Note: This page contains sample records for the topic high gravity levels from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Preprocessing of gravity gradients at the GOCE high-level processing facility  

NASA Astrophysics Data System (ADS)

One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in Earth scienes and gravity field analysis, additional preprocessing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and nontidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/ f behaviour for low frequencies. In the outlier detection, the 1/ f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/ f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low-degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10-3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10-2 level with this method.

Bouman, Johannes; Rispens, Sietse; Gruber, Thomas; Koop, Radboud; Schrama, Ernst; Visser, Pieter; Tscherning, Carl Christian; Veicherts, Martin

2009-07-01

2

Groundwater level monitoring using hybrid gravity measurements  

NASA Astrophysics Data System (ADS)

It is important to monitor the aquifer mass balance between discharge and recharge for the sustainable groundwater usage. The discharge of groundwater causes mass redistributions, which can cause measurable gravity changes. We carried out the repeat hybrid gravity measurements at some fields in order to detect the gravity changes associated with groundwater level changes. We used the instruments for the relative gravity measurement (CG-3M and CG-5 gravimeter: Scintrex Ltd.) and the absolute gravity measurement (A-10 gravimeter: Micro-g LaCoste, Inc.). The A10 absolute gravimeter is a portable absolute gravimeter produced by Micro-g LaCoste Inc. It operates on a 12V DC power supply (i.e. vehicle battery). We can measure the absolute gravity using the vehicle battery at the field. We started repeat gravity measurement at Ito campus, Kyushu university Fukuoka city, Northern part of Kyushu, Japan, where the instrument is usually maintained, since 2008 in order to assess the A10 gravimeter's accuracy and repeatability. We measured 10 sets at each measurement, and 1 set consists of 100 drops. There are 3 groundwater level monitoring wells near the gravity station. It can be seen that there is a good correlation between gravity changes and groundwater level changes. We confirmed that the instrument is maintained good condition in general, although some bad data was included. It seems that the repeatability of A10 gravimeter is better than 10 microgals. The A10 absolute gravimeter (Micro-g LaCoste Inc.) was introduced in order to monitor the gravity changes at base observation points since 2008. We observed seasonal gravity change (Maximum change was 26 micro gal), and we compared with the groundwater level changes. There are good correlation between the gravity changes and the groundwater level changes. We calculated the effect of groundwater level changes using Gwater-1D (Kazama et al., 2010). As a result of the calculation, we can explain the gravity seasonal changes were caused by the groundwater level changes. The gravity changes of the base observation were removed from each observation point. We can see the good correlation between the gravity changes and the groundwater level change in the almost observation point. The effect of the construction of the campus awaits future studies.

Nishijima, J.; Fujimitsu, Y.; Oka, D.; Fukuda, Y.; Taniguchi, M.

2012-12-01

3

High-precision gravity network to monitor temporal variations in gravity across Yucca Mountain, Nevada  

SciTech Connect

Repeatable high-precision gravity surveys provide a method of monitoring temporal variations in the gravity field. Fluctuations in the gravity field may indicate water table changes, crustal deformation, or precursors to volcanism and earthquakes. This report describes a high-precision gravity loop which has been established across Yucca Mountain, Nevada in support of the Nevada Nuclear Waste Storage Investigations (NNWSI) program. The purpose of this gravity loop is to monitor temporal variations in gravity across Yucca Mountain in an effort to interpret and predict the stability of the tectonic framework and changes in the subsurface density field. Studies of the tectonic framework which include volcanic hazard seismicity, and faulting studies are in progress. Repeat high-precision gravity surveys are less expensive and can be made more rapidly than a corresponding leveling survey. High-precision gravity surveys are capable of detecting elevation changes of 3 to 5 cm, and thus can be employed as an efficient tool for monitoring vertical crustal movements while supplementing or partially replacing leveling data. The Yucca Mountain gravity network has been tied to absolute gravity measurements established in southern Nevada. These ties provide an absolute datum for comparing repeat occupations of the gravity network, and provide a method of monitoring broad-scale changes in gravity. Absolute gravity measurements were also made at the bottom and top of the Charleston Peak calibration loop in southern Nevada. These absolute gravity measurements provide local control of calibrating gravity meters over the gravity ranges observed at Yucca Mountain. 13 refs., 7 figs., 3 tabs.

Harris, R.N.; Ponce, D.A.

1988-12-31

4

Creeping granular motion under variable gravity levels.  

PubMed

In a rotating tumbler that is more than one-half filled with a granular material, a core of material forms that should ideally rotate with the tumbler. However, the core rotates slightly faster than the tumbler (precession) and decreases in size (erosion). The precession and erosion of the core provide a measure of the creeping granular motion that occurs beneath a continuously flowing flat surface layer. Since the effect of gravity on the subsurface flow has not been explored, experiments were performed in a 63% to 83% full granular tumbler mounted in a large centrifuge that can provide very high g-levels. Two colors of 0.5 mm glass beads were filled side by side to mark a vertical line in the 45 mm radius quasi-two-dimensional tumbler. The rotation of the core with respect to the tumbler (precession) and the decrease in the size of the core (erosion) were monitored over 250 tumbler revolutions at accelerations between 1g and 12g. The flowing layer thickness is essentially independent of the g-level for identical Froude numbers, and the shear rate in the flowing layer increases with increasing g-level. The degree of core precession increases with the g-level, while the core erosion is essentially independent of the g-level. Based on a theory for core precession and erosion, the increased precession is likely a consequence of the higher shear rate. Core erosion, on the other hand, is related to the creep region decay constant, which is connected with slow diffusion in the bed and unaffected by gravity. PMID:17025623

Arndt, Tim; Brucks, Antje; Ottino, Julio M; Lueptow, Richard M

2006-09-01

5

The Constant Levelers: Water, Ice, and Gravity  

NSDL National Science Digital Library

This site has information about the work of three of the agents of erosion in the Northern Cascade Range. Since much of the range is made up of exotic terrains that probably did not evolve on the same spot on the Earth as the present North Cascades, the geologists confine their view to some time since the earliest Tertiary. Within that time frame, they can speculatively recreate the North Cascade scene and ponder its erosional history. The erosional work of rivers has constantly been altered by volcanic activity and whatever drainage pattern was established. It was profoundly altered about 35 million years ago by the renewed volcanic activity of the Cascade Volcanic Arc. A section about how rivers erode describes differential erosion, stream capture, and base level. The section about glaciers explains how they are formed, how they do their work, and what is left behind. The section about the work of gravity focuses on creep and landslides.

6

Viscous Stabilization of Gravity Wave Critical Level Flows  

Microsoft Academic Search

A criterion for the viscous stabilization of gravity wave critical level flow is derived to be Z 1\\/4 2.5 Zr where Z 1\\/4 is the vertical thickness of the unstable region in the vicinity of a gravity wave critical level calculated with an inviscid linear theory and Zy is the viscous length scale for gravity wave critical level interaction. The

David C. Fritts; Marvin A. Geller

1976-01-01

7

High-Resolution Gravity and Time-Varying Gravity Field Recovery using GRACE and CHAMP  

NASA Technical Reports Server (NTRS)

This progress report summarizes the research work conducted under NASA's Solid Earth and Natural Hazards Program 1998 (SENH98) entitled High Resolution Gravity and Time Varying Gravity Field Recovery Using GRACE (Gravity Recovery and Climate Experiment) and CHAMP (Challenging Mini-satellite Package for Geophysical Research and Applications), which included a no-cost extension time period. The investigation has conducted pilot studies to use the simulated GRACE and CHAMP data and other in situ and space geodetic observable, satellite altimeter data, and ocean mass variation data to study the dynamic processes of the Earth which affect climate change. Results from this investigation include: (1) a new method to use the energy approach for expressing gravity mission data as in situ measurements with the possibility to enhance the spatial resolution of the gravity signal; (2) the method was tested using CHAMP and validated with the development of a mean gravity field model using CHAMP data, (3) elaborate simulation to quantify errors of tides and atmosphere and to recover hydrological and oceanic signals using GRACE, results show that there are significant aliasing effect and errors being amplified in the GRACE resonant geopotential and it is not trivial to remove these errors, and (4) quantification of oceanic and ice sheet mass changes in a geophysical constraint study to assess their contributions to global sea level change, while the results improved significant over the use of previous studies using only the SLR (Satellite Laser Ranging)-determined zonal gravity change data, the constraint could be further improved with additional information on mantle rheology, PGR (Post-Glacial Rebound) and ice loading history. A list of relevant presentations and publications is attached, along with a summary of the SENH investigation generated in 2000.

Shum, C. K.

2002-01-01

8

Arctic margin gravity highs remain puzzling  

Microsoft Academic Search

Many passive continental margins, particularly in the Arctic (Figures 1 and 2), are festooned by chains of elongate positive gravity anomalies overlying, in part, marginal oceanic crust. To this day, no simple unifying explanation has emerged to account for these highs. Variously modeled by mantle doming, crustal thinning, dense crust, basement rises, postbreakup sediment depocenters, and topographic effects, these anomalies

Peter R. Vogt; Woo-Yeol Jung; John Brozena

1998-01-01

9

The Gravity Model for High School Students  

ERIC Educational Resources Information Center

The authors suggest ways in which the gravity model can be used in high school geography classes. Based on Newton's Law of Molecular Gravitation, the law states that gravitation is in direct ratio to mass and inverse ratio to distance. One activity for students involves determination of zones of influence of cities of various sizes. (Author/AV)

Tribble, Paul; Mitchell, William A.

1977-01-01

10

Antarctic marine gravity field from high-density satellite altimetry  

NASA Technical Reports Server (NTRS)

High-density (about 2-km profile spacing) Geosat/GM altimetry profiles were obtained for Antarctic waters (6-deg S to 72 deg S) and converted to vertical gravity gradient, using Laplace's equation to directly calculate gravity gradient from vertical deflection grids and Fourier analysis to construct gravity anomalies from two vertical deflection grids. The resultant gravity grids have resolution and accuracy comparable to shipboard gravity profiles. The obtained gravity maps display many interesting and previously uncharted features, such as a propagating rift wake and a large 'leaky transform' along the Pacific-Antarctic Rise.

Sandwell, David T.

1992-01-01

11

Improved GOCE Gradiometer Level 1b Data Processing - Impact on Gravity Gradients and Gravity Field Models  

NASA Astrophysics Data System (ADS)

In the last year enhanced strategies for the GOCE gradiometer Level 1b processing have been developed, published and implemented within ESA's payload data ground segment. The novelties are (a) an improved method for the reconstruction of angular rates from gradiometer and star sensor data, (b) a new method for the determination of the inertial attitude quaternions, also based on a combination of gradiometer and star sensor data, (c) the use of all simultaneously available star sensor data and (d) an improved calibration of the gradiometer data that takes the time dependency of calibration parameters into account. At this point in time, the reprocessing of the gradiometer data is almost complete. In this paper, a quality assessment of the reprocessed gradiometer data is performed for two selected periods: 01/11/2009 - 31/12/2009 and 08/06/2011 - 23/08/2011. This allows on the one hand a comparison of the reprocessed and original (first released) data. The improved quality of reprocessed data is demonstrated on the level of gravity gradients as well as gravity field models. On the other hand, the analysis of the two periods allows a comparison of the quality of gravity gradients that were obtained under different aerodynamic drag conditions. Since the launch in 2009, aerodynamic drag experienced by the GOCE satellite has increased as the solar cycle advances towards maximum solar activity expected in 2013. In this way, the importance of the reprocessing is stressed not only for gradiometer data measured until today, but also in the future.

Siemes, C.; Stummer, C.; Fecher, T.; Rexer, M.; Haagmans, R.; Floberghagen, R.

2012-04-01

12

The role of new terrestrial gravity\\/GPS\\/levelling data, GRACE geopotential model and SRTM elevations on the earth gravity field modelling and its changes in Iran  

Microsoft Academic Search

In order to model the earth gravity field and its temporal variations, different gravity data with terrestrial, airborne and satellite gathered kinds are necessary. It is possible to recover by them the short, medium and long wavelengths of the gravity field respectively. Terrestrial gravity data, especially for the regions with highly variations, are useful for different purposes, i.e. to estimate

Yaghoub Hatam Chavari; Roger Bayer; Yahya Djamour; Petr Vanicek

2010-01-01

13

High potassium level  

MedlinePLUS

High potassium level is a problem in which the amount of potassium in the blood is higher than normal. The medical ... There are often no symptoms with a high level of potassium. When symptoms do occur, they may ...

14

Superalloy microstructural variations induced by gravity level during directional solidification  

NASA Technical Reports Server (NTRS)

The Ni-base superalloy MAR-M246 (Hf) was directionally solidified during low gravity maneuvers aboard a NASA KC-135 aircraft. Gravity force variations during this process yielded a concomitant variation in microstructure and microsegregation. Secondary dendrite arm spacings are noted to be larger in the low-g portion; this, in turn, decreases the extent of interdendritic segregation. The amount of Hf in both the carbides and interdendritic eutectic increases as the gravity force diminishes. Fewer carbides are present in the low-g regions.

Johnston, M. H.; Curreri, P. A.; Parr, R. A.; Alter, W. S.

1985-01-01

15

Calibration of GOCE SGG data using high–low SST, terrestrial gravity data and global gravity field models  

Microsoft Academic Search

It is the aim of the GOCE mission to determine a model of the Earth’s gravity field with high accuracy and resolution. For this purpose, gravity gradients will be measured in combination with high–low satellite-to-satellite tracking. The gravity gradients are derived from pair-wise differenced accelerations as determined by the six three-axes accelerometers that form the GOCE gradiometer. Since the measured

J. Bouman; R. Koop; C. C. Tscherning; P. Visser

2004-01-01

16

Study of In-situ Gravity Wave Sources at High Latitude using High-Resolution Model  

NASA Astrophysics Data System (ADS)

Gravity waves are one of the key elements for driving the atmospheric coupling from the stratosphere to the thermosphere. However, the knowledge of spatial and temporal variations of gravity wave sources is still limited, causing the uncertainties in gravity wave parameterization in general circulation models. In this study, we focus on the in-situ gravity wave excitation at high-latitude under the highly dynamic condition, such as stratospheric sudden warming (SSW) in 2009, using the high-resolution ECMWF-T799 model. ECMWF results indicate that gravity wave activities enhance at the edge of the polar jet prior to the 2009 SSW. The magnitude and occurrence of gravity waves correlate well with the location and strength of the polar vortex that is strongly distorted by planetary wave growth. Such increases of gravity wave activities correspond well with the increase of the residual tendencies that indicates the potential locations of in-situ gravity wave excitation. Gravity wave variations during the 2009 SSW are validated with the COSMIC/GPS observations. Finally, climatology of gravity waves resolved in the high-resolution ECMWF-T799 is compared with the ground-based lidar data at high-latitudes and global SABER observations to discuss the capabilities and limitations of the high-resolution ECMWF-T799 model.

Yamashita, C.; Liu, H.; Chu, X.

2012-12-01

17

Calibration of GOCE SGG data using high low SST, terrestrial gravity data and global gravity field models  

NASA Astrophysics Data System (ADS)

It is the aim of the GOCE mission to determine a model of the Earth’s gravity field with high accuracy and resolution. For this purpose, gravity gradients will be measured in combination with high low satellite-to-satellite tracking. The gravity gradients are derived from pair-wise differenced accelerations as determined by the six three-axes accelerometers that form the GOCE gradiometer. Since the measured accelerations suffer from errors of a random and systematic nature, the gravity gradients may suffer from random and systematic errors as well. Systematic errors are, for example, a scale factor and a bias. The common accelerations of the paired accelerometers also are contaminated with such errors. The common accelerations are used in the drag-free control of the satellite and are important for the separation of the gravitational and non-gravitational forces in the gravity field determination. The checking of the gravity gradients and the common accelerations against independent data (i.e. external to the GOCE satellite) in order to free the observations as well as is possible from systematic errors is called external calibration. The possibilities and limitations of using terrestrial gravity data and global gravity models for external calibration of the gravity gradients are reviewed. It turns out that the determination of a gravity gradient scale factor and bias using just the accurate knowledge of the central term and the flattening (J2) of the Earth’s gravity field is not good enough. When global gravity field models are used for the calibration, higher degrees and orders should be taken into account as well. With today’s existing global models it seems to be possible to remove the greater part of the systematic errors of the GOCE gradients. A gravity gradient bias can accurately be recovered using terrestrial gravity data in a regional approach with least squares collocation. However, since regional data are used it may not be possible to determine calibration parameters valid for the whole (global) gravity gradient data set. Nevertheless, regional terrestrial gravity data could be used to validate the measured and calibrated gravity gradients. In addition, a possible use of GOCE high low satellite-to-satellite tracking data to calibrate the common accelerations is explored; it is shown that this approach fails. If more accurate gravity field information becomes available then such a calibration may become feasible.

Bouman, J.; Koop, R.; Tscherning, C. C.; Visser, P.

2004-09-01

18

Assessment of the EGM2008 Gravity Field in Algeria Using Gravity and GPS\\/Levelling Data  

Microsoft Academic Search

\\u000a The present work focuses on the evaluation of the EGM2008 geopotential model that was recently released by the NGA (National Geospatial-Intelligence Agency, US)\\/EGM-development team, in Algeria using the free air gravity anomalies supplied by BGI and GETECH, the precise GPS data collected\\u000a from the international TYRGEONET (TYRhenian GEOdynamical NETwork) and ALGEONET (ALGerian GEOdynamical NETwork) projects and\\u000a the last Algerian local

S. A. Benahmed Daho

19

Algebraic high level nets  

Microsoft Academic Search

Petri nets, well established as a fundamental model of concurrency and as a specification technique for distributed systems, are revisited from an algebraic point of view. In a first step Petri nets can be considered as monoids with well-defined algebraic semantics. Secondly they can be combined with algebraic specifications leading to the concept of algebraic high-level nets with suitable compositionality

Hartmut Ehrig; Julia Padberg; Leila Ribeiro

20

High resolution gravity models combining terrestrial and satellite data  

NASA Technical Reports Server (NTRS)

Spherical harmonic expansions to degree 360 have been developed that combine satellite potential coefficient information, terrestrial gravity data, satellite altimeter information as a direct tracking data type and topographic information. These models define improved representations of the Earth's gravitational potential beyond that available from just satellite or terrestrial data. The development of the degree 360 models, however, does not imply a uniform accuracy in the determination of the gravity field as numerous geographic areas are devoid of terrestrial data or the resolution of such data is limited to, for example, 100 km. This paper will consider theoretical and numerical questions related to the combination of the various data types. Various models of the combination process are discussed with a discussion of various correction terms for the different models. Various sources of gravity data will be described. The new OSU91 360 model will be discussed with comparisons made to previous 360 models and to other potential coefficient models that are complete to degree 50. Future directions in high degree potential coefficient models will be discussed.

Rapp, Richard H.; Pavlis, Nikolaos K.; Wang, Yan M.

1992-01-01

21

Sea-level changes, geoid and gravity anomalies due to Pleistocene deglaciation by means of multilayered, analytical Earth models  

NASA Astrophysics Data System (ADS)

A new class of analytical, multilayered, viscoelastic Earth models based on PREM, with an incompressible, linear, viscoelastic Maxwell rheology, is applied to the modeling of global sea-level changes due to Pleistocene deglaciation. Until now, analytical schemes based on normal mode theory, have dealt with at most five layers, an elastic lithosphere, a three layered mantle including a transition zone, and a core ( Spada et al., 1992. Geophys. J. Int. 109, 683-700). The novelty of our approach, used for the first time in sea-level studies, stands on an analytical scheme that can reproduce continuous elastic and rheological stratification when a sufficient number of layers is taken into account. We specifically assess the importance of our results for the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission. GOCE will resolve the gravity field with a spatial resolution (half-wavelength) of 75 km and amplitude of 1.5 mgal, with a uniform coverage over the Earth, including presently unsurveyed, remote areas. Our models lead to post-glacial rebound induced free air gravity anomalies of a few mgals peak-to-peak in the harmonic degree range l=80-200, which will be discernible by GOCE. This finding demonstrates that post-glacial rebound has a high frequency component in the gravity field that can in principle be resolved by high resolution gravity satellite missions. We show that post-glacial rebound can contribute a substantial fraction to present-day sea-level variations and point out that for the Mediterranean Sea they are of the same order of magnitude as those induced by tectonic processes.

Di Donato, G.; Vermeersen, L. L. A.; Sabadini, R.

2000-05-01

22

Gravity Wave Parameters Derived from High Vertical Resolution U.S. Radiosonde Data  

Microsoft Academic Search

Five years of high vertical resolution U.S. radiosonde data have been analyzed to derive important gravity wave parameters such as intrinsic frequency, vertical wavelength, and vertical and horizontal directions of gravity wave energy propagation. It is found that all these parameters display distinctive latitudinal and seasonal variations. Most dominant gravity wave intrinsic frequencies divided by the Coriolis parameter are around

L. Wang; M. A. Geller; M. J. Alexander; D. Fritts

2003-01-01

23

High-Resolution Infra-Red Imaging Studies of Mesospheric Gravity Waves (Invited)  

NASA Astrophysics Data System (ADS)

This presentation highlights new research capabilities and recent results focusing on polar latitudes using two new infra-red imaging systems operating at the ALOMAR Arctic Observatory, Norway and at the Amundsen-Scott Base, South Pole, Antarctica. The Advanced Mesospheric Temperature Mapper (AMTM) is a novel infrared digital imaging system that measures selected emission lines in the mesospheric OH (3,1) band (at ~1.5?m) to create high-quality intensity and temperature maps of a broad spectrum of mesospheric gravity waves (with periods ranging from several minutes to many hours). The data are obtained with an unprecedented spatial (~0.5 km) and temporal (typically 30 sec) resolution over a large 120° field of view enabling detailed measurements of wave propagation and dissipation at the ~87 km level, even in the presence of strong aurora. Several new results will be presented and discussed, including high-resolution imaging studies of gravity wave breaking, first evidence of gravity wave 'self-acceleration' and new coordinated lidar, radar and AMTM measurements of gravity wave propagation and ducting at mid-latitudes.

Taylor, M. J.; Pautet, P.; Zhao, Y.; Pendleton, W. R.; Yuan, T.; Esplin, R.; McLain, D.; Fritts, D. C.; Stober, G.

2013-12-01

24

Changing Gravity Level and the Development of Animals.  

National Technical Information Service (NTIS)

Space biology has accumulated a great body of information concerning the influence of microgravity upon objects of varying levels of biological organization; from microorganisms to higher animals and humans. However, the choice of biological objects was i...

L. V. Serova

1993-01-01

25

Bed topography of Store Glacier, Greenland from high-resolution airborne gravity data  

NASA Astrophysics Data System (ADS)

Store Glacier is a major west Greenland outlet tidewater glacier draining an area of 30,000 square km into Uummannaq Fjord, flowing at a speed of 4.8 km per year at the terminus. The bed topography of the glacier is poorly known and the fjord bathymetry has only been partially surveyed for the first time in 2012. In this study, we present a new approach on the modeling of glacier thickness and sea floor bathymetry based on high resolution gravity constrained with other observations. In August 2012, we acquired a 250m spacing grid of free-air gravity data at a speed of 50 knots with accuracy at sub-milligal level. We constrain the 3D inversion of these gravity data with ship-borne bathymetry near the glacier front and radar-derived ice thickness on grounded ice to derive a seamless map of bed topography of grounded ice and sea floor. Comparison of the new topography with prior maps reveals vast differences. Prior bathymetry (IBCAO3) has an ice front grounded at sea level whereas observations show a depth of 550m. On grounded ice, the data reveal the subglacial topography at an unprecedented level of spatial details. We discuss the impact of the results on the modeling of the glacier flow and the understanding of its interaction with ocean thermal forcing and surface mass balance.

An, L.; Rignot, E. J.

2013-12-01

26

Very extended E8 and A8 at low levels, gravity and supergravity  

Microsoft Academic Search

We define a level for a large class of Lorentzian Kac-Moody algebras. Using this we find the representation content of very extended AD-3 and E8 (i.e., E11) at low levels in terms of AD-1 and A10 representations, respectively. The results are consistent with the conjectured very extended A8 and E11 symmetries of gravity and maximal supergravity theories given respectively in

Peter West

2003-01-01

27

Testing gravity at the second post-Newtonian level through gravitational deflection of massive particles  

SciTech Connect

Expression for second post-Newtonian level gravitational deflection angle of massive particles is obtained in a model independent framework. Comparison of theoretical values with the observationally constructed values of post-Newtonian parameters for massive particles offers the future possibility of testing at that level competing gravitational theories as well as the equivalence principle. Advantage of studying gravitational deflection of massive particles over that of massless particles in testing gravity is discussed.

Bhadra, A.; Sarkar, K.; Nandi, K. K. [High Energy and Cosmic Ray Research Centre, University of North Bengal, Siliguri, WB 734013 (India); Department of Mathematics, University of North Bengal, Siliguri, WB 734013 (India)

2007-06-15

28

High-accuracy, high-resolution gravity profiles from 2 years of the Geosat Exact Repeat Mission  

NASA Technical Reports Server (NTRS)

Satellite altimeter data from the first 44 repeat cycles (2 years) of the Geosat Exact Repeat Mission (EWRM) were averaged to improve accuracy, resolution and coverage of the marine gravity field. Individual 17-day repeat cycles were first edited and differentiated, resulting in the along-track vertical deflection (i.e., gravity disturbance). To increase the signal-to-noise ratio, 44 of these cycles were then averaged to form a single highly accurate vertical deflection profile. The largest contribution to the vertical deflection error is short-wavelength altimeter noise and longer-wavelength oceanographic variability; the combined noise level is typically 6 microrad. Both types of noise are reduced by averaging many repeat cycles. Over most ocean areas the uncertainty of the average profile is less than 1 microrad which corresponds to 1 mgal of along-track gravity disturbance. However, in areas of seasonal ice coverage, its uncertainty can exceed 5 microrad. To assess the resolution of individual and average Geosat gravity profiles, the cross-spectral analysis technique was applied to repeat profiles. Individual Geosat repeat cycles are coherent (greater than 0.5) for wavelengths greater than about 30 km and become increasingly incoherent at shorter wavelengths.

Sandwell, David T.; Mcadoo, David C.

1990-01-01

29

Microfluidic platform for electrophysiological studies on Xenopus laevis oocytes under varying gravity levels.  

PubMed

Voltage clamp measurements reveal important insights into the activity of membrane ion channels. While conventional voltage clamp systems are available for laboratory studies, these instruments are generally unsuitable for more rugged operating environments. In this study, we present a non-invasive microfluidic voltage clamp system developed for the use under varying gravity levels. The core component is a multilayer microfluidic device that provides an immobilisation site for Xenopus laevis oocytes on an intermediate layer, and fluid and electrical connections from either side of the cell. The configuration that we term the asymmetrical transoocyte voltage clamp (ATOVC) also permits electrical access to the cytosol of the oocyte without physical introduction of electrodes by permeabilisation of a large region of the oocyte membrane so that a defined membrane patch can be voltage clamped. The constant low level air pressure applied to the oocyte ensures stable immobilisation, which is essential for keeping the leak resistance constant even under varying gravitational forces. The ease of oocyte mounting and immobilisation combined with the robustness and complete enclosure of the fluidics system allow the use of the ATOVC under extreme environmental conditions, without the need for intervention by a human operator. Results for oocytes over-expressing the epithelial sodium channel (ENaC) obtained under laboratory conditions as well as under conditions of micro- and hypergravity demonstrate the high reproducibility and stability of the ATOVC system under distinct mechanical scenarios. PMID:21870012

Schaffhauser, Daniel F; Andrini, Olga; Ghezzi, Chiara; Forster, Ian C; Franco-Obregón, Alfredo; Egli, Marcel; Dittrich, Petra S

2011-10-21

30

Fundamentals of gravity level dependent two-phase flow and heat transfer-A tutorial  

NASA Astrophysics Data System (ADS)

Multiphase flow, the simultaneous flow of the different phases (states of matter) gas, liquid and solid, strongly depends on the level and direction of gravitation, since these influence the spatial distribution of the phases, having different densities. Many investigations concern behavior of liquid-solid flows (e.g. in mixing, crystal growing, or materials processing) or gas-solid flows (e.g. in cyclones or combustion equipment). But of major interest for aerospace applications are the more complicated liquid-vapor or liquid-gas flows, being characteristic for aerospace thermal control systems, life sciences systems and propellant systems. Especially for liquid-vapor flow in aerospace two-phase thermal control systems, the phenomena become extremely complicated, because of heat and mass exchange between the phases by evaporation, condensation, and flashing. Though very many publications (textbooks, conference proceedings, journal articles) concern two-phase flow and heat transfer, publications on the impact of reduced gravity are very scarce. This is the main driver for carrying out research in micro-gravity. Various heat and mass transfer issues of two-phase heat transport technology for space applications are discussed, focusing on the most complicated case of liquid-vapor flow with heat and mass exchange. Simpler cases, like adiabatic or isothermal liquid-vapor flow or liquid-gas flow, can be derived from this case, by setting various terms in the constitutive equations equal to zero. The discussions start with the background of the research, followed by a short description of two-phase flow and heat transfer phenomena. The impact of the gravity level will be assessed, including development supporting theoretical work: Thermal/gravitational scaling of two-phase flow and heat transport in two-phase thermal control loops, including gravity level dependent two-phase flow pattern mapping and condensation issues. Outcomes of theoretical work are compared with results of experiments, done on earth and in micro-gravity. .

Delil, A. A. M.

2001-02-01

31

High resolution IR spectrometry and detection of atmospheric gravity waves in the upper atmosphere of Jupiter  

NASA Astrophysics Data System (ADS)

The Galileo and the Cassini observations at Jupiter returned a large volume of information about the planet's atmosphere. Some of the results posed new questions that need to be addressed. The energy balance of the jovian thermosphere still presents a problem in our understanding of the nature of the energy source that provides for the observed high thermospheric temperatures. The Galileo probe temperature profile showed an imbedded wavelike structure in the thermosphere. The same pressure region has been also sampled through radio occultations. The derived electron density profiles show a system of several narrow peaks in the lower ionosphere. They too have been successfully modeled as signatures of high altitude atmospheric gravity waves. Atmospheric gravity waves are potentially an important mechanism of energy and momentum transport in Jupiter's upper atmosphere. At the moment we have no direct information about the level of wave activity (rate of wave occurrence , amplitudes, horizontal wavelengths, wave periods, global distribution on the planet, direction of propagation, possible sources of waves) in order to be able to assess the role of atmospheric waves in the dynamics of Jupiter's upper atmosphere. We present a study of the effects of atmospheric gravity waves on the H3+ emission of Jupiter and assess the fisability of wave detection through high resolution infrared spectrometry. This study is in support of the science definition of the planed joint NASA/ESA Europa Jupiter System Mission (EJSM). We have developed a 2-D, time dependent fully nonlinear model of the chemical and the dynamic response of the ionospheric plasma to the propagation of atmospheric gravity waves. The model is coupled with a H3+ radiative transfer model to estimate the magnitude of the expected observable signature in the H3+ IR emission. The detection and the characterization of the gravity wave modes present in the Jovian atmosphere will allow us to estimate the amount of energy and momentum directly deposited in the thermosphere and their role in the meridional circulation and secondary pole-to-equator energy transport. From the model, a list of scientific specifications for a dedicated instrument for EJSM/Ganymede orbiter will be derived, in order to fill technical specifications. An infrared high resolution spectro-imager working in the H3+ emission range (3.5-4 micron) would give access to fine tuned atmospheric sounding. A dedicated observation strategy will allow characterization of atmospheric gravity waves in Jupiter’s thermosphere on a global scale and will answer the questions about the energy transport in the jovian upper atmosphere. This work is supported by CNES and NASA under grant NNX07AF29G issued through the Planetary Atmospheres program.

Matcheva, K. I.; Barrow, D. J.; Drossart, P.

2009-12-01

32

Tethered gravity laboratories study  

NASA Technical Reports Server (NTRS)

The use is studied of tether systems to improve the lowest possible steady gravity level on the Space Station. Particular emphasis is placed by the microgravity community on the achievement of high quality microgravity conditions. The tether capability is explored for active control of the center of gravity and the analysis of possible tethered configurations.

Lucchetti, F.

1989-01-01

33

High precision absolute gravity gradiometry with atom interferometry  

Microsoft Academic Search

An absolute gravity gradiometer was demonstrated using atom interference techniques. This is the first realization of an gradiometer which uses an absolute standard for its calibration. A gravity gradiometer measures spatial changes in the gravitational field over a fixed baseline by making simultaneous acceleration measurements with two spatially separate accelerometers. The gradiometer has a differential sensitivity of 4 x 10-9

Jeffrey Michael McGuirk

2002-01-01

34

Cross-Coupling and Off-Leveling Errors in Gravity Measurements at Sea  

Microsoft Academic Search

By digitally cross-multiplying 5- to 15.min traces representing the surge accelera- tion of the ship and the position of the gravity meter beam, 35 separate cross-coupling calcula- tions were made under varying sea conditions. Similarly, 13 pitch and roll off-leveling errors were calculated. The cross-coupling errors ranged from about --27 regal for a heavy bow sea (rms surge -- 23.9

Robert E. Wall; Manik Talwani; J. Lamar Worzel

1966-01-01

35

Investigation of Different Methods for the Combination of Gravity and GPS\\/Levelling Data  

Microsoft Academic Search

Two different methods for the combined computation of the quasigeoid are compared in a test area in Germany. Both methods are based on the re- move-restore technique and use the global geopotential model EGM96, point gravity data with a spacing of a few km, a digital terrain model and GPS\\/levelling control points (with a spacing of about 25 km). In

H. Denker; W. Torge; G. Wenzel; J. Ihde; U. Schirmer

2000-01-01

36

Transformation between gravimetric and GPS\\/levelling-derived geoids using additional gravity information  

Microsoft Academic Search

The transformation from the gravimetric to the GPS\\/levelling-derived geoid using additional gravity information for the covariance function of geoid height differences has been investigated in a test area in south-western Canada. A “corrector surface” model, which accounts for datum inconsistencies, long-wavelength geoid errors, vertical network distortions and GPS errors, has been constructed using least-squares collocation. The local covariance function of

R. S. Grebenitcharsky; E. V. Rangelova; M. G. Sideris

2005-01-01

37

Transformation between gravimetric and GPS\\/levelling-derived geoids using additional gravity information  

Microsoft Academic Search

The transformation from the gravimetric to the GPS\\/levelling-derived geoid using additional gravity information for the covariance function of geoid height differences has been investigated in a test area in south-western Canada. A ``corrector surface'' model, which accounts for datum inconsistencies, long-wavelength geoid errors, vertical network distortions and GPS errors, has been constructed using least-squares collocation. The local covariance function of

R. S. Grebenitcharsky; E. V. Rangelova; M. G. Sideris

2005-01-01

38

Generating high freestream turbulence levels  

Microsoft Academic Search

This paper presents a method of generating a highly turbulent freestream flow, up to levels of 20% with a relatively uniform mean velocity field. This method was developed as a result of a combined water channel and wind tunnel study. The method for generating these high turbulence levels includes using high-velocity jets issuing into a mainstream cross-flow. A range of

K. A. Thole; D. G. Bogard; J. L. Whan-Tong

1994-01-01

39

Probing Gravity in the High-Redshift Universe with HETDEX  

NASA Astrophysics Data System (ADS)

The addition of dark matter and dark energy to general relativity is degenerate with a modification of the dependence of curvature on the stress-energy tensor in the absence of exotic sources of matter and energy; it is thus valuable to explore the latter as a potential improvement over the former. Though it is inherently difficult to distinguish existing evidence for the general relativity paradigm from that of its more promising alternatives, such theories are associated with different histories for the largely unexplored growth of structure. Zhang, et al. (2007) have enabled discrimination of these possibilities via a new observable parameter EG and have predicted the efficacy of several future astronomical surveys to determine its value. In this work, we examine the ability of the Hobby Eberly Telescope Dark Energy Experiment (HETDEX) to contribute to calculations of this indicator of gravity at the highest redshifts (1.9 < z < 3.5). We show that a prerequisite of such a measurement is a deeper understanding of the nature of Lyman-? emitting galaxies (LAEs). If HETDEX can constrain the statistical properties of the typical LAE velocity dispersion, then it will not be necessary to wait for the (as yet unplanned) next generation of high-resolution spectrographs to obtain a test of general relativity in the high-redshift universe.

Malz, A. I.; Shandera, S.

2014-01-01

40

Effects of varying gravity levels in parabolic flight on the size-mass illusion.  

PubMed

When an observer lifts two objects with the same weight but different sizes, the smaller object is consistently reported to feel heavier than the larger object even after repeated trials. Here we explored the effect of reduced and increased gravity on this perceptual size-mass illusion. Experiments were performed on board the CNES Airbus A300 Zero-G during parabolic flights eliciting repeated exposures to short periods of zero g, 0.16 g, 0.38 g, one g, and 1.8 g. Subjects were asked to assess perceived heaviness by actively oscillating objects with various sizes and masses. The results showed that a perceptual size-mass illusion was clearly present at all gravity levels. During the oscillations, the peak arm acceleration varied as a function of the gravity level, irrespective of the mass and size of the objects. In other words we did not observe a sensorimotor size-mass illusion. These findings confirm dissociation between the sensorimotor and perceptual systems for determining object mass. In addition, they suggest that astronauts on the Moon or Mars with the eyes closed will be able to accurately determine the relative difference in mass between objects. PMID:24901519

Clément, Gilles

2014-01-01

41

Effects of Varying Gravity Levels in Parabolic Flight on the Size-Mass Illusion  

PubMed Central

When an observer lifts two objects with the same weight but different sizes, the smaller object is consistently reported to feel heavier than the larger object even after repeated trials. Here we explored the effect of reduced and increased gravity on this perceptual size-mass illusion. Experiments were performed on board the CNES Airbus A300 Zero-G during parabolic flights eliciting repeated exposures to short periods of zero g, 0.16 g, 0.38 g, one g, and 1.8 g. Subjects were asked to assess perceived heaviness by actively oscillating objects with various sizes and masses. The results showed that a perceptual size-mass illusion was clearly present at all gravity levels. During the oscillations, the peak arm acceleration varied as a function of the gravity level, irrespective of the mass and size of the objects. In other words we did not observe a sensorimotor size-mass illusion. These findings confirm dissociation between the sensorimotor and perceptual systems for determining object mass. In addition, they suggest that astronauts on the Moon or Mars with the eyes closed will be able to accurately determine the relative difference in mass between objects.

Clement, Gilles

2014-01-01

42

Degraded EEG response of the human brain in function of gravity levels by the method of chaotic attractor  

NASA Astrophysics Data System (ADS)

The measurement of the influence of different gravity levels on the brain allows to explain how humans react to microgravity in space and to predict the adaptation capability of astronauts. Human electroencephalographic (EEG) signals were recorded during low and high gravity phases of three consecutive days of parabolic flights on the Caravelle aircraft in 1991. EEG signals were processed, using the method of correlation dimensions d of chaotic strange attractors. Results show clear differences between the three flights, with a general decrease over time in the attractor dimensions, a measure of the brain response to changing g levels. However, the dimension is not a one-to-one relation with g levels, as additional variations are observed. Two hypotheses are introduced, the "fatigue/stress" and the " g stress" hypotheses corresponding, respectively, to long-term fatigue accumulated over the three flights, and to short-term fatigue in response to change in g levels. The former explains the overall decrease of dimensions, the latter yields additional variations on shorter time scales. As the brain response degrades with time, at least six degraded modes were observed, explained by both short- and long-term fatigue.

Pletser, Vladimir; Quadens, Olga

43

Convective Sources of Gravity Waves from US High Resolution Radiosonde Data  

Microsoft Academic Search

Expressions derived from gravity wave polarization relations indicate the energy of vertical velocity fluctuations, VE, should be more sensitive to higher frequency waves than the kinetic energy of the horizontal velocities, KE, or the potential energy of the temperature fluctuations, PE. It is demonstrated that these different gravity wave energies derived from high vertical-resolution radiosonde soundings have different annual variations,

J. Gong; M. A. Geller

2009-01-01

44

Very extended E8 and A8 at low levels, gravity and supergravity  

NASA Astrophysics Data System (ADS)

We define a level for a large class of Lorentzian Kac-Moody algebras. Using this we find the representation content of very extended AD-3 and E8 (i.e., E11) at low levels in terms of AD-1 and A10 representations, respectively. The results are consistent with the conjectured very extended A8 and E11 symmetries of gravity and maximal supergravity theories given respectively in preprints hep-th/0104081 and hep-th/0107209. We explain how these results provided further evidence for these conjectures.

West, Peter

2003-06-01

45

High-precision Gravity Measurements of the Superconducting Gravimeter 057 at Lhasa Station  

NASA Astrophysics Data System (ADS)

Among more than thirty superconducting gravimeters (SGs) all over the world, the superconducting gravimeter 057 (SG057) at Lhasa station is the unique one installed at the Tibetan Plateau, the highest plateau in the world. In the study, the new calibration factor of the SG057 is computed for the first time using gravity data recorded by LCR-ET20 gravimeter at the same station. The determined scale value of SG057 is -77.5585±0.0136 microgals / Volt, and the relative accuracy is about 5‰ . Because there are almost 1 year recordings of the LCR-ET20 gravimeter at Wuhan superconducting gravimeter station before it is installed at Lhasa station, the scale value of the LCR-ET20 gravimeter is recalibrated with the Wuhan international gravitational tidal benchmark values before it is used at Lhasa station. In this way, the gravity tidal observations recorded at Lhasa station can be unified to the Wuhan international gravitational tidal benchmark values. With the determined new scale value, the gravity tidal recordings of SG057 are calibrated and harmonic analysis is carried out with the calibrated data. Then, high-precision tidal parameters are obtained. Accurate tidal gravity correction is achieved in the Tibet area. After the gravity influence of the station air pressure is corrected, the gravity residual of SG057 is calculated. Further considering the absolute gravity measurements, the gravity residual of SG057 is expected to show the detailed behavior of the gravity variation caused by the uplift of the Tibetan plateau.

Chen, X. D.; Sun, H. P.; Xu, H. Z.; Xu, J. Q.; Hao, X. H.

2012-04-01

46

Validation of ERS-1 and High-Resolution Satellite Gravity with in-situ Shipborne Gravity over the Indian Offshore Regions: Accuracies and Implications to Subsurface Modeling  

Microsoft Academic Search

Geoid and gravity anomalies derived from satellite altimetry are gradually gaining importance in marine geoscientific investigations. Keeping this in mind, we have validated ERS-1 (168 day repeat) altimeter data and very high-resolution free-air gravity data sets generated from Seasat, Geosat GM, ERS-1 and TOPEX\\/POSEIDON altimeters data with in-situ shipborne gravity data of both the Bay of Bengal and the Arabian

Sirsendu Chatterjee; Rudradeb Bhattacharyya; Laju Michael; Kolluru Sree Krishna; Tapan Jyoti Majumdar

2007-01-01

47

Covariant loop quantum gravity, low-energy perturbation theory, and Einstein gravity with high-curvature UV corrections  

NASA Astrophysics Data System (ADS)

A low-energy perturbation theory is developed from the nonperturbative framework of covariant loop quantum gravity (LQG) by employing the background-field method. The resulting perturbation theory is a two-parameter expansion in the semiclassical and low-energy regime. The two expansion parameters are the large spin and small curvature. The leading-order effective action coincides with the Regge action, which well approximates the Einstein-Hilbert action in the regime. The subleading corrections organized by the two expansion parameters give the modifications of the Regge action in the quantum and high-energy regime from LQG. The perturbation theory developed here shows for the first time that covariant LQG produces the high-curvature corrections to Einstein-Regge gravity. This result means that LQG is not a naive quantization of Einstein gravity; rather, it provides the UV modification. The result of the paper may be viewed as the first step toward understanding the UV completeness of LQG.

Han, Muxin

2014-06-01

48

Cognitive high level information fusion  

Microsoft Academic Search

Fusion of sensor and communication data currently can only be performed at a late processing stage after sensor and textual information are formulated as logical statements at appropriately high level of abstraction. Contrary to this it seems, the human mind integrates sensor and language signals seamlessly, before signals are understood, at pre-conceptual level. Learning of conceptual contents of the surrounding

Leonid I. Perlovsky

2007-01-01

49

Silicone oil with high specific gravity for intraocular use  

Microsoft Academic Search

Silicone oil with a higher specific gravity than that of intraocular fluid or polydimethylsiloxane may have special indications in vitreoretinal surgery. Trifluorsiloxane is such a substance, and therefore its biological compatibility was investigated in rabbit eyes. It was found that this substance was clinically well tolerated within the observation time of up to 6 months, even if there was some

V P Gabel; A Kampik; C Gabel; D Spiegel

1987-01-01

50

High-Precision Simulation of the Gravity Field of Rapidly-Rotating Barotropes in Hydrostatic Equilibrium  

NASA Astrophysics Data System (ADS)

The so-called theory of figures (TOF) uses potential theory to solve for the structure of highly distorted rotating liquid planets in hydrostatic equilibrium. TOF is noteworthy both for its antiquity (Maclaurin 1742) and its mathematical complexity. Planned high-precision gravity measurements near the surfaces of Jupiter and Saturn (possibly detecting signals ~ microgal) will place unprecedented requirements on TOF, not because one expects hydrostatic equilibrium to that level, but because nonhydrostatic components in the surface gravity, at expected levels ~ 1 milligal, must be referenced to precise hydrostatic-equilibrium models. The Maclaurin spheroid is both a useful test of numerical TOF codes (Hubbard 2012, ApJ Lett 756:L15), and an approach to an efficient TOF code for arbitrary barotropes of variable density (Hubbard 2013, ApJ 768:43). For the latter, one trades off vertical resolution by replacing a continuous barotropic pressure-density relation with a stairstep relation, corresponding to N concentric Maclaurin spheroids (CMS), each of constant density. The benefit of this trade-off is that two-dimensional integrals over the mass distributions at each interface are reduced to one-dimensional integrals, quickly and accurately evaluated by Gaussian quadrature. The shapes of the spheroids comprise N level surfaces within the planet and at its surface, are gravitationally coupled to each other, and are found by self-consistent iteration, relaxing to a final configuration to within the computer's precision limits. The angular and radial variation of external gravity (using the usual geophysical expansion in multipole moments) can be found to the limit of typical floating point precision (~ 1.e-14), much better than the expected noise/signal for either the Juno or Cassini gravity experiments. The stairstep barotrope can be adjusted to fit a prescribed continuous or discontinuous interior barotrope, and can be made to approximate it to any required precision by increasing N. One can insert a higher density of CMSs toward the surface of an interior model in order to more accurately model high-order gravitational moments. The magnitude of high-order moments predicted by TOF declines geometrically with order number, and falls below the magnitude of expected non-hydrostatic terms produced by interior dynamics at ~ order 10 and above. Juno's sensitivity is enough to detect tidal gravity signals from Galilean satellites. The CMS method can be generalized to predict tidal zonal and tesseral terms consistent with an interior model fitted to measured zonal harmonics. For this purpose, two-dimensional Gaussian quadrature is necessary at each CMS interface. However, once the model is relaxed to equilibrium, one need not refit the model to the average zonal harmonics because of the smallness of the tidal terms. I will describe how the CMS method has been validated through comparisons with standard TOF models for which fully or partially analytic solutions exist, as well as through consistency checks. At this stage in software development in preparation for Jupiter orbit, we are focused on increasing the speed of the code in order to more efficiently search the parameter space of acceptable Jupiter interior models, as well as to interface it with advanced hydrogen-helium equations of state.

Hubbard, W. B.

2013-12-01

51

High-precision gravity measurements using atom interferometry  

Microsoft Academic Search

We have built an atom interferometer that can measure g, the local acceleration due to gravity, with a resolution of ?g\\/g = 2 × 10?8 after a single 1.3 s measurement cycle, 3 × 10?9 after 1 min and 1 × 10?10 after two days of integration time. The difference between our value for g and one obtained by a

A. Peters; K. Y. Chung; S. Chu

2001-01-01

52

Silicone oil with high specific gravity for intraocular use.  

PubMed Central

Silicone oil with a higher specific gravity than that of intraocular fluid or polydimethylsiloxane may have special indications in vitreoretinal surgery. Trifluorsiloxane is such a substance, and therefore its biological compatibility was investigated in rabbit eyes. It was found that this substance was clinically well tolerated within the observation time of up to 6 months, even if there was some neovascularisation from the inferior limbus. Histologically both an inflammatory response and tissue impregnation were more pronounced than with normal polydimethylsiloxane. Images

Gabel, V P; Kampik, A; Gabel, C; Spiegel, D

1987-01-01

53

High Resolution Measurement of Gravity Deflections from the Vertical over Long Baselines  

NASA Astrophysics Data System (ADS)

Sander Geophysics has operated its AIRGrav system for over ten years and has worked to continually improve the accuracy and resolution of the entire system. New data processing techniques have allowed the extraction of the gravity deflections from the vertical (horizontal components of the airborne gravity data) in addition to the traditionally used scalar gravity measurement, and operations have expanded to acquisition speeds ranging from 15 km/hr to over 1000 km/hr. The gravimeter is based on an assembly of gyroscopes and accelerometers held in a stable spatial orientation, and has horizontal accelerometers of sufficient accuracy that it is possible to estimate the horizontal components of the gravity vector. "Geodetic quality" GPS receivers are used to collect data at a high rate, and these data are post-processed with the recorded gravimeter data to produce estimates of the three gravity vector components. The estimates of the gravity deflections from the vertical are very sensitive to initial settings of sensor parameters, unmodelled gyro and other sensor errors, as well as unpredictable changes in the sensor errors. As a consequence, it is necessary to constrain the long-wavelength errors using some external source of data. All three components of gravity can be measured to sub-mGal resolution, providing the horizontal components can be constrained in a long-wavelength sense. Data recorded during several flights each consisting of a single long line will be presented, showing the estimates of the gravity deflections from the vertical and comparing them with the best available reference data. Figure 1 illustrates the extent of the long lines. The examples will demonstrate that the horizontal gravity components can be measured with high repeatability, and agree with geoid models of the highest order available. Results from airborne and marine surveys acquired at a wide range of speeds will also be presented to illustrate the resolution attained using these varied platforms.

Sander, S.; Ferguson, S.; Sander, L.; Elieff, S. H.

2011-12-01

54

High pressure liquid level monitor  

DOEpatents

A liquid level monitor for tracking the level of a coal slurry in a high-pressure vessel including a toroidal-shaped float with magnetically permeable bands thereon disposed within the vessel, two pairs of magnetic field generators and detectors disposed outside the vessel adjacent the top and bottom thereof and magnetically coupled to the magnetically permeable bands on the float, and signal processing circuitry for combining signals from the top and bottom detectors for generating a monotonically increasing analog control signal which is a function of liquid level. The control signal may be utilized to operate high-pressure control valves associated with processes in which the high-pressure vessel is used.

Bean, Vern E. (Frederick, MD); Long, Frederick G. (Ijamsville, MD)

1984-01-01

55

Verification of heights above global mean sea level from high-degree global geopotential models by using leveling data  

NASA Astrophysics Data System (ADS)

The dedicated satellite gravity missions CHAllenging Minisatellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity field and steady-state Ocean Circulation Explorer (GOCE) and their recent and expected Global Geopotential Models (GGMs) present new opportunities for the determination of gravity-related heights. Global Positioning System (GPS), the recent GGMs, and reference value W0 are used to study the construction of different height systems and verify high-degree global geopotential models. This approach matches well with all theoretical basics of height systems. The presented numerical strategy is independent of height anomaly and geoid undulation computation. Using the International Terrestrial Reference Frame (ITRF) coordinates at 47 GPS stations of the Turkish National Vertical Control Network (TNVCN), the gravity potential values are computed based on new-generation GGMs. The computed gravity potentials are converted into different height systems. A global mean sea level represented by a geoid potential has been taken as reference for the heights. The GGM-derived geopotential numbers, Helmert orthometric, and Molodensky normal heights at the GPS stations are compared against the results from precise leveling. The numerical application demonstrates that three types of gravity-related heights can be determined with a similar accuracy level (12 cm). When long-term deformations such as tectonic activity and possible land subsidence/uplift effects on the heights of benchmarks of the TNVCN are taken into account, the obtained results are significant, and also, under the light of the dedicated satellite gravity missions, high-resolution GGMs such as EGM2008 have an important potential for the realization of a unified height system. The experimental study shows a datum bias of 38 2 cm between the TNVCN datum and the global datum.

Ustun, Aydin

2011-12-01

56

Centrifugal Sieve for Gravity-Level-Independent Size Segregation of Granular Materials  

NASA Technical Reports Server (NTRS)

Conventional size segregation or screening in batch mode, using stacked vibrated screens, is often a time-consuming process. Utilization of centrifugal force instead of gravity as the primary body force can significantly shorten the time to segregate feedstock into a set of different-sized fractions. Likewise, under reduced gravity or microgravity, a centrifugal sieve system would function as well as it does terrestrially. When vibratory and mechanical blade sieving screens designed for terrestrial conditions were tested under lunar gravity conditions, they did not function well. The centrifugal sieving design of this technology overcomes the issues that prevented sieves designed for terrestrial conditions from functioning under reduced gravity. These sieves feature a rotating outer (cylindrical or conical) screen wall, rotating fast enough for the centrifugal forces near the wall to hold granular material against the rotating screen. Conventional centrifugal sieves have a stationary screen and rapidly rotating blades that shear the granular solid near the stationary screen, and effect the sieving process assisted by the airflow inside the unit. The centrifugal sieves of this new design may (or may not) have an inner blade or blades, moving relative to the rotating wall screen. Some continuous flow embodiments would have no inner auger or blades, but achieve axial motion through vibration. In all cases, the shearing action is gentler than conventional centrifugal sieves, which have very high velocity differences between the stationary outer screen and the rapidly rotating blades. The new design does not depend on airflow in the sieving unit, so it will function just as well in vacuum as in air. One advantage of the innovation for batch sieving is that a batch-mode centrifugal sieve may accomplish the same sieving operation in much less time than a conventional stacked set of vibrated screens (which utilize gravity as the primary driving force for size separation). In continuous mode, the centrifugal sieves can provide steady streams of fine and coarse material separated from a mixed feedstock flow stream. The centrifugal sieves can be scaled to any desired size and/or mass flow rate. Thus, they could be made in sizes suitable for small robotic exploratory missions, or for semi-permanent processing of regolith for extraction of volatiles of minerals. An advantage of the continuous-mode system is that it can be made with absolutely no gravity flow components for feeding material into, or for extracting the separated size streams from, the centrifugal sieve. Thus, the system is capable of functioning in a true microgravity environment. Another advantage of the continuous-mode system is that some embodiments of the innovation have no internal blades or vanes, and thus, can be designed to handle a very wide range of feedstock sizes, including occasional very large oversized pieces, without jamming or seizing up.

Walton, Otis R.; Dreyer, Christopher; Riedel, Edward

2013-01-01

57

The CMS high level trigger  

NASA Astrophysics Data System (ADS)

The CMS experiment has been designed with a 2-level trigger system: the Level 1 Trigger, implemented on custom-designed electronics, and the High Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm. A software trigger system requires a tradeoff between the complexity of the algorithms running on the available computing power, the sustainable output rate, and the selection efficiency. Here we will present the performance of the main triggers used during the 2012 data taking, ranging from simpler single-object selections to more complex algorithms combining different objects, and applying analysis-level reconstruction and selection. We will discuss the optimisation of the triggers and the specific techniques to cope with the increasing LHC pile-up, reducing its impact on the physics performance.

Gori, Valentina

2014-05-01

58

The CMS High Level Trigger  

NASA Astrophysics Data System (ADS)

The CMS experiment has been designed with a two-level trigger system: the Level-1 Trigger, implemented in custom-designed electronics, and the High-Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm. A software trigger system requires a tradeoff between the complexity of the algorithms running with the available computing power, the sustainable output rate, and the selection efficiency. We present the performance of the main triggers used during the 2012 data taking, ranging from simple single-object selections to more complex algorithms combining different objects, and applying analysis-level reconstruction and selection. We discuss the optimisation of the trigger and the specific techniques to cope with the increasing LHC pile-up, reducing its impact on the physics performance.

Trocino, Daniele

2014-06-01

59

Effect of Gravity Level on the Particle Shape and Size During Zeolite Crystal Growth  

NASA Technical Reports Server (NTRS)

A microscopic diffusion model is developed to represent solute transport in the boundary layer of a growing zeolite crystal. This model is used to describe the effect of gravity on particle shape and solute distribution. Particle dynamics and crystal growth kinetics serve as the boundary conditions of flow and convection-diffusion equations. A statistical rate theory is used to obtain the rate of solute transport across the growing interface, which is expressed in terms of concentration and velocity of solute species. Microgravity can significantly decrease the solute velocity across the growing interface compared to its earth-based counterpart. The extent of this reduction highly depends on solute diffusion constant in solution. Under gravity, the flow towards the crystal enhances solute transport rate across the growing interface while the flow away from crystals reduces this rate, suggesting a non-uniform growth rate and thus an elliptic final shape. However, microgravity can significantly reduce the influence of flow and obtain a final product with perfect spherical shape. The model predictions compare favorably with the data of space experiment of zeolites grown in space.

Song, Hong-Wei; Ilebusi, Olusegun J.; Sacco, Albert, Jr.

2003-01-01

60

High?degree gravity models from GRAIL primary mission data  

NASA Astrophysics Data System (ADS)

have analyzed Ka?band range rate (KBRR) and Deep Space Network (DSN) data from the Gravity Recovery and Interior Laboratory (GRAIL) primary mission (1 March to 29 May 2012) to derive gravity models of the Moon to degree 420, 540, and 660 in spherical harmonics. For these models, GRGM420A, GRGM540A, and GRGM660PRIM, a Kaula constraint was applied only beyond degree 330. Variance?component estimation (VCE) was used to adjust the a priori weights and obtain a calibrated error covariance. The global root?mean?square error in the gravity anomalies computed from the error covariance to 320×320 is 0.77 mGal, compared to 29.0 mGal with the pre?GRAIL model derived with the SELENE mission data, SGM150J, only to 140×140. The global correlations with the Lunar Orbiter Laser Altimeter?derived topography are larger than 0.985 between ?=120 and 330. The free?air gravity anomalies, especially over the lunar farside, display a dramatic increase in detail compared to the pre?GRAIL models (SGM150J and LP150Q) and, through degree 320, are free of the orbit?track?related artifacts present in the earlier models. For GRAIL, we obtain an a posteriori fit to the S?band DSN data of 0.13 mm/s. The a posteriori fits to the KBRR data range from 0.08 to 1.5 ?m/s for GRGM420A and from 0.03 to 0.06 ?m/s for GRGM660PRIM. Using the GRAIL data, we obtain solutions for the degree 2 Love numbers, k20=0.024615±0.0000914, k21=0.023915±0.0000132, and k22=0.024852±0.0000167, and a preliminary solution for the k30 Love number of k30=0.00734±0.0015, where the Love number error sigmas are those obtained with VCE.

Lemoine, Frank G.; Goossens, Sander; Sabaka, Terence J.; Nicholas, Joseph B.; Mazarico, Erwan; Rowlands, David D.; Loomis, Bryant D.; Chinn, Douglas S.; Caprette, Douglas S.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.

2013-08-01

61

Using high-resolution gravity and pumping data to infer aquifer parameters  

NASA Astrophysics Data System (ADS)

Drawdown measurements during a pumping test are often of limited spatial extent but typically provide the only available head observations for developing and evaluating a groundwater model. Previous field and modeling studies have shown gravity data to be complementary to head observations for aquifer-storage-change monitoring and estimating aquifer properties. Although spatially distributed gravity measurements have proven useful for monitoring aquifer storage change and oil and gas extraction, to date, no direct superconducting gravimeter measurements of aquifer response to high-volume pumping have been reported. Data collected from March 2010 to March 2011 with a superconducting gravimeter located 200 m from a public supply well in Tucson, AZ, show a decrease in gravity-up to 10 microgals- primarily correlated with withdrawal of water-mass from pumping, and to a lesser degree, with pumping-induced land surface elevation changes that indicate elastic aquifer compressibility. This small gravity change was scarcely detected with a co-located A10 absolute gravimeter. These gravity data provide an additional tool to evaluate and calibrate a groundwater flow model, and suggest more interesting aquifer-storage dynamics than a simple correlation between drawdown and gravity change. The superconducting gravimeter, together with the desert environment and urban setting where direct recharge is not present and non-pumping hydrologic effects are minimal, provides a high signal-to-noise ratio not possible with other instruments.

Kennedy, J.; Pool, D.; Ferre, P. A.; Wilson, C. R.

2011-12-01

62

High Degree and Order Gravity Fields of the Moon Derived from GRAIL Data  

NASA Technical Reports Server (NTRS)

The Gravity Recovery and Interior Laboratory (GRAIL) spacecraft conducted the mapping of the gravity field of the Moon from March 1, 2012 to May 29, 2012. The twin spacecraft acquired highly precise K Band range-rate (KBRR) intersatellite ranging data and Deep Space Network (DSN) data during this prime mission phase from altitudes of 15 to 75 km above the lunar surface over three lunar months. We have processed these data using the NASA GSFC GEODYN orbit determination and geodetic parameter estimation program, and we have determined gravity fields up to degree and order 420 in spherical harmonics. The new gravity solutions show improved correlations with LOLA-derived topography to high degree and order and resolve many lunar features in the geopotential with a resolution of less than 30 km, including for example the central peak of the crater Tycho. We discuss the methodology used for the processing of the GRAIL data, the quality of the orbit determination on the GRAIL satellites and the derivation of the solutions, and their evaluation with independent data, including Lunar Prospector. We show that with these new GRAIL gravity solutions, we can now fit the low altitude, extended mission Lunar Prospector tracking data better than with any previous gravity model that included the LP data.

Lemoine, F. G.; Goossens, S. J.; Sabaka, T. J.; Nicholas, J. B.; Mazarico, E.; Rowlands, D. D.; Loomis, B. D.; Chinn, D. S.; Caprette, D. S.; McCarthy, J. J.; Neumann, G. A.; Zuber, M. T.; Smith, D. E.

2012-01-01

63

High Degree and Order Gravity Fields of the Moon Derived from GRAIL Data  

NASA Astrophysics Data System (ADS)

The Gravity Recovery and Interior Laboratory (GRAIL) spacecraft conducted the mapping of the gravity field of the Moon from March 1, 2012 to May 29, 2012. The twin spacecraft acquired highly precise K Band range-rate (KBRR) intersatellite ranging data and Deep Space Network (DSN) data during this prime mission phase from altitudes of 15 to 75 km above the lunar surface over three lunar months. We have processed these data using the NASA GSFC GEODYN orbit determination and geodetic parameter estimation program, and we have determined gravity fields up to degree and order 420 in spherical harmonics. The new gravity solutions show improved correlations with LOLA-derived topography to high degree and order and resolve many lunar features in the geopotential with a resolution of less than 30 km, including for example the central peak of the crater Tycho. We discuss the methodology used for the processing of the GRAIL data, the quality of the orbit determination on the GRAIL satellites and the derivation of the solutions, and their evaluation with independent data, including Lunar Prospector. We show that with these new GRAIL gravity solutions, we can now fit the low altitude, extended mission Lunar Prospector tracking data better than with any previous gravity model that included the LP data.

Lemoine, F. G.; Goossens, S. J.; Sabaka, T. J.; Nicholas, J. B.; Mazarico, E.; Loomis, B. D.; Chinn, D. S.; Caprette, D.; McCarthy, J. J.; Neumann, G. A.; Zuber, M. T.; Smith, D. E.

2012-12-01

64

Gravity Fountains  

NSDL National Science Digital Library

This activity (located on page 3 of the PDF) is a full inquiry investigation into the forces of gravity and air pressure. Groups of learners will construct a simple gravity fountain by making a hole near the bottom of a 2-liter bottle, filling it with water, then as the bottle empties, collecting measurements of the water levels and length of the stream, to make a graph for analysis. Relates to linked video, DragonflyTV GPS: Gravity Fountain.

Twin Cities Public Television, Inc.

2007-01-01

65

Monitoring Earthquake Fault Slip from Space: Model Implications for a High Precision, High Resolution Dedicated Gravity Mission (Invited)  

NASA Astrophysics Data System (ADS)

Monitoring deformation produced by slip on earthquake faults can be carried out via GPS or InSAR measurements. Both of these types of observations have their advantages and disadvantages, in terms of cost, availability, and technical difficulty. It has been suggested that another method to accomplish many of the same objectives would be via a dedicated gravity mission. The GRACE mission has shown that it is possible to make detailed gravity measurements from space for climate dynamics and other purposes. An important question is what level of accuracy will be needed for precise estimation of fault slip in earthquakes of interest to researchers. To answer this question, we turn to numerical simulations of earthquake fault systems and use these to estimate gravity changes. Rundle (1978) considered the question of gravity changes from dilation sources and thrust faults, and found that gravity changes in these cases were free air anomaly (dilation) and Bouguer anomaly (thrust fault). Walsh and Rice (1978) computed these by a different method and found the same result. Okada (1991) listed gravity and potential Green functions for all possible sources for the general case. Hayes et al (2006) then took the Okada Greens functions and applied them computed from an earlier version of Virtual California earthquake fault system simulations. Those simulations only involved vertical strike slip faults. The current far more advanced generation of Virtual California simulations involves faults of any orientation, dip, and rake. In this talk, we discuss these computations and the implications they have for accuracies needed for a dedicated gravity monitoring mission. Preliminary results are in agreement with previous results from Hayes et al (2006). Computed gravity changes are in the range of tens to hundreds of microgals over distances of few to many tens of kilometers. These values are presumably well within the range of measurement for a modern gravity mission flown either at low altitudes, or via UAVs.

Rundle, J. B.; Sachs, M. K.; Tiampo, K. F.; Fernandez, J.; Turcotte, D. L.; Donnellan, A.; Heien, E. M.; Kellogg, L. H.

2013-12-01

66

On the concentration structure of high-concentration constant-volume fluid mud gravity currents  

NASA Astrophysics Data System (ADS)

An exhaustive laboratory experimental campaign was undertaken in order to elucidate the concentration structure of two-dimensional constant-volume non-Newtonian fluid mud gravity currents. Two sets of experiments were conducted in a lock-exchange tank. The first set of experiments involved measuring the vertical concentration profiles using a siphoning technique; the second set involved auxiliary visual observations. The first set of experiments consisted of 32 experimental runs for four different experimental conditions, with an array of siphoned samples being withdrawn throughout the head and body of the gravity current. From these samples, vertical concentration profiles occurring in constant-volume fluid mud gravity currents were classified and the underlying physical processes that led to the occurrence of observed profiles were discussed. Furthermore, the functional form of the vertical concentration profiles within the head of relatively low-initial-concentration gravity currents was proposed. The relatively high-initial-concentration gravity currents revealed the presence of a lutocline in the current head and body, the presence of which was observed for constant-flux release gravity currents. To our knowledge, this is the first measurement of a lutocline in constant-volume gravity currents. Abrupt transitions, a phenomenon in which the bulk of the suspended sediment in the propagating gravity current drops out, were observed through the concentration profiles and through 15 auxiliary visual experimental runs. It was found that abrupt transitions were caused by the presence of a lutocline. The entrainment of ambient water resulting in the dilution of the gravity current at different concentration contours has been quantified. In a previous work by the authors of this study, it was shown that the initial reduced gravity is directly proportional to the growth rate of the visual area of the two-dimensional current. The analysis of our experimental observations presented in this study, however, showed the initial reduced gravity to be inversely proportional to the growth rate of the area enclosed by concentration contours with higher values than that of the visual area. These seemingly opposing conclusions are rationalized and the considerable practical impacts are discussed.

Jacobson, M. R.; Testik, F. Y.

2013-01-01

67

Testing Plate Reconstructions For The High Arctic Using Crustal Thickness Mapping From Gravity Inversion  

NASA Astrophysics Data System (ADS)

The plate tectonic history of the Amerasia Basin (High Arctic) and its distribution of oceanic and continental lithosphere is poorly known. A new method of gravity inversion with an embedded lithosphere thermal gravity anomaly correction has been applied to the NGA (U) Arctic Gravity Project data to predict crustal thickness and to test different plate reconstructions within the Arctic region. Two end member plate reconstruction models have been tested: in one model the Mendeleev Ridge is rifted from the Canadian margin while in the other it is rifted from the Lomonosov Ridge. The inversion of gravity data to map crustal thickness variation within oceanic and rifted continental margin lithosphere requires the incorporation of a lithosphere thermal gravity anomaly correction for both oceanic and continental lithosphere. Oceanic lithosphere and stretched continental margin lithosphere produce a large negative residual thermal gravity anomaly (up to -380 mGal), for which a correction must be made in order to determine realistic Moho depth by gravity anomaly inversion. The lithosphere thermal model used to predict the lithosphere thermal gravity anomaly correction may be conditioned using plate reconstruction models to provide the age and location of oceanic lithosphere. Two end- member plate reconstruction models have been constructed for the opening of the Amerasia Basin and used to determine lithosphere thermal gravity anomaly corrections: in one model the (presumably) continental Mendeleev Ridge is rifted from the Canadian margin in the Jurassic while in the other it is rifted off the Lomonosov Ridge (Eurasia Basin) in the Late-Cretaceous. Crustal thickness predicted by gravity anomaly inversion for the two plate reconstructions is significantly different in the Makarov Basin because of their different lithosphere thermal gravity corrections. The plate reconstruction with younger Makarov Basin ages gives a crustal thickness of the order 6-8 km thinner than the older Makarov Basin model. A crustal thickness of approximately 20 km has been obtained from seismic refraction data (Lebedeva-Ivanova et al., 2006) which would imply a Late Mid-Cretaceous age for the Makarov Basin. In this case plume-related forces may have contributed to the opening of this basin, as regional plate tectonics predict compression and not extension in the Makarov Basin area at this time.

Alvey, A. D.; Gaina, C.; Kusznir, N. J.; Torsvik, T. H.

2006-12-01

68

Application of Fiber Bragg Grating Level Sensor and Fabry-Pérot Pressure Sensor to Simultaneous Measurement of Liquid Level and Specific Gravity  

Microsoft Academic Search

This study is proposed for obtaining simultaneous measurements of the level and specific gravity of a liquid using a dual-optical-fiber-sensor system comprising a fiber Bragg grating (FBG) level sensor and a Fabry-Pérot (FP) pressure sensor. In the FBG level sensor, the liquid level is derived from the FBG wavelength shift induced when the buoyancy is applied on a cantilever beam.

Chih-Wei Lai; Yu-Lung Lo; Jiahn-Piring Yur; Chin-Ho Chuang

2012-01-01

69

Gain of balance and critical level absorption for inertio gravity waves  

NASA Astrophysics Data System (ADS)

The absorption of an inertio gravity wave (IGW) at critical levels is analyzed in the rotating linear case, and for a constant vertically sheared flow. We give for the first time an exact solution valid over the entire domain, and check its validity by deriving from it the classical values of the transmission and reflection coefficients of the wave |T| = exp( ) - ?°J-(1+-?2)-0.25- and |R| = 0, respectively. Here J is the Richardson number and ? the ratio between the horizontal transverse and along shear wavenumbers. For large J, a WKB analysis permits to interpret this classical result in term of tunneling. In this interpretation, the wave as it arrives to the lowest inertial critical level becomes evanescent (there is a turning point very near the critical level), and the transmitted signal is just the amplitude of this evanescent disturbance at the upper inertial level where it becomes an IGW again. As this evanescent solution is near a quasi-geostrophic solution between the inertial levels we see that it is a gain of balance there that explain the exponential smallness of the transmitted wave. The exact and approximate solutions also permit to describe how the "valve" effect, which amplify the disturbances with phase line tilted in the direction of the isentropes, is only significant when the flow is inertially unstable (when J < 1). In this case, a small incident asymmetric transverse wave can result in a very large disturbance between the inertial levels, a result that establish a correspondence between the absoptive properties of the shear layer and the criteria for flow stability.

Lott, Francois; Millet, Christophe; Vanneste, Jacques

2014-05-01

70

Evaluation of the EGM2008 Gravity Field by Means of GPS Levelling and Sea Surface Topography Solutions  

Microsoft Academic Search

The new EGM2008 global gravity field model is evaluated by comparisons of geoid heights computed from the model with those available at GPS levelling stations in various regions and by computing sea surface topography solutions from the difference between the mean sea surface and the geoid from this model. In order to identify how good the model performs the same

Thomas Gruber

2008-01-01

71

Combustion of Gaseous Fuels with High Temperature Air in Normal- and Micro-gravity Conditions  

NASA Technical Reports Server (NTRS)

The objective of this study is determine the effect of air preheat temperature on flame characteristics in normal and microgravity conditions. We have obtained qualitative (global flame features) and some quantitative information on the features of flames using high temperature combustion air under normal gravity conditions with propane and methane as the fuels. This data will be compared with the data under microgravity conditions. The specific focus under normal gravity conditions has been on determining the global flame features as well as the spatial distribution of OH, CH, and C2 from flames using high temperature combustion air at different equivalence ratio.

Wang, Y.; Gupta, A. K.

2001-01-01

72

Venus gravity  

NASA Technical Reports Server (NTRS)

The anomalous gravity field of Venus shows high correlation with surface features revealed by radar. We extract gravity models from the Doppler tracking data from the Pioneer Venus Orbiter (PVO) by means of a two-step process. In the first step, we solve the nonlinear spacecraft state estimation problem using a Kalman filter-smoother. The Kalman filter was evaluated through simulations. This evaluation and some unusual features of the filter are discussed. In the second step, we perform a geophysical inversion using a linear Bayesian estimator. To allow an unbiased comparison between gravity and topography, we use a simulation technique to smooth and distort the radar topographic data so as to yield maps having the same characteristics as our gravity maps. The maps presented cover 2/3 of the surface of Venus and display the strong topography-gravity correlation previously reported. The topography-gravity scatter plots show two distinct trends.

Reasenberg, Robert D.

1993-01-01

73

Very high level concurrent programming  

SciTech Connect

The MODEL approach reported in this paper allows human designers to have a nonprocedural implementation-independent view of a concurrent system. The designers specify the problem to be solved through representing problem concepts by variables and composing equations which define the variables. They partition the overall problem into modules, which are candidates for being computed concurrently. Each module consists of a subset of the equations. Excluded are such dynamic implementation concepts as sequences of program events, synchronization, exchanges of messages and relative timing. The translation from the specification into a respective computation by an object computer architecture is performed by the language processors. The methodology supports independence in specifying and testing individual modules. The language processors detect inconsistency and incompleteness errors in both the individual modules and in the global system. The automatic implementation of a specified system is performed by the MODEL system on two levels. On the global level, the Configurator accepts as input a graph of the network of subsystems, modules, and files and their interconnections. It verifies the validity of interfaces and implements the network by generating command language programs that set up communications, optimize concurrency of modules and oversee execution of the overall system. On the local level, the Compiler accepts as input an individual module specification. It performs checking of completeness and consistency of variables and equations and generates an optimized sequential program in a high level language. The overall methodology is described through the dining philosophers which represents resource allocation, widely used in operating systems and real-time systems. Brief description of the operation of the Configurator and the Compiler are also given.

Shi, Y.; Prywes, N.; Szymanski, B.; Pnueli, A.

1987-09-01

74

Could quantum gravity phenomenology be tested with high intensity lasers?  

NASA Astrophysics Data System (ADS)

In phenomenological quantum gravity theories, Planckian behavior is triggered by the energy of elementary particles approaching the Planck energy, EP, but it is also possible that anomalous behavior strikes systems of particles with total energy near EP. This is usually perceived to be pathological and has been labeled “the soccer ball problem.” We point out that there is no obvious contradiction with experiment if coherent collections of particles with bulk energy of order EP do indeed display Planckian behavior, a possibility that would open a new experimental window. Unfortunately, field theory realizations of “doubly” (or deformed) special relativity never exhibit a soccer ball problem; we present several formulations where this is undeniably true. Upon closer scrutiny we discover that the only chance for Planckian behavior to be triggered by large coherent energies involves the details of second quantization. We find a formulation where the quanta have their energy-momentum (mass-shell) relations deformed as a function of the bulk energy of the coherent packet to which they belong, rather than the frequency. Given ongoing developments in laser technology, such a possibility would be of great experimental interest.

Magueijo, João

2006-06-01

75

Non-Boussinesq axisymmetric gravity currents at high Re  

NASA Astrophysics Data System (ADS)

The propagation of a non-Boussinesq gravity current in an axisymmetric configuration (full cylinder or wedge) is considered. The current of density ?c is released from rest from a lock of radius r0 and height h0 into an ambient fluid of density ?a in a container of height H, adjacent to the horizontal boundary on which propagation occurs. When the Reynolds number Re is large, the resulting flow is governed by the parameters ?c/?a and H^* = H/h0. We show that the shallow-water one layer model, carefully combined with a Benjamin-type front condition, provides a versatile formulation for the thickness and speed of the current, for a wide range of the parameters, without any adjustable constants. (The Boussinesq currents are just a small subdomain about ?c/?a= 1 of this solution). Comparisons with Navier-Stokes solutions and differences with the 2D rectangular counterpart (Ungarish, J. Fluid Mech. 579, 373-382, 2007) are discussed.

Ungarish, Marius

2009-11-01

76

Very high gravity (VHG) ethanolic brewing and fermentation: a research update.  

PubMed

There have been numerous developments in ethanol fermentation technology since the beginning of the new millennium as ethanol has become an immediate viable alternative to fast-depleting crude reserves as well as increasing concerns over environmental pollution. Nowadays, although most research efforts are focused on the conversion of cheap cellulosic substrates to ethanol, methods that are cost-competitive with gasoline production are still lacking. At the same time, the ethanol industry has engaged in implementing potential energy-saving, productivity and efficiency-maximizing technologies in existing production methods to become more viable. Very high gravity (VHG) fermentation is an emerging, versatile one among such technologies offering great savings in process water and energy requirements through fermentation of higher concentrations of sugar substrate and, therefore, increased final ethanol concentration in the medium. The technology also allows increased fermentation efficiency, without major alterations to existing facilities, by efficient utilization of fermentor space and elimination of known losses. This comprehensive research update on VHG technology is presented in two main sections, namely VHG brewing, wherein the effects of nutrients supplementation, yeast pitching rate, flavour compound synthesis and foam stability under increased wort gravities are discussed; and VHG bioethanol fermentation studies. In the latter section, aspects related to the role of osmoprotectants and nutrients in yeast stress reduction, substrates utilized/tested so far, including saccharide (glucose, sucrose, molasses, etc.) and starchy materials (wheat, corn, barley, oats, etc.), and mash viscosity issues in VHG bioethanol production are detailed. Thereafter, topics common to both areas such as process optimization studies, mutants and gene level studies, immobilized yeast applications, temperature effect, reserve carbohydrates profile in yeast, and economic aspects are discussed and future prospects are summarized. PMID:21695540

Puligundla, Pradeep; Smogrovicova, Daniela; Obulam, Vijaya Sarathi Reddy; Ko, Sanghoon

2011-09-01

77

High gravity and high cell density mitigate some of the fermentation inhibitory effects of softwood hydrolysates  

PubMed Central

After steam pretreatment of lignocellulosic substrates the fermentation of the biomass derived sugars to ethanol is typically problematic because of both the generally low sugar concentrations that can be supplied and the presence of naturally occurring and process derived inhibitors. As the majority of the inhibitory materials are usually associated with the hemicellulose rich, water soluble component, this fraction was supplemented with glucose to simulate high solids, un-detoxified substrate to see if a high gravity/high cell consistency approach might better cope with inhibition. Several yeast strains were assessed, with the Tembec T1, T2 and Lallemand LYCC 6469 strains showing the greatest ethanol productivity and yield. The addition of supplemental glucose enabled the faster and quantitatively higher removal of hydroxymethylfurfural (HMF). High cell density could provide effective fermentation at high sugar concentrations while enhancing inhibitor reduction. A 77% ethanol yield could be achieved using strain LYCC 6469 after 48 h at high cell density. It was apparent that a high cell density approach improved ethanol production by all of the evaluated yeast strains.

2013-01-01

78

Evaluation of EGM2008 Earth Gravitational Model in Algeria using gravity and GPS/levelling data  

NASA Astrophysics Data System (ADS)

The present work focuses on the evaluation of the EGM2008 geopotential model that was recently released by the NGA (National Geospatial-Intelligence Agency, U.S)/EGM-development team, in Algeria using the free air gravity anomalies supplied by BGI and GETECH, some of the precise GPS data collected from the international TYRGEONET (TYRhenian GEOdynamical NETwork) and ALGEONET (ALGerian GEOdynamical NETwork) projects and the last Algerian local gravimetric geoid model. Additional comparisons of the terrestrial point data with the corresponding values obtained from other geopotential models were made. Five global geopotential models were used in this comparison: the Preliminary Earth Gravitational Model PGM2007A, the combined CHAMP and GRACE model EIGEN-CG01C, the combined GRACE and LAGEOS model EIGEN-GL04C, OSU91A and EGM96. The study shows that all tested models are an improvement over OSU91A geopotential model used in all previous Algerian geoid computations and that new released combined model (EGM2008) is relatively superior to other tested models in the Algerian region. According to our numerical results, the new EGM2008 model fits better the observed values used in this investigation. Its standard deviations fit with GPS/levelling data are 21.4cm and 18.7cm before and after fitting using four-parameters transformation model. We strongly recommend the use of this new model in the remove-restore technique for the computation of the improved geoid for Algeria. In addition to these more general investigations, special GPS campaign has been performed for altimetric auscultation of a storage tank in which we wanted to test the possibilities to replace levelling by GPS measurements. The evaluation revealed promising results but also that much attention has to be paid on the GPS evaluation method. Key words: Geopotential model, TYRGEONET and ALGEONET projects, GPS/levelling data.

Benahmed Daho, S. A.

2009-04-01

79

Wafer-Level Integration Technique of Surface Mount Devices on a Si-Wafer With Vibration Energy and Gravity Force  

Microsoft Academic Search

This paper reports about a novel wafer-level integration technique of discrete surface mount devices (SMDs). It enables wafer-level mounting of plural kinds of SMDs on a silicon (Si)-wafer using vibration and gravity force. Deep holes with 400-m depth are formed on the surface of a Si-wafer by deep reactive ion etching process after general integrated circuit process for positioning of

Minoru Sudou; Hidekuni Takao; Kazuaki Sawada; Makoto Ishida

2007-01-01

80

Local geoid determination combining gravity disturbances and GPS\\/levelling: a case study in the Lake Nasser area, Aswan, Egypt  

Microsoft Academic Search

.  ?The use of GPS for height control in an area with existing levelling data requires the determination of a local geoid and\\u000a the bias between the local levelling datum and the one implicitly defined when computing the local geoid. If only scarse gravity\\u000a data are available, the heights of new data may be collected rapidly by determining the ellipsoidal height

C. C. Tscherning; Awar Radwan; A. A. Tealeb; S. M. Mahmoud; M. Abd El-Monum; Ramdan Hassan; I. El-Syaed; K. Saker

2001-01-01

81

Comparison of Techniques for the Computation of a Height Reference Surface from Gravity and GPS-Levelling Data  

Microsoft Academic Search

Three different techniques for quasigeoid modelling from gravity and GPS-levelling data are compared: (i) a penalized least-squares\\u000a technique using spherical radial basis functions provides a gravimetric quasigeoid solution; the combination with GPS-levelling\\u000a data is formulated as the solution of a Cauchy boundary-value problem for the Laplace operator. This solution when added to\\u000a gravimetric solution yields the final quasigeoid; (ii) a

R. Tenzer; R. Klees; I. Prutkin; T. Wittwer; B. Alberts; U. Schirmer; J. Ihde; G. Liebsch; U Schäfer

82

On the recovery of gravity anomalies from high precision altimeter data  

NASA Technical Reports Server (NTRS)

A model for the recovery of gravity anomalies from high precision altimeter data is derived which consists of small correction terms to the inverse Stokes' formula. The influence of unknown sea surface topography in the case of meandering currents such as the Gulf Stream is discussed. A formula was derived in order to estimate the accuracy of the gravity anomalies from the known accuracy of the altimeter data. It is shown that for the case of known harmonic coefficients of lower order the range of integration in Stokes inverse formula can be reduced very much.

Lelgemann, D.

1976-01-01

83

Global estimates of gravity wave momentum flux from High Resolution Dynamics Limb Sounder observations  

Microsoft Academic Search

High Resolution Dynamics Limb Sounder (HIRDLS) temperature profiles are analyzed to derive global properties of gravity waves. We describe a wavelet analysis technique that determines covarying wave temperature amplitude in adjacent temperature profile pairs, the wave vertical wavelength as a function of height, and the horizontal wave number along the line joining each profile pair. The analysis allows a local

M. J. Alexander; J. Gille; C. Cavanaugh; M. Coffey; C. Craig; T. Eden; G. Francis; C. Halvorson; J. Hannigan; R. Khosravi; D. Kinnison; H. Lee; S. Massie; B. Nardi; J. Barnett; C. Hepplewhite; A. Lambert; V. Dean

2008-01-01

84

Study of the high-frequency spectrum of the anomalous gravity potential  

Microsoft Academic Search

The analysis of the high-frequency spectrum of the anomalous gravity potential is important for a number of current and emerging technologies in geodesy and geophysics. Among them is the precise determination of deflections of the vertical by inertial techniques, the development of data processing methods in airborne gradiomery, and the signal extraction methods for airborne gravimetry. The spectral information required

A. A. Vassiliou; K. P. Schwarz

1987-01-01

85

High-resolution numerical simulations of resuspending gravity currents: Conditions for self-sustainment  

Microsoft Academic Search

We introduce a computational model for high-resolution simulations of particle-laden gravity currents. The features of the computational model are described in detail, and validation data are discussed. Physical results are presented that focus on the influence of particle entrainment from the underlying bed. As turbulent motions detach particles from the bottom surface, resuspended particles entrained over the entire length of

F. Blanchette; M. Strauss; E. Meiburg; B. Kneller; M. E. Glinsky

2005-01-01

86

Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions?  

PubMed Central

To save energy, space, and time, today's breweries make use of high-gravity brewing in which concentrated medium (wort) is fermented, resulting in a product with higher ethanol content. After fermentation, the product is diluted to obtain beer with the desired alcohol content. While economically desirable, the use of wort with an even higher sugar concentration is limited by the inability of brewer's yeast (Saccharomyces pastorianus) to efficiently ferment such concentrated medium. Here, we describe a successful strategy to obtain yeast variants with significantly improved fermentation capacity under high-gravity conditions. We isolated better-performing variants of the industrial lager strain CMBS33 by subjecting a pool of UV-induced variants to consecutive rounds of fermentation in very-high-gravity wort (>22° Plato). Two variants (GT336 and GT344) showing faster fermentation rates and/or more-complete attenuation as well as improved viability under high ethanol conditions were identified. The variants displayed the same advantages in a pilot-scale stirred fermenter under high-gravity conditions at 11°C. Microarray analysis identified several genes whose altered expression may be responsible for the superior performance of the variants. The role of some of these candidate genes was confirmed by genetic transformation. Our study shows that proper selection conditions allow the isolation of variants of commercial brewer's yeast with superior fermentation characteristics. Moreover, it is the first study to identify genes that affect fermentation performance under high-gravity conditions. The results are of interest to the beer and bioethanol industries, where the use of more-concentrated medium is economically advantageous.

Blieck, Lies; Toye, Geert; Dumortier, Francoise; Verstrepen, Kevin J.; Delvaux, Freddy R.; Thevelein, Johan M.; Van Dijck, Patrick

2007-01-01

87

Cell recycling during repeated very high gravity bio-ethanol fermentations using the industrial Saccharomyces cerevisiae strain PE-2.  

PubMed

A very high gravity (VHG) repeated-batch fermentation system using an industrial strain of Saccharomyces cerevisiae PE-2 (isolated from sugarcane-to-ethanol distillery in Brazil) and mimicking industrially relevant conditions (high inoculation rates and low O(2) availability) was successfully operated during fifteen consecutive fermentation cycles, attaining ethanol at 17.1 ± 0.2% (v/v) with a batch productivity of 3.5 ± 0.04 g l(-1) h(-1). Moreover, this innovative operational strategy (biomass refreshing step) prevented critical decreases on yeast viability levels and promoted high accumulation of intracellular glycerol and trehalose, which can provide an adaptive advantage to yeast cells under harsh industrial environments. This study contributes to the improvement of VHG fermentation processes by exploring an innovative operational strategy that allows attaining very high ethanol titres without a critical decrease of the viability level thus minimizing the production costs due to energy savings during the distillation process. PMID:21898130

Pereira, Francisco B; Gomes, Daniel G; Guimarães, Pedro M R; Teixeira, José A; Domingues, Lucília

2012-01-01

88

Quantum gravity  

NASA Astrophysics Data System (ADS)

Quantum Gravity is the name given to any theory that describes gravity in the regimes where quantum effects cannot be disregarded. At present, there is no such a theory which is universally accepted and confirmed by experience. Therefore the term "Quantum Gravity" indicates more an open problem than a specific theory. Several research lines, at different levels of development, offer tentative solutions to the problem. These tentative quantum-gravity theories are variously viewed as competing research directions, or as contributions to the common goal of finding the physically correct theory. The quest for the good quantum theory of gravity bears on a number of fundamental issues and it is sometimes presented as the most important open problem in fundamental physics: the "Holy Grail" of contemporary theoretical physics.

Rovelli, Carlo

2008-05-01

89

Bathymetry of Patagonia glacier fjords and glacier ice thickness from high-resolution airborne gravity combined with other data  

NASA Astrophysics Data System (ADS)

The North and South Patagonia Ice fields are the largest ice masses outside Antarctica in the Southern Hemisphere. During the period 1995-2000, these glaciers lost ice at a rate equivalent to a sea level rise of 0.105 ± 0.001 mm/yr. In more recent years, the glaciers have been thinning more quickly than can be explained by warmer air temperatures and decreased precipitation. A possible cause is an increase in flow speed due to enhanced ablation of the submerged glacier fronts. To understand the dynamics of these glaciers and how they change with time, it is critical to have a detailed view of their ice thickness, the depth of the glacier bed below sea or lake level, how far inland these glaciers remain below sea or lake level, and whether bumps or hollows in the bed may slow down or accelerate their retreat. A grid of free-air gravity data over the Patagonia Glaciers was collected in May 2012 and October 2012, funded by the Gordon and Betty Moore Foundation (GBMF) to measure ice thickness and sea floor bathymetry. This survey combines the Sander Geophysics Limited (SGL) AIRGrav system, SGL laser altimetry and Chilean CECS/UCI ANDREA-2 radar. To obtain high-resolution and high-precision gravity data, the helicopter operates at 50 knots (25.7 m/s) with a grid spacing of 400m and collects gravity data at sub mGal level (1 Gal =1 Galileo = 1 cm/s2) near glacier fronts. We use data from the May 2012 survey to derive preliminarily high-resolution, high-precision thickness estimates and bathymetry maps of Jorge Montt Glacier and San Rafael Glacier. Boat bathymetry data is used to optimize the inversion of gravity over water and radar-derived thickness over glacier ice. The bathymetry maps will provide a breakthrough in our knowledge of the ice fields and enable a new era of glacier modeling and understanding that is not possible at present because ice thickness is not known.

An, L.; Rignot, E.; Rivera, A.; Bunetta, M.

2012-12-01

90

Prospects for a Gradiometry Mission for High-Resolution Mapping of Planetary Gravity Fields  

NASA Astrophysics Data System (ADS)

A promising technique to greatly improve the resolution and accuracy of gravity field models for Mars and other planets and moons is planetary satellite gravity gradiometry. The first satellite gradiometer ever will fly on- board the Earth orbiting GOCE mission, to be launched in 2007. For a planetary mission, a GOCE-like gradiometer instrument is much too large and too heavy. Highly miniaturized instrumentation is a prerequisite in order to realize a planetary gradiometer mission. A novel technique for a so-called micro-gradiometer is currently being developed in the Netherlands. This micro-gradiometer is based on MEMS technology in combination with miniaturized and high-performance read-out and control electronics. This paper addresses these technological developments. A case study for Mars is shown of predicted improvements in gravity field models that are to be obtained with a micro-gradiometer mission. New gravity field models from a gradiometer mission will greatly improve our understanding of the interior of planets and of their evolution.

Koop, R.; Smit, M.; Haanstra, J.; Bouman, J.; Selig, A.; Flokstra, J.; Cuperus, R.; Wiegerink, R.; Visser, P.; Vermeersen, B.; Berg, A. V.

2006-12-01

91

Prospects for a Gradiometry Mission for High-Resolution Mapping of the Martian Gravity Field  

NASA Astrophysics Data System (ADS)

Nowadays knowledge of the Martian gravity field has been obtained from a combination of line-of-sight radio tracking of planetary orbiters and topography information from altimeters on board some of these orbiters. A promising technique to greatly improve the resolution and accuracy of gravity field models for Mars (and possibly other planets and moons) is planetary satellite gravity gradiometry. The first satellite gradiometer ever will fly on-board the Earth orbiting GOCE mission, to be launched in 2007. For a planetary mission to Mars, a GOCE-like gradiometer instrument is much too large and too heavy. Highly miniaturized instrumentation is a prerequisite in order to realize a planetary gradiometer mission. A novel technique for a so-called micro-gradiometer is currently being developed in the Netherlands. This micro-gradiometer is based on MEMS technology in combination with miniaturized and high-performance read-out and control electronics. This paper addresses these technological developments as well as the predicted improvements in gravity field models for Mars that are to be obtained with a micro-gradiometer mission. Such new models will greatly improve our understanding of the interior of Mars and of its evolution.

Koop, R.; Smit, M.; Zegers, T.; Bouman, J.; Selig, A.; Flokstra, J.; Cuperus, R.; Vermeersen, B.; Visser, P.; van den Berg, A.

92

GTOOLS: an Interactive Computer Program to Process Gravity Data for High-Resolution Applications  

NASA Astrophysics Data System (ADS)

An interactive computer program, GTOOLS, has been developed to process gravity data acquired by the Scintrex CG-5 and LaCoste & Romberg EG, G and D gravity meters. The aim of GTOOLS is to provide a validated methodology for computing relative gravity values in a consistent way accounting for as many environmental factors as possible (e.g., tides, ocean loading, solar constraints, etc.), as well as instrument drift. The program has a modular architecture. Each processing step is implemented in a tool (function) that can be either run independently or within an automated task. The tools allow the user to (a) read the gravity data acquired during field surveys completed using different types of gravity meters; (b) compute Earth tides using an improved version of Longman's (1959) model; (c) compute ocean loading using the HARDISP code by Petit and Luzum (2010) and ocean loading harmonics from the TPXO7.2 ocean tide model; (d) estimate the instrument drift using linear functions as appropriate; and (e) compute the weighted least-square-adjusted gravity values and their errors. The corrections are performed up to microGal ( ?Gal) precision, in accordance with the specifications of high-resolution surveys. The program has the ability to incorporate calibration factors that allow for surveys done using different gravimeters to be compared. Two additional tools (functions) allow the user to (1) estimate the instrument calibration factor by processing data collected by a gravimeter on a calibration range; (2) plot gravity time-series at a chosen benchmark. The interactive procedures and the program output (jpeg plots and text files) have been designed to ease data handling and archiving, to provide useful information for future data interpretation or modeling, and facilitate comparison of gravity surveys conducted at different times. All formulas have been checked for typographical errors in the original reference. GTOOLS, developed using Matlab, is open source and machine independent. We will demonstrate program use and utility with data from multiple microgravity surveys at Kilauea volcano, Hawai'i.

Battaglia, M.; Poland, M. P.; Kauahikaua, J. P.

2012-12-01

93

Optimizing High Level Waste Disposal  

SciTech Connect

If society is ever to reap the potential benefits of nuclear energy, technologists must close the fuel-cycle completely. A closed cycle equates to a continued supply of fuel and safe reactors, but also reliable and comprehensive closure of waste issues. High level waste (HLW) disposal in borosilicate glass (BSG) is based on 1970s era evaluations. This host matrix is very adaptable to sequestering a wide variety of radionuclides found in raffinates from spent fuel reprocessing. However, it is now known that the current system is far from optimal for disposal of the diverse HLW streams, and proven alternatives are available to reduce costs by billions of dollars. The basis for HLW disposal should be reassessed to consider extensive waste form and process technology research and development efforts, which have been conducted by the United States Department of Energy (USDOE), international agencies and the private sector. Matching the waste form to the waste chemistry and using currently available technology could increase the waste content in waste forms to 50% or more and double processing rates. Optimization of the HLW disposal system would accelerate HLW disposition and increase repository capacity. This does not necessarily require developing new waste forms, the emphasis should be on qualifying existing matrices to demonstrate protection equal to or better than the baseline glass performance. Also, this proposed effort does not necessarily require developing new technology concepts. The emphasis is on demonstrating existing technology that is clearly better (reliability, productivity, cost) than current technology, and justifying its use in future facilities or retrofitted facilities. Higher waste processing and disposal efficiency can be realized by performing the engineering analyses and trade-studies necessary to select the most efficient methods for processing the full spectrum of wastes across the nuclear complex. This paper will describe technologies being evaluated at Idaho National Laboratory and the facilities we’ve designed to evaluate options and support optimization.

Dirk Gombert

2005-09-01

94

Concurrent Research on High Gravity (G) Combustion and Enabling Materials.  

National Technical Information Service (NTIS)

This is a joint program between MLLN and PRTS. Fundamental combustion and materials science issues are being investigated that will lead to the development of a revolutionary propulsion system that operates on a highly efficient near-constant temperature ...

R. J. Kerans W. M. Roquemore

2001-01-01

95

High-Latitude Gravity Wave Measurements in Noctilucent Clouds and Polar Mesospheric Clouds  

Microsoft Academic Search

\\u000a Distinct wave forms traditionally observed in Noctilucent Cloud (NLC) photographs and most recently captured in high-resolution\\u000a panoramic images of Polar Mesospheric Clouds (PMC) provide an exceptionally rich resource for quantifying gravity wave activity\\u000a and properties in the high-latitude summer mesopause region. Using extensive image data on PMC structures obtained by the\\u000a Cloud Imaging and Particle Size (CIPS) ultraviolet instrument onboard

Michael J. Taylor; P.-D. Pautet; Y. Zhao; C. E. Randall; J. Lumpe; S. M. Bailey; J. Carstens; K. Nielsen; James M. Russell; J. Stegman

96

High-resolution numerical modeling of wave-supported gravity-driven mudflows  

NASA Astrophysics Data System (ADS)

Wave-supported gravity-driven mudflow has been identified as a major offshore fine sediment transport mechanism of terrestrial sediment into the coastal ocean. This transport process essentially occurs within the wave boundary layer. In this study, wave-supported gravity-driven mudflow is investigated via a wave-phase-resolving high-resolution numerical model for fluid mud transport. The model results are verified with field observation of sediment concentration and near-bed flow velocities at Po prodelta. The characteristics of wave-supported gravity-driven mudflows are diagnosed by varying the bed erodibility, floc properties (fractal dimension), and rheological stresses in the numerical simulations. Model results for moderate concentration suggest that using an appropriately specified fractal dimension, the dynamics of wave-supported gravity-driven mudflow can be predicted without explicitly incorporating rheological stress. However, incorporating rheological stress makes the results less sensitive to prescribed fractal dimension. For high-concentration conditions, it is necessary to incorporate rheological stress in order to match observed intensity of downslope gravity-driven current. Model results are further analyzed to evaluate and calibrate simple parameterizations. Analysis suggests that when neglecting rheological stress, the drag coefficient decreases with increasing wave intensity and seems to follow a power law. However, when rheological stress is incorporated, the resulting drag coefficient is more or less constant (around 0.0013) for different wave intensities. Model results further suggest the bulk Richardson number has a magnitude smaller than 0.25 and is essentially determined by the amount of available soft mud (i.e., the erodibility), suggesting a supply limited condition for unconsolidated mud.

Hsu, Tian-Jian; Ozdemir, Celalettin E.; Traykovski, Peter A.

2009-05-01

97

Exploration of Anomalous Gravity Effects by rf-Pumped Magnetized High-T(c) Superconducting Oxides  

NASA Technical Reports Server (NTRS)

A number of anomalous gravitational effects have been reported in the scientific literature during recent years, but there has been no independent confirmation with regard to any of these claims. Therefore, the NASA Marshall Space Flight Center, in response to the propulsion challenges specified by NASA's Breakthrough Propulsion Physics (BPP) program, proposed to explore the possibility of observing anomalous gravitation behavior through the manipulation of Josephson junction effects in magnetized high-Tc superconducting oxides. The technical goal was to critically test this revolutionary physical claim and provide a rigorous, independent, empirical confirmation (or refutation) of anomalous effects related to the manipulation of gravity by radio frequency (rf)-pumped magnetized type-2 superconductors. Because the current empirical evidence for gravity modification is anecdotal, our objective was to design, construct, and meticulously implement a discriminating experiment, which would put these observations on a more firm footing within the scientific community. Our approach is unique in that we advocate the construction of an extremely sensitive torsion balance with which to measure gravity modification effects by rf-pumped type-2 superconductor test masses. This paper reviews the anecdotal evidence for anomalous gravity effects, describes the design and development of a simplified torsion balance experiment for empirically investigating these claims, and presents the results of preliminary experiments.

Robertson, Tony; Litchford, Ron; Peters, Randall; Thompson, Byran; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

98

Improving GOMOS High Resolution Temperature validation by discriminating atmospheric gravity waves  

NASA Astrophysics Data System (ADS)

Atmospheric gravity waves play an important role in the thermodynamic processes of the atmosphere. The gravity waves, once generated in the upper troposphere and lower stratosphere, propagate upward and deposit their energy and momentum when dissipating. These atmospheric waves can cause strong fluctuations in the thermal structure of the middle and upper atmosphere. The satellite temperature retrievals, together with innovative analysis methods, are often used to provide constraints for model parameterization, which can improve the treatment of these phenomena in climate-prediction models, as the temperature profiles are expected to present wave-like structures due to the global distribution of the gravity-wave momentum flux. The analysis of temperature variability as a function of spatial and temporal separation indicates that gravity wave activity has impacts also on validation study site selection. The aim of this study is to analyse the characteristics of the atmospheric gravity waves detectable in the GOMOS (Global Ozone Monitoring by Occultation of Stars) High Resolution Temperature Profiles (HRTP). These are collected over altitudes ranging from 18 to 35 km, in the 2002 to 2012 time period. The GOMOS instrument is a medium-resolution star-occultation spectrometer operating in the ultraviolet-visible-near-infrared (UV-VIS-NIR) spectral range, onboard of the ESA/ENVISAT platform. The HRTP products are the result of the analysis of the two fast photometer measurements, and the retrieval is based on a GPS-like inversion scheme (Kyrola et al., 2010). Following our new approach, based on the use of the "Morlet" wavelet transform (Torrence and Compo, 1998), it is possible to capture the vertical amplitude and phase of waves of very different size along the temperature profile. The wavy signal is estimated and subtracted to the original profile, thus providing a "wave-free" profile. Comparison of wave-free temperature profiles and gravity wave structures with those estimated from collocated ozonesonde data (SHADOZ, http://croc.gsfc.nasa.gov/shadoz) in the 40S to 40N latitude range will be discussed in detail. Preliminary results demonstrate that the proposed approach is very effective, particularly for the study of gravity waves, which are by nature non stationary and highly localised in space and time. References -E. Kyrölä, J. Tamminen, V. Sofieva, J. L. Bertaux, A. Hauchecorne, F. Dalaudier, D. Fussen, F. Vanhellemont, O. Fanton d'Andon, G. Barrot, M. Guirlet, A. Mangin, L. Blanot, T. Fehr, L. Saavedra de Miguel, and R. Fraisse, 2010: "Retrieval of atmospheric parameters from GOMOS data" Atmos. Chem. Phys., 10, 11881-11903, 2010 -Torrence, C. and G. P. Compo, 1998: "A Practical Guide to Wavelet Analysis". Bull. Amer. Meteor. Soc., 79, 61-78

Quirino Iannone, Rosario; Casadio, Stefano; Saavedra de Miguel, Lidia; De Laurentis, Marta; Brizzi, Gabriele; Dehn, Angelika

2013-04-01

99

Development of high accuracy and resolution geoid and gravity maps  

NASA Technical Reports Server (NTRS)

Precision satellite to satellite tracking can be used to obtain high precision and resolution maps of the geoid. A method is demonstrated to use data in a limited region to map the geopotential at the satellite altitude. An inverse method is used to downward continue the potential to the Earth surface. The method is designed for both satellites in the same low orbit.

Gaposchkin, E. M.

1986-01-01

100

Gravity gradiometry on high-T{sub c} superconducting sensors  

SciTech Connect

This is the final report of a 1-y LDRD project at LANL. Earth`s gravitational field has minuscule local variations that are difficult to observe with any but the most sensitive instruments. These variations are caused by local variations in the earth`s crust density such as voids or high density material. Such anomalies can be observed directly by mapping the magnitude of the gravitational field (gravimetry) or by measuring the gradient of the gravitational field (gradiometry). It is believed that gradiometry is potentially superior to gravimetry because measurement and interpretation is simpler and less susceptible to masking by other effects, e.g. accelerations. This method introduces no energy or radiation into the region of interest, can be adapted to moving platforms and the capability to take real-time data over large areas is feasible. Scope of this work was to examine feasiiblity and performance of a fieldable gradiometer using high-{Tc} materials.

Kraus, R.; Cogbill, A.; Stettler, M.

1996-09-01

101

Internal gravity waves in the thermosphere during low and high solar activity: Simulation study  

NASA Astrophysics Data System (ADS)

Propagation of internal gravity waves (GWs) from the lower atmosphere into the upper thermosphere, and their dynamical and thermal effects have been studied under low and high solar activity approximated by the F10.7 parameter. It has been done by using a nonlinear spectral parameterization in systematic offline calculations with typical wind and temperature distributions from the HWM and MSISE-90 models, and with interactive simulations using the University College London Coupled Middle Atmosphere-Thermosphere-2 (CMAT2) general circulation model (GCM) under solstice conditions. The estimates have been performed for relatively slow harmonics with horizontal phase velocities less than 100 m s-1, which are not affected by back reflection and/or ducting. GW drag and wave-induced heating/cooling are shown to be smaller below ~170 km at high solar activity, and larger above. The maxima of GW momentum deposition occur much higher in the upper thermosphere, but their peaks are twice as weak, 120 vs 240 m s-1 d-1, in the winter hemisphere when the insolation is large. Instead of strong net cooling in the upper thermosphere, GWs produce a weak heating at high solar activity created by fast harmonics less affected by dissipation. Molecular diffusion increases with solar activity at fixed pressure levels, but seen in a Cartesian altitude grid it can show increasing and decreasing tendencies in the lower thermosphere with respect to low solar activity. Therefore, in pressure coordinates, in which most of GCMs operate, the influence of larger temperatures can be viewed as a competition between the enhanced dissipation and vertical expansion of the atmosphere.

Yi?it, Erdal; Medvedev, Alexander S.

2010-05-01

102

Internal gravity waves in the thermosphere during low and high solar activity: Simulation study  

NASA Astrophysics Data System (ADS)

Propagation of internal gravity waves (GWs) from the lower atmosphere into the upper thermosphere, and their dynamical and thermal effects have been studied under low and high solar activity approximated by the F10.7 parameter. It has been done by using a nonlinear spectral parameterization in systematic offline calculations with typical wind and temperature distributions from the HWM and MSISE-90 models, and with interactive simulations using the University College London Coupled Middle Atmosphere-Thermosphere-2 (CMAT2) general circulation model (GCM) under solstice conditions. The estimates have been performed for relatively slow harmonics with horizontal phase velocities less than 100 m s-1, which are not affected by reflection and/or ducting. GW drag and wave-induced heating/cooling are shown to be smaller below ˜170 km at high solar activity, and larger above. The maxima of GW momentum deposition occur much higher in the upper thermosphere, but their peaks are half as strong, 120 vs 240 m s-1 day-1 in the winter hemisphere when the insolation is large. Instead of strong net cooling in the upper thermosphere, GWs produce a weak heating at high solar activity created by fast harmonics less affected by dissipation. Molecular viscosity increases with solar activity at fixed pressure levels, but seen in Cartesian altitude grids it can either increase or decrease in the lower thermosphere, depending on the height. Therefore, in pressure coordinates, in which most GCMs operate, the influence of larger temperatures can be viewed as a competition between the enhanced dissipation and vertical expansion of the atmosphere.

Yi?it, Erdal; Medvedev, Alexander S.

2010-08-01

103

High temperature liquid level sensor  

DOEpatents

A length of metal sheathed metal oxide cable is perforated to permit liquid access to the insulation about a pair of conductors spaced close to one another. Changes in resistance across the conductors will be a function of liquid level, since the wetted insulation will have greater electrical conductivity than that of the dry insulation above the liquid elevation.

Tokarz, Richard D. (West Richland, WA)

1983-01-01

104

Mass changes at different levels revealed by micro-gravity and deformation measurements at Kilauea Volcano, Hawai'i. (Invited)  

NASA Astrophysics Data System (ADS)

Using campaign micro-gravity measurements collected at Kilauea Volcano, Hawai'i (United States), between December 2009 and November 2012, we document significant mass variations at the summit of the volcano. These variations produce a maximum residual gravity change of +370 × 14 ?Gal near the east margin of Halema'uma'u Crater, within Kilauea's summit caldera, where in March 2008 a new eruptive vent opened. This vent has progressively enlarged through several collapses and now forms a 210x160 m elliptical cavity that is currently occupied by a lava lake whose surface fluctuates between 25 and 200 meters below the vent rim. Five micro-gravity surveys were performed using two Scintrex CG-5 gravimeters. Each survey was completed following a double-looping procedure, and each measurement was corrected for earth-tides, ocean loading, and instrument drift. Gravity changes at each station were then corrected for the free-air effect using vertical displacements calculated from combined ascending and descending InSAR measurements. InSAR data are from both the German Space Agency (DLR) TerraSAR-X satellite and the Italian Space Agency (ASI) Cosmo-SkyMed satellite-constellation. The spatial distribution of the gravity changes suggests that they are predominantly caused by the enlargement of the vent and variations in the height of the summit lava lake. The contribution to the gravity measurements caused by changes in lava level within the conduit feeding the lava lake is therefore estimated using a numerical model that takes into account its geometry, as inferred from visual and remotely sensed (LiDAR) observations, and lava height at the time of each gravity survey, determined from thermal camera data. These results can be used to make inferences on the density of the magma filling the lava lake, which we compare to values obtained using independent data from continuous gravimeters located near the campaign stations. Estimates of the lava level effect on the gravity allow us to compensate for it and assess changes measured across Kilauea's summit that may be due to mass variations caused by subsurface magma accumulation or withdrawal. We observe that a positive anomaly (which magnitude varies depending on the density of the material used for the fluid filling the lava lake) is still present after this correction in the 20-month-long period following the March 5-9, 2011, east rift zone (ERZ) fissure eruption. InSAR data spanning the same interval show that these positive changes are associated with uplift of the summit area, which we model as the inflation of a shallow magma reservoir at ~1.5 km depth. The contemporary increase in volume, inferred from the deformation data, and in mass, inferred from the micro-gravity measurement, suggest that, after the 2011 ERZ fissure eruption, magma has been accumulating beneath the summit of Kilauea.

Bagnardi, M.; Poland, M. P.; Battaglia, M.; Carbone, D.; Baker, S.; Amelung, F.

2013-12-01

105

Orbital Gravity Gradiometry Beyond GOCE: Geophysical Applications  

Microsoft Academic Search

We examine scientific applications of time-variable high-resolution global gravity field solutions anticipated from the multi-year gravity mission with the advanced superconducting gravity gradiometer (SGG). By virtue of the improved technology including cryogenics, the anticipated noise level of the SGG is 0.01 mE\\/&surd;Hz at the measurement bandwidth of 0.5 mHz to 0.1 Hz (300 times more precise over a wider frequency

H. Paik; M. V. Moody; K. Y. Venkateswara; S. Han; P. Ditmar; R. Klees; P. J. Shirron; M. J. Dipirro; E. R. Canavan; C. Jekeli; C. Shum

2010-01-01

106

Numerical Simulation of Phase Change at High Hydrostatic Pressure under Variable-Gravity Environment  

Microsoft Academic Search

We present a numerical investigation of phase change of water at high hydrostatic pressure conditions occurring under a gravitational environment and a low-gravity environment. A computational model consists of conservation equations of mass, momentum, and energy. Phase-transition phenomena are modeled with an enthalpy–porosity approach. Numerical solutions are obtained for process stages dominated by free convection as well as by forced

W. Kowalczyk; A. Delgado

2007-01-01

107

Evaluation of EGM2008 Earth Gravitational Model in Algeria using gravity and GPS\\/levelling data  

Microsoft Academic Search

The present work focuses on the evaluation of the EGM2008 geopotential model that was recently released by the NGA (National Geospatial-Intelligence Agency, U.S)\\/EGM-development team, in Algeria using the free air gravity anomalies supplied by BGI and GETECH, some of the precise GPS data collected from the international TYRGEONET (TYRhenian GEOdynamical NETwork) and ALGEONET (ALGerian GEOdynamical NETwork) projects and the last

S. A. Benahmed Daho

2009-01-01

108

Synchronous absolute EIT in three thoracic planes at different gravity levels  

NASA Astrophysics Data System (ADS)

The validity of absolute Electrical Impedance Tomography (a-EIT) for assessment of local lung volume has been investigated far less than the well evaluated ventilation monitoring by functional EIT (f-EIT). To achieve progress in a-EIT we investigated 10 healthy volunteers in an upright sitting position by using a-EIT at normal gravity (1 g), weightlessness (0 g) and approx. double gravity (1.8 g) during parabolic flight manoeuvres. Lung resistivity in three thoracic planes was determined by a-EIT using a multiple-plane synchronised Goe-MF II EIT system. Tomograms of resistivity at end-expiration in normal spontaneous breathing were reconstructed by a modified SIRT algorithm. Local lung resistivity was determined separately for both lungs. The respective resistivity values at 1 g and 1.8 g before and after weightlessness show an almost reversible behaviour along the sequence of gravity changes with a tendency to be lower after occurrence of weightlessness. The results reveal not only the expected varying resistivity of lung tissue in cranio-caudal direction but also a clear difference in these cranio-caudal stratifications of local lung volume between the left and right lung. The resolution and stability of absolute EIT seem to be valid and expressive for future investigations of unilateral lung volume under different physiological and pathological conditions.

Hahn, G.; Just, A.; Dittmar, J.; Fromm, K. H.; Quintel, M.

2013-04-01

109

Safety Analysis of High Hazard Deteriorating Concrete Gravity Dam-Reservoir Systems Including Corrective Measure - Earthquake and Dynamic Study.  

National Technical Information Service (NTIS)

Research was carried out to analyze the safety of high-hazard deteriorating concrete gravity dam-reservoir systems against earthquakes, using the Delaware Hoopes Dam as a model. Due to the uncertainty in earthquake occurance and magnitude, a probabilistic...

C. Y. Yang V. Chiarito P. Dressel

1981-01-01

110

On Gravity Reductions.  

National Technical Information Service (NTIS)

Bouguer's and isostatic methods for the evaluation of gravity anomalies on the earth's physical surface are discussed. Errors involved in the reduction of gravity down to sea level are compared for condensation, isostatic, and Rudzki's anomalies. The conn...

E. Groten

1964-01-01

111

High-Level Data Races  

NASA Technical Reports Server (NTRS)

Data races are a common problem in concurrent and multi-threaded programming. They are hard to detect without proper tool support. Despite the successful application of these tools, experience shows that the notion of data race is not powerful enough to capture certain types of inconsistencies occurring in practice. In this paper we investigate data races on a higher abstraction layer. This enables us to detect inconsistent uses of shared variables, even if no classical race condition occurs. For example, a data structure representing a coordinate pair may have to be treated atomically. By lifting the meaning of a data race to a higher level, such problems can now be covered. The paper defines the concepts view and view consistency to give a notation for this novel kind of property. It describes what kinds of errors can be detected with this new definition, and where its limitations are. It also gives a formal guideline for using data structures in a multi-threading environment.

Artho, Cyrille; Havelund, Klaus; Biere, Armin; Koga, Dennis (Technical Monitor)

2003-01-01

112

Satellite borne gravity gradiometer study  

NASA Technical Reports Server (NTRS)

Gravity gradiometry is recognized to be a very difficult instrumentation problem because extremely small differential acceleration levels have to be measured, 0.1 EU corresponds to an acceleration of 10 to the minus 11th power g at two points 1 meter apart. A feasibility model of a gravity gradiometer is being developed for airborne applications using four modified versions of the proven Model VII accelerometers mounted on a slowly rotating fixture. Gravity gradients are being measured to 1.07 EU in a vertical rotation axis orientation. Equally significant are the outstanding operational characteristics such as fast reaction time, low temperature coefficients and high degree of bias stability over long periods of time. The rotating accelerometer gravity gradiometer approach and its present status is discussed and it is the foundation for the orbital gravity gradiometer analyzed. The performance levels achieved in a 1 g environment of the earth and under relatively high seismic disturbances, lend the orbital gravity gradiometer a high confidence level of success.

Metzger, E.; Jircitano, A.; Affleck, C.

1976-01-01

113

Investigating asymmetries in mesospheric gravity wave propagation at high-latitudes  

NASA Astrophysics Data System (ADS)

A combination of ground based imaging of gravity waves in the mesospheric OH emission (peak altitude ~87 km) and satellite measurements of waves as detected in extensive polar mesospheric clouds, PMC's (mean altitude ~83 km) has been used to investigate summer-winter wave properties in both the Northern and Southern polar regions. Wintertime all-sky image data primarily from two sites (Halley and Rothera) on the Antarctic coast, obtained as part of a collaborative program with British Antarctic Survey, and from the Kjell Henriksen Observatory (KHO) Svalbard in the high Arctic, have been utilized to determine the dominant characteristics of both short and medium scale gravity waves (observed periods up to ~1 hour). These new results, which show distinct asymmetries in their propagation headings, are compared with recent summertime gravity wave measurements using PMC data from the Cloud Imaging and Particle Size (CIPS) experiment on the NASA Aeronomy of Ice in the Mesosphere (AIM) satellite. Our Southern Hemisphere results reveal novel evidence for strong preferences for zonal wave motions particularly for the smaller scale (<100 km horizontal wavelength) suggesting a significant pattern for meridional filtering throughout the Antarctic continent. In contrast, the medium-scale waves exhibited a consistent but quite different motion field. These new results are compared with recent Northern Hemisphere measurements to further investigate polar wave dynamics in the Mesosphere and Lower Thermosphere (MLT) region (~80-100 km).

Taylor, M. J.; Zhao, Y.; Ward, R.; Martin, T.; Pautet, P.; Dyrland, M. E.; Nielsen, K.; Jarvis, M. J.; Moffat-Griffin, T.; Randall, C. E.; Lumpe, J. D.; Bailey, S. M.; Russell, J. M.

2012-12-01

114

High-Level Transformations for DSP Synthesis.  

National Technical Information Service (NTIS)

This chapter reviews numerous high-level transformation techniques which can be applied at the algorithm or the architecture level to improve the performance of digital signal and image processing architectures and circuits implemented using VLSI technolo...

K. K. Parhi

1995-01-01

115

Observation and modeling of mesospheric Na density and OH airglow perturbations by a gravity wave approaching a critical level  

NASA Astrophysics Data System (ADS)

Atmospheric gravity waves at a broad range of temporal and spatial scales are frequently observed in MLT airglow imaging experiments. Airglow data provide significant insight into gravity wave propagation, directionality, and seasonality, and allow estimations of wave fluxes [e.g., Swenson et al., JGR, 104(D6), 1999]. The USU CEDAR Mesospheric Temperature Mapper (MTM) is a specialized CCD airglow imaging system, which was operated at Maui MALT from November 2001 to December 2006. The MTM captures OH(6,2) and O2(0,1) emissions intensities and associated rotational temperatures. The MTM is able to reveal two-dimensional structure of intensity and temperature perturbations associated with small-scale gravity waves, and has been used to assess zenith temperatures, showing close agreement with simultaneous lidar temperature data [Zhao et al., J. Geophys. Res., 110, D09S07, 2005]. Here we investigate the vertical and horizontal structure of a small-scale gravity wave (~18 minute period and ~37 km horizontal wavelength) captured by the Maui MTM on April 11, 2002. The event was strongly visible in the OH(6,2) image data, showing intensity perturbations ~ 5-10 %, however relatively weak in the O2 data. Lidar temperatures and winds suggest the presence of a critical level shortly above ~90 km, which would have contributed to increased dissipation, and reduced detectability, due to small vertical scale. With imaged intensity and rotational temperature data, along with evolving Na lidar profile data, we reconstruct and simulate the wave event under realistic ambient conditions using a suite of numerical models. Hydroxyl photochemistry and dynamics of O3, H, O, and Na densities are obtained with a two-dimensional nonlinear numerical model for gravity wave dynamics [Snively and Pasko, JGR, 113, A06303, 2008], allowing direct comparison of OH(6,2) intensity and brightness-weighted temperature perturbations [e.g., Makhlouf et al., JGR, 100(D6), 11289, 1995]. The strong sheared wind flow leads to dramatic variations of wave characteristics throughout the observable region, explaining the strong OH emission and relatively weak O2 emission. Krassovsky ratios and integrated cancellation effects of the modeled and observed airglow signatures are investigated, finding significant agreement, and inferred wave amplitude measurements are compared with modeled wave characteristics. Implications for wave momentum flux calculations from lidar and airglow data are discussed.

Snively, Jonathan; Pautet, Pierre-Dominique; Taylor, Michael; Swenson, Gary; Liu, Alan

2010-05-01

116

Viscosity Measurement of Highly Viscous Liquids Using Drop Coalescence in Low Gravity  

NASA Technical Reports Server (NTRS)

The method of drop coalescence is being investigated for use as a method for determining the viscosity of highly viscous undercooled liquids. Low gravity environment is necessary in this case to minimize the undesirable effects of body forces and liquid motion in levitated drops. Also, the low gravity environment will allow for investigating large liquid volumes which can lead to much higher accuracy for the viscosity calculations than possible under 1 - g conditions. The drop coalescence method is preferred over the drop oscillation technique since the latter method can only be applied for liquids with vanishingly small viscosities. The technique developed relies on both the highly accurate solution of the Navier-Stokes equations as well as on data from experiments conducted in near zero gravity environment. In the analytical aspect of the method two liquid volumes are brought into contact which will coalesce under the action of surface tension alone. The free surface geometry development as well as its velocity during coalescence which are obtained from numerical computations are compared with an analogous experimental model. The viscosity in the numerical computations is then adjusted to bring into agreement of the experimental results with the calculations. The true liquid viscosity is the one which brings the experiment closest to the calculations. Results are presented for method validation experiments performed recently on board the NASA/KC-135 aircraft. The numerical solution for this validation case was produced using the Boundary Element Method. In these tests the viscosity of a highly viscous liquid, in this case glycerine at room temperature, was determined to high degree of accuracy using the liquid coalescence method. These experiments gave very encouraging results which will be discussed together with plans for implementing the method in a shuttle flight experiment.

Antar, Basil N.; Ethridge, Edwin; Maxwell, Daniel

1999-01-01

117

Application of precise altimetry to the study of precise leveling of the sea surface, the Earth's gravity field, and the rotation of the Earth  

NASA Technical Reports Server (NTRS)

Our program includes five research items: (1) determination of a precision geoid and gravity anomaly field; (2) precise leveling and detection of tidal changes of the sea surface and study of the role of the tide in the global energy exchange; (3) oceanic effect on the Earth's rotation and polar motion; (4) geological and geophysical interpretation of the altimetry gravity field; and (5) evaluation of the effectiveness of local tracking of TOPEX/POSEIDON by use of a laser tracker.

Segawa, J.; Ganeko, Y.; Sasaki, M.; Mori, T.; Ooe, M.; Nakagawa, I.; Ishii, H.; Hagiwara, Y.

1991-01-01

118

Proof of concept and performance optimization of high gravity batch type centrifuge for dewatering fine coal  

SciTech Connect

Coal Technology Corporation (CTC) believes that the new CTC high gravity, high production, batch type centrifugal dryer technology can play a significant role in improving the product quality as well as costs of operation in coal processing plants. It is further believed that the new centrifugal dryer technology can form an important part in systems used to clean up the millions of tons of coal fines in refuse piles and ponds. It is anticipated that the new centrifuge can become an important ancillary to the advanced deep cleaning processes for coal. Because of these convictions, CTC has been engaged in a pioneering research effort into the new art of drying fine clean coal in high gravity, high production, batch type centrifuges, since 1981. This work has progressed to the point where the new centrifugal dryer technology is nearly ready for commercialization. It promises to provide needed fine coal drying capability at somewhat lower capital costs and at substantially lower operating costs than competitive systems. It also promises to do so with no detrimental effects on either the coal quality or the evironment. The primary objective of this project is to prove the concept in a commercial coal processing plant environment. The proof of concept tests will also include testing with a variety of coals from different regions. A further objective will be to optimize the efficiency and the cost effectiveness of the new centrifugal dryer technology.

Smith, L.B.; Durney, T.E. Jr.

1990-07-24

119

Influence of whole-body pitch tilt and kinesthetic cues on the perceived gravity-referenced eye level.  

PubMed

We investigated the effects of whole body tilt and lifting the arm against gravity on perceptual estimates of the Gravity-Referenced Eye Level (GREL), which corresponds to the subjective earth-referenced horizon. The results showed that the perceived GREL was influenced by body tilt, that is, lowered with forward tilt and elevated with backward tilt of the body. GREL estimates obtained by arm movements without vision were more biased by whole-body tilt than purely visual estimates. Strikingly, visual GREL estimates became more dependent on whole-body tilt when the indication of level was obtained by arm lifting. These findings indicate that active motor involvement and/or the addition of kinesthetic information increases the body tilt-induced bias when making GREL judgements. The introduction of motor/kinaesthetic cues may induce a switch from a semi-geocentric to a more egocentric frame of reference. This result challenges the assumption that combining non-conflicting multiple sensory inputs and/or using intermodal information provided during action should improve perceptual performance. PMID:14663543

Bringoux, L; Tamura, K; Faldon, M; Gresty, M A; Bronstein, A M

2004-04-01

120

Rotating disks flow under highly reduced gravity - Infinite disks with different velocities rotating at moderate Re  

NASA Astrophysics Data System (ADS)

This paper considers the solution of theoretical problems related to fluid management under conditions of highly reduced gravity. The method of Delgado et al. (1988, 1989) is extended to fluid motion induced by a pair of disks rotating at moderate Re but with strongly different velocities. Emphasis is given to exact counterrotating disks and the case of one of the disks being at rest. The solutions evolve from the corresponding creep flow and are of the Batchelor type for s = 0 and the Stewartson type for s = -1.

Delgado, A.; Rath, H. J.

121

Dynamic equilibrium under vibrations of H2 liquid-vapor interface at various gravity levels  

NASA Astrophysics Data System (ADS)

Horizontal vibration applied to the support of a simple pendulum can deviate from the equilibrium position of the pendulum to a nonvertical position. A similar phenomenon is expected when a liquid-vapor interface is subjected to strong horizontal vibration. Beyond a threshold value of vibrational velocity the interface should attain an equilibrium position at an angle to the initial horizontal position. In the present paper experimental investigation of this phenomenon is carried out in a magnetic levitation device to study the effect of the vibration parameters, gravity acceleration, and the liquid-vapor density on the interface position. The results compare well with the theoretical expression derived by Wolf [G. H. Wolf, Z. Phys. B 227, 291 (1969), 10.1007/BF01397662].

Gandikota, G.; Chatain, D.; Lyubimova, T.; Beysens, D.

2014-06-01

122

The use of high-resolution terrain data in gravity field prediction  

NASA Technical Reports Server (NTRS)

Different types of gravity prediction methods for local and regional gravity evaluation are developed, tested, and compared. Four different test areas were particularly selected in view of different prediction requirements. Also different parts of the spectrum of the gravity field were considered.

Groten, E.; Becker, M.; Euler, H.-J.; Hausch, W.; Kling, TH.

1989-01-01

123

Brane-World Gravity  

NASA Astrophysics Data System (ADS)

The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+d-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the d extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak (˜TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity “leaks” into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall-Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at low energies - the 5-dimensional Dvali-Gabadadze-Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.

Maartens, Roy; Koyama, Kazuya

2010-09-01

124

Optical emission spectroscopy of thin film fabrication by pulsed laser ablation under high-gravity  

NASA Astrophysics Data System (ADS)

We carried out the thin film deposition of iron silicide by pulsed laser ablation (PLA) on a sapphire substrate, which was placed on a high-speed rotating titanium disk. The deposited thin film exhibited a continuous composition gradient. We investigated how the continuous composition gradient was attained, because the strength of the gravity field in our experiment was far below that in the experiment on bulk crystalline compounds. In the present study, we obtain the spatial distribution of several species in the PLA plume of FeSi2 by using an intensified charge-coupled device (ICCD) camera. We obtained the distribution of each species through high-speed imaging using narrow bandpass filters, whose wavelengths corresponded to the emission wavelengths of Fe2+, Fe+, Si2+, Si+, and neutral Fe. From the observed images, we could identify the particle species as well as determine the average velocity and the relative number density of each species. The Fe2+ ions, Fe+ ions, and Fe atoms had quite different average velocities as a result of which they formed separate groups while moving toward the substrate. Species with the same valence value moves with the same velocity. We believe that the compositional gradient of FeSi2 attained under an appropriate gravity field may be explained by the movement of both the components driven by the acceleration field and the effect of selective etching.

Kajiwara, Takashi; Nishiyama, Takashi; Morinaga, Sachi; Nagayama, Kunihito

2010-12-01

125

Evaluation of an enhanced gravity-based fine-coal circuit for high-sulfur coal  

SciTech Connect

One of the main objectives of this study was to evaluate a fine-coal cleaning circuit using an enhanced gravity separator specifically for a high sulfur coal application. The evaluation not only included testing of individual unit operations used for fine-coal classification, cleaning and dewatering, but also included testing of the complete circuit simultaneously. At a scale of nearly 2 t/h, two alternative circuits were evaluated to clean a minus 0.6-mm coal stream utilizing a 150-mm-diameter classifying cyclone, a linear screen having a projected surface area of 0.5 m{sup 2}, an enhanced gravity separator having a bowl diameter of 250 mm and a screen-bowl centrifuge having a bowl diameter of 500 mm. The cleaning and dewatering components of both circuits were the same; however, one circuit used a classifying cyclone whereas the other used a linear screen as the classification device. An industrial size coal spiral was used to clean the 2- x 0.6-mm coal size fraction for each circuit to estimate the performance of a complete fine-coal circuit cleaning a minus 2-mm particle size coal stream. The 'linear screen + enhanced gravity separator + screen-bowl circuit' provided superior sulfur and ash-cleaning performance to the alternative circuit that used a classifying cyclone in place of the linear screen. Based on these test data, it was estimated that the use of the recommended circuit to treat 50 t/h of minus 2-mm size coal having feed ash and sulfur contents of 33.9% and 3.28%, respectively, may produce nearly 28.3 t/h of clean coal with product ash and sulfur contents of 9.15% and 1.61 %, respectively.

Mohanty, M.K.; Samal, A.R.; Palit, A. [South Illinois University, Carbondale, IL (United States). Dept. of Mining & Mineral Resources Engineering

2008-02-15

126

Parallel Processing at the High School Level.  

ERIC Educational Resources Information Center

This study investigated the ability of high school students to cognitively understand and implement parallel processing. Data indicates that most parallel processing is being taught at the university level. Instructional modules on C, Linux, and the parallel processing language, P4, were designed to show that high school students are highly

Sheary, Kathryn Anne

127

Gravity models of two-level collision of lithospheric plates in northeastern Asia  

NASA Astrophysics Data System (ADS)

Structural forms of emplacement of crustal and mantle rigid sheets in collision zones of lithospheric plates in northeastern Asia are analyzed using formalized gravity models reflecting the rheological properties of geological media. Splitting of the lithosphere of moving plates into crustal and mantle constituents is the main feature of collision zones, which is repeated in the structural units irrespective of their location, rank, and age. Formal signs of crustal sheet thrusting over convergent plate boundaries and subduction of the lithospheric mantle beneath these boundaries have been revealed. The deep boundaries and thickness of lithospheric plates and asthenospheric lenses have been traced. A similarity in the deep structure of collision zones of second-order marginal-sea buffer plates differing in age is displayed at the boundaries with the Eurasian, North American, and Pacific plates of the first order. Collision of oceanic crustal segments with the Mesozoic continental margin in the Sikhote-Alin is characterized, as well as collision of the oceanic lithosphere with the Kamchatka composite island arc. A spatiotemporal series of deep-seated Middle Mesozoic, Late Mesosoic, and Cenozoic collision tectonic units having similar structure is displayed in the transitional zone from the Asian continent to the Pacific plate.

Petrishchevsky, A. M.

2013-11-01

128

Gravity, Time, and Lagrangians  

ERIC Educational Resources Information Center

Feynman mentioned to us that he understood a topic in physics if he could explain it to a college freshman, a high school student, or a dinner guest. Here we will discuss two topics that took us a while to get to that level. One is the relationship between gravity and time. The other is the minus sign that appears in the Lagrangian. (Why would one…

Huggins, Elisha

2010-01-01

129

High Level Machine-Tool Control System,  

National Technical Information Service (NTIS)

The manual describes the High Level Machine-tool Controller (HLMC) in the Horizontal Workstation (HWS) of the Automated Manufacturing Research Facility (AMRF). Though the current implementation of the HLMC was designed for the HWS, there is sufficient mod...

D. Fishman

1988-01-01

130

High-level test compaction techniques  

Microsoft Academic Search

Available register-transfer level (RTL) test generation techniques do not make a concerted effort to reduce the test application time associated with the derived tests. Chip tester memory limitations, increasing tester costs, etc., make it imperative that the issue of generating compact tests at the RTL be addressed and consolidated with the known gains of high-level testing. In this paper, the

Srivaths Ravi; Ganesh Lakshminarayana; Niraj K. Jha

2002-01-01

131

Conceptual Framework for High-level Vision  

Microsoft Academic Search

In this report we present essential elements of a conceptual framework for high-level vision (HLV). The scope of HLV is defined as scene interpretation above the level of object recognition. It is shown that models, on which such interpretations can be based, typically describe aggregates composed of meaningful parts, related to each other by temporal and spatial constraints. A frame-based

Bernd Neumann

2002-01-01

132

Exploring Quantum Gravity with Very-High-Energy Gamma-Ray Instruments - Prospects and Limitations  

SciTech Connect

Some models for quantum gravity (QG) violate Lorentz invariance and predict an energy dependence of the speed of light, leading to a dispersion of high-energy gamma-ray signals that travel over cosmological distances. Limits on the dispersion from short-duration substructures observed in gamma-rays emitted by gamma-ray bursts (GRBs) at cosmological distances have provided interesting bounds on Lorentz invariance violation (LIV). Recent observations of unprecedentedly fast flares in the very-high energy gamma-ray emission of the active galactic nuclei (AGNs) Mkn 501 in 2005 and PKS 2155-304 in 2006 resulted in the most constraining limits on LIV from light-travel observations, approaching the Planck mass scale, at which QG effects are assumed to become important. I review the current status of LIV searches using GRBs and AGN flare events, and discuss limitations of light-travel time analyses and prospects for future instruments in the gamma-ray domain.

Wagner, Robert [Max-Planck-Institut fuer Physik, D-80805 Muenchen (Germany)

2009-04-08

133

Improvement of the fatigue strength of aluminium alloy welded joints by high hardness and large specific gravity shot peening  

Microsoft Academic Search

The shot peening method, which requires simple equipment and treatment, is extensively employed as a method to improve fatigue strength. However, conventional steel ball shot material has a low specific gravity, so high speed projection is required in order to improve fatigue strength; thus, the accompanying noise and high air flow are problems. Accordingly, in order to improve these aspects,

M. Hasegawa; H. Suzuki

2005-01-01

134

Melt-Casting of Translucent MgAl2O4 Ceramics by Combustion Synthesis Under High Gravity  

Microsoft Academic Search

Translucent MgAl2O4 was prepared by combustion synthesis melt-casting under high gravity. Compared with common gravitational condition, under high-gravity condition the separation between ceramic and metal melts was accelerated, and thus the content of residual Ni in MgAl2O4 ingot was reduced. By the incorporation of SiO2 or Si-Na-Ca-Mg-O glass additives, residual Ni was eliminated and single-phase MgAl2O4 was obtained. On the

Guanghua Liu; Jiangtao Li; Zengchao Yang

2012-01-01

135

Melt-Casting of Translucent MgAl2O4 Ceramics by Combustion Synthesis Under High Gravity  

Microsoft Academic Search

Translucent MgAl2O4 was prepared by combustion synthesis melt-casting under high gravity. Compared with common gravitational condition, under high-gravity condition the separation between ceramic and metal melts was accelerated, and thus the content of residual Ni in MgAl2O4 ingot was reduced. By the incorporation of SiO2 or Si-Na-Ca-Mg-O glass additives, residual Ni was eliminated and single-phase MgAl2O4 was obtained. On the

Guanghua Liu; Jiangtao Li; Zengchao Yang

2011-01-01

136

Complete Bouguer gravity map of the Nevada Test Site and vicinity, Nevada  

SciTech Connect

About 15,000 gravity stations were used to create the gravity map. Gravity studies at the Nevada Test Site were undertaken to help locate geologically favorable areas for underground nuclear tests and to help characterize potential high-level nuclear waste storage sites. 48 refs. (TEM)

Healey, D.L.; Harris, R.N.; Ponce, D.A.; Oliver, H.W.

1987-12-31

137

Orbital Gravity Gradiometry Beyond GOCE: Geophysical Applications  

NASA Astrophysics Data System (ADS)

We examine scientific applications of time-variable high-resolution global gravity field solutions anticipated from the multi-year gravity mission with the advanced superconducting gravity gradiometer (SGG). By virtue of the improved technology including cryogenics, the anticipated noise level of the SGG is 0.01 mE/?Hz at the measurement bandwidth of 0.5 mHz to 0.1 Hz (300 times more precise over a wider frequency band than the GOCE gradiometer). It will allow not only the observations of various geophysical mass redistributions manifested in time-variable gravity fields at higher spatial resolution than GRACE, but also another leap in the accuracy and resolution of the (static) mean gravity field beyond GOCE. Gradiometry measurements have a full 3D observability and are not limited to, for example, along-track observations in the case of low-low satellite-to-satellite tracking system. However, gravity gradient measurements are less sensitive to long wavelength components of the gravity field. Based on forward modeling and inversion of simulated measurements, the spatial and temporal resolutions of the global and regional mass variations achievable from the proposed SGG mission will be delineated and compared with the results from GRACE and anticipated results from the GRACE follow-on laser interferometry mission. With the improved gravity sensor technology (satellite-to-satellite tracking or gradiometer), the quality of the gravity fields from future missions is likely to be limited by the fidelities of the so-called background (forward) models, including atmospheric loading and ocean tide perturbations. Errors in these background models introduce high frequency (temporal and spatial) mass variations that alias into the gravity solutions. We will quantify the aliasing effect of high frequency signals on the monthly (or so) mean gravity field solutions.

Paik, H.; Moody, M. V.; Venkateswara, K. Y.; Han, S.; Ditmar, P.; Klees, R.; Shirron, P. J.; Dipirro, M. J.; Canavan, E. R.; Jekeli, C.; Shum, C.

2010-12-01

138

Propagation and Breaking at High Altitudes of Gravity Waves Excited by Tropospheric Forcing  

NASA Technical Reports Server (NTRS)

An anelastic approximation is used with a time-variable coordinate transformation to formulate a two-dimensional numerical model that describes the evolution of gravity waves. The model is solved using a semi-Lagrangian method with monotone (nonoscillatory) interpolation of all advected fields. The time-variable transformation is used to generate disturbances at the lower boundary that approximate the effect of a traveling line of thunderstorms (a squall line) or of flow over a broad topographic obstacle. The vertical propagation and breaking of the gravity wave field (under conditions typical of summer solstice) is illustrated for each of these cases. It is shown that the wave field at high altitudes is dominated by a single horizontal wavelength; which is not always related simply to the horizontal dimension of the source. The morphology of wave breaking depends on the horizontal wavelength; for sufficiently short waves, breaking involves roughly one half of the wavelength. In common with other studies, it is found that the breaking waves undergo "self-acceleration," such that the zonal-mean intrinsic frequency remains approximately constant in spite of large changes in the background wind. It is also shown that many of the features obtained in the calculations can be understood in terms of linear wave theory. In particular, linear theory provides insights into the wavelength of the waves that break at high altitudes, the onset and evolution of breaking. the horizontal extent of the breaking region and its position relative to the forcing, and the minimum and maximum altitudes where breaking occurs. Wave breaking ceases at the altitude where the background dissipation rate (which in our model is a proxy for molecular diffusion) becomes greater than the rate of dissipation due to wave breaking, This altitude, in effect, the model turbopause, is shown to depend on a relatively small number of parameters that characterize the waves and the background state.

Prusa, Joseph M.; Smolarkiewicz, Piotr K.; Garcia, Rolando R.

1996-01-01

139

High level performance estimate of relational queries  

SciTech Connect

Performance estimate of queries is a necessary part of any efficient database design methodology. A high-level performance estimator for relational queries is presented which is different from conventional evaluators such as SYSTEM R (Selinger, Proc. SIGMOD 79) in that performance is predicted without the details of the low-level constructs such as links and indices. Rather, abstractions and reasonable assumptions of these low-level constructs are used in a set of formulas to estimate the performance of a set of queries against a schema. The major results of the paper are the realization and motivation of the need of high-level performance estimators of this kind, and a fast way to estimate the cost of N-way joins. The second result is interesting in that the algorithm for N-way joins is found to be similar to matrix multiplication optimization, with straightforward extensions.

Wong, H.K.T.

1980-08-01

140

Acceleration levels on board the Space Station and a tethered elevator for micro and variable-gravity applications  

NASA Technical Reports Server (NTRS)

This paper investigates the dynamics and acceleration levels of a new tethered system for micro and variable-gravity applications. The system consists of two platforms tethered on opposite sides to the Space Station. A fourth platform, the elevator, is placed in between the Space Station and the upper platform. Variable-g levels on board the elevator are obtained by moving this facility along the upper tether, while micro-g experiments are carried out on board the Space Station. By controlling the length of the lower tether the position of the system CM can be maintained on board the Space Station despite variations of the station's distribution of mass. The paper illustrates the mathematical model, the environmental perturbations and the control techniques which have been adopted for the simulation and control of the system dynamics. Two sets of results from two different simulation runs are shown. The first set shows the system dynamics and the acceleration spectra on board the Space Station and the elevator during station-keeping. The second set of results demonstrates the capability of the elevator to attain a preselected g-level.

Lorenzini, E. C.; Cosmo, M.; Vetrella, S.; Moccia, A.

1988-01-01

141

Measuring the Value of High Level Fusion  

Microsoft Academic Search

In most current ground force combat simulations, the operational movements and command intent of forces follow prescribed, inflexible objectives and plans. Because of this limitation, the value of advanced intelligence, surveillance, and reconnaissance (ISR) and high-level fusion is reflected only in better targeting and not in improved operational-level command and control (C2). RAND has developed an agent interaction-based constructive simulation

Louis R. Moore; Daniel Gonzales

142

High-level waste processing and disposal  

NASA Astrophysics Data System (ADS)

The national high level waste disposal plans for France, the Federal Republic of Germany, Japan, and the United States are covered. Three conclusions are reached. The first conclusion is that an excellent technology already exists for high level waste disposal. With appropriate packaging, spent fuel seems to be an acceptable waste form. Borosilicate glass reprocessing waste forms are well understood, in production in France, and scheduled for production in the next few years in a number of other countries. For final disposal, a number of candidate geological repository sites have been identified and several demonstration sites opened. The second conclusion is that adequate financing and a legal basis for waste disposal are in place in most countries. Costs of high level waste disposal will probably and about 5 to 10% to the costs of nuclear electric power. Third conclusion is less optimistic.

Crandall, J. L.; Drause, H.; Sombret, C.; Uematsu, K.

143

A Software Architecture for High Level Applications  

SciTech Connect

A modular software platform for high level applications is under development at the National Synchrotron Light Source II project. This platform is based on client-server architecture, and the components of high level applications on this platform will be modular and distributed, and therefore reusable. An online model server is indispensable for model based control. Different accelerator facilities have different requirements for the online simulation. To supply various accelerator simulators, a set of narrow and general application programming interfaces is developed based on Tracy-3 and Elegant. This paper describes the system architecture for the modular high level applications, the design of narrow and general application programming interface for an online model server, and the prototype of online model server.

Shen,G.

2009-05-04

144

High-Level Data-Abstraction System  

NASA Technical Reports Server (NTRS)

Communication with data-base processor flexible and efficient. High Level Data Abstraction (HILDA) system is three-layer system supporting data-abstraction features of Intel data-base processor (DBP). Purpose of HILDA establishment of flexible method of efficiently communicating with DBP. Power of HILDA lies in its extensibility with regard to syntax and semantic changes. HILDA's high-level query language readily modified. Offers powerful potential to computer sites where DBP attached to DEC VAX-series computer. HILDA system written in Pascal and FORTRAN 77 for interactive execution.

Fishwick, P. A.

1986-01-01

145

High Resolution Airborne Gravity Gradiometer Based on an Othogonal Mass Quadruploe  

NASA Astrophysics Data System (ADS)

The Gedex Airborne Gravity Gradiometer (AGG) uses an orthogonal quadrupole responder (OQR) developed at the University of Western Australia with support from Rio Tinto. The OQR design is based on pairs of balance beams orientated at 90 degrees to one another, with each beam supported on a micro-flexure. A gradient along the length of a beam in the gravitational acceleration component that is perpendicular to the beam axis and the web axis will generate a small torque about the flexure. With two orthogonal beams, rotations of the base will result in both beams rotating in a common direction compared to the base, whereas the beams will rotate in opposite, or differential, directions due to gravity gradients. The differential rotation arises because of the properties of the gravity gradient tensor. The sensor can thus in principle distinguish between base rotations and gravity gradients. Additionally the beams are designed such that the center of rotation about the supporting flexures coincides with the location of the center of mass of the beams. This eliminates rotational response of the beams when subjected to linear accelerations. Thus the OQR configuration provides a sensor that is inherently insensitive to both rotational and linear accelerations of the support. However, the practical world has a habit of complicating seemingly simple situations. The first design challenge is that fabrication of the beams and the supporting flexures has to be done to very stringent tolerances, which has only recently become possible with the development of technologies such as Electric Discharge Machining (EDM). The second major obstacle is that there are higher order terms in the response of the sensing elements that can be driven by base vibrations and aircraft motions. These require mounting the sensor on an isolation system designed to provide a very low level of disturbance to the gradiometer. In the Gedex development this isolation system is based on technology developed by the Canadian Space Agency (CSA) over the past decade. The CSA has flown isolation systems on the Russian Mir space station and on the US space shuttle, and is currently developing two versions for the International Space Station (ISS). Gedex is adapting this technology for airborne use. When the full set of error terms are examined it becomes clear that they can be classified into three main groups, one of which is sensor independent, one of which is sensor specific, and one group that depend on a combination of parameters, some sensor independent and some sensor specific. In the case of the Gedex gradiometer mounted on the isolation system in an aircraft, these error terms combine to give a resolution of one Eotvos at one sample per second, corresponding to a spatial sampling resolution of 50m for a platform translating at 100 knots (˜50m/s). This paper will provide an overview of the total AGG system design, and a summary of the predicted performance.

Tryggvason, B. V.

2003-04-01

146

ESTIMATION OF HELMERT ORTHOMETRIC HEIGHTS USING DIGITAL BARCODE LEVELLING, OBSERVED GRAVITY AND TOPOGRAPHIC MASS-DENSITY DATA OVER PART OF THE DARLING SCARP, WESTERN AUSTRALIA  

Microsoft Academic Search

The normal orthometric corrections used in the 1971 establishment of the Australian Height Datum (AHD) do not properly account for local variations in the Earth's gravity field. Therefore, Helmert orthometric heights have been computed over a spirit-levelled height traverse over part of the Darling Fault and compared with normal orthometric heights. This involves a measured height change of ~175m, a

N. A. Allister; W. E. Featherstone

147

High degree gravitational sensitivity from Mars orbiters for the GMM-1 gravity model  

NASA Technical Reports Server (NTRS)

Orbital sensitivity of the gravity field for high degree terms (greater than 30) is analyzed on satellites employed in a Goddard Mars Model GMM-1, complete in spherical harmonics through degree and order 50. The model is obtained from S-band Doppler data on Mariner 9 (M9), Viking Orbiter 1 (VO1), and Viking Orbiter 2 (VO2) spacecraft, which were tracked by the NASA Deep Space Network on seven different highly eccentric orbits. The main sensitivity of the high degree terms is obtained from the VO1 and VO2 low orbits (300 km periapsis altitude), where significant spectral sensitivity is seen for all degrees out through degree 50. The velocity perturbations show a dominant effect at periapsis and significant effects out beyond the semi-latus rectum covering over 180 degrees of the orbital groundtrack for the low altitude orbits. Because of the wideband of periapsis motion covering nearly 180 degrees in w and +39 degrees in latitude coverage, the VO1 300 km periapsis altitude orbit with inclination of 39 degrees gave the dominant sensitivity in the GMM-1 solution for the high degree terms. Although the VO2 low periapsis orbit has a smaller band of periapsis mapping coverage, it strongly complements the VO1 orbit sensitivity for the GMM-1 solution with Doppler tracking coverage over a different inclination of 80 degrees.

Lerch, F. J.; Smith, D. E.; Chan, J. C.; Patel, G. B.; Chinn, D. S.

1994-01-01

148

Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs  

Microsoft Academic Search

Free-air gravity highs over forearcs represent a large fraction of the power in the Earth`s anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local

Geoffrey A. Abers

1994-01-01

149

Validation of GOCE gravity field models using GPS-leveling data and EGM08: a case study in Brazil  

NASA Astrophysics Data System (ADS)

Validation of geopotential models derived from Gravity field and steady-state Ocean Circulation Explorer (GOCE) observations is a challenging task in regions with less advanced geodetic infrastructure such as Brazil. In order to assess the current performance of these models, 262 GPS-leveling sites, Earth Gravitational Model 2008 (EGM08) and Residual Terrain Model (RTM) are employed. The validation is based on the differences between GPS-leveling and GOCE-derived models. For the former, the spectral content beyond the GOCE-derived models' maximum degree is removed by using EGM08 and RTM. The results indicate that the GOCE-based models: DGM-1S, SPW (Releases 1 and 2), TIM (Releases 1, 2, 3 and 4), and DIR (Releases 2, 3 and 4), at their maximum degrees have a worse performance than EGM08 while DIR-R1 shows an improvement of 11%. Furthermore, from the steepness of the slopes of the root mean square error (RMSE), it is observed that the optimal combination between DIR-R1 and EGM08 occurs at degree 230 (RMSE of 0.201 m). For the satellite-only models, DIR-R3 reduces the RMSE by ~1.4% compared to TIM-R4 at degree 190. These results are important for Brazil where the accuracy of the current geoid model is approximately 0.28 m.

Ferreira, V. G.; Zhang, Y.; de Freitas, S. R. C.

2013-09-01

150

Network-Based High Level Data Classification  

Microsoft Academic Search

Traditional supervised data classification considers only physical features (e.g., distance or similarity) of the input data. Here, this type of learning is called low level classification. On the other hand, the human (animal) brain performs both low and high orders of learning and it has facility in identifying patterns according to the semantic meaning of the input data. Data classification

Thiago Christiano Silva; Liang Zhao

2012-01-01

151

High Noise Level Microphones Used in Aircraft.  

National Technical Information Service (NTIS)

The objective of this paper is to do a comparative analysis of three of the present state of the art high noise level microphones. They are the M-87/AIC and M-87/AIC+ (EV 693) both made by Electro-Voice and the HNL bone conduction microphone made by SETCO...

E. J. Hintz

1974-01-01

152

Vitrification of High-Level Liquid Wastes.  

National Technical Information Service (NTIS)

High-level radioactive liquid wastes produced in the fuel elements reprocessing require, for their disposal, a preliminary treatment by which, through a series of engineering barriers, the dispersion into the biosphere is delayed by 10,000 years. Four gro...

J. L. Varani E. J. Petraitis A. Vazquez

1987-01-01

153

High-Level Waste Melter Review  

Microsoft Academic Search

The U.S. Department of Energy (DOE) is faced with a massive cleanup task in resolving the legacy of environmental problems from years of manufacturing nuclear weapons. One of the major activities within this task is the treatment and disposal of the extremely large amount of high-level radioactive (HLW) waste stored at the Hanford Site in Richland, Washington. The current planning

J. Ahearne; J. Gentilucci; L. D. Pye; T. Weber; F. Woolley; N. P. Machara; K. Gerdes; C. Cooley

2002-01-01

154

Applying simulated evolution to high level synthesis  

Microsoft Academic Search

A general optimization algorithm known as simulated evolution (SE) is applied to the tasks of scheduling and allocation in high level synthesis. Basically, SE-based synthesis explores the design space by repeatedly ripping up parts of a design in a probabilistic manner and reconstructing them using application-specific heuristics that combine rapid design iterations and probabilistic hill climbing to achieve effective design

Tai A. Ly; Jack T. Mowchenko

1993-01-01

155

High-Level Architecture (HLA) Transition Report.  

National Technical Information Service (NTIS)

This report is a product of the High Level Architecture (HLA) transition Issues Team, a caucus of representatives from the DoD Component (modeling and simulation) M&S Management Offices and the Defense Modeling and Simulation Office (DMSO). This team oper...

1998-01-01

156

High-Level Architecture (HLA) Transition Report.  

National Technical Information Service (NTIS)

This report is the second published product of the High Level Architecture (HLA) Transition Issues Team, an approved subgroup of the DoD executive Council for Modeling and Simulation (EXCIMS) composed of representatives from the DoD Component Modeling and...

1999-01-01

157

Time Management in The High Level Architecture  

Microsoft Academic Search

Time management is required in simulations to ensure temporal aspects of the system under investigation are correctly reproduced by the simulation model. This paper describes the time management services that have been defined in the High Level Architecture. The need for time management services is discussed, as well as design rationales that lead to the current definition of the HLA

Richard M. Fujimoto

1998-01-01

158

HIGH LEVEL LIQUID WASTE SOLIDIFICATION USING A \\  

Microsoft Academic Search

At the present time the primary problem in a closed nuclear fuel cycle is the management of high level liquid waste (HLLW) generated by the recovery of uranium and plutonium from the spent nuclear fuel. Long-term storage of the HLLW, even in special storage facilities, poses a real threat of ecological accidents. This problem can be solved by incorporating the

Tatyana V. Smelova; Nina V. Krylova; Igor N. Shestoperov; Andrei V. Demine

2000-01-01

159

Optical Mass Gauging System for Measuring Liquid Levels in a Reduced Gravity Environment  

NASA Technical Reports Server (NTRS)

A compact and rugged fiber-coupled liquid volume sensor designed for flight on a sounding rocket platform is presented. The sensor consists of a Mach-Zehnder interferometer capable of measuring the amount of liquid contained in a tank under any gravitational conditions, including a microgravity environment, by detecting small changes in the index of refraction of the gas contained within a sensing region. By monitoring changes in the interference fringe pattern as the system undergoes a small compression provided by a piston, the ullage volume of a tank can be directly measured allowing for a determination of the liquid volume. To demonstrate the technique, data are acquired using two tanks containing different volumes of liquid, which are representative of the levels of liquid in a tank at different time periods during a mission. The two tanks are independently exposed to the measurement apparatus, allowing for a determination of the liquid level in each. In a controlled, laboratory test of the unit, the system demonstrated a capability of measuring a liquid level in an individual tank of 10.53 mL with a 2% error. The overall random uncertainty for the flight system is higher than that one test, at +/- 1.5 mL.

Sullenberger, Ryan M.; Munoz, Wesley M.; Lyon, Matt P.; Vogel, Kenny; Yalin, Azer P.; Korman, Valentin; Polzin, Kurt A.

2010-01-01

160

The energetics and mechanics of level and gradient skipping: Preliminary results for a potential gait of choice in low gravity environments.  

NASA Astrophysics Data System (ADS)

Walking and running in low gravity cannot be used at useful speeds, while 'skipping', a gait displayed by kids and spontaneously adopted by astronauts of Apollo missions, proved to have the potential to become the gait of choice in that condition. In this paper the previous biomechanical and metabolic analysis of level skipping is extended to positive and negative gradients, in normal gravity. The results confirm at all gradients the higher (average) ground reaction force during the contact phase, with respect to running at the same speed, which would allow confidently facing the Lunar surface where the dust and regoliths affect, in addition to a lower gravity, the locomotion dynamics. Metabolic data, other gait variables related to the mechanical work done and the locomotor/respiratory coupling have also been investigated.

Minetti, Alberto E.; Pavei, Gaspare; Biancardi, Carlo M.

2012-12-01

161

Crustal Structure of the High Lava Plains of the Pacific Northwest - Source Seismic and Gravity Modeling  

NASA Astrophysics Data System (ADS)

This study uses data from the High Lava Plains (HLP) experiment collected in September 2008. A total of 2612 Texan short-period seismic recorders and 120 RT-130 recorders were spaced across the HLP of eastern Oregon and adjacent parts of Nevada and Idaho to record 15 seismic sources thanks to the help of the 67 scientists, students, and 6 staff members from the PASSCAL/Earthscope Instrument Center who deployed. The purpose of this study is to integrate the seismic and gravity data to create 2D crustal scale P-wave seismic velocity and density models across the NW-SE and N-S transecting profiles. These models provide a better understanding of the crustal structure and upper mantle beneath the path of volcanism that dotted the High Lava Plains during the past 16 Ma, in addition to the extension experienced in the region since 35 Ma. Our results show that the crustal structure across the HLP region is similar to that of the northern Basin and Range. However, a thick cover (5-7 km) of sediments and volcanics covers most of the area in addition to the Harney Basin. Based on the gravity data, denser material underlies the southern part of the Harney Basin which might be mafic material based on its close proximity to Diamond Craters. This might also support the assertion that there is a caldera system underlying the HLP. The crust thickens (34km -37km) and increases in density (2.8-2.85 gm/cc) from west to eat across eastern Oregon in close proximity to the interpreted position of the 0.706 Sr isotope line. There is thin layer of relatively high velocities (7.2-7.4 km/s) and densities of (2.95 gm/cc) in the lowermost crust suggest underplating. Also, the average crustal velocity is somewhat higher that in the adjacent Basin and Range suggesting some magmatic modification in the lower crust but not as much as might be expected given the voluminous surface volcanism.

Cox, C.; Keller, G. R.

2010-12-01

162

An estimation of the height system bias parameter N 0 using least squares collocation from observed gravity and GPS-levelling data  

Microsoft Academic Search

This paper deals with the analysis of gravity anomaly and precise levelling in conjunction with GPS-Levelling data for the\\u000a computation of a gravimetric geoid and an estimate of the height system bias parameter No for the vertical datum in Pakistan by means of least squares collocation technique. The long term objective is to obtain\\u000a a regional geoid (or quasi-geoid) modeling

Muhammad Sadiq; Carl C. Tscherning; Zulfiqar Ahmad

2009-01-01

163

High-Level Integration of Data Systems  

NASA Astrophysics Data System (ADS)

One of the key capabilities required for data systems of the future is the integration of high-level systems and services into their design. Future systems need to provide users with integrated access to distributed and diverse scientific data holdings, models, services, and tools in order to increase the science and educational return from the data. These new capabilities go well beyond the garden variety "get me data" types of services and should be accomplished as part of a broader structure which ties together existing systems at the same time as introducing new capabilities. Here, we present the high-level integration of systems and services as the necessary pieces to accomplish this as well as some lessons learned. and http://sd-www.jhuapl.edu/SPDML/index.php

Weiss, M.; Morrison, D.; Daley, R.; Immer, E.; Hashemian, M.; Fortner, B.; Jen, J.; Holder, R.

2005-12-01

164

High-Level Waste Melter Review  

SciTech Connect

The U.S. Department of Energy (DOE) is faced with a massive cleanup task in resolving the legacy of environmental problems from years of manufacturing nuclear weapons. One of the major activities within this task is the treatment and disposal of the extremely large amount of high-level radioactive (HLW) waste stored at the Hanford Site in Richland, Washington. The current planning for the method of choice for accomplishing this task is to vitrify (glassify) this waste for disposal in a geologic repository. This paper describes the results of the DOE-chartered independent review of alternatives for solidification of Hanford HLW that could achieve major cost reductions with reasonable long-term risks, including recommendations on a path forward for advanced melter and waste form material research and development. The potential for improved cost performance was considered to depend largely on increased waste loading (fewer high-level waste canisters for disposal), higher throughput, or decreased vitrification facility size.

Ahearne, J.; Gentilucci, J.; Pye, L. D.; Weber, T.; Woolley, F.; Machara, N. P.; Gerdes, K.; Cooley, C.

2002-02-26

165

Influence of pitch tilts on the perception of gravity-referenced eye level in labyrinthine defective subjects.  

PubMed

We investigate the role of vestibular information in judging the gravity-referenced eye level (i.e., earth-referenced horizon or GREL) during sagittal body tilt whilst seated. Ten bilateral labyrinthine-defective subjects (LDS) and 10 age-matched controls set a luminous dot to their perception of GREL in darkness, with and without arm pointing. Although judgements were linearly influenced by the magnitude of whole-body tilt, results showed no significant difference between LDS and age-matched controls in the subjective GREL accuracy or in the intra-subject variability of judgement. However, LDS performance without arm pointing was related to the degree of vestibular compensation inferred from another postural study performed with the same patients. LDS did not utilize upper limb input during arm pointing movements as a source of graviceptive information to compensate for the vestibular loss. The data suggest that vestibular cues are not of prime importance in GREL estimates in static conditions. The absence of difference between controls and LDS GREL performance, and the correlation between the postural task and GREL accuracy, indicate that somatosensory input may convey as much graviceptive information required for GREL judgements as the vestibular system. PMID:17101157

Bringoux, L; Mezey, L E; Faldon, M; Gresty, M A; Bronstein, A M

2007-01-28

166

Commissioning of the CMS High Level Trigger  

SciTech Connect

The CMS experiment will collect data from the proton-proton collisions delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to 14 TeV. The CMS trigger system is designed to cope with unprecedented luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger architecture only employs two trigger levels. The Level-1 trigger is implemented using custom electronics, while the High Level Trigger (HLT) is based on software algorithms running on a large cluster of commercial processors, the Event Filter Farm. We present the major functionalities of the CMS High Level Trigger system as of the starting of LHC beams operations in September 2008. The validation of the HLT system in the online environment with Monte Carlo simulated data and its commissioning during cosmic rays data taking campaigns are discussed in detail. We conclude with the description of the HLT operations with the first circulating LHC beams before the incident occurred the 19th September 2008.

Agostino, Lorenzo; et al.

2009-08-01

167

Effects of topographic and isostatic masses in satellite gravity gradiometry  

Microsoft Academic Search

Gravity gradiometry is strongly sensitive to the gravity field induced by the topographic and isostatic masses of the Earth. The downward continuation of the gravitational signals from satellite height to sea level is rather difficult because of the high-frequency behaviour of the combined topographic and isostatic effect. Therefore it is reasonable to smooth the gravitational signals by some topographic-isostatic reduction

F. Wild; B. Heck

2004-01-01

168

High level intelligent control of telerobotics systems  

NASA Technical Reports Server (NTRS)

A high level robot command language is proposed for the autonomous mode of an advanced telerobotics system and a predictive display mechanism for the teleoperational model. It is believed that any such system will involve some mixture of these two modes, since, although artificial intelligence can facilitate significant autonomy, a system that can resort to teleoperation will always have the advantage. The high level command language will allow humans to give the robot instructions in a very natural manner. The robot will then analyze these instructions to infer meaning so that is can translate the task into lower level executable primitives. If, however, the robot is unable to perform the task autonomously, it will switch to the teleoperational mode. The time delay between control movement and actual robot movement has always been a problem in teleoperations. The remote operator may not actually see (via a monitor) the results of high actions for several seconds. A computer generated predictive display system is proposed whereby the operator can see a real-time model of the robot's environment and the delayed video picture on the monitor at the same time.

Mckee, James

1988-01-01

169

High resolution (10 km, 3mGal) gravity mapping of the Global continental margins using ERS1 and Geosat satellite altimeter data  

NASA Astrophysics Data System (ADS)

Converting sea-surface height variations, derived from satellite altimetry, to free air gravity is not new. What is new is our ability to use existing satellite data to resolve anomalies down to 10 km wavelength and to within 2 to 5 km of the coast globally. Since 1993, GETECH, University of Leeds, has been involved in developing new methods and techniques to recover gravity from satellite altimeter data with the specific aim of improving oil exploration methods in deep-water areas of the continental margins, worldwide. By a combination of new processing methods, we can recover anomalies that are accurately and reliably representing geological structures down to 10 km in wavelength. These improvements have been possible by applying: -advanced seismic repicking methods to recover the onset of ERS-1 radar waveforms; -a range of more accurate and globally consistent wet and dry Troposphere propagation and tidal corrections; -careful data editing and validation based on data visualisation techniques; -micro-levelling to resolve discrepancies between satellite tracks in order to derive a reliable geoid surface; and -the `Geoid to Gravity' conversion method which has significant advantages over existing methods The methodology has allowed us to map to within 2 and 5 km of the coast, globally, and significantly suppress noise that is prevalent and dominates existing solutions at 40 km and shorter wavelengths. At these and shorter wavelengths the geological signal is effectively masked by the noise. The global continental margins study was completed in June 2004 and examples of the resolution improvements for the Gulf of Mexico and S E Asia are shown. Key words: Satellite gravity, high-resolution, continental margins.

Fairhead, J. D.; Green, C. M.; Fletcher, K. M.

2004-12-01

170

Quasi-Stagnation Levels in the Ion Motion Induced by Internal Atmospheric Gravity Waves at Ionospheric Heights.  

National Technical Information Service (NTIS)

The report theoretically demonstrates the existence, under appropriate ionospheric conditions, of a height or heights at which the vertical ion motion induced by a single internal atmospheric gravity wave vanishes identically, at all phases of the wave cy...

W. H. Hooke

1970-01-01

171

Feeling Gravity's Pull: Gravity Modeling. The Gravity Field of Mars  

NASA Technical Reports Server (NTRS)

Most people take the constant presence of gravitys pull for granted. However, the Earth's gravitational strength actually varies from location to location. This variation occurs because mass, which influences an object's gravitational pull, is not evenly distributed within the planet. Changes in topography, such as glacial movement, an earthquake, or a rise in the ocean level, can subtly affect the gravity field. An accurate measurement of the Earth's gravity field helps us understand the distribution of mass beneath the surface. This insight can assist us in locating petroleum, mineral deposits, ground water, and other valuable substances. Gravity mapping can also help notice or verify changes in sea surface height and other ocean characteristics. Such changes may indicate climate change from polar ice melting and other phenomena. In addition, gravity mapping can indicate how land moves under the surface after earthquakes and other plate tectonic processes. Finally, changes in the Earth's gravity field might indicate a shift in water distribution that could affect agriculture, water supplies for population centers, and long-term weather prediction. Scientists can map out the Earth's gravity field by watching satellite orbits. When a satellite shifts in vertical position, it might be passing over an area where gravity changes in strength. Gravity is only one factor that may shape a satellite's orbital path. To derive a gravity measurement from satellite movement, scientists must remove other factors that might affect a satellite's position: 1. Drag from atmospheric friction. 2. Pressure from solar radiation as it heads toward Earth and. as it is reflected off the surface of the Earth 3. Gravitational pull from the Sun, the Moon, and other planets in the Solar System. 4. The effect of tides. 5. Relativistic effects. Scientists must also correct for the satellite tracking process. For example, the tracking signal must be corrected for refraction through the atmosphere of the Earth. Supercomputers can calculate the effect of gravity for specific locations in space following a mathematical process known as spherical harmonics, which quantifies the gravity field of a planetary body. The process is based on Laplace's fundamental differential equation of gravity. The accuracy of a spherical harmonic solution is rated by its degree and order. Minute variations in gravity are measured against the geoid, a surface of constant gravity acceleration at mean sea level. The geoid reference gravity model strength includes the central body gravitational attraction (9.8 m/sq s) and a geopotential variation in latitude partially caused by the rotation of the Earth. The rotational effect modifies the shape of the geoid to be more like an ellipsoid, rather than a perfect, circle. Variations of gravity strength from the ellipsoidal reference model are measured in units called milli-Galileos (mGals). One mGal equals 10(exp -5) m/sq s. Research projects have also measured the gravity fields of other planetary bodies, as noted in the user profile that follows. From this information, we may make inferences about our own planet's internal structure and evolution. Moreover, mapping the gravity fields of other planets can help scientists plot the most fuel-efficient course for spacecraft expeditions to those planets.

Lemoine, Frank; Smith, David; Rowlands, David; Zuber, Maria; Neumann, G.; Chinn, Douglas; Pavlis, D.

2000-01-01

172

High Energy Astrophysics Tests of Lorentz Invariance and Quantum Gravity Models  

NASA Technical Reports Server (NTRS)

High energy astrophysics observations provide the best possibilities to detect a very small violation of Lorentz invariance such as may be related to the structure of space-time near the Planck scale of approx.10(exp -35) m. I will discuss the possible signatures of Lorentz invariance violation (LIV) that can be manifested by observing of the spectra, polarization, and timing of gamma-rays from active galactic nuclei and gamma-ray bursts. Other sensitive tests are provided by observations of the spectra of ultrahigh energy cosmic rays and neutrinos. Using the latest data from the Pierre Auger Observatory one can already derive an upper limit of 4.5 x 10(exp -23) on the fraction of LIV at a Lorentz factor of approx. 2 x 10(exp 11). This result has fundamental implications for quantum gravity models. I will also discuss the possibilities of using more sensitive space-based detection techniques to improve searches for LIV in the future. I will also discuss how the LIV formalism casts doubt on the OPERA superluminal neutrino claim.

Stecker, Floyd W.

2012-01-01

173

Accelerated carbonation of steelmaking slags in a high-gravity rotating packed bed.  

PubMed

Carbon dioxide (CO(2)) sequestration using the accelerated carbonation of basic oxygen furnace (BOF) slag in a high-gravity rotating packed bed (RPB) under various operational conditions was investigated. The effects of reaction time, reaction temperature, rotation speed and slurry flow rate on the CO(2) sequestration process were evaluated. The samples of reacted slurry were analyzed quantitatively using thermogravimetric analysis (TGA) and atomic absorption spectrometry (AAS) and qualitatively using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and transmission electron microscopy (TEM). The sequestration experiments were performed at a liquid-to-solid ratio of 20:1 with a flow rate of 2.5 L min(-1) of a pure CO(2) stream under atmospheric temperature and pressure. The results show that a maximum conversion of BOF slag was 93.5% at a reaction time of 30 min and a rotation speed of 750 rpm at 65°C. The experimental data were utilized to determine the rate-limiting mechanism based on the shrinking core model (SCM), which was validated by the observations of SEM and TEM. Accelerated carbonation in a RPB was confirmed to be a viable method due to its higher mass-transfer rate. PMID:22633879

Chang, E-E; Pan, Shu-Yuan; Chen, Yi-Hung; Tan, Chung-Sung; Chiang, Pen-Chi

2012-08-15

174

Mars Gravity and Topography Interpretations  

NASA Technical Reports Server (NTRS)

New models of the topography of Mars and its gravity field from the Mars Global Surveyor mission are shedding new light on the structure of the planet and the state of isostatic compensation. Gravity field observations over the flat northern hemisphere plains show a number of anomalies at the 100 to 200 mGal level that have no apparent manifestation in the surface topography. We believe that these anomalies are probably the result of ancient impacts and represent regions of denser material buried beneath the outer depositional crust. Similar anomalies are also found in the region of the north polar ice cap even though a gravity anomaly resulting from the 3 km high icecap has not been uniquely identified. This leads us to speculate that the ice cap is largely compensated and is older than the timescale of isostatic compensation, about 10(exp 15) years.

Zuber, Maria T.; Smith, David E.; Solomon, Sean C.; Phillips, Roger J.

1999-01-01

175

Adsorption behavior of pesticide methomyl on activated carbon in a high gravity rotating packed bed reactor.  

PubMed

High gravity rotating packed bed (HGRPB) reactor possesses the property of high mass transfer rate, which is expected to promote the adsorption rate for the process. In this study, HGRPB has been applied on adsorption removal of methomyl from solution, adopting the adsorbent of activated carbon F400. The influence of operating parameters of HGRPB on mass transfer such as the rotating speed (N(R)), the flow rate of solution (F(L)) and initial concentration of methomyl (C(b0)) were examined. The traditionally internal mass transfer models combined with Freundlich isotherm were used to predict the surface and effective diffusion coefficients. In addition, the results have also been compared with those obtained from the traditional basket stirred batch reactor (BBR). The results showed that the larger values of N(R) and F(L) enhanced the effective intraparticle diffusion and provided more accessible adsorption sites so as to result in lower equilibrium concentration in HGRPB system when compared to SBR system. The results of adsorption kinetics demonstrated that surface and effective diffusions were both significantly greater in HGRPB system instead of BBR system. Furthermore, the values of Bi(S) also manifested less internal mass transfer resistance in HGRPB system. The contribution ratio (R(F)) of the surface to pore diffusion mass transport showed that the larger contribution resulted from the surface diffusion in HGRPB system. Therefore, the results reasonably led to the conclusion that when the HGRPB system applied on the adsorption of methomyl on F400, the lower equilibrium concentration and faster internal mass transfer can be obtained so as to highly possess great potential to match the gradually stricter environmental standard. PMID:22482495

Chang, Chiung-Fen; Lee, Shu-Chi

2012-06-01

176

The high-level trigger of ALICE  

NASA Astrophysics Data System (ADS)

One of the main tracking detectors of the forthcoming ALICE Experiment at the LHC is a cylindrical Time Projection Chamber (TPC) with an expected data volume of about 75 MByte per event. This data volume, in combination with the presumed maximum bandwidth of 1.2 GByte/s to the mass storage system, would limit the maximum event rate to 20 Hz. In order to achieve higher event rates, online data processing has to be applied. This implies either the detection and read-out of only those events which contain interesting physical signatures or an efficient compression of the data by modeling techniques. In order to cope with the anticipated data rate, massive parallel computing power is required. It will be provided in form of a clustered farm of SMP-nodes, based on off-the-shelf PCs, which are connected with a high bandwidth low overhead network. This High-Level Trigger (HLT) will be able to process a data rate of 25 GByte/s online. The front-end electronics of the individual sub-detectors is connected to the HLT via an optical link and a custom PCI card which is mounted in the clustered PCs. The PCI card is equipped with an FPGA necessary for the implementation of the PCI-bus protocol. Therefore, this FPGA can also be used to assist the host processor with first-level processing. The first-level processing done on the FPGA includes conventional cluster-finding for low multiplicity events and local track finding based on the Hough Transformation of the raw data for high multiplicity events. PACS: 07.05.-t Computers in experimental physics - 07.05.Hd Data acquisition: hardware and software - 29.85.+c Computer data analysis

Tilsner, H.; Alt, T.; Aurbakken, K.; Grastveit, G.; Helstrup, H.; Lindenstruth, V.; Loizides, C.; Nystrand, J.; Roehrich, D.; Skaali, B.; Steinbeck, T.; Ullaland, K.; Vestbo, A.; Vik, T.

177

Regulation of high density lipoprotein levels  

SciTech Connect

An increasing awareness of the physiologic and pathologic importance of serum high density lipoproteins (HDL) has led to a large number of observations regarding factors which influence their concentrations. HDL consists of a heterogeneous collection of macromolecules with diverse physical properties and chemical constituents. While laboratory techniques have made it possible to measure HDL and their individual components, there are as yet large gaps in our knowledge of the biochemical mechanisms and clinical significance of changes in these laboratory parameters. In this review, current concepts of the structure and metabolism of HDL will be briefly summarized, and the factors influencing their levels in humans will be surveyed. 313 references.

Krauss, R.M.

1982-03-01

178

The effects of high level infrasound  

SciTech Connect

This paper will attempt to survey the current knowledge on the effects of relative high levels of infrasound on humans. While this conference is concerned mainly about hearing, some discussion of other physiological effects is appropriate. Such discussion also serves to highlight a basic question, 'Is hearing the main concern of infrasound and low frequency exposure, or is there a more sensitive mechanism'. It would be comforting to know that the focal point of this conference is indeed the most important concern. Therefore, besides hearing loss and auditory threshold of infrasonic and low frequency exposure, four other effects will be provided. These are performance, respiration, annoyance, and vibration.

Johnson, D.L.

1980-02-01

179

High-level waste qualification: Managing uncertainty  

SciTech Connect

A vitrification facility is being developed by the U.S. Department of Energy (DOE) at the West Valley Demonstration Plant (WVDP) near Buffalo, New York, where approximately 300 canisters of high-level nuclear waste glass will be produced. To assure that the produced waste form is acceptable, uncertainty must be managed. Statistical issues arise due to sampling, waste variations, processing uncertainties, and analytical variations. This paper presents elements of a strategy to characterize and manage the uncertainties associated with demonstrating that an acceptable waste form product is achieved. Specific examples are provided within the context of statistical work performed by Pacific Northwest Laboratory (PNL).

Pulsipher, B.A.

1993-09-01

180

Service Oriented Architecture for High Level Applications  

SciTech Connect

Standalone high level applications often suffer from poor performance and reliability due to lengthy initialization, heavy computation and rapid graphical update. Service-oriented architecture (SOA) is trying to separate the initialization and computation from applications and to distribute such work to various service providers. Heavy computation such as beam tracking will be done periodically on a dedicated server and data will be available to client applications at all time. Industrial standard service architecture can help to improve the performance, reliability and maintainability of the service. Robustness will also be improved by reducing the complexity of individual client applications.

Chu, Chungming; Chevtsov, Sergei; Wu, Juhao; /SLAC; Shen, Guobao; /Brookhaven

2012-06-28

181

Detection Method and Observed Data of High-energy Gamma Rays under the Influence of Quantum Gravity  

NASA Astrophysics Data System (ADS)

The interaction of high-energy particles affected by quantum gravity is argued from the experimental viewpoint of raising a question, ``our detection method for high-energy ?-rays supplies trustworthy observation data and we are now seeing the true image of the universe through high-energy ?-rays?" The modified dispersion relation (MDR) for particles' energy and momentum is applied to the equation of energy-momentum conservation in particle reactions, to study the restriction imposed on the kinematic state of high-energy particles by the Lorentz invariance violation (LIV) due to quantum gravity, as a function of the incident particle energy of the reaction. The result suggests that the interaction utilized for ?-ray detection is not free from the effect of quantum gravity when ?-ray energy is higher than 1013 ~ 1017 eV depending on models of MDR. Discussion is presented on the prospect of finding clear evidence of the LIV effect from ?-ray observations, as well as on the radiation and propagation mechanism of ?-rays under the influence of the LIV effect.

Kifune, T.

2014-05-01

182

High resolution local Moho determination using gravity inversion: A case study in Sri Lanka  

NASA Astrophysics Data System (ADS)

The seismic data incorporated in global Moho models are sparse and therefore the interpolation of global Moho depths on a local area may give unrealistic results, especially in regions without adequate seismic information. Gravity inversion is a useful tool that can be used to determine Moho depths in the mentioned regions. This paper describes an interactive way of local Moho depth determination using the gravity inversion method constrained with available seismic data. Before applying inversion algorithms, the Bouguer gravity data is filtered in various stages that reduce the potential bias usually expected in Moho depth determination using gravity methods with constant density contrast assumption. A test area with reliable seismic data is used to validate the results of Moho computation, and subsequently the same computation procedure is applied to the Sri Lankan region. The results of the test area are in better agreement with seismically determined Moho depths than those obtained by global Moho models. In the Sri Lankan region, Moho determination reveals a fairly uniform thin crust of average thickness around 20 km. The overall result suggests that our gravity inversion method is robust and may be suitable for local Moho determination in virgin regions, especially those without sufficient seismic data.

Prasanna, H. M. I.; Chen, W.; ?z, H. B.

2013-09-01

183

The effects of gravity level during directional solidification on the microstructure of hypermonotectic Al-In-Sn alloys  

NASA Technical Reports Server (NTRS)

Five hypermonotectic Al-In-Sn compositions were directionally solidified in a Bridgman-type furnace at normal gravity and during aircraft low-gravity maneuvers. The tendency of the Al-30In alloy to form an indium-rich band at the start of unidirectional growth (SUG) made it difficult to study the integration of L sub 2 into the solidification interface. Hypermonotectic compositions closer to monotectic slightly hypermonotectic caused only a partial band on L sub 2 to form at SUG and allowed the study of such variables as gravity, composition, and monotectic dome height on integration of excess L sub 2 into the solid plus L sub 2 interface. It was found that formation of aligned composite structures for the Al-In-Sn system is not only a function of G and R but also of the degree to which the composition varies from monotectic. Most of the aligned fibrous structures formed from hypermonotectic Al-In-Sn had spacings that were of the order of irregular fibrous structures reported for on monotectic Al-In-Sn. The spacings for the large fibers and aligned globules found for ground and low-gravity processed Al-In-18-Sn-22, respectively, were significantly larger than the others measured and were of the order expected for cell spacings under the growth conditions utilized. It was found that the integration into the solidification front of excess L sub 2 in low gravity was a function of the Sn composition of the alloy.

Curreri, P. A.; Kaukler, W. F.

1986-01-01

184

The ALICE electromagnetic calorimeter high level triggers  

NASA Astrophysics Data System (ADS)

The ALICE (A Large Ion Collider Experiment) detector yields a huge sample of data from different sub-detectors. On-line data processing is applied to select and reduce the volume of the stored data. ALICE applies a multi-level hardware trigger scheme where fast detectors are used to feed a three-level (L0, L1, and L2) deep chain. The High-Level Trigger (HLT) is a fourth filtering stage sitting logically between the L2 trigger and the data acquisition event building. The EMCal detector comprises a large area electromagnetic calorimeter that extends the momentum measurement of photons and neutral mesons up to pT = 250 GeV/c, which improves the ALICE capability to perform jet reconstruction with measurement of the neutral energy component of jets. An online reconstruction and trigger chain has been developed within the HLT framework to sharpen the EMCal hardware triggers, by combining the central barrel tracking information with the shower reconstruction (clusters) in the calorimeter. In the present report the status and the functionality of the software components developed for the EMCal HLT online reconstruction and trigger chain will be discussed, as well as preliminary results from their commissioning performed during the 2011 LHC running period.

Ronchetti, F.; Blanco, F.; Figueredo, M.; Knospe, A. G.; Xaplanteris, L.

2012-12-01

185

Exposure to unusually high indoor radon levels  

SciTech Connect

Unusually high indoor radon concentrations were reported in a small village in western Tyrol, Austria. The authors have measured the seasonal course of indoor radon concentrations in 390 houses of this village. 71% of houses in winter and 33% in summer, showed radon values on the ground floor above the Austrian action level of 400 Bq/cm[sup 3]. This proportion results in an unusually high indoor radon exposure of the population. The radon source was an 8,700-year-old rock slide of granite gneiss, the largest of the alpine crystalline rocks. It has a strong emanating power because its rocks are heavily fractured and show a slightly increased uranium content. Previous reports show increased lung cancer mortality, myeloid leukemia, kidney cancer, melanoma, and prostate cancer resulting from indoor radon exposure. However, many studies fail to provide accurate information on indoor radon concentrations, classifying them merely as low, intermediate, and high, or they record only minor increases in indoor radon concentrations. Mortality data for 1970-91 were used to calculate age and sex standardized mortality rates (SMR) for 51 sites of carcinoma. The total population of Tyrol were controls. A significantly higher risk was recorded for lung cancer. The high SMR for lung cancer in female subjects is especially striking. Because the numbers were low for the other cancer sites, these were combined in one group to calculate the SMR. No significant increase in SMR was found for this group.

Rasheed, F.N. (International Centre for Diarrhoeal Disease Research, Dhaka (Bangladesh))

1993-03-27

186

High accuracy electronic material level sensor  

DOEpatents

The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: (1) a high accuracy time base that is referenced to a quartz crystal, (2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, (3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or ``ghost`` reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%. 4 figs.

McEwan, T.E.

1997-03-11

187

High accuracy electronic material level sensor  

DOEpatents

The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: 1) a high accuracy time base that is referenced to a quartz crystal, 2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, 3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or "ghost" reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%.

McEwan, Thomas E. (Livermore, CA)

1997-01-01

188

Technetium Chemistry in High-Level Waste  

SciTech Connect

Tc contamination is found within the DOE complex at those sites whose mission involved extraction of plutonium from irradiated uranium fuel or isotopic enrichment of uranium. At the Hanford Site, chemical separations and extraction processes generated large amounts of high level and transuranic wastes that are currently stored in underground tanks. The waste from these extraction processes is currently stored in underground High Level Waste (HLW) tanks. However, the chemistry of the HLW in any given tank is greatly complicated by repeated efforts to reduce volume and recover isotopes. These processes ultimately resulted in mixing of waste streams from different processes. As a result, the chemistry and the fate of Tc in HLW tanks are not well understood. This lack of understanding has been made evident in the failed efforts to leach Tc from sludge and to remove Tc from supernatants prior to immobilization. Although recent interest in Tc chemistry has shifted from pretreatment chemistry to waste residuals, both needs are served by a fundamental understanding of Tc chemistry.

Hess, Nancy J.

2006-06-01

189

Application of multistage continuous fermentation for production of fuel alcohol by very-high-gravity fermentation technology  

Microsoft Academic Search

  A fermentation system to test the merging of very-high-gravity (VHG) and multistage continuous culture fermentation (MCCF)\\u000a technologies was constructed and evaluated for fuel ethanol production. Simulated mashes ranging from 15% to 32% w\\/v glucose\\u000a were fermented by Saccharomyces cerevisiae and the dilution rates were adjusted for each glucose concentration to provide an effluent containing less than 0.3% w\\/v\\u000a glucose (greater

D P Bayrock; W Michael Ingledew

2001-01-01

190

Gravity effects obtained from global hydrology models in comparison with high precision gravimetric time series  

NASA Astrophysics Data System (ADS)

Water mass changes are a major source of variations in residual gravimetric time series obtained from the combination of observations with superconducting and absolute gravimeters. Changes in the local water storage are the main influence, but global variations contribute to the signal significantly. For three European gravity stations, Bad Homburg, Wettzell and Medicina, different global hydrology models are compared. The influence of topographic effects is discussed and due to the long-term stability of the combined gravity time series, inter-annual signals in model data and gravimetric observations are compared. Two sources of influence are discriminated, i.e., the effect of a local zone with an extent of a few kilometers around the gravimetric station and the global contribution beyond 50km. Considering their coarse resolution and uncertainties, local effects calculated from global hydrological models are compared with the in-situ gravity observations and, for the station Wettzell, with local hydrological monitoring data.

Wziontek, Hartmut; Wilmes, Herbert; Güntner, Andreas; Creutzfeldt, Benjamin

2010-05-01

191

Effect of melt convection at various gravity levels and orientations on the forces acting on a large spherical particle in the vicinity of a solidification interface  

NASA Astrophysics Data System (ADS)

Numerical modeling was undertaken to analyze the influence of both radial and axial thermal gradients on convection patterns and velocities during solidification of pure Al and an Al-4 wt% Cu alloy. The objective of the numerical task was to predict the influence of convective velocity on an insoluble particle near a solid/liquid (s/l) interface. These predictions were then be used to define the minimum gravity level ( g) required to investigate the fundamental physics of interactions between a particle and a s/l interface. This is an ongoing NASA funded flight experiment entitled "particle engulfment and pushing by solidifying interfaces (PEP)". Steady-state calculations were performed for different gravity levels and orientations with respect to the gravity vector. The furnace configuration used in this analysis is the quench module insert (QMI-1) proposed for the Material Science Research Facility (MSRF) on board the International Space Station (ISS). The general model of binary alloy solidification was based on the finite element code FIDAP. At a low g level of 10 -4g 0 ( g 0=9.8 m/s 2) maximum melt convection was obtained for an orientation of 90°. Calculations showed that even for this worst case orientation the dominant forces acting on the particle are the fundamental drag and interfacial forces.

Bune, Andris V.; Sen, Subhayu; Mukherjee, Sundeep; Catalina, Adrian; Stefanescu, Doru M.

2000-04-01

192

Effect of Melt Convection at Various Gravity Levels and Orientations on the Forces Acting on a Large Spherical Particle in the Vicinity of a Solidification Interface  

NASA Technical Reports Server (NTRS)

Numerical modeling was Undertaken to analyze the influence of both radial and axial thermal gradients on convection patterns and velocities claiming solidification of pure Al and an Al-4 wt% Cu alloy. The objective of the numerical task was to predict the influence of convective velocity on an insoluble particle near a solid/liquid (s/l) interface. These predictions were then be used to define the minimum gravity level (q) required to investigate the fundamental physics of interactions between a particle and a s/l interface. This is an ongoing NASA founded flight experiment entitled "particle engulfment and pushing by solidifying interfaces (PEP)". Steady-state calculations were performed for different gravity levels and orientations with respect to the gravity vector The furnace configuration used in this analysis is the quench module insert (QMI-1) proposed for the Material Science Research Facility (MSRF) on board the International Space Station (ISS). The general model of binary alloy solidification was based on the finite element code FIDAP. At a low g level of 10(exp -4) g(sub o) (g(sub o) = 9.8 m/square s) maximum melt convection was obtained for an orientation of 90 deg. Calculations showed that even for this worst case orientation the dominant forces acting on the particle are the fundamental drag and interfacial forces.

Bune, Andris V.; Sen, Subhayu; Mukherjee, Sundeep; Catalina, Adrian; Stefanescu, Doru M.

2000-01-01

193

Mars: Crustal Structure Inferred from Bouguer Gravity Anomalies  

Microsoft Academic Search

Bouguer gravity has been computed for the equatorial region of Mars by differencing free air gravity and the gravity predicted from topographic variations. The free air gravity was generated from an eighth-order set of spherical harmonic coefficients. The gravity from topographic variations was generated by integrating a two-dimensional Green's function over each contour level. The Bouguer gravity indicates crustal inhomogeneities

R. J. Phillips; R. S. Saunders; J. E. Conel

1973-01-01

194

High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding  

NASA Astrophysics Data System (ADS)

Geoid data are more sensitive to density distributions deep within the Earth, thus the data are useful for studying the internal processes of the Earth leading to formation of geological structures. In this paper, we present much improved version of high resolution (1' × 1') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites. The geoid map of the Indian Ocean is dominated by a significant low of -106 m south of Sri Lanka, named as the Indian Ocean Geoid Low (IOGL), whose origin is not clearly known yet. The residual geoid data are retrieved from the geoid data by removing the long-wavelength core-mantle density effects using recent spherical harmonic coefficients of Earth Gravity Model 2008 (EGM2008) up to degree and order 50 from the observed geoid data. The coefficients are smoothly rolled off between degrees 30-70 in order to avoid artifacts related to the sharp truncation at degree 50. With this process we observed significant improvement in the residual geoid data when compared to the previous low-spatial resolution maps. The previous version was superposed by systematic broad regional highs and lows (like checker board) with amplitude up to ±12 m, though the trends of geoid in general match in both versions. These methodical artifacts in the previous version may have arisen due to the use of old Rapp's geo-potential model coefficients, as well as sharp truncation of reference model at degree and order 50. Geoid anomalies are converted to free-air gravity anomalies and validated with cross-over corrected ship-borne gravity data of the Arabian Sea and Bay of Bengal. The present satellite derived gravity data matches well with the ship-borne data with Root Mean Square Error (RMSE) of 5.1-7.8 mGal, and this is found to be within the error limits when compared with other globally available satellite data. Spectral analysis of ship-borne and satellite data suggested that the satellite gravity data have a resolution down to 16-18 km. Further, the geoid, residual geoid and gravity anomalies are integrated with seismic data along two profiles in the Bay of Bengal and Arabian Sea, and inferences have been made in terms of density distributions at different depths. The new residual geoid anomaly map shows excellent correlation with regional tectonic features such as Sunda subduction zone, volcanic traces (Chagos-Laccadive, Ninetyeast and 85°E ridges) and mid-ocean ridge systems (Central Indian and Carlsberg ridges).

Sreejith, K. M.; Rajesh, S.; Majumdar, T. J.; Srinivasa Rao, G.; Radhakrishna, M.; Krishna, K. S.; Rajawat, A. S.

2013-01-01

195

Sensorimotor aspects of high-speed artificial gravity: III. Sensorimotor adaptation  

NASA Technical Reports Server (NTRS)

As a countermeasure to the debilitating physiological effects of weightlessness, astronauts could live continuously in an artificial gravity environment created by slow rotation of an entire spacecraft or be exposed to brief daily "doses" in a short radius centrifuge housed within a non-rotating spacecraft. A potential drawback to both approaches is that head movements made during rotation may be disorienting and nauseogenic. These side effects are more severe at higher rotation rates, especially upon first exposure. Head movements during rotation generate aberrant vestibular stimulation and Coriolis force perturbations of the head-neck motor system. This article reviews our progress toward distinguishing vestibular and motor factors in side effects of rotation, and presents new data concerning the rates of rotation up to which adaptation is possible. We have studied subjects pointing to targets during constant velocity rotation, because these movements generate Coriolis motor perturbations of the arm but do not involve unusual vestibular stimulation. Initially, reaching paths and endpoints are deviated in the direction of the transient lateral Coriolis forces generated. With practice, subjects soon move in straighter paths and land on target once more. If sight of the arm is permitted, adaptation is more rapid than in darkness. Initial arm movement trajectory and endpoint deviations are proportional to Coriolis force magnitude over a range of rotation speeds from 5 to 20 rpm, and there is rapid, complete motor adaptation at all speeds. These new results indicate that motor adaptation to high rotation rates is possible. Coriolis force perturbations of head movements also occur in a rotating environment but adaptation gradually develops over the course of many head movements.

DiZio, Paul; Lackner, James R.; Young, L. R. (Principal Investigator)

2002-01-01

196

Gravity waves in the middle atmosphere during the MaCWAVE winter campaign: evidence of mountain wave critical level encounters  

Microsoft Academic Search

Falling sphere and balloon wind and temperature data from the MaCWAVE winter campaign, which was conducted in northern Scandinavia during January 2003, are analyzed to investigate gravity wave characteristics in the stratosphere and mesosphere. There were two stratospheric warming events occurring during the campaign, one having a maximum temperature perturbation at ~45 km during 17-19 January, and the other having

L. Wang; D. C. Fritts; B. P. Williams; R. A. Goldberg; F. J. Schmidlin; U. Blum

2006-01-01

197

Effects of gravity level during directional solidification on the microstructure of hypermonotectic Al-In-Sn alloys  

SciTech Connect

Five hypermonotectic Al-In-Sn compositions were directionally solidified in a Bridgman-type furnace at normal gravity and during aircraft low-gravity maneuvers. The tendency of the Al-30In alloy to form an indium-rich band at the start of unidirectional growth (SUG) made it difficult to study the integration of L/sub 2/into the solidification interface. Hypermonotectic compositions closer to monotectic slightly hypermonotectic caused only a partial band on L/sub 2/to form at SUG and allowed the study of such variables as gravity, composition, and monotectic dome height on integration of excess L /sub 2/into the solid plus L/sub 2/interface. It was found that formation of aligned composite structures for the Al-In-Sn system is not only a function of G and R but also of the degree to which the composition varies from monotectic. Most of the aligned fibrous structures formed from hypermonotectic Al-In-Sn had spacings that were of the order of irregular fibrous structures reported for on monotectic Al-In-Sn. The spacings for the large fibers and aligned globules found for ground and low-gravity processed Al-In-18-Sn-22, respectively, were significantly larger than the others measured and were of the order expected for cell spacings under the growth conditions utilized. It was found that the integration into the solidification front of excess L/sub 2/in low gravity was a function of the Sn composition of the alloy.

Curreri, P.A.; Kaukler, W.F.

1986-11-01

198

Gravity Waves  

article title:  Gravity Waves Ripple over Marine Stratocumulus Clouds   ... Imaging SpectroRadiometer (MISR), a fingerprint-like gravity wave feature occurs over a deck of marine stratocumulus clouds. Similar ...

2013-04-19

199

Goose Bay radar observations of Earth-reflected, atmospheric gravity waves in the high-latitude ionosphere  

SciTech Connect

In the late fall and early winter, The Johns Hopkins University HF radar at Goose Bay, Labrador, observes the effects of atmospheric gravity waves on radar transmissions that are obliquely reflected from the ionosphere and subsequently backscattered from the Earth's surface. The waves exist under a wide variety of geomagnetic conditions; however, they are particularly noticeable under quiet conditions (O {le} Kp {le} 1 +). The clearest signatures of the waves are spatially localized enhancements in the backscattered power and quasi-periodic fluctuations in the backscatter powers, Doppler velocities, and reflection heights. The waves are generally observed during daylight hours and propagate equatorward from regions of high-latitude ionospheric backscatter that are located near the ionospheric convection reversal boundary. The gravity waves appear to be generated just equatorward of the dayside flow-reversal boundary in the vicinity of the auroral electrojet at altitudes of 115 to 135 km and propagate approximately perpendicular to the boundary along azimuths ranging from 156{degree} to 180{degree}. The waves propagate obliquely downward through the lower atmosphere until they are reflected by the Earth's surface back into the upper atmosphere. The frequencies associated with these gravity waves cover the range of 0.3 to 0.6 mHz, with wavelengths of 300 to 500 km, and with average phase velocities of 110 to 180 m/s. The maximum phase speeds are 270 to 300 m/s, which is slightly less than the speed of sound in the lower atmosphere. Poleward-propagating gravity waves are sometimes observed under disturbed conditions when the polar cap and convection reversal boundary have expanded equatorward.

Samson, J.C.; Greenwald, R.A.; Ruohoniemi, J.M.; Frey, A.; Baker, K.B. (Johns Hopkins Univ., Laurel, MD (USA))

1990-06-01

200

HIGH LEVEL RF FOR THE SNS RING.  

SciTech Connect

A high level RF system (HLRF) consisting of power amplifiers (PA's) and ferrite loaded cavities is being designed and built by Brookhaven National Laboratory (BNL) for the Spallation Neutron Source (SNS) project. It is a fixed frequency, two harmonic system whose main function is to maintain a gap for the kicker rise time. Three cavities running at the fundamental harmonic (h=l) will provide 40 kV and one cavity at the second harmonic (h=2) will provide 20 kV. Each cavity has two gaps with a design voltage of 10 kV per gap and will be driven by a power amplifier (PA) directly adjacent to it. The PA uses a 600kW tetrode to provide the necessary drive current. The anode of the tetrode is magnetically coupled to the downstream cell of the cavity. Drive to the PA will be provided by a wide band, solid state amplifier located remotely. A dynamic tuning scheme will be implemented to help compensate for the effect of beam loading.

ZALTSMAN,A.; BLASKIEWICZ,M.; BRENNAN,J.; BRODOWSKI,J.; METH,M.; SPITZ,R.; SEVERINO,F.

2002-06-03

201

Integration of P- and SH-wave high-resolution seismic reflection and micro-gravity techniques to improve interpretation of shallow subsurface structure: New Madrid seismic zone  

USGS Publications Warehouse

Shallow high-resolution seismic reflection surveys have traditionally been restricted to either compressional (P) or horizontally polarized shear (SH) waves in order to produce 2-D images of subsurface structure. The northernmost Mississippi embayment and coincident New Madrid seismic zone (NMSZ) provide an ideal laboratory to study the experimental use of integrating P- and SH-wave seismic profiles, integrated, where practicable, with micro-gravity data. In this area, the relation between "deeper" deformation of Paleozoic bedrock associated with the formation of the Reelfoot rift and NMSZ seismicity and "shallower" deformation of overlying sediments has remained elusive, but could be revealed using integrated P- and SH-wave reflection. Surface expressions of deformation are almost non-existent in this region, which makes seismic reflection surveying the only means of detecting structures that are possibly pertinent to seismic hazard assessment. Since P- and SH-waves respond differently to the rock and fluid properties and travel at dissimilar speeds, the resulting seismic profiles provide complementary views of the subsurface based on different levels of resolution and imaging capability. P-wave profiles acquired in southwestern Illinois and western Kentucky (USA) detect faulting of deep, Paleozoic bedrock and Cretaceous reflectors while coincident SH-wave surveys show that this deformation propagates higher into overlying Tertiary and Quaternary strata. Forward modeling of micro-gravity data acquired along one of the seismic profiles further supports an interpretation of faulting of bedrock and Cretaceous strata. The integration of the two seismic and the micro-gravity methods therefore increases the scope for investigating the relation between the older and younger deformation in an area of critical seismic hazard. ?? 2006 Elsevier B.V. All rights reserved.

Bexfield, C. E.; McBride, J. H.; Pugin, A. J. M.; Ravat, D.; Biswas, S.; Nelson, W. J.; Larson, T. H.; Sargent, S. L.; Fillerup, M. A.; Tingey, B. E.; Wald, L.; Northcott, M. L.; South, J. V.; Okure, M. S.; Chandler, M. R.

2006-01-01

202

Turbulence and high-frequency variability in a deep gravity current outflow  

NASA Astrophysics Data System (ADS)

Intensive sampling of the deep Mediterranean outflow 70 km W of the Strait of Gibraltar reveals a strong, tidally modulated gravity current embedded with large-amplitude oscillations and energetic turbulence. The flow appears to be hydraulically controlled at a small topographic constriction, with turbulence and internal waves varying together and increasing dramatically downstream of the choke point. These data suggest that a significant fraction of energy dissipation, mixing, and entrainment stress in gravity currents may occur in localized regions controlled by time-varying flow interactions with fine-scale topography. These findings highlight the important role of processes that are not resolved by global climate models (GCMs), which do not contain tides or mixing due to fine-scale topographic interactions.

Nash, Jonathan D.; Peters, Hartmut; Kelly, Samuel M.; Pelegrí, Josep L.; Emelianov, Mikhail; Gasser, Marc

2012-09-01

203

On the facet-skeletal transition of snow crystals - Experiments in high and low gravity  

NASA Astrophysics Data System (ADS)

A laboratory investigation of the influence of air velocity on the growth of columnar ice crystals from the vapor over the range -3 to -5 C shows that the linear growth velocity increases and that columns transform to sheath crystals or needles as air velocity increases from a few cm/s to 40 cm/s. Comparison with a similar transition of plates to dendrites shows that, macroscopically, in both cases the facets sprout rounded tips at a critical velocity which is lower for higher ambient supersaturation. Studies in low gravity show that chamber scale convection under normal gravity may have significant influence on growth even in the absence of an imposed air velocity. Falling snow crystals become more skeletal in shape as they grow and fall with increasing velocity. This development depends critically on temperature (+ or - 0.5 C) and demonstrates that the snow crystal shape is even more dependent on environmental growth conditions that previously thought.

Alena, T.; Hallett, J.; Saunders, C. P. R.

1990-07-01

204

Network congestion analysis of gravity generated models  

NASA Astrophysics Data System (ADS)

The network topology has lately proved to be critical to the appearance of traffic congestion, with scale-free networks being the less affected at high volumes of traffic. Here, the congestion dynamics are investigated for a class of networks that has experienced a resurgence of interest, the networks based on the gravity model. In addition, supplementary to the standard paradigm of uniform traffic volumes between randomly interacting node pairs, more realistic gravity traffic patterns are used to simulate the flows in the network. Results indicate that depending on the traffic pattern, the networks have different tolerance to congestion. Experiment simulation shows that the topologies created on the basis of the gravity model suffer less from congestion than the random, the scale-free or the Jackson-Rogers ones under both random and gravity traffic patterns. The congestion level is found to be approximately correlated with the network clustering coefficient in the case of random traffic, whereas in the case of gravity traffic such a correlation is not a trivial one. Other basic network properties such as the average shortest path and the diameter are seen to correlate fairly well with the congestion level. Further investigation on the adjustment of the gravity model parameters indicates particular sensitivity to network congestion. This work may have practical implications for designing traffic networks with both reasonable budget and good performance.

Maniadakis, Dimitris; Varoutas, Dimitris

2014-07-01

205

Estimating gravity wave parameters from oblique high-frequency backscatter: Modeling and analysis  

NASA Technical Reports Server (NTRS)

A new technique for estimating electron density perturbation amplitudes of traveling ionospheric disturbances (TIDs), using HF radar data, is presented. TIDs are observed in HF radar data as enhancements of the ground-scattered power which propagate through the radar's field of view. These TIDs are the ionospheric manifestation of atmospheric acoustic-gravity waves. TID electron density perturbation amplitudes were estimated by simulating the radar returns, using HF ray tracing through a model ionosphere perturbed by a model gravity wave. The simulation determined the return power in the ground-scattered portion of the signal as a function of range, and this was compared to HF radar data from the Goose Bay HF radar at a time when evidence of gravity waves was present in the data. By varying the amplitude of the electron density perturbation in the model it was possible to estimate the perturbation of the actual wave. It was found that the perturbations that are observed by the Goose Bay HF radar are of the order of 20% to 35%. It was also found that the number of observable power enhancements, and the relative amplitudes of these enhancements, depended on the vertical thickness of the gravity wave's source region. From the simulations and observations it was estimated that the source region for the case presented here was approximately 20 km thick. In addition, the energy in the wave packet was calculated and compared to an estimate of the available energy in the source region. It was found that the wave energy was about 0.2% of the estimated available source region energy.

Bristow, W. A.; Greenwald, R. A.

1995-01-01

206

Are polar cap gravity waves a heat source for the high-latitude thermosphere?  

NASA Astrophysics Data System (ADS)

Ground based measurements of thermospheric temperatures from Mawson, Antarctica, often show a marked spatial gradient, with data taken poleward of the discrete auroral oval up to 200 K or more warmer than measurements taken in or equatorward of the oval. This region of increased temperature is identified as the polar cap. We suggest a possible contribution to polar cap heating may be from thermospheric gravity waves.

Innis, J. L.; Greet, P. A.; Dyson, P. L.

207

Complex Lunar Craters Mapped by High-Resolution GRAIL Gravity Data  

NASA Astrophysics Data System (ADS)

The Gravity Recovery and Interior Laboratory (GRAIL) mission [1] has successfully completed its three-month primary mission to directly measure lunar gravity. These data are of sufficient resolution and accuracy to address problems that have traditionally been in the realm of surface geologists. Herein, we report on an investigation of the subsurface structure of complex lunar impact craters and their associated continuous ejecta blankets using the GRAIL gravity data in conjunction with topography derived from Lunar Orbiter Laser Altimeter (LOLA) data [2]. We use these data to understand the initial state of the brecciated and fractured zone associated with complex crater formation and its dependence on crater size [3,4], the subsequent evolution of these complex craters, and the bulk density of the ejecta blankets associated with them. [1] Zuber, M., 37th COSPAR Scientific Assembly, (2008) [2] Zuber M. T. et al., Space Sci Rev 150, (2010) [3] Pilkington, M. and R. A. F. Grieve, Reviews of Geophysics 30, (1992) [4] Melosh, H. J., Oxford Monographs on Geology and Geophysics 11, (1989)

Soderblom, J. M.; Zuber, M. T.; Miljkovic, K.; Melosh, H. J.

2012-12-01

208

Meandarra Gravity Ridge: symmetry elements of the gravity anomaly and its relationship to the Bowen–Gunnedah–Sydney basin system  

Microsoft Academic Search

The Meandarra Gravity Ridge is one of the major gravity features in eastern Australia. The source(s) for this gravity anomaly is problematic because the ridge, a gravity high, coincides for much of its length with the thickest parts of the Bowen and Gunnedah Basins, areas that would normally be expected to be regional gravity lows. Furthermore, the Meandarra Gravity Ridge

A. A. Krassay; R. J. Korsch; B. J. Drummond

2009-01-01

209

Investigation of nocturnal low-level jet-generated gravity waves over Oklahoma City during morning boundary layer transition period using Doppler wind lidar data  

NASA Astrophysics Data System (ADS)

Low-level jet (LLJ)-generated gravity waves were observed over Oklahoma City by a scanning Doppler wind lidar during the transition periods of atmospheric boundary layer (ABL) from stable to convective conditions in the mornings after sunrise. The temperature profiles had a multilayer structure with a shallow neutral layer immediately above the ground and a stable cap layer above the neutral layer. The wind profiles exhibited a typical shape of a LLJ with nearly linear growth of wind speed with respect to height, and maximum wind speed occurred at the top of the stable cap layer. The average wavelength and its relation with mean wind and temperature profiles are characterized with data from Doppler wind lidar, radiosonde, and wind profiler. A linear stability analysis was performed to check the stratification conditions for wave occurrence. The wind signals from sonic anemometers near the ground were separated into waves and turbulence parts using a wavelet decomposition method, and the momentum fluxes due to the wave motions and turbulence were computed. The downward gravity wave momentum flux was 1.5 to 3.0 times of turbulent momentum flux. The analysis indicated that gravity wave momentum transport from the stable cap layer downward is one of the mechanisms of stable-to-convective transition in the LLJ-dominated ABL.

Wang, Yansen; Creegan, Edward; Felton, Melvin; Ligon, David; Huynh, Giap

2013-01-01

210

Coordinated Parallelizing Compiler Optimizations and High-Level Synthesis  

Microsoft Academic Search

We present a framework for high-level synthesis that enables the designer to explore the best choice of source level and low level parallelizing transformations for improved synthesis. Within this framework, we implemented a methodology that applies a set of parallelizing code transfor- mations, both at the source level and during scheduling. A designer can use these transformations to optimize high-level

SUMIT GUPTA; Alex Nicolau; Rajesh Gupta

2002-01-01

211

Proof of concept and performance optimization of high gravity batch-type centrifugal dryer for dewatering fine coal  

SciTech Connect

The primary objective of the project was to assemble, analyze and make use of those data that could help to clearly identify, optimize and confirm the technical and economic advantages that the new high gravity centrifugal dryer technology can provide to the coal industry and to end users. Other objectives were: to confirm the feasibility of the dryer for drying coals from a number of different seams; to use the data base for optimizing the dryer's systems, and: to produce projected technical and economic comparisons with thermal dryers as applied to an existing coal processing plant flow sheet. (JL)

Smith, L.B.; Durney, T.

1991-01-01

212

Feeling Gravity's Pull: Gravity Modeling. The Gravity Field of Mars  

Microsoft Academic Search

Most people take the constant presence of gravitys pull for granted. However, the Earth's gravitational strength actually varies from location to location. This variation occurs because mass, which influences an object's gravitational pull, is not evenly distributed within the planet. Changes in topography, such as glacial movement, an earthquake, or a rise in the ocean level, can subtly affect the

Frank Lemoine; David Smith; David Rowlands; Maria Zuber; G. Neumann; Douglas Chinn; D. Pavlis

2000-01-01

213

Point stability at shallow depths: experience from tilt measurements in the Lower Rhine Embayment, Germany, and implications for high-resolution GPS and gravity recordings  

NASA Astrophysics Data System (ADS)

From 1996 to 1999, we have studied ground tilts at depths of between 2m and 5m at three sites in the Lower Rhine Embayment (LRE), western Germany. The LRE is a tectonically active extensional sedimentary basin roughly 50km×100km. The purpose of the tilt measurements was (a) to provide insight into the magnitude, nature and variability of background tilts and (b) to assess possible limitations of high-resolution GPS campaigns and microgravity surveys due to natural ground deformation. The tilt readings, sensed by biaxial borehole tiltmeters of baselength 0.85m, cover a frequency range from 10-8Hz to 10-2Hz (periods from minutes to years). Assuming that the tilt signals represent ground displacements on a scale typically not larger than several times the tiltmeters' baselength, and that tilt signals at shallow depth could in a simple geometric way be related to changes in surface elevation and gravity, we try to estimate the magnitude level of point movements and corresponding Bouguer gravity effects that is generally not surpassed. The largest tilt signals observed were some +/-50µradyr-1. If they were observable over a ground section of extension, e.g. 10m, the converted rates may correspond to about +/-0.5mm per 10myr-1 in vertical ground displacement, and +/-0.1µgalyr-1 in Bouguer gravity effect, respectively. Large signals are mostly related to seasonal effects, probably linked to thermomechanical strain. Other causes of ground deformation identified include seepage effects after rainfalls (order of +/-10µrad) and diurnal strains due to thermal heating and/or fluctuations in the water consumption of nearby trees (order of +/-1µrad). Episodic step-like tilt anomalies with amplitudes up to 22µrad at one of the observation sites might reflect creep events associated to a nearby active fault. Except for short-term ground deformation caused by the passage of seismic waves from distant earthquakes, amplitudes of non-identified tilt signals in the studied frequency range seem not to exceed +/-2µrad. As the larger tilt signals are close to the precision achieved with modern GPS systems and superconducting gravimeters when converted into height and gravity changes, further enhancement in resolution of these techniques may require simultaneous recording of local ground deformation at the observation sites.

Kümpel, H.-J.; Lehmann, K.; Fabian, M.; Mentes, Gy.

2001-09-01

214

High-accuracy fiber optic level sensor  

Microsoft Academic Search

This paper describes a novel fiber-optic level sensor designed to measure the level of benzene, diesel oil and other chemical liquid discretely or continuously. It is an intensity-modulated on-off switching sensor whose operating principle is based on the frustrated-total-internal- reflection effect caused by the refraction index change of the surrounding medium. The sensor head is made from standard multi-mode communication

Liang Ren; Qingxu Yu

2002-01-01

215

Selection from Industrial Lager Yeast Strains of Variants with Improved Fermentation Performance in Very-High-Gravity Worts?  

PubMed Central

There are economic and other advantages if the fermentable sugar concentration in industrial brewery fermentations can be increased from that of currently used high-gravity (ca. 14 to 17°P [degrees Plato]) worts into the very-high-gravity (VHG; 18 to 25°P) range. Many industrial strains of brewer's yeast perform poorly in VHG worts, exhibiting decreased growth, slow and incomplete fermentations, and low viability of the yeast cropped for recycling into subsequent fermentations. A new and efficient method for selecting variant cells with improved performance in VHG worts is described. In this new method, mutagenized industrial yeast was put through a VHG wort fermentation and then incubated anaerobically in the resulting beer while maintaining the ?-glucoside concentration at about 10 to 20 g·liter?1 by slowly feeding the yeast maltose or maltotriose until most of the cells had died. When survival rates fell to 1 to 10 cells per 106 original cells, a high proportion (up to 30%) of survivors fermented VHG worts 10 to 30% faster and more completely (residual sugars lower by 2 to 8 g·liter?1) than the parent strains, but the sedimentation behavior and profiles of yeast-derived flavor compounds of the survivors were similar to those of the parent strains.

Huuskonen, Anne; Markkula, Tuomas; Vidgren, Virve; Lima, Luis; Mulder, Linda; Geurts, Wim; Walsh, Michael; Londesborough, John

2010-01-01

216

Observation and modeling of Na density and OH airglow temperature and intensity perturbations by a gravity wave approaching a critical level  

NASA Astrophysics Data System (ADS)

Atmospheric gravity waves at a broad range of temporal and spatial scales are frequently observed in MLT airglow imaging experiments. Airglow data provide significant insight into gravity wave propagation, directionality, and seasonality, and allow estimations of wave fluxes [e.g., Swenson et al., JGR, 104(D6), 1999]. The USU CEDAR Mesospheric Temperature Mapper (MTM) is a specialized CCD airglow imaging system, which was operated at Maui MALT from November 2001 to December 2006. The MTM captures OH(6,2) and O2(0,1) emissions intensities and associated rotational temperatures. The MTM has been used previously to assess zenith temperatures, showing close agreement with simultaneous lidar temperature data [Zhao et al., J. Geophys. Res., 110, D09S07, 2005]. It is additionally able to reveal two-dimensional structure of intensity and temperature perturbations associated with small-scale gravity waves. Here we investigate the vertical and horizontal structure of a small-scale gravity wave (~18 minute period and ~37 km horizontal wavelength) captured by the Maui MTM on April 11, 2002. The event was strongly visible in the OH(6,2) image data, showing intensity perturbations ~ 5-10 %, however relatively weak in the O2 data. Lidar temperatures and winds suggest the presence of a critical level shortly above ~90 km, which would have contributed to increased dissipation, and reduced detectability, due to small vertical scale. Using imaged intensity and rotational temperature data, along with evolving Na lidar data, we reconstruct and simulate the wave event under realistic ambient conditions using a suite of numerical models. Hydroxyl photochemistry and dynamics of O3, H, O, and Na densities are obtained with a two-dimensional nonlinear numerical model for gravity wave dynamics [Snively and Pasko, JGR, 113, A06303, 2008], allowing direct comparison of OH(6,2) intensity and brightness-weighted temperature perturbations [e.g., Makhlouf et al., JGR, 100(D6), 11289, 1995]. The strong sheared wind flow leads to dramatic variations of wave characteristics throughout the observable region, explaining the strong OH emission and relatively weak O2 emission. Krassovsky ratios and integrated cancellation effects of the modeled and observed airglow signatures are investigated, finding significant agreement, and inferred wave amplitude measurements are compared with modeled wave characteristics. Implications for wave momentum flux calculations from lidar and airglow data are discussed.

Snively, J. B.; Pautet, P.; Taylor, M. J.; Swenson, G. R.

2009-12-01

217

Clear and measurable signature of modified gravity in the galaxy velocity field.  

PubMed

The velocity field of dark matter and galaxies reflects the continued action of gravity throughout cosmic history. We show that the low-order moments of the pairwise velocity distribution v_{12} are a powerful diagnostic of the laws of gravity on cosmological scales. In particular, the projected line-of-sight galaxy pairwise velocity dispersion ?_{12}(r) is very sensitive to the presence of modified gravity. Using a set of high-resolution N-body simulations, we compute the pairwise velocity distribution and its projected line-of-sight dispersion for a class of modified gravity theories: the chameleon f(R) gravity and Galileon gravity (cubic and quartic). The velocities of dark matter halos with a wide range of masses would exhibit deviations from general relativity at the (5-10)? level. We examine strategies for detecting these deviations in galaxy redshift and peculiar velocity surveys. If detected, this signature would be a "smoking gun" for modified gravity. PMID:24949751

Hellwing, Wojciech A; Barreira, Alexandre; Frenk, Carlos S; Li, Baojiu; Cole, Shaun

2014-06-01

218

Clear and Measurable Signature of Modified Gravity in the Galaxy Velocity Field  

NASA Astrophysics Data System (ADS)

The velocity field of dark matter and galaxies reflects the continued action of gravity throughout cosmic history. We show that the low-order moments of the pairwise velocity distribution v12 are a powerful diagnostic of the laws of gravity on cosmological scales. In particular, the projected line-of-sight galaxy pairwise velocity dispersion ?12(r) is very sensitive to the presence of modified gravity. Using a set of high-resolution N-body simulations, we compute the pairwise velocity distribution and its projected line-of-sight dispersion for a class of modified gravity theories: the chameleon f(R) gravity and Galileon gravity (cubic and quartic). The velocities of dark matter halos with a wide range of masses would exhibit deviations from general relativity at the (5-10)? level. We examine strategies for detecting these deviations in galaxy redshift and peculiar velocity surveys. If detected, this signature would be a "smoking gun" for modified gravity.

Hellwing, Wojciech A.; Barreira, Alexandre; Frenk, Carlos S.; Li, Baojiu; Cole, Shaun

2014-06-01

219

Precision gravity detection - Gradiometry and/or radiometry  

NASA Technical Reports Server (NTRS)

Current knowledge concerning the earth's gravity field is limited to about 1500-2000 km resolution. However, the resolution of gravity anomalies having a spatial extent of 100-1000 km over the entire globe is needed for important geophysical and geodetic applications. In the near future satellite altimetry will be used to determine the ocean geoid at the 10 cm - 1 m level. In order to provide a similar level of resolutions over the land regions, there exists a need for utilizing new promising techniques such as gravity gradiometry and new radiometric measurements, viz., satellite-to-satellite tracking. Satellite-to-satellite tracking techniques have shown potential for improving the medium wavelength component of the gravity field. The gravity gradiometer has not yet been tested on board a satellite. The reported analysis includes a simplified theoretical model to compare the effectiveness of the gradiometer measurements and radiometric measurements for high resolution gravity field determination, and the direct estimation of local gravity anomalies represented by point masses using a simulated gravity gradiometer and satellite-to-satellite tracking data.

Ananda, M.

1977-01-01

220

Bouguer gravity anomalies in West Virginia  

Microsoft Academic Search

Four regional gravity features in West Virginia primarily reflect major basement structures, intra-basement ultramafics and Alleghenian structural grain. The central West Virginia gravity high corresponds with the southern and central West Virginia basement arches. The adjacent western West Virginia gravity low correlates with Rome trough basement structure. Calculated gravity profiles, magnetics, deep well and seismic data support the relationship of

B. R. Kulander; S. L. Dean

1985-01-01

221

Communicating with High-Level Plans.  

National Technical Information Service (NTIS)

We discuss our experience with an interface that gives users the ability to directly represent and manipulate goals at several levels of detail. The interface is built into Bridge, a tutorial environment for novice programmers. The name comes from our int...

B. Liffick J. Bonar

1988-01-01

222

Information Fusion for High Level Situation Assessment and Prediction.  

National Technical Information Service (NTIS)

This is the final report for our AFOSR sponsored project: Information Fusion for High Level Situation Assessment and Prediction. Through this project, we developed a probabilistic framework for performing high level information fusion. In addition, we dev...

Q. Ji

2007-01-01

223

VHDL as Input for High-Level Synthesis  

Microsoft Academic Search

High-level synthesis is defined, and the feasibility of high-level synthesis from a behavioral, sequential description in VHDL (VHSIC hardware description language) is examined. It is seen that in some cases the semantics and descriptive power of the language create difficulties for high-level synthesis, and in other cases the high-level synthesis framework used imposes limitations. Restrictions in the form of rules

Raul Camposano; L. F. Saunders; R. M. Tabet

1991-01-01

224

ICONDENSATION: Unifying Low-Level and High-Level Tracking in a Stochastic Framework  

Microsoft Academic Search

. Tracking research has diverged into two camps; low-level approaches which are typically fast and robust but provide little fine-scale information, and high-level approaches which track complex deformations in high-dimensional spaces but must trade off speed against robustness. Real-time high-level systems perform poorly in clutter and initialisation for most high-level systems is either performed manually or by a separate module.

Michael Isard; Andrew Blake

1998-01-01

225

46 CFR 153.409 - High level alarms.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false High level alarms. 153.409 Section 153...Cargo Gauging Systems § 153.409 High level alarms. When Table 1 refers...cargo's containment system must have a high level alarm: (a) That gives an...

2010-10-01

226

46 CFR 153.409 - High level alarms.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false High level alarms. 153.409 Section 153...Cargo Gauging Systems § 153.409 High level alarms. When Table 1 refers...cargo's containment system must have a high level alarm: (a) That gives an...

2009-10-01

227

Lunar gravity field recovery: GRAIL simulation studies  

NASA Astrophysics Data System (ADS)

The NASA mission GRAIL (Gravity Recovery and Interior Laboratory) makes use of low-low Satellite-to-Satellite Tracking (ll-SST) between the two spacecraft GRAIL-A and GRAIL-B to determine a high-resolution gravity field solution of the Moon. The mission concept is inherited from the GRACE (Gravity Recovery and Climate Experiment) project, a space gravimetry mission mapping the terrestrial gravity field. Since the Moon is in synchronous rotation with the Earth, direct (radio) tracking of the satellites on the farside is impossible, but GRAIL provides global coverage of inter-satellite tracking data. Furthermore, ll-SST observations are much more sensitive to gravitational features than ground-based orbit tracking. Therefore, compared to previous missions, GRAIL enables a more accurate estimation of the lunar gravity field, with a much higher spectral and spatial resolution. The accurate knowledge of the lunar nearside and farside gravity is essential to improve the understanding of the Moon's interior structure and its thermal evolution. We conducted a series of sensitivity studies based on simulated orbit information (positions) and ll-SST measurements (ranges, range rates, range accelerations). Observations are simulated on the nearside as well as on the farside (1) during the time span of the GRAIL science phase, (2) for different orbit altitudes and varying separation distances, (3) for different orbit/ll-SST noise levels. Based on the simulated observations the spherical harmonic coefficients, which represent the lunar gravity field, are estimated using an integral equation approach. Observation simulation and parameter estimation is accomplished using the GROOPS (Gravity Recovery Object Orientated Programming System) software package.

Klinger, Beate; Baur, Oliver; Mayer-Gürr, Torsten; Yan, Jianguo

2013-04-01

228

Turbulence Investigations With High-Resolution Simulations of Dilute Suspension Particle-Laden Gravity Currents  

NASA Astrophysics Data System (ADS)

Gravity currents are very common in nature, either in atmosphere (due to sea-breeze fronts), in mountain avalanches (in airborne snow or debris flow), or in the ocean due to turbidity currents or river plumes (Simpson, 1982). In this numerical study, we focus on particle-laden hyperpycnal flows (negative-buoyancy), where the dynamics play a central role in the formation of hydrocarbon reservoirs (Meiburg & Kneller, 2009). Moreover, these particle-driven gravity currents are often extremely dangerous for the stability of submarine structures placed near the sea-floor (like pipelines or submarines cables). It is clear that the understanding of the physical mechanism associated with these currents and the correct prediction of their main features are of great importance for practical as well as theoretical purposes. For this numerical work, we are interested in the prediction of a mono-disperse dilute suspension particle-laden flow in the typical lock-exchange configuration. We consider only flat surfaces using DNS (Direct Numerical Simulation). Our approach takes into account the possibility of particles deposition but ignores erosion and/or re-suspension. Previous results for this kind of flows were obtained in laboratory experiments with Reynolds numbers up to 10400 (De Rooij & Dalziel, 2001), or by numerical simulations at moderate Reynolds numbers, up to 5000 for a 2D case (Nasr-Azadani, Hall & Meiburg, 2011) and up to 2236 for a 3D (Necker, Härtel, Kleiser & Meiburg, 2002) case with a Reynolds number based on the buoyancy velocity. It was shown that boundary conditions, initial lock configuration and different particle sizes can have a strong influence on the main characteristics of this kind of flows. The main objective of this numerical study is to undertake unprecedented simulations in order to focus on the turbulence and to investigate the effect of the Reynolds number in such flows. We want to investigate the turbulent mechanism in gravity currents such as local production and dissipation and their relationships with the main features of the flow for different Reynolds numbers, ranging from 2236 to 10000 for 2D and 3D cases. The main features of the flow will be related to the temporal evolution of the front location, sedimentation rate and the resulting streamwise deposit profiles. In particular, we will investigate the flow energy budget where the balance between kinetic and potential energy with dissipation (due to convective fluid motion and Stokes flow around particles) will be analysed in detail, using comparisons with previous experimental and numerical works.

Espath, L.; Pinto, L.; Laizet, S.; Silvestrini, J.; Scientific Team of DNS on Gravity Currents

2013-05-01

229

Period analysis at high noise level  

NASA Astrophysics Data System (ADS)

Analytical expressions are derived for the variances of three types of periodograms due to normal-distributed noise present in the data: the conventional Fourier spectrum, the method of Warner and Robinson (1972), and Jurkevich's method (1971). The equivalence of the Jurkevich method and that of Warner and Robinson is proved. The optimum phase cell number of the Warner-Robinson method is given; this number depends on the data length, signal form, and noise level. Results are illustrated by the analysis of two typical forms of light curves: an eclipsing type light curve and an RRa curve.

Kovacs, G.

1980-05-01

230

Fast Scintillators for High Radiation Levels.  

National Technical Information Service (NTIS)

This article is a review of ongoing developmental work to make scintillators a viable and important element of the next generation of high energy physics detector systems. Although the key problem is that of radiation tolerance, attention has to be paid t...

S. Majewski C. Zorn

2000-01-01

231

The reconnaissance gravity survey of Australia: Qualitative analysis  

Microsoft Academic Search

As a first step towards analysing Australia's gravity pattern and its correlation with the regional structure, the Bouguer anomaly field over Australia and its northwest continental shelf was divided into 96 regional gravity provinces. A gravity province is a region where the gravity field is characterised by uniformity of at least one property, such as contour trend, gravity level, or

A. R. Fraser; F. Darby; K. R. Vale

1977-01-01

232

Searching for quantum gravity with high-energy atmospheric neutrinos and AMANDA-II  

NASA Astrophysics Data System (ADS)

The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance (VLI) or quantum decoherence (QD). Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on VLI and QD parameters using a maximum likelihood method. Given the absence of new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.

Kelley, John Lawrence

2008-06-01

233

Impacts of Thermal and Wind structures on Mesospheric Short-period Gravity Wave Propagation at High Latitudes  

NASA Astrophysics Data System (ADS)

Mesospheric short-period (<1-hr) gravity waves are of great importance for dynamics in the mesosphere-lower thermosphere (MLT) region, and are typically measured by instruments capable of high temporal and/or spatial resolutions, such as lidars and airglow imagers. These waves have been studied extensively at low- and mid-latitudes where known wave sources are well established. The results show strong dependence on the background wind and temperature fields, which can act as a barrier prohibiting vertical propagation of the waves, as well as providing a ducted environment in which the waves can travel large horizontal distances. In fact, results show that up to 75% of these waves may exhibit ducted wave motion. Recent efforts to quantify the existence and nature of these waves over the Antarctic continent have lead to a long-term (10 years) data set obtained with airglow imagers. Our results suggest that these southern polar waves are predominantly freely propagating in the airglow region, in stark contrast to results at other latitudes. A new study in the Arctic enables a comparison between the two data sets. In this work, we investigate the propagation nature of the observed wave field and attempt to identify dominant source regions and potential sources of polar gravity waves through ray tracing.

Nielsen, Kim; Taylor, Michael J.; Siskind, David; Collins, Richard; Harvey, V. Lynn; Russell, James; Irving, Brita; Negale, Michael

2012-07-01

234

The high-level synthesis of digital systems  

Microsoft Academic Search

High-level synthesis systems start with an abstract behavioral specification of a digital system and find a register-transfer level structure that realizes the given behavior. The various tasks involved in developing a register-transfer level structure from an algorithmic level specification are described. In particular, it is shown how the high-level synthesis task can be decomposed into a number of distinct but

M. C. McFarland; A. C. Parker; R. Camposano

1990-01-01

235

High-level fusion based on conceptual graphs  

Microsoft Academic Search

Most of studies in the field of information fusion focus on the production of high-level information from low-level data. The challenge is then to fuse this high-level information to produce a global and coherent information. Another approach consists in interpreting data as high-level information and fuse it at once. Our approach relies on the use of conceptual graphs model. The

Claire Laudy; Jean-Gabriel Ganascia; Célestin Sedogbo

2007-01-01

236

Infrared Thermography in High Level Waste  

SciTech Connect

The Savannah River Site is a Department of Energy, government-owned, company-operated industrial complex built in the 1950s to produce materials used in nuclear weapons. Five reactors were built to support the production of nuclear weapons material. Irradiated materials were moved from the reactors to one of the two chemical separation plants. In these facilities, known as ''canyons,'' the irradiated fuel and target assemblies were chemically processed to separate useful products from waste. Unfortunately, the by-product waste of nuclear material production was a highly radioactive liquid that had to be stored and maintained. In 1993 a strategy was developed to implement predictive maintenance technologies in the Liquid Waste Disposition Project Division responsible for processing the liquid waste. Responsibilities include the processing and treatment of 51 underground tanks designed to hold 750,000 to1,300,000 gallons of liquid waste and operation of a facility that vitrifies highly radioactive liquid waste into glass logs. Electrical and mechanical equipment monitored at these facilities is very similar to that found in non-nuclear industrial plants. Annual inspections are performed on electrical components, roof systems, and mechanical equipment. Troubleshooting and post installation and post-maintenance infrared inspections are performed as needed. In conclusion, regardless of the industry, the use of infrared thermography has proven to be an efficient and effective method of inspection to help improve plant safety and reliability through early detection of equipment problems.

GLEATON, DAVIDT.

2004-08-24

237

Fermilab Tevatron high level rf accelerating systems  

SciTech Connect

Eight tuned rf cavities have been installed and operated in the F0 straight section of the Tevatron. Their mechanical placement along the beam line enables them to be operated for colliding beams as two independent groups of four cavities, group 1-4 accelerating antiprotons and group 5-8 accelerating protons. The only difference is that the spacing between cavities 4 and 5 was increased to stay clear of the F0 colliding point. The cavities can easily be rephased by switching cables in a low-level distribution system (fan-out) so that the full accelerating capability of all eight cavities can be used during fixed target operations. Likewise, the cables from capacitive probes on each cavity gap can be switched to proper lengths and summed in a fan-back system to give an rf signal representing the amplitude and phase as ''seen by the beam,'' separately for protons and antiprotons. Such signals have been used to phase lock the Tevatron to the Main Ring for synchronous transfer.

Kerns, Q.; Kerns, C.; Miller, H.; Tawser, S.; Reid, J.; Webber, R.; Wildman, D.

1985-06-01

238

Topographic and Isostatic Reductions for Use in Satellite Gravity Gradiometry  

Microsoft Academic Search

Gravity gradiometry is strongly sensitive to the gravity field induced by the topographic and isostatic masses of the Earth.\\u000a The downward continuation of the gravitational signals from satellite height to sea level is rather difficult because of the\\u000a high frequency behaviour of the combined topographic-isostatic effect. Therefore a topographic-isostatic reduction is proposed\\u000a in order to smooth the signals. Based on

F. Wild; B. Heck

239

Gravity model studies of Newberry Volcano, Oregon  

USGS Publications Warehouse

Newberry Volcano, a large Quaternary volcano located about 60 km east of the axis of the High Cascades volcanoes in central Oregon, has a coincident positive residual gravity anomaly of about 12 mGals. Model calculations of the gravity anomaly field suggest that the volcano is underlain by an intrusive complex of mafic composition of about 20-km diameter and 2-km thickness, at depths above 4 km below sea level. However, uplifted basement in a northwest trending ridge may form part of the underlying excess mass, thus reducing the volume of the subvolcanic intrusive. A ring dike of mafic composition is inferred to intrude to near-surface levels along the caldera ring fractures, and low-density fill of the caldera floor probably has a thickness of 0.7-0.9 km. The gravity anomaly attributable to the volcano is reduced to the east across a north-northwest trending gravity anomaly gradient through Newberry caldera and suggests that normal, perhaps extensional, faulting has occurred subsequent to caldera formation and may have controlled the location of some late-stage basaltic and rhyolitic eruptions. Significant amounts of felsic intrusive material may exist above the mafic intrusive zone but cannot be resolved by the gravity data. -Authors

Gettings, M. E.; Griscom, A.

1988-01-01

240

Interactions between Artificial Gravity, the Affected Physiological Systems, and Nutrition  

NASA Technical Reports Server (NTRS)

Malnutrition, either by insufficient supply of some nutrients or by overfeeding, has a profound effect on the health of an organism. Therefore, optimal nutrition is a necessity in normal gravity on Earth, in microgravity, and when applying artificial gravity to the human system. Reduced physical activity, such as observed in microgravity or bed rest, has an effect on many physiological systems, such as the cardiovascular, musculoskeletal, immune, and body fluids regulation systems. There is currently no countermeasure that is effective to counteract both the cardiovascular and musculoskeletal deconditioning when applied for a short duration (see Chapter 1). Artificial gravity therefore seems the simplest physiological approach to keep these systems intact. The application of intermittent daily dose of artificial gravity by means of centrifugation has often been proposed as a potential countermeasure against the physiological deconditioning induced by spaceflight. However, neither the optimal gravity level, nor its optimal duration of exposure have been enough studied to recommend a validated, effective, and efficient artificial gravity application. As discussed in previous chapters, artificial gravity has a very high potential to counteract any changes caused by reduced physical activity. The nutrient supply, which ideally should match the actual needs, will interact with these changes and therefore has also to be taken into account. This chapter reviews the potential interactions between these nutrients (energy intake, vitamins, minerals) and the other physiological systems affected by artificial gravity generated by an on-board short-radius centrifuge.

Heer, Martina; Baecker, Nathalie; Zwart, Sara; Smith, Scott

2006-01-01

241

Effects of particulate materials and osmoprotectants on very-high-gravity ethanolic fermentation by Saccharomyces cerevisiae.  

PubMed Central

The effects of osmoprotectants (such as glycine betaine and proline) and particulate materials on the fermentation of very high concentrations of glucose by the brewing strain Saccharomyces cerevisiae (uvarum) NCYC 1324 were studied. The yeast growing at 20 degrees C consumed only 15 g of the sugar per 100 ml from a minimal medium which initially contained 35% (wt/vol) glucose. Supplementing the medium with a mixture of glycine betaine, glycine, and proline increased the amount of sugar fermented to 30.5 g/100 ml. With such supplementation, the viability of the yeast cells was maintained above 80% throughout the fermentation, while it dropped to less than 12% in the unsupplemented controls. Among single additives, glycine was more effective than proline or glycine betaine. On incubating the cultures for 10 days, the viability decreased to only 55% with glycine, while it dropped to 36 and 27%, respectively, with glycine betaine and proline. It is suggested that glycine and proline, known to be poor nitrogen sources for growth, may serve directly or indirectly as osmoprotectants. Nutrients such as tryptone, yeast extract, and a mixture of purine and pyrimidine bases increased the sugar uptake and ethanol production but did not allow the population to maintain the high level of cell viability. While only 43% of the sugar was fermented in unsupplemented medium, the presence of particulate materials such as wheat bran, wheat mash insolubles, alumina, and soy flour increased sugar utilization to 68, 75, 81, and 82%, respectively.

Thomas, K C; Hynes, S H; Ingledew, W M

1994-01-01

242

Logical Traps in High-Level Knowledge and Information Fusion  

Microsoft Academic Search

In this paper, we are concerned with high-level information fusion, such as it is envisioned in JDL levels 4 and 5. More precisely, the focus is on decision and reasoning systems that must act in a rational and logical way from several knowledge and high-level information sources and databases. Whatever the selected knowledge and information representation languages in the sources

Éric Grégoire; CRIL CNRS

243

Cake: Enabling High-level SLOs on Shared Storage Systems.  

National Technical Information Service (NTIS)

Cake is a coordinated, multi-resource scheduler for shared distributed storage environments with the goal of achieving both high throughput and bounded latency. Cake uses a two-level scheduling scheme to enforce high-level service-level objectives (SLOs)....

A. Wang I. Stoica R. H. Katz S. Alspaugh S. Venkataraman

2012-01-01

244

High-precision Acceleration Measurement Systems for Space Applications  

Microsoft Academic Search

The unique micro-gravity environment in space has brought high-precision accelerometer numerous space applications, like the measurements of micro-gravity, the Earth's gravity, gravity gradient, and the research on atmospheric drag, solar radiation pressure, the Earth's diffuse reflection, and so on. This paper describes two systems for micro-acceleration measurement, one of which has been used to monitor the micro-gravity level in low-orbit

Furong Tang; Datong Xue; Jungang Lei; Yufeng Cheng

2002-01-01

245

Preliminary results of absolute and high-precision gravity measurements at the Nevada Test Site and vicinity, Nevada  

Microsoft Academic Search

Absolute gravity measurements were made at 4 sites in southern Nevada using the absolute gravity free-fall apparatus. Three of the sites are located on the Nevada Test Site at Mercury, Yucca Pass, and in northern Jackass Flats. The fourth site is at Kyle Canyon ranger station near Charleston Park where observed gravity is 216.19 mGal lower than at Mercury. Although

M. A. Zumberge; R. N. Harris; H. W. Oliver; G. S. Sasagawa; D. A. Ponce

1988-01-01

246

Effects of Body Orientation and Retinal Image Pitch on the Perception of Gravity-Referenced Eye Level (GREL)  

NASA Technical Reports Server (NTRS)

It has been asserted that the pitch orientation of a visual array and of an observer's body jointly determine the perception of GREL. The current study formally tests this assertion over an extended range with multiple combinations of visual and body pitch orientations. Ten subjects were individually secured in a Circolectric bed surrounded by a room (pitchroom) with walls that could be pitched at various angles with respect to gravity. The bed and the walls of the room were independently adjusted to each of five positions relative to gravitational vertical: -15, -7.5, 0, +7.5, and +15 degrees, yielding 25 combinations of body x room pitch angles, and retinal image pitch (RIP) conditions ranging from -30 to +30 degrees. Each subject set a target to apparent GREL while viewing it against a background of two electroluminescent strips on the outer edges of the far wall of the room. As determined by ANOVA, the orientation of the room, and its interaction with that of the observer, significantly altered GREL (p less than 0.01). Regression analysis showed that GREL was best described as a linear summation of the weighted independent contributions from a body-referenced mechanism (B) and a visual mechanism given by the orientation of the background array on the retina (RIP). The equation for this relationship is: GREL = .74 (B) +.64 (RIP) - 1.42; r-squared = .994.

Cohen, Malcolm M.; Guzy, Larry T.; Wade, Charles E. (Technical Monitor)

1994-01-01

247

A reconfigurable high level FPGA-based coprocessor  

Microsoft Academic Search

FPGA technology enjoys both the high performance of a dedicated hardware solution and the flexibility of software that is offered by its inherent reprogrammability feature. Image processing is one application area that can benefit greatly from FPGAs performance and flexibility. This paper presents the design and implementation of a high-level reconfigurable image coprocessor on FPGAs. The image coprocessor high level

S. Sukhsawas; K. Benkrid; D. Crookes

2003-01-01

248

Using High-Level Semantic Features in Video Retrieval  

Microsoft Academic Search

Extraction and utilization of high-level semantic features are critical for more effective video retrieval. However, the performance of video retrieval hasn't benefited much despite of the advances in high-level feature extraction. To make good use of high-level semantic features in video retrieval, we present a method called pointwise mutual informa- tion weighted scheme(PMIWS). The method makes a good judgment of

Wujie Zheng; Jianmin Li; Zhangzhang Si; Fuzong Lin; Bo Zhang

2006-01-01

249

Changes in water levels and storage in the High Plains Aquifer, predevelopment to 2009  

USGS Publications Warehouse

The High Plains aquifer underlies 111.8 million acres (175,000 square miles) in parts of eight States - Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. The area overlying the High Plains aquifer is one of the primary agricultural regions in the Nation. Water-level declines began in parts of the High Plains aquifer soon after the onset of substantial irrigation with groundwater from the aquifer (about 1950 and termed "predevelopment" in this fact sheet). By 1980, water levels in the High Plains aquifer in parts of Texas, Oklahoma, and southwestern Kansas had declined more than 100 feet (ft) (Luckey and others, 1981). In 1987, in response to declining water levels, Congress directed the U.S. Geological Survey (USGS), in collaboration with numerous Federal, State, and local water-resources entities, to assess and track water-level changes in the aquifer. This fact sheet summarizes changes in water levels and drainable water in storage in the High Plains aquifer from predevelopment to 2009. Drainable water in storage is the fraction of water in the aquifer that will drain by gravity and can be withdrawn by wells. The remaining water in the aquifer is held to the aquifer material by capillary forces and generally cannot be withdrawn by wells. Drainable water in storage is termed "water in storage" in this report. A companion USGS report presents more detailed and technical information about water-level and storage changes in the High Plains aquifer during this period (McGuire, 2011).

McGuire, V.L.

2011-01-01

250

Solar Wind Plasma Streams, High-Level Clouds and Extratropical Storms  

NASA Astrophysics Data System (ADS)

Time series of a high-level cloud area index (HCAI) based on infrared cloud amounts (cloud top pressure < 440 mb) extracted from the International Satellite Cloud Climatology Project (ISCCP) D1 dataset covering 22 years are constructed for various geographic sectors. The HCAI is defined as a percentage ratio of 280×280 km2 cells for which the high-level cloud amounts exceeded a given threshold; typical HCAI values range between 20-40% at mid latitudes. Time series of HCAI are used in superposed epoch analysis keyed by the arrival time of co-rotating solar wind streams from coronal holes. A statistically significant decrease of the mean HCAI around the arrival of stream-interaction regions at the leading edge of high-speed solar wind followed by an increase in HCAI to a maximum a few days later is found. The observed mean amplitude (< 3.0% in HCAI units) of the HCAI response to solar wind forcing depends on season, geographic latitude and longitude, and on the phase of the quasi-biennial oscillation (QBO) of the zonal winds in the tropical stratosphere. It is known that the QBO affects the global atmospheric circulation dynamics which in turn has an impact on propagation of atmospheric gravity waves (AGWs). It is suggested that solar- wind-generated auroral AGWs seeding convective instabilities in the mid-latitude troposphere contribute to formation of deep convective clouds and growth of extratropical cyclones and, if ducted to low latitudes, may influence the development of tropical cyclones. Although small in amplitude, the auroral gravity wave induced vertical lift combined with a horizontal or upward tilting flow in the warm frontal zone may release the moist symmetric instability, thus initiating slantwise convection. Mesoscale cloud/rain bands are observed in infrared satellite images of extratropical cyclones a few hours after the auroral AGWs are launched. Latent heat release associated with the mesoscale slantwise convection has been linked to explosive cyclogenesis. It is observed that major extratropical storms tend to occur within a few days of the arrival of the high-speed solar wind, which is a source of magneto-hydrodynamic waves that couple to the magnetosphere and generate auroral atmospheric gravity waves.

Prikryl, P.

2006-12-01

251

An underlying theory for gravity  

NASA Astrophysics Data System (ADS)

A new direction to understand gravity has recently been explored by considering classical gravity to be a derived interaction from an underlying theory. This underlying theory would involve new degrees of freedom at a deeper level, and it would be structurally different from classical gravitation. It may conceivably be a quantum theory or a non-quantum theory. The relation between this underlying theory and Einstein's gravity is similar to the connection between statistical mechanics and thermodynamics. We discuss the apparent lack of evidence of any quantum nature of spacetime and the meaning of quantum gravity in this context.

Ha, Y. K.

2014-03-01

252

DOE HIGH-LEVEL VITRIFIED WASTE DOSE CALCULATION  

SciTech Connect

The purpose of this engineering calculation is to provide the radiological dose at 5,000 meters from the surface facilities of the Monitored Geologic Repository (MGR) resulting from a drop of one High-Level Waste (HLW) canister containing vitrified high-level waste glass during handling operations in the Waste Handling Building (WHB). High-level vitrified wastes from Savannah River Site (SRS), Hanford Works, West Valley, New York, and Idaho National Engineering and Environmental Laboratory (INEEL) are evaluated. This calculation will provide input data for future safety analyses for handling of Department of Energy (DOE) high-level waste in the MGR.

J.A. Ziegler

1999-08-26

253

Quench cooling under reduced gravity.  

PubMed

We report quench cooling experiments performed with liquid O(2) under different levels of gravity, simulated with magnetic gravity compensation. A copper disk is quenched from 300 to 90 K. It is found that the cooling time in microgravity is very long in comparison with any other gravity level. This phenomenon is explained by the insulating effect of the gas surrounding the disk. A weak gas pressurization (which results in subcooling of the liquid with respect to the saturation temperature) is shown to drastically improve the heat exchange, thus reducing the cooling time (about 20 times). The effect of subcooling on the heat transfer is analyzed at different gravity levels. It is shown that this type of experiment cannot be used for the analysis of the critical heat flux of the boiling crisis. The film boiling heat transfer and the minimum heat flux of boiling are analyzed as functions of gravity and subcooling. PMID:23944546

Chatain, D; Mariette, C; Nikolayev, V S; Beysens, D

2013-07-01

254

Error analysis of the NGS' surface gravity database  

NASA Astrophysics Data System (ADS)

Are the National Geodetic Survey's surface gravity data sufficient for supporting the computation of a 1 cm-accurate geoid? This paper attempts to answer this question by deriving a few measures of accuracy for this data and estimating their effects on the US geoid. We use a data set which comprises {˜ }1.4 million gravity observations collected in 1,489 surveys. Comparisons to GRACE-derived gravity and geoid are made to estimate the long-wavelength errors. Crossover analysis and K-nearest neighbor predictions are used for estimating local gravity biases and high-frequency gravity errors, and the corresponding geoid biases and high-frequency geoid errors are evaluated. Results indicate that 244 of all 1,489 surface gravity surveys have significant biases {>}2 mGal, with geoid implications that reach 20 cm. Some of the biased surveys are large enough in horizontal extent to be reliably corrected by satellite-derived gravity models, but many others are not. In addition, the results suggest that the data are contaminated by high-frequency errors with an RMS of {˜ }2.2 mGal. This causes high-frequency geoid errors of a few centimeters in and to the west of the Rocky Mountains and in the Appalachians and a few millimeters or less everywhere else. Finally, long-wavelength ({>}3^{circ }) surface gravity errors on the sub-mGal level but with large horizontal extent are found. All of the south and southeast of the USA is biased by +0.3 to +0.8 mGal and the Rocky Mountains by -0.1 to -0.3 mGal. These small but extensive gravity errors lead to long-wavelength geoid errors that reach 60 cm in the interior of the USA.

Saleh, Jarir; Li, Xiaopeng; Wang, Yan Ming; Roman, Daniel R.; Smith, Dru A.

2013-03-01

255

Using continuous GPS and absolute gravity to separate vertical land movements and changes in sea-level at tide-gauges in the UK.  

PubMed

Researchers investigating climate change have used historical tide-gauge measurements from all over the world to investigate the changes in sea-level that have occurred over the last century or so. However, such estimates are a combination of any true sea-level variations and any vertical movements of the land at the specific tide-gauge. For a tide- gauge record to be used to determine the climate related component of changes in sea-level, it is therefore necessary to correct for the vertical land movement component of the observed change in sea-level.In 1990, the Institute of Engineering Surveying and Space Geodesy and Proudman Oceanographic Laboratory started developing techniques based on the Global Positioning System (GPS) for measuring vertical land movements (VLM) at tide-gauges in the UK. This paper provides brief details of these early developments and shows how they led to the establishment of continuous GPS (CGPS) stations at a number of tide-gauges. The paper then goes on to discuss the use of absolute gravity (AG), as an independent technique for measuring VLM at tide-gauges. The most recent results, from CGPS time-series dating back to 1997 and AG time-series dating back to 1995/1996, are then used to demonstrate the complementarity of these two techniques and their potential for providing site-specific estimates of VLM at tide-gauges in the UK. PMID:16537148

Teferle, F N; Bingley, R M; Williams, S D P; Baker, T F; Dodson, A H

2006-04-15

256

Nutritional intake and fitness levels of high school cheerleaders  

Microsoft Academic Search

Studies of female sports such as figure skating, dance and gymnastics, especially at the elite levels, have raised serious concerns related to overtraining and disordered eating. However, very little is known about the nutrition and fitness levels of cheerleaders. The present study was designed to identify the fitness levels of female high school cheerleaders, their nutritional intake, and potential eating

Nicole Ferrari

2005-01-01

257

Evaluating Material Flammability in Microgravity and Martian Gravity Compared to the NASA Standard Normal Gravity Test  

NASA Technical Reports Server (NTRS)

Drop tower tests are conducted at Martian gravity to determine the flammability of three materials compared to previous tests in other normal gravity and reduced gravity environments. The comparison is made with consideration of a modified NASA standard test protocol. Material flammability limits in the different gravity and flow environments are tabulated to determine the factor of safety associated with normal gravity flammability screening. Previous testing at microgravity and Lunar gravity indicated that some materials burned to lower oxygen concentrations in low gravity than in normal gravity, although the low g extinction limit criteria are not the same as 1g due to time constraints in drop testing. Similarly, the data presented in this paper for Martian gravity suggest that there is a gravity level below Earth s at which materials burn more readily than on Earth. If proven for more materials, this may indicate the need to include a factor of safety on 1g flammability limits.

Oslon, Sandra. L.; Ferkul, Paul

2012-01-01

258

OGC Sensor Web Enablement: Overview And High Level Architecture  

Microsoft Academic Search

This document provides a high level overview if the Sensor Web Enablement work of the Open Geospatial Consortium. This paper provides a high level architecture and includes descriptions of the OGC sensor interface and encoding standards that have been approved or are soon to be approved.

M. Botts; G. Percivall; C. Reed; J. Davidson

2007-01-01

259

High-level synthesis from VHDL with exact timing constraints  

Microsoft Academic Search

We present a solution to the interface timing problem in high-level synthesis by requiring that the algorithmic specification must completely determine the interface timing on the basis of cycles. We show how this approach has been integrated into the high-level synthesis system CA LLAS.

A. Stoll; Peter Duzy

1992-01-01

260

Logical Traps in High-Level Knowledge and Information Fusion.  

National Technical Information Service (NTIS)

In this paper, we are concerned with high-level information fusion, such as it is envisioned in JDL levels 4 and 5. More precisely, the focus is on decision and reasoning systems that must act in a rational and logical way from several knowledge and high-...

E. Gregoire

2006-01-01

261

Introducing semantic knowledge in high-level fusion  

Microsoft Academic Search

The necessity of taking into account high-level information has recently been reported by the information fusion community. We previously presented an approach for high-level symbolic fusion that relies on the use of the conceptual graphs model. Domain knowledge is a major point of the fusion process. The use of conceptual graphs for knowledge representation eases the process of expressing domain

Claire LAUDY; Jean-Gabriel GANASCIA

2009-01-01

262

Physical Activity Levels in Portuguese High School Physical Education  

ERIC Educational Resources Information Center

The main aim of this study was to evaluate the physical activity (PA) levels of high school Portuguese students during physical education (PE) and investigate the association of PA levels with students' goal orientation and intrinsic motivation. Forty-six students from three high schools participated. Heart rate telemetry and pedometry were used…

Marmeleira, Jose Francisco Filipe; Aldeias, Nuno Micael Carrasqueira; da Graca, Pedro Miguel dos Santos Medeira

2012-01-01

263

Introducing the High-Level-Language Computer Architecture.  

National Technical Information Service (NTIS)

High-level-language (HLL) computer architecture refers to those computer systems which can accept one or more high-level languages (such as FORTRAN, ALGOL, SNOBOL, etc.). The paper classifies the HLL computer architecture into four types (von Neumann arch...

Y. Chu

1973-01-01

264

Predictors of Placement in Lower Level versus Higher Level High School Mathematics  

ERIC Educational Resources Information Center

Educators and researchers have long been interested in determinants of access to honors level and college prep courses in high school. Factors influencing access to upper level mathematics courses are particularly important because of the hierarchical and sequential nature of this subject and because students who finish high school with only lower…

Archbald, Doug; Farley-Ripple, Elizabeth N.

2012-01-01

265

Secondary arm coarsening and microsegregation in superalloy PWA-1480 single crystals: Effect of low gravity  

NASA Technical Reports Server (NTRS)

Single crystal specimens of nickel base superalloy PWA-1480 were directionally solidified on ground and during low gravity (20 sec) and high gravity (90 sec) parabolic maneuver of KC-135 aircraft. Thermal profiles were measured during solidification by two in-situ thermocouples positioned along the sample length. The samples were quenched during either high or low gravity cycles so as to freeze the structures of the mushy zone developing under different gravity levels. Microsegregation was measured by examining the solutal profiles on several transverse cross-sections across primary dendrites along their length in the quenched mushy zone. Effect of gravity level on secondary arm coarsening kinetics and microsegregation have been investigated. The results indicate that there is no appreciable difference in the microsegregation and coarsening kinetics behavior in the specimens grown under high or low gravity. This suggests that short duration changes in gravity/levels (0.02 to 1.7 g) do not influence convection in the interdendritic region. Examination of the role of natural convection, in the melt near the primary dendrite tips, on secondary arm spacings requires low gravity periods longer than presently available on KC-135. Secondary arm coarsening kinetics show a reasonable fit with the predictions from a simple analytical model proposed by Kirkwood for a binary alloy.

Vijayakumar, M.; Tewari, S. N.; Lee, J. E.; Curreri, P. A.

1990-01-01

266

High-level algorithm and architecture transformations for DSP synthesis  

Microsoft Academic Search

This survey paper reviews numerous high-level transformation techniques which can be applied at the algorithm or the architecture\\u000a level to improve the performance of digital signal and image processing architectures and circuits implemented using VLSI\\u000a technology. Successful design of VLSI signal and image processors requires careful selection of algorithms, architectures,\\u000a implementation styles, and synthesis techniques. High-level transformations can play an

Keshab K. Parhi

1995-01-01

267

Sternum Image Retrieval Based on High-level Semantic Information and Low-level Features  

Microsoft Academic Search

In allusion to sternum images, herein we describe a system which supports image retrieval by content. Attention is focused on high-level semantic information representation of medical images. Then a feature fusion algorithm of medical image retrieval using high-level semantic information combining low-level features is presented. A prototype system which supports query by example is designed and implemented on vista operating

Qin Chen; Xiaoying Tai

2008-01-01

268

Lunar Scout Two spacecraft gravity experiment  

Microsoft Academic Search

Measurement of the gravity field of the Moon has a high science priority because of its implications for the internal structure and thermal history of the Moon, and it has a high priority for future exploration activities because of the influence of lunar gravity on spacecraft navigation and orbit maintenance. The current state of knowledge in the lunar gravity field

Andrew F. Cheng

1993-01-01

269

Simulated variability of the high-latitude thermosphere induced by small-scale gravity waves during a sudden stratospheric warming  

NASA Astrophysics Data System (ADS)

We present the results of the first investigation of the influence of small-scale gravity waves (GWs) originating in the lower atmosphere on the variability of the high-latitude thermosphere during a sudden stratospheric warming (SSW). We use a general circulation model that incorporates the spectral GW parameterization of Yi?it et al. (2008). During the warming, the GW penetration into the thermosphere and resulting momentum deposition rates increase by up to a factor of 3-6 in the high-latitude thermosphere. The associated temporal variability of GW dynamical effects at ~250 km are enhanced by up to a factor of ~10, exhibiting complex geographical variations. The peak magnitude of the GW drag temporal variability locally exceeds the mean GW drag by more than a factor of 2. The small-scale thermospheric wind variability is larger when GW propagation into the thermosphere is allowed compared to the case when thermospheric GW effects are absent. These results suggest that GW-induced variations during SSWs constitute a significant source of high-latitude thermospheric variability.

Yi?it, Erdal; Medvedev, Alexander S.; England, Scott L.; Immel, Thomas J.

2014-01-01

270

Cosmological Applications of Loop Quantum Gravity  

Microsoft Academic Search

After a brief introduction to classical and quantum gravity we discuss applications of loop quantum gravity in the cosmological realm. This includes the basic formalism and recent results of loop quantum cosmology, and a computation of modified dispersion relations for quantum gravity phenomenology. The presentation is held at a level which does not require much background knowledge in general relativity

Martin Bojowald; Hugo A. Morales-Tecotl

2004-01-01

271

[Biology of size and gravity].  

PubMed

Gravity is a force that acts on mass. Biological effects of gravity and their magnitude depend on scale of mass and difference in density. One significant contribution of space biology is confirmation of direct action of gravity even at the cellular level. Since cell is the elementary unit of life, existence of primary effects of gravity on cells leads to establish the firm basis of gravitational biology. However, gravity is not limited to produce its biological effects on molecules and their reaction networks that compose living cells. Biological system has hierarchical structure with layers of organism, group, and ecological system, which emerge from the system one layer down. Influence of gravity is higher at larger mass. In addition to this, actions of gravity in each layer are caused by process and mechanism that is subjected and different in each layer of the hierarchy. Because of this feature, summing up gravitational action on cells does not explain gravity for biological system at upper layers. Gravity at ecological system or organismal level can not reduced to cellular mechanism. Size of cells and organisms is one of fundamental characters of them and a determinant in their design of form and function. Size closely relates to other physical quantities, such as mass, volume, and surface area. Gravity produces weight of mass. Organisms are required to equip components to support weight and to resist against force that arise at movement of body or a part of it. Volume and surface area associate with mass and heat transport process at body. Gravity dominates those processes by inducing natural convection around organisms. This review covers various elements and process, with which gravity make influence on living systems, chosen on the basis of biology of size. Cells and biochemical networks are under the control of organism to integrate a consolidated form. How cells adjust metabolic rate to meet to the size of the composed organism, whether is gravity responsible for this feature, are subject we discuss in this article. Three major topics in gravitational and space biology are; how living systems have been adapted to terrestrial gravity and evolved, how living systems respond to exotic gravitational environment, and whether living systems could respond and adapt to microgravity. Biology of size can contribute to find a way to answer these question, and answer why gravity is important in biology, at explaining why gravity has been a dominant factor through the evolutional history on the earth. PMID:15173628

Yamashita, Masamichi; Baba, Shoji A

2004-03-01

272

Gravity field of the Western Weddell Sea: Comparison of airborne gravity and Geosat derived gravity  

NASA Technical Reports Server (NTRS)

Marine gravity surveying in polar regions was typically difficult and costly, requiring expensive long range research vessels and ice-breakers. Satellite altimetry can recover the gravity field in these regions where it is feasible to survey with a surface vessel. Unfortunately, the data collected by the first global altimetry mission, Seasat, was collected only during the austral winter, producing a very poor quality gravitational filed for the southern oceans, particularly in the circum-Antarctic regions. The advent of high quality airborne gravity (Brozena, 1984; Brozena and Peters, 1988; Bell, 1988) and the availability of satellite altimetry data during the austral summer (Sandwell and McAdoo, 1988) has allowed the recovery of a free air gravity field for most of the Weddell Sea. The derivation of the gravity field from both aircraft and satellite measurements are briefly reviewed, before presenting along track comparisons and shaded relief maps of the Weddell Sea gravity field based on these two data sets.

Bell, R. E.; Brozena, J. M.; Haxby, W. F.; Labrecque, J. L.

1989-01-01

273

Plasma hormone levels in human subject during stress loads in microgravity and at readaptation to Earth's gravity.  

PubMed

In great part of the investigations of endocrine system functions in astronauts during space flights the plasma levels of hormones and metabolites were determined only in resting conditions, usually from one blood sample collection. Such levels reflected the psychical and physical state and new hormonal homeostasis of organism at the time of blood collection, however, the functional capacity of neuroendocrine system to respond to various stress stimuli during space flight remained unknown. The aim of present investigations was to study dynamic changes of hormone levels during the stress and metabolic loads (insulin induced hypoglycemia, physical exercise and oral glucose tolerance test) at the exposure of human subject to microgravity on the space station MIR. The responses of sympatico-adrenomedullary system to these stress and workloads were presented by Kvetnansky et al. PMID:12650202

Macho, L; Koska, J; Ksinantova, L; Vigas, M; Noskov, V B; Grigoriev, A I; Kvetnansky, R

2001-07-01

274

Mars - Crustal structure inferred from Bouguer gravity anomalies.  

NASA Technical Reports Server (NTRS)

Bouguer gravity has been computed for the equatorial region of Mars by differencing free air gravity and the gravity predicted from topographic variations. The free air gravity was generated from an eighth-order set of spherical harmonic coefficients. The gravity from topographic variations was generated by integrating a two-dimensional Green's function over each contour level. The Bouguer gravity indicates crustal inhomogeneities on Mars that are postulated to be variations in crustal thickness. The Tharsis ridge is a region of thick continental type crust. The gravity data, structural patterns, topography, and surface geology of this region lead to the interpretation of the Tharsis topographic high as a broad crustal upwarp possibly associated with local formation of lower-density crustal material and subsequent rise of a thicker crust. The Amazonis region is one of several basins of relatively thin crust, analogous to terrestrial ocean basins. The Libya and Hellas basins, which are probable impact features, are also underlain by thin crust and are possible regions of mantle upwelling.

Phillips, R. J.; Saunders, R. S.; Conel, J. E.

1973-01-01

275

GRAIL Gravity Field Determination Using the Celestial Mechanics Approach  

NASA Astrophysics Data System (ADS)

To determine the gravity field of the Moon, the NASA mission GRAIL (Gravity Recovery and Interior Laboratory) inherits its concept from the GRACE (Gravity Recovery and Climate Experiment) mission. The use of inter-satellite Ka-band range-rate (KBRR) observations enables data acquisition even when the spacecraft are not tracked from the Earth. The data allows for a highly accurate estimation of the lunar gravity field on both sides of the Moon, which is crucial to improve the understanding of its internal structure and thermal evolution. In this presentation we discuss GRAIL-based lunar gravity fields generated with the Celestial Mechanics Approach. KBRR observations and position data (GNI1B products) are used to solve for the lunar gravity field parameters in a generalized orbit determination problem. Apart from normalized spherical harmonic coefficients up to degrees n ? 200, also arc- and satellite-specific parameters, like initial state vectors and pseudo-stochastic pulses, are set up as common parameters for all measurement types. The latter shall compensate for imperfect models of non-gravitational accelerations, e.g., caused by solar radiation pressure. In addition, especially for the data of the primary mission phase, it is essential to estimate time bias parameters for the KBRR observations. We compare our results from the nominal and from the extended mission phase with the official Level 2 gravity field models first released in October 2013. Our results demonstrate that the lunar gravity field can be recovered with a high quality by adapting the Celestial Mechanics Approach, even when using pre-GRAIL or pre-SELENE gravity field models as a priori fields and when replacing sophisticated models of non-gravitational accelerations by appropriately spaced and constrained pseudo-stochastic pulses.

Arnold, Daniel; Jäggi, Adrian; Bertone, Stefano; Beutler, Gerhard; Meyer, Ulrich; Mervart, Leos; Bock, Heike

2014-05-01

276

National high-level waste systems analysis report  

SciTech Connect

This report documents the assessment of budgetary impacts, constraints, and repository availability on the storage and treatment of high-level waste and on both existing and pending negotiated milestones. The impacts of the availabilities of various treatment systems on schedule and throughput at four Department of Energy sites are compared to repository readiness in order to determine the prudent application of resources. The information modeled for each of these sites is integrated with a single national model. The report suggests a high-level-waste model that offers a national perspective on all high-level waste treatment and storage systems managed by the Department of Energy.

Kristofferson, K.; Oholleran, T.P.; Powell, R.H.

1995-09-01

277

Reference commercial high-level waste glass and canister definition.  

SciTech Connect

This report presents technical data and performance characteristics of a high-level waste glass and canister intended for use in the design of a complete waste encapsulation package suitable for disposal in a geologic repository. The borosilicate glass contained in the stainless steel canister represents the probable type of high-level waste product that will be produced in a commercial nuclear-fuel reprocessing plant. Development history is summarized for high-level liquid waste compositions, waste glass composition and characteristics, and canister design. The decay histories of the fission products and actinides (plus daughters) calculated by the ORIGEN-II code are presented.

Slate, S.C.; Ross, W.A.; Partain, W.L.

1981-09-01

278

Crustal architecture of the Faroe-Shetland Margin: insights from a newly merged high resolution gravity and magnetic dataset  

NASA Astrophysics Data System (ADS)

The Faroe-Shetland region is geologically complex; it has undergone several phases of extension and rifting since the middle Palaeozoic (Ritchie et al., 2011; Coward et al., 2003), culminating in the Eocene with continental breakup between Northwest Europe and Greenland (Gernigon et al., 2012). Final breakup may have been facilitated by the presence of the Iceland Plume and was accompanied by the emplacement of voluminous basaltic rocks, attributed to the North Atlantic Igneous Province (White and McKenzie, 1989). It is difficult to image beneath the thick Paleogene basalts in the region using conventional seismic methods, because the high impedance contrast between the sediments and shallow basalts causes strong reflections. These mask deeper and weaker reflections and cause prominent inter-bed multiples (White et al., 1999). Consequently, determining the location and shape of basins and basement highs, and elucidating the timing and manner of their formation, remains a major cause of uncertainty in the appraisal of the hydrocarbon potential of the region. Gravity and magnetic data record variations in the density and susceptibility of the entire crust. Consequently, the thick basalt piles that are shallow in the section do not hinder the ability to detect deeper features. Instead, the principal challenge is distinguishing superposed bodies, with different densities and susceptibilities, from the combined gravity and magnetic anomalies. In this study, seismic data and horizons from the shallow section are used in combination with gravity and magnetic data to produce map view interpretations, and 2D and 3D models of the crust in the Faroe-Shetland region. These models help distinguish important variations in timing of rifting in different basins, and reveal the crustal architecture of the Faroe-Shetland Basin from the seabed to the Moho. We present a new structural and kinematic interpretation of the geology of the region, and propose an asymmetric simple shear model for the Faroe-Shetland segment of the UK Atlantic Margin. The authors would like to acknowledge the management at ARKeX and PGS for giving permission to present this work. Coward, M.., Dewey, J.F., Hempton, M., and Holroyd, J., 2003, Tectonic evolution, in Evans, D., Graham, C.G., Armour, A., and P, B. eds., Millenium Atlas: petroleum geology of the central and northern North Sea, Geological Society of London. Gernigon, L., Gaina, C., Olesen, O., Ball, P.J., Péron-Pinvidic, G., and Yamasaki, T., 2012, The Norway Basin revisited: From continental breakup to spreading ridge extinction: Marine and Petroleum Geology, v. 35, no. 1, p. 1-19. Ritchie, J.D., Ziska, H., Johnson, H., and Evans, D., 2011, Structure, in Ritchie, J.D., Ziska, H., Johnson, H., and Evans, D. eds., Geology of the Faroe-Shetland Basin and adjacent areas, British Geological Survey, Faroeses Earth and Energy Directorate, p. 9-70. White, R.S., Fruehn, J., Richardson, K.R., Cullen, E., Kirk, W., and Latkiewicz, C., 1999, Faeroes Large Aperture Research Experiment ( FLARE ): imaging through basalt, in Fleet, A.J. and Boldy, S.A.R. eds., Petroleum Geology of Northwest Europe and Global Perspectives: Proceedings of the 5th Conference, Geological Society of London, p. 1243-1252. White, R., and McKenzie, D., 1989, Magmatism at Rift Zones: The Generation of Volcanic Continental Margins: Journal of Geophysical Research, v. 94, no. B6, p. 7685-7729.

Rippington, Stephen; Mazur, Stan; Anderson, Chris

2014-05-01

279

The ATLAS high level trigger region of interest builder.;  

SciTech Connect

This article describes the design, testing and production of the ATLAS Region of Interest Builder (RoIB). This device acts as an interface between the Level 1 trigger and the high level trigger (HLT) farm for the ATLAS LHC detector. It distributes all of the Level 1 data for a subset of events to a small number of (16 or less) individual commodity processors. These processors in turn provide this information to the HLT. This allows the HLT to use the Level 1 information to narrow data requests to areas of the detector where Level 1 has identified interesting objects.

Blair, R.; Dawson, J.; Drake, G.; Haberichter, W.; Schlereth, J.; Zhang, J.; Ermoline, Y.; Pope, B.; Aboline, M.; High Energy Physics; Michigan State Univ.

2008-04-01

280

The High Precision Calculation of Anomalous Vertical Gravity Gradients die Berechnung von Anomalen Vertikalen Schweregradienten Hoher Praezision.  

National Technical Information Service (NTIS)

Accurate methods for the calculation of anomalous vertical gravity gradients based on the Molodensky theory are presented. The general solution of the mathematical problem leads to a singular inhomogeneous second order integral equation that can be solved...

G. Hein

1977-01-01

281

A high-quality global gravity field model from CHAMP GPS tracking data and accelerometry (EIGEN1S)  

Microsoft Academic Search

Using three months of GPS satellite-to-satellite tracking and accelerometer data of the CHAMP satellite mission, a new long-wavelength global gravity field model, called EIGEN-1S, has been prepared in a joint German-French effort. The solution is derived solely from analysis of satellite orbit perturbations, i.e. independent of oceanic and continental surface gravity data. EIGEN-1S results in a geoid with an approximation

Christoph Reigber; Georges Balmino; Peter Schwintzer; Richard Biancale; Albert Bode; Jean-Michel Lemoine; Rolf König; Sylvain Loyer; Hans Neumayer; Jean-Charles Marty; Franz Barthelmes; Felix Perosanz; Shen Yuan Zhu

2002-01-01

282

Venus - Multiple Views of High-level Clouds  

NASA Technical Reports Server (NTRS)

This series of pictures shows four views of the planet Venus obtained by Galileo's Solid State Imaging System at ranges of 1.4 to 2 million miles as the spacecraft receded from Venus. The pictures in the top row were taken about 4 and 5 days after closest approach; those in the bottom row were taken about 6 days out, 2 hours apart. In these violet-light images, north is at the top and the evening terminator to the left. The cloud features high in the planet's atmosphere rotate from right to left, from the limb through the noon meridian toward the terminator, traveling all the way around the planet once every four days. The motion can be seen by comparing the last two pictures, taken two hours apart. The other views show entirely different faces of Venus. These photographs are part of the 'Venus global circulation' sequence planned by the imaging team. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity-assist flybys at Venus and Earth.

1990-01-01

283

Defying gravity using Jenga™ blocks  

NASA Astrophysics Data System (ADS)

This paper describes how Jenga™ blocks can be used to demonstrate the physics of an overhanging tower that appears to defy gravity. We also propose ideas for how this demonstration can be adapted for the A-level physics curriculum.

Tan, Yin-Soo; Yap, Kueh-Chin

2007-11-01

284

Structure and Effects of Gravity Waves in the Thermosphere From Lower Atmospheric Sources  

NASA Astrophysics Data System (ADS)

Gravity waves from lower atmospheric sources such as deep convection can propagate into the thermosphere if they avoid evanescence and critical level filtering in the lower atmosphere. Some of these gravity waves have large vertical wavelengths and high frequencies, allowing them to propagate to high altitudes within the thermosphere before dissipating. Dissipation by molecular viscosity and thermal diffusivity is described via implementation of a new anelastic dispersion relation. Solar cycle effects are important because gravity wave dissipation depends on the inverse density which increases more slowly as the background temperature increases. Additionally, gravity wave vertical wavelengths increase as the background temperature increases. Together, these effects increase the gravity wave penetration altitude and alter the gravity wave structure within the thermosphere. At extreme solar minimum whereby the thermosphere is the coolest, gravity waves from lower atmospheric sources may penetrate to altitudes of ~ 200 km, while during active solar conditions, these gravity waves may penetrate to altitudes of ~ 250-300 km instead. Although not well understood at present, the dissipation of these gravity waves and subsequent forcing of the thermosphere may lead to seeding of plasma instabilities and spread-F bubbles commonly observed in the thermosphere at these altitudes and scales.

Vadas, S. L.

2005-12-01

285

Highly efficient and flexible electrospun carbon-silica nanofibrous membrane for ultrafast gravity-driven oil-water separation.  

PubMed

A novel free-standing and flexible electrospun carbon-silica composite nanofibrous membrane is newly introduced. The characterization results suggest that the electrospun composite nanofibers are constructed by carbon chains interpenetrated through a linear network of 3-dimensional SiO2. Thermogravimetric analysis indicates that the presence of insulating silica further improve the thermal resistance of the membrane. Additionally, the mechanical strength test shows that the membrane's toughness and flexibility can be enhanced if the concentration of SiO2 is maintained below 2.7 wt %. Thermal and chemical stability test show that the membrane's wettability properties can be sustained at an elevated temperature up to 300 °C and no discernible change in wettability was observed under highly acidic and basic conditions. After surface-coating with silicone oil for 30 mins, the composite membrane exhibits ultra-hydrophobic and superoleophilic properties with water and oil contact angles being 144.2 ± 1.2° and 0°, respectively. The enhanced flexibility and selective wetting property enables the membrane to serve as an effective substrate for separating free oil from water. Lab-scale oil-water separation test indicates that the membrane possesses excellent oil-water separation efficiency. In addition, its inherent property of high porosity allows oil-water separation to be performed in a gravity-driven process with high-flux. We anticipate that this study will open up a new avenue for fabrication of free-standing carbonaceous composite membrane with tunable flexibility for energy efficient and high-throughput production of clean water. PMID:24867399

Tai, Ming Hang; Gao, Peng; Tan, Benny Yong Liang; Sun, Darren D; Leckie, James O

2014-06-25

286

Survey of the Characteristics of Very High Level Languages.  

National Technical Information Service (NTIS)

Although there is no consensus on the characteristics of very high level languages (VHLLs), ample evidence exists that users of such languages have several expectations. As a result of an extensive survey of the literature and communications with research...

R. S. Loffman

1986-01-01

287

Impact Testing of Simulated High-Level Waste Glass Canisters.  

National Technical Information Service (NTIS)

Three Savannah River Laboratory reference high-level waste canisters were subjected to impact tests at the Pacific Northwest Laboratory in Richland, Washington, in June 1983. The purpose of the test was to determine the integrity of the canister, nozzle, ...

M. E. Peterson J. M. Alzheimer S. C. Slate

1985-01-01

288

Low Vitamin D Levels Linked to High Blood Pressure  

MedlinePLUS

... on this page, please enable JavaScript. Low Vitamin D Levels Linked to High Blood Pressure Researchers recommend more studies to see if vitamin D supplements can lower pressure (*this news item will ...

289

High Performance Execution Engines for Instruction Level Parallel Processors.  

National Technical Information Service (NTIS)

The authors present high performance execution units suitable to instruction level pipelined parallel processors. First, the authors investigate arithmetic logic unit interlocks for fixed point instruction processing. The authors show that interlocked fix...

J. E. Phillips

1997-01-01

290

Neptunium estimation in dissolver and high-level-waste solutions  

SciTech Connect

This papers deals with the optimization of the experimental conditions for the estimation of {sup 237}Np in spent-fuel dissolver/high-level waste solutions using thenoyltrifluoroacetone as the extractant. (authors)

Pathak, P.N.; Prabhu, D.R.; Kanekar, A.S.; Manchanda, V.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085 (India)

2008-07-01

291

High Level Implementation Plan, 2000. Trust Management Improvement Project (Revised).  

National Technical Information Service (NTIS)

In July 1998, the Department of the Interior issued the first High Level Implementation Plan (HLIP) for Indian Trust Management Improvement. That plan represented the first step in implementing the strategic plan required by Section 303 of the American In...

2000-01-01

292

Test Procedures for High Level Architecture Interface Specification.  

National Technical Information Service (NTIS)

This document contains test procedures for the High Level Architecture (HLA) Interface Specification, v1. 3. Section I discusses the terminology used, the organization of the procedures, and how the procedures are defined.

M. L. Loper

1998-01-01

293

High-Level Synthesis for FPGAs: From Prototyping to Deployment  

Microsoft Academic Search

Escalating system-on-chip design complexity is pushing the design community to raise the level of abstraction beyond register transfer level. Despite the unsuccessful adoptions of early generations of commercial high-level synthesis (HLS) systems, we believe that the tipping point for transitioning to HLS methodology is happening now, especially for field-programmable gate array (FPGA) designs. The latest generation of HLS tools has

Jason Cong; Bin Liu; Stephen Neuendorffer; Juanjo Noguera; Kees A. Vissers; Zhiru Zhang

2011-01-01

294

Measures of effectiveness for high-level fusion  

Microsoft Academic Search

Current advances in technology, sensor collection, data storage, and data distribution have afforded more complex, distributed, and operational information fusion systems (IFSs). IFSs notionally consist of low-level (data collection, registration, and association in time and space) and high-level fusion (user coordination, situational awareness, and mission control). Low-level IFSs typically rely on standard metrics for evaluation such as timeliness, accuracy, and

Erik Blasch; Pierre Valin; Eloi Bosse

2010-01-01

295

Some experiences with experimental high level fusion systems  

Microsoft Academic Search

A very short overview is given on experience gained in the area of high level information fusion (JDL level 2 and 3) since 1988. The main characteristics of the referenced projects and experimental systems for the support of intelligence officers in land battle missions will be outlined. The different approaches to analyse and model military intelligence processing and the development

J. Biermann

2007-01-01

296

Hierarchical High Level Information Fusion (H2LIFT).  

National Technical Information Service (NTIS)

The primary objective of this effort was the progression of Level 2/3 fusion of informational content to obtain an advanced multi-intelligent system for hierarchical high-level decision making processes. The goal was to develop an information integration ...

A. Crassidis A. Stotz J. Crassidis M. Sudit R. Nagi

2008-01-01

297

The case for high-level parallel programming in ZPL  

Microsoft Academic Search

Message passing programs are efficient, but fall short on convenience and portability. ZPL is a high level language that offers competitive performance and portability, as well as programming conveniences lacking in low level approaches. ZPL runs on a variety of parallel and sequential computers. We describe the problems with message passing and describe how ZPL simplifies the task of programming

BRADFORD L. CHAMBERLAIN; Sung-Eun Choi; E CHRISTOPHER LEWIS; LAWRENCE SNYDER; W. D. Weathersby; C. Lin

1998-01-01

298

High-Level Waste System Process Interface Description  

SciTech Connect

The High-Level Waste System is a set of six different processes interconnected by pipelines. These processes function as one large treatment plant that receives, stores, and treats high-level wastes from various generators at SRS and converts them into forms suitable for final disposal. The three major forms are borosilicate glass, which will be eventually disposed of in a Federal Repository, Saltstone to be buried on site, and treated water effluent that is released to the environment.

d'Entremont, P.D.

1999-01-14

299

Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs  

SciTech Connect

Free-air gravity highs over forearcs represent a large fraction of the power in the Earth`s anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local earthquakes, recorded by a seismic network in the eastern Aleutians, are inverted for three-dimensional velocity structure between the volcanic arc and the downgoing plate. A three-dimensional ray tracing scheme is used to invert the 7974 P and 6764 S arrivals for seismic velocities and hypocenters of 635 events. One-dimensional inversions show that station P residuals are systematically 0.25 - 0.5 s positive at stations 0-30 km north of the Aleutian volcanic arc, indicating slow material, while residuals at stations 10-30 km south of the arc are 0.1-0.25 s negative. Both features are explained in three-dimensional inversions by velocity variations at depths less than 25-35 km. Tests using a one-dimensional or a two-dimensional slab starting model show that below 100 km depth, velocities are poorly determined and trade off almost completely with hypocenters for earthquakes at these depths. The locations of forearc velocity highs, in the crust of the upper plate, correspond to the location of the gravity high between the trench and volcanic arc. Free-air anomalies, calculated from the three-dimensional velocity inversion result, match observed gravity for a linear density-velocity relationship between 0.1 and 0.3 (Mg m{sup {minus}3})/(km s{sup {minus}1}), when a 50-km-thick slab is included with a density of 0.055{+-}0.005 Mg m{sup {minus}3}. Values outside these ranges do not match the observed gravity. The slab alone contributes one third to one half of the total 75-150 mGal amplitude of the gravity high but predicts a high that is much broader than is observed.

Abers, G.A. [Columbia Univ., Palisades, NY (United States)] [Columbia Univ., Palisades, NY (United States)

1994-03-10

300

Venus Gravity Handbook  

NASA Technical Reports Server (NTRS)

This report documents the Venus gravity methods and results to date (model MGNP90LSAAP). It is called a handbook in that it contains many useful plots (such as geometry and orbit behavior) that are useful in evaluating the tracking data. We discuss the models that are used in processing the Doppler data and the estimation method for determining the gravity field. With Pioneer Venus Orbiter and Magellan tracking data, the Venus gravity field was determined complete to degree and order 90 with the use of the JPL Cray T3D Supercomputer. The gravity field shows unprecedented high correlation with topography and resolution of features to the 2OOkm resolution. In the procedure for solving the gravity field, other information is gained as well, and, for example, we discuss results for the Venus ephemeris, Love number, pole orientation of Venus, and atmospheric densities. Of significance is the Love number solution which indicates a liquid core for Venus. The ephemeris of Venus is determined to an accuracy of 0.02 mm/s (tens of meters in position), and the rotation period to 243.0194 +/- 0.0002 days.

Konopliv, Alexander S.; Sjogren, William L.

1996-01-01

301

Solidifying Cast Iron in Low Gravity  

NASA Technical Reports Server (NTRS)

Report describes study of solidification of cast iron in low and normal gravity. Because flotation, sedimentation, and convection suppressed, alloys that solidify at nearly zero gravity have unusual and potentially useful characteristics. Study conducted in airplane that repeatedly flew along parabolic trajectories. Appears iron/carbon alloys made at low gravity have greater carbon content (as high as 5 to 10 percent) than those made of Earth gravity because carbon particles do not float to top of melt.

Hendrix, J. C.; Curreri, P. A.; Stefanescu, D. M.

1986-01-01

302

High-Level Synthesis of Software Function Calls  

NASA Astrophysics Data System (ADS)

This letter presents a novel framework in high-level synthesis where hardware modules synthesized from functions in a given ANSI-C program can call the other software functions in the program. This enables high-level synthesis from C programs that contains calls to hard-to-synthesize functions, such as dynamic memory management, I/O request, or very large and complex functions. A single-thread implementation scheme is shown, whose correctness has been verified through register transfer level simulation.

Nishimura, Masanari; Ishiura, Nagisa; Ishimori, Yoshiyuki; Kanbara, Hiroyuki; Tomiyama, Hiroyuki

303

Gravity changes, soil moisture and data assimilation  

NASA Astrophysics Data System (ADS)

Remote sensing holds promise for near-surface soil moisture and snow mapping, but current techniques do not directly resolve the deeper soil moisture or groundwater. The benefits that would arise from improved monitoring of variations in terrestrial water storage are numerous. The year 2002 saw the launch of NASA's Gravity Recovery And Climate Experiment (GRACE) satellites, which are mapping the Earth's gravity field at such a high level of precision that we expect to be able to infer changes in terrestrial water storage (soil moisture, groundwater, snow, ice, lake, river and vegetation). The project described here has three distinct yet inter-linked components that all leverage off the same ground-based monitoring and land surface modelling framework. These components are: (i) field validation of a relationship between soil moisture and changes in the Earth's gravity field, from ground- and satellite-based measurements of changes in gravity; (ii) development of a modelling framework for the assimilation of gravity data to constrain land surface model predictions of soil moisture content (such a framework enables the downscaling and disaggregation of low spatial (500 km) and temporal (monthly) resolution measurements of gravity change to finer spatial and temporal resolutions); and (iii) further refining the downscaling and disaggregation of space-borne gravity measurements by making use of other remotely sensed information, such as the higher spatial (25 km) and temporal (daily) resolution remotely sensed near-surface soil moisture measurements from the Advanced Microwave Scanning Radiometer (AMSR) instruments on Aqua and ADEOS II. The important field work required by this project will be in the Murrumbidgee Catchment, Australia, where an extensive soil moisture monitoring program by the University of Melbourne is already in place. We will further enhance the current monitoring network by the addition of groundwater wells and additional soil moisture sites. Ground-based gravity measurements will also be made on a monthly basis at each monitoring site. There will be two levels of modelling and monitoring; regional across the entire Murrumbidgee Catchment (100,000 km2), and local across a small sub-catchment (150 km2).

Walker, J.; Grayson, R.; Rodell, M.; Ellet, K.

2003-04-01

304

Selection of artificial gravity by animals during suborbital rocket flights  

NASA Technical Reports Server (NTRS)

White rats selected preferred artificial gravity levels by locomotion in centrifuges consisting of two runways mounted in the nose of sounding rockets. Roll rate of the Aerobee 150A rocket was designed to produce an angular velocity of 45 rpm during 5 min of free-fall, providing a gravity range from 0.3 to 1.5 G depending on a subject's runway position. One animal was released at the high and one at the low gravity position in each flight. Animal positions were continuously recorded. Locomotion patterns during these flights were similar. All four animals explored the entire available G-range. One rat settled at 0.4 G after 2 min; the others crossed the 1-G location in progressively narrower excursions and were near earth gravity at the end of the test period. Tentatively, the data suggest that normal earth-reared rats select earth gravity when available magnitudes include values above and below 1 G. Modification of gravity preference by prolonged exposure to higher or lower levels remains a possibility.

Lange, K. O.; Belleville, R. E.; Clark, F. C.

1975-01-01

305

Belle-II High Level Trigger at SuperKEKB  

NASA Astrophysics Data System (ADS)

A next generation B-factory experiment, Belle II, is now being constructed at KEK in Japan. The upgraded accelerator SuperKEKB is designed to have the maximum luminosity of 8 × 1035 cm-2s-1 that is a factor 40 higher than the current world record. As a consequence, the Belle II detector yields a data stream of the event size ~1 MB at a Level 1 rate of 30 kHz. The Belle II High Level Trigger (HLT) is designed to reduce the Level 1 rate to 1/5 by performing the real time full event reconstruction and by applying the physics level event selection as the software trigger. In this paper, the development of the high level trigger system for Belle II and its performance is discussed.

Lee, S.; Itoh, R.; Higuchi, T.; Nakao, M.; Suzuki, S. Y.; Won, E.

2012-12-01

306

An overview of very high level software design methods  

NASA Technical Reports Server (NTRS)

Very High Level design methods emphasize automatic transfer of requirements to formal design specifications, and/or may concentrate on automatic transformation of formal design specifications that include some semantic information of the system into machine executable form. Very high level design methods range from general domain independent methods to approaches implementable for specific applications or domains. Applying AI techniques, abstract programming methods, domain heuristics, software engineering tools, library-based programming and other methods different approaches for higher level software design are being developed. Though one finds that a given approach does not always fall exactly in any specific class, this paper provides a classification for very high level design methods including examples for each class. These methods are analyzed and compared based on their basic approaches, strengths and feasibility for future expansion toward automatic development of software systems.

Asdjodi, Maryam; Hooper, James W.

1988-01-01

307

High Power MPD Nuclear Electric Propulsion (NEP) for Artificial Gravity HOPE Missions to Callisto  

NASA Astrophysics Data System (ADS)

The following paper documents the results of a one-year multi-center NASA study on the prospect of sending humans to Jupiter's moon, Callisto, using an all Nuclear Electric Propulsion (NEP) space transportation system architecture with magnetoplasmadynamic (MPD) thrusters. The fission reactor system utilizes high temperature uranium dioxide (UO2) in tungsten (W) metal matrix ``cermet'' fuel and electricity is generated using advanced dynamic Brayton power conversion technology. The mission timeframe assumes on-going human Moon and Mars missions and existing space infrastructure to support launch of cargo and crewed spacecraft to Jupiter in 2041 and 2045, respectively.

McGuire, Melissa L.; Borowski, Stanley K.; Mason, Lee M.; Gilland, James

2003-01-01

308

Crystallization of Mg–Al and Al-based metallic liquids under ultra-high gravity  

Microsoft Academic Search

We present results from high-temperature centrifugal processing, which is a new method to detect the sequence of crystallization and to physically isolate eutectic compositions in multi-component alloys. Alloys of composition Mg50Al30Y6Li7Cu7, Mg50Al30Y6Li7Cu7, and Al52.6Cu13.4Ge28Si6 were processed for 2 h in a centrifuge above their melting point at an inertial acceleration of 60,000 g (g=gravitational acceleration) and then slowly cooled to

Jörg F Löffler; William L Johnson

2002-01-01

309

High Power MPD Nuclear Electric Propulsion (NEP) for Artificial Gravity HOPE Missions to Callisto  

NASA Technical Reports Server (NTRS)

This documents the results of a one-year multi-center NASA study on the prospect of sending humans to Jupiter's moon, Callisto, using an all Nuclear Electric Propulsion (NEP) space transportation system architecture with magnetoplasmadynamic (MPD) thrusters. The fission reactor system utilizes high temperature uranium dioxide (UO2) in tungsten (W) metal matrix cermet fuel and electricity is generated using advanced dynamic Brayton power conversion technology. The mission timeframe assumes on-going human Moon and Mars missions and existing space infrastructure to support launch of cargo and crewed spacecraft to Jupiter in 2041 and 2045, respectively.

McGuire, Melissa L.; Borowski, Stanley K.; Mason, Lee M.; Gilland, James

2003-01-01

310

A Testing Instrument for High School Arabic, Level III.  

ERIC Educational Resources Information Center

The Arabic language examination was designed for Jewish immigrants from Syria wishing to satisfy New York State language requirements for high school graduation by indicating their proficiency in Arabic. The test is essentially a translation of a state test of Hebrew, and is intended to test Arabic at the third-year high school level. The…

Wolowelsky, Joel B.

311

The effects of high presentation levels on consonant feature transmission.  

PubMed

The effect of high speech presentation levels on consonant recognition and feature transmission was assessed in eight participants with normal hearing. Consonant recognition in noise (0 dB signal-to-noise ratio) was measured at five overall speech levels ranging from 65 to 100 dB SPL. Consistent with the work of others, overall percent correct performance decreased as the presentation level of speech increased [e.g., G. A. Studebaker, R. L. Sherbecoe, D. M. McDaniel, and C. A. Gwaltney, J. Acoust. Soc. Am. 105(4), 2431-2444 (1999)]. Confusion matrices were analyzed in terms of relative percent information transmitted at each speech presentation level, as a function of feature. Six feature sets (voicing, place, nasality, duration, frication, and sonorance) were analyzed. Results showed the feature duration (long consonant duration fricatives) to be most affected by increases in level, while the voicing feature was relatively unaffected by increases in level. In addition, alveolar consonants were substantially affected by level, while palatal consonants were not. While the underlying mechanisms responsible for decreases in performance with level increases are unclear, an analysis of common error patterns at high levels suggests that saturation of the neural response and/or a loss of neural synchrony may play a role. PMID:16240830

Hornsby, Benjamin W Y; Trine, Timothy D; Ohde, Ralph N

2005-09-01

312

Effect of water immersion on cardiopulmonary physiology at high gravity (+Gz)  

NASA Technical Reports Server (NTRS)

The cardiopulmonary responses of eight male subject between 21-31 years exposed to 1, 2, and 3 Gz during immersion at 35 + or - 0.5 C to heart level and during control dry rides are studied. Ventilation, O2 consumption, the end-tidal pressure of CO2, heart frequency, cardiac output, functional residual capacity, and the arterial pressure of CO2 were measured. It is observed that as Gz increases ventilation, heart frequency, and O2 consumption increase, and the end-tidal and arterial pressures of CO2 decrease during dry rides, but are not altered during immersion. It is detected that the functional residual capacity is lower during immersion and decreases in both the dry and immersed state as Gz increases, and cardiac output decreases as Gz increases in dry rides. It is noted that changes produced by acceleration in a Gz direction are due to the effect on the systemic circulation rather than to the effect on the lungs.

Arieli, R.; Boutellier, U.; Farhi, L. E.

1986-01-01

313

Europe's Preparation For GOCE Gravity Field Recovery  

NASA Astrophysics Data System (ADS)

The European Space Agency ESA is preparing for its first dedicated gravity field mission GOCE (Gravity Field and Steady-state Ocean Circulation Explorer) with a proposed launch in fall 2005. The mission's goal is the mapping of the Earth's static gravity field with very high resolution and utmost accuracy on a global scale. GOCE is a drag-free mission, flown in a circular and sun-synchronous orbit at an altitude between 240 and 250 km. Each of the two operational phases will last for 6 months. GOCE is based on a sensor fusion concept combining high-low satellite-to-satellite tracking (SST) and satellite gravity gradiometry (SGG). The transformation of the GOCE sensor data into a scientific product of utmost quality and reliability requires a well-coordinated effort of experts in satellite geodesy, applied mathematics and computer science. Several research groups in Europe do have this expertise and decided to form the "European GOCE Gravity Consortium (EGG-C)". The EGG-C activities are subdivided into tasks such as standard and product definition, data base and data dissemination, precise orbit determination, global gravity field model solutions and regional solutions, solution validation, communication and documentation, and the interfacing to level 3 product scientific users. The central issue of GOCE data processing is, of course, the determination of the global gravity field model using three independent mathematical-numerical techniques which had been designed and pre-developed in the course of several scientific preparatory studies of ESA: 1. The direct solution which is a least squares adjustment technique based on a pre-conditioned conjugated gradient method (PCGM). The method is capable of efficiently transforming the calibrated and validated SST and SGG observations directly or via lumped coefficients into harmonic coefficients of the gravitational potential. 2. The time-wise approach considers both SST and SGG data as a time series. For an idealized repeat mission such a time series can be very efficiently transformed into lumped coefficients using fast Fourier techniques. For a realistic mission scenario this transformation has to be extended by an iteration process. 3. The space-wise approach which, after having transformed the original observations onto a spatial geographical grid, transforms the pseudo-observations into harmonic coefficients using a fast collocation technique. A successful mission presupposed, GOCE will finally deliver the Earth's gravity field with a resolution of about 70 km half wavelength and a global geoid with an accuracy of about 1 cm.

Suenkel, H.; Suenkel, H.

2001-12-01

314

Integrating a Gravity Simulation and Groundwater Modeling on the Calibration of Specific Yield for Choshui Alluvial Fan  

NASA Astrophysics Data System (ADS)

For sustainable management, accurate estimation of recharge can provide critical information. The accuracy of estimation is highly related to uncertainty of specific yield (Sy). Because Sy value is traditionally obtained by a multi-well pumping test, the available Sy values are usually limited due to high installation cost. Therefore, this information insufficiency of Sy may cause high uncertainty for recharge estimation. Because gravity is a function of a material mass and the inverse square of the distance, gravity measurement can assist to obtain the mass variation of a shallow groundwater system. Thus, the groundwater level observation data and gravity measurements are used for the calibration of Sy for a groundwater model. The calibration procedure includes four steps. First, gravity variations of three groundwater-monitoring wells, Si-jhou, Tu-ku and Ke-cuo, are observed in May, August and November 2012. To obtain the gravity caused by groundwater variation, this study filters the noises from other sources, such as ocean tide and land subsidence, in the collected data The refined data, which are data without noises, are named gravity residual. Second, this study develops a groundwater model using MODFLOW 2005 to simulate the water mass variation of the groundwater system. Third, we use Newton gravity integral to simulate the gravity variation caused by the simulated water mass variation during each of the observation periods. Fourth, comparing the ratio of the gravity variation between the two data sets, which are observed gravity residuals and simulated gravities. The values of Sy is continuously modified until the gravity variation ratios of the two data sets are the same. The Sy value of Si-jhou is 0.216, which is obtained by the multi-well pumping test. This Sy value is assigned to the simulation model. The simulation results show that the simulated gravity can well fit the observed gravity residual without parameter calibration. This result indicates that the proposed approach is correct and reasonable. In Tu-ku and Ke-cuo, the ratios of the gravity variation between observed gravity residuals and simulated gravities are approximate 1.8 and 50, respectively. The Sy values of these two stations are modified 1.8 and 50 times the original values. These modified Sy values are assigned to the groundwater morel. After the parameter re-assignment, the simulated gravities meet the gravity residuals in these two stations. In conclusion, the study results show that the proposed approach has the potential to identify Sy without installing wells. Therefore, the proposed approach can be used to increase the spatial density of Sy and can conduct the recharge estimation with low uncertainty.

Chang, Liang Cheng; Tsai, Jui pin; Chen, Yu Wen; Way Hwang, Chein; Chung Cheng, Ching; Chiang, Chung Jung

2014-05-01

315

Crustal vertical motion along a profile crossing the Rhine graben from the Vosges to the Black Forest Mountains: Results from absolute gravity, GPS and levelling observations  

NASA Astrophysics Data System (ADS)

The Rhine plain is oriented north-south and limited by the Vosges Mountains (France) to the West and the Black Forest Mountains (Germany) to the East. The present-day tectonic evolution of this system is not well known and many questions are still pending: is the graben subsiding? Are the mountains uplifting? What is the relative behaviour of the three different geological components? In attempting to answer these questions, we compare for the first time in this region time series of absolute gravity (AG) measurements to the available GPS observations at three sites along a profile crossing the Rhine graben. Our reference station is the gravimetric observatory near Strasbourg (J9), located in the Rhine plain where AG measurements are performed regularly since 1997 and where superconducting gravimeter (SG) observations are available almost continuously for 17 years. The secondary sites are the Welschbruch station in the Vosges Mountains where six AG measurements have been conducted since 1997 and the Black Forest Observatory (BFO) where three AG measurements are available. GPS permanent receivers are collocated at the Strasbourg-J9 site since 1999, at the Welschbruch station since 2000, and at BFO since 2002. Levelling data are only available in the BFO region. We compare the long term content of two types of geodetic measurements with special emphasis on the trend despite the limited duration of our data sets. Assuming that the gravity changes are linear in time, we obtain g?=1.9±0.2 ?Gal/yr at Strasbourg-J9, g?=-0.96±0.2 ?Gal/yr at Welschbruch site and g?=2.5±0.5 ?Gal/yr at BFO. The trends according to GPS observations are, respectively: -1.51 ± 0.07 and -0.74 ± 0.10 mm/yr at Strasbourg-J9 and Welschbruch site, respectively; there is no GPS result available at BFO. The AG results for BFO are very questionable, as well as the GPS observations at the Welschbruch station. Nonetheless, Strasbourg-J9 and Welschbruch AG measurements lead to subsidence and uplift, respectively, which are expected results in agreement with GPS at Strasbourg-J9.

Amalvict, M.; Hinderer, J.; Rózsa, S.

2006-01-01

316

Identification of candidate genes for yeast engineering to improve bioethanol production in very high gravity and lignocellulosic biomass industrial fermentations  

PubMed Central

Background The optimization of industrial bioethanol production will depend on the rational design and manipulation of industrial strains to improve their robustness against the many stress factors affecting their performance during very high gravity (VHG) or lignocellulosic fermentations. In this study, a set of Saccharomyces cerevisiae genes found, through genome-wide screenings, to confer resistance to the simultaneous presence of different relevant stresses were identified as required for maximal fermentation performance under industrial conditions. Results Chemogenomics data were used to identify eight genes whose expression confers simultaneous resistance to high concentrations of glucose, acetic acid and ethanol, chemical stresses relevant for VHG fermentations; and eleven genes conferring simultaneous resistance to stresses relevant during lignocellulosic fermentations. These eleven genes were identified based on two different sets: one with five genes granting simultaneous resistance to ethanol, acetic acid and furfural, and the other with six genes providing simultaneous resistance to ethanol, acetic acid and vanillin. The expression of Bud31 and Hpr1 was found to lead to the increase of both ethanol yield and fermentation rate, while Pho85, Vrp1 and Ygl024w expression is required for maximal ethanol production in VHG fermentations. Five genes, Erg2, Prs3, Rav1, Rpb4 and Vma8, were found to contribute to the maintenance of cell viability in wheat straw hydrolysate and/or the maximal fermentation rate of this substrate. Conclusions The identified genes stand as preferential targets for genetic engineering manipulation in order to generate more robust industrial strains, able to cope with the most significant fermentation stresses and, thus, to increase ethanol production rate and final ethanol titers.

2011-01-01

317

Morphology of gravity-wave energy as observed from 4 years (1998-2001) of high vertical resolution U.S. radiosonde data  

Microsoft Academic Search

Gravity-wave energy densities have been derived from 4 years (1998-2001) of U.S. high vertical resolution (~30 m) radiosonde wind and temperature data. This data set includes more than 90 stations that extend from 14°S to 71°N and 135°E to 55°W and cover such varied terrain as tropical islands, midcontinent plains, and mountainous regions, and they extend to the Arctic. This

Ling Wang; Marvin A. Geller

2003-01-01

318

Sensorimotor aspects of high-speed artificial gravity: I. Sensory conflict in vestibular adaptation  

NASA Technical Reports Server (NTRS)

Short-radius centrifugation offers a promising and affordable countermeasure to the adverse effects of prolonged weightlessness. However, head movements made in a fast rotating environment elicit Coriolis effects, which seriously compromise sensory and motor processes. We found that participants can adapt to these Coriolis effects when exposed intermittently to high rotation rates and, at the same time, can maintain their perceptual-motor coordination in stationary environments. In this paper, we explore the role of inter-sensory conflict in this adaptation process. Different measures (vertical nystagmus, illusory body tilt, motion sickness) react differently to visual-vestibular conflict and adapt differently. In particular, proprioceptive-vestibular conflict sufficed to adapt subjective parameters and the time constant of nystagmus decay, while retinal slip was required for VOR gain adaptation. A simple correlation between the strength of intersensory conflict and the efficacy of adaptation fails to explain the data. Implications of these findings, which differ from existing data for low rotation rates, are discussed.

Brown, Erika L.; Hecht, Heiko; Young, Laurence R.

2002-01-01

319

Spectroscopy of high-L Rydberg levels of nickel  

NASA Astrophysics Data System (ADS)

The complex fine structure pattern in high-L ( L > 4) Rydberg levels of nickel were studied using the Resonant Excitation Stark Ionization Spectroscopy (RESIS) technique. A beam of Ni^+ ions, obtained from a Colutron ion source, captured a single electron from a Rb 9F Rydberg target to become highly excited Rydberg levels of neutral Ni. Levels with n=9 and L=5,6,7, and 8 were excited to n=19 or 20 using a Doppler-tuned CO2 laser, resolving the n=9 fine structure pattern, which consists of six levels for each value of L. Analysis of the pattern using the long-range polarization model determined several properties of the 3d^9 ^2D5/2 ground state of Ni^+, including its permanent quadrupole moment and its scalar and tensor dipole polarizabilities.

Keele, Julie A.; Woods, Shannon L.; Hanni, Mark E.; Voigt, Kristen; Lundeen, Stephen R.

2010-03-01

320

Expanding Gravity  

NASA Astrophysics Data System (ADS)

Newton's gravitational constant Gn and Laws of Gravity are based upon observations in our solar system. Mysteries appear when they are used far outside our solar system Apparently, Newton's gravitational constant can not be applied at large distances. Dark matter was needed to explain the observed flat rotational velocity curves of spiral galaxies (Rubin), and of groups of remote galaxies (Zwicky). Our expansion of Newton's gravitational constant Gn as a power series in distance r, is sufficient to explain these observations without using dark matter. This is different from the MOND theory of Milgrom involving acceleration. Also, our Expanded Gravitational Constant (EGC) can show the correct use of the red shift. In addition to the Doppler contribution, there are three other contributions and these depend only upon gravity. Thus, velocity observations only based on the red shift can not be used to support the concept of the expanding universe, the accelerating expansion, or dark energy. Our expanded gravity constant can predict and explain Olbers' paradox (dark sky), and the temperature of the CMB (cosmic microwave background). Thus, CMB may not support the big bang and inflation.

Aisenberg, Sol

2005-04-01

321

Issues of Uncertainty Analysis in High-Level Information Fusion  

Microsoft Academic Search

High-Level Information Fusion (HLIF) utilizes techniques from Low-Level Information Fusion (LLIF) to support situation\\/impact assessment, user involvement, and mission and resource management (SUM). Given the unbounded analysis of situations, events, users, resources, and missions; it is obvious that uncertainty is manifested by the nature of application requirements. In this panel, we seek discussions on methods and techniques to intelligently assess

Erik Blasch; Paulo Cesar G. Da Costa; Kathryn B. Laskey; Dafni Stampouli; Gee Wah Ng; Johan Schubert; Rakesh Nagi; Pierre Valin

2012-01-01

322

High-accurate optical fiber liquid-level sensor  

Microsoft Academic Search

A highly accurate optical fiber liquid level sensor is presented. The single-chip microcomputer is used to process and control the signal. This kind of sensor is characterized by self-security and is explosion-proof, so it can be applied in any liquid level detecting areas, especially in the oil and chemical industries. The theories and experiments about how to improve the measurement

Dexing Sun; Shouliu Chen; Chao Pan; Henghuan Jin

1991-01-01

323

Algorithms, performance, development of the ATLAS High-Level trigger  

NASA Astrophysics Data System (ADS)

The ATLAS trigger system has been used for the online event selection for three years of LHC data-taking and is preparing for the next run. The trigger system consists of a hardware level-1 and a software high-level trigger (HLT) which is implemented in a region-of-interest based level-2 stage and a event filter operating after event building with offline-like software. During the past three years, the luminosity and pile-up (number of collisions per beam crossing) has increased significantly placing escalating demands on the rejection and timing performance. The HLT algorithms advanced during this period to maintain and even improve performance. Also discussed is the work towards the merging of the two HLT levels in to a single level HLT.

Nagano, Kunihiro; Atlas Collaboration

2014-06-01

324

High-fidelity population transfer in a Josephson three-level atom with optimized level anharmonicity  

NASA Astrophysics Data System (ADS)

We propose a theoretical scheme to enhance the fidelity of population transfer in a Josephson three-level atom by optimizing the level anharmonicity. Without the leakage effect, the ideal population transfer can be performed via Raman adiabatic passage. In the general case, we consider the dependence of transfer fidelity on the leakage error, and then present an effective way to implement the high-fidelity population transfer using the optimized level structure. The scheme could offer a potential route towards the robust population transfer with artificial Josephson atoms experimentally.

Feng, Zhi-Bo; Li, M.

2014-05-01

325

A New Exponential Gravity  

NASA Astrophysics Data System (ADS)

We propose a new exponential f(R) gravity model with f(R) = (R - ?c) e ?(c/R)n and n > 3, ? >= 1, c > 0 to explain late-time acceleration of the universe. At the high curvature region, the model behaves like the ? CDM model. In the asymptotic future, it reaches a stable de-Sitter spacetime. It is a cosmologically viable model and can evade the local gravity constraints easily. This model shares many features with other f(R) dark energy models like Hu-Sawicki model and Exponential gravity model. In it the dark energy equation of state is of an oscillating form and can cross phantom divide line ?de = -1. In particular, in the parameter range 3 < n <= 4, ? ~ 1, the model is most distinguishable from other models. For instance, when n = 4, ? = 1, the dark energy equation of state will cross -1 in the earlier future and has a stronger oscillating form than the other models, the dark energy density in asymptotical future is smaller than the one in the high curvature region. This new model can evade the local gravity tests easily when n > 3 and ? > 1.

Xu, Qiang; Chen, Bin

2014-01-01

326

Aeon: Synthesizing Scheduling Algorithms from High-Level Models  

NASA Astrophysics Data System (ADS)

This paper describes the aeon system whose aim is to synthesize scheduling algorithms from high-level models. A eon, which is entirely written in comet, receives as input a high-level model for a scheduling application which is then analyzed to generate a dedicated scheduling algorithm exploiting the structure of the model. A eon provides a variety of synthesizers for generating complete or heuristic algorithms. Moreover, synthesizers are compositional, making it possible to generate complex hybrid algorithms naturally. Preliminary experimental results indicate that this approach may be competitive with state-of-the-art search algorithms.

Monette, Jean-Noël; Deville, Yves; van Hentenryck, Pascal

327

High Level Waste (HLW) Feed Process Control Strategy  

SciTech Connect

The primary purpose of this document is to describe the overall process control strategy for monitoring and controlling the functions associated with the Phase 1B high-level waste feed delivery. This document provides the basis for process monitoring and control functions and requirements needed throughput the double-shell tank system during Phase 1 high-level waste feed delivery. This document is intended to be used by (1) the developers of the future Process Control Plan and (2) the developers of the monitoring and control system.

STAEHR, T.W.

2000-06-14

328

High level radioactive waste management facility design criteria  

SciTech Connect

This paper discusses the engineering systems for the structural design of the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). At the DWPF, high level radioactive liquids will be mixed with glass particles and heated in a melter. This molten glass will then be poured into stainless steel canisters where it will harden. This process will transform the high level waste into a more stable, manageable substance. This paper discuss the structural design requirements for this unique one of a kind facility. A special emphasis will be concentrated on the design criteria pertaining to earthquake, wind and tornado, and flooding.

Sheikh, N.A.; Salaymeh, S.R.

1993-10-01

329

Geoid for Austria - Regional gravity FIELD improved  

NASA Astrophysics Data System (ADS)

The project 'Geoid for Austria - Regional gravity FIELD improved' (GARFIELD) is a current initiative for the generation of a new high-quality gravity field solution for the Austrian region, which overcomes the inconsistencies between previous geoid solutions and geoid heights from GPS/leveling campaigns. The optimum combination of the complementary data types of satellite observations and all available terrestrial gravity field measurements in Austria and neighbouring countries will be essential. The Least Squares Collocation (LSC) approach will serve as reference method for the gravity field computation. In this context, GOCE gradients should be used as in-situ observations. Alternatively to LSC, a Gauss-Markov model with parametrization as Radial Basis Functions will be implemented. For a successful data combination, the Remove-Compute-Restore technique will be revised to avoid a double consideration of the topographic masses when performing long- and short-wavelength signal reductions. This contribution should give an overview about methods, developments and the current status of the project GARFIELD.

Rieser, Daniel; Pock, Christian; Mayer-Gürr, Torsten; Kühtreiber, Norbert

2013-04-01

330

Unified description of screened modified gravity  

NASA Astrophysics Data System (ADS)

We consider modified gravity models driven by a scalar field whose effects are screened in high density regions due to the presence of nonlinearities in its interaction potential and/or its coupling to matter. Our approach covers chameleon, f(R) gravity, dilaton and symmetron models and allows a unified description of all these theories. We find that the dynamics of modified gravity are entirely captured by the time variation of the scalar field mass and its coupling to matter evaluated at the cosmological minimum of its effective potential, where the scalar field has sat since an epoch prior to big bang nucleosynthesis. This new parametrization of modified gravity allows one to reconstruct the potential and coupling to matter and therefore to analyze the full dynamics of the models, from the scale dependent growth of structures at the linear level to nonlinear effects requiring N-body simulations. This procedure is illustrated with explicit examples of reconstruction for chameleon, dilaton, f(R) and symmetron models.

Brax, Philippe; Davis, Anne-Christine; Li, Baojiu; Winther, Hans A.

2012-08-01

331

High-Temperature Leaching of an Actinide-Bearing, Simulated High-Level Waste Glass.  

National Technical Information Service (NTIS)

The chemical durability of a simulated high-level waste glass when exposed to high-temperature geologic solutions was investigated. In this study, simulated high-level waste glass-beads (76 to 68 glass)l doped with technetium, uranium, neptunium, plutoniu...

J. H. Westsik C. O. Harvey W. L. Kuhn

1983-01-01

332

Low voltage to high voltage level shifter and related methods  

NASA Technical Reports Server (NTRS)

A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

2006-01-01

333

High latitude gravity waves at the Venus cloud tops as observed by the Venus Monitoring Camera on board Venus Express  

NASA Astrophysics Data System (ADS)

High resolution images of Venus Northern hemisphere obtained with the Venus Monitoring Camera (VMC/VEx) allow studying small-scale dynamical phenomena at the cloud tops (˜62-70 km altitude) including features like wave trains. A systematic visual search of these waves was performed; more than 1500 orbits were analyzed and wave patterns were observed in more than 300 images. Four types of waves were identified in VMC images on the base of their morphology: long, medium, short and irregular type waves. With the aim to characterize the wave types and their possible excitation source, we retrieved wave properties such as location (latitude and longitude), local time, solar zenith angle, packet length and width, orientation, and wavelength of each wave. The long type waves appear as long and narrow straight features extending more than a few hundreds kilometers and with wavelengths between 7 and 17 km. Medium type waves exhibit irregular wavefronts extending more than 100 km and with wavelengths in the range 8-21 km. Short wave packets have a width of several tens of kilometers and extend to few hundreds kilometers and are characterized by smaller wavelengths (3-16 km). Irregular wave fields appear to be the result of wave interference. The waves are often identified in all VMC filters and are mostly found in the cold collar region at high latitudes (60-80°N) and are concentrated above Ishtar Terra, a continental size highland that includes the highest mountain belts of the planet. The high speed of the Venus Express spacecraft close to the pericentre does not allow to measure phase speed of waves due to the short temporal interval between image pairs. The lack of information on phase velocities does not allow us to establish with absolute confidence the nature of these waves. However, by comparing the morphology and properties of the wave features observed in VMC images to those seen by previous observations it is reasonable to assume that the waves studied here are gravity waves.

Piccialli, A.; Titov, D. V.; Sanchez-Lavega, A.; Peralta, J.; Shalygina, O.; Markiewicz, W. J.; Svedhem, H.

2014-01-01

334

Model studies of time-dependent ducting for high-frequency gravity waves and associated airglow responses in the upper atmosphere  

NASA Astrophysics Data System (ADS)

This doctoral dissertation has mainly concentrated on modeling studies of shorter period acoustic-gravity waves propagating in the upper atmosphere. Several cases have been investigated in the literature, which are focusing on the propagation characteristics of highfrequency gravity wave packets. The dissertation consists of five main divisions of which each has its own significance to be addressed, and these five chapters are also bridged in order with each other to present a theme about gravity wave ducting dynamics, energetics, and airglows. The first chapter is served as an introduction of the general topic about atmospheric acoustic-gravity waves. Some of the historical backgrounds are provided as an interesting refreshment and also as a motivation reasoning this scientific research for decades. A new 2-D, time-dependent, and nonlinear model is introduced in the second chapter (the AGE-TIP model, acronymically named atmospheric gravity waves for the Earth plus tides and planetary waves). The model is developed during this entire doctoral study and has carried out almost all research results in this dissertation. The third chapter is a model application for shorter period gravity waves ducted in a thermally stratified atmosphere. In spite of mean winds the thermal ducting occurs because ducted waves are fairly common occurrences in airglow observations. One-dimensional Fourier analysis is applied to identify the ducted wave modes that reside within multiple thermal ducts. Besides, the vertical energy flux and the wave kinetic energy density are derived as wave diagnostic variables to better understand the time-resolved vertical transport of wave energy in the presence of multiple thermal ductings. The fourth chapter is also a model application for shorter period gravity waves, but it instead addresses the propagation of high-frequency gravity waves in the presence of mean background wind shears. The wind structure acts as a significant directional filter to the wave spectra and hence causes noticeable azimuthal variations at higher altitudes. In addition to the spectral analysis applied previously the wave action has been used to interpret the energy coupling between the waves and the mean flow among some atmospheric regions, where the waves are suspected to extract energy from the mean flow at some altitudes and release it to other altitudes. The fifth chapter is a concrete and substantial step connecting theoretical studies and realistic observations through nonlinearly coupling wave dynamic model with airglow chemical reactions. Simulated O (1S) (557.7 nm) airglow images are provided so that they can be compared with observational airglow images. These simulated airglow brightness variations response accordingly with minor species density fluctuations, which are due to propagating and ducting nonlinear gravity waves within related airglow layers. The thermal and wind structures plus the seasonal and geographical variabilities could significantly influence the observed airglow images. By control modeling studies the simulations can be used to collate with concurrent observed data, so that the incoherencies among them could be very useful to discover unknown physical processes behind the observed wave scenes.

Yu, Yonghui

335

High levels of fluctuating asymmetry in isolated stickleback populations  

PubMed Central

Background Fluctuating asymmetry (FA), defined as small random deviations from the ideal bilateral symmetry, has been hypothesized to increase in response to both genetic and environmental stress experienced by a population. We compared levels of FA in 12 bilateral meristic traits (viz. lateral-line system neuromasts and lateral plates), and heterozygosity in 23 microsatellite loci, among four marine (high piscine predation risk) and four pond (zero piscine predation risk) populations of nine-spined sticklebacks (Pungitius pungitius). Results Pond sticklebacks had on average three times higher levels of FA than marine fish and this difference was highly significant. Heterozygosity in microsatellite markers was on average two times lower in pond (HE ? 0.3) than in marine (HE ? 0.6) populations, and levels of FA and heterozygosity were negatively correlated across populations. However, after controlling for habitat effect on heterozygosity, levels of FA and heterozygosity were uncorrelated. Conclusions The fact that levels of FA in traits likely to be important in the context of predator evasion were elevated in ponds compared to marine populations suggests that relaxed selection for homeostasis in ponds lacking predatory fish may be responsible for the observed habitat difference in levels of FA. This inference also aligns with the observation that the levels of genetic variability across the populations did not explain population differences in levels of FA after correcting for habitat effect. Hence, while differences in strength of selection, rather than in the degree of genetic stress could be argued to explain habitat differences in levels of FA, the hypothesis that increased FA in ponds is caused by genetic stress cannot be rejected.

2012-01-01

336

Vertical fluctuation energy in United States high vertical resolution radiosonde data as an indicator of convective gravity wave sources  

Microsoft Academic Search

Convectively generated internal gravity waves at extratropical latitudes are difficult to identify by climatological analysis of the temperature and horizontal wind fields from radiosonde profiles using traditional analysis methods. Here, we show that, by analyzing ascent rate profiles (we define a new variable, “vertical fluctuation energy (VE)”), we can identify convection sources in climatological analyses. Analysis of a 9-year time

Jie Gong; Marvin A. Geller

2010-01-01

337

Vertical fluctuation energy in United States high vertical resolution radiosonde data as an indicator of convective gravity wave sources  

Microsoft Academic Search

Convectively generated internal gravity waves at extratropical latitudes are difficult to identify by climatological analysis of the temperature and horizontal wind fields from radiosonde profiles using traditional analysis methods. Here, we show that, by analyzing ascent rate profiles (we define a new variable, ``vertical fluctuation energy (VE)''), we can identify convection sources in climatological analyses. Analysis of a 9-year time

Jie Gong; Marvin A. Geller

2010-01-01

338

Atom interferometric gravity gradiometer: Disturbance compensation and mobile gradiometry  

Microsoft Academic Search

First ever mobile gravity gradient measurement based on Atom Interferometric sensors has been demonstrated. Mobile gravity gradiometers play a significant role in high accuracy inertial navigation systems in order to distinguish inertial acceleration and acceleration due to gravity. The gravity gradiometer consists of two atom interferometric accelerometers. In each of the accelerometer an ensemble of laser cooled Cesium atoms is

Chetan Mahadeswaraswamy

2009-01-01

339

A comparison of high-level waste form characteristics  

SciTech Connect

There are currently about 1055 million curies of high-level waste with a thermal output of about 2950 kilowatts (KW) at four sites in the United States: West Valley Demonstration Project (WVDP), Savannah River Site (SRS), Hanford Site (HANF), and Idaho National Engineering Laboratory (INEL). These quantities are expected to increase to about 1200 million curies and 3570 kw by the end of year 2020. Under the Nuclear Waste Policy Act, this high-level waste must ultimately be disposed of in a geologic repository. Accordingly, canisters of high-level waste immobilized in borosilicate glass or glass-ceramic mixtures are to be produced at the four sites and stored there until a repository becomes available. Data on the estimated production schedules and on the physical, chemical, and radiological characteristics of the canisters of immobilized high-level waste have been collected in OCRWM's Waste Characteristics Data Base, including recent updates an revisions. Comparisons of some of these data for the four sites are presented in this report. 14 refs., 3 tabs.

Salmon, R.; Notz, K.J.

1991-01-01

340

Development of a High Level Waste Tank Inspection System  

Microsoft Academic Search

The Westinghouse Savannah River Technology Center was requested by it`s sister site, West Valley Nuclear Service (WVNS), to develop a remote inspection system to gather wall thickness readings of their High Level Waste Tanks. WVNS management chose to take a proactive approach to gain current information on two tanks t hat had been in service since the early 70`s. The

D. K. Appel; M. W. Loibl; D. C. Meese

1995-01-01

341

Fixed Point Data Type Modeling for High Level Synthesis  

Microsoft Academic Search

A methodology to automatically convert fixed point data type representations into integer data types for high level synthesis is presented in this work. Our method converts all major C operations using fixed point data types into integer data types, models quantization and overflow modes, type conversion and casting. The conversion rule for each operation is described in detail as well

Benjamin Carrión Schäfer; Yusuke Iguchi; Wataru Takahashi; Shingo Nagatani; Kazutoshi Wakabayashi

2010-01-01

342

High Level Waste Lag Storage and Feed Blending  

Microsoft Academic Search

SRTC performed small-scale tests to determine the behavior associated with blending streams in the High-level Waste (HLW) Lag Storage and Feed Blending Process System for the Hanford Waste Treatment and Immobilization Plant (WTP). The work reported here was planned and designed in response to the test specification. The Office of River Protection Hanford Waste Treatment and Immobilization Plant consists of

2004-01-01

343

The Siemens high-level synthesis system CALLAS  

Microsoft Academic Search

In this paper we present the Siemens high-level synthesis system CALLAS and describe its design methodology and synthesis strategy. It supports the synthesis of control-dominated applications and uses a VHDL subset for the algorithmic specification. Its main feature can be characterized as \\

J. Biesenack; M. Koster; A. Langmaier; S. Ledeux; S. Marz; Michael Payer; Michael Pilsl; S. Rumler; H. Soukup; Norbert Wehn; Peter Duzy

1993-01-01

344

A Preview of High School Level Economic Software.  

ERIC Educational Resources Information Center

The purpose of this study was to locate and evaluate high-school-level economic software compatible with an Apple II or IIe computer. To identify software, computer searches were run, bibliographies were scanned, and reviews were collected. Only software that was recommended by some outside source was included in the evaluation. The following…

Kincade, Jeannine H.

345

High Level Exploration of Quantum-Dot Cellular Automata (QCA)  

Microsoft Academic Search

In this work, we present a high level evaluation of an emerging nanotechnology to determine a set of technology requirements. The technology under question is Quantum-Dot Cellular Automata (QCA). As a vehicle, we present two different QCA circuits and evaluate the technology requirements based on the specifications of these circuits. These circuits are a simple 4-bit arithmetic logic unit (ALU)

K. Walus; G. Schulhof; G. A. Jullien

2004-01-01

346

Turning High-Level Live Sequence Charts into Automata  

Microsoft Academic Search

Message Sequence Charts (MSCs) are a widely used sce- nario notation. However, we believe that this language lacks message abstraction and the ability to express whether a scenario is an example or a universal rule. Live Sequence Charts (LSCs) improve MSCs by solving these two short- comings. However, LSCs have no formally dened high-level structuring mechanism. We extend LSCs with

Yves Bontemps; Patrick Heymans

2002-01-01

347

Humanoid Robot Painter: Visual Perception and High-Level Planning  

Microsoft Academic Search

This paper presents visual perception discovered in high-level manipulator planning for a robot to reproduce the procedure involved in human painting. First, we apply a technique of 2D object segmentation that considers region similarity as an objective function and edge as a constraint with artificial intelligent used as a criterion function. The system can segment images more effectively than most

Miti Ruchanurucks; Shunsuke Kudoh; Koichi Ogawara; Takaaki Shiratori; Katsushi Ikeuchi

2007-01-01

348

A high-level block-diagram signal processing language  

Microsoft Academic Search

The model of discrete-time computation underlying most block diagram languages makes them inappropriate for many important signal processing algorithms. A conceptual framework for a general high-level block diagram programming system is proposed. This framework, the closure model, is motivated by the representation of functions used in applicative languages such as LISP. An experimental block diagram language, BDL, based on this

G. Kopec

1979-01-01

349

Theory and Methods for Supporting High Level Military Decisionmaking.  

National Technical Information Service (NTIS)

In this report, the authors describe an approach to high-level decision support for a Joint Forces Air Component Commander in combat operations or a Chief of Staff in defense planning. Their central theme is the fundamental importance of dealing effective...

J. P. Kahan P. K. Davis

2007-01-01

350

A high-level specification for virtual providers  

Microsoft Academic Search

Abstract: In this paper we define a high-level model to mathematically capture the semantical meaning of abstract Virtual Providers (VP), their instantiation and their composition into rich mediator structures. We will show how this model can be sucess- fully applied to two application scenarios, Web service protocol mediation and Semantic Web Service discovery. Keywords: Virtual Provider, Mediator, Protocol Mediation, Semantic

Michael Altenhofen; Andreas Friesen; Jens Lemcke; Egon Borger

2006-01-01

351

HIL: A High-Level Scripting Language for Entity Integration  

Microsoft Academic Search

We introduce HIL, a high-level scripting language for entity res- olution and integration. HIL aims at providing the core logic for complex data processing flows that aggregate facts from large col- lections of structured or unstructured data into clean, unified enti- ties. Such flows typically include many stages of processing that start from the outcome of information extraction and continue

Mauricio Hernández; Georgia Koutrika; Rajasekar Krishnamurthy; Lucian Popa; Ryan Wisnesky

2013-01-01

352

Hierarchical High Level Petri Nets for Complex System Analysis  

Microsoft Academic Search

The class of Hierarchical High Level Petri Nets (HHPNs) is introduced. HHPNs provide a framework for a modular specification of complex parallel and concurrent systems which supports top-down and bottom-up design. Apart from specification convenience HHPNs can be analysed very efficiently according to functional aspects of the modelled system. Analysis is based on a divide and conquer approach combined with

Peter Buchholz

1994-01-01

353

Device enables calibration of microphones at high sound pressure levels  

NASA Technical Reports Server (NTRS)

Coupling device accurately calibrates microphones at high sound pressure intensities. The system which uses a liquid as the coupling medium can operate in an automatic mode by using a standard microphone as a control sensor. Feedback from the standard microphone controls the calibration signal level.

Gillen, A.

1967-01-01

354

Nonlinear Behavior of CRF Device at High Power Level  

Microsoft Academic Search

This paper investigates the nonlinear behavior of CRF filters. First, measurements carried out on stand-alone resonators underline the impact of resonator size and loading layer thickness on linearity. Then, a comparison between a BAW filter and a CRF filter is presented regarding second order nonlinearities. Finally, the nonlinear behavior of CRF filters at high power levels has been investigated through

L. Mourot; P. Bar; A. Giry; S. Joblot; G. Parat; S. Bila; J.-F. Carpentier

2009-01-01

355

Time Management in the DoD High Level Architecture  

Microsoft Academic Search

Recently, a considerable amount of effort in the U.S.Department of Defense has been devoted to definingthe High Level Architecture (HLA) for distributedsimulations. This paper describes the timemanagement component of the HLA that defines themeans by which individual simulations (calledfederates) advance through time. Time managementincludes synchronization mechanisms to ensure eventordering when this is needed. The principal challengeof the time management structure

Richard M. Fujimoto; Richard M. Weatherly

1996-01-01

356

Truck cask design for shipping Defense High Level Waste  

Microsoft Academic Search

The Defense High Level Waste (DHLW) cask is a Type B packaging currently under development by the US Department of Energy (DOE). This truck cask has been designed to initially transport borosilicate glass waste from the Defense Waste Processing Facility (DWPF) to the Waste Isolation Pilot Plant (WIPP). Specific program activities include designing, testing, certifying, and fabricating a prototype legal-weight

M. M. Madsen; A. Zimmer

1985-01-01

357

Typewriter Modifications for Persons Who Are High-Level Quadriplegics.  

ERIC Educational Resources Information Center

Standard, common electric typewriters are not completely suited to the needs of a high-level quadriplegic typing with a mouthstick. Experiences show that for complete control of a typewriter a mouthstick user needs the combined features of one-button correction, electric forward and reverse indexing, and easy character viewing. To modify a…

O'Reagan, James R.; And Others

358

Deployment of the ATLAS High-Level Trigger  

Microsoft Academic Search

The ATLAS combined test beam in the second half of 2004 saw the first deployment of the ATLAS High-Level Trigger (HLT). The next steps are deployment on the pre-series farms in the experimental area during 2005, commissioning and cosmics tests with the full detector in 2006 and collisions in 2007. This paper reviews the experience gained in the test beam,

A. dos Anjos; S. Armstrong; J. T. M. Baines; H. P. Beck; C. P. Bee; M. Biglietti; J. A. Bogaerts; M. Bosman; D. Burckhart; M. Caprini; B. Caron; P. Casado; G. Cataldi; D. Cavalli; M. Ciobotaru; G. Comune; P. Conde; A. Corso-Radu; G. Crone; D. Damazio; A. de Santo; M. Diaz-Gomez; A. Di Mattia; M. Dobson; N. Ellis; D. Emeliyanov; B. Epp; S. Falciano; R. Ferrari; D. Francis; S. Gadomski; S. Gameiro; H. Garitaonandia; S. George; V. Ghete; R. Goncalo; B. Gorini; M. Gruwe; C. Haeberli; J. Haller; M. Joos; S. Kabana; A. Kazarov; A. Khomich; G. Kilvington; J. Kirk; S. Kolos; N. Konstantinidis; A. Kootz; A. Lankford; G. Lehmann; A. Lowe; L. Luminari; T. Maeno; J. Masik; C. Meirosu; C. Meessen; A. G. Mello; R. Moore; P. Morettini; A. Negri; N. Nikitin; A. Nisati; C. Osuna; C. Padilla; N. Panikashvili; F. Parodi; E. Pasqualucci; V. P. Reale; J. Petersen; J. L. Pinfold; P. Pinto; Z. Qian; S. Resconi; S. Rosati; C. Santamarina; D. A. Scannicchio; C. Schiavi; E. Segura; J. M. Seixas; S. Sivoklokov; J. Sloper; A. Sobreira; I. Soloviev; R. Soluk; S. Stancu; E. Stefanidis; S. Sushkov; M. Sutton; S. Tapprogge; S. Tarem; E. Thomas; F. Touchard; L. Tremblet; G. Unel; G. Usai; W. Vandelli; B. V. Pinto; A. Ventura; V. Vercesi; T. Wengler; P. Werner; S. J. Wheeler; F. J. Wickens; W. Wiedenmann; M. Wielers; M. Wiesmann; Y. Yasu; G. Zobernig

2006-01-01

359

Level 1 Tornado PRA for the High Flux Beam Reactor.  

National Technical Information Service (NTIS)

This report describes a risk analysis primarily directed at providing an estimate for the frequency of tornado induced damage to the core of the High Flux Beam Reactor (HFBR), and thus it constitutes a Level 1 Probabilistic Risk Assessment (PRA) covering ...

C. S. Conrad G. E. Bozoki

1994-01-01

360

In-situ nitrite analysis in high level waste tanks  

SciTech Connect

The Savannah River Site produces special nuclear materials used in the defense of the United States. Most of the processes at SRS are primarily chemical separations and purifications. In-situ chemical analyses help improve the safety, efficiency and quality of these operations. One area where in situ fiberoptic spectroscopy can have a great impact is the management of high level radioactive waste. High level radioactive waste at SRS is stored in more than 50 large waste tanks. The waste exists as a slurry of nitrate salts and metal hydroxides at pH`s higher than 10. Sodium Nitrite is added to the tanks as a corrosion inhibitor. In-situ fiberoptic probes are being developed to measure the nitrate, nitrite and hydroxide concentrations in both liquid and solid fractions. Nitrite levels can be measured between 0.01M and 1M in a 1mm pathlength optical cell.

O`Rourke, P.E.; Prather, W.S.; Livingston, R.R.

1992-09-01

361

In-situ nitrite analysis in high level waste tanks  

SciTech Connect

The Savannah River Site produces special nuclear materials used in the defense of the United States. Most of the processes at SRS are primarily chemical separations and purifications. In-situ chemical analyses help improve the safety, efficiency and quality of these operations. One area where in situ fiberoptic spectroscopy can have a great impact is the management of high level radioactive waste. High level radioactive waste at SRS is stored in more than 50 large waste tanks. The waste exists as a slurry of nitrate salts and metal hydroxides at pH's higher than 10. Sodium Nitrite is added to the tanks as a corrosion inhibitor. In-situ fiberoptic probes are being developed to measure the nitrate, nitrite and hydroxide concentrations in both liquid and solid fractions. Nitrite levels can be measured between 0.01M and 1M in a 1mm pathlength optical cell.

O'Rourke, P.E.; Prather, W.S.; Livingston, R.R.

1992-01-01

362

Detection of high risk campylobacteriosis clusters at three geographic levels.  

PubMed

Campylobacteriosis is a leading cause of bacterial gastroenteritis in the United States and many other developed countries. Understanding the spatial distribution of this disease and identifying high-risk areas is vital to focus resources for prevention and control measures. In addition, determining the appropriate scale for geographical analysis of surveillance data is an area of concern to epidemiologists and public health officials. The purpose of this study was to (i) compare standardized risk estimates for campylobacteriosis in Tennessee over three distinct geographical scales (census tract, zip code and county subdivision), and (ii) identify and investigate high-risk spatial clustering of campylobacteriosis at the three geographical scales to determine if clustering is scale dependent. Significant high risk clusters (P <0.05) were detected at all three spatial scales. There were overlaps in regions of high-risk and clusters at all three geographic levels. At the census tract level, spatial analysis identified smaller clusters of finer resolution and detected more clusters than the other two levels. However, data aggregation at zip code or county subdivision yielded similar findings. The importance of this line of research is to create a framework whereby economically efficient disease control strategies become more attainable through improved geographical precision and risk detection. Accurate identification of disease clusters for campylobacteriosis can enable public health personnel to focus scarce resources towards prevention and control programmes on the most at-risk populations. Consistent results at multiple spatial levels highlight the robustness of the geospatial techniques utilized in this study. Furthermore, analyses at the zip code and county subdivision levels can be useful when address level information (finer resolution data) are not available. These procedures may also be used to help identify regionally specific risk factors for campylobacteriosis. PMID:22109864

Weisent, Jennifer; Rohrbach, Barton; Dunn, John R; Odoi, Agricola

2011-11-01

363

Extremely high urine arsenic level after remote seafood ingestion.  

PubMed

Urine testing for heavy metal concentrations is increasingly performed in the outpatient setting as a part of laboratory evaluation for neuropathy. Abnormal urine arsenic levels due to dietary intake of organic arsenic can lead to unnecessary chelation therapy. A 54-year-old man underwent a 24-hour urine collection for heavy metal concentrations in evaluation of paresthesia of the right foot. The total arsenic level was 8880 ?g/d with concentrations of 4749 ?g/L and 3769 ?g/g creatinine. He was urgently referred to the toxicology clinic for consideration of chelation therapy. History revealed consumption of 2 lobster tails 5 days before the testing. Speciation was then performed on the original urine specimen and revealed an organic arsenic concentration of 4332 ?g/L. No inorganic or methylated arsenic was detected. Repeat testing after abstaining from seafood demonstrated a total arsenic level of 50 ?g/d with concentrations of 30 ?g/L and 21 ?g/g creatinine. Our patient demonstrates the highest level of arsenobetaine reported in the literature, and this level is higher than expected for a person who had not consumed seafood for 5 days before testing. The high levels may be due to consumption of food that he did not recognize as containing arsenobetaine or that his clearance of arsenobetaine from the ingested lobster is slower than published ranges. This case demonstrates the importance of speciation when measuring urine arsenic levels to avoid unnecessary chelation therapy. PMID:22407195

Nañagas, Kristine A; Tormoehlen, Laura M

2014-01-01

364

Gravity waves and gravity wave "breaking" as contributors to aviation turbulence  

NASA Astrophysics Data System (ADS)

Turbulence is a well-known hazard to aviation that is responsible for numerous injuries each year, with occasional fatalities, and results in millions of dollars of operational costs to airlines each year. It has been widely accepted that aviation-scale turbulence that occurs in clear air (CAT) at upper levels (upper troposphere and lower stratosphere) has its origins in Kelvin-Helmholtz instabilities induced by enhanced shears and reduced Richardson numbers associated with the jet stream and upper level fronts. However, it is becoming increasingly apparent that gravity waves and gravity wave "breaking" also play a major role in instigating turbulence that affects aviation. Gravity waves and inertia-gravity waves may be produced by a variety of sources, but one major source that impacts aviation seems to be those produced by convection. Several examples of high-resolution numerical simulations that are based on actual encounters with turbulence by commercial aircraft will be presented to demonstrate these situations. Implications for aviation-scale turbulence forecasting will also be discussed.

Sharman, R.; Lane, T. P.; Trier, S. B.; Fovell, R. G.

2012-12-01

365

Gravity Launch  

NSDL National Science Digital Library

In this online game, learners attempt to send a rocket ship to various targets. Learners can adjust the angle and thrust of the rocket before it is launched. The game simulates the pull of gravity on the rocket from the Earth and Moon. When learners set up a free account at Kinetic City, they can answer bonus questions at the end of the activity as a quick assessment. As a larger assessment, learners can complete the Smart Attack game after they've completed several activities.

Science, American A.

2009-01-01

366

Gravity wave kinetic, potential, and vertical fluctuation energies as indicators of different frequency gravity waves  

Microsoft Academic Search

An advantage of examining atmospheric gravity waves using high vertical-resolution radiosonde data over other measurement techniques is that horizontal wind, temperature, and vertical ascent rate can be measured directly. This allows the kinetic, potential, and vertical velocity fluctuation energies to be derived independently. Each of these gravity wave energies is shown to have sensitivity to different gravity wave frequencies. Observed

Marvin A. Geller; Jie Gong

2010-01-01

367

Estimation of Error Covariance Functions Using Gravity Gradiometry and Surface Gravity Data  

Microsoft Academic Search

The GOCE mission will perform two kinds of measurements: High-low Satellite to Satel- lite Tracking (SST) and Satellite Gravity Gradiome- try (SGG). Some experience from airborne- gradiometry has been gained from the well known Oklahoma experiment. However, the observation of gravity gradients by an electrostatic gravity gradi- ometer on board a satellite is a completely new technique. Many calibration tasks

D. Arabelos; P. Papaparaskevas

368

Superconducting gravity gradiometer for sensitive gravity measurements. I. Theory  

SciTech Connect

Because of the equivalence principle, a global measurement is necessary to distinguish gravity from acceleration of the reference frame. A gravity gradiometer is therefore an essential instrument needed for precision tests of gravity laws and for applications in gravity survey and inertial navigation. Superconductivity and SQUID (superconducting quantum interference device) technology can be used to obtain a gravity gradiometer with very high sensitivity and stability. A superconducting gravity gradiometer has been developed for a null test of the gravitational inverse-square law and space-borne geodesy. Here we present a complete theoretical model of this instrument. Starting from dynamical equations for the device, we derive transfer functions, a common mode rejection characteristic, and an error model of the superconducting instrument. Since a gradiometer must detect a very weak differential gravity signal in the midst of large platform accelerations and other environmental disturbances, the scale factor and common mode rejection stability of the instrument are extremely important in addition to its immunity to temperature and electromagnetic fluctuations. We show how flux quantization, the Meissner effect, and properties of liquid helium can be utilized to meet these challenges.

Chan, H.A.; Paik, H.J.

1987-06-15

369

Detection of High-Potential Oil and Gas Fields Using Normalized Full Gradient of Gravity Anomalies: A Case Study in the Tabas Basin, Eastern Iran  

NASA Astrophysics Data System (ADS)

The normalized full gradient (NFG) represents the full gradient of the gravity anomaly at a point divided by the average of the full gradient at the same point. The NFG minimum between two maxima in an NFG section or a closed minimum surrounded by closed maxima on an NFG map may indicate density-deficient anomalies closely related to possible oil-gas reservoirs. On a cross-section, closed minima can be used to estimate the depth to centers of possible hydrocarbon reservoirs. The NFG map can also be used to locate oil-gas exploratory wells for estimation of the depth of possible reservoirs. The objective of this paper is to use two and three-dimensional (2D and 3D) NFG on gravity data of the Tabas basin in Yazd province, eastern Iran. A hypothetical model is first considered to explore the NFG characteristics and their relationship with the geometry of the model. The physical properties of the model are then studied to simplify the interpretation of real data. Finally 2D and 3D NFG models are developed for real gravity data to predict the location of any possible high potential oil-gas reservoirs. The results obtained indicate two zones in the northern and central parts of the Tabas basin suitable for hydrocarbon prospecting. However, the favorable zone located in the middle of the basin in which anticline E is detected at a depth of 5-7 km is more important for the purpose of hydrocarbon exploration.

Aghajani, Hamid; Moradzadeh, Ali; Zeng, Hualin

2011-10-01

370

Gravity Base Station Descriptions.  

National Technical Information Service (NTIS)

Descriptions of gravity base stations occupied by the Woods Hole Oceanographic Institution during the years 1962 through September 1973 are presented. The measurements were made with LaCoste and Romberg Geodtic Gravity Meter No. G-18. The gravity values, ...

C. Bowin L. Gove

1974-01-01

371

Combined absolute and relative gravity measurement for microgravity monitoring in Aso volcanic field  

NASA Astrophysics Data System (ADS)

Absolute measurement with a portable A10-017 absolute gravimeter at some benchmarks in the Aso volcanic field are valuable for reducing uncertainties of regional gravity variations and will be useful for delineating the long term trends of gravity changes. A10 absolute gravimeter is a new generation of portable absolute instrument and has accuracy 10 microGal. To further the development of a high precision gravity data, we also conducted measurement using two relative gravimeter (Scintrex CG-5 [549] and LaCoste type G-1016) to be combined with an A10 absolute gravimeter. The using absolute gravimeter along with relative gravimeter can reduce drift correction factor and improve the result of gravity change data in microgravity monitoring. Microgravity monitoring is a valued tool for mapping the redistribution of subsurface mass and for assessing changes in the fluid as a dynamic process in volcanic field. Gravity changes enable the characterization of subsurface processes: i.e., the mass of the intrusion or hydrothermal flow. A key assumption behind gravity monitoring is that changes in earth's gravity reflect mass-transport processes at depth [1]. The absolute gravity network was installed at seven benchmarks using on May 2010, which re-occupied in October 2010, and June 2011. The relative gravity measurements were performed at 28 benchmarks in one month before the eruption on May 2011 and then followed by series of gravity monitoring after the eruption in every three to five months. Gravity measurements covered the area more than 60 km2 in the west side of Aso caldera. Some gravity benchmarks were measured using both absolute and relative gravimeter and is used as the reference benchmarks. In longer time period, the combined gravity method will improve the result of gravity change data for monitoring in the Aso volcanic field. As a result, the gravity changes detected the hydrothermal flow in the subsurface which has a correlation to water level fluctuation in the crater. Large residual gravity changes between the surveys of absolute and relative gravimeter are found at benchmarks around Nakadake crater. Keywords: Microgravity monitoring, Aso volcanic field References [1] Battaglia, M., J. Gottsmann, D. Carbone, and J. Fernandez, 2008, 4D volcano gravimetry: Geophysics, vol. 73 no.6, p. WA3-WA18.

Sofyan, Yayan; Nishijima, Jun; Yoshikawa, Shin; Fujimitsu, Yasuhiro; Kagiyama, Tsuneomi; Fukuda, Yoichi

2014-05-01

372

Gravity and height measurements along the profile of Damavand mountain in Iran  

NASA Astrophysics Data System (ADS)

In order to model the earth gravity field, different gravity data with terrestrial, airborne and satellite gathered kinds are necessary. It is possible to recover by them the short, medium and long wavelengths of the gravity field respectively. Terrestrial gravity data, especially for the regions with highly variations, are useful for different purposes, i.e. to estimate the actual gravity range in the country, to extend the gravity calibration line, to study the isostasy status, to modify the numerical density models, to ameliorate the local geoid models, to prepare a background for geodynamical researches, and so on. Damavand, placed in central Alborz, is the highest mountain in Iran with the maximum elevation of 5610 meters. The region is considerable for its geodynamical activities with different active faults. Damavand had also some volcanic activities before. Sulphuric gases exit out now from different holes around the Damavand summit. A profile of 5 stations was established from down (1700 m) to the top of Damavand (5610 m). The height difference between each two neighbor stations is about 1000 meters. All the gravity differences between each 2 neighbor stations were measured by one CG-5 relative gravimeter in go and return manner to eliminate the instrumental drift error. The profile was connected to an absolute gravity station to ameliorate the qualities of the gravity results. The mentioned absolute gravity station is belong to the (Tele Cabin/ Land) National Gravity Calibration Line of Iran (TC/L NGCLI05) with a total gravity range of 1220 mGals. The modified total gravity range by this connection is 1650 mGals. All the stations of Damavand gravity profile were measured by a bi-frequency GPS receiver for a duration of 12 hours to obtain their precise geodetical heights with an accuracy of 1-3 cm (except one station at the summit, because of atmospheric limitations, only 1 hour GPS measurements obtained). The explained GPS campaign data were processed together with the simultaneous measurements of one permanent GPS station which placed 20 km far from Damavand mountain. Each 2 neighbor stations of Damavand gravity profile was trigonometrically levelled by a precise total station system, TC1800. The Damavand profile was also connected to the 1-st order national precise leveling network of Iran. An estimation of geoidal undulations was done along the profile by using the all three mentioned kinds of data.

Hatam Chavari, Y.; Djamour, Y.; Abolghasem, A. M.; Bayer, R.; Vanicek, P.

2009-04-01

373

Bubble Detachment in Variable Gravity Under the Influence of Electric Fields  

NASA Technical Reports Server (NTRS)

The objective of the research is to investigate the behavior of individual air bubbles injected through an orifice into an electrically insulating liquid under the influence of a static electric field. Situations were considered with both uniform and nonuniform electric fields. Bubble formation and detachment were visualized in terrestrial gravity as well as for several levels of reduced gravity (lunar, martian and microgravity) using a high-speed video camera. Bubble volume, dimensions and contact angles at detachment were measured. In addition to the experimental studies, a simple model, predicting bubble characteristics at detachment in an initially uniform electric field was developed. The model, based on thermodynamic considerations, accounts for the level of gravity as well as the magnitude of the uniform electric field. The results of the study indicate that the level of gravity and the electric field magnitude significantly affect bubble behavior as well as shape, volume and dimensions.

Herman, Cila; Chang, Shinan; Iacona, Estelle

2002-01-01

374

Gravity Virgins  

NASA Astrophysics Data System (ADS)

As an exercise in imagining a first encounter with gravity, let's begin with the barest gravitational circumstance. On a planet-sized spherical mass we find rigid poles extending to astronomical distances. At regular intervals along each pole there are Instrument Stations containing a clock, an accelerometer and light senders and receivers. Now imagine a civilization (the RC's) that has evolved in a huge self-sustaining Rotating Cylinder far removed from the sphere or any other astronomical body. The RC's are totally ignorant of gravity but understand well light propagation and the effect of motion on clocks, lengths, etc. Motion is sacred to the RC's because they know they'd die if their cylinder stopped rotating. Their clocks are synchronized so as to reflect the anisotropy of light sent in opposite directions along the cylinder's wall. When they set out to explore the Universe, they come upon the top of one of our tall poles. The RC's inspect the instruments, take data and leave their rocket off except when, in the nick of time, they turn it back on to navigate a soft landing. In their attempt to make sense of their experience, will they prefer a hypothesis resembling General Relativity or a hypothesis more like the one found at GravitationLab.com?

Benish, Richard

2008-05-01

375

Gravity change observed in a local gravity network and its implication to seasonal precipitation in Dali county, Yunnan province, China  

NASA Astrophysics Data System (ADS)

This study investigates data-processing methods and examines the precipitation effect on gravity measurements at the Dali gravity network, established in 2005. High-quality gravity data were collected during four measurement campaigns. To use the gravity data validly, some geophysical corrections must be considered carefully. We first discuss data-processing methods using weighted least-squares adjustment with the constraint of the absolute gravity datum. Results indicate that the gravity precision can be improved if all absolute gravity data are used as constraints and if calibration functions of relative gravimeters are modeled within the observation function. Using this data-processing scheme, the mean point gravity precision is better than 12 ?gal. After determining the best data-processing scheme, we then process the gravity data obtained in the four measurement campaigns, and obtain gravity changes in three time periods. Results show that the gravity has a remarkable change of more than 50 ?gal in the first time period from Apr-May of 2005 to Aug-Sept of 2007. To interpret the large gravity change, a mean water mass change (0.6 m in height) is assumed in the ETOPO1 topographic model. Calculations of the precipitation effect on gravity show that it can reach the same order of the observed gravity change. It is regarded as a main source of the remarkable gravity change in the Dali gravity network, suggesting that the precipitation effect on gravity measurements must be considered carefully.

Zhou, Xin; Sun, Wenke; Li, Hui; Okubo, Shuhei; Sun, Shaoan; Xing, Lelin; Liu, Dongzhi; Shen, Chongyang

2014-02-01

376

Gravity Within the Topographic Masses - Case Study Over Australia  

NASA Astrophysics Data System (ADS)

The behaviour of gravity within the topographic masses needs to be known for the determination of different gravity field parameters such as geoid height or orthometric height. For example, geoid determination by Stokes's formula requires downward continuation of gravity data to the geoid and the orthometric height is defined by the mean gravity along the plumb line between the Earth's surface and the geoid. In the past, different approximations (hypotheses for the topographic masses) have been used in order to derive gravity along the plumb line from the measured gravity at the Earth's surface. In this study a remove-restore technique based on the Poincaré and Prey reduction is used to determine gravity within the topographic masses. The actual free-air gradient in the reduced field is derived from the generalized Poisson's equation. From the gravity values given along the plumb line mean gravity as well as the mean gravity gradient are computed and compared with different (approximated) values used in the past. The results for mean gravity and the mean gravity gradient can be used in gravimetric geoid computation to realize an improved downward continuation as well as improved computation of orthometric heights from levelling and gravity measurements. Numerical results for mean gravity and the mean gravity gradient are given for two sample areas in Australia representing an area with a large range of topographic mass-density values and a mountainous area. Furthermore, the mean gravity values computed from different methods are used to estimate the effect on the orthometric height.

Kuhn, M.; Claessens, S.

2003-12-01

377

Gravity Wave Diagnosis Using Empirical Normal Modes.  

NASA Astrophysics Data System (ADS)

The theory of empirical normal modes (ENMs) is adapted to diagnose gravity waves generated by a relatively high-resolution numerical model solving the primitive equations. The ENM approach is based on the principal component analysis (which consists of finding the most efficient basis explaining the variance of a time series), except that it takes advantage of wave-activity conservation laws. In the present work, the small-amplitude version of the pseudoenergy is used to extract from data quasi-monochromatic three-dimensional empirical modes that describe atmospheric wave activity. The spatial distributions of these quasi-monochromatic modes are identical to the normal modes of the linearized primitive equations when the underlying dynamics can be described with a stochastic linear and forced model, thus establishing a bridge between statistics and dynamics. This diagnostic method is used to study inertia-gravity wave generation, propagation, transience, and breaking over the Rockies, the North Pacific, and Central America in the troposphere-stratosphere-mesosphere Geophysical Fluid Dynamics Laboratory SKYHI general circulation model at a resolution of 1° of latitude by 1.2° of longitude. Besides the action of mountains in exciting orographic waves, inertia-gravity wave activity has been found to be generated at the jet stream level as a possible consequence of a sustained nonlinear and ageostrophic flow. In the tropical region of the model (Central America), the inertia-gravity wave source mechanism produced mainly waves with a westward vertical tilt. A significant proportion of these inertia-gravity waves was able to reach the model mesosphere without much dissipation and absorption.

Charron, Martin; Brunet, Gilbert

1999-08-01

378

Satellite-to-satellite tracking and satellite gravity gradiometry (Advanced techniques for high-resolution geopotential field determination)  

Microsoft Academic Search

The purpose of satellite-to-satellite tracking (SST) and\\/or satellite gravity gradiometry (SGG) is to determine the gravitational field on and outside the Earth's surface from given gradients of the gravitational potential and\\/or the gravitational field at satellite altitude. In this paper both satellite techniques are analysed and characterized from a mathematical point of view. Uniqueness results are formulated. The justification is

Willi Freeden; Volker Michel; Helga Nutz

2002-01-01

379

[Kinetic theory and boundary conditions for flows of highly inelastic spheres: Application to gravity driven granular flows down bumpy inclines  

SciTech Connect

In this quarter, we extended our study of the effects of isotropic boundary vibrations to steady, gravity driven, inclined granular flows. These flows are more complex than those considered last quarter because of the presence of slip and mean velocity gradients at the boundary. Consequently, it was first necessary to modify the boundary conditions derived by Richman (1992) to account for corrections to the flow particle velocity distribution function from velocity gradients. In what follows we only summarize the results obtained.

Richman, M.W.

1992-01-01

380

Tides and gravity labs  

NSDL National Science Digital Library

How does gravity cause tides in the oceans? This section, part of an interactive laboratory series for grades 8-12, introduces students to four activities on tides and gravity that cover critical orbital speed between Earth and the moon, gravitational forces between two bodies, tidal effects from the sun and moon, and the change in tidal levels over time. The activities include hands-on animations of concepts whose variables can be manipulated by students. Questions posed to students include answer boxes that are printable upon conclusion of the activities. The final activity involves collecting tidal data over 24-hour and 29-day periods. Student data are stored in printable tables. Views of moon phases for each time period are provided, as is a downloadable worksheet. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2002-01-01

381

High pretransplantation soluble CD30 levels: impact in renal transplantation.  

PubMed

In a retrospective study, the impact of the level of pretransplantation soluble CD30 molecule (sCD30) was evaluated on 3 year transplant survival, as well as the number and grade of acute rejection episodes among kidney recipients engrafted between 2000 and 2002. One hundred and ninety sera of 190 patients sampled on the cross-match day were tested for sCD30 concentrations using an enzyme-linked immunosorbent assay (ELISA) kit (Biotest). For the analysis, a sCD30 cutoff level of 100 U/mL was chosen: 87 (46%) recipients had a level >100, and 103 (54%) <100. All cases (5) of immunological graft loss showed a high sCD30 level. The rate of biopsy-proven acute rejection was 26% in the sCD30 >100 group versus 22% in the sCD30 <100 groups. Among the first graft population (n = 157), the rate was 27% for sCD30 >100 versus 20% for the lower level. The difference was more important for grade II acute rejection (Banff criteria): 6/87 (7%) showed high sCD30 versus 2/103 (2%) with sCD30 <100. This analysis became significant for anti-HLA immunization: 11 (13%) recipients developed anti-HLA class II antibodies in the first group (sCD30 >100) versus 1 (1%) in the second group (sCD30 <100; P < .01). A high pretransplantation sCD30 was not a significant risk factor for an acute rejection episode, but it seemed to be more predictive for antibody-mediated acute rejection and immunological graft loss. However, many recipients showed an increased pretransplantation concentration without any rejection episode or graft loss. Consequently, sCD30 pregraft measurements cannot be used as a predictor for acute kidney rejection among our transplant center, nor as an aid to adapt the immunosuppressive regimen. PMID:17954178

Giannoli, C; Bonnet, M C; Perrat, G; Houillon, A; Reydet, S; Pouteil-Noble, C; Villar, E; Lefrançois, N; Morelon, E; Dubois, V

2007-10-01

382

High-level waste management technology program plan  

SciTech Connect

The purpose of this plan is to document the integrated technology program plan for the Savannah River Site (SRS) High-Level Waste (HLW) Management System. The mission of the SRS HLW System is to receive and store SRS high-level wastes in a see and environmentally sound, and to convert these wastes into forms suitable for final disposal. These final disposal forms are borosilicate glass to be sent to the Federal Repository, Saltstone grout to be disposed of on site, and treated waste water to be released to the environment via a permitted outfall. Thus, the technology development activities described herein are those activities required to enable successful accomplishment of this mission. The technology program is based on specific needs of the SRS HLW System and organized following the systems engineering level 3 functions. Technology needs for each level 3 function are listed as reference, enhancements, and alternatives. Finally, FY-95 funding, deliverables, and schedules are s in Chapter IV with details on the specific tasks that are funded in FY-95 provided in Appendix A. The information in this report represents the vision of activities as defined at the beginning of the fiscal year. Depending on emergent issues, funding changes, and other factors, programs and milestones may be adjusted during the fiscal year. The FY-95 SRS HLW technology program strongly emphasizes startup support for the Defense Waste Processing Facility and In-Tank Precipitation. Closure of technical issues associated with these operations has been given highest priority. Consequently, efforts on longer term enhancements and alternatives are receiving minimal funding. However, High-Level Waste Management is committed to participation in the national Radioactive Waste Tank Remediation Technology Focus Area. 4 refs., 5 figs., 9 tabs.

Harmon, H.D.

1995-01-01

383

DOE high-level waste tank safety program. Final report  

SciTech Connect

The overall objective of the work was to provide LANL with support to the DOE High-Level Waste Tank Safety Program. This effort included direct support to the DOE High-Level Waste Tank Working Groups, development of a database to track all identified safety issues, development of requirements for waste tank modernization, evaluation of external comments regarding safety-related guidance/instruction developed previously, examination of current federal and state regulations associated with DOE Tank farm operations, and performance of a conduct of operations review. All tasks which were assigned under this Task Order were completed. Descriptions of the objectives of each task and effort performed to complete each objective is provided.

NONE

1998-11-01

384

Review of High Level Waste Tanks Ultrasonic Inspection Data  

SciTech Connect

A review of the data collected during ultrasonic inspection of the Type I high level waste tanks has been completed. The data was analyzed for relevance to the possibility of vapor space corrosion and liquid/air interface corrosion. The review of the Type I tank UT inspection data has confirmed that the vapor space general corrosion is not an unusually aggressive phenomena and correlates well with predicted corrosion rates for steel exposed to bulk solution. The corrosion rates are seen to decrease with time as expected. The review of the temperature data did not reveal any obvious correlations between high temperatures and the occurrences of leaks. The complex nature of temperature-humidity interaction, particularly with respect to vapor corrosion requires further understanding to infer any correlation. The review of the waste level data also did not reveal any obvious correlations.

Wiersma, B

2006-03-09

385

Management of data quality of high level waste characterization  

SciTech Connect

Over the past 10 years, the Hanford Site has been transitioning from nuclear materials production to Site cleanup operations. High-level waste characterization at the Hanford Site provides data to support present waste processing operations, tank safety programs, and future waste disposal programs. Quality elements in the high-level waste characterization program will be presented by following a sample through the data quality objective, sampling, laboratory analysis and data review process. Transition from production to cleanup has resulted in changes in quality systems and program; the changes, as well as other issues in these quality programs, will be described. Laboratory assessment through quality control and performance evaluation programs will be described, and data assessments in the laboratory and final reporting in the tank characterization reports will be discussed.

Winters, W.I., Westinghouse Hanford

1996-06-12

386

RETENTION OF SULFATE IN HIGH LEVEL RADIOACTIVE WASTE GLASS  

SciTech Connect

High level radioactive wastes are being vitrified at the Savannah River Site for long term disposal. Many of the wastes contain sulfate at concentrations that can be difficult to retain in borosilicate glass. This study involves efforts to optimize the composition of a glass frit for combination with the waste to improve sulfate retention while meeting other process and product performance constraints. The fabrication and characterization of several series of simulated waste glasses are described. The experiments are detailed chronologically, to provide insight into part of the engineering studies used in developing frit compositions for an operating high level waste vitrification facility. The results lead to the recommendation of a specific frit composition and a concentration limit for sulfate in the glass for the next batch of sludge to be processed at Savannah River.

Fox, K.

2010-09-07

387

High-level vancomycin-resistant enterococci causing hospital infections.  

PubMed Central

Nosocomial infection or colonization due to enterococci with high-level resistance to vancomycin (minimal inhibitory concentrations [MICs] between 64 and greater than 2000 mg/L) has occurred in 41 patients with renal disease. These vancomycin-resistant enterococci were cultured from many sources including blood. All but one strain contained one or more plasmids ranging in molecular weight from 1.0 to 40 Megadaltons (MDa). Vancomycin resistance was transferable by conjugation to a susceptible recipient strain of Enterococcus faecalis but this was not always associated with plasmid DNA. The emergence of transferable high-level vancomycin resistance in enterococci causing significant clinical infections is of particular importance since vancomycin is widely regarded as a reserve drug for the management of infections with multi-resistant Gram-positive organisms.

Uttley, A. H.; George, R. C.; Naidoo, J.; Woodford, N.; Johnson, A. P.; Collins, C. H.; Morrison, D.; Gilfillan, A. J.; Fitch, L. E.; Heptonstall, J.

1989-01-01

388

The SuperSID project: exploiting high-level information for high-accuracy speaker recognition  

Microsoft Academic Search

The area of automatic speaker recognition has been dominated by systems using only short-term, low-level acoustic information, such as cepstral features. While these systems have indeed produced very low error rates, they ignore other levels of information beyond low-level acoustics that convey speaker information. Recently published work has shown examples that such high-level information can be used successfully in automatic

Douglas Reynolds; Walter Andrews; Joseph Campbell; Jiri Navratil; Barbara Peskin; Andre Adami; Qin Jin; David Klusacek; Joy Abramson; Radu Mihaescu; Jack Godfrey; Doug Jones; Bing Xiang

2003-01-01

389

Sound absorption of porous metals at high sound pressure levels.  

PubMed

This paper is a study about sound absorption properties of porous metals at high sound pressure levels. A method of deriving the nonlinear static flow resistance for highly porous fibrous metals is proposed by solving Oseen's equation to take account of the inertia effect, validated by experiments of airflow measurement. In order to predict nonlinear sound absorbing performance of a finite thickness porous metal layer, a numerical method is employed, verified by sound absorption measurement in an impedance tube. Accordingly, the effects of the nonlinear coefficient on the porous metal sound absorption are investigated. PMID:19640016

Wang, Xiaolin; Peng, Feng; Chang, Baojun

2009-08-01

390

Ionization chamber for measurements of high-level tritium gas  

SciTech Connect

The construction and calibration of a simple ionization-chamber apparatus for measurement of high level tritium gas is described. The apparatus uses an easily constructed but rugged chamber containing the unknown gas and an inexpensive digital multimeter for measuring the ion current. The equipment after calibration is suitable for measuring 0.01 to 100% tritium gas in hydrogen-helium mixes with an accuracy of a few percent. At both the high and low limits of measurements deviations from the predicted theoretical current are observed. These are briefly discussed.

Carstens, D.H.W.; David, W.R.

1980-01-01

391

Auto Detection For High Level Water Content For Oil Well  

NASA Astrophysics Data System (ADS)

Auto detection of high level water content for oil well is a system that measures the percentage of water in crude oil. This paper aims to discuss an auto detection system for measuring the content of water level in crude oil which is applicable for offshore and onshore oil operations. Data regarding water level content from wells can be determined by using automation thus, well with high water level can be determined immediately whether to be closed or not from operations. Theoretically the system measures the percentage of two- fluid mixture where the fluids have different electrical conductivities which are water and crude oil. The system made use of grid sensor which is a grid pattern like of horizontal and vertical wires. When water occupies the space at the intersection of vertical and horizontal wires, an electrical signal is detected which proved that water completed the circuit path in the system. The electrical signals are counted whereas the percentage of water is determined from the total electrical signals detected over electrical signals provided. Simulation of the system using the MultiSIM showed that the system provided the desired result.

Janier, Josefina Barnachea; Jumaludin, Zainul Arifin B.

2010-06-01

392

Quantum gravity and charge renormalization  

SciTech Connect

We study the question of the gauge dependence of the quantum gravity contribution to the running gauge coupling constant for electromagnetism. The calculations are performed using dimensional regularization in a manifestly gauge-invariant and gauge-condition-independent formulation of the effective action. It is shown that there is no quantum gravity contribution to the running charge, and hence there is no alteration to asymptotic freedom at high energies as predicted by Robinson and Wilczek.

Toms, David J. [School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

2007-08-15

393

An innovative cask for transporting defense high-level waste  

Microsoft Academic Search

In the early 1980s, the US Department of Energy\\/Defense Programs (DOE\\/DP) initiated a project to develop a safe and efficient transportation system for defense high-level waste (DHLW). Sandia National Laboratories (SNL) provides a technical oversight and test support and General Atomics provides the design and safety analysis of the shipping system. The specific activities include designing, testing, certifying and fabricating

F. P. Falci; G. C. Allen; M. M. Madsen; A. Zimmer; K. G. Golliher

1989-01-01

394

A High Level Architecture-based Medical Simulation System  

Microsoft Academic Search

This paper describes the Combat Trauma PatientSimulation (CTPS), with emphasis on how High LevelArchitecture (HLA) was used in its development. Thisintroductory section, which briefly reviews HLA andstates the objectives of the CTPS project, is followedby the two main sections of the paper. The first mainsection describes the functionality and components ofCTPS, and the second details how HLA supportedthat functionality. Future

Mikel D. Petty; Piotr S. Windyga

1999-01-01

395

Landau-Level Splitting in Graphene in High Magnetic Fields  

Microsoft Academic Search

The quantum Hall (QH) effect in two-dimensional electrons and holes in high quality graphene samples is studied in strong magnetic fields up to 45 T. QH plateaus at filling factors nu=0,±1,±4 are discovered at magnetic fields B>20T, indicating the lifting of the fourfold degeneracy of the previously observed QH states at nu=±4(|n|+1\\/2), where n is the Landau-level index. In particular,

Y. Zhang; Z. Jiang; J. P. Small; M. S. Purewal; Y.-W. Tan; M. Fazlollahi; J. D. Chudow; J. A. Jaszczak; H. L. Stormer; P. Kim

2006-01-01

396

High-Level Mixed-Mode System Simulation in VHDL  

Microsoft Academic Search

This work describes a set of VHDL packages high-level modelling and simulation of systems containing both discrete-time and continuous-time subsystems. The work was motivated by the need to model and simulate a robot control system. The discrete-time portion of the system is modelled as a set of concurrent processes communicating via several well-defined inter-process communication primitives that form a more

Mani B. Srivastava; Robert W. Brodersen

397

Mixing Processes in High-Level Waste Tanks - Final Report  

SciTech Connect

The mixing processes in large, complex enclosures using one-dimensional differential equations, with transport in free and wall jets is modeled using standard integral techniques. With this goal in mind, we have constructed a simple, computationally efficient numerical tool, the Berkeley Mechanistic Mixing Model, which can be used to predict the transient evolution of fuel and oxygen concentrations in DOE high-level waste tanks following loss of ventilation, and validate the model against a series of experiments.

Peterson, P.F.

1999-05-24

398

[Corrosion testing of high level radioactive waste. Final report  

SciTech Connect

Alloys under consideration as candidates for the high level nuclear waste containers at Yucca Mountain were exposed to a range of corrosion conditions and their performance measured. The alloys tested were Incoloy 825, 70/30 Copper-Nickel, Monel 400, Hastelloy C- 22, and low carbon steel. The test conditions varied were: temperature, concentration, agitation, and crevice simulation. Only in the case of carbon steel was significant attack noted. This attack appeared to be transport limited.

NONE

1996-06-01

399

Effective separation of palladium from simulated high level radioactive waste  

Microsoft Academic Search

Aiming the selective recovery of palladium from high level radioactive liquid waste (HLW), a chelating thiamide type sorbent,\\u000a CWP–TU, was prepared by the modification of Japanese cedar wood powder (CWP). Convection oven and microwave heating were separately\\u000a used for modification purpose and found that microwave heating is more effective over oven heating. CWP–TU was extensively\\u000a studied for the adsorption of

Durga Parajuli; Koichi Hirota; Noriaki Seko

2011-01-01

400

Security Mechanisms in High-Level Network Protocols  

Microsoft Academic Search

The implications of adding security mechanisms to high-level network protocols operating in an open-system environment are analyzed. First the threats to security that may arise in such an environment are described, and then a set of goals for communications security measures is established. This is followed by a brief description of the two basic approaches to communications security, link-oriented measures

Victor L. Voydock; Stephen T. Kent

1983-01-01

401

Using English as a High-Level Robot Command Language  

Microsoft Academic Search

To facilitate expedient communication with robots, a very high-level hierarchical robot command language (Hirob) has been designed and implemented. Hirob uses the full and comprehensive syntax of the English imperative, allowing users to control a robot without the need of learning an esoteric programming language. A Parser\\/Scanner\\/Recognizer (PSR) performs a lexical analysis of a Hirob command stream, and identifies which

Peter Bock

1983-01-01

402

Case for retrievable high-level nuclear waste disposal  

USGS Publications Warehouse

Plans for the nation's first high-level nuclear waste repository have called for permanently closing and sealing the repository soon after it is filled. However, the hydrologic environment of the proposed site at Yucca Mountain, Nevada, should allow the repository to be kept open and the waste retrievable indefinitely. This would allow direct monitoring of the repository and maintain the options for future generations to improve upon the disposal methods or use the uranium in the spent fuel as an energy resource.

Roseboom, Jr. , Eugene, H.

1994-01-01

403

High glucose levels enhance platelet activation: involvement of multiple mechanisms.  

PubMed

Diabetes mellitus (DM) and hyperglycaemia are associated with platelet activation. The present study was designed to investigate how high glucose levels influence platelet function. Fasting human blood was incubated with different concentrations of D-glucose (5, 15 and 30 mmol/l) and other sugars without or with in vitro stimuli. Platelet activation was monitored by whole blood flow cytometry. High glucose levels enhanced adenosine diphosphate (ADP)- and thrombin receptor-activating peptide (TRAP)-induced platelet P-selectin expression, and TRAP-induced platelet fibrinogen binding. Similar effects were seen with 30 mmol/l L-glucose, sucrose and galactose. Hyperglycaemia also increased TRAP-induced platelet-leucocyte aggregation. Protein kinase C (PKC) blockade did not counteract the enhancement of platelet P-selectin expression, but abolished the enhancement of TRAP-induced platelet fibrinogen binding by hyperglycaemia. Superoxide anion scavenging by superoxide dismutase (SOD) attenuated the hyperglycaemic enhancement of platelet P-selectin expression, but did not counteract the enhancement of TRAP-induced platelet fibrinogen binding. Hyperglycaemia did not alter platelet intracellular calcium responses to agonist stimulation. Blockade of cyclo-oxygenase (COX), phosphotidylinositol-3 (PI3) kinase, or nitric oxide synthase, or the addition of insulin did not influence the effect of hyperglycaemia. In conclusion, high glucose levels enhanced platelet reactivity to agonist stimulation through elevated osmolality. This occurred via superoxide anion production, which enhanced platelet P-selectin expression (secretion), and PKC signalling, which enhanced TRAP-induced fibrinogen binding (aggregablity). PMID:16643434

Sudic, Dzana; Razmara, Masoud; Forslund, Mikael; Ji, Qiushang; Hjemdahl, Paul; Li, Nailin

2006-05-01

404

Materials Science of High-Level Nuclear Waste Immobilization  

SciTech Connect

With the increasing demand for the development of more nuclear power comes the responsibility to address the technical challenges of immobilizing high-level nuclear wastes in stable solid forms for interim storage or disposition in geologic repositories. The immobilization of high-level nuclear wastes has been an active area of research and development for over 50 years. Borosilicate glasses and complex ceramic composites have been developed to meet many technical challenges and current needs, although regulatory issues, which vary widely from country to country, have yet to be resolved. Cooperative international programs to develop advanced proliferation-resistant nuclear technologies to close the nuclear fuel cycle and increase the efficiency of nuclear energy production might create new separation waste streams that could demand new concepts and materials for nuclear waste immobilization. This article reviews the current state-of-the-art understanding regarding the materials science of glasses and ceramics for the immobilization of high-level nuclear waste and excess nuclear materials and discusses approaches to address new waste streams.

Weber, William J.; Navrotsky, Alexandra; Stefanovsky, S. V.; Vance, E. R.; Vernaz, Etienne Y.

2009-01-09

405

High levels of IL-7 cause dysregulation of thymocyte development  

PubMed Central

IL-7 signaling is required for thymocyte development and its loss has a severe deleterious effect on thymus function. Thymocyte–stromal cell interactions and other mechanisms tightly regulate IL-7 expression. We show that disruption of that regulation by over-expression of IL-7 inhibits T-cell development and promotes extensive B-cell lymphopoiesis in the thymus. Our data reveal that high levels of IL-7 negate Notch-1 function in thymocytes found in IL-7 transgenic mice and in co-culture with OP9-DL1 cells. While high levels of IL-7R are present on thymocytes, increased suppressor of cytokine signaling-1 expression blunts IL-7 downstream signaling, resulting in hypo-phosphorylation of proteins in the PI3K-Akt pathway. Consequently, GSK3? remains active and inhibits Notch-1 signaling as observed by decreased Hes-1 and Deltex expression in thymic progenitors. This is the first demonstration that high levels of IL-7 antagonize Notch-1 signaling and suggest that IL-7 may affect T- versus B-lineage choice in the thymus.

El-Kassar, Nahed; Flomerfelt, Francis A.

2012-01-01

406

Handbook of high-level radioactive waste transportation  

SciTech Connect

The High-Level Radioactive Waste Transportation Handbook serves as a reference to which state officials and members of the general public may turn for information on radioactive waste transportation and on the federal government`s system for transporting this waste under the Civilian Radioactive Waste Management Program. The Handbook condenses and updates information contained in the Midwestern High-Level Radioactive Waste Transportation Primer. It is intended primarily to assist legislators who, in the future, may be called upon to enact legislation pertaining to the transportation of radioactive waste through their jurisdictions. The Handbook is divided into two sections. The first section places the federal government`s program for transporting radioactive waste in context. It provides background information on nuclear waste production in the United States and traces the emergence of federal policy for disposing of radioactive waste. The second section covers the history of radioactive waste transportation; summarizes major pieces of legislation pertaining to the transportation of radioactive waste; and provides an overview of the radioactive waste transportation program developed by the US Department of Energy (DOE). To supplement this information, a summary of pertinent federal and state legislation and a glossary of terms are included as appendices, as is a list of publications produced by the Midwestern Office of The Council of State Governments (CSG-MW) as part of the Midwestern High-Level Radioactive Waste Transportation Project.

Sattler, L.R.

1992-10-01

407

Topographic-Isostatic Reductions in Satellite Gravity Gradiometry Based on a Generalized Condensation Model  

Microsoft Academic Search

In satellite gravity gradiometry, the gravitational signals from the Earth’s topography and its isostatic compensation still exist in the gravity gradients observed along the satellite orbit. Due to the high-frequency behaviour of the combined topographic-isostatic effect, downward continuation of the gravitational signal from satellite height to sea level is rather difficult, requiring some mathematical method of regularization. On the other

B. Heck; F. Wild

408

Some interesting features of new massive gravity  

NASA Astrophysics Data System (ADS)

A sketch of a proof that new massive gravity—the massive 3D gravity model proposed by Bergshoeff, Hohm and Townsend (BHT)—is the only unitary system at the tree level that can be constructed by augmenting 3D general relativity through (curvature)2-terms is presented. Two interesting gravitational properties of the BHT model, namely, time dilation and time delay, which have no counterpart in the usual Einstein 3D gravity, are analyzed as well.

Accioly, Antonio; Helayël-Neto, José; Scatena, Eslley; Morais, Jefferson; Turcati, Rodrigo; Pereira-Dias, Bruno

2011-11-01

409

Laser welding in a reduced gravity environment  

NASA Technical Reports Server (NTRS)

Preliminary results on the effects of reduced gravity on laser welding of stainless steel and other materials are reported. Laser welding experiments using a low power (10-18 watts) Nd-YAG laser have been performed on the NASA KC-135, which flies parabolic maneuvers to simulate reduced gravity conditions. Experiments on 0.005-0.010 inch thick stainless steel samples displayed a pronounced change in weld bead width, depth of penetration and surface ripple with changes in gravity level.

Workman, Gary L.; Kaukler, William F.

1992-01-01

410

High-temperature leaching of an actinide-bearing, simulated high-level waste glass  

Microsoft Academic Search

The chemical durability of a simulated high-level waste glass when exposed to high-temperature geologic solutions was investigated. In this study, simulated high-level waste glass-beads (76 to 68 glass)l doped with technetium, uranium, neptunium, plutonium, curium and americium were leached in deionized water, Waste Isolation Pilot Plant salt brine B, and 0.03M sodium bicarbonate solution at 150 and 250°C for 2,

J. H. Jr. Westsik; C. O. Harvey; W. L. Kuhn

1983-01-01

411

Efficient automatic denoising of gravity gradiometry data  

Microsoft Academic Search

Gravity gradiometry data are prized for the high fre- quency information they provide. However, as any other geophysical data, gravity gradient measurements are contaminated by high-frequency noise. Separation of the high-frequency signal from noise is a crucial component of data processing. The separation can be performed in the frequency domain, which usually requires tuning fil- ter parameters at each survey

Julio Cesar; Soares de Oliveira Lyrio; Yaoguo Li

2004-01-01

412

Cellular basis of gravity resistance in plants  

NASA Astrophysics Data System (ADS)

Mechanical resistance to the gravitational force is a principal gravity response in plants distinct from gravitropism. In the final step of gravity resistance, plants increase the rigidity of their cell walls via modifications to the cell wall metabolism and apoplastic environment. We studied cellular events that are related to the cell wall changes under hypergravity conditions produced by centrifugation. Hypergravity induced reorientation of cortical microtubules from transverse to longitudinal directions in epidermal cells of stem organs. In Arabidopsis tubulin mutants, the percentage of cells with longitudinal microtubules was high even at 1 g, and it was further increased by hypergravity. Hypocotyls of tubulin mutants also showed either left-handed or right-handed helical growth at 1 g, and the degree of twisting phenotype was intensified under hypergravity conditions. The left-handed helical growth mutants had right-handed microtubule arrays, whereas the right-handed mutant had left-handed arrays. There was a close correlation between the alignment angle of epidermal cell files and the alignment of cortical microtubules. Gadolinium ions suppressed both the twisting phenotype and reorientation of microtubules in tubulin mutants. These results support the hypothesis that cortical microtubules play an es-sential role in maintenance of normal growth phenotype against the gravitational force, and suggest that mechanoreceptors are involved in modifications to morphology and orientation of microtubule arrays by hypergravity. Actin microfilaments, in addition to microtubules, may be involved in gravity resistance. The nucleus of epidermal cells of azuki bean epicotyls, which is present almost in the center of the cell at 1 g, was displaced to the cell bottom by increasing the magnitude of gravity. Cytochalasin D stimulated the sedimentation by hypergravity of the nu-cleus, suggesting that the positioning of the nucleus is regulated by actin microfilaments, which is affected by gravity. We also examined the effects of hypergravity on the osmotic properties of azuki bean epicotyls, and found that epicotyls were capable of maintaining osmoregulation even under hypergravity conditions at least for a short period. The increase in level of total osmotic solutes was suppressed by long-term hypergravity treatment, which was accounted by suppres-sion of translocation of organic solutes such as sugars and amino acids. These various cellular events may contribute to sustaining the cell wall changes or cooperate with the cell wall in gravity resistance. Space experiments on the International Space Station will confirm whether this view is applicable to plant resistance to 1 g gravity, as to the resistance to hypergravity.

Hoson, Takayuki; Matsumoto, Shouhei; Inui, Kenichi; Zhang, Yan; Soga, Kouichi; Wakabayashi, Kazuyuki; Hashimoto, Takashi

413

Threshold Gravity Determination and Artificial Gravity Studies Using Magnetic Levitation  

NASA Technical Reports Server (NTRS)

What is the threshold gravity (minimum gravity level) required for the nominal functioning of the human system? What dosage is required (magnitude and duration)? Do human cell lines behave differently in microgravity in response to an external stimulus? The critical need for a variable gravity simulator is emphasized by recent experiments on human epithelial cells and lymphocytes on the Space Shuttle clearly showing that cell growth and function are markedly different from those observed terrestrially. Those differences are also dramatic between cells grown in space and those in Rotating Wall Vessels (RWV), or NASA bioreactor often used to simulate microgravity, indicating that although morphological growth patterns (three dimensional growth) can be successfully simulated using RWVs, cell function performance is not reproduced - a critical difference. If cell function is dramatically affected by gravity off-loading, then cell response to stimuli such as radiation, stress, etc. can be very different from terrestrial cell lines. Yet, we have no good gravity simulator for use in study of these phenomena. This represents a profound shortcoming for countermeasures research. We postulate that we can use magnetic levitation of cells and tissue, through the use of strong magnetic fields and field gradients, as a terrestrial microgravity model to study human cells. Specific objectives of the research are: 1. To develop a tried, tested and benchmarked terrestrial microgravity model for cell culture studies; 2. Gravity threshold determination; 3. Dosage (magnitude and duration) of g-level required for nominal functioning of cells; 4. Comparisons of magnetic levitation model to other models such as RWV, hind limb suspension, etc. and 5. Cellular response to reduced gravity levels of Moon and Mars.

Ramachandran, N.; Leslie, F.

2005-01-01

414

Radiative Lifetimes for High Levels of Neutral Fe  

NASA Astrophysics Data System (ADS)

New radiative lifetime measurements for ~ 50 high lying levels of Fe I are reported. Laboratory astrophysics faces a challenge to provide basic spectroscopic data, especially reliable atomic transition probabilities, in the IR region for abundance studies. The availability of HgCdTe (HAWAII) detector arrays has opened IR spectral regions for extensive new spectroscopic studies. The SDSS III APOGEE project in the H-Band is an important example which will penetrate the dust obscuring the Galactic bulge. APOGEE will survey elemental abundances of 100,000 red giant stars in the bulge, bar, disk, and halo of the Milky Way. Many stellar spectra in the H-Band are, as expected, dominated by transitions of Fe I. Most of these IR transitions connect high levels of Fe. Our program has started an effort to meet this challenge with new radiative lifetime measurements on high lying levels of Fe I using time resolved laser induced fluorescence (TRLIF). The TRLIF method is typically accurate to 5% and is efficient. Our goal is to combine these accurate, absolute radiative lifetimes with emission branching fractions [1] to determine log(gf) values of the highest quality for Fe I lines in the UV, visible, and IR. This method was used very successfully by O’Brian et al. [2] on lower levels of Fe I. This method is still the best available for all but very simple spectra for which ab-initio theory is more accurate. Supported by NSF grant AST-0907732. [1] Branching fractions are being measured by M. Ruffoni and J. C. Pickering at Imperial College London. [2] O'Brian, T. R., Wickliffe, M. E., Lawler, J. E., Whaling, W., & Brault, J. W. 1991, J. Opt. Soc. Am. B 8, 1185

Lawler, James E.; Den Hartog, E.; Guzman, A.

2013-01-01

415

Proof of concept and performance optimization of high gravity batch-type centrifugal dryer for dewatering fine coal. Final report, September 20, 1989--September 21, 1991  

SciTech Connect

The primary objective of the project was to assemble, analyze and make use of those data that could help to clearly identify, optimize and confirm the technical and economic advantages that the new high gravity centrifugal dryer technology can provide to the coal industry and to end users. Other objectives were: to confirm the feasibility of the dryer for drying coals from a number of different seams; to use the data base for optimizing the dryer`s systems, and: to produce projected technical and economic comparisons with thermal dryers as applied to an existing coal processing plant flow sheet. (JL)

Smith, L.B.; Durney, T.

1991-12-31

416

Permitting plan for the high-level waste interim storage  

SciTech Connect

This document addresses the environmental permitting requirements for the transportation and interim storage of solidified high-level waste (HLW) produced during Phase 1 of the Hanford Site privatization effort. Solidified HLW consists of canisters containing vitrified HLW (glass) and containers that hold cesium separated during low-level waste pretreatment. The glass canisters and cesium containers will be transported to the Canister Storage Building (CSB) in a U.S. Department of Energy (DOE)-provided transportation cask via diesel-powered tractor trailer. Tri-Party Agreement (TPA) Milestone M-90 establishes a new major milestone, and associated interim milestones and target dates, governing acquisition and/or modification of facilities necessary for: (1) interim storage of Tank Waste Remediation Systems (TWRS) immobilized HLW (IHLW) and other canistered high-level waste forms; and (2) interim storage and disposal of TWRS immobilized low-activity tank waste (ILAW). An environmental requirements checklist and narrative was developed to identify the permitting path forward for the HLW interim storage (HLWIS) project (See Appendix B). This permitting plan will follow the permitting logic developed in that checklist.

Deffenbaugh, M.L.

1997-04-23

417

Gravity Behaves Like That?  

NASA Astrophysics Data System (ADS)

Many concepts of chaotic action in astrodynamics can be appreciated through simulations with home computers and software. Many astrodynamical cases are illustrated. Although chaos theory is now applied to spaceflight trajectories, this presentation employs only inert bodies with no onboard impulse, e.g., from rockets or outgassing. Other nongravitational effects are also ignored, such as atmosphere drag, solar pressure, and radiation. The ability to simulate gravity behavior, even if not completely rigorous, on small mass-market computers allows a fuller understanding of the new approach to astrodynamics by home astronomers, scientists outside orbital mechanics, and students in middle and high school. The simulations can also help a lay audience visualize gravity behavior during press conferences, briefings, and public lectures. No review, evaluation, critique of the programs shown in this presentation is intended. The results from these simulations are not valid for - and must not be used for - making earth-colliding predictions.

Pazmino, John

2007-02-01

418

Granular Superconductors and Gravity  

NASA Technical Reports Server (NTRS)

As a Bose condensate, superconductors provide novel conditions for revisiting previously proposed couplings between electromagnetism and gravity. Strong variations in Cooper pair density, large conductivity and low magnetic permeability define superconductive and degenerate condensates without the traditional density limits imposed by the Fermi energy (approx. 10(exp -6) g cu cm). Recent experiments have reported anomalous weight loss for a test mass suspended above a rotating Type II, YBCO superconductor, with a relatively high percentage change (0.05-2.1%) independent of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 104 was reported above a stationary (non-rotating) superconductor. In experiments using a sensitive gravimeter, bulk YBCO superconductors were stably levitated in a DC magnetic field and exposed without levitation to low-field strength AC magnetic fields. Changes in observed gravity signals were measured to be less than 2 parts in 108 of the normal gravitational acceleration. Given the high sensitivity of the test, future work will examine variants on the basic magnetic behavior of granular superconductors, with particular focus on quantifying their proposed importance to gravity.

Noever, David; Koczor, Ron

1999-01-01

419

Alternate methods for high level pyrotechnic shock simulation  

NASA Astrophysics Data System (ADS)

Two effective methods to recreate a realistic pyrotechnic shock are presented. The first method employs a resonant beam and is used for SRS levels of 12,000 G or more. The test unit is at one end of the beam and a hammer strikes the opposite end causing a shock to be transmitted to the other end of the fixture. The second method is based on a standard shaker system with a resonant beam to amplify the input signal. The engineer defines the duration of the shock signal induced to the vibration amplifier using the GenRad 2514 controller. The shock signal is then input via the shaker to the resonant beam, which amplifies the signal to produce the desired response at the end of the fixture. The shock response spectrum stays within a +/-6 dB tolerance with levels as high as 3000 G peak. These methods are repeatable, reliable, cost-effective, and consistent with a real pyroevent.

Gray, Phillip J., Sr.

420

High levels of ?-tocopherol in Norwegian alpine grazing plants.  

PubMed

Antioxidants prevent oxidation of fatty acids in milk and meat. In the present study, the content of tocopherol antioxidants (vitamin E) in vegetative and reproductive parts of 22 grazing plants was estimated in two alpine areas used for summer farming. The overall mean content of ?-tocopherol was 135 ± 34 ?g g(-1) DW, and grasses had much lower content (28 ± 11 ?g g(-1) DW) than herbs (215 ± 94 ?g g(-1) DW), sedges (186 ± 78 ?g g(-1) DW), and woody species (178 ± 52 ?g g(-1) DW). Highest and lowest species-specific levels were 649 ± 91 and 2 ± 1 ?g g(-1) DW, respectively. Plants from light and shady habitats did not differ in their ?-tocopherol content, which was idiosyncratic as indicated by significant interactions between species, sampling occasion, site, and tissue type. Our results show that alpine ranges provide fodder with high levels of ?-tocopherol. PMID:22775115

Sickel, Hanne; Bilger, Wolfgang; Ohlson, Mikael

2012-08-01

421

University-Level Research Projects for High School Students  

NASA Technical Reports Server (NTRS)

The goal of this project was to provide an opportunity for high school students to participate in university-level research projects. In this case, students from Pinkerton Academy (Derry, New Hampshire) were invited to participate in efforts to catalog data from the COMPTEL experiment on NASA's Compton Gamma-Ray Observatory (CGRO). These activities were part of a senior level honors course at Pinkerton. Although the success of this particular program was rather limited, we feel that the general concept is a sound one. In principle, the concept of partnerships between local schools and university researchers is one that could be especially attractive to soft money researchers. Programs can be carefully designed to benefit both the students and the research program.

McConnell, Mark L.

2000-01-01

422

Effects of high vs low-level radiation exposure  

SciTech Connect

In order to appreciate adequately the various possible effects of radiation, particularly from high-level vs low-level radiation exposure (HLRE, vs LLRE), it is necessary to understand the substantial differences between (a) exposure as used in exposure-incidence curves, which are always initially linear and without threshold, and (b) dose as used in dose-response curves, which always have a threshold, above which the function is curvilinear with increasing slope. The differences are discussed first in terms of generally familiar nonradiation situations involving dose vs exposure, and then specifically in terms of exposure to radiation, vs a dose of radiation. Examples are given of relevant biomedical findings illustrating that, while dose can be used with HLRE, it is inappropriate and misleading the LLRE where exposure is the conceptually correct measure of the amount of radiation involved.

Bond, V.P.

1983-01-01

423

Approaches to Quantum Gravity  

NASA Astrophysics Data System (ADS)

Preface; Part I. Fundamental Ideas and General Formalisms: 1. Unfinished revolution C. Rovelli; 2. The fundamental nature of space and time G. 't Hooft; 3. Does locality fail at intermediate length scales R. Sorkin; 4. Prolegomena to any future quantum gravity J. Stachel; 5. Spacetime symmetries in histories canonical gravity N. Savvidou; 6. Categorical geometry and the mathematical foundations of quantum gravity L. Crane; 7. Emergent relativity O. Dreyer; 8. Asymptotic safety R. Percacci; 9. New directions in background independent quantum gravity F. Markopoulou; Questions and answers; Part II: 10. Gauge/gravity duality G. Horowitz and J. Polchinski; 11. String theory, holography and quantum gravity T. Banks; 12. String field theory W. Taylor; Questions and answers; Part III: 13. Loop Quantum Gravity T. Thiemann; 14. Covariant loop quantum gravity? E. LIvine; 15. The spin foam representation of loop quantum gravity A. Perez; 16. 3-dimensional spin foam quantum gravity L. Freidel; 17. The group field theory approach to quantum gravity D. Oriti; Questions and answers; Part IV. Discrete Quantum Gravity: 18. Quantum gravity: the art of building spacetime J. Ambjørn, J. Jurkiewicz and R. Loll; 19. Quantum Regge calculations R. Williams; 20. Consistent discretizations as a road to quantum gravity R. Gambini and J. Pullin; 21. The causal set approach to quantum gravity J. Henson; Questions and answers; Part V. Effective Models and Quantum Gravity Phenomenology: 22. Quantum gravity phenomenology G. Amelino-Camelia; 23. Quantum gravity and precision tests C. Burgess; 24. Algebraic approach