upstream and downstream of each floating body can be effective as a risk mitigation measure for damage resulting from their movement.

Formulation and evaluation of gastroretentive microballoons containing baclofen for a floating oral controlled drug delivery system.

PubMed

Dube, T S; Ranpise, N S; Ranade, A N

2014-01-01

The objective of the present study was to fabricate and evaluate a multiparticulate oral gastroretentive dosage form of baclofen characterized by a central large cavity (hollow core) promoting unmitigated floatation with practical applications to alleviate the signs and symptoms of spasticity and muscular rigidity. Solvent diffusion and evaporation procedure were applied to prepare floating microspheres with a central large cavity using various combinations of ethylcellulose (release retardant) and HPMC K4M (release modifier) dissolved in a mixture of dichloromethane and methanol (2:1). The obtained microspheres (700-1000 µm) exhibit excellent floating ability (86 ± 2.00%) and release characteristics with entrapment efficiency of 95.2 ± 0.32%. Microspheres fabricated with ethylcellulose to HPMC K4M in the ratio 8.5:1.5 released 98.67% of the entrapped drug in 12 h. Muscle relaxation caused by baclofen microspheres impairs the rotarod performance for more than 12 h. Abdominal X-ray images showed that the gastroretention period of the floating barium sulfate- labeled microspheres was no less than 10 h. The buoyant baclofen microspheres provide a promising gastroretentive drug delivery system to deliver baclofen in spastic patients with a sustained release rate.

Moored offshore structures - evaluation of forces in elastic mooring lines

NASA Astrophysics Data System (ADS)

Crudu, L.; Obreja, D. C.; Marcu, O.

2016-08-01

In most situations, the high frequency motions of the floating structure induce important effects in the mooring lines which affect also the motions of the structure. The experience accumulated during systematic experimental tests and calculations, carried out for different moored floating structures, showed a complex influence of various parameters on the dynamic effects. Therefore, it was considered that a systematic investigation is necessary. Due to the complexity of hydrodynamics aspects of offshore structures behaviour, experimental tests are practically compulsory in order to be able to properly evaluate and then to validate their behaviour in real sea. Moreover the necessity to carry out hydrodynamic tests is often required by customers, classification societies and other regulatory bodies. Consequently, the correct simulation of physical properties of the complex scaled models becomes a very important issue. The paper is investigating such kind of problems identifying the possible simplification, generating different approaches. One of the bases of the evaluation has been found consideringtheresults of systematic experimental tests on the dynamic behaviour of a mooring chain reproduced at five different scales. Dynamic effects as well as the influences of the elasticity simulation for 5 different scales are evaluated together. The paper presents systematic diagrams and practical results for a typical moored floating structure operating as pipe layer based on motion evaluations and accelerations in waves.

Channel-Like Bottom Features and High Bottom Melt Rates of Petermann Gletscher's Floating Tongue in Northwestern Greenland

NASA Astrophysics Data System (ADS)

Steffen, K.; Huff, R. D.; Cullen, N.; Rignot, E.; Stewart, C.; Jenkins, A.

2003-12-01

Petermann Gletscher is the largest and most influential outlet glacier in central northern Greenland. Located at 81 N, 60 W, it drains an area of 71,580 km2, with a discharge of 12 cubic km of ice per year into the Arctic Ocean. We finished a second field season in spring 2003 collecting in situ data on local climate, ice velocity, strain rates, ice thickness profiles and bottom melt rates of the floating ice tongue. Last years findings have been confirmed that large channels of several hundred meters in depth at the underside of the floating ice tongue are running roughly parallel to the flow direction. We mapped these channels using ground penetrating radar at 25 MHz frequency and multi-phase radar in profiling mode over half of the glacier's width. In addition, NASA airborne laser altimeter data was collected along and cross-glacier for accurate assessment of surface topography. We will present a 3-D model of the floating ice tongue and provide hypothesis of the origin and mechanism that caused these large ice channels at the bottom of the floating ice tongue. Multi-phase radar point measurements revealed interesting results of bottom melt rates, which exceed all previous estimates. It is worth mentioned that the largest bottom melt rates were not found at the grounding line, which is common on ice shelves in the Antarctica. In addition, GPS tidal motion has been measured over one lunar cycle at the flex zone and on the free floating ice tongue and the result will be compared to historic measurements made at the beginning of last century. The surface climate has been recorded by two automatic weather stations over a 12 month period, and the local climate of this remote region will be presented.

Mesoscale variability of water masses in the Arabian Sea as revealed by ARGO floats

NASA Astrophysics Data System (ADS)

Carton, X.; L'Hegaret, P.

2011-06-01

By analysing ARGO float data over the last four years, some aspects of the mesoscale variability of water masses in the Arabian Sea are described. The Red Sea Water outflow is strong in the Southwestern Gulf of Aden, in particular when a cyclonic gyre predominates in this region. Salinities of 36.5 and temperatures of 16 °C are found there between 600 and 1000 m depths. The Red Sea Water is more dilute in the eastern part of the Gulf, and fragments of this water mass can be advected offshore across the gulf or towards its northern coast by the regional gyres. The Red Sea Water outflow is also detected along the northeastern coast of Socotra, and fragments of RSW are found between one and three degrees of latitude north of this island. In the whole Gulf of Aden, the correlation between the deep motions of the floats and the SSH measured by altimetry is strong, at regional scale. The finer scale details of the float trajectories are more often related to the anomalous water masses that they encounter. The Persian Gulf Water (PGW) is found in the float profiles near Ras ash Sharbatat (near 57° E, 18° N), again with 36.5 in salinity and about 18-19 °C in temperature. These observations were achieved in winter when the southwestward monsoon currents can advect PGW along the South Arabian coast. Fragments of PGW are found in the Arabian Sea between 18 and 20° N and 63 and 65° E, showing that this water mass can escape the Gulf of Oman southeastward, in particular during summer.

Porosity inside a metal casting

NASA Technical Reports Server (NTRS)

2003-01-01

Pores and voids often form in metal castings on Earth (above) making them useless. A transparent material that behaves at a large scale in microgravity the way that metals behave at the microscopic scale on Earth, will help show how voids form and learn how to prevent them. Scientists are using the microgravity environment on the International Space Station to study how these bubbles form, move and interact. The Pore Formation and Mobility Investigation (PFMI) in the Microgravity Science Glovebox aboard the International Space Station uses a transparent material called succinonitrile that behaves like a metal to study this problem. Video images sent to the ground allow scientists to watch the behavior of the bubbles as they control the melting and freezing of the material. The bubbles do not float to the top of the material in microgravity, so they can study their interactions.

Material Science

NASA Image and Video Library

2003-01-22

Pores and voids often form in metal castings on Earth (above) making them useless. A transparent material that behaves at a large scale in microgravity the way that metals behave at the microscopic scale on Earth, will help show how voids form and learn how to prevent them. Scientists are using the microgravity environment on the International Space Station to study how these bubbles form, move and interact. The Pore Formation and Mobility Investigation (PFMI) in the Microgravity Science Glovebox aboard the International Space Station uses a transparent material called succinonitrile that behaves like a metal to study this problem. Video images sent to the ground allow scientists to watch the behavior of the bubbles as they control the melting and freezing of the material. The bubbles do not float to the top of the material in microgravity, so they can study their interactions.

On the subduction of oxygenated surface water in submesoscale cold filaments off Peru.

NASA Astrophysics Data System (ADS)

Thomsen, Soeren; Kanzow, Torsten; Colas, Francois; Echevin, Vincent; Krahmann, Gerd

2015-04-01

The Peruvian upwelling regime is characterized by pronounced submesoscale variability including filaments and sharp density fronts. Submesoscale frontal processes can drive large vertical velocities and enhance vertical tracer fluxes in the upper ocean. The associated high temporal and spatial variability poses a large challenge to observational approaches targeting submesoscale processes. In this study the role of submesoscale processes for both the ventilation of the near-coastal oxygen minimum zone off Peru and the physical-biogeochemical coupling at these scales is investigated. For our study we use satellite based sea surface temperature measurements in combination with multiple high-resolution glider observations of temperature, salinity, oxygen and chlorophyll fluorescence carried out in January and February 2013 off Peru near 14°S during active upwelling. Additionally, high-resolution regional ocean circulation model outputs (ROMS) are analysed. At the beginning of our observations a previously upwelled, productive and highly oxygenated body of water is found within the mixed layer. Subsequently, a cold filament forms and the waters are moved offshore. After the decay of the filament and the relaxation of the upwelling front, the oxygen enriched surface water is found within the previously less oxygenated thermocline suggesting the occurrence of frontal subduction. A numerical model simulation is used to analyse the evolution of passive tracers and Lagrangian floats within several upwelling filaments, whose vertical structure and hydrographic properties agree well with the observations. The simulated temporal evolution of the tracers and floats support our interpretation that the subduction of previously upwelled water indeed occurs within cold filaments off Peru. Filaments are common features within eastern boundary upwelling systems, which all encompass large oxygen minimum zones. However, most state of-the-art large and regional scale physical-biogeochemical ocean models do not resolve submesoscale filaments and the associated downward transport of oxygen and other solutes. Even if the observed subduction event only reaches into the still oxygenated thermocline the associated ventilation mechanism likely influences the shape and depth of the upper boundary of oxygen minimum zones, which would probably be even shallower without this process.

Mathematical modelling of sewage sludge incineration in a bubbling fluidised bed with special consideration for thermally-thick fuel particles.

PubMed

Yang, Yao Bin; Sharifi, Vida; Swithenbank, Jim

2008-11-01

Fluidised bed combustor (FBC) is one of the key technologies for sewage sludge incineration. In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed consisting of a fast-gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The model further improves over previous works by taking into account throughflow inside the bubbles as well as the floating and random movement of the fuel particles inside the bed. Validation against both previous lab-scale experiments and operational data of a large-scale industrial plant was made. Calculation results indicate that combustion split between the bed and the freeboard can range from 60/40 to 90/10 depending on the fuel particle distribution across the bed height under the specific conditions. The bed performance is heavily affected by the variation in sludge moisture level. The response time to variation in feeding rate is different for different parameters, from 6 min for outlet H2O, 10 min for O2, to 34 min for bed temperature.

Programmable Off-The-Shelf cell-enabled GPS loggers optimized for retrieving after being used as a float in large river experiments.

NASA Astrophysics Data System (ADS)

Hut, Rolf; Bogaard, Thom

2017-04-01

Throwing something in a river and seeing how fast it floats downstream is the first thing that every hydrologists does when encountering a new river. Using a collection of floats allows estimation of gauge surface water velocity and dispersion characteristics. To use floats over long (hundreds of kilometers) stretches of river requires either a crew that keeps an eye on the floats (labor intensive) or having high-tech floats that upload their location on regular intervals, such that they can be retrieved at the end of the experiment. GPS floats with communication units have been custom build by scientists before. Connecting GPS units to GSM modems used to require deep knowledge on micro-electronics and network protocols. In this work we present a version that is build using only off-the-shelf electronics that require no deep knowledge of either micro electronics nor network protocols. The new cellular enabled Particle Electron development board made it possible to connect a Sparkfun OpenLog (SD-card based logger) to a GPS tracker with no soldering and little programming. Because scientist can program the device themselves, settings like sample time can be adapted to the needs of specific experiments and additional sensors can be easily added. When writing GPS location every minute to SD and reporting every fifteen minutes online, our logger can run for three days on a single 2200 mAh LiPo battery (provided with the Particle Electron). Cost of components for our logger is less than 150. The durability of our GPS loggers will be tested during a field campaign at the end of January 2017 where 15 floats will float down the Irrawaddy river over a length of more than 200 km, during two days.

[Controlled observation of the efficacy between floating acupuncture at Tianying point and warm-needling therapy for supraspinous ligament injury].

PubMed

Li, Xin-Wei; Shao, Xiao-Mei; Tan, Ke-Ping; Fang, Jian-Qiao

2013-04-01

To compare the efficacy difference in the treatment of supraspinous ligament injury between floating acupuncture at Tianying point and the conventional warm needling therapy. Ninety patients were randomized into a floating acupuncture group and a warm needling group, 45 cases in each one. In the floating acupuncture group, the floating needling technique was adopted at Tianying point. In the warm needling group, the conventional warm needling therapy was applied at Tianying point as the chief point in the prescription. The treatment was given 3 times a week and 6 treatments made one session. The visual analogue scale (VAS) was adopted for pain comparison before and after treatment of the patients in two groups and the efficacy in two groups were assessed. The curative and remarkably effective rate was 81.8% (36/44) in the floating acupuncture group and the total effective rate was 95.5% (42/44), which were superior to 44.2% (19/43) and 79.1% (34/43) in the warm needling group separately (P < 0.01, P < 0.05). VAS score was lower as compared with that before treatment of the patients in two groups (both P < 0.01) and the score in the floating acupuncture group was lower than that in the warm needling group after treatment (P < 0.01). Thirty-six cases were cured and remarkably effective in the floating acupuncture group after treatment, in which 28 cases were cured and remarkably effective in 3 treatments, accounting for 77.8 (28/36), which was apparently higher than 26.3 (5/19) in the warm-needling group (P < 0.01). The floating acupuncture at Tianying point achieves the quick and definite efficacy on supraspinous ligament injury and presents the apparent analgesic effect. The efficacy is superior to the conventional warm-needling therapy.

Are floating algal mats a refuge from hypoxia for estuarine invertebrates?

PubMed Central

Knysh, Kyle M.; Theriault, Emma F.; Pater, Christina C.; Courtenay, Simon C.; van den Heuvel, Michael R.

2017-01-01

Eutrophic aquatic habitats are characterized by the proliferation of vegetation leading to a large standing biomass that upon decomposition may create hypoxic (low-oxygen) conditions. This is indeed the case in nutrient impacted estuaries of Prince Edward Island, Canada, where macroalgae, from the genus Ulva, form submerged ephemeral mats. Hydrological forces and gases released from photosynthesis and decomposition lead to these mats occasionally floating to the water’s surface, henceforth termed floating mats. Here, we explore the hypothesis that floating mats are refugia during periods of sustained hypoxia/anoxia and examine how the invertebrate community responds to it. Floating mats were not always present, so in the first year (2013) sampling was attempted monthly and limited to when both floating and submerged mats occurred. In the subsequent year sampling was weekly, but at only one estuary due to logistical constraints from increased sampling frequency, and was not limited to when both mat types occurred. Water temperature, salinity, and pH were monitored bi-weekly with dissolved oxygen concentration measured hourly. The floating and submerged assemblages shared many of the same taxa but were statistically distinct communities; submerged mats tended to have a greater proportion of benthic animals and floating mats had more mobile invertebrates and insects. In 2014, sampling happened to occur in the weeks before the onset of anoxia, during 113 consecutive hours of sustained anoxia, and for four weeks after normoxic conditions returned. The invertebrate community on floating mats appeared to be unaffected by anoxia, indicating that these mats may be refugia during times of oxygen stress. Conversely, there was a dramatic decrease in animal abundances that remained depressed on submerged mats for two weeks. Cluster analysis revealed that the submerged mat communities from before the onset of anoxia and four weeks after anoxia were highly similar to each other, indicating recovery. When mobile animals were considered alone, there was an exponential relationship between the percentage of animals on floating mats, relative to the total number on both mat types, and hypoxia. The occupation of floating mats by invertebrates at all times, and their dominance there during hypoxia/anoxia, provides support for the hypothesis that floating mats are refugia. PMID:28348927

The 2008 North Atlantic Spring Bloom Experiment II: Autonomous Platforms and Mixed Layer Evolution

NASA Astrophysics Data System (ADS)

Lee, C. M.; D'Asaro, E. A.; Perry, M.; Fennel, K.; Gray, A.; Rehm, E.; Briggs, N.; Sackmann, B. S.; Gudmundsson, K.

2008-12-01

The 2008 North Atlantic Spring Bloom Experiment (NAB08) employed a system of drifting floats, mobile gliders and ship-based measurements to resolve patch-scale physical and biological variability over the 3- month course of an entire bloom. Although both autonomous and ship-based elements were essential to achieving NAB08 goals, the autonomous system provided a novel perspective by employing long-range gliders to repeatedly survey the volume surrounding a drifting Lagrangian float, thus characterizing patch- scale bloom evolution. Integration of physical and biogeochemical sensors (temperature, conductivity, dissolved oxygen, chlorophyll and CDOM fluorescence, light transmission, optical backscatter, spectral light, and nitrate) and development of in situ calibration techniques were required to support this new autonomous approach. Energetic, small-scale eddy activity at the experiment site (southeast of Iceland, near the Joint Global Ocean Flux Study and Marine Light Mixed Layer sites) produced a swift, heterogeneous velocity field that challenged the gliders" operational abilities and drove refinements to the piloting techniques used to maintain float-following surveys. Although intentionally deployed outside of energetic eddies, floats and gliders were rapidly entrained into these features. Floats circulated within eddies near the start and end of the experiment, drifting generally northwest, across the basin, in-between. An eddy sampled late in the deployment provided particularly interesting signatures, with elevated biological signals manifest consistently in one quadrant. As measurements were collected in a parcel-following Lagrangian frame, this suggests energetic small-scale exchange process (such as vertical or lateral mixing) paired with fast-acting biological processes capable of modifying the newly entrained water as it navigates its path around the eddy. Despite this energetic kilometer-scale heterogeneity, broadly distributed platforms appeared to experience similar broad, long-timescale trends. Initial mixed layer depths exceeded 200 m, with gradual shoaling punctuated by periods of rapid, storm-driven deepening. In mid-April, a period of calm weather, rapid restratification and exponentially growing chlorophyll fluorescence marks the bloom's start. Although one-dimensional processes (e.g. diapycnal mixing and solar warming) clearly play important roles in producing the spring bloom, the rate and vertical extent of upper ocean restratification indicate that lateral mixing, perhaps wind- or eddy-driven exchange or the slumping of lateral density contrasts, play a more important role in restratifying the upper ocean. These important trigger events present a severe observational challenge as they take place at small (kilometers) spatial scales, are fully three-dimensional and episodic in time. The NAB08 efforts demonstrate how mobile, autonomous platforms can be exploited to resolve these events and their impact over the course of an entire bloom cycle.

Floating-point function generation routines for 16-bit microcomputers

NASA Technical Reports Server (NTRS)

Mackin, M. A.; Soeder, J. F.

1984-01-01

Several computer subroutines have been developed that interpolate three types of nonanalytic functions: univariate, bivariate, and map. The routines use data in floating-point form. However, because they are written for use on a 16-bit Intel 8086 system with an 8087 mathematical coprocessor, they execute as fast as routines using data in scaled integer form. Although all of the routines are written in assembly language, they have been implemented in a modular fashion so as to facilitate their use with high-level languages.

Floating sample-collection platform with stage-activated automatic water sampler for streams with large variation in stage

USGS Publications Warehouse

Tarte, Stephen R.; Schmidt, A.R.; Sullivan, Daniel J.

1992-01-01

A floating sample-collection platform is described for stream sites where the vertical or horizontal distance between the stream-sampling point and a safe location for the sampler exceed the suction head of the sampler. The platform allows continuous water sampling over the entire storm-runoff hydrogrpah. The platform was developed for a site in southern Illinois.

Plasma sheath structure surrounding a large powered spacecraft

NASA Technical Reports Server (NTRS)

Mandell, M. J.; Jongeward, G. A.; Katz, I.

1984-01-01

Various factors determining the floating potential of a highly biased (about 4-kV) spacecraft in low earth orbit are discussed. While the common rule of thumb (90 percent negative; 10 percent positive) is usually a good guide, different biasing and grounding patterns can lead to high positive potentials. The NASCAP/LEO code can be used to predict spacecraft floating potential for complex three-dimensional spacecraft.

The floating-gate non-volatile semiconductor memory--from invention to the digital age.

PubMed

Sze, S M

2012-10-01

In the past 45 years (from 1967 to 2012), the non-volatile semiconductor memory (NVSM) has emerged from a floating-gate concept to the prime technology driver of the largest industry in the world-the electronics industry. In this paper, we briefly review the historical development of NVSM and project its future trends to the year 2020. In addition, we consider NVSM's wide-range of applications from the digital cellular phone to tablet computer to digital television. As the device dimension is scaled down to the deca-nanometer regime, we expect that many innovations will be made to meet the scaling challenges, and NVSM-inspired technology will continue to enrich and improve our lives for decades to come.

A complete tomography of the Earth's interior with floating seismometers in the oceans: the EarthScope-Oceans

NASA Astrophysics Data System (ADS)

Chen, Y. J.; Nolet, G.

2016-12-01

While the tomography techniques of imaging the earth's interior have been improved significantly over the past three decades the resolution of the resulting 3D images of the earth's interior, particularly the lower mantle, has been severely limited by the lack of seismic stations in the oceans which cover the 2/3 of the earth's surface. But this is going to be changed by the recently developed floating hydrophones called "Mermaids" which, freely floating under the sea surface, can operate as seismometers (see abstract by Nolet et al. in session DI010). These `Mermaids' have recorded (1) teleseismic waves, crucial to provide resolution for tomographic images of the deep mantle beneath oceanic areas, as well as (2) swarms of earthquakes too small to be observed on land, indicative of tectonic motions on oceanic ridges. Transmission is in quasi-real time by satellite (Iridium). A new version of the Mermaid, of much larger capacity, with a lifetime of five to six years is available for deployment. SUSTC in Shenzhen, China, in close collaboration with Geoazur (France), will launch the first stage of a large scale, global network of floating seismometers in the oceans named EarthScope-Oceans in 2017 by setting afloat 50 Mermaids in the Indian Ocean. Japan and other European nations may join the effort, which should reach 500 sensors by 2019 covering the entire world oceans. After that, the robots will be equipped with sophisticated software currently under development, which adds the capacity to juggle up to eight sensors and that has a reprogramming ability even during missions. We then expect the network to become multi-disciplinary and be able to host instruments not only for global seismology but also for biologists, oceanographers, geochemists, meteorologists and others. This new monitoring network will greatly improve our knowledge of acoustic noise pollution, of cetacean populations and their interaction with noise and meteorological conditions in all of the oceans by providing large and continuous data coverage. It will transform the discipline of seismic tomography at sea and improve our understanding of geodynamical processes operating in the deep mantle of the Earth by filling the data gap that currently exists in the oceanic domain.

Experimental investigations on the aerodynamics and aeromechanics of wind turbines for floating offshore applications

NASA Astrophysics Data System (ADS)

Khosravi, Morteza

There are many advantages in floating wind turbines in deep waters, however, there are also significant technological challenges associated with it too. The dynamic excitation of wind and waves can induce excessive motions along each of the 6 degrees of freedom (6-DOF) of the floating platforms. These motions will then be transferred to the turbine, and directly impact the wake characteristics of the floating wind turbines, and consequently the resultant wind loadings and performances of the wind turbines sited in offshore wind farms. In the present study, a comprehensive experimental study was performed to analyze the performance, loading, and the near wake characteristics of a rigid wind turbine model subjected to surge, heave, and pitch motions. The experimental study was performed in a large-scale atmospheric boundary layer wind tunnel with a scaled three-blade Horizontal Axial Wind Turbine model placed in a turbulent boundary layer airflow with similar mean and turbulence characteristics as those over a typical offshore wind farm. The base of the 1:300 scaled model wind turbine was mounted on translation and rotation stages. These stages can be controlled to generate surge, pitch and heave motions to simulate the dynamic motions experienced by floating offshore wind turbines. During the experiments, the velocity scaling method was chosen to maintain the similar velocity ratios (i.e., the ratios of the incoming airflow flow to that of turbine base motion) between the model and the prototype. During the experiments, a high resolution digital particle image velocimetry (PIV) system was used to achieve flow field measurements to quantify the characteristics of the turbulent vortex flow in the near wake of the wind turbine model. Besides conducting ''free run'' PIV measurements to determine the ensemble-averaged statistics of the flow quantities such as mean velocity, Reynolds stress, and turbulence kinetic energy (TKE) distributions in the wake flow, ''phase-locked'' PIV measurements were also performed to elucidate further details about evolution of the unsteady vortex structures in the wake flow in relation to the position of the rotating turbine blades. The effects of the surge, heave, and pitch motions of the wind turbine base on the wake flow characteristics were examined in great details based on the PIV measurements. The findings derived from the present study can be used to improve the understanding of the underlying physics for optimal mechanical design of floating offshore wind turbines, as well as the layout optimization of floating offshore wind farms. Although, the mean power measurement results show little difference between the oscillating turbine and the bottom fixed turbine, but the excessive fluctuations in the power output of the oscillating turbine is anticipated to greatly reduce the power quality of such floating turbines. The load measurements also show substantial amount of difference both in terms of mean and the fluctuating components. The results of the wake study reveal that the wake of a wind turbine subjected to base motions, is highly dependent on which direction the turbine is oscillating. In the case of the moving turbine, the wake accelerates as the turbine is moving with the flow, hence, reducing the power extraction by the turbine. A decrease in Reynolds shear stress and the turbulent kinetic energy production was noted as the turbine was oscillating with the flow. However, as the turbine was moving into the flow, these effects reverse, and causes a deceleration in the wake of the moving turbine, hence increases the power production by the turbine, and increase the Reynolds shear stress and the turbulent kinetic energy. Finally, The wake flow field (x/D < 2.5) measurements behind a two-bladed Darrieus type VAWT were also carried out by using a high-resolution PIV system, and the results obtained at two different horizontal (x-y) planes, at the equator height (H/2) and above the equator height (3H/4), for four different tip speed ratios (lambda = 2, 2.5, 3 and 3.5) of the VAWT were then evaluated and compared. The wake of the VAWT is found to be significantly different to that of the HAWT's. At lower tip-speed-ratio (i.e. TSR 2) the wake tends to be very asymmetric and skewed with relatively higher amount of momentum in the wake in comparison to higher tip-speed ratios (i.e. 3 or 3.5). As tip-speed ratio increases, there is a tendency in flow stagnation in the wake and eventually flow reversal would occur at higher tip-speed-ratios. The wake dynamics (i.e., the instabilities inherent in VAWT) behind the VAWTs would lead to a much faster wake recovery in comparison to the HAWTs.

Hierarchical Nearest-Neighbor Gaussian Process Models for Large Geostatistical Datasets.

PubMed

Datta, Abhirup; Banerjee, Sudipto; Finley, Andrew O; Gelfand, Alan E

2016-01-01

Spatial process models for analyzing geostatistical data entail computations that become prohibitive as the number of spatial locations become large. This article develops a class of highly scalable nearest-neighbor Gaussian process (NNGP) models to provide fully model-based inference for large geostatistical datasets. We establish that the NNGP is a well-defined spatial process providing legitimate finite-dimensional Gaussian densities with sparse precision matrices. We embed the NNGP as a sparsity-inducing prior within a rich hierarchical modeling framework and outline how computationally efficient Markov chain Monte Carlo (MCMC) algorithms can be executed without storing or decomposing large matrices. The floating point operations (flops) per iteration of this algorithm is linear in the number of spatial locations, thereby rendering substantial scalability. We illustrate the computational and inferential benefits of the NNGP over competing methods using simulation studies and also analyze forest biomass from a massive U.S. Forest Inventory dataset at a scale that precludes alternative dimension-reducing methods. Supplementary materials for this article are available online.

Hierarchical Nearest-Neighbor Gaussian Process Models for Large Geostatistical Datasets

PubMed Central

Datta, Abhirup; Banerjee, Sudipto; Finley, Andrew O.; Gelfand, Alan E.

2018-01-01

Spatial process models for analyzing geostatistical data entail computations that become prohibitive as the number of spatial locations become large. This article develops a class of highly scalable nearest-neighbor Gaussian process (NNGP) models to provide fully model-based inference for large geostatistical datasets. We establish that the NNGP is a well-defined spatial process providing legitimate finite-dimensional Gaussian densities with sparse precision matrices. We embed the NNGP as a sparsity-inducing prior within a rich hierarchical modeling framework and outline how computationally efficient Markov chain Monte Carlo (MCMC) algorithms can be executed without storing or decomposing large matrices. The floating point operations (flops) per iteration of this algorithm is linear in the number of spatial locations, thereby rendering substantial scalability. We illustrate the computational and inferential benefits of the NNGP over competing methods using simulation studies and also analyze forest biomass from a massive U.S. Forest Inventory dataset at a scale that precludes alternative dimension-reducing methods. Supplementary materials for this article are available online. PMID:29720777

Downscaling ocean conditions with application to the Gulf of Maine, Scotian Shelf and adjacent deep ocean

NASA Astrophysics Data System (ADS)

Katavouta, Anna; Thompson, Keith

2017-04-01

A high resolution regional model (1/36 degree) of the Gulf of Maine, Scotian Shelf and adjacent deep ocean (GoMSS) is developed to downscale ocean conditions from an existing global operational system. First, predictions from the regional GoMSS model in a one-way nesting set up are evaluated using observations from multiple sources including satellite-borne sensors of surface temperature and sea level, CTDs, Argo floats and moored current meters. It is shown that on the shelf, the regional model predicts more realistic fields than the global system because it has higher resolution and includes tides that are absent from the global system. However, in deep water the regional model misplaces deep ocean eddies and meanders associated with the Gulf Stream. This is because of unrealistic internally generated variability (associated with the one-way nesting set up) that leads to decoupling of the regional model from the global system in the deep water. To overcome this problem, the large scales (length scales > 90 km) of the regional model are spectrally nudged towards the global system fields. This leads to more realistic predictions off the shelf. Wavenumber spectra show that even though spectral nudging constrains the large scales, it does not suppress the variability on small scales; on the contrary, it favours the formation of eddies with length scales below the cut-off wavelength of the spectral nudging.

Weathering of field-collected floating and stranded Macondo oils during and shortly after the Deepwater Horizon oil spill.

PubMed

Stout, Scott A; Payne, James R; Emsbo-Mattingly, Stephen D; Baker, Gregory

2016-04-15

Chemical analysis of large populations of floating (n=62) and stranded (n=1174) Macondo oils collected from the northern Gulf of Mexico sea surface and shorelines during or within seven weeks of the end of the Deepwater Horizon oil spill demonstrates the range, rates, and processes affecting surface oil weathering. Oil collected immediately upon reaching the sea surface had already lost most mass below n-C8 from dissolution of soluble aliphatics, monoaromatics, and naphthalenes during the oil's ascent with further reductions extending up to n-C13 due to the onset of evaporation. With additional time, weathering of the floating and stranded oils advanced with total PAH (TPAH50) depletions averaging 69±23% for floating oils and 94±3% for stranded oils caused by the combined effects of evaporation, dissolution, and photo-oxidation, the latter of which also reduced triaromatic steroid biomarkers. Biodegradation was not evident among the coalesced floating oils studied, but had commenced in some stranded oils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Seismic monitoring in the oceans by autonomous floats.

PubMed

Sukhovich, Alexey; Bonnieux, Sébastien; Hello, Yann; Irisson, Jean-Olivier; Simons, Frederik J; Nolet, Guust

2015-08-20

Our understanding of the internal dynamics of the Earth is largely based on images of seismic velocity variations in the mantle obtained with global tomography. However, our ability to image the mantle is severely hampered by a lack of seismic data collected in marine areas. Here we report observations made under different noise conditions (in the Mediterranean Sea, the Indian and Pacific Oceans) by a submarine floating seismograph, and show that such floats are able to fill the oceanic data gap. Depending on the ambient noise level, the floats can record between 35 and 63% of distant earthquakes with a moment magnitude M≥6.5. Even magnitudes <6.0 can be successfully observed under favourable noise conditions. The serendipitous recording of an earthquake swarm near the Indian Ocean triple junction enabled us to establish a threshold magnitude between 2.7 and 3.4 for local earthquakes in the noisiest of the three environments.

Seismic monitoring in the oceans by autonomous floats

PubMed Central

Sukhovich, Alexey; Bonnieux, Sébastien; Hello, Yann; Irisson, Jean-Olivier; Simons, Frederik J.; Nolet, Guust

2015-01-01

Our understanding of the internal dynamics of the Earth is largely based on images of seismic velocity variations in the mantle obtained with global tomography. However, our ability to image the mantle is severely hampered by a lack of seismic data collected in marine areas. Here we report observations made under different noise conditions (in the Mediterranean Sea, the Indian and Pacific Oceans) by a submarine floating seismograph, and show that such floats are able to fill the oceanic data gap. Depending on the ambient noise level, the floats can record between 35 and 63% of distant earthquakes with a moment magnitude M≥6.5. Even magnitudes <6.0 can be successfully observed under favourable noise conditions. The serendipitous recording of an earthquake swarm near the Indian Ocean triple junction enabled us to establish a threshold magnitude between 2.7 and 3.4 for local earthquakes in the noisiest of the three environments. PMID:26289598

Clarithromycin highly-loaded gastro-floating fine granules prepared by high-shear melt granulation can enhance the efficacy of Helicobacter pylori eradication.

PubMed

Aoki, Hajime; Iwao, Yasunori; Mizoguchi, Midori; Noguchi, Shuji; Itai, Shigeru

2015-05-01

In an effort to develop a new gastro-retentive drug delivery system (GRDDS) without a large amount of additives, 75% clarithromycin (CAM) loaded fine granules were prepared with three different hydrophobic binders by high-shear melt granulation and their properties were evaluated. Granules containing the higher hydrophobic binder showed sustained drug release and were able to float over 24h. The synchrotron X-ray CT measurement indicated that both the high hydrophobicity of the binder and the void space inside the granules might be involved in their buoyancy. In an in vivo experiment, the floating granules more effectively eradicated Helicobacter pylori than a CAM suspension by remaining in the stomach for a longer period. In short, CAM highly-loaded gastro-floating fine granules can enhance the eradication efficiency of H. pylori compared with CAM alone. Copyright © 2015 Elsevier B.V. All rights reserved.

Arctic ice shelves and ice islands: Origin, growth and disintegration, physical characteristics, structural-stratigraphic variability, and dynamics

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

Jeffries, M.O.

1992-08-01

Ice shelves are thick, floating ice masses most often associated with Antarctica where they are seaward extensions of the grounded Antarctic ice sheet and sources of many icebergs. However, there are also ice shelves in the Arctic, primarily located along the north coast of Ellesmere Island in the Canadian High Arctic. The only ice shelves in North America and the most extensive in the north polar region, the Ellesmere ice shelves originate from glaciers and from sea ice and are the source of ice islands, the tabular icebergs of the Arctic Ocean. The present state of knowledge and understanding ofmore » these ice features is summarized in this paper. It includes historical background to the discovery and early study of ice shelves and ice islands, including the use of ice islands as floating laboratories for polar geophysical research. Growth mechanisms and age, the former extent and the twentieth century disintegration of the Ellesmere ice shelves, and the processes and mechanisms of ice island calving are summarized. Surface features, thickness, thermal regime, and the size, shape, and numbers of ice islands are discussed. The structural-stratigraphic variability of ice islands and ice shelves and the complex nature of their growth and development are described. Large-scale and small-scale dynamics of ice islands are described, and the results of modeling their drift and recurrence intervals are presented. The conclusion identifies some unanswered questions and future research opportunities and needs. 97 refs., 18 figs.« less

The Large-Scale Deployment of Fish Aggregation Devices Alters Environmentally-Based Migratory Behavior of Skipjack Tuna in the Western Pacific Ocean

PubMed Central

Wang, Xuefang; Chen, Yong; Truesdell, Samuel; Xu, Liuxiong; Cao, Jie; Guan, Wenjiang

2014-01-01

Fish aggregation devices (FADs) have been used extensively in the tuna purse seine fishery since the 1980s. This long-term modification of natural habitat has generated discussions as to whether FADs impact movement patterns of tuna species. We examined this question using data collected from the skipjack tuna (Katsuwonus pelamis) fishery. We used the longitudinal gravitational center of catch (G) to examine temporal variability in skipjack movement in the Western and Central Pacific Ocean, and related this to El Niño Southern Oscillation (ENSO) events. We found that in most cases G for free-swimming school sets changed with the onset of ENSO events, while G for floating-object-associated school sets remained relatively constant. This suggests that skipjack exhibit distinguishable behavioral strategies in response to ENSO events: they either react by moving long distances or they associate with floating objects. There has been no previous attempt to evaluate the interaction between FADs and the environmentally-determined movement of skipjack; this study shows evidence of an interaction, which should be considered when managing skipjack populations. PMID:24849561

Adaptability of free-floating green tide algae in the Yellow Sea to variable temperature and light intensity.

PubMed

Cui, Jianjun; Zhang, Jianheng; Huo, Yuanzi; Zhou, Lingjie; Wu, Qing; Chen, Liping; Yu, Kefeng; He, Peimin

2015-12-30

In this study, the influence of temperature and light intensity on the growth of seedlings and adults of four species of green tide algae (Ulvaprolifera, Ulvacompressa, Ulva flexuosa and Ulvalinza) from the Yellow Sea was evaluated. The results indicated that the specific growth rate (SGR) of seedlings was much higher than that of adults for the four species. The adaptability of U. prolifera is much wider: Adult daily SGRs were the highest among the four species at 15-20 °C with 10-600 μmol · m(-2) · s(-1) and 25-30 °C with 200-600 μmol · m(-2) · s(-1). SGRs were 1.5-3.5 times greater than the other three species at 15-25 °C with 200-600 μmol · m(-2) · s(-1). These results indicate that U. prolifera has better tolerance to high temperature and light intensity than the other three species, which may in part explain why only U. prolifera undergoes large-scale outbreaks and floats to the Qingdao coast while the other three species decline and disappear at the early stage of blooming. Copyright © 2015 Elsevier Ltd. All rights reserved.

Leaky Integrate-and-Fire Neuron Circuit Based on Floating-Gate Integrator

PubMed Central

Kornijcuk, Vladimir; Lim, Hyungkwang; Seok, Jun Yeong; Kim, Guhyun; Kim, Seong Keun; Kim, Inho; Choi, Byung Joon; Jeong, Doo Seok

2016-01-01

The artificial spiking neural network (SNN) is promising and has been brought to the notice of the theoretical neuroscience and neuromorphic engineering research communities. In this light, we propose a new type of artificial spiking neuron based on leaky integrate-and-fire (LIF) behavior. A distinctive feature of the proposed FG-LIF neuron is the use of a floating-gate (FG) integrator rather than a capacitor-based one. The relaxation time of the charge on the FG relies mainly on the tunnel barrier profile, e.g., barrier height and thickness (rather than the area). This opens up the possibility of large-scale integration of neurons. The circuit simulation results offered biologically plausible spiking activity (<100 Hz) with a capacitor of merely 6 fF, which is hosted in an FG metal-oxide-semiconductor field-effect transistor. The FG-LIF neuron also has the advantage of low operation power (<30 pW/spike). Finally, the proposed circuit was subject to possible types of noise, e.g., thermal noise and burst noise. The simulation results indicated remarkable distributional features of interspike intervals that are fitted to Gamma distribution functions, similar to biological neurons in the neocortex. PMID:27242416

Variability in the Composition of Floating Microplastics by Region and in Time

NASA Astrophysics Data System (ADS)

Donohue, J. L.; Pavlekovsky, K.; Collins, T.; Andrady, A. L.; Proskurowski, G. K.; Lavender Law, K. L.

2016-02-01

Floating microplastics have been documented in all the subtropical oceans and in many regional seas, yet their origin and weathering history are largely unknown. To identify potential indicators of sources of microplastic debris and changes in input over time, we analyzed nearly 3,000 plastic particles collected using a surface-towing plankton net between 1991 and 2014, collected in the North Pacific subtropical gyre, in the Mediterranean Sea, and across the western North Atlantic basin including the subtropical gyre and coastal locations near urban areas. For each particle we analyzed particle form, size (longest dimension and 2-D surface area), mass, color characteristics and polymer type. We hypothesize that regional differences in average or median particle mass and size are a relative indicator of age (time of exposure), where accumulation zones that retain particles for long periods of time have statistically smaller fragments compared to regions closer to presumed sources. Differences in particle form (i.e., fragment, pellet, foam, line/fiber, film) might also reflect proximity to sources as well as form-dependent removal mechanisms such as density increase and sinking (Ryan 2015). Finally, changes in particle composition over time in subtropical gyre reservoirs could provide clues about changes in input as well as mechanisms and time scale of removal. Understanding the inputs, reservoirs, and sinks of open ocean microplastics is a necessary first step to evaluating their risks and impacts to marine life. Ryan, P., 2015. Does size and buoyancy affect the long-distance transport of floating debris? Environ. Res. Lett. 10 084019.

Proceedings of the International Workshop on Water Waves and Floating Bodies (16th) Held in Hiroshima, Japan on April 22-25, 2001

DTIC Science & Technology

2001-04-25

design. The method should be easy to handle and should not be time consuming. In this aspect, Takagi and Kohara [2000] proposed an application of the...of a Very Large Floating Structure, Proc. of 14th Int. WWWFB, Port Huron, 1999, pp. 13 7- 14 0 . TAKAGI, K. and KOHARA , K. :Application of the Ray

From Trash to Treasure: Recycling Scrap Metal into Steel

ERIC Educational Resources Information Center

Cantu, Diana

2011-01-01

Trash is having a global impact not only on land, but at sea--making its way into the ocean and creating large islands of floating debris. One such island is The Great Pacific Trash Patch, which is located in the North Pacific and is made up of floating trash and debris that is spread out in an area as much as one and a half times the size of the…

Numerical computation of spherical harmonics of arbitrary degree and order by extending exponent of floating point numbers

NASA Astrophysics Data System (ADS)

Fukushima, Toshio

2012-04-01

By extending the exponent of floating point numbers with an additional integer as the power index of a large radix, we compute fully normalized associated Legendre functions (ALF) by recursion without underflow problem. The new method enables us to evaluate ALFs of extremely high degree as 232 = 4,294,967,296, which corresponds to around 1 cm resolution on the Earth's surface. By limiting the application of exponent extension to a few working variables in the recursion, choosing a suitable large power of 2 as the radix, and embedding the contents of the basic arithmetic procedure of floating point numbers with the exponent extension directly in the program computing the recurrence formulas, we achieve the evaluation of ALFs in the double-precision environment at the cost of around 10% increase in computational time per single ALF. This formulation realizes meaningful execution of the spherical harmonic synthesis and/or analysis of arbitrary degree and order.

Hiding and feeding in floating seaweed: Floating seaweed clumps as possible refuges or feeding grounds for fishes

NASA Astrophysics Data System (ADS)

Vandendriessche, Sofie; Messiaen, Marlies; O'Flynn, Sarah; Vincx, Magda; Degraer, Steven

2007-02-01

Floating seaweed is considered to be an important habitat for juvenile fishes due to the provision of food, shelter, a visual orientation point and passive transport. The importance of the presence of the highly dynamical seaweed clumps from the North Sea to juvenile neustonic fishes was investigated by analysing both neuston samples (without seaweed) and seaweed samples concerning fish community structure, and length-frequency distributions and feeding habits of five associated fish species. While the neustonic fish community was mainly seasonally structured, the seaweed-associated fish community was more complex: the response of the associated fish species to environmental variables was species specific and probably influenced by species interactions, resulting in a large multivariate distance between the samples dominated by Chelon labrosus and the samples dominated by Cyclopterus lumpus, Trachurus trachurus and Ciliata mustela. The results of the stomach analysis confirmed that C. lumpus is a weedpatch specialist that has a close spatial affinity with the seaweed and feeds intensively on the seaweed-associated invertebrate fauna. Similarly, C. mustela juveniles also fed on the seaweed fauna, but in a more opportunistic way. The shape of the size-frequency distribution suggested enhanced growth when associated with floating seaweed. Chelon labrosus and T. trachurus juveniles were generally large in seaweed samples, but large individuals were also encountered in the neuston. The proportion of associated invertebrate fauna in their diet was of minor importance, compared to the proportions in C. lumpus. Individuals of Syngnathus rostellatus mainly fed on planktonic invertebrates but had a discontinuous size-frequency distribution, suggesting that some of the syngnathids were carried with the seaweed upon detachment and stayed associated. Floating seaweeds can therefore be regarded as ephemeral habitats shared between several fish species (mainly juveniles) that use them for different reasons and with varying intensity.

Elimination of fecal coliforms and F-specific RNA coliphage from oysters (Crassostrea virginica) relaid in floating containers.

PubMed

Kator, H; Rhodes, M

2001-06-01

Declining oyster (Crassostrea virginica) production in the Chesapeake Bay has stimulated aquaculture based on floats for off-bottom culture. While advantages of off-bottom culture are significant, the increased use of floating containers raises public health and microbiological concerns, because oysters in floats may be more susceptible to fecal contamination from storm runoff compared to those cultured on-bottom. We conducted four commercial-scale studies with market-size oysters naturally contaminated with fecal coliforms (FC) and a candidate viral indicator, F-specific RNA (FRNA) coliphage. To facilitate sampling and to test for location effects, 12 replicate subsamples, each consisting of 15 to 20 randomly selected oysters in plastic mesh bags, were placed at four characteristic locations within a 0.6- by 3.0-m "Taylor" float, and the remaining oysters were added to a depth not exceeding 15.2 cm. The float containing approximately 3,000 oysters was relaid in the York River, Virginia, for 14 days. During relay, increases in shellfish FC densities followed rain events such that final mean levels exceeded initial levels or did not meet an arbitrary product end point of 50 FC/100 ml. FRNA coliphage densities decreased to undetectable levels within 14 days (16 to 28 degrees C) in all but the last experiment, when temperatures fell between 12 and 16 degrees C. Friedman (nonparametric analysis of variance) tests performed on FC/Escherichia coli and FRNA densities indicated no differences in counts as a function of location within the float. The public health consequences of these observations are discussed, and future research and educational needs are identified.

An innovative experimental setup for Large Scale Particle Image Velocimetry measurements in riverine environments

NASA Astrophysics Data System (ADS)

Tauro, Flavia; Olivieri, Giorgio; Porfiri, Maurizio; Grimaldi, Salvatore

2014-05-01

Large Scale Particle Image Velocimetry (LSPIV) is a powerful methodology to nonintrusively monitor surface flows. Its use has been beneficial to the development of rating curves in riverine environments and to map geomorphic features in natural waterways. Typical LSPIV experimental setups rely on the use of mast-mounted cameras for the acquisition of natural stream reaches. Such cameras are installed on stream banks and are angled with respect to the water surface to capture large scale fields of view. Despite its promise and the simplicity of the setup, the practical implementation of LSPIV is affected by several challenges, including the acquisition of ground reference points for image calibration and time-consuming and highly user-assisted procedures to orthorectify images. In this work, we perform LSPIV studies on stream sections in the Aniene and Tiber basins, Italy. To alleviate the limitations of traditional LSPIV implementations, we propose an improved video acquisition setup comprising a telescopic, an inexpensive GoPro Hero 3 video camera, and a system of two lasers. The setup allows for maintaining the camera axis perpendicular to the water surface, thus mitigating uncertainties related to image orthorectification. Further, the mast encases a laser system for remote image calibration, thus allowing for nonintrusively calibrating videos without acquiring ground reference points. We conduct measurements on two different water bodies to outline the performance of the methodology in case of varying flow regimes, illumination conditions, and distribution of surface tracers. Specifically, the Aniene river is characterized by high surface flow velocity, the presence of abundant, homogeneously distributed ripples and water reflections, and a meagre number of buoyant tracers. On the other hand, the Tiber river presents lower surface flows, isolated reflections, and several floating objects. Videos are processed through image-based analyses to correct for lens distortions and analyzed with a commercially available PIV software. Surface flow velocity estimates are compared to supervised measurements performed by visually tracking objects floating on the stream surface and to rating curves developed by the Ufficio Idrografico e Mareografico (UIM) at Regione Lazio, Italy. Experimental findings demonstrate that the presence of tracers is crucial for surface flow velocity estimates. Further, considering surface ripples and patterns may lead to underestimations in LSPIV analyses.

Biogrid--a microfluidic device for large-scale enzyme-free dissociation of stem cell aggregates.

PubMed

Wallman, Lars; Åkesson, Elisabet; Ceric, Dario; Andersson, Per Henrik; Day, Kelly; Hovatta, Outi; Falci, Scott; Laurell, Thomas; Sundström, Erik

2011-10-07

Culturing stem cells as free-floating aggregates in suspension facilitates large-scale production of cells in closed systems, for clinical use. To comply with GMP standards, the use of substances such as proteolytic enzymes should be avoided. Instead of enzymatic dissociation, the growing cell aggregates may be mechanically cut at passage, but available methods are not compatible with large-scale cell production and hence translation into the clinic becomes a severe bottle-neck. We have developed the Biogrid device, which consists of an array of micrometerscale knife edges, micro-fabricated in silicon, and a manifold in which the microgrid is placed across the central fluid channel. By connecting one side of the Biogrid to a syringe or a pump and the other side to the cell culture, the culture medium with suspended cell aggregates can be aspirated, forcing the aggregates through the microgrid, and ejected back to the cell culture container. Large aggregates are thereby dissociated into smaller fragments while small aggregates pass through the microgrid unaffected. As proof-of-concept, we demonstrate that the Biogrid device can be successfully used for repeated passage of human neural stem/progenitor cells cultured as so-called neurospheres, as well as for passage of suspension cultures of human embryonic stem cells. We also show that human neural stem/progenitor cells tolerate transient pressure changes far exceeding those that will occur in a fluidic system incorporating the Biogrid microgrids. Thus, by using the Biogrid device it is possible to mechanically passage large quantities of cells in suspension cultures in closed fluidic systems, without the use of proteolytic enzymes.

Fluid mechanics and mass transfer in melt crystal growth: Analysis of the floating zone and vertical Bridgman processes

NASA Technical Reports Server (NTRS)

Brown, R. A.

1986-01-01

This research program focuses on analysis of the transport mechanisms in solidification processes, especially one of interest to the Microgravity Sciences and Applications Program of NASA. Research during the last year has focused on analysis of the dynamics of the floating zone process for growth of small-scale crystals, on studies of the effect of applied magnetic fields on convection and solute segregation in directional solidification, and on the dynamics of microscopic cell formation in two-dimensional solidification of binary alloys. Significant findings are given.

Floating-to-Fixed-Point Conversion for Digital Signal Processors

NASA Astrophysics Data System (ADS)

Menard, Daniel; Chillet, Daniel; Sentieys, Olivier

2006-12-01

Digital signal processing applications are specified with floating-point data types but they are usually implemented in embedded systems with fixed-point arithmetic to minimise cost and power consumption. Thus, methodologies which establish automatically the fixed-point specification are required to reduce the application time-to-market. In this paper, a new methodology for the floating-to-fixed point conversion is proposed for software implementations. The aim of our approach is to determine the fixed-point specification which minimises the code execution time for a given accuracy constraint. Compared to previous methodologies, our approach takes into account the DSP architecture to optimise the fixed-point formats and the floating-to-fixed-point conversion process is coupled with the code generation process. The fixed-point data types and the position of the scaling operations are optimised to reduce the code execution time. To evaluate the fixed-point computation accuracy, an analytical approach is used to reduce the optimisation time compared to the existing methods based on simulation. The methodology stages are described and several experiment results are presented to underline the efficiency of this approach.

Hardware math for the 6502 microprocessor

NASA Technical Reports Server (NTRS)

Kissel, R.; Currie, J.

1985-01-01

A floating-point arithmetic unit is described which is being used in the Ground Facility of Large Space Structures Control Verification (GF/LSSCV). The experiment uses two complete inertial measurement units and a set of three gimbal torquers in a closed loop to control the structural vibrations in a flexible test article (beam). A 6502 (8-bit) microprocessor controls four AMD 9511A floating-point arithmetic units to do all the computation in 20 milliseconds.

Ships as future floating farm systems?

PubMed

Moustafa, Khaled

2018-04-03

Environmental and agriculture challenges such as severe drought, desertification, sprawling cities and shrinking arable lands in large regions in the world compel us to think about alternative and sustainable farming systems. Ongoing projects to build floating cities in the sea suggest that building specific ships for farming purposes (as farming ships or farming boats) would also be attainable to introduce new farming surfaces and boost food production worldwide to cope with food insecurity issues.

Between soap bubbles and vesicles: The dynamics of freely floating smectic bubbles

NASA Astrophysics Data System (ADS)

Stannarius, Ralf; May, Kathrin; Harth, Kirsten; Trittel, Torsten

2013-03-01

The dynamics of droplets and bubbles, particularly on microscopic scales, are of considerable importance in biological, environmental, and technical contexts. We introduce freely floating bubbles of smectic liquid crystals and report their unique dynamic properties. Smectic bubbles can be used as simple models for dynamic studies of fluid membranes. In equilibrium, they form minimal surfaces like soap films. However, shape transformations of closed smectic membranes that change the surface area involve the formation and motion of molecular layer dislocations. These processes are slow compared to the capillary wave dynamics, therefore the effective surface tension is zero like in vesicles. Freely floating smectic bubbles are prepared from collapsing catenoid films and their dynamics is studied with optical high-speed imaging. Experiments are performed under normal gravity and in microgravity during parabolic flights. Supported by DLR within grant OASIS-Co.

Design of crossed-mirror array to form floating 3D LED signs

NASA Astrophysics Data System (ADS)

Yamamoto, Hirotsugu; Bando, Hiroki; Kujime, Ryousuke; Suyama, Shiro

2012-03-01

3D representation of digital signage improves its significance and rapid notification of important points. Our goal is to realize floating 3D LED signs. The problem is there is no sufficient device to form floating 3D images from LEDs. LED lamp size is around 1 cm including wiring and substrates. Such large pitch increases display size and sometimes spoils image quality. The purpose of this paper is to develop optical device to meet the three requirements and to demonstrate floating 3D arrays of LEDs. We analytically investigate image formation by a crossed mirror structure with aerial aperture, called CMA (crossed-mirror array). CMA contains dihedral corner reflectors at each aperture. After double reflection, light rays emitted from an LED will converge into the corresponding image point. We have fabricated CMA for 3D array of LEDs. One CMA unit contains 20 x 20 apertures that are located diagonally. Floating image of LEDs was formed in wide range of incident angle. The image size of focused beam agreed to the apparent aperture size. When LEDs were located three-dimensionally (LEDs in three depths), the focused distances were the same as the distance between the real LED and the CMA.

Newton's Third Law on a Scale Balance

ERIC Educational Resources Information Center

Nopparatjamjomras, Suchai; Panijpan, Bhinyo; Huntula, Jiradawan

2009-01-01

We propose a series of experiments involving balance readings of an object naturally floating or forced to be partially or fully immersed in water contained in a beaker sitting on an electronic scale balance. Students were asked to predict, observe and explain each case. The teacher facilitated the learning by asking probing questions, giving…

Experimental Comparison of Dynamic Responses of a Tension Moored Floating Wind Turbine Platform with and without Spring Dampers

NASA Astrophysics Data System (ADS)

Wright, C.; O'Sullivan, K.; Murphy, J.; Pakrashi, V.

2015-07-01

The offshore wind industry is rapidly maturing and is now expanding to more extreme environments in deeper water and farther from shore. To date fixed foundation types (i.e. monopoles, jackets) have been primarily used but become uneconomical in water depths greater than 50m. Floating foundations have more complex dynamics but at the moment no design has reached commercialization, although a number of devices are being tested at prototype stage. The development of concepts is carried out through physical model testing of scaled devices such that to better understand the dynamics of the system and validate numerical models. This paper investigates the testing of a scale model of a tension moored wind turbine at two different scales and in the presence and absence of a spring damper controlling its dynamic response. The models were tested under combined wave and wind thrust loading conditions. The analysis compares the motions of the platform at different scales and structural conditions through RAO, testing a mooring spring damper for load reductions.

Physical and Biological Drivers of Biogeochemical Tracers Within the Seasonal Sea Ice Zone of the Southern Ocean From Profiling Floats

NASA Astrophysics Data System (ADS)

Briggs, Ellen M.; Martz, Todd R.; Talley, Lynne D.; Mazloff, Matthew R.; Johnson, Kenneth S.

2018-02-01

Here we present initial findings from nine profiling floats equipped with pH, O2, NO3-, and other biogeochemical sensors that were deployed in the seasonal ice zone (SIZ) of the Southern Ocean in 2014 and 2015 through the Southern Ocean Carbon and Climate Observations and Modelling (SOCCOM) project. A large springtime phytoplankton bloom was observed that coincided with sea ice melt for all nine floats. We argue this bloom results from a shoaling of the mixed layer depth, increased vertical stability, and enhanced nutrient and light availability as the sea ice melts. This interpretation is supported by the absence of a springtime bloom when one of the floats left the SIZ in the second year of observations. During the sea ice covered period, net heterotrophic conditions were observed. The rate of uptake of O2 and release of dissolved inorganic carbon (derived from pH and estimated total alkalinity) and NO3- is reminiscent of biological respiration and is nearly Redfieldian for the nine floats. A simple model of mixed layer physics was developed to separate the physical and biological components of the signal in pH and O2 over one annual cycle for a float in the Ross Sea SIZ. The resulting annual net community production suggests that seasonal respiration during the ice covered period of the year nearly balances the production in the euphotic layer of up to 5 mol C m-2 during the ice free period leading to a net of near zero carbon exported to depth for this one float.

Tidal bending of ice shelves as a mechanism for large-scale temporal variations in ice flow

NASA Astrophysics Data System (ADS)

Rosier, Sebastian H. R.; Hilmar Gudmundsson, G.

2018-05-01

GPS measurements reveal strong modulation of horizontal ice shelf and ice stream flow at a variety of tidal frequencies, most notably a fortnightly (Msf) frequency not present in the vertical tides themselves. Current theories largely fail to explain the strength and prevalence of this signal over floating ice shelves. We show how well-known non-linear aspects of ice rheology can give rise to widespread, long-periodic tidal modulation in ice shelf flow, generated within ice shelves themselves through tidal flexure acting at diurnal and semidiurnal frequencies. Using full-Stokes viscoelastic modelling, we show that inclusion of tidal bending within the model accounts for much of the observed tidal modulation of ice shelf flow. Furthermore, our model shows that, in the absence of vertical tidal forcing, the mean flow of the ice shelf is reduced by almost 30 % for the geometry that we consider.

Distribution and trajectories of floating and benthic marine macrolitter in the south-eastern North Sea.

PubMed

Gutow, Lars; Ricker, Marcel; Holstein, Jan M; Dannheim, Jennifer; Stanev, Emil V; Wolff, Jörg-Olaf

2018-06-01

In coastal waters the identification of sources, trajectories and deposition sites of marine litter is often hampered by the complex oceanography of shallow shelf seas. We conducted a multi-annual survey on litter at the sea surface and on the seafloor in the south-eastern North Sea. Bottom trawling was identified as a major source of marine litter. Oceanographic modelling revealed that the distribution of floating litter in the North Sea is largely determined by the site of origin of floating objects whereas the trajectories are strongly influenced by wind drag. Methods adopted from species distribution modelling indicated that resuspension of benthic litter and near-bottom transport processes strongly influence the distribution of litter on the seafloor. Major sink regions for floating marine litter were identified at the west coast of Denmark and in the Skagerrak. Our results may support the development of strategies to reduce the pollution of the North Sea. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fluid Surface Deformation by Objects in the Cheerios Effect

NASA Astrophysics Data System (ADS)

Nguyen, Khoi; Miller, Michael; Mandre, Shreyas; Mandre Lab Team

2012-11-01

Small objects floating on a fluid/air interface deform of the surface depending on material surface properties, density, and geometry. These objects attract each other through capillary interactions, a phenomenon dubbed the ``cheerios effect.'' The attractive force and torque exerted on these objects by the interface can be estimated if the meniscus deformation is known. In addition, the floating objects can also rotate due to such an interaction. We present a series of experiments focused on visualizing the the motions of the floating objects and the deformation of the interface. The experiments involve thin laser-cut acrylic pieces attracting each other on water in a large glass petri dish and a camera set-up to capture the process. Furthermore, optical distortion of a grid pattern is used to visualize the water surface deformation near the edge of the objects. This study of the deformation of the water surface around a floating object, of the attractive/repulsive forces, and of post-contact rotational dynamics are potentially instrumental in the study of colloidal self-assembly.

Computation of the inviscid supersonic flow about cones at large angles of attack by a floating discontinuity approach

NASA Technical Reports Server (NTRS)

Daywitt, J.; Kutler, P.; Anderson, D.

1977-01-01

The technique of floating shock fitting is adapted to the computation of the inviscid flowfield about circular cones in a supersonic free stream at angles of attack that exceed the cone half-angle. The resulting equations are applicable over the complete range of free-stream Mach numbers, angles of attack and cone half-angles for which the bow shock is attached. A finite difference algorithm is used to obtain the solution by an unsteady relaxation approach. The bow shock, embedded cross-flow shock, and vortical singularity in the leeward symmetry plane are treated as floating discontinuities in a fixed computational mesh. Where possible, the flowfield is partitioned into windward, shoulder, and leeward regions with each region computed separately to achieve maximum computational efficiency. An alternative shock fitting technique which treats the bow shock as a computational boundary is developed and compared with the floating-fitting approach. Several surface boundary condition schemes are also analyzed.

Is a 4-bit synaptic weight resolution enough? - constraints on enabling spike-timing dependent plasticity in neuromorphic hardware.

PubMed

Pfeil, Thomas; Potjans, Tobias C; Schrader, Sven; Potjans, Wiebke; Schemmel, Johannes; Diesmann, Markus; Meier, Karlheinz

2012-01-01

Large-scale neuromorphic hardware systems typically bear the trade-off between detail level and required chip resources. Especially when implementing spike-timing dependent plasticity, reduction in resources leads to limitations as compared to floating point precision. By design, a natural modification that saves resources would be reducing synaptic weight resolution. In this study, we give an estimate for the impact of synaptic weight discretization on different levels, ranging from random walks of individual weights to computer simulations of spiking neural networks. The FACETS wafer-scale hardware system offers a 4-bit resolution of synaptic weights, which is shown to be sufficient within the scope of our network benchmark. Our findings indicate that increasing the resolution may not even be useful in light of further restrictions of customized mixed-signal synapses. In addition, variations due to production imperfections are investigated and shown to be uncritical in the context of the presented study. Our results represent a general framework for setting up and configuring hardware-constrained synapses. We suggest how weight discretization could be considered for other backends dedicated to large-scale simulations. Thus, our proposition of a good hardware verification practice may rise synergy effects between hardware developers and neuroscientists.

Is a 4-Bit Synaptic Weight Resolution Enough? – Constraints on Enabling Spike-Timing Dependent Plasticity in Neuromorphic Hardware

PubMed Central

Pfeil, Thomas; Potjans, Tobias C.; Schrader, Sven; Potjans, Wiebke; Schemmel, Johannes; Diesmann, Markus; Meier, Karlheinz

2012-01-01

Large-scale neuromorphic hardware systems typically bear the trade-off between detail level and required chip resources. Especially when implementing spike-timing dependent plasticity, reduction in resources leads to limitations as compared to floating point precision. By design, a natural modification that saves resources would be reducing synaptic weight resolution. In this study, we give an estimate for the impact of synaptic weight discretization on different levels, ranging from random walks of individual weights to computer simulations of spiking neural networks. The FACETS wafer-scale hardware system offers a 4-bit resolution of synaptic weights, which is shown to be sufficient within the scope of our network benchmark. Our findings indicate that increasing the resolution may not even be useful in light of further restrictions of customized mixed-signal synapses. In addition, variations due to production imperfections are investigated and shown to be uncritical in the context of the presented study. Our results represent a general framework for setting up and configuring hardware-constrained synapses. We suggest how weight discretization could be considered for other backends dedicated to large-scale simulations. Thus, our proposition of a good hardware verification practice may rise synergy effects between hardware developers and neuroscientists. PMID:22822388

Floating vs flying: A propulsion energy comparison

NASA Technical Reports Server (NTRS)

Marbury, F.

1975-01-01

Floating craft are compared to those that fly. Drag/weight for floaters is shown to be proportional to v squared/L, while for flyers it is independent of size and speed. The transportation market will therefore assign airships to lower speeds than airplanes, and will favor large airship sizes. Drag of an airship is shown to be only 11 percent of submarine drag at equal displacement and speed, raising the possibility that airships can compete with some types of ships.

Floating gate transistors as biosensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Frisbie, C. Daniel

2016-11-01

Electrolyte gated transistors (EGTs) are a sub-class of thin film transistors that are extremely promising for biological sensing applications. These devices employ a solid electrolyte as the gate insulator; the very large capacitance of the electrolyte results in low voltage operation and high transconductance or gain. This talk will describe the fabrication of floating gate EGTs and their use as ricin sensors. The critical performance metrics for EGTs compared with other types of TFTs will also be reviewed.

Phyllosphere bacterial community of floating macrophytes in paddy soil environments as revealed by illumina high-throughput sequencing.

PubMed

Xie, Wan-Ying; Su, Jian-Qiang; Zhu, Yong-Guan

2015-01-01

The phyllosphere of floating macrophytes in paddy soil ecosystems, a unique habitat, may support large microbial communities but remains largely unknown. We took Wolffia australiana as a representative floating plant and investigated its phyllosphere bacterial community and the underlying driving forces of community modulation in paddy soil ecosystems using Illumina HiSeq 2000 platform-based 16S rRNA gene sequence analysis. The results showed that the phyllosphere of W. australiana harbored considerably rich communities of bacteria, with Proteobacteria and Bacteroidetes as the predominant phyla. The core microbiome in the phyllosphere contained genera such as Acidovorax, Asticcacaulis, Methylibium, and Methylophilus. Complexity of the phyllosphere bacterial communities in terms of class number and α-diversity was reduced compared to those in corresponding water and soil. Furthermore, the bacterial communities exhibited structures significantly different from those in water and soil. These findings and the following redundancy analysis (RDA) suggest that species sorting played an important role in the recruitment of bacterial species in the phyllosphere. The compositional structures of the phyllosphere bacterial communities were modulated predominantly by water physicochemical properties, while the initial soil bacterial communities had limited impact. Taken together, the findings from this study reveal the diversity and uniqueness of the phyllosphere bacterial communities associated with the floating macrophytes in paddy soil environments. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Phyllosphere Bacterial Community of Floating Macrophytes in Paddy Soil Environments as Revealed by Illumina High-Throughput Sequencing

PubMed Central

Xie, Wan-Ying

2014-01-01

The phyllosphere of floating macrophytes in paddy soil ecosystems, a unique habitat, may support large microbial communities but remains largely unknown. We took Wolffia australiana as a representative floating plant and investigated its phyllosphere bacterial community and the underlying driving forces of community modulation in paddy soil ecosystems using Illumina HiSeq 2000 platform-based 16S rRNA gene sequence analysis. The results showed that the phyllosphere of W. australiana harbored considerably rich communities of bacteria, with Proteobacteria and Bacteroidetes as the predominant phyla. The core microbiome in the phyllosphere contained genera such as Acidovorax, Asticcacaulis, Methylibium, and Methylophilus. Complexity of the phyllosphere bacterial communities in terms of class number and α-diversity was reduced compared to those in corresponding water and soil. Furthermore, the bacterial communities exhibited structures significantly different from those in water and soil. These findings and the following redundancy analysis (RDA) suggest that species sorting played an important role in the recruitment of bacterial species in the phyllosphere. The compositional structures of the phyllosphere bacterial communities were modulated predominantly by water physicochemical properties, while the initial soil bacterial communities had limited impact. Taken together, the findings from this study reveal the diversity and uniqueness of the phyllosphere bacterial communities associated with the floating macrophytes in paddy soil environments. PMID:25362067

Efficient electronic structure theory via hierarchical scale-adaptive coupled-cluster formalism: I. Theory and computational complexity analysis

NASA Astrophysics Data System (ADS)

Lyakh, Dmitry I.

2018-03-01

A novel reduced-scaling, general-order coupled-cluster approach is formulated by exploiting hierarchical representations of many-body tensors, combined with the recently suggested formalism of scale-adaptive tensor algebra. Inspired by the hierarchical techniques from the renormalisation group approach, H/H2-matrix algebra and fast multipole method, the computational scaling reduction in our formalism is achieved via coarsening of quantum many-body interactions at larger interaction scales, thus imposing a hierarchical structure on many-body tensors of coupled-cluster theory. In our approach, the interaction scale can be defined on any appropriate Euclidean domain (spatial domain, momentum-space domain, energy domain, etc.). We show that the hierarchically resolved many-body tensors can reduce the storage requirements to O(N), where N is the number of simulated quantum particles. Subsequently, we prove that any connected many-body diagram consisting of a finite number of arbitrary-order tensors, e.g. an arbitrary coupled-cluster diagram, can be evaluated in O(NlogN) floating-point operations. On top of that, we suggest an additional approximation to further reduce the computational complexity of higher order coupled-cluster equations, i.e. equations involving higher than double excitations, which otherwise would introduce a large prefactor into formal O(NlogN) scaling.

Downscaling ocean conditions with application to the Gulf of Maine, Scotian Shelf and adjacent deep ocean

NASA Astrophysics Data System (ADS)

Katavouta, Anna; Thompson, Keith R.

2016-08-01

The overall goal is to downscale ocean conditions predicted by an existing global prediction system and evaluate the results using observations from the Gulf of Maine, Scotian Shelf and adjacent deep ocean. The first step is to develop a one-way nested regional model and evaluate its predictions using observations from multiple sources including satellite-borne sensors of surface temperature and sea level, CTDs, Argo floats and moored current meters. It is shown that the regional model predicts more realistic fields than the global system on the shelf because it has higher resolution and includes tides that are absent from the global system. However, in deep water the regional model misplaces deep ocean eddies and meanders associated with the Gulf Stream. This is not because the regional model's dynamics are flawed but rather is the result of internally generated variability in deep water that leads to decoupling of the regional model from the global system. To overcome this problem, the next step is to spectrally nudge the regional model to the large scales (length scales > 90 km) of the global system. It is shown this leads to more realistic predictions off the shelf. Wavenumber spectra show that even though spectral nudging constrains the large scales, it does not suppress the variability on small scales; on the contrary, it favours the formation of eddies with length scales below the cutoff wavelength of the spectral nudging.

Ship-Based Nuclear Energy Systems for Accelerating Developing World Socioeconomic Advance

NASA Astrophysics Data System (ADS)

Petroski, Robert; Wood, Lowell

2014-07-01

Technological, economic, and policy aspects of supplying energy to newly industrializing and developing countries using ship-deployed nuclear energy systems are described. The approach analyzed comprises nuclear installations of up to gigawatt scale deployed within currently mass-produced large ship hulls which are capable of flexibly supplying energy for electricity, water desalination and district heating-&-cooling with low latencies and minimized shoreside capital expenditures. Nuclear energy is uniquely suited for mobile deployment due to its combination of extraordinary energy density and high power density, which enable enormous supplies of energy to be deployed at extremely low marginal costs. Nuclear installations on ships also confer technological advantages by essentially eliminating risk from earthquakes, tsunamis, and floods; taking advantage of assured access to an effectively unlimited amount of cooling water, and involving minimal onshore preparations and commitments. Instances of floating nuclear power stations that have been proposed in the past, some of which are currently being pursued, have generally been based on conventional LWR technology, moreover without flexibility or completeness of power output options. We consider nuclear technology options for their applicability to the unique opportunities and challenges of a marine environment, with special attention given to low-pressure, high thermal margin systems with continuous and assured afterheat dissipation into the ambient seawater. Such systems appear promising for offering an exceptionally high degree of safety while using a maximally simple set of components. We furthermore consider systems tailored to Developing World contexts, which satisfy societal requirements beyond electrification, e.g., flexible sourcing of potable water and HVAC services, servicing time-varying user requirements, and compatibility with the full spectrum of local renewable energy supplies, specifically including those having intermittency characteristics. Consideration is directed to the relative economics of ship-based and land-based nuclear power stations, and the costs of undersea transmission lines and suitable moorings are discussed, as well as station-maintenance expenses. Potential cost savings from reduced seismic engineering, serialized production, and reduction/elimination of site-specific engineering are determined to be likely to enable large floating nuclear energy systems to be deployed at both significantly lower cost and with lower financial risk than comparable land-based systems. Such plants thus appear to be a compelling option for agilely supplying flexible energy-flows to developing regions, especially as they allow major components of the overhead costs and time-delays of large-scale energy systems to be avoided. Finally, the critical set of issues related to appropriately regulating and insuring floating nuclear power plants designed for export is examined. Approaches to ensuring adequate safety and environmental stewardship while properly allocating risks between system owners/operators and host countries of floating nuclear energy systems are discussed, along with possible pathways toward implementation. Robustness of exemplary nuclear energy systems from all forms of misuse, including materials diversion, is noted, thus ensuring suitability for complications-free, non-discriminatory global deployments. Availability of abundant, low-cost nuclear energy which can flexibly satisfy the full spectrum of energy demands of the economies of developing countries will inevitably result in significantly earlier and more environmentally-sound energy intensification of societies enjoying such advantages. This will help spur autocatalytic gains in human well-being and economic development rates similar to those seen in the developed world during the last two-thirds of a century, while avoiding some of the undesirable sideeffects often associated with those gains. Quantitative estimates of these considerations are offered.

A preliminary study of the feasibility of detecting the floating macrophytes by means of digital processing of MSS/LANDSAT data

NASA Technical Reports Server (NTRS)

Valeriano, D. D. (Principal Investigator)

1984-01-01

The feasibility of mapping the floating macrophytes (mostly water hyacinth: (Eichornia crassipes) in the Salto Grande reservoir in Americana, SP, by means of digital processing of MSS/LANDSAT data is described. The area occupied by the macrophytes was extracted by exclusion after the merging of two thematic masks representing the area of vegetation free water surface. One of the masks was obtained from a date when the vegetal cover is insignificant, while the other represents a large infestation episode. The utilization of digital processing of MSS/LANDSAT data techniques for the documentation of macrophytes infestation is feasible only when the phenomenon occurs in large areas.

Floating zone growth of α-Na 0.90MnO 2 single crystals

DOE PAGES

Dally, Rebecca; Clement, Raphaele J.; Chisnell, Robin; ...

2016-12-03

Here, single crystal growth of α-Na xMnO 2 (x=0.90) is reported via the floating zone technique. The conditions required for stable growth and intergrowth-free crystals are described along with the results of trials under alternate growth atmospheres. Chemical and structural characterizations of the resulting α-Na 0.90MnO 2 crystals are performed using ICP-AES NMR, XANES, XPS, and neutron diffraction measurements. As a layered transition metal oxide with large ionic mobility and strong correlation effects, α-Na xMnO 2 is of interest to many communities, and the implications of large volume, high purity, single crystal growth are discussed.

Balancing Riparian Management and River Recreation: Methods and Applications for Exploring Floater Behavior and Their Interaction with Large Wood

NASA Astrophysics Data System (ADS)

Biedenweg, Kelly; Akyuz, Kate; Skeele, Rebecca

2012-08-01

River managers are tasked with meeting both ecological and human needs. In the Puget Sound lowland, riparian management often includes placing or allowing the presence of large wood to stabilize riverbanks and enhance salmon habitat. Although this practice benefits humans by protecting infrastructure and natural resources, it is unclear how such practices interact with an additional human interest, recreation. Furthermore, we were unable to find studies that describe how an agency can go about researching the interaction between recreation and large wood management practices. This study tested methods for describing and estimating the number of river floaters, where they float in relationship to river projects, the risks they take while floating, and their perceptions of large wood in the river. Selecting a high-use suburban river in Washington State, we used riverside observations, interviews, and an infrared counter to gather data in the summer of 2010. Statistical analyses provided general characteristics of users, trends in engaging in risky behaviors, and estimates of use for the entire season and on the busiest day. Data mapping with GIS presented the density of use along the river and frequency of use of specific float routes. Finally, qualitative analysis of interviews clarified floaters' perspectives of large wood. To address the multiple mandates of river managers, it is important to understand recreation users, the factors that could be putting them at risk, and how the actual users perceive large wood in the river. This study demonstrates methods for scientifically gathering such information and applying it when making riparian management decisions.

Floating Offshore Wind in Hawaii: Potential for Jobs and Economic Impacts from Three Future Scenarios

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

Jimenez, Tony; Keyser, David; Tegen, Suzanne

Construction of the first offshore wind power plant in the United States began in 2015, off the coast of Rhode Island, using fixed platform structures that are appropriate for shallow seafloors, like those located off the East Coast and mid-Atlantic. However, floating platforms, which have yet to be deployed commercially, will likely need to be anchored to the deeper seafloor if deployed in Hawaiian waters. To analyze the employment and economic potential for floating offshore wind off Hawaii's coasts, the Bureau of Ocean Energy Management commissioned the National Renewable Energy Laboratory (NREL) to analyze two hypothetical deployment scenarios for Hawaii:more » 400 MW of offshore wind by 2050 and 800 MW of offshore wind by 2050. The results of this analysis can be used to better understand the general scale of economic opportunities that could result from offshore wind development.« less

Comparison Between Terrestrial Explosion Crater Morphology in Floating Ice and Europan Chaos

NASA Technical Reports Server (NTRS)

Billings, S. E.; Kattenhorn, S. A.

2003-01-01

Craters created by explosives have been found to serve as valuable analogs to impact craters, within limits. Explosion craters have been created in floating terrestrial ice in experiments related to clearing ice from waterways. Features called chaos occur on the surface of Europa s floating ice shell. Chaos is defined as a region in which the background plains have been disrupted. Common features of chaos include rafted blocks of pre-existing terrain suspended in a matrix of smooth or hummocky material; low surface albedo; and structural control on chaos outline shape by pre-existing lineaments. All published models of chaos formation call on endogenic processes whereby chaos forms through thermal processes. Nonetheless, we note morphological similarities between terrestrial explosion craters and Europan chaos at a range of scales and consider whether some chaos may have formed by impact. We explore these similarities through geologic and morphologic mapping.

The use of Argo for validation and tuning of mixed layer models

NASA Astrophysics Data System (ADS)

Acreman, D. M.; Jeffery, C. D.

We present results from validation and tuning of 1-D ocean mixed layer models using data from Argo floats and data from Ocean Weather Station Papa (145°W, 50°N). Model tests at Ocean Weather Station Papa showed that a bulk model could perform well provided it was tuned correctly. The Large et al. [Large, W.G., McWilliams, J.C., Doney, S.C., 1994. Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterisation. Rev. Geophys. 32 (Novermber), 363-403] K-profile parameterisation (KPP) model also gave a good representation of mixed layer depth provided the vertical resolution was sufficiently high. Model tests using data from a single Argo float indicated a tendency for the KPP model to deepen insufficiently over an annual cycle, whereas the tuned bulk model and general ocean turbulence model (GOTM) gave a better representation of mixed layer depth. The bulk model was then tuned using data from a sample of Argo floats and a set of optimum parameters was found; these optimum parameters were consistent with the tuning at OWS Papa.

General Classification Handbook for Floodplain Vegetation in Large River Systems. Chapter 1 of Book 2, Collection of Environmental Data

DTIC Science & Technology

2004-01-01

chlorophyll content, and the more vigorous the growth , the greater the reflectance. This helps the photointerpreter to better distinguish between plant and...land cover map and the field determinations for each class. Based on the error matrix, the accuracy rate for classifying each map class can be...duck- weed (Lemna, Spirodela, and Wolffia) and other nonrooted- floating aquatics. Because duckweed is free-floating, it can relocate day-to-day

Scalable fabrication of nanostructured devices on flexible substrates using additive driven self-assembly and nanoimprint lithography

NASA Astrophysics Data System (ADS)

Watkins, James

2013-03-01

Roll-to-roll (R2R) technologies provide routes for continuous production of flexible, nanostructured materials and devices with high throughput and low cost. We employ additive-driven self-assembly to produce well-ordered polymer/nanoparticle hybrid materials that can serve as active device layers, we use highly filled nanoparticle/polymer hybrids for applications that require tailored dielectric constant or refractive index, and we employ R2R nanoimprint lithography for device scale patterning. Specific examples include the fabrication of flexible floating gate memory and large area films for optical/EM management. Our newly constructed R2R processing facility includes a custom designed, precision R2R UV-assisted nanoimprint lithography (NIL) system and hybrid nanostructured materials coaters.

New method of extrapolation of the resistance of a model planing boat to full size

NASA Technical Reports Server (NTRS)

Sottorf, W

1942-01-01

The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable.

Sub-glacier ocean properties and mass balance estimates of Petermann Gletscher's floating tongue in Northwestern Greenland

NASA Astrophysics Data System (ADS)

Steffen, K.; Huff, R. D.; Cullen, N.; Rignot, E.; Bauder, A.

2004-12-01

Petermann Gletscher is the largest and most influential outlet glacier in central northern Greenland. Located at 81 N, 60 W, it drains an area of 71,580 km2, with a discharge of 12 cubic km of ice per year into the Arctic Ocean. We finished a third field season in spring 2004 collecting in situ data on local climate, ice velocity, ice thickness profiles and bottom melt rates of the floating ice tongue. In addition, water properties (salinity and temperature profiles) in large, channel-like bottom cavities beneath the floating ice tongue were measured. The melt rates in these "channels" are in excess of 10 m/y and probably responsible for most of the mass loss of the Petermann Gletscher. The ocean measurements will be discussed in comparison with other ocean-profile soundings in the region. The bottom topography of the floating ice tongue has been mapped for some regions using surface-based ground penetrating radar at 25 MHz frequency and NASA aircraft radar profiles. A new map showing these under-ice features will be presented. GPS tidal motion has been measured over one lunar cycle at the flex zone and on the free floating ice tongue. These results will be compared to historic measurements made at the beginning of last century. A "worm-like" sheer feature of 80 m in height and several km in length has been studied using differential GPS readings. The mean velocity of the floating tongue ice is 1.08 km/y in that region, whereas the ice along the margin has a 30%-reduced flow speed, resulting in this strange looking sheer feature. Finally, the mass balance of the floating ice tongue will be discussed based on in situ measurements, aircraft profiles, satellite data, and model approximations.

Dynamic response mitigation of floating wind turbine platforms using tuned liquid column dampers.

PubMed

Jaksic, V; Wright, C S; Murphy, J; Afeef, C; Ali, S F; Mandic, D P; Pakrashi, V

2015-02-28

In this paper, we experimentally study and compare the effects of three combinations of multiple tuned liquid column dampers (MTLCDs) on the dynamic performance of a model floating tension-leg platform (TLP) structure in a wave basin. The structural stability and safety of the floating structure during operation and maintenance is of concern for the performance of a renewable energy device that it might be supporting. The dynamic responses of the structure should thus be limited for these renewable energy devices to perform as intended. This issue is particularly important during the operation of a TLP in extreme weather conditions. Tuned liquid column dampers (TLCDs) can use the power of sloshing water to reduce surge motions of a floating TLP exposed to wind and waves. This paper demonstrates the potential of MTLCDs in reducing dynamic responses of a scaled TLP model through an experimental study. The potential of using output-only statistical markers for monitoring changes in structural conditions is also investigated through the application of a delay vector variance (DVV) marker for different conditions of control for the experiments. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Floating Ice-Algal Aggregates below Melting Arctic Sea Ice

PubMed Central

Assmy, Philipp; Ehn, Jens K.; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A.; Hudson, Stephen R.; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H. H.; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

2013-01-01

During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year. PMID:24204642

Floating ice-algal aggregates below melting arctic sea ice.

PubMed

Assmy, Philipp; Ehn, Jens K; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A; Hudson, Stephen R; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H H; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

2013-01-01

During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year.

The Petermann Glacier Experiment, NW Greenland

NASA Astrophysics Data System (ADS)

Mix, A. C.; Jakobsson, M.; Andrews, J. T.; Jennings, A. E.; Mayer, L. A.; Marcott, S. A.; Muenchow, A.; Stoner, J. S.; Andresen, C. S.; Nicholls, K. W.; Anderson, S. T.; Brook, E.; Ceperley, E. G.; Cheseby, M.; Clark, J.; Dalerum, F.; Dyke, L. M.; Einarsson, D.; Eriksson, B.; Frojd, C.; Glueder, A.; Hedman, U.; Heirman, K.; Heuzé, C.; Hogan, K.; Holden, R.; Holm, C.; Jerram, K.; Krutzfeldt, J.; Nicolas, L.; Par, L.; Lomac-MacNair, K.; Madlener, S.; McKay, J. L.; Meijer, T.; Meiton, A.; Brian, M.; Mohammed, R.; Molin, M.; Moser, C.; Normark, E.; Padman, J.; Pecnerova, P.; Reilly, B.; Reusche, M.; Ross, A.; Stranne, C.; Trinhammer, P.; Walczak, M. H.; Walczak, P.; Washam, P.; Karasti, M.; Anker, P.

2016-12-01

The Petermann Glacier Experiment is a comprehensive study on land, ocean, and ice in Northwest Greenland, staged from Swedish Icebreaker Oden in 2015 as a collaboration between the US, Sweden, UK, and Denmark. This talk introduces the strategic goals of the experiment and connects the various scientific results. Petermann Glacier drains a significant marine-based sector of the northern Greenland Ice Sheet and terminates in a floating ice tongue, one of the largest remaining systems of its kind in the northern hemisphere. Records of the modern state of Petermann Glacier and its past variations are of interest to understand the sensitivity of marine terminating outlet glaciers to change, and to constrain the rates and extent of changes that have actually occurred. With this case study we are learning the rules of large scale dynamics that cannot be understood from modern observations alone. Although past behavior is not an simple analog for the future, and no single system captures all possible behaviors, insights from these case studies can be applied through models to better project how similar systems may change in the future. The Petermann Expedition developed the first comprehensive bathymetric maps of the region, drilled through the floating ice tongue to obtain sub-shelf sediment cores near the grounding line and to monitor sub-ice conditions, recovered a broad array of sediment cores documenting changing oceanic conditions in Petermann Fjord, Hall Basin, and Nares Strait, measured watercolumn properties to trace subsurface watermasses that bring heat from the Arctic Ocean into deep Petermann Fjord to melt the base of the floating ice tongue, developed a detailed record of relative sealevel change on land to constrain past ice loads, and recovered pristine boulders for cosmogenic exposure dating of areal ice retreat on land. Together, these studies are shedding new light on the dynamics of past glaciation in Northwest Greenland, and contributing to fundamental understanding of large marine-terminating outlet glacier systems, which are threatened by global warming and poised to contribute to global sealevel rise in the future. Further information in the Petermann Glacier Experiment is available at https://petermannsglacialhistory.wordpress.com

Spatiotemporal patterns in community structure of macroinvertebrates inhabiting calcareous periphyton mats

USGS Publications Warehouse

Liston, S.E.; Trexler, J.C.

2005-01-01

Calcareous floating periphyton mats in the southern Everglades provide habitat for a diverse macroinvertebrate community that has not been well characterized. Our study described this community in an oligotrophic marsh, compared it with the macroinvertebrate community associated with adjacent epiphytic algae attached to macrophytes in the water column, and detected spatial patterns in density and community structure. The floating periphyton mat (floating mat) and epiphytic algae in the water column (submerged epiphyton) were sampled at 4 sites (???1 km apart) in northern Shark River Slough, Everglades National Park (ENP), in the early (July) and late (November) wet season. Two perpendicular 90-m transects were established at each site and ???100 samples were taken in a nested design. Sites were located in wet-prairie spikerush-dominated sloughs with similar water depths and emergent macrophyte communities. Floating mats were sampled by taking cores (6-cm diameter) that were sorted under magnification to enumerate infauna retained on a 250-??m-mesh sieve and with a maximum dimension >1 mm. Our results showed that floating mats provide habitat for a macroinvertebrate community with higher densities (no. animals/g ash-free dry mass) of Hyalella azteca, Dasyhelea spp., and Cladocera, and lower densities of Chironomidae and Planorbella spp. than communities associated with submerged epiphyton. Densities of the most common taxa increased 3x to 15x from early to late wet season, and community differences between the 2 habitat types became more pronounced. Floating-mat coverage and estimated floating-mat biomass increased 20 to 30%, and 30 to 110%, respectively, at most sites in the late wet season. Some intersite variation was observed in individual taxa, but no consistent spatial pattern in any taxon was detected at any scale (from 0.2 m to 3 km). Floating mats and their resident macroinvertebrate communities are important components in the Everglades food web. This community should be included in environmental monitoring programs because degradation and eventual loss of the calcareous periphyton mat is associated with P enrichment in this ecosystem. ?? 2005 by The North American Benthological Society.

Planted floating bed performance in treatment of eutrophic river water.

PubMed

Bu, Faping; Xu, Xiaoyi

2013-11-01

The objective of the study was to treat eutrophic river water using floating beds and to identify ideal plant species for design of floating beds. Four parallel pilot-scale units were established and vegetated with Canna indica (U1), Accords calamus (U2), Cyperus alternifolius (U3), and Vetiveria zizanioides (U4), respectively, to treat eutrophic river water. The floating bed was made of polyethylene foam, and plants were vegetated on it. Results suggest that the floating bed is a viable alternative for treating eutrophic river water, especially for inhibiting algae growth. When the influent chemical oxygen demand (COD) varied from 6.53 to 18.45 mg/L, total nitrogen (TN) from 6.82 to 12.25 mg/L, total phosphorus (TP) from 0.65 to 1.64 mg/L, and Chla from 6.22 to 66.46 g/m(3), the removal of COD, TN, TP, and Chla was 15.3%-38.4%, 25.4%-48.4%, 16.1%-42.1%, and 29.9 %-88.1%, respectively. Ranked by removal performance, U1 was best, followed by U2, U3, and U4. In the floating bed, more than 60% TN and TP were removed by sedimentation; plant uptake was quantitatively of low importance with an average removal of 20.2% of TN and 29.4% of TP removed. The loss of TN (TP) was of the least importance. Compared with the other three, U1 exhibited better dissolved oxygen (DO) gradient distributions, higher DO levels, higher hydraulic efficiency, and a higher percentage of nutrient removal attributable to plant uptake; in addition, plant development and the volume of nutrient storage in the C. indica tissues outperformed the other three species. C. indica thus could be selected when designing floating beds for the Three Gorges Reservoir region of P. R. China.

Computing at the speed limit (supercomputers)

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

Bernhard, R.

1982-07-01

The author discusses how unheralded efforts in the United States, mainly in universities, have removed major stumbling blocks to building cost-effective superfast computers for scientific and engineering applications within five years. These computers would have sustained speeds of billions of floating-point operations per second (flops), whereas with the fastest machines today the top sustained speed is only 25 million flops, with bursts to 160 megaflops. Cost-effective superfast machines can be built because of advances in very large-scale integration and the special software needed to program the new machines. VLSI greatly reduces the cost per unit of computing power. The developmentmore » of such computers would come at an opportune time. Although the US leads the world in large-scale computer technology, its supremacy is now threatened, not surprisingly, by the Japanese. Publicized reports indicate that the Japanese government is funding a cooperative effort by commercial computer manufacturers to develop superfast computers-about 1000 times faster than modern supercomputers. The US computer industry, by contrast, has balked at attempting to boost computer power so sharply because of the uncertain market for the machines and the failure of similar projects in the past to show significant results.« less

Modelling accumulation of marine plastics in the coastal zone; what are the dominant physical processes?

NASA Astrophysics Data System (ADS)

Critchell, Kay; Lambrechts, Jonathan

2016-03-01

Anthropogenic marine debris, mainly of plastic origin, is accumulating in estuarine and coastal environments around the world causing damage to fauna, flora and habitats. Plastics also have the potential to accumulate in the food web, as well as causing economic losses to tourism and sea-going industries. If we are to manage this increasing threat, we must first understand where debris is accumulating and why these locations are different to others that do not accumulate large amounts of marine debris. This paper demonstrates an advection-diffusion model that includes beaching, settling, resuspension/re-floating, degradation and topographic effects on the wind in nearshore waters to quantify the relative importance of these physical processes governing plastic debris accumulation. The aim of this paper is to prioritise research that will improve modelling outputs in the future. We have found that the physical characteristic of the source location has by far the largest effect on the fate of the debris. The diffusivity, used to parameterise the sub-grid scale movements, and the relationship between debris resuspension/re-floating from beaches and the wind shadow created by high islands also has a dramatic impact on the modelling results. The rate of degradation of macroplastics into microplastics also have a large influence in the result of the modelling. The other processes presented (settling, wind drift velocity) also help determine the fate of debris, but to a lesser degree. These findings may help prioritise research on physical processes that affect plastic accumulation, leading to more accurate modelling, and subsequently management in the future.

Drifters for New Measurements Along River Networks

NASA Astrophysics Data System (ADS)

Davies, J. L.; Niemeier, J. J.; Kruger, A.; Mantilla, R. G.; Ceynar, D. L.

2008-12-01

Inexpensive floating devices and techniques have been developed for a variety of river measurements, including surface flow velocity, water temperature, and light measurements, which serve as a proxy for turbidity. These devices, called Drifters, provide measurements in a Lagrangian reference frame. A Drifter consists of an inexpensive microcontroller, sensors, on-board data storage, a temperature-controlled clock, low-power radio transceiver, two AA batteries, all housed in a small plastic boat hull. As a Drifter floats down a river, the microcontroller periodically awakens and performs a series of measurements. Radio beacons placed on the riverbank transmit location information to the Drifters for georeferencing. Drifters are collected downstream where the data are downloaded for analysis. Drifters can also transmit collected data to the beacons in real time, but at the cost of higher power consumption. The design of the Drifters recognizes the need for accurate determination of travel times along the river network to an outlet of interest. Drifters have the potential to provide a full picture of the spatial distribution of travel times in a basin, opening the door to new understanding of the runoff transport phenomena, and removing the need of calibrated parameters in runoff transport equations of hydrological models. Acquired measurements are overlaid on maps, which provide a new perspective of the spatial distribution of water quality, temperature and velocity in large regions. Drifters have been used to make measurements over a 3-mile stretch of the Iowa River in Iowa City, Iowa, as preparation for a large-scale experiment on the river network of the Clear Creek basin in Iowa.

High-Throughput Computation and the Applicability of Monte Carlo Integration in Fatigue Load Estimation of Floating Offshore Wind Turbines

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

Graf, Peter A.; Stewart, Gordon; Lackner, Matthew

Long-term fatigue loads for floating offshore wind turbines are hard to estimate because they require the evaluation of the integral of a highly nonlinear function over a wide variety of wind and wave conditions. Current design standards involve scanning over a uniform rectangular grid of metocean inputs (e.g., wind speed and direction and wave height and period), which becomes intractable in high dimensions as the number of required evaluations grows exponentially with dimension. Monte Carlo integration offers a potentially efficient alternative because it has theoretical convergence proportional to the inverse of the square root of the number of samples, whichmore » is independent of dimension. In this paper, we first report on the integration of the aeroelastic code FAST into NREL's systems engineering tool, WISDEM, and the development of a high-throughput pipeline capable of sampling from arbitrary distributions, running FAST on a large scale, and postprocessing the results into estimates of fatigue loads. Second, we use this tool to run a variety of studies aimed at comparing grid-based and Monte Carlo-based approaches with calculating long-term fatigue loads. We observe that for more than a few dimensions, the Monte Carlo approach can represent a large improvement in computational efficiency, but that as nonlinearity increases, the effectiveness of Monte Carlo is correspondingly reduced. The present work sets the stage for future research focusing on using advanced statistical methods for analysis of wind turbine fatigue as well as extreme loads.« less

[Association between contraceptive choice and the risk of induced abortion among floating married women of childbearing age].

PubMed

Pei, Li-jun; Zhu, Lin; Guo, Chao; Liu, Hong-yan

2013-07-01

To find the association between factors related to contraception, reproductive health and the risk of induced abortion among floating married women of childbearing age, so as to provide basis for improving the access to health services for floating women of childbearing age. Using data from the reproductive health survey on floating population from five cities in 2005, factors as demographic characteristics, contraceptive choice, settings and access to health services, induced abortion among the floating married women of childbearing age were described. Multivariate logistic regression was used to investigate the association the factors relative to contraception, reproductive health and the risk of induced abortion between 543 cases and 1796 controls. The risks of induced abortion among those under 30-years-old floating married women of childbearing age were 2.08-fold (95%CI:1.26-3.42) of the group at the age of 40 years old. The risk of abortion among floating married women at childbearing age who were taking short-acting contraceptive methods, was 2.56-fold (95%CI:1.84-3.56) of those using the long-acting methods of contraception. The induced abortion risk of floating women at childbearing age who paid the contraceptive implement out of their own pockets, was 1.72-fold (95% CI:1.32-2.24) of those who got it free of charge. The risks of abortion among women who received the contraceptive devices through maternal and child health centers, general hospitals or street residential committees were 2.69-fold (95%CI:1.71-4.22), 2.49-fold (95%CI:1.68-3.68)and 1.81-fold (95%CI:1.20-2.72) of those who received them from urban or rural family planning stations, respectively. The induced abortion risk for women who were ignorant of emergency contraception, was 1.41-fold (95% CI: 1.12-1.78) of those who had the knowledge. The abortion risks of floating women at childbearing age who get the contraceptive knowledge from the colleagues, relatives or friends were 1.85 times (95% CI:1.28-2.67) of those from family planning workers. Factors, including age, short-acting contraceptive methods, paid access to contraceptive implement, ignorance of emergency contraception might largely contribute to the increased risk of induced abortion among floating married women of childbearing age, which called for future attention.

Association of ice and river channel morphology determined using ground-penetrationg radar in the Kuparuk River, Alaska

USGS Publications Warehouse

Best, Heather; McNamara, J.P.; Liberty, Lee M.

2005-01-01

We collected ground-penetrating radar data at 10 sites along the Kuparuk River and its main tributary, the Toolik River, to detect unfrozen water beneath river ice. We used 250 MHz and 500 MHz antennas to image both the ice-water interface and the river channel in late April 2001, when daily high temperatures were consistently freezing and river ice had attained its maximum seasonal thickness. The presence of water below the river ice appears as a strong, horizontal reflection observed in the radar data and is confirmed by drill hole data. A downstream transition occurs from ice that is frozen to the bed, called bedfast ice, to ice that is floating on unfrozen water, called floating ice. This transition in ice type corresponds to a downstream change in channel size that was detected in previously conducted hydraulic geometry surveys of the Kuparuk River. We propose a conceptual model wherein the downstream transition from bedfast ice to floating ice is responsible for an observed step change in channel size due to enhanced bank erosion in large channels by floating ice.

Multiplexed charge-locking device for large arrays of quantum devices

NASA Astrophysics Data System (ADS)

Puddy, R. K.; Smith, L. W.; Al-Taie, H.; Chong, C. H.; Farrer, I.; Griffiths, J. P.; Ritchie, D. A.; Kelly, M. J.; Pepper, M.; Smith, C. G.

2015-10-01

We present a method of forming and controlling large arrays of gate-defined quantum devices. The method uses an on-chip, multiplexed charge-locking system and helps to overcome the restraints imposed by the number of wires available in cryostat measurement systems. The device architecture that we describe here utilises a multiplexer-type scheme to lock charge onto gate electrodes. The design allows access to and control of gates whose total number exceeds that of the available electrical contacts and enables the formation, modulation and measurement of large arrays of quantum devices. We fabricate such devices on n-type GaAs/AlGaAs substrates and investigate the stability of the charge locked on to the gates. Proof-of-concept is shown by measurement of the Coulomb blockade peaks of a single quantum dot formed by a floating gate in the device. The floating gate is seen to drift by approximately one Coulomb oscillation per hour.

Controls on gas transfer velocities in a large river

EPA Science Inventory

The emission of biogenic gases from large rivers can be an important component of regional greenhouse gas budgets. However, emission rate estimates are often poorly constrained due to uncertainties in the air-water gas exchange rate. We used the floating chamber method to estim...

Multi-GNSS PPP-RTK: From Large- to Small-Scale Networks

PubMed Central

Nadarajah, Nandakumaran; Wang, Kan; Choudhury, Mazher

2018-01-01

Precise point positioning (PPP) and its integer ambiguity resolution-enabled variant, PPP-RTK (real-time kinematic), can benefit enormously from the integration of multiple global navigation satellite systems (GNSS). In such a multi-GNSS landscape, the positioning convergence time is expected to be reduced considerably as compared to the one obtained by a single-GNSS setup. It is therefore the goal of the present contribution to provide numerical insights into the role taken by the multi-GNSS integration in delivering fast and high-precision positioning solutions (sub-decimeter and centimeter levels) using PPP-RTK. To that end, we employ the Curtin PPP-RTK platform and process data-sets of GPS, BeiDou Navigation Satellite System (BDS) and Galileo in stand-alone and combined forms. The data-sets are collected by various receiver types, ranging from high-end multi-frequency geodetic receivers to low-cost single-frequency mass-market receivers. The corresponding stations form a large-scale (Australia-wide) network as well as a small-scale network with inter-station distances less than 30 km. In case of the Australia-wide GPS-only ambiguity-float setup, 90% of the horizontal positioning errors (kinematic mode) are shown to become less than five centimeters after 103 min. The stated required time is reduced to 66 min for the corresponding GPS + BDS + Galieo setup. The time is further reduced to 15 min by applying single-receiver ambiguity resolution. The outcomes are supported by the positioning results of the small-scale network. PMID:29614040

Multi-GNSS PPP-RTK: From Large- to Small-Scale Networks.

PubMed

Nadarajah, Nandakumaran; Khodabandeh, Amir; Wang, Kan; Choudhury, Mazher; Teunissen, Peter J G

2018-04-03

Precise point positioning (PPP) and its integer ambiguity resolution-enabled variant, PPP-RTK (real-time kinematic), can benefit enormously from the integration of multiple global navigation satellite systems (GNSS). In such a multi-GNSS landscape, the positioning convergence time is expected to be reduced considerably as compared to the one obtained by a single-GNSS setup. It is therefore the goal of the present contribution to provide numerical insights into the role taken by the multi-GNSS integration in delivering fast and high-precision positioning solutions (sub-decimeter and centimeter levels) using PPP-RTK. To that end, we employ the Curtin PPP-RTK platform and process data-sets of GPS, BeiDou Navigation Satellite System (BDS) and Galileo in stand-alone and combined forms. The data-sets are collected by various receiver types, ranging from high-end multi-frequency geodetic receivers to low-cost single-frequency mass-market receivers. The corresponding stations form a large-scale (Australia-wide) network as well as a small-scale network with inter-station distances less than 30 km. In case of the Australia-wide GPS-only ambiguity-float setup, 90% of the horizontal positioning errors (kinematic mode) are shown to become less than five centimeters after 103 min. The stated required time is reduced to 66 min for the corresponding GPS + BDS + Galieo setup. The time is further reduced to 15 min by applying single-receiver ambiguity resolution. The outcomes are supported by the positioning results of the small-scale network.

The 2008 North Atlantic Spring Bloom Experiment I: Overview and Strategy

NASA Astrophysics Data System (ADS)

D'Asaro, E. A.; Lee, C.; Perry, M.; Fennel, K.; Rehm, E.; Gray, A.; Briggs, N.; Gudmundsson, K.

2008-12-01

The 2008 North Atlantic Spring Bloom Experiment (NAB08) aimed to understand carbon export from this globally important event by combining a new generation of autonomous floats and gliders equipped with a new generation of sensors, and traditional and modern shipboard observational methods. Measurements were made from early April to late June 2008 in a region southeast of Iceland near the JGOFS and MLML sites. Although Sverdrup's classical explanation for the bloom is probably broadly correct, previous observations have revealed a large degree of spatial and temporal variability, often on scales of a few kilometers, which have made detailed tests of Sverdrup's hypothesis difficult. The experiment was designed to continuously sample the bloom and its temporal and spatial 'patchiness' from the pre-bloom, wintertime conditions through the Spring and early Summer. The spatial scales were sampled by 4 Seagliders operating together as a mobile array. Measurements were made in a Lagrangian, water-following coordinate system which minimized the effects of horizontal advection and most clearly separated temporal and spatial scales. The coordinate system was defined by two Lagrangian Floats, one of which was chosen as the center of the Seaglider array. Proper measurement of the bloom by the autonomous vehicles required a robust and redundant array of sensors measuring key physical, chemical and biological variables including temperature, salinity, spectral light, oxygen, multiple optical proxies for carbon (chlorophyll fluorescence, beam-c attenuation and optical backscatter coefficients) and nitrate. Redundant measurements were made whenever possible, with nearly identical sensors on many platforms and multiple sensors measuring similar quantities on the same platform. Such care is clearly necessary, since the current generation of biogeochemical sensor require considerable efforts in calibration and interpretation. The autonomous platforms provided good coverage in space and time, but could not sample the entire range of processes that control the bloom. More detailed measurements and multiple calibrations of the autonomous platforms were made on 4 cruises, particularly a 21-day Knorr cruise in May 2008 that included collaborators from five US and five international institutions. These measurements included nutrients; particulate organic carbon and nitrogen; characterization of plankton composition and physiology by size, imaging, genomics, HPLC pigments, absorption spectra, 14C-primary productivity, and variable fluorescence; particle flux from floating sediment traps; and ADCP and CTD measurements. The experiment clearly demonstrated the ability of autonomous platforms to make biogeochemically relevant measurements of blooms. Its success, however, required intensive shipboard support for sensor calibration and interpretation. Further development of sensor technology, validation protocols, and understanding is clearly required if these measurements are to made routinely and easily.

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

Hung, Cheng-Hung

The main objective of this project was to develop a low-cost integrated substrate for rigid OLED solid-state lighting produced at a manufacturing scale. The integrated substrates could include combinations of soda lime glass substrate, light extraction layer, and an anode layer (i.e., Transparent Conductive Oxide, TCO). Over the 3 + year course of the project, the scope of work was revised to focus on the development of a glass substrates with an internal light extraction (IEL) layer. A manufacturing-scale float glass on-line particle embedding process capable of producing an IEL glass substrate having a thickness of less than 1.7mm andmore » an area larger than 500mm x 400mm was demonstrated. Substrates measuring 470mm x 370mm were used in the OLED manufacturing process for fabricating OLED lighting panels in single pixel devices as large as 120.5mm x 120.5mm. The measured light extraction efficiency (calculated as external quantum efficiency, EQE) for on-line produced IEL samples (>50%) met the project’s initial goal.« less

Stream-water storage in the ocean using an impermeable membrane

NASA Astrophysics Data System (ADS)

Murabayashi, E. T.; Asuka, M.; Yamada, R.; Fok, Y. S.; Gee, H. K.

1983-05-01

The conceptual feasibility of storing fresh water in the ocean was investigated using a plastic membrane as the reservoir liner. In the initial phase, two physical hydraulic models were constructed to test the concept. The first was a water-filled, glass-sided box to observe the movement and reaction of the membrane to various simulated effects of currents, waves, and sediment deposition. The second was a 1:400-scale model (6.7 x 6.1 m) of West Loch, Pearl Harbor (a potential field application site), with 1:24 vertical exaggeration for similitude. The curtain method was used because it can enclose a large water body. The effect of wind, waves, tides, and currents on the curtain were simulated and the reactions observed. Although modeling is a useful tool for investigating initial concepts, its direct field application is limited because of scaling. Curtains, floating reservoirs, and bags were constructed of polyethylene sheets and deployed. All worked well after modifications were made following initial testing.

Massive Cloud-Based Big Data Processing for Ocean Sensor Networks and Remote Sensing

NASA Astrophysics Data System (ADS)

Schwehr, K. D.

2017-12-01

Until recently, the work required to integrate and analyze data for global-scale environmental issues was prohibitive both in cost and availability. Traditional desktop processing systems are not able to effectively store and process all the data, and super computer solutions are financially out of the reach of most people. The availability of large-scale cloud computing has created tools that are usable by small groups and individuals regardless of financial resources or locally available computational resources. These systems give scientists and policymakers the ability to see how critical resources are being used across the globe with little or no barrier to entry. Google Earth Engine has the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra, MODIS Aqua, and Global Land Data Assimilation Systems (GLDAS) data catalogs available live online. Here we demonstrate these data to calculate the correlation between lagged chlorophyll and rainfall to identify areas of eutrophication, matching these events to ocean currents from datasets like HYbrid Coordinate Ocean Model (HYCOM) to check if there are constraints from oceanographic configurations. The system can provide addition ground truth with observations from sensor networks like the International Comprehensive Ocean-Atmosphere Data Set / Voluntary Observing Ship (ICOADS/VOS) and Argo floats. This presentation is intended to introduce users to the datasets, programming idioms, and functionality of Earth Engine for large-scale, data-driven oceanography.

Low-Complexity Polynomial Channel Estimation in Large-Scale MIMO With Arbitrary Statistics

NASA Astrophysics Data System (ADS)

Shariati, Nafiseh; Bjornson, Emil; Bengtsson, Mats; Debbah, Merouane

2014-10-01

This paper considers pilot-based channel estimation in large-scale multiple-input multiple-output (MIMO) communication systems, also known as massive MIMO, where there are hundreds of antennas at one side of the link. Motivated by the fact that computational complexity is one of the main challenges in such systems, a set of low-complexity Bayesian channel estimators, coined Polynomial ExpAnsion CHannel (PEACH) estimators, are introduced for arbitrary channel and interference statistics. While the conventional minimum mean square error (MMSE) estimator has cubic complexity in the dimension of the covariance matrices, due to an inversion operation, our proposed estimators significantly reduce this to square complexity by approximating the inverse by a L-degree matrix polynomial. The coefficients of the polynomial are optimized to minimize the mean square error (MSE) of the estimate. We show numerically that near-optimal MSEs are achieved with low polynomial degrees. We also derive the exact computational complexity of the proposed estimators, in terms of the floating-point operations (FLOPs), by which we prove that the proposed estimators outperform the conventional estimators in large-scale MIMO systems of practical dimensions while providing a reasonable MSEs. Moreover, we show that L needs not scale with the system dimensions to maintain a certain normalized MSE. By analyzing different interference scenarios, we observe that the relative MSE loss of using the low-complexity PEACH estimators is smaller in realistic scenarios with pilot contamination. On the other hand, PEACH estimators are not well suited for noise-limited scenarios with high pilot power; therefore, we also introduce the low-complexity diagonalized estimator that performs well in this regime. Finally, we ...

14 CFR 23.629 - Flutter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... significant elastic, inertial, and aerodynamic forces, and (2) Propeller, engine, engine mount, and airplane... in use to airplanes without large mass concentrations (such as engines, floats, or fuel tanks in...

14 CFR 23.629 - Flutter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... significant elastic, inertial, and aerodynamic forces, and (2) Propeller, engine, engine mount, and airplane... in use to airplanes without large mass concentrations (such as engines, floats, or fuel tanks in...

In situ free-floating craniectomy: an unusual cause of chronic post-traumatic cephalalgia

PubMed Central

Kaliaperumal, Chandrasekaran; Raveendran, Savitha

2012-01-01

We describe a case of post-traumatic cephalalgia in a 54-year-old man with chronic right parieto-occipital headache 3 years posthead injury. At the initial presentation, his Glasgow Coma Scale (GCS) was 13/15 and CT brain revealed an acute subdural haematoma with fronto-temporal contusions. After 24 h his GCS dropped to 8/15 and subsequently he underwent a right-sided craniotomy and evacuation of the subdural haematoma and contusionectomy and intracranial pressure monitoring. To manage the cerebral oedema, the cranial bone flap was left in situ free-floating and was managed in an intensive care setting. He made good clinical recovery and 3 months postoperatively he complained of right-sided headache not relieved with medication and occipital nerve block. Three years later he underwent an exploration of the previous craniotomy scalp wound and the free-floating bone flap under the scalp was immobilised. The headache completely resolved following the procedure and is currently asymptomatic. PMID:22891026

Dynamic Performance Investigation of A Spar-Type Floating Wind Turbine Under Different Sea Conditions

NASA Astrophysics Data System (ADS)

Wang, Han; Hu, Zhi-qiang; Meng, Xiang-yin

2018-06-01

Both numerical calculation and model test are important techniques to study and forecast the dynamic responses of the floating offshore wind turbine (FOWT). However, both the methods have their own limitations at present. In this study, the dynamic responses of a 5 MW OC3 spar-type floating wind turbine designed for a water depth of 200 m are numerically investigated and validated by a 1:50 scaled model test. Moreover, the discrepancies between the numerical calculations and model tests are obtained and discussed. According to the discussions, it is found that the surge and pitch are coupled with the mooring tensions, but the heave is independent of them. Surge and pitch are mainly induced by wave under wind wave conditions. Wind and current will induce the low-frequency average responses, while wave will induce the fluctuation ranges of the responses. In addition, wave will induce the wavefrequency responses but wind and current will restrain the ranges of the responses.

Real-Time Spaceborne Synthetic Aperture Radar Float-Point Imaging System Using Optimized Mapping Methodology and a Multi-Node Parallel Accelerating Technique

PubMed Central

Li, Bingyi; Chen, Liang; Yu, Wenyue; Xie, Yizhuang; Bian, Mingming; Zhang, Qingjun; Pang, Long

2018-01-01

With the development of satellite load technology and very large-scale integrated (VLSI) circuit technology, on-board real-time synthetic aperture radar (SAR) imaging systems have facilitated rapid response to disasters. A key goal of the on-board SAR imaging system design is to achieve high real-time processing performance under severe size, weight, and power consumption constraints. This paper presents a multi-node prototype system for real-time SAR imaging processing. We decompose the commonly used chirp scaling (CS) SAR imaging algorithm into two parts according to the computing features. The linearization and logic-memory optimum allocation methods are adopted to realize the nonlinear part in a reconfigurable structure, and the two-part bandwidth balance method is used to realize the linear part. Thus, float-point SAR imaging processing can be integrated into a single Field Programmable Gate Array (FPGA) chip instead of relying on distributed technologies. A single-processing node requires 10.6 s and consumes 17 W to focus on 25-km swath width, 5-m resolution stripmap SAR raw data with a granularity of 16,384 × 16,384. The design methodology of the multi-FPGA parallel accelerating system under the real-time principle is introduced. As a proof of concept, a prototype with four processing nodes and one master node is implemented using a Xilinx xc6vlx315t FPGA. The weight and volume of one single machine are 10 kg and 32 cm × 24 cm × 20 cm, respectively, and the power consumption is under 100 W. The real-time performance of the proposed design is demonstrated on Chinese Gaofen-3 stripmap continuous imaging. PMID:29495637

On the mesoscale monitoring capability of Argo floats in the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Sánchez-Román, Antonio; Ruiz, Simón; Pascual, Ananda; Mourre, Baptiste; Guinehut, Stéphanie

2017-03-01

In this work a simplified observing system simulation experiment (OSSE) approach is used to investigate which Argo design sampling in the Mediterranean Sea would be necessary to properly capture the mesoscale dynamics in this basin. The monitoring of the mesoscale features is not an initial objective of the Argo network. However, it is an interesting question from the perspective of future network extensions in order to improve the ocean state estimates. The true field used to conduct the OSSEs is provided by a specific altimetry-gridded merged product for the Mediterranean Sea. Synthetic observations were obtained by sub-sampling this Nature Run according to different configurations of the ARGO network. The observation errors required to perform the OSSEs were obtained through the comparison of sea level anomalies (SLAs) from altimetry and dynamic height anomalies (DHAs) computed from the real in situ Argo network. This analysis also contributes to validate satellite SLAs with an increased confidence. The simulation experiments show that a configuration similar to the current Argo array in the Mediterranean (with a spatial resolution of 2° × 2°) is only able to recover the large-scale signals of the basin. Increasing the spatial resolution to nearly 75 km × 75 km, allows the capture of most of the mesoscale signal in the basin and to retrieve the SLA field with a RMSE of 3 cm for spatial scales larger than 150 km, similar to those presently captured by the altimetry. This would represent a theoretical reduction of 40 % of the actual RMSE. Such a high-resolution Argo array composed of around 450 floats, cycling every 10 days, is expected to increase the actual network cost by approximately a factor of 6.

Long-term assessment at field scale of Floating Treatment Wetlands for improvement of water quality and provision of ecosystem services in a eutrophic urban pond.

PubMed

Olguín, Eugenia J; Sánchez-Galván, Gloria; Melo, Francisco J; Hernández, Víctor J; González-Portela, Ricardo E

2017-04-15

Pollution of urban water bodies requires stringent control measures and the development of low-cost and highly efficient alternative technologies. In contrast to Constructed Wetlands, Floating Treatment Wetlands (FTWs) have the advantage of not requiring large surface of land since they operate in situ. However, there is limited information about their long-term evaluation while operating at field scale. The aim of this work was to assess the performance of FTWs using a combination of Pontederia sagittata and Cyperus papyrus for the improvement of the water quality and provision of ecosystem services of a eutrophic urban pond. The FTWs were built with low-cost material easy to acquire and to ensemble. Two FTWs (17.5m 2 and 33m 2 ) located in Pond 1 within a complex of 4 urban artificial ponds were evaluated for two years. They promoted an increase in the dissolved oxygen (D.O.) within a range of 15 to 67%, a removal of fecal coliforms in the range of 9 to 86% and a nitrate removal in the range of 9 to 76%. The plant productivity reached a maximum of 363g dm m -2 d -1 in the FTW1 and 536g dm m -2 d -1 in the FTW2 during the period March-June 2016. The TKN and the TP content in the plant were in the range of 18.3 to 28.1 and of 0.05 to 0.196gkg -1 dry matter, respectively. In conclusion, the tested FTWs have proved to be a very beneficial low-cost technology for the improvement of water quality and provision of ecosystem services. Copyright © 2017 Elsevier B.V. All rights reserved.

The Metropolis Monte Carlo method with CUDA enabled Graphic Processing Units

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

Hall, Clifford; School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Dr., Fairfax, VA 22030; Ji, Weixiao

2014-02-01

We present a CPU–GPU system for runtime acceleration of large molecular simulations using GPU computation and memory swaps. The memory architecture of the GPU can be used both as container for simulation data stored on the graphics card and as floating-point code target, providing an effective means for the manipulation of atomistic or molecular data on the GPU. To fully take advantage of this mechanism, efficient GPU realizations of algorithms used to perform atomistic and molecular simulations are essential. Our system implements a versatile molecular engine, including inter-molecule interactions and orientational variables for performing the Metropolis Monte Carlo (MMC) algorithm,more » which is one type of Markov chain Monte Carlo. By combining memory objects with floating-point code fragments we have implemented an MMC parallel engine that entirely avoids the communication time of molecular data at runtime. Our runtime acceleration system is a forerunner of a new class of CPU–GPU algorithms exploiting memory concepts combined with threading for avoiding bus bandwidth and communication. The testbed molecular system used here is a condensed phase system of oligopyrrole chains. A benchmark shows a size scaling speedup of 60 for systems with 210,000 pyrrole monomers. Our implementation can easily be combined with MPI to connect in parallel several CPU–GPU duets. -- Highlights: •We parallelize the Metropolis Monte Carlo (MMC) algorithm on one CPU—GPU duet. •The Adaptive Tempering Monte Carlo employs MMC and profits from this CPU—GPU implementation. •Our benchmark shows a size scaling-up speedup of 62 for systems with 225,000 particles. •The testbed involves a polymeric system of oligopyrroles in the condensed phase. •The CPU—GPU parallelization includes dipole—dipole and Mie—Jones classic potentials.« less

A Method for Measuring Fishing Effort by Small-Scale Fish Aggregating Device (FAD) Fishers from the Commonwealth of Dominica

ERIC Educational Resources Information Center

Alvard, Michael; McGaffey, Ethan; Carlson, David

2015-01-01

We used global positioning system (GPS) technology and tracking analysis to measure fishing effort by marine, small-scale, fish aggregating device (FAD) fishers of the Commonwealth of Dominica. FADs are human-made structures designed to float on the surface of the water and attract fish. They are also prone to common pool resource problems. To…

Dynamic response signatures of a scaled model platform for floating wind turbines in an ocean wave basin

PubMed Central

Jaksic, V.; O'Shea, R.; Cahill, P.; Murphy, J.; Mandic, D. P.; Pakrashi, V.

2015-01-01

Understanding of dynamic behaviour of offshore wind floating substructures is extremely important in relation to design, operation, maintenance and management of floating wind farms. This paper presents assessment of nonlinear signatures of dynamic responses of a scaled tension-leg platform (TLP) in a wave tank exposed to different regular wave conditions and sea states characterized by the Bretschneider, the Pierson–Moskowitz and the JONSWAP spectra. Dynamic responses of the TLP were monitored at different locations using load cells, a camera-based motion recognition system and a laser Doppler vibrometer. The analysis of variability of the TLP responses and statistical quantification of their linearity or nonlinearity, as non-destructive means of structural monitoring from the output-only condition, remains a challenging problem. In this study, the delay vector variance (DVV) method is used to statistically study the degree of nonlinearity of measured response signals from a TLP. DVV is observed to create a marker estimating the degree to which a change in signal nonlinearity reflects real-time behaviour of the structure and also to establish the sensitivity of the instruments employed to these changes. The findings can be helpful in establishing monitoring strategies and control strategies for undesirable levels or types of dynamic response and can help to better estimate changes in system characteristics over the life cycle of the structure. PMID:25583866

Web-based visualization of very large scientific astronomy imagery

NASA Astrophysics Data System (ADS)

Bertin, E.; Pillay, R.; Marmo, C.

2015-04-01

Visualizing and navigating through large astronomy images from a remote location with current astronomy display tools can be a frustrating experience in terms of speed and ergonomics, especially on mobile devices. In this paper, we present a high performance, versatile and robust client-server system for remote visualization and analysis of extremely large scientific images. Applications of this work include survey image quality control, interactive data query and exploration, citizen science, as well as public outreach. The proposed software is entirely open source and is designed to be generic and applicable to a variety of datasets. It provides access to floating point data at terabyte scales, with the ability to precisely adjust image settings in real-time. The proposed clients are light-weight, platform-independent web applications built on standard HTML5 web technologies and compatible with both touch and mouse-based devices. We put the system to the test and assess the performance of the system and show that a single server can comfortably handle more than a hundred simultaneous users accessing full precision 32 bit astronomy data.

MemFlash device: floating gate transistors as memristive devices for neuromorphic computing

NASA Astrophysics Data System (ADS)

Riggert, C.; Ziegler, M.; Schroeder, D.; Krautschneider, W. H.; Kohlstedt, H.

2014-10-01

Memristive devices are promising candidates for future non-volatile memory applications and mixed-signal circuits. In the field of neuromorphic engineering these devices are especially interesting to emulate neuronal functionality. Therefore, new materials and material combinations are currently investigated, which are often not compatible with Si-technology processes. The underlying mechanisms of the device often remain unclear and are paired with low device endurance and yield. These facts define the current most challenging development tasks towards a reliable memristive device technology. In this respect, the MemFlash concept is of particular interest. A MemFlash device results from a diode configuration wiring scheme of a floating gate transistor, which enables the persistent device resistance to be varied according to the history of the charge flow through the device. In this study, we investigate the scaling conditions of the floating gate oxide thickness with respect to possible applications in the field of neuromorphic engineering. We show that MemFlash cells exhibit essential features with respect to neuromorphic applications. In particular, cells with thin floating gate oxides show a limited synaptic weight growth together with low energy dissipation. MemFlash cells present an attractive alternative for state-of-art memresitive devices. The emulation of associative learning is discussed by implementing a single MemFlash cell in an analogue circuit.

IIPImage: Large-image visualization

NASA Astrophysics Data System (ADS)

Pillay, Ruven

2014-08-01

IIPImage is an advanced high-performance feature-rich image server system that enables online access to full resolution floating point (as well as other bit depth) images at terabyte scales. Paired with the VisiOmatic (ascl:1408.010) celestial image viewer, the system can comfortably handle gigapixel size images as well as advanced image features such as both 8, 16 and 32 bit depths, CIELAB colorimetric images and scientific imagery such as multispectral images. Streaming is tile-based, which enables viewing, navigating and zooming in real-time around gigapixel size images. Source images can be in either TIFF or JPEG2000 format. Whole images or regions within images can also be rapidly and dynamically resized and exported by the server from a single source image without the need to store multiple files in various sizes.

Lightweight Mechanical Metamaterials with Tunable Negative Thermal Expansion

NASA Astrophysics Data System (ADS)

Wang, Qiming; Jackson, Julie A.; Ge, Qi; Hopkins, Jonathan B.; Spadaccini, Christopher M.; Fang, Nicholas X.

2016-10-01

Ice floating on water is a great manifestation of negative thermal expansion (NTE) in nature. The limited examples of natural materials possessing NTE have stimulated research on engineered structures. Previous studies on NTE structures were mostly focused on theoretical design with limited experimental demonstration in two-dimensional planar geometries. In this work, aided with multimaterial projection microstereolithography, we experimentally fabricate lightweight multimaterial lattices that exhibit significant negative thermal expansion in three directions and over a temperature range of 170 degrees. Such NTE is induced by the structural interaction of material components with distinct thermal expansion coefficients. The NTE can be tuned over a large range by varying the thermal expansion coefficient difference between constituent beams and geometrical arrangements. Our experimental results match qualitatively with a simple scaling law and quantitatively with computational models.

An Application-Based Performance Characterization of the Columbia Supercluster

NASA Technical Reports Server (NTRS)

Biswas, Rupak; Djomehri, Jahed M.; Hood, Robert; Jin, Hoaqiang; Kiris, Cetin; Saini, Subhash

2005-01-01

Columbia is a 10,240-processor supercluster consisting of 20 Altix nodes with 512 processors each, and currently ranked as the second-fastest computer in the world. In this paper, we present the performance characteristics of Columbia obtained on up to four computing nodes interconnected via the InfiniBand and/or NUMAlink4 communication fabrics. We evaluate floating-point performance, memory bandwidth, message passing communication speeds, and compilers using a subset of the HPC Challenge benchmarks, and some of the NAS Parallel Benchmarks including the multi-zone versions. We present detailed performance results for three scientific applications of interest to NASA, one from molecular dynamics, and two from computational fluid dynamics. Our results show that both the NUMAlink4 and the InfiniBand hold promise for application scaling to a large number of processors.

Predicting vehicle fuel consumption patterns using floating vehicle data.

PubMed

Du, Yiman; Wu, Jianping; Yang, Senyan; Zhou, Liutong

2017-09-01

The status of energy consumption and air pollution in China is serious. It is important to analyze and predict the different fuel consumption of various types of vehicles under different influence factors. In order to fully describe the relationship between fuel consumption and the impact factors, massive amounts of floating vehicle data were used. The fuel consumption pattern and congestion pattern based on large samples of historical floating vehicle data were explored, drivers' information and vehicles' parameters from different group classification were probed, and the average velocity and average fuel consumption in the temporal dimension and spatial dimension were analyzed respectively. The fuel consumption forecasting model was established by using a Back Propagation Neural Network. Part of the sample set was used to train the forecasting model and the remaining part of the sample set was used as input to the forecasting model. Copyright © 2017. Published by Elsevier B.V.

Health Insurance Coverage and Its Impact on Medical Cost: Observations from the Floating Population in China

PubMed Central

Zhao, Yinjun; Kang, Bowei; Liu, Yawen; Li, Yichong; Shi, Guoqing; Shen, Tao; Jiang, Yong; Zhang, Mei; Zhou, Maigeng; Wang, Limin

2014-01-01

Background China has the world's largest floating (migrant) population, which has characteristics largely different from the rest of the population. Our goal is to study health insurance coverage and its impact on medical cost for this population. Methods A telephone survey was conducted in 2012. 644 subjects were surveyed. Univariate and multivariate analysis were conducted on insurance coverage and medical cost. Results 82.2% of the surveyed subjects were covered by basic insurance at hometowns with hukou or at residences. Subjects' characteristics including age, education, occupation, and presence of chronic diseases were associated with insurance coverage. After controlling for confounders, insurance coverage was not significantly associated with gross or out-of-pocket medical cost. Conclusion For the floating population, health insurance coverage needs to be improved. Policy interventions are needed so that health insurance can have a more effective protective effect on cost. PMID:25386914

ISS Plasma Interaction: Measurements and Modeling

NASA Technical Reports Server (NTRS)

Barsamian, H.; Mikatarian, R.; Alred, J.; Minow, J.; Koontz, S.

2004-01-01

Ionospheric plasma interaction effects on the International Space Station are discussed in the following paper. The large structure and high voltage arrays of the ISS represent a complex system interacting with LEO plasma. Discharge current measurements made by the Plasma Contactor Units and potential measurements made by the Floating Potential Probe delineate charging and magnetic induction effects on the ISS. Based on theoretical and physical understanding of the interaction phenomena, a model of ISS plasma interaction has been developed. The model includes magnetic induction effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. Based on these phenomena, the Plasma Interaction Model has been developed. Limited verification of the model has been performed by comparison of Floating Potential Probe measurement data to simulations. The ISS plasma interaction model will be further tested and verified as measurements from the Floating Potential Measurement Unit become available, and construction of the ISS continues.

Energy-band engineering for tunable memory characteristics through controlled doping of reduced graphene oxide.

PubMed

Han, Su-Ting; Zhou, Ye; Yang, Qing Dan; Zhou, Li; Huang, Long-Biao; Yan, Yan; Lee, Chun-Sing; Roy, Vellaisamy A L

2014-02-25

Tunable memory characteristics are used in multioperational mode circuits where memory cells with various functionalities are needed in one combined device. It is always a challenge to obtain control over threshold voltage for multimode operation. On this regard, we use a strategy of shifting the work function of reduced graphene oxide (rGO) in a controlled manner through doping gold chloride (AuCl3) and obtained a gradient increase of rGO work function. By inserting doped rGO as floating gate, a controlled threshold voltage (Vth) shift has been achieved in both p- and n-type low voltage flexible memory devices with large memory window (up to 4 times for p-type and 8 times for n-type memory devices) in comparison with pristine rGO floating gate memory devices. By proper energy band engineering, we demonstrated a flexible floating gate memory device with larger memory window and controlled threshold voltage shifts.

Processing large remote sensing image data sets on Beowulf clusters

USGS Publications Warehouse

Steinwand, Daniel R.; Maddox, Brian; Beckmann, Tim; Schmidt, Gail

2003-01-01

High-performance computing is often concerned with the speed at which floating- point calculations can be performed. The architectures of many parallel computers and/or their network topologies are based on these investigations. Often, benchmarks resulting from these investigations are compiled with little regard to how a large dataset would move about in these systems. This part of the Beowulf study addresses that concern by looking at specific applications software and system-level modifications. Applications include an implementation of a smoothing filter for time-series data, a parallel implementation of the decision tree algorithm used in the Landcover Characterization project, a parallel Kriging algorithm used to fit point data collected in the field on invasive species to a regular grid, and modifications to the Beowulf project's resampling algorithm to handle larger, higher resolution datasets at a national scale. Systems-level investigations include a feasibility study on Flat Neighborhood Networks and modifications of that concept with Parallel File Systems.

Batch Immunostaining for Large-Scale Protein Detection in the Whole Monkey Brain

PubMed Central

Zangenehpour, Shahin; Burke, Mark W.; Chaudhuri, Avi; Ptito, Maurice

2009-01-01

Immunohistochemistry (IHC) is one of the most widely used laboratory techniques for the detection of target proteins in situ. Questions concerning the expression pattern of a target protein across the entire brain are relatively easy to answer when using IHC in small brains, such as those of rodents. However, answering the same questions in large and convoluted brains, such as those of primates presents a number of challenges. Here we present a systematic approach for immunodetection of target proteins in an adult monkey brain. This approach relies on the tissue embedding and sectioning methodology of NeuroScience Associates (NSA) as well as tools developed specifically for batch-staining of free-floating sections. It results in uniform staining of a set of sections which, at a particular interval, represents the entire brain. The resulting stained sections can be subjected to a wide variety of analytical procedures in order to measure protein levels, the population of neurons expressing a certain protein. PMID:19636291

Eddy Seeding in the Labrador Sea: a Submerged Autonomous Launching Platform (SALP) Application

NASA Astrophysics Data System (ADS)

Furey, Heather H.; Femke de Jong, M.; Bower, Amy S.

2013-04-01

A simplified Submerged Autonomous Launch Platform (SALP) was used to release profiling floats into warm-core Irminger Rings (IRs) in order to investigate their vertical structure and evolution in the Labrador Sea from September 2007 - September 2009. IRs are thought to play an important role in restratification after convection in the Labrador Sea. The SALP is designed to release surface drifters or subsurface floats serially from a traditional ocean mooring, using real-time ocean measurements as criteria for launch. The original prototype instrument used properties measured at multiple depths, with information relayed to the SALP controller via acoustic modems. In our application, two SALP carousels were attached at 500 meters onto a heavily-instrumented deep water mooring, in the path of recently-shed IRs off the west Greenland shelf. A release algorithm was designed to use temperature and pressure measured at the SALP depth only to release one or two APEX profiling drifters each time an IR passed the mooring, using limited historical observations to set release thresholds. Mechanically and electronically, the SALP worked well: out of eleven releases, there was only one malfunction when a float was caught in the cage after the burn-wire had triggered. However, getting floats trapped in eddies met with limited success due to problems with the release algorithm and float ballasting. Out of seven floats launched from the platform using oceanographic criteria, four were released during warm water events that were not related to passing IRs. Also, after float release, it took on average about 2.6 days for the APEX to adjust from its initial ballast depth, about 600 meters, to its park point of 300 meters, leaving the float below the trapped core of water in the IRs. The other mooring instruments (at depths of 100 to 3000 m), revealed that 12 IRs passed by the mooring in the 2-year monitoring period. With this independent information, we were able to assess and improve the release algorithm, still based on ocean conditions measured only at one depth. We found that much better performance could have been achieved with an algorithm that detected IRs based on a temperature difference from a long-term running mean rather than a fixed temperature threshold. This highlights the challenge of designing an appropriate release strategy with limited a priori information on the amplitude and time scales of the background variability.

[Observation on the clinical efficacy of shoulder pain in post-stroke shoulder-hand syndrome treated with floating acupuncture and rehabilitation training].

PubMed

Wang, Jun; Cui, Xiao; Ni, Huan-Huan; Huang, Chun-Shui; Zhou, Cui-Xia; Wu, Ji; Shi, Jun-Chao; Wu, Yi

2013-04-01

To compare the efficacy difference in the treatment of shoulder pain in post-stroke shoulder-hand syndrome among floating acupuncture, oral administration of western medicine and local fumigation of Chinese herbs. Ninety cases of post-stroke shoulder-hand syndrome (stage I) were randomized into a floating acupuncture group, a western medicine group and a local Chinese herbs fumigation group, 30 cases in each one. In the floating acupuncture group, two obvious tender points were detected on the shoulder and the site 80-100 mm inferior to each tender point was taken as the inserting point and stimulated with floating needling technique. In the western medicine group, mobic 7.5 mg was prescribed for oral administration. In the local Chinese herbs fumigation group, the formula for activating blood circulation and relaxing tendon was used for local fumigation. All the patients in three groups received rehabilitation training. The floating acupuncture, oral administration of western medicine, local Chinese herbs fumigation and rehabilitation training were given once a day respectively in corresponding group and the cases were observed for 1 month. The visual analogue scale (VAS) and Takagishi shoulder joint function assessment were adopted to evaluate the dynamic change of the patients with shoulder pain before and after treatment in three groups. The modified Barthel index was used to evaluate the dynamic change of daily life activity of the patients in three groups. With floating acupuncture, shoulder pain was relieved and the daily life activity was improved in the patients with post-stroke shoulder-hand syndrome, which was superior to the oral administration of western medicine and local Chinese herbs fumigation (P < 0.01). With local Chinese herbs fumigation, the improvement of shoulder pain was superior to the oral administration of western medicine. The difference in the improvement of daily life activity was not significant statistically between the local Chinese herbs fumigation and oral administration of western medicine, the efficacy was similar between these two therapies (P > 0.05). The floating acupuncture relieves shoulder pain of the patients with post-stroke shoulder-hand syndrome promptly and effectively, and the effects on shoulder pain and the improvements of daily life activity are superior to that of the oral administration of western medicine and local Chinese herbs fumigation.

33 CFR 165.2030 - Pacific Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS AREAS Protection of Naval... States, whether the large U.S. naval vessel is underway, anchored, moored, or within a floating dry dock...

When ice meets water: Sub-aqueous melt and its relevance in various settings

NASA Astrophysics Data System (ADS)

Truffer, M.; Motyka, R. J.

2014-12-01

The largest glacier changes are primarily observed in settings where ice flows into a proglacial water body. However, the responses to this interaction are not uniform. Rapidly retreating glaciers can occur in close vicinity to advancing ones. Calving styles and glacier morphologies vary greatly as well. Temperate lake-calving glaciers frequently exhibit floating tongues; but this is rarely observed on temperate tidewater glaciers. Calving styles range from mostly sub-aerial calving to full-thickness calving to slow detachment of large ice bergs. In addition to the more obvious mechanical calving, glaciers lose mass at their termini through sub-aqueous melting. Melt rates of submerged ice have been shown to vary over several orders of magnitudes, and can range up to several meters per day. This large range is a consequence of different proglacial water temperatures, and of different modes of water transport. Water convection in proglacial water bodies can be driven by winds and tides, but subglacial water discharge is commonly the strongest and most variable driver. Here we attempt to relate the variability of forcings and melt rates to the various morphologies and calving styles of different water-terminating glaciers. The highest melt rates are observed at low-latitude tidewater glaciers, where ocean water can be warm (7 - 10 deg C) and subglacial discharge high. In such settings, sub-aqueous melt can reach the same magnitude as ice flux delivered to the terminus and it can control ice terminus position. Polar tidewater glaciers, such as those in Greenland, often exhibit floating tongues. Although melt rates are likely much lower, they can have a large effect under a floating tongue because of the much larger exposure of ice to water. Changes in melt rates can therefore affect the stability of such floating tongues. Low melt rates occur at some ice shelves at high latitudes, where the temperature and freshwater forcings are small. This situation can also occur at temperate lake-calving glaciers, which often flow into lakes of near freezing temperatures. Due to the very small density differences between subglacial discharge and ambient lake water, convection below the floating tongue is minor or non-existent.. This is in great contrast to fresh water entering a saline environment.

Parametric studies on floating pad journal bearing for high speed cryogenic turboexpanders

NASA Astrophysics Data System (ADS)

Jain, A.; Jadhav, M. M.; Karimulla, S.; Chakravarty, A.

2017-12-01

Most modern medium and large capacity helium liquefaction/refrigeration plants employ high speed cryogenic turboexpanders in their refrigeration/liquefaction cycles as active cooling devices. The operating speed of these turboexpanders is in the range of 3000-5000 Hz and hence specialized types of bearings are required. Floating pad journal bearing, which is a special type of tilting pad journal bearing, where mechanical pivots are absent and pads are fully suspended in gas, can be a good solution for stable operation of these high speed compact rotors. The pads are separated from shaft as well as from housing by fluid film between them, and both these sides of pad are interconnected by a network of feed holes. The work presented in this article aims to characterize floating pad journal bearings through parametric studies. The steady state performance characteristics of the bearing are represented by load capacity, stiffness coefficients and heat generation rate of the bearing. The geometrical parameters such as bearing clearances, preload of pads, etc. are varied and performance characteristics of the floating pad journal bearing are studied and presented. The dependence of stiffness coefficients on rotational speed of shaft is also analyzed.

Dynamic behavior and deformation analysis of the fish cage system using mass-spring model

NASA Astrophysics Data System (ADS)

Lee, Chun Woo; Lee, Jihoon; Park, Subong

2015-06-01

Fish cage systems are influenced by various oceanic conditions, and the movements and deformation of the system by the external forces can affect the safety of the system itself, as well as the species of fish being cultivated. Structural durability of the system against environmental factors has been major concern for the marine aquaculture system. In this research, a mathematical model and a simulation method were presented for analyzing the performance of the large-scale fish cage system influenced by current and waves. The cage system consisted of netting, mooring ropes, floats, sinkers and floating collar. All the elements were modeled by use of the mass-spring model. The structures were divided into finite elements and mass points were placed at the mid-point of each element, and mass points were connected by springs without mass. Each mass point was applied to external and internal forces, and total force was calculated in every integration step. The computation method was applied to the dynamic simulation of the actual fish cage systems rigged with synthetic fiber and copper wire simultaneously influenced by current and waves. Here, we also tried to find a relevant ratio between buoyancy and sinking force of the fish cages. The simulation results provide improved understanding of the behavior of the structure and valuable information concerning optimum ratio of the buoyancy to sinking force according to current speeds.

On the scalability of the Albany/FELIX first-order Stokes approximation ice sheet solver for large-scale simulations of the Greenland and Antarctic ice sheets

DOE PAGES

Tezaur, Irina K.; Tuminaro, Raymond S.; Perego, Mauro; ...

2015-01-01

We examine the scalability of the recently developed Albany/FELIX finite-element based code for the first-order Stokes momentum balance equations for ice flow. We focus our analysis on the performance of two possible preconditioners for the iterative solution of the sparse linear systems that arise from the discretization of the governing equations: (1) a preconditioner based on the incomplete LU (ILU) factorization, and (2) a recently-developed algebraic multigrid (AMG) preconditioner, constructed using the idea of semi-coarsening. A strong scalability study on a realistic, high resolution Greenland ice sheet problem reveals that, for a given number of processor cores, the AMG preconditionermore » results in faster linear solve times but the ILU preconditioner exhibits better scalability. In addition, a weak scalability study is performed on a realistic, moderate resolution Antarctic ice sheet problem, a substantial fraction of which contains floating ice shelves, making it fundamentally different from the Greenland ice sheet problem. We show that as the problem size increases, the performance of the ILU preconditioner deteriorates whereas the AMG preconditioner maintains scalability. This is because the linear systems are extremely ill-conditioned in the presence of floating ice shelves, and the ill-conditioning has a greater negative effect on the ILU preconditioner than on the AMG preconditioner.« less

Numerical simulations of debris drift from the Great Japan Tsunami of 2011 and their verification with observational reports.

PubMed

Maximenko, Nikolai; Hafner, Jan; Kamachi, Masafumi; MacFadyen, Amy

2018-05-02

A suite of five ocean models is used to simulate the movement of floating debris generated by the Great Japan Tsunami of 2011. This debris was subject to differential wind and wave-induced motion relative to the ambient current (often termed "windage") which is a function of the shape, size, and buoyancy of the individual debris items. Model solutions suggest that during the eastward drift across the North Pacific the debris became "stratified" by the wind so that objects with different windages took different paths: high windage items reached North America in large numbers the first year, medium windage items recirculated southwest toward Hawaii and Asia, and low windage items collected in the Subtropical Gyre, primarily in the so-called "garbage patch" area located northeast of Hawaii and known for high concentrations of microplastics. Numerous boats lost during the tsunami were later observed at sea and/or found on the west coast of North America: these observations are used to determine optimal windage values for scaling the model solutions. The initial number of boats set adrift during the tsunami is estimated at about 1000, while about 100 boats are projected to still float in year 2018 with an e-folding decay of 2 to 8 years. Copyright © 2018 Elsevier Ltd. All rights reserved.

How Does the Gibbs Inequality Condition Affect the Stability and Detachment of Floating Spheres from the Free Surface of Water?

PubMed

Feng, Dong-xia; Nguyen, Anh V

2016-03-01

Floating objects on the air-water interfaces are central to a number of everyday activities, from walking on water by insects to flotation separation of valuable minerals using air bubbles. The available theories show that a fine sphere can float if the force of surface tension and buoyancies can support the sphere at the interface with an apical angle subtended by the circle of contact being larger than the contact angle. Here we show that the pinning of the contact line at the sharp edge, known as the Gibbs inequality condition, also plays a significant role in controlling the stability and detachment of floating spheres. Specifically, we truncated the spheres with different angles and used a force sensor device to measure the force of pushing the truncated spheres from the interface into water. We also developed a theoretical modeling to calculate the pushing force that in combination with experimental results shows different effects of the Gibbs inequality condition on the stability and detachment of the spheres from the water surface. For small angles of truncation, the Gibbs inequality condition does not affect the sphere detachment, and hence the classical theories on the floatability of spheres are valid. For large truncated angles, the Gibbs inequality condition determines the tenacity of the particle-meniscus contact and the stability and detachment of floating spheres. In this case, the classical theories on the floatability of spheres are no longer valid. A critical truncated angle for the transition from the classical to the Gibbs inequality regimes of detachment was also established. The outcomes of this research advance our understanding of the behavior of floating objects, in particular, the flotation separation of valuable minerals, which often contain various sharp edges of their crystal faces.

Sink-float ferrofluid separator applicable to full scale nonferrous scrap separation

NASA Technical Reports Server (NTRS)

1973-01-01

Design and performance of a ferrofluid levitation separator for recovering nonferrous metals from shredded automobiles are reported. The scrap separator uses an electromagnet to generate a region of constant density within a pool of ferrofluid held between the magnetic poles; a saturated kerosene base ferrofluid as able to float all common industrial metals of interest. Conveyors move the scrap into the ferrofluid for separation according to density. Results of scrap mixture separation studies establish the technical feasibility of relatively pure aluminum alloy and zinc alloy fractions from shredded automobile scrap by this ferrofluid levitation process. Economic projections indicate profitable operation for shredders handling more than 300 cars per day.

Motivational Distortion on 16 PF Primaries by Male Felons.

ERIC Educational Resources Information Center

Wallbrown, Fred H.; And Others

1989-01-01

Investigated motivational distortion using the 16 Personality Factor Questionnaire (16 PF) for male (n=331) criminal offenders. Results indicated that ego-strength, free-floating anxiety, ability to bind anxiety, boldness, dominance, emotional sensitivity and suspiciousness contributed most to the motivational distortion scale predictions.…

Accessibility to primary health care in Belgium: an evaluation of policies awarding financial assistance in shortage areas.

PubMed

Dewulf, Bart; Neutens, Tijs; De Weerdt, Yves; Van de Weghe, Nico

2013-08-22

In many countries, financial assistance is awarded to physicians who settle in an area that is designated as a shortage area to prevent unequal accessibility to primary health care. Today, however, policy makers use fairly simple methods to define health care accessibility, with physician-to-population ratios (PPRs) within predefined administrative boundaries being overwhelmingly favoured. Our purpose is to verify whether these simple methods are accurate enough for adequately designating medical shortage areas and explore how these perform relative to more advanced GIS-based methods. Using a geographical information system (GIS), we conduct a nation-wide study of accessibility to primary care physicians in Belgium using four different methods: PPR, distance to closest physician, cumulative opportunity, and floating catchment area (FCA) methods. The official method used by policy makers in Belgium (calculating PPR per physician zone) offers only a crude representation of health care accessibility, especially because large contiguous areas (physician zones) are considered. We found substantial differences in the number and spatial distribution of medical shortage areas when applying different methods. The assessment of spatial health care accessibility and concomitant policy initiatives are affected by and dependent on the methodology used. The major disadvantage of PPR methods is its aggregated approach, masking subtle local variations. Some simple GIS methods overcome this issue, but have limitations in terms of conceptualisation of physician interaction and distance decay. Conceptually, the enhanced 2-step floating catchment area (E2SFCA) method, an advanced FCA method, was found to be most appropriate for supporting areal health care policies, since this method is able to calculate accessibility at a small scale (e.g., census tracts), takes interaction between physicians into account, and considers distance decay. While at present in health care research methodological differences and modifiable areal unit problems have remained largely overlooked, this manuscript shows that these aspects have a significant influence on the insights obtained. Hence, it is important for policy makers to ascertain to what extent their policy evaluations hold under different scales of analysis and when different methods are used.

Accessibility to primary health care in Belgium: an evaluation of policies awarding financial assistance in shortage areas

PubMed Central

2013-01-01

Background In many countries, financial assistance is awarded to physicians who settle in an area that is designated as a shortage area to prevent unequal accessibility to primary health care. Today, however, policy makers use fairly simple methods to define health care accessibility, with physician-to-population ratios (PPRs) within predefined administrative boundaries being overwhelmingly favoured. Our purpose is to verify whether these simple methods are accurate enough for adequately designating medical shortage areas and explore how these perform relative to more advanced GIS-based methods. Methods Using a geographical information system (GIS), we conduct a nation-wide study of accessibility to primary care physicians in Belgium using four different methods: PPR, distance to closest physician, cumulative opportunity, and floating catchment area (FCA) methods. Results The official method used by policy makers in Belgium (calculating PPR per physician zone) offers only a crude representation of health care accessibility, especially because large contiguous areas (physician zones) are considered. We found substantial differences in the number and spatial distribution of medical shortage areas when applying different methods. Conclusions The assessment of spatial health care accessibility and concomitant policy initiatives are affected by and dependent on the methodology used. The major disadvantage of PPR methods is its aggregated approach, masking subtle local variations. Some simple GIS methods overcome this issue, but have limitations in terms of conceptualisation of physician interaction and distance decay. Conceptually, the enhanced 2-step floating catchment area (E2SFCA) method, an advanced FCA method, was found to be most appropriate for supporting areal health care policies, since this method is able to calculate accessibility at a small scale (e.g. census tracts), takes interaction between physicians into account, and considers distance decay. While at present in health care research methodological differences and modifiable areal unit problems have remained largely overlooked, this manuscript shows that these aspects have a significant influence on the insights obtained. Hence, it is important for policy makers to ascertain to what extent their policy evaluations hold under different scales of analysis and when different methods are used. PMID:23964751

[The effect of floating-needle therapy combined with rehabilitation training for the hand function recovery of post-stroke patients].

PubMed

Yang, Jiangxia; Xiao, Hong

2015-08-01

To explore the improvement of hand motion function,spasm and self-care ability of daily life for stroke patients treated with floating-needle combined with rehabilitation training. Eighty hand spasm patients of post-stroke within one year after stroke were randomly divided into an observation group and a control group, 40 cases in each one. In the two groups, rehabilitation was adopted for eight weeks,once a day,40 min one time. In the observation group, based on the above treatment and according to muscle fascia trigger point, 2~3 points in both the internal and external sides of forearm were treated with floating-needle. The positive or passive flexion and extension of wrist and knuckle till the relief of spasm hand was combined. The floating-needle therapy was given for eight weeks, on the first three days once a day and later once every other day. Modified Ashworth Scale(MAS), activity of daily life(ADL, Barthel index) scores and Fugl-Meyer(FMA) scores were used to assess the spasm hand degree,activity of daily life and hand motion function before and after 7-day, 14-day and 8-week treatment. After 7-day, 14-day and 8-week treatment, MAS scores were apparently lower than those before treatment in the two groups(all P<0. 05), and Barthel scores and FMA scores were obviously higher than those before-treatment(all P<0. 05). After 14-day and 8-week treatment, FMA scores in the observation group were markedly higher than those in the control group(both P<0. 05). Floating-needle therapy combined with rehabilitation training and simple rehabilitation training could both improve hand spasm degree, hand function and activity of daily life of post-stroke patients, but floating-needle therapy combined with rehabilitation training is superior to simple rehabilitation training for the improvement of hand function.

Low-cost floating emergence net and bottle trap: Comparison of two designs

USGS Publications Warehouse

Cadmus, Pete; Pomeranz, Justin; Kraus, Johanna M.

2016-01-01

Sampling emergent aquatic insects is of interest to many freshwater ecologists. Many quantitative emergence traps require the use of aspiration for collection. However, aspiration is infeasible in studies with large amounts of replication that is often required in large biomonitoring projects. We designed an economic, collapsible pyramid-shaped floating emergence trap with an external collection bottle that avoids the need for aspiration. This design was compared experimentally to a design of similar dimensions that relied on aspiration to ensure comparable results. The pyramid-shaped design captured twice as many total emerging insects. When a preservative was used in bottle collectors, >95% of the emergent abundance was collected in the bottle. When no preservative was used, >81% of the total insects were collected from the bottle. In addition to capturing fewer emergent insects, the traps that required aspiration took significantly longer to sample. Large studies and studies sampling remote locations could benefit from the economical construction, speed of sampling, and capture efficiency.

Scalable NIC-based reduction on large-scale clusters

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

Moody, A.; Fernández, J. C.; Petrini, F.

2003-01-01

Many parallel algorithms require effiaent support for reduction mllectives. Over the years, researchers have developed optimal reduction algonduns by taking inm account system size, dam size, and complexities of reduction operations. However, all of these algorithm have assumed the faa that the reduction precessing takes place on the host CPU. Modem Network Interface Cards (NICs) sport programmable processors with substantial memory and thus introduce a fresh variable into the equation This raises the following intersting challenge: Can we take advantage of modern NICs to implementJost redudion operations? In this paper, we take on this challenge in the context of large-scalemore » clusters. Through experiments on the 960-node, 1920-processor or ASCI Linux Cluster (ALC) located at the Lawrence Livermore National Laboratory, we show that NIC-based reductions indeed perform with reduced latency and immed consistency over host-based aleorithms for the wmmon case and that these benefits scale as the system grows. In the largest configuration tested--1812 processors-- our NIC-based algorithm can sum a single element vector in 73 ps with 32-bi integers and in 118 with Mbit floating-point numnbers. These results represent an improvement, respeaively, of 121% and 39% with resvect w the {approx}roductionle vel MPI library« less

Ice shelf fracture parameterization in an ice sheet model

NASA Astrophysics Data System (ADS)

Sun, Sainan; Cornford, Stephen L.; Moore, John C.; Gladstone, Rupert; Zhao, Liyun

2017-11-01

Floating ice shelves exert a stabilizing force onto the inland ice sheet. However, this buttressing effect is diminished by the fracture process, which on large scales effectively softens the ice, accelerating its flow, increasing calving, and potentially leading to ice shelf breakup. We add a continuum damage model (CDM) to the BISICLES ice sheet model, which is intended to model the localized opening of crevasses under stress, the transport of those crevasses through the ice sheet, and the coupling between crevasse depth and the ice flow field and to carry out idealized numerical experiments examining the broad impact on large-scale ice sheet and shelf dynamics. In each case we see a complex pattern of damage evolve over time, with an eventual loss of buttressing approximately equivalent to halving the thickness of the ice shelf. We find that it is possible to achieve a similar ice flow pattern using a simple rule of thumb: introducing an enhancement factor ˜ 10 everywhere in the model domain. However, spatially varying damage (or equivalently, enhancement factor) fields set at the start of prognostic calculations to match velocity observations, as is widely done in ice sheet simulations, ought to evolve in time, or grounding line retreat can be slowed by an order of magnitude.

Large scale structures in a turbulent boundary layer and their imprint on wall shear stress

NASA Astrophysics Data System (ADS)

Pabon, Rommel; Barnard, Casey; Ukeiley, Lawrence; Sheplak, Mark

2015-11-01

Experiments were performed on a turbulent boundary layer developing on a flat plate model under zero pressure gradient flow. A MEMS differential capacitive shear stress sensor with a 1 mm × 1 mm floating element was used to capture the fluctuating wall shear stress simultaneously with streamwise velocity measurements from a hot-wire anemometer traversed in the wall normal direction. Near the wall, the peak in the cross correlation corresponds to an organized motion inclined 45° from the wall. In the outer region, the peak diminishes in value, but is still significant at a distance greater than half the boundary layer thickness, and corresponds to a structure inclined 14° from the wall. High coherence between the two signals was found for the low-frequency content, reinforcing the belief that large scale structures have a vital impact on wall shear stress. Thus, estimation of the wall shear stress from the low-frequency velocity signal will be performed, and is expected to be statistically significant in the outer boundary layer. Additionally, conditionally averaged mean velocity profiles will be presented to assess the effects of high and low shear stress. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138.

Predicting the buoyancy, equilibrium and potential swimming ability of giraffes by computational analysis.

PubMed

Henderson, Donald M; Naish, Darren

2010-07-21

Giraffes (Giraffa camelopardalis) are often stated to be unable to swim, and while few observations supporting this have ever been offered, we sought to test the hypothesis that giraffes exhibited a body shape or density unsuited for locomotion in water. We assessed the floating capability of giraffes by simulating their buoyancy with a three-dimensional mathematical/computational model. A similar model of a horse (Equus caballus) was used as a control, and its floating behaviour replicates the observed orientations of immersed horses. The floating giraffe model has its neck sub-horizontal, and the animal would struggle to keep its head clear of the water surface. Using an isometrically scaled-down giraffe model with a total mass equal to that of the horse, the giraffe's proportionally larger limbs have much higher rotational inertias than do those of horses, and their wetted surface areas are 13.5% greater relative to that of the horse, thus making rapid swimming motions more strenuous. The mean density of the giraffe model (960 gm/l) is also higher than that of the horse (930 gm/l), and closer to that causing negative buoyancy (1000 gm/l). A swimming giraffe - forced into a posture where the neck is sub-horizontal and with a thorax that is pulled downwards by the large fore limbs - would not be able to move the neck and limbs synchronously as giraffes do when moving on land, possibly further hampering the animal's ability to move its limbs effectively underwater. We found that a full-sized, adult giraffe will become buoyant in water deeper than 2.8m. While it is not impossible for giraffes to swim, we speculate that they would perform poorly compared to other mammals and are hence likely to avoid swimming if possible. (c) 2010. Published by Elsevier Ltd. All rights reserved.

rpe v5: an emulator for reduced floating-point precision in large numerical simulations

NASA Astrophysics Data System (ADS)

Dawson, Andrew; Düben, Peter D.

2017-06-01

This paper describes the rpe (reduced-precision emulator) library which has the capability to emulate the use of arbitrary reduced floating-point precision within large numerical models written in Fortran. The rpe software allows model developers to test how reduced floating-point precision affects the result of their simulations without having to make extensive code changes or port the model onto specialized hardware. The software can be used to identify parts of a program that are problematic for numerical precision and to guide changes to the program to allow a stronger reduction in precision.The development of rpe was motivated by the strong demand for more computing power. If numerical precision can be reduced for an application under consideration while still achieving results of acceptable quality, computational cost can be reduced, since a reduction in numerical precision may allow an increase in performance or a reduction in power consumption. For simulations with weather and climate models, savings due to a reduction in precision could be reinvested to allow model simulations at higher spatial resolution or complexity, or to increase the number of ensemble members to improve predictions. rpe was developed with a particular focus on the community of weather and climate modelling, but the software could be used with numerical simulations from other domains.

Dynamic response signatures of a scaled model platform for floating wind turbines in an ocean wave basin.

PubMed

Jaksic, V; O'Shea, R; Cahill, P; Murphy, J; Mandic, D P; Pakrashi, V

2015-02-28

Understanding of dynamic behaviour of offshore wind floating substructures is extremely important in relation to design, operation, maintenance and management of floating wind farms. This paper presents assessment of nonlinear signatures of dynamic responses of a scaled tension-leg platform (TLP) in a wave tank exposed to different regular wave conditions and sea states characterized by the Bretschneider, the Pierson-Moskowitz and the JONSWAP spectra. Dynamic responses of the TLP were monitored at different locations using load cells, a camera-based motion recognition system and a laser Doppler vibrometer. The analysis of variability of the TLP responses and statistical quantification of their linearity or nonlinearity, as non-destructive means of structural monitoring from the output-only condition, remains a challenging problem. In this study, the delay vector variance (DVV) method is used to statistically study the degree of nonlinearity of measured response signals from a TLP. DVV is observed to create a marker estimating the degree to which a change in signal nonlinearity reflects real-time behaviour of the structure and also to establish the sensitivity of the instruments employed to these changes. The findings can be helpful in establishing monitoring strategies and control strategies for undesirable levels or types of dynamic response and can help to better estimate changes in system characteristics over the life cycle of the structure. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

DETECTABILITY OF FREE FLOATING PLANETS IN OPEN CLUSTERS WITH THE JAMES WEBB SPACE TELESCOPE

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

Pacucci, Fabio; Ferrara, Andrea; D'Onghia, Elena

Recent observations have shown the presence of extra-solar planets in Galactic open stellar clusters, such as in Praesepe (M44). These systems provide a favorable environment for planetary formation due to the high heavy-element content exhibited by the majority of their population. The large stellar density, and corresponding high close-encounter event rate, may induce strong perturbations of planetary orbits with large semimajor axes. Here we present a set of N-body simulations implementing a novel scheme to treat the tidal effects of external stellar perturbers on planetary orbit eccentricity and inclination. By simulating five nearby open clusters, we determine the rate ofmore » occurrence of bodies extracted from their parent stellar system by quasi-impulsive tidal interactions. We find that the specific free-floating planet production rate N-dot {sub o} (total number of free-floating planets per unit of time, normalized by the total number of stars), is proportional to the stellar density ρ{sub *} of the cluster: N-dot {sub o}=αρ{sub ⋆}, with α = (23 ± 5) × 10{sup –6} pc{sup 3} Myr{sup –1}. For the Pleiades (M45), we predict that ∼26% of stars should have lost their planets. This raises the exciting possibility of directly observing these wandering planets with the James Webb Space Telescope in the near-infrared band. Assuming a surface temperature for the planet of ∼500 K, a free-floating planet of Jupiter size inside the Pleiades would have a specific flux of F {sub ν} (4.4 μm) ≈4 × 10{sup 2} nJy, which would lead to a very clear detection (S/N ∼ 100) in only one hour of integration.« less

Correlation of ISS Electric Potential Variations with Mission Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda Neergaard

2014-01-01

Orbiting approximately 400 km above the Earth, the International Space Station (ISS) is a unique research laboratory used to conduct ground-breaking science experiments in space. The ISS has eight Solar Array Wings (SAW), and each wing is 11.7 meters wide and 35.1 meters long. The SAWs are controlled individually to maximize power output, minimize stress to the ISS structure, and minimize interference with other ISS operations such as vehicle dockings and Extra-Vehicular Activities (EVA). The Solar Arrays are designed to operate at 160 Volts. These large, high power solar arrays are negatively grounded to the ISS and collect charged particles (predominately electrons) as they travel through the space plasma in the Earth's ionosphere. If not controlled, this collected charge causes floating potential variations which can result in arcing, causing injury to the crew during an EVA or damage to hardware [1]. The environmental catalysts for ISS floating potential variations include plasma density and temperature fluctuations and magnetic induction from the Earth's magnetic field. These alone are not enough to cause concern for ISS, but when they are coupled with the large positive potential on the solar arrays, floating potentials up to negative 95 Volts have been observed. Our goal is to differentiate the operationally induced fluctuations in floating potentials from the environmental causes. Differentiating will help to determine what charging can be controlled, and we can then design the proper operations controls for charge collection mitigation. Additionally, the knowledge of how high power solar arrays interact with the environment and what regulations or design techniques can be employed to minimize charging impacts can be applied to future programs.

Impact Experiments into Borosilicate Glass at Three Scale Sizes

DTIC Science & Technology

2009-11-01

DEDF and soda - lime glass during rod impact. Shock Compression in Condensed Matter–2005 (Furnish MD, Elert M, Russell TP, and White CT, Eds.) AIP Conf...in a float soda - lime silicate glass . Int. J. Appl. Glass Sci., to be submitted (2009). 18. Chocron S, Dannemann KA, Nicholls AE, and Anderson CE Jr...UNCLASSIFIED UNCLASSIFIED Impact Experiments into Borosilicate Glass at Three Scale Sizes Charles E. Anderson, Jr. Carl E. Weiss Sidney Chocron

Buttressing and stability of marine Ice sheets

NASA Astrophysics Data System (ADS)

Goldberg, D.; Holland, D. M.; Schoof, C.

2009-04-01

The West Antarctic Ice Sheet is marine in nature, meaning most of its base is below sea level. At the grounding line (where it becomes thin enough to float), its outlet streams flow into large ice shelves. Gravitational stress in the shelf is transmitted back to the grounding line, and largely balanced by basal friction in the transition zone. The details of this force balance control the evolution of both the thickness and grounded extent of the ice sheet, and can lead to Weertman's (1974) Marine Instability for a foredeepened bedrock (one that deepens inland). However, the presence of rigid sidewalls and locally grounded regions in the shelf can reduce the longitudinal stresses felt at the grounding line (a phenomenon called buttressing). Thomas (1979) and others pointed out that Marine Instability may be lessened or reversed by ice shelf buttressing. When modelling marine ice sheets numerically, the physics of the grounded-to-floating transition must be represented and the associated small length scales must be resolved (Schoof, 2007). Failing to do so can result in nonphysical or numerically inconsistent behavior (Vieli and Payne, 2005). While several methods have been developed to treat these issues (Vieli and Payne, 2005; Pattyn et al, 2006; Schoof, 2007) they are limited to flowline models. We present a model that represents the physics of the grounded-to-floating transition in a time-dependent three-dimensional marine ice sheet, using mesh adaption to resolve the transition zone. We show that in the special case of a two-dimensional sheet our model reproduces the theoretical results of the MISMIP experiments, and that it produces robust results when both horizontal dimensions are resolved. In idealized experiments in a channel with rigid sidewalls and a foredeepened bed, we narrow the channel to determine whether buttressing is sufficient to reverse instability. We find that for strong beds (high friction coefficients), while the timescales and dynamics are affected greatly by buttressing, true stability reversal is still not seen even as the channel becomes quite narrow. However, for weaker beds, stability is seen, though it can be shown that sufficient ocean melting can still cause collapse. Experiments with more complicated bed topography show that locally grounded areas (ice rises) have similar dynamic effects to rigid sidewalls.

Quality of life and educational benefit among orthopedic surgery residents: a prospective, multicentre comparison of the night float and the standard call systems

PubMed Central

Zahrai, Ali; Chahal, Jaskarndip; Stojimirovic, Dan; Schemitsch, Emil H.; Yee, Albert; Kraemer, William

2011-01-01

Background Given recent evolving guidelines regarding postcall clinical relief of residents and emphasis on quality of life, novel strategies are required for implementing call schedules. The night float system has been used by some institutions as a strategy to decrease the burden of call on resident quality of life in level-1 trauma centres. The purpose of this study was to determine whether there are differences in quality of life, work-related stressors and educational experience between orthopedic surgery residents in the night float and standard call systems at 2 level-1 trauma centres. Methods We conducted a prospective cohort study at 2 level-1 trauma hospitals comprising a standard call (1 night in 4) group and a night float (5 14-hour shifts [5 pm–7 am] from Monday to Friday) group for each hospital. Over the course of a 6-month rotation, each resident completed 3 weeks of night float. The remainder of the time on the trauma service consists of clinical duties from 6:30 am to 5:30 pm on a daily basis and intermittent coverage of weekend call only. Residents completed the Short Form-36 (SF-36) general quality-of-life questionnaire, as well as questionnaires on stress level and educational experience before the rotation (baseline) and at 2, 4 and 6 months. We performed an analysis of covariance to compare between-group differences using the baseline scores as covariates and Wilcoxon signed-rank tests (nonparametric) to determine if the residents’ SF-36 scores were different from the age- and sex-matched Canadian norms. We analyzed predictors of resident quality of life using multivariable mixed models. Results Seven residents were in the standard call group and 9 in the night float group, for a total of 16 residents (all men, mean age 35.1 yr). Controlling for between-group differences at baseline, residents on the night float rotation had significantly lower role physical, bodily pain, social function and physical component scale scores over the 6-month observation period. Compared with the Canadian normative population, the night float group had significantly lower SF-36 scores in all subscales except for bodily pain. There were no differences noted between the standard call group and Canadian norms at 6 months. No differences in educational benefits and stress level were measured between the 2 groups. Lack of time for physical activity was only significant in the night float group. Regression analysis demonstrated that the increased number of hours in hospital correlated with significantly lower SF-36 scores in almost all domains. Conclusion Our study suggests that the residents in the standard call group had better health-related quality of life compared with those in the night float group. No differences existed in subjective educational benefits and stress level between the groups. PMID:21251429

Quality of life and educational benefit among orthopedic surgery residents: a prospective, multicentre comparison of the night float and the standard call systems.

PubMed

Zahrai, Ali; Chahal, Jaskarndip; Stojimirovic, Dan; Schemitsch, Emil H; Yee, Albert; Kraemer, William

2011-02-01

Given recent evolving guidelines regarding postcall clinical relief of residents and emphasis on quality of life, novel strategies are required for implementing call schedules. The night float system has been used by some institutions as a strategy to decrease the burden of call on resident quality of life in level-1 trauma centres. The purpose of this study was to determine whether there are differences in quality of life, work-related stressors and educational experience between orthopedic surgery residents in the night float and standard call systems at 2 level-1 trauma centres. We conducted a prospective cohort study at 2 level-1 trauma hospitals comprising a standard call (1 night in 4) group and a night float (5 14-hour shifts [5 pm-7 am] from Monday to Friday) group for each hospital. Over the course of a 6-month rotation, each resident completed 3 weeks of night float. The remainder of the time on the trauma service consists of clinical duties from 6:30 am to 5:30 pm on a daily basis and intermittent coverage of weekend call only. Residents completed the Short Form-36 (SF-36) general quality-of-life questionnaire, as well as questionnaires on stress level and educational experience before the rotation (baseline) and at 2, 4 and 6 months. We performed an analysis of covariance to compare between-group differences using the baseline scores as covariates and Wilcoxon signed-rank tests (nonparametric) to determine if the residents' SF-36 scores were different from the age- and sex-matched Canadian norms. We analyzed predictors of resident quality of life using multivariable mixed models. Seven residents were in the standard call group and 9 in the night float group, for a total of 16 residents (all men, mean age 35.1 yr). Controlling for between-group differences at baseline, residents on the night float rotation had significantly lower role physical, bodily pain, social function and physical component scale scores over the 6-month observation period. Compared with the Canadian normative population, the night float group had significantly lower SF-36 scores in all subscales except for bodily pain. There were no differences noted between the standard call group and Canadian norms at 6 months. No differences in educational benefits and stress level were measured between the 2 groups. Lack of time for physical activity was only significant in the night float group. Regression analysis demonstrated that the increased number of hours in hospital correlated with significantly lower SF-36 scores in almost all domains. Our study suggests that the residents in the standard call group had better health-related quality of life compared with those in the night float group. No differences existed in subjective educational benefits and stress level between the groups.

Shifting balance of thermokarst lake ice regimes across the Arctic Coastal Plain of northern Alaska

USGS Publications Warehouse

Arp, Christopher D.; Jones, Benjamin M.; Lu, Zong; Whitman, Matthew S.

2012-01-01

The balance of thermokarst lakes with bedfast- and floating-ice regimes across Arctic lowlands regulates heat storage, permafrost thaw, winter-water supply, and over-wintering aquatic habitat. Using a time-series of late-winter synthetic aperture radar (SAR) imagery to distinguish lake ice regimes in two regions of the Arctic Coastal Plain of northern Alaska from 2003–2011, we found that 18% of the lakes had intermittent ice regimes, varying between bedfast-ice and floating-ice conditions. Comparing this dataset with a radar-based lake classification from 1980 showed that 16% of the bedfast-ice lakes had shifted to floating-ice regimes. A simulated lake ice thinning trend of 1.5 cm/yr since 1978 is believed to be the primary factor driving this form of lake change. The most profound impacts of this regime shift in Arctic lakes may be an increase in the landscape-scale thermal offset created by additional lake heat storage and its role in talik development in otherwise continuous permafrost as well as increases in over-winter aquatic habitat and winter-water supply.

Stabilizing canonical-ensemble calculations in the auxiliary-field Monte Carlo method

NASA Astrophysics Data System (ADS)

Gilbreth, C. N.; Alhassid, Y.

2015-03-01

Quantum Monte Carlo methods are powerful techniques for studying strongly interacting Fermi systems. However, implementing these methods on computers with finite-precision arithmetic requires careful attention to numerical stability. In the auxiliary-field Monte Carlo (AFMC) method, low-temperature or large-model-space calculations require numerically stabilized matrix multiplication. When adapting methods used in the grand-canonical ensemble to the canonical ensemble of fixed particle number, the numerical stabilization increases the number of required floating-point operations for computing observables by a factor of the size of the single-particle model space, and thus can greatly limit the systems that can be studied. We describe an improved method for stabilizing canonical-ensemble calculations in AFMC that exhibits better scaling, and present numerical tests that demonstrate the accuracy and improved performance of the method.

Wave energy absorption by a floating air bag

NASA Astrophysics Data System (ADS)

Kurniawan, A.; Chaplin, J. R.; Greaves, D. M.; Hann, M.

2017-02-01

A floating air bag, ballasted in water, expands and contracts as it heaves under wave action. Connecting the bag to a secondary volume via a turbine transforms the bag into a device capable of generating useful energy from the waves. Small-scale measurements of the device reveal some interesting properties, which are successfully predicted numerically. Owing to its compressibility, the device can have a heave resonance period longer than that of a rigid device of the same shape and size, without any phase control. Furthermore, varying the amount of air in the bag is found to change its shape and hence its dynamic response, while varying the turbine damping or the air volume ratio changes the dynamic response without changing the shape.

Biogeochemical sensor performance in the SOCCOM profiling float array

NASA Astrophysics Data System (ADS)

Johnson, Kenneth S.; Plant, Joshua N.; Coletti, Luke J.; Jannasch, Hans W.; Sakamoto, Carole M.; Riser, Stephen C.; Swift, Dana D.; Williams, Nancy L.; Boss, Emmanuel; Haëntjens, Nils; Talley, Lynne D.; Sarmiento, Jorge L.

2017-08-01

The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program has begun deploying a large array of biogeochemical sensors on profiling floats in the Southern Ocean. As of February 2016, 86 floats have been deployed. Here the focus is on 56 floats with quality-controlled and adjusted data that have been in the water at least 6 months. The floats carry oxygen, nitrate, pH, chlorophyll fluorescence, and optical backscatter sensors. The raw data generated by these sensors can suffer from inaccurate initial calibrations and from sensor drift over time. Procedures to correct the data are defined. The initial accuracy of the adjusted concentrations is assessed by comparing the corrected data to laboratory measurements made on samples collected by a hydrographic cast with a rosette sampler at the float deployment station. The long-term accuracy of the corrected data is compared to the GLODAPv2 data set whenever a float made a profile within 20 km of a GLODAPv2 station. Based on these assessments, the fleet average oxygen data are accurate to 1 ± 1%, nitrate to within 0.5 ± 0.5 µmol kg-1, and pH to 0.005 ± 0.007, where the error limit is 1 standard deviation of the fleet data. The bio-optical measurements of chlorophyll fluorescence and optical backscatter are used to estimate chlorophyll a and particulate organic carbon concentration. The particulate organic carbon concentrations inferred from optical backscatter appear accurate to with 35 mg C m-3 or 20%, whichever is larger. Factors affecting the accuracy of the estimated chlorophyll a concentrations are evaluated.