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1

Groundwater recharge in natural dune systems and agricultural ecosystems in the Thar Desert region, Rajasthan, India  

NASA Astrophysics Data System (ADS)

Water and nutrient availability for crop production are critical issues in (semi)arid regions. Unsaturated-zone Cl tracer data and nutrient (NO3 and PO4) concentrations were used to quantify recharge rates using the Cl mass balance approach and nutrient availability in the Thar Desert, Rajasthan, India. Soil cores were collected in dune/interdune settings in the arid Thar Desert (near Jaisalmer) and in rain-fed (nonirrigated) and irrigated cropland in the semiarid desert margin (near Jaipur). Recharge rates were also simulated using unsaturated zone modeling. Recharge rates in sparsely vegetated dune/interdune settings in the Jaisalmer study area are 2.7-5.6 mm/year (2-3% of precipitation, 165 mm/year). In contrast, recharge rates in rain-fed agriculture in the Jaipur study area are 61-94 mm/year (10-16% of precipitation, 600 mm/year). Minimum recharge rates under current freshwater irrigated sites are 50-120 mm/year (8-20% of precipitation). Nitrate concentrations are low at most sites. Similarity in recharge rates based on SO4 with those based on Cl is attributed to a meteoric origin of SO4 and generally conservative chemical behavior in these sandy soils. Modeling results increased confidence in tracer-based recharge estimates. Recharge rates under rain-fed agriculture indicate that irrigation of 20-40% of cultivated land with 300 mm/year should be sustainable.

Scanlon, Bridget R.; Mukherjee, Abhijit; Gates, John; Reedy, Robert C.; Sinha, Amarendra K.

2010-06-01

2

Groundwater recharge in natural dune systems and agricultural ecosystems in the Thar Desert region, Rajasthan, India  

Microsoft Academic Search

Water and nutrient availability for crop production are critical issues in (semi)arid regions. Unsaturated-zone Cl tracer\\u000a data and nutrient (NO3 and PO4) concentrations were used to quantify recharge rates using the Cl mass balance approach and nutrient availability in the\\u000a Thar Desert, Rajasthan, India. Soil cores were collected in dune\\/interdune settings in the arid Thar Desert (near Jaisalmer)\\u000a and in

Bridget R. Scanlon; Abhijit Mukherjee; John Gates; Robert C. Reedy; Amarendra K. Sinha

2010-01-01

3

Recharge  

SciTech Connect

This chapter describes briefly the nature and measurement of recharge in support of the CH2M HILL Tank Farm Vadose Zone Project. Appendix C (Recharge) and the Recharge Data Package (Fayer and Keller 2007) provide a more thorough and extensive review of the recharge process and the estimation of recharge rates for the forthcoming RCRA Facility Investigation report for Hanford single-shell tank (SST) Waste Management Areas (WMAs).

Fayer, Michael J.

2008-01-17

4

Sand Dunes  

NSDL National Science Digital Library

Most will agree that nothing is more relaxing that lying or walking on a beach. While unwinding, have you ever wondered what caused those big mounds of sand that you crossed to get there? This topic in depth addresses this issue, featuring Web sites that discuss sand dune processes and formations. Some of the Web sites also discuss research, mining, and protection activities taking place in areas with sand dune.The Environment Bay of Plenty in New Zealand has an online brochure (1) dealing with the coastal processes that form sand dunes and beaches. From this site, users can obtain a general understanding of how dunes change with time. Ted Brambleby developed the second site (2) for the Marine Education Society of Australasia, Inc. This site gives a great overview of the functions and formations of dunes as well as describing their unique beauty and strategies on how to care for the dunes. Produced by Nova Scotia Museum of Natural History, the third site (3) is an online pamphlet discussing the physical features and locations of sand dunes in Nova Scotia. Visitors can also read about the ecosystem supported by these dynamic features. The forth site (4), created by John Mangimeli for the National Park Service, is a review of the scientific research completed throughout the years dealing with the geology of sand dunes. Visitors will find a more in-depth discussion about sand movement, sand accumulation, and sand dune features. The fifth site is a scientific paper (5 ) written by R.L. Van Dam, et al. Studying the long term evolution of the Parengarenga Sandspit, these researchers used ground penetrating radar (GPR) "to (1) explore the possibilities for mapping lateral continuity of the coffee rock, (2) study the sedimentary architecture and stratigraphy of the solitary dunes, and (3) reconstruct the wind regime on the sandspit." The next two sites discuss the threats to sand dunes and activities taking place to protect them. The Lake Michigan Federation addresses the issues of mining (6). Visitors can learn about alternatives to mining dune sand and the ecological values of dunes. The Department of Environmental Quality in Michigan created a site (7) that provides users with statistical information dealing with the amount of sand harvested, the regulations of mining, and maps of critical dune areas. After learning about the formation, processes, threats, and protections efforts; the last site (8), created by Eva Hornecker with the University of Bremen, will allow users to get a real sense of the beauty of the sand dunes. The site features a collage of spectacular images of the Great Sand Dunes in the San Luis Valley.

Enright, Rachel

5

Dune Geomorphology  

NSDL National Science Digital Library

This activity was developed during the workshop, Teaching Climate Change: Insight from Large Lakes, held in June 2012. Dune Geomorphology by Anthony (Tony) Layzell, University of Kansas Main Campus J. Elmo ...

6

Dune Formation  

Microsoft Academic Search

Dunes are ubiquitous and exist in many forms in deserts and along coasts. They are a consequence of the wind moving sand grains\\u000a by a mechanism called “saltation”. In order to describe the formation and evolution of dunes one must understand the surface\\u000a flux of sand. Using the equation of motion of turbulent air in the approximation of Jackson and

Hans J. Herrmann

7

Evaluation of scraping treatments to restore initial infiltration capacity of three artificial recharge projects in central Iran  

NASA Astrophysics Data System (ADS)

A limiting factor in developing artificial recharge of groundwater is clogging of the soil surface and consequent reduction of infiltration rates. In order to evaluate the degree of improving infiltration rates by scraping away various amounts of the upper soil materials, a study was conducted at three artificial recharge sites (Kohrouyeh, Bagh-Sorkh, and Kachak) in Isfahan Province, central Iran. Five treatments (T1-T5) were considered. Infiltration was measured: T1, on deposited sediment layer; T2, after removing the sediments; T3, scraping of sediments and 5cm of soil; T4, scraping of sediments and 10cm of soil; and T5, removing sediments and 15cm of soil. Initial soil-moisture content of the sites ranged from 1.0-2.87% for Kohrouyeh, 1.18-3.47% for Bagh-Sorkh, and 1.89-3.93% for Kachak. The main texture of the soils was sandy loam. Clay particles have penetrated to a depth of more than 40cm in some of the recharge basins. A significant increase in final infiltration rate of T5 as compared to T1 treatment was observed for all recharge sites. The final infiltration rates of T1 and T5 treatments for Kohrouyeh, Bagh-Sorkh, and Kachak sites were 0.35, 7.9; 1.22, 12.3; and 0.93, 6.2cm/h, respectively. The differences between infiltration rates of T2, T3, and T4 treatments were not statistically significant. It is concluded that on average, the infiltration capacity of the untreated recharge facilities have reached 20.3% of the original values, and that scraping the top sediment layer and 15cm of topsoil could restore 68.3% of the initial infiltration capacity. Résumé Un facteur limitant lorsqu'on développe la recharge artificielle d'une nappe est le colmatage de la surface du sol et la réduction concomitante des taux d'infiltration. Afin d'évaluer le degré d'amélioration de l'infiltration en grattant de différentes manières la surface du sol, une étude a été conduite sur trois sites de recharge artificielle (Kohrouyeh, Bagh-Sorkh et Kachak) dans la province d'Ispahan (Iran central). Cinq traitements (T1-T5) ont été testés et l'infiltration a été mesurée: T1, sur une couche de sédiments déposés T2, après enlèvement du sédiment T3, grattage des sédiments et du sol sur 5cm T4, grattage des sédiments et du sol sur 10cm et T5, enlèvement des sédiments et de 15cm de sol. La teneur initiale en eau du sol sur les sites va de 1.0 à 2.87% à Kohrouyeh, 1.18 à 3.47% à Bagh-Sorkh, et 1.89 à 3.93% à Kachak. Les sols sonbt surtout des sols végétaux sableux. Les particules argileuses ont pénétré jusqu'à plus de >40cm de profondeur dans certains bassins de recharge. Un accroissement significatif du taux final d'infiltration de la procédure T5 comparée à T1 a été observée sur tous les sites de recharge. Les taux finaux d'infiltration des procédures T1 et T5 à Kohrouyeh, Bagh-Sorkh et Kachak étaient respectivement 0.35 et 7.9, 1.22 et 12.3, et 0.93 et 6.2cm/h. Les taux d'infiltration des procédures T2, T3 et T4 ne présentaient pas statistiquement de différences significatives. On en conclut donc qu'en moyenne la capacité d'infiltration de la recharge non traitée s'est accrue de 20.3 % par rapport aux valeurs initiales, et que le grattage du sommet du sédiment et du sol sur 15cm peut améliorer 68.3 % de la capacité initiale d'infiltration.

Mousavi, Sayed-Farhad; Rezai, Vafa

8

Choosing appropriate techniques for quantifying groundwater recharge  

NASA Astrophysics Data System (ADS)

Various techniques are available to quantify recharge; however, choosing appropriate techniques is often difficult. Important considerations in choosing a technique include space/time scales, range, and reliability of recharge estimates based on different techniques; other factors may limit the application of particular techniques. The goal of the recharge study is important because it may dictate the required space/time scales of the recharge estimates. Typical study goals include water-resource evaluation, which requires information on recharge over large spatial scales and on decadal time scales; and evaluation of aquifer vulnerability to contamination, which requires detailed information on spatial variability and preferential flow. The range of recharge rates that can be estimated using different approaches should be matched to expected recharge rates at a site. The reliability of recharge estimates using different techniques is variable. Techniques based on surface-water and unsaturated-zone data provide estimates of potential recharge, whereas those based on groundwater data generally provide estimates of actual recharge. Uncertainties in each approach to estimating recharge underscore the need for application of multiple techniques to increase reliability of recharge estimates. Résumé. Il existe différentes techniques pour quantifier la recharge; toutefois, il est souvent difficile de choisir les techniques appropriées. Les points importants pour le choix d'une technique sont l'échelle de temps et d'espace, la gamme de valeurs et la validité des estimations de la recharge basées sur différentes techniques; d'autres facteurs peuvent limiter l'application de techniques particulières. Le but des études de la recharge est important parce qu'il peut imposer les échelles de temps et d'espace des estimations de recharge. Les buts de ces études concernent habituellement l'évaluation des ressources en eau, qui requiert des informations sur la recharge à des échelles spatiales étendues et sur des durées comptées en dizaines d'années, et l'évaluation de la vulnérabilité des aquifères aux contaminations, qui exige des informations détaillées sur la variabilité spatiale et les écoulements préférentiels. La gamme des taux de recharge qui peuvent être estimés par différentes approches doit être adaptée aux valeurs attendues de la recharge sur le site. La validité des estimations de recharge faites par des techniques différentes est variable. Des techniques s'appuyant sur des données concernant les eaux de surface et la zone non saturée fournissent des estimations de recharge potentielle, tandis que celles basées sur les données des eaux souterraines donnent généralement des estimations de la recharge réelle. Les incertitudes de chaque approche d'estimation de la recharge mettent en relief la nécessité d'appliquer des techniques multiples pour accroître la validité des estimations de la recharge. Resumen. Existen diversas técnicas para cuantificar la recarga, pero elegir las apropiadas es a menudo difícil. Entre las consideraciones a tener en cuenta, hay que citar las escalas espacial y temporal, el rango y la fiabilidad de las estimaciones de la recarga obtenidas por medio de técnicas diferentes; hay otros factores que pueden limitar la aplicación de técnicas particulares. El objetivo de un estudio de recarga es importante, ya que puede condicionar las escalas temporal y espacial de las estimaciones. Los objetivos típicos comprenden la evaluación de recursos, cosa que requiere información de la recarga para escalas espaciales extensas y escalas temporales cifradas en décadas, y la evaluación de la vulnerabilidad del acuífero a la contaminación, para lo que hace falta información detallada sobre la variabilidad espacial y el flujo preferente. Se debería contrastar el rango de los valores estimados de recarga mediante enfoques diferentes con los valores esperados en un emplazamiento. La fiabilidad de las estimaciones basadas en técnicas diferentes es variable. Así, la

Scanlon, Bridget; Healy, Richard; Cook, Peter

2002-01-01

9

Morphodynamics of star dunes  

NASA Astrophysics Data System (ADS)

Star dunes are among the biggest and the most impressive dunes in Earth sand seas. Nonetheless, they remain poorly studied, probably because of their apparent complexity. They are massive pyramidal dunes with interlaced arms whose slip faces are oriented in various directions. Being large, they can integrate wind properties over a wide range of time scales. Thus, they are observed for wind regimes with multiple directions, and may result from the amalgamation of dunes or from the development of arms on a well-established dune pattern. In both cases, the roles of wind directional variability and secondary flow have been emphasized but not precisely quantified. Here, we report simulations where the star dune shape results from a a combination of longitudinal dunes, which form the star dune arms. These arms may radiate and so interact with the other dunes in the field. This mass exchange, controlled by the morphodynamics of star dunes arms, must play an important role in the large-scale arrangement of star dunes networks. We first demonstrate that star dune arms orientation maximizes the flux in the direction of crests. This is opposed to the usually admit dunes orientation, which maximizes the sediment transport perpendicular to the crest. Indeed, depending on sand availability, dunes development results from the growth of a wave on a sand bed or from a net transport of sediment, which grows and extends an isolated longitudinal dune over a non-erodible soil. These two different mechanisms lead to two different modes of crests orientation. Then, we show that the propagating arms reach a stationary state characterized by constant width, height and growth rate. These are controlled by the frequency at which the wind changes direction. Arm width and height increase, whereas the propagation speed decreases with a decreasing frequency. These morphodynamics properties are helpful to assess from pattern observation the variability of wind directionality over several time scales.

Zhang, D.; Narteau, C.; Rozier, O.; Courrech du Pont, S.

2012-04-01

10

Portable photovoltaic battery recharger  

Microsoft Academic Search

A portable photovoltaic battery recharger is described for simultaneously recharging a plurality of rechargeable batteries having different sizes and respective optimum charging current levels, comprising: a plurality of photovoltaic solar cell arrays corresponding to the number of different battery sizes, each of the cell arrays having a plurality of individual solar cells, each cell of a respective array having a

A. M. Ricaud; F. Artigliere

1989-01-01

11

Column experiments to study nonlinear removal of bacteriophages by passage through saturated dune sand  

Microsoft Academic Search

In a recent field study on dune recharge, bacteriophages MS2 and PRD1 were found to be removed 3 log10 over the first 2.4 m and only 5 log10 over the next 27 m. To understand the causes of this nonlinear removal, column experiments were carried out under conditions similar to the field: same recharge water, temperature (5±3 °C) and pore

J. F. Schijven; S. M. Hassanizadeh; H. A. M. de Bruin

2002-01-01

12

Booming Sand Dunes  

NASA Astrophysics Data System (ADS)

"Booming" sand dunes are able to produce low-frequency sound that resembles a pure note from a music instrument. The sound has a dominant audible frequency (70-105 Hz) and several higher harmonics and may be heard from far distances away. A natural or induced avalanche from a slip face of the booming dune triggers the emission that may last for several minutes. There are various references in travel literature to the phenomenon, but to date no scientific explanation covered all field observations. This thesis introduces a new physical model that describes the phenomenon of booming dunes. The waveguide model explains the selection of the booming frequency and the amplification of the sound in terms of constructive interference in a confined geometry. The frequency of the booming is a direct function of the dimensions and velocities in the waveguide. The higher harmonics are related to the higher modes of propagation in the waveguide. The experimental validation includes quantitative field research at the booming dunes of the Mojave Desert and Death Valley National Park. Microphone and geophone recordings of the acoustic and seismic emission show a variation of booming frequency in space and time. The analysis of the sensor data quantifies wave propagation characteristics such as speed, dispersion, and nonlinear effects and allows the distinction between the source mechanism of the booming and the booming itself. The migration of sand dunes results from a complicated interplay between dune building, wind regime, and precipitation. The morphological and morphodynamical characteristics of two field locations are analyzed with various geophysical techniques. Ground-penetrating radar images the subsurface structure of the dunes and reveal a natural, internal layering that is directly related to the history of dune migration. The seismic velocity increases abruptly with depth and gradually increases with downhill position due to compaction. Sand sampling shows local cementation of sand grains within the discrete layers that explains the increase in velocity and decrease in porosity. The subsurface layering may influence the speed of dune migration and therefore have important consequences on desertification. The positive qualitative and quantitative correlation between the subsurface layering in the dune and the manifestation of the booming sound implies a close relation between environmental factors and the booming emission. In this thesis, the frequency of booming is correlated with the depth of the waveguide and the seismic velocities. The variability on location and season suggests that the waveguide theory successfully unravels the phenomenon of booming sand dunes.

Vriend, Nathalie

13

Numerical modeling groundwater recharge and its implication in water cycles of two interdunal valleys in the Sand Hills of Nebraska  

NASA Astrophysics Data System (ADS)

The topography and geomorphology of the sand dunes and interdunal valleys in the Nebraska Sand Hills play important roles in regional water cycle by influencing groundwater recharge and evapotranspiration (ET). In this study, groundwater recharge, associated with precipitation and ET as well as soil hydraulics, and its spatial variations owing to the topography of dunes and valleys are examined. A method is developed to describe the recharge as a function of the storage capacity of dunes of various heights. After the method is tested using observations from a network of wells in the Sand Hills, it is used in the MODFLOW model to simulate and describe recharge effects on groundwater table depth at two different dune-valley sites. Analysis of modeled groundwater budget shows that the groundwater table depth in the interdunal valleys is critically influenced by vertical groundwater flows from surrounding dunes. At the site of higher dunes there are steadier and larger vertical groundwater flows in the dunes from their previous storage of precipitation. These vertical flows change to be horizontal converging groundwater flows and create upwelling in the interdunal valleys, where larger ET loss at the surface further enhances groundwater upwelling. Such interdunal valley is the major concentration area of the surface water and groundwater flow in the Sand Hills. At the site of shallow dunes and a broad interdunal valley the supply of groundwater from the dunes is trivial and inadequate to support upwelling of groundwater in the valley. The groundwater flows downward in the valley, and the valley surface is dry. Weak ET loss at the surface has a smaller effect on the groundwater storage than the precipitation recharge, making such area a source for groundwater.

Chen, Xi; Huang, Yuanyang; Ling, Minhua; Hu, Qi; Liu, Bo

14

Sand dunes as migrating strings.  

PubMed

We develop a reduced complexity model for three-dimensional sand dunes, based on a simplified description of the longitudinal and lateral sand transport. The spatiotemporal evolution of a dune migrating over a nonerodible bed under unidirectional wind is reduced to the dynamics of its crest line, providing a simple framework for the investigation of three-dimensional dunes, such as barchan and transverse dunes. Within this model, we derive analytical solutions for barchan dunes and investigate the stability of a rectilinear transverse dune against lateral fluctuations. We show, in particular, that the latter is unstable only if the lateral transport on the dune slip face prevails over that on the upwind face. We also predict the wavelength and the characteristic time that control the subsequent evolution of an unstable transverse dune into a wavy ridge and the ultimate fragmentation into barchan dunes. PMID:23767529

Guignier, L; Niiya, H; Nishimori, H; Lague, D; Valance, A

2013-05-24

15

Climate change effects on vegetation characteristics and groundwater recharge  

NASA Astrophysics Data System (ADS)

Climate change is among the most pressing issues of our time. Increase in temperature, a decrease in summer precipitation and increase in reference evapotranspiration might affect the water balance, freshwater availability and the spatial distribution and type of vegetation. Precipitation and evapotranspiration (ET) largely determine groundwater recharge. Therefore, climate change likely affects both the spatial and temporal freshwater availability for nature conservation, agriculture and drinking water supply. Moreover, in the coastal (dune) areas, the groundwater recharge is crucial to the maintenance of the freshwater bell and the dynamics of the fresh - salt interface. Current knowledge, however, is insufficient to estimate reliably the effects of climate change on future freshwater availability. Future groundwater recharge, the driving force of the groundwater system, can only be assessed if we understand how vegetation responds to changing climatic conditions, and how vegetation feedbacks on groundwater recharge through altered actual ET. Although the reference ET (i.e. the ET of a reference vegetation, defined as a short grassland completely covering the soil and optimally provided by water) is predicted to increase, the future actual ET (i.e. the ET of the actual ‘real' vegetation under the ‘real' moisture conditions) is highly unknown. It is the dynamics in the actual ET, however, through which the vegetation feeds back on the groundwater recharge. In an earlier study we showed that increased atmospheric CO2 raises the water use efficiency of plants, thus reducing ET. Here we demonstrate another important vegetation feedback in dune systems: the fraction of bare soil and non-rooting species (lichens and mosses) in the dune vegetation will increase when, according to the expectations, summers become drier. From our calculations it appeared that on south slopes of dunes, which receive more solar radiation and are warmer than north facing surfaces, the fraction of vascular plants may drop from 70 to 20 percent in the future (2050) climate due to increased moisture deficits. ET of bare soil and non-rooting species is much lower than that of vascular plants and thus the vegetation composition feeds back on the soil moisture conditions. Knowledge on such feedback mechanisms is indispensable in the analysis of climate change effects on the future groundwater recharge. Important questions are how, in the course of time, climate change will affect both groundwater table depth and dynamics, and how water management could adapt to these changes. We pursue a dynamic modeling approach that takes account of the interacting processes in the soil-plant-atmosphere system, including feedback mechanisms of the vegetation. This allows us to analyze climate change effects on groundwater recharge and thus future freshwater availability.

(Flip) Witte, J. P. M.; (Ruud) Bartholomeus, R. P.; (Gijsbert) Cirkel, D. G.

2010-05-01

16

Dune Exploration: Mars Allegories  

NASA Astrophysics Data System (ADS)

We know of one factual habitable planet, although other factual planets can be imagined as habitable. Sometimes the allegory is obvious. E.g., H. G. Wells imagined Martians exterminating humans as an allegory to Englishmen exterminating the Tasmanian aborigines, whilst Percival Lowell saw the global network of Martian canals as a world civilization that had progressed beyond war. But most habitable planets are overtly fictional. The planet properly known as Arrakis and colloquially known as Dune (Herbert 1965) provides an exceptionally well-developed example of a fictional habitable planet. In its particulars Dune resembles a warmer Mars with a breathable oxygen atmosphere. Like Mars, Dune is now a parched desert planet but there are signs that water flowed in the prehistoric past. Dune has small water ice caps at the poles and more extensive deep polar aquifers. The tropics are exceedingly dry but the polar regions are cool and moist enough to have morning dew. Dune is sparsely inhabited by a mix of indigenous and terran flora and fauna. The fictional Dune asks us to consider how much water is enough, why does oxygen accumulate in an atmosphere, and what actually sets the inner edge to the habitable zone. The inner edge of the habitable zone is conventionally set by the onset of the runaway greenhouse effect. The runaway greenhouse occurs when there is enough water vapor in the atmosphere to lift the planet's thermal photosphere off the ground. For a wet planet the mapping between saturation, temperature and optical depth is unique; together these set an upper limit on the rate the amount of thermal radiation that the planet can emit and still maintain a humid atmosphere. A dry atmosphere has a lower opacity for a given temperature, other things equal. With its vast dry equatorial deserts, a habitable Dune can radiate at a significantly higher effective temperature than a wet planet, and so it can provide an abode for life significantly closer to its sun. We use GCM modeling to show that liquid water can exist at places on the surface of a Dune-like planet at insolation levels as much as 170% of the present solar flux of the Earth.

Zahnle, K.; Sleep, N. H.; Abe, Y.; Abe-Ouchi, A.

2005-12-01

17

Rechargeable zinc halogen battery  

SciTech Connect

A rechargeable zinc halogen battery has an aqueous electrolyte containing ions of zinc and halogen and an amount of polysaccharide and/or sorbitol sufficient to prevent zinc dendrite formation during recharging. The electrolyte may also contain trace amounts of metals such as tungsten, molybdenum, and lead. 7 tables.

Spaziante, P.M.; Nidola, A.

1980-01-01

18

Portable photovoltaic battery recharger  

SciTech Connect

A portable photovoltaic battery recharger is described for simultaneously recharging a plurality of rechargeable batteries having different sizes and respective optimum charging current levels, comprising: a plurality of photovoltaic solar cell arrays corresponding to the number of different battery sizes, each of the cell arrays having a plurality of individual solar cells, each cell of a respective array having a selectively chosen surface area for generating the respective optimum charging current levels when insolated; battery receptacle means for holding the plurality of rechargeable batteries in a recharging position; and circuit means for connecting the plurality of photovoltaic solar cell arrays to the battery receptacle means to charge each of the different size batteries with the respective optimum charging current level.

Ricaud, A.M.; Artigliere, F.

1989-02-28

19

Beach and Dune.  

National Technical Information Service (NTIS)

The flora, vegetation, and microenvironment of beach and dune are sufficiently different to warrant their separate treatment in this chapter. Beach is defined here as the expanse of sandy substrate between mean tide and the foredune or, in the absence of ...

M. G. Barbour A. F. Johnson

1977-01-01

20

Dune formation under bimodal winds  

PubMed Central

The study of dune morphology represents a valuable tool in the investigation of planetary wind systems—the primary factor controlling the dune shape is the wind directionality. However, our understanding of dune formation is still limited to the simplest situation of unidirectional winds: There is no model that solves the equations of sand transport under the most common situation of seasonally varying wind directions. Here we present the calculation of sand transport under bimodal winds using a dune model that is extended to account for more than one wind direction. Our calculations show that dunes align longitudinally to the resultant wind trend if the angle ?w between the wind directions is larger than 90°. Under high sand availability, linear seif dunes are obtained, the intriguing meandering shape of which is found to be controlled by the dune height and by the time the wind lasts at each one of the two wind directions. Unusual dune shapes including the “wedge dunes” observed on Mars appear within a wide spectrum of bimodal dune morphologies under low sand availability.

Parteli, Eric J. R.; Duran, Orencio; Tsoar, Haim; Schwammle, Veit; Herrmann, Hans J.

2009-01-01

21

DuneXpress  

Microsoft Academic Search

The DuneXpress observatory will characterize interstellar and interplanetary dust in-situ, in order to provide crucial information\\u000a not achievable with remote sensing astronomical methods. Galactic interstellar dust constitutes the solid phase of matter\\u000a from which stars and planetary systems form. Interplanetary dust, from comets and asteroids, represents remnant material from\\u000a bodies at different stages of early solar system evolution. Thus, studies

Eberhard Grün; Ralf Srama; Nicolas Altobelli; Kathrin Altwegg; James Carpenter; Luigi Colangeli; Karl-Heinz Glassmeier; Stefan Helfert; Hartmut Henkel; Mihaly Horanyi; Annette Jäckel; Sascha Kempf; Markus Landgraf; Neil McBride; Georg Moragas-Klostermeyer; Pasquale Palumbo; Han Scholten; Andre Srowig; Zoltan Sternovsky; Xavier Vo

2009-01-01

22

City-swallowing Sand Dunes  

NSDL National Science Digital Library

At this Science at NASA site, you'll learn about the physics of sand movement and the research done to understand mechanisms of dune migration. The physics and the landforms are interesting because granular materials like sand show properties of both solids and fluids, including saltation, sheet flow, and avalanches. This site provides a summary of the physics involved along with photographs of sand dunes on Mars, close-ups of sand particles, and a sand dune advancing on a town.

Bell, Trudy E.

2007-06-19

23

DuneXpress  

NASA Astrophysics Data System (ADS)

The DuneXpress observatory will characterize interstellar and interplanetary dust in-situ, in order to provide crucial information not achievable with remote sensing astronomical methods. Galactic interstellar dust constitutes the solid phase of matter from which stars and planetary systems form. Interplanetary dust, from comets and asteroids, represents remnant material from bodies at different stages of early solar system evolution. Thus, studies of interstellar and interplanetary dust with DuneXpress in Earth orbit will provide a comparison between the composition of the interstellar medium and primitive planetary objects. Hence DuneXpress will provide insights into the physical conditions during planetary system formation. This comparison of interstellar and interplanetary dust addresses directly themes of highest priority in astrophysics and solar system science, which are described in ESA’s Cosmic Vision. The discoveries of interstellar dust in the outer and inner solar system during the last decade suggest an innovative approach to the characterization of cosmic dust. DuneXpress establishes the next logical step beyond NASA’s Stardust mission, with four major advancements in cosmic dust research: (1) analysis of the elemental and isotopic composition of individual interstellar grains passing through the solar system, (2) determination of the size distribution of interstellar dust at 1 AU from 10 - 14 to 10 - 9 g, (3) characterization of the interstellar dust flow through the planetary system, (4) establish the interrelation of interplanetary dust with comets and asteroids. Additionally, in supporting the dust science objectives, DuneXpress will characterize dust charging in the solar wind and in the Earth’s magnetotail. The science payload consists of two dust telescopes of a total of 0.1 m2 sensitive area, three dust cameras totaling 0.4 m2 sensitive area, and a nano-dust detector. The dust telescopes measure high-resolution mass spectra of both positive and negative ions released upon impact of dust particles. The dust cameras employ different detection methods and are optimized for (1) large area impact detection and trajectory analysis of submicron sized and larger dust grains, (2) the determination of physical properties, such as flux, mass, speed, and electrical charge. A nano-dust detector searches for nanometer-sized dust particles in interplanetary space. A plasma monitor supports the dust charge measurements, thereby, providing additional information on the dust particles. About 1,000 grains are expected to be recorded by this payload every year, with 20% of these grains providing elemental composition. During the mission submicron to micron-sized interstellar grains are expected to be recorded in statistically significant numbers. DuneXpress will open a new window to dusty universe that will provide unprecedented information on cosmic dust and on the objects from which it is derived.

Grün, Eberhard; Srama, Ralf; Altobelli, Nicolas; Altwegg, Kathrin; Carpenter, James; Colangeli, Luigi; Glassmeier, Karl-Heinz; Helfert, Stefan; Henkel, Hartmut; Horanyi, Mihaly; Jäckel, Annette; Kempf, Sascha; Landgraf, Markus; McBride, Neil; Moragas-Klostermeyer, Georg; Palumbo, Pasquale; Scholten, Han; Srowig, Andre; Sternovsky, Zoltan; Vo, Xavier

2009-03-01

24

Sand Dunes: A Phenomenon Of Wind  

NSDL National Science Digital Library

This webpage from Wayne's Word provides information about the origin of sand dunes, forms of life present there, and the sounds produced by "booming" dunes. Numerous dunes in the United States are described and pictured.

2010-06-29

25

Universal connector for rechargeable and non-rechargeable batteries  

Microsoft Academic Search

In an electrical product having battery recharging means and a load adapted for energization from a battery, a battery connector is described which consists of: terminal means adapted to contact the output terminals of either a non-rechargeable battery having a first physical configuration or a rechargeable battery having a second physical configuration, the terminal means coupled to the load of

G. R. Mundschenk; R. C. Decker

1986-01-01

26

Dune fields in central Western Argentina  

NASA Astrophysics Data System (ADS)

Important accumulations of wind blown sands extend over some sections of plains and pediments. The three dune fields existing in the area are called: Medanos Grandes (great dunes) in the south end of Pie de Palo range between 660 to 750 masl; Las Chacras dune to the southwestern end of Valle Fertil range between 690 to 800 masl; and Mascasin dunes between 450 to 550 masl. These dune fields contain longitudinal, transverse, parabolic, and barchanoid sand dunes with interdune basins.

Suvires, Graciela M.

27

Biogenic crust dynamics on sand dunes  

NASA Astrophysics Data System (ADS)

Sand dunes are often covered by vegetation and biogenic crusts. Despite their significant role in dune stabilization, biogenic crusts have rarely been considered in model studies of dune dynamics. Using a simple model, we study the existence and stability ranges of different dune-cover states along gradients of rainfall and wind power. Two ranges of alternative stable states are identified: fixed crusted dunes and fixed vegetated dunes at low wind power; and fixed vegetated dunes and active dunes at high wind power. These results suggest a crossover between two different forms of desertification.

Kinast, Shai; Meron, Ehud; Yizhaq, Hezi; Ashkenazy, Yosef

2013-02-01

28

Stability of isolated Barchan dunes  

NASA Astrophysics Data System (ADS)

When sand grains are entrained by an air flow over a non-erodible ground, or with limited sediment supply from the bed, they form isolated dunes showing a remarkable crescentic shape with horns pointing downstream. These dunes, known as Barchan dunes, are commonly observed in deserts, with height of a few meters and velocity of a few meters per year (Bagnold 1941). These dunes also exist under water, at a much smaller, centimetric size (Franklin & Charru 2010). Their striking stability properties are not well understood yet. Two phenomena are likely to be involved in this stability: (i) relaxation effects of the sand flux which increases from the dune foot up to the crest, related to grain inertia or deposition, and (ii) a small transverse sand flux due to slope effects and the divergence of the streamlines of the fluid flow. We reproduced aqueous Barchan dunes in a channel, and studied their geometrical and dynamic properties (in particular their shape, velocity, minimum size, and rate of erosion). Using coloured glass beads (see the figure), we were then able to measure the particle flux over the whole dune surface. We will discuss the stability of these dunes in the light of our measurements.

Fourrière, Antoine; Charru, François

2010-11-01

29

Apparatus for charging rechargeable battery  

Microsoft Academic Search

A rechargeable battery is supplied with a charging voltage from a charging voltage source and exhibits a charging voltage characteristic having a peak shortly before the rechargeable battery reaches a fully charged state. A resistor voltage dividing circuit having a plurality of voltage output terminals is connected to both terminals of the rechargeable battery. A voltage memory device is provided

K. Oyamada; K. Tada

1982-01-01

30

Rechargeable galvanic cell  

Microsoft Academic Search

An improved rechargeable cell is described which has an anode structure which in its uncharged state comprises a coherent metallic porous body with its pores substantially filled with oxidized zinc and alkaline electrolyte. This anode structure is generated in situ, within the cell, by exposing a predetermined admixture of active zinc metal and an oxide of a metal less anodically

1978-01-01

31

Rechargeable Alkaline Zinc System.  

National Technical Information Service (NTIS)

Rechargeable alkaline zinc batteries have been investigated heretofore as power sources capable of high energy density applications. One of the major problems with their use is the short circuiting of the unit cells by growth of zinc dendrites from the an...

O. C. Wagner

1970-01-01

32

Effect of species on dune grass growth  

Microsoft Academic Search

Observations of experimental dunes made over a period of nine years indicate differences in utilizing three different dune species along the North Carolina coast and in the type of dunes produced by them. Ammophila is superior in ease of establishment and rate of sand accumulation but is shortlived. It produces a gently sloping dune. Uniola is difficult to propagate but

W. W. Woodhouse; E. D. Seneca; S. W. Broome

1977-01-01

33

Effect of species on dune grass growth  

Microsoft Academic Search

Observations of experimental dunes made over a period of nine years indicate differences in utilizing three different dune species along the North Carolina coast and in the type of dunes produced by them.Ammophila is superior in ease of establishment and rate of sand accumulation but is shortlived. It produces a gently sloping dune.Uniola is difficult to propagate but is an

W. W. Woodhouse; E. D. Seneca; S. W. Broome

1977-01-01

34

REMOTELY RECHARGEABLE EPD  

SciTech Connect

Radiation measurements inside the Contact Decon Maintenance Cell (CDMC) in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) are required to determine stay times for personnel. A system to remotely recharge the transmitter of an Electronic Personnel Dosimeter (EPD) and bail assembly to transport the EPD within the CDMC was developed by the Savannah River National Laboratory (SRNL) to address this need.

Vrettos, N; Athneal Marzolf, A; Scott Bowser, S

2007-11-13

35

Water Table Fluctuations Induced by Intermittent Recharge  

Microsoft Academic Search

The problem of water table fluctuations in response to repeated recharges is considered. The effect on the water table of intermittent constant recharge (recharge applied intermittently at a constant rate) and of intermittent instantaneous recharge (recharge applied instantaneoulsy at regular intervals) is analyzed in detail. The final results are shown to consist of a combination of periodic and transient components;

Marinus Maasland

1959-01-01

36

A Dimensionless Parameter Study of Groundwater Recharge.  

National Technical Information Service (NTIS)

The method of coefficients has been used to predict groundwater recharge for several years. A new approach was attempted using a 'dimensionless parameter' concept to relate recharge to other known parameters, i.e., pumpage, permeability, rainfall, recharg...

G. A. Coleman J. K. Cheng J. F. Harp J. G. Laguros

1972-01-01

37

Universal connector for rechargeable and non-rechargeable batteries  

SciTech Connect

In an electrical product having battery recharging means and a load adapted for energization from a battery, a battery connector is described which consists of: terminal means adapted to contact the output terminals of either a non-rechargeable battery having a first physical configuration or a rechargeable battery having a second physical configuration, the terminal means coupled to the load of the product such that the load may be energized from either the non-rechargeable battery or the rechargeable battery; circuit means coupling the terminal means and the battery recharging means, the circuit means including a switch having an open state preventing charging through the circuit means of a battery coupled to the terminal means and a closed state permitting charging through the circuit means of a battery coupled to the terminal means; and biased actuating means coupled to the switch for moving the switch between its closed and open sites, the actuating means adapted to coact with the first physical configuration of a non-rechargeable battery to move the switch against a bias to its open state and adapted to coact with the second physical configuration of a rechargeable battery to allow the switch to move with the bias to its closed state; whereby the physical configurations of a battery connected to the battery connector determines whether or not the battery will be charged.

Mundschenk, G.R.; Decker, R.C.

1986-07-22

38

Novel rechargeable sodium batteries  

Microsoft Academic Search

The program was concerned with the development of a high energy density rechargeable sodium battery operating in the moderate temperature range of 175 to 200 C. The suitability of NaFeOâ and FeOCl as cathode materials in Na cells having the configuration--Molten Na\\/beta-AlâOâ\\/Molten NaAlC{sub l4}, NaFeOâ or FeOC{sub l}--has been studied. Cells containing either NaFeOâ or FeOCl were found to cycle

1988-01-01

39

Predicting vegetation-stabilized dune morphology  

NASA Astrophysics Data System (ADS)

The morphology of vegetation-stabilized dune fields on the North American Great Plains mostly comprises parabolic dunes; stabilized barchan and transverse dunes are rare. One notable exception is the Nebraska Sand Hills (NSH), where massive grass-covered barchan and transverse dunes bear proof of former desert-like conditions. We present a hypothesis from a numerical dune field model to explain the vegetation-stabilized morphology of dunes. The model incorporates a growth curve that preferentially grows vegetation in regions of sediment deposition with a sharp drop in growth at the peak depositional tolerance of vegetation, qualitatively matching biological response to erosion and deposition. Simulations on a range of pre-stabilization dune morphologies, from large closely-spaced transverse dunes to small dispersed barchans, indicate that the stabilized morphology is largely determined by the ratio of slipface deposition rate to peak depositional tolerance of vegetation. Conceptually, slipface deposition rate is related to dune height and celerity. By keeping depositional tolerance constant (representing a constant vegetation type and climate) the model shows that large slow-moving dunes have low slipface deposition rates and essentially 'freeze' in place once vegetation is introduced, retaining their pre-vegetation morphology. Small fast-moving dunes have higher slipface deposition rates and evolve into parabolic dunes. We hypothesize that, when barchan and transverse dunes are subjected to a stabilizing climate shift that increases vegetation growth rate, they retain their pre-stabilization morphology if deposition rates are below the depositional tolerance of stabilizing vegetation, otherwise they become parabolic dunes. This could explain why NSH dunes are stabilized in barchan and transverse morphologies while elsewhere on the Great Plains dune fields are dominated by smaller parabolic dunes.

Barchyn, T.; Hugenholtz, C.

2012-04-01

40

Heat transport in the vicinity of an artificial recharge site  

NASA Astrophysics Data System (ADS)

Since July 2002, the Intermunicipal Water Company of the Veurne region (IWVA) artificially recharges fresh water in the dunes of the western Belgian coastal plain by means of two recharge ponds. This recharge water is produced from secondary treated waste water effluent by the combination of ultra filtration and reverse osmosis. Extraction wells (112) are located north and south of the ponds. The artificial recharge project loops the water cycle: extracted water goes to the users and their waste water is purified and re-used. Therefore, it is an example of sustainable water management in coastal aquifers. Groundwater flow of this recharge site has been examined in the past by the use of a tracer test, hydrochemistry (environmental isotopes, conservative tracers) and groundwater flow modelling. Temperature, however, forms a relatively easy measurement which can add to or confirm the knowledge of the groundwater flow. Temperature time series (temperature as function of time) were measured at different levels in a number of wells located between the recharge ponds and the extraction wells, and in one well south of the recharge and extraction area. Secondly, temperature logs (temperature as function of depth) were measured in these wells at different times over the course of 2 years. Finally, the temperature of the recharged and extracted water is constantly monitored by the water company. The temperature of the recharge water shows a yearly fluctuation, ranging from 25 °C during summer to slightly above 0 °C during the winter. The temperature of the extracted water (combination of water extracted in all the wells) ranges between 17 °C during summer and 10 °C during winter. Minima and maxima in the extracted water are observed between 76 and 110 days (mean of 90 days and standard deviation of 13.5 days) later in the extracted water with respect to the recharged water. Measurements show that the difference in time when maxima and minima are observed in an observation well with reference to the ponds increases with depth (for instance from 28 days 4.1 m below surface to 154 days 10 m below surface for an observation well at 10 m from the ponds). This confirms previous flow modelling which showed that groundwater flows relatively rapidly laterally from the recharge ponds towards the extraction wells. Additionally, part of the recharge water flows in a deeper flow cycle towards the extraction wells. Residence times in this deeper flow cycle are evidently larger than in the direct lateral flow cycle from the ponds towards the wells. This explains the increase with depth. The 154 days (with respect to a mean time of 90 days) points to the fact that the extracted water contains a large spectrum of residence times with mean of 90 days for the heat transport, as was also derived by the flow modelling previously

Vandenbohede, Alexander; van Houtte, Emmanuel; Lebbe, Luc

2010-05-01

41

High Power Rechargeable Thermal Battery.  

National Technical Information Service (NTIS)

Report developed under STTR contract; a proof of concept for a portable, rechargeable thermal battery (RTB). Including a superinsulated case, a lightweight (10 lb) RTB can provide 250W for 2-6h at 140 Wh/kg with days of activation between recharging. It c...

T. D. Kaun

1997-01-01

42

Using Overlapping MOC Images to Search for Dune Movement and to Measure Dune Heights  

NASA Astrophysics Data System (ADS)

Overlapping MOC images have been used to search for dune movement and to measure dune heights. No dune movement was found, but dune heights in Proctor and Rabe were measured at 30-100 m. A possible cinder cone in Proctor has also been identified.

Williams, K. K.; Greeley, R.; Zimbelman, J. R.

2003-03-01

43

Kappakoola dunes — aeolian landforms induced by man  

Microsoft Academic Search

The Kappakoola dunes are located on central Eyre Peninsula, in South Australia. These masses of sand stand out from the northwest?southeast trending longitudinal dunes of the regional pattern because they are devoid of vegetation and in detail change in morphology from day to day according to the wind direction. The dunes are demonstrably of recent origin and are developed as

Dianne M. Smith; C. R. Twidale; Jennifer A. Bourne

1975-01-01

44

Water recharge in Larderello Geothermal field  

SciTech Connect

In this paper, the variations in fluid composition observed in area of Larderello field that are strongly affected by induced recharge are ascribed to a simple mechanism, and a comprehensive conceptual model is presented for these areas. According to out interpretation, the steam produced in areas affected by induced recharge is a mixture of two components (steam from recharge water and original deep steam). The natural recharge increased and recharge became an important phenomenon as a consequence of the pressure drawdown caused by exploitation. Three separate estimates of the water recharge give similar results and confirm that a significant fraction of the produced steam derives from recharge water.

Celati, R.; Calore, C.; Grassi, S.; D'Amore, F. (CNR International Int. for Geothermal Research, Piazza Solferino 2, 56126 Pisa (IT)); Cappetti, G. (ENEL Vice-Direction of Geothermal Activity, Via Andrea Pisano 120, 56122 Pisa (IT))

1991-01-01

45

Rechargeable natrium batteries. (Genopladelige natriumbatterier).  

National Technical Information Service (NTIS)

Investigations on rechargeable molten salt batteries have been carried out. Molten chloride aluminates have been used as electrolytes, and aluminium as anodes, the cathodes have often been transient metal sulphides. Furthermore, investigations on natrium ...

H. Hjuler B. C. Knutz B. Vestergaard N. J. Bjerrum

1992-01-01

46

Advanced Rechargeable Batteries, Phase 2.  

National Technical Information Service (NTIS)

In the framework of the program Advanced rechargeable batteries, intended to evaluate the suitability, the applicability and possible problems of advanced batteries on naval ships (both surface and submarine) studies and tests have been performed on two p...

I. D. Schmal I. W. ter Veen I. C. Kluiters

1999-01-01

47

Apparatus for charging rechargeable battery  

SciTech Connect

A rechargeable battery is supplied with a charging voltage from a charging voltage source and exhibits a charging voltage characteristic having a peak shortly before the rechargeable battery reaches a fully charged state. A resistor voltage dividing circuit having a plurality of voltage output terminals is connected to both terminals of the rechargeable battery. A voltage memory device is provided for storing a predetermined voltage based on a voltage supplied from the voltage dividing circuit corresponding to the peak point of the charging voltage characteristic and comparison is made of the other output voltage obtained from the voltage dividing circuit after the peak point is passed and the stored voltage in the voltage memory device and a supply of a charging power from the charging voltage source to the rechargeable battery is interrupted when the difference between these voltages becomes zero.

Oyamada, K.; Tada, K.

1982-10-12

48

Electrically Rechargeable Redox Flow Cell.  

National Technical Information Service (NTIS)

A bulk energy storage system is described. The system includes an electrically rechargeable reduction-oxidation cell divided by a membrane into two compartments, each containing an electrode. An anode fluid is directed through the first compartment at the...

L. H. Thaller

1975-01-01

49

Novel rechargeable sodium batteries  

SciTech Connect

The program was concerned with the development of a high energy density rechargeable sodium battery operating in the moderate temperature range of 175 to 200 C. The suitability of NaFeO{sub 2} and FeOCl as cathode materials in Na cells having the configuration--Molten Na/beta-Al{sub 2}O{sub 3}/Molten NaAlC{sub l4}, NaFeO{sub 2} or FeOC{sub l}--has been studied. Cells containing either NaFeO{sub 2} or FeOCl were found to cycle about 3 Na per Fe reversibly, in a two step discharge. The voltage profiles of cells containing either of these materials are strikingly similar. Chemical reactions between the NaAlC{sub l4} electrolyte and NaFeO{sub 2} or FeOCl have been proposed which suggest the formation of the identical intermediate in cells of either type. The quasi-theoretical specific energy is 1545 Wh/kg for the Na/NaFeO{sub 2} couple, and 1475 Wh/kg for the Na/FeOCl cell. When the possible involvement of one mole of NaAlCl4 in the discharge reaction is considered, these values become 628 Wh/kg for the former, and 603 Wh/kg for the latter.

Abraham, K.M.

1988-07-28

50

Formation Mechanisms for Dunes Observed on Titan  

NASA Astrophysics Data System (ADS)

The Cassini spacecraft has discovered massive dune fields on Saturn’s largest moon, Titan. The dunes were observed with the Cassini Synthetic Aperture Radar Imaging (SARS) instrument. The radar instrument operates at a frequency of 13.78 GHz, corresponding to a wavelength 2.2 cm. The resolution for the images examined are ~ 1 pixel = 175 m (varies from image to image). These dunes, or at least what’s visible to radar, through the thick nitrogen Titan atmosphere, seem to be almost exclusively longitudinal dunes (with crests forming parallel to prevailing wind directions). Many unanswered questions remain about these dunes. One goal of this project is to attempt to calculate the heights of these dunes, which has not yet been systematically attempted. We will use radar parallax analyses to calculate the height of the dunes. The Cassini radar determines position based on how long the radar wave took to return to the spacecraft, making an assumption that the surface is a perfect sphere. With changes in height, the time return for radar will change, distorting the image. Looking at these distortions (specifically, the shortening or elongation of the side of a dune) and knowing the inclination angle, we can determine height or depth. We will also use this same method with radar images of the Namib dunes, in southwest Africa, as an Earth analog, to test and determine how accurate our method is. This approach should give useful information on the morphology of the dunes on Titan. Knowing more about the morphology of the dunes can teach us more about the dune’s composition and formation mechanisms.

Vinson, Alec; Hays, C. C.; Lopes-Gautier, R. M.; Mitchell, K. L.; Diniega, S.; Farr, T. G.

2013-01-01

51

Daily cycles in coastal dunes  

USGS Publications Warehouse

Daily cycles of summer sea breezes produce distinctive cyclic foreset deposits in dune sands of the Texas and Oregon coasts. In both areas the winds are strong enough to transport sand only during part of the day, reach a peak during the afternoon, and vary little in direction during the period of sand transport. Cyclicity in the foreset deposits is made evident by variations in the type of sedimentary structure, the texture, and the heavy-mineral content of the sand. Some of the cyclic deposits are made up entirely of one basic type of structure, in which the character of the structure varies cyclically; for example, the angle of climb in a climbing-wind-ripple structure may vary cyclically. Other cyclic deposits are characterized by alternations of two or more structural types. Variations in the concentration of fine-grained heavy minerals, which account for the most striking cyclicity, arise mainly because of segregation on wind-rippled depositional surfaces: where the ripples climb at low angles, the coarsegrained light minerals, which accumulate preferentially on ripple crests, tend to be excluded from the local deposit. Daily cyclic deposits are thickest and best developed on small dunes and are least recognizable near the bases of large dunes. ?? 1988.

Hunter, R. E.; Richmond, B. M.

1988-01-01

52

Modeling Megacusps and Dune Erosion  

NASA Astrophysics Data System (ADS)

Megacusps are large, concave, erosional features of beaches, of O(200m) alongshore wavelength, which sometimes occur when rip channel bathymetry is present. It is commonly hypothesized that erosion of the dune and back beach will be greater at the alongshore locations of the megacusp embayments, principally because the beach width is narrower there and larger waves can more easily reach the dune toe (e.g., Short, J. Geol., 1979, Thornton, et al., Mar. Geol., 2007). At present, available field data in southern Monterey Bay provide some support for this hypothesis, but not enough to fully confirm or refute it. This analysis utilizes XBeach, a 2DH nearshore sediment transport model, to test the above hypothesis under a range of wave conditions over several idealized rip-megacusp bathymetries backed by dunes. Model results suggest that while specific wave conditions may result in erosional hot spots at megacusp embayments, other factors such as tides, wave direction, and surf zone bathymetry can often play an equal or stronger role.

Orzech, M.; Reniers, A. J.; Thornton, E. B.

2009-12-01

53

Early evaluation of a rechargeable pacemaker system.  

PubMed

A rechargeable demand pulse generator for permanent transvenous cardiac pacing was evaluated in 66 patients. During a cumulative follow-up period of 895 patient months there was no instance of failure of either the pulse generator or of the recharging circuit. Acceptance of the recharging concept was high, there being only one patient in whom it was necessary to replace the rechargeable generator because of inability to master the recharging technique. The early findings indicate that with proper patient selection the rechargeable pulse generator promises to be an important contribution to pacemaker therapy. PMID:978092

Stertzer, S H; DePasquale, N P; Bruno, M S; Cohn, L J

1976-01-01

54

Functional materials for rechargeable batteries.  

PubMed

There is an ever-growing demand for rechargeable batteries with reversible and efficient electrochemical energy storage and conversion. Rechargeable batteries cover applications in many fields, which include portable electronic consumer devices, electric vehicles, and large-scale electricity storage in smart or intelligent grids. The performance of rechargeable batteries depends essentially on the thermodynamics and kinetics of the electrochemical reactions involved in the components (i.e., the anode, cathode, electrolyte, and separator) of the cells. During the past decade, extensive efforts have been dedicated to developing advanced batteries with large capacity, high energy and power density, high safety, long cycle life, fast response, and low cost. Here, recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed. The focus is on research activities toward the ionic, atomic, or molecular diffusion and transport; electron transfer; surface/interface structure optimization; the regulation of the electrochemical reactions; and the key materials and devices for rechargeable batteries. PMID:21394791

Cheng, Fangyi; Liang, Jing; Tao, Zhanliang; Chen, Jun

2011-03-11

55

High Plains States Groundwater Demonstration Program. Rillito Recharge Project Artificial Groundwater Recharge Project Artificial Groundwater Recharge Demonstration Project Summary.  

National Technical Information Service (NTIS)

This report summarizes the development, conduct, and findings of the Rillito Recharge Project. Detailed information can be found in the Final Report: Rillito Recharge Project. The project is one of 13 demonstration projects by the Bureau of Reclamation (R...

1996-01-01

56

Dunes On Titan: Comparison Of The Fensal And Belet Dune Regions Using Multiple Datasets  

Microsoft Academic Search

Titan's equatorial belt hosts large expanses of longitudinal dunes. As the Cassini mission continues, more of them are unveiled by the microwave RADAR, both in the active and passive modes and with an increasing number of viewing geometries. These observations have revealed some variations among dune regions. In particular, we find that the Belet and Fensal dune fields differ in

Alice Le Gall; M. A. Janssen; L. C. Wye; A. G. Hayes; R. D. Lorenz; J. Radebaugh; B. Stiles

2010-01-01

57

A new method for mapping groundwater recharge areas and for zoning recharge for an inverse model  

Microsoft Academic Search

This thesis presents a new methodology for delineating groundwater recharge and discharge areas. Estimates of recharge rates and locations of recharge areas are important components in strategies for managing groundwater resources. The main contribution of this thesis is a method for zoning recharge for parameter-estimation (inverse) models. The importance of the zoning method presented here is that it is objective,

Stoertz

1989-01-01

58

Recharge characteristics of a phreatic aquifer as determined by storage accumulation  

NASA Astrophysics Data System (ADS)

The cumulative storage accumulation curve (CSAC) is a tool for saturated-volume fluctuation (SVF) analysis of transient recharge to shallow phreatic aquifers discharging only to springs. The method assumes that little underflow or phreatic evapotranspiration occurs. The CSAC is a modified water-table hydrograph that distinguishes storage increase caused by recharge from loss due to springflow-induced recession. Required for the analysis are water-table fluctuations at a single representative location within the catchment of a single spring and either direct measurements or robust interpolations of springflows at different aquifer stages. The method employs empirical manipulation of head observations, varying spring catchment area to minimize CSAC water-level changes in late portions of long recessions. Results include volumetric estimates of recharge integrated over individual events and instantaneous rates of recharge to the water table, at the temporal resolution of the water-level sampling interval. The analysis may also yield physically realistic information on spring catchment and recharge focusing. In a test case in West Virginia, USA, recharge estimates by this technique were consistent with integrated springflow time series but greater than estimates based on potential evapotranspiration. Results give insight into dynamic recharge behavior over time as well as an indication of recharge catchment size. Résumé. La courbe cumulative de stockage est un outil d'analyse de la fluctuation du volume de la zone saturée en recharge transitoire de nappes peu profondes se déchargeant uniquement par des sources. La méthode suppose que les effets de la drainance ou de l'évapotranspiration sont faibles. La courbe cumulative de stockage est un hydrogramme de nappe modifié qui fait la distinction entre l'accroissement du stockage dû à la recharge et les pertes dues à la récession liée à l'écoulement aux sources. Sont nécessaires pour cette analyse les fluctuations de la nappe en un point unique représentatif du bassin d'alimentation d'une source unique et soit des mesures directes soit des interpolations robustes des écoulements à la source pour les différents états de l'aquifère. La méthode recourt à une manipulation empirique des observations de la piézométrie, faisant varier l'extension du bassin d'alimentation de la source, afin de minimiser les variations du niveau de la nappe liées à la courbe cumulative de stockage dans les parties lointaines des longues récessions. Les résultats prennent en compte les estimations de volume de la recharge intégré sur des événements individuels et sur des taux instantanés de recharge de la nappe, pour une résolution temporelle de l'intervalle d'observation de la nappe. L'analyse peut aussi fournir une information physiquement réaliste sur le bassin d'alimentation de la source et sur la concentration de la recharge. Dans un test effectué en Virginie occidentale (États-Unis), les estimations de la recharge par cette technique concordaient avec la chronique des débits de la source, mais étaient supérieures à celles basées sur l'évapotranspiration potentielle. Les résultats donnent un aperçu sur le comportement de la recharge dynamique au cours du temps aussi bien qu'une indication sur l'étendue de l'aire de recharge. Resumen. La curva acumulativa de incremento de almacenamiento (acrónimo CSAC, en inglés) es una herramienta para analizar la fluctuación del volumen saturado debida a la recarga transitoria en acuíferos freáticos someros que descargan únicamente por medio de manantiales. El método presupone que la evapotranspiración desde el nivel freático es pequeña. El CSAC es un hidrógrafo modificado del nivel freático, que permite distinguir el aumento de almacenamiento causado por la recarga de la descarga a través de los manantiales. El análisis requiere conocer las fluctuaciones del nivel freático en un punto representativo dentro de la cuenca de un manantial y, o bien medidas o bien interpolaciones robustas de los caudales en el

Ketchum, Neil; Donovan, Joseph; Avery, William

2000-09-01

59

Discharging and recharging of anomalous positive charges in MOSFETs  

Microsoft Academic Search

The discharging of positive charges is found to increase with bias. Following the same discharging, higher recharging bias leads to larger recharging of APC. However, under the same recharging bias with different previous discharging, the recharging does show a different response. In particular, there is larger recharging after the larger previous discharging, whatever the same recharging bias

Yongjun Wu; Mingzhen Xu; Changhua Tan; Jianlin Wei; Yi Liang; Yangyuan Wang

1998-01-01

60

Water recharge in Larderello Geothermal field  

Microsoft Academic Search

In this paper, the variations in fluid composition observed in area of Larderello field that are strongly affected by induced recharge are ascribed to a simple mechanism, and a comprehensive conceptual model is presented for these areas. According to out interpretation, the steam produced in areas affected by induced recharge is a mixture of two components (steam from recharge water

R. Celati; C. Calore; S. Grassi; F. DAmore; G. Cappetti

1991-01-01

61

Reusable Energy and Power Sources: Rechargeable Batteries  

ERIC Educational Resources Information Center

|Rechargeable batteries are very popular within consumer electronics. If one uses a cell phone or portable electric tool, she/he understands the need to have a reliable product and the need to remember to use the recharging systems that follow a cycle of charge/discharge. Rechargeable batteries are being called "green" energy sources. They are a…

Hsiung, Steve C.; Ritz, John M.

2007-01-01

62

Apparatus for successively charging rechargeable batteries  

Microsoft Academic Search

A charging apparatus charges a plurality of rechargeable batteries individually and in succession. Each of the plurality of rechargeable batteries is coupled to one corresponding charging branch. The charging apparatus comprises a charging completion detecting circuit for detecting a charging completion of a rechargeable battery now in a charging operation, a high voltage detecting circuit for detecting an abnormal voltage

K. Matsuura; K. Oyamada

1983-01-01

63

Manganese oxide cathodes for rechargeable batteries  

Microsoft Academic Search

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol

Dongmin Im

2002-01-01

64

Cementation in High-Latitude Dunes.  

National Technical Information Service (NTIS)

Cementing of dune sands by carbonates has not been considered to proceed rapidly in high-latitude regions. This study indicates that dunes along the Scotland coast, however, are actively being cemented by carbonates and that this process is quite widespre...

H. H. Roberts W. Ritchie A. Mather

1973-01-01

65

Rechargeable lithium polymer electrolyte batteries  

Microsoft Academic Search

Rechargeable lithium polymer electrolyte batteries have been under development for over ten years. The organic electrolyte has a low-vapor pressure and, in principle, during times of abuse, will be safe with respect to volatilization, ignition, and explosion. The electrolyte can be fabricated in the form of a thin solid film so no other separator element is required. Thus, the very

Boone B. Owens

1992-01-01

66

Winds drive dune movement on Mars  

NASA Astrophysics Data System (ADS)

Sand dunes, a common feature on the surface of Mars, can provide a record of recent and past changes. Some dunes near Mars's polar areas have recently been observed to change due to carbon dioxide ice sublimation, but it has not been confirmed whether dunes are still active all over Mars. Winds contribute to dune movement on Earth, but wind tunnel and atmospheric computer simulations have suggested that strong winds would be rare in the current Martian atmosphere. In a new study, Silvestro et al. observe recent dune movement in Mars's tropical regions, which are not affected by seasonal changes in carbon dioxide frost. Focusing on the Arabia Terra and Meridiani regions on Mars, the researchers analyzed images from the High Resolution Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter as well as other sources of data. They measured migration rates of two groups of ripples in the sand in a dune field in Meridiani Planum and found that dunes advanced about 0.4-1 meter in a Martian year.

Balcerak, Ernie

2012-01-01

67

Reestablishing Naturally Functioning Dunes on Developed Coasts.  

PubMed

/ The potential for reestablishing dune habitat is investigated in municipalities in New Jersey, USA, where natural coastal landforms and biota have been eliminated or reduced in extent. Dunes are classified using width, relationship to natural and cultural features, and changes through time, and they are assessed for their value as naturally functioning landforms in developed municipalities. The relationship between size and longevity that exists under natural conditions is altered by human activity. Small dunes on privately owned lots can survive as long as larger dunes in natural areas that are located farther inland, and foredunes repaired using sand fences and earth-moving equipment can survive where they could not under natural conditions.Common beach management practices reduce the ecological values of coastal dunes. Mechanical beach cleaning eliminates incipient dunes, habitat for nesting birds, seed sources for pioneer dune colonizers and food for fauna, and artificially small, stabilized foredunes reduce the variability in microenvironments necessary for biodiversity. Recent initiatives for reducing coastal hazards, protecting nesting birds, and encouraging nature-based tourism provide incentive for the development of a restoration program for beaches and dunes that is compatible with human use. Suggested changes in management practice include restricting or rerouting pedestrian traffic, altering beach-cleaning procedures, using symbolic fences to allow for aeolian transport while preventing trampling of dunes, and eliminating or severely restricting exotic species. Landforms will be more natural in function and appearance but will be more dynamic, smaller and in a different position from those in natural areas. Research needs are specified for ecological, geomorphological, and attitudinal studies to support and inform restoration planning. PMID:10552101

Nordstrom; Lampe; Vandemark

2000-01-01

68

Conceptual models of the evolution of transgressive dune field systems  

NASA Astrophysics Data System (ADS)

This paper examines the evolutionary paths of some transgressive dune fields that have formed on different coasts of the world, and presents some initial conceptual models of system dynamics for transgressive dune sheets and dune fields. Various evolutionary pathways are conceptualized based on a visual examination of dune fields from around the world. On coasts with high sediment supply, dune sheets and dune fields tend to accumulate as large scale barrier systems with little colonization of vegetation in arid-hyper to arid climate regimes, and as multiple, active discrete phases of dune field and deflation plain couplets in temperate to tropical environments. Active dune fields tend to be singular entities on coasts with low to moderate sediment supply. Landscape complexity and vegetation richness and diversity increases as dune fields evolve from simple active sheets and dunes to single and multiple deflation plains and basins, precipitation ridges, nebkha fields and a host of other dune types associated with vegetation (e.g. trailing ridges, slacks, remnant knobs, gegenwalle ridges and dune track ridges, 'tree islands' and 'bush pockets'). Three principal scenarios of transgressive dune sheet and dune field development are discussed, including dune sheets or dune fields evolving directly from the backshore, development following foredune and/or dune field erosion, and development from the breakdown or merging of parabolic dunes. Various stages of evolution are outlined for each scenario. Knowledge of evolutionary patterns and stages in coastal dune fields is very limited and caution is urged in attempts to reverse, change and/or modify dune fields to 'restore' some perceived loss of ecosystem or dune functioning.

A. Hesp, Patrick

2013-10-01

69

Mapping the Stratigraphy of Booming Sand Dunes  

NASA Astrophysics Data System (ADS)

Booming dunes emit a loud rumbling sound after a man-made or natural sand avalanche is generated on the slip face of a large desert dune. The sound consist of one dominant frequency (70 - 105 Hz) with several higher harmonics. A recent publication (Vriend et al., 2007) presented a model of an internal, natural waveguide that propagates the booming emission, amplifies the sound, and sets the booming frequency. The mapping of the subsurface layering, which is necessary for the existence of a waveguide, prompted additional work on the dune structure and stratigraphy. The current work highlights geophysical measurements at Eureka Dunes in Death Valley National Park, CA and Dumont Dunes in the Mojave Desert, CA. Seismic refraction studies indicate strong layering with large velocity jumps across the interfaces. Ground Penetrating Radar (GPR) profiles, at frequencies of 100 MHz and 200 MHz, map out the stratigraphic structure of the dunes. Variations in the near surface layering are able to predict the seasonal variability in booming frequency both quantitatively and qualitatively. The Kirchhoff migrated GPR profiles are superimposed on the local topography obtained with a laser rangefinder. The complex dune structure is resolved to a depth of over 30 meters for the 100 MHz antenna. The GPR profiles of the longitudinal Eureka dune display complex internal structures from old dune crests. Both slopes have slip faces at 30 degrees with parallel layering (< 2m) at the near surface. At the transverse Dumont dune the GPR profile exhibits strong parallel layering on the booming leeward slipface only. The shallower windward face features a remarkable tilted repetitive layering that cuts through the surface. At Dumont Dunes the layering on the leeward face explains the change in booming frequency between 70 - 95 Hertz in the period 2005 - 2008. The tilted layering structure of the shallow windward face prevents the formation of a waveguide and is never able to sustain the booming sound. The Dumont dune progresses slowly, estimated at ~ 1 m/year from correlating satellite images, by forming new slip faces on the leeward face over time. Large precipitation events may cause a new layer to form. Sand sampling provides a quantitative measure on the chemical composition and water content of the layering.

Vriend, N. M.; Hunt, M. L.; Clayton, R. W.

2008-12-01

70

Calculation of the separation streamlines of barchans and transverse dunes  

Microsoft Academic Search

We use FLUENT to calculate the wind profile over barchans and transverse dunes. The form of the streamlines of flow separation at the lee side of the dunes is determined for a symmetric barchan dune in three dimensions, and for the height profile of a measured transverse dune field in the Lençóis Maranhenses.

H. J. Herrmann; J. S. Andrade Jr.; V. Schatz; G. Sauermann; E. J. R. Parteli

2005-01-01

71

A large-scale laboratory evaluation of dune erosion models  

Microsoft Academic Search

Simple models for dune erosion are necessary for bridging the gap between event scale predictions and probabilistic forecasts of long term coastal change. Dune erosion may be parameterized in terms of the elevation of the total water level (composed of surge, tide, and wave runup) above the dune base and period of exposure of the dune to waves. In this

M. L. Palmsten; R. A. Holman

2010-01-01

72

Hydrogeochemical transport modeling of the infiltration of tertiary treated wastewater in a dune area, Belgium  

NASA Astrophysics Data System (ADS)

Managed artificial recharge (MAR) is a well-established practice for augmentation of depleted groundwater resources or for environmental benefit. At the St-André MAR site in the Belgian dune area, groundwater resources are optimised through re-use of highly treated wastewater by means of infiltration ponds. The very high quality of the infiltration water sets this system apart from other MAR systems. The low total dissolved solid (TDS) content in the infiltration water (less than 50 mg/L) compared to the dune aquifer (500 mg/L) triggers a number of reactions, increasing the TDS through soil-aquifer passage. Multi-component reactive transport modelling was applied to analyse the geochemical processes that occur. Carbonate dissolution is the main process increasing the TDS of the infiltration water. Oxic aquifer conditions prevail between the infiltration ponds and the extraction wells. This is driven by the high flow velocities, leaving no time to consume O2 between the ponds and extraction wells. Cation exchange is important when infiltration water is replaced by native dune water or when significant changes in infiltration-water quality occur. The seasonal variation of O2 and temperature in the infiltration water are the main drivers for seasonal changes in the concentration of all major ions.

Vandenbohede, Alexander; Wallis, Ilka; Van Houtte, Emmanuel; Van Ranst, Eric

2013-09-01

73

Early diagenesis of eolian dune and interdune sands at White Sands, New Mexico  

USGS Publications Warehouse

The degree of early diagenesis in eolian dune and interdune sands at White Sands, New Mexico, is largely a function of the relationship between sand location and the water table. Most active and vegetation-stabilized dune sands are in the vadose zone, whereas interdune sands are in the capillary fringe and phreatic zones. Crystallographically controlled dissolution of the framework gypsum grains results in elongate, prismatic etch pits on sand grains from the capillary fringe and phreatic zones, whereas dissolution of sand grains in the vadose zone is slight, causing minute irregularities on grain surfaces. Vadose water percolating through the sand is manifest as meniscus layers. Consequently, dune sands in the vadose zone are cemented mainly by meniscus-shaped gypsum at grain contacts. Pendant cements formed on the lower margins of some sand grains. Cementation in the capillary fringe and the phreatic zone is more extensive than the vadose regardless of strata type. Typically, well-developed gypsum overgrowths form along the entire edge of a grain, or may encompass the entire grain. Complex diagenetic histories are suggested by multiple overgrowths and several episodes of dissolution on single grains, attesting to changing saturation levels with respect to gypsum in the shallow ground water. These changes in saturation are possibly due to periods of dilution by meteoric recharge, alternating with periods of concentration of ions and the formation of cement due to evaporation through the capillary fringe. ?? 1988.

Schenk, C. J.; Fryberger, S. G.

1988-01-01

74

Groundwater recharge and agricultural contamination  

USGS Publications Warehouse

Agriculture has had direct and indirect effects on the rates and compositions of groundwater recharge and aquifer biogeochemistry. Direct effects include dissolution and transport of excess quantities of fertilizers and associated materials and hydrologic alterations related to irrigation and drainage. Some indirect effects include changes in water-rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agrilcultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3-, N2, Cl, SO42-, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well a wide variety of pesticides and other organic compounds. For reactive contaminants like NO3-, a combination of chemical, isotopic, and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. Groundwater records derived from multi-component hydrostratigraphic data can be used to quantify recharge rates and residence times of water and dissolved contaminants, document past variations in recharging contaminant loads, and identify natural contaminant-remediation processes. These data indicate that many of the world's surficial aquifers contain transient records of changing agricultural contamination from the last half of the 20th century. The transient agricultural groundwater signal has important implications for long-term trends and spatial heterogeneity in discharge.

Bohlke, J. -K.

2002-01-01

75

Groundwater recharge and agricultural contamination  

NASA Astrophysics Data System (ADS)

Agriculture has had direct and indirect effects on the rates and compositions of groundwater recharge and aquifer biogeochemistry. Direct effects include dissolution and transport of excess quantities of fertilizers and associated materials and hydrologic alterations related to irrigation and drainage. Some indirect effects include changes in water-rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3 -, N2, Cl, SO4 2-, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well as a wide variety of pesticides and other organic compounds. For reactive contaminants like NO3 -, a combination of chemical, isotopic, and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. Groundwater records derived from multi-component hydrostratigraphic data can be used to quantify recharge rates and residence times of water and dissolved contaminants, document past variations in recharging contaminant loads, and identify natural contaminant-remediation processes. These data indicate that many of the world's surficial aquifers contain transient records of changing agricultural contamination from the last half of the 20th century. The transient agricultural groundwater signal has important implications for long-term trends and spatial heterogeneity in discharge.

Böhlke, John-Karl

2002-02-01

76

Multilevel Multisensor-Based Intelligent Recharging System for Mobile Robot  

Microsoft Academic Search

Based on the sensor-based detection method, this paper presents an intelligent recharging system for a mobile robot. First, we design a flexible and reasonable intelligent recharging system for the mobile robot. It consists of a recharging station, a recharging device, and an intelligent power-detection module. The recharging station is designed to have 2 DOFs, such that it can move along

Ren C. Luo; Kuo L. Su

2008-01-01

77

Evaluation of a rechargeable pacemaker system.  

PubMed

A rechargeable-demand nickel-cadmium pulse generator for permanent transvenous cardiac pacing was evaluated in 66 patients. During a cumulative follow-up period of 2,333 patient months (194.4 patient years), failure of the pacing circuit occurred in 3 patients at 21, 25, and 27 months, respectively. Nine patients had difficulty accepting the recharging concept and, in 3 of these patients, it became necessary to replace the rechargeable generator with a conventional energy source. The overall failure rate of approximately 3% per year (including the 3 patients in whom it was necessary to remove the generator because of failure to recharge properly), coupled with the inconvenience of recharging, limits the usefulness of the rechargeable system compared to the newer lithium-powered generator. PMID:83632

Stertzer, S H; DePasquale, N P; Cohn, L J; Bruno, M S

1978-04-01

78

Palaeoclimatic Interpretations From Desert Dunes and Sediments  

Microsoft Academic Search

During the late Quaternary, the world’s major deserts experienced dramatic changes in the nature and frequency of aeolian\\u000a processes (Fig. 26.1). Sand seas (ergs) cover 5% of the global land surface and reveal evidence of repeated phases of dune\\u000a formation (Thomas et al. 2005). This paper presents a review of dune-building episodes during late Quaternary time and their\\u000a palaeoclimatic significance.

Vatche P. Tchakerian

79

Choosing appropriate techniques for quantifying groundwater recharge  

Microsoft Academic Search

.   Various techniques are available to quantify recharge; however, choosing appropriate techniques is often difficult. Important\\u000a considerations in choosing a technique include space\\/time scales, range, and reliability of recharge estimates based on different\\u000a techniques; other factors may limit the application of particular techniques. The goal of the recharge study is important\\u000a because it may dictate the required space\\/time scales of

Bridget R. Scanlon; Richard W. Healy; Peter G. Cook

2002-01-01

80

Using groundwater levels to estimate recharge  

Microsoft Academic Search

.   Accurate estimation of groundwater recharge is extremely important for proper management of groundwater systems. Many different\\u000a approaches exist for estimating recharge. This paper presents a review of methods that are based on groundwater-level data.\\u000a The water-table fluctuation method may be the most widely used technique for estimating recharge; it requires knowledge of\\u000a specific yield and changes in water levels

Richard W. Healy; Peter G. Cook

2002-01-01

81

Identifying and quantifying urban recharge: a review  

Microsoft Academic Search

.   The sources of and pathways for groundwater recharge in urban areas are more numerous and complex than in rural environments.\\u000a Buildings, roads, and other surface infrastructure combine with man-made drainage networks to change the pathways for precipitation.\\u000a Some direct recharge is lost, but additional recharge can occur from storm drainage systems. Large amounts of water are imported\\u000a into most

David N. Lerner

2002-01-01

82

Variability in simulated recharge using different GCMs  

NASA Astrophysics Data System (ADS)

Variations in the prediction of recharge is addressed by comparing recharge simulated using climate data generated using a state-of-the-art downscaling method, TreeGen, with a range of global climate models (GCMs). The study site is the transnational Abbotsford-Sumas aquifer in coastal British Columbia, Canada and Washington State, USA, and is representative of a wet coastal climate. Sixty-four recharge zones were defined based on combinations of classed soil permeability, vadose zone permeability, and unsaturated zone depth (or depth to water table) mapped in the study area. One-dimensional recharge simulations were conducted for each recharge zone using the HELP hydrologic model, which simulates percolation through a vertical column. The HELP model is driven by mean daily temperature, daily precipitation, and daily solar radiation. For the historical recharge simulations, the climate data series was generated using the LARS-WG stochastic weather generator. Historical recharge was compared to recharge simulated using climate data series derived from the TreeGen downscaling model for three future time periods: 2020s (2010-2039), 2050s (2040-2069), and 2080s (2070-2099) for each of four GCMs (CGCM3.1, ECHAM5, PCM1, and CM2.1). Recharge results are compared on an annual basis for the entire aquifer area. Both increases and decreases relative to historical recharge are simulated depending on time period and model. By the 2080s, the range of model predictions spans -10.5% to +23.2% relative to historical recharge. This variability in recharge predictions suggests that the seasonal performance of the downscaling tool is important and that a range of GCMs should be considered for water management planning.

Allen, D. M.; Cannon, A. J.; Toews, M. W.; Scibek, J.

2010-10-01

83

Aeolian dune field self-organization – implications for the formation of simple versus complex dune-field patterns  

Microsoft Academic Search

The interpretation of aeolian dune-field patterns as self-organizing complex systems is a new paradigm in which pattern evolution may be addressed. Computer simulations, supported by field and experimental data, indicate that a given wind regime produces a simple dune-field pattern. Dune type and crest orientation are determined by wind regime and pattern ordering occurs through dune–dune interactions over time. Because

Gary Kocurek; Ryan C. Ewing

2005-01-01

84

System for charging a rechargeable battery  

SciTech Connect

This patent describes, for use in an energy-using device adapted to operate from an external source of A-C power and from either rechargeable type or non-rechargeable type batteries of the same standard size and configuration, a charging system comprising in combination: a housing for the energy-using device. The energy-using device is operable in a first mode when connected to the external source of A-C power to supply the A-C power to a load disposed within the energy-using device and to recharge the rechargeable battery type and in a second mode when disconnected from the source of A-C power to supply power to the load alternatively from the rechargeable or non-rechargeable battery types; and electrical charging circuit disposed within the housing of the energy-using device for charging the rechargeable battery type when the energy-using device is connected to the external source of A-C power; and a cavity disposed within the housing of the energy-using device for alternatively receiving therein batteries of both of the rechargeable and non-rechargeable types. Each of the types has a positive power terminal and a negative power terminal for providing electrical energy from the battery types to the energy-using device.

Scholefield, C.L.

1986-12-09

85

Relation of hydrologic processes to groundwater and surface-water levels and flow directions in a dune-beach complex at Indiana Dunes National Lakeshore and Beverly Shores, Indiana  

USGS Publications Warehouse

The potential for high groundwater levels to cause wet basements (groundwater flooding) is of concern to residents of communities in northwestern Indiana. Changes in recharge from precipitation increases during 2006-9, water-level changes from restoration of nearby wetlands in the Great Marsh in 1998-2002, and changes in recharge due to the end of groundwater withdrawals for water supply since 2005 in a community at Beverly Shores, Ind., were suspected as factors in increased groundwater levels in an unconfined surficial aquifer beneath nearby parts of a dune-beach complex. Results of this study indicate that increased recharge from precipitation and snowmelt was the principal cause of raised water levels in the dune-beach complex from 2006 to 2009. Annual precipitation totals in 2006-9 ranged from 43.88 to 55.75 inches per year (in/yr) and were substantially greater than the median 1952-2009 precipitation of 36.35 in/yr. Recharge to groundwater from precipitation in 2006-9 ranged from 13.5 to 22 in/yr; it was higher than the typical 11 in/yr because of large precipitation events and precipitation amounts received during non-growing-season months. An estimated increase in net recharge from reduced groundwater use in Beverly Shores since 2005 ranged from 1.6 in/yr in 2006 to 1.9 in/yr in 2009. Surface-water levels in the wetland were as much as about 1.1 feet higher in 2007-9 (after the 1998-2002 wetland restoration) than during seasonally wet periods in 1979-89. Similar surface-water levels and ponded water were likely during winter and spring wet periods before and after wetland restoration. High water levels similar to those in 2009 were measured elsewhere in the dune-beach complex near a natural wetland during the spring months in 1991 and 1993 after receipt of near record precipitation. Recharge from similarly high precipitation amounts in 2008-9 was also a likely cause of high groundwater levels in other parts of the dune-beach complex, such as at Beverly Shores. Perennial mounding of the water table in the surficial aquifer indicates that the recharge that created the water-table mound originates within the dune-beach complex and not through flow from the adjacent hydrologic boundaries: the restored wetland, Lake Michigan, and Derby Ditch. Infiltrating precipitation causes most seasonal and episodic rises in groundwater levels beneath the dune-beach complex. Groundwater-level fluctuations lasting days to weeks in the dune-beach complex in 2008-9 were superimposed on a seasonal high water-table altitude that began with the recharge from snowmelt and rain in February 2009 and maintained through July 2009. Increases in water-table-mound altitude under the dune-beach complex recurred in 2008-9 in response to the largest rain events of 1 inch or more and to snowmelt. Smaller, shorter-term rises in water level after individual rain events persisted over hours to less than 1 week. Groundwater-level fluctuations varied over a relatively narrow range of about 2 to 3 feet, with no net fluctuations greater than 4 feet. Groundwater levels in or near low parts of the dune-beach complex were frequently within 0 to 6 feet of the land surface and indicate the potential for groundwater flooding. Groundwater-level gradients from the water-table mound to wells next to surface-water discharges increase after rainfall and snowmelt events and recede slowly as groundwater discharges from the aquifer. Evapotranspiration is responsible for part of the general pattern of decreasing water-table altitudes observed from May to August 2009. Rapid water-level rises in the restored wetland after precipitation do not likely have an effect on groundwater flooding elsewhere in the dune-beach complex. Surface-water-level fluctuations during this study generally varied over a narrower range, approximately from 1 to 1.5 feet, as compared with groundwater fluctuations, except after a very large, 10.77-inch rainfall. Time-delayed and smaller groundwater-level

Buszka, Paul M.; Cohen, David A.; Lampe, David C.; Pavlovic, Noel B.

2011-01-01

86

Identifying Recharge Location Using Noble Gas Recharge Temperatures, Pajarito Plateau, New Mexico  

NASA Astrophysics Data System (ADS)

The solubility of noble gases in water is temperature dependent. Noble gas concentrations in ground water can therefore be used to determine the temperature at the water table at the recharge location (recharge temperature). The Pajarito Plateau in Northern New Mexico is an example of a hydrogeologic setting where noble gas recharge temperatures provide valuable information about recharge location which could be utilized in numerical model calibration. Previous studies have identified two potentially significant components of recharge to the regional aquifer underlying the plateau: (1) infiltration of precipitation in the Jemez Mountains adjacent to the plateau (mountain-block recharge); and (2) infiltration of stream water in the bottoms of canyons that traverse the plateau (plateau recharge). However, results regarding the relative importance of these two components are conflicting and uncertain. Their relative magnitude is of particular concern because Los Alamos National Laboratory is located on the plateau, and the susceptibility of the regional aquifer to lab-generated wastes depends directly upon the amount of plateau recharge. The Pajarito Plateau is an ideal location for applying noble gas recharge thermometry; mountain-block recharge should have cool recharge temperatures (<12°C) due to the shallow water table in the mountains, whereas plateau recharge should have distinctly warmer recharge temperatures (18 to 21°C) due to water table depths of 200 to 300m on the plateau. Noble gas samples were collected from wells screened in the regional aquifer across the plateau. Those analyzed to date from wells screened in the upper 30m of the aquifer yield recharge temperatures of 18 to 23°C. Exceptions are two wells located within 2km of the mountain front, which have recharge temperatures of 12 and 13°C. The one sample analyzed to date from a well screened deeper in the aquifer (125m below the water table) yields a recharge temperature of 11°C. Preliminary results therefore suggest that plateau recharge comprises nearly all of the water in the upper 30m of the regional aquifer throughout much of the plateau. However, the cooler recharge temperatures closer to the mountains and at depth indicate that mountain-block recharge may still constitute most of the total recharge to the aquifer; plateau recharge may be limited to a thin layer along the top of the aquifer at distances >2km from the mountain front.

Manning, A. H.; Dale, M.

2008-12-01

87

Monitoring sand dune stabilization along the coastal dunes of Ashdod-Nizanim, Israel, 1945–1999  

Microsoft Academic Search

Temporal changes in the stabilization process along the coastal dunes of Israel were assessed using a series of 23 aerial photographs taken over the period 1944–1999. The stabilization rate was then quantified using a specially developed method for the calculation of sand dune movement and by the calibration of the gray-scale images into vegetation cover maps. An episodic reactivation of

N. Levin; E. Ben-Dor

2004-01-01

88

Dunes On Titan: Comparison Of The Fensal And Belet Dune Regions Using Multiple Datasets  

NASA Astrophysics Data System (ADS)

Titan's equatorial belt hosts large expanses of longitudinal dunes. As the Cassini mission continues, more of them are unveiled by the microwave RADAR, both in the active and passive modes and with an increasing number of viewing geometries. These observations have revealed some variations among dune regions. In particular, we find that the Belet and Fensal dune fields differ in terms of radar albedo and thermal emission. In this paper, we combine different datasets (SAR, radiometry, altimetry, scatterometry and SAR-derived topography) and compare them to an electromagnetic model in order to constrain the compositional and physical properties of the Belet and Fensal dunes. Differences between Fensal and Belet are well explained by various degrees of exposure of Titan's icy crust in the interdune regions (the troughs between the dunes). We find that a significant fraction of the Fensal interdunes must either be clear of sand, thus representing the dune substrate, or covered by icy gravels. This is consistent with VIMS spectra that show an enrichment in water ice in Fensal interdunes (Barnes et al., 2008). Furthermore, in many places in Fensal, dunes remain quite bright on SAR images suggesting that they are thin enough to allow waves to probe the substrate. Both interdune brightness and dune thinning point to the lack of available sediment supply in Fensal. In contrast, sand-sized particles seem abundant at Belet's location where the sand sheet is so thick that even the interdune flats appear radar-dark. The difference in sand supply between Fensal and Belet may be due to different wind regime and/or ground humidity. It may also be related to their respective emplacement: Belet is laying in a deep depression and Fensal dunes encroach on Sinlap's fresh water-ice ejecta blanket. The paper will discuss further the origin of the regional variations among Titan dunes.

Le Gall, Alice; Janssen, M. A.; Wye, L. C.; Hayes, A. G.; Lorenz, R. D.; Radebaugh, J.; Stiles, B.; Cassini RADAR Team

2010-10-01

89

Nearest neighbor methods applied to dune field organization: The Coral Pink Sand Dunes, Kane County, Utah, USA  

NASA Astrophysics Data System (ADS)

Dune fields have recently come to be recognized as self-organizing systems that can be seen progressing from states of disorganization or randomness to uniformity. Dune systems can be highly sensitive to changes in factors, such as climate and sediment transport, that determine system state. Changes in climate and sediment state can take time to work their way through a dune system; this, in turn, leads to spatial heterogeneity in dune field organization. Using the Coral Pink Sand Dunes in southern Utah as a model, this study tests nearest neighbor analysis adapted as a method to objectively identify and characterize differences in two dimensional dune patterns within a dune field and to identify changes in dune patterns over time. Reducing transverse and barchanoid dunes from linear to three-point features in planar space emphasizes the clustering that occurs when dune lengths and wavelengths are more disorganized or random. This clustering may be in response to a system perturbation, such as an influx of sediment, and is reflected in lower nearest neighbor index (R) values. As the system adjusts to the perturbation and moves towards steady state, dune length and spacing increase through migration and coalescing of smaller dunes; the resulting higher R values reflect this move towards greater uniformity in dune pattern. With the organizational states of dune systems recording feedback to changes in extrinsic climate and sediment factors, nearest neighbor analysis provides a proxy measure of system stability.

Wilkins, David E.; Ford, Richard L.

2007-01-01

90

NORTH CAROLINA GROUNDWATER RECHARGE RATES 1994  

EPA Science Inventory

North Carolina Groundwater Recharge Rates, from Heath, R.C., 1994, Ground-water recharge in North Carolina: North Carolina State University, as prepared for the NC Department of Environment, Health and Natural Resources (NC DEHNR) Division of Enviromental Management Groundwater S...

91

Reflections on Dry-Zone Recharge  

NASA Astrophysics Data System (ADS)

Quantifying recharge in regions of low precipitation remains a challenging task. The design of permanent nuclear-waste isolation at Yucca Mountain, Nevada, the design of arid-site landfill covers and the pumping of groundwater in desert cities, like Las Vegas, are examples where accurate recharge estimates are needed because they affect billion-dollar decisions. Recharge cannot be measured directly and must rely on estimation methods of various kinds including chemical tracers, thermal profiling, lysimetry, and water-balance modeling. Chemical methods, like chloride-mass-balance can significantly underestimate actual recharge rates and water-balance models are generally limited by large uncertainties. Studies at the U. S. Department of Energy's Hanford Site in Washington State, USA illustrate how estimates of recharge rates have changed over time and how these estimates can affect waste management decisions. Lysimetry has provided reliable estimates of recharge for a wide range of surface condittions. Lysimetric observations of reduced recharge, resulting from advective drying of coarse rock piles, suggest a way to avoid costly recharge protection using titanium shields at Yucca Mountain. The Pacific Northwest National Laboratory is funded by the U. S. Department of Energy under contract DE-AC05-76-RL01830.

Gee, G. W.

2005-05-01

92

Transformer Recharging with Alpha Channeling in Tokamaks  

SciTech Connect

Transformer recharging with lower hybrid waves in tokamaks can give low average auxiliary power if the resistivity is kept high enough during the radio frequency (rf) recharging stage. At the same time, operation in the hot ion mode via alpha channeling increases the effective fusion reactivity. This paper will address the extent to which these two large cost saving steps are compatible. __________________________________________________

N.J. Fisch

2009-12-21

93

Transformer Recharging with Alpha Channeling in Tokamaks.  

National Technical Information Service (NTIS)

Transformer recharging with lower hybrid waves in tokamaks can give low average auxiliary power if the resistivity is kept high enough during the radio frequency (rf) recharging stage. At the same time, operation in the hot ion mode via alpha channeling i...

N. J. Fisch

2009-01-01

94

Dunes on Titan observed by Cassini Radar  

NASA Astrophysics Data System (ADS)

Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ±30° of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions with topography, and correlation with other aeolian forms indicate a single, dominant wind direction aligned with the dune axis plus lesser, off-axis or seasonally alternating winds. Global compilations of dune orientations reveal the mean wind direction is dominantly eastwards, with regional and local variations where winds are diverted around topographically high features, such as mountain blocks or broad landforms. Global winds may carry sediments from high latitude regions to equatorial regions, where relatively drier conditions prevail, and the particles are reworked into dunes, perhaps on timescales of thousands to tens of thousands of years. On Titan, adequate sediment supply, sufficient wind, and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes.

Radebaugh, J.; Lorenz, R. D.; Lunine, J. I.; Wall, S. D.; Boubin, G.; Reffet, E.; Kirk, R. L.; Lopes, R. M.; Stofan, E. R.; Soderblom, L.; Allison, M.; Janssen, M.; Paillou, P.; Callahan, P.; Spencer, C.; the Cassini Radar Team

2008-04-01

95

Two modes of orientation for longitudinal dune deserts  

NASA Astrophysics Data System (ADS)

The shape of dunes depends mainly on wind regimes (alternate magnitude and direction of winds) and the availability of sand. In deserts where winds blow successively in two different directions, dunes are found to be long linear ridges. These linear dunes are the most common dunes on Earth. Indeed, the conditions to their formation are often met because of the succession between summer and winter winds in equatorial deserts, or between day and night winds in coastal deserts. The trend of linear dunes depends on the winds transport capacity and the angle between the two wind directions. When both winds have comparable magnitude and period, dunes are either perpendicular (transverse dunes) or parallel (longitudinal dunes) to the average sand transport direction, respectively for angles between winds smaller or bigger than 90°. When both winds have different magnitude and/or period, dunes orientation is found oblique to the average sand transport direction. Following the pioneering work of Rubin and Hunter, it is widely accepted that linear dune orientation maximizes the orthogonality between the structure and sand fluxes. However, we show in underwater experiments that oblique longitudinal dunes may have two different orientations, depending on the way they grow. These results suggest that in deserts subject to bimodal (and multimodal) wind regimes dune trends depend on initial and limit conditions. Finally, we show that the multiple dune orientations observed within a same field and sometimes on the same structure may not rely on a change of wind regime but can be explained by a unique wind regime.

Courrech du Pont, Sylvain; Narteau, Clément

2013-04-01

96

Mobile dunes and eroding salt marshes  

NASA Astrophysics Data System (ADS)

The paper deals with general outlines of salt marsh and dune vegetation in the Ellenbogen and Listland area on Sylt (Schleswig-Holstein, FRG). The composition of current salt marsh vegetation is considered to be mainly the result of a long-lasting process of tidal inundation, grazing, and a permanent influence of groundwater seepage from the surrounding dunes. The lower salt marsh communities have shown constancy for 67 years, due to the effect of heavy grazing. The mid-upper salt marsh communities demonstrated a succession from a Puccinellia maritima-dominated community of the lower marsh to a Juncus gerardii-dominated community of the mid-upper salt marsh, which may be due to the transport of sand — over a short time — on the surface of the marsh. The area covered by plant communities of annuals below Mean High Water (MHW) seemed to diminish. Salt marsh soils, especially of the mid-upper marsh, indicate sandy layers resulting from sand drift of the dunes. Dry and wet successional series of the dunes in the Listland/Ellenbogen area both show grassy stages shifting to dwarf shrubs as final stages. White primary dunes can only be found on the accreting shoreline of the Ellenbogen, which is also grazed by sheep; vegetation cover therefore remains dominated by grasses, mosses and lichens. Three mobile dunes (as the most prominent features of this landscape) have been left unaffected by seeding and planting by local authorities. Grazing is considered to be an inadequate tool in nature conservation as long as natural processes are to prevail in the landscape as major determinants.

Neuhaus, R.

1994-06-01

97

Linking restoration ecology with coastal dune restoration  

NASA Astrophysics Data System (ADS)

Restoration and preservation of coastal dunes is urgently needed because of the increasingly rapid loss and degradation of these ecosystems because of many human activities. These activities alter natural processes and coastal dynamics, eliminate topographic variability, fragment, degrade or eliminate habitats, reduce diversity and threaten endemic species. The actions of coastal dune restoration that are already taking place span contrasting activities that range from revegetating and stabilizing the mobile substrate, to removing plant cover and increasing substrate mobility. Our goal was to review how the relative progress of the actions of coastal dune restoration has been assessed, according to the ecosystem attributes outlined by the Society of Ecological Restoration: namely, integrity, health and sustainability and that are derived from the ecological theory of succession. We reviewed the peer reviewed literature published since 1988 that is listed in the ISI Web of Science journals as well as additional references, such as key books. We exclusively focused on large coastal dune systems (such as transgressive and parabolic dunefields) located on natural or seminatural coasts. We found 150 articles that included "coastal dune", "restoration" and "revegetation" in areas such as title, keywords and abstract. From these, 67 dealt specifically with coastal dune restoration. Most of the studies were performed in the USA, The Netherlands and South Africa, during the last two decades. Restoration success has been assessed directly and indirectly by measuring one or a few ecosystem variables. Some ecosystem attributes have been monitored more frequently (ecosystem integrity) than others (ecosystem health and sustainability). Finally, it is important to consider that ecological succession is a desirable approach in restoration actions. Natural dynamics and disturbances should be considered as part of the restored system, to improve ecosystem integrity, health and sustainability.

Lithgow, D.; Martínez, M. L.; Gallego-Fernández, J. B.; Hesp, P. A.; Flores, P.; Gachuz, S.; Rodríguez-Revelo, N.; Jiménez-Orocio, O.; Mendoza-González, G.; Álvarez-Molina, L. L.

2013-10-01

98

Mars global digital dune database and initial science results  

USGS Publications Warehouse

A new Mars Global Digital Dune Database (MGD3) constructed using Thermal Emission Imaging System (THEMIS) infrared (IR) images provides a comprehensive and quantitative view of the geographic distribution of moderate- to large-size dune fields (area >1 kM2) that will help researchers to understand global climatic and sedimentary processes that have shaped the surface of Mars. MGD3 extends from 65??N to 65??S latitude and includes ???550 dune fields, covering ???70,000 km2, with an estimated total volume of ???3,600 km3. This area, when combined with polar dune estimates, suggests moderate- to large-size dune field coverage on Mars may total ???800,000 km2, ???6 times less than the total areal estimate of ???5,000,000 km2 for terrestrial dunes. Where availability and quality of THEMIS visible (VIS) or Mars Orbiter Camera. narrow-angle (MOC NA) images allow, we classify dunes and include dune slipface measurements, which are derived from gross dune morphology and represent the prevailing wind direction at the last time of significant dune modification. For dunes located within craters, the azimuth from crater centroid to dune field centroid (referred to as dune centroid azimuth) is calculated and can provide an accurate method for tracking dune migration within smooth-floored craters. These indicators of wind direction are compared to output from a general circulation model (GCM). Dune centroid azimuth values generally correlate to regional wind patterns. Slipface orientations are less well correlated, suggesting that local topographic effects may play a larger role in dune orientation than regional winds. Copyright 2007 by the American Geophysical Union.

Hayward, R. K.; Mullins, K. F.; Fenton, L. K.; Hare, T. M.; Titus, T. N.; Bourke, M. C.; Colaprete, A.; Christensen, P. R.

2007-01-01

99

Do partially buried dune plants grow in optimal trajectories?  

Microsoft Academic Search

Plant adaptations minimising costs of burial responses are vital in mobile dune ecosystems. Conventionally, the burial responses\\u000a of dune plants have been measured as vertical growth. However, a model developed here shows that growth normal to accumulating\\u000a non-horizontal dune surfaces requires up to 18% less stem production than vertical growth. To determine whether dune plants\\u000a grow with this optimal geometry

M. E. Gilbert; N. W. Pammenter; B. S. Ripley

100

Lateral migration of linear dunes in the Strzelecki Desert, Australia  

USGS Publications Warehouse

Preferential accumulation of sand on east-facing flanks indicates that the dunes migrated eastward several metres during the Holocene. Moreover, the west-facing flanks of some dunes have experienced a minimum of tens of metres of erosion. This asymmetric erosion and deposition were caused by dune obliquity and lateral migration that may have begun as early as the Pleistocene. Dunes in the Strzelecki Desert and in the adjacent Simpson Desert display a variety of grossly different internal structures. -from Author

Rubin, D. M.

1990-01-01

101

Lithium ion rechargeable systems studies  

SciTech Connect

Lithium ion systems, although relatively new, have attracted much interest worldwide. Their high energy density, long cycle life and relative safety, compared with metallic lithium rechargeable systems, make them prime candidates for powering portable electronic equipment. Although lithium ion cells are presently used in a few consumer devices, e.g., portable phones, camcorders, and laptop computers, there is room for considerable improvement in their performance. Specific areas that need to be addressed include: (1) carbon anode--increase reversible capacity, and minimize passivation; (2) cathode--extend cycle life, improve rate capability, and increase capacity. There are several programs ongoing at Sandia National Laboratories which are investigating means of achieving the stated objectives in these specific areas. This paper will review these programs.

Levy, S.C.; Lasasse, R.R.; Cygan, R.T.; Voigt, J.A.

1995-02-01

102

Considerations for control of house construction in coastal dunes  

Microsoft Academic Search

This study was conducted to determine if maintenance of the integrity of coastal dunes as a form of storm protection should require restrictions on the types of buildings located within the dune zone. A properly built house does not appear to endanger the integrity of the dune to a point where the hazard potential is increased. Active human uses of

Karl F. Nordstrom; James M. McCluskey

1984-01-01

103

Restoration of an ancient dune system enhancing landscape perception  

Microsoft Academic Search

The Doñana National and Natural Parks (SW Spain) present two distinct substrates: the marshes, a silted-up former estuary, and the sands, a Pleistocene detritic formation of gravels, which has been repeatedly covered by dune mantles. The last historical dune-building period occurred during the Little Ice Age (XVI to XIX Centuries) with repeated pulses of dune advance and stability reaching to

Francisco García-Novo; Raquel Fernandez; Lo Faso; Daniel Garcia Sevilla

104

Sub-pixel habitat mapping of a costal dune ecosystem  

Microsoft Academic Search

Bare sand and semi-fixed dunes represent ideal conditions for successionally young slack habitats that support rare species of coastal dune flora. In ecologically significant and large dune systems, such as the Kenfig National Nature Reserve, UK, identification and mapping of favourable (sandy) and unfavourable (scrub-rich) habitats provide baseline information for conservation management. To map this habitat, spectral unmixing of airborne

Neil Stuart Lucas; Sanjeevi Shanmugam; Mike Barnsley

2002-01-01

105

Battery charging system including means for distinguishing between rechargeable and non-rechargeable batteries  

SciTech Connect

A battery charging system adapted to distinguish a rechargeable battery type from a non-rechargeable battery type is described, both types being of substantially similar size and having first and second external load terminals for delivering electrical energy. The system consists of: a battery charging circuit having a first non-charging mode and a second charging mode, the circuit having first and second charging contacts arranged for engagement with the first and second external load terminals respectively of when a battery is connected to the contacts; sensing means for sensing the value of at least one parameter common to both rechargeable and non-rechargeable batteries, the value for a rechargeable battery differing from the value for a non-rechangeable battery; enabling means responsive to the sensing means for disabling the charging circuit when the value is indicative of a non-rechargeable battery.

Hodgman, J.S.; Mullersman, F.H.

1986-03-18

106

Barchan dunes morphology dynamics under different environmental conditions  

NASA Astrophysics Data System (ADS)

The aim of this study was to emphasize significance of diversified dynamics of barchans dune morphology. We analyzed and compared barchans found in two dune fields: Kharga (S Egypt) and Tarfaya-Laâyoune (S-Morocco). These dune fields are characterized by significantly different factors responsible for dunes development e.g. textural and mineralogical composition of dune sand, dune sand moisture, air humidity, inter dune vegetation cover. For each investigated dune filed and study period (2008, 2010, 2012 for Kharga and 2007, 2011, 2012 for Tarfaya-Laâyoune dune fields) detailed shape measurement of 20 simple isolated barchans of different dune sizes was made. The ± 10-2 m horizontal and ± 1,5 10-2m vertical accuracy was obtained (1 measuring point per 1m2 on average).In order to compare barchan dunes morphology and to determine depositional and erosional patterns, the 3D models were created. For better understanding of this processes, sand bulk density of barchan surface was measured (1 measuring point per 2m2 on average). The velocity of dunes in relation to dune shape was also analyzed. The results show that the relationship between typically correlated parameters change during movement of the barchans. Most values change by a few percent per year (slip face height, dune base area and dune volume) or by a dozen or so percent per year (windward side length, horns length and width). We obtain good linear relationship (with 0,05 significant level) between slip face height and the dune base area (0,77 < R2 < 0,83), dune volume (0,66 < R2 < 0,72), windward side length (0,58 < R2 < 0,87), horns length (0,71 < R2 < 0,90) or horns width (0,79 < R2 < 0,93). The linear relationship between displacement rate and the morphological parameters is not strong (0,54< R2 < 0,81) for Kharga dune field and (0,41< R2 < 0,66) for Tarfaya-Laâyoune dune field. We noted also good linear relationship between displacement rate and the angle of span of the horns (R2=0,73 on Tarfaya-Laâyoune dune fields). Comparison of shape change of the same barchan made it possible to determine the depositional and erosional zones. The annual changes of surface altitude do not exceed a few percent of the total sand thickness in analyzed zones (more for small dunes). However, we noted important shape differences between barchans of the same slip face height in two investigated dune fields (up to 20% of sand thickness in the same point). We also found a good correlation between barchans shape and bulk density of dune sand. The highest bulk density of the dune sand is noted at the dune horns (up to 1767kg m-3 for Kharga dune field and up to 1644 kg m-3 for Tarfaya-Laâyoune dune field). On the windward (stoss) sides the bulk density of the dune sand depends on barchans shape (slope inclination). The lee sides have the value around 1400 kg m-3. Generally our result show relatively small differences in dune morphology dynamics within the same dune field but much greater between the two analyzed areas.

Dluzewski, M.

2012-04-01

107

Beaches, Dunes, and Barrier Islands. Habitat Pac.  

ERIC Educational Resources Information Center

The materials in this educational packet are designed for use with students in grades 4 through 7. They consist of a leader overview, teaching guides and student data sheets for three activities, and a poster. The leader overview describes the nature of beaches, dunes, and barrier islands, tracing their development, settlement, and management and…

Fish and Wildlife Service (Dept. of Interior), Washington, DC.

108

Secondary dune succession on Inhaca Island, Mozambique  

Microsoft Academic Search

Old field succession was studied on coastal dunes supporting tropical evergreen forest on Inhaca Island, Mozambique. Plots of 10×10 m were sited in three early successional stages and in relatively undisturbed forest. Woody species increased in number during succession; leptophylls were most frequent in younger vegetation, whereas microphylls and mesophylls were most frequent in forest. Grasses, shrubs and forbs dominated

B. M. Campbell; C. A. M. Attwell; J. C. Hatton; P. de Jager; J. Gambiza; T. Lynam; F. Mizutani; P. Wynter

1988-01-01

109

Probabilistic assessment of beach and dune changes  

USGS Publications Warehouse

The recent availability of spatially-dense airborne lidar data makes assessment of the vulnerability of beaches and dunes to storm impacts practical over long reaches of coast. As an initial test, elevations of the tops (D high) and bases (Dlow) of foredune ridges along a 55-km reach on the northern Outer Banks, NC were found to have considerable spatial variability suggesting that different parts of the barrier island would respond differently to storms. Comparing statistics of storm wave runup to D high and Dlow, we found that net erosion due to overwash and dune retreat should be greatest at the northern and southern ends of the study area and least in the central section. This predicted spatial pattern of storm-induced erosion is similar to the spatial pattern of long-term erosion of the shoreline which may be controlled by additional processes (such as gradients in longshore transport) as well as the cross-shore processes considered here. However, consider feedback where at erosional hot spots there is a deficit of sand (caused by gradients in longshore transport) which lead to lower dunes and enhanced erosional cross-shore processes, such as overwash. Hence, the erosional hot spots would be exacerbated, further increasing the vulnerability of the beach and dunes to net erosion.

Sallenger, Jr. , A. H.; Stockdon, H.; Haines, J.; Krabill, W.; Swift, R.; Brock, J.

2004-01-01

110

Coastal aeolian dune development, Sólheimasandur, southern Iceland  

Microsoft Academic Search

A coastal aeolian dune field on the distal parts of Sólheimasandur, southern Iceland is currently undergoing active construction. Ongoing sand deflation in the foreshore is demonstrated by the preservation of sand ridges in the downwind lee of obstacles, while a backshore sandsheet is characterised by actively accumulating long-wavelength wind ripples. The main region of aeolian accumulation is in the immediate

Nigel P. Mountney; Andrew J. Russell

2006-01-01

111

Experimental studies in natural groundwater-recharge dynamics: The analysis of observed recharge events  

Microsoft Academic Search

Sophocleous, M. and Perry, C.A., 1985. Experimental studies in natural groundwater- recharge dynamics: The analysis of observed recharge events. J. Hydrol., 81 : 297--332. The amounts and time distribution of groundwater recharge from precipitation over an approximately 19-month period were investigated at two instrumented sites in south- central Kansas. Precipitation and evapotranspiration sequences, soil-moisture profiles and storage changes, water fluxes

MARIOS SOPHOCLEOUS; CHARLES A. PERRY

1985-01-01

112

Origin of terrestrial gypsum dunes—Implications for Martian gypsum-rich dunes of Olympia Undae  

Microsoft Academic Search

The Estancia, White Sands, Guadalupe and Cuatrociénegas Dune Fields are among the largest known aeolian gypsum sand-dune accumulations on Earth and occupy closed-drainage basins within the Rio Grande Rift. High sedimentation rates of lacustrine gypsum occur in topographic depressions within the closed basins. The gypsum accumulations result from long-term, complex, interaction between tectonism, climate, and a hydrologic cycle that involves

Anna Szynkiewicz; Ryan C. Ewing; Craig H. Moore; Mihaela Glamoclija; David Bustos; Lisa M. Pratt

2010-01-01

113

Development of spatially diverse and complex dune-field patterns: Gran Desierto Dune Field, Sonora, Mexico  

USGS Publications Warehouse

The pattern of dunes within the Gran Desierto of Sonora, Mexico, is both spatially diverse and complex. Identification of the pattern components from remote-sensing images, combined with statistical analysis of their measured parameters demonstrate that the composite pattern consists of separate populations of simple dune patterns. Age-bracketing by optically stimulated luminescence (OSL) indicates that the simple patterns represent relatively short-lived aeolian constructional events since ???25 ka. The simple dune patterns consist of: (i) late Pleistocene relict linear dunes; (ii) degraded crescentic dunes formed at ???12 ka; (iii) early Holocene western crescentic dunes; (iv) eastern crescentic dunes emplaced at ???7 ka; and (v) star dunes formed during the last 3 ka. Recognition of the simple patterns and their ages allows for the geomorphic backstripping of the composite pattern. Palaeowind reconstructions, based upon the rule of gross bedform-normal transport, are largely in agreement with regional proxy data. The sediment state over time for the Gran Desierto is one in which the sediment supply for aeolian constructional events is derived from previously stored sediment (Ancestral Colorado River sediment), and contemporaneous influx from the lower Colorado River valley and coastal influx from the Bahia del Adair inlet. Aeolian constructional events are triggered by climatic shifts to greater aridity, changes in the wind regime, and the development of a sediment supply. The rate of geomorphic change within the Gran Desierto is significantly greater than the rate of subsidence and burial of the accumulation surface upon which it rests. ?? 2006 The Authors. Journal compilation 2006 International Association of Sedimentologists.

Beveridge, C.; Kocurek, G.; Ewing, R. C.; Lancaster, N.; Morthekai, P.; Singhvi, A. K.; Mahan, S. A.

2006-01-01

114

REVISED NORTH CAROLINA GROUNDWATER RECHARGE RATES 1998  

EPA Science Inventory

Revised North Carolina Groundwater Recharge Rates, from Heath, R.C., 1994, unpublished map: North Carolina State University, as modified by the NC Department of Environment and Natural Resources (DENR) Division of Water Quality (DWQ) Groundwater Section, (polygons)...

115

Organic Pollutants in Ground-Recharged Water.  

National Technical Information Service (NTIS)

The objective of this project was to determine the identities of the haloforms (THMs) in ground recharged water as well as the concentrations and identities of the haloform precursors (THMPs). A second objective was the determination of these compounds in...

C. Steelink H. Bohn M. A. Mikita K. Thorn J. Hobson

1981-01-01

116

Identifying and quantifying urban recharge: a review  

NASA Astrophysics Data System (ADS)

The sources of and pathways for groundwater recharge in urban areas are more numerous and complex than in rural environments. Buildings, roads, and other surface infrastructure combine with man-made drainage networks to change the pathways for precipitation. Some direct recharge is lost, but additional recharge can occur from storm drainage systems. Large amounts of water are imported into most cities for supply, distributed through underground pipes, and collected again in sewers or septic tanks. The leaks from these pipe networks often provide substantial recharge. Sources of recharge in urban areas are identified through piezometry, chemical signatures, and water balances. All three approaches have problems. Recharge is quantified either by individual components (direct recharge, water-mains leakage, septic tanks, etc.) or holistically. Working with individual components requires large amounts of data, much of which is uncertain and is likely to lead to large uncertainties in the final result. Recommended holistic approaches include the use of groundwater modelling and solute balances, where various types of data are integrated. Urban recharge remains an under-researched topic, with few high-quality case studies reported in the literature. Résumé. Les origines et les trajets de la recharge des nappes en zones urbaines sont plus nombreux et plus complexes qu'en zones rurales. Les bâtiments, les routes et les autres infrastructures de surface se combinent avec les réseaux de drainage artificiels en modifiant les voies d'écoulements des précipitations. Une partie de la recharge directe est perdue, mais une recharge supplémentaire peut intervenir à partir des systèmes de drainage d'eaux pluviales. Des quantités importantes d'eau sont importées dans la plupart des villes pour l'alimentation, sont distribuées par des conduites souterraines et sont collectées dans des égouts ou des fosses septiques. Les fuites de ces réseaux de conduites constituent souvent une part importante de la recharge. L'origine de la recharge en zones urbaines est mise en évidence grâce à la piézométrie, aux signatures chimiques et aux bilans hydrologiques. Ces trois approches posent des problèmes. La recharge est quantifiée soit à partir de ses composantes individuelles (la recharge directe, les fuites d'eaux des réseaux, les fosses septiques, etc.), soit de façon globale. Pour travailler avec les composantes individuelles, il faut de grandes quantités de données, dont beaucoup comportent des incertitudes, et le résultat final présentera vraisemblablement des incertitudes importantes. Les approches globales recommandées s'appuient sur la modélisation de l'aquifère et les bilans de solutés, dans lesquels différents types de données sont intégrés. La recharge en zone urbaine reste un sujet délaissé par la recherche, offrant dans la littérature peu d'études de cas de bonne qualité. Resumen. Las fuentes y vías de recarga en zonas urbanas son más numerosas y complejas que en medios rurales. Los edificios, carreteras y otras infraestructuras superficiales se combinan con las obras antrópicas de drenaje para modificar las vías de infiltración. Una parte de la recarga directa se pierde, pero puede haber contribuciones adicionales a partir de los sistemas de drenaje de aguas pluviales. Se importa grandes volúmenes de agua a la mayoría de las ciudades para abastecimiento, siendo distribuida por medio de tuberías subterráneas, y recogida de nuevo en alcantarillas o fosas sépticas. Las pérdidas en las redes de distribución a menudo aportan una recarga substancial. Las fuentes de recarga en zonas urbanas se identifican mediante la piezometría, trazadores químicos y balances de agua, pero los tres métodos presentan problemas. La recarga se cuantifica bien por sus componentes individuales (recarga directa, goteo en tuberías, fosas sépticas, etc.) o bien de forma holística. La primera opción requiere muchos datos, a menudo inciertos, y es probable que se obtengan enormes incertidumbres en el resultado fin

Lerner, David

2002-01-01

117

Rechargeable thin-film lithium batteries.  

National Technical Information Service (NTIS)

Rechargeable thin-film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have recently been developed. The batteries, which are typically less than 6-(mu)m thick, can be fabri...

J. B. Bates G. R. Gruzalski N. J. Dudney C. F. Luck X. Yu

1993-01-01

118

Method of Recharging Fire Extinguisher Bottles.  

National Technical Information Service (NTIS)

This invention relates to a method of recharging fire extinguisher bottles wherein special transfer cylindrs are used to store and discharge predetermined quantities of liquid fire suppressant and pressurizing gas to the bottle. The process is carried out...

A. J. Monte

1980-01-01

119

Rechargeable manganese oxide batteries. (Genopladelige manganoxid batterier).  

National Technical Information Service (NTIS)

Former work on lithium and sodium batteries proved the feasibility of making solid state cells with high energy density and reversibility. The utility of manganese oxides as cathode material in rechargeable alkali metal solid state intercalation batteries...

B. Zachau-Christensen K. West S. Skaarup

1992-01-01

120

Methods for Fabricating Lithium Rechargeable Batteries.  

National Technical Information Service (NTIS)

There are provided novel methods of fabricating batteries, particularly rechargeable lithium ion batteries comprising a microporous polymeric gel layer on one or more electrodes of the batteries. The methods include laminating a gellable polymer film to a...

B. Oh K. Amine

2005-01-01

121

Recharging the Ogallala Formation Using Shallow Holes.  

National Technical Information Service (NTIS)

Natural groundwater recharge cannot sustain the Southern High Plains portion of the Ogallala Formation. Nearly all the water used in this region is derived from the Ogallala Formation. The southern part of the Ogallala is hydrologically isolated from all ...

M. J. Dvoracek S. H. Peterson

1970-01-01

122

Issues and challenges facing rechargeable lithium batteries  

Microsoft Academic Search

Technological improvements in rechargeable solid-state batteries are being driven by an ever-increasing demand for portable electronic devices. Lithium-ion batteries are the systems of choice, offering high energy density, flexible and lightweight design, and longer lifespan than comparable battery technologies. We present a brief historical review of the development of lithium-based rechargeable batteries, highlight ongoing research strategies, and discuss the challenges

J.-M. Tarascon; M. Armand

2001-01-01

123

Conductivity of electrolytes for rechargeable lithium batteries  

NASA Astrophysics Data System (ADS)

The conductivity of 150 nonaqueous electrolytes for rechargeable Li batteries between -60 and 80 C is reported. A wide range of solvents including esters, ethers, aromatics, chlorinated solvents, etc., and mixtures thereof, were studied. Results for five electrolyte salts which have some promise for rechargeable Li cells are presented. Several of the trends in the data are discussed, and the importance of solvent viscosity in determining electrolyte conductivity is shown.

Dudley, J. T.; Wilkinson, D. P.; Thomas, G.; Levae, R.; Woo, S.

1991-06-01

124

System for charging a rechargeable battery  

Microsoft Academic Search

This patent describes, for use in an energy-using device adapted to operate from an external source of A-C power and from either rechargeable type or non-rechargeable type batteries of the same standard size and configuration, a charging system comprising in combination: a housing for the energy-using device. The energy-using device is operable in a first mode when connected to the

Scholefield

1986-01-01

125

Geomorphology of coastal sand dunes, Baldwin County, Alabama  

USGS Publications Warehouse

Alabama's coastal eolian deposits are primarily vegetated dunes that are exemplified by sand ridges with flat to undulating upper surfaces and continuous irregular crests. Dune fields occur along Morgan peninsula between the foredune line and Little Lagoon and the Mobile Bay area. These dune fields consist primarily of one or more continuous ridges that parallel the coast and are generally vegetaed to grassy. Washover of the beach and backshore during Hurricane Frederic (1979) and subsequent smaller scale storms resulted in significant erosion of many of Alabama's dune fields. The primary dunes or foredunes are beginning to recover from the effects of these storms; however, numerous breaks in the primary dune line are present. Sand dunes in coastal Alabama provide protection against storm-generated waves and washover. The foredunes are protected by adherence to a Coastal Construction Control Line (CCCL) or construction setback line identified by markers along coastal Baldwin County.

Bearden, Bennett, L.; Hummell, Richard, L.; Mink, Robert, M.

1989-01-01

126

Seasonal erosion and restoration of Mars' northern polar dunes.  

PubMed

Despite radically different environmental conditions, terrestrial and martian dunes bear a strong resemblance, indicating that the basic processes of saltation and grainfall (sand avalanching down the dune slipface) operate on both worlds. Here, we show that martian dunes are subject to an additional modification process not found on Earth: springtime sublimation of Mars' CO(2) seasonal polar caps. Numerous dunes in Mars' north polar region have experienced morphological changes within a Mars year, detected in images acquired by the High-Resolution Imaging Science Experiment on the Mars Reconnaissance Orbiter. Dunes show new alcoves, gullies, and dune apron extension. This is followed by remobilization of the fresh deposits by the wind, forming ripples and erasing gullies. The widespread nature of these rapid changes, and the pristine appearance of most dunes in the area, implicates active sand transport in the vast polar erg in Mars' current climate. PMID:21292976

Hansen, C J; Bourke, M; Bridges, N T; Byrne, S; Colon, C; Diniega, S; Dundas, C; Herkenhoff, K; McEwen, A; Mellon, M; Portyankina, G; Thomas, N

2011-02-01

127

Seasonal Erosion and Restoration of Mars’ Northern Polar Dunes  

NASA Astrophysics Data System (ADS)

Despite radically different environmental conditions, terrestrial and martian dunes bear a strong resemblance, indicating that the basic processes of saltation and grainfall (sand avalanching down the dune slipface) operate on both worlds. Here, we show that martian dunes are subject to an additional modification process not found on Earth: springtime sublimation of Mars’ CO2 seasonal polar caps. Numerous dunes in Mars’ north polar region have experienced morphological changes within a Mars year, detected in images acquired by the High-Resolution Imaging Science Experiment on the Mars Reconnaissance Orbiter. Dunes show new alcoves, gullies, and dune apron extension. This is followed by remobilization of the fresh deposits by the wind, forming ripples and erasing gullies. The widespread nature of these rapid changes, and the pristine appearance of most dunes in the area, implicates active sand transport in the vast polar erg in Mars’ current climate.

Hansen, C. J.; Bourke, M.; Bridges, N. T.; Byrne, S.; Colon, C.; Diniega, S.; Dundas, C.; Herkenhoff, K.; McEwen, A.; Mellon, M.; Portyankina, G.; Thomas, N.

2011-02-01

128

Seasonal erosion and restoration of Mars' northern polar dunes  

USGS Publications Warehouse

Despite radically different environmental conditions, terrestrial and martian dunes bear a strong resemblance, indicating that the basic processes of saltation and grainfall (sand avalanching down the dune slipface) operate on both worlds. Here, we show that martian dunes are subject to an additional modification process not found on Earth: springtime sublimation of Mars' CO 2 seasonal polar caps. Numerous dunes in Mars' north polar region have experienced morphological changes within a Mars year, detected in images acquired by the High-Resolution Imaging Science Experiment on the Mars Reconnaissance Orbiter. Dunes show new alcoves, gullies, and dune apron extension. This is followed by remobilization of the fresh deposits by the wind, forming ripples and erasing gullies. The widespread nature of these rapid changes, and the pristine appearance of most dunes in the area, implicates active sand transport in the vast polar erg in Mars' current climate.

Hansen, C. J.; Bourke, M.; Bridges, N. T.; Byrne, S.; Colon, C.; Diniega, S.; Dundas, C.; Herkenhoff, K.; McEwen, A.; Mellon, M.; Portyankina, G.; Thomas, N.

2011-01-01

129

Changes of Bulgarian Coastal Dune Landscape under Anthropogenic Impact  

NASA Astrophysics Data System (ADS)

At one time large sand dune formations were widely distributed along the Bulgarian coast. However, due to increased urbanization in the coastal zone, the areas of total dune landscape has been constantly reduced. Dunes presently comprise only 10% of the entire 412 km long coastline of Bulgaria: they embrace a total length of 38.57 km and a total area of 8.78 km2 Important tasks in dune protection are identification of landscape changes for a certain period of time and accurate delineation of sand dune areas. The present research traces sand dune changes along the Bulgarian Black Sea coast over a 27 year period (1983-2010). This period includes also the time of expanded tourist boom and overbuilding of the coastal zone, and respectively presents the largest dune changes and reductions. Based on the landscape change analyst in GIS environment the study also aims to explore the importance of different natural and human factors in driving the observed dune alterations and destruction. To detect and assess dune changes during the last 3 decades, we used data for sand dunes derived from several sources at different time periods in order to compare changes in shoreline positions, dune contours and areas: i) Topographic maps in 1:5,000 scale from 1983; ii) Modern Very High Resolution orthophotographs from 2006 and 2010; iii) QuickBird Very High Resolution satellite images from 2009; iv) Statistical information for population and tourist infrastructure is also used to consider the influence of human pressure and hotel developments on the dune dynamics. In addition, for more detailed description and visualization of main dune types, digital photos have been taken at many parts of the Bulgarian coast. The study was performed in GIS environment. Based on the results obtained the dunes along the Bulgarian coast were divided into three main groups with relation to the general factors responsible for their alterations: i) Dunes that have decreased in result of shoreline retreat and erosion of the beach itself. Typically dunes are located behind sand beaches and they are part of the beach-dune systems. Such type of dune reduction could be driven by combination of many factors, both natural ones (such as severe storms, erosion, heavy rains or flooding) and human impacts (large number of installed coast-protection structures along the coast, which interrupt the sediment transport, create new sedimentary deficit and generate erosion). During the recent years most of the Bulgarian beaches have progressively eroded and their areas have significantly been decreased. ii) Dunes that have been reduced/damaged and lost due to expanded tourist and housing infrastructures/developments and due to afforestaion activities. The principal sources of human impacts on sand dunes in Bulgaria are rapid coastal urbanization over the recent years (i.e., hotel and residential constructions, roads, parking structures, and other related infrastructure), unregulated camping and "temporary" constructions on the dunes, a lax regulatory environment that tolerates the re-zoning of protected sand dunes to "agricultural" areas. At most recreational sites there were wide coastal dunes, which however have been destroyed during tourist constructions. Such are dunes at the most famous Bulgarian sea resorts of Golden Sands and Sunny Beach in the areas of Varna and Nessebar. As a consequence, major areas along the Bulgarian coast were completely urbanized by hotels and other infrastructures and large sand dune systems were damaged. iii) Dunes located at still undeveloped coastal sections: yet they are naturally preserved and unthreatened by human pressure boom. These are just a few dune sites: at the northernmost portion of the Bulgarian coast (in the area of Durankulak), at the central part in the region of the largest Bulgarian river, Kamchia River, and along the southernmost coastline (in the area of Veleka River). Although sand dunes in Bulgaria are protected areas and national reserves they have been exposed to large anthropogenic pressure in particu

Palazov, A.; Young, R.; Stancheva, M.; Stanchev, H.

2012-04-01

130

Proposed artificial recharge studies in northern Qatar  

USGS Publications Warehouse

The aquifer system in northern Qatar comprises a water-table aquifer in the Rus Formation which is separated by an aquitard from a partially confined aquifer in the top of the overlying Umm er Radhuma Formation. These two aquifers are composed of limestone and dolomite of Eocene and Paleocene age and contain a fragile lens of freshwater which is heavily exploited as a source of water for agricultural irrigation. Net withdrawals are greatly in excess of total recharge, and quality of ground water is declining. Use of desalinated seawater for artificial recharge has been proposed for the area. Artificial recharge, on a large scale, could stabilize the decline in ground-water quality while allowing increased withdrawals for irrigation. The proposal appears technically feasible. Recharge should be by injection to the Umm er Radhuma aquifer whose average transmissivity is about 2,000 meters squared per day (as compared to an average of about 200 meters squared per day for the Rus aquifer). Implementation of artificial recharge should be preceded by a hydrogeologic appraisal. These studies should include test drilling, conventional aquifer tests, and recharge-recovery tests at four sites in northern Qatar. (USGS)

Kimrey, J. O.

1985-01-01

131

Battery charging system including means for distinguishing between rechargeable and non-rechargeable batteries  

Microsoft Academic Search

A battery charging system adapted to distinguish a rechargeable battery type from a non-rechargeable battery type is described, both types being of substantially similar size and having first and second external load terminals for delivering electrical energy. The system consists of: a battery charging circuit having a first non-charging mode and a second charging mode, the circuit having first and

J. S. Hodgman; F. H. Mullersman

1986-01-01

132

Migration of parabolic dunes at Aberffraw, Anglesey, north Wales  

NASA Astrophysics Data System (ADS)

Aberffraw is a 1-km-wide and 3-km-long transgressive dunefield that extends inland along a northeast-southwest-trending valley from a southwest-facing beach, Traeth Mawr. The prevailing wind is from the southwest, and both the parabolic dunes and the valley within which they lie are sub-parallel to the prevailing wind. The dunefield at Aberffraw includes two foredune ridges and three rows of active compound parabolic dunes. At the landward end is a lake, Llyn Coron, which has been formed by dunes migrating up the valley and damming the river, Afon Ffraw. Between the parabolic dunes are gently sloping interdune areas with a close cropped vegetation. The parabolic dunes at Aberffraw have been migrating inland across the interdune areas. Rates of parabolic dune migration are derived from three sets of aerial photographs taken in 1940, 1982 and 1993. The aerial photographs have been scanned and manipulated in ArcView GIS software. Registration of the aerial photograph to an Ordnance Survey (OS) map was performed using ground control points (GCPs), common fixed features that are identifiable on both the aerial photographs and the baseline map. Attempts to correct for the inherent distortions of aerial photography were made during registration. Standardising the projection of the photographs to a common baseline allows meaningful spatial analysis, and the dune ridges, trailing edges and areas of bare sand were mapped from each photograph as a series of overlays. Rates of dune migration are calculated from the spatial distance between linear trend lines, parallel to the dune crests and perpendicular to the dune migration orientation, applied to sections of dune ridges for 1940 and 1993. Trend lines were only fitted to sections where continuity of dune form was maintained over the given period. The method provides an improved representation of the actual migration rate as it incorporates the whole of the parabolic dune form, and the whole of the compound dune ridge form into the calculation. It effectively measures the centre point or line of a dune or dune ridge as opposed to the variable positions and orientations of the dune crest noses, which represent maximum migration, rather than the mean. Rates of parabolic dune migration range from a minimum of 0 m year -1 to a maximum of 3.6 m year -1, with an average migration rate of 1 m year -1.

Bailey, S. D.; Bristow, C. S.

2004-04-01

133

Barchan dune asymmetry: Observations from Mars and Earth  

NASA Astrophysics Data System (ADS)

Barchan dune asymmetry refers to the extension of one barchan limb downwind. It is a common dune form on Earth and also occurs on Mars and Titan. A new classification of barchan limbs is presented where three types of limb morphology are identified: linear, kinked and beaded. These, along with other dune-scale morphological signatures, are used to identify three of the causes of barchan asymmetry on Mars: bi-directional winds, dune collision and the influence of inclined topography. The potential for specific dune asymmetric morphologies to indicate aspects of the formative wind regime on planetary surfaces is shown. For example, the placement of dune limbs can indicate the general direction and relative strength of formative oblique winds; an extreme barchan limb length may indicate a long duration oblique wind; a kinked limb may be evidence of the passage of a storm; beaded limbs may represent surface-wave instabilities caused by an increase in wind energy parallel to the dune. A preliminary application of these signatures finds evidence for bi-modal winds on Mars. However, these and other morphological signatures of wind direction and relative strength should be applied to planetary landforms with caution as more than one process (e.g., bi-modal winds and collision) may be operating together or sequentially on the dunefield. In addition, analysis should be undertaken at the dunefield scale and not on individual dunes. Finally, morphological data should be acquired from similar-scale dunes within a dunefield. In addition to bi-modal wind regimes on Mars, the frequent parallel alignment of the extended barchan limb to the dune suggests that dune collision is also an important cause of asymmetry on Mars. Some of the more complex dunefield patterns result from a combination of dune collision, limb extension and merging with downwind dunes. Dune asymmetric form does not inhibit dune migration in the Namib Desert or on Mars. Data from the Namib suggest that dune migration rates are similar for symmetric and asymmetric dunes. Further modeling and field studies are needed to refine our understanding of the potential range of limb and dune morphologies that can result from specific asymmetry causes.

Bourke, Mary C.

2010-01-01

134

Great Kobuk Sand Dunes, Alaska: A Terrestrial Analog Site for Polar, Topographically Confined Martian Dune Fields  

NASA Astrophysics Data System (ADS)

Martian dune systems belong to two broad categories: (i) the sprawling north polar erg, rich in and immobilized by seasonal and perennial volatiles; and (ii) isolated low- to high-latitude dune fields confined by topography. While modern dune migration on Mars is nearly imperceptibly slow, recent studies are producing robust evidence for aeolian activity, including bedform modification. Cold-climate terrestrial dunes containing volatile reservoirs provide an important analog to Martian polar dunes because permafrost and seasonal cycles of CO2 and H2O frost mantling are thought to partially decouple Martian polar dunes from atmospheric forcing. The 67°N latitude, 62 km2 Great Kobuk Sand Dunes (GKSD) are a terrestrial analog for polar, intercrater dune fields on Mars. Formative winds affected by complex topography and the presence of volatiles and intercalated snow within the GKSD have direct analogy to factors that impede migration of Martian polar dunes. This system offers the opportunity to study cold-climate, noncoastal, topographically constrained, climbing and reversing barchanoid, transverse, longitudinal, and star dunes. The Kobuk Valley climate is subarctic and semiarid with long, cold winters and brief, warm summers. Niveoaeolian sedimentation occurs within west-facing lee slope catchments. In March 2010, we found the seasonally frozen layer to range in thickness from 1.5 to 4.0 m, and no evidence for shallow permafrost. Instead, using GPR and boreholes, we found a system-wide groundwater aquifer that nearly parallels topography and cuts across steeply dipping bedforms. GPR cannot uniquely detect ice and water; however, a similar analysis of rover-based GPR might be used to detect volatiles in Martian dunes. The perennial volatile reservoir is liquid because of mean annual air temperature, intense solar heating before, during, and after 38 days of continuous summer daylight, high dry sand thermal conductivity, higher wet sand thermal conductivity, infiltration of relatively warm summer precipitation, and the insulative properties of longlived snowcover. We hypothesize that the seasonally frozen layer and niveoaeolian deposits combined with a shallow aqueous reservoir are responsible for the low migration rate of the GKSD (i.e., ~1.3 m/yr over a recent 5-year period). Just as migration of the GKSD is affected by partial to full snowcover for 70% of the year, Martian polar dunes are affected by partial to full frost mantling for 70% of the year, significantly limiting the duration of aeolian transport. Thin water films surrounding sand grains at the GKSD make moist sand cohesive and structurally stable, like a solid. The partially saturated sand above the capillary fringe of an unconfined aquifer in the GKSD will limit sand available for aeolian transport, potentially similar to effects of permafrost within a Martian dune. We will present our geophysical, geomorphologic, and meteorologic field data and modeling analyses.

Dinwiddie, C. L.; Hooper, D. M.; Michaels, T. I.; McGinnis, R. N.; Stillman, D.; Bjella, K.; Stothoff, S.; Walter, G. R.; Necsoiu, M.; Grimm, R. E.

2010-12-01

135

Annual monsoon rains recorded by Jurassic dunes.  

PubMed

Pangaea, the largest landmass in the Earth's history, was nearly bisected by the Equator during the late Palaeozoic and early Mesozoic eras. Modelling experiments and stratigraphic studies have suggested that the supercontinent generated a monsoonal atmospheric circulation that led to extreme seasonality, but direct evidence for annual rainfall periodicity has been lacking. In the Mesozoic era, about 190 million years ago, thick deposits of wind-blown sand accumulated in dunes of a vast, low-latitude desert at Pangaea's western margin. These deposits are now situated in the southwestern USA. Here we analyse slump masses in the annual depositional cycles within these deposits, which have been described for some outcrops of the Navajo Sandstone. Twenty-four slumps, which were generated by heavy rainfall, appear within one interval representing 36 years of dune migration. We interpret the positions of 20 of these masses to indicate slumping during summer monsoon rains, with the other four having been the result of winter storms. The slumped lee faces of these Jurassic dunes therefore represent a prehistoric record of yearly rain events. PMID:11452305

Loope, D B; Rowe, C M; Joeckel, R M

2001-07-01

136

Global map of Titan's dune fields  

NASA Astrophysics Data System (ADS)

Introduction Methane is the second major constituent of Titan's atmosphere; but it should be totally removed at least in ten million years by photochemistry in the stratosphere and condensation in the troposphere [1]. The first process produces hydrocarbons which form the haze and can condensate onto the surface. The second process causes methane rains on the surface, which carve channels networks. The loss of methane is possibly balanced by outgassing during cryovolcanic event [2]. But hydrocarbons grains deposited onto the surface cannot be recycled. They may be stored in the dunes [3], which were first seen by SAR (Synthetic Aperture Radar) [4]. We focus our study on the mapping of the dune fields in order to determine their global distribution. The aim is to constrain the amount of hydrocarbon material existing in the dunes, and to relate it to the duration of the methane cycle. Data from the Visual and Infrared Mapping Spectrometer (VIMS) and RADAR instruments onboard Cassini spacecraft can be used to map Titan's surface. Infrared images, which are mainly sensitive to composition and grain size, are very complementary to the microwave measurements which depend mainly on roughness and topography. We used spectral criteria after empirical correction of aerosols to map the distribution of heterogeneous units on Titan [5]. These units are compared with SAR images in overlapping regions. Titan's surface mosaics with VIMS VIMS probes the first ten of microns of the ground in seven narrow atmospheric windows in the 0.88 to 5.11 ?m wavelength range. We built infrared mosaics with cubes sorted by spatial resolution, by keeping cubes corresponding to favorable observing conditions (incidence, emergence, phase and time exposure). Band ratios were computed and combined in false color composite images (red as 1.59/1.27-?m, green as 2.03/1.27-?m and blue as 1.27/1.08-?m). Band ratios are useful to minimize the effect of illuminating conditions and albedo variations [6]. Mosaics of Titan's surface were created using images acquired during 42 flybys from Ta (October 26th 2004) to T42 (March 25th 2008). These images have been integrated into a Geographic Information System (GIS). Global maps of band ratios appear fuzzy at high latitudes due to a low spatial resolution and to the presence of haze and clouds. The unfavorable observing geometry, with high incidence angles, induces a very strong scattering by the aerosols in these regions. On the contrary, equatorial and mid-latitudes regions have been covered at a medium resolution, in better observing conditions. In our color composites, most of Titan surface appears either in brown units, bluish units or bright units. We observed that brown units cover 18% of the whole Titan's surface and are found in equatorial regions. Dark blue units cover roughly 2% of Titan's surface. They are systematically associated with bright terrains and are never found isolated within brown units (Fig. 1a). Dune patterns were first observed in the infrared with VIMS during the closest approach at T4 and T20 flybys [7, 8]. The detailed study of dune fields by [8] shows that dune patterns are found mainly in brown units and interdunes can account for the observed spectral variability. Dunes with Radar SAR dataset We also use the RADAR data in SAR mode, mainly sensitive to roughness, surface topography and dielectric constant variations. It is independent of solar light conditions and of the presence of clouds. We retrieved the radar swaths from Ta to T25 (February 22nd 2007) flybys from the PDS website and reprojected the data using the ISIS2 software. The spatial resolution of the SAR images allows the direct imaging of the dunes. Most of Titan's dunes appear longitudinal and resemble terrestrial dunes, such as the ones found in Namibia [4]. Detailed morphologic analysis was performed in [9], who inferred a dominant wind eastward to account for their formation. Two kinds of dunes have been observed: sand seas and small dunes in low sand supply zones. Most of the aeolian sand deposits are found in sand

Le Corre, L.; Le Mouélic, S.; Sotin, C.; Barnes, J. W.; Brown, R. H.; Baines, K.; Buratti, B.; Clark, R.; Nicholson, P.

2008-09-01

137

Modeling Recharge - can it be Done?  

NASA Astrophysics Data System (ADS)

In sub-humid areas where rainfall is relatively low and sporadic, recharge (defined as water movement beyond the active root zone) is the small difference between the much larger numbers rainfall and evapotranspiration. It is very difficult to measure and often modeling is resorted to instead. But is modeling this small number any less difficult than measurement? In Australia there is considerable debate over the magnitude of recharge under different agricultural systems because of its contribution to rising saline groundwater levels following the clearing of native vegetation in the last 100 years. Hence the adequacy of measured and modeled estimates of recharge is under close scrutiny. Results will be presented for the water balance of an intensively monitored 8 year sequence of crops and pastures. Measurements included meteorological inputs, evapotranspiration measured with a pair of weighing lysimeters, and soil water content was measured with TDR and neutron moisture meter. Recharge was estimated from the percolate removed from the lysimeters as well as, when conditions were suitable, from soil water measurements and combined soil water and evapotranspiration measurements. This data was simulated using a comprehensive soil-plant-atmosphere model (APSIM). Comparison with field measurements shows that the recharge can be simulated with an accuracy similar to that with which it can be measured. However, is either sufficiently accurate for the applications for which they are required?

Verburg, K.; Bond, W. J.; Smith, C. J.; Dunin, F. X.

2001-12-01

138

An estimation of the natural value of dune habitats using Empidoidea (Diptera)  

Microsoft Academic Search

The dune landscape along the Belgian coast was evaluated on the basis of its Empidoidea fauna by investigating the faunal composition in different habitat types. The sites selected for sampling were marram dunes, dune grassland, dune slack, scrubby vegetations and three different dune woodlands. White water traps at soil surface level were used to sample five sites from the end

Marc Pollet; Patrick Grootaert

1996-01-01

139

Apparatus for successively charging rechargeable batteries  

SciTech Connect

A charging apparatus charges a plurality of rechargeable batteries individually and in succession. Each of the plurality of rechargeable batteries is coupled to one corresponding charging branch. The charging apparatus comprises a charging completion detecting circuit for detecting a charging completion of a rechargeable battery now in a charging operation, a high voltage detecting circuit for detecting an abnormal voltage of a charging branch now in a charging operation, wherein single pulse is generated responsive to the outputs of the charging completion detecting circuit and the abnormal voltage detecting circuit. A charging branch being connected to the charging voltage source is selectively and automatically switched responsive to the above described single pulse. Furthermore, the charging completion detecting circuit and the abnormal voltage detecting circuit are reset to an initial state responsive to the above described single pulse.

Matsuura, K.; Oyamada, K.

1983-06-07

140

Ecology, management and monitoring of grey dunes in Flanders  

Microsoft Academic Search

Grey dunes are a priority habitat type of the European Union Habitats Directive and demand special attention for conservation\\u000a and management. Knowledge of the ecology of coastal grey dunes can contribute to this policy. Dune grassland succession is\\u000a initiated by fixation and driven by the complex of soil formation (humus accumulation) and vegetation development. Leaching\\u000a and mobilization of CaCO3. which

Sam Provoost; Carole Ampe; Dries Bonte; Eric Cosyns; Maurice Hoffmann

2004-01-01

141

Impacts of vegetation change on groundwater recharge  

NASA Astrophysics Data System (ADS)

Vegetation change is the accepted cause of increasing river salt concentrations and the salinisation of millions of hectares of farm land in Australia. Replacement of perennial native vegetation by annual crops and pastures following European settlement has altered the water balance causing increased groundwater recharge and mobilising the naturally saline groundwater. The Redesigning Agriculture for Australian Landscapes Program, of which the work described here is a part, was established to develop agricultural practices that are more attuned to the delicate water balance described above. Results of field measurements will be presented that contrast the water balance characteristics of native vegetation with those of conventional agricultural plants, and indicate the functional characteristics required of new agricultural practices to reduce recharge. New agricultural practices may comprise different management of current crops and pastures, or may involve introducing totally new species. In either case, long-term testing is required to examine their impact on recharge over a long enough climate record to encompass the natural variability of rainfall that is characteristic of most Australian farming regions. Field experimentation therefore needs to be complemented and extended by computer simulation. This requires a modelling approach that is more robust than conventional crop modelling because (a) it needs to be sensitive enough to predict small changes in the residual recharge term, (b) it needs to be able to simulate a variety of vegetation in different sequences, (c) it needs to be able to simulate continuously for several decades of input data, and (d) it therefore needs to be able to simulate the period between crops, which often has a critical impact on recharge. The APSIM simulation framework will be used to illustrate these issues and to explore the effect of different vegetation combinations on recharge.

Bond, W. J.; Verburg, K.; Smith, C. J.

2003-12-01

142

Computer Program for Predicting Recharge with a Master Recession Curve.  

National Technical Information Service (NTIS)

Water-table fluctuations occur in unconfined aquifers owing to ground-water recharge following precipitation and infiltration, and ground-water discharge to streams between storm events. Ground-water recharge can be estimated from well hydrograph data usi...

C. S. Heppner J. R. Nimmo

2005-01-01

143

30 CFR 56.4203 - Extinguisher recharging or replacement.  

Code of Federal Regulations, 2013 CFR

...STANDARDS-SURFACE METAL AND NONMETAL MINES Fire Prevention and Control Firefighting Equipment § 56.4203 Extinguisher recharging or replacement. Fire extinguishers shall be recharged or replaced with a...

2013-07-01

144

30 CFR 57.4203 - Extinguisher recharging or replacement.  

Code of Federal Regulations, 2013 CFR

...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Fire Prevention and Control Firefighting Equipment § 57.4203 Extinguisher recharging or replacement. Fire extinguishers shall be recharged or replaced with a...

2013-07-01

145

Morphology and dynamics of star dunes from numerical modelling  

NASA Astrophysics Data System (ADS)

Star dunes are giant, pyramid-shaped dunes composed of interlaced arms. These arms are marked by sinuous crests and slip faces of various directions. Their radial symmetry and scale suggest that the star dunes form as a result of complex interactions between a multidirectional wind regime and topography. However, despite their ubiquity in modern sand seas, comparatively little is known about their formation and evolution. Here we present a discrete numerical model of star-dune behaviour based on the feedback mechanisms between wind flow and bedform dynamics. Our simulations indicate that the morphology of star dunes results from the combination of individual longitudinal dunes. We find that the arms of the star dunes propagate only under favourable wind regimes. In contrast to dunes that form from an erodible bed, the crests of the propagating arms are oriented such that sand flux is maximized in the direction of arm growth. Our analysis of the simulated three-dimensional structures suggests that the morphodynamics of the arms are controlled by the frequency of wind reorientation, with a high frequency of reorientation leading to smaller arm dimension and high rates of growth. We suggest that arm propagation is an important process of mass exchange in dune fields.

Zhang, Deguo; Narteau, Clément; Rozier, Olivier; Courrech Du Pont, Sylvain

2012-07-01

146

Dynamics of Barchan dunes in a turbulent boundary layer  

NASA Astrophysics Data System (ADS)

When a fluid flow transports a small amount of solid heavy particles on a non-erodible ground, particles form isolated dunes which slowly propagate downstream. Such dunes have been studied experimentally in a channel. Strikingly, particle heaps always form dunes with crescentic shape, similar to that of Barchan dunes in deserts at a much larger scale. Varying the fluid flow and particle properties, it was found that the dune velocity scales as V ˜1/L where L is the dune length, as expected, but does not follow Bagnold's prediction V ˜u*^3 where u* is the friction velocity; some dependence on the particle Reynolds number, and perhaps relaxation effects in the particle flux on the dune surface, have to be considered. PIV measurements show that the fluid velocity does not increase on the lee side of the dune, as predicted by Hunt and co-workers, but slightly decreases because of the sudden increase of roughness. The roughness change also appears to be of particular importance for understanding the variation of the turbulent stresses -?u'v' along the dune.

Charru, Francois; Franklin, Erick

2008-11-01

147

Quantifying Mountain Front Recharge Using Isotopic Tracers  

NASA Astrophysics Data System (ADS)

To improve our conceptual and quantitative understanding of mountain-front/mountain-block recharge (MFR) associated with the Huachuca Mountains of the Upper San Pedro River Basin in Arizona, we employed a suite of geochemical measurements including isotopic tracers and noble gases. MFR is frequently the dominant source of recharge to alluvial basins in the semiarid Basin and Range province. It consists of mountain runoff that infiltrates at the mountain front (mountain-front recharge), and percolation through the mountain bedrock that reaches the basin via the movement of deep groundwater (mountain-block recharge). The rate of MFR can be estimated from a water balance, a Darcy's law analysis, or inverse modeling of groundwater processes. Despite the large volume of research on water resources in the basin and the critical importance of MFR to the water budget, the best estimates of MFR obtained using these methods may have errors as large as 100%. We find that geochemical tracers address mechanistic questions regarding recharge seasonality, location, and rates as well as addressing groundwater flowpaths and residence times. The gradient of stable isotopes of hydrogen and oxygen in groundwater with elevation mirrors that of regional precipitation, providing a constraint on the location and seasonality of recharge. Stable isotopic signatures indicate that MFR is dominated by winter precipitation but has 1/3 or more contribution from monsoon precipitation. Detectable tritium and 14C values greater than 100 pMC for springs, shallow groundwater in mountain canyons, and from wells along the mountain front indicate decade-scale residence times. Away from the mountain front 14C values rapidly decrease, reaching 12.3±0.2 pMC near the river. This suggests total basin residence times greater than 10,000 years, consistent with past measurements. Ongoing analysis of noble gas concentrations will provide an indication of recharge conditions. The solubility of noble gases in water depends on temperature and pressure; thus, noble gas concentrations provide a means to distinguish water samples recharged at different elevations.

Wahi, A. K.; Ekwurzel, B.; Hogan, J. F.; Eastoe, C. J.; Baillie, M. N.

2005-05-01

148

Global-scale modeling of groundwater recharge  

NASA Astrophysics Data System (ADS)

Long-term average groundwater recharge, which is equivalent to renewable groundwater resources, is the major limiting factor for the sustainable use of groundwater. Compared to surface water resources, groundwater resources are more protected from pollution, and their use is less restricted by seasonal and inter-annual flow variations. To support water management in a globalized world, it is necessary to estimate groundwater recharge at the global scale. Here, we present a best estimate of global-scale long-term average diffuse groundwater recharge (i.e. renewable groundwater resources) that has been calculated by the most recent version of the WaterGAP Global Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time steps). The estimate was obtained using two state-of-the art global data sets of gridded observed precipitation that we corrected for measurement errors, which also allowed to quantify the uncertainty due to these equally uncertain data sets. The standard WGHM groundwater recharge algorithm was modified for semi-arid and arid regions, based on independent estimates of diffuse groundwater recharge, which lead to an unbiased estimation of groundwater recharge in these regions. WGHM was tuned against observed long-term average river discharge at 1235 gauging stations by adjusting, individually for each basin, the partitioning of precipitation into evapotranspiration and total runoff. We estimate that global groundwater recharge was 12 666 km3/yr for the climate normal 1961-1990, i.e. 32% of total renewable water resources. In semi-arid and arid regions, mountainous regions, permafrost regions and in the Asian Monsoon region, groundwater recharge accounts for a lower fraction of total runoff, which makes these regions particularly vulnerable to seasonal and inter-annual precipitation variability and water pollution. Average per-capita renewable groundwater resources of countries vary between 8 m3/(capita yr) for Egypt to more than 1 million m3/(capita yr) for the Falkland Islands, the global average in the year 2000 being 2091 m3/(capita yr). Regarding the uncertainty of estimated groundwater resources due to the two precipitation data sets, deviation from the mean is less than 1% for 50 out of the 165 countries considered, between 1 and 5% for 62, between 5 and 20% for 43 and between 20 and 80% for 10 countries. Deviations at the grid scale can be much larger, ranging between 0 and 186 mm/yr.

Döll, P.; Fiedler, K.

2007-11-01

149

Global-scale modeling of groundwater recharge  

NASA Astrophysics Data System (ADS)

Long-term average groundwater recharge, which is equivalent to renewable groundwater resources, is the major limiting factor for the sustainable use of groundwater. Compared to surface water resources, groundwater resources are more protected from pollution, and their use is less restricted by seasonal and inter-annual flow variations. To support water management in a globalized world, it is necessary to estimate groundwater recharge at the global scale. Here, we present a best estimate of global-scale long-term average diffuse groundwater recharge (i.e. renewable groundwater resources) that has been calculated by the most recent version of the WaterGAP Global Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time steps). The estimate was obtained using two state-of-the-art global data sets of gridded observed precipitation that we corrected for measurement errors, which also allowed to quantify the uncertainty due to these equally uncertain data sets. The standard WGHM groundwater recharge algorithm was modified for semi-arid and arid regions, based on independent estimates of diffuse groundwater recharge, which lead to an unbiased estimation of groundwater recharge in these regions. WGHM was tuned against observed long-term average river discharge at 1235 gauging stations by adjusting, individually for each basin, the partitioning of precipitation into evapotranspiration and total runoff. We estimate that global groundwater recharge was 12 666 km3/yr for the climate normal 1961-1990, i.e. 32% of total renewable water resources. In semi-arid and arid regions, mountainous regions, permafrost regions and in the Asian Monsoon region, groundwater recharge accounts for a lower fraction of total runoff, which makes these regions particularly vulnerable to seasonal and inter-annual precipitation variability and water pollution. Average per-capita renewable groundwater resources of countries vary between 8 m3/(capita yr) for Egypt to more than 1 million m3/(capita yr) for the Falkland Islands, the global average in the year 2000 being 2091 m3/(capita yr). Regarding the uncertainty of estimated groundwater resources due to the two precipitation data sets, deviation from the mean is 1.1% for the global value, and less than 1% for 50 out of the 165 countries considered, between 1 and 5% for 62, between 5 and 20% for 43 and between 20 and 80% for 10 countries. Deviations at the grid scale can be much larger, ranging between 0 and 186 mm/yr.

Döll, P.; Fiedler, K.

2008-05-01

150

Lithium-manganese oxide rechargeable battery  

SciTech Connect

A new type of rechargeable battery in which lithium ions shuttle between a lithium-manganese oxide electrode and a carbon electrode was unveiled recently by chemists from Bell Communications Research (Bellcore), Red Bank, N.J. The new battery--still experimental--is safer, longer lasting, and potentially cheaper to manufacture than other lithium-ion batteries. In addition, it provides three times the energy of nickel-cadmium cells, the most popular type of rechargeable battery. Bellcore scientists believe the new battery could replace nickel-cadmium and small lead-acid batteries in many applications.

Dagani, R.

1993-01-04

151

Rechargeable battery and electrical circuit for charging thereof  

Microsoft Academic Search

This patent describes a nickel-cadmium rechargeable cell for use in an energy-using device having at least one charging terminal contact for recharging the cell. The energy-using device adapted to alternately receive either a standard cylindrical AA, AAA, C or D size non-rechargeable cell has a pair of power terminal contacts spaced apart by a standard distance. The rechargeable cell comprises:

Toops

1987-01-01

152

Control circuit for a solar-powered rechargeable power source and load  

Microsoft Academic Search

A solar rechargeable apparatus is described comprising: a rechargeable power source; a solar panel connected to the rechargeable power source for supplying a charging current to the rechargeable power source; a device connected between the rechargeable power source and the solar panel to prevent discharge of current from the rechargeable power source to the solar panel; a load; and a

R. W. Janda; J. L. Douglas; E. F. Jr. Condon

1993-01-01

153

Fundamental Concepts of Recharge in the Desert Southwest  

Microsoft Academic Search

Recharge in arid basins does not occur in all years or at all locations. To address the temporal and spatial variability of recharge, one must (1) distinguish between recharge and net infiltration, (2) understand travel time in the unsaturated zone, and (3) comprehend the local- and basin-scale deterministic processes and surficial properties that control net infiltration. Net infiltration is the

A. L. Flint; L. E. Flint; J. B. Blainey; J. A. Hevesi

2001-01-01

154

Natural vs. artificial groundwater recharge, quantification through inverse modeling  

NASA Astrophysics Data System (ADS)

Estimating the change in groundwater recharge from an introduced artificial recharge system is important in order to evaluate future water availability. This paper presents an inverse modeling approach to quantify the recharge contribution from both an ephemeral river channel and an introduced artificial recharge system based on floodwater spreading in arid Iran. The study used the MODFLOW-2000 to estimate recharge for both steady- and unsteady-state conditions. The model was calibrated and verified based on the observed hydraulic head in observation wells and model precision, uncertainty, and model sensitivity were analyzed in all modeling steps. The results showed that in a normal year without extreme events, the floodwater spreading system is the main contributor to recharge with 80% and the ephemeral river channel with 20% of total recharge in the studied area. Uncertainty analysis revealed that the river channel recharge estimation represents relatively more uncertainty in comparison to the artificial recharge zones. The model is also less sensitive to the river channel. The results show that by expanding the artificial recharge system, the recharge volume can be increased even for small flood events, while the recharge through the river channel increases only for major flood events.

Hashemi, H.; Berndtsson, R.; Kompani-Zare, M.; Persson, M.

2013-02-01

155

Natural vs. artificial groundwater recharge, quantification through inverse modeling  

NASA Astrophysics Data System (ADS)

Estimating the change in groundwater recharge from an introduced artificial recharge system is important in order to evaluate future water availability. This paper presents an inverse modeling approach to quantify the recharge contribution from both an ephemeral river channel and an introduced artificial recharge system based on floodwater spreading in arid Iran. The study used the MODFLOW-2000 to estimate recharge for both steady and unsteady-state conditions. The model was calibrated and verified based on the observed hydraulic head in observation wells and model precision, uncertainty, and model sensitivity were analyzed in all modeling steps. The results showed that in a normal year without extreme events the floodwater spreading system is the main contributor to recharge with 80% and the ephemeral river channel with 20% of total recharge in the studied area. Uncertainty analysis revealed that the river channel recharge estimation represents relatively more uncertainty in comparison to the artificial recharge zones. The model is also less sensitive to the river channel. The results show that by expanding the artificial recharge system the recharge volume can be increased even for small flood events while the recharge through the river channel increases only for major flood events.

Hashemi, H.; Berndtsson, R.; Kompani-Zare, M.; Persson, M.

2012-08-01

156

Estimating recharge rates with analytic element models and parameter estimation  

USGS Publications Warehouse

Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as calibration targets. The ease and flexibility of AE model construction and evaluation make this approach well suited for recharge estimation. An AE flow model of an undeveloped watershed in northern Wisconsin was optimized to match median annual base flows at four stream gages for 1996 to 2000 to demonstrate the approach. Initial optimizations that assumed a constant distributed recharge rate provided good matches (within 5%) to most of the annual base flow estimates, but discrepancies of >12% at certain gages suggested that a single value of recharge for the entire watershed is inappropriate. Subsequent optimizations that allowed for spatially distributed recharge zones based on the distribution of vegetation types improved the fit and confirmed that vegetation can influence spatial recharge variability in this watershed. Temporally, the annual recharge values varied >2.5-fold between 1996 and 2000 during which there was an observed 1.7-fold difference in annual precipitation, underscoring the influence of nonclimatic factors on interannual recharge variability for regional flow modeling. The final recharge values compared favorably with more labor-intensive field measurements of recharge and results from studies, supporting the utility of using linked AE-parameter estimation codes for recharge estimation. Copyright ?? 2005 The Author(s).

Dripps, W. R.; Hunt, R. J.; Anderson, M. P.

2006-01-01

157

Study on Clogging Mechanism and Control Methods of Artificial Recharge  

Microsoft Academic Search

The severe global fresh water shortage, the over-exploitation of groundwater and its related ecological environment geology problems, the global climate change, all of them are stimulating the study and practice of artificial recharge. But the clogging problem during artificial recharge is always to be the most common obstacle, it can reduce the recharge rate, increase the maintenance cost and shorten

Xueyan Ye; Xinqiang Du; Shengtao Li; Yuesuo Yang

2010-01-01

158

Circuit Model of Battery Recharging by Volume Conduction  

Microsoft Academic Search

Many current implantable devices require large capacity batteries implanted in the body. In this paper we present a new approach of transcutaneous battery recharging by volume conduction and its circuit model. We also analyze the current transmitting efficiency and rechargeable prerequisite of transcutaneous battery recharging by applying this circuit model. The experiments prove the legitimacy of the circuit model.

Zhide Tang; R. J. Sclabassi; Caixin Sun; Jun Zhao; S. A. Hackworth; Mingui Sun

2006-01-01

159

Analysis of the infrastructure for recharging electric vehicles  

Microsoft Academic Search

An analysis of the infrastructure ofr recharging electric vehicles (EV), equivalent to the refueling infrastructure for internal combustion engines (ICE), shows that many of the infrastructure elements required to recharge a large number of EV's in the U.S. are already in place. The U.S. utility industry has sufficient capacity to support at least 13 million EV's if they are recharged

R. Kaiser; C. Graver

1980-01-01

160

Global synthesis of groundwater recharge in semiarid and arid regions  

Microsoft Academic Search

Global synthesis of the findings from ¾140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique

Bridget R. Scanlon; Kelley E. Keese; Alan L. Flint; Lorraine E. Flint; Cheikh B. Gaye; W. Michael Edmunds; Ian Simmers

2006-01-01

161

Global synthesis of groundwater recharge in semiarid and arid regions  

Microsoft Academic Search

Global synthesis of the findings from 140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique

Bridget R. Scanlon; Kelley E. Keese; Alan L. Flint; Lorraine E. Flint; Cheikh B. Gaye; W. Michael Edmunds; Ian Simmers

2006-01-01

162

Potential for Recharge in Agricultural Soils of the Mississippi Delta  

Microsoft Academic Search

Ground water models predict that 5 percent or less of precipitation in the Mississippi Delta region recharges the heavily-used alluvial aquifer; however the presence of agricultural chemicals in ground water suggests more substantial recharge. In a preliminary assessment of the potential for aerial recharge through the agricultural soils of the Bogue Phalia basin in the Mississippi Delta, we applied a

K. S. Perkins; J. R. Nimmo; R. H. Coupe; C. E. Rose; M. A. Manning

2007-01-01

163

Mars Global Digital Dune Database: MC2-MC29  

USGS Publications Warehouse

Introduction The Mars Global Digital Dune Database presents data and describes the methodology used in creating the database. The database provides a comprehensive and quantitative view of the geographic distribution of moderate- to large-size dune fields from 65? N to 65? S latitude and encompasses ~ 550 dune fields. The database will be expanded to cover the entire planet in later versions. Although we have attempted to include all dune fields between 65? N and 65? S, some have likely been excluded for two reasons: 1) incomplete THEMIS IR (daytime) coverage may have caused us to exclude some moderate- to large-size dune fields or 2) resolution of THEMIS IR coverage (100m/pixel) certainly caused us to exclude smaller dune fields. The smallest dune fields in the database are ~ 1 km2 in area. While the moderate to large dune fields are likely to constitute the largest compilation of sediment on the planet, smaller stores of sediment of dunes are likely to be found elsewhere via higher resolution data. Thus, it should be noted that our database excludes all small dune fields and some moderate to large dune fields as well. Therefore the absence of mapped dune fields does not mean that such dune fields do not exist and is not intended to imply a lack of saltating sand in other areas. Where availability and quality of THEMIS visible (VIS) or Mars Orbiter Camera narrow angle (MOC NA) images allowed, we classifed dunes and included dune slipface measurements, which were derived from gross dune morphology and represent the prevailing wind direction at the last time of significant dune modification. For dunes located within craters, the azimuth from crater centroid to dune field centroid was calculated. Output from a general circulation model (GCM) is also included. In addition to polygons locating dune fields, the database includes over 1800 selected Thermal Emission Imaging System (THEMIS) infrared (IR), THEMIS visible (VIS) and Mars Orbiter Camera Narrow Angle (MOC NA) images that were used to build the database. The database is presented in a variety of formats. It is presented as a series of ArcReader projects which can be opened using the free ArcReader software. The latest version of ArcReader can be downloaded at http://www.esri.com/software/arcgis/arcreader/download.html. The database is also presented in ArcMap projects. The ArcMap projects allow fuller use of the data, but require ESRI ArcMap? software. Multiple projects were required to accommodate the large number of images needed. A fuller description of the projects can be found in the Dunes_ReadMe file and the ReadMe_GIS file in the Documentation folder. For users who prefer to create their own projects, the data is available in ESRI shapefile and geodatabase formats, as well as the open Geographic Markup Language (GML) format. A printable map of the dunes and craters in the database is available as a Portable Document Format (PDF) document. The map is also included as a JPEG file. ReadMe files are available in PDF and ASCII (.txt) files. Tables are available in both Excel (.xls) and ASCII formats.

Hayward, Rosalyn K.; Mullins, Kevin F.; Fenton, L. K.; Hare, T. M.; Titus, T. N.; Bourke, M. C.; Colaprete, Anthony; Christensen, P. R.

2007-01-01

164

44 CFR 65.11 - Evaluation of sand dunes in mapping coastal flood hazard areas.  

Code of Federal Regulations, 2010 CFR

...Evaluation of sand dunes in mapping coastal flood hazard areas. (a...consider storm-induced dune erosion potential in its determination of coastal flood hazards and risk mapping...in the evaluation of dune erosion will apply to primary...

2009-10-01

165

44 CFR 65.11 - Evaluation of sand dunes in mapping coastal flood hazard areas.  

Code of Federal Regulations, 2010 CFR

...Evaluation of sand dunes in mapping coastal flood hazard areas. (a...consider storm-induced dune erosion potential in its determination of coastal flood hazards and risk mapping...in the evaluation of dune erosion will apply to primary...

2010-10-01

166

Tour of Park Geology: Sand Dunes  

NSDL National Science Digital Library

This Park Geology site provides links to tours of individual National Parks, Monuments, and Recreation Areas with sand dunes. Where appropriate for each park, links are provided to maps, photographs, geologic research, related links, visitor information, and teacher features (resources for teaching geology with National Park examples). The list includes places such as Death Valley and Mojave National Preserve, along with less well-known areas such as the Pictured Rocks National Lakeshore in Michigan and the Wright Brothers National Memorial in North Carolina.

167

Artificial Groundwater Recharge, San Luis Valley, Colorado.  

National Technical Information Service (NTIS)

Intense use of aquifers for irrigation waters has caused groundwater storage depletion in many areas of the arid and semi-arid west, including the San Luis Valley in south central Colorado. Artificial recharge is a means of alleviating this problem. To sh...

D. K. Sunada J. W. Warner D. J. Molden

1983-01-01

168

REUSE OF MUNICIPAL WASTEWATER FOR GROUNDWATER RECHARGE  

EPA Science Inventory

A survey of groundwater recharge operations with municipal wastewater effluent was conducted. It was found that this activity is being practiced at 10 sites in the U.S. with a total capacity of 77 MGD. The most successful employ percolation with alternate flooding and drying cycl...

169

An approach to identify urban groundwater recharge  

Microsoft Academic Search

Evaluating the proportion in which waters from different origins are mixed in a given water sample is relevant for many hydrogeological problems, such as quantifying total recharge, assessing groundwater pollution risks, or managing water resources. Our work is motivated by urban hydrogeology, where waters with different chemical signature can be identified (losses from water supply and sewage networks, infiltration from

E. Vázquez-Suñé; J. Carrera; I. Tubau; X. Sánchez-Vila; A. Soler

2010-01-01

170

Anode for rechargeable ambient temperature lithium cells  

Microsoft Academic Search

An ambient room temperature, high density, rechargeable lithium battery includes a Li(x)Mg2Si negative anode which intercalates lithium to form a single crystalline phase when x is up to 1.0 and an amorphous phase when x is from 1 to 2.0. The electrode has good reversibility and mechanical strength after cycling.

Chen-Kuo Huang; Subbarao Surampudi; Alan I. Attia; Gerald Halpert

1994-01-01

171

Anode for rechargeable ambient temperature lithium cells  

Microsoft Academic Search

An ambient room temperature, high density, rechargeable lithium battery includes a Li(x)Mg2Si negative anode which intercalates lithium to form a single crystalline phase when x is up to 1.0 and an amorphous phase when x is from 1 to 2.0. The electrode has good reversibility and mechanical strength after cycling.

Chen-Kuo Huang; Subbarao Surampudi; Alan I. Attia; Gerald Halpert

1992-01-01

172

High temperature rechargeable molten salt cell  

Microsoft Academic Search

This patent describes a high temperature rechargeable molten salt cell. It comprises: a member of the group consisting of lithium, lithium aluminum alloy, lithium silicon alloy, sodium, potassium, calcium, magnesium, an alkali metal, a group II A element, a group II A alloy and composite mixtures thereof, as the anode, a chemical compound of the composition XYSâ wherein X is

E. J. Plichta; W. K. Behl

1991-01-01

173

Application potential of rechargeable lithium batteries  

SciTech Connect

Rechargeable lithium cells with Cr /SUB 0.5/ V/sub 0/ /sub 5/S/sub 2/ and MoO/sub 3/ cathodes were investigated in the temperature range of -30/sup 0/C to +25/sup 0/C. The electrolyte was 1.5M LiAsF/sub 6/ in 2-methyl tetrahydrofuran with tetrahydrofuran (50:50 V percent). Current densities and capacities as a function of temperature, cathode utilization efficiencies versus cycle life, and shelf lives were determined. The state of charge could be related to open circuit voltages after partial discharge. The potential of the system for communication applications is discussed. Recent advances in rechargeable lithium batteries were mainly due to the discovery of stable, cyclic ether electrolyte solvents (1) and to the use of rechargeable cathode materials (2). The practical usefulness of rechargeable lithium cells with Cr /SUB 0.5/ V /SUB 0.5/ S/sub 2/ and MoO/sub 3/ cathodes was investigated in the temperature range of -30/sup 0/C to +25/sup 0/C. The electrolyte was mainly 1.5M LiAsF/sub 6/ in 2-methyl tetrahydrofuran with tetrahydrofuran (50:50 V percent). The two cathode materials were chosen because Cr /SUB 0.5/ V /SUB 0.5/ S/sub 2/ resembles TiS/sub 2/ in capacity and cycling behavior and MoO/sub 3/ is a low cost cathode material of interest.

Hunger, H.F.; Bramhall, P.J.

1983-10-01

174

Recharging robot teams: A tanker approach  

Microsoft Academic Search

We examine the use of a tanker robot to distribute energy in a system of autonomous robots. Consider a team of autonomous mobile worker robots performing some task, each with a finite but rechargeable energy supply such as a battery or fuel cell. To work, the robots must expend energy. To expend more energy than is contained in a single

Pawel Zebrowski; Richard T. Vaughan

2005-01-01

175

Battery recharging circuit with indicator means  

Microsoft Academic Search

This patent describes a recharging circuit including a diode and a battery serially connected and coupled in parallel to a power source. The circuit consists of: first means connected across the power source for indicating the presence of a charging current delivered by the power source; second means connected between the power source and the junction of the diode with

Keiper

1986-01-01

176

High reliability lithium rechargeable batteries for specialties  

Microsoft Academic Search

Since their development in the late 1980s, lithium rechargeable batteries have enjoyed rapid growth and wide use as a commodity battery known for its higher energy density storage and lightweight convenience. These same attributes are emerging as a strong platform in power source development for the medical and aerospace sectors with highly customized applications and narrowly defined criteria. Accordingly, this

H. Tsukamoto

2003-01-01

177

All inorganic ambient temperature rechargeable lithium battery  

NASA Astrophysics Data System (ADS)

Having the advantages of high energy density and good charge retention, rechargeable lithium batteries have been of interest to many companies and research organizations within the last 15 years. Various lithium rechargeable systems with different positive electrodes and electrolytes have been reported in literature. Most are using electrolytes with organic solvents. Duracell Inc. has demonstrated the feasibility of using totally inorganic electrolytes based on liquid SO2 for the ambient temperature recharageable lithium battery. The system has lithium as the negative electrode and porous carbon as the positive electrode with SO2 as the depolarizer and electrolyte solvent. A four year cost-shared joint program with the Department of Energy was initiated in October 1980 to investigate the SO2-based electrolytes and to develop an ambient temperature rechargeable lithium battery for future energy storage applications. The ultimate goal of this program is to develop a battery having an energy density over 150 whkg with cycle life of 500 to 800 at 80 to 100 percent depth of discharge. During the four years, SO2 electrolytes with various inorganic salts and various positive electrodes made of porous carbon and solid active materials were evaluated. Promising systems having good rechargeability and high energy density, such as LiCuCl2 and LiLiAlCl4-SO2 carbon were identified. This report summarizes the progress achieved in the program.

Kuo, H. C.; Dey, A. N.; Schlaikjer, C.; Foster, D.; Kallianidis, M.

1987-10-01

178

Recharging Our Sense of Idealism: Concluding Thoughts  

ERIC Educational Resources Information Center

|In this article, the authors aim to recharge one's sense of idealism. They argue that idealism is the Vitamin C that sustains one's commitment to implementing humanistic principles and social justice practices in the work of counselors and educators. The idealism that characterizes counselors and educators who are humanistic and social justice…

D'Andrea, Michael; Dollarhide, Colette T.

2011-01-01

179

Solid polymer electrolytes for rechargeable batteries  

Microsoft Academic Search

SRI International has synthesized novel solid polymer electrolytes for high energy density, rechargeable lithium batteries. We have systematically replaced the oxygens in polyethylene oxide (PEO) with sulfur to reduce the strong hard-acid hard-base interaction, while retaining the favorable helical conformation of the polymer backbone. The best polymer electrolyte produced so far is suitable for a medium power battery. In another

S. C. Narang; D. D. MacDonald

1990-01-01

180

Lithium-polymer electrolyte rechargeable batteries  

Microsoft Academic Search

There have been increasing efforts to develop lithium\\/polymer rechargeable batteries with high rate capability and long cycle life. Research efforts in preparing novel lithium-polymer electrolytes with enhanced conductivity have shown some progress and there is a great need for high conductivity electrolytes. Improvements made in the preparation of electrolytes with enhanced conductivity are described. Results of our research and development

H. V. Venkatasetty

2000-01-01

181

An approach to identify urban groundwater recharge  

NASA Astrophysics Data System (ADS)

Evaluating the proportion in which waters from different origins are mixed in a given water sample is relevant for many hydrogeological problems, such as quantifying total recharge, assessing groundwater pollution risks, or managing water resources. Our work is motivated by urban hydrogeology, where waters with different chemical signature can be identified (losses from water supply and sewage networks, infiltration from surface runoff and other water bodies, lateral aquifers inflows, ...). The relative contribution of different sources to total recharge can be quantified by means of solute mass balances, but application is hindered by the large number of potential origins. Hence, the need to incorporate data from a large number of conservative species, the uncertainty in sources concentrations and measurement errors. We present a methodology to compute mixing ratios and end-members composition, which consists of (i) Identification of potential recharge sources, (ii) Selection of tracers, (iii) Characterization of the hydrochemical composition of potential recharge sources and mixed water samples, and (iv) Computation of mixing ratios and reevaluation of end-members. The analysis performed in a data set from samples of the Barcelona city aquifers suggests that the main contributors to total recharge are the water supply network losses (22%), the sewage network losses (30%), rainfall, concentrated in the non-urbanized areas (17%), from runoff infiltration (20%), and the Besòs River (11%). Regarding species, halogens (chloride, fluoride and bromide), sulfate, total nitrogen, and stable isotopes (18O, 2H, and 34S) behaved quite conservatively. Boron, residual alkalinity, EDTA and Zn did not. Yet, including these species in the computations did not affect significantly the proportion estimations.

Vázquez-Suñé, E.; Carrera, J.; Tubau, I.; Sánchez-Vila, X.; Soler, A.

2010-10-01

182

An approach to identify urban groundwater recharge  

NASA Astrophysics Data System (ADS)

Evaluating the proportion in which waters from different origins are mixed in a given water sample is relevant for many hydrogeological problems, such as quantifying total recharge, assessing groundwater pollution risks, or managing water resources. Our work is motivated by urban hydrogeology, where waters with different chemical signature can be identified (losses from water supply and sewage networks, infiltration from surface runoff and other water bodies, lateral aquifers inflows, ...). The relative contribution of different sources to total recharge can be quantified by means of solute mass balances, but application is hindered by the large number of potential origins. Hence, the need to incorporate data from a large number of conservative species, the uncertainty in sources concentrations and measurement errors. We present a methodology to compute mixing ratios and end-members composition, which consists of (i) Identification of potential recharge sources, (ii) Selection of tracers, (iii) Characterization of the hydrochemical composition of potential recharge sources and mixed water samples, and (iv) Computation of mixing ratios and reevaluation of end-members. The analysis performed in a data set from samples of the Barcelona city aquifers suggests that the main contributors to total recharge are the water supply network losses (22%), the sewage network losses (30%), rainfall, concentrated in the non-urbanized areas (17%), from runoff infiltration (20%), and the Besòs River (11%). Regarding species, halogens (chloride, fluoride and bromide), sulfate, total nitrogen, and stable isotopes (18O2H, and 34S) behaved quite conservatively. Boron, residual alkalinity, EDTA and Zn did not. Yet, including these species in the computations did not affect significantly the proportion estimations.

Vázquez-Suñé, E.; Carrera, J.; Tubau, I.; Sánchez-Vila, X.; Soler, A.

2010-04-01

183

Evidence for community structure and habitat partitioning in coastal dune stiletto flies at the Guadalupe-Nipomo dunes system, California  

PubMed Central

This study provides empirical evidence for habitat selection by North American species of stiletto flies (Diptera: Therevidae), based on local distributions of adults and immatures, and the first hypothesis of community assemblages proposed for a stiletto fly community. Sites at three localities within the Guadalupe-Nipomo dune system were sampled for stiletto flies in 1997 and 2001 by sifting sand, malaise trapping, and hand netting. Nine species were collected from four ecological zones and three intermediate ecological zones: Acrosathe novella (Coquillett), Brachylinga baccata (Loew), Nebritus powelli (Webb and Irwin), Ozodiceromyia sp., Pherocera sp., Tabudamima melanophleba (Loew), Thereva comata Loew, Thereva elizabethae Holston and Irwin, and Thereva fucata Loew. Species associations of adults and larvae with habitats and ecological zones were consistent among sites, suggesting that local distributions of coastal dune stiletto fly species are influenced by differences in habitat selection. In habitats dominated by the arroyo willow,Salix lasiolepsis, stiletto fly larvae of three species were collected in local sympatry, demonstrating that S. lasiolepsis stands along stabilized dune ridges can provide an intermediate ecological zone linking active dune and riparian habitat in the Guadalupe-Nipomo dune system. Sites dominated by European beach grass, Ammophilia arenaria, blue gum, Eucalyptus globulus, and Monterey cypress, Cupressus macrocarpa, are considered unsuitable for stiletto flies, which emphasizes the importance of terrestrial habitats with native vegetation for stiletto fly species. The local distributions of stiletto fly species at the Guadalupe-Nipomo dune system allow the community to be divided into three assemblages; active dune, pioneer scrub, and scrub-riparian. These assemblages may be applicable to other coastal dune stiletto fly communities, and may have particular relevance to stiletto fly species collected in European coastal dunes. The results from this study provide a descriptive framework for studies testing habitat selection in coastal dune stiletto fly species and inform conservation of threatened dune insects.

Holston, Kevin C.

2005-01-01

184

Evidence for community structure and habitat partitioning in coastal dune stiletto flies at the Guadalupe-Nipomo dunes system, California.  

PubMed

This study provides empirical evidence for habitat selection by North American species of stiletto flies (Diptera: Therevidae), based on local distributions of adults and immatures, and the first hypothesis of community assemblages proposed for a stiletto fly community. Sites at three localities within the Guadalupe-Nipomo dune system were sampled for stiletto flies in 1997 and 2001 by sifting sand, malaise trapping, and hand netting. Nine species were collected from four ecological zones and three intermediate ecological zones: Acrosathe novella (Coquillett), Brachylinga baccata (Loew), Nebritus powelli (Webb and Irwin), Ozodiceromyia sp., Pherocera sp., Tabudamima melanophleba (Loew), Thereva comata Loew, Thereva elizabethae Holston and Irwin, and Thereva fucata Loew. Species associations of adults and larvae with habitats and ecological zones were consistent among sites, suggesting that local distributions of coastal dune stiletto fly species are influenced by differences in habitat selection. In habitats dominated by the arroyo willow,Salix lasiolepsis, stiletto fly larvae of three species were collected in local sympatry, demonstrating that S. lasiolepsis stands along stabilized dune ridges can provide an intermediate ecological zone linking active dune and riparian habitat in the Guadalupe-Nipomo dune system. Sites dominated by European beach grass, Ammophilia arenaria, blue gum, Eucalyptus globulus, and Monterey cypress, Cupressus macrocarpa, are considered unsuitable for stiletto flies, which emphasizes the importance of terrestrial habitats with native vegetation for stiletto fly species. The local distributions of stiletto fly species at the Guadalupe-Nipomo dune system allow the community to be divided into three assemblages; active dune, pioneer scrub, and scrub-riparian. These assemblages may be applicable to other coastal dune stiletto fly communities, and may have particular relevance to stiletto fly species collected in European coastal dunes. The results from this study provide a descriptive framework for studies testing habitat selection in coastal dune stiletto fly species and inform conservation of threatened dune insects. PMID:17119624

Holston, Kevin C

2005-12-22

185

Sand dune mobilization caused by regional warming in Otintag, China  

Microsoft Academic Search

Remobilization of fixed or semi-fixed sand dunes is the main process of desertification, which is sensitive to climate change. We analyzed 35-year temperature and precipitation data at three meteorological stations in Otintag Sandy Land, and calculated sand dune mobility index by employing the method suggested by Lancaster. In the last 35 years, the regional temperature tended to increase, whereas precipitation,

Baolin Zhang; Xiaoju Lu; Ruilin Luo

2010-01-01

186

Distribution of Sand Dune Successional Species in Monterey Bay  

Microsoft Academic Search

Malkinson et al. (2003) state that the spatial patterns on sand dunes of individual species changed from clustered to regular as succession progressed as the result of the change in relative importance of facilitation and competition. This theory was used to examine the distribution of sand dune succession species in Monterey Bay. We used a quadrat-based approach on randomly selected

David Priestley; Kate Raine; Charlotte Robinson

187

36 CFR 7.80 - Sleeping Bear Dunes National Lakeshore.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Sleeping Bear Dunes National Lakeshore. 7.80 Section...NATIONAL PARK SYSTEM § 7.80 Sleeping Bear Dunes National Lakeshore. (a) Powerless... (c) Bicycling. (1) The Sleeping Bear Heritage Trail, approximately 27...

2013-07-01

188

Morphologic characteristics and development of falling dunes, northeast Kuwait  

Microsoft Academic Search

Falling dunes are the most common aeolian landform in northeast Kuwait. They are associated with the Jal Az-Zor escarpment. Comparison of aerial photographs from 1972 and 1992 indicates that these dunes developed recently. This change in a relatively short period is attributable mainly to drought, intensive land use and availability of sand source linked to surface disturbance. Military activities during

A. Al-Enezi; K. Pye; R. Misak; S. Al-Hajraf

2008-01-01

189

Spatiotemporal model for the progression of transgressive dunes  

NASA Astrophysics Data System (ADS)

Transgressive dune fields, which are active sand areas surrounded by vegetation, exist on many coasts. In some regions like in Fraser Island in Australia, small dunes shrink while large ones grow, although both experience the same climatic conditions. We propose a general mathematical model for the spatiotemporal dynamics of vegetation cover on sand dunes and focus on the dynamics of transgressive dunes. Among other possibilities, the model predicts growth parallel to the wind with shrinkage perpendicular to the wind, where, depending on geometry and size, a transgressive dune can initially grow although eventually shrink. The larger is the initial area the slower its stabilization process. The model's predictions are supported by field observations from Fraser Island in Australia.

Yizhaq, Hezi; Ashkenazy, Yosef; Levin, Noam; Tsoar, Haim

2013-10-01

190

Sensitivity Analysis of Dune Height Measurements Along Cross-shore Profiles Using a Novel Method for Dune Ridge Extraction  

NASA Astrophysics Data System (ADS)

In barrier islands where communities are subjected to hazards including storm surge and high wave height, coastal dunes offer the first line of defense to property and vital infrastructure. When dunes are over-washed, substantial damage, including complete destruction of buildings and roads can occur. For this reason, dunes are an integral aspect of coastal hazard management. As new, more efficient mapping and analysis technologies evolve, currently used methodologies should be regularly be reexamined in order to ensure the development of the most effective coastal management strategies. Currently, topographical parameters, such as dune height, are usually measured along evenly spaced, shore-perpendicular beach profiles. In previous studies, profile spacing has varied from 20m to over 500m, however, it has been shown that dune height can vary substantially over tens of meters. Profile spacing is a compromise between the resources needed to perform high-resolution measurements and ensuring the capture of meaningful dune features. While it is often clear how the choice of profile spacing will affect the resources needed to perform the analysis, it is often unclear how spacing affects the ability to capture significant dune variation and prevent omission of a narrow dune breach that can open the way for significant flooding. In this study, the structure of alongshore variation in dune height is investigated. The studied dune ridge is located in the Outer Banks, North Carolina, USA and stretches 18km from south of Oregon Inlet (75:31:19W, 35:46:03N) to Rodanthe (75:27:56W, 35:36:31N). The dune ridge is extracted from a 0.5m resolution Digital Elevation Model (DEM) that was interpolated from airborne lidar data using regularized spline with tension. The lidar data was collected in March 2008 by the National Oceanic and Atmospheric Administration. A dune ridge is usually identified as the highest elevation along a shore-perpendicular profile or where ocean-facing slope meets landward-facing slope. In this study, a novel approach for dune ridge extraction is proposed. First, two alongshore end-points of the studied dune ridge are identified using a standard, profile-based method. Then, the dune ridge is traced as the least cost path connecting the two end-points on a cost surface that represents the cumulative penalty for tracing a low elevation path. The cost surface is derived from elevation (i.e., elevation is equal to the cologarithm of the cost). The extracted dune ridge is then sampled at the DEM resolution of 0.5m and analysis of dune ridge height is performed. Statistics on variation in dune height are computed to help understand the sensitivity of dune height measurements to profile spacing and placement. Preliminary results suggest that dune height becomes nearly uncorrelated within 50m and ranges on average nearly a half meter within a five meter window suggesting that dune height measurements are sensitive to profile placement.

Hardin, E.; Mitasova, H.; Overton, M.

2010-12-01

191

Quantifying macropore recharge: Examples from a semi-arid area  

USGS Publications Warehouse

The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically dosed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used us an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in arid and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically closed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used as an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.

Wood, W. W.; Rainwater, K. A.; Thompson, D. B.

1997-01-01

192

Automatic rainfall recharge model induction by evolutionary computational intelligence  

NASA Astrophysics Data System (ADS)

Genetic programming (GP) is used to develop models of rainfall recharge from observations of rainfall recharge and rainfall, calculated potential evapotranspiration (PET) and soil profile available water (PAW) at four sites over a 4 year period in Canterbury, New Zealand. This work demonstrates that the automatic model induction method is a useful development in modeling rainfall recharge. The five best performing models evolved by genetic programming show a highly nonlinear relationship between rainfall recharge and the independent variables. These models are dominated by a positive correlation with rainfall, a negative correlation with the square of PET, and a negative correlation with PAW. The best performing GP models are more reliable than a soil water balance model at predicting rainfall recharge when rainfall recharge is observed in the late spring, summer, and early autumn periods. The "best" GP model provides estimates of cumulative sums of rainfall recharge that are closer than a soil water balance model to observations at all four sites.

Hong, Yoon-Seok Timothy; White, Paul A.; Scott, David M.

2005-08-01

193

Automatic rainfall recharge model induction by evolutionary computational intelligence  

NASA Astrophysics Data System (ADS)

Genetic programming (GP) is used to develop models of rainfall recharge from observations of rainfall recharge and rainfall, calculated potential evapotranspiration (PET) and soil profile available water (PAW) at four sites over a 4 year period in Canterbury, New Zealand. This work demonstrates that the automatic model induction method is a useful development in modeling rainfall recharge. The five best performing models evolved by genetic programming show a highly nonlinear relationship between rainfall recharge and the independent variables. These models are dominated by a positive correlation with rainfall, a negative correlation with the square of PET, and a negative correlation with PAW. The best performing GP models are more reliable than a soil water balance model at predicting rainfall recharge when rainfall recharge is observed in the late spring, summer, and early autumn periods. The ``best'' GP model provides estimates of cumulative sums of rainfall recharge that are closer than a soil water balance model to observations at all four sites.

Hong, Yoon-Seok Timothy; White, Paul A.; Scott, David M.

2005-08-01

194

Where to dig for gold? - Density segregation inside migrating dunes  

NASA Astrophysics Data System (ADS)

If a fluid streams over an extended area of sand, the grains will self-organize by forming complex structures like ripples or dunes. Below the surface, the inner structure of a dune is determined by the individual fate of the particles. In general, agitated granular matter is known to show de-mixing whenever particles differ in size or density, and indeed size segregation is a well-known feature for dunes, called reverse grading. Here we report results of a recent experimental investigation with two particle species differing not in size but in density. Our experimental setup consists of a stadium-shaped flow channel which is filled with water. Measurements are made with a CCD-camera, placed in front of the straight part, recording side views of the dunes migrating downstream. From an initially prepared triangular heap a rapid relaxation to a steady-state solution is observed with constant mass, shape, and velocity. This attractor exhibits all characteristic features of barchan dunes found in nature, namely a gently inclined windward side, crest, brink, and steep lee face. In addition, if the dune consists of a bi-dense mixture of particles, the heavier particles accumulate at the top of migrating dunes whereas light particles are buried at its bottom. This insight into the sedimentology of dunes composed of different types of sand has, loosely speaking, the implication, that in a dune mixed of gold and sand, gold nuggets are likely to be found at the top of the dune, close to the surface at its crest.

Groh, Christopher; Rehberg, Ingo; Kruelle, Christof A.

2013-06-01

195

Manganese oxide cathodes for rechargeable batteries  

NASA Astrophysics Data System (ADS)

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol or hydrogen in various solvents followed by firing at moderate temperatures. The samples have been characterized by wet-chemical analyses, thermal methods, spectroscopic methods, and electron microscopy. It has been found that chemical residues in the oxides such as carboxylates and hydroxyl groups, which could be controlled by varying the reaction medium, reducing agents, and additives, make a significant influence on the electrochemical properties. The Li/Mn ratio in the material has also been found to be a critical factor in determining the rechargeability of the cathodes. The optimized samples exhibit a high capacity of close to 300 mAh/g with good cyclability and charge efficiency. The high capacity with a lower discharge voltage may make these nanostructured oxides particularly attractive for lithium polymer batteries. The research on the manganese oxide cathodes for alkaline batteries is focused on an analysis of the reaction products generated during the charge/discharge processes or by some designed chemical reactions mimicking the electrochemical processes. The factors influencing the formation of Mn3O4 in the two-electron redox process of delta-MnO2 have been studied with linear sweep voltammetry combined with X-ray diffraction. The presence of bismuth, the discharge rate, and the microstructure of the electrodes are found to affect the formation of Mn3O4, which is known to be electrochemically inactive. A faster voltage sweep and a more intimate mixing of the manganese oxide and carbon in the cathode are found to suppress the formation of Mn3O4. Bismuth has also been found to be beneficial in the one-electron process of gamma-MnO 2 when incorporated into the cathode. The results of a series of chemical reactions reveal that bismuth is blocking some reaction paths leading to the unwanted birnessite or Mn3O4. Barium is also found to play a similar role, but it is less effective than bismuth for the same amount of additive. Optimization of the additives has the potential to make the rechargeable alkaline cells based on manganese oxides to successfully compete with other rechargeable systems due to their low cost, environmental friendliness, and excellent safety features.

Im, Dongmin

196

Feasibility of using sand dunes as archives of old air  

NASA Astrophysics Data System (ADS)

Large unaltered samples of the atmosphere covering the past century would complement the history of atmospheric gases obtained from bubbles in ice cores, enabling measurement of geochemically important species such as O2, 14CH4, and 14CO. Sand dunes are a porous media with interstitial air in diffusive contact with the atmosphere, somewhat analogous to the unconsolidated layer of firn atop glaciers. Recent studies have demonstrated the value of firn as an archive of old air [Battle et al., 1996; Bender et al., 1994a]. Unlike firn, sand dunes are incompressible and so remain permeable to greater depths and may extend the firn record into the past century. To evaluate the feasibility of using sand dunes as archives of old air, we drilled 60 m deep test holes in the Algodones Dunes, Imperial Valley, California. The main objective was to see if the air in a sand dune is as old as predicted by a diffusion model, or if the dune is rapidly flushed by advective pumping during windstorms and barometric pressure changes. We dated the air with chlorofluorocarbons and krypton-85, anthropogenic tracers whose atmospheric concentrations are known and have been increasing rapidly in the past half century. These tracer data match the pure diffusion model well, showing that advection in this dune is negligible compared to diffusion as a transport mechanism and that the mean age of the air at 61 m depth is ˜10 years. Dunes therefore do contain old air. However, dunes appear to suffer from two serious drawbacks as archives. Microbial metabolism is evident in elevated CO2 and N2O and depressed CH4 and O2 concentrations in this dune, corrupting the signals of interest in this and probably most dunes. Second, isotopic analyses of N2 and O2 from the dune show that fractionation of the gases occurs due to diffusion of water vapor, complicating the interpretation of the O2 signal beyond the point of viability for an air archive. Sand dunes may be useful for relatively inert gases with large atmospheric concentration changes such as chlorofluorocarbons.

Severinghaus, Jeffrey P.; Keeling, Ralph F.; Miller, Benjamin R.; Weiss, Ray F.; Deck, Bruce; Broecker, Wallace S.

1997-07-01

197

Late Pleistocene dune activity in the central Great Plains, USA  

NASA Astrophysics Data System (ADS)

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of cold, short growing seasons with relatively low precipitation and low atmospheric CO2 that increased plant moisture stress, limiting the ability of vegetation to stabilize active dune sand. The apparent coexistence of large mobile dunes with boreal forest taxa suggests a Late Pleistocene environment with few modern analogs.

Mason, J. A.; Swinehart, J. B.; Hanson, P. R.; Loope, D. B.; Goble, R. J.; Miao, X.; Schmeisser, R. L.

2011-12-01

198

Dune migration and slip face advancement in the Rabe Crater dune field, Mars  

NASA Astrophysics Data System (ADS)

Eight overlapping images of a dune slip face in Rabe Crater (35°E, 44°S) from the Mars Global Surveyor Mars Orbiter Camera show changes interpreted to be multiple grainflow events that would indicate present-day sand saltation and dune migration. New occurrences of these features appear sporadically throughout late southern summer and early fall, and then no further changes occur throughout winter. By the following summer the pattern of old streaks had been almost completely covered by new dark streaks. Assuming that this activity is typical from year to year, migration rates are estimated to be on the order of 1-2 cm per martian year, produced by south to southeasterly winds that blow mostly during the southern spring and early summer. This slow migration rate is consistent with a present-day sediment state that is either transport or availability limited.

Fenton, Lori K.

2006-10-01

199

The Role of Algal Mats on Community Succession in Dunes and Dune Slacks  

Microsoft Academic Search

Different kinds of algal communities can live in dune slacks that may become temporarily flooded or remain moist throughout\\u000a the year due to fluctuations in the proximity of the water table (Brown and McLachlan 1990). This chapter focuses on changes\\u000a in the composition of algal communities during periods of flooding and drought, with special emphasis on the hydrological\\u000a characteristics of

G. Vázquez

200

Rechargeable Infection-responsive Antifungal Denture Materials  

PubMed Central

Candida-associated denture stomatitis (CADS) is a significant clinical concern. We developed rechargeable infection-responsive antifungal denture materials for potentially managing the disease. Polymethacrylic acid (PMAA) was covalently bound onto diurethane dimethacrylate denture resins in the curing step. The PMAA resins bound cationic antifungal drugs such as miconazole and chlorhexidine digluconate (CG) through ionic interactions. The anticandidal activities of the drug-containing PMAA-resin discs were sustained for a prolonged period of time (weeks and months). Drug release was much faster at acidic conditions (pH 5) than at pH 7. Drugs bound to the denture materials could be “washed out” by treatment with EDTA, and the drug-depleted resins could be recharged with the same or a different class of anticandidal drugs. These results suggest clinical potential of the newly developed antifungal denture materials in the management of CADS and other infectious conditions.

Cao, Z.; Sun, X.; Yeh, C.-K.; Sun, Y.

2010-01-01

201

Solid polymer electrolytes for rechargeable batteries  

SciTech Connect

SRI International has synthesized novel solid polymer electrolytes for high energy density, rechargeable lithium batteries. We have systematically replaced the oxygens in PEO with sulfur to reduce the strong hard-acid hard-base interaction, while retaining the favorable helical conformation of the polymer backbone. The best polymer electrolyte produced so far is suitable for a medium power battery. In another effort, we have synthesized single ion conducting polymer electrolytes based on polyethyleneimine, polyphosphazene, and polysiloxane backbones. The single ion conducting polymer electrolytes will allow greater depth of charge and discharge by preventing dc polarization. The best conductivity so far with single ion conductors is 1.0 {times} 10{sup {minus}3} Scm{sup {minus}1} at room temperature. Further optimization of electrical and mechanical properties will allow the use of these polymer electrolytes in the fabrication of rechargeable lithium batteries. 8 tabs.

Narang, S.C.; Macdonald, D.D.

1990-11-01

202

Great Sand Dunes National Monument and Preserve  

NSDL National Science Digital Library

This National Park Service website describes the natural resources of this park such as plants, mammals and birds (with species lists); endemic or rare species; geology; hydrology; and wind (eolian) systems. These natural resources include a high mountain valley holding the tallest dunes in North America and flanked by some of the highest peaks in the Rocky Mountains; unique wind-powered geologic systems; insects physically adapted to life in the sand and found nowhere else; alpine lakes and tundra; disappearing ponds; and interdunal wetlands. There is information on hiking and camping in the park and planning a visit; cultural history of the park area including that of ancient Americans; and a photo gallery.

203

Vegetation controls on the maximum size of coastal dunes.  

PubMed

Coastal dunes, in particular foredunes, support a resilient ecosystem and reduce coastal vulnerability to storms. In contrast to dry desert dunes, coastal dunes arise from interactions between biological and physical processes. Ecologists have traditionally addressed coastal ecosystems by assuming that they adapt to preexisting dune topography, whereas geomorphologists have studied the properties of foredunes primarily in connection to physical, not biological, factors. Here, we study foredune development using an ecomorphodynamic model that resolves the coevolution of topography and vegetation in response to both physical and ecological factors. We find that foredune growth is eventually limited by a negative feedback between wind flow and topography. As a consequence, steady-state foredunes are scale invariant, which allows us to derive scaling relations for maximum foredune height and formation time. These relations suggest that plant zonation (in particular for strand "dune-building" species) is the primary factor controlling the maximum size of foredunes and therefore the amount of sand stored in a coastal dune system. We also find that aeolian sand supply to the dunes determines the timescale of foredune formation. These results offer a potential explanation for the empirical relation between beach type and foredune size, in which large (small) foredunes are found on dissipative (reflective) beaches. Higher waves associated with dissipative beaches increase the disturbance of strand species, which shifts foredune formation landward and thus leads to larger foredunes. In this scenario, plants play a much more active role in modifying their habitat and altering coastal vulnerability than previously thought. PMID:24101481

Durán, Orencio; Moore, Laura J

2013-10-07

204

Effects of sand fences on coastal dune vegetation distribution  

NASA Astrophysics Data System (ADS)

Sand fences are important human adjustments modifying the morphology of developed shores. The effects of sand fences on sediment transport and deposition in their initial stages have been well studied, but little is known about the effect of deteriorated sand fences that have become partially buried low scale barriers within the dune, potentially benefiting vegetation growth by protecting it from onshore stress. Data on vegetation, topography and fence characteristics were gathered at three dune sites in Ocean City, New Jersey on September 2007 and March 2008 to evaluate the effect of fences within the dune on vegetation distribution. Variables include: distance landward of dune toe, degree of sheltering from onshore stressors, net change in surface elevation (deposition or erosion), vegetation diversity and density, presence of remnant fence, and distance landward of fence. Results for the studied environment reveal that 1) vegetation diversity or density does not increase near remnant fences because most remnants are lower than average vegetation height and can not provide shelter; but 2) vegetation distribution is related to topographic variables, such as degree of sheltering, that are most likely the result of sand accretion caused by fence deployment. Fence deployment that prioritizes the creation of topographically diverse dunes within a restricted space may increase the diversity and density of the vegetation, and the resilience and value of developed dunes. Managers should consider the benefits of using sand fences on appropriately wide beaches to create a protective dune that is also diverse, functional and better able to adapt to change.

Grafals-Soto, Rosana

2012-04-01

205

Rechargeable Infection-responsive Antifungal Denture Materials  

Microsoft Academic Search

Candida-associated denture stomatitis (CADS) is a significant clinical concern. We developed rechargeable infection-responsive antifungal denture materials for potentially managing the disease. Polymethacrylic acid (PMAA) was covalently bound onto diurethane dimethacrylate denture resins in the curing step. The PMAA resins bound cationic antifungal drugs such as miconazole and chlorhexidine digluconate (CG) through ionic interactions. The anticandidal activities of the drug-containing PMAA-resin

Z. Cao; X. Sun; C.-K. Yeh; Y. Sun

2010-01-01

206

Rechargeable Antibacterial and Antifungal Polymeric Silver Sulfadiazines  

Microsoft Academic Search

Poly(methyl methacrylate) (PMMA)-based rechargeable antibacterial and antifungal polymeric silver sulfadiazines were prepared by copolymerizing acryloyl sulfadiazine with methyl methacrylate and sequentially treating the copolymers with dilute silver nitrate aqueous solutions. The chemical structures of the samples were characterized by FT-IR, 1H-NMR, XPS, and TGA analyses. On contact, the PMMA-based polymeric silver sulfadiazines provided 100% inactivation of 108—109 CFU\\/mL of Escherichia

Zhengbing Cao; Xinbo Sun; Yuyu Sun; Hao Fong

2009-01-01

207

Rechargeable Lithium Batteries with Aqueous Electrolytes  

NASA Astrophysics Data System (ADS)

Rechargeable lithium-ion batteries that use an aqueous electrolyte have been developed. Cells with LiMn_2O_4 and VO_2(B) as electrodes and 5 M LiNO_3 in water as the electrolyte provide a fundamentally safe and cost-effective technology that can compete with nickel-cadmium and lead-acid batteries on the basis of stored energy per unit of weight.

Li, Wu; Dahn, J. R.; Wainwright, D. S.

1994-05-01

208

Recharge pattern of contemporary glass ionomer restoratives  

PubMed Central

Background: As glass ionomers have the ability to reload fluoride from outside sources, the aim was to compare the recharge pattern of six glass ionomer cements after exposure to fluoride. Materials and Methods: Fuji VII, Fuji IX, Riva Pink, Riva Bleach, Ketac Fil and Fuji IX Extra were investigated. The fluoride-containing materials used were tooth paste and mouth wash (Colgate). Specimens of each material (n=15) were immersed separately in deionized water for 59 days. Then the samples of each material were divided into three groups of five each. Two groups were recharged for 2, 20 and 60 min daily during three consecutive weekly intervals and then no treatment for one week. The third group was used as control. Fluoride release measurements (?g/cm2/day) were made in every 24 h. One-way and repeated measures analysis of variance tests were used. Results: Tooth paste recharged materials showed higher level of recharge. On day 1, the difference of fluoride release from different treatment groups of different materials except for Fuji IX Extra were not significant (P>0.05). On days 7 and 14, the differences observed were significant (P<0.05) for all materials except for Fuji VII (tooth paste versus mouth wash) and Trial Fuji IX (mouth wash versus control) and on day 14 for Rvia Pink (mouth wash versus control). On days 21 and 28, the differences observed were significant for all the materials (P<0.05) except for Riva Pink (toothpaste versus mouth wash), Riva Bleach, Ketac Fil and Trial FujiI X (mouth wash versus control) on day 28. Conclusion: A time tabled schedule of application of fluoride-containing materials could help to achieve high fluoride release.

Arbabzadeh-Zavareh, Farahnaz; Gibbs, Tim; Meyers, Ian A.; Bouzari, Majid; Mortazavi, Shiva; Walsh, Laurence J.

2012-01-01

209

Application potential of rechargeable lithium batteries  

Microsoft Academic Search

Rechargeable lithium cells with Cr \\/SUB 0.5\\/ Vâ âSâ and MoOâ cathodes were investigated in the temperature range of -30°C to +25°C. The electrolyte was 1.5M LiAsFâ in 2-methyl tetrahydrofuran with tetrahydrofuran (50:50 V percent). Current densities and capacities as a function of temperature, cathode utilization efficiencies versus cycle life, and shelf lives were determined. The state of charge could

H. F. Hunger; P. J. Bramhall

1983-01-01

210

Recharge monitoring in an interplaya setting  

SciTech Connect

The objective of this investigation is to monitor infiltration in response to precipitation events in an interplaya setting. The authors evaluated data gathered from the interplaya recharge monitoring installation at the Pantex Plant from March through December 1998. They monitored thermocouple psychrometer (TCP) instruments to measure water potential and time-domain reflectometry (TDR) probes to measure water content and bulk soil conductivity. Heat-dissipation sensor (HDS) instruments were monitored to supplement the TCP data.

Scanlon, B.R.; Reedy, R.C.; Liang, J. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology

1999-03-01

211

Lithium-manganese oxide rechargeable battery  

Microsoft Academic Search

A new type of rechargeable battery in which lithium ions shuttle between a lithium-manganese oxide electrode and a carbon electrode was unveiled recently by chemists from Bell Communications Research (Bellcore), Red Bank, N.J. The new battery--still experimental--is safer, longer lasting, and potentially cheaper to manufacture than other lithium-ion batteries. In addition, it provides three times the energy of nickel-cadmium cells,

Dagani

1993-01-01

212

High specific power lithium polymer rechargeable battery  

Microsoft Academic Search

PolyPlus Battery Company (PPBC) is developing an advanced lithium polymer rechargeable battery based on its proprietary positive electrode. This battery offers high steady-state (>250 W\\/kg) and peak power densities (3000 W\\/kg), in a low cost and environmentally benign format. This PolyPlus lithium polymer battery also delivers high specific energy. The first generation battery has a energy density of 100 Wh\\/kg

May-Ying Chu; Lutgard De Jonghe; Steven Visco

1996-01-01

213

Solid polymer electrolytes for rechargeable batteries  

Microsoft Academic Search

SRI International has synthesized and tested new, dimensionally stable polymer electrolytes for high energy density rechargeable lithium batteries. We have prepared semi-interpenetrating networks of sulfur-substituted polyethyleneoxide with tetraethylorthosilicate (TEOS). The in situ hydrolysis of TEOS produces a mechanically stable three-dimensional network that entangles the polymer electrolytes and makes the film dimensionally flexible and stable. With this approach, the best dimensionally

Subhash C. Narang; Susanna C. Ventura

1992-01-01

214

Rechargeable batteries and battery management systems design  

Microsoft Academic Search

Estimated worldwide sales for rechargeable batteries, was around US$36 billion in 2008 and this is expected to grow towards US$51 billion by 2013. As per market reports, US demand for primary and secondary batteries will increase by 2.5% annually to 16.8 billion in 2012, while primary batteries will account for 5.8 billion with a growth rate of 3%. The insatiable

N. Kularatna

2010-01-01

215

Rechargeable lithium batteries with aqueous electrolytes.  

PubMed

Rechargeable lithium-ion batteries that use an aqueous electrolyte have been developed. Cells with LiMn(2)O(4) and VO(2)(B) as electrodes and 5 M LiNO(3) in water as the electrolyte provide a fundamentally safe and cost-effective technology that can compete with nickelcadmium and lead-acid batteries on the basis of stored energy per unit of weight. PMID:17744893

Li, W; Dahn, J R; Wainwright, D S

1994-05-20

216

Sand dunes on the central Delmarva Peninsula, Maryland and Delaware  

USGS Publications Warehouse

Inconspicuous ancient sand dunes are present in parts of the central Delmarva Peninsula, Maryland and Delaware. Many dunes are roughly V-shaped, built by northwest winds, especially on the east sides of some of the large rivers. On the uplands, the form and spacing of the dunes are variable. A surficial blanket composed mainly of medium and fine-grained sand-the Parsonsburg Sand-forms both the ancient dunes and the broad plains between the dunes. The sand that forms the dunes is massive and intensely burrowed in the upper part; traces of horizontal or slightly inclined bedding appear near the base. Quartz is the dominant mineral constituent of the sand. Microline is abundant in the very fine to fine sand fraction. The heavy-mineral assemblages (high zircon, tourmaline, rutile) are more mature than in most of the possible source rocks. The most abundant minerals in the clay-sized fraction are dioctahedral vermiculite, kaolinite, illite, montmorillonite, and gibbsite. The first four minerals are common in deposits of late Wisconsin and Holocene age. The gibbsite may be detrital, coming from weathered rocks of Tertiary age. The soil profile in the dune sand is weakly to moderately developed. At or near the base of the Parsonsburg Sand are peaty beds that range in age from about 30,000 to about 13,000 radiocarbon years B.P. Microfloral assemblages in the peaty beds suggest that the dunes on the uplands formed in a spruce parkland during the late Wisconsin glacial maximum. The river dunes may also be of late Wisconsin age, but could be Holocene.

Denny, Charles Storrow; Owens, James Patrick

1979-01-01

217

Ground water recharge from Lake Chad  

SciTech Connect

Lake Chad is a shallow, closed basin lake located in Sub-Sharan Africa. It has the largest drainage basin of any lake in the world, and is also very old, being formed by tectonic processes during the Cretaceous. These features should combine to form a saline lake, but the open waters of Lake Chad are reasonably fresh, having a total dissolved solids concentration of about 320 mg/1. This apparent discrepancy can be explained by noting that recharge of the unconfined aquifer to the SW in Nigeria by ground water infiltration through the lakebed can remove significant quantities of water and dissolved solutes from the lake. The authors have measured and calculated ground water infiltration and velocities by several techniques. Direct, volumetric measurements of ground water recharge seepage give velocities on the order of .28-8.8 x 10/sup -3/ m/day. Tracer monitoring in a borehole dilution test yielded ground water velocities of 3.6 m/day to the SW (away from the lake). Hydraulic conductivities approx. .004-.6 m/day were determined by falling head measurements. Finally, using static water levels, the potentiometric surface within approx. 80 km of the southwest portion of Lake Chad yields water table gradients of 1.0-1.7 x 10/sup -4/ away from the lake. These results confirm that surface water and solute inflow to Lake Chad is removed by recharge to the unconfined aquifer in Nigeria.

Isiorho, S.; Matisoff, G.; McCall, P.L.

1985-01-01

218

Profile measurement and simulation of a transverse dune field in the Lençóis Maranhenses  

Microsoft Academic Search

In this work, we report measurements of the height profile of transverse dunes in the coastal dune field known as “Lençóis Maranhenses”, northeastern Brazil. Our measurements show that transverse dunes with approximately the same height present a variable brink position relative to the crest, in contrast to the case of barchan dunes. Based on our field data, we present a

E. J. R. Parteli; V. Schwämmle; H. J. Herrmann; L. H. U. Monteiro; L. P. Maia

2006-01-01

219

Absolute dune ages and implications for the time of formation of gullies in Nirgal Vallis, Mars  

Microsoft Academic Search

Transverse dunes cover the valley floor of Nirgal Vallis, a 670 km long valley network at 318°E and 29°S. The dunes are superposed by small undeformed impact craters, which implies that the dunes are inactive under present atmospheric conditions. The last active phase of dune movement (absolute age) can be determined by crater size frequency distributions. The derived absolute ages

D. Reiss; S. van Gasselt; G. Neukum; R. Jaumann

2004-01-01

220

Probabilistic analysis of the effects of climate change on groundwater recharge  

Microsoft Academic Search

Groundwater recharge is likely to be affected by climate change. In semiarid regions where groundwater resources are often critical, annual recharge rates are typically small and most recharge occurs episodically. Such episodic recharge is uncertain and difficult to predict. This paper analyzes the impacts of different climate predictions on diffuse episodic recharge at a low-relief semiarid rain-fed agricultural area. The

Gene-Hua Crystal Ng; Dennis McLaughlin; Dara Entekhabi; Bridget R. Scanlon

2010-01-01

221

Modelling overbank flood recharge at a continental scale  

NASA Astrophysics Data System (ADS)

Accounting for groundwater recharge from overbank flooding is required to reduce uncertainty and error in river loss terms and groundwater sustainable yield calculations. However, continental and global scale models of surface water-groundwater interactions rarely include an explicit process to account for overbank flood recharge (OFR). This paper upscales previously derived analytical equations to a continental scale using national soil atlas data and satellite imagery of flood inundation, resulting in recharge maps for seven hydrologically distinct Australian catchments. Recharge for three of the catchments was validated against independent recharge estimates from bore hydrograph responses and one catchment was additionally validated against point scale recharge modelling and catchment scale change in groundwater storage. Flood recharge was predicted for four of the seven catchments modelled, but there was also unexplained recharge present from the satellite flood inundation mapping data. At a catchment scale, recharge from overbank flooding was somewhat under predicted using the analytical equations, but there was good confidence in the spatial patterns of flood recharge produced. Due to the scale of the input data, there were no significant relationships found when compared at a point scale. Satellite derived flood inundation data and uncertainty in soil maps were the key limitations to the accuracy of the modelled recharge. Use of this method to model OFR was found to be appropriate at a catchment to continental scale, given appropriate data sources. The proportion of OFR was found to be at least 4% of total change in groundwater storage in one of the catchments for the period modelled, and at least 15% of the riparian recharge. Accounting for OFR is an important, and often overlooked, requirement for closing water balances in both the surface water and groundwater domains.

Doble, R.; Crosbie, R.; Peeters, L.; Joehnk, K.; Ticehurst, C.

2013-10-01

222

Control of Sand Movement on Model Dune by Fence Installation  

NASA Astrophysics Data System (ADS)

Recent desertification has been one of serious environmental issues. It is important to elucidate mechanisms of the sand movement from sand dunes with considering the relations between the dune shape and the turbulent air flow. This relation can be applied to predict and prevent the desertification. In this study, the shape of the dune surface and the erosion rate are measured by the method of laser-sheet visualization. Laser-doppler velocimetry (LDV) has been used for turbulence measurement. Effects of an installed fence on the erosion rate are discussed with emphasis on influences of its position and height. The erosion has been either suppressed or enhanced by the fence. Since there exist two strong erosion areas due to the backflow and wake induced by the fence. In the present experimental conditions, the top of the dune is the most suitable position of the fence for preventing erosion.

Sakamoto, Yusuke; Shimazu, Shota; Tsukahara, Takahiro; Yamamoto, Makoto; Kawaguchi, Yasuo

2010-03-01

223

Sand Furrows: A new surface feature on martian dunes  

NASA Astrophysics Data System (ADS)

Planetary geomorphology is at the forefront of today's Geoscience endeavours. A characteristic of frontier science is the discovery of new landforms and processes. Sand furrows are a new geomorphic feature that has not been previously described. They are ubiquitous and occur on 95% of polar dune images. Furrows are shallow and narrow erosion forms which can extend up to 300 m along a dune surface. Patterns are reminiscent of fluid flow, perhaps even fluvial flow (e.g., sinuosity, braiding and anastomosing) and are often slope-normal. However, furrows also display attributes that defy gravity (e.g., upslope trending flow paths) and they are not associated with terminal deposits. This suggests that the formative fluid is likely to be a pressurised gas. Cryo-venting has been proposed to explain the formation of dark spots and fans in the seasonal ice cap. It has also been linked to the formation of araniform. Here it is proposed to be the process by which aeolian sediment is eroded to form sand furrows. During the Martian spring, basal sublimation of the seasonal CO2 ice cap occurs on dune surfaces. Weaknesses in the ice allow pressurised gas and some dune sediment to be transported through vents to the surface. Furrows are eroded along the gas flow paths as it moves towards the vent. Cryo-venting is therefore identified as a new style of sediment transport on aeolian dunes in our solar system, and one that is, so far, unique to Mars. An estimate of the sand volume eroded from a sample dune during one Mars' spring is geomorphologically significant and is equivalent to that of a small dome dune on Mars (500m^3). The deposits are diffuse and extend into the interdune as well as back onto the source dune. The geomorphic efficacy of cryo-venting as a mechanism of aeolian dune erosion is dependent on the magnitude and frequency of venting, the location of vents and the scale of the source dune. Small dunes may undergo accelerated erosion rates as the ability to intersect vented sediment is reduced by a small surface area.

Bourke, Mary

2013-04-01

224

Recruitment limitation of native species in invaded coastal dune communities  

Microsoft Academic Search

Recruitment limitation may limit the ability of sites to regenerate after disturbances such as weed invasion and weed management.\\u000a We investigated seed bank constraints and dispersal limitation in coastal dune communities on the east coast of Australia.\\u000a The ability of sites to regenerate naturally following weed removal was assessed in coastal dune communities invaded by the\\u000a invasive alien, bitou bush

Kris French; Tanya J. Mason; Natalie Sullivan

2011-01-01

225

Rip currents, mega-cusps, and eroding dunes  

USGS Publications Warehouse

Dune erosion is shown to occur at the embayment of beach mega-cusps O(200??m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18??km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40??m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence of waves owing to refraction over the Monterey Bay submarine canyon results in larger wave heights. The large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale. The strongly refracted waves and narrow bay aperture result in near normal wave incidence, resulting in well-developed, persistent rip currents along the entire shoreline. The alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95% confidence. The alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95% confidence. Therefore, it is concluded the mega-cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega-cusp. ?? 2007 Elsevier B.V. All rights reserved.

Thornton, E. B.; MacMahan, J.; Sallenger, Jr. , A. H.

2007-01-01

226

On the transition between 2D and 3D dunes  

Microsoft Academic Search

Sediment transport in sand-bedded alluvial channels is strongly conditioned by bedforms, the planimetric morphology of which can be either two- or three- dimensional. Experiments were undertaken to examine the processes that transform the bed configuration from two-dimensional (2D) dunes to three- dimensional (3D) dunes. A narrowly graded, 500 lm size sand was subjected to a 0Æ15 m deep, non-varying mean

JEREMY G. VENDITTI; MICHAEL CHURCH; SEAN J. BENNETT

2005-01-01

227

Computer simulation of the dynamics of a dune system  

Microsoft Academic Search

The mobile dune system of the Doñana National Park (southwest Spain) covers an area of 100 km2. It is formed by several transverse dune fronts 5–20 m high, lying parallel to the beach, and separated by flat slacks covered by scrub vegetation. Duns move from the beach inland at a rate of 2.5 m per year, burying the slack vegetation

Francisco de Castro

1995-01-01

228

Pathomimie de l'enfant: ? propos d'une observation  

PubMed Central

La pathomimie cutanée se définit comme une maladie factice, provoquée dans un etat de conscience claire par le patient lui-même, au niveau du revêtement cutanéo-muqueux et/ou des phanères. Rare chez l'enfant, il s'agit d'une manifestation psychopathologique potentiellement grave et souvent difficile à prendre en charge. Nous rapportons le cas d'une fillette de 10 ans présentant une pathomimie sous forme de lésions excoriées multiples du visage.

Abilkassem, Rachid; Dini, Nezha; Ourai, Hakim; Kmari, Mohamed; Agadr, Aomar

2013-01-01

229

Soil pH and species diversity in coastal dunes  

Microsoft Academic Search

Soil pH was measured at two different spatial scales in coastal dunes on Norderney, North Sea, and in Mecklenburg-Vorpommern, Baltic Sea, Germany. Relationships between the variability in soil pH, species richness and species diversity are presented. Species richness and diversity were highest in grey dunes, where soil pH was at intermediate levels; both variables were lower in yellow and brown

M. Isermann

2005-01-01

230

Barchan dune corridors: Field characterization and investigation of control parameters  

NASA Astrophysics Data System (ADS)

The structure of the barchan field located between Tarfaya and Laayoune (Atlantic Sahara, Morocco) is quantitatively investigated and compared to that in La Pampa de la Joya (Arequipa, Peru). On the basis of field measurements, we show how the volume, the velocity, and the output sand flux of a dune can be computed from the value of its body and horn widths. The dune size distribution is obtained from the analysis of aerial photographs. It shows that these fields are in a statistically homogeneous state along the wind direction and present a "corridor" structure in the transverse direction, in which the dunes have a rather well selected size. Investigating the possible external parameters controlling these corridors, we demonstrate that none among topography, granulometry, wind, and sand flux is relevant. We finally discuss the dynamical processes at work in these fields (collisions and wind fluctuations) and investigate the way they could regulate the size of the dunes. Furthermore, we show that the overall sand flux transported by a dune field is smaller than the maximum transport that could be reached in the absence of dunes, i.e., in saltation over the solid ground.

Elbelrhiti, H.; Andreotti, B.; Claudin, P.

2008-06-01

231

Effects of topography on the dune forming winds on Titan  

NASA Astrophysics Data System (ADS)

Cassini observed hundreds of dune fields on Titan, nearly all of which lie in the tropics and suggest westerly (from west to east) winds dominate at the surface. Most GCMs however have obtained easterly surface winds in the tropics, seemingly contradicting the wind direction suggested by the dunes. This has led to an active debate in the community about the origin of the dune forming winds on Titan and their direction and modality. This discussion is mostly driven by a study of Earth dunes seen as analogous to Titan. One can find examples of dunes on Earth that fit several wind regimes. To date only one GCM, that of Tokano (2008, 2010), has presented detailed analysis of its near surface winds and their dune forming capabilities. Despite the bulk of the wind being easterly, this GCM produces faster westerlies at equinox, thus transporting sand to the east. Our model, the Titan CAM (Friedson et al. 2009), is unable to reproduce the fast westerlies. Our GCM has been updated to include realistic topography released by the Cassini radar team. Preliminary results suggest our tropical wind regime now has net westerly winds in the tropics, albeit weak. References: Tokano, T. 2008. Icarus 194, 243-262. Tokano, T. 2010. Aeolian Research 2, 113-127. Friedson, J. et al. 2009. Planet. Sp. Sci., 57, 1931-1949.

Larson, Erik J.; Toon, O. B.; Friedson, A. J.

2013-10-01

232

An analysis of the current stability of the Dune Field at Great Sand Dunes National Monument using temporal TM imagery (1984–1998)  

Microsoft Academic Search

Research conducted at the Great Sand Dunes National Monument (37°46.5?N, 105°32.5?W) thus far has focused on dune composition in order to explain formation, dune migration to monitor aeolian processes, and dune extent to detect encroachment in the eastern periphery, a region that contains several visitor services. These studies used a series of field techniques in conjunction with aerial photography; however,

Jason R. Janke

2002-01-01

233

Dwelling in the Dunes: Traditional Use of the Dune Shacks of the Peaked Hill Bars Historic District, Cape Cod.  

National Technical Information Service (NTIS)

This ethnographic report provides a picture of the traditions and cultural patterns of the dune dwellers living in shacks in the Peaked Hill Bars Historic District, Cape Cod National Seashore, Massachusetts. The report describes the seasonal settlement of...

R. J. Wolfe

2005-01-01

234

Organic electrolyte for use in a lithium rechargeable electrochemical cell and lithium rechargeable electrochemical cell including said organic electrolyte  

SciTech Connect

This invention relates in general to use of an organic electrolyte in a lithium rechargeable electrochemical cell and to a lithium rechargeable electrochemical cell including said electrolyte; and, in particular, to the use of 1 to 2 mol/dm/sup 3/ LiAsF/sub 6/ in dimethylcarbonate (DMC) or 1 to 2 mol/dm/sup 3/ LiAsF/sub 6/ in (DMC) mixtures with methyl formate (MF) in which the mass percent of the (DMC) can vary from 25 to 100 mass percent as the electrolyte in a lithium rechargeable electrochemical cell, and to a lithium rechargeable electrochemical cell including said electrolyte.

Plichta, E.J.; Slane, S.M.; Salomon, M.

1987-07-06

235

Internal Structure of a Star Dune Imaged Using Ground-Penetrating Radar  

NASA Astrophysics Data System (ADS)

The Coral Pink Sand Dunes, located in far southwestern Kane County,Utah, is the site of an onging investigation into factors influencing dune field development. This elongate dune field (11 km by ~1.2 km) includes bedforms ranging along a continuum from stabilized sand sheets and vegetated parabolic dune forms to fully active transverse dunes and barchanoid ridges. This paper presents the results of our ground-penetrating radar (GPR) reconnaissance transects across a small star dune in the south central (active) portion of the dune field. GPR data (100 MHz, 1.0-meter offset, 0.5-meter step) were collected from four transects bracketing the star dune and provide radar imagery of the sedimentary structure of four arms of the dune and underlying bedrock. Processing of the GPR data consisted of a few steps, including dewowing and bandpass filtering, migration, and topographic correction. Results from data migration were mixed but overall did not appear to improve the imagery. Interpretations are made primarily from the unmigrated data cross-checked against the migrated dataset. Depth to bedrock ranges from 0 meters in the surrounding interdune serirs to 25 meters under the star dune crest. The shallow nature of the dune sands and a lack of major cross-stratification revealed in the cross sections suggest these dunes are still accumulating sand and respond quickly to changes in wind direction. The orientation of the foresets in the peak and main transverse dune arm imply the dune is presently responding to a southwesterly windflow. Southeasterward dipping foresets in three smaller (minor) arms longitudinal to the transverse dune possibly reflect modification of windflow around the main dune body. Comparison of aerial photography of the area from 1955 and 1960 with that of 1997 indicate the star dune formed through capture of another, smaller dune that merged from the southwest. The SE dipping foresets in the minor arms appear to reflect this capture, and so preserve both dune movement as well as windflow modification.

Wilkins, D. E.; Ford, R. L.; Clement, W. P.

2002-12-01

236

Challenges of Artificial Recharge at the Chain of Lakes  

NASA Astrophysics Data System (ADS)

A series of gravel quarry lakes, A through I (i.e. Chain of Lakes) in Alameda County, California are planned to convert to off-channel spreading lakes for artificial groundwater recharge. An operational plan is needed for the near-term improvements that would allow safe and efficient operations of Lake H and Lake I recently acquired for artificial recharge operations. Water source for the groundwater recharge comes from State Water Project (SWP) water releases at the South Bay Aqueduct turnout. The released water flows approximately nine miles in Arroyo Mocho Creek to the planned diversion facility. The recharge system includes multiple water delivery components and recharge components. Reliability of SWP water delivery is a water supply constraint to the recharge system. Hydraulic capacities of each delivery component and recharge capacities of each recharge component are physical constraints to the development of the operational plan. Policy issues identified in the Mitigated Negative Declaration which contains mitigation measures addressing potential impacts of fisheries and erosion are regulatory constraints to the operational plan development. Our approach that addresses technical challenges and policy issues in the development of the operational plan includes i) determination of lake recharge under observed conditions using water budget method; ii) development and calibration of a ground water flow model using MODFLOW; iii) estimation of lake recharge capacity for a range of lake levels using the calibrated ground water flow model; iv) analysis of clogging layer effects on recharge capacity; and v) development and application of operations models for the stream delivery system and the lake system.

Zeng, X.

2004-12-01

237

Porous silicon nanowires for lithium rechargeable batteries  

NASA Astrophysics Data System (ADS)

Porous silicon nanowire is fabricated by a simple electrospinning process combined with a magnesium reduction; this material is investigated for use as an anode material for lithium rechargeable batteries. We find that the porous silicon nanowire electrode from the simple and scalable method can deliver a high reversible capacity with an excellent cycle stability. The enhanced performance in terms of cycling stability is attributed to the facile accommodation of the volume change by the pores in the interconnect and the increased electronic conductivity due to a multi-level carbon coating during the fabrication process.

Yoo, Jung-Keun; Kim, Jongsoon; Lee, Hojun; Choi, Jaesuk; Choi, Min-Jae; Sim, Dong Min; Jung, Yeon Sik; Kang, Kisuk

2013-10-01

238

Porous silicon nanowires for lithium rechargeable batteries.  

PubMed

Porous silicon nanowire is fabricated by a simple electrospinning process combined with a magnesium reduction; this material is investigated for use as an anode material for lithium rechargeable batteries. We find that the porous silicon nanowire electrode from the simple and scalable method can deliver a high reversible capacity with an excellent cycle stability. The enhanced performance in terms of cycling stability is attributed to the facile accommodation of the volume change by the pores in the interconnect and the increased electronic conductivity due to a multi-level carbon coating during the fabrication process. PMID:24067596

Yoo, Jung-Keun; Kim, Jongsoon; Lee, Hojun; Choi, Jaesuk; Choi, Min-Jae; Sim, Dong Min; Jung, Yeon Sik; Kang, Kisuk

2013-09-25

239

Water-use dynamics of a peat swamp forest and a dune forest in Maputaland, South Africa  

NASA Astrophysics Data System (ADS)

Peat swamp forests are the second rarest forest type found in South Africa while dune forests have been under severe threat through mining and agriculture. Both forest types exist in the conservation area, and World Heritage site, known as the iSimangaliso Wetland Park on the East coast of South Africa. The area is prone to severe droughts (Taylor et al., 2006) and recent attempts to understand the local water-balance revealed that there was insufficient information on the water-use of the indigenous forests of the area. The Peat Swamp Forest and Dune Forest sites studied in this research were located within close proximity to each other, yet, are characterised by different landscape positions in terms of water availability. The coastal dune forest soil profile was generally dry and sandy and the trees' roots did not have access to the water table. In contrast the peat swamp forest is located in an interdunal wetland where the trees have permanent access to water. The climate at both sites is subtropical with a mean annual precipitation of 1200 mm yr-1. However, over 20 months of measurement, the first summer (October 2009 to March 2010) was drier (424 verses 735 mm) than the second summer (October 2010 to March 2011) emphasising the variability of the rainfall in the area and providing a wide range of conditions measured. The sapflow of an evergreen, overstory Syzygium cordatum and a semi-deciduous, understory Shirakiopsis elliptica were measured in the peat swamp forest using the heat ratio method. The Syzygium cordatum water-use was not highly seasonal and the daily maximum water-use ranged from approximately 30 L d-1 in winter to 45 L d-1 in summer whereas the Shirakiopsis elliptica water-use was more seasonal at 2 L d-1 in winter and 12 L d-1 in summer. The water-use of the Syzygium cordatum was not influenced by seasonal rainfall variations and was actually higher in the drier summer (October 2009 to March 2010). Three trees of different heights were monitored in the same way in the dune forest and the water-use found to be highly seasonal. Over the entire measurement period, the water-use was highest for an emergent Mimusops caffra (5 to 45 L d-1), whereas the water-use of the Eugenia natalitia (2 to 28 L d-1) and Drypetes natalensis (1 to 4 L d-1) was lower. At the dune forest, the water-use was highest in the wetter summer due to the reliance of the trees on rainfall to recharge the soil water. A split-line regression showed that on average, soil water limited tree water-use 64% of the time over the measurement period at the dune forest. For modeling tree water-use at the dune forest, it was concluded that a two-stage model, taking soil water content into account (from multiple sampling points), would be necessary.

Clulow, A. D.; Everson, C. S.; Price, J. S.; Jewitt, G. P. W.; Scott-Shaw, B. C.

2013-02-01

240

Recharge into Southern High Plains aquifer - Possible mechanisms, unresolved questions  

Microsoft Academic Search

The High Plains aquifer in the Southern High Plains (Texas and New Mexico), consisting of Tertiary, Cretaceous, and Triassic formations, has traditionally been considered to be recharged by its uppermost water-bearing unit the Tertiary Ogallala aquifer. This article provides hydrologic, chemical and isotopic evidence that in the Southern High Plains: (1) Cretaceous rocks actually contain independent recharge sources; (2) Triassic

Nativ

2009-01-01

241

Generator and rechargeable battery system for pedal powered vehicles  

Microsoft Academic Search

A generator and rechargeable battery system for use with pedal powered vehicles, such as bicycles, and where either the generator or battery can intermittently power a load such as a lighting system of the vehicle in one mode of operation, and in which the generator can recharge the battery in another mode of operation. A simple selection switch which is

Ryan

1985-01-01

242

Current collectors for rechargeable Li-Air batteries  

SciTech Connect

Here we report the negative influence of porous nickel foam for use as current collectors in rechargeable Li-air batteries. Uncoated nickel foam promotes the decomposition of LiPF6-organic carbonate electrolytes under normal charging conditions reported for rechargeable Li-air cells. We have identified Ni free porous carbon supports as more appropriate cathode current collectors.

Veith, Gabriel M [ORNL; Dudney, Nancy J [ORNL

2011-01-01

243

Hydrogeology of Regional Valley Fill Aquifers with Mountain System Recharge  

Microsoft Academic Search

Groundwater in the North Okanagan was investigated using an integrated physical, geochemical and numerical approach. The North Okanagan Groundwater Characterization and Assessment (NOGWCA) project began with an investigation of the geology and hydrostratigraphy of the North Okanagan region. The Deep Creek and Fortune Creek watersheds were found to contain multiple valley-fill aquifers which are recharged via mountain system recharge (MSR)

J. Ping; C. Nichol; A. Wei

2009-01-01

244

Intrinsically safe 5-V, 4-A rechargeable power supply  

Microsoft Academic Search

The U.S. Bureau of Mines has developed a regulated, intrinsically safe, rechargeable power supply for portable electronic equipment for underground use. The regulated output is ideal for microprocessor power requirements and is suited for operation in hazardous environments. Two rechargeable, sealed batteries are contained within the power supply. Provisions are made to use an external source of power if these

John J. Sammarco

1989-01-01

245

Comparative analysis of piezoelectric power harvesting circuits for rechargeable batteries  

Microsoft Academic Search

Using piezoelectric materials to harvest energy from ambient vibrations to power wireless sensors has been of great interest over the past few years. Due to the power output of the piezoelectric materials is relatively low, rechargeable battery is considered as one kind of energy storage to accumulate the harvested energy for intermittent use. Piezoelectric harvesting circuits for rechargeable batteries have

Mingjie Guan; Wei-Hsin Liao

2005-01-01

246

Transcutaneous Battery Recharging By Volume Conduction and its Circuit Modeling  

Microsoft Academic Search

Many implantable devices require large capacity batteries implanted in the body. Transcutaneous battery recharging can effectively maintain the longevity of these implants. Based on this consideration we have developed a transcutaneous battery recharging circuit unit which takes advantages of skin volume conduction. This unit is able to pass 2.8 mA from the outside to the inside of pig skin with

Zhide Tang; R. J. Sclabassi; C. Sun; S. A. Hackworth; Jun Zhao; X. T. Cui; M. Sun

2006-01-01

247

Computational Aspect of Artificial Ground Water Recharging into Unconfined Aquifer  

Microsoft Academic Search

CARE FOR GROUND WATER BEFORE IT BECOMES RARE therefore CATCHES WATER IN EVERY POSSIBLE WAY AND EVERY POSSIBLE PLACE IT FALLS. Mathematical aspect of ground water flow related to unconfined aquifer and a change in saturated thickness with variation in piezometric level so, permeability k, radius of influences L, distance between two recharge wells and presence of recharge by rainfall

Pratima Patel; M. D. Desai

248

Determining the recharge mode of Sahelian aquifers using water isotopes  

Microsoft Academic Search

It is proposed that the drainage network plays an important role in the recharge process of the fractured aquifers in the African Precambrian shield and that the fractured aquifer system is likely to be hydraulically continuous; this contrasts with most previous studies, which suggested direct recharge by rainwater percolation. Two areas were selected in Niger for the study of the

Pierre Girard; Claude Hillaire-Marcel; Marie Solange Oga

1997-01-01

249

Prototype systems for rechargeable magnesium batteries.  

PubMed

The thermodynamic properties of magnesium make it a natural choice for use as an anode material in rechargeable batteries, because it may provide a considerably higher energy density than the commonly used lead-acid and nickel-cadmium systems. Moreover, in contrast to lead and cadmium, magnesium is inexpensive, environmentally friendly and safe to handle. But the development of Mg batteries has been hindered by two problems. First, owing to the chemical activity of Mg, only solutions that neither donate nor accept protons are suitable as electrolytes; but most of these solutions allow the growth of passivating surface films, which inhibit any electrochemical reaction. Second, the choice of cathode materials has been limited by the difficulty of intercalating Mg ions in many hosts. Following previous studies of the electrochemistry of Mg electrodes in various non-aqueous solutions, and of a variety of intercalation electrodes, we have now developed rechargeable Mg battery systems that show promise for applications. The systems comprise electrolyte solutions based on Mg organohaloaluminate salts, and Mg(x)Mo3S4 cathodes, into which Mg ions can be intercalated reversibly, and with relatively fast kinetics. We expect that further improvements in the energy density will make these batteries a viable alternative to existing systems. PMID:11048714

Aurbach, D; Lu, Z; Schechter, A; Gofer, Y; Gizbar, H; Turgeman, R; Cohen, Y; Moshkovich, M; Levi, E

2000-10-12

250

Recharge and salinization in the Madrid Basin  

NASA Astrophysics Data System (ADS)

The purpose of this work was to reinvestigate the existing hydrogeological conceptual model of the basin of Madrid, Spain. A cumulative chemical isotopic diagram which enabled the distinction between different groups of water as well as calculation of the mode of their blending was used for this investigation. It was found that the groups of discharge were lighter in their isotopic composition than that of recharge. The previous explanation of this fact, backed by carbon-14 dating, was the long residence time due to flow lines going down to depths of more than 1000 m. This flow model assumes homogenous conditions to these depths. This assumption can not be supported by evidence from deep wells. Thus a modified model is suggested which maintains homogenous conditions only to about 300 m and a deep confined aquifer below containing paleowater. The higher degree of depletion of this water has been explained by a colder climate on top of an altitude effect. Another interesting observation was the correlation between the isotopic composition of the rains, the month of the rain event and the composition of the recharge group groundwater. It could be seen that the winter rains resemble the groundwater composition, which shows that practically all the spring and summer rains were evapotranspirated.

Issar, A. S.; Llamas, R. M.; Herraez, I.

1993-04-01

251

Titan's Yin-yang equator: dunes and Xanadu  

NASA Astrophysics Data System (ADS)

Two of Titan's most enigmatic geomorphological features, the dark dunes and the bright Xanadu terrain, encircle Titan's equator. They may bracket the time frame for persistence of surface features on Titan, so understanding their ages is important for evaluating Titan's surface history. Dunes, covering nearly 20% of Titan's surface, are rarely cut by other features and are thus among the youngest on Titan. Pattern analysis reveals current wind strengths and directions and contains information about past wind and sediment supply conditions. In contrast, the rugged Xanadu terrain contains the highest density of likely impact craters of any region on Titan, and thus is among the oldest terrains. Some of the most well-evolved river drainages on Titan are present in Xanadu, and reflect widespread and persistent precipitation and erosion, begun in the distant past and extending perhaps to the present day. As we broaden our vision beyond the study of individual geomorphic features, we seek to find a spatial and temporal connection between them. Dunes abut Xanadu on nearly all sides, and the presence of Xanadu affects the pattern of dunes for many hundreds of kilometers. Yet if dunes are younger than Xanadu and active, it is not clear why they do not invade its topographically subdued margins - perhaps sands are actively removed from the margins of Xanadu by fluvial processes. These processes, however, do not create dune-carving drainages, blur the dune structures or form obvious sand sinks. Piecing together the related evolution of these morphologically disparate yet spatially linked features is critical for creating a viable relative geological time scale for Titan.

Radebaugh, Jani; Lorenz, Ralph; Savage, Chris

2010-04-01

252

An areal recharge and discharge simulating method for MODFLOW  

NASA Astrophysics Data System (ADS)

As a widely used groundwater flow model, MODFLOW offers a set of packages to simulate hydrologic stresses, inflows and outflows, to a groundwater system. Speci?cally, MODFLOW lacks a general method to process areally distributed recharge and discharge to groundwater. One solution would be to create a new package for MODFLOW. Alternatively, it is also possible to make the best use of existing code to the same effect. In this note, a simple, yet effective method to simulate areal recharge and discharge is proposed based on the recharge (RCH) package of MODFLOW, allowing multiple instances of the RCH package to be used in one model. The method has been implemented in MODFLOW2000/2005 and has been successfully applied to a regional groundwater flow model to simulate areally distributed precipitation recharge, agricultural discharge and irrigation infiltration recharge in a simple approach.

Dong, Yanhui; Li, Guomin; Xu, Haizhen

2012-05-01

253

Groundwater Recharge Rate and Zone Structure Estimation Using PSOLVER Algorithm.  

PubMed

The quantification of groundwater recharge is an important but challenging task in groundwater flow modeling because recharge varies spatially and temporally. The goal of this study is to present an innovative methodology to estimate groundwater recharge rates and zone structures for regional groundwater flow models. Here, the unknown recharge field is partitioned into a number of zones using Voronoi Tessellation (VT). The identified zone structure with the recharge rates is associated through a simulation-optimization model that couples MODFLOW-2000 and the hybrid PSOLVER optimization algorithm. Applicability of this procedure is tested on a previously developed groundwater flow model of the Tahtal? Watershed. Successive zone structure solutions are obtained in an additive manner and penalty functions are used in the procedure to obtain realistic and plausible solutions. One of these functions constrains the optimization by forcing the sum of recharge rates for the grid cells that coincide with the Tahtal? Watershed area to be equal to the areal recharge rate determined in the previous modeling by a separate precipitation-runoff model. As a result, a six-zone structure is selected as the best zone structure that represents the areal recharge distribution. Comparison to results of a previous model for the same study area reveals that the proposed procedure significantly improves model performance with respect to calibration statistics. The proposed identification procedure can be thought of as an effective way to determine the recharge zone structure for groundwater flow models, in particular for situations where tangible information about groundwater recharge distribution does not exist. PMID:23746002

Ayvaz, M Tamer; Elçi, Alper

2013-06-01

254

Monitoring of desert dune topography by multi angle sensors  

NASA Astrophysics Data System (ADS)

Nowadays, the sandy desert is rapidly expanding world widely and results in a lot of risks in the socio-econimical aspects as well as the anthropogenic activities. For example, the increasing occurrences of mineral dust storm which presumably originated from the sandy deserts in northwest China become a serious threat in human activities as well as public health over Far East Asian area as the interpretation by the MODIS analysis (Zhang et al., 2007) and the particle trajectory simulation with HYSPLYT (HYbrid Single-Particle Lagrangian Integrated Trajectory) (Kim et al., 2011) identified. Since the sand dune activity has been recognized as an essential indicator of the progressive desertification, it is important to establish the monitoring method for the variations of topographic properties by the dune activities such as local roughness. Thus it will provide the crucial data about the extent and the transition of sandy desert. For example, it is well known the aerodynamic roughness lengths Zo which can be driven from the specialized sensor such as POLDER (POLarization and Directionality of the Earth's Reflectances) is essential to understand desert dune characteristics. However, for the multi temporal observation of dune fields, the availability of data set to extract Zo is limited. Therefore, we employed MISR (Multi angle imaging Spectro Radiometer) image sequence to extract multi angle topographic parameters such as NDAI (Normalized Difference Angular Index) or the variation of radiance with the viewing geometry which are representing the characteristics of target desert topography instead of Zo. In our approach, NDAI were expanded to the all viewing angles and then compared over the target sandy desert and the surrounding land covers. It showed very strong consistencies according to the land cover type and especially over the dynamic dune fields. On the other hands, the variation of NDAIs of sandy desert combining with the metrological observations were examined and showed a correlation between the intensities sand dune activities and the surface wind conditions. In conclusion, we proved that the trace of the sandy desert boundaries for long observation period is feasible with the multi angle orbital sensor observation by investigating the expanded NDAIs from various sample sand dune fields. However, it is quite uncertain whether the consistency of MISR NDAIs over sandy deserts originated from the aeolian micro structures, the reflectance of sand or the aspect angle of dune morphology. Therefore, in the next stage, the local roughness properties extracted from MISR data analysis will be compared with the topographic information from high resolution stereo satellite imagery such as ALOS PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping). Consequently it will correctly evaluate the suitability of multi angle observation parameters as a dune activity indicator.

Yun, J.; Kim, J.; Choi, Y.; Yun, H.

2011-12-01

255

Numerical modeling of the wind flow over a transverse dune  

PubMed Central

Transverse dunes, which form under unidirectional winds and have fixed profile in the direction perpendicular to the wind, occur on all celestial objects of our solar system where dunes have been detected. Here we perform a numerical study of the average turbulent wind flow over a transverse dune by means of computational fluid dynamics simulations. We find that the length of the zone of recirculating flow at the dune lee — the separation bubble — displays a surprisingly strong dependence on the wind shear velocity, u*: it is nearly independent of u* for shear velocities within the range between 0.2?m/s and 0.8?m/s but increases linearly with u* for larger shear velocities. Our calculations show that transport in the direction opposite to dune migration within the separation bubble can be sustained if u* is larger than approximately 0.39?m/s, whereas a larger value of u* (about 0.49?m/s) is required to initiate this reverse transport.

Araujo, Ascanio D.; Parteli, Eric J. R.; Poschel, Thorsten; Andrade, Jose S.; Herrmann, Hans J.

2013-01-01

256

Numerical modeling of the wind flow over a transverse dune  

NASA Astrophysics Data System (ADS)

Transverse dunes, which form under unidirectional winds and have fixed profile in the direction perpendicular to the wind, occur on all celestial objects of our solar system where dunes have been detected. Here we perform a numerical study of the average turbulent wind flow over a transverse dune by means of computational fluid dynamics simulations. We find that the length of the zone of recirculating flow at the dune lee -- the separation bubble -- displays a surprisingly strong dependence on the wind shear velocity, u*: it is nearly independent of u* for shear velocities within the range between 0.2 m/s and 0.8 m/s but increases linearly with u* for larger shear velocities. Our calculations show that transport in the direction opposite to dune migration within the separation bubble can be sustained if u* is larger than approximately 0.39 m/s, whereas a larger value of u* (about 0.49 m/s) is required to initiate this reverse transport.

Araújo, Ascânio D.; Parteli, Eric J. R.; Pöschel, Thorsten; Andrade, José S.; Herrmann, Hans J.

2013-10-01

257

Numerical modeling of the wind flow over a transverse dune.  

PubMed

Transverse dunes, which form under unidirectional winds and have fixed profile in the direction perpendicular to the wind, occur on all celestial objects of our solar system where dunes have been detected. Here we perform a numerical study of the average turbulent wind flow over a transverse dune by means of computational fluid dynamics simulations. We find that the length of the zone of recirculating flow at the dune lee - the separation bubble - displays a surprisingly strong dependence on the wind shear velocity, u*: it is nearly independent of u* for shear velocities within the range between 0.2?m/s and 0.8?m/s but increases linearly with u* for larger shear velocities. Our calculations show that transport in the direction opposite to dune migration within the separation bubble can be sustained if u* is larger than approximately 0.39?m/s, whereas a larger value of u* (about 0.49?m/s) is required to initiate this reverse transport. PMID:24091456

Araújo, Ascânio D; Parteli, Eric J R; Pöschel, Thorsten; Andrade, José S; Herrmann, Hans J

2013-10-04

258

Nanocarbon networks for advanced rechargeable lithium batteries.  

PubMed

Carbon is one of the essential elements in energy storage. In rechargeable lithium batteries, researchers have considered many types of nanostructured carbons, such as carbon nanoparticles, carbon nanotubes, graphene, and nanoporous carbon, as anode materials and, especially, as key components for building advanced composite electrode materials. Nanocarbons can form efficient three-dimensional conducting networks that improve the performance of electrode materials suffering from the limited kinetics of lithium storage. Although the porous structure guarantees a fast migration of Li ions, the nanocarbon network can serve as an effective matrix for dispersing the active materials to prevent them from agglomerating. The nanocarbon network also affords an efficient electron pathway to provide better electrical contacts. Because of their structural stability and flexibility, nanocarbon networks can alleviate the stress and volume changes that occur in active materials during the Li insertion/extraction process. Through the elegant design of hierarchical electrode materials with nanocarbon networks, researchers can improve both the kinetic performance and the structural stability of the electrode material, which leads to optimal battery capacity, cycling stability, and rate capability. This Account summarizes recent progress in the structural design, chemical synthesis, and characterization of the electrochemical properties of nanocarbon networks for Li-ion batteries. In such systems, storage occurs primarily in the non-carbon components, while carbon acts as the conductor and as the structural buffer. We emphasize representative nanocarbon networks including those that use carbon nanotubes and graphene. We discuss the role of carbon in enhancing the performance of various electrode materials in areas such as Li storage, Li ion and electron transport, and structural stability during cycling. We especially highlight the use of graphene to construct the carbon conducting network for alloy anodes, such as Si and Ge, to accelerate electron transport, alleviate volume change, and prevent the agglomeration of active nanoparticles. Finally, we describe the power of nanocarbon networks for the next generation rechargeable lithium batteries, including Li-S, Li-O(2), and Li-organic batteries, and provide insights into the design of ideal nanocarbon networks for these devices. In addition, we address the ways in which nanocarbon networks can expand the applications of rechargeable lithium batteries into the emerging fields of stationary energy storage and transportation. PMID:22953777

Xin, Sen; Guo, Yu-Guo; Wan, Li-Jun

2012-09-06

259

Unlinkable Priced Oblivious Transfer with Rechargeable Wallets  

NASA Astrophysics Data System (ADS)

We present the first truly unlinkable priced oblivious transfer protocol. Our protocol allows customers to buy database records while remaining fully anonymous, i.e., (1) the database does not learn who purchases a record, and cannot link purchases by the same customer; (2) the database does not learn which record is being purchased, nor the price of the record that is being purchased; (3) the customer can only obtain a single record per purchase, and cannot spend more than his account balance; (4) the database does not learn the customer's remaining balance. In our protocol customers keep track of their own balances, rather than leaving this to the database as done in previous protocols. Our priced oblivious transfer protocol is also the first to allow customers to (anonymously) recharge their balances. Finally, we prove our protocol secure in the standard model (i.e., without random oracles).

Camenisch, Jan; Dubovitskaya, Maria; Neven, Gregory

260

Solid polymer electrolytes for rechargeable batteries  

NASA Astrophysics Data System (ADS)

SRI International has synthesized and tested new, dimensionally stable polymer electrolytes for high energy density rechargeable lithium batteries. We have prepared semi-interpenetrating networks of sulfur-substituted polyethyleneoxide with tetraethylorthosilicate (TEOS). The in situ hydrolysis of TEOS produces a mechanically stable three-dimensional network that entangles the polymer electrolytes and makes the film dimensionally flexible and stable. With this approach, the best dimensionally stable polymer electrolyte of this type produced so far, has a room temperature lithium ion conductivity of 7.5 x 10(exp -4) S cm(exp -1). Another type of solid polymer electrolytes, polydiacetylene-based single-ion conductors with high room temperature proton conductivity were also developed. The best conductivity of these polymers is two orders of magnitude higher than that of Nafion under comparable experimental conditions. With further appropriate chemical modification, the new polymers could be used in fuel cells.

Narang, Subhash C.; Ventura, Susanna C.

1992-02-01

261

Spinel electrodes for rechargeable lithium batteries.  

SciTech Connect

This paper gives a historical account of the development of spinel electrodes for rechargeable lithium batteries. Research in the late 1970's and early 1980's on high-temperature . Li/Fe{sub 3}O{sub 4} cells led to the evaluation of lithium spinels Li[B{sub 2}]X{sub 4} at room temperature (B = metal cation). This work highlighted the importance of the [B{sub 2}]X{sub 4}spinel framework as a host electrode structure and the ability to tailor the cell voltage by selection of different B cations. Examples of lithium-ion cells that operate with spinel anode/spinel cathode couples are provided. Particular attention is paid to spinels within the solid solution system Li{sub 1+x}Mn{sub 2-x}O{sub 4} (0 {le} x {le} 0.33).

Thackeray, M. M.

1999-11-10

262

[Effects of reclaimed water recharge on groundwater quality: a review].  

PubMed

Reclaimed water recharge to groundwater is an effective way to relieve water resource crisis. However, reclaimed water contains some pollutants such as nitrate, heavy metals, and new type contaminants, and thus, there exists definite environmental risk in the reclaimed water recharge to groundwater. To promote the development of reclaimed water recharge to groundwater and the safe use of reclaimed water in China, this paper analyzed the relevant literatures and practical experiences around the world, and summarized the effects of different reclaimed water recharge modes on the groundwater quality. Surface recharge makes the salt and nitrate contents in groundwater increased but the risk of heavy metals pollution be smaller, whereas well recharge can induce the arsenic release from sedimentary aquifers, which needs to be paid more attention to. New type contaminants are the hotspots in current researches, and their real risks are unknown. Pathogens have less pollution risks on groundwater, but some virus with strong activity can have the risks. Some suggestions were put forward to reduce the risks associated with the reclaimed water recharge to groundwater in China. PMID:24015541

Chen, Wei-Ping; Lü, Si-Dan; Wang, Mei-E; Jiao, Wen-Tao

2013-05-01

263

Using atmospheric tracers to reduce uncertainty in groundwater recharge areas.  

PubMed

A Monte Carlo-based approach to assess uncertainty in recharge areas shows that incorporation of atmospheric tracer observations (in this case, tritium concentration) and prior information on model parameters leads to more precise predictions of recharge areas. Variance-covariance matrices, from model calibration and calculation of sensitivities, were used to generate parameter sets that account for parameter correlation and uncertainty. Constraining parameter sets to those that met acceptance criteria, which included a standard error criterion, did not appear to bias model results. Although the addition of atmospheric tracer observations and prior information produced similar changes in the extent of predicted recharge areas, prior information had the effect of increasing probabilities within the recharge area to a greater extent than atmospheric tracer observations. Uncertainty in the recharge area propagates into predictions that directly affect water quality, such as land cover in the recharge area associated with a well and the residence time associated with the well. Assessments of well vulnerability that depend on these factors should include an assessment of model parameter uncertainty. A formal simulation of parameter uncertainty can be used to delineate probabilistic recharge areas, and the results can be expressed in ways that can be useful to water-resource managers. Although no one model is the correct model, the results of multiple models can be evaluated in terms of the decision being made and the probability of a given outcome from each model. PMID:21416662

Starn, J Jeffrey; Bagtzoglou, Amvrossios C; Robbins, Gary A

264

Quantifying the modern recharge of the "fossil" Sahara aquifers  

NASA Astrophysics Data System (ADS)

The North-Western Sahara Aquifer System (NWSAS), one of the world's largest groundwater systems, shows an overall piezometric decline associated with increasing withdrawals. Estimating the recharge rate in such a semiarid system is challenging but crucial for sustainable water development. In this paper, the recharge of the NWSAS is estimated using a regional water budget based on GRACE terrestrial water storage monthly records, soil moisture from the GLDAS (a land data system that assimilates hydrological information), and groundwater pumping rates. A cumulated natural recharge rate of 1.40 ± 0.90 km3 yr-1is estimated for the two main aquifers. Our results suggest a renewal rate of about 40% which partly contradicts the premise that recharge in this area should be very low or even null. Aquifer depletion inferred from our analysis is consistent with observed piezometric head decline in the two main aquifers in the region. Annual recharge variations were also estimated and vary between 0 and 4.40 km3 yr-1for the period 2003-2010. These values correspond to a recharge between 0 and 6.75 mm yr-1 on the 650,000 km2of outcropping areas of the aquifers, which is consistent with the expected weak and sporadic recharge in this semiarid environment. These variations are also in line with annual rainfall variation with a lag time of about 1 year.

GonçAlvèS, J.; Petersen, J.; Deschamps, P.; Hamelin, B.; Baba-Sy, O.

2013-06-01

265

Geostatistical estimates of future recharge for the Death Valley region  

SciTech Connect

Spatially distributed estimates of regional ground water recharge rates under both current and potential future climates are needed to evaluate a potential geologic repository for high-level nuclear waste at Yucca Mountain, Nevada, which is located within the Death Valley ground-water region (DVGWR). Determining the spatial distribution of recharge is important for regional saturated-zone ground-water flow models. In the southern Nevada region, the Maxey-Eakin method has been used for estimating recharge based on average annual precipitation. Although this method does not directly account for a variety of location-specific factors which control recharge (such as bedrock permeability, soil cover, and net radiation), precipitation is the primary factor that controls in the region. Estimates of recharge obtained by using the Maxey-Eakin method are comparable to estimates of recharge obtained by using chloride balance studies. The authors consider the Maxey-Eakin approach as a relatively simple method of obtaining preliminary estimates of recharge on a regional scale.

Hevesi, J.A. [Geological Survey, Las Vegas, NV (United States); Flint, A.L. [Geological Survey, Sacramento, CA (United States)

1998-12-01

266

Aquifer recharging in South Carolina: radiocarbon in environmental hydrogeology  

SciTech Connect

Radiocarbon activities of dissolved inorganic carbon (and tritium activities where infiltration rates are rapid and aquifers shallow) provide relatively unambiguous and inexpensive evidence for identification of significant recharge areas. Such evidence is for the actual occurrence of modern recharge in the aquifer and thus is less inferential than stratigraphic or potentiometric evidence. These underutilized isotopic techniques are neither arcane nor complex and have been more-or-less standardized by earlier researchers. In South Carolina, isotopic evidence has been used from both calcareous and siliceous sedimentary aquifers and fractured crystalline rock aquifers. The Tertiary limestone aquifer is shown not to be principally recharged in its subcrop area, unlike conditions assumed for many other sedimentary aquifers in southeastern United States, and instead receives considerable lateral recharge from interfingering updip Tertiary sand aquifers in the middle coastal plain. Induced recharging at Hilton Head Island is mixing ancient relict water and modern recharge water. Recharging to deeper portions of the Cretaceous Middendorf basal sand aquifer occurs at least as far coastward as the middle coastal plain, near sampling sites that stratigraphically appear to be confined. Pronounced mineralization of water in fractured rocks cannot be considered as evidence of ancient or relict ground water that is isolated from modern contaminants, some of these waters contain considerable radiocarbon and hydrogen-bomb tritium.

Stone, P.A.; Knox, R.L.; Mathews, T.D.

1985-01-01

267

Effects of trampling limitation on coastal dune plant communities.  

PubMed

Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1–2 years) and effective method for improving and safeguarding the diversity of dune plant communities. PMID:22302225

Santoro, Riccardo; Jucker, Tommaso; Prisco, Irene; Carboni, Marta; Battisti, Corrado; Acosta, Alicia T R

2012-03-01

268

Effects of Trampling Limitation on Coastal Dune Plant Communities  

NASA Astrophysics Data System (ADS)

Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1-2 years) and effective method for improving and safeguarding the diversity of dune plant communities.

Santoro, Riccardo; Jucker, Tommaso; Prisco, Irene; Carboni, Marta; Battisti, Corrado; Acosta, Alicia T. R.

2012-03-01

269

Aeolian dunes as ground truth for atmospheric modeling on Mars  

USGS Publications Warehouse

Martian aeolian dunes preserve a record of atmosphere/surface interaction on a variety of scales, serving as ground truth for both Global Climate Models (GCMs) and mesoscale climate models, such as the Mars Regional Atmospheric Modeling System (MRAMS). We hypothesize that the location of dune fields, expressed globally by geographic distribution and locally by dune centroid azimuth (DCA), may record the long-term integration of atmospheric activity across a broad area, preserving GCM-scale atmospheric trends. In contrast, individual dune morphology, as expressed in slipface orientation (SF), may be more sensitive to localized variations in circulation, preserving topographically controlled mesoscale trends. We test this hypothesis by comparing the geographic distribution, DCA, and SF of dunes with output from the Ames Mars GCM and, at a local study site, with output from MRAMS. When compared to the GCM: 1) dunes generally lie adjacent to areas with strongest winds, 2) DCA agrees fairly well with GCM modeled wind directions in smooth-floored craters, and 3) SF does not agree well with GCM modeled wind directions. When compared to MRAMS modeled winds at our study site: 1) DCA generally coincides with the part of the crater where modeled mean winds are weak, and 2) SFs are consistent with some weak, topographically influenced modeled winds. We conclude that: 1) geographic distribution may be valuable as ground truth for GCMs, 2) DCA may be useful as ground truth for both GCM and mesoscale models, and 3) SF may be useful as ground truth for mesoscale models. Copyright 2009 by the American Geophysical Union.

Hayward, R. K.; Titus, T. N.; Michaels, T. I.; Fenton, L. K.; Colaprete, A.; Christensen, P. R.

2009-01-01

270

Echo Meadows Project Winter Artificial Recharge.  

SciTech Connect

This report discusses the findings of the Echo Meadows Project (BPA Project 2001-015-00). The main purpose of this project is to artificially recharge an alluvial aquifer, WITH water from Umatilla River during the winter high flow period. In turn, this recharged aquifer will discharge an increased flow of cool groundwater back to the river, thereby improving Umatilla River water quality and temperature. A considerable side benefit is that the Umatilla River should improve as a habitat for migration, spanning, and rearing of anadromous and resident fish. The scope of this project is to provide critical baseline information about the Echo Meadows and the associated reach of the Umatilla River. Key elements of information that has been gathered include: (1) Annual and seasonal groundwater levels in the aquifer with an emphasis on the irrigation season, (2) Groundwater hydraulic properties, particularly hydraulic conductivity and specific yield, and (3) Groundwater and Umatilla River water quality including temperature, nutrients and other indicator parameters. One of the major purposes of this data gathering was to develop input to a groundwater model of the area. The purpose of the model is to estimate our ability to recharge this aquifer using water that is only available outside of the irrigation season (December through the end of February) and to estimate the timing of groundwater return flow back to the river. We have found through the data collection and modeling efforts that this reach of the river had historically returned as much as 45 cubic feet per second (cfs) of water to the Umatilla River during the summer and early fall. However, this return flow was reduced to as low as 10 cfs primarily due to reduced quantities of irrigation application, gain in irrigation efficiencies and increased groundwater pumping. Our modeling indicated that it is possible to restore these critical return flows using applied water outside of the irrigation season. We further found that this water can be timed to return to the river during the desired time of the year (summer to early fall). This is because the river stage, which remains relatively high until this time, drops during the irrigation season-thereby releasing the stored groundwater and increasing river flows. A significant side benefit is that these enhanced groundwater return flows will be clean and cold, particularly as compared to the Umatilla River. We also believe that this same type of application of water could be done and the resulting stream flows could be realized in other watersheds throughout the Pacific Northwest. This means that it is critical to compare the results from this baseline report to the full implementation of the project in the next phase. As previously stated, this report only discusses the results of data gathered during the baseline phase of this project. We have attempted to make the data that has been gathered accessible with the enclosed databases and spreadsheets. We provide computer links in this report to the databases so that interested parties can fully evaluate the data that has been gathered. However, we cannot emphasize too strongly that the real value of this project is to implement the phases to come, compare the results of these future phases to this baseline and develop the science and strategies to successfully implement this concept to other rivers in the Pacific Northwest. The results from our verified and calibrated groundwater model matches the observed groundwater data and trends collected during the baseline phase. The modeling results indicate that the return flows may increase to their historic values with the addition of 1 acre-ft/acre of recharge water to the groundwater system (about 9,600 acre-feet total). What this means is that through continued recharge project, you can double to quadruple the annual baseflow of the Umatilla River during the low summer and fall flow periods as compared to the present base-flow. The cool and high quality recharge water is a significant beneficial impact to the river system.

Ziari, Fred

2002-12-19

271

Effects of artificial recharge on the Ogallala aquifer, Texas  

USGS Publications Warehouse

Four recharge tests were conducted by injecting water from playa lakes through wells into the Ogallala Formation. Injection was by gravity flow and by pumping under pressure. At one site, 34-acre feet of water was injected by gravity and produced a significant increase in yield of the well. At a second site, gravity injection of only 0.58 acre-foot caused a significant decrease in permeability due to plugging by suspended sediment. At two other sites, injection by pumping 6 and 14 acre-feet respectively, resulted in discharge of water at the surface and in perching of water above the water table. Differences in success of recharge were largely due to aquifer lithology and, therefore, the type of permeability; the concentration of suspended solids in the recharge water; and the injection technique. The injection technique can be controlled and the concentration of suspended solids can be minimized by treatment, but the site for well recharge will accept water most rapidly if it is selected on the basis of a favorable geohydrologic environment. Geophysical logs were used to study the effect of aquifer lithology on recharge and to understand the movement of injected water. Temperature logs were particularly useful in tracing the movement of recharged water. Natural-gamma, gamma-gamma, and neutron logs provided important data on lithology and porosity in the aquifer and changes in porosity and water distribution resulting from recharge. Effective recharge of the Ogallala Formation, using water from playa lakes, is possible where geohydrologic conditions are favorable and the recharge system is properly constructed.

Brown, Richmond Flint; Keys, W. S.

1985-01-01

272

Origin of Titan's dunes: noncohesive sand in bidirectional winds or sticky sand in unidirectional winds?  

NASA Astrophysics Data System (ADS)

Eolian dunes occur on Earth, Venus, Mars, and Titan, distinguishing them as one of the more widespread landforms in the solar system. On Earth, unidirectional winds blowing over loose, noncohesive sand produce crescentic-shaped dunes with crests oriented normal to the sand-transport direction (transverse dunes), but roughly half of Earth's large deserts are covered with longer-crested dunes (linear dunes) that are commonly oriented parallel or oblique to the resultant sand-transport vector (longitudinal dunes and oblique dunes, respectively). Such linear dunes form in at least two situations: (1) directionally bimodal winds blowing over loose sand, and (2) unimodal winds blowing over sediment that is vegetated, cohesive, sheltered by upwind topography, or otherwise locally stabilized. This study documents an example (Qaidam Basin, China) where a downwind increase in sediment cohesiveness (due to salt and mud incorporated from the local land surface) causes dunes to change orientation from transverse to longitudinal, and the work presents a compilation of related situations where stabilization of dune sediment has been reported to produce linear dunes. This family of stabilized dunes functions dynamically as self-extending "sand-shadow" or lee dunes. Loose sediment accumulates locally on these dunes, where it becomes stabilized, thereby allowing the dune itself to function as an obstacle that induces subsequent deposition farther downwind. Linear dunes on Titan previously have been interpreted as forming in the first situation listed above: bimodal winds blowing over loose sand. Because Titan's sand is believed to be composed of hydrocarbons or nitriles, however, the hypothesized loose, non-sticky nature of the sand has surprised researchers. In addition, the previous hypothesis of bimodal winds requires that north-south tidal flow be stronger than west-east zonal flow, which also was unexpected. The new hypothesis presented here—that Titan's dunes formed by unidirectional winds blowing over cohesive or sticky sand—resolves these two puzzles, cannot be ruled out with existing observations, and has grossly different implications regarding Titan's sediment properties, surface moisture, and wind regime. Satellite image of dunes in the Qaidam Basin, China. Change in sediment properties causes a change from transverse to longitudinal orientation of the dunes. Transverse dunes are higher in elevation than the longitudinal dunes and composed of noncohesive sand. Longitudinal dunes are cemented with silt, clay, and salt acquired locally.

Rubin, D. M.

2009-12-01

273

Ground-water recharge from streamflow data, NW Florida  

USGS Publications Warehouse

Annual base flows of streams draining Okaloosa County and adjacent areas in northwest Florida were determined through hydrograph separation and correlation techniques for purposes of evaluating variations in ground-water recharge rates. Base flows were least in the northern part of the county and greatest in the southern part. Topographic and soils data were then superimposed on the distribution of base flow by subbasin to produce a map showing distribution of ground-water recharge throughout the county. The highest recharge rate occurs in the southern part of the county where relatively flat upland areas underlain by excessively drained sandy soils result in minimal storm runoff and evapotranspiration.

Vecchioli, John; Bridges, W. C.; Rumenik, R. P.; Grubbs, J. W.

1991-01-01

274

Cassini SAR, radiometry, scatterometry and altimetry observations of Titan’s dune fields  

Microsoft Academic Search

Large expanses of linear dunes cover Titan’s equatorial regions. As the Cassini mission continues, more dune fields are becoming unveiled and examined by the microwave radar in all its modes of operation (SAR, radiometry, scatterometry, altimetry) and with an increasing variety of observational geometries. In this paper, we report on Cassini’s radar instrument observations of the dune fields mapped through

A. Le Gall; M. A. Janssen; L. C. Wye; A. G. Hayes; J. Radebaugh; C. Savage; H. Zebker; R. D. Lorenz; J. I. Lunine; R. L. Kirk; R. M. C. Lopes; S. Wall; P. Callahan; E. R. Stofan; T. Farr

2011-01-01

275

Soil nutrients are not responsible for arrested succession in disturbed coastal dune forest  

Microsoft Academic Search

Coastal dune forest succession frequently proceeds via the Acacia karroo pathway, but may become arrested. We examine whether soil fertility arrests forest succession in A. karroo stands in coastal dune forest in KwaZulu-Natal province, South Africa. We examined soil fertility of A. karroo stands, the adjacent forest, and forested dune slacks at Cape Vidal, and four rehabilitating A. karroo stands

L. J. Boyes; M. E. Griffiths; A. D. Manson; M. J. Lawes

2010-01-01

276

Lunette dunes in the northeast Cape, South Africa, as geomorphic indicators of palaeoenvironmental change  

Microsoft Academic Search

Three lunette dunes occur on the southern shore of a pan on the farm Buffelsfontein above the Great Escarpment in the northeastern part of the Eastern Cape Province, South Africa. The two inner lunettes are formed of silt and clay, and the third of fine sand. The location of these dunes is anomalous as lunette dunes are rare in the

M. E. Marker; P. J. Holmes

1995-01-01

277

Rare earth elements of the Altar Desert dune and coastal sands, Northwestern Mexico  

Microsoft Academic Search

Twenty-one surficial sand samples from the Altar Desert coastal and desert dune systems were analysed for rare earth elements (REE) content. This was done to observe the provenance signatures for four strategic dune localities near the Colorado River Delta, the El Pinacate dune fields, and the beaches of the north of the Gulf of California in the state of Sonora,

Juan José Kasper-Zubillaga; Beatriz Acevedo-Vargas; Ofelia Morton Bermea; Glicinia Ortiz Zamora

2008-01-01

278

Responses of dune mosses to experimental burial by sand under natural and greenhouse conditions  

Microsoft Academic Search

Sand movement is a predominant feature of mobile coastal and lake-shoreline sand dunes. Plants growing in these environments are able to withstand and survive periods of burial by sand. Although mosses are important dune stabilizers in temperate dunes, there are few studies focused on their response to burial by sand. In this study we examined the effects of burial by

M. Luisa Martínez; M. A. Maun

1999-01-01

279

Uncertainty Assessment for Numerical Modeling of Dune and Backshore Evolution Under Sea-Level Rise Scenarios  

Microsoft Academic Search

The beach dunes play an essential role in the evolution of barrier island shapes and coastlines. The dunes protect the beaches and beach ecology by absorbing energy from the storms and provide sediment to the beaches or backshores when erosion occurs. While a number of models have been developed to simulate the evolution of dunes and backshores, few of the

H. Dai; M. Ye; A. W. Niedoroda; S. Kish; J. F. Donoghue; B. Saha

2010-01-01

280

Soil Water Balance and Recharge Monitoring at the Hanford Site – FY 2010 Status Report  

SciTech Connect

This report summarizes the recharge data collected in FY 2010 at five locations on the Hanford Site in southeastern Washington State. Average monthly precipitation and temperature conditions in FY 2010 were near normal and did not present an opportunity for increased recharge. The recharge monitoring data confirmed those conditions, showing normal behavior in water content, matric head, and recharge rates. Also provided in this report is a strategy for recharge estimation for the next 5 years.

Fayer, Michael J.; Saunders, Danielle L.; Herrington, Ricky S.; Felmy, Diana

2010-10-27

281

GROUNDWATER RECHARGE/DISCHARGE, NEUSE RIVER WATERSHED, NC  

EPA Science Inventory

The North Carolina Department of Environment and Natural Resources, Division of Water Quality and Groundwater Section, in cooperation with the NC Center for Geographic Information and Analysis, developed the Groundwater Recharge/Discharge digital data to enhance planning, siting ...

282

Recharging of contaminated aquifer with reclaimed sewage water  

NASA Astrophysics Data System (ADS)

About 40% of the water supply of Cairo, Egypt, is drawn from a groundwater reservoir located southeast of the Nile Delta. Several thousand shallow wells supply drinking water to the farmers from the same groundwater reservoir, which is recharged by seepage from Ismailia canal, the irrigation canal network, and other wastewater lagoons in the same areas. Sewage water lagoons were located at the high ground of the area, recharging contaminated water into the aquifer. Since the groundwater in this area is used for drinking purposes, it was decided to treat the sewage water recharging the aquifer for health reasons. In this paper a solution to the problem is presented using an injection well recharging good quality water into the aquifer. A pumping well located at a distance downstream is used to pump the contaminated water out of the aquifer. A three-dimensional solute transport model was developed to study the concentration distribution with remediation time in the contaminated zone.

Soliman, M. M.; El-Din, M. Nour; Hassan, N. A.

1995-04-01

283

Solid polymer electrolytes for rechargeable batteries. Final report.  

National Technical Information Service (NTIS)

SRI International has synthesized and tested new, dimensionally stable polymer electrolytes for high energy density rechargeable lithium batteries. We have prepared semi-interpenetrating networks of sulfur-substituted polyethyleneoxide with tetmethylortho...

S. C. Narang S. C. Ventura

1992-01-01

284

Intrinsically Safe 5-V, 4-A: Rechargeable Power Supply.  

National Technical Information Service (NTIS)

The U.S. Bureau of Mines has developed a regulated, intrinsically safe, rechargeable power supply for portable electronic equipment for underground use. The regulated output is ideal for microprocessor power requirements and is suited for operation in haz...

J. J. Sammarco

1989-01-01

285

Lithium Rechargeable Cell With a Poly 3-Methylthiophene Cathode.  

National Technical Information Service (NTIS)

A poly 3-methylthiophene (PMT) cathode showed excellent coulombic efficiency during cycling in a lithium rechargeable cell. An electrolyte containing dimethyl carbonate was used since it is stable at the high anodic potentials reached during cell charging...

C. W. Walker S. M. Slane

1992-01-01

286

Spatial and temporal variations in seepage during managed aquifer recharge  

NASA Astrophysics Data System (ADS)

Managed aquifer recharge (MAR) is an increasingly important means of supplementing fresh water resources and helping to limit ground water overdraft. Many MAR systems are operated above a vadose zone and usually recharge rapidly during an initial phase of diversion. Recharge typically slows considerably within subsequent weeks to months as sedimentation, biofouling, soil compaction, drainage at the base of the wetting front, and other processes reduce the hydraulic conductance below the percolation pond. Studies of such systems provide controlled windows into subsurface conditions and processes, vital both for improving MAR efficiency and generating better understanding of recharge processes in general. We instrumented a 3 ha MAR pond above a shallow aquifer in central coastal California, to quantify variations in rates and locations of recharge, and to measure changes in soil properties with time during a recharge season. Using heat as a tracer of fluid flow, we utilize data recorded by autonomous temperature loggers installed in the base of the pond to calculate point-specific seepage rates based on time-series analysis. Pressure loggers installed in the same locations allow quantification of head gradients with time. By combining gradient and seepage data, we determine absolute values of the hydraulic conductance of the saturated soil at the base of the pond, including changes in these values with time. Point-specific seepage rates vary enormously throughout the recharge cycle and across the pond base. Areas with rapid initial seepage rates exceeding 5 m d-1 decrease abruptly to <0.1 m d-1 after the first few weeks of MAR operation. Conversely, seepage rates in areas which are virtually stagnant at the onset of recharge increase to >0.5 m d-1 after several months, accounting for the majority of late-season recharge. In effect, the locus of seepage assumes the form of a kinematic wave as it propagates laterally with time across the pond bed. Seepage appears to correlate with soil type, with areas of initial rapid seepage corresponding to more coarsely grained soils, and later recharge occurring in areas overlying significantly finer material. Collection of soil samples before and after the seepage season, as well as geochemical data from the aquifer below the pond, help to resolve the fraction of the pond, and hence the subsurface conditions, that contribute most to recharge.

Racz, A. J.; Fisher, A. T.; Schmidt, C. M.; Lockwood, B. S.; Los Huertos, M.

2009-12-01

287

Similarities of Tritonian guttae and Martian dark dune spots  

NASA Astrophysics Data System (ADS)

Dark spots with bright halo near the edge of the Triton's photographed south polar cap and Martian Dark Dune Spots (DDS) sometimes with bright halo, found at the Martian circumpolar regions show striking morphological similarities which may imply similar formative processes.

Hargitai, H. I.

2012-09-01

288

Alphabetisation conscientisante comme base d'une education permanente  

NASA Astrophysics Data System (ADS)

D'après la pratique et les enseignements vécus, nous pensons qu'une alphabétisation fonctionnelle et conscientisante est susceptible de constituer la base d'une éducation permanente (life long education), à condition que: Une philosophie et une anthropologie de la libération de l'homme soient le fondement de 1'alphabétisation;

Ndimurukundo, Nicephore

1994-05-01

289

SIMULTANEOUS SIDE BY SIDE VARIABILITY OF SEDIMENT CONCENTRATION OVER DUNES  

Technology Transfer Automated Retrieval System (TEKTRAN)

A series of laboratory experiments were conducted in a laboratory flume to characterize the lateral variations of suspended sediment over dunes. Forty experimental runs were made using flow depths of 0.33 and 0.13 m in a 1.2 m wide flume channel. The Froude number was 0.5 and the median diameter of...

290

A parameterization of flow separation over subaqueous dunes  

NASA Astrophysics Data System (ADS)

Flow separation plays a key role in the development of dunes, and modeling the complicated flow behavior inside the flow separation zone requires much computational effort. To make a first step toward modeling dune development at reasonable temporal and spatial scales, a parameterization of the shape of the flow separation zone over two-dimensional dunes is proposed herein, in order to avoid modeling the complex flow inside the flow separation zone. Flow separation behind dunes, with an angle-of-repose slip face, is characterized by a large circulating leeside eddy, where a separation streamline forms the upper boundary of the recirculating eddy. Experimental data of turbulent flow over two-dimensional subaqueous bed forms are used to parameterize this separation streamline. The bed forms have various heights and height to length ratios, and a wide range of flow conditions is analyzed. This paper shows that the shape of the flow separation zone can be approximated by a third-order polynomial as a function of the distance away from the flow separation point. The coefficients of the polynomial can be estimated, independent of flow conditions, on the basis of bed form shape at the flow separation point and a constant angle of the separation streamline at the flow reattachment point.

Paarlberg, Andries J.; Dohmen-Janssen, C. Marjolein; Hulscher, Suzanne J. M. H.; Termes, Paul

2007-12-01

291

Analysis of Coastal Dunes: A Remote Sensing and Statistical Approach.  

ERIC Educational Resources Information Center

Remote sensing analysis and statistical methods were used to analyze the coastal dunes of Plum Island, Massachusetts. The research methodology used provides an example of a student project for remote sensing, geomorphology, or spatial analysis courses at the university level. (RM)

Jones, J. Richard

1985-01-01

292

Comment on ``Minimal size of a barchan dune''  

Microsoft Academic Search

It is now an accepted fact that the size at which dunes form from a flat sand bed as well as their ``minimal size'' scales on the flux saturation length. This length is by definition the relaxation length of the slowest mode toward equilibrium transport. The model presented by Parteli, Durán, and Herrmann [Phys. Rev. E 75, 011301 (2007)] predicts

B. Andreotti; P. Claudin

2007-01-01

293

Luminescence studies of dunes from North-Eastern Tasmania  

Microsoft Academic Search

Northern Tasmania has a geographically extensive cover of Quaternary aeolian features and although the morphology and stratigraphy of many of these have been studied it is difficult to assign a reliable chronology because of the lack of material suitable for radiocarbon dating. The dunes are primarily composed of quartz and hence are ideally suited for the application of luminescence dating.

G. A. T. Duller; P. Augustinus

1997-01-01

294

Population biology of salt marsh and sand dune annuals  

Microsoft Academic Search

Annuals represent a significant component of the vegetation of coastal salt marshes and sand dunes. From many points of view, the two habitats might appear to have little in common. Yet both are characterized by episodes of low water potential, marked spatial and temporal heterogeneity and a zonation which, within certain limits, reflects successional change.

A. R. Watkinson; A. J. Davy

1985-01-01

295

Predicting flooding probability for beach\\/dune systems  

Microsoft Academic Search

The determination of the risk from flooding that shorefront communities face is an important component of coastal management that has not been resolved successfully. Wave runup offers one way of quantifying the risk of coastal flooding that results from overtopping by storm waves. The calculation of runup probabilities uses wave frequency analysis and an average beach\\/dune profile for a given

Paul A. Garès

1990-01-01

296

SPATIAL VARIATIONS IN SUSPENDED SEDIMENT TRANSPORT OVER DUNES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The magnitude of the lateral variations in the concentration of suspended sediment over dunes in an alluvial sand-bed channel are poorly known. Characterizing the lateral distributions of suspended sediment is important for understanding its causes and for accurate measurement of the rate of sedim...

297

Coastal sand dune stabilization in the Pacific Northwest  

Microsoft Academic Search

Coastal dunes are stabilized in three stages: (1) The initial stage uses sand-stilling grasses established vegetatively. For this purpose, European beachgrass, Ammophila arenaria (L.) Link., is most used, followed by American beachgrass, A. breviligulata Fern., or American dunegrass, Elymus mollis Trin. Large solid plantings must be made with the spacing and number of plants per hill adjusted to the site

J. L. Schwendiman

1977-01-01

298

Vetiver System for Sand Dune Stabilization A Vietnamese Experience  

Microsoft Academic Search

Sand dunes occupy more than 70,000 ha along the coast of Central Vietnam, being the sources of such natural disasters as sand storm, sand flow\\/flash flood etc., that eat either slowly or catastrophically villages and fields. This has been surveyed by a team of geologists from the Research Institute of Geology and Mineral Resources (RIGMR), who also looked for remedial

299

Dunes, turbulent eddies, and interfacial exchange with permeable sediments  

Microsoft Academic Search

Interfaces between a water column and underlying porous media are ubiquitous in nature. Turbulent flow over an irregular interface separating a water column and underlying porous media drives advective-fluid exchange between the two domains. We investigate the dynamics of this coupled system for unidirectional flow in the water column and a triangular interface modeled on dunes. Numerical simulations solve the

M. Bayani Cardenas; John L. Wilson

2007-01-01

300

The timing of EV recharging and its effect on utilities  

SciTech Connect

Electric vehicles (EV's) represent an important future load on the electric utility system which, if properly managed, could increase power plant utilization and reduce the average cost of generating electricity. A future EV population of 7.5 million is addressed, together with its characteristics, vehicle use, consequent recharging loads, and the impact of EV's on electric utilities in terms of the generation of electric power, fuel use, and costs. The impact on utilities will depend in part on when the vehicles are recharged. If the price of electricity is uniform throughout the day, recharging is likely to begin when vehicles are parked at home. Most of the recharging would then occur during late afternoon and early evening hours when other demands for electricity are high. In the year 2000, peak electricity demand would increase by 5700 MW, and oil- and gas-fired power plants would generate 39 percent of the recharge power. Marginal generating costs would average 7.6 cents/kWh in 1982 dollars. If electricity were priced by time of day, recharging could shift to late night hours when the other demands for electricity are low. The peak demand would increase by only 400 MW; 27 percent of the power would come from oil and gas, and marginal generating costs would average only 5.1 cents/kWh, some 25 percent less than the marginal cost of the system load without EV's. The fuels to recharge EV's were found to vary from one region of the country to the next. Utilities in the northeast would use the most oil and gas for recharging (more than 75 percent), while those in the central part of the country would use the least.

Collins, M.M.; Mader, G.H.

1983-02-01

301

Electrochemical behavior of hydrated molybdenum oxides in rechargeable lithium batteries  

Microsoft Academic Search

Oxide-hydrates of molybdenum (OHM) are investigated as 3-volt cathode materials for rechargeable lithium batteries. These\\u000a materials with different water content showed a much better performance than that of MoO3 as cathode of the rechargeable lithium battery. We report the electrochemical characteristics of Li\\/\\/OHM batteries using\\u000a the oxides and oxide-hydrates of molybdenum which were synthesized from molybdic acid. The oxide has

B. Yebka; C. Julien; G. A. Nazri

1999-01-01

302

Estimating Regional Groundwater Recharge Using a Hydrological Budget Method  

Microsoft Academic Search

Estimating groundwater recharge is a key component in determining the sustainable yield of groundwater resources in arid and\\u000a semi-arid areas such as southern California. Estimating groundwater recharge on a regional scale requires developing a water\\u000a budget that incorporates data on boundary conditions, aquifer properties, groundwater levels, and groundwater production.\\u000a The hydrological budget method proposed herein is simple, cost-effective, and easy

Fakhri Manghi; Behrooz Mortazavi; Christie Crother; Moshrik R. Hamdi

2009-01-01

303

Ground water recharge and flow characterization using multiple isotopes.  

PubMed

Stable isotopes of delta(18)O, delta(2)H, and (13)C, radiogenic isotopes of (14)C and (3)H, and ground water chemical compositions were used to distinguish ground water, recharge areas, and possible recharge processes in an arid zone, fault-bounded alluvial aquifer. Recharge mainly occurs through exposed stream channel beds as opposed to subsurface inflow along mountain fronts. This recharge distribution pattern may also occur in other fault-bounded aquifers, with important implications for conceptualization of ground water flow systems, development of ground water models, and ground water resource management. Ground water along the mountain front near the basin margins contains low delta(18)O, (14)C (percent modern carbon [pmC]), and (3)H (tritium units [TU]), suggesting older recharge. In addition, water levels lie at greater depths, and basin-bounding faults that locally act as a flow barrier may further reduce subsurface inflow into the aquifer along the mountain front. Chemical differences in ground water composition, attributed to varying aquifer mineralogy and recharge processes, further discriminate the basin-margin and the basin-center water. Direct recharge through the indurated sandstones and mudstones in the basin center is minimal. Modern recharge in the aquifer is mainly through the broad, exposed stream channel beds containing coarse sand and gravel where ground water contains higher delta(18)O, (14)C (pmC), and (3)H (TU). Spatial differences in delta(18)O, (14)C (pmC), and (3)H (TU) and occurrences of extensive mudstones in the basin center suggest sluggish ground water movement, including local compartmentalization of the flow system. PMID:18384592

Chowdhury, Ali H; Uliana, Matthew; Wade, Shirley

2008-04-02

304

Volcaniclastic dunes from the 2006 deposits of Tungurahua volcano, Ecuador  

NASA Astrophysics Data System (ADS)

Tungurahua volcano has been in eruption intermittently since 1999 and showed peaks in activity in 2006, 2008, and 2010. This study focuses on the deposits from August 2006 small volume pyroclastic density currents (PDC). These deposits show two different facies types, due to interaction with topography. A poorly sorted coarse unit of blocks and ash is mainly found within valleys that had confined the PDCs and was driven by gravity, probably traveling partially fluidized. A stratified, coarse depleted, ash unit, up to 5 meters in thickness, is usually found outside the valleys on outer sides of curves, or at changes of topography. The difference in emplacement position shows that inertial forces were more important than gravity forces for the ash unit. Deposition of the coarse depleted unit is caused by a hydraulic jump. The main characteristic feature of the ash unit is the presence of fields of dunes on its surface. Dunes (also referred as sand waves) produced in PDCs have been reported in various places and several types can be characterized. Their length ranges from 1 to several tens of meters for a length/ height ratio (L/H) that is usually in the range of 10 to 20. Grain size varies from fine ash to lapilli sizes. Most volcanic dunes are interpreted as deposited by supercritical flow (antidunes) because of the occurrence of upstream side aggradation and the low angle slopes. However, dunes were sometimes related with high depositional rates because of the occurrence of a climbing structure (Taal volcano). Tungurahua type dunes are atypical. They are much steeper with L/H=5, for length ranging from 1 to 8 meters. Interestingly, the steepest slope is usually the one facing to the vent. The largest dunes have linear transverse shapes, smaller ones also show lunate shapes. Internally, cross stratification is well defined by layers of fine ash alternating with layers of coarse ash. The structure exhibits different patterns, showing aggradation on the downslope, on the upslope, or both sides (climbing dunes). Usually, Tungurahua dunes don't show migration of the entire structure as commonly observed in fluvial or aeolian conditions. Here, stoss side reworking of deposited material by the flow is minor, only the position of the crest is migrating. Two scenarios are possible for the observed features: 1) A very high deposition rate in low wind conditions, leading to climbing structures (high deposition) and steep slopes (low wind). These conditions are in agreement with the presence of a hydraulic jump. 2) The occurrence of a large scale backflow (flowing upslope) due to the detachment of the entire flow from the ground in some places. This latter interpretation explains why the upslope side (thus lee side!) is steeper, the upward crest migration of climbing dunes, and the low L/H ratio, but is more difficult to imagine. From our data set we infer that in both cases the dunes at Tungurahua volcano result from highly depositional conditions but are not antidunes. Experimental and simulational approaches to understanding the deposition of these structures are being developed.

Douillet, G.; Hanson, J. B.; Goldstein, F.; Kueppers, U.; Tsang-Hin-Sun; Bustillos, J.; Robin, C.; Dingwell, D. B.

2010-12-01

305

Recharge signal identification based on groundwater level observations.  

PubMed

This study applied a method of the rotated empirical orthogonal functions to directly decompose the space-time groundwater level variations and determine the potential recharge zones by investigating the correlation between the identified groundwater signals and the observed local rainfall records. The approach is used to analyze the spatiotemporal process of piezometric heads estimated by Bayesian maximum entropy method from monthly observations of 45 wells in 1999-2007 located in the Pingtung Plain of Taiwan. From the results, the primary potential recharge area is located at the proximal fan areas where the recharge process accounts for 88% of the spatiotemporal variations of piezometric heads in the study area. The decomposition of groundwater levels associated with rainfall can provide information on the recharge process since rainfall is an important contributor to groundwater recharge in semi-arid regions. Correlation analysis shows that the identified recharge closely associates with the temporal variation of the local precipitation with a delay of 1-2 months in the study area. PMID:22016042

Yu, Hwa-Lung; Chu, Hone-Jay

2011-10-21

306

Estimating aquifer channel recharge using optical data interpretation.  

PubMed

Recharge through intermittent and ephemeral stream channels is believed to be a primary aquifer recharge process in arid and semiarid environments. The intermittent nature of precipitation and flow events in these channels, and their often remote locations, makes direct flow and loss measurements difficult and expensive. Airborne and satellite optical images were interpreted to evaluate aquifer recharge due to stream losses on the Frio River in south-central Texas. Losses in the Frio River are believed to be a major contributor of recharge to the Edwards Aquifer. The results of this work indicate that interpretation of readily available remote sensing optical images can offer important insights into the spatial distribution of aquifer recharge from losing streams. In cases where upstream gauging data are available, simple visual analysis of the length of the flowing reach downstream from the gauging station can be used to estimate channel losses. In the case of the Frio River, the rate of channel loss estimated from the length of the flowing reach at low flows was about half of the loss rate calculated from in-stream gain-loss measurements. Analysis based on water-surface width and channel slope indicated that losses were mainly in a reach downstream of the mapped recharge zone. The analysis based on water-surface width, however, did not indicate that this method could yield accurate estimates of actual flow in pool and riffle streams, such as the Frio River and similar rivers draining the Edwards Plateau. PMID:21434908

Walter, Gary R; Necsoiu, Marius; McGinnis, Ronald

2011-03-24

307

Pressure Fluctuation Caused by Dune Structures in Hydraulic Solid Transport Pipe Flow  

NASA Astrophysics Data System (ADS)

This paper presents an experimental investigation on flow pressure fluctuation caused by dune formation during hydraulic solid transportation in horizontal pipelines. Digital photography was employed to study the morphologic characteristics of sand bed transportation with corresponding time based pressure measurement obtained using a pressure transducer. Combined, these experimental results characterized the interaction between dune formation and flow pressure fluctuation. With dune structures formed, significant pressure fluctuation was detected. These measurements combined with previous studies on dune flow field contribute to the fundamental insights into the physics of dune mode hydraulic solid transport flow in a closed conduit.

Wang, L.; Goharzadeh, A.; Rodgers, P.

2011-09-01

308

Evidence for community structure and habitat partitioning in coastal dune stiletto flies at the Guadalupe-Nipomo dunes system, California  

Microsoft Academic Search

This study provides empirical evidence for habitat selection by North American species of stiletto flies (Diptera: Therevidae), based on local distributions of adults and immatures, and the first hypothesis of community assemblages proposed for a stiletto fly community. Sites at three localities within the Guadalupe-Nipomo dune system were sampled for stiletto flies in 1997 and 2001 by sifting sand, malaise

Kevin C. Holston

2005-01-01

309

Recharge to the North Richland well field  

SciTech Connect

The investigation was based on a preliminary ground-water flow model of the 1100 Area. Because few local data were available for this effort, an existing regional ground-water flow model of the Hanford Site was applied, which is based on the Variable Thickness Transient (VTT) ground-water flow code (Kipp et al., 1976). A submodel of the Hanford Site model was developed based on the VTT code. An independent model consisting of a simple representation of the local conditions in the vicinity of the North Richland well field was also used in the investigation. This model, based on the MODFLOW code (McDonald and Harbaugh, 1984), was used in a series of transient simulations to examine dynamic aspects of the well field/recharge basin. Results from this simple model also provide an independent, qualitative check of results produced with the 1100 Area model based on the VTT code. This report summarizes the 1100 Area modeling investigation, including the approach used to generate results for the regional and 1100 Area VTT models, the approach used in the transient MODFLOW model, results from some initial steady-state and transient simulations with the submodel and the MODFLOW models, and resulting conclusions and recommendations. Because local data were lacking to develop and calibrate the models, the investigation described in this report can best be described as a ''sensitivity analysis'' of ground-water flow in the 1100 Area. 4 refs., 10 figs., 2 tabs.

Law, A.G.

1989-07-01

310

Advanced rechargeable sodium batteries with novel cathodes  

NASA Astrophysics Data System (ADS)

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg were realized in practical batteries. Other technological advantages include its chemical simplicity, absence of self-discharge, and long cycle life possibility. More recently, other high temperature sodium batteries have come into the spotlight. These systems can be described as follow: Na/Beta Double Prime-Al2O3/NaAlCl4/Metal Dichloride Sodium/metal dichloride systems are colloquially known as the zebra system and are currently being developed for traction and load leveling applications. The sodium-metal dichloride systems appear to offer many of the same advantages of the Na/S system, especially in terms of energy density and chemical simplicity. The metal dichloride systems offer increased safety and good resistance to overcharge and operate over a wide range of temperatures from 150 to 400 C with less corrosion problems.

Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1989-12-01

311

Characterization of AA size lithium rechargeable cells  

NASA Astrophysics Data System (ADS)

Testing of AA size rechargeable cells for underwater vehicle and other naval applications is complete for AT&T's lithium/niobium triselenide (Li/NbSe3) and Moli Energy's lithium/molybdenum disulfide (Li/MoS2) and in progress on Moli Energy's lithium/manganese dioxide (Li/MnO2) and W. R. Grace's lithium/titanium disulfide (Li/TiS2). Cell cycling was performed at various discharge rates, temperatures, and depths of discharge. At 25 C and 1 mA/cm2 (roughly the C/4 rate), delivered energy densities were about 40 Wh/lb for NbSe3, TiS2, and MnO2 and 22 Wh/lb for MoS2. Under the same conditions, nickel/cadmium (Ni/Cd) cells deliver only 10 Wh/lb. However Ni/Cd cycles much longer and the lithium cells are far more vulnerable than Ni/Cd to performance loss in low temperature, high discharge rate cycling. The NbSe3 data and the (limited) TiS2 data indicate that these cells tend to accept excessive charge which is often associated with lithium dendrite shorting and considered potentially hazardous. At 1 mA/cm2 and 25 C, discharge plateaus ranged from 2.9 V for MnO2 to 1.8 V for MoS2.

Murphy, T. C.; Cason-Smith, D. M.; James, S. D.; Smith, P. H.

312

Rechargeable lithiated thin film intercalation electrode battery  

SciTech Connect

This patent describes a rechargeable lithium battery, it comprises: an electrode providing a source of lithium ions, an electrolyte, and a counter-electrode consisting essentially of a lithiated transition metal oxide intercalation compound selected from the class consisting of LiMn{sub 2}O{sub 4}, LiCoO{sub 2} and LiNiO{sub 2} characterized in that the counter-electrode consists essentially of a thin film of the intercalation compound prepared by situating a suitable coating substrate in an air-tight enclosure with a supply of the lithiated metal oxide; establishing within the enclosure a low pressure, carbon-free atmosphere; vaporizing at least a portion of the metal oxide; condensing the metal oxide vapor on a surface of the substrate in a coating having a thickness in the range of about 1 to 5 micrometers; and heating the coating within the atmosphere at a temperature and for a time sufficient to convert the coating to crystallites of the metal oxide having a grain size in the range of about 0.05 to 0.1 micrometer.

Shokoohi, F.K.; Tarascon, J.M.

1992-05-05

313

Electrolyte for laminated polymer lithium rechargeable battery  

NASA Astrophysics Data System (ADS)

Proposed thin film battery is comprised of a polymer-lithium ion cell material with barrier-layer packaging and mechanical reinforcing layers. A semi-solid/ solid electrolyte and a mesoporous polymer separator are sandwiched in between of anode and cathode. A composite film with a carbon nanotube (CNT) network serves as the anode and a mesoporous transitional metal oxide LixCoO2 as the cathode, where porous metal sheets serve as the current collector. The CNT network fabrics have high in-plane tensile strength. LiCoO2 is used as the cathode, because the Co atoms do not migrate to Li layers, so that cathode does not generate flammable gases during charging that create safety problems. Merit of this study is using the porous metal sheet, which is flexible, lightweight, low electric resistance, high strength and strong stability in alkaline solution. This paper presented development of electrolyte for laminated polymer lithium rechargeable battery. Two-type electrolytes, semi-solid and solid, were attempted; high ionic conductivity of Li ion electrolytes was achieved.

Xu, Chunye; Ma, Chao; Taya, Minoru

2008-05-01

314

Aeolian Dunes as Evidence for Explosive Volcanism in the Tharsis Region of Mars  

NASA Astrophysics Data System (ADS)

Two transverse dune fields occur among Late Amazonian volcanic and aeolian landforms in southwestern Tharsis, Mars. The first is located ˜70 km northwest of Biblis Patera, around 5°N, 125°W. The second is located about 500 km northwest of Arsia Mons, at 2°S, 130°W. The latter is the largest dune field thus far documented to occur in the equatorial latitudes of Mars. Unlike other dunes on the planet, both dune fields in Tharsis have low thermal inertias (<2.7 × 10 -3cal cm -2sec -0.5K -1) and high albedos (˜0.26) that are indistinct from their surrounding terrain. Both dune fields have superposed features, such as impact craters, lava flows, smooth-surfaced units, and bright wind streaks. The dune fields therefore appear to be inactive and mantled by fine-grained material (i.e., particles <60 ?m). To form, aeolian dunes require a supply of sand. On Earth, most dune sands are supplied by fluvial and littoral processes, but this is not the case in Tharsis on Mars. Because they are superposed on a Late Amazonian surface, the climate is assumed to have been hyper-arid throughout the time that the dunes have existed. Under these conditions, the only plausible source for quantities of sediment sufficient to form transverse dune fields is explosive volcanism. Therefore, the two dune fields in Tharsis are evidence that explosive volcanism has occurred in this region in the Late Amazonian Epoch.

Edgett, Kenneth S.

1997-11-01

315

Sticky dunes in a wet desert: Formation, stabilisation and modification of the Australian desert dunefields  

NASA Astrophysics Data System (ADS)

Independent dating evidence and dune morphology indicate great stability of the Australian dunefields. Most dunefields have seen only minor superficial modification since they were formed, up to 1 million years ago, despite quite large changes in climate conditions. This stability may be partly due to the relatively dense vegetation cover on Australian dunes under the marginally arid climate. But new studies, supported by many older observations, suggest that 'sticky' dunes (where sand grains are bonded or cemented) may form under a broader range of wind climates than widely thought and have greater resistance to reworking. New mapping of the Australian continental dunefields from satellite imagery shows a previously unrecognised diversity of dune morphologies. Dune orientation, continuity, connectedness, crest planform, crest sharpness, spacing and setting all show patterns of variation over the continent. These are consistent with the overall low sand supply and variable wind climate that contribute to the dominance of longitudinal dunes but also with only superficial modification of the dunes after their initial formation. The longevity of the dunes is likely also partly due to the stabilisation of dune sand by pedogenesis: the bonding of sand by pedogenic calcium carbonate, gypsum, silica and translocated clays. The extremely low mobility of the sand dunes has led to preservation of dunes of great age, with stacked accretionary units and multiple palaeosols.

Hesse, Paul

2011-11-01

316

Why do active and stabilized dunes coexist under the same climatic conditions?  

PubMed

Sand dunes can be active (mobile) or stable, mainly as a function of vegetation cover and wind power. However, there exists as yet unexplained evidence for the coexistence of bare mobile dunes and vegetated stabilized dunes under the same climatic conditions. We propose a model for dune vegetation cover driven by wind power that exhibits bistabilty and hysteresis with respect to the wind power. For intermediate wind power, mobile and stabilized dunes can coexist, whereas for low (or high) wind power they can be fixed (or mobile). Climatic change or human intervention can turn active dunes into stable ones and vice versa; our model predicts that prolonged droughts with stronger winds can result in dune reactivation. PMID:17501612

Yizhaq, Hezi; Ashkenazy, Yosef; Tsoar, Haim

2007-05-02

317

Wind deposition of mud aggregates and their role in development of lamellae in the Fair Oaks Dunes, Indiana  

Microsoft Academic Search

Three parabolic dunes from the Fair Oaks Dune field in northern Indiana were excavated, in order to study the properties and genesis of lamellae. Reddish lamellae with sharp upper boundaries and diffuse lower boundaries are intercalated with yellowish sand layers within the upper 3–5 m of each dune. The thicknesses of the lamellae decrease from >2 cm in the east (Winamac dune)

Zoran Kilibarda; Erin Argyilan; Joe Blockland

2008-01-01

318

Laboratory Analyses Of Basaltic Dunes In The Ka'u Desert Of Hawaii And Implications For Understanding Dark Dunes On Mars  

NASA Astrophysics Data System (ADS)

Dark dunes are the dominant aeolian bedforms on Mars and consist of ancient volcanic ashes and reworked basaltic lavas. Basaltic dunes are rare on Earth and only occur in limited areas, such Hawaii. Because the Hawaiian dunes are composed of reworked basaltic sediments transported by eolian processes, they are a promising subject matter of analogy studies. Samples of dark dune sands, ash, and tephra collected in Hawaii's Ka'u Desert were collected during field trips in summer 2009 and 2010. They were analyzed by a variety of laboratory methods, including spectral, microscope, and microprobe investigations, in order examine their detailed mineralogical composition and constitution. We then compared the results to the eolian dunes on Mars. Sand samples were collected from three different dark dunes in Ka'u Desert: a large, vegetated, parabolic dune, a falling dune, and a large climbing dune. Tephra from the phreatic eruption that began in March 2008 was collected over a two year period using sample collectors placed at different locations downwind of Kilauea caldera. Analyses of these samples allow us to determining the initial composition, grain shape, and grain size of probable source materials. The visible and near-infrared reflectance spectra of the samples were acquired for the 0.5 to 2.5µm range. The overall spectral shape of the dune sand samples indicates a mineralogical correlation between Martian and terrestrial dune sands indicating a similar volcanic origin of the sediments. The spectra of the Hawaiian samples reveal some aqueous alteration, which is probably related to hydrated amorphous silica. Initial microscope and microprobe analyses reveal a high amount of volcanic glass and rock fragments in the samples, followed by olivine, feldspars, and pyroxene. Vitric particles that dominate the majority of the dune samples indicate in situ material accumulation following larger phreatic eruptions. The top coarse-grained layer of the climbing dune comprises a higher amount of rock fragments, indicating that these sands originate from reworked lava and were deposited in a subsequent dune formation phase (see also Craddock et al., this conference). We will present the comparison of Martian, terrestrial and library spectra, determine grain shape and grain size, and propose possible sediment sources, transport mechanisms, and development of the dune material.

Tirsch, D.; Craddock, R. A.; Nanson, G.; Tooth, S.; Langhans, M.

2010-12-01

319

Fate of human viruses in groundwater recharge systems  

SciTech Connect

The overall objective of this research program was to determine the ability of a well-managed tertiary effluent-recharge system to return virologically acceptable water to the groundwater aquifer. The study assessed the quality of waters renovated by indigenous recharge operations and investigated a number of virus-soil interrelationships. The elucidation of the interactions led to the establishment of basin operating criteria for optimizing virus removal. Raw influents, chlorinated tertiary effluents, and renovated wastewater from the aquifer directly beneath a uniquely designed recharge test basin were assayed on a weekly basis for the presence of human enteroviruses and coliform bacteria. High concentrations of viruses were routinely isolated from influents but were isolated only on four occasions from tertiary-treated sewage effluents. In spite of the high quality effluent being recharged, viruses were isolated from the groundwater observation well, indicating their ability to penetrate the unsaturated zone. Results of poliovirus seeding experiments carried out in the test basin clearly indicated the need to operate recharge basins at low (e.g. 1 cm/h) infiltration rates in areas having soil types similar to those found at the study site. The method selected for reducing the test basin infiltration rate involved clogging the basin surface with settled organic material from highly turbid effluent. Alternative methods for slowing infiltration rates are discussed in the text.

Vaughn, J.M.; Landry, E.F.

1980-03-01

320

Transcutaneous battery recharging by volume conduction and its circuit modeling.  

PubMed

Many implantable devices require large capacity batteries implanted in the body. Transcutaneous battery recharging can effectively maintain the longevity of these implants. Based on this consideration we have developed a transcutaneous battery recharging circuit unit which takes advantages of skin volume conduction. This unit is able to pass 2.8 mA from the outside to the inside of pig skin with a current transmitting efficiency of 27%. Theoretical analysis and experiments have validated that this battery recharging technology is an effective approach. In this research we have constructed an x-type equivalent circuit model of skin volume conduction for battery recharging. The parameters of the x-type equivalent circuit can be easily measured and used to evaluate the battery charging system characteristics, such as the rechargeable prerequisite and the current transmitting efficiency limitation. We have analyzed the transcutaneous current transmitting efficiency by applying the x-type equivalent circuit model and discussed approaches for enhancing current transmitting efficiency. PMID:17945991

Tang, Zhide; Sclabassi, Robert J; Sun, Caixin; Hackworth, Steven A; Zhao, Jun; Cui, Xinyan T; Sun, Mingui

2006-01-01

321

Delineating volcanic aquifer recharge areas using geochemical and isotopic tools  

NASA Astrophysics Data System (ADS)

Relative recharge areas are evaluated using geochemical and isotopic tools, and inverse modeling. Geochemistry and water quality in springs discharging from a volcanic aquifer system in Guatemala are related to relative recharge area elevations and land use. Plagioclase feldspar and olivine react with volcanically derived CO2 to produce Ca-montmorillonite, chalcedony and goethite in the groundwater. Alkalinity, Mg, Ca, Na, and SiO2(aq) are produced, along with minor increases in Cl and SO4 concentrations. Variations in groundwater ?D and ?18O values are attributed to recharge elevation and used in concert with geochemical evolution to distinguish local, intermediate, and regional flow systems. Springs with geochemically inferred short flow paths provided useful proxies to estimate an isotopic gradient for precipitation (-0.67 ?18O/100 m). No correlation between spring discharge and relative flow-path length or interpreted recharge elevation was observed. The conceptual model was consistent with evidence of anthropogenic impacts (sewage and manure) in springs recharged in the lower watershed where livestock and humans reside. Spring sampling is a low-budget approach that can be used to develop a useful conceptual model of the relative scale of groundwater flow (and appropriate watershed protection areas), particularly in volcanic terrain where wells and boreholes are scarce.

Mulligan, Brendan M.; Ryan, M. Cathryn; Cámbara, Tomás Padilla

2011-11-01

322

Debris-flow benches: Dune-contact deposits record paleo-sand dune positions in north Panamint Valley, Inyo County, California  

SciTech Connect

Debris flows debouching onto the alluvial fan at the north end of Panamint Valley, California, have been episodically impounded behind sand dunes, resulting in boulder-strewn, nearly flat topped deposits in irregular basins upslope of the dune, whose upper surface is higher than the adjacent fan surface. Upslope migration of the dune field over and beyond these deposits eventually leaves them as debris-flow benches rising above the general fan surface. These features are therefore dune-contact forms, analogous to ice-contact forms such as kame terraces, in that both involve deposition against ephemeral barriers. Benches punctuate the alluvial-fan surface for 5 km downfan from the modern dune field. Clast seismic velocities of boulders on these benches indicate that bench ages increase monotonically with distance from the present dunes, implying that the dune field has migrated up the fan. Because the oldest bench is below the altitude of the highest pluvial lake shoreline in Panamint Valley (Gale Stage, ca. 50 ka) and slightly above the latest lakeshore (I Stage, ca. 14 ka), it seems likely that the dunes originated near the shore of the latest lake and have moved upfan at an average rate of 0.8 m/yr.

Anderson, S.P. (Univ., of California, Berkeley (USA)); Anderson, R.S. (Univ. of California, Santa Cruz (USA))

1990-06-01

323

Debris-flow benches: Dune-contact deposits record paleo-sand dune positions in north Panamint Valley, Inyo County, California  

NASA Astrophysics Data System (ADS)

Debris flows debouching onto the alluvial fan at the north end of Panamint Valley, California, have been episodically impounded behind sand dunes, resulting in boulder-strewn, nearly flat topped deposits in irregular basins upslope of the dunes, whose upper surface is higher than the adjacent fan surface. Upslope migration of the dune field over and beyond these deposits eventually leaves them as debris-flow benches rising above the general fan surface. These features are therefore dune-contact forms, analogous to ice-contact forms such as kame terraces, in that both involve deposition against ephemeral barriers. Benches punctuate the alluvial-fan surface for 5 km downfan from the modern dune field. Clast seismic velocities of boulders on these benches indicate that bench ages increase monotonically with distance from the present dunes, implying that the dune field has migrated up the fan. Because the oldest bench is below the altitude of the highest pluvial lake shoreline in Panamint Valley (Gale Stage, ca. 50 ka) and slightly above the latest lakeshore (I Stage, ca. 14 ka), it seems likely that the dunes originated near the shore of the latest lake and have moved upfan at an average rate of 0.8 m/yr.

Prestrud Anderson, Suzanne; Anderson, Robert S.

1990-06-01

324

Dunes and microdunes on Venus: Why were so few found in the Magellan data?  

NASA Astrophysics Data System (ADS)

A search through cycle 1, 2, and 3 Magellan radar data covering 98% of the surface of Venus revealed very few dunes. Only two possible dune fields and several areas that may contain microdunes smaller than the resolution of the images (75 m) were identified. The Aglaonice dune field was identified in the cycle 1 images by the specular returns characteristic of dune faces oriented perpendicular to the radar illumination. Cycle 1 and 2 data of the Fortuna-Meshkenet dune field indicate that there has been no noticeable movement of the dunes over an 8-month period. The dunes, which are oriented both parallel and perpendicular to the radar illumination, appear to be dark features on a brighter substrate. Bright and dark patches that were visible in either cycle 1 or 2 data, but not both, allowed identification of several regions in the southern part of Venus that may contain microdunes. The microdunes are associated with several parabolic crater deposits in the region and are probably similar to those formed in wind tunnel experiments under Venus-like conditions. Bragg scattering and/or subpixel relfections from the near-normal face on asymmetric microdunes may account for these bright and dark patches. Look-angle effects and the lack of sufficient sand-size particles seem to be most likely reasons so few dunes were identified in Magellan data. Insufficient wind speeds, thinness of sand cover, and difficulty in identifying isolated dunes may also be contributors to the scarcity of dunes.

Weitz, Catherine M.; Plaut, Jeffrey J.; Greeley, Ronald; Saunders, R. Steven

1994-11-01

325

Soil Processes and Salt Dynamics in Dune Soils  

Microsoft Academic Search

In Chapter 5 (this volume), we described the soil pattern and characteristics of the sand dune ecosystem of Nizzana. In the\\u000a following, we will reconstruct the formation of the main soils, their weathering and brownification, their aggregation and\\u000a crust formation, their humus accumulation and carbonate accumulation being some of the main soil processes. However, our special\\u000a interest will be on

P. Felix-Henningsen; B. Rummel; H.-P. Blume

326

Comment on "Minimal size of a barchan dune".  

PubMed

It is now an accepted fact that the size at which dunes form from a flat sand bed as well as their "minimal size" scales on the flux saturation length. This length is by definition the relaxation length of the slowest mode toward equilibrium transport. The model presented by Parteli, Durán, and Herrmann [Phys. Rev. E 75, 011301 (2007)] predicts that the saturation length decreases to zero as the inverse of the wind shear stress far from the threshold. We first show that their model is not self-consistent: even under large wind, the relaxation rate is limited by grain inertia and thus cannot decrease to zero. A key argument presented by these authors comes from the discussion of the typical dune wavelength on Mars (650 m) on the basis of which they refute the scaling of the dune size with the drag length evidenced by Claudin and Andreotti [Earth Planet. Sci. Lett. 252, 30 (2006)]. They instead propose that Martian dunes, composed of large grains (500 microm), were formed in the past under very strong winds. We emphasize that this saltating grain size, estimated from thermal diffusion measurements, is far from straightforward. Moreover, the microscopic photographs taken by the rovers on Martian Aeolian bedforms show a grain size of 87+/-25 microm together with hematite spherules at millimeter scale. As those so-called "blueberries" cannot be entrained more frequently than a few hours per century, we conclude that the saltating grains on Mars are the small ones, which gives a second strong argument against the model of Parteli. PMID:18233886

Andreotti, B; Claudin, P

2007-12-21

327

Seasonality of mycorrhizae in coastal sand dunes of Baja California  

Microsoft Academic Search

Populations of arbuscular mycorrhizal fungi were estimated from spores associated with seven plant species in coastal dunes\\u000a at El Socorro, near Ensenada, Baja California, during six months in 1992. The seasonal patterns of percent root colonization\\u000a were also described in the same species during the wet season (January–March) and the dry season (April–July). Comparisons\\u000a were made between the pioneer species

Concepción Sigüenza; Ileana Espejel; Edith B. Allen

1996-01-01

328

Hippophae rhamnoides on a coastal dune system: a thorny issue?  

Microsoft Academic Search

The study mapped the spread of the invasive non-native shrub, Hippophae rhamnoides, on a coastal dune system in South Wales. H. rhamnoides colonies spread across the system, covering around 60.9 ha in 1996 compared to 2.4 ha in 1957. Clearance activities have\\u000a since decreased the total to around 23 ha. The effects of this expansion on ground flora were assessed through comparison\\u000a of

Elen Gwenllian Richards; Helene Burningham

2011-01-01

329

Runoff and Erosion Processes Within a Dune System  

Microsoft Academic Search

The occurrence of surface runoff processes is often regarded by geomorphologists or hydrologists as irrelevant within sandy\\u000a areas and dune systems, due to the very high infiltration rates of sand. The presumed lack of runoff processes has been mentioned\\u000a several times in the case of the northwestern Negev sand field (Hillel and Tadmor 1962; Tsoar and Zohar 1985; Tsoar and

G. J. Kidron; A. Yair

330

Détection et caractérisation optiques d'une nanoparticule métallique isolée  

NASA Astrophysics Data System (ADS)

La détection optique d'une nanoparticule métallique unique par une nouvelle technique de microscopie par modulation spatiale est décrite. Dans le cas d'un nano-objet de métal noble, la mesure quantitative de son spectre d'absorption au voisinage de la résonance plasmon de surface et sa comparaison précise à un modèle théorique permettent une identification optique complète de l'objet étudié: taille, forme et orientation sur la surface sont déterminées.

Del Fatti, N.; Muskens, O.; Vallée, F.; Huntzinger, J. R.; Billaud, P.; Broyer, M.

2006-10-01

331

Predicting flooding probability for beach\\/dune systems  

Microsoft Academic Search

The determination of the risk from flooding that shorefront communities face is an important component of coastal management\\u000a that has not been resolved successfully. Wave runup offers one way of quantifying the risk of coastal flooding that results\\u000a from overtopping by storm waves. The calculation of runup probabilities uses wave frequency analysis and an average beach\\/dune\\u000a profile for a given

Paul A. Garès

1990-01-01

332

Association d'une cytost?aton?crose n?onatale, d'une hypertriglyc?ridemie et d'une hypercalc?mie: ? propos d'une observation  

PubMed Central

La cytostéatonécrose du nouveau-né est une hypodermite aigue qui apparaît dans les premières semaines de vie. Nous rapportons les caractéristiques cliniques et histologiques d’une cytostéatonécrose chez un nourrisson âgé de trois semaines, admis pour des lésions cutanées à type de placards sous-cutanées dures, localisées sur le dos. Le nouveau-né a développé une hypercalcémie et une hypertriglycéridemie d’évolution favorable sous traitement symptomatique de même que les lésions cutanées qui ont disparu en quelques semaines.

Abilkassem, Rachid; Dini, Nezha; Oukabli, Mohamed; Kmari, Mohamed; Agadr, Aomar

2012-01-01

333

Coastal sand dune stabilization in the Pacific Northwest  

Microsoft Academic Search

Coastal dunes are stabilized in three stages: (1) The initial stage uses sand-stilling grasses established vegetatively. For this purpose, European beachgrass,Ammophila arenaria (L.) Link., is most used, followed by American beachgrass,A. breviligulata Fern., or American dunegrass,Elymus mollis Trin. Large solid plantings must be made with the spacing and number of plants per hill adjusted to the site conditions. Plantings, using

J. L. Schwendiman

1977-01-01

334

Interdisciplinary Research Produces Results in the Understanding of Planetary Dunes  

NASA Astrophysics Data System (ADS)

Second International Planetary Dunes Workshop: Planetary Analogs—Integrating Models, Remote Sensing, and Field Data; Alamosa, Colorado, 18-21 May 2010; Dunes and other eolian bed forms are prominent on several planetary bodies in our solar system. Despite 4 decades of study, many questions remain regarding the composition, age, and origins of these features, as well as the climatic conditions under which they formed. Recently acquired data from orbiters and rovers, together with terrestrial analogs and numerical models, are providing new insights into Martian sand dunes, as well as eolian bed forms on other terrestrial planetary bodies (e.g., Titan). As a means of bringing together terrestrial and planetary researchers from diverse backgrounds with the goal of fostering collaborative interdisciplinary research, the U.S. Geological Survey (USGS), the Carl Sagan Center for the Study of Life in the Universe, the Desert Research Institute, and the U.S. National Park Service held a workshop in Colorado. The small group setting facilitated intensive discussion of problems and issues associated with eolian processes on Earth, Mars, and Titan.

Titus, Timothy N.; Hayward, Rosalyn Kay; Bourke, Mary C.

2010-08-01

335

Valles Marineris Dune Fields as Seen From the HiRISE, CTX and THEMIS Cameras  

NASA Astrophysics Data System (ADS)

Dune fields on Mars offer an opportunity to investigate the nature of eroded sediments and their interactions with the atmosphere. We examined 20 dune fields in Valles Marineris (VM) from the Mars Global Digital Dune Database [Hayward et al., 2007] to identify significant trends in composition, thermophysical properties, morphology and origin. Dune fields were examined in terms of: slopes, albedo, dust index, thermal inertia and the corresponding derived particle size. We have used image data from the Mars Reconnaissance Orbiter (MRO) instruments CTX [McEwen et al., 2006] and HiRISE [Malin et al., 2007] to establish geologic context for the dune fields, and in particular, to examine their relationships to neighboring geologic units. In general, VM dune fields display greater topographic relief and closer proximity to their inferred source regions than is typical for dune fields elsewhere on Mars. These dunes have a relatively high TES-derived thermal inertia mean value (394 Jm-2K-1 s-1/2, units hereafter assumed), which corresponds to ~1000 ?m grains [Pelkey et al., 2001] or very coarse sand sizes. In contrast, typical non-VM dunes have a lower thermal inertia value of ~250, corresponding to ~350 ?m grains. To investigate this more closely, high-resolution THEMIS-derived thermal inertia maps were created [Putzig et al., 2004]. CTX and HiRISE visible images revealed that bedrock outcrops are commonly found within dune fields, erroneously elevating the TES thermal inertia values over the ~3x5-km TES footprint. However, even after excluding intra-dune outcrop areas using higher-resolution THEMIS data, several VM dune fields have anomalously high thermal inertia values (>500) compared with non-VM dune fields. It is possible that the high thermal inertia values are indicative of indurated (fossilized) dune surfaces, rather than large individual grain sizes. Coprates Chasma contains a concentration of 6 dune fields both within the main chasm and in depressions to the south. The southern fields are comprised of isolated barchanoid dunes, in close proximity to or atop wall material that has been deposited by mass wasting. In the main chasm, previously unidentified barchans composed of large grain sizes, as inferred from THEMIS thermal inertia, are found in CTX images within spur and gully wall units 2-3 km above the canyon floor. TES spectrum of these dunes indicates a basaltic composition, suggesting that the nearby wall units, also thought to be of a basaltic composition [McEwen et al., 1999], could be the source of the dune sediments. Future MRO observations of this area may resolve whether these dune sediments are locally derived. Ganges Chasma has the highest concentration of dunes in VM, including the largest (~6000 km2) non-polar dune field on Mars. These dunes are found surrounding the sulfate-bearing Ganges Mensa and other layered deposits. In one example, a light-toned yardang containing CRISM-detected hydrated sulfates [Pelkey et al., 2007] has shed fans of fine-grained material, contributing sediment to the area. Dune slipface orientation would suggest a dominant wind direction blowing to the west at the last time of dunes activity. This corresponds with the more recent deposit of lighter-toned material down-wind and atop the dark-toned sand sheets, as observed in HiRISE and THEMIS thermal inertia images. These lighter-toned materials, inferred to be composed of sulfate grains (~350 ?m), form bright ripples which gradually disappear away from the yardang. Whether these sulfates constitute a significant percentage of the dune composition is currently under investigation.

Chojnacki, M.; Moersch, J. E.

2008-12-01

336

Possibility of star (pyramid) dune development in the area of bimodal wind regime  

NASA Astrophysics Data System (ADS)

Star (pyramid) dunes are the largest aeolian landforms. They can occur in three types - simple, complex and compound. Development of this type of dunes is usually connected with multidirectional or complex wind regimes. The aim of this study was to verify a hypothesis that the star dunes can also develop by a bimodal wind regime and by local modifications of nearsurface wind flow directions. Field study was performed on Erg Chebbi, in southern Morocco. Several star and transverse dunes were selected for the study of their shape. The star dunes were analysed concerning their type and position in the dune field. This erg contains all of three types of star dunes together with transverse dunes. The regional wind data show that there are two dominant wind directions - NE (Chergui) and SW (Saheli). To determine the difference in shape of star dunes, we performed topographic surveying by GPS RTK. The results allowed to create 3D models of star dunes. The models were used to determine metric characteristics of star dunes, including area of dune basis, volume, and slope angles. On the basis of 3D models, primary, secondary and, on the compound dunes, tertiary arms were determined. Primary arms on each type of star dunes, as well as crestlines of transverse dunes, have dominant orientation NW-SE, perpendicular to two dominant wind directions. This clearly confirms that star dunes of Erg Chebbi develop by a bimodal wind regime In contrast to primary arms, subsidiary (secondary and tertiary) arms are not connected to general wind regime. The secondary arms of star dunes occur to be differentially developer. There are more subsidiary arms on SW sides in comparison to the E sides of the dunes where inclination of slopes is constant. It can be therefore inferred that sand has been supplied predominantly from SW direction. This is supported by distribution of the dunes on the erg. Most compound star dunes compose a chain along the E margin of the erg. Comparison of compound star dunes located in E and W parts of the erg allow inferring that there must have been differences in supply of the aeolian sand. Eastern slopes of compound star dunes developed in the W part of the erg are inclined 10-15°. This shows that significant delivery of the sand must have occurred also from NE. Eastern slopes of compound star dunes located in the E part of the erg are inclined 20-30°. It can be therefore inferred that they have functioned mainly as lee slopes and the sand was delivery from SW. This proves that location of the dunes within the erg plays a significant role in shaping wind directions responsible for delivery of the sand. Orientation of subsidiary arms does not show any relationship with general wind regime, which leads to conclusion that the subsidiary arms develop due to local diversified regime of nearsurface wind flow. This is governed by barriers such as the star dunes themselves and not by other topographic obstacles.

Biejat, K.

2012-04-01

337

Estimating ground water recharge from topography, hydrogeology, and land cover.  

PubMed

Proper management of ground water resources requires knowledge of the rates and spatial distribution of recharge to aquifers. This information is needed at scales ranging from that of individual communities to regional. This paper presents a methodology to calculate recharge from readily available ground surface information without long-term monitoring. The method is viewed as providing a reasonable, but conservative, first approximation of recharge, which can then be fine-tuned with other methods as time permits. Stream baseflow was measured as a surrogate for recharge in small watersheds in southeastern Wisconsin. It is equated to recharge (R) and then normalized to observed annual precipitation (P). Regression analysis was constrained by requiring that the independent and dependent variables be dimensionally consistent. It shows that R/P is controlled by three dimensionless ratios: (1) infiltrating to overland water flux, (2) vertical to lateral distance water must travel, and (3) percentage of land cover in the natural state. The individual watershed properties that comprise these ratios are now commonly available in GIS data bases. The empirical relationship for predicting R/P developed for the study watersheds is shown to be statistically viable and is then tested outside the study area and against other methods of calculating recharge. The method produces values that agree with baseflow separation from streamflow hydrographs (to within 15% to 20%), ground water budget analysis (4%), well hydrograph analysis (12%), and a distributed-parameter watershed model calibrated to total streamflow (18%). It has also reproduced the temporal variation over 5 yr observed at a well site with an average error < 12%. PMID:15726928

Cherkauer, Douglas S; Ansari, Sajjad A

338

Evaluation of Methods for Estimation of Aquifer Recharge from Precipitation on Semi-Arid Lands.  

National Technical Information Service (NTIS)

Precipitation falling on semi-arid, non-irrigated lands may represent a significant percentage of total aquifer recharge in areas such as the eastern Snake River Plain in southern Idaho. Direct measurement of precipitation recharge is usually not feasible...

G. S. Johnson C. E. Brockway A. Coiner

1985-01-01

339

VIRUS REMOVAL DURING GROUNDWATER RECHARGE: EFFECTS OF INFILTRATION RATE ON ADSORPTION OF POLIOVIRUS TO SOIL  

EPA Science Inventory

Studies were conducted to determine the influence of infiltration rate on poliovirus removal during groundwater recharge with tertiary-treated wastewater effluents. Experiments were conducted at a uniquely designed, field-situated test recharge basin facility through which some 6...

340

SPATIAL SCALING OF SURFACE WATER INFILTRATION AND ITS IMPLICATIONS FOR ESTIMATING GROUNDWATER RECHARGE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The GRAPHIC Project has identified priority research topics related to groundwater recharge, discharge, storage, and water quality. This presentation focuses on some physical aspects affecting spatial groundwater recharge estimation and uncertainty associated with spatial variability. Previous wor...

341

Rechargeable Zn-MnO sub 2 alkaline batteries  

SciTech Connect

In this paper progress in the development of rechargeable alkaline zinc-manganese dioxide cells is described. The advantages and limitations of the system are evaluated. Laboratory tests run on commercial primary alkaline cells as well as model simulations of a bipolar MnO{sub 2} electrode show that the rechargeable alkaline battery may be able to compete with lead-acid, nickel-cadmium, and secondary lithium cells for low- to moderate-rate applications. However, because of this poor performance at high rates and low temperatures, the alkaline MnO{sub 2} battery is not suitable for present automotive starting applications.

Wruck, W.J.; Reichman, B.; Bullock, K.R.; Kao, W.H. (Corporate Applied Research, Johnson Controls, Inc., Milwaukee, WI (US))

1991-12-01

342

Modelling of recharge and pollutant fluxes to urban groundwaters.  

PubMed

Urban groundwater resources are of considerable importance to the long-term viability of many cities world-wide, yet prediction of the quantity and quality of recharge is only rarely attempted at anything other than a very basic level. This paper describes the development of UGIf, a simple model written within a GIS, designed to provide estimates of spatially distributed recharge and recharge water quality in unconfined but covered aquifers. The following processes (with their calculation method indicated) are included: runoff and interception (curve number method); evapotranspiration (Penman-Grindley); interflow (empirical index approach); volatilization (Henry's law); sorption (distribution coefficient); and degradation (first order decay). The input data required are: meteorological data, landuse/cover map with event mean concentration attributes, geological maps with hydraulic and geochemical attributes, and topographic and water table elevation data in grid form. Standard outputs include distributions of: surface runoff, infiltration, potential recharge, ground level slope, interflow, actual recharge, pollutant fluxes in surface runoff, travel times of each pollutant through the unsaturated zone, and the pollutant fluxes and concentrations at the water table. The process of validation has commenced with a study of the Triassic Sandstone aquifer underlying Birmingham, UK. UGIf predicts a similar average recharge rate for the aquifer as previous groundwater flow modelling studies, but with significantly more spatial detail: in particular the results indicate that recharge through paved areas may be more important than previously thought. The results also highlight the need for more knowledge/data on the following: runoff estimation; interflow (including the effects of lateral flow and channelling on flow times and therefore chemistry); evapotranspiration in paved areas; the nature of unsaturated zone flow below paved areas; and the role of the pipe network. Although considerably more verification is needed, UGIf shows promise for use: in providing input for regional groundwater solute transport models; in identifying gaps in knowledge and data; in determining which processes are the most important influences on urban groundwater quantity and quality; in evaluating existing recharge models; in planning, for example in investigation of the effects of landuse or climate change; and in assessing groundwater vulnerability. PMID:16325236

Thomas, Abraham; Tellam, John

2005-12-01

343

Changes to dunes caused by 4WD vehicle tracks in beach camping areas of Fraser Island  

Microsoft Academic Search

Although dunes are known to have very low tolerance to human disturbance and provide irreplaceable ecosystem services (e.g. erosion co ntrol, critical habitat and nesting sites), in dunes serve as campsites for large numbers of people (~ 90,000 p.a.) on the ocean-exposed shores of Fraser Island, Australia. On the island, camp sites are located in the established dunes and can

Thomas A. Schlacher; Luke M. C. Thompson

344

Changes in landscape and vegetation of coastal dunes in northwest Europe: a review  

Microsoft Academic Search

In coastal dunes, landscape changes are a rule, rather than an exception. This paper gives an overview of changes in landscape\\u000a and vegetation with a focus on the past century. The history of dunes is characterised by phases of sand drift, alternated\\u000a with geomorphological stability. The historical development of dune woodland during these stable phases has been documented\\u000a for sites

Sam Provoost; M. Laurence M. Jones; Sally E. Edmondson

2011-01-01

345

Lichens as indicators of a perturbation\\/stability gradient in the Asperillo dunes, SW spain  

Microsoft Academic Search

In the asperillo dune system, Southwest Spain, lichen vegetation covering the dune sand, has a low species diversity but is\\u000a an important component of the perennial vegetation, providing stability, nutrients, and moisture to the soil layer. The Asperillo\\u000a dunes harbour (1) natural ecosystems, (2) disturbed systems affected by forestry activities where the natural vegetation is\\u000a eliminated, and (3) pine forest

J. B. Gallego Fernández; M. C. Díaz Barradas

1997-01-01

346

Holocene dune-sourced alluvial fans in the Nebraska Sand Hills  

Microsoft Academic Search

The large, stabilized dunes of the Nebraska Sand Hills are in a phase of degradation. The deposition of small-scale alluvial fans composed of well-sorted, fine- to medium-grained sand occurs when sand is transported via gullies on the lee side of large barchanoid-ridge dunes during infrequent, intense summer rain storms (>5 cm\\/h). The hydraulic conductivity of the dune sand itself is

Mark R. Sweeney; David B. Loope

2001-01-01

347

La perception d’une discipline scolaire par les elèves. Représentation et effets identitaires  

Microsoft Academic Search

Résumé  La perception d’une discipline par les élèves est abordée comme relevant d’une construction visant à donner un sens à leur\\u000a réalité scolaire quotidienne et ne se réalisant donc pas indépendamment des conditions sociales de son élaboration, ni des\\u000a significations sociales attribuées à cette discipline et à ses contenus. Les résultats d’une enquête mennée en France auprès\\u000a d’élèves de niveau Collège

Michel Chambon

1990-01-01

348

Accelerated Dune Migration and Aeolian Transport During El Niño Events along the NE Brazilian Coast  

Microsoft Academic Search

MAIA, L.P.; FREIRE, G.S.S., and LACERDA, L.D., 2005. Accelerated dune migration and aeolian transport during El Nino events along the NE Brazilian coast. Journal of Coastal Research, 21(6), 1121-1126. West Palm Beach (Flor- ida), ISSN 0749-0208. Dune migration response to regional inter-annual climate variability in Ceara ´ , Northeastern Brazil was investigated. Dunes along the study area are mainly barchans

L. P. Maia; G. S. S. Freire; L. D. Lacerda

2005-01-01

349

Temporal and spatial variability of groundwater recharge on Jeju Island, Korea  

NASA Astrophysics Data System (ADS)

Baseline mean island-wide groundwater recharge was computed as 884 mm year-1.Baseline recharge rate was computed as 42% and below previous estimates of 44-48%.Recharge estimates are conservative and do not include irrigation or other sources.

Mair, Alan; Hagedorn, Benjamin; Tillery, Suzanne; El-Kadi, Aly I.; Westenbroek, Stephen; Ha, Kyoochul; Koh, Gi-Won

2013-09-01

350

Assessing the Impact of Land Use on Groundwater Recharge in the Southern High Plains  

Microsoft Academic Search

Although it is widely recognized that land use and land use changes can have a significant impact on the near surface water budget and groundwater recharge, field studies documenting the impact of land use on recharge are limited. The purpose of this study was to determine the role of land use on groundwater recharge using electromagnetic induction, soil physics (water

R. C. Reedy; B. R. Scanlon

2003-01-01

351

Impact of Land use Change From Natural to Agricultural Ecosystems on Groundwater Recharge  

Microsoft Academic Search

Recharge is a critical component of the water cycle for groundwater resources. The purpose of this study was to evaluate the impact of land use changes from natural to agricultural ecosystems on groundwater recharge in the Amargosa Desert, Nevada and Southern High Plains, Texas. A variety of approaches were used to evaluate groundwater recharge, including noninvasive electromagnetic induction, matric potential

B. R. Scanlon; R. C. Reedy; D. A. Stonestrom

2004-01-01

352

A battery recharge model for WSNs using Free-Space Optics (FSO)  

Microsoft Academic Search

One of the most critical limiting factor for a Wireless Sensor Network (WSN) is its battery life. Therefore, a very desirable feature of WSN would be its rechargability to remain operational over longer period of times. However, the nodes needing recharge may not be accessible. In this paper, we present a battery recharge model in WSNs for inaccessible or hard

Muhammd Imran Afzal; Waqar Mahmood; Ali Hammad Akbar

2008-01-01

353

Control circuit for a solar-powered rechargeable power source and load  

SciTech Connect

A solar rechargeable apparatus is described comprising: a rechargeable power source; a solar panel connected to the rechargeable power source for supplying a charging current to the rechargeable power source; a device connected between the rechargeable power source and the solar panel to prevent discharge of current from the rechargeable power source to the solar panel; a load; and a switching circuit connected between the load and the rechargeable power source and responsive to the potential of the solar panel and the potential of the rechargeable power source, the switching circuit operatively adapted to permit current to flow from the rechargeable power source through the load when the potential across the solar panel is less than the potential across the rechargeable power source, and further in which the switching circuit is further characterized as operatively adapted to permit current to flow from the rechargeable power source through the load when the potential across the solar panel is less than the combined potential across the rechargeable power source and a predetermined potential.

Janda, R.W.; Douglas, J.L.; Condon, E.F. Jr.

1993-06-22

354

Role of vegetation in interplay of climate, soil and groundwater recharge in a global dataset  

NASA Astrophysics Data System (ADS)

Groundwater is an essential resource for people and ecosystems worldwide. Our capacity to ameliorate predicted global water shortages and to maintain sustainable water supplies depend on a better understanding of the controls of recharge and how vegetation change may affect recharge mechanisms. The goals of this study are to quantify the importance of vegetation as a dominant control on recharge globally and to compare the importance of vegetation with other hydrologically important variables, including climate and soil. We based our global analysis on > 500 recharge estimates from the literature that contained information on vegetation, soil and climate or location. Plant functional types significantly affected groundwater recharge rates substantially. After climatic factors (water inputs, PET, and seasonality), vegetation types explained about 15% of the residuals in the dataset. Across all climatic factors, croplands had the highest recharge rates, followed by grasslands, scrublands and woodlands (average recharge: 75, 63, 30, 22 mm/yr respectively). Recharge under woodlands showed the most nonlinear response to water inputs. Differences in recharge between the vegetation types were more exaggerated at arid climates and in clay soils, indicating greater biological control on soil water fluxes in these conditions. Our results shows that vegetation greatly affects recharge rates globally and alters relationship between recharge and physical variables allowing us to better predict recharge rates globally.

Kim, J. H.; Jackson, R. B.

2010-12-01

355

Potential climate change effects on groundwater recharge in the High Plains Aquifer, USA  

NASA Astrophysics Data System (ADS)

Considering that past climate changes have significantly impacted groundwater resources, quantitative predictions of climate change effects on groundwater recharge may be valuable for effective management of future water resources. This study used 16 global climate models (GCMs) and three global warming scenarios to investigate changes in groundwater recharge rates for a 2050 climate relative to a 1990 climate in the U.S. High Plains region. Groundwater recharge was modeled using the Soil-Vegetation-Atmosphere-Transfer model WAVES for a variety of soil and vegetation types representative of the High Plains. The median projection under a 2050 climate includes increased recharge in the Northern High Plains (+8%), a slight decrease in the Central High Plains (-3%), and a larger decrease in the Southern High Plains (-10%), amplifying the current spatial trend in recharge from north to south. There is considerable uncertainty in both the magnitude and direction of these changes in recharge projections. Predicted changes in recharge between dry and wet future climate scenarios encompass both an increase and decrease in recharge rates, with the magnitude of this range greater than 50% of current recharge. On a proportional basis, sensitivity of recharge to changes in rainfall indicates that areas with high current recharge rates are least sensitive to change in rainfall and vice versa. Sensitivity analyses indicate an amplification of change in recharge compared to change in rainfall, and this amplification is in the range of 1-6 with an average of 2.5-3.5 depending upon the global warming scenario.

Crosbie, Russell S.; Scanlon, Bridget R.; Mpelasoka, Freddie S.; Reedy, Robert C.; Gates, John B.; Zhang, Lu

2013-07-01

356

Cassini SAR, radiometry, scatterometry and altimetry observations of Titan's dune fields  

NASA Astrophysics Data System (ADS)

Large expanses of linear dunes cover Titan's equatorial regions. As the Cassini mission continues, more dune fields are becoming unveiled and examined by the microwave radar in all its modes of operation (SAR, radiometry, scatterometry, altimetry) and with an increasing variety of observational geometries. In this paper, we report on Cassini's radar instrument observations of the dune fields mapped through May 2009 and present our key findings in terms of Titan's geology and climate. We estimate that dune fields cover ˜12.5% of Titan's surface, which corresponds to an area of ˜10 million km 2, roughly the area of the United States. If dune sand-sized particles are mainly composed of solid organics as suggested by VIMS observations (Cassini Visual and Infrared Mapping Spectrometer) and atmospheric modeling and supported by radiometry data, dune fields are the largest known organic reservoir on Titan. Dune regions are, with the exception of the polar lakes and seas, the least reflective and most emissive features on this moon. Interestingly, we also find a latitudinal dependence in the dune field microwave properties: up to a latitude of ˜11°, dune fields tend to become less emissive and brighter as one moves northward. Above ˜11° this trend is reversed. The microwave signatures of the dune regions are thought to be primarily controlled by the interdune proportion (relative to that of the dune), roughness and degree of sand cover. In agreement with radiometry and scatterometry observations, SAR images suggest that the fraction of interdunes increases northward up to a latitude of ˜14°. In general, scattering from the subsurface (volume scattering and surface scattering from buried interfaces) makes interdunal regions brighter than the dunes. The observed latitudinal trend may therefore also be partially caused by a gradual thinning of the interdunal sand cover or surrounding sand sheets to the north, thus allowing wave penetration in the underlying substrate. Altimetry measurements over dunes have highlighted a region located in the Fensal dune field (˜5° latitude) where the icy bedrock of Titan is likely exposed within smooth interdune areas. The hemispherical assymetry of dune field properties may point to a general reduction in the availability of sediments and/or an increase in the ground humidity toward the north, which could be related to Titan's asymmetric seasonal polar insolation. Alternatively, it may indicate that either the wind pattern or the topography is less favorable for dune formation in Titan's northern tropics.

Le Gall, A.; Janssen, M. A.; Wye, L. C.; Hayes, A. G.; Radebaugh, J.; Savage, C.; Zebker, H.; Lorenz, R. D.; Lunine, J. I.; Kirk, R. L.; Lopes, R. M. C.; Wall, S.; Callahan, P.; Stofan, E. R.; Farr, T.; the Cassini Radar Team

357

Declining sand dune activity in the southern Canadian prairies: Historical context, controls and ecosystem implications  

NASA Astrophysics Data System (ADS)

Sandhills are islands of biodiversity in the southern Canadian prairies that sustain habitat for many rare and endangered species. These unique areas consist of large expanses of dune fields now mostly stabilized by grassland vegetation. Historically, the number of active dunes has decreased significantly due to vegetation stabilization, resulting in a dramatic decline of open-sand habitat for a variety of dune-dependent species. Without a certain level of wind erosion, opportunities for establishment of early-stage, species-rich vegetation types are diminished and open-sand habitat decreases by encroachment of the surrounding grassland vegetation. The current trend of dune stabilization, however, implies that wind erosion is decreasing, thereby threatening the continued existence of a variety of dune-dependent plants, arthropods and vertebrates, as well as other less-specialized species that benefit indirectly from these habitats. By reviewing factors contributing to the historical decline of active dunes, as well as the ecological implications of dune stabilization, the aim of this paper is to establish the biophysical context for new land management strategies that conserve valued landscape components, such as active dunes, and the processes therein. As dune stabilization continues management interventions will be required to sustain or re-establish open sand and the species that rely on these habitats.

Hugenholtz, Chris H.; Bender, Darren; Wolfe, Stephen A.

2010-11-01

358

Dunes on Saturn's moon Titan as revealed by the Cassini Mission  

NASA Astrophysics Data System (ADS)

Dunes on Titan, a dominant landform comprising at least 15% of the surface, represent the end product of many physical processes acting in alien conditions. Winds in a nitrogen-rich atmosphere with Earth-like pressure transport sand that is likely to have been derived from complex organics produced in the atmosphere. These sands then accumulate into large, planet-encircling sand seas concentrated near the equator. Dunes on Titan are predominantly linear and similar in size and form to the large linear dunes of the Namib, Arabian and Saharan sand seas. They likely formed from wide bimodal winds and appear to undergo average sand transport to the east. Their singular form across the satellite indicates Titan's dunes may be highly mature, and may reside in a condition of stability that permitted their growth and evolution over long time scales. The dunes are among the youngest surface features, as even river channels do not cut through them. However, reorganization time scales of large linear dunes on Titan are likely tens of thousands of years. Thus, Titan's dune forms may be long-lived and yet be actively undergoing sand transport. This work is a summary of research on dunes on Titan after the Cassini Prime and Equinox Missions (2004-2010) and now during the Solstice Mission (to end in 2017). It discusses results of Cassini data analysis and modeling of conditions on Titan and it draws comparisons with observations and models of linear dune formation and evolution on Earth.

Radebaugh, Jani

359

Can beach dune ridges of the Texas Gulf Coast preserve climate signals?  

NASA Astrophysics Data System (ADS)

A study of the evolution of North Padre Island (southern Texas Gulf Coast) dunes was carried out using LIDAR topographic data, dune vibracores through the center of the dunes, and grab samples of shoreface sand at four locations along a cross-shore profile. Grain-size analyses of the vibracores show vertical variations in shoreface sand deposition over decimeter depth intervals. A dune ridge growth model is introduced that describes the dune vertical accretion rate as a function of island progradation and freshwater lens expansion. This model allows indirect dating of the dune core samples based on a known island progradation rate (1 m/year), and height and spacing of the dunes calculated from the topographic data. A sand provenance model is also proposed that links the sand deposition in the dunes with sand sourced from various depths along the shoreface profile, depending on storm activity. We present evidence linking the changes in storm-sand deposition in the dune cores with yearly climatic fluctuations in the Gulf of Mexico associated with landfalling tropical storm activity in the period from 1942-1965. This record of storm-induced sand variability is negatively correlated with El Niño-Southern Oscillation (Pacific) sea surface temperature variability, and positively correlated with North Atlantic decadal sea surface temperature variability.

Garrison, James R.; Mestas-Nuñez, Alberto M.; Williams, Joshua R.; Lumb, Luz M.

2012-06-01

360

An agent-based model of dune interactions produces the emergence of patterns in deserts  

NASA Astrophysics Data System (ADS)

Crescent-shaped barchan dunes are highly mobile dunes which are ubiquitous on Earth and other solar system bodies. Although they are unstable when considered separately, they form large assemblies in deserts and spatially organize in narrow corridors that extend in the wind direction. Collision of barchans has been proposed as a mechanism to redistribute sand between dunes and prevent the formation of very large dunes. Here we use an agent-based model with elementary rules of sand redistribution during collisions to access the full dynamics of very large barchan fields. We tune the dune field density by changing the sand load/lost ratio and follow the transition between dilute fields, where barchans barely interact, and dense fields, where dune collisions control and stabilize the dune field. In this dense regime, barchans have a small, well-selected size and form flocks: the dune field self-organizes in narrow corridors of dunes, as it is observed in real dense barchan deserts.

GéNois, Mathieu; Pont, Sylvain Courrech; Hersen, Pascal; GréGoire, Guillaume

2013-08-01

361

PRINCIPALS OF ORGANIC CONTAMINANT BEHAVIOR DURING ARTIFICIAL RECHARGE  

EPA Science Inventory

The behavior of a variety of organic contaminants having low molecular weight has been observed during groundwater recharge with reclaimed water. The evidence is site-specific, but is believed to have broader implications regarding the general behavior of organic contaminants in ...

362

PRIORITY POLLUTANTS IN THE CEDAR CREEK WASTEWATER RECLAMATION - RECHARGE FACILITIES  

EPA Science Inventory

The Cedar Creek Wastewater Reclamation Plant (CCWRP) located in Nassau County, NY is a 0.24 cu m/s (5.5 mgd) advanced wastewater treatment (AWT) plant designed to produce a high quality effluent suitable for groundwater recharge. The CCWRP was constructed as a demonstration proje...

363

WASTEWATER CONTAMINATE REMOVAL FOR GROUNDWATER RECHARGE AT WATER FACTORY 21  

EPA Science Inventory

This is the second report in a series which describes the performance of Water Factory 21, a 0.66 cu m/s advanced wastewater treatment plant designed to reclaim secondary effluent from a municipal wastewater treatment plant so that it can be used for injection and recharge of a g...

364

Carbon materials for lithium-ion rechargeable batteries  

Microsoft Academic Search

The recent development of lithium rechargeable batteries results from the use of carbon materials as lithium reservoir at the negative electrode. Reversible intercalation, or insertion, of lithium into the carbon host lattice avoids the problem of lithium dendrite formation and provides large improvement in terms of cycleability and safety. This paper reviews the main achievements on performance and understanding of

S. Flandrois; B. Simon

1999-01-01

365

Moderate temperature rechargeable NaNiS2 cells  

Microsoft Academic Search

A rechargeable sodium battery of the configuration, liquid Na\\/beta double prime -Al2O3\\/molten NaAlCl4, NiS2, operating in the temperature range of 170 to 190 C, is described. This battery is capable of delivering or = to 50 W-hr\\/1b and 1000 deep discharge\\/charge cycles.

K. M. Abraham

1983-01-01

366

Moderate temperature rechargeable NaNiS2 cells  

NASA Astrophysics Data System (ADS)

A rechargeable sodium battery of the configuration, liquid Na/beta double prime -Al2O3/molten NaAlCl4, NiS2, operating in the temperature range of 170 to 190 C, is described. This battery is capable of delivering or = to 50 W-hr/1b and 1000 deep discharge/charge cycles.

Abraham, K. M.

1983-10-01

367

Effects of recharge wells and flow barriers on seawater intrusion.  

PubMed

The installation of recharge wells and subsurface flow barriers are among several strategies proposed to control seawater intrusion on coastal groundwater systems. In this study, we performed laboratory-scale experiments and numerical simulations to determine the effects of the location and application of recharge wells, and of the location and penetration depth of flow barriers, on controlling seawater intrusion in unconfined coastal aquifers. We also compared the experimental results with existing analytical solutions. Our results showed that more effective saltwater repulsion is achieved when the recharge water is injected at the toe of the saltwater wedge. Point injection yields about the same repulsion compared with line injection from a screened well for the same recharge rate. Results for flow barriers showed that more effective saltwater repulsion is achieved with deeper barrier penetration and with barriers located closer to the coast. When the flow barrier is installed inland from the original toe position however, saltwater intrusion increases with deeper barrier penetration. Saltwater repulsion due to flow barrier installation was found to be linearly related to horizontal barrier location and a polynomial function of the barrier penetration depth. PMID:20533955

Luyun, Roger; Momii, Kazuro; Nakagawa, Kei

368

Rechargeable lithium batteries in the Navy-policy and protocol  

Microsoft Academic Search

Rechargeable lithium batteries are an emerging technology that is finding widespread use in a myriad of applications. These batteries are supplanting many others because of superior performance characteristics, including high energy density and improved cycle life. The newest model laptop computers, camcorders and cellular phones are using these systems to provide lighter products with longer battery life. Potential military-use scenarios

Julie A. Banner; Clinton S. Winchester

1996-01-01

369

Issue and challenges facing rechargeable thin film lithium batteries  

Microsoft Academic Search

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. Technological improvements in rechargeable solid-state batteries

Arun Patil; Vaishali Patil; Dong Wook Shin; Ji-Won Choi; Dong-Soo Paik; Seok-Jin Yoon

2008-01-01

370

Application of electrochemically formed polyazulene to rechargeable lithium battery  

Microsoft Academic Search

An electrochemically formed polyazulene(PAz), one of the electroconductive polycyclic hydrocarbons, was studied for its electrochemical properties in order to examine the possibility of utilizing it as a cathode active material of rechargeable lithium battery. The electrode kinetics of PAz film electrode, especially the anion doping-undoping process, were investigated mainly with cyclic voltammetry and FFT impedance method. The cyclic voltammetric results

Tetsuya Osaka; K. Naoi; T. Hirabayashi

1987-01-01

371

GIS for the assessment of the groundwater recharge potential zone  

NASA Astrophysics Data System (ADS)

Water resources in Taiwan are unevenly distributed in spatial and temporal domains. Effectively utilizing the water resources is an imperative task due to climate change. At present, groundwater contributes 34% of the total annual water supply and is an important fresh water resource. However, over-exploitation has decreased groundwater availability and has led to land subsidence. Assessing the potential zone of groundwater recharge is extremely important for the protection of water quality and the management of groundwater systems. The Chih-Pen Creek basin in eastern Taiwan is examined in this study to assess its groundwater resources potential. Remote sensing and the geographical information system (GIS) are used to integrate five contributing factors: lithology, land cover/land use, lineaments, drainage, and slope. The weights of factors contributing to the groundwater recharge are derived using aerial photos, geology maps, a land use database, and field verification. The resultant map of the groundwater potential zone demonstrates that the highest recharge potential area is located towards the downstream regions in the basin because of the high infiltration rates caused by gravelly sand and agricultural land use in these regions. In contrast, the least effective recharge potential area is in upstream regions due to the low infiltration of limestone.

Yeh, Hsin-Fu; Lee, Cheng-Haw; Hsu, Kuo-Chin; Chang, Po-Hsun

2009-07-01

372

GIS for the Assessment of the Groundwater Recharge Potential Zone  

NASA Astrophysics Data System (ADS)

Water resources in Taiwan are unevenly distributed in spatial and temporal domains. Effectively utilizing the water resources is an imperative task due to climate change. At present, groundwater contributes 34% of the total annual water supply and is an important fresh water resource. However, over-exploitation has decreased groundwater availability and has led to land subsidence. Assessing the potential zone of groundwater recharge is extremely important for the protection of water quality and the management of groundwater systems. The Chih-Pen Creek basin in eastern Taiwan is examined in this study to assess its groundwater resources potential. Remote sensing and the Geographical Information System (GIS) are used to integrate five contributing factors: lithology, land cover/land use, lineaments, drainage, and slope. The weights of factors contributing to the groundwater recharge are derived using aerial photos, geology maps, a land use database, and field verification. The resultant map of the groundwater potential zone demonstrates that the highest recharge potential area is located towards the downstream regions in the basin because of the high infiltration rates caused by gravelly sand and agricultural land use in these regions. In contrast, the least effective recharge potential area is in upstream regions due to the low infiltration of limestone.

Lee, C.; Yeh, H.; Chen, J.; Hsu, K.

2008-12-01

373

Bubble plumes generated during recharge of basaltic magma reservoirs  

Microsoft Academic Search

CO2 is relatively insoluble in basaltic magma at low crustal pressures. It therefore exists as a gas phase in the form of bubbles in shallow crustal reservoirs. Over time these bubbles may separate gravitationally from the magma in the chamber. As a result, any new magma which recharges the chamber from deeper in the crust may be more bubble-rich and

J. C. Phillips; A. W. Woods

2001-01-01

374

LOCALIZED RECHARGE INFLUENCES ON MTBE TRANSPORT AND WELL PLACEMENT CONSIDERATIONS  

EPA Science Inventory

Vertical characterization of a gasoline release site at East Patchogue, New York showed that methyl tert-butyl ether (MTBE) and aromatic plumes "dived" as they passed beneath a sand pit. That this behavior was caused by aquifer recharge was shown by two pieces of evidence. Fir...

375

System and circuit for charging a rechargeable battery  

Microsoft Academic Search

A system and circuit for charging a rechargeable battery from an external source of direct current is provided wherein the circuit includes an indicator for indicating the passage of charge current through the circuit. The circuit precludes the indicator from providing a false indication of the passage of charging current.

Mullersman

1984-01-01

376

System and circuit for charging a rechargeable battery  

SciTech Connect

A system and circuit for charging a rechargeable battery from an external source of direct current is provided wherein the circuit includes an indicator for indicating the passage of charge current through the circuit. The circuit precludes the indicator from providing a false indication of the passage of charging current.

Mullersman, F. H.

1984-12-25

377

Rechargeable battery and electrical circuit for charging thereof  

SciTech Connect

This patent describes a nickel-cadmium rechargeable cell for use in an energy-using device having at least one charging terminal contact for recharging the cell. The energy-using device adapted to alternately receive either a standard cylindrical AA, AAA, C or D size non-rechargeable cell has a pair of power terminal contacts spaced apart by a standard distance. The rechargeable cell comprises: a hollow cylindrical cell container one end of which provides an axially facing negative power terminal contact; a cell cover disposed at the other end of the cylindrical cell and electrically insulated form the container and the cover cooperating with the container to seal the interior of the cell from the environment external thereto. The cover has a positive power terminal contact surface spaced apart from the negative power terminal contact by a distance equal to the standard distance, the cover further having a terminal extension carried by the cover and extending axially away from the cell container. The terminal extension has a terminal extension charging contact surface adapted to engage the charging terminal contact of the energy-using device, the surface spaced apart from the negative power terminal contact by a distance greater than the standard distance.

Toops, K.E.

1987-02-24

378

A Wireless Power Interface for Rechargeable Battery Operated Medical Implants  

Microsoft Academic Search

This brief presents a highly integrated wirelessly powered battery charging circuit for miniature lithium (Li)-ion rechargeable batteries used in medical implant applications. An inductive link and integrated Schottky barrier rectifying diodes are used to extract the DC signal from a power carrier while providing low forward voltage drop for improved efficiency. The battery charger employs a new control loop that

Pengfei Li; Rizwan Bashirullah

2007-01-01

379

Hysteresis in Thin-Film Rechargeable Lithium Batteries.  

National Technical Information Service (NTIS)

Discharge - charge cycling of thin-film rechargeable lithium batteries with an amorphous or nanocrystalline LiXMn2.Y04 cathode reveals evidence for a true hysteresis in the lithium insertion reaction. This is compared with an apparent hysteresis attribute...

J. B. Bates N. J. Dudney C. D. Evans F. X. Hart

1999-01-01

380

High power, rechargeable, pile type silver zinc battery  

Microsoft Academic Search

This patent describes a high rate rechargeable silver-zinc pile type battery including a plurality of bipolar electrodes which are assembled into a full scale multi-cell pile. Each of bipolar electrodes includes a positive side having a porous silver matrix attached to silver foil and a negative side having a porous zinc structure vapor deposited on silver foil. A separator including

L. R. Erisman; R. A. Marsh

1978-01-01

381

Separation composition evaluation in model rechargeable silver-zinc cells  

Microsoft Academic Search

In previous reports, the evaluation of Viskase sausage casings (SCs) in a variety of configurations for silver\\/zinc rechargeable cells has been reported. The conclusions have been that several layers of SC, while providing improved resistance to silver migration acid zinc dendrite growth compared to standard cellophane film, also impart increased internal impedance which leads to faster capacity loss in comparison

H. Lewis; S. Henderson; T. Danko

2001-01-01

382

Uncertainty in Climatology-Based Estimates of Shallow Groundwater Recharge  

Microsoft Academic Search

The groundwater recharge (GR) estimates for flow and transport projections are often evaluated as a fixed percentage of average annual precipitation. The chemical transport in variably saturated heterogeneous porous media is not linearly related to the average velocity. The objective of this study was to estimate the variability in annual, seasonal, and event-based GR at the field scale and to

A. K. Guber; Y. Pachepsky; T. J. Gish; T. J. Nicholson; R. R. Cady

2007-01-01

383

Trench infiltration for managed aquifer recharge to permeable bedrock  

USGS Publications Warehouse

Managed aquifer recharge to permeable bedrock is increasingly being utilized to enhance resources and maintain sustainable groundwater development practices. One such target is the Navajo Sandstone, an extensive regional aquifer located throughout the Colorado Plateau of the western United States. Spreading-basin and bank-filtration projects along the sandstone outcrop's western edge in southwestern Utah have recently been implemented to meet growth-related water demands. This paper reports on a new cost-effective surface-infiltration technique utilizing trenches for enhancing managed aquifer recharge to permeable bedrock. A 48-day infiltration trench experiment on outcropping Navajo Sandstone was conducted to evaluate this alternative surface-spreading artificial recharge method. Final infiltration rates through the bottom of the trench were about 0.5 m/day. These infiltration rates were an order of magnitude higher than rates from a previous surface-spreading experiment at the same site. The higher rates were likely caused by a combination of factors including the removal of lower permeability soil and surficial caliche deposits, access to open vertical sandstone fractures, a reduction in physical clogging associated with silt and biofilm layers, minimizing viscosity effects by maintaining isothermal conditions, minimizing chemical clogging caused by carbonate mineral precipitation associated with algal photosynthesis, and diminished gas clogging associated with trapped air and biogenic gases. This pilot study illustrates the viability of trench infiltration for enhancing surface spreading of managed aquifer recharge to permeable bedrock. ?? 2010.

Heilweil, V. M.; Watt, D. E.

2011-01-01

384

A rechargeable non-aqueous Mg-O2 battery.  

PubMed

We propose a catalytic cycle using the iodine-dimethylsulfoxide (I2-DMSO) complex for the realization of secondary Mg-O2 batteries. We have demonstrated that the Mg-O2 battery incorporating an I2-DMSO complex electrolyte showed evidence of being rechargeable. PMID:23985777

Shiga, Tohru; Hase, Yoko; Kato, Yuichi; Inoue, Masae; Takechi, Kensuke

2013-08-29

385

Electrolytes for rechargeable lithium batteries. Research and development technical report  

SciTech Connect

Theoretical considerations predict increased stability of cyclic ethers and diethers against reductive cleavage by lithium if the ethers have 2 methyl substitution. Diethers are solvents with low viscosity which are desirable for high rate rechargeable lithium batteries. Synergistic, mixed solvent effects increase electrolyte conductance and rate capability of lithium intercalating cathodes.

Hunger, H.F.

1981-09-01

386

Climate change effects on vegetation characteristics and groundwater recharge  

Microsoft Academic Search

Climate change is among the most pressing issues of our time. Increase in temperature, a decrease in summer precipitation and increase in reference evapotranspiration might affect the water balance, freshwater availability and the spatial distribution and type of vegetation. Precipitation and evapotranspiration (ET) largely determine groundwater recharge. Therefore, climate change likely affects both the spatial and temporal freshwater availability for

2010-01-01

387

A polymer electrolyte-based rechargeable lithium\\/oxygen battery  

Microsoft Academic Search

A novel rechargeable Li\\/Oâ battery is reported. It comprises a Li{sup +} conductive organic polymer electrolyte membrane sandwiched by a thin Li metal foil anode, and a thin carbon composite electrode on which oxygen, the electroactive cathode material, accessed from the environment, is reduced during discharge to generate electric power. It features an all solid state design in which electrode

K. M. Abraham; Z. Jiang

1996-01-01

388

Climate Change Effects on Yucca Mountain Region Groundwater Recharge  

Microsoft Academic Search

Groundwater geochemical data from 211 sampling locations in the Amargosa Desert region are analyzed to better understand the general flow system and climate-induced changes in recharge around Fortymile Wash near Yucca Mountain. Major ion groundwater chemistry was examined using the multivariate statistical methods of principal component analysis and k-means cluster analysis. These analyses showed several groundwater signatures, or potential flowpaths;

Arturo Woocay; John C. Walton

2006-01-01

389

Potential for Recharge in Agricultural Soils of the Mississippi Delta  

NASA Astrophysics Data System (ADS)

Ground water models predict that 5 percent or less of precipitation in the Mississippi Delta region recharges the heavily-used alluvial aquifer; however the presence of agricultural chemicals in ground water suggests more substantial recharge. In a preliminary assessment of the potential for aerial recharge through the agricultural soils of the Bogue Phalia basin in the Mississippi Delta, we applied a method for rapidly measuring field- saturated hydraulic conductivity (Kfs) in 26 locations in cotton and soybean fields. The technique makes use of a portable falling-head, small-diameter, single-ring infiltrometer and an analytical formula for Kfs that compensates both for falling head and for subsurface radial spreading. Soil samples were also collected at the surface and at about 6 cm depth at each location for particle size analysis. Kfs values are generally higher than anticipated and vary over more than three orders of magnitude from 1x10-2 to 5x10-6 cm/s. There is also a correlation between Kfs and mean particle size which may prove useful in generalizing recharge rates over larger areas. A 2-m ring infiltration test is planned that will include the use of tracers and subsurface instruments for measuring water content and matric potential from the near surface to about 5 m to evaluate flow and transport below the root zone.

Perkins, K. S.; Nimmo, J. R.; Coupe, R. H.; Rose, C. E.; Manning, M. A.

2007-12-01

390

Lithium-Air Battery: Study of Rechargeability and Scalability.  

National Technical Information Service (NTIS)

Lithium-air battery is anticipated as the battery with highest energy density among all existing rechargeable battery systems known now. Literature reports suggest that the theoretical energy density of Li-air battery is close to that of gasoline. Thus, i...

M. Nookala

2012-01-01

391

Rechargeable zinc air batteries market and technology overview  

Microsoft Academic Search

AER Energy Resources is an Atlanta based technology company that has developed a rechargeable zinc air battery system. The primary advantage of the AER Energy Advanced Technology Battery is that its energy density on a weight basis is three times that of nickel cadmium, nickel metal hydride and lead acid batteries, and fifty percent higher than lithium ion batteries. This

M. Schimpf

1995-01-01

392

Ecohydrologic process modeling of mountain block groundwater recharge.  

PubMed

Regional mountain block recharge (MBR) is a key component of alluvial basin aquifer systems typical of the western United States. Yet neither water scientists nor resource managers have a commonly available and reasonably invoked quantitative method to constrain MBR rates. Recent advances in landscape-scale ecohydrologic process modeling offer the possibility that meteorological data and land surface physical and vegetative conditions can be used to generate estimates of MBR. A water balance was generated for a temperate 24,600-ha mountain watershed, elevation 1565 to 3207 m, using the ecosystem process model Biome-BGC (BioGeochemical Cycles) (Running and Hunt 1993). Input data included remotely sensed landscape information and climate data generated with the Mountain Climate Simulator (MT-CLIM) (Running et al. 1987). Estimated mean annual MBR flux into the crystalline bedrock terrain is 99,000 m(3) /d, or approximately 19% of annual precipitation for the 2003 water year. Controls on MBR predictions include evapotranspiration (radiation limited in wet years and moisture limited in dry years), soil properties, vegetative ecotones (significant at lower elevations), and snowmelt (dominant recharge process). The ecohydrologic model is also used to investigate how climatic and vegetative controls influence recharge dynamics within three elevation zones. The ecohydrologic model proves useful for investigating controls on recharge to mountain blocks as a function of climate and vegetation. Future efforts will need to investigate the uncertainty in the modeled water balance by incorporating an advanced understanding of mountain recharge processes, an ability to simulate those processes at varying scales, and independent approaches to calibrating MBR estimates. PMID:19702780

Magruder, Ian A; Woessner, William W; Running, Steve W

2009-08-20

393

Remote sensing and spatial analysis of aeolian sand dunes: A review and outlook  

NASA Astrophysics Data System (ADS)

For more than four decades remote sensing images have been used to document and understand the evolution of aeolian sand dunes. Early studies focused on mapping and classifying dunes. Recent advances in sensor technology and software have allowed investigators to move towards quantitative investigation of dune form evolution and pattern development. These advances have taken place alongside progress in numerical models, which are capable of simulating the multitude of dune patterns observed in nature. The potential to integrate remote sensing (RS), spatial analysis (SA), and modeling to predict the future changes of real-world dune systems is steadily becoming a reality. Here we present a comprehensive review of significant recent advances involving RS and SA. Our objective is to demonstrate the capacity of these technologies to provide new insight on three important research domains: (1) dune activity, (2) dune patterns and hierarchies, and (3) extra-terrestrial dunes. We outline how several recent advances have capitalized on the improved spatial and spectral resolution of RS data, the availability of topographic data, and new SA methods and software. We also discuss some of the key research challenges and opportunities in the application of RS and SA dune field, including: the integration of RS data with field-based measurements of vegetation cover, structure, and aeolian transport rate in order to develop predictive models of dune field activity; expanding the observational evidence of dune form evolution at temporal and spatial scales that can be used to validate and refine simulation models; the development and application of objective and reproducible SA methods for characterizing dune field pattern; and, expanding efforts to quantify three-dimensional topographic changes of dune fields in order to develop improved understanding of spatio-temporal patterns of erosion and deposition. Overall, our review indicates a progressive evolution in the way sand dunes are studied: whereas traditional field studies of airflow and sand transport can clarify event-based process-form interactions, investigators are realizing a synoptic perspective is required to address the response of dune systems to major forcings. The integration and evolution of the technologies discussed in this review are likely to form a foundation for future advances in aeolian study.

Hugenholtz, Chris H.; Levin, Noam; Barchyn, Thomas E.; Baddock, Matthew C.

2012-03-01

394

How much liquid water was there on Martian dunes?  

NASA Astrophysics Data System (ADS)

Presently, liquid water unlikely to be found on the surface of Mars because of atmospheric pressure/temperature conditions below water's triple-point. However, gullies discovered by Malin and Edgett (2000) suggest that significant amounts of liquid water has flowed on Mars in the recent past. These gullies are among the youngest features on Mars based on the scarcity of cratered gullies (Heldmann et al., 2007) and their superposition on relatively young formations such as dunes. Several hypotheses have been suggested for the formation of gullies: (i) runoff and debris flows with liquid water from groundwater aquifers (Heldmann and Mellon, 2004; Malin et al., 2000), (ii) snow-melt (Christensen, 2003; Dickson et al, 2007), (iii) liquid CO2 breakout (Musselwhite et al., 2001), (iv) melting of near-surface ground ice (< 1 m meter) at high obliquity (Costard et al., 2002), (v) geothermal-heated aquifers (Gaidos, 2001; Hartmann, 2001), (vi) the presence of brines (Knauth et al., 2000; Knauth and Burt, 2003). This study focuses on gully morphologies on the Russell megadune (54.5°S; 12.7°E) and in Kaiser crater (46.2°S; 19.1°E) using High Resolution Imaging Science Experiment (HiRISE) images and Digital Terrain Models (DTM). Gullies on terrestrial sand dunes are rare, and their presence on Mars, as well as their mechanical properties, and the quantity of fluid required for their formation currently remain misunderstood. Based on the scenario of ground ice melting in a periglacial environment, we propose to test the hypothesis that Martian gullies on dunes were triggered by the presence of liquid water. The calculated results for Martian gullies are consistent with terrestrial studies on debris flows. Based on a morphological description and on the estimated physical parameters, we propose a model for gully formation on Martian dunes. The melt water from near-surface ground ice is incorporated in the debris flow and water concentration increases during its propagation. The increase of water concentration in the debris flow can be explained by a progressive increase of water/ice content in the permafrost downslope. Consequently, the lack of a final deposit at the front of some gullies tends to demonstrate that the flow became relatively highly concentrated in liquid downstream and all the water could have been lost in the final stage of the flow. Here we quantify the quantity of liquid necessary to form such a morphology.

Gargani, J.; Jouannic, G.; Costard, F.; Ori, G. G.; Marmo, C.; Schmidt, F.; Lucas, A.; Busson, J.

2012-04-01

395

Classification of ground-water recharge potential in three parts of Santa Cruz County, California  

USGS Publications Warehouse

Ground-water recharge potential was classified in the Santa Cruz coastal area, North-central area, and Soquel-Aptos area in Santa Cruz County, Calif., for three data elements that affect recharge; slope, soils, and geology. Separate numerical maps for each element were composited into a single numerical map using a classification system that ranked the numbers into areas of good , fair, and poor recharge potential. Most of the Santa Cruz coastal area and the Norht-central area have a poor recharge potential, and much of the Soquel-Aptos area has a good to fair recharge potential. (Kosco-USGS)

Muir, K. S.; Johnson, Michael J.

1979-01-01

396

An overview of experiences of basin artificial recharge of ground water in Japan  

NASA Astrophysics Data System (ADS)

In this paper, the author reviews the present situation of basin artificial recharge of ground water (MAR: managed aquifer recharge) as of 2007 in Japan. Most of the artificial recharge of basin method is carried out using alluvial fans. The enhancing groundwater resources in the Rokugo alluvial aquifer has resulted in sustainability for the groundwater environment, especially in the distal fan. As a general judgment, the basin artificial recharge contributes to sustainable aquifer management in alluvium. As a result of this review, the basin artificial recharge will be utilized more in the future, not only in Japan, but in monsoon Asian countries as well.

Hida, Noboru

397

Dune recovery after storm erosion on a high-energy beach: Vougot Beach, Brittany (France)  

NASA Astrophysics Data System (ADS)

On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of "secondary" embryo dunes, which recovered at an average rate of 4-4.5 cm per month, although average monthly volume changes varied from - 1 to 2 m3.m- 1. These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000 m3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone.

Suanez, Serge; Cariolet, Jean-Marie; Cancouët, Romain; Ardhuin, Fabrice; Delacourt, Christophe

2012-02-01

398

Hazard Impact And Genetic Development Of SandDunes West Of Nile Valley Egypt Egypt  

NASA Astrophysics Data System (ADS)

A SE. dune field extends west of Nile Vally (west Samalut). The dune movement and sand encroachment on the cultivated fields along the margins of the Nile flood plain represents a permanent threat to soil productivity and agricultural production in this region. In this study, the dunes has been investigated by producing geological and geomorphological maps by using Landsa ETM images for the area surrounding the dune field. Fifty sand samples had been collected from sand dunes and 5 samples were collected from substratum. Each field observation locality could be considered as a profile across the sand dune direction of movements. The sand samples are sieved and the separate samples weighed. Carrying out the collective diagrams using the computer program SITA. The granulometric indices were calculated, that is the mean grain diameter, standard deviation (measure of sorting) and skeweens Besides the sand grain features were analyzed, that is grain rounding with the use of a graniformameter, and by undertaking laboratory investigations on samples collected from various dunes. The laboratory investigations involve different granulometric parameters such as the grain rounding and frosting in the binocular microscope and morphoscopic studies. Morphoscopic studies using scanning electronic microscope (SEM) elucidate the surface process affected on sand grains. These dunes seem to have their source from a location found to the north, east and from the substratum of the dunes probably from the extensive sand and gravel deposits of Oligocene and Miocene and Quaternary age. While the sand are shiny and more rounded mat grains in the northern part of these dunes to fluvial processes. However it is not excluded that part of the sediments of the dunes are old intensively reworked aeolian sediments moving in the Western Desert during various arid phases of the Quaternary. SE movement of sands due to wind and become more markedly "aeolinized" in this direction by including less rounded and striated sand grains. They also include less clay material toward the south.

Asayed El Gammal, El; El Din El Sayed, Alaa

2010-05-01

399

Process for recharging secondary batteries. [Vapor transport of S during recharging improved by maintaining temperature gradient in cathodic reaction zone  

Microsoft Academic Search

An improved process is described for recharging secondary cells or batteries of the type which in the discharged state comprise (a) an anodic reaction zone containing a molten alkali metal reactant-anode in electrical contact with an external circuit; (b) a cathodic reaction zone containing (1) cathodic reactants selected from the group consisting of (i) a single-phase composition comprising molten polysulfide

R. W. Minck; N. Weber; Y. Chang

1976-01-01

400

Probabilistic analysis of the effects of climate change on groundwater recharge  

NASA Astrophysics Data System (ADS)

Groundwater recharge is likely to be affected by climate change. In semiarid regions where groundwater resources are often critical, annual recharge rates are typically small and most recharge occurs episodically. Such episodic recharge is uncertain and difficult to predict. This paper analyzes the impacts of different climate predictions on diffuse episodic recharge at a low-relief semiarid rain-fed agricultural area. The analysis relies on a probabilistic approach that explicitly accounts for uncertainties in meteorological forcing and in soil and vegetation properties. An ensemble of recharge forecasts is generated from Monte Carlo simulations of a study site in the southern High Plains, United States. Soil and vegetation parameter realizations are conditioned on soil moisture and soil water chloride observations (Ng et al., 2009). A stochastic weather generator provides realizations of meteorological time series for climate alternatives from different general circulation models. For most climate alternatives, predicted changes in average recharge (spanning -75% to +35%) are larger than the corresponding changes in average precipitation (spanning -25% to +20%). This suggests that amplification of climate change impacts may occur in groundwater systems. Predictions also include varying changes in the frequency and magnitude of recharge events. The temporal distribution of precipitation change (over seasons and rain events) explains most of the variability in predictions of recharge totals and episodic occurrence. The ensemble recharge analysis presented in this study offers a systematic approach to investigating interactions between uncertainty and nonlinearities in episodic recharge.

Ng, Gene-Hua Crystal; McLaughlin, Dennis; Entekhabi, Dara; Scanlon, Bridget R.

2010-07-01

401

A New Method for Estimating Recharge to Unconfined Aquifers Using Differential River Gauging.  

PubMed

In semiarid and arid environments, leakage from rivers is a major source of recharge to underlying unconfined aquifers. Differential river gauging is widely used to estimate the recharge. However, the methods commonly applied are limited in that the temporal resolution is event-scale or longer. In this paper, a novel method is presented for quantifying both the total recharge volume for an event, and variation in recharge rate during an event from hydrographs recorded at the upstream and downstream ends of a river reach. The proposed method is applied to river hydrographs to illustrate the method steps and investigate recharge processes occurring in a sub-catchment of the Murray Darling Basin (Australia). Interestingly, although it is the large flood events which are commonly assumed to be the main source of recharge to an aquifer, our analysis revealed that the smaller flow events were more important in providing recharge. PMID:23550897

McCallum, Andrew M; Andersen, Martin S; Acworth, R Ian

2013-04-01

402

Hydrometeorological daily recharge assessment model (DREAM) for the Western Mountain Aquifer, Israel: Model application and effects of temporal patterns  

Microsoft Academic Search

Recharge is a critical issue for water management. Recharge assessment and the factors affecting recharge are of scientific and practical importance. The purpose of this study was to develop a daily recharge assessment model (DREAM) on the basis of a water balance principle with input from conventional and generally available precipitation and evaporation data and demonstrate the application of this

N. A. Sheffer; E. Dafny; H. Gvirtzman; S. Navon; A. Frumkin; E. Morin

2010-01-01

403

Combined estimation of specific yield and natural recharge in a semi-arid groundwater basin with irrigated agriculture  

Microsoft Academic Search

A water budget approach is developed to jointly estimate specific yield and natural recharge in an unconfined aquifer with significant seasonal water table fluctuations. Water table fluctuations are due to distinct seasonality in groundwater recharge. The separation of the hydrologic year into two (or more) extended seasons of recharge (wet season) and no-recharge (dry season) with accompanying changes in water

J. C. Maréchal; B. Dewandel; S. Ahmed; L. Galeazzi; F. K. Zaidi

2006-01-01

404

Quantifying Landscape \\/ Ecological Succession in a Coastal Dune System Using Sequential Aerial Photography and GIS  

Microsoft Academic Search

This chapter presents an attempt to measure the path of habitat and vegetation succession in a coastal dune system (Kenfig NNR, south Wales) using remote sensing and GIS. The loss of slack habitats associated with the continuing stabilization of this dune system is a major cause for concern. These habitats support a range of plant species, including the rare fen

S. Shanmugam; M. Barnsley

405

Remotely sensed dune celerity and sand flux measurements of the world's fastest barchans (Bodélé, Chad)  

NASA Astrophysics Data System (ADS)

Quantifying sand flux with field measurements is an expensive and time-consuming process. We here present an alternative approach using the COSI-Corr software package for Earth surface deformation detection. Using pairs of ASTER satellite images, we detected dune migration in the Bodélé depression of northern Chad over time intervals of one month to 6.5 years. The displacement map can be used to automatically distinguish dunes from interdunes, which is a crucial step towards calculating sand flux. We interpolated a surface between the interdune areas and subtracted it from a digital elevation model, thus obtaining dune heights and volumes. Multiplying height with celerity yields a pixel-by-pixel estimate of the sand flux. We applied this method to large diatomite dunes in the Bodélé, confirming that these are some of the world's fastest moving barchans. Plotting dune height against inverse celerity reveals sand flux at the dune crest of >200 m3/m/yr. Average dune sand flux values for the eastern and western Bodélé are 76 and 99 m3/m/yr, respectively. The contribution of the dunes to the total area-averaged sand flux is 24-29 m3/m/yr, which is ~10% of the saltation flux determined by previously published field measurements.

Vermeesch, Pieter; Drake, Nick

2008-12-01

406

Response of sand dunes to variations in tidal flow: Fraser Estuary, Canada  

Microsoft Academic Search

The morphology of dunes in rivers and estuaries often lags behind changes in river discharge and neap-spring tides. This study extends previous research by examining the response of large subtidal dunes in the Fraser Estuary, Canada, to changing flow conditions over a semidiurnal tidal cycle. An acoustic Doppler current profiler (ADCP) is used to measure three-dimensional velocity profiles and estimate

Ray Kostaschuk; Jim Best

2005-01-01

407

A Beach and Dune Community. 4-H Marine Science. Member's Guide. Activity I. MSp 1.  

ERIC Educational Resources Information Center

|The investigation in this booklet is designed to provide 4-H members with opportunities to identify common plants and animals found on beaches and sand dunes and to determine the role of the plants and animals in this community. Learners are provided with a picture of a hypothetical beach and sand dune and a list of organisms (included in the…

Auburn Univ., AL. Cooperative Extension Service.

408

Remobilization of southern African desert dune systems by twenty-first century global warming.  

PubMed

Although desert dunes cover 5 per cent of the global land surface and 30 per cent of Africa, the potential impacts of twenty-first century global warming on desert dune systems are not well understood. The inactive Sahel and southern African dune systems, which developed in multiple arid phases since the last interglacial period, are used today by pastoral and agricultural systems that could be disrupted if climate change alters twenty-first century dune dynamics. Empirical data and model simulations have established that the interplay between dune surface erodibility (determined by vegetation cover and moisture availability) and atmospheric erosivity (determined by wind energy) is critical for dunefield dynamics. This relationship between erodibility and erosivity is susceptible to climate-change impacts. Here we use simulations with three global climate models and a range of emission scenarios to assess the potential future activity of three Kalahari dunefields. We determine monthly values of dune activity by modifying and improving an established dune mobility index so that it can account for global climate model data outputs. We find that, regardless of the emission scenario used, significantly enhanced dune activity is simulated in the southern dunefield by 2039, and in the eastern and northern dunefields by 2069. By 2099 all dunefields are highly dynamic, from northern South Africa to Angola and Zambia. Our results suggest that dunefields are likely to be reactivated (the sand will become significantly exposed and move) as a consequence of twenty-first century climate warming. PMID:15988522

Thomas, David S G; Knight, Melanie; Wiggs, Giles F S

2005-06-30

409

Preliminary observations on managing and reclaiming frontal dunes within the Durban municipal area  

Microsoft Academic Search

The Bluff dunes, located within the Durban (South Africa) municipal area, have become increasingly degraded as a consequence of human pressures over the last quarter century. The resulting localised wind-blown sand pollution of roads and storm drains necessitated a dune reclamation project involving a multi-disciplinary team of Parks managers and engineers. An effective solution was provided by a combination of

G. R. Nichols

1996-01-01

410

Foraging behaviour of donkeys grazing in a coastal dune area in temperate climate conditions  

Microsoft Academic Search

A small herd of donkeys was introduced in a coastal dune reserve ‘Houtsaegerduinen’ (ca. 80ha) in Belgium, in order to slow down expansion of dominant grass and shrub species. The Houtsaegerduinen is a nutrient poor scrub-dominated dune system with a spatially heterogeneous vegetation pattern. Different aspects of the grazing behaviour (grazing time, bite rate, habitat use, diet composition) of the

Indra Lamoot; Julie Callebaut; Else Demeulenaere; Charlotte Vandenberghe; Maurice Hoffmann

2005-01-01

411

A Dune Simulation Wind Tunnel for Studies of Lee Face Processes  

Microsoft Academic Search

Sand is deposited on the lee slope of dunes by grainfall, avalanching (grainflow), and wind ripple migration. These processes play major roles in the formation of aeolian cross strata. Grainfall is produced by saltating grains that are blown over the dune crest and fall on the lee slope. Avalanching occurs when sand on the lee slope fails and the resulting

K. Cupp; N. Lancaster; W. G. Nickling

2004-01-01

412

The Influence of Complex Systems Interactions on Barrier Island Dune Vegetation Pattern and Process  

Microsoft Academic Search

Studies of dune vegetation patterns have emphasized two structuring agents: local environmental gradients that shape the prominent zonation of coastal plant species, and disturbance patches initiated by overwash during coastal storms. For dune systems of two barrier islands in the Georgia Bight, we investigate how the interplay of these two conceptual frames generate patterns in (1) longitudinal (along-shore) and transverse

J. Anthony Stallins; Albert J. Parker

2003-01-01

413

Dune Retreat and Shoreline Change on the Outer Banks of North Carolina  

NASA Astrophysics Data System (ADS)

Barrier islands are popular recreational areas of economic importance that are constantly changing. Costly efforts are made to maintain beaches and stabilize dunes within this dynamic environment. We examine one year of coastal change along the barrier islands of the North Carolina Outer Banks. LIDAR data collected in September of 1997 and 1998 along a 175 km stretch of the Atlantic coast of the North Carolina Outer Banks provide the basis for quantitative determination of changes in beach morphology. The survey of 1998 was conducted a few days after the passage of Hurricane Bonnie. Hurricane Bonnie provided a unique opportunity to study factors that influence coastal change because after making landfall it traveled roughly parallel to the coastline, causing relatively uniform storm conditions along a long reach of coast. During the one-year study interval, beach widths throughout the study region tended to decrease. We determined the maximum dune retreat for each 1 m bin of 1997 beach width in different parts of the Outer Banks. Maximum dune retreat was greatest for beach widths of approximately 20 m and for dune base elevations less than 4.0 m. For comparable beach widths, maximum dune retreat increased from south to north. The undeveloped natural beaches of the Core Banks experienced relatively little change in beach width, dune height and dune base position. The greatest morphological changes occurred on Ocracoke Island and Hatteras Island where the dunes had been stabilized and the beaches had been artificially maintained.

Burroughs, S. M.; Tebbens, S. F.

2005-12-01

414

Comparing the Effectiveness of Ground-Penetrating Radar in Imaging Siliciclastic And Mafic- Volcaniclastic Dune Sands  

NASA Astrophysics Data System (ADS)

Experiments using ground-penetrating radar (GPR) systems in two, different dune sediment environments allow comparisons of the relative effectiveness of subsurface imaging and feature detection. One experiment was carried out in the Coral Pink Sand Dunes (CPSD) in southern Utah, and a second in the Grand County Off Road Vehicle area in Moses Lake (ML), Washington. Both experiments used a MALA GPR system with 500MHz antenna and similar data sampling and acquisition parameters. The dunes at the CPSD site are comprised of nearly pure, very well sorted quartz sands. These sharply contrast with dunes at the ML site which are comprised of basalt-rich (up to 80%) sands. The ML site was selected as a terrestrial analog to Martian dunes that have been shown in other studies to have a similar mineralogy. As with other quartz dune studies, radar images gathered at the CPSD site clearly show cross-bedding structures and were able to identify the bedrock/dune interface as well as the locally shallow water table. The imagery collected at the ML site was not as clear, but some dune structures, ash beds, and water are visible in the imagery. We propose that thee higher basalt content at the ML sites results in greater signal loss than in the siliciclastic sands at the CPSD site. The reduced signal transmissivity in the mafic sands may have implications for selection of GPR instrumentation in future Mars investigations.

Wilkins, D. E.; Clement, W.

2007-12-01

415

Aeolian Dunes as Evidence for Explosive Volcanism in the Tharsis Region of Mars  

Microsoft Academic Search

Two transverse dune fields occur among Late Amazonian volcanic and aeolian landforms in southwestern Tharsis, Mars. The first is located ?70 km northwest of Biblis Patera, around 5°N, 125°W. The second is located about 500 km northwest of Arsia Mons, at 2°S, 130°W. The latter is the largest dune field thus far documented to occur in the equatorial latitudes of

Kenneth S. Edgett

1997-01-01

416

Direct seeding of grass species for sand dune stabilization on the mid-Atlantic sea coast  

Microsoft Academic Search

The stabilization of moving sand dunes at Provincetown, Massachusetts, depends, to a large degree, upon the environmental factors of wind, temperature and rainfall. Direct seedings of grasses for the purpose of stilling these moving dunes can be wiped out totally by the severe northeast and northwest winds which occur in the very early spring. In this study, 9 different mulches

J. M. Zak

1977-01-01

417

The effect of sparse vegetation on the transport of dune sand by wind  

Microsoft Academic Search

The precise effect of a sparse plant cover on the transport of dune sand by wind is a critical factor in understanding the morphology, evolution and global distribution of aeolian dunes1-3. It is also of considerable practical importance in sand stabilization, rehabilitation and restoration ecology. Here I report the first detailed experimental quantification of this effect using living plants in

Ralf Buckley

1987-01-01

418

Population ecology on an environmental gradient: Cakile edentula on a sand dune  

Microsoft Academic Search

A naturally-occurring sand dune population of the annual plant Cakile edentula (Brassicaceae) was studied for two years. The plants grew along an environmental gradient stretching from open sand beach (seaward) to densely vegetated dunes (landward). Survivorship and reproductive output were estimated from plants in permanent quadrats. The dispersal of seeds was documented by sifting fruits from the sand substrate at

Paul A. Keddy

1982-01-01

419

Laboratory investigation of beach scarp and dune recession due to notching and subsequent failure  

Microsoft Academic Search

Analytical models to calculate notch development and subsequent mass failure of dunes are presented. The notch evolution model is based on a transport equation for sediment from the dune and the sediment volume conservation equation, whereas the models of mass failure are derived using elementary engineering statics and soil mechanics. An empirical transport coefficient in the model describing the notch

Li H. Erikson; Magnus Larson; Hans Hanson

2007-01-01

420

Very large dune formation along the Ebro outer continental shelf (Western Mediterranean)  

Microsoft Academic Search

Large and very large subaqueous dunes have been observed in a number of outer shelf regions around the world, tipically developing on fossil sand bodies and ridges. Dunes observed on outer shelves usually display large dimensions with maximum wavelength reaching up to 500 m and heights up to 20 m. Forcing mechanisms able to induce their formation have been described

Claudio Lo Iacono; Jorge Guillén; Pere Puig; Marta Ribó; Maria Ballesteros; Albert Palanques; Marcelli Farrán; Juan Acosta

2010-01-01

421

Coupling the dynamics of boundary layers and evolutionary dunes.  

PubMed

A theoretical formulation and corresponding numerical solutions are presented for fluid flow and sediment transport past evolutionary sand dunes. Time-dependent curvilinear coordinates are employed to fully couple flow aloft with the developing landform. The differential conservation law that defines shape of the lower boundary depends on details of local surface stress, thereby favoring the large eddy simulation of the boundary layer. To shrink the gap between the time scales characteristic of planetary boundary layer flows O(10(3)) s and sand dune evolution O(10(6)) s, a hypothetical "severe-wind scenario" is adopted with the saltation flux amplified up to 3 orders of magnitude. While the results are largely insensitive to the rescaling, the efficacy of computations is greatly improved. The flux-form partial differential equation for the interface profile--via saltation and sand avalanches--is formulated as an advection-diffusion equation, to facilitate discrete integrations. Numerical experiments verify the adopted theoretical framework by reproducing scaling results reported in the literature. The versatility of the approach is illustrated with evolution of a sandhole--an example of application likely never addressed in the literature, yet realizable in nature. PMID:19518224

Ortiz, Pablo; Smolarkiewicz, Piotr K

2009-04-20

422

Morphological thresholds for the definition of the vulnerability of coastal dunes in northern Italy  

NASA Astrophysics Data System (ADS)

The Emilia Romagna coastline is located in northern Italy, facing the Adriatic Sea. It is characterised by natural areas with dunes and urbanised zones. This work only relates with natural areas in order to define storm thresholds able to generate morphological changes on coastal dunes. The main morphological impact is related to the dune system only, generating dune frontal erosion and/or overtopping and dune destruction. The chosen indicator of this morphological impact is the Dune Stability Factor (DSF, Fig. 1) that describes the most probable effect of a storm on the dune system and was the factor consequently used to define wave height and surge levels able to generate significant morphological changes. The methodology used for identifying the threshold includes three important dynamic factors (waves, tide and surge) plus detailed topographic information. The contribution of the sea elevation to inundation/damages was analysed using surge and tidal levels, while the contribution of storms was included into the run-up computation (max Water Level=tide+surge+run-up). Waves, tide and surge levels were extracted from literature considering three “worst” scenarios where a storm with 1, 10 and 100 years return period occurs at the same time as a surge with the same return periods and at the same time as a high spring tide of +0.45m above MSL. The computed max WL was used to calculate the DSF and to define vulnerability categories along the coastline. If the DSF ? 20% the dune is considered vulnerable to complete removal and erosion. If DSF is between 20% and 75% the dune is considered vulnerable to frontal erosion. Finally, if DSF is above 75% the dune is not believed to be vulnerable. To define the DSF percentage values listed above, a comparison was made between measured profiles before and after registered storms. There are some exceptions that do not show a correspondence with the percentages defined above but in general there is a good agreement between the DSF-predicted vulnerability and the observed erosion (70%/90%). The analysis of the morphological impact along natural areas reveals that the joint occurrence of the 1-yr return period wave+the 1-yr return period surge+high spring tide leads to dune erosion and overtopping. This conclusion derives from the analysis of the results of the DSF computation that shows how 60% of the whole studied profiles are damaged by the sea state described above. Figure 1: Dune Stability Factor = (A_dunefoot/A_hmax)*100 where A_dunefoot is the dune cross-sectional area, A_hmax is the cross sectional area calculated between the max water level (for each scenario) and the dune crest

Armaroli, C.; Ciavola, P.; Masina, M.

2009-12-01

423

Mapping a local Dune Field, and estimating paleowind speed and direction  

NSDL National Science Digital Library

Students map one large hairpin parabolic dune in the Pinebush Preserve. They also profile the slopes on both proximal and distal sides of the dune. As a group, we take an ~ 2m long core of the dune sand to sample the sand beneath the soil profile. In the lab, students measure the particle size distribution of their sand samples, map the whole dune field from aerial photographs and a DEM, and estimate paleo-wind speed and direction. They then compare these data with modern wind data (available from the web) to answer the question of .just how different conditions were when the dune field was deposited Uses online and/or real-time data Addresses student fear of quantitative aspect and/or inadequate quantitative skills Uses geomorphology to solve problems in other fields

Rodbell, Donald T.

424

Short-term changes in mobile dunes at Port Alfred, South Africa  

NASA Astrophysics Data System (ADS)

Development along the western beachfront of Port Alfred, which is situated along a sandy shoreline, increased markedly in the 1960s as the coastal town became a popular holiday resort. This development included the removal of coastal vegetation, which resulted in the destabilization of dunes and migration of sand westerly onto the road, West Beach parking lot, and lawns of the cabanas. Sand traps were constructed to collect sand blowing across the dunes over set periods, and the net sand movement along the mobile dune belt was calculated using Hunter's equation. The dunes show an easterly movement of sand at a rate of 3.5 m/yr, which is comparable with figures recorded along other areas of this coastline. Considering the wind regime and amount of sand movement along this coast, it is inappropriate to clear vegetation and develop within the dune region.

Lubke, Roy A.; Sugden, Jean

1990-03-01

425

Remote sensing of soil moisture: implications for groundwater recharge  

NASA Astrophysics Data System (ADS)

Remote sensing provides information on the land surface. Therefore, linkages must be established if these data are to be used in groundwater and recharge analyses. Keys to