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1

Two-phase Lattice Boltzmann Simulation Study on Flow Pattern in a Silty Sand Model  

NASA Astrophysics Data System (ADS)

The spilled oil can be trapped in porous media, such as beach sand, wetland soils and marine sediments, over decades after the disaster of oil spill, which is dependent on the type of the sediments. Silty sand is a prototype of the sediments, where the pore space between sand grains (~100 microns) can be filled by silt grains (a few microns to tens of microns). Here, we have studied the drainage of oil into a silty sand model initially saturated with water by using lattice Boltzmann simulations. The simulation study has been compared with micro-capillary video microscopy experiments. The aim of this study is to understand the oil spill pattern and the flow dynamics inside the sedimentary media, which is so opaque that the flow pattern (inside it) is invisible. Lattice Boltzmann, which is one of the computational fluid dynamics methods, is adopted as a tool of computing two-phase immiscible fluid flow in this study. This method has several strong points: above all, complicated fluid-solid boundary can be easily applied. In this study, the capillary number is varied not only by changing fluid velocity, but by changing interfacial tension. As a porous media, granular model, which is made by packing of a lot of same-sized spherical elements (silt grains), is adopted. The discontinuous oil front migration is observed in the case of low capillary number, whereas, the relationship between oil-traveled distance and simulation time was close to linear in the case of high capillary number. The breakthrough time and capillary number has a linear relation in log-log scale, when changing only fluid velocity. Additionally, the relationship is also linear when changing interfacial tension. However, the slopes of the two lines are different and the line slope in changing fluid velocity is steeper. While the simulation is generally consistent with experimental result, it further enables us understand the flow dynamics in detail. Further study is undergoing towards the underlining mechanism of the observed linear relationship.

Yamabe, H.; Tsuji, T.; Liang, Y.; Matsuoka, T.

2012-12-01

2

Food-chain relationships in subtidal silty sand marine sediments and the role of meiofauna in stimulating bacterial productivity  

Microsoft Academic Search

From bibliographic data the biomass correlations (organic dry weight) are constructed for the subsurface layer of a hypothetical 30 m deep silty sand station: 200 µg\\/ml macrofauna (including 120 µg\\/ml subsurface deposit feeders), 50 µg\\/ml meiofauna, 20 µg\\/ml Foraminifera, 1 µg\\/ml Ciliata and Flagellata, and 100 µg\\/ml bacteria. ATP-biomass is discussed.

Sebastian A. Gerlach

1978-01-01

3

Numerical evaluation of seismic response of shallow foundation on loose silt and silty sand  

NASA Astrophysics Data System (ADS)

This study includes the results of a set of numerical simulations carried out for sands containing plastic/non-plastic fines, and silts with relative densities of approximately 30-40% under different surcharges on the shallow foundation using FLAC 2D. Each model was subjected to three ground motion events, obtained by scaling the amplitude of the El Centro (1940), Kobe (1995) and Kocaeli (1999) Q12earthquakes. Dynamic behaviour of loose deposits underlying shallow foundations is evaluated through fully coupled nonlinear effective stress dynamic analyses. Effects of nonlinear soil structure interaction (SSI) were also considered by using interface elements. This parametric study evaluates the effects of soil type, structure weight, liquefiable soil layer thickness, event parameters (e.g., moment magnitude of earthquake ( M w ), peak ground acceleration PGA, PGV/PGA ratio and the duration of strong motion ( D 5-95) and their interactions on the seismic responses. Investigation on the effects of these parameters and their complex interactions can be a valuable tool to gain new insights for improved seismic design and construction.

Asgari, Ali; Golshani, Aliakbar; Bagheri, Mohsen

2014-03-01

4

Behavior of Nonplastic Silty Soils under Cyclic Loading  

PubMed Central

The engineering behavior of nonplastic silts is more difficult to characterize than is the behavior of clay or sand. Especially, behavior of silty soils is important in view of the seismicity of several regions of alluvial deposits in the world, such as the United States, China, and Turkey. In several hazards substantial ground deformation, reduced bearing capacity, and liquefaction of silty soils have been attributed to excess pore pressure generation during dynamic loading. In this paper, an experimental study of the pore water pressure generation of silty soils was conducted by cyclic triaxial tests on samples of reconstituted soils by the slurry deposition method. In all tests silty samples which have different clay percentages were studied under different cyclic stress ratios. The results have showed that in soils having clay content equal to and less than 10%, the excess pore pressure ratio buildup was quicker with an increase in different cyclic stress ratios. When fine and clay content increases, excess pore water pressure decreases constant cyclic stress ratio in nonplastic silty soils. In addition, the applicability of the used criteria for the assessment of liquefaction susceptibility of fine grained soils is examined using laboratory test results. PMID:24672343

Ural, Nazile; Gunduz, Zeki

2014-01-01

5

Filler effect of fine particle sand on the compressive strength of mortar  

Microsoft Academic Search

The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was\\u000a replaced by the ground river sands at 10wt%–40wt% of binder to cast mortar. Compressive strengths of mortar were investigated\\u000a and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results\\u000a show

Chai Jaturapitakkul; Jatuphon Tangpagasit; Sawang Songmue; Kraiwood Kiattikomol

2011-01-01

6

Filler effect of fine particle sand on the compressive strength of mortar  

NASA Astrophysics Data System (ADS)

The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was replaced by the ground river sands at 10wt%-40wt% of binder to cast mortar. Compressive strengths of mortar were investigated and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results show that the compressive strength of mortar contributed from the filler effect of smaller particles is higher than that of the coarser ones. The difference in compressive strength of mortar tends to be greater as the difference in ground river sand fineness increases. The results also suggest that ASTM C618 specification is not practically suitable for specifying pozzolan in concrete since the strength activity index of mortar containing ground river sand (high crystalline phase) with 33.8wt% of particles retained on a 45-?m sieve can pass the strength requirement.

Jaturapitakkul, Chai; Tangpagasit, Jatuphon; Songmue, Sawang; Kiattikomol, Kraiwood

2011-04-01

7

Coal-sand attrition system and its importance in fine coal cleaning. Final report  

SciTech Connect

It is known that ultra-fine coals are prerequisite for the deep cleaning of most US coal seams if environmental pollution arising from the use of such coals is to be minimized. Therefore, the production of finely liberated coal particles in conjunction with reduced heavy metal contaminants at low costs is desirable, if not mandatory. The liberation of intimately disseminated impurities from the coal matrix therefore, demands that the material be ground to a high degree of fineness. Similarily, some technologies for coal utilization require superfine particles (i.e., sizes less than ten microns). This implies additional costs for coal preparation plants due to the high energy and media costs associated with fine grinding operations. Besides, there are problems such as severe product contaminations due to media wear and impairment of the quality of coal. Hence, proper choice of grinding media type is important from the viewpoints of cost reduction and product quality. The use of natural quartz sand as grinding media in the comminution of industrial minerals in stirred ball mills has been indicated. The advantages of natural sand compared to steel media include low specific energy inputs, elimination of heavy metal contaminants and low media costs. In this work, the effect of rotor speed, solids concentration and feed-size are studied on four coals in conjunction with silica sand and steel shot. The results obtained are used to evaluate the suitability of silica sands as an alternative grinding media. for coal. Coal-sand and coal-steel systems are compared in terms of specific energy consumption, product fineness, media/wear contaminationanalysis and calorific values, liberation spectrum and particle shape characteristics. In general cleaner flotation concentrate was obtained from coals when they were ground with sand media. The zeta potential of coals was found to be different and lower when they ground with sand.

Mehta, R.K.; Zhu, Qinsheng

1993-08-01

8

Total sand inputFine nose Non-equilibrium tail Equilibrium tail  

E-print Network

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

Watson, Andrew

9

Piling in fine and medium sand—a case study of ground and pile vibration  

Microsoft Academic Search

The paper presents the results of the measurement of ground and pile vibrations from a field investigation of prototype piling in which a steel casing of 600 mm diameter was driven in fine and medium sand for a depth of 16.4 m by impacting a hammer of mass 4100 kg dropped from a height of 2.4 m by a motorised

T. S. Thandavamoorthy

2004-01-01

10

Absence of shape sorting of fine sand by the braided William-River, northern Saskatchewan  

SciTech Connect

Sorting of sedimentary particles on the basis of shape is one of many mechanisms by which the characteristics of sediment samples may change along a transport path. The question of the importance of shape sorting of fine sand in fluvial systems is unresolved, due mainly to the difficulty of adequately measuring shape of small particles with irregular morphology, and eliminating other shape influencing processes primarily multiple sources. The study area and analytical techniques were chosen to eliminate these two problems. The William River, a braided river in northern Saskatchewan, is constructing a delta into Lake Athabasca. The 5 km supradeltaic portion of the stream receives no sediment other than from the single fluvial source. 400-500 quartz particles within the fine sand fraction (180-250 microns) of 15 stream samples were analyzed via Fourier techniques. Results indicate that braided river transport processes do not selectively transport fine sand particles on the basis of shape, either at gross scale (elongation) or smaller scale surface roughness. Littoral drift processes, in contrast, have been shown to select on the basis of both elongation and surface roughness. The differences in shape selectivity may be due to transport by traction versus suspension. Analysis should, however, be extended to other grain sizes.

Kennedy, S.K.

1985-01-01

11

Bauxite residue fines as an amendment to residue sands to enhance plant growth potential—a glasshouse study  

Microsoft Academic Search

Purpose  This glasshouse study was conducted to determine if amending bauxite residue sand with residue fines would improve its suitability\\u000a as a growth medium. Alcoa’s West Australian operations mechanically separate residue into two size fractions: residue fines\\u000a (which are dominated by particles 150 ?m). Residue sand represents the primary material used\\u000a as a growth medium for rehabilitation, and prior to amendments, it

Jonathan D. Anderson; Richard W. Bell; Ian R. Phillips

12

Ultrahigh-resolution mass spectrometry of simulated runoff from treated oil sands mature fine tailings.  

PubMed

There is interest in using mature fine tailings (MFT) in reclamation strategies of oil sands mining operations. However, simulated runoff from different dried MFT treatments is known to have elevated levels of salts, toxic ions, and naphthenic acids, and alkaline pH and it is phytotoxic to the emergent macrophyte, common reed (Phragmites australis). Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of the acidic species in the runoff confirmed that the distribution of oil sands naphthenic acids and associated oil sand acids was dependent on the MFT treatment. Furthermore, FT-ICR MS studies of the acidic species in hydroponic systems revealed that there was no plant-mediated change in the electrospray ionization mass spectra of the runoff. O(o)-containing species were prevalent (>90%), O(o)S(s) were predominant (<10% relative abundance), and O(o)N(n) were least abundant in all runoff water samples. O(o)S(s) species were predominant in all the samples investigated. The heteroatomic classes present in runoff water at greater than 1% relative abundance include: O(2)N(1), O(3)N(1), O(2), O(2)S(1) O(3), O(3)S(1), O(4), O(4)S(1), O(5), O(5)S(1), O(6), O(6)S(1), O(7), O(7)S(1), O(8) and O(8)S(1). Assuming the same response factor for all O(o) species, the O(4) class, presumably dicarboxylic acids, was generally more prevalent than the O(2) class in all samples. The O(2) class is indicative of classical naphthenic acids. However, dicarboxylic acids will form negative ions more readily than the monocarboxylic acids as there are two acidic hydrogens available for formation of these species. PMID:20635394

Headley, John V; Armstrong, Sarah A; Peru, Kerry M; Mikula, Randy J; Germida, James J; Mapolelo, Mmilili M; Rodgers, Ryan P; Marshall, Alan G

2010-08-30

13

Dry mature fine tailings as oil sands reclamation substrates for three native grasses.  

PubMed

Mature fine tailings (MFT) are a by-product of oil sands mining that must be reclaimed through capping or use as a reclamation substrate. Some chemical and physical properties of MFT make it inhospitable for plant growth, such as high concentrations of sodium, sulfate, chloride, and hydrocarbons. A greenhouse study assessed whether substrates of various mixes of dry MFT, overburden sand, and peat mineral soil mix (PMM) and caps of forest floor organic material (LFH) and PMM would support the emergence and growth of three native grass species commonly used in land reclamation. Select vegetation properties were monitored for 16 wk in the greenhouse; select chemical and physical substrate properties were determined in the laboratory. was more tolerant of dry MFT than and . Mean aboveground and belowground biomass were more than twice as high on substrates with <60% MFT than on 100% MFT. Aboveground biomass was two to four times greater with capping than without and 30% greater on LFH than PMM caps. Cover and density followed similar trends. Belowground biomass on capped substrates was at least double that on uncapped substrates. Aboveground biomass was almost doubled with the use of fertilizer. High concentrations of hydrocarbons and exchangeable ions were associated with reduced plant growth and health. Results from this study show that capping, amendments, and fertilizer may improve the reclamation potential of dry MFT. PMID:25603099

Luna Wolter, Gabriela L; Naeth, M Anne

2014-07-01

14

The fine sand Abra alba community of the bay of morlaix twenty years after the Amoco Cadiz oil spill  

Microsoft Academic Search

The fine sand Abra alba community from the Bay of Morlaix (western English Channel) was strongly affected by the Amoco Cadiz oil spill of April 1978. The long term changes in the community (1977–1996) show that reconstitution of this community is slow (over 10 yr). A progressive recolonization by amphipod Ampelisca populations constituting the dominant species is observed. The results

J-C Dauvin

1998-01-01

15

Measuring solid percentage of oil sands mature fine tailings using the dual probe heat pulse method.  

PubMed

The reclamation of mature fine tailings (MFT) is a critical challenge for the oil sands industry in western Canada, and a nonradioactive, automated, and inexpensive method to monitor the MFT solidification is needed. The objective of this paper is to evaluate the feasibility of a dual-probe heat pulse (DPHP) method to measure MFT solid percentage. Dual-probe heat pulse measurements were performed on three MFT samples, each at various solid percentages. A linear relationship ( = 0.9495 + 0.0558) was established between the DPHP-measured solid percentage () and that of oven-dry method (). Six additional MFT samples were collected and measured to validate the DPHP method. The specific heats of the six MFT solids were measured independently using a modulated differential scanning calorimetry method, and the sensitivity of DPHP-measured MFT solid percentage to the specific heat of MFT solids was evaluated. The result shows that the DPHP method can be used to accurately measure MFT solid percentages, and the accuracy can be further improved if the specific heat of the MFT solids is measured independently. PMID:25602345

Li, Min; Barbour, S Lee; Si, Bing Cheng

2015-01-01

16

Modeling fine-scale geological heterogeneity--examples of sand lenses in tills.  

PubMed

Sand lenses at various spatial scales are recognized to add heterogeneity to glacial sediments. They have high hydraulic conductivities relative to the surrounding till matrix and may affect the advective transport of water and contaminants in clayey till settings. Sand lenses were investigated on till outcrops producing binary images of geological cross-sections capturing the size, shape and distribution of individual features. Sand lenses occur as elongated, anisotropic geobodies that vary in size and extent. Besides, sand lenses show strong non-stationary patterns on section images that hamper subsequent simulation. Transition probability (TP) and multiple-point statistics (MPS) were employed to simulate sand lens heterogeneity. We used one cross-section to parameterize the spatial correlation and a second, parallel section as a reference: it allowed testing the quality of the simulations as a function of the amount of conditioning data under realistic conditions. The performance of the simulations was evaluated on the faithful reproduction of the specific geological structure caused by sand lenses. Multiple-point statistics offer a better reproduction of sand lens geometry. However, two-dimensional training images acquired by outcrop mapping are of limited use to generate three-dimensional realizations with MPS. One can use a technique that consists in splitting the 3D domain into a set of slices in various directions that are sequentially simulated and reassembled into a 3D block. The identification of flow paths through a network of elongated sand lenses and the impact on the equivalent permeability in tills are essential to perform solute transport modeling in the low-permeability sediments. PMID:23252428

Kessler, Timo Christian; Comunian, Alessandro; Oriani, Fabio; Renard, Philippe; Nilsson, Bertel; Klint, Knud Erik; Bjerg, Poul Løgstrup

2013-01-01

17

Effects of alternative tillage systems on soil quality and yield of spring cereals on silty clay loam and sandy loam soils in the cool, wet climate of central Norway  

Microsoft Academic Search

Tillage trials were established on a poorly drained silty loam overlying silty clay loam and on a freely drained sandy loam overlying medium sand, in 1988 and 1989, respectively. Autumn and spring ploughing and two ploughless systems were compared for 12–13 years, with three replications at each site. The ploughless treatments comprised deep versus shallow spring harrowing until 1999, and

H. C. F. Riley; M. A. Bleken; S. Abrahamsen; A. K. Bergjord; A. K. Bakken

2005-01-01

18

Phytotoxicity and naphthenic acid dissipation from oil sands fine tailings treatments planted with the emergent macrophyte Phragmites australis.  

PubMed

During reclamation the water associated with the runoff or groundwater flushing from dry stackable tailings technologies may become available to the reclaimed environment within an oil sands lease. Here we evaluate the performance of the emergent macrophyte, common reed (Phragmites australis), grown in chemically amended mature fine tailings (MFT) and simulated runoff/seepage water from different MFT drying treatments. The present study also investigated the phytotoxicity of the concentration of oil sands naphthenic acids (NAs) in different MFT drying chemical treatments, in both planted and unplanted systems. We demonstrate that although growth was reduced, the emergent macrophyte common reed was capable of growing in diluted unamended MFT runoff, as well as in diluted runoff from MFT amended with either 0.25% lime and gypsum or 0.5% gypsum. Common reed can thus assist in the dewatering process of oil sands MFT. However, simulated runoff or seepage waters from chemically amended and dried MFT were phytotoxic, due to combined levels of salts, naphthenic acids and pH. Phytoremediation of runoff water/ground water seepage from dry-land applied MFT will thus require pre-treatment in order to make conditions more favorable for plant growth. PMID:20486009

Armstrong, Sarah A; Headley, John V; Peru, Kerry M; Mikula, Randy J; Germida, James J

2010-01-01

19

Sources and distribution of fine quartz sand in the northeastern Gulf of Mexico: a paleogeographic reconstruction using fourier grain shape analysis  

E-print Network

SOURCES AND DISTRIBUTION OF FINE QUARTZ SAND IN THE NORTHEASTERN GULF OF MEXICO: A PALE OGEOGRAPHIC RECON'STRUCT I ON USING F OURI ER GRAIN SHAPE ANALYSIS A Thesis by CHARLES ARTHUR BATES Submitted to the Graduate College of Texas ASM... ABSTRACT Sources and Distribution of Fine quartz Sand in the Nourtheastern Gulf of Mexico: A Paleogeographic Reconstruction us1ng Fourier Gra1n Shape Analysis IMay, 1985) Charles Arthur Bates, B. S, The University of Texas at Austin Chairman of Adv1...

Bates, Charles Arthur

2012-06-07

20

Step-scan photoacoustic fourier transform and X-rays photoelectron spectroscopy of oil sands fine tailings: new structural insights.  

PubMed

The chemical and physical properties of clay suspensions from oil sands have profound effect not only on the bitumen extraction process but also on the tailing treatment and reclamation. Step-scan Photoacoustic Fourier Transform Infrared (S2PAS-FTIR) has been used to characterize the properties of clay suspensions. The photoacoustic spectral features of the fine solids (FS) fraction were found to vary drastically with the modulation frequency. This is attributed to the increase in the relative amount of bitumen-like matter in the bulk. A similar behavior was observed on the bi-wetted solid (BWS) fraction, in spite of the fact that the variation as a function of the modulation frequency is less significant. No such change is observed on hydrophobic solid (HPS) sample. These observations allow us to refine our pictorial image of the bitumen fraction materials structure. PMID:11765796

Bensebaa, F; Majid, A; Deslandes, Y

2001-11-01

21

Step-scan Photoacoustic Fourier Transform and X-rays photoelectron spectroscopy of oil sands fine tailings: new structural insights  

NASA Astrophysics Data System (ADS)

The chemical and physical properties of clay suspensions from oil sands have profound effect not only on the bitumen extraction process but also on the tailing treatment and reclamation. Step-scan Photoacoustic Fourier Transform Infrared (S 2PAS-FTIR) has been used to characterize the properties of clay suspensions. The photoacoustic spectral features of the fine solids (FS) fraction were found to vary drastically with the modulation frequency. This is attributed to the increase in the relative amount of bitumen-like matter in the bulk. A similar behavior was observed on the bi-wetted solid (BWS) fraction, in spite of the fact that the variation as a function of the modulation frequency is less significant. No such change is observed on hydrophobic solid (HPS) sample. These observations allow us to refine our pictorial image of the bitumen fraction materials structure.

Bensebaa, Farid; Majid, Abdul; Deslandes, Yves

2001-11-01

22

Measuring Static and Dynamic Properties of Frozen Silty Soils  

SciTech Connect

A mechanical characterization of frozen silty soils has been conducted to support computer modeling of penetrators. The soils were obtained from the Eilson AFB (Alaska) vicinity. Quasi-static testing with a multiaxial system in a cold room and intermediate strain rate testing with a split Hopkinson pressure bar were conducted. Maximum stresses achieved were slightly above 1 GPa, apparently limiting the observed behavior primarily to elastic compression and pore crushing phenomena. Lower temperatures seem to increase the strength of the material markedly, although not by a simple factor. Lower temperatures and higher strain rates increase the apparent Young's and bulk moduli as well (an increase of {approximately} a factor of two is observed for strain rate increasing from 0.001 s{sup {minus}1} to 800 s{sup {minus}1}). The strength also depends strongly on strain rate. Increasing the strain rate from 0.001 {sup {minus}1} to 0.07 {sup {minus}1} increases the strength by a factor of five to ten (to values of order 1 GPa). However,only a small increase in strength is seen as strain rate is increased to {approximately} 10{sup 2}--10{sup 3} s{sup {minus}1}. The reliability of the strength measurements at strain rates< 1 s{sup {minus}1} is decreased due to details of the experimental geometry, although general trends are observable. A recipe is provided for a simulant soil based on bentonite, sand, clay-rich soil and water to fit the {approximately} 6% air-filled porosity, density and water content of the Alaska soils, based on benchtop mixing and jacketed compression testing of candidate mixes.

Furnish, M.D.

1998-09-30

23

Experimental and numerical understanding of a splashing drop onto fine sand samples  

NASA Astrophysics Data System (ADS)

Water erosion phenomenons are increasingly studied and understood but raindrop erosion is far more complex. Raindrop erosion includes subprocesses such as impact, cratering, rim formation, daughter drop splash and soil particle splash. This work is focused on modeling complex ballistic trajectories of soil particle splashes and particle dispersion process. The general purpose is first to recreate the splash effect in laboratory and second to provide optimal numerical models and a better understanding of the soil particle splash. Since the complex multiphase interactions are difficult to model, it is easier to compute numerically the dispersion process. Physical based models are the most common approach in this investigation field. The first assumption is that the crater shape might be the controlling factor in the dispersion process governed by the average splash distance. Moreover, complex physical based models may govern ballistic trajectories. These assumptions have now to be proven. Phenomenological observations are given by experiments in laboratory, on a setup inspired by Furbish et al. (2007) study. Fine soil samples are used in this work and advanced grain size analysis is performed using laser diffraction technique. High-speed camera acquisitions and micro-LiDAR records are used throughout experimental investigations. Then, impact velocities are measured as well as crater shape or particle dispersion. Measured velocities tend to be close to those computed by numerical simulations. High-speed photography analysis shows that the mean initial splash angle is dependent on the drop penetration depth. Moreover, the mean splash angle seems to be dependent on the slope at the crater edge. Numerical computation is then performed to model the dispersion phenomenon. Using a probabilistic algorithm, the grain size distribution can be taken into account throughout numerical simulation. The initial splash angle mean value is derived from previous assumption about the key role of the crater shape. Gravity, drag and buoyant forces are also taken into account. Model validation is performed by comparisons between experimental and numerical results using digitalized experimental dispersion photography and LiDAR scanning. Further perspectives should be oriented in multiphase interactions (fluid to soil particle) for a better understanding of the whole phenomenon.

Wyser, Emmanuel; Rudaz, Benjamin; Jaboyedoff, Michel

2014-05-01

24

Reservoir characteristics of two minter oil sands based on continuous core, E-logs, and geochemical data: Bee Brake field, East-Central Louisiana  

SciTech Connect

The Bee Brake field area, located in township 4N/6E and 4N/7E in Concordia Parish, has been one of the more prolific oil-producing areas in east-central Louisiana. Production decline in various fields, however, has sparked interest in the economic feasibility of locating and producing the remaining bypassed oil in the lower Wilcox. For this purpose, the Angelina BBF No. 1 well was drilled, and a 500-ft conventional core and a complete suite of state-of-the-are wireline logs were recovered. Production tests were run on the Minter interval of interest. The 16-ft Minter interval (6742-6758 ft depth), bounded at its top and base by lignite seams, consists of an upper 4-ft oil sand (Bee Brake) and a lower 3-ft oil sand (Angelina). The oil sands are separated by approximately 5 ft of thinly laminated silty shale and 4 ft of very fine-grained silty sandstone. Detailed sedimentologic and petrographic descriptions of the Minter interval provide accurate facies determinations of this lower delta-plain sequence. Petrophysical evaluation, combining core plug and modern electric-log data show differences between reservoir quality of the Bee Brake and Angelina sands. This data will also be useful for correlating and interpolating old electric logs. Organic geochemistry of the oil, lignites, and shales provides insight as to the source of the Minter oils and the sourcing potential of the lignites.

Echols, J.B.; Goddard, D.A.; Bouma, A. (Louisiana State Univ., Baton Rouge, LA (United States))

1993-09-01

25

A study of infiltration on three sand capillary barriers  

Microsoft Academic Search

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

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

2004-01-01

26

Kemik sandstone: inner shelf sand from northeast Alaska  

SciTech Connect

The upper Neocomian Kemik Sandstone crops out in and around Ignek Valley in northeast Alaska. It lies unconformably on the Jurassic to Lower Cretaceous Kingak Shale, and is overlain by the Hauterivian to Barremian Pebble shale. It is a fine-grained, glauconitic quartzose sandstone, up to 120 ft thick. Four lithofacies are recognized: (1) a basal, moderately well-sorted pebble conglomerate; (2) fine to very fine-grained, laminated and bioturbated sandstones; (3) a poorly sorted conglomerate; and (4) low-angle to hummocky cross-stratified fine-grained sandstones. Facies relationships suggest that the basal conglomerate represents a transgressive lag deposit. It is overlain by a sequence comprising laminated and bioturbated sandstones with interbedded, poorly sorted conglomerates. The sandstones exhibit a mixed assemblage of ichnofossils, including Gyrochorte, Muensteria, Ophiomorpha, Planolites, and Skolithos, and (.)Conichnus. In places, they grade upward from low-angle laminations to symmetrical ripple forms to silty laminated deposits. Their upper parts are bioturbated, but to varying extent. these sandstones and the conglomerates were deposited abruptly but sporadically below storm wave base by storm-generated currents. The sandstones were subsequently modified by strong but waning oscillating storm waves. The hummocky cross-stratified sediment comprises an upper sequence that was probably deposited under the influence of storm-induced conditions between fair-weather and storm wave base. The Kemik Sandstone represents a storm-deposited inner shelf sand with regressive characteristics, deposited within an overall transgressive setting.

Melvin, J.

1986-05-01

27

Hydraulic Fracturing Sand  

USGS Multimedia Gallery

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

28

Copper effects on bacterial activity of estuarine silty sediments  

NASA Astrophysics Data System (ADS)

Bacteria of silty estuarine sediments were spiked with copper to 200 ?g Cu g -1 dry weight sediment in order to assess the impact of copper on bacterial degradation of organic matter and on bacterial biomass production. Bacterial density was determined by direct counting under epifluorescence microscopy and bacterial production by the incorporation of 3H-Leucine. Leucine turnover rate was evaluated by 14C-leucine incorporation and ectoenzymatic activities were estimated as the hydrolysis rate of model substrates for ?-glucosidase and leucine-aminopeptidase. The presence of added copper in the microcosms elicited, after 21 days of incubation, generalised anoxia and a decrease in organic matter content. The non-eroded surface of the copper-spiked sediment showed, when compared to the control, a decrease in bacterial abundance and significant lower levels of bacterial production and of leucine turnover rate. Bacterial production and leucine turnover rate decreased to 1.4% and 13% of the control values, respectively. Ectoenzymatic activities were also negatively affected but by smaller factors. After erosion by the water current in laboratory flume conditions, the eroded surface of the control sediment showed a generalised decline in all bacterial activities. The erosion of the copper-spiked sediment showed, however, two types of responses with respect to bacterial activities at the exposed surface: positive responses of bacterial production and leucine turnover rate contrasting with slight negative responses of ectoenzymatic activities. The effects of experimental erosion in the suspended cells were also different in the control and in the copper-spiked sediment. Bacterial cells in the control microcosm exhibited, when compared to the non-eroded sediment cells, decreases in all activities after the 6-h suspension. The response of the average suspended copper-spiked sediment cell differed from the control by a less sharp decrease in ectoenzymatic activities and, mainly, by the great intensification of bacterial biomass production and leucine turnover rate. We conclude that the bacterial community of silty estuarine sediments seems to withstand considerable concentrations of copper at the cost of reduced bacterial organic matter degradation and of the almost halting of bacterial production. The toxic effects elicited by copper on protein and carbohydrate degradation were not rapidly repaired by erosion and oxygenation of the sediment cells but, in contrast, bacterial biomass production and leucine turnover were rapidly and efficiently reactivated.

Almeida, Adelaide; Cunha, Ângela; Fernandes, Sandra; Sobral, Paula; Alcântara, Fernanda

2007-07-01

29

A TOXICITY IDENTIFICATION EVALUATION OF SILTY MARINE HARBOR SEDIMENTS TO CHARACTERIZE PERSISTENT AND NON-PERSISTENT CONSTITUENTS  

EPA Science Inventory

Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide, leaving the adverse effects of persistent toxic substances unnoticed. To investigate the latter, we subjected interstitial water from three contaminated silty sediments to toxicity i...

30

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

SciTech Connect

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

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

1995-08-01

31

Texture development in naturally compacted and experimentally deformed silty clay sediments from the Nankai Trench and Forearc, Japan  

NASA Astrophysics Data System (ADS)

The petrophysical properties of fine-grained marine sediments to a large extent depend on the microstructure and crystallographic preferred orientations (CPOs). In this contribution we show that Rietveld-based synchrotron texture analysis is a new and valuable tool to quantify textures of water-saturated fine-grained phyllosilicate-rich sediments, and assess the effects of compaction and tectonic deformation. We studied the CPO of compositionally almost homogeneous silty clay drillcore samples from the Nankai Accretionary Prism slope and the incoming Philippine Sea plate, offshore SW Japan. Basal planes of phyllosilicates show bedding-parallel alignment increasing with drillhole depth, thus reflecting progressive burial and compaction. In some samples calcite and albite display a CPO due to crystallographically controlled non-isometric grain shapes, or nannofossil tests. Consolidated-undrained experimental deformation of a suite of thirteen samples from the prism slope shows that the CPOs of phyllosilicate and calcite basal planes develop normal to the experimental shortening axis. There is at least a qualitative relation between CPO intensity and strain magnitude. Scanning electron micrographs show concurrent evolution of preferred orientations of micropores and detrital illite flakes normal to axial shortening. This indicates that the microfabrics are sensitive strain gauges, and contribute to anisotropic physical properties along with the CPO.

Schumann, Kai; Stipp, Michael; Leiss, Bernd; Behrmann, Jan H.

2014-12-01

32

SAND REPORT SAND2002xxxx  

E-print Network

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

Newman, Alantha

33

Mystery Sand  

NSDL National Science Digital Library

In this activity, learners play with surprising sand that doesn’t get wet! Learners explore how water behaves differently when it comes in contact with "magic sand" and regular sand. Learners learn about the hydrophobic properties of "magic sand." Use this activity to talk about how many materials behave differently at the nanoscale.

2012-06-08

34

Benthic Bacterial Production and Protozoan Predation in a Silty Freshwater Environment  

Microsoft Academic Search

The interrelation of heterotrophic bacteria with bacterivorous protists has been widely studied in pelagic environments, but data on benthic habitats, especially in freshwater systems, are still scarce. We present a seasonal study focusing on bacterivory by heterotrophic nanoflagellates (HNF) and ciliates in the silty sediment of a temperate macrophyte-dominated oxbow lake. From January 2001 to February 2002 we monitored the

C. Wieltschnig; U. R. Fischer; A. K. T. Kirschner; B. Velimirov

2003-01-01

35

Use of Sequential Extraction in the Study of Heavy Metal Retention by Silty Soils  

Microsoft Academic Search

This study focused on the capability of two silty soils (tills) having low clay contents and CEC to retain and release two heavy metals, Pb and Cu. Samples of two non contaminated till deposits from the Eastern Townships region of Quebec, Canada, were artificially contaminated with concentrated solutions of these heavy metals. The latter were later extracted from the various

Alexandre R. Cabral; Guy Lefebvre

1998-01-01

36

Sand Storage  

USGS Multimedia Gallery

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

37

Sand Volcano Following Earthquake  

NASA Technical Reports Server (NTRS)

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

1989-01-01

38

Preliminary risk assessment of the wet landscape option for reclamation of oil sands mine tailings: bioassays with mature fine tailings pore water.  

PubMed

Chemical and biological assays have been carried out on the "pore water" that results from the settling of the tailings that accompany bitumen recovery from the Athabasca oil sands. Examination of the nonacidic extracts of pore water by gas chromatography-mass spectroscopy allowed the identification of numerous two- to three-ring polycyclic aromatic compounds (PACs), to a total concentration of 2.6 micrograms/L of pore water. The PACs were biodegraded by microflora naturally present in the pore water. Acute toxicity was associated principally with the acidic fraction (naphthenic acids) of pore water extracts according to the Microtox assay; other work has shown that acute toxicity dissipates fairly rapidly. Both individual PACs and concentrated pore water extracts showed minimal levels of binding to the rat Ah receptor and induced minimal ethoxyresorufin-O-deethylase activity in primary rat hepatocytes, showing an insignificant risk of inducing monooxygenase activity. Taken together with previous work showing negligible mutagenic activity of these extracts, we conclude that it should be possible to develop tailing slurries into biologically productive artificial lakes. PMID:11409191

Madill, R E; Orzechowski, M T; Chen, G; Brownlee, B G; Bunce, N J

2001-06-01

39

Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea  

USGS Publications Warehouse

Gas hydrate saturations were estimated using five different methods in silt and silty clay foraminiferous sediments from drill hole SH2 in the South China Sea. Gas hydrate saturations derived from observed pore water chloride values in core samples range from 10 to 45% of the pore space at 190-221 m below seafloor (mbsf). Gas hydrate saturations estimated from resistivity (Rt) using wireline logging results are similar and range from 10 to 40.5% in the pore space. Gas hydrate saturations were also estimated by P wave velocity obtained during wireline logging by using a simplified three-phase equation (STPE) and effective medium theory (EMT) models. Gas hydrate saturations obtained from the STPE velocity model (41.0% maximum) are slightly higher than those calculated with the EMT velocity model (38.5% maximum). Methane analysis from a 69 cm long depressurized core from the hydrate-bearing sediment zone indicates that gas hydrate saturation is about 27.08% of the pore space at 197.5 mbsf. Results from the five methods show similar values and nearly identical trends in gas hydrate saturations above the base of the gas hydrate stability zone at depths of 190 to 221 mbsf. Gas hydrate occurs within units of clayey slit and silt containing abundant calcareous nannofossils and foraminifer, which increase the porosities of the fine-grained sediments and provide space for enhanced gas hydrate formation. In addition, gas chimneys, faults, and fractures identified from three-dimensional (3-D) and high-resolution two-dimensional (2-D) seismic data provide pathways for fluids migrating into the gas hydrate stability zone which transport methane for the formation of gas hydrate. Sedimentation and local canyon migration may contribute to higher gas hydrate saturations near the base of the stability zone. Copyright 2011 by the American Geophysical Union.

Wang, X.; Hutchinson, D.R.; Wu, S.; Yang, S.; Guo, Y.

2011-01-01

40

Elastic properties of unconsolidated porous sand reservoirs  

Microsoft Academic Search

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

S. N. Domenico

1977-01-01

41

Bromide transport in a sandy and a silty soil - a comparative lysimeter study  

NASA Astrophysics Data System (ADS)

The aim of this study was a comparison of bromide leaching through a silty and a sandy soil and the characterization of systematic differences in solute transport in these undisturbed soils of differing texture. The amount of seepage water and bromide concentrations in the water were measured in 5 lysimeters for each soil type for a period of 460 days. Additionally, meteorological data were measured next to the lysimeter station for this period. The water transport regime of the lysimeters was simulated by means of a numerical solution of the Richards equation using the software package HYDRUS 1D. The observed bromide transport was simulated by steady-state approximation, applying the simulation tool CXTFIT, which is implemented in the software package STANMOD, version 2.0. Analysis of the measured data showed that a correct reproduction of the water balance was possible, but required the adaptation of soil-dependent crop coefficients for the potential transpiration of Phacelia and Winter Rape. The mean bromide transport through the sandy soil could be approximately reproduced assuming a bromide uptake by plants. Observed double peaks of some of the individual breakthrough curves, however, indicated that the actual transport regime in the lysimeters was subject to local heterogeneity which cannot be covered by the effective one-dimensional transport model. Bromide transport through the silty soil showed an unexplained mass deficit of nearly 90 % of the applied bromide and the detection of a mean distinct bromide peak in seepage water after percolation of only 0.5 pore volumes. It was not possible to simulate this behaviour with an effective 1D equilibrium or nonequilibrium convection-dispersion model.

Schober, L.; Iden, S. C.; Durner, W.

2009-04-01

42

Tar sands  

SciTech Connect

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

Wennekers, J.H.N.

1981-10-01

43

Contrasting hydrological and mechanical properties of clayey and silty muds cored from the shallow Nankai Trough accretionary prism  

E-print Network

Nankai Trough accretionary prism Miki Takahashi a , Shuhei Azuma b,1 , Shin-ichi Uehara c , Kyuichi January 2013 Keywords: Clayey mud Silty mud Nankai Trough accretionary prism Permeability Failure strength Friction Two mud samples cored from the shallow (1000 mbsf) Nankai Trough accretionary prism at Site C0002

Kanagawa, Kyuichi

44

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

USGS Publications Warehouse

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

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

2007-01-01

45

Musical Sands  

Microsoft Academic Search

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

J. H. Poynting

1908-01-01

46

Modelling chemical and biological reactions during unsaturated flow in silty arable soils  

NASA Astrophysics Data System (ADS)

Ion dynamics in arable soils are strongly affected by the chemical and biological transformations triggered by fertilizer input. Hydrogeochemical models may improve our understanding of underlying processes. Our objective was to test the ability of the hydrogeochemical model PHREEQC2 in combination with the parameter optimization programme PEST to describe and predict chemical and biological processes in silty soils triggered by fertilizer application or acidification and to investigate the usefulness of different parameterization approaches. Three different experiments were carried out using undisturbed columns of two topsoils (0-25 cm) from Germany (Göttingen, GO) and from the Oman (Qasha', QA). The columns were irrigated at 10 oC with 3 mm day-1 for one year using 1 mM HCl (HCl experiment) and two fertilizer solutions with low (0.1 to 0.9 mmol L-1) and high concentrations (1.3 to 14.7 mmol L-1) of N (as NH4NO3), K, Ca and Mg. In the fertilization experiments (Fert1, Fert2), the columns were alternately irrigated with the two different solutions for variable time periods. One-dimensional transport and homogenous and heterogenous reactions were calculated using PHREEQC2. The Fert1 experiment was used for calibration. The models were validated using the Fert2 and HCl experiments. The models tested were model variant m1 with no adjustable parameters, model variant m2 in which nitrate concentrations in input solutions and cation exchange capacity were optimized for Fert1, and m3 in which additionally all cation exchange coefficients and ion concentrations in the initial solution were optimized. Model variant m1 failed to predict the concentrations of several cations for both soils (modelling efficiencies (EF) ? 0), since N dynamics were not considered adequately. Model variants m2 and m3 described (Fert1 treatment) and predicted (Fert2 and HCl treatment) pH, cation and NO3- concentrations generally more accurately for both soils. For nutrient cations, EF values for prediction for GO ranged from 0.44 (K) to 0.99 (Ca), for QA from 0.21 (K) to 0.96 (Ca). After optimization, PHREEQC2 was able to predict NO3- concentrations in both soils (EF ? 0.57). Model variant m3 indicated that between 54 (QA) and 72 % (GO) of the exchange sites were involved in cation exchange reactions. Our results show the importance of the inclusion of nitrogen species when modelling cation dynamics in arable soils from different climate regions. The hydrogeochemical model PHREEQC2 in combination with PEST was useful to describe and predict ion dynamics in silty soils under unsaturated conditions.

Michel, Kerstin; Herrmann, Sandra; Ludwig, Bernard

2010-05-01

47

Infiltration capacity and macroporosity of a silty-loamy soil under different tillage systems  

NASA Astrophysics Data System (ADS)

For soils under both agricultural and forest use, management and tillage practice have significant influence on different hydraulic properties. Under agricultural land use, the properties of the macropore system are, amongst others, a function of the applied management and tillage system (i.e. conventional vs. conservation tillage). Macropores are crucial to rapid infiltration of surface water and aeration of the soil. Low macroporosity will give rise to higher surface flow rates especially on sloping areas, thus enhancing the risk for higher erosion. Investigations were carried out near the town of Adenstedt (52^o00', 9^o56'), app. 50 km S of Hannover in Lower Saxony. The predominant soil in the study area is an eroded orthic Luvisol from glacial deposits with a predominant silty-loamy texture. The experimental site with two crop rotations has been run with two different tillage systems (e.g. conventional and conservative tillage) since 1990. In this study, the minimum radius of a macropore is set to r = 0.5 cm. Dye tracer experiments were performed with methylene blue that was sprayed on a confined irrigation plot. Staining patterns were recorded two hours later at defined depth increments and results of stained and unstained areas were manually digitized and processed with an appropriate GIS-software. Tension infiltrometer experiments were performed simultaneously with the dye tracer experiments using a tension infiltrometer (hood infiltrometer) at different hydraulic supply potentials and soils depths. Dye tracer experiments with methylene blue indicate a penetration depth of 120 cm on the reduced tilled plot as compared to the conventionally tilled plot (60 cm). Both tillage systems exhibit the highest density of macropores in the topsoil, ranging between 100 and 1.000 macropores per square meter. The conventionally tilled plot exhibits a higher number of macropores in the upper 20 cm than the reduced tilled plot while at greater soil depth, this holds true for the reduced tiled plot. Macroporosity derived from tension infiltrometer experiments yield results about one order of magnitude lower than those obtained by visual inventarization. The results indicate a greater continuity of vertically oriented macropores for soils with reduced tillage systems. Thus, in the context of a more effective prevention of flooding events in watersheds, tillage practices with reduced soil disturbance offer a means to decrease surface runoff by enhancing vertical drainage in agricultural areas with silty soils. However, the effect of this local-scale soil hydraulic property on the hydrological behavior on the scale of whole watersheds on the mesoscale (100--500 km^2) needs yet to be tested by simulations with physically based hydrological models.

Wahl, N. A.; Buczko, U.; Bens, O.; Hüttl, R. F.

2003-04-01

48

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

USGS Publications Warehouse

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

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

1998-01-01

49

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

Microsoft Academic Search

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

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

1998-01-01

50

Water content, porosity and cement content as parameters controlling strength of artificially cemented silty soil  

Microsoft Academic Search

Present study aims to assess the strength controlling parameters of a fine grained soil molded at three distinct water contents considering four distinctive cement amounts and three distinguishing dry unit weights to show that the effect of diverse soil structures formed during compaction of fine grained soils at distinct water contents, the porosity of the specimens and the amount of

Nilo Cesar Consoli; Daniela Aliati Rosa; Rodrigo Caberlon Cruz; Amanda Dalla Rosa

2011-01-01

51

Effect of puddling intensity on physical properties of a silty clay soil under laboratory and field conditions  

Microsoft Academic Search

Conventional tillage and planting method for rice (Oryza sativa L.) production in northern Iran is wet tillage (puddling). Effect of different puddling intensities on physical properties\\u000a of a silty clay soil (Typic Haplodalfs) was investigated under laboratory and field conditions. Changes in soil physical parameters\\u000a and water requirement for puddling were measured. For laboratory experiments, undisturbed cylindrical soil samples (diameter

S. F. Mousavi; S. Yousefi-Moghadam; B. Mostafazadeh-Fard; A. Hemmat; M. R. Yazdani

2009-01-01

52

Benthic bacterial production and protozoan predation in a silty freshwater environment.  

PubMed

The interrelation of heterotrophic bacteria with bacterivorous protists has been widely studied in pelagic environments, but data on benthic habitats, especially in freshwater systems, are still scarce. We present a seasonal study focusing on bacterivory by heterotrophic nanoflagellates (HNF) and ciliates in the silty sediment of a temperate macrophyte-dominated oxbow lake. From January 2001 to February 2002 we monitored the standing stock of bacteria and protozoa, bacterial secondary production (BSP, (3)H-thymidine, and (14)C-leucine incorporation), and grazing rates of HNF and ciliates on bacteria (FLB uptake) in the oxic sediment of the investigated system. BSP ranged from 470 to 4050 micro g C L(-1) wet sediment h(-1). The bacterial compartment turned out to be highly dynamic, indicated by population doubling times (0.6-10.0 d), which were comparable to those in the water column of the investigated system. Yet, the control mechanisms acting upon the bacterial population led to a relative constancy of bacterial standing stock during a year. Ingestion rates of protozoan grazers were 0-20.0 bacteria HNF(-1) h(-1) and 0-97.6 bacteria ciliate(-1) h(-1). HNF and ciliates together cropped 0-14 (mean 4)% of BSP, indicating that they did not significantly contribute to benthic bacterial mortality during any period of the year. The low impact of protozoan grazing was due to the low numbers of HNF and ciliates in relation to bacteria (1.8-3.5 x 10(4) bacteria HNF(-1), 0.9-3.1 x 10(6) bacteria ciliate(-1)). Thus, grazing by HNF and ciliates could be ruled out as a parameter regulating bacterial standing stock or production in the sediment of the investigated system, but the factors responsible for the limitation of benthic protistan densities and the fate of benthic BSP remained unclear. PMID:12739079

Wieltschnig, C; Fischer, U R; Kirschner, A K T; Velimirov, B

2003-07-01

53

An experimental study on the wave-induced pore water pressure change and relative influencing factors in the silty seabed  

NASA Astrophysics Data System (ADS)

In this study, a flume experiment was designed to investigate the characteristics of wave-induced pore water pressure in the soil of a silty seabed with different clay contents, soil layer buried depths and wave heights respectively. The study showed that water waves propagating over silty seabed can induce significant change of pore water pressure, and the amplitude of pore pressure depends on depth of buried soil layer, clay content and wave height, which are considered as the three influencing factors for pore water pressure change. The pressure will attenuate according to exponential law with increase of soil layer buried depth, and the attenuation being more rapid in those soil layers with higher clay content and greater wave height. The pore pressure in silty seabed increases rapidly in the initial stage of wave action, then decreases gradually to a stable value, depending on the depth of buried soil layer, clay content and wave height. The peak value of pore pressure will increase if clay content or depth of buried soil layer decreases, or wave height increases. The analysis indicated that these soils with 5% clay content and waves with higher wave height produce instability in bed easier, and that the wave energy is mostly dissipated near the surface of soils and 5% clay content in soils can prevent pore pressure from dissipating immediately.

Li, Anlong; Luo, Xiaoqiao; Lin, Lin; Ye, Qing; Le, Chunyu

2014-12-01

54

Transport of fine sediment over a coarse, immobile riverbed  

USGS Publications Warehouse

Sediment transport in cobble-boulder rivers consists mostly of fine sediment moving over a coarse, immobile bed. Transport rate depends on several interrelated factors: boundary shear stress, the grain size and volume of fine sediment, and the configuration of fine sediment into interstitial deposits and bed forms. Existing models do not incorporate all of these factors. Approaches that partition stress face a daunting challenge because most of the boundary shear is exerted on immobile grains. We present an alternative approach that divides the bed into sand patches and interstitial deposits and is well constrained by two clear end-member cases: full sand cover and absence of sand. Entrainment from sand patches is a function of their aerial coverage. Entrainment from interstices among immobile grains is a function of sand elevation relative to the size of the immobile grains. The bed-sand coverage function is used to predict the ratio of the rate of entrainment from a partially covered bed to the rate of entrainment from a completely sand-covered bed, which is determined using a standard sand transport model. We implement the bed-sand coverage function in a morphodynamic routing model and test it against observations of sand bed elevation and suspended sand concentration for conditions of nonuniform fine sediment transport in a large flume with steady uniform flow over immobile hemispheres. The results suggest that this approach may provide a simple and robust method for predicting the transport and migration of fine sediment through rivers with coarse, immobile beds.

Grams, Paul E.; Wilcock, Peter R.

2014-01-01

55

Industrial sand and gravel  

USGS Publications Warehouse

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

Dolley, T.P.

2011-01-01

56

Estimating Particle-Size Distribution from Sand, Silt, and Clay Content  

NASA Astrophysics Data System (ADS)

Particle-size distribution (PSD) is one of the soil properties which not only is used in estimation of soil water retention curve as well as unsaturated hydraulic conductivity, but also is applied in the most hydrological studies. Since the measurement of particle-size distribution, soil water retention curve and unsaturated hydraulic conductivity is time consuming and expensive especially in large scale hydrological investigations, in this study, a method was developed based upon the least squares optimization approach to estimate cumulative particle-size distribution from sand, silt and clay content. A revised form of van Genuchten retention model which has been previously applied to represent cumulative particle-size distribution was fitted to the measured three points of PSD, and its two unknown parameters such as N and Dg were determined. For this purpose, we used curve fitting toolbox of MATLAB software. Then estimated N and Dg values were applied to estimate cumulative particle mass for other particle radii in order to determine the whole shape of PSD. A total of 80 soil samples from the UNSODA database including 10 soil textures were selected to verify the presented method. We divided our database into three groups, (1) is coarse soil texture including sand, sandy loam and loamy sand (32 soil samples), (2) medium soil texture such as sandy clay loam, loam, silt loam (31 soil samples), and (3) fine soil texture including clay, sandy clay, silty clay and clay loam (17 soil samples). The RMSE value was calculated to evaluate the presented method. For groups 1, 2 and 3, the RMSE values were 0.071, 0.064, and 0.046, respectively. The linear regression between the estimated and measured cumulative particle mass showed that this method is capable for estimating PSD from three measured points. The line slope for groups 1, 2 and 3 were 0.93, 0.94 and 0.95, respectively, and correlation coefficient (R2) values were obtained greater than 0.96. For all 80 soil samples, the RMSE, R2 and line slope values were 0.062, 0.97 and 0.94 indicating the proposed method estimated PSD accurately. Acknowledgements The authors would like to acknowledge Dr. M.Th. van Genuchten for providing the UNSODA database used in this study.

Roostaee, Maryam; Ghanbarian-Alavijeh, Behzad; Liaghat, Abdolmajid

2010-05-01

57

Tar sand  

SciTech Connect

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

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

1990-01-01

58

SAND REPORT SAND2003-0112  

E-print Network

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

Fuerschbach, Phillip

59

Sand particle dislodgement in windblown sand  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

60

The extraction of bitumen from western tar sands. Annual report  

SciTech Connect

Topics discussed include: characterization of bitumen impregnated sandstone, water based tar sand separation technology, electrophoretic characterization of bitumen and fine mineral particles, bitumen and tar sand slurry viscosity, the hot water digestion-flotation process, electric field use on breaking water-in-oil emulsions, upgrading of bitumens and bitumen-derived liquids, solvent extraction.

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

1990-07-01

61

The extraction of bitumen from western tar sands  

SciTech Connect

Topics discussed include: characterization of bitumen impregnated sandstone, water based tar sand separation technology, electrophoretic characterization of bitumen and fine mineral particles, bitumen and tar sand slurry viscosity, the hot water digestion-flotation process, electric field use on breaking water-in-oil emulsions, upgrading of bitumens and bitumen-derived liquids, solvent extraction.

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

1990-07-01

62

Oil sands tailings sludge solidification and bitumen recovery  

Microsoft Academic Search

Canada is a forerunner in the development of oil sands mining and processing technology. At present two commercial plants, both of them surface mining operations are producing approximately 200,000 of syncrude per day. At both of these plants a hot water separation process is used.The vast amounts of tailings, consisting of bitumen, sand, fines and water, generated from the hot

B. D. Prasad Head

1988-01-01

63

Wind tunnel measurements of adobe abrasion by blown sand: profile characteristics in relation to wind velocity and sand flux  

Microsoft Academic Search

Blown sand causes various damages, such as extensive abrasion to crops, structural wear of facilities and buildings, and abrasion of soil clods and clayey materials generating fine particulate matter. In this study, experiments conducted in a straight-line blowing wind tunnel confirmed field observations and provided useful information for understanding abrasion profiles created by sand drift. Abrasion rates of 20 adobe

Liu Lian-You; Gao Shang-Yu; Shi Pei-Jun; Li Xiao-Yan; Dong Zhi-Bao

2003-01-01

64

Creating Sand Dunes  

NSDL National Science Digital Library

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

1998-01-01

65

Industrial sand and gravel  

USGS Publications Warehouse

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

Dolley, T.P.

2012-01-01

66

Industrial sand and gravel  

USGS Publications Warehouse

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

Dolley, T.P.

2013-01-01

67

Tar sand evaluation using geophysical well logs  

Microsoft Academic Search

Geophysical well logging can provide a record of the lithological variations and oil yield of tar sands. Probes lowered into bore holes at the end of insulated cables yield such records as the spontaneous potential log, the focused resistivity log, the gamma-ray log, the acoustic log and the neutron log. The accuracy of correlations between gamma-ray log response and fines

WALTER H. FERTL; GEORGE V. CHILINGARIAN

1978-01-01

68

Provenance, areal distribution, and contemporary sedimentation of quartz sand and silt types on the mid-atlantic continental shelf  

E-print Network

, except in the cases of Delaware Bay and Albemarle Sound where this silt is restricted to the bay area. 54 DISCUSSION The surficial sediment on the Hid-Atlantic continental shelf contains two distinct quartz grain shape types in the fine sand... will be referred to as montane sediment. Distribution of Fine Sand High proportions of montane sand are found in the modern fluvial and estuarine deposits of Albemarle Sound, Chesapeake Bay, and Hudson Bay (Figure 12). The montane sand is also present...

Prusak, Deanne

2012-06-07

69

Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico  

Microsoft Academic Search

A unique set of high-quality downhole shallow subsurface well log data combined with industry standard 3D seismic data from the Alaminos Canyon area has enabled the first detailed description of a concentrated gas hydrate accumulation within sand in the Gulf of Mexico. The gas hydrate occurs within very fine grained, immature volcaniclastic sands of the Oligocene Frio sand. Analysis of

Ray Boswell; Dianna Shelander; Myung Lee; Tom Latham; Tim Collett; Gilles Guerin; George Moridis; Matthew Reagan; Dave Goldberg

2009-01-01

70

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

Microsoft Academic Search

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

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

2003-01-01

71

Vertebrate Tracks in Pleistocene Eolian Sand-Sheet Deposits of Alaska  

NASA Astrophysics Data System (ADS)

Deformation structures interpreted as vertebrate hoof- and foot-tracks occur within upper-Pleistocene eolian sand-sheet deposits in the stabilized Kantishna sand sea of central Alaska and in the Nushagak lowland of southwestern Alaska. Exposures of tracks are generally limited to cross sections, which reveal concave-up deformation structures in which displacement of preexisting strata diminishes downward. Deposits in both areas contain tracks that are 6 to 16 cm in diameter and are divided by a central ridge, reflecting formation by artiodactyl (even-toed) ungulates. Larger (21-34 cm) tracks without a central ridge, observed in the Nushagak lowland, were formed by proboscideans, probably woolly mammoth. Large vertebrate tracks occur within irregularly stratified sand and silty sand that accumulated upon partially vegetated sand sheets, and within thin, even wind-ripple laminae of unvegetated sand sheets. The presence of tracks at multiple stratigraphic levels and preservation of roots and rhizocretions within the eolian deposits suggest that vegetated sand sheets may have formed a locally important grazing habitat for large herbivores during at least part of the last glaciation. Recognition that vertebrate tracks are preserved in eolian sand-sheet deposits, and in deposits of other environments as well, opens a new source of stratigraphic and paleoecological data to aid reconstruction of the vanished ecosystems of Beringia.

Lea, Peter D.

1996-03-01

72

Critical State of Sand Matrix Soils  

PubMed Central

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

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

2014-01-01

73

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

Microsoft Academic Search

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

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

1999-01-01

74

CONTRACTOR REPORT SAND927005  

E-print Network

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

75

Mineral Sands Down Under  

NSDL National Science Digital Library

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

76

Exploring Products: Nano Sand  

NSDL National Science Digital Library

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

2014-06-16

77

Sand for Traction  

USGS Multimedia Gallery

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

78

MIXTURES OF FINE-GRAINED MINERALS KAOLINITE AND CARBONATE GRAINS  

E-print Network

; Carman, 1937; White and Walton, 1937; German, 1989), while mixtures of rounded sand and platy mica grains without mica (Guimaraes, 2002). Mixtures of fine and coarse grains exhibit unique behavior, often related

Palomino, Angelica M.

79

Industrial sand and gravel  

USGS Publications Warehouse

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

Dolley, T.P.

2006-01-01

80

The Effect of the Kind of Sands and Additions on the Mechanical Behaviour of S.C.C  

NASA Astrophysics Data System (ADS)

The sand is an inert element essential in the composition of concrete; its use ensures granular continuity between the cement and gravel for better cohesion of concrete. This paper presents the results of a study that investigated the influence of sand quality on the properties of fresh and hardened self-compacting concrete (SCC). The dune sands are very fine materials characterized by a high intergranular porosity, high surface area and low fineness modulus; on the other hand crushed (manufactured) sand has a high rate into thin and irregular shapes which are influencing the workability of concrete. The amount of dune sand varies from (0% 50%, to 100%) by weight of fine aggregates. The effect of additions is also treated (blast furnace slag and lime stone) The results show that the rheological properties favour the use of dune sands; however the mechanical properties support the use of crushed sand.

Zeghichi, L.; Benghazi, Z.; Baali, L.

81

Process and apparatus for recovery of oil from tar sands  

SciTech Connect

A crude oil product is extracted from a tar sand by first crushing the tar sand as mined and then fine grinding the crushed material in a grinding mill in the presence of a cleansing liquid, such as an aqueous solution of a caustic. The resulting slurry is passed into suitable extractor-classifier equipment, such as that shown in U.S. Pat. No. 3,814,336, in which a body of cleansing liquid is maintained. Agitation of the slurry in such maintained body of cleansing liquid substantially completes removal of the bituminous matter from the sand, and the resulting crude oil and cleansing liquid phase is discharged separately from the sand solid phase. The liquid phase is treated for the removal of residual sand particles and for the separation of residual cleansing liquid from the crude oil. The cleansing liquid so recovered is recycled and the crude oil is passed to further processing or for use as such.

Brewer, J.C.

1982-11-30

82

Fine Travel  

NSDL National Science Digital Library

FineTravel Magazine, produced by Louis Bignami and Big-Ray Publications, is a webzine aimed "at the traveler, not the tourist." It contains first person account feature articles about interesting nooks and crannies of various travel destinations in the US and around the world. Updated weekly, it features a searchable and browsable archive of past FineTravel articles, as well as pointers to airline information, books and videos, and resorts. It is an informative and entertaining site for the Internaut interested in travel.

1995-01-01

83

Fine Arts.  

ERIC Educational Resources Information Center

Discusses the use of fine arts as sources to enrich the study of history. Suggests that such works will serve as barometers of change, examples of cross-cultural influences, and political messages. Includes suggestions of works and artists from different historic periods. (DK)

Danzer, Gerald A.; Newman, Mark

1992-01-01

84

Permeability of shaly sands  

NASA Astrophysics Data System (ADS)

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

Revil, A.; Cathles, L. M.

1999-03-01

85

Effects of deposit-feeding macrofauna on benthic bacteria, viruses, and protozoa in a silty freshwater sediment.  

PubMed

In microcosm experiments, we simultaneously tested the effects of increased numbers of deposit-feeding macrofauna (chironomids, oligochaetes and cladocerans) on the standing stock, activities and interactions of heterotrophic bacteria, viruses, and bacterivorous protozoa (heterotrophic nanoflagellates and ciliates) in the aerobic layer of a silty littoral freshwater sediment. On average, bacterial secondary production was stimulated between 11 and 29% by all macrofaunal groups compared to control experiments without macrofauna addition. Bacterial standing stock increased significantly by 8 and 13% in case of chironomids and cladocerans, respectively. Oligochaetes and chironomids produced significant negative effects on viral abundance while the results with cladocerans were inconsistent. The addition of oligochaetes and chironomids resulted in a significant decrease by on average 68 and 32% of viral decay rates, respectively, used as a measure of viral production. The calculated contribution of virus-induced lysis to benthic bacterial mortality was low, with 2.8 to 11.8% of bacterial secondary production, and decreased by 39 to 81% after the addition of macrofauna compared to the control. The abundances of heterotrophic nanoflagellates were significantly reduced by 20% by all tested macrofauna groups, while ciliates showed inconsistent results. The importance of heterotrophic nanoflagellate grazing on benthic bacteria was very low (<1% of bacterial secondary production) and was further reduced by elevated numbers of macrofauna. Thus, the selected deposit feeding macrofauna groups seem to have several direct and indirect and partly antagonistic effects on the benthic bacterial compartment through the enhancement of bacterial production and the reduction of virus-induced cell lysis and protozoan grazing. PMID:17876654

Wieltschnig, Claudia; Fischer, Ulrike R; Velimirov, Branko; Kirschner, Alexander K T

2008-07-01

86

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

SciTech Connect

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

Olson, H.C.

1986-04-01

87

Industrial sand and gravel  

USGS Publications Warehouse

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

Dolley, T.P.

2010-01-01

88

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

E-print Network

river Sand-bed Channel characteristics Great Plains Hydraulic geometry Downstream trends in hydraulic reaches. Sediment analyses demonstrated a significant trend in downstream fining of surface grain-sizes (D90 and D50) but unlike previous studies of sand-bedded rivers we observed coarsening of substrates

Gido, Keith B.

89

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

Microsoft Academic Search

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

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

90

Sand, Plants and Pants  

NSDL National Science Digital Library

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

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

2014-06-04

91

Sand boils without earthquakes  

USGS Publications Warehouse

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

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

1993-01-01

92

Sand on the Move  

NSDL National Science Digital Library

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

93

North Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

94

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...

95

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

SciTech Connect

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

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

1994-04-01

96

Prediction of compressive strength of concrete with fly ash as sand replacement material  

Microsoft Academic Search

Fly ash (FA) acts as a partial replacement material for both Portland cement and fine aggregate. The published information on FA as sand (fine aggregate) replacement material (SRM) is limited and rational guidelines to estimate the compressive strength of concrete are not available. This aspect was investigated and a formula to predict the compressive strength of concrete at 28day is

N. P. Rajamane; J. Annie Peter; P. S. Ambily

2007-01-01

97

Frosted Sand Dunes  

NASA Technical Reports Server (NTRS)

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

2002-01-01

98

Ganges Chasma Sand Sheet  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

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

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

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

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

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

2005-01-01

99

Asbestos in play sand  

SciTech Connect

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

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

1987-04-02

100

Sand Dunes with Frost  

NASA Technical Reports Server (NTRS)

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

2004-01-01

101

Windblown Sand in Briault  

NASA Technical Reports Server (NTRS)

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

2004-01-01

102

Sand Hill Rd. Junipero Serra  

E-print Network

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

Stanford University

103

Sand and sandstone  

SciTech Connect

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

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

1987-01-01

104

Northern Sand Sea  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

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

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

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

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

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

2005-01-01

105

Sound-Producing Sand Avalanches  

Microsoft Academic Search

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

Paul Sholtz; Michael Bretz; Franco Nori

1996-01-01

106

Determination of fine-scale vertical distribution of microbes and meiofauna in an intertidal sediment  

Microsoft Academic Search

A simple sampling device is described which produces thin (1 mm) sections of sediment cores. The sampler has been tested on fine sand of an intertidal sandflat and used to study the vertical distribution, over part of a tidal cycle in August, 1981, of migrating algae in the surface 20 mm of sand. Two species of Diplonies and one of

I. R. Joint; J. M. Gee; R. M. Warwick

1982-01-01

107

Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

108

Dark Sand Dunes  

NASA Technical Reports Server (NTRS)

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

2005-01-01

109

Moving sand dunes  

E-print Network

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

Sparavigna, Amelia Carolina

2011-01-01

110

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

NASA Astrophysics Data System (ADS)

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

Benaafi, Mohammed; Abdullatif, Osman

2014-05-01

111

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

SciTech Connect

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

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

1997-11-26

112

Assessment of the KE Basin Sand Filter Inventory In Support of Hazard Categorization  

SciTech Connect

In 1978, the water cleaning system for the KE Basin was upgraded by adding a sand filter and ion exchange columns. Basin water containing finely divided solids is collected by three surface skimmers and pumped to the sand filter. Filtrate from the sand filter is further treated in the ion exchange modules. The suspended solids accumulate in the sand until the pressure drop across the filter reaches established operating limits, at which time the sand filter is backwashed. The backwash is collected in the NLOP, where the solids are allowed to settle as sludge. Figure 2-1 shows a basic piping and instrumentation diagram depicting the relationship among the basin skimmers, sand filter, and NLOP. During the course of deactivation and decommissioning (D&D) of the K-Basins, the sand filter and its media will need to be dispositioned. The isotopic distribution of the sludge in the sand filter has been estimated in KE Basin Sand Filter Monolith DQO (KBC-24705). This document estimates the sand filter contribution to the KE hazard categorization using the data from the DQO.

Ross, Steven B.; Young, Jonathan

2005-09-28

113

Sand as a relevant fraction in geochemical studies in intertidal environments.  

PubMed

Soil and sediment samples from several intertidal environment exposed to different types of contamination were studied to investigate the importance of grain size in relation to the capacity of the substrates to retain trace metals. The unfractionated samples (referred to as bulk samples) were separated into the following grain/size fractions: fine-coarse sand (2-0.100 mm), very fine sand (0.100-0.050 mm), silt (0.050-0.002 mm), and clay (0.002 mm). The sample into its fractions was carried out was in a glove box under high-purity N2 atmosphere in order to minimize any alterations to the samples. The bulk samples were characterized in terms of physicochemical properties such as pH, redox potential, and grain size. The total organic carbon (TOC), total sulfur (S), iron (Fe) pyrite, Fe, and manganese (Mn), and trace metals lead (Pb), mercury (Hg), chromium (Cr), and nickel (Ni) were analyzed in the bulk samples and in each fraction. The sand fractions were also examined by scanning electron microscopy (SEM). Comparisons of the above parameters were made between fractions and between each fraction and the corresponding bulk sample. The fine-coarse sand fraction contained high levels of the primary elements of the geochemical processes that occur in marine sedimentary environments such as TOC, total Fe, Mn, and S. The net concentrations of these four elements were higher in the fine-coarse sand fraction than in the very fine sand fraction and were similar to the net concentrations in the silt and clay fractions. Detailed SEM analysis of the sand coarse fraction revealed the presence of Fe and aluminum oxyhydroxide coatings in the oxic layers, whereas the framboidal pyrites and coatings observed in the anoxic layers were Fe sulfides. The presence of the various coatings explains why the trace metal concentrations in the sand fine-coarse fraction were similar to those in the clay fraction and higher than those in the very fine sand fraction. The present results highlight the importance of the sand fraction, which is generally disregarded in geochemical and environmental studies of sedimentary layers. PMID:23525774

Otero, X L; Huerta-Díaz, M A; De La Peña, S; Ferreira, T O

2013-10-01

114

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

NASA Astrophysics Data System (ADS)

Previously undescribed pollen, plant macrofossils, molluscs, and ostracodes were recovered from a 2.5-m-thick glaciolacustrine unit of silty sand and clay at Valders, Wisconsin. The interstadial sediment was deposited about 12,200 14C yr B.P. after retreat of the Green Bay lobe that deposited diamicton of the Horicon Formation, and before advance of the Lake Michigan lobe that deposited the red-brown diamicton of the Valders Member of the Kewaunee Formation. Fluctuations of abundance of Candona subtriangulata, Cytherissa lacustris,and three other species define four ostracode biozones in the lower 1.7 m, suggesting an open lake environment that oscillated in depth and proximity to glacial ice. Pollen is dominated by Piceaand Artemisia,but the low percentages of many other types of long-distance origin suggest that the terrestrial vegetation was open and far from the forest border. The upper part of the sediment, a massive sand deposited in either a shallow pond or a sluggish stream, contains a local concentration of plant macrofossils. The interpretation of a cold open environment is supported by the plant macrofossils of more than 20 species, dominated by those of open mineral soils ( Arenaria rubella, Cerastium alpinumtype, Silene acaulis, Sibbaldia procumbens, Dryas integrifolia, Vaccinium uliginosumvar. alpinum, Armeria maritima,etc.) that in North America occur largely in the tundra and open tundra-forest ecotone of northern Canada. Ice-wedge casts occur in the sand.

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

1998-03-01

115

Investigation of guided waves propagation in pipe buried in sand  

NASA Astrophysics Data System (ADS)

The inspection of pipelines by guided wave testing is a well-established method for the detection of corrosion defects in pipelines, and is currently used routinely in a variety of industries, e.g. petrochemical and energy. When the method is applied to pipes buried in soil, test ranges tend to be significantly compromised because of attenuation of the waves caused by energy radiating into the soil. Moreover, the variability of soil conditions dictates different attenuation characteristics, which in-turn results in different, unpredictable, test ranges. We investigate experimentally the propagation and attenuation characteristics of guided waves in pipes buried in fine sand using a well characterized full scale experimental apparatus. The apparatus consists of an 8 inch-diameter, 5.6-meters long steel pipe embedded over 3 meters of its length in a rectangular container filled with fine sand, and an air-bladder for the application of overburden pressure. Longitudinal and torsional guided waves are excited in the pipe and recorded using a transducer ring (Guided Ultrasonics Ltd). Acoustic properties of the sand are measured independently in-situ and used to make model predictions of wave behavior in the buried pipe. We present the methodology and the systematic measurements of the guided waves under a range of conditions, including loose and compacted sand. It is found that the application of overburden pressure modifies the compaction of the sand and increases the attenuation, and that the measurement of the acoustic properties of sand allows model prediction of the attenuation of guided waves in buried pipes with a high level of confidence.

Leinov, Eli; Cawley, Peter; Lowe, Michael J. S.

2014-02-01

116

Investigation of guided waves propagation in pipe buried in sand  

SciTech Connect

The inspection of pipelines by guided wave testing is a well-established method for the detection of corrosion defects in pipelines, and is currently used routinely in a variety of industries, e.g. petrochemical and energy. When the method is applied to pipes buried in soil, test ranges tend to be significantly compromised because of attenuation of the waves caused by energy radiating into the soil. Moreover, the variability of soil conditions dictates different attenuation characteristics, which in-turn results in different, unpredictable, test ranges. We investigate experimentally the propagation and attenuation characteristics of guided waves in pipes buried in fine sand using a well characterized full scale experimental apparatus. The apparatus consists of an 8 inch-diameter, 5.6-meters long steel pipe embedded over 3 meters of its length in a rectangular container filled with fine sand, and an air-bladder for the application of overburden pressure. Longitudinal and torsional guided waves are excited in the pipe and recorded using a transducer ring (Guided Ultrasonics Ltd). Acoustic properties of the sand are measured independently in-situ and used to make model predictions of wave behavior in the buried pipe. We present the methodology and the systematic measurements of the guided waves under a range of conditions, including loose and compacted sand. It is found that the application of overburden pressure modifies the compaction of the sand and increases the attenuation, and that the measurement of the acoustic properties of sand allows model prediction of the attenuation of guided waves in buried pipes with a high level of confidence.

Leinov, Eli; Cawley, Peter; Lowe, Michael J.S. [NDE Group, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

2014-02-18

117

Direct Shear Tests on Waste Tires–Sand Mixtures  

Microsoft Academic Search

Waste tires are used in some engineering applications and thereby reduce the potential impact on the environment, for example,\\u000a as lightweight materials in geotechnical engineering projects. This paper presents a brief literature review on geotechnical\\u000a applications of processed waste tires, and a laboratory study on the effect of tire shreds on the physical properties of two\\u000a different sands (fine angular

Ali Firat Cabalar

2011-01-01

118

Ganges Rocks and Sand  

NASA Technical Reports Server (NTRS)

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

2005-01-01

119

Sand Dunes in Hellas  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

120

Fortune Cookie Sand Dunes  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

121

Martian Sand Dunes  

NASA Technical Reports Server (NTRS)

6 January 2004

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

2005-01-01

122

The optimization of the formulation of sand dunes for road use  

NASA Astrophysics Data System (ADS)

The use of sand dunes of the Sahara in road construction is a very important economic interest because of its high availability and ease of extraction. However, these materials have, naturally, a very strong instability mainly due to the rounded shape of the grain and the absence of the fine fraction, which makes almost no cohesion. Apart from the classical formulas treatment with hydraulic binders, materials can be the value by a correction of the particle size of sand with the addition of materials consistent. Thus the possibility of using sand dunes mixed with natural clay, sand, limestone and tuff is proposed in this paper. The results show that the treatment of sand dunes by adding 30% of materials revealed three consistent resistance formulas, the best being the clay-based.

Saoula, Samia; Soudani, Khedoudja; Haddadi, Smail

2013-12-01

123

Recycling of PET bottles as fine aggregate in concrete.  

PubMed

An attempt to substitute in concrete the 5% by weight of fine aggregate (natural sand) with an equal weight of PET aggregates manufactured from the waste un-washed PET bottles (WPET), is presented. The WPET particles possessed a granulometry similar to that of the substituted sand. Specimens with different cement content and water/cement ratio were manufactured. Rheological characterization on fresh concrete and mechanical tests at the ages of 28 and 365days were performed on the WPET/concretes as well as on reference concretes containing only natural fine aggregate in order to investigate the influence of the substitution of WPET to the fine aggregate in concrete. It was found that the WPET concretes display similar workability characteristics, compressive strength and splitting tensile strength slightly lower that the reference concrete and a moderately higher ductility. PMID:20176466

Frigione, Mariaenrica

2010-06-01

124

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

NASA Astrophysics Data System (ADS)

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

Venditti, Jeremy G.; Church, Michael

2014-09-01

125

Science Learning in the Sand.  

ERIC Educational Resources Information Center

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

Sexton, Ursula

1997-01-01

126

Introduction Sand sole, Psettichthys melanostictus,  

E-print Network

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

127

Behaviour of Sand Reinforced with Fibres  

NASA Astrophysics Data System (ADS)

This study focuses on the effects of randomly oriented discrete crimped polypropylene fibres on the mechanical response of very fine sand. Compaction and direct shear tests were performed on sand specimens of different densities unreinforced and reinforced with fibres in different proportions. The presence of reinforcement provides an extra resistance to the compaction, causing a less dense packing as the quantity of fibres is increased. The results of the direct shear tests indicate that inclusion of fibres increases the peak shear strength and the strain required to reach the peak. The post-peak strength at large strains was also higher when fibres were included. The presence of fibres leads to more dilative behaviour. In this study, for the range of the effective normal stresses employed, a linear failure envelope has been recorded for all densities and fibre concentrations. The increase of the peak shear strength was almost linear for all densities at low effective normal stress and approached a limiting value for higher normal stresses. For the loosest specimens reinforced with the highest percentage of fibres that could be employed in the laboratory using a moist tamping fabrication method, the relative increase of the peak shear strength was more than 50%.

Ibraim, Erdin; Fourmont, Stephane

128

Sand pictures : what's missing?  

NSDL National Science Digital Library

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

National Council of Teachers of Mathematics (NCTM)

2002-01-01

129

Sand swimming lizard: sandfish  

E-print Network

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

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

2009-01-01

130

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

USGS Publications Warehouse

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

Nordin, Carl F.; Perez-Hernandez, David

1989-01-01

131

Unchanging Desert Sand Dunes  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

132

Optimization of the peroxy acid treatment of alpha-methylnaphthalene and benzo[a]pyrene in sandy and silty-clay sediments.  

PubMed

The majority of polycyclic aromatic hydrocarbons (PAHs) released to the environment come from anthropogenic sources involving the incomplete combustion of organic compounds. Several techniques are available for the degradation of PAHs. Among the abiotic/biotic processes used to degrade PAHs, an alternative strategy utilizing a primary chemical oxidative step to be combined with a biological was created. The degradation of alpha-methylnaphthalene and benzo[a]pyrene using an advanced oxidation process was optimized over a period of 24 h by varying the ratio of acetic acid to hydrogen peroxide, the compounds that form peroxy acids. The optimization process was performed using sandy and silty-clay sediment types. Gas chromatography equipped with a flame ionization detector was used to determine the varied rates of degradation depending on acetic acid:hydrogen peroxide ratios and the characteristics of the sediment sample. Reduction of 20-90% of alpha-methylnaphthalene and benzo[a]pyrene was observed when 2-5 mL of hydrogen peroxide was used, respectively. A peracetic acid solution (e.g., a commercial form of acetic acid and hydrogen peroxide) was used to compare the results from the peroxy acid experiments. In all the experiments, peracetic acid was more reactive than the combination of acetic acid and hydrogen peroxide. Acetic acid, deionized water, and hydrogen peroxide served as controls and demonstrated minimal degradation over the time course study. Therefore, the use of a peroxy acid process to target electron dense pollutants may have a great utility. PMID:15046359

N'Guessan, Adeola L; Carignan, Todd; Nyman, Marianne C

2004-03-01

133

Drainage in heterogeneous sand columns with different geometric structures  

NASA Astrophysics Data System (ADS)

This paper discusses multi-step drainage experiments in two heterogeneously packed sand columns (10 × 10 × 20 cm 3). Different packing structures were generated using two different sand types. One purpose of the study was to test the influence of packing structures on the movement of water. The second purpose was to assess the quality of predictions for the outflow curves in both columns made with an upscaled model. The heterogeneous structures of the columns can be considered as two opposing extremes. The first column was packed with a random arrangement of two sand types that is not stochastically homogeneous and where a cluster running through the column exists for both materials. The second column was packed with a periodic pattern of coarse-sand inclusions in a fine-sand background and has a clearly defined unit cell. The depth-averaged (2D) spatial distribution of the water content in the columns was monitored during the whole multi-step outflow experiment using neutron radiography. The 3D water content was measured at the steady states by neutron tomography. The experimental results are compared with the model predictions of an upscaled model derived with the homogenization theory. The parameters for the upscaled model are calculated from the hydraulic parameters of the two sand types. These hydraulic parameters were first identified in independent measurements on samples of the two individual sand types, separately. Additionally, the hydraulic parameters of both sands were identified by fitting a numerical model to the measured outflow curves. The different column structures showed a significant effect on water retention and the effective retention function, as water was trapped in the coarse-sand inclusions of the periodic structure. We included this trapping effect in the effective retention function of the upscaled model with an apparent air entry pressure. Contrary to the retention, the different packing structures had no large effect on the dynamic behavior of the outflow. The effective conductivity of the columns is therefore not significantly influenced by the structure. The upscaled models predicted the movement of the averaged water content in the two columns well. This confirms the applicability of upscaled models even if the underlying requirements are not strictly met.

Vasin, M.; Lehmann, P.; Kaestner, A.; Hassanein, R.; Nowak, W.; Helmig, R.; Neuweiler, I.

2008-09-01

134

Separability studies of construction and demolition waste recycled sand.  

PubMed

The quality of recycled aggregates from construction and demolition waste (CDW) is strictly related to the content of porous and low strength phases, and specifically to the patches of cement that remain attached to the surface of natural aggregates. This phase increases water absorption and compromises the consistency and strength of concrete made from recycled aggregates. Mineral processing has been applied to CDW recycling to remove the patches of adhered cement paste on coarse recycled aggregates. The recycled fine fraction is usually disregarded due to its high content of porous phases despite representing around 50% of the total waste. This paper focus on laboratory mineral separability studies for removing particles with a high content of cement paste from natural fine aggregate particles (quartz/feldspars). The procedure achieved processing of CDW by tertiary impact crushing to produce sand, followed by sieving and density and magnetic separability studies. The attained results confirmed that both methods were effective in reducing cement paste content and producing significant mass recovery (80% for density concentration and 60% for magnetic separation). The production of recycled sand contributes to the sustainability of the construction environment by reducing both the consumption of raw materials and disposal of CDW, particularly in large Brazilian centers with a low quantity of sand and increasing costs of this material due to long transportation distances. PMID:22835506

Ulsen, Carina; Kahn, Henrique; Hawlitschek, Gustav; Masini, Eldon A; Angulo, Sérgio C

2013-03-01

135

Sedimentology and stratigraphy of tidal sand ridges southwest Florida inner shelf  

SciTech Connect

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

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

1993-01-01

136

Batch experiments characterizing the reduction of Cr(VI) using suboxic material from a mildly reducing sand and gravel aquifer  

USGS Publications Warehouse

Batch experiments were conducted with sand collected from a shallow sand and gravel aquifer to identify the principal chemical reactions influencing the reduction of Cr(VI), so that field-observed Cr(VI) reduction could be described. The reduction appeared to be heterogeneous and occurred primarily on Fe(II)-bearing minerals. At only 1 wt %, the fine fraction (<64 ??m diameter) of the sediments dominated the amount of aqueous Cr(VI) reduction because of its greater reactivity and surface area. Although reduction of Cr(VI) increased with decreasing pH, small variations in the abundance of fine fraction among the replicate samples obscured pH trends in the batch experiments. Consistent results could only be obtained by separating the fine material from the sand and running parallel experiments on each fraction. As pH decreased (6.4 to 4.5), Cr(VI) reduction increased from 30 to 50 nmol/m2 for the sand fraction (64-1000 ??m) and from 130 to 200 nmol/m2 for the fine fraction. The amount of Cr(VI) reduced in both the sand-sized and fine material increased from 35 to 80 and from 130 to 1000 nmol/m2, respectively, for a 10-fold increase in Cr(VI)initial. A consistent description of the rate data was achieved by assuming that intraparticle diffusion limited the observed rate of reduction.

Anderson, L.D.; Kent, D.B.; Davis, J.A.

1994-01-01

137

Experimental investigation of deformation mechanisms during shear-enhanced compaction in poorly lithified sandstone and sand  

NASA Astrophysics Data System (ADS)

Shear-enhanced compaction in shallow sandstone reservoirs has been investigated in laboratory experiments using high-pressure triaxial testing of poorly lithified sandstone and sand. We have studied the deformation mechanism involved during shear-enhanced compaction and controlling parameters for yield stress at varying confining pressures for sandstone/sand with different grain sizes, porosities, and packing. Experimental testing provides insights into the deformation mechanism during hydrostatic and axial compression of coarse- and fine-grained sands with different packing including (1) natural coarse-grained sandstone, (2) densely packed fine-grained sand, and (3) loosely packed fine-grained sand. Monitoring of deformation and ultrasonic velocity during deformation indicates porosity loss, compaction, and strain hardening for most of the samples. Visualization of deformation using pretest and posttest X-ray imaging and thin sections demonstrates localized deformation fabrics and grain damage. The results show grain rearrangement as the controlling deformation mechanism for material at low stress and high porosity, whereas for lower porosity and higher stress, grain fracturing controlled the deformation. The most pronounced localization of deformation was observed for the coarse-grained, low-porosity material. A Cam-Clay cap model was used to describe the porosity loss during compaction and shear-enhanced compaction, demonstrating large inelastic compaction with increasing confining pressure. Yield stress and end caps for poorly lithified sandstone are observed for various porosities and stress conditions and found to be lower than predicted using empirical relationships for sandstone.

Skurtveit, Elin; Torabi, Anita; Gabrielsen, Roy H.; Zoback, Mark D.

2013-08-01

138

Animating Sand as a Fluid Yongning Zhu  

E-print Network

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

Bridson, Robert

139

Continuum saltation model for sand dunes  

Microsoft Academic Search

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

Gerd Sauermann; Klaus Kroy; Hans J. Herrmann

2001-01-01

140

On the critical salt concentrations for particle detachment in homogeneous sand and heterogeneous Hanford sediments  

E-print Network

On the critical salt concentrations for particle detachment in homogeneous sand and heterogeneous June 2004 Abstract One of the mechanisms for sudden particle release is a decrease in groundwater salt concentration to below the critical salt concentration (CSC), where repulsion forces between fine particles

Selker, John

141

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

E-print Network

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

Zreda, Marek

142

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

PubMed

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

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

2005-05-01

143

Aeolian processes and sand encroachment problems in Kuwait  

NASA Astrophysics Data System (ADS)

The surface of Kuwait is carved in a calcretized clastic sequence of Miocene-Pleistocene age, mostly covered by a thin blanket of recent aeolian deposits. Fast rate of development and increase of human activities contributed to denudation of the vegetative cover and exposure of dry, loose sediments to wind action. At present, Kuwait is intensively subjected to aeolian actions manifested by frequent occurrences of sand and dust storms. This dictated the need for regional understanding of the magnitude of the aeolian processes, their behavior with man-made establishments, and their long- and short-term impacts. A comparison between the nature and distribution of recent surface sediments in Kuwait in 1979 and 1990 shows significant changes that reflect the work of aeolian processes during this period. The direct impact of the enhancement of aeolian action is represented by the increase in the rate of sediment transport. Transportation of fine-grained particles in suspension frequently occurs during dust storms usually initiated in southern Iraq. The particles migrate over Kuwait as thick dust clouds and finally settle in the northern part of the Arabian Gulf. Bedload transport of sand, or saltation, frequently occurs during summer whenever wind speed reaches 5.4 m/s. The average annual sand drift rate in Kuwait is about 20 m 3 (m width) -1 yr -1, the majority of the drift occurring during the period May-August, to the southeast. Bedform transport or sand dune movement is also recognized in Kuwait. Sand dunes mostly occur as small barchans of about 3 m height. The measured rate of movement of these barchans varies with height. A barchan of average height usually moves about 20 m in nine monthes (January-August). The remarkable high rate of sand transport and the increase in development activities in the desert areas, are responsible for the enhancement of the sand encroachment problems in Kuwait. Almost all installations, roads, and farms are significantly affected by the accumulation of considerable amounts of aeolian sand. These problems have pronounced adverse environmental and economic impacts.

Khalaf, F. I.; Al-Ajmi, D.

1993-01-01

144

Drainage Experiments in Heterogeneous Sand Columns With Different Geometric Structures  

NASA Astrophysics Data System (ADS)

This poster presents results of multi-step drainage experiments, carried out with two sand columns (10x10x20 cm3) packed with different structures made up from two different sand types. One purpose was to test the influence of the column structure on the movement of the water during drainage. The second purpose was to test upscaled models for the prediction of outflow curves, even when the underlying assumptions on soil structure are not met. The two packing structures used in the experiments can be considered as two opposing extremes. The packing of the columns was made of 1x1x1 cm3 cubes of the two sand types. The first column was packed with a periodic pattern of coarse material inclusions in a fine-material background, having a clearly defined macroscopic representative elementary volume. The second column was packed with a random arrangement of the sand types that has no typical length scale smaller than that one of the column and where fine and coarse materials formed column spanning connected clusters. The depth averaged two-dimensional spatial distribution of the water content in the columns was monitored during the drainage using neutron radiography. A three dimensional tomogram of the water content was measured at steady state after each pressure step. When comparing the results from the two columns, we found that due to trapping effects the different distributions of isolated structures had an effect on the retention of drainage, indicating a significant influence of structure at effective retention curve. In contrast to the retention curve, the effective conductivity of the columns was not significantly influenced by the structure. We compared the experimental results to an upscaled model derived from homogenization theory (for slow flow processes and capillary dominated flow). It has the same form as the Richards equation with an effective retention function and an effective unsaturated hydraulic conductivity function. The hydraulic parameters of the coarse and the fine sand have been defined by least square fitting of to the measured retention curves and by fitting to the outflow curves using a Levenberg Marquardt algorithm. The hydraulic parameters were used as input to the upscaling procedure. We included the effect of structure on retention by using adapted upscaled retention curves, which consider the accessability of inclusion material to air during drainage. The upscaled models predicted the movement of the averaged water content in the two columns well. This can be considered to confirm the applicability of upscaled models even if the underlying requirements are not strictly met.

Vasin, M.; Lehmann, P.; Nowak, W.; Hassanein, R.; Neuweiler, I.

2007-12-01

145

EFFECTS OF STORAGE ON THE TOXICITY OF SEDIMENTS SPIKED WITH FLUORANTHENE TO THE AMPHIPOD, RHEPOXYNIUS ABRONIUS  

EPA Science Inventory

To determine the effect of storage on contaminant bioavailability and toxicity, two sediment types, a fine sand and silty sand, were spiked with nine concentrations of fluoranthene (0.0-50 mg/dry kg) then stored at 4?C for up to 170d. Toxicity of the stored sediment was dete...

146

Excess pore pressure and grain crushing of sands by means of undrained and naturally drained ring-shear tests  

Microsoft Academic Search

An investigation of excess pore-pressure generation of a weathered granitic sand, taken from the source area of a typical landslide caused as a result of liquefaction, and a fine silica sand was conducted, in which grain crushing within the shear zone of ring-shear test specimens was examined as the key phenomenon of rapid long-runout motion of landslides. In order to

Yasuhiko Okada; Kyoji Sassa; Hiroshi Fukuoka

2004-01-01

147

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

USGS Publications Warehouse

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

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

2000-01-01

148

Dewatering of fine coal  

SciTech Connect

The factors which control the dewatering of fine coal by gravity/centrifugal drainage and by gas displacement (vacuum/hyperbaric filtration) are evaluated. A generalized model is presented and used to describe dewatering kinetics and to establish dewatering limits. Applications to the design of dewatering systems for fine coal dewatering are discussed.

Hogg, R. [Mineral Processing Section, University Park, PA (United States)

1995-10-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

150

Horizontal ethanol floods in clean, uniform, and layered sand packs under confined conditions  

NASA Astrophysics Data System (ADS)

Six ethanol floods were conducted in clean, uniform, and layered crystal silica sands to establish a baseline performance and sweep efficiency of ethanol flooding in clean sand packs under confined conditions. Flow experiments were conducted with horizontal darcy velocities of the order of 4 to 12 m d-1. At darcy velocities less than 5 m d-1 the time required for the propagating ethanol front to reach its stable configuration compared well with predictions based on a model of gravity segregation of miscible liquids in a no-flow domain. The stabilized angles of the advancing ethanol front in uniform fine sand packs varied between 45° and 77°, depending on the darcy velocity. Poor agreement was obtained between the measured inclination angles and predictions based on several previously published sharp interface models that exclude the effects of dispersion. However, the measured inclination angles compare well with the angles predicted by the method of Hawthorne [1960] when the method is modified to account for the peak viscosity of the ethanol-water system. Finally, in layered sand packs using coarse and fine sands, gravity override of the ethanol was greatly exaggerated because of anisotropy introduced by the layering.

Grubb, Dennis G.; Sitar, Nicholas

1999-11-01

151

Intramural Sports Sand Volleyball League  

E-print Network

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

Escher, Christine

152

Influence of a dam on fine-sediment storage in a canyon river  

Microsoft Academic Search

Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination

Joseph E. Hazel Jr; David J. Topping; John C. Schmidt; Matt Kaplinski

2006-01-01

153

Influence of fly ash fineness and shape on the porosity and permeability of blended cement pastes  

Microsoft Academic Search

The effects of the fineness and shape of fly ash on the porosity and air permeability of cement pastes were investigated.\\u000a Pulverized coal combustion (PCC) fly ash and fluidized bed coal combustion (FBC) fly ash classified into three different finenesses\\u000a were used. River sand with particle size distribution similar to that of fly ash was also used for comparison. Portland

Theerawat Sinsiri; Prinya Chindaprasirt; Chai Jaturapitakkul

2010-01-01

154

Soil parameters required to simulate the dynamic lateral response of model piles in sand  

E-print Network

. - The model piles were tested in a borrow area along State Highway 30 approximately 4. 8 miles east of the intersection of State Highway 30 and Farm to Market road 158 in Brazos County. The soil at this site can visually be classified as a gray, fine sand... of &' for the sand at the test site. 23 COMPARISON OF FIELD AND PREDICTED PILE RESPONSE General. - The computer program developed by Ross (15) for the dynamic response of a laterally loaded offshore pile was used to predict model pile response in this 1...

Wright, David Allen

2012-06-07

155

Development of stresses in cohesionless poured sand  

E-print Network

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

Claudin, Philippe

156

EFFECTS of OIL MIXED with CARBONIZED SAND  

E-print Network

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

157

Animating Sand as a Fluid Yongning Zhu  

E-print Network

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

Teschner, Matthias

158

Fluvial sand shapes: effects of tributary mixing  

Microsoft Academic Search

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

1985-01-01

159

Treating tar sands formations with karsted zones  

DOEpatents

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

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

2010-03-09

160

Sand Dome on a Steam Engine  

USGS Multimedia Gallery

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

161

Permeability predictions for sand-clogged Portland cement pervious concrete pavement systems.  

PubMed

Pervious concrete is an alternative paving surface that can be used to reduce the nonpoint source pollution effects of stormwater runoff from paved surfaces such as roadways and parking lots by allowing some of the rainfall to permeate into the ground below. This infiltration rate may be adversely affected by clogging of the system, particularly clogging or covering by sand in coastal areas. A theoretical relation was developed between the effective permeability of a sand-clogged pervious concrete block, the permeability of sand, and the porosity of the unclogged block. Permeabilities were then measured for Portland cement pervious concrete systems fully covered with extra fine sand in a flume using simulated rainfalls. The experimental results correlated well with the theoretical calculated permeability of the pervious concrete system for pervious concrete systems fully covered on the surface with sand. Two different slopes (2% and 10%) were used. Rainfall rates were simulated for the combination of direct rainfall (passive runoff) and for additional stormwater runoff from adjacent areas (active runoff). A typical pervious concrete block will allow water to pass through at flow rates greater than 0.2 cm/s and a typical extra fine sand will have a permeability of approximately 0.02 cm/s. The limit of the system with complete sand coverage resulted in an effective system permeability of approximately 0.004 cm/s which is similar to the rainfall intensity of a 30 min duration, 100-year frequency event in the southeastern United States. The results obtained are important in designing and evaluating pervious concrete as a paving surface within watershed management systems for controlling the quantity of runoff. PMID:16563606

Haselbach, Liv M; Valavala, Srinivas; Montes, Felipe

2006-10-01

162

Anatomy of a shoreface sand ridge revisted using foraminifera: False Cape Shoals, Virginia/North Carolina inner shelf  

USGS Publications Warehouse

Certain details regarding the origin and evolution of shelf sand ridges remain elusive. Knowledge of their internal stratigraphy and microfossil distribution is necessary to define the origin and to determine the processes that modify sand ridges. Fourteen vibracores from False Cape Shoal A, a well-developed shoreface-attached sand ridge on the Virginia/North Carolina inner continental shelf, were examined to document the internal stratigraphy and benthic foraminiferal assemblages, as well as to reconstruct the depositional environments recorded in down-core sediments. Seven sedimentary and foraminiferal facies correspond to the following stratigraphic units: fossiliferous silt, barren sand, clay to sandy clay, laminated and bioturbated sand, poorly sorted massive sand, fine clean sand, and poorly sorted clay to gravel. The units represent a Pleistocene estuary and shoreface, a Holocene estuary, ebb tidal delta, modern shelf, modern shoreface, and swale fill, respectively. The succession of depositional environments reflects a Pleistocene sea-level highstand and subsequent regression followed by the Holocene transgression in which barrier island/spit systems formed along the Virginia/North Carolina inner shelf not, vert, ~5.2 ka and migrated landward and an ebb tidal delta that was deposited, reworked, and covered by shelf sand.

Robinson, Marci M.; McBride, Randolph A.

2008-01-01

163

Anatomy of a shoreface sand ridge revisited using foraminifera: False Cape Shoals, Virginia/North Carolina inner shelf  

USGS Publications Warehouse

Certain details regarding the origin and evolution of shelf sand ridges remain elusive. Knowledge of their internal stratigraphy and microfossil distribution is necessary to define the origin and to determine the processes that modify sand ridges. Fourteen vibracores from False Cape Shoal A, a well-developed shoreface-attached sand ridge on the Virginia/North Carolina inner continental shelf, were examined to document the internal stratigraphy and benthic foraminiferal assemblages, as well as to reconstruct the depositional environments recorded in down-core sediments. Seven sedimentary and foraminiferal facies correspond to the following stratigraphic units: fossiliferous silt, barren sand, clay to sandy clay, laminated and bioturbated sand, poorly sorted massive sand, fine clean sand, and poorly sorted clay to gravel. The units represent a Pleistocene estuary and shoreface, a Holocene estuary, ebb tidal delta, modern shelf, modern shoreface, and swale fill, respectively. The succession of depositional environments reflects a Pleistocene sea-level highstand and subsequent regression followed by the Holocene transgression in which barrier island/spit systems formed along the Virginia/North Carolina inner shelf ???5.2 ka and migrated landward and an ebb tidal delta that was deposited, reworked, and covered by shelf sand.

Robinson, M.M.; McBride, R.A.

2008-01-01

164

Thermal Properties of oil sand  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

165

Tracing biogeochemical and microbial variability over a complete oil sand mining and recultivation process.  

PubMed

Recultivation of disturbed oil sand mining areas is an issue of increasing importance. Nevertheless only little is known about the fate of organic matter, cell abundances and microbial community structures during oil sand processing, tailings management and initial soil development on reclamation sites. Thus the focus of this work is on biogeochemical changes of mined oil sands through the entire process chain until its use as substratum for newly developing soils on reclamation sites. Therefore, oil sand, mature fine tailings (MFTs) from tailings ponds and drying cells and tailings sand covered with peat-mineral mix (PMM) as part of land reclamation were analyzed. The sample set was selected to address the question whether changes in the above-mentioned biogeochemical parameters can be related to oil sand processing or biological processes and how these changes influence microbial activities and soil development. GC-MS analyses of oil-derived biomarkers reveal that these compounds remain unaffected by oil sand processing and biological activity. In contrast, changes in polycyclic aromatic hydrocarbon (PAH) abundance and pattern can be observed along the process chain. Especially naphthalenes, phenanthrenes and chrysenes are altered or absent on reclamation sites. Furthermore, root-bearing horizons on reclamation sites exhibit cell abundances at least ten times higher (10(8) to 10(9) cells g(-1)) than in oil sand and MFT samples (10(7) cells g(-1)) and show a higher diversity in their microbial community structure. Nitrate in the pore water and roots derived from the PMM seem to be the most important stimulants for microbial growth. The combined data show that the observed compositional changes are mostly related to biological activity and the addition of exogenous organic components (PMM), whereas oil extraction, tailings dewatering and compaction do not have significant influences on the evaluated compounds. Microbial community composition remains relatively stable through the entire process chain. PMID:25201817

Noah, Mareike; Lappé, Michael; Schneider, Beate; Vieth-Hillebrand, Andrea; Wilkes, Heinz; Kallmeyer, Jens

2014-11-15

166

Sand Sheet on Crater Floor  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

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

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

Image information: VIS instrument. Latitude 26.4, Longitude 62.7 East (297.3 West). 19 meter/pixel resolution.

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

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

2005-01-01

167

The Chemistry of Saudi Arabian Sand - A Deposition Problem on Helicopter Turbine Airfoils  

NASA Technical Reports Server (NTRS)

Operations in the Persian Gulf have exposed military helicopter turbines to excessive amounts of ingested sand. Fine particles, less than 10 microns, are able to bypass the particle separators and enter the cooling and combustion systems. The initial sand chemistry varies by location, but is made up of a calcium aluminum silicate glass, SiO2 low quartz, (Ca,Mg)CO3 dolomite, CaCO3 calcite, and occasionally NaCl rocksalt. The sand reacts in the hot combustion gases and deposits onto the turbine vanes as CaSO4, glass, and various crystalline silicates. Deposits up to 5 mm thick have been collected. Although cooling hole plugging is a considerable problem, excessive corrosion is not commonly observed due to the high melting point of CaSO4.

Smialek, James L.; Archer, Frances A.; Garlick, Ralph G.

1992-01-01

168

FINE PARTICLE CHARGING DEVELOPMENT  

EPA Science Inventory

The report gives results of theoretical and experimental investigations into the changing of fine particles by unipolar ions in an electric field, and evaluation of a specially designed small pilot-scale (600-1000 acfm) precharging device. Following an extensive review of the lit...

169

Morris. E. Fine symposium  

Microsoft Academic Search

Professor Morris E. Fine is a pioneer in teaching the unifying concepts underlying all classes of materials: metals, ceramics, polymers, and electronic materials. He is a founder and the guiding genius of the first materials science department in the world. His research career at Northwestern University has spanned a broad range of topics, from physical chemistry to mechanical behavior, and

P. K. Liaw; H. L. Marcus; J. R. Weertman; J. S. Santer

1990-01-01

170

MAIZE FINE STREAK VIRUS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The report outlines the salient features of maize fine streak virus (MFSV) including a general description of the causal virus species, virion properties, genome description, the relationship of the virus to other taxa, biological properties of the disease and agronomic aspects of the disease. Maize...

171

Dewatering of fine coal  

SciTech Connect

Fine coal dewatering is one of the most pressing problem facing the coal cleaning industry. This project was undertaken with the objective of improving the dewatering process with surface chemical activation by primarily understanding the fundamental and process engineering aspects of vacuum filtration. Specific tasks for this project included -- development of an experimental apparatus and procedure to yield highly reproducible results and extensive data from each test, detailed experimental investigation of the dewatering characteristics of coal fines with and without the addition of flocculants and surfactants, and under different operating conditions, and finally identification and establishment of the physical limits of mechanical dewatering. Following are the significant conclusions from the study: Fineness and size distribution of the coal fines have the most significant influence on the coal dewatering process; usage of flocculants and surfactants is almost essential in reducing the cake moisture and in increasing the filter throughputs; based on the experimental data and the literature information, the existence of an asymptotic limit for filter cake moisture correlatable with a capillary number of the filter cake was identified. 66 refs., 23 figs., 7 tabs.

Sastry, K.V.S. (California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering)

1991-01-01

172

Two Kinds of Gas Hydrate Reservoirs: Pore-filling Sand vs. Fractured Clay  

Microsoft Academic Search

Recent marine gas hydrate expeditions, such as the Indian National Gas Hydrate Program Expedition 01 (NGHP-01) on the Indian continental margin and the Chevron\\/Department of Energy Joint Industry Project Legs 1 & 2 (JIP1 and JIP2) in the Gulf of Mexico, revealed both fine-grained sediments containing near-vertical gas hydrate filled fractures and sand reservoirs which are likely containing pore filling

A. Cook; D. Goldberg

2009-01-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

174

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

Microsoft Academic Search

Sand transport in the Colorado River in Marble and Grand Canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in suspended-sand concentration, (2) hysteresis in suspended-sand grain size coupled to the hysteresis in suspended-sand concentration, (3) production

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

2007-01-01

175

Late Quaternary evolution of the sub-aqueous Yangtze Delta, China: sedimentation, stratigraphy, palynology, and deformation  

Microsoft Academic Search

Four sediment belts (A–D) of the Yangtze sub-aqueous delta are defined from the sea-bottom sediment distribution. Belt A, delta front fine sand and silt, with trough cross stratification; Belt B, prodelta silty clay and clayey silt, with abundant burrowing and rich in organic matter; Belt C, prodelta to continental shelf sand–silt–clay, with thin layers of sand and clay interbedded; and

Zhongyuan Chen; Baoping Song; Zhanghua Wang; Yongli Cai

2000-01-01

176

Downstream Grain-Size Variation to Interpret River-Channel Process-form in the Middle-Lower Yangtze River, China  

Microsoft Academic Search

\\u000a In 2000 and 2003, five-hundred and twenty (520) riverbed sediment samples were taken from the middle-lower Yangtze trunk channel\\u000a to examine the river hydromorphological nature. Analytical result shows that the riverbeds mostly consist of mostly medium\\u000a to coarse sands, but silty fine sand near the river coast. The result further indicates 12 zones (I–XII), identified as alternated\\u000a coarse- fine-grained riverbed,

Zhanjiao Wang; Zhongyuan Chen

177

A branching process model for sand avalanches  

SciTech Connect

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

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

1993-07-01

178

Cell abundance and microbial community composition along a complete oil sand mining and reclamation process  

NASA Astrophysics Data System (ADS)

Hydrocarbons constitute an important energy source for microbes but can also be of environmental concern. Microbial activity causes hydrocarbon degradation and thereby loss of economical value, but also helps to remove hydrocarbons from the environment. The present study characterizes the abundance of microbes along the oil sand mining process in Alberta, Canada, as a first approach to assess the impact of mining and oil extraction on the microbial population. After mining the oil is extracted from the sediment by a hot-water extraction (50-60°C), resulting in three major fractions: crude oil, tailings sand and fine tailings. The tailings sand is used as substratum for newly developing soils on the reclamation areas. The very liquid fine tailings still have a TOC content of about 4.3% and are pumped into tailings ponds, where they need up to three decades to settle and solidify. After deposition, these mature fine tailings (MFTs) are enriched in organics (TOC content between 9.6 and 16.8%) and dredged out of the ponds and put on dumps for several years for dewatering. Finally they are brought out onto the reclamation sites and deposited below the sand layer. Cells were extracted from oily sediments according to the protocol of Lappé and Kallmeyer (2011), stained with SYBR Green I and counted by fluorescence microscopy. Cell abundance in the unprocessed oil sand is around 1.6 x 107 cells cm-3. After processing the fresh fine tailings still contain around 1.6 x 107 cells cm-3. Cell counts in the processed MFTs are 5.8 x 107 cells cm-3, whereas in the sand used as substratum for newly developing soils, they are twice as high (1.4 x 108). In root-bearing horizons, cell counts reach 1.1 x 109 cell cm-3. Cell numbers calculated from cultivation experiments are in the same range. Higher cell counts in the tailings sand are probably due to a higher nitrogen supply through the addition of a 35 cm top layer of a peat-mineral mix. In the sand nitrate concentrations are high (~0.37 mmol/L), whereas in the MFTs nitrate concentrations are much lower (~0.04 mmol/L). In some MFT samples sulphate appears to be the most abundant electron acceptor (up to 94 mmol/L) but no hydrogen sulphide could be detected. High cell counts in root-bearing layers might be related to a supply with otherwise unavailable nutrients, especially phosphorus. Another plausible explanation is that the cells are brought in the sand with the peat-mineral mix, because it seems that the mix contains a significant amount of roots. Samples with low amounts or no roots showed lower cell abundances. Sand and MFTs also differ in the microbial community composition. Molecular analysis of bacterial isolates of samples with different oil content show that ?-Proteobacteria dominate the cultivable bacterial population in substrates with a high residual content of oil, whereas in the low oil content sand they play a minor role. The data of corresponding metagenomic analyses confirm these results. In MFTs ?-Proteobacteria make up about 80% of the total bacterial population. The surprisingly stable cell abundance indicates that microbial processes take place throughout the entire production process. Rising cell numbers in root-bearing horizons show that a plant cover fosters microbial abundance and diversity, helping to restore full ecosystem functionality.

Lappé, M.; Schneider, B.; Kallmeyer, J.

2012-12-01

179

Trends in Gypsiferous Aerosol Downwind of White Sands, New Mexico  

NASA Astrophysics Data System (ADS)

White Sands is a known 'hotspot' of dust emissions in southwestern North America where an active gypsum dunefield abuts erodible playa sediments. Aerosols entrained from White Sands are sometimes visible on satellite images as distinct, light-colored plumes crossing the Sacramento Mountains to the northeast. The U.S. Forest Service operates an aerosol sampler at White Mountain in the lee of the Sacramento range as part of the IMPROVE network (Interagency Monitoring of PROtected Visual Environments). In recent years a spring pulse of sulfate aerosol has appeared at White Mountain, eclipsing the regional summer peak attributed to atmospheric reactions of sulfur dioxide emissions. A significant fraction of this spring sulfate is contributed by gypsum and other salts from White Sands, with clearly increased concentrations of calcium, strontium, and chloride. The increase in these species coincides with a drought following a period of above-average precipitation. White Sands and White Mountain thus provide an unusually well-defined natural laboratory: a climatically sensitive dust source that is both well characterized and chemically distinct from its surroundings, with a signature that remains identifiably distinct at a long-term observatory ~100 km downwind. This paper examines the routine PM2.5 (fine-particle, Dp < 2.5 um) composition data available from White Mountain and other regional IMPROVE sites (e.g. Bosque del Apache), supplemented by some elemental analysis of collocated PM10 samples. The ambient data are compared with chemical analyses of surface samples from White Sands, bulk dry dustfall and soil surface composition at White Mountain, satellite observations of dust plumes, and available meteorological records. Together, the observations document significant, episodic aeolian transport of gypsum and other salts across the Sacramento Mountains. Figure 1. Left: Monthly average concentrations of every-third-day 24h samples. Top right: MODIS image, 2/28/2012, http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=77294). Bottom right: Correlation (r) matrix for 2011 daily elemental data from White Mountain (n = 105).

White, W. H.; Trzepla, K.; Yatkin, S.; Gill, T. E.; Jin, L.

2013-12-01

180

Fine Arts in Hungary  

NSDL National Science Digital Library

This Website, sponsored by KFKI Computers of Budapest, presents a virtual gallery of images of fine arts from Hungary (.jpeg, you choose view size.) This Central European nation, at times under the influence of the Romans, Turks and Austro-Hungarian Empire, houses a rich artistic tradition. Works of Hungarian fine artists as well as others that worked in Hungary are featured here in alphabetical order by artist. There's also a section of altarpieces, miniatures, carvings, etc. by anonymous artists. Visitors to the site will enjoy the collection, which includes fragments of Romanesque wall paintings and architectural sculpture, Gothic and Renaissance altarpieces and carvings, paintings from the baroque, classicist and romanticist periods, and modern art. The short biographies of the artists will aid in appreciation of the talented yet not all internationally-known artists of Hungary. You might even want to send a virtual postcard from the site.

Krãâ©n, Emil.; Marx, Dãâ¡niel.

1997-01-01

181

Water transfer between rock fragments and fine earth in remoulded soils  

NASA Astrophysics Data System (ADS)

Stony soils cover about 30% of the surface soils of Western Europe, and 60% in Mediterranean areas. Rock fragments may alter the physical, chemical and agricultural properties of soils. They are also a potential reservoir of water and nutrients for plants, suggesting that the stony phase of soil can participate in water supply to crops and affect the storage capacity of soil water. This implies the existence of water transfer between rock fragments and fine earth. To better understand the interaction between the fine earth and rock fragments, we studied the water transfer between pebbles and fine earth on remoulded soils in presence and absence of plants. Experiments were conducted on remoulded soils in containers (3 L), under controlled conditions. Pebbles and fine earth were collected separately from the Ap horizon of a calcareous lacustrine limestone silty soil located in the central region of France. Pebbles were mixed with fine earth to reach a bulk density of the fine earth of 1.1 g/cm3. Four modalities with different percentage in volume of pebbles were created: 0%p: 0 % pebbles + 100 % fine earth + plant 20%p: 20 % pebbles + 80% fine earth + plant 40%p: 40 % pebbles + 60% fine earth + plant 40%: 40 % pebbles + 60% fine earth Fifteen containers were created for each modality and cuttings of Populus robusta were planted in the three first modalities. All containers were saturated, then irrigated by capillarity and controlled to maintain a moderate water stress continuously. After three months, the containers were saturated again and then allowed to dry. At that time, plants were from 27 to 43 cm height depending on the modality. Soil samples were collected at 5 dates following this second saturation: D0 = soil water content equal to the Available Water Content, Day 2 = D0 + 2 days, Day 4 = D0 + 4 days, Day 7 = D0 + 7 days, Day 11= D0 + 11 days. At each sampling date, three containers for each modality were used to measure the gravimetric water content separately for fine earth and pebbles, and at five depths. Differences in water content between pebbles and fine earth, and between dates, were analysed by a variance analysis (ANOVA, threshold at 5%). Results showed different behaviours for water loss between fine earth and pebbles during a drying period of 11 days. While water content of fine earth decreased from the beginning and onward, pebbles only started to lose water several days after. To study the effect of pebbles proportion, modalities "0%p", "20%p" and "40%p" were compared. Fine earth of modality without pebbles (0%p) lost water faster compared to modalities with pebbles ("20%p" and "40%p") from the 7th day. Meanwhile, pebbles lose water only from the 4th or 7th day. In addition, comparisons of containers at 40% with and without plants ("40%p" and "40%") showed that the water content decreased at a similar rate for the fine earth while the drying of the rock fragments was more pronounced with a plant at the end of the drying period. The moisture of fine earth reduced on average 1.3 times faster with a plant than without. So, plants enhanced the drying processes due to their transpiration but did not seem to modify the water transfer trends. This study showed a water transfer from pebbles towards fine earth occurs, especially when drought starts to be severe, which could be benefit to plant.

Tetegan, Marion; Korboulewsky, Nathalie; Bouthier, Alain; Cousin, Isabelle

2010-05-01

182

Water Use for Cultivation Management of Watermelon in Upland Field on Sand Dune  

NASA Astrophysics Data System (ADS)

Early-maturing cultivation of watermelon in a plastic tunnel was invetigated in upland field on sand dune on the coast of the Japan Sea to find water use to control blowing sand and to transplant seedlings. This region has low precipitation, low humidity, and strong wind in March and April, when sand is readily blown in the field. Water is used to control blowing sand on days with precipitation below 5 mm, minimum humidity below the meteorological average in April, and maximum wind velocity above the meteorological average in April. For the rooting and growth of watermelon seedlings, soil temperature needs to be raised because it is low in April. Ridges are mulched with transparent, porous polyethylene films 10 or more days before transplanting the seedlings and irrigated with sprinklers on fine days for the thermal storage of solar energy. The stored heat steams the mulched ridges to raise soil temperature to 15°C or higher on the day of transplanting the seedlings. The total amount of irrigation water used for watermelon cultivation was 432.7 mm, of which 23.6 mm was for blowing sand control and 26.6 mm was for transplanting the seedlings. The combined amount, 50.2 mm, is 11.6% of the total amount of water used for cultivation management.

Hashimoto, Iwao; Senge, Masateru; Itou, Kengo; Maruyama, Toshisuke

183

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

SciTech Connect

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

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

1991-02-01

184

Alteration of the Hydraulic and Seismic Properties of a Fracture by Mineral Precipitation and Sand Deposition  

NASA Astrophysics Data System (ADS)

In the near subsurface, rocks are exposed to multiple natural and human made processes that can alter the properties of the rock. These processes can be chemical dissolution, mineral precipitation as well as sand deposition and transport. All these processes alter the hydrological and seismic properties of fractured rock. In this study we used a fractured carbonate rock (150 mm of diameter and 75 mm of height) to study the effect of mineral precipitation and fine sand deposition on the hydrological and seismic properties of the fracture. Prior to geochemical and transport alteration of the fracture, surface roughness measurements were made using laser profilometry to quantify the fracture void geometry. Reconstruction of the fracture void geometry showed quasi-linear channels through the fracture with a correlation length of 20 mm. The long linear channels were not observed in the seismic data for the fracture when it was initially saturated with water. For seismic measurements, water usually masks heterogeneity in a fracture. However, the flow measurements made from eight ports around the sample did indicate flow anisotropy. Next, the fracture void geometry was altered using a solution of hydrochloric acid and sulfuric acid to alternately etch the fracture and precipitate gypsum in the fracture. This reactive solution resulted in an increase in flow rate for several ports but not all. The seismic data showed that portions of the fracture exhibited enhanced transmission, while other portions exhibited a decrease in transmission. Finally, fine sand transport and deposition were performed by using an aqueous containing solid spherical silica beads (an average radius of 25 micrometers). While the flow rate remained relatively constant in three out of four ports, the seismic transmission across the fracture increased. In addition, the structure of the void geometry became apparent in the seismic data. We hypothesize that the deposition of the fine sand was controlled by the fracture flow path geometry and preferentially deposited along regions of contacts or small apertures. In this experiment, the aqueous sand solution had a concentration of 0.23 g per 100 ml. For this concentration, the fine sand provided additional coupling between the fracture surfaces thereby enhancing seismic wave propagation but did not significantly affecting the flow properties of the fracture. Acknowledgments: LJPN wishes to acknowledge the Geosciences Research Program, Office of Basic Energy Sciences US Department of Energy DE-FG02-97ER14785 08 for support of this research.

Acosta-Colon, A. A.; Pyrak-Nolte, L. J.

2006-12-01

185

A high-efficiency, low-cost aeolian sand trap  

NASA Astrophysics Data System (ADS)

We present a design for an aeolian sand trap that is based on the streamer trap concept used in sediment transport studies. The trap is inexpensive, has excellent trapping efficiency, is durable, and easy to use. It is fabricated from stainless steel that is cut and bent to form a frame to support a fine nylon mesh. Typical trap openings are 100 mm wide and 25, 50, or 100 mm high. Traps are 250 mm long, and are stackable to measure vertical characteristics of saltation. The nylon mesh has 64 ?m openings that comprise 47% of the area of the material. Aerodynamic efficiency was tested in a wind tunnel, and sediment trapping efficiency evaluated in field deployments. Both evaluations support the use of this trap for short-term measurements.

Sherman, D. J.; Swann, C.; Barron, J. D.

2014-06-01

186

Reversal in Migration of Gravel-Sand Transition  

NASA Astrophysics Data System (ADS)

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

Kim, W.

2011-12-01

187

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

Microsoft Academic Search

Sand transport in the Colorado River in Marble and Grand canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in sediment concentration, (2) hysteresis in sediment grain size coupled to the hysteresis in sediment concentration, (3) production

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

2007-01-01

188

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

USGS Publications Warehouse

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

Dingler, John R.; Reiss, Thomas E.

1987-01-01

189

White Sands, Carrizozo Lava Beds, NM  

NASA Technical Reports Server (NTRS)

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

1973-01-01

190

NEW DEVELOPMENTS IN SLOW SAND FILTRATION  

EPA Science Inventory

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

191

Introduction to Exploring Sand and Water  

ERIC Educational Resources Information Center

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

Early Childhood Today, 2006

2006-01-01

192

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

E-print Network

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

Walter, M.Todd

193

Onsite Wastewater Treatment Systems: Sand Filters  

E-print Network

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

Lesikar, Bruce J.

2008-10-23

194

White Sands National Monument: Education Fact Sheets  

NSDL National Science Digital Library

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

195

Ottawa Sand for Mechanics of Granular Materials (MGM) Experiment  

NASA Technical Reports Server (NTRS)

What appear to be boulders fresh from a tumble down a mountain are really grains of Ottawa sand, a standard material used in civil engineering tests and also used in the Mechanics of Granular Materials (MGM) experiment. The craggy surface shows how sand grans have faces that can cause friction as they roll and slide against each other, or even causing 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. MGM uses 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. These images are from an Electron Spectroscopy for Chemical Analysis (ESCA) study conducted by Dr. Binayak Panda of IITRI for Marshall Space Flight Center (MSFC). (Credit: NASA/MSFC)

2000-01-01

196

UMore Park Sand and Gravel Resources Project University of Minnesota  

E-print Network

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

Netoff, Theoden

197

Influence of fly ash fineness and shape on the porosity and permeability of blended cement pastes  

NASA Astrophysics Data System (ADS)

The effects of the fineness and shape of fly ash on the porosity and air permeability of cement pastes were investigated. Pulverized coal combustion (PCC) fly ash and fluidized bed coal combustion (FBC) fly ash classified into three different finenesses were used. River sand with particle size distribution similar to that of fly ash was also used for comparison. Portland cement was replaced with fly ash and ground sand at the dosages of 0, 20wt%, and 40wt%. A water-to-binder ratio (w/b) of 0.35 was used throughout the experiment. The results show that the porosity and air permeability of the pastes are influenced by the shape, fineness, and replacement level of fly ash. The porosity and air permeability of FBC fly ash pastes are higher than those of PCC fly ash pastes. This is due to the higher irregular shape and surface of FBC fly ash compared to the spherical shape and relatively smooth surface of PCC fly ash. The porosity increases with the increase in fly ash replacement level and decreases with the increase in its fineness. The permeability of PCC fly ash pastes decreases with the increase in replacement level and fineness, while for FBC fly ash, the permeability increases with the increase in replacement level. Decreases in porosity and permeability are due to a combined effect of the packing of fine particles and the reaction of fly ash.

Sinsiri, Theerawat; Chindaprasirt, Prinya; Jaturapitakkul, Chai

2010-12-01

198

Compositional Variations of Rocknest Sand, Gale Crater, Mars  

NASA Astrophysics Data System (ADS)

The Curiosity rover spent over 40 sols at an aeolian deposit (termed Rocknest sand shadow deposit) that is several meters long (oriented north-south), 15-20 cm high (at crest) and about 50 cm wide. Material was scooped up from the subsurface to a depth of about 40 mm at five different locations on the deposit. Part of the sampled material was delivered to the analytical laboratories CheMin (x-ray diffraction) and SAM (pyrolysis, evolved gas analysis, gas chromatography, mass spectrometry, tunable laser spectroscopy) in the rover body. Scoop troughs and walls were imaged extensively by cameras onboard the rover (Mastcam, Mars Hand Lens Imager (MAHLI), Remote Microscopic Imager (RMI)) and probed by Laser Induced Breakdown Spectroscopy (LIBS) as provided by the ChemCam instrument. Images show that the top surface of the deposit is armored by a layer 1-3 grains thick of mm-sized, subrounded, dust-mantled grains. The bulk of the deposit is composed of particles smaller than 150 microns (fine and very fine sand and likely silt and dust). Furthermore, there are bright bands in the subsurface, a narrow one and a broad one at depths 2-4 mm and 20-30 mm, respectively. The images also provide evidence for crust formation and cementation as the scoop trough floors are littered by platy angular fragments and cemented clods. Many of the clods contain numerous sub-mm sized bright (sulfate rich?) inclusions. Chemical profiles (as provided by ChemCam data) do not clearly support the type of subsurface layering inferred from the images. However, chemical abundances (Li, Na, K, Mn, Fe, Ca, Mg, and Si) significantly deviating from average values are found at two different depths (respectively 15 and 25 mm). It is unclear when (and over which time scale) the Rocknest sand deposit in Gale Crater formed. In any case, mm-sized particles cannot be moved efficiently in the current aeolian regime. If the deposit has been immobile for an extended period of time, it is conceivable that Martian obliquity cycles (up to the near geologic past) caused ice deposition and partial melting of subsurface water ice which in turn may have sustained slow alteration of the uppermost part of the deposit (Arvidson et al., J. Geophys. Res., 115, E00F03, 2010); this hypothesis is consistent with the observed crust formation as well as the chemical variations in the near subsurface.

Goetz, Walter; Madsen, Morten B.; Edgett, Kenneth S.; Clark, Benton C.; Meslin, Pierre-Yves; Blaney, Diana L.; Bridges, Nathan; Fisk, Martin; Hviid, Stubbe F.; Kocurek, Gary; Lasue, Jeremie; Maurice, Sylvestre; Newsom, Horton; Renno, Nilton; Rubin, David M.; Sullivan, Robert; Wiens, Roger C.; MSL Science Team

2013-04-01

199

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

USGS Publications Warehouse

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

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

1988-01-01

200

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

PubMed Central

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

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

2011-01-01

201

Invasive plants on disturbed Korean sand dunes  

NASA Astrophysics Data System (ADS)

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

Kim, Kee Dae

2005-01-01

202

Skin friction for steel piles in sand  

E-print Network

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

Sulaiman, Ibrahim Hikmat

2012-06-07

203

Fine gravel controls hydrologic and erodibility responses to trampling disturbance for coarse-textured soils with weak cyanobacterial crusts.  

Technology Transfer Automated Retrieval System (TEKTRAN)

We compared short-term effects of lug-soled boot trampling disturbance on water infiltration and soil erodibility on coarse-textured soils covered by a mixture of fine gravel and coarse sand over weak cyanobacterially-dominated biological soil crusts. Trampling significantly reduced final infiltrati...

204

Automated Camera Array Fine Calibration  

NASA Technical Reports Server (NTRS)

Using aerial imagery, the JPL FineCalibration (JPL FineCal) software automatically tunes a set of existing CAHVOR camera models for an array of cameras. The software finds matching features in the overlap region between images from adjacent cameras, and uses these features to refine the camera models. It is not necessary to take special imagery of a known target and no surveying is required. JPL FineCal was developed for use with an aerial, persistent surveillance platform.

Clouse, Daniel; Padgett, Curtis; Ansar, Adnan; Cheng, Yang

2008-01-01

205

Geomorphic controls on fine sediment reinfiltration into salmonid spawning gravels and the implications for spawning habitat rehabilitation  

NASA Astrophysics Data System (ADS)

Anthropogenic activities often increase the flux of fine sediment to fluvial environments. In gravel-bed streams the extent to which augmented fines loading causes the degradation of vital interstitial habitats is determined by factors controlling fines infiltration into channel substratum. Previous research suggests that substrate pore constriction size, intensity of upwelling interstitial flow, and the quantity of fines transported across the bed surface (i.e., exposure dose) are three important factors controlling substrate fines content. Few field studies have investigated the interactive effects of these physical factors. We constructed 17 experimental redds in brook trout spawning microhabitats in a boreal forest stream in Quebec, Canada, to investigate the role of pore constriction size, hyporheic flow, and exposure dose on substrate fines content. To simulate the effect of spawning in coarsening the substrates, redds were partially cleaned of coarse sand and of all fine sediment (< 0.5 mm). Results show that coarse sands and fine gravel (0.5-4 mm; filter class) acted as a filter of percolating fine sediment (< 0.5 mm). We found that this filtering effect (i.e., lower fines density at egg pocket depth) occurred at sites where the proportion of the filter class in the substratum above egg pocket depth exceeded a threshold value of 18%, as indicated by a statistically significant step-function response between fines gradient with depth and the filter class content in the uppermost layers of the bed. Results also indicated that fines content at depth was unrelated to fines exposure. Estimated upward seepage rates were well below the threshold velocity that would inhibit the percolation of medium-grained sand (i.e., 0.5 mm) into the bed. These results suggest that within these gravel-bed spawning substrates the abundance of filter classes was the primary determinant of fines content at depth. This study highlights the importance of considering filter class content in the implementation of spawning habitat rehabilitation schemes and when assessing the susceptibility of incubation microhabitats to augmented fine sediment loading to streams.

Franssen, Jan; Lapointe, Michel; Magnan, Pierre

2014-04-01

206

Fine particulate capture device  

NASA Technical Reports Server (NTRS)

To capture fine particulate matter in a gas such as air, a dielectric fluid is directed to the center of whichever face of a rotating disc is exposed to the air flow. The disc is comprised of two or more segments which bear opposite electrostatic potentials. As the dielectric fluid is centrifuged towards the periphery of the rotating disc, the fluid becomes charged to the same potential as the segment over which it is passing. Particulate matter is attracted to the charged segment and is captured by the fluid. The fluid then carries the captured particulate matter to a collection device such as a toroidal container disposed around the periphery of the disc. A grounded electrically-conductive ring may be disposed at the outer periphery of the disc to neutralize the captured particles and the fluid before they enter the container.

Peterson, V. S.; Siewert, R. D. (inventors)

1979-01-01

207

Deposition and remaining productive capabilities of the Upper Cretaceous Eutaw sands of East-Central Mississippi  

SciTech Connect

Nearing the close of the Cretaceous, there were several transgressions and regressions of the epicontinental seas. These rapid changes in sea level played a large part in the depositing and reworking of the Eutaw sands of East-Central Mississippi. The study area includes Jasper, Jones, Clarke and Wayne Counties. The Eutaw sands of this area are described as fine to very fine grained sand which are glauconitic, micaceous and sometimes fossiliferous. This indicates that the environment of deposition was in the neritic zone of the continental shelf. Its high porosities and permeabilities along with its prolific nature makes this formation one of the most sought after reservoirs of the state of Mississippi. All of the 18 Eutaw fields in the study area are closely reaching their economic limits for primary production. Four of these fields have undergone successful waterfloods which have greatly enhanced their ultimate recoveries. The remaining fields in the study area have the potential of yielding millions of barrels of oil from secondary and tertiary recovery methods.

Greer, B.R. [Deepwell Co., Columbia, MS (United States)

1995-10-01

208

Complicated feature of atmospheric aerosols shown in the yellow sand events in Japan  

NASA Astrophysics Data System (ADS)

It is well known that aerosol has a significant potential to the earth's climate. The aerosol distributions in Asia are very complex due to the increasing emissions of small anthropogenic particles associated with economic growth and large dust particles called yellow sands transported on the westerly wind from the continental desert areas. In this study, aerosol properties in the yellow sand events are focused and analyzed from comprehensive aspects. Yellow sand events have often happened in spring. Therefore they have been called 'spring haze' involving an expectation of coming spring to Japan. However the recent yellow sand events are too heavy and too severe to call 'spring haze' due to the increasing of desert areas and contamination with the anthropogenic emissions. The sun/sky photometry has been undertaken at NASA/AERONET stations in Osaka, Shirahama and Noto in Japan. Suspended particulate matter (PM) and OBC (Optical Black Carbon) have been simultaneously measured there. The simultaneous monitoring of aerosols and PM provides such a relation between them as there is a linear correlation between PM concentrations and AOT, which indicates that AOT can be estimated from PM data, and vice versa. It is found that the value of aerosol optical thickness (AOT) during aerosol event is more than double its usual value, and fine anthropogenic particles dominate even during dust events in Japan. It is of interest to mention that yellow sand events in Japan seem to be caused by a mixture of non-absorbing coarse dust and other small haze particles, especially shown in the event in May 2007. A new instrument of NIES/LIDAR network to be set at AERONET/Osaka station in March 2008 is expected to provide us with the vertical distribution of yellow sand particles. Furthermore the model simulations with SPRINTARS/AGCM/CCSR/NIES/FRCGC and satellite data will be available for our better understanding of the beyond pollution of the atmosphere.

Mukai, Sonoyo; Sano, Itaru; Mukai, Makiko

209

Continuous fine ash depressurization system  

DOEpatents

A system for depressurizing and cooling a high pressure, high temperature fine solid particles stream having entrained gas therein. In one aspect, the system has an apparatus for cooling the high pressure, high temperature fine solid particles stream having entrained gas therein and a pressure letdown device for depressurization by separating the cooled fine solid particles from a portion of the fine solid particles stream having entrained gas therein, resulting in a lower temperature, lower pressure outlet of solid particles for disposal or handling by downstream equipment.

Liu, Guohai (Birmingham, AL); Peng, Wan Wang (Birmingham, AL); Vimalchand, Pannalal (Birmingham, AL)

2011-11-29

210

The use of stable isotopes ((13)C/(12)C and (15)N/(14)N) to trace exposure to oil sands processed material in the Alberta oil sands region.  

PubMed

Various oil sands reclamation strategies incorporate oil sands processed material (OSPM) such as mature fine tailings (MFT), engineered tailings (consolidated tailings, CT), and tailings pond water (TPW) into reclamation components that need to develop into viable aquatic ecosystems. The OSPM will contain elevated salinity and organics such as naphthenic acids (NA) and polycyclic aromatic compounds (PAC) that can be chronically toxic to aquatic organisms depending upon levels and age. Due to the complexity of the chemical mixtures, analysis of these compounds in exposed organisms can be challenging. In this study, the stable carbon and nitrogen isotope signatures of selected invertebrates from various types of oil sands reclamation sites were analyzed to determine whether stable isotopes can be used to trace the exposure of aquatic organisms to organic constituents of OSPM. In a series of experimental reclamation ponds of similar age and size, there were trends of (13)C depletion and (15)N enrichment for benthic invertebrates along a gradient of increased levels of MFT and/or TPW. A survey of 16 sites revealed high delta(15)N values for invertebrates in aquatic systems containing MFT and CT (gypsum-treated mixes of MFT and tailings sand), which was attributed to the presence of NH(4)(+), a process by-product in OSPM. Findings of this study indicate a potential for the use of stable nitrogen isotopes to define exposure of biota to OSPM during environmental effects monitoring programs both in surface waters and in cases where groundwater seepage containing oil sands processed water enters surface receiving environments in the region. PMID:19199145

Farwell, A J; Nero, V; Ganshorn, K; Leonhardt, C; Ciborowski, J; MacKinnon, M; Dixon, D G

2009-01-01

211

Beer Bike Violations & Fines 2012 # Water/Balloon Violations Fine  

E-print Network

Beer Bike Violations & Fines 2012 # Water/Balloon Violations Fine 1 Consistent under-filling of water balloons (assessed by the Parade or Security Area Coordinators) $1,500 (assessed against the violating college) 2 Filling balloons with any substance but water $1,500 per offense 3 Hitting Beer Bike

212

The effect of limited availability of N or water on C allocation to fine roots and annual fine root turnover in Alnus incana and Salix viminalis.  

PubMed

The effect of limited nitrogen (N) or water availability on fine root growth and turnover was examined in two deciduous species, Alnus incana L. and Salix viminalis L., grown under three different regimes: (i) supply of N and water in amounts which would not hamper growth, (ii) limited N supply and (iii) limited water supply. Plants were grown outdoors during three seasons in covered and buried lysimeters placed in a stand structure and filled with quartz sand. Computer-controlled irrigation and fertilization were supplied through drip tubes. Production and turnover of fine roots were estimated by combining minirhizotron observations and core sampling, or by sequential core sampling. Annual turnover rates of fine roots <1 mm (5-6 year(-1)) and 1-2 mm (0.9-2.8 year(-1)) were not affected by changes in N or water availability. Fine root production (<1 mm) differed between Alnus and Salix, and between treatments in Salix; i.e., absolute length and biomass production increased in the order: water limited < unlimited < N limited. Few treatment effects were detected for fine roots 1-2 mm. Proportionally more C was allocated to fine roots (?2 mm) in N or water-limited Salix; 2.7 and 2.3 times the allocation to fine roots in the unlimited regime, respectively. Estimated input to soil organic carbon increased by ca. 20% at N limitation in Salix. However, future studies on fine root decomposition under various environmental conditions are required. Fine root growth responses to N or water limitation were less pronounced in Alnus, thus indicating species differences caused by N-fixing capacity and slower initial growth in Alnus, or higher fine root plasticity in Salix. A similar seasonal growth pattern across species and treatments suggested the influence of outer stimuli, such as temperature and light. PMID:23963409

Rytter, Rose-Marie

2013-09-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

214

Sustainable agriculture and nitrogen reduction: an open field experiment using natural zeolitites in silty-clay reclaimed soil at Codigoro (Po River Delta, Ferrara, Italy)  

NASA Astrophysics Data System (ADS)

Following the guidelines of Nitrate and Water Framework Directives (91/676/CEE, 200/60/CE) an innovative integrated zeolitite cycle is being tested on a reclaimed clayey-silt soil in the Po Delta area (Ferrara Province, Italy), in the framework of the EU-funded ZeoLIFE project (LIFE+10 ENV/IT/000321). Natural zeolitites are pyroclastic rocks containing more than 50% of zeolites, a kind of hydrous minerals with peculiar physical and chemical properties, like high and selective cation exchange capacity (CEC), molecular adsorption and reversible dehydration. Zeolitites can trap NH4+ from solutions and release it gradually to the plant roots once they have been mixed in agricultural soils, allowing both fertilization and irrigation reduction and improvement of the yield. The fertilization reduction can result in a decrease of the nitrate content in groundwater and surface waters, ultimately leading to a mitigation of nutrient excess in the environment. Similarly, reduction of irrigation water means a minor exploitation of the water resource. The selected material used in the project is a chabazite zeolitite coming from a quarry near Sorano in Central Italy (Bolsena volcanic district). The open-field experimentation foresees two year of cultivation. A surface of about 6 ha has been divided into six parcels: three control parcels are cultivated and irrigated in traditional way; two parcels have been added with coarse-grained (ø = 3- 6 mm) natural zeolitite at different zeolitite/soil ratios (5 kg/m2 and 15 kg/m2) and one has been mixed with fine-grained (ø < 3 mm) NH4+-charged zeolitite at 10 kg/m2. Zeolitite/soil ratios have been determined upon a series of greenhouse tests, and the ammonium enriched material is obtained by cation exchange with swine manure in a specifically conceived prototype. The environmental quality of soil and water in each parcel is monitored by periodic soil, groundwater and porewater analyses. Soil EC, temperature and volumetric water content are continuously measured with probes at different depth (5-30-50-100-150 cm). The quality of surface water is checked by analyzing the outflow from the drains of the sub-irrigation system installed in the field. An automated meteorological station has been also installed in order to quantify rainfalls and sun irradiation for water balance calculation. During the first year, a no-food variety of sorghum has been cultivated. In the parcels treated with natural zeolitite and in that bearing NH4+-charged zeolitite, the fertilization has been reduced by 30% and 50% with respect to the controls. Notwithstanding these reductions, the yield increased by 5% and 15% in the parcel added with natural zeolitite and in that treated with NH4+-charged zeolitite, respectively. As confirmed by previously performed laboratory leaching tests, NH4+ in porewater and surface water was comparable in all parcels (

Faccini, Barbara; Di Giuseppe, Dario; Mastrocicco, Micòl; Coltorti, Massimo; Colombani, Nicolò; Ferretti, Giacomo

2014-05-01

215

Petrophysical Analysis of Oil Sand in Athabasca  

NASA Astrophysics Data System (ADS)

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

cheong, S.; Lee, H.

2013-12-01

216

The day the sands caught fire.  

NASA Astrophysics Data System (ADS)

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

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

1998-11-01

217

Retrieval of sand density from hyperspectral BRDF  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

218

New developments in slow sand filtration  

SciTech Connect

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

Fox, K.R.

1993-01-01

219

Seismic wave velocity of hydrate-bearing fine-grained sediments sampled from the Ulleung basin in East Sea, Korea  

NASA Astrophysics Data System (ADS)

Synthesizing gas hydrate in a fine-grained natural seabed sediment sample, mainly composed of silty-to-clayey soils, has been hardly attempted due to the low permeability. It has been known that hydrate loci in pore spaces and heterogeneity of hydrate growth in core-scale play a critical role in determining physical properties of hydrate-bearing sediments. In the presented study, we attempted to identify the effect of hydrate growth morphology on seismic velocities in natural fine-grained sediments sampled from the Ulleung Basin in East Sea. We synthesized CO2 hydrate in clayey silt sediments in an instrumented oedometric cell and measured seismic velocities during hydrate formation and loading processes. Herein, we present the experiment results on P-wave and S-wave velocities of gas hydrate-bearing fine-grained sediments. It is found that the geophysical properties of gas hydrate-bearing sediments are governed by hydrate saturation and effective stress as well as morphological feature of hydrate formation in sediments.

Kim, H.; Kwon, T.; Cho, G.

2012-12-01

220

Hydrothermal deformation of granular quartz sand  

Microsoft Academic Search

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

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

2008-01-01

221

Methanogenic potential of tailings samples from oil sands extraction plants  

Microsoft Academic Search

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

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

2002-01-01

222

Treatment Efficiencies of Slow Sand Filtration for Landscape Water  

Microsoft Academic Search

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

Cui Li; Yifan Wu; Liangbo Zhang; Wen Liu

2010-01-01

223

www.nasa.gov WHITE SANDS MISSILE RANGE ACCESS CAPABILITIES  

E-print Network

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

224

Slow Sand Filtration: Influences of Selected Process Variables  

Microsoft Academic Search

Biological activity within the sand bed had the strongest influence on removal efficiency of total coliform bacteria by slow sand filtration, as determined by six pilot filters (shown above). Temperature, sand bed depth, and sand size also had strong influence. La actividad biológica dentro de la cama de arena ejerce la influencia más grande en la eficiencia de la extracción

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

1985-01-01

225

Hierarchical analysis of genetic structure in the habitat-specialist Eastern Sand Darter (Ammocrypta pellucida)  

PubMed Central

Quantifying spatial genetic structure can reveal the relative influences of contemporary and historic factors underlying localized and regional patterns of genetic diversity and gene flow – important considerations for the development of effective conservation efforts. Using 10 polymorphic microsatellite loci, we characterize genetic variation among populations across the range of the Eastern Sand Darter (Ammocrypta pellucida), a small riverine percid that is highly dependent on sandy substrate microhabitats. We tested for fine scale, regional, and historic patterns of genetic structure. As expected, significant differentiation was detected among rivers within drainages and among drainages. At finer scales, an unexpected lack of within-river genetic structure among fragmented sandy microhabitats suggests that stratified dispersal resulting from unstable sand bar habitat degradation (natural and anthropogenic) may preclude substantial genetic differentiation within rivers. Among-drainage genetic structure indicates that postglacial (14 kya) drainage connectivity continues to influence contemporary genetic structure among Eastern Sand Darter populations in southern Ontario. These results provide an unexpected contrast to other benthic riverine fish in the Great Lakes drainage and suggest that habitat-specific fishes, such as the Eastern Sand Darter, can evolve dispersal strategies that overcome fragmented and temporally unstable habitats.

Ginson, Robert; Walter, Ryan P; Mandrak, Nicholas E; Beneteau, Courtney L; Heath, Daniel D

2015-01-01

226

Burrowing inhibition by fine textured beach fill: Implications for recovery of beach ecosystems  

NASA Astrophysics Data System (ADS)

Beach nourishment is often considered the most environmentally sound method of maintaining eroding shorelines. However, the ecological consequences are poorly understood. Fill activities cause intense disturbance and high mortality and have the potential to alter the diversity, abundance, and distribution of intertidal macroinvertebrates for months to years. Ecological recovery following fill activities depends on successful recolonization and recruitment of the entire sandy intertidal community. The use of incompatible sediments as fill material can strongly affect ecosystem recovery. We hypothesized that burrowing inhibition of intertidal animals by incompatible fine fill sediments contributes to ecological impacts and limits recovery in beach ecosystems. We experimentally investigated the influence of intertidal zone and burrowing mode on responses of beach invertebrates to altered sediment texture (28-38% fines), and ultimately the potential for colonization and recovery of beaches disturbed by beach filling. Using experimental trials in fill material and natural beach sand, we found that the mismatched fine fill sediments significantly inhibited burrowing of characteristic species from all intertidal zones, including sand crabs, clams, polychaetes, isopods, and talitrid amphipods. Burrowing performance of all five species we tested was consistently reduced in the fill material and burrowing was completely inhibited for several species. The threshold for burrowing inhibition by fine sediment content in middle and lower beach macroinvertebrates varied by species, with highest sensitivity for the polychaete (4% fines, below the USA regulatory limit of 10% fines), followed by sand crabs and clams (20% fines). These results suggest broader investigation of thresholds for burrowing inhibition in fine fill material is needed for beach animals. Burrowing inhibition caused by mismatched fill sediments exposes beach macroinvertebrates to stresses, which could depress recruitment and survival at all intertidal zones. Our results suggest use of incompatible fine fill sediments from dredging projects creates unsuitable intertidal habitat that excludes burrowing macroinvertebrates and could delay beach ecosystem recovery. Through effects on beach invertebrates that are prey for shorebirds and fish, the ecological impacts of filling with mismatched fine sediments could influence higher trophic levels and extend beyond the beach itself.

Viola, Sloane M.; Hubbard, David M.; Dugan, Jenifer E.; Schooler, Nicholas K.

2014-10-01

227

Morphology and formation of the upwind margin at White Sands Dune Field  

NASA Astrophysics Data System (ADS)

A remarkable transitional landscape occurs at the upwind margin of White Sands Dune Field. Over the course a few hundred meters the landscape changes from an flat, sand availability-limited playa, to a sand sheet with strong spatial grain-size sorting, to meter high slipfaceless proto-dunes and finally to several meter high dunes with angle-of-repose slip faces. Within one wavelength of the first dune, dunes rise to nearly 10 meters in height above Alkali Flat, the upwind playa that extends for 13 km westward from the dune field. This abrupt rise in topography may perturb the dominant southwesterly wind flow and trigger an internal boundary layer, which causes a spatial decrease in surface wind stress and decline sediment flux, thereby altering the dune dynamics and dune field morphology downwind. Though the emergence of this upwind transition may play a key role in the morphodynamics of the dune field, what are the morphodynamics of the transition? What are the feedbacks between the emerging topography and the wind within the transition? This presentation uses high-resolution aerial photos, time-series airborne LiDAR and terrestrial laser scanning to characterize the transitional morphology the upwind margin of White Sands and discusses these morphologies in the context of the interplay between wind flow and dune field topography. Alkali Flat playa is sparsely sand covered, the amount of which varies temporally. The sparse sand cover occurs as sand patches that form in the lee of bushes or within topographic lows generated by deflated gypsum crust. Adjacent and downwind of the playa is a sand sheet composed of variable wavelength, coarse grained ripples. Ten to thirty meter wide ripple patches organized into a repeating sequence of coarse-grained, > 15 cm wavelength ripples to fine-grained, < 15 cm wavelength ripples occur across the sand sheet. Downwind the ripple patches organize into low-relief protodune hummocks. The protodunes are covered by a range of ripple sizes that are spatially organized similar to the ripple patches within the sand sheet. The coarsest-grained, largest wavelength ripples occur at the protodune crest and fine downwind. The inter-protodune areas are typically free of sand, exposing indurated dune stratigraphy. The protodunes grow in height, but the wavelength remains ~ 70 m downwind until a slipface develops. Rapid growth into 5-10 meter high dunes occurs within one wavelength after slipface development and generates an abrupt topographic increase in topography. Dune migration rates are approximately 6 m/year at the upwind margin and decline to around 3 m/year within a few kilometers of the upwind margin. A generalized model of dune emergence at the upwind margin of dune fields is proposed using examples from other dune fields.

Ewing, R. C.; Jerolmack, D. J.; Martin, R. L.; Reitz, M. D.; Phillips, C. B.; Falcini, F.; Masteller, C.

2012-12-01

228

Can in situ methanogenesis explain a 3 m-thick gas hydrate-filled sand in Walker Ridge Block 313, Gulf of Mexico?  

NASA Astrophysics Data System (ADS)

In the spring of 2009, the Gulf of Mexico Gas Hydrate Joint Industry Project (JIP) Leg II drilled several holes in the Gulf of Mexico in the search for gas hydrate-filled reservoirs. In Walker Ridge Block 313, Hole H was drilled in a location where the gas hydrate stability zone (GHSZ) extended over 800 meters below seafloor (mbsf). For this research, we will focus on gas hydrate found in Hole H in a thick accumulation in fine-grained sediments (180-320 mbsf) as well as in a 3 m sand (292-295 mbsf). In the thick fine-grained accumulation, logging-while-drilling resistivity images show gas hydrate occurs predominately as fill in near-vertical fractures (dipping 77 degrees on average). Gas hydrates are likely to occupy 5 or 10% of the total pore volume in the fractured interval. No electrically conductive (water-filled fractures) were identified in the gas hydrate-filled fracture interval or elsewhere in Hole H. The fractures occur regularly throughout the 180-320 mbsf interval, except between 282-302 mbsf, where no fractures appear. A 3 m-thick gas hydrate-filled sand occurs in the middle of the fracture hiatus, from 292-295 mbsf. The 3 m sand has an approximate gas hydrate saturation of 70% of pore space, much higher than the fractures. Other JIP scientists have traced this 3 m-thick sand on 3D seismic sections, and found that it intersects the base of the GHSZ approximately 3 km downdip. In addition, the intersection between the sand and the gas hydrate stability zone has a reflection phase reversal, suggesting that the sand may contain gas hydrate over 3 km. Could the gas that supplies the 3 m sand have traveled updip through the GHSZ in the 3 m sand? Alternatively, the gas that supplies the sand and the fractures may be formed in place by in situ methanogenesis. Dissolved methane may diffuse from the surrounding fine-grained sediments into the sand, increasing the concentration of gas hydrate in the sand, while leaving surrounding fine-grained sediments devoid of gas hydrate. Similar situations - where gas hydrates form in coarse-grained layers but not in surrounding fine-grained sediments - are found in several locations worldwide. In this research, we are building a 1-dimensional diagenetic model that reproduces the conditions at Hole H. The model will test if enough biogenic methane is present to fill the 3 m-thick sand to the observed gas hydrate saturation. Additionally, this model will determine if the hiatus in gas hydrate-bearing fractures surrounding the sand can be explained by diffusion of methane from the fine-grained sediments into the sand.

Cook, A.; Malinverno, A.

2010-12-01

229

Studies on use of Copper Slag as Replacement Material for River Sand in Building Constructions  

NASA Astrophysics Data System (ADS)

This work focuses on the use of copper slag, as a partial replacement of sand for use in cement concrete and building construction. Cement mortar mixtures prepared with fine aggregate made up of different proportions of copper slag and sand were tested for use as masonry mortars and plastering. Three masonry wall panels of dimensions 1 × 1 m were plastered. The studies showed that although copper slag based mortar is suitable for plastering, with the increase in copper slag content, the wastage due to material rebounding from the plastered surfaces increases. It is therefore suggested that the copper slag can be used for plastering of floorings and horizontal up to 50 % by mass of the fine aggregate, and for vertical surfaces, such as, brick/block walls it can be used up to 25 %. In this study on concrete mixtures were prepared with two water cement ratios and different proportions of copper slag ranging from 0 % (for the control mix) to 100 % of fine aggregate. The Concrete mixes were evaluated for workability, density, and compressive strength.

Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Rajamane, N. P.

2014-09-01

230

Tidal sands as biogeochemical reactors  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

231

Layers, Landslides, and Sand Dunes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 27 October 2003

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

Image information: VIS instrument. Latitude -14.1, Longitude 306.7 East (53.3 West). 19 meter/pixel resolution.

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

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

2003-01-01

232

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

Microsoft Academic Search

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

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

2006-01-01

233

The accumulation of nitrosyl ruthenium by fine particles and marine organisms  

Microsoft Academic Search

The accumulation of nitrosyl ruthenium lo0 by fine particles, algae and animals from sea water is described. The presence of ferric hydroxide on the sand and silt particles enhances RuloG accumulation. Uptake of Ru loG by marinc algae is a surface phenomenon associated with the extra-cellular polysaccharide material. Fish accumulate the nuclidc principally in the gut, gills and skin. In

RAYMOND F. JONES

1960-01-01

234

Provenance and recycling of Arabian desert sand  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

235

Provenance and recycling of Arabian desert sand  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

236

Applying NMR spin-echo logging to Shaly Sand Formation evaluation: Case studies of Rocky Mountain region gas wells  

Microsoft Academic Search

Conventional wireline logs often fail to provide a reliable evaluation of reservoir quality and producibility in shaly mud formations, particularly in the shaly gas sand reservoirs of the Rocky Mountains which are characterized by low porosity (i.e., <15 pu), low permeability (0.1 to 1 md), very fine grain size, and high irreducible water saturations. A new-generation nuclear magnetic resonance (NMR)

R. K. Ladtkow; B. J. Stambaugh; D. Mardon

1995-01-01

237

Provenance and glacial history of very fine quartz sand from the Weddell Sea, Antarctica  

E-print Network

, 1967). B. Distribution of surficial sediments in the Weddell Sea (modified fram Anderson, 1972). Table 1. Criteria for distinguishing basal tills, glacial marine and mass flow deposits (modified from Anderson, 1985). SUIJTLE, I F PRESENT CRUDELY 10... sedimentation pattern (fram Hays, 1967). B. Distribution of surficial sediments in the Weddell Sea (modified from Anderson, 1972). 29 17 A. D/V JQIIIES ILexajxt11xln prOfile, dip section, showing the major reflectors and their correlation to lithostratigraphy...

Smith, Caryn Hallett

2012-06-07

238

Effect of sediment concentration on artificial well recharge in a fine sand aquifer  

E-print Network

abandonment of wells; 5. increase municipal expansion resulting from subsurface water supplies; 6. prevent sea water intrusion into coastal aquifers; 7. prevent dewatering of all or part of the under- ground reservoirs; 8. prevent release of deep... developed using the so-called Dupuit assumptions and is based on the solution of Laplace's equation as applied to the velocity potential at any point in the aquifer (19, 29, 36). The Dupuit assumptions are: (a) the velocity of the flow is proportional...

Rahman, Mohammed Ataur

1968-01-01

239

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

ERIC Educational Resources Information Center

Continental geology and tectonics are explored through this study of modern beach sands of South America. This report assesses how well petrographic studies of sandstones can recreate continental geography. Data on the petrography of 218 modern South American beach sands are presented and analyzed. The five major mineral associations of light…

Potter, Paul Edwin

1986-01-01

240

Threshold for Sand Mobility on Mars Calibrated from Seasonal Variations of Sand Flux  

NASA Astrophysics Data System (ADS)

The sand flux and its seasonal variation at Nili Patera dune field are measured from a time-series of HiRISE images. A threshold for sand mobility is constrained from these measurements and the wind predictions from GCM simulations.

Ayoub, F.; Avouac, J. P.; Newman, C. E.; Richardson, M. I.; Lucas, A.; Leprince, S.; Bridges, N. T.

2014-07-01

241

Barley, a potential species for initial reclamation of saline composite tailings of oil sands.  

PubMed

The oil sands industry in Alberta (Canada) has developed the composite tailings (CT) process to reduce the fluid fine tails resulting from the processing of oil sands. This process uses a chemical coagulant (gypsum or alum) to produce aggregated fines (clay), so they are retained with the coarse sand fraction of the extraction tailings to form CT, from which fines-free water is released relatively quickly compared with untreated tailings. The resulting CT and CT waters are saline-sodic, with Na+, SO4(2-), and Cl- being the dominant ions. When freshly deposited, the CT deposits are too soft for access by reclamation equipment, and the time required for these deposits to remove the water sufficiently to support traffic is uncertain. A greenhouse study was designed to determine the suitability of barley (Hordeum vulgare L.) for reclamation of fresh CT deposits and to evaluate benefits of peat amendments. This study assessed germination, early plant growth, chlorophyll content, and survival of barley growing in alum- and gypsum-treated CT, with and without peat amendment. Ion and trace metal accumulation in the root and shoot tissues of barley was determined. Amendment of CT with peat improved germination, survival, and growth of barley, but did not prevent leaf injury (probably due to Na and Cl- and possibly multiple nutrient deficiency). Field studies will be undertaken to validate our greenhouse results suggesting that barley could be used to improve dewatering of the freshly deposited substrates, reduce soil erosion, and facilitate leaching of ions by root penetration into the substrate. PMID:14674548

Renault, Sylvie; MacKinnon, Mike; Qualizza, Clara

2003-01-01

242

Uprated fine guidance sensor study  

NASA Technical Reports Server (NTRS)

Future orbital observatories will require star trackers of extremely high precision. These sensors must maintain high pointing accuracy and pointing stability simultaneously with a low light level signal from a guide star. To establish the fine guidance sensing requirements and to evaluate candidate fine guidance sensing concepts, the Space Telescope Optical Telescope Assembly was used as the reference optical system. The requirements review was separated into three areas: Optical Telescope Assembly (OTA), Fine Guidance Sensing and astrometry. The results show that the detectors should be installed directly onto the focal surface presented by the optics. This would maximize throughput and minimize point stability error by not incoporating any additional optical elements.

1984-01-01

243

'RAT' Leaves a Fine Mess  

NASA Technical Reports Server (NTRS)

This graph shows the light signatures, or spectra, of two sides of the rock dubbed 'Bounce,' located at Meridiani Planum, Mars. The spectra were taken by the miniature thermal emission spectrometer on the Mars Exploration Rover Opportunity. The left side of this rock is covered by fine dust created when the rover drilled into the rock with its rock abrasion tool. These 'fines' produce a layer of pyroxene dust that can be detected here in the top spectrum. The right side of the rock has fewer fines and was used to investigate the composition of this basaltic rock.

2004-01-01

244

36 CFR 910.35 - Fine arts.  

Code of Federal Regulations, 2013 CFR

...Property 3 2013-07-01 2012-07-01 true Fine arts. 910.35 Section 910.35 Parks, Forests, and...Applicable to the Development Area § 910.35 Fine arts. Fine arts, including sculpture, paintings, decorative...

2013-07-01

245

36 CFR 910.35 - Fine arts.  

Code of Federal Regulations, 2012 CFR

... 3 2012-07-01 2012-07-01 false Fine arts. 910.35 Section 910.35 Parks, Forests, and...Applicable to the Development Area § 910.35 Fine arts. Fine arts, including sculpture, paintings, decorative...

2012-07-01

246

36 CFR 910.35 - Fine arts.  

Code of Federal Regulations, 2011 CFR

... 3 2011-07-01 2011-07-01 false Fine arts. 910.35 Section 910.35 Parks, Forests, and...Applicable to the Development Area § 910.35 Fine arts. Fine arts, including sculpture, paintings, decorative...

2011-07-01

247

36 CFR 910.35 - Fine arts.  

... 3 2014-07-01 2014-07-01 false Fine arts. 910.35 Section 910.35 Parks, Forests, and...Applicable to the Development Area § 910.35 Fine arts. Fine arts, including sculpture, paintings, decorative...

2014-07-01

248

36 CFR 910.35 - Fine arts.  

Code of Federal Regulations, 2010 CFR

... 3 2010-07-01 2010-07-01 false Fine arts. 910.35 Section 910.35 Parks, Forests, and...Applicable to the Development Area § 910.35 Fine arts. Fine arts, including sculpture, paintings, decorative...

2010-07-01

249

Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico  

SciTech Connect

A unique set of high-quality downhole shallow subsurface well log data combined with industry standard 3D seismic data from the Alaminos Canyon area has enabled the first detailed description of a concentrated gas hydrate accumulation within sand in the Gulf of Mexico. The gas hydrate occurs within very fine grained, immature volcaniclastic sands of the Oligocene Frio sand. Analysis of well data acquired from the Alaminos Canyon Block 818 No.1 ('Tigershark') well shows a total gas hydrate occurrence 13 m thick, with inferred gas hydrate saturation as high as 80% of sediment pore space. Average porosity in the reservoir is estimated from log data at approximately 42%. Permeability in the absence of gas hydrates, as revealed from the analysis of core samples retrieved from the well, ranges from 600 to 1500 millidarcies. The 3-D seismic data reveals a strong reflector consistent with significant increase in acoustic velocities that correlates with the top of the gas-hydrate-bearing sand. This reflector extends across an area of approximately 0.8 km{sup 2} and delineates the minimal probable extent of the gas hydrate accumulation. The base of the inferred gas-hydrate zone also correlates well with a very strong seismic reflector that indicates transition into units of significantly reduced acoustic velocity. Seismic inversion analyses indicate uniformly high gas-hydrate saturations throughout the region where the Frio sand exists within the gas hydrate stability zone. Numerical modeling of the potential production of natural gas from the interpreted accumulation indicates serious challenges for depressurization-based production in settings with strong potential pressure support from extensive underlying aquifers.

Boswell, R.D.; Shelander, D.; Lee, M.; Latham, T.; Collett, T.; Guerin, G.; Moridis, G.; Reagan, M.; Goldberg, D.

2009-07-15

250

Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico  

USGS Publications Warehouse

A unique set of high-quality downhole shallow subsurface well log data combined with industry standard 3D seismic data from the Alaminos Canyon area has enabled the first detailed description of a concentrated gas hydrate accumulation within sand in the Gulf of Mexico. The gas hydrate occurs within very fine grained, immature volcaniclastic sands of the Oligocene Frio sand. Analysis of well data acquired from the Alaminos Canyon Block 818 #1 ("Tigershark") well shows a total gas hydrate occurrence 13??m thick, with inferred gas hydrate saturation as high as 80% of sediment pore space. Average porosity in the reservoir is estimated from log data at approximately 42%. Permeability in the absence of gas hydrates, as revealed from the analysis of core samples retrieved from the well, ranges from 600 to 1500 millidarcies. The 3-D seismic data reveals a strong reflector consistent with significant increase in acoustic velocities that correlates with the top of the gas-hydrate-bearing sand. This reflector extends across an area of approximately 0.8??km2 and delineates the minimal probable extent of the gas hydrate accumulation. The base of the inferred gas-hydrate zone also correlates well with a very strong seismic reflector that indicates transition into units of significantly reduced acoustic velocity. Seismic inversion analyses indicate uniformly high gas-hydrate saturations throughout the region where the Frio sand exists within the gas hydrate stability zone. Numerical modeling of the potential production of natural gas from the interpreted accumulation indicates serious challenges for depressurization-based production in settings with strong potential pressure support from extensive underlying aquifers.

Boswell, R.; Shelander, D.; Lee, M.; Latham, T.; Collett, T.; Guerin, G.; Moridis, G.; Reagan, M.; Goldberg, D.

2009-01-01

251

Experimental Investigation of Concrete with Combined High alumina cement, Silica fume and M-Sand  

NASA Astrophysics Data System (ADS)

Concrete is by far the most widely used construction material today. It is estimated that present consumption of concrete in the world is of the order of 10 billion tonnes every year. The cement industry is responsible for about 6% of all CO2 emissions. So nowadays there is a great interest in the development and implementation of various alternatives to Portland cement as a binder in concrete and also alternatives to fine and coarse aggregates in concrete to reduce the energy used in production of Portland cement clinker and the associated greenhouse gas emission and also for reducing resources consumption by proper recycling. This research work is carried out in order to explore the effect of various replacement percentages of cement by combined High alumina cement with silica fume and also the fine aggregate is fully replaced with manufacturing sand. Conclusion is made based on the comparison between the performance of blended cement concrete and conventional concrete.

Joseph, Dona Maria; Devi, Manjula; Senthilkumar, S.

2013-03-01

252

Environmental differences in substrate mechanics do not affect sprinting performance in sand lizards (Uma scoparia and Callisaurus draconoides).  

PubMed

Running performance depends on a mechanical interaction between the feet of an animal and the substrate. This interaction may differ between two species of sand lizard from the Mojave Desert that have different locomotor morphologies and habitat distributions. Uma scorparia possesses toe fringes and inhabits dunes, whereas the closely related Callisaurus draconoides lacks fringes and is found on dune and wash habitats. The present study evaluated whether these distribution patterns are related to differential locomotor performance on the fine sand of the dunes and the course sand of the wash habitat. We measured the kinematics of sprinting and characterized differences in grain size distribution and surface strength of the soil in both habitats. Although wash sand had a surface strength (15.4±6.2 kPa) that was more than three times that of dune sand (4.7±2.1 kPa), both species ran with similar sprinting performance on the two types of soil. The broadly distributed C. draconoides ran with a slightly (22%) faster maximum speed (2.2±0.2 m s(-1)) than the dune-dwelling U. scorparia (1.8±0.2 m s(-1)) on dune sand, but not on wash sand. Furthermore, there were no significant differences in maximum acceleration or the time to attain maximum speed between species or between substrates. These results suggest that differences in habitat distribution between these species are not related to locomotor performance and that sprinting ability is dominated neither by environmental differences in substrate nor the presence of toe fringes. PMID:21147976

Korff, Wyatt L; McHenry, Matthew J

2011-01-01

253

Palynofacies of lignites and associated sediments in the upper paleocene Tuscahoma sand of southwestern Alabama and eastern Mississippi  

SciTech Connect

The Tuscahoma Sand of the Wilcox Group is composed of fine-grained sand, laminated sandy clay, marl and lignite. The Tuscahoma forms a poorly exposed belt from southeastern Alabama and extends northwestward into western Alabama and eastern Mississippi. The sand is assigned to the late Paleocene planktonic foraminiferal Morozovella velascoensis interval zone. Lignites in the Tuscahoma Sand occur as parasequence deposits in the highstand systems tract of a type 2 depositional sequence near the top of the formation. Organic debris associated with these highstand-systems-tract deposits is dominated by land-derived plant tissues. Marine influence is evidenced by the rare occurrence of dinoflagellate cysts, microforminiferal test linings, and the presence of gray, amorphous organic matter. Three palynofacies are recognized within highstand-systems-tract deposits in the upper Tuscahoma Sand based on the occurrence of organic debris. These palynofacies represent freshwater swamp, brackish marsh and marginal- to shallow-water marine depositional environments. Lignites in the Tuscahoma Sand are dominated by an angiosperm pollen assemblage. Gymnosperm pollen is rare, and marine forms are absent. This assemblage reflects deposition under fresh-water swamp conditions. Carbonaceous clay samples vary in the composition of organic debris. However, many are characterized by the occurrence of herbaceous angiosperm pollen. Arborescent angiosperm pollen is common, as are fern spores. Bisaccate conifer pollen is common and dinoflagellate cysts are rare. Fungal elements are abundant and woody tissue commonly is more degraded than in lignite samples. This assemblage represents deposition in coastal, brackish marsh environments. Organic debris in laminated clays, silts, and sands typically have angiosperm and gymnosperm pollen, dinoflagellate cysts, degraded terrestrial plant material, and amorphous organic matter, and represent shallow-marine and marginal-marine deposits.

Carroll, R.E. (Geological Survey of Alabama, Tuscaloosa, AL (United States))

1993-09-01

254

Flocculation settling characteristics of mud: sand mixtures  

NASA Astrophysics Data System (ADS)

When natural muds become mixed with sandy sediments in estuaries, it has a direct effect on the flocculation process and resultant sediment transport regime. Much research has been completed on the erosion and consolidation of mud/sand mixtures, but very little is known quantitatively about how mixed sediments interact whilst in suspension, particularly in terms of flocculation. This paper presents the settling velocity findings from a recent laboratory study which examined the flocculation dynamics for three different mud/sand mixtures at different concentrations (0.2-5 g.l-1) and turbulent shear stresses (0.06-0.9 Pa) in a mini-annular flume. The low intrusive video-based Laboratory Spectral Flocculation Characteristics instrument was used to determine floc/aggregate properties (e.g., size, settling velocity, density and mass) for each population. Settling data was assessed in terms of macrofloc (>160 ?m) and microfloc (<160 ?m) settling parameters: Wsmacro and Wsmicro, respectively. For pure muds, the macroflocs are regarded as the most dominant contributors to the total depositional flux. The parameterised settling data indicates that by adding more sand to a mud/sand mixture, the fall velocity of the macrofloc fraction slows and the settling velocity of microflocs quickens. Generally, a mainly sandy suspension comprising 25% mud and 75% sand (25M:75S), will produce resultant Wsmacro which are slower than Wsmicro. The quickest Wsmicro appears to consistently occur at a higher level of turbulent shear stress (? ˜ 0.6 Pa) than both the macrofloc and microfloc fractions from suspensions of pure natural muds. Flocculation within a more cohesively dominant muddy-sand suspension (i.e., 75M:25S) produced macroflocs which fell at similar speeds (±10%) to pure mud suspensions at both low (200 mg l-1) and intermediate (1 g l-1) concentrations at all shear stress increments. Also, low sand content suspensions produced Wsmacro values that were faster than the Wsmicro rates. In summary, the experimental results of the macrofloc and microfloc settling velocities have demonstrated that flocculation is an extremely important factor with regards to the depositional behaviour of mud/sand mixtures, and these factors must be considered when modelling mixed sediment transport in the estuarine or marine environment.

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

2010-04-01

255

Wind profiles on the stoss slope of sand dunes: Implications for eolian sand transport  

SciTech Connect

Starting with the work of R.A. Bagnold it has been recognized that the shear stress exerted by the wind on sand grains is the driving force for eolian sand transport. Calculation of accurate rates of sand transport is essential for prediction of migration rates of sand dunes in modern environments as well as reconstructing paleoclimates (wind speed and direction) from eolian deposits. Because a sand dune is a streamlined obstacle in the path of the wind, continuity necessitates that the flow field is compressed over the windward side of a dune and shear stress should progressively increase up the slope as the flow accelerates. However, airflow measurements over 14 dunes (at White Sands, New Mexico; Algodones, CA; and Padre Island, TX) show that compression of the flow field occurs very close to the surface and as a consequence, the overlying flow actually shows an overall decrease in shear stress up the slope. Measurements commonly collected in the overlying zone are not representative of the near-surface, sand-driving wind. Furthermore, near-surface compression of the flow field implies that a pressure gradient exists that would render the current transport models inappropriate for sloping surfaces that dominate natural sandy desert terrains.

Frank, A.; Kocurek, G. (Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences)

1993-04-01

256

Threshold for sand mobility on Mars calibrated from seasonal variations of sand flux  

NASA Astrophysics Data System (ADS)

Coupling between surface winds and saltation is a fundamental factor governing geological activity and climate on Mars. Saltation of sand is crucial for both erosion of the surface and dust lifting into the atmosphere. Wind tunnel experiments along with measurements from surface meteorology stations and modelling of wind speeds suggest that winds should only rarely move sand on Mars. However, evidence for currently active dune migration has recently accumulated. Crucially, the frequency of sand-moving events and the implied threshold wind stresses for saltation have remained unknown. Here we present detailed measurements of Nili Patera dune field based on High Resolution Imaging Science Experiment images, demonstrating that sand motion occurs daily throughout much of the year and that the resulting sand flux is strongly seasonal. Analysis of the seasonal sand flux variation suggests an effective threshold for sand motion for application to large-scale model wind fields (1–100?km scale) of ?s=0.01±0.0015?N?m?2.

Ayoub, F.; Avouac, J.-P.; Newman, C. E.; Richardson, M. I.; Lucas, A.; Leprince, S.; Bridges, N. T.

2014-09-01

257

Yellow perch embryo-larval survival and growth in surface waters associated with oil-sands mining  

SciTech Connect

As part of their land reclamation strategy, Syncrude Canada Ltd. is currently developing environmentally acceptable tailings disposal methods. Fine tailings, a suspension of clay and residual bitumen, is the waste product from oil sands extraction. Fine-tailings contain naphthenic acids, a group of saturated aliphatic and alicyclic carboxylic acids, which occur naturally in petroleum and are partly responsible for the toxicity of process water. The wet landscape method involves covering fine tails with a layer of water such that a self-sustaining ecosystem can be established. A 5 ha demonstration pond with a bottom of fine-tailings was constructed and stocked with yellow perch for experimental purposes. Two other reclaimed ponds formed with oil-sands overburden material were also stocked with perch. Adult perch sampled in the fall of 1995 from the experimental and reclaimed ponds exhibited a 2-fold induction of MFO activity compared to the source lake; indicating organic compound exposure. Perch from one of the reclaimed ponds showed significantly reduced circulating reproductive hormone levels, gonad size and smaller ovarian follicles. Reproductive parameters were not different between the source lake and the remaining ponds. Paired lab and field experiments were conducted to determine if contaminants present would be detrimental to egg viability and development of larvae either through direct exposure of spawned eggs or indirectly by effecting oogenesis. An early life stage toxicity test was also performed using commercially available naphthenic acid standard. Endpoints measured were percent fertilization, percent hatch, mortality, deformities, timing of developmental periods and larval growth.

Peters, L.E.; Heuvel, M.R. van den; Dixon, D.G. [Univ. of Waterloo, Ontario (Canada); Power, M. [Univ. of Manitoba, Winnipeg, Manitoba (Canada); Boerger, H.; MacKinnon, M.D.; Meer, T. Van [Syncrude Canada, Fort McMurray, Alberta (Canada)

1995-12-31

258

Numerical and analytical modeling of sanding onset prediction  

E-print Network

cavity (e.g. borehole, perforation tunnel) and applying appropriate sand production criterion to predict the fluid pressure or pressure gradient at which sand production occurs. In this work, we present numerical and analytical poroelastoplastic stress...

Yi, Xianjie

2004-09-30

259

Process of microbial extraction of hydrocarbons from oil sands  

SciTech Connect

A process is described for the separation of hydrocarbon residues from oil and tar sands by microbiological activity. Hydrocarbon residues are released from the sands by contacting with a suspension of oxidase-synthesizing, hydrocarbonmetabolizing microorganisms.

Rabinovitch, I.; Worne, H.E.

1982-09-14

260

Building Whales in Sand and Mind.  

ERIC Educational Resources Information Center

Describes two-week summer workshops on evolution, adaptation, and behavior of whales, conducted for children by Cold Spring Harbor Whaling Museum (New York), and culminating in creation of life-size sand sculptures of whales. Provides selected list of periodicals, teaching materials, identification guides, records, and societies devoted to whales…

Warner, Carolyn

1980-01-01

261

Hydroponic sand culture systems for mycorrhizal research  

Microsoft Academic Search

Summary Tomato plants were inoculated withGlomus fasciculatus mycorrhizal fungi while growing in sand through which recycled nutrient solution was automatically passed several times daily. Concentration of P and N in the solution were maintained at relatively low levels. Roots of inoculated plants became highly infected with mycorrhizal fungi, and yield parameters were significantly increased with inoculation over uninoculated control plants.

J. C. Ojala; W. M. Jarrell

1980-01-01

262

Anelasticity and dispersion in dry unconsolidated sands  

Microsoft Academic Search

Laboratory measurements reveal frame modulus dispersion and creeping behavior in room-dry samples of unconsolidated, quartzo-feldspathic Upper Miocene turbidites from the Wilmington Field, CA. A single standard linear solid model predicts both the dispersion and the creep response. Similar behavior is observed in Ottawa sand samples when mixed with wetted Montmorillonite. In this case the magnitude of dispersion and creep increase

Carl Chang; Daniel Moos; Mark D. Zoback

1997-01-01

263

SANDIA REPORT SAND98-2668  

E-print Network

. Veers Prepared by Sandia National Laboratories Albuqtmrque, New Mexico 87185 and Livermore, California and Manufacturing Software Paul S. Veers Wind Energy Technology Sandia National Laboratories P.O. BOX 5800SANDIA REPORT SAND98-2668 Unlimited Release Reprinted December 1998 G. Richard Eisler, Paul S

264

SOURCE ASSESSMENT: TRANSPORT OF SAND AND GRAVEL  

EPA Science Inventory

This report describes a study of atmospheric emissions from the transport of sand and gravel on unpaved roads. The potential environmental effect of this emission source was evaluated using source severity, defined as the ratio of the time-averaged maximum ground level concentrat...

265

Shifting Sands on Mars: 3 Case Studies  

NASA Astrophysics Data System (ADS)

Repeated HiRISE observations show evidence for sand movement in intracrater dune deposits in the martian tropics, as well as in the north polar erg. These observations suggest that martian dunes are presently active, and not fossil relics of an earlier climatic epoch.

Geissler, P. E.; Stantzos, N. W.; Bridges, N. T.; HiRISE Science Team

2011-03-01

266

Canadian Oil Sands: Canada's Energy Advantage  

E-print Network

crude oil production, global energy demand, the estimated reserves and resources at Syncrude, viewsCanadian Oil Sands: Canada's Energy Advantage 0 #12;Forward looking information 1 In the interest as to the amount of "reserves" remaining globally, the future of Canadian oil and energy supply, the view

Boisvert, Jeff

267

Canadian Oil Sands: Canada An Emerging Energy  

E-print Network

(collectively "statements") with respect to: expectations regarding crude oil production, global energy demand1 Canadian Oil Sands: Canada ­ An Emerging Energy Superpower 0 University of Alberta February 8, the future of Canadian oil and energy supply, the view that the world will need oil for decades to come

Boisvert, Jeff

268

TOXOPLASMOSIS IN SAND FOX (VULPUS RUEPPELLII)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fatal toxoplasmosis was diagnosed in a sand fox (Vulpes rueppelli) from United Arab Emirates. Toxoplasma gondii-like tachyzoites were found associated with necrosis in intestine, spleen, liver, pancreas, lungs, mesenteric lymph nodes, and the heart. Ttachyzoites reacted positively with T. gondii-spe...

269

Andreas Sand Thomas Mailund Christian N. S.  

E-print Network

important problem in molecular docking is to identify low energy binding modes of proteins and a ligands have to be docked against a protein which is time consuming unless expensive computer clusters are used in Bioinformatics ! ! Martin Simonsen1,2, Andreas Sand1,2, Thomas Mailund1 and Christian N.S. Pedersen1,2 ! ! 1

Schierup, Mikkel Heide

270

EXPRESSING SUPPLY LIMITATION IN SAND SALTATION  

EPA Science Inventory

Saltation-driven sandblasting is the most effective producer of windblown dust. Modeling of wind-blown dust emissions requires an efficient parameterization of sand flux in the saltating mode. According to the theory of P. R. Owen the horizontal mass flux of saltating uniform p...

271

22. INTERIOR VIEW WITH INTERIOR VIEW OF MOLDING SANDS CONTROL ...  

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

22. INTERIOR VIEW WITH INTERIOR VIEW OF MOLDING SANDS CONTROL AND TEST LAB FOR UNIT NO. 2 GREY IRON DISAMATIC. SAND CASTING TECHNICIAN, ROY BATES, TESTS THE WEIGHT OF THE SAND, DRYS IT, AND WEIGHT IT AGAINST STANDARDS TO CALCULATE THE CORRECT MOISTURE NEEDED FOR DIFFERENT MOLDS. THE SAND MIX VARY WITH THE SIZE AND COMPOSITION OF THE CASTING. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

272

Geology Fieldnotes: White Sands National Monument, New Mexico  

NSDL National Science Digital Library

The White Sands National Monument site contains park geology information, maps, related links, and visitor information. The park geology section discusses the park's geologic history, the formation of the gypsum sand dunes, and the four types of dunes found at the White Sands National Monument: dome, barchan, transverse, and parabolic. The park maps section includes a map of the White Sands National Monument and the surrounding area, showing the location of each type of dune.

273

Imaging of Acoustic Waves in Sand  

SciTech Connect

There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.

Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall

2003-08-01

274

Drag reduction using superhydrophobic sanded Teflon surfaces  

NASA Astrophysics Data System (ADS)

In this paper, a series of experiments are presented which demonstrate drag reduction for the laminar flow of water through microchannels using superhydrophobic surfaces with random surface microstructure. These superhydrophobic surfaces were fabricated with a simple, inexpensive technique of sanding polytetrafluoroethylene (PTFE) with sandpaper having grit sizes between 120- and 600-grit. A microfluidic device was used to measure the pressure drop as a function of the flow rate to determine the drag reduction and slip length of each surface. A maximum pressure drop reduction of 27 % and a maximum apparent slip length of b = 20 ?m were obtained for the superhydrophobic surfaces created by sanding PTFE with a 240-grit sandpaper. The pressure drop reduction and slip length were found to increase with increasing mean particle size of the sandpaper up to 240-grit. Beyond that grit size, increasing the pitch of the surface roughness was found to cause the interface to transition from the Cassie-Baxter state to the Wenzel state. This transition was observed both as an increase in the contact angle hysteresis and simultaneously as a reduction in the pressure drop reduction. For these randomly rough surfaces, a correlation between the slip length and the contact angle hysteresis was found. The surfaces with the smallest contact angle hysteresis were found to also have the largest slip length. Finally, a number of sanding protocols were tested by sanding preferentially along the flow direction, across the flow direction and with a random circular pattern. In all cases, sanding in the flow direction was found to produce the largest pressure drop reduction.

Song, Dong; Daniello, Robert J.; Rothstein, Jonathan P.

2014-08-01

275

Well completion process for formations with unconsolidated sands  

DOEpatents

A method for consolidating sand around a well, involving injecting hot water or steam through well casing perforations in to create a cement-like area around the perforation of sufficient rigidity to prevent sand from flowing into and obstructing the well. The cement area has several wormholes that provide fluid passageways between the well and the formation, while still inhibiting sand inflow.

Davies, David K. (Kingwood, TX); Mondragon, III, Julius J. (Redondo Beach, CA); Hara, Philip Scott (Monterey Park, CA)

2003-04-29

276

BEHAVIOR OF A SAND RIDGE MODEL Juan Mario Restrepo  

E-print Network

BEHAVIOR OF A SAND RIDGE MODEL Juan Mario Restrepo Mathematics Department University of California, Los Angeles Los Angeles, CA 90095 Abstract. A model for the formation and evolution of longshore sand waves, which are represented by wave packets, and a sandy bottom topography, conspire to produce sand

Soatto, Stefano

277

Numerical simulation of wind sand movement in straw checkerboard barriers.  

PubMed

Straw checkerboard barrier (SCB) is the most representative antidesertification measure and plays a significant role in antidesertification projects. Large-eddy simulation and discrete-particle tracing were used to numerically simulate the wind sand movement inside the straw checkerboard barrier (SCB), study the movement characteristics of sand particles, find the transverse velocities of sand particles and flow field, and obtain the contour of the transverse velocity of coupled wind field within the SCB. The results showed that 1) compared with that at the inlet of the SCB, the sand transport rate inside the SCB greatly decreases and the speed of sand grain movement also evidently drops, indicating that the SCB has very good sand movement preventing and fixing function; 2) within the SCB there exists a series of unevenly distributed eddies of wind sand flow, their strength decreases gradually with increasing the transverse distance; 3) affected by eddies or reflux, sand particles carried by the wind sand flow have to drop forward and backward the two interior walls inside the SCB, respectively, forming a v-shaped sand trough; 4) the sand transport rate gradually decreases with increasing number of SCBs, which reveals that the capacity of the wind field to transport sand particles decreases. This research is of significance in sandstorm and land desertification control. PMID:24026396

Huang, Ning; Xia, Xianpan; Tong, Ding

2013-09-01

278

Tar sands program FY80. Annual report, October 1980  

Microsoft Academic Search

Sandia National Laboratories has the responsibility for assisting the Laramie Energy Technology Center's Tar Sands Program in the areas of reservoir access and alternate extraction concepts. Activities in the first area have concentrated on high-temperature packers, insulated injection string installation, steam quality measurements, sand control, and controlled-source audio magnetotelluric surveying. Also, a tar sands permeability enhancement workshop was held, and

J. R. Wayland; A. J. Mulac; R. L. Fox; L. C. Bartel

1981-01-01

279

Plant Availability of Metals in Waste Foundry Sands  

Technology Transfer Automated Retrieval System (TEKTRAN)

Foundries in the United States generate several million tons of waste sand each year. These sands are no longer suitable for metalcasting processes, and about 90% are discarded in landfills. However, the majority of these waste foundry sands (WFSs) qualify as non-hazardous industrial waste and the...

280

Design and management of conventional fluidized-sand biofilters  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fluidized sand biofilters (FSBs) are relatively compact, efficient, and cost-competitive biofilters, especially in recirculating systems that require maintaining consistently low levels of ammonia and nitrite. Filter sand is low cost (often $70-200/m3 of sand delivered) and has a high specific surf...

281

Supercritical-Fluid Extraction of Oil From Tar Sands  

NASA Technical Reports Server (NTRS)

New supercritical solvent mixtures have been laboratory-tested for extraction of oil from tar sands. Mixture is circulated through sand at high pressure and at a temperature above critical point, dissolving organic matter into the compressed gas. Extract is recovered from sand residues. Low-temperature super-critical solvents reduce energy consumption and waste-disposal problems.

Compton, L. E.

1982-01-01

282

Spring 1986 Research Could Help Revegetate Sand Hills  

E-print Network

in the Sand Hills, " said Michael G. Boo salis , UNL plant pathologist. He expl ained that this fungi formed ause they do not have host plants to SUpp0l1 their growth and repro- duction . "This results in bare to the Sand Hills were com pleted , and we foun d that growth of sand bluestem , little bluestern, prairie

Nebraska-Lincoln, University of

283

On the size distribution of sand Michael Srensen  

E-print Network

On the size distribution of sand Michael Sørensen Department of Applied Mathematics and Statistics is presented of the development of the size distribution of sand while it is transported from a source in unimodal grain size distributions in natural sand deposits, as pointed out by Bagnold. It implies

Sørensen, Michael

284

Metabolism of BTEX and naphtha compounds to methane in oil sands tailings.  

PubMed

Naphtha, comprising low molecular weight aliphatics and aromatics (C3-C14), is used as a diluent in processing of bitumen from oil sands. A small fraction (<1%) is lost to tailings waste and incorporated into mature fine tailings (MFT). BTEX (benzene, toluene, ethylbenzene, and xylenes) and whole naphtha were assessed for biodegradation under methanogenic conditions using MFT from an oil sands tailings settling basin. MFT spiked with 0.05-0.1% w/v of BTEX compounds produced up to 2.1 (+/-0.1) mmol of methane during 36 weeks of incubation. Metabolism of 0.5-1.0% w/v naphtha in MFT yielded up to 5.7 (+/-0.2) mmol of methane during 46 weeks of incubation. Gas chromatographic analyses showed that BTEX degraded in the sequence: toluene > o-xylene > m- plus p-xylene > ethylbenzene > benzene. Only 15-23% of whole naphtha, mainly n-alkanes (in the sequence: nonane > octane > heptane) and some BTEX compounds (toluene > o-xylene > m-xylene), was metabolized. Other naphtha constituents, such as iso-paraffins and naphthenes, remained unchanged during this period. These results suggest that the microbial communities in the MFT can readily utilize certain fractions of unrecovered naphtha in oil sands tailings and support methanogenesis in settling basins. Current study findings could influence extraction process, MFT management, and reclamation options. PMID:17438786

Siddique, Tariq; Fedorak, Phillip M; MacKinnon, Michael D; Foght, Julia M

2007-04-01

285

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

286

A laboratory investigation of vibratory compaction of dry soils  

E-print Network

Compsctaon Equipment Crawler-type tractor, Rubber-tired roller, Steel-wheel roller, Vxbrstory compactors Dry Unxt Height ~/ 125- 140 GRAVEL GP Poorly graded gravels or gravel- sand mixtures, little or no fines Same as GW 110-140 AND GRAVELLY SOILS... GM(d) Silt y gravs la, mixturos gravel-sand-silt Rubber-t Sheepsfo (Close c morsture ired roller, ot roller ontrol oF 125 ? 14 5 GM(u) Silty gravels, mixtures gravel-sand-silt Sheepsfoot roller, Rubber-tired roller 115 ? 13 5 SAND...

Webster, Cecil Ray

1984-01-01

287

Porosity and packing of Holocene river, dune, and beach sands  

SciTech Connect

The porosity and packing of 174 samples of well-sorted surficial and shallowly buried (to 17 m), unconsolidated Holocene sands were determined by point counting the upper surface of thin sections of epoxy-impregnated samples in reflected light. Average depositional porosity for 124 surficial beach sands, river point-bar and braid-bar sands, and eolian dune sands is between 40% and 58%. Beach sands exhibit an average packing value (contact index = CI) of 0.79, river sands an average IC of 0.91, and eolian dune sands an average CI of 1.02. Packing gets tighter with depth, but the authors found no decrease in porosity with depth for river and beach sands buried to 17 m. Thus, packing is more sensitive to small changes in fabric than is porosity. Beach sands typically contain 5.5% oversized pores (OSP), river sands 3.8% OSP, and eolian dune sands 4.0% OSP. Most OSP are packing defects rather than dissolution pores, although trapped air bubbles are common in some beach sands. OSP decrease linearly with depth to 17 m, our deepest sample. Extrapolation of our data indicates that they will be destroyed at a depth less than 100 m. Significant differences in porosity, oversized-pore, and packing values exist between most point-bar and braid-bar deposits and between two heavily sampled point bars, but no significant differences in these values exist when braid-bar sands are compared to other braid-bar sands. Sands form different beaches have significant differences in porosity, oversized pores, and packing. The average porosity is 46% for eolian ripple strata, 50% for grain-fall strata, and 51% for grain-flow strata. Ripple strata are tighter packed than grain-fall and grain-flow strata.

Atkins, J.E. (Conoco, Inc., Oklahoma City, OK (United States)); McBride, E.F. (Univ. of Texas, Austin (United States))

1991-03-01

288

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

289

Interaction of oil sands tailings particles with polymers and microbial cells: First steps toward reclamation to soil.  

PubMed

Production of bitumen by surface mining of Alberta's oil sands has given rise to tailings ponds, containing large volumes of finely dispersed clays (10(8) m(3) ), which settle only slowly. The mature fine tailings (MFT) in these ponds are operationally defined as consisting of particles smaller than 44 ?m with a solids content in excess of 30% (w/w). Increasing the rate of densification of MFT is a rate-limiting step in tailings pond reclamation. Accelerated densification has been achieved through mixing of MFT with sand in the presence of calcium sulfate as a binding agent to generate consolidated tailings. Addition of negatively charged polymer, together with either calcium or magnesium ions, is similarly effective. Although toxic to higher aquatic life, tailings ponds harbour a wide variety of mainly anaerobic microbes. These convert residual hydrocarbon, causing methane emissions of up to 10(4) m(3) day(-1) . Interestingly, anaerobic microbial activity also accelerates tailings pond densification. Hence, many technologies designed to accelerate densification move tailings, at least conceptually, towards soil in which sand and clay particles are linked by large amounts of humic and fulvic acid polymers supporting large numbers of microbes in a mechanically stable structure. © 2012 Wiley Periodicals, Inc. Biopolymers 99: 257-262, 2013. PMID:23348673

Voordouw, Gerrit

2013-04-01

290

Fine Arts in the Curriculum.  

ERIC Educational Resources Information Center

In this anthology the issues related to the fine arts (music, theater, visual arts) in the elementary secondary curriculum are examined. The fifteen articles, ranging in length from one to seven pages, are followed by a biographical page briefly identifying the contributors. The articles are: "What's It All About?" (Frederick B. Tuttle, Jr.);…

Tuttle, Frederick B., Jr., Ed.

291

Fine Particle Scrubbing: A Proceedings  

ERIC Educational Resources Information Center

These articles deal with the proceedings of a 1974 symposium on the use of wet scrubbers for the control of fine particle air pollutants. Various wet scrubbers, their engineering, performance, efficiency, and future are discussed. Tables, formulas, and models are included. (TK)

Journal of the Air Pollution Control Association, 1974

1974-01-01

292

Brane Inflation and Fine Tuning  

E-print Network

We argue about the importance of embedding the successful mechanism of Inflation in the context of a fundamental theory. We review some of the attempts in this direction made in the framework of String Theory. In particular we report on recent developments in Brane Inflation with emphasis on the fine tuning issue.

Enrico Pajer

2007-09-14

293

Analysis of Wind-blown Sand Movement over Transverse Dunes  

NASA Astrophysics Data System (ADS)

Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand particle saltation. In this paper, we propose a numerical model for the coupling effect between wind flow and saltating sand particles to simulate wind-blown sand movement over the slope surface and use the SIMPLE algorithm to calculate wind flow and simulate sands transport by tracking sand particle trajectories. We furthermore compare the result of numerical simulation with wind tunnel experiments. These results prove that sand particles have obvious effect on wind flow, especially that over the leeward slope. This study is a preliminary study on windblown sand movement in a complex terrain, and is of significance in the control of dust storms and land desertification.

Jiang, Hong; Huang, Ning; Zhu, Yuanjian

2014-12-01

294

Analysis of Wind-blown Sand Movement over Transverse Dunes  

PubMed Central

Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand particle saltation. In this paper, we propose a numerical model for the coupling effect between wind flow and saltating sand particles to simulate wind-blown sand movement over the slope surface and use the SIMPLE algorithm to calculate wind flow and simulate sands transport by tracking sand particle trajectories. We furthermore compare the result of numerical simulation with wind tunnel experiments. These results prove that sand particles have obvious effect on wind flow, especially that over the leeward slope. This study is a preliminary study on windblown sand movement in a complex terrain, and is of significance in the control of dust storms and land desertification. PMID:25434372

Jiang, Hong; Huang, Ning; Zhu, Yuanjian

2014-01-01

295

A contribution of laser altimetry images to the geomorphology of the Late Holocene inland drift sands of the European Sand Belt  

Microsoft Academic Search

The paper explores the possibilities of applying the analysis of laser altimetry images to Dutch drift sands. All along the European Sand Belt, which stretches from Great Britain to the Ural Mountains, Late Glacial cover sands, river dunes and other ice–age deposits were reactivated as drift sand during the Holocene. New insights were obtained in three aspects of drift–sands geomorphology.

P. D. Jungerius; M. J. P. M. Riksen

2010-01-01

296

Strength and sintering effects at ejection of explosively driven sand  

NASA Astrophysics Data System (ADS)

A description of the response of sand to extreme loads is very important for the evaluation of the sand ejecta impact effects on various targets. Sand is a complex material to simulate because of its porosity where the inter-phase equilibrium is hard to achieve under transient shock wave loading. A previously developed two-phase model with strength has been implemented in CTH and applied to sand. The shock response of the sand, including the Hugoniot abnormality known from the literature for highly porous silica, is adequately described with the material model. The sand unloading effects appearing as the ejecta are observed in the present work using dynamic flash X-ray of an aluminium target plate loaded by limestone sand ejecta from the detonation of a buried high explosive charge. The CTH modelling results compared with the flash X-ray images have demonstrated good agreement, particularly, in the description of momentum transfer to the target.

Resnyansky, A. D.; Weckert, S. A.

2014-05-01

297

Stream sediment decomposition in contrasting glacial sand, peat and muck reaches of a wetland stream  

NASA Astrophysics Data System (ADS)

Low-gradient peatland streams often have unconventional channel forms which are hypothesized to be driven by variability in groundwater discharge and organic matter production and decomposition. These aquatic systems are also regionally important sources of CO2 and CH4, and knowledge of spatial controls of decomposition could help constrain the regional carbon budget. We investigated how sediment texture, organic matter content, and groundwater exchange affect the metabolism of stream sediments in a wetland stream in northern Wisconsin, U.S. We compared an organic-rich wetland reach with adjacent glacial sand reaches and also identified six cross-sections in the wetland where fine, unconsolidated organic sediments (muck) were positioned adjacent to a solid peat bed. Based on sediment temperature anomalies and substantial previous work on groundwater hydrology, we found that loose organic sediments were always associated with groundwater upwelling, which was not seen in the adjacent peat. Sediments from sand and muck cores were incubated aerobically, and at each wetland cross-section we incubated cores under both aerobic and anaerobic conditions. Aerobic respiration rates in muck sediments were higher than for glacial sands, and there were substantial localized differences in the wetland sediments associated with groundwater upwelling. We found that aerobic and anaerobic respiration were higher in muck sediments than in peat (nearly threefold, p<0.05) which confirms that decomposition is more rapid in sediments receiving constant groundwater discharge. Sediment organic matter was lower in muck compared to solid peat sediments, but much higher than in sand. The resulting variation in sediment bioavailability and quantity support the hypothesis that biological processes, rather than purely physical processes, dictate the unique cross-sectional and planform geometry of peatland stream channels. Further, these patterns can be used to explain previously documented reach and regional scale variability in stream greenhouse gas emissions.

Spawn, S.; Crawford, J. T.; Stanley, E. H.

2013-12-01

298

Stratified chaos in a sand pile formation  

E-print Network

Sand pile formation is often used to describe stratified chaos in dynamic systems due to self-emergent and scale invariant behaviour. Cellular automata (Bak-Tang-Wiesenfeld model) are often used to describe chaotic behaviour, as simulating physical interactions between individual particles is computationally demanding. In this study, we use a state-of-the-art parallel implementation of the discrete element method on the graphical processing unit to simulate sand pile formation. Interactions between individual grains were simulated using a contact model in an Euler integration scheme. Results show non-linear self-emergent behaviour which is in good agreement with experimental results, theoretical work and self organized criticality (SOC) approaches. Moreover, it was found that the fully deterministic model, where the position and forces on every individual particle can be determined every iteration has a brown noise signal in the x and y direction, where the signal is the z direction is closer to a white noise spectrum.

Ate Poortinga; Jan G. Wesseling; Coen J. Ritsema

2014-03-04

299

Three dimensional fabric evolution of sheared sand  

SciTech Connect

Granular particles undergo translation and rolling when they are sheared. This paper presents a three-dimensional (3D) experimental assessment of fabric evolution of sheared sand at the particle level. F-75 Ottawa sand specimen was tested under an axisymmetric triaxial loading condition. It measured 9.5 mm in diameter and 20 mm in height. The quantitative evaluation was conducted by analyzing 3D high-resolution x-ray synchrotron micro-tomography images of the specimen at eight axial strain levels. The analyses included visualization of particle translation and rotation, and quantification of fabric orientation as shearing continued. Representative individual particles were successfully tracked and visualized to assess the mode of interaction between them. This paper discusses fabric evolution and compares the evolution of particles within and outside the shear band as shearing continues. Changes in particle orientation distributions are presented using fabric histograms and fabric tensor.

Hasan, Alsidqi; Alshibli, Khalid (UWA)

2012-10-24

300

Scaling laws in aeolian sand transport  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

301

Space Radar Image of Namibia Sand Dunes  

NASA Technical Reports Server (NTRS)

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

1994-01-01

302

Comparison of SAND-II and FERRET  

SciTech Connect

A comparison was made of the advantages and disadvantages of two codes, SAND-II and FERRET, for determining the neutron flux spectrum and uncertainty from experimental dosimeter measurements as anticipated in the FFTF Reactor Characterization Program. This comparison involved an examination of the methodology and the operational performance of each code. The merits of each code were identified with respect to theoretical basis, directness of method, solution uniqueness, subjective influences, and sensitivity to various input parameters.

Wootan, D.W.; Schmittroth, F.

1981-01-01

303

Fusion of arkosic sand by intrusive andesite  

USGS Publications Warehouse

An andesite dike in the Valles Mountains of northern New Mexico has intruded and partly fused arkosic sediments for a distance of 50 feet from its contacts. The dike is semi-circular in form, has a maximum width of about 100 feet, and is about 500 feet long. Small associated arcuate dikes are arranged in spiral fashion around the main dike, suggesting that they were intruded along shear fractures similar to those described by Burbank (1941). The fused rocks surrounding the andesite dike are of three general types: 1) partly fused arkosic sand, 2) fused clay, and 3) hybrid rocks. The fused arkosic sand consists of relict detrital grains of quartz, orthoclose, and plagioclase, imbedded in colorless glass containing microlites of tridymite, cordierite, and magnetite. The relict quartz grains are corroded and embayed by glass; the orthoclase is sanidinized and partly fused; and the plagioclase is inverted to the high temperature form and is partly fused. The fused clay, which was originally a mixture of montmorillonite and hydromica, consists primarily of cordierite but also contains needle-like crystals of sillimanite (?) or mullite (?). The hybrid rocks originated in part by intermixing of fused arkosic sediments and andesitic liquid and in part by diffusion of mafic constituents through the fused sediments. They are rich in cordierite and magnetite and also contain hypersthene, augite, and plagioclase. The composition of pigeonite in the andesite indicates that the temperature of the andesite at the time of intrusion probably did not exceed 1200?C. Samples of arkosic sand were fused in the presence of water in a Morey bomb at 1050?C. Stability relations of certain minerals in the fused sand suggest that fusion may have taken place at a lower temperature, however, and the fluxing action of volatiles from the andesite are thought to have made this possible.

Bailey, Roy A.

1954-01-01

304

Pullout capacity of batter pile in sand  

PubMed Central

Many offshore structures are subjected to overturning moments due to wind load, wave pressure, and ship impacts. Also most of retaining walls are subjected to horizontal forces and bending moments, these forces are due to earth pressure. For foundations in such structures, usually a combination of vertical and batter piles is used. Little information is available in the literature about estimating the capacity of piles under uplift. In cases where these supporting piles are not vertical, the behavior under axial pullout is not well established. In order to delineate the significant variables affecting the ultimate uplift shaft resistance of batter pile in dry sand, a testing program comprising 62 pullout tests was conducted. The tests are conducted on model steel pile installed in loose, medium, and dense sand to an embedded depth ratio, L/d, vary from 7.5 to 30 and with various batter angles of 0°, 10°, 20°, and 30°. Results indicate that the pullout capacity of a batter pile constructed in dense and/or medium density sand increases with the increase of batter angle attains maximum value and then decreases, the maximum value of P? occurs at batter angle approximately equal to 20°, and it is about 21–31% more than the vertical pile capacity, while the pullout capacity for batter pile that constructed in loose sand decreases with the increase of pile inclination. The results also indicated that the circular pile is more resistant to pullout forces than the square and rectangular pile shape. The rough model piles tested is experienced 18–75% increase in capacity compared with the smooth model piles. The suggested relations for the pullout capacity of batter pile regarding the vertical pile capacity are well predicted.

Nazir, Ashraf; Nasr, Ahmed

2012-01-01

305

Sand transport, erosion and granular electrification  

NASA Astrophysics Data System (ADS)

The transport of granular materials by wind has a major impact on our environment through sand/soil erosion and the generation and transport of atmospheric dust aerosols. Terrestrially the transport of dust involves billions of tons of material every year, influencing the global climate and impacting directly upon human health. Research in aeolian transport involves the inter-related fields of fluid dynamics, granular materials and electrification/electrostatics which are in themselves diverse and complex. This review only touches upon this intricacy, but aims to overview the latest work which is expanding our current understanding and outline the areas of advancement needed in the future. Presentation is made of current models for wind driven detachment/entrainment and the transport rates of sand and dust, including the effects of contact induced grain electrification. This ubiquitous phenomenon can affect grain transport through the generation of intense electric fields and processes of electrostatic assembly. Importantly the transport of sand is characterized by saltation, which is known to be an active process for erosion and therefore a source for dust and sand formation. Using novel erosion simulation techniques the link between grain transport rates and erosion rates has been quantified. Furthermore this can be linked to production rates for dust and has been associated with chemical and mineral alteration through a process of mechanical activation of fractured surfaces. This work has implications for the evolution of all terrestrial-like planetary surfaces. Studies in non-terrestrial environments force researchers to be less empirical, ultimately leading to a deeper understanding of these processes.

Merrison, J. P.

2012-06-01

306

Guide to preparing SAND reports. Revised  

SciTech Connect

This guide contains basic information needed to produce a SAND report. Its guidelines reflect DOE regulation and Sandia policy. The guide includes basic writing instructions in an annotated sample report; guidance for organization, format, and layout of reports produced by line organizations; and information about conference papers, journal articles, and brochures. The appendixes contain sections on Sandia`s preferred usage, equations, references, copyrights and permissions, and publishing terms.

Locke, T.K. [ed.

1996-04-01

307

Summertime View of North Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

10 October 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of dunes in one of the several north polar dune fields. The bright surfaces adjacent to some of the dunes are patches of frost. These dunes spend much of the autumn, winter, and spring seasons covered with carbon dioxide frost. Only in late spring and in summer are the dark windblown sands fully exposed.

Over the course of the 9+ years of the MGS mission, the MOC team has sought evidence that sand dunes may be migrating downwind over time. However, no clear examples of the movement of a whole dune have been identified. On Earth, such movement is typically detectable in air photos of the smallest active dunes over periods of a few years. Owing to the fact that the north polar dunes spend much of each martian year under a cover of frost, perhaps these move much more slowly than their frost-free, terrestrial counterparts. The sand may also be somewhat cemented by ice or minerals, likewise preventing vigorous dune migration in the present environment.

This view covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left. The dunes are located near 79.8oN, 127.1oW, and the picture was acquired on 11 September 2006.

2006-01-01

308

Use of recycled fine aggregate in concretes with durable requirements.  

PubMed

The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. PMID:21775123

Zega, Claudio Javier; Di Maio, Angel Antonio

2011-11-01

309

Mars Hand Lens Imager (MAHLI) Efforts and Observations at the Rocknest Eolian Sand Shadow in Curiosity's Gale Crater Field Site  

NASA Technical Reports Server (NTRS)

The Mars Science Laboratory (MSL) mission is focused on assessing the past or present habitability of Mars, through interrogation of environment and environmental records at the Curiosity rover field site in Gale crater. The MSL team has two methods available to collect, process and deliver samples to onboard analytical laboratories, the Chemistry and Mineralogy instrument (CheMin) and the Sample Analysis at Mars (SAM) instrument suite. One approach obtains samples by drilling into a rock, the other uses a scoop to collect loose regolith fines. Scooping was planned to be first method performed on Mars because materials could be readily scooped multiple times and used to remove any remaining, minute terrestrial contaminants from the sample processing system, the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA). Because of this cleaning effort, the ideal first material to be scooped would consist of fine to very fine sand, like the interior of the Serpent Dune studied by the Mars Exploration Rover (MER) Spirit team in 2004 [1]. The MSL team selected a linear eolian deposit in the lee of a group of cobbles they named Rocknest (Fig. 1) as likely to be similar to Serpent Dune. Following the definitions in Chapter 13 of Bagnold [2], the deposit is termed a sand shadow. The scooping campaign occurred over approximately 6 weeks in October and November 2012. To support these activities, the Mars Hand Lens Imager (MAHLI) acquired images for engineering support/assessment and scientific inquiry.

Edgett, K. S.; Yingst, R. A.; Minitti, M. E.; Goetz, W.; Kah, L. C.; Kennedy, M. R.; Lipkaman, L. J.; Jensen, E. H.; Anderson, R. C.; Beegle, L. W.; Carsten, J. L.; Cooper, B.; Deen, R. G.; Dromart, G.; Eigenbrode, J. L.; Grotzinger, J. P.; Gupta, S.; Hamilton, V. E.; Hardgrove, C. J.; Harker, D. E.; Herkenhoff, K. E.; Herrera, P. N.; Hurowitz, J. A.; Jandura, L.; Ming, D. W.

2013-01-01

310

Eolian cover sands: a sedimentologic model and paleoenvironmental implications  

SciTech Connect

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

Lea, P.D.

1985-01-01

311

Spatial Variability in Magnetic Properties of Sands on Cedar Beach, Western Lake Erie, Ontario, Canada  

NASA Astrophysics Data System (ADS)

Variations in magnetic properties can be used to monitor sand movement on beaches and shorelines. To investigate spatial variation in magnetic properties of sands on Cedar Beach, western Lake Erie, Ontario, Canada, we conducted surficial magnetic susceptibility measurements, sieve analyses, mass-normalized susceptibility analysis, Curie-point determinations, saturation isothermal remanent magnetization (SIRM) acquisition, S-ratio and hysteresis measurements for a set of samples. Three representative cross-shore transects (West, Middle and East) were chosen to investigate variations in concentration and grain size of magnetic components, and distribution of physical grain sizes. The cross-shore beach was divided into three zones (Zone 1, 2 and 3) to represent a lower lakeward region close to the water line, the upper swash zone and the landward region beyond the upper swash zone, respectively. The West transect shows the highest magnetic concentration and finest physical particle size, in contrast with the East showing the lowest magnetic concentration and coarsest size, and lower magnetic concentration and coarser physical sizes were observed for the Middle. The fine fractions (<180um) most contribute to magnetic concentration parameters. Zone 1 usually shows much lower magnetic concentration and contains much coarser sand particles than Zone 2 and 3. Sieve analysis generally suggests Zone 1, 2 and 3 are dominated by sand fractions of >300um, <250um and 180-500um, respectively. Finer fractions (<250um) most contribute to the magnetic concentration, showing the highest mass-normalized susceptibility (46.3kg-1) in the West transect. High temperature susceptibility curves are reversible in argon, showing Curie points (Tc) close to 580°C, suggesting magnetite is the dominant magnetic mineral. The Hopkinson-type peaks were observed between 500°C and 580°C for some samples in Zone 1, which can be explained by change in domain state or domain wall or creation of a new magnetic phase. Most step IRM acquisition spectra show 95% of the magnetization gained below 200 mT, and S-300 ratios are close to one, indicating the presence of fully saturated, coarse and fine magnetite. S-60 and S-100 ratios show high values in Zone 2 and 3, while a drop in values occurs in Zone 1, suggesting sands in Zone 1 contain more higher coercivity minerals (hematite or maghemite) than in Zone 2 and 3. IRM magnetic component analyses suggest that some larger fractions (>250um) contain a mixture of lower coercivity and higher coercivity minerals. This is consistent with Zone 1 with sand fractions (>300um) has a higher probability of being wet and affected by oxidation than Zone 2 and 3 that have a higher probability of being dry. From east to west, different grain-size fractions in the East profile generally reveal higher coercivity values than in the West and Middle, indicating the coarser fractions contain more high coercivity minerals than the finer sand fractions. All samples generally fall into the PSD to MD field on a Day diagram. This study is potential to identify transport paths of beach sediments and monitor shoreline changes.

Zhang, S.; Cioppa, M. T.; Zhang, S.

2009-12-01

312

Choice of fineness of pulverized coal  

SciTech Connect

Various methods for choosing the fineness of power plant coal dust are reviewed and analytical expressions for determining the fineness are presented. It is shown that the use of the yield of combustibles as a parameter is not always suitable for evaluating the fineness of pulverized coal. The suggested expression for computing the fineness bears composite parameters that allow for the heat value of the volatiles and for the internal surface of the fuel particles.

E.N. Tolchinskii; A.Yu. Lavrent'ev [All-Russian Thermal Engineering Institute (VTI), Moscow (Russian Federation)

2002-11-15

313

Two Proofs of Fine's Theorem  

E-print Network

Fine's theorem concerns the question of determining the conditions under which a certain set of probabilities for pairs of four bivalent quantities may be taken to be the marginals of an underlying probability distribution. The eight CHSH inequalities are well-known to be necessary conditions, but Fine's theorem is the striking result that they are also a sufficient condition. It has application to the question of finding a local hidden variables theory for measurements of pairs of spins for a system in an EPRB state. Here we present two simple and self-contained proofs of Fine's theorem in which the origins of this non-obvious result can be easily seen. The first is a physically motivated proof which simply notes that this matching problem is solved using a local hidden variables model given by Peres. The second is a straightforward algebraic proof which uses a representation of the probabilities in terms of correlation functions and takes advantage of certain simplifications naturally arising in that representation. A third, unsuccessful attempt at a proof, involving the maximum entropy technique is also briefly described

J. J. Halliwell

2014-03-27

314

Observations of substorm fine structure  

NASA Astrophysics Data System (ADS)

Particle and magnetic field measurements on the CRRES satellite were used, together with geosynchronous satellites and ground-based observations, to investigate the fine structure of a magnetospheric substorm on February 9, 1991. Using the variations in the electron fluxes, the substorm activity was divided into several intensifications lasting about 3-15 minutes each. The two main features of the data were: (1) the intensifications showed internal fine structure in the time scale of about 2 minutes or less. We call these shorter periods activations. Energetic electrons and protons at the closest geosynchronous spacecraft (1990 095) were found to have comparable activation structure. (2) The energetic (>69 keV) proton injections were delayed with respect to electron injections, and actually coincided in time with the end of the intensifications and partial returns to locally more stretched field line configuration. We propose that the energetic protons could be able to control the dynamics of the system locally be quenching the ongoing intensification and possibly preparing the final large-scale poleward movement of the activity. It was also shown that these protons originated from the same intensification as the preceeding electrons. Therefore, the substorm instability responsible for the intensifications could introduce a negative feedback loop into the system, creating the observed fine structure with the intensification time scales.

Lazutin, L. L.; Rasinkangas, R.; Kozelova, T. V.; Korth, A.; Singer, H.; Reeves, G.; Riedler, W.; Torkar, K.; Gvozdevsky, B. B.

1998-07-01

315

Impact on demersal fish of a large-scale and deep sand extraction site with ecosystem-based landscaped sandbars  

NASA Astrophysics Data System (ADS)

For the seaward harbour extension of the Port of Rotterdam in the Netherlands, approximately 220 million m3 sand was extracted between 2009 and 2013. In order to decrease the surface area of direct impact, the authorities permitted deep sand extraction, down to 20 m below the seabed. Biological and physical impacts of large-scale and deep sand extraction are still being investigated and largely unknown. For this reason, we investigated the colonization of demersal fish in a deep sand extraction site. Two sandbars were artificially created by selective dredging, copying naturally occurring meso-scale bedforms to increase habitat heterogeneity and increasing post-dredging benthic and demersal fish species richness and biomass. Significant differences in demersal fish species assemblages in the sand extraction site were associated with variables such as water depth, median grain size, fraction of very fine sand, biomass of white furrow shell (Abra alba) and time after the cessation of sand extraction. Large quantities of undigested crushed white furrow shell fragments were found in all stomachs and intestines of plaice (Pleuronectes platessa), indicating that it is an important prey item. One and two years after cessation, a significant 20-fold increase in demersal fish biomass was observed in deep parts of the extraction site. In the troughs of a landscaped sandbar however, a significant drop in biomass down to reference levels and a significant change in species assemblage was observed two years after cessation. The fish assemblage at the crests of the sandbars differed significantly from the troughs with tub gurnard (Chelidonichthys lucerna) being a Dufrêne-Legendre indicator species of the crests. This is a first indication of the applicability of landscaping techniques to induce heterogeneity of the seabed although it remains difficult to draw a strong conclusion due the lack of replication in the experiment. A new ecological equilibrium is not reached after 2 years since biotic and abiotic variables are still adapting. To understand the final impact of deep and large-scale sand extraction on demersal fish, we recommend monitoring for a longer period, at least for a period of six years or even longer.

de Jong, Maarten F.; Baptist, Martin J.; van Hal, Ralf; de Boois, Ingeborg J.; Lindeboom, Han J.; Hoekstra, Piet

2014-06-01

316

Dunes versus ripples in deep-water, fine-grained sediments  

NASA Astrophysics Data System (ADS)

The Lower Mount Messenger Formation (LMMF) is characterized by fine- to very fine-grained sediments. While the grain size doesn't change much within the formation, the sedimentary structures do. Perhaps the most striking difference between the channels in the upper part of the LMMF and the lobes in the lower part of the LMMF is the abundance of large-scale, climbing-dune cross-stratification in the lobes and of small-scale, climbing-ripple cross-lamination within channels. The sole presence of climbing dunes in fine-grained sandstones in deep-water lobe complex is surprising. Firstly, dunes are characteristic features largely in fluvial environments. Cross-stratification is not a widespread sedimentary structure in deep-water, part of the reason might be the difficulty in recognizing subtle stratification in weathered outcrop. The absence can be also explained by the fact that the flows might be insufficiently deep or there is never sufficient time for dune formation. Secondly, the hydraulics of the cross-stratification requires sand coarser than 0.2 mm (middle fine sand) to form dunes based on flume experiments. The cross-stratification mostly was documented in deep-water in coarse-grained sediments such as pebbles and gravels in southern Chile and in Quebec, medium to granule-grade sands in Oceanographer Canyon, and medium to coarse-grained sands in the Eocene Hecho Group, etc. Nevertheless, the dunes are documented in fine-grained systems such as Brushy Canyon Formation (the authors use "plow-and-fill" term instead of "dunes"). Thirdly, the cross-stratification is generally documented in confined setting such as channels and scours. But this study shows that the cross-stratification can be present in largely unconfined depositional setting of the LMMF. We postulate that the dunes found in the LMMF can be unusually high ripples from the hydrodynamic point of view. Considering the facts that (1) ripples are different from dunes in outcrop by size and the size of ripples can be as high as laminar sublayer, that (2) the sublayer can exist in fine sand even in high sediment transport rate, and that (3) there can be bedforms such as "rogue ripples", transitional between ripples and dunes, which is higher than ripples but are deposited within the laminar sublayer, we conclude that the ripples can grow to sizes similar to dunes in the fine-grained flows. Thus, the dunes we see in the LMMF might be ripples but unusually high. The high-density flows that deposited the sediments in the lower part of the LMMF formed a thicker laminar sublayer, due to higher sediment fallout rate and higher sediment concentration than in low-density flows. The higher ripples were produced by the thicker laminar sublayer. Low-density flows in the upper part of the LMMF had a thinner sublayer that produced conventional ripples.

Masalimova, L.; Lowe, D. R.

2012-12-01

317

Reconstructing the Pore Space of Sand Samples  

NASA Astrophysics Data System (ADS)

The structure of the pore space is essential for flow and transport in soils. Size, shape and connectivity of the pores determine the distribution of air and water, pore water velocity and solute mixing. So, for a complete understanding of transport processes in soils, the pore geometry must be known. Some processes, for example the drainage of water, depend on narrow structures with sizes of a few micrometers. For this reason, a technique to measure 3D pore structures with high resolution is needed. This presentation will describe the image processing steps needed to provide a pore space with the highest possible fidelity to the measured sample. The projection data were acquired using an imaging system based on synchrotron radiation. This technique allows us to map the pore structure in the range of 10 microns. To transform the projection data into pore space volumes, a chain of actions involving back projection, the application of various filters to suppress noise and artifacts, and segmentation is needed. During experiments at the Swiss Light Source (SLS) we scanned sand samples with diameter 5 mm containing sand particles ranging from 100 to 300 microns with a voxel size of 3.5 microns. At the Hamburger Synchrotron Laboratory (HASYLAB) sand samples with diameter 15 mm containing particles ranging from 100 to 900 microns were mapped with a voxel size of 11 microns. In addition to the scanning of completely dry samples, we intend to investigate the water and air distribution for different degrees of water saturation. Comparing these measurements with numerical simulations, we hope to understand the processes of air and water distribution in more detail.

Kaestner, A.; Lehmann, P.; Fluehler, H.; Wyss, P.; Beckmann, F.

2003-12-01

318

Oil shale, tar sands, and related materials  

SciTech Connect

This sixteen-chapter book focuses on the many problems and the new methodology associated with the commercialization of the oil shale and tar sand industry. Topics discussed include: an overview of the Department of Energy's oil shale R, D, and D program; computer simulation of explosive fracture of oil shale; fracturing of oil shale by treatment with liquid sulfur dioxide; chemistry of shale oil cracking; hydrogen sulfide evolution from Colorado oil shale; a possible mechanism of alkene/alkane production in oil shale retorting; oil shale retorting kinetics; kinetics of oil shale char gasification; a comparison of asphaltenes from naturally occurring shale bitumen and retorted shale oils: the influence of temperature on asphaltene structure; beneficiation of Green River oil shale by density methods; beneficiation of Green River oil shale pelletization; shell pellet heat exchange retorting: the SPHER energy-efficient process for retorting oil shale; retorted oil shale disposal research; an investigation into the potential economics of large-scale shale oil production; commercial scale refining of Paraho crude shale oil into military specification fuels; relation between fuel properties and chemical composition; chemical characterization/physical properties of US Navy shale-II fuels; relation between fuel properties and chemical composition: stability of oil shale-derived jet fuel; pyrolysis of shale oil residual fractions; synfuel stability: degradation mechanisms and actual findings; the chemistry of shale oil and its refined products; the reactivity of Cold Lake asphaltenes; influence of thermal processing on the properties of Cold Lake asphaltenes: the effect of distillation; thermal recovery of oil from tar sands by an energy-efficient process; and hydropyrolysis: the potential for primary upgrading of tar sand bitumen.

Stauffer, H.C.

1981-01-01

319

Investigation of sands subjected to dynamic loading  

E-print Network

INVESTIGATION OF SP&NDS SUBJECTED TO DTNAMIC LOADING A Tucsis By Gary N. Reeves Submitted to the Grad ate Coll Ee of the T xas AGM University in partial fulfillment of the requirements for the deEree of MASTER OF SCIPNCE AuBust 19G7 Major... Subject: Civil EnEineering LABORATORY INVESTIGATION OF SANDS SUBJECTED TO DYNAMIC LOADING A Thesis by Gary N. Reeves Approved as to style and content by: Chairman of Committee Head of Department Membe Me er August 1967 ACIINOWLEDGR&J. 'NTS I...

Reeves, Gary Neil

2012-06-07

320

Sedimentary Rock From Sand: Syringe Simulation  

NSDL National Science Digital Library

This activity will allow students to simulate the formation of sedimentary rocks by compressing sand, water, and other materials in a syringe. The products are allowed to dry, and students will investigate how the properties of the samples of sedimentary rocks so formed are dependent on the extent of their compaction and cementation. The activity will help to explain that for most sediments to become rocks the grains need to be squeezed together (compacted) and/or glued together (cemented) and that the extent of the compaction and the strength of the cementation affect the properties of sedimentary rocks.

321

Heating tar sands formations while controlling pressure  

DOEpatents

Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. A pressure in the majority of the section may be maintained below a fracture pressure of the formation. The pressure in the majority of the section may be reduced to a selected pressure after the average temperature reaches a temperature that is above 240.degree. C. and is at or below pyrolysis temperatures of hydrocarbons in the section. At least some hydrocarbon fluids may be produced from the formation.

Stegemeier, George Leo (Houston, TX) [Houston, TX; Beer, Gary Lee (Houston, TX) [Houston, TX; Zhang, Etuan (Houston, TX) [Houston, TX

2010-01-12

322

Heating tar sands formations to visbreaking temperatures  

DOEpatents

Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat may be controlled so that at least a majority of the section reaches an average temperature of between 200.degree. C. and 240.degree. C., which results in visbreaking of at least some hydrocarbons in the section. At least some visbroken hydrocarbon fluids may be produced from the formation.

Karanikas, John Michael (Houston, TX); Colmenares, Tulio Rafael (Houston, TX); Zhang, Etuan (Houston, TX); Marino, Marian (Houston, TX); Roes, Augustinus Wilhelmus Maria (Houston, TX); Ryan, Robert Charles (Houston, TX); Beer, Gary Lee (Houston, TX); Dombrowski, Robert James (Houston, TX); Jaiswal, Namit (Houston, TX)

2009-12-22

323

Aeolian Sand Transport with Collisional Suspension  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

324

Biogenic crust dynamics on sand dunes  

E-print Network

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

Kinast, Shai; Yizhaq, Hezi; Ashkenazy, Yosef

2012-01-01

325

Sand erosion performance of CVD boron carbide coated tungsten carbide  

Microsoft Academic Search

The erosion performance and the interaction between the micro-mechanisms of erosion and the microstructure of a chemical vapour deposited boron carbide coating are presented. Samples were tested using both water–sand slurry and air–sand jet impingements at 90° incidence. Tests used angular quartz sand with a mean diameter between 135 and 235 ?m and jet impingement velocities between 16 and 268

R. J. K Wood; D. W Wheeler; D. C Lejeau; B. G Mellor

1999-01-01

326

Time-Dependent Behaviour and Static Liquefaction Phenomenon of Sand  

Microsoft Academic Search

Recent laboratory and field experiments have confirmed that sand does indeed exhibit time-dependent behaviour. Based on these\\u000a findings, it was considered necessary to revisit some of the published experimental results on the static liquefaction phenomenon\\u000a of loose anisotropic Hostun RF sand. Time-dependency might have had a significant influence on the observed undrained response\\u000a of anisotropic consolidated sand specimens. Specific triaxial

Erdin Ibraim; Herve Di Benedetto; Thiep Doanh

2009-01-01

327

Dynamics of deposited fly-ash and fine grained magnetite in sandy material of different porosity (column experiments)  

NASA Astrophysics Data System (ADS)

Several studies confirm that soil magnetometry can serve as proxy of industrial immisions as well as heavy-metal contamination. The important assumption for magnetic mapping of contaminated soils is that atmospherically deposited particulate matter, including the ferrimagnetic phase, accumulates in the top soil horizons and remains there over long period. Only if this is true, large areas can be reliably mapped using soil magnetometry, and, moreover, this method can be used also for long-term monitoring. However, in soil types such as sandy soils with different porosity or soils with substantial variability of water regime, translocation of the deposited anthropogenic particles may result in biased (underestimated) values of the measured topsoil magnetic susceptibility. From the physical point of view, this process may be considered as colloid transport through porous medium. In our column experiments in laboratory we used three technical sands with different particle sizes (0,63 - 1.25mm, 0,315-0,80mm, 0,10-0,63mm). Sands in cylinders were contaminated on the surface by fly-ashes from coal-burning power plant (mean grain size 10?m) and fine grained Fe3O4 (grain size < 20 ?m). Soil moisture sensors were used to monitor water regime within the sand columns after controlled rain simulation and temperature distribution in sand column was measured as well. Vertical migration of ferrimagnetic particles-tracers presented in the fly-ash was measured by SM 400 Kappameter. By means of magnetic susceptibility distribution we studied two parameters: gradual shift of peak concentration of contaminants (relative to surface layer) and maximum penetration depth. Results indicated that after rain simulation (pulls infiltration of defined water volume) the positions of peak values moved downwards compared to the initial state and gradual decrease of susceptibility peak values were detected in all studied sand formations. Fly-ash migrated more or less freely in coarse sand material. In medium and fine sand the contaminants moved only to the depths of several cm due to the pore-space blocking and water flow decrease. Fine-grained magnetite shows different behavior. Position of peaks value is more or less stable and maximum depth of penetration is only a few cm in all cases. Higher grain size value is probably reason for higher stability of magnetite. Moreover, magnetic interaction between grains increase "effective" grain size value and restricts transport in material with given porosity. This research is supported by the Grant Agency ASCR under grant IAA300120701

Kapicka, Ales; Kodesova, Radka; Petrovsky, Eduard; Grison, Hana

2010-05-01

328

Hand transmitted vibrations caused by orbital hand sanding machines.  

PubMed

The paper reports and analyses results of vibration measurement carried out on orbital hand sanding machines. Vibrations were measured on the front and rear handles of the FESTO LRB-W1 and LRB-T1 orbital hand sanding machines and at two points on the holding handle of the FESTO RTL-F1 hand sanding machine. The measured levels of the weighted vibration accelerations were compared to the daily exposure limits according to ISO 5349, ISO/TC 108/SC4/14 and NF E90-402. Daily exposures for each type of sanding machine were determined according to the same standards. PMID:7575142

Goglia, V; Risovi?, S; Beljo, R

1995-03-01

329

Reuse of waste cutting sand at Lawrence Livermore National Laboratory  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) examined the waste stream from a water jet cutting operation, to evaluate the possible reuse of waste garnet sand. The sand is a cutting agent used to shape a variety of materials, including metals. Nearly 70,000 pounds of waste sand is generated annually by the cutting operation. The Environmental Protection Department evaluated two potential reuses for the spent garnet sand: backfill in utility trenches; and as a concrete constituent. In both applications, garnet waste would replace the sand formerly purchased by LLNL for these purposes. Findings supported the reuse of waste garnet sand in concrete, but disqualified its proposed application as trench backfill. Waste sand stabilized in a concrete matrix appeared to present no metals-leaching hazard; however, unconsolidated sand in trenches could potentially leach metals in concentrations high enough to threaten ground water quality. A technical report submitted to the San Francisco Bay Regional Water Quality Control Board was reviewed and accepted by that body. Reuse of waste garnet cutting sand as a constituent in concrete poured to form walkways and patios at LLNL was approved.

Mathews, S.; Wilson, K. [Lawrence Livermore National Lab., CA (United States)

1998-12-31

330

Numerical modeling of wind-blown sand on Mars.  

PubMed

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

Huang, HaoJie; Bo, TianLi; Zheng, XiaoJing

2014-09-01

331

Bioclogging and Biocementation in Construction of Water Pond in Sand  

NASA Astrophysics Data System (ADS)

Conventionally, compacted bentonite, geosynthetic clay liner or plastic liners are used to seal ponds, channels, and reservoirs in sand. Recently, a new approach to form a low permeability layer of several centimetres thick through the microbially induced calcium carbonate precipitation (MICP) process has been developed (Chu et al., 2012). This method has been adopted to build a laboratory scale water pond model in sand. Calcium solution for bioclogging and biocementation was supplied initially by spaying to form a layer of the clogged sand by precipitation in the pores and then by slow percolation from solution above sand surface, which formed a crust of calcite. This combination of bioclogging and biocementation formed a sand layer of 1 - 3 cm depth with low permeability. The permeability of sand after this treatment was reduced from the order of 10^-4 m/s to 10^-7 m/s when an average 2.1 kg of Ca per m^2 of sand surface was precipitated. The bending strengths of the walls and the base of the model pond were in the range of 90 to 256 kPa. The unconfined compressive strengths obtained from samples from the walls and the base were in the range of 215 to 932 kPa. The graded sand and uniform supply of calcium solution were used for the model pond construction but it was significant spatial three-dimensional heterogeneity of sand bioclogging and biocementation.

Chu, J.; Ivanov, V.; Stabnikov, V.; Li, B.

2012-12-01

332

Reuse of waste cutting sand at Lawrence Livermore National Laboratory  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) examined the waste stream from a water jet cutting operation, to evaluate the possible reuse of waste garnet sand. The sand is a cutting agent used to shape a variety of materials, including metals. Nearly 70,000 pounds of waste sand is generated annually by the cutting operation. The Environmental Protection Department evaluated two potential reuses for the spent garnet sand: backfill in utility trenches; and as a concrete constituent. In both applications, garnet waste would replace the sand formerly purchases by LLNL for these purposes. Findings supported the reuse of waste garnet sand in concrete, but disqualified its proposed application as trench backfill. Waste sand stabilized in ac concrete matrix appeared to present no metals-leaching hazard; however, unconsolidated sand in trenches could potentially leach metals in concentrations high enough to threaten ground water quality. A technical report submitted to the San Francisco Bay Regional Water Quality Control Board was reviewed and accepted by that body. Reuse of waste garnet cutting sand as a constituent in concrete poured to form walkways and patios at LLNL was approved.

Mathews, S., LLNL

1998-02-25

333

Trajectories of saltating sand particles behind a porous fence  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

334

A Biopersistence Study following Exposure to Chrysotile Asbestos Alone or in Combination with Fine Particles  

PubMed Central

In designing a study to evaluate the inhalation biopersistence of a chrysotile asbestos that was used as a component of a joint-compound, a feasibility study was initiated to evaluate the short-term biopersistence of the chrysotile alone and of the chrysotile in combination witht the sanded reformulated joint-compound. Two groups of Wistar rats were exposed to either 7RF3 chrysotile (Group 2) or to 7RF3 chrysotile combined with aerosolized sanded joint-compound (Group 3). In addition, a control group was exposed to flltered-air. The chrysotile used in the Ready Mix joint compound is rapidly removed from the lung. The chrysotile alone exposure group had a clearance half-time of fibers L > 20 ?m of 2.2 days; in the chrysotile plus sanded exposure group the clearance half-time of fibers L > 20 ?m was 2.8 days. However, across all size ranges there was approximately an order of magnitude decrease in the mean number of fibers remaining in the lungs of Group 3 as compared to Group 2 despite similiar aerosol exposures. Histopathological examination showed that the chrysotile exposed lungs had the same appearance as the flltered-air controls. This study uniquely illustrates that additional concurrent exposure to an aerosol of the sanded joint-compound, with large numbers of fine-particles depositing in the lungs, accelerates the recruitment of macrophages, resulting in a tenfold decrease in the number of fibers remaining in the lung. The increased number of macrophages in the chrysotile/sanded joint exposure group was confirmed histologically, with this being the only exposure-related histological finding reported. PMID:18788018

Bernstein, D. M.; Donaldson, K.; Decker, U.; Gaering, S.; Kunzendorf, P.; Chevalier, J.; Holm, S. E.

2008-01-01

335

A biopersistence study following exposure to chrysotile asbestos alone or in combination with fine particles.  

PubMed

In designing a study to evaluate the inhalation biopersistence of a chrysotile asbestos that was used as a component of a joint-compound, a feasibility study was initiated to evaluate the short-term biopersistence of the chrysotile alone and of the chrysotile in combination with the sanded reformulated joint-compound. Two groups of Wistar rats were exposed to either 7RF3 chrysotile (Group 2) or to 7RF3 chrysotile combined with aerosolized sanded joint-compound (Group 3). In addition, a control group was exposed to filtered-air. The chrysotile used in the Ready Mix joint compound is rapidly removed from the lung. The chrysotile alone exposure group had a clearance half-time of fibers L > 20 microm of 2.2 days; in the chrysotile plus sanded exposure group the clearance half-time of fibers L > 20 microm was 2.8 days. However, across all size ranges there was approximately an order of magnitude decrease in the mean number of fibers remaining in the lungs of Group 3 as compared to Group 2 despite similiar aerosol exposures. Histopathological examination showed that the chrysotile exposed lungs had the same appearance as the filtered-air controls. This study uniquely illustrates that additional concurrent exposure to an aerosol of the sanded joint-compound, with large numbers of fine-particles depositing in the lungs, accelerates the recruitment of macrophages, resulting in a tenfold decrease in the number of fibers remaining in the lung. The increased number of macrophages in the chrysotile/sanded joint exposure group was confirmed histologically, with this being the only exposure-related histological finding reported. PMID:18788018

Bernstein, D M; Donaldson, K; Decker, U; Gaering, S; Kunzendorf, P; Chevalier, J; Holm, S E

2008-09-01

336

Long-term sand supply to Coachella Valley Fringe-toed Lizard Habitat in the Northern Coachella Valley, California  

USGS Publications Warehouse

The Coachella Valley fringe-toed lizard (Uma inornata) is a federally listed threatened species that inhabits active sand dunes in the vicinity of Palm Springs, California. The Whitewater Floodplain and Willow Hole Reserves provide some of the primary remaining habitat for this species. The sediment-delivery system that creates these active sand dunes consists of fluvial depositional areas fed episodically by ephemeral streams. Finer fluvial sediments (typically sand size and finer) are mobilized in a largely unidirectional wind field associated with strong westerly winds through San Gorgonio Pass. The fluvial depositional areas are primarily associated with floodplains of the Whitewater?San Gorgonio Rivers and Mission Creek?Morongo Wash; other small drainages also contribute fluvial sediment to the eolian system. The eolian dunes are transitory as a result of unidirectional sand movement from the depositional areas, which are recharged with fine-grained sediment only during episodic floods that typically occur during El Ni?o years. Eolian sand moves primarily from west to east through the study area; the period of maximum eolian activity is April through June. Wind speed varies diurnally, with maximum velocities typically occurring during the afternoon. Development of alluvial fans, alteration of stream channels by channelization, in-stream gravel mining, and construction of infiltration galleries were thought to reduce the amount of fluvial sediment reaching the depositional areas upwind of Uma habitat. Also, the presence of roadways, railroads, and housing developments was thought to disrupt or redirect eolian sand movement. Most of the sediment yield to the fluvial system is generated in higher elevation areas with little or no development, and sediment yield is affected primarily by climatic fluctuations and rural land use, particularly livestock grazing and wildfire. Channelization benefits sediment delivery to the depositional plains upwind of the reserves by minimizing in-channel sediment storage on the alluvial fans. The post-development annual sediment yield to the Whitewater and Mission Creek?Morongo Wash depositional areas are 3.5 and 1.5 million ft3/yr, respectively, covering each depositional area to a depth of 0.2 to 0.4 in. Given existing sand-transport rates, this material could be depleted by eolian processes in 8 to 16 months, a rate consistent with the presence of persistent sand dunes. However, these depletion times are likely minimum estimates, as some eolian sand is seen to persist in the immediate vicinity of depositional areas for longer time periods. Transport rates may be reduced by the presence of vegetation and other windbreaks. Because they are perpendicular to prevailing winds, the infiltration galleries on Whitewater River trap fluvial and eolian sediment, reducing sediment availability. Also, the presence of the railroad and Interstate 10 redirect eolian sand movement to the southeast along their corridors,potentially eliminating the Whitewater depositional area as a sand source for the Willow Hole Reserve. Using directional wind data, we discuss the potential for eolian sand transport from the Mission Creek?Morongo Wash depositional area to Willow Hole.

Griffiths, Peter G.; Webb, Robert H.; Lancaster, Nicholas; Kaehler, Charles A.; Lundstrom, Scott C.

2002-01-01

337

Characterization of the L-1 sand using well logs and amplitude attribute analysis  

E-print Network

-T SAN A' 100' TOP OF SAND BASE OF SANO Fig. 5. Cross section (A-A') through inferred channel. The L-1 sand in Wells J and I are both interpreted to be channel sands. WeHs H and F lie outside the channel. The L-1 sand in Well F is interpreted... OF SAND 12 16 GMUP NUMBER F'ig. 13. Decrease in amplitude (dim spot) resulting from an oii-filled sand. The upper figure is a depositional model. The lower figure is the seismic respiinse 26 GAS SAND BRNE SAND '-::::: SHALE TOP OF SAND 12 16...

Ratliff, Thomas Lee

1989-01-01

338

Dust control effectiveness of drywall sanding tools.  

PubMed

In this laboratory study, four drywall sanding tools were evaluated in terms of dust generation rates in the respirable and thoracic size classes. In a repeated measures study design, 16 participants performed simulated drywall finishing tasks with each of four tools: (1) ventilated sander, (2) pole sander, (3) block sander, and (4) wet sponge. Dependent variables of interest were thoracic and respirable breathing zone dust concentrations. Analysis by Friedman's Test revealed that the ventilated drywall sanding tool produced significantly less dust, of both size classes, than did the other three tools. The pole and wet sanders produced significantly less dust of both size classes than did the block sander. The block sander, the most commonly used tool in drywall finishing operations, produced significantly more dust of both size classes than did the other three tools. When compared with the block sander, the other tools offer substantial dust reduction. The ventilated tool reduced respirable concentrations by 88% and thoracic concentrations by 85%. The pole sander reduced respirable concentrations by 58% and thoracic by 50%. The wet sander produced reductions of 60% and 47% in the respirable and thoracic classes, respectively. Wet sponge sanders and pole sanders are effective at reducing breathing-zone dust concentrations; however, based on its superior dust control effectiveness, the ventilated sander is the recommended tool for drywall finishing operations. PMID:19367481

Young-Corbett, Deborah E; Nussbaum, Maury A

2009-07-01

339

Solvent extraction of bitumen from tar sands  

SciTech Connect

This paper reports on the measurement of mass transfer rates for the extraction of bitumen from tar sands using organic solvents. The experiment was carried out in an agitated vessel using a six-blade turbine mixer on a laboratory scale. To facilitate the determination of absolute mass transfer coefficients, tar sands were specially prepared in the form of spherical particles so that mass transfer area can be computed. The variables investigated in the study included: (1) solvent type (kerosene, toluene, benzene), (2) stirrer speed, 25 rpm to 1000 rpm, and (3) particle diameter, 0.4 cm to 1.2 cm. The results indicated that solvency power varied markedly with the various solvents used and that high aromatic content promoted rapid dissolution when compared with paraffinic solvents. The mass transfer rates increased with increasing stirrer speed in accordance with the relationship: k {alpha} N{sup 0.56} where k is the mass transfer coefficient and N the stirrer speed. Increasing particle diameter also resulted in decreased mass transfer rates. The results were satisfactorily correlated in terms of a Frossling type equation, Sh {alpha} Re{sub p}{sup a}Sc{sup b}.

Hoon, A.Y.; Thomas, S. [Univ. of West Indies, St. Augustine (Trinidad and Tobago)

1995-12-31

340

TESTING OF TMR SAND MANTIS FINAL REPORT  

SciTech Connect

Screening tests of Sand Mantis candidate materials selected for erosion resistance have been completed. The results of this testing identified that over a relatively short period of operation (<1 hour), measurable erosion will occur in each of the candidate zoom tube materials given equal operating exposure. Additionally, this testing has shown that erosion of the rubber discharge hose directly downstream of the vehicle could be expected to limit the service life of the discharge hose. On the basis of these test results, SRNL recommends the following; {lg_bullet} redesign of critical system components (e.g., zoom tube, discharge hose) should be conducted to improve system characteristics relative to erosion and capitalize on the results of this testing, {lg_bullet} continued efforts to deploy the Sand Mantis should include testing to better define and optimize operating parameters, and gain an understanding of system dynamics, {lg_bullet} discontinue wear testing with the selected materials pending redesign of critical system components (1st recommendation) and inclusion of other candidate materials. The final selection of additional candidate materials should be made following design changes, but might include a Stellite alloy or zirconia.

Krementz, D; William Daugherty, W

2007-06-12

341

Microstructural characterization of a Canadian oil sand  

E-print Network

The microstructure of oil sand samples extracted at a depth of 75 m from the estuarine Middle McMurray formation (Alberta, Canada) has been investigated by using high resolution 3D X-Ray microtomography ($\\mu$CT) and Cryo Scanning Electron Microscopy (CryoSEM). $\\mu$CT images evidenced some dense areas composed of highly angular grains surrounded by fluids that are separated by larger pores full of gas. 3D Image analysis provided in dense areas porosity values compatible with in-situ log data and macroscopic laboratory determinations, showing that they are representative of intact states. $\\mu$CT hence provided some information on the morphology of the cracks and disturbance created by gas expansion. The CryoSEM technique, in which the sample is freeze fractured within the SEM chamber prior to observation, provided pictures in which the (frozen) bitumen clearly appears between the sand grains. No evidence of the existence of a thin connate water layer between grains and the bitumen, frequently mentioned in th...

Dinh, Hong Doan; Nauroy, Jean-François; Tang, Anh-Minh; Souhail, Youssef; 10.1139/T2012-072

2013-01-01

342

Autumn Frost, North Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

Autumn in the martian northern hemisphere began around August 1, 1999. Almost as soon as northern fall began, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) started documenting the arrival of autumn frost--a precursor to the cold winter that will arrive in late December 1999. The first features to become covered by frost were the sand dunes that surround the north polar ice cap. The dunes seen here would normally appear very dark--almost black--except when covered by frost. Why the dunes begin to frost sooner than the surrounding surfaces is a mystery: perhaps the dunes contain water vapor that emerges from the sand during the day and condenses again at night. This picture shows dunes near 74.7oN, 61.4oW at a resolution of about 7.3 meters (24 feet) per pixel. The area covered is about 3 km (1.9 mi) across and is illuminated from the upper right. The picture appears to be somewhat fuzzy and grainy because the dunes here are seen through the thin haze of the gathering north polar winter hood (i.e., clouds).

1999-01-01

343

Three-link Swimming in Sand  

NASA Astrophysics Data System (ADS)

Many animals move within in granular media such as desert sand. Recent biological experiments have revealed that the sandfish lizard uses an undulatory gait to swim within sand. Models reveal that swimming occurs in a frictional fluid in which inertial effects are small and kinematics dominate. To understand the fundamental mechanics of swimming in granular media (GM), we examine a model system that has been well-studied in Newtonian fluids: the three-link swimmer. We create a physical model driven by two servo-motors, and a discrete element simulation of the swimmer. To predict optimal gaits we use a recent geometric mechanics theory combined with empirically determined resistive force laws for GM. We develop a kinematic relationship between the swimmer's shape and position velocities and construct connection vector field and constraint curvature function visualizations of the system dynamics. From these we predict optimal gaits for forward, lateral and rotational motion. Experiment and simulation are in accord with the theoretical predictions; thus geometric tools can be used to study locomotion in GM.

Hatton, R. L.; Ding, Yang; Masse, Andrew; Choset, Howie; Goldman, Daniel

2011-11-01

344

Direct numerical simulations of aeolian sand ripples.  

PubMed

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

Durán, Orencio; Claudin, Philippe; Andreotti, Bruno

2014-11-01

345

Aeolian sand transport: Experiment and Theory  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

346

GPS Antennas Small Fine Arm  

E-print Network

Mechanism Bus UnitsEF ine Arm StageF Experiments Japanese Experiment Module (JEM)/Kibo (Hope) Japan~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Berthed to Node 2 GPS Antennas Small Fine Arm Main Arm Control and Life-Support/Thermal Control System Rack RMS Console Experiment Racks Communications Rack

347

The flux profile of a blowing sand cloud: a wind tunnel investigation  

Microsoft Academic Search

The flux profile of a blowing sand cloud, or the variation of blown sand flux with height, is the reflection of blown sand particles that move in different trajectories, and also the basis for checking drifting sand. Here we report the wind tunnel results of systematic tests of the flux profiles of different sized sands at different free-stream wind velocities.

Zhibao Dong; Xiaoping Liu; Hongtao Wang; Aiguo Zhao; Xunming Wang

2003-01-01

348

Artificial Sand Pictures -A Complex Systems Simulation Brad Pearce and Ken Hawick  

E-print Network

Pictures Sand pictures are made from a mix of coloured sands and water or oil sandwiched between two sheets sand picture. The sand picture system is essentially a complex fluid - with a colloidal suspension of sand particles contained in water or oil. Complex Fluids Modelling complex fluids is a challenging

Hawick, Ken

349

Faecal indicator bacteria enumeration in beach sand: a comparison study of extraction methods in medium to coarse sands  

PubMed Central

Aims The absence of standardized methods for quantifying faecal indicator bacteria (FIB) in sand hinders comparison of results across studies. The purpose of the study was to compare methods for extraction of faecal bacteria from sands and recommend a standardized extraction technique. Methods and Results Twenty-two methods of extracting enterococci and Escherichia coli from sand were evaluated, including multiple permutations of hand shaking, mechanical shaking, blending, sonication, number of rinses, settling time, eluant-to-sand ratio, eluant composition, prefiltration and type of decantation. Tests were performed on sands from California, Florida and Lake Michigan. Most extraction parameters did not significantly affect bacterial enumeration. anova revealed significant effects of eluant composition and blending; with both sodium metaphosphate buffer and blending producing reduced counts. Conclusions The simplest extraction method that produced the highest FIB recoveries consisted of 2 min of hand shaking in phosphate-buffered saline or deionized water, a 30-s settling time, one-rinse step and a 10 : 1 eluant volume to sand weight ratio. This result was consistent across the sand compositions tested in this study but could vary for other sand types. Significance and Impact of the Study Method standardization will improve the understanding of how sands affect surface water quality. PMID:19659700

Boehm, A.B.; Griffith, J.; McGee, C.; Edge, T.A.; Solo-Gabriele, H.M.; Whitman, R.; Cao, Y.; Getrich, M.; Jay, J.A.; Ferguson, D.; Goodwin, K.D.; Lee, C.M.; Madison, M.; Weisberg, S.B.

2009-01-01

350

Southern Fine Particulate Monitoring Project  

SciTech Connect

This final project report presents experimental details, results and analysis of continuous onsite ambient fine particulate data at the North Birmingham sampling site during the October, 2001-September, 2002 study period.The host site for these measurement activities is the North Birmingham PM monitoring station by the Jefferson County Health Department in Birmingham, AL.The continuous data include PM{sub 2.5} mass concentrations measured by TEOM, particle sulfate using the R&P 8400S monitor, particle size distributions measured by SMPS and APS monitors, and PM{sub 2.5} light scattering extinction coefficient as measured by nephelometer. During the course of the project, measurement intercomparison data were developed for these instruments and several complementary measurements at the site. The report details the instrument set and operating procedures and describes the resulting data. Report subsections present an overview summary of the data, followed by detailed description of the systematic time behavior of PM{sub 2.5} and other specific particulate size fractions. Specific subsections are included for particle size distribution, light scattering, and particle sulfate data. The final subsection addresses application of the measurements to the practical questions of fine PM generation and transport, source attribution, and PM{sub 2.5} management strategies.

Ashley Williamson

2003-05-31

351

Curiosity at Gale Crater, Mars: Characterization and Analysis of the Rocknest Sand Shadow  

NASA Astrophysics Data System (ADS)

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.

Blake, D. F.; Morris, R. V.; Kocurek, G.; Morrison, S. M.; Downs, R. T.; Bish, D.; Ming, D. W.; Edgett, K. S.; Rubin, D.; Goetz, W.; Madsen, M. B.; Sullivan, R.; Gellert, R.; Campbell, I.; Treiman, A. H.; McLennan, S. M.; Yen, A. S.; Grotzinger, J.; Vaniman, D. T.; Chipera, S. J.; Achilles, C. N.; Rampe, E. B.; Sumner, D.; Meslin, P.-Y.; Maurice, S.; Forni, O.; Gasnault, O.; Fisk, M.; Schmidt, M.; Mahaffy, P.; Leshin, L. A.; Glavin, D.; Steele, A.; Freissinet, C.; Navarro-González, R.; Yingst, R. A.; Kah, L. C.; Bridges, N.; Lewis, K. W.; Bristow, T. F.; Farmer, J. D.; Crisp, J. A.; Stolper, E. M.; Des Marais, D. J.; Sarrazin, P.; Agard, Christophe; Alves Verdasca, José Alexandre; Anderson, Robert; Anderson, Ryan; Archer, Doug; Armiens-Aparicio, Carlos; Arvidson, Ray; Atlaskin, Evgeny; Atreya, Sushil; Aubrey, Andrew; Baker, Burt; Baker, Michael; Balic-Zunic, Tonci; Baratoux, David; Baroukh, Julien; Barraclough, Bruce; Bean, Keri; Beegle, Luther; Behar, Alberto; Bell, James; Bender, Steve; Benna, Mehdi; Bentz, Jennifer; Berger, Gilles; Berger, Jeff; Berman, Daniel; Blanco Avalos, Juan Jose; Blaney, Diana; Blank, Jen; Blau, Hannah; Bleacher, Lora; Boehm, Eckart; Botta, Oliver; Böttcher, Stephan; Boucher, Thomas; Bower, Hannah; Boyd, Nick; Boynton, Bill; Breves, Elly; Bridges, John; Brinckerhoff, William; Brinza, David; Brunet, Claude; Brunner, Anna; Brunner, Will; Buch, Arnaud; Bullock, Mark; Burmeister, Sönke; Cabane, Michel; Calef, Fred; Cameron, James; Cantor, Bruce; Caplinger, Michael; Rodríguez, Javier Caride; Carmosino, Marco; Blázquez, Isaías Carrasco; Charpentier, Antoine; Choi, David; Clark, Benton; Clegg, Sam; Cleghorn, Timothy; Cloutis, Ed; Cody, George; Coll, Patrice; Conrad, Pamela; Coscia, David; Cousin, Agnès; Cremers, David; Cros, Alain; Cucinotta, Frank; d'Uston, Claude; Davis, Scott; Day, Mackenzie; Juarez, Manuel de la Torre; DeFlores, Lauren; DeLapp, Dorothea; DeMarines, Julia; Dietrich, William; Dingler, Robert; Donny, Christophe; Drake, Darrell; Dromart, Gilles; Dupont, Audrey; Duston, Brian; Dworkin, Jason; Dyar, M. Darby; Edgar, Lauren; Edwards, Christopher; Edwards, Laurence; Ehlmann, Bethany; Ehresmann, Bent; Eigenbrode, Jen; Elliott, Beverley; Elliott, Harvey; Ewing, Ryan; Fabre, Cécile; Fairén, Alberto; Farley, Ken; Fassett, Caleb; Favot, Laurent; Fay, Donald; Fedosov, Fedor; Feldman, Jason; Feldman, Sabrina; Fitzgibbon, Mike; Flesch, Greg; Floyd, Melissa; Flückiger, Lorenzo; Fraeman, Abby; Francis, Raymond; François, Pascaline; Franz, Heather; French, Katherine Louise; Frydenvang, Jens; Gaboriaud, Alain; Gailhanou, Marc; Garvin, James; Geffroy, Claude; Genzer, Maria; Godber, Austin; Goesmann, Fred; Golovin, Dmitry; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Gondet, Brigitte; Gordon, Suzanne; Gorevan, Stephen; Grant, John; Griffes, Jennifer; Grinspoon, David; Guillemot, Philippe; Guo, Jingnan; Gupta, Sanjeev; Guzewich, Scott; Haberle, Robert; Halleaux, Douglas; Hallet, Bernard; Hamilton, Vicky; Hardgrove, Craig; Harker, David; Harpold, Daniel; Harri, Ari-Matti; Harshman, Karl; Hassler, Donald; Haukka, Harri; Hayes, Alex; Herkenhoff, Ken; Herrera, Paul; Hettrich, Sebastian; Heydari, Ezat; Hipkin, Victoria; Hoehler, Tori; Hollingsworth, Jeff; Hudgins, Judy; Huntress, Wesley; Hurowitz, Joel; Hviid, Stubbe; Iagnemma, Karl; Indyk, Steve; Israël, Guy; Jackson, Ryan; Jacob, Samantha; Jakosky, Bruce; Jensen, Elsa; Jensen, Jaqueline Kløvgaard; Johnson, Jeffrey; Johnson, Micah; Johnstone, Steve; Jones, Andrea; Jones, John; Joseph, Jonathan; Jun, Insoo; Kahanpää, Henrik; Kahre, Melinda; Karpushkina, Natalya; Kasprzak, Wayne; Kauhanen, Janne; Keely, Leslie; Kemppinen, Osku; Keymeulen, Didier; Kim, Myung-Hee; Kinch, Kjartan; King, Penny; Kirkland, Laurel; Koefoed, Asmus; Köhler, Jan; Kortmann, Onno; Kozyrev, Alexander; Krezoski, Jill; Krysak, Daniel; Kuzmin, Ruslan; Lacour, Jean Luc; Lafaille, Vivian; Langevin, Yves; Lanza, Nina; Lasue, Jeremie; Le Mouélic, Stéphane; Lee, Ella Mae; Lee, Qiu-Mei; Lees, David; Lefavor, Matthew; Lemmon, Mark; Lepinette Malvitte, Alain; Léveillé, Richard; Lewin-Carpintier, Éric; Li, Shuai; Lipkaman, Leslie; Little, Cynthia; Litvak, Maxim; Lorigny, Eric; Lugmair, Guenter; Lundberg, Angela; Lyness, Eric; Maki, Justin; Malakhov, Alexey; Malespin, Charles; Malin, Michael; Mangold, Nicolas; Manning, Heidi; Marchand, Geneviève; Marín Jiménez, Mercedes; Martín García, César; Martin, Dave; Martin, Mildred; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Mauchien, Patrick; McAdam, Amy; McCartney, Elaina; McConnochie, Timothy; McCullough, Emily; McEwan, Ian

2013-09-01

352

Curiosity at Gale Crater, Mars: Characterization and Analysis of the Rocknest Sand Shadow  

NASA Technical Reports Server (NTRS)

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MER) Spirit and Opportunity. The fraction of sand <150 micron in size contains approx. 55% crystalline material consistent with a basaltic heritage, and approx. 45% X-ray amorphous material. The amorphous component of Rocknest is Fe-rich and Si-poor, and is the host of the volatiles (H2O, O2, SO2, CO2, and Cl) detected by the Surface Analysis at Mars (SAM) instrument and of the fine-grained nanophase oxide (npOx) component first described from basaltic soils analyzed by MER. The similarity between soils and aeolian materials analyzed at Gusev crater, Meridiani Planum and Gale crater implies locally sourced, globally similar basaltic materials, or globally and regionally sourced basaltic components deposited locally at all three locations.

Blake, David F.; Morris, Richard V.; Kocurek, G.; Morrison, S. M.; Downs, R. T.; Bish, D.; Ming, D. W.; Edgett, K. S.; Rubin, D.; Goetz, W.; Madsen, M. B.; Sullivan, R.; Gellert, R.; Campbell, I.; Treiman, A. H.; McLennan, S. M.; Yen, A. S.; Grotzinger, J.; Vaniman, D. T.; Chipera, S. J.; Achilles, C. N.; Rampe, E. B.; Sumner, D.; Meslin, P. -Y.; Maurice, S.; Forni, O.; Gasnault, O.; Fisk, M.; Schmidt, M.; Mahaffy, P.; Leshin, L. A.; Glavin, D.; Steele, A.; Freissinet, C.; Navarro-Gonzalez, R.; Yingst, R. A.; Kah, L. C.; Bridges, N.; Lewis, K. W.; Bristow, T. F.; Farmer, J. D.; Crisp, J. A.; Stolper, E. M.; DesMarais, D. J.; Sarrazin, P.

2013-01-01

353

Enhancing Simulation of Sand Behavior through 3D Subdivision Techniques  

NASA Astrophysics Data System (ADS)

Through the use of modern computer graphics, visualization and parallel computation continue to provide academic disciplines with new techniques to work with raw data. This is particularly true in the earth and planetary sciences as many researchers are using graphics hardware to process large amounts of data for analysis. Thus, there is an increasing demand for collaboration between computer graphics and the earth sciences. Recognizing this opportunity, we are collaborating with the Oregon Space Grant and IGERT Ecosystem Informatics programs to investigate new techniques for simulating the behavior of sand. In addition, we are also collaborating with the Jet Propulsion Laboratory's (JPL) DARTS Lab to exchange ideas and gain feedback on our work. The DARTS Lab specializes in planetary vehicle simulation, such as the Mars rovers. This simulation utilizes a virtual "sand box" to test how planetary rovers respond to different terrains while traversing them. Unfortunately, this simulation is unable to fully mimic the harsh, sandy environments of those found on Mars. Ideally, these simulations should allow a rover to interact with the sand beneath it, providing further insight into its performance. In particular, there may be situations where a rover may become stuck in sand due to lack of friction between the sand and wheels. Thus, we have been developing a sand simulation framework to mimic the behavior of sand. Treated naively, this is a computationally complex problem, especially if trying to represent millions or even billions of sand particles interacting with each other. However, we can use graphics processing units (GPUs) on modern graphics hardware to subdivide and parallelize the problem. Basically, our idea is to subdivide regions of sand similar to a Level of Detail (LoD) method. Put another way, the more active the sand is in interacting with outside objects, the smaller the region the sand will be represented in the simulation. For example, let's say there is a planetary rover interacting with our sand simulation. Sand that is actively interacting with a rover wheel will be represented as an individual particle whereas sand that is further under the surface will be represented by a 3D region that represents several particles. As a particle region moves closer to the surface, it subdivides into smaller regions until individual sand particles are left. Our technique uses a variation of a 3D Voronoi decomposition in order to generate regions of sand. However, in our iteration, sand on the surface will be subdivided as particles whereas sand deeper into the earth will be subdivided into subsequently larger regions. By doing this, we can represent many more particles of sand than through traditional means. In addition, we have the added benefit of being able to parallelize the interaction between active particles through the use of the GPU. As such, not only are we able to represent vast amounts of sand, but we can also utilize more individual particles at the interaction source. An enhanced sand model through the use of subdivision techniques and GPUs has great potential for earth science research. Our collaborations with JPL have helped to further refine our simulation framework. As a result, we feel this work could also benefit other earth science fields, such as understanding sinkholes and debris flows.

Clothier, M.; Bailey, M.

2011-12-01

354

Fifteen-year trends in criteria air pollutants in oil sands communities of Alberta, Canada.  

PubMed

An investigation of ambient air quality was undertaken at three communities within the Athabasca Oil Sands Region (AOSR) of Alberta, Canada (Fort McKay, Fort McMurray, and Fort Chipewyan). Daily and seasonal patterns and 15-year trends were investigated for several criteria air pollutants over the period of 1998 to 2012. A parametric trend detection method using percentiles from frequency distributions of 1h concentrations for a pollutant during each year was used. Variables representing 50th, 65th, 80th, 90th, 95th and 98th percentile concentrations each year were identified from frequency distributions and used for trend analysis. Small increasing concentration trends were observed for nitrogen dioxide (<1ppb/year) at Fort McKay and Fort McMurray over the period consistent with increasing emissions of oxides of nitrogen (ca. 1000tons/year) from industrial developments. Emissions from all oil sands facilities appear to be contributing to the trend at Fort McKay, whereas both emissions from within the community (vehicles and commercial) and oil sands facility emissions appear to be contributing to the trend at Fort McMurray. Sulfur dioxide (SO2) emissions from industrial developments in the AOSR were unchanged during the period (101,000±7000tons/year; mean±standard deviation) and no meaningful trends were judged to be occurring at all community stations. No meaningful trends occurred for ozone and fine particulate matter (PM2.5) at all community stations and carbon monoxide at one station in Fort McMurray. Air quality in Fort Chipewyan was much better and quite separate in terms of absence of factors influencing criteria air pollutant concentrations at the other community stations. PMID:25454237

Bari, Md; Kindzierski, Warren B

2015-01-01

355

Reproductive development of yellow perch (Perca flavescens) exposed to oil sands-affected waters.  

PubMed

In similar experiments conducted in 1996 and 2009, yellow perch (Perca flavescens) were stocked into two experimental systems: a demonstration lake where oil sands fine tailings were capped with natural water and a lake in a watershed containing bitumen-bearing sodic clays. In both experiments, yellow perch were captured in May from a nearby reservoir and released into the experimental ponds. Perch were recaptured in the experimental systems, the source lake, and two reference lakes in late September and lethally sampled to examine reproductive parameters. In the 1996 experiment, gonad size and steroid hormones were not affected in either pond environment. In the 2009 experiment, male perch in the water-capped tailings pond showed a significant reduction in the testicular development and reductions in circulating testosterone and 11-ketotestosterone, while no reductions were seen in the second experimental pond. No changes were observed in ovarian size or circulating steroid levels in female perch. In the pond containing tailings, the release of water from underlying tailings caused approximately a twofold increase in salinity, alkalinity, and naphthenic acids, and a pH increase from 8.4 to 9.4 over the 13-year period of the study. In the pond influenced by unextracted oil sands materials, total dissolved solids, major ions, and pH did not change substantially. However, naphthenic acids in this system dropped more than twofold post-watershed reclamation. Because the selective reproductive effect observed in male perch in the experimental end-pit lake were accompanied by increases in naphthenic acids, alkalinity, and pH, a specific cause cannot be determined. The present study adds to the evidence, suggesting the presence of endocrine-disrupting substances in oil sands. PMID:22189895

Heuvel, Michael R van den; Hogan, Natacha S; Roloson, Scott D; Kraak, Glen J Van Der

2012-03-01

356

Monitoring CO2 gas-phase injection in a shallow sand aquifer using cross borehole GPR  

NASA Astrophysics Data System (ADS)

An important issue that needs attention in designing effective storage schemes for CO2 storage in deep geologic formations is risk assessment of potential leakage. Leaking gas may threat surface and groundwater sources as well as vegetation. We have designed an experiment where we were track the movement of an injected CO2 gas-phase in an unconfined aquifer using cross borehole GPR. The test site is located in the south-western part of Denmark. The aquifer at the site consists of fine to coarse glacial melt water sands, which are staggered in slightly tilted layers. In all experiments gas was injected for 48 hours with flow rates between 9-16 g/min. The screen of the injection well is 10 m below ground level or 8 m below the water table. Initially an array of four GPR boreholes was installed around the injection well and subsequently two extra GPR Boreholes were installed downwards of dominating gas flow direction. GPR-data were acquired in zero offset (1D) and multiple offset (2D) configurations prior and during the injection. To support the GPR measurements 12 Decagon 5-TE soil moisture probes were installed at various dept for the last experiments. Both set of GPR data showed that a plume developed at the depth of the injection screen and that the injected gas primarily spread towards South-East. The geology consists of slightly tilting layers, which may cause migration of the gas plume along the interface of the coarse and fine sand and out of the monitoring area. The results confirmed the notion that geological heterogeneity has a critical impact on the gas migration pattern. The gas plume migration was further analysed by the multi-phase numerical code T2VOC a part of the TOUGH family.

Lassen, R. N.; Looms, M. C.; Jensen, K. H.; Sonnenborg, T.

2012-12-01

357

Monitoring CO2 gas-phase injection in a shallow sand aquifer using cross borehole GPR.  

NASA Astrophysics Data System (ADS)

An important issue that needs attention in designing effective storage schemes for CO2 storage in deep geologic formations is risk assessment of potential leakage. Leaking gas may threat surface and groundwater sources as well as vegetation. We have designed an experiment where we were track the movement of an injected CO2 gas-phase in an unconfined aquifer using cross borehole GPR. The first preliminary results from the pilot experiment will be presented here. The test site is located near in the south-western part of Denmark. The aquifer at the site is consists of fine to coarse glacial melt water sands, which are staggered in slightly tilted layers. Gas was injected for 48 hours with flow rates of 5 l/min at the start of the experiment and up to 10+ l/min at the end of the experiment. The screen of the injection well is 10m below ground level or 8m below the water table. An array of four GPR boreholes is installed around the injection well. GPR-data were acquired in 1D and 2D configurations prior and during the injection. The GPR data shows that in five out of six 1D-panels a plume develops at the depth of the injection screen and the same behaviour is seen in the 2D panels. The results suggest that the injected gas primarily spreads towards South-East. The geology consists of slightly tilting layers, which may cause migration of the gas plume along the interface of the coarse and fine sand and out of the monitoring area. These initial results confirm the notion that even little heterogeneity may have a significant effect on the gas migration pattern.

Lassen, R. N.; Looms, M.; Jensen, K. H.; Sonnenborg, T.; Cahill, A.

2012-04-01

358

Factors influencing stable isotopes and growth of algae in oil sands aquatic reclamation.  

PubMed

Previous studies reported (15)N enrichment of biota in reclamation wetlands that contain oil sands processed material (e.g., processed water and tailings); however, there is little information on the factors controlling (15)N enrichment in these systems. In this microcosm study, the aim was to examine stable C and N isotopes and growth (chlorophyll a [chl a] and dry weight) of algae as a function of exposure to different sources and concentrations of water-soluble fractions (WSF) derived from tailings. Two sources of tailings including mature fine tailings (MFT) and consolidated tailings (CT) and peat-mineral overburden were utilized to generate separate WSF that differed in water quality. In general, there was (15)N enrichment of filamentous algae along the increasing gradient of WSF/nutrient concentrations in both CT and peat microcosms, and among the different sources, algae were more (15)N enriched in CT WSF than in peat WSF. Growth of filamentous algae was inhibited at higher WSF concentrations, possibly due to reduced light availability at elevated levels of fine clay particles in MFT microcosms and colored dissolved organic carbon (DOC) in peat microcosms. Filamentous algae displayed lower biomass and (15)N depletion in 100% peat WSF. This study indicated that both the quality (source) and quantity of WSF affected algal growth and directly and/or indirectly influenced ?(15)N of algae. The distinct (15)N enrichment of primary producers derived from tailings suggest that stable N isotopes might be useful to trace exposure to oil sands processed material in biota that utilize these resources in reclaimed systems constructed with tailings or natural systems that receive tailings dyke seepage. PMID:25506635

Boutsivongsakd, Monique; Farwell, Andrea J; Chen, Hao; Dixon, D George

2015-01-01

359

A Mystery Unraveled: Booming Sand Dunes  

NASA Astrophysics Data System (ADS)

"Booming" sand dunes have intrigued travelers and scientist for centuries. These dunes emit a persistent, low-frequency sound during a slumping event or a natural avalanche on the leeward face of the dune. The sound can last for several minutes and be audible from miles away. The resulting acoustic emission is characterized by a dominant audible frequency (70 - 105 Hz) and several higher harmonics. In the work of Vriend et al. (2007), seismic refraction experiments proved the existence of a multi-layer internal structure in the dune that acts as a waveguide for the acoustic energy. Constructive interference between the reflecting waves enables the amplification and sets the frequency of each boom. A relationship was established that correctly predicts the measured frequency in terms of the thickness (~ 2.0 m) and the seismic body wave velocity of the loose, dry surficial layer (~ 240 m/s) and the substrate half-space (~ 350 m/s). The current work highlights additional measurements and simulations supporting the waveguide model for booming sand dunes. Experiments with ground penetrating radar continuously display the subsurface features which confirm the layered subsurface structure within the dune. Cross-correlation analysis shows that the booming sound propagates at speeds close to the measured body wave velocity. Squeaking sounds, which are generated during the onset of the slide and precede the sustained booming emission, have been found to have distinctly different characteristics. These short bursts of sound are emitted at a lower frequency (50 - 65 Hz) and propagate at a lower propagation speed (125 m/s) than the booming emission. The acoustic and elastic wave propagation in the dune has been simulated with a finite difference code. The interaction between the air and the ground produces a coupling wave along the surface. The reflections in the surficial layer propagate in a dispersive band at a group velocity that is slower than the phase velocity of the layer. Different source mechanisms are used in order to simulate the squeaking and booming emission within the dune. špace{.1in} {\\footnotesize Vriend, N. M., M. L. Hunt, R. W. Clayton, C E. Brennen, K. S. Brantley, and A. Ruiz-Angulo (2007), Solving the mystery of booming sand dunes, Geophys. Res. Lett., 34, L16306, doi:10.1029/2007GL030276.}

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

2007-12-01

360

Properties of Desert Sand and CMAS Glass  

NASA Technical Reports Server (NTRS)

As-received desert sand from a Middle East country has been characterized for its phase composition and thermal stability. X-ray diffraction analysis showed the presence of quartz (SiO2), calcite (CaCO3), gypsum (CaSO4.2H2O), and NaAlSi3O8 phases in as-received desert sand and showed weight loss of approx. 35 percent due to decomposition of CaCO3 and CaSO4.2H2O when heated to 1400 C. A batch of as-received desert sand was melted into calcium magnesium aluminosilicate (CMAS) glass at approx. 1500 C. From inductively coupled plasma-atomic emission spectrometry, chemical composition of the CMAS glass was analyzed to be 27.8CaO-4MgO-5Al2O3-61.6SiO2-0.6Fe2O3-1K2O (mole percent). Various physical, thermal and mechanical properties of the glass have been evaluated. Bulk density of CMAS glass was 2.69 g/cc, Young's modulus 92 GPa, Shear modulus 36 GPa, Poisson's ratio 0.28, dilatometric glass transition temperature (T (sub g)) 706 C, softening point (T (sub d)) 764 C, Vickers microhardness 6.3 +/- 0.4 GPa, indentation fracture toughness 0.75 +/- 0.15 MPa.m (sup 1/2), and coefficient of thermal expansion (CTE) 9.8 x 10 (exp -6)/degC in the temperature range 25 to 700 C. Temperature dependence of viscosity has also been estimated from various reference points of the CMAS glass using the Vogel-Fulcher-Tamman (VFT) equation. The glass remained amorphous after heat treating at 850 C for 10 hr but crystallized into CaSiO3 and Ca-Mg-Al silicate phases at 900 C or higher temperatures. Crystallization kinetics of the CMAS glass has also been investigated by differential thermal analysis (DTA). Activation energies for the crystallization of two different phases in the glass were calculated to be 403 and 483 kJ/mol, respectively.

Bansal, Narottam P.; Choi, Sung R.

2014-01-01

361

Beach Sand Analysis for Indicators of Microbial Contamination  

EPA Science Inventory

Traditional beach monitoring has focused on water quality, with little attention paid to health risks associated with beach sand. Recent research has reported that fecal indicator bacteria, as well as human pathogens can be found in beach sand and may constitute a risk to human h...

362

Channel bed evolution and sediment transport under declining sand inputs  

Microsoft Academic Search

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

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

2006-01-01

363

An outbreak of sand impaction in postpartum dairy cows  

PubMed Central

Twenty-two cases of indigestion occurred in a 650-cow herd. Five cows had severe sand abomasal impaction, diagnosed by laparotomy. The pH of prepartum cows’ urine was < 6.0 and of sand 8.0. Feed showed a dietary cation-anion difference ? ?110 mEq/kg. After feeding management corrections, no more cases were diagnosed. PMID:17987969

Melendez, Pedro; Krueger, Traci; Benzaquen, Mauricio; Risco, Carlos

2007-01-01

364

Study of properties of sand asphalt using a torsional rheometer  

E-print Network

. In this work we have used the same Torsional Rheometer with some minor modifications in the design to measure some general properties of Sand Asphalt mixtures. Sand Asphalt mixtures, due to their non-linear viscoelastic character, exhibit `normal stress effects...

Kasula, Lavan Kumar Reddy

2004-11-15

365

Coastal Sand Dune Plant Ecology: Field Phenomena and Interpretation  

ERIC Educational Resources Information Center

Discusses the advantages and disadvantages of selecting coastal sand dunes as the location for field ecology studies. Presents a descriptive zonal model for seaboard sand dune plant communities, suggestions concerning possible observations and activities relevant to interpreting phenomena associated with these forms of vegetation, and additional…

McDonald, K.

1973-01-01

366

TECHNICAL NOTE Centrifuge cone penetration tests in sand  

E-print Network

TECHNICAL NOTE Centrifuge cone penetration tests in sand M. D. BOLTON,Ã? M. W. GUI,Ã? J. GARNIER,{ J. F. CORTE,{ G. BAGGE,{ J. LAUE} and R. RENZIk KEYWORDS: centrifuge modelling; in-situ testing; laboratory tests; piles; sands. INTRODUCTION Centrifuges have been widely adopted in modelling geotechnical

Bolton, Malcolm

367

31. PETIBONE SAND THROWING MACHINE BOX FLOOR GREY IRON FOUNDRY ...  

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

31. PETIBONE SAND THROWING MACHINE BOX FLOOR GREY IRON FOUNDRY FORCES CONDITIONED MOLDING SAND, AT HIGH VELOCITY, INTO MOLDS TOO BIG TO BE MADE ON ONE OF THE CONVEYOR SYSTEMS. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

368

Modelling of reoxidation inclusion formation in steel sand casting  

E-print Network

deoxidation inclusions (for which buoyancy is negligible) in continuous casting (rather than in shape castingModelling of reoxidation inclusion formation in steel sand casting A. J. Melendez, K. D. Carlson pouring, as well as their final locations on the surface of steel sand castings. Inclusions originate

Beckermann, Christoph

369

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

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

BLAISDELL SLOW SAND FILTER WASHING MACHINE. VIEW LOOKING WEST. THE NONHISTORIC CHEMICAL BUILDING IS SEEN IN THE BACKGROUND. - Yuma Main Street Water Treatment Plant, Blaisdell Slow Sand Filter Washing Machine, Jones Street at foot of Main Street, Yuma, Yuma County, AZ

370

PREEMERGENCE-APPLIED HERBICIDES AID SAND BLUESTEM ESTABLISHMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Controlling plant competition is critical to successful perennial grass establishment. Our objective was to determine the potential of several preemergence-applied herbicides to control annual weeds and aid sand bluestem (Andropogon hallii Hack.) establishment. Sand bluestem was seeded at the end ...

371

Sand impactions in a Saskatchewan beef cow-calf herd  

PubMed Central

Forty beef cows were reported to show signs of abdominal pain and discomfort over a period of 1 wk. Two of the affected animals died and on postmortem examination were found to be impacted with sand in their abomasum and small intestines. Sand-laden barley silage was found to be the cause of these impactions. PMID:21461212

Erickson, Nathan; Hendrick, Steven

2011-01-01

372

Documenting the global impacts of beach sand mining  

Microsoft Academic Search

For centuries, beach sand has been mined for use as aggregate in concrete, for heavy minerals, and for construction fill. The global extent and impact of this phenomenon has gone relatively unnoticed by academics, NGOs, and major news sources. Most reports of sand mining activities are found at the very local scale (if the mining is ever documented at all).

R. Young; A. Griffith

2009-01-01

373

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

NASA Astrophysics Data System (ADS)

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

Cui, Y.

2006-12-01

374

Microbially-accelerated consolidation of oil sands tailings. Pathway II: solid phase biogeochemistry.  

PubMed

Consolidation of clay particles in aqueous tailings suspensions is a major obstacle to effective management of oil sands tailings ponds in northern Alberta, Canada. We have observed that microorganisms indigenous to the tailings ponds accelerate consolidation of mature fine tailings (MFT) during active metabolism by using two biogeochemical pathways. In Pathway I, microbes alter porewater chemistry to indirectly increase consolidation of MFT. Here, we describe Pathway II comprising significant, direct and complementary biogeochemical reactions with MFT mineral surfaces. An anaerobic microbial community comprising Bacteria (predominantly Clostridiales, Synergistaceae, and Desulfobulbaceae) and Archaea (Methanolinea/Methanoregula and Methanosaeta) transformed Fe(III) minerals in MFT to amorphous Fe(II) minerals during methanogenic metabolism of an added organic substrate. Synchrotron analyses suggested that ferrihydrite (5Fe2O3. 9H2O) and goethite (?-FeOOH) were the dominant Fe(III) minerals in MFT. The formation of amorphous iron sulfide (FeS) and possibly green rust entrapped and masked electronegative clay surfaces in amended MFT. Both Pathways I and II reduced the surface charge potential (repulsive forces) of the clay particles in MFT, which aided aggregation of clays and formation of networks of pores, as visualized using cryo-scanning electron microscopy (SEM). These reactions facilitated the egress of porewater from MFT and increased consolidation of tailings solids. These results have large-scale implications for management and reclamation of oil sands tailings ponds, a burgeoning environmental issue for the public and government regulators. PMID:24711806

Siddique, Tariq; Kuznetsov, Petr; Kuznetsova, Alsu; Li, Carmen; Young, Rozlyn; Arocena, Joselito M; Foght, Julia M

2014-01-01

375

Power generation and oil sands process-affected water treatment in microbial fuel cells.  

PubMed

Oil sands process-affected water (OSPW), a product of bitumen isolation in the oil sands industry, is a source of pollution if not properly treated. In present study, OSPW treatment and voltage generation were examined in a single chamber air-cathode microbial fuel cell (MFC) under the effect of inoculated carbon source and temperature. OSPW treatment with an anaerobic sludge-inoculated MFC (AS-MFC) generated 0.55 ± 0.025 V, whereas an MFC inoculated with mature-fine tailings (MFT-MFC) generated 0.41 ± 0.01 V. An additional carbon source (acetate) significantly improved generated voltage. The voltage detected increased to 20-23% in MFCs when the condition was switched from ambient to mesophilic. The mesophilic condition increased OSPW treatment efficiency in terms of lowering the chemical oxygen demand and acid-extractable organics. Pyrosequencing analysis of microbial consortia revealed that Proteobacteria were the most abundant in MFCs and microbial communities in the AS-MFC were more diverse than those in the MFT-MFC. PMID:25103035

Choi, Jeongdong; Liu, Yang

2014-10-01

376

40 CFR 436.40 - Applicability; description of the industrial sand subcategory.  

...Applicability; description of the industrial sand subcategory. 436.40 Section 436...PROCESSING POINT SOURCE CATEGORY Industrial Sand Subcategory § 436.40 Applicability; description of the industrial sand subcategory. The provisions of...

2014-07-01

377

40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.  

...Applicability; description of the construction sand and gravel subcategory. 436.30 Section...PROCESSING POINT SOURCE CATEGORY Construction Sand and Gravel Subcategory § 436.30 Applicability; description of the construction sand and gravel subcategory. The...

2014-07-01

378

Method and apparatus for hydrocarbon recovery from tar sands  

DOEpatents

A method and apparatus for utilizing tar sands having a broad range of bitumen content is disclosed. More particularly, tar sands are pyrolyzed in a cyclone retort with high temperature gases recycled from the cyclone retort to produce oil and hydrocarbon products. The spent tar sands are then burned at 2000/degree/F in a burner to remove residual char and produce a solid waste that is easily disposable. The process and apparatus have the advantages of being able to utilize tar sands having a broad range of bitumen content and the advantage of producing product gases that are free from combustion gases and thereby have a higher heating value. Another important advantage is rapid pyrolysis of the tar sands in the cyclone so as to effectively utilize smaller sized reactor vessels for reducing capitol and operating costs. 1 fig., 1 tab.

Westhoff, J.D.; Harak, A.E.

1988-05-04

379

The effects of psammophilous plants on sand dune dynamics  

E-print Network

Psammophilous plants are special plants that flourish in sand moving environments. There are two main mechanisms by which the wind affects these plants: (i) sand drift exposes roots and covers branches--the exposed roots turn into new plants and the covered branches turn into new roots; both mechanisms result in an enhanced growth rate of the psammophilous plant cover of the dunes; (ii) strong winds, often associated with sand movement, tear branches and seed them in nearby locations, resulting in new plants and an enhanced growth rate of the psammophilous plant cover of the dunes. Despite their important role in dune dynamics, to our knowledge, psammophilous plants have never been incorporated into mathematical models of sand dunes. Here, we attempt to model the effects of these plants on sand dune dynamics. We construct a set of three ordinary differential equations for the fractions of surface cover of regular vegetation, biogenic soil crust and psammophilous plants. The latter reach their optimal growth u...

Bel, Golan

2013-01-01

380

Mapping sand and gravel pits in the Patuxent River watershed  

NASA Technical Reports Server (NTRS)

LANDSAT data from July 1973 and June 1978 for the Patuxent River Watershed of Maryland were processed in an effort to devise an economical method of monitoring the reclamation of sand and gravel pits. ASTEP-II and IDIMS software were utilized to derive signatures for sand and gravel pits and other land use/land cover types. Both unsupervised and supervised classifications of the two data sets were produced. Resultant statistics and color output products were compared in order to determine the extent of reclamation and expansion of sand and gravel pits over the five-year time span and to check the locations of more recent sand and gravel pits. Preliminary results indicate that, for a selected northern sub-acre, signatures derived for sand and gravel pits were nearly 90 percent accurate.

Schmidt, T. J.; Witt, R. G.

1981-01-01

381

Direct Production of Silicones From Sand  

SciTech Connect

Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

2001-09-30

382

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

383

Geohydrology of the High Energy Laser System Test Facility site, White Sands Missile Range, Tularosa Basin, south-central New Mexico  

USGS Publications Warehouse

The Yesum-HoHoman and Gypsum land (hummocky) soils at the High Energy Laser System Test Facility (HELSTF) represent wind deposits from recently desiccated lacustrine deposits and deposits from the ancestral Lake Otero. The upper 15-20 feet of the subsurface consists of varved gypsiferous clay and silt. Below these surfidai deposits the lithology consists of interbedded clay units, silty-clay units, and fine- to medium-grained quartz arenite units in continuous and discontinuous horizons. Clay horizons can cause perched water above the water table. Analyses of selected clay samples indicate that clay units are composed chiefly of kaolinire and mixed-layer illite/ smectite. The main aquifer is representative of a leaky-confined aquifer. Estimated aquifer properties are: transmissivity (T) = 780 feet squared per day, storage coefficient (S) = 3.1 x 10-3, and hydraulic conductivity (K) = 6.0 feet per day. Ground water flows south and southwest; the estimated hydraulic gradient is 5.3 feet per mile. Analyses of water samples indicate that ground water at the HELSTF site is brackish to slightly saline at the top of the main aquifer. Dissolved-solids concentration near the top of the main aquifer ranges from 5,940 to 11,800 milligrams per liter. Predominant ions are sodium and sulfate. At 815 feet below land surface, the largest dissolved-solids concentration measured is 111,000 milligrams per liter, which indicates increasing salinity with depth. Predominant ions are sodium and chloride.

Basabilvazo, G.T.; Nickerson, E.L.; Myers, R.G.

1994-01-01

384

Microbes in Beach Sands: Integrating Environment, Ecology and Public Health.  

PubMed

Beach sand is a habitat that supports many microbes, including viruses, bacteria, fungi and protozoa (micropsammon). The apparently inhospitable conditions of beach sand environments belie the thriving communities found there. Physical factors, such as water availability and protection from insolation; biological factors, such as competition, predation, and biofilm formation; and nutrient availability all contribute to the characteristics of the micropsammon. Sand microbial communities include autochthonous species/phylotypes indigenous to the environment. Allochthonous microbes, including fecal indicator bacteria (FIB) and waterborne pathogens, are deposited via waves, runoff, air, or animals. The fate of these microbes ranges from death, to transient persistence and/or replication, to establishment of thriving populations (naturalization) and integration in the autochthonous community. Transport of the micropsammon within the habitat occurs both horizontally across the beach, and vertically from the sand surface and ground water table, as well as at various scales including interstitial flow within sand pores, sediment transport for particle-associated microbes, and the large-scale processes of wave action and terrestrial runoff. The concept of beach sand as a microbial habitat and reservoir of FIB and pathogens has begun to influence our thinking about human health effects associated with sand exposure and recreational water use. A variety of pathogens have been reported from beach sands, and recent epidemiology studies have found some evidence of health risks associated with sand exposure. Persistent or replicating populations of FIB and enteric pathogens have consequences for watershed/beach management strategies and regulatory standards for safe beaches. This review summarizes our understanding of the community structure, ecology, fate, transport, and public health implications of microbes in beach sand. It concludes with recommendations for future work in this vastly under-studied area. PMID:25383070

Whitman, Richard; Harwood, Valerie J; Edge, Thomas A; Nevers, Meredith; Byappanahalli, Muruleedhara; Vijayavel, Kannappan; Brandão, João; Sadowsky, Michael J; Alm, Elizabeth Wheeler; Crowe, Allan; Ferguson, Donna; Ge, Zhongfu; Halliday, Elizabeth; Kinzelman, Julie; Kleinheinz, Greg; Przybyla-Kelly, Kasia; Staley, Christopher; Staley, Zachery; Solo-Gabriele, Helena M

2014-09-01

385

Mathematics Written in Sand Version of 22 Nov. 1983 File MathSand.pdf January 9, 2001 8:40 am Page 1 /49  

E-print Network

Mathematics Written in Sand Version of 22 Nov. 1983 File MathSand.pdf January 9, 2001 8:40 am Page 1 /49 MATHEMATICS WRITTEN IN SAND - the hp-15C, Intel 8087, etc. W. Kahan, University of California;Mathematics Written in Sand Version of 22 Nov. 1983 File MathSand.pdf January 9, 2001 8:40 am Page 2 /49 Three

California at Irvine, University of

386

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

PubMed

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

Ma, G S; Zheng, X J

2011-05-01

387

Fused silica fine grinding with low roughness  

NASA Astrophysics Data System (ADS)

Lithography-optics is one of the most complex optical systems. The fine grinding process is the most important step before polishing. Roughness and sub-surface damage (SSD) are essential outputs of fine grinding. We demonstrate the method that use fix abrasive cup tool with CNC grinding machine to complete the fine grinding process, even instead of lapping process. And experiment sample roughness can reach 23.40nm rms and Ra 18.554nm. The SSD estimate is about 2 ?m which is also smaller than commercial lapping process. The fine grinding output can satisfy the lithography optic fabrication demands and efficiently reduce the polishing time.

Dai, Lei; Gu, Yongqiang; Wu, Di

2014-08-01

388

Effect of bacterial adsorption on low frequency electrical properties of clean quartz sands and iron-oxide coated sands  

NASA Astrophysics Data System (ADS)

Low frequency electrical measurements (0.1-1000 Hz) were conducted to investigate the adsorption effect of Pseudomonas aeruginosa cells onto clean quartz sands and iron-oxide coated sands. The clean quartz sands showed a gradual increase in the microbial adsorption to mineral grains, concurrent with an increase of 13% in the imaginary conductivity component (?''). However, iron-oxide coated sands (20-100% by weight) showed a rapid increase in microbial adsorption with ?'' reaching a maximum of 37 % for the 80-100% iron coated sands. No significant changes were observed in the real conductivity component (?') due to microbial adsorption. A power law dependency was observed between the adsorbed cells and ?''. We suggest that the polarization results from the increase in the surface roughness and surface area of the grain due to bacteria sorption. These results suggest that low frequency electrical measurements can play an important role in assessing microbial transport in subsurface environments.

Abdel Aal, Gamal; Atekwana, Estella; Radzikowski, Sylvia; Rossbach, Silvia

2009-02-01

389

Tectonics and sedimentology along the Monkey River and Big Creek, southern Belize, Central America: Modern analog of select Morrow sands  

SciTech Connect

Big Creek is presently a relatively short river draining the flat coastal plain at the southern edge of the North American plate, south-central Belize. The recent sediments in this river consists of very fine-grained silts and clays derived from the local coastal plain. Offshore from the mouth of the Big Creek are shallow sand bars, channels, and eroding islands consisting of well-sorted, coarse sand comprised dominantly of feldspathic minerals. The location and geometry of these sands suggest that Big Creek was the fluvial source for this material. The sedimentology implication is that the nearshore and offshore parts of Big Creek represent a relatively large drowned deltaic complex, a modern analog of some lower Morrow depositional systems. Coarse feldspathic material found in the Cockscomb basin in the Maya Mountains is transported by the Swasey branch of the Monkey River toward the Big Creek drainage to the coast. However, the Swasey branch is abruptly diverted southward to intersect the present-day Monkey River. Drainage analysis suggests that structural features subsidiary to the Chixoy-Polochic fault zone bounding the North American plate may have diverted flow southward, beheading Big Creek. Field observations have not found any major relief changes which would have drainage analysis support tectonic diversion of the head waters of Big Creek into present-day Monkey River. Similar processes are hypothesized to have occurred during Morrow deposition.

Gries, J.C.; Full, W.E. (Wichita State Univ., KS (United States))

1991-08-01

390

Measured electric responses of unconsolidated layered and brine-saturated sand and sand-clay packs under continuous fluid flow conditions  

NASA Astrophysics Data System (ADS)

We have investigated the effects of pore solution concentration on the complex electric response of two different unconsolidated samples, layered sand and sand-clay in the frequency range from 30 kHz to 3 MHz. The electric parameters that describe the electric response of the samples—real part of permittivity, conductivity amplitude and phase—are obtained through two-electrode electric measurements. Plots of the conductivity amplitude and phase as a function of frequency show large variations with water saturation and NaCl concentrations. This sensitivity may be useful for the characterization of the vadose zone. Under continuous fluid flow conditions, first drainage and secondary imbibition cycles were conducted for the two three-layered samples saturated with saline water in three different NaCl solution concentrations at atmospheric pressure and temperatures between 21 °C and 22 °C. Electrode polarization distorted the measurements, particularly in the kHz range. The distortion becomes negligible above a limiting lower frequency, which depends on NaCl solution concentration and the kind of sample. To obtain the intrinsic behaviour of the samples, the electric permittivities were analyzed above the limiting frequencies. Analysis of the real part of electric permittivity versus saturation indicates that, with increasing salinity concentration, the real part of the electric permittivity increases. Also, the hysteretic effect, the difference between first drainage and second imbibition, becomes more pronounced and remains present at higher frequencies. For the two samples, we observed a different correlation between conductivity amplitude/phase spectra and pore fluid concentration for seven saturation levels, suggesting that conductivity amplitude/phase spectra contain information about water saturation, salt solution concentration, and geotechnical properties (e.g., fines content) of unconsolidated near-surface soils. A simplified five-parameter double Cole-Cole model could fit the experimental data.

Kavian, M.; Slob, E. C.; Mulder, W. A.

2012-05-01

391

What factors control the composition of andesitic sand?  

SciTech Connect

The modal composition of andesitic sand and sandstone is not only a function of source-area climate and transport processes typically considered for nonvolcanic sediment but is also strongly controlled by volcanic fragmentation and pyroclastic-transport processes. Most volcaniclastic sediment deposited penecontemporaneously with active volcanism is not epiclastic, and therefore its composition is not dependent on climate. Crystal-rich andesite sand cannot simply be regarded as the product of weathering in a humid climate. In fact, there is no relationship between precipitation and the ratio of crystals to rock fragments. Fluvial-transport abrasion demonstrably generates crystal-rich sand only in the case of porphyritic glassy rock fragments that are not durable during transport; holocrystalline pyroclastic fragments apparently do not disintegrate during transport to yield crystal-rich sand. Many sand-size primary volcanic deposits are crystal-rich as a result of eruptive processes that physical fractionate particles of different sizes and densities. Reworking of these deposits results in crystal-rich sand that is not a product of weathering or transport abrasion. The abundance of unaltered green hornblende is one measure of the importance of pyroclastic material in a volcanic sand because this mineral is not found in lava flows. Interpretation of volcaniclastic sandstone requires consideration of volcanic processes not typically considered by sedimentologists.

Smith, G.A.; Lotosky, J.E. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences

1995-01-02

392

Concentration profiles for fine and coarse sediments suspended by waves over ripples: An analytical study with the 1-DV gradient diffusion model  

E-print Network

Field and laboratory measurements of suspended sediments over wave ripples show, for time-averaged concentration profiles in semi-log plots, a contrast between upward convex profiles for fine sand and upward concave profiles for coarse sand. Careful examination of experimental data for coarse sand shows a near-bed upward convex profile beneath the main upward concave profile. Available models fail to predict these two profiles for coarse sediments. The 1-DV gradient diffusion model predicts the main upward concave profile for coarse sediments thanks to a suitable $\\beta$(y)-function (where $\\beta$ is the inverse of the turbulent Schmidt number and y is the distance from the bed). In order to predict the near-bed upward convex profile, an additional parameter {\\alpha} is needed. This parameter could be related to settling velocity ($\\alpha$ equal to inverse of dimensionless settling velocity) or to convective sediment entrainment process. The profiles are interpreted by a relation between second derivative of ...

Absi, Rafik

2010-01-01

393

1 Fine Arts and Art History FINE ARTS AND ART HISTORY  

E-print Network

1 Fine Arts and Art History FINE ARTS AND ART HISTORY Through the making of art and the study grounded in related historical and theoretical issues. In the art history curriculum, students gain an in in art history (http:// bulletin.gwu.edu/arts-sciences/fine-arts-art-history/ba-art- history) · Bachelor

Vertes, Akos

394

Testing of lateral water flow in a moisture barrier  

Microsoft Academic Search

We have performed large-scale lateral-flow tests in a fine-textured material overlying a coarser medium. The goal was to investigate the effectiveness of a moisture barrier where the finer material has the texture of a silty sand. When we tested for induced lateral flow, a geotextile inhibited penetration of two overlying materials of different particle sizes. Our wick system provided data

W. V. Abeele; G. L. DePoorter

1984-01-01

395

A herringbone bedform pattern of possible Taylor-Go??rtler type flow origin seen in sonographs  

USGS Publications Warehouse

Side-scan sonar records collected in a shallow arctic lagoon (2-2.5 m depth) reveal a herringbone pattern of current-aligned linear reflectors with branching diagonals. The major longitudinal reflectors have no detectable relief (<20 cm), are spaced 5-10 m apart, and may represent current-aligned helical cell boundaries preserved in the silty fine sand of the lagoon floor. The pattern suggests a three-dimensional flow regime of the Taylor-Go??rtler type. ?? 1979.

Toimil, L.J.; Reimnitz, E.

1979-01-01

396

Contribution of aeolian sand to backbarrier marsh sedimentation  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

397

Depositional settings of sand beaches along whitewater rivers  

USGS Publications Warehouse

The numbers and sizes of sand beaches suitable for recreation along selected whitewater rivers in the western United States depend on sand concentrations, range of discharge and the size, frequency and type of depositional settings. River-width expansions downstream from constrictions are the predominant depositional setting for sand beaches in the upper Grand Canyon and along five Wild and Scenic Rivers in Idaho, but not along other rivers. Beaches located upstream from constrictions are rare, in general, except in the Grand Canyon. Beaches found in expansions without constrictions dominate depositional sites along the Yampa and Green Rivers, are fairly common along the rivers in Idaho, but are relatively rare in the Grand Canyon. The magnitude of flow expansion is a reliable predictor of beach size. Beaches located on the inside of curves are uncommon, in general, but can be important recreation sites. The mid-channel bar setting is the least important from a recreation standpoint because that setting is rare and beaches there are typically small, and emergent only at low flow. The frequency of beaches is highly variable among rivers and the concentration of sand in transport is only partially responsible. Of the rivers studied, the unregulated Yampa River carries the highest concentrations of suspended sand and has among the most beaches (1.2 beaches km-1). Emergent sand beaches are essentially nonexistent along the Deschutes River and are rare along other Oregon rivers, yet these rivers transport some sand. Sand beaches are fairly common (0.8-1.1 beaches km-1) along the regulated Colorado River, but are comparatively rare (0.6 beaches km-1) along the unregulated Middle Fork Salmon River. The suspended sand concentrations in study reaches of these two rivers are similar, and the difference in the frequency of beaches may be largely because the processes that create beach-deposition settings are less active along the Middle Fork Salmon.

Vincent, K.R.; Andrews, E.D.

2008-01-01

398

Sediment Analysis Network for Decision Support (SANDS)  

NASA Astrophysics Data System (ADS)

Since the year 2000, Eastern Louisiana, coastal Mississippi, Alabama, and the western Florida panhandle have been affected by 28 tropical storms, seven of which were hurricanes. These tropical cyclones have significantly altered normal coastal processes and characteristics in the Gulf region through sediment disturbance. Although tides, seasonality, and agricultural development influence suspended sediment and sediment deposition over periods of time, tropical storm activity has the capability of moving the largest sediment loads in the shortest periods of time for coastal areas. The importance of sediments upon water quality, coastal erosion, habitats and nutrients has made their study and monitoring vital to decision makers in the region. Currently agencies such as United States Army Corps of Engineers (USACE), NASA, and Geological Survey of Alabama (GSA) are employing a variety of in-situ and airborne based measurements to assess and monitor sediment loading and deposition. These methods provide highly accurate information but are limited in geographic range, are not continuous over a region and, in the case of airborne LIDAR are expensive and do not recur on a regular basis. Multi-temporal and multi-spectral satellite imagery that shows tropical-storm-induced suspended sediment and storm-surge sediment deposits can provide decision makers with immediate and long-term information about the impacts of tropical storms and hurricanes. It can also be valuable for those conducting research and for projects related to coastal issues such as recovery, planning, management, and mitigation. The recently awarded Sediment Analysis Network for Decision Support will generate decision support products using NASA satellite observations from MODIS, Landsat and SeaWiFS instruments to support resource management, planning, and decision making activities in the Gulf of Mexico. Specifically, SANDS will generate decision support products that address the impacts of tropical storms and hurricanes on sediment disturbance, suspension, transport, and deposition in the north central Gulf of Mexico. At least five end user organizations plus the UAHuntsville’s Information Technology and Systems Center and the Geological Survey of Alabama project team, will use the products to improve measurements of water quality (Dauphin Island Sea Lab); assess sedimentation during storm events and its impact on critical coastal habitats (Alabama Department of Conservation); assess sedimentation versus sea level rise in natural marshes (Department of the Interior); and improve understanding of the impact of sediment and sediment deposits on water quality, living resources, and habitats of the estuarine environment (Mobile Bay National Estuary Program); and assess storm surge effects on coastal ecosystems (NOAA Center for Coastal Ocean Research). The products will be managed and accessed through the SANDS Portal, an on-line data repository with a user interface customized to provide data and information for specific storm events. By making multi-spectral satellite products available for multiple common storm events, SANDS will provide end users the opportunity to better analyze, detect, and identify compositions and patterns of suspended sediment and sediment deposits.

Hardin, D. M.; Keiser, K.; Graves, S. J.; Conover, H.; Ebersole, S.

2009-12-01

399

FINE P M EMISSIONS CHARACTERIZATION--BIOMASS  

EPA Science Inventory

FINE PM EMISSIONS CHARACTERIZATION -- BIOMASS The APPCD fine particle research team was funded (FY 2000) to perform emission characterization and source chemical profile analysis of major particle source emissions in the U.S. The focus of this task is to analyze these data on ai...

400

Amplified piezoelectric actuator with fine linear resolution  

Microsoft Academic Search

Actuators with large strokes and fine resolution have many applications, such as precise positioning, high resolution lithographing, sub-micro machining and fine manipulation of cells in biomedical fields. In this paper, a compact design of an elliptic-shaped actuator using 16 flexural hinges is presented. The device used two piezo stacks in long axis to generate amplified displacement in short axis. Overall

W. Zu; Xi-Jia Gu

2004-01-01

401

ADVANCING FINE ROOT RESEARCH WITH MINIRHIZOTRONS  

EPA Science Inventory

Minirhizotrons provide a nondestructive, in situ method for directly viewing and studying fine roots. Although many insights into fine roots have been gained using minirhizotrons, it is clear from the literature that there is still wide variation in how minirhizotrons and minirhi...

402

Air Impact on Green Sand Participants: C. Please (Mentor), S. Bohun, A. Bona, D. Chertok, J. Modayil, J. Samuel, C.  

E-print Network

of the sand mixture is compressible. It is the air fraction that makes the sand a compressible material. 2 a sand mould consists of placing sand over a pattern and then compressing the sand which has sufficient, the rapid compaction tends to create regions relatively void of sand and hence causes problems when

Bohun, C. Sean

403

George Sand et les arts du XVIIIe Introduction  

E-print Network

George Sand et les arts du XVIIIe siècle Introduction Olivier Bara (Université Lyon 2, UMR LIRE) Le présent numéro des Amis de George Sand est issu d'un séminaire organisé par l'université Lyon 2 et l'UMR LIRE, de 2008 à 2012, intitulé « George Sand et les arts du XVIIIe siècle ». Les articles ici réunis

Paris-Sud XI, Université de

404

Aerolian erosion, transport, and deposition of volcaniclastic sands among the shifting sand dunes, Christmas Lake Valley, Oregon: TIMS image analysis  

NASA Technical Reports Server (NTRS)

Remote sensing is a tool that, in the context of aeolian studies, offers a synoptic view of a dune field, sand sea, or entire desert region. Blount et al. (1990) presented one of the first studies demonstrating the power of multispectral images for interpreting the dynamic history of an aeolian sand sea. Blount's work on the Gran Desierto of Mexico used a Landsat TM scene and a linear spectral mixing model to show where different sand populations occur and along what paths these sands may have traveled before becoming incorporated into dunes. Interpretation of sand transport paths and sources in the Gran Desierto led to an improved understanding of the origin and Holocene history of the dunes. With the anticipated advent of the EOS-A platform and ASTER thermal infrared capability in 1998, it will become possible to look at continental sand seas and map sand transport paths using 8-12 mu m bands that are well-suited to tracking silicate sediments. A logical extension of Blount's work is to attempt a similar study using thermal infrared images. One such study has already begun by looking at feldspar, quartz, magnetite, and clay distributions in the Kelso Dunes of southern California. This paper describes the geology and application of TIMS image analysis of a less-well known Holocene dune field in south central Oregon using TIMS data obtained in 1991.

Edgett, Kenneth S.; Ramsey, Michael S.; Christensen, Philip R.

1995-01-01

405

Eolian dune, interdune, sand sheet, and siliciclastic Sabkha sediments of an offshore prograding Sand Sea, Dhahran area, Saudi Arabia  

SciTech Connect

An offshore prograding sand sea exists along portions of the Arabian Gulf coastline near Dhahran, Saudi Arabia. In this region, sediments of eolian dune, interdune, sand sheet, and siliciclastic sabkha intercalate with marine deposits. This depositional setting is characterized by strong offshore winds which supply abundant sand to the coastline, and cause at present time the outbuilding of the dune system. This quartz-detrital dominant setting contrasts markedly with the carbonate dominant setting resulting from onshore winds in the Trucial Coast area to the south. The broad intercalation of eolian and marine deposits which results creates ideal potential for subregional stratigraphic petroleum traps, due to pinch-out of porous and permeable dune sands into impermeable marine mudstones. Within the eolian system itself are potential reservoir rocks (dunes), sources (organic-rich sabkha and interdune deposits), and seals (zones of early cementation in all deposits). Early cementation is very common in all facies of the eolian sand sea. The early cementation occurs owing to (1) soil formation, (2) deposition of pore-filling gypsiferous cements from saturated solutions near water table, and (3) addition of sand-size windblown evaporitic material to sands downwind of sabkhas.

Fryberger, S.G.; Al-Sari, A.M.; Clisham, T.J.

1983-02-01

406

Eolian Dune, interdune, sand sheet, and Siliciclastic Sabkha sediments of an offshore prograding Sand Sea, Dhahran Area, Saudi Arabia  

SciTech Connect

An offshore prograding sand sea exists along portions of the Arabian Gulf coastline near Dhahran, Saudi Arabia. In this region, sediments of eolian dune, interdune, sand sheet, and siliciclastic sabkha intercalate with marine deposits. This depositional setting is characterized by strong offshore winds which supply abundant sand to the coastline, and cause at present time the outbuilding of the dune system. This quartz-detrital dominant setting contrasts markedly with the carbonate dominant setting resulting from onshore winds in the Trucial Coast area to the south. The broad intercalation of eolian and marine deposits which results creates ideal potential for subregional stratigraphic petroleum traps, due to pinch-out of porous and permeable dune sands into impermeable marine mudstones. Within the eolian system itself are potential reservoir rocks, sources, (organic-rich sabkha and interdune deposits), and seals (zones of early cementation in all deposits). Early cementation is very common in all facies of the eolian sand sea. The early cementation occurs owing to (1) soil formation, (2) deposition of pore-filling gypsiferous cements from saturated solutions near water table, and (3) addition of sand-size windblown evaporitic material to sands downwind of sabkhas.

Fryberger, S.G.; Al-Sari, A.M.; Clisham, T.J.

1983-02-01

407

Next-generation sequencing of microbial communities in the Athabasca River and its tributaries in relation to oil sands mining activities.  

PubMed

The Athabasca oil sands deposit is the largest reservoir of crude bitumen in the world. Recently, the soaring demand for oil and the availability of modern bitumen extraction technology have heightened exploitation of this reservoir and the potential unintended consequences of pollution in the Athabasca River. The main objective of the present study was to evaluate the potential impacts of oil sands mining on neighboring aquatic microbial community structure. Microbial communities were sampled from sediments in the Athabasca River and its tributaries as well as in oil sands tailings ponds. Bacterial and archaeal 16S rRNA genes were amplified and sequenced using next-generation sequencing technology (454 and Ion Torrent). Sediments were also analyzed for a variety of chemical and physical characteristics. Microbial communities in the fine tailings of the tailings ponds were strikingly distinct from those in the Athabasca River and tributary sediments. Microbial communities in sediments taken close to tailings ponds were more similar to those in the fine tailings of the tailings ponds than to the ones from sediments further away. Additionally, bacterial diversity was significantly lower in tailings pond sediments. Several taxonomic groups of Bacteria and Archaea showed significant correlations with the concentrations of different contaminants, highlighting their potential as bioindicators. We also extensively validated Ion Torrent sequencing in the context of environmental studies by comparing Ion Torrent and 454 data sets and by analyzing control samples. PMID:22923391

Yergeau, Etienne; Lawrence, John R; Sanschagrin, Sylvie; Waiser, Marley J; Korber, Darren R; Greer, Charles W

2012-11-01

408

Denitrification in a Sand and Gravel Aquifer  

PubMed Central

Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N2O produced (g of wet sediment)?1 h?1. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate removal from groundwater. PMID:16347621

Smith, Richard L.; Duff, John H.

1988-01-01

409

Coating of silica sand with aluminosilicate clay.  

PubMed

The objective of this work was to coat aluminosilicate clays on an inert silica support, and to characterize the properties and stability of the clay-silica coating. Two polymers, polyacrylamide (PAM) and polyvinyl alcohol (PVA), were used to bind kaolinite, illite, and smectite onto silica grains. The clay-polymer composites were studied by X-ray diffraction, FTIR, and electrophoretic mobility. Clay coatings on silica grains were characterized by mass coverage, scanning electron microscopy, specific surface area, and pH stability. Silica sand was successfully coated with clays by using the two polymers, but with PVA, the clay coating had a greater mass coverage and was more stable against pH variations. Less polymer was needed for the clay coating using PVA as compared to using PAM. Clay-polymer complexes and pure clay minerals had similar cation exchange capacities and electrophoretic mobilities, indicating that overall surface charge of the clays was little affected by the polymers. Some decrease in hydrophilicity was observed for illite and smectite when clays where coated with the polymers. The methodology reported here allows the generation of a clay-based porous matrix, with hydraulic properties that can be varied by adjusting the grain size of the inert silica support. PMID:16085082

Jerez, Jorge; Flury, Markus; Shang, Jianying; Deng, Youjun

2006-02-01

410

The role of aluminum in slow sand filtration.  

PubMed

Engineering enhancement of slow sand filtration has been an enigma in large part because the mechanisms responsible for particle removal have not been well characterized. The presumed role of biological processes in the filter ripening process nearly precluded the possibility of enhancing filter performance since interventions to enhance biological activity would have required decreasing the quality of the influent water. In previous work, we documented that an acid soluble polymer controls filter performance. The new understanding that particle removal is controlled in large part by physical chemical mechanisms has expanded the possibilities of engineering slow sand filter performance. Herein, we explore the role of naturally occurring aluminum as a ripening agent for slow sand filters and the possibility of using a low dose of alum to improve filter performance or to ripen slow sand filters. PMID:17276479

Weber-Shirk, Monroe L; Chan, Kwok Loon

2007-03-01

411

Documenting the global impacts of beach sand mining  

NASA Astrophysics Data System (ADS)

For centuries, beach sand has been mined for use as aggregate in concrete, for heavy minerals, and for construction fill. The global extent and impact of this phenomenon has gone relatively unnoticed by academics, NGOs, and major news sources. Most reports of sand mining activities are found at the very local scale (if the mining is ever documented at all). Yet, sand mining in many localities has resulted in the complete destruction of beach (and related) ecosystems along with severe impacts to coastal protection and tourism. The Program for the Study of Developed Shorelines at Western Carolina University and Beachcare.org have initiated the construction of a global database of beach sand mining activities. The database is being built through a combination of site visits and through the data mining of media resources, peer reviewed papers, and reports from private and governmental entities. Currently, we have documented sand mining in 35 countries on 6 continents representing the removal of millions of cubic meters of sand. Problems extend from Asia where critical infrastructure has been disrupted by sand mining to the Caribbean where policy reform has swiftly followed a highly publicized theft of sand. The Program for the Study of Developed Shorelines recently observed extensive sand mining in Morocco at the regional scale. Tens of kilometers of beach have been stripped of sand and the mining continues southward reducing hope of a thriving tourism-based economy. Problems caused by beach sand mining include: destruction of natural beaches and the ecosystems they protect (e.g. dunes, wetlands), habitat loss for globally important species (e.g. turtles, shorebirds), destruction of nearshore marine ecosystems, increased shoreline erosion rates, reduced protection from storms, tsunamis, and wave events, and economic losses through tourist abandonment and loss of coastal aesthetics. The threats posed by sand mining are made even more critical given the prospect of a significant rise in global sea level over the coming decades. Most governments recognize the local impacts of sand mining and mining activities are illegal in many localities. However, enforcement of these protections has been problematic and there has been little pressure to stop the practice from local or international environmental groups. In many cases, addressing the issue of sand mining requires addressing the local issues that allow it to persist. This includes poverty, corruption, and unregulated development. In areas where beach sand mining significantly supports the local economy, care needs to be given that local workers are given alternative means of income, and builders are provided an affordable substitute for the sand (e.g. crushed rock). Regardless, it is time for both academics and NGOs to address the cumulative environmental impacts of the direct destruction of the world's beaches through mining activities.

Young, R.; Griffith, A.

2009-04-01

412

Electric fields in unsteady wind-blown sand.  

PubMed

The electrification of wind-blown sand has been widely confirmed by field and wind-tunnel measurements. It plays an important role in the lifting and transport of sand particles. In this study we investigated the behavior of electric fields in unsteady saltation by adopting periodic variation wind sequences. The influence of electric fields on sand transport rate was also discussed. The results show that both horizontal and vertical electric fields exist in unsteady saltation, and the transport rate in unsteady saltation is less than that in steady saltation. An interesting result is that the directions of vertical electric field fluctuate upward and downward-pointing with time in the unsteady saltation. This provides a possible explanation for the bipolar pattern of the vertical electric field in wind-blown sand. PMID:24574056

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

2014-02-01

413

2. VIEW SHOWING NATURAL SAND BEACH ON KIDNEY LAKE, LOOKING ...  

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

2. VIEW SHOWING NATURAL SAND BEACH ON KIDNEY LAKE, LOOKING WEST - High Mountain Dams in Upalco Unit, Kidney Lake Dam, Ashley National Forest, 4.7 miles North of Miners Gulch Campground, Mountain Home, Duchesne County, UT

414

1. Salmon Creek Diversion Dam, weir (to left), sand and ...  

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

1. Salmon Creek Diversion Dam, weir (to left), sand and silt sluice gate (center), main canal headworks (to right), view to northwest - Salmon Creek Diversion Dam, Salmon Creek, Okanogan, Okanogan County, WA

415

MAIN CANAL HEADWORKS, FROM DOWNSTREAM (TO RIGHT), NOTE SAND AND ...  

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

MAIN CANAL HEADWORKS, FROM DOWNSTREAM (TO RIGHT), NOTE SAND AND SILT SLUICE GATE FOR DIVERSION DAM ON LEFT, VIEW TO NORTHWEST - Salmon Creek Diversion Dam, Main Canal Headworks, Salmon Creek, Okanogan, Okanogan County, WA

416

Automated texture recognition of quartz sand grains for forensic applications.  

PubMed

Quartz sand surface texture analysis has been automated for the first time for forensic application. The derived Basic Image Features (BIFs) provide computer-generated texture recognition from preexisting data sets. The technique was applied to two distinct classification problems; first, the ability of the system to discriminate between (quartz) sand grains with upturned plate features (indicative of eolian, global sand sea environments) and grains that do not exhibit these features. A success rate of grain classification of 98.8% was achieved. Second, to test the ability of the computer recognition system to identify specific energy levels of formation of the upturned plate surface texture features. Such recognition ability has to date been beyond manual geological interpretation. The discrimination performance was enhanced to an exact classification success rate of 81%. The enhanced potential for routine forensic investigation of the provenance of common quartz sand is indicated. PMID:22458862

Newell, Andrew J; Morgan, Ruth M; Griffin, Lewis D; Bull, Peter A; Marshall, John R; Graham, Giles

2012-09-01

417

View of concrete sand bag form concentration in the Merry ...  

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

View of concrete sand bag form concentration in the Merry Generator House Southeast corner, looking north - Arthur Holmes Merry Generator House, Signal Lake North of Range Road, Fort Gordon, Richmond County, GA

418

View of South half of concrete sand bag form concentration ...  

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

View of South half of concrete sand bag form concentration in the Merry Generator House Southeast corner, ooking east - Arthur Holmes Merry Generator House, Signal Lake North of Range Road, Fort Gordon, Richmond County, GA

419

View of North half of concrete sand bag form concentration ...  

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

View of North half of concrete sand bag form concentration in the Merry Generator House southeast corner, looking east - Arthur Holmes Merry Generator House, Signal Lake North of Range Road, Fort Gordon, Richmond County, GA

420

MOLD MACHINE, BRASS FOUNDRY, USED TO COMPRESS CONDITIONED SAND IN ...  

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

MOLD MACHINE, BRASS FOUNDRY, USED TO COMPRESS CONDITIONED SAND IN FLASKS OVER PATTERNS TO CREATE MOLD CAVITIES WHICH ARE LATER FILLED WITH MOLTEN BRONZE. - Stockham Pipe & Fittings Company, Brass Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

421

31. VIEW OF DEMOLITION OF FOUNDRY SAND BLASTING AND CLEANING ...  

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

31. VIEW OF DEMOLITION OF FOUNDRY SAND BLASTING AND CLEANING BUILDING FROM INSIDE FOUNDRY. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

422

33. VIEW OF ROOF TRUSSING SYSTEM OF SAND BLASTING AND ...  

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

33. VIEW OF ROOF TRUSSING SYSTEM OF SAND BLASTING AND CLEANING BUILDING. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

423

32. VIEW OF DEMOLISHED FOUNDRY SAND BLASTING AND CLEANING BUILDING ...  

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

32. VIEW OF DEMOLISHED FOUNDRY SAND BLASTING AND CLEANING BUILDING AFTER DUST HAS SETTLED. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

424

29. DETAIL VIEW OF FOUNDRY SAND BLASTING AND CLEANING BUILDING ...  

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

29. DETAIL VIEW OF FOUNDRY SAND BLASTING AND CLEANING BUILDING UNDER DEMOLITION. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

425

30. VIEW OF DEMOLITION OF FOUNDRY SAND BLASTING AND CLEANING ...  

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

30. VIEW OF DEMOLITION OF FOUNDRY SAND BLASTING AND CLEANING BUILDING FROM INSIDE FOUNDRY. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

426

28. VIEW OF FOUNDRY SAND BLASTING AND CLEANING BUILDING UNDER ...  

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

28. VIEW OF FOUNDRY SAND BLASTING AND CLEANING BUILDING UNDER DEMOLITION. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

427

34. INTERIOR VIEW INSIDE PARTIALLY DEMOLISHED SAND BLASTING AND CLEANING ...  

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

34. INTERIOR VIEW INSIDE PARTIALLY DEMOLISHED SAND BLASTING AND CLEANING BUILDING LOOKING AT THE ELEVATION OF FOUNDRY. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

428

DEGRADATION AND MIGRATION OF VINCLOZOLIN IN SAND AND SOIL  

EPA Science Inventory

The migration of the dicarboximide fungicide vinclozolin and its principal degradation products through porous media was experimentally determined by simulating pesticide applications to a 23-30 mesh Ottawa sand and a North Carolina Piedmont, aquic hapludult soil in laboratory ...

429

Aerial view of old station and sand dunes looking east ...  

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

Aerial view of old station and sand dunes looking east from tower of newer station. - Vermilion Life Saving Station, Shore of Lake Superior, 10 miles west of Whitefish Point, Paradise, Chippewa County, MI

430

7 CFR 319.56-57 - Sand pears from China.  

...Guignardia pyricola (Nose) W. Yamamoto, a phytopathogenic fungus; Monilinia fructigena Honey in Whetzel, the cause of brown...mealybug; and Venturia nashicola Tanaka and Yamamoto, pear scab fungus. The conditions for importation of all fresh sand...

2014-01-01

431

7 CFR 319.56-57 - Sand pears from China.  

Code of Federal Regulations, 2013 CFR

...Guignardia pyricola (Nose) W. Yamamoto, a phytopathogenic fungus; Monilinia fructigena Honey in Whetzel, the cause of brown...mealybug; and Venturia nashicola Tanaka and Yamamoto, pear scab fungus. The conditions for importation of all fresh sand...

2013-01-01

432

Aviation: From Sand Dunes to Sonic Booms  

NSDL National Science Digital Library

Starting with its rather lyrical title, visitors to this particular National Register of Historic Places Travel Itinerary website will be taken on a breezy and visually stimulating tour of some of the sites that document Americaâ??s aviation history. All told, the site provides information about over 100 sites, including airfields, research and testing facilities, and launch and control facilities. From the homepage, visitors can peruse a list of the sites, look for sites using an interactive map, and read essays on air power, modern aviation, and, not surprisingly, the Wright Brothers. While the sites are spread across 35 states and several US territories, creative voyagers could easily create a number of interesting journeys. Additionally, the site offers a fine set of external links under the â??Learn Moreâ? tab.

433

Reconnaissance examination of selected oil-sand outcrops in Wyoming  

Microsoft Academic Search

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

Ver Ploeg

1986-01-01

434

Evaluating Shoreline Response to Offshore Sand Mining for Beach Nourishment  

Microsoft Academic Search

KELLEY, S.W.; RAMSEY, J.S., and BYRNES, M.R., 2004. Evaluating shoreline response to offshore sand mining for beach nourishment. Journal of Coastal Research, 20(1), 89-100. West Palm Beach (Florida), ISSN 0749-0208. An analytical approach that incorporates analysis of nearshore wave transformation and wave-induced longshore sediment transport was developed to quantify the significance of potential physical environmental impacts associated with offshore sand

Sean W. Kelley; John S. Ramsey; Mark R. Byrnes

2004-01-01

435

Thermoelastic Enhancement of Damping of Sand Using Synthetic Ground Rubber  

Microsoft Academic Search

This paper examines the possibility of introducing synthetic rubber in constructed earthen systems to improve their vibration attenuation. The results of a series of controlled laboratory tests—aimed to investigate the improvement of low-strain dynamic properties of Ottawa sand by mixing ground rubber of similar size—showed a simultaneous increase in both the shear modulus and the damping ratio of the sand

Sibel Pamukcu; Suat Akbulut

2006-01-01

436

Drainage in heterogeneous sand columns with different geometric structures  

Microsoft Academic Search

This paper discusses multi-step drainage experiments in two heterogeneously packed sand columns (10×10×20cm3). Different packing structures were generated using two different sand types. One purpose of the study was to test the influence of packing structures on the movement of water. The second purpose was to assess the quality of predictions for the outflow curves in both columns made with

M. Vasin; P. Lehmann; A. Kaestner; R. Hassanein; W. Nowak; R. Helmig; I. Neuweiler

2008-01-01

437

Antimicrobial sand via adsorption of cationic Moringa oleifera protein.  

PubMed

Moringa oleifera (Moringa) seeds contain a natural cationic protein (MOCP) that can be used as an antimicrobial flocculant for water clarification. Currently, the main barrier to using Moringa seeds for producing potable water is that the seeds release other water-soluble proteins and organic matter, which increase the concentration of dissolved organic matter (DOM) in the water. The presence of this DOM supports the regrowth of pathogens in treated water, preventing its storage and later use. A new strategy has been established for retaining the MOCP protein and its ability to clarify and disinfect water while removing the excess organic matter. The MOCP is first adsorbed and immobilized onto sand granules, followed by a rinsing step wherein the excess organic matter is removed, thereby preventing later growth of bacteria in the purified water. Our hypotheses are that the protein remains adsorbed onto the sand after the functionalization treatment, and that the ability of the antimicrobial functionalized sand (f-sand) to clarify turbidity and kill bacteria, as MOCP does in bulk solution, is maintained. The data support these hypotheses, indicating that the f-sand removes silica microspheres and pathogens from water, renders adhered Escherichia coli bacteria nonviable, and reduces turbidity of a kaolin suspension. The antimicrobial properties of f-sand were assessed using fluorescent (live-dead) staining of bacteria on the surface of the f-sand. The DOM that can contribute to bacterial regrowth was shown to be significantly reduced in solution, by measuring biochemical oxygen demand (BOD). Overall, these results open the possibility that immobilization of the MOCP protein onto sand can provide a simple, locally sustainable process for producing storable drinking water. PMID:22129164

Jerri, Huda A; Adolfsen, Kristin J; McCullough, Lauren R; Velegol, Darrell; Velegol, Stephanie B

2012-01-31

438

Creating and maintaining a gas cap in tar sands formations  

DOEpatents

Methods for treating a tar sands formation are disclosed herein. Methods for treating a tar sands formation may include providing heat to at least part of a hydrocarbon layer in the formation from one or more heaters located in the formation. Pressure may be allowed to increase in an upper portion of the formation to provide a gas cap in the upper portion. At least some hydrocarbons are produced from a lower portion of the formation.

Vinegar, Harold J. (Bellaire, TX); Karanikas, John Michael (Houston, TX); Dinkoruk, Deniz Sumnu (Houston, TX); Wellington, Scott Lee (Bellaire, TX)

2010-03-16

439

Which processes form the volcanic sands on Mars?  

NASA Astrophysics Data System (ADS)

Volcanic sands are common at the surface of Mars. They are usually of basaltic composition. Occurrence of sands, mostly recognized as dark dune fields include numerous impact craters in the southern hemisphere [1], several volcanic provinces such as Cerberus and Syrtis Major[2], several impact craters in the northern hemisphere, the large basins (Hellas and Argyre), Valles Marineris, and the poles [3]. In most cases, the sands are of basaltic composition [2,4], at the exception of the polar dunes which are made of sulfates [3]. It is interesting to note that dunes have been found on the Hesperian volcanic plateau of Systis Major, while they are not reported on Tyrrhena Terra, a volcanic province similar in age and morphology to Syrtis. It seems thus that the formation of sand from volcanic material is not systematic and thus requires particular conditions. These different situations which will be presented raise the following questions. When did these volcanic sands form in the Martian history? Did they result from a long-standing and slow process operating in the present cold conditions or did they result from several episodes associated for instant to climate changes? We review several mechanisms which could account for the formation of volcanic sand on Mars from the volcanic material. In particular, we focus on the role of cold-climate processes from an analysis of terrestrial analogs in Iceland. In this case, the advance and retreat of glaciers over a recent erupted shield volcano associated with the strong catabatic winds have resulted in the rapid formation (less than few thousands years) of large volumes of sands. [1] Fenton, L. K. (2005), Potential sand source