Note: This page contains sample records for the topic red sand beds from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Fluidized bed retorting of tar sands  

Microsoft Academic Search

Raw tar sand is treated in a fluidized bed reactor means wherein the raw tar sands are fed into an area below the top of the bed. The bitumen is converted in the process in a reducing atmosphere including steam to produce hot coked sand and hot off-gases. Off-gases from the reactor means pass through a heat exchanger means to

P. H. II

1978-01-01

2

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

USGS Publications Warehouse

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

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

2007-01-01

3

MODELING LARGE WOOD STRUCTURES IN SAND BED STREAMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

In-stream large wood structures (LWS) are becoming increasingly popular throughout the world. The LWS improve aquatic habitat quality and protect banks from erosion. While most reports describe the LWS in the Northwest as successful, LWS in one Mississippi sand-bed stream had an unacceptable failure...

4

Sand Bed Morphodynamics under Standing Waves and Vegetated Conditions  

NASA Astrophysics Data System (ADS)

Littoral processes such as sediment transport, wave attenuation, and boundary layer development are governed by the presence of bathymetric features, which include large-scale sand bars upon which smaller-scale sand ripples are superimposed, as well as the presence of submarine vegetation. Numerous studies on sand ripples and bars have aided to elucidate the dynamics in oscillatory flows; however, the effect of vegetation on the system is less understood. Recent laboratory studies have focused on quantifying wave attenuation by emergent vegetation as a natural method to mitigate storm surges. The emergent vegetation, while promising for coastal protection, alters sediment transport rates directly by the physical presence of the plants near the bed and indirectly from reduction in near-bed shear stresses due to attenuated wave energy. The experimental work herein focuses on the area near the deeply submerged vegetated canopy limit (current work has a ratio of mean still water depth to plant height, H/h, = 7.9) to minimize the effect on the surface waves and discern the direct impact vegetation has on sand bed morphodynamics. Experiments were conducted in the large wave tank (49-m long by 1.83-m wide by 1.22-m deep) in the Ven Te Chow Hydrosystems Laboratory at the University of Illinois in which a high reflection wave forcing was used over a uniform sand bed with a 0.25-mm median sediment diameter in which staggered and uniform arrangements of idealized vegetation (i.e., 6.35-mm diameter rigid wooden cylinders) were positioned along the bed (e.g., at predetermined sand bar troughs and over an entire sand bar). The resulting bathymetric evolution from the vegetated case experiments were compared to the base case of no vegetation using two optical methods: a high-resolution laser displacement sensor for three-dimensional surveys and digitized profiles via high-definition panoramic images of the entire test section. The experimental findings illustrate the profound effect that vegetation can impose on bed form evolution whereby the rate of development can be significantly reduced, mitigated, or even completely redirected. These findings suggest that bottom roughness could be controlled with the help of vegetation thus providing a means to reduce wave energy and prevent sediment erosion. Three-dimensional bathymetric scan of a sand bar having superimposed ripples with idealized vegetation (i.e., 6.35-mm diameter rigid wooden cylinders) positioned at the bar toughs.

Landry, B. J.; Garcia, M. H.

2010-12-01

5

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

6

Comparison of macrofaunal invertebrates in sand dollar ( Dendraster excentricus ) beds and in adjacent areas free of sand dollars  

Microsoft Academic Search

Abundances of macroinfaunal invertebrates in sand dollar (Dendraster excentricus) beds and in adjacent areas free of sand dollars were studied at 10 intertidal sites in the Pacific Northwest region of the USA and Canada. Each site was sampled once in late summer of 1977. There were no significant differences in overall diversity of species between the beds and adjacent areas;

A. L. Smith

1981-01-01

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

Observed and predicted bed forms and their effect on suspended sand concentrations  

Microsoft Academic Search

In this paper, we study the effect of bed forms on suspended sand concentrations and we compare three existing bed form predictors to field and laboratory measurements over a wide range of conditions and propose a new predictor that better collapses the measured bed form dimensions. We apply the different bed form predictors to estimate the suspended sediment concentration distributions

B. T. Grasmeijer; M. G. Kleinhans

2004-01-01

9

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

Microsoft Academic Search

Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profilers (ADCPs) has emerged as a promising approach for evaluating bed load transport. However, a better understanding of how ADCP data relate

David Gaeuman; Robert B. Jacobson

2006-01-01

10

Applicability of clean technology of conical spouted bed for thermal remediation of sand polluted by oil spill  

Microsoft Academic Search

A conical spouted bed combustor that operates from the spouted bed regime to dilute spouted bed regime (jet spouted bed) has been used in the thermal remediation of sand from Arminza beach polluted with oil from Prestige spill. Experimental study on operation in a pilot plant combustor has been carried out with beds consisting of sand with different water weight

M. J. San Jose; S. Alvarez; L. B. Lopez; I. Garcia

2011-01-01

11

Phosphorus removal by sands for use as media in subsurface flow constructed reed beds  

Microsoft Academic Search

Sorption of P to the bed sand medium is a major removal mechanism for P in subsurface flow constructed reed beds. Selecting a sand medium with a high P-sorption capacity is therefore important to obtain a sustained P-removal. The objective of this study was to evaluate the P-removal capacities of 13 Danish sands and to relate the removal to their

C. A. ARIAS; M. DEL BUBBA; H. BRIX

2001-01-01

12

Numerical simulation of saltating particles in atmospheric boundary layer over flat bed and sand ripples  

NASA Astrophysics Data System (ADS)

In this work, we numerically simulated the saltating particles in a turbulent boundary layer over flat bed and sand ripples. By using natural sand grains in a wind tunnel, we obtained the initial conditions for the simulation and also verified the correctness of the numerical model. We carefully analyzed the numerically simulated saltating particle movement over the two sand beds, and we found the following. (1) The aeolian sand transport is a dynamic equilibrium process on both sand beds, and it took longer to reach equilibration on the sand ripples than on the flat bed. (2) According to the mass flux profile at the trough of the sand ripples, there is a maximum mass flux at about 4 cm height in the leeward section. The mass flux increases with height below 4 cm and decreases with height above 4 cm. (3) The wind profile near the surface is modified by saltating particles on the two different sand beds, and the flow field characteristics of the sand ripples are more complex than that of the flat bed.

Tong, Ding; Huang, Ning

2012-08-01

13

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

USGS Publications Warehouse

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

Wright, S.; Parker, G.

2004-01-01

14

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

15

Coal bed methane potential of the Sand Wash Basin, Green River coal region, Colorado  

Microsoft Academic Search

The Sand Wash Basin covers most of the Colorado portion of the Green River coal region. Significant coal beds are found in four Cretaceous formations in the basin: the Iles and Williams Fork Formations of the Mesaverde Group, the Lance Formation, and the Fort Union Formation. Individual coal beds can reach thicknesses of 36 ft in the Mesaverde, 13 ft

D. L. Boreck; C. M. Tremain; L. Sitowitz; T. D. Lorenson

1981-01-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

17

Deposition of carbonate mud beds within high-energy subtidal sand Dunes, Bahamas  

SciTech Connect

Laminated, carbonate mud beds are being deposited in the interisland channels of the Exuma Cays in the Bahamas. They are associated with stromatolites and interbedded with ooid sands that form large migrating subtidal dunes on flood tidal deltas and bars. Currents up to 3 knots sweep in and out of the 4-8 m deep channels 3 hours out of every 6 hours, creating a high-energy bank margin environment not usually considered to be the site of mud-sized particle deposition. Mud deposits reach thicknesses of 1 m and have individual beds 2-5 cm thick. When exposed to flowing seawater, bed surfaces become encrusted with carbonate cement and algal mats. The white interior of mud beds between the crusts appears homogeneous, is soft, and has the consistency of ''tooth paste.'' Loose uncemented ooid sand is found above and below the mud beds, showing that both are occupying the same depositional environment. Rip-up clasts of the crusted mud beds, formed by scour of underlying sands, are carried throughout the channels and accumulate as a lag deposit within the troughs of migrating dunes. Some clasts are colonized by algal mats that trap ooid and skeletal sands forming stromatolite structures that can grow up to 2 m high.

Dill, R.F.; Steinen, R.P.

1988-01-01

18

Inclination Error Correction In Red Beds: Is It Possible ?  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

19

Nickel removal from nickel plating waste water using a biologically active moving-bed sand filter  

Microsoft Academic Search

Efficient removal of dissolved nickel was observed in a biologically active moving-bed `MERESAFIN' sand filter treating rinsing water from an electroless nickel plating plant. Although nickel is fully soluble in this waste water, its passage through the sand filter promoted rapid removal of approximately 1 mg Ni\\/l. The speciation of Ni in the waste water was modelled; the most probable precipitates

Thomas Pümpel; Lynne E. Macaskie; John A. Finlay; Ludo Diels; Marios Tsezos

2003-01-01

20

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

21

General Suppression of Escherichia coli O157:H7 in Sand-Based Dairy Livestock Bedding? †  

PubMed Central

Sand bedding material is frequently used in dairy operations to reduce the occurrence of mastitis and enhance cow comfort. One objective of this work was to determine if sand-based bedding also supported the microbiologically based suppression of an introduced bacterial pathogen. Bedding samples were collected in summer, fall, and winter from various locations within a dairy operation and tested for their ability to suppress introduced populations of Escherichia coli O157:H7. All sources of bedding displayed a heat-sensitive suppressiveness to the pathogen. Differences in suppressiveness were also noted between different samples at room temperature. At just 1 day postinoculation (dpi), the recycled sand bedding catalyzed up to a 1,000-fold reduction in E. coli counts, typically 10-fold greater than the reduction achieved with other substrates, depending on the sampling date. All bedding substrates were able to reduce E. coli populations by over 10,000-fold within 7 to 15 dpi, regardless of sampling date. Terminal restriction fragment length polymorphism (T-RFLP) analysis was used to identify bacterial populations potentially associated with the noted suppression of E. coli O157:H7 in sand bedding. Eleven terminal restriction fragments (TRFs) were overrepresented in paired comparisons of suppressive and nonsuppressive specimens at multiple sampling points, indicating that they may represent environmentally stable populations of pathogen-suppressing bacteria. Cloning and sequencing of these TRFs indicated that they represent a diverse subset of bacteria, belonging to the Cytophaga-Flexibacter-Bacteroidetes, Gammaproteobacteria, and Firmicutes, only a few of which have previously been identified in livestock manure. Such data indicate that microbial suppression may be harnessed to develop new options for mitigating the risk and dispersal of zoonotic bacterial pathogens on dairy farms.

Westphal, Andreas; Williams, Michele L.; Baysal-Gurel, Fulya; LeJeune, Jeffrey T.; McSpadden Gardener, Brian B.

2011-01-01

22

Adsorption of organics from tar sand water by activated carbon in packed beds. Final report  

SciTech Connect

The adsorption of TS-1S and TS-2C tar sand waters were studied at 278 and 298/sup 0/K on activated carbon in both batch and packed bed experiments. The isotherms were nonlinear over the entire liquid concentration ranges. Breakthrough curves were obtained in packed bed experiments as a function of bed lengths, particle size, and liquid velocity. A mechanistic approach was used to solve the mass transfer equations for the packed adsorber, the mass transfer coefficients and the rates of adsorption were calculated. Also the breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.

Hines, A.L.; Pedram, E.O.

1982-12-30

23

RESPONSE OF FISHES AND AQUATIC HABITATS TO SAND-BED STREAM RESTORATION USING LARGE WOODY DEBRIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Large woody debris structures hold promise as cost-effective stream corridor rehabilitation measures. Pre- and post construction data are presented that describe effects of habitat rehabilitation of Little Topashaw Creek, a sinuous, fourth-order sand-bed stream draining 37 km2 in northwest Mississip...

24

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

NASA Astrophysics Data System (ADS)

The factors controlling the complex interaction of a coarse streambed with flow and sediment are difficult to measure. However, planning for reservoir flushing or dam removal requires knowledge of these interactions. In both cases, impounded sediments are introduced to channel beds that have had fine sediment particles removed without replacement. The channel bed pore space interacts with the flow and provides storage for particles. In order to address the need for information on such systems, an adjustable-slope, recirculating laboratory flume was used to study the changes in flow and turbulence caused by sand added to an immobile gravel bed. Detailed measurements were made using an acoustic Doppler velocimeter that collected three velocity components at a rate of 200 Hz. Because of the rough nature of the bed, individual velocity profiles varied significantly; therefore, in order to determine general trends, the data were spatially averaged over six 10 × 20 cm planes parallel to the bed with the lowest plane about 2 cm below the maximum gravel elevation. The increasing elevation of sand relative to the gravel layer resulted in decreased bed shear stress, decreased Reynolds stress, increased relative turbulence intensity, and a near-bed shift toward sweep-dominated turbulence.

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

2011-03-01

25

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

Microsoft Academic Search

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.

Yantao Cui

2007-01-01

26

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

USGS Publications Warehouse

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

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

2000-01-01

27

Development of an inclined liquid fluidized bed for tar sand processing  

SciTech Connect

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

Johnson, L.A. Jr.

1989-12-01

28

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

29

Relationship of Fish Mesohabitat to Flow in a Sand-Bed Southwestern River  

Microsoft Academic Search

We quantified the availability and utilization of habitat types by eight small-bodied cyprinid fish species, including the federally threatened Pecos bluntnose shiner Notropis simus pecosensis, in the Pecos River, New Mexico. The Pecos River is a medium-sized, sand-bed river with a highly variable hydrograph and some reaches characterized by historic and recent periods of flow intermittency. Fish habitat was described

Jon W. Kehmeier; Richard A. Valdez; C. Nicolas Medley; Orrin B. Myers

2007-01-01

30

Co-pyrolysis of walnut shell and tar sand in a fixed-bed reactor  

Microsoft Academic Search

This study investigated potential synergistic activities between tar sand and walnut shell during co-pyrolysis. A series of pyrolysis studies were conducted under specific operating conditions in a fixed-bed reactor. The highest yield of bio-oil from the co-pyrolysis was 31.84wt.%, which represented an increase of 7.88wt.% compared to the bio-oil yield from the pyrolysis of walnut shell alone. The bio-oils were

Yakup Kar

2011-01-01

31

Chemical remanent magnetization of red beds and synthetic hematite  

SciTech Connect

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

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

1991-03-01

32

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

33

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

34

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

35

The measurement of the rate of burning of different coal chars in an electrically heated fluidised bed of sand  

Microsoft Academic Search

This work measured the rates of burning of three coal chars. This was done by adding small batches (?3mg; particle size 106–150?m) of a char to a hot bed of silica sand (diam. 90–126?m) fluidised by different mixtures of O2+N2, varying from 0 to 100vol% O2. The bed was electrically heated and maintained at 700, 800, 900 or 950?C. The

P. S. Fennell; S. Kadchha; H.-Y. Lee; J. S. Dennis; A. N. Hayhurst

2007-01-01

36

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

37

Preliminary Study of Paleomagnetism of Some Mesozoic and Cenozoic Red Beds of South China.  

National Technical Information Service (NTIS)

The paper presents data on the paleomagnetic pole position for the Mesozoic and Tertiary, derived from red beds in Xichuan, Yunnan, Hunan, Hubei and Guangdong Provinces. The results obtained by analysis and by comparison with those found from neighbouring...

L. Hauan-ti L. Hwa-me L. Haishan L. Chun Y. Shu-juan

1966-01-01

38

Co-pyrolysis of walnut shell and tar sand in a fixed-bed reactor.  

PubMed

This study investigated potential synergistic activities between tar sand and walnut shell during co-pyrolysis. A series of pyrolysis studies were conducted under specific operating conditions in a fixed-bed reactor. The highest yield of bio-oil from the co-pyrolysis was 31.84 wt.%, which represented an increase of 7.88 wt.% compared to the bio-oil yield from the pyrolysis of walnut shell alone. The bio-oils were characterized using various spectroscopic and chromatographic analysis techniques. The results indicated that the synergetic effect increased the co-pyrolysis bio-oil yield and its quality. Consequently, the results indicate that the bio-oils obtained will be suitable for the production of fuels and chemicals as feedstock after required improvements. PMID:21875795

Kar, Yakup

2011-08-10

39

Sand  

NSDL National Science Digital Library

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

40

Statistical behaviors of different-sized grains lifting off in stochastic collisions between mixed sand grains and the bed in aeolian saltation  

Microsoft Academic Search

Multiple-size splash models are derived from the simulation results of mixed grain-bed impact process of windblown sand flow based on the Particles Dynamics Method (PDM) and parallel algorithm. Unlike previous studies, a probability density distribution of sand diameter is considered in the present study, in which a two-dimensional mixed sand bed is generated by a random method. After the diameter

Wan-Qing Li; You-He Zhou

2007-01-01

41

A parametric study on the factors affecting the froth floatation of Jordanian tar sand utilizing a fluidized bed floatator  

Microsoft Academic Search

Different parameters affecting the behavior of froth flotation of Jordanian tar sand, obtained from the Dead Sea area, were studied. This study was performed in a modified fluidized bed floatator. The effects of the addition of a flotation agent, NaOH, temperature and flotation time on the beneficiation of bitumen in the froth were investigated. It was found that the beneficiation

Awni Al-Otoom; Mamdouh Allawzi; Adnan M. Al-Harahsheh; Mohammad Al-Harahsheh; Randa Al-Ghbari; Raeda Al-Ghazo; Husam Al-Saifi

2009-01-01

42

A paleomagnetic study of remagnetized Upper Jurassic red beds from Chihuahua, northern Mexico  

Microsoft Academic Search

Paleomagnetic results from 75 samples (132 specimens) collected from 20 beds from a ~55-m thick sequence of Upper Jurassic red beds from La Casita Formation, northern Mexico are reported. Detailed partial thermal (up to 680°C) and alternating field (up to 320 mT) demagnetizations reveal different behaviors of vectorial composition and magnetic stability. Before tilt correction, the directions cluster around the

Emilio Herrero-Bervera; Jaime Urrutia-Fucugauchi; M. A. Khan

1990-01-01

43

Modeling approach to phenol oxidation by a sand-based packed-bed electrode system (SPBEs).  

PubMed

A comparative study of phenol oxidation using pure electrolysis (PEs) and sand-based packed-bed electrode systems (SPBEs) was performed under conditions of phenol concentration 800 mg L(-1), initial pH 6.5, current density 100 A m(-2) and sodium sulfate (Na(2)SO(4)) 3.0% (w/w) on IrO(2)-Ta(2)O(5)/Ti anode. The results show quartz sand, a non-conducting material is incapable of expanding the electrode area and the phenol oxidation in SPBEs commences only at the electrode surface. From the theoretical description of the mass transport coefficient and chemical oxygen demand (COD), we confirm that the enhancement of the COD removal efficiency, current and space-time yields in SPBEs is due to the improvement of mass transport properties. The proposed SPBEs shows superiority to the PEs on saving energy at the same applied voltage, however, when operated under the same applied current density the energy consumption of the former would be much higher than that of the latter because of the rise of the applied cell voltage. PMID:22699349

Wang, Lizhang; Li, Peng; Yan, Qian

2012-01-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

45

Sedimentation and petrology of Fanshawe sand, Red Oak field, Arkoma basin, Oklahoma  

SciTech Connect

The Fanshawe sand, a very fine to fine-grained lithic sandstone, probably formed in moderate to deep water downslope from a delta system to the east. Sediment-laden discharge flowed from east to west as channelized, bottom-hugging density currents. Deposition of the Fanshawe sand seems to have been restricted to a west-southwest-trending zone approximately 2 mi wide on the north side of Red Oak field. The sand is a composite of a series of narrow, shifting, meandering submarine channels that often are stacked. Stratigraphic cross sections show extreme variability, even along depositional strike, and individual channels typically are narrower than the distance between development wells. Reservoir quality is enhanced where these narrow channels coalesce horizontally and vertically. Net sand thickness ranges from 36 to 180 ft with associated reserves of up to 14 bcf/well. Completion rates can reach 8 mmcf/day with decline rates averaging 6%. Preliminary results of an increased density drilling program further substantiate the narrow, sinuous nature of these fan channels. Air drilling causes severe hole washouts, making net pay determinations questionable. But by mapping overall net sand trends, it is possible to high-grade drilling prospects. Prediction of porosity development, however, remains difficult. Porosity in the Fanshawe is due to (1) precipitation of pore-lining chlorite, which retarded quartz cementation by blocking potential nucleation sites on detrital quartz grains and preserved primary porosity, and (2) dissolution of feldspars and lithic fragments. The better reservoir rock has both porosity types. Where pore-lining chlorite was absent, thin, or discontinuous, quartz overgrowths developed and intergranular porosity decreased. This created a pore geometry consisting of poorly interconnected, disseminated, intragranular/moldic, dissolution pores and low permeability.

Pittman, E.D.; Wray, L.L. (Amoco Production Co., Tulsa, OK (USA))

1989-08-01

46

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.

Schleicher, Annie; Extra, Public B.

47

[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

48

Simulation on sand grain\\/bed collision mechanism: Cascade collision and ejection (1)  

Microsoft Academic Search

Ejection of sand grains from a sand surface is assumed to result from cascade collision caused by the impact of a saltating particle. Allowing for only two-body cascade collision and introducing new quantities such as the cross-section for sand grain–grain collisions and sand surface binding energy, the theoretical model for the cascade collision of ion particles is applied to simulate

Wanquan Ta; Zhibao Dong

2007-01-01

49

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

Microsoft Academic Search

Oil imports could be reduced and domestic gas production increased if additional gas production is obtained from four unconventional resources-eastern Devonian shales, tight sands, coal beds, and geopressured zones. Gas produced from these resources can help maintain overall production levels as supplies from conventional gas sources gradually decline. The eastern shales and western sands are the chief potential contributors in

Staats

1980-01-01

50

Secular variation during the Permian Superchron: a comparison between red bed and volcanic records  

NASA Astrophysics Data System (ADS)

Geodynamo models predict reduced secular variation during a Superchron, a long period during which the geomagnetic field shows no reversals. Our earlier research, however, showed that Permian Superchron red beds appeared to record secular variation similar to that of the recent field. Here, we have extended our sedimentary record to Permian red beds from the Lodeve (France). In addition, we have carried out a detailed paleomagnetic study of the volcanics in the Oslo graben, a Permian Superchron lava province containing a long sequence of Carboniferous to Permian volcanics and sediments (Olaussen et al 1994; Sundvoll et al 1990). For this study, a large number of lava flows were sampled from the Krokskogen and Vestfold lava plateaus, and from the Brumundall area. Interestingly, the latter area contains also red beds intercalated in the lava sequence. NRM (normal remanent magnetisation) directions were determined by stepwise thermal demagnetization. We compare the distributions of NRM directions of both lithologies, and we test the distributions using the geomagnetic field model TK03.GAD (Tauxe and Kent, 2004). In addition, we carried out extensive rock magnetic experiments, including thermomagnetic runs, acquisition of isothermal remanent magnetisation and hysteresis curves measurements. These experiments show that the magnetic carriers in the Oslo graben volcanics are both magnetite and hematite, while in the red beds there is considerable variation in the type of remanence carrier.

Haldan, M. M.; Langereis, C. G.; Larsen, B. T.; Heyer, H. J.

2006-12-01

51

Contrasting red bed diagenesis: the southern and northern margin of the Central European Basin  

NASA Astrophysics Data System (ADS)

We compare the diagenetic evolution of deeply buried Rotliegend (Permian) red bed sandstones at the southern and northern margin of the Central European Basin (CEB) in Germany. Main target is to evaluate the influence of maturation products from hydrocarbon (HC) source rocks during red bed diagenesis. At the southern margin of the CEB, thick coal-bearing Carboniferous source rocks are omnipresent beneath the Rotliegend. They contain dominantly gas-prone terrigenous organic material and some oil source rocks. Hydrocarbons were generated from Late Carboniferous onwards throughout most of basin subsidence. At the northern margin of the CEB, source rocks are almost absent due to deep erosion of Carboniferous rocks and a low TOC of local Lower Carboniferous relics. Early diagenetic processes are comparable at both basin margins. Significant differences in burial diagenetic evolution are spatially correlated to the occurrence of hydrocarbon source rocks. Burial diagenesis at the southern margin of the CEB is characterized especially by bleaching of red beds, major dissolution events, pervasive illite formation, impregnation of pore surfaces with bitumen, and formation of late Fe-rich cements. Almost none of these features were detected at the northern basin margin. Instead, relatively early cements are preserved down to maximum burial depths. This suggests that major diagenetic mineral reactions in deeply buried red bed sandstones are controlled by the presence or absence of maturing hydrocarbon source rocks.

Schöner, Robert; Gaupp, Reinhard

2005-12-01

52

Depositional environments, paleomagnetism, and tectonic significance of Huizachal red beds (lower Mesozoic), northeastern Mexico  

Microsoft Academic Search

The Huizachal Group (Triassic to Middle Jurassic) exposed in northeastern Mexico is made up of La Boca and La Joya Formations in the eastern part of the study area, and the Nazas Formation to the west. The Huizachal sediments were deposited as alluvial fans prograding outward from high-standing horst blocks into actively subsiding grabens. These red beds are composed of

Belcher

1979-01-01

53

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

54

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

55

BED FORMS IN BIMODAL SAND-GRAVEL SEDIMENTS: LABORATORY AND FIELD ANALYSIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bed forms were studied in Goodwin Creek and a laboratory flume channel. The bed sediment had median diameters of 8.3 and 1.82 mm, respectively and both had bimodal size distributions. Cluster analysis was used to identify three groupings of bed forms from the laboratory flume experiments. For the...

56

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

PubMed Central

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

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

2011-01-01

57

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

PubMed

Permeable sediments and associated microbial communities play a fundamental role in nutrient recycling within coral reef ecosystems by ensuring high levels of primary production in oligotrophic environments. A previous study on organic matter degradation within biogenic carbonate and terrigenous silicate reef sands in the Red Sea suggested that observed sand-specific differences in microbial activity could be caused by variations in microbial biomass and diversity. Here, we tested this hypothesis by comparing bacterial abundance and community structure in both sand types, and by further exploring the structuring effects of time (season) and space (sediment depth, in/out-reef). Changes in bacterial community structure, as determined via automated ribosomal intergenic spacer analysis (ARISA), were primarily driven by sand mineralogy at specific seasons, sediment depths and reef locations. By coupling ARISA with 16S-ITS rRNA sequencing, we detected significant community shifts already at the bacterial class level, with Proteobacteria (Gamma-, Delta-, Alpha-) and Actinobacteria being prominent members of the highly diverse communities. Overall, our findings suggest that reef sand-associated bacterial communities vary substantially with sand type. Especially in synergy with environmental variation over time and space, mineralogical differences seem to play a central role in maintaining high levels of bacterial community heterogeneity. The local co-occurrence of carbonate and silicate sands may thus significantly increase the availability of microbial niches within a single coral reef ecosystem. PMID:21554515

Schöttner, Sandra; Pfitzner, Barbara; Grünke, Stefanie; Rasheed, Mohammed; Wild, Christian; Ramette, Alban

2011-05-09

58

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

59

Experimental degradation of oil in permeable sand from the Gulf of Aqaba, Red Sea  

Microsoft Academic Search

Degradation rates of light and heavy oil in permeable carbonate sands from the Gulf of Aqaba were investigated to evaluate the ability of sediments to degrade oil compounds. Silicate sands that are less permeable and different properties from carbonate sands were used for comparison. Estimates of oil degradation rates were based on oxygen consumption rates, calculated by incubating natural carbonate

Mohammad Rasheed; Tariq Al Najjar; Mohamad G. Al-Masri; Saima Mian

2011-01-01

60

Relations between red beds times and uranic mineralization at the area of north-west China, Shaanxi and Inner Mongolia.  

National Technical Information Service (NTIS)

Rad beds played an important role in the uranic mineralization. After analyzing the geological evolution in North-West China, Saanxi and Inner Mongolia the red beds is divided into six periods. The evolution rules at each period are studied. The authors f...

Q. Zhou Z. Quan

1989-01-01

61

Effect of Sand and Sawdust Bedding Materials on the Fecal Prevalence of Escherichia coli O157:H7 in Dairy Cows  

Microsoft Academic Search

Farm management practices that reduce the prevalence of food-borne pathogens in live animals are predicted to enhance food safety. To ascertain the potential role of livestock bedding in the ecology and epidemiology of Escherichia coli O157:H7 on farms, the survival of this pathogen in used-sand and used- sawdust dairy cow bedding was determined. Additionally, a longitudinal study of mature dairy

Jeffrey T. LeJeune; Michael D. Kauffman

2005-01-01

62

An Alternative Septage Treatment Method: Lime Stabilization/Sand-Bed Dewatering.  

National Technical Information Service (NTIS)

Few desirable methods exist for disposing of the sludge that is periodically pumped from septic tanks. This report describes the results obtained from a pilot study of one alternative septage treatment method-lime stabilization followed by covered sand-be...

E. T. Oppelt J. F. Kreissl W. A. Feige

1975-01-01

63

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

64

Nature of remagnetization of Lower Triassic red beds in southwestern China  

NASA Astrophysics Data System (ADS)

Widely distributed haematite-bearing red beds are an important source of palaeomagnetic field records. However, unresolved issues regarding remagnetization and inclination shallowing in red beds have questioned the reliability of the palaeomagnetic results obtained from such materials. In this study, we investigated the remagnetization mechanism in red beds from Lower Triassic sandstones in Yunnan Province, southwestern China. Our results indicate that the characteristic remanent magnetizations (ChRMs) of most samples (112/125) are dominated by only one component at temperatures 80-660 °C, with a mean direction of D/I= 0.9/46.6° (k= 440.2, ?95= 2.1°). The corresponding geomagnetic pole is 89.1°N, 331.7°E (k= 338.2, A95= 2.4°). This coincides with the present geomagnetic field, which is a strong indication that these ChRMs are remagnetized. Combined rock magnetic and microscope investigations reveal that the remagnetization is due to the acquisition of a chemical remanent magnetization (CRM) carried by authigenic maghemite and haematite. Despite the widespread remagnetization, about 7 per cent of the studied samples still record a magnetization that we consider to be primary that was isolated at high temperatures 610-660 °C, with a mean direction of D/I= 213.3/18.6° (k= 16.0, ?95= 11.7°). We propose that the CRM overprinting is controlled by the overlapping degree of the unblocking temperature between the CRM carried by the authigenic haematite and the primary remanent magnetization carried by the detrital haematite. Our results further suggest that microscope investigation, rock magnetic proxies for the haematite concentration and susceptibility-temperature curves are useful methods for pre-selecting samples suitable for isolating the primary remanence at this region. The linkage among the palaeomagnetic results, rock magnetic proxies and CRM remagnetization mechanism could be extended to other studies, although the detailed proxy would be different due to specific overprint process.

Liu, Chengying; Ge, Kunpeng; Zhang, Chunxia; Liu, Qingsong; Deng, Chenglong; Zhu, Rixiang

2011-12-01

65

A simplified Red Bed Inclination Correction: Case Study from the Permian Esterel Group of France.  

NASA Astrophysics Data System (ADS)

Magnetic anisotropy-based inclinations corrections have been performed in the paleomagnetic laboratory at Lehigh University, on both hematite and magnetite-bearing sedimentary rocks. Results of these corrections indicate a latitudinal variation of inclination shallowing with the formations initially located at mid latitudes suffering from more shallowing than those initially closer to the equator, consistent with the tan (Im)= f * tan (If) relationship observed by King (1955) for inclination shallowing, where Im is the measured inclination and If is the field inclination during deposition. Shallowing of the paleomagnetic vectors can be expressed in terms of the flattening factor f, that relates tan (Im) to tan (If). Anisotropy- derived hematite f factors from the Maritime Provinces of Canada and Northwest China were combined with f factors derived from corrections that use models of geomagnetic field secular variation (the EI technique of Tauxe and Kent, 2004) on red bed Formations from North America, Greenland and Europe. The dataset was used to derive a probability density function for f. The mean f value will allow a simplified inclination correction for hematite-bearing red bed formations that are suspected to be affected by inclination shallowing. This approach was tested by correcting the Permian Esterel Group red beds from France: using the distribution mean f factor of 0.64 (±0.11, ±1 standard deviation), the corrected red bed paleopole becomes statistically indistinguishable from the paleopole measured for the Esterel Group volcanic rocks that have not suffered from inclination shallowing. f data was also compiled for magnetite-bearing sedimentary rocks from the Perforada Formation and the Valle Group from Baja California, Mexico, the Pigeon Point Formation of Central California, the Ladd and the Point Loma Formations from Southern California, the Nanaimo Group of British Columbia and the Deer Lake Group of Newfoundland that have been corrected for inclination shallowing, yielding a most probable f factor of 0.67 (±0.06). Based on our results, the maximum amounts of shallowing that can be expected for sedimentary rocks is 12.4° for hematite-bearing rocks, and 11.8° for magnetite-bearing rocks. These values are statistically indistinguishable. Therefore, we combined the datasets and have obtained an f factor of 0.66 (±0.1) that can be used for either hematite or magnetite-bearing sedimentary rocks. A major implication of this result is that a rock's NRM, either acquired by chemical processes soon after deposition or by depositional processes that accurately record the ambient magnetic field, may be susceptible to similar amounts of inclination shallowing, most likely caused by burial compaction.

Bilardello, D.; Kodama, K. P.

2008-12-01

66

Sediment-level fluctuation in a mussel bed on a `protected' sand-gravel beach  

NASA Astrophysics Data System (ADS)

Studies of a dense population of the blue mussel ( Mytilus edulis) between an abrupt lower boundary at +0·6 m above MLLW, and an indistinct upper limit at +2·3 m above MLLW on a sand-gravel beach at Quartermaster Harbor, Vashon Island, WA, evaluated the effects of physical and biological factors on patterns of abundance and distribution. Winter storms caused little sediment movement high on the shore either inside or outside patches of mussels, but large fluctuations (> 3 cm) at mid- and low-shore levels sometimes caused burial and mortality. Even high mussel biomass (25 kg m -2) did not prevent large-scale sediment level change.

Landahl, John

1988-03-01

67

Experiments in eruption recovery: Channel bed and sediment transport adjustments as sand inputs decline  

Microsoft Academic Search

Transient sediment loading can alter channel bed conditions and sediment transport rates which complicates the prediction of sediment yields, yet evaluation of post-eruption sediment yields remains an important component of volcanic hazard assessment. The 1991 eruption of Mount Pinatubo, Philippines, introduced 1 km3 of loose, sandy, pyroclastic flow debris to the Pasig-Sacobia-Abacan basins. River recovery is ongoing as sediment is

K. B. Gran; D. R. Montgomery; D. Sutherland; T. E. Lisle

2004-01-01

68

Palaeomagnetism of Permian red beds in the contact aureole of the Tertiary Adamello intrusion (northern Italy)  

NASA Astrophysics Data System (ADS)

Permian clastic red beds of the Verrucano Lombardo formation have been contact metamorphosed by Eocene-Oligocene calc-alkaline intrusions of the Adamello massif (Southern Alps). The magnetization of the unmetamorphosed or at most anchimetamorphosed sediments outside the contact zone is controlled by pigmentary and detrital haematite. The pigment haematite is converted to biotite in the contact zone, where magnetite and pyrrhotite are also generated in the zone of highest-grade metamorphism. The detrital haematite (martite and titanohaematite), however, survives even in close proximity to the intrusion, where temperatures around 600°C have been reached. An apparent paradox is found: the structure of natural remanent magnetization (NRM) becomes less complex with increasing chemical changes owing to contact metamorphism. Except for viscous components, the NRM of the unmetamorphosed red beds consists of two magnetizations: an early acquired Permian component and a later overprint of Tertiary age. Owing to the natural chemical demagnetization, however, which removed the pigmentary haematite, a simple one-component NRM is often found in the metasediments of the contact zone. This magnetization is either of Permian origin, residing in the original detrital haematite, or of Tertiary age. The latter palaeomagnetic component is carried mainly by secondary haematite formed during contact metamorphism. The Permian magnetization has partly survived even in the highest metamorphic (andalusite) zone.

Kipfer, Rolf; Heller, Friedrich

1988-11-01

69

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

USGS Publications Warehouse

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

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

1973-01-01

70

Detection and Population Estimation for Small-Bodied Fishes in a Sand-Bed River  

Microsoft Academic Search

Multiple-pass removal by use of small-mesh seines within enclosed areas was performed to estimate numbers of nine small-bodied fish species at 17 sites in the Pecos River, New Mexico, during October 2007. Site-level population estimates were most precise for age-0 red shiners Cyprinella lutrensis (coefficient of variation [CV, calculated as SE\\/mean] = 0.02–0.06) and least precise for age-1 and older

Ann M. Widmer; Laura L. Burckhardt; Jon W. Kehmeier; Eric J. Gonzales; C. Nicolas Medley; Richard A. Valdez

2010-01-01

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

Technical note: Whole-pen assessments of nutrient excretion and digestibility from dairy replacement heifers housed in sand-bedded freestalls.  

PubMed

Our objectives were to describe and test refined procedures for quantifying excreta produced from whole pens of dairy heifers. Previous research efforts attempting to make whole-pen measurements of excreta output have been complicated by the use of organic bedding, which requires cumbersome analytical techniques to quantify excreta apart from the bedding. Research pens equipped with sand-bedded freestalls offer a unique opportunity for refinement of whole-pen fecal collection methods, primarily because sand-bedded freestall systems contain no organic bedding; therefore, concentrations of ash within the manure, sand, and feces can be used to correct for contamination of manure by sand bedding. This study was conducted on a subset of heifers from a larger production-scale feeding trial evaluating ensiled eastern gamagrass [Tripsacum dactyloides (L.) L.] haylage (EGG) that was incorporated into a corn silage/alfalfa haylage-based blended diet at rates of 0, 9.1, 18.3, or 27.4% of total DM. The diet without EGG also was offered on a limit-fed basis. Eighty Holstein dairy heifers were blocked (heavy weight, 424 ± 15.9 kg; light weight, 324 ± 22.4 kg) and then assigned to 10 individual pens containing 8 heifers/pen. One pen per block was assigned to each of the 5 research diets, and whole-pen fecal collections were conducted twice for each pen. Grab fecal samples also were gathered from individual heifers within each pen, and subsequent analysis of these whole-pen composites allowed reasonable estimates of OM and NDF excreta output. Under the conditions of our experimental design, pooled SEM for the excreta DM, OM, NDF, and NDF (ash corrected) output were 0.113, 0.085, 0.093, and 0.075 kg·heifer(-1)·d(-1), respectively. For DM excretion, this represented about one-third of the SEM reported for previous whole-pen collections from bedded-pack housing systems. Subsequent calculations of apparent DM and OM digestibilities indicated that the technique was sensitive, and linear trends (P ? 0.027) associated with the inclusion rates of EGG within the diet were detected. This technique allows estimation of apparent diet digestibilities on multiple animals simultaneously, thereby mitigating the need for isolating individual animals to obtain digestibility coefficients. The approach appears viable but requires hand labor for collections of multiple pens and thorough mixing of large volumes of manure as well as analytical corrections for sand ingested by lounging heifers. PMID:23965394

Coblentz, W K; Hoffman, P C; Esser, N M; Bertram, M G

2013-08-21

73

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

74

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

75

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

SciTech Connect

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

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

1991-03-01

76

Packed bed column studies for the removal of Acid blue 92 and Basic red 29 using non-conventional adsorbent  

Microsoft Academic Search

The adsorptive removal of Acid blue 92 and Basic red 29 dyes was achieved using a packed column prepared by Euphorbia antiquorum L activated carbon. The effects of various factors like influent concentration, flow rate and bed height were analysed. The column experiments using Euphorbia antiquorum L activated carbon showed that adsorption efficiency increases with increase in the influent concentration

P Sivakumar; P N Palanisamy

77

Extraction of energetics from sand using acetone: Acetone extraction of DNT from packed beds and stirred slurries of sand; recovery of acetone for reuse. Final report, 1 May 1995-31 June 1996  

SciTech Connect

A number of military industrial sites for production of energetic compounds (explosives, propellants, and pyrotechnics) have contaminated soils and lagoon sediments. Several methods exist for clean-up of these contaminated soils. The method of solvent extraction is expected to be competitive with the other methods provided that the acetone solvent can be recovered and reused in the process. The amount of solvent required for the separation impacts upon the operation of the extraction processes. The processes generally fall within two extremes: concentrated particle systems (such as in packed beds) or dilute particle systems (such as occur in slurries in stirred tank systems). This report contains the results of experiments conducted on packed bed and stirred tank acetone extraction of sand spiked with 2,4 Di Nitro Toluene (2,4 DNT). The overall economics of the acetone extraction process depends to a large extent on the recovery of the acetone for reuse. The results of this work show that acetone is effective in recovering energetics from sand either in packed beds or stirred tanks. The stirred tank extractor appears to be better than the packed bed extractor requiring less acetone per ton of soil and requiring a shorter contact time. The method that is most promising for recovery of the acetone is that of flashing with a cheap absorbent material such as wood chips to absorb the energetics. The overall cost analysis shows a savings of about $1.2 million per 50 thousand tons of soil washed. This work needs to be extended to clayey type soils and tests conducted on actual lagoon soils.

Chase, G.C.; Boggavarapu, R.; Tonangi, S.

1996-07-31

78

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

NASA Astrophysics Data System (ADS)

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

Bilardello, D.; Kodama, K. P.

2007-12-01

79

Sunlight\\/ZnO-mediated photocatalytic degradation of reactive red 22 using thin film flat bed flow photoreactor  

Microsoft Academic Search

Photocatalytic degradation of one of the most widely used cotton dyes, namely reactive red 22 (RR 22), was investigated in the presence of a thin film of ZnO photocatalyst using a thin film flat bed flow photoreactor under solar radiation. The effects of reaction parameters such as pH, amount of ZnO coating, flow rate and concentration of the dye solution

L. Selva Roselin; G. R. Rajarajeswari; Rosilda Selvin; V. Sadasivam; B. Sivasankar; K. Rengaraj

2002-01-01

80

Decolorization of Reactive Red K-2BP wastewater in fixed-bed column system packed sponge iron  

Microsoft Academic Search

The decolorization of Reactive Red K-2BP wastewater with sponge iron in a fixed-bed column system was evaluated at different influent water qualities (pH, dye concentration), particle diameter of sponge iron and filtrate rate. The decolorization efficiencies at influent pH of 6 were superior to those at influent pH of 5 and 7.5. The decolorization efficiency decreased with increments of filtration

Yan Wang; Mengchun Gao; Yandun Wang; Zichao Wang; Heng Yu

2010-01-01

81

Mapping the bathymetry of a turbid, sand-bed river using ground-based reflectance measurements and hyperspectral image data  

NASA Astrophysics Data System (ADS)

The Platte River in central Nebraska encompasses relatively stable, single-thread to island-braided reaches as well as wider, fully braided segments with highly mobile bar forms. Across this range of morphologies, suspended sediment and organic material contribute to turbid water conditions. In addition, the Platte is the focus of management activities intended to mitigate encroachment of vegetation and improve habitat for various migratory bird species, primarily by increasing the areal extent of shallow to slightly emergent mid-channel sand bars. The diversity of channel types and optical properties make this a challenging environment in which to implement a remote sensing approach, but the Platte also provides an opportunity for these methods to support management objectives. To evaluate the potential utility of remote sensing techniques along the Platte, we acquired hyperspectral image data, collected field spectra, and surveyed bed topography for three reaches. Ground-based measurements of reflectance R? were made above the water surface for flow depths d from 5 - 67 cm and a range of substrate types. An optimal band ratio analysis (OBRA) of these data, whereby regressions of log-transformed band ratios against measured depths were performed for all possible band combinations, yielded a strong, linear relationship (R2 = 0.95) between ln ({R593}/{R{647}) and d. Similar band ratio analyses were performed using reflectance spectra extracted from the hyperspectral image data for locations at which bed elevations were surveyed and compared to measured water surface elevations to calculate flow depths. Image-based OBRA produced variable results for the three sites. For a narrower, deeper reach lacking mobile mid-channel bars, a ln ({R490}/{R{638}) vs. d relation had an R2 of 0.83; applying this expression to the image generated a bathymetric map that agreed closely with our survey data. The other two sites featured fully braided morphologies, shallower depths, and numerous lobate bar forms, and image-based OBRA resulted in maximum R2 values of 0.47 and 0.53. Closer inspection of image-derived and surveyed cross-sections indicated that this poor agreement was partially explained by: 1) inaccurate geo-registration between the image and field data; 2) translation of the bar forms during the four days between the image acquisition and the completion of the field surveys; and 3) the presence of a range of depths within individual 0.75 m image pixels due to the abrupt variations in bathymetry associated with the bar-chute morphology. Examination of depth maps for the latter two reaches suggested that image-derived depths were actually more reliable than conventional accuracy metrics, such as R2, might seem to indicate. Moreover, applying the band ratio relation derived from field spectra directly to the image data yielded depth estimates that closely matched our field data. This latter finding implies that calibration based on field spectra is a viable alternative to pairing image pixels with ground-based depth measurements, which can be highly problematic for the reasons cited above.

Legleiter, C. J.; Kinzel, P. J.; Nelson, J. M.

2010-12-01

82

Phosphorus, nitrogen, and radionuclide retention and leaching from a Joel sand amended with red mud/gypsum  

SciTech Connect

The leaching of phosphorus (P), nitrogen (N), and radionuclides [sup 232]Th, [sup 226]Ra, [sup 228]Ra, and [sup 40]K from Joel sands amended with red mud/gypsum (RMG) at 9 rates (0, 2, 4, 8, 16, 32, 64, 128, and 256 t/ha) was measured using columns. Intense leaching conditions (34 mm/day for 12 days) and a high rate of applied P (320 kg/ha as superphosphate) and N (680 kg/ha as ammonium nitrate) were used to simulate extremes of irrigated vegetable production on the Swan Coastal Plain. Addition of the highest rate of RMG (256 t/ha) reduced leaching of fertiliser P and ammonium-nitrogen (NH4-N) by 85% and 50%, respectively, compared with 0 t/ha after 12 days. At 64 t RMG/ha P leaching was reduced 50% compared with 0 t/ha. Nitrate-nitrogen (NO3-N) leaching was not affected by addition of RMG. Reduced leaching of NH4-N was attributed to an increase in cation exchange capacity of the soil with the addition of RMG. Bicarbonate-extractable P in the soil increased with rate of RMG to >50 [mu]g P/g soil at 256 t/ha. This indicates that soil testing of residual P could be used to reduce P inputs to vegetable crops after soils were amended with RMG. This would further reduce the impact of vegetable production on the water systems of the Swan Coastal Plain and extend the period of effectiveness of RMG amended soils. The increase in [sup 232]Th specific activity in Joel sand amended with RMG was well below statutory limits even at the highest rate. Neither [sup 40]K nor [sup 226]Ra were detectable in RMG amended sands up to 256 t RMG/ha. There was no evidence of leaching of [sup 226]Ra or [sup 228]Ra at any rate of RMG. These results suggest that the use of RMG amendment on commercial horticultural properties on the Swan Coastal Plain could be feasible. 30 refs., 7 figs., 2 tabs.

McPharlin, L.R. (Dept. of Agriculture Western Australia, South Perth (Australia)); Jeffery, R.C. (Chemistry Centre, East Perth (Australia)); Toussaint, L.F. (Western Australia Dept. of Health, Nedlands (Australia)); Cooper, M. (Australian Radiation Labs., Yallambie, Victoria (Australia))

1994-01-01

83

New Early Cretaceous paleomagnetic data from volcanic and red beds of the eastern Qaidam Block and its implications for tectonics of Central Asia  

NASA Astrophysics Data System (ADS)

In order to better understand anomalously low paleomagnetic inclinations in the Cretaceous rocks of central Asia, a combined geochronologic and paleomagnetic investigation has been performed on Cretaceous basalt sequences intercalated with red beds from Zeku area in the eastern Qaidam Block, northeastern Tibetan Plateau. Potassium argon (K Ar) dating indicates that the basalt sequences are of Early Cretaceous age (89.9 ± 2.8 to 112.1 ± 2.4 Ma). Isothermal remanent magnetization (IRM), thermal demagnetization of a three-component IRM, and Curie point experiment suggest that magnetite and hematite dominate in red beds, magnetite in basalt flows. Stepwise thermal demagnetization successfully isolated stable characteristic remanent magnetization (ChRM) from 7 lava flows and 12 red beds sites. The ChRMs of red bed and basalt sites pass fold test and likely represent primary remanent magnetization. The tilt-corrected mean direction from red bed sites (basalts plus baked red bed site) is Ds = 18.4°, Is = 55.3°, ?s = 69.1, ?95 = 5.5°, N = 11 sites (Ds = 16.1°, Is = 52.0°, ?s = 42.6, ?95 = 8.6°, N = 8), corresponding to a pole at 75.2°N, 182.3°E with A95 = 7.07° (76.9°N, 194.9°E with A95 = 10.0°), respectively. The consistent inclination recorded in red beds and basalts implies no significant inclination shallowing caused by deposition compaction in red beds from the studied area. Compared with the Early Cretaceous poles from the North China Block (NCB) or Eurasia, insignificant post-Early Cretaceous northward motion may have occurred between the Qaidam Block and the NCB. On the basis of the existing regional paleomagnetic data, the Qaidam Block has not experienced wholescale vertical axis rotation since the Early Cretaceous with respect to NCB.

Sun, Zhiming; Yang, Zhenyu; Pei, Junling; Yang, Tianshui; Wang, Xisheng

2006-03-01

84

Field studies on factors affecting very fine and ultra fine particulate organic matter deposition in low-gradient sand-bed streams  

NASA Astrophysics Data System (ADS)

The knowledge on particle deposition in streams is mainly based on investigations in mountain streams. No data exist from low-gradient sand-bed streams that largely differ in the morphological and hydraulic factors proposed to affect deposition. To identify physical control on particle deposition in low-gradient streams, we assessed deposition of very fine and ultra fine organic particulate matter in 18 sand-bed stream reaches. We added particles derived from lake sediment and assessed the mean transport distance SP and the deposition velocity vdep. Additionally, reach hydraulics were estimated by injections of a conservative solute tracer (NaCl). Among the low-gradient streams, particle deposition kinetics were variable but similar to deposition in mountain streams. SP was solely related to the flow velocity. This relation was confirmed when comprising published data on deposition of fine organic particles. An association between particle deposition and transient storage factors was insignificant. We found significance of the transient storage to SP only for repeated measures within a single reach, when flow velocity and benthic conditions were nearly constant. Measured vdep/vfall ratios were much larger than unity in most reaches. Evidence from this relation suggests that the vertical transport of very fine and ultra fine organic particulate matter through the water column was caused mainly by vertical mixing. Copyright

Hünken, Andreas; Mutz, Michael

2007-02-01

85

Nugget-Navaho-Aztec sandstone: interaction of eolian sand sea with Andean-type volcanic arc  

SciTech Connect

The Nugget-Navaho-Aztec sand sea was deposited east of an Andean-type volcanic arc. During the early stage of eolian deposition, fluvially transported sand was concentrated in the marine littoral zone and returned inland by onshore winds from the northwest. With progressive development of the arc, the sea withdrew. Wind direction changed from northwest to northeast. Previously deposited eolian sand was transported southwestward into the volcanic arc. Proximity of the arc can be detected with great difficulty by examining eolian and underlying red-bed facies. In southern Nevada, the volcanic arc is undetectable in eolian facies, but thin sandstone beds containing volcanic clasts or weathered feldspar in the finer grained red-bed facies indicate arc volcanism; volcanic clasts are distinct in a basal conglomerate. Westward into California, the sub-Aztec Sandstone contains volcanic pebbles. The upper part of the Aztec Sandstone contains a 1 to 2-m thick volcaniclastic siltstone. Farther west, the Aztec Sandstone is interbedded with volcanic flows, ash flows, and flow breccias. These rocks might easily be mistaken for red beds in well cores or cuttings. Sand in sets of large-scale cross-beds remain virtually identical in composition and texture to sand in eolian facies of the Colorado Plateau. Where sets of eolian cross-beds lie on volcanics, the quartzose sandstone contains pebble to cobble-size volcanic clasts. Locally, cross-bed sets of yellowish-white, quartzose sandstone alternate with purplish-gray cross-bed sets containing numerous pebble to cobble-size volcanic clasts. The ability to recognize volcanic indicators within Nugget-Navaho-Aztec eolian facies is important in delineating the western margin of the back-arc eolian basin.

Marzolf, J.E.

1986-05-01

86

Pilot-scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 1. Final project summary report, September 1993October 1995  

Microsoft Academic Search

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is

W. Scoville; R. Hoye; P. Acharya; J. Martin

1995-01-01

87

Pilot scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 2. Final project summary report, September 1993October 1995  

Microsoft Academic Search

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is

W. Scoville; R. Hoye; P. Acharya; J. Martin

1995-01-01

88

Pilot scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 3. Final project summary report, September 1993October 1995  

Microsoft Academic Search

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is

W. Scoville; R. Hoye; P. Acharya; J. Martin

1995-01-01

89

Pilot scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 4. Final project summary report, September 1993October 1995  

Microsoft Academic Search

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is

W. Scoville; R. Hoye; P. Acharya; J. Martin

1995-01-01

90

New and revisited paleomagnetic data from Permian-Triassic red beds: Two kinematic domains in the west-central Pyrenees  

NASA Astrophysics Data System (ADS)

New paleomagnetic results of Permian-Triassic red beds from Bielsa, Aure and Somport-Anayet sectors in the Pyrenean Axial Zone are presented and combined with revisited and reviewed paleomagnetic data from the west-central Pyrenees. The paleomagnetic data from the red beds vary between different sectors that share similar structural position; i.e. whilst all sectors share the existence of a characteristic prefolding component, a Cenozoic postfolding component is found only in one area but not in other areas with similar structural position and kinematics. Previous paleomagnetic data to the west of the studied zone reveal a pre-Turonian remagnetization component, but this secondary component is not found in an area that shares a similar structural position (Aure). This variability suggests that the paleomagnetic behavior is the result of a series of factors related to the particular tectonic history of the region (sedimentation, burial, and deformation during basin inversion) and therefore paleomagnetic data demands careful assessment in order to unravel the kinematics of areas with equivalent structural positions in orogens.However, important kinematic implications that hold in the Pyrenees can be inferred from the restoration of the Permian-Triassic characteristic magnetizations to positions previous to the paleomagnetic rotations recorded by Cretaceous or Cenozoic paleomagnetic data. The restoration reveals on one hand the lack of large rotations in the South Pyrenenan Zone except in the Nogueras area, according to Bates (1989), and on the other hand, the contrasting rotations recorded to the west of the studied zone, in the Paleozoic Basque Massifs (PBM) and the South-Pyrenean Zone, indicating the existence of two different tectonic domains in the west-central sector of the Pyrenees. The strong clockwise rotations postdating the Early Cretaceous remagnetization that are recorded in the PBM and in the North Pyreneean Zone, suggest a late dextral shear deformation affecting areas near the North Pyrenean Fault Zone.

Oliva-Urcia, Belén; Pueyo, Emilio L.; Larrasoaña, Juan Cruz; Casas, Antonio M.; Román-Berdiel, Teresa; van der Voo, Rob; Scholger, Robert

2012-02-01

91

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...

92

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

93

The Cyborg Astrobiologist: Scouting Red Beds for Uncommon Features with Geological Significance  

Microsoft Academic Search

Abstract The ‘Cyborg Astrobiologist’ has undergone a second geologi cal field trial, at a site in northern Guadalajara, Spain, near Riba de Santiuste. The site at Riba de Santiuste is dominated by layered deposits of red sandstones. The Cyborg Astrobiologist is a wearable,computer,and video camera system that has demonstrated,a capability to find uncommon interest points in geological imagery in realtime

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

2005-01-01

94

Residues from bauxite?mining (red mud) increase phosphorus retention of a joel sand without reducing yield of carrots  

Microsoft Academic Search

Carrots were grown on a Joel sand amended with several levels of applied gypsum?treated bauxite residue (RMG) up to 240 t?ha, to test whether the residue reduces phosphorus (P) leaching when applied to the soil. Phosphorus sorption, measured using the Modified Phosphorus Retention Index (PRIM), was initially 30 at 2401 RMG ha due to a combination of iron and aluminum

W. J. Robertson; R. C. Jeffery; I. R. McPharlin

1997-01-01

95

Inclination variation in the Late Jurassic to Eocene red beds from southeast Asia: lithological to locality scale approach  

NASA Astrophysics Data System (ADS)

Shallow palaeomagnetic inclinations have been frequently reported from the red beds of central and southeast Asia. To trace the origin of this phenomenon, inclination variation in southeast Asia is examined on lithological to locality scale. Lithological aspect of this variation has been studied using the Early Cretaceous Bailong and Cangxi formations of the Bazhong area (32.1°N, 106.7°E), the northern Sichuan Basin. Samples from 36 sites, consisting 18 pairs of successive sandstones and mudstones layers, were collected for this purpose from a synclinal structure. Stepwise thermal demagnetization of most samples revealed the presence of stable characteristic remanent magnetization, which is generally unblocked by 680 °C. Positive fold and reversal tests suggest a primary origin for this component, yielding the Early Cretaceous palaeomagnetic direction of declination/inclination = 20.9°/26.5° (ks= 37.2, ?95= 4.4°, N= 30). 10 pairs of sandstone and mudstone layers show almost identical inclinations (Isandstones= 23.3°± 3.7° and Imudstones= 24.7°± 2.4°), but 27° shallower than that expected from the Eurasian apparent polar wander paths (APWPs), indicating that no lithological variation in inclination has occurred. Location-wise variation in inclination shallowing is examined through palaeomagnetic data from Late Jurassic to Eocene red beds distributed around southeast Asia. Based on these investigations, no inclination shallowing is observed in the eastern part of the South China Block (SCB), whereas large degree of shallowing is observed in the Sichuan and Xining-Ninhe basins. Variation in inclination shallowing from one sedimentary basin to another could probably be caused by changes in the depositional environment. The eastern part of the SCB, where no inclination shallowing have been observed, is characterized by Basin and Range type tectono-geological setting. In contrast, the foreland basins are bounded to the north by east-west striking high altitude orogenic belt. Swift development of these basins as a result of flexural subsidence is the most likely reason for inclination shallowing.

Sato, Shun; Yang, Zhenyu; Tong, Yobo; Fujihara, Makoto; Zaman, Haider; Yokoyama, Masahiko; Kitada, Kazuya; Otofuji, Yo-Ichiro

2011-08-01

96

Pilot scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 2. Final project summary report, September 1993-October 1995  

SciTech Connect

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is not currently available for testing and the test site (host facility) where the demonstrations will be conducted has not been identified, these documents are intended to be generic in nature.

Scoville, W.; Hoye, R.; Acharya, P.; Martin, J.

1995-10-11

97

Pilot-scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 1. Final project summary report, September 1993-October 1995  

SciTech Connect

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is not currently available for testing and the test site (host facility) where the demonstrations will be conducted has not been identified, these documents are intended to be generic in nature.

Scoville, W.; Hoye, R.; Acharya, P.; Martin, J.

1995-10-01

98

Pilot scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 3. Final project summary report, September 1993-October 1995  

SciTech Connect

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is not currently available for testing and the test site (host facility) where the demonstrations will be conducted has not been identified, these documents are intended to be generic in nature.

Scoville, W.; Hoye, R.; Acharya, P.; Martin, J.

1995-10-11

99

Pilot scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Volume 4. Final project summary report, September 1993-October 1995  

SciTech Connect

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The Project Summary Report presents the conceptual designs. Because red water is not currently available for testing and the test site (host facility) where the demonstrations will be conducted has not been identified, these documents are intended to be generic in nature.

Scoville, W.; Hoye, R.; Acharya, P.; Martin, J.

1995-10-11

100

Health and safety plan for pilot-scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Final report, September 1993October 1995  

Microsoft Academic Search

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). This Project Summary Report and the Test Plan and Health and Safety

W. Scoville; R. Hoye; P. Acharya; J. Martin

1995-01-01

101

Test plan for pilot-scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Final report, September 1993October 1995  

Microsoft Academic Search

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The project objectives included development of a Test Plan and a Health

W. Scoville; R. Hoye; P. Acharya; J. Martin

1995-01-01

102

Palaeomagnetism and magnetic anisotropy of Carboniferous red beds from the Maritime Provinces of Canada: evidence for shallow palaeomagnetic inclinations and implications for North American apparent polar wander  

NASA Astrophysics Data System (ADS)

A palaeomagnetic and magnetic anisotropy study was conducted on the lower-middle Carboniferous Maringouin and Shepody red bed formations of the Maritime Provinces of Canada to detect and correct inclination shallowing. Because of the shallow inclinations commonly observed in red beds and the strong dependence of North America's Palaeo-Mesozoic apparent polar wander (APW) on red beds, inclination shallowing may substantially affect large portions of North America's APW path. Hematite is the primary magnetic mineral carrier in these red beds, accompanied by secondary magnetite, maghemite, goethite and pigmentary hematite. Thermal and chemical demagnetization of the Shepody Fm. successfully isolated characteristic remanence directions of D = 177°, I = 20.4°, ?95 = 6.5°, N = 19 and D = 177.8° I = 17.7°, ?95 = 6.9°, N = 16, respectively. Thermal demagnetization of the Maringouin Fm. isolated a characteristic remanence direction of D = 178.7°, I = 24.9°, ?95 = 14.5°, N = 9. High field anisotropy of isothermal remanence followed by alternating field and thermal cleaning on leached samples was used to isolate the fabric of hematite. Individual particle anisotropy was measured directly from magnetic separates using a new technique. Hematite's magnetic fabric and particle anisotropy were used to apply an inclination correction. Our inclination corrections indicate up to 10° of inclination shallowing, corresponding to corrected palaeopole positions of 27.2°N, 118.3°E, A95 = 6.2° and 27.4°N, 117.2°E, A95 = 13.1° for the Shepody and Maringouin formations, respectively. This correction corresponds to a ~ 6° increase in colatitude for Carboniferous North America, which translates into approximately a 650 km change in North America's palaeogeographic position. The proposed position of North America supports a Pangea B-type reconstruction.

Bilardello, Dario; Kodama, Kenneth P.

2010-03-01

103

Burning Characteristics of Non-Spread Diffusion Flames of Liquid Fuel Soaked in Porous Beds  

Microsoft Academic Search

An experimental study was conducted to investigate the effects of sand size and sand layer depth on the burning characteristics of non spread diffusion flames of liquid fuel soaked in porous beds. Sand beds with sand sizes from 0.12 to 3.18 mm and sand layer depths from 50 to 80 mm were chosen as the porous beds. Pure methanol was

Wenjun Kong; Christopher Y. H. Chao; Jinghong Wang

2002-01-01

104

Deceleration of projectiles in sand  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

105

Regeneration of sand waves after dredging  

Microsoft Academic Search

Sand waves are large bed waves on the seabed, being a few metres high and lying hundreds of metres apart. In some cases, these sand waves occur in navigation channels. If these sand waves reduce the water depth to an unacceptable level and hinder navigation, they need to be dredged. It has been observed in the Bisanseto Channel in Japan

M. A. F. Knaapen; S. J. M. H. Hulscher

2002-01-01

106

Vertical profiles of aeolian sand mass flux  

Microsoft Academic Search

Vertical profiles of the horizontal mass flux of blown sand are investigated experimentally using a passive vertical array in a wind tunnel. Considering lower sampling efficiency of the sand trap in the near-bed region, this investigation is complemented by the measurements of the longitudinal profiles of mass flux made using a horizontal sand trap. The experiments were conducted with two

J. R Ni; Z. S Li; C Mendoza

2003-01-01

107

Phosphorus adsorption maximum of sands for use as media in subsurface flow constructed reed beds as measured by the Langmuir isotherm  

Microsoft Academic Search

The P-adsorption capacities of 13 Danish sands were studied by short-term isotherm batch experiments and related to the physico-chemical characteristics of the sands. The maximum P-adsorption capacities (Q) and P-binding energy constants (b) were calculated using the Langmuir-isotherm model. The Freundlich model was also used, but it was not useful for the description of adsorption phenomena per se since it

M. Del Bubba; C. A. Arias; H. Brix

2003-01-01

108

Mystery Sand  

NSDL National Science Digital Library

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

Sciencenter

2012-01-01

109

Health and safety plan for pilot-scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Final report, September 1993-October 1995  

SciTech Connect

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). This Project Summary Report and the Test Plan and Health and Safety Plan are intended to serve as guides for development of complete project plans when the technology demonstration program is implemented. Because red water is not currently available for testing and the test site (host facility) where the demonstrations will be conducted has not been identified, these documents are intended to be generic in nature.

Scoville, W.; Hoye, R.; Acharya, P.; Martin, J.

1995-10-11

110

Test plan for pilot-scale demonstration of red water treatment by wet air oxidation and circulating bed combustion. Final report, September 1993-October 1995  

SciTech Connect

As part of the Army`s ongoing research and development program related to red water (KO47) treatment, the U.S. Army Environmental Center (USAEC) contracted IT Corporation to prepare conceptual designs and plans for pilot scale demonstrations of two treatment technologies: wet air oxidation (WAO) and circulating bed combustion (CBC). The project objectives included development of a Test Plan and a Health and Safety Plan for these demonstrations. The Project Summary Report presents the conceptual designs. This Project Summary Report and the Test Plan and Health and Safety Plan are intended to serve as guides for development of complete project plans when the technology demonstration program is implemented. Because red water is not currently available for testing and the test site (host facility) where the demonstrations will be conducted has not been identified, these documents are intended to be generic in nature.

Scoville, W.; Hoye, R.; Acharya, P.; Martin, J.

1995-10-11

111

Visualization of bed material movement in a simulated fluidized bed heat exchanger by neutron radiography  

Microsoft Academic Search

The bulk movement of fluidized bed material was visualized by neutron radiography by introducing tracers into the bed materials. The simulated fluidized bed consisted of aluminum plates, and the bed material was sand of 99.7% SiO2 (mean diameter: 0.218mm, density: 2555kg\\/m3). Both materials were almost transparent to neutrons. Then the sand was colored by the contamination of the sand coated

Hisashi Umekawa; Mamoru Ozawa; Nobuyuki Takenaka; Masahito Matsubayashi

1999-01-01

112

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

PubMed

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. The results showed that high temperature can improve the combustion efficiency and decrease CO emission. Moreover, increasing the fluidized velocity suppressed CO formation. In addition to temperature and fluidized velocity, the bed material also played an important role during cedar pellet combustion. Coarse bed materials were better than fine materials. In these test runs, the CO emission varied from 20 to 189 ppm, CO2 emission ranged from 5.7% to 19.5%, while NOx emission was quite stable at about 220 ppm. PMID:17869096

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

2007-09-14

113

Electric field in windblown sand flux with thermal diffusion  

Microsoft Academic Search

A theoretical model considering thermal diffusion (TD) from a sand bed is suggested in this paper to account for the effect of both TD and the electric field produced by charged sand grains during the evolution of windblown sand flux, where the coupled interaction among wind speeds in the vertical and the horizontal directions, sand movement (saltation, suspension, and creep),

Gaowei Yue; Xiaojing Zheng

2006-01-01

114

Computational simulations of blown sand flux over complex microtopography  

Microsoft Academic Search

Current research on sand saltation concentrates on wind tunnel experiment, theoretical analysis and numerical simulation of sand saltation at ideal and controllable conditions, for example, time-invariant wind speed and flat sand bed. However, these somehow idealized theoretical analyses and numerical simulations can not accurately predict sand movements in field environments, which are generally composed of surface obstacles including dunes and

Huang Ning; Shi Feng

2009-01-01

115

A Paleomagnetic and Magnetic Anisotropy Study of the Carboniferous Maringouin Formation, New Brunswick, Canada: Possible Evidence for Inclination Shallowing in Continental Red Beds  

NASA Astrophysics Data System (ADS)

Continental red sedimentary rocks have stable paleomagnetic signals and have been used extensively to delineate the apparent polar wander path of North America in the Paleozoic. Previous paleomagnetic and rock magnetic work on the Mississippian Mauch Chunk Formation red beds from northeastern Pennsylvania suggests that these rocks have suffered from significant inclination shallowing. The corrected paleopole for the Mauch Chunk lies far from the Carboniferous part of the current North American apparent polar wander path [Tan and Kodama, 2002]. In order to check the validity of this new paleopole for the Mauch Chunk and the prevalence of inclination shallowing in red beds, we conducted a paleomagnetic and magnetic anisotropy study of the coeval, Carboniferous age Maringouin Formation from New Brunswick, Canada. One hundred oriented samples were collected from 11 sites in the Maringouin Formation on the Maringouin Peninsula, New Brunswick. Eight sites were sampled from sea cliffs exposing the south limb of an east-west trending anticline and 3 sites were sampled from the north limb of the fold. Thermal demagnetization was conducted on 5 samples from each site in at least 13 steps up to 675° C. Preliminary thermal demagnetization results from four sites from the south limb of the fold isolated a mean direction (D=177.4° , I=22.0° , K=8.5) similar to that found in an earlier study of the Maringouin Formation [DiVenere and Opdyke, 1990]. Chemical demagnetization in 3M HCl for up to 6 weeks was also used to isolate the characteristic remanence (ChRM) from 4 samples from each site. Anisotropy of magnetic susceptibility (AMS) was measured at each chemical demagnetization step to determine the AMS of the grains carrying the ChRM. Preliminary results from 3 sites indicate a shallower ChRM was isolated by chemical demagnetization (D=181.2° , I=2.6° , K=13.3), than by thermal demagnetization. The AMS data from 4 sites were used to make a correction for inclination shallowing as proposed by Tan and Kodama [2002] in their work on the Mauch Chunk Formation in Pennsylvania. The thermal demagnetization results from these sites were corrected by the AMS isolated between 3 and 6 weeks of chemical demagnetization. The results from the Maringouin Formation show a 22° steepening of the inclination once it is corrected for shallowing. The corrected paleopole for the Maringouin Formation lies at lat=21.6° N, long=117.0° E, ? 95=29.9° which is within 13° of the corrected Mauch Chunk paleopole of Tan and Kodama [2002]. It is also reasonably close to a new, inclination-corrected paleopole from the Carboniferous magnetite-bearing Conemaugh Group sedimentary rocks of southwestern Pennsylvaniva (25° N, 106.5° E) [Kodama, 2004]. These results support the need for an inclination shallowing correction on continental red beds. They also may suggest that the North American apparent polar wander path, where it is heavily dependent on red bed-based paleomagnetic data, needs to be re-evaluated.

Newton, M. L.; Kodama, K. P.

2004-05-01

116

Differences Among Fish Assemblages Associated with Nearshore Posidonia oceanica Seagrass Beds, Rocky–algal Reefs and Unvegetated Sand Habitats in the Adriatic Sea  

Microsoft Academic Search

Fish assemblages associated with nearshore Posidonia oceanica seagrass beds, rocky–algal reefs and unvegetated sandy substrates were studied at two sampling localities, Otranto (Apulian coast) and S. Domino (Tremiti Islands), located in the Southern and Central Adriatic Seas (Mediterranean Sea), respectively. Data were collected in situ by using non-destructive diver visual census methodology. A higher species richness and fish density were

P. Guidetti

2000-01-01

117

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

118

Rock magnetic evidence for inclination shallowing in the Passaic Formation red beds from the Newark basin and a systematic bias of the Late Triassic apparent polar wander path for North America  

NASA Astrophysics Data System (ADS)

The latest Triassic and earliest Jurassic red beds from the Newark basin possess paleomagnetic inclinations that are ˜ 10° shallower than the inclinations carried by coeval volcanic rocks. It has been suggested that the difference might be due either to inclination shallowing of the sediments or to remagnetization of the volcanic rocks during a Middle Jurassic hydrothermal event. Either explanation would in turn yield significantly different apparent polar wander paths (APWPs) for the Late Triassic and Early Jurassic of North America. Here we present paleomagnetic and magnetic anisotropy data for the latest Triassic Passaic Formation red beds, which reveal deposition and/or compaction fabrics with 10% anisotropy of the high unblocking temperature, reversed polarity remanent magnetization. Inclination correction for the red beds yields similar directions to that carried by the earliest Jurassic volcanic rocks, indicating that inclination shallowing is the major cause for the difference in paleomagnetic pole position between the red beds and the volcanic rocks. Comparison of the inclination corrected data with the Late Triassic North American APWP shows a systematic error in the APWP, likely due to inclination shallowing. In turn, this error may be even more significant for much of the Paleozoic part of the North American APWP.

Tan, Xiaodong; Kodama, Kenneth P.; Gilder, Stuart; Courtillot, Vincent

2007-02-01

119

A wind tunnel experiment of sand transport and its comparison with the Werner model  

Microsoft Academic Search

We carried out a wind tunnel experiment on aeolian transport of sand. Fluorescence-dyed grains of sand were embedded in the sand bed in a wind tunnel, and their dispersion was recorded by a video camera. Dispersion of colored sand both downwind and in the crosswind direction are examined. The concentration of colored sand decreases as an exponential function of the

Y. Hatano; Y. Kanda; K. Udo; S. Takewaka; R. Ueki; N. Hatano; H. Mouri; M. Chiba; K. Kurihara; H. Nishimura

2004-01-01

120

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

121

Sand Dunes  

NSDL National Science Digital Library

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

Enright, Rachel

122

Have the northwest Negev dunefield sands reddened since their deposition?  

Microsoft Academic Search

Sand grain coating redness has been extensively both in coastal and inland desert dunes. In Israel, sand redness has been quantified by calculating a spectral redness index (RI) using single RGB bands (RI= R2\\/(B*G3)) from reflectance spectroscopy. The RI values have been correlated to ferric oxide mass that was dissolved from sand grain coatings (Ben Dor et al., 2006; Tsoar

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

2010-01-01

123

The origin, classification and modelling of sand banks and ridges  

Microsoft Academic Search

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

Keith R Dyer; David A Huntley

1999-01-01

124

Influence of sand grain diameter and wind velocity on lift-off velocities of sand particles.  

PubMed

In this paper, the velocities of sand particles near the sand bed in the saltation cloud were measured in a wind tunnel through an improved experimental scheme of the Particle Image Velocimetry (PIV) system. The influences of the diameter of sand particles in the saltation cloud and wind velocity on the probability distribution function (PDF) of lift-off velocities of sand particles were investigated. Results demonstrate that for the sand particles saltating above the sand bed with the mean grain diameter (d m = 0.3 mm), smaller and larger ones have the same velocity distribution, and wind velocity has no obvious influence on the distribution shape of the lift-off velocities, i.e., the PDFs of the horizontal and vertical lift-off velocities both follow a lognormal distribution, but the diameter of sand particles in the saltation cloud and wind velocity have an influence on the parameters of the PDF of horizontal and vertical lift-off velocities. Eventually, we present formulas to describe the PDF of lift-off velocities of sand particles with regard to the influence of wind velocity and the diameter of sand particles in the saltation cloud above the sand bed with d m = 0.3 mm. PMID:23695368

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

2013-05-24

125

Molecular phylogeny of the subfamily Amphistichinae (Teleostei: Embiotocidae) reveals parallel divergent evolution of red pigmentation in two rapidly evolving lineages of sand-dwelling surfperch.  

PubMed

Pigment evolution was reconstructed in the subfamily Amphistichinae, a six-species clade of the surfperches, family Embiotocidae. Assignment was confirmed for all species within the subfamily, but low levels of differentiation were found among species within the subfamily, suggesting a recent radiation. The new phylogeny differs from previous hypotheses by the placement of the spotfin surfperch Hyperprosopon anale at the base of the subfamily, while still preserving the calico surfperch Amphistichus koelzi and the redtailed surfperch Amphistichus rhodoterus as sister species. Phenotypically, A. rhodoterus, A. koelzi and the silver surfperch Hyperprosopon ellipticum express high levels of red pigmentation. The barred surfperch, Amphistichus argenteus and the walleye surfperch Hyperprosopon argenteum express little to no red pigment, while basal H. anale expresses an intermediate amount of red pigment. Red pigmentation is proposed to have experienced parallel divergent evolution in each genus within the subfamily. PMID:21781095

Westphal, M F; Morey, S R; Uyeda, J C; Morgan, T J

2011-07-14

126

Anomalous sand deposit associated with evidence of late Holocene uplift near Bremerton, Washington  

NASA Astrophysics Data System (ADS)

The origins of a puzzling sand unit at the head of Sinclair Inlet likely include a Puget Sound tsunami and its return flow but may also include sand volcanoes, debris flows, or both.. The inlet, a branch of Puget Sound 22 km west of Seattle, contains at its head an intertidal mudflat that is fringed by partly urbanized tidal marshes and alder swamps. Cores and pits in these remnant wetlands reveal an abrupt upward change from tidal flats to freshwater forest that probably resulted from uplift during the Seattle fault earthquake of A.D. 900-930 or during slip of similar age on the Tacoma fault. The puzzling sand unit formed at or about the time of this uplift. The unit consists of silty fine sand commonly 1 m in thickess. It has a sharp contact with shelly mudflat deposits below and a sharp to gradational contact with overlying peat. The lower part of this peat contains the growth-position roots of western red cedar (Thuja placata), and the upper part forms the soil of modern salt marshes. We found the sand unit, 1.1 m thick in areas, along 0.5 km of the upper inlet's shoreline, beneath modern tidal marshes and alder swamps. The unit contains at least three parts: a basal subunit that fines upward from medium and coarse sand to fine sand and silt; a thin (less than 1 cm thick) clay bed, commonly with flame structures; and a capping subunit up to 50 cm thick that is dominated by silty fine to medium sand but which also contains pebbles derived from rock and glacial outwash. Preliminary diatom analysis shows the unit contains diatoms from a brackish environment. A possibly related sand unit lies 0.8 km inland, up the valley of Gorst Creek. Its thickness is in the range 0.2-1.0 m as observed thus far in creek banks and in pits at a nearby park. Unlike the sand that borders the inlet, it contains trough cross-bedding. We are investigating the relationship between this deposit and the silty sand deposit in the tide flats. Preliminary diatom analysis did not find any diatoms in this deposit.

Martin, M. E.; Maxcia, C.; Gerardi, F.; Bourgeois, J.

2007-12-01

127

Booming Sands  

NSDL National Science Digital Library

This video segment, adapted from NOVA scienceNOW, presents basic concepts of physics behind booming sand dunes. See how surface tension affects potential and kinetic energy and how it all works together to create sound.

Foundation, Wgbh E.

2007-04-19

128

Deceleration of Projectiles in Sand  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

129

Larval abundance and recruitment of the sand dollar Dendraster excentricus in Monterey Bay, California, USA  

Microsoft Academic Search

Seasonal abundance of planktonic larvae of the sand dollar Dendraster excentricus was determined in Monterey Bay, California, USA. Larvae were counted from two offshore stations and also over a coastal sand dollar bed, and these data were compared with settlement in the sand dollar bed, with adult population structure and with adult reproductive condition. These measurements were made during the

R. A. Cameron; S. S. Rumrill

1982-01-01

130

Dual Fluidized Bed Biomass Gasification  

SciTech Connect

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

None

2005-09-30

131

Behavior of Windblown Sand on Mars: Results from SingleParticle Experiments  

Microsoft Academic Search

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

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

1999-01-01

132

Deep-water massive sands: nature, origin and hydrocarbon implications  

Microsoft Academic Search

Deep-water massive sands (DWMS) are here defined as very thick (>1 m) sand beds or units that are devoid of primary sedimentary structures and that occur in association with other deep-water sediments — the massive sand facies association. Following careful examination of some 70 examples of massive sands drawn from deep-water successions of all ages and lithologies, we are confident that

Dorrik A. V Stow; Melissa Johansson

2000-01-01

133

Visualization of bed material movement in a simulated fluidized bed heat exchanger by neutron radiography  

NASA Astrophysics Data System (ADS)

The bulk movement of fluidized bed material was visualized by neutron radiography by introducing tracers into the bed materials. The simulated fluidized bed consisted of aluminum plates, and the bed material was sand of 99.7% SiO2 (mean diameter: 0.218mm, density: 2555kg/m3). Both materials were almost transparent to neutrons. Then the sand was colored by the contamination of the sand coated by CdSO4. Tracer particles of about 2mm diameter were made by the B4C, bonded by the vinyl resin. The tracer was about ten times as large as the particle of fluidized bed material, but the traceability was enough to observe the bed-material bulk movement owing to the large effective viscosity of the fluidized bed. The visualized images indicated that the bubbles and/or wakes were important mechanism of the behavior of the fluidized bed movement.

Umekawa, H.; Ozawa, M.; Takenaka, N.; Matsubayashi, M.

1999-11-01

134

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

Microsoft Academic Search

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. ×Populus nigra L.) and red clover (Trifolium pratense L.) plants were used in an 8-week

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

2005-01-01

135

Interpretation of alluvial beds through bed-elevation distribution moments  

NASA Astrophysics Data System (ADS)

With equipment advances now enabling the measurement and processing of alluvial-bed elevation data at high spatial and temporal resolutions, the moments of measured bed-elevation distributions can be used to characterize riverbed structure. From analyses of a wide range of high-quality data sets for a range of flows, sediments, and types of bed surface (e.g., armoured gravels, uniform sands, ripples, and dunes), at laboratory and field scales, the standard deviation of bed elevations ? is found to provide a robust integral measure of bed-roughness height. This approach has the statistical advantage of utilizing all relevant bed-elevation information, and also removes any potential need to subjectively identify valid individual roughness elements within the measured bed data. In addition to ? defining the vertical roughness scale for a bed surface, the general shape of the bed surface forms or elements can be characterized by the bed-elevation distribution skewness Sk, with the distribution kurtosis Ku providing a measure of the evenness or intermittency of these elements. Based on the present analyses, a schematic Sk-Ku plane is presented to aid interpretation of the structure of steady state and developing alluvial bed surfaces from measured bed-elevation distributions, where various bed surface types (e.g., artificially smoothed beds, armoured gravel beds, planar beds of mobile uniform sediments, ripples, and dunes) can be differentiated based on this diagram. Relatively large values of Ku that can occur for a measured riverbed surface are associated with intermittent bed-roughness elements, as can arise for supply-limited dunes or widely distributed pebble clusters or bed forms on an otherwise plane bed.

Coleman, Stephen E.; Nikora, Vladimir I.; Aberle, Jochen

2011-11-01

136

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

SciTech Connect

The Red Fork sandstone was divided into the upper and lower Red Fork which are separated by a consistent marker bed. The Red Fork interval thickens markedly across the study area from 250 ft (75 m) in the northeast to over 1300 ft (400 m) in the southwest. Most of the thickening is within the lower Red Fork. The lower Red Fork is believed to have been deposited in shelf-to-basin transitional terrain. Sands were located in delta-front, submarine-channel-fill, and possible submarine-fan terrain. The upper Red Fork is believed to represent the maximum progradation of a deltaic complex. Sandstones of the lower Red Fork are sublithic to lithic arenites; the upper Red Fork is sublithic arenite. The dominant lithic fraction is mudstone fragments. The main diagenetic alterations of both the upper and lower Red Fork sandstones were destruction of primary porosity by compaction and cementation. Dissolution chiefly of mud fragments has produced well-developed secondary porosity. Clays of the lower Red Fork mainly are authigenic chlorite; clays of the upper Red Fork primarily are authigenic kaolinite. Present oil and gas production from Red Fork sandstones is most abundant from localities on the paleoshelf.

Johnson, C.L.

1984-04-01

137

Regulation of binding of phosphofructokinase to myofibrils in the red and white muscle of the barred sand bass, Paralabrax nebulifer (Serranidae).  

PubMed

The binding of phosphofructokinase (PFK) to myofibrils from the white muscle of the fish Paralabrax nebulifer (Girard, 1854) is sensitive to factors known to be allosteric regulators of PFK activity. PFK in Triton-X-100-extracted muscle remains bound to myofibrils at pH 7.0 and is fully solubilized by increasing the pH to 8.0. The curve describing the pH-dependence of PFK binding to myofibrils is similar in its steepness to pH versus activity curves of PFK at low temperature. Nucleotides are also potent modulators, preventing the association of PFK with myofibrils at concentrations between 20 and 60 mumol l-1 of ATP, ADP, MgATP or GTP, listed in order of effectiveness. PFKs in the red and white muscle extracts differ in their pH-dependence of binding to myofibrils, and their kinetic and regulatory properties (response to citrate, pH and fructose-2,6-bisphosphate). Reversible binding of PFK to myofibrils may be important in the control of glycolysis, especially in the highly glycolytic white muscle fibres. PMID:2974860

Roberts, S J; Lowery, M S; Somero, G N

1988-07-01

138

The saltations of different sized particles in aeolian sand transport  

NASA Astrophysics Data System (ADS)

Wind tunnel experiments were performed in order to investigate the effect of mixing on the aeolian transport of sands with different grain sizes. Two types of sand with different grain size distributions and an equal-mass binary mixture of these sands were used. Comparing the gradients of their measured mass flux profiles and some published profiles for mixed sand transport with those for nearly uniform sand transport, it was found that for both of these types of sand bed, the negative gradient of the mass flux profile on a log-linear plot varies with the mass averaged grain size of the sand bed according to the same power law. Hence it can be deduced that, during the aeolian transport of mixed sand beds, the mean vertical ejection speeds of different sized grains are nearly identical to that for the transport of monospecific-sized sand with the same mass averaged grain size. Theoretical analysis was undertaken to explore the characteristics of ejections of different sized grains during the aeolian transport of sand with mixed-size grains. It is proposed that the mean ejection angles and the mean ejection speeds for sand grains of different sizes are nearly identical and are equivalent to that for monospecific-sized sand with the same mass averaged grain size. It was also evident that the ratio between the transport rate of each grain size group expressed as the fraction in the whole transport rate and its mass fraction in the mixed-size sand is a combined consequence of both the wind effect on the mean saltation distance of different sized grains and the effect of the mass fraction of each grain size group in the original mixture on its ejection potential responding to an impact of a saltating sand grain.

Xing, Mao; Wu, Chuanyu; Adams, Michael J.

2011-11-01

139

Modelling sand–mud morphodynamics in the Friesche Zeegat  

Microsoft Academic Search

The objective of the study presented in this paper is to investigate the predictive capabilities of a process-based sand–mud model in a quantitative way. This recently developed sand–mud model bridges the gap between noncohesive sand models and cohesive mud models. It explicitly takes into account the interaction between these two sediment fractions and temporal and spatial bed composition changes in

Mathijs van Ledden; Zheng-Bing Wang; Han Winterwerp; Huib de Vriend

2006-01-01

140

Sand Diver  

NASA Astrophysics Data System (ADS)

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

Scott, Alan J.

2005-01-01

141

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

142

Sand resistance of sunscreens.  

PubMed

Like water resistance in sunscreens, sand resistance in sunscreens is the ability of the sunscreen to retain its effectiveness while undergoing sand treatment. The influence of the type of sand on the sand resistance of sunscreens has not been described. The sand resistance of a control standard sunscreen, P2, and data on three grades of Quickrete commercial grade sand, #1961, #1962, and #1152, are described. These sands represent a fine sand, a medium sand, and an all-purpose sand. Using the methodology described in the 2007 proposed amendment of the Final Monograph (1) with one exception, we obtained an SPF of 16.5 (1.6) for the control standard, compared to the expected SPF of 16.3 (3.4). After a five-minute treatment of sand #1961, #1962, or #1151, the SPF of the control standard was 18.3 (1.6), 18.4 (2.0), and 17.5 (2.2), respectively. Thus, all three sands exhibited a similar sand-resistance response. Thus, there was no significant difference in the average SPF with and without sand. The medium grade sand, Quickrete commercial grade #1962, was preferred for sand-resistance testing because the fine sand was difficult to remove from the subject's backs and the coarse sand was unpleasant to the subjects. PMID:23193889

Caswell, Michael; Wood, Caryl; Martinez, Alexa

143

Lizard locomotion on weak sand  

NASA Astrophysics Data System (ADS)

Terrestrial animal locomotion in the natural world can involve complex foot-ground interaction; for example, running on sand probes the solid and fluid behaviors of the medium. We study locomotion of desert-dwelling lizard Callisaurus draconoides (length 16 cm, mass=20 g) during rapid running on sand. To explore the role of foot-ground interaction on locomotion, we study the impact of flat disks ( 2 cm diameter, 10 grams) into a deep (800 particle diameters) bed of 250 ?m glass spheres of fixed volume fraction ? 0.59, and use a vertical flow of air (a fluidized bed) to change the material properties of the medium. A constant flow Q below the onset of bed fluidization weakens the solid: at fixed ? the penetration depth and time of a disk increases with increasing Q. We measure the average speed, foot impact depth, and foot contact time as a function of material strength. The animal maintains constant penetration time (30 msec) and high speed (1.4 m/sec) even when foot penetration depth varies as we manipulate material strength. The animals compensate for decreasing propulsion by increasing stride frequency.

Goldman, Daniel

2005-03-01

144

Scaling Laws in Aeolian Sand Transport  

NASA Astrophysics Data System (ADS)

We report on wind tunnel measurements on saltating particles in a turbulent boundary layer and provide evidence 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 nonerodible 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 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 a natural environment.

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

2011-03-01

145

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

Microsoft Academic Search

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

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

1994-01-01

146

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

SciTech Connect

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

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

1994-03-01

147

Gravel-Sand Transition in a Large, Lowland Alluvial Channel.  

NASA Astrophysics Data System (ADS)

The beds of alluvial river channels become finer grained moving downstream and often exhibit an abrupt transition from gravel to sand-bedded conditions. Most previous work documenting this phenomenon have focused on small upland streams where sediment supply to the channel is strongly connected to sediment delivery from hillslopes. Fewer studies have focused on the gravel-sand transition in large alluvial channels and none have documented the spatial variability through reaches where transitions occur. The downstream fining pattern observed in the Fraser River is widely cited as a classic example of an abrupt gravel-sand transition in a large alluvial channel. However, important questions regarding the exact current location of the transition, its morphology, and what controls its location remain unanswered. Here, we present detailed observations of bed material grain-size and river bed topography through the reach where the transition is widely thought to occur in the Fraser River. Bed topography was measured using a multibeam echo- sounding system (Reson 8101 Seabat) at high flow (11,000 m3s-1) when all fractions of the bed material were mobile. Some limited bed material sampling was done at high flow with more detailed sampling at low flows (~1000 m3s-1). These observations indicate that there is little gravel material on the active channel bed downstream of Yaalstrick Bar, the last bar along the river dominated by gravel (> 75% of the bar material > 2 mm). However, sorting patterns caused by the superior mobility of gravel over sand have lead to gravel patches on the upstream sides and surfaces of sand bars. There are also gravel patches along the thalweg through the apex of some river bends, but whether this is topographically induced sorting or a lag deposit exposed by high flow is not clear. Bedforms associated with sand-gravel mixtures appear on the river bed immediately downstream of Yaalstrick Bar in a sequence (sand ribbons, barchans, dunes) suggesting sand deposition from suspension. There is also a dramatic increase in bar amplitude downstream of Yaalstrick Bar, suggesting greater sand composition. Our observations suggest the gravel- sand transition in the Fraser River is somewhat more diffuse than is observed in smaller scale channels. Yet, for all practical purposes, Yaalstrick Bar is the end of the gravel-bedded reach of the Fraser River.

Venditti, J. G.; Humphies, R. P.; Allison, M. A.; Nittrouer, J. A.; Church, M.

2008-12-01

148

Sand dunes as migrating strings.  

PubMed

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

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

2013-05-24

149

Analysis of sand particles' lift-off and incident velocities in wind-blown sand flux  

NASA Astrophysics Data System (ADS)

In the research of windblown sand movement, the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle's motion to windblown sand flux. In this paper, we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of particle image velocimetry (PIV) and data processing method. And then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was analyzed. The results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles, i.e., the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution, respectively. However, it influences the center of the Gaussian distribution, the decay constant and the amplitude of the negative exponential distribution.

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

2013-04-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

153

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

154

The extraction of bitumen from western oil sands: Volume 1. 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 an executive summary and reports for five of these projects. 137 figs., 49 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

155

Taphonomic comparison between Recent and fossil sand dollars  

Microsoft Academic Search

The taphonomy of a Recent and a fossil sand dollar are compared. The recent Echinodiscus auritus originates from a shallow-water carbonate environment in the Red Sea. The fossil Parascutella höbarthi is found in micaceous sands of the Lower Miocene Austrian Molasse Zone. Both species show strong similarities in constructional morphology including the flattened overall shape, details of the surface morphology

James Nebelsick

1999-01-01

156

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

157

Sand-flat/playa mud-flat-lacustrine cycles in Fundy rift basin (Triassic-Jurassic), Nova Scotia: implications for climatic and tectonic controls  

SciTech Connect

Blomidon Formation red beds comprise over 200 m-scale cycles of (1) sand-flat sandstone (distal alluvial-fan deposits) and (2) playa sandy mudstone and/or lacustrine claystones. Rift basin subsidence and local sagging along the Glooscap fault system generated sand-flat/playa mud-flat cycles by shifting loci of active fan sedimentation toward and away from the playa surface as fan lobes migrated toward topographic lows. Episodes of intense aridity are recorded in the sand-flat and playa mud-flat deposits where amalgamated sheetflood packages are characterized by pervasive evaporite mineralization (principally gypsum) controlled by subsurface evolution of a Ca-SO/sub 4/-Na-Cl brine. Aridity is further evidenced by significant disruption of sedimentary fabrics beneath evaporite crusts, deep mud cracks, eolian sandstone layers and patches, and precipitation of authigenic calcium and magnesium-rich illite/smectite and analcime. Carbon isotopic data from early formed, low-magnesium calcite cements (pre-gypsum) reflect slightly to moderately elevated subsurface salinities that accompanied initial brine evolution. During relatively wetter periods, lacustrine platy claystones accumulated in shallow, oxidizing lakes that lapped onto the sand flats. Claystone units lack evaporite minerals and textures, and many units are partially burrowed. Carbon isotopic data from calcite cements are consistently lighter than sand-flat/playa mud-flat calcites and were in equilibrium with relatively fresh subsurface pore waters.

Mertz, K.A. Jr.; Hubert, J.F.

1989-03-01

158

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.

159

Exploring Products: Nano Sand  

NSDL National Science Digital Library

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

Network, Nanoscale I.; Sciencenter

2010-01-01

160

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

SciTech Connect

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

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

1993-07-01

161

Formation of tidal sand waves: Effects of the spring-neap cycle  

NASA Astrophysics Data System (ADS)

The effects that the spring-neap cycle has on the formation of tidal sand waves are investigated by performing a linear stability analysis of the flat bottom configuration of a shallow sea subject to a modulated tidal current. The slow temporal changes of the tidal range tend to accelerate the process which leads to the appearance of tidal sand waves and to give rise to shorter bed forms, when sediment transport is dominated by the bed load contribution. When the suspended load provides a significant contribution to the total load, the growth rate of the sand waves becomes smaller and longer bed forms tend to be generated.

Blondeaux, Paolo; Vittori, Giovanna

2010-10-01

162

High-speed x-ray tomographic imaging of a ball impacting on sand  

NASA Astrophysics Data System (ADS)

When a ball is dropped in fine, very loose sand, a cavity is formed inside the sand bed which collapses, creating a jet and entraining an air bubble. At a fixed depth below the surface, the shape and dynamics of a horizontal cross section of the cavity are studied by means of high-speed x-ray tomography system. Repeating the procedure at different depths provides a full time-resolved reconstruction of the cavity within the sand bed. Using this reconstruction we test several hypotheses on the process of sand jet formation.

Homan, Tess A. M.; Wagner, Evert C.; Mudde, Rob F.; Lohse, Detlef; van der Meer, Devaraj

2010-11-01

163

Liquid-Fluidized-Bed Heat Exchanger Flow Distribution Models.  

National Technical Information Service (NTIS)

Allied Chemical Corporation at the Idaho National Engineering Laboratory is developing liquid-fluidized-bed shell-and-tube heat exchangers for geothermal applications. Sand fluidized by geothermal water on the shell side prevents scaling and increases hea...

L. T. Cole C. A. Allen

1979-01-01

164

Benthic infauna of eelgrass, Zostera marina , beds  

Microsoft Academic Search

The infauna ofZostera beds in the Chesapeake Bay-York River estuary and Chincoteague Bay was sampled in March and July 1970 using a corer. Sediments\\u000a were fine sand or very fine sand. Sorting of sediments varied from poorly sorted to moderately well-sorted and appeared to\\u000a be positively correlated with the density ofZostera at the respective stations.\\u000a \\u000a A total of 117 macroinvertebrate

Robert J. Orth

1973-01-01

165

Laboratory measurement of electrification of wind-blown sands and simulation of its effect on sand saltation movement  

NASA Astrophysics Data System (ADS)

This article presents a measurement of electrification generated by wind-blown sands in a field wind tunnel and a numerical methodology to simulate the effect of electrification on the sand saltation movement after the mutual couple interaction between the sand movement and the wind flow is taken into account. The measured data of electric charge on the "uniform" sands in the wind-tunnel tests show that the sign of electric charge, either negative or positive, is mainly dependent on the diameter size of sand particles, i.e., negative charge is gained when the diameter is smaller than 250 ?m and positive charge is obtained if the diameter is larger than 500 ?m, and that for both "uniform" and mixed sands, the average charge-to-mass ratio decreases with increasing the wind velocity, and increases with height from sand bed. Meanwhile, the measurement of electric field in wind-sand cloud related to the electric charge displays that the magnitude of electric field increases generally as the wind velocity and the height increase, and the direction of the field is always upwardly vertical to the Earth's surface, which is opposite to that of the fair-weather field. In order to exhibit the effect of electrification on sand saltation movement, a theoretical model by considering the mutual coupling interaction between wind flow and sand movement is proposed after the electric force exerted on the moving sands is considered. Through solving the nonlinear coupling dynamic equations by a proposed program, the effect of electrification on sand saltation motion, e.g., trajectory, is discussed quantitatively. After that, its effect on wind-sand transport flux, sand ejecta flux, and wind profile is also displayed. The results show that the prediction for the Bagnold's kink is good agreement with the measurement in literature.

Zheng, Xiao Jing; Huang, Ning; Zhou, You-He

2003-05-01

166

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

167

Experimental and modeling study of residual liquid recovery from spent sand in bitumen extraction processes from oil sands.  

PubMed

Disposing solid residue with high liquid content into the environment may impact the immediate ecosystem and its surroundings. In bitumen recovery process from oil sands, it is environmentally and economically desirable to effectively recover as much of the liquid trapped in the spent solids as possible, prior to releasing it into the environment. An experiment was designed to investigate the effect of capillary force to enhance liquid recovery by using a thin, semipermeable layer as the membrane. The results indicate that by employing a membrane at the outlet, and pressurizing the air above the sand bed, the average liquid saturation can be decreased by 50%; however, the maximum pressure applied is restricted by the physical characteristics of the membrane. A mathematical model is developed to predict the liquid saturation profile along the sand pack during transient and steady-state conditions, and results are validated against measured average saturation using two different sand types. Results suggest that more liquid can be recovered from the spent sand bed by increasing the height of the bed; however, the required time to achieve the maximum recovery is increased as well. This method can be applied to reduce the liquid content of spent sand from any process before it is disposed of, thereby reducing possible hazards which may affect the environment. PMID:23293943

Faradonbeh, Moosa Rabiei; Dong, Mingzhe; Harding, Thomas G; Abedi, Jalal

2013-01-28

168

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

SciTech Connect

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

Carter, R.R.

1988-05-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

170

Macrobenthic Invertebrates in Bare Sand and Seagrass (Thalassia testudinum) at Carrie Bow Cay, Belize.  

National Technical Information Service (NTIS)

The generally accepted view that seagrasses support a more dense and diverse invertebrate fauna than sand areas devoid of such vegetation was tested in Thalassia testudinum beds of Carrie Bow Cay lagoon, Belize. Mechanisms regulating the distribution of i...

D. K. Young M. W. Young

1982-01-01

171

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

PubMed

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

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

2012-05-29

172

Water resources of Red River Parish, Louisiana  

USGS Publications Warehouse

Red River Parish is on the eastern flank of the Sabine uplift in northwestern Louisiana. The 'area is underlain by lignitic clay and sand of Paleocene and Eocene age which dip to the east at the rate of about 30 feet per mile. The Red River is entrenched in these rocks in the western part of the parish. Alternating valley filling and erosion during the Quaternary period have resulted in the present lowland with flanking terraces. In the flood-plain area moderate to large quantities of very hard, iron-bearing water, suitable for irrigation, are available to wells in the alluvial sand and gravel of Quaternary age. The aquifer ranges in thickness from 20 to slightly more than 100 feet. It is recharged by downward seepage of rainfall through overlying clay and silt, by inflow from older sands adjacent to and beneath the entrenched valley, and by infiltration from the streams where the water table is below stream level during flood stages or as a result of pumping. Water levels are highest in the middle of the valley. Ground water moves mainly toward the Red River on the east and Bayou Pierre on the west, but small amounts move down the valley. Computations based on water-level and aquifer-test data indicate that the Quaternary alluvium contains more than 330 billion gallons of ground water in storage and that the maximum discharge of ground water to the streams is slightly more than 30 mgd (million gallons per day). At times of high river stage, surface water flows into the aquifer at a rate that depends in part upon the height and duration of the river stage. Moderate supplies of soft, iron-bearing water may be obtained from dissected Pleistocene terrace deposits that flank the flood plains of the Red River and Black Lake Bayou. However, the quantity of water that can be pumped from these deposits varies widely from place to place because of differences in the areal extent and saturated thickness of the segments of the deposits; this extent and thickness are governed in turn by the amount of erosion the deposits have undergone. Beds of fine-grained lignitic sands of Tertiary age contain water of generally good quality to depths of 150 to 450 feet. The thinness and low permeability of the sands restrict their development to low-yield wells. Water from these sands in the western part of the parish, where they lie beneath the alluvial valley, is more mineralized than that from the younger Tertiary sands exposed in the east-central area. Streamflow records have been collected on the principal streams in Red River Parish since 1939. Additional spot low-flow data were obtained on several small streams originating within the parish for a study made in connection with the preparation of this report. Quality-of-water data for streams in the parish were collected on an occasional spot-sampling basis prior to and during this investigation. The largest source of surface water in the parish is the Red River, which drains approximately 63,400 square miles upstream from the parish. The Red River has an average flow of about 13,100 cfs (cubic feet per second), or about 8,500 mgd. Many of the streams that drain the upland area are not dependable sources of supply because their flows are not well sustained during dry seasons. The average annual precipitation over the parish is about 52 inches, of which about 17 inches becomes runoff; this runoff is equivalent to a continuous flow of about 1.25 cfs per square mile. Seasonal and annual runoff varies, but no significant trends have been noticed. The principal surface-water problems in the parish pertain to flood control, drainage, irrigation, and navigation. Flood problems have been alleviated considerably by the operation of Denison Dam (Lake Texoma), the completion of levees on the Red River, channel improvements on Bayou Pierre, and the completion of Wallace Lake reservoir on Cypress Bayou. There are wet lands along the Red River that would be very productive if properly drained

Newcome, Roy; Page, Leland Vernon.

1963-01-01

173

Two-stage steam gasification of waste biomass in fluidized bed at low temperature: Parametric investigations and performance optimization  

Microsoft Academic Search

Steam gasification of waste biomass has been studied in a two-stage fluidized bed reactor, which has the primary pyrolysis fluidized bed using silica sand as bed material and the secondary reforming fixed bed with catalyst. The main objectives are parametric investigation and performance improvement especially at low temperature of around 600°C using the wood chip and the pig manure compost

Xianbin Xiao; Xianliang Meng; Duc Dung Le; Takayuki Takarada

2011-01-01

174

Development and Environmental Significance of an Eolian Sand Ramp of Last-Glacial Age, Central Iran  

Microsoft Academic Search

A 25-m-thick section of mostly eolian sediment is exposed in the stream-cut flank of a sand ramp accumulated in a mountain saddle near Ardakan playa, central Iran. The well-sorted eolian sediments of the ramp contain talus beds and incipient paleosols. Morphology and bedding structures imply that southeasterly winds were primarily responsible for deposition of the eolian sand. Optical dating shows

David S. G. Thomas; Mark D. Bateman; Daryoush Mehrshahi; Sarah L. O'hara

1997-01-01

175

Advances in liquid fluidized-bed heat exchanger development  

Microsoft Academic Search

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

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

1977-01-01

176

Phosphate removal in a fluidized bed—II. Process optimization  

Microsoft Academic Search

The aggregation of fine primarily formed calcium phosphate particles with sand grains in a fluidized bed for phosphate removal was studied experimentally by means of a set-up which isolated aggregation from other processes during calcium phosphate precipitation, as well as through experiments under normal operation of the fluidized bed. The net aggregation process was described by means of a mathematical

M. M. Seckler; M. L. J. van Leeuwen; O. S. L. Bruinsma; G. M. van Rosmalen

1996-01-01

177

"Sand Boil" on Bay Bridge  

USGS Multimedia Gallery

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

2009-01-26

178

Sand dunes on the central Delmarva Peninsula, Maryland and Delaware  

USGS Publications Warehouse

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

Denny, Charles Storrow; Owens, James Patrick

1979-01-01

179

Punctuated sand transport in the lowermost Mississippi River  

NASA Astrophysics Data System (ADS)

Measurements of sand flux and water flow in the Mississippi River are presented for a portion of the system 35-50 km upstream from the head of its subaerial delta. These data are used to provide insight into how nonuniform flow conditions, present in the lower reaches of large alluvial rivers, affect the timing and magnitude of sand transport near the river outlet. Field surveys during both low and high water discharge include (1) sequential digital bathymetric maps defining mobile river bottom topography which were used to estimate bed material flux, (2) multiple water velocity profiles, and (3) multiple suspended sediment profiles collected using a point-integrated sampler. These data show that total sand transport increases by two orders of magnitude over the measured range in water discharge (11,300 to 38,400 m3 s-1). During low water discharge no sand is measured in suspension, and sand discharge via bed form migration is minimal. During high water discharge 54% of the sand discharge is measured in suspension while 46% of the sand discharge is part of bed form migration. The component of boundary shear stress associated with moving this sediment is estimated using a set of established sediment transport algorithms, and values for the total boundary shear stress are predicted by fitting logarithmic velocity functions to the measured profiles. The estimates of boundary shear stress, using measurements of suspended sand transport, bed form transport, and downstream oriented velocity profiles are internally consistent; moreover, the analyses show that boundary shear stress increases by nearly 10-fold over the measured water discharge range. We show how this increase in shear stress is consistent with backwater flow arising where the river approaches its outlet. The hydrodynamic properties of backwater flow affect the timing and magnitude of sand flux and produce punctuated sand transport through the lowermost Mississippi River. Our field data are used to evaluate the influence of this sand transport style on development of the mixed bedrock alluvial channel for the lowermost Mississippi River.

Nittrouer, Jeffrey A.; Mohrig, David; Allison, Mead

2011-12-01

180

Prediction of sand transport rates by waves and currents in the coastal zone  

Microsoft Academic Search

The predictions of a sand transport research model and Bijker's (J. Waterways, Harbours Coastal Eng. Div. ASCE 97 (WW4) (1971) 687) engineering model are compared with data obtained in wave-current conditions at three field sites. A key element in the present study is that the bed roughness at the three sites has been estimated from predictions of the sand ripple

A. G. Davies; C. Villaret

2002-01-01

181

High-speed x-ray tomographic imaging of a ball impacting on sand  

Microsoft Academic Search

When a ball is dropped in fine, very loose sand, a cavity is formed inside the sand bed which collapses, creating a jet and entraining an air bubble. At a fixed depth below the surface, the shape and dynamics of a horizontal cross section of the cavity are studied by means of high-speed x-ray tomography system. Repeating the procedure at

Tess A. M. Homan; Evert C. Wagner; Rob F. Mudde; Detlef Lohse; Devaraj van der Meer

2010-01-01

182

Coalescence of emulsified wastes by fibrous bed  

Microsoft Academic Search

The feasibility of using a fibrous bed coalescer to separate emulsified oil from industrial waste streams was studied using a coalescer unit with an inside dimension of six inches. Coalescing media used included polyester, polypropylene, glass mats, sand and glass wool. Significance of wetting property was studied. Four types of oily wastes were tested under similar conditions to determine the

J. N. Chieu; R. S. Schechter; M. J. Humenick; E. F. Gloyna

1975-01-01

183

Bed Bugs FAQs  

MedlinePLUS

... to... Añadir en... Favorites Delicious Digg Google Bookmarks Bed Bugs FAQs On this Page What are bed bugs? ... are bed bugs treated and prevented? What are bed bugs? Bed bugs ( Cimex lectularius ) are small, flat, parasitic ...

184

LONG TERM RECHARGE OF TRICKLING FILTER EFFLUENT INTO SAND  

EPA Science Inventory

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

185

Steady-State Model of Wind-Blown Sand Transport.  

National Technical Information Service (NTIS)

A model for steady-state eolian saltation is presented in which computation of sand grain trajectories in the wind and of the wind velocity profile modified by saltating grain drag forces is combined with experimental data on grain-bed collisions in an it...

B. T. Werner

1990-01-01

186

Pattern dynamics of sand ripples with a tilted drive  

Microsoft Academic Search

When a sand bed is subjected to an oscillatory water flow, vortex ripples perpendicular to the flow are created. The formation of normal ripple patterns is driven by the 'separation zones' created in the troughs between ripples. The wavelength of the ripples is roughly proportional to the amplitude of the fluid motion and is independent of the frequency. Previous experiments

F. Bundgaard; C. Ellegaard; K. Scheibye; T. Bohr

2002-01-01

187

Sand pack-aided formation sand consolidation  

Microsoft Academic Search

In treating a cased and perforated well to prevent sand inflow, a resin solution from which self-curing epoxy resin is subsequently precipitated is injected into the reservoir and the perforated interval of the casing is filled with grains suspended in and permeated with the resin solution. The resin is allowed to precipitate and cure in the casing and reservoir and

Pramann

1973-01-01

188

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

189

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

190

Extreme 13Ccarb enrichment in ca. 2.0 Ga magnesite-stromatolite-dolomite-`red beds' association in a global context: a case for the world-wide signal enhanced by a local environment  

NASA Astrophysics Data System (ADS)

The Palaeoproterozoic positive excursion of ? 13Ccarb is now considered as three positive shifts of ? 13Ccarb separated by returns to 0‰, which all occurred between 2.40 and 2.06 Ma. This isotopic event is unique in terms of both duration (>300 Ma) and 13C enrichment (up to +18‰). The mechanism responsible for one of the most significant carbon isotopic shifts in Earth history remains highly debatable. To date, ? 13C of +10‰ to +15‰ cannot be balanced by organic carbon burial ( forg) as there is no geological evidence for an enhanced C org accumulation prior to or synchronous with the excursion. Instead, termination of these excursions is followed by formation of a vast reservoir of 13C-depleted organic material (-45‰ at Shunga) and by one of the earliest known oil-generation episodes at 2.0 Ga. None of the three positive excursions of ? 13Ccarb is followed by a negative isotopic shift significantly below 0‰, as has always been observed in younger isotopic events, reflecting an overturn of a major marine carbon reservoirs. This may indicate that forg was constant: implying that the mechanism involved in the production of C org was different. Onset of intensive methane cycling resulting in ?c change is another possibility. The majority of sampled 13Ccarb-rich localities represents shallow-water stromatolitic dolostones, `red beds' and evaporites formed in restricted intracratonic basins, and may not reflect global ? 13Ccarb values. Closely spaced drill core samples ( n=73) of stromatolitic dolostones from the >1980±27 Ma Tulomozerskaya Formation in the Onega palaeobasin, Russian Karelia, have been analysed for ? 13Ccarb and ? 18Ocarb in order to demonstrate that different processes were involved in the formation of 13Ccarb-rich carbonates. The 800 m-thick magnesite-stromatolite-dolomite-`red beds' succession formed in a complex combination of environments on the Karelian craton: peritidal shallow marine, low-energy protected bights, barred basins, evaporative ephemeral ponds, coastal sabkhas and playa lakes. The carbonate rocks exhibit extreme 13C enrichment with ? 13C values ranging from +5.7 to +17.2‰ vs. V-PDB (mean+9.9±2.3‰) and ? 18O from 18.6 to 26.0‰ vs. V-SMOW (mean 22.0±1.6‰). The Tulomozerskaya isotopic excursion is characteristic of the global 2.4-2.06 Ga positive shifts of carbonate 13C/ 12C, although it reveals the greatest enrichment in 13C known from this interval. An external basin(s) is considered to have provided an enhanced C org burial and global seawater enrichment in 13C: the global background value for the isotopic shift at Tulomozero time (ca. 2.0 Ga) is roughly estimated at around +5‰. An explosion of stromatolite-forming microbial communities in shallow-water basins, evaporative and partly restricted environments, high bioproductivity, enhanced uptake of 12C, and pene-contemporaneous recycling of organic material in cyanobacterial mats with the production and consequent loss of CO 2 (and CH 4?) are believed to be additional local factors which may have enhanced ? 13C from +5‰ up to +17‰. Such factors should be taken into account when interpreting carbon isotopic data and attempting to discriminate between the local enrichment in 13C and globally enhanced ? 13C values. We propose that many previously reported ? 13C values from other localities, where environmental interpretations are not available or have not been taken into account may not represent the global ? 13C values.

Melezhik, Victor A.; Fallick, Anthony E.; Medvedev, Pavel V.; Makarikhin, Vladimir V.

1999-12-01

191

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

192

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

2011-05-30

193

Basaltic island sand provenance  

SciTech Connect

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

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

1992-01-01

194

Sand Ripples and Dunes  

NASA Astrophysics Data System (ADS)

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

Charru, François; Andreotti, Bruno; Claudin, Philippe

2013-01-01

195

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.

2012-06-26

196

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

197

Magic Sand Movie  

NSDL National Science Digital Library

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

2013-07-03

198

Fluidized bed incineration of a slurry waste from caprolactam production  

SciTech Connect

Caprolactam tails are a slurry waste produced in the SNIA process for the synthesis of caprolactam. They contain about 65% water, 25% ash and 10% combustible matter. The ashes are low melting, due to the presence of sodium compounds. The incineration of this waste is carried out at temperatures below 600/sup 0/C in beds of silica sand, using a laboratory scale apparatus with a 40 mm ID fluidization column. Variables investigated include sand particle size, slurry flow rate, bed temperature, bed height. The concentrations of CO/sub 2/ and CO are determined continuously in the flue gases. Bed solids are sampled periodically to determine the carbon content. Results of experiments show that the low temperature incineration on a bed of inert solids is a useful technique for the disposal of caprolactam tails. 8 refs.

Cammarota, A.; D'Amore, M.; Donsi, G.; Massimilla, L.

1980-08-01

199

Flow fields, bed shear stresses, and suspended bed sediment dynamics in bifurcations of a large river  

NASA Astrophysics Data System (ADS)

Channel bifurcations associated with bars and islands are important nodes in braided rivers and may control flow partitioning and thus affect downstream confluences, as well as the formation and dynamics of bars. However, the morphodynamic processes associated with bar formation are poorly understood, and previous studies have largely concerned laboratory experiments, small natural streams, or numerical analyses with large Froude numbers, high slopes, and low Shields stresses. In these cases, the morphologic changes at bifurcations are relatively rapid, with predominant bed load transport and the suspended load playing a minor role. In this paper, the evolution of the flow structure and suspended bed sediment transport along four expansion-diffluence units in the Rio Paraná, Argentina, are described. The Rio Paraná is a large multichannel river with a bed composed of medium and fine sands and possesses low Froude numbers and high suspended bed material transport. Primary and secondary flow velocity components were measured with an acoustic Doppler current profiler (ADCP) along the expansion-diffluence units, and the backscatter signal of the ADCP was calibrated to allow simultaneous measurements of suspended bed sediment concentrations. The interactions between these variables show that the cores of primary flow velocity and suspended bed sediment concentration do not necessarily follow the thalweg at the bifurcation and that inertial effects on the suspended bed sediment may influence the morphodynamics of bar formation. It is suggested that changes in flow stage, as well as the presence of vegetation, may further increase the deposition of suspended bed sediment at the bar head. This study suggests that the ratio of suspended bed material to bed load is an important factor controlling the morphodynamics of bifurcations in large sand bed braided rivers.

Szupiany, R. N.; Amsler, M. L.; Hernandez, J.; Parsons, D. R.; Best, J. L.; Fornari, E.; Trento, A.

2012-11-01

200

Detection of the bottom facies characteristics at El Zeit Bay, Red Sea, by using a single-beam acoustic sound  

NASA Astrophysics Data System (ADS)

El Zeit Bay is a semi-closed area with a rectangular shape which south side is connected witu northwestern side of Red Sea. The study was done to detect the characteristics of the bottom facies at El Zeit Bay. Single-beam seabed echoes combined with diving survey and sediments analyses were used to detect sea bed characteristics. The seabed floor of the study area is characterized by three physiographical distinct bottom facies; sand facies: floral facies and coral patches facies. Sand facies lies at very shallow water it extended from shore line to depth about 2 m. It has very fine sand size intercalated by mud sediments. It is characterized by very poor benthos. Floral bottom facies has medium sand which characterized by rich floral vegetation this flora appear in scattered and irregular forms. It is observed at an average depth from 4 m to 6 m. Coral patches facies is characterized by the presence of coarse sediments. The coral reef covers about 40% of the study area (29.5% hard corals and 10.5% is soft ones) while the rest of the area (60%) is characterized by different benthos. In communities general, his area characterized by high biodiversity.

Hamouda, Amr Z.; El-Wahhab, Mahamed Abd

2012-02-01

201

Pheromonal Control of Metamorphosis in the Pacific Sand Dollar, Dendraster excentricus.  

PubMed

Competent larvae are induced to undergo metamorphosis by sand from a sand dollar bed or an aqueous extract of the sand. Gel permeation chromatography and high-performance liquid chromatography of the extract yielded a 980-dalton peptide that will induce metamorphosis between 10(-6) and 10(-5) molar. Extracts of whole adults and gonads were also able to induce metamorphosis, and adults can condition substrates to induce metamorphosis. Therefore, the initiation of metamorphosis in Dendraster excentricus is controlled by a pheromone released by adult sand dollars. PMID:17813263

Burke, R D

1984-07-27

202

City-swallowing Sand Dunes  

NSDL National Science Digital Library

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

Bell, Trudy E.

2007-06-19

203

Experiment Investigation of the Influencing Factors on Bed Agglomeration During Fluidized-Bed Gasification of Biomass Fuels  

NASA Astrophysics Data System (ADS)

With the depleting of fossil fuel and environmental polluting increasing, the utilization of biomass resources caught increasing concern. Biomass gasification in fluidized bed, as one promising technology, developed quickly. However, serious agglomeration was displayed as biomass ash reacted with bed material (silica sand) at higher temperature. It hindered the wide utilization of CFB gasifier. The objective ofthis work is to investigate the agglomeration behavior between biomass ash and silica sand, and catch the inherent mechanism. Firstly, the influence of ash compounds on the agglomeration behavior was analyzed with biomass ash and synthesis ash compounds addition in fixed bed as ash sample mixed with bed material evenly before every trial. The reaction temperature was set 850°C that is the operated temperature for many fluidized bed gasificated biomass fuels. Then the influence of reaction time was analyzed. The characteristics of the agglomerated silica sand particles were analyzed by the XRD. Finally, it was simulated with HSC computer mode based on thermodynamic equilibrium. It was observed that when the ratio of the biomass ash to the silica sand was above 0.2, the agglomeration was observed. With the increase of the reaction time, more silica sand particles agglomerated with the biomass ash. There are two kinds of silicate eutecticum investigated by the XRD. It is of great significance for the running ofCFB biomass gasifier and the development ofbiomass utilization technology.

Chen, Y. Q.; Chen, H. P.; Yang, H. P.; Wang, X. H.; Zhang, S. H.

204

The extraction of bitumen from western tar sands  

SciTech Connect

This report represents the work done during the year of May 8, 1987 to June 9, 1988. This year was the first year of a five-year program. The overall objective of the latter is to advance the technologies for recovering bitumen from the tar sands by thermal and water assisted extraction means and upgrading of bitumen to synthetic crude, and conversion of bitumens to specialty products such as asphalt and resins to levels where realistic evaluations of technical and commercial potential can be made. Additionally, it is desired to have the data at a level which is adequate for design of pilot plants of appropriate size deemed necessary for commercial scale-up of the various processes being studied. The main areas for studies covered in this report are modelling and optimization of the hydropyrolysis process for upgrading bitumens, bitumen recovery by pyrolysis of the circle Cliffs tar sands in a fluid bed, pyrolysis of Whiterocks tar sand in a rotary kiln, modelling of the combustor in the coupled fluidized bed with interbed heat transfer using heat pipes, development of superior diluents for use in the water extraction of Utah's tar sands, and fractionation and characterization of the bitumens from Asphalt Ridge and Sunnyside tar sands. 169 refs., 60 figs., 31 tars.

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

1989-05-01

205

Sand-box experiment to investigate incremental and finite strain  

NSDL National Science Digital Library

100 level students, in groups of 3-6, are provided with small sand-boxes fitted with a single moving end. Each box is filled with different colored layers of sand, grit, and ploymer grains to simulate bedding. Students progressivley shorten the layered section and record various parameters at each stage. Students then plot this data graphically and report back on the evolution of the structure (usually a fold), including it's geometry, scale, orientation, etc. This exercise is designed to encourage patient, careful analogue experimentation and data-recording; a successful exercise is assessed by detailed records and integration of different parameters towards a narrative of the deformation.

Graham Andrews, California S.

206

Predicted and observed cyclic performance of piles in calcareous sand  

SciTech Connect

The performance of small-scale model piles jacked into calcareous sand and tested under cyclic axial loadings is presented in this paper. The calcareous sand beds used for the tests have been prepared from reconstituted soil that has been consolidated under different overburden pressures using a test vessel of special design. The study is focused on the accumulation of permanent displacement of the piles under both uniform and nonuniform amplitude cyclic loadings. A numerical analysis is employed to predict the cyclic behavior of the model piles, using input parameters derived from the experimental results. Comparisons between the measured and predicted results show reasonable agreement.

Al-Douri, R.H.; Poulos, H.G. (Univ. of Sydney (Australia))

1995-01-01

207

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.

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

2013-01-01

208

Articulated bed  

US Patent & Trademark Office Database

A bed arrangement (10) has an articulated mattress support (30), a support frame (40) for the articulated mattress support, and a power assembly (50) for raising and lowering flexible sections (30b, 30c, 30d) of the articulated mattress support. The support frame (40) is adjustably mounted in a stationary outer frame (20) and has a size smaller than the articulated mattress support (30). The power assembly (50) is mounted on the support frame (40).

Eriksson; Rikard (Tibro, SE); Johansson; Mikael (Tibro, SE)

2009-02-03

209

Study of Wood Pyrolysis and Gasification by Thermogravimetry and in a Catalyst Fluidized Bed.  

National Technical Information Service (NTIS)

A study of wood wastes pyrolysis and vapor gasification kinetics is presented together with a study of the implementation of sawdust vapor gasification in fluidized beds with sand, activated alumina and a Nickel/alumina catalyst. Based on thermogravimetri...

M. Hemati

1984-01-01

210

An experimental study of fluidized-bed coating: influence of operating conditions on growth rate and mechanism  

Microsoft Academic Search

This study investigates the influence of fluidizing gas velocity, atomizing air, and liquid flow rates, liquid concentration, initial bed mass, and particle size on the mechanism of growth of sand particles in a batch fluidized-bed coater. An aqueous solution of NaCl was used as the coating liquid and sprayed in the bed by means of a pneumatic atomizer. The results

K. Saleh; R. Cherif; M. Hemati

1999-01-01

211

Deep bed filter as pre-treatment to stormwater  

Microsoft Academic Search

This paper presents the results of experiments on the application of dual media and single media deep bed filters as pre-treatments to stormwater. In-line flocculation-filtration experiments were conducted with dual and single media filter. The single filter media (80 cm) consisted of either anthracite or sand, and the dual media filter consisted of sand (40 cm at the bottom) and

M. A. H. Johir; S. Vigneswaran; J. Kandasamy

2009-01-01

212

Petrographic, stratigraphic, and structural study of the Smackover gray sand (Jurassic) in north Louisiana  

SciTech Connect

The gas-producing gray sand, a dark gray to black, very fine-grained sand, occurs as 3 sand tongues in the lower member of the Smackover Formation in the subsurface of Bossier, Webster, Claiborne, and Lincoln parishes, Louisiana. A Flaser-bedded silty shale facies indicates deposition on a mid-tidal flat environment. Smackover deposition during the Jurassic in the study area was located on the gently dipping slope between a broad coastal shelf to the north and a basin to the south. The gray sand was deposited over the Norphlet formation and Louann salt before flowage and swelling of the Louann salt began. Uplift and swelling of the Louann salt later in the Jurassic created growing anticlines; sediment slumped off the structural highs of the growing salt anticlines into basinal muds and silts. The Smackover gray sand continues to challenge exploration geologists because of the lateral pinch out of its sand tongues. 11 references.

Miciotto, S.A.

1980-01-01

213

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

214

Sand Penetration Experiments  

NASA Astrophysics Data System (ADS)

In an experimental program, steel bullets and short cylinders, and tungsten alloy rods were shot into dry silica sand at 600 to 1100 m/s. The rods included finsets that were designed for aerodynamic stabilization. The fins also apparently provided trajectory stabilization within the sand as well. Time-of-arrival screens allowed measurement of velocity. Analysis of those data indicated that drag coefficients increased as projectiles slowed down. Comparison with previous data indicates there was a slight increase in drag coefficient of rods over expected values for unfinned rods; however, the net result was penetration normalized by length was as high as 40, depending on nose shape. It was found that when the velocity exceeded about 80 m/s (which is close to the speed of sound in sand) sand particles were broken down into their constituent grains, resulting in a decrease in size by about 1000. Normalized penetration is expected to scale as kinetic energy per unit area, and it was significantly higher for the rods than for the other projectiles. This is attributed to stabilization from interaction of the fins with the cavity wall.

Bless, Stephan; Berry, Don; Lawhorn, William

2009-06-01

215

Petrocalcic paleosols, Hensel (Gillespie) Sand, Gillespie County, Texas  

SciTech Connect

Paleocalcretes are common in all sediment types of the Hensel Sand in Gillespie County, Texas. Calcretes in mudstone are nodular, grading from rhizoconcretions to total replacement. In sandstone the paleosols tend to form undulating hardpans having cracked upper surfaces. Massive calcretes in basal conglomerates have greatly reduced the original permeability, restricting groundwater flow. Hensel Sand overlies upper Precambrian to Middle Pennsylvanian rocks; displacive crystallization of the calcitic globules and fibers was able to lift and displace 1m2 to 2m2 blocks of flaggy Upper Cambrian limestone in to spectacular teepee structures. Gillespie Sand is that portion of the basal Cretaceous Hensel Sand that stratigraphically overlies the middle Glen Rose Salenia/Corbula beds', and underlies upper Glen Rose or basal Fredericksburg rocks. It formed as non-marine valley fill during prolonged, episodic marine transgression. This study documents ubiquitous calcrete development in Central Texas during the lower part of the Middle Albian State; calcretes are now known from the Lower Aptian (Sycamore Sand) through the Middle Albian (Paluxy and upper Antlers Sands). A seasonal arid to semi-arid climate is indicated for at least 5 million years.

Wolff, E.C. (Raba-Kistner Consultants, Inc., San Antonio, TX (United States)); Jones, J.O. (Univ. of Texas, San Antonio, TX (United States). Geology Dept.); Amsbury, D.L.

1993-02-01

216

Substrate preference in age-0 red snapper, Lutjanus campechanus  

Microsoft Academic Search

We tested age-0 red snapper, Lutjanus campechanus, for sand or shell substrate preference in a circular tank (1.5 m diameter × 0.6 m deep). The test tank was divided into two equal areas of whole oyster shell or sand substrates. All trials were video taped for 20 to 25 min. Tapes were viewed on a monitor and locations of all

Stephen T. Szedlmayer; Jeffrey C. Howe

1997-01-01

217

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

218

Grain size dependency in the occurrence of sand waves  

NASA Astrophysics Data System (ADS)

Sandy shallow seas, like the North Sea, are very dynamic. Several morphological features are present on the bed, from small ripples to sand waves and large tidal sandbanks. The larger patterns induce significant depth variations that have an impact on human activities taking place in this area. Therefore, it is important to know where these large-scale features occur, what their natural behaviour is and how they interact with human activities. Here, we extend earlier research that compares the results of an idealized model of large-scale seabed patterns with data of seabed patterns in the North Sea. The idealized model is extended with a grain size dependency. The adaptations lead to more accurate predictions of the occurrence of large-scale bed forms in the North Sea. Therefore, grain size dependency and, in particular, critical shear stress are important to explain the occurrence of sand waves and sandbanks in the North Sea.

van der Veen, Hennie Henriët; Hulscher, Suzanne Jacqueline Marie Hélène; Knaapen, Michiel Adrianus Frederik

2006-07-01

219

Evaluation of low-cost potting mixes for bedding plants and vegetable seedlings  

Microsoft Academic Search

Low-cost potting mixes containing sawdust, Nitrolime, and Floranid were evaluated as possible growing media for bedding plants and vegetable seedlings. Plants of all varieties grown in peat\\/sand media consistently performed better than those grown in peat\\/sand\\/sawdust. Nitrogen immobilisation in the sawdust-based medium was probably the reason for the reduced growth. The peat\\/sand\\/Osmocote combination was significantly better than any other medium\\/fertiliser

M. B. Thomas; M. R. Oates; M. I. Spurway

1980-01-01

220

Liquid-fluidized-bed heat exchanger flow distribution models  

Microsoft Academic Search

Liquid-fluidized-bed shell-and-tube heat exchangers for geothermal applications are considered. Sand fluidized by geothermal water on the shell side prevents scaling and increases heat transfer coefficients over conventional heat exchangers. Tests conducted on two instrumented fluidized-bed heat exchanger models, constructed primarily of plexiglass, which differ in tube bundle orientation are described. Plexiglass construction allowed visual observation of flow patterns. The vertical

L. T. Cole; C. A. Allen

1979-01-01

221

Gasification of corn stover in a fluidized bed  

Microsoft Academic Search

Dried corn stover was gasified in a series of test runs at 840 to 1020 K in a 22.9 cm I.D. fluid bed gasifier. The field residue was prepared for gasification by size reduction in a hammer mill to pass a 0.64 cm screen and subsequently dried to 7% moisture. The bulk of the bed was composed of silica sand

K. P. Raman; W. P. Walawender; Y. Shimizu; L. T. Fan

1981-01-01

222

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

Microsoft Academic Search

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

T. L. Crawford

1986-01-01

223

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

224

PROCESSING OF MONAZITE SAND  

DOEpatents

A process for the recovery of thorium, uranium, and rare earths from monazite sands is presented. The sands are first digested and dissolved in concentrated NaOH, and the solution is then diluted causing precipitation of uranium, thorium and rare earth hydroxides. The precipitate is collected and dissolved in HCl, and the pH of this solution is adjusted to about 6, precipitating the hydroxides of thorium and uranium but leaving the rare earths in solution. The rare earths are then separated from the solution by precipitation at a still higher pH. The thorium and uranium containing precipitate is redissolved in HNO/sub 3/ and the two elements are separated by extraction into tributyl phosphate and back extraction with a weakly acidic solution to remove the thorium.

Calkins, G.D.; Bohlmann, E.G.

1957-12-01

225

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

226

White Sands Test Facility  

NASA Astrophysics Data System (ADS)

This is an overview of the White Sands Test Facility's role in ensuring the safety and reliability of materials and hardware slated for launch aboard the Space Shuttle. Engine firings, orbital flights debris impact tests, and propulsion tests are featured as well as illustrating how they provide flight safety testing for the Johnson Space Center, other NASA centers, and various government agencies. It also contains a historical perspective and highlights of major programs that have been participated in as part of NASA.

227

Grain size and transport characteristics of non-uniform sand in aeolian saltation  

Microsoft Academic Search

Size frequency distributions of sediment particles in a wind tunnel containing a bed of non-uniform sand are investigated by re-interpreting existing experimental data using particle-size analysis. Each particle sample is classified into one of eight groups according to its size grading. The analysis reveals that the modal shape of the particle-size frequency distributions of the saltating sand at different elevations

Z. S. Li; D. J. Feng; S. L. Wu; A. G. L. Borthwick; J. R. Ni

2008-01-01

228

Practice Hospital Bed Safety  

MedlinePLUS

... Hospital Bed Fires [ARCHIVED] A Guide to Bed Safety Bed Rails in Hospitals, Nursing Homes and Home Health Care: The Facts (PDF Version) (PDF - 65KB) MedWatch: The FDA Safety Information and Adverse Event Reporting Program - Page Last ...

229

Red Bull  

Microsoft Academic Search

The Red Bull case describes the history of the Red Bull brand and how the company stimulated and harnessed word-of-mouth to build a new product category (functional energy drinks) and brand franchise. The case concludes by asking the reader to consider how Red Bull should react to competitive challenges in the U.S. The Red Bull case was written to enable

Paul Farris; Richard Johnson

230

Booming Sand Dunes  

NASA Astrophysics Data System (ADS)

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

Vriend, Nathalie

231

Flaser and wavy bedding in ephemeral streams: a modern and an ancient example  

Microsoft Academic Search

Flaser and wavy bedding are sedimentary structures characterized by alternating rippled sand and mud layers. These structures often are considered to form mostly in tidally influenced environments; published examples from fluvial environments are rare. Flaser and wavy bedding were found in two ephemeral stream deposits: the Jurassic Kayenta Formation and the modern wash in Seven Mile Canyon, both located in

A. J Martin

2000-01-01

232

Catalytic pyrolysis of woody biomass in a fluidized bed reactor: Influence of the zeolite structure  

Microsoft Academic Search

Catalytic pyrolysis of biomass from pine wood was carried out in a fluidized bed reactor at 450°C. Different structures of acidic zeolite catalysts were used as bed material in the reactor. Proton forms of Beta, Y, ZSM-5, and Mordenite were tested as catalysts in the pyrolysis of pine, while quartz sand was used as a reference material in the non-catalytic

A. Aho; N. Kumar; K. Eränen; T. Salmi; M. Hupa; D. Yu. Murzin

2008-01-01

233

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

234

Retention of Airborne Particles in Granular Bed Filters.  

National Technical Information Service (NTIS)

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

L. Stroem

1981-01-01

235

Static holdup in Gas – Flowing solids – Fixed bed contactors  

Microsoft Academic Search

Static holdup was investigated experimentally and theoretically in gas – flowing solids – fixed bed bench-scale contactors. Diverse packing elements were used: Raschig rings, ceramic beads, crushed stone and glass beads. Four different flowing solids particles were examined: sand, propant, alumina and glass. A wide range of solid fluxes and gas velocities were used in this study.The experimental results showed

Nikola M. Nika?evi?; Zlatica J. Predojevi?; Dragan Lj. Petrovi?; Aleksandar Dudukovi?

2009-01-01

236

Pressure Fluctuations as a Diagnostic Tool for Fluidized Beds.  

National Technical Information Service (NTIS)

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

R. C. Brown J. R. Schroeder

1997-01-01

237

Heavy metal removal from wastewater in fluidized bed reactor  

Microsoft Academic Search

An innovative process for removing heavy metals including Cu, Ni and Zn from industrial wastewater has been developed. The new technology was based on inducing the nucleated precipitation of heavy metals on the sand surface in a fluidized bed reactor. The results showed that pH had a great effect on heavy metal removal efficiency and the optimum pH was about

Ping Zhou; Ju-Chang Huang; Alfred W. F Li; Shirly Wei

1999-01-01

238

Gasification of solid waste in dual fluidized-bed reactors  

Microsoft Academic Search

A solid waste treatment process has been developed in Japan which involves circulating sand particles between 2 fluidized bed reactors. A continuous pilot test of the process has been conducted since 1974. A demonstration plant has also been constructed and has operated successfully since 1976 disposing of sludge from a pulp and paper mill, municipal wastes, plastics, and tires. The

M. Kagayama; M. Igarashi; M. Hasegawa; J. Fukuda; D. Kunii

1980-01-01

239

Experimental study and modeling of fluidized bed coating and agglomeration  

Microsoft Academic Search

This work deals with the fluidized bed coating and agglomeration of solid particles. The effect of particle size on coating criteria was investigated using sand particles as the coating support and aqueous solutions containing NaCl as coating liquid. The results showed that both growth rate and efficiency increase with decreasing the particle size. The growth was mainly governed by layering

K. Saleh; D. Steinmetz; M. Hemati

2003-01-01

240

Multiple dust sources in the Sahara Desert: The importance of sand dunes  

NASA Astrophysics Data System (ADS)

We determine the current sources of dust in the Sahara Desert using quantitative correlation between the number of days with dust storms (NDS), derived from remote-sensing data of high temporal resolution, with the distribution of the soil types and geomorphic units. During 2006-8 the source of over 90% of the NDS was found to be sand dunes, leptosols, calcisols, arenosols, and rock debris. In contrast to previous studies, only few dust storms originated from playas and dry lake beds. Land erodibility was estimated by regressing the NDS to the number of days with high-speed wind events, and was found to be high for sand dunes. Clay and fine-silt grains and aggregates are scarce in sand dunes, which most likely produce dust particles through aeolian abrasion of sand grains. Thus, saltating sand grains impacting clay aggregates on playa surfaces cannot be the sole process for generating dust in the Sahara.

Crouvi, Onn; Schepanski, Kerstin; Amit, Rivka; Gillespie, Alan R.; Enzel, Yehouda

2012-07-01

241

Recovery and upgrading of oil from Utah tar sands: Final report  

Microsoft Academic Search

The main areas for study in this report are bitumen upgrading by hydropyrolysis, a low coke-producing process pioneered at the University; bitumen recovery by pyrolysis of tar sand in a fluidized-bed retort; bitumen recovery in coupled fluidized-beds with interbed heat transfer via heat pipes; and bitumen recovery by water-assisted separation methods of bitumen from ore. The principal reactions occurring in

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

1987-01-01

242

Pyrolysis of sunnyside (Utah) tar sand: Characterization of volatile compound evolution  

SciTech Connect

Tar sand is defined as any sand or rock which is impregnated with heavy oil or bitumen. (This excludes coal, oil shale, and Gilsonite). In the United States alone, there are an estimated 60 billion barrels of bitumen in tar sand, some of which is recoverable. The Sunnyside deposit in Utah accounts for approximately 4.4 billion barrels of recoverable bitumen, making it an attractive deposit for recovery processing. Several commercial concerns have had financial interest in the development of recovery processing, including in-situ thermal (Shell Oil), steam flooding (Signal Oil and Gas), and solvent extraction (AMOCO). Laboratory pyrolysis of a given tar sand is useful in pyrolysis type recovery research, both in-situ and surface. Several laboratory studies have been performed on Sunnyside tar sand, to elucidate its performance - fluidized-bed and fixed-bed pyrolysis, hydropryolysis, hot water and solvent extraction. This paper summarizes the authors' initial efforts in the laboratory pyrolysis of Sunnyside tar sand, and compares the results to the pyrolysis of other domestic tar sands (Asphalt Ridge from Utah and Big Clifty from Kentucky) studied under the same conditions.

Reynolds, J.G.; Crawford, R.W.

1988-06-01

243

Effect of scallop shells and sediment grain size on phytoplankton flux to the bed  

NASA Astrophysics Data System (ADS)

A flume study was made of bed skin friction and phytoplankton ( Thalassiosira weissf ogii) deposition about a sea scallop ( Placopecten magellanicus) mimic on a coarse (mean grain dia. =1200 ?m), medium (615 ?m) and fine (170 ?m) quarry sand. Bed skin friction immediately upstream, and at one shell diameter downstream of the mimic was 1.2-2.4 times higher than ambient values (8.1 × 10 -2 Pa). Directly downstream of the mimic there was a region of near-zero skin friction. Bed diatom density was correlated with changes in skin friction; after 21 h, cell densities were 36-87% greater in the regions of high skin friction upstream and downstream of scallop than in control experiments. The pattern of bed diatom density about the scallop was similar in the coarse and medium sands, but deposition to the fine bed was not affected by the mimic. Diatom density was significantly correlated with grain diameter; deposition in the coarse bed was 2.3 times higher than in the medium sand, and 7.4 times higher than in the fine sand. A field experiment confirmed that the coarse sand was a greater sink of phytoplankton pigment than the fine sand. Previous studies and scaling arguments suggest that the differences in bed diatom density were controlled by the magnitude of interfacial solute fluxes. Regions of high skin friction about the mimic increased the porewater exchange, resulting in greater concentrations of diatoms retained within the bed. Similarly, the more permeable coarse sand would have a greater rate of porewater exchange than the fine sand, explaining the higher bed diatom density. Differences in the predicted volume of interstitial void space as a function of grain size closely matched the observed differences in bed diatom density. Results suggest that alteration of boundary layer flows by centimetre scale topography such as scallops, increases the flux of particulate organic matter toward the bed, but whether it is retained within the bed, and thus made available to the benthos is dependent on the sediment granularity.

Pilditch, C. A.; Emerson, C. W.; Grant, J.

1997-12-01

244

Sand dollar sites orogenesis  

NASA Astrophysics Data System (ADS)

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

Amos, Dee

2013-04-01

245

Emissio nperformanc ean dcombustio nefficienc yo fa conical fluidized-bed combustor firing various biomass fuels  

Microsoft Academic Search

This paper summarizes the results of an experimental study on combustion of three distinct biomass fuels (sawdust, rice husk and pre-dried sugar cane bagasse) in a single fluidized-bed combustor (FBC) with a conical bed using silica sand as the inert bed ma- terial. Temperature, CO, NO and O2 concentrations along the combustor height as well as in flue (stack) gas

W. Permchar

246

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

247

Effects of stratification in a fluidized bed bioreactor during treatment of metalworking wastewater  

SciTech Connect

During wastewater treatment, biofilm-coated sand particles stratified in a fluidized bed bioreactor (FBB); particles coated by thicker biofilm segregated toward the top of the bed. Stratification was so well developed that at least two co-existing regions of significantly different mean biofilm thickness were visually distinct within the operating FBB. The observed stratification is attributed to differences in forces of drag, buoyancy, shear, and collisional impact, as well as differences of collision rate within the different regions. Particles with thick biofilm near the top of the bed consumed substrate at significantly lower rates per unit biomass than particles with thin biofilm near the bottom of the bed, thereby suggesting that substrate mass-transfer resistance through biofilm may limit biodegradation rates in the upper portion of the FBB. Large agglomerates of biomass floc and sand, which formed at the top of the fluidized bed, and sand particles with thick biofilm were susceptible to washout from the FBB, causing operational and treatment instability. Radial injection of supplemental liquid feed near the top of the bed increased shear and mixing, thereby preventing formation and washout of agglomerates and thickly coated sand particles. Supplemental liquid injection caused the mean specific biomass loading on the sand to increase and also increased the total biomass inventory in the FBB. Rates of biodegradation in the FBB appeared to be limited by penetration of substrates into the biofilm and absorption of oxygen from air into the wastewater.

Schreyer, H.B.; Coughlin, R.W. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemical Engineering

1999-04-20

248

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...

249

Well sand packing prevention method  

SciTech Connect

A method is described of preventing sand packing in a producing well completed in a zone adjacent a hydrocarbon-bearing subterranean formation, comprising the steps of: producing fluid from the hydrocarbon-bearing formation, the fluid comprising an aqueous phase and a hydrocarbon phase; and, simultaneously with the fluid production, injecting a sand control agent into the well adjacent the production zone at a rate to obtain a wellhead concentration of the sand control agent in the aqueous phase of the fluid of from about 10 to about 1000 ppm active. The sand control agent is a quaternized acylated condensed alkanolamine.

Chakrabarty, T.; Thomas, R.

1986-11-18

250

Fluidized bed combustion  

SciTech Connect

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

Hodgkin, A.F.

1980-12-16

251

Bed load transport by bed form migration  

NASA Astrophysics Data System (ADS)

A theoretically-based methodology is presented for the determination of bed load transport from high-resolution measurements of bed surface elevations for steady-state or developing dunes. The methodology is based on the general form of the Exner equation for sediment continuity and requires information on the distribution of sediment volume concentration as well as the migration velocity of bed layers. In order to determine layer speeds, a new method based on cross-correlation analysis of elevation slices is proposed. The methodology is tested using artificially-created data as well as data from a physical model and from a flume study of developing bed forms. The analyses show the applicability of the method to determine bed load transport without the need to introduce assumptions about the form of the migrating surface. It is shown that predicted transport rates match measured or theoretical transport rates for steadily moving bed forms of an arbitrary shape. The method can also be used to predict transport rates over deforming bed forms, with the reasons for potential deviations between predicted and measured or theoretical transport rates for deforming bed forms identified and discussed. It is further shown that a simplified bulk-surface approach, that is relatively straightforward to apply and in which it is assumed that bed-layer velocity is constant with depth, gives results that are comparable to analyses based on determined bed-layer velocity variation with depth.

Aberle, Jochen; Coleman, Stephen E.; Nikora, Vladimir I.

2012-12-01

252

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

253

Apparatus for processing bituminous sands  

Microsoft Academic Search

An apparatus for processing bituminous sands to recover petroleum is provided. The apparatus is preferably a multicell structure, principal cells of which include bottom stirrer zones and upper quiet zones separated from the stirrer zones by baffles. Continuous through-plant feed is provided for the plant structure by partially processed sands being urged into subsequent cells for continued processing. An oil

Brimhall

1971-01-01

254

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

Microsoft Academic Search

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

Paul J. Hearty; Michael J. O’Leary

2008-01-01

255

Atlas of Dutch drift sands  

NASA Astrophysics Data System (ADS)

The Netherlands is well known for its aeolian landscapes. Frequent storms during the High Middle Ages (1000-1300 AD) reactivated Pleistocene coversands and river dunes and are responsible for the formation of the Holocene drift sands at a scale which is unique for Europe. A hypothesized relationship with farmer practices for making plaggensoils has recently been refuted, because drift sand formation began centuries earlier. The coastal dune belt with their parabolic dunes dates from the same period as the drift sand. An estimate of the extent of drift sands can be made from soil maps: drift sands are too young to show much profile development (Regosols). With this method Koster estimated the maximum extent of Holocene drift sands in the Netherlands to be about 800 km2 (Koster 2005). Laser altimetry allows a more precise estimate of the total surface affected by wind from the characteristic relief patterns produced by the Holocene wind, which is different from the smooth surface of cover sand deposits. Laser altimetry has been used before to investigate the mechanism of drift sand formation (Jungerius & Riksen 2010). Most of the surface affected by wind is not active anymore, but the tell-tale rough surface survived ages of different landuse. The total affected surface amounts to 825 km2. It is noteworthy that both methods give comparable results. We recorded a total number of 367 of affected areas of varying shapes, ranging in size from 1.6 ha to a large complex of drif sands of 7,119.5 ha. As is to be expected from their mode of origin, most occurrences are associated with cover sands, and with river dunes along the river Meuse and smaller rivers in other parts of the country. Particularly the final phases of cover sand and river dunes that show more relief as parabolic dunes were affected. There are also small aeolian deposits at the lee side blown from fallow agricultural fields but they are (sub)recent. Most of the relief is irregular, but the larger occurrences associated with push moraines show that drift sand occurs in elongated cells that are parallel to the prevailing SW wind. Their internal structure reflects the characteristic sequence of geomorphological processes: deflation dominant in the south-west, transport and accumulation towards the north east. Literature • Jungerius, P.D., Riksen, M.J.P.M., 2010. Contribution of laser altimetry images to the geomorphology of the Late Holocene inland drift sands of the European Sand Belt. Baltica 23, 1: 59-70. • Koster EA. 2005. Aeolian environments. In The physical Geography of Western Europe, Koster EA (ed). Oxford Regional Environments, Oxford University Press;139-160.

Riksen, Michel; Jungerius, Pieter

2013-04-01

256

Aging of Athabasca oil sand  

SciTech Connect

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

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

1988-06-01

257

Red clover  

MedlinePLUS

... There isn’t enough information to rate the safety of red clover when applied to the skin. Special precautions & warnings: Pregnancy and breast-feeding: Red clover is LIKELY SAFE when taken by mouth in amounts commonly found in food. But it is ...

258

Red Water  

Microsoft Academic Search

IN connection with the letters on ``red water'' in NATURE of April 4 and 11, it may be of interest to state that a rusty-red coloration of brine and salt in evaporating pools of sea water is common on this coast.

Cyril Crossland

1912-01-01

259

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

260

Energy-efficient method for thermal processing of Utah tar sands  

Microsoft Academic Search

A modification of the existing University of Utah process for thermal recovery of oil from tar sands is described and tested. Main modifications of the existing thermal process include fluid dynamic decoupling of the fluidized bed reactors by using an appropriate oxygen-free gas to fluidize the pyrolysis reactor, and rerouting of the different streams in a pattern that maximizes the

Bezama

1983-01-01

261

On the Behaviour of Hydrodynamic Processes due to the Presence of Submarine Sand Waves  

Microsoft Academic Search

Radar signatures of the sea bed in coastal waters show that submarine sand waves superimposed on sandbanks or tidal current ridges change their orientation and character abruptly at the crest of the ridge. These observations were made when studying air- and spaceborne radar images of the southern North Sea (McLeish et al., 1981). Similar phenomena were already reported by analysing

Ingo HENNINGS; Blandine LURIN; C. VERNEMMEN

262

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

263

Movement of tagged dredged sand at thalweg disposal sites in the upper Mississippi River  

SciTech Connect

Thalweg disposal experiments have been conducted at three sites on the upper Mississippi River. During normal channel maintenance, hydraulically dredged sand was tagged with sand coated with fluorescent dye prior to disposal as a pile in the thalweg. In postdisposal surveys surficial bottom sediment samples were collected in the disposal area and in the thalweg and border areas downstream to determine the movement of the dredged sand relative to environmentally sensitive river habitats. The experiments were initiated in successive years, and the tagged sand has been tracked for 1 to 3 years, depending on the site. Although the downstream movement of the dredged sand was not the same at each site, the general pattern of behavior was similar. Downstream movement was confined primarily to the main channel and occurred in response to periods of high river discharge. There was no statistically significant evidence of dredged sand dispersing out of the main channel into nearby border areas or sloughs. The distributions of dyed sand in cores from one site suggest that the dredged sand has been incorporated into natural bed forms. 7 refs., 5 figs.

Ditmars, J.D.; McCown, D.L.; Paddock, R.A.

1986-01-01

264

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

265

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

PubMed

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

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

2007-12-01

266

Sculpting sandcastles grain by grain: self-assembled sand towers.  

PubMed

We study the spontaneous formation of granular towers produced when dry sand is poured on a wet sand bed. When the liquid content of the bed exceeds a threshold value W*, the impacting grains have a nonzero probability to stick on the wet grains due to instantaneous liquid bridges created during the impact. The trapped grains become wet by the capillary ascension of water and the process continues, giving rise to stable narrow towers. The growth velocity is determined by the surface liquid content which decreases exponentially as the tower height augments. This self-assembly mechanism (only observed in the funicular and capillary regimes) could theoretically last while the capillary rise of water is possible; however, the structure collapses before reaching this limit. The collapse occurs when the weight of the tower surpasses the cohesive stress at its base. The cohesive stress increases as the liquid content of the bed is reduced. Consequently, the highest towers are found just above W*. PMID:23214775

Pacheco-Vázquez, F; Moreau, F; Vandewalle, N; Dorbolo, S

2012-11-09

267

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

268

Red Sky with Red Mesa  

ScienceCinema

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

269

Red Capes, Red Herrings, and Red Flags.  

ERIC Educational Resources Information Center

The argument that the personality structures obtained from retrospective ratings reflect semantic similarity structures has been as provocative as a red cape in the bull ring. High congruence between those two kinds of structures seems well established. What is less clear is how and why those structures differ from that for immediate judgments of…

Fiske, Donald W.

270

IOCC monograph series: tar sands  

SciTech Connect

This is a collection of important papers published on tar sand resources and technologies. It includes nineteen previously published significant technical reports which describe tar sand resources and related technologies. The reports are primarily descriptions of the United States resource and efforts to develop that resource; however, several reports describing Canadian tar sand activities are included because they are the only available publications dealing with the respective technology areas. The republished reports represent the following categories: World Resource Overview; US Resource Overview (Utah, California, Kentucky, Kansas, Missouri, Oklahoma); Extraction Technologies (including in-situ and mining-and-plant-extraction); Field Trials and Commercialization; and Environmental Assessment. (DP)

Ball, D.; Marchant, L.C.; Goldburg, A. (eds.)

1982-01-01

271

Nail Bed Injuries  

MedlinePLUS

... grafted from the same finger or from other digits. Tendon injury may require splinting or pinning. Local ... bed can be reconstructed with grafts from other digits. Grafts may be taken from the nail bed ...

272

Stratigraphic signature of meso- and macrotidal coastal sand body sequences  

SciTech Connect

Numerous cores up to 4.6 m in length from the Wadden Sea of Germany and Louisa Creek, Queensland coast, Australia show a marked absence of tidal structures although spring tides of these two environments are > 3 m and > 6 m respectively. Both areas accumulate well-sorted sand with small amounts of shell and mud drapes or flasers. In the Wadden Sea tidal bedding is present locally and tidal bundles are present in cores from channel margins where megaripples are prominent. Cores from the tidal flats show ripple cross-strata formed by waves. Cores from Louisa Creek show no tidal bundling and little bidirectional cross-strata although the surface of the sand bodies is dominated by megaripples that reverse direction with the tidal cycles. These data suggest that much of the tidally influenced sedimentation that is preserved in the stratigraphic record will probably not be interpreted as such.

Davis, R.A. Jr. (Univ. of South Florida, Tampa, FL (United States). Dept. of Geology)

1993-03-01

273

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

SciTech Connect

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

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

1993-11-01

274

Process to separate bituminous material from sand (tar sands)  

SciTech Connect

Bituminous sand such as oil sand or tar sand is mixed with a halogenated organic solvent which has a density greater than that of water at the same temperature. The slurry is continuously transferred to a conveyor system which is at least partially submerged in water, with the slurry being fed onto the portion of the conveyor which is submerged. As the sands move through the water on the conveyor, the organic solvent containing the bituminous material separates from the sand and forms a separate phase beneath the water. The sands ultimately move upwardly on the conveyor through the surface of the water. The organic phase is removed from beneath the water surface and the halogenated solvent is flashed therefrom in a flash evaporator chamber. Solvent vapors are withdrawn from the evaporator chamber by a compressor, and the compressed vapors are introduced into a condenser chamber. A heat exchange medium is continuously circulated between the condenser and evaporator chambers, with heat being transferred from the heat exchange medium in the evaporator and back to the heat exchange medium in the condenser. Bituminous organic material is withdrawn from the evaporator chamber and condensed solvent is recovered from the condenser. Preferably, the heat exchange means comprises a plurality of heat pipes, with mutually respective end portions of the heat pipes extending into the condenser chamber and the other end portions extending into the evaporator chamber.

Gagon, H.W.

1982-08-03

275

Destruction of N2O over Different Bed Materials  

NASA Astrophysics Data System (ADS)

Since under fluidized bed conditions N2O is produced as a by product of the De-NOx process, the thermal decomposition of N2O was investigated under conditions relevant to those in FBC installations. Laboratory experiments were made in a current of nitrogen using a fixed bed of pure quartz sand or sand with 10% (wt.) of the solids tested, CaO and Fe2O3. With a sand bed the decomposition was slightly faster than in the empty reactor and the reaction was first order with respect to [N2O]. Both fresh CaO and Fe2O3 strongly catalysed N2O decomposition. Their effectiveness diminished after they were heated to temperatures typical for FBC, but they still retained appreciable activity. This activity went down with increasing particle size. The flue gas components investigated were O2, water vapour and CO2. Their presence appeared to interfere with N2O decomposition and increased with the concentration of the additive. The observations indicated that this could only be due to heterogeneous effects. Thus the effects of the bed solids and of the gas phase components are opposed. The effects associated with N2O decomposition have proved to be surprisingly complex and instead of supplying simple answers, this work uncovered more problems.

Pilawska, M.; Zhang, H.; Hout, X. S.; Liu, Q.; Lu, J. F.; Yue, G. X.

276

Modelling and experimental validation of a fluidized-bed reactor freeboard region: Application to natural gas combustion  

Microsoft Academic Search

A theoretical and experimental study of natural gas–air mixture combustion in a fluidized bed of sand particles is presented. The operating temperatures are lower than a critical temperature of 800°C above which the combustion occurs in the vicinity of the fluidized bed. Our study focusses on the freeboard zone where most of the methane combustion takes place at such temperatures.

S. Dounit; M. Hemati; R. Andreux

2008-01-01

277

Fluidized bed combustion  

Microsoft Academic Search

This patent describes a vessel. It comprises a fluid bed for continuously incinerating fuel comprising tire segments and the like which comprise metallic wire tramp and for concurrently removing tramp and bed materials at a bottom effluent exit means of the vessel, the vessel further comprising static air distributor means at the periphery of the bed comprising a substantially centrally

N. K. Sowards; M. L. Murphy

1991-01-01

278

Response of bed surface patchiness to reductions in sediment supply  

NASA Astrophysics Data System (ADS)

River beds are often arranged into patches of similar grain size and sorting. Patches can be distinguished into "free patches," which are zones of sorted material that move freely, such as bed load sheets; "forced patches," which are areas of sorting forced by topographic controls; and "fixed patches" of bed material rendered immobile through localized coarsening that remain fairly persistent through time. Two sets of flume experiments (one using bimodal, sand-rich sediment and the other using unimodal, sand-free sediment) are used to explore how fixed and free patches respond to stepwise reductions in sediment supply. At high sediment supply, migrating bed load sheets formed even in unimodal, sand-free sediment, yet grain interactions visibly played a central role in their formation. In both sets of experiments, reductions in supply led to the development of fixed coarse patches, which expanded at the expense of finer, more mobile patches, narrowing the zone of active bed load transport and leading to the eventual disappearance of migrating bed load sheets. Reductions in sediment supply decreased the migration rate of bed load sheets and increased the spacing between successive sheets. One-dimensional morphodynamic models of river channel beds generally are not designed to capture the observed variability, but should be capable of capturing the time-averaged character of the channel. When applied to our experiments, a 1-D morphodynamic model (RTe-bookAgDegNormGravMixPW.xls) predicted the bed load flux well, but overpredicted slope changes and was unable to predict the substantial variability in bed load flux (and load grain size) because of the migration of mobile patches. Our results suggest that (1) the distribution of free and fixed patches is primarily a function of sediment supply, (2) the dynamics of bed load sheets are primarily scaled by sediment supply, (3) channels with reduced sediment supply may inherently be unable to transport sediment uniformly across their width, and (4) cross-stream variability in shear stress and grain size can produce potentially large errors in width-averaged sediment flux calculations.

Nelson, Peter A.; Venditti, Jeremy G.; Dietrich, William E.; Kirchner, James W.; Ikeda, Hiroshi; Iseya, Fujiko; Sklar, Leonard S.

2009-06-01

279

Combustion of hydrogen in a bubbling fluidized bed  

SciTech Connect

The combustion of hydrogen in a hot, bubbling bed of quartz sand fluidized by air has been studied for the first time, by injecting hydrogen just above the distributor, via six horizontal fine tubes of Cr/Ni. Overall the fluidizing gas was oxygen-rich, with the composition varying from nearly stoichiometric to very lean mixtures. With the bed initially fluidized at room temperature, combustion (after ignition by a pilot flame) occurs in a premixed flame sitting on top of the bed. When the sand warms up, combustion becomes explosive in bubbles leaving the bed, exactly as with a hydrocarbon as fuel. However, in contrast to hydrocarbons, it is clear that when the bed reaches 500-600 C, heat is produced both above the top of the bed (because of H{sub 2} bypassing the bed) and very low down in the bed. In fact, with hydrogen as fuel, the location of where bubbles ignite descends abruptly to low in the sand; furthermore, the descent occurs at {proportional_to}500 C, which is {proportional_to}100 K below the ignition temperature predicted by well-established kinetic models. However, the kinetic models do reproduce the observations, if it is assumed that the Cr/Ni hypodermic tubes, through which the fuel was injected, exert a catalytic effect, producing free H atoms, which then give rise to HO{sub 2} radicals. In this situation, kinetic modeling indicates that bubbles ignite when they become sufficiently large and few enough to have a lifetime (i.e. the interval between their collisions) longer than the ignition delay for the temperature of the sand. The amounts of NO found in the off-gases were at a maximum (24 ppm), when the bed was at {proportional_to}500 C for {lambda}=[O{sub 2}]/[O{sub 2}]{sub stoich}=1.05. The variations of [NO] with [air]/[H{sub 2}] and also temperature indicate that NO is produced, at least partly, via the intermediate N{sub 2}H. In addition, the air-afterglow emission of green light (from NO+O{yields}NO{sub 2}+h{nu}) was observed in the freeboard, indicating the presence there of both NO and free atoms of oxygen for 1.05<{lambda}<1.1. (author)

Baron, J.; Bulewicz, E.M.; Zukowski, W. [Faculty of Chemical Engineering and Technology, Cracow University of Technology, ul. Warszawska 24, 31 - 155 Krakow (Poland); Kandefer, S.; Pilawska, M. [Faculty of Environmental Engineering, Cracow University of Technology, ul. Warszawska 24, 31 - 155 Krakow (Poland); Hayhurst, A.N. [Department of Chemical Engineering, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom)

2009-05-15

280

A model for the simulation of coupled flow-bed form evolution in turbulent flows  

NASA Astrophysics Data System (ADS)

We develop a three-dimensional numerical model to simulate bed form dynamics in a turbulent boundary layer. In the numerical model, hydrodynamics is solved in a moving generalized boundary-fitted curvilinear coordinate system, such that the domain boundary exactly follows complex time-dependent bed form geometry. The resolved turbulent features are computed via large-eddy simulation, while the subgrid scale turbulent motions are modeled with a dynamic mixed model. A second-order accurate arbitrary Lagrangian-Eulerian method is used to guarantee conservation of sediment mass, while the grid moves arbitrarily due to the motion of the bed. Transport of suspended load is modeled using the Eulerian approach with a pickup function as the bottom boundary condition for sediment entrainment at the bed. Transport of bed load and suspended load are combined in a mass balance equation for the bed, which evolves due to the spatiotemporally varying bed stress induced by the turbulent flow field above the bed and gravity (gravity-induced avalanche flow). Motion of the bed in turn affects the flow field in a coupled hydrodynamic moving bed simulation, in which bed features evolve due to resolved details of the turbulent flow. We compare different bed elevation models and demonstrate the capability of the present model through simulation of sand ripple formation and evolution induced by turbulence in an oscillatory flow. A resolution study demonstrates the need for fine grid resolution to resolve a bulk of the near-wall turbulence, which is essential for bed form initiation.

Chou, Yi-Ju; Fringer, Oliver B.

2010-10-01

281

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

SciTech Connect

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

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

1993-09-01

282

Studies of Phlebotomine Sand Flies.  

National Technical Information Service (NTIS)

A preliminary key to the phlebotomine sand flies of Kenya was prepared as an aid to identification. The need for fresh material readily apparent. Further progress was made on illustrating important features of New World species, necessary for inclusion in...

D. G. Young

1980-01-01

283

METHOD OF PROCESSING MONAZITE SAND  

DOEpatents

A method is given for the pretreatment of monazite sand with sodium hydroxide. When momazite sand is reacted with sodium hydroxide, the thorium, uranium, and rare earths are converted to water-insoluble hydrous oxides; but in the case of uranium, the precipitate compound may at least partly consist of a slightly soluble uranate. According to the patent, monazite sand is treated with an excess of aqueous sodium hydroxide solution, and the insoluble compounds of thorium, uranium, and the rare earths are separated from the aqueous solution. This solution is then concentrated causing sodium phosphate to crystallize out. The crystals are removed from the remaining solution, and the solution is recycled for reaction with a mew supply of momazite sand.

Calkins, G.D.

1957-10-29

284

Modern Graywacke-Type Sands.  

PubMed

A preliminary study of more than 100 deep-sea cores from abyssal plains has revealed two examples of recent muddy sands of the graywacke type which, together with the microcrystalline matrix, form a bimodal-size distribution sands have a well-sorted framework of quartz, feldspar, and rock fragments which, together with the microcrystalline matrix, form a bimodal-size distribution that is also typical of ancient graywackes. The matrix is considered to be primary. PMID:17775982

Hollister, C D; Heezen, B C

1964-12-18

285

Aeolian sand transport: a wind tunnel model  

Microsoft Academic Search

Wind sand transport is an important geological process on earth and some other planets. Formulating the wind sand transport model has been of continuing significance. Majority of the existing models relate sand transport rate to the wind shear velocity based on dynamic analysis. However, the wind shear velocity readapted to blown sand is difficult to determine from the measured wind

Zhibao Dong; Xiaoping Liu; Hongtao Wang; Xunming Wang

2003-01-01

286

Alberta's oil sands in-situ pilots  

SciTech Connect

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

Phillips, R.S.

1981-01-01

287

Tensile Strength Characteristics of Unsaturated Sands  

Microsoft Academic Search

Tensile strength characteristics of unsaturated sands are examined through a combined theoretical and experimental study. The characteristics of tensile strength in all three water retention regimes of pendular, funicular, and capillary are examined. A simple direct tensile strength apparatus is employed to determine tensile strength for sands with a broad range of particle sizes from silty sand to fine sand

Ning Lu; Bailin Wu

2007-01-01

288

Physical characteristics of sand injectites  

NASA Astrophysics Data System (ADS)

Almost two hundred years of research is reviewed that focuses on the physical characteristics of sandstone intrusions. It is concerned with mechanisms of sand injection, particularly with fluid-grain transport and sedimentation processes during the remobilization, injection and extrusion of sand. Outcrop and subsurface studies in combination with laboratory experimental data are drawn on to present the state-of-the-art of sand injection. The text covers 1) geometry, internal structure, and microtexture of deformed parent units, injected and extruded sandstones, 2) host-strata and their seal characteristics that contribute to basin-wide overpressure generation, 3) common trigger mechanisms for sand injection such as high magnitude seismicity and the rapid injection of large volumes of fluids, 4) fluid types that drive sand into fractures, 5) hydrofracture mechanisms that induce regional-scale seal failure, 6) liquefaction and fluidization processes that transport sand into fractures, 7) sedimentation processes in fractures, 8) the flow regime of fluidized sand during injection, 9) post-sand-injection fluid flow and diagenesis, 10) porosity and permeability characteristics of injected sandstones and 11) post-sand-injection fluid-flow over geological timescales. Processes of sand remobilization, injection, and extrusion are complex and depend on many interrelated factors including: fluid(s) properties (e.g. pressure, volume, composition), parent unit and host-strata characteristics (e.g. depositional architecture, grain size and distribution, clay-size fraction, thickness, permeability) and burial depth at the time of injection. Many studies report erosional contacts between host strata and injected sands and these record high-velocity, erosive flow during injection. The flow regime is poorly constrained and similar features are interpreted as records of laminar and turbulent flow, or both, during injection. Internal structures are common in sandstone intrusions and can be accounted for by a variety of processes. The interpretational limits largely result from a lack of laboratory experiments that focus on developing analogues for sand injection. The relationship between grain fabric developed during injection and its control on permeability in sandstone intrusions is poorly understood and failure to advance this field of research will hinder the quantitative characterization of sandstone intrusions as fluid-flow conduits during basin evolution. We conclude that future research should focus on: 1) quantification of sediment transport modes under different flow conditions in different fracture dimensions with laboratory data relevant to sand injection; 2) estimation of the effect of injection on the bulk permeability of otherwise low-permeability seals (host strata) so that their effect on fluid flow can be assessed at all scales; and 3) incorporation of sand injection into quantitative basin models. Although an enormous amount of data have arisen from existing studies there remains a need to advance many fields of research related to sand injection so that the significance of these important structures can be fully appreciated in the geological record.

Hurst, Andrew; Scott, Anthony; Vigorito, Mario

2011-06-01

289

A modified probability distribution of ejection state of sand grains in equilibrium aeolian sand transport  

Microsoft Academic Search

Equilibrium sand transport is simulated by stochastic Lagrange particle tracking method combined with probability distribution of initial ejection state of sand grains. Comparing the simulated vertical profile of horizontal sand mass flux and the experimental profiles, a modified exponential distribution is suggested to describe ejection speed and angle of sand grains in equilibrium sand transport. This modified exponential distribution is

Mao Xing; Liejin Guo

2004-01-01

290

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

291

Dynamics of sand and mud mixtures: A multiprocess-based modelling strategy  

NASA Astrophysics Data System (ADS)

Mixed sediments are constituted of cohesive and non-cohesive materials with distinct behaviours that numerical models traditionally manage separately. This paper first introduces a rapid state of the Art in sediment transport modelling in order to point out the specific requirements for process-based models applied to mixed sediments. Based on a preliminary study by Waeles et al. (2007), which showed the validity of the advection approach to compute fine sand transport, a complete modelling strategy is described: it is applied to the suspended transport of sand and mud mixtures, and accounts for consolidation of mixed sediments. Special care is paid to the realistic representation of the structure and density of sand and mud mixtures, and to the segregation in consolidating sediment layers. The model state variables are the different classes of particles, generally classified according to their size, and grouped into categories that are either transported as bedload or in suspension. The bed is described as thin layers characterised by a distribution of these classes. The erosion law for fine sands and for sand and mud mixtures is a function of the excess shear stress calibrated against measurements in a small flume. The transition between cohesive and non-cohesive behaviours is parameterised through a critical mud fraction that depends on the sand grain size: the coarser the sand, the higher the mud content before the sediment becomes cohesive. The consolidation module is based on Gibson equation formulated for each class, and modified to account for segregation. Constitutive relationships are calibrated by means of laboratory settling tests. In the deposition module, new deposits may be managed in different ways (creation of a new layer or integration into the existing surficial layer) depending on the mud fraction and its relative concentration. When deposited material is mixed with the surficial sediment, pores between coarser particles are first filled up with finer particles before increasing the layer thickness. The new modelling frame has first been used to simulate laboratory settling tests with mixed sediments. When the initial mixture density is low, sand particles can settle through the mud and form a dense sandy layer on the bottom. In a second application, the model is used to describe sorting processes when tidal currents re-suspend a sand and mud mixture. A sand layer is then likely to form within the sediment, while the surficial layers are muddier. A dynamic bed armouring process is shown: although sand is easily resuspended, eroded grains in the sand layer settle rapidly, reducing the erosion of underlying sediment. Resulting suspended sediment concentration is strongly reduced, as well as sediment fluxes. The application demonstrates the model ability to simulate layering processes and time-variations of sediment erodibility.

Le Hir, Pierre; Cayocca, Florence; Waeles, Benoît

292

Architectural elements and depositional model of Bahamian-type ooid marine sand belts postulated from surface features  

SciTech Connect

Modern marine ooids are currently forming along the platform margins of Great Bahama and Little Bahama Bank as strike-oriented marine sand belts. Other workers showed that these types of sand bodies consist of flood ramps and shields, and cross-cutting channels that terminate in spillover lobes. Sediment transport is generally perpendicular to the sand belt's axis. Although ooid sands are transported locally by daily tidal currents and waves, wholesale movement of an entire sand body probably only occurs during hurricanes. A completely preserved Bahamian-type marine sand belt should consist of an elongate (parallel with paleostrike), convex-upward body several miles long, and up to about 15-20 ft thick. Isochores should delineate the ramp and shield areas as the thickest zones and the channels as cross-cutting thin zones. Thin channel fills should terminate near leeward margins and pass into thicker zones representing spillover lobes. Large-scale, unidirectional cross-beds should be present in both the basal part of the sand body and in the spillover lobes, and abruptly overlie bioturbated wackestones and/or mudstones of the platform interior. Smaller bidirectional sets should prevail in the upper parts of the sand body. If the sand body prograded during deposition, its seaward margin may contain a gradational coarsening-upward sequence.

Handford, C.R. (ARCO Oil and Gas Co., Plano, TX (USA))

1989-08-01

293

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

NASA Astrophysics Data System (ADS)

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

Wilkins, D. E.; Clement, W.

2007-12-01

294

Micromechanical Modeling for the Deformation of Sand with Non-coaxiality Between Stress and Material Axes  

NASA Astrophysics Data System (ADS)

This research project has taken the micromechanics approach to model the strength and deformation behavior of inherently anisotropic sand subjected to stresses non-coaxial with the material axes. Asymmetric sand grains, such as elongated sand grains, are likely to develop a preferred orientation when deposited during the process of alluvial sedimentation, creating an inherently anisotropic material fabric with horizontally oriented bedding planes. Sand thus exhibits different strength and stress-strain behavior dependent on the direction of loading with respect to the axes of the soil. Accounting for non-coaxiality between the stress and material axes is paramount for the accurate prediction of soil's response to applied loads; however, despite the numerous advancements in constitutive models and numerical methods for geotechnical analysis, the problem of accounting for the effect of non-coaxiality between stress and material axes on soil behavior has not been satisfactorily addressed. Drained hollow cylinder torsional shear (HCTS) compression tests on Toyoura sand were simulated, where the direction of the major principal stresses were applied at various angles to the material axes ranging from 0° to 90° from vertical (i.e., ranging from normal to parallel with the bedding plane). Anisotropic behavior has been attributed to interlocking of the sand particles, where the interlocking is least and sliding occurs most easily on the bedding plane. The degree of interlocking was taken as a material property which varies in three dimensions with respect to the material axes, and has been shown to account for observed anisotropy of material strength. Anisotropy of elastic and plastic strain was accounted for, as was the volumetric strain behavior. The developed micromechanics model has been shown to be capable of predicting anisotropy of strength and stress-strain behavior resulting from non-coaxiality of the stress and material axes.

Bennett, K. C.; Chang, C. S.; Borja, R. I.

2011-12-01

295

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

Microsoft Academic Search

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

Zafar Iqbal; Robert B. Bjorklund

2011-01-01

296

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

USGS Publications Warehouse

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

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

1991-01-01

297

Influence of Salinity on pH and Aluminum Concentration on the Interaction of Acidic Red Soil with Seawater  

Microsoft Academic Search

Contamination of acidic red soil in the coastal areas of Okinawa Islands is a serious environmental problem. This study was conducted to examine the effects of the salinity on pH and aluminum concentration when the acidic red soil interacts with seawater. Acidic red soil from Gushikawa recreation center was fractionated into bulk soil, coarse sand and silt + clay. Different

Mohamed M. Kombo; Said A. Vuai; Maki Ishiki; Akira Tokuyama

2005-01-01

298

The distribution of brick red lutite in the western North Atlantic  

Microsoft Academic Search

One method used to analyze deep water circulation is to track the path of a unique sediment type input from a point source. A well known point source sediment is the late glacial brick red lutite of the western North Atlantic. Eroded from Carboniferous red beds in the Canadian maritime provinces, red detritus was transported out the Cabot Straits and

F. T. Jr. Barranco; W. L. Balsam

1988-01-01

299

Geology on a Sand Budget  

NSDL National Science Digital Library

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

Kane, Jacqueline

2004-09-01

300

Sand fracturing vs frac acidizing  

SciTech Connect

Production histories of two wells were used to compare performances of fracture acidizing and sand fracturing treatments in a study that compared stimulation results of the Ratcliffe Formation in the Williston Basin. The study concluded that with a computer model and production history, fracture geometry may be calculated through curve matching. Use of this method may be helpful in the design of future stimulation jobs. Results of this study indicate greater well production rates and greater cumulative production from sand fracturing than equivalent cost fracture acidizing treatment.

Bailey, D.E.

1984-02-01

301

Dam-break flow on mobile bed in abruptly widening channel: experimental data  

Microsoft Academic Search

This research presents experiments of dam-break flow on mobile bed in an abruptly expanding channel, the wider section being twice as wide as the narrow. The bed material consisted of coarse uniform sand. The flow near the one-sided flume expansion induces a two-dimensional morphological evolution. Important scour at the corner of the abrupt expansion was observed, while sediment deposition occurred

Laurent Goutiere; Sandra Soares-Frazão; Yves Zech

2011-01-01

302

Treatment of chemical-pharmaceutical wastewater in packed bed anaerobic reactors.  

PubMed

Biological degradation in packed bed anaerobic mesophilic reactors with five different support materials was studied for the treatment of chemical-pharmaceutical wastewater with high COD (23-31 g/L), which contains toxic organic compounds. Experimental up-flow bio-filters were operated at different organic loads for a two-year period. Removals of 80-98% were obtained in the reactors with sand, anthracite and black tezontle, but at relatively low organic loads, less than 3.6 kg m(-3)d(-1). The reactor with granular activated carbon (GAC) had a better performance; efficiencies higher than 95% were obtained at loads up to 17 kg m(-3)d(-1) and higher than 80% with loads up to 26 kg m(-3)d(-1). Second in performance was the reactor with red tezontle which allows COD removals higher than 80% with loads up to 6 kg m(-3)d(-1). The use of GAC as support material allows greater biodegradation rates than the rest of the materials and it makes the process more resistant to organic load increases, inhibition effects and toxicity. Methanogenic activity was inhibited at loads higher than 21.9 kg m(-3)d(-1) in the GAC-reactor and at loads higher than 3.6 kg m(-3)d(-1) in the rest of the reactors. At loads lower than the previously mentioned, high methane production yield was obtained, 0.32-0.35 m3CH4/kg CODremoved. PMID:16939097

Nacheva, P M; Peña-Loera, B; Moralez-Guzmán, F

2006-01-01

303

Visualization of fluidized-bed heat exchanger in upward/downward flow condition by neutron radiography  

NASA Astrophysics Data System (ADS)

Heat transfer characteristics of a fluidized-bed heat exchanger are dominated by the characteristics of bed-material movement, especially, in the neighboring region of the heat transfer tube. In the present experiment, a simulated fluidized-bed heat exchanger model was partitioned into two channels to form an upward and downward flow simultaneously in the same fluidized-bed model. Then the total amount of circulating material was kept at the same value even at the different void fractions between two channels. The flow pattern of bed material was visualized by neutron radiography with introducing tracers into the fluidized bed. The simulated fluidized bed consisted of aluminum plates, and the bed materials were sands of 96% SiO2 (mean particle diameter: 0.154 0.321 mm, density: 2550 kg/m3). Bed materials were almost transparent for neutrons. On the contrary, tracer particles of about 1 mm diameter made of B4C with clay were opaque. Thus, the tracer particles were detected clear enough for PTV (Particle Tracking Velocimetry). The fluidized-bed behavior was then discussed in relation to the heat transfer characteristics around the heated tubes submerged in the bed.

Furui, Shuji; Umekawa, Hisashi; Tsuzuki, Masakazu; Okura, Masashi; Ozawa, Mamoru; Takenaka, Nobuyuki

2005-04-01

304

Flow over rough mobile beds: Friction factor and vertical distribution of the longitudinal mean velocity  

NASA Astrophysics Data System (ADS)

The main objective of the present study is to identify the impacts of bed mobility on the vertical profile of the mean longitudinal velocity and on resistance in flows over water-worked beds of poorly sorted mixtures of sand and gravel. Water-worked beds with sediment transport are explicitly distinguished from immobile beds with imposed sediment feed. Flows with different equilibrium sediment transport rates are generated in a laboratory flume. The initial bed mixtures featured combinations of sand and gravel modes. Data collection included instantaneous velocities measured with Laser Doppler Annemometry. Wall similarity, in the sense of Townsend (1976), is assumed. The parameters of the formulae are discussed within three scenarios comprising different definitions ofu* and ks combined with different conceptions of the Von Kármán constant (? flow independent or flow dependent). It is shown that the parameters of the formulae that express the velocity profile vary with the Shields number and with the initial bed composition. The variation is independent of the adopted scenario, except in what concerns the formulation of hydraulic smoothening in the presence of sand sizes, which depends on the definition of ks.

Ferreira, Rui M. L.; Franca, MáRio J.; Leal, JoãO. G. A. B.; Cardoso, António H.

2012-05-01

305

Separating bathymetric data representing multiscale rhythmic bed forms: A geostatistical and spectral method compared  

NASA Astrophysics Data System (ADS)

The superimposition of rhythmic bed forms of different spatial scales is a common and natural phenomenon on sandy seabeds. The dynamics of such seabeds may interfere with different offshore activities and are therefore of interest to both scientists and offshore developers. State-of-the-art echo sounding accuracy allows for the analysis of bed form dynamics on unprecedented spatial and temporal scales. However, the superimposition of bed forms complicates the automated determination of morphodynamic parameters of individual bed form components. In this research we present the extension and comparison of two well-known, automated signal-processing methods for the 1-D and 2-D separation of bathymetric data derived from multibeam echo soundings into different components that each represents a bed form of a particular length scale. One method uses geostatistical filtering, and the other uses a Fourier decomposition of the bathymetric data. The application of both methods in two case studies of the North Sea shows that both methods are successful and that results correspond well. For example, megaripples up to 0.83 m height could be separated from 1.49-2.28 m high sand waves, and regionally averaged lengths and heights of sand waves, as calculated in either method, differ only 0.42-8.2% between methods. The obtained sand wave migration rates differ 7-11% between methods. The resulting morphometric and morphodynamic bed form quantification contributes to studies of empirical behavior and morphodynamic model validation and is valuable in risk assessments of offshore human activities.

van Dijk, ThaiëNne A. G. P.; Lindenbergh, Roderik C.; Egberts, Paul J. P.

2008-12-01

306

Growth of nestling Sand Martins  

Microsoft Academic Search

Nestling Sand Martins are heaviest at 12 days old (on average), but then lose weight. Rapid early growth of the tarsi enables nestlings to move along the burrow towards incoming parents. The nestling period averages 22.3 days, and the young are dependent on their parents for a further 4–5 days after fledging.

A. K. Turner; D. M. Bryant

1979-01-01

307

Sand and Water Table Play  

ERIC Educational Resources Information Center

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

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

2010-01-01

308

Alberta Oil Sands Development Conflict  

Microsoft Academic Search

A systems approach to integrative adaptive management of brownfields on Alberta's oil sands development sites is presented. In particular, the Graph Model for Conflict Resolution (GMCR) is utilized to understand underlying development conflicts among stakeholders, which arise due to competing economic, environmental and societal objectives. The conflict model provides a formalized hypothesis-testing platform for determining responsible policies, which are those

Michele Heng; Keith W. Hipel; Liping Fang

2009-01-01

309

Geology on a Sand Budget  

ERIC Educational Resources Information Center

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

Kane, Jacqueline

2004-01-01

310

Turbulent Bed Cooling Tower.  

National Technical Information Service (NTIS)

The purpose of this work is to determine whether the turbulent bed contactor (TBC), a relatively new and efficient device commonly used for gas scrubbing, can be proven as a competitive cooling system in electric power generation. The turbulent bed employ...

R. G. Barile

1975-01-01

311

Loose sand habitat at the Mojave desert  

NSDL National Science Digital Library

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

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

2007-01-06

312

Behavior of Plastic Sand Confinement Grids.  

National Technical Information Service (NTIS)

The concept of improving the load carrying ability of unbound aggregates, particularly sand, by lateral confinement has been investigated for some time. Extensive full-scale testing of the trafficability of confined beach sand pavement layers has been car...

1986-01-01

313

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

314

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

315

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

316

Adsorption of dyes on Sahara desert sand  

Microsoft Academic Search

Sahara desert sand (SaDeS) was employed as a mineral sorbent for retaining organic dyes from aqueous solutions. Natural sand has demonstrated a strong affinity for organic dyes but significantly lost its adsorption capacity when it was washed with water. Therefore, characterization of both natural and water washed sand was performed by XRD, BET, SEM and FTIR techniques. It was found

Canan Varlikli; Vlasoula Bekiari; Mahmut Kus; Numan Boduroglu; Ilker Oner; Panagiotis Lianos; Gerasimos Lyberatos; Siddik Icli

2009-01-01

317

Erosion of mud\\/sand mixtures  

Microsoft Academic Search

The prediction of sediment erosion is an important issue in coastal engineering projects. There are methods for predicting the erosion of cohesive sediment (mud) and non-cohesive sediment (sand), but there are presently no relationships for mixed sediments. However, natural sediments rarely consist of only mud or sand and the erosional properties of combined mud and sand sediments are required so

Helen Mitchener; Hilde Torfs

1996-01-01

318

Sand reinforced with shredded waste tires  

Microsoft Academic Search

The objective of this study was to investigate the feasibility of using shredded waste tires to reinforce sand. Direct shear tests were conducted on mixtures of dry sand and shredded waste tires. The following factors were studied to evaluate their influence on shear strength: normal stress, sand matrix unit weight, shred content, shred length, and shred orientation. From results of

Gary J. Foose; Craig H. Benson; Peter J. Bosscher

1996-01-01

319

The Valuation of the Alberta Oil Sands  

Microsoft Academic Search

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

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

2008-01-01

320

Sand and Water Table Buying Guide.  

ERIC Educational Resources Information Center

Discusses the importance of sand and water play for young children. Provides a partial list of materials and equipment used to provide sensory experiences at sand and water tables. Offers a buying guide listing manufacturers of sand and water tables, product descriptions, and ordering information. (DR)

Morris, Susan

1990-01-01

321

Seismic polarity reversals in higher impedance gas sands  

SciTech Connect

Most interpreters view processed seismic displays with an understanding of sand/shale reflectivity as provided by available sonic and density logs. Simple synthetic trace seismograms are relatively straightforward for the well-known {open_quotes}bright-spot{close_quotes} world, or zone I condition. For such reflectivity type, impedances ascribed to a single-layer sand model would yield the classic {open_quotes}trough-over-peak{close_quotes} signature on zero-phase wavelet-processed data, with a composite waveform for the {open_quotes}thin bed.{close_quotes} This paper, however, considers anomalous reflections for the higher impedance sands in zone II (case 2) and zone III (case 1), which do not appear as the {open_quotes}dim spots{close_quotes} we might expect if they were gas bearing. Using gas producing field case studies, seismic amplitude/tuning thickness models, subsurface well log information, and auxiliary analyses such as amplitude vs. offset and inversion, this phenomenon is examined for its interpretive significance. Also, by modeling and viewing additional analyses, we demonstrate how such hydrocarbon-associated reflectivity changes occur for certain of the higher impedance members of the Miocene and Pliocene sections in the offshore Gulf of Mexico. Many substantial pay zones found at depth are associated with high-magnitude (bright), trough-over-peak reflections, but derive this exaggerated signature from tuning. Logged impedance values in such sands typically show good contrast on the high side with the shales for the wet condition, and only modest impedance reductions below the shales for the gas pay. As this high-potential province remains yet largely unexploited, owing to poor understanding, improved insights here may result in many new and significant discoveries.

Landwer, W.R.; Neidell, N.S. [Neidell & Associates, Houston, TX (United States)

1994-09-01

322

High-temperature erosion–oxidation of uncoated and FB-CVD aluminized and aluminized–siliconized 9Cr–1Mo steel under fluidized-bed conditions  

Microsoft Academic Search

Fluidized-bed combustion is one of the methods to generate energy in a clean and efficient way from a variety of fuels. However, conditions in fluidized-bed boilers: high temperature, oxidizing atmosphere and impacts by fluidized sand particles, can cause significant degradation of some boiler components, such as heat exchangers, by a combination of oxidation attack and erosion wear. Protective coatings, deposited

E. Huttunen-Saarivirta; S. Kalidakis; F. H. Stott; F. J. Perez; T. Lepistö

2009-01-01

323

Patch behaviour and predictability properties of modelled finite-amplitude sand ridges on the inner shelf  

NASA Astrophysics Data System (ADS)

The long-term evolution of shoreface-connected sand ridges is investigated with a nonlinear spectral model which governs the dynamics of waves, currents, sediment transport and the bed level on the inner shelf. Wave variables are calculated with a shoaling-refraction model instead of using a parameterisation. The spectral model describes the time evolution of amplitudes of known eigenmodes of the linearised system. Bottom pattern formation occurs if the transverse bottom slope of the inner shelf, ?, exceeds a critical value ?c. For fixed model parameters the sensitivity of the properties of modelled sand ridges to changes in the number (N-1) of resolved subharmonics (of the initially fastest growing mode) is investigated. For any N the model shows the growth and subsequent saturation of the height of the sand ridges. The saturation time scale is several thousands of years, which suggests that observed sand ridges have not reached their saturated stage yet. The migration speed of the ridges and the average longshore spacing between successive crests in the saturated state differ from those in the initial state. Analysis of the potential energy balance of the ridges reveals that bed slope-induced sediment transport is crucial for the saturation process. In the transient stage the shoreface-connected ridges occur in patches. The overall characteristics of the bedforms (saturation time, final maximum height, average longshore spacing, migration speed) hardly vary with N. However, individual time series of modal amplitudes and bottom patterns strongly depend on N, thereby implying that the detailed evolution of sand ridges can only be predicted over a limited time interval. Additional experiments show that the critical bed slope ?c increases with larger offshore angles of wave incidence, larger offshore wave heights and longer wave periods, and that the corresponding maximum height of the ridges decreases whilst the saturation time increases.

Vis-Star, N. C.; de Swart, H. E.; Calvete, D.

2008-12-01

324

Heat-transfer studies in circulating fluidized beds  

SciTech Connect

Circulating fluidized bed combustors (CFBC) employing fine limestone offer many potential advantages over the design approach using a shallow bed of coarse limestone, which has dominated efforts to date. Potential advantages include higher combustion efficiencies, reduced limestone needs, simpler fuel and limestone feed system, elimination of unacceptable heat transfer surface erosion, and better turn-down and response rate. These studies investigated the heat transfer in circulating fluidized beds with externally-heated (bed-to-wall) and internally-heated (bed-to-suspended vertical surface) flow. The fluidized particles used were sands (300, 500 {mu}m) and glass beads (600 {mu}m) respectively. The measurement covered a range of superficial gas velocities 4-17 m/sec, suspension densities from 3-140 kg/m{sup 3} and suspension temperature from 40-350 C. The heat transfer coefficients depend strongly on suspension density, but show almost no dependence on gas velocities and bed temperature. A model which predicts the observed relation of heat transfer coefficient to solid thermal properties is based on particle heat absorption. The residence time was assumed to be the same for all particles and calculated to be the time for a particle to fall the length of the jacket. Particles were assumed to move at the terminal velocity along the wall. The results were in good agreement with the prediction of this model.

Sekthira, A.

1988-01-01

325

How many hospital beds?  

PubMed

For many years, average bed occupancy level has been the primary measure that has guided hospital bed capacity decisions at both policy and managerial levels. Even now, the common wisdom that there is an excess of beds nationally has been based on a federal target of 85% occupancy that was developed about 25 years ago. This paper examines data from New York state and uses queueing analysis to estimate bed unavailability in intensive care units (ICUs) and obstetrics units. Using various patient delay standards, units that appear to have insufficient capacity are identified. The results indicate that as many as 40% of all obstetrics units and 90% of ICUs have insufficient capacity to provide an appropriate bed when needed. This contrasts sharply with what would be deduced using standard average occupancy targets. Furthermore, given the model's assumptions, these estimates are likely to be conservative. These findings illustrate that if service quality is deemed important, hospitals need to plan capacity based on standards that reflect the ability to place patients in appropriate beds in a timely fashion rather than on target occupancy levels. Doing so will require the collection and analysis of operational data-such as demands for and use of beds, and patient delays--which generally are not available. PMID:12638714

Green, Linda V

326

Hydrodynamic, sedimentological and morphological processes on Banzu intertidal sand-flat, Tokyo Bay, Japan  

Microsoft Academic Search

Hydrodynamics, sediment suspension and morphological response on Banzu intertidal sand-flat in Tokyo Bay, Japan, were examined through a 6-year survey of bed levels and a short-term field measurement programme performed for 16 days in winter 2000 when fluvial discharge from the adjacent river was negligible. The results of the cross-spectral analysis show that on Banzu Flat semidiurnal or shorter-period components

T. Sun; Y. Uchiyama

2002-01-01

327

Patch behaviour and predictability properties of modelled finite-amplitude sand ridges on the inner shelf  

Microsoft Academic Search

The long-term evolution of shoreface-connected sand ridges is investigated with a nonlinear spectral model which governs the dynamics of waves, currents, sediment transport and the bed level on the inner shelf. Wave variables are calculated with a shoaling-refraction model instead of using a parameterisation. The spectral model describes the time evolution of amplitudes of known eigenmodes of the linearised system.

N. C. Vis-Star; H. E. de Swart; D. Calvete

2008-01-01

328

A generalization of Reiner’s mathematical model for wet sand  

SciTech Connect

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

Mehrdad Massoudi

2011-01-01

329

Design and Shakedown of an Inclined Liquid Fluid-Bed Reactor System.  

National Technical Information Service (NTIS)

This report describes the design and shakedown testing of an inclined liquid fluid-bed reactor system. The system is being developed for processing tar sand with a recycle oil pyrolysis and extraction process to produce a high yield of specialty products....

L. A. Johnson C. Y. Cha

1987-01-01

330

Denitrification in a fluidized bed system using low cost packing material  

Microsoft Academic Search

A fluidized bed reactor was studied for denitrification, using sewage as an electron donor. First, the start?up procedure, volumetric loading rate and organic carbon requirements were analyzed. In a second stage, several packing materials were tested. Selection was based upon availability in developing countries. Tested materials were: sand, coffee grounds (dregs), pumice stone, tezontle stone (volcanic scoria), nut shell and

B. Jimenez; E. Becerril; I. Scola

1990-01-01

331

Studies for Determining Grain Flow in Silt Beds, Using Radioisotope Techniques.  

National Technical Information Service (NTIS)

A process for measuring the flow of solids in silt beds using isotopic techniques was studied. Comparative studies of the initial movement of ground-glass grains and sand grains were made. The method for determining the minimum mass of radioactive grains ...

W. Sanchez

1976-01-01

332

Use of fluidized bed heat exchangers in heat pump systems for improved performance. Technical status report, September 1, 1979-February 29, 1980  

SciTech Connect

Modifications in the system were made to include backup pressure readings and to provide for refrigerant switching to the fluidized bed. Assembly of the finned tubing was completed and the air distributor system for the fluidized bed was designed and constructed. Tests without particles show the system to give uniform air flow over the entire bed surface. 40-60 sand was found to have a predominance of particles at 300 micron diameter which is comparable to GT-2 particles and is to be used as the bed material. Deicing experiments show that for subfreezing conditions fluidized beds will remove ice and also prevent ice formation.

Chen, J.C.; Sarubbi, R.G.

1980-03-25

333

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

334

Measuring and modeling solids movement in a large, cold fluidized bed test facility. Second quarterly report, January 1, 1980March 31, 1980  

Microsoft Academic Search

Movies taken of the sand\\/freon system vs. the cork\\/air system in two bed configurations (rectangular and cylindrical) and tungsten carbide\\/water vs. expanded polystyrene\\/air in a cylindrical bed configuration at U\\/sub mf\\/ and various multiples of U\\/sub mf\\/ showed similarities in bubble growth and solids flow patterns. In addition, in the slugging beds the slugs appear to be nearly equal in

T. J. Fitzgerald; R. V. Mrazek; S. D. Crane

1980-01-01

335

Fluidized bed combustion method  

SciTech Connect

A process is described for fluidized bed combustion of particulate combustible material in a furnace comprising feeding the particulate combustible material to the furnace and imparting a turbulent fluidized bed motion to the particulate combustible material within the furnace through the use of a vibrating screen. The screen is connected to means for vibrating the screen as the principal source of energy for imparting the turbulent fluidizing motion to the combustible material. This feeds combustion air to the fluidized bed of combustible material, discharging products of combustion from the furnace, and causing the fluidized bed to move in substantially horizontal direction so that combustible material is conveyed from the location of feed to the furnace through a combustion stage in the furnace to the location of discharge as combustible products.

Love, R.E.

1986-12-16

336

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

337

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

338

Bed bug deterrence  

PubMed Central

A recent study in BMC Biology has determined that the immature stage of the bed bug (the nymph) signals its reproductive status to adult males using pheromones and thus avoids the trauma associated with copulation in this species. The success of this nymphal strategy of deterrence is instructive. Against the background of increasing problems with bed bugs, this research raises the question whether pheromones might be used to control them. See research article http://www.biomedcentral.com/1741-7007/8/121

2010-01-01

339

Top Ten Bed Bug Tips  

MedlinePLUS

Make sure you really have bed bugs, not fleas or ticks or other insects You can compare your insect to the pictures on our bed bug Web page ... it-yourself freezing as a reliable method for bed bug control. While freezing can kill bed bugs, temperatures ...

340

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.

341

Continuous cleaning of heat exchanger with recirculating fluidized bed  

SciTech Connect

Fluidized bed heat exchangers for liquids have been studied in the United States, the Netherlands, and the Federal Republic of Germany. Between 1965 and 1970, fluidized bed heat exchangers were developed in the United States as brine heaters in seawater desalination. Furthermore, their potential in the utilization of geothermal energy was tested between 1975 and 1980. In the Netherlands, fluidized bed heat exchangers have been developed since 1973 for brine heating and heat recovery in multistage flash evaporators for seawater desalination and, since about 1980, for applications in the process industry. The authors became interested in fluidized bed heat exchangers first in 1978 in connection with wastewater evaporation. The authors emphasize that the results of all these groups were in basic agreement. They can be summarized as follows: 1. The fluidized bed will in many cases maintain totally clean surfaces and neither scaling nor fouling will occur. In cases where even a fluidized bed cannot completely prevent scaling or fouling, the thickness of the layer is controlled. In these cases stable operation maintaining acceptable overall heat transfer coefficients is possible without cleaning. 2. There are always excellent heat transfer coefficients as low superficial velocities of less than ..nu.. < 0.5 m/s. 3. The pressure losses are comparable with those in normal heat exchangers since fluidized bed heat exchangers are mostly operated at low superficial velocities. 4. Feed flow may be varied between 50 and 150% or more of the design feed flow. 5. Erosion is negligible. 6. Fluidized bed particles can be manufactured from all sorts of chemically and mechanically resistant materials, such as sand, glass, ceramics, and metals.

St. Kollbach, J.; Dahm, W.; Rautenbach, R.

1987-01-01

342

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

PubMed

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

Stefanova, R Y

2001-01-01

343

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

NASA Astrophysics Data System (ADS)

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.

van der Wegen, Mick; Dastgheib, Ali; Jaffe, Bruce E.; Roelvink, Dano

2011-03-01

344

Transport of nanoparticles with dispersant through biofilm coated drinking water sand filters.  

PubMed

This article characterizes, experimentally and theoretically, the transport and retention of engineered nanoparticles (NP) through sand filters at drinking water treatment plants (DWTPs) under realistic conditions. The transport of four commonly used NPs (ZnO, CeO2, TiO2, and Ag, with bare surfaces and coating agents) through filter beds filled with sands from either acid washed and calcined, freshly acquired filter media, and used filter media from active filter media, were investigated. The study was conducted using water obtained upstream of the sand filter at DWTP. The results have shown that capping agents have a determinant importance in the colloidal stability and transport of NPs through the different filter media. The presence of the biofilm in used filter media increased adsorption of NPs but its effects in retaining capped NPs was less significant. The data was used to build a mathematical model based on the advection-dispersion equation. The model was used to simulate the performance of a scale-up sand filter and the effects on filtration cycle of traditional sand filtration system used in DWTPs. PMID:24050685

Li, Zhen; Aly Hassan, Ashraf; Sahle-Demessie, Endalkachew; Sorial, George A

2013-09-03

345

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

346

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

347

Wind initiation thresholds of the moistened sands  

NASA Astrophysics Data System (ADS)

The widely accepted Bagnold-type function for calculating threshold wind velocity or shear velocity was developed for dry sands, but surface moisture is an extremely important variable controlling the entrainment process of sands by wind because the tensile force between the water molecules and sand grains produces cohesion. Here we report detailed wind tunnel experimental results on the threshold shear velocity of moistened sand of different sizes. The results show that relative threshold shear velocity, which is the ratio of threshold shear velocity of sand in the moistened state to that in the dry state, is better related to moisture content than threshold shear velocity itself. Function, modified after the Bagnold equation has been developed to estimate the threshold shear velocities of moistened sands. For a given grain size, the threshold shear velocity is proportional to (1 + KM)1/2, where, M is the moisture content, and K is a coefficient depending on grain size.

Dong, Zhibao; Liu, Xiaoping; Wang, Xunming

2002-06-01

348

Sand banks of finite amplitude  

NASA Astrophysics Data System (ADS)

The process which leads to the appearance of sand banks in shallow seas is investigated by studying the growth of small-amplitude perturbations of the sea bottom, forced by oscillatory tidal currents. Since the analysis of field data carried out by Dyer and Huntley (1999) suggests that sand banks are likely to occur where the tidal ellipse is circular or characterized by a low ellipticity, attention is focused on small values of ?, where e is the ratio between minor and major axes of the tidal ellipse. The linear analysis, which considers perturbations of small (strictly infinitesimal) amplitude, shows the existence of a critical value rC of the Keulegan-Carpenter number r of the tide (r = U0*/(h0*?*), U0* and ?* being the amplitude and angular frequency of the velocity oscillations induced by the tide propagation and h0* being the averaged water depth) such that for r smaller than rC the flat bottom configuration is stable, while for r larger than rC the sand banks start to appear. Close to the critical condition, the wavelength of the most unstable mode turns out to be finite. Then a weakly nonlinear analysis is developed which allows the evaluation of the equilibrium amplitude of the bottom forms when the parameter r is close to its critical value. The configuration of the sea bottom, when the bottom forms attain their equilibrium, is characterized by the presence of long ridges, almost parallel to the main axis of the tidal ellipse, with crest-to-crest distances similar to those observed during field surveys. The crests of the bottom forms turn out to be flat, and the extensive shallow waters at the crests are compensated by deep troughs between the ridges.

Tambroni, N.; Blondeaux, P.

2008-10-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

350

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

351

Episodic dynamics of a sand wave field  

Microsoft Academic Search

The morphodynamics of a sand wave field in a flood-dominant channel inside Moriches Inlet was monitored for eight weeks during the summer of 2005. Bathymetric data show sand waves on average are 15 m long and 39 cm high with shallow slip faces. The sand waves remained stationary over the eight-week study. The maximum peak current speeds recorded during this study only

Shelley J. Whitmeyer; Duncan M. FitzGerald

2008-01-01

352

Sand Stabilization with Hydroxy Aluminum Solutions  

Microsoft Academic Search

In many oil-producing reservoirs, sand and other fine-grained rock materials migrate into wells. This influx may decrease oil production by plugging gravel packs, eroding well equipment or completely sanding up wells. A procedure is described for treating such formations with hydroxy-aluminum to stabilize clay minerals and thereby prevent sand and silt production. Hydroxy-aluminum is a relatively inexpensive and commercially available

M. G. Reed; Claude Coppel

1972-01-01

353

The characteristic of streamwise mass flux of windblown sand movement  

NASA Astrophysics Data System (ADS)

Two patterns have been reported in previous literature about the streamwise mass flux of windblown sand movement in steady state; namely, the exponential pattern and the stratification pattern. Although the exponential pattern has been verified by some experimental measurements and numerical simulations, an agreed conclusion is not reached yet. Re-evaluating the previous model, it can be found that the pattern of the PDF (probability density function) distribution of the initial liftoff velocity is the key factor that determines whether the stratification happens or not. If the number of liftoff grains decreases with the increase in liftoff velocity, such as in the case of the exponential distribution, the stratification pattern will not appear. If the number of liftoff grains increases first and decreases later with the increase in liftoff velocity, such as in the case of the log-normal distribution, Gamma distribution and Gaussian distribution, the stratification pattern will come into existence. In addition, the hop height for the initial liftoff velocity, corresponding to the peak value of its PDF distribution, equals the height of the maximum streamwise mass flux. On the basis of some deterministic laws from experimental measurements and numerical simulations of grain/bed impact, a qualitative understanding about the PDF distribution of the liftoff velocity is obtained and the Rayleigh distribution is used for reptating grains. Also included in this paper is a model in which grain/bed impact is discussed and the interaction between the grains and the wind is considered. It is shown that the stratification pattern, composed of a linear increment layer, a saturation layer, and a monotonic decrement layer, indeed exists in the streamwise mass flux of windblown sand movement. Further, as with the average velocity and PDF distribution of the liftoff velocity of the reptating grains, which is determined by the characteristics of grains, the height of the peak value of the streamwise mass flux is also determined by the property of the grains and will be independent of the wind intensity.

Wu, Jian-Jun; Luo, Sheng-Hu; He, Li-Hong

2012-02-01

354

Pyrolysis of Arroyo Grande tar sand and tar sand/oil mixtures.  

National Technical Information Service (NTIS)

Pyrolysis experiments have been performed on Arroyo Grande tar sand and on mixtures of tar sand and SAE 50 oil. Isothermal and nonisothermal tests were performed on a Du Pont model 950 thermogravimetric analyzer (TGA), and larger scale isothermal experime...

T. F. Turner B. E. Thomas L. G. Nickerson

1989-01-01

355

[Model experiments on breathing under sand].  

PubMed

Remarkable autopsy findings in persons who had suffocated as a result of closure of the mouth and nose by sand (without the body being buried) induced us to investigate some aspects of this situation by means of a simple experiment. A barrel (diameter 36.7 cm) with a mouthpiece in the bottom was filled with sand to a depth of 15, 30, 60, or 90 cm. The subject tried to breathe as long as possible through the sand, while the amount of sand inspired was measured. Pressure and volume of the breath, as well as the O2 and CO2 content were also measured. A respiratory volume of up to 31 was possible, even when the depth was 90 cm. After about 1 min in all trials, the subject's shortness of breath forced us to stop the experiment. Measurement of O2 and CO2 concentrations proved that respiratory volume in and out of the sand shifts to atmospheric air without gas exchange, even when the sand depth is 15 cm. Sand aspiration depended on the moisture of the material: when the sand was dry, it was impossible to avoid aspiration. However, even a water content of only 5% prevented aspiration, although the sand seemed to be nearly dry. PMID:3927604

Maxeiner, H; Haenel, F

1985-01-01

356

Minerals yearbook, 1988: Industrial sand and gravel  

SciTech Connect

Production of industrial sand and gravel in 1988 increased to 28.5 million short tons, about a 2% increase over that of 1987, but remained 15% below the record-high production level of 1979. The production increase was due in part to the addition of new operations in California and Tennessee. Imports of industrial sand and gravel decreased about 59% in quantity, but the associated value increased 79%. Exports of industrial sand and gravel increased about 40% in quantity with a slight increase in average value per ton. Domestic apparent consumption of industrial sand and gravel in 1988 was 27.5 million tons.

Bolen, W.P.

1988-01-01

357

Levels of reservoir heterogeneity in a Mississippi River meander belt sand system  

SciTech Connect

Six levels of heterogeneity are present in a Mississippi River meander belt sand system near Dorena, Missouri, and these levels can be applied to reservoir description models. On an oil-field scale, the meander belt (13 million acre-ft of which 9 million acre-ft is sand), with its multiple abandoned channels, is the first level of heterogeneity. Level 2, represented by meander loop sands (1.2 million acre-ft) and single abandoned clay-filled channels, is on a stacked reservoir scale. Individual point bars (70,000 acre-ft) with extensive mud sheets (single reservoir or pool scale) constitute level 3. Lobe sheet units (40 acre-ft) of single well scale contain numerous reactivation surfaces and isolated mud drapes and are the fourth level of heterogeneity. Bedding units (< 10 acre-ft) with impervious bedset boundaries, of flow unit or perforated interval scale, constitute level 5. The sixth level of heterogeneity, individual laminae with variations in textural properties (cubic inches), is associated with interparticle fluid flow. The distribution of permeability barriers and nature of bounding surfaces control vertical and lateral reservoir continuity at the various levels. Poor sorting within and between foreset lamina, as well as infiltrated clay (level 6), are responsible for reducing permeabilities 10-50%. Large planar foresets and trough cross-beds (levels 4 and 5) have permeabilities ranging from 90 to 160 Darcys. Permeabilities measured in clayey sand, silt, and sandy silt beds from the levee, crevasse, and abandoned channel fill range from several millidarcys to 50 darcys, and interbedded clayey silt and clay constituting channel plugs, chute fills, and mud sheets (levels 1, 2, and 3) have essentially no permeability.

Jordan, D.W.; Pryor, W.A.

1989-03-01

358

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

359

Pattern dynamics of sand ripples with a tilted drive.  

NASA Astrophysics Data System (ADS)

When a sand bed is subjected to an oscillatory water flow, vortex ripples perpendicular to the flow are created. The formation of normal ripple patterns is driven by the 'separation zones' created in the troughs between ripples. The wavelength of the ripples is roughly proportional to the amplitude of the fluid motion and is independent of the frequency. Previous experiments performed with sand on a rectangular tray (0.6m x 1m ) oscillated sinusoidally in a closed watertank have shown roughly one-dimentional behaviour: the ripples form as essentially straight lines perpendicular to the water flow. A new circular setup has been built with a turnable tray in order to investigate the pattern dynamics, when a regular ripple pattern is subjected to a flow not perpendicular to the ripples. Preliminary results show the existence of a critical angle of around 30 degrees, above which the ripples do not merely turn back to perpendicular, but recombine partially with neighbour ripples, thus temporarily creating two-dimentional zig-zag patterns.

Bundgaard, F.; Ellegaard, C.; Scheibye, K.; Bohr, T.

2002-11-01

360

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.

361

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

362

Bed bug deterrence.  

PubMed

A recent study in BMC Biology has determined that the immature stage of the bed bug (the nymph) signals its reproductive status to adult males using pheromones and thus avoids the trauma associated with copulation in this species. The success of this nymphal strategy of deterrence is instructive. Against the background of increasing problems with bed bugs, this research raises the question whether pheromones might be used to control them. See research article http://www.biomedcentral.com/1741-7007/8/121. PMID:20828375

Haynes, Kenneth F; Goodman, Mark H; Potter, Michael F

2010-09-09

363

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

364

Fecal indicators in sand, sand contact, and risk of enteric illness among beach-goers  

EPA Science Inventory

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 2 recreational marine beaches were asked on the day of their visit about sand contact. Ten to 12 days...

365

[Spatial distribution patterns of dry sand layer on windward slope of dunes in Horqin Sand Land].  

PubMed

An observation was conducted on the thickness of dry sand layer on the windward slope of mobile and fixed dunes in west Horqin Sand Land, with the spatial distribution of the dry sand layer analyzed. Most of the dry sand layer had a thickness of 5-15 cm, and 92.0% and 98.6% of the mobile and fixed dunes had the dry sand layer with this thickness, respectively. Sand-fixing plants affected the thickness and the spatial distribution of the dry sand layer. There was an obvious spatial difference in the thickness of the dry sand layer on mobile dunes, being much thicker in the upper west areas while much thinner in the lower east areas. The thickness of the dry sand layer varied from 0 to 40 cm, with an average of 9.58 +/- 3.95 cm, and the CV was 41%. The variogram of the spatial distribution of dry sand layer on mobile dunes was expressed as spherical model, with a moderate spatial correlation. In contrast, the thickness of dry sand layer on fixed dunes showed obvious homogeneity, and had less spatial difference. The thickness of the dry sand layer ranged from 0 to 20 cm, with an average of 10.91 +/- 1.70 cm, and the CV was only 16%. PMID:22803448

Zong, Qin; Lamusa, A; Luo, Yong-Ming; Niu, Cun-Yang; Chen, Xue-Feng; Wang, Hai-Yang

2012-04-01

366

Improvement on the evaluation of thinly bedded reservoirs using borehole images in horizontal wells  

SciTech Connect

Conventional downhole resistivity log taken in a vertical well penetrating a thinly bedded formation is adversely affected by the limited vertical resolution of this tool. This type of log allows the identification of thick beds, but fails the detection of thin beds. The vertical formation, an isotropy that affects the resistivity curves in a vertical well, is increased in a horizontal well by the extra dimension that is measured by the tools during the navigation through a layer. In horizontal wells the problem of detecting thin beds of low true resistivity and low bed contrast is magnified by the shoulder bed effect in two dimensions (horizontal and vertical). Additionally, the often-stated concept that the invasion process is shallow just after drilling was proved to be wrong in this reservoir. A proposed methodology is presented for enhancing the petrophysical evaluation. Conventional petrophysical analysis was compared with borehole images and the 3D geological model to understand the heterogeneities. The cuttings from the horizontal well were described in detail and correlated with both the petrophysical evaluation and the borehole images. An additional sedimentary perspective was gained from the horizontal images, thereby increasing the understanding of the depositional model and providing a new dimension to sand body architecture. This information was used to update the 3D geological model used in the simulation study. Borehole images provide a significant definition of the low resistivities of thin sands and proved to be a method to enhance the results of the petrophysical evaluation of this type of reservoir.

Coll, C.; Gamero, H.; Lozada, T.; Chacartegui, F.; Suarez, O. [Maraven, S.A., Caracas (Venezuela)

1996-08-01

367

Comparisons of housing, bedding, and cooling options for dairy calves.  

PubMed

Housing, bedding, and summer cooling were management options evaluated. Holstein calves (42±2 kg of body weight) initially 2 to 5 d of age were managed in southwest Ohio in poly hutches or wire mesh pens in a curtain-sided nursery with no supplemental heat. Calves were fed milk replacer (27% crude protein, 17% fat fed at 0.657 kg of dry matter per calf daily), starter (20% crude protein dry matter, textured, fed free-choice), and water (free-choice). Measurements were for 56 d. In trial 1, 28 calves per treatment were bedded with straw and housed in either hutches or nursery pens. This trial was conducted from September to March; the average temperature was 8°C and ranged from -17 to 31°C. In trial 2a, 16 calves per treatment were managed in nursery pens bedded with straw, in nursery pens bedded with sand, or in hutches bedded with sand. This trial was conducted from May to September; the average temperature was 21°C and ranged from 7 to 33°C. In trial 2b, 26 calves per treatment were housed in nursery pens and bedded with straw. This trial was conducted from May to September; the average temperature was 22°C and ranged from 8 to 34°C. One treatment was cooled with fans between 0800 and 1700 h and the other was not. Data were analyzed as repeated measures in a completely randomized block design by trial, with calf as the experimental unit. In trial 3, air in the nursery and calf hutches used above was sampled 35 d apart for calves aged 5 and 40 d. Air in individual hutches on 2 commercial farms was sampled for 5- and 40-d-old calves for 2 hutch types. Air in the multi-calf hutches was sampled for calves of 75 and 110 d of age. Bacterial concentrations of air samples were analyzed (log10) as odds ratios by Proc Logistic in SAS software (SAS Institute Inc., Cary, NC); differences were declared at P<0.05. In trial 1, weight gain of calves in nursery pens was 6% greater and feed efficiency was 4% greater than that of calves in hutches. In trial 2a, weight gain and starter intake of calves in the nursery with straw bedding were greater and scouring was less than that in calves bedded with sand in the nursery or hutches. The relative humidity was greater in the hutches than in the nursery pens. In trial 2b, weight gain, feed efficiency, and hip width change were greater and breaths per minute were less for calves cooled with fans compared with calves that were not cooled. In trial 3, airborne bacteria concentrations were greater in the hutches than in the nursery pens. Straw bedding (vs. sand), nursery pens (vs. hutches), and summer daytime cooling with fans improved calf weight gain. PMID:21427006

Hill, T M; Bateman, H G; Aldrich, J M; Schlotterbeck, R L

2011-04-01

368

Solute dilution under imbibition and drainage conditions in a heterogeneous structure: Modeling of a sand tank experiment  

NASA Astrophysics Data System (ADS)

This study aims at modeling the transport of a conservative tracer in two dimensions, as experimentally observed in a strongly heterogeneous medium under conditions of variable water saturation during drainage and imbibition. Solute transport experiments were conducted in a sand tank containing an artificial packing of three quartz sands of different particle sizes. The packing was characterized by the presence of numerous homogeneous layers (0.5 × 5 × 5 cm) inclined at 45° and randomly distributed in a tank. Six different stationary flow conditions were sequentially established during imbibition and drainage. When a stationary flow regime was reached, several solute pulses were applied at different positions at the upper surface of the sand structure. The transport regime was studied by monitoring the tracer plumes injected as point-like pulses at the surface, as they travelled through the sand bedding. A textural map was generated from a digital image of the sand bedding. The Richards equation was solved with the experimental boundary conditions assuming homogeneity of the individual sand layers. The hydraulic properties of the three quartz sands were deduced from multistep-outflow column experiments [Ursino N, Gimmi T. Combined effect of heterogeneity, anisotropy and saturation on steady state flow and transport: structure recognition and numerical simulation. Water Resour Res 2004;40. doi:10.1029/2003WR002180]. The convection-dispersion equation was solved on the resulting flow fields for solute pulses of given solute mass applied onto the top boundary at the same positions as in the experiment. The simulated and observed solute concentration distributions were then compared. In agreement with the experimental observations, the simulations reproduced the existence of preferential pathways in those stationary flow fields at low saturation degrees. The values of the vertical and horizontal macroscopic dispersivities obtained from the simulations are smaller than experimentally observed, especially at low flow rates. The simulated solute concentration distributions show a realistic degree of solute dilution quantified as reactor ratio.

Rossi, M.; Ippisch, O.; Flühler, H.

2008-09-01

369

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

370

JAMA Patient Page: Bed Bugs  

MedlinePLUS

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

371

Technology test bed review  

Microsoft Academic Search

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

H. V. McConnaughey

1992-01-01

372

Fluidized bed silicon deposition  

Microsoft Academic Search

The growth of silicon on seed particles from the pyrolysis of silane in a fluidized bed reactor (FBR) was studied. The grown particles were shown to be crystalline and to have a structure which has been interpreted to indicate growth by chemical vapor deposition as well as by the collection (scavenging) of silicon clusters on seed particle surfaces. Scanning electron

G. Hsu; A. Morrison; N. Rohatgi; R. Lutwack; T. MacConnell

1984-01-01

373

Technology test bed review  

NASA Astrophysics Data System (ADS)

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

McConnaughey, H. V.

1992-07-01

374

Bed-Wetting  

MedlinePLUS

... bed-wetting seem to be triggered by certain foods, drinks or activities? Is your child dry during the day? Is your child facing ... the body. Acupuncture may be effective for some children. Diet. Some people believe that certain foods affect bladder function and that removing these foods ...

375

MULTISTAGE FLUIDIZED BED REACTOR  

DOEpatents

A multistage fluidized bed reactor is described in which each of a number of stages is arranged with respect to an associated baffle so that a fluidizing gas flows upward and a granular solid downward through the stages and baffles, whereas the granular solid stopsflowing downward when the flow of fluidizing gas is shut off.

Jonke, A.A.; Graae, J.E.A.; Levitz, N.M.

1959-11-01

376

Gasification of oil sand coke: Review  

Microsoft Academic Search

The production of synthetic crude from the tar sands in Western Canada has been steadily increasing. Most of the delayed coke produced by Suncor is combusted on site, whereas all fluid coke produced by Syncrude is stockpiled. The database on the chemical and physical properties of the oil sand coke, including the composition and fusion properties of the mineral matter,

Edward Furimsky

1998-01-01

377

Hydrodynamic analysis of feeding in sand dollars  

Microsoft Academic Search

Subtidal sand dollars, Dendraster excentricus, assume an inclined posture under conditions of moderate water flow (10 cm s-1 to 2 m s-1). In this posture, when the test is in the usual position parallel to the water flow, the test acts as a lifting body. Analysis of the hydrodynamic characteristics of the sand dollar test was accomplished by slender body

Patricia L. O'Neill

1978-01-01

378

Systems for producing bitumen from tar sands  

Microsoft Academic Search

A system for producing bitumen from unconsolidated tar sands in an open well includes a screen positioned in the well large enough to pass a majority of the formation sand and small enough to retain a gravel packing material, a pair of high pressure fluid lateral nozzles fracturably fastened in the bottom of the screen, a wash pipe extending down

Payton

1978-01-01

379

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

380

Explorations with the Sand and Water Table.  

ERIC Educational Resources Information Center

|Presents sand and water activities for young children as examples of sensory explorations, science activities, and comforting play. Includes information on health and safety precautions, adaptations for children with physical disabilities, the use of other materials, and sand and water toys made from one-liter plastic bottles. (KB)|

Texas Child Care, 2001

2001-01-01

381

Syncrude-oil from Alberta's tar sands  

Microsoft Academic Search

Synthetic crude oil can be produced from bitumen contained in oil sands such as those located in Alberta, Canada. The most recent plant to come on stream, that of Syncrude Canada Ltd., mines the oil sand by open pit methods, recovers the bitumen using the hot water flotation process, and produces synthetic crude from bitumen by coking and hydrotreating. The

1980-01-01

382

New production techniques for Alberta oil sands  

Microsoft Academic Search

Low world oil prices represent a serious threat to expanded commercial development of the Canadian oil sands in the near term, as they do to all of the higher cost alternatives to crude oil such as oil shales and coal liquefaction. Nonetheless, research and field testing of new technology for production of oil from oil sands are being pursued by

M. A. CARRIGY

1986-01-01

383

New Production Techniques for Alberta Oil Sands  

Microsoft Academic Search

Low world oil prices represent a serious threat to expanded commercial development of the Canadian oil sands in the near term, as they do to all of the higher cost alternatives to crude oil such as oil shales and coal liquefaction. Nonetheless, research and field testing of new technology for production of oil from oil sands are being pursued by

Maurice A. Carrigy

1986-01-01

384

Adding Value to Alberta's Oil Sands  

Microsoft Academic Search

A rapidly expanding oil sands industry and a dwindling supply of feedstock for Alberta's ethane-based petrochemical industry have stimulated interest in evaluating bitumen for producing a broad slate of refined products, including petrochemicals. Two industry\\/government studies evaluated different process schemes for integrating oil sands, refining, and petrochemical operations and convert heavy gas oils into both refined products and petro- chemicals.

S. Laureshen; P. D. CLARK; M. P. DU PLESSIS

2006-01-01

385

Sand dams: Africa's answer to climate change?  

Microsoft Academic Search

In semi-arid regions of Africa, sand dam technology can make a significant contribution to mitigating the impacts of climate change by providing a low-cost solution to the problem of water conservation. Despite clear benefits, sand dams are used relatively little as they are very labour intensive, meaning a lack of effective community engagement can endanger project implementation and sustainability. Excellent

Simon Maddrell; Sophie Bown

386

Use of Foundry Sands in Transportation Applications.  

National Technical Information Service (NTIS)

The primary objective of this project was to verify the availability and suitability of Texas-generated foundry sand (FS) for TxDOT and to develop specifications for use of these sands in TxDOT construction and maintenance applications. Extensive literatu...

C. Vipulanandan S. Cho S. Wang

2005-01-01

387

Horizontal oil shale and tar sands retort  

Microsoft Academic Search

A horizontal retorting apparatus and method are disclosed designed to pyrolyze tar sands and oil shale, which are often found together in naturally occurring deposits. The retort is based on a horizontal retorting tube defining a horizontal retort zone having an upstream and a downstream end. Inlet means are provided for introducing the combined tar sands and oil shale into

Thomas

1982-01-01

388

RADIUM REMOVAL USING SORPTION TO FILTER SAND  

EPA Science Inventory

The study evaluated the use of a novel sand filtration process that exploits the natural capacity of filter sand to sorb radium through the use of a periodic dilute acid rinse to maintain its sorptive capacity. Batch studies were conducted to determine distribution coefficients s...

389

Sand reinforced with shredded waste tires  

SciTech Connect

The objective of this study was to investigate the feasibility of using shredded waste tires to reinforce sand. Direct shear tests were conducted on mixtures of dry sand and shredded waste tires. The following factors were studied to evaluate their influence on shear strength: normal stress, sand matrix unit weight, shred content, shred length, and shred orientation. From results of the tests, three significant factors affecting shear strength were identified: normal stress, shred content, and sand matrix unit weight. A model for estimating the strength of reinforced soils was also evaluated to determine its applicability to mixtures of sand and tire shreds. When the model is calibrated using results from one shred content, it may be useful for estimating the friction angle for other shred contents. In all cases, adding shredded tires increased the shear strength of sand, with an apparent friction angle ({phi}{prime}) as large as 67{degree} being obtained. Shred content and sand matrix unit weight were the most significant characteristics of the mixes influencing shear strength. Increasing either of these variables resulted in an increase in {phi}{prime}. Tests were also conducted on specimens consisting of only shredded tires (no sand), and the friction angle obtained was 30{degree}.

Foose, G.J.; Benson, C.H.; Bosscher, P.J. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Civil and Environmental Engineering

1996-09-01

390

Estimating Sand–Shale Formation Pore Pressure  

Microsoft Academic Search

This article presents a comprehensive evaluation method of estimating sand–shale formation pore pressure by using sonic velocity and other logging data. The method takes the influence of porosity, density, shale content, effective stress, and some other physical properties of sand–shale formation on sonic velocity into account. The influence and related logging data are combined to estimate the effective stress, and

F. Honghai; Y. Zhi; J. Rongyi

2011-01-01

391

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

392

Laboratory Experiments of Sand Ripples with Bimodal Size Distributions Under Asymmetric Oscillatory Flows  

NASA Astrophysics Data System (ADS)

The dynamics of sand ripples are vital to understanding numerous coastal processes such as sediment transport, wave attenuation, boundary layer development, and seafloor acoustic properties. Though significant laboratory research has been conducted to elucidate oscillatory flow morphodynamics under various constant and transient forcing conditions, the majority of the previous experiments were conducted only for beds with unimodal size distributions of sediment. Recent oscillatory flow experiments as well as past laboratory observations in uniform flows suggest that the presence of heterogeneous size sand compositions may significantly impact ripple morphology, resulting in a variety of observable effects (e.g., sediment sorting, bed armoring, and altered transport rates). Experimental work was conducted in a small oscillatory flow tunnel at the Sediment Dynamics Laboratory at the Naval Research Laboratory, Stennis Space Center. Three different monochromatic oscillatory forcings having velocity asymmetry were used to study sand ripple dynamics over five bimodal and two unimodal sediment beds. The seven different mixtures were composed using two unimodal sands of different colors (blue/white) and median grain diameters (d=0.31 mm / d=0.65 mm) combined into various mixtures by mass (i.e., 0/100; 10/90; 25/75; 50/50; 75/25; 90/10; and 100/0 which denotes mass percentage of blue/white sand, respectively, within each mixture). High-definition video of the sediment bed profile was acquired in conjunction with sediment trap measurements to resolve differences in ripple geometries, migration and evolution rates due to the different sediment mixtures and flow conditions. Observational findings clearly illustrate sediment stratification within ripple crests and the depth of the active mixing layer in addition to supporting sediment sorting in previous research on symmetric oscillatory flows in which the larger grains collect on top of ripple crests and smaller grains in the troughs. Preliminary quantitative results illuminate variations in equilibrium ripple geometry, ripple migration rates, and transition time scales between equilibrium states, all as functions of the sediment size mixture and flow forcing.

Calantoni, J.; Landry, B. J.

2010-12-01

393

Earth-like sand fluxes on Mars  

NASA Astrophysics Data System (ADS)

Strong and sustained winds on Mars have been considered rare, on the basis of surface meteorology measurements and global circulation models, raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process. Recent studies showed sand activity, but could not determine whether entire dunes were moving--implying large sand fluxes--or whether more localized and surficial changes had occurred. Here we present measurements of the migration rate of sand ripples and dune lee fronts at the Nili Patera dune field. We show that the dunes are near steady state, with their entire volumes composed of mobile sand. The dunes have unexpectedly high sand fluxes, similar, for example, to those in Victoria Valley, Antarctica, implying that rates of landscape modification on Mars and Earth are similar.

Bridges, N. T.; Ayoub, F.; Avouac, J.-P.; Leprince, S.; Lucas, A.; Mattson, S.

2012-05-01

394

Ecological release in White Sands lizards  

PubMed Central

Ecological opportunity is any change that allows populations to escape selection from competition and predation. After encountering ecological opportunity, populations may experience ecological release: enlarged population size, broadened resource use, and/or increased morphological variation. We identified ecological opportunity and tested for ecological release in three lizard colonists of White Sands, New Mexico (Sceloporus undulatus, Holbrookia maculata, and Aspidoscelis inornata). First, we provide evidence for ecological opportunity by demonstrating reduced species richness and abundance of potential competitors and predators at White Sands relative to nearby dark soils habitats. Second, we characterize ecological release at White Sands by demonstrating density compensation in the three White Sands lizard species and expanded resource use in White Sands S. undulatus. Contrary to predictions from ecological release models, we observed directional trait change but not increased trait variation in S. undulatus. Our results suggest that ecological opportunity and ecological release can be identified in natural populations, especially those that have recently colonized isolated ecosystems.

Roches, S Des; Robertson, J M; Harmon, L J; Rosenblum, E B

2011-01-01

395

Earth-like sand fluxes on Mars.  

PubMed

Strong and sustained winds on Mars have been considered rare, on the basis of surface meteorology measurements and global circulation models, raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process. Recent studies showed sand activity, but could not determine whether entire dunes were moving--implying large sand fluxes--or whether more localized and surficial changes had occurred. Here we present measurements of the migration rate of sand ripples and dune lee fronts at the Nili Patera dune field. We show that the dunes are near steady state, with their entire volumes composed of mobile sand. The dunes have unexpectedly high sand fluxes, similar, for example, to those in Victoria Valley, Antarctica, implying that rates of landscape modification on Mars and Earth are similar. PMID:22596156

Bridges, N T; Ayoub, F; Avouac, J-P; Leprince, S; Lucas, A; Mattson, S

2012-05-09

396

Preserving inland drift sands in the Netherlands  

NASA Astrophysics Data System (ADS)

Inland drift sands in the Netherlands are an important landscape type within the Dutch nature. They represent an important pioneer habitat which has become rare in European nature. Under current climate and environmental conditions (i.e. high N-deposition) these inland drift sands tend to be rapid colonialized by vegetation and therefor lose their aeolian activity. To maintain the area bare sand, managers regularly remove the vegetation. Lack of proper knowledge about the geomorphological processes and even more important on the geomorphological structure of these drift sands, could lead to the loss of characteristic dune structure. In an interdisciplinary research project a new management strategy was developed in which the geomorphological processes and structure form the base for the planning process. To improve the awareness of these aspects among nature managers we developed a management tool "PROMME". Several activities were taken to communicate this with the people involved in the management of drift sands like a brochure and field workshops.

Riksen, M.; Sparrius, L.; Nijssen, M.; Keestra, S.

2012-04-01

397

Decolorization of Basic Red 46 and Methylene Blue by anaerobic sludge: Biotic and abiotic processes  

Microsoft Academic Search

Decolorization of Basic Red 46 (Maxilon Red GRL) (BR46; azo dye) and Methylene Blue (MB.; cationic dye) was studied by using anaerobic sludge taken from upflow anaerobic sludge blanket bed (UASB) reactor treating wastewaters of Pakmaya Yeast Factory in Izmit, Turkey. Experiments were carried out under abiotic and biotic conditions. Abiotic tests were carried out without living biomass in order

Meltem Sarioglu; Turgay Bisgin

2010-01-01

398

Rotating fluidized bed heat exchanger  

Microsoft Academic Search

A rotating fluidized bed heat exchanger particularly adaptable as a heat exchange unit in the recuperator section of conventional gas turbine engines is disclosed comprising an annular fluidized bed, defined by inner and outer spaced apart coaxial cylindrical, perforated walls, which rotates about the longitudinal axis of the cylinders. The bed is comprised of pulverulent inert particulate material and includes

W. H. Belke; A. Goloff; G. B. Grim

1982-01-01

399

Imaging of sand production in a horizontal sand pack by X-ray computed tomography  

SciTech Connect

A laboratory experiment was performed to better understand how sand production can increase heavy oil recovery. A horizontal sand pack with an orifice at one end modeled the production of oil and sand into a perforation in a vertical well. The sand pack was scanned using X-ray computed tomography (CT). The CT images revealed that a high-porosity channel (wormhole) formed in the pack while sand was produced. The wormhole followed regions within the pack where the porosity was higher, and, consequently, the unconfined compressive strength of the sand was lower. This experiment suggests that wormholes will form within the weaker sands of a formation. The development of these high-permeability channels increases the drainage of the reservoir, which leads to higher oil recovery.

Tremblay, B.; Sedgwick, G.; Forshner, K. [Alberta Research Council, Edmonton, Alberta (Canada)

1996-06-01

400

Roller micrometer analysis of grain size and shape sorting within sand laminae from lacustrine barrier islands  

SciTech Connect

The dynamics of sand lamination deposition were investigated for two barrier islands in Lake Erie: Cedar Point Spit, Ohio, and Presque Isle, Pennsylvania. A new measurement technique, roller micrometer analysis, was used to describe the grain size and shape distributions of samples. This technique mechanically sizes grains by both the intermediate (I) and smallest (S) principal dimensions and thus divides a sample into fractions containing grains with common I and S dimensions and tabularity (S/I) ratio. Portions of the two barrier islands are subject to overwashing by wind-driven lake waters. During such events foreshore laminae are eroded and the sand is redeposited in washover fan topset and foreset laminae. At other times, normal wave activity reworks the washover fan deposits into foreshore laminae. In the transport of sand across the barrier islands from the lake margin (foreshore laminae) through the interior (fan topset laminae) and to the lagoon margin (fan foreset laminae), the following trends are observed: mean grain size increases, grain size sorting become poorer, grain size skewness becomes coarser, and, for grains of the same size, the proportion of more tabular grains decreases. These trends indicate, in a lagoonward direction, progressive winnowing from the bed load of the finer and more tabular grains and increased intermixing of the remaining coarser bed load grains. Roller micrometer analysis is an important new tool for sedimentologists. It provides traditional grain-size distribution data along with the distribution of grain tabularity. Together the two distributions are sensitive indicators of winnowing and selective deposition.

Harrell, J.A.; Braun, R.B.

1987-05-01

401

Debris-Bed Friction of Hard-Bedded Glaciers  

NASA Astrophysics Data System (ADS)

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 non-rotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if ice is Newtonian. Numerical calculations of the bed-normal drag force on a sphere in contact with a flat bed 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 200~m thick glacier sliding at 20~m a-1 with a geothermally induced melt rate of 0.006~m a-1 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.

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

2004-12-01

402

Debris-bed friction of hard-bedded glaciers  

NASA Astrophysics Data System (ADS)

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.

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

2005-06-01

403

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

404

BMM SHAKEOUT AND VIBRATING CONVEYOR TRANSPORT SAND AND CASTINGS TO ...  

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

BMM SHAKEOUT AND VIBRATING CONVEYOR TRANSPORT SAND AND CASTINGS TO SEPARATIONS SCREENS. - Southern Ductile Casting Company, Shaking, Degating & Sand Systems, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

405

Iron crystallization in a fluidized-bed Fenton process.  

PubMed

The mechanisms of iron precipitation and crystallization in a fluidized-bed reactor were investigated. Within the typical Fenton's reagent dosage and pH range, ferric ions as a product from ferrous ion oxidation would be supersaturated and would subsequently precipitate out in the form of ferric hydroxide after the initiation of the Fenton reaction. These precipitates would simultaneously crystallize onto solid particles in a fluidized-bed Fenton reactor if the precipitation proceeded toward heterogeneous nucleation. The heterogeneous crystallization rate was controlled by the fluidized material type and the aging/ripening period of the crystallites. Iron crystallization onto the construction sand was faster than onto SiO(2), although the iron removal efficiencies at 180 min, which was principally controlled by iron hydroxide solubility, were comparable. To achieve a high iron removal rate, fluidized materials have to be present at the beginning of the Fenton reaction. Organic intermediates that can form ferro-complexes, particularly volatile fatty acids, can significantly increase ferric ion solubility, hence reducing the crystallization performance. Therefore, the fluidized-bed Fenton process will achieve exceptional performance with respect to both organic pollutant removal and iron removal if it is operated with the goal of complete mineralization. Crystallized iron on the fluidized media could slightly retard the successive crystallization rate; thus, it is necessary to continuously replace a portion of the iron-coated bed with fresh media to maintain iron removal performance. The iron-coated construction sand also had a catalytic property, though was less than those of commercial goethite. PMID:21511323

Boonrattanakij, Nonglak; Lu, Ming-Chun; Anotai, Jin

2011-03-31

406

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...

407

Experimental and Engineering Support for the CAFB (Chemically Active Fluid-Bed) Demonstration: Residue Disposal/Utilization.  

National Technical Information Service (NTIS)

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...

C. H. Peterson N. H. Ulerich R. A. Newby D. L. Keairns

1984-01-01

408

Natural gas combustion in fluidised bed reactors between 600 and 850 °C: experimental study and modelling of the freeboard  

Microsoft Academic Search

In this paper, an experimental study of the natural gas–air mixture combustion in a fluidised bed containing sand particles with 350-?m mean diameter and operating at temperatures lower than the critical temperature (less than 850 °C) has been presented. A particular attention has been given to the freeboard zone where the main part of the reaction rate takes place at

S. Dounit; M. Hemati; D. Steinmetz

2001-01-01

409

The Agglomeration in the Fluidized Bed Boiler During the Co-Combustion of Biomass with Peat  

NASA Astrophysics Data System (ADS)

The formation of bed material coatings during the co-combustion of peat and biomass is caused by iron, calcium, aluminum and silicon. No signs of sodium or calcium sulfates were observed in bed material samples. Sulfates were observed in fly ash samples, when the amount of wood was 55% of the fuel mixture. Thus the bed material agglomeration during peat and biomass co-combustion is due to the partial melting of aluminosilicates, rather than the formation of low melting salts. Iron is found from the bed material coatings and may act as a flux in the melting processes of the silicates. When the agglomeration progresses, the coated sand particles are molten on the surface as seen from the increased amounts of potassium, sodium and calcium. The role of iron is not so significant in the adhesive material.

Heikkinen, Ritva E. A.; Virtanen, Mika E.; Patrikainen, H. Tapio; Laitinen, Risto S.

410

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

411

The settling dynamics of flocculating mud and sand mixtures: part 2—numerical modelling  

NASA Astrophysics Data System (ADS)

Estuarine and coastal sediment transport is characterised by the transport of both sand-sized particles (of diameter greater than 63 ?m) and muddy fine-grained sediments (silt, diameter less than 63 ?m; clay, diameter less than 2 ?m). These fractions are traditionally considered as non-cohesive and cohesive, respectively, because of the negligible physico-chemical attraction that occurs between sand grains. However, the flocculation of sediment particles is not only caused by physico-chemical attraction. Cohesivity of sediment is also caused by biology, in particular the sticky extra-cellular polymeric substances secreted by diatoms, and the effect of biology in binding sediment particles can be much larger than that of physico-chemical attraction. As demonstrated by Manning (2008) and further expanded in part 1 of this paper (Manning et al., submitted), the greater binding effect of biology allows sand particles to flocculate with mud. In many estuaries, both the sand and fine sediment fractions are transported in significant quantities. Many of the more common sediment transport modelling suites now have the capability to combine mud and sand transport. However, in all of these modelling approaches, the modelling of mixed sediment transport has still essentially separated the modelling of sand and mud fractions assuming that these different fractions do not interact except at the bed. However, the use of in situ video techniques has greatly enhanced the accuracy and reliability of settling velocity measurements and has led to a re-appraisal of this widely held assumption. Measurements of settling velocity in mixed sands presented by Manning et al. (2009) have shown strong evidence for the flocculation of mixed sediments, whilst the greater understanding of the role of biology in flocculation has identified mechanisms by which this mud-sand flocculation can occur. In the first part of this paper (Manning et al., submitted), the development of an empirical flocculation model is described which represents the interaction between sand and mud particles in the flocculation process. Measurements of the settling velocity of varying mud-sand mixtures are described, and empirical algorithms governing the variation of settling velocity with turbulence, suspended sediment concentration and mud-sand content are derived. The second part of this paper continues the theme of examination of the effects of mud-sand interaction on flocculation. A 1DV mixed transport model is developed and used to reproduce the vertical transport of mixed sediment fractions. The 1DV model is used to reproduce the measured settling velocities in the laboratory experiments described in the part 1 paper and also to reproduce measurements of concentration of mixed sediments in the Outer Thames. In both modelling exercises, the model is run using the algorithms developed in part 1 and repeated using an assumption of no interaction between mud and sand in the flocculation process. The results of the modelling show a significant improvement in the ability of the 1DV to reproduce the observed sediment behaviour when the empirical equations are used. This represents further strong evidence of the interaction between sand and mud in the flocculation process.

Spearman, Jeremy R.; Manning, Andrew J.; Whitehouse, Richard J. S.

2011-03-01

412

Method for packing chromatographic beds  

SciTech Connect

This patent describes process for packing column chromatography beds. It comprises preparing a slurry of chromatographic bed material and a liquid comprising at least one of water, methanol, chloroform and hexane, the bed material being denser than the liquid, introducing the slurry into a column provided with a removable plug at one end and allowing the slurry to settle in the column such that the bed material falls to the plugged end, thereafter centrifuging the column under the condition that the surface of the liquid is at all points and times above the surface of the bed material, with respect to the plugged end, and continuing the centrifuging for a period of time to obtain a predetermined packing level in the bed material in the substantial absence of channeling, removing the plug from the column and allowing the liquid to drain through the bed and out of the column.

Freeman, D.H.; Angeles, R.M.; Keller, S.

1991-01-15

413

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

414

Horizontal oil shale and tar sands retort  

SciTech Connect

A horizontal retorting apparatus and method are disclosed designed to pyrolyze tar sands and oil shale, which are often found together in naturally occurring deposits. The retort is based on a horizontal retorting tube defining a horizontal retort zone having an upstream and a downstream end. Inlet means are provided for introducing the combined tar sands and oil shale into the upstream end of the retort. A screw conveyor horizontally conveys tar sands and oil shale from the upstream end of the retort zone to the downstream end of the retort zone while simultaneously mixing the tar sands and oil shale to insure full release of product gases. A firebox defining a heating zone surrounds the horizontal retort is provided for heating the tar sands and oil shale to pyrolysis temperatures. Spent shale and tar sands residue are passed horizontally beneath the retort tube with any carbonaceous residue thereon being combusted to provide a portion of the heat necessary for pyrolysis. Hot waste solids resulting from combustion of spent shale and tar sands residue are also passed horizontally beneath the retort tube whereby residual heat is radiated upward to provide a portion of the pyrolysis heat. Hot gas inlet holes are provided in the retort tube so that a portion of the hot gases produced in the heating zone are passed into the retort zone for contacting and directly heating the tar sands and oil shale. Auxiliary heating means are provided to supplement the heat generated from spent shale and tar sands residue combustion in order to insure adequate pyrolysis of the raw materials with varying residual carbonaceous material.

Thomas, D.D.

1982-08-31

415

Litter ammonia generation: moisture content and organic versus inorganic bedding materials.  

PubMed

Negative impacts on the environment, bird well-being, and farm worker health indicate the need for abatement strategies for poultry litter NH(3) generation. Type of bedding affects many parameters related to poultry production including NH(3) losses. In a randomized complete block design, 3 trials compared the cumulative NH(3) volatilization for laboratory-prepared litter (4 bedding types mixed with excreta) and commercial litter (sampled from a broiler house during the second flock on reused pine wood chips). Litters were assessed at the original moisture content and 2 higher moisture contents. Broiler excrement was mixed with pine wood shavings, rice hulls, sand, and vermiculite to create litter samples. Volumetrically uniform litter samples were placed in chambers receiving humidified air where the exhaust passed through H(3)BO(3) solution, trapping litter-emitted NH(3). At the original moisture content, sand and vermiculite litters generated the most NH(3) (5.3 and 9.1 mg of N, respectively) whereas wood shavings, commercial, and rice hull litters emitted the least NH(3) (0.9-2.6 mg of N). For reducing NH(3) emissions, the results support recommendations for using wood shavings and rice hulls, already popular bedding choices in the United States and worldwide. In this research, the organic bedding materials generated the least NH(3) at the original moisture content when compared with the inorganic materials. For each bedding type, incremental increases in litter moisture content increased NH(3) volatilization. However, the effects of bedding material on NH(3) volatilization at the increased moisture levels were not clearly differentiated across the treatments. Vermiculite generated the most NH(3) (26.3 mg of N) at the highest moisture content. Vermiculite was a novel bedding choice that has a high water absorption capacity, but because of high NH(3) generation, it is not recommended for further study as broiler bedding material. Controlling unnecessary moisture inputs to broiler litter is a key to controlling NH(3) emissions. PMID:21597054

Miles, D M; Rowe, D E; Cathcart, T C

2011-06-01

416

Polishing acrylic lens materials after sand impact  

NASA Astrophysics Data System (ADS)

Commercial grade PMMA samples designed for CPV primary lens applications were subjected to sand impact in a wind tunnel. Defects caused by the impinging sand particles led to a decrease of direct transmittance and increase of haze. The observed changes increased with increasing mass and velocity of the sand deposited. Using a cotton buffing wheel it was possible to restore the PMMA surface almost back to its initial state and direct transmittance and haze back to their original values. Structural data from surface roughness measurements and SEM micrographs correlated well with the optical quantities.

Arndt, Thomas; Battenhausen, Peter; Kilian, Philipp; Sättler, Roland

2013-09-01

417

Estimation and modeling of direct rapid sand filtration for total fecal coliform removal from secondary clarifier effluents.  

PubMed

The filtration of fecal coliform from a secondary clarifier effluent was investigated using direct rapid sand filters as tertiary wastewater treatment on a pilot scale. The effect of the flocculation dose, flow loading rate, and grain size on fecal coliform removal was determined. Direct rapid sand filters can remove 0.6-1.5 log-units of fecal coliform, depending on the loading rate and grain size distribution. Meanwhile, the flocculation dose has little effect on coliform removal, and increasing the loading rate and/or grain size decreases the bacteria removal efficiency. A model was then developed for the removal process. Bacteria elimination and inactivation both in the water phase and the sand bed can be described by first-order kinetics. Removal was successfully simulated at different loading rates and grain size distributions and compared with the data obtained using pilot-scale filters. PMID:22508124

Li, Yi; Yu, Jingjing; Liu, Zhigang; Ma, Tian

2012-01-01

418

Sediment sorting along tidal sand waves: A comparison between field observations and theoretical predictions  

NASA Astrophysics Data System (ADS)

A site-by-site comparison between field observations and theoretical predictions of sediment sorting patterns along tidal sand waves is performed for ten locations in the North Sea. At each site, the observed grain size distribution along the bottom topography and the geometry of the bed forms is described in detail and the procedure used to obtain the model parameters is summarized. The model appears to accurately describe the wavelength of the observed sand waves for the majority of the locations; still providing a reliable estimate for the other sites. In addition, it is found that for seven out of the ten locations, the qualitative sorting process provided by the model agrees with the observed grain size distribution. A discussion of the site-by-site comparison is provided which, taking into account uncertainties in the field data, indicates that the model grasps the major part of the key processes controlling the phenomenon.

Van Oyen, Tomas; Blondeaux, Paolo; Van den Eynde, Dries

2013-07-01

419

Electrostatic force on saltating sand  

NASA Astrophysics Data System (ADS)

In blizzards and sandstorms, wind transport of particles is associated with separation of electrostatic charge. Moving particles develop charge of sign opposite the electrostatic charge on stationary surface particles. This electrification produces forces in addition to the gravitational and fluid friction forces that determine trajectories for particles being transported in saltation. Evaluating electrostatic forces requires the electric field strength very near the saltation surface and charge-to-mass ratios for the moving particles. In a low-level blowing sand event we measured an average charge-to-mass ratio of +60 ?C kg-1 on the saltating particles at 5-cm height and a maximum electric field of +166 kV m-1 at 1.7-cm height, in wind gusts near 12 m s-1 at 1.5-m height. The electrostatic force estimated from these measurements was equal in magnitude to the gravitational force on the saltating particles. Including electrostatic forces in the equations of motion for saltating particles may help explain discrepancies between measurements and models of saltation transport.

Schmidt, D. S.; Schmidt, R. A.; Dent, J. D.

1998-04-01

420

William River: An outstanding example of channel widening and braiding caused by bed-load addition  

NASA Astrophysics Data System (ADS)

The lower William River in northwestern Saskatchewan, Canada, presents an excellent and unambiguous example of rapid channel adjustment to abrupt additions of sandy bed load. A relatively narrow and deep single-channel stream as it flows northward to Lake Athabasca, the river picks up a 40-fold increase of bed load over a 27-km reach as it encounters a large dune field just south of the lake. As a result of the large infusion of eolian sand, the channel develops a thoroughly braided pattern while undergoing a 5-fold increase in width and a 10-fold increase in width/depth ratio.

Smith, Norman D.; Smith, Derald G.

1984-02-01

421

Depositional control on Red Clinton sandstone production, Holmes County, Ohio  

SciTech Connect

The Clinton sandstone (Silurian:Albion) is a major producing horizon throughout eastern Ohio. It accounts for 75% of total drilling activity in the state in recent years. The middle member of the Clinton, the Red, has caused problems for drillers in Holmes County, Ohio; rapid changes in thickness and porosity create wide differentials in production between closely spaced adjacent wells. A detailed analysis of Red Clinton variation in this area would be helpful for better direction of exploration and development programs. On the basis of more than 1100 drillers and geophysical logs, structural, isopach, and porosity interpretations were assembled for the Red Clinton in Holmes County. Data analysis indicates that the Red Clinton is arranged in a number of multiple bar systems trending east-west to northeast-southwest throughout the county. Production statistics show that thickness and porosity of the Red Clinton is relatively good in the cleaner bar sands, whereas thinner, finer grained, more argillaceous interbar sands yield poorer producers or dry holes. Use of this depositional model clarifies the nature of controls on directional variation in thickness and porosity in the Clinton and facilitates prediction of production trends.

Portofe, F.; Cossentino, S.; Norton, W.

1984-04-01

422

Red Fork sandstone of Oklahoma: depositional history and reservoir distribution  

SciTech Connect

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

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

1989-03-01

423

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

SciTech Connect

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 [approximately]4 [times] 10[sup 8] 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. 45 refs., 9 figs.

Shonnard, D.R.; Taylor, R.T.; Hanna, M.L.; Boro, C.O.; Duba, A.G. (Lawrence Livermore National Lab., CA (United States))

1994-01-01

424

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 withdra