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1

Aeolian sands in continental red beds of the Middle Buntsandstein (Lower Triassic) at the western margin of the German Basin  

NASA Astrophysics Data System (ADS)

Aeolian sands occur widespread in continental red beds of the Middle Buntsandstein (Lower Triassic) at the western margin of the German Basin (Middle Europe), in the Eifel area. Cross-bedded sands were mainly deposited by grainfall on lee-slopes of barchanoid-type dunes in unimodal wind regime in both low-energy and high-energy environments. Occasionally, sets are internally truncated by reactivation surfaces. Crest height of solitary-set dunes varies in the range of some meters. Locally, sequences of cosets, both of tabular-planar and wedge-planar type, capped by flat or gently windward dipping topset beds, represent larger dune complexes of about 10-20 m in height and at least 80-100 m in lateral extent. Horizontal-laminated deposits originated as sand sheets in interdune areas. The dune sands were deposited by trade winds of the northern hemisphere in low palaeolatitude, predominantly by southeasterly and southwesterly trade winds in summer when the intertropical convergence zone was shifted to the north. Aeolian sands built up an extensive dune belt in the Eifel, intersected by braided to anastomosing rivers. Fluviatile incursions or heavy ephemeral rainfall led to aquatic redeposition of aeolian sediments and origin of shallow lakes in interdune depressions. Distribution of aeolian and fluviatile sediments in Karlstal-Schichten is different in the Southern, Western and Northern Eifel. Middle Buntsandstein sequence in the Southern Eifel reflects an evolution of the fluviatile depositional environment also incorporating the occurrence and distribution of aeolian sands. Evolution is characterized by increasing spacing and sinuosity of channels, weakening supply of coarse detritus from the source areas and decreasing braiding of the river systems. Aeolian sands occur in the final phase of this evolution which led from local alluvial fans via cobbly and pebbly braided rivers to sandy braided streams and finally to an intertonguing of aeolian dunes and braided to anastomosing rivers, matching with the climax of regional diversification of depositional milieu. The aeolian sand sea in the Eifel covered an area of nearly 2500 km 2 at the time of its largest extension. The dune belt ended in the Northern Eifel, the alternating sequence passed into an entirely alluvial succession which graded northwards by continuously diminishing grain size into the central playa/lacustrine to marine sediment series in Northwest Germany. Palaeogeography, sedimentology and genesis of the Middle Buntsandstein at the western margin of the Mid-European Basin and of Rotliegendes in Northwest Germany appear to be partially similar as is revealed by certain characteristics of the palaeogeographical reconstructions. Concurrence of Middle Buntsandstein palaeogeographical models for both Eifel and the whole German Basin most clearly delineates the key position of the Eifel for interpretation of the Buntsandstein sedimentary environment and the palaeogeography in Middle Europe.

Mader, Detlef

1982-04-01

2

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

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  

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

4

Channel bed evolution and sediment transport under declining sand inputs  

Microsoft Academic Search

Coupled field and laboratory investigations explore links between bed surface structure development and sediment transport as sand inputs decline. On the Pasig-Potrero River, we investigated channel recovery following emplacement of sand-rich pyroclastic deposits in the 1991 eruption of Mount Pinatubo, Philippines. As sediment inputs declined from 1996 to 2003, surface grain size increased, clast structures formed, and sediment mobility and

Karen B. Gran; David R. Montgomery; Diane G. Sutherland

2006-01-01

5

Effect of Bed Sand Content on the Turbulent Flows Associated with Clusters on an  

E-print Network

Effect of Bed Sand Content on the Turbulent Flows Associated with Clusters on an Armored Gravel Bed often develops clusters as part of its structure. The influence of sand on armoring and the impact created from four different sediments, which progressively increased from 1­38% sand in the bed sediment

Curran, Joanna C.

6

Effect of Sand Supply on Transport Rates in a Gravel-Bed Channel  

E-print Network

Effect of Sand Supply on Transport Rates in a Gravel-Bed Channel Joanna C. Curran, A.M.ASCE,1 depth, and gravel feed rate, sand feed rates were varied from 0.16 to 6.1 times that of gravel. The bed slope decreased with increasing sand supply, indicating that the gravel could be transported at the same

Curran, Joanna C.

7

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

PubMed

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 is suitable for using in farms where land is limited. The average COD and nitrogen loading rate of the vegetated vertical flow bed were 105 g/m2 x d and 11 g/m2 x d respectively. The wastewater was fed intermittently at intervals of 4 hours with a hydraulic loading rate of 3.7 cm/d. The recirculation of the effluent increased total nitrogen (TN) removal efficiency from 71% to 85%. The chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN) removal efficiencies were 95% and 98%. Nitrification was significant in vertical flow Cyperus bed, and the concentration of nitrate increased by a factor of 140. The horizontal flow sand bed enhanced COD removal and nitrate reduction was 60%. Plant uptake of nitrogen was 1.1 g N/m2 x d or dry biomass production was 2.8 kg/m2 over 100 days. PMID:11804085

Kantawanichkul, S; Neamkam, P; Shutes, R B

2001-01-01

8

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

E-print Network

river Sand-bed Channel characteristics Great Plains Hydraulic geometry Downstream trends in hydraulic 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

Gido, Keith B.

9

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

NASA Astrophysics Data System (ADS)

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

2014-03-01

10

Density stratification effects in sand-bed rivers  

USGS Publications Warehouse

In this paper the effects of density stratification in sand-bed rivers are studied by the application of a model of vertical velocity and concentration profiles, coupled through the use of a turbulence closure that retains the buoyancy terms. By making the governing equations dimensionless, it is revealed that the slope is the additional dimensionless parameter introduced by inclusion of the buoyancy terms. The primary new finding is that in general density stratification effects tend to be greater in large, low-slope rivers than in their smaller, steeper brethren. Under high flow conditions the total suspended load and size distribution of suspended sediment can be significantly affected by density stratification, and should be accounted for in any general theory of suspended transport. ?? ASCE.

Wright, S.; Parker, G.

2004-01-01

11

Continental Shelf Research 22 (2002) 19872000 The accumulation and decay of near-bed suspended sand  

E-print Network

sand concentration due to waves and wave groups Christopher E. Vincenta, *, Daniel M. Hanesb a School were made of suspended sand and bedform dimensions caused by prototype- scale waves, both regular and in groups, over a mobile sand bed, in a very large wave channel. The changes in wave height at the beginning

Kirby, James T.

12

Enhanced In Situ Bioremediation of Phenol in Bioestimulated Unsaturated and Saturated Sand-Bed Columns  

Microsoft Academic Search

Biodegradation of phenol was observed in unsaturated sand- bed columns, in which phenol concentration declined from 298 mg phenol\\/kg sand to less than 1 mg\\/kg after 21 days. In saturated sand-bed columns, phenol concentration declined from 230 mg phenol\\/kg to less than 1 mg\\/kg after 37 days. Pseudo-first-order phenol biodegradation rates were in the range 0.25 days21 (R2 5 0.9)

Blanca Antizar-Ladislao; Noah I. Galil

13

The importance of bed sediment sand content for the structure of a static armor layer in a gravel bed river  

NASA Astrophysics Data System (ADS)

surface structure of static armor layers generated from water-worked gravel bed channels was investigated with primary focus on the influence of sand content and flow rate. Flume experiments were conducted in which four sediment mixtures with sand contents between 1% and 38% were armored under one of three different flow rates. First- and second-order statistical analyses were applied to digital elevation models of unarmored, armored, and clustered bed surface areas to identify changes in surface structure. Results were combined with data from previous research to create an extended data set of armored bed surfaces. Water-worked, unarmored bed surfaces established under a dynamic equilibrium flow rate impacted the topographic variability and structure of the armored beds. Surface complexity decreased with armor formation as surface grains preferentially aligned with the flow direction. The bed surface became smoother, and where sediment mixture sand content was constant, there was greater smoothing of the surface during higher armoring flows as grains rearranged more easily. As bulk sand content increased, statistical analyses of the expanded data set showed that beds with very little sand content developed static armor layers that remained rough and had greater topographic variability than armor layers from sediments with higher sand contents. The bulk sediment sand content exerted a stronger influence over the change in surface roughness and structure upon armoring than that of the flow rate during armor formation. When combined with the knowledge of the local flow regime, the sand content may aid in predictions related to armored bed surface structure.

Curran, Joanna Crowe; Waters, Kevin A.

2014-07-01

14

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

15

Algorithm for resistance to flow and transport in sand-bed channels  

USGS Publications Warehouse

An algorithm is developed that relates depth to discharge and determines bed- and suspended-load transport for the entire range of bed forms found in sand-bed channels; equilibrium-state geometry of lower flow regime bedforms is also predicted. A Meyer-Peter-type formulation is used to compute sand transport in the bed-load layer and for computing suspended sand transport, McLean's procedure is adopted. A bed-form classifcation scheme is developed. The algorithm produces overall geometric averages of predicted to observed depth and predicted to observed transport of 1.00. For a verification data set of 855 observations, mostly from rivers and canals, the overall geometric averages of predicted to observed depth and transport are 0.87 and 1.14. -from Author

Bennett, J.P.

1995-01-01

16

Phenol degradation in a three-phase biofilm fluidized sand bed reactor  

Microsoft Academic Search

A previous three phase fluidized sand bed reactor design was improved by adding a draft tube to improve fluidization and submerged effluent tubes for sand separation. The changes had little influence on the oxygen transfer coefficients(KL a), but greatly reduced the aeration rate required for sand suspension. The resulting 12.5 dm3 reactor was operated with 1 h liquid residence time,

M. Etzensperger; S. Thoma; S. Petrozzi; I. J. Dunn

1989-01-01

17

Dominance of Changes in Bed-Sand Grain Size Over Bed-Sand Area in Regulating Suspended-Sand Concentration: Examples From the Colorado River  

Microsoft Academic Search

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 suspended-sand concentration, (2) hysteresis in suspended-sand grain size coupled to the hysteresis in suspended-sand concentration, (3) production

D. J. Topping; D. M. Rubin; S. A. Wright; T. S. Melis

2007-01-01

18

Scaling laws in aeolian sand transport: Erodible versus non-erodible bed  

NASA Astrophysics Data System (ADS)

We investigated via wind-tunnel experiments the role of the boundary conditions at the bed in the aeolian sand transport. We analyzed two different bed configurations: one with a sandy erodible bed and the other with a non-erodible bed. By using Particle Tracking Velocimetry technique (PTV), we characterized the saltation layer in both configurations and evidenced contrasting features. We show in particular that over an erodible bed the particle velocity in the saltation layer and the saltation length are almost invariant with the wind strength, whereas over a non-erodible bed these quantities vary significantly with the air friction speed. It results that the particle transport rate over an erodible bed does not exhibit a cubic dependence with the air friction speed, as predicted by Bagnold, but a quadratic one. This contrasts with saltation over nonerodible bed where the cubic Bagnold scaling holds. Our findings emphasize the crucial role of the boundary conditions at the bed and may have important practical consequences for aeolian sand transport in natural environment.

Valance, A.; Ho, T. D.; Moctar, A. Ould El; Dupont, P.

2013-06-01

19

Suspension and near-bed load sediment transport processes above a migrating, sand-rippled bed under shoaling waves  

NASA Astrophysics Data System (ADS)

The present study focuses on the fine-scale flow and sand transport processes above onshore migrating ripples below skewed surface gravity waves in the shoaling zone. A set of acoustic instruments was deployed in the shoaling region of the large-scale wave channel at Canal d'Investigacío i Experimatacío Marítima, Universitat Poltiècnica de Catalunya, Barcelona, Spain, in order to provide high-resolution velocity and sediment concentration profiles with an acoustic concentration and velocity profiler (ACVP). Measurements are analyzed relative to the positions of the measured nonmoving sand bed and the interface separating the suspension from the near-bed load layer. This interface is detected here by the application of a novel acoustic bed echo detection method. Furthermore, the use of the dual-frequency inversion proposed in the work of Hurther et al. (2011) allows for the calculation of the sediment concentration profile across both the suspension and near-bed load layers. The sand bed was covered by quasi-two-dimensional suborbital ripples migrating onshore. As proposed by O'Donoghue et al. (2006), the occurrence of quasi-two-dimensional ripples is attributed to the fine-size sand of D50 = 250 ?m used in the present study under full-scale forcing conditions. In order to determine the effect of shoaled wave skewness on the ripple vortex entrainment and sediment transport, the instantaneous and mean measurements of the flow, sediment concentration, and sediment flux along the ripple profile are discussed in terms of (1) the occurrence of ripple vortex entrainment on either side of the ripple crest; (2) the wave velocity phase lagging driven by the ripple vortex entrainment process and the turbulent bed friction effects in the wave boundary layer; (3) phase lagging between velocity and maximum concentration and sediment flux events; (4) the structure of bed friction and ripple-driven turbulence across the suspension and the near-bed load layers; and (5) the streaming components. The results on these aspects strongly support that the wave velocity skewness effect under shoaling waves is fairly similar to the one obtained in skewed oscillatory water tunnel flows. Furthermore, it is found that the onshore-oriented net bed load sediment transport is at the origin of the onshore ripple migration. This flux is roughly twice as much as the opposite offshore-oriented net suspension flux dominated by the ripple vortex entrainment processes.

Hurther, D.; Thorne, Peter D.

2011-07-01

20

Reynolds averaged theory of turbulent shear flows over undulating beds and formation of sand waves.  

PubMed

Based on the Reynolds averaged Navier-Stokes (RANS) equations and the time-averaged continuity equation, a theory of turbulent shear flow over an undulating sand bed is developed addressing the instability criterion of plane sand beds in free-surface flows leading to the formation of sand waves. In the analysis, the integration of RANS equations leads to generalized Saint Venant equations, in which the time-averaged streamwise velocity is characterized by a power law obtained from turbulence closure, treating the curvilinear streamlines by the Boussinesq approximation. As a consequence, the modified pressure distribution has a departure from the traditionally linear hydrostatic pressure distribution. The instability analysis of a plane sand bed yields the curves of the Froude number versus nondimensional wave number, determining an instability zone for which at lower Froude numbers (less than 0.8), the plane bed becomes unstable with the formation of dunes; whereas at higher Froude numbers, the plane bed becomes unstable with the formation of standing waves and antidunes. For higher Froude numbers, the experimental data for antidunes lie within the unstable zone; while for lower Froude numbers, the same is found for dunes with some experimental scatter. PMID:19905209

Bose, Sujit K; Dey, Subhasish

2009-09-01

21

Sand Transport, Flow Turbulence, and Bed Forms over an Immobile Gravel Bed  

Technology Transfer Automated Retrieval System (TEKTRAN)

Channels downstream of dams often become armored because the sediment supply from upstream is cut off. Sand is generally supplied to these armored reaches intermittently from tributaries downstream of the dam or from sand bypassing. Accurate predictions of the rate of transport of sand over and th...

22

Flow and sand transport over an immobile gravel bed.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many dams in the USA and elsewhere have exceeded their design life and are being considered for remediation or removal, which will result in the reintroduction of fine sediments, often into coarse grained armored substrates, downstream of dams. The deposition of sand in the interstices of the grave...

23

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

24

Large-scale laboratory experiment on erosion of sand beds by moving circular vertical jets  

Microsoft Academic Search

This study investigates the topographic deformation due to the erosion of a sand bed impinged by a moving submerged turbulent round jet in a large-scale laboratory. The test conditions represent the case of discharges beneath a vessel while operating in water with a limited clearance such as a shallow navigation channel. The jet moves horizontally and discharges water vertically downward

Po-Hung Yeh; Kuang-An Chang; John Henriksen; Billy Edge; Peter Chang; Andrew Silver; Abel Vargas

2009-01-01

25

Scaling laws in aeolian sand transport: Erodible versus Non-erodible bed  

E-print Network

friction speed. It results that the particle transport rate over an erodible bed does not exhibit a cubic- ing transport rates are identical as soon as no sand is deposited within the tunnel. Thus, given to sustain the imposed transport rate and deposition

Paris-Sud XI, Université de

26

Morphodynamics of small-scale superimposed sand waves over migrating dune bed forms  

E-print Network

Morphodynamics of small-scale superimposed sand waves over migrating dune bed forms Jeremy G migrating dunes are examined using data drawn from laboratory experiments. We refer to the superimposed classified as ripples, dunes, or bars. Within the experiments, the sheets formed downstream

Venditti, Jeremy G.

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

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, P. J., III; Corson, I.C.

2000-01-01

29

The Unified Gravel-Sand (TUGS) Model: Simulating Sediment Transport and Gravel/Sand Grain Size Distributions in Gravel-Bedded Rivers  

NASA Astrophysics Data System (ADS)

This paper presents The Unified Gravel-Sand (TUGS) model that simulates the transport, erosion, and deposition of both gravel and sand. TUGS model employs the surface-based bed load equation of Wilcock and Crowe (2003) and links grain size distributions in the bed load, surface layer, and subsurface with the gravel transfer function of Hoey and Ferguson (1994) and Toro-Escobar et al. (1996), a hypothetical sand transfer function, and hypothetical functions for sand entrainment/infiltration from/into the subsurface. The model is capable of exploring the dynamics of grain size distributions, including the fractions of sand in sediment deposits and on the channel bed surface, and is potentially useful in exploring gravel-sand transitions and reservoir sedimentation processes. Simulation of three sets of large-scale flume experiments indicates that the model, with minor adjustment to the Wilcock-Crowe equation, excellently reproduced bed profile and grain size distributions of the sediment deposits, including the fractions of sand within the deposits. Simulation of a flushing flow experiment indicated that the sand entrainment function is potentially capable of simulating the short-term processes such as flushing flow events.

Cui, Yantao

2007-10-01

30

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  

Microsoft Academic Search

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

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

2007-01-01

31

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

32

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

33

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

34

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

35

Flow refugia for the zoobenthos of a sand-bed river: the role of physical-habitat complexity  

E-print Network

by hydrologic fluctuations. We worked on and around sandbars in the Kansas River (Kaw), a multithread, sand, Chironomidae, community structure, disturbance, flow pulses, Kansas River, midges. Hydrologic cycles haveFlow refugia for the zoobenthos of a sand-bed river: the role of physical-habitat complexity Brian

Thorp, James H.

36

Iron oxide mineralogy in late Miocene red beds from La Gloria, Spain: rock-magnetic,  

E-print Network

Iron oxide mineralogy in late Miocene red beds from La Gloria, Spain: rock-magnetic, voltammetric March 2002; accepted 20 January 2003 Abstract Free ferric oxides of a red bed series were analyzed constituents. Free Fe oxides occurred at a concentration of 0.3­2.1%, i.e. in the majority of the samples below

Utrecht, Universiteit

37

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

38

True in-situ bed preparation: oil shale and tar sand  

SciTech Connect

In 1978, a detailed study was conducted to evaluate the status of the bed preparation technology that had been developed for true in-situ processing of oil shale. It was concluded that the two techniques which had received the bulk of the attention in prior field experimentation, namely the wellbore springing and hydraulic/explosive fracturing concepts, both had inherent traits which would prevent them from being useful in practical applications. In the current paper, the previous results are reviewed to determine whether or not they are also applicable to tar sand. The conclusion reached is that neither technique would be practical for preparing a tar sands deposit for in-situ processing.

Boade, R. R.

1980-01-01

39

Effects of fruit bagging on coloring and related physiology, and qualities of red Chinese sand pears during fruit maturation  

Microsoft Academic Search

Red Chinese sand pears (Pyrus pyrifolia Nakai) are particular to China. In order to determine the effects of fruit bagging treatments (including bag types, bag removal patterns and dates) on fruit qualities and to understand the mechanism of coloring of red Chinese sand pears, two experiments were carried out. In the first experiment, fruit of ‘Meirensu’ were firstly covered by

Chunhui Huang; Bo Yu; Yuanwen Teng; Jun Su; Qun Shu; Zaiquan Cheng; Liqiong Zeng

2009-01-01

40

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

41

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

42

Upper Pleistocene turbidite sand beds and chaotic silt beds in the channelized, distal, outer-fan lobes of the Mississippi fan  

SciTech Connect

Cores from a Mississippi outer-fan depositional lobe demonstrate that sublobes at the distal edge contain a complex local network of channelized-turbidite beds of graded sand and debris-flow beds of chaotic silt. Off-lobe basin plains lack siliciclastic coarse-grained beds. The basin-plain mud facies exhibit low acoustic backscatter on SeaMARC IA sidescan sonar images, whereas high acoustic backscatter is characteristic of the lobe sand and silt facies. The depth of the first sand-silt layer correlates with relative backscatter intensity and stratigraphic age of the distal sublobes (i.e., shallowest sand = highest backscatter and youngest sublobe). The high proportion (> 50%) of chaotic silt compared to graded sand in the distal, outer-fan sublobes may be related to the unstable, muddy, canyon-wall source areas of the extensive Mississippi delta-fed basin slope. A predominance of chaotic silt in cores or outcrops from outer-fan lobes thus may predict similar settings for ancient fans.

Nelson, C.H.; Lee, H.L. (Geological Survey, Menlo Park, CA (United States)); Twichell, D.C.; Schwab, W.C. (Geological Survey, Woods Hole, MA (United States)); Kenyon, N.H. (Inst. of Oceanographic Sciences, Wormley, Surrey (United Kingdom))

1992-08-01

43

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

44

Using spatial and temporal changes in bed-sediment grain size to trace sand transport: results of 30,000 bed-sediment grain-size measurements from Grand Canyon between 2000 and 2008  

Microsoft Academic Search

Previous work has shown that grain size of sand on the riverbed is as important as flow in regulating sand transport in the Colorado River in Grand Canyon (Rubin and Topping, 2001). Because traditional field techniques are inadequate for repeatedly mapping grain size on the bed, an underwater microscope and digital imaging software were developed for in-situ analysis of bed-sediment

D. M. Rubin; D. J. Topping; H. Chezar; J. E. Hazel; M. A. Kaplinski; M. J. Breedlove; T. S. Melis; J. C. Schmidt

2008-01-01

45

An extended DEM–CFD model for char combustion in a bubbling fluidized bed combustor of inert sand  

Microsoft Academic Search

This paper proposes a transient three-phase numerical model for the simulation of multiphase flow, heat and mass transfer and combustion in a bubbling fluidized bed of inert sand. The gas phase is treated as a continuum and solved using the computational fluid dynamics (CFD) approach; the solid particles are treated as two discrete phases with different reactivity characteristics and solved

Yongming Geng; Defu Che

2011-01-01

46

Ecological Responses to Hydrogeomorphic Fluctuations in a Sand Bed Prairie River: River Complexity, Habitat Availability, and Benthic Invertebrates  

E-print Network

Ecological Responses to Hydrogeomorphic Fluctuations in a Sand Bed Prairie River: River Complexity, Habitat Availability, and Benthic Invertebrates By Brian J. O’Neill Submitted to the graduate degree program in Ecology and Evolutionary..., Habitat Availability, and Benthic Invertebrates Committee: _____________________________ Chairperson Date Approved_____________________ 3 Abstract Rivers...

O'Neill, Brian James

2010-04-02

47

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

48

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

49

New England Shellfish Beds Reopen After Toxic Red Algae Recedes  

NSDL National Science Digital Library

This PBS article describes red tide, a phenomenon caused by phytoplankton in coastal waters. The site includes brief summaries of the causes and impacts of red tide, both on health and the tourism industry. A link to a PDF version of the article is provided.

Annie Schleicher

50

[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

51

Paleomagnetism of Cretaceous red beds from Tadzhikistan and Cenozoic deformation due to India-Eurasia collision  

Microsoft Academic Search

We have carried out structural and paleomagnetic studies in the Tadzhik depression in order to evaluate the main features of the Alpine tectonics of this area. About 340 cores from 43 sites of Lower Cretaceous red beds were sampled from four different localities in the basin and adjacent ranges. A well-defined component of magnetization (A) of normal polarity with high

Mikhail L. Bazhenov; Herve Perroud; Annick Chauvin; Valentin S. Burtman; Jean-Charles Thomas

1994-01-01

52

The red bed controversy revisited: shape analysis of Colorado Plateau units suggests long magnetization times  

E-print Network

is acquired in clastic sedimentary rocks merits further study. D 2002 Elsevier Science B.V. All rights(es) of acquisition of remanent mag- netization in sedimentary rocks, particularly red beds (for examples of opposing in the sedimentary rocks they studied was a relatively rapid detrital process, and thus that remanence

Housen, Bernie

53

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

54

Red algal beds increase the condition of nekto-benthic fish  

NASA Astrophysics Data System (ADS)

The present study analysed the effect of three different benthic habitats, the maërl, Peyssonnelia red algal beds and sandy bottoms, on the condition of two nekto-benthic fish species: Serranus cabrilla and Trigloporus lastoviza. Sampling was conducted during the MEDITS 2010 and 2011 surveys around the Balearic Islands. The condition of the spawning females of both species was determined by using i) biochemical measurements of proteins and lipids in the muscle, liver and gonads, and ii) weight at length relationships based on eviscerated, liver, and gonad weights. Moreover, based on the total weight at length relationship, the mean somatic condition (SC) of the sexually inactive individuals of S. cabrilla and males of T. lastoviza was calculated. Lipid reserves were higher in the livers of S. cabrilla and T. lastoviza from the maërl beds. Additionally, S. cabrilla showed higher lipid reserves in the gonads both in the maërl and Peyssonnelia beds. The mean weights of the liver and gonads at a given individual length revealed the same pattern as the lipids, whereas the mean eviscerated weight was higher in the maërl beds but only for S. cabrilla. A positive correlation was detected between the SC and the biomass of the algal species characterizing the maërl beds for both S. cabrilla and T. lastoviza. The high habitat quality of the red algal beds off the Balearic Islands increased the condition of nekto-benthic fish. In oligotrophic areas, such as the archipelago, these 'oases' could help fish to maintain healthy populations.

Ordines, Francesc; Bauzá, Marco; Sbert, Miquel; Roca, Pilar; Gianotti, Magdalena; Massutí, Enric

2015-01-01

55

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

56

Synthesis and characterization of black, red and yellow nanoparticles pigments from the iron sand  

NASA Astrophysics Data System (ADS)

The aim of this research is to synthesize nanoparticles of black pigment of Magnetite (Fe3O4), red pigment of hematite (?-Fe2O3), and yellow pigment of ghoetite (?-FeOOH) from the iron sand. The black pigment of Fe3O4 and the yellow pigment ?-FeOOH nanoparticles were synthesized by coprecipitation method with variation of pH. Whereas, the red pigment Fe2O3 was sythesized by sintering Fe3O4 nanoparticles at temperature between 400 °C and 700 7°C for 1 hour. All the pigments has been characterized using X-ray diffraction and SEM. The XRD results shown that the particle size of the black pigmen Fe3O4, red pigment Fe3O4 and yellow pigment ?-FeOOH are around 12, 32, and 30 nm repectively. The particle size of Fe2O3 nanoparticles increase by increasing sintering temperature from 32 nm at 400 °C to 39 nm at 700 °C. For yellow pigment of ?-FeOOH, the particle size increase by increasing pH from 30,54 nm at pH 4 to 48,60 nm at pH 7. The SEM results shown that the morphologies of black, yellow and red pigments are aglomarated.

Mufti, Nandang; Atma, T.; Fuad, A.; Sutadji, E.

2014-09-01

57

Evaluating the potential for remote bathymetric mapping of a turbid, sand-bed river: 1. Field spectroscopy and radiative transfer modeling  

Microsoft Academic Search

Remote sensing offers an efficient means of mapping bathymetry in river systems, but this approach has been applied primarily to clear-flowing, gravel bed streams. This study used field spectroscopy and radiative transfer modeling to assess the feasibility of spectrally based depth retrieval in a sand-bed river with a higher suspended sediment concentration (SSC) and greater water turbidity. Attenuation of light

Carl J. Legleiter; Paul J. Kinzel; Brandon T. Overstreet

2011-01-01

58

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

59

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

60

Spatial patterns of scour and fill in dryland sand bed streams 1843  

Technology Transfer Automated Retrieval System (TEKTRAN)

Spatial patterns of scour and fill in two dryland ephemeral stream channels with sandy bed material have been measured with dense arrays of scour chains. Although the depth and areal extent of bed activity increased with discharge, active bed reworking at particular locations within the reaches res...

61

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

62

Evaluating the potential for remote bathymetric mapping of a turbid, sand-bed river: 1. Field spectroscopy and radiative transfer modeling  

USGS Publications Warehouse

Remote sensing offers an efficient means of mapping bathymetry in river systems, but this approach has been applied primarily to clear-flowing, gravel bed streams. This study used field spectroscopy and radiative transfer modeling to assess the feasibility of spectrally based depth retrieval in a sand-bed river with a higher suspended sediment concentration (SSC) and greater water turbidity. Attenuation of light within the water column was characterized by measuring the amount of downwelling radiant energy at different depths and calculating a diffuse attenuation coefficient, Kd. Attenuation was strongest in blue and near-infrared bands due to scattering by suspended sediment and absorption by water, respectively. Even for red wavelengths with the lowest values of Kd, only a small fraction of the incident light propagated to the bed, restricting the range of depths amenable to remote sensing. Spectra recorded above the water surface were used to establish a strong, linear relationship (R2 = 0.949) between flow depth and a simple band ratio; even under moderately turbid conditions, depth remained the primary control on reflectance. Constraints on depth retrieval were examined via numerical modeling of radiative transfer within the atmosphere and water column. SSC and sensor radiometric resolution limited both the maximum detectable depth and the precision of image-derived depth estimates. Thus, although field spectra indicated that the bathymetry of turbid channels could be remotely mapped, model results implied that depth retrieval in sediment-laden rivers would be limited to shallow depths (on the order of 0.5 m) and subject to a significant degree of uncertainty. ?? 2011 by the American Geophysical Union.

Legleiter, C.J.; Kinzel, P.J.; Overstreet, B.T.

2011-01-01

63

Evaluating the potential for remote bathymetric mapping of a turbid, sand-bed river: 1. field spectroscopy and radiative transfer modeling  

USGS Publications Warehouse

Remote sensing offers an efficient means of mapping bathymetry in river systems, but this approach has been applied primarily to clear-flowing, gravel bed streams. This study used field spectroscopy and radiative transfer modeling to assess the feasibility of spectrally based depth retrieval in a sand-bed river with a higher suspended sediment concentration (SSC) and greater water turbidity. Attenuation of light within the water column was characterized by measuring the amount of downwelling radiant energy at different depths and calculating a diffuse attenuation coefficient, Kd. Attenuation was strongest in blue and near-infrared bands due to scattering by suspended sediment and absorption by water, respectively. Even for red wavelengths with the lowest values of Kd, only a small fraction of the incident light propagated to the bed, restricting the range of depths amenable to remote sensing. Spectra recorded above the water surface were used to establish a strong, linear relationship (R2 = 0.949) between flow depth and a simple band ratio; even under moderately turbid conditions, depth remained the primary control on reflectance. Constraints on depth retrieval were examined via numerical modeling of radiative transfer within the atmosphere and water column. SSC and sensor radiometric resolution limited both the maximum detectable depth and the precision of image-derived depth estimates. Thus, although field spectra indicated that the bathymetry of turbid channels could be remotely mapped, model results implied that depth retrieval in sediment-laden rivers would be limited to shallow depths (on the order of 0.5 m) and subject to a significant degree of uncertainty.

Legleiter, Carl J.; Kinzel, Paul J.; Overstreet, Brandon T.

2011-01-01

64

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

65

A comparison of detailed equatorial red bed records of secular variation during the Permo-Carboniferous Reversed Superchron  

Microsoft Academic Search

Detailed secular variation records during a superchron may provide information on the behaviour of the geodynamo during periods that the field does not reverse. The Permian red beds in Dôme de Barrot (southern France)-deposited during the Permo-Carboniferous Reversed Superchron (PCRS, 317-265 Ma) -were previously argued to accurately record palaeosecular variation (PSV). This result is particularly valuable because the red beds

Marcela M. Haldan; Cor G. Langereis; Andrew J. Biggin; Mark J. Dekkers; Michael E. Evans

2009-01-01

66

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

Technology Transfer Automated Retrieval System (TEKTRAN)

The factors controlling the complex interaction of a coarse stream bed 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 ...

67

Tectonic rotations south of the Bohemian Massif from palaeomagnetic directions of Permian red beds in Hungary  

USGS Publications Warehouse

Palaeomagnetic studies were carried out in Permian red beds of the Balaton Highlands, the Mecsek Mountains and the Bu??kk Mountains of Hungary. Statistically well defined directions were obtained from six localities in the Balaton Highlands and two localities in the Mecsek Mountains. No meaningful results were obtained from the Bu??kk Mountains. Three magnetic components were identified from red beds of the Balaton Highlands: (1) in haematite with a very high unblocking temperature (700??C), interpreted as a Permian magnetization (Dc= 79??, Ic=-11??, k = 24, ??95 = 13.6 ??), in six samples from three beds in a single locality (2) a secondary but ancient component residing mainly inmaghemite (D = 314??, I = 49??, k = 48, ??95 = 10.0??), in 84 samples from six localities with a within-locality scatter increasing on unfolding; and (3) a direction parallel to the present field (D = 7??, I = 62??, k = 46, ??95 = 7.7 ??), in nine samples from a single locality. For the Balaton Highlands, the component 1 direction agrees with directions obtained from Permian red beds and volcanics in the eastern part of the Southern and Eastern Alps and the Inner West Carpathians. All show large, apparent rotations relative to stable Europe since the Permian. Component 2 is of post-folding (post-Aptian) age. Its direction agrees with known Late Cretaceous directions from the Transdanubian Central Mountains, which also show significant counterclockwise rotation relative to stable Europe. The characteristic magnetization for the Mecsek Mountains resides in haematite and may be primary. The directions indicate only a slight net counterclockwise rotation of the Mecsek Mountains with respect to stable Europe since the Permian. ?? 1987.

Marton, E.; Elston, D.P.

1987-01-01

68

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

69

Responses of red-osier dogwood to oil sands tailings treated with gypsum or alum.  

PubMed

The application of composite or consolidated tailings (CT) technology provides Alberta's oil sands industry with a means of reducing the volume of the fines fraction in extraction tailings and allows for faster reclamation and revegetation of mining sites. This study examined the effects of coagulant aids (gypsum and alum), used in the production of CT, on the ion content, growth, and survival of greenhouse-grown red-osier dogwood (Cornus sericea L. subsp. sericea). Seedlings were planted in gypsum-CT and alum-CT substrates, and compared with those planted in reclamation material (salvaged peat and till). The seedlings were bottom-watered with one of the following: (i) Hoagland mineral solution prepared in deionized water (Epstein, 1972); (ii) Hoagland solution in gypsum-based CT release water; or (iii) Hoagland solution in alum-based CT release water. Pore water of CT substrates and CT release waters had similar chemical characteristics, including salinity levels. However, plants in CT substrates had higher concentrations of ions (particularly Na and B), reduced growth, and higher mortality than plants in reclamation material and treated with CT waters. The presence of H2S indicated low-oxygen conditions in the CT substrates, while in the reclamation materials with CT release water treatments, no evidence of sulfides was observed. Low-oxygen conditions in the CT substrate treatments may have interfered with plant exclusion mechanisms for Na and B. Therefore, substrate properties may modify responses of reclamation plants to pore water chemistry due to the effects on oxygen availability to roots. PMID:12809301

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

2003-01-01

70

Paleomagnetism and Magnetic Anisotropy of Neogene Red Beds from Tarim Basin, NW China  

NASA Astrophysics Data System (ADS)

Greater than 1000 km of continental shortening north of the Tarim basin has been derived from Cretaceous and Tertiary paleomagnetic data. Recent studies have shown that much of the continental shortening derived from Cretaceous results can be due to inclination error caused by deposition and compaction processes. To better understand the Tertiary paleomagnetic data from the Tarim basin, we conducted a combined paleomagnetic and magnetic anisotropy study for the Neogene red beds from the south Tianshan frontal thrust belt, north Tarim basin. A total of 11 sites of paleomagnetic cores were collected from the Neogene Kangcun Formation, and 81 samples were treated with progressive thermal demagnetization. A characteristic remanent magnetization (ChRM) was isolated at temperatures between 300 and 690°C from 9 sites. The mean ChRM direction, Dg =180.3°, Ig = -55.9°, kg = 5.5, ?95 =22.6°, in situ, and Ds = 177.7°, Is = -38.5°, ks = 15.5, ?95 = 14.4°, in stratigraphic coordinates, passes the McFadden (1990) fold test at 99% confidence level. Compared with the reference pole of Besse and Courtillot (2002), this direction implies about 23° of inclination shallowing. Anisotropy of magnetic susceptibility (AMS) reveals a triaxial, oblate fabric with foliation between 1.03 and 1.16, and minimum axis perpendicular to bedding. Each of the three axes of anisotropy ellipsoid passes the fold tests, indicating depositional and/or compaction fabrics. Measurement of high temperature component of isothermal remanent magnetization acquired in the bedding parallel and bedding perpendicular directions yielded anisotropy between 1.00 and 1.18. The remanent anisotropy shows a good relationship with paleomagnetic inclination. Linear and exponential fits yielded corrected inclinations of 56° and 57°, respectively, about 18° of inclination correction. The remaining inclination difference, 5°, can be explained by crustal shortening in Tianshan ranges.

Tan, X.; Kodama, K. P.; Chen, H.; Fang, D.; Sun, D.; Li, Y.

2009-12-01

71

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

72

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

73

Volcanic red-bed copper mineralisation related to submarine basalt alteration, Mont Alexandre, Quebec Appalachians, Canada  

NASA Astrophysics Data System (ADS)

Two types of native copper occur in Upper Silurian basaltic rocks in the Mont Alexandre area, Quebec Appalachians: (1) type 1 forms micrometric inclusions in plagioclase and is possibly magmatic in origin, whereas (2) type 2 occurs as coarse-grained patches rimmed by cuprite in altered porphyritic basalt. Type 1 has higher contents of sulphur (2,000-20,263 ppm) and arsenic (146-6,017 ppm), and a broader range of silver abundances (<65-2,186 ppm Ag) than type 2 (149-1,288 ppm S, <90-146 As, <65-928 ppm Ag). No mineral inclusions of sulphide or arsenide in native copper were observed at the electron-microprobe scale. Primary igneous fabrics are preserved, but the basaltic flows are pervasively oxidised and plagioclase is albitised. Chlorite replaces plagioclase and forms interstitial aggregates in the groundmass and has Fe/(Fe+Mg) ratios ranging from 0.29 to 0.36 with calculated temperatures between 155°C and 182°C. Copper sulphides in vacuoles and veinlets are associated with malachite, fibro-radiating albite and yarrowite (Cu9S8 with up to 0.3 wt% Ag). Bulk-rock concentrations of thallium and lithium range from 70 to 310 ppb and 10 to 22 ppm, respectively, and thallium is positively correlated with Fe2O3. Such concentrations of thallium and lithium are typical of spilitisation during heated seawater-basalt interaction. Spilitisation is consistent with the regional geological setting of deepwater-facies sedimentation, but is different from current models for volcanic red-bed copper, which indicate subaerial oxidation of volcanic flows. The volcanic red-bed copper model should be re-examined to account for native copper mineralisation in basalts altered by warm seawater.

Cabral, Alexandre Raphael; Beaudoin, Georges

2007-11-01

74

The effects of repeated cycles of calcination and carbonation on a variety of different limestones, as measured in a hot fluidized bed of sand  

Microsoft Academic Search

The capacity of calcined limestone to react repeatedly with COâ, according to CaO{sub cr} + CO{sub 2(g)} = CaCO{sub 3(cr)} (eq I), and also its regeneration in the reverse reaction have been studied in a small, electrically heated fluidized bed of sand, for five different limestones. The forward step of eq I is a promising way of removing COâ from

Paul S. Fennell; Roberta Pacciani; John S. Dennis; John F. Davidson; Allan N. Hayhurst

2007-01-01

75

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

76

Sand particle dislodgement in windblown sand  

NASA Astrophysics Data System (ADS)

The incipient motion of sand particle from sand bed plays a very important role in the prediction of windblown sand. In this paper, we proposed a new method for predicting the incipient motion of sand particle based on wind speed fluctuation as follows, when the wind speed is larger than the critical wind speed, if the total impulse on sand particle is larger than the critical impulse, incipient motion of sand particle would take place, otherwise if not. Furthermore, from the analysis of entrainment in the rolling and lifting modes, we come to the following conclusion. When the average wind speed is smaller than the critical wind speed, if the average wind speed is used to judge the incipient motion of sand particle, one will underestimate the number of sand particles jumping from the bed, if the instantaneous wind speed is used to judge incipient motion of sand particle, one will overestimate the number of sand particles jumping from the bed; When the average wind speed is larger than the critical wind speed, either the average or the instantaneous wind speeds is used to judge the incipient motion of sand particles, one will overestimate the number of sand particles jumping from the bed.

Bo, Tian-Li; Li, Zheng; Zheng, Xiao-Jing

2014-12-01

77

Depositional mechanisms controlling formation of coarse fluvial conglomerates in the lower triassic continental red beds of middle europe  

Microsoft Academic Search

Coarse fluvial conglomerates containing numerous cobbles and boulders occur in various formations within the Lower Triassic continental red beds of Middle Europe. The rudites mainly originate as longitudinal gravel bars in highly-braided river systems with narrowly-spaced and straight to slightly sinuous channels. The high-energy stream sedimentation and the frequent and rapid lateral shifting of the watercourses control origin, distribution and

Detlef Mader

78

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

79

Chemical evaluation of sand material sources for beach replenishment along the coast of the Gulf of Aqaba, Red Sea  

Microsoft Academic Search

Four potential borrow sites (sources of sand) for beach nourishment were selected at the Aqaba terraces and dredged offshore sand along the Jordanian coast of the Gulf of Aqaba, and at Al-Humaimah and Wadi Rum sand dunes north and northeast of Aqaba town. An elution test has been performed on the sand materials of these potential borrow sites to determine

Mohammed Rasheed; Entisar El-Hihi; Saber Al-Rousan; Ahmad Abu-Hilal

2009-01-01

80

The influence of microbial mats on the formation of sand volcanoes and mounds in the Red Sea coastal plain, south Jeddah, Saudi Arabia  

NASA Astrophysics Data System (ADS)

Extensive areas covered by microbial mats have been found in the upper intertidal flats and supratidal pools in the Red Sea coastal plain of south Jeddah, Saudi Arabia. Numerous microbially controlled sediment-surface morphologies are evident, such as flat cohesive mats that commonly pass into mats with wrinkles, reticulates, and tufts, together with erosion pockets and mat chips. These microbial mats form cohesive surface layers that lead to biostabilization of the sediment surface. Fluidization of the underlying sediments is due to tidal influences and pressurized gas escape from decay and photosynthesis of microbial mats and causes deformation and rupture of the cohesive surface mat layer via vertical and sub-vertical pipes. Extrusion of fluidized sediments and water through these pipes leads to redeposition of sediment grains above the surface mat layer to form sand volcanoes and mounds. Most of the sand volcanoes present in the intertidal flats and supratidal pools show a symmetrical morphology, whereas in tidal channels asymmetrical forms are more common. Extrusion of underlying sediments through several adjacent vents leads to coalescence of sand volcanoes to form sand mounds. In this study sand volcanoes are also compared with other cone-like features from the Red Sea, such as gas domes and crab mounds. This comparison should help in differentiating similar cone-like features associated with microbial mats in the rock record.

Taj, Rushdi J.; Aref, Mahmoud A. M.; Schreiber, B. Charlotte

2014-08-01

81

Tectonic significance of porosity and permeability regimes in the red beds formations of the South Georgia Rift Basin  

NASA Astrophysics Data System (ADS)

A simple, new porosity/permeability-depth profile was developed from available laboratory measurements on Triassic sedimentary red beds (sandstone) from parts of the South Georgia Rift (SGR) basin in order to investigate the feasibility for long-term CO2 storage. The study locations were: Sumter, Berkeley, Dunbarton, Clubhouse Crossroad-3 (CC-3) and Norris Lightsey wells. As expected, both porosity and permeability show changes with depth at the regional scale that was much greater than at local scale. The significant changes in porosity and permeability with depth suggest a highly compacted, deformed basin, and potentially, a history of uplift and erosion. The permeability is generally low both at shallow (less than 1826 ft/556.56 m) and deeper depths (greater than 1826 ft/556.56 m). Both porosity and permeability follow the normal trend, decreasing linearly with depth for most parts of the study locations with the exception of the Norris Lightsey well. A petrophysical study on a suite of well logs penetrating the Norris Lightsey red beds at depths sampled by the core-derived laboratory measurements shows an abnormal shift (by 50%) in the acoustic travel time and/or in the sonic-derived P-wave velocity that indicates possible faulting or fracturing at depth. The departure of the Norris Lightsey's porosities and permeabilities from the normal compaction trend may be a consequence of the existence of a fault/fracture controlled abnormal pressure condition at depth. The linear and non-linear behaviors of the porosity/permeability distribution throughout the basin imply the composition of the SGR red beds, and by extension analog/similar Triassic-Jurassic formations within the Eastern North American Margin have been altered by compaction, uplift, erosion and possible faulting that have shaped the evolution of these Triassic formations following the major phase of rifting.

Akintunde, Olusoga M.; Knapp, Camelia C.; Knapp, James H.

2014-09-01

82

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

83

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

84

Multiscale bed form interactions and their implications for the abruptness and stability of the downwind dune field margin at White Sands, New Mexico, USA  

NASA Astrophysics Data System (ADS)

downwind margin of White Sands dune field is an abrupt transition from mobile aeolian dunes to a dune-free vegetated surface. This margin is also relatively stable; over the past 60 years it has migrated several times more slowly than the slowest dunes within the dune field, resulting in a zone of dune coalescence, aggradation, and, along most of the margin, development of a dune complex (i.e., dunes superimposed on draas). Repeat terrestrial laser scanning surveys conducted over a 3 month period demonstrate that sediment fluxes within the dune complex decrease on approach to the margin. Computational fluid dynamics modeling indicates that this decrease is due, in part, to a decrease in mean turbulent bed shear stress on the lee side of the dune complex as a result of flow line divergence or sheltering of the lee-side dunes by the stoss side of the dune complex. Conservation of mass demands that this decrease in bed shear stress causes aggradation. We speculate that aggradation on the lee side of the dune complex further enhances the sheltering effect in a positive feedback, contributing to the growth and/or maintenance of the dune complex and a relatively abrupt and stable dune field margin. Our model and data add to a growing body of evidence that aeolian dune field patterns are influenced by feedbacks that occur at scales larger than individual dunes.

Pelletier, Jon D.; Jerolmack, Douglas J.

2014-11-01

85

Voidage and pressure profile characteristics of sand-iron ore-coal-FCC single-particle systems in the riser of a pilot plant circulating fluidized bed  

SciTech Connect

Hydrodynamic behaviors of single system of particles were investigated in a circulating fluidized bed (CFB) unit. Particles belonging to Geldart groups A and B like sand of various sizes (90, 300, 417, 522, 599, and 622 mu m), FCC catalyst (120 mu m), iron ore (166 and 140 {mu} m), and coal (335 and 168 {mu} m) were used to study the hydrodynamic characteristics. Superficial air velocity used in the present study ranged between 2.01 and 4.681 m/s and corresponding mass fluxes were 12.5-50 kg/(m{sup 2} s). A CFB needs the creation of some special hydrodynamic conditions, namely a certain combination of superficial gas velocity, solids circulation rate, particle diameter, density of particle, etc. which can give rise to a state wherein the solid particles are subjected to an upward velocity greater than the terminal or free fall velocity of the majority of the individual particles. The hydrodynamics of the bed was investigated in depth and theoretical analysis is presented to support the findings. Based on gas-solid momentum balance in the riser, a distinction between apparent and real voidage has been made. The effects of acceleration and friction on the real voidage have been estimated. Results indicated a 0.995 voidage for higher superficial gas velocity of 4.681. m/s.

Das, M.; Meikap, B.C.; Saha, R.K. [Indian Institute for Technology, Kharagpur (India). Dept. for Chemical Engineering

2008-06-15

86

The effects of repeated cycles of calcination and carbonation on a variety of different limestones, as measured in a hot fluidized bed of sand  

SciTech Connect

The capacity of calcined limestone to react repeatedly with CO{sub 2}, according to CaO{sub cr} + CO{sub 2(g)} = CaCO{sub 3(cr)} (eq I), and also its regeneration in the reverse reaction have been studied in a small, electrically heated fluidized bed of sand, for five different limestones. The forward step of eq I is a promising way of removing CO{sub 2} from the exhaust of, for example, a coal-fired power station, ready for sequestration or as part of a scheme to generate H{sub 2} using an enhanced water-gas shift reaction. The reverse step regenerates the sorbent. The uptake of CO{sub 2} by CaO, produced by calcining limestone, was measured using a bed of sand fluidized by N{sub 2} at about 1023 K. For each experiment, a small quantity of limestone particles was added to the hot sand, whereupon the limestone calcined to produce CaO. Calcination was completed in about 500 s for particles of a mean diameter of about 600 {mu}m. Next, CO{sub 2} was added to the fluidizing nitrogen to carbonate the CaO for about 500 s. Measurements of (CO{sub 2}) in the off-gases enabled the rates of calcination and the subsequent carbonation to be measured as functions of time. Many successive cycles of calcination and carbonation were studied. The forward step of reaction I is shown to exhibit an apparent final conversion, which decreases with the number of cycles of reaction; the final conversion fits well to a correlation from the literature. The reverse (calcination) reaction always proceeded to completion. It was found that the carrying capacity of CaO for CO{sub 2} on the nth cycle of carbonation was roughly proportional to the voidage inside pores narrower than about 150 nm in the calcined CaO before carbonation began. Thus, morphological changes, including reduction in the volume of pores narrower than 150 nm within a calcined limestone, were found to be responsible for much of the fall in conversion of reaction I with increasing numbers of cycles. 19 refs., 9 figs., 4 tabs.

Paul S. Fennell; Roberta Pacciani; John S. Dennis; John F. Davidson; Allan N. Hayhurst [University of Cambridge, Cambridge (United Kingdom). Department of Chemical Engineering

2007-08-15

87

Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile  

NASA Astrophysics Data System (ADS)

Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiapó, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

Bell, C. M.; Suárez, M.

88

Morphology and Hydraulics of Nine Sand-bed Fluvial Bifurcations from the Mossy Delta, SK: Implications for Their Stability  

NASA Astrophysics Data System (ADS)

The distributary channel network of the Mossy Delta, SK consists of ~25 presently-active bifurcations created by channel splitting around river mouth bars during a 70 year history of delta growth. Detailed morphologic and hydraulic data from nine bifurcations are analyzed here to define the processes that determine their stability. Processes considered include bedload steering by adverse bed slopes, sediment and flow steering by secondary circulation, flow steering by inherited channel planform, and gradient advantage due to external boundary conditions. Stability of the bifurcations was determined from serial aerial photo analysis. Results indicate that the net topology and planforms of the bifurcations were set early during deposition of river mouth bars. Inherited alignment of a bifurcate channel thalweg with the main stem does not play a large role in subsequent bifurcation evolution; today roughly half of the side-channels take a greater proportion of the flow. After creation, bifurcate channels decreased in width by c. 15 %, with most of the reduction occurring in the first decade through bank accretion of scroll bars. Modern bifurcate channel depths and widths follow a hydraulic geometry scaling law (although they are wider and shallower than typical river channels), indicating a morphodynamically stable channel network. Most active bifurcations today are asymmetric; the average proportion of discharge through subordinate channels is 37 % with variation from 20 to 50 %. Local water surface slopes are flat approaching a bifurcation and steepen down the bifurcate arms, with the steeper slope in the shallower channel. All subordinate bifurcate channels possess morphologic ramps from the main channel with adverse bed slopes of 3-5 %. Although this suggests topographic steering of bedload is an important process in maintaining stability, it is not the only controlling process, because the subordinate ramp is shallower in c. 30 % of the cases.

Slingerland, R.; Klein, F. E.; Edmonds, D. A.; Best, J. L.; Parsons, D. R.; Bridge, J. S.; Janesko, D.; Smith, N. D.

2007-12-01

89

An Experimental Study of Sand Transport over an Immobile Gravel Substrate  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effects of a stepwise addition of sand to an immobile gravel bed on the sand transport rate and configuration of the sand bed was investigated in a laboratory flume channel. Detailed measurements of sand transport rate, bed texture, and bed topography were collected for four different discharge...

90

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

91

Fluvial conglomerates in continental red beds of the Buntsandstein (Lower Triassic) in the Eifel (F.R.G.) and their palaeoenvironmental, palaeogeographical and palaeotectonic significance  

NASA Astrophysics Data System (ADS)

Fluvial conglomerates occur in a variety of facies within the continental red bed sequence of the Buntsandstein (Lower Triassic) in the Eifel at the western margin of the Mid-European Triassic Basin. The alluvial rudites are classified into channel-floor lag, channel-bar, channel-top lag, crevasse-splay and floodplain-lag conglomerates. The conglomerates were predominantly deposited in Scott-type, and in subordinate amounts also in Donjek-type and South Sasketchewan-type braided rivers. The vertical distribution of clast size and frequency within the megacycles reflects the palaeotectonic sequence of uplift events in the source area, resulting in supply of large amounts of coarse detritus which cause recurrences in fluvial style. Gradually upwards diminishing size and abundance of gravel indicate continuous lowering of source area relief during weakening endogenic activity or even tectonic quiescence after final peneplanation. The palaeoenvironmental interpretation of the individual members and the palaeotectonic analysis of the conglomerate successions are combined with a reconstruction of the depositional history of the Eifel Buntsandstein which comprises an evolution of fluvial deposition. The terminal stage of the palaeoenvironmental evolution is highlighted by a climax of regional diversification of conglomerate sedimentary milieu. The horizontal distribution of clast size and abundance delineates the palaeogeographical evolution of the elongated Eifel Basin, giving evidence of a progressive sidewards extension of the depositional area with time. Lateral supply from parts of the western margin and mixing of proximally derived coarse clasts with distantly delivered fine detritus result in highly inhomogeneous gravel distributions within the sedimentary region often not being characterized by gradually decreasing size and abundance of gravel in downstream direction. The stepwise southwestwards shift of the marginal centre of supply of coarse gravel with time during the course of the lateral extension of the basin results in ascension of the fluvial conglomerate wedges into successively younger formations comprising consecutively Middle Buntsandstein, Upper Buntsandstein, Lower Muschelkalk, Middle Muschelkalk and finally Middle Keuper. The extraformational conglomerates mainly delineate the palaeogeographical framework, whereas the intraclastic rudites primarily give evidence of processes operating within the depositional area, reflecting erosion and reworking of overbank sequences with floodplain fines, palaeosols and aeolian dune sands during lateral channel shift. The Bröckelbank intraformational carbonate breccias to conglomerates originating from reworking of calcrete palaeosols are a peculiar facies element with particularly high palaeoenvironmental significance. They document the frequency, spatial extension and temporal persistence of pedogenesis within the alluvial plain. The size of the extraformational clasts gives evidence of the range of current velocities during aggradation of the channels. The distribution of conglomerate type and clast characteristics within cyclothems indicates the presence of stage fluctuations and variations in discharge in parts of the sequence. The preservation of complete cyclothems or the multistoreying of channel bar conglomerates reflects the differential importance of the two main mechanisms controlling accumulation of sediments in the alluvial plain: primary-depositional restriction to suppression of formation and secondary-erosional removal to destruction of finer-grained channel sediments, floodplain deposits and aeolian dune sands or palaeosols. Condensation of a series of depositional events within monotonous stacked conglomerate sequences obliterates the full range of sedimentary processes and mimics periods of long-term stability of conglomerate formation. Waning-flow mud drapes are particularly significant instruments to split up the individual genetical units of formation of fluvial conglomerates, often comprising discrete flood phases separated by stage fluctuations

Mader, Detlef

1985-05-01

92

Slow Sand Filtration: Influences of Selected Process Variables  

Microsoft Academic Search

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 (shown above). Temperature, sand bed depth, and sand size also had strong influence. La actividad biológica dentro de la cama de arena ejerce la influencia más grande en la eficiencia de la extracción

William D. Bellamy; David W. Hendricks; Gary S. Logsdon

1985-01-01

93

Quantitative analysis of iron oxide concentrations within Aptian-Albian cyclic oceanic red beds in ODP Hole 1049C, North Atlantic  

NASA Astrophysics Data System (ADS)

Aptian-Albian sediments in Core 12X of Hole 1049C (ODP Leg 171B) are characterized by high-frequency cycles that consist of alternating layers of red and green/white clayey chalk, and claystone. The first derivative curves of diffuse reflectance spectra (DRS) for samples of different colors reveal that red (brown and orange) samples show clear peaks corresponding to hematite and goethite. Following treatment using the CBD (citrate-bicarbonate-dithionite) procedure, the red samples lost their red color and corresponding peaks in the first derivative curve, and became greenish or whitish. Therefore, hematite and goethite are the minerals responsible for the reddish change in sample color. However, these minerals behave differently from each other in terms of determining the color of sediment: hematite imparts a red color, whereas goethite imparts a yellow color. Therefore, a change in the proportions of hematite and goethite can cause a change in sediment color from orange to brown. To obtain the absolute contents of iron oxides in these sediments, we performed a quantitative analysis using DRS with multiple linear regression. The results reveal that the Albian brown beds contain 0.13-0.82% hematite (average value, 0.51%) and 0.22-0.81% goethite (average value, 0.58%). The Aptian orange beds contain 0.19-0.46% hematite (average value, 0.35%) and 0.29-0.67% goethite (average value, 0.50%). X-ray diffraction analysis of the Aptian and Albian cycles reveals no clear variations in mineral content with sediment color. It is suggested that hematite and goethite were derived from oxic environments during the period of deposition and early diagenesis. The oxic conditions were probably determined by the low accumulation rate of organic matter and the high content of dissolved oxygen in bottom water.

Li, Xiang; Hu, Xiumian; Cai, Yuanfeng; Han, Zhiyan

2011-03-01

94

The effect of the particle size of alumina sand on the combustion and emission behavior of cedar pellets in a fluidized bed combustor  

Microsoft Academic Search

A combustion experiment with cedar pellet fuel was carried out in a semi-pilot scale bubbling fluidized bed combustor. The effects of temperature, fluidized velocity, and bed material particle size on the emission of NOx, CO, and CO2 were investigated. The variations in the temperature profile and gas concentration in the vertical and horizontal directions of the combustor were also studied.

Jun Han; Heejoon Kim; Wataru Minami; Tadaaki Shimizu; Guanghui Wang

2008-01-01

95

The paleoclimatic and geochronologic utility of coring red beds and evaporites: a case study from the RKB core (Permian, Kansas, USA)  

NASA Astrophysics Data System (ADS)

Drill core is critical for robust and high-resolution reconstructions of Earth's climate record, as well demonstrated from both marine successions and modern long-lived lake systems. Deep-time climate reconstructions increasingly require core-based data, but some facies, notably red beds and evaporites, have garnered less attention for both paleoclimatic and geochronologic analyses. Here, we highlight studies from the Rebecca K. Bounds (RKB) core, a nearly continuous, >1.6 km drill core extending from the Cretaceous to the Mississippian, recovered from the US Midcontinent by Amoco Production Company in 1988, and serendipitously made available for academic research. Recent research conducted on this core illustrates the potential to recover high-resolution data for geochronologic and climatic reconstructions from both the fine-grained red bed strata, which largely represent paleo-loess deposits, and associated evaporite strata. In this case, availability of core was instrumental for (1) accessing a continuous vertical section that establishes unambiguous superposition key to both magnetostratigraphic and paleoclimatic analyses, and (2) providing pristine sample material from friable, soluble, and/or lithofacies and mineralogical species otherwise poorly preserved in surface exposures. The potential for high-resolution paleoclimatic reconstruction from coring of deep-time loess strata in particular remains severely underutilized.

Soreghan, Gerilyn S.; Benison, Kathleen C.; Foster, Tyler M.; Zambito, Jay; Soreghan, Michael J.

2014-08-01

96

SAND REPORT SAND2002xxxx  

E-print Network

SAND REPORT SAND2002­xxxx Unlimited Release August 2002 Discrete Optimization Models for Protein://www.ntis.gov/ordering.htm DEPARTMENTOF ENERGY . . UNITED STATES OF AMERICA #12; SAND2002-xxxx Unlimited Release Printed August 2002

Newman, Alantha

97

Mystery Sand  

NSDL National Science Digital Library

In this activity, learners play with surprising sand that doesn’t 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.

2012-06-08

98

Simulation of wind-blown sand movement and probability density function of liftoff velocities of sand particles  

Microsoft Academic Search

Accurately describing the probability density function (PDF) of liftoff or initial velocities of wind-blown sand ejecting from a sand bed is fundamental to understanding the mechanisms of wind-blown sand movement. Our objective was to investigate the efficacy of developing the PDF of liftoff velocities based on wind tunnel measurements of sand flux and wind speed profile. On the basis of

Ning Huang; Xiao Jing Zheng; You-He Zhou; R. Scott Van Pelt

2006-01-01

99

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

100

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

101

Modelling the effect of canal bed elevation on seepage and water table rise in a sand box filled with loamy soil  

Microsoft Academic Search

The HYDRUS 2D finite difference two-dimensional water balance model was experimentally tested for transient and steady state\\u000a seepage flux, mound height, and piezometric water level from soil surface as a function of time and horizontal distance from\\u000a the centre of the canal (half width = 45 cm) under different canal bed elevations (20, 0, ?40, ?80 and ?120 cm denoted as\\u000a experiments D1, D2,

V. Phogat; R. S. Malik; Sanjay Kumar

2009-01-01

102

Sand Storage  

USGS Multimedia Gallery

A sand storage silo at Steamtown National Historic Site. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially when the ra...

103

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

104

An optical method of measuring the temperature in a fluidised bed combustor  

SciTech Connect

The paper analyses the dynamic aspects of the temperature field in a fluidised bed of solids particles (e.g., sand) in which a gaseous fuel is being burned. Such a hot bed emits electromagnetic radiation within the visible range and this can be recorded using a digital video camera. This fact has been used to develop a method for measuring the bed's temperature in the line of sight, through the quartz sides of the reactor. A solid probe is only used for calibration. Video recordings were obtained covering different regions of the bed over three wavelength bands, red, green and blue. In the course of an experiment, the mean temperature of the bed, measured with thermocouples, was raised from ambient to 1300 K, at a rate of {proportional_to} 1 K/s. The data collected were used for calibration, with the brightness of individual pixels converted to a temperature scale. The calibration can then be used to investigate the dynamic temperature distribution within the field of view, in individual elements of the bed. This can also help the study of heat transfer in the bed, its distribution and dissipation. Using this method, it is possible to make direct observations of the intermittent combustion of gaseous fuels in a bubbling fluidised bed. The results provide direct proof that the temperature gradients observed within such beds are associated with exothermic processes within fast moving bubbles. The method could be adapted to studying, e.g., the combustion of solid fuels. (author)

Zukowski, Witold; Baron, Jerzy; Bulewicz, Elzbieta M.; Kowarska, Beata [Cracow University of Technology, Faculty of Chemical Engineering and Technology, ul. Warszawska 24, 31-155 Krakow (Poland)

2009-07-15

105

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

106

THE SIMULATION OF WIND-BLOWN SAND MOVEMENT AND PROBABILITY DENSITY FUNCTION OF LIFT-OFF VELOCITIES OF SAND GRAINS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Accurately describing the probability density function (PDF) of lift-off or initial velocities of wind-blown sand ejecting from a sand bed is fundamental to understanding the mechanisms of wind-blown sand movement. Our objective was to investigate the efficacy of developing the PDF of lift-off veloc...

107

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

108

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

109

Seismites in continental sand sea deposits of the Late Cretaceous Caiuá Desert, Bauru Basin, Brazil  

NASA Astrophysics Data System (ADS)

Two large-scale sediment deformation structures, minor fold occurrences in cross-bedded sand dune deposits and complex convolute folds, are observed in red sandstones, in a zone about 1.5 km long in floodway cuts at the Sérgio Motta/Porto Primavera dam, São Paulo state, Brazil. The most important structures are confined to planar zones, up to 10 m thick, in undeformed dune foreset strata were they can be traced laterally for about 50-60 m. The sandstones are part of the Rio Paraná Formation, Caiuá Group, which accumulated in a great sand sea of about 100,000 km 2. The Caiuá Desert developed during the Late Cretaceous in the southern part of the Bauru Basin, an intracontinental subsiding area in the central-southern part of the South-American Platform. The basin was filled by a sandy sequence about 300 m thick. The sand sea deposits correspond to the Caiuá Group and comprise: a) deposits of dry sand sheets (Santo Anastácio Formation), b) deposits of medium-sized dunes and humid interdunes of the sand sea peripheral zones (Goio Erê Formation), and c) deposits of large-sized complex aeolian dunes and draas, that correspond to the central part of the inland sand sea (Rio Paraná Formation). The deformations in the sediments are attributed to the effects of fluidization, liquefaction and shear stress, which are interpreted as being earthquake-induced structures, mainly because: (1) the deformed horizons are confined between undeformed cross-bedded strata, (2) the complex convolute folds sometimes include nappe-like structures that overlie foreset facies, (3) during the Bauru Basin infilling there was tectonic activity associated with alkaline volcanism on the borders of the basin and related silicification in the central-southern part. The main silicification zones are aligned to regional lineaments that cross the area near the large-scale sedimentary deformation structures.

Fernandes, Luiz Alberto; de Castro, Alice Bonatto; Basilici, Giorgio

2007-07-01

110

Scaling laws in aeolian sand transport  

NASA Astrophysics Data System (ADS)

Via wind tunnel experiments on aeolian sand transport, we provide evidences that over an erodible bed the grain velocity in the saltation layer and the saltation length are almost invariant with the wind strength, whereas over a non-erodible bed these quantities vary significantly with the air friction speed. It results that the particle transport rate over an erodible bed does not exhibit a cubic dependence with the air friction speed, as predicted by Bagnold, but a quadratic one. This contrasts with saltation over a non-erodible bed where the cubic Bagnold scaling holds. Our findings emphasize the crucial role of the boundary conditions at the bed and may have important practical consequences for aeolian sand transport in natural environment. Reference: T.D. Ho, A. Valance, P. Dupont and A. Ould El Moctar, Phys. Rev. Lett. 106, 094501 (2011).

Valance, Alexandre; Ho, Tuan Duc; Ould El Moctar, Ahmed; Dupont, Pascal

2013-04-01

111

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

112

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) ...

113

Musical Sands  

Microsoft Academic Search

MR. CARUS-WILSON'S failure (January 9, p. 222) to obtain sounds, from, ``millet seed'' sand of highly spherical grains puts a difficulty in the way of the suggestion made, in ``Sound'' by Poynting and Thomson, though I do not think that it finally disposes of it.

J. H. Poynting

1908-01-01

114

Flue gas desulfurization in an internally circulating fluidized bed reactor  

Microsoft Academic Search

An internally circulating fluidized bed reactor (ICFBR) was used as a desulfurization apparatus in this study. The height of the bed was 2.5 m, and the inner diameter was 9 cm. The bed materials were calcium sorbent and silica sand. The effects of the operating parameters of the flue gas desulfurization including relative humidity, particle size of the calcium sorbent,

Chen Yeon Chu; Shyh Jye Hwang

2005-01-01

115

SOLID-LIQUID SEPARATION OF SWINE MANURE WITH POLYMER TREATMENT AND SAND FILTRATION  

Microsoft Academic Search

Small particles typical of liquid swine manure often clog sand filter beds and fine filters. We evaluated the effec- tiveness of polymer flocculants to improve drainage and filtration performance of sand filter beds by increasing the particle size of manure. A pilot separation unit was evaluated at the Swine Unit of the NCSU Lake Wheeler Road Laboratory in Ra- leigh,

M. B. Vanotti; J. M. Rice; A. Q. Ellison; P. G. Hunt; F. J. Humenik; C. L. Baird

116

Industrial sand and gravel  

USGS Publications Warehouse

Domestic production of industrial sand and gravel in 2010 was about 26.5 Mt (29.2 million st), a 6-percent increased from 2009. Certain end uses of industrial sand and gravel, such as sand for container glass, golf course sand, recreational sand, specialty glass and water filtration, showed increased demand in 2010.

Dolley, T.P.

2011-01-01

117

Formation of Two-Dimensional Sand Ripples under Laminar Shear Flow Vincent Langlois and Alexandre Valance  

E-print Network

Formation of Two-Dimensional Sand Ripples under Laminar Shear Flow Vincent Langlois and Alexandre 20 June 2005) The process of ripple formation on a two-dimensional sand bed sheared by a viscous fluid is investigated theoretically. The sand transport is described taking into account both the local

118

Physica D 195 (2004) 207228 Blown by wind: nonlinear dynamics of aeolian sand ripples  

E-print Network

Physica D 195 (2004) 207­228 Blown by wind: nonlinear dynamics of aeolian sand ripples Hezi Yizhaqa continuum model is considered that describes the dynamics of two-dimensional aeolian sand ripples analysis using this model shows that a flat sand bed exposed to the action of wind is linearly unstable

Balmforth, Neil

119

Intertidal sand body migration along a megatidal coast, Kachemak Bay, Alaska  

E-print Network

Intertidal sand body migration along a megatidal coast, Kachemak Bay, Alaska Peter N. Adams,1 the timing and magnitude of alongshore migration of intertidal sand bed forms over a cobble substrate during a 22-month observation period. Two separate sediment packages (sand bodies) of 1­2 m amplitude and $200

120

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

121

Performance evaluation of a pilot scale vortexing fluidized bed combustor  

Microsoft Academic Search

To understand vortexing fluidized bed combustor (VFBC) performances, an investigation was carried out in a 0.45 m diameter\\u000a and 4.45 m height pilot scale VFBC. Rice husks, corn, and soybean were used as the biomass feedstock and silica sand serving\\u000a as the bed material. The bubbling bed temperature was controlled by using water injected into the bed. The experimental results

Chien-Song Chyang; Kuo-Chao Lo; Kuo-Lian Wang

2005-01-01

122

SAND REPORT SAND2003-0112  

E-print Network

SAND REPORT SAND2003-0112 Unlimited Release Printed January 2003 Cold War Context Statement Sandia://www.ntis.gov/help/ordermethods.asp?loc=7-4-0#online #12;3 SAND2003-0112 Unlimited Release Printed January 2003 Cold War Context Statement

Fuerschbach, Phillip

123

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

124

Bed Bugs FAQs  

MedlinePLUS

... gov . Parasites - Bed Bugs Parasites Home Share Compartir Bed Bugs FAQs On this Page What are bed ... are bed bugs treated and prevented? What are bed bugs? Bed bugs ( Cimex lectularius ) are small, flat, ...

125

Creating Sand Dunes  

NSDL National Science Digital Library

This experiment demonstrates the formation and movement of sand dunes. Students will simulate the effects of wind using a hair dryer on bare sand, then add stones and grass to observe how the effects are changed. They should be able to explain how sand dunes are formed, what circumstances effect the movement or formation of sand dunes, and relate this information to soil conservation.

1998-01-01

126

Industrial sand and gravel  

USGS Publications Warehouse

Domestic production of industrial sand and gravel in 2011 was about 30 Mt (33 million st), increasing slightly compared with 2010. Some important end uses for industrial sand and gravel include abrasives, filtration, foundry, glassmaking, hydraulic fracturing sand (frac sand) and silicon metal applications.

Dolley, T.P.

2012-01-01

127

Industrial sand and gravel  

USGS Publications Warehouse

Domestic production of industrial sand and gravel in 2012 was about 49.5 Mt (55 million st), increasing 13 percent compared with that of 2011. Some important end uses for industrial sand and gravel include abrasives, filtration, foundry, glassmaking, hydraulic fracturing sand (frac sand) and silicon metal applications.

Dolley, T.P.

2013-01-01

128

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

129

Sand boils induced by the 1993 Mississippi River flood: Could they one day be misinterpreted as earthquake-induced liquefaction?  

USGS Publications Warehouse

In areas that are seismically active but lacking clear surficial faulting, many paleoearthquake studies depend on the interpretation of ancient liquefaction features (sand blows) as indicators of prehistoric seismicity. Sand blows, however, can be mimicked by nonseismic sand boils formed by water seeping beneath levees during floods. We examined sand boils induced by the Mississippi River flood of 1993 in order to compare their characteristics with sand blows of the New Madrid earthquakes of 1811-1812. We found a number of criteria that allow a distinction between the two types of deposits. (1) Earthquake-induced liquefaction deposits are broadly distributed about an epicentral area, whereas flood-induced sand boils are limited to a narrow band along a river's levee. (2) The conduits of most earthquake-induced sand blows are planar dikes, whereas the conduits of flood-induced sand boils are most commonly tubular. (3) Depression of the preearthquake ground surface is usual for sand blows, not for sand boils. (4) Flood-induced sand boils tend to be better sorted and much finer than sand-blow deposits. (5) Source beds for earthquake-induced deposits occur at a wide range of depths, whereas the source bed for sand boils is always near surface. (6) Materials removed from the walls surrounding the vent of a sand blow are seen inside sand blows, but are rarely seen inside sand boils. In general, flood-induced sand boils examined are interpreted to represent a less-energetic genesis than earthquake-induced liquefaction.

Li, Y.; Craven, J.; Schweig, E.S.; Obermeier, S.F.

1996-01-01

130

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

131

Sand waves, bars, and wind-blown sands of the Rio Orinoco, Venezuela and Colombia  

USGS Publications Warehouse

During March 1982, a reconnaissance study was carried out along a reach of the Rio Orinoco between Puerto Ayacucho and Ciudad Bolivar. This was the low-flow season. Samples of bed material and suspended sediments were collected, sonic records of the bed were obtained at several locations, and the exposed bars and sand waves were studied at four locations. Sounding records were obtained at two of these locations during June and November when flow covered the bars, and additional studies were made on the ground at some of these same sites during March 1983. The bed of the river is mostly sand with small quantities, about 5 percent by weight on average, of gravel. Suspended- sediment concentrations were low, ranging between 20 milligrams per liter above Rio Apure to almost 40 milligrams per liter below its confluence with the Rio Orinoco. The annual sediment load is estimated to be 240x10 6 megagrams per year. During the dry season, 35 percent or more of the bed is exposed in the form of large bars composed of many sand waves. Trade winds blow upriver and there is substantial upriver transport of river sediments by the wind. If the bars contain very coarse sands and fine gravel, deflation forms a lag deposit that armors the bar surface and prevents further erosion. Theoretical calculations show that the lower limit for the fraction of the bed that needs to be covered with nonmoving particles to prevent further erosion and the smallest size of the armor particles depend only on wind speed. Calculations of bed-material transport were made for a typical wide and narrow section of the river; the annual load, excluding the wash load, is about 30 x 10 6 megagrams per year. A new definition for wash load is proposed; it is material that can be suspended as soon as its motion is initiated. For the Rio Orinoco, this is material finer than 0.1 millimeters.

Nordin, Carl F.; Perez-Hernandez, David

1989-01-01

132

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

133

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

134

Multifuel bubbling bed fluidized bed combustor system  

Microsoft Academic Search

Apparatus for generating heat is described, comprising: a fluidized bed pyrolyzer; a fluidized bed combustor; a combustor vessel; means for supporting a combustor bed of granular material within the combustor vessel; means for adding the gaseous effluents removed from the pyrolyzer bed to the combustor bed; means for adding granular material to the combustor bed; means for removing gaseous effluents

Wormer

1989-01-01

135

CONTRACTOR REPORT SAND927005  

E-print Network

CONTRACTOR REPORT SAND92­7005 Unlimited Release UC­261 Fatigue of Fiberglass Wind Turbine Blade . #12;Distribution CategoryUC-261 SAND92-7005 UnlimitedRelease PrintedAugust 1992 FATIGUE OF FIBERGLASS

136

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.

137

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

138

Eolian cover sands: a sedimentologic model and paleoenvironmental implications  

SciTech Connect

In periglacial areas, accumulations of eolian sand commonly form low-relief blankets without well-developed dunes. Internally, these sandsheet deposits exhibit subhorizontal lamination rather than high-angle cross-bedding. Such cover sands of late-Pleistocene age mantle extensive areas in northern Europe, but have been reported more rarely from North America. The processes by which cover sands, as opposed to dunes, accumulate have not yet been determined conclusively. Wind ripples and sand dunes do not form a continuum; flow separation and avalanching and negligible in the former and vital in the latter. Accretion of a sand patch into a mound sufficient to cause flow separation and dune growth requires a consistently available supply of loose sand. In cover-sand areas, sand may be immobilized prior to dune development by several factors: (1) a sparse vegetation cover, (2) moist ground conditions, (3) snow cover, and (4) a shallow permafrost table and/or an ice-cemented active layer. Detailed sedimentologic studies may allow discrimination among these various controls. The importance of the individual controlling factors can vary seasonally in a given deposit, as well as between deposits in different paleogeographic settings. However, all factors imply more mesic conditions than those associated with many dune deposits. The association of cover sands with paraboloid dunes is also consistent with somewhat moist conditions. The relatively mesic nature of cover sands controls their Pleistocene distribution; they become decreasingly important relative to dunes in maritime-to-continental transects across Alaska and northern Europe.

Lea, P.D.

1985-01-01

139

Design and management of conventional fluidized-sand biofilters  

Microsoft Academic Search

Fluidized-sand beds are an efficient, relatively compact, and cost-competitive technology for removing dissolved wastes from recirculating aquaculture systems, especially in relatively cool or coldwater applications that require maintaining consistently low levels of ammonia and nitrite. This paper describes several types of flow injection mechanisms used in commercial fluidized-sand biofilters and provides criteria for design of flow distribution mechanisms at the

Steven T. Summerfelt

2006-01-01

140

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.

2014-06-16

141

Sand for Traction  

USGS Multimedia Gallery

Steam engines used high-grade silica sand for traction on the rails. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially...

142

Contribution of aeolian sand to backbarrier marsh sedimentation  

NASA Astrophysics Data System (ADS)

The frequency of island overwash is commonly assumed to be the main factor regulating sand flux to backbarrier marshes; however, aeolian transport of sand across a barrier has received little attention in saltmarsh research. The contribution of aeolian sand to backbarrier marshes is examined here with marsh cores and measurements of wind-blown sediment transport across transgressive and regressive parts of a barrier island. Backbarrier marshes fronted by a wide washover fan or a high-elevation dune ridge were supplied with aeolian sand that significantly contributed to vertical accretion, especially near the marsh - barrier island edge. The percent volume of the marsh originating from aeolian sand, based on the upper 1 cm of marsh sediment, decreased by an order of magnitude only ˜20 m from the dune - marsh boundary. Sandy beds sampled in every marsh core at depth are composed of aeolian sand and were likely emplaced over time after storms deposited a sandy washover fan near the marsh and/or reduced vegetation cover across the island. Sand beds preserved within backbarrier marsh deposits are commonly thought to have been emplaced rapidly during a storm; however, post-storm aeolian transport should also be considered as an important mechanism for forming sand beds over a longer period of time within saltmarsh strata. The contribution of aeolian sand to backbarrier marsh accretion should increase as sea level continues to rise causing many barrier islands to narrow thereby reducing transport distances between the dune and marsh. Along developed coastlines, however, anthropogenic factors associated with increased development largely decrease the connectivity between the dunes and backbarrier marsh.

Rodriguez, Antonio B.; Fegley, Stephen R.; Ridge, Justin T.; VanDusen, Beth M.; Anderson, Noel

2013-01-01

143

The Unified Gravel-Sand (TUGS) Model: Simulating the Transport of Gravel-Sand Mixtures in Rivers  

NASA Astrophysics Data System (ADS)

TUGS Model was developed by employing the surface-based bedload equation of Wilcock and Crowe (2003) and linking grain size distributions in the bedload, surface layer, and subsurface sediment deposit with the gravel transfer function of Hoey and Ferguson (1994) and Toro-Escobar et al. (1996), and a hypothetical sand transfer function. The unmodified model was applied to simulate the sedimentation process in Marmot Reservoir, Sandy River, Oregon and produced similar stratified sediment deposit as observed through coring exercises. The model was also examined with three runs of large-scale flume experiments conducted at St. Anthony Falls Laboratory (SAFL) by Seal et al. (1995). With a very minor modification to Wilcock and Crowe (2003) equation, the model excellently reproduced the longitudinal profiles, gravel grain size distributions and sand fractions in the deposits for all the three SAFL runs. Following its examination, TUGS model was applied to simulate the sediment transport dynamics in the Sandy River, Oregon under a few hypothetical scenarios, focusing on the dynamics of sand fractions in gravel-bedded channel deposits. Results of the exploratory runs on the Sandy River indicate that (a) surface and subsurface sand fractions generally increase in the downstream direction, similar to observed in the field; (b) sand fraction in the deposit is positively correlated with sand supply as expected; (c) extremely high sand supply under similar gravel supply and hydrologic conditions can transform the river into predominantly sand-bedded; (d) increased discharge under the same sand and gravel supply conditions results in decreased sand fraction in the deposit as expected; and (e) there can be significant increase in surface and subsurface sand fractions in the backwater zones near the mouth of the river as expected.

Cui, Y.

2006-12-01

144

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

145

Numerical modeling of wind-blown sand on Mars.  

PubMed

Recent observation results show that sand ripples and dunes are movable like those on Earth under current Martian climate. And the aeolian process on Mars therefore is re-attracting the eyes of scientific researchers in different fields. In this paper, the spatial and temporal evolution of wind-blown sand on Mars is simulated by the large-eddy simulation method. The simulations are conducted under the conditions of both friction wind speed higher and lower than the "fluid threshold", respectively. The fluid entrainment of the sand particles, the processes among saltation sand particles and sand bed, and the negative feedback of sand movement to flow field are considered. Our results show that the "overshoot" phenomenon also exists in the evolution of wind-blown sand on Mars both temporally and spatially; impact entrainment affects the sand transport rate on Mars when the wind speed is smaller or larger than the fluid threshold; and both the average saltation length and height are one order of magnitudes larger than those on Earth. Eventually, the formulas describing the sand transport rate, average saltation length and height on Mars are given, respectively. PMID:25236498

Huang, HaoJie; Bo, TianLi; Zheng, XiaoJing

2014-09-01

146

Trajectories of saltating sand particles behind a porous fence  

NASA Astrophysics Data System (ADS)

Trajectories of aeolian sand particles behind a porous wind fence embedded in a simulated atmospheric boundary layer were visualized experimentally, to investigate the shelter effect of the fence on sand saltation. Two sand samples, one collected from a beach (d = 250 ?m) and the other from a desert (d = 100 ?m), were tested in comparison with the previous studies of a 'no-fence' case. A wind fence (? = 38.5%) was installed on a flat sand bed filled with each sand sample. A high-speed photography technique and the particle tracking velocimetry (PTV) method were employed to reconstruct the trajectories of particles saltating behind the fence. The collision processes of these sand particles were analyzed, momentum and kinetic energy transfer between saltating particles and ground surface were also investigated. In the wake region, probability density distributions of the impact velocities agree well with the pattern of no-fence case, and can be explained by a log-normal law. The horizontal component of impact velocity for the beach sand is decreased by about 54%, and about 76% for the desert sand. Vertical restitution coefficients of bouncing particles are smaller than 1.0 due to the presence of the wind fence. The saltating particles lose a large proportion of their energy during the collision process. These results illustrate that the porous wind fence effectively abates the further evolution of saltating sand particles.

Zhang, Ning; Lee, Sang Joon; Chen, Ting-Guo

2015-01-01

147

Morphology and controls on the position of a gravel-sand transition: Fraser River, British Columbia  

NASA Astrophysics Data System (ADS)

river channels often exhibit a relatively abrupt transition from gravel- to sand-bedded conditions. The phenomenon is well documented, but few prior studies have analyzed the spatial variability through reaches where transitions occur. The downstream fining pattern observed in the Fraser River is cited as a classic example of an abrupt gravel-sand transition in a large alluvial channel. However, important questions regarding the exact location of the transition, its sedimentology and morphology, and what controls its location remain unanswered. Here we present observations of the downstream change in bed material grain size, river bed topography, and channel hydraulics through the reach within which the transition occurs. These observations indicate that the gravel-sand transition is characterized by a terminating gravel wedge, but there are patches of gravel downstream of the wedge forming a diffuse extension. We show that there is a dramatic decrease in shear stress at the downstream end of the wedge and a consequent cessation of general gravel mobility. We argue that the patches of gravel observed beyond the wedge are the result of enhanced mobility of fine gravel over a sand bed. We also find that sand in suspension declines rapidly at the downstream end of the wedge, suggesting that sand is delivered to the bed, completing the sedimentary conditions for a gravel-sand transition. We propose that the break in river slope associated with the transition is a consequential feature of the transition.

Venditti, Jeremy G.; Church, Michael

2014-09-01

148

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

149

Surviving Bed Rest  

MedlinePLUS

... duration of your bed rest. Continue How Does Bed Rest Help? Women with pregnancy conditions related to ... What Can — and Can't — You Do on Bed Rest? Sometimes, doctors recommend modified bed rest or " ...

150

Industrial sand and gravel  

USGS Publications Warehouse

In 2005, domestic production of industrial sand and gravel was about 31 Mt, a 5% increase from 2004. This increase was bouyed by robust construction and petroleum sectors of the US economy. Based on estimated world production figures, the United States was the world's leading producer and consumer of industrial sand and gravel. In the short term, local shortages of industrial sand and gravel will continue to increase.

Dolley, T.P.

2006-01-01

151

Petrology and Bulk Chemistry of Modern Bed Load Sediments From Rivers Draining the Eastern Tibetan Plateau  

NASA Astrophysics Data System (ADS)

We studied river bed load petrology and bulk sediment chemistry of the headwaters of the Changjiang, Huang He and Red rivers in China and Vietnam. These rivers drain the eastern and southeastern parts of the Tibetan Plateau which includes part of the Indian-Eurasian suture zone. The eastern Tibetan Plateau is dominated by marine sedimentary rocks with a few scattered intrusive igneous outcrops, while the suture zone is characterized by a mixture of high-grade metamorphic, ultramafic, granitic, volcanic arc and marine sedimentary rocks. The arithmetic average for Qt: Ft: Rft along the suture zone varies from 56:2:42 along the Red River Fault (RRF) zone to 38:6:56 in the interior of the continent, while sands from rivers draining the plateau average 32:8:60. The sands analyzed in this study are relatively immature compared to most data available from most rivers in the tropics. The average Chemical Index of Alteration (CIA) for samples from the RRF suture zone (0.62) is similar to that of rivers draining other tropical regions like the Niger, Chao Phraya, Mekong, Ganges, Amazon and Brahmaputra. The CIA values from the RRF zone are also significantly different from the rest of the suture zone (0.36) and the plateau area (0.38). The difference can be attributed to the combined effect of relief and precipitation. The RRF lies in the Red River drainage and receives ˜1820 mm of precipitation annually, while the plateau area averages ˜620 mm annually. In the case of the Red River drainage, the relief combined with higher humidity can increase physical weathering and reduce the residence time of sediment in the river drainage, therefore, continuously replacing the sediment transported out of the drainage by freshly weathered immature materials. In the plateau area, lower precipitation and runoff may limit sediment transport and chemical weathering leading to sediment immaturity.

Borges, J. B.

2003-12-01

152

Fluid-bed heat-exchanger optimization and bed materials selection. Final report  

SciTech Connect

A study was undertaken to evaluate the effect of material properties on heat exchanger costs for waste gas streams from 500 to 3000/sup 0/F. 400, 800, 1200, and 1600/sup 0/F bed temperatures were used. The cost of the major heat exchanger components was identified and related directly to bed material properties. The overall heat exchanger costs were determined and used in a comparative analysis to assess the merit of each material. Two hundred materials were reviewed: metals, alloys, oxides, minerals, carbides, borides, intermetallics, and cermets. Compared to the lowest cost heat exchanger based on the best bed material, at 400/sup 0/F, the cost of the heat exchanger for sand is 14% higher; at 800/sup 0/F, 29% higher; at 1200/sup 0/F, 23% higher, and at 1600/sup 0/F, 25% higher. In comparing the heat transfer performance at 400/sup 0/F, the sand bed had a 50% lower heat transfer coefficient compared to the top performer, resulting in 62% more heat transfer surface area. The general trend showed that the oxides and minerals were the most cost effective at the lower bed temperatures and the metallic bed materials at the higher bed temperature.

Not Available

1981-02-01

153

Total sand inputFine nose Non-equilibrium tail Equilibrium tail  

E-print Network

jump. Sand (D50 = 424 um) was added to the recirculating water by conveyor feed. This washed through). The coin (a British penny) is 20 mm diameter. Figure 1b: Transition between fine bed nose and coarse (fig. 4) in three lower beds. The coin is 20 mm diameter. Figure 1d: Photograph of adjacent panel

Watson, Andrew

154

Forces encountered by a sphere during impact into sand  

NASA Astrophysics Data System (ADS)

We describe direct measurements of the acceleration of an object impacting on a loosely packed granular bed under various pressures, using an instrumented sphere. The sphere acts as a noninvasive probe that measures and continuously transmits the acceleration as it penetrates into the sand, using a radio signal. The time-resolved acceleration of the sphere reveals the detailed dynamics during the impact that cannot be resolved from the position information alone. Because of the unobstructed penetration, we see a downward acceleration of the sphere at the moment the air cavity collapses. The compressibility of the sand bed is observed through the oscillatory behavior of the acceleration curve for various ambient pressures; it shows the influence of interstitial air on the compaction of the sand as a function of time.

Joubaud, Sylvain; Homan, Tess; Gasteuil, Y.; Lohse, Detlef; van der Meer, Devaraj

2014-12-01

155

Aeolian sand transport: Experiment and Theory  

NASA Astrophysics Data System (ADS)

Experiments on aeolian sand transport were carried out in a wind tunnel at the University of Aarhus in Denmark for a wide range of wind speeds. The saltating particles were analyzed using imaging techniques (PIV and PTV). Vertical profiles of particle concentration and velocity were extracted. The particle concentration was found to decrease exponentially with the height above the bed and the characteristic decay height was independent of the wind speed (Creyssels et al., 2009). In contrast with the logarithmic profile of the wind speed, the particle velocity was found to vary linearly with the height. In addition, the particle slip velocity is finite and invariant with the wind speed. These results are shown to be closely related to the features of the splash function that characterizes the impact of the saltating particles onto a sand bed. A numerical simulation was developed that explicitly incorporates low velocity moments of the splash function in a calculation of the boundary conditions that apply at the bed (Creyssels et al., 2009). The overall features of the experimental measurements are well reproduced by the simulation. Reference: M. Creyssels, P. Dupont, A. Ould el Moctar, A. Valance, I. Cantat, J. T. Jenkins, J. M. Pasini and K. R. Rasmussen, J. Fluid Mech. 625, 47 (2009).

Valance, A.; Ould Eld Moctar, A.; Dupont, P.; Cantat, I.; Jenkins, J.

2010-05-01

156

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

157

Permeability of shaly sands  

NASA Astrophysics Data System (ADS)

The permeability of a sand shale mixture is analyzed as a function of shale fraction and the permeability of the two end-members, i.e., the permeability of a clay-free sand and the permeability of a pure shale. First, we develop a model for the permeability of a clay-free sand as a function of the grain diameter, the porosity, and the electrical cementation exponent. We show that the Kozeny-Carman-type relation can be improved by using electrical parameters which separate pore throat from total porosity and effective from total hydraulic radius. The permeability of a pure shale is derived in a similar way but is strongly dependent on clay mineralogy. For the same porosity, there are 5 orders of magnitude of difference between the permeability of pure kaolinite and the permeability of pure smectite. The separate end-members' permeability models are combined by filling the sand pores progressively with shale and then dispersing the sand grains in shale. The permeability of sand shale mixtures is shown to have a minimum at the critical shale content at which shale just fills the sand pores. Pure shale has a slightly higher permeability. Permeability decreases sharply with shale content as the pores of a sand are filled. The permeability of sand shale mixtures thus has a very strong dependence on shale fraction, and available data confirm this distinctive shale-fraction dependence. In addition, there is agreement (within 1 order of magnitude) between the permeabilities predicted from our model and those measured over 11 orders of magnitude from literature sources. Finally, we apply our model to predict the permeabilities of shaly sand formations in the Gulf Coast. The predictions are compared to a data set of permeability determination made on side-wall cores. The agreement between the theoretical predictions and the experimental data is very good.

Revil, A.; Cathles, L. M.

1999-03-01

158

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

159

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

160

The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step  

NASA Astrophysics Data System (ADS)

Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency, positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than further downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

Schmeeckle, M. W.

2014-07-01

161

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 ...

162

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 ...

163

Design and Operation of Fluid Beds for Heating, Cooling and Quenching Operations  

E-print Network

A commercial foundry has been established which makes extensive use of fluid beds in the production of heat treated alloy steel castings. The castings are cooled immediately after solidification by fluidizing the mold sand in which they were cast...

Kemp, W. E.

1981-01-01

164

Industrial sand and gravel  

USGS Publications Warehouse

Domestic production of industrial sand and gravel in 2009 was about 27 Mt (30 million st), declining by 10 percent compared with 2008. Certain end uses of industrial sand and gravel, such as foundry and glassmaking sand, may have declined by a factor greater than 10 percent in 2009. U.S. apparent consumption was 24.7 Mt (27.2 million st) in 2009, down by 10 percent from the previous year, and imports declined to 83 kt (91,000 st).

Dolley, T.P.

2010-01-01

165

Hydraulic Fracturing Sand  

USGS Multimedia Gallery

Fine-grained silica sand is mixed with chemicals and water before being pumped into rock formations to prevent the newly created artificial fractures from closing after hydraulic fracturing is completed....

166

Sand, Plants and Pants  

NSDL National Science Digital Library

In this activity, learners explore how the application of nano-sized particles or coatings can change a bigger materialâs properties. Learners investigate the hydrophobic properties of plants, nano-fabric pants and magic sand.

Network, Nanoscale I.; Houston, Children'S M.

2014-06-04

167

Sand boils without earthquakes  

USGS Publications Warehouse

Sedimentary deformation caused by liquefaction has become a popular means for inferring prehistoric strong earthquakes. This report describes a new mechanism for generating such features in the absence of earthquakes. Sand boils and a 180-m-long sand dike formed in Fremont Valley, California, when sediment-laden surface runoff was intercepted along the upslope part of a 500-m-long preexisting ground crack, flowed subhorizonally in the crack, and then flowed upward in the downslope part of the crack where it discharged as sand boils on the land surface. If the sand boils and their feeder dike were stratigraphically preserved, they could be misinterpreted as evidence for earthquake-induced liquefaction. -Authors

Holzer, T.L.; Clark, M.M.

1993-01-01

168

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.

169

North Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-417, 10 July 2003

The martian north polar ice cap is surrounded by fields of dark, windblown sand dunes. This March 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dunes near 76.5oN, 264.7oW. The steep dune slip faces indicate wind transport of sand from the lower left toward the upper right. Sunlight illuminates the scene from the lower left.

2003-01-01

170

Sand Volcano Following Earthquake  

NASA Technical Reports Server (NTRS)

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) in the October 17, 1989, Loma Prieta earthquake. Vented sand contains marine-shell fragments. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: J.C. Tinsley, U.S. Geological Survey)

1989-01-01

171

Fluidized bed viscosity measurements in reduced gravity  

SciTech Connect

The understanding of fluidized characteristics of solid particles is a major challenge in the prediction of many technological processes in numerous commercial industries including chemical, petroleum, agricultural, pharmaceutical, metallurgical, plastics, and food processing. Fluidized bed viscosity was studied experimentally in a series of reduced gravity parabolic flights aboard NASA`s KC-135 aircraft. Silica sands of two different size distributions were fluidized by air. The experimental set up incorporated instrumentation to measure the air flow rate, the pressure drop and the apparent viscosity of the fluidized sand at the wide range of the shear rate. The fluidization chamber had transparent walls to allow visualization of the structure changes involved in fluidization in reduced gravity. Experiments were performed over a broad range of gravitational accelerations including microgravity and double gravity conditions. The results of the flight and ground experiments reveal significant differences in the apparent viscosity of fluidized sand and overall void factor in microgravity as compared to one-g conditions.

Bakhtiyarov, S.I.; Overfelt, R.A. [Auburn Univ., AL (United States). Space Power Inst.

1997-12-31

172

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

Microsoft Academic Search

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}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

Javier Gil; Miguel A. Caballero; J. A. Martin; María-Pilar Aznar; José Corella

1999-01-01

173

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

174

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

175

Non-dune eolian sand in Indian mounds  

NASA Astrophysics Data System (ADS)

Indian mounds, near Careyville, Florida, about 2.0 m high, are located on hillsides and hilltops 10 to 20 m above the floodplain of the nearest river (Choctawhatchee). Each mound is composed largely of quartz sand, with a scattering of artefacts and stream pebbles (not in layers), but with no visible bedding. Probability plots showed 25 Gaussian distributions, 18 having the 'dune hump', three having the 'surf break' and nine being doubly-truncated or having other patterns of unknown or uncertain origin. The surf breaks probably were inherited from pre-Pleistocene marine terraces in the area. The pebbles and the sand were not introduced by the same agency. The sand probability plots, taken as a set, indicate an eolian origin. The rough symmetry of the mounds, and the lack of cross-bedding, argue against a migrating dune origin. On a variability plot (showing the variability of the means versus the variability of the standard deviations), one suite of samples fell clearly within the 'dune' number field, a second suite in the overlap area between 'dune' and 'beach', and a third suite, taken immediately adjacent to a creek bed, plotted in the overlap area between 'beach' and 'coastal plain stream'. The pebbles, of common Southern Appalachian types, are attributed to the activities of the inhabitants, perhaps children. The sand is thought to have been carried by the wind, perhaps from nearby river sand bars, or from areas burned either by lightning-set wildfires or as part of "slash-and-burn" agriculture. The mounds are thought to represent clearings (for huts), and hence good trapping devices for wind-borne sand.

Tanner, William F.

1980-02-01

176

Early stages in biofilm development in methanogenic fluidized-bed reactors  

Microsoft Academic Search

Biofilm development in methanogenic fluidized-bed reactors with sand as the carrier was studied on a laboratory scale. The microorganisms present in consecutive layers of the biofilm of mature sludge granules were preliminarily characterized on the basis of their morphology, element composition and adhesion capacity and were compared to bacteria which take part in the initial colonization of sand. The early

Anne M. Lauwers; Wolfgang Heinen; Leon G. M. Gorris; Chris van der Drift

1990-01-01

177

Influence of Ephemeral Sand Islands in a Large Prairie River on Diversity and Density of Benthic Macroinvertebrates  

Microsoft Academic Search

The ecology of prairie rivers has rarely been investigated, with most aquatic studies focusing on reservoirs or intermittent streams. The Kansas River, a sand-bed river draining a watershed historically composed primarily of tallgrass and mixed grass prairie, contains in its channel numerous ephemeral sand-bar islands. Recent riverine research on relatively permanent, forested islands has shown a strong correlation between community

J. M. Kreft; S. L. Moore; J. H. Thorp

2005-01-01

178

Incident Angle of Saltating Particles in Wind-Blown Sand  

PubMed Central

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

179

Evaluation of fluid bed heat exchanger optimization parameters. Final report  

SciTech Connect

Uncertainty in the relationship of specific bed material properties to gas-side heat transfer in fluidized beds has inhibited the search for optimum bed materials and has led to over-conservative assumptions in the design of fluid bed heat exchangers. An experimental program was carried out to isolate the effects of particle density, thermal conductivity, and heat capacitance upon fluid bed heat transfer. A total of 31 tests were run with 18 different bed material loads on 12 material types; particle size variations were tested on several material types. The conceptual design of a fluidized bed evaporator unit was completed for a diesel exhaust heat recovery system. The evaporator heat transfer surface area was substantially reduced while the physical dimensions of the unit increased. Despite the overall increase in unit size, the overall cost was reduced. A study of relative economics associated with bed material selection was conducted. For the fluidized bed evaporator, it was found that zircon sand was the best choice among materials tested in this program, and that the selection of bed material substantially influences the overall system costs. The optimized fluid bed heat exchanger has an estimated cost 19% below a fin augmented tubular heat exchanger; 31% below a commercial design fluid bed heat exchanger; and 50% below a conventional plain tube heat exchanger. The comparisons being made for a 9.6 x 10/sup 6/ Btu/h waste heat boiler. The fluidized bed approach potentially has other advantages such as resistance to fouling. It is recommended that a study be conducted to develop a systematic selection of bed materials for fluidized bed heat exchanger applications, based upon findings of the study reported herein.

Not Available

1980-03-01

180

Direct numerical simulations of aeolian sand ripples.  

PubMed

Aeolian sand beds exhibit regular patterns of ripples resulting from the interaction between topography and sediment transport. Their characteristics have been so far related to reptation transport caused by the impacts on the ground of grains entrained by the wind into saltation. By means of direct numerical simulations of grains interacting with a wind flow, we show that the instability turns out to be driven by resonant grain trajectories, whose length is close to a ripple wavelength and whose splash leads to a mass displacement toward the ripple crests. The pattern selection results from a compromise between this destabilizing mechanism and a diffusive downslope transport which stabilizes small wavelengths. The initial wavelength is set by the ratio of the sediment flux and the erosion/deposition rate, a ratio which increases linearly with the wind velocity. We show that this scaling law, in agreement with experiments, originates from an interfacial layer separating the saltation zone from the static sand bed, where momentum transfers are dominated by midair collisions. Finally, we provide quantitative support for the use of the propagation of these ripples as a proxy for remote measurements of sediment transport. PMID:25331873

Durán, Orencio; Claudin, Philippe; Andreotti, Bruno

2014-11-01

181

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

182

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

183

RETRACTED: The influence of sand diameter and wind velocity on sand particle lift-off and incident angles in the windblown sand flux  

NASA Astrophysics Data System (ADS)

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy) This article has been retracted at the request of This article has been retracted at the request of the Editors-in-Chief. This article also contains significant similarity with parts of text, written by the same author(s), that have appeared in Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, The influence of wind velocity and sand grain diameter on the falling velocities of sand particles, Powder Technology, Volume 241, June 2013, Pages 158-165. Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, Analysis of sand particles' lift-off and incident velocities in wind-blown sand flux, Acta Mechanica Sinica, April 2013, Volume 29, Issue 2, pp 158-165. Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, Influence of sand grain diameter and wind velocity on lift-off velocities of sand particles, The European Physical Journal E, May 2013, 36:50. Tian-Li Bo, Shao-Zhen Duan, Xiao-Jing Zheng, Yi-Rui Liang, The influence of sand bed temperature on lift-off and falling parameters in windblown sand flux, Geomorphology, Volume 204, 1 January 2014, Pages 477-484. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

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

2013-05-01

184

Catalytic Pyrolysis of Oak via Pyroprobe and Bench Scale, Packed Bed Pyrolysis Reactors  

Technology Transfer Automated Retrieval System (TEKTRAN)

The pyrolytic conversion of oak sawdust at 500°C in flowing He over eight proprietary catalysts is described and compared to the control bed material, quartz sand. The reactions were conducted and compared in two reactors, an analytical, ug-scale pyroprobe reactor and a bench, g-scale packed bed re...

185

Gas cleaning for IC engine applications from fixed bed biomass gasification  

Microsoft Academic Search

Gas cleaning for tar and particle removal is necessary for internal combustion (IC) engine applications of producer gas from fixed bed biomass gasifiers which are usually in the capacity range from 100 kW up to 5000 kW. In the present investigation, tar and particle collection efficiencies have been determined in a sand bed filter, a wash tower, two different fabric

P. Hasler; Th. Nussbaumer

1999-01-01

186

Panel Bed Filters for Simultaneous Removal of Fly Ash and Sulfur Dioxide  

Microsoft Academic Search

Experimental studies of the filtration of dilute aerosols of Dow microspheres by beds of sand have been conducted with flows passing vertically upward, vertically downward, and horizontally. With the use of Happel’s “free surface” model for a granular bed, the results can be correlated reasonably well by semiempirical, semitheoretical considerations taking into account collection by diffusion, gravity settling, direct interception,

Leon Paretsky; Louis Theodore; Robert Pfeffer; Arthur M. Squires

1971-01-01

187

Multifuel bubbling bed fluidized bed combustor system  

SciTech Connect

Apparatus for generating heat is described, comprising: a fluidized bed pyrolyzer; a fluidized bed combustor; a combustor vessel; means for supporting a combustor bed of granular material within the combustor vessel; means for adding the gaseous effluents removed from the pyrolyzer bed to the combustor bed; means for adding granular material to the combustor bed; means for removing gaseous effluents from the combustor vessel; means for removing bed material from the combustor; a heat exchanger comprising a vessel; means for adding gaseous effluents to, and means for removing gaseous effluents from, the heat exchanger vessel, and means for adding an exchange coolant to, and means for removing an exchange coolant from, the heat exchanger vessel; particulate collector means connected to the heat exchanger for removing particulate matter from the gaseous effluents removed from the heat exchanger; and stack means connected to the particulate collector for releasing the gaseous effluents removed from the heat exchanger to the atmosphere.

Wormer, A.F.

1989-04-25

188

Frosted Sand Dunes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] (Released 22 July 2002) This image, located near 79.6 N and 142.7 E, displays sand dunes covered in CO2 frost. This is a region of Mars that contains circumpolar sand seas. The large sand deposits and the high winds that circulate around the pole allow for the formation of a huge dune field that surrounds the north polar cap. As the northern hemisphere progresses towards winter, CO2 frost condenses out of the atmosphere and covers the dunes. During northern spring, the CO2 sublimates and the dunes are once again uncovered and active. This image was taken as northern spring progresses and the crests of the dunes are just starting to be exposed. The dark dune material absorbs sunlight more efficiently than the brighter frost, aiding in the sublimation of the remaining frost.

2002-01-01

189

Ganges Chasma Sand Sheet  

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.

Today's sand sheet is located in the Ganges Chasma portion of Valles Marineris. As with yesterday's image, note that the dune forms are seen only at the margin and that the interior of the sand sheet at this resolution appears to completely lack dune forms.

Image information: VIS instrument. Latitude -6.4, Longitude 310.7 East (49.3 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

190

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

191

Sand Dunes with Frost  

NASA Technical Reports Server (NTRS)

9 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of frost-covered sand dunes in the north polar region of Mars in early spring, 2004. The dunes indicate wind transport of sand from left to right (west to east). These landforms are located near 78.1oN, 220.8oW. This picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.

2004-01-01

192

Windblown Sand in Briault  

NASA Technical Reports Server (NTRS)

17 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows low, broad sand dunes and sheets in southern Briault Crater near 10.1oS, 270.7oW. In this case, winds have swept up all available sand in Briault Crater, and moved it toward the south side of the basin. The wind streak pattern of these landforms indicates that the dominant winds blow from the north (top) toward the south. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.

2004-01-01

193

Laboratory measurement of bottom shear stress on a movable bed  

Microsoft Academic Search

A shear plate was developed to obtain direct measurements of bottom shear stress under nonbreaking surface gravity waves on a movable sand bed. The experiments were conducted under regular wave conditions in a large wave tank where time histories of bottom shear stress and surface elevation were obtained from a shear plate and wave gauges. Measurements were made at scales

Kelly L. Rankin; Richard I. Hires

2000-01-01

194

Biomass gasification: Produced gas upgrading by in-bed use of dolomite  

Microsoft Academic Search

When some calcined dolomite (OCa·OMg) is used in the bed of a biomass gasifier of fluidized bed type the raw gas produced is cleaner than when only silica sand is used in it as fluidizing medium. In-bed dolomite changes the product distribution at the gasifier exit because of in-situ catalytic reactions promoted by the calcined dolomite. Gasifying with steam-Oâ mixtures

Ana Olivares; María P. Aznar; Miguel A. Caballero; Javier Gil; E. Frances; José Corella

1997-01-01

195

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

196

Sand Hill Rd. Junipero Serra  

E-print Network

Alpine 280 101 Campus Drive Sand Hill Rd. University Palm StockFarm Junipero Serra Page Mill Oregon Floor, South Wing right next to Peet's Coffee. Directions from 280 North or South - Exit Sand Hill Rd

Stanford University

197

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

198

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

199

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

200

Heavy Oil and Oil (Tar) Sands in North America: An Overview & Summary of Contributions  

Microsoft Academic Search

As conventional oil and gas reservoirs become depleted other unconventional energy sources have to be recovered and produced.\\u000a Four of the major unconventional resources that are strategic for North American interests are heavy oil, oil sands, oil shales,\\u000a and coal-bed methane. Recent interest and activity in Canada’s vast oil sands are progressing rapidly as soaring oil prices\\u000a are fueling a

Frances J. Hein

2006-01-01

201

A Multiphase First Order Model for Non-Equilibrium Sand Erosion, Transport and Sedimentation  

E-print Network

Three phenomena are involved in sand movement: erosion, wind transport, and sedimentation. This paper presents a comprehensive easy-to-use multiphase model that include all three aspects with a particular attention to situations in which erosion due to wind shear and sedimentation due to gravity are not in equilibrium. The interest is related to the fact that these are the situations leading to a change of profile of the sand bed.

Preziosi, Luigi; Bruno, Luca

2015-01-01

202

Sound-Producing Sand Avalanches  

Microsoft Academic Search

Sound-producing sand grains constitute one of nature's more puzzling and least understood physical phenomena. They occur naturally in two distinct types: booming and squeaking sands. Although both varieties of sand produce unexpectedly pure acoustic emissions when sheared, they diΠer in their frequency range and duration of emission, as well as the environment in which they tend to be found.

Paul Sholtz; Michael Bretz; Franco Nori

1996-01-01

203

Is promise of Alberta's tar sands nearing reality  

SciTech Connect

Alberta's far north shares a vital element with Saudi Arabia: Many hundreds of billions of barrels of oil. The Energy Resources and Conservation Board counts one trillion barrels, four to five times above Saudi Arabia's reserves. To date, though, it has not been economic to tap these reserves, which are in the form of tar sands. Now, however, a new process, proven at the pilot stage, finally may transform these resources into a possible competitor to OPEC. Its unpronounceable acronym, SAGD, stands for steam-assisted gravity drainage. The SAGD technique involves a couple of major innovations. First, it reverses the traditional approach. Instead of mining the sands from the surface downward, the systems developed and proven by the Alberta Oil Sands Technology and Research Authority (AOSTRA) starts from the bottom up. The oil is produced from underneath the bedded tar sands. Second, the system is intrinsically small scale. It does not rely upon megaprojects to try to realize economies of scale. The earlier surface-mining projects were sized at 100,000-200,000 barrels per day (b/d). In contrast, the optimum economic scale of the SAGD system is roughly 30,000 b/d, making it a more manageable and less risky technology. SAGD involves the marriage of conventional shaft and tunnel mining with the new precision possible in horizontal drilling. The cost savings are dramatic, and the environmental insult from the operation is greatly reduced. Instead of stripping overburden and then strip-mining the tarry sands, the SAGD technique starts underground with tunnels drilled beneath the tar sands strata. From the tunnels, pairs of horizontal wells are drilled up into the beds. Steam injected into the upper well fluidizes the tar, creating a void, from which the liquid tar flows down into the lower producing well.

Stauffer, T.

1993-10-15

204

Hybrid fluidized bed combuster  

SciTech Connect

A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.

Kantesaria, Prabhudas P. (Windsor, CT); Matthews, Francis T. (Poquonock, CT)

1982-01-01

205

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

206

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

207

Dark Sand Dunes  

NASA Technical Reports Server (NTRS)

13 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes in the north polar region of Mars. The dominant winds responsible for these dunes blew from the lower left (southwest). They are located near 76.6oN, 257.2oW. The picture covers an area 3 km (1.9 mi) across; sunlight illuminates the scene from the upper right.

2005-01-01

208

Moving sand dunes  

E-print Network

In several desert areas, the slow motion of sand dunes can be a challenge for modern human activities and a threat for the survival of ancient places or archaeological sites. However, several methods exist for surveying the dune fields and estimate their migration rate. Among these methods, the use of satellite images, in particular of those freely available on the World Wide Web, is a convenient resource for the planning of future human settlements and activities.

Sparavigna, Amelia Carolina

2011-01-01

209

Fluidized Bed Asbestos Sampler Design and Testing  

SciTech Connect

A large number of samples are required to characterize a site contaminated with asbestos from previous mine or other industrial operations. Current methods, such as EPA Region 10’s glovebox method, or the Berman Elutriator method are time consuming and costly primarily because the equipment is difficult to decontaminate between samples. EPA desires a shorter and less costly method for characterizing soil samples for asbestos. The objective of this was to design and test a qualitative asbestos sampler that operates as a fluidized bed. The proposed sampler employs a conical spouted bed to vigorously mix the soil and separate fine particulate including asbestos fibers on filters. The filters are then analyzed using transmission electron microscopy for presence of asbestos. During initial testing of a glass prototype using ASTM 20/30 sand and clay fines as asbestos surrogates, fine particulate adhered to the sides of the glass vessel and the tubing to the collection filter – presumably due to static charge on the fine particulate. This limited the fines recovery to ~5% of the amount added to the sand surrogate. A second prototype was constructed of stainless steel, which improved fines recovery to about 10%. Fines recovery was increased to 15% by either humidifying the inlet air or introducing a voltage probe in the air space above the sample. Since this was not a substantial improvement, testing using the steel prototype proceeded without using these techniques. Final testing of the second prototype using asbestos suggests that the fluidized bed is considerably more sensitive than the Berman elutriator method. Using a sand/tremolite mixture with 0.005% tremolite, the Berman elutriator did not segregate any asbestos structures while the fluidized bed segregated an average of 11.7. The fluidized bed was also able to segregate structures in samples containing asbestos at a 0.0001% concentration, while the Berman elutriator method did not detect any fibers at this concentration. Opportunities for improvement with the fluidized bed include improving reproducibility among replicates, increasing mass recovery, improving the lid gasket seal.

Karen E. Wright; Barry H. O'Brien

2007-12-01

210

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 ...

211

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

212

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...

213

Space Radar Image of Namibia Sand Dunes  

NASA Technical Reports Server (NTRS)

This spaceborne radar image shows part of the vast Namib Sand Sea on the west coast of southern Africa, just northeast of the city of Luderitz, Namibia. The magenta areas in the image are fields of sand dunes, and the orange area along the bottom of the image is the surface of the South Atlantic Ocean. The region receives only a few centimeters (inches) of rain per year. In most radar images, sandy areas appear dark due to their smooth texture, but in this area the sand is organized into steep dunes, causing bright radar reflections off the dune 'faces.' This effect is especially pronounced in the lower center of the image, where many glints of bright radar reflections are seen. Radar images of this hyper-arid region have been used to image sub-surface features, such as abandoned stream courses. The bright green features in the upper right are rocky hills poking through the sand sea. The peninsula in the lower center, near Hottentott Bay, is Diaz Point; Elizabeth Point is south of Diaz Point. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 11, 1994. The image is 54.2 kilometers by 82.2 kilometers (33.6 miles by 51.0 miles) and is centered at 26.2 degrees South latitude, 15.1 degrees East longitude. North is toward the upper left. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted, horizontally received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

1994-01-01

214

Red Rock Crab in Puget Sound  

USGS Multimedia Gallery

A Red Rock Crab (Romaleon antennarium) captured in a beach seine during a 2012 Bainbridge Island larval forage fish survey.  This survey focused on the abundance, habitat use, and food habits of larval forage fish (surf smelt and sand lance) and was conducted by scientists from...

215

MISO Market Performance: An AgentMISO Market Performance: An Agent--Based Computational TestBased Computational Test--BedBed HongyanHongyan LiLiaa, andand LeighLeigh TesfatsionTesfatsionbb  

E-print Network

TestBased Computational Test--BedBed HongyanHongyan LiLiaa, andand LeighLeigh Tesfatsion Initial Learning Calibration Experiments: GenCo "Sweet Spot" Learning (red highest net earnings is a wholesale power market test bed populated by interacting software "agents." AMES means Agent-based Modeling

Tesfatsion, Leigh

216

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.

217

Regional implications of an extensive linear sediment-dispersal system along western margin of Cretaceous interior seaway: Second Wall Creek sand, Powder River basin, Wyoming  

Microsoft Academic Search

The Second Wall Creek sand in the Powder River basin in Johnson and Natrona Counties is similar in clast lithology, primary sedimentary structures, and facies association to the Torchlight Sandstone at the top of the Frontier Formation in the northern Big Horn basin. The Second Wall Creek sand is predominantly composed of medium to coarse-grained, moderately sorted massive to cross-bedded

C. F. Vondra; N. I. Khandaker

1988-01-01

218

Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation  

Microsoft Academic Search

This paper concludes that back diffusion from one or a few thin clayey beds in a sand aquifer can cause contaminant persistence above MCLs in a sand aquifer long after the source zone initially causing the plume is isolated or removed. This conclusion is based on an intensive case study of a TCE contaminated site in Florida, with the processes

Beth L. Parker; Steven W. Chapman; Martin A. Guilbeault

2008-01-01

219

Downstream patterns of bed material grain size in a large, lowland alluvial river subject to low sediment supply  

Microsoft Academic Search

A new data set of bimodal subaqueous channel bed sediments was analyzed for longitudinal patterns in grain size. It yielded two interesting observations: (1) separate fining trends in d50 exist for gravel and fines that overlap for ?175 river kilometers, and (2) this overlap in fining trends results in a protracted (nonabrupt) gravel to sand transition. These suggest bed patchiness

Michael Bliss Singer

2008-01-01

220

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

221

Ganges Rocks and Sand  

NASA Technical Reports Server (NTRS)

17 January 2004 The top half of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows wind-eroded remnants of sedimentary rock outcrops in Ganges Chasma, one of the troughs of the Valles Marineris system. The lower half shows a thick accumulation of dark, windblown sand. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left. These features are located near 7.6oS, 49.4oW.

2005-01-01

222

Sand Dunes in Hellas  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-537, 7 November 2003

The smooth, rounded mounds in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture are sand dunes. The scene is located in southern Hellas Planitia and was acquired in mid-southern autumn, the ideal time of year for Hellas imaging. Sunlight illuminates the scene from the upper left. These dunes are located near 49.1oS, 292.6oW. The picture covers an area 3 km (1.9 mi) wide.

2003-01-01

223

Fortune Cookie Sand Dunes  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-432, 25 July 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of small barchan sand dunes in the north polar region near 71.7oN, 51.3oW. Some of them are shaped like fortune cookies. The message these dunes provide: winds blow through this region from the lower right toward the upper left. The steep slip face slopes of these dunes, which point toward the upper left, indicate the wind direction. The scene is illuminated by sunlight from the upper right. The image is 3 km (1.9 mi) wide.

2003-01-01

224

Martian Sand Dunes  

NASA Technical Reports Server (NTRS)

6 January 2004

The north polar cap of Mars is nearly surrounded by fields of dark, windblown sand dunes. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 73.5oN, 75.0oW. The orientation of these dunes indicate that the dominant winds--particularly those that occur during storms--come from the upper left (northwest). The picture covers an area about 3 km (1.9 mi) across, and is illuminated by sunlight from the lower left.

2005-01-01

225

Model of Fluidized Bed Containing Reacting Solids and Gases  

NASA Technical Reports Server (NTRS)

A mathematical model has been developed for describing the thermofluid dynamics of a dense, chemically reacting mixture of solid particles and gases. As used here, "dense" signifies having a large volume fraction of particles, as for example in a bubbling fluidized bed. The model is intended especially for application to fluidized beds that contain mixtures of carrier gases, biomass undergoing pyrolysis, and sand. So far, the design of fluidized beds and other gas/solid industrial processing equipment has been based on empirical correlations derived from laboratory- and pilot-scale units. The present mathematical model is a product of continuing efforts to develop a computational capability for optimizing the designs of fluidized beds and related equipment on the basis of first principles. Such a capability could eliminate the need for expensive, time-consuming predesign testing.

Bellan, Josette; Lathouwers, Danny

2003-01-01

226

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

227

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

228

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

229

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

230

Stress Corrosion Cracking and Delayed Increase in Penetration Resistance after Dynamic Compaction of Sand  

E-print Network

indicating an increase in density of the sand bed. Surprisingly, cone penetration tests immediately after this phenomenon focused on possible mineral dissolution and bonding between grains. This bonding would compaction. Dissolution of minerals and pressure solution are phenomena that play an important role

Michalowski, Radoslaw L.

231

Laboratory Experiments and Hydrodynamic Modeling of a Bed Leveler Used to Level the Bottom of Ship Channels after Dredging  

E-print Network

in Haynes Coastal Engineering Laboratory ?. ??... 22 17. A picture of the Bobcat used to level the sand bed ????????? . 24 ix ix FIGURE... showed that some designs of bed levelers are friendlier to sea organisms that may inhabit trenches than other types of bed levelers. However, this thesis focused entirely on the box beam. A Bobcat (mini-bulldozer) shown in Figures 17 was used to pile...

Paul, Ephraim Udo

2011-02-22

232

Canyon sand -- S. W. Texas example of a low permeability gas reservoir  

SciTech Connect

Canyon sands are Upper Pennsylvanian deposits found in the Val Verde basin and on the Permian Basin eastern shelf, Texas, and occur in a thick clastic sequence overlying the Strawn limestone. These sandstones are considered to have been deposited during Missourian time and are formally named after the Canyon group deposited on the eastern shelf. The Canyon sand has provided commercial gas production for over 30 years. Canyon gas reservoirs, occurring at depths of 2,000--8,000 ft, have yielded almost 2 tcf of gas. The area of this producing sand covers more than 10 counties in south central Texas. The paper describes the depositional environments and lithology, diagenetic cements, reservoir, stimulation, and geologic traps. Even though the stratigraphy includes coal beds, no commercial gas has been produced from the coal beds.

Trabelsi, A. (Trabelsi (Ali), Lubbock, TX (United States))

1994-05-09

233

Red Clover  

MedlinePLUS

... et al. Phytoestrogens for vasomotor menopausal symptoms. Cochrane Database of Systematic Reviews . 2007;(4):CD001395. Nelson HD, ... 17):2057–2071. Red clover. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on ...

234

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

235

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

236

Science Learning in the Sand.  

ERIC Educational Resources Information Center

Presents activities that allow students to think about the Earth in a contextual manner and become familiar with constructive and destructive processes as they relate to sand - its origins, cyclical processes, and yielding of new products. Explores the bigger idea with a developmentally appropriate study of water, rocks, sand, physical phenomena,…

Sexton, Ursula

1997-01-01

237

Introduction Sand sole, Psettichthys melanostictus,  

E-print Network

catches (Kramer et al., 1995). Commercial landings of sand sole in California, Oregon, and Wash- ington.Pearson@noaa. gov); Samuel McNally is at 917 Columbia Street, Santa Cruz, CA 95060. ABSTRACT--Sand sole commercial fishery to make an initial determination of popu- lation status. We found that catch per unit

238

Fluidized bed heat processing  

SciTech Connect

A review of fluidized-bed processing and the general nature of heat transfer versus gas velocity in a fluidized bed includes comparisons of heating rates and descriptions of applications. Among the latter, are batch units for hardening and tempering. The fast process times possible with fluidized beds make them particularly suitable for continuous heat treating such as the processing of wire and hardening of small parts. Future directions include increasing the maximum operating temperature to 1300 degrees C. for atmosphere furnaces through the use of special non-metallic retorts for the processing high-speed tool steels and the increased usage of fluidized beds in scrap metal reclamation. 10 figures.

Fennell, A.G.

1985-08-01

239

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

240

Sand swimming lizard: sandfish  

E-print Network

We use high-speed x-ray imaging to reveal how a small (~10cm) desert dwelling lizard, the sandfish (Scincus scincus), swims within a granular medium [1]. On the surface, the lizard uses a standard diagonal gait, but once below the surface, the organism no longer uses limbs for propulsion. Instead it propagates a large amplitude single period sinusoidal traveling wave down its body and tail to propel itself at speeds up to ~1.5 body-length/sec. Motivated by these experiments we study a numerical model of the sandfish as it swims within a validated soft sphere Molecular Dynamics granular media simulation. We use this model as a tool to understand dynamics like flow fields and forces generated as the animal swims within the granular media. [1] Maladen, R.D. and Ding, Y. and Li, C. and Goldman, D.I., Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard, Science, 325, 314, 2009

Maladen, Ryan D; Kamor, Adam; Goldman, Daniel I

2009-01-01

241

Unchanging Desert Sand Dunes  

NASA Astrophysics Data System (ADS)

Deserts are one of the major landforms on earth. They occupy nearly 20% of the total land area but are relatively less studied. With the rise in human population, desert regions are being gradually occupied for settlement posing a management challenge to the concerned authorities. Unrestrained erosion is generally a feature of bare dunes. Stabilized dunes, on the other hand, do not undergo major changes in textures, and can thus facilitate the growth of vegetation. Keeping in view of the above factors, better mapping and monitoring of deserts and particularly of sand dunes is needed. Mapping dunes using field instruments is very arduous and they generate relatively sparse data. In this communication, we present a method of clustering and monitoring sand dunes through imagery captured by remote sensing sensors. Initially Radon spectrum of an area is obtained by decomposition of the image into various projections sampled at finer angular directions. Statistical features such as mode, entropy and standard deviation of Radon spectrum are used in delineation and clustering of regions with different dune orientations. These clustered boundaries are used to detect if there are any changes occurring in the dune regions. In the experiment's, remote sensing data covering various dune regions of the world are observed for possible changes in dune orientations. In all the cases, it is seen that there are no major changes in desert dune orientations. While these findings have implications for understanding of dune geomorphology and changes occurring in dune directions, they also highlight the importance of a wider study of dunes and their evolution both at regional and global scales. Results for Dataset 1 & Dataset 2 Results for Dataset 3

Gadhiraju, S.; Banerjee, B.; Buddhiraju, K.; Shah, V.

2013-12-01

242

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

243

Panel Bed Filters for Simultaneous Removal of Fly Ash and Sulfur Dioxide  

Microsoft Academic Search

Exploratory trials of three panel bed filters (using 16-30 mesh sand and operating at a face velocity around 12 ft\\/min) indicated a good probability that such a device can achieve 99% filtration efficiency on power-station fly ash. A “puff-back” technique was used to remove fly ash and a portion of the sand from the gas-entry face of a panel. Based

Arthur M. Squires; Robert Pfeffer

1970-01-01

244

Modeling a dynamically varying mixed sediment bed with erosion, deposition, bioturbation, consolidation, and armoring  

NASA Astrophysics Data System (ADS)

Erosion and deposition of bottom sediments reflect a continual, dynamic adjustment between the fluid forces applied to a sediment bed and the condition of the bed itself. Erosion of fine and mixed sediment beds depends on their composition, their vertical structure, their disturbance/recovery history, and the biota that inhabit them. This paper presents a new one-dimensional (1D), multi-layer sediment bed model for simulating erosion and deposition of fine and mixed sediments subject to consolidation, armoring, and bioturbation. The distinguishing characteristics of this model are a greatly simplified first-order relaxation treatment for consolidation, a mud erosion formulation that adapts to both Type I and II erosion behavior and is based directly on observations, a continuous deposition formulation for mud that can mimic exclusive erosion and deposition behavior, and straightforward inclusion of bioturbation effects. Very good agreement with two laboratory data sets on consolidation effects is achieved by adjusting only the first-order consolidation rate r c. Full model simulations of three idealized cases based on upper Chesapeake Bay, USA observations are presented. In the mud only case, fluid stresses match mud critical stresses at maximum erosion. A consolidation lag results in higher suspended sediment concentrations after erosional events. Erosion occurs only during accelerating currents and deposition does not occur until just before slack water. In the mixed mud and sand case without bioturbation, distinct layers of high and low sand content form and mud suspension is strongly limited by sand armoring. In the mixed mud and sand case with bioturbation, suspended mud concentrations are greater than or equal to either of the other cases. Low surface critical stresses are mixed down into the bed, constrained by the tendency to return towards equilibrium. Sand layers and the potential for armoring of the bed develop briefly, but mix rapidly. This model offers a relatively simple and robust tool for simulating the complex interactions that can affect muddy and mixed sediment bed erodibility.

Sanford, Lawrence P.

2008-10-01

245

Sex-Associated Effects on Hematologic and Serum Chemistry Analytes in Sand Rats (Psammomys obesus)  

PubMed Central

We sought to determine whether sex had a significant effect on the hematologic and serum chemistry analytes in adult sand rats (Psammomys obesus) maintained under normal laboratory conditions. According to the few data available for this species, we hypothesized that levels of hematologic and serum chemistry analytes would not differ significantly between clinically normal male and female sand rats. Data analysis revealed several significant differences in hematologic parameters between male and female sand rats but none for serum biochemistry analytes. The following hematologic parameters were greater in male than in female sand rats: RBC count, hemoglobin, hematocrit, red cell hemoglobin content, and percentage monocytes. Red cell distribution width, hemoglobin distribution width, mean platelet volume, and percentage lymphocytes were greater in female than in male sand rats. The sex of adult sand rats is a source of variation that must be considered in terms of clinical and research data. The data presented here likely will prove useful in the veterinary medical management of sand rat colonies and provide baseline hematologic and serum chemistry analyte information for researchers wishing to use this species. PMID:23294882

Kane, Julie D; Steinbach, Thomas J; Sturdivant, Rodney X; Burks, Robert E

2012-01-01

246

ANAEROBIC DEGRADATION OF COMPLEX SUBSTRATES IN FLUIDIZED BED BIOFILM REACTORS  

Microsoft Academic Search

A study of the anaerobic digestion of synthetic complex substrates, containing carbohydrates and proteins, was carried out in two lab-scale, mesophilic fluidized-bed reactors, using sand as inert support for biofilm attachment. After start-up using a soluble substrate based on glucose and acetate, particulate substrates were fed to bioreactors. One reactor was fed with a mixture of sucrose and albumin (RAS

M. Fuentes; C. Thompson; M. C. Mussati; P. A. Aguirre

247

Sea bed mechanics  

Microsoft Academic Search

This book provides a discussion on sea bed processes with engineering applications. It brings together the material currently available only in technical reports of research papers. It provides formulae and background references necessary for design calculation of problems such as sea bed or coastal erosion, and sub-marine pipeline stability. It also covers dissipation of wave energy, formation of ripples and

Sleath

1984-01-01

248

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

249

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

250

Bathing a patient in bed  

MedlinePLUS

Bed bath; Sponge bath ... Some patients cannot safely leave their beds to bathe. For these people, daily bed baths can help keep their skin healthy, control odor, and increase comfort. If moving the ...

251

Sedimentology of the Malawi Rift: Facies and stratigraphy of the Chiwondo Beds, northern Malawi  

Microsoft Academic Search

Shallow water, nearshore lake beds and fluviatile deposits exposed in the Karonga District (northern Malawi) are subdivided into several depositional units which are bounded by unconformities reflecting sedimentary breaks. Prior to the formation of a major perennial lake which also flooded the area studied, sedimentation was characterized by extensive fluviatile deposits mainly formed by reworked material of Jurassic red beds.

Christian Betzler; Uwe Ring

1995-01-01

252

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

253

Modeling bed material transport through colonial-age mill dam impoundments, northern Delaware  

NASA Astrophysics Data System (ADS)

Two hundred -year old colonial mill dam impoundments of the White Clay and Red Clay Creeks in northern Delaware are barely 20% 'filled' with sediment. Field evidence suggests that gravel-sized bed material supplied from upstream is able to pass through these impoundments, implying that the impoundment morphology has reached an equilibrium morphology controlled by the prevailing hydraulic regime. We assess this hypothesis using backwater modeling to compute local boundary shear stresses and the Wilcock-Crowe sediment transport equation to determine bed material transport rates in a representative impoundment with a ~ 2 m high dam and a 1.5 km-long impoundment. While previous conceptual models suggest that cobbles could only be transported through impoundments during catastrophic storm events or after impoundments had completely filled, our analysis demonstrates that transport rates of cobbles during the 2 year flow are significant. Even smaller discharges can be effective: the 0.5 year discharge moves coarse-grained bed material (11.2 - 32 mm) at moderate rates outside the impoundment and at low rates within the impoundment, suggesting net accumulation. Larger flows (5-25 year) transport material at similar rates both outside and within the impoundment. Averaged over time, this regime would keep the bed of the stream in quasi-equilibrium, with lower flows filling the impoundment and higher flows removing the accumulated sediment. This behavior is reminiscent of the response and recovery cycle described for quasi-equilibrium stream channels, suggesting that these impounded channels behave as graded streams with a reduced slope rather than as stagnant quasi-lacustrine systems incapable of transporting the sediment supplied from upstream. The current morphology (only 20% filled by sand and gravel) may not have existed in the past. Cores from floodplains adjacent to the impoundments reveal deposits of laminated mud suggesting a former fine-grained impoundment fill that has subsequently been eroded. Changes in land use and spillway operation have likely altered the discharge regime, sediment supply, and hydraulics of the impoundment, creating a different impoundment morphology. Our study suggests that the morphology of impoundment streams adjusts through time to achieve a quasi-equilibrium morphology controlled by the prevailing sediment supply and hydraulic regime.

Pearson, A.; Pizzuto, J. E.

2013-12-01

254

Why do gravel bed rivers meander?  

NASA Astrophysics Data System (ADS)

Gravel bed meandering channels are common on Earth and have been observed on Mars, yet little is known about the conditions required to support meandering in gravel substrates. This is problematic for stream restoration projects that often redesign channels as gravel bed meanders without a complete recipe. We supplemented previous data compilations on channel morphology with additional data from the literature to investigate the conditions that support meandering in gravel bed rivers in the field. The 127 gravel bed rivers in our database are most common along the base of the Rocky Mountains in North America, and the United Kingdom. We identified the location of 111 of the reaches and using Google Earth, subdivided those channels into 3 categories: meandering channels with occasional islands (22 rivers), sinuous channels with bars but without evidence of cutoffs (36 rivers), and meandering channels with cutoffs (33 rivers). We also separately identified channels whose median diameter was less than 10 mm (20 rivers) because their behavior differed greatly from coarser rivers. We contrasted these rivers with sinuous gravel channels (channels without bars), braided gravel channels, and sand meanders from previous literature compilations. Coarse-grained (>10 mm) meanders with cutoffs have an average Shields stress of 0.032 and range from 0.016 to 0.046. This is significantly lower than the other gravel channel types where Shields stress can exceed 0.2 for both braided and sinuous channels. We propose that gravel meanders with cutoffs are not transporting gravel downstream, but rather are reworking gravel deposited under earlier hydrologic and sediment supply regimes. We observed similar behavior during meandering experiments, where coarse sediment was not transported around bends but was exchanged between channel banks and downstream bars. The low stresses on gravel meanders with cutoffs might also be expected to correspond with low stresses on the banks, which in combination with vegetation slows bank erosion sufficiently to allow channels to maintain a meandering morphology. The relatively high Shield stresses in sinuous (non-migrating) channels were surprising, and indicate very strong banks perhaps from dense vegetation or cohesive sediment. Taken together with observations from flume experiments, we propose that gravel bed meanders require additional bank strength from vegetation or cohesive sediment, fine sediment (sand) to fill the downstream end of bars and plug chute channels and cutoffs, and low coarse sediment supply. Additional data on bank strength for the channels in the database is required to further investigate the differences between sinuous gravel channels and gravel meanders with cutoffs.

Braudrick, C. A.; Dietrich, W. E.

2011-12-01

255

Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.  

PubMed

An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210mm diameter and 1600mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850°C, 25-31.3kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ?45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field. PMID:25446789

Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

2015-02-01

256

Dispersal and memory of sand flies in an endemic area of cutaneous leishmaniasis, southern Brazil.  

PubMed

The dispersal of and the existence of memory in sand flies were measured in a transmission area of cutaneous leishmaniasis, in the municipality of Bandeirantes, Paraná, Brazil. Sand flies were caught in a rural area, with Shannon trap installed in the forest and three Falcão traps installed in a human-inhabited environment (HIE) and three others in an impacted environment presently uninhabited by humans (EUH), from 1800 to 0600 hours. The captured sand flies were marked with yellow, blue, or red fluorescent powder, according to the environments where they were captured. All marked sand flies were released at 0700 hours at a point between the three environments. The recaptures were made with 28 Falcão traps, distributed in the environments from for 10 consecutive days. The sand flies recaptured were examined under a stereomicroscope and later identified. It was concluded that sand flies are able to disperse over an average distance of 73 m, reaching 130 m in 24 h, showing that: 1) the sand flies were attracted with different intensities to each environment, and the ability to move among different environments allows the existence of enzootic cycle of Leishmania; 2) the sand flies possess a spatial memory, olfactory memory, or both, that enable them to return to the environment where they were captured initially, although the distances were different. PMID:24180102

Silva, Natália Maria Maciel Guerra; De Melo, Simone Cristina Castanho Sabaini; Massafera, Rubens; Rossi, Robson Marcelo; Silveira, Thaís Gomes Verzignassi; Teodoro, Ueslei

2013-09-01

257

Animating Sand as a Fluid Yongning Zhu  

E-print Network

Animating Sand as a Fluid by Yongning Zhu B.Sc., Peking University, 2003 A THESIS SUBMITTED;Abstract My thesis presents a physics-based simulation method for animating sand. To allow for efficiently scaling up to large volumes of sand, we abstract away the individual grains and think of the sand

Bridson, Robert

258

Continuum saltation model for sand dunes  

Microsoft Academic Search

We derive a phenomenological continuum saltation model for aeolian sand transport that can serve as an efficient tool for geomorphological applications. The coupled differential equations for the average density and velocity of sand in the saltation layer reproduce both the known equilibrium relations for the sand flux and the time evolution of the sand flux as predicted by microscopic saltation

Gerd Sauermann; Klaus Kroy; Hans J. Herrmann

2001-01-01

259

Acidic stream mitigation by limestone sand addition  

SciTech Connect

The Town Line Run watershed comprises an area of 3,600 wooded acres. The tributaries feeding the stream consist of sandstone springs that do not contribute alkalinity to the watershed, leaving the stream susceptible to acid precipitation. This has a negative affect on Iser`s Run, a native brook trout fishery above the confluence with Town Line Run. The objective in stream liming is to improve water chemistry by increasing pH, alkalinity, and reducing acidity, aluminum, and iron. Introducing crushed limestone directly into a stream from a dump truck is an inexpensive but temporary solution to accomplish this objective. In this type of liming operation, a bed of limestone is spread down the stream channel by the momentum of the stream from the introduction point, rather than manually. Water moving across this bed dissolves the limestone, increasing the pH, alkalinity, and calcium while decreasing the acidity, iron, and aluminum concentrations of the water. The size of the limestone particles is important for this purpose because particles that are too small (<150 microns) will carried away, while particles that are too large (>1000 microns) will remain at the introduction point. Our study placed 80 tons of sand-sized limestone (85% calcite) in the stream channel at a single point. Water samples were collected monthly at the following sites (1) directly upstream of the addition site, (2) 100 yards downstream of the site, and (3) 2500 yards downstream of the site. Other sample locations include (4) upstream and (5) downstream of the Town Line Run- Iser`s Run confluence and the Casselman River upstream (6) and downstream (7) of Town Line Run. The samples were analyzed for pH. Specific conductivity, Alkalinity, Acidity, Iron, Manganese, Aluminum, and Sulfate.

Brant, D.L. [WVU National Research Center for Coal and Energy, Morgantown, WV (United States); Marich, A.J. Jr. [PA Dept. of Environmental Protection, Markleton, PA (United States); Largent, K.L. [Somerset Conservation District, Somerset, PA (United States)

1996-12-31

260

Bottom bed regimes in a circulating fluidized bed boiler  

Microsoft Academic Search

This paper extends previous work on the fluidization regimes of the bottom bed of circulating flyidized bed (CFB) boilers. Pressure measurements were performed to obtain the time-average bottom bed voidage and to study the bed pressure fluctuations. The measurements were carried out in a 12 MWth CFB boiler operated at 850°C and also under ambient conditions (40°C). Two bubbling regimes

A. Svensson; F. Johnsson; B. Leckner

1996-01-01

261

Erosion of a granular bed driven by laminar fluid flow  

E-print Network

Motivated by examples of erosive incision of channels in sand, we investigate the motion of individual grains in a granular bed driven by a laminar fluid to give us new insights into the relationship between hydrodynamic stress and surface granular flow. A closed cell of rectangular cross-section is partially filled with glass beads and a constant fluid flux $Q$ flows through the cell. The refractive indices of the fluid and the glass beads are matched and the cell is illuminated with a laser sheet, allowing us to image individual beads. The bed erodes to a rest height $h_r$ which depends on $Q$. The Shields threshold criterion assumes that the non-dimensional ratio $\\theta$ of the viscous stress on the bed to the hydrostatic pressure difference across a grain is sufficient to predict the granular flux. Furthermore, the Shields criterion states that the granular flux is non-zero only for $\\theta >\\theta_c$. We find that the Shields criterion describes the observed relationship $h_r \\propto Q^{1/2}$ when the bed height is offset by approximately half a grain diameter. Introducing this offset in the estimation of $\\theta$ yields a collapse of the measured Einstein number $q^*$ to a power-law function of $\\theta - \\theta_c$ with exponent $1.75 \\pm 0.25$. The dynamics of the bed height relaxation are well described by the power law relationship between the granular flux and the bed stress.

A. E. Lobkovsky; A. V. Orpe; R. Molloy; A. Kudrolli; D. H. Rothman

2008-05-01

262

Dating of Sand Dunes Using Cosmogenic Chlorine-36: An Example From the Nebraska Sand Hills, USA  

E-print Network

Dating of Sand Dunes Using Cosmogenic Chlorine-36: An Example From the Nebraska Sand Hills, USA- ing sand dunes based on the accumulation of cosmogenic chlorine-36 in sand grains. The concen- tration of chlorine-36 in a stable sand dune primarily depends on the length of time the dune has been exposed

Zreda, Marek

263

EPA-Registered Bed Bug Products  

MedlinePLUS

EPA-Registered Bed Bug Products Resources Bed Bug Main Page Top Ten Bed Bugs Tips Joint Statement on Bed Bug Control ... Where you can use the pesticide Pesticide type Bed Bug Search Tool Enter the information as described ...

264

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

265

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

266

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

267

Infant Bedding Dangers  

MedlinePLUS

... 1993 to 2010 using data from the National Infant Sleep Position study. They found that more than half ... and loose bedding not be placed in an infant’s sleep environment. The study team says understanding trends associated ...

268

Experiment and grey relational analysis of CWS spheres combustion in a fluidized bed  

SciTech Connect

In order to study the combustion of coal water slurry (CWS) in fluidized bed boilers, artificial CWS droplet spheres were used for simulation of the spheres formed from CWS droplets which fall from the furnace top to the bed. The artificial spheres were introduced to a bench-scale fluidized bed furnace. Quartz sand was used as the bed material. The influence of the operation conditions (e.g., bed temperature, superficial gas velocity, and bed height) on the combustion characteristics was investigated. The bed temperatures were varied at 650, 750, 850, and 950{sup o}C. The gas velocities were in a range of fluidization numbers W (defined as U/U{sub mf}) of 3, 3.5, 4, and 4.5. The bed heights were varied 30, 50, 70, and 90 mm. The CWS spheres were taken out at five residence times (15, 30, 45, 60, and 75 s). The mass ratio of the residue fixed carbon to parent fixed carbon was calculated for studying the influential factors. Under the reference conditions, it is shown that the burnout time is less than 150 s. The grey relational analysis was used to study the degree of relative importance of the influential factors. The results showed that the influence of the bed height is the least, the fluidization number has the greatest influence in the early and later stages, and the bed temperature contributes most in the intermediate stages. 16 refs., 16 figs., 6 tabs.

Hui Wang; Xiumin Jiang; Jianguo Liu; Weigang Lin [Shanghai Jiao Tong University, Shanghai (China). School of Mechanical Engineering

2007-08-15

269

Sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts  

USGS Publications Warehouse

Secondarily treated domestic sewage has been disposed of on surface sand beds at the sewage treatment facility at Otis Air Force Base, Massachusetts, since 1936. Infiltration of the sewage through the sand beds into the underlying unconfined sand and gravel aquifer has resulted in a plume of sewage-contaminated ground water that is 2,500 to 3,500 feet wide, 75 feet thick, and more than 11,000 feet long. The plume extends south and southwest of the sand beds in the same direction as the regional flow of ground water, and is overlain by 20 to 50 feet of ground water derived from precipitation that recharges the aquifer. The bottom of the plume generally coincides with the contact between the permeable sand and gravel and underlying finer grained sediments. The distributions in the aquifer of specific conductance, temperature, boron, chloride, sodium, phosphorus, nitrogen (total of all species), ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. In ground water outside the plume, the detergent concentration is less than 0.1 milligrams per liter as MBAS (methylene blue active substances), the ammonia-nitrogen concentration is less than 0.1 milligrams per liter, the boron concentration is less than 50 micrograms per liter, and specific conductance is less than 80 mircromhos per centimeter. In the center of the plume, detergent concentrations as high as 2.6 milligrams per liter as MBAS, ammonia-nitrogen concentrations as high as 20 milligrams per liter, boron concentrations as high as 400 micrograms per liter, and specific conductance as high as 405 micromhos per centimeter were measured. Chloride, sodium, and boron are transported by the southward-flowing ground water without significant retardation, and seem to be diluted only by hydrodynamic dispersion. The movement of phosphorus is greatly restricted by sorption. Phosphorus concentrations do not exceed 0.05 milligrams per liter farther than 2,500 feet from the sand beds. Detergent concentrations in the plume are highest between 3,000 and 10,000 feet from the sand beds and reflect the introduction of nonbiodegradable detergents in 1946 and the conversion to biodegradable detergents in 1964. The center of the plume as far as 5,000 feet from the sand beds contains nitrogen as ammonia, but no nitrate and no dissolved oxygen. Ammonia is gradually oxidized to nitrate between 5,000 and 8,000 feet from the sand beds, and at distances greater than 8,000 feet oxidation of ammonia is essentially complete. Ammonia also is oxidized to nitrate along the top and sides of the plume within 5,000 of the beds where the contaminated ground water mixes with uncontaminated ground water that contains up to 11 milligrams per liter dissolved oxygen.

LeBlanc, Denis R.

1984-01-01

270

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

271

Mycorrhizal inoculum potentials of pure reclamation materials and revegetated tailing sands from the Canadian oil sand industry.  

PubMed

Recent improvements in the management of oil sand tailings used by the Canadian oil sand industry have resulted in the production of composite tailing sands (CT): a new challenging material for reclamation work. Jack pine (Pinus banksiana Lamb.), hybrid poplar (Populus deltoides Bartr. ex Marsh. xPopulus nigra L.) and red clover (Trifolium pratense L.) plants were used in an 8-week greenhouse bioassay to evaluate the mycorrhizal inoculum potential of CT. This inoculum potential was compared with that of three other reclamation materials [common tailing sands (TS), deep overburden (OB) and muskeg peat (MK)], and with three sites reclaimed in 1982 (R82), 1988 (R88) and 1999 (R99). CT was devoid of active mycorrhizal propagules while all other materials showed some level of inoculum potential. Arbuscular mycorrhizal fungi were observed on roots of clover or poplar grown in TS, OB, and all substrates containing peat (MK, R82, R88 and R99). Pine roots were also colonized by vesicle-forming hyphae of an unidentified fine endophyte and by dark septate fungi. Ectomycorrhizas (ECM) were observed on pine and poplar grown in OB, MK, and in soils from the two older reclaimed sites (R82 and R88). Using morpho- and molecular typing, six ECM fungi were identified to the genus or species level: Laccaria sp., Thelephora americana, Wilcoxina sp. (E-strain), Tuber sp. (I-type), a Sebacinoid, and a Pezizales species. Laccaria sp. and Wilcoxina sp. were the most frequently observed ECM species. PMID:15883852

Bois, G; Piché, Y; Fung, M Y P; Khasa, D P

2005-05-01

272

Sand transport in the lower Mississippi River does not yield to dams: Applications for building deltaic land in Louisiana  

NASA Astrophysics Data System (ADS)

The Mississippi Delta is presently undergoing a catastrophic drowning, whereby 5000 km2 of low-lying wetlands have converted to open water. This land loss is primarily the result of: a) relative sea-level rise, occurring due to the combined effect of rapid subsidence associated with subsurface fluids extraction and eustatic rise; b) leveeing and damming of the river and its tributaries, which restricts sediment delivery to and dispersal within the delta; and c) severe excavation of the delta for navigation channels. It has been argued that continued net land loss of the Mississippi Delta is inevitable due to declining measured total (sand and mud) suspended sediment loads over the past 6 decades. However, recent research has documented that the key to delta growth is deposition of sand, which accounts for ~50-70% of modern and ancient (up to 9 m.a.) Mississippi Delta deposits, but comprises only ~20% of the sampled portion of the total load. Here we present new analysis of existing data to show that sand transport has not diminished since dam construction. Furthermore, we produce a numerical model based on the mass balance of bed material loads over the lower 1600 km of the Mississippi River to show that mining of sand from the channel bed continues to replenish downstream sand loads. For example, our model results indicate that it requires approximately 240 years for a reduced sand load to reach the delta apex. Furthermore, our calculations indicate that sand load at the delta apex is reduced by a noticeable amount (17%) only after about 600 years. We also show how channel bed elevations are predicted to change over the lower 1600 km of the river channel due to channel mining. Channel-bed degradation is greatest at the upstream end of the study reach and decreases downstream. After 300 years the wave of significant degradation has just passed ~800 km downstream, or roughly half of our model domain. These results are in contrast to the measurements which concern the reduction of total suspended sediment load, and here we provide a reasonable hypothesis to help explain: sand possesses a much slower time scale of movement through a sand-bed river compared to mud, because sand exchanges with the bed, building dunes and bars that migrate gradually downstream, whereas the mud travels the length of the system in suspension as washload. This produces orders-of-magnitude difference in transport timescales between mud -- which accounts for ~80% of the total suspended sediment load of the Mississippi River -- and sand (bedload and suspended load). Combined with the abundance and availability of sand to be mined within the main channel, the river effectively buffers the reduction of sand load arising due to main-channel dams. Thus the bed of the lower Mississippi River downstream will provide a stable supply of sand to the delta for the foreseeable future.

Nittrouer, J. A.; Viparelli, E.

2013-12-01

273

Annual Logging Symposium, June 3-6, 2007 QUANTITATIVE STUDIES OF RELATIVE DIP ANGLE AND BED -  

E-print Network

the sedimentary structure of rock formations penetrated by the well. However, the effect of sedimentary structure. Mendoza, and C. Torres-Verdín, The University of Texas at Austin; W.E. Preeg, Consultant, E. Stockhausen/HZ wells penetrating thinly-bedded formations comprised of alternating sands and shales. Typically

Torres-Verdín, Carlos

274

A Geography-Aware Scalable Community Wireless Network Test Bed Bow-Nan Cheng, Shivkumar Kalyanaraman  

E-print Network

(eg: power, telephone lines, ISM wireless bands) and focus on scalability and co test bed lab where RF effects of distances of thou- sands of meters can be simulated with server, antenna, and variable attenuator clusters.1 1. Introduction The "last-mile" broadband infrastructure

Kalyanaraman, Shivkumar

275

Morphodynamically-based sediment budget in gravel-bed rivers: methodological problems (Invited)  

NASA Astrophysics Data System (ADS)

Estimation of the bed-material sediment budget from morphological changes has been adopted as an acceptable practice for gravel-bed rivers in which trends of morphological change persist for some considerable period. The qualification is important: co-located erosion and deposition within a survey interval biases the result. Another source of significant bias that has not generally been noted is the ';two-speed' nature of the fluvial sediment system by which sand moves through a reach much more quickly than gravel. Resident sand occurs in particular sedimentary environments (e.g., bar tail) and as cover sands - sometimes extensively so - in addition to forming gravel matrix. These materials are readily entrained during high flows and may constitute a large proportion of mobile sediment during flood. Unless explicitly accounted for in end-point assessments, they may significantly bias the gravel budget. Furthermore, they may easily be replaced during a single flood event, introducing the problem of co-located exchange. In Fraser River, British Columbia, a large gravel-bed river that appears suitable for sediment budget calculations by morphodynamic methods, an attempt is being made to understand this problem by mapping surficial sand using hyperspatial air photography and assessing its volume by application of a distribution of sand depths. The volume of these deposits may thereby be separately estimated and discounted in the assessments of changing gravel storage.

Church, M. A.

2013-12-01

276

Volatiles combustion in fluidized beds. Final technical report, 4 September 1992--4 June 1995  

SciTech Connect

The goal of this project is to investigate the conditions in which volatiles will burn within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization are being conducted to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. A review of the work conducted under this grant is presented in this Final Technical Report. Both experimental and theoretical work have been conducted to examine the inhibition of the combustion by the fluidized bed material, sand. It has been shown that particulate phase at incipient fluidization inhibits the combustion of propane by free radical destruction at the surface of sand particles within the particulate phase. The implications of these findings is that at bed temperatures lower than the critical temperatures, gas combustion can only occur in the bubble phase or at the top surface of a bubbling fluidized bed. In modeling fluidized bed combustion this inhibition by the particulate phase should be included.

Pendergrass, R.A. II; Raffensperger, C.; Hesketh, R.P.

1996-02-29

277

A comparative study of sand and natural zeolite as filtering media in tertiary treatment of wastewaters from tourist areas  

Microsoft Academic Search

Anaerobic effluents from a fixed bed reactor treating sewage water from tourist areas were treated by two high rate filters at laboratory scale one packed with sand and the other with natural zeolite with the aim of obtaining final effluents with quality for irrigation of land or disposal in tourist zones. The ranges of particle sizes for the two filtering

O. Reyes; E. Sánchez; A. Pellón; R. Borja; M. F. Colmenarejo; Z. Milán; M. Cruz

1997-01-01

278

A comparative study of sand and natural zeolite as filtering media in tertiary treatment of wastewaters from tourist areas  

Microsoft Academic Search

Anaerobic effluents from a fixed bed reactor (FBR) treating sewage water from tourist areas were treated by two high rate filters at laboratory scale one packed with sand and the other with natural zeolite with the aim of obtaining final effluents with quality for irrigation of land or disposal in tourist zones. During the experiments analysis of turbidity, COD, BOD,

O. Reyes; E. Sanchez; A. Pellon; R. Borja; M. F. Colmenarejo; Z. Milan; M. Cruz

1997-01-01

279

Paleocene-eocene lignite beds of southwest Alabama: Parasequence beds in highstand systems tracts  

SciTech Connect

In southwest Alabama, lignite beds are present in at least four stratigraphic intervals that span approximately 8 m.y. of geologic time. Lignite is found in the Paleocene Oak Hill Member and Coal Bluff Member of the Naheola Formation of the Midway Group and the Paleocene Tuscahoma Sand and the Eocene Hatchetigbee Formation of the Wilcox Group. Lignite beds range in thickness from 0.5 to 11 ft and consist of 32-53% moisture, 13-39% volatile matter, 4-36% fixed carbon, and 5-51% ash. These Paleocene and Eocene lignite beds occur as parasequence deposits in highstand systems tracts of four distinct third-order depositional sequences. The lignite beds are interpreted as strata within highstand systems tract parasequences that occur in mud-dominated regressive intervals. Lignite beds were deposited in coastal marsh and low-lying swamp environments as part of deltaic systems that prograded into southwestern Alabama from the west. As sediment was progressively delivered into the basin from these deltas, the effects of relative sea level rise during an individual cycle were overwhelmed, producing a net loss of accommodation and concomitant overall basinward progradation of the shoreline (regression). Small-scale fluctuations in water depth resulting from the interaction of eustasy, sediment yield, and subsidence led to cyclical flooding of the low-lying coastal marshes and swamps followed by periods of progradational and regression. Highstand systems tract deposition within a particular depositional sequence culminated with a relative sea level fall that resulted in a lowering of base level and an abrupt basinward shift in coastal onlap. Following sea level fall and the subsequent accumulation of the lowstand deposits, significant relative sea level rise resulted in the marine inundation of the area previously occupied by coastal marshes and swamps and deposition of the transgressive systems tract of the overlying sequence.

Mancini, E.A.; Tew, B.H. (Univ. of Alabama, Tuscaloosa, AL (United States)); Carroll, R.E. (Geologic Survey of Alabama, Tuscaloosa, AL (United States))

1993-09-01

280

Reversal in Migration of Gravel-Sand Transition  

NASA Astrophysics Data System (ADS)

Downstream lithofacies change is an important key to interpret fluviodeltaic depositional environment, which can be recognized by lithologic features, such as grain-size. It has been generally accepted that changes in the downstream position of grain-size transition (e.g., gravel-sand transition) are attributed to variations in basinal forcing (e.g., climate variation, sea-level change and basin subsidence), factors that also cause shoreline migration. However, no quantitative model for predicting evolution of fluviodeltaic strata thoroughly incorporates lithofacies boundaries and allows their free individual migrations. In this presentation, I present a delta evolution model to provide the quantitative understanding of the relationship between the external moving boundary (delta shoreline) and the internal moving boundaries (grain-size transitions). By treating internal coarse to fine grain-size transitions as moving boundaries, the model is capable of accurately predicting the dynamic interactions between the upstream river reaches with different dominant grain-sizes and the downstream shoreline migration in response to base-level changes. For simplicity, the model employs one grain-size transition between the upstream gravel-bed reach and the downstream sand-bed reach and constant rates of water discharge, sediment supply, and relative sea-level rise. Test runs with ranges of sediment supply rates and relative sea-level rise rates show cases for retreat of the gravel-sand transition while the shoreline is still prograding, and thus reveal the condition for reversal in migration of the internal grain-size boundary against the direction of a growing fluviodeltaic system. The model can be used to provide baseline conditions for uniform migration direction of both internal lithofacies transitions and shoreline in fluviodeltaic systems that can be used to accurately assess the trajectory of grain-size transition in sedimentary strata as a proxy for environmental change.

Kim, W.

2011-12-01

281

Bed composition generation for morphodynamic modeling: Case study of San Pablo Bay in California, USA  

USGS Publications Warehouse

Applications of process-based morphodynamic models are often constrained by limited availability of data on bed composition, which may have a considerable impact on the modeled morphodynamic development. One may even distinguish a period of "morphodynamic spin-up" in which the model generates the bed level according to some ill-defined initial bed composition rather than describing the realistic behavior of the system. The present paper proposes a methodology to generate bed composition of multiple sand and/or mud fractions that can act as the initial condition for the process-based numerical model Delft3D. The bed composition generation (BCG) run does not include bed level changes, but does permit the redistribution of multiple sediment fractions over the modeled domain. The model applies the concept of an active layer that may differ in sediment composition above an underlayer with fixed composition. In the case of a BCG run, the bed level is kept constant, whereas the bed composition can change. The approach is applied to San Pablo Bay in California, USA. Model results show that the BCG run reallocates sand and mud fractions over the model domain. Initially, a major sediment reallocation takes place, but development rates decrease in the longer term. Runs that take the outcome of a BCG run as a starting point lead to more gradual morphodynamic development. Sensitivity analysis shows the impact of variations in the morphological factor, the active layer thickness, and wind waves. An important but difficult to characterize criterion for a successful application of a BCG run is that it should not lead to a bed composition that fixes the bed so that it dominates the "natural" morphodynamic development of the system. Future research will focus on a decadal morphodynamic hindcast and comparison with measured bathymetries in San Pablo Bay so that the proposed methodology can be tested and optimized. ?? 2010 The Author(s).

van der Wegen, M.; Dastgheib, A.; Jaffe, B.E.; Roelvink, D.

2011-01-01

282

Fluidized bed pyrolysis of bitumen-impregnated sandstone at sub-atmospheric conditions  

SciTech Connect

A 15.2 cm diameter fluidized bed reactor was designed, built, and operated to study the pyrolysis of oil sands at pressures slightly less than atmospheric. Fluidizing gas flow through the reactor was caused by reducing the pressure above the bed with a gas pump operating in the vacuum mode. Pyrolysis energy was supplied by a propane burner, and the hot propane combustion gases were used for fluidization. The fluidized bed pyrolysis at reduced pressure using combustion gases allowed the reactor to be operated at significantly lower temperatures than previously reported. At 450[degree], over 80% of the bitumen fed was recovered as a liquid product, and the spent sand contained less than 1% coke. The liquid product recovery system, by design, yielded three liquid streams with distinctly different properties.

Fletcher, J.V.; Deo, M.D.; Hanson, F.V.

1993-01-01

283

Fluidized bed pyrolysis of bitumen-impregnated sandstone at sub-atmospheric conditions  

SciTech Connect

A 15.2 cm diameter fluidized bed reactor was designed, built, and operated to study the pyrolysis of oil sands at pressures slightly less than atmospheric. Fluidizing gas flow through the reactor was caused by reducing the pressure above the bed with a gas pump operating in the vacuum mode. Pyrolysis energy was supplied by a propane burner, and the hot propane combustion gases were used for fluidization. The fluidized bed pyrolysis at reduced pressure using combustion gases allowed the reactor to be operated at significantly lower temperatures than previously reported. At 450{degree}, over 80% of the bitumen fed was recovered as a liquid product, and the spent sand contained less than 1% coke. The liquid product recovery system, by design, yielded three liquid streams with distinctly different properties.

Fletcher, J.V.; Deo, M.D.; Hanson, F.V.

1993-03-01

284

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

285

Toxicity of nickel to the earthworm and the applicability of the neutral red retention assay  

E-print Network

Toxicity of nickel to the earthworm and the applicability of the neutral red retention assay JANECK of exposure to a nickel-chloride spiked loamy sand soil. The ability of a simple earthworm biomarker-red retention time showed large individual variation for the earthworms within each exposure concentration

Hopkin, Steve

286

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.

287

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

288

Stochastic analysis of particle movement over a dune bed  

USGS Publications Warehouse

Stochastic models are available that can be used to predict the transport and dispersion of bed-material sediment particles in an alluvial channel. These models are based on the proposition that the movement of a single bed-material sediment particle consists of a series of steps of random length separated by rest periods of random duration and, therefore, application of the models requires a knowledge of the probability distributions of the step lengths, the rest periods, the elevation of particle deposition, and the elevation of particle erosion. The procedure was tested by determining distributions from bed profiles formed in a large laboratory flume with a coarse sand as the bed material. The elevation of particle deposition and the elevation of particle erosion can be considered to be identically distributed, and their distribution can be described by either a ' truncated Gaussian ' or a ' triangular ' density function. The conditional probability distribution of the rest period given the elevation of particle deposition closely followed the two-parameter gamma distribution. The conditional probability distribution of the step length given the elevation of particle erosion and the elevation of particle deposition also closely followed the two-parameter gamma density function. For a given flow, the scale and shape parameters describing the gamma probability distributions can be expressed as functions of bed-elevation. (Woodard-USGS)

Lee, Baum K.; Jobson, Harvey E.

1977-01-01

289

Tenth annual fluidized bed conference  

SciTech Connect

The proceedings of the Tenth Annual Fluidized Bed Conference is presented. The Conference was held November 14-15, 1994 in Jacksonville, FL and covered such topics as: opportunity fuels, the fluid bed market, bubbling fluid bed retrofitting, waste fuel-based circulating fluidized-bed project, construction permits for major air pollution sources, fluidized bed residues, uses for fluidized bed combustion ash, ash pelletization, sorbents for FBC applications, refractory maintenance, and petroleum coke. A separate abstract and indexing have been prepared for each paper for inclusion in the Energy Science and Technology Database.

NONE

1994-12-31

290

Fluidized-bed combustion apparatus  

SciTech Connect

A fluidized bed shell boiler for producing steam or hot water or a fluidized bed hot gas generator or incinerator in which the position at which bed material is deposited downstream of the bed is controlled. A baffle of firebrick with gas-flow passages extending through the baffle is positioned in the tube downstream of the bed. Gas velocities are distributed across the tube so that bed material is preferentially deposited in the combustion chamber downstream of the furnace tube. Deposition in the furnace tube is reduced to zero or to a negligible amount and deposition downstream of the combustion chamber is reduced.

Brealey, L.; Demircan, N.; Wilson, J.H.

1984-03-06

291

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

292

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

293

7 CFR 2902.15 - Bedding, bed linens, and towels.  

Code of Federal Regulations, 2010 CFR

...the finished product. The 12 percent biobased content must be of a qualifying biobased feedstock. Cotton, wool, linen, and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of bedding, bed linens, and...

2010-01-01

294

7 CFR 3201.15 - Bedding, bed linens, and towels.  

Code of Federal Regulations, 2013 CFR

...the finished product. The 12 percent biobased content must be of a qualifying biobased feedstock. Cotton, wool, linen, and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of bedding, bed linens, and...

2013-01-01

295

7 CFR 3201.15 - Bedding, bed linens, and towels.  

Code of Federal Regulations, 2012 CFR

...the finished product. The 12 percent biobased content must be of a qualifying biobased feedstock. Cotton, wool, linen, and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of bedding, bed linens, and...

2012-01-01

296

7 CFR 3201.15 - Bedding, bed linens, and towels.  

...the finished product. The 12 percent biobased content must be of a qualifying biobased feedstock. Cotton, wool, linen, and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of bedding, bed linens, and...

2014-01-01

297

7 CFR 2902.15 - Bedding, bed linens, and towels.  

Code of Federal Regulations, 2011 CFR

...the finished product. The 12 percent biobased content must be of a qualifying biobased feedstock. Cotton, wool, linen, and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of bedding, bed linens, and...

2011-01-01

298

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

299

Fluidized bed coal desulfurization  

NASA Technical Reports Server (NTRS)

Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

Ravindram, M.

1983-01-01

300

Intramural Sports Sand Volleyball League  

E-print Network

Handbook. Insurance The Department of Recreational Sports does not provide health or accident insuranceIntramural Sports Sand Volleyball League Summer 2014 Intramural Sports Calendar of Events Summer 2014 Potential Division Offerings Men's (Tuesdays) Women's (Tuesdays) Co-Rec (Wednesdays) Sports

Escher, Christine

301

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

302

Red Files  

NSDL National Science Digital Library

Red Files, a four-part documentary series from PBS, utilizes previously unavailable archival sources and interviews to present a fascinating look at the Soviet Union and its Cold War rivalry with the US. This attractive companion site offers a number of resources related to each of the four episodes: Secret Victories of the KGB, Soviet Sports Wars, Secret Soviet Moon Mission, and Soviet Propaganda. For each installment, users will find a story synopsis, the Producer's script, theme music, updates on related events, human interest stories, complete interview transcripts, video clips, a reference section, access to related sections of Russian Archives Online, maps, a timeline, lesson plans, and more. Additional offerings include a collection of links mentioned in the series and an internal search engine. This site joins an already strong tradition at PBS of creating sites that are actual companions to the program, offering new and expanded content for interested users.

303

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

2014-08-27

304

Holocene wave conditions and wave-induced sand transport in the southern North Sea  

NASA Astrophysics Data System (ADS)

Results are presented of a simple point model of wind-wave conditions (calculated using the JONSWAP wave-growth formulations), wave-induced bottom orbital velocities (linear Airy and Stokes theory) and wave-induced sand-transport magnitudes and directions (Bailard bed-load transport formulation) in the southern North Sea. The main aims of the study are to establish the contribution of wind waves to the instantaneous, and large-scale, open-marine, long-term sand transport, and to determine the dominant transport directions and relative magnitudes. A sensitivity study for the wind climate was carried out, showing a linear response of the net sand transport to the directional distribution of the wind climate, except in a zone of about 100 km width along the coasts where the transport pattern is insensitive to such changes. The model is not only applied to the present-day conditions, but also to palaeo situations throughout the Holocene. The palaeo simulations are carried out to demonstrate that the wind-wave conditions and associated orbital velocities and sand-transport patterns have changed over time as the basin geometry changed due to the spatially variable relative sea-level rise. The near-bottom orbital velocities are sufficient to initiate sand motion for large parts of the southern North Sea during storm conditions, now and in the past. The sand is transported in this model by the wave asymmetry, the Stokes-drift induced return current and boundary-layer streaming, but the sand stirred up by waves is in reality also available for advection by tidal and residual currents. The present-day wind climate was assumed for the palaeo-calculations. The results show that the mean wave heights increased since 7.5 kyr BP, the largest changes occurring in the most shallow water, while the mean wave periods remained the same. The wave-induced sand transport mode changed from dominantly suspended transport before 6 kyr BP to dominantly bed-load transport thereafter due to the increasing water depth. The overall direction of the bed-load transport between 6 kyr BP and the present was from east to west, the magnitude decreased slightly. The transports resulted in an erosion zone along the Dutch and Belgian coast, and deposition in the Southern Bight. The interpretation of these results is discussed in the context of other transport factors (tides, wind-driven flow).

van der Molen, J.; de Swart, H. E.

2001-10-01

305

Breakout SessionIII,Bed-Materialand Bed-TopographyMeasurement  

E-print Network

Breakout SessionIII,Bed-Materialand Bed-TopographyMeasurement: DataNeeds,Uncertainty by each of the represented agencies and uncertainties associated with these data were also discussed measurement methods used in bathymetric surveys of underwater bed topography. These sources of error include

306

Incremental subglacial meltwater sediment deposition and deformation associated with repeated ice-bed decoupling: a case study from the Island of Funen, Denmark  

NASA Astrophysics Data System (ADS)

On the Island of Funen, Denmark, sediments that are 4-7 m below the land surface consist of a 2-4 m thick sequence of stacked and folded glaciofluvial sediments overlain by a 2-3 m thick basal till. The glaciofluvial sediments consist of tabular beds of planar-stratified, massive and cross-stratified sand and gravel with localized channel fills of open-framework gravel. Sand and gravel beds exhibit curvilinear sheath folding often leading to eye folds. This folding is attributed to repeated glacier-bed decoupling and recoupling, with subglacial deposition of sand and gravel by meltwater occurring during the decoupling phase and deformation occurring during recoupling. Sand and gravel beds are typically separated by silty clay beds and laminations recording slackwater deposition within subglacial cavities. Folds frequently display attenuated upper limbs reflecting shearing associated with overlying ice movement. On lower fold limbs, only localized thrusting is observed, suggesting water saturation of sands and gravels during deformation, and relatively low strain rates. Folds are frequently truncated by overlying sand and gravel beds. No evidence of shearing is found along these contacts which are interpreted as erosional surfaces. Thus, we propose that the glaciofluvial sediment sequence records incremental, step-wise subglacial deposition and deformation rather than wholesale deformation following emplacement of the entire glaciofluvial sequence. Specifically, we envisage that individual beds were deposited and folded subglacially, with ice-bed decoupling occurring during sediment deposition followed by recoupling and shearing of the upper bed surface by the ice base to produce folds with attenuated upper limbs. Incremental deformation and folding were facilitated by elevated porewater pressure within the sediments. Silty clay beds helped to maintain elevated porewater pressure by acting as local aquitards. A general absence of till from the glaciofluvial sequence (save for localized cm-scale blocks) suggests either non-deposition or reworking into the glaciofluvial sediments. Deposition of tabular sand and gravel beds and open-framework gravel filling scours within single beds suggest broad sheet-like subglacial flows (10-100 m wide) that become increasingly channelized. We propose that the sedimentary sequence records a highly dynamic glaciohydraulic system characterized by repeated localized subglacial cavity development, and storage and release of meltwater leading to glacier decoupling that may have facilitated fast flow of the Baltic Ice Stream.

Lesemann, Jerome-Etienne; Alsop, G. Ian; Piotrowski, Jan A.

2010-11-01

307

Development of stresses in cohesionless poured sand  

E-print Network

Development of stresses in cohesionless poured sand By M. E. Cates1 , J. P. Wittmer1 , J a conical sandpile, created by pouring sand from a point source onto a rough rigid support, shows) is required for systems with two-dimensional symmetry, such as a wedge of sand; for a three

Claudin, Philippe

308

EFFECTS of OIL MIXED with CARBONIZED SAND  

E-print Network

m #12;#12;EFFECTS of OIL MIXED with CARBONIZED SAND on AQUATIC ANIMALS Marine Biological l SAND ON AOTTATIC ANIMALS By Walter A. Chipman and Paul S. Gaits off. Fishery Research Biologists CONTENT Pago Preface Introduction 1 Injury to aquatic life caused by oil. 2 Amount of carbonized sand

309

Animating Sand as a Fluid Yongning Zhu  

E-print Network

Animating Sand as a Fluid Yongning Zhu University of British Columbia Robert Bridson University of British Columbia Figure 1: The Stanford bunny is simulated as water and as sand. Abstract We present a physics-based simulation method for animating sand. To allow for efficiently scaling up to large volumes

Teschner, Matthias

310

Fluvial sand shapes: effects of tributary mixing  

Microsoft Academic Search

Similarities and differences in gross shapes of fluvial quartz sand grains contain information useful for interpretation of sediment transport history. The shapes of sand grains in a given river depend on the source, or sources, of sand within the drainage basin and on the abrasion and shape sorting that has occurred during transport. It is highly unlikely that 2 major

1985-01-01

311

Treating tar sands formations with karsted zones  

DOEpatents

Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

Vinegar, Harold J. (Bellaire, TX); Karanikas, John Michael (Houston, TX)

2010-03-09

312

Sand Dome on a Steam Engine  

USGS Multimedia Gallery

Steam engines used high-grade silica sand for traction on the rails. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially...

313

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 ,C O 2, CO and NO concentration profiles in the conical FBC operated at 82.5-82.8 kg\\/h fuel feed rate and various values of excess air (of about 40, 60,

V. I. Kuprianova; W. Permchartb K. Janvijitsakula

314

JAMA Patient Page: Bed Bugs  

MedlinePLUS

... of the American Medical Association JAMA PATIENT PAGE Bed Bugs B ed bugs, Cimex lectularius , have been ... which thrives in temperate and tropical regions worldwide. Bed bugs are exclusively hematophagous (they feed only on ...

315

Pliocene Lignite Bed  

USGS Multimedia Gallery

Seam or bed of Pliocene lignite from a mine in the Balkan endemic nephropathy (BEN) area of Romania. Rainwater falling onto the surface penetrates into the ground, becoming ground water, and leaches toxic organic substances from this coal. The ground water continues to BEN villages in the valleys be...

2009-09-10

316

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...

317

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

NASA Astrophysics Data System (ADS)

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.

1999-09-01

318

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

319

Topology of compressed pebble beds  

Microsoft Academic Search

Thermal stresses occurring during operation of helium-cooled pebble bed blankets will cause pebble deformations which increase the pebble bed thermal conductivity due to an increase of contact surfaces between the pebbles. The dependence of the thermal conductivity from pebble bed strain is generally determined in test set-ups where only global quantities (uniaxial stress, strain and temperature) are measured. For the

J. Reimann; R. A. Pieritz; R. Rolli

2006-01-01

320

A thick Tethyan multi-bed tsunami deposit preserving a dinosaur megatracksite within a coastal lagoon (Barremian, eastern Spain)  

NASA Astrophysics Data System (ADS)

A Thick multiple-bed tsunami deposit consisting of sandstones and conglomerates has been discovered and investigated in the Camarillas Formation (~ 130.6-128.4 Ma, Barremian age) in eastern Spain. The tsunami deposit is interbedded within red mudstones deposited in mud flats of a back-barrier system. It crops out along 7 km in length and at its base a great number of dinosaur tracks assigned to sauropods, ornithopods and theropods have been preserved as natural casts; then constituting an exceptional regional megatracksite associated with tsunami deposits. On the basis of sedimentological features and the lateral and vertical architecture of the involved lithofacies, up to five couplets of inflow-backflow deposits, formed by a tsunami wave train, have been recognized overlying the tracks. Although sedimentation mainly took place during backflow currents, inflows led to the removal of sand from a fronting barrier island and the rip-up of lagoonal carbonate and clay pebbles, depositing them in the protected back-barrier lagoon. Its unusually great thickness is interpreted, among others, as being the result of the filling of the previous low topography of the back-barrier lagoon.

Navarrete, Rocío; Liesa, Carlos L.; Castanera, Diego; Soria, Ana R.; Rodríguez-López, Juan P.; Canudo, José I.

2014-11-01

321

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

322

Sediment Transport and Bed Material Grain Size Distributions along the Upper Colorado River, Rocky Mountain National Park, CO  

NASA Astrophysics Data System (ADS)

The Upper Colorado River in Rocky Mountain National Park is dynamically adjusting to approximately 35,000 m3 of sediment introduced by a debris flow in May 2003. Bed material and sediment transport measurements since 2003 indicate that the debris flow source material is the dominant control on grain size distributions of bed material and bedload in transport. Hydrothermally altered Tertiary welded rhyolite tuff within moraines on hillslopes comprised the bulk of debris flow material initially and this material has since been remobilized and sorted by fluvial processes, forming extensive alluvium along the Colorado River. Oxidation of the ~5% pyrite in the tuff causes volume changes and in-situ disintegration of the alluvium, creating abundant sand- and gravel-sized material. At temporary gaging stations installed downstream from the main debris flow fan, measured water discharge spans a threefold range and bedload a six order-of-magnitude range in transport rate. Maximum bedload transport exceeds 1000 g/s at the highest measured discharge (3.5 m3/s) when the proportion of sand was >80%. Fractional bedload transport is related to proximity to the fan source, bed slope, and discharge, with 4-16 mm gravel mobilized closer to the source at higher bed slopes and discharges. The high sand content within transported bedload is in contrast to bed material grain size distributions which, during low flow, contain less than 15% sand and a D50 that has varied from fine to very coarse gravel. The bed D50 declined by two size classes at gaging stations in 2011 due to extensive aggradation as a result of the highest discharge in 60 years of record. Understanding the river's response to the sand and gravel input, as well as the fate of the hydrothermally altered material, will facilitate decisions on the appropriate mixed-size sediment transport model to predict size sorting and transient channel adjustments to plan for restoration along the Upper Colorado River.

Rathburn, S. L.; Grimsley, K. J.; Rubin, Z.

2011-12-01

323

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

324

Fluidized-bed combustion  

SciTech Connect

This report describes the activities of the Morgantown Energy Technology Center's research and development program in fluidized-bed combustion from October 1, 1987, to September 30, 1989. The Department of Energy program involves atmospheric and pressurized systems. Demonstrations of industrial-scale atmospheric systems are being completed, and smaller boilers are being explored. These systems include vortex, multi-solid, spouted, dual-sided, air-cooled, pulsed, and waste-fired fluidized-beds. Combustion of low-rank coal, components, and erosion are being studied. In pressurized combustion, first-generation, combined-cycle power plants are being tested, and second-generation, advanced-cycle systems are being designed and cost evaluated. Research in coal devolatilization, metal wastage, tube corrosion, and fluidization also supports this area. 52 refs., 24 figs., 3 tabs.

Botros, P E

1990-04-01

325

Sand Sheet on Crater Floor  

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.

As with yesterday's image, this dune field is located inside a crater, in this case an unnamed crater at 26 degrees North latitude. In this VIS image the dunes are coalescing into a sand sheet, note the lack of dune forms to the north of the small hills. The presence of ridges and hills in the area is affecting the dune shapes.

Image information: VIS instrument. Latitude 26.4, Longitude 62.7 East (297.3 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

326

Combustion in fluidized beds  

Microsoft Academic Search

Circulating fluidized-bed (CFB) combustion systems have become popular since the late 1970s, and, given the current level of activity in the area,it is clear that this technology has a stable future in the boiler market. For standard coal combustion applications, competition is fierce with mature pulverized-fuel-based (PF) technology set to maintain a strong profile. CFB systems, however, can be more

F. J. Dry; R. D. La Nauze

1990-01-01

327

Bed expansion crucible tests  

Microsoft Academic Search

The Am\\/Cm program will vitrify the americium and curium currently stored in F-canyon. A batch flowsheet has been developed (with non-radioactive surrogate feed in place of the F-canyon solution) and tested full-scale in the 5-inch Cylindrical Induction Melter (CIM) facility at TNX. During a normal process run, a small bed expansion occurs when oxygen released from reduction of cerium (IV)

2000-01-01

328

Circulating Fluid Bed Combustor  

E-print Network

presents the conceptual design air, feed coal and limestone, and of a circulating fluidized bed coal recirculating solids are mixed. The feed combustor to be used as a steam generator solids constitute less than 1% of the for a power plant. The design... variables recirculating solids. The recirculating are selected to optimize the combustor's sol ids, at 1650? F, heat the air and feed performance, size and cost. Some solids to the operating temperature in a advantages of the combustor include good...

Fraley, L. D.; Do, L. N.; Hsiao, K. H.

1982-01-01

329

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

330

Reevaluation of Stevens sand potential - Maricopa depocenter, southern San Joaquin basin, California  

SciTech Connect

During the upper Miocene in the Southern San Joaquin basin surrounding highlands contributed coarse material to a deep marine basin dominated by fine grained silicious bioclastic deposition. these coarse deposits became reservoirs isolated within the silicious Antelope Shale Member of the Monterey Formation. In the southern Maricopa depocenter these Stevens sands are productive at Yowlumne, Landslide, Aqueduct, Rio Viejo, San Emidio Nose, Paloma, and Midway-Sunset fields, and are major exploration targets in surrounding areas. In the ARCO Fee lands area of the southern Maricopa depocenter, Stevens sands occur as rapidly thickening lens-shaped bodies that formed as channel, levee, and lobe deposits of deep-marine fan systems. These fans were fed from a southerly source, with apparent transport in a north-northwesterly direction. Sands deflect gently around present-day structural highs indicating that growth of structures influenced depositional patterns. Correlations reveal two major fan depositional intervals bounded by regional N, O, and P chert markers. Each interval contains numerous individual fan deposits, with many lobes and channels recognizable on three-dimensional seismic data. In addition to these basinal sand plays presently being evaluated, ARCO is pursuing a relatively new trend on Fee lands along the southern basin margin, where correlation to mountain data reveals Stevens sands trend into the steeply dipping beds of the mountain front. This area, the upturned Stevens,' has large reserve potential and producing analogies at Metson, Leutholtz, Los Lobos, and Pleito Ranch fields.

Kolb, M.M.; Parks, S.L. (ARCO Oil and Gas Co., Bakersfield, CA (United States))

1991-02-01

331

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

332

Combustion in fluidized beds  

SciTech Connect

Circulating fluidized-bed (CFB) combustion systems have become popular since the late 1970s, and, given the current level of activity in the area,it is clear that this technology has a stable future in the boiler market. For standard coal combustion applications, competition is fierce with mature pulverized-fuel-based (PF) technology set to maintain a strong profile. CFB systems, however, can be more cost effective than PF systems when emission control is considered, and, as CFB technology matures, it is expected that an ever-increasing proportion of boiler installations will utilize the CFB concept. CFB systems have advantages in the combustion of low-grade fuels such as coal waste and biomass. In competition with conventional bubbling beds, the CFB boiler often demonstrates superior carbon burn-out efficiency. The key to this combustion technique is the hydrodynamic behavior of the fluidized bed. This article begins with a description of the fundamental fluid dynamic behavior of the CFB system. This is followed by an examination of the combustion process in such an environment and a discussion of the current status of the major CFB technologies.

Dry, F.J.; La Nauze, R.D. (CSIRO, Div. of Mineral and Process Engineering, Clayton, Victoria 3168 (AU))

1990-07-01

333

Modeling of flood-deposited sand distributions in a reach of the Colorado River below the Little Colorado River, Grand Canyon, Arizona  

USGS Publications Warehouse

A release from Glen Canyon Dam during March-April 1996 was designed to test the effectiveness with which the riparian environment could be renewed with discharges greatly in excess of the normal powerplant-restricted maximum. Of primary concern was the rebuilding of sand deposits along the channel sides that are important to the flora and fauna along the river corridor and that provide the only camp sites for riverside visitors to the Grand Canyon National Park. Analysis of the depositional processes with a model of flow, sand transport, and bed evolution shows that the sand deposits formed along the channel sides early during the high flow were affected only slightly by the decline in suspended-sand concentrations over the course of the controlled flood. Modeling results suggest that the removal of a large sand deposit over several hours was not a response to declining suspended-sand concentrations. Comparisons of the controlled-flood deposits with deposits formed during a flood in January 1993 on the Little Colorado River that contributed sufficient sand to raise the suspended-sand concentrations to predam levels in the main stem show that the depositional pattern as well as the magnitude is strongly influenced by the suspended-sand concentrations.

Wiele, S.M.

1998-01-01

334

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

335

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

336

EXPERIMENTAL AND ENGINEERING SUPPORT FOR THE CAFB (CHEMICALLY ACTIVE FLUID-BED) DEMONSTRATION: RESIDUE DISPOSAL/UTILIZATION  

EPA Science Inventory

The report gives results of an investigation of the disposal and utilization of spent sulfur sorbent from the Chemically Active Fluid-bed (CAFB) process. Lignite ash with a minimum of 10% CaO can be used as a replacement for sand or medium aggregate or as a partial replacement fo...

337

May 2009, Volume 31, Number 2 New Mexico GeoloGy 31 Newly discovered pumice beds in axial-flu-  

E-print Network

May 2009, Volume 31, Number 2 New Mexico GeoloGy 31 Abstract Newly discovered pumice beds in axial. The Lucero pumice in the Doña Ana Mountains is 1­1.5 m thick and consists of granule- and pebble-sized pumice intercalated with fluvial sand, whereas the Mud Springs pumice along the southeastern flank of the Mud Springs

Dunbar, Nelia W.

338

Bed drain cover assembly for a fluidized bed  

DOEpatents

A loose fitting movable cover plate (36), suitable for the severe service encountered in a fluidized bed combustor (10), restricts the flow of solids into the combustor drain lines (30) during shutdown of the bed. This cover makes it possible to empty spent solids from the bed drain lines which would otherwise plug the piping between the drain and the downstream metering device. This enables use of multiple drain lines each with a separate metering device for the control of solids flow rate.

Comparato, Joseph R. (Bloomfield, CT); Jacobs, Martin (Hartford, CT)

1982-01-01

339

Production Mechanisms for the Sand on Titan and the Prospects for a Global Sand Sea  

NASA Astrophysics Data System (ADS)

With ~15% of its surface covered by sand seas, Titan turns out to be the Arrakis of the solar system. How the sand particles that make up the dunes are created, however, remains an outstanding question. Titan's haze particles are organic in composition as required by spectral analysis of dunes, however they have diameters of ~1um, and are 10,000,000 times too small by mass to directly represent the ~200-um sand particles. In addition to previous suggestions that sand could come from sintering of sand particles or by burial, lithification, and subsequent erosion (more like typical sands on Earth), we suggest two new mechanisms for production of sand in association with Titan's liquid reservoirs. Dissolution and reprecipitation as evaporite forms the gypsum dunes of White Sands, NM, USA on Earth, and could play a role on Titan as well. Alternatively, haze particles in the lakes and seas could aggregate into larger particles via flocculation, a mechanism seen to occur on Earth in Morocco. Each of these sand particle production ideas has associated predictions that can be tested by future observations. The lack of evident sand sources in VIMS data implies that Titan's sand seas may be old and their continuous interconnectedness across the Dark Equatorial Belt implies that all of the equatorial dunefields may represent a single compositionally uniform sand sea. We will present possibilities for sands from this sea to bridge the large gap across Xanadu, including barchan chains and fluvial transport.

Barnes, Jason W.; Lorenz, Ralph D.; Radebaugh, Jani; Hayes, Alexander G.; MacKenzie, Shannon

2014-11-01

340

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

341

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

342

Wave-Induced Suspended Sand Transport Around Ripples in the Near Shore Zone  

NASA Astrophysics Data System (ADS)

The importance of the suspended sediment transport by waves implies a strong need to analyse reliably the suspended sediment concentration as the major part of the total wave-induced sediment load in the near shore zone. Sediment entrainment processes due to the oscillatory flow above rippled and plane sea beds are fundamentally different. Above plane sea beds and over short crested 3D ripples, where the sheet flow and the bed load regime respectively dominates, the momentum transfer is primarily caused by turbulent diffusion. In contrast, above a sea bed covered with long crested vortex ripples, the coherent vortex mechanisms due to the flow separation at the steep ripple crests generate sediment-laden vortices in the near-bed zone, which are detached from the ripple crest, ejected into the water column and finally shed at the time of the flow reversal. Experiments with movable sand bed were carried out recently in the Large Wave Flume (GWK) of the Coastal Research Centre (FZK) to model physically the near shore processes associated with the sediment transport above sandy rippled sea beds. The observations were made under regular and irregular waves. Two multi frequency Acoustic Backscatter Systems (ABS), four Optical point Sensors (Optical Turbidity meters) and one Transverse Suction System (TSS) were used to measure the Suspended Sediment Concentrations (SSC), whereas two Electromagnetic Current Meters (ECMs) measured the simultaneous orbital velocity components near the sea bed and 23 pieces wave gauges fitted on the wall side along the entire beach profile recorded the free water surface elevations during each test. A comparative analysis of SSC-measurements using mechanical, optical and acoustical techniques well-illustrates why the acoustic measuring technique (ABS) represents the most appropriate technique for the measurement of the suspension processes, especially over the rippled beds. Moreover, the high-resolution temporal and spatial structures of the intra wave suspension field during a wave cycle around a steep vortex ripple conducted with ABS provided a quantitative evidence of the appropriateness of the acoustical technique to analyse the flow separation, the lee side-vortex generation and the sediment-rich vortex shedding at the time of the flow reversal. In fact, a reliable and detailed description of these mechanisms is extremely important to better understand the temporal and spatial distribution of suspended load, especially above steep ripples, and to develop more physically-based predictive models. This work has been partly supported by European Community's Sixth Framework Program in the Joint Research Activity SANDS, which is a part of the Integrated Infrastructure Initiative HYDRALAB III, Contract no. 022441 (R113) and by the BMBF supported project ModPro.

Ahmari, A.; Oumeraci, H.

2010-12-01

343

Fast fluidized bed steam generator  

DOEpatents

A steam generator in which a high-velocity, combustion-supporting gas is passed through a bed of particulate material to provide a fluidized bed having a dense-phase portion and an entrained-phase portion for the combustion of fuel material. A first set of heat transfer elements connected to a steam drum is vertically disposed above the dense-phase fluidized bed to form a first flow circuit for heat transfer fluid which is heated primarily by the entrained-phase fluidized bed. A second set of heat transfer elements connected to the steam drum and forming the wall structure of the furnace provides a second flow circuit for the heat transfer fluid, the lower portion of which is heated by the dense-phase fluidized bed and the upper portion by the entrained-phase fluidized bed.

Bryers, Richard W. (Flemington, NJ); Taylor, Thomas E. (Bergenfield, NJ)

1980-01-01

344

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

345

Fluidized bed boiler feed system  

DOEpatents

A fluidized bed boiler feed system for the combustion of pulverized coal. Coal is first screened to separate large from small particles. Large particles of coal are fed directly to the top of the fluidized bed while fine particles are first mixed with recycled char, preheated, and then fed into the interior of the fluidized bed to promote char burnout and to avoid elutriation and carryover.

Jones, Brian C. (Windsor, CT)

1981-01-01

346

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

347

Debris-bed friction of hard-bedded glaciers  

USGS Publications Warehouse

[1] Field measurements of debris-bed friction on a smooth rock tablet at the bed of Engabreen, a hard-bedded, temperate glacier in northern Norway, indicated that basal ice containing 10% debris by volume exerted local shear traction of up to 500 kPa. The corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0.05 and 0.08. A model of friction in which nonrotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if the power law exponent for ice flowing past large clasts is 1. A small exponent (n < 2) is likely because stresses in ice are small and flow is transient. Numerical calculations of the bed-normal drag force on a sphere in contact with a flat bed using n = 1 show that this force can reach values several hundred times that on a sphere isolated from the bed, thus drastically increasing frictional resistance. Various estimates of basal friction are obtained from this model. For example, the shear traction at the bed of a glacier sliding at 20 m a-1 with a geothermally induced melt rate of 0.006 m a-1 and an effective pressure of 300 kPa can exceed 100 kPa. Debris-bed friction can therefore be a major component of sliding resistance, contradicting the common assumption that debris-bed friction is negligible. Copyright 2005 by the American Geophysical Union.

Cohen, D.; Iverson, N.R.; Hooyer, T.S.; Fischer, U.H.; Jackson, M.; Moore, P.L.

2005-01-01

348

Fluidized bed deposition of diamond  

DOEpatents

A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

Laia, Jr., Joseph R. (Los Alamos, NM); Carroll, David W. (Los Alamos, NM); Trkula, Mitchell (Los Alamos, NM); Anderson, Wallace E. (Los Alamos, NM); Valone, Steven M. (Santa Fe, NM)

1998-01-01

349

Method for packing chromatographic beds  

DOEpatents

Column chromatography beds are packed through the application of static force. A slurry of the chromatography bed material and a non-viscous liquid is filled into the column plugged at one end, and allowed to settle. The column is transferred to a centrifuge, and centrifuged for a brief period of time to achieve a predetermined packing level, at a range generally of 100-5,000 gravities. Thereafter, the plug is removed, other fixtures may be secured, and the liquid is allowed to flow out through the bed. This results in an evenly packed bed, with no channeling or preferential flow characteristics.

Freeman, David H. (Potomac, MD); Angeles, Rosalie M. (Germantown, MD); Keller, Suzanne (Rockville, MD)

1991-01-01

350

Paleobiology of the Sand Beneath the Valders Diamicton at Valders, Wisconsin  

Microsoft Academic Search

Previously undescribed pollen, plant macrofossils, molluscs, and ostracodes were recovered from a 2.5-m-thick glaciolacustrine unit of silty sand and clay at Valders, Wisconsin. The interstadial sediment was deposited about 12,20014C yr B.P. after retreat of the Green Bay lobe that deposited diamicton of the Horicon Formation, and before advance of the Lake Michigan lobe that deposited the red-brown diamicton of

Louis J. Maher; Norton G. Miller; Richard G. Baker; B. Brandon Curry; David M. Mickelson

1998-01-01

351

Depositional environment of the "stringer sand" member, Lower Tuscaloosa Formation (Cretaceous), Mallalieu field, Mississippi  

E-print Network

of southern Mississippi is generally considered to be of shallow-water marine or deltaic origin. A detailed environmental study of the "stringer sand" member at Mallalieu field indicates a fluvio-deltaic origin. This study was based on megascopic... gray and red shale s. 23 PROCEDURE Megascopic Examination General. Cores from seven wells were examined and described (see Appendix) during this investigation so that the vertical depositional sequence could be determined. Rock properties...

Cook, Billy Charles

2012-06-07

352

An analysis of mussel bed habitats in the Dutch Wadden Sea  

NASA Astrophysics Data System (ADS)

A habitat suitability analysis for littoral mussel beds in the Dutch Wadden Sea was carried out. The analysis was based on the presence of mussel beds in the years 1960-1970, and a number of environmental characteristics: wave action, flow velocity, median grain size, emersion times and distance to a gully border. The habitat model describes mussel bed appearance quantitatively. It predicts the distribution of mussel beds quite well, as well as the distribution of spatfall in the years 1994 and 1996. From the analysis we found that wave action (maximum orbital velocity) was the main structuring factor. A low orbital velocity was preferred. Neither very low, nor maximum flow velocities were favourable for mussel beds. Very coarse sands or silty environments were not preferred. Sites close to the low water line showed lower mussel bed appearance; when emersion time was above 50% , hardly any mussel beds could be found. The habitat suitability analysis and the construction of a habitat suitability map was performed in the framework of the discussions on a further or reduced exploitation of the tidal flats in the Dutch Wadden Sea by cockle and mussel fishery activities.

Brinkman, A. G.; Dankers, N.; van Stralen, M.

2002-04-01

353

Optimisation de la concentration de biomasse dans un réacteur à lit fluidisé Optimization of biomass concentration in a fluidised bed reactor  

Microsoft Academic Search

SUMMARY Fluidized sand-bed, fixed-film denitrifying reactors were tested for the treat- ment of high strength waters and for the optimization and control of biofilm thickness. Two reactors with sand (0.63-0.8 mm) as the carrier particle were operated. Ethanol and propionic acid were used as carbon sources. Nitrate concentrations were in the range of 200-900 mg NOj-N\\/1. Tests showed no substrate

P. MIHÂLTZ; Zs. CSIKOR; P. CHATELUER; B. SIKLÔDI

354

Hazards of mattresses, beds and bedding in deaths of infants.  

PubMed

Of 52 infants who had died suddenly and were referred to autopsy, nine had lain on adult water beds for the first time; five had died as a result of accidents; two had died on water beds; two were in beds with widely spaced slats; and one had died as a result of strangulation. Three deaths were due to overlying. Three other infants had been placed on sheepskin rugs for the first time and were found dead shortly thereafter. These infants ranged in age from 2 to 9 months, except for a severely mentally retarded nine-year-old with spastic paraplegia. We believe that a general warning should be issued concerning water beds and that soft bedding should not be used for infants. Infants should not be placed unattended or left to sleep on water beds; only beds recommended for infants should be used. Overlying of a young infant is most likely to occur on a water bed, or if the parent is obese or has consumed alcohol. PMID:2063814

Gilbert-Barness, E; Hegstrand, L; Chandra, S; Emery, J L; Barness, L A; Franciosi, R; Huntington, R

1991-03-01

355

Pressurized fluidized bed reactor  

DOEpatents

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

Isaksson, J.

1996-03-19

356

Pressurized fluidized bed reactor  

DOEpatents

A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

Isaksson, Juhani (Karhula, FI)

1996-01-01

357

Depositional environment of lower Green River Formation sandstones (Eocene), Red Wash field (Uinta Basin), Uintah County, Utah  

E-print Network

facies changes. This study deals with an interval of several sand facies in the lower part of the Green River Formation in the Red Wash field. The Red Wash field is located in the northeastern part of the Uinta Basin in Uintah County, Utah (Figure 1.... The dominance of fine-grained sediments indicates a fluvial-flood plain origin (Chatfield, 1965). The objectives of this study are to determine the depositional environments of the lower Green River sands in the Red Wash field, determine paleoenvironmental...

McClain, Anthony Scott

2012-06-07

358

Image analysis for measuring the size stratification in sand-gravel laboratory experiments  

NASA Astrophysics Data System (ADS)

Measurements of spatial and temporal changes in the grain-size distribution of the bed surface and substrate are crucial to improving the modelling of sediment transport and associated grain-size selective processes. We present three complementary techniques to determine such variations in the grain-size distribution of the bed surface in sand-gravel laboratory experiments, as well as the resulting size stratification: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratification measurement method was evaluated in two sets of experiments. In both sets three grain-size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, that is, the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e. grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also to the observation and understanding of grain-size selective processes. The size stratification based on areal fractions is measured with sufficient accuracy. Other advantages of the proposed size stratification measurement method are (a) rapid collection and processing of a large amount of data, (b) a very high spatial density of information on the grain-size distribution, (c) the lack of disturbances to the bed surface, (d) only minor disturbances to the substrate due to the removal of sediment layers, and (e) the possibility to return a sediment layer to its original elevation and continue the flume experiment. The areal fractions are converted into volumetric fractions using an existing conversion model.

Orrú, C.; Chavarrías, V.; Uijttewaal, W. S. J.; Blom, A.

2014-04-01

359

Step-wise subglacial deposition and deformation of glaciofluvial sediments along a palaeo-ice stream corridor: glacier bed decoupling-recoupling cycles controlled by basal water pressure.  

NASA Astrophysics Data System (ADS)

Sediment exposures near the margins of a postulated palaeo-ice stream corridor (Baltic Ice Stream) on the Island of Funen, Denmark, reveal a 2.5-4 m thick sequence of stacked and folded glaciofluvial sediments overlain by a 2-3 m thick basal till. Glaciofluvial sediments consist of tabular beds of planar-stratified, massive and cross-stratified sand and gravel with localized channel fills of open-work gravel. These beds exhibit curvilinear sheath folding often leading to eye folds. Sand and gravel beds are typically separated by silty clay beds and laminations recording slackwater deposition within subglacial cavities. Folds frequently display attenuated upper limbs reflecting shearing associated with ice movement. On lower fold limbs, only localized thrusting is observed, suggesting water saturation of sands and gravels during deformation, and relatively low strain rates. Folds are frequently truncated by overlying sand and gravel beds. No evidence of shearing is found along these contacts which are interpreted as erosional surfaces. We propose that glaciofluvial sediments record incremental, step-wise subglacial deposition and deformation rather than wholesale deformation following emplacement of the entire glaciofluvial sequence. Specifically, we envisage that individual beds were deposited and folded subglacially, with deposition occurring during ice-bed decoupling followed by recoupling and shearing of the upper bed surface by the ice base to produce folds with attenuated upper limbs. Silty clay beds helped to maintain elevated porewater pressure by acting as local aquitards. Tabular sand and gravel beds and open work gravel filling scours within single beds suggest broad sheet-like subglacial flows (10-100s m wide) that become increasingly channelized. We propose that the sedimentary sequence records a highly dynamic glaciohydraulic system characterized by repeated localized subglacial cavity development, and storage and release of meltwater leading to glacier decoupling that may have facilitated fast flow of the Baltic Ice Stream. These findings have two important implications for reconstructions of subglacial processes, understanding of rapid ice flow mechanisms, and the sedimentologic criteria used to recognize rapid ice flow in the geologic record: 1) if repeated basal decoupling facilitated rapid ice flow, then the record of this rapid ice flow consists of glaciofluvial sediments. This contrasts strongly with conventional perceptions of ice stream beds, often assumed to be composed of till, and bears on the criteria used to recognize rapid ice flow in the geologic record; 2) extensive glaciofluvial deposition can occur subglacially in sheet-like configurations that are more commonly associated with proglacial environments. Differentiating between sub- and proglacial deposition is critical to palaeoenvironmental reconstructions and inferences of ice sheet dynamics.

Lesemann, Jerome-Etienne; Alsop, G. Ian; Piotrowski, Jan A.

2010-05-01

360

Bedform development in carbonate skeletal sand: Influence of fluid velocity and grain size in flume experiments  

SciTech Connect

The succession of bedform that develops at a given water depth during flow depends not only on flow velocity but also on grain size and characteristics; these relationships, well understood for siliciclastic sediment, have received little attention in the case of carbonate skeletal sediment. Flume experiments were conducted in order to investigate the transport behavior of carbonate skeletal sand under unidirectional flow, with the intent to define the hydraulic conditions for which various bed phases are stable. Transport experiments performed on three different skeletal carbonate sand sizes produced sequences of bed phases nearly identical to those produced in well-rounded quartz sediment, in spite of heterogeneity in both shape and intragranular porosity of carbonate skeletal grains. Overall, bed phases of carbonate skeletal grains developed at lower threshold velocities than for equivalent-sized quartz grains due to both cross-sectional area differences and buoyancy resulting from intragranular porosity. However, the fundamental physical processes that operate during grain transport apparently are invariant with respect to grain composition, geometry, and microarchitecture. An additional consequence of prolonged transport under upper flow regime conditions was the production of carbonate mud, apparently from mechanical abrasion of micrite envelopes and micro-borings on grain surfaces. Stratification features generated by flume experiments resemble those observed in ancient carbonate packstone and grainstone deposits.

Corbin, M.C.; Driese, S.G.; Broadhead, T.W. (Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences)

1992-01-01

361

Sun glitter imaging analysis of submarine sand waves in HJ-1A/B satellite CCD images  

NASA Astrophysics Data System (ADS)

Submarine sand waves are a widespread bed-form in tidal environment. Submarine sand waves induce current convergence and divergence that affect sea surface roughness thus become visible in sun glitter images. These sun glitter images have been employed for mapping sand wave topography. However, there are lots of effect factors in sun glitter imaging of the submarine sand waves, such as the imaging geometry and dynamic environment condition. In this paper, several sun glitter images from HJ-1A/B in the Taiwan Banks are selected. These satellite sun glitter images are used to discuss sun glitter imaging characteristics in different sensor parameters and dynamic environment condition. To interpret the imaging characteristics, calculating the sun glitter radiance and analyzing its spatial characteristics of the sand wave in different images is the best way. In this study, a simulated model based on sun glitter radiation transmission is adopted to certify the imaging analysis in further. Some results are drawn based on the study. Firstly, the sun glitter radiation is mainly determined by sensor view angle. Second, the current is another key factor for the sun glitter. The opposite current direction will cause exchanging of bright stripes and dark stripes. Third, brightness reversal would happen at the critical angle. Therefore, when using sun glitter image to obtain depth inversion, one is advised to take advantage of image properties of sand waves and to pay attention to key dynamic environment condition and brightness reversal.

Zhang, Huaguo; He, Xiekai; Yang, Kang; Fu, Bin; Guan, Weibing

2014-11-01

362

Sedimentary processes associated with sand and boulder deposits formed by the 2011 Tohoku-oki tsunami at Sabusawa Island, Japan  

NASA Astrophysics Data System (ADS)

This paper reports on the sedimentary processes of sand and boulder deposition at Sabusawa Island, Japan as a result of the 2011 Tohoku-oki tsunami. Boulders were composed of tuffaceous rocks and sourced from an earthquake-triggered slope failure as well as concrete fragments of seawall. They were scattered over the ground surface and did not form boulder ridges, although there was some local imbrication. The boulders were deposited on top of a sand layer indicating that the latter, possibly deposited from bed load, covered the ground surface first. This sand layer probably reduced friction allowing boulders to be transported more easily than might be expected across a hard ground with a high bottom friction. Sand deposits showed landward thinning and fining features, while the boulders showed a landward coarsening (tuffaceous boulders) or a landward fining (concrete boulders), indicating that large clasts were not necessarily scattered randomly but rather might have a clast size gradient with distance inland. These features are explained by the local topographic setting that constrained the directions of incoming and returning tsunami flows. Some clasts at the inland extent of the boulder field were covered by an upward fining sand layer. This feature suggests that the boulders were deposited prior to the suspended sands, with the latter subsequently laid down before the water level dropped below the top of the boulders. Such modern investigations of the sedimentary features of various sizes of grains and clasts immediately after a tsunami provide invaluable data for the reconstruction of inundation processes.

Goto, Kazuhisa; Sugawara, Daisuke; Ikema, Satoko; Miyagi, Toyohiko

2012-12-01

363

Carbon attrition during the circulating fluidized bed combustion of a packaging-derived fuel  

SciTech Connect

Cylindrical pellets of a market-available packaging-derived fuel, obtained from a mono-material collection of polyethylene terephthalate (PET) bottles, were batchwise fed to a laboratory scale circulating fluidized bed (CFB) combustor. The apparatus, whose riser was 41 mm ID and 4 m high, was operated under both inert and oxidizing conditions to establish the relative importance of purely mechanical attrition and combustion-assisted attrition in generating carbon fines. Silica sand particles of two size distributions were used as inert materials. For each run, carbon load and carbon particle size distribution in the riser and rates of attrited carbon fines escaping the combustor were determined as a function of time. A parallel investigation was carried out with a bubbling fluidized bed (BFB) combustor to point out peculiarities of attrition in CFB combustors. After devolatilization, PET pellets generated fragile aggregates of char and sand, which easily crumbled, leading to single particles, partially covered by a carbon-rich layer. The injected fixed carbon was therefore present in the bed in three phases: an A-phase, made of aggregates of sand and char, an S-phase, made of individual carbon-covered sand particles and an F-phase, made of carbon fines, abraded by the surfaces of the A- and S-phases. The effects of the size of inert material on the different forms under which fixed carbon was present in the bed and on the rate of escape of attrited carbon fines from the combustor were investigated. Features of carbon attrition in CFB and BFB combustors are discussed.

Mastellone, M.L. [Univ. Federico II of Naples, Napoli (Italy). Dept. of Chemical Engineering] [Univ. Federico II of Naples, Napoli (Italy). Dept. of Chemical Engineering; Arena, U. [National Research Council, Napoli (Italy). Inst. for Combustion Research] [National Research Council, Napoli (Italy). Inst. for Combustion Research; [Univ. of Naples, Caserta (Italy). Dept. of Environmental Sciences

1999-05-01

364

Ultrafine Ash Particle Formation During Waste Sludge Incineration in Fluidized Bed Reactors  

Microsoft Academic Search

Ash formation during the bubbling fluidized bed (BFB) combustion of bark and pulp mill sludge has been studied on an industrial and bench scale. During co-firing in an industrial BFB a submicron fly ash mode was formed via condensation of volatilized K, Na, Sand Cl species at 0.05–0.3 ?m. The submicron mass mode below 0.3 ?m made up 2.2–5.0% of

J. L. SOMPPI; E. I. KAUPPINEN; J. KURKELA; U. TAPPER; M. ÖHMAN; A. NORDIN; B. JOHANSON

1998-01-01

365

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

366

NEARSHORE SAND SOURCES FOR AMERICAN SAMOA: AN ALTERNATIVE TO USING BEACH SAND.  

USGS Publications Warehouse

Using a combination of geophysical techniques, in situ observations, and sampling by scuba divers, we investigated along the south shore of Tutuila Island, American Samoa, for nearshore sand deposits. To minimize the impact of future sand dredging on the island's littoral sediments, the search took place in a narrow zone between the outside of the fringing reef and the 30-m bathymetric contour. Because the sand will be used by the Samoans in a variety of ways, an area high in siliciclastic sand - Nua-Se'etaga Bay - and two areas containing only carbonate sand - Faga'itua Bay and Nafanua Bank - were inspected in detail. Results of the exploration program are discussed.

Dingler, John R.; Reiss, Thomas E.

1987-01-01

367

Elastic properties of unconsolidated porous sand reservoirs  

Microsoft Academic Search

The effect of compressive stress and pore fluid properties on elastic properties of unconsolidated sand reservoirs was determined by laboratory velocity and pore volume measurements on two specimens. These consisted of a naturally occurring very fine grained sand and glass beads, each with a porosity of approximately 38 percent. Compressional- and shear-wave velocities and pore compressibility were measured in the

S. N. Domenico

1977-01-01

368

NEW DEVELOPMENTS IN SLOW SAND FILTRATION  

EPA Science Inventory

Recent regulations promulgated by the U.S. Environmental Protection Agency (EPA), including the Surface Water Treatment Rule, have helped to renew the interest in the use of slow sand filtration (SSF) for treating surface waters for small communities. low sand filtration is not a...

369

Introduction to Exploring Sand and Water  

ERIC Educational Resources Information Center

What happens when children pour water through a funnel? They begin to understand science and math concepts such as flow, force, gravity, and volume. What happens when children mold sand to create a tunnel? They develop skills in areas such as problem solving and predicting. They also gain knowledge about absorption and the properties of sand and…

Early Childhood Today, 2006

2006-01-01

370

... Forward............. 1 Sand and Salt: A  

E-print Network

Contents The Road ... Forward............. 1 Sand and Salt: A Model for Change... 2 Commonly Used, without Sand and Salt: A Model for Change Duane `Dewey'Amsler, Circuit Rider, Cornell Local Roads Program_and_nibbles The Road ... Forward David P. Orr, PE, Director / Senior Engineer, Cornell Local Roads Program Only you can

Walter, M.Todd

371

Onsite Wastewater Treatment Systems: Sand Filters  

E-print Network

: ? Intermittent sand filter, in which wastewater is applied periodically to a 24- to 36-inch- Bruce Lesikar Professor and Extension Agricultural Engineer The Texas A&M System Wastewater applied to the sand filter should be pretreated, such as in a septic...

Lesikar, Bruce J.

2008-10-23

372

White Sands National Monument: Education Fact Sheets  

NSDL National Science Digital Library

This National Park Service website contains the following reference sections: Where Does All the Sand Come From?, Animals of the Desert, How Do Sand Dunes Move?, and Plants of the Dune Field. There are recommended reading lists for students from preschool to high school interested in pursuing these topics further.

373

Influence of the bank vegetation on the river bed variations  

NASA Astrophysics Data System (ADS)

In the natural rivers, woody vegetation commonly grows along the riverbank. When flood flows run through the woody vegetation zones, the stream processes are markedly affected. This study experimentally discusses the characteristics of flow fields and the changes of river bedform while water flows through woody vegetation zones. The experiments were produced in a flume with 20m long, 1m wide, and a fixed slope of 0.001. The woody vegetation was set in 10 square centimeters at one side of the flume. Experimental vegetation was simulated by the steel columns due to the stem of emergent woody vegetation near bed is rigid. The experimental flow was steady and flow velocity was adopted to near the critical flow for the initiation of sediment motion. Uniform sand with a median size of 0.88 mm was used as the bed sediment. The three dimensional flow fields of time-averaged velocity distributions and turbulent characteristics were measured by an Acoustic Doppler Velocimeter(ADV). The bed morphology of equilibrium scour condition was measured by a Laser Distance Meter. The interactions between water flows and river bed with vegetation ware investigated by observing the scour and deposition processes around the vegetation zone. In addition, the flow fields at flat bed and equilibrium scour conditions are measured separately. Furthermore, the influence of vegetation density on the flow and bedform was investigated by using the present experiment. When the flows passed through the vegetation zones, the approaching flow was retarded by the vegetation zone along the vegetation-bank side and accelerated in the main channel. The flow velocities also reduced downstream of the vegetation zones and the water depths dropped significantly in the streamwise direction. It was observed that the levels of the sediment deposition decreased at downstream of the vegetation zones as the vegetation density increased. Near the vegetation zone, the size of the scour hole increased as the vegetation density increased.

Ruei Ke, Bo; Chan, Hsun-Chuan; Chen, You-Cheng

2014-05-01

374

Fluidized-bed-combustor modeling  

Microsoft Academic Search

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 SOâ by limestone in the bed. The model is

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

1977-01-01

375

Pulsed atmospheric fluidized bed combustion  

SciTech Connect

The general specifications for a Pulsed Atmospheric Fluidized Bed Combustor Design Report (PAFBC) plant are presented. The design tasks for the PAFBC are described in the following areas: Coal/Limestone preparation and feed system; pulse combustor; fluidized bed; boiler parts; and ash handling system.

Not Available

1992-08-01

376

LSP Composite Test Bed Design  

NASA Technical Reports Server (NTRS)

This document provides standalone information for the Lightning Strike Protection (LSP) Composite Substrate Test Bed Design. A six-sheet drawing set is reproduced for reference, as is some additional descriptive information on suitable sensors and use of the test bed.

Day, Arthur C.; Griess, Kenneth H.

2013-01-01

377

UMore Park Sand and Gravel Resources Project University of Minnesota  

E-print Network

UMore Park Sand and Gravel Resources Project University of Minnesota Public Comment Forum and Open ­ Steven Lott, Co-project manager, UMore Park Sand and Gravel Resources Project 6:40 The UMore Park Sand

Netoff, Theoden

378

Pulling a patient up in bed  

MedlinePLUS

... may slowly slide when the person is in bed for a long time. The person may ask ... Moving a patient in bed ... You must move or pull someone up in bed the right way to avoid injuring the patient's ...

379

Altitude of the top of the Sparta Sand and Memphis Sand in three areas of Arkansas  

USGS Publications Warehouse

The Sparta Sand and Memphis Sand form the second most productive aquifer in Arkansas. The Sparta Sand and Memphis Sand range in thick- ness from 0 to 900 feet, consisting of fine- to medium-grained sands interbedded with layers of silt, clay, shale, and minor amounts of lignite. Within the three areas of interest, the top surface of the Sparta Sand and Memphis Sand dips regionally east and southeast towards the axis of the Mississippi Embayment syncline and Desha Basin. Local variations in the top surface may be attributed to a combination of continued development of structural features, differential compaction, localized faulting, and erosion of the surface prior to subsequent inundation and deposition of younger sediments.

Pugh, Aaron L.; Westerfield, Paul W.; Gonthier, Gerard J.; Poynter, David T.

1998-01-01

380

Generalized thickness of the surficial deposits above the confining bed overlying the Floridan Aquifer, Southwest Florida Water Management District  

USGS Publications Warehouse

This map report presents the thickness of the surficial deposits overlying the upper confining bed of the Floridan aquifer in the Southwest Florida Water Management District. The surficial deposits range in thickness from less than 25 feet in the western part of the district to greater than 250 feet in the eastern part. The surficial deposits include sand, clayey sand, shell, and shelly marl that occur in the Holocene sand, Pleistocene marine terrace sand, and unconsolidated parts of the Fort Thompson Formation, Caloosahatchee Marl, Alachua Formation, and Bone Valley Formation. Lithologic logs and information from quarries were used in conjunction with an unpublished map prepared during an earlier investigation to compile this map at 1:250,000 scale. (Kosco-USGS)

Wolansky, R.M.; Spechler, R.M.; Buono, Anthony

1979-01-01

381

Dynamic bed reactor  

DOEpatents

A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix.

Stormo, Keith E. (Moscow, ID)

1996-07-02

382

A rapid compatibility analysis of potential offshore sand sources for beaches of the Santa Barbara Littoral Cell  

USGS Publications Warehouse

The beaches of the Santa Barbara Littoral Cell, which are narrow as a result of either natural and/or anthropogenic factors, may benefit from nourishment. Sand compatibility is fundamental to beach nourishment success and grain size is the parameter often used to evaluate equivalence. Only after understanding which sand sizes naturally compose beaches in a specific cell, especially the smallest size that remains on the beach, can the potential compatibility of source areas, such as offshore borrow sites, be accurately assessed. This study examines sediments on the beach and in the nearshore (5-20m depth) for the entire Santa Barbara Littoral Cell east of Point Conception. A digital bed sediment camera, the Eyeball??, and spatial autocorrelation technique were used to determine sediment grain size. Here we report on whether nearshore sediments are comparable and compatible with beach sands of the Santa Barbara Littoral Cell. ?? 2007 ASCE.

Mustain, N.; Griggs, G.; Barnard, P.L.

2007-01-01

383

Lifeguarding American Red Cross  

E-print Network

Lifeguarding Manual #12;American Red Cross Lifeguarding Manual The following organizations provided review of the materials and/or support American Red Cross Lifeguarding: #12;This manual is part of the American Red Cross Lifeguarding program. By itself, it does not constitute complete and comprehensive

Carter, John

384

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 ...

385

Regional transport of a chemically distinctive dust: Gypsum from White Sands, New Mexico (USA)  

NASA Astrophysics Data System (ADS)

The White Sands complex, a National Monument and adjoining Missile Range in southern New Mexico, occupies the dry bed of an ice-age lake where an active gypsum dunefield abuts erodible playa sediments. Aerosols entrained from White Sands are sometimes visible on satellite images as distinct, light-colored plumes crossing the Sacramento Mountains to the east and northeast. The IMPROVE network (Interagency Monitoring of PROtected Visual Environments) operates long-term aerosol samplers at two sites east of the Sacramento range. In recent years a spring pulse of sulfate aerosol has appeared at these sites, eclipsing the regional summer peak resulting from atmospheric reactions of sulfur dioxide emissions. A significant fraction of this spring sulfate is contributed by gypsum and other salts from White Sands, with much of the sulfur in coarse particles and concentrations of calcium and strontium above regional levels. The increase in these gypsiferous species coincides with a drought following a period of above-average precipitation. White Sands and the IMPROVE samplers together provide a natural laboratory: a climatically sensitive dust source that is both well characterized and chemically distinct from its surroundings, with a signature that remains identifiable at long-term observatories 100-200 km downwind.

White, Warren H.; Hyslop, Nicole P.; Trzepla, Krystyna; Yatkin, Sinan; Rarig, Randy S.; Gill, Thomas E.; Jin, Lixin

2015-03-01

386

Scales of geological heterogeneity of a deep-water sand giant oil field  

SciTech Connect

To understand the levels of accuracy that can be placed upon different scales of reservoir description, turbidite intervals in part of the giant Wilmington oil field, California, have been numerically described at four scales of heterogeneity. The degree of accuracy of the description, in terms of real geologic variability, is found to diminish with increasing scale. At the microscale (grains and pores) and mesoscale (near well bore), the following flow units, listed in order of decreasing reservoir quality, were defined by relating various geologic and petrophysical properties: thick-bedded sand, thin-bedded sand, and shale. Mutual relationships among the geologic and petrophysical properties are a result of primary depositional processes. At the macroscale (interwell), shale beds are laterally continuous over long distances and probably isolate individual sands by acting as vertical permeability barriers. Petrophysical properties, such as permeability, vary between wells within an order of magnitude of measured values. The relationships among petrophysical properties and geologic properties established at the single-well scale are sometimes but not always predictable between wells. At the megascale (field wide), the turbidites were placed within the context of Vail's integrated sequence stratigraphy model, Walker's progradational submarine fan model, and Mutti's turbidite systems model to illustrate that there is not a unique interpretation when the overall size of a depositional system is larger than that of the data grid. At this scale, petrophysical properties are averaged over a large stratigraphic interval so that there is very little interwell predictability; however, the primary depositional control on gross petrophysical properties is maintained.

Slatt, R.M. (ARCO Oil and Gas Co., Plano, TX (USA)); Phillips, S. (ARCO Alaska, Inc., Anchorage (USA)); Boak, J.M. (Dept. of Energy, Washington, DC (USA)); Lagoe, M.B. (Univ. of Texas, Austin (USA))

1990-05-01

387

Fluidized bed gasification of waste-derived fuels  

SciTech Connect

Five alternative waste-derived fuels obtained from municipal solid waste and different post-consumer packaging were fed in a pilot-scale bubbling fluidized bed gasifier, having a maximum feeding capacity of 100 kg/h. The experimental runs utilized beds of natural olivine, quartz sand or dolomite, fluidized by air, and were carried out under various values of equivalence ratio. The process resulted technically feasible with all the materials tested. The olivine, a neo-silicate of Fe and Mg with an olive-green colour, has proven to be a good candidate to act as a bed catalyst for tar removal during gasification of polyolefin plastic wastes. Thanks to its catalytic activity it is possible to obtain very high fractions of hydrogen in the syngas (between 20% and 30%), even using air as the gasifying agent, i.e. in the most favourable economical conditions and with the simplest plant and reactor configuration. The catalytic activity of olivine was instead reduced or completely inhibited when waste-derived fuels from municipal solid wastes and aggregates of different post-consumer plastic packagings were fed. Anyhow, these materials have given acceptable performance, yielding a syngas of sufficient quality for energy applications after an adequate downstream cleaning.

Arena, Umberto, E-mail: umberto.arena@unina2.i [Department of Environmental Sciences, Second University of Naples, Via A. Vivaldi, 43, 81100 Caserta (Italy); AMRA s.c. a r.l., Via Nuova Agnano, 11, 80125 Napoli (Italy); Zaccariello, Lucio [Department of Environmental Sciences, Second University of Naples, Via A. Vivaldi, 43, 81100 Caserta (Italy); Mastellone, Maria Laura [Department of Environmental Sciences, Second University of Naples, Via A. Vivaldi, 43, 81100 Caserta (Italy); AMRA s.c. a r.l., Via Nuova Agnano, 11, 80125 Napoli (Italy)

2010-07-15

388

Deccan Bole Beds: Mineral magnetism, interpretation and genesis  

NASA Astrophysics Data System (ADS)

Deccan volcanism is one of the most celebrated continental flood volcanism and has been widely studied for its time constrains, duration and K-T mass extinction. Bole beds in Deccan volcanism delineates the hiatus in successive lava flows and are spectator of the extensive volcanism. Bole beds (composed of clays and volcanic ashes) are considered as the weathering products of the older neighboring lava flows and are trapped by younger lava flow. Field occurrences shows common red color for bole beds but occurs in a wide range from brown to green colors. Different color bole beds of DVP have been studied for their Field characteristics, Magnetic susceptibility (MS), Anhysteretic remanent magnetization (ARM), Isothermal remanent magnetization (IRM) and Temperature-susceptibility (k-t) variations. A unique combination of high magnetic susceptibility (?lf), frequency dependent susceptibility (?fd %) and remanence coercivities [B0(CR)] in the red boles mark the significant presence of the finer/SP antiferromagnetic fraction explained here as oxidative baking product of the weathered basaltic sediment enriched in clay. The ultrafine hematite producing red coloration is characteristically of re-deposited pigmentary nature. The high reversibility k-t relation amongst red boles further substantiates their pre-heated nature up to ~ 700 degree Celsius and no significant addition/alteration of iron oxides after re-deposition. The [B0(CR)] for brown boles fall in the range of hard ferrimagnets (40 to 50 mT) and that for the green boles typically show softer or multi-domain (MD) nature (majority of <15mT with rare in the range of 30 to 40 mT). The presence of harder ferrimagnets [single-domain (SD) magnetites] in the brown boles proposes the authigenic (lacustrine) conditions in support of field characters. The green boles representing detrital ferrimagnets (larger/soft MD particles) is in accordance with their field occurrences of infilling, infiltration or detrital nature of deposition. The present study conducted over a variety of field occurrences within the Deccan Volcanic Province infer predominance of detrital processes governed by laterally migrating shallow channels and surface water run-off due to precipitation. Infiltration into fragmentary tops of the basalt bedrocks with baked/unbaked (red/brown bole) sediments; and the infilling into vugs and interstices is characteristics of green boles representing the less oxidative preservations. This resulted into a variety of depositional environments from ephemeral stream to floodplain ponding condtions. The study does not favour any significant pedogenesis or paleo-lateratization process representing a significant interval of non-deposition as proposed by previous work.

Srivastava, P.; Sangode, S. J.; Gudadhe, S. S.; Meshram, D. C.

2012-12-01

389

Pulse enhanced fluidized bed combustion  

SciTech Connect

Various technologies are available for the combustion of high-sulfur, high-ash fuels, particularly coal. From performance, economic and environmental standpoints, fluidized bed combustion (FBC) is the leading candidate for utilization of high sulfur coals. ThermoChem, Inc., and the South Carolina Energy Research and Development Center (SCERDC) are installing a hybrid fluidized bed combustion system at Clemson University. This hybrid system, known as the Pulsed Atmospheric Fluidized Bed Combustor (PAFBC), will augment the University`s steam system by providing 50--60,000 lbs/hr of saturated process steam. The PAFBC, developed by Manufacturing and Technology Conversion International, Inc., (MTCI), integrates a pulse combustor with a bubbling-bed-type atmospheric fluidized bed coal combustor. The pulse combustion system imparts an acoustic effect that enhances combustion efficiency, SO{sub 2} capture, low NO{sub x} emissions, and heat transfer efficiency in the fluidized bed. These benefits of pulse combustion result in modestly sized PAFBC units with high throughput rates and lower costs when compared to conventional fluidized bed units.

Mueller, B.; Golan, L. [South Carolina Energy Research and Development Center, Clemson, SC (United States); Toma, M.; Mansour, M. [Manufacturing and Technology Conversion International, Inc., Columbia, MD (United States)

1996-12-31

390

Particle pressures in fluidized beds  

SciTech Connect

This is an experimental project to make detailed measurements of the particle pressures generated in fluidized beds. The focus lies in two principle areas: (1) the particle pressure distribution around single bubbles rising in a two-dimensional gas-fluidized bed and (2) the particle pressures measured in liquid-fluidized beds. This first year has largely been to constructing the experiments The design of the particle pressure probe has been improved and tested. A two-dimensional gas-fluidized bed has been constructed in order to measure the particle pressure generated around injected bubbles. The probe is also being adapted to work in a liquid fluidized bed. Finally, a two-dimensional liquid fluidized bed is also under construction. Preliminary measurements show that the majority of the particle pressures are generated in the wake of a bubble. However, the particle pressures generated in the liquid bed appear to be extremely small. Finally, while not directly associated with the particle pressure studies, some NERSC supercomputer time was granted alongside this project. This is being used to make large scale computer simulation of the flow of granular materials in hoppers.

Campbell, C.S.; Rahman, K.; Hu, X.; Jin, C.; Potapov, A.V.

1992-01-01

391

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.

392

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

393

Critical State of Sand Matrix Soils  

PubMed Central

The Critical State Soil Mechanic (CSSM) is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, ?, and ?. The range of the value of M, ?, and ? is 0.803–0.998, 0.144–0.248, and 1.727–2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated. PMID:24757417

Marto, Aminaton; Tan, Choy Soon; Makhtar, Ahmad Mahir; Kung Leong, Tiong

2014-01-01

394

Community structure and spatial variation of benthic invertebrates associated with Zostera marina (L.) beds in the northern Baltic Sea  

NASA Astrophysics Data System (ADS)

The distribution and bed structure of eelgrass ( Zostera marina L.), and its importance for associated faunal communities in the coastal areas of the northern Baltic Sea are poorly known. The spatial distribution of the fauna associated with Zostera was studied at five localities in SW Finland in 1993-1994. Zostera was common on all localities, but the beds varied in terms of area (1-5 m diameter), density (50-500 shoots/m 2) and blade length (20-110 cm). A total of about 40 species or taxa were recorded. The zoobenthic infauna showed significant spatial differences, and total abundance and species diversity were significantly higher in the Zostera beds than in adjacent bare sand. The total abundance in Zostera ranged from 25 000 to 50 000 ind/m 2 and in sand from 2500 to 15 000 ind/m 2 The mean number of species in Zostera ranged from 5.9 to 8.8 spp ( H' = 1.76-2.54) and in sand from 2.2 to 5.5 spp ( H' = 1.67-2.31). The epifauna in Zostera was numerically dominated by grazing gastropods (Hydrobiidae) and copepods. The epifauna is an important community component, which contributes to the total diversity of the Zostera assemblage. These systems are among the most species-rich components of the shallow soft-bottom ecosystems in the northern Baltic Sea. The mechanisms structuring both the Zostera and the ambient sand-bottom habitats are presented.

Boström, Christoffer; Bonsdorff, Erik

1997-05-01

395

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

USGS Publications Warehouse

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

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

1988-01-01

396

Fecal indicators in sand, sand contact, and risk of enteric illness among beachgoers  

PubMed Central

Background Beach sand can harbor fecal indicator organisms and pathogens, but enteric illness risk associated with sand contact remains unclear. Methods In 2007, visitors at two recreational marine beaches were asked on the day of their visit about sand contact. Ten to 12 days later, participants answered questions about health symptoms since the visit. F+ coliphage, Enterococcus, Bacteroidales, fecal Bacteroides, and Clostridium spp. in wet sand were measured using culture and molecular methods. Results We analyzed 144 wet sand samples and completed 4,999 interviews. Adjusted odds ratios (aORs) were computed, comparing those in the highest tertile of fecal indicator exposure with those who reported no sand contact. Among those digging in sand compared with those not digging in sand, a molecular measure of Enterococcus spp. (calibrator cell equivalents/g) in sand was positively associated with gastrointestinal (GI) illness (aOR = 2.0 [95% confidence interval (CI) = 1.2–3.2]) and diarrhea (2.4 [1.4–4.2]). Among those buried in sand, point estimates were greater for GI illness (3.3 [1.3–7.9]) and diarrhea (4.9 [1.8–13]). Positive associations were also observed for culture-based Enterococcus (colony-forming units/g) with GI illness (aOR digging = 1.7 [1.1–2.7]) and diarrhea (2.1 [1.3–3.4]). Associations were not found among non-swimmers with sand exposure. Conclusions We observed a positive relationship between sand contact activities and enteric illness as a function of concentrations of fecal microbial pollution in beach sand. PMID:22157306

Heaney, Christopher D.; Sams, Elizabeth; Dufour, Alfred P.; Brenner, Kristen P.; Haugland, Richard A.; Chern, Eunice; Wing, Steve; Marshall, Stephen; Love, David C.; Serre, Marc; Noble, Rachel; Wade, Timothy J.

2011-01-01

397

Invasive plants on disturbed Korean sand dunes  

NASA Astrophysics Data System (ADS)

The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused by invasive plants. The relationships between the degree of invasion and 14 environmental variables were studied. Plots of sand dunes along line transects perpendicular to the coastal lines were established to estimate vegetative species coverage. TWINSPAN (Two-Way Indicator Species Analysis), CCA (Canonical Correspondence Analysis), and DCCA (Detrended Canonical Correspondence Analysis) were performed to classify communities on sand dunes and assess species composition variation. Carex kobomugi, Elymus mollis, and Vitex rotundifolia were found to be the dominant species plotted on the east, the west, and the peripheral coasts of Cheju Island, respectively. Vegetation on the south coast was totally extinct. The 19 communities, including representative C. kobomugi, C. kobomugi- Ixeris repens, C. kobomugi- Oenothera biennis, E. mollis, Lolium multiflorum- Calystegia soldanella, and V. rotundifolia- C. kobomugi, were all classified according to TWINSPAN. Oenothera biennis and L. multiflorum were exotics observed within these native communities. CCA showed that invasive native and exotic species distribution was segregated significantly, according to disturbance level, exotic species number, gravel, sand and silt contents, as well as vegetation size. It further revealed that human disturbance can strongly favor the settlement of invasive and exotic species. Restoration options to reduce exotic plants in the South Korean sand dune areas were found to be the introduction of native plant species from one sand dune into other sand dune areas, prohibition of building and the introduction of exotic soils, and conservation of surrounding sand dune areas.

Kim, Kee Dae

2005-01-01

398

Skin friction for steel piles in sand  

E-print Network

Skin Friction Versus Pile Movement. Test Pile 1 Loaded in Tension 17 10. Skin Friction-Soil Shear Strength Ratio Versus Pile Movement. Compression Test Pile 1 21 Skin Friction-Soil Sheer Strength Ratio Versus Pile Movement. Tension Test Pile 1 22... Data 35 16. 17. Mohr Envelope for Firm Saturated Sand. Mohr Envelope for Dense Saturated Sand. 37 LIST OF FIGURES (Continued) Figure Skin Friction-Soil Shear Strength Ratio Versus Pile Movement for Firm Saturated Sand 39 19. Skin F iction...

Sulaiman, Ibrahim Hikmat

2012-06-07

399

Character of shell beds flanking Herod Point shoal, southeastern Long Island Sound, New York  

USGS Publications Warehouse

High biogenic productivity, strong tidal currents, shoal topography, and short transport distances combine to favor shell-bed formation along the lower flanks of a cape-associated shoal off Herod Point on Long Island, New York. This shell bed has a densely packed, clast-supported fabric composed largely of undegraded surf clam (Spisula solidissima) valves. It is widest along the central part of the western flank of the shoal where topographic gradients are steep and a stronger flood tide results in residual flow. The bed is narrower and thinner toward the landward margins where currents are too weak to transport larger valves and topographic gradients are gentle, limiting bed-load transport mechanisms by which the shells are concentrated. Reconnaissance mapping off Roanoke Point suggests that shell beds are also present at the other cape-associated shoals off northeastern Long Island, where relatively similar geomorphic and oceanographic conditions exist. These shell beds are important to the Long Island Sound ecosystem because they provide complex benthic habitats of rough and hard substrates at the boundary between the muddy basin floor and mobile sand of the shoals. ?? 2011, the Coastal Education & Research Foundation (CERF).

Poppe, L.J.; Williams, S.J.; Babb, Ivar G.

2011-01-01

400

Fluvial processes and local lithology controlling abundance, structure, and composition of mussel beds.  

PubMed

In the Salmon River Canyon, Idaho, the fresh-water pearl mussel, Margaritifera falcata, attains maximum density and age in river reaches where large block-boulders structurally stabilize cobbles and interstitial gravels. We hypothesize that block-boulders prevent significant bed scour during major floods, and these boulder-sheltered mussel beds, although rare, may be critical for population recruitment elsewhere within the river, especially after periodic flood scour of less protected mussel habitat. Mussel shells in Indian middens adjacent to these boulder-stabilized areas suggest that prehistoric tribes selectively exploited the high-density old-aged mussel beds. Locally, canyon reaches are aggrading with sand and gravel, and M. falcata is being replaced by Gonidea angulata. PMID:16593208

Vannote, R L; Minshall, G W

1982-07-01

401

Combustion of peanut and tamarind shells in a conical fluidized-bed combustor: a comparative study.  

PubMed

Combustion of peanut and tamarind shells was studied in the conical fluidized-bed combustor using alumina sand as the bed material to prevent bed agglomeration. Morphological, thermogravimetric and kinetic characteristics were investigated to compare thermal and combustion reactivity between the biomass fuels. The thermogravimetric kinetics of the biomasses was fitted using the Coats-Redfern method. Experimental tests on the combustor were performed at 60 and 45 kg/h fuel feed rates, with excess air within 20-80%. Temperature and gas concentrations were measured along radial and axial directions in the reactor and at stack. The axial temperature and gas concentration profiles inside the combustor exhibited sensible effects of fuel properties and operating conditions on combustion and emission performance. High (? 99%) combustion efficiency and acceptable levels of CO, CxHy, and NO emissions are achievable when firing peanut shells at excess air of about 40%, whereas 60% is more preferable for burning tamarind shells. PMID:23693147

Kuprianov, Vladimir I; Arromdee, Porametr

2013-07-01

402

Fluvial processes and local lithology controlling abundance, structure, and composition of mussel beds  

PubMed Central

In the Salmon River Canyon, Idaho, the fresh-water pearl mussel, Margaritifera falcata, attains maximum density and age in river reaches where large block-boulders structurally stabilize cobbles and interstitial gravels. We hypothesize that block-boulders prevent significant bed scour during major floods, and these boulder-sheltered mussel beds, although rare, may be critical for population recruitment elsewhere within the river, especially after periodic flood scour of less protected mussel habitat. Mussel shells in Indian middens adjacent to these boulder-stabilized areas suggest that prehistoric tribes selectively exploited the high-density old-aged mussel beds. Locally, canyon reaches are aggrading with sand and gravel, and M. falcata is being replaced by Gonidea angulata. PMID:16593208

Vannote, Robin L.; Minshall, G. Wayne

1982-01-01

403

Injection-attachment of Methylosinus trichosporium OB3b in a two-dimensional miniature sand-filled aquifer simulator  

NASA Astrophysics Data System (ADS)

For some potentially useful and emerging in situ bioremediation technologies it is important to control bacterial attachment to subsurface materials during the injection of microbial cell suspensions. In this study the attachment patterns of Methylosinus trichosporium OB3b were measured after horizontal injections into a two-dimensional miniature aquifer simulator containing a wet homogeneous sand. In preliminary sand column assays, bacterial attachment to the sand was increased nearly 2 orders of magnitude compared to attachment in the presence of distilled water by raising the concentration of a pH 7.0 sodium-potassium phosphate buffer to 10 mM. The maximal concentration of attached cells was ˜4×108 cells/g dry sand with both sand minicolumns and the wet sand aquifer simulator. For the latter this occurred on streamlines directly between the horizontal injector and withdrawal ports, where injection-withdrawal velocities were the highest. The effects of a simulated groundwater cross flow during suspension injection on bacterial attachment to the aquifer simulator sands were also studied, and a peristaltic pumping method to counteract these groundwater flow effects resulted in a more localized pattern, i.e., without extensive downstream skewing of the bacterial attachment zone. Phenol red was utilized as a nonbinding, red-colored tracer compound. It proved to be very convenient for quantitatively measuring the earlier breakthroughs of cells versus an inert tracer during the aquifer simulator and subsequent capillary tube cell injection experiments and also for visualizing the anticipated boundaries of cell attachment in the aquifer simulator. The effect of injection velocity on the observed bacterial attachment patterns in these experiments appears to be accounted for by colloid filtration theory.

Shonnard, D. R.; Taylor, R. T.; Hanna, M. L.; Boro, C. O.; Duba, A. G.

1994-01-01

404

Effects of red clover decomposition on phytotoxicity to wild mustard seedling growth  

Microsoft Academic Search

Previous studies have suggested that phenolics from legume green manures may contribute to weed control through allelopathy. The objective of this study was to determine how decomposition of red clover (Trifolium pratense L.) residue affects phytotoxicity to a weed species, wild mustard (Sinapis arvensis L.). Red clover (1.25g), 30g acid washed sand, and 5ml of microbial inoculant were incubated in

Tsutomu Ohno; Kristan L Doolan

2001-01-01

405

What drives migration of riverbed sand dunes?  

NASA Astrophysics Data System (ADS)

Depending on grain size, river sediments fall into two main groups: wash load (grains that never fall out of suspension) and bed load (sediment that rests on the riverbed). Bed load sediment, similarly, can be either resting on the riverbed or temporarily in suspension, at which point it is known as suspended load.

Schultz, Colin

2014-09-01

406

Pulsed atmospheric fluidized bed combustion  

SciTech Connect

The design of the Pulsed Atmospheric Fluidized Bed Combustor (PAFBC) as described in the Quarterly Report for the period April--June, 1992 was reviewed and minor modifications were included. The most important change made was in the coal/limestone preparation and feed system. Instead of procuring pre-sized coal for testing of the PAFBC, it was decided that the installation of a milling system would permit greater flexibility in the testing with respect to size distributions and combustion characteristics in the pulse combustor and the fluid bed. Particle size separation for pulse combustor and fluid bed will be performed by an air classifier. The modified process flow diagram for the coal/limestone handling system is presented in Figure 1. The modified process flow diagrams of the fluidized bed/steam cycle and ash handling systems are presented in Figures 2 and 3, respectively.

Not Available

1992-10-01

407

Investigation into the momentum transfer between an impacting raindrop and a granular bed using 3-dimensional particle tracking  

NASA Astrophysics Data System (ADS)

The transportation of soil particles through the process of raindrop impact is a significant mechanism within the process of soil erosion. However, even though splash transport has received considerable attention over the years, little is still known about the transfer of momentum between raindrops and soil particles, with only a few recent studies investigating the fundamental interactions involved. The work presented in this study examines the interaction that occurs between an impacting water droplet and a bed of loose, graded sand, with the aim of providing further insight into the transfer of energy between them. The study focuses on quantifying the ejection of particles from the bed through momentum transfer and the resultant change in the morphology of the bed caused by the impact. The nature of the interaction that occurs between the water and the sand is defined by a large number of variables such as droplet size, impact velocity, fluid viscosity, surface tension, grain size, grain shape and packing density. However, for this study, all of these variables are kept as constant as possible, with multiple runs made of the same individual interaction, in order to examine the complexity and variability of the event. To investigate the interaction that occurs, three different techniques are used: i) High speed imaging of the interaction, looking at the dynamics of both the water and the sand ii) Three dimensional, time resolved particle tracking of the grains ejected from the sand bed during the event iii) Surface profiling of the crater produced by the impact and the large clumps of sand transported from the crater edge. The data produced demonstrates that, for example, for a 3.7-mm raindrop impacting a 150-160 µm sand bed at 6.2 m/s, only approximately 2% of the momentum of the rain drop gets transferred to the ballistic ejection of dry sand particles from the crater edge. The small amount of momentum transferred explains why the large amounts of energy present in rainstorms cause only a small proportion of total soil erosion by water processes.

Long, Edward; Hargrave, Graham; Cooper, James; Kitchener, Benjamin; Parsons, Anthony; Hewett, Caspar; Wainwright, John

2013-04-01

408

Modeling the response of shoreface-connected sand ridges to sand extraction on an inner shelf  

NASA Astrophysics Data System (ADS)

Shoreface-connected sand ridges are rhythmic bedforms that occur on many storm-dominated inner shelves. The ridges span several kilometers, are a few meters high, and they evolve on a timescale of centuries. A process-based model is used to gain a fundamental insight into the response of these ridges to extraction of sand. Different scenarios of sand extraction (depth, location, and geometry of the extraction area; multiple sand extractions) are imposed. For each scenario, the response timescale as well as the characteristics of the new equilibrium state are determined. Results show that ridges partially restore after extraction, i.e., the disturbed bathymetry recovers on decadal timescales. However, in the end, the ridge original sand volume is not recovered. Initially, most sand that accomplishes the infill of the pit originates from the area upstream of the extraction, as well as from the areas surrounding the pit. The contribution of the latter strongly decreases in the subsequent time period. Depending on the location of the pit, additional sand sources contribute: First, if the pit is located close to the downstream trough, the pit gains sand by reduction of sand transport from the ridge to this trough. Second, if the pit is located close to the adjacent outer shelf, the ridge recovery is stronger due to an import of sand from that area. Furthermore, pits that are located close to the nearshore zone have a weak recovery, deeper pits have longer recovery timescales, wide and shallow pits recover most sand, while multiple sand pits slow down the recovery process.

Nnafie, A.; de Swart, H. E.; Calvete, D.; Garnier, R.

2014-05-01

409

Precessive sand ripples in intense steady shear flows.  

PubMed

We describe experimental observations of fully developed, large-amplitude bars under the action of a shearing fluid. The experiments were performed in an annular tank filled with water and sheared above by a steady motor source. The same steady shearing flow can produce a variety of different erodible bed manifestations: advective or precessive bars, which refer to bar structures with global regularity and a near-steady precession velocity; interactive bars, the structure of which depends on local rearrangements, which are in turn a response to complex background topography; and dispersive bars, which are created when an initially isolated mound of sand evolves into a train of sand ripples. Of these, the most amenable to analysis are the precessive bars. For precession bars, we find that the skin depth, which is the nondimensionalized mean-field transport rate, grows exponentially as a function of the shear velocity. From this, we arrive at an analytical expression that approximates the precession speed of the bars as a function of shear velocity. We use this to obtain a formula for sediment transport rate. However, in intense flows, the bars can get large engendering boundary layer separation, leading to a different dynamic for bar formation and evolution. Numerical flow calculations over an experimentally obtained set of precessive bars are presented and show that classical parametrizations of mass flux in terms of bottom gradients have shortcomings. Within the range of shear rates considered, a quantity that does not change appreciably in time is the aspect ratio, which is defined as the ratio of the average bar amplitude, with respect to a mean depth, to the average bar length. PMID:21517492

Restrepo, Juan M; Moulton, Derek E; Uys, Hermann

2011-03-01

410

Bed Bugs In Wisconsin Diagnostic Lab Note  

E-print Network

Bed Bugs In Wisconsin Diagnostic Lab Note Phil Pellitteri-U.W. Insect Diagnostic Lab For most bug problems worldwide and in Wisconsin in the last 10 years. The human bed bug has become very. Human bed bugs Bed bugs are flat, oval shaped, up to 3/16 inch long, reddish- brown insects. Nymphs

Balser, Teri C.

411

Pressure Drop in a Pebble Bed Reactor  

E-print Network

Pressure drops over a packed bed of pebble bed reactor type are investigated. Measurement of porosity and pressure drop over the bed were carried out in a cylindrical packed bed facility. Air and water were used for working fluids. There are several...

Kang, Changwoo

2011-10-21

412

Petrophysical Analysis of Oil Sand in Athabasca  

NASA Astrophysics Data System (ADS)

Oil sands are the major unconventional energy sources which have great reserves in Alberta, Canada. Recovery techniques such as CSS (Cyclic Steam Stimulation) and SAGD (Steam Assisted Gravity Drainage) enabled to develop deeper bitumen about several hundred meter depth. Before applying CSS and SAGD, reservoir heterogeneity of mud barriers or shale breccias should be clarified to establish injection and production wells successfully. We conducted the integrated petro-physical analysis for oil sands deposits in Athabasca by correlating well logs with seismic data. From 33 well logs and 3D seismic, we have made P-wave impedance by recursive inversion. Target formations of our analysis were the top of Wabiskaw member. Using inverted impedance and multi-attributes, porosity volume was derived at a target depth. Porosity of time slice 375 ms ranged 20 ~ 40 % stretching porous sand body from NE to SW direction. Characteristics of porosity distribution may be useful to design optimum oil sands recovery in Athabasca.

cheong, S.; Lee, H.

2013-12-01

413

The day the sands caught fire.  

NASA Astrophysics Data System (ADS)

Not so long ago a garage-size meteorite slammed into the uninhabited heart of Arabia and flash-cooked the sand into glass. Exploration of the site is a sober reminder of the destructive power of rocks from space.

Wynn, J. C.; Shoemaker, E. M.

1998-11-01

414

Retrieval of sand density from hyperspectral BRDF  

NASA Astrophysics Data System (ADS)

In past work, we have shown that density effects in hyperspectral bi-directional reflectance function (BRDF) data are consistent in laboratory goniometer data, field goniometer measurements with the NRL Goniometer for Portable Hyperspectral Earth Reflectance (GOPHER), and airborne CASI-1500 hyperspectral imagery. Density effects in granular materials have been described in radiative transfer models and are known, for example, to influence both the overall level of reflectance as well as the size of specific characteristics such as the width of the opposition effect in the BRDF. However, in mineralogically complex sands, such as coastal sands, the relative change in reflectance with density depends on the composite nature of the sand. This paper examines the use of laboratory and field hyperspectral goniometer data and their utility for retrieving sand density from airborne hyperspectral imagery. We focus on limitations of current models to describe density effects in BRDF data acquired in the field, laboratory setting, and from airborne systems.

Bachmann, Charles M.; Abelev, Andrei; Philpot, William; Doctor, Katarina Z.; Montes, Marcos J.; Fusina, Robert; Li, Rong-Rong; van Roggen, Elena

2014-06-01

415

New developments in slow sand filtration  

SciTech Connect

Recent regulations promulgated by the U.S. Environmental Protection Agency (EPA), including the Surface Water Treatment Rule, have helped to renew the interest in the use of slow sand filtration (SSF) for treating surface waters for small communities. Slow sand filtration is not a new process, but is one that has been used to treat water effectively since the early 1800's. Interest in slow sand filtration in the United States has increased dramatically in the past thirteen years. New analytical techniques, such as particle counting, improved turbidity, improved growth media for microbiological analysis, and advanced techniques for measuring organic constituents allowed for more detailed studies than were possible in the early 1900's. The new work led to the publication of design manuals and task committee reports describing slow sand filtration in detail.

Fox, K.R.

1993-01-01

416

A Physical Taxonomy of Martian Sand and Dust Grainsat the Phoenix Landing Site  

NASA Astrophysics Data System (ADS)

A quantitative taxonomy of martian sand and dust grains for soil samples at the Phoenix lander site has been developed from the mission’s optical microscope data with a resolution of 4 ?m per pixel. Approx. 3-4000 grains were analyzed for color, hue, size, shape, surface texture, aspect ratio, and optical properties. At least 26 types of sand and dust grains have been identified. Grain colors include black, brown, orange, red, white, and clear. Most grains are opaque, but many are translucent or transparent. Grain shapes range from botryoidal, blackberry-like, bead-like and rounded, to subrounded, elongate, angular, and highly irregular forms. Surface textures range from knobbly, rough, and multifaceted to smooth and polished. Surface reflectivity varied from dull to shiny to specularly reflective. Materials may include augite, pyroxenes, olivine, volcanic glass, hematite, other iron oxides, and salts. Grain size of the sand has a modal value of ~90 ?m, but there is no gradation into dust sizes, indicating a bimodal distribution of the samples. The dust was probably imported into the region from aeolian dust storms. This accords with a mineralogical dissimilarity between the sand and dust grain populations. The sand is dominated by black and brown grains; the dust is dominated by orange grains. The Phoenix site also has centimeter and larger stones in abundance that again have no apparent gradation into the sand size material. Thus, the Phoenix landing site soil appears multimodal. The soil appears to be magnetically susceptible, but it is unclear what the source of magnetism might be. Specific magnetic minerals were not identified in the samples with the possible exception of paramagnetic microbotryoidal hematite. The soil was nevertheless adhesive to the substrates and internally cohesive (forming spherical aggregates) owing to van der Waals forces and possibly salt/moisture bonding.

Marshall, John; Stoker, Carol

2014-11-01

417

Hydrothermal deformation of granular quartz sand  

Microsoft Academic Search

Isotropic and triaxial compression experiments were performed on porous aggregates of St Peter quartz sand to explore the influence of temperature (to 225°C). During isotropic stressing, samples loaded at elevated temperature exhibit the same sigmoidal stress-strain curves and non-linear acoustic emission rates as have previously been observed from room temperature studies on sands, sandstones, and soils. However, results from our

Stephen L. Karner; Andreas K. Kronenberg; Frederick M. Chester; Judith S. Chester; Andrew Hajash Jr

2008-01-01

418

Red Flags of Abuse  

MedlinePLUS

... glasses, walker, teeth, hearing aid, medications) • Person with dementia lef t unsupervised • Person confined to bed is ... older” elders are more likely to be victimized. dementia is a significant risk factor. Mental health and ...

419

Methanogenic potential of tailings samples from oil sands extraction plants  

Microsoft Academic Search

Approximately 20% of Canada's oil supply now comes from the extraction of bitumen from the oil sands deposits in northeastern Alberta. The oil sands are strip-mined, and the bitumen is typically separated from sand and clays by an alkaline hot water extraction process. The rapidly expanding oil sands industry has millions of cubic metres of tailings for disposal and large

Phillip M. Fedorak; Debora L. Coy; Myrna J. Salloum; Marvin J. Dudas

2002-01-01

420

Treatment Efficiencies of Slow Sand Filtration for Landscape Water  

Microsoft Academic Search

The performance of the slow sand filter was examined using the landscape water with the experimental period of 46 days. The filter installed was similar to the traditional slow sand filter; expect that the top 5-cm sand was changed to the quartz sand. In this study, the variations of the turbidity, COD, BOD and TN were measured based on the

Cui Li; Yifan Wu; Liangbo Zhang; Wen Liu

2010-01-01

421

www.nasa.gov WHITE SANDS MISSILE RANGE ACCESS CAPABILITIES  

E-print Network

www.nasa.gov WHITE SANDS MISSILE RANGE ACCESS CAPABILITIES SUMMARY White Sands Test Facility (WSTF David L. Baker, NASA White Sands Test Facility, Chief, Propulsion Test Office david.l.baker@nasa.gov, (575) 524-5605 Robert E. Mitchell, NASA White Sands Test Facility, WSSH Operations Manager robert

422

Bed Sediment Grain Size Distribution and Flow Dynamics of Indianhead Reservoir, St. Croix River, MN/WI  

NASA Astrophysics Data System (ADS)

Dams alter sediment transport and flow dynamics in rivers by acting as a physical barrier to the downstream movement of bed sediment, decreasing water velocity, and allowing suspended material to settle. The St. Croix River, a National Scenic Riverway located along the border of Minnesota and Wisconsin, is subject to such alterations. Interstate Park, located several kilometers below the St. Croix Falls Dam, is host to a large population of native mussels, including threatened and endangered species. Over the past 20 years Hornbach and others (2009) have documented a ~90% decrease in the juvenile mussel population at this site, concurrent with a decrease in river bed grain size, from mixed sand/gravel to sand. One hypothesis is that the Indianhead Reservoir above the dam may be a significant source of the fine sediment found at Interstate Park as a result of extensive reservoir infilling. Changes in dam operation to run-of-river in the last decade may also drive sand transport across the dam. In this study we focus on characterizing spatial and temporal variability in hydrology and sediment transport in the Indianhead Reservoir, the impoundment behind the St. Croix Falls Dam. Our objective is to determine if the sediment at Interstate Park could originate from the river upstream of the dam. To quantify grain size distribution at the bed, measure suspended and bedload sediment in transport across a range of water discharges, and characterize flow dynamics of Indianhead Reservoir, samples were collected across a 2 km stretch of the reservoir just above the dam in 2009 and 2010. Grab samples and gravity cores of bed sediment, suspended sediment concentration (SSC) samples, vertical water velocity profiles using an Acoustic Doppler Current Profiler (ADCP), and high resolution bathymetry readings were collected at 3 points along 13 transects. Bathymetric data show depths ranging from 2-15 m, confirming significant infilling in the last 40 years. Vertical velocity profiles reveal flow velocities between 0 and 32 cm/s during the summer low flows. Bed sediments fine from coarse sand to silt and clay closer to the dam, however, reservoir cores spanning the last century reveal stochastic deposition of sand and woody debris within several hundred meters of the dam. As water discharge increases, calculated shear stresses increase, thus increasing the likelihood of sand transport. One site under moderate water discharge (8,050 cfs) exhibits basal shear stress measurements similar to fluvial systems (15 dynes/cm2). However, at low discharges (3,100 cfs) ADCP profiles show little vertical variation in water velocity. During spring or flood stages (~25,000 cfs), the larger shear stresses would allow the sand grain size fraction to likely reach and breach the dam. Results demonstrate sand is present in the reservoir close to the dam. Calculations of settling velocities for available bed sediment, and estimates of residence time for water in the reservoir will further illuminate our understanding of sand transport behind the dam. Additional electron microscopy to compare reservoir and Interstate Park bed sediment will improve our understanding of possible sediment transport from the reservoir to mussel beds downstream.

Jackson, K. J.; MacGregor, K. R.; Hornbach, D. J.

2010-12-01

423

Red Harvester Ants  

E-print Network

. ? Horned lizards normally inhabit flat, open, dry country with little cover. Urbanization, mowing, shredding, shallow discing and other land use practices can eliminate or reduce the production of weed seeds on which harvester ants feed. Harvester ants... Entomologist, The Texas A&M University System. Red harvester ants Food sources Red harvester ant foragers collect seeds and dead insects and store them in the nests as food for the colony. The ants? mouthparts are designed for chewing. Management Red...

Drees, Bastiaan M.

2006-04-24

424

Tidal sands as biogeochemical reactors  

NASA Astrophysics Data System (ADS)

Sandy sediments of continental shelves and most beaches are often thought of as geochemical deserts because they are usually poor in organic matter and other reactive substances. The present study focuses on analyses of dissolved biogenic compounds of surface seawater and pore waters of Aquitanian coastal beach sediments. To quantitatively assess the biogeochemical reactions, we collected pore waters at low tide on tidal cross-shore transects unaffected by freshwater inputs. We recorded temperature, salinity, oxygen saturation state, and nutrient concentrations. These parameters were compared to the values recorded in the seawater entering the interstitial environment during floods. Cross-shore topography and position of piezometric level at low tide were obtained from kinematics GPS records. Residence time of pore waters was estimated by a tracer approach, using dissolved silica concentration and kinetics estimate of quartz dissolution with seawater. Kinetics parameters were based on dissolved silica concentration monitoring during 20-day incubations of sediment with seawater. We found that seawater that entered the sediment during flood tides remained up to seven tidal cycles within the interstitial environment. Oxygen saturation of seawater was close to 100%, whereas it was as low as 80% in pore waters. Concentrations of dissolved nutrients were higher in pore waters than in seawater. These results suggest that aerobic respiration occurred in the sands. We propose that mineralised organic matter originated from planktonic material that infiltrated the sediment with water during flood tides. Therefore, the sandy tidal sediment of the Aquitanian coast is a biogeochemical reactor that promotes or accelerates remineralisation of coastal pelagic primary production. Mass balance calculations suggest that this single process supplies about 37 kmol of nitrate and 1.9 kmol of dissolved inorganic phosphorus (DIP) to the 250-km long Aquitanian coast during each semi-diurnal tidal cycle. It represents about 1.5% of nitrate and 5% of DIP supplied by the nearest estuary.

Anschutz, Pierre; Smith, Thomas; Mouret, Aurélia; Deborde, Jonathan; Bujan, Stéphane; Poirier, Dominique; Lecroart, Pascal

2009-08-01

425

Layers, Landslides, and Sand Dunes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 27 October 2003

This image shows the northern rim of one of the Valles Marineris canyons. Careful inspection shows many interesting features here. Note that the spurs and gullies in the canyon wall disappear some distance below the top of the canyon wall, indicating the presence of some smooth material here that weathers differently from the underlying rocks. On the floor of the canyon, there are remains from a landslide that came hurtling down the canyon wall between two spurs. Riding over the topography of the canyon floor are many large sand dunes, migrating generally from the lower right to upper left.

Image information: VIS instrument. Latitude -14.1, Longitude 306.7 East (53.3 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

426

Evaluating Sand Transport Through Two Spillway Diversions on the Lower Mississippi River During the Flood of 2011: Implications for Land Management Via Controlled Diversions  

NASA Astrophysics Data System (ADS)

The Mississippi River flood of 2011 necessitated operation of both the Bonnet Carré and Morganza spillways, so that up to 25% of the lower river-water discharge plus associated sediment was diverted into Lake Pontchartrain and Atchafalaya River basin, respectively. The design of each spillway is quite different, and here we present data used to analyze the sand transport capacity of both structures. The Morganza Floodway is set several kilometers from a Mississippi River bend reach, is buffered by a wooded floodplain and has a long, contained forebay. This site location and design inhibits movement of sand from the river through the spillway. In contrast, the Bonnet Carré Spillway is positioned adjacent to the river channel and just downstream of two bend reaches; enhanced secondary flow and turbulence associated with this planform contributes to sand suspension, promoting extensive sediment transport through the spillway. Interestingly, despite the depth of the weir separating the Mississippi River channel and the Bonnet Carré Spillway (approximately the upper 10% of the thalweg depth), the spillway captured a significant proportion of channel-bed sand, based on our data for grain-size distribution of sand on the river-channel bed compared to deposits in the spillway. These results indicate that planform controls and sediment transport dynamics can be used to predict the optimal placement of diversion structures intended to distribute water and sediment from the lower Mississippi River to surrounding wetlands, thereby helping prevent coastal erosion and degradation of infrastructure.

Czapiga, M. J.; Nittrouer, J. A.; Brantley, C.; Cash, R. W.; Parker, G.; Best, J. L.

2011-12-01

427

Bed forms created by simulated waves and currents in a large flume  

USGS Publications Warehouse

The morphology and evolution of bed forms created by combinations of waves and currents were investigated using an oscillating plate in a 4-m-wide flume. Current speed ranged from 0 to 30 cm/s, maximum oscillatory velocity ranged from 20 to 48 cm/s, oscillation period was 8 s (except for one run with 12 s period), and the median grain size was 0.27 mm. The angle between oscillations and current was 90°, 60°, or 45°. At the end of each run the sand bed was photographed and ripple dimensions were measured. Ripple wavelength was also determined from sonar images collected throughout the runs. Increasing the ratio of current to wave (i.e., oscillatory) velocity decreased ripple height and wavelength, in part because of the increased fluid excursion during the wave period. Increasing the ratio of current to waves, or decreasing the angle between current and waves, increased the three-dimensionality of bed forms. During the runs, ripple wavelength increased by a factor of about 2. The average number of wave periods for evolution of ripple wavelength to 90% of its final value was 184 for two-dimensional ripples starting from a flat bed. Bed form orientations at the end of each run were compared to four potential controlling factors: the directions of waves, current, maximum instantaneous bed shear stress, and maximum gross bed form normal transport (MGBNT). The directions of waves and of MGBNT were equally good predictors of bed form orientations, and were significantly better than the other two factors.

Lacy, Jessica R.; Rubin, David M.; Ikeda, Hiroshi; Mokudai, Kuniyasu; Hanes, Daniel M.

2007-01-01

428

Quantifying Stream Bed Gravel Mobility from Friction Angle Measurements  

NASA Astrophysics Data System (ADS)

A method to measure friction angles using force gauges was field tested to determine its utility at quantifying critical shear stress in a gravel bedded reach of the San Joaquin River in California. Predictions of mobility from friction angles were compared with observations of the movement of tagged particles from locations for which local shear stress was quantified with a validated 2-D flow model. The observations of movement, distance of travel, and location of the end of travel were made after extended flow releases from Friant dam. Determining the critical shear stress for gravel bed material transport currently depends upon bedload sampling or tracer studies. Often, such measurements can only be made during occasional and untimely flow events, and at limited, suboptimal locations. Yet, theoretical studies conclude that the friction angle is an important control on the critical shear stress for mobility of any grain size, and therefore of the excess shear stress which strongly influences bedload transport rate. The ability to predict bed mobility at ungauged and unmonitored locations is also an important requirement for planning of flow regimes and channel design. Therefore, a method to measure friction angles that can be performed quickly in low flow conditions would prove useful for river management and research. To investigate this promising method friction angle surveys were performed at two riffle sites where differences in bed material size and distribution, and channel slope were observed. The friction angle surveys are sensitive enough to detect differences between the sites as well as spatially and temporally within a single riffle. Low friction angles were observed along the inside of a long bend where sand content was greater (by ~20%) than other surveyed locations. Friction angles decreased slightly after a depositional event associated with transient large woody debris and bank erosion, and increased again after a 5 year return interval flow reorganized the sediment. The shear stress capable of mobilizing bed material at the sites was also determined from monitored RFID tagged tracer gravel-cobbles and computed from a 2-D hydraulic model. These computed bed mobilizing shear stresses are compared with those predicted from observations and measurements made during the force gauge surveys thereby demonstrating their capability to quantify the critical shear stress and the applicability of the method.

Meyers, M. A.; Dunne, T.

2012-12-01

429

Hyporheic and Total Transient Storage in Small Sand-Bed Streams  

Technology Transfer Automated Retrieval System (TEKTRAN)

Key processes in stream ecosystems are linked to hydraulic retention, which is the departure of stream flow from ideal “plug flow,” and reflects fluid movement through surface and hyporheic storage zones. Most existing information about hyporheic exchange is based on flume studies or field measureme...

430

Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass  

NASA Astrophysics Data System (ADS)

This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions. A variety of experimental techniques are employed to study the behavior of two constituting phases of a fluidized bed, i.e., dilute (bubble) and dense (emulsion) phases. Exploring the characteristic fluidization velocities of sand-biomass mixtures unveils that the onset of bubbling in these systems occurs at a higher gas velocity compared to that of the initial fluidization velocity (Uif). The initial bubbling velocity (Uib), the final fluidization velocity ( Uff), and the transition gas velocity from bubbling to turbulent regime (Uc) rise by increasing the fraction of biomass in the mixture. Statistical analysis of the pressure signal at top of the bed reveals that increasing the biomass load hinders the evolution of bubbles at a low gas velocity (U<0.6 m/s), while at high velocities, the bubbling trend of beds containing different fractions of biomass is comparable. The addition of biomass particles to a bed of sand leads to an increase in the mean voidage of the bed; however, the voidage of each phase remains unaffected. It is observed that large biomass particles trigger a break-up of the bubbles, which results in boosting bubbling frequency. The fraction of bubbles at the center of the bed increases with the load of biomass. At the wall region, however, it starts to decrease by adding 2% wt. biomass to pure sand and then increases with the further addition of biomass. The Radioactive Particle Tracking (RPT) technique is implemented in the second section of this work to study the motion and distribution of biomass particles at U=0.36 m/s and U=0.64 m/s. In this regard, an active biomass particle is tracked for a long period of time and its instantaneous position is recorded. The acquired data is then processed to achieve the time-averaged concentration profile of biomass particles. This profile represents the segregation of biomass particles, which tend to accumulate in the upper levels of the bed. Changes in the fraction of biomass with increasing gas velocity are inferred from the local changes of the time-averaged pressure drop values at the top of the bed. To determine the parameters affecting the movement and segregation of biomass particles, their circulatory motion is also scrutinized using the RPT data. The circulation of biomass is impeded when the load of biomass rises at U=0.36 m/s, resulting in a more pronounced segregation of sand and biomass. The opposite trend is observed at U=0.64 m/s. This prompts a more uniform distribution of particles along the bed and brings about a higher degree of mixing. The average rise velocity of biomass is 0.2 times the bubble velocity, regardless of the biomass load or fluidization velocity. A one-dimensional model is proposed to predict the volume fraction of biomass along the bed. Some of the terms of this model are linked to the fluidizing behavior of biomass particles as deduced from the RPT findings. The fluidization of sand and cylindrical biomass particles is also simulated using the BARRACUDA CPFD software, which is based on the Lagrangian-Eulerian approach. Simulation and experimental results are compared in order to evaluate the capability of the numerical approach to predict the bubbling characteristics of the sand-biomass mixture for systems differing in composition and fluidization velocity. The last part of this thesis is devoted to the separation of the main components of the shredded bulky waste. A step-wise process has been developed based on the elutriation and density segregation techniques. After removal of the light and interwoven species of the shredded waste by elutriation, the nonelutri

Fotovat, Farzam

431

South America and a Few Grains of Sand. Part 1: Beach Sands.  

ERIC Educational Resources Information Center

Continental geology and tectonics are explored through this study of modern beach sands of South America. This report assesses how well petrographic studies of sandstones can recreate continental geography. D