Science.gov

Sample records for red sand beds

  1. White Sands, Carrizozo Lava Beds, NM

    NASA Technical Reports Server (NTRS)

    1973-01-01

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

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

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

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

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

    USGS Publications Warehouse

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

    2007-01-01

    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

  4. Different bed surface and flow resistance characteristics for gravel and sand bed

    NASA Astrophysics Data System (ADS)

    Fan, N.; Yang, K.; Nie, R.; Liu, X.

    2014-12-01

    Bed forms affect both bed load transport and flow resistance strongly and change their shapes and sizes depending on underlying grain size distribution and shear stress. A series of flume experiments were conducted at the Saint Anthony Falls Laboratory to study the effect of bed form dynamics on flow turbulence and sediment transport with both gravel and sand as bed material and different flow conditions. From the experimental data, the spectrum of bed elevation time series, the PDFs of bed elevation increments and the flow resistance characteristics are all analyzed. The wavelet-based spectral analysis shows that the slopes of the elevation spectrums are -2 and -3 for gravel and sand bed surfaces, respectively. The slope -3 indicates that the surface is self-similar, in another words, the ratios of bed form heights and lengths for different bed forms are the same; however, the slope of -2 indicates that the surface is self-affine, and in such case (-2) the ratios of bed form heights and lengths for different bed forms are not correlated at all. We interpret that the relative size of grain and boundary layer affects the bed form characteristics significantly, e.g., grain size of sand is of the same scale as the thickness of boundary layer, but both are much smaller than the grain size of gravel. Our results suggest that the PDFs of bed elevation increments for both gravel and sand beds can be fitted well with two-sided asymmetric exponential function. Furthermore, we show that the flow resistance (Darcy-Weisbach coefficients f) are much higher for sand bed than gravel bed, and the former is contributed by form drags, which is much larger than grain drags. For gravel bed, f and the skewness of bed elevation increments increases with flow discharge whereas for the sand bed, both f and the skewness of bed elevation increments decreases which corresponds to the transition in hydraulic conditions for dune to dynamic flat surface in our experiments. The analysis

  5. Erosion of sand from a gravel bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cleaning of fine sediment out of gravel stream beds has become an important method to restore impacted stream habitats. Introducing the increased flows needed to entrain fine sediments without eroding the coarser fractions of the bed and potentially destroying its usefulness as a habitat requires c...

  6. Erosion depth of sand from an immobile gravel bed

    NASA Astrophysics Data System (ADS)

    Kuhnle, R.; Wren, D.; Langendoen, E.

    2015-03-01

    This study was conducted to improve prediction of the depth of erosion of sand (D50 = 0.3-0.9 mm) from immobile gravel (D50 = 36.1 mm) under steady uniform flows with bed shear stresses from 0.1 to 0.9 of that required to entrain the gravel. This situation, often encountered downstream of dams, has important implications for habitat restoration. Steady uniform flows were imposed on a flume channel containing a mixture of sand and gravel until sediment concentrations in the flow exiting the channel became small. The elevation of sand relative to gravel was measured after each experiment and compared poorly to calculated depths from published relationships whose predictions were based in part on the equivalent grain roughness of the bed. An improved predictive relationship was developed by using the cumulative distribution function of the surface gravel elevations to scale the shear velocity available for transporting sand from the gravel substrate.

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

    USGS Publications Warehouse

    Wright, S.; Parker, G.

    2005-01-01

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

  8. Erosion depth of sand from an immobile gravel bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abstract This study was conducted to provide information on the depth of erosion of sand (D50 = 0.3, 0.9 mm) from immobile gravel (D50 = 36.1 mm) under steady uniform flows with bed shear stresses from 0.1 to 0.9 of that required to entrain the gravel. This situation, often encountered downstream o...

  9. Sand Bed Morphodynamics under Standing Waves and Vegetated Conditions

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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

  10. Cross-channel patterns of bed material transport in a poorly sorted sand-bed channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2016-11-01

    Understanding of sediment transport comes largely from studies conducted on well-sorted sand-bed and poorly sorted gravel-bed channels. The aim of this study is to evaluate cross-channel patterns of transport rate and grain size in a poorly sorted sand-bed channel. Transport observations were collected from the San Antonio River using a Helley-Smith sampler during flows from 0.02 to 1.1 times bankfull capacity. Resulting transport rates and grain size distributions were pooled to describe eight sections across a channel transect that includes the lower bank and compared to local boundary material. Maximum transport rates are concentrated in the central zone of the streambed regardless of flow level, but gravels and coarse sands are conveyed preferentially on one side of the bed. Grain size distributions change relatively little with flow and approximate the local bed material supply. The size distributions associated with smaller transport rates near the channel margin become finer and more closely approximate the size characteristics of bank material at higher flows. Results extend patterns of differential routing of grain sizes to channel banks and establish the relative fluxes between the bed and bank environments. The small gravel content in poorly sorted sand beds requires further attention because it can contribute to cross-channel variation in sediment fluxes, limit the development of sandy bedforms, and influence the quality of streambed habitat.

  11. Predicting bed load transport of sand and gravel on Goodwin Creek

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bed load transport rates are difficult to predict in channels with bed material composed of sand and gravel mixtures. The transport of bed load was measured on Goodwin Creek, and in a laboratory flume channel with a similar bed material size distribution. The range of bed load transport rates meas...

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

    USGS Publications Warehouse

    Gaeuman, D.; Jacobson, R.B.

    2006-01-01

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

  13. Centerline Bed Elevation Profile of Sand Bed Channel due to Bar Formation

    NASA Astrophysics Data System (ADS)

    Tholibon, D. A.; Ariffin, J.; Abdullah, J.; Muhamad, N. S.

    2016-07-01

    Numerous data on bar formation have been accumulated yet the methods to predict bar geometry especially bar height are still insufficient. Objectives of this study to determine the trend in term of a significant difference of centreline bed elevation profile along the longitudinal distance. This can be investigate by carried out an experimental work in an erodible sand bed channel using a large-scale physical river model. The study included the various hydraulic characteristics with steady flow rates and sediment supply. An experimental work consists of four matrices of flow rate and channel width with other variables namely grains size and bed slope were kept constant. Analysis have included the discussion on a significant difference of centreline bed elevation profile along the longitudinal distance. As a conclusion the higher velocity in the smaller channel width have induced erosion of the banks that resulted in elevation increase while the larger flow rates have contributed to higher elevation.

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

    PubMed

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

    2001-01-01

    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.

  15. Mineral magnetic characteristics of the late Quaternary coastal red sands of Bheemuni, East Coast (India)

    NASA Astrophysics Data System (ADS)

    Srivastava, Priyeshu; Sangode, S. J.; Parmar, Nikita; Meshram, D. C.; Jadhav, Priyanka; Singhvi, A. K.

    2016-11-01

    The voluminous red sand deposits of Bheemuni in the east coast of India provide record of coastal land-sea interaction during the late Quaternary climatic and eustatic oscillations. Limited information on the origin and depositional environments of these red sands and their chronology is available. We studied two inland to coast cross profiles from Bheemuni red sand deposits using mineral magnetism, color characteristics and Citrate-bicarbonate-dithionite (CBD) extractable pedogenic iron oxides over 23 horizons along with optically stimulated luminescence (OSL) chronology at 6 horizons. The oldest exposed bed had an optical age of 48.9 ± 1.7 ka. Differential ages between the two parallel sections (SOS = 48.9 ± 1.7 to 12.1 ± 0.3 ka and IMD = 29.3 ± 3.5 ka) suggest laterally shifting fluvial sedimentation. Both the profiles show significant amount of antiferromagnetic oxide (hematite) along with ferrimagnetic (magnetite/maghemite) mineral composition. The granulometric (/domain-) sensitive parameters (χFD, χARM, SIRM/χLF and χARM/χLF) indicate variable concentration of superparamagnetic (SP) and single domain (SD) particles between the two profiles. The higher frequency dependent and pedogenic magnetic susceptibilities (χFD and χpedo) in the younger (IMD) profile suggest enhanced pedogenesis under a warm-wet climate post 29.3 ka and also during Holocene. A combination of hard isothermal remanent magnetization (HIRM) and redness rating (RR) index indicates distinct but variable concentration of a) crystalline and b) poorly crystalline (pigmentary) hematites in both the profiles. We consider that the former (#a) is derived from hinterland red soils and possibly due to post-depositional diagenesis, and the latter (#b) precipitated from the dissolved iron under fluvial regime imparting the unique red coloration to Bheemuni sands. Partial to complete alteration of ferromagnesian minerals due to pedogenesis in hinterlands under warm-wet climate was therefore the

  16. Density stratification effects in sand-bed rivers

    USGS Publications Warehouse

    Wright, S.; Parker, G.

    2004-01-01

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

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

    PubMed

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

    2014-03-11

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

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

    USGS Publications Warehouse

    Wright, S.; Parker, G.

    2004-01-01

    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.

  19. Bed topography and sand transport responses to a step change in discharge and water depth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ephemeral streams with sand and gravel beds may inherit bed topography caused by previous flow events, resulting in bed topography that is not in equilibrium with flow conditions, complicating the modeling of flow and sediment transport. Major flow events, resulting from rainfall with high intensity...

  20. Australian Red Dune Sand: A Potential Martian Regolith Analog

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  1. Sensitivity of growth characteristics of tidal sand ridges and long bed waves to formulations of bed shear stress, sand transport and tidal forcing: A numerical model study

    NASA Astrophysics Data System (ADS)

    Yuan, Bing; de Swart, Huib E.; Panadès, Carles

    2016-09-01

    Tidal sand ridges and long bed waves are large-scale bedforms that are observed on continental shelves. They differ in their wavelength and in their orientation with respect to the principal direction of tidal currents. Previous studies indicate that tidal sand ridges appear in areas where tidal currents are above 0.5 m s-1, while long bed waves occur in regions where the maximum tidal current velocity is slightly above the critical velocity for sand erosion and the current is elliptical. An idealized nonlinear numerical model was developed to improve the understanding of the initial formation of these bedforms. The model governs the feedbacks between tidally forced depth-averaged currents and the sandy bed on the outer shelf. The effects of different formulations of bed shear stress and sand transport, tidal ellipticity and different tidal constituents on the characteristics of these bedforms (growth rate, wavelength, orientation of the preferred bedforms) during their initial formation were examined systematically. The results show that the formulations for bed shear stress and slope-induced sand transport are not critical for the initial formation of these bedforms. For tidal sand ridges, under rectilinear tidal currents, increasing the critical bed shear stress for sand erosion decreases the growth rate and the wavelength of the preferred bedforms significantly, while the orientation angle slightly decreases. The dependence of the growth rate, wavelength and the orientation of the preferred bedforms on the tidal ellipticity is non-monotonic. A decrease in tidal frequency results in preferred bedforms with larger wavelength and smaller orientation angle, while their growth rate hardly changes. In the case of joint diurnal and semidiurnal tides, or spring-neap tides, the characteristics of the bedforms are determined by the dominant tidal constituent. For long bed waves, the number of anticyclonically/cyclonically oriented bedforms with respect to the principal

  2. Use of sand beds of variable permeability in beach profile engineering

    NASA Astrophysics Data System (ADS)

    Heitor Reis, A.; Gama, Cristina

    2010-05-01

    Here we present a technique based on theoretical grounds for dealing with beachface dynamics in response to wave forcing. Previous work has provided a relationship involving mean sand grain size, wave height, and beachface slope for a broad range of Iribarren number. The key aspect of beach morphodynamics was shown to be the permeability of the sand bed, which may be correlated to sand grain size and sphericity, and bed porosity, through the Kozeny-Cárman equation. Therefore, we show how beach nourishment aiming at beach profile recovering must be carried out with the use of sand beds of appropriate mean grain size. The theory also illuminates beach dynamics, namely the reshaping of sandy beachfaces in response to changes in wave height.

  3. Effect of sand and wood-shavings bedding on the behavior of broiler chickens.

    PubMed

    Shields, S J; Garner, J P; Mench, J A

    2005-12-01

    The purpose of this study was to determine the effect of 2 different bedding types, sand and wood shavings, on the behavior of broiler chickens. In experiment 1, 6 pens were divided down the center and bedded half with sand and half with wood shavings. Male broilers (10/pen) were observed by scan sampling at 5- or 12-min intervals throughout the 6-wk growth period during the morning (between 0800 to 0900 h), afternoon (1200 to 1500 h), and night (2300 to 0600 h). There was a significant behavior x substrate x week interaction during the day (P < 0.0001) and at night (P < 0.0002). Drinking, dustbathing, preening, and sitting increased in frequency on the sand side but decreased on the wood shavings side during the day, as did resting at night. In general, broilers performed a greater proportion of their total behavioral time budget on the sand (P < 0.0001) as they aged. Broilers used the divider between the 2 bedding types to perch; perching behavior peaked during wk 4. In experiment 2, male broilers were housed in 8 pens (50 birds/pen) bedded only in sand or wood shavings. Bedding type had no effect on behavioral time budgets (P = 0.8946), although there were age-related changes in behavior on both bedding types. These results indicate that when given a choice, broilers increasingly performed many of their behaviors on sand, but if only one bedding type was provided they performed those behaviors with similar frequency on sand or wood shavings.

  4. Turbulent flow and sand transport over a cobble bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The turbulence structure of flow over rough beds and its interaction with fine sediments in the bed are important for 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  6. Measurement of bedload transport in sand-bed rivers: a look at two indirect sampling methods

    USGS Publications Warehouse

    Holmes, Robert R.; Gray, John R.; Laronne, Jonathan B.; Marr, Jeffrey D.G.

    2010-01-01

    Sand-bed rivers present unique challenges to accurate measurement of the bedload transport rate using the traditional direct sampling methods of direct traps (for example the Helley-Smith bedload sampler). The two major issues are: 1) over sampling of sand transport caused by “mining” of sand due to the flow disturbance induced by the presence of the sampler and 2) clogging of the mesh bag with sand particles reducing the hydraulic efficiency of the sampler. Indirect measurement methods hold promise in that unlike direct methods, no transport-altering flow disturbance near the bed occurs. The bedform velocimetry method utilizes a measure of the bedform geometry and the speed of bedform translation to estimate the bedload transport through mass balance. The bedform velocimetry method is readily applied for the estimation of bedload transport in large sand-bed rivers so long as prominent bedforms are present and the streamflow discharge is steady for long enough to provide sufficient bedform translation between the successive bathymetric data sets. Bedform velocimetry in small sandbed rivers is often problematic due to rapid variation within the hydrograph. The bottom-track bias feature of the acoustic Doppler current profiler (ADCP) has been utilized to accurately estimate the virtual velocities of sand-bed rivers. Coupling measurement of the virtual velocity with an accurate determination of the active depth of the streambed sediment movement is another method to measure bedload transport, which will be termed the “virtual velocity” method. Much research remains to develop methods and determine accuracy of the virtual velocity method in small sand-bed rivers.

  7. Flow and sand transport over an immobile gravel bed.

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. Sand infiltration into a gravel bed: A mathematical model

    NASA Astrophysics Data System (ADS)

    Herrero, A.; Berni, C.

    2016-11-01

    Fine sediment infiltration into a river bed is a physical process affected by different human actions and has several environmental, socioeconomic, and river morphology consequences. A theoretical model is proposed herein aiming to reproduce the fine sediment content depth profile resulting from the infiltration of fine sediment into an initially clean gravel bed. The model is based on the probability of infiltrating particles to be trapped in a pore throat formed by three bed particles. The model is tested against previous experimental results and is found to reproduce adequately the occurrence of the two infiltration mechanisms reported by previous studies: bridging and unimpeded static percolation. Theoretical depth profiles are found to underestimate fine sediment content at the bed subsurface (below 2-3 gravel diameter depth) compared to the laboratory results. This may be due to hyporheic flow that is not taken into account in our model. In flow experiments, the particles previously infiltrated and deposited might be destabilized by pore water flow and their fall down to the bed might be magnified.

  9. Acoustic observations of near-bed sediment concentration and flux statistics above migrating sand dunes

    NASA Astrophysics Data System (ADS)

    Wilson, G. W.; Hay, A. E.

    2016-06-01

    A coherent Doppler profiler was used to measure coincident time series of velocity (u,w), sediment mass concentration (c), and sediment grain size (d), above mobile sand dunes in unidirectional flow (˜1 m/s, ˜1 m water depth). The measurements are used to extract statistical distributions of sediment concentration and flux just above the bed. Observed mass fluxes (uc,wc) were well fit by quasi-exponential distributions, at all positions along the dune profile, similar to previous observations of single-particle momenta for bed load over flat beds. Observed concentrations of moving particles were well fit by negative-binomial distributions, also similar to previous observations over flat beds. These probability distributions relate to two recent stochastic theories, previously derived and verified for uniform flow over flat beds. It is hypothesized that these theories may also be used as a local approximation in natural-scale flows with bed forms.

  10. Risk of Mycoplasma bovis transmission from contaminated sand bedding to naive dairy calves.

    PubMed

    Wilson, D J; Justice-Allen, A; Goodell, G; Baldwin, T J; Skirpstunas, R T; Cavender, K B

    2011-03-01

    The objective of this study was to evaluate the possible transmission of Mycoplasma bovis from positive sand bedding to naïve dairy calves. Twelve preweaned Holstein bull calves were blocked in pairs and randomly assigned as unexposed controls (n=6) bedded with control sand, or exposed calves (n=6) bedded with sand previously positive for M. bovis at a dairy farm. Bedding sand was cultured weekly. Nasal and ear swabs and sera were collected weekly, tracheal swabs were collected monthly, and by the end of the 105-d study, all calves were euthanized (n=10) or died (n=2). Sera were tested for M. bovis-specific antibody. Mycoplasma spp. culture was performed on nasal and ear swabs; culture and a PCR differentiating multiple Mycoplasma spp. were performed on postmortem samples of lung, retropharyngeal lymph node, and trachea from each calf. A complete necropsy also was performed. During 6 wk, mycoplasma concentration in exposed group sand was between 200 and 32,000 cfu/g. All 166 tracheal swabs, nasal and ear swabs, and postmortem tests from all calves were negative for mycoplasma. All 94 sera were negative for M. bovis-specific antibody. No gross pathology suggestive of mycoplasma disease was detected. The probability of mycoplasma detection, if an exposed calf had become infected 4 wk after exposure, ranged between 97 and 99% depending on time of exposure for individual calves. There was no evidence that sand bedding contaminated with M. bovis might serve as a source of transmission to naïve dairy calves.

  11. Simple stochastic cellular automaton model for starved beds and implications about formation of sand topographic features in terms of sand flux

    NASA Astrophysics Data System (ADS)

    Endo, Noritaka

    2016-12-01

    A simple stochastic cellular automaton model is proposed for simulating bedload transport, especially for cases with a low transport rate and where available sediments are very sparse on substrates in a subaqueous system. Numerical simulations show that the bed type changes from sheet flow through sand patches to ripples as the amount of sand increases; this is consistent with observations in flume experiments and in the field. Without changes in external conditions, the sand flux calculated for a given amount of sand decreases over time as bedforms develop from a flat bed. This appears to be inconsistent with the general understanding that sand flux remains unchanged under the constant-fluid condition, but it is consistent with the previous experimental data. For areas of low sand abundance, the sand flux versus sand amount (flux-density relation) in the simulation shows a single peak with an abrupt decrease, followed by a long tail; this is very similar to the flux-density relation seen in automobile traffic flow. This pattern (the relation between segments of the curve and the corresponding bed states) suggests that sand sheets, sand patches, and sand ripples correspond respectively to the free-flow phase, congested phase, and jam phase of traffic flows. This implies that sand topographic features on starved beds are determined by the degree of interference between sand particles. Although the present study deals with simple cases only, this can provide a simplified but effective modeling of the more complicated sediment transport processes controlled by interference due to contact between grains, such as the pulsatory migration of grain-size bimodal mixtures with repetition of clustering and scattering.

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

    NASA Astrophysics Data System (ADS)

    Mikuláš, Radek; Skupien, Petr; Bubík, Miroslav; Vašíček, Zdeněk

    2009-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Topping, David J.; Rubin, David M.; Nelson, Jonathan M.; Kinzel, Paul J.; Corson, Ingrid C.

    2000-02-01

    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

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

    USGS Publications Warehouse

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

    2000-01-01

    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

  15. Survival and replication of Mycoplasma species in recycled bedding sand and association with mastitis on dairy farms in Utah.

    PubMed

    Justice-Allen, A; Trujillo, J; Corbett, R; Harding, R; Goodell, G; Wilson, D

    2010-01-01

    Mycoplasma spp., usually Mycoplasma bovis, are important bovine pathogens that can cause mastitis, metritis, pneumonia, and arthritis. The currently documented routes of transmission of Mycoplasma spp. are through contaminated milking equipment and by direct animal contact. The existence of environmental sources for Mycoplasma spp. and their role in transmission and clinical disease is poorly characterized. Mycoplasma spp. (confirmed as M. bovis in 2 of 4 samples tested using PCR) was found in recycled bedding sand originating from a dairy experiencing an outbreak of clinical mycoplasma mastitis. Mycoplasma spp. were subsequently found in bedding sand from 2 other dairies whose bulk-tank milk was mycoplasma-positive. The association between the occurrence of Mycoplasma spp. in recycled bedding sand and mycoplasma mastitis in cows was further investigated using a pile of recycled sand from dairy 1. Study objectives included the determination of factors associated with the concentration of Mycoplasma spp. in recycled bedding sand and the duration of survival of mycoplasmas in the sand. We also evaluated the efficacy of 2 disinfectants at 2 different concentrations each for the elimination of Mycoplasma spp. from contaminated sand. Mycoplasma spp. survived in the sand pile for 8 mo. The concentration of Mycoplasma spp. within the sand pile was directly related to temperature and precipitation. It was also positively associated with the growth of gram-negative microorganisms, suggesting the possibility of the formation of a biofilm. Ideal temperatures for replication of Mycoplasma spp. occurred between 15 and 20 degrees C. Moisture in the sand and movement of the sand pile also appeared to play a role in replication of mycoplasmas. We found that 0.5% sodium hypochlorite or 2% chlorhexidine were efficacious in eliminating Mycoplasma spp. from contaminated bedding sand. Recycled bedding sand could be an environmental source of Mycoplasma spp., including M. bovis

  16. Bacterial counts on teat skin and in new sand, recycled sand, and recycled manure solids used as bedding in freestalls.

    PubMed

    Rowbotham, R F; Ruegg, P L

    2016-08-01

    On modern dairy farms, environmental mastitis pathogens are usually the predominant cause of mastitis, and bedding often serves as a point of exposure to these organisms. The objective of this longitudinal study was to determine bacterial populations of 4 different bedding types [deep-bedded new sand (NES), deep-bedded recycled sand (RS), deep-bedded manure solids (DBMS), and shallow-bedded manure solids over foam core mattresses (SBMS)] and of teat skin swabs of primarily primiparous cows housed in a single facility over all 4 seasons. Samples of bedding were collected weekly (n=49wk) from pens that each contained 32 lactating dairy cows. Throughout the length of the same period, composite swabs of teat skin were collected weekly from all cows before and after premilking teat sanitation. Median numbers of streptococci and streptococci-like organisms (SSLO) were >8.6×10(6) cfu/g and >6.9×10(3) cfu/teat swab for all bedding types and teat swabs, respectively. Numbers of SSLO were greatest in samples of SBMS (2.1×10(8) cfu/g) and least in samples of NES (8.6×10(6) cfu/g), RS (1.3×10(7) cfu/g), and DBMS (1.7×10(7) cfu/g). Numbers of gram-negative bacteria in bedding (5.5×10(4) to 1.2×10(7) cfu/g) were fewer than numbers of SSLO (8.6×10(6) to 2.1×10(8) cfu/g). Numbers of coliform bacteria were greatest in samples of DBMS (2.2×10(6) cfu/g) and least in samples of NES (3.6×10(3) cfu/g). In general, the relative number of bacteria on teat skin corresponded to exposure in bedding. Numbers of gram-negative bacteria recovered from prepreparation teat swabs were greatest for cows bedded with DBMS (1.0×10(4) cfu/swab) and RS (2.5×10(3) cfu/swab) and least for cows bedded with NES (5.8×10(2) cfu/swab). Median numbers of coliform and Klebsiella spp. recovered from prepreparation teat swabs were below the limit of detection for all cows except those bedded with DBMS. Numbers of SSLO recovered from prepreparation teat swabs were least for cows bedded with DBMS (6.9

  17. Effects of sand and straw bedding on the lying behavior, cleanliness, and hoof and hock injuries of dairy cows.

    PubMed

    Norring, M; Manninen, E; de Passillé, A M; Rushen, J; Munksgaard, L; Saloniemi, H

    2008-02-01

    This experiment compared the effects of sand and straw bedding in free stalls on resting time, cleanliness, hock injuries, and hoof health of dairy cows and tested whether cow preferences for a bedding material depended on the familiarity with the material. A total of 52 dairy cows were kept either on straw bedded concrete stalls or sand stalls for at least 21 wk. The lying behavior was observed, and hock lesions, hoof health, and cleanliness of the cows and stalls were measured. A 5-d preference test between sand and straw stalls was conducted at the end of the experiment. The total daily duration of lying was longer for cows on straw bedding than on sand bedding (straw 749 +/- 16 vs. sand 678 +/- 19 min). During the preference test, cows that had been kept on straw bedding preferred lying in straw stalls [straw 218.7 (133.4 to 239.7) vs. sand 9.0 min (2.8 to 44.8)]; however, cows that had been kept on sand showed no preference [straw 101.3 (51.7 to 205.9) vs. sand 94.3 min (54.1 to 156.1, median and interquartile range)]. Although there were no differences in the dirtiness of stalls, the cows using straw stalls were dirtier than cows using sand stalls [straw 6.04 (5.39 to 6.28) vs. sand 4.19 (3.62 to 5.16)]. At the end of experiment the severity of hock lesions was lower for cows on sand than for cows on straw [sand 0.5 (0.0 to 1.0) vs. straw 1.0 (1.0 to 2.0)]. The improvement in overall hoof health over the observation period was greater for cows kept on sand compared with cows kept on straw [sand -2.00 (-3.75 to -0.25) vs. straw 0.00 (-2.00 to 2.00)]. Straw bedding increased the time that cows spend lying, and cows preferred straw stalls to sand stalls. However, previous experience with sand reduces avoidance of sand stalls. Sand stalls were advantageous for cow cleanliness and health; hock lesions and claw diseases healed more quickly for cows using sand stalls compared with straw.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    1999-09-01

    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

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

    USGS Publications Warehouse

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

    2007-01-01

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

  1. Fecal Indicator Bacteria Entrainment from Streambed to Water Column: Transport by Unsteady Flow over a Sand Bed.

    PubMed

    Surbeck, Cristiane Q; Douglas Shields, F; Cooper, Alexandra M

    2016-05-01

    Storms cause a substantial increase in the fecal indicator bacteria (FIB) concentrations in stream water as a result of FIB-laden runoff and the release of FIB from stream sediments. Previous work has emphasized the association between FIB and bed sediments finer than sand. The objectives of this work were to elucidate the effect of various velocities on the entrainment of bed-dwelling coliforms in sand-bed streams and to refine methodologies for quantifying sandy streambeds as sources of FIB. Pump-induced hydrographs were created using a stainless steel nonrecirculating flume. Experiments consisted of simulating four storm hydrographs and collecting water samples upstream and downstream of a sand bed at selected intervals. Bed sediment samples were collected before and after each event. The highest concentrations of total coliform and suspended sediments generally occurred in the downstream samples during the rising limb of the hydrographs as a result of entrainment of coliforms and sand from the bed to the water column. There was a first flush effect in the system, as the upper layer of sand was influenced by a rapidly increasing velocity at ∼0.2 m s. Coliforms downstream of the sand bed increased rapidly as velocity exceeded this threshold but then declined even as velocity and discharge continued to increase. This likely reflects the depletion of coliforms as the more densely populated sediment layer was flushed out. There is evidence that streams with sand beds harbor enough FIB that development of total maximum daily loads (TMDLs) should include consideration of them as a source.

  2. Exploring the Relationship Between Hydrograph Characteristics and the Time Evolution of Sand Bed Morphology

    NASA Astrophysics Data System (ADS)

    Ockelford, A.; Parsons, D. R.; Hardy, R. J.; Ashworth, P. J.; Best, J.

    2015-12-01

    The development of sand bed morphology in response to steady flow is adequately described in most bedform phase diagrams. This includes the prediction of bedform wavelength, height and shape, all important parameters in estimating flow resistance. However, during time-varying flow, such as that experienced during the passage of a flood wave, the implicit assumption that bedform adjustment tracks changes in flow depth and velocity does not hold true due to bedform hysteresis. Consequently, there is a need to understand which characteristics of unsteady flow drive the disequilibrium dynamics between bedform geometry and hydraulic conditions. This paper describes a series of experiments designed to identify the impacts of hydrograph characteristics on the morphodynamic evolution of alluvial dunes. Mobile sand bed (D50 of 450μm) experiments were undertaken in a 16m long, 1.6m wide flume. Sediment was water worked under steady unidirectional flow until equilibrium bed conditions were achieved, after which a hydrograph was applied. At the end of the hydrograph, a period of steady flow was once again run until equilibrium conditions were attained. Hydrograph one consisted of steeply rising (80 minutes) and falling (65 minutes) limbs with hydrograph two characterised by longer rising (170 minutes) and falling (230 minutes) limbs. During the hydrograph discharge was changed in discrete steps. Bed morphology profiles were measured continuously along a 5m by 0.6m, centreline transect using twelve ultrasonic sensors. Three-dimensional flow was measured with a stack of Acoustic Doppler Velocimeters downstream of the transect. Suspended sediment was quantified using a three-frequency set of Acoustic Backscatter Sensors. The impact of these differing hydrograph characteristics are discussed in terms of differences between equilibrium bed morphologies, evolving flow field characteristics and the dynamics of suspended sediment concentrations through the hydrographs.

  3. Pyrolysis of Uinta Basin Oil Sands in fluidized bed and rotary kiln reactors

    SciTech Connect

    Nagpal, S.; Fletcher, J.V.; Hanson, F.V.

    1995-12-31

    A pilot-scale fluidized bed reactor (FBR) was used to pyrolyze the mined and crushed ore from the PR Spring oil sands deposit which is located in the Uinta Basin of Utah. Liquid yields of approximately 80 wt% of the bitumen fed to the reactor were obtained. This compares to 55-70 wt% obtained from smaller laboratory scale fluidized bed reactors and a pilot-scale rotary kiln. The product yields and distributions exhibited no discernable trends with reactor temperature or solids retention time. The liquid products obtained from the pilot-scale fluidized bed reactor were upgraded compared to the bitumen in terms of volatility, viscosity, molecular weight, and metals (Ni and V) content. The nitrogen and sulphur contents of the total liquid products were also reduced relative to the bitumen. A comparison of oil sands pyrolysis yields from a pilot scale FBR and a rotary kiln of the same diameter (15.2 cm) was made. Under similar pyrolysis conditions, the rotary kiln produced a slightly more upgraded product but at lower total liquid yields. Kinetic modeling of the various reactors indicates that the pilot-scale FBR product distributions may be explained using a simplified two-reaction scheme. It is proposed that secondary cracking is suppressed in the large diameter FBR due to elimination of slugging and the superior quality of fluidization in the reactor. More experimental studies with the rotary kiln and an economic evaluation will be required before concluding which reactor is preferred for the thermal recovery process.

  4. Bedform dynamics in a large sand-bedded river using multibeam echo sounding

    NASA Astrophysics Data System (ADS)

    Elliott, C. M.; Jacobson, R. B.; Erwin, S.; Eric, A. B.; DeLonay, A. J.

    2014-12-01

    High-resolution repeat multibeam Echo Sounder (MBES) surveys of the Lower Missouri River in Missouri, USA demonstrate sand bedform movement at a variety of scales over a range of discharges. Understanding dune transport rates and the temporal and spatial variability in sizes across the channel has implications for how sediment transport measurements are made and for understanding the dynamics of habitats utilized by benthic organisms over a range of life stages. Nearly 800 miles of the Lower Missouri River has been altered through channelization and bank stabilization that began in the early 1900's for navigation purposes. Channelization of the Lower Missouri River has created a self-scouring navigation channel with large dunes that migrate downstream over a wide range of discharges. Until the use of MBES surveys on the Missouri River the spatial variability of dune forms in the Missouri River navigation channel was poorly understood. MBES surveys allow for visualization of a range of sand bedforms and repeat measurements demonstrate that dunes are moving over a wide range of discharges on the river. Understanding the spatial variability of dunes and dune movement across the channel and in different channel settings (bends, channel cross-overs, near channel structures) will inform emerging methods in sediment transport measurement that use bedform differencing calculations and provide context for physical bedload sediment sampling on large sand-bedded rivers. Multiple benthic fish species of interest including the endangered pallid sturgeon utilize Missouri River dune fields and adjacent regions for migration, feeding, spawning, early development and dispersal. Surveys using MBES and other hydroacoustic tools provide fisheries biologists with broad new insights into the functionality of bedforms as habitat for critical life stages of large river fish species in the Missouri River, and similar sand-bedded systems.

  5. [Experimental study of the red-bed pigment with diffuse reflectance spectroscopy].

    PubMed

    Jiang, Lian-Ting; Chen, Guo-Neng; Peng, Zhuo-Lun

    2013-10-01

    Red pigment of continental red-bed is known originating from the fine-particle hematite in the rocks. Advance of researches on the origin of continental red-bed demonstrates that the red pigment of red-bed originated from its diagenetic but not depositional process. The high diagenetic temperature causes the dehydration of iron hydrate to form hematite, generating the red pigment. For examining the above hypothesis, the authors of this paper designed an experiment to approach the reddening process, i.e. formation of the red pigment of continental red-bed. Black ooze sampled from the Holocene sediments of the Pearl River Delta was heated in different ways. The diffuse reflectance spectroscopy (DRS) of those heated ooze samples were detected with Perkin-Elmer Lamdba 950 ultraviolet/visible/near-infrared spectrophotometer, and moreover, red-values of the samples were calculated for determining their coloring levels. Iron in black ooze sediment is predominantly in the form of goethite. Experimental results verified that initial dehydration-temperature of goethite is about 150 degrees C, either enhancing temperature or prolonging heating time is accompanied with decreasing goethite and increasing hematite, and a positive relationship exists between red-value of samples and peak-height of hematite. The experimental results strongly support the idea of thermal origin of continental red-bed.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Recent laboratory experiments and field measurements have shown that small quantities of cohesive clay, and in particular 'sticky' biological polymers, within a sandy substrate dramatically reduce the development rate of sedimentary bedforms, with major implications for sediment transport rate calculations and process interpretations from the sedimentary record. FURTHER INFORMATION Flow and sediment transport predictions from sedimentary structures found in modern estuaries and within estuarine geological systems are impeded by an almost complete lack of process-based knowledge of the behaviour of natural sediments that consist of mixtures of cohesionless sand and biologically-active cohesive mud. Indeed, existing predictive models are largely based on non-organic cohesionless sands, despite the fact that mud, in pure form or mixed with sand, is the most common sediment on Earth and also the most biologically active interface across a range of Earth-surface environments, including rivers and shallow seas. The multidisciplinary COHBED project uses state-of-the-art laboratory and field technologies to measure the erosional properties of mixed cohesive sediment beds and the formation and stability of sedimentary bedforms on these beds, integrating the key physical and biological processes that govern bed evolution. The development of current ripples on cohesive mixed sediment beds was investigated as a function of physical control on bed cohesion versus biological control on bed cohesion. These investigations included laboratory flume experiments in the Hydrodynamics Laboratory (Bangor University) and field experiments in the Dee estuary (at West Kirby near Liverpool). The flume experiments showed that winnowing of fine-grained cohesive sediment, including biological stabilisers, is an important process affecting the development rate, size and shape of the cohesive bedforms. The ripples developed progressively slower as the kaolin clay fraction in the sandy substrate

  7. Biodegradation of 2,4,6-trichlorophenol and associated hydraulic conductivity reduction in sand-bed columns.

    PubMed

    Antizar-Ladislao, Blanca; Galil, Noah I

    2006-06-01

    The aim of this research was to investigate the long-term hydraulic conductivity changes in sand-bed columns exposed to 2,4,6-trichlorophenol (TCP). Continuous flow laboratory studies were conducted using sand-bed columns (15 cm i.d.; 200 cm length) at 20+/-1 degrees C during 365 d. The influence of (i) initial loads of 2,4,6-TCP (15, 30, 45 and 60 mg kg(-1) of 2,4,6-TCP), and (ii) recirculating water velocity (0.09, 0.56 and 1.18 cm min(-1)) on the biodegradation of 2,4,6-TCP and hydraulic conductivity changes in the sand-bed columns were investigated. The experimental results indicated that biodegradation of 2,4,6-TCP followed pseudo-first-order kinetics in the range of k(1)=0.01-1.64 d(-1), and it was influenced by initial load (p<0.01) and recirculating water velocity (p<0.01). Indigenous microbial biomass growth and changes resulted in a spatial (180 cm) and temporal (365 d) reduction of hydraulic conductivity in the sand-bed columns by up to two orders of magnitude during biodegradation of 2,4,6-TCP. The fastest hydraulic conductivity reductions were observed in the sand-bed column operated at the highest recirculating water velocity and highest cumulative load of 2,4,6-TCP following 365 d of continuous treatment (p<0.05).

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

    SciTech Connect

    Nelson, C.H.; Lee, H.L. ); Twichell, D.C.; Schwab, W.C. ); Kenyon, N.H. )

    1992-08-01

    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.

  9. Does streambed heterogeneity matter for hyporheic residence time distribution in sand-bedded streams?

    NASA Astrophysics Data System (ADS)

    Tonina, Daniele; de Barros, Felipe P. J.; Marzadri, Alessandra; Bellin, Alberto

    2016-10-01

    Stream water residence times within streambed sediments are key values to quantify hyporheic processes including sediment thermal regime, solute transient storage, dilution rates and biogeochemical transformations, such as those controlling degassing nitrous oxide. Heterogeneity of the streambed sediment hydraulic properties has been shown to be potentially an important factor to characterize hyporheic processes. Here, we quantify the importance of streambed heterogeneity on residence times of dune-like bedform induced hyporheic fluxes at the bedform and reach scales. We show that heterogeneity has a net effect of compression of the hyporheic zone (HZ) toward the streambed, changing HZ volume from the homogenous case and thus inducing remarkable differences in the flow field with respect to the homogeneous case. We unravel the physical conditions for which the commonly used homogenous field assumption is applicable for quantifying hyporheic processes thus explaining why predictive measures based on a characteristic residence time, like the Damköhler number, are robust in heterogeneous sand bedded streams.

  10. Thermal origin of continental red beds in SE China: An experiment study

    NASA Astrophysics Data System (ADS)

    Jiang, Lianting; Chen, Guoneng; Grapes, Rodney; Peng, Zhuolun

    2015-04-01

    The origin of continental red beds in SE China is the result of high diagenetic temperatures, rather than an arid climate during their deposition. Here we present results from an experimental study where black mud was heated to demonstrate the formation of red beds. Diffuse reflectance spectroscopy (DRS) of heated samples enables determination of the relative proportion of goethite and hematite. Iron in black mud is predominantly in the form of goethite that has an initial dehydration temperature of ca.150 °C. Increasing temperature or prolonged heating time is accompanied by decreasing goethite and organic content, increasing hematite and red colouration. Heat provided to subsiding red bed basins is supplied by cooling of an intracrustal granitic magma layer. The thermal model can explain vertical colour, temperature, redox and mineral zonation in red bed sequences, from red (hematite-bearing), through green-yellow (Cu, Zn, V sulphide mineralization) to grey-black (hydrocarbon, halite-bearing) sediments. The model can also be used to help prospect for hydrocarbon and halite deposits in the SE China red bed basins.

  11. IDENTIFICATION OF APPROPRIATE QUALIFICATION TESTING AND END-OF-LIFE WASTE STORAGE CONSIDERATIONS FOR DEEP BED SAND FILTERS

    SciTech Connect

    Matthews, K.

    2010-06-02

    Deep bed sand (DBS) filters have filtered radioactive particulates at two United States Department of Energy (DOE) sites since 1948. Some early DBS filters experienced issues with chemical attack on support tiles, requiring significant repairs. Designs of DBS filters constructed since 1970 paid greater attention to chemical compatibility, resulting in decades of reliable performance since 1975.

  12. Progress report number 2: investigations of some sedimentation characteristics of sand-bed streams

    USGS Publications Warehouse

    Hubbell, D.W.

    1960-01-01

    Hydraulic and sediment characteristics at six river sections upstream and downstream from the confluence of the Middle Loup and Dismal Rivers were measured and studied to determine some of the interrelationships between variables and the differences that exist between common variables when two flows unite. The two streams, which flow through the Sandhills region of Nebraska, have about the same water discharge, sediment concentration, and particle-size distribution of suspended sediment and bed material. Sediment discharges and flow resistances varied widely, although water discharges remained almost constant. The factor affecting the variations was water temperature, which ranged from 32° to 80° F. The bed form, which also varied with the water temperature, seemed to have a dominating influence on the sediment discharge, flow resistance, and possibly the vertical distribution of velocity and suspended sediment. Multiple regression with parameters derived from dimensional analysis yielded an expression for predicting the flow resistance and the widths and depths of individual channel sections. Contrary to those near many other confluences, slopes were steeper and channels were wider downstream from the junction of the two rivers than they were upstream. An investigation of specific sediment-transport phenomena and field procedures was made during 1956 and 1957 in cooperation with the U.S. Bureau of Reclamation. The purposes of this investigation were to provide information on the regime of rivers and to improve the procedures related to the collection of sediment data. The basic data and results of the studies made in 1956 were presented in progress report number 1, "Investigations of Some Sedimentation Characteristics of a Sand-Bed Stream." Some of the basic data and results of the studies made in 1957 are given in this report.

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

    SciTech Connect

    Burden, D.G.

    1988-01-01

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

  14. Continuous adsorption of Pb(II) and methylene blue by engineered graphite oxide coated sand in fixed-bed column

    NASA Astrophysics Data System (ADS)

    Gong, Ji-Lai; Zhang, Yong-Liang; Jiang, Yan; Zeng, Guang-Ming; Cui, Zhi-Hui; Liu, Ke; Deng, Can-Hui; Niu, Qiu-Ya; Deng, Jiu-Hua; Huan, Shuang-Yan

    2015-03-01

    The mixture of several effluents, caused by the improper handling and management of effluents, generated multi-component wastewater containing both metals and dyes, leading to the complicated treatment process. In this study, a continuous adsorption of Pb(II) and methylene blue (MB) has been studied in single and binary solutions by using graphite oxide coated sand (GO-sand) as an adsorbent in a fixed-bed column. GO-sand was analyzed by X-ray photoelectron spectroscopy before and after analyte adsorption. Compared with sand filter, adsorption quantity and capacity for Pb(II) and MB by GO-sand filter were greatly increased. In Pb(II) and MB single solutions, the experimental parameters were investigated in detail including initial concentration, flow rate, bed depth and pH. Exhaustion time decreased with increasing initial concentration and flow rate, and increased with increasing bed depth and pH. In the Pb(II)-MB binary solution, exhaustion time significantly decreased for Pb(II) adsorption, but increased for MB adsorption. The reason was explained that the more favorable adsorption for MB onto the surface of GO-sand than that for Pb(II), which was derived from π-π interaction between MB and GO on sand surface in packed filter. The Yoon-Nelson model was applied at different concentration of Pb(II) and MB to predict the breakthrough curves. The experimental data were well fit with the model indicating that it was suitable for this column design.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy) This article has been retracted at the request of the Editors-in-Chief. This article also contains significant similarity with parts of text, written by the same author(s), that have appeared in Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, The influence of sand diameter and wind velocity on sand particle lift-off and incident angles in the windblown sand flux, Sedimentary Geology, Volume 290, 15 May 2013, Pages 149-156. Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, The influence of wind velocity and sand grain diameter on the falling velocities of sand particles, Powder Technology, Volume 241, June 2013, Pages 158-165. Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, Analysis of sand particles' lift-off and incident velocities in wind-blown sand flux, Acta Mechanica Sinica, April 2013, Volume 29, Issue 2, pp 158-165. Tian-Li Bo, Xiao-Jing Zheng, Shao-Zhen Duan, Yi-Rui Liang, Influence of sand grain diameter and wind velocity on lift-off velocities of sand particles, The European Physical Journal E, May 2013, 36:50. The "slicing" of research that would form one meaningful paper into several different papers represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

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

    NASA Astrophysics Data System (ADS)

    Gorrick, S.; Rodriguez, J. F.

    2011-12-01

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

  17. Degradation of anionic surfactants during drying of UASBR sludges on sand drying beds.

    PubMed

    Mungray, Arvind Kumar; Kumar, Pradeep

    2008-09-01

    Anionic surfactant (AS) concentrations in wet up-flow anaerobic sludge blanket reactor (UASBR) sludges from five sewage treatment plants (STPs) were found to range from 4480 to 9,233 mg kg(-1)dry wt. (average 7,347 mg kg(-1)dry wt.) over a period of 18 months. After drying on sand drying beds (SDBs), AS in dried-stabilized sludges averaged 1,452 mg kg(-1)dry wt., a reduction of around 80%. The kinetics of drying followed simple first-order reduction of moisture with value of drying constant (k(d))=0.051 d(-1). Reduction of AS also followed first-order kinetics. AS degradation rate constant (k(AS)) was found to be 0.034 d(-1) and half-life of AS as 20 days. The order of rates of removal observed was k(d)>k(AS)>k(COD)>k(OM) (drying >AS degradation>COD reduction>organic matter reduction). For the three applications of dried-stabilized sludges (soil, agricultural soil, grassland), values of risk quotient (RQ) were found to be <1, indicating no risk.

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

    PubMed

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

    2009-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

  20. High Resolution, Millennial-Scale Patterns of Bed Compensation on a Sand-Rich Submarine Lobe, Western Niger Delta Slope

    NASA Astrophysics Data System (ADS)

    Jobe, Z. R.

    2014-12-01

    Existing facies models of submarine lobes suggest a thick, sand-rich proximal and axial part and thin, muddy distal and lateral fringes. This model was developed from observations in many areas where turbidity flows encounter a decrease in slope and collapse, depositing sand proximally and mud distally. This facies model is commonly used to explain stacking patterns encountered in outcrops and wellbores as well as to build reservoir models of lobe deposits. A submarine lobe on the modern seafloor of the western Niger Delta slope imaged with three-dimensional seismic data and sampled with 28 piston cores suggests that the traditional lobe facies model is not applicable. Fed by a single channel, the roughly symmetrical (9 km x 8 km) sand body occurs on a low gradient 'step' on the slope. The feeder channel ends abruptly at the apex of the lobe as the gradient decreases, and the lobe is not channelized. Seismic amplitudes are high across the lobe, and piston cores validate that these amplitudes correspond to sand. There is no significant change in sand percentage across the lobe, either parallel to or across flow direction. Bed thickness and grain size data do not show a decreasing trend downdip or laterally from the feeder channel. Radiocarbon age dating demonstrates bed-scale compensation across the lobe, with progressively younger turbidite sand beds stepping from north to south during a 2,000 year time interval (15,000-13,000 years before present) before lobe abandonment at 12,000 years before present. This progressive compensation, however, does not result in any facies change or any channelization on the lobe. At the downdip edge of the lobe, steeper gradients led to the development of a knickpoint and associated channel that continues downslope. The even sand distribution, lack of channelization, and downdip knickpoint suggest that the depositing turbidity flows must have been much larger than the accommodation, leading to sand deposition across the entire lobe

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

    USGS Publications Warehouse

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

    2011-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Oliver, Grahame; Prave, Anthony

    2013-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  4. Effect of filter media thickness on the performance of sand drying beds used for faecal sludge management.

    PubMed

    Manga, M; Evans, B E; Camargo-Valero, M A; Horan, N J

    2016-12-01

    The effect of sand filter media thickness on the performance of faecal sludge (FS) drying beds was determined in terms of: dewatering time, contaminant load removal efficiency, solids generation rate, nutrient content and helminth eggs viability in the dried sludge. A mixture of ventilated improved pit latrine sludge and septage in the ratio 1:2 was dewatered using three pilot-scale sludge drying beds with sand media thicknesses of 150, 250 and 350 mm. Five dewatering cycles were conducted and monitored for each drying bed. Although the 150 mm filter had the shortest average dewatering time of 3.65 days followed by 250 mm and 350 mm filters with 3.83 and 4.02 days, respectively, there was no significant difference (p > 0.05) attributable to filter media thickness configurations. However, there was a significant difference for the percolate contaminant loads in the removal and recovery efficiency of suspended solids, total solids, total volatile solids, nitrogen species, total phosphorus, chemical oxygen demand, dissolved chemical oxygen demand and biochemical oxygen demand, with the highest removal efficiency for each parameter achieved by the 350 mm filter. There were also significant differences in the nutrient content (NPK) and helminth eggs viability of the solids generated by the tested filters. Filtering media configurations similar to 350 mm have the greatest potential for optimising nutrient recovery from FS.

  5. Vertebrate biochronology of late Triassic red beds in New Mexico

    SciTech Connect

    Hunt, A.P. )

    1989-09-01

    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.

  6. Cold test with a benchtop set-up for fluidized bed reactor using quartz sand to simulate gasification of coal cokes by concentrated solar radiation

    NASA Astrophysics Data System (ADS)

    Gokon, Nobuyuki; Tanabe, Tomoaki; Shimizu, Tadaaki; Kodama, Tatsuya

    2016-05-01

    The impacts of internal circulation of a mixture of coal-coke particles and quartz sand on the fluidization state in a fluidized bed reactor are investigated by a cold test with a benchtop set-up in order to design 10-30 kWth scale prototype windowed fluidized-bed reactor. Firstly, a basic relationship between pressure loss of inlet gas and gas velocity was experimentally examined using quartz sand with different particle sizes by a small-scale quartz tube with a distributor at ambient pressure and temperature. Based on the results, an appropriate particle range of quartz sand and layer height/layer diameter ratio (L/D ratio) was determined for a design of the fluidized bed reactor. Secondly, a windowed reactor mock-up was designed and fabricated for solar coke gasification using quartz sand as a bed material. The pressure loss between the inlet and outlet gases was examined, and descending cokes and sand particles on the sidewall of the reactor was observed in the reactor mock-up. The moving velocity and distance of descending particles/sands from the top to bottom of fluidized bed were measured by the visual observation of the colored tracer particles on outside wall of the reactor.

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

    SciTech Connect

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

    2014-09-25

    The aim of this research is to synthesize nanoparticles of black pigment of Magnetite (Fe{sub 3}O{sub 4}), red pigment of hematite (α-Fe{sub 2}O{sub 3}), and yellow pigment of ghoetite (α-FeOOH) from the iron sand. The black pigment of Fe{sub 3}O{sub 4} and the yellow pigment α-FeOOH nanoparticles were synthesized by coprecipitation method with variation of pH. Whereas, the red pigment Fe{sub 2}O{sub 3} was synthesized by sintering Fe{sub 3}O{sub 4} nanoparticles at temperature between 400 °C and 700 7°C for 1 hour. All the pigments has been characterized using X-ray diffraction and SEM. The XRD results shown that the particle size of the black pigmen Fe{sub 3}O{sub 4}, red pigment Fe{sub 3}O{sub 4} and yellow pigment α-FeOOH are around 12, 32, and 30 nm respectively. The particle size of Fe{sub 2}O{sub 3} nanoparticles increase by increasing sintering temperature from 32 nm at 400 °C to 39 nm at 700 °C. For yellow pigment of α-FeOOH, the particle size increase by increasing pH from 30,54 nm at pH 4 to 48,60 nm at pH 7. The SEM results shown that the morphologies of black, yellow and red pigments are aglomarated.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The factors controlling the complex interaction of a coarse stream bed with flow and sediment are difficult to measure. However, planning for reservoir flushing or dam removal requires knowledge of these interactions. In both cases, impounded sediments are introduced to channel beds that have had ...

  12. Examining the generality of Tau_0/TKE for gravel and cobble beds with sand fill

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Turbulence measurements over rough beds are used for a variety of purposes, including studies of habitat diversity for aquatic organisms, stream restoration efforts, and assessment of drag induced by vegetation. Turbulent Kinetic Energy (TKE) has been used to determine bed shear stress by use of a ...

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The Cretaceous oceanic red bed (CORB) is a newly opened window on global oceanic and climate changes during the Cretaceous greenhouse world. As a result of the International Geoscience Programmes 463, 494 and 555 (2002-2010), CORBs have been documented in many places by numerous publications. The principle goal of this paper is to summarize scientific advances on CORBs including chronostratigraphy, sedimentology, mineralogy, elemental and isotopic geochemistry, and their relationship to oceanic anoxic events (OAEs), palaeoclimate and palaeoceanography. We propose a new geochemical classification of the CORBs using CaO, Al2O3 and SiO2 values, which lithologically refer to marly, clayey, and cherty CORBs respectively. Detailed mineralogical studies indicate that hematite, goethite and Mn2 +-bearing calcite are the minerals imparting the red color of CORBs. Hematite clusters of several to tens of nanometers in the calcite structure are the main cause of the red coloring of limestones, and the Mn2 +-bearing calcite gives additional red color. Goethite was thought to form originally with hematite, and was subsequently transformed to hematite during late diagenesis. Chronostratigraphic data allow the distinction of two groups of CORBs by their durations. Short-term CORBs are generally less than 1 myr in duration, and seem to be on the scale of Milankovitch cycles. During the deposition of Cretaceous reddish intervals from ODP cores 1049 and 1050, low primary productivity and relatively high surface temperature resulted in low organic carbon flux into the sediments which reduced oxygen demand and produced oxidizing early diagenetic conditions. In such an oxic environment, iron oxides formed imparting the reddish color. The long-term CORBs' depositional events lasted longer than 4 myr, and may be a possible consequence of the OAEs. Enhanced amounts of organic carbon and pyrite burial during and after the OAEs would have resulted in a large and abrupt fall in atmospheric CO

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

    USGS Publications Warehouse

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

    2008-01-01

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

  15. The Relation of Variability in Sand Bed Topography to Sediment Transport

    NASA Astrophysics Data System (ADS)

    McElroy, B.; Mohrig, D.

    2006-05-01

    The estimation of bed material flux by comparing successive bathymetric surveys was developed under a deterministic light. However, an analogous stochastic treatment can be straightforwardly cast as an extension to the original bedload equation. Instead of an analysis that presumes a regular, geometrically defined bed topography, this accepts the natural noisiness of sandy systems and uses it to explicitly calculate sediment flux. Further, the sediment flux can be treated as the sum of 2 components, a translative flux and a deformative flux. The terminology for these two parts is explicitly related to their relative impacts on the bed. Because the translational part is exactly the same as the original, deterministic model, it estimates only the flux that advects the bed topography. In contrast, the deformational part encompasses all of the remaining bed material flux, the component that serves to change the shape or arrangement of the bed topography. Also, the deformative flux is constant of integration obtained a from manipulation of Exner's equation into average flux; this has been assumed null since the inception of the bedload equation. Analysis of data from the N. Loup River, Nebraska, show that the ratio of deformative to translative fluxes is constant over relevant timescales. The consequences of this are twofold. First, the amount of deformation can be directly calculated and the associated estimates of moved sediment volume are valid as the bed translates many characteristic lengths. In this case the Qtotal=1.8*Qtranslative. Second, it suggests that the fraction of deformation can be explicitly related to the characteristic length of beds. If true, it would greatly improve estimates of flux for all sandy systems and not just those for which extensive amounts of data have been collected.

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

    USGS Publications Warehouse

    Marton, E.; Elston, D.P.

    1987-01-01

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

  17. A new technique for measuring the bed surface texture during flow and application to a degradational sand-gravel laboratory experiment

    NASA Astrophysics Data System (ADS)

    Orrú, Clara; Blom, Astrid; Chavarrías, Victor; Ferrara, Velia; Stecca, Guglielmo

    2016-09-01

    We present a new image analysis technique for measuring the grain size distribution (texture) of the bed surface during flow in a laboratory experiment. A camera and a floating device are connected to a carriage used to take images of the bed surface over the entire flume length. The image analysis technique, which is based on color segmentation, provides detailed data on spatial and temporal changes of the areal fraction content of each grain size at the bed surface. The technique was applied in a laboratory experiment conducted to examine a degradational reach composed of a well sorted two-fraction mixture of sand and gravel. The initial bed consisted of an upstream reach that was characterized by an imposed stepwise fining pattern (the bimodal reach) and a downstream sand reach. A lack of sediment supply and partial transport conditions led to the formation of a static armor in the bimodal reach, which resulted in a more abrupt spatial transition in the bed surface mean grain size. The associated spatial transition in slope led to a backwater effect over the bimodal reach, a streamwise reduction in sand mobility, and so a static armor that was governed by a downstream fining pattern. Although a morphodynamic equilibrium state under steady flow is generally characterized by normal flow, here the partial transport regime prevented the bed from adjusting toward normal flow conditions and the morphodynamic steady state was governed by a backwater. We applied a numerical morphodynamic sand-gravel model to reproduce the laboratory experiment. The numerical model captured the hydrodynamic and morphodynamic adjustment and the static armor well, yet the armoring occurred too slowly. Although the final configuration of the experiment shows features of a gravel-sand transition (i.e., a sudden transition in slope and mean grain size), we are hesitant to claim similarities between our results and the physical mechanisms governing a gravel-sand transition in the field.

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

    SciTech Connect

    Musselman, J.L. )

    1991-06-01

    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.

  19. Turbulence structure and sand transport over gravel and cobble beds in laboratory flumes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 r...

  20. Reduction of phosphorus, nitrogen and microorganisms in pilot scale sand filter beds containing biotite, treating primary wastewater.

    PubMed

    Matikka, Ville; Heinonen-Tanski, Helvi

    2016-01-01

    In sparsely populated areas, sand filter beds play an important role in wastewater treatment. As the need to improve the removal of nutrients increases, reactive filter materials represent one potential way to improve the reliability of current systems. We tested a pilot-scale multi-layer biotite filter for its ability to remove phosphorus, nitrogen, organic matter and enteric microorganisms with the importance of each layer in a multi-layer biotite filter being examined. In the experimental setup, the filters were fed with a raw wastewater influent mimicking the usual daily rhythm of water consumption and the reduction effects of the variable loads were examined during the experiment time of 54 weeks. It was observed that the reduction efficiency of the phosphorus was good (87%) during normal and under loading sequences but the reduction achieved for nitrogen was poor (27%). During and after overloading sequences, the phosphorus reduction was poor (46.5%) whereas the nitrogen reduction improved (to 66.7%). The reduction of organic matter was good during all sequences. The reductions of enteric microorganisms were at a level of 2-3 log10 units already after a single sand layer. For Escherichia coli, reductions of more than 5 log10 units were found after the wastewater had passed through a multilayer biotite filter during all sequences. It is concluded that the inclusion of a biotite layer improves the reliability of the filter bed. However, the proper scaling of the unit is essential in order to guarantee that the filter remains in aerobic conditions.

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

    NASA Astrophysics Data System (ADS)

    Bilardello, D.; Kodama, K. P.

    2008-12-01

    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

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

    PubMed

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

    2008-12-15

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

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

    USGS Publications Warehouse

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

    1973-01-01

    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.

  4. Accurate reservoir evaluation from borehole imaging techniques and thin bed log analysis: Case studies in shaly sands and complex lithologies in Lower Eocene Sands, Block III, Lake Maracaibo, Venezuela

    SciTech Connect

    Coll, C.; Rondon, L.

    1996-08-01

    Computer-aided signal processing in combination with different types of quantitative log evaluation techniques is very useful for predicting reservoir quality in complex lithologies and will help to increase the confidence level to complete and produce a reservoir. The Lower Eocene Sands in Block III are one of the largest reservoirs in Block III and it has produced light oil since 1960. Analysis of Borehole Images shows the reservoir heterogeneity by the presence of massive sands with very few shale laminations and thinnly bedded sands with a lot of laminations. The effect of these shales is a low resistivity that has been interpreted in most of the cases as water bearing sands. A reduction of the porosity due to diagenetic processes has produced a high-resistivity behaviour. The presence of bed boundaries and shales is detected by the microconductivity curves of the Borehole Imaging Tools allowing the estimation of the percentage of shale on these sands. Interactive computer-aided analysis and various image processing techniques are used to aid in log interpretation for estimating formation properties. Integration between these results, core information and production data was used for evaluating producibility of the reservoirs and to predict reservoir quality. A new estimation of the net pay thickness using this new technique is presented with the consequent improvement on the expectation of additional recovery. This methodology was successfully applied in a case by case study showing consistency in the area.

  5. Network response to internal and external perturbations in large sand-bed braided rivers

    NASA Astrophysics Data System (ADS)

    Schuurman, F.; Kleinhans, M. G.; Middelkoop, H.

    2015-03-01

    The intrinsic instability of bars, bifurcations and branches in large braided rivers is a challenge to understand and predict. Even more, the reach-scale effect of human-induced perturbations on the braided channel network is still unresolved. In this study, we used a physics-based model to simulate the hydromorphodynamics in a large braided river and applied different types of perturbations. We analyzed the propagation of the perturbations through the braided channel network. The results showed that the perturbations initiate an instability that propagates in downstream direction by means of bifurcation instability. It alters and rotates the approaching flow of the bifurcations. The propagation celerity is in the same order of magnitude as the theoretical sand wave propagation rate. The adjustments of the bifurcations also change bar migration and reshape, with a feedback to the upstream bifurcation and alteration of the approaching flow to the downstream bifurcation. This way, the morphological effect of a perturbation amplifies in downstream direction. Thus, the interplay of bifurcation instability and asymmetrical reshaping of bars was found to be essential for propagation of the effects of a perturbation. The study also demonstrated that the large-scale bar statistics are hardly affected.

  6. 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

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

    1989-03-01

    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.

  7. Hydrology and bedload transport relationships for sand-bed streams in the Ngarradj Creek catchment, northern Australia

    NASA Astrophysics Data System (ADS)

    Erskine, W. D.; Saynor, M. J.

    2013-03-01

    SummaryRainfall, discharge and bedload were measured at three gauging stations (East Tributary, Upper Swift Creek and Swift Creek) in the Ngarradj Creek catchment at Jabiluka, Northern Territory, Australia. Hand-held, pressure difference, Helley-Smith bedload samplers were used to measure bedload fluxes for the 1998/1999, 1999/2000, 2000/2001 and 2001/2002 wet seasons. Rainfall is strongly seasonal over the Ngarradj Creek catchment, being concentrated in the wet season between November and April. Mean annual point rainfall between 1998 and 2007 for the water year, September to August, inclusive varied over the Ngarradj Creek catchment from 1731 ± 98 mm (SE) to 1754 ± 116 mm. Between 190 and 440 mm of rainfall are required before streamflow commences in December in most years. Streamflow persists until at least April. Mean annual runoff, as a percentage of mean annual rainfall, decreases slightly with increasing catchment area. Bedload ratings were calculated for four data sets. Significant bedload ratings were defined as those that were not only statistically significant (ρ ⩽ 0.05) but also explained at least 0.60 of the variance in bedload flux. For the three stations, twenty-three bedload ratings complied with the above criteria. Sixteen equations were accepted for East Tributary, four bedload ratings were accepted for Upper Swift Creek and three bedload ratings were accepted for Swift Creek. Significant bedload ratings were established between bedload flux and discharge, unit bedload flux and discharge, transport rate of unsuspended bedload by immersed weight per unit width and time and both unit and excess unit stream power, and finally, adjusted submersed bedload weight and both unit and excess unit stream power for raw and log10-transformed data. 'Censored data sets' were compiled for Upper Swift Creek and Swift Creek to include only bedload fluxes measured when there was no apparent scour or fill so that there were no changes in sand supply from the

  8. Effect of sand bed depth and media age on Escherichia coli and turbidity removal in biosand filters.

    PubMed

    Napotnik, Julie A; Baker, Derek; Jellison, Kristen L

    2017-02-17

    The main objective of this study was to build several full-scale biosand filters (BSFs) and assess the long-term (9 month) efficacy for particulate and Escherichia coli removal under simulated real-world usage. Four replicates of three different filter designs were built: the traditional concrete BSF, and two scaled-down versions that use a 5-gal or 2-gal bucket, respectively, as the casing material. The smaller sand bed depths in the bucket-sized filters did not impact filter performance with respect to (i) turbidity and E. coli removal or (ii) effluent levels of turbidity and E. coli. All filters produced effluents with a mean turbidity of <0.6 NTU. In addition, 78%, 74%, and 72% of effluent samples for the concrete, 5-gal, and 2-gal filters, respectively, had E. coli concentrations <1 CFU/100 mL. The bucket-sized filters were found to be a potential alternative to the concrete BSFs for the removal of E. coli and turbidity from drinking water. Since smaller BSFs must be filled more frequently than larger BSFs to produce comparable water volumes, the effect of shorter pause periods on BSF performance should be investigated.

  9. A computational investigation of the interstitial flow induced by a variably thick blanket of very fine sand covering a coarse sand bed

    NASA Astrophysics Data System (ADS)

    Bartzke, Gerhard; Huhn, Katrin; Bryan, Karin R.

    2017-03-01

    Blanketed sediment beds can have different bed mobility characteristics relative to those of beds composed of uniform grain-size distribution. Most of the processes that affect bed mobility act in the direct vicinity of the bed or even within the bed itself. To simulate the general conditions of analogue experiments, a high-resolution three-dimensional numerical `flume tank' model was developed using a coupled finite difference method flow model and a discrete element method particle model. The method was applied to investigate the physical processes within blanketed sediment beds under the influence of varying flow velocities. Four suites of simulations, in which a matrix of uniform large grains (600 μm) was blanketed by variably thick layers of small particles (80 μm; blanket layer thickness approx. 80, 350, 500 and 700 μm), were carried out. All beds were subjected to five predefined flow velocities (U 1-5=10-30 cm/s). The fluid profiles, relative particle distances and porosity changes within the bed were determined for each configuration. The data show that, as the thickness of the blanket layer increases, increasingly more small particles accumulate in the indentations between the larger particles closest to the surface. This results in decreased porosity and reduced flow into the bed. In addition, with increasing blanket layer thickness, an increasingly larger number of smaller particles are forced into the pore spaces between the larger particles, causing further reduction in porosity. This ultimately causes the interstitial flow, which would normally allow entrainment of particles in the deeper parts of the bed, to decrease to such an extent that the bed is stabilized.

  10. Rock magnetic evidence for inclination shallowing in the early Carboniferous Deer Lake Group red beds of western Newfoundland

    NASA Astrophysics Data System (ADS)

    Bilardello, Dario; Kodama, Kenneth P.

    2010-04-01

    A paleomagnetic and rock magnetic study of the Carboniferous Deer Lake Group red beds of Newfoundland was performed to detect and correct for inclination shallowing. Results indicate a primary remanence carried by magnetite, with a mean direction of D = 179.7°, I = 33.7°, α95 = 7.2° which corresponds to a paleopole position of 22.2°N, 122.3°E, A95 = 7.6°. Correcting the inclination using anisotropy of anhysteretic remanence and the measured individual particle anisotropy gives a corrected direction of D = 178.8°, I = 50.9°, α95 = 6.3° corresponding to a paleopole position at 8.4°N, 122.7°E, A95 = 7.2°. This correction is larger than that of other red beds from the Maritime Provinces of Canada, but is consistent with paleoenvironmental reconstructions, placing North America in a more arid climate zone. Our inclination-corrected results have important implications for this portion of North America's apparent polar wander path and suggest a correction is needed for other red bed-derived APWPs. We have determined the range of flattening factors f, defined as the proportionality constant between the tangents of the measured (Im) and field (Io) inclinations, tan(Im) = ftan(I0), from this study and previous inclination correction studies to estimate inclination corrections. Using the range of haematite f factors observed in this study to correct the Neogene red bed inclinations from the Vallès-Penedès Basin (NE Spain) yields inclinations consistent with the known geomagnetic field inclination in the Neogene, thus indicating that the range of f factors reported here may be used to estimate the magnitude of inclination shallowing in red beds.

  11. Spatial Scaling of Environmental Variables Improves Species-Habitat Models of Fishes in a Small, Sand-Bed Lowland River

    PubMed Central

    Radinger, Johannes; Wolter, Christian; Kail, Jochem

    2015-01-01

    Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological and in-stream habitat variables and their spatial scales of influence is poorly understood. Applying boosted regression trees, we developed species-habitat models for 13 fish species in a sand-bed lowland river based on river morphological and in-stream habitat data. First, we calculated mean values for the predictor variables in five distance classes (from the sampling site up to 4000 m up- and downstream) to identify the spatial scale that best predicts the presence of fish species. Second, we compared the suitability of measured variables and assessment scores related to natural reference conditions. Third, we identified variables which best explained the presence of fish species. The mean model quality (AUC = 0.78, area under the receiver operating characteristic curve) significantly increased when information on the habitat conditions up- and downstream of a sampling site (maximum AUC at 2500 m distance class, +0.049) and topological variables (e.g., stream order) were included (AUC = +0.014). Both measured and assessed variables were similarly well suited to predict species’ presence. Stream order variables and measured cross section features (e.g., width, depth, velocity) were best-suited predictors. In addition, measured channel-bed characteristics (e.g., substrate types) and assessed longitudinal channel features (e.g., naturalness of river planform) were also good predictors. These findings demonstrate (i) the applicability of high resolution river morphological and instream-habitat data (measured and assessed variables) to predict fish presence, (ii) the

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  13. Spatial Scaling of Environmental Variables Improves Species-Habitat Models of Fishes in a Small, Sand-Bed Lowland River.

    PubMed

    Radinger, Johannes; Wolter, Christian; Kail, Jochem

    2015-01-01

    Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological and in-stream habitat variables and their spatial scales of influence is poorly understood. Applying boosted regression trees, we developed species-habitat models for 13 fish species in a sand-bed lowland river based on river morphological and in-stream habitat data. First, we calculated mean values for the predictor variables in five distance classes (from the sampling site up to 4000 m up- and downstream) to identify the spatial scale that best predicts the presence of fish species. Second, we compared the suitability of measured variables and assessment scores related to natural reference conditions. Third, we identified variables which best explained the presence of fish species. The mean model quality (AUC = 0.78, area under the receiver operating characteristic curve) significantly increased when information on the habitat conditions up- and downstream of a sampling site (maximum AUC at 2500 m distance class, +0.049) and topological variables (e.g., stream order) were included (AUC = +0.014). Both measured and assessed variables were similarly well suited to predict species' presence. Stream order variables and measured cross section features (e.g., width, depth, velocity) were best-suited predictors. In addition, measured channel-bed characteristics (e.g., substrate types) and assessed longitudinal channel features (e.g., naturalness of river planform) were also good predictors. These findings demonstrate (i) the applicability of high resolution river morphological and instream-habitat data (measured and assessed variables) to predict fish presence, (ii) the

  14. Transcriptome analysis of bagging-treated red Chinese sand pear peels reveals light-responsive pathway functions in anthocyanin accumulation.

    PubMed

    Bai, Songling; Sun, Yongwang; Qian, Minjie; Yang, Fengxia; Ni, Junbei; Tao, Ruiyan; Li, Lin; Shu, Qun; Zhang, Dong; Teng, Yuanwen

    2017-12-01

    Bagging is an efficient method to improve fruit colour development. This work reported a transcriptome analysis using bagging-treated red Chinese sand pear peels. In total, 8,870 differentially expressed genes were further analysed by a weighted gene co-expression network analysis and early-, middle- and late light-responsive genes were identified. An annotation analysis revealed several pathways involved in the different responsive stages. The presence of LONG HYPOCOTLY 5, CRY-DASH and a CONSTANS-like transcription factors among the early light-responsive genes indicated the pivotal role of light, especially blue light, in the biological changes that occurred after bag removal. Other light-responsive transcription factors were also identified from the three light-responsive stages. In addition, the light-responsive pattern of anthocyanin biosynthetic genes differed among the biosynthetic steps. Although yeast-one hybrid assay showed that most of the structural genes were regulated by PpMYB10, their different temporal expressive pattern suggested that besides PpMYB10, other light-responsive transcriptional factors were also involved in the regulation of anthocyanin biosynthesis. In summary, our transcriptome analysis provides knowledge of the transcriptional regulatory network operating during light responses, which results in anthocyanin accumulation and other significant physiological changes in red Chinese sand pear peels after bag removal.

  15. Red River of the North Reconnaissance Report: Sand Hill River Subbasin.

    DTIC Science & Technology

    1980-12-01

    River Subbasin. . . . 28 7 Groundwater Quality Data From Cmunities in the Sand Hill River Subbasin. . . . . . .................. .. 30 8 Comparison of...be significant. Groundwater quality problems are related to excessive concentrations of iron, manganese, sulfates, and total dissolved solids (Upper...is little natural storage potential for surface water supplies in the subbasin. Groundwater contributions to the river are minimal in the western

  16. The Transfiguration continental red-bed Cu-Pb-Zn-Ag deposit, Quebec Appalachians, Canada

    NASA Astrophysics Data System (ADS)

    Cabral, Alexandre Raphael; Beaudoin, Georges; Taylor, Bruce E.

    2009-04-01

    The Transfiguration Cu-Pb-Zn-Ag deposit, enclosed within reduced grey sandstone, is associated with continental red beds of the Lower Silurian Robitaille Formation in the Quebec Appalachians, Canada. The Robitaille Formation rests unconformably on foliated Cambro-Ordovician rocks. The unconformity is locally cut by barite veins. The basal unit of the Robitaille Formation comprises green wacke and pebble conglomerate, which locally contain calcite nodules. The latter have microstructures characteristic of alpha-type calcretes, such as “floating” fabrics, calcite-filled fractures (crystallaria) and circumgranular cracks. Massive, grey sandstone overlies the basal green wacke and pebble conglomerate unit, which is overlain, in turn, by red, fine-grained sandstone. Mineralisation occurred underneath the red sandstone unit, chiefly in the grey sandstone unit, as disseminated and veinlet sulphides. Chalcopyrite, the most abundant Cu sulphide, replaced early pyrite. Calcrete, disseminated carbonate and vein carbonate have stable isotope ratios varying from -7.5‰ to -1.1‰ δ13C and from 14.7‰ to 21.3‰ δ18O. The negative δ13C values indicate the oxidation of organic matter in a continental environment. Sulphur isotope ratios for pyrite, chalcopyrite and galena vary from -19‰ to 25‰ δ34S, as measured on mineral concentrates by a conventional SO2 technique. Laser-assisted microanalyses (by fluorination) of S isotopes in pyrite show an analogous range in δ34S values, from -21‰ to 25‰. Negative and positive δ34S values are compatible with bacterial sulphate reduction (BSR) in systems open and closed with respect to sulphate. We interpret similarly high δ34S values for sulphide concentrates (25.1‰) and for vein barite (26.2‰) to result from rapid and complete thermochemical reduction of pore-water sulphate. Two early to late diagenetic stages of mineralisation best explain the origin of the Transfiguration deposit. The first stage was characterised

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    The `Cyborg Astrobiologist' has undergone a second geological field trial, at a site in northern Guadalajara, Spain, near Riba de Santiuste. The site at Riba de Santiuste is dominated by layered deposits of red sandstones. The Cyborg Astrobiologist is a wearable computer and video camera system that has demonstrated a capability to find uncommon interest points in geological imagery in real time in the field. In this second field trial, the computer vision system of the Cyborg Astrobiologist was tested at seven different tripod positions, on three different geological structures. The first geological structure was an outcrop of nearly homogeneous sandstone, which exhibits oxidized-iron impurities in red areas and an absence of these iron impurities in white areas. The white areas in these `red beds' have turned white because the iron has been removed. The iron removal from the sandstone can proceed once the iron has been chemically reduced, perhaps by a biological agent. In one instance the computer vision system found several (iron-free) white spots to be uncommon and therefore interesting, as well as several small and dark nodules. The second geological structure was another outcrop some 600 m to the east, with white, textured mineral deposits on the surface of the sandstone, at the bottom of the outcrop. The computer vision system found these white, textured mineral deposits to be interesting. We acquired samples of the mineral deposits for geochemical analysis in the laboratory. This laboratory analysis of the crust identifies a double layer, consisting of an internal millimetre-size layering of calcite and an external centimetre-size efflorescence of gypsum. The third geological structure was a 50 cm thick palaeosol layer, with fossilized root structures of some plants. The computer vision system also found certain areas of these root structures to be interesting. A quasi-blind comparison of the Cyborg Astrobiologist's interest points for these images with the

  18. New paleomagnetic data from carboniferous volcanics and red beds from central New Brunswick

    NASA Astrophysics Data System (ADS)

    Seguin, Maurice K.; Singh, A.; Fyffe, L.

    1985-02-01

    It has long been argued, on the basis of paleomagnetic data derived from Devonian, Carboniferous and Permian lithological units from eastern North America that a sinistral megashear of Carboniferous age parallels and lies within the faults delimiting the Appalachian-Caledonian chains. Recent paleomagnetic studies in the northern Appalachians have cast doubt on the models of a Carboniferous offset. The geologic evidence suggests that only a small amount of dextral (and not sinistral) strike slip has occurred on faults which are parallel with pre-Acadian paleogeographic realms. The purpose of this paleomagnetic study is to test the validity of the proposed left-lateral motion at one of the sites of its presumed passage in central New Brunswick. Six sites (80 oriented specimens) in Carboniferous red beds and volcanics were collected on both sides of the Fredericton Fault and other parallel faults. After AF and thermal cleaning, the mean direction of magnetization is 158° + 38° the fold test is indecisive. The corresponding paleopole is 135°E, 21°N and the paleolatitude 20°S. The paleopole positions and paleolatitudes are not significantly different on either side of the Fredericton fault and no left-lateral motion was detected by paleomagnetic means. As no such motion was detected in south-central New Brunswick and Newfoundland, it is possible but unlikely that it took place in northern New Brunswick and in the western Gaspé Peninsula. This contribution is useful in discussing possible motions of Acadia.

  19. Advancement of an Infra-Red Technique for Whole-Field Concentration Measurements in Fluidized Beds

    PubMed Central

    Medrano, Jose A.; de Nooijer, Niek C. A.; Gallucci, Fausto; van Sint Annaland, Martin

    2016-01-01

    For a better understanding and description of the mass transport phenomena in dense multiphase gas-solids systems such as fluidized bed reactors, detailed and quantitative experimental data on the concentration profiles is required, which demands advanced non-invasive concentration monitoring techniques with a high spatial and temporal resolution. A novel technique based on the selective detection of a gas component in a gas mixture using infra-red properties has been further developed. The first stage development was carried out using a very small sapphire reactor and CO2 as tracer gas. Although the measuring principle was demonstrated, the real application was hindered by the small reactor dimensions related to the high costs and difficult handling of large sapphire plates. In this study, a new system has been developed, that allows working at much larger scales and yet with higher resolution. In the new system, propane is used as tracer gas and quartz as reactor material. In this study, a thorough optimization and calibration of the technique is presented which is subsequently applied for whole-field measurements with high temporal resolution. The developed technique allows the use of a relatively inexpensive configuration for the measurement of detailed concentration fields and can be applied to a large variety of important chemical engineering topics. PMID:26927127

  20. The Role of Authigenic (pigment) Hematite in Controlling the Remanence, Rock Magnetic, and Magnetic Fabric Properties of Red Beds--If You Have Seen One Red Bed, You Certainly Have Not Seen Them All!

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.

    2014-12-01

    Discussion continues on the relative role of authigenic (pigment) fine-grained hematite, relative to detrital, considerably coarser specular hematite (specularite) as a carrier of geologically meaningful remanence, as a determinant of rock magnetic properties, and as a contributor to magnetic fabrics in red beds. For one, many workers commonly assume that the laboratory unblocking temperature spectra (Tlub) of a red bed dominated by authigenic pigment does not reach the maximum Tlub as approximated by the Neel temperature (~948 K) because of the ultra fine grain size of the pigment. This issue was discussed as recently as the IRM Santa Fe meeting in late June, 2014. Many laboratories routinely utilize chemical demagnetization in concert with progressive thermal demagnetization to attempt to assess the relative role of pigment vs. detrital hematite. However, the utility of chemical demagnetization has been long challenged. In studying the anisotropy of magnetic susceptibility and remanence in red beds, recent work has considered separating the contributions of both types of hematite to the fabric signal. Three different red bed "types" (siltstones of the Triassic Chugwater Group, Gros Ventre Range, Wyoming; mudrocks of lowermost Triassic Quartermaster Formation, west Texas; and siltstones to medium sandstones of Upper Cretaceous age, northwest Vietnam) are used to evaluate the effects of varying contributions by pigment hematite to remanence, rock magnetic, and magnetic fabric properties. All rocks are well-characterized petrographically, so that the modal abundance of detrital oxides is known. The Chugwater siltstones are notable because of a relatively low Tlub spectra (below about 620o C), with no evidence of a low coercivity cubic phase. Rock magnetic and magnetic fabric properties are monitored as a function of progressive chemical demagnetization to further elucidate the role of hematite pigment in rocks that have contributed much to the paleomagnetic record

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

    NASA Astrophysics Data System (ADS)

    Guidetti, P.

    2000-04-01

    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 observed over the Posidonia seagrass and, in turn, the rocky-algal reef and unvegetated sand habitats. Planktivorous fish species ( Spicara maena, Spicara smaris and Chromis chromis) showing patchy distributions were dominant in terms of abundance at both localities. The two former species did not show any particular habitat preference, while C. chromis was common over both the Posidonia and rocky-algal habitats and was only occasionally recorded over sand. Symphodus ocellatus , Diplodus annularis and Spondyliosoma cantharus were the most common species in the P. oceanica seagrass beds. Symphodus roissali, Symphodus tinca and Diplodus sargus were mainly associated with the rocky-algal reef habitats, while other species, such as Gymnammodytes cicerellus, Lithognathus mormyrus , Gobius geniporus, Mullus barbatus and Uranoscopus scaber, were censused over the unvegetated sand habitats. A cluster analysis performed on the entire fish density data set showed distinct groupings for seagrass, rocky-algal and bare sand fish assemblages, regardless of season and sampling site. Fish assemblages in the more structured (seagrass and rocky-algal reef) habitats were relatively similar to each other but quite different from those of the unstructured bare sands. With regard to small-sized specimens (juvenile stages including recruits), those of S. ocellatus, Symphodus mediterraneus, Serranus cabrilla, D. annularis, S. cantharus and Sarpa salpa were mainly censused over P. oceanica beds, while juveniles of C. chromis inhabited predominantly

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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 Rλ 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

  3. Combined use of thermal methods and seepage meters to efficiently locate, quantify, and monitor focused groundwater discharge to a sand-bed stream

    NASA Astrophysics Data System (ADS)

    Rosenberry, Donald O.; Briggs, Martin A.; Delin, Geoffrey; Hare, Danielle K.

    2016-06-01

    Quantifying flow of groundwater through streambeds often is difficult due to the complexity of aquifer-scale heterogeneity combined with local-scale hyporheic exchange. We used fiber-optic distributed temperature sensing (FO-DTS), seepage meters, and vertical temperature profiling to locate, quantify, and monitor areas of focused groundwater discharge in a geomorphically simple sand-bed stream. This combined approach allowed us to rapidly focus efforts at locations where prodigious amounts of groundwater discharged to the Quashnet River on Cape Cod, Massachusetts, northeastern USA. FO-DTS detected numerous anomalously cold reaches one to several m long that persisted over two summers. Seepage meters positioned upstream, within, and downstream of 7 anomalously cold reaches indicated that rapid groundwater discharge occurred precisely where the bed was cold; median upward seepage was nearly 5 times faster than seepage measured in streambed areas not identified as cold. Vertical temperature profilers deployed next to 8 seepage meters provided diurnal-signal-based seepage estimates that compared remarkably well with seepage-meter values. Regression slope and R2 values both were near 1 for seepage ranging from 0.05 to 3.0 m d-1. Temperature-based seepage model accuracy was improved with thermal diffusivity determined locally from diurnal signals. Similar calculations provided values for streambed sediment scour and deposition at subdaily resolution. Seepage was strongly heterogeneous even along a sand-bed river that flows over a relatively uniform sand and fine-gravel aquifer. FO-DTS was an efficient method for detecting areas of rapid groundwater discharge, even in a strongly gaining river, that can then be quantified over time with inexpensive streambed thermal methods.

  4. Leaded red brass, sand and centrifugal castings, 85Cu 5.0Sn 5.0Pb 5.0Zn as cast. (SAE standard)

    SciTech Connect

    1993-04-01

    This specification covers a leaded red brass alloy in the form of sand and centrifugal castings. It is used for parts, such as fittings in fluid conducting lines, where soundness of castings is of prime importance, but usage is not limited to such applications. Alloy: 836 UNS Number: C8360.

  5. Continental Red Beds: How, Why, and When Can they Be Remagnetized, and What Would Don Elston Think?

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.

    2006-12-01

    For logical reasons, continental red beds have served as the focus for thousands of paleomagnetic investigations; this author is becoming more and more convinced that the most accurate statements to make about how red beds are magnetized are: (1)no two red bed sequences are exactly the same and (2)understanding just how red beds are remagnetized (a nagging question pondered by several workers) may help us in more fully understanding aspects of how they acquire a geologically meaningful magnetization in the first place! Red beds of the Uinta Mountain Supergroup (UMS) serve as an excellent natural laboratory for studying magnetization acquisition and remagnetization processes. These rocks are exposed in the core of the Uinta Mountains, which formed during Laramide style shortening along the northern margin of the Colorado Plateau. In the eastern and central part of the range, strata are dominated by 3+ km of hematite-cemented medium to fine-grained sandstones, with relatively minor hematitic shales and conglomerates. Correlation of the upper part of the UMS section with the Chuar and Little Dal groups, and hence a mid-Neoproterozoic age for the strata, is based on the presence of the fossil Chuaria. At several localities in UMG strata, a dual polarity ChRM of about east-west declination and shallow inclination inferred to be primary) is smoothly and progressively unblocked between about 590 and 685°C, with no hint of changes in magnetic mineralogy and/or viscous behavior during unblocking. This magnetization provides a paleomagnetic pole of 0.8°N and 161.3°E (Weil,Geissman,and Ashby,2006, PC Res.) Several localities, in particular in the eastern part of the uplift, however, have been completely remagnetized and contain a pervasive and exceedingly well- defined, well-grouped magnetization that is consistent with a young, certainly post mid-Cretaceous, age of remagnetization. In chemical demagnetization, this secondary magnetization is completely removed over short

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  7. Mars ecopoiesis test bed: on earth and on the red planet

    NASA Astrophysics Data System (ADS)

    Todd, Paul; Kurk, Michael Andy; Boland, Eugene; Thomas, David; Scherzer, Christopher

    2016-07-01

    The concept of autotrophic organisms serving as planetary pioneers as a precursor to terraforming has been under consideration for several decades, and the term Ecopoiesis was introduced by the ecopoiets C. Sagan, M. Avener, R. Haynes and C. McKay to call attention to this possibility. There is a continuing need for experimental evidence to support this concept, one of them being the need to evaluate the survivability of terrestrial autotrophic microbes in a planetary environment. For this and other purposes a planetary simulation facility was constructed and operated at Techshot, Inc. in Indiana, USA. This facility has an accumulated record of more than one year's worth of experimentation under simulated Mars conditions. In a recent study this facility was operated for five weeks in a mode that simulated 35 sols on and just below the surface of Mars at low latitude. The diurnal lighting period was 12 hours:12 hours using xenon arc light filtered to simulate the solar intensity and spectrum on the Martian surface. A daily temperature profile followed that recorded at low latitudes with night-time minima at -80 C and noontime maxima at +26 C. Atmosphere was CO _{2} at <11 mbar. Moisture was monitored to confirm that no water could exist in the liquid phase. Test organisms included the cyanobacteria Anabena, sp., Chroococcidiopsis CCMEE171 and Plectonema boryanum and Eukaryota: Chlorella ellipsoidia maintained in the simulator under the above-described conditions. The exposed specimens were tested for intracellular esterase activity, chlorophyll content and reproductive survival. All tests yielded low-level positive survival results for these organisms. No definitive data relating to function and/or growth during exposure were sought. In parallel to these terrestrial studies a planned design study was undertaken for a proposed test bed to be operated on the surface of Mars. Design requirements include compact assembly for transport and installation on the planetary

  8. Paleomagnetism of the Oligocene Kangtuo Formation red beds (Central Tibet): Inclination shallowing and tectonic implications

    NASA Astrophysics Data System (ADS)

    Ding, Jikai; Zhang, Shihong; Chen, Weiwei; Zhang, Junhong; Yang, Tianshui; Jiang, Gaolei; Zhang, Kexin; Li, Haiyan; Wu, Huaichun

    2015-05-01

    A paleomagnetic study on the red beds of the Oligocene Kangtuo Formation (Fm) was carried out in the Gerze Basin of the Lhasa terrane. A total of 700 samples were collected from 37 sites. Stepwise thermal demagnetization revealed that the main magnetic carrier is hematite. The natural remnant magnetization (NRM) consists of two components. A low-temperature component (LTC) is identified below 300 °C and is interpreted to be a recent viscous overprint, whereas a high temperature component (HTC) unblocks at ∼665-690 °C and is interpreted to be the primary magnetization. The HTC distributions show a clear east-west elongated distribution, which is considered as reflecting inclination flattening of deposited magnetic remanence carriers. After inclination calibration using the E/I method, the HTC could pass both a reversal test and a fold test at 95% confidence level, showing the mean direction at Ds = 340.3°, Is = 44.2°, with k = 63.0, and α95 = 3.1°, corresponding to a paleopole at 71.7°N, 339.3°E (A95 = 3.1°), and the paleolatitude of the sampling site at 25.9 ± 3.1°N. The paleolatitude is consistent with that expected from the coeval pole of the Qiangtang terrane obtained from volcanic rocks, suggesting that there has been no paleomagnetically-discernable latitudinal motion between the Qiantang and Lhasa terranes since ∼30 Ma. Comparing our new data with the apparent polar wander paths (APWPs) of East Asian blocks (Cogné et al., 2013), Europe, and India (Besse and Courtillot, 2002), we have reached the following conclusions. (1) There is no significant paleolatitudinal difference observed between the Lhasa terrane and other central and northern Asian terranes at ∼30 Ma. (2) The observed paleolatitude of the Kangtuo Fm is 8.0 ± 4.9° lower than the expected paleolatitude deduced from the data of stable Europe, highlighting the 'Asian inclination anomaly' phenomenon, but is 4.6 ± 5.1° higher than that deduced from the data of the India Plate

  9. Diagenetic crystallization and oxidation of siderite in red bed (Buntsandstein) sediments from the Central Iberian Chain, Spain

    NASA Astrophysics Data System (ADS)

    Stel, Harry

    2009-01-01

    Compactional deformation facilitated replacement of dolomite and calcite by siderite and its subsequent oxidation in carbonate cemented red beds of the Triassic Buntsandstein in the Iberian Chain. Locally, the sedimentary clasts were cemented by carbonate that was derived from dissolution of locally exposed dolomite in the basement. Microstructures indicate that during sedimentation of the rocks, oxidizing conditions prevailed in the sediments and the basement was reddened by impregnation of hematite. Reducing conditions prevailed during deformation of the sediments. Ferric iron was reduced to Fe 2+, that reacted with deformed dolomite and calcite cement to produce fine grained siderite. At a later stage, siderite crystallites were (partly) oxidized to form a secondary phase of brown ferric oxide (goethite). Locally, goethite transformed to fine grained hematite that caused secondary reddening of the sediments. The reactions are associated with a combined volume loss of the solid phases of c. 50% per reaction mol; this was accommodated by the formation of pores. Oxidation of siderite was associated with release of CO 2; localized dissolution took place of feldspar and concurrently growth of kaolinite occurred by acidifying condition during release of CO 2. The relation of redox reactions and deformation is comparable to those in red bed conglomerates in the region. Reductive dissolution occurred at sites of stress concentration, particularly at contact points of pebbles. Late stage precipitation of ferric oxides and pyrolusite took place at oxidizing conditions in association with uplift.

  10. Tectonic controls on the quality and distribution of Syn- to Post-Rift reservoir sands in the Southern Red Sea, offshore Western Yemen

    SciTech Connect

    Carter, J.M.L.

    1995-08-01

    Previous geophysical and drilling results in the southern Red Sea, and the presence of numerous oil seeps, indicate that the syn- to post-rift section is prospective for oil and gas. The relatively high geothermal gradient offshore western Yemen makes intra-salt and post-salt reservoir sands the only viable exploration targets. The quality and distribution of the reservoir sands remains one of the main unknown risk factors, An improved understanding of the controls on deposition of these sands is achieved by use of LandSat data, which provide evidence of a regional tectonic framework involving NE/SW-trending oceanic transform faults which are expressed onshore as strike-slip features, in some cases representing reactivated Precambrian lineaments. These faults are thought to have played two fundamental roles in the Neogene to Recent evolution of the southern Red Sea - firstly by directing clastic input from the rising Yemen Highlands into offshore depocentres, and secondly by influencing the location of salt diapirs sourced by Upper Miocene evaporates. By considering these factors, together with the pattern of heat flow from the developing oceanic rift of the southern Red Sea, it is possible to delineate areas of offshore western Yemen where reservoir characteristics are likely to be most favourable.

  11. AsIII oxidation by Thiomonas arsenivorans in up-flow fixed-bed reactors coupled to As sequestration onto zero-valent iron-coated sand.

    PubMed

    Wan, Junfeng; Klein, Jonathan; Simon, Stephane; Joulian, Catherine; Dictor, Marie-Christine; Deluchat, Véronique; Dagot, Christophe

    2010-09-01

    The combined processes of biological As(III) oxidation and removal of As(III) and As(V) by zero-valent iron were investigated with synthetic water containing high As(III) concentration (10 mg L(-1)). Two up-flow fixed-bed reactors (R1 and R2) were filled with 2 L of sieved sand (d = 3 ± 1 mm) while zero-valent iron powder (d = 76 μm; 1% (w/w) of sand) was mixed evenly with sand in R2. Thiomonas arsenivorans was inoculated in the two reactors. The pilot unit was studied for 33 days, with HRT of 4 and 1 h. The maximal As(III) oxidation rate was 8.36 mg h(-1) L(-1) in R1 and about 45% of total As was removed in R2 for an HRT of 1 h. A first order model fitted well with the As(III) concentration evolution at the different levels in R1. At the end of the pilot monitoring, batch tests were conducted with support collected at different levels in R1. They showed that bacterial As(III) oxidation rate was correlated with the axial length of reactor, which could be explained by biomass distribution in reactor or by bacterial activity. In opposition, As(III) oxidation rate was not stable in R2 due to the simultaneous bacterial As(III) oxidation and chemical removal by zero-valent iron and its oxidant products. However, a durable removal of total As was realized and zero-valent iron was not saturated by As over 33 days in R2. Furthermore, the influence of zero-valent iron and its oxidant corrosion products on the evolution of As(III)-oxidizing bacteria diversity was highlighted by the molecular fingerprinting method of PCR-DGGE using aoxB gene as a functional marker of aerobic As(III) oxidizers.

  12. Sand transport over an immobile gravel substrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were conducted in a laboratory flume channel to evaluate the effects of increasing amounts of sand with an immobile gravel fraction on the sand transport rate and configuration of the sand bed. Knowledge of the movement of sand in gravel beds is important for the management of streams a...

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    We investigated varied coloured Buntsandstein and Rotliegend sandstones in Central Germany (Thuringian Vorderrhön, Altmark) by thermogravimetric/pyrolytic (DEGAS- directly coupled evolved gas analysis) and geochemical (ICP-MS/OES) means to evaluate geochemical/mineralogical characteristics of red bed rocks and their presumably altered, bleached modifications. Commonly bleaching of primary red bed sediments is regarded as a result of fluid-rock reactions by the participation of CO2. This study is performed in the framework of the special research program 'GEOTECHNOLOGIEN' (funded by the German Ministry of Education and Research - BMBF) and is part of two BMBF sponsored projects - 'COMICOR', an analogue study on potential effects of CO2-bearing fluids on Buntsandstein and Rotliegend deposits in Hesse and Thuringia and 'CLEAN', an enhanced gas recovery (EGR) pilot project in cooperation with GDF SUEZ E&P Deutschland GmbH. The intention of CLEAN is to evaluate the feasibility of EGR techniques and the suitability of depleted natural gas reservoirs for potential industrial CO2 sequestration projects. According to rock colour variations two slices of handspecimens (M49, A1) were split into 12 and 15 equally sized samples for analytical work. The medium grained Lower Buntsandstein sample M49 from Thuringia is of fluvial origin and partially bleached with transitions from red (unbleached) to light colours (bleached). Bulk rock geochemistry of red bed and bleached subsamples of M49 are almost similar, including rare earth element (REE) content. Only the content of iron and related metals is depleted in bleached samples compared to the red bed types. All PAAS normalized pattern of M49 show positive Eu and slightly negative Ce anomalies, most likely caused by the presence of apatite and illite in the rocks. The degassing behavior observed by DEGAS of M49 subsamples is mainly controlled by the breakdown of sheet silicates, hydroxides and hydrates, as well as of carbonates and

  14. Evaluation of a Fluidized-Bed Paint Stripper at Red River Army Depot

    DTIC Science & Technology

    1992-04-15

    Incidental Effects of the Fluidized Bed Paint Stripper on Coatings and Metals II- 7 C. Prepare a Technical Report on the Appro- priate Uses of the Fluidized...on the cleaned parts. ° Prepare a technical report on the appropriate uses of the FBPS. ° Train RRAD personnel to operate and maintain the FBPS...establishing operating conditions. The technical report produced from this study will include details on the following: B-17 U Revision No. 0 Section

  15. Red iron-ore beds of Silurian age in northeastern Alabama, northwestern Georgia, and eastern Tennessee

    USGS Publications Warehouse

    Whitlow, Jesse W.

    1962-01-01

    Geological studies have determined the lithology and approximate extent of the red iron ores of Silurian age in the Southeast. Detailed investigations have been made by private companies and government agencies. Most of this work has been in the Birmingham, Ala., district, and the remainder of the region has relatively little study in recent years. 

  16. A wind tunnel study of flow structure adjustment on deformable sand beds containing a surface-mounted obstacle

    NASA Astrophysics Data System (ADS)

    McKenna Neuman, Cheryl; Bédard, OttO

    2015-09-01

    Roughness elements of varied scale and geometry commonly appear on the surfaces of sedimentary deposits in a wide range of planetary environments. They perturb the local fluid flow so that the entrainment, transport, and deposition of particles surrounding each element are fundamentally altered. Fluid dynamists have expended much effort in examining the flow structures surrounding idealized elements mounted on fixed, planar walls. However self-regulation occurs in sedimentary systems as a result of the bed surface undergoing rapid topographic modification with sediment transport, until it reaches a stable form that enhances the net physical roughness. The present wind tunnel study examines how the flow pattern surrounding an isolated cylinder, a problem extensively studied in classical fluid mechanics, is altered through morphodynamic development of a deep well that envelopes the windward face and sidewalls of the roughness element. Spatial patterns in the fluid velocity, turbulence intensity, and Reynolds stress obtained from laser Doppler anemometer measurements suggest that the flow structures surrounding such a cylinder are fundamentally altered through self-regulation of the bed topography as it reaches steady state. For example, flow stagnation and the turbulent dissipation of momentum are substantially increased at selected points surrounding the upwind face and sidewalls of the cylinder, respectively. Along the center line of the wake flow to the rear of the cylinder, several structures arising from flow separation are annihilated by strong upwelling of the airflow exhausted from the terminus of the well. Feedback plays a complex, time-dependent role in this system.

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

    NASA Astrophysics Data System (ADS)

    Bell, C. M.; Suárez, M.

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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

  19. The influence of logjams on largemouth bass (Micropterus salmoides) concentrations on the lower Roanoke River, a large sand-bed river

    USGS Publications Warehouse

    Schenk, Edward R.; McCargo, Jeremy W.; Moulin, Bertrand; Hupp, Cliff R.; Richter, Jean M.

    2015-01-01

    This study examines the relation between logjams and largemouth bass (Micropterus salmoides) on the alluvial sand-bed lower Roanoke River. Disparate data sets from previous bank erosion, fisheries, and large wood studies were used to compare the distribution of largemouth bass with logjam frequency. Logjams are related to the frequency of bank mass wasting increasing from near an upstream dam to the middle reach of the study segment and then decreasing as the river approaches sea level. The highest concentration of largemouth bass and logjams was in the middle reach (110 fish per hour and 21 jams per km). Another measure of largemouth bass distribution, fish biomass density (g h1 ), had a similar trend with logjams and was a better predictor of fish distribution versus logjams (R2= 0.6 and 0.8 and p = 0.08 and 0.02 for fish per hour and g h1 versus logjam, respectively). We theorize that the preference for adult bass to congregate near logjams indicates the use of the jams as feeding areas. The results of a principal component analysis indicate that fish biomass concentration is much more related to logjam frequency than channel geometry (width, depth, and bank height), bed grain size, bank erosion, or turbidity. The results of this research support recent studies on in-channel wood and fisheries: Logjams appear to be important for maintaining, or increasing, both largemouth bass numbers and total biomass of fish in large eastern North American rivers. Persistent logjams, important as habitat, exist where relatively undisturbed river reaches allow for bank erosion inputs of wood and available anchoring locations. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  20. Recovery comparisons--hot nitrogen Vs steam regeneration of toxic dichloromethane from activated carbon beds in oil sands process.

    PubMed

    Ramalingam, Shivaji G; Pré, Pascaline; Giraudet, Sylvain; Le Coq, Laurence; Le Cloirec, Pierre; Baudouin, Olivier; Déchelotte, Stéphane

    2012-02-29

    The regeneration experiments of dichloromethane from activated carbon bed had been carried out by both hot nitrogen and steam to evaluate the regeneration performance and the operating cost of the regeneration step. Factorial Experimental Design (FED) tool had been implemented to optimize the temperature of nitrogen and the superficial velocity of the nitrogen to achieve maximum regeneration at an optimized operating cost. All the experimental results of adsorption step, hot nitrogen and steam regeneration step had been validated by the simulation model PROSIM. The average error percentage between the simulation and experiment based on the mass of adsorption of dichloromethane was 2.6%. The average error percentages between the simulations and experiments based on the mass of dichloromethane regenerated by nitrogen regeneration and steam regeneration were 3 and 12%, respectively. From the experiments, it had been shown that both the hot nitrogen and steam regeneration had regenerated 84% of dichloromethane. But the choice of hot nitrogen or steam regeneration depends on the regeneration time, operating costs, and purity of dichloromethane regenerated. A thorough investigation had been made about the advantages and limitations of both the hot nitrogen and steam regeneration of dichloromethane.

  1. [The red blood system in men during long-term head-down bed rest].

    PubMed

    Ivanova, S M; Morukov, B V; Iarlykova, Iu V; Labetskaia, O I; Levina, A A; Kozinets, G I

    2005-01-01

    Red blood was analyzed in six 25 to 40 yr. old male volunteers in a 120-d head-down bedrest (HDBR) study. The hematological investigation included morphological analyses (erythrocyte count and hemoglobin), and determination of iron turnover, erythrocyte IgA, IgG and IgM, metabolism, lipids and phospholipids, and lipid peroxidation rate (LPO). At the beginning of HDBR (day 7), the erythrocyte count and hemoglobin content were found increased w/o any visible changes in the other parameters. Further exposure to HDBR (days 50-100) resulted in modification of intracellular metabolism in erythrocytes, increases in serum iron, and serum and erythrocyte ferritin. On HDBR days 50 and 100, and post-HDBR day 9, cholesterol was increased, LPO intensified and antioxidant activities inhibited, which suggested destabilization of the cell membrane. Hematological shifts in the bedrested volunteers were of the type and pattern similar to those in cosmonauts who fulfilled extended space missions.

  2. Impact of ozonation pre-treatment of oil sands process-affected water on the operational performance of a GAC-fluidized bed biofilm reactor.

    PubMed

    Islam, Md Shahinoor; Dong, Tao; McPhedran, Kerry N; Sheng, Zhiya; Zhang, Yanyan; Liu, Yang; Gamal El-Din, Mohamed

    2014-11-01

    Treatment of oil sands process-affected water (OSPW) using biodegradation has the potential to be an environmentally sound approach for tailings water reclamation. This process is both economical and efficient, however, the recalcitrance of some OSPW constituents, such as naphthenic acids (NAs), require the pre-treatment of raw OSPW to improve its biodegradability. This study evaluated the treatment of OSPW using ozonation followed by fluidized bed biofilm reactor (FBBR) using granular activated carbon (GAC). Different organic and hydraulic loading rates were applied to investigate the performance of the bioreactor over 120 days. It was shown that ozonation improved the adsorption capacity of GAC for OSPW and improved biodegradation by reducing NAs cyclicity. Bioreactor treatment efficiencies were dependent on the organic loading rate (OLR), and to a lesser degree, the hydraulic loading rate (HLR). The combined ozonation, GAC adsorption, and biodegradation process removed 62 % of chemical oxygen demand (COD), 88 % of acid-extractable fraction (AEF) and 99.9 % of NAs under optimized operational conditions. Compared with a planktonic bacterial community in raw and ozonated OSPW, more diverse microbial communities were found in biofilms colonized on the surface of GAC after 120 days, with various carbon degraders found in the bioreactor including Burkholderia multivorans, Polaromonas jejuensis and Roseomonas sp.

  3. Tar sand

    SciTech Connect

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

    1990-01-01

    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.

  4. 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...

  5. Feedbacks among Floods, Pioneer Woody Vegetation, and Channel Change in Sand-Bed Rivers: Insights from Field Studies of Controlled Flood Releases and Models

    NASA Astrophysics Data System (ADS)

    Wilcox, A. C.; Shafroth, P. B.; Lightbody, A.; Stella, J. C.; Bywater-Reyes, S.; Kiu, L.; Skorko, K.

    2012-04-01

    To investigate feedbacks between flow, geomorphic processes, and pioneer riparian vegetation in sand-bed rivers, we are combining field, hydraulic modeling, and laboratory simulations. Field studies have examined the response of woody riparian seedlings and channel morphology to prescribed dam-released floods that have been designed in part to maintain a native riparian woodland system on the Bill Williams River, Arizona, USA. Through monitoring of floods over a 7-year period, we have observed temporal and spatial variations in channel response. Floods have produced geomorphic and vegetation responses that varied with distance downstream of a dam, with scour and associated seedling mortality closer to the dam and aggradation and burial-induced mortality in a downstream reach with greater sediment supply. We also have observed that as vegetation grows beyond the seedling stage, its stabilizing effect on bars and its drag effect on flow progressively increases, such that floods of similar sizes but at different times may produce markedly different downstream responses as a function of vegetation characteristics. We also observed greater mortality among nonnative Tamarix spp. (tamarisk) seedlings than among native Salix gooddingii (Goodding's willow) seedlings, likely as a result of the greater first-year growth of willow relative to tamarisk. Combining field observations with modeling predictions of local hydraulics for the flood events we have studied is being used to draw linkages between hydraulics, channel change, and plant response at the patch and bar scale. In addition, mechanistic linkages are being examined using a field-scale laboratory stream channel, where seedlings of Tamarix spp. (tamarisk) and Populus fremontii (cottonwood) were planted and subjected to floods with varying sediment feed rate and plant configurations. The floods conveyed by our model channel were generally insufficient to scour the woody seedlings we planted, but changes in bar size and

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  7. Controls of channel morphology and sediment concentration on flow resistance in a large sand-bed river: A case study of the lower Yellow River

    NASA Astrophysics Data System (ADS)

    Ma, Yuanxu; Huang, He Qing

    2016-07-01

    effectively extracted from multisource satellite images. We expect that the empirical methods developed in this study can be used as an effective surrogate in estimation of flow resistance in the large sand-bed rivers like the lower Yellow River.

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

    NASA Astrophysics Data System (ADS)

    Schmidt, Phillip W.; Williams, George E.

    2013-11-01

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

  9. Paleomagnetism of Cretaceous Oceanic Red Beds(CORBs) from Gyangze, Northern Tethys Himalaya: Evidence for introoceanic Subduction System

    NASA Astrophysics Data System (ADS)

    Tan, X.

    2015-12-01

    In the northern Tethys Himalaya, sporadically distributed oceanic red beds (the Chuangde Formation) have been described. The sequence was interpreted to be firstly deposited in the outer continental shelf and upper slope, and later slumped into deep basin. Based on this model, and paleomagnetic data of shallow water deposits from the southern Tethys Himalaya, the CORBs were derived from the northern tip of the passive margin of the greater India. If so, the CORBs would provide more accurate record of the northern extent of the greater India, which is an important parameter for estimating the initial time of India-Asia continental collision and the amount of crustal shortening. The well studied and most accessible section is located in the Chuangde village, about 40km east from the Gyangze city. The formation is about 25m thick, ranging from 84 to 75Ma in age according to fossil records of planktonic foraminiferal species. The lower and upper parts are 2 and 5 meter thick marlstones, respectively, and the middle section is dominated by shale with a few layers of centimeter scale marlstones. Fifty cores were collected from the marlstones of the section, and for the purpose of fold test, 30 more cores were collected from the upper part of the formation from a second section located in the Pulong village, ~10km to the north of the Chuangde village. All samples were subject to stepwise thermal demagnetization. About 60% of the samples yielded interpretable demagnetization results. The middle part of the formation show reversed high temperature component, and the lower and upper parts show normal polarity. The Chuangde section data failed reversal test, because the normal polarity direction is likely not fully resolved from overprint component. However, the well resolved reversal direction from the Chuangde village and the normal direction from Pulong pass both reversal and fold tests. The mean paleomagnetic data indicate a paleolatitude of 10+/-2 degree north, ~2000 km

  10. Acquisition of chemical remanent magnetization during experimental ferrihydrite-hematite conversion in Earth-like magnetic field-implications for paleomagnetic studies of red beds

    NASA Astrophysics Data System (ADS)

    Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J.; Tauxe, Lisa; Qin, Huafeng; Barrón, Vidal; Torrent, José

    2015-10-01

    Hematite-bearing red beds are renowned for their chemical remanent magnetization (CRM). If the CRM was acquired substantially later than the sediment was formed, this severely compromises paleomagnetic records. To improve our interpretation of the natural remanent magnetization, the intricacies of the CRM acquisition process must be understood. Here, we contribute to this issue by synthesizing hematite under controlled 'Earth-like' field conditions (≲ 100 μ T). CRM was imparted in 90 oriented samples with varying inclinations. The final synthesis product appeared to be dominated by hematite with traces of ferrimagnetic iron oxides. When the magnetic field intensity is ≳ 40 μ T, the CRM records the field direction faithfully. However, for field intensities ≲ 40 μ T, the CRM direction may deviate considerably from that of the applied field during synthesis. The CRM intensity normalized by the isothermal remanent magnetization (CRM/IRM@2.5 T) increases linearly with the intensity of growth field, implying that CRM could potentially be useful for relative paleointensity studies if hematite particles of chemical origins have consistent properties. CRM in hematite has a distributed unblocking temperature spectrum from ∼200 to ∼650 °C, while hematite with a depositional remanent magnetization (DRM) has a more confined spectrum from ∼ 600to 680 °C because it is usually coarser-grained and more stoichiometric. Therefore, the thermal decay curves of CRM with their concave shape are notably different from their DRM counterparts which are convex. These differences together are suggested to be a potential discriminator of CRM from DRM carried by hematite in natural red beds, and of significance for the interpretation of paleomagnetic studies on red beds.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  12. Sidewinding snakes on sand

    NASA Astrophysics Data System (ADS)

    Marvi, Hamidreza; Dimenichi, Dante; Chrystal, Robert; Mendelson, Joseph; Goldman, Daniel; Hu, David; Georgia Tech and Zoo Atlanta Collaboration

    2012-11-01

    Desert snakes such as the rattlesnake Crotalus cerastes propel themselves over sand using sidewinding, a mode of locomotion relying upon helical traveling waves. While sidewinding on hard ground has been described, the mechanics of movement on more natural substrates such as granular media remain poorly understood. In this experimental study, we use 3-D high speed video to characterize the motion of a sidewinder rattlesnake as it moves on a granular bed. We study the movement both on natural desert sand and in an air-fluidized bed trackway which we use to challenge the animal on different compactions of granular media. Particular attention is paid to rationalizing the snake's thrust on this media using friction and normal forces on the piles of sand created by the snake's body. The authors thank the NSF (PHY-0848894), Georgia Tech, and the Elizabeth Smithgall Watts endowment for support. We would also like to thank Zoo Atlanta staff for their generous help with this project.

  13. The Yampa Bed - A Regionally Extensive Tonstein in the Williams Fork Formation, Northwestern Piceance Creek and Southern Sand Wash Basins, Colorado

    USGS Publications Warehouse

    Brownfield, Michael E.; Johnson, Edward A.

    2008-01-01

    A regionally persistent and distinctive unit of Upper Cretaceous age is here formally named the Yampa Bed of the Williams Fork Formation for exposures in the Yampa, Danforth Hills, and Grand Hogback coal fields, Moffat and Routt Counties, northwest Colorado; the name is derived from the Yampa River valley. The type section was measured in the NE? SW? sec. 6, T. 5 N., R. 91 W., about 8 miles south of Craig, Colo., where the bed is 38 inches thick and lies within the C-D coal bed in the lower part of the Williams Fork Formation, about 165 feet above the Trout Creek Sandstone Member of the Iles Formation. The Yampa Bed is dated at 72.2 ? .1 mega-annum using the K-Ar method. Regionally, the Yampa Bed is a 0.5- to 5-ft-thick, regionally persistent tonstein that can be readily identified in several different lithofacies in the lower part of the Williams Fork Formation. The unit is useful as a regional datum in the correlation of facies within the Williams Fork, and it is easily recognized on geophysical logs by its low resistivity response. Evidence suggests that it is a diagenetically altered airfall ash.

  14. Integration of bed characteristics, geochemical tracers, current measurements, and numerical modeling for assessing the provenance of beach sand in the San Francisco Bay Coastal System

    USGS Publications Warehouse

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

    2013-01-01

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

  15. Adsorption of Cu, Ag, and other metals on Fe-oxides as a control on elemental composition of stratiform and red bed copper deposits

    SciTech Connect

    Rose, A.W.; Bianchi, G.C.

    1985-01-01

    In low-temperature red bed and stratiform Cu deposits like Zambia-Zaire, Kupferschiefer, and Redstone, Cu is accompanied by various combinations of Ag, Co, Pb and Zn, and appears to be emplaced during diagenesis. Red bed sediments near deposits in Pennsylvania and beneath the Redstone deposit are strongly depleted in Cu but show little change in Pb, Zn, Ni and Co. Formation of cuprous chloride complexes under slightly reducing conditions allow solubility of Cu, but these solutions also transport Pb, Zn, Ni and Co. The effect of adsorption by Fe-oxides in the red beds as a control on metal ratios has been tested by experiments on 0.5 ppm Cu, Ag, Pb, Zn, Ni and Co with 0.8 g/1 goethite at 25/sup 0/C in 1 M NaCl. Under oxidized conditions (air),the pH values above which more than 50% of the metals are adsorbed are: Cu 5.0, Pb 5.5, Zn 6.5, Co 7.5, Ni 7.8, and Ag > 9. For more reduced conditions near the Fe/sup 2 +/-goethite boundary, the 50% adsorption values for Pb, Zn, Co, Ni and Ag are decreased by 0.5 to 1 pH unit, perhaps because of competition with Fe/sup 2 +/, but Cu (as CuCl/sub 2//sup -/ and CuCl/sub 3//sup 2 -/) shows adsorption of only about 20% at pH 5, 25% at pH 6, 35% at pH 7, and 100% at pH 8. At 50/sup 0/C, adsorption at pH 5 and 6 is about 10% and 20%, respectively, for Cu. By changes in Eh, pH, temperature, and molality of Cl and other species such as SO/sub 4/, CO/sub 3/, Ca, and Mg, it appears that various combinations of metals can be mobilized or left immobile. The time of mobilization and nature of Fe-oxide may also be critical.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 analytic...

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Northwest Vietnam mainly consists of the Song Da terrane, which is bounded to the east by the NW-oriented Ailao Shan/Red River (ASRR) fault system, interpreted to be the southwest margin of the South China Block, and the NW-oriented Song Ma fault. The northern termination of the Song Da terrane is considered to be where the NE-oriented, right lateral Dien Bien Phu fault intersects the ASRR. Whether the Song Da terrane is part of the extruded Indochina Block, paleomagnetic data from which suggest some 10°+ southward latitudinal displacement, can be evaluated with paleomagnetic data from rocks of the appropriate age. Our paleomagnetic sampling concentrated on the Upper Cretaceous Yen Chau Formation, which unconformably overlies Paleozoic and Triassic sedimentary rocks. The Yen Chau Formation is locally up to about 1300 m thick, and is characterized by medium to thick bedded, coarse to fine-grained sandstones and siltstones, all of which are partially cemented by hematite. Samples were collected from 10 localities using a portable drill, with 6 to 19 sites collected per locality, and 7 to 15 samples collected from each site. This approach allows evaluation of the integrity of the remanence at the locality level, where, presumably, considerable time is recorded in each section. Each locality is a homoclinal road cut exposure, with bedding dips varying from sub-horizontal to moderately overturned. NRM intensities range from about 0.7 mA/m to about 25 mA/m; values which are relatively low in comparison to many red beds. A varied response to alternating field (AF) demagnetization indicates that magnetite carries a considerable (over 50 percent) of the remanence; the finest grained samples of relatively high NRM intensity reveal little response to AF treatment, indicating a dominance by hematite, as also supported by three-component IRM thermal demagnetization. Samples with the highest NRM intensities and the least contribution by magnetite respond favorably to thermal

  18. Paleomagnetism of Cretaceous Oceanic Red Beds (CORBs) from Gyangze, northern Tethys Himalaya: Evidence for Intra-oceanic Subduction System and Southern Paleolatitute Limit for the Lhasa Block

    NASA Astrophysics Data System (ADS)

    Tan, Xiaodong

    2016-04-01

    In the northern Tethys Himalaya, sporadically distributed Cretaceous oceanic red beds (CORBs, the Chuangde Formation) have been described. The sequence was interpreted to be firstly deposited in the outer continental shelf and upper slope, and later slumped into deep basin. Based on this model, and paleomagnetic data of shallow water deposits from the southern Tethys Himalaya, the CORBs were derived from the northern tip of the passive margin of the greater India. If so, the CORBs would provide more accurate record of the northern extent of the greater India, which is an important parameter for estimating the initial time of India-Asia continental collision and the amount of crustal shortening. The well studied and most accessible section is located in the Chuangde village, about 40km east from the Gyangze city. The formation is about 25m thick, ranging from 84 to 75Ma in age according to fossil records of planktonic foraminiferal species. The lower and upper parts are 2 and 5 meter thick marlstones, respectively, and the middle section is dominated by shale with a few layers of centimeter scale marlstones. Fifty cores were collected from the marlstones of the section, and for the purpose of fold test, 30 more cores were collected from the upper part of the formation from a second section located in the Pulong village, ~3km to the northeast of the Chuangde village. All samples were subject to stepwise thermal demagnetization. About 60% of the samples yielded interpretable demagnetization results. The bottom of the upper part of the formation show reversed high temperature component, and the rest of the upper part and the lower part show normal polarity. The Chuangde section data failed reversal test, because the normal polarity direction is likely not fully resolved from overprint component. However, the well resolved reversal direction from the Chuangde village and the normal direction from Pulong pass both reversal and fold tests. The mean paleomagnetic data

  19. Analysis of naticid gastropod predation across the trans-Arctic invasion in the Tjörnes beds, Iceland, and the Red Crag Formation, East Anglia, England

    NASA Astrophysics Data System (ADS)

    Neely, Samuel H.; Kelley, Patricia H.

    2016-04-01

    Invasive species are wreaking havoc on modern ecosystems; however, species invasions are not new threats to ecosystems. The fossil record allows conservationists to acquire deep-time perspectives on long-term effects of natural invasions before anthropogenic impacts. Drill holes from invasive naticid gastropod predators on bivalve prey can be quantified to provide evidence of the impact of these invasive predators on ecosystems. An asymmetrical faunal interchange, known as the trans-Arctic invasion (TAI), occurred between the Pacific and Atlantic oceans during the Pliocene (˜3.5 Ma) because of the opening of the Bering Strait. This interchange could have changed naticid gastropod drilling predation on bivalves due to the migration of Pacific fauna into the Atlantic Ocean. The Tjörnes locality of northeast Iceland well characterizes the TAI because this site has preserved genera in three distinct levels that divide the invasion into the pre-invasion (Tapes and Mactra zones) and the post-invasion (Serripes zone). Temporal comparisons can be made between these pre- and post-invasion zones to analyze drilling predation across the TAI. Spatial comparisons of drilling predation in the post-invasion deposits can be made by correlating the Serripes zone (3.6-2.6 Ma) to the Red Crag Formation (2.54 Ma) of East Anglia, England, because these localities are of similar age and contain similar taxa. Specimens from the Tjörnes Beds, Iceland, were analyzed in collections housed at the Icelandic Institute of Natural History. Red Crag Formation specimens were analyzed at the Academy of Natural Sciences at Drexel University, Philadelphia, PA. Height and length of bivalve specimens were measured. The occurrence of complete and incomplete (unsuccessful) drill holes and drill hole diameter were recorded for all whole bivalves. Drilling frequency (DF = % mortality) and prey effectiveness (PE = % of attempted drill holes that were incomplete) were calculated. Icelandic samples

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

    NASA Astrophysics Data System (ADS)

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

    1999-03-01

    The Eriksfjord Group comprises ~3000 m of lavas and sediments rapidly deposited in a rift which developed within an Andean-type batholith in juxtaposition to the southern margin of the Laurentian Shield in South Greenland at ca. 1300 Ma. The lavas have been shown to preserve a detailed record of the geomagnetic field at the time of eruption, incorporating normal, reversed and transitional directions. This study has examined the magnetic properties of the intervening red sediments. They are found to possess a diagenetic remanence imparted by mediating fluids at later times. The impact of diagenesis is stratigraphically controlled: the base of the rift infill has magnetizations partially resident in magnetite which are either unstable to thermal cleaning or record a single polarity `B' magnetization (D/I = 284/67°, 31 samples, α95 = 5.5°, palaeopole at 244.1°E, 47.5°N, dp/dm = 7.5/9.1° ). This corresponds in polarity, and closely in direction, to remanence observed in mid-Gardar gabbro giant dykes and dyke swarms emplaced along the axis of the rift system at ca. 1160 Ma the causative diagenetic magnetite appears to have grown from hydrothermal systems motivated by this magmatism in a sealed reservoir setting within the lower part of the rift infill. The Ilímaussaq alkaline igneous complex was emplaced into the southern extension of the rift at ca. 1130 Ma and possesses a dual polarity magnetization (D/I = 327/81°, α95 = 6.4°, 10 sites). Eriksfjord lavas within the thermal aureole are overprinted to varying degrees by comparable magnetizations with steep inclinations. The mean pole position (283°E, 71°N, dp/dm = 12/12° ) lies near the apex of an apparent polar wander loop incorporating the Gardar Track (ca. 1300-1140 Ma) and the Keweenawan Track (ca. 1115-1050 Ma). Magnetizations in the Eriksfjord sedimentary succession have not been significantly reset by emplacement of the Ilímaussaq complex, but higher levels of the rift infill are dominated by an `A

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

    PubMed

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

    2012-09-01

    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.

  2. Biomass development in slow sand filters.

    PubMed

    Campos, L C; Su, M F J; Graham, N J D; Smith, S R

    2002-11-01

    Microbial biomass development in the sand and schmutzdecke layer was determined in two full-scale slow sand filters, operated with and without a light excluding cover. A standard chloroform fumigation-extraction technique was adapted to routinely measure microbial biomass concentrations in the sand beds. Sand was sampled to a depth of 10 cm and schmutzdecke was also collected at the same random positions on the uncovered filter. Interstitial microbial biomass in the uncovered sand bed increased with time and decreased with sampling depth. There was a small accumulation of sand biomass with time in the covered filter, but no relationship was apparent between biomass concentration and depth in this filter. Schmutzdecke did not develop on the covered filter and was spatially highly variable in the uncovered condition compared to the consistent patterns observed in interstitial biomass production. It is speculated that microbial biomass in the sand of uncovered filters is largely related to carbon inputs from photosynthetic activity in the schmutzdecke and involves mechanisms that spatially distribute carbon substrate from the schmutzdecke to the sand. However, total organic carbon and dissolved organic carbon removals were similar in both filters suggesting that relatively small biomass populations in covered filters are sufficient to remove residual labile carbon during advanced water treatment and little further advantage to water purification and organic carbon removal is gained by the increased production of biomass in uncovered slow sand filter beds.

  3. Effects of silt loading on turbulence and sand transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transport of bed material and fluid turbulence are affected by many factors, including the fine sediment load being carried in a channel. Current research has focused on sand-sized particles introduced to gravel beds, while the effect of silt load on sand transport has received less attention. ...

  4. Sands-on Learning.

    ERIC Educational Resources Information Center

    Vandervoort, Frances S.

    1989-01-01

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

  5. Paleomagnetism of Late Jurassic to Early Cretaceous red beds from the Cardamom Mountains, southwestern Cambodia: Tectonic deformation of the Indochina Peninsula

    NASA Astrophysics Data System (ADS)

    Tsuchiyama, Yukiho; Zaman, Haider; Sotham, Sieng; Samuth, Yos; Sato, Eiichi; Ahn, Hyeon-Seon; Uno, Koji; Tsumura, Kosuke; Miki, Masako; Otofuji, Yo-ichiro

    2016-01-01

    Late Jurassic to Early Cretaceous red beds of the Phuquoc Formation were sampled at 33 sites from the Sihanoukville and Koah Kong areas of the Phuquoc-Kampot Som Basin, southwestern Cambodia. Two high-temperature remanent components with unblocking temperature ranging 650°-670 °C and 670-690 °C were identified. The magnetization direction for the former component (D = 5.2 °, I = 18.5 ° with α95 = 3.1 ° in situ) reveals a negative fold test that indicates a post-folding secondary nature. However, the latter component, carried by specular hematite, is recognized as a primary remanent magnetization. A tilt-corrected mean direction of D = 43.4 °, I = 31.9 ° (α95 = 3.6 °) was calculated for the primary component at 11 sites, corresponding to a paleopole of 47.7°N, 178.9°E (A95 = 3.6 °). When compared with the 130 Ma East Asian pole, a southward displacement of 6.0 ° ± 3.5 ° and a clockwise rotation of 33.1 ° ± 4.0 ° of the Phuquoc-Kampot Som Basin (as a part of the Indochina Block) with respect to East Asia were estimated. This estimate of the clockwise rotation is ∼15° larger than that of the Khorat Basin, which we attribute to dextral motion along the Wang Chao Fault since the mid-Oligocene. The comparison of the herein estimated clockwise rotation with the counter-clockwise rotation reported from the Da Lat area in Vietnam suggests the occurrence of a differential tectonic rotation in the southern tip of the Indochina Block. During the southward displacement of the Indochina Block, the non-rigid lithosphere under its southern tip moved heterogeneously, while the rigid lithosphere under the Khorat Basin moved homogeneously.

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

    USGS Publications Warehouse

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    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

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

    SciTech Connect

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

    1992-04-01

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

  9. Prediction of sand transport over immobile gravel from supply limited to capacity conditions.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The prediction of the transport of sand in armored gravel reaches downstream of dams is complicated by variable bed conditions ranging from sand transported through gravel to sand in transport over buried gravel. Knowledge of the rate of sand transport in these conditions, however, is necessary for...

  10. Bed Bugs

    EPA Pesticide Factsheets

    Prevent, identify, and treat bed bug infestations using EPA’s step-by-step guides, based on IPM principles. Find pesticides approved for bed bug control, check out the information clearinghouse, and dispel bed bug myths.

  11. Reovirus removal and inactivation by slow-rate sand filtration.

    PubMed Central

    McConnell, L K; Sims, R C; Barnett, B B

    1984-01-01

    Laboratory column studies were conducted at the Utah Water Research Laboratory, Logan, Utah, to evaluate reovirus removal from drinking water supplies by slow-rate sand filtration (SSF). Columns, constructed to simulate a full-scale SSF field operation, were inoculated with reovirus at ca. 1,000-times-greater concentrations than those typically found in domestic sewage. Reovirus removal and inactivation were investigated as functions of filter maturity and other filter sand characteristics. Reovirus removal studies demonstrated that the SSF process is capable of reducing reovirus in influent water by a minimum of 4 log concentration units under certain conditions of water quality, flow rate, and sand bed construction. Infectious reovirus was not detected in effluent samples from any of the sand beds studied, after inoculation of the SSF columns; therefore, removal efficiencies were not affected significantly by characteristics, including age, of the two filter sands evaluated. Studies conducted with radioactively labeled reovirus demonstrated that reovirus removed from influent water was distributed throughout the entire length of the filter beds. Concentrations of reovirus in the filter sands decreased with increasing bed depth. The greatest removal occurred in the top few centimeters of all sand beds. No infectious reovirus could be detected in clean or mature sand bed media, indicating that reoviruses were inactivated in the filter. PMID:6508290

  12. Improved lignin pyrolysis for phenolics production in a bubbling bed reactor--Effect of bed materials.

    PubMed

    Li, Dongbing; Briens, Cedric; Berruti, Franco

    2015-01-01

    Lignin pyrolysis was studied in a bubbling fluidized bed reactor equipped with a fractional condensation train, using nitrogen as the fluidization gas. The effect of different bed materials (silica sand, lignin char, activated lignin char, birch bark char, and foamed glass beads) on bio-oil yield and quality was investigated for a pyrolysis temperature of 550 °C. Results how that a bed of activated lignin char is preferable to the commonly used silica sand: pyrolysis of Kraft lignin with a bed of activated lignin char not only provides a pure char product, but also a higher dry bio-oil yield (with a relative increase of 43%), lower pyrolytic water production, and better bio-oil quality. The bio-oil obtained from Kraft lignin pyrolysis with a bed of activated lignin char has a lower average molecular weight, less tar, more phenolics, and less acidity than when sand is used as bed material.

  13. Bed bugs.

    PubMed

    Foulke, Galen T; Anderson, Bryan E

    2014-09-01

    The term bed bug is applied to 2 species of genus Cimex: lectularius describes the common or temperate bed bug, and hemipterus its tropical cousin. Cimex lectularius is aptly named; its genus and species derive from the Latin words for bug and bed, respectively. Though the tiny pest is receiving increased public attention and scrutiny, the bed bug is hardly a new problem.

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

    SciTech Connect

    Johnson, C.L.

    1984-04-01

    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.

  15. Three-dimensional mapping of red stingray ( Dasyatis akajei) movement with reference to bottom topography

    NASA Astrophysics Data System (ADS)

    Otaki, Takayoshi; Hamana, Masahiro; Tanoe, Hideaki; Miyazaki, Nobuyuki; Shibuno, Takuro; Komatsu, Teruhisa

    2015-06-01

    Most demersal fishes maintain strong relations with bottom substrates and bottom depths and/or topography during their lives. It is important to know these relations to for understand their lives. In Tokyo Bay, red stingray, Dasyatis akajei, classified as near-threatened species by IUCN, has increased since the 1980s. It is a top predator and engages in ecosystem engineer by mixing the sand bed surface through burring behavior, and greatly influences a coastal ecosystem. It is reported that this species invades in plage and tidal flats and has sometimes injured beachgoers and people gathering clams in Tokyo bay. Thus, it is necessary to know its behavior and habitat use to avoid accidents and to better conserve the biodiversity of ecosystems. However, previous studies have not examined its relationship with the bottom environment. This study aims to describe its behavior in relation to the bottom environment. We sounded three dimensional bottom topography of their habitat off Kaneda Cove in Tokyo Bay with interferometric sidescan sonar system and traced the movement of red stingrays by attaching a data logger system to survey their migration. The results revealed that red stingray repeated vertical movement between the surface and bottom, and used not only sand beds but also rocky beds.

  16. Impact on Granular Beds

    NASA Astrophysics Data System (ADS)

    van der Meer, Devaraj

    2017-01-01

    The impact of an object on a granular solid is an ubiquitous phenomenon in nature, the scale of which ranges from the impact of a raindrop onto sand all the way to that of a large asteroid on a planet. Despite the obvious relevance of these impact events, the study of the underlying physics mechanisms that guide them is relatively young, with most work concentrated in the past decade. Upon impact, an object starts to interact with a granular bed and experiences a drag force from the sand. This ultimately leads to phenomena such as crater formation and the creation of a transient cavity that upon collapse may cause a jet to appear from above the surface of the sand. This review provides an overview of research that targets these phenomena, from the perspective of the analogous but markedly different impact of an object on a liquid. It successively addresses the drag an object experiences inside a granular bed, the expansion and collapse of the cavity created by the object leading to the formation of a jet, and the remarkable role played by the air that resides within the pores between the grains.

  17. Fluidized Bed Boiler Assessment for Navy Applications

    DTIC Science & Technology

    1986-11-01

    inertia and latent heat stored in the bed material allow newly added fuel to ignite quickly and evenly; even wet or low-quality fuels can be burned...about 97% inert bed material (e.g., sand) and 3% fuel. The upper bed is composed of finely ground sulfur sorbent and is where desulfurization of...can be burned without the need of the expensive back-end desulfurization equipment. In fact, most FBC boilers can practically burn all combustible

  18. Submarine sand ridges and sand waves in the eastern part of the China Sea

    NASA Astrophysics Data System (ADS)

    Wu, Ziyin; Li, Shoujun; Shang, Jihong; Zhou, Jieqiong; Zhao, Dineng; Liang, Yuyang

    2016-04-01

    Integrated with multi-beam and single-beam echo sounding data, as well as historical bathymetric data, submarine bathymetric maps of the eastern part of the China Sea, including the Bohai Sea, Huanghai Sea, and East China Sea, are constructed to systematically study submarine sand ridges and sand waves in the eastern part of the China Sea, combined with high-resolution seismic, sub-bottom profile and borehole data. Submarine sand ridges are extraordinarily developed in the eastern part of the China Sea, and 7 sand ridge areas can be divided from north to south, that is, the Laotieshan Channel sand ridge area in the Bohai Sea, the Korea Bay sand ridge area in the southern Huanghai Sea, the sand ridge area in the eastern Huanghai islands and the Huanghai Troughs, the Jianggang sand ridge area in the western Huanghai Sea, the sand ridge area in the East China Sea shelf, and the sand ridge and sand wave area in the Taiwan Strait and Taiwan Banks. The distribution area of the sand ridges and sand waves covers more than 450,000 km2, wherein ~10,000 km2 in the Bohai Bay, ~200,000 km2 in the Huanghai Sea, ~200,000 km2 in the East China Sea shelf, and ~40,000 km2 in the Taiwan Strait and Taiwan Banks, respectively. The great mass of sand ridges are distributed within water depth of 5-160 m, with a total length of over 160 km and a main width of 5-10 km. The inner structure of the sand ridges presents features of high-angle inclined beddings, with main lithology of sands, sand-mud alternations partly visible, and a small number of mud cores. Dating results indicate that the sand ridges in the eastern part of the China Sea are mainly developed in the Holocene. Sea-level variation dominates the sand ridge evolution in the eastern part of the China Sea since the LGM, and the sand ridges developed in the area of < 60m water depth are appeared in bad activity, meanwhile sand ridges with good activity are still developed in large scale.

  19. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2011-01-01

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

  20. Infiltration of Sand Into Gravel Riverbeds With Alternate Bar Topography

    NASA Astrophysics Data System (ADS)

    Leonardson, R.; Wydzga, M. A.; Venditti, J. G.; Dietrich, W. E.; Stacey, M. T.; Dracup, J. A.

    2006-12-01

    The hyporheic zone, which is comprised of the interconnected pore spaces in the bed of gravel rivers, plays a variety of roles in river health. It serves as a nutrient reservoir and refuge for aquatic organisms; supports surface water-groundwater exchange, which can mitigate flooding and improve water supply reliability; and stores organic matter, heavy metals, and other pollutants. When fine sediment (sand and silt) fills the pore spaces of the hyporheic zone, these functions are compromised. A number of one-dimensional laboratory studies have explored infiltration of sand into stable, flat (plane-bed), gravel riverbeds. The depth and volumetric content of sand infiltrated under such conditions are functions of sediment supply and the grain size distributions of the bed (gravel) and the sand in bedload. This study examines whether the relationships established in plane-bed experiments suffice to explain infiltration into a bed with alternate-bar topography. We present results from an infiltration experiment performed on a 2.7m x 55m laboratory flume at St. Anthony Falls Laboratory in Minneapolis. In this experiment, sand (D50 = 0.4mm) was infiltrated into a gravel (D50 = 9.2mm) bed with alternate bars, under low flow (35 lps). After infiltration, the bed was excavated at 3-6 sites in each of 5 cross-sections, chosen to represent a variety of topographic and flow conditions (e.g. head of bar, top of bar and deep channel, cross-channel). Bed samples are analyzed for depth of infiltration, sand content, and grain size distribution. We present the spatial patterns of depth and content of sand infiltrated, in relation to bed surface topography and surface water flow path. Ongoing research will couple the characteristics of this spatial pattern with sediment routing.

  1. Lizard locomotion on weak sand

    NASA Astrophysics Data System (ADS)

    Goldman, Daniel

    2005-03-01

    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 μm glass spheres of fixed volume fraction φ 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 φ 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.

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

    USGS Publications Warehouse

    dePaul, Vincent T.; Szabo, Zoltan

    2007-01-01

    This investigation is the first regionally focused study of the presence of natural radioactivity in water from the Vincentown and Wenonah-Mount Laurel aquifers, Englishtown aquifer system, and the Hornerstown and Red Bank Sands. Geologic materials composing the Vincentown and Wenonah-Mount Laurel aquifers and the Hornerstown and Red Bank Sands previously have been reported to contain radioactive (uranium-enriched) phosphatic strata, which is common in deposits from some moderate-depth coastal marine environments. The decay of uranium and thorium gives rise to natural radioactivity and numerous radioactive progeny, including isotopes of radium. Naturally occurring radioactive isotopes, especially those of radium, are of concern because radium is a known human carcinogen and ingestion (especially in water used for drinking) can present appreciable health risks. A regional network in southwestern and south-central New Jersey of 39 wells completed in the Vincentown and Wenonah-Mount Laurel aquifers, the Englishtown aquifer system, and the Hornerstown and Red Bank Sands was sampled for determination of gross alpha-particle activity; concentrations of radium radionuclides, major ions, and selected trace elements; and physical properties. Concentrations of radium-224, radium-226, and radium-228 were determined for water from 28 of the 39 wells, whereas gross alpha-particle activity was determined for all 39. The alpha spectroscopic technique was used to determine concentrations of radium-224, which ranged from less than 0.5 to 2.7 pCi/L with a median concentration of less than 0.5pCi/L, and of radium-226, which ranged from less than 0.5 to 3.2 pCi/L with a median concentration of less than 0.5 pCi/L. The beta-counting technique was used to determine concentrations of radium-228. The concentration of radium-228 ranged from less than 0.5 to 4.3 pCi/L with a median of less than 0.5. Radium-228, when quantifiable, had the greatest concentration of the three radium

  3. Sand dunes as migrating strings

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  4. Sand dunes as migrating strings.

    PubMed

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

    2013-05-01

    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.

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

    SciTech Connect

    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

    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.

  6. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2013-01-01

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

  7. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2012-01-01

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

  8. Red Bluff, Marion County, Mississippi: a Citronelle braided-stream deposit

    SciTech Connect

    Smith, M.L.; Meylan, M.A.

    1983-09-01

    Red Bluff is an erosional escarpment located on the western margin of the Pearl River flood plain in northwestern Marion County, Mississippi. The sand grains are composed primarily of quartz, with small amounts of heavy minerals and feldspar. The gravel is composed of varying percentages of chert, flint, jasper, rip-up clasts, quartz, and tripoli, including a small fraction of silicified Paleozoic fossils. Grain-size analysis of the sediment and investigation of the sedimentary structures suggest a braided-fluvial environment of deposition. The most conspicuous sedimentary structures at Red Bluff are graded bedding, low-angle to medium-angle cross-bedding, and well-developed paleochannels. A statistical comparison (discriminant analysis) of the seven most abundant heavy minerals of Red Bluff, with the same suite of heavy minerals found at the type section of the Citronelle Formation (Pliocene-Pleistocene), and outcrops of a known Miocene coarse clastic unit indicates a correlation of Red Bluff to the Citronelle Formation. These heavy minerals are kyanite, staurolite, rutile, tourmaline, zircon, black opaques (primarily ilmenite and magnetite), and white opaques (primarily leucoxene). The suite of heavy minerals present at Red Bluff belongs to the east Gulf province. This metamorphic assemblage of heavy minerals implies the source area of the sediments at Red Bluff to be the southern Appalachians. The silicified pebble-size Devonian-Mississippian fossils were derived most likely from formations flanking the southern Appalachians in northern Alabama.

  9. Wet sand flows better than dry sand

    NASA Astrophysics Data System (ADS)

    Wagner, Christian

    2015-03-01

    Wet sand that does not contain too much water is known to be stiff enough to build sand castles or in physical words has a significant yield stress. However, we could recently show that there are quite a few conditions under which such wet sand opposes less resistant to flow than its dry counterpart. This effect might have been already known to the old Egyptians: The Ancient painting of El Bersheh at the tomb of Tehutihetep shows that there was liquid poured in front of the sledge that was used to transport heavy weight stones and statues. While archeologist have attributed this to a sacral ceremony, our data clearly show that wetting the sand ground drastically decreases the effective sliding friction coefficient. We first study the stress-strain behavior of sand with and without small amounts of liquid under steady and oscillatory shear. Using a technique to quasistatically push the sand through a tube with an enforced parabolic (Poiseuille-like) profile, we minimize the effect of avalanches and shear localization. We observe that the resistance against deformation of the wet (partially saturated) sand is much smaller than that of the dry sand, and that the latter dissipates more energy under flow. Second we show experimentally that the sliding friction on sand is greatly reduced by the addition of some--but not too much--water. The formation of capillary water bridges increases the shear modulus of the sand, which facilitates the sliding.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  12. The extraction of bitumen from western oil sands: Volume 1. Final report

    SciTech Connect

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

    1997-11-26

    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.

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

    SciTech Connect

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

    1997-11-26

    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.

  14. Payload Bay and Great Western Sand Sea, Algeria, Africa

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Patterns of yellow and orange dunes of the Great Western Sand Sea of Algeria (29.5N, 1.5W) contrast with the black folded sedimentary rocks in the central Sahara Desert. A small dry riverbed, along the line between the thick sands and the black rocks brings in sediment from the Atlas Mountains of Morocco. Southwest winds blow sand from the bed to form a thick sand sheet on the downwind side of the river to contrast with the thin upwind dune strips.

  15. Particle Dynamics and Gravel-Bed Adjustments

    DTIC Science & Technology

    1993-05-01

    detecteur des movement des sediments fins. Societe hydrotechnique de France. Transport Hydraulique et Decantation des Materiaux Solides. pp3 9 p. 38...Kirkby, MJ. (Eds.) Channel Ndork Hydrology. Wiley. Chichester. pp 129-173. 67. Lapointe, M.F. (1992) Burst-like sediment suspension events in a sand bed...alluvial sand suspension by eddy correlation. Earth Surface Processes & Landforms, 11, (in press). 69. Soulsby, R.L. (1983) The bottom boundary layer of

  16. Scaling of sand flux over bedforms- experiments to field scale

    NASA Astrophysics Data System (ADS)

    McElroy, B. J.; Mahon, R. C.; Ashley, T.; Alexander, J. S.

    2015-12-01

    Bed forms are one of the few geomorphic phenomena whose field and laboratory geometric scales have significant overlap. This is similarly true for scales of sediment transport. Whether in the lab or field, at low transport stages and high Rouse numbers where suspension is minimal, sand fluxes scale nonlinearly with transport stage. At high transport stages, and low Rouse numbers where suspension is substantial, sand transport scales with rouse number. In intermediate cases deformation of bed forms is a direct result of the exchange of sediment between the classically suspended and bed load volumes. These parameters are straightforwardly measured in the laboratory. However, practical difficulties and cost ineffectiveness often exclude bed-sediment measurements from studies and monitoring efforts aimed at estimating sediment loads in rivers. An alternative to direct sampling is through the measurement of evolution of bed topography constrained by sediment-mass conservation. Historically, the topographic-evolution approach has been limited to systems with negligible transport of sand in suspension. As was shown decades ago, pure bed load transport is responsible for the mean migration of trains of bed forms when no sediment is exchanged between individual bed forms. In contrast, the component of bed-material load that moves in suspension is responsible for changes in the size, shape, and spacing of evolving bed forms; collectively this is called deformation. The difference between bed-load flux and bed-material-load flux equals the flux of suspended bed material. We give a partial demonstration of this using available field and laboratory data and comparing them across geometric and sediment transport scales.

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

    USGS Publications Warehouse

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

    1996-01-01

    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.

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

    SciTech Connect

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

    1989-03-01

    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.

  19. The Cenozoic rotational extrusion of the Chuan Dian Fragment: New paleomagnetic results from Paleogene red-beds on the southeastern edge of the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Tong, Ya-Bo; Yang, Zhenyu; Wang, Heng; Gao, Liang; An, Chun-Zhi; Zhang, Xu-Dong; Xu, Ying-Chao

    2015-09-01

    Paleomagnetic studies were conducted on the Eocene and Oligocene strata at the western part of the Chuan Dian Fragment in order to describe the crustal deformation induced by continuous penetration of the Indian plate into Eurasia during the late Cenozoic. High-temperature magnetic components with unblocking temperatures of ~ 680 °C were isolated, and positive fold and/or reversal tests reveal the primary nature of the magnetization. The tilt-corrected site-mean directions obtained from the Oligocene and middle-early Eocene strata are, respectively, Ds = 200.9°, Is = - 31.3°, k = 52.8, α95 = 7.7° and Ds = 29.7°, Is = 32.0°, k = 44.9, α95 = 5.6°. Comparison of these results with previous paleomagnetic data from the Chuan Dian Fragment shows that the western and central parts of the Chuan Dian Fragment experienced ~ 20° integral clockwise rotation relative to East Asia since the middle Miocene. However, the eastern part of the Chuan Dian Fragment has experienced different rotational deformation relative to East Asia since the Pliocene, because of the intense regional crustal deformation and activity on fault systems. The eastern boundary of the Chuan Dian Fragment was bounded by the Yuanmou-Luezhijiang left lateral strike-slip fault prior to the Pliocene, and then substituted by the Xiaojiang left lateral strike-slip fault since the Pliocene, due to the eastwards spreading of the clockwise rotational movement of the Chuan Dian Fragment. The evolutionary characteristics of the Ailaoshan-Red River and Xianshuihe-Xiaojiang strike-slip faults were controlled by the difference between the clockwise rotational extrusion velocities of the Chuan Dian Fragment and the Indochina Block.

  20. Assessment of different bedding systems for lactating cows in freestall housing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to compare different bedding systems for lactating cows in freestall housing. Bedding systems included new sand (NS), recycled byproducts of manure separation (organic solids [OS] and recycled sand [RS]), and foam-core mattresses with a shallow layer of OS (MS). The e...

  1. China Dust and Sand

    Atmospheric Science Data Center

    2013-04-16

    article title:  Dust and Sand Sweep Over Northeast China     ... (MISR) captured these views of the dust and sand that swept over northeast China on March 10, 2004. Information on the ... available at JPL March 10, 2004 - Dust and sand sweep the northeast region. project:  MISR ...

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

    PubMed

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

    2013-01-01

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

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

    USGS Publications Warehouse

    Nordin, Carl F.; Perez-Hernandez, David

    1989-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Benaafi, Mohammed; Abdullatif, Osman

    2014-05-01

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

  5. On one mechanism forming linear sand banks

    NASA Astrophysics Data System (ADS)

    Huthnance, John M.

    1982-01-01

    Asymmetric tidal currents ( Huthnance, 1973) provide a fluid-dynamical basis for Caston's (1972) description of linear sand-bank maintenance by converging sand transport. We suppose (i) depth-uniform tidal currents, slightly inclined to the bank crest, (ii) bottom-drag, which retards the current more over the bank and (iii) a faster-than-linear increase of sand transport with current. Then over a sloping bank side the total tidal current having an upslope component and the associated onto-bank sand transport are stronger than the retarded reverse tidal current and transport coming off the bank. Supposing that (iv) sand is more easily transported 'downhill' shortwavelength perturbations on a level sea floor are suppressed. There is a maximum bed-form growth rate at a particular wavelength (typically 250 times the water depth) and orientation (relative to the tidal currents) which probably evolve and persist during subsequent sand-bank growth. The orientation is sensitive to the (uncertain) formulation of supposition (iv), and is probably also susceptible to (for example) the trend of an adjacent coastline. In the representative context of friction-dominated tidal currents, the banks evolve to an equilibrium profile which is flatter on top than a sinusoid owing to wind-wave erosion and the inclination to the tidal current. For a limited sand supply the banks narrow to about one-fifth of their separation; further restriction mainly reduces their height. A net sand-transport overall due to a stronger ebb tide (say) than flood, as occurs over the Norfolk Sandbanks, yields the observed steeper slope on the obliquely downstream side of the bank (as viewed by the stronger ebb current).

  6. On Motion of Biofuel Particles in a Fluidized Bed

    NASA Astrophysics Data System (ADS)

    Buchilko, É. K.; Greben‧kov, A. Zh.; Borodulya, V. A.; Pitsukha, E. A.; Teplitskii, Yu. S.

    2016-11-01

    The migration of macroparticles in a fluidized bed of a finely divided quartz sand has been studied experimentally. The mechanism underlying the influence of the mixing of fluidized bed particles on the character of macroparticle motion is described. The dependence of the depth of macroparticle immersion on the physical and operational parameters has been obtained.

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

    SciTech Connect

    Olson, H.C.

    1986-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Turner, Brian R.; Smith, Denys B.

    1997-12-01

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

  9. Sand wave fields beneath the Loop Current, Gulf of Mexico: Reworking of fan sands

    USGS Publications Warehouse

    Kenyon, Neil H.; Akhmetzhanov, A.M.; Twichell, D.C.

    2002-01-01

    Extensive fields of large barchan-like sand waves and longitudinal sand ribbons have been mapped by deep-towed SeaMARC IA sidescan sonar on part of the middle and lower Mississippi Fan that lies in about 3200 m of water. The area is beneath the strongly flowing Loop Current. The bedforms have not been adequately sampled but probably consist of winnowed siliciclastic-foraminiferal sands. The size (about 200 m from wingtip to wingtip) and shape of the large barchans is consistent with a previously observed peak current speed of 30 cm/s, measured 25 m above the seabed. The types of small-scale bedforms and the scoured surfaces of chemical crusts, seen on nearby bottom photographs, indicate that near-bed currents in excess of 30 cm/s may sometimes occur. At the time of the survey the sand transport direction was to the northwest, in the opposite direction to the Loop Current but consistent with there being a deep boundary current along the foot of the Florida Escarpment. Some reworking of the underlying sandy turbidites and debris flow deposits is apparent on the sidescan sonar records. Reworking by deep-sea currents, resulting in erosion and in deposits characterised by coarsening upwards structures and cross-bedding, is a process that has been proposed for sand found in cores in shallower parts of the Gulf of Mexico. This process is more widespread than hitherto supposed. ?? 2002 Published by Elsevier Science B.V.

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

    NASA Astrophysics Data System (ADS)

    Cui, Y.

    2006-12-01

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

  11. 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)

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

    1999-12-01

    The Palaeoproterozoic positive excursion of δ 13Ccarb is now considered as three positive shifts of δ 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, δ 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 δ 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 Δc 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 δ 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 δ 13Ccarb and δ 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

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

    PubMed

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

    2013-02-19

    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.

  13. Large sand waves in Navarinsky Canyon head, Bering Sea

    USGS Publications Warehouse

    Karl, Herman A.; Carlson, P.R.

    1982-01-01

    Sand waves are present in the heads of large submarine canyons in the northwestern Bering Sea. They vary in height between 2 to 15 m and have wavelengths of 600 m. They are not only expressed on the seafloor, but are also well defined in the subsurface and resemble enormous climbing bed forms. We conjecture that the sand waves originated during lower stands of sea level in the Pleistocene. Although we cannot explain the mechanics of formation of the sand waves, internal-wave generated currents are among four types of current that could account for these large structures. ?? 1982 A. M. Dowden, Inc.

  14. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2006-01-01

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

  15. Numerical modeling of wind-blown sand on Mars.

    PubMed

    Huang, HaoJie; Bo, TianLi; Zheng, XiaoJing

    2014-09-01

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

  16. Aeolian Sand Transport with Collisional Suspension

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Aeolian transport is an important mechanism for the transport of sand on Earth and on Mars. Dust and sand storms are common occurrences on Mars and windblown sand is responsible for many of the observed surface features, such as dune fields. A better understanding of Aeolian transport could also lead to improvements in pneumatic conveying of materials to be mined for life support on the surface of the Moon and Mars. The usual view of aeolian sand transport is that for mild winds, saltation is the dominant mechanism, with particles in the bed being dislodged by the impact of other saltating particles, but without in-flight collisions. As the wind becomes stronger, turbulent suspension keeps the particles in the air, allowing much longer trajectories, with the corresponding increase in transport rate. We show here that an important regime exists between these two extremes: for strong winds, but before turbulent suspension becomes dominant, there is a regime in which in-flight collisions dominate over turbulence as a suspension mechanism, yielding transport rates much higher than those for saltation. The theory presented is based on granular kinetic theory, and includes both turbulent suspension and particle-particle collisions. The wind strengths for which the calculated transport rates are relevant are beyond the published strengths of current wind tunnel experiments, so these theoretical results are an invitation to do experiments in the strong-wind regime. In order to make a connection between the regime of saltation and the regime of collisional suspension, it is necessary to better understand the interaction between the bed and the particles that collide with it. This interaction depends on the agitation of the particles of the bed. In mild winds, collisions with the bed are relatively infrequent and the local disturbance associated with a collision can relax before the next nearby collision. However, as the wind speed increases, collision become more frequent

  17. Water resources of Red River Parish, Louisiana

    USGS Publications Warehouse

    Newcome, Roy; Page, Leland Vernon

    1963-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  19. Have the northwest Negev dunefield sands reddened since their deposition?

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Sand grain coating redness has been extensively both in coastal and inland desert dunes. In Israel, sand redness has been quantified by calculating a spectral redness index (RI) using single RGB bands (RI= R2/(B*G3)) from reflectance spectroscopy. The RI values have been correlated to ferric oxide mass that was dissolved from sand grain coatings (Ben Dor et al., 2006; Tsoar et al., 2008). Five main requirements have been proposed to enhance sand grain reddening: iron source from the weathering of iron-bearing minerals originating from parent rock or aeolian dust, minimum moisture content, oxidizing interstitial conditions, sediment stability and time. Thus, as many researches have suggested, when the source factors and climatic conditions are homogenous, redder sands indicate increased maturity. The northwest Negev dunefield has been classified by Tsoar et al. (2008) into 3 incursion units based upon contouring a grid of RI values for surface sand samples. The central incursion unit has been suggested to be younger due to relatively lower RI values that decrease to the east. This work tests the relationship between RI values and optically stimulated luminescence (OSL) ages of aeolian sand sampled from the near surface down to dune substrate throughout the NW Negev dunefield. Room-dried sand samples were measured in the laboratory with an ASD FieldSpec spectrometer and RI was calculated. Dune sections have been found to usually have similar RI values throughout their vertical profile despite OSL ages ranging between recent and Late Pleistocene. Along a W-E transect, RI values also tend to be similar. The central (Haluzza) part of the dunefield exhibits significantly lower RI values than RI of sands south of the Qeren Ridge. Dune base OSL ages possibly representing burial/stabilization of an initial incursion are slightly more mature in the south and may be evidence of the earliest dune incursion into the Negev. Thus the increased redness may be attributed to an

  20. Optical and radiocarbon ages of stacked paleosols and dune sands in the Nebraska Sand Hills, USA

    NASA Astrophysics Data System (ADS)

    Goble, R. J.; Mason, Joseph A.; Loope, David B.; Swinehart, James B.

    2004-05-01

    Optical ages for eolian sands from the Nebraska Sand Hills indicate periods of extensive eolian activity at ca 115±25, 840±70, 2300±240, and 3560±340 a. Activity was also noted at single sampling locations at ca 6180±370, 8430±510 and 13110±800 a. Many of these ages are similar to those noted by earlier authors. Optical ages from samples collected within paleosols indicate shorter and possibly less extensive periods of eolian activity at approximately 1220±150, 1590±110, and possibly 1950±150 a, during which the paleosol sands accumulated. What was originally interpreted as a single 1.2 m thick paleosol is shown by optical dating to consist of three or more welded soils developed within eolian sands with optical ages of ca 3800±240, 2740±240, 1560±110, and possibly 1930±140 a, each of which match eolian pulses recognized elsewhere. Scatter in some optical ages is attributable to intersection of sand-filled rodent burrows extending in outcrop 1.5 m below the contact between paleosol and overlying topset beds. A 5310±360 a optical age for one probable intersected burrow provides evidence for upward or lateral transport of older sands.

  1. Steam sand dryer in northeast part of sand tower. View ...

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

    Steam sand dryer in northeast part of sand tower. View to northeast - Duluth & Iron Range Rail Road Company Shops, Sand Tower, Southwest of downtown Two Harbors, northwest of Agate Bay, Two Harbors, Lake County, MN

  2. An Affair with Sand.

    ERIC Educational Resources Information Center

    Stroud, Sharon

    1980-01-01

    Described is a resource idea developed for the teaching of oceanography to junior high students. Sand is studied to help make the study of beaches more relevant to students who may have never seen an ocean. Sand samples are brought into the classroom from various coastal cities, then analyzed and compared. (Author/DS)

  3. Sand dunes on the central Delmarva Peninsula, Maryland and Delaware

    USGS Publications Warehouse

    Denny, Charles Storrow; Owens, James Patrick

    1979-01-01

    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.

  4. Prediction of sand transport over immobile gravel from supply limited to capacity conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prediction of the transport of sand in channels armored with gravel downstream of dams is difficult but necessary for the range of bed conditions from supply limited to capacity transport. Previous work has shown that information on the mean elevation of the sand relative to the gravel and on the s...

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

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Borges, J. B.

    2003-12-01

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

  7. 1. View looking east from sand bar on west side ...

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

    1. View looking east from sand bar on west side of bridge, upstream in the bed of Sugar Creek. West elevation of the bridge - Vigo County Bridge No. 139, Spanning Sugar Creek at Seventy-fourth Place, Terre Haute, Vigo County, IN

  8. Field assessment of alternative bed-load transport estimators

    USGS Publications Warehouse

    Gaeuman, G.; Jacobson, R.B.

    2007-01-01

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

  9. Crest line minimal model for sand dune

    NASA Astrophysics Data System (ADS)

    Guignier, Lucie; Valance, Alexandre; Lague, Dimitri

    2013-04-01

    In desert, complex patterns of dunes form. Under unidirectional wind, transverse rectilinear dunes or crescent shaped dunes called barchan dunes can appear, depending on the amount of sediment available. Most rectilinear transverse sand dunes are observed to fragment, for example at White Sands (New Mexico, United States of America) or Walvis Bay (Namibia). We develop a reduced complexity model to investigate the morphodynamics of sand dunes migrating over a non-erodible bed under unidirectional wind. The model is simply based on two physical ingredients, namely, the sand capture process at the slip face and the cross-wind sand transport. The efficiency of the sand capture process is taken to be dependent of the dune height and lateral diffusion is considered on both the windward and lee sides of the dune. In addition, the dune cross section is assumed to be scale invariant and is approximated by a triangular shape. In this framework, the dune dynamics is reduced to the motion of a string representing the dune crest line and is expressed as a set of two coupled nonlinear differential equations. This simple model reveals its ability to reproduce basic features of barchan and transverse dunes. Analytical predictions are drawn concerning dune equilibrium shape, stability and long-term dynamics. We derive, in particular, analytical solutions for barchan dunes, yielding explicit relationships between their shape and the lateral sand diffusion; and analytical predictions for the migration speed and equilibrium sand flux. A stability analysis of a rectilinear transverse dune allows us to predict analytically the wavelength emerging from fluctuations of the dune crest. We also determine the characteristic time needed for the rectilinear dune to fragment into a multitude of barchan dunes. These outcomes show that extremely simple ingredients can generate complex patterns for migrating dunes. From several dune field data, we are able to determine values of the model

  10. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2010-01-01

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

  11. Drying of solids in fluidized beds

    SciTech Connect

    Kannan, C.S.; Thomas, P.P.; Varma, Y.B.G.

    1995-09-01

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

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

    PubMed

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

    2012-11-01

    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*.

  13. The Flow of Sand.

    ERIC Educational Resources Information Center

    Yersel, Metin

    2000-01-01

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

  14. Sand consolidation methods

    SciTech Connect

    Friedman, R.H.

    1984-01-24

    Methods are provided for selectively consolidating sand grains within a subterranean formation. First an acidic salt catalyst such as ZnCl/sub 2/ is injected into the subterranean formation, wherein the acidic salt catalyst is adsorbed to the surface of the sand grains. Next a polymerizable resin composition such as furfuryl alcohol oligomer is introduced into the well formation. Polymerization of the resin occurs upon exposure to the elevated well temperatures and contact with the acid salt catalyst adsorbed to the sand grains. The polymerized resin serves to consolidate the surfaces of the sand grains while retaining permeability through the pore spaces. An ester of a weak organic acid is included with the resin compositions to control the extent of a polymerization by consuming the water by-product formed druing the polymerization reaction.

  15. Washington Gas makes switch to recycled concrete bedding

    SciTech Connect

    Gunther, K.M. . Materials Testing Lab.)

    1993-08-01

    Washington Gas Light Co., following extensive testing, is successfully using recycled concrete as bedding with plastic pipe that has produced cost savings and environmental benefits. The search for new bedding material for use with plastic pipe started in the mid-1970's, when the traditionally used sand was becoming increasingly more difficult to purchase at any price. Sand bedding has been used with plastic services and mains because it provided maximum scratch and rock impingement protection. Although it added to installation cost, sand was accepted as a necessary expense. Decision to use recycled concrete followed studies conducted in 1990. It was discovered that polyethylene was not severely scratched by the concrete or even some of the materials that were rejected during testing in 1976. Toughness improvements in modern polyethylenes explains the difference in the results and proved safe for use with virtually any commercial backfill material.

  16. Sand Volcano Following Earthquake

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Sand boil or sand volcano measuring 2 m (6.6 ft.) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction) in the October 17, 1989, Loma Prieta earthquake. Vented sand contains marine-shell fragments. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: J.C. Tinsley, U.S. Geological Survey)

  17. Geologic and paleoecologic studies of the Nebraska Sand Hills

    USGS Publications Warehouse

    Ahlbrandt, Thomas S.; Fryberger, S.G.; Hanley, John H.; Bradbury, J. Platt

    1980-01-01

    PART A: The Nebraska Sand Hills are an inactive, late Quaternary, most probably Holocene, dune field (covering 57,000 km 2 ) that have been eroded along streams and in blowouts, resulting in excellent lateral and vertical exposures of the stratification of dune and interdune sediments. This paper presents new data on the geometry, primary sedimentary structures, modification of sedimentary structures, direction of sand movement, and petrography of these eolian deposits. Eolian deposits of the Sand Hills occur as relatively thin (9-24 m) 'blanket' sands, composed of a complex of dune and discontinuous, diachronous interdune deposits unconformably overlying fluviolacustrine sediments. The internal stratification of large dunes in the Sand Hills (as high as 100 m), is similar to the internal stratification of smaller dunes of the same type in the Sand Hills, differing only in scale. Studies of laminae orientation in the Sand Hills indicate that transverse, barchan, and blowout dunes can be differentiated in rocks of eolian origin using both the mean dip angle of laminae and the mean angular deviation of dip direction. A variety of secondary structures modify or replace primary eolian stratification in the Sand Hills, the more common of which are dissipation structures and bioturbation. Dissipation structures in the Sand Hills may develop when infiltrating water deposits clay adjacent to less permeable layers in the sand, or along the upper margins of frozen layers that form in the sands during winter. Cross-bed measurements from dunes of the Nebraska Sand Hills necessitate a new interpretation of the past sand transport directions. The data from these measurements indicate a general northwest-to-southeast drift of sand, with a more southerly drift in the southeast part of the Sand Hills. A large area of small dunes < 100 m high) described by Smith (1965) as linear or seif in the central part of the Sand Hills was interpreted by him on the basis of morphology only. We

  18. Packed Bed Reactor Experiment

    NASA Video Gallery

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

  19. Biological denitrification in a fluidized bed.

    PubMed

    Narjari, N K; Khilar, K C; Mahajan, S P

    1984-12-01

    A fluidized bed biofilm reactor using sand as the carrier particle was employed to study the effects of superficial velocity on the removal of nitrates as well as on the growth of the biofilm. Velocity was found to affect significantly both nitrate removal and biofilm growth. An analysis based on heterogenous catalysis was used to describe the denitrification process. There is good agreement between analysis and experimental measurements for startup and steady-state operating conditions.

  20. Slow sand filtration of secondary clarifier effluent for wastewater reuse.

    PubMed

    Langenbach, K; Kuschk, P; Horn, H; Kästner, M

    2009-08-01

    Appropriate technologies are needed for disinfection of wastewater to allow safe reuse. Slow sand filtration is a simple technology used for pathogen and particle removal in drinking water purification. We investigated removal of fecal indicator bacteria relevant for wastewater reuse, particle removal, and runtime in slow sand filtration of secondary clarifier effluent. The key process parameters hydraulic loading rate, sand grain size distribution, and filter bed depth were systematically varied. Slow sand filters for tertiary treatment of wastewater seem promising for wastewater reuse, especially in arid developing countries. They eliminated 1.9-2.6 log10-units of E. coli and 1.9-3.0 log10-units of intestinal Enterococci reaching effluent concentrations of 11-142 CFU per 100 mL of E. coli and 2-24 CFU per 100 mL of intestinal Enterococci. Bacteria removal was shown to be a function of sand surface area, dirt layer, and supernatant water. Sand surface area per filter surface area should not be chosen below 2000 m2/m2. Slow sand filters removed 70-84% of total suspended solids reaching effluent concentrations of 1.2-2.3 mg/L and turbidity levels of 0.5-0.8 NTU. Average runtime was between 59 and 148 days.

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

    USGS Publications Warehouse

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

    2005-01-01

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

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

    USGS Publications Warehouse

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

    2008-01-01

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

  3. Kentucky tar sand project

    SciTech Connect

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

    1985-03-01

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

  4. Giant sand waves at the mouth of San Francisco Bay

    USGS Publications Warehouse

    Barnard, P.L.; Hanes, D.M.; Rubin, D.M.; Kvitek, R.G.

    2006-01-01

    A field of giant sand waves, among the largest in the world, recently was mapped in high resolution for the first time during a multibeam survey in 2004 and 2005 through the strait of the Golden Gate at the mouth of San Francisco Bay in California (Figure la). This massive bed form field covers an area of approximately four square kilometers in water depths ranging from 30 to 106 meters, featuring more than 40 distinct sand waves with crests aligned approximately perpendicular to the dominant tidally generated cross-shore currents, with wavelengths and heights that measure up to 220 meters and 10 meters, respectively. Sand wave crests can be traced continuously for up to two kilometers across the mouth of this energetic tidal inlet, where depth-averaged tidal currents through the strait below the Golden Gate Bridge exceed 2.5 meters per second during peak ebb flows. Repeated surveys demonstrated that the sand waves are active and dynamic features that move in response to tidally generated currents. The complex temporal and spatial variations in wave and tidal current interactions in this region result in an astoundingly diverse array of bed form morphologies, scales, and orientations. Bed forms of approximately half the scale of those reported in this article previously were mapped inside San Francisco Bay during a multibeam survey in 1997 [Chin et al., 1997].

  5. Bed Stability and Debris Flow Erosion: A Dynamic "Shields Criterion" Associated with Bed Structure

    NASA Astrophysics Data System (ADS)

    Longjas, A.; Hill, K. M.

    2015-12-01

    Debris flows are mass movements that play an important role in transporting sediment from steep uplands to rivers at lower slopes. As the debris flow moves downstream, it entrains materials such as loose boulders, gravel, sand and mud deposited locally by shorter flows such as slides and rockfalls. To capture the conditions under which debris flows entrain bed sediment, some models use something akin to the Shields' criterion and an excess shear stress of the flow. However, these models typically neglect granular-scale effects in the bed which can modify the conditions under which a debris flow is erosional or depositional. For example, it is well known that repeated shearing causes denser packing in loose dry soils, which undoubtedly changes their resistance to shear. Here, we present laboratory flume experiments showing that the conditions for entrainment by debris flows is significantly dependent on the aging of an erodible bed even for narrowly distributed spherical particles. We investigate this quantitatively using particle tracking measurements to quantify instantaneous erosion rates and the evolving bed structure or "fabric". With progressive experiments we find a signature that emerges in the bed fabric that is correlated with an increasing apparent "fragility" of the bed. Specifically, a system that is originally depositional may become erosional after repeated debris flow events, and an erodible bed becomes increasingly erodible with repeated flows. We hypothesize that related effects of bed aging at the field scale may be partly responsible for the increasing destructiveness of secondary flows of landslides and debris flows.

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

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

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

  7. Ganges Chasma Sand Sheet

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

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

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

    Image information: VIS instrument. Latitude -6.4, Longitude 310.7 East (49.3 West). 19 meter/pixel resolution.

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

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

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

    SciTech Connect

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

    1993-11-01

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

  9. Sand Dunes with Frost

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

  10. Incident angle of saltating particles in wind-blown sand.

    PubMed

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

    2013-01-01

    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.

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

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

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

  12. Loading and Unloading Finishing Pigs: Effects of Bedding Types, Ramp Angle, and Bedding Moisture

    PubMed Central

    Garcia, Arlene; McGlone, John J.

    2014-01-01

    Simple Summary Current guidelines suggest the use of ramps below 20 degrees to load and unload pigs; however, they do not suggest the use of any specific bedding. Bedding types (nothing, feed, sand, wood shavings, and hay) were tested with finishing pigs (70–120 kg) to determine which was most effective in reducing slips, falls, and vocalizations at three ramp angles, two moisture levels, over two seasons. Slips, falls, and vocalizations were summed to establish a scoring system for the types of beddings. Heart rate and the total time it took to load and unload pigs, increased as the slope increased. Bedding, bedding moisture, season, and ramp slope interacted to impact the total time it took for finishing pigs to load and unload the ramp. Selection of the best bedding depends on ramp slope, season, and wetness of bedding. Abstract The use of non-slip surfaces during loading and unloading of finishing pigs plays an important role in animal welfare and economics of the pork industry. Currently, the guidelines available only suggest the use of ramps with a slope below 20 degrees to load and unload pigs. However, the total time it takes to load and unload animals and slips, falls, and vocalizations are a welfare concern. Three ramp angles (0, 10 or 20 degrees), five bedding materials (nothing, sand, feed, wood shavings or wheat straw hay), two moistures (dry or wet bedding, >50% moisture) over two seasons (>23.9 °C summer, <23.9 °C winter) were assessed for slips/falls/vocalizations (n = 2400 pig observations) and analyzed with a scoring system. The use of bedding during summer or winter played a role in the total time it took to load and unload the ramp (p < 0.05). Bedding, bedding moisture, season, and slope significantly interacted to impact the total time to load and unload finishing pigs (p < 0.05). Heart rate and the total time it took to load and unload the ramp increased as the slope of the ramp increased (p < 0.05). Heart rates were higher during the

  13. Barnacle-dominated limestone with giant cross-beds in a non-tropical, tide-swept, Pliocene forearc seaway, Hawke's Bay, New Zealand

    NASA Astrophysics Data System (ADS)

    Kamp, Peter J. J.; Harmsen, Fraka J.; Nelson, Campbell S.; Boyle, Susan F.

    1988-11-01

    Pliocene, non-tropical, widespread and locally thick (up to 100 m) limestones occur in Hawke's Bay, eastern North Island, where they are intimately associated with very thick ( > 5 km), terrigenous-dominated, Neogene sequences that formed in a tectonically active convergent margin setting. The non-tropical character of the limestones is shown unequivocally by (1) the complete dominance of skeletal calcarenites and calcirudites, (2) the occurrence of oyster banks as the only in situ organic structures, (3) the dominance of barnacles, epifaunal molluscs, bryozoans, echinoderms, foraminifers, brachiopods and calcareous red algae as skeletal components, and (4) the preponderance of calcite over aragonite in the mineralogy of the skeletal grains and cements. The abundance of barnacle fragments in the limestones, and the related exclusive occurrence of only one major organic association, a barnacle-(epifaunal) bivalve-bryozoan assemblage, is striking and unusual given the extent of the limestones. Pecten and oyster valves acted as substrates for barnacle attachment, and their growth was promoted by strong tidal paleocurrents that swept the depositional setting: a long (450 km), narrow (30-50 km) forearc basin seaway, which formed between an actively deforming subduction complex to the east and an uplifting structural ridge to the west. Synsedimentary deformation promoted limestone formation on the margins of the seaway by creating current-swept, clastic-free submarine ridges that acted as the sites of carbonate production. Tidal flows dispersed the carbonate constituents and organised them into a wide spectrum of tide-influenced, cross-bedded and horizontal structures. Most spectacular are occurrences of giant tabular cross-beds, with sets 10-40 m thick and foreset dips of 7-36°, some interpreted as the deposits of major sand bars on carbonate deltas marginal to the mouths of saddles traversing the rising antiforms, and others analogous to modern linear sand ridges. The

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

    USGS Publications Warehouse

    Grams, Paul E.

    2013-01-01

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

  15. Speleothems and Sand Castles

    ERIC Educational Resources Information Center

    Hance, Trevor; Befus, Kevin

    2015-01-01

    The idea of building sand castles evokes images of lazy summer days at the beach, listening to waves crash, enjoying salty breezes, and just unplugging for a while to let our inner child explore the wonderful natural toys beneath our feet. The idea of exploring caves might evoke feelings and images of claustrophobia or pioneers and Native…

  16. Building with Sand

    ERIC Educational Resources Information Center

    Ashbrook, Peggy

    2010-01-01

    Children playing in damp sand invariably try to make a tower or a tunnel. By providing experiences with a variety of materials, alone and together, teachers set up the conditions for children to learn through their senses and ensure that a class approaches a topic with a common set of experiences to build on. Learning about the properties of…

  17. The Engineering of Sand.

    ERIC Educational Resources Information Center

    Pilkey, Orrin H.

    1989-01-01

    Discussed are beach replenishment, and hard structures in relation to the sand transportation system. Failures of current engineering practices and the resulting costs to the taxpayer are stressed. Equations and parameters used to make predictions of beach durability are criticized. (CW)

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

    SciTech Connect

    Miciotto, S.A.

    1980-01-01

    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.

  19. Extracting Oil From Tar Sands

    NASA Technical Reports Server (NTRS)

    Ford, L. B.; Daly, D.

    1984-01-01

    Recovery of oil from tar sands possible by batch process, using steam produced by solar heater. In extraction process, solar heater provides steam for heating solvent boiler. Boiling solvent removes oil from tar sands in Soxhlet extractor.

  20. Northern Sand Sea

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

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

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

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

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

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

  1. Reefs, sand and reef-like sand: A comparison of the benthic biodiversity of habitats in the Dutch Borkum Reef Grounds

    NASA Astrophysics Data System (ADS)

    Coolen, Joop W. P.; Bos, Oscar G.; Glorius, Sander; Lengkeek, Wouter; Cuperus, Joël; van der Weide, Babeth; Agüera, Antonio

    2015-09-01

    Reefs play an important role in the distribution of species associated with hard substrates and are of value for biodiversity conservation. High densities of the habitat building annelid Lanice conchilega also increase local biodiversity. This study describes the benthic biodiversity of a rocky reef and its surrounding sand bottom with dense L. conchilega beds in the Borkum Reef Grounds, north of the island of Schiermonnikoog in the Dutch North Sea. A side-scan sonar survey revealed distinct seabed areas with high acoustic reflections, indicating the presence of hard substrate on the sandy seafloor. To ground truth the side-scan sonar data and make an inventory of the biodiversity of the observed habitats, a multi-method sampling approach (box corer, SCUBA airlift sampler and visual transects, drop-down camera) was used. This revealed (1) rocky reefs: a combination of gravel, stones and rocks; (2) individual rocks in a sandy environment; (3) sand with dense L. conchilega beds (> 1500 ind·m- 2) and (4) sand bottom habitat. A total of 193 taxa were found with many unique species per habitat. Species richness was significantly higher on sand when compared to the rocky reef (NB-GLM; p = 0.006), caused by the presence of dense L. conchilega beds (Poisson GLM; p < 0.001). Including dense L. conchilega beds as an additional habitat showed that these held a higher species richness than the rocky reefs (NB-GLM; p = 0.002), while sand without dense L. conchilega beds did not (NB-GLM; p = 0.14). Since the rocky reefs were present on a sandy bottom, the local biodiversity more than doubled with the presence of rocky reefs. The nMDS plot clearly separated the sand and rocky reef communities and also showed a clustering of dense L. conchilega beds within the sand samples. Each method detected unique species, demonstrating the value of a multi-method approach compared to e.g. box coring alone. This study identified several species previously unknown to the Borkum Reefs Grounds

  2. Evaluation of fluid bed heat exchanger optimization parameters. Final report

    SciTech Connect

    Not Available

    1980-03-01

    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.

  3. In situ measurements of advective solute transport in permeable shelf sands

    NASA Astrophysics Data System (ADS)

    Reimers, Clare E.; Stecher, Hilmar A.; Taghon, Gary L.; Fuller, Charlotte M.; Huettel, Markus; Rusch, Antje; Ryckelynck, Natacha; Wild, Christian

    2004-01-01

    Solute transport rates within the uppermost 2 cm of a rippled continental shelf sand deposit, with a mean grain size of 400-500 μm and permeabilities of 2.0-2.4×10 -11 m 2, have been measured in situ by detecting the breakthrough of a pulse of iodide after its injection into the bottom water. These tracer experiments were conducted on the USA Middle Atlantic Bight shelf at a water depth of ˜13 m using a small tethered tripod that carried a close-up video camera, acoustic current meter, motorized 1.5 liter "syringe", and a microprofiling system for positioning and operating a solid-state voltammetric microelectrode. When triggered on shipboard, the syringe delivered a 0.21 M solution of potassium iodide and red dye through five nozzles positioned around and above the buried tip of the voltammetric sensor for 0.65-5 min. Bottom turbulence rapidly mixed and dispersed the tracer, which then was carried into the bed by interfacial water flows associated with ripple topography. The advective downward transport to the sensor tip was timed by a sequence of repetitive voltammetric scans. The distance-averaged vertical velocity, expressed as the depth of the sensor tip in the sand divided by the time to iodide breakthrough, was found to vary from 6 to 53 cm h -1 and generally to decrease with sediment depth. Because of episodic pumping and dispersion associated with the greatest 5% of wave heights and current speeds recorded, some concentration vs. time responses showed evidence of uneven solute migration. For reasons of mass balance, the advective flow field in the surface layers of permeable beds includes regions of water intrusion, horizontal pore-water flow and upwelling which also may explain some of the observed uneven migration. Pore-water advection was also evident in oxygen profiles measured before and after tracer injection with the voltammetric sensor. These profiles showed irregular distributions and oxygen penetration depths of 4-4.5 cm. Sand cores from the

  4. Control of Phlebotomine Sand Flies in Iran: A Review Article

    PubMed Central

    2016-01-01

    Leishmaniasis has long been known as a significant public health challenge in many parts of Iran. Phlebotomus papatasi and P. sergenti are the vectors of Zoonotic Cutaneous Leishmaniasis and Anthroponotic Cutaneous Leishmaniasis respectively, and 5 species of sand flies including P. kandelakii, P. neglectus, P. perfiliewi, P. keshishiani and P. alexandri are considered as probable vectors of Zoonotic visceral leishmaniasis. A literature search was performed of the relevant multiple databases from 1966 to 2013 to include studies on sand flies, vector control, leishmaniasis, Phlebotomus. Sand fly control in Iran began in 1966 by Iranian researchers, and long-term evaluation of its effects was completed in the study areas of the country. Herein, a review of vector control strategies in Iran to combat leishmaniasis including indoor residual spraying, application of chemicals in rodent burrows, impregnation of bed nets and curtains with insecticides, the use of insect repellents, impregnation of dog collars and the susceptibility of sand fly vectors to various insecticides has been summarized thus far. The investigation of the behavioral patterns of the adults of different sand fly species, introduction of biological insecticide agents, the use of insecticidal plants and other novel strategies for the control of sand fly populations have received much attention in the areas of studies, hence should be recommended and improved since they provide optimistic results. PMID:28032095

  5. Effect of Bedding Material on Performance, Health, and Hide Contamination of Calves Reared in Hutches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy calf hutches are often bedded with straw (STR), but sand (SND) and wood shavings (SHV) are becoming more common. This study compared 3 different beddings for growth and health of calves and microbial presence on their hides. Hutches were blocked by location and each of 3 hutches in a block w...

  6. Effect of Bedding Material on Flies, and Behavior and Innate Immunity of Calves Reared in Hutches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy calf hutches are often bedded with straw (STR), but sand (SND) and wood shavings (SHV) are becoming more common. The objective was to compare 3 beddings for presence of flies and measures of innate immunity and behavior of calves. Hutches were blocked by location and each of 3 hutches in a blo...

  7. Effect of Bedding Material on Flies, and Behavior and Innate Immunity of Calves Reared in Hutches.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy calf hutches are often bedded with straw (STR), but sand (SND) and wood shavings (SHV) are becoming more common. The objective was to compare 3 beddings for presence of flies and measures of innate immunity and behavior of calves. Hutches were blocked by location and each of 3 hutches in a blo...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  9. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  10. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  11. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  12. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  13. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  14. The Rheology of Acoustically Fluidized Sand

    NASA Astrophysics Data System (ADS)

    Conrad, J. W.; Melosh, J.

    2013-12-01

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

  15. High-energy carbonate-sand accumulation, the Quicksands, southwest Florida Keys

    USGS Publications Warehouse

    Shinn, Eugene A.; Lidz, Barbara H.; Holmes, Charles W.

    1990-01-01

    High-resolution seismic-reflection profiles of the Quicksands, located along a broad ridge on the platform shelf west of Key West, Florida, indicate a significant deposit of non-oolitic carbonate sand occurs in a belt 47 km long by 28 km wide. The surface of the belt is ornamented by large (5 m), migrating tidal bars, oriented in a north-south direction, on which sand waves, oriented in an east-west direction, are superimposed. Some of the sand waves are awash at low tide. The sand waves are formed by strong reversing tidal currents flowing between the Gulf of Mexico and the Straits of Florida. The waves migrate directly over Pleistocene bedrock to the east, but the deposit thickens to the west and sand waves there overlie non-oolitic Holocene accumulations as thick as 12 m. Westward-dipping accretionary bedding indicates that net migration of the sands is to the west, despite north-south movement of tidal currents. The westward edge of the accumulation has accreted over deeper, muddier deposits. Although tidal currents and resultant bedforms appear identical to those of active ooid deposits in the Bahamas and elsewhere, no oolitically coated grains were found in this study. Thin-section analyses show the principal component (average 48%) of the sands is fragmented plates of species of the green alga Halimeda , followed by particulate coral (average 17%), which increases off the flanks of the main sand body. Short vibracores confirm the presence of cross-bedding.

  16. Phase diagrams of dune shape and orientation depending on sand availability.

    PubMed

    Gao, Xin; Narteau, Clément; Rozier, Olivier; Courrech du Pont, Sylvain

    2015-09-30

    New evidence indicates that sand availability does not only control dune type but also the underlying dune growth mechanism and the subsequent dune orientation. Here we numerically investigate the development of bedforms in bidirectional wind regimes for two different conditions of sand availability: an erodible sand bed or a localized sand source on a non-erodible ground. These two conditions of sand availability are associated with two independent dune growth mechanisms and, for both of them, we present the complete phase diagrams of dune shape and orientation. On an erodible sand bed, linear dunes are observed over the entire parameter space. Then, the divergence angle and the transport ratio between the two winds control dune orientation and dynamics. For a localized sand source, different dune morphologies are observed depending on the wind regime. There are systematic transitions in dune shape from barchans to linear dunes extending away from the localized sand source, and vice-versa. These transitions are captured fairly by a new dimensionless parameter, which compares the ability of winds to build the dune topography in the two modes of dune orientation.

  17. Phase diagrams of dune shape and orientation depending on sand availability

    PubMed Central

    Gao, Xin; Narteau, Clément; Rozier, Olivier; du Pont, Sylvain Courrech

    2015-01-01

    New evidence indicates that sand availability does not only control dune type but also the underlying dune growth mechanism and the subsequent dune orientation. Here we numerically investigate the development of bedforms in bidirectional wind regimes for two different conditions of sand availability: an erodible sand bed or a localized sand source on a non-erodible ground. These two conditions of sand availability are associated with two independent dune growth mechanisms and, for both of them, we present the complete phase diagrams of dune shape and orientation. On an erodible sand bed, linear dunes are observed over the entire parameter space. Then, the divergence angle and the transport ratio between the two winds control dune orientation and dynamics. For a localized sand source, different dune morphologies are observed depending on the wind regime. There are systematic transitions in dune shape from barchans to linear dunes extending away from the localized sand source, and vice-versa. These transitions are captured fairly by a new dimensionless parameter, which compares the ability of winds to build the dune topography in the two modes of dune orientation. PMID:26419614

  18. PROCESSING OF MONAZITE SAND

    DOEpatents

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

    1957-12-01

    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.

  19. Hybrid fluidized bed combuster

    DOEpatents

    Kantesaria, Prabhudas P.; Matthews, Francis T.

    1982-01-01

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

  20. Eye redness

    MedlinePlus

    Bloodshot eyes; Red eyes; Scleral injection; Conjunctival injection ... There are many causes of a red eye or eyes. Some are medical emergencies. Others are a cause for concern, but not an emergency. Many are nothing to worry about. Eye ...

  1. Origin of hysteresis in bed form response to unsteady flows

    NASA Astrophysics Data System (ADS)

    Martin, Raleigh L.; Jerolmack, Douglas J.

    2013-03-01

    Field and laboratory studies indicate that changes in riverbed morphology often lag changes in water discharge. This lagged response produces hysteresis in the relationship between water discharge and bed form geometry. To understand these phenomena, we performed flume experiments to observe the response of a sand bed to step increases and decreases in water discharge. For an abrupt rise in discharge, we observed that bed forms grew rapidly by collision and merger of bed forms migrating with different celerities. Growth rate slowed as bed forms approached equilibrium with the higher discharge regime. After an abrupt discharge drop, bed form decay occurred through formation of smaller secondary bed forms, in equilibrium with the lower discharge, which cannibalized the original, relict features. We present a simple model framework to quantitatively predict time scales of bed form adjustment to flow changes, based on equilibrium bed form heights, lengths, and celerities at low and high flows. For rising discharge, the model assumes that all bed form collisions result in irreversible merger, due to a dispersion of initial celerities. For falling discharge, we derive a diffusion model for the decay of relict high-stage features. Our models predict the form and time scale of experimental bed form adjustments. Additional experiments applying slow and fast triangular flood waves show that bed form hysteresis occurs only when the time scale of flow change is faster than the modeled (and measured) bed form adjustment time. We show that our predicted adjustment time scales can also be used to predict the occurrence of bed form hysteresis in natural floods.

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

    SciTech Connect

    Vondra, L.F.; Burningham, J.S.

    1995-08-01

    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.

  3. Cross-shore sand transport by infragravity waves as a function of beach steepness

    NASA Astrophysics Data System (ADS)

    Bakker, A. T. M.; Brinkkemper, J. A.; Steen, F.; Tissier, M. F. S.; Ruessink, B. G.

    2016-10-01

    Two field data sets of near-bed velocity, pressure, and sediment concentration are analyzed to study the influence of infragravity waves on sand suspension and cross-shore transport. On the moderately sloping Sand Motor beach (≈1:35), the local ratio of infragravity wave height to sea-swell wave height is relatively small (HIG/HSW<0.4), and sand fluxes are related to the correlation of the infragravity-wave orbital motion with the sea-swell wave envelope, r0. When the largest sea-swell waves are present during negative infragravity velocities (bound wave, negative correlation r0), most sand is suspended here, and the infragravity sand flux qIG is offshore. When r0 is positive, the largest sea-swell waves are present during positive infragravity velocities (free wave), and qIG is onshore directed. For both cases, the infragravity contribution to the total sand flux is, however, relatively small (<20%). In the inner surf zone of the gently (≈1:80) sloping Ameland beach, the infragravity waves are relatively large (HIG/HSW>0.4), most sand is suspended during negative infragravity velocities, and qIG is offshore directed. The infragravity contribution to the total sand flux is considerably larger and reaches up to ≈60% during energetic conditions. On the whole, HIG/HSW is a good indicator for the infragravity-related sand suspension mechanism and the resulting infragravity sand transport direction and relative importance.

  4. Intricately Rippled Sand Deposits

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on the image for Intricately Rippled Sand Deposits (QTVR)

    NASA's Mars Exploration Rover Spirit welcomed the beginning of 2006 on Earth by taking this striking panorama of intricately rippled sand deposits in Gusev Crater on Mars. This is an approximate true-color rendering of the 'El Dorado' ripple field provided by Spirit over the New Year's holiday weekend. The view spans about 160 degrees in azimuth from left to right and consists of images acquired by Spirit's panoramic camera on Spirit's 708th and 710th Martian days, or sols, (Dec. 30, 2005 and Jan. 1, 2006). Spirit used the Pancam's 750-nanometer, 530-nanometer and 430-nanometer filters to capture the colors on Mars. Scientists have eliminated seams between individual frames in the sky portion of the mosaic to better simulate the vista a person standing on Mars would see. Spirit spent several days acquiring images, spectral data, and compositional and mineralogical information about these large sand deposits before continuing downhill toward 'Home Plate.'

  5. Red Sea

    Atmospheric Science Data Center

    2013-04-16

    article title:  The Red Sea     View Larger Image ... 2000. Located between the East African coast and the Saudi Arabian peninsula, the Red Sea got its name because the blooms of a type of ... 2000 - The Red Sea between the East Africa coast and Saudi Arabian peninsula. project:  MISR category:  ...

  6. Bed material agglomeration during fluidized bed combustion

    SciTech Connect

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

    1993-02-01

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

  7. Is promise of Alberta's tar sands nearing reality

    SciTech Connect

    Stauffer, T.

    1993-10-15

    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.

  8. Wave-induced ripple development in mixed clay-sand substrates

    NASA Astrophysics Data System (ADS)

    Wu, Xuxu; Parsons, Daniel; Baas, Jaco H.; Mouazé, Dominique; McLelland, Stuart; Amoudry, Laurent; Eggenhuisen, Jorris; Cartigny, Matthieu; Ruessink, Gerben

    2016-04-01

    This paper reports on a series of experiments that aim to provide a fuller understanding of ripple development within clay-sand mixture substrates under oscillatory flow conditions. The work was conducted in the Total Environment Simulator at the University of Hull and constituted 6 separate runs, in which 5 runs were conducted under identical sets of regular waves (an additional run was conducted under irregular waves, but is not discussed in present paper). The bed content was systematically varied in its composition ranging from a pure sand bed through to a bed comprising 7.4% clay. A series of state-of-the-art measurements were employed to quantify interactions of near-bed hydrodynamics, sediment transport, and turbulence over rippled beds formed by wave action, during and after, each run. The experimental results demonstrate the significant influence of the amount of cohesive clay materials in the substrate on ripple evolution under waves. Most importantly, addition of clay in the bed dramatically slowed down the rate of ripple development and evolution. The equilibrium time of each run increased exponentially from 30 minutes under the control conditions of a pure sand bed, rising to ~350 minutes for the bed with the highest fraction of clay. The paper discusses the slower ripple growth rates with higher cohesive fractions, via an influence on critical shear, but highlights that the end equilibrium size of ripples is found to be independent of increasing substrate clay fraction. The suspended particles mass (SPM) concentration indicates that clay particles were suspended and winnowed by wave action. Additionally, laser granulometry of the final substrates verified that ripple crests were composed of pure sand layers that were absent at ripple troughs, reflecting a relatively higher winnowing efficiency at wave ripples crest. The winnowing process and its efficiency is inexorably linked to wave ripple development and evolution. The implications of the results

  9. Booming Sand Dunes

    NASA Astrophysics Data System (ADS)

    Vriend, Nathalie

    "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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

  11. Bed Bugs and Schools

    EPA Pesticide Factsheets

    Bed bugs have long been a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. They are successful hitchhikers, and can move from an infested site to furniture, bedding, baggage, boxes, and clothing.

  12. Bed rest during pregnancy

    MedlinePlus

    ... on the inferior vena cava. How Can I Deal with Discomfort from Bed Rest? Bed rest can ... Group Health Cooperative, Bellevue, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the ...

  13. Size distribution of Amazon River bed sediment

    USGS Publications Warehouse

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

    1980-01-01

    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.

  14. Space Radar Image of Namibia Sand Dunes

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  15. Introduction to Bed Bugs

    EPA Pesticide Factsheets

    The common bed bug (Cimex lectularius) is a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. EPA and other agencies all consider bed bugs a public health pest, but bed bugs are not known to transmit disease.

  16. Making a Bed

    ERIC Educational Resources Information Center

    Wexler, Anthony; Stein, Sherman

    2005-01-01

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

  17. Rhythmic bedding in prodeltaic deposits of the ancient Colorado River: Exploring genetic processes

    NASA Astrophysics Data System (ADS)

    Waresak, Sandra; Nalin, Ronald; Lucarelli, Andrea

    2016-04-01

    Prodeltaic deposits represent a valuable archive for the characterization of deltaic depositional systems, offering a distal, minimally reworked record of dominant processes active at the fluvial-marine interface. The Fish Creek Basin (CA, US) preserves a ~ 3-km thick, lower Pliocene, progradational deltaic succession formed when the ancestral Colorado River infiltrated a marine rift basin (the early Gulf of California). The unit in this succession interpreted as prodeltaic, corresponding to the upper Mud Hills Member of the Deguynos Formation, consists of ~ 300 m of muddy siltstones. A striking attribute of parts of this unit is the presence of rhythmic bedding, with consistently alternating silt- to fine sand-dominated and clay-dominated beds forming couplets with an average thickness of 12 cm. By performing a detailed sedimentological analysis of the rhythmites and investigating periodicities in bed thickness, our study aimed at reconstructing the mode of deposition of this enigmatic prodeltaic succession. We measured at high stratigraphic resolution 265 consecutive couplets, for a total thickness of 33 m. Individual beds have good lateral persistence of at least tens of meters and gradational to sharp, flat contacts. Observed sedimentary structures are concentrated on the coarser portion of the couplets and mostly consist of parallel and wavy lamination, with subordinate ripple cross-lamination and localized internal scours. Bioturbation appears low in intensity or absent. Most notably, grain size analysis performed with laser diffraction techniques on several couplets shows a consistent pattern of inverse grading transitioning to normal grading. The cumulative evidence of these sedimentological features indicates that deposition of the rhythmites was accomplished via hyperpycnal flows, each couplet most likely representing an individual event in a setting characterized by high overall depositional rates. We performed time series analysis on bed thickness of

  18. Fluidized Bed Asbestos Sampler Design and Testing

    SciTech Connect

    Karen E. Wright; Barry H. O'Brien

    2007-12-01

    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

  19. Processes limiting mussel bed restoration in the Wadden-Sea

    NASA Astrophysics Data System (ADS)

    de Paoli, Hélène; van de Koppel, Johan; van der Zee, Els; Kangeri, Arno; van Belzen, Jim; Holthuijsen, Sander; van den Berg, Aniek; Herman, Peter; Olff, Han; van der Heide, Tjisse

    2015-09-01

    This paper reports on experimental restoration of mussel beds in the Wadden Sea and the processes that might limit successful restoration of this foundation species (i.e. substrate, predation, hydrodynamics). The importance of substrate, predation, hydrodynamic conditions and location on mussel restoration success was studied using artificially created mussel beds. Experimental beds established on a stable substrate (coir net) were compared with control beds established on sand, at three locations in the Wadden Sea. Their persistence was followed over time. The results revealed a near disappearance of all experimental beds in just over 7 months. Providing a stable substrate did not improve mussel survival. Predation could not explain the disappearance of the beds, as the maximal predation rate by birds was found to be insufficient to have a significant effect on mussel cover. Differences in wave conditions alone could also not explain the variation in decline of mussel cover between the locations. However, the gradual disappearance of mussels from the seaward side of the bed strongly suggested that hydrodynamic conditions (i.e. combined effects of waves and current) played an important role in the poor persistence of the artificial beds. Our results highlight the fact that restoration of mussel beds in dynamic areas cannot simply be implemented by mussel transplantation, particularly if additional measures to prevent wave losses are not taken, even when artificial substrate is provided to facilitate mussel adhesion.

  20. Laboratory singing sand avalanches.

    PubMed

    Dagois-Bohy, Simon; Ngo, Sandrine; du Pont, Sylvain Courrech; Douady, Stéphane

    2010-02-01

    Some desert sand dunes have the peculiar ability to emit a loud sound up to 110 dB, with a well-defined frequency: this phenomenon, known since early travelers (Darwin, Marco Polo, etc.), has been called the song of dunes. But only in late 19th century scientific observations were made, showing three important characteristics of singing dunes: first, not all dunes sing, but all the singing dunes are composed of dry and well-sorted sand; second, this sound occurs spontaneously during avalanches on a slip face; third this is not the only way to produce sound with this sand. More recent field observations have shown that during avalanches, the sound frequency does not depend on the dune size or shape, but on the grain diameter only, and scales as the square root of g/d--with g the gravity and d the diameter of the grains--explaining why all the singing dunes in the same vicinity sing at the same frequency. We have been able to reproduce these singing avalanches in laboratory on a hard plate, which made possible to study them more accurately than on the field. Signals of accelerometers at the flowing surface of the avalanche are compared to signals of microphones placed above, and it evidences a very strong vibration of the flowing layer at the same frequency as on the field, responsible for the emission of sound. Moreover, other characteristics of the booming dunes are reproduced and analyzed, such as a threshold under which no sound is produced, or beats in the sound that appears when the flow is too large. Finally, the size of the coherence zones emitting sound has been measured and discussed.

  1. Sand Dunes in Hellas

    NASA Technical Reports Server (NTRS)

    2003-01-01

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

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

  2. Fortune Cookie Sand Dunes

    NASA Technical Reports Server (NTRS)

    2003-01-01

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

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

  3. Sand Dunes, Afghanistan

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This ASTER image covers an area of 10.5 x 15 km in southern Afghanistan and was acquired on August 20, 2000. The band 3-2-1 composite shows part of an extensive field of barchan sand dunes south of Kandahar. The shape of the dunes indicates that the prevailing wind direction is from the west. The image is located at 30.7 degrees north latitude and 65.7 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  4. Sand dollar sites orogenesis

    NASA Astrophysics Data System (ADS)

    Amos, Dee

    2013-04-01

    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.

  5. Compressive behavior of fine sand.

    SciTech Connect

    Martin, Bradley E.; Kabir, Md. E.; Song, Bo; Chen, Wayne

    2010-04-01

    The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

  6. Collaborative Strategy on Bed Bugs

    EPA Pesticide Factsheets

    The Collaborative Strategy on Bed Bugs was developed by the Federal Bed Bug Workgroup to clarify the federal role in bed bug control and highlight ways that government, community, academia and private industry can work together on bed bug issues.

  7. Reconnaissance examination of selected oil-sand outcrops in Wyoming

    SciTech Connect

    Ver Ploeg, A.

    1986-08-01

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

  8. Studies of Phlebotomine Sand Flies.

    DTIC Science & Technology

    1980-08-31

    submitted for publication. iii 7. Key Words: Sand fly Lutzomyia Phlebotominae Phlebotomus Leishmaniasis 1i Note: Copies of this report are filed with...5 II. Sand Flies of the Central Amazon of Brazil. 2. De- scription of Lutzomyia (Triehophoromyia) ruii n. sp. . 28 III. A New Phlebotomine Sand...previously unknown in the Republic. These are Brvmptomyia hamata, B. galindoi, Lutzomyia odax, L. ovallesi, L. carpenteri, L. shannoni, L. texana, L

  9. Sand Waves in Tidal Channels

    DTIC Science & Technology

    2007-01-01

    example, in the Bahia Blanca Estuary (Argentina), the sand wave field terminated when the surficial sand sheet became too thin (Aliotta and Perillo... Rosa Island partially breached near the present-day location of the inlet mouth, but soon closed. It was reopened in March 1929 when the local...and Perillo, 1987) Bahia Blanca Estuary mean 11˚ max 30˚ mean 4˚ (Anthony and Leth, 2002) North Sea 2-4˚ 66 Figure 24. Sand wave

  10. Map showing high-purity silica sand of Middle Ordovician age in the Midwestern states

    USGS Publications Warehouse

    Ketner, Keith B.

    1979-01-01

    Certain quartz sands of Middle Ordovician age in the Midwestern States are well known for their purity and are exploited for a wide variety of industrial uses. The principal Middle Ordovician formations containing high-purity sands are the St. Peter Sandstone which crops out extensively from Minnesota to Arkansas; the Everton Formation principally of Arkansas; and the Oil Creek, McLish, and Tulip Creek Formations (all of the Simpson Group) of Oklahoma. The St. Peter and sandy beds in the other formations are commonly called "sandstones," but a more appropriate term is "sands" for in most fresh exposures they are completely uncemented or very weakly cemented. On exposure to air, uncemented sands usually become "case hardened" where evaporating ground water precipitates mineral matter at the surface; but this is a surficial effect. This report summarizes the available information on the extent of exposures, range of grain size, and chemical composition of the Middle Ordovician sands.

  11. The role of biophysical cohesion on subaqueous bed form size

    PubMed Central

    Schindler, Robert J.; Hope, Julie A.; Malarkey, Jonathan; Baas, Jaco H.; Peakall, Jeffrey; Manning, Andrew J.; Ye, Leiping; Simmons, Steve; Paterson, David M.; Aspden, Rebecca J.; Bass, Sarah J.; Davies, Alan G.; Lichtman, Ian D.; Thorne, Peter D.

    2016-01-01

    Abstract Biologically active, fine‐grained sediment forms abundant sedimentary deposits on Earth's surface, and mixed mud‐sand dominates many coasts, deltas, and estuaries. Our predictions of sediment transport and bed roughness in these environments presently rely on empirically based bed form predictors that are based exclusively on biologically inactive cohesionless silt, sand, and gravel. This approach underpins many paleoenvironmental reconstructions of sedimentary successions, which rely on analysis of cross‐stratification and bounding surfaces produced by migrating bed forms. Here we present controlled laboratory experiments that identify and quantify the influence of physical and biological cohesion on equilibrium bed form morphology. The results show the profound influence of biological cohesion on bed form size and identify how cohesive bonding mechanisms in different sediment mixtures govern the relationships. The findings highlight that existing bed form predictors require reformulation for combined biophysical cohesive effects in order to improve morphodynamic model predictions and to enhance the interpretations of these environments in the geological record. PMID:27011393

  12. Sand Sea in False Color

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The theme for the weeks of 1/17 and 1/24 is the north polar region of Mars as seen in false color THEMIS images. Ice/frost will typically appear as bright blue in color; dust mantled ice will appear in tones of red/orange.

    This image is of part of the northern sand sea. The small dunes in the image are bluer than the ice/dust filled central crater.

    Image information: VIS instrument. Latitude 73.7, Longitude 323 East (37 West). 40 meter/pixel resolution.

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

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

  13. Modeling the influence of storms on sand wave formation: A linear stability approach

    NASA Astrophysics Data System (ADS)

    Campmans, G. H. P.; Roos, P. C.; de Vriend, H. J.; Hulscher, S. J. M. H.

    2017-04-01

    We present an idealized process-based morphodynamic model to study the effect of storms on sand wave formation. To this end, we include wind waves, wind-driven flow and, in addition to bed load transport, suspended load sediment transport. A linear stability analysis is applied to systematically study the influence of wave and wind conditions on growth and migration rates of small-amplitude wavy bed undulations. The effects of the wind and waves of various magnitudes and directions are investigated. Waves turn out to decrease the growth rate of sand waves, because their effect on the downhill gravitational transport component is stronger than their growth-enhancing effect. The wind wave effect is strongest for wind waves perpendicular to the tidal current. In the case of a symmetrical tidal current, wind-driven flow tends to breach the symmetry, thus causing sand wave migration. Wind effects on sand wave behavior are strongly influenced by the Coriolis effect, in magnitude as well as direction. Stirring due to wind waves enhances sand wave migration. Next to bed load transport, suspended load also has a growing and a decaying mechanism, being the perturbed flow and the perturbed suspended sediment concentration respectively. The decaying mechanism outcompetes the growing mechanism for bed forms with shorter wavelengths, resulting in an increase in the preferred wavelength. Wind waves increase the growth rate due to suspended load, but this is outcompeted by the reduction in growth rate by wind waves due to bed load transport. We conclude that storms significantly influence sand wave dynamics in their formation stage.

  14. Thermofluid effect on energy storage in fluidized bed reactor

    NASA Astrophysics Data System (ADS)

    Mahfoudi, Nadjiba; El Ganaoui, Mohammed; Moummi, Abdelhafid

    2016-05-01

    The development of innovative systems of heat storage is imperative to improve the efficiency of the existing systems used in the thermal solar energy applications. Several techniques were developed and realized in this context. The technology of the sand fluidized bed (sandTES) offers a promising alternative to the current state-of-the-art of the heat storage systems, such as fixed bed using a storage materials, as sand, ceramic, and stones, etc. Indeed, the use of the fluidization technique allows an effective heat transfer to the solid particles. With the sand, an important capacity of storage is obtained by an economic and ecological material [N. Mahfoudi, A. Moummi, M. El Ganaoui, Appl. Mech. Mater. 621, 214 (2014); N. Mahfoudi, A. Khachkouch, A. Moummi B. Benhaoua, M. El Ganaoui, Mech. Ind. 16, 411 (2015); N. Mahfoudi, A. Moummi, M. El Ganaoui, F. Mnasri, K.M. Aboudou, 3e Colloque internationale Francophone d"énergétique et mécanique, Comores, 2014, p. 91]. This paper presents a CFD simulation of the hydrodynamics and the thermal transient behavior of a fluidized bed reactor of sand, to determine the characteristics of storage. The simulation shows a symmetry breaking that occurs and gave way to chaotic transient generation of bubble formation after 3 s. Furthermore, the predicted average temperature of the solid phase (sand) increases gradually versus the time with a gain of 1 °C in an interval of 10 s. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  15. In Situ Erosion Flume (ISEF): determination of bed-shear stress and erosion of a kaolinite bed

    NASA Astrophysics Data System (ADS)

    Houwing, Erik-Jan; van Rijn, Leo C.

    1998-06-01

    The strength of a cohesive sediment bed is difficult to determine and must be found experimentally from laboratory tests or through in situ field tests. A new in situ erosion instrument, the In situ Erosion Flume (ISEF), has been developed which is a circulating flow system in the vertical plane. The erosion process of sediment particles of the bed in the test section of the ISEF is related to the prevailing bed-shear stress induced by a unidirectional current. The bed-shear stress can be determined from the measured velocity profile in the test section assuming a logarithmic distribution in a vertical direction. The bed-shear stress equation has been calibrated under various conditions characterised by initiation of motion of sand and gravel particles at a flat bed where the bed-shear stresses mobilising the particles are known from the Shields curve. Three reproducibility tests were carried out under laboratory conditions. The bed consisted of kaolinite and was formed by sedimentation in still fresh water. The results of the three tests showed similar values. The erosion of a kaolinite sediment bed is more precisely determined under laboratory conditions by means of the ISEF. The results are compared with data from the literature. The ISEF is a relatively simple instrument for the determination of the strength of (cohesive) sediment beds. The results based on the ISEF measurements represent the minimum shear stress exerted at initiation of erosion of the bed, which will lead to the maximum shear strength of the top layer of the (cohesive) sediment bed.

  16. Sand and Dust on Mars

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Haberle, Robert M.

    1991-01-01

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

  17. Science Learning in the Sand.

    ERIC Educational Resources Information Center

    Sexton, Ursula

    1997-01-01

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

  18. Exercise Training During Bed Rest Attenuates Deconditioning

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Hargens, Alan R. (Technical Monitor)

    1995-01-01

    A 30-day 6 deg. head-down bed rest study was conducted to evaluate high-intensity, short-duration, alternating isotonic cycle ergometer exercise (ITE) training and high-intensity intermittent isokinetic exercise (IKE) training regiments designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels throughout prolonged bed rest. Other elements of the deconditioning (acclimation) syndrome, such as proprioception, psychological performance, hypovolemia, water balance, body composition, and orthostatic tolerance, were also measured. Compared with response during bed rest of the no exercise (NOE) control group: the ITE training regimen (a) maintained work capacity (peak VO2), (b) maintained plasma and red cell volume, (c) induced positive body water balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the IKE training regimen (a) attenuated the decrease in peak VO2 by 50%, (b) attenuated loss of red cell volume by 40%, but had no effect on loss of plasma volume, (c) induced positive body water balance, (d) had no adverse effect on quality of sleep or concentration, and (e) had no effect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulated by duration and intensity of ITE or IKE training regiments, and that several different training protocols will be required to maintain or restore physiological and psychological performance of individuals confined to prolonged bed rest.

  19. Intrawave sand suspension in the shoaling and surf zone of a field-scale laboratory beach

    NASA Astrophysics Data System (ADS)

    Brinkkemper, J. A.; Bakker, A. T. M.; Ruessink, B. G.

    2017-01-01

    Short-wave sand transport in morphodynamic models is often based solely on the near-bed wave-orbital motion, thereby neglecting the effect of ripple-induced and surface-induced turbulence on sand transport processes. Here sand stirring was studied using measurements of the wave-orbital motion, turbulence, ripple characteristics, and sand concentration collected on a field-scale laboratory beach under conditions ranging from irregular nonbreaking waves above vortex ripples to plunging waves and bores above subdued bed forms. Turbulence and sand concentration were analyzed as individual events and in a wave phase-averaged sense. The fraction of turbulence events related to suspension events is relatively high (˜50%), especially beneath plunging waves. Beneath nonbreaking waves with vortex ripples, the sand concentration close to the bed peaks right after the maximum positive wave-orbital motion and shows a marked phase lag in the vertical, although the peak in concentration at higher elevations does not shift to beyond the positive to negative flow reversal. Under plunging waves, concentration peaks beneath the wavefront without any notable phase lags in the vertical. In the inner-surf zone (bores), the sand concentration remains phase coupled to positive wave-orbital motion, but the concentration decreases with distance toward the shoreline. On the whole, our observations demonstrate that the wave-driven suspended load transport is onshore and largest beneath plunging waves, while it is small and can also be offshore beneath shoaling waves. To accurately predict wave-driven sand transport in morphodynamic models, the effect of surface-induced turbulence beneath plunging waves should thus be included.

  20. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  1. Sand and Water

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 7 November 2003

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

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

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

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

  2. Model of Fluidized Bed Containing Reacting Solids and Gases

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Lathouwers, Danny

    2003-01-01

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

  3. Petrology of Potomac Group sands in Fairfax County, Virginia

    USGS Publications Warehouse

    Lindholm, Roy C.

    1978-01-01

    The Potomac Group sands sampled in Fairfax County are dominantly microcline-rich lithic arkoses. Quartz averages 59%, microcline 25%, plagioclase less than 1% and lithic grains 16%. Most sands are texturally submature and medium grained. Microcline is somewhat more abundant in the deeper beds in the subsurface than in the shallow subsurface and outcrop sections, with quartz correspondingly more abundant at the surface. Zircon is the only abundant non-opaque heavy mineral in the outcrop section as well as in the shallow subsurface, but tourmaline, rutile and staurolite are also common. In contrast, the lower beds in the subsurface have a heavy mineral assemblage with zircon, garnet and apatite as the dominant species. Several alternative explanations for the vertical variation in mineral assemblages from less to more stable types in the Potomac Group sands are possible: 1) removal of primary Piedmont apatite-bearing igneous and garnet-bearing metamorphic source rock by erosion or burial by overlapping Potomac Group sediments, 2) deep weathering of primary Piedmont source areas and destruction of less stable minerals (apatite and garnet) in Cretaceous time, 3) destruction of less stable minerals (apatite and garnet) near the surface and in the shallow subsurface by post-Cretaceous deep weathering and/or intrastratal solution.

  4. Field observations of wind profiles and sand fluxes above the windward slope of a sand dune before and after the establishment of semi-buried straw checkerboard barriers

    NASA Astrophysics Data System (ADS)

    Zhang, Chunlai; Li, Qing; Zhou, Na; Zhang, Jiaqiong; Kang, Liqiang; Shen, Yaping; Jia, Wenru

    2016-03-01

    Straw checkerboard barriers are effective and widely used measures to control near-surface sand flow. The present study measured the wind profiles and sand mass flux above the windward slope of a transverse dune before and after the establishment of semi-buried straw checkerboards. The 0.2 m high checkerboards enhanced the aerodynamic roughness length to larger than 0.02 m, which was two to three orders of magnitude higher than that of the bare sand. The modified Charnock model predicted the roughness length of the sand bed during saltation well, with Cm = 0.138 ± 0.003. For the checkerboards, z0 increased slowly to a level around 0.037 m with increasing wind velocity and the rate of increase tended to slow down in strong wind. The barriers reduced sand flux and altered its vertical distribution. The total height-integrated dimensionless mass flux of saltating particles (q0) above bare sand followed the relationship ln q0 = a + b(u∗t/u∗) + c(u∗t/u∗)2, with a peak at u∗/u∗t ≈ 2, whereas a possible peak appeared at u∗/u∗t ≈ 1.5 above 1 m × 1 m straw checkerboards. The vertical distribution of mass flux above these barriers resembled an "elephant trunk", with maximum mass flux at 0.05-0.2 m above the bed, in contrast with the continuously and rapidly decreasing mass flux with increasing height above the bare sand. The influences of the barriers on the wind and sand flow prevent dune movement and alter the evolution of dune morphology.

  5. Red Sky with Red Mesa

    ScienceCinema

    None

    2016-07-12

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

  6. Bed material transport in the Virgin River, Utah

    USGS Publications Warehouse

    Andrews, E.D.

    2000-01-01

    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.

  7. Sand fly control in Kenya with residual pesticide application on HESCO barriers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    US military operations in hot-arid regions still face significant impacts from mosquito and sand fly vectors of diseases. Personal protective measures (PPM) such as DEET or treated bed nets and clothing can reduce contact with disease vectors and nuisance insects; however, irregular use of PPM coupl...

  8. Sand, Syrup and Supervolcanoes

    NASA Astrophysics Data System (ADS)

    Kennedy, B.; Jellinek, M.; Stix, J.

    2006-12-01

    Supervolcanic eruptions are amongst the most awesome events in the history of the Earth. A supervolcano can erupt thousands of cubic kilometers of ash devastating entire countries and changing the climate for decades. During the eruption, the magma chamber partially empties and collapses. As the chamber collapses at depth, a massive subsidence pit develops at the surface, called a caldera, some calderas can be the size of the entire San Francisco Bay Area. Fortunately, a supervolcano of this size has not erupted since the development of modern man. Due to the infrequency and massive scale of these eruptions, volcanologists do not yet fully understand how calderas form and how the eruption is affected by the roof collapse and vice versa. Therefore, simple analogue experiments are amongst the best ways to understand these eruptions. We present two of these experiments that can be fun, cheap, and helpful to high school and university instructors to demonstrate caldera formation. The first experiment illustrates how magma chamber roofs collapse to produce different style calderas, the second experiment demonstrates how the magma in the chamber affects the collapse style and magma mixing during a supervolcanic eruption. The collapse of a magma chamber can be demonstrated in a simple sandbox containing a buried balloon filled with air connected to a tube that leads out of the sandbox. At this small scale the buried balloon is a good analogue for a magma chamber and sand has an appropriate strength to represent the earths crust. Faults propagate through the sand in a similar way to faults propagating through the crust on a larger scale. To form a caldera just let the air erupt out of the balloon. This experiment can be used to investigate what controls the shape and structure of calderas. Different shaped balloons, and different burial depths all produce sand calderas with different sizes and structures. Additionally, experiments can be done that erupt only part of the

  9. Sediment transport and mixing depth on a coral reef sand apron

    NASA Astrophysics Data System (ADS)

    Vila-Concejo, Ana; Harris, Daniel L.; Power, Hannah E.; Shannon, Amelia M.; Webster, Jody M.

    2014-10-01

    This paper investigates the mechanics of sediment transport on a subtidal sand apron located on a coral reef environment. In this environment 100% of the sediment is carbonate bioclasts generated in situ. The sand apron is located on the back reef and only affected by waves during high tides. It is commonly accepted in the literature that sand aprons are features that prograde lagoonwards and that most of the progradation occurs during high-energy events. Measurements of water depths, waves, currents and near bed suspended sediment concentrations (all at 10 Hz) on the sand apron were undertaken over a nine day intensive field campaign over both spring and neap tides; waves and tides were also measured in the lagoon. The topography and bathymetry of the sand apron were measured and mixing depth was obtained on three transects using depth of disturbance rods. We found that sediment transport on sand aprons is not solely restricted to high-energy events but occurs on a daily basis during spring tides. The main factor controlling the sediment transport was the water depth above the bed, with depths of 2-2.3 m allowing waves to promote the most sediment transport. This corresponds to a depth over the reef crest of 1.6-1.9 m. The second most important control was waves; transport was observed when Hs on the apron was 0.1 m or greater. In contrast, current magnitude was not a controlling mechanism for sediment entrainment but did affect sediment transport. The morphology of the sand apron was shown to affect the direction of currents with the currents also expected to influence the morphology of the sand apron. The currents measured during this field campaign were aligned with a shallow channel in the sand apron. Mixing depths were small (< 2.5 cm) yet they were larger than the values predicted by empirical formulae for gentle siliciclastic ocean beaches.

  10. 2D DEM model of sand transport with wind interaction

    NASA Astrophysics Data System (ADS)

    Oger, L.; Valance, A.

    2013-06-01

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

  11. Transient response of sand bedforms to changes in flow

    NASA Astrophysics Data System (ADS)

    Martin, R. L.; Jerolmack, D. J.

    2011-12-01

    Lowland rivers commonly experience discharge variability spanning more than an order of magnitude, producing correspondingly large changes in bed morphology. However, field and lab studies indicate that bedform geometries lag changes in flow, producing hysteretic relationships between bed morphology, roughness, and water discharge. The ability of bedforms to maintain equilibrium with hydrodynamic flow variability thus depends on the timescale of transient bedform adjustment to flow. Here, we present results of flume experiments carried out at the Saint Anthony Falls Laboratory, University of Minnesota, in which we continuously tracked adjustment of sand bedform morphologies to abrupt changes in water discharge. We show how the timescale of bedform adjustment is driven by three primary factors: 1. directionality of adjustment, 2. preexisting bedform geometry, and 3. sediment flux. Directionality of adjustment (rising versus falling water discharge) determines whether bedforms grow quickly by irreversible merger (rising flows) or shrink slowly through secondary bedform cannibalization of relict larger bedforms (falling flows). Preexisting bedform geometry (height and length) determines the amount of bed deformation required for adjustment to new equilibrium, and sediment flux determines the rate at which this change is affected. These three factors all favor faster adjustment of bedforms to rising flows. We experimentally demonstrate this bedform adjustment hysteresis through a variety of increasing and decreasing discharge changes, across both sand ripple and dune regimes. Finally, we propose and validate a simple conceptual model for estimating the adjustment timescale based on sediment flux and equilibrium bedform geometry.

  12. Deep River Velocity and Sediment Profiles and the Suspended Sand Load,

    DTIC Science & Technology

    1963-02-01

    5.03 x IO~~ ATCHAFALAVA RIVER WIDTH : 1587 FT D 5, : 6.75 w 0 ~ FT SIMM ESPORT u : 6.66 FPS WATER TEMP. : 70 F d : 46.3 FT FINE SAND PORTION OP BED...1.34 * 10 3FT SIMM ESPORT ~ : 5.85 FPS WATCR TEMP. :69 ’F d : 47.7 FT FiNE SAND PORTION OP BED MATERIAL : 39.$ ~~ FIG. 16...DEC. 14,196 1 Q : 218,000 CF’S S : 336 *io ’~ ATCHAFALAVA RIVERWIDTH ?~ FPS WATER TEMP : løOx I0~~ FT SIMM ESPORT d : 4 1 .7 FT FINE SAND PORTION OF B

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

    USGS Publications Warehouse

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

    2009-01-01

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

  14. Fluidized-bed boilers

    SciTech Connect

    Makansi, J.; Schwieger, B.

    1982-08-01

    This report reviews the current state of atmospheric fluidized-bed combustion. The fundamentals of fluidized-bed combustion and design considerations are first discussed. Tables provide details of manufacturers, worldwide, and of the boilers now installed. Eight plants in various countries and burning a variety of fuels, are described more fully.

  15. Fluidized bed calciner apparatus

    DOEpatents

    Owen, Thomas J.; Klem, Jr., Michael J.; Cash, Robert J.

    1988-01-01

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

  16. Bed Bugs FAQs

    MedlinePlus

    ... allow them to fit into the smallest of spaces and stay there for long periods of time, even without a blood meal. Bed bugs are usually transported from place to place as people travel. The bed bugs travel in the seams and ...

  17. Red Hill

    EPA Pesticide Factsheets

    Information about the Red Hill Bulk Fuel Storage Facility in Hawaii Administrative Order on Consent (AOC), an enforceable agreement of the Hawaii Department of Health, the Environmental Protection Agency, and the U.S. Navy -- Defense Logistics Agency.

  18. The Influence of Roughness and Pyrethroid Formulations on Bed Bug (Cimex lectularius L.) Resting Preferences.

    PubMed

    Hottel, Benjamin A; Pereira, Roberto M; Koehler, Philip G

    2015-05-12

    Two-choice tests were conducted to examine the effect of surface roughness on the resting preference of bed bugs, Cimex lectularius L., on copper, basswood, and acrylic materials. The influence of pyrethroid formulation applications on resting preferences was also evaluated. Bed bugs were given the choice of resting between two sanded halves of each material tested. One half was sanded with a P60 grit sandpaper and the other with a less rough P600 grit sandpaper. A significantly higher proportion of bed bugs chose to rest on the rougher P60 grit sanded half of all materials tested. Pyrethroid applications were made to either the P60 grit half or both halves of acrylic arenas and resting preferences were again assessed. Behavioral responses of bed bugs to pyrethroid formulation applications varied depending on the bed bug strain used and the formulation applied. Bed bugs would still rest on the P60 grit half when Suspend SC formulation (0.06% deltamethrin) was applied; however, an avoidance response was observed from a bed bug strain susceptible to D-Force aerosol formulations (0.06% deltamethrin). The avoidance behavior is likely attributed to one, more than one, or even an interaction of multiple spray constituents and not the active ingredient.

  19. The Influence of Roughness and Pyrethroid Formulations on Bed Bug (Cimex lectularius L.) Resting Preferences

    PubMed Central

    Hottel, Benjamin A.; Pereira, Roberto M.; Koehler, Philip G.

    2015-01-01

    Two-choice tests were conducted to examine the effect of surface roughness on the resting preference of bed bugs, Cimex lectularius L., on copper, basswood, and acrylic materials. The influence of pyrethroid formulation applications on resting preferences was also evaluated. Bed bugs were given the choice of resting between two sanded halves of each material tested. One half was sanded with a P60 grit sandpaper and the other with a less rough P600 grit sandpaper. A significantly higher proportion of bed bugs chose to rest on the rougher P60 grit sanded half of all materials tested. Pyrethroid applications were made to either the P60 grit half or both halves of acrylic arenas and resting preferences were again assessed. Behavioral responses of bed bugs to pyrethroid formulation applications varied depending on the bed bug strain used and the formulation applied. Bed bugs would still rest on the P60 grit half when Suspend SC formulation (0.06% deltamethrin) was applied; however, an avoidance response was observed from a bed bug strain susceptible to D-Force aerosol formulations (0.06% deltamethrin). The avoidance behavior is likely attributed to one, more than one, or even an interaction of multiple spray constituents and not the active ingredient. PMID:26463196

  20. The grain size gap and abrupt gravel-sand transitions in rivers due to suspension fallout

    NASA Astrophysics Data System (ADS)

    Lamb, Michael P.; Venditti, Jeremy G.

    2016-04-01

    Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1-5 mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between gravel- and sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or a bimodal sediment supply, but supporting evidence is lacking. Here we demonstrate that rivers dramatically lose the ability to transport sand as wash load where bed shear velocity drops below ~0.1 m/s, forcing an abrupt transition in bed-material grain size. Using thresholds for wash load and initial motion, we show that the gap emerges only for median bed-material grain sizes of ~1-5 mm due to Reynolds number dependencies in suspension transport. The grain size gap, therefore, is sensitive to material properties and gravity, with coarser gaps predicted on Mars and Titan.

  1. Filtration of nano-particles by a gas-solid fluidized bed.

    PubMed

    Liu, Kuang-Yu; Wey, Ming-Yen

    2007-08-17

    The filtration of 80 nm SiO2 and Al(2)O(3) particles in a gas stream using fluidized beds was studied. Silica sand and activated carbon (A.C.) were adopted as bed materials to filtrate 80 nm SiO2 and Al(2)O(3) particles. The collected particles were elutriated from the fluidized bed, so the filtration was a dynamic process and the variations of the removal efficiency with time were studied. Experimental results showed that the filtrations of 80 nm SiO2 and Al(2)O(3) particles with a bed material of silica sand were not dynamic processes but the filtration by A.C. was. The removal efficiencies for SiO2 and Al(2)O(3) particles using silica sand as bed material were held steady and found to be equal, between 86 and 93%. A.C. is considered to be more efficient than silica sand because it has a high specific surface area. However, the experimental data yield conflicting results. The removal efficiency of Al(2)O(3) particles fell from 92% initially to 80% at the end of test-a little lower than that obtained by filtration using silica sand. A higher voidage of A.C. than silica sand weakens the removal of nanoparticles since the diffusion mechanism dominates. The removal efficiency of SiO2 by A.C. decayed from 83 to 40% with time passed. The huge differences between the filtration efficiency of SiO2 and that of Al(2)O(3) particles by A.C. was associated with the extensive segregation of SiO2 and A.C. particles, which caused more SiO2 particles to move to the top of the bed, where they were elutriated. The weak inter-particle force for SiO2 decreased the removal efficiency also.

  2. Role of Vision and Mechanoreception in Bed Bug, Cimex lectularius L. Behavior

    PubMed Central

    Singh, Narinderpal; Wang, Changlu; Cooper, Richard

    2015-01-01

    The role of olfactory cues such as carbon dioxide, pheromones, and kairomones in bed bug, Cimex lectularius L. behavior has been demonstrated. However, the role of vision and mechanoreception in bed bug behavior is poorly understood. We investigated bed bug vision by determining their responses to different colors, vertical objects, and their ability to detect colors and vertical objects under low and complete dark conditions. Results show black and red paper harborages are preferred compared to yellow, green, blue, and white harborages. A bed bug trapping device with a black or red exterior surface was significantly more attractive to bed bugs than that with a white exterior surface. Bed bugs exhibited strong orientation behavior toward vertical objects. The height (15 vs. 30 cm tall) and color (brown vs. black) of the vertical object had no significant effect on orientation behavior of bed bugs. Bed bugs could differentiate color and detect vertical objects at very low background light conditions, but not in complete darkness. Bed bug preference to different substrate textures (mechanoreception) was also explored. Bed bugs preferred dyed tape compared to painted tape, textured painted plastic, and felt. These results revealed that substrate color, presence of vertical objects, and substrate texture affect host-seeking and harborage-searching behavior of bed bugs. Bed bugs may use a combination of vision, mechanoreception, and chemoreception to locate hosts and seek harborages. PMID:25748041

  3. Role of vision and mechanoreception in bed bug, Cimex lectularius L. behavior.

    PubMed

    Singh, Narinderpal; Wang, Changlu; Cooper, Richard

    2015-01-01

    The role of olfactory cues such as carbon dioxide, pheromones, and kairomones in bed bug, Cimex lectularius L. behavior has been demonstrated. However, the role of vision and mechanoreception in bed bug behavior is poorly understood. We investigated bed bug vision by determining their responses to different colors, vertical objects, and their ability to detect colors and vertical objects under low and complete dark conditions. Results show black and red paper harborages are preferred compared to yellow, green, blue, and white harborages. A bed bug trapping device with a black or red exterior surface was significantly more attractive to bed bugs than that with a white exterior surface. Bed bugs exhibited strong orientation behavior toward vertical objects. The height (15 vs. 30 cm tall) and color (brown vs. black) of the vertical object had no significant effect on orientation behavior of bed bugs. Bed bugs could differentiate color and detect vertical objects at very low background light conditions, but not in complete darkness. Bed bug preference to different substrate textures (mechanoreception) was also explored. Bed bugs preferred dyed tape compared to painted tape, textured painted plastic, and felt. These results revealed that substrate color, presence of vertical objects, and substrate texture affect host-seeking and harborage-searching behavior of bed bugs. Bed bugs may use a combination of vision, mechanoreception, and chemoreception to locate hosts and seek harborages.

  4. METHOD OF PROCESSING MONAZITE SAND

    DOEpatents

    Calkins, G.D.

    1957-10-29

    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.

  5. Turning patients over in bed

    MedlinePlus

    Roll patients in bed ... following steps should be followed: Explain to the patient what you are planning to do so the ... Stand on the side of the bed the patient will be turning towards and lower the bed ...

  6. Creep Behavior of Frozen Sand.

    DTIC Science & Technology

    1981-06-01

    Potash feldspar was the most abundant feldspar species. The clay minerals present were mica, illite, vermiculite and chlorite with considerable...5000X; a) Mica, b) Feldspar , c) Quartz -9- Page Fig. 111-5 Compaction - Freezing Mold 104 111-6 Cooling Curve for Partially Saturated MFS 105 111-7...aetween 74 and 250im size. The specific gravity of the sand was 2.67g/cm 3 . The mineralogy of the sand material was predominantly quartz and feldspars

  7. Oil recovery from tar sands

    SciTech Connect

    Boesiger, D.D.; Siefkin, J.M.

    1983-01-11

    A process for recovering oil from oil wet and particularly from oil-wet, acidic tar sands is described in which these sands are subjected to vigorous fluidization in the presence of water, air and a surfactant but in the absence of an extraneous hydrocarbon solvent. This step produces a multiphase mixture including an oil containing froth enabling gravity separation, E.G. In hydrocyclone.

  8. Modern Graywacke-Type Sands.

    PubMed

    Hollister, C D; Heezen, B C

    1964-12-18

    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.

  9. Preferences of dairy cows for three stall surface materials with small amounts of bedding.

    PubMed

    Norring, M; Manninen, E; de Passillé, A M; Rushen, J; Saloniemi, H

    2010-01-01

    Farmers' concerns about the economy, cost of labor, and hygiene have resulted in reduced use of organic bedding in stalls for dairy cows; however, the reduced use of organic bedding possibly impairs cow comfort. The effects of different stall surface materials were evaluated in an unheated building in which only a small amount of bedding was used. The lying time and preferences of 18 cows using 3 stall surface materials (concrete, soft rubber mat, and sand) were compared. All materials were lightly bedded with a small amount of straw, and the amount of straw added to each stall was measured. The cows only had access to stalls of one surface type while their lying time was observed. Lying times were longest on the rubber mats compared with other surfaces (rubber mat 768; concrete 727; sand 707+/-16 min/d). In a preference test, cows had access to 2 of the 3 types of stalls for 10 d and their stall preference was measured. Cows preferred stalls with rubber mats to stalls with a concrete floor (median 73 vs. 18 from a total of 160 observations per day; interquartile range was 27 and 12, respectively), but showed no preference for sand stalls compared with stalls with a concrete floor or with rubber mats. More straw was needed on sand stalls compared with concrete or mat (638+/-13 g/d on sand, 468+/-10 g/d on concrete, and 464+/-8 g/d on rubber mats). Lying times on bedded mats indicated that mats were comfortable for the cows. If availability or cost of bedding material requires limiting the amount of bedding used, rubber mats may help maintain cow comfort.

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

    NASA Astrophysics Data System (ADS)

    Sanford, Lawrence P.

    2008-10-01

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

  11. Sand control agent and process

    SciTech Connect

    Shu, P.; Donlon, W.P.; Strom, E.T.

    1992-04-07

    This patent describes a method for forming a gravel pack in a washed-out interval adjacent a borehole in an unconsolidated or loosely consolidated formation. It comprises perforating a cased borehole at an interval of the formation having a washed-out interval adjacent the borehole; placing sand into the washed-out interval via perforations in the borehole; injecting an aqueous solution of an alkali metal silicate into the interval through perforations contained in the borehole which solution is of a strength sufficient to react with an alcoholic solution of calcium salt to form a permeability retention cement having a porosity sufficient to exclude formation fines or sand; and injecting thereafter via the perforations a solvent containing a calcium salt into the interval containing sand in an amount sufficient to react with the alkali metal silicate at an interface with the solvent so as to form a calcium silicate cement which binds the sand whereupon the porosity of the sand-containing interval is reduced to a size sufficient to exclude the fines or sand while retaining the formation's permeability as the interface flows evenly and continually through the formation.

  12. Predicting bedforms and primary current stratification in cohesive mixtures of mud and sand

    NASA Astrophysics Data System (ADS)

    Best, J.; Jaco, B.; Peakall, J.

    2015-12-01

    The use of sedimentary structures as indicators of flow and sediment morphodynamics in ancient sediments is essential for reconstruction of formative flow conditions generated in a wide range of grain sizes and sedimentary environments. Yet, the vast majority of past research has concerned bedforms generated in essentially cohesionless sediments that lack the presence of mud within the flow and within the sediment bed itself. However, most sedimentary environments possess fine-grained sediments, with recent work demonstrating how the presence of such fine sediment may substantially modify the fluid dynamics of such flows. It is thus increasingly evident that the influence of mud, and the presence of cohesive forces, is essential to permit a fuller interpretation and understanding of many modern and ancient sedimentary successions. In this paper, we summarize on the fluid dynamics of turbulence modulation generated by the presence of fine suspended sediment, and use this knowledge to propose a new extended bedform phase diagram for bedforms generated in mixtures of sand and mud under rapidly decelerated flows. This diagram provides a phase space using the variables of yield strength and grain mobility as the abscissa and ordinate axes, respectively, and defines the stability fields of a range of bedforms generated under flows that have modified fluid dynamics due to the presence of suspended sediment within the flow. We also show data on a range of bedforms generated in such flows, from laboratory experiments and examples from ancient sediments, including: i) heterolithic stratification, comprising alternating laminae or layers of sand and mud; ii) the preservation of low amplitude bed-waves, large current ripples, and bed scours with intrascour composite bedforms; iii) low angle cross-lamination and long lenses and streaks of sand and mud formed by bed-waves; iv) complex stacking of reverse bedforms, mud layers and low-angle cross-lamination on the upstream face of

  13. Limited effectiveness of household sand filters for removal of arsenic from well water in North Vietnam.

    PubMed

    Ilmiawati, Cimi; Thang, Nguyen Dinh; Iida, Machiko; Maeda, Masao; Ohnuma, Shoko; Yajima, Ichiro; Ohgami, Nobutaka; Oshino, Reina; Al Hossain, M M Aeorangajeb; Ninomiya, Hiromasa; Kato, Masashi

    2016-12-01

    Since well water utilized for domestic purposes in the Red River Delta of North Vietnam has been reported to be polluted by arsenic, barium, iron, and manganese, household sand filters consisting of various components are used. Information regarding the effectiveness of various sand filters for removal of the four toxic elements in well water is limited. In this study, arsenic levels in 13/20 of well water samples and 1/7 of tap water samples exceeded World Health Organization (WHO) health-based guideline value for drinking water. Moreover, 2/20, 6/20, and 4/20 of well water samples had levels exceeding the present and previous guideline levels for barium, iron, and manganese, respectively. Levels of iron and manganese, but not arsenic, in well water treated by sand filters were lower than those in untreated water, although previous studies showed that sand filters removed all of those elements from water. A low ratio of iron/arsenic in well water may not be sufficient for efficient removal of arsenic from household sand filters. The levels of barium in well water treated by sand filters, especially a filter composed of sand and charcoal, were significantly lower than those in untreated water. Thus, we demonstrated characteristics of sand filters in North Vietnam.

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

    SciTech Connect

    Sauck, W.A.; Seng, D.L. )

    1994-04-01

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

  15. Bed Bug Information Clearinghouse

    EPA Pesticide Factsheets

    Its purpose is to help states, communities, and consumers in efforts to prevent and control bed bug infestations. Currently includes only reviewed material from federal/state/local government agencies, extension services, and universities.

  16. Bed Bug Tips

    EPA Pesticide Factsheets

    How to deal with bed bugs in one printable page. Ten tips include ensuring correct insect identification, reducing clutter, understand integrated pest management, using mattress and box spring encasements, and heat treatment.

  17. Tapered bed bioreactor

    DOEpatents

    Scott, Charles D.; Hancher, Charles W.

    1977-01-01

    A vertically oriented conically shaped column is used as a fluidized bed bioreactor wherein biologically catalyzed reactions are conducted in a continuous manner. The column utilizes a packing material a support having attached thereto a biologically active catalytic material.

  18. Particle fuel bed tests

    SciTech Connect

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H/sub 2/ for 12 hours with no visible reaction or weight loss.

  19. Moving-bed sorbents

    SciTech Connect

    Ayala, R.E.; Gupta, R.P.; Chuck, T.

    1995-12-01

    The objective of this program is to develop mixed-metal oxide sorbent formulations that are suitable for moving-bed, high-temperature, desulfurization of coal gas. Work continues on zinc titanates formulations and Z-sorb III sorbent.

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

    PubMed

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

    2015-02-01

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

  1. Test Bed For Telerobots

    NASA Technical Reports Server (NTRS)

    Matijevic, Jacob R.; Zimmerman, Wayne F.; Dolinsky, Shlomo

    1990-01-01

    Assembly of electromechanical and electronic equipment (including computers) constitutes test bed for development of advanced robotic systems for remote manipulation. Combines features not found in commercial systems. Its architecture allows easy growth in complexity and level of automation. System national resource for validation of new telerobotic technology. Intended primarily for robots used in outer space, test bed adapted to development of advanced terrestrial telerobotic systems for handling radioactive materials, dangerous chemicals, and explosives.

  2. Bed exit alarms.

    PubMed

    2004-09-01

    Bed-exit alarms alert caregivers that a patient who should not get out of bed unassisted is doing so. These alarms can help reduce the likelihood of falls and can promote speedy assistance to patients who have already fallen. But as we described in our May 2004 Guidance Article on bed-exit alarms, they don't themselves prevent falls. They are only effective if used as part of an overall fall-prevention program and with a clear understanding of their limitations. This Evaluation examines the effectiveness of 16 bed-exit alarms from seven suppliers. Our ratings focus primarily on each product's reliability in detecting bed-exit events and alerting caregivers, its ability to minimize nuisance alarms (alarms that sound even though the patient isn't leaving the bed or that sound while a caregiver is helping the patient to leave the bed), and its resistance to deliberate or inadvertent tampering. Twelve of the products use pressure-sensor-activated alarms (mainly sensor pads placed on or under the mattress); three use a cord that can attach to the patient's garment, alarming if the cord is pulled loose from the control unit; and one is a position-sensitive alarm attached to a leg cuff. All the products reliably detect attempted or successful bed exits. But they vary greatly in how effectively they alert staff, minimize nuisance alarms, and resist tampering. Ease of use and battery performance also vary for many units. Of the pressure-sensor units, three are rated Preferred. Those units meet most of our criteria and have no significant disadvantages. Five of the other pressure-sensor products are Acceptable, and the remaining four are Not Recommended. All three cord-activated alarms are rated Acceptable, as is the patient-worn alarm.

  3. Bed rest and immunity

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

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

  4. Large-Scale Sediment Routing: Development of a One-Dimensional Model Incorporating Sand Storage

    NASA Astrophysics Data System (ADS)

    Wiele, S. M.; Wilcock, P. R.; Grams, P. E.

    2005-12-01

    Routing sediment through long reaches and networks requires a balance between model efficiency, data availability, and accurate representation of sediment flux and storage. The first two often constrain the appropriate model to one dimension, but such models are unable to capture changes in sediment storage in side-channel environments, which are typically driven by two-dimensional transport fields. Side-channel environments are especially important in canyon channels. Routing of sand in canyon channels can be further complicated by transport of sand over a cobble or boulder bed and by remote locations, which can hinder measurement of channel shape. We have produced a one-dimensional model that routes water and sand through the Colorado River below Glen Canyon Dam in Arizona. Our model differs from conventional one-dimensional models in several significant ways: (1) exchange of sand between the main downstream current and eddies, which cannot be directly represented by a one-dimensional model, is included by parameterizing predictions over a wide range of conditions from a multidimensional model; (2) suspended-sand transport over an extremely rough and sparsely sand-covered bed, which is not accurately represented in conventional sand-transport relations or boundary conditions, is calculated in our model with newly developed algorithms (see Grams and others, this meeting); (3) the channel is represented by reach-averaged properties, thereby reducing data requirements and increasing model efficiency; and (4) the model is coupled with an unsteady-flow model, thereby accounting for frequent changes in discharge produced by variations in releases in this power-producing regulated river. Numerical models can contribute to the explanation of observed changes in sand storage, extrapolate field observations to unobserved flows, and evaluate alternative dam-operation strategies for preserving the sand resource. Model applications can address several significant management

  5. Arsenic removal from water using natural iron mineral-quartz sand columns.

    PubMed

    Guo, Huaming; Stüben, Doris; Berner, Zolt

    2007-05-15

    The study has investigated the feasibility of using siderite-coated quartz sand and/or hematite-coated quartz sand columns for removing As from water. Arsenic-spiked tap water and synthetic As solution with As concentrations from 200 to 500 mug/L were used for the experiments. Since three coating methods employed to prepare siderite-coated quartz sand and hematite-coated quartz sand had no significant impact on As adsorption in batch tests, the column fillings were produced by means of the simplest one involving mechanically mixing the Fe mineral with quartz sand. Fixed bed tests show that the combination of siderite-coated quartz sand and hematite-coated quartz sand greatly promoted the column performance in removing As and the presence of As(III) in the influent improved the removal efficiency of the column. The relatively low capacity in treating As-spiked tap water arose from the suppression of FeCO(3) dissolution in the presence of high HCO(3)(-) concentration (333 mg/L), which consequently limited the formation of fresh Fe(III) oxides. However, the H(2)O(2)-conditioning greatly increased As adsorption capacity of the column for remediating As-spiked tap water. The Toxicity Characteristic Leaching Procedure (TCLP) test shows that the spent adsorbents were not hazardous and could be safely disposed of to landfill.

  6. Evaluating process origins of sand-dominated fluvial stratigraphy

    NASA Astrophysics Data System (ADS)

    Chamberlin, E.; Hajek, E. A.

    2015-12-01

    Sand-dominated fluvial stratigraphy is often interpreted as indicating times of relatively slow subsidence because of the assumption that fine sediment (silt and clay) is reworked or bypassed during periods of low accommodation. However, sand-dominated successions may instead represent proximal, coarse-grained reaches of paleo-river basins and/or fluvial systems with a sandy sediment supply. Differentiating between these cases is critical for accurately interpreting mass-extraction profiles, basin-subsidence rates, and paleo-river avulsion and migration behavior from ancient fluvial deposits. We explore the degree to which sand-rich accumulations reflect supply-driven progradation or accommodation-limited reworking, by re-evaluating the Castlegate Sandstone (Utah, USA) and the upper Williams Fork Formation (Colorado, USA) - two Upper Cretaceous sandy fluvial deposits previously interpreted as having formed during periods of relatively low accommodation. Both units comprise amalgamated channel and bar deposits with minor intra-channel and overbank mudstones. To constrain relative reworking, we quantify the preservation of bar deposits in each unit using detailed facies and channel-deposit mapping, and compare bar-deposit preservation to expected preservation statistics generated with object-based models spanning a range of boundary conditions. To estimate the grain-size distribution of paleo-sediment input, we leverage results of experimental work that shows both bed-material deposits and accumulations on the downstream side of bars ("interbar fines") sample suspended and wash loads of active flows. We measure grain-size distributions of bar deposits and interbar fines to reconstruct the relative sandiness of paleo-sediment supplies for both systems. By using these novel approaches to test whether sand-rich fluvial deposits reflect river systems with accommodation-limited reworking and/or particularly sand-rich sediment loads, we can gain insight into large

  7. Geologic map of Great Sand Dunes National Park, Colorado

    USGS Publications Warehouse

    Madole, Richard F.; VanSistine, D. Paco; Romig, Joseph H.

    2016-10-20

    Geologic mapping was begun after a range fire swept the area of what is now the Great Sand Dunes National Park in April 2000. The park spans an area of 437 square kilometers (or about 169 square miles), of which 98 percent is blanketed by sediment of Quaternary age, the Holocene and Pleistocene Epochs; hence, this geologic map of the Great Sand Dunes National Park is essentially a surficial geologic map. These surficial deposits are diverse and include sediment of eolian (windblown), alluvial (stream and sheetwash), palustrine (wetlands and marshes), lacustrine (lake), and mass-wasting (landslides) origin. Sediment of middle and late Holocene age, from about 8,000 years ago to the present, covers about 80 percent of the park.Fluctuations in groundwater level during Holocene time caused wetlands on the nearby lowland that bounds the park on the west to alternately expand and contract. These fluctuations controlled the stability or instability of eolian sand deposits on the downwind (eastern) side of the lowland. When groundwater level rose, playas became lakes, and wet or marshy areas formed in many places. When the water table rose, spring-fed streams filled their channels and valley floors with sediment. Conversely, when groundwater level fell, spring-fed streams incised their valley floors, and lakes, ponds, and marshes dried up and became sources of windblown sand.Discharge in streams draining the west flank of the Sangre de Cristo Range is controlled primarily by snowmelt and flow is perennial until it reaches the mountain front, beyond which streams begin losing water at a high rate as the water soaks into the creek beds. Even streams originating in the larger drainage basins, such as Sand and Medano Creeks, generally do not extend much more than 4 km (about 2.5 miles) beyond where they exit the mountains.The Great Sand Dunes contain the tallest dunes (maximum height about 750 feet, or 230 m) in North America. These dunes cover an area of 72 square kilometers

  8. Non-linear effects on solute transfer between flowing water and a sediment bed.

    PubMed

    Higashino, Makoto; Stefan, Heinz G

    2011-11-15

    A previously developed model of periodic pore water flow in space and time, and associated solute transport in a stream bed of fine sand is extended to coarse sand and fine gravel. The pore water flow immediately below the sediment/water interface becomes intermittently a non-Darcy flow. The periodic pressure and velocity fluctuations considered are induced by near-bed coherent turbulent motions in the stream flow; they penetrate from the sediment/water interface into the sediment pore system and are described by a wave number (χ) and a period (T) that are given as functions of the shear velocity (U(∗)) between the flowing water and the sediment bed. The stream bed has a flat surface without bed forms. The flow field in the sediment pore system is described by the continuity equation and a resistance law that includes both viscous (Darcy) and non-linear (inertial) effects. Simulation results show that non-linear (inertial) effects near the sediment/water interface increase flow resistance and reduce mean flow velocities. Compared to pure Darcy flow, non-linear (inertial) effects reduce solute exchange rates between overlying water and the sediment bed but only by a moderate amount (less than 50%). Turbulent coherent flow structures in the stream flow enhance solute transfer in the pore system of a stream bed compared to pure molecular diffusion, but by much less than standing surface waves or bed forms.

  9. Disturbance of the inclined inserting-type sand fence to wind-sand flow fields and its sand control characteristics

    NASA Astrophysics Data System (ADS)

    Cheng, Jian-jun; Lei, Jia-qiang; Li, Sheng-yu; Wang, Hai-feng

    2016-06-01

    The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind-sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.

  10. Optimal array of sand fences

    PubMed Central

    Lima, Izael A.; Araújo, Ascânio D.; Parteli, Eric J. R.; Andrade, José S.; Herrmann, Hans J.

    2017-01-01

    Sand fences are widely applied to prevent soil erosion by wind in areas affected by desertification. Sand fences also provide a way to reduce the emission rate of dust particles, which is triggered mainly by the impacts of wind-blown sand grains onto the soil and affects the Earth’s climate. Many different types of fence have been designed and their effects on the sediment transport dynamics studied since many years. However, the search for the optimal array of fences has remained largely an empirical task. In order to achieve maximal soil protection using the minimal amount of fence material, a quantitative understanding of the flow profile over the relief encompassing the area to be protected including all employed fences is required. Here we use Computational Fluid Dynamics to calculate the average turbulent airflow through an array of fences as a function of the porosity, spacing and height of the fences. Specifically, we investigate the factors controlling the fraction of soil area over which the basal average wind shear velocity drops below the threshold for sand transport when the fences are applied. We introduce a cost function, given by the amount of material necessary to construct the fences. We find that, for typical sand-moving wind velocities, the optimal fence height (which minimizes this cost function) is around 50 cm, while using fences of height around 1.25 m leads to maximal cost. PMID:28338053

  11. Optimal array of sand fences

    NASA Astrophysics Data System (ADS)

    Lima, Izael A.; Araújo, Ascânio D.; Parteli, Eric J. R.; Andrade, José S.; Herrmann, Hans J.

    2017-03-01

    Sand fences are widely applied to prevent soil erosion by wind in areas affected by desertification. Sand fences also provide a way to reduce the emission rate of dust particles, which is triggered mainly by the impacts of wind-blown sand grains onto the soil and affects the Earth’s climate. Many different types of fence have been designed and their effects on the sediment transport dynamics studied since many years. However, the search for the optimal array of fences has remained largely an empirical task. In order to achieve maximal soil protection using the minimal amount of fence material, a quantitative understanding of the flow profile over the relief encompassing the area to be protected including all employed fences is required. Here we use Computational Fluid Dynamics to calculate the average turbulent airflow through an array of fences as a function of the porosity, spacing and height of the fences. Specifically, we investigate the factors controlling the fraction of soil area over which the basal average wind shear velocity drops below the threshold for sand transport when the fences are applied. We introduce a cost function, given by the amount of material necessary to construct the fences. We find that, for typical sand-moving wind velocities, the optimal fence height (which minimizes this cost function) is around 50 cm, while using fences of height around 1.25 m leads to maximal cost.

  12. Optimal array of sand fences.

    PubMed

    Lima, Izael A; Araújo, Ascânio D; Parteli, Eric J R; Andrade, José S; Herrmann, Hans J

    2017-03-24

    Sand fences are widely applied to prevent soil erosion by wind in areas affected by desertification. Sand fences also provide a way to reduce the emission rate of dust particles, which is triggered mainly by the impacts of wind-blown sand grains onto the soil and affects the Earth's climate. Many different types of fence have been designed and their effects on the sediment transport dynamics studied since many years. However, the search for the optimal array of fences has remained largely an empirical task. In order to achieve maximal soil protection using the minimal amount of fence material, a quantitative understanding of the flow profile over the relief encompassing the area to be protected including all employed fences is required. Here we use Computational Fluid Dynamics to calculate the average turbulent airflow through an array of fences as a function of the porosity, spacing and height of the fences. Specifically, we investigate the factors controlling the fraction of soil area over which the basal average wind shear velocity drops below the threshold for sand transport when the fences are applied. We introduce a cost function, given by the amount of material necessary to construct the fences. We find that, for typical sand-moving wind velocities, the optimal fence height (which minimizes this cost function) is around 50 cm, while using fences of height around 1.25 m leads to maximal cost.

  13. Control of bed height in a fluidized bed gasification system

    DOEpatents

    Mehta, Gautam I.; Rogers, Lynn M.

    1983-12-20

    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.

  14. Measuring bed load discharge in rivers: bedload-surrogate monitoring workshop Minneapolis, Minnesota, 11-14 April 2007

    USGS Publications Warehouse

    Gray, John R.; Laronne, Jonathan B.; Marr, Jeffrey D.G.

    2007-01-01

    The International Bedload-Surrogate Monitoring Workshop (http://www.nced.umn.edu/BRIC_2007.html), organized by the Bedload Research International Cooperative (BRIC; www.bedloadresearch.org), was held to assess and abet progress in continuous, semiautomated, or fully automated (surrogate) technologies for monitoring bed load discharge in gravel-, sand-, and mixed gravel-sand-bedded rivers. Direct bed load measurements, particularly at medium and high flows, during which most bed load occurs, tend to be time-consuming, expensive, and potentially hazardous. Surrogate technologies developed largely over the past decade and used at a number of research sites around the world show considerable promise toward providing relatively dense, robust, and quantifiably reliable bed load data sets. However, information on the efficacy of selected technologies for use in monitoring programs is needed, as is identification of the ways and means for bringing the most promising and practical of the technologies to fruition.

  15. Red blood cell decreases of microgravity

    NASA Technical Reports Server (NTRS)

    Johnson, P. C.

    1985-01-01

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

  16. Sand, gravel properties key to optimum designs

    SciTech Connect

    Oyeneyin, M.B.

    1998-01-26

    Successful gravel packed and screen well completions require a knowledge of sand as well as gravel textural properties. These completion methods keep sand and fines from entering the well bore, so that long-term production capacity of the well is ensured. This first of a three-part series will cover key factors that influence effective sand control. The concluding parts will present guidelines for both gravel packs and screens. Fines, more than load-bearing formation sands, pose the greater problem for the two sand exclusion techniques. Therefore, reservoir sand analysis is the main key for controlling sand. An integrated team approach to both sand control design and implementation from well planning through drilling to final completion is the best strategy for optimizing well performance in reservoirs with sand problems.

  17. Sand waves in environmental flows: Insights gained by coupling large-eddy simulation with morphodynamics

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Fotis; Khosronejad, Ali

    2016-02-01

    Sand waves arise in subaqueous and Aeolian environments as the result of the complex interaction between turbulent flows and mobile sand beds. They occur across a wide range of spatial scales, evolve at temporal scales much slower than the integral scale of the transporting turbulent flow, dominate river morphodynamics, undermine streambank stability and infrastructure during flooding, and sculpt terrestrial and extraterrestrial landscapes. In this paper, we present the vision for our work over the last ten years, which has sought to develop computational tools capable of simulating the coupled interactions of sand waves with turbulence across the broad range of relevant scales: from small-scale ripples in laboratory flumes to mega-dunes in large rivers. We review the computational advances that have enabled us to simulate the genesis and long-term evolution of arbitrarily large and complex sand dunes in turbulent flows using large-eddy simulation and summarize numerous novel physical insights derived from our simulations. Our findings explain the role of turbulent sweeps in the near-bed region as the primary mechanism for destabilizing the sand bed, show that the seeds of the emergent structure in dune fields lie in the heterogeneity of the turbulence and bed shear stress fluctuations over the initially flatbed, and elucidate how large dunes at equilibrium give rise to energetic coherent structures and modify the spectra of turbulence. We also discuss future challenges and our vision for advancing a data-driven simulation-based engineering science approach for site-specific simulations of river flooding.

  18. EPA-Registered Bed Bug Products

    MedlinePlus

    ... Pest Bed Bugs EPA Registered Bed Bug Products EPA-Registered Bed Bug Products Resources Bed Bug Main ... Bugs Tips Joint Statement on Bed Bug Control EPA has developed a search tool that can help ...

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

    PubMed

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

    2014-09-15

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

  20. Sands at Gusev Crater, Mars

    USGS Publications Warehouse

    Cabrol, Nathalie A.; Herkenhoff, Kenneth E.; Knoll, Andrew H.; Farmer, Jack D.; Arvidson, Raymond E.; Grin, E.A.; Li, Ron; Fenton, Lori; Cohen, B.; Bell, J.F.; Yingst, R. Aileen

    2014-01-01

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

  1. 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

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

    1991-01-01

    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

  2. The role of grain-size ratio in the mobility of mixed granular beds

    NASA Astrophysics Data System (ADS)

    Staudt, Franziska; Mullarney, Julia C.; Pilditch, Conrad A.; Huhn, Katrin

    2017-02-01

    The main goal of the study was to understand the effects of grain-size distribution on the stability of beds in the sand-silt range, which is a critical subject for the understanding of geomorphological processes in aquatic environments. Although theoretical models can explain the mobilization of a mixed bed, there is a clear lack in knowledge regarding the stabilizing effect of non-cohesive fine material. To connect existing findings, we analysed bed stability in relation to grain-size distribution in laboratory experiments. Erosion experiments in an annular flume were conducted using beds of different size compositions of spherical glass beads, i.e. a) the grain-size ratio RD = D50,coarse/D50,fine (the relative size of coarse and fine grains; D50 = 39-367 μm) and b) the amount of fines. Several glass-bead combinations with unimodal and bimodal grain-size distributions (RD = 3.9, 5.8, and 9.4) and varying fine fractions (10-40% dry weight) were subjected to increasing flow speeds (0.01-0.19 m s-1). Using acoustic Doppler velocimetry (ADV) and optical backscatter, the flow profile in the vicinity of the bed surface, the changes in bed morphology, and the suspended sediment concentration (SSC) were measured. A new method was developed to evaluate the bed-level changes detected by the ADV as a proxy for the bed mobility. We found different modes of bed mobility depending on the grain-size ratio. For low grain-size ratios, an increase in the fine fraction (to 40%) led to increased bed-level changes during the experiment and the mobilization of the mixed bed at the highest flow speed. For high ratios an increase in fine fraction (to 40%) led to a decrease of bed-level changes and the beds remained stable, i.e. no bed forms developed even at the highest flow speed. Therefore, increasing the amount of fine particles can lead to different modes of behaviour depending on the grain-size ratio. For a bimodal sediment bed with spherical grains under unidirectional flow

  3. Cross hospital bed management system.

    PubMed

    Abedian, S; Kazemi, H; Riazi, H; Bitaraf, E

    2014-01-01

    The lack of adequate numbers of hospital beds to accommodate the injured is a main problem in public hospitals. For control of occupancy of bed, we design a dynamic system that announces status of bed when it change with admission or discharge of a patient. This system provide a wide network in country for bed management, especially for ICU and CCU beds that help us to distribute injured patient in the hospitals.

  4. Treatment bed microbiological control

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    SciTech Connect

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

    1999-11-01

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

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

    USGS Publications Warehouse

    LeBlanc, Denis R.

    1984-01-01

    Secondarily treated domestic sewage has been disposed of on surface sand beds at the sewage treatment facility at Otis Air Force Base, Massachusetts, since 1936. Infiltration of the sewage through the sand beds into the underlying unconfined sand and gravel aquifer has resulted in a plume of sewage-contaminated ground water that is 2,500 to 3,500 feet wide, 75 feet thick, and more than 11,000 feet long. The plume extends south and southwest of the sand beds in the same direction as the regional flow of ground water, and is overlain by 20 to 50 feet of ground water derived from precipitation that recharges the aquifer. The bottom of the plume generally coincides with the contact between the permeable sand and gravel and underlying finer grained sediments. The distributions in the aquifer of specific conductance, temperature, boron, chloride, sodium, phosphorus, nitrogen (total of all species), ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. In ground water outside the plume, the detergent concentration is less than 0.1 milligrams per liter as MBAS (methylene blue active substances), the ammonia-nitrogen concentration is less than 0.1 milligrams per liter, the boron concentration is less than 50 micrograms per liter, and specific conductance is less than 80 mircromhos per centimeter. In the center of the plume, detergent concentrations as high as 2.6 milligrams per liter as MBAS, ammonia-nitrogen concentrations as high as 20 milligrams per liter, boron concentrations as high as 400 micrograms per liter, and specific conductance as high as 405 micromhos per centimeter were measured. Chloride, sodium, and boron are transported by the southward-flowing ground water without significant retardation, and seem to be diluted only by hydrodynamic dispersion. The movement of phosphorus is greatly restricted by sorption. Phosphorus concentrations do not exceed 0.05 milligrams per liter farther than 2,500 feet from the sand beds. Detergent

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

    SciTech Connect

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

    1983-03-01

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

  8. Fluidized bed coal desulfurization

    NASA Technical Reports Server (NTRS)

    Ravindram, M.

    1983-01-01

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

  9. Staged fluidized bed

    DOEpatents

    Mallon, R.G.

    1983-05-13

    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.

  10. Ability of organic and inorganic bedding materials to promote growth of environmental bacteria.

    PubMed

    Godden, S; Bey, R; Lorch, K; Farnsworth, R; Rapnicki, P

    2008-01-01

    The major objective of this study was to contrast the ability of 4 commonly utilized bedding materials to promote growth of environmental bacteria under controlled conditions. A second objective was to describe the relationship between bacterial growth and specific biochemical or nutritional properties of these bedding materials. Unused samples of clean sand (CS; n = 20), recycled sand (RS; n = 21), digested manure solids (DS; n = 15), and shavings (SH; n = 15) were collected from bedding storage areas on 49 commercial Minnesota and Wisconsin dairy farms. Sterilized bedding samples were inoculated with Klebsiella pneumoniae and Enterococcus faecium then incubated, in triplicate, for 72 h at 37 degrees C. Subsamples were collected after 0, 24, 48, and 72 h of incubation for culture and enumeration of bacteria. Subsamples of bedding were also tested for pH, total C content (%), and total N content (%). If bacterial growth occurred, peak levels were typically achieved within 24 h. Digested manure solids promoted the greatest amounts of growth of K. pneumoniae, followed by RS and then SH, whereas CS promoted the least. There would seem to be a tradeoff in selecting SH as a bedding material, because it supported moderate growth of K. pneumoniae but caused a rapid decline in the numbers of E. faecium. However, RS, CS, and DS each only supported relatively small amounts of growth of E. faecium, so the benefit of SH relative to other bedding materials is limited. High bedding pH may partially explain why some bedding materials supported growth of E. faecium (e.g., DS and RS). Both high bedding pH (e.g., as for DS or RS) and high total C (%) content (e.g., as for DS and SH) may partially explain why some bedding materials supported growth of K. pneumoniae.

  11. American Red Cross

    MedlinePlus

    ... Espanol Local Red Cross ( ) Change Chapter Edit Zip Code Edit Zip Code Shop the Red Cross Store Toggle Navigation Menu ... Espanol Local Red Cross ( ) Change Chapter Edit Zip Code Edit Zip Code Shop the Red Cross Store ...

  12. Spatial Distribution of Bed Particles in Natural Boulder-Bed Streams

    NASA Astrophysics Data System (ADS)

    Clancy, K. F.; Prestegaard, K. L.

    2001-12-01

    The Wolman pebble count is used to obtain the size distribution of bed particles in natural streams. Statistics such as median particle size (D50) are used in resistance calculations. Additional information such as bed particle heterogeneity may also be obtained from the particle distribution, which is used to predict sediment transport rates (Hey, 1979), (Ferguson, Prestegaard, Ashworth, 1989). Boulder-bed streams have an extreme range of particles in the particle size distribution ranging from sand size particles to particles larger than 0.5-m. A study of a natural boulder-bed reach demonstrated that the spatial distribution of the particles is a significant factor in predicting sediment transport and stream bed and bank stability. Further experiments were performed to test the limits of the spatial distribution's effect on sediment transport. Three stream reaches 40-m in length were selected with similar hydrologic characteristics and spatial distributions but varying average size particles. We used a grid 0.5 by 0.5-m and measured four particles within each grid cell. Digital photographs of the streambed were taken in each grid cell. The photographs were examined using image analysis software to obtain particle size and position of the largest particles (D84) within the reach's particle distribution. Cross section, topography and stream depth were surveyed. Velocity and velocity profiles were measured and recorded. With these data and additional surveys of bankfull floods, we tested the significance of the spatial distributions as average particle size decreases. The spatial distribution of streambed particles may provide information about stream valley formation, bank stability, sediment transport, and the growth rate of riparian vegetation.

  13. Diurnal patterns of blowing sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The diurnal pattern of blowing sand results from a complex process that involves the interaction between the sun, wind, and earth. During the day, solar heating produces thermal instability, which enhances the convective mixing of high momentum winds from the upper levels of the atmosphere to the s...

  14. V-2 at White Sands

    NASA Technical Reports Server (NTRS)

    1947-01-01

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

  15. Geology on a Sand Budget

    ERIC Educational Resources Information Center

    Kane, Jacqueline

    2004-01-01

    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…

  16. Sand and Water Table Play

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  17. Registration of 'Centennial' Sand Bluestem

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Centennial’ sand bluestem (PI 670042, Andropogon hallii Hack.) is a synthetic variety selected for greater percentage seed germination and percentage seedling establishment under field conditions. Centennial was tested under the experimental designation of ‘AB-Medium Syn-2’. Two cycles of recurren...

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

    NASA Astrophysics Data System (ADS)

    Nittrouer, J. A.; Viparelli, E.

    2013-12-01

    The Mississippi Delta is presently undergoing a catastrophic drowning, whereby 5000 km2 of low-lying wetlands have converted to open water. This land loss is primarily the result of: a) relative sea-level rise, occurring due to the combined effect of rapid subsidence associated with subsurface fluids extraction and eustatic rise; b) leveeing and damming of the river and its tributaries, which restricts sediment delivery to and dispersal within the delta; and c) severe excavation of the delta for navigation channels. It has been argued that continued net land loss of the Mississippi Delta is inevitable due to declining measured total (sand and mud) suspended sediment loads over the past 6 decades. However, recent research has documented that the key to delta growth is deposition of sand, which accounts for ~50-70% of modern and ancient (up to 9 m.a.) Mississippi Delta deposits, but comprises only ~20% of the sampled portion of the total load. Here we present new analysis of existing data to show that sand transport has not diminished since dam construction. Furthermore, we produce a numerical model based on the mass balance of bed material loads over the lower 1600 km of the Mississippi River to show that mining of sand from the channel bed continues to replenish downstream sand loads. For example, our model results indicate that it requires approximately 240 years for a reduced sand load to reach the delta apex. Furthermore, our calculations indicate that sand load at the delta apex is reduced by a noticeable amount (17%) only after about 600 years. We also show how channel bed elevations are predicted to change over the lower 1600 km of the river channel due to channel mining. Channel-bed degradation is greatest at the upstream end of the study reach and decreases downstream. After 300 years the wave of significant degradation has just passed ~800 km downstream, or roughly half of our model domain. These results are in contrast to the measurements which concern

  19. Control methods for remediation of ash-related problems in fluidized-bed combustors

    SciTech Connect

    Vuthaluru, H.B.; Zhang, D.

    1999-07-01

    The paper reports on investigations into control methodologies for mitigating ash-related problems such as particle agglomeration and bed defluidization during fluidized-bed combustion of low-rank coals. A laboratory scale spouted bed combustor is used to study the effectiveness of control methodologies. In the present work, two control methods are investigated viz., the use of alternative bed materials and pretreatment of coal. Bauxite and calcined sillimanite are used as alternative bed materials in the spouted bed combustor while burning South Australian low-rank coal. Samples of the same coal subjected to Al pretreatment, water washing and acid washing are also tested in the spouted bed combustor. Experiments showed that both methods are effective to different extents in reducing ash-related problems. Tests with calcined sillimanite and bauxite (as the bed material) showed trouble free operation for longer periods (7--12 hr at 800 C and 3--5 hr at 850 C) than with sand runs at the same bed temperatures. Al pretreatment and water-washing were also found to be effective and resulted in extended combustion operation. Al enrichment in ash coating of bed particles has been identified as the main mechanism for prevention of agglomeration and defluidization by these control methodologies. For water-washing, the principal reason behind agglomeration and defluidization control is the reduction in sodium levels.

  20. Armoring, stability, and transport driven by fluid flow over a granular bed

    NASA Astrophysics Data System (ADS)

    Allen, Benjamin; Kudrolli, Arshad

    2015-03-01

    We discuss experiments investigating the evolution of a granular bed by a fluid flow as a function of shear rate at the fluid-bed interface. This is a model system to investigate a variety of physical examples including wind blowing over sand, sediment transport in rivers, tidal flows interacting with beaches, flows in slurry pipelines, and sand proppants in hydraulic fracturing. In order to examine the onset and entrainment of the granular bed under steady state conditions, we have constructed a novel conical rheometer system which allows a variable amount of shear to be applied to the granular bed. The grain-fluid system is index matched so that we can visualize the grains away from the sides as well as visualize the fluid flow above and below the interface by using fluorescent tracer particles. We demonstrate that the onset of erosion arises as particles rotate out of their stable position highlighting the importance of torque balance to onset. We find significant armoring of the bed, as the bed is sheared by the fluid flow. Above onset, at least three distinct regions of bed mobility can be found. We will discuss the measured integrated granular flux as a function of shear rate and compare them with empirical laws found in the geophysical literature. Supported by NSF Grant Number CBET 1335928.

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

    PubMed

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

    2013-01-01

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

  2. Distributor for multistage fluidized beds

    SciTech Connect

    Wormser, A.

    1992-06-16

    This patent describes a multibed fluidized bed system. It comprises a fluidized bed vessel having a casing surrounding a first distributor and a second distributor downstream from the first distributor; a first bed material placed on the first distributor and a second bed material placed on the second distributor; each of the bed materials having an angle of repose; and wherein the angle formed by the substantially straight elongated tubular passages and the upper surface is less than the angle of repose of the second bed material.

  3. Fluid bed material transfer method

    DOEpatents

    Pinske, Jr., Edward E.

    1994-01-01

    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.

  4. Apparatus for controlling fluidized beds

    DOEpatents

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

    1987-05-12

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

  5. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, Amirali G.; Patel, Jitendra G.

    1987-05-12

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

  6. Effect of sand and rubber surface on the lying behavior of lame dairy cows in hospital pens.

    PubMed

    Bak, A S; Herskin, M S; Jensen, M B

    2016-04-01

    Housing lame cows in designated hospital pens with a soft surface may lessen the pain the animals feel when lying and changing position. This study investigated the effect of the lying surface on the behavior of lame cows in hospital pens. Thirty-two lame dairy cows were kept in individual hospital pens, provided with either 30-cm deep-bedded sand or 24-mm rubber mats during 24 h in a crossover design. On each surface, the lying behavior of each cow was recorded during 18 h. On deep-bedded sand, cows lay down more and changed position more often than when housed on the rubber surface. Furthermore, a shorter duration of lying down and getting up movements and a shorter duration of lying intention movements were observed. These results suggest that lame dairy cows are more reluctant to change position on rubber compared with sand, and that sand is more comfortable to lie on. Thus, deep bedding such as sand may provide better lying comfort for lame cows than an unbedded rubber surface.

  7. Virtual Test Bed

    DTIC Science & Technology

    2016-06-07

    project is to develop a benchmark system for evaluating models for predicting the characteristics of ocean wind waves. SCIENTIFIC OBJECTIVES A...to be assembled within the virtual test bed. Wind fields for running these tests will be obtained from Oceanweather, Inc. from a separate ONR

  8. Bed Bug Myths

    EPA Pesticide Factsheets

    Learn the truth about bed bugs, such as how easy they are to see with the naked eye, their preferred habitat, whether they transmit diseases, their public health effects, and whether pesticides are the best way to deal with an infestation.

  9. MULTISTAGE FLUIDIZED BED REACTOR

    DOEpatents

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

    1959-11-01

    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.

  10. Sand and Water Table Buying Guide.

    ERIC Educational Resources Information Center

    Morris, Susan

    1990-01-01

    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)

  11. Seismoacoustic Waves in Water-Covered Sand

    DTIC Science & Technology

    1999-12-01

    pdrtially buried inclusions such as seashells and sand dollars. This section presents the first experimental results on wedge waves propagating along the...sand dollar skeleton in air and in water. Further research is needed to characterize the seismoacoustic response of seashells and sand dollars.’, Thick

  12. Treating tar sands formations with karsted zones

    DOEpatents

    Vinegar, Harold J.; Karanikas, John Michael

    2010-03-09

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

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

    USGS Publications Warehouse

    McKee, Edwin Dinwiddie

    1989-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Vassilakos, Gregory J.; Hardy, Robin C.

    2012-01-01

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

  15. Understanding the fate of organic micropollutants in sand and granular activated carbon biofiltration systems.

    PubMed

    Paredes, L; Fernandez-Fontaina, E; Lema, J M; Omil, F; Carballa, M

    2016-05-01

    In this study, sand and granular activated carbon (GAC) biofilters were comparatively assessed as post-treatment technologies of secondary effluents, including the fate of 18 organic micropollutants (OMPs). To determine the contribution of adsorption and biotransformation in OMP removal, four reactors were operated (two biofilters (with biological activity) and two filters (without biological activity)). In addition, the influence of empty bed contact time (EBCT), ranging from 0.012 to 3.2d, and type of secondary effluent (anaerobic and aerobic) were evaluated. Organic matter, ammonium and nitrate were removed in both biofilters, being their adsorption higher on GAC than on sand. According to the behaviour exhibited, OMPs were classified in three different categories: I) biotransformation and high adsorption on GAC and sand (galaxolide, tonalide, celestolide and triclosan), II) biotransformation, high adsorption on GAC but low or null adsorption on sand (ibuprofen, naproxen, fluoxetine, erythromycin, roxythromycim, sulfamethoxazole, trimethoprim, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol), and, III) only adsorption on GAC (carbamazepine, diazepam and diclofenac). No influence of EBCT (in the range tested) and type of secondary effluent was observed in GAC reactors, whereas saturation and kinetic limitation of biotransformation were observed in sand reactors. Taking into account that most of the organic micropollutants studied (around 60%) fell into category II, biotransformation is crucial for the elimination of OMPs in sand biofilters.

  16. Effects of gasifying conditions and bed materials on fluidized bed steam gasification of wood biomass.

    PubMed

    Weerachanchai, Piyarat; Horio, Masayuki; Tangsathitkulchai, Chaiyot

    2009-02-01

    The effect of steam gasification conditions on products properties was investigated in a bubbling fluidized bed reactor, using larch wood as the starting material. For bed material effect, calcined limestone and calcined waste concrete gave high content of H(2) and CO(2), while silica sand provided the high content of CO. At 650 degrees C, calcined limestone proved to be most effective for tar adsorption and showed high ability to adsorb CO(2) in bed. At 750 degrees C it could not capture CO(2) but still gave the highest cold gas efficiency (% LHV) of 79.61%. Steam gasification gave higher amount of gas product and higher H(2)/CO ratio than those obtained with N(2) pyrolysis. The combined use of calcined limestone and calcined waste concrete with equal proportion contributed relatively the same gas composition, gas yield and cold gas efficiency as those of calcined limestone, but showed less attrition, sintering, and agglomeration propensities similar to the use of calcined waste concrete alone.

  17. Sand Waves. Report 1. Sand Wave Shoaling in Navigation Channels

    DTIC Science & Technology

    1992-09-01

    heights range from 0.8 m in the Minas Basin, Bay of Fundy (Dalrymple 1984) to 6.0 m in the Bahia Blanca Estuary, Argentina (Aliotta and Perillo 1987...26 PART IV: SITE-SPECIFIC SAND WAVE SHOALING PROBLEMS .. ........ 30 Columbia River Navigation Channel ........ ............... .. 30 Panama ...problem location discussed in this report is at St. Andrew Bay near Panama City, Florida. A relatively short section of the jettied inlet channel requires

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

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

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

  19. Short-term impact of deep sand extraction and ecosystem-based landscaping on macrozoobenthos and sediment characteristics.

    PubMed

    de Jong, Maarten F; Baptist, Martin J; Lindeboom, Han J; Hoekstra, Piet

    2015-08-15

    We studied short-term changes in macrozoobenthos in a 20m deep borrow pit. A boxcorer was used to sample macrobenthic infauna and a bottom sledge was used to sample macrobenthic epifauna. Sediment characteristics were determined from the boxcore samples, bed shear stress and near-bed salinity were estimated with a hydrodynamic model. Two years after the cessation of sand extraction, macrozoobenthic biomass increased fivefold in the deepest areas. Species composition changed significantly and white furrow shell (Abra alba) became abundant. Several sediment characteristics also changed significantly in the deepest parts. Macrozoobenthic species composition and biomass significantly correlated with time after cessation of sand extraction, sediment and hydrographical characteristics. Ecosystem-based landscaped sand bars were found to be effective in influencing sediment characteristics and macrozoobenthic assemblage. Significant changes in epifauna occurred in deepest parts in 2012 which coincided with the highest sedimentation rate. We recommend continuing monitoring to investigate medium and long-term impacts.

  20. Bed Bug Clearinghouse by Topic

    EPA Pesticide Factsheets

    This information is intended to help states, communities, and consumers prevent and control bed bug infestations. Topics include bed bug biology and behavior, detection and monitoring, non-chemical techniques such as heat treatment, and pesticides.

  1. Factors controlling the size and shape of stream channels in coarse noncohesive sands

    USGS Publications Warehouse

    Wolman, M. Gordon; Brush, Lucien M.

    1961-01-01

    The size and shape of equilibrium channels in uniform, noncohesive sands, 0.67 mm and 2.0 mm in diameter, were studied experimentally in a laboratory flume 52 feet long in which discharge, slope, sediment load, and bed and bank material could be varied independently. For each run a straight trapezoidal channel was molded in the sand and the flume set at a predetermined slope. Introduction of the discharge was accompanied by widening and aggradation until a stable channel was established. By definition a stable equilibrium existed when channel width, water surface slope, and rate of transport became constant. The duration of individual runs ranged from 2 to 52 hours depending upon the time required for establishing equilibrium. Stability of the banks determined channel shape. In the 2.0 mm sand at a given slope and discharge, only one depth was stable. At this depth the flow was just competent to move particles along the bed of the channel. An increase in discharge produced a wider channel of the same depth and thus transport per unit width remained at a minimum. Channels in the 0.67 mm sand were somewhat more stable and permitted a 1.5 fold increase in depth above that required to start movement of the bed material. An increased transport was associated with the increase in depth. The rate of transport is adequately described in terms of the total shear or in terms of the difference between the total shear and the critical shear required to begin movement. In these experiments the finer, or 0.67 mm, sand, began to move along the bed of the channel at a constant shear stress. Incipient movement of the coarser, or 2.0 mm, sand, varied with the shear stress as well as the mean velocity. At the initiation of movement a lower shear was associated with a higher velocity and vice versa. Anabranches of braided rivers and some natural river channels formed in relatively noncohesive materials resemble the essential characteristics of the flume channels. For a given slope and

  2. Stochastic analysis of particle movement over a dune bed

    USGS Publications Warehouse

    Lee, Baum K.; Jobson, Harvey E.

    1977-01-01

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

  3. Direct combustion of olive cake using fluidized bed combustor

    SciTech Connect

    Khraisha, Y.H.; Hamdan, M.A.; Qalalweh, H.S.

    1999-05-01

    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.

  4. Cyclicity concept in a deltaic to shallow-marine environment of deposition concerning an oil-sand setting

    SciTech Connect

    Rodriguez, A.

    1984-04-01

    The need to accurately define sand trend and quality in a deltaic to shallow-marine environment of deposition where facies changes take place over a short distance is widely recognized. In an oil-sand environment, such as the Cerro Negro area of the Orinoco Petroliferous Belt, this need is more evident because enhanced recovery projects are necessary. Facies variability and correlation problems in such a setting have led many workers to apply indiscriminately the cyclicity concept as an exploration/exploitation tool. According to this concept, a cycle begins with a transgressive sand and ends with a marsh facies represented by a coal bed. Subdivision of the rock column into cycles allow delineation of sand geometry. Recent works have demonstrated that rooted coal beds can be formed in different coastal environments, ranging from the upper delta plain to the back-barrier lagoon facies. Therefore, it is obvious that the association of these facies will differ from one another and from the standard cycle concept. In the Cerro Negro area, the process-controlled genetic unit concept was of great help in defining sand geometry and quality. The rock column of cored wells can be subdivided according to the presence of physical and biological parameters into 4 units, differentiated by the occurrence of rooted coal, limestone, sand, shale, Ophiomorpha-type burrows (Fositextura figurativa), bioturbation structures (Fositextura deformativa), and shell fragments.

  5. Holocene stratigraphy of the Alabama inner continental shelf: Influence of shelf sand ridges on determining lithofacies architecture

    SciTech Connect

    Davies, D.J.; Parker, S.J. . Energy and Coastal Geology Div.)

    1993-03-01

    Surface and subsurface distribution of lithofacies from Holocene sediments of the AL inner continental shelf was determined from a series of 59 vibracores and associated surface sediment grab sediments. Five Holocene lithofacies composed of 12 discrete microfacies were delineated based on grain size, color, sedimentary structures, shell content, and fabric of samples. These lithofacies include: (1) Graded Shelly Sand Lithofacies; (2) Clean Sand Lithofacies; (3) Dirty Sand Lithofacies; (4) Biogenic Sediment Lithofacies; and (5) Muddy Sediment Lithofacies. These represent four major depositional environments: The Shelf Sand Sheet Environment (lithofacies 1 and 2); the Sand Ridge Environment (lithofacies 1, 2, and 3); the Bay/Lagoon Environment (lithofacies 3, 4 and 5); and the Muddy Shelf Environment (lithofacies 5). East of the Main Pass of Mobile Bay, the seafloor is composed of a clean Shelf Sand Sheet with oblique shelf sand ridges; Clean Sand and Graded Shelly Sand are the dominant surface sediment types. Coarse shell beds that grade up to quartz sand units (total thickness 0.1 to 3+m) interpreted as tempestites comprise most of the upper portion of the ridges. West of the Pass, the muddier lithofacies (3 and 5) dominate surface samples. Microfacies at depth represent the early Holocene transgressive systems tract; these include the Muddy Shelf Depositional Environment and the filled estuaries and bays of the flooded Pleistocene fluvial valleys represented by the Bay/Lagoon Depositional Environment. The AL inner shelf provides an excellent model of the variability of sedimentation mode in time and space during deposition of a transgressive systems tract. Development of the palimpsest sand sheet/ridge complex progressed on the eastern shelf due to shut off of sediment influx, westward longshore currents, and episodic incidence of major hurricanes. On the western shelf a patchy distribution of muddier sediments developed from input of floodwaters from Mobile Bay.

  6. Petroleum geology of East Dykesville field, Smackover C sand, Claiborne and Webster Parishes, Louisiana

    SciTech Connect

    Sartor, C.L.; Howard, S.R.

    1984-09-01

    The discovery in 1980 of gas production in the Smackover C sand in the East Dykesville field of Claiborne and Webster Parishes, Louisiana, extended the productive limits of this reservoir 6 mi (10 km) south of the production in the Haynesville field. The development of East Dykesville field has revealed three productive fault blocks within an area 6 mi (10 km) by 3 mi (5 km). The Smackover C and B sand of East Dykesville are present 700 ft (213 m) above the Louann Salt as a portion of a more or less continuous sand body covering an area 9 mi (15 km) from east to west. This sand body extends southward from the Arkansas-Louisiana state line for more than 10 mi (16 km), and also produces at the Haynesville field. Production has been encountered in the C sand at East Dykesville from 10,912 ft (3326 m) subsea down to 11,605 ft (3536 m) subsea, an interval of 693 ft (211 m). The source of the sediments which constitute the Smackover C sand appears to be north of the sand body, as it thickens to more than 100 ft (31 m) in the Red Rock-Haynesville area and thins southward. The sand also thins both to the east toward Haynesville and to the west toward Shongaloo. The C sand is 60 ft (18 m) thick in the north portion of East Dykesville field and thins to 20 ft (6 m) in the most southern wells. Isopach studies suggest a submarine-fan depositional environment on a stable shelf.

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

    USGS Publications Warehouse

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

    2011-01-01

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

  8. Enhanced stability of steep channel beds to mass failure and debris flow initiation

    NASA Astrophysics Data System (ADS)

    Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

    2015-12-01

    Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

  9. METHOD OF PROCESSING MONAZITE SAND

    DOEpatents

    Welt, M.A.; Smutz, M.

    1958-08-26

    A process is described for recovering thorium, uranium, and rare earth values from monazite sand. The monazite sand is first digested with sulfuric acid and the resulting "monazite sulfate" solution is adjusted to a pH of between 0.4 and 3.0, and oxalate anions are added causing precipitation of the thorium and the rare earths as the oxalates. The oxalate precipitate is separated from the uranium containing supernatant solution, and is dried and calcined to the oxides. The thorium and rare earth oxides are then dissolved in nitric acid and the solution is contacted with tribntyl phosphate whereby an organic extract phase containing the cerium and thorium values is obtained, together with an aqueous raffinate containing the other rare earth values. The organic phase is then separated from the aqueous raffinate and the cerium and thorium are back extracted with an aqueous medium.

  10. Reservoir evaluation of thin-bedded turbidites and hydrocarbon pore thickness estimation for an accurate quantification of resource

    NASA Astrophysics Data System (ADS)

    Omoniyi, Bayonle; Stow, Dorrik

    2016-04-01

    One of the major challenges in the assessment of and production from turbidite reservoirs is to take full account of thin and medium-bedded turbidites (<10cm and <30cm respectively). Although such thinner, low-pay sands may comprise a significant proportion of the reservoir succession, they can go unnoticed by conventional analysis and so negatively impact on reserve estimation, particularly in fields producing from prolific thick-bedded turbidite reservoirs. Field development plans often take little note of such thin beds, which are therefore bypassed by mainstream production. In fact, the trapped and bypassed fluids can be vital where maximising field value and optimising production are key business drivers. We have studied in detail, a succession of thin-bedded turbidites associated with thicker-bedded reservoir facies in the North Brae Field, UKCS, using a combination of conventional logs and cores to assess the significance of thin-bedded turbidites in computing hydrocarbon pore thickness (HPT). This quantity, being an indirect measure of thickness, is critical for an accurate estimation of original-oil-in-place (OOIP). By using a combination of conventional and unconventional logging analysis techniques, we obtain three different results for the reservoir intervals studied. These results include estimated net sand thickness, average sand thickness, and their distribution trend within a 3D structural grid. The net sand thickness varies from 205 to 380 ft, and HPT ranges from 21.53 to 39.90 ft. We observe that an integrated approach (neutron-density cross plots conditioned to cores) to HPT quantification reduces the associated uncertainties significantly, resulting in estimation of 96% of actual HPT. Further work will focus on assessing the 3D dynamic connectivity of the low-pay sands with the surrounding thick-bedded turbidite facies.

  11. Thermal Properties of oil sand

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  12. Offshore sand and gravel mining

    SciTech Connect

    Pandan, J.W.

    1983-05-01

    This paper reviews the status of mining offshore for sand and gravel on a world-wide basis. It discusses the technology for exploration and evaluation of sea floor mineral targets, as well as mining, transportation, and processing. Large operations in Japan and Europe are described, based upon personal observations of the author. The U.S. situation is outlined and opinions offered as to the outlook for the future.

  13. High-temperature sand consolidation

    SciTech Connect

    Friedman, R.H.; Suries, B.W.; Kleke, D.E.

    1987-05-01

    A sand consolidation system has been developed that is stable to wellbore temperatures of 700/sup 0/F (371/sup 0/C). Two improvements in technique have contributed to this development. First, a controlled quantity of catalyst is absorbed on the sand. Consequently, consolidation occurs only on or very near the sand grains, resulting in a high-permeability consolidation. Second, the reaction is driven to completion by avoiding, insofar as possible, the adverse effect of water. The resin used for the consolidation is a very viscous derivative of furfuryl alcohol that requires a diluent to make it injectable. The diulent used to reduce viscosity is a hydrolyzable ester. The diluted fluid, which is sill more viscous than water, displaces much of the water present in the pore space. During the catalyzed consolidation, water produced by the polymerization is removed by reaction with the diluent (hydrolysis of the ester). The high-molecular-weight polymeric consolidation is better able to resist the high temperatures encountered in steam-displacement producing wells. Adaptation of the technology has been made so that the process can also be used in low-temperature wells. Because of the catalysis method, long shelf life is guaranteed for the consolidating formation.

  14. Debris-bed friction of hard-bedded glaciers

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

    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.

  15. Debris-Bed Friction of Hard-Bedded Glaciers

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    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.

  16. Fluidized-bed combustion

    SciTech Connect

    Botros, P E

    1990-04-01

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

  17. Cardiovascular consequences of bed rest: effect on maximal oxygen uptake

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.

    1997-01-01

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

  18. Fluidized-bed boilers

    SciTech Connect

    Makansi, J.; Schwieger, B.

    1982-08-01

    Discusses atmospheric fluidized-bed (AFB) boilers with regard to designs available, manufacturers involved, and operating experience. Proven fuel flexibility and satisfactory SO/sub 2/ control without scrubbers make AFB boilers a viable option for industrial steam generation worldwide. Technical concepts on which AFB application is based are a departure from the more familiar methods of burning solid fuels. Behind US thrust for AFB development is the need to burn coal within pollution regulations.

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

    PubMed

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

    2011-04-01

    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

  20. Combustion behaviours of tobacco stem in a thermogravimetric analyser and a pilot-scale fluidized bed reactor.

    PubMed

    Yang, Zixu; Zhang, Shihong; Liu, Lei; Li, Xiangpeng; Chen, Hanping; Yang, Haiping; Wang, Xianhua

    2012-04-01

    Despite its abundant supply, tobacco stem has not been exploited as an energy source in large scale. This study investigates the combustion behaviours of tobacco stem in a thermogravimetric analyser (TGA) and a pilot-scale fluidized bed (FB). Combustion characteristics, including ignition and burnout index, and combustion reaction kinetics were studied. Experiments in the FB investigated the effects of different operating conditions, such as primary air flow, secondary air flow and feeding rates, on the bed temperature profiles and combustion efficiency. Two kinds of bed materials cinder and silica sand were used in FB and the effect of bed materials on agglomeration was studied. The results indicated that tobacco stem combustion worked well in the FB. When operation condition was properly set, the tobacco stem combustion efficiency reached 94%. In addition, compared to silica sand, cinder could inhibit agglomeration during combustion because of its high aluminium content.

  1. Combustion in fluidized beds

    SciTech Connect

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

    1990-07-01

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

  2. Sand Sheet on Crater Floor

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

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

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

    Image information: VIS instrument. Latitude 26.4, Longitude 62.7 East (297.3 West). 19 meter/pixel resolution.

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

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

  3. Using high-resolution suspended-sediment measurements to infer changes in the topographic distribution and grain size of bed sediment in the Colorado River downstream from Glen Canyon Dam

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    Eddy sandbars and other sandy deposits in and along the Colorado River in Grand Canyon National Park (GCNP) were an integral part of the pre-dam riverscape, and are still important for habitat, protection of archeological sites, and recreation. Recent work has shown that eddy bars are dynamic landforms and represent the bulk of the ecosystem's sand reserves. These deposits began eroding following the 1963 closure of Glen Canyon Dam that reduced the supply of sand at the upstream boundary of GCNP by about 94% and are still eroding today. Sand transport in the post-dam river is limited by episodic resupply from tributaries, and is equally regulated by the discharge of water and short-term changes in the grain size of sand available for transport (Rubin and Topping, WRR, 2001). 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. This prohibits the computation of sand-transport rates in the Colorado River using stable relations between water discharge and sand transport (i.e., sediment rating curves) and requires a more continuous method for measuring sand transport. To monitor suspended sediment at higher (i.e., 15-minute) resolutions, we began testing a laser-acoustic system at four locations along the Colorado River in Grand Canyon in August 2002. Because they are much easier to acquire, the high-resolution suspended-sediment datasets collected using the laser-acoustic systems greatly outnumber (by >5 orders of magnitude) direct grain-size measurements of the upstream bed sediment. Furthermore, suspension processes effectively provide an average "sample" of the bed sediment on the perimeter of the upstream channel and the underwater portions of the banks and

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    Experiments are investigating the behavior of individual sand grains in the high-energy martian aeolian regime. Energy partitioning during impact of a saltating grain determines grain longevity, but it also influences the way in which the bed becomes mobilized by reptation. When single grains of sand are fired into loose beds, the bed can absorb up to 90% of the impact energy by momentum transfer to other grains; it has been discovered that the impacting grains cause circular craters even at low impact angles. Hundreds of grains can be splashed by a single high-velocity (100 m/s) impact causing more bed disturbance through reptation than previously thought. The research is supported by NASA's PG&G Program. Because the martian aeolian environment in both high energy and of long duration, the most mobile fractions of windblown sand should have eradicated themselves by attrition, unless sand supply has kept pace with destruction. It is therefore important to understand the rate of grain attrition in order to make sense of the existence of vast dune fields on Mars. Attrition, has been addressed in other studies, but precise data for a single saltating grain striking a loose bed of sand have not been acquired -- the quintessential case to be understood for dunes on Mars. To acquire these data, we are employing a compound crossbow which has the bolt-firing mechanism replaced with a pneumatically-automated sabot system. The sabot can launch individual grains of sand of any size between several millimeters and about 50 microns, at velocities up to 100m/s. This is around the maximum velocity expected for saltating grains on Mars. The sabot sled is equipped with photoelectric sensors for measuring shot velocity. Baffling of the grain's exit orifice has enabled projection of single grains without significant aerodynamic effects from the sabot. Grains are fired into loose beds of sand at about 15 degrees from the horizontal (typical saltation trajectory at impact) while being

  5. DCS of Syrtis Major Sand Migration

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

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

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

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

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

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  7. Computational fluid-dynamics modeling of the hydrodynamics of fluidization in the sand surrounding a lost-foam casting pattern

    NASA Astrophysics Data System (ADS)

    Hudson, Nathanael; Bhavnani, Sushil H.; Overfelt, Ruel A.

    2002-08-01

    In many modern industries, complex shapes arise which require advanced metal casting processes to produce a component. The problem with these cast parts is the empiricism required to develop the casting process and the accompanying time and expense involved. There has been interest in using a fluidized bed to allow molding sand to better encapsulate the complicated surface geometries of lost-foam patterns. Fluidization, coupled with a single mixing jet of much greater magnitude than the minimum fluidization velocity, helps to homogenize the sand through stirring and may improve the integrity of the casting. At the bottom of the bed is an array of fluidizing jets distributed through a porous plate, which maintain the bed at minimum fluidization. Superimposed upon these smaller jets is a large mixing jet, which serves to mix and homogenize the sand. At issue is the hydrodynamics of the sand and air surrounding the foam pattern. The PHOENICS commercial software package was amended to simulate the flow around the precasting foam geometry. Employing a two-fluid approach, each phase was considered a fluid that interpenetrates the other phase. The modification required that the kinetic theory of granular flow for the sand phase be incorporated into the recompilable PHOENICS code. The results of this study consisted of time-averaged voidage patterns, with voidage being defined as the volume fraction of air in the mixture, around the foam pattern submerged in a two-dimensional fluidized bed. The model was benchmarked against fluidized-bed experiments performed by previous investigators. In order to elucidate the dependence of the voidage around the lost-foam pattern, selected physical parameters were varied, and the resultant void-fraction maps were predicted with the model. Physical parameters such as the aspect ratio of the width to length of the foam pattern, the placement of the mixing jet, and different mixing-jet velocities were varied to illustrate the dependence of

  8. Compressive strength of dune sand reinforced concrete

    NASA Astrophysics Data System (ADS)

    Mohammed, Mani; Abdelouahed, Kriker; Allaoua, Belferrag

    2017-02-01

    Many areas of south Algeria suffer from the problem of accumulation of sand on constructions. In fact, the phenomenon of sand silting causes technical and economical problems. Besides, these areas and other regions in Algeria suffer from the problem of unavailability of suitable sand for building. The use of dune sand offers an alternative solution for construction. In the same context, many researches confirm the possibility of using dune sand in the composition of concrete. In this paper, concrete made with dune sand was studied. For correction of the granulometry of dune sand by river sand, the rates of 50% DS+50% RS and 40% DS+60% RS were used. Also, two types of fibers were used, with 45 and 30 mm lengths, and diameters of 1 and 0.5 mm respectively. The percentage of the used fibers in the sand concrete was 1% and 1.5%. In this work an improvement of the compressive strength for the metal fibers reinforced sand concrete compared to plain concrete was obtained.

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

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

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

  10. Seeing Red

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

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

    The red color of the Tvashtar plume fallout is typical of Io's largest volcanic plumes, including the previous eruption of Tvashtar seen by the Galileo and Cassini spacecraft in 2000, and the long-lived Pele plume on the opposite side of Io. The color likely results from the creation of reddish three-atom and four-atom sulfur molecules (S3 and S4) from plume gases rich in two-atom sulfur molecules (S2 After a few months or years, the S3 and S4 molecules recombine into the more stable and familiar yellowish form of sulfur consisting of eight-atom molecules (S8), so these red deposits are only seen around recently-active Io

  11. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    USGS Publications Warehouse

    Remo, Jonathan; Heine, Ruben A.; Ickes, Brian

    2016-01-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  12. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    NASA Astrophysics Data System (ADS)

    Remo, Jonathan W. F.; Heine, Reuben A.; Ickes, Brian S.

    2016-07-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  13. Interpreting Hydraulic Conditions from Morphology, Sedimentology, and Grain Size of Sand Bars in the Colorado River in Grand Canyon

    NASA Astrophysics Data System (ADS)

    Rubin, D. M.; Topping, D. J.; Schmidt, J. C.; Grams, P. E.; Buscombe, D.; East, A. E.; Wright, S. A.

    2015-12-01

    During three decades of research on sand bars and sediment transport in the Colorado River in Grand Canyon, we have collected unprecedented quantities of data on bar morphology, sedimentary structures, grain size of sand on the riverbed (~40,000 measurements), grain size of sand in flood deposits (dozens of vertical grain-size profiles), and time series of suspended sediment concentration and grain size (more than 3 million measurements using acoustic and laser-diffraction instruments sampling every 15 minutes at several locations). These data, which include measurements of flow and suspended sediment as well as sediment within the deposits, show that grain size within flood deposits generally coarsens or fines proportionally to the grain size of sediment that was in suspension when the beds were deposited. The inverse problem of calculating changing flow conditions from a vertical profile of grain size within a deposit is difficult because at least two processes can cause similar changes. For example, upward coarsening in a deposit can result from either an increase in discharge of the flow (causing coarser sand to be transported to the depositional site), or from winnowing of the upstream supply of sand (causing suspended sand to coarsen because a greater proportion of the bed that is supplying sediment is covered with coarse grains). These two processes can be easy to distinguish where suspended-sediment observations are available: flow-regulated changes cause concentration and grain size of sand in suspension to be positively correlated, whereas changes in supply can cause concentration and grain size of sand in suspension to be negatively correlated. The latter case (supply regulation) is more typical of flood deposits in Grand Canyon.

  14. The Dark Surfaces of Mars: Mantles and Sand Sheets

    NASA Technical Reports Server (NTRS)

    2000-01-01

    accumulations of windblown sand.

    The first two pictures presented here (A and B, above) show dark, blanketed or mantled surfaces in the Sinus Sabaeus region (310o-350o W longitude and 5o-12oS latitude) of Mars. This dark material in some places has bright dunes on top of it (top, left picture), and in other places appears to have narrow cracks running through it (top, right picture). If the dark material consisted of sand, it would show drifts and tails formed around and behind obstacles as are seen in the thick sand sheets of Ganges Chasma (C and D, above). Because wind transports sand close to the ground, it interacts with obstacles such as the bright mounds in Figure C (above) to make drifts and tails.

    The top left picture is MOC image AB1-11105 located in Sinus Sabaeus near 7.0oS, 343.4oW. The top right picture is also in Sinus Sabaeus and is MOC image M00-01078 near 10.0oS, 329.1oW. The bottom left pair of images show a thick sheet of dark sand in Ganges Chasma. The bottom right picture is a stereo anaglyph (use 3-d red/blue glasses) MOC wide angle view showing the locations of the two Ganges Chasma images. Ganges Chasma is around 7oS, 50oW. All pictures are illuminated from the left. The AB1 images were taken in January 1998, the M00 images are from April 1999.

  15. Coal Bed Methane Primer

    SciTech Connect

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  16. Bed Rest Muscular Atrophy

    NASA Technical Reports Server (NTRS)

    Greenleaf, John E.

    2000-01-01

    A major debilitating response from prolonged bed rest (BR) is muscle atrophy, defined as a "decrease in size of a part of tissue after full development has been attained: a wasting away of tissue as from disuse, old age, injury or disease". Part of the complicated mechanism for the dizziness, increased body instability, and exaggerated gait in patients who arise immediately after BR may be a result of not only foot pain, but also of muscular atrophy and associated reduction in lower limb strength. Also, there seems to be a close association between muscle atrophy and bone atrophy. A discussion of many facets of the total BR homeostatic syndrome has been published. The old adage that use determines form which promotes function of bone (Wolff's law) also applies to those people exposed to prolonged BR (without exercise training) in whom muscle atrophy is a consistent finding. An extreme case involved a 16-year-old boy who was ordered to bed by his mother in 1932: after 50 years in bed he had "a lily-white frame with limbs as thin as the legs of a ladder-back chair". These findings emphasize the close relationship between muscle atrophy and bone atrophy. In addition to loss of muscle mass during deconditioning, there is a significant loss of muscle strength and a decrease in protein synthesis. Because the decreases in force (strength) are proportionately greater than those in fiber size or muscle cross-sectional area, other contributory factors must be involved; muscle fiber dehydration may be important.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  18. Performance of a sand filter in removal of micro-algae from seawater in aquaculture production systems.

    PubMed

    Sabiri, N E; Castaing, J B; Massé, A; Jaouen, P

    2012-01-01

    In this study, a sand filter was used to remove micro-algae from seawater feeding aquaculture ponds. A lab-scale sand filter was used to filter 30,000 cells/mL of Heterocapsa triquetra suspension, a non-toxic micro-alga that has morphological and dimensional (15-20 microm) similarities with Alexandrium sp., one of the smallest toxic micro-algae in seawater. Removal efficiency and capture mechanisms for a fixed superficial velocity (3.5 m/h) were evaluated in relation to size distribution and mean diameter of the sand. Various sands (average diameter ranging between 200 microm and 600 microm) were characterized and used as porous media. The structural parameters of the fixed beds were evaluated for each medium using experimental measurements of pressure drop as a function of superficial velocity over a range of Reynolds numbers covering Darcy's regime and the inertial regime. For a filtration cycle of six hours, the best efficiency (E = 90%) was obtained with the following sand characteristics: sieved sand with a range of grain diameter of 100 and 300 microm and a mean grain diameter equal to 256 microm. Results obtained show the influence of the size distribution of sand on the quality of retention of the micro-algae studied.

  19. Method and device for sand control

    SciTech Connect

    Best, D.A.; Grondin, K.C.

    1992-03-17

    This patent describes a single walled sand control device for use in a well. It comprises a single liner containing at least one slot that penetrates that liner and extends radially or axially therein which slot has a berm along each of its sides thereby causing a bridging of sand grains across the slot which results in substantially better sand control. This patent also describes a method for removing sand from hydrocarbonaceous fluids produced to the surface via a well. It comprises placing a single walled liner on the end of a tube used to produce hydrocarbonaceous fluids to the surface from a formation; cutting at least one slot through the liner which extends radially or axially therein; forming a berm along each side of the slot which causes a sand bridge to form across sail slot thereby removing substantially more sand from produced hydrocarbonaceous fluid.

  20. Fluidized-bed sorbents

    SciTech Connect

    Gangwal, S.K.; Gupta, R.P.

    1994-10-01

    The objectives of this project are to identify and demonstrate methods for enhancing long-term chemical reactivity and attrition resistance of zinc oxide-based mixed metal-oxide sorbents for desulfurization of hot coal-derived gases in a high-temperature, high-pressure (HTHP) fluidized-bed reactor. In this program, regenerable ZnO-based mixed metal-oxide sorbents are being developed and tested. These include zinc ferrite, zinc titanate, and Z-SORB sorbents. The Z-SORB sorbent is a proprietary sorbent developed by Phillips Petroleum Company (PPCo).

  1. Biparticle fluidized bed reactor

    DOEpatents

    Scott, C.D.; Marasco, J.A.

    1996-02-27

    A fluidized bed reactor system is described which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary and tertiary particulate phases, continuously introduced and removed simultaneously in the cocurrent and countercurrent mode, act in a role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Means for introducing and removing the sorbent phases include feed screw mechanisms and multivane slurry valves. 3 figs.

  2. Biparticle fluidized bed reactor

    DOEpatents

    Scott, C.D.; Marasco, J.A.

    1995-04-25

    A fluidized bed reactor system utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves. 3 figs.

  3. Biparticle fluidized bed reactor

    DOEpatents

    Scott, Charles D.

    1993-01-01

    A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves.

  4. Biparticle fluidized bed reactor

    DOEpatents

    Scott, Charles D.; Marasco, Joseph A.

    1996-01-01

    A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary and tertiary particulate phases, continuously introduced and removed simultaneously in the cocurrent and countercurrent mode, act in a role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Means for introducing and removing the sorbent phases include feed screw mechanisms and multivane slurry valves.

  5. Biparticle fluidized bed reactor

    DOEpatents

    Scott, Charles D.; Marasco, Joseph A.

    1995-01-01

    A fluidized bed reactor system utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves.

  6. Biparticle fluidized bed reactor

    DOEpatents

    Scott, C.D.

    1993-12-14

    A fluidized bed reactor system which utilizes a fluid phase, a retained fluidized primary particulate phase, and a migratory second particulate phase is described. The primary particulate phase is a particle such as a gel bead containing an immobilized biocatalyst. The secondary particulate phase, continuously introduced and removed in either cocurrent or countercurrent mode, acts in a secondary role such as a sorbent to continuously remove a product or by-product constituent from the fluid phase. Introduction and removal of the sorbent phase is accomplished through the use of feed screw mechanisms and multivane slurry valves. 3 figures.

  7. Particle bed reactor modeling

    NASA Technical Reports Server (NTRS)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    1993-01-01

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  8. Bed drain cover assembly for a fluidized bed

    DOEpatents

    Comparato, Joseph R.; Jacobs, Martin

    1982-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Nittrouer, Jeffrey A.; Viparelli, Enrica

    2014-05-01

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

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

    PubMed

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

    2014-04-30

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

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

    SciTech Connect

    Kolb, M.M.; Parks, S.L. )

    1991-02-01

    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.

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

    PubMed

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

    2013-11-01

    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.

  13. Iron crystallization in a fluidized-bed Fenton process.

    PubMed

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

    2011-05-01

    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.

  14. Wind-blown sand on beaches: an evaluation of models

    NASA Astrophysics Data System (ADS)

    Sherman, Douglas J.; Jackson, Derek W. T.; Namikas, Steven L.; Wang, Jinkang

    1998-03-01

    for the effects of slope and moisture content were calculated using the models of Bagnold [Bagnold, R.A., 1973. The nature of saltation and 'bed-load' transport in water. Proc. R. Soc. London, Ser. A, 332, 473-504] and Belly [Belly, P.-Y., 1964. Sand movement by wind. U.S. Army Corps Eng. CERC. Tech. Mem. 1, Washington D.C., 38 pp.], respectively. None of the models was able to produce a strong correspondence between measured and predicted rates of transport. Best results were obtained using the Bagnold and Zingg models, and the Kadib model was the least viable of this group. The influence of sediment moisture content appeared to be the critical factor in degrading model viability. Overall, none of the models is adequate for general applications to coastal-aeolian environments where moisture content complications tend to override the predictive competence of the simple transport formulations.

  15. Tidal River Elbe - a sediment budget for the grain size fraction of medium sand

    NASA Astrophysics Data System (ADS)

    Winterscheid, Axel

    2016-04-01

    marine clay by capital dredging, Weichselion sandy deposits, which formed the geological layer underneath, now became part of the sediment transport regime. Nowadays, most sections of the main channel are morphologically characterized by a medium sandy river bed and subaquatic dunes of several meters height followed by sections of a poorly structured river bed caused by the sedimentation of silty sediments. By setting up the sediment balance for medium sand, the fluxes entering the estuary from the inland Elbe is one source term in the equation. The average annual load for the medium sand is estimated to be 110,000 m³/year (1996 - 2008, measurement station Neu Darchau). Further downstream in the tidal part of the river there are no further measurement stations located, but the analysis of a time series of multibeam sonar data (2000 to 2014) shows that large amounts of medium sand episodically pass the tidal weir at Geesthacht only in the event of extreme flood. This is due to a significant increase in bed volume between Geesthacht and the Port of Hamburg in the aftermath of a singular extreme event. Until the next extreme event the bed volume (functions as temporary storage for medium sand) is eroding again, which is the second source term. By comparing the information on bed load fluxes, the evolution of bed volumes over time and the dredging statistics we can conclude for the longer term that the total amount of medium sand that has been dredged and taken out of the system for constructional purposes is the same order of magnitude compared to the sum of both source terms. Hence, there is no or very limited net transport of medium sand passing the port area and entering the downstream river section. From the subsequent analysis of multibeam sonar data (2008 - 2014) we know for the river section from Hamburg to Brunsbuettel (total distance of 40 km) that there has been a continuous loss of about 1 Mio. m³/a in bed volumes, which means a deficit situation for medium

  16. A branching process model for sand avalanches

    SciTech Connect

    Garcia-Pelayo, R.; Salazar, I.; Schieve, W.C. )

    1993-07-01

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

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

    USGS Publications Warehouse

    Wiele, S.M.

    1998-01-01

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

  18. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

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

  19. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

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

  20. Fast fluidized bed steam generator

    DOEpatents

    Bryers, Richard W.; Taylor, Thomas E.

    1980-01-01

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

  1. Sand control agent and process

    SciTech Connect

    Shu, P.; Strom, E.T.; Donlon, W.P.

    1993-06-29

    A method is described for forming a consolidated gravel pack in a washed-out interval adjacent to a borehole in an unconsolidated or loosely consolidated formation comprising: (a) perforating a cased borehole at an interval of the formation having a washed-out interval adjacent said borehole; (b) placing sand into said washed-out interval via perforations in the borehole; (c) injecting an aqueous silicate solution into said interval through perforations contained in the borehole which silicate is of a strength sufficient to react with a water-miscible organic solvent containing an alkylpolysilicate and a member of the group consisting of an inorganic salt, organic salt, or chelated calcium thereby forming a permeability retentive cement where said aqueous silicate is selected from a member of the group consisting of alkali metal silicate, organoammonium silicate, or ammonium silicate; (d) injecting next a spacer volume of water-immiscible hydrocarbonaceous liquid into said zone; and (e) injecting thereafter a water-miscible organic solvent containing an alkylpolysilicate and said group member into said interval in an amount sufficient to react with the aqueous silicate so as to form a silicate cement with permeability retentive characteristics whereupon the interval is consolidated in a manner sufficient to form a gravel pack thereby preventing sand from being produced from the formation during the production of hydrocarbonaceous fluids.

  2. Laboratory measurement of saltating sand particles' angular velocities and simulation of its effect on saltation trajectory

    NASA Astrophysics Data System (ADS)

    Xie, Li; Ling, Yuquan; Zheng, Xiaojing

    2007-06-01

    This paper reports a laboratory observation of spin attitudes and angular velocities of saltating sand particles in wind-blown sand flux by using the high-speed and dynamic cinecamera and presents a numerical simulation to show the effect of spin on the saltating trajectories of sand particles. Experiment results show that a saltating sand particle has two basic spin attitudes, rolling spin (Ωx, which is perpendicularity to wind direction and parallel with sand surface) and left/right spin. The percentages of the former and the latter attitude are 5% and 95%, respectively. The left/right spin angular velocities range from 0 revolutions per second ("rev/s" henceforth) to 800 rev/s and obey a single-peaked distribution, the peak value of which lies in (150 rev/s, 250 rev/s). The rolling spin angular velocity of a saltation sand particle is variational along its entire saltating trajectory. The left/right spin vector is composed of two spin components, Ωy (called lateral spin component, rotating around the wind direction) and Ωz (called up spin component, rotating around the axis perpendicular to the sand bed). The theoretical simulation indicates that lateral and up spin components not only have effects on the trajectories' scales (i.e., heights and lengths) but also have effects on the trajectories' dimensions, especially when they are higher than 2000 rev/s and 200 rev/s, respectively. While the rolling spin angular velocities only change the trajectories' heights and lengths, especially for the rolling angular velocity higher than 300 rev/s.

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

    USGS Publications Warehouse

    Adams, P.N.; Ruggiero, P.; Schoch, G.C.; Gelfenbaum, G.

    2007-01-01

    Using a digital video-based Argus Beach Monitoring System (ABMS) on the north shore of Kachemak Bay in south central Alaska, we document the timing and magnitude of alongshore migration of intertidal sand bed forms over a cobble substrate during a 22-month observation period. Two separate sediment packages (sand bodies) of 1-2 m amplitude and ???200 m wavelength, consisting of well-sorted sand, were observed to travel along shore at annually averaged rates of 278 m/yr (0.76 m/d) and 250 m/ yr (0.68 m/d), respectively. Strong seasonality in migration rates was shown by the contrast of rapid winter and slow summer transport. Though set in a megatidal environment, data indicate that sand body migration is driven by eastward propagating wind waves as opposed to net westward directed tidal currents. Greatest weekly averaged rates of movement, exceeding 6 m/d, coincided with wave heights exceeding 2 m suggesting a correlation of wave height and sand body migration. Because Kachemak Bay is partially enclosed, waves responsible for sediment entrainment and transport are locally generated by winds that blow across lower Cook Inlet from the southwest, the direction of greatest fetch. Our estimates of sand body migration translate to a littoral transport rate between 4,400-6,300 m3/yr. Assuming an enclosed littoral cell, minimal riverine sediment contributions, and a sea cliff sedimentary fraction of 0.05, we estimate long-term local sea cliff retreat rates of 9-14 cm/yr. Applying a numerical model of wave energy dissipation to the temporally variable beach morphology suggests that sand bodies are responsible for enhancing wave energy dissipation by ???13% offering protection from sea cliff retreat. Copyright 2007 by the American Geophysical Union.

  4. The suitability of sand abstraction systems for community-managed domestic water supplies.

    PubMed

    Hussey, S W

    2000-01-01

    This paper will discuss the system of abstracting water from the underlying water-bearing sediment of surface dry river beds. The technology is well established in Zimbabwe and is a valuable method of obtaining water for human consumption as well as for both livestock and irrigation use. Within Zimbabwe the system is erroneously but commonly, referred to as "sand abstraction". Apart from traditional methods there are several systems of sand abstraction which have been developed. Each method is dependant on equipment which can be installed into river sands which retain water. Systems range from large mechanized schemes to small scale, hand-operated pump and well screen units. The author, through his work and experience in this area has come to believe that small scale units which can be operated and sustained by local communities are the best option for reliable sources of clean water. In large rivers the sediment frequently retains a perennial supply of water and during a dry-season can provide many thousands of kilolitres of water. The river sands act as a huge, slow sand-filtration system and invariably yield water which is neither contaminated by poor sanitation nor by unpalatable mineral salts. Tests undertaken on water samples drawn from river sands have indicated that contamination occurs only after abstraction from containers. Water utilised from such sources is thus particularly suitable for both primary and secondary purposes. Where such systems can be established on low river banks, not too distant from the river edge, simple sand abstraction units provide an excellent, low cost method of abstracting water. Such systems are particularly appreciated by women who prefer small, low technology installations which they can operate themselves and can maintain simply and effectively.

  5. Variability of suspended sand concentrations, transport and eddy diffusivity under non-breaking waves on the shoreface

    NASA Astrophysics Data System (ADS)

    Vincent, Christopher E.; Downing, Andrew

    1994-02-01

    Suspended sand concentration profiles and current speed measurements were made in 1.6 ± 0.4m water depth on the seaward side of a bar beyond the break point at Stanhope Lane beach, Prince Edward Island, Canada, during a 4 day period. Two mild storm events occurred and 7 min-long bursts of 4.4 Hz data were recorded approximately every hour. Concentration profiles, with a resolution of 5 mm and 7.5 mm, were obtained using a 3 MHz acoustic backscatter (ABS) instrument. Some data on bed form dimensions were obtained by divers between storm events. Multiple bed echoes from the ABS also provide further information on the ripple heights but no direct observations were available at times of higher waves. During the 4 day period the local position of the bed decreased by about 8 cm, erosion occurring in two short (⋟6 h) periods, one during each storm event. Mean currents at this location were weak (<0.1 m s -1). The resuspension coefficient γ 0, calculated from the concentration at 2 cm above the bed, decreased as the wave height increased (in the break-off range) supporting the observations of VINCENTet al. [(1991) Marine Geology, 96, 1-18]. Large inter-burst variability was observed in the concentration profiles and in the eddy diffusivity and suspended transport fluxes computed from these profiles. This variability was due to the short length of record (⋟7min) relative to wave groups and to the location of the ABS relative to bed forms; to obtain consistent concentration and transport fluxes it is necessary to average many bursts over a time scale that is long compared to both groupiness and bed form mobility. Except at the beginning and end of events when wave conditions were changing rapidly, averaging over groups of bursts with similar wave conditions produced eddy diffusivity profiles characterized by a linear ɛ s gradient of (20 ±2.5) cm s -1 from the sea bed to 20 ± 5cm, beyond which ɛ s slowly decreased, and a suspended sand transport which was all below

  6. Cross-bedded limestone facies on San Salvador Island, Bahamas: New perspective on eolian calcarenites

    SciTech Connect

    Caputo, M.V. )

    1989-08-01

    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.

  7. Broadband Scattering from Sand and Sand/Mud Sediments with Extensive Environmental Characterization

    DTIC Science & Technology

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Broadband Scattering from Sand and Sand /Mud Sediments...TERM GOALS To model the effects of volume heterogeneities, both discrete and continuous, in scattering from sand and mud sediments. A better...sediment. For the experiments in this effort, scattering data was collected in the Gulf of Mexico for a sand sediment and in St. Andrew’s Bay for a

  8. Fluidized bed boiler feed system

    DOEpatents

    Jones, Brian C.

    1981-01-01

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

  9. Visual accumulation tube for size analysis of sands

    USGS Publications Warehouse

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

    1956-01-01

    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.

  10. Debris-bed friction of hard-bedded glaciers

    USGS Publications Warehouse

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

    2005-01-01

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

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

    USGS Publications Warehouse

    LeBlanc, D.R.

    1982-01-01

    Secondarily treated domestic sewage has been disposed of to a sand and gravel aquifer by infiltration through sand beds at Otis Air Force Base, Massachusetts, since 1936. The disposal has formed a plume of contaminated ground water that is more than 11 ,000 feet long, is 2,500 to 3,500 feet wide and 75 feet thick, and is overlain by 20 to 50 feet of uncontaminated ground water derived from precipitation. The distributions of specific conductance, temperature, boron chloride, sodium, phosphorus, nitrogen, ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. The center of the plume contains up to 2.6 milligrams per liter detergents as MBAS (methylene blue active substances), 0.4 milligram per liter boron, 20 milligrams per liter ammonia-nitrogen, and specific conductance as high as 405 micromhos per centimeter. Corresponding levels in uncontaminated ground water are less than 0.1 milligram per liter detergents, less than 0.1 ammonia-nitrogen, less than 0.05 milligram per liter boron, and less than 80 micromhos per centimeter specific conductance. Chloride, sodium, and boron concentrations seem to be affected only by hydrodynamic dispersion. Phosphorus movement is greatly retarded by sorption. Detergent concentrations exceed 0.5 milligram per liter from 3 ,000 to 10,000 feet from the sand beds and reflect the use of nonbiodegradable detergents from 1946 through 1964. The center of the plume as far as 5,000 feet from the sand beds contains nitrogen as ammonia, no nitrate, and no dissolved oxygen. Ammonia is oxidized to nitrate gradually with distance from the center of the plume. (USGS)

  12. Fluidized bed deposition of diamond

    DOEpatents

    Laia, Jr., Joseph R.; Carroll, David W.; Trkula, Mitchell; Anderson, Wallace E.; Valone, Steven M.

    1998-01-01

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

  13. Method for packing chromatographic beds

    DOEpatents

    Freeman, David H.; Angeles, Rosalie M.; Keller, Suzanne

    1991-01-01

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

  14. 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...

  15. Central Asian sand seas climate change as inferred from OSL dating

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  16. Investigating Sand on the Coast of Oregon and Washington.

    ERIC Educational Resources Information Center

    Komar, Paul D.

    2002-01-01

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

  17. Sand dune tracking from satellite laser altimetry

    NASA Astrophysics Data System (ADS)

    Dabboor, Mohammed

    Substantial problems arise from sand movement in arid and semi-arid countries. Sand poses a threat to infrastructure, agricultural and urban areas. These issues are caused by the encroachment of sand on roads and railway tracks, farmland, towns and villages, and airports, to name a few. Sand movement highly depends on geomorphology including vegetation cover, shape and height of the terrain, and grain size of the sand. However, wind direction and speed are the most important factors that affect efficient sand movement. The direction of the movement depends on the main direction of the wind, but it has been shown that a minimum wind speed is required, e.g. wind gusts, to initiate sand transport. This fact prevents a simple calculation of sand transport from conventional wind data as wind records rarely contain sub-minute intervals masking out any wind gusts. An alternative of predicting sand transport is the direct observation of sand advance by in situ measurements or via satellite. Until recently, satellite imagery was the only means to compare dune shape and position for predicting dune migration over several years. In 2003, the NASA laser altimetry mission ICESat became operational and monitors elevations over all surface types including sand dunes with an accuracy of about 10-20 cm. In this study, ICESat observations from repeat tracks (tracks overlapping eachother within 50 m) are used to derive sand dune advance and direction. The method employs a correlation of the elevation profiles over several dunes and was sucessfully validated with synthetic data. The accuracy of this method is 5 meters of dune advance. One of the most active areas exhibiting sand and dune movement is the area of the Arabian Peninsula. Approximately one-third of the Arabian Peninsula is covered by sand dunes. Different wind regimes (Shamal, Kaus) cause sand dune movement in the selected study area in the eastern part of the Arabian Peninsula between 20-25 degrees North and 45-55 degrees

  18. Variability of bed drag on cohesive beds under wave action

    USGS Publications Warehouse

    Safak, Ilgar

    2016-01-01

    Drag force at the bed acting on water flow is a major control on water circulation and sediment transport. Bed drag has been thoroughly studied in sandy waters, but less so in muddy coastal waters. The variation of bed drag on a muddy shelf is investigated here using field observations of currents, waves, and sediment concentration collected during moderate wind and wave events. To estimate bottom shear stress and the bed drag coefficient, an indirect empirical method of logarithmic fitting to current velocity profiles (log-law), a bottom boundary layer model for combined wave-current flow, and a direct method that uses turbulent fluctuations of velocity are used. The overestimation by the log-law is significantly reduced by taking turbulence suppression due to sediment-induced stratification into account. The best agreement between the model and the direct estimates is obtained by using a hydraulic roughness of 10  m in the model. Direct estimate of bed drag on the muddy bed is found to have a decreasing trend with increasing current speed, and is estimated to be around 0.0025 in conditions where wave-induced flow is relatively weak. Bed drag shows an increase (up to fourfold) with increasing wave energy. These findings can be used to test the bed drag parameterizations in hydrodynamic and sediment transport models and the skills of these models in predicting flows in muddy environments.

  19. Dynamic bed reactor

    SciTech Connect

    Stormo, K.E.

    1996-07-02

    A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix. 27 figs.

  20. Dynamic bed reactor

    SciTech Connect

    Stormo, Keith E.

    1996-07-02

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

  1. Dinural patterns of blowing sand and dust

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The diurnal pattern of blowing sand results from a complex interaction between the sun, the atmosphere, and the sand surface. During the day, solar heating produces thermal instability, which enhances convective mixing of high momentum winds from the upper levels of the atmosphere to the surface la...

  2. Introduction to Exploring Sand and Water

    ERIC Educational Resources Information Center

    Early Childhood Today, 2006

    2006-01-01

    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…

  3. Explorations with the Sand and Water Table.

    ERIC Educational Resources Information Center

    Texas Child Care, 2001

    2001-01-01

    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)

  4. Sand transportation and reverse patterns over leeward face of sand dune

    NASA Astrophysics Data System (ADS)

    Jiang, Hong; Dun, Hongchao; Tong, Ding; Huang, Ning

    2017-04-01

    Sand saltation has complex interactions with turbulent flow and dune form. Most models of wind-blown sand consider ideal circumstances such as steady wind velocity and a flat surface, and the bulk of data on wind flow and sand transport over an individual dune has focused mostly on the influence of dune shape or inter-dune space on the wind flow, neglecting the effect of morphology on sand saltation, particularly airflow and sand transportation over the leeward slope. Wind flow structures over the leeward slope of sand dunes have a fundamental influence on the organization of sand dunes. In order to understand sand dune dynamics, lee face airflow and sediment transportation should be paid more attention. Previous field observations could not measure turbulent flow structure well because of the limited observation points and the influence of experiment structure on wind field. In addition, the reverse sand particles over leeward face could not be collected by sand trap in field. Numerous field observations could not measure turbulent flow structure because of the limited observation points and the influence of experimental structures on the wind field. In addition, the reverse transport of sand particles over leeward face could not be collected by sand traps in field. Therefore, this paper aims to investigate the turbulent flow structure and sand transport pattern over the leeward slope. A numerical model of sand saltation over slope terrain is constructed, which also considers the coupling effects between air flow and sand particles. The large eddy simulation method is used to model turbulent flow. Sand transport is simulated by tracking the trajectory of each sand particle. The results show that terrain significantly alters the turbulent air flow structure and wind-blown sand movement, especially over the leeward slope. Here, mass flux increases initially and then decreases with height in the reversed flow region in the direction of wind flow, and the mass flux

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

    USGS Publications Warehouse

    Dingler, John R.; Reiss, Thomas E.

    1987-01-01

    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.

  6. Hematite Outlier and Sand Dunes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 4 December 2003

    This image shows a crater just south of the edge of the famous hematite-bearing surface, which is visible in the context image as a smooth area to the north. The crater has two features of immediate note. The first is a layered mound in the north part of the crater floor. This mound contains hematite, and it is an outlying remnant of the greater deposits to the north that have otherwise completely disappeared in this crater. The second feature is a dune field in the center of the crater floor, with dark dunes indicating winds from the northwest. The dunes grade into a dark sand sheet with no coherent structure, indicating that the sand layer thins out to the south and east.

    Image information: VIS instrument. Latitude -4.4, Longitude 357.3 East (2.7 West). 19 meter/pixel resolution.

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

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

  7. Ecological release in White Sands lizards

    PubMed Central

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

    2011-01-01

    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. PMID:22393523

  8. Earth-like sand fluxes on Mars.

    PubMed

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

    2012-05-09

    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.

  9. Fluidized bed combustion of low-grade coal and wastes: Research and development

    SciTech Connect

    Borodulya, V.A.; Dikalenko, V.I.; Palchonok, G.I.; Vinogradov, L.M.; Dobkin, S.M.; Telegin, E.M.

    1994-12-31

    Experimental studies were carried out to investigate devolatilization of fuel as single spherical particles of wood, hydrolytic lignin, leather sewage sludge and Belarussian brown coals in a fluidized bed of sand. It is found that the devolatilization process depends on moisture and ash contents in fuel and on the external heat and mass transfer rate. The char combustion occurs largely in the intermediate region. Kinetic parameters of the devolatilization and char combustion are obtained. A low-capacity fluidized bed boiler suitable for combustion of coal and different wastes is described.

  10. Bed Bug Laws and Regulations

    EPA Pesticide Factsheets

    21 states have some level of regulation with regard to bed bugs. Most of these requirements focus on hotels and landlords or other property managers. The Department of Housing and Urban Development has guidance on controlling bed bugs in public housing.

  11. LSP Composite Test Bed Design

    NASA Technical Reports Server (NTRS)

    Day, Arthur C.; Griess, Kenneth H.

    2013-01-01

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

  12. SMART NAS Test Bed Overview

    NASA Technical Reports Server (NTRS)

    Palopo, Kee

    2016-01-01

    These slides presents an overview of SMART NAS Test Bed. The test bed is envisioned to be connected to operational systems and to allow a new concept and technology to be evaluated in its realistic environment. Its role as an accelerator of concepts and technologies development, its use-case-driven development approach, and its state are presented.

  13. Effectiveness of Bed Bug Pesticides

    EPA Pesticide Factsheets

    Before EPA allows a bed bug claim on a label, the product must be supported by data showing it will kill bed bugs when applied according to the label. Also take into accounts factors such as extent of infestation, site preparation, and insect life stages.

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

    USGS Publications Warehouse

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

    1998-01-01

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

  15. Ability of bed bug-detecting canines to locate live bed bugs and viable bed bug eggs.

    PubMed

    Pfiester, Margie; Koehler, Philip G; Pereira, Roberto M

    2008-08-01

    The bed bug, Cimex lectularius L., like other bed bug species, is difficult to visually locate because it is cryptic. Detector dogs are useful for locating bed bugs because they use olfaction rather than vision. Dogs were trained to detect the bed bug (as few as one adult male or female) and viable bed bug eggs (five, collected 5-6 d after feeding) by using a modified food and verbal reward system. Their efficacy was tested with bed bugs and viable bed bug eggs placed in vented polyvinyl chloride containers. Dogs were able to discriminate bed bugs from Camponotus floridanus Buckley, Blattella germanica (L.), and Reticulitermes flavipes (Kollar), with a 97.5% positive indication rate (correct indication of bed bugs when present) and 0% false positives (incorrect indication of bed bugs when not present). Dogs also were able to discriminate live bed bugs and viable bed bug eggs from dead bed bugs, cast skins, and feces, with a 95% positive indication rate and a 3% false positive rate on bed bug feces. In a controlled experiment in hotel rooms, dogs were 98% accurate in locating live bed bugs. A pseudoscent prepared from pentane extraction of bed bugs was recognized by trained dogs as bed bug scent (100% indication). The pseudoscent could be used to facilitate detector dog training and quality assurance programs. If trained properly, dogs can be used effectively to locate live bed bugs and viable bed bug eggs.

  16. 13. SANDSORTING BUILDING, THIRD FLOOR, VIBRATING SCREENS FOR SAND SORTING, ...

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

    13. SAND-SORTING BUILDING, THIRD FLOOR, VIBRATING SCREENS FOR SAND SORTING, LOOKING SOUTHWEST - Mill "C" Complex, Sand-Sorting Building, South of Dee Bennet Road, near Illinois River, Ottawa, La Salle County, IL

  17. Blood volume responses of men and women to bed rest

    NASA Technical Reports Server (NTRS)

    Fortney, S. M.; Turner, C.; Steinmann, L.; Driscoll, T.; Alfrey, C.

    1994-01-01

    This paper reviews a series of studies that indicate that estrogens play an important role in blood volume regulation. The first study illustrates that the plasma volume (PV) of ambulatory women fluctuates during the menstrual cycle, increasing during periods of elevated estrogens. In the second study, it was shown that exogenous and endogenous elevations in blood estrogens attenuate the decrease in PV during bed rest. In the third study, the hypothesis was tested that women, who naturally have a higher blood estrogen content compared with men, will have a smaller loss of PV during bed rest. Ten men and ten women underwent a 13-day, 6 degrees head-down bed rest. Plasma volume and red cell mass (RCM) were measured before and after bed rest using 125I and 51Cr labeling, respectively. Before bed rest, the men and women had similar blood volume (BV) and PV (mL/kg body weight), but the women had a smaller (P < .01) RCM (22.2 +/- 0.9 versus 26.2 +/- 0.8 mL/kg, mean +/- SE). During bed rest, the decrease in RCM (mL/kg) was similar in men and women. However, the decrease in BV was greater in men (8.0 +/- 0.8 mL/kg versus 5.8 +/- 0.8 mL/kg), because of a greater reduction in PV (6.3 +/- 0.6 mL/kg versus 4.1 +/- 0.6 mL/kg). Because the decline in BV has been proposed to contribute to the cardiovascular deconditioning after bed rest, it is possible that women may experience less cardiac and circulatory strain on reambulation.

  18. Assessing environmental risk of the retired filter bed area, Battelle West Jefferson

    SciTech Connect

    Miller, S.F.; Thompson, M.D.; Glennon, M.A.

    1997-04-01

    Initial investigations conducted by the U.S. Department of Energy, Chicago Operations Office, and by Argonne National Laboratory used seismic refraction profiling, electrical resistivity depth sounding, conductivity profiling, magnetic gradiometry, and ground-penetrating radar to study environmental geophysics in the area of the Battelle West Jefferson site`s radiologically contaminated retired filter beds. The investigators used a combination of nonintrusive technologies and innovative drilling techniques to assess environmental risk at the filter beds and to improve understanding of the geology of the Big Darby Creek floodplain. The geophysical investigation, which showed that the preferred groundwater pathway is associated with a laterally extensive deposit of silty sand to sand that is less than 12 ft deep in the floodplain area, also guided the location of cone penetrometer test sites and piezometer installation. Cone penetrometer testing was useful for comparing continuous logging data with surface geophysical data in establishing correlations among unconsolidated materials.

  19. Sand waves at the mouth of San Francisco Bay, California

    USGS Publications Warehouse

    Gibbons, Helen; Barnard, Patrick L.

    2007-01-01

    The U.S. Geological Survey; California State University, Monterey Bay; U.S. Army Corps of Engineers; National Oceanic and Atmospheric Administration; and Center for Integrative Coastal Observation, Research and Education partnered to map central San Francisco Bay and its entrance under the Golden Gate Bridge using multibeam echosounders. View eastward, through the G