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1

White Sands, Carrizozo Lava Beds, NM  

NASA Technical Reports Server (NTRS)

A truly remarkable view of White Sands and the nearby Carrizozo Lava Beds in southeast NM (33.5N, 106.5W). White Sands, site of the WW II atomic bomb development and testing facility and later post war nuclear weapons testing that can still be seen in the cleared circular patterns on the ground.

1973-01-01

2

Coupled changes in sand grain size and sand transport driven by changes in the upstream supply of sand in the Colorado River: Relative importance of changes in bed-sand grain size and bed-sand area  

USGS Publications Warehouse

Sand transport in the Colorado River in Marble and Grand canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in sediment concentration, (2) hysteresis in sediment grain size coupled to the hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4) development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Construction and operation of the dam has enhanced the degree to which the first two of these four effects are evident, and has not affected the degree to which the last two effects of sand supply limitation are evident in the Colorado River in Marble and Grand canyons. The first three of the effects involve coupled changes in suspended-sand concentration and grain size that are controlled by changes in the upstream supply of sand. During tributary floods, sand on the bed of the Colorado River fines; this causes the suspended sand to fine and the suspended-sand concentration to increase, even when the discharge of water remains constant. Subsequently, the bed is winnowed of finer sand, the suspended sand coarsens, and the suspended-sand concentration decreases independently of discharge. Also associated with these changes in sand supply are changes in the fraction of the bed that is covered by sand. Thus, suspended-sand concentration in the Colorado River is likely regulated by both changes in the bed-sand grain size and changes in the bed-sand area. A physically based flow and suspended-sediment transport model is developed, tested, and applied to data from the Colorado River to evaluate the relative importance of changes in the bed-sand grain size and changes in the bed-sand area in regulating suspended-sand concentration. Although the model was developed using approximations for steady, uniform flow, and other simplifications that are not met in the Colorado River, the results nevertheless support the idea that changes in bed-sand grain size are much more important than changes in bed-sand area in regulating the concentration of suspended sand.

Topping, D. J.; Rubin, D. M.; Melis, T. S.

2007-01-01

3

Coupled changes in sand grain size and sand transport driven by changes in the upstream supply of sand in the Colorado River: Relative importance of changes in bed-sand grain size and bed-sand area  

NASA Astrophysics Data System (ADS)

Sand transport in the Colorado River in Marble and Grand canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in sediment concentration, (2) hysteresis in sediment grain size coupled to the hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4) development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Construction and operation of the dam has enhanced the degree to which the first two of these four effects are evident, and has not affected the degree to which the last two effects of sand supply limitation are evident in the Colorado River in Marble and Grand canyons. The first three of the effects involve coupled changes in suspended-sand concentration and grain size that are controlled by changes in the upstream supply of sand. During tributary floods, sand on the bed of the Colorado River fines; this causes the suspended sand to fine and the suspended-sand concentration to increase, even when the discharge of water remains constant. Subsequently, the bed is winnowed of finer sand, the suspended sand coarsens, and the suspended-sand concentration decreases independently of discharge. Also associated with these changes in sand supply are changes in the fraction of the bed that is covered by sand. Thus, suspended-sand concentration in the Colorado River is likely regulated by both changes in the bed-sand grain size and changes in the bed-sand area. A physically based flow and suspended-sediment transport model is developed, tested, and applied to data from the Colorado River to evaluate the relative importance of changes in the bed-sand grain size and changes in the bed-sand area in regulating suspended-sand concentration. Although the model was developed using approximations for steady, uniform flow, and other simplifications that are not met in the Colorado River, the results nevertheless support the idea that changes in bed-sand grain size are much more important than changes in bed-sand area in regulating the concentration of suspended sand.

Topping, D. J.; Rubin, D. M.; Melis, T. S.

2007-12-01

4

20. View of sand filtration bed. Wheelbarrow was used to ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. View of sand filtration bed. Wheelbarrow was used to remove schmutzdeck (top, dirty sand layer containing particulate contamination, dead microorganisms and debris) for cleaning and or disposal. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

5

Arsenate removal from water using sand–red mud columns  

Microsoft Academic Search

This study describes experiments in which sorption filters, filled with chemically modified red mud (Bauxsol) or activated Bauxsol (AB) coated sand, are used to remove As(V) (arsenate) from water. Bauxsol-coated sand (BCS) and AB-coated sand (ABCS) are prepared by mixing Bauxsol or AB with wet sand and drying. Samples of the BCS and ABCS are also used in batch experiments

Hülya Genç-Fuhrman; Henrik Bregnhøja; David M McConchie

2005-01-01

6

Modeling downstream fining in sand-bed rivers. I: Formulation  

USGS Publications Warehouse

In this paper a numerical modeling formulation is presented for simulation of the development of the longitudinal profile and bed sediment distribution in sand-bed rivers. The objective of the model application, which is presented in the companion paper (Wright and Parker, 2005), is to study the development of two characteristics of large, low-slope, sand-bed rivers: (1) a downstream decrease in bed slope (i.e. concave upward longitudinal profile) and (2) a downstream decrease in characteristic bed sediment diameter (e.g. the median bed surface size D50). Three mechanisms that lead to an upward concave profile and downstream fining are included in the modeling formulation: (1) a delta prograding into standing water at the downstream boundary, (2) sea-level rise, and (3) tectonic subsidence. In the companion paper (Wright and Parker, 2005) the model is applied to simulate the development of the longitudinal profile and downstream fining in sand-bed rivers flowing into the ocean during the past 5000 years of relatively slow sea-level rise. ?? 2005 International Association of Hydraulic Engineering and Research.

Wright, S.; Parker, G.

2005-01-01

7

Nitrogen removal in a combined system: vertical vegetated bed over horizontal flow sand bed  

Microsoft Academic Search

Pig farm wastewater creates various problems in many areas throughout Thailand. Constructed wetland systems are an appropriate, low cost treatment option for tropical countries such as Thailand. In this study, a combined system (a vertical flow bed planted with Cyperus flabelliformis over a horizontal flow sand bed without plants) was used to treat settled pig farm wastewater . This system

S. Kantawanichkul; P. Neamkam; R. B. E. Shutes

8

Near-bed turbulent flow hydrodynamics in gravel-bedded streams subjected to imposed sand transport.  

NASA Astrophysics Data System (ADS)

Sand grain-sizes may be found in excess in mountain rivers as a result of erosion of unprotected soil in the catchment. By triggering changes in the river morphodynamics, this may result in severe changes in the turbulent flow hydrodynamics. This study is aimed at the characterization of the near-bed turbulent flow in gravel-bedded rivers subjected to imposed sand transport. Special emphasis is given to the mean velocity profiles, to the stress terms in the equation of conservation of momentum and to the production terms in the equation of conservation of turbulent kinetic energy (TKE). To accomplish the proposed objectives, conditions similar to those found in nature, in what concerns the flow and the characteristics of the bed material, were reproduced in the laboratory. Three experimental tests simulated different stream conditions: (i) undisturbed openwork gravel bed; (ii) framework-supported gravel bed with a sand matrix and, (iii) framework-supported gravel bed with imposed sand transport at near-capacity conditions. Instantaneous velocity maps were obtained with Particle Image Velocimetry (PIV). The collected data was analysed and theoretically framed with double-averaged methods (DAM). Changes in the velocity profiles, in form-induced and Reynolds stresses and in TKE production terms are discussed vis-à-vis changes in the bed texture associated to different rates of sediment transport.

Ferreira, R.; Ferreira, L.; Ricardo, A.; Franca, M.

2009-04-01

9

Anomalous Dispersion in a Sand Bed River  

NASA Astrophysics Data System (ADS)

There has been a recent surge of interest in non-local, heavy-tailed models of sediment transport and dispersion that are governed by fractional order differential equations. These models have a firm mathematical foundation and have been successfully applied in a variety of transport systems, but their use in geomorphology has been minimal because the data required to validate the models is difficult to acquire. We use data from a nearly 50-year-old tracer experiment to test a fluvial bed load transport model with a two unique features. First, the model uses a heavy-tailed particle velocity distribution with a divergent second moment to reproduce the anomalously high fraction of tracer mass observed in the downstream tail of the spatial distribution. Second, the model partitions mass into a detectable mobile phase and an undetectable, immobile phase. This two-phase transport model predicts two other features observed in the data: a decrease in the amount of detected tracer mass over the course of the experiment and the high initial velocity of the tracer plume. Because our model uses a heavy-tailed velocity distribution with a divergent second moment it is non-local and non-Fickian and able to reproduce aspects of the data that a local, Fickian model cannot. The model's successful prediction of the observed concentration profiles provides some of the first evidence of anomalous dispersion of bed load in a natural river.

Bradley, D. N.; Tucker, G. E.; Benson, D. M.

2009-04-01

10

Bed load transport of sand mixtures in estuaries: A review  

NASA Astrophysics Data System (ADS)

Real estuaries are fundamentally inhomogeneous. This is evident in their irregular boundaries, waters of varying density, fluid motions that arise from multiple unsteady forcings, and sediments that are mixtures of various grain sizes. In the paper, a review is given of the influence of one of these heterogeneities, namely, mixed particle size, on the transport of sand as bed load. Essential early studies and recent complete theories are discussed. Present-day investigators commonly assume a reference transport function (RTF) which is any established formulation for the flux of bed load under steady unidirectional flow over a substrate of monosized particles. The aim of the modern work is to develop a procedure which yields tailored values of sheltering-exposure coefficients for the different size fractions. These coefficients are correction factors which when applied to the acting bed shear permit the use of the RTF to compute fraction transports over a mixed bed. There are strong interactions among the various size fractions; for instance, minor admixture of a coarse-end ingredient disproportionately reduces the overall mobility of a finer-grained bed. However, coarse fractions are more mobile in a bed of mixed sizes than they are in a bed of the same uniform size. Recommendations are made for an estuarine field study utilizing a modified Helley-Smith bed load yield sampler.

Ludwick, John C.

1989-10-01

11

Vegetation-driven morphodynamic adjustments of a sand bed  

NASA Astrophysics Data System (ADS)

is ubiquitous in riverine and coastal environments, but the physics governing morphodynamic interactions modulated by vegetation are still poorly understood. Here we use a simple experiment to study the impact of a vegetated patch on the morphodynamics of a sand bed. We show that the vegetation patch reduces the sediment transport capacity of the flow and that the topography responds to this by an increase of the bed slope to accommodate the upstream sediment supply. Final bed slope and adjustment time scale depend on the ratio between the grain-related shear stress and the total shear stress. This demonstrates the mechanisms underlying a direct morphodynamic response to the presence of a vegetation patch.

Le Bouteiller, Caroline; Venditti, Jeremy G.

2014-06-01

12

Comparison of Bacteria Populations in Clean and Recycled Sand used for Bedding in Dairy Facilities  

Microsoft Academic Search

Bedding samples were collected twice from commer- cial dairy free-stall facilities that used recycled sand and clean sand in both the summer and winter. Collec- tion began on the day sand was taken from the pile (d 0) and placed in the free stalls, and continued for 5 to 7 additional days. The number of colonies per gram of bedding

M. A. Kristula; W. Rogers; J. S. Hogan; M. Sabo

2005-01-01

13

The influence of sand bed temperature on lift-off and falling parameters in windblown sand flux  

NASA Astrophysics Data System (ADS)

In deserts the temperature of the sand bed can reach up to more than 50 °C, however, existing knowledge on the lift-off and falling velocities and angles of sand particles in windblown sand flux is based mainly on experimental results over a temperature range of 20 °C to 30 °C. Consequently, existing experimental results cannot reflect the actual interaction between saltating sands and the bed. In this study, the influence of the sand bed temperature on the probability distribution of lift-off and falling velocities and angles of sand particles is investigated through an improved Particle Image Velocimetry (PIV) system. Results demonstrate that the distribution shape of lift-off and falling velocities and angles of sand particles is not greatly influenced by the temperature of sand bed, however it has a certain influence on the center of the probability distributions of horizontal velocities, as well as the average, decay constant and amplitude of the distributions of vertical velocities and angles. We present formulas to describe the probability distributions of lift-off and falling velocities and angles with regard to the influence of sand bed temperature.

Bo, Tian-Li; Duan, Shao-Zhen; Zheng, Xiao-Jing; Liang, Yi-Rui

2014-01-01

14

Acoustic bed velocity and bed load dynamics in a large sand bed river  

USGS Publications Warehouse

Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profiles (ADCPs) has emerged as a promising approach for evaluating bed load transport. However, a better understanding of how ADCP data relate to conditions near the stream bed is necessary to make the method practical for quantitative applications. In this paper, we discuss the response of ADCP bed velocity measurements, defined as the near-bed sediment velocity detected by the instrument's bottom-tracking feature, to changing sediment-transporting conditions in the lower Missouri River. Bed velocity represents a weighted average of backscatter from moving bed load particles and spectral reflections from the immobile bed. The ratio of bed velocity to mean bed load particle velocity depends on the concentration of the particles moving in the bed load layer, the bed load layer thickness, and the backscatter strength from a unit area of moving particles relative to the echo strength from a unit area of unobstructed bed. A model based on existing bed load transport theory predicted measured bed velocities from hydraulic and grain size measurements with reasonable success. Bed velocities become more variable and increase more rapidly with shear stress when the transport stage, defined as the ratio of skin friction to the critical shear stress for particle entrainment, exceeds a threshold of about 17. This transition in bed velocity response appears to be associated with the appearance of longer, flatter bed forms at high transport stages.

Gaeuman, D.; Jacobson, R. B.

2006-01-01

15

Australian Red Dune Sand: A Potential Martian Regolith Analog  

NASA Technical Reports Server (NTRS)

To demonstrate the potential scientific and technical merits of in situ microscopy on Mars, we analyzed a possible Martian regolith analog - an acolian red dune sand from the central Australian desert (near Mt. Olga). This sand was chosen for its ubiquitous red coating and the desert environment in which is it found. Grains of this sand were analyzed using a variety of microanalytical techniques. A database of detailed studies of such terrestrial analogs would assist the study of geological and astrobiological specimens in future missions to Mars. Potential instrument concepts for in situ deployment on Mars include local electrode atom probe nanoanalysis (LEAP), vertical scanning white light interferometry (VSWLI), scanning electron microscopies, energy dispersive x-ray microanalysis (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD). While in situ deployment of these techniques is many years away, ground-based studies using these analytical techniques extend our understanding of the data obtained from instruments to be flown in the near future.

Kuhlman, K. R.; Marshall, J.; Evans, N. D.; Luttge, A.

2001-01-01

16

The sand-deposition impact of artificial gravel beds on the protection of the Mogao Grottoes  

PubMed Central

Gravel beds can prevent sand-dust emission and weaken sand-dust flux. We used wind-tunnel experiments and field observations on artificial gravel beds above the Mogao Grottoes to quantify their impact. In the report, we identified a significant correlation between gravel roughness and its ability to trap wind-transported sand. The optimal combinations of gravel diameter and coverage were determined. The greatest roughness is achieved when small gravel coverage is 75%, medium 40% and large 45%. We found that initial wind speed and gravel coverage are the key factors controlling the amount of sand trapped by the gravel beds.

Li, Guo Shuai; Qu, Jian Jun; Li, Xu Zhi; Wang, Wan Fu

2014-01-01

17

Modeling downstream fining in sand-bed rivers. II: Application  

USGS Publications Warehouse

In this paper the model presented in the companion paper, Wright and Parker (2005) is applied to a generic river reach typical of a large, sand-bed river flowing into the ocean in order to investigate the mechanisms controlling longitudinal profile development and downstream fining. Three mechanisms which drive downstream fining are studied: a delta prograding into standing water, sea-level rise, and tectonic subsidence. Various rates of sea-level rise (typical of the late Holocene) and tectonic subsidence are modeled in order to quantify their effects on the degree of profile concavity and downstream fining. Also, several other physical mechanisms which may affect fining are studied, including the relative importance of the suspended versus bed load, the effect of the loss of sediment overbank, and the influence of the delta bottom slope. Finally, sensitivity analysis is used to show that the grain-size distribution at the interface between the active layer and substrate has a significant effect on downstream fining. ?? 2005 International Association of Hydraulic Engineering and Research.

Wright, S.; Parker, G.

2005-01-01

18

Flow resistance and suspended load in sand-bed rivers: Simplified stratification model  

USGS Publications Warehouse

New methods are presented for the prediction of the flow depth, grain-size specific near-bed concentration, and bed-material suspended sediment transport rate in sand-bed rivers. The salient improvements delineated here all relate to the need to modify existing formulations in order to encompass the full range of sand-bed rivers, and in particular large, low-slope sand-bed rivers. They can be summarized as follows: (1) the inclusion of density stratification effects in a simplified manner, which have been shown in the companion paper to be particularly relevant for large, low-slope, sand-bed rivers; (2) a new predictor for near-bed entrainment rate into suspension which extends a previous relation to the range of large, low-slope sand-bed rivers; and (3) a new predictor for form drag which again extends a previous relation to include large, low-slope sand-bed rivers. Finally, every attempt has been made to cast the relations in the simplest form possible, including the development of software, so that practicing engineers may easily use the methods. ?? ASCE.

Wright, S.; Parker, G.

2004-01-01

19

Inclination Error Correction In Red Beds: Is It Possible ?  

NASA Astrophysics Data System (ADS)

Highly detailed records - including processing of hundreds of samples - have been obtained from red beds in southern France, in the Dôme de Barrot and Lodève basins. The main purpose was to sample and determine paleosecular variation (PSV) - over sufficient time - during the Permian Superchron. We compared our records with older and earlier published literature data, and generally find good agreement. Since (hematite bearing) red beds are famous for their inclination error, we tried to correct our distributions using two independent methods. One method is using a PSV model (TK03.GAD; Tauxe and Kent, 2004) which - not surprisingly for such low latitudes - gives no significant correction on the distributions that sufficiently sample PSV. In addition, our data are in very good agreement with published APWP data, giving confidence in the recording qualities of these red beds, at least at paleoequatorial latitudes. Another method is to correct the inclination via an approach (the "a- factor"of Tan and Kodama, 2002) that uses the anisotropies of the magnetic susceptibility and of laboratory acquired (anhysteretic or isothermal) remanence. To this end, we sampled single layers, that we assumed to record - approximately - one single occurrence of PSV. A model approach was used to estimate the a-factor, rather than determining this parameter from laboratory experiments. We also used TK03.GAD on a large distribution (N=~200) of these single layer samples. This yielded interesting results. In one case a positive inclination was corrected - via the a- factor model - to a negative inclination, and in an another case the Permian red beds were corrected - using the TK03.GAD model - to a position at the latitude of the Netherlands, in contrast to their assumed paleo-equatorial position. We discuss the various merits of these different and independent methods for inclination error correction in these (and other) red bed sequences.

de Groot, L. V.; Haldan, M. M.; Langereis, C. G.

2007-12-01

20

Electrokinetic injection of ammonium and sulfate ions into sand and kaolinite beds  

SciTech Connect

Electrokinetic remediation is an emerging in-situ remediation technique that employs a low-level direct current (DC) across an electrode system inserted in soil to extract inorganic/organic species. The efficiency of electrokinetic injection of a cation (ammonium) from the anode and an anion (sulfate) from the cathode into a fine-grained sand bed and a kaolinite bed is investigated. Electrodes are placed in chambers across 80 cm of soil beds in a flume. The electrical conductivity of the kaolinite bed was 124.1 {+-} 6.6 {micro}S/cm approximately an order of magnitude higher than the fine sand bed while the hydraulic conductivity of the same was 2 {times} 10{sup {minus}7} cm/s about three orders of magnitude lower than the fine-grained sand bed. The electrical gradients of 1 V/cm or less constituted the predominant driving force for transport under constant current densities of 15 {micro}A/cm{sup 2} and 123 {micro}A/cm{sup 2} in the sand and kaolinite beds, respectively. An electrolyte conditioning scheme where the co-ions (hydroxide ion in the ammonium hydroxide used at the anode and the hydronium ion in the sulfuric acid used at the cathode) depolarized the electrode reactions maintained the pH value across the beds between 6.5 and 7.4. This novel conditioning scheme prevented formation and introduction of species formed by the electrode reactions and avoided unnecessary increase in the electrical conductivity in the electrolytes. Transport rates on the order of 8--20 cm/d were achieved for sulfate and ammonium ions in both the fine-grained sand bed and the kaolinite bed.

Acar, Y.B.; Rabbi, M.F.; Ozsu, E.E. [Louisiana State Univ., Baton Rouge, LA (United States)

1997-03-01

21

Experiments on the Evolution of Sand Bed Forms for Varying Degrees of Supply Limitation  

NASA Astrophysics Data System (ADS)

The advanced age and impending decommissioning of many dams have brought increased attention to the fate of sediments stored in reservoirs. In many cases, fine sediments are reintroduced to coarse substrates that have large volumes of pore space available for storage after having sediments removed by years of sediment-starved flow. Recent research has found that the fine sediment elevation relative to the coarse substrate significantly alters bed surface roughness, turbulence characteristics, the mobility of the fine sediment, and consequently sediment transport rates and sediment bed forms that move over and through these coarse substrates. The roughness of the bed surface is an important parameter for the prediction of bulk flow and sediment transport rates. In order to calculate sediment transport rates, bed shear stresses are typically adjusted for drag exerted by the flow on macro roughness elements, which are related here to the protrusion of coarse substrate particles and sediment bed forms. Also, the partial mobility (or supply limitation) of sediment yields bed forms that differ from those observed for uniform bed material. Hence, a proper understanding of the interactions between near-bed flow structure, sediment transport rates, and bed surface elevation is needed to adequately determine the downstream impact of fine sediment releases from reservoirs. Recent experiments at the USDA-ARS-National Sedimentation Laboratory in a sediment-recirculating flume (15 m long, 0.36 m wide, and 0.45 m deep) were carried out to elucidate turbulence and sand transport over and through coarse gravel substrates. The median diameter of the sand was 0.3 mm, and that of the gravel was 35 mm. This paper presents results on the change in bed form types with increasing sand elevation relative to the coarse gravel substrate and for Froude numbers ranging from about 0.1 to 0.6. The mean sand elevation was varied between 5 cm below the top of the gravel and the top of the gravel. The bed level was measured using both an acoustic sensor and stereo photogrammetry. The acoustic sensor provided bed elevation transects along the channel centerline, whereas digital elevation models with a horizontal grid size of 0.25x0.25 mm were derived from the stereo images. At low mean sand elevations an individual, low-relief dune-like bed form initially developed for larger Froude numbers. Groups of increasingly numerous low-relief bed forms developed when increasing mean sand elevation. The tops of the bed forms were located at an elevation similar to those of the higher gravel tops.

Langendoen, E. J.; Wren, D. G.; Kuhnle, R. A.

2011-12-01

22

Ichnology of the Cretaceous Oceanic Red Beds (Outer Western Carpathians, Czech Republic)  

NASA Astrophysics Data System (ADS)

Large differences in the intensity and overall character of bioturbational structures were found in five facies containing hemipelagic red beds. Red beds (CORB) of the Godula facies of the Silesian Unit and their equivalents (mostly not red) in the Kel? facies of the Silesian Unit and the CORB in the non-calcareous sediments of the Ra?a Unit display a very low degree of bioturbation. The CORB facies of the Ra?a Unit, containing calcareous intercalations, displays a very high degree of bioturbation as expressed by a high ichnofabric index. They contain trace fossils Chondrites, Zoophycos, Planolites, Thalassinoides, Palaeophycus, Teichichnus and Phycosiphon. The supply of food obviously acted as the controlling factor. The "calcareous" facies of the CORB of the Ra?a Unit has a considerably higher proportion of sand-dominated interbeds and also carbonates than the non-calcareous facies. This (especially the presence of carbonates) suggests a relative proximity of food-rich environments and an easy transport of nutrition-rich substrate by turbidite currents into the basin directly, not only by periodical fall-out of dead plankton (which is probably responsible for the rhythmicity of poor colonization horizons in weakly bioturbated units).

Mikuláš, Radek; Skupien, Petr; Bubík, Miroslav; Vaší?ek, Zden?k

2009-06-01

23

Evaluation and Comparison of Red Fork Sand Waterflood Projects in Oklahoma.  

National Technical Information Service (NTIS)

Information on oil and water production, volume of water injected, core analyses, and well completion data was collected on 28 Red Fork sand waterflood projects for comparison and evaluation of results. An average water injection efficiency of 35 percent,...

K. H. Johnston

1970-01-01

24

Filtration of Activated Sludge Secondary Effluents Through Sand and Anthracite-Sand Beds.  

National Technical Information Service (NTIS)

Laboratory filtration studies were conducted on treated sewage effluent from a pilot activated sludge plant operated to provide effluent and mixed liquid solids for use in the experiments. The filtration media used were sand and a combination of anthracit...

Y. Misaka, L. B. Polkowski

1969-01-01

25

Colorado River sediment transport: 2. Systematic bed-elevation and grain-size effects of sand supply limitation  

Microsoft Academic Search

The Colorado River in Marble and Grand Canyons displays evidence of annual supply limitation with respect to sand both prior to [Topping et al., this issue] and after the closure of Glen Canyon Dam in 1963. Systematic changes in bed elevation and systematic coupled changes in suspended-sand concentration and grain size result from this supply limitation. During floods, sand supply

David J. Topping; Ingrid C. Corson

2000-01-01

26

Mathematical model on grain-size distribution in suspension over sand-gravel bed  

NASA Astrophysics Data System (ADS)

Modeling on grain-size distribution in suspension over sand-gravel bed has been done.Stratification and hindered settling effect have been included.Effect of particle–particle interaction is included in the computed reference level.Effect of different probability is considered in the computed reference concentration.The proposed model is verified with existing experimental data.

Pal, Debasish; Ghoshal, Koeli

2014-04-01

27

Longitudinal variability in hydraulic geometry and substrate characteristics of a Great Plains sand-bed river  

NASA Astrophysics Data System (ADS)

Downstream trends in hydraulic geometry and substrate characteristics were investigated along a 200 km reach of the Ninnescah River in south central Kansas, USA. The Ninnescah River is a large sand-bed, perennial, braided river located in the Central Plains physiographic province and is a tributary of the Arkansas River. Hydraulic geometry characteristics were measured at eleven reaches and included slope, sinuosity, bankfull channel width, and bankfull channel depth. Results indicated that the Ninnescah River followed a predicted trend of decreasing slope and increasing depth and width downstream. There were localized divergences in the central tendency, most notability downstream of a substantial tributary that is impounded and at the end of the surveying reach where the Ninnescah River approaches the Arkansas River. Surface grain-size samples were taken from the top 10 cm of the bed at five points across the wetted cross-section within each of the 11 reaches. Sediment analyses demonstrated a significant trend in downstream fining of surface grain-sizes (D90 and D50) but unlike previous studies of sand-bedded rivers we observed coarsening of substrates downstream of the major tributary confluence. We propose that the overall low discharge from the tributary was the primary reason for coarsening of the bed downstream of the tributary. Results of this study provide valuable baseline information that can provide insight in to how Great Plains sand-bed systems may be conserved, managed, and restored in the future.

Costigan, Katie H.; Daniels, Melinda D.; Perkin, Joshuah S.; Gido, Keith B.

2014-04-01

28

Chemical remanent magnetization of red beds and synthetic hematite  

SciTech Connect

Magnetic minerals produced during diagenesis add one or more components of chemical remanence to the new magnetization of the rock. The magnetic signature of chemically magnetized rocks may thus differ from the orientation of the Earth's magnetic field at the time of sediment deposition. Interpretation of paleomagnetic data obtained from chemically magnetized sediments requires an understanding of the way in which magnetic minerals record the orientation and intensity of the magnetic field applied during their growth and the reliability with which successive generations of these minerals grown in different applied field orientations record those fields. To understand the properties of chemical remanence produced during the growth of one or more generations of hematite, the authors precipitated hematite in known conditions of the applied magnetic field. Hysteresis properties, scanning electron microscopy, and thermogravimetric analysis demonstrate that the synthetic material is analogous to pigmentary hematite present in the Siwalik red beds of northern Pakistan; thermal demagnetization and isothermal remanence acquisition behavior of both are also similar. Hematite precipitated in a single episode parallels the growth field, and preliminary work suggests a linear relationship between the field intensity applied during precipitation and the mineral's remanent intensity. The directional properties of hematite produced in successive generations are far more complex and argue for careful assessment of the reliability of paleomagnetic data from red beds. They show that the magnetic fabric analysis is useful in this evaluation.

Stokking, L.B. (Texas A and M Univ., College State (United States)); Tauxe, L. (Scripps Institution of Oceanography, La Jolla, CA (United States))

1991-03-01

29

Colorado River sediment transport 2. Systematic bed-elevation and grain-size effects of sand supply limitation  

USGS Publications Warehouse

The Colorado River in Marble and Grand Canyons displays evidence of annual supply limitation with respect to sand both prior to [Topping et al., this issue] and after the closure of Glen Canyon Dam in 1963. Systematic changes in bed elevation and systematic coupled changes in suspended-sand concentration and grain size result from this supply limitation. During floods, sand supply limitation either causes or modifies a lag between the time of maximum discharge and the time of either maximum or minimum (depending on reach geometry) bed elevation. If, at a cross section where the bed aggrades with increasing flow, the maximum bed elevation is observed to lead the peak or the receding limb of a flood, then this observed response of the bed is due to sand supply limitation. Sand supply limitation also leads to the systematic evolution of sand grain size (both on the bed and in suspension) in the Colorado River. Sand input during a tributary flood travels down the Colorado River as an elongating sediment wave, with the finest sizes (because of their lower settling velocities) traveling the fastest. As the fine front of a sediment wave arrives at a given location, the bed fines and suspended-sand concentrations increase in response to the enhanced upstream supply of finer sand. Then, as the front of the sediment wave passes that location, the bed is winnowed and suspended-sand concentrations decrease in response to the depletion of the upstream supply of finer sand. The grain-size effects of depletion of the upstream sand supply are most obvious during periods of higher dam releases (e.g, the 1996 flood experiment and the 1997 test flow). Because of substantial changes in the grain-size distribution of the bed, stable relationships between the discharge of water and sand-transport rates (i.e., stable sand rating curves) are precluded. Sand budgets in a supply-limited river like the Colorado River can only be constructed through inclusion of the physical processes that couple changes in bed-sediment grain size to changes in sand-transport rates.

Topping, D. J.; Rubin, D. M.; Nelson, J. M.; Kinzel, III, P. J.; Corson, I. C.

2000-01-01

30

Bed load and suspended load contributions to migrating sand dunes in equilibrium  

NASA Astrophysics Data System (ADS)

dominate the bed of sand rivers and are of central importance in predicting flow roughness and water levels. The present study has focused on the details of flow and sediment dynamics along migrating sand dunes in equilibrium. Using a recently developed acoustic system (Acoustic Concentration and Velocity Profiler), new insights are obtained in the behavior of the bed and the suspended load transport along mobile dunes. Our data have illustrated that, due to the presence of a dense sediment layer close to the bed and migrating secondary bedforms over the stoss side of the dune toward the dune crest, the near-bed flow and sediment processes are significantly different from the near-bed flow and sediment dynamics measured over fixed dunes. It was observed that the shape of the total sediment transport distribution along dunes is mainly dominated by the bed load transport, although the bed load and the suspended load transport are of the same order of magnitude. This means that it was especially the bed load transport that is responsible for the continuous erosion and deposition of sediment along the migrating dunes. Whereas the bed load is entirely captured in the dune with zero transport at the flow reattachment point, a significant part of the suspended load is advected to the downstream dune depending on the flow conditions. For the two flow conditions measured, the bypass fraction was about 10% for flow with a Froude number (Fr) of 0.41 and 27% for flow with Froude number of 0.51. This means that respectively 90% (for the Fr = 0.41 flow) and 73% (for the Fr = 0.51 flow) of the total sediment load that arrived at the dune crests contributed to the migration of the dunes.

Naqshband, S.; Ribberink, J. S.; Hurther, D.; Hulscher, S. J. M. H.

2014-05-01

31

Development of an inclined liquid fluidized bed for tar sand processing  

SciTech Connect

An inclined liquid fluidized-bed reactor (ILFBR) system has been developed and successfully operated for 24 hours. Modifications to the previously tested ILFBR systems include incorporation of a oil fluidizing zone in the front of the fluid bed, an increase in the angle of the fluid bed to {minus}12{degree} (the minus sign shows that the discharges is below the horizontal level of the inlet), and reduction of the fluidizing gas velocities equal to or below the minimum fluidization velocity. These changes produced a functional bubbling slurry bed for the processing of tar sand. The produced oils and spent sand resemble the products from screw pyrolysis reactor (SPR) tests suggesting that the ILFBR system functioned similar to the SPR systems with the recycle oil pyrolysis and extraction (ROPE{copyright}) process. With slight modifications in the heater control and placement, the system will be ready for development of operational parameters for the surface processing of tar sand. 10 refs., 2 figs., 1 tab.

Johnson, L.A. Jr.

1989-12-01

32

A new sampler for extracting bed material sediment from sand and gravel beds in navigable rivers  

Microsoft Academic Search

Grain-size distributions of bed material sediment in large alluvial rivers are required in various scientific and management applications, but characterizing gravel beds in navigable rivers is hampered by difficulties in sediment extraction. The newly developed and preliminarily tested sampler reported here can extract sediment from a range of riverbeds. The 36 × × × × × 23 × × ×

Michael Bliss Singer

2008-01-01

33

Aeolian Sand Transport in the Planetary Context: Respective Roles of Aerodynamic and Bed-Dilatancy Thresholds  

NASA Technical Reports Server (NTRS)

The traditional view of aeolian sand transport generally estimates flux from the perspective of aerodynamic forces creating the airborne grain population, although it has been recognized that "reptation" causes a significant part of the total airborne flux; reptation involves both ballistic injection of grains into the air stream by the impact of saltating grains as well as the "nudging" of surface grains into a creeping motion. Whilst aerodynamic forces may initiate sand motion, it is proposed here that within a fully-matured grain cloud, flux is actually governed by two thresholds: an aerodynamic threshold, and a bed-dilatancy threshold. It is the latter which controls the reptation population, and its significance increases proportionally with transport energy. Because we only have experience with terrestrial sand transport, extrapolations of aeolian theory to Mars and Venus have adjusted only the aerodynamic factor, taking gravitational forces and atmospheric density as the prime variables in the aerodynamic equations, but neglecting reptation. The basis for our perspective on the importance of reptation and bed dilatancy is a set of experiments that were designed to simulate sand transport across the surface of a martian dune. Using a modified sporting crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism, individual grains of sand were fired at loose sand targets with glancing angles typical of saltation impact; grains were projected at about 80 m/s to simulate velocities commensurate with those predicted for extreme martian aeolian conditions. The sabot impelling method permitted study of individual impacts without the masking effect of bed mobilization encountered in wind-tunnel studies. At these martian impact velocities, grains produced small craters formed by the ejection of several hundred grains from the bed. Unexpectedly, the craters were not elongated, despite glancing impact; the craters were very close to circular in planform. High-speed photography showed them to grow in both diameter and depth after the impactor had ricochetted from the crater site. The delayed response of the bed was "explosive" in nature, and created a miniature ejecta curtain spreading upward and outward for many centimeters for impact of 100-300 micron-diameter grains into similar material. Elastic energy deposited in the bed by the impacting grain creates a subsurface stress regime or "quasi-Boussinesq" compression field. Elastic recovery of the bed occurs by dilatancy; shear stresses suddenly convert the grains from closed to open packing, and grains are consequently able to eject themselves forcefully from the impact site. Random jostling of the grains causes radial homogenization of stress vectors and a resulting circular crater. There is a great temptation to draw parallels with cratering produced by meteorite impacts, but a rigorous search for common modelling ground between the two phenomena has not been conducted at this time. For every impact of an aerodynamically energized grain, there are several hundred grains ejected into the wind for the high-energy transport that might occur on Mars. Many of these grains will themselves become subject to the boundary layer's aerodynamic lift forces (their motion will not immediately die and add to the creep population), and these grains will become indistinguishable from those lifted entirely by aerodynamic forces. As each grain impacts the bed, it will eject even more grains into the flow. A cascading effect will take place, but because it must be finite in its growth, damping will occur as the number of grains set in motion causes mid-air collisions that prevent much of the impact energy from reaching the surface of the bed -thus creating a dynamic equilibrium in a high-density saltation cloud. It is apparent that for a given impact energy, the stress field permits a smaller volume of grains to convert to open packing as the size of the bed grains increases, or as the energy of the "percussive" grain decreases

Marshall, J. R.; Borucki, J.; Bratton, C.

1999-01-01

34

Aeolian Sand Transport in the Planetary Context: Respective Roles of Aerodynamic and Bed-Dilatancy Thresholds  

NASA Astrophysics Data System (ADS)

The traditional view of aeolian sand transport generally estimates flux from the perspective of aerodynamic forces creating the airborne grain population, although it has been recognized that "reptation" causes a significant part of the total airborne flux; reptation involves both ballistic injection of grains into the air stream by the impact of saltating grains as well as the "nudging" of surface grains into a creeping motion. Whilst aerodynamic forces may initiate sand motion, it is proposed here that within a fully-matured grain cloud, flux is actually governed by two thresholds: an aerodynamic threshold, and a bed-dilatancy threshold. It is the latter which controls the reptation population, and its significance increases proportionally with transport energy. Because we only have experience with terrestrial sand transport, extrapolations of aeolian theory to Mars and Venus have adjusted only the aerodynamic factor, taking gravitational forces and atmospheric density as the prime variables in the aerodynamic equations, but neglecting reptation. The basis for our perspective on the importance of reptation and bed dilatancy is a set of experiments that were designed to simulate sand transport across the surface of a martian dune. Using a modified sporting crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism, individual grains of sand were fired at loose sand targets with glancing angles typical of saltation impact; grains were projected at about 80 m/s to simulate velocities commensurate with those predicted for extreme martian aeolian conditions. The sabot impelling method permitted study of individual impacts without the masking effect of bed mobilization encountered in wind-tunnel studies. At these martian impact velocities, grains produced small craters formed by the ejection of several hundred grains from the bed. Unexpectedly, the craters were not elongated, despite glancing impact; the craters were very close to circular in planform. High-speed photography showed them to grow in both diameter and depth after the impactor had ricochetted from the crater site. The delayed response of the bed was "explosive" in nature, and created a miniature ejecta curtain spreading upward and outward for many centimeters for impact of 100-300 micron-diameter grains into similar material. Elastic energy deposited in the bed by the impacting grain creates a subsurface stress regime or "quasi-Boussinesq" compression field. Elastic recovery of the bed occurs by dilatancy; shear stresses suddenly convert the grains from closed to open packing, and grains are consequently able to eject themselves forcefully from the impact site. Random jostling of the grains causes radial homogenization of stress vectors and a resulting circular crater. There is a great temptation to draw parallels with cratering produced by meteorite impacts, but a rigorous search for common modelling ground between the two phenomena has not been conducted at this time. For every impact of an aerodynamically energized grain, there are several hundred grains ejected into the wind for the high-energy transport that might occur on Mars. Many of these grains will themselves become subject to the boundary layer's aerodynamic lift forces (their motion will not immediately die and add to the creep population), and these grains will become indistinguishable from those lifted entirely by aerodynamic forces. As each grain impacts the bed, it will eject even more grains into the flow. A cascading effect will take place, but because it must be finite in its growth, damping will occur as the number of grains set in motion causes mid-air collisions that prevent much of the impact energy from reaching the surface of the bed -thus creating a dynamic equilibrium in a high-density saltation cloud. It is apparent that for a given impact energy, the stress field permits a smaller volume of grains to convert to open packing as the size of the bed grains increases, or as the energy of the "percussive" grain decreases

Marshall, J. R.; Borucki, J.; Bratton, C.

1999-09-01

35

Sludge dewatering by sand-drying bed coupled with electrodewatering at various potentials  

Microsoft Academic Search

Large amounts of water in sludge from wastewater treatment plants directly translate into high transport and handling costs. In this study, a laboratory scale sludge sand-drying bed was coupled with an electro-dewatering process to investigate the trends of dewatering at variable voltage potentials. There was a two-fold increase of dry solid (DS) content in final sludge cake when the applied

A. T. Pham; M. Sillanpää; J. Virkutyte

2010-01-01

36

Characterisation of sand transport in gravel-bed rivers using iron slag dated by historical studies  

NASA Astrophysics Data System (ADS)

Considerable quantities of iron-smelting slag are present in the bed of the Ardennian rivers. These waste products come from hundreds of ironworks (mainly blast furnaces and finery forges) built close to different-sized rivers between the 14th and the 19th centuries. In general, slag was crushed by hammers, sorted and piled up in heaps around the furnaces, generally onto the floodplains. Furthermore, some archives mention that they were sometimes thrown out directly into the rivers. This means that for centuries, slag elements have been swept away by floods, mixed with the sediment and spread out along river courses. Due to their distinctive appearance, slag particles are easily recognizable among the natural elements. Thanks to many historical studies conducted on the early iron industry, we are able to date quite precisely the inception and the periods of activity of the different sites established in the catchments. These data are indispensable in order to use slag as a tracer to quantify the particles' velocity in rivers. Downstream of ironworks, samples of sand have been collected in the surface layer of many gravel-bed rivers. Then, the slag concentration of each sample has been measured in the coarse sand fraction. The representation of the longitudinal evolution of slag concentration in these rivers permits the dispersion of slag to be analysed, the relative bed-material discharges at confluences to be quantified and the velocity of coarse sand to be determined. A survey of the bedload discharge in the Ardennian rivers established that more than 90 % of the bedload transport consists of coarse sand grains that are transported on the bottom of the bed. However, in the literature, this grain-size fraction is generally not considered in bedload discharge estimations because the sandy particles are very difficult to tag and to recover. Consequently, the huge amounts of slag injected in rivers several centuries ago can be considered as a very useful opportunity to characterise the sand transport in gravel-bed rivers.

Houbrechts, G.; Levecq, Y.; Petit, F.

2012-04-01

37

Interactions between riparian vegetation and river morphodynamics in a sand-bed meandering stream.  

NASA Astrophysics Data System (ADS)

River morphodynamics results from the action of various sediment fluxes associated with different transport mechanisms, and those fluxes are influenced by the presence of riparian vegetation. We present in this study a comprehensive set of flow and sediment measurements required to compute the fluxes in a sand-bed stream with riparian vegetation. We collected data in a reduced-scale, movable-bed laboratory model of a reach that is undergoing rehabilitation using in-stream riparian vegetation. We used light weight sediment in order to ensure similar sediment mobility levels in model and prototype. Laboratory measurements included downstream and transverse velocities, bed shear stresses, bed load transport, suspended sediment concentrations, and bed topography over time with and without riparian vegetation placed along the outer bank of the bend. The results unveiled the importance of secondary circulation as well as converging and diverging flow patterns in shaping the bed topography. Modifications due to the vegetation included a shift of the main flow away from the vegetated outer bank and an overall straightening of the flow in the reach, resulting in an increased deposition near the vegetated bank and a reduced deposition near the inner bank. Our results highlight the need for overall reach assessment of flow and sediment dynamics before revegetation, as its effects go beyond local bank protection. We discuss implications for reach-scale morphodynamic modelling.

Gorrick, Sam; Rodriguez, Jose F.

2014-05-01

38

Evaluation of an experimental LiDAR for surveying a shallow, braided, sand-bedded river  

USGS Publications Warehouse

Reaches of a shallow (<1.0m), braided, sand-bedded river were surveyed in 2002 and 2005 with the National Aeronautics and Space Administration's Experimental Advanced Airborne Research LiDAR (EAARL) and concurrently with conventional survey-grade, real-time kinematic, global positioning system technology. The laser pulses transmitted by the EAARL instrument and the return backscatter waveforms from exposed sand and submerged sand targets in the river were completely digitized and stored for postflight processing. The vertical mapping accuracy of the EAARL was evaluated by comparing the ellipsoidal heights computed from ranging measurements made using an EAARL terrestrial algorithm to nearby (<0.5m apart) ground-truth ellipsoidal heights. After correcting for apparent systematic bias in the surveys, the root mean square error of these heights with the terrestrial algorithm in the 2002 survey was 0.11m for the 26 measurements taken on exposed sand and 0.18m for the 59 measurements taken on submerged sand. In the 2005 survey, the root mean square error was 0.18m for 92 measurements taken on exposed sand and 0.24m for 434 measurements on submerged sand. In submerged areas the waveforms were complicated by reflections from the surface, water column entrained turbidity, and potentially the riverbed. When applied to these waveforms, especially in depths greater than 0.4m, the terrestrial algorithm calculated the range above the riverbed. A bathymetric algorithm has been developed to approximate the position of the riverbed in these convolved waveforms and preliminary results are encouraging. ?? 2007 ASCE.

Kinzel, P. J.; Wright, C. W.; Nelson, J. M.; Burman, A. R.

2007-01-01

39

Petrophysical and textural characteristics of thin-bedded turbidite sands, Miocene Mt. Messenger formation, Taranaki Peninsula, New Zealand  

SciTech Connect

The Mt. Messenger Formation exposed along the Taranaki coastline (North Island) and in nearby producing oil fields is 600 meters thick and consists of a turbidite sequence deposited in a foredeep trough adjacent to a relatively narrow shelf in lower to upper bathyal water depths. Gamma-ray values of {open_quote}Thick-bedded{close_quote} sands greater than 15 cm thick on the outcrop are less than 175 counts per second (cps). These sandstones have the highest permeability values (100-800 mD). {open_quote}Thin-bedded{close_quotes} sands (5-15 cm) have values greater than 175 cps and range from 200-600 mD. {open_quote}Very Thin-bedded{close_quote} sands (less than 5 cm) range from 10-200 mD; gamma-ray values are impossible to resolve on the outcrop. Gamma-ray values in claystones exceed 250 cps. Lower very fine to silty sands (upper part of sequence) have significantly lower permeabilities because of sorting and the presence of mica and clay. A typical cored section through a pay interval consists of an upper 10-meter interval with average pay thickness of 17.5 cm (44% of the beds are greater than 20 cm thick and permeabilities average 144 mD) and a lower 20 m thick interval containing thinner pay sands (average 12.5 cm and only 22% of the beds are greater than 20 cm thick). Permeabilities average 130 mD. Thirty-seven percent of the interval contains pay sand and the remainder is claystones or non-pay sand. Interbedded thin-bedded water and oil-bearing sands have similar permeabilities and capillary properties. Clean, wet sands have less clay or feldspar and a lower gamma ray count than sands containing oil. The cause for wet sands interbedded with oil sands in the subsurface appears to be isolation and early sealing (microcompartmentalization) of sands by claystones. These features are observed in the coastal exposures.

Douglas, J.W. [ARCO International Oil and Gas Company, Plano, TX (United States); King, P.R.; Browne, G.H. [Institute of Geological and Nuclear Science, Lower Hutt (New Zealand)

1995-08-01

40

Application of magnetic susceptibility for correlation of the Lower Triassic red beds of the Baltic basin  

Microsoft Academic Search

Katinas V., Nawrocki J. Application of magnetic susceptibility for correlation of the Lower Triassic red beds of the Baltic basin. Geologija. Vilnius, 2006. No 56. P. 53-59. ISSN 1392-110X Correlation of red beds by magnetic susceptibility is a new and cheap research method in Lithuania. Lower Triassic samples were collected from three boreholes of Lithuania and one well of Kaliningrad

Valentas Katinas; Jerzy Nawrocki

41

Suspension of bed material over sand bars in the Lower Mississippi River and its implications for Mississippi delta environmental restoration  

NASA Astrophysics Data System (ADS)

specific pathways for sand transport in the lower reaches of large rivers, including the Mississippi, is a key for addressing multiple significant geologic problems, such as delta building and discharge to the oceans, and for environmental restoration efforts in deltaic environments threatened by rising sea levels. Field studies were performed in the Mississippi River 75-100 km upstream of the Gulf of Mexico outlet in 2010-2011 to examine sand transport phenomena in the tidally affected river channel over a range of discharges. Methods included mapping bottom morphology (multibeam sonar), cross-sectional and longitudinal measurements of water column velocity and acoustic backscatter, suspended sediment sampling, and channel-bed sampling. Substantial interaction was observed between the flow conditions in the river (boundary shear stress), channel-bed morphology (size and extent of sandy bedforms), and bed material sand transport (quantity, transport mode, and spatial distribution). A lateral shift was observed in the region of maximum bed material transport from deep to shallow areas of subaqueous sand bars with increasing water discharge. Bed material was transported both in traction and in suspension at these water discharges, and we posit that the downriver flux of sand grains is composed of both locally- and drainage basin-sourced material, with distinct transport pathways and relations to flow conditions. We provide suggestions for the optimal design and operation of planned river diversion projects.

Ramirez, Michael T.; Allison, Mead A.

2013-06-01

42

Validating Experimental Bedform Dynamics on Cohesive Sand-Mud Beds in the Dee Estuary  

NASA Astrophysics Data System (ADS)

Recent laboratory experiments and field measurements have shown that small quantities of cohesive clay, and in particular 'sticky' biological polymers, within a sandy substrate dramatically reduce the development rate of sedimentary bedforms, with major implications for sediment transport rate calculations and process interpretations from the sedimentary record. FURTHER INFORMATION Flow and sediment transport predictions from sedimentary structures found in modern estuaries and within estuarine geological systems are impeded by an almost complete lack of process-based knowledge of the behaviour of natural sediments that consist of mixtures of cohesionless sand and biologically-active cohesive mud. Indeed, existing predictive models are largely based on non-organic cohesionless sands, despite the fact that mud, in pure form or mixed with sand, is the most common sediment on Earth and also the most biologically active interface across a range of Earth-surface environments, including rivers and shallow seas. The multidisciplinary COHBED project uses state-of-the-art laboratory and field technologies to measure the erosional properties of mixed cohesive sediment beds and the formation and stability of sedimentary bedforms on these beds, integrating the key physical and biological processes that govern bed evolution. The development of current ripples on cohesive mixed sediment beds was investigated as a function of physical control on bed cohesion versus biological control on bed cohesion. These investigations included laboratory flume experiments in the Hydrodynamics Laboratory (Bangor University) and field experiments in the Dee estuary (at West Kirby near Liverpool). The flume experiments showed that winnowing of fine-grained cohesive sediment, including biological stabilisers, is an important process affecting the development rate, size and shape of the cohesive bedforms. The ripples developed progressively slower as the kaolin clay fraction in the sandy substrate bed was increased. The same result was obtained for xanthan gum, which is a proxy for biological polymers produced by microphytobenthos. Yet, the xanthan gum was several orders more effective in slowing down ripple development than kaolin clay, suggesting that the cohesive forces for biological polymers are much higher than for clay minerals, and that sedimentological process models should refocus on biostabilisation processes. The first results of the field experiments show that the winnowing of fines from developing ripples and the slowing down of current ripple development in mixed cohesive sediment is mimicked on intertidal flats in the Dee estuary. In particular, these field data revealed that current ripples in cohesive sediment are smaller with more two-dimensional crestlines than in non-cohesive sand. The wider implications of these findings will be discussed. COHBED Project Team (NERC): Alan Davies (Bangor University); Daniel Parsons, Leiping Ye (University of Hull); Jeffrey Peakall (University of Leeds); Dougal Lichtman, Louise O'Boyle, Peter Thorne (NOC Liverpool); Sarah Bass, Andrew Manning, Robert Schindler (University of Plymouth); Rebecca Aspden, Emma Defew, Julie Hope, David Paterson (University of St Andrews)

Baas, Jaco H.; Baker, Megan; Hope, Julie; Malarkey, Jonathan; Rocha, Renata

2014-05-01

43

Numerical simulation of widening and bed deformation of straight sand-bed rivers. II: Model evaluation  

USGS Publications Warehouse

In this paper the numerical model presented in the companion paper is tested and applied. Assessment of model accuracy was based on two approaches. First, predictions of evolution of a 13.5 km reach of the South Fork of the Forked Deer River, in west Tennessee, were compared to observations over a 24-yr period. Results suggest that although the model was able to qualitatively predict trends of widening and deepening, quantitative predictions were not reliable. Simulated widths and depths were within 15% of the corresponding observed values, but observed change in these parameters at the study sites were also close to these values. Simulated rates of depth adjustment were within 15% of observed rates, but observed rates of channel widening at the study sites were approximately three times those simulated by the model. In the second approach, the model was used to generate relationships between stable channel width and bank-full discharge. The model was able to successfully replicate the form of empirically derived regime-width equations. Simulations were used to demonstrate the model's ability to obtain more realistic predictions of bed evolution in widening channels.

Darby, S. E.; Thorne, C. R.; Simon, A.

1996-01-01

44

Hydro-morphological analysis of a sand-bed river in Hungary  

NASA Astrophysics Data System (ADS)

The main goal of this paper is to introduce a suitable procedure for the assessment of reach-scale hydro-morphological conditions of rivers. For this purpose a 4 km long reach of River Tisza in Hungary was chosen and investigated by means of comprehensive field measurements and three-dimensional numerical modelling. The river can be characterized with an average depth of 6 m and an average width of 150 m, whereas the mean annual discharge is around 800 m3/s. The bed material is sand with a d50 of 0.2 mm. In the shallow zones of the river bed forms are migrating with a typical length of 20 m and amplitude of 0.3 m. The study reach has recently been surveyed in 2008 and 2010. The river bed evolution occurred during the two years is assessed by difference maps of the river bathymetry. Furthermore, moving and fixed ADCP measurements were carried out in order to reveal the spatial flow structure. Suspended sediment and bed material samples were also collected yielding the sediment discharge and characteristic grain size distributions. Moreover, the bed movement was also quantified in some locations of the reach based on the deviation between bottom track and GPS positions collected during fixed ADCP measurements. Parameterizing with the detailed field data a three-dimensional flow and sediment transport model was applied to carry out morphological simulations. The numerical model solves the Reynolds averaged Navier-Stokes equations (RANS) using a k-epsilon turbulence closure. The empirical formulas of van Rijn were used to estimate sediment concentration close to the bed. Moreover, the flow resistance due to bed forms was also considered using an empirical approach. A comparative analysis of the measured and simulated velocity field, sediment concentration and river bed migration was accomplished to introduce model capabilities. Furthermore, three-dimensional flow structure accounting for the development of local, unique morphological features is analysed. The coupled field and numerical investigations can greatly contribute to the establishment of the sediment budget for the study reach, however, further research is needed, e.g. analysis of high water regimes or the study of long term changes in the sediment transport and river morphology.

Baranya, S.; Rajmund, S.; Józsa, J.

2012-04-01

45

Sand Transport and Turbulence over Immobile Gravel and Cobble Beds: Similarities and Differences Caused by Roughness Scale  

NASA Astrophysics Data System (ADS)

Characterizing the turbulence generated by flow over rough beds has become increasingly important in support of efforts to predict sediment transport downstream of dams. The advanced age and impending decommissioning of many dams have brought increased attention to the fate of sediments stored in reservoirs. In many cases, fine sediments are reintroduced to coarse substrates that have large volumes of pore space available for storage after having sediments removed by years of sediment-starved flow. The roughness and porosity of the coarse substrate are both affected by the fine sediment elevation relative to the coarse substrate; therefore, the turbulence characteristics and sediment transport over and through these beds are significantly altered after sediment is reintroduced. Experiments at the USDA-ARS-National Sedimentation Laboratory have focused on sand transport and turbulence over two different rough, immobile, substrates: 35 mm gravel and 150 mm cobbles. Detailed acoustic Doppler-based measurements of turbulence structure over the gravel and cobble beds have allowed the influence of the scale of roughness on both the turbulence and sand transport to be evaluated. It was found that the sand transport in both the gravel and cobble beds showed a strong relationship with bed shear stress scaled by the value of the cumulative distribution of bed elevation at the level of sand within the rough bed. Reynolds stresses near and just below the top of the cobble bed show a region of near constant value with depth, while, for the gravel bed there is a gradual decrease in Reynolds stress beginning just above the gravel and decreasing with increasing depth into the gravel. Dispersive stresses show a very similar patter with a peak at the top of the roughness elements decaying to zero with increasing distance above and below.

Wren, D. G.; Langendoen, E. J.; Kuhnle, R. A.

2011-12-01

46

Pyrite-haematite alteration as a source of colour in red beds and regolith  

Microsoft Academic Search

THE colour in red beds and red soils is generally acknowledged to be caused by the presence of finely dispersed haematite or hydro-haematite. The origin of the haematite remains, however, in dispute1-3. In the case of present-day red weathering in the tropics and subtropics, the haematite or other colouring material is obviously derived by in situ alteration of iron-bearing minerals

G. A. Challis

1975-01-01

47

Comparing particle-size distributions in modern and ancient sand-bed rivers  

NASA Astrophysics Data System (ADS)

Particle-size distributions yield valuable insight into processes controlling sediment supply, transport, and deposition in sedimentary systems. This is especially true in ancient deposits, where effects of changing boundary conditions and autogenic processes may be detected from deposited sediment. In order to improve interpretations in ancient deposits and constrain uncertainty associated with new methods for paleomorphodynamic reconstructions in ancient fluvial systems, we compare particle-size distributions in three active sand-bed rivers in central Nebraska (USA) to grain-size distributions from ancient sandy fluvial deposits. Within the modern rivers studied, particle-size distributions of active-layer, suspended-load, and slackwater deposits show consistent relationships despite some morphological and sediment-supply differences between the rivers. In particular, there is substantial and consistent overlap between bed-material and suspended-load distributions, and the coarsest material found in slackwater deposits is comparable to the coarse fraction of suspended-sediment samples. Proxy bed-load and slackwater-deposit samples from the Kayenta Formation (Lower Jurassic, Utah/Colorado, USA) show overlap similar to that seen in the modern rivers, suggesting that these deposits may be sampled for paleomorphodynamic reconstructions, including paleoslope estimation. We also compare grain-size distributions of channel, floodplain, and proximal-overbank deposits in the Willwood (Paleocene/Eocene, Bighorn Basin, Wyoming, USA), Wasatch (Paleocene/Eocene, Piceance Creek Basin, Colorado, USA), and Ferris (Cretaceous/Paleocene, Hanna Basin, Wyoming, USA) formations. Grain-size characteristics in these deposits reflect how suspended- and bed-load sediment is distributed across the floodplain during channel avulsion events. In order to constrain uncertainty inherent in such estimates, we evaluate uncertainty associated with sample collection, preparation, analytical particle-size analysis, and statistical characterization in both modern and ancient settings. We consider potential error contributions and evaluate the degree to which this uncertainty might be significant in modern sediment-transport studies and ancient paleomorphodynamic reconstructions.

Hajek, E. A.; Lynds, R. M.; Huzurbazar, S. V.

2011-12-01

48

Modelling intensive near-bed sand transport under wave–current flow versus laboratory and field data  

Microsoft Academic Search

The present study is focused on sand transport in combined wave–current flow (at any angle between them) in the intensive flow regime. The present model is based on the 1DV approximation. The mathematical method for the continuous description of processes from the immobile bed to the formation of sheet flow and suspended load is presented. The way of modelling of

Leszek M Kaczmarek; Rafa? Ostrowski

2002-01-01

49

Bedform development in mixed sand-mud: The contrasting role of cohesive forces in flow and bed  

NASA Astrophysics Data System (ADS)

The majority of subaqueous sediment on Earth consists of mixtures of cohesive clay and cohesionless sand and silt, but the role of cohesion on the development and stability of sedimentary bedforms is poorly understood. The results of new laboratory flume experiments on bedform development in cohesive, mixed sand-mud beds are compared with the results of previous experiments in which cohesive forces in high concentration clay flows dominated bedform development. Even though both series of mixed sand-mud experiments were conducted at similar flow velocities, the textural and structural properties of the bedforms were sufficiently different to permit the designation of key criteria for identifying bedform generation under cohesive flows against bedform generation on cohesive substrates. These criteria are essential for improving bedform size predictions in sediment transport modelling in modern sedimentary environments and for the reconstruction of depositional processes in the geological record. The current ripples developing on the cohesive, mixed sand-mud beds, with bed mud fractions of up to 18%, were significantly smaller than equivalent bedforms in noncohesive sand. Moreover, the bedform height showed a stronger inversely proportional relationship with initial bed mud fraction than the bedform wavelength. This is in contrast with the bedforms developing under the cohesive clay flows, which tend to increase in size with increasing suspended clay concentration until the flow turbulence is fully suppressed. Selective removal of clay from the mixed beds, i.e., clay winnowing, was found to be an important process, with 82-100% clay entrained into suspension after 2 h of bedform development. This winnowing process led to the development of a sand-rich armouring layer. This armouring layer is inferred to have protected the underlying mixed sand-mud from prolonged erosion, and in conjunction with strong cohesive forces in the bed may have caused the smaller size of the bedforms. Winnowing was less efficient for the bedforms developing under the cohesive clay flows, where bedforms consisting of muddy sand were more characteristic. The winnowed sand was also found to heal irregularly scoured topography, thus reestablishing classic quasitriangular bedform shapes. In cohesive flows, the bedforms had more variable shapes, and the healing process was confined to lower transitional plug flows in which strong turbulence is only present close to the sediment bed. Furthermore, the bedforms on the cohesive beds tended to form angle-of-repose cross lamination, whereas low angle cross lamination was more common in bedforms under cohesive flows. In general terms, erosional bedforms prevail when cohesive forces in the bed dominate bedform dynamics, whereas depositional bedforms prevail when cohesive forces in the flow dominate bedform dynamics. Empirical relationships between the proportion of cohesive mud in the mixed sand-mud bed and the development rate and size of the bedforms are defined for future use in field and laboratory studies.

Baas, Jaco H.; Davies, Alan G.; Malarkey, Jonathan

2013-01-01

50

Interactions among riparian vegetation, flow and sediment in a sand bed river: Implications for restoration  

NASA Astrophysics Data System (ADS)

We present a set of laboratory experiments based on field site conditions on a sand bed stream in Australia that is currently being restored by reintroduction of lost riparian vegetation. Three experiments were conducted in order to investigate both the local and reach-scale impacts of bank vegetation on flow and sediment dynamics. The first experiment contained no bank vegetation and was similar to the original state of the stream. The second experiment placed a series of three inline vegetation patches along the outer bank, simulating the design of the ongoing restoration works. The third experiment used a continuous strip of vegetation along the outer bank, which represents a more traditional restoration technique. In each experiment flow and sediment measurements were carried out, including ADV velocities, water surface elevations, suspended and bedload sediment transport rates and bed evolution. The analysis focussed on the quantification of flow and sediment fluxes and the resulting stream morphology, which responded to the presence of vegetation and to changes in stream curvature and width. Both arrangements of vegetation provided effective bank protection; however the patches used less vegetation and were thus more efficient. The reach-scale effects included changes to stream curvature, stream width and redistribution of sediments, all of which have important implications for management. Recommendations also include the selection of optimum patch size and spacing as well as plant composition.

Gorrick, S.; Rodriguez, J. F.

2012-12-01

51

Sand  

NSDL National Science Digital Library

This site provides an introduction to sand, a size fraction of what is commonly known as sediment (along with gravel, silt, and clay). An introductory section discusses the sedimentary aspects (grain size, rounding, and sorting), composition, and texture of sand. There is a virtual collection of sand specimens, sorted by location, region, or color. Each photo can be zoomed in or out and is accompanied by a brief description of the specimen. There is also a geographical index of specimens from the virtual collection which uses an interactive map to display them. An exercise is provided which uses specimens from the virtual collection to help students develop a connection between certain characteristics of sands and their environment of formation, information which can be applied to inferring the depositional environments of ancient sandstones. Other materials include a sand discovery kit, created to help teachers use sand in their classrooms, a 'Sands of the World' poster, and links to related websites. Some of these items must be purchased.

52

Development and design of a fluidized bed/upflow sand filter configuration for use in recirculating aquaculture systems  

SciTech Connect

A fluidized bed/upflow sand filter configuration, was developed and designed for utilization in recirculating aquaculture system, specifically the soft-shell crab and soft-shell crawfish industries. These filters were selected and designed because of their ability to withstand clogging and still maintain high levels of water quality for aquaculture production. The effectiveness of sand grain size was used to evaluate fluidized bed filter performance with filter loadings ranging from 16 to 1285 pounds of crawfish per cubic foot of filter sand. A coarse sand grain size was recommended as a filter media because of it's ability to shear excessive biofilm growth from the and, thus prohibiting clogging from occurring within the filter bed. The fluidized bed/upflow sand filter combination was evaluated in terms of nitrification and oxygen consumption when used with a recirculating crab shedding system. The filter combination's carrying capacity (700 crabs per cubic foot of sand media) exceeded that observed with the submerged rock filter by more than 20 times and was largely explained by the filter's solids removal ability which significantly reduced the filter's oxygen loading rate (OLR). Nitrification rates with the filter combination were extremely high as total ammonia and nitrite levels remained below 1.0 mg-N/l. Verification of a volumetric loading criteria (150 pounds per cubic foot) for this filter combination was further established with performance data obtained from a commercial soft-shell crawfish facility. Water quality monitoring results indicated that the filters maintained total ammonia and nitrite levels below 1.0 mg-N/l under typical operating conditions. Shock loading, pH control, and over-feeding, rather than filter capacity, dominated water quality fluctuations, thereby indicating that the loading criteria was sufficient for commercial operation.

Burden, D.G.

1988-01-01

53

The use of fluidized sand bed as an innovative technique for heat treating aluminum based castings  

NASA Astrophysics Data System (ADS)

The current study was carried out to arrive at a better understanding of the influences of the fluidized sand bed heat treatment on the tensile properties and quality indices of A356.2 and B319.2 casting alloys. For the purposes of validating the use of fluidized sand bed furnaces in industrial applications for heat treatment of 356 and 319 castings, the tensile properties and the quality indices of these alloys were correlated with the most common metallurgical parameters, such as strontium modification, grain refining, solutionizing time, aging parameters and quenching media. Traditional heat treatment technology, employing circulating air convection furnaces, was used to establish a relevant comparison with fluidized sand beds for the heat treatment of the alloys investigated, employing T6 continuous aging cycles or multi-temperature aging cycles. Quality charts were used to predict and/or select the best heat treatment conditions and techniques to be applied in industry in order to obtain the optimum properties required for particular engineering applications. The results revealed that the strength values achieved in T6-tempered 319 and 356 alloys are more responsive to fluidized bed (FB) heat treatment than to conventional convection furnace (CF) treatment for solution treatment times of up to 8 hours. Beyond this solution time, no noticeable difference in properties is observed with the two techniques. A significant increase in strength is observed in the FB heat-treated samples after short aging times of 0.5 and 1 hour, the trend continuing up to 5 hours. The 319 alloys show signs of overaging after 8 hours of aging using a conventional furnace, whereas with a fluidized bed, overaging occurs after 12 hours. Analysis of the tensile properties in terms of quality index charts showed that both modified and non-modified 319 and 356 alloys display the same, or better, quality, after only a 2-hr treatment in an FB compared to 10 hours when using a CF. The quality values of the 356 alloys are more responsive to the FB technique than 319 alloys through long aging times of up to 5 hours. The 319 alloys heat-treated in an FB, however, show better quality values after 0.5 hour of aging and for solution treatment times of up to 5 hours than those treated using a CF. With regard to the quality charts of 319 alloys, heat-treated samples show that increasing the aging time up to peak-strength, i.e. 8 and 12 hours in a CF and an FB, respectively, results in increasing in the alloy strength with a decrease in the quality values, for each of the solution heat treatment times used. The statistical analysis of the results reveals that modification and heating rate of the heat treatment technique have the greatest positive effects on the quality values of the 356 alloys. The use of a fluidized sand bed for the direct quenching-aging treatment of A356.2 and B319.2 casting alloys yields greater UTS and YS values compared to conventional furnace quenched alloys. The strength values of T6 tempered A356 and B319 alloys are greater when quenched in water compared to those quenched in an FB or CF. For the same aging conditions (170°C/4h), the fluidized bed quenched-aged 319 and 356 alloys show nearly the same or better strength values than those quenched in water and then aged in a CF or an FB. Based on the quality charts developed for alloys subjected to different quenching media, higher quality index values are obtained by water-quenched T6-tempered A356 alloys, and conventional furnace quenched-aged T6-tempered B319 alloys, respectively. The modification factor has the most significant effect on the quality results of the alloys investigated, for all heat treatment cycles, as compared to other metallurgical parameters. The results of alloys subjected to multi-temperature aging cycles reveal that the strength results obtained after the T6 continuous aging treatment of A356 alloys are not improved by means of multi-temperature aging cycles, indicating therefore that the optimum properties are obtained using a T6 aging treatment. The optimu

Ragab, Khaled

54

Scaling of Sediment Dynamics in a Reach-Scale Laboratory Model of a Sand-Bed Stream with Riparian Vegetation  

NASA Astrophysics Data System (ADS)

A movable bed physical model was designed in a laboratory flume to simulate both bed and suspended load transport in a mildly sinuous sand-bed stream. Model simulations investigated the impact of different vegetation arrangements along the outer bank to evaluate rehabilitation options. Preserving similitude in the 1:16 laboratory model was very important. In this presentation the scaling approach, as well as the successes and challenges of the strategy are outlined. Firstly a near-bankfull flow event was chosen for laboratory simulation. In nature, bankfull events at the field site deposit new in-channel features but cause only small amounts of bank erosion. Thus the fixed banks in the model were not a drastic simplification. Next, and as in other studies, the flow velocity and turbulence measurements were collected in separate fixed bed experiments. The scaling of flow in these experiments was simply maintained by matching the Froude number and roughness levels. The subsequent movable bed experiments were then conducted under similar hydrodynamic conditions. In nature, the sand-bed stream is fairly typical; in high flows most sediment transport occurs in suspension and migrating dunes cover the bed. To achieve similar dynamics in the model equivalent values of the dimensionless bed shear stress and the particle Reynolds number were important. Close values of the two dimensionless numbers were achieved with lightweight sediments (R=0.3) including coal and apricot pips with a particle size distribution similar to that of the field site. Overall the moveable bed experiments were able to replicate the dominant sediment dynamics present in the stream during a bankfull flow and yielded relevant information for the analysis of the effects of riparian vegetation. There was a potential conflict in the strategy, in that grain roughness was exaggerated with respect to nature. The advantage of this strategy is that although grain roughness is exaggerated, the similarity of bedforms and resulting drag can return similar levels of roughness to those in the field site.

Gorrick, S.; Rodriguez, J. F.

2011-12-01

55

Iron oxide mineralogy in late Miocene red beds from La Gloria, Spain: rock-magnetic, voltammetric and Vis spectroscopy analyses  

Microsoft Academic Search

Free ferric oxides of a red bed series were analyzed by rock-magnetic techniques (IRM component analysis) and by two less traditional methods: visible spectroscopy and voltammetry. All three methods have low limits of detection, making them suited for this type of analysis. The red bed samples studied contained clay minerals, quartz, and calcium carbonate as major constituents. Free Fe oxides

T. Grygar; J. D?de?ek; P. P. Kruiver; M. J. Dekkers; P. Bezdi?ka; O. Schneeweiss

2003-01-01

56

The mobility and distribution of heavy metals during the formation of first cycle red beds.  

USGS Publications Warehouse

Analysis of the heavy metal content in a Holocene-Pliocene red bed sequence near San Felipe in N Baja California, Mexico, has yielded new information on the mobility and distribution of these metals during ageing of iron oxyhydroxides from the amorphous to the crystalline state. Whole-rock samples (27) and a series of successive leachates were analysed for V, Al, Cr, Mn, Fe, Co, Ni, Cu and Zn by ICP spectrometry and for U by a delayed neutron technique. These data are supported by a variety of other mineralogical and petrographical observations. The results indicate that the metal content of the samples is predominantly inherited from the constituent detrital minerals. Reddening of the whole-rock samples does not promote major open-system migration of the heavy metals; rather, contained metals redistribute themselves on an intergranular scale, moving from detrital mineral hosts to the secondary iron oxides. The amount of secondary iron oxides and the fraction of whole-rock metals associated with these oxides increase during red-bed development. In addition, the abundance of well- crystallized iron oxides increases during this period. Differences in the leaching efficiency for various metals are related to differences in metal site distribution and intergranular permeability. Inferred conditions for rapid vs limited removal of metals from red beds are summarized. It is suggested that developed red beds which are well flushed by suitable pore fluids may be sources of significant quantities of heavy metals. -J.E.S.

Zielinski, R. A.; Bloch, S.; Walker, T. R.

1983-01-01

57

Direct measurement of hematite individual particle anisotropy: implications for inclination shallowing in red bed DRMs  

Microsoft Academic Search

Methods to correct for the observed inclination shallowing in sedimentary rocks have been proposed that are based on either models of the geomagnetic field and the resulting directional distribution of paleomagnetic vectors or the magnetic anisotropy of the magnetic minerals carrying the remanence. One limitation of the anisotropy method for hematite-bearing red beds has been the isolation and determination of

D. Bilardello; K. P. Kodama

2007-01-01

58

Palaeogeography of Late Triassic red-beds in Singapore and the Indosinian Orogeny  

NASA Astrophysics Data System (ADS)

A red-bed facies of the Upper Triassic Jurong Formation has been logged on Sentosa Island, Singapore. An overall coarsening and thickening-upward pattern is well developed. The lower part of the section is dominated by purple-red, massive to finely laminated illite-smectite-kaolin-rich mudstones containing thin, discontinuous lenses of fine sandstone marked by low-angle lamination and small ripples. One dinosaur-like foot print has been discovered in a loose block of red mudstone. It is concluded that this is a lacustrine sequence and it is proposed to name the lake, Lake Sentosa. The upper part of the sequence consists of flat-laminated to trough cross-bedded medium-grained sandstone and granule to cobble conglomerates alternating with purple-red mudstone. The mudstone-sandstone packages are arranged in decametre-scale coarsening-upward cycles. The channelling and decimetre-scale cross-bedding characterising the sandstone and conglomeratic beds is evidence for deposition by flashy fluvial flood processes, possibly feeding into the lake as a fresh water delta. One possible dinosaur trackway in granule size conglomerate has been located. Detrital zircon U-Pb ages vary from 2.7 Ba to 209 Ma with significant populations at ˜245 Ma and 220 Ma. These ages throw light on the timing of the Indosinian Orogeny. The molasse red-beds of the Jurong Formation were deposited in a half graben formed in the hangingwall of the Bukit Timah Fault when central Peninsular Malaysia went into extension following the climax of the Indosinian Orogeny in the Late Triassic.

Oliver, Grahame; Prave, Anthony

2013-10-01

59

[Ectoparasites. Part 2: Bed bugs, Demodex, sand fleas and cutaneous larva migrans].  

PubMed

Ectoparasites or epidermal parasites include a very heterogenous group of infections of the outer layers of the skin. Worldwide the most common are scabies, lice, tungiasis, and hookworm-induced cutaneous larva migrans. In recent years, bed bug infestations in hotels or vacation homes seem to have become more frequent. Demodex folliculorum and Demodex brevis are found in the facial and scalp hair follicles in 95% of individuals. Classic Demodex folliculitis is often overlooked in differential diagnostic considerations. This inflammatory sebaceous gland disease as well as Demodex blepharitis both provide a diagnostic and therapeutic challenge. Permethrin can be used topically against demodicosis. Vacationers who go barefoot on beaches in tropical Africa, South America and subtropical Asia risk infestations from female sand fleas. The lesions can be curetted or removed with a punch biopsy, then treated with antiseptics or even systemic antibiotics if a secondary infection develops. Cutaneous larva migrans is one of the most common imported ectoparasite infections from the tropics. Topical treatment measures include thiabendazole or cryotherapy. If the infestation is severe, systemic antihelminthics or ivermectin can be employed. PMID:19701614

Nenoff, P; Handrick, W; Krüger, C; Herrmann, J; Schmoranzer, B; Paasch, U

2009-09-01

60

Influence of bank materials, bed sediment, and riparian vegetation on channel form along a gravel-to-sand transition reach of the Upper Tualatin River, Oregon, USA  

NASA Astrophysics Data System (ADS)

We examined the role of bed sediment size, bank materials, riparian vegetation, and discharge on channel form along a 10-km reach of the Upper Tualatin River, encompassing both gravel and sand-bed reaches. Statistical correlations and analyses of downstream changes of channel morphology reveal that bank materials and bed sediment are the dominant controls on channel cross section form. A rapid downstream reduction in bed sediment size in the gravel-bed channel is followed by an abrupt transition to a narrower, deeper, and less sinuous sand-bed channel with more cohesive bank materials. The simultaneous reductions in channel slope, bed sediment size, and width-to-depth ratio indicate the channel crosses a geomorphic threshold to maintain continuity in sediment transport. This gravel-to-sand transition and associated change in channel form are induced by a break in valley slope and an increase in bank resistance from cohesive bank materials. Bank materials, measured as the average percent silt and clay in banks, are a primary influence on channel form within both subreaches but demonstrate a greater influence on channel width and vertical stability in the gravel-bed channel and on channel depth and lateral stability in the sand-bed channel. Riparian vegetation at current densities and compositions is not a significant control on contemporary channel cross section form and may be responding to the bank and channel stability provided by cohesive bank materials in the laterally dynamic gravel-bed channel.

Labbe, Jim M.; Hadley, Keith S.; Schipper, Aafke M.; Leuven, Rob S. E. W.; Gardiner, Christine Perala

2011-02-01

61

Experimental Observations About The Behavior of The Sheet Flow On Sand Bed Streams and The Reversal Gradation Effect.  

NASA Astrophysics Data System (ADS)

In our land, Catalonia, exists a lot of torrential ephemeral streams. Which are char- acterized by a great floods during typical convective storms. Sediment transport rates are very important in this gravel/sand torrent. Usually, near the cities, they show a 2- 3% slope bed profile. Engineering works or actuations have to deal with this kind of dynamic systems. The stabilization of this torrents is one of the aim of our research at the Polytechnic University of Catalonia (Hydraulic, Marine and environmental De- partment). Typical experiments in a hydraulic flume was normally used to observe the behavior of stabilization structures. The first step in the research is to know the general evolution of the bed profile. Agradation and degradation experiments in a laboratory flume of 20 m length was car- ried out to study the behavior of the steady and unsteady flow with sediment transport. The hydraulic regime of the experiments was set to be supercritical flat bed; sand flow rates about 300gr/s which gives near a 2% equilibrium slope. The most interesting results of those experiments was the reversal gradation of the sand sizes measured along the flume in the final steady state. This kind of effect was reported by Luca Solari and Gary Parker 2000. A 1-D numerical model to solve the Exner and Saint_Venant implicit system of equation were used to compare the evolu- tion of the different experiments. The sheet sand flow produces a great resistance to flow, the experiments shows the influence exhorted by the sand discharge in the flow resistance factor.

Bateman, A.; Aguilar, C.; Roquer, R.; Andreatta, A.; Velasco, D.

62

Vertebrate biochronology of late Triassic red beds in New Mexico  

SciTech Connect

Four vertebrate biochrons can be recognized in Late Triassic strata of New Mexico: (A) Metoposaurus-Rutiodon-Desmatosuchus-Calyptosuchus-Placerias occurs in the Los Esteros member of the Santa Rosa formation near Lamy and is less well known from the lower Petrified Forest Member of the Chinle Formation near San Ysidro, at Mesa del Oro, near Fort Wingate, at Ojo Huelos, and in the Joyita hills. (B) Anaschisma-Belodon-Typothorax-Desmatosuchus-Paratypothorax occurs in the lower Bull Canyon formation in Bull Canyon and near Tucumcari, in the Trujillo Formation near Tucumcari, and possibly in the Travesser Formation of the Dry Cimarron valley, the Petrified Forest Member near Carthage, and the Garita Creek formation near Lamy and Conchas Lake. (C) Anaschisma-Belodon-Typothorax occurs in the upper Bull Canyon formation in Bull Canyon, in the upper Petrified Forest Member near San Ysidro, at Ghost Ranch, near Albuquerque (Correo Sandstone Bed), and possibly in the Sloan Canyon Formation of the Dry Cimarron valley. (D) Anaschisma-new phytosaur, cf. Typothorax-new sphenosuchian, occurs in the Redonda Formation near Tucumcari. The biochronologic ranges of significant vertebrate taxa within New Mexico follow: metoposaurs - Metoposaurus (A-B ), Anaschisma (B-D); phytosuars - Rutiodon (A), Belodon (B-C), new taxon (D); aetosaurs - Calyptosuchus (A), Desmatosuchus (A-B), Paratypothorax (B), Typothorax (B-D ); rauisuchians - Postosuchus (A-B), Chatterjeea (B-C); sphenosuchians - new taxon 1 (A), Hesperosuchus (B), new taxon 2 (D); dinosaurs - ornithischians (B), Coelophysis (C), other theropods (B-C); therapsids - Placerias (A), Pseudotriconodon (C). Biochron A may be Carnian in age, whereas biochrons B-D are probably early to middle ( ) Norian.

Hunt, A.P. (Univ. of New Mexico, Albuquerque (USA))

1989-09-01

63

Drivers of bacterial diversity dynamics in permeable carbonate and silicate coral reef sands from the Red Sea  

PubMed Central

Permeable sediments and associated microbial communities play a fundamental role in nutrient recycling within coral reef ecosystems by ensuring high levels of primary production in oligotrophic environments. A previous study on organic matter degradation within biogenic carbonate and terrigenous silicate reef sands in the Red Sea suggested that observed sand-specific differences in microbial activity could be caused by variations in microbial biomass and diversity. Here, we tested this hypothesis by comparing bacterial abundance and community structure in both sand types, and by further exploring the structuring effects of time (season) and space (sediment depth, in/out-reef). Changes in bacterial community structure, as determined via automated ribosomal intergenic spacer analysis (ARISA), were primarily driven by sand mineralogy at specific seasons, sediment depths and reef locations. By coupling ARISA with 16S-ITS rRNA sequencing, we detected significant community shifts already at the bacterial class level, with Proteobacteria (Gamma-, Delta-, Alpha-) and Actinobacteria being prominent members of the highly diverse communities. Overall, our findings suggest that reef sand-associated bacterial communities vary substantially with sand type. Especially in synergy with environmental variation over time and space, mineralogical differences seem to play a central role in maintaining high levels of bacterial community heterogeneity. The local co-occurrence of carbonate and silicate sands may thus significantly increase the availability of microbial niches within a single coral reef ecosystem.

Schottner, Sandra; Pfitzner, Barbara; Grunke, Stefanie; Rasheed, Mohammed; Wild, Christian; Ramette, Alban

2011-01-01

64

Treatment of wastewater from red and tropical fruit wine production by zeolite anaerobic fluidized bed reactor  

Microsoft Academic Search

A study of the anaerobic treatment of wastewaters derived from red (RWWW) and tropical fruit wine (TFWWW) production was carried out in four laboratory-scale fluidized bed reactors with natural zeolite as bacterial support. These reactors operated at mesophilic temperature (35°C). Reactors R1 and R2 contained Chilean natural zeolite, while reactors R3 and R4 used Cuban natural zeolite as microorganism support.

S. Montalvo; L. Guerrero; R. Borja; I. Cortés; E. Sánchez; M. F. Colmenarejo

2008-01-01

65

Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions  

USGS Publications Warehouse

Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

Jamieson, E. C.; Rennie, C. D.; Jacobson, R. B.; Townsend, R. D.

2011-01-01

66

Cretaceous oceanic red beds (CORBs): Different time scales and models of origin  

NASA Astrophysics Data System (ADS)

The Cretaceous oceanic red bed (CORB) is a newly opened window on global oceanic and climate changes during the Cretaceous greenhouse world. As a result of the International Geoscience Programmes 463, 494 and 555 (2002-2010), CORBs have been documented in many places by numerous publications. The principle goal of this paper is to summarize scientific advances on CORBs including chronostratigraphy, sedimentology, mineralogy, elemental and isotopic geochemistry, and their relationship to oceanic anoxic events (OAEs), palaeoclimate and palaeoceanography. We propose a new geochemical classification of the CORBs using CaO, Al2O3 and SiO2 values, which lithologically refer to marly, clayey, and cherty CORBs respectively. Detailed mineralogical studies indicate that hematite, goethite and Mn2 +-bearing calcite are the minerals imparting the red color of CORBs. Hematite clusters of several to tens of nanometers in the calcite structure are the main cause of the red coloring of limestones, and the Mn2 +-bearing calcite gives additional red color. Goethite was thought to form originally with hematite, and was subsequently transformed to hematite during late diagenesis. Chronostratigraphic data allow the distinction of two groups of CORBs by their durations. Short-term CORBs are generally less than 1 myr in duration, and seem to be on the scale of Milankovitch cycles. During the deposition of Cretaceous reddish intervals from ODP cores 1049 and 1050, low primary productivity and relatively high surface temperature resulted in low organic carbon flux into the sediments which reduced oxygen demand and produced oxidizing early diagenetic conditions. In such an oxic environment, iron oxides formed imparting the reddish color. The long-term CORBs' depositional events lasted longer than 4 myr, and may be a possible consequence of the OAEs. Enhanced amounts of organic carbon and pyrite burial during and after the OAEs would have resulted in a large and abrupt fall in atmospheric CO2 concentration, which probably induced significant global climatic cooling during and after the OAEs. Global cooling would have enhanced formation of cold deep water, increasing its oxidizing capacity due to the greater content of dissolved oxygen and would promote formation of oceanic red beds. Sedimentological, mineralogical and geochemical data indicate that CORBs were deposited under highly oxic, oligotrophic conditions probably at a low sedimentation rate. The Cretaceous red and white limestones from Italy have similar compositions of terrestrial input-sensitive elements (Al, Ti, K, Mg, Rb, Zr), higher contents of Fe2O3, and depleted redox-sensitive elements (V, Cr, Ni, and U) and micronutrient elements Cu, Zn, indicating similar provenance sources but red limestones were deposited under more oxic conditions at the sediment-water interface than white limestones. The Cretaceous red shales such as those from the North Atlantic and Tibet have similar mineralogy and geochemistry as the Late Cenozoic red clays in the Pacific Ocean and the environment where both are formed was well-oxidizing at a very low sedimentation rate. We compiled seventeen published stratigraphic examples of Phanerozoic oceanic red beds including the Late Cenozoic red clays in the Pacific. Different hypotheses explain the origin of red pigmentation of limestones and shales including (1) detrital origin of iron derived from continental weathering; (2)iron-bacterial mediation at the time of sedimentation; and (3) iron oxidation in oligotrophic, highly oxic environment. Additional research on Phanerozoic oceanic red beds is needed in order to better document their origin and palaeoceanographic and palaeoclimatic significance.

Hu, Xiumian; Scott, Robert W.; Cai, Yuanfeng; Wang, Chengshan; Melinte-Dobrinescu, Mihaela C.

2012-12-01

67

A New Uniform Flow Depth-Discharge Predictor for Large, Low-slope, Sand-bed Rivers  

NASA Astrophysics Data System (ADS)

Recent evidence suggests that density stratification effects induced by suspended sediment can be significant for large, low-slope, sand-bed rivers, particularly for bankfull flow events. Here a simple modification to the standard uniform flow velocity profile is presented, and a new depth-discharge predictor is developed. The new predictor accounts for density stratification effects through a dependence on the total suspended load concentration, as well as bedform roughness using a simple analogy with the sand-grain roughness for plane-bed flows. The vertical density gradient induced by the suspended load decreases turbulent mixing, typically accounted for by decreasing the eddy viscosity. The method presented here is based on a simplified approach, with the goal of an easy to use depth-discharge predictor which accounts for density stratification. Several researchers have investigated the effects of density stratification on velocity and concentration profiles, typically using a modified eddy viscosity given as a function of flux or gradient Richardson number. It has recently been shown, however, that the two parameters which dominate gross flow Richardson number variations in sand-bed rivers are the total suspended concentration and bed (or friction) slope. Here it is assumed that the effects of stratification on eddy viscosity can be approximated as constant over the depth. This assumption dictates a simple adjustment to the log-law (or power-law) velocity profile, with the gross reduction in eddy viscosity given as a function of the ratio of concentration to slope. The functional relation between reduced eddy viscosity and concentration/slope is developed from a previous study by the authors, which combines theory and data from sand-bed rivers. It is noted that the simplified approach has the same effect as an ad hoc reduction of the von Karman constant, i.e. a reduction in eddy viscosity which is constant over the depth. The modified power-law velocity profile is integrated resulting in a depth-discharge equation reminiscent of the Manning-Strickler form. In contrast to the standard depth-discharge predictors, however, the equation presented here contains a dependence on the total suspended load concentration, thus incorporating stratification effects in a simplified manner. In analogy with the equivalent sand-bed roughness, a composite roughness height is assumed to be directly proportional to dune height. The Julien dune height predictor and data are then used to determine the constant of proportionality. The new depth-discharge equation can be solved directly for depth, and provides an easy to use estimator of flow depth in large sand-bed rivers which accounts for both stratification effects and bedform roughness. Since the total suspended concentration is required as input, the new equation must be coupled to either measurements of sediment transport or a transport predictor.

Wright, S. A.; Parker, G.

2001-12-01

68

Application of CFD modeling to hydrodynamics of CycloBio fluidized sand bed in recirculating aquaculture systems  

NASA Astrophysics Data System (ADS)

To improve the efficiency of a CycloBio fluidized sand bed (CB FSB) in removal of dissolved wastes in recirculating aquaculture systems, the hydrodynamics of solid-liquid flow was investigated using computational fluid dynamics (CFD) modeling tools. The dynamic characteristics of silica sand within the CB FSB were determined using three-dimensional, unsteady-state simulations with the granular Eulerian multiphase approach and the RNG k-? turbulence model, and the simulation results were validated using available lab-scale measurements. The bed expansion of CB FSB increased with the increase in water inflow rate in numerical simulations. Upon validation, the simulation involving 0.55 mm particles, the Gidaspow correlation for drag coefficient model and the Syamlal-O'Brien correlation for kinetic granular viscosity showed the closest match to the experimental results. The volume fraction of numerical simulations peaked as the wall was approached. The hydrodynamics of a pilot-scale CB FSB was simulated in order to predict the range of water flow to avoid the silica sand overflowing. The numerical simulations were in agreement with the experimental results qualitatively and quantitatively, and thus can be used to study the hydrodynamics of solid-liquid multiphase flow in CB FSB, which is of importance to the design, optimization, and amplification of CB FSBs.

Liu, Yao; Song, Xiefa; Liang, Zhenlin; Peng, Lei

2013-11-01

69

Cretaceous black shale and the oceanic red beds: Process and mechanisms of oceanic anoxic events and oxic environment  

Microsoft Academic Search

The Cretaceous is an important period in which many geological events occurred, especially the OAEs (oceanic anoxic events)\\u000a which are characterized by black shale, and the oxic process characterized by CORBs (Cretaceous oceanic red beds). In this\\u000a paper, the causative mechanism behind the formation of black shale and the oceanic red beds are described in detail. This\\u000a may explain how

Zhenguo Zhang; Nianqiao Fang; Lianfeng Gao; Baoling Gui; Muhua Cui

2008-01-01

70

Paleokarstic phenomena of the Lower Ordovician red bed sequences of the Arbuckle group, southern Oklahoma  

SciTech Connect

Oil and gas production has been reported recently from paleokarstic Arbuckle reservoirs in the Ardmore and Arkoma basin. The West Spring Creek and the Kindblade formations apparently exhibit karstic features. The most extensive surface exposure of these formations is on the southern flank of the Arbuckle anticline along Interstate 35 north of Ardmore, Oklahoma. The lithology is predominantly limestone, ranging from argillaceous mudstone to oolitic and/or bioclastic grainstones. However, minor amounts of sandstone were also observed.These lithologies are characteristic of various peritidal facies. Of particular interest in this outcrop are three distinct red bed zones. Although the zones are part of the repetitive shallowing-upward cycles that characterize the West Spring Creek Formation, ample evidence suggests the red beds represent subaerial exposure surfaces where karstification took place. Many of the thin bedded, rubbly mudstones and wackestones actually represent varieties of breccia commonly associated with karst. Collapse and crackle breccia are most commonly observed. Small solution channels and other vugs are usually completely occluded by calcite cement. However, solution cavities or vugs with diameters larger than 10 cm (3.9 in.) are lined with drusy calcite. Hematite-impregnated sediment occurs as thinly laminated infilling of solution vugs and cavities and also acts as a cementing agent of collapse breccias. Preliminary evidence suggests that karstification processes were active during Arbuckle deposition.

Musselman, J.L. (Oklahoma State Univ., Stillwater (United States))

1991-06-01

71

Effects of sand addition on turbulent flow over an immobile gravel bed  

Microsoft Academic Search

The factors controlling the complex interaction of a coarse streambed with flow and sediment are difficult to measure. However, planning for reservoir flushing or dam removal requires knowledge of these interactions. In both cases, impounded sediments are introduced to channel beds that have had fine sediment particles removed without replacement. The channel bed pore space interacts with the flow and

D. G. Wren; E. J. Langendoen; R. A. Kuhnle

2011-01-01

72

Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters  

USGS Publications Warehouse

Septic tank systems are an important source of NO3- to many aquifers, yet characterization of N mass balance and isotope systematics following septic tank effluent discharge into unsaturated sediments has received limited attention. In this study, samples of septic tank effluent before and after transport through single-pass packed-bed filters (sand filters) were evaluated to elucidate mass balance and isotope effects associated with septic tank effluent discharge to unsaturated sediments. Chemical and isotopic data from five newly installed pairs and ten established pairs of septic tanks and packed-bed filters serving single homes in Oregon indicate that aqueous solute concentrations are affected by variations in recharge (precipitation, evapotranspiration), NH4+ sorption (primarily in immature systems), nitrification, and gaseous N loss via NH3 volatilization and(or) N2 or N2O release during nitrification/denitrification. Substantial NH4+ sorption capacity was also observed in laboratory columns with synthetic effluent. Septic tank effluent ??15N-NH4+ values were almost constant and averaged + 4.9??? ?? 0.4??? (1 ??). In contrast, ??15N values of NO3- leaving mature packed-bed filters were variable (+ 0.8 to + 14.4???) and averaged + 7.2??? ?? 2.6???. Net N loss in the two networks of packed-bed filters was indicated by average 10-30% decreases in Cl--normalized N concentrations and 2-3??? increases in ??15N, consistent with fractionation accompanying gaseous N losses and corroborating established links between septic tank effluent and NO3- in a local, shallow aquifer. Values of ??18O-NO3- leaving mature packed-bed filters ranged from - 10.2 to - 2.3??? (mean - 6.4??? ?? 1.8???), and were intermediate between a 2/3 H2O-O + 1/3 O2-O conceptualization and a 100% H2O-O conceptualization of ??18O-NO3- generation during nitrification.

Hinkle, S. R.; Bohlke, J. K.; Fisher, L. H.

2008-01-01

73

Responses of Red-Osier Dogwood to Oil Sands Tailings Treated with Gypsum or Alum  

Microsoft Academic Search

or composite tailings (CT), are currently being inves- tigated. The application of composite or consolidated tailings (CT) technol- In the CT process, the fines and sand fractions are ogy provides Alberta's oil sands industry with a means of reducing treated with a coagulant aid to produce a nonsegregating the volume of the fines fraction in extraction tailings and allows mixture

E. Redfield; C. Croser; J. J. Zwiazek; M. D. MacKinnon; C. Qualizza

2003-01-01

74

Help for declining natural gas production seen in the unconventional sources of natural gas. [Eastern shales, tight sands, coal beds, geopressured zones  

SciTech Connect

Oil imports could be reduced and domestic gas production increased if additional gas production is obtained from four unconventional resources-eastern Devonian shales, tight sands, coal beds, and geopressured zones. Gas produced from these resources can help maintain overall production levels as supplies from conventional gas sources gradually decline. The eastern shales and western sands are the chief potential contributors in the near term. Further demonstrations of coal bed methane's recovery feasibility could improve the prospects for its production while future geopressured methane production remains speculative at this time.

Staats, E.B.

1980-01-10

75

Paleomagnetism of some Precambrian basaltic flows and red beds, Eastern Grand Canyon, Arizona  

USGS Publications Warehouse

Lava flows and red sandstone beds near the middle of the Upper Precambrian Grand Canyon Series exhibit stable remanent magnetization. The beds are about 1000 m stratigraphically above rocks of the Grand Canyon Series for which paleomagnetic poles have been reported. All specimens were subjected to stepwise thermal (200??-700??C) or alternating field (25-5000 Oe) demagnetization for the determination of characteristic magnetization. The pole for two flows and an intercalated sandstone bed of the Cardenas Lavas of Ford, Breed and Mitchell (upper Unkar Group), is at 174.6W, 0.4N (N = 10, K = 50, ??95 = 6.9??). The pole for a weathered zone developed across the Cardenas Lavas is at 167.8W, 49.4N (N = 5, K = 79, ??95 = 8.6??). The pole for directly overlying sandstone of the Nankoweap Formation of Maxson is at 174.4E, 12.5N (N = 6, K = 105, ??95 = 6.6??). These poles lie on or near, and appear to follow, part of an apparent polar wandering path recently proposed for the Precambrian of North America by Spall. If the fit is not accidental, little or no rotation has occurred between north-central Arizona and parts of the North American continent used to define the proposed path. ?? 1973.

Elston, D. P.; Robert, Scott, G.

1973-01-01

76

Does solid carbon burn in oxygen to give the gaseous intermediate CO or produce CO 2 directly? Some experiments in a hot bed of sand fluidized by air  

Microsoft Academic Search

Relatively large spheres of non-porous graphite (diam. 2–12 mm) have been burned in electrically heated beds of sand, fluidized by air. The rate of reaction of the carbon was derived from measurements of the concentrations of CO and CO2 in the gases leaving the bed. The carbon particle's temperature was monitored continuously during its combustion using a very fine thermocouple

A. N. Hayhurst; M. S. Parmar

1998-01-01

77

Effect of Grain Crushing and Bedding Plane Inclination on Ras en-Naqab Natural Sand Behavior  

Microsoft Academic Search

This pa per p resents an e xperimental investigation f or i nherent ani sotropy an d particle breakage f or n atural Ras en-Naqab sand so uthern J ordan. The nat ural s and s pecimens were subjected to one dim ensional compression to induce breakage. Th e grain size distributions of the s pecimens were re ported before

Reyad Al Dwairi; Omar Al-Hattamleh; Faisal Al-Shalabi; Talib Al-Rousan

2009-01-01

78

Paleomagnetism of Devonian red beds in the Appalachian Plateau and Valley and Ridge provinces  

NASA Astrophysics Data System (ADS)

Samples of red and green fluvial to marine sandstones in the Hampshire Formation/Catskill Group from regional-scale folds across the structural trend of the Valley and Ridge (VR) and Appalachian Plateau (AP) provinces of West Virginia were analyzed to test models for remagnetization of red sandstones. The red sandstones contain a dominant secondary Pennsylvanian-Permian magnetization with south declinations (154.8°-166.9°) and shallow inclinations (0.2°-19.3°) that resides in hematite and is interpreted as a chemical remanent magnetization (CRM) acquired during the Kiaman reversed superchron. Incremental fold tests for this CRM yield generally prefolding results from the AP rocks and synfolding results from the VR rocks. This suggests that the remanence acquisition in the AP may have occurred within the time span of deformation. A second, high unblocking temperature apparent synfolding CRM is also found in a few samples of the red sandstones and is distinguished by slightly steeper inclinations than the dominant component on northwest dipping beds. Specimens from green sandstone have weak intensities and are dominated by a modern viscous remanence. Thin section analysis shows the presence of authigenic specular hematite cement and submicron particle size red hematite pigment. Geochemical/fluid inclusion studies indicate that the rocks were exposed to mixed methane-saturated formational and meteoric fluids with no evidence that external warm orogenic fluids altered the rocks. A working model for CRM acquisition involves (1) methane reduction of previously formed iron phases and mobilization of iron and (2) a return to oxidizing conditions and precipitation of new authigenic hematite as a result of the introduction of meteoric fluids just prior to and during uplift. The green sandstones probably formed as a result of gleying which occurs in paleosols although they could be a relic of or preserve evidence of the reduction phase.

Cox, Eric; Elmore, R. Douglas; Evans, Mark

2005-08-01

79

Expression of syndepositional tectonic uplift in Permian Goose Egg formation (Phosphoria equivalent) carbonates and red beds of Sheep Mountain anticline, Bighorn basin, Wyoming  

SciTech Connect

Based on detailed field observations at Sheep Mountain, a doubly plunging anticline in the northeastern Bighorn basin in Wyoming, there appears to have been active tectonic uplift at this site contemporaneous with Pennsylvanian and Permian sedimentation. The Permian (Leonardian to Guadalupian) Goose Egg Formation at Sheep Mountain consists of 25-60 m of silty red beds (including minor carbonate and evaporite units) capped by 15-30 m of dominantly intertidal carbonates (the Ervay Member). A strong lateral variation of facies normal to the trend of the anticline is found within the red-bed sequence: carbonate beds on the anticline flanks are transitional with a gypsum/anhydrite facies along the crest. Similarly, shales on the anticline limbs grade into sandstones near the fold axis, indicating a paleohigh roughly coincidental with the present-day anticline crest. Ervay deposition (late Guadalupian) was marked by a more extensive uplifted structure in a marginal marine setting. On Sheep Mountain the unit is typified by intertidal fenestral carbonates, whereas outcrops to the east suggest a restricted marine facies and outcrops to the west reflect a more open marine environment. Thin sand lenses present in the Ervay are thought to represent terrigenous sediments blown onto the sometimes emergent bank which were then captured through adhesion and cementation. Anticlinal features similar to Sheep Mountain are common along the eastern margin of the Bighorn basin. When found in the subsurface, these structures are often associated with hydrocarbon production from the Ervay Member. Tectonic uplift contemporaneous with deposition of this unit may explain the localization of the productive fenestral facies on the present-day anticlines.

Simmons, S.P.; Ulmer, D.S.; Scholle, P.A.

1989-03-01

80

Paleomagnetism of red beds of Early Devonian age from Central Iran  

NASA Astrophysics Data System (ADS)

Paleomagnetic results are reported from 13 sites of red beds of Early Devonian age from Central Iran. Detailed paleomagnetic analyses were carried out. Two types of partial progressive demagnetization were applied, one using alternating magnetic fields, the other heating. These procedures resulted in the detection of the characteristic remanences with a mean direction with D = 24.2°, I = 1.3° (? 95 = 10.1°). The paleomagnetic pole is located at 51.3°N, 163.7°W. If one shifts the Iranian landmass to its most likely position in the Gondwana configuration, then the position of the paleomagnetic pole coincides with the alternative polar wander path [14,15] which crossed South America in early Middle Paleozoic times.

Wensink, Hans

1983-05-01

81

Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters.  

PubMed

Septic tank systems are an important source of NO3(-) to many aquifers, yet characterization of N mass balance and isotope systematics following septic tank effluent discharge into unsaturated sediments has received limited attention. In this study, samples of septic tank effluent before and after transport through single-pass packed-bed filters (sand filters) were evaluated to elucidate mass balance and isotope effects associated with septic tank effluent discharge to unsaturated sediments. Chemical and isotopic data from five newly installed pairs and ten established pairs of septic tanks and packed-bed filters serving single homes in Oregon indicate that aqueous solute concentrations are affected by variations in recharge (precipitation, evapotranspiration), NH4+ sorption (primarily in immature systems), nitrification, and gaseous N loss via NH3 volatilization and(or) N2 or N2O release during nitrification/denitrification. Substantial NH4+ sorption capacity was also observed in laboratory columns with synthetic effluent. Septic tank effluent delta15N-NH4+ values were almost constant and averaged +4.9 per thousand+/-0.4 per thousand (1 sigma). In contrast, delta15N values of NO3(-) leaving mature packed-bed filters were variable (+0.8 to +14.4 per thousand) and averaged +7.2 per thousand+/-2.6 per thousand. Net N loss in the two networks of packed-bed filters was indicated by average 10-30% decreases in Cl(-)-normalized N concentrations and 2-3 per thousand increases in delta15N, consistent with fractionation accompanying gaseous N losses and corroborating established links between septic tank effluent and NO3(-) in a local, shallow aquifer. Values of delta18O-NO3(-) leaving mature packed-bed filters ranged from -10.2 to -2.3 per thousand (mean -6.4 per thousand+/-1.8 per thousand), and were intermediate between a 2/3 H2O-O+1/3 O2-O conceptualization and a 100% H2O-O conceptualization of delta18O-NO3(-) generation during nitrification. PMID:18835629

Hinkle, Stephen R; Böhlke, J K; Fisher, Lawrence H

2008-12-15

82

AMS Fabric of a CRM in Hematite-Bearing Samples: Evidence of DRMs in Natural Red Beds  

NASA Astrophysics Data System (ADS)

Anisotropy of magnetic susceptibility (AMS) and anisotropy of isothermal remanence (AIR) in red sedimentary rocks both typically show a bedding parallel foliation with minimum axes clustered perpendicular to the bedding plane. Our studies have observed this type of magnetic fabric in red bed units that have a range of ages and come from widespread localities. These units include the Mississippian Mauch Chunk Formation from the Appalachians, the Triassic Passaic Formation from the Newark basin in Pennsylvania, the Cretaceous Kapusaliang Formation from the Tarim basin in China, and the early Mesozoic Kayenta and Chinle Formations from the Colorado Plateau in southwestern North America. Bedding parallel foliations are also observed in magnetite-bearing rocks that carry a depositional remanence (DRM), suggesting the possibility of a DRM in red beds, even though the conventional wisdom is that they carry a post-depositional chemical remanent magnetization (CRM). Before the typical magnetic fabric of red beds can be used to indicate their type of remanence, we must determine what the magnetic fabric of a CRM looks like. For this reason, I conducted a series of hematite-growth experiments following the procedures outlined by Stokking and Tauxe (1987). I grew hematite in the laboratory on stacks of glass-fiber filter papers and in slurries of quartz and kaolinite. The hematite was grown from a ferric nitrate solution heated to 95° C for 8 hours. The samples were then dehydrated in a vacuum at room temperature for approximately 38 hours. It was possible to thermally demagnetize the eight filter paper samples to 350° C, but the six kaolinite-quartz samples were grown in plastic sample cubes and could only be thermally demagnetized to 150° C, enough to remove the thermoviscous magnetization acquired by the samples during the heating at 95° C. The mean CRM acquired by the red-brown magnetic phase grown in the experiments was within its alpha-95 of the steeply inclined (inclination=60°) ambient magnetic field. The kaolinite-quartz samples had a very scattered remanence, probably due to the physical disturbance of the samples upon the initial application of the vacuum. In both the filter paper and kaolinite-quartz experiments the AMS fabric of the CRM-carrying grains was foliated with the maximum and intermediate principal axes defining a great circle that passes through the mean CRM direction and is moderately inclined (approximately 45°) to the horizontal. The moderately inclined great circle defined by the maximum-intermediate principal axes is quite distinct from the horizontal maximum-intermediate axes observed in the natural red bed samples, despite red bed characteristic remanences that range from nearly horizontal (Passaic, Chinle, Kayenta) to as steep as 30° (Mauch Chunk, Kapusaliang). This observation suggests that red bed characteristic remanence is typically a DRM, rather than a CRM. This has implications for interpreting red bed remanence since DRMs in hematite-bearing red beds may have large inclination errors.

Kodama, K. P.

2002-12-01

83

Forms and availability of sediment phosphorus in carbonate sand of Bermuda seagrass beds  

Microsoft Academic Search

Primary production by seagrasscs in tropical and subtropical carbonate sediments often appears to be phosphorus (P) limited, and several studies have sought to identify the possible sources of P for long-term growth. Here, we quantify concentrations of particulate and dissolved P and fluoride (F-) in carbonate sediments, sediment-water P exchange, and leaf-tissue P concentrations in three seagrass beds in Bermuda.

Henning Skovgaard Jensen; Karen J. McGlathery; Roxanne Marino; Robert W. Howarth

1998-01-01

84

The significance of fine scale variations in magnetization in a sequence of continental red-beds  

SciTech Connect

A sequence of Upper Permian continental red-beds from southern France has been studied using fully oriented samples as well as mining drill core segments. A systematic sampling has been carried out, with stratigraphic intervals ranging from 10 m down to 5 mm. In order to investigate the lateral variability of the magnetization, samples were obtained from several (up to 10) stratigraphically equivalent sections located a few centimeters to 100 m apart, and at four different sandstone and siltstone horizons (25 cm to 2 m thick). The stratigraphic variations of directional data from distinct sites generally correlate well, even when observed at a scale of a few centimeters, thus indicating that they originate most probably from variations of the geomagnetic field rather than from geologically induced perturbations. In addition, these correlations show that the isochrons of magnetization acquisition are not horizontal but follow the bed thickness variations inherent at continental deposits, which favors an early locking of the remanence in the rock history. Magnetization intensity data seem to provide lithological information with a much greater resolution than do the more commonly used susceptibility measurements. While in most cases the susceptibility shows little or no variability, the intensity variations are very clear and match lithological changes. Again a very good correlation is observed between different sites at the same stratigraphic level. The intensity variations are cyclic and can reveal similarity cyclic changes in the conditions of deposition.

Maillol, J.M.; Evans, M.E. (Univ. of Alberta, Edmonton (Canada))

1991-03-01

85

Granular spirals on erodible sand bed submitted to a circular fluid motion  

NASA Astrophysics Data System (ADS)

An experimental study of a granular surface submitted to a circular fluid motion is presented. The appearance of an instability along the sand-water interface is observed beyond a critical radius rc. This creates ripples with a spiral shape on the granular surface. A phase diagram of such patterns is constructed and discussed as a function of the rotation speed ? of the flow and as a function of the height of water h above the surface. The study of rc as a function of h, ?, and r parameters is reported. Thereafter, rc is shown to depend on the rotation speed according to a power law. The ripple wavelength is found to decrease when the rotation speed increases and is proportional to the radial distance r. The azimuthal angle ? of the spiral arms is studied. It is found that ? scales with h?r. This lead to the conclusion that ? depends on the fluid momentum. Comparison with experiments performed with fluids allows us to state that the spiral patterns are not the signature of an instability of the boundary layer.

Caps, H.; Vandewalle, N.

2003-09-01

86

Slow Sand Filtration: Influences of Selected Process Variables.  

National Technical Information Service (NTIS)

Biological activity within the sand bed had the strongest influence on removal efficiency of total coliform bacteria by slow sand filtration, as determined by six pilot filters. Temperature, sand bed depth, and sand size also had a strong influecee.

W. D. Bellamy D. W. Hendricks G. S. Logsdon

1985-01-01

87

The Cyborg Astrobiologist: scouting red beds for uncommon features with geological significance  

NASA Astrophysics Data System (ADS)

The `Cyborg Astrobiologist' has undergone a second geological field trial, at a site in northern Guadalajara, Spain, near Riba de Santiuste. The site at Riba de Santiuste is dominated by layered deposits of red sandstones. The Cyborg Astrobiologist is a wearable computer and video camera system that has demonstrated a capability to find uncommon interest points in geological imagery in real time in the field. In this second field trial, the computer vision system of the Cyborg Astrobiologist was tested at seven different tripod positions, on three different geological structures. The first geological structure was an outcrop of nearly homogeneous sandstone, which exhibits oxidized-iron impurities in red areas and an absence of these iron impurities in white areas. The white areas in these `red beds' have turned white because the iron has been removed. The iron removal from the sandstone can proceed once the iron has been chemically reduced, perhaps by a biological agent. In one instance the computer vision system found several (iron-free) white spots to be uncommon and therefore interesting, as well as several small and dark nodules. The second geological structure was another outcrop some 600 m to the east, with white, textured mineral deposits on the surface of the sandstone, at the bottom of the outcrop. The computer vision system found these white, textured mineral deposits to be interesting. We acquired samples of the mineral deposits for geochemical analysis in the laboratory. This laboratory analysis of the crust identifies a double layer, consisting of an internal millimetre-size layering of calcite and an external centimetre-size efflorescence of gypsum. The third geological structure was a 50 cm thick palaeosol layer, with fossilized root structures of some plants. The computer vision system also found certain areas of these root structures to be interesting. A quasi-blind comparison of the Cyborg Astrobiologist's interest points for these images with the interest points determined afterwards by a human geologist shows that the Cyborg Astrobiologist concurred with the human geologist 68% of the time (true-positive rate), with a 32% false-positive rate and a 32% false-negative rate. The performance of the Cyborg Astrobiologist's computer vision system was by no means perfect, so there is plenty of room for improvement. However, these tests validate the image-segmentation and uncommon-mapping technique that we first employed at a different geological site (Rivas Vaciamadrid) with somewhat different properties for the imagery.

McGuire, Patrick Charles; Díaz-Martínez, Enrique; Ormö, Jens; Gómez-Elvira, Javier; Rodríguez-Manfredi, José Antonio; Sebastián-Martínez, Eduardo; Ritter, Helge; Haschke, Robert; Oesker, Markus; Ontrup, Jörg

2005-04-01

88

Upper Cretaceous oceanic red bed foraminifera from the southern Norwegian Sea  

NASA Astrophysics Data System (ADS)

Foraminiferal assemblages of Cretaceous Oceanic Red Beds (CORBs), which are geographically widespread and whose deposition reflects oligotrophic and well-oxygenated deep-water environments, have been described from the Atlantic, the Pacific and the Tethys. No detailed taxonomic study was, however, published on foraminifera from CORBs in the Norwegian Sea, though their existence was previously mentioned. This study, thus, investigates assemblages from a red sediment interval of the uppermost Santonian-middle Campanian Nise Formation in well 6306/5-1 drilled in the southern Norwegian Sea for taxonomy and their palaeoenvironmental implications based on morphogroup analysis. The assemblages are relatively highly diversified and composed of 61 deep-water agglutinated taxa without any calcareous forms. Biostratigraphically important Upper Cretaceous species, such as Caudammina gigantea and Uvigerinammina jankoi, are not recorded. The common occurrence of tubular forms, high diversity and the absence of small species of Upper Cretaceous abyssal fauna suggest a bathyal setting for the depositional environment of the CORBs in the Norwegian Sea. The absence of calcareous components indicates that they were deposited near or below the regional calcium carbonate compensation depth. The fauna from the red sediment interval shows similarity to both the mesotrophic flysch-type biofacies, for example in the presence of robust tubular forms and rzehakinids, and the CORB assemblages previously described in the abundant occurrence of infauna in environments with low flux of organic matter. This intermediate characteristics of the Norwegian CORB fauna is probably related to a shallower bathyal setting and higher flux of organic matter to the seafloor due to the proximity to land in a narrow proto-Norwegian Sea than abyssal and truly oligotrophic depositional environments of other CORBs. As sedimentation of CORBs can be regarded as the primary type of background hemipelagic sedimentation in deep-sea conditions, the CORB assemblages of this study may represent a background deep-sea foraminiferal assemblage of the Norwegian Sea, which was tectonically active during the Late Cretaceous and in which a thick unit of Upper Cretaceous turbidites was deposited.

Setoyama, Eiichi; Kaminski, Michael A.

2014-05-01

89

Direct measurement of hematite individual particle anisotropy: implications for inclination shallowing in red bed DRMs.  

NASA Astrophysics Data System (ADS)

Methods to correct for the observed inclination shallowing in sedimentary rocks have been proposed that are based on either models of the geomagnetic field and the resulting directional distribution of paleomagnetic vectors or the magnetic anisotropy of the magnetic minerals carrying the remanence. One limitation of the anisotropy method for hematite-bearing red beds has been the isolation and determination of a rock's detrital hematite individual particle anisotropy. Up to now, our red bed inclination shallowing corrections have been dependent on estimates of hematite individual particle anisotropy using data fit to theoretical correction curves. We have developed a technique for preferentially extracting the detrital hematite particles in a sample in order to directly measure their individual particle anisotropy. The method involves crushing of the sample followed by ball milling and sieving to ensure that the rock particles are smaller than 4?. The resulting slurry was then placed in an ultrasonic cleaner for at least 24 hours and finally centrifuged at 1000 rpm for 20 minutes in order to separate the dense, gray iron oxide particles from the red pigmentary grains. The gray, iron oxide-rich slurry was collected by hand and circulated in a magnetic extraction apparatus. The magnetic separate was then collected over a period of two to three weeks. Small amounts of the magnetic separates where mixed in a slow-drying epoxy resin for 24 hours and placed in a DC magnetic field (100 mT to 180 mT) in order to align the grains. The bulk IRM anisotropy of the epoxy samples provides an average individual particle anisotropy for the magnetic grains. Separates were collected from samples of the Mauch Chunk Fm. of Pennsylvania, the Maringouin and the Shepody Fms of New Brunswick/ Nova Scotia and the Kapusaliang Fm. of northwestern China. IRM acquisitions experiments were performed in fields of up to 1.2 T in order to identify the magnetic mineralogies present. Remanence appears to be carried by a low coercivity phase (~50 mT) interpreted to be secondary magnetite and a higher coercivity phase (~350 mT) interpreted to be primary hematite for the Shepody and Maringouin Fms or just one high coercivity component (200- 250 mT) interpreted as primary hematite for the Mauch Chunk and Kapusaliang Fms. Hematite individual particle anisotropy was measured by imparting a 1.2 T IRM to the specimens in 9 different orientations followed by AF demagnetization at 100 mT. Calculated individual particle anisotropy values ranged between 1.28 and 1.45 with bulk anisotropies of ~$40%. Inclination corrections using the directly measured individual particle anisotropies indicate significant inclination shallowing for the Mauch Chunk and Kapusaliang Fms, while more moderate shallowing for the Maringouin and Shepody Fms. Curve fitting techniques with added constraints give a good first order approximation of the individual particle anisotropy, however direct measurement is preferable. The measured particle anisotropies for hematite are low and suggest that there is the potential for significant amounts of shallowing for a hematite DRM. This observation is consistent with redeposition experiments performed by Tauxe and Kent [1984] and the notion that depositional inclination of hematite may suffer from more shallowing than magnetite because of its lower spontaneous magnetization making it more affected by gravitational forces.

Bilardello, D.; Kodama, K. P.

2007-12-01

90

Hydraulic and topographic response of sand-bed rivers to woody riparian seedlings: field-scale laboratory methods and results  

NASA Astrophysics Data System (ADS)

Feedbacks between topography, flow fields and vegetation community structure are fundamental processes in many rivers. In addition, predicting seedling mortality in response to flood events requires a detailed understanding of the influence of flow on seedling scour and burial. As of yet, however, flow and sediment transport in the presence of seedlings are poorly understood. Measurements quantifying the response of topography and flow to the presence of seedlings with differing plant architectures were obtained within a field-scale meandering stream channel with a mobile sand bed (median grain size of 0.7 mm) and full experimental control over sediment and water discharge. Seedlings of Tamarix spp. (tamarisk) and Populus fremontii (cottonwood) with intact roots were installed on a point bar during low flow conditions. Flow rate was then elevated to a constant flood level, while sediment feed rate, plant density, and plant species were varied during each of eight different experimental runs. Flood conditions were maintained long enough for bar topography to reach steady state. The presence of all types of vegetation on the bar decreased the height and lateral extent of dunes migrating across the bar, thereby preventing the development of dunes as the primary mechanism of sediment transport through the bend. Time-averaged bar volume increased from bare-bed conditions when sparse tamarisk, dense tamarisk, or mixed cottonwood and tamarisk seedlings were present on the bar. The presence of dense cottonwood seedlings, however, did not result in an increase in either bar size or height, likely because an increase in steady-state turbulence intensities on the bar when dense cottonwood was present interfered with sediment deposition. Thus, differing plant architecture was an important influence on topographic evolution. In particular, it is possible that the flexibility of tamarisk seedlings causes them to behave analogously to herbaceous vegetation, sheltering the bar surface from turbulent eddies and encouraging deposition. Relationships for the influence of vegetation density and architecture on shear stress and sediment transport are suitable for incorporation into 2-D hydraulic and sediment transport models.

Lightbody, A.; Skorko, K.; Kui, L.; Stella, J. C.; Wilcox, A. C.

2012-12-01

91

Tight Abo gas sands, east-central New Mexico  

Microsoft Academic Search

Red-bed sandstones of the Abo Formation (Lower Permian) currently produce natural gas from the Pecos Slope Abo field in northern Chaves County, New Mexico. The Pecos Slope Abo field is on the northwest shelf of the Permian basin. The tight-sand designation greatly stimulated drilling and over 250 wells have been drilled since field discovery in 1977. Because of low permeability,

Broadhead

1983-01-01

92

Mediative adjustment of river dynamics: The role of chute channels in tropical sand-bed meandering rivers  

NASA Astrophysics Data System (ADS)

This paper examines processes of chute channel formation in four tropical sand-bed meandering rivers; the Strickland and Ok Tedi in Papua New Guinea, the Beni in Bolivia, and the lower Paraguay on the Paraguay/Argentina border. Empirical planform analyses highlight an association between meander bend widening and chute initiation that is consistent with recent physics-based modelling work. GIS analyses indicate that bend widening may be driven by a variety of mechanisms, including scour and cutbank bench formation at sharply-curving bends, point bar erosion due to cutbank impingement against cohesive terrace material, rapid cutbank erosion at rapidly extending bends, and spontaneous mid-channel bar formation. Chute channel initiation is observed to be predominantly associated with two of these widening mechanisms; i) an imbalance between cutbank erosion and point bar deposition associated with rapid bend extension, and ii) bank erosion forced by spontaneous mid-channel bar development. The work extends previous empirical analyses, which highlighted the role of bend extension (elongation) in driving chute initiation, with the observation that the frequency of chute initiation increases once bend extension rates and/or widening ratios exceed a reach-scale threshold. A temporal pattern of increased chute initiation frequency on the Ok Tedi, in response to channel steepening and mid-channel bar development following the addition of mine tailings, mirrors the inter- and intra-reach spatial patterns of chute initiation frequency on the Paraguay, Strickland and Beni Rivers, where increased stream power and sediment load are associated with increased bend extension and chute initiation rates. The process of chute formation is shown to be rate-dependent, and the threshold values of bend extension and widening ratio for chute initiation are shown to scale with measures of river energy, reminiscent of slope-ratio thresholds in river avulsion. Furthermore, Delft3D simulations suggest that chute formation can exert negative feedback on shear stress and bank erosion in the adjacent mainstem bifurcate, such that the process of chute formation may also be rate-limiting. Chute formation is activated iteratively in space and time in response to changes in river energy (and sediment load), predominantly affecting sites of rapid channel elongation, and thereby mediating the river response.

Grenfell, M. C.; Nicholas, A. P.; Aalto, R.

2014-03-01

93

The geomorphic and ecological effectiveness of habitat rehabilitation works: Continuous measurement of scour and fill around large logs in sand-bed streams  

NASA Astrophysics Data System (ADS)

Geomorphologists, ecologists and engineers have all contributed to stream rehabilitation projects by predicting the physical effect of habitat restoration structures. In this study we report the results of a stream rehabilitation project on the Snowy River, SE Australia; that aims to improve fish habitat and facilitate migration associated with scour holes around large wood in the streambed. Whilst engineering models allow us to predict maximum scour, the key management issue here was not the maximum scour depth but whether the holes persisted at a range of flows, and if they were present when fish actually required them. This led to the development of a new method to continuously monitor scour in a sand-bed, using a buried pressure transducer. In this study we monitored fluctuations in the bed level below three large logs (1 m diameter) on the Snowy River. Each log had a different scour mechanism: a plunge pool, a horseshoe vortex (analogous to a bridge pier), and a submerged jet beneath the log. The continuous monitoring demonstrated a complex relationship between discharge and pool scour. The horseshoe vortex pool maintained a constant level, whilst, contrary to expectations, both the plunge pool and the submerged jet pool gradually filled over the 12 months. Filling was associated with the average rise in flows in winter, and occurred despite several freshes and discharge spikes. The plunge pool showed the most variation, with bed levels fluctuating by over 1 m. A key factor in pool scour here may not be the local water depth at the log, but the position of the log in relation to larger scale movements of sand-waves in the stream. These results question assumptions on the relative importance of small floods or channel-maintenance flows that lead to beneficial scour around large wood in sand-bed streams. Further, the continuous measurement of scour and fill around the logs suggested the presence of pool scour holes would have met critical requirements for Australian bass ( Macquaria novemaculeata) during the migration period, whereas less-frequent monitoring typical of rehabilitation trials would have suggested the contrary. The results of this study have demonstrated that geomorphic effectiveness is not always synonymous with biological effectiveness. Whilst physical models emphasise extreme changes, such as maximum scour, the key biological issue is whether scour occurs at the critical time of the life cycle. Continuous measurement of sand levels is an example of a geomorphic technique that will help to develop models that predict biologically meaningful processes, not just extremes.

Borg, Dan; Rutherfurd, Ian; Stewardson, Mike

2007-09-01

94

Characterization of CO2-induced (?) bleaching phenomena in German red bed sediments by combined geochemical and evolved gas analysis  

NASA Astrophysics Data System (ADS)

We investigated varied coloured Buntsandstein and Rotliegend sandstones in Central Germany (Thuringian Vorderrhön, Altmark) by thermogravimetric/pyrolytic (DEGAS- directly coupled evolved gas analysis) and geochemical (ICP-MS/OES) means to evaluate geochemical/mineralogical characteristics of red bed rocks and their presumably altered, bleached modifications. Commonly bleaching of primary red bed sediments is regarded as a result of fluid-rock reactions by the participation of CO2. This study is performed in the framework of the special research program 'GEOTECHNOLOGIEN' (funded by the German Ministry of Education and Research - BMBF) and is part of two BMBF sponsored projects - 'COMICOR', an analogue study on potential effects of CO2-bearing fluids on Buntsandstein and Rotliegend deposits in Hesse and Thuringia and 'CLEAN', an enhanced gas recovery (EGR) pilot project in cooperation with GDF SUEZ E&P Deutschland GmbH. The intention of CLEAN is to evaluate the feasibility of EGR techniques and the suitability of depleted natural gas reservoirs for potential industrial CO2 sequestration projects. According to rock colour variations two slices of handspecimens (M49, A1) were split into 12 and 15 equally sized samples for analytical work. The medium grained Lower Buntsandstein sample M49 from Thuringia is of fluvial origin and partially bleached with transitions from red (unbleached) to light colours (bleached). Bulk rock geochemistry of red bed and bleached subsamples of M49 are almost similar, including rare earth element (REE) content. Only the content of iron and related metals is depleted in bleached samples compared to the red bed types. All PAAS normalized pattern of M49 show positive Eu and slightly negative Ce anomalies, most likely caused by the presence of apatite and illite in the rocks. The degassing behavior observed by DEGAS of M49 subsamples is mainly controlled by the breakdown of sheet silicates, hydroxides and hydrates, as well as of carbonates and sulphates. DEGAS pattern show no obvious systematic differences between the varied coloured zones of this specimen. Sample A1 consists of totally bleached medium grained, lithoclast rich Rotliegend sandstone which was deposited on a flood plain with braided rivers and aeolian dunes. Subsamples of A1 are grouped into three zones - all are bleached, with colours ranging from white to dark grey. Grey and dark grey zones (A1-1 to A1-6, A1-15) are cemented by Ca-rich carbonates and contain microscopically identified bitumina. In contrast the pore space of white zones (A1-7 to A1-14) is filled by anhydrite. These mineralogical differences are also reflected in the bulk rock geochemistry. In comparison to grey rocks white subsamples are depleted in iron and related elements as well as in REEs. Moreover, correlations between rock colour and degassing behavior exist. White samples display typical degassing signatures of sulphates, whereas dark grey zones reveal minor sulphate content, but also the presence of an additional S-species (sulphide) and CO2 (carbonate). Similar features were obtained regarding the specification and abundance of hydrocarbon components. In all samples of A1 methane, ethane and carbonylsulphide were detected, with higher contents in the more whitish parts. In grey rocks an additional, long-chained hydrocarbon component occurs. The relevance of this species is not yet resolved and will be investigated further in more detail. Mass spectrometric gas analytical and related geochemical data confirm major differences in rock composition of Buntsandstein and Rotliegend samples, mainly caused by primary rock composition and by the involvement of variable fluid composition during burial diagenetic alteration. In this study DEGAS was applied for the first time to characterize sandstone geochemistry. Our results constrain that this method might be a complementary analytical tool appropriate for petrological sedimentary research.

Hilse, Ulrike; Goepel, Andreas; Pudlo, Dieter; Heide, Klaus; Gaupp, Reinhard

2010-05-01

95

Laboratory measurements to determine the grain size distribution of a sand-gravel bed surface and substrate: image analysis and CT scanner analysis  

NASA Astrophysics Data System (ADS)

Spatial and temporal changes in the grain size distribution are crucial to describe sediment transport and the related grain size selective processes. Two complimentary laboratory techniques are presented to determine such variations of the grain size distribution of the bed surface and substrate: (1) particle coloring in combination with photogrammetric analysis, and (2) core sampling combined with three-dimensional imaging. The two techniques will be used in later flume experiments that are aimed at studying the response of the river bed to nonsteady boundary conditions. In these flume experiments, the bed surface and substrate grain size distribution needs to be measured using reliable and preferentially rapid techniques. The techniques were evaluated conducting an experiment that partially reproduced the conditions of the later flume experiments. Three nonoverlapping grain size fractions (i.e. within the range of coarse sand to fine gravel) were used and they were painted in different colors. Various mixtures of the three grain size fractions were composed of various color combinations. Patches of the mixtures were installed in a pool. Images were taken of the bed surface and the images were analyzed using an algorithm based on color segmentation. The algorithm provides values of the surface fraction of the bed covered by a certain color (i.e. a size fraction). The influence of water depth on the results of the image analysis was studied. To this end pictures were taken without water and for three water depths. The image analysis results shows that the technique can be used effectively for images of the bed in a flume filled with water. This is beneficiary in applying the technique in the later flume experiments. The second technique comprises core sampling in combination with three-dimensional imaging. Samples taken with tube cores were fixed with wallpaper glue and analyzed using a micro computed tomography scanner (micro CT scanner). The scans provide a three-dimensional image of the sample from which the variation of the grain size distribution over the vertical is derived. The wallpaper glue fixing the sample deals well with wet sediment and does not affect the effectiveness of the x-rays of the CT scanner. The chosen viscosity of the glue makes it adequately infiltrate into the pores of the sample. The core sampling technique combined with the micro CT scanner analysis appears to be suitable to analyze the vertical variation of the grain size distribution in the bed.

Orru, C.; Blom, A.; Uijttewaal, W.

2012-12-01

96

Paleomagnetism and magnetic anisotropy of Cretaceous red beds from the Tarim basin, northwest China: Evidence for a rock magnetic cause of anomalously shallow paleomagnetic inclinations from central Asia  

Microsoft Academic Search

Anomalously shallow paleomagnetic inclinations from Tarim basin red beds have suggested more than 1000 km of northward translation of the Tarim block since the Cretaceous. This is in conflict with geologic observations that indicate only a few hundred kilometers of crustal shortening north of the Tarim basin. To determine whether a rock magnetic effect could be the cause of the

Xiaodong Tan; Kenneth P. Kodama; Hanlin Chen; Dajun Fang; Dongjiang Sun; Yongan Li

2003-01-01

97

Palaeomagnetic study of Cretaceous red beds from the eastern Hindukush ranges, northern Pakistan: palaeoreconstruction of the Kohistan-Karakoram composite unit before the India-Asia collision  

Microsoft Academic Search

We report palaeomagnetic results obtained from Cretaceous red bed samples, collected from the eastern Hindukush mountains, northern Pakistan. Rock magnetic studies revealed specular haematite as the dominant remanence carrier, while pigmentary haematite, magnetite and goethite are responsible for the acquisition of secondary magnetizations. Thermal treatment generally revealed three components of magnetization. The most unstable component (A) was removed between 200°C

Haider Zaman; Masayuki Torii

1999-01-01

98

Sand Wave Study.  

National Technical Information Service (NTIS)

This report will provide further information on the origins of depositional bed forms and their attendant flow regimes. It will focus on sand wave formation, size, and dynamics because the occurrence of these features can have far reaching implications on...

A. DeVisser

1997-01-01

99

Tar sand  

SciTech Connect

Research on tar sand is briefly discussed. The research program supported by the US Department of Energy (DOE) includes a variety of surface extraction schemes. The University of Utah has process development units (PDU) employing fluidized bed, hot, water-assisted, and fluidized-bed/heat-pipe, coupled combustor technology. Considerable process variable test data have been gathered on these systems: (1) a rotary kiln unit has been built recently; (2) solvent extraction processing is being examined; and (3) an advanced hydrogenation upgrading scheme (hydropyrolysis) has been developed. The University of Arkansas, in collaboration with Diversified Petroleum, Inc., has been working on a fatty acid, solvent extraction process. Oleic acid is the solvent/surfactant. Solvent is recovered by adjusting processing fluid concentrations to separate without expensive operations. Western Research Institute has a PDU-scale scheme called the Recycle Oil Pyrolysis and Extraction (ROPE) process, which combines solvent (hot recycle bitumen) and pyrolytic extraction. 14 refs., 19 figs.

McLendon, T.R.; Bartke, T.C.

1990-01-01

100

Geological setting and paleomagnetism of the Eocene red beds of Laguna Brava Formation (Quebrada Santo Domingo, northwestern Argentina)  

NASA Astrophysics Data System (ADS)

The red bed succession cropping out in the Quebrada Santo Domingo in northwestern Argentina had been for long considered as Upper Triassic-Lower Jurassic in age based on weak radiometric and paleontological evidence. Preliminary paleomagnetic data confirmed the age and opened questions about the nature of fossil footprints with avian features discovered in the section. Recently the stratigraphic scheme was reviewed with the identification of previously unrecognized discontinuities, and a radiometric dating obtained in a tuff, indicated an Eocene age for the Laguna Brava Formation and the fossil bird footprints, much younger than the previously assigned. We present a detailed paleomagnetic study interpreted within a regional tectonic and stratigraphic framework, looking for an explanation for the misinterpretation of the preliminary paleomagnetic data. The characteristic remanent magnetizations pass a tilt test and a reversal test. The main magnetic carrier is interpreted to be low Ti titanomagnetites and to a lesser extent hematite. The characteristic remanent magnetization would be essentially detrital. The obtained paleomagnetic pole (PP) for the Laguna Brava Formation has the following geographic coordinates and statistical parameters: N = 29, Lon. = 184.5° E, Lat. = 75.0° S, A95 = 5.6° and K = 23.7. When this PP is compared with another one with similar age obtained in an undeformed area, a declination anomaly is recognized. This anomaly can be interpreted as Laguna Brava Formation belonging to a structural block that rotated about 16° clockwise along a vertical axis after about 34 Ma. This block rotation is consistent with the regional tectonic framework, and would have caused the fortuitous coincidence of the PP with Early Jurassic poles. According to the interpreted magnetostratigraphic correlation, the Laguna Brava Formation would have been deposited during the Late Eocene with a mean sedimentation rate of about 1.4 cm per thousand years, probably in relation to the onset of the Andean deformation.

Vizán, H.; Geuna, S.; Melchor, R.; Bellosi, E. S.; Lagorio, S. L.; Vásquez, C.; Japas, M. S.; Ré, G.; Do Campo, M.

2013-01-01

101

Anisotropy of thermoremanent magnetisation of Cryogenian glaciogenic and Ediacaran red beds, South Australia: Neoproterozoic apparent or true polar wander?  

NASA Astrophysics Data System (ADS)

Determining the effects of compaction-related inclination shallowing of remanence directions is crucial for ascertaining the validity of low palaeolatitudes for Neoproterozoic red beds in South Australia that are central to the debate concerning low-latitude Proterozoic glaciation. The inclination correction (or flattening) factor, f, is defined as tan(ID)/tan(IF), where ID and IF are the inclinations of the measured detrital remanence and the ancient inducing field, respectively. The anisotropy can be estimated using anisotropy of magnetic susceptibility and the anisotropy of high-field isothermal remanence (hf-AIR). The elongation-inclination (E-I) method has also been used to infer inclination shallowing. We add the anisotropy of thermoremanent magnetisation (ATR) to these methods. For the late Cryogenian Elatina Formation arenites, which constitute the bulk of the Elatina data set, the inclination correction using f = 0.738 derived from ATR increases the palaeolatitude of the Elatina Formation from 6.5 ± 2.2° to 8.8 ± 3.2°, which confirms that the Elatina glaciation occurred near the palaeoequator. Inclination corrections for the Ediacaran argillaceous Brachina and Wonoka formations, using f = 0.35-0.38 derived from ATR, are significantly greater than for the more arenaceous Elatina Formation, which increases their palaeolatitudes from ~ 12° to ~ 30°. Carbonates from the basal Ediacaran Nuccaleena Formation yielded f = 0.8 from ATR, which represents only a small palaeolatitude correction from 19° to 23°. The anisotropy results imply that the characteristic remanent magnetisations carried by all these units were acquired early as depositional remanent magnetisations, essentially at the time of deposition. The shift of the palaeopoles from argillaceous units indicating significantly higher palaeolatitudes introduces a distinctive loop into the late Cryogenian-Ediacaran-Cambrian pole path for Australia. This loop shows similarities with the North American pole path for this period, for which true polar wander (TPW) has been inferred. However, until ages of Neoproterozoic strata in South Australia are better constrained uncertainty persists on whether the similarities of the Australian and North American pole paths reflect TPW.

Schmidt, Phillip W.; Williams, George E.

2013-11-01

102

Deceleration of projectiles in sand  

NASA Astrophysics Data System (ADS)

Penetration of projectiles was measured for hemispherical and conical nose shapes penetrating granular media. Targets were beds of Ottawa sand and Eglin sand. Projectiles were rigid metals. Experimental parameters that were varied included velocity (from 300 to 600 m/s), nose shape, sand density, and scale (from 5 mm to 20 mm). Strong evidence for scale effects is found: 5 mm diameter projectiles are less effective penetrators than 12.5, 15, or 20 mm diameter penetrators.

Bless, Stephan; Cooper, William; Watanabe, Keiko; Peden, Robert

2012-03-01

103

Mystery Sand  

NSDL National Science Digital Library

In this activity, learners play with surprising sand that doesnât get wet! Learners explore how water behaves differently when it comes in contact with "magic sand" and regular sand. Learners learn about the hydrophobic properties of "magic sand." Use this activity to talk about how many materials behave differently at the nanoscale.

Sciencenter

2012-01-01

104

Paleomagnetic data from Upper Cretaceous Red Beds, Northwest Vietnam (Song Da Terrane), and Their Bearing on the Extrusion History of Indochina and Deformation Along its Margins  

NASA Astrophysics Data System (ADS)

Northwest Vietnam mainly consists of the Song Da terrane, which is bounded to the east by the NW-oriented Ailao Shan/Red River (ASRR) fault system, interpreted to be the southwest margin of the South China Block, and the NW-oriented Song Ma fault. The northern termination of the Song Da terrane is considered to be where the NE-oriented, right lateral Dien Bien Phu fault intersects the ASRR. Whether the Song Da terrane is part of the extruded Indochina Block, paleomagnetic data from which suggest some 10°+ southward latitudinal displacement, can be evaluated with paleomagnetic data from rocks of the appropriate age. Our paleomagnetic sampling concentrated on the Upper Cretaceous Yen Chau Formation, which unconformably overlies Paleozoic and Triassic sedimentary rocks. The Yen Chau Formation is locally up to about 1300 m thick, and is characterized by medium to thick bedded, coarse to fine-grained sandstones and siltstones, all of which are partially cemented by hematite. Samples were collected from 10 localities using a portable drill, with 6 to 19 sites collected per locality, and 7 to 15 samples collected from each site. This approach allows evaluation of the integrity of the remanence at the locality level, where, presumably, considerable time is recorded in each section. Each locality is a homoclinal road cut exposure, with bedding dips varying from sub-horizontal to moderately overturned. NRM intensities range from about 0.7 mA/m to about 25 mA/m; values which are relatively low in comparison to many red beds. A varied response to alternating field (AF) demagnetization indicates that magnetite carries a considerable (over 50 percent) of the remanence; the finest grained samples of relatively high NRM intensity reveal little response to AF treatment, indicating a dominance by hematite, as also supported by three-component IRM thermal demagnetization. Samples with the highest NRM intensities and the least contribution by magnetite respond favorably to thermal demagnetization, with full remanence unblocking by about 685°C, and yield characteristic magnetization directions of north-northeast to northeast declination and moderate positive inclination (about 30 to 35°). Our preliminary results are comparable to those of Takemoto et al. (2005, EPSL, 229, 273- 285) and we tentatively conclude that there has been no significant latitudinal translation of the Song Da terrane, since the Early Cretaceous, with respect to the South China Block. We continue to explore the possibility of local scale, vertical axis rotation of parts of the Song Da terrane. Extrusion of the Indochina Block, in association with its own style of internal deformation, appears to have been facilitated by displacement along structures west of the Song Ma fault.

Geissman, J. W.; Pho, N.; Burchfiel, B.; Muggleton, S. R.

2008-12-01

105

Gas percolation through sand  

NASA Astrophysics Data System (ADS)

Previous research has determined the shock properties of quartz sand. The effect of the physical processes occurring with varying moisture content and particle size were shock presented. In this study the same quartz sand, in a column is subjected to blast waves over a range of pressure. The diagnostics used are pressure sensors and high-speed photography. The effect of grain size on propagation time and the effect of moisture content are determined. Aspects of particle and liquid movement are also discussed. While the velocity of the percolation through the bed is primarily controlled by grain size the effect of moisture and liquids reveals a more complex dependence.

Proud, W. G.

2014-05-01

106

A playa deposit of pre-Yellow Sands age (upper Rotliegend\\/Weissliegend) in the Permian of northeast England  

Microsoft Academic Search

A complexly interbedded thin succession of sandstone, siltstone and mudstone beneath the Permian Yellow Sands Formation (upper Rotliegend\\/Weissliegend) was cored in a borehole 11 km off the coast of northeast England. The cored strata rest unconformably on fissured Westphalian B mudstone and mainly comprise low-dipping fine- to coarse-grained grey sandstone with unevenly spaced thinner dark-red to grey mudstone beds and

Brian R. Turner; Denys B. Smith

1997-01-01

107

Sand Drains.  

National Technical Information Service (NTIS)

Explains the sand drain method of consolidating swampy areas for the construction of highways. Uses animation and scenes of an actual project to show preparation of the site, driving the sand drains, placing the control devices and overload, final prepara...

1994-01-01

108

Integration of bed characteristics, geochemical tracers, current measurements, and numerical modeling for assessing the provenance of beach sand in the San Francisco Bay coastal system  

USGS Publications Warehouse

Over 150 million m3 of sand-sized sediment has disappeared from the central region of the San Francisco Bay Coastal System during the last half century. This enormous loss may reflect numerous anthropogenic influences, such as watershed damming, bay-fill development, aggregate mining, and dredging. The reduction in Bay sediment also appears to be linked to a reduction in sediment supply and recent widespread erosion of adjacent beaches, wetlands, and submarine environments. A unique, multi-faceted provenance study was performed to definitively establish the primary sources, sinks, and transport pathways of beach-sized sand in the region, thereby identifying the activities and processes that directly limit supply to the outer coast. This integrative program is based on comprehensive surficial sediment sampling of the San Francisco Bay Coastal System, including the seabed, Bay floor, area beaches, adjacent rock units, and major drainages. Analyses of sample morphometrics and biological composition (e.g., Foraminifera) were then integrated with a suite of tracers including 87Sr/86Sr and 143Nd/144Nd isotopes, rare earth elements, semi-quantitative X-ray diffraction mineralogy, and heavy minerals, and with process-based numerical modeling, in situ current measurements, and bedform asymmetry to robustly determine the provenance of beach-sized sand in the region.

Barnard, Patrick L.; Foxgrover, Amy C.; Elias, Edwin P. L.; Erikson, Li H.; Hein, James R.; McGann, Mary; Mizell, Kira; Rosenbauer, Robert J.; Swarzenski, Peter W.; Takesue, Renee K.; Wong, Florence L.; Woodrow, Donald L.

2013-01-01

109

Influence of riparian vegetation on channel widening and subsequent contraction on a sand-bed stream since European settlement: Widden Brook, Australia  

NASA Astrophysics Data System (ADS)

Widden Brook in the Hunter Valley, Australia, was first settled by Europeans in 1831 and had widened substantially by the 1870s due to frequent floods during a flood-dominated regime impacting on highly disturbed banks whose riparian trees had been either ringbarked or cleared, and whose understorey had been grazed. Catastrophic floods in 1950 (many), two in August 1952 and one in February 1955 effected the final phase of channel widening at the onset of a second flood-dominated regime more than half a century after the initial widening. Contraction has been active since 1963 by a combination of five biogeomorphic processes. Firstly, rapid channel widening, migration and cutoffs totally reworked the pre-European floodplain and were followed by active floodplain formation. Initial bar formation was replaced by sand splay and overbank deposition which constructed a new floodplain and narrower channel. Secondly, overwidened channel segments that were produced by the catastrophic 1955 flood have contracted since 1963 by the formation of up to four bank-attached, discontinuous benches below the floodplain. Each bench has a bar nucleus of pebbly coarse sand overlain by stratified fine-medium sand and mud. Colonisation by River Sheoaks (Casuarina cunninghamiana subsp. cunninghamiana) or grasses (Cynodon dactylon, Paspalum distichum, Pennisetum clandestinum) is important in converting bars to benches. Thirdly, narrower segments which developed since 1963 have contracted by small-scale accretion on both banks. These deposits are steeply dipping, interbedded sand and mud trapped by stoloniferous and rhizomatous grasses (C. dactylon, P. distichum, P. clandestinum) which also rapidly stabilise the deposits. Fourthly, rare laterally migrating, small radius bends have contracted by recent point bar formation greatly exceeding cutbank recession rates. Point bar formation is controlled by secondary currents producing inclined stratified coarse sands without the influence of vegetation. Lastly, rare, overwidened, non-migrating, large radius bends have greatly contracted by the infilling of dissecting chutes across the convex bank. Establishment of stoloniferous and rhizomatous clonal grasses (Phragmites australis, C. dactylon, P. distichum, P. clandestinum) is important in inducing sedimentation of the chutes. Contraction has produced a much narrower channel than the design width between river training fences which were installed progressively between the 1960s and 1990s. The recent flood history of Widden Brook has not included any catastrophic floods of a size similar to February 1955. Our work demonstrates that both trees and grasses can be associated with narrower channel widths and that the causal link between width and vegetation type is more complex than usually acknowledged.

Erskine, Wayne; Keene, Annabelle; Bush, Richard; Cheetham, Michael; Chalmers, Anita

2012-04-01

110

Heat transfer in a crater bed  

Microsoft Academic Search

The aim of this work is to study heat transfer in a laboratory scale crater bed, which was set up from a cylindrical acrylic\\/quartz tube, using sand as the bed particle. The bed employs a downward gas jet from a nozzle which causes the particles to ascend fountain-like into the freebroad, leaving a crater on the bed surface. After reaching

Pawin Chaivatamaset; Suvit Tia

2007-01-01

111

Why are ripples absent in coarse sands?  

NASA Astrophysics Data System (ADS)

Current ripples are perhaps the most abundant and common bedform and sedimentary structure in contemporary and ancient sediments, with their stability field being dependent on the applied bed shear stress and grain size. The ripple stability field begins to narrow in medium sand with ripples ceasing to exist in sands coarser than c. 0.7mm diameter. Leeder (1980) proposed that the absence of ripples in coarse sands is linked to the influence of increasing grain roughness that strengthens vertical mixing of fluid near the bed, and thereby disrupts flow separation over bed defects from which ripples normally propagate. In this paper, we use a novel thin (5mm wide) flume to investigate the dynamics of bedforms developed in a very coarse sand and use PIV to detail the dynamics of flow associated with the initial bedforms developed in this sand. We highlight the irregular wavelength, height and migration characteristics of these bedforms and contrast this with ripples developed in a medium sand. Furthermore, we utilize the near-bed PIV data to examine vertical flow velocities and the possible role of hyporheic flow upwelling in the bedform leeside. Such hyporheic flow, induced by pressure gradients established around the bedform, can lead to significant modifications to the leeside flow separation zone that may be contribute to the absence of current ripples in coarse sands. Reference Leeder, M.R. 1980 On the stability of lower stage plane beds and the absence of ripples in coarse sands, J. Geol. Soc. London, 137, 423-30.

Best, J.; Barros, J.; Blois, G.; Christensen, K. T.

2013-12-01

112

Discovering Sand and Sand Paintings  

NSDL National Science Digital Library

This activity blends social studies and art with math and science. First, students will explore the visible characteristics of sand, and then they will make Navajo-style sand paintings with paper, glue, and colored sand. In the process, they will hone the

Eichinger, John

2009-05-30

113

Facies sequence of Triassic-Jurassic red beds in the Sierra Madre Oriental (NE Mexico) and its relation to the early opening of the Gulf of Mexico  

NASA Astrophysics Data System (ADS)

The configuration of Upper Triassic grabens in the Gulf of Mexico rift system is pointed out by the suture zones of late Palaeozoic plate convergence. Rifting particularly started on both sides of the ancient magmatic arc. The taphrogenic red beds of the Huizachal Formation in the Sierra Madre Oriental represent the western parts of this system. The early syn-rift sediments are characterized by fining upward cycles of a fluvial environment with a low-sinuosity channel pattern. Later on, decreasing of relief intensity caused the change to a rather meandering system. Climate was evidently semiarid during that time. The petrographic composition of the clastic rocks suggests a nearby sedimentary-metamorphic basement. The transition to early post-rift sediments is marked by an angular unconformity. Its formation approximately coincides with the first emplacement of oceanic crust in the central parts of the Gulf basin. The early post-rift sediments of the La Joya Formation show, within a single fining upward megacycle, the transition from terrestrial to marine conditions that persisted up to the beginning of Cenozoic time.

Michalzik, Dieter

1991-05-01

114

Paleomagnetism of the Middle-Late Jurassic to Cretaceous red beds from the Peninsular Thailand: Implications for collision tectonics  

NASA Astrophysics Data System (ADS)

Jurassic to Cretaceous red sandstones were sampled at 33 sites from the Khlong Min and Lam Thap formations of the Trang Syncline (7.6°N, 99.6°E), the Peninsular Thailand. Rock magnetic experiments generally revealed hematite as a carrier of natural remanent magnetization. Stepwise thermal demagnetization isolates remanent components with unblocking temperatures of 620-690 °C. An easterly deflected declination ( D = 31.1°, I = 12.2°, ?95 = 13.9°, N = 9, in stratigraphic coordinates) is observed as pre-folding remanent magnetization from North Trang Syncline, whereas westerly deflected declination ( D = 342.8°, I = 22.3°, ?95 = 12.7°, N = 13 in geographic coordinates) appears in the post-folding remanent magnetization from West Trang Syncline. These observations suggest an occurrence of two opposite tectonic rotations in the Trang area, which as a part of Thai-Malay Peninsula received clockwise rotation after Jurassic together with Shan-Thai and Indochina blocks. Between the Late Cretaceous and Middle Miocene, this area as a part of southern Sundaland Block experienced up to 24.5° ± 11.5° counter-clockwise rotation with respect to South China Block. This post-Cretaceous tectonic rotation in Trang area is considered as a part of large scale counter-clockwise rotation experienced by the southern Sundaland Block (including the Peninsular Malaysia, Borneo and south Sulawesi areas) as a result of Australian Plate collision with southeast Asia. Within the framework of Sundaland Block, the northern boundary of counter-clockwise rotated zone lies between the Trang area and the Khorat Basin.

Yamashita, Itaru; Surinkum, Adichat; Wada, Yutaka; Fujihara, Makoto; Yokoyama, Masao; Zaman, Haider; Otofuji, Yo-ichiro

2011-02-01

115

Sedimentology of freshwater lacustrine shoreless in the Eocene Scheggs Bed of the Tipton Tongue of the Green River Formation, Sand Wash Basin, Northwest Colorado  

SciTech Connect

In this paper two freshwater shorelines, 40-274 ft thick, were investigated in the Scheggs Bed along Hardgrove Rim, 8 mi north of Maybell, Colorado. The rocks comprising the shorelines consist of interbedded quartzose sandstone, conglomerate, siltstone, shale, oil shale, carbonaceous shale, and coal. The shorelines are divisible into fluvial channel, mudflat, swamp, strandline, nearshore, and offshore lithofacies, which are identified by their stratigraphic positions, characteristic lithologies, and sedimentary structures. A columnar section is presented as a model for similar deposition in other members of the Green River Formation.

Roehler, H.W.

1990-12-01

116

The palaeomagnetism of (Mesoproterozoic) Eriksfjord Group red beds, South Greenland: multiphase remagnetization during the Gardar and Grenville episodes  

NASA Astrophysics Data System (ADS)

The Eriksfjord Group comprises ~3000 m of lavas and sediments rapidly deposited in a rift which developed within an Andean-type batholith in juxtaposition to the southern margin of the Laurentian Shield in South Greenland at ca. 1300 Ma. The lavas have been shown to preserve a detailed record of the geomagnetic field at the time of eruption, incorporating normal, reversed and transitional directions. This study has examined the magnetic properties of the intervening red sediments. They are found to possess a diagenetic remanence imparted by mediating fluids at later times. The impact of diagenesis is stratigraphically controlled: the base of the rift infill has magnetizations partially resident in magnetite which are either unstable to thermal cleaning or record a single polarity `B' magnetization (D/I = 284/67°, 31 samples, ?95 = 5.5°, palaeopole at 244.1°E, 47.5°N, dp/dm = 7.5/9.1° ). This corresponds in polarity, and closely in direction, to remanence observed in mid-Gardar gabbro giant dykes and dyke swarms emplaced along the axis of the rift system at ca. 1160 Ma the causative diagenetic magnetite appears to have grown from hydrothermal systems motivated by this magmatism in a sealed reservoir setting within the lower part of the rift infill. The Ilímaussaq alkaline igneous complex was emplaced into the southern extension of the rift at ca. 1130 Ma and possesses a dual polarity magnetization (D/I = 327/81°, ?95 = 6.4°, 10 sites). Eriksfjord lavas within the thermal aureole are overprinted to varying degrees by comparable magnetizations with steep inclinations. The mean pole position (283°E, 71°N, dp/dm = 12/12° ) lies near the apex of an apparent polar wander loop incorporating the Gardar Track (ca. 1300-1140 Ma) and the Keweenawan Track (ca. 1115-1050 Ma). Magnetizations in the Eriksfjord sedimentary succession have not been significantly reset by emplacement of the Ilímaussaq complex, but higher levels of the rift infill are dominated by an `A' magnetization (D/I = 305/34°, ?95 = 4.3°, 57 samples, palaeopole at 202.1°E, 32.4°N, dp/dm = 2.8/4.9° ) resident in haematite. The pole position does not correspond with any part of the Gardar Track, but does correlate with the return Keweenawan Track at ca. 1090 Ma, close to the time of Grenville orogenesis along the bordering southeastern margin of the Laurentian Shield. This remanence is attributed to diagenesis during extensional tectonism linked to the collapse of the Grenville Orogen formerly sited 100-200 km to the south.

Piper, J. D. A.; Thomas, D. N.; Share, S.; Rui, Zhang Qi

1999-03-01

117

Tar sands  

Microsoft Academic Search

The four largest oil sand deposits contain over 90% of the world's known heavy oil. The total heavy oil and bitumen in place, estimated at nearly 6 trillion barrels is almost entirely concentrated in western Canada, principally Alberta, and eastern Venezuela. The known tar sand resource in the United States consists of about 550 occurrences located in 22 states. The

Wennekers; J. H. N

1981-01-01

118

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

119

SHRIMP U-Pb ages of xenotime and monazite from the Spar Lake red bed-associated Cu-Ag deposit, western Montana: Implications for ore genesis  

USGS Publications Warehouse

Xenotime occurs as epitaxial overgrowths on detrital zircons in the Mesoproterozoic Revett Formation (Belt Supergroup) at the Spar Lake red bed-associated Cu-Ag deposit, western Montana. The deposit formed during diagenesis of Revett strata, where oxidizing metal-bearing hydrothermal fluids encountered a reducing zone. Samples for geochronology were collected from several mineral zones. Xenotime overgrowths (1–30 ?m wide) were found in polished thin sections from five ore and near-ore zones (chalcocite-chlorite, bornite-calcite, galena-calcite, chalcopyrite-ankerite, and pyrite-calcite), but not in more distant zones across the region. Thirty-two in situ SHRIMP U-Pb analyses on xenotime overgrowths yield a weighted average of 207Pb/206Pb ages of 1409 ± 8 Ma, interpreted as the time of mineralization. This age is about 40 to 60 m.y. after deposition of the Revett Formation. Six other xenotime overgrowths formed during a younger event at 1304 ± 19 Ma. Several isolated grains of xenotime have 207Pb/206Pb ages in the range of 1.67 to 1.51 Ga, and thus are considered detrital in origin. Trace element data can distinguish Spar Lake xenotimes of different origins. Based on in situ SHRIMP analysis, detrital xenotime has heavy rare earth elements-enriched patterns similar to those of igneous xenotime, whereas xenotime overgrowths of inferred hydrothermal origin have hump-shaped (i.e., middle rare earth elements-enriched) patterns. The two ages of hydrothermal xenotime can be distinguished by slightly different rare earth elements patterns. In addition, 1409 Ma xenotime overgrowths have higher Eu and Gd contents than the 1304 Ma overgrowths. Most xenotime overgrowths from the Spar Lake deposit have elevated As concentrations, further suggesting a genetic relationship between the xenotime formation and Cu-Ag mineralization.

Aleinikoff, John N.; Hayes, Timothy S.; Evans, Karl V.; Mazdab, Frank K.; Pillers, Renee M.; Fanning, C. Mark

2012-01-01

120

The origin, classification and modelling of sand banks and ridges  

Microsoft Academic Search

Sand banks and elongated sand ridges occur in many coastal and shelf seas where there is abundant sand and where the currents are strong enough to move sediment, but they have a wide variety of forms. Their generation requires a source of mobile sediment, either from the local sea bed, or from coast erosion. Most appear to have been created

Keith R Dyer; David A Huntley

1999-01-01

121

Sands-on Learning.  

ERIC Educational Resources Information Center

Provides information for the development of a lesson which teaches students about sand, discusses facts about sands, sand studies, life in the sands, and sand activities. Includes diagrams showing the range in sand grain shape, formation of sand ripples, and sand samples from around the world. (RT)

Vandervoort, Frances S.

1989-01-01

122

Deceleration of Projectiles in Sand  

NASA Astrophysics Data System (ADS)

Deceleration of projectiles has been measured for hemispherical and conical nose shapes penetrating granular media. Targets were beds of Ottawa sand and Eglin sand. The velocity range extended up to 600 m/s. Projectiles were rigid metals. Deceleration was measured by conventional time-of-arrival screens plus several innovative techniques: embedded EM coils, embedded optical fibers, and a photonic Doppler velocimeter (PDV), which observed the rear surface of the penetrator. Experimental parameters that were varied included velocity (from 300 to 600 m/s), sand density, and scale (from 5 mm to 25 mm). In this paper we will compare these various measurement techniques and we will show how the cavity geometry (cavitation and crushed veins of sand) and retarding stress (MdV/dt)/Avary with velocity, scale, and density.

Bless, Stephan; Cooper, William; Stone, Zach; Watanabe, Keiko; Peden, Robert

2011-06-01

123

Dual Fluidized Bed Biomass Gasification  

SciTech Connect

The dual fluidized bed reactor is a recirculating system in which one half of the unit operates as a steam pyrolysis device for biomass. The pyrolysis occurs by introducing biomass and steam to a hot fluidized bed of inert material such as coarse sand. Syngas is produced during the pyrolysis and exits the top of the reactor with the steam. A crossover arm, fed by gravity, moves sand and char from the pyrolyzer to the second fluidized bed. This sand bed uses blown air to combust the char. The exit stream from this side of the reactor is carbon dioxide, water and ash. There is a second gravity fed crossover arm to return sand to the pyrolysis side. The recirculating action of the sand and the char is the key to the operation of the dual fluidized bed reactor. The objective of the project was to design and construct a dual fluidized bed prototype reactor from literature information and in discussion with established experts in the field. That would be appropriate in scale and operation to measure the relative performance of the gasification of biomass and low ranked coals to produce a high quality synthesis gas with no dilution from nitrogen or combustion products.

None

2005-09-30

124

The extraction of bitumen from western tar sands. Annual report, July 1990--July 1991  

SciTech Connect

Contents of this report include the following: executive summary; characterization of the native bitumen from the Whiterocks oil sand deposit; influence of carboxylic acid content on bitumen viscosity; water based oil sand separation technology; extraction of bitumen from western oil sands by an energy-efficient thermal method; large- diameter fluidized bed reactor studies; rotary kiln pyrolysis of oil sand; catalytic upgrading of bitumen and bitumen derived liquids; ebullieted bed hydrotreating and hydrocracking; super critical fluid extraction; bitumen upgrading; 232 references; Appendix A--Whiterocks tar sand deposit bibliography; Appendix B--Asphalt Ridge tar sand deposit bibliography; and Appendix C--University of Utah tar sands bibliography.

Oblad, A.G.; Bunger, J.W.; Deo, M.D.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1992-04-01

125

Tar sands  

SciTech Connect

The four largest oil sand deposits contain over 90% of the world's known heavy oil. The total heavy oil and bitumen in place, estimated at nearly 6 trillion barrels is almost entirely concentrated in western Canada, principally Alberta, and eastern Venezuela. The known tar sand resource in the United States consists of about 550 occurrences located in 22 states. The total oil in place in 39 of these occurrences is estimated to be between 23.7 billion and 32.7 billion barrels. At least 90% of this resource is located in Utah. Other significant deposits are in Texas, New Mexico, California, and Kentucky. Bituminous sand deposits and petroleum-impregnated rocks are found in Malagasy, Albania, Rumania, the USSR, and Trinidad. 4 figures, 2 tables. (DP)

Wennekers, J.H.N.

1981-10-01

126

Defrosting Sand  

NASA Technical Reports Server (NTRS)

2 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a patch of frost-covered, dark sand that, at the time the picture was acquired in June 2005, had begun to defrost. The frost is carbon dioxide. Dunes and other patches of sand are usually the first polar features to develop dark spots as the frost begins to sublime away.

Location near: 78.9oS, 80.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

2005-01-01

127

Sand Babies  

NSDL National Science Digital Library

In this math lesson, learners explore and investigate measurement using standard and non-standard units. First, learners round their birth weight to the nearest pound and construct a bar graph displaying the weights of the entire group. Next, learners measure and place enough sand into a plastic bag to equal their birth weight. With construction paper, crayons and markers, they draw a head, arms, and legs and turn the bags into sand babies. At centers, learners also investigate other types of measurements using non-standard plastic links to measure parts of their body and square tiles to measure the area of a footprint.

Pbs

2012-01-01

128

Beach Sand  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about weathering, erosion, deposition, and landforms. It is designed to determine if students recognize that sand on a beach may have come from distant mountains and landforms as a result of the weathering of rock, subsequent erosion, and deposition.

Eberle, Francis; Farrin, Lynn; Keeley, Page

2005-01-01

129

Tar sands development  

Microsoft Academic Search

Tar sands (also known as oil sands and bituminous sands) are sand deposits which are impregnated with dense viscous petroleum. Ultimate world reserves of bitumen in tar sands are about equal to ultimate reserves of crude oil in the U.S. However, the only tar-sand deposit of present commercial importance is in the Athabasca area of Alberta, Canada. The pioneer venture

1973-01-01

130

Defrosting Sand  

NASA Technical Reports Server (NTRS)

19 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark spots formed in carbon dioxide frost that covers the surfaces of patches of sand in the south polar region. As spring arrived this year in the martian southern hemisphere, so began the annual defrosting process. The fact that sand dunes begin to defrost earlier than other surfaces, and that the defrosting process involves the formation of spots like these, has been known since the earliest days of the MGS mission.

Location near: 66.8oS, 15.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

2005-01-01

131

SLUDGE DEWATERING AND DRYING ON SAND BEDS  

EPA Science Inventory

Dewatering of water and wastewater treatment sludges was examined through mathematical modeling and experimental work. The various components of the research include: (1) chemical analyses of water treatment sludges, (2) drainage and drying studies of sludges, (3) a mathematical ...

132

Bed Bugs  

MedlinePLUS

... pest control company. Top of page Bed Bug Biology Knowing what to look for is the first ... 2011: Bed Bug Grants Awarded Bed Bugs - Importance, Biology, and Control Strategies (Armed Forces Pest Management Board) ...

133

Occurrence of Radium-224, Radium-226 and Radium-228 in Water from the Vincentown and Wenonah-Mount Laurel Aquifers, the Englishtown Aquifer System, and the Hornerstown and Red Bank Sands, Southwestern and South-Central New Jersey  

USGS Publications Warehouse

This investigation is the first regionally focused study of the presence of natural radioactivity in water from the Vincentown and Wenonah-Mount Laurel aquifers, Englishtown aquifer system, and the Hornerstown and Red Bank Sands. Geologic materials composing the Vincentown and Wenonah-Mount Laurel aquifers and the Hornerstown and Red Bank Sands previously have been reported to contain radioactive (uranium-enriched) phosphatic strata, which is common in deposits from some moderate-depth coastal marine environments. The decay of uranium and thorium gives rise to natural radioactivity and numerous radioactive progeny, including isotopes of radium. Naturally occurring radioactive isotopes, especially those of radium, are of concern because radium is a known human carcinogen and ingestion (especially in water used for drinking) can present appreciable health risks. A regional network in southwestern and south-central New Jersey of 39 wells completed in the Vincentown and Wenonah-Mount Laurel aquifers, the Englishtown aquifer system, and the Hornerstown and Red Bank Sands was sampled for determination of gross alpha-particle activity; concentrations of radium radionuclides, major ions, and selected trace elements; and physical properties. Concentrations of radium-224, radium-226, and radium-228 were determined for water from 28 of the 39 wells, whereas gross alpha-particle activity was determined for all 39. The alpha spectroscopic technique was used to determine concentrations of radium-224, which ranged from less than 0.5 to 2.7 pCi/L with a median concentration of less than 0.5pCi/L, and of radium-226, which ranged from less than 0.5 to 3.2 pCi/L with a median concentration of less than 0.5 pCi/L. The beta-counting technique was used to determine concentrations of radium-228. The concentration of radium-228 ranged from less than 0.5 to 4.3 pCi/L with a median of less than 0.5. Radium-228, when quantifiable, had the greatest concentration of the three radium radioisotopes in 9 of the 12 samples (75 percent). The concentration of radium-224 exceeded that of radium-226 in five of the six (83 percent) samples when both were quantifiable. The radium concentration distribution differed by aquifer, with the highest Ra-228 concentrations present in the Englishtown aquifer system and the highest Ra-226 concentrations present in the Wenonah-Mount Laurel aquifer. Radium-224 generally contributed a considerable amount of gross alpha-particle activity to water produced from all the sampled aquifers, but was not the dominant radionuclide as it is in water from the Kirkwood-Cohansey aquifer system, nor were concentrations greater than 1 pCi/L of radium-224 widespread. Gross alpha-particle activity was found to exceed the U.S Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 15 pCi/L in one sample (16 pCi/L) from the Vincentown aquifer. A greater part of the gross alpha-particle activity in water from the Wenonah-Mount Laurel aquifer resulted from the decay of Ra-226 than did the gross alpha-particle activity in the other sampled aquifers; this relation is consistent with the concentration distribution of the Ra-226 itself. Concentrations of radium-224 correlate strongly with those of both radium-226 and radium-228 (Spearman correlation coefficients, r, +0.86 and +0.66, respectively). The greatest concentrations of radium-224, radium-226, and radium-228 were present in the most acidic ground water. All radium-224, radium-226, and radium-228 concentrations greater than 2.5 pCi/L were present in ground-water samples with a pH less than 5.0. The presence of combined radium-226 and radium-228 concentrations greater than 5 pCi/L in samples from the Vincentown and Wenonah-Mount Laurel aquifers and the Englishtown aquifer system was not nearly as common as in samples from the Kirkwood-Cohansey aquifer system, likely because of the slightly higher pH of water from these aquifers relative to that of Kirkwood-Cohansey aqu

dePaul, Vincent T.; Szabo, Zoltan

2007-01-01

134

Predicted and observed cyclic performance of piles in calcareous sand  

Microsoft Academic Search

The performance of small-scale model piles jacked into calcareous sand and tested under cyclic axial loadings is presented in this paper. The calcareous sand beds used for the tests have been prepared from reconstituted soil that has been consolidated under different overburden pressures using a test vessel of special design. The study is focused on the accumulation of permanent displacement

Riadh H. Al-Douri; Harry G. Poulos

1995-01-01

135

Sand Diver  

NASA Astrophysics Data System (ADS)

A few years ago, I was preparing to teach a summer enrichment program for middle school students at the University of Wisconsin-Stout. With swimming on the minds of most kids during the summer, I thought buoyancy would be a fun topic to discuss. An interesting way to introduce this concept is by discussing the beer-drinking balloonist who, in a lawn chair, floated to 11,000 feet above Los Angeles in 1997. However, I needed a hands-on project and was not about to go purchase some lawn chairs to duplicate this experiment. A simple submersible called the ``Sand Diver'' was designed and is now used as a hands-on activity for my introductory physics course.

Scott, Alan J.

2005-01-01

136

The extraction of bitumen from western oil sands. Final report, July 1989--September 1993  

SciTech Connect

Research and development of surface extraction and upgrading processes of western tar sands are described. Research areas included modified hot water, fluidized bed, and rotary kiln pyrolysis of tar sands for extraction of bitumen. Bitumen upgrading included solvent extraction of bitumen, and catalytic hydrotreating of bitumen. Characterization of Utah tar sand deposits is also included.

Oblad, A.G.; Bunger, J.W.; Dahlstrom, D.A.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1994-03-01

137

A Comparison between Passive Regenerative and Active Fluidized Bed Thermal Energy Storage Systems  

NASA Astrophysics Data System (ADS)

Active Fluidized Bed Thermal Energy Storage (sandTES) offers a promising alternative to the current state of the art thermal energy storages (TES), such as active TES based on molten salt or passive TES (Regenerators) realised as a porous packing of ceramics. The characteristic of a sandTES system applying sand in an active TES using a fluidized bed heat exchanger (HEX) is explained. The exergetic performance of a sandTES is compared to a passive Regenerator.

Haider, M.; Schwaiger, K.; Holzleithner, F.; Eisl, R.

2012-11-01

138

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

2013-05-01

139

Do dune sands redden with age? The case of the northwestern Negev dunefield, Israel  

NASA Astrophysics Data System (ADS)

The redness index of aeolian sand has been shown to be a promising qualitative spectroscopic method to define sand grain redness intensity, which reflects the extent of iron-oxide quartz grain coatings. This study investigates the relationship between redness intensity and optically stimulated luminescence (OSL) based depositional ages of sand samples taken from exposed and fully-drilled vegetated linear dunes in the northwestern Negev dunefield, Israel. Sand redness intensity did not vary greatly along the Negev sand transport paths and dune sections dated to be active during the Late Pleistocene (˜18-11.5 ka), Late Holocene, and modern times. No correlation was found between RI intensity (i.e., redness) and the depositional age of the sand. The relatively uniform RI values and sedimentological properties along most of the dunes suggest that sand grain coating development, and consequent rubification, have probably been minimal since the Late Pleistocene. Although it is possible that RI developed rapidly following deposition in a wetter Late Pleistocene climate, the drier and less stormy Holocene does not seem conducive to sand-grain rubification. Based on analyses of northern Sinai sand samples, remote sensing, and previous studies, we suggest that the attributes of the sand grain RI have been inherited from upwind sources. We propose that the sand grain coatings are early diagenetic features that have been similarly red since their suggested aeolian departure from the middle and upper Nile Delta.

Roskin, Joel; Blumberg, Dan G.; Porat, Naomi; Tsoar, Haim; Rozenstein, Offer

2012-08-01

140

Sand rubification with time? The case of the Sinai - Negev erg  

NASA Astrophysics Data System (ADS)

The redness index (RI) (RI = R2/(B*G3) of aeolian sand has been shown to be a promising qualitative spectroscopic method to define sand grain redness intensity, which reflects the extent of iron-oxide quartz grain coatings(1,2). Using the RI, this study investigates the relationship between redness intensity and optically stimulated luminescence (OSL) based depositional ages of sand samples taken from exposed and fully-drilled vegetated linear dunes in the northwestern Negev dunefield, Israel at the downwind end of the Sinai Negev erg. Sand redness intensity did not vary greatly along the Negev sand transport paths and dune sections dated to be active during the Late Pleistocene, late Holocene, and modern times. No correlation was found between RI intensity (i.e., redness) and the depositional age of the sand. The relatively uniform RI values and sedimentological properties along most of the dunes suggest that sand grain coating development, and consequent rubification, have probably been minimal since the Late Pleistocene. Although it is possible that RI developed rapidly following deposition in a wetter Late Pleistocene climate, the drier and less stormy Holocene does not seem conducive to sand-grain rubification. Based on analyses of northern Sinai sand samples, remote sensing, and previous studies, we suggest that the attributes of the sand grain RI have been inherited from upwind sources. We propose that the sand grain coatings are early diagenetic features that have been similarly red since their suggested aeolian departure from the middle and upper Nile Delta.

Roskin, J.; Rozenstein, O.; Tsoar, H.; Blumberg, D. G.; Porat, N.

2012-04-01

141

Using AMS of weakly deformed red beds for determining the spatial and temporal evolution of layer parallel shortening fabrics in the Cordilleran of Wyoming, USA  

NASA Astrophysics Data System (ADS)

Integrated anisotropy of magnetic susceptibility (AMS) analysis, paleomagnetic, and structural studies are underway to better understand the 3-D kinematic evolution and mechanical processes that generated Cordilleran deformation in Wyoming. AMS sampling has been concentrated in the Triassic Chugwater Group from multiple basement-cored arches across the Laramide foreland of Wyoming and in the Triassic Ankareh Formation from multiple thrust sheets in the Wyoming salient of the Sevier orogneic belt. Magnetic susceptibility of these samples originates from ferromagnetic hematite and paramagnetic phyllosilicates. A general progression of AMS ellipsoids is developed as primary sedimentary fabrics are overprinted by weak tectonic fabrics. Primary sedimentary fabrics have distinctly oblate AMS ellipsoids with Kmin axes perpendicular to bedding. With increasing deformation, a composite fabric develops with triaxial AMS ellipsoids and Kmax axes (magnetic susceptibility lineations) sub-parallel to the intersection of weak layer-parallel shortening (LPS) fabrics (defined by rotated and recrystallized phyllosilicates and hematite) with bedding. Most sampled sites have well developed Kmax directions with 95% uncertainties < 10 degrees, which are typically sub-parallel to structural trend. AMS directions have been compared with minor fault kinematic, strain and cleavage/fracture data to test the viability of AMS as a proxy for LPS fabrics. Correlations, quantified using a refined weighted least squares method that incorporates both measurement and fabric uncertainties, indicate that AMS is a powerful tool in defining LPS directions in weakly deformed rocks. LPS directions in thrust sheets of the Sevier belt define an overall radial pattern and are interpreted to reflect stresses transmitted from the hinterland through the wedge and topographic stresses along the growing front of the wedge. LPS directions in the Laramide foreland are interpreted to partly reflect basal traction during flat slab subduction beneath cratonic lithosphere, along with spatial-temporal variations in stress related to basement anisotropy and evolving fault systems.

Yonkee, A.; Weil, A. B.

2010-12-01

142

The extraction of bitumen from western oil sands: Volume 2. Final report  

SciTech Connect

The program is composed of 20 projects, of which 17 are laboratory bench or laboratory pilot scale processes or computer process simulations that are performed in existing facilities on the University of Utah campus in north-east Salt Lake City. These tasks are: (1) coupled fluidized-bed bitumen recovery and coked sand combustion; (2) water-based recovery of bitumen; (3) oil sand pyrolysis in a continuous rotary kiln reactor; (4) oil sand pyrolysis in a large diameter fluidized bed reactor; (5) oil sand pyrolysis in a small diameter fluidized bed reactor; (6) combustion of spent sand in a transport reactor; (7) recovery and upgrading of oil sand bitumen using solvent extraction methods; (8) fixed-bed hydrotreating of Uinta Basin bitumens and bitumen-derived hydrocarbon liquids; (9) ebullieted bed hydrotreating of bitumen and bitumen derived liquids; (10) bitumen upgrading by hydropyrolysis; (11) evaluation of Utah`s major oil sand deposits for the production of asphalt, high-energy jet fuels and other specialty products; (12) characterization of the bitumens and reservoir rocks from the Uinta Basin oil sand deposits; (13) bitumen upgrading pilot plant recommendations; (14) liquid-solid separation and fine tailings thickening; (15) in-situ production of heavy oil from Uinta Basin oil sand deposits; (16) oil sand research and development group analytical facility; and (17) process economics. This volume contains reports on nine of these projects, references, and a bibliography. 351 refs., 192 figs., 65 tabs.

Oblad, A.G.; Dahlstrom, D.A.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1997-11-26

143

Sand Castle Saturation  

NSDL National Science Digital Library

In this activity about saturation (page 1 of PDF), learners will build a series of sand castle towers using a 16 oz cup. Learners begin with completely dry sand and then add a ¼ cup of water to the sand for each successive tower, each time measuring the height and width of the resulting sand mound until they make a tower that maintains the shape of the cup. Relates to the linked video, DragonflyTV: Sand Dunes.

Twin Cities Public Television, Inc.

2005-01-01

144

National Metal Casting Research Institute final report. Volume 1, Sand reclamation  

Microsoft Academic Search

A mobile thermal foundry sand reclamation unit was designed and constructed. This unit consisted of thermal and mechanical sand reclamation equipment installed on the bed of a 50 foot low-boy trailer. It was transported to a number of Midwest foundries for on-site demonstration of the sand reclamation process. This allowed participating foundries to have their own refuse sand (10-100 tons)

L. F. Vondra; J. S. Burningham

1995-01-01

145

Evolution of radiative sand ridge field of the South Yellow Sea and its sedimentary characteristics  

Microsoft Academic Search

A sand ridge field of 22 470 km2 consists of fine sands and silts originally from the old Changjiang River sediment during the late Pleistocene period. Late\\u000a Holocene sand stratum with its well-preserved larmnary bedding of more clay particles reflects the influence from the Yellow\\u000a River. There are three genetic types of morphology of sand ridge field as follows: (i)

Ying Wang; Dakui Zhu; Kunyuan You; Shaoming Pan; Xiaodong Zhu; Xinqing Zou; Yongzhan Zhang

1999-01-01

146

Gas fluidized sand, liquid or solid?  

NASA Astrophysics Data System (ADS)

If one can measure flow properties of a granular material which are very reminiscent of a simple liquid, it would instill confidence that a relatively simple granular fluid mechanical model may exist. A granular fluid very reminiscent of a simple liquid is gas fluidized sand. Such sand can be easily stirred regardless of depth beneath the surface. In order to test the fluid like behavior more rigorously we have performed a series of experiments on the drag force on a ball moving vertically through the sand. At low fluidization rates (non bubbling) we have found that a brass sphere will sink only to a certain depth at which point its weight is entirely supported by the sand. Deeper yet, the sphere again moves freely. When pressure is applied to the top of the bed, this solid like layer can be moved closer to the top surface of the bed. These measurements were performed at flow rates where light scattering studies have shown all the grains to be motionless. Our experiments suggest that gas fluidized sand shows more complexity than a solid with very a very low yield stress. We thank the NSF-REU program for partial support of this research.

Stoker, David S.; Rutgers, Maarten A.

2000-03-01

147

Experimental study of transverse bed motion in rotary kilns  

Microsoft Academic Search

Slumping and rolling beds have been studied extensively in a continuous pilot kiln and batch rotary cylinders. Solids investigated\\u000a include nickel oxide pellets, limestone, sand, and gravel. The effect of variables such as rotational speed, bed depth, cylinder\\u000a diameter, particle size, and particle shape on bed motion has been determined. For a given material, the different modes of\\u000a bed motion

H. Henein; J. K. Brimacombe; A. P. Watkinson

1983-01-01

148

Update on Regulation of Sand Transport in the Colorado River by Changes in the Surface Grain Size of Eddy Sandbars Over Multiyear Timescales.  

National Technical Information Service (NTIS)

In settings where the transport of sand is partially or fully supply limited, changes in the upstream supply of sand are coupled to changes in the grain size of sand on the bed. In this manner, the transport of sand under the supply-limited case is grain-...

D. J. Topping D. M. Rubin J. C. Schmidt

2008-01-01

149

Sedimentological, Mineralogical and Geochemical Characterization of Sand Dunes in Saudi Arabia  

NASA Astrophysics Data System (ADS)

Sedimentological, mineralogical, morphological and geochemical studies of sand dunes from ten locations in Saudi Arabia were conducted in order to determine the differences between them and to find out the provenance and tectonic setting of these sand dunes. Sixty seven samples were collected from different sand dunes types ranging in morphology from linear, barchans, parabolic to stars dunes. In overall, the sand dunes are fine to coarse grained mean grain size, moderately sorted, near symmetrical skewness with mesokurtic distribution characterized sand dunes in most locations. The sand dunes grains are subrounded in all locations except in the Red sea, Qassim, central Arabia and the eastern province which showed sub-angular grains. The main mineral compositions of studied aeolian sand dunes are quartz, feldspar, calcite, and mica. Quartz is the dominant mineral in locations with significant amount of feldspars and mica in Najran, Red sea and Central Arabia locations. Moreover, calcite is present in Sakaka and NW Empty Quarter (Jafurah). Basement related sand dunes in Najran, Central Arabia and Red sea locations are sub-mature in terms of their mineralogical maturity. Whereas, sand dunes in other locations are texturally mature except those from the Red sea which showed sub-mature sand. The sands are classified as quartz arenite, except in the basement related sand dunes in Najran, central Arabia and the Red sea are ranging from sub-arkose, sub-litharenite and lithraenite. Morphologically, parallel to sub-parallel sand ridges with NE-SW orientation occurred in east and north parts of Empty Quarter (Najran and Jafurah) and NW-SE orientation in Dahna and Nafud deserts in central and north regions of Saudi Arabia. Parabolic sand dunes characterized the Nafud desert (Hail, Sakaka, Tayma locations). Barchans and star sand dunes characterize the Empty Quarter (Jafurah). Major, trace, and rare earth elements studies were carried out to determine the composition, provenance and tectonic history of the sand dunes. Geochemical analysis indicated that most of sand dunes are quartz arenite type, except in the Red sea, basement related central Saudi Arabia and Najran areas, the sand dunes are sub-arkoses, sub-litharenite and litharenite. The concentration of major,trace and rare elements showed active continental margins as a tectonic setting of Red sea, basement related Najran and central Arabia sand dune. In contrast, passive continental margins for the other locations. The distribution of major, trace and rare earth elements showed similarity in chemical composition between basement related sand dunes in Red sea, Najran and central Arabia.

Benaafi, Mohammed; Abdullatif, Osman

2014-05-01

150

Evaluation of integrated anaerobic/aerobic fixed-bed sequencing batch biofilm reactor for decolorization and biodegradation of azo dye acid red 18: comparison of using two types of packing media.  

PubMed

Two integrated anaerobic/aerobic fixed-bed sequencing batch biofilm reactor (FB-SBBR) were operated to evaluate decolorization and biodegradation of azo dye Acid Red 18 (AR18). Volcanic pumice stones and a type of plastic media made of polyethylene were used as packing media in FB-SBBR1 and FB-SBBR2, respectively. Decolorization of AR18 in both reactors followed first-order kinetic with respect to dye concentration. More than 63.7% and 71.3% of anaerobically formed 1-naphthylamine-4-sulfonate (1N-4S), as one of the main sulfonated aromatic constituents of AR18 was removed during the aerobic reaction phase in FB-SBBR1 and FB-SBBR2, respectively. Based on statistical analysis, performance of FB-SBBR2 in terms of COD removal as well as biodegradation of 1N-4S was significantly higher than that of FB-SBBR1. Spherical and rod shaped bacteria were the dominant species of bacteria in the biofilm grown on the pumice stones surfaces, while, the biofilm grown on surfaces of the polyethylene media had a fluffy structure. PMID:23138064

Hosseini Koupaie, E; Alavi Moghaddam, M R; Hashemi, S H

2013-01-01

151

Analysis of Atmospheric Fluidized Bed Combustion Agglomerates. Final Report.  

National Technical Information Service (NTIS)

Chemical and textural studies of AFBC agglomerates have revealed detailed information regarding the mechanisms of agglomeration. The formation of agglomerates in a silica sand bed can be described by a four step process: initial ash coatings of quartz gra...

D. Perkins D. W. Brekke F. R. Karner

1984-01-01

152

China Dust and Sand  

... article title:  Dust and Sand Sweep Over Northeast China     View Larger Image ... these views of the dust and sand that swept over northeast China on March 10, 2004. Information on the height of the dust and an ...

2013-04-16

153

Sand Analysis Lab Activity  

NSDL National Science Digital Library

An inclass introductory level activity for science and nonscience majors that explores the properties of sand in order to identify depositional environments. Sand Analysis Lab (Microsoft Word 71kB May18 12)

Weiss, Tarin

154

Mineral Sands Down Under  

NSDL National Science Digital Library

This resource describes what mineral sands are, and discusses the heavy, dark-colored minerals that they contain (rutile, ilmenite, zircon, monazite). A map shows locations of mineral sands deposits in Australia.

155

The extraction of bitumen from western oil sands. Quarterly report, April--June 1993  

SciTech Connect

Accomplishments are briefly described for the following tasks: environmental impact statement; coupled fluidized bed bitumen recovery and coked sand combustion; water-based recovery of bitumen; rotary kiln process for recovery of bitumen and combustion of coke sand; recovery of bitumen from oil sands using fluidized bed reactors and combustion of spent sands in transport reactors; recovery of bitumen from oil sand and upgrading of bitumen by solvent extraction; catalytic and thermal upgrading of bitumens and bitumen-derived liquids; evaluation of Utah`s major oil sand deposits for the production of asphalt, high energy jet fuels and other specialty products; development of mathematical models for bitumen recovery and processing; completion of the cost examination study of the pilot plant restoration; development studies of equipment for three-product gravity separation of bitumen and sand; determine thickener requirements; and environmental studies of the North Salt Lake pilot plant rehabilitation and eventual operation and those environmental problems associated with eventual commercial products.

Oblad, A.G.; Bunger, J.W.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1993-07-01

156

A playa deposit of pre-Yellow Sands age (upper Rotliegend/Weissliegend) in the Permian of northeast England  

NASA Astrophysics Data System (ADS)

A complexly interbedded thin succession of sandstone, siltstone and mudstone beneath the Permian Yellow Sands Formation (upper Rotliegend/Weissliegend) was cored in a borehole 11 km off the coast of northeast England. The cored strata rest unconformably on fissured Westphalian B mudstone and mainly comprise low-dipping fine- to coarse-grained grey sandstone with unevenly spaced thinner dark-red to grey mudstone beds and laminae. Most of the sandstone beds are moderately to poorly sorted, fine- to very fine-grained subarkoses, with some sublitharenites, and are weakly to strongly cemented by dolomite (predominant), kaolinite and illite; sedimentary structures include subhorizontal plane to wavy lamination, ripple lamination, salt ridges and soft-sediment deformation. The siltstones and mudstones are more uniform in lithology and primary thickness; they contain sandstone-filled desiccation cracks, mudstone saucers and narrow sandstone dykes. Traces of possible former evaporite minerals are concentrated in the sandstones. By comparison with modem desert depositional environments, these strata are interpreted as the deposits of a playa occupying a depression on a stony, deflationary desert surface on a rock pediment or peneplain flanking the ancestral Pennines. The floor of the depression, which probably lay in the capillary fringe just above the contemporary water table, was periodically flooded so as to form a shallow playa lake. Comparable successions beneath the Yellow Sands have not been recorded from surface exposures in northeast England but mudstone beds at this stratigraphical level have been recorded in four other cored offshore boreholes and are presumed to be of similar origin to those described in this study. The stratigraphical position of these deposits suggests that they may be of pre-Yellow Sands age and coeval with or younger than the Basal Permian Breccia. Palynological analysis of mudstone samples from the core reveal the presence of plant material and indeterminate, pyrite-invested, possibly indigenous bisaccate pollen indicative of a vegetated hinterland with deposition occurring within a reducing, possibly sulphide-rich environment.

Turner, Brian R.; Smith, Denys B.

1997-12-01

157

Asbestos in play sand  

Microsoft Academic Search

A letter in the New England Journal of Medicine (Oct. 2 issue) stated that a carbonate sand marketed in New Jersey was contaminated with 2 to 4 percent tremolite asbestos. The authors were called on by one of the federal agencies to repeat the analysis of this sand, specifically for its asbestos content. The sand was pulverized and immersed in

A. M. Langer; R. P. Nolan

1987-01-01

158

Exploring Products: Nano Sand  

NSDL National Science Digital Library

In this activity, learners explore how water behaves differently when it comes in contact with "nano sand" and regular sand. Learners learn about the hydrophobic properties of "nano sand." Use this activity to talk about how many materials behave differently at the nanoscale.

Network, Nanoscale I.; Sciencenter

2010-01-01

159

Qualifying tight sands  

Microsoft Academic Search

Qualifying parts of Kentucky's Big Sand gas field for tight sands designation will not be the only benefit to come out of the work now being done by the Kentucky Oil and Gas Association's Tight Sands Committee. The committee plans to evaluate all oil and gas producing formations in E. Kentucky for possible designation. Committee members are gathering detailed information

Harbert

1981-01-01

160

Books of sand  

Microsoft Academic Search

Books of Sand are interactive installations that relate the movement of hands in the sand to hypertexts containing Jorge Luis Borges texts taken from the Web. It consists of one or more glass buckets full of sand that when touching it with the hands, projected codes retrieved from the Web arise interacting with the movement of the hands.A video camera

Sardón Mariano

2006-01-01

161

The performance of pumice as a filter bed material under rapid filtration conditions  

Microsoft Academic Search

Deep bed sand filters are used extensively in drinking water and wastewater treatment. In this study, sand and pumice were used as a filtration media under rapid filtration conditions and performance results for both were compared. Turbidity removal performance and head losses were investigated as functions of filtration rate, bed depth and particle size. Under the same experimental conditions such

Burhanettin Farizoglu; Alper Nuhoglu; Ergun Yildiz; Bulent Keskinler

2003-01-01

162

Paleoenvironment and depositional environment of Miocene Olcese Sand, Bakersfield, California  

SciTech Connect

The Olcese Sand near Bakersfield, California, contains evidence of a range of paleoenvironments including nonmarine, estuarine, and outer shelf depositional settings. Foraminifera from surface and subsurface samples place the Olcese in the Saucesian and Relizian of the California benthic stages. A pumice bed in the Olcese has been dated by fission track methods at 15.5 Ma. The Olcese Sand interfingers with the underlying Freeman Silt and the overlying Round Mountain Silt. In the type area, in Round Mountain oil field, the Olcese is 300-360 m thick. The Olcese is subdivided into three environmental facies. In the Knob Hill Quadrangle, the lower Olcese consists of (1) thinly bedded to blocky white tuffaceous silt and sand, or (2) planar cross-bedded fine to coarse-grained sand with pumice pebbles lining the bedding surfaces. Fossil mollusks and skate teeth indicate a shallow marine environment for the lower Olcese. Although the Olcese is predominantly a marine unit, the middle Olcese is nonmarine, with lenses of marine deposition. The middle Olcese is well exposed in the Knob Hill, Oil Center, and Rio Bravo Ranch Quadrangles, and is characterized by fine to coarse sand with occasional gravel lenses, strong cross-bedding, and a blue-gray color. The upper Olcese is a very fine to medium-grained, marine sand that fines upward into a sandy siltstone southward toward the Kern River. Foraminifera and mollusks from outcrops in the Rio Bravo Ranch Quadrangle indicate outer shelf to estuarine environments for the upper Olcese. The varying environments in the Olcese Sand reflect slight but frequent fluctuations in water depth and can be used to interpret the basin-margin history.

Olson, H.C.

1986-04-01

163

Red Tide  

NSDL National Science Digital Library

This CDC web page includes links to PDF or html formatted files containing information about Karenia brevis, a phytoplankton responsible for toxic red tide events. Links include information about red tide, what the CDC is doing about red tide, links to other red tide related sites, and publications about red tide.

Control, U. S.

164

A note on tidally generated sand waves  

NASA Astrophysics Data System (ADS)

The process leading to the formation of sand waves in tide dominated coastal areas is investigated by means of the linear stability analysis of a flat sandy bottom subject to oscillatory tidal currents. The conditions for the decay or amplification of small bottom perturbations are determined for arbitrary values of the parameters of the problem. According to field observations, the initial growth of sand waves requires a minimum amplitude of the tidal current, even when the critical bed shear stress for the initial motion of sediment is set equal to zero. Moreover the minimum amplitude depends on sediment characteristics. In particular, the analysis shows that sand waves appear only for a sandy bottom and their growth does not take place when a coarse sediment covers the sea bed. The solution procedure extends the truncation method which is often used to describe the flow generated by the interaction of bottom perturbations with the oscillatory tidal current. The obtained results show that the truncation method describes the mechanism inducing the growth of sand waves, but values of the parameters exist for which its results are not quantitatively accurate. Finally, the asymptotic approach for large values of both r, which is the ratio between the amplitude of the horizontal tidal excursion and the wavelength of the bottom perturbations, and of the stress parameter s is modified in the bottom boundary layer to describe cases characterized by values of s of order one, which is the order of magnitude suggested by an analysis of field data.

Besio, G.; Blondeaux, P.; Frisina, P.

2003-06-01

165

Seismic investigations in South West African river beds  

Microsoft Academic Search

Summary In sand-filled river channels in arid parts of South West Africa it is of importance to find methods of locating the rock surface under the sand, for purposes of water supply. This paper describes preliminary investigations in three such river beds, to test the applicability to this problem of the seismic refraction method, using the hammer-electronic seismic instrument previously

D. I. Gough; C. B. van Niekerk

1957-01-01

166

Measurement of bed load in rivers  

Microsoft Academic Search

The Helley-Smith bed load sampler is a direct measuring, pressure differential sampler designed for use with sediment ranging in size from coarse sand to medium gravel. For sediment particle sizes between 0.50 and 16 mm, the Helley-Smith bed load sampler has a near- perfect sediment trapping efficiency. For particle sizes smaller than 0.50 mm or larger than about 16 mm,

WILLIAM W. EMMETT

1981-01-01

167

Application of mineral bed materials during fast pyrolysis of rice husk to improve water-soluble organics production.  

PubMed

Fast pyrolysis of rice husk was performed in a spout-fluid bed to produce water-soluble organics. The effects of mineral bed materials (red brick, calcite, limestone, and dolomite) on yield and quality of organics were evaluated with the help of principal component analysis (PCA). Compared to quartz sand, red brick, limestone, and dolomite increased the yield of the water-soluble organics by 6-55% and the heating value by 16-19%. The relative content of acetic acid was reduced by 23-43% with calcite, limestone and dolomite when compared with quartz sand. The results from PCA showed all minerals enhanced the ring-opening reactions of cellulose into furans and carbonyl compounds rather than into monomeric sugars. Moreover, calcite, limestone, and dolomite displayed the ability to catalyze the degradation of heavy compounds and the demethoxylation reaction of guaiacols into phenols. Minerals, especially limestone and dolomite, were beneficial to the production of water-soluble organics. PMID:22750499

Li, R; Zhong, Z P; Jin, B S; Zheng, A J

2012-09-01

168

Eye redness  

MedlinePLUS

Bloodshot eyes; Red eyes; Scleral infection; Conjunctival infection ... There are many possible causes of a red eye or eyes. Some are cause for concern; some are medical emergencies. Others are nothing to worry about. How red the eye appears ...

169

Red clover  

MedlinePLUS

Red clover is a plant. The flower tops are used to make medicine. Red clover is used for many conditions, but so ... lowering cholesterol or controlling hot flashes in women. Red clover is used for cancer prevention, indigestion, high ...

170

Observations of Sand Transport Processes Over Sorted Bedforms  

NASA Astrophysics Data System (ADS)

High resolution sonar surveys in the past decade have revealed that complex sorted bedforms (rippled scour depressions, RSDs) are ubiquitous features on many sandy inner shelves. These features consist of alternating bands of coarse and fine sand with along-shore scales of 10 to 1000 m and across-shore scales of 100 to 5000 m. Modeling approaches for these features have ranged from rules-based approaches to sediment transport physics based approaches. However, the sediment transport processes over fine and coarse sand with combined weakly non-linear waves and mean current forcing are poorly understood. Specifically, the relative roles of bedload and suspended load forced by non-linear waves and mean currents over large ripples in coarse sand and smaller ripples, or low-relief bed conditions in fine sand are not well understood. For instance, tripod mounted rotary sonar observations have generally shown onshore ripple migration forced by non-linear wave velocities to be the dominant transport process in coarse sand. However, larger-scale sonar and grab sample surveys have shown along-shore grain size variability that is presumably forced by along-shore mean currents. Over the past three years, observations were conducted at the Martha's Vineyard Coastal Observatory RSD field in attempts to quantify the relative roles of these processes. A quadpod, with a rotary sidescan sonar and a 2-axis pencil beam sonar to measure ripple morphology, was deployed in both coarse and fine sand in successive winter seasons. The quadpod also had a 3-axis bistatic pulse coherent acoustic Doppler profiling system that is capable of measuring near-bed (within 30 cm of the seafloor) suspended and bedload transport. Bedload was estimated using spectral processing on the bed and bedload backscatter, thus the high intensity returns from the stationary bed could be separated from returns from the moving bedload in the frequency domain. Preliminary analysis of the observations revealed that in fine sand the transport is dominated by suspended load forced by wave-resuspension and mean current transport. The observations in fine sand contained many storms of varying energy thus are fairly robust. The observations in coarse sand only had 4 hours of data during moderate-energy active conditions, due to a equipment failure, thus additional data and analysis is required to determine the amount of along-shore transport and the relevant forcing processes in coarse sand during more energetic events. From the available data in coarse sand, onshore bedload and near-bed suspended load transport (within 1 cm of the seafloor) forced by non-linear waves dominated the flux, consistent with prior observations of bedload flux estimated from ripple migration.

Traykovski, P.

2005-05-01

171

Advances in liquid fluidized-bed heat exchanger development  

Microsoft Academic Search

The paper reports the first heat transfer results from a horizontal liquid fluidized-bed heat exchanger. Geothermal water from Raft River Geothermal Wells provided the heat source. Treated water was the secondary fluid. Silica sand closely screened to 16 mesh was the bed material. The exchanger was 8 in. in diameter by 15 in. long. Heat transfer results are compared with

E. S. Grimmett; A. F. Fanous; C. A. Allen

1977-01-01

172

Cone penetration testing for evaluating the liquefaction potential of sands. Master's thesis  

SciTech Connect

Before the Niigata and Alaskan earthquakes of 1964, most geotechnical engineers had expressed little concern about the dynamic behavior of saturated sand layers. Regardless of their density, sands were generally considered quite incompressible and stable for foundation and construction uses. The only disadvantages for the universal use of sands considered were the consequences of their high permeabilities. Damage to many structures founded on saturated sand beds and other physical signs of loss of strength in sand layers during the two 1964 earthquakes resulted in the formation of a new area of geotechnical engineering. A new term, 'liquefaction,' was coined to describe the more visible outcomes of earthquake-related failures.

Carter, R.R.

1988-05-01

173

An electrification mechanism of sand grains based on the diffuse double layer and Hertz contact theory  

NASA Astrophysics Data System (ADS)

The electrification of sand grains lifting off from sand bed is investigated experimentally. It was found that sand grains were able to carry charges, which is comparable in magnitude with the experimental results and is related to grain sizes, pH of soil, relative humidity, and electric field. Based on the theory of diffuse double layer (DDL) and Hertz contact theory, an electrification mechanism due to the break of DDLs of sand grains is presented and a formula which takes environmental conditions and grain parameters into consideration is obtained to calculate the charge-mass ratio of lift-off sand grains.

Xie, Li; Han, Kui; Ma, Yanping; Zhou, Jùn

2013-09-01

174

A study on the stability of laminar open-channel flow over a sandy rippled bed  

Microsoft Academic Search

The bed of a river often features some kinds of bedform, such as sand ripples, dunes, and so on. Even if the bed is smooth\\u000a initially, disturbances arising from the bed or other external sources will cause the laminar flow in an open channel to become\\u000a unstable as soon as the flow develops, thereby leading to the formation of sand

Yuchuan Bai; Haijue Xu

2005-01-01

175

Aeolian Sand Transport with Collisional Suspension  

NASA Technical Reports Server (NTRS)

Aeolian transport is an important mechanism for the transport of sand on Earth and on Mars. Dust and sand storms are common occurrences on Mars and windblown sand is responsible for many of the observed surface features, such as dune fields. A better understanding of Aeolian transport could also lead to improvements in pneumatic conveying of materials to be mined for life support on the surface of the Moon and Mars. The usual view of aeolian sand transport is that for mild winds, saltation is the dominant mechanism, with particles in the bed being dislodged by the impact of other saltating particles, but without in-flight collisions. As the wind becomes stronger, turbulent suspension keeps the particles in the air, allowing much longer trajectories, with the corresponding increase in transport rate. We show here that an important regime exists between these two extremes: for strong winds, but before turbulent suspension becomes dominant, there is a regime in which in-flight collisions dominate over turbulence as a suspension mechanism, yielding transport rates much higher than those for saltation. The theory presented is based on granular kinetic theory, and includes both turbulent suspension and particle-particle collisions. The wind strengths for which the calculated transport rates are relevant are beyond the published strengths of current wind tunnel experiments, so these theoretical results are an invitation to do experiments in the strong-wind regime. In order to make a connection between the regime of saltation and the regime of collisional suspension, it is necessary to better understand the interaction between the bed and the particles that collide with it. This interaction depends on the agitation of the particles of the bed. In mild winds, collisions with the bed are relatively infrequent and the local disturbance associated with a collision can relax before the next nearby collision. However, as the wind speed increases, collision become more frequent and the agitation need not decay completely. In the regime of collisional suspension, the particles near the surface of the bed are assumed to be in a state of constant agitation. We indicate the conditions at the bed corresponding to the limits of saltation and collisional suspension and outline experiments, simulations, and modeling that have been undertaken to bridge these limits.

Jenkins, James T.; Pasini, Jose Miguel; Valance, Alexandre

2004-01-01

176

Have the northwest Negev dunefield sands reddened since their deposition?  

NASA Astrophysics Data System (ADS)

Sand grain coating redness has been extensively both in coastal and inland desert dunes. In Israel, sand redness has been quantified by calculating a spectral redness index (RI) using single RGB bands (RI= R2/(B*G3)) from reflectance spectroscopy. The RI values have been correlated to ferric oxide mass that was dissolved from sand grain coatings (Ben Dor et al., 2006; Tsoar et al., 2008). Five main requirements have been proposed to enhance sand grain reddening: iron source from the weathering of iron-bearing minerals originating from parent rock or aeolian dust, minimum moisture content, oxidizing interstitial conditions, sediment stability and time. Thus, as many researches have suggested, when the source factors and climatic conditions are homogenous, redder sands indicate increased maturity. The northwest Negev dunefield has been classified by Tsoar et al. (2008) into 3 incursion units based upon contouring a grid of RI values for surface sand samples. The central incursion unit has been suggested to be younger due to relatively lower RI values that decrease to the east. This work tests the relationship between RI values and optically stimulated luminescence (OSL) ages of aeolian sand sampled from the near surface down to dune substrate throughout the NW Negev dunefield. Room-dried sand samples were measured in the laboratory with an ASD FieldSpec spectrometer and RI was calculated. Dune sections have been found to usually have similar RI values throughout their vertical profile despite OSL ages ranging between recent and Late Pleistocene. Along a W-E transect, RI values also tend to be similar. The central (Haluzza) part of the dunefield exhibits significantly lower RI values than RI of sands south of the Qeren Ridge. Dune base OSL ages possibly representing burial/stabilization of an initial incursion are slightly more mature in the south and may be evidence of the earliest dune incursion into the Negev. Thus the increased redness may be attributed to an older sand source but not to reddening in situ with time. Remotely sensed RI calculated from Landsat TM 5 (30 m pixel) RGB bands of bare Sinai sands also portrays the spatial RI difference between the central and southern sands. To summarize, we find no direct connection between dune sand deposition age and sand grain coating redness in the Negev dunes. It seems that stable aeolian sand and dune sections in the Negev have not reddened since their deposition. Sand grain coating redness was probably inherited during an earlier diagenetic stage in an environment different than today's. References Ben-Dor, E., Levin, N., Singer, A., Karnieli, A., Braun, O. & Kidron, G.J., 2006. Quantitative mapping of the soil rubification process on sand dunes using an airborne hyperspectral sensor. Geoderma, 131:1-21. Tsoar, H., Wenkart, R. & Blumberg, D.G., 2008. Formation and geomorphology of the north-western Negev sand dunes. In (Breckle, S.W., Yair, A.& Veste, M.) eds., Arid dunes ecosystems: The Nizzana sands in the Negev Desert. Springer pub. 475 pp.

Roskin, Joel; Tsoar, Haim; Blumberg, Dan G.; Porat, Naomi; Rozensten, Ofer

2010-05-01

177

Kentucky tar sand project  

Microsoft Academic Search

Engineering details and pilot-plant results from a pioneering investigation based on a Kentucky tar-sand reserve are presented. The tar sand deposits of Kentucky are generally situated in the southeastern rim of the Illinois Basin along the southern boundary of the Western Coal Field region. In a recent study of US tar sand reserves, it was reported that over 3.4 billion

M. N. Kelley; H. D. II Jones; F. W. Lewis

1985-01-01

178

Sand Sea Wonders: Geology  

NSDL National Science Digital Library

This site describes the geology of The Great Sand Dunes National Monument and Preserve. Active links allow students to explore the geologic timeline, geologic cross section in animation, and the wind regime. A reversing dune is shown in animation and other dunes such as star, parabolic, barchan, and transverse are discussed. Another section illustrates sand recycling by seasonal streams. A sand deposits map shows topography, dunes watershed, old national monument boundary, roads, and surface water and a section called 'How Much Sand' quantifies the description. Artwork on this site includes both adult and 'Hands on the Land' student artwork while photography depicts dunes, landscape, animals, plants, and human history.

179

Quasi-hydrodynamic lubrication effect of clay particles on sand grain erosion  

NASA Astrophysics Data System (ADS)

Minor changes in the mass physical properties of submerged sand beds can have significant consequences relative to bed stability against erosion. To examine the effect of small amounts of clay-sized particles in bed pore water on the critical shear stress ?c for the erosion of sand grains, flume experiments were carried out on the erosion of quartz sand beds impregnated with clay particles. Starting with no clay, as the clay mass fraction ? was increased, ?c was found to decrease below the value for pure sand ?co at ? = ?m, then reverted to ?co at ? = ?r and continued to increase above ?co as ? was increased further. Post-experimental analysis suggests that ?r is the pore space-filling fine sediment fraction above which sand erosion is significantly influenced by clay. In the range of ? ? ?m, slider-bearing type lubrication due to the viscosity of the clay-laden interstitial fluid appears to govern the dependence of ?c on ?, mimicking Petroff's law of thick-film lubrication. When ? < ?m, as ? decreases lubrication is increasingly curtailed by grain asperities, and ?c reverts ultimately to ?co at ? = 0. An equation relating ?c to ? is proposed in analogy with the quasi-hydrodynamic Stribeck function for lubrication. The observed effect of clay particles appears to be significant enough to require its consideration in coastal and estuarine sediment transport modeling. It may also be a factor in the estimation of bed stability when biological activity in the benthic boundary layer introduces fine particles in clean sand beds.

Barry, K. M.; Thieke, R. J.; Mehta, A. J.

2006-03-01

180

"Sand Boil" on Bay Bridge  

USGS Multimedia Gallery

"Sand boil" or sand volcano measuring 2 m (6.6 ft) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction). Vented sand contains-marine shell f...

2009-01-26

181

Evaluation of waste pyrolysis characteristics in a pressurized fluidized bed reactor  

Microsoft Academic Search

To obtain the distribution of fuel components to gas, tar and char in a pressurized fluidized bed waste pyrolyzer, experiments were conducted with a laboratory scale fluidized bed reactor. Waste samples were fed batchwise from the top of the reactor into the fluidized bed of silica sand and pyrolyzed by nitrogen\\/nitrogen–O2 gas and the effects of pressure, particle size, heating

Ayumi Ono; Mitsuaki Kurita; Taro Nagashima; Masayuki Horio

2001-01-01

182

Submarine sand sampler  

Microsoft Academic Search

A subsurface sampler which obtains samples of sand from offshore deposits is described. A 27-foot tube within a tube is lowered to the ocean floor while suspended from flotation tanks. The sampler is free of suspension cables and thus is detached from boat motions. Surface sand is sucked up through the suction tube and pumped to a container on deck

Casciano

1980-01-01

183

Oil from tar sands  

Microsoft Academic Search

For many years, the tar sand deposits of the world have drawn a great deal of attention as possible sources of enormous quantities of crude oil. The total in-place reserves are estimated at over 900 billion bbl, 3 times the liquid petroleum reserves of the world. In the Western Hemisphere, the largest deposits of tar sands occur in Canada, Venezuela,

Farouq Ali

1968-01-01

184

Sand Bank Weakly Nonlinear Stability Analysis  

NASA Astrophysics Data System (ADS)

In the continental shelf, tidal currents often give rise to large scale periodic bed forms named sand banks. Sand banks are long ridges (length of the order of several tens of kilometers) with a spacing (crest to crest distance) up to 10 km and a height up to several tens of meters. Their crests are almost aligned with the tidal currents, forming small positive or negative angles. Although reliable models based on linear stability analyses exist to predict the main geometrical characteristics of the sand banks as they start to appear, little is known on the morphodynamic processes that shape and maintain these bed forms in equilibrium conditions. A weakly nonlinear analysis is a powerful tool to investigate the equilibrium configuration attained by unstable bottom perturbations when the parameters of the problem are close to the critical values. However difficulties arise to apply a weakly nonlinear analysis of sand bank dynamics because the linear approaches predict infinite wavelengths of the most unstable mode close to the critical conditions. Here we first revisit the linear approach of Hulscher et al. (1993, Cont. Shelf Res. 13). In particular the time development of small amplitude bottom perturbations forced by tidal currents is studied using a different parameterization of both the bed shear stress and the sediment transport predictor which provides vanishing values of the sediment transport rate when the bottom shear stress is smaller than a critical value and accounts for the deviation of the sediment transport rate from the depth averaged velocity. With these improvements, both clockwise and counterclockwise sand banks are predicted. Moreover the wavelength of the most unstable mode close to the critical conditions turns out to be finite. This result opens the possibility to carry out a weakly nonlinear stability analysis. Then the time development of the most unstable mode is studied for values of the parameters close to the marginal conditions. The analysis provides estimates of the sand bank equilibrium amplitude and predicts equilibrium profiles characterized by crests sharper than the troughs, a feature often observed in field surveys.

Tambroni, N.; Blondeaux, P.

2006-12-01

185

LONG TERM RECHARGE OF TRICKLING FILTER EFFLUENT INTO SAND  

EPA Science Inventory

The rapid infiltration of trickling filter effluent onto natural delta sand beds at the Lake George Village Sewage Treatment Plant has been shown to produce the equivalent of tertiary treatment to the domestic wastewater since 1939 with no indication of exhaustion of the purifica...

186

Provenance and recycling of Arabian desert sand  

NASA Astrophysics Data System (ADS)

This study seeks to determine the ultimate origin of aeolian sand in Arabian deserts by high-resolution petrographic and heavy-mineral techniques combined with zircon U-Pb geochronology. Point-counting is used here as the sole method by which unbiased volume percentages of heavy minerals can be obtained. A comprehensive analysis of river and wadi sands from the Red Sea to the Bitlis-Zagros orogen allowed us to characterize all potential sediment sources, and thus to quantitatively constrain provenance of Arabian dune fields. Two main types of aeolian sand can be distinguished. Quartzose sands with very poor heavy-mineral suites including zircon occupy most of the region comprising the Great Nafud and Rub' al-Khali Sand Seas, and are largely recycled from thick Lower Palaeozoic quartzarenites with very minor first-cycle contributions from Precambrian basement, Mesozoic carbonate rocks, or Neogene basalts. Instead, carbonaticlastic sands with richer lithic and heavy-mineral populations characterize coastal dunes bordering the Arabian Gulf from the Jafurah Sand Sea of Saudi Arabia to the United Arab Emirates. The similarity with detritus carried by the axial Tigris-Euphrates system and by transverse rivers draining carbonate rocks of the Zagros indicates that Arabian coastal dunes largely consist of far-travelled sand, deposited on the exposed floor of the Gulf during Pleistocene lowstands and blown inland by dominant Shamal northerly winds. A dataset of detrital zircon U-Pb ages measured on twelve dune samples and two Lower Palaeozoic sandstones yielded fourteen identical age spectra. The age distributions all show a major Neoproterozoic peak corresponding to the Pan-African magmatic and tectonic events by which the Arabian Shield was assembled, with minor late Palaeoproterozoic and Neoarchean peaks. A similar U-Pb signature characterizes also Jafurah dune sands, suggesting that zircons are dominantly derived from interior Arabia, possibly deflated from the Wadi al-Batin fossil alluvial fan or even from Mesozoic sandstones of the Arabian margin accreted to the Cenozoic Zagros orogen. Due to extensive recycling and the fact that zircon is so resistant to weathering and erosion, the U-Pb age signatures are much less powerful a tracer of sedimentary provenance than framework petrography and heavy minerals. Actualistic provenance studies of dune fields at subcontinental scale shed light on the generation and homogenization of aeolian sand, and allow us to trace complex pathways of multistep sediment transport, thus providing crucial independent information for accurate palaeogeographic and palaeoclimatic reconstructions.

Garzanti, Eduardo; Vermeesch, Pieter; Andò, Sergio; Vezzoli, Giovanni; Valagussa, Manuel; Allen, Kate; Kadi, Khalid A.; Al-Juboury, Ali I. A.

2013-05-01

187

Provenance and recycling of Arabian desert sand  

NASA Astrophysics Data System (ADS)

This study seeks to determine the ultimate origin of aeolian sand in Arabian deserts by high-resolution petrographic and heavy-mineral techniques combined with zircon U-Pb geochronology. Point-counting is used here as the sole method by which unbiased volume percentages of heavy minerals can be obtained. A comprehensive analysis of river and wadi sands from the Red Sea to the Bitlis-Zagros orogen allowed us to characterize all potential sediment sources, and thus to quantitatively constrain provenance of Arabian dune fields. Two main types of aeolian sand can be distinguished. Quartzose sands with very poor heavy-mineral suites including zircon occupy most of the region comprising the Great Nafud and Rub' al-Khali Sand Seas, and are largely recycled from thick Lower Palaeozoic quartzarenites with very minor first-cycle contributions from Precambrian basement, Mesozoic carbonate rocks, or Neogene basalts. Instead, carbonaticlastic sands with richer lithic and heavy-mineral populations characterize coastal dunes bordering the Arabian Gulf from the Jafurah Sand Sea of Saudi Arabia to the United Arab Emirates. The similarity with detritus carried by the axial Tigris-Euphrates system and by transverse rivers draining carbonate rocks of the Zagros indicates that Arabian coastal dunes largely consist of far-travelled sand, deposited on the exposed floor of the Gulf during Pleistocene lowstands and blown inland by dominant Shamal northerly winds. A dataset of detrital zircon U-Pb ages measured on twelve dune samples and two Lower Palaeozoic sandstones yielded fourteen identical age spectra. The age distributions all show a major Neoproterozoic peak corresponding to the Pan-African magmatic and tectonic events by which the Arabian Shield was assembled, with minor late Palaeoproterozoic and Neoarchean peaks. A similar U-Pb signature characterizes also Jafurah dune sands, suggesting that zircons are dominantly derived from interior Arabia, possibly deflated from the Wadi al-Batin fossil alluvial fan or even from Mesozoic sandstones of the Arabian margin accreted to the Cenozoic Zagros orogen. Due to extensive recycling and the fact that zircon is so resistant to weathering and erosion, the U-Pb age signatures are much less powerful a tracer of sedimentary provenance than framework petrography and heavy minerals. Actualistic provenance studies of dune fields at subcontinental scale shed light on the generation and homogenization of aeolian sand, and allow us to trace complex pathways of multistep sediment transport, thus providing crucial independent information for accurate palaeogeographic and palaeoclimatic reconstructions.

Garzanti, Eduardo; Vermeesch, Pieter; Andò, Sergio; Vezzoli, Giovanni; Valagussa, Manuel; Allen, Kate; Kadi, Khalid; Al-Juboury, Ali

2013-04-01

188

Bonded-Sand/Loose-Sand Composite Mold.  

National Technical Information Service (NTIS)

The invention discusses a method of casting metal using evaporative pattern casting process patterns in combination with a bonded-sand form. The invention includes a dual-phase molding system that provides backup rigidity and physically restrains an EPC p...

J. S. Hansen P. C. Turner L. G. Higgins

1992-01-01

189

Dune-associated sand fluxes at the nearshore termination of a banner sand bank (Helwick Sands, Bristol Channel)  

NASA Astrophysics Data System (ADS)

Sand dunes typically migrate in opposing directions along the two sides of sand banks, reflecting a circulation driven by tidal current asymmetry, but it has been less clear how this pattern is distorted where banks intersect the coastline. The nearshore end of Helwick Sands, a banner bank in the Bristol Channel, was surveyed three times over three years, twice with a high-resolution multibeam echo-sounder. In both multibeam surveys, an unusual geometry was found over the crest of the bank, whereby dunes connect continuously with the dunes on the flanks, despite the flank dunes migrating in opposite directions. The crestal dunes thus appear to realign rapidly. We suggest that this morphological behaviour arises here because of vigorous wave-driven transport and because surface waves propagate almost exactly parallel to the crestal dunes. Sand transported parallel to the crestal dunes ensures that efficient reconnection occurs with dunes migrating along the flanks, particularly at low tide when wave currents are more strongly felt at the bed.

Schmitt, Thierry; Mitchell, Neil C.

2014-03-01

190

Birthmarks - red  

MedlinePLUS

Red birthmarks are skin markings created by blood vessels close to the surface of the skin. They ... There are two main categories of birthmarks. Red birthmarks are made ... vascular birthmarks. Pigmented birthmarks are areas in which ...

191

The fluctuation property of blown sand particles and the wind-sand flow evolution studied by numerical method.  

PubMed

Sand particles blown by wind cause serious environmental problems and many researchers are trying to understand the dynamic properties of blown sand better. But the existing numerical approaches have not been able to simulate many important characteristics of wind-sand flow. In this paper, the evolution and fluctuation properties of blown sand at a dynamic steady state are investigated by using a more effective method. Using the LES (large eddy simulation) method for air phase movement and the DEM (discrete element method) for solid phase movement along with the existing particle-bed splashing function, we have characterized the whole movement property of the wind-sand system. The results indicate that the saturation time decreases with the inlet friction velocity, and it gradually reaches the shortest saturation time of about 1s; the saturation length, which is about 14 m at the usual wind velocity, first increases with wind velocity and then reaches a plateau; within the saturation length, the sand transport rate at different positions varies with time; the sand transport rate of the stable wind-sand flow is non-uniform with distance downwind and time, and has a notable correlation with the inflow friction velocity. PMID:21626346

Ma, G S; Zheng, X J

2011-05-01

192

Sand Ripples and Dunes  

NASA Astrophysics Data System (ADS)

An erodible bed sheared by a fluid flow, gas or liquid, is generally unstable, and bed forms grow. This review discusses the following issues, in light of the recent literature: What are the relevant dynamical mechanisms controlling the emergence of bed forms? Do they form by linear instability or nonlinear processes such as pattern coarsening? What determines their timescales and length scales, so different in air and water? What are the similarities and differences between aeolian and subaqueous patterns? What is the influence of the mode of transport: bed load, saltation, or suspension? Can bed forms emerge under any hydrodynamical regime, laminar and turbulent? Guided by these questions, we propose a unified description of bed-form growth and saturation, emphasizing the hydrodynamical regime in the inner layer and the relaxation phenomena associated with particle transport.

Charru, François; Andreotti, Bruno; Claudin, Philippe

2013-01-01

193

Basaltic island sand provenance  

SciTech Connect

The Hawaiian Islands are an ideal location to study basaltic sand provenance in that they are a series of progressively older basaltic shield volcanoes with arid to humid microclimates. Sixty-two sand samples were collected from beaches on the islands of Hawaii, Maui, Oahu and Kauai and petrographically analyzed. The major sand components are calcareous bioclasts, volcanic lithic fragments, and monomineralic grains of dense minerals and plagioclase. Proportions of these components vary from island to island, with bioclastic end members being more prevalent on older islands exhibiting well-developed fringing reef systems and volcanic end members more prevalent on younger, volcanically active islands. Climatic variations across the island of Hawaii are reflected in the percentage of weathered detritus, which is greater on the wetter, northern side of the island. The groundmass of glassy, basaltic lithics is predominantly black tachylite, with lesser brown sideromelane; microlitic and lathwork textures are more common than holohyaline vitric textures. Other common basaltic volcanic lithic fragments are holocrystalline aggregates of silt-sized pyroxene or olivine, opaque minerals and plagioclase. Sands derived from alkalic lavas are texturally and compositionally indistinguishable from sands derived from tholeiitic lavas. Although Hawaiian basaltic sands overlap in composition with magmatic arc-derived sands in terms of their relative QFL, QmPK and LmLvLs percentages, they are dissimilar in that they lack felsic components and are more enriched in lathwork volcanic lithic fragments, holocrystalline volcanic lithic fragments, and dense minerals.

Marsaglia, K.M. (Univ. of Texas, El Paso, TX (United States). Dept. of Geological Sciences)

1992-01-01

194

Red Sea  

article title:  The Red Sea     View Larger Image ... Multi-angle Imaging SpectroRadiometer (MISR) image of the Red Sea was acquired on August 13, 2000. Located between the East African coast and the Saudi Arabian peninsula, the Red Sea got its name because the blooms of a type of algae,  Trichodesmium ...

2013-04-16

195

The Permian Weissliegend of NW Europe: The partial deformation of aeolian dune sands caused by the Zechstein transgression  

NASA Astrophysics Data System (ADS)

The Weissliegend is a European sandstone unit of largely late Early Permian age. It is underlain by the Early Permian Rotliegend red desert sandstones and is overlain by the conventionally accepted basal bed of the Zechstein-the bituminous marine shales of the Kupferschiefer. The Weissliegend sandstones are characteristically white or grey in colour and have been recognised beneath the North Sea, in Germany and in Poland. Equivalents, which are red or yellow in colour, occur in NE England and at the southern edge of the Moray Firth Basin in Scotland. From an examination of cliff and quarry exposures in Britain, and of drill cores from southern North Sea gas wells, it is now believed that the bulk of the Weissliegend sandstones (and their equivalents) were originally deposited as aeolian dunes. These dune sands, however, were later modified by a widespread event, the Zechstein transgression, which caused their partial homogenisation, the creation of large-scale soft-sediment deformation structures, and the local and minor reworking of some of the dune flanks. The preferred mechanism of deformation is interpreted as: (1) entrapment of large pockets of air within the bodies of the dunes by flanking and overlying wetted dune sands; (2) venting of the air pockets when the rising internal air pressures overcame the weight of the hydrostatic head of water and the capillary (cohesive) strength of the overlying wetted sands; (3) the rapid replacement of air by water, which caused liquidisation of the original dune laminae; and (4) the associated collapse and final consolidation of the sands into a tigher packing configuration. Deformations seem to be more developed in former transverse dunes than in seif dunes. The reason may be that the relatively tightly packed low-angle accretion bedding common on the flanks of seif dunes is more resistant to deformation than the looser avalanche sands that form a major part of transverse dunes. Limited reworking of former dune sands was probably best developed on the steep lee slopes of transverse dunes and the steeper upper slopes of seif dunes. The lack of reddening of the Weissliegend sandstones-proper is attributed to a combination of their accumulation above the Rotliegend water table, to the rapidity of the Zechstein transgression, and to the anoxic state of the early Zechstein sea floor. The Weissliegend sands, unlike the underlying Rotliegend into which they grade, were thus never in a diagenetic environment that was conducive to reddening. Finally, it is recommended that the term Weissliegend be dropped in any formational sense. It should only be retained for the Weissliegend proper, and their equivalents, to denote a complex facies association dominated by (1) the uppermost Early Permian Rotliegend dune sands (now partly deformed) that lay above the water table just prior to the Zechstein transgression, together with (2) the minor erosional marine products caused by that transgression. The latter, sensu stricto, are Zechstein sandstones of earliest Late Permian age.

Glennie, K. W.; Buller, A. T.

1983-05-01

196

Field assessment of alternative bed-load transport estimators  

USGS Publications Warehouse

Measurement of near-bed sediment velocities with acoustic Doppler current profilers (ADCPs) is an emerging approach for quantifying bed-load sediment fluxes in rivers. Previous investigations of the technique have relied on conventional physical bed-load sampling to provide reference transport information with which to validate the ADCP measurements. However, physical samples are subject to substantial errors, especially under field conditions in which surrogate methods are most needed. Comparisons between ADCP bed velocity measurements with bed-load transport rates estimated from bed-form migration rates in the lower Missouri River show a strong correlation between the two surrogate measures over a wide range of mild to moderately intense sediment transporting conditions. The correlation between the ADCP measurements and physical bed-load samples is comparatively poor, suggesting that physical bed-load sampling is ineffective for ground-truthing alternative techniques in large sand-bed rivers. Bed velocities measured in this study became more variable with increasing bed-form wavelength at higher shear stresses. Under these conditions, bed-form dimensions greatly exceed the region of the bed ensonified by the ADCP, and the magnitude of the acoustic measurements depends on instrument location with respect to bed-form crests and troughs. Alternative algorithms for estimating bed-load transport from paired longitudinal profiles of bed topography were evaluated. An algorithm based on the routing of local erosion and deposition volumes that eliminates the need to identify individual bed forms was found to give results similar to those of more conventional dune-tracking methods. This method is particularly useful in cases where complex bed-form morphology makes delineation of individual bed forms difficult. ?? 2007 ASCE.

Gaeuman, G.; Jacobson, R. B.

2007-01-01

197

Study on hydraulic resistance of erodible bed at the Chiyoda experimental flume  

NASA Astrophysics Data System (ADS)

The authors made erodible bed experiments under steady flow condition at the Chiyoda Experimental Flume, a large-scale facility constructed on the floodplain of the Tokachi River, and observed sand waves on the bed of the flume. In this study, the characteristics of the sand waves are examined along the longitudinal survey lines and confirmed to be dunes. Next, the authors estimated Manning's roughness coefficients from the observed hydraulic values and assumed that the rise of the coefficients attributed to the sand wave development. Finally, vertical flow distribution on the sand waves are examined, and observed velocity distribution on the crest of waves found to be explained by the logarithmic distribution theory.

Kakinuma, T.; Inoue, T.; Akahori, R.; Takeda, A.

2014-04-01

198

Serpentine Soil Redness, Differences among Peridotite and Serpentinite Materials, Klamath Mountains, California  

Microsoft Academic Search

Peridotite soils were perceived to be redder than serpentinite soils. These redness differences were confirmed by relating soil redness to bedrock specific gravities and to heavy mineral concentrations in fine sand fractions of soils. The redness differences are explained by mineralogical differences between peridotite and serpentinite. Soil redness in well-drained soils of the Klamath Mountains is closely related to free

E. B. Alexander

2004-01-01

199

Practice Hospital Bed Safety  

MedlinePLUS

... bed rails are suitable with any given bed frame." back to top Guidance FDA regulates hospital beds ... improved patient safety. "Manufacturers have redesigned their bed frames and their side rails to reduce the risk ...

200

Vent of Sand Volcano  

USGS Multimedia Gallery

Vent of sand volcano produced by liquefaction is about 4 ft across in strawberry field near Watsonville. Strip spanning vent is conduit for drip irrigation system. Furrow spacing is about 1.2 m (4 ft) on center....

2009-01-26

201

The Flow of Sand.  

ERIC Educational Resources Information Center

Describes a simple demonstration of the flow of sand through an orifice at the bottom of a sandbox. Advocates the experiment's use with dimensional analysis for students in an introductory physics course. (WRM)

Yersel, Metin

2000-01-01

202

Qualifying tight sands  

SciTech Connect

Qualifying parts of Kentucky's Big Sand gas field for tight sands designation will not be the only benefit to come out of the work now being done by the Kentucky Oil and Gas Association's Tight Sands Committee. The committee plans to evaluate all oil and gas producing formations in E. Kentucky for possible designation. Committee members are gathering detailed information on locations of wells, porosity and permeability of producing formations, and other production data within certain counties as part of the work required by the Federal Energy Regulatory Commission to determine areas for tight sands designation. These data are being entered into the computer system at the Kentucky Geological Survey, and will eventually be used to produce computerized planimetric maps.

Harbert, T.

1981-11-01

203

Sand on the Move  

NSDL National Science Digital Library

This site, from the National Park Service (NPS) and United States Geological Institute (USGS), gives a brief description of how sand dunes form. It describes how dunes will develop over time by repeating the processes of erosion, transportation, and deposition.

204

Great Sand Dunes.  

National Technical Information Service (NTIS)

Shows the 700-foot high dunes in their endless cycle of building and decaying, and explains in lay terms the geologic reasons for the dunes. Primary audience: visitors to Great Sand Dunes National Monument.

1994-01-01

205

Magic Sand Movie  

NSDL National Science Digital Library

This document from the Midwest Regional Center for Nanotechnology Education (NANO-LINK) is intended to be used with the other materials in the "magic sand" series of classroom lessons, which are available here. This resource is a 4 minute video demonstrating the magic sand experiment. In this experiment, students "will explore how the properties of a substance at the molecular level affects the way that it reacts and behaves."

2013-07-03

206

Sand Grain Observations  

NSDL National Science Digital Library

In this activity (on page 1 of the PDF), learners will use a magnifier to carefully examine samples of sand from different locations. They record their observations regarding the different grain characteristics to formulate their own explanations of where the sand came from, why the grains are jagged or smooth, and how they may have been sorted. Relates to the linked video, DragonflyTV GPS: Earthquakes.

Twin Cities Public Television, Inc.

2006-01-01

207

Use of microresistivity from the dipmeter to improve formation evaluation in thin sands, Northeast Kalimantan, Indonesia  

SciTech Connect

Estimation of reserves in lenticular reservoirs consisting of many thin-bedded sand/shale sequences is complicated by an overly pessimistic evaluation of sand count and hydrocarbon in place when conventional log interpretation techniques are used. It is probable that thin clean sand lenses have connected permeability. Their contribution to production should be considered in the estimation of reserves. An approach has been devised to improve the evaluation of thin clean sands by introducing accurate bed boundaries between sand and shale laminae as identified clearly on the dipmeter microresistivity curve processing presentation (GEODIP). Dipmeter data are integrated into conventional computer log analyses to yield more realistic estimates of porosity and hydrocarbon saturation throughout the reservoir. The method and the results attained to date are described.

Sallee, J.E.; Wood, B.R.

1984-09-01

208

Update on Regulation of Sand Transport in the Colorado River by Changes in the Surface Grain Size of Eddy Sandbars over Multiyear Timescales  

USGS Publications Warehouse

In settings where the transport of sand is partially or fully supply limited, changes in the upstream supply of sand are coupled to changes in the grain size of sand on the bed. In this manner, the transport of sand under the supply-limited case is ?grain-size regulated.? Since the closure of Glen Canyon Dam in 1963, the downstream reach of the Colorado River in Marble and Grand Canyons has exhibited evidence of sand-supply limitation. Sand transport in the river is now about equally regulated by changes in the discharge of water and changes in the grain sizes of sand on the channel bed and eddy sandbars. Previous work has shown that changes in the grain size of sand on the channel bed (driven by changes in the upstream supply of sand owing to both tributary floods and high dam releases) are important in regulating sand transport over timescales of days to months. In this study, suspended-sand data are analyzed in conjunction with bed grain-size data to determine whether changes in the sand grain size on the channel bed, or changes in the sand grain size on the surface of eddy sandbars, have been more important in regulating sand transport in the postdam Colorado River over longer, multiyear timescales. The results of this study show that this combined theory- and field-based approach can be used to deduce which environments in a complicated setting are most important for regulating sediment transport. In the case of the regulated Colorado River in Marble and upper Grand Canyons, suspended-sand transport has been regulated mostly by changes in the surface grain size of eddy sandbars.

Topping, David J.; Rubin, David M.; Schmidt, John C.

2008-01-01

209

Regulation of sand transport in the Colorado River by changes in the surface grain size of eddy sandbars over multi-year timescales  

USGS Publications Warehouse

In settings where the transport of sand is partially or fully supply limited, changes in the upstream supply of sand are coupled to changes in the grain size of sand on the bed. In this manner, the transport of sand under the supply-limited case is 'grain-size regulated'. Since the closure of Glen Canyon Dam in 1963, the downstream reach of the Colorado River in Marble and Grand Canyons has exhibited evidence of sand-supply limitation. Sand transport in the river is now approximately equally regulated by changes in the discharge of water and changes in the grain sizes of sand on the channel bed and eddy sandbars. Previous work has shown that changes in the grain size of sand on the bed of the channel (driven by changes in the upstream supply of sand owing to both tributary floods and high dam releases) are important in regulating sand transport over timescales of days to months. In this study, suspended-sand data are analysed in conjunction with bed grain-size data to determine whether changes in the grain size of sand on the bed of the channel or changes in the grain size of sand on the surface of eddy sandbars have been more important in regulating sand transport in the post-dam Colorado River over longer, multi-year timescales. The results of this study show that this combined theory- and field-based approach can be used to deduce which environments in a complicated setting are the most important environments for regulating sediment transport. In the case of the regulated Colorado River in Marble and Upper Grand Canyons, suspended-sand transport has been regulated mostly by changes in the surface grain size of eddy sandbars. ?? 2005 International Association of Sedimentologists.

Topping, D. J.; Rubin, D. M.; Schmidt, J. C.

2005-01-01

210

Drying of solids in fluidized beds  

SciTech Connect

Fluidized bed drying is advantageously adopted in industrial practice for drying of granular solids such as grains, fertilizers, chemicals, and minerals either for long shelf life or to facilitate further processing or handling. Solids are dried in batch and in continuous fluidized beds corresponding to cross-flow and countercurrent flow of phases covering a wide range in drying conditions. Materials that essentially dry with constant drying rate and then give a falling drying rate approximately linear with respect to solids moisture content (sand) as well as those with an extensive falling rate period with the subsequent falling rate being a curve with respect to the moisture content (mustard, ragi, poppy seeds) are chosen for the study. The performance of the continuous fluidized bed driers is compared with that of batch fluidized bed driers; the performance is predicted using batch kinetics, the residence time distribution of solids, and the contact efficiency between the phases.

Kannan, C.S.; Thomas, P.P.; Varma, Y.B.G. [Indian Inst. of Tech., Madras (India). Dept. of Chemical Engineering

1995-09-01

211

RUN OUTS OCCUR WHEN IRON HAS UNSEATED MOLDING SAND AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

RUN OUTS OCCUR WHEN IRON HAS UNSEATED MOLDING SAND AND RUN OUT OF THE MOLD UNDER POURING JACKETS AND SPILLS ONTO THE MOLDING PLATFORM. WORKERS GENERALLY WAIT SEVERAL MINUTES FOR THE IRON TO SOLIDIFY AND, WHILE IT IS STILL RED-HOT, REMOVE IT FROM THE PLATFORM AND SCRAP THE MOLD. - Southern Ductile Casting Company, Centerville Foundry, 101 Airport Road, Centreville, Bibb County, AL

212

In-bed circulating fluidized bed  

Microsoft Academic Search

Experience shows that fuel and bed material in a conventional vertically fluidized bed tends to mix within a maximum of a 6 to 10 square foot area. If the area is smaller, even better consistency is achieved. Thus, for each such increment of bed area, an additional feeder and ash extraction point are required. If not, the bed will not

Manicke

1984-01-01

213

The extraction of bitumen from western oil sands. Quarterly report, July--September, 1993  

SciTech Connect

This report cites task number followed by a brief statement of each task and the action taken this quarter. The tasks are: NEPA environmental information statement; coupled fluidized-bed bitumen recovery and coked sand combustion; water-based recovery of bitumen; rotary kiln process for recovery of bitumen and combustion of coke sand; recovery of bitumen from oil sands using fluidized bed reactors and combustion of spent sands in transport reactors; recovery of bitumen from oil sand and upgrading of bitumen by solvent extraction; catalytic and thermal upgrading of bitumens and bitumen-derived liquids; evaluation of Utah`s major oil sand deposits for the production of asphalt, high energy jet fuels, and other specialty products; development of mathematical models for bitumen recovery and processing; completion of the cost estimation study of the pilot plant restoration; development studies of equipment for three-product gravity separation of bitumen and sand; development studies of disposal of sand by conveying or pumping of high solids concentration sand-water slurries; and environmental studies of the North Salt Lake pilot plant rehabilitation and eventual operation and those environmental problems associated with eventual commercial products.

Oblad, A.G.; Bunger, J.W.; Dahlstrom, D.A.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1993-11-01

214

The role of suspended load transport in the occurrence of tidal sand waves  

NASA Astrophysics Data System (ADS)

sand waves are dynamic bed patterns which are formed by the complex interaction between hydrodynamics, sediment transport, and geomorphology. Field data from the southern North Sea reveal that sand waves are absent where suspended load transport is the dominant transport mode. In order to understand the mechanisms responsible for the absence of sand waves, we study the influence of suspended load transport on the formation of tidal sand waves with a numerical process-based geomorphological model (Delft3D). Model simulations are presented in which the vertical eddy viscosity and sediment diffusivity are both spatially and temporally variable (k-? turbulence model). First, it is shown that the preferred wavelength of sand waves for a relatively large grain size increases by the inclusion of suspended sediment, while for a relatively small grain size the flat bed is stable and no sand waves evolve. Second, it is shown that suspended load transport causes the suppression of long sand waves, resulting in a finite range of wavelengths that experience growth. Finally, by varying flow velocity amplitude and grain size, critical conditions for sand wave formation are found, i.e., conditions for which sand waves are marginally generated.

Borsje, B. W.; Kranenburg, W. M.; Roos, P. C.; Matthieu, J.; Hulscher, S. J. M. H.

2014-04-01

215

Characterization of Pressure Signals in Fluidized Beds Loaded with Large Particles Using Wigner Distribution Analysis: Feasibility of Diagnosis of Agglomeration  

Microsoft Academic Search

An experimental verification is reported on the early predicting index of agglomeration in bubbling fluidized bed. Coarse quartz sand, which has the same density but larger diameter than the bed material, was used to simulate the initial agglomerated particle. Wigner distribution was used to analyze the pressure fluctuation of the tested bed, and the average amplitude of local domain frequency

ZHANG Jiansheng; LÜ Junfu; WANG Xin; ZHANG Hai; YUE Guangxi; SUDA Toshiyuki; SATO Junichi

2007-01-01

216

Kentucky tar sand project  

SciTech Connect

Engineering details and pilot-plant results from a pioneering investigation based on a Kentucky tar-sand reserve are presented. The tar sand deposits of Kentucky are generally situated in the southeastern rim of the Illinois Basin along the southern boundary of the Western Coal Field region. In a recent study of US tar sand reserves, it was reported that over 3.4 billion barrels of oil are in Kentucky tar sand deposits alone. In the 22,000 acres, estimated reserves are over 100 million barrels of recoverable heavy oil. The oil-impregnated section of the deposit ranges in heavy oil content from five gallons per ton to over fifteen gallons per ton. The ore body is up to thirty-five feet thick and the overall stripping ratio for a commercial plant is estimated to be one cubic yard of undisturbed overburden material per ton of tar sand ore. A shovel and truck-type strip mining operation would be used to provide feedstock to the plant.

Kelley, M.N.; Jones, H.D. II; Lewis, F.W.

1985-03-01

217

Local solid mixing in gas–solid fluidized beds  

Microsoft Academic Search

Diffusivity of the solid particles in a 152-mm ID gas–solid fluidized bed was determined at different regimes of fluidization. The gas was air at room temperature and atmospheric pressure and the solids were 385 ?m sand or 70 ?m FCC particles. The experiments were done at superficial gas velocities from 0.5 to 2.8 m\\/s for sand and 0.44 to 0.9

Navid Mostoufi; Jamal Chaouki

2001-01-01

218

Perchlorate removal in sand and plastic media bioreactors  

Microsoft Academic Search

The treatment of perchlorate-contaminated groundwater was examined using two side-by-side pilot-scale fixed-bed bioreactors packed with sand or plastic media, and bioaugmented with the perchlorate-degrading bacterium Dechlorosoma sp. KJ. Groundwater containing perchlorate (77mg\\/L), nitrate (4 mg-NO3\\/L), and dissolved oxygen (7.5 mg\\/L) was amended with a carbon source (acetic acid) and nutrients (ammonium phosphate). Perchlorate was completely removed (o4mg\\/L) in the sand

Booki Mina; Patrick J. Evans; Allyson K. Chu; Bruce E. Logan

219

Perchlorate removal in sand and plastic media bioreactors  

Microsoft Academic Search

The treatment of perchlorate-contaminated groundwater was examined using two side-by-side pilot-scale fixed-bed bioreactors packed with sand or plastic media, and bioaugmented with the perchlorate-degrading bacterium Dechlorosoma sp. KJ. Groundwater containing perchlorate (77?g\\/L), nitrate (4mg-NO3\\/L), and dissolved oxygen (7.5mg\\/L) was amended with a carbon source (acetic acid) and nutrients (ammonium phosphate). Perchlorate was completely removed (<4?g\\/L) in the sand medium bioreactor

Booki Min; Patrick J Evans; Allyson K Chu; Bruce E Logan

2004-01-01

220

Incident angle of saltating particles in wind-blown sand.  

PubMed

Incident angle of saltating particles plays a very important role in aeolian events. In this paper, the incident angles of sand particles near the sand bed were measured in wind tunnel. It reveals that the incident angles range widely from 0° to 180° and thereby the means of angles are larger than published data. Surprisingly, it is found the proportion that angles of 5°-15° occupy is far below previous reports. The measuring height is probably the most important reason for the measurement differences between this study and previous investigations. PMID:23874470

Fu, Lin-Tao; Bo, Tian-Li; Gu, Hai-Hua; Zheng, Xiao-Jing

2013-01-01

221

BLAISDELL SLOW SAND FILTER WASHING MACHINE. VIEW LOOKING SOUTH. THE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BLAISDELL SLOW SAND FILTER WASHING MACHINE. VIEW LOOKING SOUTH. THE SUCTION (INTAKE) HOSE IS SEEN AT THE LEFT RESTING ON THE FILTER BED SURFACE; THE DISCHARGE HOSE IS AT THE RIGHT, RUNNING FROM THE BOTTOM OF THE CENTRAL VERTICAL AXLE TO THE CENTRIFUGAL PUMP. FROM THE PUMP WATER IS DISCHARGED THROUGH THE HORIZONTAL PIPE LOCATED UNDER THE EDGE OF PLATFORM DECK INTO THE WASTE-WATER TROUGH (NOT SEEN IN THIS VIEW). - Yuma Main Street Water Treatment Plant, Blaisdell Slow Sand Filter Washing Machine, Jones Street at foot of Main Street, Yuma, Yuma County, AZ

222

Measurements of the relationship between turbulence and sediment in suspension over mobile sand dunes in a laboratory flume  

Microsoft Academic Search

The relationship between fluid and particle motions over a mobile dune bed was investigated using a laboratory flume with mobile sand dunes. Fluid turbulence data from a laser Doppler velocimeter (LDV) and suspended-sediment data from an acoustic backscatter system (BSS) were collected from the same sampling volume at a constant position relative to passing sand dunes in a laboratory channel

D. G. Wren; R. A. Kuhnle; C. G. Wilson

2007-01-01

223

Red Tides  

NSDL National Science Digital Library

This comprehensive website answers questions such as: what is red tide, where are they found, why do they occur, how do they affect marine organisms, how do they affect humans, how are shellfish tested for the toxin, and what is being done to remediate the red tide problem. The site features color pictures and black and white maps.

Communications Directorate, Department O.

224

Asbestos in play sand  

SciTech Connect

A letter in the New England Journal of Medicine (Oct. 2 issue) stated that a carbonate sand marketed in New Jersey was contaminated with 2 to 4 percent tremolite asbestos. The authors were called on by one of the federal agencies to repeat the analysis of this sand, specifically for its asbestos content. The sand was pulverized and immersed in oils with known refractive indexes, and the predominant amphibole was characterized by polarized light microscopy. The optical characteristics were noted, and the indexes of refraction were measured and found to be consistent with tremolite. On the basis of optical characterization, the authors concluded that all the tremolite visualized with light microscopy consisted of large, single cleavage fragments and was not asbestiform. They used the technique of x-ray diffraction, as did the author of the original report, which showed the presence of an amphibole mineral (probably tremolite) in the carbonate sand. The technique was not used, and cannot be used, to distinguish between the tremolite habits (asbestiform or nonasbestiform). An acid-insoluble residue, recovered from the carbonate sand, was examined by analytic electron microscopy. The tremolite grains were observed to consist of single untwinned, crystalline fragments. Few defects were noted. Selected area electron diffraction nets were indicative of fragments lying near or at the common amphibole cleavage plane. These characteristics are consistent with cleavage fragments and not asbestos. Aspect ratios reflected short particles (less than 5.1). On the basis of their examination of the carbonate play sand, they conclude that it did not contain tremolite asbestos.

Langer, A.M.; Nolan, R.P.

1987-04-02

225

Sound-Producing Sand Avalanches  

NSDL National Science Digital Library

This site presents an analysis of the theories and experiments done so far on sound-producing (e.g., roaring, booming) sand avalanches. Several reference articles are cited, and a link to the summary of an article, "Booming Sand", in Scientific American volume 277, number 3, is provided. An on site version of another article, "Sound Producing Sand Avalanches", in Contemporary Physics, volume 38, number 5, is also presented in three different formats: PDF, HTML, and Postscript Preprint.The other main features of this site are sound recordings of booming sand, compressed squeaking sand, and croaking sand, as well as, and images and micrographs of booming dunes.

Bretz, Michael; Nori, Franco; Sholtz, Paul

2007-05-18

226

A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change  

USGS Publications Warehouse

Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.

Grams, Paul E.

2013-01-01

227

CADMIUM EFFECTS ON THE NITROGEN FIXATION SYSTEM OF RED ALDER  

EPA Science Inventory

Red alder (Alnus rubra) was grown in sand culture in the greenhouse to obtain data on the effects of cadmium (Cd) on a symbiotic nitrogen (N) fixation system which contributes to the fertility of forest soils. Treatment of red alder seedlings for 11 weeks with 0.545 to 136 microm...

228

Collapsing granular beds: The role of interstitial air  

NASA Astrophysics Data System (ADS)

A prefluidized sand bed consisting of fine particles compactifies when it is subjected to a shock. We observe that the response depends on both the shock strength and the ambient pressure, where, counterintuitively, at high ambient pressure the compaction is larger, which we connect to a decrease of the static friction inside the bed. We find that the interstitial air is trapped inside the bed during and long after compaction. We deduce this from measuring the pressure changes above and below the bed: The top pressure decreases abruptly, on the time scale of the compaction, whereas that below the bed slowly rises to a maximum. Subsequently, both gently relax to ambient values. We formulate a one-dimensional diffusion model that uses only the change in bed height and the ambient pressure as an input, and we show that it leads to a fully quantitative understanding of the measured pressure variations.

Homan, Tess; Gjaltema, Christa; van der Meer, Devaraj

2014-05-01

229

Red Sky with Red Mesa  

ScienceCinema

The Red Sky/Red Mesa supercomputing platform dramatically reduces the time required to simulate complex fuel models, from 4-6 months to just 4 weeks, allowing researchers to accelerate the pace at which they can address these complex problems. Its speed also reduces the need for laboratory and field testing, allowing for energy reduction far beyond data center walls.

None

2014-06-23

230

Red Sky with Red Mesa  

ScienceCinema

With those fossil fuel reserves dwindling, the scientific race is on to convert the sunlight harvested by plants into new fuels that will augment and eventually replace petroleum. It's a critical challenge. But there is a powerful tool tackling it: Sandia National Laboratories' Red Sky Supercomputer with a special cluster called Red Mesa dedicated specifically to the National Renewable Energy Laboratory (NREL).

None

2013-05-29

231

Red Sky with Red Mesa  

SciTech Connect

The Red Sky/Red Mesa supercomputing platform dramatically reduces the time required to simulate complex fuel models, from 4-6 months to just 4 weeks, allowing researchers to accelerate the pace at which they can address these complex problems. Its speed also reduces the need for laboratory and field testing, allowing for energy reduction far beyond data center walls.

None

2011-04-14

232

Red Sky with Red Mesa  

SciTech Connect

With those fossil fuel reserves dwindling, the scientific race is on to convert the sunlight harvested by plants into new fuels that will augment and eventually replace petroleum. It's a critical challenge. But there is a powerful tool tackling it: Sandia National Laboratories' Red Sky Supercomputer with a special cluster called Red Mesa dedicated specifically to the National Renewable Energy Laboratory (NREL).

None

2011-01-01

233

Modern analog for deep-water deposition of shallow-water Pliocene Sands, Gulf of Mexico  

SciTech Connect

Paleoenvironmental studies using benthic foraminifers and total fauna can be used to identify displaced shallow-water sands. A productive sand in Eugene Island field, which has a high resistivity but suppressed spontaneous-potential, was conventionally cored to determine reservoir characteristics and environment of deposition. Grain-size analysis shows a composition of very fine sand with a large silt and clay component. Studies of sand-size distribution throughout the 13-ft core did not reveal graded bedding, thus excluding turbidity currents as a depositional mechanism. Analysis of the benthic fauna within the sand unit indicates that the sands and thin-bedded shales were originally deposited on the inner to middle shelf. The occurrence of bathyal shale above and below the productive unit suggests that the shallow-water sands were transported basinward into a slope environment. Regional paleobathymetric maps indicate that there was a progradation of the shelf edge during deposition of the sand unit. This evidence, along with the fine-grained character of the sands, suggests that a deltaic complex was developing updip of the field. The depositional environment is very similar to that described by J.M. Coleman and others near the modern Mississippi River Delta. The processes that are moving shallow-water sands across the shelf, stimulating mass movement and shelf-ridge slumping, were also active around ancient deltas. Based on the modern analog, it is interpreted that the field sand is part of a debris flow initiated by shelf-edge failure. The geometry of the sand unit also supports this hypothesis.

Kohl, B.

1985-02-01

234

Oil from deep sands  

Microsoft Academic Search

Near Cold Lake, in NE Alberta, Esso Resources Canada Ltd. proposes to build a massive commercial plant to tap rich reserves of bitumen, or heavy oil, buried deep in sands approximately 1600 ft below the ground. The in situ steam injection extraction technique which is planned has been tested in pilot plants at the site for the past 17 yr.

2009-01-01

235

Sand and sandstone  

SciTech Connect

Here is a new, second edition of a classical textbook in sedimentology, petrology, and petrography of sand and sandstones. It has been extensively revised and updated, including: new techniques and their utility; new literature; new illustrations; new, explicitly stated problems for the student; and a wider scope.

Pettijohn, F.J.; Potter, P.E.; Siever, R.

1987-01-01

236

Sand and gravel  

Microsoft Academic Search

Sand and gravel are, and will continue to be, among the most important construction and industrial materials in the United States. It is the only mineral commodity produced in all 50 States. It is the principal ingredient in many houses, office buildings, highways, dams, airport runways, bridges, canals, and in glass for bottles and house and automobile windows. Also, it

J. R. Evans

1978-01-01

237

Ganges Chasma Sands  

NASA Technical Reports Server (NTRS)

8 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, windblown sand in the form of dunes and a broad, relatively flat, sand sheet in Ganges Chasma, part of the eastern Valles Marineris trough complex. The winds responsible for these dunes blew largely from the north. Sand dunes on Mars, unlike their Earthly counterparts, are usually dark in tone. This is a reflection of their composition, which includes minerals that are more rich in iron and magnesium than the common silica-rich dunes of Earth. Similar dark sands on Earth are found in volcanic regions such as Iceland and Hawaii. A large dune field of iron/magnesium-rich grains, in the form fragments of the volcanic rock, basalt, occurs south of Moses Lake, Washington, in the U.S.

Location near: 7.7oS, 45.3oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

2005-01-01

238

Northern Sand Sea  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form.

This VIS image was taken at 82 degrees North latitude during Northern spring. The image is completely dominated by dunes. In sand seas, it is very common for a single type of dune to occur, and for a single predominate wind to control the alignment of the dunes.

Image information: VIS instrument. Latitude 82.2, Longitude 152.5 East (207.5 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2005-01-01

239

Packed Bed Reactor Experiment  

NASA Video Gallery

The purpose of the Packed Bed Reactor Experiment in low gravity is to determine how a mixture of gas and liquid flows through a packed bed in reduced gravity. A packed bed consists of a metal pipe ...

240

Biological Processing Capacities and Biomass Growth in Waste Water Treatment by Infiltration On two Kinds of Sand  

Microsoft Academic Search

In this article, work is presented which highlights the biological processing capacities of urban waste water within porous media of different textures. A comparative study on the growth of biomass coupled with the general mechanisms for gas transfer through two biological beds is undertaken. Infiltration-percolation beds are simulated using columns filled with sands of different origins and structures. These are

Adrien Wanko; Robert Mose; Christian Beck

2005-01-01

241

Coal quality in area of Sand Mountain and Lookout Mountain, southern Appalachian Mountains, Georgia, Tennessee, and Alabama  

Microsoft Academic Search

More than 10 coal beds of Pennsylvanian age crop out around Sand Mountain and Lookout Mountain in Georgia, Tennessee, and Alabama. These beds were deposited in barrier and fluvial environments. Few determinations of modern coal-quality data have been made for these coals, although they have been mined for more than 100 years. To evaluate their quality, 47 coal samples from

T. L. Crawford

1986-01-01

242

Oil sands fulfill their promise  

Microsoft Academic Search

The Great Canadian Oil Sands plant, a $300 million investment for Sun Oil Co., is the first commercial facility to wrest oil from the Alberta tar sands. Energy companies are poised to invest more than $3 billion in oil sands development in the next several years. Construction already underway, planning for projects to come, and the widening scope of oil

Chaapel

2009-01-01

243

Special report: Athabasca tar sands  

Microsoft Academic Search

A synthetic crude oil is being produced from the Athabasca oil sands region of northeastern Alberta. The Athabasca operations are broken down into 3 divisions: mining, extraction of oil from the sand, and pipelining to market. The entire project, operated by Great Canadian Oil Sands, Ltd., an affiliate of Sun Oil Co., is self-sufficient except for the water supply. By-

W. A. Bachman; D. H. Stormont

1967-01-01

244

Sand accumulation around porous fences  

Microsoft Academic Search

A computer model is developed to calculate the average monthly and annual rates of potential sand drift over a specific study area. The basic formula adopted for calculating potential sand drift due to wind blowing in a certain direction, speed and height above the drifted surface is given by Bagnold (1936, 1954). The accumulated sand profiles with time, around a

Nabil A. Zaghloul

1997-01-01

245

Red yeast  

MedlinePLUS

... with this combination.Talk with your health provider.Cyclosporine (Neoral, Sandimmune)Red yeast might affect the muscles. Cyclosporine (Neoral, Sandimmune) might also affect the muscles. Taking ...

246

Rhodolith bed: a newly discovered habitat in the North Pacific Ocean  

Microsoft Academic Search

Rhodoliths are unattached calcareous red algae that form extensive beds. Although rhodolith beds are widely dis- tributed in temperate and tropical areas, a recent discov- ery in the North Pacific Ocean represents a significant northward extension of known rhodolith distribution. This bed, located in Prince William Sound, Alaska, is com- posed of one rhodolith species, Phymatolithon calca- reum, with two

Brenda Konar; Rafael Riosmena-Rodriguez; Katrin Iken

2006-01-01

247

Sheet flow and suspension of sand in oscillatory boundary layers  

Microsoft Academic Search

after revisionTime-dependent measurements of flow velocities and sediment concentrations were conducted in a large oscillating water tunnel. The measurements were aimed at the flow and sediment dynamics in and above an oscillatory boundary layer in plane bed and sheet-flow conditions. Two asymmetric waves and one sinusoidal wave were imposed using quartz sand with D50 = 0.21 mm. A new electro-resistance

Jan S. Ribberink; Abdullah A. Al-Salem

1995-01-01

248

The Rheology of Acoustically Fluidized Sand  

NASA Astrophysics Data System (ADS)

The collapse of large craters and the formation of central peaks and peak rings is well modeled by numerical computer codes that incorporate the acoustic fluidization mechanism to temporarily allow the fluid-like flow of rock debris immediately after crater excavation. Furthermore, long runout landslides require a similar mechanism to explain their almost frictionless movement, which is probably also a consequence of their granular composition coupled with internal vibrations. Many different investigators have now confirmed the ability of vibrations to fluidize granular materials. Yet it still remains to fully describe the rheology of vibrated sand as a function of stress, frequency and amplitude of the vibrations in the sand itself. We constructed a rotational viscometer to quantitatively investigate the relation between the stress and strain rate in a horizontal bed of strongly vibrated sand. In addition to the macroscopic stain rate, the amplitude and frequency of the vibrations produced by a pair of pneumatic vibrators were also measured with the aid of miniaturized piezoelectric accelerometers (B&K 4393) whose output was recorded on a digital storage oscilloscope. The initial gathering of the experimental data was difficult due to granular memory, but by having the sand compacted vibrationally for 8 minutes before each run the scatter of data was reduced and we were able to obtain consistent results. Nevertheless, our major source of uncertainty was variations in strain rate from run to run. We find that vibrated sand flows like a highly non-Newtonian fluid, in which the shear strain rate is proportional to stress to a power much greater than one, where the precise power depends on the amplitude and frequency of the applied vibrations. Rapid flow occurs at stresses less than half of the static yield stress (that is, the yield stress when no vibration is applied) when strong vibrations are present. For a Newtonian fluid, such as water, the relation between strain rate and stress is linear. In our experiments we found that the shear strain rate is proportional to shear stress raised to the powers 5.9 and 8.4 at frequencies of 8.5 kHz and 7.4 kHz and increasing amplitude of vibration, respectively. This demonstrates that vibrated sand behaves as a strongly nonlinear pseudo-plastic material that, like glacier ice, can also be approximated as a Bingham material with a rate-dependent yield stress. The flow of acoustically fluidized granular materials provides a reasonable explanation of crater collapse, long runout landslides, and other events involving large masses of granular material.

Conrad, J. W.; Melosh, J.

2013-12-01

249

National Metal Casting Research Institute final report. Volume 1, Sand reclamation  

SciTech Connect

A mobile thermal foundry sand reclamation unit was designed and constructed. This unit consisted of thermal and mechanical sand reclamation equipment installed on the bed of a 50 foot low-boy trailer. It was transported to a number of Midwest foundries for on-site demonstration of the sand reclamation process. This allowed participating foundries to have their own refuse sand (10-100 tons) processed and then reused in production for evaluation. The purpose for building the unit was to demonstrate to foundries through ``hands on`` experience that refuse sands can be reclaimed and successfully reused particularly in regard to product quality. Most of the participating foundries indicated a high level of satisfaction with the reclaimed sand. Laboratory testing of samples of the used sand, before and after processing by the demonstration unit, verified the usability of the reclaimed sand. One of the foundries participating was a brass foundry, the sand from this foundry contained lead and is classified as a hazardous material. After reclamation the sand was no longer hazardous and could also be reused in the foundry.

Vondra, L.F.; Burningham, J.S. [University of Northern Iowa, Cedar Falls, IA (United States). Dept. of Industrial Technology

1995-08-01

250

Sand hazards on tourist beaches.  

PubMed

Visiting the beach is a popular tourist activity worldwide. Unfortunately, the beach environment is abundant with hazards and potential danger to the unsuspecting tourist. While the traditional focus of beach safety has been water safety oriented, there is growing concern about the risks posed by the sand environment on beaches. This study reports on the death and near death experience of eight tourists in the collapse of sand holes, sand dunes, and sand tunnels. Each incident occurred suddenly and the complete burial in sand directly contributed to the victims injury or death in each case report. PMID:23290717

Heggie, Travis W

2013-01-01

251

Flow structure of the solids in gas–solid fluidized beds  

Microsoft Academic Search

Existence of clusters in dense fluidized beds was investigated by analyzing the time-position data of a tracer obtained in several radioactive particle tracking experiments. It was found that in the case of sand particles, more gas passes through the bed as bubbles with increasing the superficial gas velocity and in the case of FCC powder, flow of the gas through

Navid Mostoufi; Jamal Chaouki

2004-01-01

252

Textural trends in turbidites and slurry beds from the Oligocene flysch of the East Carpathians, Romania  

Microsoft Academic Search

Deep-water sandstone beds of the Oligocene Fusaru Sandstone and Lower Dysodilic Shale, exposed in the Buza ùu Valley area of the East Carpathian flysch belt, Romania, can be described in terms of the standard turbidite divisions. In addition, mud-rich sand layers are common, both as parts of otherwise 'normal' sequences of turbidite divisions and as individual event beds. Eleven units,

Zoltan Sylvester; Donald R. Lowe

2004-01-01

253

Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-495, 26 September 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows windblown sand dunes in Chasma Boreale, a wide trough in the north polar region of Mars. The dunes are shown here in their summertime configuration; that is, they are not covered with seasonal frost. The dunes are dark because the grains that make up these sandy landforms consist of dark minerals and/or fragments of dark-toned rock. The steepest slopes on these dunes, their slipfaces, point toward the top/upper left (northwest), indicating that winds blow the sand from the lower right (southeast). This picture is located near 84.7oN, 359.3oW, and covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

2003-01-01

254

Magic Sand: Nanosurfaces  

NSDL National Science Digital Library

This is an activity/demo in which learners are exposed to the difference bewteen hydrophobic surfaces (water repelling) and hydrophilic surfaces (water loving). This activity also demonstrates how changing the size of material to nanoscale changes its behavior at the macroscale. The instructions assume that Magic Sand is performed as a demonstration, but it works great a a hands-on activity as well.

Network, Nanoscle I.; Wisconsin-Madison, University O.

2012-06-26

255

Western gas sands  

SciTech Connect

The purpose of this research is to demonstrate the feasibility of economically producing natural gas from low-permeability reservoirs. Two broad research goals have been defined: (1) reducing the uncertainty of the reservoir production potential, and (2) improving the extraction technology. These goals are being pursued by conducting research and encouraging industrial efforts in developing the necessary technology, including: (1) providing fundamental research into the nature of tight, lenticular gas sands and the technologies for diagnosing and developing them: (2) developing and verifying the technology for effective gas production; and (3) promoting the transfer of research products and technology advances to the gas industry in usable forms. The focus of the research for the last several years has been improving diagnostic instrumentation for reservoir and stimulation performance evaluation, geophysical and engineering interpretation, and stimulation techniques. Integrated geologic studies of three basins containing tight lenticular sands, which were selected by DOE as priority research targets, have also been pursued as part of this new effort. To date, the following tentative conclusions have been formed: Permeability of the tight gas sands can be as much as three to four orders of magnitude lower than that of conventional gas deposits. Nineteen western geologic basins and trends containing significant volumes of tight gas have been identified. Gas resources in the priority geologic basins have been estimated - Piceance Basin 49 Tcf.; Greater Green River Basin, 136 Tcf.; Uinta Basin, 20 Tcf. Presence of natural micro-fractures within a reservoir and the effective propped length of hydraulically induced fratures are the critical parameters for successful development of tight sand resources. Stimulation technology at the present time is insufficient to efficiently recover gas from lenticular tight reservoirs. 8 figs., 3 tabs.

Not Available

1985-03-01

256

Pressure Fluctuations as a Diagnostic Tool for Fluidized Beds.  

National Technical Information Service (NTIS)

The validity of using bubbling fluidized bed (BFB) similitude parameters to match a hot BFB to a cold BFB is being studied. Sand in a BFB combustor and copper powder in cold BFB model have been analyzed and found to be out of similitude. In the analysis p...

R. C. Brown J. R. Schroeder

1997-01-01

257

Retention of Airborne Particles in Granular Bed Filters.  

National Technical Information Service (NTIS)

A literature survey was made on theoretical models for the prediction of particle retention in sand beds. Also data on observed retention was collected from the literature. Based on this information, a semi-empirical model was compiled. Comparison of the ...

L. Stroem

1981-01-01

258

Fluidized bed combustion  

SciTech Connect

The invention relates to fluidized bed combustors that might tilt in use so that the depth of the bed progressively changes across its width. Air is supplied from two or more sources and means are provided to vary the flow from the sources as the bed tilts so that the air supplied to the portion of the bed of increased depth is increased relatively to the air supplied to the portion of the bed of lesser depth.

Hodgkin, A.F.

1980-12-16

259

Spontaneous Emergence of Order in Vibrated Sand*  

NASA Astrophysics Data System (ADS)

Granular media such as sand, pharmaceuticals, cereal, cosmetics, and asteroids are involved in many processes, yet granular media remain less well understood than fluids and solids. Vertically oscillating granular layers provide a test bed for theory and modeling of granular dynamics. Experiments on vertically oscillating granular layers have revealed a variety of spatial patterns that emerge spontaneously as a function of the container acceleration amplitude and frequency: stripes, squares, hexagons, spirals, and oscillons (localized structures). Molecular dynamics simulations yield results in quantitative accord with laboratory observations. Since the gradients of density and velocity are large over a particle mean free path, the applicability of continuum theory has been questionable. However, hydrodynamic equations proposed for dissipative particles yield results in surprising qualitative accord with the laboratory observations. *Work in collaboration with C. Bizon, D. Goldman, W.D. McCormick, S.J. Moon, E. Rericha, M. Shattuck, and J. Swift. Supported by DOE.

Swinney, Harry L.

2004-05-01

260

Reconnaissance examination of selected oil-sand outcrops in Wyoming  

SciTech Connect

Numerous surface occurrences of oil sands and oil seeps have been reported in the geologic literature for Wyoming. Seventy-eight reported occurrences are listed in Wyoming Geological Survey Open-File Report 82-5. Most of the listed deposits are taken from old references with vague descriptions and locations. Field reconnaissance examinations of selected oil-sand occurrences were conducted to describe them better and to assess their potential economic importance. A reconnaissance geologic map of each examined deposit was constructed, and the deposits were sampled and described. Ten occurrences were described during the 1984 and 1985 field seasons. The oil-sand occurrences were all sandstone reservoirs ranging from Pennsylvanian to Tertiary. Based on these reconnaissance examinations, only three occurrences appeared to be potentially significant. The Rattlesnake Hills occurrence, west of Casper, is an asymmetrical anticline with oil-impregnated sands in the Mesaverde Formation, Frontier Formation, and, most extensively, the Muddy Sandstone. Other formations in the structure contain minor amounts of oil staining. The Muddy Creek occurrence, southwest of Rawlins, contains oil-impregnated sandstones in the lower Wasatch Formation. This stratigraphically controlled trap dips to the west into the Washakie basin. The Conant Creek occurrence, southeast of Riverton, includes stratigraphically controlled oil sands in the relatively flat Wagon Bed Formation.

Ver Ploeg, A.

1986-08-01

261

Interpretation of very thin gas sands in Italy  

SciTech Connect

In North Eastern Italy large production of gas is obtained from very thin sands inter-laminated with shales. Normal interpretation methods fail because the sand thickness may be as low as one or two inches and invasion is often rather deep. A satisfactory interpretation method must provide: detection of each individual sand, qualitative gas indication, and a running average evaluation of porosity. In order to provide the necessary information the logs should be recorded at 1.2'' sampling rate and have high vertical resolution: thus the Electromagnetic Propagation log and a Micro-Resistivity should be included. As an absolute minimum, the Dipmeter curves can be used to define individual beds. A simple method, based on cut-offs on the Electromagnetic Attenuation or Resistivity curve, can be used to distinguish the sands; however a much better detection is obtained from a pattern recognition method using the shape of the above curves rather than their absolute value. This can normally recognize individual sands down to less than 2'' thickness.

Suau, J.; Alberetelli, L.; Cigni, M.

1984-01-01

262

Recovery of oil from Utah's Tar Sands. Final report, December 1, 1979-March 31, 1983  

SciTech Connect

Work was focused in the following main areas: water assisted extraction of bitumens, quality and disposal of tailings, and raw bitumen clean-up; thermal recovery of bitumens in a fluidized-bed characterization of bitumen obtained and coked sand combustion; recovery of heat from hot burned sand; upgrading of raw bitumens from water extraction and thermally produced bitumens including in situ recovered material. This report covers in particular the following: investigation of the effect of bitumen viscosity in hot water extraction of tar sands and bitumen concentrate cleaning and a study of the use of an air sparged hydroclone in bitumen recovery; thermal recovery of bitumen from two additional Utah tar sands: Tar Sand Triangle and Whiterocks; upgrading of tar sand bitumens by the processing sequences; coking followed by hydrotreating of product and hydropyrolysis followed by hydrotreating of product; experimental and theoretical studies of a fluidized-bed pyrolysis reactor with a coked sand combination reactor with transfer of heat from the combustor to the pyrolysis reactor by means of potassium filled heat pipe.

Oblad, A.G.; Bunger, J.W.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1984-01-01

263

Sand dollar sites orogenesis  

NASA Astrophysics Data System (ADS)

The determinology of the humble sand dollars habitat changing from inception to the drastic evolution of the zone to that of present day. Into the cauldron along the southern Californian 'ring of fire' lithosphere are evidence of geosynclinals areas, metasedimentary rock formations and hydrothermal activity. The explanation begins with 'Theia' and the Moon's formation, battles with cometary impacts, glacial ages, epochs with evolutionary bottlenecks and plate tectonics. Fully illustrated the lecture includes localised diagrams and figures with actual subject photographic examples of plutonic, granitic, jade and peridodite. Finally, the origins of the materials used in the lecture are revealed for prosecution by future students and the enjoyment of interested parties in general.

Amos, Dee

2013-04-01

264

Imperial Sand Dunes  

NSDL National Science Digital Library

The Bureau of Land Management presents the current news, projects, and the geologic and cultural history of the Imperial Sand Dunes at this website. Users can easily search through an abundance of remarkable images of dunes as well as other Californian landscapes. The website offers links to the current rules, regulations, and management plans. Individuals, who will be traveling to the area, can find the weather forecast, an events calendar, and information on volunteering. Visitors can locate archives of Federal Register Notices as well as news releases.

265

Process sedimentology and reservoir quality of deep-marine bottom-current reworked sands (sandy contourites): An example from the Gulf of Mexico  

SciTech Connect

Deep-marine bottom-current reworked sands (sandy contourites) have been recognized in hydrocarbon-bearing sands of the Gulf of Mexico. A distinctive attribute of these sands is their traction bed forms, which occur in discrete units. Common sedimentary features of traction currents include cross-bedding, current ripples, horizontal lamination, sharp upper contacts, and inverse size grading. These sands also exhibit internal erosional surfaces and mud offshoots, indicating oscillating current energy conditions. THe Pliocene-Pleistocene sequence cored in the Ewing Bank Block 826 field in the Gulf of Mexico provides an example of sand distribution and reservoir quality of deep-marine bottom-current reworked sands. Presumably, the Loop Current, a strong wind-driven surface current in the Gulf of Mexico, impinged on the sea bottom, as it does today, and resulted in bottom-current reworked sands. A depositional model based on the integration of well (core and log) and three-dimensional seismic data suggests that the reworked sediment package may be thick and continuous, but individual sand layers within the package may be thin and discontinuous. This unconventional model, which depicts the distribution of bottom-current reworked sands in interchannel slope areas as a distinctly different facies from channel-levee facies, has the potential for general application to other slope plays outside the study area. In the Ewing Bank Block 826 field, the type I (L-1) reservoir with 80% sand exhibits higher permeability values (100-1800 md) than the type 2 (N-1) reservoir with 26% sand (50-800 md). The increased permeability in the type I sand has been attributed to high sand content, vigorous reworking, and microfractures. The clean, porous, and well-sorted type 1 sands with good communication between sand layers have produced at higher rates and recovery efficiencies than the type 2 sands with numerous interbedded mud layers. 50 refs., 22 figs., 1 tab.

Shanmugam, G. (Mobil Research and Development Corp., Dallas, TX (United States)); Spalding, T.D.; Rofheart, D.H. (Mobil New Business Development, Dallas, TX (United States))

1993-07-01

266

Red blood cell decreases of microgravity  

NASA Technical Reports Server (NTRS)

Postflight decreases in red blood cell mass (RBCM) have regularly been recorded after exposure to microgravity. These 5-25 percent decreases do not relate to the mission duration, workload, caloric intake or to the type of spacecraft used. The decrease is accompanied by normal red cell survivals, increased ferritin levels, normal radioactive iron studies, and increases in mean red blood cell volume. Comparable decreases in red blood cell mass are not found after bed rest, a commonly used simulation of the microgravity state. Inhibited bone marrow erythropoiesis has not been proven to date, although reticulocyte numbers in the peripheral circulation are decreased about 50 percent. To date, the cause of the microgravity induced decreases in RBCM is unknown. Increased splenic trapping of circulating red blood cells seem the most logical way to explain the results obtained.

Johnson, P. C.

1985-01-01

267

Depositional environments, reservoir trends, and diagenesis of Red Fork sandstones in parts of Blaine, Caddo, and Custer counties, Oklahoma  

Microsoft Academic Search

The Red Fork sandstone was divided into the upper and lower Red Fork which are separated by a consistent marker bed. The Red Fork interval thickens markedly across the study area from 250 ft (75 m) in the northeast to over 1300 ft (400 m) in the southwest. Most of the thickening is within the lower Red Fork. The lower

Christopher L. Johnson

1984-01-01

268

Size distribution of Amazon River bed sediment  

USGS Publications Warehouse

The first recorded observations of bed material of the Amazon River were made in 1843 by Lt William Lewis Herndon of the US Navy, when he travelled the river from its headwaters to its mouth, sounding its depths, and noting the nature of particles caught in a heavy grease smeared to the bottom of his sounding weight1. He reported the bed material of the river to be mostly sand and fine gravel. Oltman and Ames took samples at a few locations in 1963 and 1964, and reported the bed material at O??bidos, Brazil, to be fine sands, with median diameters ranging from 0.15 to 0.25 mm (ref. 2). We present here a summary of particle-size analyses of samples of streambed material collected from the Amazon River and its major tributaries along a reach of the river from Iquitos in Peru, ???3,500 km above Macapa?? Brazil, to a point 220 km above Macapa??3. ?? 1980 Nature Publishing Group.

Nordin, C. F.; Meade, R. H.; Curtis, W. F.; Bosio, N. J.; Landim, P. M. B.

1980-01-01

269

Carbonate eolianites, quartz sands, and Quaternary sea-level cycles, Western Australia: A chronostratigraphic approach  

Microsoft Academic Search

Marine and eolian carbonate deposits, grouped under the name “Tamala Limestone”, have been investigated along thousands of kilometers of coastal Western Australia (WA). Relative-age diagenetic features of carbonate sand dunes or “eolianites” indicate that coastal ridges decrease in age seaward, reflecting coastal accretion during successive sea-level stands. Yellow- to red-stained quartz sands are associated with eolianites as pits, lenses, extensive

Paul J. Hearty; Michael J. O’Leary

2008-01-01

270

Phosphorus accummulation in reed bed treatment filter  

NASA Astrophysics Data System (ADS)

Introduction Constructed wetlands are well known method for alternative wastewater treatment in rural areas in Poland. There are mainly used as a biological treatment step of domestic wastewater. The most popular are subsurface flow constructed wetlands (reed bed systems) with bed filled with site soil (mainly clayey sand or sandy clay). Over 30 such plants with daily flow above 5 m3 per day is operated in Poland. Object and goal of research Many researches have been made on estimation constructed wetlands treatment efficiency, however there are mostly concentrated on inlet outlet concentration compartments. In this study preliminary results of phosphorus accumulation in the bed of horizontal subsurface flow constructed wetland are presented. Monitored plant treats wastewater from 150 inhabitants in the volume of 14 m3 d-1 at average and is under operation from December 1998. The goal of research was to asses the distribution of phosphorus in the wetland bed after 8 years of treatment of domestic wastewater. Obtained results are shown on the background of organic matter (TOC) distribution. The methods applied The bed of the constructed wetland (30 m width and 33 m length) was divided by net of 20 points. In every point two soil samples, one from the depth of 0-10 cm and one from the depth of 20-30 cm, were collected. The samples were analyzed for organic matter and total phosphorus content. Investigation findings The results showed variation of measured indexes on the length and depth of treatment bed. In generally, the highest accumulation occurred near the inlet zone of wetland. The relation is rather clear in case of organic matter, but in case of phosphorus high contents were also observed at the outlet zone of wetland. Higher organic matter concentrations were observed in deeper layer (20-30 cm) than in upper layer (0-10 cm) of the bed.

Karczmarczyk, A.; Bary?a, A.

2009-04-01

271

Vacuum Head Removes Sanding Dust  

NASA Technical Reports Server (NTRS)

Vacuum sander prevents sanding dust from entering a work area, since dust particles are drawn off as quickly as they are produced. Tool is useful where dust presents health hazards, interferes with such processes as semiconductor manufacture, or could destroy wet paint or varnish finishes. Could be used to sand such materials as lead paint.

Bengle, C. G.; Holt, J. W.

1982-01-01

272

Sand and Dust on Mars  

NASA Technical Reports Server (NTRS)

Mars is a planet of high scientific interest. Various studies are currently being made that involve vehicles that have landed on Mars. Because Mars is known to experience frequent wind storms, mission planners and engineers require knowledge of the physical and chemical properties of Martian windblown sand and dust, and the processes involved in the origin and evolution of sand and dust storms.

Greeley, Ronald; Haberle, Robert M.

1991-01-01

273

Submarine sand volcanos: experiments and numerical modelling  

NASA Astrophysics Data System (ADS)

Fluid overpressure at the bottom of a soil layer may generate fracturation in preferential paths for a cohesive material. But the case of sandy soils is rather different: a significant internal flow is allowed within the material and can potentially induce hydro-mechanical instabilities whose most common example is fluidization. Many works have been devoted to fluidization but very few have the issue of initiation and development of a fluidized zone inside a granular bed, prior entire fluidization of the medium. In this contribution, we report experimental results and numerical simulations on a model system of immersed sand volcanos generated by a localized upward spring of liquid, injected at constant flow-rate at the bottom of a granular layer. Such a localized state of fluidization is relevant for some industrial processes (spouted bed, maintenance of navigable waterways,…) and for several geological issues (kimberlite volcano conduits, fluid venting, oil recovery in sandy soil, More precisely, what is presented here is a comparison between experiments, carried out by direct visualization throughout the medium, and numerical simulations, based on DEM modelling of the grains coupled to resolution of NS equations in the liquid phase (LBM). There is a very good agreement between the experimental phenomenology and the simulation results. When the flow-rate is increased, three regimes are successively observed: static bed, fluidized cavity that does not extend to the top of the layer, and finally fluidization over the entire height of layer that creates a fluidized chimney. A very strong hysteretic effect is present here with an extended range of stability for fluidized cavities when flow-rate is decreased back. This can be interpreted in terms force chains and arches. The influences of grain diameter, layer height and injection width are studied and interpreted using a model previously developed by Zoueshtiagh [1]. Finally, growing rate of the fluidized zone and possible coupling between two distinct injection orifices are also discussed.

Philippe, P.; Ngoma, J.; Delenne, J.

2012-12-01

274

Channel Morphology Response to Selective Wood Removals in a Sand-Laden Wisconsin Trout Stream  

Microsoft Academic Search

Large sand bed loads in trout stream headwaters can limit salmonid spawning habitat and reproductive success. This phenomenon has been observed in many northern Wisconsin watersheds, where historic logging practices are the likely source of the sediment loading. Presently, sediment transport is limited by abundant woody debris, causing channels to aggrade and bury gravels. We evaluated the impacts of a

Joshua D. Dumke; Thomas R. Hrabik; Valerie J. Brady; Karen B. Gran; Ronald R. Regal; Michael J. Seider

2010-01-01

275

Bed material agglomeration during fluidized bed combustion  

SciTech Connect

The purpose of this project is to determine the physical and chemical reactions which led to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. Survey of industrial-scale fluidized bed combustors is being conducted to determine the occurrence of bed agglomeration and the circumstances under which agglomeration took place. This task should be finished by the end of February. Samples of bed material, agglomerate material, and boiler deposits are being requested from boiler operators as part of the survey. Once received, these sample will be analyzed to determine chemical and mineralogic composition. The bulk chemical determination will be performed using x-ray fluorescence and inductively coupled plasma-optical emission (ICP). Mineralogy will be detected by x-ray diffraction (XRD). Chemical and mineral reactions will be determined by scanning electron microscopy, optical microscopy, and electron microprobe.

Brown, R.C.; Dawson, M.R.; Noble, S.

1993-02-01

276

Enuresis (Bed-Wetting)  

MedlinePLUS

... their development. Bed-wetting is more common among boys than girls. What causes bed-wetting? A number of things ... valves in boys or in the ureter in girls or boys Abnormalities in the spinal cord A small bladder ...

277

Response of phlebotomine sand flies to light-emitting diode-modified light traps in southern Egypt.  

PubMed

Centers For Disease Control and Prevention (CDC) light traps were modified for use with light-emitting diodes (LED) and compared against a control trap (incandescent light) to determine the effectiveness of blue, green, and red lights against standard incandescent light routinely used for sand fly surveillance. Light traps were baited with dry ice and rotated through a 4 x 4 Latin square design during May, June, and July, 2006. Trapping over 12 trap nights yielded a total of 2,298 sand flies in the village of Bahrif, 6 km north of Aswan on the east bank of the Nile River in southern Egypt. Phlebotomus papatasi comprised 94.4% of trap collections with five other species collected in small numbers. Over half (55.13%) of all sand flies were collected from red light traps and significantly more sand flies (P < 0.05) were collected from red light traps than from blue, green, or incandescent light traps. Red light traps collected more than twice as many sand flies as control (incandescent) traps and > 4 x more than blue and green light traps. Results indicate that LED red light is a more effective substitute for standard incandescent light when surveying in areas where P. papatasi is the predominant sand fly species. Each LED uses approximately 15% of the energy that a standard CDC lamp consumes, extending battery life and effective operating time of traps. Our prototype LED-modified traps performed well in this hot, arid environment with no trap failures. PMID:18260521

Hoel, D F; Butler, J F; Fawaz, E Y; Watany, N; El-Hossary, S S; Villinski, J

2007-12-01

278

Sand pictures : what's missing?  

NSDL National Science Digital Library

This activity opens with pictures of traditional African sand paintings called sonas. A sona is comprised of dots and loops. One design is missing, and students are asked to study the patterns and determine the appearance of the missing design. The activity, part of the Figure This! collection of 80 math challenges emphasizing real world math, explains the importance of mathematical patterns in archaeology and cultural anthropology. The Hint suggests that students examine the number and arrangement of dots and their relationship to the loops and squares in the designs. Multiple ways to analyze the pattern are given in the solution. Related questions ask students to develop a mathematical formula to express a pattern of dots and to draw lines to connect dots in an array. Answers to all questions and additional resources are provided. Copyright 2005 Eisenhower National Clearinghouse

National Council of Teachers of Mathematics (NCTM)

2002-01-01

279

Aging of Athabasca oil sand  

SciTech Connect

Samples of Athabasca oil sand collected by mining are frequently stored for long periods to ensure that research projects have available oil sand of consistent properties. This strategy is not entirely satisfactory because oil sands age after even limited exposure to oxygen. The results of a three-year aging study carried out at the Alberta Research Council are presented in this paper. During aging, the level of water soluble salts in the oil sand increased and hot water processing characteristics deteriorated. Through the DLVO and Ionizable Surface Group theories, it is demonstrated that the increase in soluble salts was sufficient to cause the fine solids particles to coagulate in the conditioning stage of the hot water process which results in poorer processibility characteristics. Based on this scenario, relative rates of aging for different grades of oil sand are estimated.

Wallace, D.; Henry, D.; Takamura, K.

1988-06-01

280

Sand and Water  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 7 November 2003

This image shows a relatively small crater (35 km across) in the heavily cratered terrain of the southern highlands. At the midlatitudes, this area is known both for its water-formed gullies and its sand dunes. This crater shows spectacular examples of both. In fact, the gullies running down the northern edge of the crater made it to the cover of Science magazine on June 30, 2000. The large dark spot in the floor of the crater is sand that has accumulated into one large dune with a single curvilinear crest.

Image information: VIS instrument. Latitude -54.9, Longitude 17.5 East (342.5 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2003-01-01

281

Bathing a patient in bed  

MedlinePLUS

Bed bath; Sponge bath ... bed to bathe. For these patients, daily bed baths can help keep their skin healthy, control odor, ... patient causes pain, plan to give the bed bath after the patient has received pain medicine and ...

282

Fluidized bed combustion process  

Microsoft Academic Search

This patent describes an FCC catalyst regeneration process for regenerating coke and nitrogen containing catalyst in an FCC regenerator with a regeneration gas comprising oxygen to form hot regenerated catalyst and flue gas. It comprises adding the spent FCC catalyst to a dense bed regeneration zone, operating at dense bed regeneration zone, operating at dense bed catalyst regeneration conditions including

G. J. Green; T. Y. Yan

1992-01-01

283

Making a Bed  

ERIC Educational Resources Information Center

The origins of this paper lay in making beds by putting pieces of plywood on a frame: If beds need to be 4 feet 6 inches by 6 feet 3 inches, and plywood comes in 4-foot by 8-foot sheets, how should one cut the plywood to minimize waste (and have stable beds)? The problem is of course generalized.

Wexler, Anthony; Stein, Sherman

2005-01-01

284

Bed material agglomeration during fluidized bed combustion. Technical progress report, 1 July, 1993--30 September, 1993  

SciTech Connect

Agglomerates formed in laboratory coal combustion tests were analyzed to determine the chemical and mineral reactions which lead to the cohesion of bed particles. Combustion tests were conducted at 75, 90, 100, and 120% theoretical air values. The test at 75% theoretical air resulted in the formation of bed agglomerates within 30 minutes. Agglomerates which formed at the lower theoretical air values were compared to unagglomerated bed samples by X-ray diffraction analyses. Polished thin sections of the agglomerates were made for optical and scanning electron microscopy. The results of these analyses indicate there were, in a broad sense, two types of mineralogic reactions which lead to the cohesion of bed particles in the agglomerates. One mechanism of cohesion resulted from the melting of bed particles to form a viscous material which bridged other bed particles. Based on the chemical composition of the glass (which resulted from the melt), this material was probably derived from aluminosilicate minerals in the sand bed or from clays within the coal. Because of the high iron content in these glasses (4 to 5 wt%), it is likely that iron pyrites in the coal were involved in fluxing reactions. In addition, MgO appears to be relatively high in the glasses. It is suspected that Ca-Mg carbonates (dolomite) from the bed sand are also involved in mineralogic reactions with the aluminosilicate melt. The second type of mineralogic reaction appears to be a reaction involving calcium and magnesium with other bed particles and with the aluminosilicate melt to form new mineral phases. Although the composition of these phases is somewhat variable, some resemble single-chain silicates or pyroxenes.

Brown, R.C.; Dawson, M.R.; Noble, S.D.

1993-11-01

285

2D DEM model of sand transport with wind interaction  

NASA Astrophysics Data System (ADS)

The advance of the dunes in the desert is a threat to the life of the local people. The dunes invade houses, agricultural land and perturb the circulation on the roads. It is therefore very important to understand the mechanism of sand transport in order to fight against desertification. Saltation in which sand grains are propelled by the wind along the surface in short hops, is the primary mode of blown sand movement [1]. The saltating grains are very energetic and when impact a sand surface, they rebound and consequently eject other particles from the sand bed. The ejected grains, called reptating grains, contribute to the augmentation of the sand flux. Some of them can be promoted to the saltation motion. We use a mechanical model based on the Discrete Element Method to study successive collisions of incident energetic beads with granular packing in the context of Aeolian saltation transport. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyze the features of the consecutive collision processes made by the transport of the saltating disks by a wind in which its profile is obtained from the counter-interaction between air flow and grain flows. We used a molecular dynamics method known as DEM (soft Discrete Element Method) with a initial static packing of 20000 2D particles. The dilation of the upper surface due to the consecutive collisions is responsible for maintaining the flow at a given energy input due to the wind.

Oger, L.; Valance, A.

2013-06-01

286

Effects of bed roughness on boundary layer mixing and mass flux across the sediment-water interface  

Microsoft Academic Search

Fine-scale measurements of boundary layer flow and solute transport were conducted within a laboratory flume to determine how bed topography influences mixing and mass transport at the sediment-water interface. Three different bed topographies were examined, with roughness composed of sand, gravel, or cobbles. Fluorescein dye, used as a dissolved tracer, was injected into the flow, and concentration and velocity were

M. A. Reidenbach; M. Limm; M. Hondzo; M. T. Stacey

2010-01-01

287

Sedimentology and stratigraphy of tidal sand ridges southwest Florida inner shelf  

SciTech Connect

Detailed investigation of linear shelf sand ridges located off the southwest coast of Florida shows them to be tide-dominated sand bodies. These ridges are remarkably similar to the large sand ridges of the North Sea, and they have abundant apparent analogs in the stratigraphic record, many of which are important petroleum producers. The Florida ridges are asymmetric in profile, about 10 km long, 1 km wide, with relief of 3-4 m with the adjacent sea bed. Extensive tidal current monitoring, sediment distribution patterns and side scan sonar surveys permit characterizing their morphodynamics. Tidal currents show distinct bidirectional patterns with speeds up to 70 cm/s. There is slight flood-dominance, and currents show much higher velocities in the troughs as compared to the crests of the ridges. Megaripples and sand waves are widespread and migrate obliquely across the ridges at opposite directions on the gentle and steep side of the ridge. Shallow, high-resolution seismic data and 39 vibracores din the area of the ridges show a consistent sequence characterized by three ascending Holocene lithofacies: (1) muddy quartz sand with limestone clasts; (2) bioturbated muddy shelly quartz sand; and (3) well-sorted, cross-stratified quartz sand that characterizes the sand ridges themselves. Each of the tidal sand ridges displays a coarsening-upward sequence of fine, well-sorted sand. Small-scale, multidirectional, cross stratification dominates the stratigraphy of the cores in this facies, but megaripple cross stratification is also present. All data indicate that these tidal ridges are good modern analogs for many of the shelf sand bodies in the ancient record, especially the Mesozoic of the mid-continent area.

Davis, R.A. Jr.; Klay, J.; Jewell, P. (Univ. of South Florida, Tampa (United States))

1993-01-01

288

Biosorption of Direct Red 28 (Congo Red) From Aqueous Solutions by Eggshells: Batch and Column Studies  

Microsoft Academic Search

The feasibility of using eggshells as a low-cost biosorbent for the removal of Direct Red 28 (DR 28) from aqueous solutions was studied in batch and dynamic flow modes of operation. Effect of biosorption process variables such as particle size, solution pH, initial dye concentration, contact time, temperature, feed flow rate and bed height were investigated. Both Langmuir and Freundlich

Papita Das Saha; Shamik Chowdhury; Madhurima Mondal; Keka Sinha

2011-01-01

289

Biosorption of Direct Red 28 (Congo Red) from Aqueous Solutions by Eggshells: Batch and Column Studies  

Microsoft Academic Search

The feasibility of using eggshells as a low-cost biosorbent for the removal of Direct Red 28 (DR 28) from aqueous solutions was studied in batch and dynamic flow modes of operation. The effect of biosorption process variables such as particle size, solution pH, initial dye concentration, contact time, temperature, feed flow rate, and bed height were investigated. Both the Langmuir

Papita Das Saha; Shamik Chowdhury; Madhurima Mondal; Keka Sinha

2012-01-01

290

Facies and architecture of deep-water Sandstone lobes: Comparison of a shale-rich and a sand-rich system  

SciTech Connect

Two different foreland-basin deep-water sandstone systems have been studied for reservoir characterization purposes: the Broto lobes of the Eocene Hecho group, spain, and two sand bodies of the Oligocene-Miocene Arakintos Sandstone, Greece. The shale-rich Broto lobes are characterized by distinct vertical developments in terms of facies and expression of heterogeneity. Bed-thickness trends, lateral extent of sand beds, and facies variability are related to overall sand/shale ratio. A feature common to most of the sandstone packages is the occurrence of a basal slump and/or pebbly mudstone. The dominant sediment source is considered fluvial. Variation in sand quality within and between lobes is high. Deposition is considered to be strongly controlled by tectonics. The sand-rich Arakintos Sandstone consists of massive and pebbly sandstones, forming thick, sandy sheets alternating with relatively coarse-grained, thin-bedded turbidites. Facies, geometries, vertical organization, and the relation between grain size and bed thickness indicate a constrained development of the lobes, partly influenced by preexisting topography. A coastal sediment source is inferred. Little variation exists in sand quality within and between the lobes. The overall regularity in terms of facies, and the absence of slumps, suggest that fluctuations in relative sea level may have formed a major control on deposition. The two lobe systems illustrate the effect of tectonics, sediment type, topographic confinement, and possible sea level on facies and sand body architecture of deep-water sandstone lobes.

Schuppers, J.D. (Delft Univ. of Technology (Netherlands))

1993-09-01

291

Ferrous sulphate oxidation using Thiobacillus ferrooxidans cells immobilised on sand for the purpose of treating acid mine-drainage  

Microsoft Academic Search

Thiobacillus ferrooxidans was immobilised on sand (size 0.85 mm to 1.18 mm) for use in a repeated batch and continuously operated packed-bed bioreactor which has not been previously reported in the literature. Repeated batch operation resulted in the complete oxidation of ferrous to ferric iron. The bacteria were active immediately after 3-4 weeks in a non-aqueous medium; i.e. the sand

T. A. Wood; K. R. Murray; J. G. Burgess

2001-01-01

292

Wind tunnel observation on the effect of a porous wind fence on shelter of saltating sand particles  

Microsoft Academic Search

A porous wind fence is an artificial barrier widely employed to abate wind erosion. This study investigated the shelter effect of a porous wind fence on saltating sand in a simulated atmospheric boundary layer (ABL). A wind fence with a porosity ?=38.5% was installed on a flat bed of sand collected from a beach (diameter, d=200–300?m). A high-speed digital camera

Ning Zhang; Jong-Hoon Kang; Sang-Joon Lee

2010-01-01

293

Bed material transport in the Virgin River, Utah  

USGS Publications Warehouse

Detailed information concerning the rate and particle size distribution of bed material transport by streamflows can be very difficult and expensive to obtain, especially where peak streamflows are brief and bed material is poorly sorted, including some very large boulders. Such streams, however, are common in steep, arid watersheds. Any computational approach must consider that (1) only the smaller particle sizes present on the streambed move even during large floods and (2) the largest bed particles exert a significant form drag on the flow. Conventional methods that rely on a single particle size to estimate the skin friction shear stress acting on the mobile fraction of the bed material perform poorly. Instead, for this study, the skin friction shear stress was calculated for the observed range of streamflows by calculating the form drag exerted on the reach-averaged flow field by all particle sizes. Suspended and bed load transported rates computed from reach-averaged skin friction shear stress are in excellent agreement with measured transport rates. The computed mean annual bed material load, including both bed load and suspended load, of the East Fork Virgin River for the water years 1992-1996 was approximately 1.3 x 105 t. A large portion of the bed material load consists of sand-sized particles, 0.062-1.0 mm in diameter, that are transported in suspension. Such particles, however, constituted only 10% of the surface bed material and less than 25% of the subsurface bed material. The mean annual quantity of bed load transported was 1060 t/yr with a median size of 15 mm.

Andrews, E. D.

2000-01-01

294

Heat transfer to horizontal tubes in a pilot-scale fluidized-bed combustor burning low-rank coals  

Microsoft Academic Search

Experimental data are obtained for the heat transfer coefficient between immersed horizontal tube bundles and an atmospheric-fluidized-bed combustor burning low-rank coals. Silica sand (d\\/sub p\\/ = 888 to 1484 ..mu..m) and limestone (d\\/sub p\\/ = 716 to 1895 ..mu..m) are used as bed material. The tests are conducted, with and without limestone addition and ash recycle, at average bed temperatures

N. S. Grewal; G. Goblirsch

1983-01-01

295

Heat transfer to horizontal tubes in a pilot-scale fluidized-bed combustor burning low-rank coals  

Microsoft Academic Search

Experimental data are obtained for the heat transfer coefficient between immersed horizontal tube bundles and an atmospheric-fluidized-bed combustor burning low-rank coals. Silica sand and limestone are used as bed material. The tests are conducted, with and without limestone addition and ash recycle, at average bed temperatures ranging from 1047 to 1125 K, superficial fluidizing velocity of 1.66 to 2.04 m\\/s,

N. S. Grewal; G. Goblirsch

1983-01-01

296

HEAT TRANSFER TO HORIZONTAL TUBES IN A PILOT-SCALE FLUIDIZED-BED COMBUSTOR BURNING LOW-RANK COALS  

Microsoft Academic Search

Experimental data are obtained for the heat transfer coefficient between immersed horiziontal tube bundles and an atmospheric-fluidized-bed combustor burning low-rank coals. Silica sand (dp = 888 to 1484 ?m) and limestone (dp 7= 716 to 1895 ?m) are used as bed material. The tests are conducted, with and without limestone addition and ash recycle, at average bed temperatures ranging from 1047 to

N. S. GREWAL; E. S. SORENSON; G. GOBLIRSCH

1985-01-01

297

Finding Red  

NSDL National Science Digital Library

In this chemistry challenge, learners systematically investigate which combination of four solutions produces a deep red color. The four solutions are iron(III) chloride, ammonium thiocyanate, tannic acid, and oxalic acid. Background information explains that it is the iron ions in solution combining with ions from the other solutions to create the different colors. After learners discover the different colors, they are encouraged to add a third solution to see if the color can be changed, an example of how chemical equilibrium can be shifted. This activity may take a bit more time with younger learners. For safety reasons, adult supervision is recommended and can be conducted as a demonstration for younger audiences.

Sciencenter

2012-07-12

298

Studies of Phlebotomine Sand Flies.  

National Technical Information Service (NTIS)

Psychodid sand flies in the subfamily Phlebotominae are medically important, hematophagus insects which are widely distributed and often abundant in the tropics. About 550 species in six genera are known with over half occurring in the New World. The lite...

D. G. Young G. B. Fairchild

1973-01-01

299

Spherical Waves in Saturated Sand.  

National Technical Information Service (NTIS)

The Naval Surface Warfare Center needs to develop the capability to determine numerically the characteristics of a propagating stress wave in saturated sand. To provide needed experimental data, SRI International performed precision experiments with the o...

P. R. Gefken A. L. Florence M. Sanai

1996-01-01

300

Sand Reclamation Concept Definition Study.  

National Technical Information Service (NTIS)

Foundry sand reclamation methods, including wet, dry, thermal and combination processes, were reviewed to identify the state-of-the-art and needed research. The major features of the various systems are summarized. Trends were determined from input from s...

M. Granlund

1990-01-01

301

Numerical simulation of bed morphodynamics in natural waterways: From ripples to dunes  

NASA Astrophysics Data System (ADS)

We develop and validate a 3D numerical model for coupled simulations of turbulence and sand-bed morphodynamics in natural waterways under live bed conditions. We employ the Fluid-Structure Interaction Curvilinear Immersed Boundary (FSI-CURVIB) method of Khosronejad et al. (Adv. in Water Res., 2011). The mobile channel bed is discretized with an unstructured triangular grid and treated as the sharp-interface immersed boundary embedded in a background curvilinear mesh. Transport of bed load and suspended load sediments are combined in the non-equilibrium form of the Exner-Poyla for the bed surface elevation, which evolves due to the spatio-temporally varying bed shear stress and velocity vector induced by the turbulent flow field. Both unsteady RANS and large-eddy simulation (LES) models are implemented to simulate the effects of turbulence. Simulations are carried out for a wide range of waterways, from small scale streams to large-scale rivers with and without embedded in stream structures, and the simulated sand-waves are quantitatively compared to available measurements. It is shown that the model can accurately capture sand-wave formation, growth, and migration processes observed in nature. The simulated bed-forms are found to have amplitude and wave length scales ranging from the order of centimeters up to several meters.

Sotiropoulos, F.; Khosronejad, A.

2012-12-01

302

Predicting fractional bed load transport rates: Application of the Wilcock-Crowe equations to a regulated gravel bed river  

USGS Publications Warehouse

Bed load samples from four locations in the Trinity River of northern California are analyzed to evaluate the performance of the Wilcock-Crowe bed load transport equations for predicting fractional bed load transport rates. Bed surface particles become smaller and the fraction of sand on the bed increases with distance downstream from Lewiston Dam. The dimensionless reference shear stress for the mean bed particle size (t*rm) is largest near the dam, but varies relatively little between the more downstream locations. The relation between t*rm and the reference shear stresses for other size fractions is constant across all locations. Total bed load transport rates predicted with the Wilcock-Crowe equations are within a factor of 2 of sampled transport rates for 68% of all samples. The Wilcock-Crowe equations nonetheless consistently under-predict the transport of particles larger than 128 mm, frequently by more than an order of magnitude. Accurate prediction of the transport rates of the largest particles is important for models in which the evolution of the surface grain size distribution determines subsequent bed load transport rates. Values of term estimated from bed load samples are up to 50% larger than those predicted with the Wilcock-Crowe equations, and sampled bed load transport approximates equal mobility across a wider range of grain sizes than is implied by the equations. Modifications to theWilcock-Crowe equation for determining t*rm and the hiding function used to scale term to other grain size fractions are proposed to achieve the best fit to observed bed load transport in the Trinity River. Copyright 2009 by the American eophysical Union.

Gaeuman, D.; Andrews, E. D.; Kraus, A.; Smith, W.

2009-01-01

303

Near-shore sand thickness and stratigraphy mapping with a submerged GPR antenna system; southeast Lake Michigan  

SciTech Connect

Twenty-one shore perpendicular profiles, spaced at nominal 5 km intervals, have been surveyed with a bottom-sled mounted Ground Penetrating Radar (GPR) antenna system between Benton Harbor, MI, and Gary, IN. Either a commercial 500 MHz or a custom 145 MHz antenna were used. The bottom sled also carried an upward looking SONAR transducer to give concurrent water depth, and was towed from the beach out to water depths of 6 meters or more, usually ending about 500 meters from shore. Bedding structures and details are clearly visible on the GPR sections within the sand bars and sand blankets. Bottom morphology and the nature of the sand bodies change markedly from the NE to the SW limits of the survey area. At the NE profiles there are multiple, pronounced (or high amplitude) offshore bars, with the substrate (glacial clay, shale, or silty sand) exposed or nearly exposed between bars. Internal structure is generally foreset or cross bedding in the bars. Sand was thin or missing immediately to the Sw of several other jetty structures in addition to the one at St. Joseph. In general the sand bars became much less pronounced to the SW, and internal structures were dominated by parallel bedding and subtle angular unconformities. Near St. Joseph, the exposed substrate is almost certainly being eroded, even to water depths as great as 6 meters. Thus, the equilibrium bottom profile continues to deepen shoreward, causing the continued threat of bluff erosion in spite of annual beach nourishment efforts at this site.

Sauck, W.A.; Seng, D.L. (Western Michigan Univ., Kalamazoo, MI (United States))

1994-04-01

304

Modelling of saturated sand flux  

NASA Astrophysics Data System (ADS)

We derive a saturated sand flux model based on the previous models of Sauermann et al (2001 Phys. Rev. E 64 0313005) and Sørensen (2004 Geomorphology 59 53) and determine its parameters, as a function of the grain and fluid properties, from a comparison with wind tunnel data. We also show that dunes simulated with the new sand transport model compare well with observations of Moroccan dunes.

Durán, O.; Herrmann, H.

2006-07-01

305

Pressure Fluctuations as a Disgnostic Tool for Fluidized Beds.  

SciTech Connect

The validity of using bubbling fluidized bed (BFB) similitude parameters to match a hot BFB to a cold BFB is being studied. Sand in a BFB combustor and copper powder in cold BFB model have been analyzed and found to be out of similitude. In the analysis process, it was determined that the condition of the screen covering the pressure tap affects the quality of pressure data recorded. In addition, distributor plate design and condition will affect the hydrodynamics of the bed. Additional tests are planned to evaluate the validity of similitude concepts in BFB.

Brown, R.C.; Schroeder, J.R.

1997-10-28

306

Tar sands. (FL74-56)  

Microsoft Academic Search

In terms of in-place deposits, tar sands are a relatively small hydrocarbon resource. Though ''small'' by comparison with coal and shale, tar sands have been commercially processed since 1968, and a second plant is now under construction. Many processes have been proposed to extract the bitumen from tar sands. These include both in-situ methods, and processing of mined tar sands.

1974-01-01

307

Alberta's oil sands in-situ pilots  

SciTech Connect

A brief description is given of the Alberta Oil Sands deposits and the current active pilots which are testing various recovery processes. The role of the Alberta Oil Sands Technology and Research Authority (AOSTRA) in these oil sands pilots is discussed, and details of six AOSTRA funded pilots in the major oil sands and heavy oil areas of Alberta are presented.

Phillips, R.S.

1981-01-01

308

Behavior of cemented sands - I. Testing  

Microsoft Academic Search

This paper is accompanied by a study on constitutive modelling issues of cemented sands. The concentration here is on experimental issues related to the triaxial testing of cemented sands. A preliminary investigation is performed aiming to identify potential effects of specimen size and slenderness on the stress-strain-strength characteristics of cemented sands. A comprehensive experimental study follows where clean sand specimens,

Ali A. Abdulla; Panos D. Kiousis

1997-01-01

309

Fluidized bed combustion  

SciTech Connect

This patent describes a vessel. It comprises a fluid bed for continuously incinerating fuel comprising tire segments and the like which comprise metallic wire tramp and for concurrently removing tramp and bed materials at a bottom effluent exit means of the vessel, the vessel further comprising static air distributor means at the periphery of the bed comprising a substantially centrally unobstructed relatively large central region in which the fluid bed and fuel only are disposed and through which bed material and tramp migrate without obstruction to and through the effluent exit means, downwardly and inwardly stepped lower vessel wall means and a plurality of peripherally located centrally directed vertically and horizontally offset spaced air influent means surrounding the central region and associated with the stepped lower vessel wall means by which the bed is supported and fluidized.

Sowards, N.K.; Murphy, M.L.

1991-10-29

310

Fluidized bed combustor modeling  

NASA Technical Reports Server (NTRS)

A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

1977-01-01

311

Seeing Red  

NASA Technical Reports Server (NTRS)

This New Horizons image of Jupiter's volcanic moon Io was taken at 13:05 Universal Time during the spacecraft's Jupiter flyby on February 28, 2007. It shows the reddish color of the deposits from the giant volcanic eruption at the volcano Tvashtar, near the top of the sunlit crescent, as well as the bluish plume itself and the orange glow of the hot lava at its source. The relatively unprocessed image on the left provides the best view of the volcanic glow and the plume deposits, while the version on the right has been brightened to show the much fainter plume, and the Jupiter-lit night side of Io.

New Horizons' color imaging of Io's sunlit side was generally overexposed because the spacecraft's color camera, the super-sensitive Multispectral Visible Imaging Camera (MVIC), was designed for the much dimmer illumination at Pluto. However, two of MVIC's four color filters, the blue and 'methane' filter (a special filter designed to map methane frost on the surface of Pluto at an infrared wavelength of 0.89 microns), are less sensitive than the others, and thus obtained some well-exposed views of the surface when illumination conditions were favorable. Because only two color filters are used, rather than the usual three, and because one filter uses infrared light, the color is only a rough approximation to what the human eye would see.

The red color of the Tvashtar plume fallout is typical of Io's largest volcanic plumes, including the previous eruption of Tvashtar seen by the Galileo and Cassini spacecraft in 2000, and the long-lived Pele plume on the opposite side of Io. The color likely results from the creation of reddish three-atom and four-atom sulfur molecules (S3 and S4) from plume gases rich in two-atom sulfur molecules (S2 After a few months or years, the S3 and S4 molecules recombine into the more stable and familiar yellowish form of sulfur consisting of eight-atom molecules (S8), so these red deposits are only seen around recently-active Io volcanos. Though the plume deposits are red, the plume itself is blue, because it is composed of very tiny particles that preferentially scatter blue light, like smoke. Also faintly visible in the left image is the pale-colored Prometheus plume, almost on the edge of the disk on the equator at the 9 o'clock position.

Io was 2.4 million kilometers from the spacecraft when the picture was taken, and the center of Io's disk is at 77 degrees West longitude, 5 degrees South latitude. The solar phase angle was 107 degrees.

2008-01-01

312

Heterogeneous catalytic ozonation of benzothiazole aqueous solution promoted by volcanic sand.  

PubMed

This paper presents experimental results on the catalytic effect of volcanic sand on benzothiazole ozonation. Experiments were assessed at laboratory scale, in a differential circular flow reactor composed of a volcanic sand fixed bed column of 19 cm3 and a 1 dm3 storage tank, operated in batch mode at 20 degrees C and pH 2-7. Experimental results show that ozone self-decomposition is enhanced by the presence of volcanic sand at all pH. At pH>pH(PZC), the increase in aqueous ozone decay could be related to ozone interaction with strong Lewis acid on metal oxide surface sites of the volcanic sand. Ozone self-decomposition reactions occurring on the volcanic sand are less affected by the presence of radical scavengers. Benzothiazole removal by ozonation is also enhanced by the presence of volcanic sand. Moreover, the inhibitory effect of free radical scavengers is also impaired by volcanic sand, suggesting that strong Lewis acid surface sites play a key role on the reaction mechanism. PMID:18029089

Valdés, H; Murillo, F A; Manoli, J A; Zaror, C A

2008-05-30

313

Analysis of atmospheric fluidized bed combustion agglomerates. Final report  

SciTech Connect

Chemical and textural studies of AFBC agglomerates have revealed detailed information regarding the mechanisms of agglomeration. The formation of agglomerates in a silica sand bed can be described by a four step process: initial ash coatings of quartz grains; thickening of ash coatings and the formation of nodules; cementation of nodules to each other by a sulfated aluminosilicate matrix; and partial or complete melting of eutectic compositions to produce a sticky glass phase between grains and along fractures. Once agglomeration has begun, large scale solidification and restricted flow within the bed will lead to hot spots, wholesale melting and further agglomeration which ultimately forces a shutdown. Standard operating temperatures during normal AFBC runs come quite close to, or may actually exceed, the minimum temperatures for eutectic melting of the silicate phases in the coal and standard bed materials. The partially melted material may be expected to lead to the formation of dense, sticky areas within the bed, and the formation of hot spots which further exacerbate the problem. Ultimately, large scale bed agglomeration will result. Attempts to eliminate agglomeration by removal of sodium via an ion exchange process have yielded encouraging results. A second approach, used to raise melting temperatures within the bed, has been to use bed materials that may react with low-temperature minerals to produce high-temperature refractory phases such as mullite or other alkali and alkali-earth alumino-silicates.

Perkins, D. III; Brekke, D.W.; Karner, F.R.

1984-04-01

314

Colorimetric analysis of water and sand samples performed on a mobile phone  

Microsoft Academic Search

Analysis of water and sand samples was done by reflectance measurements using a mobile phone. The phone's screen served as light source and front view camera as detector. Reflected intensities for white, red, green and blue colors were used to do principal component analysis for classification of several compounds and their concentrations in water. Analyses of colored solutions and colorimetric

Zafar Iqbal; Robert B. Bjorklund

2011-01-01

315

Combustion of polymer pellets in a bubbling fluidised bed  

Microsoft Academic Search

Single pellets (?3mm diameter) of high density polyethylene (HDPE) have been burned in an electrically heated bed of silica sand, fluidised by air or mixtures of N2 and O2 at atmospheric pressure. During the combustion of single pellets, measurements were made of the concentrations of CO and CO2 in the off-gas, enabling burnout-times to be derived. This was done for

F. Burgess; P. D. W. Lloyd; P. S. Fennell; A. N. Hayhurst

2011-01-01

316

Controls on the composition of fluvial sands from a tropical weathering environment: sands of the Orinoco River drainage basin, Venezuela and Colombia  

USGS Publications Warehouse

On the alluvial plains of the western Llanos, storage of orogenically derived sediment allows time for substantial chemical weathering. Through reworking of the alluvial sequences, freshly eroded sediment is exchanged for older, compositionally more mature material. The chemically weathered component increases as rivers cross the Llanos, resulting in an increase in overall compositional maturity of bed-load sand away from the orogenic terranes. -from Authors

Johnsson, M. J.; Stallard, R. F.; Lundberg, N.

1991-01-01

317

Replicating the microbial community and water quality performance of full-scale slow sand filters in laboratory-scale filters.  

PubMed

Previous laboratory-scale studies to characterise the functional microbial ecology of slow sand filters have suffered from methodological limitations that could compromise their relevance to full-scale systems. Therefore, to ascertain if laboratory-scale slow sand filters (L-SSFs) can replicate the microbial community and water quality production of industrially operated full-scale slow sand filters (I-SSFs), eight cylindrical L-SSFs were constructed and were used to treat water from the same source as the I-SSFs. Half of the L-SSFs sand beds were composed of sterilized sand (sterile) from the industrial filters and the other half with sand taken directly from the same industrial filter (non-sterile). All filters were operated for 10 weeks, with the microbial community and water quality parameters sampled and analysed weekly. To characterize the microbial community phyla-specific qPCR assays and 454 pyrosequencing of the 16S rRNA gene were used in conjunction with an array of statistical techniques. The results demonstrate that it is possible to mimic both the water quality production and the structure of the microbial community of full-scale filters in the laboratory - at all levels of taxonomic classification except OTU - thus allowing comparison of LSSF experiments with full-scale units. Further, it was found that the sand type composing the filter bed (non-sterile or sterile), the water quality produced, the age of the filters and the depth of sand samples were all significant factors in explaining observed differences in the structure of the microbial consortia. This study is the first to the authors' knowledge that demonstrates that scaled-down slow sand filters can accurately reproduce the water quality and microbial consortia of full-scale slow sand filters. PMID:24908577

Haig, Sarah-Jane; Quince, Christopher; Davies, Robert L; Dorea, Caetano C; Collins, Gavin

2014-09-15

318

Phosphorus retention capacity of root bed media of sub-surface flow constructed wetlands  

Microsoft Academic Search

Phosphorus retention by sub-surface flow constructed wetlands is dependent upon the effluent quality, loading rate and type of root bed media. Three types of root bed media (Lockport dolomite, Queenston shale and Fonthill sand) at various stages of their use were sampled from a sub-surface flow wetland located in Sewage Waste Amendment Marsh Process Project (SWAMP), Niagara-on-the-Lake, Ontario, Canada, and

H. K Pant; K. R Reddy; E Lemon

2001-01-01

319

The effects of removing bed materials on flow velocity (case study: Zaremrood River, Iran)  

Microsoft Academic Search

Nowadays, in parts of Iran, rivers and flood plains are being used as sand and silt mines, and the removal of river bed materials\\u000a is performed without studying its effects on hydraulic behavior. On the other hand, the flood plain lands are in danger of\\u000a floods and bank erosion. Zaremrood River in Tajan watershed due to removal of river bed

K. Solaimani; M. Habibnejad; A. Hamidi

320

Sand Density as Sandpile Descriptor  

NASA Astrophysics Data System (ADS)

We investigate a collection of one-parametric families of isotropic sandpile models. The models involve the square lattice slowly accumulating the grains and quickly transferring them as the local piles become over-critical. The paper groups the sand-piles with respect to two features influencing the model dynamics. They are the value of the local transfer's stochasticity and the number of the transferred grains. Every pair generates one-parametric family of the sand-piles. The parameter reflects the relative height of an over-critical pile with respect to the incoming flow of sand. If the stochasticity disappears with the growth of the parameter, the families with the fixed number of the transferred grains have much in common with Bak et al.'s sand-pile [Phys. Rev. Lett. 59, 381 (1987)], while the families, whose over-critical piles lose all their grains, tend to the Zhang sand-pile [Phys. Rev. Lett. 63, 470 (1989)]. The families with non-disappearing variance give rise to new properties described in terms of the probability distribution of the pile heights.

Shapoval, A. B.; Shnirman, M. G.

321

Sand Dunes in Noachis Terra  

NASA Technical Reports Server (NTRS)

11 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark-toned sand dunes in a crater in eastern Noachis Terra. Most big martian dunes tend to be dark, as opposed to the more familiar light-toned dunes of Earth. This difference is a product of the composition of the dunes; on Earth, most dunes contain abundant quartz. Quartz is usually clear (transparent), though quartz sand grains that have been kicked around by wind usually develop a white, frosty surface. On Mars, the sand is mostly made up of the darker minerals that comprise iron- and magnesium-rich volcanic rocks--i.e., like the black sand beaches found on volcanic islands like Hawaii. Examples of dark sand dunes on Earth are found in central Washington state and Iceland, among other places. This picture is located near 49.0oS, 326.3oW. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.

2004-01-01

322

Process and apparatus to produce crude oil from tar sands. Final report  

SciTech Connect

A two-staged fluidized-bed reactor for the energy-efficient, thermal recovery of bitumen from Utah tar sands has been constructed. This reactor is a scaled-up version of an earlier system investigated at the University of Utah, and involves the use of three liquid-potassium heat pipes which thermally couple an upper pyrolysis bed with a lower combustion bed. The reactor has been studied to determine the effect of multiple heat pipes, increased feed rate, and longer duration run times. The process consists essentially of three steps. In the first step, mined and suitably sized tar sand, being fed into the reactor at a constant rate, is pyrolyzed at temperatures of 440/sup 0/C to above 500/sup 0/C in an inert atmosphere to volatilize and partially crack most of the contained bitumen. The vaporized products of the pyrolysis section are condensed and coalesced to give a synthetic crude oil. In the second step, coked sand, formed as a by-product in the pyrolysis reactor, is combusted with air at temperatures between 550 and 600/sup 0/C. In the third step, heat is recovered from the hot spent sand leaving the combustion bed by a fluidized-bed heat exchanger using vertical copper cooling tubes. Over 30 runs, with tar sand from the Sunnyside, PR Springs, and Whiterocks deposits, have been made to study controllability of the process, heat requirements, and liquid product yield with respect to process variables such as pyrolysis-bed temperature and average solids-residence times. The highest liquid yield obtained was 71 weight percent of the original tar sand bitumen. Typically, coke yield is from 15 to 20 weight percent, with gas yield making up the difference. As a result of the study, recommendations have been developed for a design procedure suitable for scale-up to a 15,000 barrel/day production unit. Included are typical operating conditions and product properties. 31 references, 35 figures, 12 tables.

Seader, J.D.; Smart, L.M.

1984-07-01

323

Fluidized bed calciner apparatus  

DOEpatents

An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member. Disposed in the lower portion of the inner shell are a plurality of internal electric resistance heaters for heating the fluidized bed. Disposed circumferentially about the outside length of the inner shell are a plurality of external heaters for heating the inner shell thereby heating the fluidized bed. Further, connected to the internal and external heaters is a means for maintaining the fluidized bed temperature to within plus or minus approximately 25.degree. C. of a predetermined bed temperature. Disposed about the external heaters is the outer shell for providing radiative heat reflection back to the inner shell.

Owen, Thomas J. (West Richland, WA); Klem, Jr., Michael J. (Richland, WA); Cash, Robert J. (Richland, WA)

1988-01-01

324

Virus Transport through Solid Beds.  

National Technical Information Service (NTIS)

A theoretical model for predicting the breakthrough curve of viruses from solid beds is developed. This model includes the percolation of contaminated water through clean solid beds (saturation) and of uncontaminated water through contaminated beds (eluti...

S. Sundaram

1977-01-01

325

Windblown Sand in West Candor  

NASA Technical Reports Server (NTRS)

23 December 2003

West Candor Chasma, a part of the vast Valles Marineris trough system, is known for its layered sedimentary rock outcrops. It is less known for dark fields of windblown sand, but that is what occurs in the north-central part of the chasm. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, obtained in December 2003, shows the interplay of dark, wind-blown sand with buttes and mesas of layered rock in west Candor Chasma. Dark streamers of sand point toward the east/southeast (right/lower right), indicating that dominant winds blow from the west. This picture is located near 5.2oS, 75.7oW, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

2004-01-01

326

History of development and depositional environment and upper Cherokee Prue Sand, Custer and Roger Mills counties, Oklahoma  

SciTech Connect

In western Oklahoma the uppermost sand member of the Cherokee Group, the True sand, was first drilled and found productive in two discoveries, completed in 1980, in west-central Custer County and in central Roger Mills County, Oklahoma. For 1 1/2 to 2 years these two discoveries, some 18 mi (29 km) apart, were thought to be stratigraphic equivalents of two separate sand bodies occurring parallel to the classic northwest-southeast-trending systems of the Anadarko basin. At present, some 40 productive wells will ultimately produce more than 100 bcf of gas and 3 million bbl of condensate from an average depth of 11,500 ft (3500 m). Sand porosities range from 3 to 18% with most producing wells having porosities in the 12 to 15% range. Because Prue sand is slightly overpressured (a pressure gradient of .53 psi/foot), the reserves are generally better than normal-pressured wells at this depth. The sand body is over 40 mi (64 km) in length, 1 to 1.5 mi (1.6 to 2.4 km) wide, and 60 ft (18 m) thick. Study of the core shows the interval to grade from a medium to fine-grained sand, highly laminated and cross-bedded with black shale, to a slightly coarser grained nonstructured interval and back into a highly laminated cross-bedded sandy black shale interval. The interval is topped by a 10 ft (3 m) thick black shale layer that is a predominant bed throughout the whole area. These conclusions have implications that may assist in the exploration of other Pennsylvanian sands in this area.

Baumann, D.K.; Peterson, M.L.; Hunter, L.W.

1983-03-01

327

Sands at Gusev Crater, Mars  

NASA Astrophysics Data System (ADS)

environments, and the energy associated with the transport and deposition of sand at Gusev Crater are characterized at the microscopic scale through the comparison of statistical moments for particle size and shape distributions. Bivariate and factor analyses define distinct textural groups at 51 sites along the traverse completed by the Spirit rover as it crossed the plains and went into the Columbia Hills. Fine-to-medium sand is ubiquitous in ripples and wind drifts. Most distributions show excess fine material, consistent with a predominance of wind erosion over the last 3.8 billion years. Negative skewness at West Valley is explained by the removal of fine sand during active erosion, or alternatively, by excess accumulation of coarse sand from a local source. The coarse to very coarse sand particles of ripple armors in the basaltic plains have a unique combination of size and shape. Their distribution display significant changes in their statistical moments within the ~400 m that separate the Columbia Memorial Station from Bonneville Crater. Results are consistent with aeolian and/or impact deposition, while the elongated and rounded shape of the grains forming the ripples, as well as their direction of origin, could point to Ma'adim Vallis as a possible source. For smaller particles on the traverse, our findings confirm that aeolian processes have dominated over impact and other processes to produce sands with the observed size and shape patterns across a spectrum of geologic (e.g., ripples and plains soils) and aerographic settings (e.g., wind shadows).

Cabrol, Nathalie A.; Herkenhoff, Kenneth; Knoll, Andrew H.; Farmer, Jack; Arvidson, Raymond; Grin, Edmond; Li, Ronxing; Fenton, Lori; Cohen, Barbara; Bell, James F.; Aileen Yingst, R.

2014-05-01

328

Geology on a Sand Budget  

NSDL National Science Digital Library

Earth science teaches know how frustrating it can be to spend hundreds of dollars on three-dimensional (3-D) models of Earth's geologic features, only to use the models for a few class periods. To avoid emptying an already limited science budget, teachers can use a simple alternative to the expensive 3-D models--sand. Modeling geologic processes and features with sand is an effective way for teachers to promote student understanding of Earth science topics, quickly assess students' prior knowledge, and identify common misconceptions.

Kane, Jacqueline

2004-09-01

329

Tar sands and oil shales  

Microsoft Academic Search

The worlds largest potential liquid-hydrocarbon reserves are not recoverable by ordinary oil-producing methods. These reserves are the Athabasca tar sands of northern Alberta in Canada and the Green River oil shales of Colorado, Utah, and Wyoming. The two deposits differ in their chemistry, physical state, and history. Both contain hydrocarbons that can be converted economically into petroleum products. Both occur

de Never

1966-01-01

330

Geology on a Sand Budget  

ERIC Educational Resources Information Center

Earth science teachers know how frustrating it can be to spend hundreds of dollars on three-dimensional (3-D) models of Earth's geologic features, to use the models for only a few class periods. To avoid emptying an already limited science budget, the author states that teachers can use a simple alternative to the expensive 3-D models--sand. She…

Kane, Jacqueline

2004-01-01

331

Sand and Water Table Play  

ERIC Educational Resources Information Center

The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

Wallace, Ann H.; White, Mary J.; Stone, Ryan

2010-01-01

332

V-2 at White Sands  

NASA Technical Reports Server (NTRS)

A V-2 rocket is hoisted into a static test facility at White Sands, New Mexico. The German engineers and scientists who developed the V-2 came to the United States at the end of World War II and continued rocket testing under the direction of the U. S. Army, launching more than sixty V-2s.

1947-01-01

333

Studies of Phlebotomine Sand Flies.  

National Technical Information Service (NTIS)

Studies of phlebotomine sand flies from Guatemala showed that 13 out of 25 total species have not been previously reported from that country. A review of these species is given here. It includes illustrations and a description of a new species. Other new ...

D. G. Young

1981-01-01

334

Technology Assessment of Intermittent Sand Filters.  

National Technical Information Service (NTIS)

Intermittent sand filtration of wastewater is not a new technology. Sand filters were often used by sewered communities around the turn of the century. However, as wastewater flows and land costs increased, they were replaced by mechanical treatment proce...

D. L. Anderson R. L. Siegrist R. J. Otis

1985-01-01

335

Loose sand habitat at the Mojave desert  

NSDL National Science Digital Library

Loose sand soil lacks moisture but contains adequate moisture and nutrients for drought tolerant plants. Loose sand soil is insufficient for animals to find or make shelter. Organisms find shade and shelter under the large shrubs.

Katie Hale (California State University, Fullerton;Student. Biological Sciences)

2007-01-06

336

Sand Impact Tests of a Half-Scale Crew Module Boilerplate Test Article  

NASA Technical Reports Server (NTRS)

Although the Orion Multi-Purpose Crew Vehicle (MPCV) is being designed primarily for water landings, a further investigation of launch abort scenarios reveals the possibility of an onshore landing at Kennedy Space Center (KSC). To gather data for correlation against simulations of beach landing impacts, a series of sand impact tests were conducted at NASA Langley Research Center (LaRC). Both vertical drop tests and swing tests with combined vertical and horizontal velocity were performed onto beds of common construction-grade sand using a geometrically scaled crew module boilerplate test article. The tests were simulated using the explicit, nonlinear, transient dynamic finite element code LS-DYNA. The material models for the sand utilized in the simulations were based on tests of sand specimens. Although the LSDYNA models provided reasonable predictions for peak accelerations, they were not always able to track the response through the duration of the impact. Further improvements to the material model used for the sand were identified based on results from the sand specimen tests.

Vassilakos, Gregory J.; Hardy, Robin C.

2012-01-01

337

Sand injectites at the base of the Coconino Sandstone, Grand Canyon, Arizona (USA)  

NASA Astrophysics Data System (ADS)

In the Grand Canyon, large tabular and wedge shaped sand-filled cracks commonly occur at the base of the Coconino Sandstone, penetrating downward into the coarse siltstones of the Hermit Formation. All previous workers have casually identified the vertical sand-filled cracks as desiccation cracks. Until now, they have never been studied. Cracks and their associated features were found and examined at thirty locations; and it was found that they have characteristics difficult to explain using desiccation mud cracks or large playa cracks as a model. Instead, it was found the cracks have features commonly found in clastic dikes and sand injectites. Some lateral sand bodies associated with the cracks have clastic sill-like characteristics. Liquefaction and injection of the basal Coconino into the Hermit is indicated by 1) macroscopic and microscopic banding (flow structures) within the cracks, 2) bedded sandstone clast breccias in structureless sandstone lenses at the base of the Coconino, 3) lateral sand bodies which are connected to the vertical cracks, 4) a zoned depth distribution of cracks about the Bright Angel Fault zone, 5) insufficient clay mineralogy and particle size for the Hermit to crack by desiccation, 6) preferred orientation of the cracks roughly perpendicular to the Bright Angel Fault zone and several other features. Caution should be exercised when interpreting sand-filled cracks as desiccation features (i.e., "mud cracks"), even if the interpretation fits well with accepted paleoenvironmental models.

Whitmore, John H.; Strom, Ray

2010-10-01

338

Sedimentary structures and textures of Rio Orinoco channel sands, Venezuela and Colombia  

USGS Publications Warehouse

Most sedimentary structures represented in sand bodies of the Rio Orinoco are tabular-planar cross-strata which, together with some wedge-planar cross-strata, are the products of sand-wave deposition. Locally, in areas of river meander where point bars characteristically form, trough structures forming festoon patterns are numerous. At a few localities, sets of nearly horizontal strata occur between tabular-planar sets and are interpreted to be the deposits of very fast currents of the upper flow regime; elsewhere, uncommon lenses and beds of silt, clay, or organic matter consisting of leaves and twigs, seem to be the result of quiet-water settling through gravity. By far the most common grain size represented in the tabular-planar and wedge-planar cross-strata of the sandwave deposits is medium sand (? - ? millimeter) as determined by screen analyses. Many samples, however, also contain moderate quantities of coarse or very coarse sand. Eolian dunes on top of the sand-wave deposits are dominantly fine grained. The river channel sands were determined to be largely moderately well sorted, although in some places they were mostly well sorted, and in others, mostly moderately sorted.

McKee, Edwin Dinwiddie

1989-01-01

339

Biomass gasification with air in a fluidized bed: Effect of the in-bed use of dolomite under different operation conditions  

SciTech Connect

The performance of a biomass gasifier, fluidized-bed type, is improved by in-bed use of calcined dolomite. Tar contents in the raw flue gas below 1 g/m{sub n}{sup 3} are obtained by using a bed with a percentage between 15 and 30 wt% of dolomite (the rest being silica sand). The work is carried out at small pilot-plant scale (10 kg of biomass/h) with equivalence ratios (ER) between 0.20 and 0.35 and temperatures of 800--840 C in the gasifier bed. To replace the eroded and elutriated dolomite (from the gasifier bed), an amount of dolomite (0.40--0.63 mm) is continuously fed, mixed with the biomass at 3 wt%. When the results obtained with in-bed dolomite are compared to the ones gained in a gasifier bed without dolomite, change of the following variables is reported: gas composition and its corresponding heating value, gas and char yields, apparent thermal efficiency, and tar contents. Once the usefulness of the in-bed use of dolomite is established, three main operation variables (ER and temperature of the gasifier bed and freeboard) are studied in the improved gasifier. Carryover of solids from the gasifier also increases when calcined dolomite is used because of its softness. Elutriation rate constants are calculated for several operational parameters.

Gil, J.; Caballero, M.A.; Martin, J.A.; Aznar, M.P.; Corella, J.

1999-11-01

340

Modern shallow-water graded sand layers from storm surges, Bering Shelf: a mimic of Bouma sequences and turbidite systems.  

USGS Publications Warehouse

A sequence of graded sand layers, interbedded with mud, extends offshore over 100km from the Yukon Delta shoreline across the flat, shallow epicontinental shelf of the northern Bering Sea, Alaska. Proximal graded sand beds on the delta-front platform near the shoreline are coarser, thicker and contain more complete vertical sequences of sedimentary structures than distal beds. The sequence of graded sands appears to be related to the major storm surges that occur every several years. The major storms increase the average 10-m water depth in southern Norton Sound as much as 5m and cause fluctuations in pore pressure from wave cyclic loading that may liquefy the upper 2 to 3m of sediment. -from Author

Nelson, C. H.

1982-01-01

341

Wind tunnel observation on the effect of a porous wind fence on shelter of saltating sand particles  

NASA Astrophysics Data System (ADS)

A porous wind fence is an artificial barrier widely employed to abate wind erosion. This study investigated the shelter effect of a porous wind fence on saltating sand in a simulated atmospheric boundary layer (ABL). A wind fence with a porosity ? = 38.5% was installed on a flat bed of sand collected from a beach (diameter, d = 200-300 ?m). A high-speed digital camera was used to capture consecutive images of saltating sand particles around the fence at a frame rate of 4000 frames per second (fps). In addition, the particle tracking velocimetry (PTV) method was employed to extract the instantaneous velocity fields of saltating sand particles. From these data, the mean velocity and volume concentration of saltating sand, mass flux, and kinetic energy were evaluated. As a result, the mean velocities decrease dramatically on the leeward side of the fence, and a high-velocity region exists in the shear layer above the fence. The sand mass flux distributions with height around the fence are represented by an exponential function. Both the particle concentration and mass flux decay largely in the leeward region. The present experimental results can provide useful information to understand sand transport through a porous fence and allow the creation of a new control measure of wind erosion of sand particles.

Zhang, Ning; Kang, Jong-Hoon; Lee, Sang-Joon

2010-08-01

342

EVALUATION OF ANAEROBIC, EXPANDED-BED CONTRACTORS FOR MUNICIPAL WASTEWATER TREATMENT  

EPA Science Inventory

The anaerobic expanded-bed contactors for treating dilute municipal wastes were evaluated. A 334-liter diatomaceous earth, a 334 liter granular activated carbon, a set of two 66-liter sand, and two 3-liter diatomaceous earth reactor systems were used. For the most part the feed w...

343

Bursting phenomenon and incipient motion of solid particles in bed-load transport  

Microsoft Academic Search

In this paper, we present the results of an experimental investigation aiming at understanding the interaction between near-wall coherent structures (or burst) and bedload transport in an open channel flow. This experiment associates Laser Doppler Anemometry measurements of the instantaneous velocity near the wall with real time measurement of sand particle trajectories on the smooth bed of a hydraulic flume.

P. Sechet; B. Le Guennec

1999-01-01

344

Lava Beds National Monument.  

National Technical Information Service (NTIS)

Traces the dramatic genesis of the volcanic features found at Lava Beds National Monument located in Northern California. Animation is intercut with contemporary volcanic footage to reveal how nature's violent forces devastated this area thousands of year...

1994-01-01

345

The Valuation of the Alberta Oil Sands  

Microsoft Academic Search

The Alberta oil sands reserves represent a very valuable energy resource for Canadians. In 2007, Statistics Canada valued the oil sands at $342.1 billion, or 5 per cent Canada's total tangible wealth of $6.9 trillion. Given the oil sands' importance, it is essential to value them appropriately. In this report, we critically review the methods used by Statistics Canada in

Andrew Sharpe; Jean-François Arsenault; Alexander Murray; Sharon Qiao

2008-01-01

346

Foundry Sand Facts for Civil Engineers.  

National Technical Information Service (NTIS)

Metal foundries use large amounts of sand as part of the metal casting process. Foundries successfully recycle and reuse the sand many times in a foundry. When the sand can no longer be reused in the foundry, it is removed from the foundry and is termed f...

2004-01-01

347

Control of bed height in a fluidized bed gasification system  

DOEpatents

In a fluidized bed apparatus a method for controlling the height of the fdized bed, taking into account variations in the density of the bed. The method comprises taking simultaneous differential pressure measurements at different vertical elevations within the vessel, averaging the differential pressures, determining an average fluidized bed density, then periodically calculating a weighting factor. The weighting factor is used in the determination of the actual bed height which is used in controlling the fluidizing means.

Mehta, Gautam I. (Greensburg, PA); Rogers, Lynn M. (Export, PA)

1983-12-20

348

Reservoir characterization for Chevron's HASDrive field trial, Athabasca oil sands area, northeastern Alberta, Canada  

SciTech Connect

Chevron is currently field testing an in-situ thermal recovery process termed Heated Annulus SteamDrive (HASDrive) on the Lower Cretaceous Athabasca tar sand deposit at the Alberta Oil Sands Technology Research Authority (AOSTRA) Underground Test Facility (UTF) site. The HASDrive process applies heat through a subsurface horizontal pipe to the base of the bitumen-rich reservoir sands of the McMurray Formation. A vertical steam-injection well aids in mobilization of the heavy crude and sweeps hydrocarbons toward a horizontal subsurface producing well. To evaluate the HASDrive technology, a geologic model was developed to predict the distribution and geometry of reservoir sands and intervening shales. Core studies indicated deposition took place in an estuarine environment, with sands representing tidal channel deposits and shales relating to tidal flat sedimentation. A thorough program of conventional and special core analysis was done on samples from five wells. Special core analysis consisted of miscibly cleaning samples prior to determination of brine permeability. Vertical and horizontal permeability were determined for massive to cross-bedded sandstone as well as four types of shale-bearing sandstone. Of these four, thin shale beds and shale breccia were more effective in reducing permeability and may form barriers to fluid flow. Thin discontinuous shale laminae or shaly wisps merely impede flow. Interactive workstation programs used core and log data petrophysical parameters as input to build a simulator grid of 2,600 blocks in 10 layers to represent a field trial area of approximately 2,000 m{sup 2}. Potential barriers capable of preventing or reducing the flow rate were identified, incorporated into the model, and treated as dimensionless shales (i.e., shaly beds with negligible thickness). The simulator model was then used to the match history of field trial fluid production.

Chalcraft, R.G.; Grant, C.W. (Chevron Oil Field Research Co., La Habra, CA (USA))

1990-05-01

349

A generalization of Reiner’s mathematical model for wet sand  

SciTech Connect

In this paper we modify the constitutive relation derived by Reiner (1945), to describe dilatancy in wet sand, by suggesting that the shear viscosity would depend on the shear rate and the volume fraction. We then look at the flow of a saturated densely packed bed of particles (with liquid in the pores) between two horizontal flat plates. We obtain exact solutions for a very special case.

Mehrdad Massoudi

2011-01-01

350

Heavy metal removal efficiency in a kaolinite–sand media filtration pilot-scale installation  

Microsoft Academic Search

An experimental study was developed in order to evaluate the efficiency in retention of heavy metal from highway runoff using\\u000a for filter bed current construction materials with known proprieties, sand and kaolinite. The control parameters for the experiments\\u000a were: pH, conductivity, temperature, Zn, Cu, Pb, flow, and hydraulic head.\\u000a \\u000a Preliminary results show that Zn is the most mobile metal with

P Ramísio; J Vieira

351

Trickle-bed reactors  

SciTech Connect

Trickle-bed reactors can be defined as a fixed bed of catalyst particles, contacted by a gas-liquid, two-phase flow. The flow may be cocurrent (downflow or upflow) or countercurrent. In this article, we will focus on cocurrent downflow, which, because of its relatively lower pressure drop and the absence of flooding, is by far the most common mode of operation in industrial practice. Trickle-bed reactors are used primarily in the petroleum industry for hydrocracking, hydrodesulfurization, and hydrodenitrogenation. It is estimated that a significant fraction of all the petroleum processed passes through a trickle-bed reactor in one way or another. Other commercial applications of trickle-bed reactors can be found in the petrochemical industry, involving mainly hydrogenation and oxidation of organic compounds. Because of the industrial significance of this reactor type, a large number of review papers and monographs have appeared in the literature, stressing primarily the development and use of various empirical correlations. For this reason, this aspect of trickle-beds, despite its significance, is not emphasized in this article. Instead, the authors intend to offer an overview of the key concepts and design considerations of this reactor type. They also focus on relevant physical phenomena, particularly particle-level physics, which provides insights for evaluating existing correlations or a given design procedure.

Ng, K.M.; Chu, C.F.

1987-11-01

352

Bed rest and immunity  

NASA Astrophysics Data System (ADS)

Space flight has been shown to result in altered immune responses. The current study was designed to investigate this possibility by using the bed rest model of some space flight conditions. A large number of women are included as subjects in the study. The hypothesis being tested is: 60 days head-down tilt bed rest of humans will affect the immune system and resistance to infection. Blood, urine and saliva samples will be obtained from bed rest subjects prior to, at intervals during, and after completion of 60 days of head-down tilt bed rest. Leukocyte blastogenesis, cytokine production and virus reactivation will be assessed. The ability of the subjects to respond appropriately to immunization with the neoantigen bacteriophage ?X-174 will also be determined. Bed rest is being carried out at MEDES, Toulouse France, and the University of Texas Medical Branch, Galveston, TX. The studies to be carried out in France will also allow assessment of the effects of muscle/bone exercise and nutritional countermeasures on the immune system in addition to the effects of bed rest.

Sonnenfeld, Gerald; Aviles, Hernan; Butel, Janet S.; Shearer, William T.; Niesel, David; Pandya, Utpal; Allen, Christopher; Ochs, Hans D.; Blancher, Antoine; Abbal, Michel

2007-02-01

353

Short communication: Dairy bedding type affects survival of Prototheca in vitro.  

PubMed

Protothecae are algal pathogens, capable of causing bovine mastitis, that are unresponsive to treatment; they are believed to have an environmental reservoir. The role of bedding management in control of protothecal mastitis has not been studied. The purpose of this study was to evaluate the growth of either environmental or mastitis-associated Prototheca genotypes in dairy bedding materials that are commonly used in Maine. Prototheca zopfii genotypes 1 and 2 (gt1 and gt2) were inoculated into sterile broth only (control ), kiln-dried spruce shavings, "green" hemlock sawdust, sand, or processed manure-pack beddings with broth, and incubated for 2 d. Fifty microliters of each isolate was then cultured onto plates and the resulting colonies counted at 24 and 48 h postinoculation. Shavings were associated with significantly less total Prototheca growth than other bedding types. Growth of P. zopfii gt1 was significantly higher than that of gt2 in the manure-pack bedding material. Spruce shavings, compared with manure, sand, or sawdust, may be a good bedding type to prevent growth of Prototheca. Based on these in vitro findings, bedding type may affect Prototheca infection of cattle in vivo. PMID:24119794

Adhikari, N; Bonaiuto, H E; Lichtenwalner, A B

2013-12-01

354

Proppant selection for fracturing and sand control  

SciTech Connect

Starting with definitions of gravel, sand and proppants, this article proceeds to discuss the basic design dilemma of selecting proppant size to achieve the optimum permeability of larger particles vs. higher strength and sand screening ability of smaller sizes. Equations for preventing sand invasion by velocity control are introduced and tables of data give engineers actual design information; tips on table use are included. Hydraulic frac/gravel pack treatments are accepted means of obtaining high well productivity and sand control. A one-step, tip-screenout efficiently creates a short fracture through near-wellbore formation damage and packs the screen/casing annulus to prevent sand production.

Sparlin, D.D.; Hagen, R.W. Jr. (International Completion Consultants Inc., Houston, TX (United States))

1995-01-01

355

A study of infiltration on three sand capillary barriers  

Microsoft Academic Search

The capillary barrier effect was investigated by conducting infiltration tests on three soil columns of fine sand over medium sand, medium sand over gravelly sand, and fine sand over gravelly sand. The barrier effect was ver- ified in the underlying layer of coarser material, and the water-entry values of the coarser layers were confirmed to be nearly equal to the

Hong Yang; H. Rahardjo; E. C. Leong; D. G. Fredlund

2004-01-01

356

Optimization of Solid Circulation Rate in Compartmented Fluidized Bed Gasifier for Power Generation  

NASA Astrophysics Data System (ADS)

The present paper reports the optimization of solid circulation rate (SCR) in Compartmented Fluidized Bed Gasifier (CFBG), an indirectly heated fluidized bed that incorporates two sets of v-valves and risers to control the solid circulation across the two compartments, i.e. combustor and gasifier of a pilot plant scale (the height and ID are 1.8m and 0.66m respectively). Sand was used as inert fluidized by air. Four operating variables were studied i.e. bed height, riser, v-valve and main bed flowrate. Based on 24 full factorial design of experiment in Yates' algorithm, at confidence level >=95%, ANOVA analysis has revealed six important effects. The steepest ascent method was applied on linear regression generated from these effects to design the subsequent optimization experiments. The optimum values of SCR have been estimated for both low and high bed level at specific operating parameters.

Chok, V. S.; Wee, S. K.; Ariffin, M. Z. Mohd.; Gorin, A.; Chua, H. B.; Yan, H. M.

2008-10-01

357

Update on federal tight sands incentive policies  

SciTech Connect

Recognizing the great potential of increased domestic tight sands production in reducing imports of foreign energy, several branches of the federal government have initiated policies to encourage development of this resource. However, these policies have been slow in formulation, and some are potentially in conflict with each other. Two characteristics of tight sands gas have led to it being singled out for special regulatory treatment. Production from tight sands usually requires the implementation of expensive enhanced recovery techniques, such as hydraulic fracturing, to make development commercially feasible. This has limited production from tight sands to approximately 1 tcf annually. Second, tight sands gas resources have the potential for doubling domestic, commercially recoverable natural gas reserves. This study discusses the current status of pricing mechanisms affecting tight sands and emerging trends for tight sands incentives.

Buch, L.

1980-11-01

358

Behavior of Windblown Sand on Mars: Results from Single-Particle Experiments  

NASA Technical Reports Server (NTRS)

Experiments are investigating the behavior of individual sand grains in the high-energy martian aeolian regime. Energy partitioning during impact of a saltating grain determines grain longevity, but it also influences the way in which the bed becomes mobilized by reptation. When single grains of sand are fired into loose beds, the bed can absorb up to 90% of the impact energy by momentum transfer to other grains; it has been discovered that the impacting grains cause circular craters even at low impact angles. Hundreds of grains can be splashed by a single high-velocity (100 m/s) impact causing more bed disturbance through reptation than previously thought. The research is supported by NASA's PG&G Program. Because the martian aeolian environment in both high energy and of long duration, the most mobile fractions of windblown sand should have eradicated themselves by attrition, unless sand supply has kept pace with destruction. It is therefore important to understand the rate of grain attrition in order to make sense of the existence of vast dune fields on Mars. Attrition, has been addressed in other studies, but precise data for a single saltating grain striking a loose bed of sand have not been acquired -- the quintessential case to be understood for dunes on Mars. To acquire these data, we are employing a compound crossbow which has the bolt-firing mechanism replaced with a pneumatically-automated sabot system. The sabot can launch individual grains of sand of any size between several millimeters and about 50 microns, at velocities up to 100m/s. This is around the maximum velocity expected for saltating grains on Mars. The sabot sled is equipped with photoelectric sensors for measuring shot velocity. Baffling of the grain's exit orifice has enabled projection of single grains without significant aerodynamic effects from the sabot. Grains are fired into loose beds of sand at about 15 degrees from the horizontal (typical saltation trajectory at impact) while being filmed on high-speed video. High-intensity pulse illumination for the grains is triggered by the solenoid-operated bow trigger. A 45 degree mirror over the impact site provides simultaneous horizontal and vertical images of the impact on each video frame. UV fluorescence is enabling grain and grain-fragment recovery. At 100 m/s, grains of all sizes shatter into many fragments when the sand is replaced with a solid target. Kinetic energy of the grains at this velocity exceeds the critical energy for catastrophic failure of minerals. Although probably exceptional as a grain speed, it suggests that conditions on Mars might elevate materials into an attrition regime not encountered on other planets; individual grains blown across rock pavements on Mars will have short lifespans. When experimental grains impact loose (dune) sand, much, if not most of the kinetic energy is converted into momentum of other grains. Using high-speed filming, the energy involved in splashing grains at the impact site can be derived from the size of the crater, the speed of the splashed grains, and the rebound speed of the impactor. The amount of energy partitioned into material failure (as opposed to momentum) is too small a fraction of the total to be calculated under these circumstances. This does not necessarily mean that little damage occurs to the grains (the full extent of the damage has yet to be determined) because only a small fraction of the impact energy is required for inducing brittle fracture. Damage is orders of magnitude less than during impact against solid surfaces.

Marshall, J. R.; Borucki, J.; Sagan, C.

1999-01-01

359

Thermal Properties of oil sand  

NASA Astrophysics Data System (ADS)

Thermal recovery methods such as Cyclic Steam Injection or Steam Assisted Gravity Drainage (SAGD) are the effective methods for producing heavy oil or bitumen. In any thermal recovery methods, thermal properties (e.g., thermal conductivity, thermal diffusivity, and volumetric heat capacity) are closely related to the formation and expansion of steam chamber within a reservoir, which is key factors to control efficiency of thermal recovery. However, thermal properties of heavy oil or bitumen have not been well-studied despite their importance in thermal recovery methods. We measured thermal conductivity, thermal diffusivity, and volumetric heat capacity of 43 oil sand samples from Athabasca, Canada, using a transient thermal property measurement instrument. Thermal conductivity of 43 oil sand samples varies from 0.74 W/mK to 1.57 W/mK with the mean thermal conductivity of 1.09 W/mK. The mean thermal diffusivity is 5.7×10-7 m2/s with the minimum value of 4.2×10-7 m2/s and the maximum value of 8.0×10-7 m2/s. Volumetric heat capacity varies from 1.5×106 J/m3K to 2.11×106 J/m3K with the mean volumetric heat capacity of 1.91×106 J/m3K. In addition, physical and chemical properties (e.g., bitumen content, electric resistivity, porosity, gamma ray and so on) of oil sand samples have been measured by geophysical logging and in the laboratory. We are now proceeding to investigate the relationship between thermal properties and physical/chemical properties of oil sand.

LEE, Y.; Lee, H.; Kwon, Y.; Kim, J.

2013-12-01

360

Perchlorate removal in sand and plastic media bioreactors.  

PubMed

The treatment of perchlorate-contaminated groundwater was examined using two side-by-side pilot-scale fixed-bed bioreactors packed with sand or plastic media, and bioaugmented with the perchlorate-degrading bacterium Dechlorosoma sp. KJ. Groundwater containing perchlorate (77microg/L), nitrate (4mg-NO(3)/L), and dissolved oxygen (7.5mg/L) was amended with a carbon source (acetic acid) and nutrients (ammonium phosphate). Perchlorate was completely removed (<4microg/L) in the sand medium bioreactor at flow rates of 0.063-0.126L/s (1-2gpm or hydraulic loading rate of 0.34-0.68L/m(2)s) and in the plastic medium reactor at flow rates of <0.063L/s. Acetate in the sand reactor was removed from 43+/-8 to 13+/-8mg/L (after day 100), and nitrate was completely removed in the reactor (except day 159). A regular (weekly) backwashing cycle was necessary to achieve consistent reactor performance and avoid short-circuiting in the reactors. For example, the sand reactor detention time was 18min (hydraulic loading rate of 0.68L/m(2)s) immediately after backwashing, but it decreased to only 10min 1 week later. In the plastic medium bioreactor, the relative changes in detention time due to backwashing were smaller, typically changing from 60min before backwashing to 70min after backwashing. We found that detention times necessary for complete perchlorate removal were more typical of those expected for mixed cultures (10-18min) than those for the pure culture (<1min) reported in our previous laboratory studies. Analysis of intra-column perchlorate profiles revealed that there was simultaneous removal of dissolved oxygen, nitrate, and perchlorate, and that oxygen and nitrate removal was always complete prior to complete perchlorate removal. This study demonstrated for the first time in a pilot-scale system, that with regular backwashing cycles, fixed-bed bioreactors could be used to remove perchlorate in groundwater to a suitable level for drinking water. PMID:14630102

Min, Booki; Evans, Patrick J; Chu, Allyson K; Logan, Bruce E

2004-01-01

361

Thermal recovery from tar sands  

SciTech Connect

On the basis of the progress made in developing improved technology for recovery of bitumen from tar sands, it is logical to assume that as the world's supply of light and heavy oil is depleted, production of synthetic oil from the bitumen resources in tar sands will accelerate. As most of the known deposits of tar sands were discovered by accident, there is reason to believe that a worldwide exploration program based on sound geological principles will discover much more of this material. The long lead times required to turn this massive resource into acceptable alternative refinery feedstock at a reasonable price make it imperative that we vigorously pursue the development of recovery technology at this time if we are to avoid shortages of liquid fuel early in the next century. There is no question that the light-crude-oil substitute developed from this resource will be more expensive than the conventional light and heavy crudes being used today. However, there is reason to believe that the differential in costs will narrow as the search for new sources of light oil swings to deeper targets in more remote and hostile environments, such as the continental shelves and arctic islands, and more expensive enhancedrecovery techniques are used to recover the oil now left behind in deep depleted light- and heavy-oil reservoirs.

Carrigy, M.A.

1983-12-01

362

DCS of Syrtis Major Sand Migration  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released August 2, 2004 This image shows two representations of the same infra-red image of craters and lava flow features in Syrtis Major. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

The prominent rim of the large crater at the top of the image is blocking migrating sand from entering the crater. This produces a very distinct compositional boundary between the pink/magenta basaltic sand and the green dust covering the crater rim and floor. Many of the smaller craters in this region have dust trails behind them, indicating the prevailing wind direction. At the top of the image, the prevailing wind direction is to the northwest, while at the bottom of the image, the prevailing winds have shifted towards the southwest.

Image information: IR instrument. Latitude 9.2, Longitude 68.4 East (291.6 West). 100 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

363

Conduits to Catchments: Deformation Band Faults in Arid and Semi-Arid Vadose Zone Sands  

NASA Astrophysics Data System (ADS)

Where fault movement intercepts sandy sediments, deformational processes create narrow, tabular zones of reduced pore and grain sizes, called deformation band faults, which possess markedly different hydraulic properties than the parent sands. These faults are commonly found where tectonic extension and erosion have combined to create basins containing variably lithified, heterolithic sediments, which in turn form thick vadose and saturated zones. Under arid or semi-arid conditions the unsaturated property differences between these faults and their poorly lithified parent sands appear to be large enough that the faults can potentially act as paths for preferential flow and transport, or as liquid phase catchments, depending on the conditions. We measured the unsaturated hydraulic properties of three small-displacement normal faults and adjacent sands found in the Bosque del Apache Wildlife Refuge, central New Mexico, USA using UFA centrifuge systems. Fits to commonly used unsaturated property models revealed consistent differences between sands and faults. Analytical one-dimensional models of steady infiltration, exfiltration, and solute transport confirm that faults can become paths for preferential flow and transport. Under dry conditions and observed fault spatial densities, faulted sands can infiltrate and exfiltrate orders of magnitude more liquid phase water than unfaulted sands. Solute residence times are two to four orders of magnitude shorter through faulted than unfaulted sand beds and diagenetic alteration is far more likely to occur in faults than sands because faults are predicted to transmit as many as 10 4 pore volumes in the time needed to transmit a single pore volume through the sand. Numerical modeling of steady two dimensional downwards flow near a dipping fault suggests that, under relatively wet conditions, faults with sufficiently low dip angles can intercept enough water to form sizeable zones of increased water content in the hanging wall. These wetter zones can act as fast paths for subsequent water or solute pulses. Deformation band faults can thus act as catchments under relatively wet vadose zone conditions and as conduits under much drier conditions. In either case, faults can significantly increase water and solute transport through sandy beds in arid and semi-arid vadose zones.

Sigda, J. M.; Wilson, J. L.; Goodwin, L. B.; Conca, J. L.

2002-12-01

364

Facies and environment of the Leckkogel beds (Carnian;Alps)  

Microsoft Academic Search

The Carnian Leckkogel beds represent a carbonate sequence, which was deposited in front of an actively spreading carbonate\\u000a platform.\\u000a \\u000a The typical Leckkogel beds are characterized by highly diverse sponge buildups. Sphinctozoan sponges predominate together\\u000a with rare bryozoans and hydrozoans as well as red algae and thin crusts of cyanophyceans. Foraminifera are very rare and dasycladaceans\\u000a are missing altogether.\\u000a \\u000a \\u000a \\u000a Oncoidal limestones

Wolf-Christian Dullo; Richard Lein

1982-01-01

365

Conservation and management of northeast Atlantic and Mediterranean maerl beds  

Microsoft Academic Search

ABSTRACT 1. Maerl beds occur worldwide,and are formed,by an accumulation,of unattached,calcareous red algae (Rhodophyta). 2. Maerl-forming algae grow,in a superficial living layer on sediments,within the photic zone. 3. Maerl beds are spatially complex,habitats with a high degree of species and,trophic group diversity. 4. The European,Commission’s ‘Habitats Directive’ mandates,the conservation,management,of two of the main European maerl-forming species, Phymatolithon calcareum and Lithothamnion

C. Barbera; C. Bordehore; J. A. Borg; J. Grall; J. M. Hall-Spencer; Ch. de la Huz; E. Lanfranco; M. Lastra; P. G. Moore; J. Mora; M. E. Pita; M. Rizzo; A. Seva; P. J. Schembri; C. Valle

2003-01-01

366

Mariculture of Red Seaweeds.  

National Technical Information Service (NTIS)

As new applications for using red seaweed have developed, the demand for red seaweed has increased, to the point where commercial harvesting techniques now need to be developed to lessen dependence on wild seaweed stocks. The history of red seaweed use as...

J. E. Hansen J. E. Packard W. T. Doyle

1981-01-01

367

Red-Cockaded Woodpecker.  

National Technical Information Service (NTIS)

The red-cockaded woodpecker (RCW) is a small bird measuring about 7 inches in length. Identifiable by its white cheek patch and black and white barred back, the males have a few red feathers, or cockade. These red feathers usually remain hidden underneath...

2002-01-01

368

RED-LETTER DAYS  

EPA Science Inventory

The word "red-letter" is an adjective meaning "of special significance." It's origin is from the practice of marking Christian holy days in red letters on calendars. The "red-letter days" to which I refer occurred while I was a graduate student of ...

369

Direct combustion of olive cake using fluidized bed combustor  

SciTech Connect

A fluidized bed combustor of 0.146 m diameter and 1 m length was fabricated from stainless steel to burn olive cake. Initially, and in order to obtain fluidization, the system was operated under cold conditions using a sand with particle size in the range of 500 to 710 microns. The continuous combustion experiments were carried out under controlled conditions, such that the effects of bed temperature, olive cake feed rate, fluidization velocity, and particle size on combustion efficiency and flue gas composition were investigated. It was found that the combustion efficiency decreases with the bed temperature, fluidization velocity, and the feed rate, while it increases with the particle size used. Further, the gas products analysis carried out using a gas chromatography analyzer have shown a nonmeasured amount of SO{sub 2}, and small amounts of CO. Finally, the temperature distribution along the bed indicated that the temperature throughout the bed is fairly uniform, demonstrating a good mixing of reactants, which is important for efficient combustion.

Khraisha, Y.H.; Hamdan, M.A.; Qalalweh, H.S. [Univ. of Jordan, Amman (Jordan). Faculty of Engineering and Technology

1999-05-01

370

Experimental and numerical investigations on degradation of channel bed of cohesive sediment mixtures  

NASA Astrophysics Data System (ADS)

Experimental observations on a degradation profile of channel beds consisting of cohesive sediment mixtures are presented. The sediment used for the experimentation consisted of fine gravel mixed with clay in varying proportions (10%-50% by weight) and fine gravel and fine sand in equal proportions mixed with varying proportions of clay (10%-50% by weight). The clay percentage in bed material and unconfined compressive strength of channel bed were found to be the main factors controlling the depth of degradation of channel bed of cohesive sediment mixtures, as degradation depth reduces considerably with an increase in clay percentage and unconfined compressive strength of sediment bed. An algorithm is also proposed to compute transient bed and water surface profiles in a channel bed made up of such cohesive sediment mixtures. For this purpose the predictor-corrector-based, essentially nonoscillatory finite difference numerical scheme is utilized for the solution of governing equations through the use of appropriate initial and boundary conditions. The recently proposed relationships by the authors for bed and suspended load transport of cohesive sediment mixtures were used as the auxiliary equations in the proposed algorithm. The observations on degradation of channel beds consisting of such cohesive sediment mixtures have not been reported so far in the literature to the best of our knowledge.

Kothyari, Umesh C.; Jain, Rajesh K.

2010-12-01

371

Removal of lead ions by keramzite sand coated with electroplating sludge under dynamic conditions.  

PubMed

Column studies were performed to determine the effect of bed height, linear flow rate, adsorbent particle size and initial metal ion concentration on lead removal by keramzite sand coated with electroplating sludge. The Bed depth service time (BDST) model applied to the data at 2% breakthrough gave the best approximation to the experimental results compared with other investigated breakthrough points. The adsorption performance of the thermally modified coated keramzite columns could be well described by the Wolborska model up to 50% breakthrough point. The application of this model allowed determination of the kinetic coefficients of external mass transfer in the fixed bed and the time for protective action of the sorbent layers. The experimental results support the assumption that the external mass transfer of the solute through the hydrodynamic boundary layer is the rate-limiting step. It has been established that the keramzite sand coated with electroplating sludge (particle size 0.5-0.8 mm) can be successfully used for lead removal from dilute metal ion solutions at linear flow rate 4-6 cm/min and empty bed contact time > or = 3 min. PMID:11759900

Stefanova, R Y

2001-01-01

372

Cardiovascular consequences of bed rest: effect on maximal oxygen uptake  

NASA Technical Reports Server (NTRS)

Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake and reserve capacity to perform physical work.

Convertino, V. A.

1997-01-01

373

Treatment bed microbiological control  

NASA Technical Reports Server (NTRS)

The effects of microbial fouling on treatment bed (TB) performance are being studied. Fouling of activated carbon (AC) and ion exchange resins (IEX) by live and devitalized bacteria can cause decreased capacity for selected sorbates with AC and IEX TB. More data are needed on organic species removal in the trace region of solute sorption isotherms. TB colonization was prevented by nonclassical chemical disinfectant compositions (quaternary ammonium resins) applied in suitable configurations. Recently, the protection of carbon beds via direct disinfectant impregnation has shown promise. Effects (of impregnation) upon bed sorption/removal characteristics are to be studied with representative contaminants. The potential need to remove solutes added or produced during water disinfection and/or TB microbiological control must be investigated.

Janauer, Gilbert E.; Fitzpatrick, Timothy W.; Kril, Michael B.; Wilber, Georgia A.; Sauer, Richard L.

1987-01-01

374

The Bed & Breakfast Channel  

NSDL National Science Digital Library

With this site, founders Eric and Liz Goldreyer provide travelers with "comprehensive, user-friendly, up-to-date information on bed and breakfasts and inns" via the Internet. The primary focus is on providing access to bed and breakfast listings in North America (over 20,000), although there is also a growing collection of listings from around the world. In the Quick Search, users may search for accommodations by city, state or country. Users who don't have a specific destination in mind, can browse geographically with the World Search. Basic entries include the name, address, and phone number, as well as a link to a city map. Bed and breakfast owners may include additional information, photos, or a link to their own web site, for a fee.

375

[Environmental toxicity of waste foundry sand].  

PubMed

The metal leaching characteristics and volatile organic compounds (VOCs) of five different types of waste foundry sands were analyzed with the toxicity characteristic leaching procedure (TCLP) and head space-gas chromatography (HS-GC). Microtox and soil dehydrogenase activity (DHA) tests were then used to evaluate the bio-effects of these waste sands. The results showed that due to the different metals poured and casting materials used to make the sand molds, there was significant difference among the five waste foundry sands in the compositions and concentrations of metal and organic pollutants. The concentrations of Fe in the leachates of iron and steel casting waste foundry sand exceeded the maximal allowable concentrations specified in the National Standard of Drinking Water Quality, whereas the As concentration in the leachate of aluminum casting waste foundry sand exceeded the standard. The five waste foundry sands had quite different compositions and levels of VOCs, which resulted in different levels of inhibition effects on the luminescent bacteria (30% and 95%). Additionally, the soil DHA tests suggested that metal pollutants in waste foundry sands may inhibit the soil microbial activity, whereas organics in the sands may slightly promote the microbial activity. The results of this study indicated that the waste foundry sands may pose considerable threat to the environment when improperly disposed. PMID:23745431

Zhang, Hai-Feng; Wang, Yu-Jue; Wang, Jin-Lin; Huang, Tian-You; Xiong, Ying

2013-03-01

376

Apparatus for controlling fluidized beds  

DOEpatents

An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

Rehmat, A.G.; Patel, J.G.

1987-05-12

377

Apparatus for controlling fluidized beds  

DOEpatents

An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

Rehmat, Amirali G. (Westmont, IL); Patel, Jitendra G. (Bolingbrook, IL)

1987-05-12

378

Fluid bed material transfer method  

DOEpatents

A fluidized bed apparatus comprising a pair of separated fluid bed enclosures, each enclosing a fluid bed carried on an air distributor plate supplied with fluidizing air from below the plate. At least one equalizing duct extending through sidewalls of both fluid bed enclosures and flexibly engaged therewith to communicate the fluid beds with each other. The equalizing duct being surrounded by insulation which is in turn encased by an outer duct having expansion means and being fixed between the sidewalls of the fluid bed enclosures.

Pinske, Jr., Edward E. (Akron, OH)

1994-01-01

379

The Red Kite  

NSDL National Science Digital Library

The Gigrin, a family-run sheep farm in Wales with a conservation mindset, offers this Web site devoted to the red kite, a small raptor that humans have attempted to protect longer than for any other bird species in the world. Readers can expect a solid introduction to red kite natural history, and an encouraging example of conservation by private landowners. The main Web page provides a general background information about the red kite, including a short audio clip of a red kite call. The following pages contain photos, detailed descriptions of nesting and feeding habits, and links to other organizations involved in protecting the red kite.

380

The Red Kite  

NSDL National Science Digital Library

The Gigrin, a family-run sheep farm in Wales with a conservation mindset, offers this Web site devoted to the red kite, a small raptor that humans have attempted to protect longer than for any other bird species in the world. Readers can expect a solid introduction to red kite natural history, and an encouraging example of conservation by private landowners. The main Web page provides a general background information about the red kite, including a short audio clip of a red kite call. The following pages contain photos, detailed descriptions of nesting and feeding habits, and links to other organizations involved in protecting the red kite.

2008-06-13

381

Staged fluidized bed  

DOEpatents

The invention relates to oil shale retorting and more particularly to staged fluidized bed oil shale retorting. Method and apparatus are disclosed for narrowing the distribution of residence times of any size particle and equalizing the residence times of large and small particles in fluidized beds. Particles are moved up one fluidized column and down a second fluidized column with the relative heights selected to equalize residence times of large and small particles. Additional pairs of columns are staged to narrow the distribution of residence times and provide complete processing of the material.

Mallon, R.G.

1983-05-13

382

Genetic features of soils on marine sands and their windblown derivatives on the White Sea coast (the Kola Peninsula)  

NASA Astrophysics Data System (ADS)

The Quaternary deposits on the Tersk coast of the White Sea are represented by marine deposits (the Tersk sands) enriched in the sea-sorted eluvium of the red Tersk sandstone. These deposits and the soils developed from them are characterized by the predominance of the fine sand fraction and the absence of gravel and the coarser fractions. The sediments derived from the red Tersk sandstone have an impoverished chemical composition (the silica content reaches 75-80%). The iron-illuvial podzols developed from them are characterized by the slightly pronounced differentiation of the main oxides and by the eluvial-illuvial redistribution of the amorphous Al and Fe compounds. Sandy soils—psammozems—with undifferentiated soil profiles are developed from windblown sands subjected to afforestation and from coastal marine sands under a relatively thin natural plant cover. Iron-illuvial podzols buried under a thin sand layer preserve the Al-Fe-humus type of the profile differentiation. In the recently deposited sand layer, the eluvial-illuvial redistribution of the chemical elements is absent.

Pereverzev, V. N.; Kazakov, L. A.; Chamin, V. A.

2011-01-01

383

Advanced Atmospheric Fluidized-Bed Combustion Design - Spouted Bed.  

National Technical Information Service (NTIS)

This report describes the Spouted-Fluidized Bed Boiler that is an advanced atmospheric fluidized bed combustor (FBC). The objective of this system design study is to develop an advanced AFBC with improved performance and reduced capital and operating cost...

F. W. Shirley R. D. Litt

1985-01-01

384

Co-firing of sugar cane bagasse with rice husk in a conical fluidized-bed combustor  

Microsoft Academic Search

This paper presents experimental results on co-firing of ‘as-received’ sugar cane bagasse and rice husk in a conical fluidized-bed combustor (FBC) using silica sand as the bed material. Axial temperature, O2, CO2, CO and NO concentration profiles in the conical FBC operated at 82.5–82.8kg\\/h fuel feed rate and various values of excess air (of about 40, 60, 80 and 100%)

V. I. Kuprianov; K. Janvijitsakul; W. Permchart

2006-01-01

385

Does a large coal particle in a hot fluidised bed lose its volatile content according to the shrinking core model?  

Microsoft Academic Search

Near-spherical particles (diameter ?14 mm) of six different coals (ranging in rank from an anthracite to a lignite) were immersed in turn in an electrically heated bed of sand fluidised by nitrogen. Such a bubbling fluidised bed (U\\/Umf=3.0) was held at a fixed temperature between 750 and 950?°C. A coal particle in such a situation decomposes in the overall reaction: coal?volatile

Jyuung-Shiauu Chern; Allan N. Hayhurst

2004-01-01

386

Lithostratigraphic analysis of sand and silt facies from NGHP 01 gas hydrate accumulations in the Krishna-Godavari Basin  

NASA Astrophysics Data System (ADS)

In 2006, an international effort led by the Indian National Gas Hydrate Program (NGHP) and the U.S. Geological Survey conducted the first large-scale exploration of gas hydrate accumulations. Seven sites were drilled within the Krishna-Godavari (KG) basin, a large syn-tectonic rift basin off the eastern shore of India, with the deepest hole penetrating ~300 mbsf. The sedimentary section in the KG basin includes up to 7 kilometers of Late Carboniferous to Holocene sediments from which commercial oil and natural gas production has been established. Detailed lithologic descriptions and physical properties measurements obtained from cores were combined with electrical log data to characterize the sedimentology and stratigraphy at each site. Our analyses indicate that sediments within the Gas Hydrate stability zone (GHSZ) in the KG basin record a Quaternary (<2MYA) history of deposition dominated by dark grey to black colored nannofossil bearing to rich clay and silty clay sourced from the nearby Krishna and Godavari Rivers. Relatively minor amounts of silt to fine sand beds and lamina (1-5 cm thick) were also observed as well as visible terrestrial organic material. The most pervasive mode of gas hydrate occurrence observed during NGHP-01 in the KG basin sites were disseminated hydrates in low-permeability silt-clay facies. Secondary gas hydrate accumulations were recovered in fracture fill, nodular and lens-like occurrences, or as pore-filling cement in the more permeable sand-silt beds and lamina. Thin sand beds and lamina were recovered at 6 of the 7 sites in the KG basin. ~330 sand beds were reported for all 6 sites with a typical bed thickness of ~3 cm. Net sand to gross sediment ratios ranged from 0.026 to 0.405. No major sand beds (>1 m thick) were recovered at any of the sites. Underlying the GHSZ in the KG basin are Pliocene and Pleistocene age sediments deposited during low-stand conditions. However, rising sea-level from the late Pleistocene to the present resulted in a gradual decrease in the volume of coarse grained material transported across the shelf, and slope related deposition during the Holocene has largely been controlled by episodic failure of shelf-edge deltaic deposits via turbidity flows in slope channels. At two KG sites, significantly greater net sand to gross sediment ratios were observed, perhaps indicating a closer proximity of those sites to turbidite channel-levee systems. While the channels may contain sand facies, given the slope dominant location of the NGHP well locations, it is likely that transported sand bypassed the well sites and was deposited in base-of-slope fans in deeper water to the east. Therefore, exploration for gas hydrate-bearing sands in the KG region should focus on the identification and location of the slope levee sand deposits or toe of slope sand rich fans within the GHSZ. gas/FutureSupply/MethaneHydrates/projects/DOEProjects/NETL-

Rose, K. K.; Boswell, R. M.; Johnson, J.; Nghp 01, S.

2008-12-01

387

Sand as a stable and sustainable resource for nourishing the Mississippi River delta  

NASA Astrophysics Data System (ADS)

The Mississippi River delta is undergoing a catastrophic drowning, whereby 5,000 km2 of low-lying wetlands have converted to open water over at least the past eight decades, as a result of many anthropogenic and natural factors. Continued net land loss has been thought inevitable due to a decline in the load of total suspended sediment--both sand and mud--carried by the river. However, sand--which accounts for ~50-70% of modern and ancient Mississippi delta deposits but comprises only ~20% of the sampled portion of the total load--could be more important than mud for subaerial delta growth. Historically, half of the Mississippi River sediment load is supplied by the Missouri River. Here we analyse suspended sediment load data from two locations downstream from the lowest Missouri River dam to show that the measured sand load in the lower 1,100 km of the Mississippi River has not significantly diminished since dam construction. A one-dimensional numerical model of river morphodynamics predicts that the sand load feeding the delta will decrease only gradually over the next several centuries, with an estimated decline from current values of no more than about 17% within the coming six centuries. We conclude that the lower Mississippi River channel holds a significant reservoir of sand that is available to replenish diminished loads via bed scour and substantially mitigate land loss.

Nittrouer, Jeffrey A.; Viparelli, Enrica

2014-05-01

388

Forensic source differentiation of petrogenic, pyrogenic, and biogenic hydrocarbons in Canadian oil sands environmental samples.  

PubMed

To facilitate monitoring efforts, a forensic chemical fingerprinting methodology has been applied to characterize and differentiate pyrogenic (combustion derived) and biogenic (organism derived) hydrocarbons from petrogenic (petroleum derived) hydrocarbons in environmental samples from the Canadian oil sands region. Between 2009 and 2012, hundreds of oil sands environmental samples including water (snowmelt water, river water, and tailings pond water) and sediments (from river beds and tailings ponds) have been analyzed. These samples were taken from sites where assessments of wild fish health, invertebrate communities, toxicology and detailed chemistry are being conducted as part of the Canada-Alberta Joint Oil Sands Monitoring Plan (JOSMP). This study describes the distribution patterns and potential sources of PAHs from these integrated JOSMP study sites, and findings will be linked to responses in laboratory bioassays and in wild organisms collected from these same sites. It was determined that hydrocarbons in Athabasca River sediments and waters were most likely from four sources: (1) petrogenic heavy oil sands bitumen; (2) biogenic compounds; (3) petrogenic hydrocarbons of other lighter fuel oils; and (4) pyrogenic PAHs. PAHs and biomarkers detected in snowmelt water samples collected near mining operations imply that these materials are derived from oil sands particulates (from open pit mines, stacks and coke piles). PMID:24632369

Wang, Zhendi; Yang, C; Parrott, J L; Frank, R A; Yang, Z; Brown, C E; Hollebone, B P; Landriault, M; Fieldhouse, B; Liu, Y; Zhang, G; Hewitt, L M

2014-04-30

389

Experimental characterization of ceramic pebble beds  

NASA Astrophysics Data System (ADS)

Several materials have been developed in Europe and Japan for the DEMO reactor that will be tested in ITER. The paper describes a solid breeder for nuclear fusion reactor exploiting ceramic pebbles made of Lithium Orthosilicate (Li 4SiO 4) and Lithium metatinate (Li 2TiO 3), with a diameter ranging between 0.5 mm and 1 mm. The main advantages of the pebbles are resistance to thermal stresses and the possibility to easily fill the complex geometries of the blanket. The results of experimental tests are presented, which enable the determination of the behaviour of single pebbles under compression and the parameters of the pebble beds needed to define their constitutive equations. Several standard tests on samples of pebble beds were performed: triaxial, direct shear and compression. The parameters of the Cam-Clay model were obtained from these tests. This model is normally used to describe soil materials (clay, sand) but in our case was used to simulate the triaxial tests with a finite elements computer code. The numerical results show a good agreement with the theoretical ones. Therefore this model could be used to determine the mechanical behaviour of the solid breeding blanket under normal and accidental conditions.

Zaccari, N.; Aquaro, D.

2009-04-01

390

Red Fork sandstone of Oklahoma: depositional history and reservoir distribution  

SciTech Connect

The Middle Pennsylvanian Red Fork sandstone formed as a result of progradation across eastern Kansas and most of Oklahoma. The Red Fork is one of several transgressive-regressive sequences (cyclothems) developed within the Desmoinesian Cherokee Group. Sea level changes, together with varying subsidence, were dominant factors controlling the general stratigraphic (correlative) characteristics of the Red Fork interval. Progradation was episodic, with sand deposition in the more active part of the basin during lower sea level stands and valley-fill deposition in the more stable areas during sea level rises. A map of Red Fork sand trends reveals an alluvial-deltaic complex covering most of Oklahoma. The Red Fork consists primarily of alluvial-valley and plain (fluvial) bodies in the northernmost part of northeastern Oklahoma, alluvial-deltaic bodies in most of the remaining parts of the shelf area, and off-shelf submarine-fan and slope basinal-floor complexes within the deeper part of the Anadarko basin. Determination of reservoir trend and genesis requires integration of rock and log data. Logs need to be calibrated to cores in order to estimate depositional environments accurately and to make a reasonable assessment of diagenetic overprints. Much of the oil and gas has been trapped in stratigraphic traps, and a significant amount of oil is in channel sandstones with trends at high angles to the structural grain. In some areas, secondary clay, in particular chloritic clay, has resulted in microporosity, high water saturation, and correspondingly low resistivities in oil reserves.

Shelton, J.W.; Fritz, R.D.; Johnson, C.

1989-03-01

391

ELECTRIFIED BED EVALUATION  

EPA Science Inventory

The report gives results of an evaluation of a prototype electrified bed (EFB) particulate collection device. The 500 cfm unit, which uses mechanical and electrical mechanisms for collection, was installed at an asphalt roofing plant during the tests. Fractional efficiency was de...

392

Bed rest during pregnancy  

MedlinePLUS

... that each day of bed rest brings you one day closer to the birth. In the meantime, try to: Get organized. Make sure what you need is within reach -- like a phone, laptop, drinks and snacks, the remote control, and extra ...

393

Fluidized Bed Coal Liquefaction.  

National Technical Information Service (NTIS)

Coal is catalytically hydropyrolyzed at temperatures of 500 C to 700 C and pressures of 1000 psi to 4000 psi to form a liquefied product comprising gasoline and middle distillate fuel and diesel oils by forming a fluidized bed of coal in hot hydrogen or h...

S. A. Qader

1983-01-01

394

Bed wetting at home  

MedlinePLUS

... but this alone is not a treatment for bed wetting. You should not restrict fluids too much. Also have your child avoid drinks ... Your child has been drinking excess amounts of fluids Your child has ... or shy, or suddenly behaving in a sexually suggestive way)

395

Technology test bed review  

NASA Technical Reports Server (NTRS)

The topics are presented in viewgraph form and include the following: (1) Space Shuttle Main Engine (SSME) technology test bed (TTB) history; (2) TTB objectives; (3) TTB major accomplishments; (4) TTB contributions to SSME; (5) major impacts of 3001 testing; (6) some challenges to computational fluid dynamics (CFD); (7) the high pressure fuel turbopump (HPFTP); and (8) 3001 lessons learned in design and operations.

Mcconnaughey, H. V.

1992-01-01

396

EXPANDED BED BIOLOGICAL TREATMENT  

EPA Science Inventory

A three-year pilot-scale research investigation at the EPA Lebanon Pilot Plant was conducted to evaluate the feasibility of a unique biological secondary treatment process, designated the Expanded Bed Biological Treatment Process (EBBT). The EBBT process is a three-phase (oxygen/...

397

Direct laser sintering of a silica sand  

Microsoft Academic Search

As an application study of rapid prototyping, commercially available silica sand was successfully direct-laser-sintered in a self-developed high-temperature laser sintering equipment. The mechanism of powder-state sand becoming a solid state block during the laser sintering process was disclosed by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis on sand particles and sintered samples. The effect of process parameters

Y. Tang; J. Y. H. Fuh; H. T. Loh; Y. S. Wong; L. Lu

2003-01-01

398

Visual accumulation tube for size analysis of sands  

USGS Publications Warehouse

The visual-accumulation-tube method was developed primarily for making size analyses of the sand fractions of suspended-sediment and bed-material samples. Because the fundamental property governing the motion of a sediment particle in a fluid is believed to be its fall velocity. the analysis is designed to determine the fall-velocity-frequency distribution of the individual particles of the sample. The analysis is based on a stratified sedimentation system in which the sample is introduced at the top of a transparent settling tube containing distilled water. The procedure involves the direct visual tracing of the height of sediment accumulation in a contracted section at the bottom of the tube. A pen records the height on a moving chart. The method is simple and fast, provides a continuous and permanent record, gives highly reproducible results, and accurately determines the fall-velocity characteristics of the sample. The apparatus, procedure, results, and accuracy of the visual-accumulation-tube method for determining the sedimentation-size distribution of sands are presented in this paper.

Colby, B. C.; Christensen, R. P.

1956-01-01

399

Vacuum Head Removes Sanding Dust: Tool removes dust as it sands.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A modified sanding block scoops up the dust it creates and delivers it to a vacuum exhaust tube. The block sands, shapes, or polishes without introducing contaminati...

1982-01-01

400

A branching process model for sand avalanches  

SciTech Connect

An analytically solvable model for sand avalanches of noninteracting grains of sand, based on the Chapman-Kolmogorov equations, is presented. For a single avalanche, distributions of lifetimes, sizes of overflows and avalanches, and correlation functions are calculated. Some of these are exponentials, some are power laws. Spatially homogeneous distributions of avalanches are also studied. Computer simulations of avalanches of interacting grains of sand are compared to the solutions to the Chapman-Kolmogorov equations. It is found that within the range of parameters explored in the simulation, the approximation of noninteracting grains of sand is a good one. 20 refs., 4 figs.

Garcia-Pelayo, R.; Salazar, I.; Schieve, W.C. (Univ. of Texas, Austin (United States))

1993-07-01

401

Central Asian sand seas climate change as inferred from OSL dating  

NASA Astrophysics Data System (ADS)

Luminescence dating techniques have become more accessible, widespread, more accurate and support studies of climate change. Optically stimulated luminescence (OSL) is used to determine the time elapsed since quartz grains were last exposed to sunlight, before they were buried and the dune stabilized. Many sand seas have been dated extensively by luminescence, e.g., the Kalahari, Namib the Australian linear dunes and the northwestern Negev dune field, Israel. However, no ages were published so far from the central Asian sand seas. The lack of dune stratigraphy and numerical ages precluded any reliable assessment of the paleoclimatic significance of dunes in central Asia. Central Asian Sand seas (ergs) have accumulated in the Turan basin, north-west of the Hindu Kush range, and span from south Turkmenistan to the Syr-Darya River in Kazakhstan. These ergs are dissected by the Amu-Darya River; to its north lies the Kyzylkum (red sands) and to its south lies the Karakum (black sands). Combined, they form one of the largest sand seas in the world. This area is understudied, and little information has been published regarding the sands stabilization processes and deposition ages. In this study, OSL ages for the Karakum and Kyzylkum sands are presented and analysis of the implications of these results is provided. Optical dates obtained in this study are used to study the effects climatic changes had on the mobility and stability of the central Asian sand seas. Optically stimulated luminescence ages derived from the upper meter of the interdune of 14 exposed sections from both ergs, indicate extensive sand and dune stabilization during the mid-Holocene. This stabilization is understood to reflect a transition to a warmer, wetter, and less windy climate that generally persisted until today. The OSL ages, coupled with a compilation of regional paleoclimatic data, corroborate and reinforce the previously proposed Mid-Holocene Liavliakan phase, known to reflect a warmer, wetter, and less windy climate that persists until today and resulted in dune stabilization around the Mid-Holocene. This study, solidifies our results regarding the Kyzylkum and Karakum sand seas dynamics, ages, and emphasizes the importance of regional climatic control on aeolian activity.

Maman, Shimrit; Tsoar, Haim; Blumberg, Dan; Porat, Naomi

2014-05-01

402

An evaluation of the Rouse theory for sand transport in the Oka estuary, Spain  

NASA Astrophysics Data System (ADS)

The Rouse profile has been traditionally used to represent the vertical distribution of suspended sand in a marine benthic boundary layer. Yet it is one of the biggest unknowns in estuarine morphodynamics, largely due to uncertainties of the ratio of the sediment fall velocity to bed friction on which the Rouse exponent (R=ws/?ku*) is based. A field campaign was carried out at three different locations in the Oka estuary, northern Spain, in order to examine these uncertainties. Each location differed in grain size and flow condition thus offering a wide range of settings. The first survey was inside the estuary (wave sheltered, flood tide dominated and relatively broad estuary section), the second was at the distal ebb delta (ebb tide dominated and narrow estuary section), and the third was over the wave exposed proximal ebb delta (wave/flood tidal current combined flows and open sea). The aim of this study is to evaluate the applicability of the Rouse (1937) theory for the distribution of sand in suspension throughout a turbulent benthic boundary layer. A modified version of a Helley-Smith sampler was used to trap sand and measure the vertical distribution of sand in the water column. As well, a 1200 ADCP was used to measure flow velocity and backscatter together with an ADV (turbulence). The sand traps were found to have a sampling efficiency of 44%. The grain size at all stations was finer near the surface and coarser near the bed. The sand transport inside the estuary (Station 1) is inwards dominant. By contrast, the sand concentration during the ebb tide was ten times higher than during the flood tide at Station 2 and even higher at Station 3, which suggests that the sand transport over the ebb delta is seawards. The average Rouse parameters for Stations 1, 2, and 3 are 0.48±0.035, 0.78±0.23, and 0.46±0.06 respectively, which correspond to a coefficient of proportionality of the movability number, (?) of 4 (Van Rijn, 1993). These differ from previous findings of Villatoro et al. (2010) and Amos et al. (2010b).

Al-Ragum, A.; Monge-Ganuzas, M.; Amos, C. L.; Cearreta, A.; Townend, I.; Manca, E.

2014-04-01

403

Nitinol engine project test bed  

Microsoft Academic Search

A test bed engine was designed with the intent of reaching a 1 kilowatt size demonstration unit when operating as an engine. It can also be operated as a test bed driven by an electric motor for testing Nitinol elements. It was completed in December, 1974 and has since been operated in the test bed mode. Tests were run using

R. Banks; P. Hernandez; D. Norgren

1975-01-01

404

Bed load texture in an Alpine gravel bed river  

NASA Astrophysics Data System (ADS)

The spatial and temporal variations in bed load texture measured in a gravel bed river with a Helley-Smith sampler are compared with its bed material texture. Most measurements were undertaken at low excess shear stress, with low bed load discharge over an armored bed. Cross-sectionally averaged fractional bed load discharge increases with water discharge, but the explanation of the variance in fractional discharge is low (20-40%). Cross-sectional distribution of shear velocity explains in part the spatial variation in bed load texture. Because local hydraulic parameters are weak predictors of fractional bed load discharge for the granule-pebble range at nonequilibrium conditions, it reinforces the hypothesis that this size range, which comprises the bulk of bed load, derives from upstream sources. Temporal variations in the cross-sectional distribution of bed load texture are shown to depend on variations in bed topography and local shear stress. We demonstrate that the dominance of granule-pebble fractions is in part related to the hiding behavior of smaller fractions.

Habersack, Helmut M.; Laronne, Jonathan B.

2001-12-01

405

Investigating Sand on the Coast of Oregon and Washington.  

ERIC Educational Resources Information Center

Describes factors affecting sand composition and distribution along coastlines. Uses variations in sand types along the Oregon coast to illustrate the influences of sand grain density, wave action, and headlands on sand movements. Describes the seasonal movement of sand across beaches. (DLH)

Komar, Paul D.

2002-01-01

406

The importance of coastal sand dunes for terrestrial invertebrates in Wales and the UK, with particular reference to aculeate Hymenoptera (bees, wasps & ants)  

Microsoft Academic Search

Although most UK sand dune systems are now fossilized, with little mobility and reducing amounts of bare sand, they support\\u000a important populations and assemblages of terrestrial invertebrates. Offering open conditions, warm substrates and a range\\u000a of habitats and habitat structures, they have become increasingly significant as other coastal habitats have been lost. In\\u000a Wales, 680 Red Data Book and Nationally

M. A. Howe; G. T. Knight; C. Clee

2010-01-01

407

Solute dilution under imbibition and drainage conditions in a heterogeneous structure: Modeling of a sand tank experiment  

NASA Astrophysics Data System (ADS)

This study aims at modeling the transport of a conservative tracer in two dimensions, as experimentally observed in a strongly heterogeneous medium under conditions of variable water saturation during drainage and imbibition. Solute transport experiments were conducted in a sand tank containing an artificial packing of three quartz sands of different particle sizes. The packing was characterized by the presence of numerous homogeneous layers (0.5 × 5 × 5 cm) inclined at 45° and randomly distributed in a tank. Six different stationary flow conditions were sequentially established during imbibition and drainage. When a stationary flow regime was reached, several solute pulses were applied at different positions at the upper surface of the sand structure. The transport regime was studied by monitoring the tracer plumes injected as point-like pulses at the surface, as they travelled through the sand bedding. A textural map was generated from a digital image of the sand bedding. The Richards equation was solved with the experimental boundary conditions assuming homogeneity of the individual sand layers. The hydraulic properties of the three quartz sands were deduced from multistep-outflow column experiments [Ursino N, Gimmi T. Combined effect of heterogeneity, anisotropy and saturation on steady state flow and transport: structure recognition and numerical simulation. Water Resour Res 2004;40. doi:10.1029/2003WR002180]. The convection-dispersion equation was solved on the resulting flow fields for solute pulses of given solute mass applied onto the top boundary at the same positions as in the experiment. The simulated and observed solute concentration distributions were then compared. In agreement with the experimental observations, the simulations reproduced the existence of preferential pathways in those stationary flow fields at low saturation degrees. The values of the vertical and horizontal macroscopic dispersivities obtained from the simulations are smaller than experimentally observed, especially at low flow rates. The simulated solute concentration distributions show a realistic degree of solute dilution quantified as reactor ratio.

Rossi, M.; Ippisch, O.; Flühler, H.

2008-09-01

408

Large-eddy simulation of coupled turbulence, free surface, and sand wave evolution in an open channel  

NASA Astrophysics Data System (ADS)

We develop and validate a coupled 3D numerical model for carrying out three-phase large-eddy simulations of turbulence, free-surface, and sand waves-bed morphodynamics under live bed conditions. We employ the Fluid-Structure Interaction Curvilinear Immersed Boundary (FSI-CURVIB) method of Khosronejad et al. (Adv. in Water Res., 2011). The LES is implemented in the context of the CURVIB method using wall modeling (Kang and Sotiropoulos, Adv. in Water Res., 2011). Free-surface motion is simulated by coupling the CURVIB method with a two-phase level set approach as in Kang and Sotiropoulos (Adv. in Water Res., 2012). The mobile channel bed is discretized with an unstructured triangular grid and treated as the sharp-interface immersed boundary embedded in a background curvilinear mesh. Transport of bed load and suspended load sediments are combined in the non-equilibrium form of the Exner-Poyla for the bed surface elevation, which evolves due to the spatio-temporally varying bed shear stress field induced by the turbulent flow. Simulations are carried out for the rectangular flume experiments of Venditti et al. (2005). It is shown that the model can accurately capture sand-wave initiation, growth, and migration processes observed in the experiment. The simulated bed-forms are found to have amplitude and wave length scales of ~5 cm and ~30 cm, respectively. The effects of free-surface on bed-form dynamics is also quantified by comparing the three-phase simulation results with two-phase simulations using a fixed rigid-lid as the water surface.

Khosronejad, A.; Sotiropoulos, F.

2013-12-01

409

Pleistocene sand ramp deposits in the Aegean (Cyclades, Greece)  

NASA Astrophysics Data System (ADS)

Yellowish calcarenite is found abundantly on Despotiko, a small, unpopulated island in the central Aegean. Up to several meters thick layers of this sandstone is found as discordant cover above greenschist to amphibolite grade metamorphic rocks of the Attic-Cycladic Crystalline of the Central Hellenides. In some cases reddish soil is found below the sandstone. The calcarenite preferably fills preexisting relief of the underlying crystalline, therefore the thickest occurrences are found in the intermittent creeks. The sandstone can be traced from below sea-level up to around 90 m altitudes with abundant occurrences, but is most common at the north and northwest coast of the island. Generally, the sandstone layers and the internal lamination are parallel or at shallow angles to the slopes of the underlying crystalline without forming any morphological terraces. In some cases continuous layers of the sandstone can be traced for more than 20 m altitude. Cross-bedding has been observed in very rare cases and dips steeply towards the SE. The calcarenite (locally called "lithos poros") is strongly dominated by marine bioclasts (Corallinaceae, foraminifera, gastropod and bivalve fragments, etc.) with only minor siliciclastic components hardly exceeding 20%. The grains well-rounded and well-sorted with rain sizes range between medium sand to granule sizes. Based on the sandstone distribution in a high range of altitudes, sedimentary structures (e.g. pin-stripe lamination, high-angle cross bedding, rhizoliths, occurrence of terrestrial gastropod shells and correlation with almost identical sandstones in the Mediterranean) we conclude an aeolian origin and probably Pleistocene age of this sandstone. Horizons containing dm-sized, angular metamorphic clasts within well-rounded and well-sorted aeolian layers point to interaction of wind-blown and talus processes. Therefore these sediments are interpreted as sand ramps that formed during increased aeolian activity during the Pleistocene, compared to present conditions. Different settings are further supported by the scarcity, very small size, small grain size and dominance of siliciclastic grains of currently active sand dunes on Despotiko compared to the Pleistocene calcarenite.

Draganits, E.; Zuschin, M.; Gier, S.; Bickel, L.

2010-05-01

410

An Objective Approach for Defining Reference Bed Load Transport Rates in Gravel-Bed River  

NASA Astrophysics Data System (ADS)

Previous studies have described three phases of bed load transport in armored gravel-bed rivers, though any given river might not demonstrate all three phases. First, selective transport of the most easily mobilized grains over a largely immobile armor layer during low flows (Phase I, supply-limited transport of fine sediment and medium-sized particles of high protrusion and low friction angle). Second, partial transport of the armor layer as the flow increases (Phase II, transport-limited motion that depends on the spatial variation of both armoring and boundary shear stress, and thus the extent of the bed that can be mobilized). Finally, active transport of the majority of the armor layer at high discharge (Phase III, supply-limited transport, representing near-complete activation of the bed area and underlying sediment supply as modulated by the armor). Here, we use a piecewise regression similar to that of Ryan et al. [2002] for objectively identifying transitions between phases of bed load transport within a framework of dimensionless transport rate (W*) versus Shields stress (?*) [Parker et al., 1982]. The approach is applied to data sets from Oak Creek, Oregon, and the East Fork River, Wyoming, providing contrasting physical conditions and transport processes; Oak Creek is a well-armored gravel channel that exhibits Phase I and II transport, while the East Fork River is a poorly- armored, sand-gravel channel that exhibits Phase II and III transport. We find that phase transitions vary by size class and that equal mobility of a given size class (defined as pi/fi ~ 1, the proportion of a size class in the bed load relative to that of the subsurface [Wilcock and McArdell, 1993; Church and Hassan, 2002]) can occur during all phases of transport as the source and composition of the sediment supply change (i.e., mobilization of textural patches, banks, etc.) and as a numerical consequence of the degree of motion of other size classes. Our approach also provides a physical basis for defining size-specific reference transport rates (W*ri) at the transition from Phase I to II transport, and we test the performance of the Parker [1990] equation with this new definition of W*ri.

Barry, J. J.; Buffington, J. M.; Goodwin, P.; King, J. G.; Emmett, W. W.

2006-12-01

411

In Brief: Red tide Web site  

NASA Astrophysics Data System (ADS)

The U.S. National Oceanic and Atmospheric Administration has established the NOAA New England Red Tide Information Center to help people understand the significant red tides that are predicted to form there later this spring. The site (http://www.oceanservice.noaa.gov/redtide) will provide a summary of the current red tide situation and its potential harmful impacts on humans and animals and will serve as a central repository of information. The site also will have direct links to news releases, changes to relevant federal fishing regulations, links to closures of shellfish waters, and links to state agency Web sites with localized information. In addition, the site will have information about NOAA's scientific response effort as well as information from several other sources including NOAA's major response partner, the Woods Hole Oceanographic Institution (WHOI). On 24 April, WHOI scientists, using forecast models developed with NOAA funding support, predicted ``that excess winter precipitation has set the stage for a harmful algal bloom similar to the historic red tide of 2005.'' That bloom shut down shellfish beds from the Bay of Fundy to Martha's Vineyard for several months.

Showstack, Randy; Kumar, Mohi

2008-06-01

412

Iron-rich nanoparticles formed by aeolian abrasion of desert dune sand  

NASA Astrophysics Data System (ADS)

Iron-rich nanoparticles in aeolian mineral dust are of considerable importance to biogeochemical cycles. A major determinant of the chemical characteristics of nanoparticles is the parent sediment they are sourced from. The abrasion of dune sand has previously been shown to produce coarse dust (>1 ?m) during the occurrence of aeolian saltation. In this study, Australian red dune sands were laboratory abraded and emission of particles 18-414 nm was observed throughout the experiment duration (˜1 h). The mean size of particles was 130 nm at the start of the test, but this gradually decreased to 110 nm at the end. The number concentration of particles approximately trebled over the course of the experiment with results suggesting that collisions between mobile sand grains led to the production of new nanosized particles over time. Chemical analysis revealed that these nanoparticles were highly abundant in iron, with some aluminium present. This chemical composition suggests that nanoparticles are produced from the clay coatings surrounding the parent sand grains. The study shows that abrasion from saltation occurring in Australian dune sands can release iron-rich nanoparticles, making them available for downwind transport during blowing dust events.

Baddock, Matthew; Boskovic, Lucija; Strong, Craig; McTainsh, Grant; Bullard, Joanna; Agranovski, Igor; Cropp, Roger

2013-09-01

413

Cross-bedded limestone facies on San Salvador Island, Bahamas: New perspective on eolian calcarenites  

SciTech Connect

Limestones of eolian origin have been known from worldwide tropical regins since the early 1900s. On San Salvador Island, most of the exposed bed rock is Holocene and Pleistocene eolian calcarenite made of skeletal, peloidal, and oolitic fine to medium sand. The Pleistocene Grotto Beach Formation is composed of 50-90% ooids. An eolian interpretation for this interval is supported by paleosols, subaerial crusts, vadose cement, terrestrial fossils, karst features, associated reef and beach deposits, grainfall, sandflow, and climbing ripple strata, and shore-parallel sand bodies. Whole dune-forms are locally preserved; they were stabilized or frozen in place by early cementation and/or vegetation.

Caputo, M.V. (Mississippi State Univ. (USA))

1989-08-01

414

Sealing mechanism for cap beds of shallow-biogenic gas reservoirs in the Qiantang River incised valley, China  

NASA Astrophysics Data System (ADS)

Late Quaternary shallow-biogenic gas reservoirs are well-developed in the Qiantang River incised valley, eastern China. They present as sand bodies in the floodplain-estuary facies. Silty clay beds of floodplain-estuary facies and mud beds of estuarine-shallow marine facies serve as the direct and indirect cap beds, respectively, and the former has much better sealing ability. Capillary pressure sealing, pore water pressure sealing, and hydrocarbon concentration sealing contribute to the conservation of shallow-biogenic gas in the reservoirs, in which the pore water pressure sealing may be the most important factor.

Zhang, Xia; Lin, Chun-Ming; Li, Yan-Li; Qu, Chang-Wei; Wang, Shu-Jun

2013-10-01

415

The efficiency of vertical drains piercing flat-lying beds at Piedra del Aguila Dam  

SciTech Connect

This paper analyzes the problem of determining the pattern of flow to expect through a sequence of flat-lying beds of varying permeability which are pierced by a series of equally spaced vertical drains. A single permeable bed is assumed to be bounded by two impermeable beds from above and below and the influence of a reduction in screen efficiency is evaluated. This work arose from design work associated with the Piedra del Aguila hydroelectric project in Argentina in which the left abutment of the dam consisted of an ancient buried river channel filled with a sequence of sand and gravel sediments of varying clay content mixed with layers of volcanic tuff. The outcome of the study is that a practical limit of intercepting 80% of the flow is feasible and that this limit depends strongly upon the efficiency of the drains. All suspected aquifer beds must be drained and drain efficiency should be monitored over time.

Cogan, J. (PB/MK Team, Dallas, TX (United States))

1993-03-01